Increased IL-17A expression in granulomas and in circulating memory T cells in sarcoidosis

Increased proportions of circulating PD-1+ CD4+ memory T cells and PD-1+ regulatory T cells associate with good response to prednisone in pulmonary sarcoidosis

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.

Advance in pathogenesis of sarcoidosis: Triggers and progression

Sarcoidosis, a multisystemic immune disease, significantly impacts patients' quality of life. The complexity and diversity of its pathogenesis, coupled with limited comprehensive research, had hampered both diagnosis and treatment, resulting in an unsatisfactory prognosis for many patients. In recent years, the research had made surprising progress in the triggers of sarcoidosis (genetic inheritance, infection and environmental factors) and the abnormal regulations on immunity during the formation of granuloma. This review consolidated the latest findings on sarcoidosis research, providing a systematic exploration of advanced studies on triggers, immune-related regulatory mechanisms, and clinical applications. By synthesizing previous discoveries, we aimed to offer valuable insights for future research directions and the development of clinical diagnosis and treatment strategies.

Differential Upregulation of Th1/Th17-Associated Proteins and PD-L1 in Granulomatous Mycosis Fungoides

Granulomatous Mycosis Fungoides (GMF) is a rare form of mycosis fungoides (MF) characterized by a granulomatous infiltrate associated with the neoplastic lymphoid population and is considered to have a worse prognosis compared with regular MF. The upregulation of the T helper (Th) axis, especially Th17, plays an important role in the pathogenesis of several inflammatory/infectious granulomatous cutaneous diseases, but its role in GMF is still not elucidated to date. In this study, we evaluated the immunohistochemical expression of Th1 (Tbet), Th2 (GATA-3), Th17 (RORγT), T regulatory (Foxp3), and immune checkpoint (IC) (PD-1 and PD-L1) markers in a cohort of patients with GMF and MF with large cell transformation (MFLCT). Skin biopsies from 49 patients (28 GMF and 21 MFLCT) were studied. Patients with GMF were associated with early clinical stage (p = 0.036) and lower levels of lactate dehydrogenase (p = 0.042). An increased percentage of cells positive for Tbet (p = 0.017), RORγT (p = 0.001), and PD-L1 (p = 0.011) was also observed among the GMF specimens, while a stronger PD-1 intensity was detected in cases of MFLCT. In this cohort, LCT, RORγT < 10%, Foxp3 < 10%, age, and advanced stage were associated with worse overall survival (OS) in univariate analysis. GMF demonstrated Th1 (cellular response) and Th17 (autoimmunity) phenotype, seen in early MF and granulomatous processes, respectively, which may be related to the histopathological appearance and biological behavior of GMF. Further studies involving larger series of cases and more sensitive techniques are warranted.

High expression of interleukin-17A in cutaneous sarcoidosis

Increasing evidence of Th17 pathways is implicated in sarcoidosis granulomatous inflammation and maintenance. Our study evaluated the presence of IL-17A, a downstream proinflammatory cytokine, in cutaneous sarcoidosis biopsies. We found that all 26 biopsy samples had increased expression of IL-17A, predominantly located in macrophages within granulomas, in the cytoplasm of multinucleated histiocytes surrounding the granulomas and within lymphocytic infiltrates surrounding the inflammation.

Dexamethasone alleviates pulmonary sarcoidosis by regulating the TGF-β/Smad3 signaling to promote Th17/Treg cell rebalance

Pulmonary sarcoidosis is an immune-mediated disorder closely related to Th17/Treg cell imbalance. Dexamethasone has been shown to regulate inflammation and immune responses in sarcoidosis patients. However, the underlying mechanisms of dexamethasone regulating Th17/Treg balance in sarcoidosis remain elusive. Herein, we elucidated the function role of TGF-β/Smad3 signaling in pulmonary sarcoidosis development and explored the underlying mechanism of dexamethasone in treating pulmonary sarcoidosis. We found that the TGF-β/Smad3 pathway was inactivated in pulmonary sarcoidosis patients. Propionibacterium acnes (PA) induced mouse model was generated to investigate the function of TGF-β/Smad3 signaling in vivo. Data indicated that IL17A inhibition with neutralizing antibody and activation of TGF-β/Smad3 signaling with SRI-011381 alleviated granuloma formation in the sarcoidosis mouse model. Moreover, we revealed that the Th17/Treg cell ratio was increased with PA treatment in mouse bronchoalveolar lavage fluid (BALF) and peripheral blood. The concentration of cytokines produced by Th17 cells (IL-17A, IL-23) was up-regulated in the BALF of PA-treated mice, while those produced by Tregs (IL-10, TGF-β1) presented significant reduction. The treatment of IL-17A neutralizing antibody or SRI-011381 was demonstrated to rescue the PA-induced changes in the concentration of IL-17A, IL-23, IL-10, and TGF-β1. Additionally, we demonstrated that dexamethasone treatment activated the TGF-β/Smad3 signaling in the lung tissues of pulmonary sarcoidosis mice. Dexamethasone was also revealed to promote the rebalancing of the Th17/Treg ratio and attenuated the granuloma formation in pulmonary sarcoidosis. In conclusion, dexamethasone activates the TGF-β/Smad3 signaling and induces Th17/Treg rebalance, alleviating pulmonary sarcoidosis, which suggests the potential of dexamethasone in treating pulmonary sarcoidosis.

Increased circulating interleukin-23 level in patients with sarcoidosis

BACKGROUND

Sarcoidosis is a Th1-mediated chronic inflammatory disease characterized by non-caseating granulomas. Its pathogenesis is not yet clear, but the possible role of various proinflammatory cytokines is being discussed.

AIM

This study aims to determine serum cytokine (IL-6, IL-12, IL-17, and IL-23) levels in patients with sarcoidosis, and to determine a possible correlation with clinical and laboratory findings of the disease.

MATERIAL AND METHOD

Forty-four biopsy-proven sarcoidosis patients followed up at a single centre and 41 healthy volunteers were included in the study. Demographic, clinical, laboratory, and radiological data of all patients were recorded. Serum samples from the patients and the control group were taken and IL-6, IL-12, IL-17, IL-23 were measured by ELISA method.

RESULTS

Of the 44 sarcoidosis patients, 13(29.5%) were male and 31(70.5%) were female. Average patient age was 47.4 years, mean disease duration was 3.2 years. Twenty-one (47.7%) patients had erythema nodosum, three (6.8%) had uveitis, 40(90.9%) had arthralgia, 23(52.3%) had ankle arthritis, 15(34.1%) had enthesitis. Laboratory evaluation showed increased serum ACE levels in 24(54.5%) patients, increased serum calcium levels in 11 (25%) patients, increased serum D3 levels in 5(11.4%) patients, increased ESR and CRP levels in 22(50%) and 23(52.3%) patients, respectively. Compared with the control group higher serum IL-23 levels were found in the patients with sarcoidosis (p=.01). Serum IL-23 was associated with ankle arthritis (p=.02). Serum IL-6, IL-12, and IL-17 levels were similar in the sarcoidosis patients and the control group (p=.128, p=.212, p=.521 respectively).

CONCLUSION

In our study, we found increased serum IL-23 in patients with sarcoidosis, while serum IL-6, IL-12, and IL-17 were detected as normal. Although our results are somewhat contradictory to other studies in the literature, the question should still be whether sarcoidosis is a Th1/Th17 disease. Multicentre studies are needed in this regard.

Genetic predisposition to sarcoidosis

Sarcoidosis is a complex systemic disease with clinical heterogeneity based on varying phenotypes and natural history. The detailed etiology of sarcoidosis remains unknown, but genetic predisposition as well as environmental exposures play a significant role in disease pathogenesis. We performed a comprehensive review of germline genetic (DNA) and transcriptomic (RNA) studies of sarcoidosis, including both previous studies and more recent findings. In this review, we provide an assessment of the following: genetic variants in sarcoidosis susceptibility and phenotypes, ancestry- and sex-specific genetic variants in sarcoidosis, shared genetic architecture between sarcoidosis and other diseases, and gene-environment interactions in sarcoidosis. We also highlight the unmet needs in sarcoidosis genetic studies, including the pressing requirement to include diverse populations and have consistent definitions of phenotypes in the sarcoidosis research community to help advance the application of genetic predisposition to sarcoidosis disease risk and manifestations.

Circulating T cells in sarcoidosis have an aberrantly activated phenotype that correlates with disease outcome

RATIONALE

Disease course in sarcoidosis is highly variable. Bronchoalveolar lavage fluid and mediastinal lymph nodes show accumulation of activated T cells with a T-helper (Th)17.1 signature, which correlates with non-resolving sarcoidosis. We hypothesize that the peripheral blood (PB) T cell phenotype may correlate with outcome.

OBJECTIVES

To compare frequencies, phenotypes and function of circulating T cell populations in sarcoidosis patients with healthy controls (HCs) and correlate these parameters with outcome.

METHODS

We used multi-color flow cytometry to quantify activation marker expression on PB T cell subsets in treatment-naïve patients and HCs. The disease course was determined after 2-year follow-up. Cytokine production was measured after T cell stimulation in vitro.

MEASUREMENTS AND MAIN RESULTS

We observed significant differences between patients and HCs in several T cell populations, including CD8+ and CD4+ T cells, Th1/Th17 subsets, CD4+ T memory stem cells, regulatory T cells (Tregs) and γδ T cells. Decreased frequencies of CD4+ T cells and increased frequencies of Tregs and CD8+ γδ T cells correlated with worse outcome. Naïve CD4+ T cells displayed an activated phenotype with increased CD25 expression in patients with active chronic disease at 2-year follow-up. A distinctive Treg phenotype with increased expression of CD25, CTLA4, CD69, PD-1 and CD95 correlated with chronic sarcoidosis. Upon stimulation, both naïve and memory T cells displayed a different cytokine profile in sarcoidosis compared to HCs.

CONCLUSIONS

Circulating T cell subpopulations of sarcoidosis patients display phenotypic abnormalities that correlate with disease outcome, supporting a critical role of aberrant T cell activation in sarcoidosis pathogenesis.

T-cell signature cytokines distinguish pulmonary sarcoidosis from pulmonary tuberculosis

Sarcoidosis is a systemic inflammatory disorder characterized by tissue infiltration due to mononuclear phagocytes and lymphocytes and associated noncaseating granuloma formation. Pulmonary sarcoidosis (PS) shares a number of clinical, radiological, and histopathological characteristics with that of pulmonary tuberculosis (PTB). Due to this, clinicians face issues in differentiating between PS and PTB in a substantial number of cases. There is a lack of any specific biomarker that can diagnose PS distinctively from PTB. We compared T-cell-based signature cytokines in patients with PS and PTB. In this study, we proposed a serum biomarker panel consisting of cytokines from cells: T helper (Th) 1 [interferon-gamma (IFN-γ); tumor necrosis factor-alpha (TNF-α)], Th9 [interleukin (IL)-9], Th17 [IL-17], and T regulatory (Treg) [IL-10; transforming growth factor-beta (TGF-β)]. We performed the principal component analysis that demonstrated that our serum cytokine panel has a significant predictive ability to differentiate PS from PTB. Our results could aid clinicians to improve the diagnostic workflow for patients with PS in TB endemic settings where the diagnosis between PS and PTB is often ambiguous.

Imbalanced distribution of regulatory T cells and Th17.1 cells in the peripheral blood and BALF of sarcoidosis patients: relationship to disease activity and the fibrotic radiographic phenotype

Rationale

Sarcoidosis is a granulomatous interstitial lung disease involving a complex interplay among different cluster of differentiation 4 (CD4⁺) thymus cell (T-cell) subsets. Originally described as a type 1 T-helper (Th1) inflammatory disease, recent evidence suggests that both effector and regulatory T-cell subgroups play a critical role in sarcoidosis, but this remains controversial.

Objectives

We aimed to investigate the distribution of CD4⁺ T-cell subpopulations in sarcoidosis patients and its potential associations with clinical disease activity and a radiographic fibrotic phenotype.

Methods

We measured the frequencies of regulatory T cells (Tregs), Th1, Th17, and Th17.1 cells in the peripheral blood and/or bronchoalveolar lavage fluid (BALF) of 62 sarcoidosis patients, 66 idiopathic pulmonary fibrosis (IPF) patients, and 41 healthy volunteers using flow cytometry. We also measured the changes in these T-cell subpopulations in the blood at the follow-up visits of 11 sarcoidosis patients.

Measurements and results

An increased percentage of Tregs was observed in the peripheral blood of sarcoidosis patients, with a positive association to disease activity and a fibrotic radiographic phenotype. We found a higher frequency of Tregs, a lower proportion of Th17.1 cells, and a lower ratio of Th17.1 cells to total Tregs in the peripheral blood of both active and fibrotic sarcoidosis patients, compared with IPF patients or healthy donors. In contrast, a lower frequency of Tregs and a higher proportion of Th17.1 cells was found in the BALF of sarcoidosis patients than in that of IPF patients. There was an imbalance of Tregs and Th17.1 cells between the peripheral blood and BALF in sarcoidosis patients. Following immunoregulatory therapy, the proportion of circulating Tregs in sarcoidosis patients decreased.

Conclusion

A higher proportion of Tregs in the peripheral blood of sarcoidosis patients was related to disease activity, fibrotic phenotype, and the need for immunoregulatory therapy. The imbalanced distribution of Tregs and Th17.1 cells in patients' peripheral blood and BALF suggests that the lung microenvironment has an effect on the immunological pathogenesis of sarcoidosis. Therefore, further studies on the functional analysis of Tregs and Th17.1 cells in sarcoidosis patients are warranted.

Immune mechanisms in fibrotic pulmonary sarcoidosis

Sarcoidosis is an immune-mediated disorder. Its immunopathology has been steadily mapped out over the past few decades. Despite this, the underpinning mechanisms for progressive fibrotic sarcoidosis is an almost uncharted area. Consequently, there has been little change in the clinical management of fibrotic sarcoidosis over the decades and an unfocused search for new therapeutics. In this review, we provide a comprehensive examination of the relevant immune findings in fibrotic and/or progressive pulmonary sarcoidosis and propose a unifying mechanism for the pathobiology of fibrosis in sarcoidosis.

Sarcoid-like Granulomatosis Associated with Immune Checkpoint Inhibitors in Melanoma

We aimed to review the clinical and biological presentation of granulomatosis associated with immune-checkpoint inhibitors (ICI) in patients with melanoma and to explore its association with classical sarcoidosis as well as with cancer response to ICI. To this end, a retrospective study on 18 melanoma patients with histologically proven ICI-induced granulomatosis over a 12-year period in a single center, as well as on 67 similar cases reported in the literature, was conducted. Results indicate ICI-induced granulomatosis is an early side effect (median time to onset: 2 months). Its clinical presentation, with predominant (90%) thoracic involvement, histopathological appearance and supposed underlying biology (involving the mTOR pathway in immune cells, Th17 polarization and TReg dysfunction) are indistinguishable from those of sarcoidosis. Moreover, it appears to be associated with ICI benefit (>65% objective response rate). Evolution is generally favorable, and symptomatic steroid treatment and/or ICI discontinuation are rarely necessary. ICI-associated granulomatosis is critical to explore for several reasons. Practically, it is essential to differentiate it from cancer progression. Secondly, this “experimental” sarcoidosis brings new elements that may help to address sarcoidosis origin and pathophysiology. Its association with ICI efficacy must be confirmed on a larger scale but could have significant impacts on patient management and biomarker definition.

The Evolving Landscape of Cutaneous Sarcoidosis: Pathogenic Insight, Clinical Challenges, and New Frontiers in Therapy

Sarcoidosis is a multisystem disorder of unknown etiology characterized by accumulation of granulomas in affected tissue. Cutaneous manifestations are among the most common extrapulmonary manifestations in sarcoidosis and can lead to disfiguring disease requiring chronic therapy. In many patients, skin disease may be the first recognized manifestation of sarcoidosis, necessitating a thorough evaluation for systemic involvement. Although the precise etiology of sarcoidosis and the pathogenic mechanisms leading to granuloma formation, persistence, or resolution remain unclear, recent research has led to significant advances in our understanding of this disease. This article reviews recent advances in epidemiology, sarcoidosis clinical assessment with a focus on the dermatologist's role, disease pathogenesis, and new therapies in use and under investigation for cutaneous and systemic sarcoidosis.

Single-Cell Transcriptomics Reveals Peripheral Immune Responses in Anti-Synthetase Syndrome-Associated Interstitial Lung Disease

OBJECTIVE

Interstitial lung diseases (ILDs) secondary to anti-synthetase syndrome (ASS) greatly influence the prognoses of patients with ASS. Here we aimed to investigate the peripheral immune responses to understand the pathogenesis of this condition.

METHODS

We performed single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells (PBMCs) from 5 patients with ASS-ILD and 3 healthy donors (HDs). Flow cytometry of PBMCs was performed to replenish the results of scRNA-seq.

RESULTS

We used scRNA-seq to depict a high-resolution visualization of cellular landscape in PBMCs from patients with ASS-ILD. Patients showed upregulated interferon responses among NK cells, monocytes, T cells, and B cells. And the ratio of effector memory CD8 T cells to naïve CD8 T cells was significantly higher in patients than that in HDs. Additionally, Th1, Th2, and Th17 cell differentiation signaling pathways were enriched in T cells. Flow cytometry analyses showed increased proportions of Th17 cells and Th2 cells, and decreased proportion of Th1 cells in patients with ASS-ILD when compared with HDs, evaluated by the expression patterns of chemokine receptors.

CONCLUSIONS

The scRNA-seq data analyses reveal that ASS-ILD is characterized by upregulated interferon responses, altered CD8 T cell homeostasis, and involvement of differentiation signaling pathways of CD4 T cells. The flow cytometry analyses show that the proportions of Th17 cells and Th2 cells are increased and the proportion of Th1 cells is decreased in patients with ASS-ILD. These findings may provide foundations of novel therapeutic targets for patients with this condition.

Chronic Inflammation as the Underlying Mechanism of the Development of Lung Diseases in Psoriasis: A Systematic Review

Psoriasis is a systemic inflammatory disease caused by dysfunctional interactions between the innate and adaptive immune responses. The systemic inflammation in psoriasis may be associated with the development of comorbidities, including lung diseases. In this review, we aimed to provide a summary of the evidence regarding the prevalence of lung diseases in patients with psoriasis and the potential underlying mechanisms. Twenty-three articles published between March 2010 and June 2021 were selected from 195 initially identified records. The findings are discussed in terms of the prevalence of asthma, chronic obstructive pulmonary disease, interstitial lung disease, obstructive sleep apnea, pulmonary hypertension, and sarcoidosis in psoriasis. A higher prevalence of lung diseases in psoriasis has been confirmed in asthma, chronic obstructive pulmonary disease, obstructive sleep apnea, and pulmonary hypertension. These conditions are important as they are previously unrecognized causes of morbidity and mortality in psoriasis. The development of lung diseases in patients with psoriasis can be explained by several mechanisms, including common risk factors, shared immune and molecular characteristics associated with chronic inflammation, as well as other mechanisms. Understanding the prevalence of lung diseases in psoriasis and their underlying mechanisms can help implement appropriate preventative and therapeutic strategies to address respiratory diseases in patients with psoriasis.

Potential therapeutic targets to prevent organ damage in chronic pulmonary sarcoidosis

INTRODUCTION

Sarcoidosis is a granulomatous inflammatory disease with high chances of reduced quality of life, irreversible organ damage, and reduced life expectancy when vital organs are involved. Any organ system can be affected, and the lungs are most often affected. There is no preventive strategy as the exact etiology is unknown, and complex immunogenetic and environmental factors determine disease susceptibility and phenotype. Present-day treatment options originated from clinical practice and are effective in many patients. However, a substantial percentage of patients suffer from unacceptable side effects or still develop refractory, threatening pulmonary or extrapulmonary disease.

AREAS COVERED

As non-caseating granulomas, the pathological hallmark of disease, are assigned to divergent activation and regulation of the immune system, targets in relation to the possible triggers of granuloma formation and their sequelae were searched and reviewed.

EXPERT OPINION

:The immunopathogenesis underlying sarcoidosis has been a dynamic field of study. Several recent new insights give way to promising new therapeutic targets, such as certain antigenic triggers (e.g. from Aspergillus nidulans), mTOR, JAK-STAT and PPARγ pathways, the NRP2 receptor and MMP-12, which await further exploration. Clinical and trigger related phenotyping, and molecular endotyping in sarcoidosis will likely hold the key for precision medicine in the future.

The Role of Diverse Immune Cells in Sarcoidosis

Sarcoidosis is a systemic inflammatory disorder of unknown etiology characterized by tissue infiltration with macrophages and lymphocytes and associated non-caseating granuloma formation. The disease primarily affects the lungs. Patients suffering from sarcoidosis show a wide range of clinical symptoms, natural history and disease outcomes. Originally described as a Th1-driven disease, sarcoidosis involves a complex interplay among diverse immune cells. This review highlights recent advances in the pathogenesis of sarcoidosis, with emphasis on the role of different immune cells. Accumulative evidence suggests Th17 cells, IFN-γ-producing Th17 cells or Th17.1 cells, and regulatory T (Treg) cells play a critical role. However, their specific actions, whether protective or pathogenic, remain to be clarified. Macrophages are also involved in granuloma formation, and M2 polarization may be predictive of fibrosis. Previously neglected cells including B cells, dendritic cells (DCs), natural killer (NK) cells and natural killer T (NKT) cells were studied more recently for their contribution to sarcoid granuloma formation. Despite these advances, the pathogenesis remains incompletely understood, indicating an urgent need for further research to reveal the distinct immunological events in this process, with hope to open up new therapeutic avenues and if possible, to develop preventive measures.

Autophagy and Mitophagy-Related Pathways at the Crossroads of Genetic Pathways Involved in Familial Sarcoidosis and Host-Pathogen Interactions Induced by Coronaviruses

Sarcoidosis is a multisystem disease characterized by the development and accumulation of granulomas, the hallmark of an inflammatory process induced by environmental and/or infectious and or genetic factors. This auto-inflammatory disease mainly affects the lungs, the gateway to environmental aggressions and viral infections. We have shown previously that genetic predisposition to sarcoidosis occurring in familial cases is related to a large spectrum of pathogenic variants with, however, a clustering around mTOR (mammalian Target Of Rapamycin)-related pathways and autophagy regulation. The context of the COVID-19 pandemic led us to evaluate whether such genetic defects may increase the risk of a severe course of SARS-CoV2 infection in patients with sarcoidosis. We extended a whole exome screening to 13 families predisposed to sarcoidosis and crossed the genes sharing mutations with the list of genes involved in the SARS-CoV2 host-pathogen protein-protein interactome. A similar analysis protocol was applied to a series of 100 healthy individuals. Using ENRICH.R, a comprehensive gene set enrichment web server, we identified the functional pathways represented in the set of genes carrying deleterious mutations and confirmed the overrepresentation of autophagy- and mitophagy-related functions in familial cases of sarcoidosis. The same protocol was applied to the set of genes common to sarcoidosis and the SARS-CoV2-host interactome and found a significant enrichment of genes related to mitochondrial factors involved in autophagy, mitophagy, and RIG-I-like (Retinoic Acid Inducible Gene 1) Receptor antiviral response signaling. From these results, we discuss the hypothesis according to which sarcoidosis is a model for studying genetic abnormalities associated with host response to viral infections as a consequence of defects in autophagy and mitophagy processes.

Involvement of Dendritic Cells and Th17 Cells in Induced Tertiary Lymphoid Structures in a Chronic Beryllium Disease Mouse Model

Objective

To study airway pathophysiology and the role of dendritic cells (DCs) and IL-17 receptor (IL-17R) signals in a mouse model for CBD.

Methods

Here, we present a CBD mouse model in which mice were exposed to beryllium during three weeks. We also exposed IL-17R-deficient mice and mice in which DCs were depleted.

Results

Eight weeks after the initial beryllium exposure, an inflammatory response was detected in the lungs. Mice displayed inflammation of the lower airways that included focal dense infiltrates, granuloma-like foci, and tertiary lymphoid structure (TLS) containing T cells, B cells, and germinal centers. Alveolar cell analysis showed significantly increased numbers of CD4⁺ T cells expressing IFNγ, IL-17, or both cytokines. The pathogenic role of IL-17R signals was demonstrated in IL-17R-deficient mice, which had strongly reduced lung inflammation and TLS development following beryllium exposure. In CBD mice, pulmonary DC subsets including CD103⁺ conventional DCs (cDCs), CD11b⁺ cDCs, and monocyte-derived DCs (moDCs) were also prominently increased. We used diphtheria toxin receptor-mediated targeted cell ablation to conditionally deplete DCs and found that DCs are essential for the maintenance of TLS in CBD. Furthermore, the presence of antinuclear autoantibodies in the serum of CBD mice showed that CBD had characteristics of autoimmune disease.

Conclusions

We generated a translational model of sarcoidosis driven by beryllium and show that DCs and IL-17R signals play a pathophysiological role in CBD development as well as in established CBD in vivo.

Inhibiting OX40 Restores Regulatory T-Cell Function and Suppresses Inflammation in Pulmonary Sarcoidosis

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.

Pathogenesis of Non-Infectious Uveitis Elucidated by Recent Genetic Findings

Uveitis is a generic term for inflammation of the uvea, which includes the iris, ciliary body, and choroid. Prevalence of underlying non-infectious uveitis varies by race and region and is a major cause of legal blindness in developed countries. Although the etiology remains unclear, the involvement of both genetic and environmental factors is considered important for the onset of many forms of non-infectious uveitis. Major histocompatibility complex (MHC) genes, which play a major role in human immune response, have been reported to be strongly associated as genetic risk factors in several forms of non-infectious uveitis. Behçet’s disease, acute anterior uveitis (AAU), and chorioretinopathy are strongly correlated with MHC class I-specific alleles. Moreover, sarcoidosis and Vogt-Koyanagi-Harada (VKH) disease are associated with MHC class II-specific alleles. These correlations can help immunogenetically classify the immune pathway involved in each form of non-infectious uveitis. Genetic studies, including recent genome-wide association studies, have identified several susceptibility genes apart from those in the MHC region. These genetic findings help define the common or specific pathogenesis of ocular inflammatory diseases by comparing the susceptibility genes of each form of non-infectious uveitis. Interestingly, genome-wide association of the interleukin (IL)23R region has been identified in many of the major forms of non-infectious uveitis, such as Behçet’s disease, ocular sarcoidosis, VKH disease, and AAU. The interleukin-23 (IL-23) receptor, encoded by IL23R, is expressed on the cell surface of Th17 cells. IL-23 is involved in the homeostasis of Th17 cells and the production of IL-17, which is an inflammatory cytokine, indicating that a Th17 immune response is a common key in the pathogenesis of non-infectious uveitis. Based on the findings from the immunogenetics of non-infectious uveitis, a personalized treatment approach based on the patient’s genetic make-up is expected.

Comprehensive miRNA Analysis Using Serum From Patients With Noninfectious Uveitis

Purpose

MicroRNAs (miRNAs) are noncoding RNAs and have attracted attention as a biomarker in a variety of diseases. However, extensive unbiased miRNAs analysis in patients with uveitis has not been completely explored. In the present study, we comprehensively analyzed the deregulated miRNAs in three major forms of uveitis (Behҫet's disease [BD], sarcoidosis and Vogt–Koyanagi–Harada disease [VKH]) to search for potential biomarkers.

Methods

This study included 10 patients with BD, 17 patients with sarcoidosis, and 13 patients with VKH. Eleven healthy subjects were used as controls. The miRNAs expression levels were studied by microarray using serum samples from patients with uveitis and healthy controls.

Results

A total of 281 upregulated miRNAs and 137 downregulated miRNAs were detected in patients with BD, 35 upregulated miRNAs and 86 downregulated miRNAs in patients with sarcoidosis, and 153 upregulated miRNAs and 35 downregulated miRNAs in patients with VKH. Some deregulated miRNAs were involved in the mitogen-activated protein kinase signaling pathway and inflammatory cytokine pathways. Furthermore, we identified miR-4708-3p, miR-4323, and let-7g-3p as the best predictor miRNAs for BD, sarcoidosis, and VKH, respectively. Panels of miRNAs with diagnostic potential for the three diseases were generated using machine learning.

Conclusions

In this study, comprehensive miRNA analysis identified deregulated miRNAs in three major forms of noninfectious uveitis. This study provides new insights into molecular pathogenetic mechanisms and useful information toward developing novel diagnostic biomarkers and therapeutic targets for BD, sarcoidosis, and VKH.

Sarcoidosis manifesting during treatment with secukinumab for psoriatic arthritis

Sarcoidosis is a multisystem inflammatory disorder of uncertain aetiology. There are numerous case reports of sarcoidosis occurring during treatment with biological immunotherapies. Here, we describe the case of a 52-year-old woman with psoriatic arthritis who developed multisystem sarcoidosis while being treated with secukinumab (anti-interleukin-17A) therapy which, to our knowledge, is the first such case. We discuss existing literature and hypothesise that IL-17 blockade may precipitate the development of granulomatous disease.

Sarcoid-like reaction in cases treated by checkpoint inhibitors

Sarcoidosis is a multisystem granulomatous disorder characterized by helper T cell inflammation. Sarcoid-like reaction (SLR) is a well-defined entity and may be related with several malignant disorders and/or their therapies. SLR has been reported more than 20 years ago and in recent years in cases treated by checkpoint inhibitors (CPIs). Better outcome has been reported in cases developing granulomatous reaction and/or SLRs during CPI treatments. However, these lesions clinically may be thought as disease progression and may cause to stop treatment or alterations. These therapeutic manipulations may be harmful for the patients. Clinicians should be aware of SLRs in cases treated by CPIs and tissues must be sampled and reviewed by an experienced pathologist to avoid misdiagnosis and also unnecessary CPI treatment cessations.Significance StatementClinicians should be aware of sarcoid-like reactions in cases treated by checkpoint inhibitors and tissues must be sampled and reviewed by an experienced pathologist to avoid misdiagnosis and CPI treatment stops.

Biologic and advanced immunomodulating therapeutic options for sarcoidosis: a clinical update

Introduction: Sarcoidosis is a multi-organ disease with a wide range of clinical manifestations and outcomes. A quarter of sarcoidosis patients require long-term treatment for chronic disease. In this group, corticosteroids and cytotoxic agents be insufficient to control diseaseAreas covered: Several biologic agents have been studied for treatment of chronic pulmonary and extra-pulmonary disease. A review of the available literature was performed searching PubMed and an expert opinion regarding specific therapy was developed.Expert opinion: These agents have the potential of treating patients who have progressive disease. Many of these agents have different mechanisms of action, response rates, and toxicity profiles.

Emerging Molecular Targets for the Treatment of Refractory Sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown origin that has variable clinical course and can affect nearly any organ. It has a chronic course in about 25% of patients. Corticosteroids (CS) are the cornerstone of therapy but their long-term use is associated with cumulative toxicity. Commonly used CS-sparing agents include methotrexate, cyclophosphamide, azathioprine, and mycophenolate mofetil. Twenty to forty percentage of sarcoidosis patients are refractory to these therapies or develop severe adverse events. Therefore, additional and targeted CS-sparing agents are needed for chronic sarcoidosis. Macrophage activation, interferon response, and formation of the granuloma are mainly mediated by T helper-1 responses. Different pro-inflammatory cytokines such as interleukin (IL)-8, IL-12, IL-6, and tumor necrosis factor-alpha (TNF-α) have been shown to be highly expressed in sarcoidosis-affected tissues. As a result of increased production of these cytokines, Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling is constitutively active in sarcoidosis. Several studies of biological agents that target TNF-α have reported their efficacy and appear today as a second line option in refractory sarcoidosis. Some case series report a positive effect of tocilizumab an anti-IL-6 monoclonal antibody in this setting. More recently, JAK inhibition appears as a new promising strategy. This review highlights key advances on the management of chronic refractory sarcoidosis. Novel therapeutic strategies and treatment agents to manage the disease are described.

Data Mining Study on Prescription Patterns of Different Dosage Forms of Chinese Herbal Medicines for Treating and Improving Immune-Inflammatory Indices in Patients with Rheumatoid Arthritis

OBJECTIVE

To explore the prescription patterns of different dosage forms of Chinese herbal medicines (CHMs) for the treatment of rheumatoid arthritis (RA) and their effects on immune-inflammatory indices.

METHODS

Clinical data were collected from patients with RA in 4 hospitals (3 Class A comprehensive hospitals and 1 Class B comprehensive hospital) in Anhui Province, China, from August 2012 to June 2018 via the electronic medical record gathering system. Following extraction of prescription information, each prescribed herb was quantified and standardized according to the knowledge base to establish a database of RA treatment formulae. The medical records were divided into the granules group and decoction pieces group. Core herbs and their combination patterns were obtained from the two groups of cases using Liquorice software. Changes in immune-inflammatory and hepatic and renal function indices were compared between the two groups using SPSS 23.0 software. The Aprior module of SPSS Clementine 11.1 software was applied to analyse the correlation between CHMs and improvement in indices. Finally, the ORACLE 10 g tool was used to evaluate the random walk model of the immune-inflammatory indices between the two groups.

RESULTS

(1) We retrospectively analysed 35,898 prescriptions for 6,829 patients with RA who received CHM treatment. There were 3,816 patients in the granules group and 3,013 in the decoction pieces group. (2) The core herbs were Pi (Spleen)-strengthening and dampness-resolving drugs, blood-activating and stasis-resolving drugs, wind/dampness-dispelling drugs and heat-clearing and detoxifying drugs. (3) Both dosage forms could improve immune-inflammatory indices in RA patients, with similar efficacy and no influence on hepatic or renal function. (4) Herba Siegesbeckiae and Oldenlandia had a stronger association with immune-inflammatory indices in the two groups. (5) The immune-inflammatory indices showed obvious improvement after treatment with granules and decoction pieces of CHMs, and there were long range correlations between the comprehensive evaluation indices and interventions.

CONCLUSIONS

The principal CHM treatment methods for RA in four hospitals in Anhui Province are strengthening Pi and resolving dampness, activating blood and resolving stasis, dispelling wind/dampness and clearing heat. Granules and decoction pieces of CHMs have similar efficacy in improving immune-inflammatory indices in RA patients and could be used as treatment options for RA.

Psoriasis and Connective Tissue Diseases

Psoriasis is a chronic systemic inflammatory disease with various co-morbidities, having been recently considered as a comprehensive disease named psoriatic disease or psoriatic syndrome. Autoimmune diseases are one form of its co-morbidities. In addition to the genetic background, shared pathogenesis including innate immunity, neutrophil extracellular trap (NETs), and type I interferon, as well as acquitted immunity such as T helper-17 (Th17) related cytokines are speculated to play a significant role in both psoriasis and connective tissue diseases. On the other hand, there are definite differences between psoriasis and connective tissue diseases, such as their pathomechanisms and response to drugs. Therefore, we cannot expect that one stone kills two birds, and thus caution is necessary when considering whether the administered drug for one disease is effective or not for another disease. In this review, several connective tissue diseases and related diseases are discussed from the viewpoint of their coexistence with psoriasis.

T-bet Expression in Peripheral Th17.0 Cells Is Associated With Pulmonary Function Changes in Sarcoidosis

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.

Th17 lymphocytes in atypical cutaneous leishmaniasis caused by Leishmania (L.) infantum chagasi in Central America

Skin lesions in nonulcerated cutaneous leishmaniasis (NUCL) caused by Leishmania (L.) infantum chagasi are characterized by a mononuclear inflammatory infiltrate in the dermis, which is composed mainly of lymphocytes, followed by macrophages, few plasma cells and epithelioid granulomas with mild tissue parasitism. Previous studies have shown that the main population of lymphocytes present in the dermal infiltrate is CD8⁺ T cells, followed by CD4⁺ T cells, which are correlated with IFN-γ⁺ cells. To improve the knowledge of cellular immune responses in NUCL, skin biopsies were submitted to immunohistochemistry using anti-ROR-γt, anti-IL-17, anti-IL-6, anti-TGF-β, and anti-IL-23 antibodies to characterize the involvement of Th17 cells in the skin lesions of patients affected by NUCL. ROR-γt⁺ , IL-17⁺ , IL-6⁺ , TGF-β⁺ and IL-23⁺ cells were observed in the dermal inflammatory infiltrate of NUCL skin lesions. A positive correlation between CD4⁺ T-lymphocytes and ROR-γt⁺ and IL-17⁺ cells suggests that some of the CD4⁺ T-lymphocytes in NUCL could be Th17 lymphocytes. Moreover, a positive correlation between ROR-γt⁺ cells and TGF-β⁺ , IL-6⁺ , IL-17⁺ and IL-23⁺ cells could indicate the role of these cytokines in the differentiation and maintenance of Th17 lymphocytes. Our findings improve knowledge of the pathogenesis of this rare and atypical clinical form of leishmaniasis.

Spondyloarthritis and sarcoidosis: Related or fake friends? A systematic literature review

BACKGROUND

Sarcoidosis and spondyloarthritis (SpA) have been regularly associated. Bone iliac granulomas have also been described. We propose herein a systematic review of rheumatologic axial manifestations of sarcoidosis.

METHODS

PubMed and the Cochrane Library were used to conduct this systematic literature review. Case reports and cross-sectional studies were reviewed according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

A total of 41 articles were eligible. Three cross-sectional studies on the association between SpA and sarcoidosis showed a prevalence of sacroiliitis and SpA ranging from 12.9 to 44.8% and 12.9 to 48.3% in inflammatory back pain (IBP) subgroups, respectively. However, the IBP definitions and sacroiliac joint (SIJ) imaging modalities (X-rays or magnetic resonance imaging) were heterogeneous, and X-ray was mainly used for sacroiliitis diagnosis (in 78% of cases). Thirty-one case-report articles of the sarcoidosis-sacroiliitis association were identified, representing 35 patients. ASAS criteria for SpA were met in half of cases (16/32) and 46% (12/26) had HLA B27 positivity. Sarcoidosis occurred after sacroiliac symptoms in 47% of cases. In the seven case-report articles with granulomatous sacroiliac bone involvement, unilateral involvement seemed higher than in the sarcoidosis-sacroiliitis group.

CONCLUSION

Literature analysis found a good evidence of the association between SpA and sarcoidosis, and special attention should be given to patients reporting IBP. Unilateral sacroiliitis may raise suspicion of granulomatous bone involvement, distinct from sacroiliitis. Imaging modalities used to study the SIJ in patients with sarcoidosis have been heterogeneous and further investigation is needed.

Sarcoidosis and the mTOR, Rac1, and Autophagy Triad

Sarcoidosis is an enigmatic multisystem disease characterized by the development and accumulation of granulomas: a compact collection of macrophages that have differentiated into epithelioid cells and which are associated with T helper (Th)1 and Th17 cells. Although no single causative factor has been shown to underlie sarcoidosis in humans, its etiology has been related to microbial, environmental, and genetic factors. We examine how these factors play a role in sarcoidosis pathogenesis. Specifically, we propose that dysfunction of mTOR, Rac1, and autophagy-related pathways not only hampers pathogen or nonorganic particle clearance but also participates in T cell and macrophage dysfunction, driving granuloma formation. This concept opens new avenues for potentially treating sarcoidosis and may serve as a blueprint for other granulomatous disorders.

Exploring the imbalance of circulating follicular helper CD4+ T cells in sarcoidosis patients

BACKGROUND

Sarcoidosis is a systemic granulomatous disease characterized by the combination of Th1 and Th17 responses. Recently, several arguments have suggested a potential involvement of B cells as well as T cells in the pathogenesis of sarcoidosis. Follicular helper CD4⁺ T (T_FH) cells are specialized in interacting with and helping B cells, and play a crucial role in the formation of germinal centers.

OBJECTIVE

We sought to explore the status of T_FH cells and investigate their possible pathogenic role in sarcoidosis.

METHODS

T_FH cells and B cells in peripheral blood were examined by flow cytometry, and serum samples were studied by cytokine arrays. Immunohistochemistry was performed to check for the presence of T_FH cells in sarcoidosis skin lesions. Gene expression in isolated T_FH cells was analyzed by quantitative RT-PCR.

RESULTS

The proportion of circulating T_FH cells was decreased. CD4⁺CXCR5⁺ T_FH cells were observed in cutaneous lesions in sarcoidosis. Gene expression in circulating T_FH cells and serum cytokine concentrations related to Th17 were increased in sarcoidosis patients. Gene expressions of B cell differentiation cytokines in T_FH cells were not altered in sarcoidosis patients.

CONCLUSION

We herein describe a decrease of circulating T_FH cells and their migration to affected tissues. Circulating T_FH cells are one of the potential cell types capable of producing IL-17 and enhancing Th17 responses, and may promote the chronic inflammation. We could not demonstrate a direct linkage between the imbalance of T_FH cells and abnormal B cell differentiation in sarcoidosis.

IL-17A Can Promote Propionibacterium acnes-Induced Sarcoidosis-Like Granulomatosis in Mice

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.

Host-microbe interactions in the pathogenesis and clinical course of sarcoidosis

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.

Role of imbalance between Th17 and regulatory T-cells in sarcoidosis

PURPOSE OF REVIEW

A relatively new class of CD4 expressing T cells that also express and release interleukin-17 (Th17 cells) is gaining attention based on their capacity to regulate inflammatory responses in a spectrum of chronic autoimmune diseases. The purpose of this review is to consider recent studies relating to the critical role played by Th17 cells in the pathogenesis of sarcoidosis.

RECENT FINDINGS

Th17 cells are unique in their capacity to adapt to local molecular cues to variably promote or suppress inflammation. On the basis of knowledge established originally in the context of autoimmune disorders, recent investigations indicate that Th17 cells are instrumental in all stages of granuloma evolution, including granuloma formation, maintenance and resolution. Recent research shed light on the mechanisms regulating Th17 cell plasticity and the implications for sarcoidosis disease progression, such as the mechanisms by which regulatory T cells (Tregs) promote resolution of Th17-mediated inflammation.

SUMMARY

The balance between Th17 cells and Tregs in sarcoidosis patients has important implications for clinicians and clinical researchers seeking more reliable prognostic markers and more targeted therapeutic agents.

Two siblings with PRKDC defect who presented with cutaneous granulomas and review of the literature

V(D)J recombination, during which recognition and repair of broken DNA chains are accomplished by non-homologous end joining pathway, is a critical process in B and T cell development.Null mutations of each enzyme or protein of this pathway result in T- B- NK+ severe combined immunodeficiency whereas hypomorphic mutations result in atypical(leaky)severe combined immunodeficiency forms. We present two siblings with PRKDC (Protein Kinase, DNA-Activated, Catalytic Polypeptide) mutation who presented with granulomatous skin lesions and recurrent lung infections. Primary immune deficiencies may initially present with skin findings. Disruption in central and peripheral B-cell tolerance and impaired intrathymic T-cell maturation,a central player in T-cell tolerance, have been identified as the mechanism of autoimmunity and granuloma seen in patients. The variation in clinical phenotypes of patients with PRKDC mutation suggests that additional factors such as modifying genes, epigenetic and environmental factors may affect the severity and clinical phenotype of the disease. Functional studies during the follow-up and evaluation before and after hematopoeitic stem cell transplantation will hopefully increase our knowledge about the autoimmune and inflammatory process of the disease spectrum.

Immune checkpoint inhibitors and the development of granulomatous reactions

Immune checkpoint inhibitors (ICPIs) have emerged as a frontline treatment for a growing list of malignancies. Disruption of the negative regulatory immune checkpoints by ICPIs has been associated with many immune-related adverse events. Granulomatous reactions, such as sarcoidosis-like reactions, granulomatous panniculitis, granuloma annulare, and granulomatous dermatitis, are uncommon but increasingly recognized immune-related adverse events seen in patients treated with ICPIs. The frequency and significance of these eruptions, including whether they portend responsiveness to treatment, remain unclear. Additionally, understanding the role of immune checkpoint blockade in these reactions may provide mechanistic insight into the relevant signaling pathways involved in sarcoidosis and other granulomatous disorders.

Sarcoidosis: a state of the art review from the Thoracic Society of Australia and New Zealand

Sarcoidosis is a systemic disease of unknown aetiology, characterised by non-caseating granulomatous inflammation. It most commonly manifests in the lungs and intrathoracic lymph nodes but can affect any organ. This summary of an educational resource provided by the Thoracic Society of Australia and New Zealand outlines the current understanding of sarcoidosis and highlights the need for further research. Our knowledge of the aetiology and immunopathogenesis of sarcoidosis remains incomplete. The enigma of sarcoidosis lies in its immunological paradox of type 1 T helper cell-dominated local inflammation co-existing with T regulatory-induced peripheral anergy. Although specific aetiological agents have not been identified, mounting evidence suggests that environmental and microbial antigens may trigger sarcoidosis. Genome-wide association studies have identified candidate genes conferring susceptibility and gene expression analyses have provided insights into cytokine dysregulation leading to inflammation. Sarcoidosis remains a diagnosis of exclusion based on histological evidence of non-caseating granulomas with compatible clinical and radiological findings. In recent years, endobronchial ultrasound-guided transbronchial needle aspiration of mediastinal lymph nodes has facilitated the diagnosis, and whole body positron emission tomography scanning has improved localisation of disease. No single biomarker is adequately sensitive and specific for detecting and monitoring disease activity. Most patients do not require treatment; when indicated, corticosteroids remain the initial standard of care, despite their adverse side effect profile. Other drugs with fewer side effects may be a better long term choice (eg, methotrexate, hydroxychloroquine, azathioprine, mycophenolate), while tumour necrosis factor-α inhibitors are a treatment option for patients with refractory disease.

G908R NOD2 variant in a family with sarcoidosis

Background

Sarcoidosis is a systemic disease characterized by the formation of immune granulomas in various organs, mainly the lungs and the lymphatic system. Exaggerated granulomatous reaction might be triggered in response to unidentified antigens in individuals with genetic susceptibility. The present study aimed to determine the genetic variants implicated in a familial case of sarcoidosis.

Methods

Sarcoidosis presentation and history, NOD2 profile, NF-κB and cytokine production in blood monocytes/macrophages were evaluated in individuals from a family with late appearance of sarcoidosis.

Results

In the present study, we report a case of familial sarcoidosis with typical thoracic sarcoidosis and carrying the NOD2 2722G > C variant. This variant is associated with the presence of three additional SNPs for the IL17RA, KALRN and EPHA2 genes, which discriminate patients expressing the disease from others. Despite a decrease in NF-κB activity, IL-8 and TNF-A mRNA levels were increased at baseline and in stimulated conditions.

Conclusions

Combination of polymorphisms in the NOD2, IL17RA, EPHA2 and KALRN genes could play a significant role in the development of sarcoidosis by maintaining a chronic pro-inflammatory status in macrophages.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0748-5) contains supplementary material, which is available to authorized users.