Role In Pathogenesis Of Sarcoidosis Research Articles

Altered microRNA expression in patients with sarcoidosis.

Background Sarcoidosis is a granulomatous multisystem disease of uncertain aetiology. The disease has major inflammatory and immune components; however, the immunopathogenesis is not well understood. Micro ribonucleic acids (microRNAs) are classes of miniature, single-stranded, non-coding RNAs. Their key recognised role includes mediating the silencing of target genes post-transcriptionally. Recently, the role of miRNAs has gained interest in numerous disorders, suggested as being involved in pathogenesis of those diseases and acting as disease markers. Very little is known about the role of miRNAs in sarcoidosis, with nothing known regarding miRNAs in South African patients. The main objective, therefore, was to investigate the serum expression of approximately 800 miRNAs in patients with sarcoidosis compared with race-, age- and gender-matched healthy controls. Methods A total of six patients and six matched controls participated in this study. Whole blood samples were collected in EDTA tubes, processed and the plasma retained. RNA was extracted from the stored plasma samples using the QIAGEN miRNeasy Mini Kit® and concentrated using a salt-ethanol precipitation. The extracted miRNA was profiled using an nCounter® miRNA human v3 expression assay and data analysed using the nSolver™ Analysis Software. Results After excluding one sample/control pair because of cellular RNA contamination, the remaining five patient and five matched control samples were analysed, and 145 miRNAs were found to be potentially differentially expressed. On applying a Bonferroni correction, the only miRNA that was significantly different was miRNA let-7a-5p, which was significantly overexpressed (141-fold change; p<0.0003) in patients compared with controls. Conclusion This is the first miRNA report of differentially expressed miRNAs in the serum of patients with sarcoidosis and matched healthy controls in South Africa. The results obtained suggest that miRNAs may play a role in sarcoidosis pathogenesis. Whether these molecules have diagnostic or prognostic implications, needs future studies recruiting larger patient cohorts.

Hypoxia Promotes a Mixed Inflammatory-Fibrotic Macrophages Phenotype in Active Sarcoidosis.

BackgroundMacrophages are pivotal cells in sarcoidosis. Monocytes-derived (MD) macrophages have recently been demonstrated to play a major role especially in pulmonary sarcoidosis. From inflammatory tissues to granulomas, they may be exposed to low oxygen tension environments. As hypoxia impact on sarcoidosis immune cells has never been addressed, we designed the present study to investigate MD-macrophages from sarcoidosis patients in this context. We hypothesized that hypoxia may induce functional changes on MD-macrophages which could have a potential impact on the course of sarcoidosis.MethodsWe studied MD-macrophages, from high active sarcoidosis (AS) (n=26), low active or inactive sarcoidosis (IS) (n=24) and healthy controls (n=34) exposed 24 hours to normoxia (21% O2) or hypoxia (1.5% O2). Different macrophage functions were explored: hypoxia-inducible factor-1α (HIF-1α) and nuclear factor-kappa B (NF-κB) activation, cytokines secretion, phagocytosis, CD80/CD86/HLA-DR expression, profibrotic response.ResultsWe observed that hypoxia, with a significantly more pronounced effect in AS compared with controls and IS, increased the HIF-1α trans-activity, promoted a proinflammatory response (TNFα, IL1ß) without activating NF-κB pathway and a profibrotic response (TGFß1, PDGF-BB) with PAI-1 secretion associated with human lung fibroblast migration inhibition. These results were confirmed by immunodetection of HIF-1α and PAI-1 in granulomas observed in pulmonary biopsies from patients with sarcoidosis. Hypoxia also decreased the expression of CD80/CD86 and HLA-DR on MD-macrophages in the three groups while it did not impair phagocytosis and the expression of CD36 expression on cells in AS and IS at variance with controls.ConclusionsHypoxia had a significant impact on MD-macrophages from sarcoidosis patients, with the strongest effect seen in patients with high active disease. Therefore, hypoxia could play a significant role in sarcoidosis pathogenesis by increasing the macrophage proinflammatory response, maintaining phagocytosis and reducing antigen presentation, leading to a deficient T cell response. In addition, hypoxia could favor fibrosis by promoting profibrotic cytokines response and by sequestering fibroblasts in the vicinity of granulomas.

Infliximab therapy balances regulatory T cells, tumour necrosis factor receptor 2 (TNFR2) expression and soluble TNFR2 in sarcoidosis

Sarcoidosis is a systemic granulomatous disease of unknown aetiology that most commonly affects the lungs. Although elevated levels of regulatory T cells (Tregs ) have been reported, the extent to which they play a role in sarcoidosis pathogenesis remains unclear. Tumour necrosis factor (TNF) is thought to be one of the driving forces behind granuloma formation, illustrated by the efficacy of infliximab in severe sarcoidosis. Tregs express TNF receptor 2 (TNFR2) highly. Here, we examined the influence of infliximab therapy on Tregs and (soluble) TNFR2 levels in sarcoidosis, and correlated these with response to therapy. We observed that relative frequencies of Tregs were significantly higher in patients (n = 54) compared to healthy controls (n = 26; median 6·73 versus 4·36%; P < 0·001) and decreased following therapy (4·95; P < 0·001). Baseline TNFR2 expression on Tregs was increased significantly in patients versus controls (99·4 versus 96·2%; P = 0·031), and also in responders to therapy versus non-responders (99·6 versus 97·3%; P = 0·012). Furthermore, baseline soluble TNFR2 (sTNFR2) was higher in responders than in non-responders (mean 174 versus 107 pg/ml; P = 0·015). After treatment, responders showed a significant reduction in sTNFR2 levels in peripheral blood (-44·7 pg/ml; P < 0·001), in contrast to non-responders (+3·59 pg/ml). Our results demonstrated that Treg frequencies and TNFR2 expression on Tregs are increased in sarcoidosis, followed by a decline during infliximab therapy, suggesting a pathophysiological role of this T cell subset. Interestingly, sTNFR2 levels at baseline differed significantly between responders and non-responders, making it a potential marker in predicting which patients might benefit from infliximab.

Annexins family: insights into their functions and potential role in pathogenesis of sarcoidosis.

Annexins are Ca2+-regulated phospholipid-binding proteins that play an important role in the cell life cycle, exocytosis, and apoptosis. Annexin A11 is one of the oldest vertebrate annexins that has a crucial role in sarcoidosis pathogenesis. The mechanism of effect in sarcoidosis granuloma cells may be due to alterations in apoptosis. Immune cells with a specific mutation at protein location 230 are resistant to apoptosis and consequently have continued effects on inflammation and progression of sarcoidosis. The mechanism of action of annexin A11 may be based upon alterations in delivering calcium to two different apoptosis pathways (caspase and P53).

Spontaneous and lipopolysacharide induced production of tumor necrosis factor-α in interstitial lung diseases

Background and objectives: Tumor necrosis factor-α (TNF-α) was found to play role in pathogenesis of sarcoidosis, idiopathic pulmonary fibrosis (IPF) and hypersensitivity pneumonitis (HP). TNF-α is produced primarily by activated macrophages, but T-cells also may be a source of this cytokine. Lipopolysacharide (LPS) induced TNF-α production was found to differ among interstitial lung diseases and healthy control. The aim of our study was to find out, if sources of TNF-α differ in sarcoidosis, IPF and HP patients. Moreover, differences between LPS induced production of TNF-α were studied.

Multiple mycobacterial antigens are targets of the adaptive immune response in pulmonary sarcoidosis

IntroductionSarcoidosis is a multisystem granulomatous disease for which the association with mycobacteria continues to strengthen. It is hypothesized that a single, poorly degradable antigen is responsible for sarcoidosis pathogenesis. Several reports from independent groups support mycobacterial antigens having a role in sarcoidosis pathogenesis. To identify other microbial targets of the adaptive immune response, we tested the ability of CD4+ and CD8+ T cells to recognize multiple mycobacterial antigens.MethodsFifty-four subjects were enrolled in this study: 31 sarcoidosis patients, nine non-tuberculosis mycobacterial (NTM) infection controls, and 14 PPD- controls. Using flow cytometry, we assessed for Th1 immune responses to ESAT-6, katG, Ag85A, sodA, and HSP.ResultsAlveolar T-cells from twenty-two of the 31 sarcoidosis patients produced a CD4+ response to at least one of ESAT-6, katG, Ag85A, sodA, or HSP, compared to two of 14 PPD- controls (p = 0.0008) and five of nine NTM controls (p = 0.44), while eighteen of the 31 sarcoidosis subjects tested produced a CD8+ response to at least one of the mycobacterial antigens compared to two of 14 PPD- controls (p = 0.009) and three of nine NTM controls (0.26). Not only did the BAL-derived T cells respond to multiple virulence factors, but also to multiple, distinct epitopes within a given protein. The detection of proliferation upon stimulation with the mycobacterial virulence factors demonstrates that these responses are initiated by antigen specific recognition.ConclusionsTogether these results reveal that antigen-specific CD4+ and CD8+ T cells responses to multiple mycobacterial epitopes are present within sites of active sarcoidosis involvement, and that these antigen-specific responses are present at the time of diagnosis.

Female-specific association of C-C chemokine receptor 5 gene polymorphisms with Löfgren’s syndrome

C-C chemokine receptors have been suggested to play an important role in sarcoidosis pathogenesis. Previous investigation of the C-C chemokine receptor 5 (CCR5) gene revealed the association of the HHC haplotype with "persistent lung involvement" in two European sarcoidosis populations. Based on this finding, we investigated a possible association of the HHC haplotype and its marker alleles in an extended German sarcoidosis sample that comprised 995 German sarcoidosis families including individuals with the chronic and acute form of the disease, further refined to patients with and without Löfgren's syndrome. We genotyped this sample and 538 healthy control subjects for 8 single nucleotide polymorphisms (SNPs) that define the HHC haplotype in the CCR5 genomic region. Analysis of 3 sarcoidosis phenotypes (chronic, acute and Löfgren's syndrome) revealed that the HHC haplotype was not associated with chronic sarcoidosis although a substantial overlap can be assumed between the chronic form examined in our study and "persistent parenchymal lung involvement", the phenotype for which an association was previously established. However, 2 marker alleles in the putative CCR5 promoter, which are part of the HHC haplotype, are associated with Löfgren's syndrome. Strikingly, the association is restricted to females. This finding is consistent with recently described sex-specific manifestations of Löfgren's syndrome and with previous functional studies suggesting an estrogen-dependent CCR5 expression. The female-specific association of SNPs in the putative CCR5 promoter region with Löfgren's syndrome raises the possibility that the dysregulated, sex-specific modification of CCR5 expression could contribute to the increased risk of women to develop the disease.

Multiple Mycobacterium antigens induce interferon-gamma production from sarcoidosis peripheral blood mononuclear cells.

Studies of sarcoidosis immunology have noted oligoclonal T cell populations, suggesting cell-mediated immunity that is antigen-specific. Sarcoidosis immunology and pathology are most similar to mycobacterial infections. Mycobacterium tuberculosis infection in mice and humans reflects T helper 1 (Th1) immune responses to multiple cell wall and secreted antigens. We investigated if the oligoclonal immune response in individual sarcoidosis subjects could be elicited by multiple secreted mycobacterial antigens by performing ex vivo enzyme-linked immunospot assay (ELISPOT) on peripheral blood mononuclear cells (PBMC) from 30 sarcoidosis, 26 purified protein derivative negative (PPD-) control and 10 latent tuberculosis subjects (PPD+) to assess Th1 responses to mycobacterial superoxide dismutase A (sodA), catalase-peroxidase (katG) and early secreted antigenic target protein (ESAT-6). A significant difference was noted among the sarcoidosis and PPD- control subjects to ESAT-6 [12 of 30 versus one of 26 (P = 0.0014)], katG [nine of 30 versus none of 26 (P = 0.002)] and sodA [12 of 30 versus none of 26 (P = 0.002)]. There was no significant difference between sarcoidosis and PPD+ subjects. Twelve sarcoidosis subjects recognized two or more mycobacterial proteins, as well as multiple distinct epitopes within individual proteins. One sarcoidosis subject on whom we collected bronchoalveolar lavage (BAL) fluid and PBMC had no recognition of mycobacterial antigens using PBMC, but BAL fluid demonstrated strong Th1 immune responses to ESAT-6 and katG. Individual sarcoidosis subjects recognized not only multiple mycobacterial proteins, but multiple distinct peptides within a specific protein, thus demonstrating that multiple mycobacterial epitopes elicit the Th1 immune response observed. Immune responses by sarcoidosis T cells to mycobacterial proteins may have an important role in sarcoidosis pathogenesis.

The Clara cell10 adenine38guanine polymorphism and sarcoidosis susceptibility in Dutch and Japanese subjects.

CC10 (CC16, uteroglobin) is a pulmonary protein postulated to play a counter regulatory role in sarcoidosis pathogenesis. The adenine38guanine (A38G) polymorphism of the encoding CC10 gene (SCGB1A1) is functional. Recently, an association between the low CC10 producing 38A allele and sarcoidosis susceptibility has been reported in Japanese patients from Hokkaido. The aim of the present study was to confirm this association in a clinically well characterized population of Dutch white and Kyoto Japanese patients with sarcoidosis and control subjects. No difference in genotype or allele frequency was found between patients with sarcoidosis and control subjects in either ethnic population. Remarkably, however, a significant difference was found between the control subjects from Kyoto and Hokkaido, but not between the Japanese groups of patients with sarcoidosis. Furthermore, review of previously published A38G genotyping results showed a consistent difference in CC10 A38G allele frequencies between whites and Japanese subjects. We conclude that the CC10 A38G polymorphism does not influence sarcoidosis susceptibility in Dutch whites or in Japanese subjects from Kyoto. This stresses the importance of studying the influence of polymorphisms on disease susceptibility in multiple ethnically and geographically distinct disease and control populations before reaching conclusions.

Direct Demonstration of the Productive Capability of Cytokines at the Single Cell Level in Lung Sarcoidosis Using Multicolor Cytometry

Background: Sarcoidosis is a chronic systemic disorder of unknown etiology characterized by noncaseating epithelioid cell granulomatous lesions, around which an increasing number of CD4+ T cells infiltrate. These CD4+ T cells may release interferon-γ (IFN-γ) and interleukin-2 (IL-2). These cytokines are considered to play an important role in pathogenesis of sarcoidosis. Methods: We employed a modification of Jung’s method using multicolor flow cytometry to assess the capability of single cells obtained from bronchoalveolar lavage (BAL) fluid to produce various cytokines. BAL CD4+ T cell production of IFN-γ, IL-2 and IL-4 after phorbol ester and ionomycin stimulation were studied. Results: The percentage of IFN-γ- and IL-2-producing CD4+ T cells was significantly higher in patients with sarcoidosis compared to healthy volunteers [84.7 ± 7.5 vs. 51.2 ± 14.8% (p < 0.005), and 75.3 ± 8.7 vs. 39.8 ±11.0% (p < 0.001), respectively]. No significant difference in the percentage of IL-4-producing CD4+ T cells was noted (1.2 ± 0.6 vs. 3.5 ± 2.6%; not significant), whereas the absolute number of IL-4-producing CD4+ T cells was significantly higher in patients with sarcoidosis compared to healthy volunteers (563.6 ± 330.2 vs. 50.9 ± 66.9/ml; p < 0.005). In the IL-4-producing CD4+ T cells, about 80% of cells concomitantly produced IFN-γ and more than 60% of cells also produced IL-2. Conclusion: We demonstrate that Th1-like-producing cells are predominant in the CD4+ as well as in the CD8+ T cell subset of patients with sarcoidosis. We for the first time demonstrated concomitant capabilities of BAL CD4+ T cells to produce Th1 and Th2 cytokines at the single cell level by multicolor flow cytometry.