| 1. |
- Ali, Abukar, 1988, et al.
(författare)
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CTLA4-Ig but not anti-TNF therapy promotes staphylococcal septic arthritis in mice.
- 2015
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Ingår i: The Journal of infectious diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 212:8, s. 1308-1316
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Tidskriftsartikel (refereegranskat)abstract
- The development of biologics has greatly increased the quality of life as well as the life expectancy of many RA patients. However, a large number of these patients are at an increased risk of developing serious infections. The aim of this study was to examine differential effects of anti-TNF versus CTLA4-Ig treatment on both immunological response and host defense in a murine model of septic arthritis.
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| 2. |
- Ali, Abukar, 1988, et al.
(författare)
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IL-1 Receptor Antagonist Treatment Aggravates Staphylococcal Septic Arthritis and Sepsis in Mice.
- 2015
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 10:7
-
Tidskriftsartikel (refereegranskat)abstract
- Interleukin-1 receptor antagonist (IL-1Ra) is the primary therapy against autoinflammatory syndromes with robust efficacy in reducing systemic inflammation and associated organ injury. However, patients receiving IL-1Ra might be at increased risk of acquiring serious infections.
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| 3. |
- Amirbeagi, Firoozeh, et al.
(författare)
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Determination of Subset-Restricted Anti-neutrophil Cytoplasmic Antibodies (ANCA) by Immunofluorescence Cytochemistry.
- 2019
-
Ingår i: Methods in molecular biology (Clifton, N.J.). - New York, NY : Springer New York. - 1940-6029. ; , s. 63-77
-
Bokkapitel (refereegranskat)abstract
- Neutrophils have long been considered a homogeneous cell type where all circulating cells of a particular individual express the same proteins. Lately, however, this view is changing and distinct neutrophil subsets, defined by the presence or absence of different proteins, are being increasingly recognized. At least two separate protein markers, CD177 and Olfactomedin-4 (OLFM4) are known to be expressed by some, but not all, circulating neutrophils of a given individual. We recently described the existence of subset-restricted serum autoantibodies targeting OLFM4; these were discovered during clinical testing for anti-neutrophil cytoplasmic antibodies (ANCAs). ANCA testing is part of the clinical examinations routinely carried out to support diagnosis of suspected autoimmune conditions, especially vasculitis. Positive sera typically react with all neutrophils from a single donor, whereas subset-restricted ANCA sera (such as those containing anti-OLFM4 antibodies) only react with a fraction of neutrophils. Described in this chapter is an indirect immunofluorescence (IIF) approach to test human sera for the presence of subset-restricted ANCA as well as instructions for costaining experiments using sera and purified antibodies directed against established subset markers.
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| 4. |
- Amirbeagi, Firoozeh, et al.
(författare)
-
Olfactomedin-4 autoantibodies give unusual c-ANCA staining patterns with reactivity to a subpopulation of neutrophils.
- 2015
-
Ingår i: Journal of leukocyte biology. - 1938-3673. ; 97:1, s. 181-189
-
Tidskriftsartikel (refereegranskat)abstract
- Testing for the presence of ANCAs in circulation is part of the clinical examinations routinely performed upon suspected autoimmune disorders, mainly vasculitis. The autoantibodies are typically directed toward neutrophil MPO or PR3. These are major granule-localized proteins, and similar to all hitherto-described ANCA antigens, they are expressed by all neutrophils, and ANCA-containing sera thus give rise to uniform reactivity toward all neutrophils in a sample. In this paper, we describe sera from 2 unrelated patients with diffuse inflammatory symptoms that gave rise to peculiar c-ANCA patterns, only reacting with a subpopulation (roughly 30%) of human neutrophils. By immunoblotting, both sera reacted to the same antigen, which was expressed in intracellular granules. The antigen could be released to the extracellular milieu through secretion but also through the formation of NETs. Neutrophils have long been considered a homogenous cell population, but it is becoming increasingly clear that distinct subpopulations, defined by the presence or absence of certain proteins, exist. One such marker that defines a neutrophil subset is the granule protein OLFM4. The unusual, subset-restricted c-ANCA sera reacted only with OLFM4-positive neutrophils, and MS analysis revealed that the autoantigen was, in fact, OLFM4. These data describe for the first time a c-ANCA pattern reactive to only a subpopulation of neutrophils and identify the granule protein OLFM4 as a novel autoantigen.
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| 5. |
- Andersson, Karin, 1972, et al.
(författare)
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Survivin co-ordinates formation of follicular T-cells acting in synergy with Bcl-6
- 2015
-
Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 6:24, s. 20043-20057
-
Tidskriftsartikel (refereegranskat)abstract
- Follicular T helper (Tfh) cells are recognized by the expression of CXCR5 and the transcriptional regulator Bcl-6. Tfh cells control B cell maturation and antibody production, and if deregulated, may lead to autoimmunity. Here, we study the role of the proto-oncogene survivin in the formation of Tfh cells. We show that blood Tfh cells of patients with the autoimmune condition rheumatoid arthritis, have intracellular expression of survivin. Survivin was co-localized with Bcl-6 in the nuclei of CXCR5(+)CD4 lymphocytes and was immunoprecipitated with the Bcl-6 responsive element of the target genes. Inhibition of survivin in arthritic mice led to the reduction of CXCR5(+) Tfh cells and to low production of autoantibodies. Exposure to survivin activated STAT3 and induced enrichment of PD-1(+)Bcl-6(+) subset within Tfh cells. Collectively, our study demonstrates that survivin belongs to the Tfh cell phenotype and ensures their optimal function by regulating transcriptional activity of Bcl-6.
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| 6. |
- Björkman, Lena, 1965, et al.
(författare)
-
Neutrophil recruitment to inflamed joints can occur without cellular priming.
- 2019
-
Ingår i: Journal of leukocyte biology. - 1938-3673. ; 105:6, s. 1123-1130
-
Tidskriftsartikel (refereegranskat)abstract
- Recruitment of neutrophils from blood to tissues is a cardinal event in inflammation during which neutrophils switch from a resting, naive state to a preactivated, primed phenotype; the priming process is characterized by alterations in the composition of cell surface adhesins, for example, shedding of l-selectin and mobilization of granule-stored integrins to the cell surface. Ligation of chemotactic receptors and interactions with the endothelial lining are established triggers of neutrophil priming and in line with this, in vivo transmigrated neutrophils obtained from tissues are typically highly primed. We here characterize the priming of neutrophils brought about by in vivo recruitment from blood to inflamed joints by the analyses of synovial fluid and blood from patients with inflammatory arthritis. For comparisons, we used controlled in vivo models of neutrophil transmigration to skin of healthy subjects. In contrast to the residing view and in vivo transmigrated neutrophils from skin models, neutrophils from synovial fluid were often surprisingly resting and phenotypically very similar to naive cells isolated from peripheral blood; synovial fluid cells often retained l-selectin and had undergone minimal up-regulation of integrin receptors. In complete agreement with our in vivo findings, cell-free synovial fluid was potently chemotactic without triggering alteration of surface receptors also in vitro. We conclude that tissue recruitment of neutrophils does not by default trigger l-selectin shedding and granule mobilization, and the chemoattractant(s) guiding neutrophils to synovial fluid apparently operate without inducing cellular priming.
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| 7. |
- Björnsdottir, Halla, et al.
(författare)
-
Inhibition of phospholipase A(2) abrogates intracellular processing of NADPH-oxidase derived reactive oxygen species in human neutrophils.
- 2013
-
Ingår i: Experimental cell research. - : Elsevier BV. - 1090-2422 .- 0014-4827. ; 319:5, s. 761-774
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Tidskriftsartikel (refereegranskat)abstract
- Upon activation of human neutrophils, superoxide can be produced at two cellular sites; either in the plasma membrane, giving extracellular release of oxidants, or in intracellular organelles, resulting in oxidants being retained in the cell. The involvement of phospholipase A(2) (PLA(2)) in phorbol myristate acetate (PMA)-induced activation of the two pools of NADPH-oxidase was investigated using a variety of PLA(2) inhibitors and the oxidase activity was measured by luminol/isoluminol-amplified chemiluminescence (CL). Two of the seven inhibitors were without effect, two inhibitors inhibited both intra- and extracellular ROS production equally, and three inhibitors inhibited intracellular but not extracellular CL. Using another technique to measure ROS, PHPA oxidation, we found that intracellular ROS production was unaltered with the three last inhibitors, indicating that PLA(2) is not involved in the NADPH-oxidase activity per se, but in the intracellular processing of the radicals necessary for the CL reaction to take place. The PLA(2) inhibitors did not abolish the activity of myeloperoxidase (MPO), an enzyme necessary for intracellular CL to occur. Instead, we suggest that these PLA(2) inhibitors block heterotypic granule fusion and prohibit the colocalization of ROS and MPO needed for intracellular CL activity.
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| 8. |
- Björnsdottir, Halla, et al.
(författare)
-
Neutrophil NET formation is regulated from the inside by myeloperoxidase-processed reactive oxygen species.
- 2015
-
Ingår i: Free radical biology & medicine. - : Elsevier BV. - 1873-4596 .- 0891-5849. ; 89, s. 1024-1035
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil extracellular traps (NETs) are mesh-like DNA fibers clad with intracellular proteins that are cast out from neutrophils in response to certain stimuli. The process is thought to depend on reactive oxygen species (ROS) generated by the phagocyte NADPH-oxidase and the ROS-modulating granule enzyme myeloperoxidase (MPO), but when, how, and where these factors contribute is so far uncertain. The neutrophil NADPH-oxidase can be activated at different cellular sites and ROS may be produced and processed by MPO within intracellular granules, even in situations where a phagosome is not formed, e.g., upon stimulation with phorbol myristate acetate (PMA).
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| 9. |
- Björnsdottir, Halla, et al.
(författare)
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Phenol-soluble Modulin α Peptide Toxins from aggressive Staphylococcus aureus induce rapid Formation of neutrophil extracellular Traps through a reactive Oxygen species-independent Pathway
- 2017
-
Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Neutrophils have the ability to capture and kill microbes extracellularly through the formation of neutrophil extracellular traps (NETs). These are DNA and protein structures that neutrophils release extracellularly and are believed to function as a defense mechanism against microbes. The classic NET formation process, triggered by, e.g., bacteria, fungi, or by direct stimulation of protein kinase C through phorbol myristate acetate, is an active process that takes several hours and relies on the production of reactive oxygen species (ROS) that are further modified by myeloperoxidase (MPO). We show here that NET-like structures can also be formed by neutrophils after interaction with phenol-soluble modulin alpha (PSM alpha) that are cytotoxic membrane-disturbing peptides, secreted from community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). The PSMa-induced NETs contained the typical protein markers and were able to capture microbes. The PSMa-induced NET structures were disintegrated upon prolonged exposure to DNase-positive S. aureus but not on exposure to DNase-negative Candida albicans. Opposed to classic NETosis, PSMa-triggered NET formation occurred very rapidly, independently of ROS or MPO, and was also manifest at 4 degrees C. These data indicate that rapid NETs release may result from cytotoxic membrane disturbance by PSMa peptides, a process that may be of importance for CA-MRSA virulence.
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| 10. |
- Björnsdottir, Halla, et al.
(författare)
-
Quantification of heterotypic granule fusion in human neutrophils by imaging flow cytometry.
- 2016
-
Ingår i: Data in brief. - : Elsevier BV. - 2352-3409. ; 6, s. 386-93
-
Tidskriftsartikel (refereegranskat)abstract
- Human neutrophils are filled with intracellular storage organelles, called granules and secretory vesicles, which differ in their content of soluble matrix proteins and membrane-bound molecules. To date, at least four distinct granule/vesicle subsets have been identified. These organelles may secrete their content extracellularly following mobilization to and fusion with the plasma membrane, but some of them may also fuse with internal membrane-enclosed organelles, typically a plasma membrane-derived phagosome. There are also instances where different granules appear to fuse with one another, a process that would enable mixing of their matrix and membrane components. Such granule fusion enables e.g., myeloperoxidase-processing of intragranular oxygen radicals, a key event in the formation of neutrophil extracellular traps (Björnsdottir et al., 2015)[1]. Described herein are data that show the quantification of such heterotypic granule-granule fusion by the use of imaging flow cytometry, a technique that combines flow cytometry with microscopy. The analysis described is based on immunofluorescent staining of established granule markers (lactoferrin and/or NGAL for one granule subset; the specific granules, and CD63 for another granule subset, the azurophil granules) and calculation of a colocalization score for resting and PMA-stimulated neutrophils.
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| 11. |
- Davidsson, Lisa, et al.
(författare)
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A simple skin blister technique for the study of in vivo transmigration of human leukocytes.
- 2013
-
Ingår i: Journal of immunological methods. - : Elsevier BV. - 1872-7905 .- 0022-1759. ; 393:1-2, s. 8-17
-
Tidskriftsartikel (refereegranskat)abstract
- The study of human leukocytes is almost exclusively conducted using cells isolated from peripheral blood. This is especially true for neutrophils, despite the fact that these cells are of main (pathological) importance in extravascular tissues upon e.g., infection and/or tissue damage. The journey from circulation to tissue is typically associated with a number of cellular changes, making the cells primed, or hyper-responsive, and in many aspects distinct from the cells present in circulation. Models to obtain in vivo transmigrated leukocytes from human tissue are available, but not widely used. We describe here an easy-to-use model for the study of local inflammation, stemming from limited tissue damage, which can be used to isolate viable and functional leukocytes. The model is based on the generation of aseptic skin blisters, formed by the application of negative pressure, and allows for investigations of the cellular infiltrate as well as of soluble mediators present in the exudate. We believe that this method, combined with modern analysis equipment suitable for small volumes and cell numbers, could be of great use for increasing our understanding of the nature and function of leukocytes that have left circulation and transmigrated to inflamed tissues.
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| 12. |
- Eklund, Daniel, 1984-, et al.
(författare)
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Human Gene Variants Linked to Enhanced NLRP3 Activity Limit Intramacrophage Growth of Mycobacterium tuberculosis
- 2014
-
Ingår i: Journal of Infectious Diseases. - Cary, USA : Oxford University Press. - 0022-1899 .- 1537-6613. ; 209:5, s. 749-753
-
Tidskriftsartikel (refereegranskat)abstract
- Activation of the NLRP3 inflammasome and subsequent generation of interleukin 1 beta is initiated in macrophages upon recognition of several stimuli. In the present work, we show that gain-of-function gene variants of inflammasome components known to predispose individuals to inflammatory disorders have a host-protective role during infection with Mycobacterium tuberculosis. By isolation of macrophages from patients and healthy blood donors with genetic variants in NLRP3 and CARD8 and subsequent infection of the cells with virulent M. tuberculosis, we show that these gene variants, combined, are associated with increased control of bacterial growth in human macrophages.
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| 13. |
- Elmwall, Jonas, et al.
(författare)
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Galectin-3 Is a Target for Proteases Involved in the Virulence of Staphylococcus aureus
- 2017
-
Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 85:7
-
Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is a major cause of skin and soft tissue infection. The bacterium expresses four major proteases that are emerging as virulence factors: aureolysin (Aur), V8 protease (SspA), staphopain A (ScpA), and staphopain B (SspB). We hypothesized that human galectin-3, a beta-galactoside-binding lectin involved in immune regulation and antimicrobial defense, is a target for these proteases and that proteolysis of galectin-3 is a novel immune evasion mechanism. Indeed, supernatants from laboratory strains and clinical isolates of S. aureus caused galectin-3 degradation. Similar proteolytic capacities were found in Staphylococcus epidermidis isolates but not in Staphylococcus saprophyticus. Galectin-3-induced activation of the neutrophil NADPH oxidase was abrogated by bacterium-derived proteolysis of galectin-3, and SspB was identified as the major protease responsible. The impact of galectin-3 and protease expression on S. aureus virulence was studied in a murine skin infection model. In galectin-3 (+)/(+) mice, SspB-expressing S. aureus caused larger lesions and resulted in higher bacterial loads than protease-lacking bacteria. No such difference in bacterial load or lesion size was detected in galectin-3 (+)/(+) mice, which overall showed smaller lesion sizes than the galectin-3 (+)/(+) animals. In conclusion, the staphylococcal protease SspB inactivates galectin-3, abrogating its stimulation of oxygen radical production in human neutrophils and increasing tissue damage during skin infection.
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| 14. |
- Gabl, Michael, et al.
(författare)
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P2Y2 receptor signaling in neutrophils Is regulated from inside by a novel cytoskeleton-dependent mechanism.
- 2015
-
Ingår i: Experimental cell research. - : Elsevier BV. - 1090-2422 .- 0014-4827. ; 336:2, s. 242-52
-
Tidskriftsartikel (refereegranskat)abstract
- Functional selectivity, a process by which G-protein coupled receptors (GPCRs) can activate one signaling route while avoiding another, is regulated by ligand-mediated stabilization of specific receptor states that modulate different downstream signaling events. We propose a novel mechanism for functional selectivity, induced by the endogenous P2Y2R agonist ATP and regulated at the signaling interface by the cytoskeleton. Upon ATP stimulation of human neutrophils, a transient rise in the cytosolic concentration of free Ca(2+) was not followed by activation of the superoxide anion-generating NADPH-oxidase. This was in contrast to signals generated through the formyl peptide receptor 1 (FPR1), as its activation was accompanied by both a mobilization of Ca(2+) and activation of the NADPH-oxidase. The phospholipase C/Ca(2+) signaling route is not modulated by the cytoskeleton-disrupting drug latrunculin A, but this drug was able to launch a new signaling route downstream of P2Y2R that led to NADPH-oxidase activation. The signaling downstream of P2Y2R was rapidly terminated and the receptors were desensitized; however, in contrast to desensitized FPR1, no P2Y2 receptor reactivation could be induced by latrunculin A. Thus, P2Y2R desensitization does not appear to involve the cytoskeleton, contrary to FPR1 desensitization. In summary, we hereby describe how ATP regulates functional selectivity via the cytoskeleton, leading to intracellular Ca(2+) increase, alone or with simultaneous NADPH-oxidase activation in neutrophils.
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| 15. |
- Johansson, Jessika, 1990, et al.
(författare)
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Phagocyte interactions with Mycobacterium tuberculosis - Simultaneous analysis of phagocytosis, phagosome maturation and intracellular replication by imaging flow cytometry.
- 2015
-
Ingår i: Journal of immunological methods. - : Elsevier BV. - 1872-7905 .- 0022-1759. ; 427, s. 73-84
-
Tidskriftsartikel (refereegranskat)abstract
- Utilization of compounds that enhance the innate immune response against Mycobacterium tuberculosis is an attractive strategy for combating tuberculosis in the post-antibiotic era. Thus, it is crucial to develop methods that can be used to screen for such compounds and to investigate their mechanisms of action. Here, we used imaging flow cytometry (ImageStreamX Mk II), which enables rapid quantification of microscopic images in flow, to study the interaction between phagocytes and M. tuberculosis. Macrophage-differentiated THP-1 cells were infected with GFP-expressing M. tuberculosis H37Ra, and methods for rapidly assessing phagocytosis, phagosome maturation, and bacterial replication inside the cells were developed and evaluated. These aspects of innate immunity are essential in determining the outcome of mycobacterial infection of phagocytes. The technique was found effective for monitoring phagocytosis of mycobacteria, phagosomal acidification and phagolysosomal fusion, as well as for measuring mycobacterial replication inside the cells. Several of these aspects could be analyzed simultaneously in the same sample, providing a great deal of information about the phagocyte–mycobacterial interaction at once. Thus, this method has great potential to be useful both for basic research questions and for evaluating compounds that enhance the innate immune response against M. tuberculosis.
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| 16. |
- Lingblom, Christine, 1984, et al.
(författare)
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Eosinophils from eosinophilic oesophagitis patients have T cell suppressive capacity and express FOXP3.
- 2017
-
Ingår i: Clinical and Experimental Immunology. - : Oxford University Press (OUP). - 1365-2249 .- 0009-9104. ; 187:3, s. 455-465
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Tidskriftsartikel (refereegranskat)abstract
- Eosinophilic esophagitis (EoE) is an antigen-driven T cell-mediated chronic inflammatory disease where food and environmental antigens are thought to have a role. Human eosinophils express the immunoregulatory protein galectin-10 and have T cell suppressive capacity similar to regulatory T cells (Tregs ). We hypothesized that one function of eosinophils in EoE might be to regulate the T cell-driven inflammation in the oesophagus. This was tested by evaluating the suppressive capacity of eosinophils isolated from the blood of adult EoE patients in a mixed lymphocyte reaction. In addition, eosinophilic expression of forkhead box protein 3 (FOXP3), the canonical transcription factor of Tregs , was determined by conventional and imaging flow cytometry, quantitative polymerase chain reaction (qPCR), confocal microscopy and immunoblotting. It was found that blood eosinophils from EoE patients had T cell suppressive capacity, and that a fraction of the eosinophils expressed FOXP3. A comparison of EoE eosinophils with healthy control eosinophils indicated that the patients' eosinophils had inferior suppressive capacity. Furthermore, a higher percentage of the EoE eosinophils expressed FOXP3 protein compared with the healthy eosinophils, and they also had higher FOXP3 protein and mRNA levels. FOXP3 was found in the cytosol and nucleus of the eosinophils from both the patients and healthy individuals, contrasting with the strict nuclear localization of FOXP3 in Tregs . To conclude, these findings suggest that the immunoregulatory function of eosinophils may be impaired in EoE.
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| 17. |
- Linge, Helena, et al.
(författare)
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Midkine is expressed and differentially processed during COPD exacerbations and ventilator-associated pneumonia associated with Staphylococcus aureus infection.
- 2013
-
Ingår i: Molecular medicine (Cambridge, Mass.). - : Springer Science and Business Media LLC. - 1528-3658 .- 1076-1551. ; 19, s. 314-323
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus is sometimes isolated from the airways during acute exacerbations of chronic obstructive pulmonary disease (COPD) but more commonly recognized as a cause of ventilator-associated pneumonia (VAP). Antimicrobial proteins, among them midkine (MK), are an important part of innate immunity in the airways. In this study, the levels and possible processing of MK in relation to S. aureus infection of the airways were investigated, comparing COPD and VAP, thus comparing a state of disease with preceding chronic inflammation and remodeling (COPD) with acute inflammation (i.e. VAP). MK was detected in the small airways and alveoli of COPD lung tissue but less so in normal lung tissue. MK at below micromolar concentrations killed S. aureus in vitro. Proteolytic processing of MK by the staphylococcal metalloprotease AL but not cysteine protease SA, resulted in impaired bactericidal activity. Degradation was foremost seen in the COOH-terminal portion of the molecule that harbors high bactericidal activity. In addition, MK was detected in sputum from patients suffering from VAP caused by S. aureus but less so in sputum from COPD-exacerbations associated with the same bacterium. Recombinant MK was degraded more rapidly in sputum from the COPD patients than from the VAP patients and a greater proteolytic activity in COPD sputum was confirmed by zymography. Taken together, proteases of both bacteria and the host contribute to degradation of the antibacterial protein MK, resulting in an impaired defense of the airways, in particular in COPD where the state of chronic inflammation could be of importance.
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| 18. |
- Mohammad, Majd, et al.
(författare)
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RAGE Deficiency Impairs Bacterial Clearance in Murine Staphylococcal Sepsis, but Has No Significant Impact on Staphylococcal Septic Arthritis.
- 2016
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 11:12
-
Tidskriftsartikel (refereegranskat)abstract
- Septic arthritis is a serious joint disease often caused by Staphylococcus aureus (S. aureus). Receptor for Advanced Glycation End products (RAGE) has an important role in several infections. We sought to investigate the role of RAGE in staphylococcal septic arthritis and sepsis in mice.Wild-type (WT) and RAGE deficient (RAGE-/-) mice were intra-articularly or intravenously inoculated with an arthritic or septic dose of S. aureus LS-1 strain. Clinical arthritis, weight development and mortality were monitored for 14 days. Serum levels of cytokines, kidney bacterial loads as well as micro-CT and histopathology of the joints were assessed.RAGE-/- mice with septic arthritis had significantly lower IL-17A and higher bone mineral density (BMD) compared to the control group. However, no significant differences between the groups were observed regarding the weight loss, the severity and frequency of arthritis, and bacterial loads in the kidneys. In mice with sepsis, the overall mortality rate was similar in RAGE-/- (39%) and in WT mice (45%). However, RAGE-/- mice with sepsis had significantly higher bacterial load in their kidneys compared to the WT controls. In line with data from hematogenous S. aureus arthritis, RAGE deficiency had no impact on arthritis severity in local joint infection.Our results indicate that lack of RAGE has no significant impact on septic arthritis. However, RAGE-/- mice had significantly higher BMD compared to WT mice, which coincided with lower IL-17A in RAGE-/- mice. In sepsis, RAGE deficiency impairs bacterial kidney clearance.
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| 19. |
- Na, Manli, et al.
(författare)
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Deficiency of the complement component 3 but not factor B aggravates Staphylococcus aureus septic arthritis in mice.
- 2016
-
Ingår i: Infection and immunity. - 1098-5522. ; 84:4, s. 930-939
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Tidskriftsartikel (refereegranskat)abstract
- The complement system plays an essential role in the innate immune response and protection against bacterial infections. However, detailed knowledge regarding the role of complement in Staphylococcus aureus (S. aureus) septic arthritis is still largely missing. In this study, we elucidated the role of selected complement proteins in S. aureus septic arthritis. Mice lacking the complement component 3 (C3(-/-)), complement factor B (fB(-/-)), receptor for C3 derived anaphylatoxin C3a (C3aR(-/-)) and wild-type (WT) control mice were intravenously or intraarticularly inoculated with Staphylococcus aureus Newman strain. The clinical course of septic arthritis as well as histopathological and radiological changes in joints were assessed. After intravenous inoculation, arthritis severity and frequency was significantly higher in C3(-/-) mice compared to WT controls, whereas fB(-/-) mice displayed intermediate arthritis severity and frequency. This was in accordance with both histopathological and radiological findings. C3 but not fB deficiency was associated with larger weight loss, more frequent kidney abscesses, as well as higher bacterial burden in kidneys. S. aureus opsonised with C3(-/-) sera displayed decreased uptake by mouse peritoneal macrophages compared with bacteria opsonised with WT or fB(-/-) sera. C3aR deficiency had no effect on the course of hematogenous S. aureus septic arthritis. We conclude that C3 deficiency increases the susceptibility to hematogenous S. aureus septic arthritis and impairs host bacterial clearance, conceivably due to diminished opsonisation and phagocytosis of S. aureus.
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| 20. |
- Persson, Hans Lennart, et al.
(författare)
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Alveolar macrophages from patients with tuberculosis exhibit reduced capacity of restricting growth of Mycobacterium tuberculosis: a pilot study of vitamin D stimulation in vitro
- 2013
-
Ingår i: Microbiology Discovery. - United Kingdom : Herbert Publications PVT LTD. - 2052-6180. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The role of vitamin D supplementation as adjuvant treatment of tuberculosis (TB) has lately attracted increasing interest. Our aim was to investigate the capacity of alveolar macrophages (AMs) from patients with or without exposure to TB to control intracellular growth of virulent Mycobacterium tuberculosis (Mtb). Methods: AMs were freshly harvested from the bronchoalveolar lavage fluid of 7 patients with a history of TB (4 patients with previous TB and 3 patients with current TB) and 4 non-TB subjects. The H37Rv strain, genetically modified to express Vibrio harveyi luciferase, was used to determine the growth of Mtb by luminometry in the AMs from study subjects. Cytokine levels in culture supernatants were determined using a flow cytometry-based bead array technique. Results: AMs from patients with a TB history were less efficient in restricting Mtb growth. Stimulation with 100 nM1, 25-dihydroxyvitamin D (1,25D3) did not significantly influence the capacity of AMs from any study subjects to control the infection. Out of the cytokines evaluated (TNF-α, IL-1β, IL-10 and IL-12p40) only TNF-α demonstrated detectable levels in culture supernatants, but did not respond to stimulation with 1,25D3. Conclusions: We conclude that AMs of TB-patients show reduced ability to control mycobacterial growth in vitro, and, that AMs in this pilot study do no respond to 1, 25D3-stimulation. The former observation supports the concept that innate immunity is crucial for the control of TB infection.
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| 21. |
- Sundqvist, Martina, et al.
(författare)
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Galectin-3 type-C self-association on neutrophil surfaces; The carbohydrate recognition domain regulates cell function
- 2018
-
Ingår i: Journal of Leukocyte Biology. - 0741-5400. ; 103:2, s. 341-353
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Tidskriftsartikel (refereegranskat)abstract
- Galectin-3 is an endogenous β-galactoside-binding lectin comprising a carbohydrate recognition domain (CRD) linked to a collagen-like N-domain. Both domains are required for galectin-3 to induce cellular effects; a C-terminal fragment of galectin-3, galectin-3C, containing the CRD but lacking the N-domain, binds cell surface glycoconjugates but does not induce cellular effects since cross-linking promoted by the N-domain is thought to be required. Instead, galectin-3C is proposed to antagonize the effects of galectin-3 by competing for binding sites. The aim of this study was to investigate the effects of galectin-3C on galectin-3 interactions with human neutrophils. Recombinant galectin-3C inhibited galectin-3-induced production of reactive oxygen species in primed neutrophils. Surprisingly, this inhibition was not due to competitive inhibition of galectin-3 binding to the cells. In contrast, galectin-3C potentiated galectin-3 binding, in line with emerging evidence that galectin-3 can aggregate not only through the N-domain but also through the CRD. The cell surface interaction between galectin-3C and galectin-3 was corroborated by colocalization of fluorescently labeled galectin-3 and galectin-3C. Galectin-3C can be generated in vivo through cleavage of galectin-3 by proteases. Indeed, in circulation, galectin-3 and galectin-3C were both attached to the cell surface of neutrophils, which displayed great capacity to bind additional galectin-3 and galectin-3C. In conclusion, galectin-3C enhances galectin-3 binding to neutrophils by nonactivating type-C self-association, in parallel to inhibiting neutrophil activation by galectin-3 (induced by type-N self-association). This implicates type-C self-association as a termination system for galectin-3-induced cell activation, with the purpose of avoiding oxidant-dependent tissue damage. ©2018 Society for Leukocyte Biology
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| 22. |
- Sundqvist, Martina, et al.
(författare)
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Severe chronic non-bacterial osteomyelitis in combination with total MPO deficiency and responsiveness to TNFα inhibition
- 2023
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Ingår i: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- We describe a female patient suffering from severe chronic non-bacterial osteomyelitis (CNO) with systemic inflammation and advanced malnutrition and complete deficiency of myeloperoxidase (MPO). CNO is a rare autoinflammatory bone disorder associated with dysregulation of the innate immune system. MPO deficiency is a genetic disorder with partial or complete absence of the phagocyte peroxidase MPO. MPO deficiency has no established clinical phenotype but reports indicate increased susceptibility to infection and chronic inflammation. The patient’s symptoms began at 10 years of age with pain in the thighs, systemic inflammation and malnutrition. She was diagnosed with CNO at 14 years of age. Treatment with nonsteroidal anti-inflammatory drugs, corticosteroids, bisphosphonates or IL1-receptor antagonists (anakinra) did not relieve the symptoms. However, the patient responded instantly and recovered from her clinical symptoms when treated with TNFα blockade (adalimumab). Three years after treatment initiation adalimumab was withdrawn, resulting in rapid symptom recurrence. When reintroducing adalimumab, the patient promptly responded and went into remission. In addition to clinical and laboratory profiles, neutrophil functions (reactive oxygen species, ROS; neutrophil extracellular traps, NETs; degranulation; apoptosis; elastase activity) were investigated both in a highly inflammatory state (without treatment) and in remission (on treatment). At diagnosis, neither IL1β, IL6, nor TNFα was significantly elevated in serum, but since TNFα blockade terminated the inflammatory symptoms, the disease was likely TNFα-driven. All neutrophil parameters were normal both during treatment and treatment withdrawal, except for MPO-dependent intracellular ROS- and NET formation. The role of total MPO deficiency for disease etiology and severity is discussed.
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| 23. |
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| 24. |
- Welin, Amanda, 1983, et al.
(författare)
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CFP-10 from Mycobacterium tuberculosis Selectively Activates Human Neutrophils through a Pertussis Toxin-Sensitive Chemotactic Receptor.
- 2015
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Ingår i: Infection and immunity. - 1098-5522. ; 83:1, s. 205-213
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Tidskriftsartikel (refereegranskat)abstract
- Upon infection with Mycobacterium tuberculosis, neutrophils are massively recruited to the lungs, but the role of these cells in combating the infection is poorly understood. Through a type VII secretion system, M. tuberculosis releases a heterodimeric protein complex, containing a 6-kDa early secreted antigenic target (ESAT-6) and a 10-kDa culture filtrate protein (CFP-10), that is essential for virulence. Whereas the ESAT-6 component possesses multiple virulence-related activities, no direct biological activity of CFP-10 has been shown, and CFP-10 has been described as a chaperone protein for ESAT-6. We here show that the ESAT-6:CFP-10 complex induces a transient release of Ca(2+) from intracellular stores in human neutrophils. Surprisingly, CFP-10 rather than ESAT-6 was responsible for triggering the Ca(2+) response, in a pertussis toxin-sensitive manner, suggesting the involvement of a G-protein-coupled receptor. In line with this, the response was accompanied by neutrophil chemotaxis and activation of the superoxide-producing NADPH-oxidase. Neutrophils were unique among leukocytes in responding to CFP-10, as monocytes and lymphocytes failed to produce a Ca(2+) signal upon stimulation with the M. tuberculosis protein. Hence, CFP-10 may contribute specifically to neutrophil recruitment and activation during M. tuberculosis infection, representing a novel biological role for CFP-10 in the ESAT-6:CFP-10 complex, beyond the previously described chaperone function.
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| 25. |
- Welin, Amanda, 1983-, et al.
(författare)
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Imaging Flow Cytometry of Legionella-Containing Vacuoles in Intact and Homogenized Wild-Type and Mutant Dictyostelium
- 2023
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Ingår i: Spectral and Imaging Cytometry. - : Humana Press. - 9781071630198 - 9781071630204 ; , s. 63-85
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Bokkapitel (refereegranskat)abstract
- The causative agent of a severe pneumonia termed "Legionnaires' disease", Legionella pneumophila, replicates within protozoan and mammalian phagocytes in a specialized intracellular compartment called the Legionella-containing vacuole (LCV). This compartment does not fuse with bactericidal lysosomes but communicates extensively with several cellular vesicle trafficking pathways and eventually associates tightly with the endoplasmic reticulum. In order to comprehend in detail the complex process of LCV formation, the identification and kinetic analysis of cellular trafficking pathway markers on the pathogen vacuole are crucial. This chapter describes imaging flow cytometry (IFC)-based methods for the objective, quantitative and high-throughput analysis of different fluorescently tagged proteins or probes on the LCV. To this end, we use the haploid amoeba Dictyostelium discoideum as an infection model for L. pneumophila, to analyze either fixed intact infected host cells or LCVs from homogenized amoebae. Parental strains and isogenic mutant amoebae are compared in order to determine the contribution of a specific host factor to LCV formation. The amoebae simultaneously produce two different fluorescently tagged probes enabling tandem quantification of two LCV markers in intact amoebae or the identification of LCVs using one probe and quantification of the other probe in host cell homogenates. The IFC approach allows rapid generation of statistically robust data from thousands of pathogen vacuoles and can be applied to other infection models.
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| 26. |
- Welin, Amanda, 1983, et al.
(författare)
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Inside or outside the phagosome? The controversy of the intracellular localization of Mycobacterium tuberculosis.
- 2012
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Ingår i: Tuberculosis (Edinburgh, Scotland). - : Elsevier BV. - 1873-281X .- 1472-9792. ; 92:2, s. 113-20
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Forskningsöversikt (refereegranskat)abstract
- The localization of Mycobacterium tuberculosis (Mtb) inside the macrophage has been a matter of debate in recent years. Upon inhalation, the bacterium is taken up into macrophage phagosomes, which are manipulated by the bacterium. Subsequent translocation of the bacilli into the cytosol has been observed by several groups, while others fail to observe this phenomenon. Here, we review the available literature in favour of and against this idea, and scrutinize the existing data on how human macrophages control Mtb infection, relating this to the robustness of the host cell. We conclude that both phagosomal maturation inhibition and escape from the phagosome are part of the greater infection strategy of Mtb. The balance between the host cell and the infecting bacterium is an important factor in determining the outcome of infection as well as whether phagosomal escape occurs and can be captured.
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| 27. |
- Welin, Amanda, 1983-
(författare)
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Survival strategies of Mycobacterium tuberculosis inside the human macrophage
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mycobacterium tuberculosis (Mtb) is the bacterium responsible for tuberculosis (TB). For decades, it was believed that TB was a disease of the past, but the onset of the HIV epidemic resulting in a greatly increased number of TB cases, the emergence of antibiotic resistant Mtb strains, and the relative ineffectiveness of the BCG vaccine have put TB back on the agenda. With almost two million people being killed by TB each year, the World Health Organization has declared it a global emergency. TB is an especially big issue in low-income countries, where crowded living conditions accelerates spread of the disease, and where access to health care and medication is problematic. Mtb spreads by aerosol and infects its host through the airways. The bacterium is phagocytosed by resident macrophages in the lung, and when successful is able to replicate inside these cells, which are actually designed to kill invading microbes. Mtb is able to evade macrophage responses in part by inhibiting the fusion between the phagosome in which it resides and bactericidal lysosomes, as well as by dampening the acidification of the vacuole. The initial macrophage infection results in a pro-inflammatory response and the recruitment of other cells of the innate and adaptive immune systems, giving rise to the hallmark of Mtb infection – the granuloma. It is believed that in up to 50 % of exposed individuals, however, the infection is cleared without the involvement of the adaptive immune system, indicating that the innate immune system may be able to control or clear the infection if activated appropriately. This thesis focuses on the interaction between the host macrophage and Mtb, aiming to understand some of the mechanisms employed by the bacterium to evade macrophage responses to enable replication and spread to new host cells. Furthermore, mechanisms used by the macrophage to keep the infection under control were studied, and a method that could be used to measure the replication of the bacilli inside macrophages in vitro in an efficient way was developed. We found that a mycobacterial glycoprotein, mannose-capped lipoarabinomannan (ManLAM), which is shed from the bacilli during phagocytosis by macrophages, integrates into membrane raft domains of the host cell membrane via its GPI anchor. This integration leads to an inhibition of phagosomal maturation. Subsequently, we developed a luciferase-based method by which intracellular replication of Mtb as well as viability of the host macrophage could be measured in a rapid, inexpensive and quantitative way in a 96-well plate. This method could be used for drug screening as well as for studying the different host and bacterial factors that influence the growth of Mtb inside the host cell. Using this method, we discovered that infection of macrophages with Mtb at a low multiplicity of infection (MOI) led to effective control of bacterial growth by the cell, and that this was dependent on functional lysosomal proteases as well as phagosomal acidification. However, we found no correlation between controlled bacterial growth and the translocation of late endosomal membrane proteins to the phagosome, showing that these markers are poor indicators of phagosomal functionality. Furthermore, we discovered that infection of macrophages with Mtb at a higher MOI led to replication of the bacilli accompanied by host cell death within a few days. We characterized this cell death, and concluded that when replication of Mtb inside macrophages reaches a certain threshold and the bacteria secrete a protein termed ESAT-6, necrotic cell death of the host cell occurs. However, although the bacilli activated inflammasome complexes in the host cell and IL-1β was secreted during infection of macrophages, Mtb infection did not induce either of the recently characterized inflammasome-related cell death types pyroptosis or pyronecrosis. Thus, we have elucidated some of the strategies that Mtb uses to be able to survive and replicate inside the macrophage and spread to new cells, as well as studied the conditions under which the host cell is able to control infection. This knowledge could be used in the future for developing drugs that boost the innate immune system or targets bacterial virulence factors in the macrophage.
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| 28. |
- Welin, Amanda, 1983, et al.
(författare)
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The Human Neutrophil Subsets Defined by the Presence or Absence of OLFM4 Both Transmigrate into Tissue In Vivo and Give Rise to Distinct NETs In Vitro.
- 2013
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 8:7
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil heterogeneity was described decades ago, but it could not be elucidated at the time whether the existence of different neutrophil subsets had any biological relevance. It has been corroborated in recent years that neutrophil subsets, defined by differential expression of various markers, are indeed present in human blood, calling for renewed attention to this question. The expression of the granule protein olfactomedin 4 (OLFM4) has been suggested to define two such neutrophil subsets. We confirm the simultaneous presence of one OLFM4-positive and one OLFM4-negative neutrophil subpopulation as well as the localization of the protein to specific granules. In vitro, these neutrophil subsets displayed equal tendency to undergo apoptosis and phagocytose bacteria. In addition, the subpopulations were recruited equally to inflammatory sites in vivo, and this was true both in an experimental model of acute inflammation and in naturally occurring pathological joint inflammation. In line with its subcellular localization, only limited OLFM4 release was seen upon in vivo transmigration, and release through conventional degranulation required strong secretagogues. However, extracellular release of OLFM4 could be achieved upon formation of neutrophil extracellular traps (NETs) where it was detected only in a subset of the NETs. Although we were unable to demonstrate any functional differences between the OLFM4-defined subsets, our data show that different neutrophil subsets are present in inflamed tissue in vivo. Furthermore, we demonstrate NETs characterized by different markers for the first time, and our results open up for functions of OLFM4 itself in the extracellular space through exposure in NETs.
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| 29. |
- Winther, Malene, et al.
(författare)
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A neutrophil inhibitory pepducin derived from FPR1 expected to target FPR1 signaling hijacks the closely related FPR2 instead
- 2015
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Ingår i: Febs Letters. - : Wiley. - 0014-5793. ; 589:15, s. 1832-1839
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Tidskriftsartikel (refereegranskat)abstract
- Pepducins constitute a unique class of G-protein coupled receptor (GPCR) modulating lipopeptides. Pepducins with inhibitory effects on neutrophils could potentially be developed into anti-inflammatory pharmaceuticals. A pepducin with a peptide sequence identical to the third intracellular loop of FPR1 was found to inhibit neutrophil functions including granule mobilization and superoxide production. This FPR1-derived pepducin selectively inhibited signaling and cellular responses through FPR2, but not FPR1 as expected. Binding to the neutrophil surface of a conventional FPR2 agonist is also inhibited. The fatty acid is essential for inhibition and pepducins with shorter peptides lose in potency. In summary, a pepducin designed to target FPR1 was found to hijack FPR2 and potently inhibit neutrophil functions. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
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