| 1. |
- Singh, Birendra, et al.
(författare)
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A fine-tuned interaction between the trimeric autotransporter Haemophilus surface fibrils and vitronectin leads to serum resistance and adherence to respiratory epithelial cells.
- 2014
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Ingår i: Infection and Immunity. - 1098-5522. ; 82:6, s. 2378-2389
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Tidskriftsartikel (refereegranskat)abstract
- Haemophilus influenzae type b (Hib) escapes the host immune system by recruitment of the complement regulator vitronectin that inhibits the formation of the membrane attack complex (MAC) by inhibiting C5b-C7 complex formation and C9 polymerization. We previously reported that Hib acquires vitronectin at the surface by using Haemophilus surface fibrils (Hsf). Here we studied in detail the interaction between Hsf and vitronectin and its role in inhibition of MAC formation and invasion of lung epithelial cells. The vitronectin-binding region of Hsf was defined at the N-terminal comprising amino acids Hsf 429-652. Moreover, the Hsf recognition site on vitronectin consisted of the C-terminal amino acids 352-374. H. influenzae was killed more rapidly in vitronectin-depleted serum when compared to normal human serum (NHS), and an increased MAC deposition was observed at the surface of an Hsf-deficient H. influenzae mutant. In parallel, Hsf-expressing E. coli selectively acquired vitronectin from serum that resulted in significant inhibition of the MAC. Moreover, when vitronectin was bound to Hsf an increased bacterial adherence and internalization of epithelial cells was observed. Taken together, we have defined a fine-tuned protein-protein interaction between Hsf and vitronectin that may contribute to an increased virulence of Hib.
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| 2. |
- Rydberg Millrud, Camilla, et al.
(författare)
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The Activation Pattern of Blood Leukocytes in Head and Neck Squamous Cell Carcinoma Is Correlated to Survival
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:12
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Tidskriftsartikel (refereegranskat)abstract
- Head and neck squamous cell carcinoma (HNSCC) is known to cause substantial immunosuppression. The present study was designed to characterize blood leukocyte activation in HNSCC and to investigate if the individual activation pattern could be related to tumor progress and survival. The leukocyte activation profile of HNSCC patients and healthy controls was assessed with flow cytometry. HNSCC patients displayed increased numbers of monocytes, neutrophils and total leukocytes as well as an enhanced neutrophil/lymphocyte ratio. In addition, patients had a higher percentage of CD69(+), CD71(+) and CD98(+) T cell subsets and NK cells, and a reduced expression of L-selectin in CD14(high)CD16(+) monocytes and neutrophils, when compared to controls. These changes could be correlated to both tumor burden and spread to lymph nodes. Among the cancer patients an increased neutrophil/lymphocyte ratio, a low neutrophil and CD14(high) CD16(+) monocyte activation state and an elevated CD4/CD8 ratio were related to poor survival. In contrast, a high percentage of CD98(+) Th cells appeared to be associated with a better outcome. Taken together, the present data indicate that HNSCC causes activation of blood leukocytes and that the individual activation pattern can be linked to prognosis.
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| 3. |
- Agarwal, Vaibhav, et al.
(författare)
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Binding of Streptococcus pneumoniae endopeptidase O (PepO) to complement component C1q modulates the complement attack and promotes host cell adherence.
- 2014
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 289:22, s. 15833-15844
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Tidskriftsartikel (refereegranskat)abstract
- The Gram-positive species Streptococcus pneumoniae is a human pathogen causing severe local and life-threatening invasive diseases associated with high mortality rates and death. We demonstrated recently that pneumococcal endopeptidase O (PepO) is an ubiquitously expressed, multifunctional plasminogen and fibronectin binding protein facilitating host cell invasion and evasion of innate immunity. In this study we found that PepO interacts directly with the complement C1q protein, thereby attenuating the classical complement pathway and facilitating pneumococcal complement escape. PepO binds both free C1q and C1 complex in a dose-dependent manner based on ionic interactions. Our results indicate that recombinant PepO specifically inhibits the classical pathway of complement activation in both hemolytic and complement deposition assays. This inhibition is due to direct interaction of PepO with C1q, leading to a strong activation of the classical complement pathway and results in consumption of complement components. In addition, PepO binds the classical complement pathway inhibitor C4BP, thereby regulating downstream complement activation. Importantly, pneumococcal surface-exposed PepO-C1q interaction mediates bacterial adherence to host epithelial cells. Taken together, PepO facilitates C1q-mediated bacterial adherence, while its localized release consumes complement as a result of its activation following binding of C1q, thus representing an additional mechanism of human complement escape by this versatile pathogen.
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| 4. |
- Agarwal, Vaibhav, et al.
(författare)
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Streptococcus pneumoniae endopeptidase O (PepO): a multifunctional plasminogen and fibronectin binding protein, facilitating evasion of innate immunity and invasion of host cells.
- 2013
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 288:10, s. 6849-6863
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae infections remain a major cause of morbidity and mortality worldwide. Therefore a detailed understanding and characterization of the mechanism of host cell colonization and dissemination is critical in order to gain control over this versatile pathogen. Here we identified a novel 72 kDa pneumococcal protein endopeptidase O (PepO), as a plasminogen and fibronectin binding protein. Using a collection of clinical isolates, representing different serotypes, we found PepO to be ubiquitously present both at the gene and at the protein level. In addition, PepO protein was secreted in a growth-phase dependent manner to the culture supernatants of the pneumococcal isolates. Recombinant PepO bound human plasminogen and fibronectin in a dose-dependent manner and plasminogen did not compete with fibronectin for binding PepO. PepO bound plasminogen via lysine residues and the interaction was influenced by ionic strength. Moreover, upon activation of PepO bound plasminogen by urokinase-type plasminogen activator, generated plasmin cleaved complement protein C3b thus assisting in complement control. Furthermore, direct binding assays demonstrated the interaction of PepO with epithelial and endothelial cells that in turn blocked pneumococcal adherence. Moreover, a pepO-mutant strain showed impaired adherence to and invasion of host cells compared to their isogenic wild-type strains. Taken together, the results demonstrated that PepO is ubiquitously expressed plasminogen and fibronectin binding protein, which plays role in pneumococcal invasion of host cells and aids in immune evasion.
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| 5. |
- Blom, Anna, et al.
(författare)
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Streptococcus pneumoniae phosphoglycerate kinase is a novel complement inhibitor affecting the membrane attack complex formation.
- 2014
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 289:47
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Tidskriftsartikel (refereegranskat)abstract
- The Gram-positive bacterium Streptococcus pneumoniae is a major human pathogen that causes infections ranging from acute otitis media to life-threatening invasive disease. Pneumococci have evolved several strategies to circumvent the host immune response, in particular the complement attack. The pneumococcal glycolytic enzyme phosphoglycerate kinase (PGK) is both secreted and bound to the bacterial surface and simultaneously binds plasminogen and its activator tPA. In the present study, we demonstrate that PGK has an additional role in modulating the complement attack. PGK interacted with the membrane attack complex (MAC) components C5, C7 and C9, thereby blocking the assembly and membrane insertion of MAC resulting in significant inhibition of the hemolytic activity of human serum. Recombinant PGK interacted in a dose-dependent manner with these terminal pathway proteins, and the interactions were ionic in nature. In addition, PGK inhibited C9 polymerization both in the fluid phase and on the surface of sheep erythrocytes. Interestingly, PGK bound several MAC proteins simultaneously. While C5 and C7 had partially overlapping binding sites on PGK, C9 did not compete with either one for PGK binding. Moreover, PGK significantly inhibited MAC deposition via both the classical and alternative pathway at the pneumococcal surface. Additionally, upon activation plasmin(ogen) bound to PGK cleaved the central complement protein C3b thereby further modifying the complement attack. In conclusion, our data demonstrate for the first time, to our knowledge, a novel pneumococcal inhibitor of the terminal complement cascade aiding complement evasion by this important pathogen.
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| 6. |
- Malm, Sven, et al.
(författare)
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Acquisition of Complement Inhibitor Serine Protease Factor I and Its Cofactors C4b-Binding Protein and Factor H by Prevotella intermedia.
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Infection with the Gram-negative pathogen Prevotella intermedia gives rise to periodontitis and a growing number of studies implies an association of P. intermedia with rheumatoid arthritis. The serine protease Factor I (FI) is the central inhibitor of complement degrading complement components C3b and C4b in the presence of cofactors such as C4b-binding protein (C4BP) and Factor H (FH). Yet, the significance of complement inhibitor acquisition in P. intermedia infection and FI binding by Gram-negative pathogens has not been addressed. Here we show that P. intermedia isolates bound purified FI as well as FI directly from heat-inactivated human serum. FI bound to bacteria retained its serine protease activity as shown in degradation experiments with (125)I-labeled C4b. Since FI requires cofactors for its activity we also investigated the binding of purified cofactors C4BP and FH and found acquisition of both proteins, which retained their activity in FI mediated degradation of C3b and C4b. We propose that FI binding by P. intermedia represents a new mechanism contributing to complement evasion by a Gram-negative bacterial pathogen associated with chronic diseases.
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| 7. |
- Karlsson, Johanna, 1973, et al.
(författare)
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Comparative Study of Immune Status to Infectious Agents in Elderly Patients with Multiple Myeloma, Waldenstrom's Macroglobulinemia, and Monoclonal Gammopathy of Undetermined Significance.
- 2011
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Ingår i: Clinical and vaccine immunology : CVI. - 1556-6811. ; 18:6, s. 969-77
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Tidskriftsartikel (refereegranskat)abstract
- Whereas patients with multiple myeloma (MM) have a well-documented susceptibility to infections, this has been less studied in other B-cell disorders, such as Waldenstrom's macroglobulinemia (WM) and monoclonal gammopathy of undetermined significance (MGUS). We investigated the humoral immunity to 24 different pathogens in elderly patients with MM (n = 25), WM (n = 16), and MGUS (n = 18) and in age-matched controls (n = 20). Antibody titers against pneumococci, staphylococcal alpha-toxin, tetanus and diphtheria toxoids, and varicella, mumps, and rubella viruses were most depressed in MM patients, next to lowest in WM and MGUS patients, and highest in the controls. In contrast, levels of antibodies specific for staphylococcal teichoic acid, Moraxella catarrhalis, candida, aspergillus, and measles virus were similarly decreased in MM and MGUS patients. Comparable titers in all study groups were seen against Haemophilus influenzae type b (Hib), borrelia, toxoplasma, and members of the herpesvirus family. Finally, a uniform lack of antibodies was noted against Streptococcus pyogenes, salmonella, yersinia, brucella, francisella, and herpes simplex virus type 2. To conclude, although MM patients displayed the most depressed humoral immunity, significantly decreased antibody levels were also evident in patients with WM and MGUS, particularly against Staphylococcus aureus, pneumococci, and varicella. Conversely, immunity was retained for Hib and certain herpesviruses in all study groups.
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| 8. |
- Mukherjee, Oindrilla, et al.
(författare)
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A fusion protein derived from Moraxella catarrhalis and Neisseria meningitidis aimed for immune modulation of human B cells
- 2015
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Ingår i: Human Vaccines & Immunotherapeutics. - : Informa UK Limited. - 2164-5515 .- 2164-554X. ; 11:9, s. 2223-2227
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Tidskriftsartikel (refereegranskat)abstract
- Moraxella IgD-binding protein (MID) is a well characterized trimeric autotransporter that specifically targets the IgD of B cells. We fused the membrane anchor of the meningococcal autotransporter NhhA with the IgD-binding region of MID (aa 962-1200) to create a chimeric protein designated as NID. The aim was to use this specific targeting to provide a better vaccine candidate against meningococci, in particular serogroup B by enhancing the immunogenicity of NhhA. NID was thereafter recombinantly expressed in E. coli. The NID-expressing E. coli bound to peripheral B lymphocytes that resulted in cellular activation. Furthermore, we also successfully expressed NID on outer membrane vesicles, nanoparticles that are commonly used in meningococcal vaccines. This study thus highlights the applicability of the menigococcal-Moraxella fusion protein NID to be used for specific targeting of vaccine components to the IgD B cell receptor.
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| 9. |
- Hadzic, Radinka, et al.
(författare)
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alpha1-Antitrypsin inhibits Moraxella catarrhalis MID protein-induced tonsillar B cell proliferation and IL-6 release.
- 2006
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Ingår i: Immunology Letters. - : Elsevier BV. - 0165-2478 .- 1879-0542. ; 102:2, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- alpha 1-Antitrypsin (AAT) is a major circulating and tissues inhibitor of serine proteinases implicated in the regulation of inflammation and host defence. There is now increasing evidence that AAT may also exhibit anti-inflammatory activities independent of its protease inhibitor function. This study was undertaken to investigate the effects of native (inhibitory) and polymerized (non-inhibitory) forms of AAT on MID (Moraxella IgD binding protein)-induced human tonsillar B cell activation in vitro. We found that 0.5 mu g/ml MID induces B cell proliferation and stimulates IL-6 release (p < 0.001) relative to non-stimulated controls. Both native and polymerized AAT (0.5 mg/ml) inhibited MID-stimulated B cell proliferation in a similar manner (by 70%, p < 0.001), whereas MID-induced IL-6 release was more strongly suppressed by polymefized (9.9-fold, p < 0.001) as compared to native AAT (2.8-fold, p < 0.01). Electrophoretic analysis of cell culture media did not indicate any interaction between AAT and MID, and flow cytometry data showed no competition for the same receptor. The effects of AATs were observed whether added together with MID or 2 h after MID-addition to cell cultures. Thus, our data demonstrate that AAT inhibits MID-induced B cell activation in vitro that is unrelated to its protease inhibitory activity and is not dependent on MID binding to the cell surface.
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| 10. |
- Aung, Kyaw Min, et al.
(författare)
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Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U
- 2016
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Ingår i: Journal of Innate Immunity. - : S. Karger AG. - 1662-811X .- 1662-8128. ; 8:3, s. 269-283
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Tidskriftsartikel (refereegranskat)abstract
- Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia.
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