The role of the elastic fiber protein fibrillin-1 in the pathogenesis of pulmonary emphysema

Contains fulltext : 87184.pdf (publisher's version ) (Open Access)Radboud Universiteit Nijmegen, 16 juni 2011Promotores : Brock, R.E., Dekhuijzen, P.N.R. Co-promotores : Kuppevelt, A.H.M.S.M. van, Krieken, J.H.J.M. van, Hendriks, T., Pals, G.172 p

Fibrillin-1 staining anomalies are associated with increased staining for TGF-beta and elastic fibre degradation; new clues to the pathogenesis of emphysema.

We recently demonstrated aberrant staining of fibrillin-1 in lung tissue specimens with emphysematous lesions. In this study, we have extended this observation by an elaborate analysis of the elastic fibre. Using domain-specific antibodies to fibrillin-1, and to other elastin fibre-associated molecules, lung tissue derived from patients without obvious clinical emphysema, but harbouring various degrees of microscopical emphysematous lesions, was analysed. In addition, the fibrillin-regulated growth factor TGF-beta was studied. Electron microscopy and biochemical analysis of desmosine (a marker for elastin) were also performed. Results were compared with lung tissue derived from patients with clinical emphysema. Domain-specific antibodies recognizing the C-terminal, N-terminal, and middle part of fibrillin-1 showed aberrant staining patterns associated with increasing degrees of microscopical emphysema. Staining for elastin, emilin-1, and fibulin-2 was, however, not aberrant. TGF-beta staining was markedly increased. On the electron microscopic, but not light microscopical, level, initial elastic fibre degradation was noticed in specimens with microscopical emphysema. Lung specimens from patients with clinical emphysema also displayed fragmented fibrillin-1 staining and, in addition, displayed extensive degradation of the elastic fibre. The results suggest that fibrillin-1 anomalies and TGF-beta overexpression are associated with initial events occurring during the emphysematous process. Based on these and other data, a mechanism for emphysematogenesis is proposed

Absence of HDL cholesteryl ester uptake in mice via SR-BI impairs an adequate adrenal glucocorticoid-mediated stress response to fasting.

Contains fulltext : 69489.pdf (Publisher’s version ) (Open Access)Receptor-mediated cholesterol uptake has been suggested to play a role in maintaining the adrenal intracellular free cholesterol pool and the ability to produce hormones. Therefore, in the current study, we evaluated the importance of scavenger receptor class B type I (SR-BI)-mediated cholesteryl ester uptake from HDL for adrenal glucocorticoid hormone synthesis in vivo. No difference was observed in the plasma level of corticosterone between SR-BI-deficient and wild-type mice under ad libitum feeding conditions. Overnight fasting ( approximately 16 h) stimulated the plasma level of corticosterone by 2-fold in wild-type mice. In contrast, no effect of fasting on plasma corticosterone levels was observed in SR-BI-deficient mice, leading to a 44% lower plasma corticosterone level compared with their wild-type littermate controls. In parallel, an almost complete depletion of lipid stores in the adrenal cortex of fasted SR-BI-deficient mice was observed. Plasma adrenocorticotropic hormone levels were increased by 5-fold in fasted SR-BI-deficient mice. SR-BI deficiency induced marked changes in the hepatic expression of the glucocorticoid-responsive genes cholesterol 7alpha-hydroxylase, HMG-CoA synthase, apolipoprotein A-IV, corticosteroid binding globulin, interleukin-6, and tumor necrosis factor-alpha, which coincided with a 42% decreased plasma glucose level under fasting conditions. In conclusion, we show that the absence of adrenal HDL cholesteryl ester uptake in SR-BI-deficient mice impairs the adrenal glucocorticoid-mediated stress response to fasting as a result of adrenal glucocorticoid insufficiency and attenuated liver glucocorticoid receptor signaling, leading to hypoglycemia under fasting conditions

Aberrant fibrillin-1 expression in early emphysematous human lung: a proposed predisposition for emphysema.

Parenchymal destruction, airspace enlargement, and loss of elasticity are hallmarks of pulmonary emphysema. Although the basic mechanism is unknown, there is a consensus that malfunctioning of the extracellular matrix is a major contributor to the pathogenesis of emphysema. In this study, we analyzed the expression of the elastic fiber protein fibrillin-1 in a large number (n=69) of human lung specimens with early-onset emphysema. Specimens were morphologically characterized by the Destructive Index, the Mean Linear Intercept, and the Panel Grading. We observed a strong correlation (P<0.001) of aberrant fibrillin-1 staining with the degree of destruction of lung parenchyma (r=0.71), airspace enlargement (r=0.47), and emphysema-related morphological abnormalities (r=0.69). There were no obvious correlations with age and smoking behavior. Staining for three other extracellular matrix components (type I collagen, type IV collagen, and laminin) was not affected. The aberrant fibrillin-1 staining observed in this study is similar to that observed in Marfan syndrome, a syndrome caused by mutations in the gene encoding fibrillin-1. Strikingly, emphysema is noticed in a number of Marfan patients. This, together with the notion that disruption of the fibrillin-1 gene in mice results in emphysematous lesions, makes fibrillin-1 a strong candidate to be involved in the etiology and pathogenesis of emphysema

Increased expression of interleukin-22 by synovial Th17 cells during late stages of murine experimental arthritis is controlled by interleukin-1 and enhances bone degradation

Item does not contain fulltextOBJECTIVE: Interleukin-22 (IL-22) is a mediator in antimicrobial responses and inflammatory autoimmune diseases. Although IL-22 and its receptor, IL-22R, have been identified in the synovium of rheumatoid arthritis patients, the source of IL-22 and its contribution to disease pathogenicity remain to be established. This study was undertaken to investigate the regulation of IL-22 by Th17 cells in vitro and to evaluate the potential for IL-22 depletion in an experimental arthritis model using mice deficient in the IL-1 receptor antagonist (IL-1Ra-/-). METHODS: Naive murine T cells were cultured under conditions leading to polarization of the cells into subsets of Th1, Th2, induced Treg, and Th17. Cytokines were measured in the culture supernatants, and the cells were analyzed by fluorescence-activated cell sorting. Tissue samples from the inflamed ankle synovium of IL-1Ra-/- mice were isolated, and messenger RNA levels of marker genes were quantified. IL-1Ra-/- mice were treated with neutralizing anti-IL-22 antibodies. Synovial cells were isolated from the inflamed tissue and sorted into fractions for analysis of cytokine production. RESULTS: In vitro tests showed that Th17 cells produced high levels of IL-22 after stimulation with IL-1 or IL-23. Interestingly, a synergistic increase in the production of IL-22 was observed after combining IL-1 and IL-23. In vivo, IL-1Ra-/- mice displayed a progressive erosive arthritis, characterized by up-regulation of IL-17 in mildly and severely inflamed tissue, whereas the levels of IL-22 and IL-22R were increased only in severely inflamed synovia. Anti-IL-22 treatment of IL-1Ra-/- mice significantly reduced the inflammation and bone erosion. Analysis of isolated single cells from the inflamed synovia revealed that IL-22 was mainly produced by IL-17-expressing T cells. CONCLUSION: These findings suggest that IL-22 plays an important role in IL-1-driven chronic joint destruction

Tumour necrosis factor alpha-driven IL-32 expression in rheumatoid arthritis synovial tissue amplifies an inflammatory cascade

Contains fulltext : 97478.pdf (publisher's version ) (Closed access)OBJECTIVE: To investigate the interplay between IL-32 and tumour necrosis factor alpha (TNFalpha) during the chronic inflammation of rheumatoid arthritis (RA) and to assess whether anti-TNFalpha treatment of RA patients modulates synovial IL-32 expression. METHODS: Induction of IL-32gamma by Pam3Cys, lipopolysaccharide, IL-1beta or TNFalpha was investigated in human fibroblast-like synoviocytes (FLS). Stimulation of TNFalpha production by IL-32gamma was studied by adenoviral overexpression of IL-32gamma (AdIL-32gamma) and lipopolysaccharide stimulation of THP1 cells. Silencing of endogenous IL-32 was employed to study cytokine regulation in FLS. AdIL-32gamma followed by TNFalpha stimulation was performed in FLS to investigate cytokine induction. Immunohistochemistry was applied to study IL-32 expression in synovial biopsies from RA patients. RESULTS: TNFalpha potently induced IL-32gamma expression in FLS. Increased TNFalpha, IL-1beta, IL-6 and CXCL8 production was observed after IL-32gamma overexpression and lipopolysaccharide stimulation of THP1 cells. TNFalpha stimulation of FLS after silencing IL-32gamma resulted in diminished IL-6 and CXCL8 production, whereas IL-32gamma overexpression resulted in enhanced IL-6 and CXCL8 levels. Remarkably, the mechanism through which IL-32gamma overexpression induced TNFalpha, IL-1beta and CXCL8 was by counteracting messenger RNA decay. Importantly, treatment of RA patients with anti-TNFalpha resulted in significant reduction of IL-32 protein in synovial tissue. CONCLUSIONS: TNFalpha is a potent inducer of endogenous IL-32 expression and IL-32 itself contributes to prolonged TNFalpha production, thus inducing an important auto-inflammatory loop. Treatment of RA patients with anti-TNFalpha antibodies diminished IL-32 expression in synovial tissue. The potent anti-inflammatory effect of TNFalpha blockade in RA patients may be partly due to the reduction of synovial IL-32 expression

IL-32gamma and Streptococcus pyogenes cell wall fragments synergise for IL-1-dependent destructive arthritis via upregulation of TLR-2 and NOD2.

Item does not contain fulltextOBJECTIVE: To investigate the potential synergism between interleukin (IL) 32gamma and Streptococcus pyogenes cell wall (SCW) fragments in the development of destructive arthritis. METHODS: An adenoviral vector encoding human IL-32gamma (AdIL-32gamma) was constructed and validated in HeLa cells. Fibroblast-like synoviocytes (FLS) were transduced with AdIL-32gamma and stimulated with Toll-like receptor 2 (TLR-2) and nucleotide oligomerisation domain (NOD) 2 ligands. Expression levels of several proinflammatory cytokines, chemokines, matrix degrading enzymes, TLR-2 and NOD2 were measured by quantitative real-time PCR. Furthermore, IL-6 and CXCL8 protein levels were determined. In-vivo synergy between IL-32gamma and SCW was studied by intra-articular injection of AdIL-32gamma in C57Bl/6 mice followed by SCW injection. The contribution of endogenous IL-1 was assessed in mice deficient for both IL-1alpha and IL-1beta. Results : IL-32gamma synergise with TLR-2/NOD2 ligands to induce proinflammatory cytokines, chemokines and matrix degrading enzymes in AdIL-32gamma-transduced FLS. In mice, AdIL-32gamma transduction followed by the injection of SCW displayed aggravated joint inflammation and cartilage destruction. However, IL-1-deficient mice were protected against IL-32gamma/SCW-induced joint changes, indicating a requirement for IL-1 in downstream events triggered by IL-32gamma plus SCW. To elucidate the synergistic mechanism, the authors investigated the expression of two pattern recognition receptors involved in sensing SCW fragments. TLR-2 and NOD2 receptor expression was enhanced by IL-32gamma and Pam3Cys/muramyl dipeptide stimulation in FLS. CONCLUSIONS: Here the authors show that IL-32gamma aggravates SCW-induced arthritis by the upregulation of TLR-2/NOD2 expression and promotes severe joint erosion in an IL-1-dependent fashion. Targeting of IL-32gamma may provide a novel therapy to prevent destructive arthritis.1 oktober 201

The anti-CD20 antibody rituximab reduces the Th17 cell response

Contains fulltext : 98411.pdf (publisher's version ) (Closed access)OBJECTIVE: Rituximab has been shown to be successful in the treatment of rheumatoid arthritis (RA), and this unexpected finding indicates that B cells have an important role in this disease. The present study was undertaken to investigate the mechanism of action of rituximab in RA. METHODS: Twelve patients with active RA were treated with rituximab. Disease activity was evaluated using the 28-joint Disease Activity Score. Synovial biopsy samples obtained at baseline and 12 weeks after treatment initiation were analyzed by microarray, quantitative polymerase chain reaction, and immunohistochemistry. Peripheral blood mononuclear cells (PBMCs) from healthy volunteers and from 4 patients with X-linked agammaglobulinemia were stimulated with the Th17-inducing stimulus Candida albicans, and the response in the presence and absence of rituximab was examined. RESULTS: In RA patients, rituximab reduced expression of retinoic acid-related orphan receptor gammat and interleukin-22 (IL-22) and numbers of Th17-positive cells in synovial tissue, and this correlated with better clinical outcome. Rituximab did not affect tumor necrosis factor alpha (TNFalpha), Th1 cell, or Treg cell responses. Rituximab strongly reduced in vitro IL-17 and IL-22 production induced by C albicans. This effect was not observed in PBMCs from patients with X-linked agammaglobulinemia. CONCLUSION: Rituximab reduced the local Th17 response in RA patients, whereas it did not influence Th1 cell, Treg cell, or TNFalpha responses. The decreased Th17 response was associated with reduced inflammation and better clinical outcome. Moreover, inhibition of the Th17 response by rituximab was lost in the absence of B cells, providing evidence that the effects of rituximab are due to B cell depletion. These data demonstrate an unexpected role of B cells in the development of Th17 responses, which could possibly lead to B cell-based strategies for the treatment of Th17-related autoimmune diseases

Higher airborne pollen concentrations correlated with increased SARS-CoV-2 infection rates, as evidenced from 31 countries across the globe

Pollen exposure weakens the immunity against certain seasonal respiratory viruses by diminishing the antiviral interferon response. Here we investigate whether the same applies to the pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is sensitive to antiviral interferons, if infection waves coincide with high airborne pollen concentrations. Our original hypothesis was that more airborne pollen would lead to increases in infection rates. To examine this, we performed a cross-sectional and longitudinal data analysis on SARS-CoV-2 infection, airborne pollen, and meteorological factors. Our dataset is the most comprehensive, largest possible worldwide from 130 stations, across 31 countries and five continents. To explicitly investigate the effects of social contact, we additionally considered population density of each study area, as well as lockdown effects, in all possible combinations: without any lockdown, with mixed lockdown−no lockdown regime, and under complete lockdown. We found that airborne pollen, sometimes in synergy with humidity and temperature, explained, on average, 44% of the infection rate variability. Infection rates increased after higher pollen concentrations most frequently during the four previous days. Without lockdown, an increase of pollen abundance by 100 pollen/m3 resulted in a 4% average increase of infection rates. Lockdown halved infection rates under similar pollen concentrations. As there can be no preventive measures against airborne pollen exposure, we suggest wide dissemination of pollen−virus coexposure dire effect information to encourage high-risk individuals to wear particle filter masks during high springtime pollen concentrations