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Background: The treatment response to corticosteroids in patients with sarcoidosis is highly variable. CD4 + T cells are central in sarcoid pathogenesis and their phenotype in peripheral blood (PB) associates with disease course. We hypothesized that the phenotype of circulating T cells in patients with sarcoidosis may correlate with the response to prednisone treatment. Therefore, we aimed to correlate frequencies and phenotypes of circulating T cells at baseline with the pulmonary function response at 3 and 12 months during prednisone treatment in patients with pulmonary sarcoidosis., Methods: We used multi-color flow cytometry to quantify activation marker expression on PB T cell populations in 22 treatment-naïve patients and 21 healthy controls (HCs). Pulmonary function tests at baseline, 3 and 12 months were used to measure treatment effect., Results: Patients with sarcoidosis showed an absolute forced vital capacity (FVC) increase of 14.2% predicted (± 10.6, p < 0.0001) between baseline and 3 months. Good response to prednisone (defined as absolute FVC increase of ≥ 10% predicted) was observed in 12 patients. CD4 + memory T cells and regulatory T cells from patients with sarcoidosis displayed an aberrant phenotype at baseline, compared to HCs. Good responders at 3 months had significantly increased baseline proportions of PD-1 + CD4 + memory T cells and PD-1 + regulatory T cells, compared to poor responders and HCs. Moreover, decreased fractions of CD25 + cells and increased fractions of PD-1 + cells within the CD4 + memory T cell population correlated with ≥ 10% FVC increase at 12 months. During treatment, the aberrantly activated phenotype of memory and regulatory T cells reversed., Conclusions: Increased proportions of circulating PD-1 + CD4 + memory T cells and PD-1 + regulatory T cells and decreased proportions of CD25 + CD4 + memory T cells associate with good FVC response to prednisone in pulmonary sarcoidosis, representing promising new blood biomarkers for prednisone efficacy., Trial Registration: NL44805.078.13., (© 2024. The Author(s).)

Rationale: Pulmonary sarcoidosis is generally presumed to be a T-helper cell type 1- and macrophage-driven disease. However, mouse models have recently revealed that chronically inflamed lung tissue can also comprise T follicular helper (Tfh)-like cells and represents a site of active T-cell/B-cell cooperation. Objectives: To assess the role of pulmonary Tfh- and germinal center-like lymphocytes in sarcoidosis. Methods: BAL fluid, lung tissue, and peripheral blood samples from patients with sarcoidosis were analyzed by flow cytometry, immunohistology, RNA sequencing, and in vitro T-cell/B-cell cooperation assays for phenotypic and functional characterization of germinal center-like reactions in inflamed tissue. Measurements and Main Results: We identified a novel population of Tfh-like cells characterized by high expression of the B helper molecules CD40L and IL-21 in BAL of patients with sarcoidosis. Transcriptome analysis further confirmed a phenotype that was both Tfh-like and tissue resident. BAL T cells provided potent help for B cells to differentiate into antibody-producing cells. In lung tissue, we observed large peribronchial infiltrates with T and B cells in close contact, and many IgA + plasmablasts. Most clusters were nonectopic; that is, they did not contain follicular dendritic cells. Patients with sarcoidosis also showed elevated levels of PD-1 high CXCR5 - CD40L high ICOS high Tfh-like cells, but not classical CXCR5 + Tfh cells, in the blood. Conclusions: Active T-cell/B-cell cooperation and local production of potentially pathogenic antibodies in the inflamed lung represents a novel pathomechanism in sarcoidosis and should be considered from both diagnostic and therapeutic perspectives.

Sarcoidosis is a multi-systemic granulomatous disease of unknown origin. Recent research has focused upon the role of autoimmunity in its development and progression. This study aimed to determine and define the disturbance and distribution of T and B cell subsets in the alveolar and peripheral compartments. Thirteen patients were selected for the study [median age, interquartile range (IQR) = 57 years (48-59); 23% were male]. Twelve healthy controls [median age, IQR = 53 years (52-65); 16% male] were also enrolled into the study. Cellular and cytokine patterns were measured using the cytofluorimetric approach. Peripheral CD8 percentages were higher in sarcoidosis patients (SP) than healthy controls (HC) (p = 0.0293), while CD4 percentages were lower (p = 0.0305). SP showed low bronchoalveolar lavage (BAL) percentages of CD19 (p = 0.0004) and CD8 (p = 0.0035), while CD19 + CD5 + CD27 - percentages were higher (p = 0.0213); the same was found for CD4 (p = 0.0396), follicular regulatory T cells (T reg ) (p = 0.0078) and T reg (p < 0.0001) cells. Low T helper type 17 (Th17) percentages were observed in BAL (p = 0.0063) of SP. Peripheral CD4 + C-X-C chemokine receptor (CXCR)5 + CD45RA - ) percentages and follicular T helper cells (Tfh)-like Th1 (Tfh1) percentages (p = 0.0493 and p = 0.0305, respectively) were higher in the SP than HC. Tfh1 percentages and Tfh-like Th2 percentages were lower in BAL than in peripheral blood (p = 0.0370 and p = 0.0078, respectively), while CD4 + C-X-C motif CXCR5 + CD45RA - percentages were higher (p = 0.0011). This is the first study, to our knowledge, to demonstrate a link between an imbalance in circulating and alveolar Tfh cells, especially CCR4-, CXCR3- and CXCR5-expressing Tfh subsets in the development of sarcoidosis. These findings raise questions about the pathogenesis of sarcoidosis and may provide new directions for future clinical studies and treatment strategies., (© 2021 The Authors. Clinical & Experimental Immunology published by John Wiley & Sons Ltd on behalf of British Society for Immunology.)

Background: Pulmonary sarcoidosis (PS) is a noncaseating granulomatous disease of unknown origin. Despite conflicting reports, it is considered that the regulatory T (Treg) cells are functionally impaired in PS, but the underlying mechanisms remain unclear. OX40, a pivotal costimulatory molecule, is essential for T-cell functions and memory development, but its impact on Treg cells is ambiguous., Research Question: Does the OX40 pathway influence the suppressive functions of Treg cells in PS?, Study Design and Methods: Fifty treatment-naïve patients with PS and 30 healthy control participants were recruited for this study. Polychromatic flow cytometry-based immunologic assays were performed to enumerate effector T helper (Th) cells and Treg cells along with their functions. Using real-time polymerase chain reaction analysis, small interfering RNA, and pharmacologic inhibitors, the impact of OX40 on Treg cell function was investigated., Results: We observed enrichment of Th-9 cells perhaps for the first time along with Th-1, Th-17, and Treg cells in patients' BAL fluid (BALF) compared with peripheral blood. However, Treg cells were observed to be functionally defective at the pathological site. We observed higher expression of OX40 on both T effector (CD4 + Foxp3 - ) and Treg (CD4 + Foxp3 + ) cells obtained from the BALF of patients with PS. However, OX40 exerted contrasting impact on these T-cell subsets, enhancing effector T-cell functions (interferon γ, tumor necrosis factor α) while inhibiting Treg cell function (IL-10, transforming growth factor β). OX40 silencing or blocking on Treg cells resulted in restoration of their impaired functions., Interpretation: We propose that inhibiting the OX40 pathway may constitute a therapeutic strategy for controlling inflammatory T cells by restoring Treg cell functions in patients with PS., (Copyright © 2021 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Sarcoidosis and tuberculosis have many clinical and laboratory similarities, which allowed researchers to assume the presence of common pathogenetic mechanisms in the development of both diseases. Recently, much attention has been paid to investigate the autoimmune origins in these pathologies. The aim of this study is to find out the characteristics of the autoinflammatory immune response in sarcoidosis and tuberculosis. In patients with sarcoidosis (n = 93), tuberculosis (n = 28), and in healthy donors (n = 40), the serum anti-MCV concentration was measured by ELISA, and B cell subpopulations were analyzed by flow cytometry. Based on the results obtained, the formula ([B-naïve%]\[B-memory%]) * ([B-CD38%] + [B-CD5%]) / [anti-MCV] was described. The increase in the calculated index by more than 5 units with a sensitivity of 80.00% and a specificity of 93.10% (AUC = 0.926) suggest the presence of the autoimmune component, which is more typical for sarcoidosis, rather than tuberculosis patients and may serve as a diagnostic criterion., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: A Phase I, single-center investigation found that 8 weeks of antimycobacterial therapy improved sarcoidosis FVC. Safety and efficacy assessments have not been performed in a multicenter cohort., Research Question: The objective of this study was to determine the safety and efficacy of antimycobacterial therapy on the physiological and immunologic end points of sarcoidosis., Study Design and Methods: In a double-blind, placebo-controlled, multicenter investigation, patients with pulmonary sarcoidosis were randomly assigned to receive 16 weeks of concomitant levofloxacin, ethambutol, azithromycin, and rifabutin (CLEAR) or matching placebo to investigate the effect on FVC. The primary outcome was a comparison of change in percentage of predicted FVC among patients randomized to receive CLEAR or placebo in addition to their baseline immunosuppressive regimen. Secondary outcomes included 6-min walk distance (6MWD), St. George's Respiratory Questionnaire (SGRQ) score, adverse events, and decrease in mycobacterial early secreted antigenic target of 6 kDa (ESAT-6) immune responses., Results: The intention-to-treat analysis revealed no significant differences in change in FVC among the 49 patients randomized to receive CLEAR (1.1% decrease) compared with the 48 randomized to receive placebo (0.02% increase) (P = .64). Physiological parameters such as the change in 6MWD were likewise similar (P = .91); change in SGRQ favored placebo (-8.0 for placebo vs -1.5 for CLEAR; P = .028). The per-protocol analysis revealed no significant change in FVC at 16 weeks between CLEAR and placebo. There was no significant change in 6MWD (36.4 m vs 6.3 m; P = .24) or SGRQ (-2.3 vs -7.0; P = .14). A decline in ESAT-6 immune responses at 16 weeks was noted among CLEAR-treated patients (P = .0003) but not patients receiving placebo (P = .24)., Interpretation: Despite a significant decline in ESAT-6 immune responses, a 16-week CLEAR regimen provided no physiological benefit in FVC or 6MWD among patients with sarcoidosis., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Rationale: Despite the availability of multi-"omics" strategies, insights into the etiology and pathogenesis of sarcoidosis have been elusive. This is partly due to the lack of reliable preclinical models and a paucity of validated biomarkers. As granulomas are a key feature of sarcoidosis, we speculate that direct genomic interrogation of sarcoid tissues, may lead to identification of dysregulated gene pathways or biomarker signatures., Objective: To facilitate the development sarcoidosis genomic biomarkers by gene expression profiling of sarcoidosis granulomas in lung and lymph node tissues (most commonly affected organs) and comparison to infectious granulomas (coccidiodomycosis and tuberculosis)., Methods: Transcriptomic profiles of immune-related gene from micro-dissected sarcoidosis granulomas within lung and mediastinal lymph node tissues and compared to infectious granulomas from paraffin-embedded blocks. Differentially-expressed genes (DEGs) were profiled, compared among the three granulomatous diseases and analyzed for functional enrichment pathways., Results: Despite histologic similarities, DEGs and pathway enrichment markedly differed in sarcoidosis granulomas from lymph nodes and lung. Lymph nodes showed a clear immunological response, whereas a structural regenerative response was observed in lung. Sarcoidosis granuloma gene expression data corroborated previously reported genomic biomarkers (STAB1, HBEGF, and NOTCH4), excluded others and identified new genomic markers present in lung and lymph nodes, ADAMTS1, NPR1 and CXCL2. Comparisons between sarcoidosis and pathogen granulomas identified pathway divergences and commonalities at gene expression level., Conclusion: These findings suggest the importance of tissue and disease-specificity evaluation when exploring sarcoidosis genomic markers. This relevant translational information in sarcoidosis and other two histopathological similar infections provides meaningful specific genomic-derived biomarkers for sarcoidosis diagnosis and prognosis.

Background: Sarcoidosis is a multisystemic granulomatous disease with still unknown etiology. Our previous studies showed a significantly higher percentage of CD34 + cells in the peripheral blood in patients with sarcoidosis (SA) compared to the control group. The objective of the present study was to characterized of the CD34 + cell population in peripheral blood in patients with SA with reference to the control group. Moreover in patients with SA, fibrocytes and endothelial cells were analysed and their relationship to the fibrosis process based on assessment of diffusing capacity for carbon monoxide (DLCO)., Methods: Data from patients diagnosed with SA at Military Institute of Medicine (Warsaw, Poland) between January 2018 and December 2019 were collected and analysed ongoing basis. Peripheral blood was collected from 26 patients with newly diagnosed pulmonary SA and 16 healthy subjects. The immunomagnetic method and flow cytometry were used. Among the CD34+ progenitor cells were assessed: low-differentiated cells, hematopoietic progenitor cells and endothelial progenitor cells. The Statistica 12.0 software was used for a statistical analysis., Results: We observed a significantly higher percentage of low-differentiated cells (13.8 vs. 2.3, P = 0.001) and endothelial cells (0.3 vs. 0.0, P = 0.001) in patients with SA compared to the control group. In the study group the median proportion of fibrocytes was 1.877% (0.983-2.340) in patients with DLCO< 80%, while in patients with DLCO> 80% was 0.795% (0.139-1.951) (P = 0.72). The median proportion of endothelial progenitor cells was higher in patients with DLCO< 80%: 0.889% (0.391-1.741), than in patients with DLCO> 80%: 0.451% (0.177-0.857) (P = 0.44)., Conclusions: In conclusion we demonstrated for the first time the immunophenotype of peripheral CD34 + cells with the degree of their differentiation. The study confirmed the involvement of low differentiated cells and endothelial cells in patients with SA.

Rationale: A subpopulation of B cells (age-associated B cells [ABCs]) is increased in mice and humans with infections or autoimmune diseases. Because depletion of these cells might be valuable in patients with certain lung diseases, the goal was to find out if ABC-like cells were at elevated levels in such patients. Objectives: To measure ABC-like cell percentages in patients with lung granulomatous diseases. Methods: Peripheral blood and BAL cells from patients with sarcoidosis, beryllium sensitivity, or hypersensitivity pneumonitis and healthy subjects were analyzed for the percentage of B cells that were ABC-like, defined by expression of CD11c, low levels of CD21, FcRL 1-5 (Fc receptor-like protein 1-5) expression, and, in some cases, T-bet. Measurements and Main Results: ABC-like cells in blood were at low percentages in healthy subjects and higher percentages in patients with sarcoidosis as well as at high percentages among BAL cells of patients with sarcoidosis, beryllium disease, and hypersensitivity pneumonitis. Treatment of patients with sarcoidosis led to reduced percentages of ABC-like cells in blood. Conclusions: Increased levels of ABC-like cells in patients with sarcoidosis may be useful in diagnosis. The increase in percentage of ABC-like cells in patients with lung granulomatous diseases and decrease in treated patients suggests that depletion of these cells may be valuable.

Background: Sarcoidosis is a chronic inflammatory disease of unknown cause characterized by granuloma formation. Mechanisms for chronic persistence of granulomas are unknown. Matrix Metalloproteinase-12 (MMP12) degrades extracellular matrix elastin and enables infiltration of immune cells responsible for inflammation and granuloma formation. Previous studies report increased MMP12 in sarcoidosis patients and association between MMP12 expression and disease severity. We also observed elevated MMP12 in our multiwall carbon nanotube (MWCNT) murine model of granulomatous inflammation. Here we hypothesized that MMP12 is important to acute and late phases of granuloma pathogenesis. To test this hypothesis, we analyzed granulomatous and inflammatory responses of Mmp12 knock-out (KO) mice at 10 (acute) and 60 days (late) after MWCNT instillation., Methods: C57BL/6 (wildtype) and Mmp12 KO mice underwent oropharyngeal instillation of MWCNT. Lungs were harvested at 3, 10, 20, and 60 days post instillation for evaluation of MMP12 expression and granulomatous changes. Bronchoalveolar lavage (BAL) cells were analyzed 60 days after MWCNT instillation for expression of mediators thought to play a role in sarcoid granulomatosis: peroxisome proliferator-activated receptor-gamma (PPARγ), interferon-gamma (IFN-γ), and CCL2 (MCP-1)., Results: Pulmonary granuloma appearance at 10 days after MWCNT instillation showed no differences between wildtype and Mmp12 KO mice. In contrast, by 60 days after MWCNT instillation, Mmp12 KO mice revealed markedly attenuated granuloma formation together with elevated PPARγ and reduced IFNγ expression in BAL cells compared to wildtype. Unexpectedly, Mmp12 KO mice further demonstrated increased alveolar macrophages with increased CCL2 at 60 days., Conclusions: The striking reduction of granuloma formation at day 60 in Mmp12 KO mice suggests that MMP12 is required to maintain chronic granuloma pathophysiology. The increased PPARγ and decreased IFNγ findings suggest that these mediators also may be involved since previous studies have shown that PPARγ suppresses IFNγ and PPARγ deficiency amplifies granuloma formation. Interestingly, a role of MMP12 in granuloma resolution is also suggested by increases in both macrophage influx and CCL2. Overall, our results strongly implicate MMP12 as a key factor in granuloma persistence and as a possible therapeutic target in chronic pulmonary sarcoidosis., (Copyright © 2020 Mohan, Neequaye, Malur, Soliman, McPeek, Leffler, Ogburn, Tokarz, Knudson, Gharib, Schnapp, Barna and Thomassen.)

The inability to effectively model sarcoidosis in the laboratory or in animals continues to hinder the discovery and translation of new, targeted treatments. The granuloma is the signature pathological hallmark of sarcoidosis, yet there are significant knowledge gaps that exist with regard to how granulomas form. Significant progress toward improved therapeutic and prognostic strategies in sarcoidosis hinges on tractable experimental models that recapitulate the process of granuloma formation in sarcoidosis and allow for mechanistic insights into the molecular events involved. Through its inherent representation of the complex genetics underpinning immune cell dysregulation in sarcoidosis, a recently developed in vitro human granuloma model holds promise in providing detailed mechanistic insight into sarcoidosis-specific disease regulating pathways at play during early stages of granuloma formation. The purpose of this review is to critically evaluate current sarcoidosis models and assess their potential to progress the field toward the goal of improved therapies in this disease. We conclude with the potential integrated use of preclinical models to accelerate progress toward identifying and testing new drugs and drug combinations that can be rapidly brought to clinical trials., (Copyright © 2020 Locke, Schlesinger and Crouser.)

Background: Interferon-gamma (IFN-γ) is a key mediator of sarcoidosis-related granulomatous inflammation. Previous findings of IFN-γ-producing Th17 cells in bronchoalveolar lavage fluid from sarcoidosis patients invokes the transition of Th17.0 cells to Th17.1 cells in the disease's pathogenesis. Since the T-bet transcription factor is crucial for this transition, the goal of this study was to determine if T-bet expression in Th17.0 cells reflects the extent of granulomatous inflammation in sarcoidosis patients as assessed by clinical outcomes. Methods: Using a case-control study design, we identified two groups of sarcoidosis subjects (total N = 43) with pulmonary function tests (PFTs) that either (1) changed (increased or decreased) longitudinally or (2) were stable. We used flow cytometry to measure the transcription factors T-bet and RORγt in Th1, Th17.0, and Th17.1 cell subsets defined by CCR6, CCR4 and CXCR3 in blood samples. We compared the percentages of T-bet + cells in RORγt + Th17.0 cells (defined as CCR6 + CCR4 + CXCR3 - ) based on subjects' PFT group. We also assessed the relationship between the direction of change in PFTs with the changes in %T-bet + frequencies using mixed effects modeling. Results: We found that T-bet expression in subjects' RORγt + Th17.0 cells varied based on clinical outcome. The T-bet + percentage of RORγt + Th17.0 cells was higher in the cases (subject group with PFT changes) as compared to controls (stable group) (27 vs. 16%, p = 0.0040). In comparisons before and after subjects' PFT changes, the T-bet + frequency of RORγt + Th17.0 cells increased or decreased in the opposite direction of the PFT change. The percentage of these T-bet + cells was also higher in those with greater numbers of involved organs. Serum levels of interferon-γ-induced chemokines, CXCL9, CXCL10, and CXCL11, and whole blood gene expression of IFN-γ-related genes including GBP1, TAP1 , and JAK2 were independently positively associated with the T-bet + frequencies of RORγt + Th17.0 cells. Conclusions: These data suggest that expression of T-bet in Th17.0 cells could reflect the extent of granulomatous inflammation in sarcoidosis patients because they represent a transition state leading to the Th17.1 cell phenotype. These findings indicate that Th17 plasticity may be part of the disease paradigm., (Copyright © 2020 Arger, Machiraju, Allen, Woodruff and Koth.)

Pulmonary sarcoidosis is characterized by an exaggerated CD4 + T cell response and formation of non-necrotizing granulomas. Tumour necrosis factor α (TNF-α) is regarded as crucial for granuloma formation and TNF-α inhibitors offer a third-line treatment option for patients not responding to conventional treatment. However, not all patients benefit from treatment, and an optimal dose and treatment duration have not been established. Insight into the influence of TNF-α inhibitors on lung immune cells may provide clues as to what drives inflammation in sarcoidosis and improve our understanding of treatment outcomes. To evaluate the effects of treatment with the TNF-α inhibitor infliximab on lung immune cells and clinical features of the patients, 13 patients with sarcoidosis refractory to conventional treatment were assessed with bronchoalveolar lavage (BAL), spirometry and computerized tomography (CT) scan closely adjacent to the start of infliximab treatment. These investigations were repeated after 6 months of treatment. Treatment with TNF-α inhibitor infliximab was well tolerated with no adverse events, except for one patient who developed a probable adverse event with liver toxicity. Ten patients were classified as responders, having a reduced CD4/CD8 ratio, a decreased percentage of CD4 + T cells expressing the activation marker CD69 and number of mast cells (P < 0·05 for all). The percentage of T regulatory cells (T regs ), defined as forkhead box P3 + CD4 + T cells decreased in most patients. In conclusion, six months of infliximab treatment in patients with sarcoidosis led to signs of decreased CD4 + T cell alveolitis and decreased mastocytosis in the lungs of responders., (© 2020 The Authors. Clinical & Experimental Immunology published by John Wiley & Sons Ltd on behalf of British Society for Immunology.)

Pulmonary sarcoidosis and chronic beryllium disease (CBD) are inflammatory granulomatous lung diseases defined by the presence of non-caseating granulomas in the lung. CBD results from beryllium exposure in the workplace, while the cause of sarcoidosis remains unknown. CBD and sarcoidosis are both immune-mediated diseases that involve Th1-polarized inflammation in the lung. Beryllium exposure induces trafficking of dendritic cells to the lung in a mechanism dependent on MyD88 and IL-1α. B cells are also recruited to the lung in a MyD88 dependent manner after beryllium exposure in order to protect the lung from beryllium-induced injury. Similar to most immune-mediated diseases, disease susceptibility in CBD and sarcoidosis is driven by the expression of certain MHCII molecules, primarily HLA-DPB1 in CBD and several HLA-DRB1 alleles in sarcoidosis. One of the defining features of both CBD and sarcoidosis is an infiltration of activated CD4+ T cells in the lung. CD4+ T cells in the bronchoalveolar lavage (BAL) of CBD and sarcoidosis patients are highly Th1 polarized, and there is a significant increase in inflammatory Th1 cytokines present in the BAL fluid. In sarcoidosis, there is also a significant population of Th17 cells in the lungs that is not present in CBD. Due to persistent antigen exposure and chronic inflammation in the lung, these activated CD4+ T cells often display either an exhausted or anergic phenotype. Evidence suggests that these T cells are responding to common antigens in the lung. In CBD there is an expansion of beryllium-responsive TRBV5.1+ TCRs expressed on pathogenic CD4+ T cells derived from the BAL of CBD patients that react with endogenous human peptides derived from the plexin A protein. In an acute form of sarcoidosis, there are expansions of specific TRAV12-1/TRBV2 T cell receptors expressed on BAL CD4+ T cells, indicating that these T cells are trafficking to and expanding in the lung in response to common antigens. The specificity of these pathogenic CD4+T cells in sarcoidosis are currently unknown., (Copyright © 2020 Greaves, Atif and Fontenot.)

Sarcoidosis is a systemic granulomatous disease that develops due to the Th1, Th17 and Treg lymphocytes disturbance. There is an assumption, that B cells and follicular T-helper (Tfh) cells may play an important role in this disorder, as well as in several other autoimmune diseases. The aim of this study was to determine CD19+ B cells subset distribution in the peripheral blood and to define disturbance in the circulating Tfh cells subsets in patients with sarcoidosis. The prospective comparative study was performed in 2016-2018, where peripheral blood B cell subsets and circulating Tfh cell subsets were analyzed in 37 patients with primarily diagnosed sarcoidosis and 35 healthy donors using multicolor flow cytometry. In the results of our study we found the altered distribution of peripheral B cell subsets with a predominance of "naïve" (IgD + CD27-) and activated B cell (Bm2 and Bm2') subsets and a decreased frequency of memory cell (IgD+ CD27+ and IgD- CD27+) in peripheral blood of sarcoidosis patients was demonstrated. Moreover, we found that in sarcoidosis patients there are increased levels of B cell subsets, which were previously shown to display regulatory capacities (CD24+++ CD38+++ and CD5 + CD27-). Next, a significantly higher proportion of CXCR5-expressing CD45RA - CCR7+ Th cells in patients with sarcoidosis in comparison to the healthy controls was revealed, that represents the expansion of this memory Th cell subset in the disease. This is the first study to demonstrate the association between the development of sarcoidosis and imbalance of circulating Tfh cells, especially CCR4- and CXCR3-expressing Tfh subsets. Finally, based on our data we can assume that B cells and Tfh2- and Tfh17-like cells - most effective cell type in supporting B-cell activity, particularly in antibody production - may be involved in the occurrence and development of sarcoidosis and in several other autoimmune conditions. Therefore, we can consider these results as a new evidence of the autoimmune mechanisms in the sarcoidosis development.

Respiratory diseases compromise the health of millions of people all over the world and are strongly linked to the immune dysfunction. CD4+FOXP3+ T regulatory cells, also known as Tregs, have a central role maintaining tissue homeostasis during immune responses. Their activity and clinical impact have been widely studied in different clinical conditions including autoimmune diseases, inflammatory conditions, and cancer, amongst others. Tregs express transcription factor forkhead box P3 (FOXP3), which allows regulation of the immune response through anti-inflammatory cytokines such as IL-10 or transforming growth factor beta (TGF- β ) and direct cell-to-cell interaction. Maintenance of immune tolerance is achieved via modulation of effector CD4+ T helper 1, 2 or 17 (Th1, Th2, Th17) cells by Tregs. This review highlights the recent progress in the understanding of Tregs in different disorders of the respiratory system., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2019 Rani Singh et al.)

Sarcoidosis is a systemic granulomatous disease associated with Th1/ regulatory T cells (Treg) paradigm. PI3K/Akt signaling, critical for maintaining Treg's homeostasis, is aberrantly activated in sarcoidosis patients. Here we tested the role of the PI3K inhibitors, LY294002 and BKM120, in immune modulation in experimental pulmonary sarcoidosis, concerning Th1/Th17/Treg immune profile detected by fluorescence-activated cell sorting analysis or quantitative polymerase chain reaction, as well as the effect on Treg's suppressive functions. Our investigation showed abnormal activation of PI3K/Akt signaling both in lung and Treg in pulmonary sarcoidosis, along with decreased frequency and damaged function of Treg. Blockage of PI3K suppressed this signaling in Treg, rebalanced Th1/Treg, inhibited the production of inflammatory cytokines, and enhanced Treg's function. These results demonstrate the key role of the PI3K/Akt signaling in regulating Th1/Th2 rebalances and indicates that PI3K/Akt signaling is critical for the optimal Treg responses in pulmonary sarcoidosis. Thus, PI3K inhibitors have potential for therapeutic translation, and can be candidate for add-on drugs to treat pulmonary sarcoidosis., (© 2019 Wiley Periodicals, Inc.)

Although the pathogenesis of sarcoidosis is not fully understood, immunological characterization has elucidated highly polarized expression of the type 1 T helper cell response. Mucosal-associated invariant T (MAIT) cells are innate T cells that recognize bacterial riboflavin and rapidly produce cytokines such as interferon γ and tumor necrosis factor α. We prospectively evaluated the proportion of MAIT cells and the expression levels of cell surface markers in peripheral blood from 40 sarcoidosis patients and 28 healthy controls. MAIT cells in bronchoalveolar lavage fluid (BALF) were also examined in 12 sarcoidosis patients. In peripheral blood, the proportion of MAIT cells was lower (P = 0.0002), but the expression levels of CD69 and programmed death 1 on MAIT cells were higher in sarcoidosis patients than in healthy controls. Moreover, CD69 expression levels were significantly correlated with clinical biomarkers. Sarcoidosis patients with parenchymal infiltration in the lungs showed a significantly higher proportion and number of MAIT cells in BALF compared to patients without parenchymal infiltration. CD69 expression levels on MAIT cells in BALF were higher than levels in peripheral blood. The activation status of MAIT cells might reflect the disease activity of sarcoidosis. Therefore, it is a potential target for sarcoidosis treatment.

The etiology of sarcoidosis is unknown. In this study, Propionibacterium acnes (PA) was used to induce sarcoidosis-like granulomatous inflammation in a mouse model. Wild-Type (WT) C57BL/6 mice were divided into three groups: (1) WT-PA group; (2) WT-PA + Incomplete Freund's Adjuvant (IFA) group; and (3) WT-PBS group. Loose granuloma formation was observed in the lungs on day 56 in the WT-PA and WT-PA + IFA groups. The proportions of peripheral Th17 cells in the WT-PA ( p = 0.0004) and WT-PA + IFA groups ( p = 0.0005) were significantly higher than that in the WT-PBS group. The proportions of peripheral Treg cells in the WT-PA ( p < 0.0001) and WT-PA + IFA groups ( p < 0.0001) were lower than that in the WT-PBS group. Then, to explore the mechanism of IL-17, Wild-Type (WT) C57BL/6 mice were divided into three groups: (1) WT-PBS group (2) WT-PA group; (3) WT-PA + mouse IL-17A neutralizing antibody (IL-17Ab) group. IL-17A gene knockout mice (KO) were divided into two groups: (1) KO -PA group; (2) KO-PBS group. The KO-PA and WT-PA + IL-17Ab groups showed reduced inflammation and no loose granuloma formation on day 56. As compared to the WT-PA group, the ratio of peripheral Th17 in the KO-PA ( p < 0.0001) and WT-PA + IL-17Ab groups ( p < 0.0001) decreased, while the ratio of peripheral Treg in the KO-PA ( p < 0.0001) and WT-PA + IL-17Ab ( p = 0.0069) groups increased on day 56. Hence, PA can be used to establish a mouse model of sarcoidosis-like granuloma. IL-17A plays an important role in experimental sarcoidosis-like granuloma formation.

Despite more than a century of research, the causative agent(s) in sarcoidosis, a heterogeneous granulomatous disorder mainly affecting the lungs, remain(s) elusive. Following identification of genetic factors underlying different clinical phenotypes, increased understanding of CD4 + T-cell immunology, which is believed to be central to sarcoid pathogenesis, as well as the role of B-cells and other cells bridging innate and adaptive immunity, contributes to novel insights into the mechanistic pathways influencing disease resolution or chronicity. Hopefully, new perspectives and state-of-the-art technology will help to shed light on the still-elusive enigma of sarcoid aetiology. This perspective article highlights a number of recent advances in the search for antigenic targets in sarcoidosis, as well as the main arguments for sarcoidosis as a spectrum of autoimmune conditions, either as a result of an external (microbial) trigger and/or due to defective control mechanisms regulating the balance between T-cell activation and inhibition., Competing Interests: Conflict of interest: Y. Kaiser has nothing to disclose. Conflict of interest: A. Eklund has nothing to disclose. Conflict of interest: J. Grunewald has nothing to disclose., (Copyright ©ERS 2019.)

Sarcoidosis is a rare inflammatory disease characterized by the development of granulomas in various organs, especially in the lungs and lymph nodes. Clinics of the disease largely depends on the organ involved and may range from mild symptoms to life threatening manifestations. Over the last two decades, significant advances in the diagnosis, clinical assessment and treatment of sarcoidosis have been achieved, however, the precise etiology of this disease remains unknown. Current evidence suggests that, in genetically predisposed individuals, an excessive immune response to unknown antigen/s is crucial for the development of sarcoidosis. Epidemiological and microbiological studies suggest that, at least in a fraction of patients, microbes or their products may trigger the immune response leading to sarcoid granuloma formation. In this article, we discuss the scientific evidence on the interaction of microbes with immune cells that may be implicated in the immunopathogenesis of sarcoidosis, and highlight recent studies exploring potential implications of human microbiota in the pathogenesis and the clinical course of sarcoidosis.

Genetic susceptibility for sarcoidosis and Löfgren's syndrome (LS) has been associated with prognosis. Human leukocyte antigen (HLA)-DRB1*03 is over-represented in LS, and is associated with a good prognosis, whereas HLA-DRB1*15-positive patients have a more chronic course of sarcoidosis. These HLA-DRB1 types can be easily tagged by single nucleotide polymorphisms (SNPs). Our aim was to evaluate the association between these tag SNPs and bronchoalveolar lavage (BAL) characteristics. In 29 patients, both complete HLA-DRB1* locus genotyping and SNP tagging was performed in parallel. HLA-DRB1 type was inferred from the presence of *03 tag rs2040410 allele A and referred to as *03. HLA-DRB1*15 was inferred from the presence of tag SNP rs3135388 allele A and referred to as *15. For BAL analysis, 122 patients with LS and 165 patients with non-LS sarcoidosis were included. BAL lymphocyte subsets were analyzed by flow cytometry. The presence of tag SNPs completely corresponded with HLA-DRB1*03/*15 genotypes in all 29 patients in whom both HLA-DRB1* genotyping and SNP tagging was performed. In all patients together, *03 + /*15 - patients showed a higher CD4 + /CD8 + ratio than *03 - /*15 + (P = 0·004) and *03 - /*15 - (P = 0·001). LS patients with *03 + /*15 - had a lower BAL lymphocyte count compared to *03 - /*15 +  patients (P = 0·011). Non-LS sarcoidosis patients with *03 + /*15 - patients showed a decreased CD103 + CD4 + /CD4 + ratio compared to *03 - /*15 +  patients (P = 0·045) and *03 - /*15 - patients (P = 0·018). We found that HLA-DRB1*03 and HLA-DRB1*15 can be approximated by genotyping of tag SNPs and corresponds with the degree of lymphocytosis and cell phenotypes in BAL in both LS and non-LS sarcoidosis patients., (© 2018 British Society for Immunology.)

Background: Diffuse lung diseases (DLD) are characterized by different immunophenotypes in the bronchoalveolar lavage fluid (BALF). We aimed to evaluate the diagnostic value of BALF NK and NKT cell counts of patients with DLD and lymphocytic alveolitis., Methods: We assessed 202 patients with DLD, who underwent BALF immunophenotyping. Samples were routinely processed by flow cytometry and lymphocyte subsets were compared between patients with sarcoidosis (n = 106), hypersensitivity pneumonitis (HP; n = 53), and other DLDs (n = 43). We compared absolute counts and percentages of NK and NKT cells between patients with HP versus the remaining DLD patients. To assess the accuracy of BALF lymphocyte subsets in the diagnosis of HP, we calculated the respective areas under the receiver operating characteristic curves (AUC-ROC)., Results: Patients with HP had significantly higher numbers of BALF NK cells, and its percentage was significantly associated with a higher odds of HP, even after adjustment for the NKT and CD8 + cells. For the absolute number of BALF NK cells, we found an AUC-ROC of 0.76 (95%CI = 0.68-0.84) when comparing patients with HP versus the remaining DLD. The cut-offs of 2000 NK cells/mL and of 2.4% NK cells in the BALF had a specificity and a negative predictive value over 80% for the diagnosis of HP. BALF NK cells absolute counts were significantly higher in HP patients with a restrictive pattern. No such differences were observed for NKT cells., Conclusions: BALF NK immunophenotyping may be a helpful adjunct to the diagnostic work-up of DLD, particularly in the differential diagnosis of HP.

The mechanisms underlying abnormal granuloma formation in patients with sarcoidosis are complex and remain poorly understood. A novel in vitro human granuloma model was used to determine the molecular mechanisms of granuloma genesis in patients with sarcoidosis in response to putative disease-causing mycobacterial antigens. Peripheral blood mononuclear cells (PBMCs) from patients with active sarcoidosis and from normal, disease-free control subjects were incubated for 7 days with purified protein derivative-coated polystyrene beads. Molecular responses, as reflected by differential expression of genes, extracellular cytokine patterns, and cell surface receptor expression, were analyzed. Unbiased systems biology approaches were used to identify signaling pathways engaged during granuloma formation. Model findings were compared with human lung and mediastinal lymph node gene expression profiles. Compared with identically treated PBMCs of control subjects (n = 5), purified protein derivative-treated sarcoidosis PBMCs (n = 6) were distinguished by the formation of cellular aggregates resembling granulomas. Ingenuity Pathway Analysis of differential expression gene patterns identified molecular pathways that are primarily regulated by IL-13, which promotes alternatively activated (M2) macrophage polarization. M2 polarization was further demonstrated by immunohistochemistry performed on the in vitro sarcoidosis granuloma-like structures. IL-13-regulated gene pathways were confirmed in human sarcoidosis lung and mediastinal lymph node tissues. The in vitro human sarcoidosis granuloma model provides novel insights into early granuloma formation, particularly IL-13 regulation of molecular networks that regulate M2 macrophage polarization. M2 macrophages are predisposed to aggregation and multinucleated giant cell formation, which are characteristic features of sarcoidosis granulomas. Clinical trial registered with www.clinicaltrials.gov (NCT01857401).

Epigenetic marks are likely to explain variability of response to antigen in granulomatous lung disease. The objective of this study was to identify DNA methylation and gene expression changes associated with chronic beryllium disease (CBD) and sarcoidosis in lung cells obtained by BAL. BAL cells from CBD (n = 8), beryllium-sensitized (n = 8), sarcoidosis (n = 8), and additional progressive sarcoidosis (n = 9) and remitting (n = 15) sarcoidosis were profiled on the Illumina 450k methylation and Affymetrix/Agilent gene expression microarrays. Statistical analyses were performed to identify DNA methylation and gene expression changes associated with CBD, sarcoidosis, and disease progression in sarcoidosis. DNA methylation array findings were validated by pyrosequencing. We identified 52,860 significant (P < 0.005 and q < 0.05) CpGs associated with CBD; 2,726 CpGs near 1,944 unique genes have greater than 25% methylation change. A total of 69% of differentially methylated genes are significantly (q < 0.05) differentially expressed in CBD, with many canonical inverse relationships of methylation and expression in genes critical to T-helper cell type 1 differentiation, chemokines and their receptors, and other genes involved in immunity. Testing of these CBD-associated CpGs in sarcoidosis reveals that methylation changes only approach significance, but are methylated in the same direction, suggesting similarities between the two diseases with more heterogeneity in sarcoidosis that limits power with the current sample size. Analysis of progressive versus remitting sarcoidosis identified 15,215 CpGs (P < 0.005 and q < 0.05), but only 801 of them have greater than 5% methylation change, demonstrating that DNA methylation marks of disease progression changes are more subtle. Our study highlights the significance of epigenetic marks in lung immune response in granulomatous lung disease.

Clinical and radiological features of tuberculosis and sarcoidosis are quite overlapping, and therefore, a diagnostic dilemma often persists. There are no commonly accepted criteria for the diagnosis of sarcoidosis due to the lack of data on the etiology of the disease. The exclusion of tuberculosis in every patient with suspected sarcoidosis is a mandatory stage of diagnosis, especially in countries with a high burden of tuberculosis. A prospective study was conducted with two groups of patients: group I (n = 50)-patients with pulmonary sarcoidosis established according to standard criteria; group II (n = 28)-patients with pulmonary tuberculosis with bacterial excretion. The control group (n = 24) was presented by healthy subjects. The examination complex included x-ray, bacteriological, immunological (Mantoux test with 2 TE, TB.SPOT test), and histological methods. All patients and healthy subjects were assessed for immune complexes with the use of the dynamic light scattering (DLS) method and adding of "healthy lung tissue extract" antigens and specific tuberculosis antigens ESAT-6 and SFP-10 in vitro. Significant differences were found in determining specific immune complexes in patients with pulmonary sarcoidosis and pulmonary tuberculosis. Registration of specific immune complex formation with "healthy lung tissue extract" in 100% cases may indicate the autoimmune nature of sarcoidosis. The absence of the immune complex formation in response to ESAT-6/SFP-10 antigens can be used for the differential diagnosis of two diseases. The diagnostic significance of the DLS method was 100% for sarcoidosis and 92.2% for tuberculosis. The data obtained in the study allows not only understanding the etiology of sarcoidosis, but also obtaining new criteria for the differential diagnosis of tuberculosis and pulmonary sarcoidosis.

The feature of pulmonary sarcoidosis is characterized by a Th1/Th17/regulatory T cells (Tregs) -driven inflammatory process in lung, resulting in noncaseating granulomas containing CD4+ T cells. Tregs increase in both lung and peripheral blood, with damaged immunoregulatory function. The current study investigated the effects of IL33 or anti-IL23 antibody on restoring the homeostasis and functions of Tregs in mycobacterial superoxide dismutase A (SodA)-induced pulmonary sarcoidosis. IL33 or anti-IL23 antibody was administered to mice with late-stage pulmonary sarcoidosis. The levels of Th1/Th17/Tregs and Tregs' suppressive functions were detected by fluorescence activated cell sorting (FACS) analysis or qPCR. The expressions of key proteins in PI3K/Akt/mTOR and TGF-β/Smad2/Smad3 signaling pathways were tested by western blot. IL33 administration was associated with the rebalance of Th1/Th2 and Tregs, as well as a superior suppressor activity of Tregs on effector T cells in sarcoidosis, probably through increasing ST2 expressions on Tregs, along with the suppression of PI3K/Akt/mTOR and TGF-β/Smad2/Smad3 signaling pathways. Small dose of anti-IL23 antibody independently improved Th1/Th2 bias, but had limited effects on the homeostasis and ST2 expressions on Tregs. These results suggested a major anti-inflammatory ability of IL33 to ameliorate the disturbance of Th1/Th2 and Tregs in pulmonary sarcoidosis, and provided rationales for further strategies of targeting the IL33/ST2 signals in the treatment of pulmonary sarcoidosis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Sarcoidosis is characterized by exaggerated immune response to unknown agent and can affect different organs. One of the main players in the pathology of the disease are regulatory T cells (Tregs), however, up to date the mechanisms of the possible molecular alterations of this particular cell subset are not known., Methods: In the current study we looked for the global transcriptomic changes of miRNAs, using predefined array, and mRNAs (RNA seq analysis) of Tregs of patients with the most predominant form of the disease - acute pulmonary sarcoidosis (PS). For this purpose sorted CD4+/CD25+/CD127- Tregs from peripheral blood (PB) and CD4+/CD25 + Tregs from bronchoalveolar lavage (BAL) were used., Results: MiRNA analysis revealed that Tregs isolated from PB and BAL display significantly different miRNA profile, suggesting an important role of the pulmonary microenvironment in creating these changes. Among disease-related miRNAs of PB Tregs we identified miR-155 and miR-223. Moreover, looking at the global transcriptome of PB Tregs, we recognized alterations in TLR-2 signaling pathway and in the downstream of NF-κB apoptosis and proliferation signals. However, induction of TLR-2 expression was found not only in Tregs, but also in the heterogeneous population of peripheral blood mononuclear cells (PBMC) as well as two PBMC subpopulations (CD4+/CD25-and CD4-/CD25-) of patients with PS. This indicates that activation of TLR signaling pathway in sarcoidosis does not occur only in Tregs., Conclusion: Our findings offer a deeper insight into the molecular mechanisms of Tregs reduced suppression and increased apoptosis in patients with PS. Based on the current results, future studies should focus on possible therapeutic effect of TLR-2 signaling inhibition., (Copyright © 2018. Published by Elsevier Ltd.)

Bronchoalveolar lavage (BAL) is one of the tests for orientation in the diagnosis of diffuse parenchymal lung disease. Lymphocyte subpopulation study by flow cytometry in the BAL is part of the criteria for the diagnosis of sarcoidosis. We investigated the feasibility of T lymphocyte immunophenotyping in BAL on a new automaton: AQUIOS CL®, a closed access cytometer with fully automated process designed for blood samples. Repeatability and contamination studies showed acceptable results (variation coefficients <5% and contamination indices <1%). We also compared BAL immunophenotyping results performed on AQUIOS CL® with those performed with an open access cytometer: Navios®. The correlation coefficient r is close to 1 on the studied parameters. The number of unacceptable measurement deviations is <5% and does not affect the biological interpretation of the results indicating a good correlation between the two automata. These results show that immunophenotyping in BAL is feasible on AQUIOS CL®., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Thoracic sarcoidosis is the most common form of sarcoidosis, encompassing a heterogeneous group of patients with a wide range of clinical features and associated outcomes. The distinction between isolated thoracic lymphadenopathy and pulmonary involvement matters. Morbidity is often higher, and long-term outcomes are worse for the latter. Although inflammatory infiltrates in pulmonary sarcoidosis may resolve, persistent disease activity is common and can result in lung fibrosis. Given the distinct clinical features and natural history of pulmonary sarcoidosis, its pathogenesis may differ in important ways from other sarcoidosis manifestations. This review highlights recent advances in the pathogenesis of pulmonary sarcoidosis, including the nature of the sarcoidosis antigen, the role of serum amyloid A and other host factors that contribute to alterations in innate immunity, factors that shape adaptive T-cell profiles in the lung, and how these mechanisms influence the maintenance of granulomatous inflammation in sarcoidosis. We discuss questions raised by recent findings, including the role of innate immunity in the pathogenesis, the meaning of immune cell exhaustion, and mechanisms that may contribute to lung fibrosis in sarcoidosis. We conclude with a reflection on when and how immunosuppressive therapies may be helpful for pulmonary sarcoidosis, a consideration of nonpharmacologic management strategies, and a survey of potential novel therapeutic targets for this vexing disease., (Copyright © 2017 American College of Chest Physicians. All rights reserved.)

Background: The role of CD4 + T cells in the immunopathogenesis of pulmonary sarcoidosis is well-established, while less is known about the phenotype and function of CD8 + cytolytic T cells (CTLs)., Methods: CD8 + CTLs were explored in peripheral blood and bronchoalveolar lavage (BAL) samples obtained from up to 25 patients with sarcoidosis and 25 healthy controls. The proportion of CTLs was assessed by the expression of cytolytic effector molecules perforin, granzyme B and granulysin in CD8 + T cells, using flow cytometry. Cytolytic function in blood lymphocytes was assessed using a standard 51 Cr-release assay. Patients with Löfgren´s syndrome (LS) and an acute disease onset, were compared to non-LS patients with an insidious onset., Results: Higher proportions of peripheral CD8 + CTLs expressing perforin and granzyme B were observed in sarcoidosis compared to healthy controls. Blood CTLs from non-LS patients had significantly higher expression of perforin, granzyme B and granulysin compared to matched BAL, while LS patients maintained lower levels of effector molecules in both compartments. Mitogen-stimulated peripheral lymphocytes from sarcoidosis patients, particularly from the non-LS group, showed a higher target cell lysis compared to controls., Conclusion: These results demonstrated enhanced peripheral CD8 + CTL responses in sarcoidosis, especially in non-LS patients who have an increased risk of chronic disease. Further comprehensive clinical studies are warranted to increase our understanding of CD8 + CTL responses in sarcoidosis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Macrophages play a central role in the pathogenesis of inflammatory and fibrotic lung diseases. However, alveolar macrophages (AM) are poorly available in humans to perform in vitro studies due to a limited access to broncho-alveolar lavage (BAL). In this study, to identify the best alternative in vitro model for human AM, we compared the phenotype of AM obtained from BAL of patients suffering from three lung diseases (lung cancers, sarcoidosis and Systemic Sclerosis (SSc)-associated interstitial lung disease) to human blood monocyte-derived macrophages (MDMs) differentiated with M-CSF or GM-CSF. The expression of eight membrane markers was evaluated by flow cytometry. Globally, AM phenotype was closer to GM-CSF MDMs. However, the expression levels of CD163, CD169, CD204, CD64 and CD36 were significantly higher in SSc-ILD than in lung cancers. Considering the expression of CD204 and CD36, the phenotype of SSc-AM was closer to MDMs, from healthy donors or SSc patients, differentiated by M-CSF rather than GM-CSF. The comparative secretion of IL-6 by SSc-MDMs and SSc-AM is concordant with these phenotypic considerations. Altogether, these results support the M-CSF MDM model as a relevant in vitro alternative to simulate AM in fibrotic disorders such as SSc., Competing Interests: The authors declare no conflict of interest.

As new immunomodulatory therapies continue to be licensed for use in Multiple Sclerosis, it is important to remain vigilant for new, unexpected associations relating to these medications. We highlight this by reporting on a case of a 45-year-old man who developed systemic, non-specific symptoms following long term use of daclizumab and was subsequently diagnosed with sarcoidosis. We go on to briefly discuss the action of daclizumab, in particular the effect it has on CD56 bright natural killer cells, a cell type that has been investigated in relation to sarcoidosis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Sarcoidosis, a multisystem granulomatous disorder, has historically been classified as Th1-driven disease. However, increasing data demonstrate a key role of Th17-cell plasticity in granuloma formation and maintenance. In Löfgren's syndrome (LS), an acute and distinct phenotype of sarcoidosis with a favorable outcome, differences in Th17-lineage cell subsets, cytokine expression and T-cell suppressive mechanisms may account for differences in clinical presentation as well as prognosis compared to non-LS sarcoidosis. In contrast with LS, up to 20% of non-LS sarcoidosis patients may progress to irreversible pulmonary fibrosis. In non-LS sarcoidosis patients, IFN-γ-producing Th17.1-cells appear to be more pathogenic and possibly linked to disease progression, while a broader range of cytokines is found in bronchoalveolar lavage fluid (BALF) in LS patients. Differences in Cytotoxic T-lymphocyte antigen 4 (CTLA-4) expression on Th17-cells and regulatory T-cells (Treg) could contribute to Th17-cell pathogenicity and consequently to either disease resolution or ongoing inflammation in sarcoidosis. Furthermore, several genes and SNPs are associated with disease susceptibility and outcome in sarcoidosis, the majority of which are involved in antigen presentation, T-cell activation or regulation of T-cell survival. Novel insights into the role of Th17-cells in the pathogenesis of both LS and non-LS sarcoidosis will unravel pathogenic and benign Th17-lineage cell function and drivers of Th17-cell plasticity. This will also help identify new treatment strategies for LS and non-LS sarcoidosis patients by altering Th17-cell activation, suppress conversion into more pathogenic subtypes, or influence cytokine signaling towards a beneficial signature of Th17-lineage cells. In this review, we summarize new insights into Th17-cell plasticity in the complex pathogenesis of sarcoidosis and connect these cells to the different disease phenotypes, discuss the role of genetic susceptibility and autoimmunity and focus on possible treatment strategies., (Copyright © 2017. Published by Elsevier Ltd.)

Background: Sarcoidosis is a granulomatous disease of unknown etiology. Macrophages play a key role in granuloma formation with the T cells, having a significant impact on macrophage polarization (M1 and M2) and the cellular composition of the granuloma. This study evaluates macrophage polarization in granulomas in pulmonary sarcoidosis., Materials and Methods: Tissue specimens from the Department of Pathology biobank at the Masih Daneshvari Hospital were obtained. Paraffin sections from 10 sarcoidosis patients were compared with those from 12 cases of tuberculosis using immunohistochemical staining. These sections consisted of mediastinal lymph nodes and transbronchial lung biopsy (TBLB) for sarcoidosis patients versus pleural tissue, neck, axillary lymph nodes and TBLB for tuberculosis patients. The sections were stained for T-cells (CD4+, CD8+) and mature B lymphocytes (CD22+). CD14+ and CD68+ staining was used as a marker of M1 macrophages and CD163+ as a marker for M2 macrophages., Results: Immunohistochemical staining revealed a 4/1 ratio of CD4+/CD8+ T-cells in sarcoidosis granuloma sections and a 3/1 ratio in tuberculosis sections. There was no significance difference in single CD4+, CD8+, CD22+, CD14+ and CD68+ staining between sarcoidosis and tuberculosis sections. CD163 expression was significantly increased in sarcoidosis sections compared with those from tuberculosis subjects., Conclusion: Enhanced CD163+ staining indicates a shift towards M2 macrophage subsets in granulomas from sarcoidosis patients. Further research is required to determine the functional role of M2 macrophages in the immunopathogenesis of sarcoidosis., (Copyright © 2017 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

Many aspects of pathogenic granuloma formation are poorly understood, requiring new relevant laboratory models that represent the complexity (genetics and diversity) of human disease. To address this need, we developed an in vitro model of granuloma formation using human peripheral blood mononuclear cells (PBMCs) derived from patients with active sarcoidosis, latent tuberculosis (TB) infection (LTBI), or normal healthy control subjects. PBMCs were incubated for 7 days with uncoated polystyrene beads or beads coated with purified protein derivative (PPD) or human serum albumin. In response to PPD-coated beads, PBMCs from donors with sarcoidosis and LTBI formed robust multicellular aggregates resembling granulomas, displaying a typical T-helper cell type 1 immune response, as assessed by cytokine analyses. In contrast, minimal PBMC aggregation occurred when control PBMCs were incubated with PPD-coated beads, whereas the response to uncoated beads was negligible in all groups. Sarcoidosis PBMCs responded to human serum albumin-coated beads with modest cellular aggregation and inflammatory cytokine release. Whereas the granuloma-like aggregates formed in response to PPD-coated beads were similar for sarcoidosis and LTBI, molecular profiles differed significantly. mRNA expression patterns revealed distinct pathways engaged in early granuloma formation in sarcoidosis and LTBI, and they resemble molecular patterns reported in diseased human tissues. This novel in vitro human granuloma model is proposed as a tool to investigate mechanisms of early granuloma formation and for preclinical drug discovery research of human granulomatous disorders. Clinical trial registered with www.clinicaltrials.gov (NCT01857401).

Dendritic cells (DCs) are highly specialized immune cells that capture antigens and then migrate to lymphoid tissue and present antigen to T cells. This critical function of DCs is well defined, and recent studies further demonstrate that DCs are also key regulators of several innate immune responses. Studies focused on the roles of DCs in the pathogenesis of common lung diseases, such as asthma, infection, and cancer, have traditionally driven our mechanistic understanding of pulmonary DC biology. The emerging development of novel DC reagents, techniques, and genetically modified animal models has provided abundant data revealing distinct populations of DCs in the lung, and allow us to examine mechanisms of DC development, migration, and function in pulmonary disease with unprecedented detail. This enhanced understanding of DCs permits the examination of the potential role of DCs in diseases with known or suspected immunological underpinnings. Recent advances in the study of rare lung diseases, including pulmonary Langerhans cell histiocytosis, sarcoidosis, hypersensitivity pneumonitis, and pulmonary fibrosis, reveal expanding potential pathogenic roles for DCs. Here, we provide a review of DC development, trafficking, and effector functions in the lung, and discuss how alterations in these DC pathways contribute to the pathogenesis of rare lung diseases.

Sarcoidosis is a granulomatous disease that primarily affects the lungs and is characterized by an accumulation of CD4 + T cells in the bronchoalveolar lavage (BAL). Previous work has indicated that HLA-DRB1*03:01 + (DR3 + ) patients diagnosed with the acute form of the disease, Löfgren's syndrome (LS), have an accumulation of CD4 + T cells bearing TCRs using TRAV12-1 (formerly AV2S3). However, the importance of these α-chains in disease pathogenesis and the paired TCRβ-chain remains unknown. This study aimed to identify expanded αβTCR pairs expressed on CD4 + T cells derived from the BAL of DR3 + LS patients. Using a deep-sequencing approach, we determined TCRα- and TCRβ-chain usage, as well as αβTCR pairs expressed on BAL CD4 + T cells from LS patients. TRAV12-1 and TRBV2 (formerly BV22) were the most expanded V region gene segments in DR3 + LS patients relative to control subjects, and TRAV12-1 and TRBV2 CDR3 motifs were shared among multiple DR3 + LS patients. When assessing αβTCR pairing, TRAV12-1 preferentially paired with TRBV2, and these TRAV12-1/TRBV2 TCRs displayed CDR3 homology. These findings suggest that public CD4 + TCR repertoires exist among LS patients and that these T cells are recognizing the putative sarcoidosis-associated Ag(s) in the context of DR3., (Copyright © 2017 by The American Association of Immunologists, Inc.)

Background: Sarcoidosis is a systemic inflammatory disorder characterized by granulomas. Not enough evidences correlate the derangement of CD4+ T subsets, which have an impact on the therapeutic effects of corticosteroids, with the radiographical staging of sarcoidosis. Here we show the disturbance of CD4+ T subsets in newly diagnosed stage II pulmonary sarcoidosis, which is the most common stage in which corticosteroids treatment is used., Materials and Methods: 39 newly diagnosed and treatment-naïve patients and 9 subjects after corticosteroids treatment were included. CD4+ CD45RA+/ CD45RO+ cells, CCR4+ CCR6+ cells, and T regulatory cells (Tregs) were tested by Flow Cytometry Analysis. Th1/Th2, Tregs/Th17 related cytokines and mRNAs, SAA and CCL20 were also measured. The activation of PI3K/PTEN/Akt signaling pathway was detected., Results: Percentages of CD4+CD45RO+ memory T cells and Tregs, serum levels of IL-17A, TGF-β1, IL-6, IFN-γ, IL-10, SAA and CCL20, copies of T-bet, FoxP3, IL-17 and RORc in the periphery were elevated in newly diagnosed stage II pulmonary sarcoidosis patients. Additionally, PI3K/Akt signaling pathway was activated in bronchoalveolar lavage fluid cells., Conclusions: Disturbance of T memory cells, Th1/Th2, and Tregs/Th17 cells, and activation of PI3K/Akt signaling were seen in newly diagnosed stage II pulmonary sarcoidosis, which can be partly ameliorated by corticosteroids treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Objective: To compare the inflammatory factors and immune functions of patients with lung cancer and pulmonary ground-glass attenuation., Patients and Methods: A total of 108 patients with pulmonary sarcoidosis treated in our hospital were selected and randomly divided into lung cancer group (Group A, n=32), diffuse ground-glass nodule group (Group B, n=35) and solitary ground-glass nodule group (Group C, n=41) according to the diagnosis results. Levels of inflammatory factors, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukin-10 (IL-10), in serum were detected via enzyme-linked immunosorbent assay (ELISA); the T-lymphocyte subset levels (CD3+, CD4+, CD8+ and CD4+/CD8+) in the immune system of patients in the three groups were detected using the flow cytometer; the levels of immunoglobulins, immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM), were detected via immunoturbidimetric assay., Results: There were no significant differences in the levels of TNF-α, IL-1β, IL-6 and IL-10 in patients between Group A and Group B (p>0.05), but the levels in Group A and Group B were significantly higher than those in Group C (p<0.05). There were no significant differences in the levels of CD3+, CD4+, CD8+ and CD4+/CD8+ in patients between Group A and Group B (p>0.05), but the levels in Group A and Group B were significantly lower than those in Group C (p<0.05). There were no significant differences in the levels of IgG, IgA and IgM in patients between Group A and Group B (p>0.05), but the levels in Group A and Group B were significantly lower than those in Group C (p<0.05)., Conclusions: There are lower inflammation and immune functions in patients with lung cancer and pulmonary ground-glass attenuation. Compared with those in patients with lung cancer and diffuse ground-glass nodules, the inflammatory degree in patients with solitary ground-glass nodules is lower and the immune functions are better. Detecting the inflammatory factors and immune functions of patients can also be used as a differential diagnosis means of lung cancer.

Background: Vitamin D insufficiency is associated with autoimmune and chronic inflammatory diseases such as tuberculosis and sarcoidosis., Objectives: To evaluate the vitamin D-dependent mechanisms of immunity and autoimmunity in different forms of pulmonary tuberculosis and sarcoidosis., Methods: We measured the serum levels of 25(OH)D and 1,25(OH)2D, individual autoimmune profiles, plasma concentrations of cathelicidin, several hormones, and production of nine cytokines in patients with short- and long-duration tuberculosis and sarcoidosis., Results: The level of 25(OH)D was significantly decreased in all patients. Concentration of 1,25(OH)2D was elevated only in sarcoidosis, prolactin content was augmented only in tuberculosis. We saw no expected increase of cathelicidin levels in tuberculosis and sarcoidosis. The individual mean immune reactivity levels of autoantibodies to 24 antigens were significantly lower in tuberculosis and sarcoidosis patients compared to healthy controls. Pronounced deviations from individual mean immune reactivity levels were found for several autoantigens in all patients. The induced production of interferon gamma-γ, interleukin (IL) 2, 17, and 8 by peripheral blood mononuclear cells was significantly increased in patients of both tuberculosis groups, but spontaneous production of tumor necrosis factor-α, IL-2, and IL-6 was lower in the tuberculosis patients than in healthy controls. We registered marked differences in the groups of tuberculosis patients., Conclusions: We demonstrated the role of vitamin D deficiency in poor cathelicidin response in  tuberculosis and sarcoidosis. Both diseases are accompanied by significant changes in the autoimmune profile, probably related to the status of vitamin D and cytokine regulation.

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Background and Objective: Acute eosinophilic pneumonia (AEP) is characterized by a massive pulmonary infiltration of eosinophils. Mechanisms regulating the selective accumulation of eosinophils in AEP have not been fully established. The objective of this study was to evaluate the mechanisms of eosinophil accumulation in alveolar spaces through examination of bronchoalveolar lavage fluid (BALF) from AEP patients (AEP-BALF)., Methods: Eosinophils were isolated from the blood of healthy subjects and were placed on a human pulmonary microvascular endothelial cell monolayer cultured on Transwell filters (Coster, Cambridge, MA, USA). A saline control solution or BALF from patients with AEP, sarcoidosis or hypersensitivity pneumonitis was applied to the lower compartment, and the transendothelial migration of the eosinophils was evaluated. The concentrations of cytokines and chemokines in BALF were also measured., Results: Transmigration of eosinophils across endothelial cells was only induced by the AEP-BALF. This transmigration was blocked by anti-β 2 integrin mAb. The concentrations of eotaxin-2 and monocyte chemotactic protein (MCP)-4, which are CC chemokine receptor (CCR) 3 ligands, were elevated in the AEP-BALF, and anti-CCR3 mAb or anti-MCP-4 mAb inhibited the AEP-BALF-induced transmigration of eosinophils. Furthermore, the concentration of leukotriene (LT) B 4 was increased in the AEP-BALF, and an LTB 4 receptor antagonist partially suppressed the AEP-BALF-induced transmigration of eosinophils., Conclusion: These findings suggest that CCR3 ligands including eotaxin-2 and MCP-4, and LTB 4 play a role in the accumulation of eosinophils in AEP., (© 2017 Asian Pacific Society of Respirology.)

Sarcoidosis, a chronic inflammatory disorder, results from increased immune responses. Its development can be triggered in patients under immunotherapy, as activation of the immune system in these patients is desired. Since 1997, 249 patients with metastasized cutaneous melanoma (stage III and IV, AJCC 2009) have been treated with dendritic cell (DC)-based vaccines at our hospital. Three out of these patients were diagnosed with sarcoidosis after or during long-term DC vaccination therapy (1.20%). Metastatic disease was initially suspected based on the radiographic manifestation of lung masses or bilateral hilar lymphadenopathy. Histological assessment, however, revealed the appropriate diagnosis. Interestingly, all three patients are long-term responders and have remained free of metastatic or progressive disease for over a period of at least 4 years. In summary, sarcoidosis can occur in patients with cancer who have benefited from DC-based therapeutic vaccination and thus, its development, even with substantial delay, may be associated with successful anticancer immunotherapy., (Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Investigation of the Th1 immune response in sarcoidosis CD4 + T cells has revealed reduced proliferative capacity and cytokine expression upon TCR stimulation. In other disease models, such cellular dysfunction has been associated with a step-wise, progressive loss of T cell function that results from chronic antigenic stimulation. T cell exhaustion is defined by decreased cytokine production upon TCR activation, decreased proliferation, increased expression of inhibitory cell surface receptors, and increased susceptibility to apoptosis. We characterized sarcoidosis CD4 + T cell immune function in systemic and local environments among subjects undergoing disease progression compared to those experiencing disease resolution. Spontaneous and TCR-stimulated Th1 cytokine expression and proliferation assays were performed in 53 sarcoidosis subjects and 30 healthy controls. PD-1 expression and apoptosis were assessed by flow cytometry. Compared to healthy controls, sarcoidosis CD4 + T cells demonstrated reductions in Th1 cytokine expression, proliferative capacity ( p < 0.05), enhanced apoptosis ( p < 0.01), and increased PD-1 expression ( p < 0.001). BAL-derived CD4 + T cells also demonstrated multiple facets of T cell exhaustion ( p < 0.05). Reversal of CD4 + T cell exhaustion was observed in subjects undergoing spontaneous resolution ( p < 0.05). Sarcoidosis CD4 + T cells exhibit loss of cellular function during progressive disease that follows the archetype of T cell exhaustion.

Background: Airway abnormalities and lung tissue citrullination are found in both rheumatoid arthritis (RA) patients and individuals at-risk for disease development. This suggests the possibility that the lung could be a site of autoimmunity generation in RA, perhaps in response to microbiota changes. We therefore sought to test whether the RA lung microbiome contains distinct taxonomic features associated with local and/or systemic autoimmunity., Methods: 16S rRNA gene high-throughput sequencing was utilized to compare the bacterial community composition of bronchoalveolar lavage fluid (BAL) in patients with early, disease-modifying anti-rheumatic drugs (DMARD)-naïve RA, patients with lung sarcoidosis, and healthy control subjects. Samples were further assessed for the presence and levels of anti-citrullinated peptide antibodies (including fine specificities) in both BAL and serum., Results: The BAL microbiota of RA patients was significantly less diverse and abundant when compared to healthy controls, but similar to sarcoidosis patients. This distal airway dysbiosis was attributed to the reduced presence of several genus (i.e., Actynomyces and Burkhordelia) as well as reported periodontopathic taxa, including Treponema, Prevotella, and Porphyromonas. While multiple clades correlated with local and systemic levels of autoantibodies, the genus Pseudonocardia and various related OTUs were the only taxa overrepresented in RA BAL and correlated with higher disease activity and erosions., Conclusions: Distal airway dysbiosis is present in untreated early RA and similar to that detected in sarcoidosis lung inflammation. This community perturbation, which correlates with local and systemic autoimmune/inflammatory changes, may potentially drive initiation of RA in a proportion of cases.

Background: The galaxy sign is an irregularly marginated pulmonary nodule formed by a confluence of multiple small nodules, and it is a diagnostic radiological finding for pulmonary sarcoidosis. However, the clinical significance of the galaxy sign for sarcoidosis has been poorly investigated., Objective: This study aimed to investigate the clinical significance and detailed radiological features of the galaxy sign in patients with pulmonary sarcoidosis., Methods: We retrospectively reviewed 87 patients with biopsy-proven sarcoidosis and 108 patients with pulmonary tuberculosis. Galaxy sign incidence was assessed on thoracic high-resolution computed tomography (HRCT) images from each group. Correlations of galaxy sign with clinical characteristics and disease outcomes were evaluated for patients with sarcoidosis., Results: HRCT findings were available for 65 of 87 patients with pulmonary sarcoidosis and all 108 patients with pulmonary tuberculosis. Galaxy sign incidence was significantly higher in patients with pulmonary sarcoidosis (n=15, 23.1%) than in those with pulmonary tuberculosis (n=2, 1.9%, p<0.001). Among the 65 patients with pulmonary sarcoidosis, those with galaxy signs (n=15) were significantly younger (median: 32 years, interquartile range [IQR] 28-38 years) than those without (n=50) (median: 62 years, IQR 37.7-73 years). The CD4/CD8 ratio in bronchoalveolar lavage fluid (BALF) was also significantly lower in the former group (median: 2.6, IQR 2.0-3.9 vs. median 5.8, IQR 3.7-8.6, p<0.001)., Conclusion: Galaxy signs are associated with younger age and low BALF CD4/CD8 ratio but not disease severity.