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Sarcoidosis is a granulomatous disorder of unknown cause, affecting multiple organs, but mainly the lungs. The exact order of immunological events remains obscure. Reviewing current literature, combined with careful clinical observations, we propose a model for granuloma formation in pulmonary sarcoidosis. A tight collaboration between macrophages, dendritic cells and lymphocyte subsets, initiates the first steps towards granuloma formation, orchestrated by cytokines and chemokines. In a substantial part of pulmonary sarcoidosis patients, granuloma formation becomes an on-going process, leading to debilitating disease and sometimes death. The immunological response, determining granuloma sustainment is not well understood. An impaired immunosuppressive function of regulatory T cells has been suggested to contribute to the exaggerated response. Interestingly, therapeutical agents commonly used in sarcoidosis, such as glucocorticosteroids and anti-TNF agents, interfere with granuloma integrity and restore the immune homeostasis in autoimmune disorders. Increasing insight into their mechanisms of action may contribute to the search for new therapeutical targets in pulmonary sarcoidosis. [ABSTRACT FROM AUTHOR]

Abstract Background Sarcoidosis is a granulomatous disease characterized by a seemingly exaggerated immune response against a difficult to discern antigen. Dendritic cells (DCs) are pivotal antigen presenting cells thought to play an important role in the pathogenesis. Paradoxically, decreased DC immune reactivity was reported in blood samples from pulmonary sarcoidosis patients. However, functional data on lung DCs in sarcoidosis are lacking. We hypothesized that at the site of disease DCs are mature, immunocompetent and involved in granuloma formation. Methods We analyzed myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in broncho-alveolar lavage (BAL) and blood from newly diagnosed, untreated pulmonary sarcoidosis patients and healthy controls using 9-color flowcytometry. DCs, isolated from BAL using flowcytometric sorting (mDCs) or cultured from monocytes (mo-DCs), were functionally assessed in a mixed leukocyte reaction with naïve allogeneic CD4+ T cells. Using Immunohistochemistry, location and activation status of CD11c+DCs was assessed in mucosal airway biopsies. Results mDCs in BAL, but not in blood, from sarcoidosis patients were increased in number when compared with mDCs from healthy controls. mDCs purified from BAL of sarcoidosis patients induced T cell proliferation and differentiation and did not show diminished immune reactivity. Mo-DCs from patients induced increased TNFα release in co-cultures with naïve allogeneic CD4+ T cells. Finally, immunohistochemical analyses revealed increased numbers of mature CD86+ DCs in granuloma-containing airway mucosal biopsies from sarcoidosis patients. Conclusion Taken together, these finding implicate increased local DC activation in granuloma formation or maintenance in pulmonary sarcoidosis.

Autotaxin (ATX) contributes to the production of lysophosphatidic acid (LPA), which is associated with fibrosis development in idiopathic pulmonary fibrosis (IPF). The ATX inhibitor ziritaxestat failed to reduce decline in forced vital capacity (FVC) in patients with IPF in ISABELA 1 and 2 (NCT03711162 and NCT03733444), two identically designed phase III studies. In the current analysis, we evaluated pharmacokinetic and pharmacodynamic data from the pooled ISABELA studies to determine whether the lack of efficacy could be attributed to insufficient exposure and/or target engagement. Nonlinear mixed effect modeling was performed to predict ziritaxestat exposure in individual patients and describe its effect on LPA C18:2 levels. We assessed whether there was a correlation between ziritaxestat and ATX concentration and evaluated the relationship between LPA C18:2 reduction and change from baseline in FVC. Ziritaxestat exposure in patients with IPF was numerically lower in those who received ziritaxestat on top of pirfenidone than in those who received ziritaxestat on top of nintedanib or ziritaxestat alone. In most patients, LPA C18:2 reduction was comparable to that reported in healthy volunteers. ATX concentrations increased over time and correlated weakly with ziritaxestat exposure and LPA C18:2 reduction. No correlation between reduction in LPA C18:2 and change from baseline in FVC was apparent. Based on these evaluations, exposure and target engagement are not thought to have contributed to the lack of efficacy observed. We hypothesize that the lack of efficacy of ziritaxestat in the ISABELA program, despite adequate LPA reduction, could be due to the involvement of an alternative pro-fibrotic pathway., (© 2023 Galapagos NV and The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Importance: There is a major need for effective, well-tolerated treatments for idiopathic pulmonary fibrosis (IPF)., Objective: To assess the efficacy and safety of the autotaxin inhibitor ziritaxestat in patients with IPF., Design, Setting, and Participants: The 2 identically designed, phase 3, randomized clinical trials, ISABELA 1 and ISABELA 2, were conducted in Africa, Asia-Pacific region, Europe, Latin America, the Middle East, and North America (26 countries). A total of 1306 patients with IPF were randomized (525 patients at 106 sites in ISABELA 1 and 781 patients at 121 sites in ISABELA 2). Enrollment began in November 2018 in both trials and follow-up was completed early due to study termination on April 12, 2021, for ISABELA 1 and on March 30, 2021, for ISABELA 2., Interventions: Patients were randomized 1:1:1 to receive 600 mg of oral ziritaxestat, 200 mg of ziritaxestat, or placebo once daily in addition to local standard of care (pirfenidone, nintedanib, or neither) for at least 52 weeks., Main Outcomes and Measures: The primary outcome was the annual rate of decline for forced vital capacity (FVC) at week 52. The key secondary outcomes were disease progression, time to first respiratory-related hospitalization, and change from baseline in St George's Respiratory Questionnaire total score (range, 0 to 100; higher scores indicate poorer health-related quality of life)., Results: At the time of study termination, 525 patients were randomized in ISABELA 1 and 781 patients in ISABELA 2 (mean age: 70.0 [SD, 7.2] years in ISABELA 1 and 69.8 [SD, 7.1] years in ISABELA 2; male: 82.4% and 81.2%, respectively). The trials were terminated early after an independent data and safety monitoring committee concluded that the benefit to risk profile of ziritaxestat no longer supported their continuation. Ziritaxestat did not improve the annual rate of FVC decline vs placebo in either study. In ISABELA 1, the least-squares mean annual rate of FVC decline was -124.6 mL (95% CI, -178.0 to -71.2 mL) with 600 mg of ziritaxestat vs -147.3 mL (95% CI, -199.8 to -94.7 mL) with placebo (between-group difference, 22.7 mL [95% CI, -52.3 to 97.6 mL]), and -173.9 mL (95% CI, -225.7 to -122.2 mL) with 200 mg of ziritaxestat (between-group difference vs placebo, -26.7 mL [95% CI, -100.5 to 47.1 mL]). In ISABELA 2, the least-squares mean annual rate of FVC decline was -173.8 mL (95% CI, -209.2 to -138.4 mL) with 600 mg of ziritaxestat vs -176.6 mL (95% CI, -211.4 to -141.8 mL) with placebo (between-group difference, 2.8 mL [95% CI, -46.9 to 52.4 mL]) and -174.9 mL (95% CI, -209.5 to -140.2 mL) with 200 mg of ziritaxestat (between-group difference vs placebo, 1.7 mL [95% CI, -47.4 to 50.8 mL]). There was no benefit with ziritaxestat vs placebo for the key secondary outcomes. In ISABELA 1, all-cause mortality was 8.0% with 600 mg of ziritaxestat, 4.6% with 200 mg of ziritaxestat, and 6.3% with placebo; in ISABELA 2, it was 9.3% with 600 mg of ziritaxestat, 8.5% with 200 mg of ziritaxestat, and 4.7% with placebo., Conclusions and Relevance: Ziritaxestat did not improve clinical outcomes compared with placebo in patients with IPF receiving standard of care treatment with pirfenidone or nintedanib or in those not receiving standard of care treatment., Trial Registration: ClinicalTrials.gov Identifiers: NCT03711162 and NCT03733444.

Rationale: Idiopathic Pulmonary Fibrosis (IPF) is thought to be triggered by repeated alveolar epithelial cell injury. Current evidence suggests that aberrant immune activation may contribute. However, the role of B-cell activation remains unclear. We determined the phenotype and activation status of B-cell subsets and evaluated the contribution of activated B-cells to the development of lung fibrosis both in humans and in mice., Methods: B-cells in blood, mediastinal lymph node, and lung single-cell suspensions of IPF patients and healthy controls (HC) were characterized using 14-color flow cytometry. Mice were exposed to bleomycin to provoke pulmonary fibrosis., Results: More IgA + memory B-cells and plasmablasts were found in blood (n = 27) and lungs (n = 11) of IPF patients compared to HC (n = 21) and control lungs (n = 9). IPF patients had higher levels of autoreactive IgA in plasma, which correlated with an enhanced decline of forced vital capacity (p = 0.002, r = - 0.50). Bruton's tyrosine kinase expression was higher in circulating IPF B-cells compared to HC, indicating enhanced B-cell activation. Bleomycin-exposed mice had increased pulmonary IgA + germinal center and plasma cell proportions compared to control mice. The degree of lung fibrosis correlated with pulmonary germinal center B-cell proportions (p = 0.010, r = 0.88)., Conclusion: Our study demonstrates that IPF patients have more circulating activated B-cells and autoreactive IgA, which correlate with disease progression. These B-cell alterations were also observed in the widely used mouse model of experimental pulmonary fibrosis. Autoreactive IgA could be useful as a biomarker for disease progression in IPF.

Background: Patients with idiopathic pulmonary fibrosis (IPF) treated with PRM-151, a recombinant human pentraxin 2 protein, in a phase 2 double-blind, randomised controlled trial had significantly reduced decline in percentage of predicted forced vital capacity (FVC) and stabilised 6-min walking distance compared with placebo over a 28-week period. Here we report the 76-week results of an open-label extension study., Methods: Patients who completed the 28-week double-blind period of the PRM-151-202 trial were eligible to participate in the open-label extension study. Patients previously enrolled in the PRM-151 group continued this treatment and those previously in the placebo group crossed over to PRM-151. All patients received PRM-151 in 28-week cycles with loading doses of 10 mg/kg by 60 min intravenous infusions on days 1, 3, and 5 in the first week of each cycle followed by one infusion of 10 mg/kg every 4 weeks. The primary objective of the open-label extension study was to assess the long-term safety and tolerability of PRM-151, which were assessed by analysing adverse events (AEs) up to week 76 in all patients who received at least one dose of PRM-151 during the open-label extension study. Exploratory efficacy analyses were done by assessing changes from baseline in percentage of predicted FVC and 6-min walking distance, with descriptive statistics to week 76 and with random-intercept mixed models to week 52. This study is registered with ClinicalTrials.gov, number NCT02550873, and with EudraCT, number 2014-004782-24., Findings: Of 116 patients who completed the double-blind treatment period, 111 entered the open-label extension study (74 from the PRM-151 group and 37 from the placebo group). 84 (76%) of 111 patients received concomitant IPF therapy (pirfenidone n=55 or nintedanib n=29). AEs were consistent with long-term IPF sequelae. 31 (28%) patients had serious AEs. Those occurring in two or more patients were pneumonia (six [5%] of 111), IPF exacerbation (four [4%]), IPF progression (four [4%]), and chest pain (two [2%]). 21 (19%) patients had severe AEs, of which IPF exacerbation and IPF progression each occurred in two (2%) patients. Two (2%) patients experienced life-threatening AEs (one had pneumonia and one had small-cell lung cancer extensive stage). A persistent treatment effect was observed for PRM-151 in patients who continued treatment, with a decline in percentage of predicted FVC of -3·6% per year and in 6-min walking distance of -10·5 m per year at week 52. In patients who started PRM-151 during the open-label extension study, compared with the slopes for placebo, decline reduced for percentage of predicted FVC (from -8·7% per year in weeks 0-28 to -0·9% per year in weeks 28-52, p<0·0001) and 6-min walking distance (from -54·9 m per year to -3·5 m per year, p=0·0224)., Interpretation: Long-term treatment with PRM-151 was well tolerated and the effects on percentage of predicted FVC and 6-min walking distance were persistent on continuation and positive in patients who crossed over from placebo. These findings support further study of PRM-151 in larger populations of patients with IPF., Funding: Promedior., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Importance: Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with poor prognosis. Approved therapies do not halt disease progression., Objective: To determine the effect of recombinant human pentraxin 2 vs placebo on change from baseline to week 28 in mean forced vital capacity (FVC) percentage of predicted value., Design, Setting, and Participants: Phase 2, randomized, double-blind, placebo-controlled trial conducted at 18 sites in 7 countries of eligible patients with IPF (N = 117; aged 40-80 years; FVC ≥50% and ≤90% predicted; ratio of forced expiratory volume in the first second/FVC >0.70; diffusing capacity for carbon monoxide [Dlco] ≥25% and ≤90% predicted; and distance of ≥150 m on the 6-minute walk test). Study period was August 2015-May 2017., Interventions: Patients were randomized to receive either recombinant human pentraxin 2 (10 mg/kg intravenous every 4 weeks, n = 77) or placebo (n = 39) for 24 weeks, and stratified by concurrent IPF treatment status., Main Outcomes and Measures: The primary end point was the least-squares mean change in FVC percentage of predicted value from baseline to week 28 (minimal clinically important difference, decline of 2%-6%). Secondary end points included mean change in lung volumes (total, normal, and interstitial lung abnormalities) on high-resolution computed tomography (HRCT) and 6-minute walk distance (minimal clinically important difference, 24-45 m)., Results: Of 117 randomized patients, 116 received at least 1 dose of study drug (mean age, 68.6 years; 81.0% men; mean time since IPF diagnosis, 3.8 years), and 111 (95.7%) completed the study. The least-squares mean change in FVC percentage of predicted value from baseline to week 28 in patients treated with recombinant human pentraxin 2 was -2.5 vs -4.8 for those in the placebo group (difference, +2.3 [90% CI, 1.1 to 3.5]; P = .001). No significant treatment differences were observed in total lung volume (difference, 93.5 mL [90% CI, -27.7 to 214.7]), quantitative parenchymal features on HRCT (normal lung volume difference, -1.2% [90% CI, -4.4 to 1.9]; interstitial lung abnormalities difference, 1.1% [90% CI, -2.2 to 4.3]), or measurement of Dlco (difference, -0.4 [90% CI, -2.6 to 1.7]). The change in 6-minute walk distance was -0.5 m for patients treated with recombinant human pentraxin 2 vs -31.8 m for those in the placebo group (difference, +31.3 m [90% CI, 17.4 to 45.1]; P < .001). The most common adverse events in the recombinant human pentraxin 2 vs placebo group were cough (18% vs 5%), fatigue (17% vs 10%), and nasopharyngitis (16% vs 23%)., Conclusions and Relevance: In this preliminary study, recombinant human pentraxin 2 vs placebo resulted in a slower decline in lung function over 28 weeks for patients with idiopathic pulmonary fibrosis. Further research should more fully assess efficacy and safety., Trial Registration: clinicaltrials.gov Identifier: NCT02550873.

Background: Prednisone is used as first-line therapy for pulmonary sarcoidosis. What dosing strategy has the best balance between effect and side-effects is largely unknown. We analyzed change in forced vital capacity (FVC) and weight during different prednisone doses used in daily practice for treatment naïve pulmonary sarcoidosis patients., Methods: Multilevel models were used to describe FVC and weight change over time. Correlations were calculated using linear regression models., Results: Fifty-four patients were included. FVC changed over time (p < 0.001), with an average increase of 9.6% predicted (95% CI: 7.2 to 12.1) at 12 months. Weight changed significantly over time (p < 0.001), with an average increase of 4.3 kg (95% CI: 3.0 to 5.6) at 12 months. Although FVC and weight changed significantly over time, there was little correlation between prednisone dose and FVC change, while weight increase correlated significantly with cumulative prednisone dose at 24 months. In patients treated with a high cumulative prednisone dose, baseline FVC was on average lower (p = 0.001) compared to low dose treated patients, while no significant differences were observed in need for second/third-line therapy or number of exacerbations. A strategy leading to a low cumulative dose at 12 months was defined by rapid dose tapering to 10 mg/day within 3.5 months., Conclusions: These results suggest that prednisone therapy aimed at improving or preserving FVC in newly- treated pulmonary sarcoidosis can often be reduced in dose, using a treatment regimen that is characterized by early dose tapering., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The lung-draining mediastinal lymph nodes (MLNs) are currently widely used to diagnose sarcoidosis. We previously reported that T-helper (Th) 17.1 cells are responsible for the exaggerated interferon-γ production in sarcoidosis lungs. In this study, we aimed to investigate 1) whether Th17.1 cells are also increased in the MLNs of sarcoidosis patients and 2) whether frequencies of the Th17.1 cells at diagnosis may correlate with disease progression.MLN cells from treatment-naive pulmonary sarcoidosis patients (n=17) and healthy controls (n=22) and peripheral blood mononuclear cells (n=34) and bronchoalveolar lavage fluid (BALF) (n=36) from sarcoidosis patients were examined for CD4 + T-cell subset proportions using flow cytometry.Higher proportions of Th17.1 cells were detected in sarcoidosis MLNs than in control MLNs. Higher Th17.1 cell proportions were found in sarcoidosis BALF compared with MLNs and peripheral blood. Furthermore, BALF Th17.1 cell proportions were significantly higher in patients developing chronic disease than in patients undergoing resolution within 2 years of clinical follow-up.These data suggest that Th17.1 cell proportions in pulmonary sarcoidosis can be evaluated as a diagnostic and/or prognostic marker in clinical practice and could serve as a new therapeutic target., Competing Interests: Conflict of interest: C.E. Broos, R.W. Hendriks, M. Kool have a patent P117584NL00 (Th17.1 cells as biomarker for sarcoidosis disease prognosis) pending to C.E. Broos, R.W. Hendriks, M. Kool and J.R. Miedema., (Copyright ©ERS 2018.)

Pulmonary fibrosis greatly impacts patients and their partners. Unmet needs of patients are increasingly acknowledged; the needs of partners often remain unnoticed. Little is known about the best way to educate patients and partners. We investigated pulmonary fibrosis patients' and partners' perspectives and preferences in care, and the differences in these between the Netherlands and Germany. Additionally, we evaluated whether interactive interviewing could be a novel education method in this population. Patients and partners were interviewed during pulmonary fibrosis patient information meetings. In the Netherlands, voting boxes were used and results were projected directly. In Germany, questionnaires were used. In the Netherlands, 278 patients and partners participated; in Germany, 51. Many participants experienced anxiety. Almost all experienced misunderstanding, because people do not know what pulmonary fibrosis is. All expressed a need for information, psychological support and care for partners. Use of the interactive voting system was found to be pleasant (70%) and informative (94%). This study improves the knowledge of care needs of patients with pulmonary fibrosis and their partners. There were no major differences between the Netherlands and Germany. Interactive interviewing could be an attractive method to acquire insights into the needs and preferences of patients and partners, while providing them with information at the same time., Competing Interests: Conflict of interest: Disclosures can be found alongside this article at openres.ersjournals.com

Rationale: Pulmonary sarcoidosis is classically defined by T-helper (Th) cell type 1 inflammation (e.g., IFN-γ production by CD4(+) effector T cells). Recently, IL-17A-secreting cells have been found in lung lavage, invoking Th17 immunity in sarcoidosis. Studies also identified IL-17A-secreting cells that expressed IFN-γ, but their abundance as a percentage of total CD4(+) cells was either low or undetermined., Objectives: Based on evidence that Th17 cells can be polarized to Th17.1 cells to produce only IFN-γ, our goal was to determine whether Th17.1 cells are a prominent source of IFN-γ in sarcoidosis., Methods: We developed a single-cell approach to define and isolate major Th-cell subsets using combinations of chemokine receptors and fluorescence-activated cell sorting. We subsequently confirmed the accuracy of subset enrichment by measuring cytokine production., Measurements and Main Results: Discrimination between Th17 and Th17.1 cells revealed very high percentages of Th17.1 cells in lung lavage in sarcoidosis compared with controls in two separate cohorts. No differences in Th17 or Th1 lavage cells were found compared with controls. Lung lavage Th17.1-cell percentages were also higher than Th1-cell percentages, and approximately 60% of Th17.1-enriched cells produced only IFN-γ., Conclusions: Combined use of surface markers and functional assays to study CD4(+) T cells in sarcoidosis revealed a marked expansion of Th17.1 cells that only produce IFN-γ. These results suggest that Th17.1 cells could be misclassified as Th1 cells and may be the predominant producer of IFN-γ in pulmonary sarcoidosis, challenging the Th1 paradigm of pathogenesis.

Background: The King's Sarcoidosis Questionnaire (KSQ) is a brief questionnaire assessing health status using five modules (General Health Status, Lung, Eyes, Skin, Medication) in patients with sarcoidosis. The KSQ was only validated in one English sarcoidosis cohort., Objective: The aim of this study was to validate the KSQ in a Dutch sarcoidosis population., Methods: The KSQ was translated according to international guidelines and tested in interviews with patients. Consecutive outpatients completed multiple questionnaires twice, two weeks apart. Construct validity, internal consistency and repeatability were determined., Results: Of the 98 patients included 85 had lung, 22 skin and 24 eye disease. There was good construct validity of the KSQ General Health Status module against the World Health Organization Quality of Life-BREF questionnaire. The Medication module correlated weak to moderate with most questionnaires. The correlations with organ-specific questionnaires varied from strong for Eyes (r=0.75), Skin (r=-0.62) to moderate for Lung (r=-0.45 with MRC breathlessness scale). Internal consistency was good for all KSQ modules (Cronbach's α 0.72-0.93). Intraclass correlation coefficients (0.70-0.90) and Bland-Altman plots showed good repeatability of the KSQ., Conclusion: The Dutch KSQ is the first translation of the English KSQ, validated in a Dutch sarcoidosis population.

Abnormal fibrogenic repair response upon alveolar injury is believed to play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). PRM-151 (recombinant human pentraxin-2, also known as serum amyloid P), has been shown to reduce fibrosis in preclinical lung fibrosis models, and was well tolerated with a favourable pharmacokinetic profile in an earlier single-dose phase I study.A randomised, double-blind, placebo-controlled, multiple ascending dose trial was performed to assess the tolerability and pharmacokinetic and pharmacodynamic characteristics of multiple doses of PRM-151 in IPF patients. Subjects in three successive cohorts (1, 5, or 10 mg·kg(-1) versus placebo) received intravenous study drug on days 1, 3, 5, 8 and 15, and were followed-up to day 57.PRM-151 was well tolerated at all dose levels, with no serious adverse reactions. Administration of PRM-151 resulted in two- to eight-fold dose-dependent increases in circulating pentraxin-2 levels. Forced vital capacity and 6-min walk test showed trends towards improvement in the combined PRM-151 dose groups. On high-resolution computed tomography scans, stable or improved lung volume unoccupied by interstitial lung abnormality was noted in some PRM-151 subjects compared to placebo subjects on day 57.The efficacy of PRM-151 in IPF remains to be investigated in dedicated future trials., (Copyright ©ERS 2016.)

Introduction: Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal fibrosing lung disease with a median survival of approximately 3 years after diagnosis. The only medical option to improve survival in IPF is lung transplantation (LTX). The purpose of this study was to evaluate trajectory data of IPF patients listed for LTX and to investigate the survival after LTX., Methods and Results: Data were retrospectively collected from September 1989 until July 2011 of all IPF patients registered for LTX in the Netherlands. Patients were included after revision of the diagnosis based on the criteria set by the ATS/ERS/JRS/ALAT. Trajectory data, clinical data at time of screening, and donor data were collected. In total, 98 IPF patients were listed for LTX. During the waiting list period, 30 % of the patients died. Mean pulmonary artery pressure, 6-min walking distance, and the use of supplemental oxygen were significant predictors of mortality on the waiting list. Fifty-two patients received LTX with a median overall survival after transplantation of 10 years., Conclusions: This study demonstrated a 10-year survival time after LTX in IPF. Furthermore, our study demonstrated a significantly better survival after bilateral LTX in IPF compared to single LTX although bilateral LTX patients were significantly younger.

Background: Impaired regulatory T cell (Treg) function is thought to contribute to ongoing inflammatory responses in sarcoidosis, but underlying mechanisms remain unclear. Moreover, it is not known if increased apoptotic susceptibility of Tregs may contribute to an impaired immunosuppressive function in sarcoidosis. Therefore, the aim of this study is to analyze proportions, phenotype, survival, and apoptotic susceptibility of Tregs in sarcoidosis., Methods: Patients with pulmonary sarcoidosis (n = 58) were included at time of diagnosis. Tregs were analyzed in broncho-alveolar lavage fluid and peripheral blood of patients and healthy controls (HC)., Results: In sarcoidosis patients no evidence was found for a relative deficit of Tregs, neither locally nor systemically. Rather, increased proportions of circulating Tregs were observed, most prominently in patients developing chronic disease. Sarcoidosis circulating Tregs displayed adequate expression of FoxP3, CD25 and CTLA4. Remarkably, in sarcoidosis enhanced CD95 expression on circulating activated CD45RO(+) Tregs was observed compared with HC, and proportions of these cells were significantly increased. Specifically sarcoidosis Tregs--but not Th cells--showed impaired survival compared with HC. Finally, CD95L-mediated apoptosis was enhanced in sarcoidosis Tregs., Conclusion: In untreated patients with active pulmonary sarcoidosis, Tregs show impaired survival and enhanced apoptotic susceptibility towards CD95L. Increased apoptosis likely contributes to the insufficient immunosuppressive function of sarcoidosis Tregs. Further research into this field will help determine whether improvement of Treg survival holds a promising new therapeutic approach for chronic sarcoidosis patients.