| 1. |
- Forsberg, Maria, et al.
(författare)
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Differential effects of invasion by and phagocytosis of Salmonella typhimurium on apoptosis in human macrophages : potential role of Rho–GTPases and Akt
- 2003
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Ingår i: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 0741-5400 .- 1938-3673. ; 74:4, s. 620-629
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Tidskriftsartikel (refereegranskat)abstract
- In addition to direct activation of caspase-1 and induction of apoptosis by SipB, invasive Salmonella stimulates multiple signaling pathways that are key regulators of host cell survival. Nevertheless, little is known about the relative contributions of these pathways to Salmonella-mediated death of macrophages. We studied human monocytic U937 cells and found that apoptosis was induced by invading wild-type Salmonella typhimurium but not by phagocytosed, serum-opsonized, noninvasive Salmonella mutants. Pretreating U937 cells with inhibitors of tyrosine kinases or phosphatidylinositol-3 kinase (PI-3K) completely blocked phagocytosis of opsonized Salmonella mutants but did not affect invasion by wild-type Salmonella or the apoptosis caused by invasion. However, pretreatment with GGTI-298, a geranylgeranyltransferase-1 inhibitor that prevents prenylation of Cdc42 and Rac1, suppressed Salmonella-induced apoptosis by ∼70%. Transduction of Tat fusion constructs containing dominant-negative Cdc42 or Rac1 significantly inhibited Salmonella-induced cell death, indicating that the cytotoxicity of Salmonella requires activation of Cdc42 and Rac. In contrast to phagocytosis of opsonized bacteria, invasion by S. typhimurium stimulated Cdc42 and Rac1, regardless of the activities of tyrosine- or PI-3K. Moreover, Salmonella infection activated Akt protein in a tyrosine-kinase or PI-3K-dependent manner, and a reduced expression of Akt by antisense transfection rendered the cells more sensitive to apoptosis induced by opsonized Salmonella. These results indicate that direct activation of Cdc42 and Rac1 by invasive Salmonella is a prerequisite of Salmonella-mediated death of U937 cells, whereas the simultaneous activation of Akt by tyrosine kinase and PI-3K during receptor-mediated phagocytosis protects cells from apoptosis.
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| 2. |
- Serrander, Lena, et al.
(författare)
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Particles binding β2-integrins mediate intracellular production of oxidative metabolites in human neutrophils independently of phagocytosis
- 1999
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Ingår i: Biochimica et Biophysica Acta. Molecular Cell Research. - 0167-4889 .- 1879-2596. ; 1452:2, s. 133-144
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Tidskriftsartikel (refereegranskat)abstract
- Complement-opsonised particles are readily ingested by human neutrophils through a complement receptor-mediated process leading to phagolysosome fusion and production of oxidative metabolites. To investigate the complement receptor 3 (CR3)-associated signal system involved, cells were challenged with protein A-positive, heat-killed Staphylococcus aureus to which antibodies with specificity for the subunits of the β2-integrins, i.e. anti-CD11b (the α subunit of CR3) and anti-CD18 (the β subunit of CR3), were bound through their Fc moiety. Despite not being ingested by the neutrophils, the surface associated anti-CD18- and anti-CD11b-coated particles were able to activate the neutrophil NADPH-oxidase. Also anti-CD11a- (the α subunit of LFA-1) and to a lesser extent anti-CD11c- (the α subunit of CR4) coated particles were able to trigger the NADPH-oxidase. The NADPH-oxidase was activated without extracellular release of reactive oxygen species. The activity was inhibited by cytochalasin B, suggesting a necessary role for the cytoskeleton in the signalling pathway that activates the oxidase. We show that particle-mediated cross-linking of β2-integrins on the neutrophil surface initiates a signalling cascade, involving cytoskeletal rearrangements, leading to an activation of the NADPH-oxidase without phagosome formation or extracellular release of reactive oxygen species.
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| 3. |
- Abate Waktola, Ebba Abate, et al.
(författare)
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Polymorphisms in CARD8 and NLRP3 are associated with extrapulmonary TB and poor clinical outcome in active TB in Ethiopia
- 2019
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Innate immunity is a first line defense against Mycobacterium tuberculosis infection where inflammasome activation and secretion of the pro-inflammatory cytokine IL-1beta, plays a major role. Thus, genetic polymorphisms in innate immunity-related genes such as CARD8 and NLRP3 may contribute to the understanding of why most exposed individuals do not develop infection. Our aim was to investigate the association between polymorphisms in CARD8 and NLRP3 and active tuberculosis (TB) as well as their relationship to treatment outcome in a high-endemic setting for TB. Polymorphisms in CARD8 (C10X) and NLRP3 (Q705K) were analysed in 1190 TB patients and 1990 healthy donors (HD). There was a significant association between homozygotes in the CARD8 polymorphism and extrapulmonary TB (EPTB), which was not the case for pulmonary TB or HDs. Among TB-patients, there was an association between poor treatment outcome and the NLRP3 (Q705K) polymorphism. Our study shows that inflammasome polymorphisms are associated with EPTB and poor clinical outcome in active TB in Ethiopia. The practical implications and determining causal relationships on a mechanistic level needs further study.
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| 4. |
- Andersson, Anna-Maria, et al.
(författare)
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Efferocytosis of Apoptotic Neutrophils Enhances Control of Mycobacterium tuberculosis in HIV-Coinfected Macrophages in a Myeloperoxidase-Dependent Manner
- 2020
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Ingår i: Journal of Innate Immunity. - : KARGER. - 1662-811X .- 1662-8128. ; 12:3, s. 235-247
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Tidskriftsartikel (refereegranskat)abstract
- Tuberculosis remains a big threat, with 1.6 million deaths in 2017, including 0.3 million deaths among patients with HIV. The risk of developing active disease increases considerably during an HIV coinfection. Alveolar macrophages are the first immune cells to encounter the causative agent Mycobacterium tuberculosis, but during the granuloma formation other cells are recruited in order to combat the bacteria. Here, we have investigated the effect of efferocytosis of apoptotic neutrophils by M. tuberculosis and HIV-coinfected macrophages in a human in vitro system. We found that the apo-ptotic neutrophils enhanced the control of M. tuberculosis in single and HIV-coinfected macrophages, and that this was dependent on myeloperoxidase (MPO) and reactive oxygen species in an autophagy-independent manner. We show that MPO remains active in the apoptotic neutrophils and can be harnessed by infected macrophages. In addition, MPO inhibition removed the suppression in M. tuberculosis growth caused by the apoptotic neutrophils. Antimycobacterial components from apoptotic neutrophils could thus increase the microbicidal activity of macrophages during an M. tuberculosis/HIV coinfection. This cooperation between innate immune cells could thereby be a way to compensate for the impaired adaptive immunity against M. tuberculosis seen during a concurrent HIV infection.
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| 5. |
- Andersson, Anna-Maria, 1990-
(författare)
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Mycobacterium tuberculosis and HIV coinfection : Effects on innate immunity and strategies to boost the immune response
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tuberculosis (TB) still remains a big threat today, being the leading cause of death by a single infectious agent. The TB epidemic is fueled by HIV along with the increasing drug-resistance which prolongs the already long treatment duration and decreases the success rate for curing TB. In most cases an infection results in latency but HIV patients have a 20-30 times higher risk of developing active TB. There are around 36.9 million people living with HIV globally, with the highest burden in Africa. Although there are effective treatments against the disease, there is no cure for AIDS and the availability of the lifelong treatment is limited in low-income countries were the burden is highest. HIV infection causes an immunodeficiency characterized by the progressive loss of CD4 T cells which increases the risk of opportunistic infections, and infection by Mycobacterium tuberculosis (Mtb), the causative agent of TB. Mtb spreads through aerosols from one person with active tuberculosis to a healthy person. Upon inhalation the bacteria are phagocytosed by alveolar macrophages that secrete cytokines and chemokines to recruit more cells, such as dendritic cells, macrophages and lymphocytes, leading to the formation of a granuloma. During a single TB infection the bacteria are usually contained within the granuloma, but HIV can disrupt the stable granuloma, causing a rupture and dissemination of Mtb. This inflammatory site is also beneficial to HIV since it promotes replication of the virus within infected cells. HIV and Mtb are two successful intracellular pathogens able to avoid immune defense mechanisms both of the innate and adaptive immunity in order to persist and replicate. Their virulence factors can manipulate or inhibit cell signaling, phagosome maturation, autophagy, ROS production, apoptosis and antigen presentation, to promote survival. Boosting of immune defenses with host-directed therapies (HDT) has been proposed as a treatment strategy against TB, either alone or adjunctive to the current regimen.In this thesis, ways to boost the innate immune responses in Mtb and HIV coinfected macrophages were investigated, along with studies of the effect of HIV on Mtb antigen presentation in coinfected dendritic cells. The initial hypothesis was that autophagy induction through inhibition of mammalian target of rapamycin (mTOR) could suppress Mtb growth in HIV coinfected macrophages. However, during a low grade infection, autophagy induction increased Mtb replication due to a decreased autophagic flux and acidification of Mtb phagosomes. A general autophagic flux was induced, although not localized to the Mtb phagosomes, thus not inducing a xenophagy (autophagy of intracellular pathogens). Other ways of inducing autophagy or boosting the response in coinfected macrophages might be more beneficial and therefore the effect of efferocytosis was investigated. Uptake of apoptotic neutrophils by coinfected macrophages did not induce autophagy but enhanced the control of Mtb by other means. Upon efferocytosis, the macrophages acquired active myeloperoxidase (MPO) from the neutrophils that suppressed Mtb growth. The coinfected macrophages also produced more ROS after efferocytosis. The inhibition of Mtb growth could thus be mediated by MPO and the increased ROS production either directly or indirectly.The possibility to boost the innate immunity could prove to be important during an HIV coinfection, when the adaptive immunity is deficient. In addition to the well-known decline in CD4 T cells during the course of HIV progression, we found that HIV infection of dendritic cells inhibited antigen presentation by suppressing the expression of HLA-DR and co-stimulatory molecules on coinfected dendritic cells. Furthermore, HIV reduced secretion of pro-inflammatory cytokines and suppressed antigen processing through inhibition of autophagy. This impaired antigen presentation in coinfected dendritic cells resulted in a decreased activation and response of Mtb-specific CD4 T cells.In conclusion, this thesis shows how HIV can manipulate antigen presentation in Mtb coinfected dendritic cells and subsequently inhibit the adaptive immune response. It also contributes to insights on how efferocytosis of apoptotic neutrophils can boost the innate immune responses during coinfection. Lastly, autophagy induction through mTOR inhibition does not enhance protection against TB. Induction of autophagy should therefore be handled with care, particularly during HIV coinfection.
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| 6. |
- Andersson, Henrik, et al.
(författare)
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Apoptotic neutrophils augment the inflammatory response to Mycobacterium tuberculosis infection in human macrophages
- 2014
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Ingår i: PLOS ONE. - : PLOS. - 1932-6203. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- Macrophages in the lung are the primary cells being infected by Mycobacterium tuberculosis (Mtb) during the initial manifestation of tuberculosis. Since the adaptive immune response to Mtb is delayed, innate immune cells such as macrophages and neutrophils mount the early immune protection against this intracellular pathogen. Neutrophils are short-lived cells and removal of apoptotic cells by resident macrophages is a key event in the resolution of inflammation and tissue repair. Since anti-inflammatory activity is not compatible with effective immunity to intracellular pathogens, we therefore investigated how uptake of apoptotic neutrophils modulates the function of Mtb-activated human macrophages. We show that Mtb infection exerts a potent proinflammatory activation of human macrophages with enhanced gene activation and release of proinflammatory cytokines and that this response was augmented by apoptotic neutrophils. The enhanced macrophage response is linked to apoptotic neutrophil-driven activation of the NLRP3 inflammasome and subsequent IL-1β signalling. We also demonstrate that apoptotic neutrophils not only modulate the inflammatory response, but also enhance the capacity of infected macrophages to control intracellular growth of virulent Mtb. Taken together, these results suggest a novel role for apoptotic neutrophils in the modulation of the macrophage-dependent inflammatory response contributing to the early control of Mtb infection.
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| 7. |
- Andersson, Kerstin, et al.
(författare)
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Yersinia pseudotuberculosis-induced calcium signaling in neutrophils is blocked by the virulence effector YopH
- 1999
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 67:5, s. 2567-2574
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Tidskriftsartikel (refereegranskat)abstract
- Pathogenic species of the genus Yersinia evade the bactericidal functions of phagocytes. This evasion is mediated through their virulence effectors, Yops, which act within target cells. In this study we investigated the effect of Yersinia pseudotuberculosis on Ca 2+ signaling in polymorphonuclear neutrophils. The intracellular free calcium concentration in single adherent human neutrophils was monitored during bacterial infection and, in parallel, the encounter between the bacteria and cells was observed. When a plasmid-cured strain was used for infection, adherence of a single bacterium to the cellular surface induced a β 1 integrin-dependent transient increase in the intracellular concentration of free calcium. This was, however, not seen with Yop-expressing wild-type bacteria, which adhered to the cell surface without generating any Ca 2+ signal. Importantly, the overall Ca 2+ homeostasis was not affected by the wild-type strain; the Ca 2+ signal mediated by the G-protein-coupled formyl-methionyl-leucyl- phenylalanine receptor was still functioning. Hence, the blocking effect was restricted to certain receptors and their signaling pathways. The use of different Yop mutant strains revealed that the protein tyrosine phosphatase YopH was responsible for the inhibition. This virulence determinant has previously been implicated in very rapid Yersinia-mediated effects on target cells as the key effector in the blockage of phagocytic uptake. The present finding, that Y. pseudotuberculosis, via YopH, specifically inhibits a self- induced immediate-early Ca 2+ signal in neutrophils, offers more-detailed information concerning the effectiveness of this virulence effector and implies an effect on Ca 2+-dependent, downstream signals.
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| 8. |
- Blomgran, Robert, et al.
(författare)
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Common Genetic Variations in the NALP3 Inflammasome Are Associated with Delayed Apoptosis of Human Neutrophils
- 2012
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Ingår i: PLOS ONE. - San Francisco, USA : Public Library of Science. - 1932-6203. ; 7:3
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neutrophils are key-players in the innate host defense and their programmed cell death and removal are essential for efficient resolution of inflammation. These cells recognize a variety of pathogens, and the NOD-like receptors (NLRs) have been suggested as intracellular sensors of microbial components and cell injury/stress. Some NLR will upon activation form multi-protein complexes termed inflammasomes that result in IL-1 beta production. NLR mutations are associated with auto-inflammatory syndromes, and our previous data propose NLRP3 (Q705K)/CARD-8 (C10X) polymorphisms to contribute to increased risk and severity of inflammatory disease by acting as genetic susceptibility factors. These gene products are components of the NALP3 inflammasome, and approximately 6.5% of the Swedish population are heterozygote carriers of these combined gene variants. Since patients carrying the Q705K/C10X polymorphisms display leukocytosis, the aim of the present study was to find out whether the inflammatory phenotype was related to dysfunctional apoptosis and impaired clearance of neutrophils by macrophages. less thanbrgreater than less thanbrgreater thanMethods and Findings: Patients carrying the Q705K/C10X polymorphisms displayed significantly delayed spontaneous as well as microbe-induced apoptosis compared to matched controls. Western blotting revealed increased levels and phosphorylation of Akt and Mcl-1 in the patients neutrophils. In contrast to macrophages from healthy controls, macrophages from the patients produced lower amounts of TNF; suggesting impaired macrophage clearance response. less thanbrgreater than less thanbrgreater thanConclusions: The Q705K/C10X polymorphisms are associated with delayed apoptosis of neutrophils. These findings are explained by altered involvement of different regulators of apoptosis, resulting in an anti-apoptotic profile. Moreover, the macrophage response to ingestion of microbe-induced apoptotic neutrophils is altered in the patients. Taken together, the patients display impaired turnover and clearance of apoptotic neutrophils, pointing towards a dysregulated innate immune response that influences the resolution of inflammation. The future challenge is to understand how microbes affect the activation of inflammasomes, and why this interaction will develop into severe inflammatory disease in certain individuals.
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| 9. |
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| 10. |
- Borgquist, Signe, et al.
(författare)
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Oestrogen receptors alpha and beta show different associations to clinicopathological parameters and their co-expression might predict a better response to endocrine treatment in breast cancer.
- 2008
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Ingår i: Journal of Clinical Pathology. - : BMJ. - 1472-4146 .- 0021-9746. ; 61:2, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: The majority of all breast cancers are hormone responsive, traditionally defined by the expression of oestrogen receptor (ER) alpha and/or progesterone receptors. In contrast to ERalpha, the clinical significance of the relatively recently identified ERbeta is still unclear. This study aimed to define the relationship between ERbeta and clinicopathological parameters in a mixed cohort of breast cancer and, furthermore, to investigate the impact of ERbeta expression on disease outcome. METHODS: The immunohistochemical expression of ERalpha and ERbeta was analysed in tissue microarrays containing a total number of 512 tumours with all incident breast cancers diagnosed at the Malmö University Hospital between 1988 and 1992. RESULTS: 78% of the tumours were ERalpha positive and 50% were ERbeta positive. ERbeta correlated positively with ERalpha (p = 0.001). In contrast to ERalpha, ERbeta was not associated with any important clinicopathological variables. Furthermore, no overall prognostic significance could be demonstrated for ERbeta. In the ERalpha-positive subgroup, however, a low expression of ERbeta correlated with a decreased disease-free survival in patients receiving endocrine treatment (p = 0.003). CONCLUSIONS: Although interrelated, ERalpha and ERbeta seem to be differentially associated to clinicopathological parameters, and this would support the fact that they might have different functions in vivo. Furthermore, ERbeta might be a predictive marker of response to endocrine therapy, although this needs to be confirmed in additional studies, preferably randomised trials.
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