The immune paradox of sarcoidosis and regulatory T cells

Associations of peripheral blood lymphopenia to disease course, treatment and TNF-α in sarcoidosis

BACKGROUND

Severe sarcoidosis has been associated with peripheral blood (PB) total lymphopenia and high tumour necrosis factor α (TNF-α) levels, and the lymphopenia phenotype seems to respond poorly to conventional treatment. However, the mechanisms behind PB lymphopenia and its correlation with TNF-α levels remain unclear. Understanding the connections among PB lymphocyte subsets, TNF-α and clinical phenotype including treatment status could offer insights into how to individualize therapy.

METHODS

PB samples from 65 consecutive sarcoidosis patients were collected at the Department of Respiratory Medicine, Karolinska University Hospital. Total lymphocyte, T-, B- and natural killer cell and TNF-α serum concentrations were measured and correlated to clinical parameters. Penias were defined as values below the lower limit of normal. The medical charts were retrospectively searched for the first PB total lymphocyte count, mostly recorded at time around diagnosis.

RESULTS

PB total lymphopenia was observed in 35% of patients, was present since time around diagnosis, and associated with a need for treatment later (p = 0.005). Lymphocyte counts did not change by therapy, except for an increase in patients receiving TNF-α inhibitors (TNFi) (p < 0.05). B-cell penia, observed in 37% of patients, was the most common abnormality, also in patients with normal total lymphocyte counts, while T-cell penia mainly occurred in patients with total lymphopenia (91 vs 5%, p < 0.001).

CONCLUSIONS

B-cell penia is common in sarcoidosis patients while T-cell penia is mainly a feature of the sarcoidosis PB lymphopenia phenotype. Increased lymphocyte counts during TNFi treatment suggests that TNF-α signaling is of importance for sarcoidosis associated lymphopenia.

The abundance of regulatory T cell subsets is associated with the clinical outcomes of sarcoidosis

OBJECTIVES

Some patients with sarcoidosis achieve spontaneous remission, whereas others repeatedly experience relapse. We examined differences in the clinical course of active sarcoidosis according to peripheral blood immunophenotypes before treatment.

METHODS

This retrospective study compared peripheral blood immunophenotypes between patients with active sarcoidosis (n = 28) and healthy control subjects (n = 10). Patients with sarcoidosis were divided into the spontaneous remission group without treatment (n = 9), the non-relapsed group after treatment (n = 13), and the relapsed group after treatment (n = 6) and were compared for peripheral blood immunophenotypes and background characteristics at baseline.

RESULTS

Patients with sarcoidosis showed increases in activated T helper (Th) 1 cells, activated Th17 cells, and regulatory T (Treg) cell subsets. The proportion of effector Treg cells was highest in the spontaneous remission group, and the proportion of non-suppressive Treg cells was highest in the relapsed group. No differences were observed in the proportions of other CD4+ T cell subsets. The cut-off values for predicting spontaneous remission and relapse were calculated for the effector Treg/non-suppressive Treg ratio. As a result, A ratio ≥1.469 predicted spontaneous remission (75%), while ≤0.722 predicted relapse (66.7%).

CONCLUSION

Effector and non-suppressive Treg cell proportions before treatment may predict spontaneous remission and relapse in active sarcoidosis.

Imaging in sarcoid disease

Sarcoidosis is a complex multisystem inflammatory disease characterized by noncaseating granulomas and variable clinical manifestations, most commonly affecting the lungs, skin, heart, and nervous system. Imaging is central in its diagnosis, staging, and management, providing essential insights into organ involvement and disease activity. Pulmonary manifestations remain the hallmark, with modalities such as high-resolution chest computed tomography (CT) and chest radiography offering critical diagnostic clues. Imaging techniques, including Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) and cardiac magnetic resonance imaging, are invaluable for identifying cardiac and systemic involvement, including cutaneous and musculoskeletal, while abdominal MRI and ultrasound help delineate hepatic and splenic manifestations. Neurosarcoidosis requires MRI for precise evaluation, supplemented by FDG-PET to guide biopsy and monitor treatment response. This chapter synthesizes the imaging features of sarcoidosis across organ systems, emphasizing practical approaches to diagnosis and management while identifying key areas for future research.

Network Pharmacology-driven therapeutic interventions for Interstitial Lung Diseases using Traditional medicines: A Narrative Review

This review explores the progressive domain of network pharmacology and its potential to revolutionize therapeutic approaches for Interstitial Lung Diseases (ILDs), a collective term encompassing Interstitial Pneumonia, Pneumoconiosis, Connective Tissue Disease-related ILDs, and Sarcoidosis. The exploration focuses on the profound legacy of traditional medicines, particularly Ayurveda and Traditional Chinese Medicines (TCM), and their largely unexplored capacity in ILD treatment. These ancient healing systems, characterized by their holistic methodologies and multifaceted treatment modalities, offer a promising foundation for discovering innovative therapeutic strategies. Moreover, the review underscores the amalgamation of artificial intelligence (AI) and machine learning (ML) methodologies with bioinformatics, creating a computational synergy capable of deciphering the intricate biological networks associated with ILDs. Network pharmacology has tailored the hypothesis from the conventional "one target, one drug" towards a "network target, multi-component therapeutics" approach. The fusion of traditional literature and computational technology can unveil novel drugs, targets, and pathways, augmenting effective therapies and diminishing adverse effects related to current medications. In conclusion, this review provides a comprehensive exposition of how Network Pharmacology tools can leverage the insights of Ayurveda and TCM to craft efficacious therapeutic solutions for ILDs. It sets the stage for future investigations in this captivating interdisciplinary domain, validating the use of traditional medicines worldwide.

Phenotypes and Endotypes in Sarcoidosis: Unraveling Prognosis and Disease Course

Sarcoidosis is a multi-system granulomatous disease of unknown etiology. In genetically susceptible individuals, the precipitating factors generate, via immunity mechanisms, a host granulomatous response. The granuloma, for unknown reasons thus far, may resolve or may persist and lead to organ damage and fibrosis. Infectious agents, occupational exposure, obesity, smoking and genetic factors are implicated in the pathogenesis of sarcoidosis. Macrophages are important in granuloma formation, and their M1/M2 phenotype is associated with the prognosis of the disease. CD4+ T helper cells play a central role in the pathogenesis of sarcoidosis. The major contributors appear to be Th1 and Th17.1 cells, whose microenvironmental behavior is dictated by the secretions of macrophages and dendritic cells. Higher levels of Th1 and Th17.1 cells are associated with chronic disease and resistance to corticosteroid treatment. In recent years, advances in the phenotyping of sarcoidosis with the help of HRCT, PET-CT and lung function tests have provided us with a better understanding of the disease. Genetic phenotyping performed by the GenPhenReSa consortium and the SAGA study has led to the recognition of new, distinct phenotypes. The reconstitution of dysregulated autophagy through persistent m-TORC-1 pathways may be a new treatment target in sarcoidosis.

Developmental drugs for sarcoidosis

Sarcoidosis is a multi-organ granulomatous inflammatory disease of unknown etiology. Over 50% of patients will require treatment at some point in their disease and 10%-30% will develop a chronic progressive disease with pulmonary fibrosis leading to significant morbidity and mortality. Recently published guidelines recommend immunosuppressive therapy for sarcoidosis patients at risk of increased disease-related morbidity and mortality, and in whom disease has negatively impacted quality of life. Prednisone the currently recommended first line therapy is associated with significant toxicity however none of the other guideline recommended steroid sparing therapy is approved by regulatory agencies for use in sarcoidosis, and data in support of their use is weak. For patients with severe refractory disease requiring prolonged therapy, treatment options are limited. The need for expanding treatment options in sarcoidosis has been emphasized. Well conducted large, randomized trials evaluating currently available therapeutic options as well as novel pathways for targeting disease are necessary to better guide treatment decisions. These trials will not be without significant challenges. Sarcoidosis is a rare disease with heterogenous presentation and variable progression and clinical outcome. There are no universally agreed upon biomarkers of disease activity and measurement of outcomes is confounded by the need to balance patient centric measures and objective measures of disease activity. Our paper provides an update on developmental drugs in sarcoidosis and outlines several novel pathways that may be targeted for future drug development. Currently available trials are highlighted and ongoing challenges to drug development and clinical trial design are briefly discussed.

The immunopathogenesis of sarcoidosis

Sarcoidosis is a granulomatous multiorgan disease, thought to result from exposure to yet unidentified antigens in genetically susceptible individuals. The exaggerated inflammatory response that leads to granuloma formation is highly complex and involves the innate and adaptive immune system. Consecutive immunological studies using advanced technology have increased our understanding of aberrantly activated immune cells, mediators and pathways that influence the formation, maintenance and resolution of granulomas. Over the years, it has become increasingly clear that disease immunopathogenesis can only be understood if the clinical heterogeneity of sarcoidosis is taken into consideration, along with the distribution of immune cells in peripheral blood and involved organs. Most studies offer an immunological snapshot during disease course, while the cellular composition of both the circulation and tissue microenvironment may change over time. Despite these challenges, novel insights on the role of the immune system are continuously published, thus bringing the field forward. This review highlights current knowledge on the innate and adaptive immune responses involved in sarcoidosis pathogenesis, as well as the pathways involved in non-resolving disease and fibrosis development. Additionally, we describe proposed immunological mechanisms responsible for drug-induced sarcoid like reactions. Although many aspects of disease immunopathogenesis remain to be unraveled, the identification of crucial immune reactions in sarcoidosis may help identify new treatment targets. We therefore also discuss potential therapies and future strategies based on the latest immunological findings.

Residential fungal β-(1,3)-D-glucan exposure is associated with decreased pulmonary function in fibrotic pulmonary sarcoidosis

Background

Sarcoidosis is a multi-system disease frequently affecting the lungs. It is thought to be mediated by gene-environment interaction; for example, epidemiological data show organic aerosol exposure increases risk of pulmonary sarcoidosis.

Research Question

Does exposure to bioaerosol associate with worse lung disease in patients with pulmonary sarcoidosis?

Research Question

Using an observational, cohort study design, we measured residential exposure to fungal and bacterial cell wall material, β-(1,3)-D-glucan (BDG) and endotoxin, respectively, in healthy control subjects and those with pulmonary sarcoidosis. In the case cohort, we compared bioaerosol concentrations to pulmonary disease severity, assessed by pulmonary function testing, qualitative chest computed tomography (CT), and serum biomarkers. Log-transformed bioaerosol concentrations were compared to lung function and significance and correlation determined by Pearson correlation.

Results

Homes of subjects with sarcoidosis had higher BDG and endotoxin concentrations than control subjects. Patients with significant pulmonary fibrosis had greater disease severity (Wasfi severity score, visual analogue scale) and reduced pulmonary function compared to those without fibrosis (all P<0.01). Residential fungal BDG correlated with declining FVC, only in patients with fibrosis on CT imaging (P=0.02). Survey data revealed higher BDG concentrations were found in homes of cat-owners, and the number of houseplants owned correlated with declines in FVC and FEV1 (P=0.05 and 0.02, respectively). In patients without fibrosis, eight inflammatory markers correlated with BDG (6CKine/CCL21, IL-9, IL-17F, IL-21, IL-28A, I-309, MIP-1β, TARC), while in those with pulmonary fibrosis, BDG correlated with two inflammatory markers (Eotaxin-3, M-CSF), suggesting immune anergy to inhaled antigens in patients with fibrosis.

Interpretation

In patients with pulmonary fibrosis, disease severity was correlated with residential exposure to fungal cell wall material, but not gram-negative bacterial cell wall material. These patients may experience immune anergy to inhaled antigens.

Lung fibrosis in sarcoidosis. Is there a place for antifibrotics?

Sarcoidosis, an enigmatic disease with unknown etiology, is characterized by inflammation and the potential involvement of various organs, predominantly the lungs and intrathoracic lymph nodes. Non-caseating granulomas can resolve spontaneously in approximately 60% of cases within 2-3 years. However, sarcoidosis-related mortality has increased. Lung fibrosis, affecting up to 20% of sarcoidosis patients, stands out as a primary cause of mortality. Traditionally, fibrosis is viewed because of prolonged inflammation, necessitating anti-inflammatory treatment with systemic steroids, immunosuppressants, and anti-TNF agents to manage the disease. The recent introduction of antifibrotic drugs such as nintedanib and pirfenidone offers new avenues for treating fibrotic sarcoidosis. Nintedanib, effective in idiopathic pulmonary fibrosis (IPF) and systemic sclerosis-related interstitial lung disease (SSc-ILD), has shown promise in patients with various progressive fibrosing interstitial lung diseases (PF-ILD), including those with sarcoidosis. Pirfenidone, also effective in IPF, has demonstrated potential in managing fibrotic sarcoidosis, though results have been inconclusive due to limited participant numbers in studies. This review explores the theoretical and empirical evidence supporting the use of antifibrotics in sarcoidosis, weighing the benefits and drawbacks. While antifibrotics offer a potential therapeutic approach, further randomized controlled trials are essential to determine their efficacy in fibrotic sarcoidosis. Addressing fibrosis as a continuum of chronic inflammation, the role of antifibrotics in managing sarcoidosis remains an area requiring more in-depth research to improve patient outcomes and advance treatment paradigms.

Analysis of Immune Cell Subsets in Peripheral Blood from Patients with Engineered Stone Silica-Induced Lung Inflammation

Silicosis caused by engineered stone (ES-silicosis) is an emerging worldwide issue characterized by inflammation and fibrosis in the lungs. To our knowledge, only a few reports have investigated leukocyte/lymphocyte subsets in ES-silicosis patients. The present study was designed to explore the proportions of the main lymphocyte subsets in ES-silicosis patients stratified into two groups, one with simple silicosis (SS) and the other with a more advanced state of the disease, defined as progressive massive fibrosis (PMF). The proportions of B (memory and plasmablasts) cells, T (helper, cytotoxic, regulatory) cells, and natural killer (NK) (regulatory and cytotoxic) cells were investigated by multiparameter flow cytometry in 91 ES-silicosis patients (53 SS patients and 38 PMF patients) and 22 healthy controls (HC). Although the total number of leukocytes did not differ between the groups studied, lymphopenia was observed in patients compared to healthy controls. Compared with those in healthy controls, the proportions of memory B cells, naïve helper T cells, and the CD4+/CD8+ T cells' ratio in the peripheral blood of patients with silicosis were significantly decreased, while the percentages of plasma cells, memory helper T cells, and regulatory T cells were significantly increased. For the NK cell subsets, no significant differences were found between the groups studied. These results revealed altered cellular immune processes in the peripheral blood of patients with ES-silicosis and provided further insight into silicosis pathogenesis.

Hematologic and Oncologic Aspects of Sarcoidosis: Some of the Least Studied but Most Common Dilemmas

The hematologic system is frequently involved in sarcoidosis. Lymphopenia is the most common hematologic manifestation noted, although anemia and thrombocytopenia also occur. The etiology of these common manifestations can be direct granulomatous infiltration of bone marrow, lymph nodes, or spleen or related to immunologic dysfunction. Although not life threatening, these problems can lead to cytopenias requiring close monitoring in patients receiving a variety of disease treatments. The relationship between sarcoidosis and malignancy remains complex. However, some sarcoidosis patients are at increased risk for the development of malignancies, particularly lymphomas and gastrointestinal cancers. Conversely, cancer patients can experience an increase in the likelihood for the development of breast cancer and lymphomas.

Anti-inflammatory Therapy for Sarcoidosis

Over 50% of patients with sarcoidosis will require anti-inflammatory therapy at some point in their disease course. Indications for therapy are to improve health-related quality of life, prevent or arrest organ dysfunction (or organ failure) or avoid death. Recently published treatment guidelines recommended a stepwise approach to therapy however there are some patients for whom up front combination or more intense therapy maybe reasonable. The last decade has seen an explosion of studies and trials evaluating novel therapeutic agents and treatment strategies. Currently available anti-inflammatory therapies and several novel therapies are discussed here.

MIF modulates p38/ERK phosphorylation via MKP-1 induction in sarcoidosis

Macrophage migration inhibitory factor (MIF) is a versatile cytokine that influences a variety of cellular processes important for immune regulation and tissue homeostasis. Sarcoidosis is a granulomatous disease characterized by extensive local inflammation and increased T helper cell mediated cytokines. We have shown that MIF has a modulatory role in cytokine networks in sarcoidosis. We investigated the effect of exogenous MIF on sarcoidosis alveolar macrophages (AMs), CD14+ monocytes and peripheral blood mononuclear cells (PBMCs). Our results showed that MIF negatively regulates the increased MAPKs (pp38 and pERK1/2) activation by inducing Mitogen-activated protein kinase phosphatase (MKP)-1. We found that MIF decreased IL-6 and IL-1β production, increased the percentage of regulatory T-cells (Tregs), and induced IL-1R antagonist (IL-1RA) and IL-10 production. Thus, the results of our study suggest that exogenous MIF modulates MAPK activation by inducing MKP-1and Tregs as well as IL-10 and IL-1RA, and hence plays a modulatory role in immune activation in sarcoidosis.

Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis

Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas. Despite major steps in understanding the cause of this disease, many questions remain. In this Review, we perform a mechanistic interrogation of the immune activities that contribute to granuloma formation in sarcoidosis and compare these processes with its closest mimic, tuberculosis, highlighting shared and divergent immune activities. We examine how Mycobacterium tuberculosis is sensed by the immune system; how the granuloma is initiated, formed, and perpetuated in tuberculosis compared with sarcoidosis; and the role of major innate and adaptive immune cells in shaping these processes. Finally, we draw these findings together around several recent high-resolution studies of the granuloma in situ that utilized the latest advances in single-cell technology combined with spatial methods to analyze plausible disease mechanisms. We conclude with an overall view of granuloma formation in sarcoidosis.

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.

Clinical Manifestations and Management of Fibrotic Pulmonary Sarcoidosis

Fibrotic pulmonary sarcoidosis represents a distinct and relatively uncommon manifestation within the spectrum of sarcoidosis and has substantial morbidity and mortality. Due to the scarcity of research focused on this specific disease subtype, our current understanding of pathogenesis and optimal management remains constrained. This knowledge gap underscores the need for further investigation into areas such as targeted therapies, lung transplantation, and quality of life of patients with fibrotic pulmonary sarcoidosis. The primary aim of this review is to discuss recent developments within the realm of fibrotic pulmonary sarcoidosis to foster a more comprehensive understanding of the underlying mechanisms, prognosis, and potential treatment modalities.

FOXP3+ regulatory T cells are associated with the severity and prognosis of sarcoidosis

Rationale

Sarcoidosis is an inflammatory granulomatous disease of unknown etiology with predominant lung involvement. Organ involvement and disease severity, as well as the nature of immune alterations, vary among patients leading to a range of clinical phenotypes and outcomes. Our objective was to evaluate the association of disease course and immune responses in pulmonary sarcoidosis.

Methods

In this prospective cohort study of 30 subjects, most of whom were followed for one year, we evaluated 14 inflammatory markers in plasma, 13 Treg/T cell flow cytometry markers and 8 parameters of FOXP3+ Treg biology, including suppressive function, epigenetic features and stability.

Results

We identified a set of 13 immunological parameters that differ in sarcoidosis subjects in comparison with healthy donors. Five of those were inversely correlated with suppressive function of Tregs in sarcoidosis, and six (TNFα, TNFR I and II, sCD25, Ki-67 and number of Tregs) were particularly upregulated or increased in subjects with thoracic lymphadenopathy. Treg suppressive function was significantly lower in patients with thoracic lymphadenopathy, and in patients with higher burdens of pulmonary and systemic symptoms. A combination of five inflammatory markers, Ki-67 expression, Treg function, and lung diffusion capacity evaluated at study entry predicted need for therapy at one year follow-up in 90% of cases.

Conclusion

Tregs may suppress ongoing inflammation at local and systemic levels, and TNFα, TNFR I and II, sCD25 and Ki-67 emerge as attractive biomarkers for in vivo sarcoid inflammatory activity.

Lymphopenia and high Ki-67 expression in peripheral blood CD4+ and CD8+ T cells associate with progressive sarcoidosis

BACKGROUND

Early identification of patients at risk for progressive sarcoidosis may improve intervention. High bronchoalveolar lavage fluid (BALF) lymphocytes and peripheral blood (PB) lymphopenia are associated with worse prognosis. The mechanisms behind are not disentangled, and to date, it is not possible to predict disease course with certainty.

OBJECTIVES

Insight into the frequency of T regulatory cells (Tregs), proliferating CD4+ and CD8+ T cells in BALF and PB in clinically well-characterised patients, may provide clues to mechanisms behind differences in disease course.

METHODS

Nineteen treatment-naïve patients with newly diagnosed sarcoidosis were assessed with BAL and PB samples at diagnosis. From the majority, repeated PB samples were collected over a year after diagnosis. The patients were followed for a median of 3 years and clinical parameters were used to classify patients into resolving, chronic progressive and chronic stable disease. Lymphocyte counts, frequency of Tregs defined as forkhead box protein 3+ (FoxP3+) CD4+T cells, and proliferating CD4+ and CD8+ T cells assessed with Ki-67 were analysed.

RESULTS

Eleven patients disclosed a chronic stable, and eight a progressive disease course, no one resolved during the study period. In PB, lower number of lymphocytes associated with chronic progressive disease, an increased frequency of Ki-67+CD4+ and CD8+ T cells, and a tendency towards higher percentage of FoxP3+CD4+ T cells compared with chronic stable patients.

CONCLUSION

A reduction of PB lymphocytes despite increased proliferation of CD4+and CD8+ T cells was observed in patients with chronic active compared with chronic stable sarcoidosis, indicating an increased PB lymphocyte turn-over in patients with deteriorating disease. Measurement of PB Tregs, Ki-67+CD4+ and Ki-67+CD8+ T cells may help in predicting sarcoidosis disease course.

Mediastinal Abscess Formation after EUS-Guided Sampling in a Young Patient with Sarcoidosis: Be Aware of the Increased Risk!

International guidelines establish EUS-guided sampling as safe and accurate for the evaluation of mediastinal solid lesions, such as lymphadenopathies of unknown origin, and point out an increased risk of severe infectious complications induced by needle puncture in mediastinal cystic lesions. A retrospective case series and a systematic review documented an increased risk of mediastinal abscess formation after EUS-guided lymph nodes sampling in patients with sarcoidosis. The authors describe a case of a 38-year-old male patient with a final diagnosis of sarcoidosis, who developed a large mediastinal abscess after EUS-guided fine-needle biopsy of mediastinal lymphadenopathies. Endoscopists should be aware of the potential increased risk of severe infectious complications when sampling mediastinal lymph nodes in suspected sarcoidosis, and a strategy to minimize such risk should be pursued.

Peripheral blood lymphopenia in sarcoidosis associates with HLA-DRB1 alleles but not with lung immune cells and organ involvement

Different human leukocyte antigen (HLA) alleles associate with disease phenotypes in sarcoidosis. Peripheral blood (PB) lymphopenia is reported as more common in sarcoidosis patients with worse prognosis. The mechanisms behind are unrecognized but a PB depletion due to lymphocytes migrating to lung and/or extra pulmonary organs has been suggested. Insights into associations between HLA alleles, lung immune cells, clinical phenotype including extra pulmonary manifestations (EPM), and PB lymphopenia may provide mechanistic clues and enable adequate intervention in this patient group. In this situdy,141 treatment naïve, newly diagnosed patients were retrospectively identified in a Swedish cohort of sarcoidosis patients. Data on HLA-DRB1 alleles, lung immune cells from bronchoalveolar lavage fluid (BALF), PB lymphocytes and clinical parameters including treatment and disease course (chronic vs. resolving) were collected. The patients were followed for 2 years. PB lymphopenia associated with male sex, development of non-resolving disease, a need for first- and second-line systemic immunosuppressant treatment and HLA- DRB1*07. No correlation between BALF and PB lymphocytes, and no difference in EPM was detected between patients with and without PB lymphopenia. In conclusion, PB lymphopenia is associated with a more severe disease phenotype and carriage of the HLA-DRB1*07 allele. The results do not lend support to the hypothesis about sarcoidosis PB lymphopenia being due to a migration of PB lymphocytes to other organs. Rather, they provide a basis for future studies on the connection between HLA-DRB1*07 and PB lymphopenia mechanisms.

Airborne occupational exposures associated with pulmonary sarcoidosis: a systematic review and meta-analysis

The aetiology and pathophysiology of sarcoidosis is ill defined-current hypotheses centre on complex genetic-immune-environmental interactions in an individual, triggering a granulomatous process. The aim of this systematic review is to define and describe which airborne occupational exposures (aOE) are associated with and precede a diagnosis of pulmonary sarcoidosis. The methodology adopted for the purpose was systematic review and meta-analyses of ORs for specified aOE associated with pulmonary sarcoidosis (DerSimonian Laird random effects model (pooled log estimate of OR)). Standard search terms and dual review at each stage occurred. A compendium of aOE associated with pulmonary sarcoidosis was assembled, including mineralogical studies of sarcoidosis granulomas. N=81 aOE were associated with pulmonary sarcoidosis across all study designs. Occupational silica, pesticide and mould or mildew exposures were associated with increased odds of pulmonary sarcoidosis. Occupational nickel and aluminium exposure were associated with a non-statistically significant increase in the odds of pulmonary sarcoidosis. Silica exposure associated with pulmonary sarcoidosis was reported most frequently in the compendium (n=33 studies) and was the most common mineral identified in granulomas. It was concluded that aOE to silica, pesticides and mould or mildew are associated with increased odds of pulmonary sarcoidosis. Equipoise remains concerning the association and relationship of metal dusts with pulmonary sarcoidosis.

Immunological Pathways in Sarcoidosis and Autoimmune Rheumatic Disorders-Similarities and Differences in an Italian Prospective Real-Life Preliminary Study

BACKGROUND

The pathogenesis of sarcoidosis involves T cells and B lymphocytes that produce autoantibodies. We compared the expression of different T and B cell subsets in sarcoidosis and three B-mediated rheumatic diseases that can affect the lungs in an attempt to identify similarities and differences that distinguish these diseases.

METHODS

The study included patients referred to Siena University Hospital's respiratory disease and rheumatology units. Patients were enrolled prospectively and consecutively. Healthy volunteers were also included. Multicolor flow cytometry was performed on phenotype T and B cell subsets. Multivariate analysis was carried out to reduce the dimensionality of the data.

RESULTS

Fifteen patients had a diagnosis of sarcoidosis, fourteen idiopathic inflammatory myopathies (IIM), five granulomatosis with polyangiitis (GPA), ten microscopic polyangiitis (MPA), and seven were controls. Thirty-five T and B cell subsets were phenotyped, 15 of which were significantly different in sarcoidosis, B-mediated rheumatic disorders, and controls. Principal components analysis distinguished the four groups of patients with a total explained variance of 54.7%. A decision tree was constructed to determine which clustering variables would be most useful for distinguishing sarcoidosis, IIM, MPA, and GPA. The model showed regulatory T helper cells (Th-reg) > 5.70% in 91% of sarcoidosis patients as well as Th-reg ≤ 5.70 and Th17 > 43.27 in 100% of MPA. It also showed Th-reg ≤ 5.70, Th17 ≤ 43.27 and Tfh-reg ≥ 7.81 in 100% of GPA patients, and Th-reg ≤ 5.70, Th17 ≤ 43.27 and Tfh-reg ≤ 7.81 in 100% of IIM patients.

CONCLUSION

The immune cell profile sheds light on similarities and differences between sarcoidosis and B-mediated rheumatic diseases. Sarcoidosis and autoimmune diseases show similar patterns of cellular immune dysregulation, suggesting a common pathogenic pathway that may provide an opportunity for further understanding autoimmunity and exploring biological therapies to treat sarcoidosis.

Inhibition of phosphoinositide‑3 kinases γ/δ ameliorates pulmonary granuloma by rescuing Treg function in a sarcoidosis model

Sarcoidosis is a multisystem inflammatory disease characterized by the development of Th1/Th17/regulatory T cells (Tregs)-related non-caseating granulomas. Phosphoinositide-3 kinases δ/γ (PI3Kδ/γ) play an important role in the maintenance of effective immunity, especially for Tregs homeostasis and stability. In the present study, superoxide dismutase A (SodA) stimulation was used to establish the sarcoidosis mouse model. The second immune stimulus was accompanied by CAL-101 (PI3Kδ inhibitor) or AS-605240 (PI3Kδ/γ inhibitor) treatment. To detect the effect of the PI3Kδ/γ inhibitor on the morphology of pulmonary granuloma and the activation of the PI3K signaling pathway, hematoxylin and eosin staining and immunofluorescence and western blotting was used, respectively. Fluorescence-activated cell sorting analysis and reverse transcription-quantitative PCR were adopted to detect the effect of the PI3Kδ/γ inhibitor on the SodA-induced sarcoidosis mouse model in respect to immune cell disorder and the function of Treg cells, with CD4⁺CD25^- T cells and CD4⁺CD25⁺ T cells sorted by magnetic cell sorting. The results demonstrated that the inhibition of PI3Kδ/γ by transtracheal CAL-101/AS-605240 administration facilitated pulmonary granuloma formation. These therapeutic effects were associated with certain mechanisms, including suppressing the aberrantly activated PI3K/Akt signaling in both pulmonary granuloma and Tregs, particularly rescuing the suppressive function of Tregs. Notably, CAL-101 was more effective in immune modulation compared with AS-605240 and could overcome the aberrantly activated Akt in the lung and Tregs. These results suggest that PI3K/Akt signaling, especially the PI3Kδ subunit, can play a key role in optimal Tregs-mediated protection against pulmonary sarcoidosis. Therefore, transtracheal usage of PI3Kδ/γ inhibitors is an attractive therapy that may be developed into a new immune-therapeutic principle for sarcoidosis in the future.

Sarcoidosis and Autoimmune Inflammatory Syndrome Induced by Adjuvants

Currently, sarcoidosis remains one of the diseases with unknown etiology, which significantly complicates its diagnosis and treatment. Various causes of sarcoidosis have been studied for many years. Both organic and inorganic trigger factors, provoking the development of granulomatous inflammation are considered. However, the most promising and evidence-based hypothesis is the development of sarcoidosis as an autoimmune disease, provoked by various adjuvants in genetic predisposed individuals. This concept fits into the structure of the autoimmune/inflammatory syndrome, induced by adjuvants (ASIA) that was proposed in 2011 by Professor Shoenfeld Y. In this paper, the authors reveal the presence of major and minor ASIA criteria for sarcoidosis, propose a new concept of the course of sarcoidosis within the framework of ASIA, and point out the difficulties in creating a model of the disease and the selection of therapy. It is obvious that the data obtained not only bring us closer to understanding the nature of sarcoidosis, but also potentiate new studies confirming this hypothesis by obtaining a model of the disease.

Circulating Regulatory T Cell Subsets in Patients with Sarcoidosis

Over recent years, many researchers have supported the autoimmune theory of sarcoidosis. The presence of uncontrolled inflammatory response on local and system levels in patients with sarcoidosis did not define that the immunoregulatory mechanisms could be affected. The aim of this study was to evaluate the distribution and the disturbance circulating Treg cell subsets in the peripheral blood in patients with sarcoidosis.

MATERIALS AND METHODS

A prospective comparative study was performed in 2016-2018 (34 patients with sarcoidosis (men (67.6%), women (32.3%)) were examined). Healthy subjects-the control group (n = 40). The diagnosis of pulmonary sarcoidosis was performed according to the standard criteria. We used two ten-color combinations of antibodies for Treg immunophenotyping. The first one contained CD39-FITC, CD127-PE, CCR4-PE/Dazzle™ 594, CD25-PC5.5, CD161-PC7, CD4-APC, CD8-APC-AF700, CD3-APC/Cy7, HLA-DR-PacBlue, and CD45 RA-BV 510™, while the second consisted of CXCR3-Alexa Fluor 488, CD25-РЕ, CXCR5-РЕ/Dazzle™ 594, CCR4-PerСP/Сy5.5, CCR6-РЕ/Cy7, CD4-АPC, CD8 АPC-AF700, CD3-АPC/Cy7, CCR7-BV 421, and CD45 RA-BV 510. The flow cytometry data were analyzed by using Kaluza software v2.3. A statistical analysis was performed with Statistica 7.0 and GraphPad Prism 8 software packages.

RESULTS OF THE STUDY

Primarily, we found that patients with sarcoidosis had decreased absolute numbers of Treg cells in circulation. We noted that the level of CCR7-expressing Tregs decreased in patients with sarcoidosis vs. the control group (65.55% (60.08; 70.60) vs. 76.93% (69.59; 79.86) with p < 0.001). We noticed that the relative numbers of CD45RA-CCR7+ Tregs decreased in patients with sarcoidosis (27.11% vs. 35.43%, p < 0.001), while the frequency of CD45 RA-CCR7- and CD45RA+ CCR7- Tregs increased compared to the control group (33.3% vs. 22.73% and 0.76% vs. 0.51% with p < 0.001 and p = 0.028, respectively). CXCR3-expressing Treg cell subsets-Th1-like CCR60078CXCR3+ Tregs and Th17.1-like CCR6+ CXCR3+ Tregs-significantly increased in patients with sarcoidosis vs. the control group (14.4% vs. 10.5% with p < 0.01 and 27.9% vs. 22.8% with p < 0.01, respectively). Furthermore, the levels of peripheral blood EM Th17-like Tregs significantly decreased in the sarcoidosis group vs. the control group (36.38% vs. 46.70% with p < 0.001). Finally, we found that CXCR5 expression was increased in CM Tregs cell subsets in patients with sarcoidosis.

CONCLUSIONS

Our data indicated a decrease in circulating Tregs absolute numbers and several alterations in Treg cell subsets. Moreover, our results highlight the presence of increased levels of CM CXCR5+ follicular Tregs in the periphery that could be linked with the imbalance of follicular Th cell subsets and alterations in B cell, based on the immune response. The balance between the two functionally distinct Treg cell populations-Th1-like and Th17-like Tregs-could be used in sarcoidosis diagnosis and the determination of prognosis and disease outcomes. Furthermore, we want to declare that analysis of Treg numbers of phenotypes could fully characterize their functional activity in peripherally inflamed tissues.

Mycobacterial Heat Shock Proteins in Sarcoidosis and Tuberculosis

Pathological similarities between sarcoidosis (SA) and tuberculosis (TB) suggest the role of mycobacterial antigens in the etiopathogenesis of SA. The Dubaniewicz group revealed that not whole mycobacteria, but Mtb-HSP70, Mtb-HSP 65, and Mtb-HSP16 were detected in the lymph nodes, sera, and precipitated immune complexes in patients with SA and TB. In SA, the Mtb-HSP16 concentration was higher than that of Mtb-HSP70 and that of Mtb-HSP65, whereas in TB, the Mtb-HSP16 level was increased vs. Mtb-HSP70. A high Mtb-HSP16 level, induced by low dose-dependent nitrate/nitrite (NOx), may develop a mycobacterial or propionibacterial genetic dormancy program in SA. In contrast to TB, increased peroxynitrite concentration in supernatants of peripheral blood mononuclear cell cultures treated with Mtb-HSP may explain the low level of NOx detected in SA. In contrast to TB, monocytes in SA were resistant to Mtb-HSP-induced apoptosis, and CD4+T cell apoptosis was increased. Mtb-HSP-induced apoptosis of CD8+T cells was reduced in all tested groups. In Mtb-HSP-stimulated T cells, lower CD8+γδ+IL-4+T cell frequency with increased TNF-α,IL-6,IL-10 and decreased INF-γ,IL-2,IL-4 production were present in SA, as opposed to an increased presence of CD4+γδ+TCR cells with increased TNF-α,IL-6 levels in TB, vs. controls. Mtb-HSP modulating the level of co-stimulatory molecules, regulatory cells, apoptosis, clonal deletion, epitope spread, polyclonal activation and molecular mimicry between human and microbial HSPs may also participate in the induction of autoimmunity, considered in SA. In conclusion, in different genetically predisposed hosts, the same antigens, e.g., Mtb-HSP, may induce the development of TB or SA, including an autoimmune response in sarcoidosis.

Sarcoidosis: Epidemiology and clinical insights

Sarcoidosis is characterized by noncaseating granulomas which form in almost any part of the body, primarily in the lungs and/or thoracic lymph nodes. Environmental exposures in genetically susceptible individuals are believed to cause sarcoidosis. There is variation in incidence and prevalence by region and race. Males and females are almost equally affected, although disease peaks at a later age in females than in males. The heterogeneity of presentation and disease course can make diagnosis and treatment challenging. Diagnosis is suggestive in a patient if one or more of the following is present: radiologic signs of sarcoidosis, evidence of systemic involvement, histologically confirmed noncaseating granulomas, sarcoidosis signs in bronchoalveolar lavage fluid (BALF), and low probability or exclusion of other causes of granulomatous inflammation. No sensitive or specific biomarkers for diagnosis and prognosis exist, but there are several that can be used to support clinical decisions, such as serum angiotensin-converting enzyme levels, human leukocyte antigen types, and CD4 Vα2.3+ T cells in BALF. Corticosteroids remain the mainstay of treatment for symptomatic patients with severely affected or declining organ function. Sarcoidosis is associated with a range of adverse long-term outcomes and complications, and with great variation in prognosis between populations. New data and technologies have moved sarcoidosis research forward, increasing our understanding of the disease. However, there is still much left to be discovered. The pervading challenge is how to account for patient variability. Future studies should focus on how to optimize current tools and develop new approaches so that treatment and follow-up can be targeted to individuals with more precision.

Th17/Treg Imbalance: Implications in Lung Inflammatory Diseases

Regulatory T cells (Tregs) and T helper 17 cells (Th17) are two CD4⁺ T cell subsets with antagonist effects. Th17 cells promote inflammation, whereas Tregs are crucial in maintaining immune homeostasis. Recent studies suggest that Th17 cells and Treg cells are the foremost players in several inflammatory diseases. In this review, we explore the present knowledge on the role of Th17 cells and Treg cells, focusing on lung inflammatory diseases, such as chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), sarcoidosis, asthma, and pulmonary infectious diseases.

An expert overview of pulmonary fibrosis in sarcoidosis

INTRODUCTION

Advanced pulmonary sarcoidosis refers to phenotypes of pulmonary sarcoidosis that often lead to significant loss of lung function, respiratory failure, or death. Around 20% of patients with sarcoidosis may progress to this state which is mainly driven by advanced pulmonary fibrosis. Advanced fibrosis often presents with associated complications of sarcoidosis including infections, bronchiectasis, and pulmonary hypertension.

AREAS COVERED

This article will focus on the pathogenesis, natural history of disease, diagnosis, and potential treatment options of pulmonary fibrosis in sarcoidosis. In the expert opinion section, we will discuss the prognosis and management of patients with significant disease.

EXPERT OPINION

While some patients with pulmonary sarcoidosis remain stable or improve with anti-inflammatory therapies, others develop pulmonary fibrosis and further complications. Although advanced pulmonary fibrosis is the leading cause of death in sarcoidosis, there are no evidence-based guidelines for the management of fibrotic sarcoidosis. Current recommendations are based on expert consensus and often include multidisciplinary discussions with experts in sarcoidosis, pulmonary hypertension, and lung transplantation to facilitate care for such complex patients. Current works evaluating treatments include the use of antifibrotic therapies for treatment in advanced pulmonary sarcoidosis.

In obese hypertensives cholecalciferol inhibits circulating TH17 cells but not macrophage infiltration on adipose tissue

In arterial hypertension, increased Th17 cells and reduced Tregs are the hallmarks of immunological dysfunction and the basis for the investigation of immunomodulatory drugs. Although cholecalciferol is not a primary immunomodulator, it has recognized action on immune cells, leading us to hypothesise if cholecalciferol can induce a more tolerogenic phenotype in obese hypertensives. In a phase-2, single-centre, randomised, open, 24-week trial, we assigned adults with obesity-associated hypertension and vitamin D deficiency to receive usual therapy plus 50,000 IU/week of cholecalciferol or usual therapy alone. The primary endpoint was the percentual variation in T CD4⁺, T CD8⁺, Tregs, and Th17 cells. Secondary endpoints included the percentual variation in Th1, Tc1, Tc17, and monocytes and variation in the number of perivascular and non-perivascular macrophages, T CD4⁺ and T CD8⁺ lymphocytes in subcutaneous abdominal adipose tissue. A control group of 12 overweight normotensives was also evaluated for peripheral immune cells. A total of 36 obese hypertensives were randomised, 18 in each group. In comparison with normotensive controls, hypertensives presented higher percentages of T lymphocytes (p = 0.016), Tregs (p = 0.014), and non-classical monocytes (p < 0.001). At week 24, Th17 cells increased in control group (p = 0.017) but remained stable in cholecalciferol group. For Tregs, downregulation towards the values of normotensive controls was observed (p = 0.003), and in multivariate analysis, an increased loading in the setting of the cells of adaptive immunity observed (eigenvalue 1.78, p < 0.001). No changes were documented for monocytes. In adipose tissue, a baseline negative correlation between vitamin D and perivascular macrophages was observed (r = -0.387, p = 0.024) that persisted in the control group (r = -0.528, p = 0.024) but not in the cholecalciferol group, which presented an increase in non-perivascular macrophages (p = 0.029) at week 24. No serious adverse events were reported for all the participants. In this trial, we found that supplementation with cholecalciferol interfered with peripheral and adipose tissue immune cell profile, downregulating peripheral Th17 cells, but increasing the number of infiltrating subcutaneous adipose tissue macrophages. (Funded by Núcleo Estudos Hipertensão da Beira Interior; EudraCT number: 2015-003910-26).

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.

Cardiac Sarcoidosis: Current Approaches to Diagnosis and Management

PURPOSE OF REVIEW

Cardiac sarcoidosis (CS) is an important cause of non-ischemic cardiomyopathy and has specific diagnostic and therapeutic considerations. With advances in imaging techniques and treatment approaches, the approach to monitoring disease progression and management of CS continues to evolve. The purpose of this review is to highlight advances in CS diagnosis and treatment and present a center's multidisciplinary approach to CS care.

RECENT FINDINGS

In this review, we highlight advances in granuloma biology along with contemporary diagnostic approaches. Moreover, we expand on current targets of immunosuppression focused on granuloma biology and concurrent advances in the cardiovascular care of CS in light of recent guideline recommendations. Here, we review advances in the understanding of the sarcoidosis granuloma along with contemporary diagnostic and therapeutic considerations for CS. Additionally, we highlight knowledge gaps and areas for future research in CS treatment.

Management of Sarcoidosis: When to Treat, How to Treat and for How Long?

Purpose of Review

This review draws together recent publications, consensus statements on sarcoidosis and our 25-year collective experience in managing this disease. We focus on pulmonary sarcoidosis, highlighting recent and established concepts in disease mechanisms, the diversity of the clinical course, including possible ‘subtypes’ of sarcoidosis, and how to measure disease activity. We discuss the principles guiding therapeutic intervention and summarise the more recent clinical trials in sarcoidosis.

Recent Findings

These include recent progress in understanding the mechanisms of disease using new scientific tools, measurements of disease activity using CT and MRI scans, and the potential role of anti-fibrotic treatment for patients with progressive fibrotic sarcoidosis.

Summary

Sarcoidosis is a heterogeneous disease with variable organ involvement, disease course, and response to treatment. We offer an angle on when and how to treat, and provide an overall roadmap for managing sarcoidosis.

Altered transcription factor targeting is associated with differential peripheral blood mononuclear cell proportions in sarcoidosis

Introduction

In sarcoidosis, peripheral lymphopenia and anergy have been associated with increased inflammation and maladaptive immune activity, likely promoting development of chronic and progressive disease. However, the molecular mechanisms that lead to reduced lymphocyte proportions, particularly CD4+ T-cells, have not been fully elucidated. We posit that paradoxical peripheral lymphopenia is characterized by a dysregulated transcriptomic network associated with cell function and fate that results from altered transcription factor targeting activity.

Methods

Messenger RNA-sequencing (mRNA-seq) was performed on peripheral blood mononuclear cells (PBMCs) from ACCESS study subjects with sarcoidosis and matched controls and findings validated on a sarcoidosis case-control cohort and a sarcoidosis case series. Preserved PBMC transcriptomic networks between case-control cohorts were assessed to establish cellular associations with gene modules and define regulatory targeting involved in sarcoidosis immune dysregulation utilizing weighted gene co-expression network analysis and differential transcription factor involvement analysis. Network centrality measures identified master transcriptional regulators of subnetworks related to cell proliferation and death. Predictive models of differential PBMC proportions constructed from ACCESS target gene expression corroborated the relationship between aberrant transcription factor regulatory activity and imputed and clinical PBMC populations in the validation cohorts.

Results

We identified two unique and preserved gene modules significantly associated with sarcoidosis immune dysregulation. Strikingly, increased expression of a monocyte-driven, and not a lymphocyte-driven, gene module related to innate immunity and cell death was the best predictor of peripheral CD4+ T-cell proportions. Within the gene network of this monocyte-driven module, TLE3 and CBX8 were determined to be master regulators of the cell death subnetwork. A core gene signature of differentially over-expressed target genes of TLE3 and CBX8 involved in cellular communication and immune response regulation accurately predicted imputed and clinical monocyte expansion and CD4+ T-cell depletion.

Conclusions

Altered transcriptional regulation associated with aberrant gene expression of a monocyte-driven transcriptional network likely influences lymphocyte function and survival. Although further investigation is warranted, this indicates that crosstalk between hyperactive monocytes and lymphocytes may instigate peripheral lymphopenia and underlie sarcoidosis immune dysregulation and pathogenesis. Future therapies selectively targeting master regulators, or their targets, may mitigate dysregulated immune processes in sarcoidosis and disease progression.

Sarcoidosis: Updates on therapeutic drug trials and novel treatment approaches

Sarcoidosis is a systemic granulomatous inflammatory disease of unknown etiology. It affects the lungs in over 90% of patients yet extra-pulmonary and multi-organ involvement is common. Spontaneous remission of disease occurs commonly, nonetheless, over 50% of patients will require treatment and up to 30% of patients will develop a chronic progressive non-remitting disease with marked pulmonary fibrosis leading to significant morbidity and death. Guidelines outlining an immunosuppressive treatment approach to sarcoidosis were recently published, however, the strength of evidence behind many of the guideline recommended drugs is weak. None of the drugs currently used for the treatment of sarcoidosis have been rigorously studied and prescription of these drugs is often based on off-label” indications informed by experience with other diseases. Indeed, only two medications [prednisone and repository corticotropin (RCI) injection] currently used in the treatment of sarcoidosis are approved by the United States Food and Drug Administration. This situation results in significant reimbursement challenges especially for the more advanced (and often more effective) drugs that are favored for severe and refractory forms of disease causing an over-reliance on corticosteroids known to be associated with significant dose and duration dependent toxicities. This past decade has seen a renewed interest in developing new drugs and exploring novel therapeutic pathways for the treatment of sarcoidosis. Several of these trials are active randomized controlled trials (RCTs) designed to recruit relatively large numbers of patients with a goal to determine the safety, efficacy, and tolerability of these new molecules and therapeutic approaches. While it is an exciting time, it is also necessary to exercise caution. Resources including research dollars and most importantly, patient populations available for trials are limited and thus necessitate that several of the challenges facing drug trials and drug development in sarcoidosis are addressed. This will ensure that currently available resources are judiciously utilized. Our paper reviews the ongoing and anticipated drug trials in sarcoidosis and addresses the challenges facing these and future trials. We also review several recently completed trials and draw lessons that should be applied in future.

Modulatory role of macrophage migration inhibitory factor on cytokines and clinical features of sarcoidosis

Sarcoidosis is a systemic granulomatous disease of unknown etiology with significant heterogeneity in organ manifestations and clinical course. Subjects with sarcoidosis share several features such as, non-necrotizing granuloma, hypergammaglobulinemia, increased local and circulating inflammatory cytokines. Macrophage migration inhibitory factor (MIF) is a pluripotent chemokine modulating cellular function. Study included healthy controls (n = 28) and sarcoidosis patients (n = 65). Sera and BAL of sarcoidosis patients were collected and patients were followed longitudinally for 3 years, and demographics, stages, pulmonary function tests, and organ involvements were recorded. We evaluated MIF in the serum and bronchoalveolar lavage (BAL) fluid of sarcoidosis patients in association with clinical features and cytokines, IL-18, IL-10, IL-6, IFN-γ. We found serum MIF had a positive correlation with IL-10 and IFN-γ and % predicted total lung capacity (%TLC). Serum IL-18 had a significant positive correlation with serum lysozyme, but a negative correlation with %TLC and %DLCO. We identified two groups of sarcoidosis subjects with distinct clinical and cytokine features. A group with prominent extrapulmonary involvement, and low serum MIF, IL-10 and IFN-γ and a group with elevated serum MIF, IL-10 and IFN-γ levels. Our work provides understanding of phenotypic diversity in association with heterogeneity in cytokine landscape in sarcoidosis.

Immune-Checkpoint Expression on CD4, CD8 and NK Cells in Blood, Bronchoalveolar Lavage and Lymph Nodes of Sarcoidosis

Background

Sarcoidosis features non-necrotizing granulomas consisting mainly of activated CD4-lymphocytes. T-cell activation is regulated by immune checkpoint (IC) molecules. The present study aimed to compare IC expression on CD4, CD8 and NK cells from peripheral, alveolar and lung‐draining lymph node (LLN) samples of sarcoidosis patients.

Methods

Flow-cytometry analysis was performed to detect IC molecules and a regression decision tree model was constructed to investigate potential binary classifiers for sarcoidosis diagnosis as well as for the IC distribution.

Results

Fourteen patients (7 females) were consecutively recruited in the study; all enrolled patients showed hilo-mediastinal lymph node enlargement and lung parenchyma involvement with chest X-rays and high resolution computed tomography. CD4+PD1+ and CD8+PD1+ were higher in bronchoalveolar lavage (BAL) than in LLN (p = 0.0159 and p = 0.0439, respectively). CD4+ T-cell immunoglobulin and ITIM domain (TIGIT)+ were higher in BAL than in peripheral blood mononuclear cells (PBMCs) (p = 0.0239), while CD8+TIGIT+ were higher in PBMC than in BAL (p = 0.0386). CD56+TIGIT+ were higher in LLN than in PBMC (p = 0.0126). The decision-tree model showed the best clustering cells of PBMC, BAL and LLN: CD56, CD4/CD8 and CD4+TIGIT+ cells. Considering patients and controls, the best subset was CD4+CTLA-4+.

Conclusion

High expression of PD1 and TIGIT on T cells in BAL, as well as CTLA-4 and TIGIT on T cells in LLN, suggest that inhibition of these molecules could be a therapeutic strategy for avoiding the development of chronic inflammation and tissue damage in sarcoidosis patients.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40291-022-00596-0.

The CSF in neurosarcoidosis contains consistent clonal expansion of CD8 T cells, but not CD4 T cells

The tissue-specific drivers of neurosarcoidosis remain poorly defined. To identify cerebrospinal fluid (CSF) specific, antigen-driven T and B cell responses, we performed single-cell RNA sequencing of CSF and blood cells from neurosarcoid participants coupled to T and B cell receptor sequencing. In contrast to pulmonary sarcoidosis, which is driven by CD4 T cells, we found CD8 T cell clonal expansion enriched in the neurosarcoid CSF. These CSF-enriched CD8 T cells were composed of two subsets with differential expression of EBI2, CXCR3, and CXCR4. Lastly, our data suggest that IFNγ signaling may distinguish neurosarcoidosis from other neurological disorders.

Association Between Sarcoidosis and Risk of Venous Thromboembolism: A Retrospective Chart Review

Introduction

Sarcoidosis is a multisystemic disorder of an unclear etiology. It has been postulated that sarcoidosis is a chronic autoimmune inflammation, which may predispose to venous thromboembolism (VTE). Recent studies showed increased VTE events in patients with sarcoidosis and other autoimmune disorders. This multicenter retrospective study aims at determining a possible correlation between VTE and sarcoidosis.

Subjects and Method

We reviewed charts from a commercial database (Explorys Inc, Cleveland, OH, USA), which is an aggregate of electronic health records from 26 major health care systems. We included patients between 30 and 69 of age. Patients with a condition known to cause a hypercoagulable state were excluded. We calculated the prevalence of VTE in patients with and without a diagnosis of sarcoidosis and compared the results. A multivariate analysis was performed to adjust for gender, race, age, tobacco use, and obesity.

Results

The overall prevalence of the VTE in patients without sarcoidosis was 1.4% compared to 4.9% in patients with sarcoidosis. Patients with sarcoidosis were more likely to develop VTE (OR: 2.96; 95% CI: 2.84-3.08; p < 0.001). Predictors of VTE in patients with sarcoidosis were gender, age, race, and obesity.

Conclusion

Our study indicates that sarcoidosis poses a risk of developing VTE. Further prospective studies are needed to shed light on this association and explain the prothrombotic phenotype of sarcoidosis.

From COVID-19 to Sarcoidosis: How Similar Are These Two Diseases?

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), leads to the dysregulation of the immune system, exacerbates inflammatory responses, and even causes multiple organ dysfunction syndrome in patients with severe disease. Sarcoidosis is an idiopathic granulomatous multisystem disease characterized by dense epithelioid non-necrotizing lesions with varying degrees of lymphocytic inflammation. These two diseases have similar clinical manifestations and may also influence each other and affect their clinical courses. In this study, we analyzed some possible connections between sarcoidosis and COVID-19, including the role of the renin–angiotensin system in the respiratory system, immune response, and cell death pathways, to understand the underlying mechanisms of SARS-CoV-2 infection, predisposing patients to severe forms of COVID-19. This review will provide a new prospect for the treatment of COVID-19 and an opportunity to explore the pathogenesis and development of sarcoidosis.

Central Nervous System Cryptococcosis in Patients With Sarcoidosis: Comparison With Non-sarcoidosis Patients and Review of Potential Pathophysiological Mechanisms

Introduction

Cryptococcus spp. infection of the central nervous system (CINS) is a devastating opportunistic infection that was historically described in patients with acquired immunodeficiency syndrome (AIDS). Cryptococcus spp. infections are also associated with sarcoidosis; the impairment of cell-mediated immunity and long-term corticosteroid therapy being evoked to explain this association. Nevertheless, this assertion is debated and the underlying pathophysiological mechanisms are still unknown. The aims of this study were (i) to describe the clinical and biological presentation, treatments, and outcomes of CINS patients with and without sarcoidosis and (ii) to review the pathophysiological evidence underlying this clinical association.

Patients and Methods

Every patient with positive cerebrospinal fluid (CSF) cryptococcal antigen testing, India ink preparation, and/or culture from January 2015 to December 2020 at a tertiary university hospital were included, and patients with sarcoidosis were compared with non-sarcoidosis patients. Quantitative variables are presented as mean ± SD and are compared using the Mann-Whitney Wilcoxon rank-sum test. Categorical variables are expressed as the number of patients (percentage) and compared using the χ² or Fisher's tests.

Results

During the study period, 16 patients experienced CINS, of whom 5 (31%) were associated with sarcoidosis. CINS symptoms, biological, and CSF features were similar between CINS patients with and without sarcoidosis except regarding CD4 cells percentages and CD4/CD8 ratio that was higher in those with sarcoidosis (47 ± 12 vs. 22 ± 18, p = 0.02 and 2.24 ± 1.42 vs. 0.83 ± 1.10, p = 0.03, respectively). CINS patients with sarcoidosis had less often positive blood antigen testing than those without sarcoidosis (2/5 vs. 11/11, p = 0.02). CINS patients with and without sarcoidosis were treated with similar drugs, but patients with sarcoidosis had a shorter length of treatment. CD4 cell levels do not seem to explain the association between sarcoidosis and cryptococcosis.

Conclusion

Sarcoidosis was the most frequently associated condition with CINS in this study. CINS patients associated with sarcoidosis had overall similar clinical and biological presentation than CINS patients associated with other conditions but exhibited a lower rate of positive blood cryptococcal antigen testing and higher CD4/CD8 T cells ratio. Pathophysiological mechanisms underlying this association remain poorly understood but B-1 cell deficiency or lack of IgM could be a part of the explanation. Another plausible mechanism is the presence of anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibodies in a subset of patients with sarcoidosis, which could impair macrophage phagocytic function. Further studies are strongly needed to better understand those mechanisms and to identify at-risk patients.

Innate and Adaptive Immunity in Noninfectious Granulomatous Lung Disease

Sarcoidosis and chronic beryllium disease are noninfectious lung diseases that are characterized by the presence of noncaseating granulomatous inflammation. Chronic beryllium disease is caused by occupational exposure to beryllium containing particles, whereas the etiology of sarcoidosis is not known. Genetic susceptibility for both diseases is associated with particular MHC class II alleles, and CD4+ T cells are implicated in their pathogenesis. The innate immune system plays a critical role in the initiation of pathogenic CD4+ T cell responses as well as the transition to active lung disease and disease progression. In this review, we highlight recent insights into Ag recognition in chronic beryllium disease and sarcoidosis. In addition, we discuss the current understanding of the dynamic interactions between the innate and adaptive immune systems and their impact on disease pathogenesis.

Atezolizumab-Induced Sarcoidosis-Like Reaction in a Patient with Metastatic Breast Cancer

Tumor-related sarcoidosis-like reactions (SLR) have been reported with the use of immune checkpoint inhibitors (ICIs). We report a case of 50-year-old woman who observed an enlarged lymph node in the right hilar region and the appearance of a subcutaneous mass in the extremities during chemotherapy with atezolizumab plus nab-paclitaxel for metastatic triple-negative breast cancer (TNBC). Skin biopsy revealed the formation of epithelioid granulation species with the Langhans giant cell. After discontinuing atezolizumab in the treatment procedure, the hilar lymph nodes and the subcutaneous mass were reduced. A pathological examination was effective in differentiating tumor exacerbation from SLR. Owing to limited information on ICI-related SLR in breast cancer, future studies are recommended to properly manage immune-related adverse effects during cancer treatment.

Autoantibodies against cytoskeletons and lysosomal trafficking discriminate sarcoidosis from healthy controls, tuberculosis and lung cancers

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Hypergammaglobulinemia and the presence of autoantibodies in sarcoidosis suggest active humoral immunity to unknown antigen(s). We developed a complex cDNA library derived from tissues of sarcoidosis patients. Using a high throughput method, we constructed a microarray platform from this cDNA library containing large numbers of sarcoidosis clones. After selective biopanning, 1070 sarcoidosis-specifc clones were arrayed and immunoscreend with 152 sera from patients with sarcoidosis and other pulmonary diseases. To identify the sarcoidosis classifiers two statistical approaches were conducted: First, we identified significant biomarkers between sarcoidosis and healthy controls, and second identified markers comparing sarcoidosis to all other groups. At the threshold of an False Discovery Rate (FDR) < 0.01, we identified 14 clones in the first approach and 12 clones in the second approach discriminating sarcoidosis from other groups. We used the classifiers to build a naïve Bayes model on the training-set and validated it on an independent test-set. The first approach yielded an AUC of 0.947 using 14 significant clones with a sensitivity of 0.93 and specificity of 0.88, whereas the AUC of the second option was 0.92 with a sensitivity of 0.96 and specificity of 0.83. These results suggest robust classifier performance. Furthermore, we characterized the informative phage clones by sequencing and homology searches. Large numbers of classifier-clones were peptides involved in cellular trafficking and cytoskeletons. These results show that sarcoidosis is associated with a specific pattern of immunoreactivity that can discriminate it from other diseases.

Treating sarcoidosis-associated progressive multifocal leukoencephalopathy with infliximab

Although most of the progressive multifocal leukoencephalopathy cases in sarcoidosis patients are explained by the treatment with immunosuppressive drugs, it is also reported in treatment-naive sarcoidosis patients, which implies a general predisposition of sarcoidosis patients for progressive multifocal leukoencephalopathy. Indeed, it was shown that active sarcoidosis patients have increased regulatory T cell frequencies which could lead to a subsequent systemic immunosuppression. However, if sarcoidosis with systemic changes of T cell subsets frequencies constitute a risk factor for the development of progressive multifocal leukoencephalopathy, which could then be counteracted by sarcoidosis treatment, is not known. In this cohort study, we included, characterized and followed-up six patients with bioptically confirmed definite progressive multifocal leukoencephalopathy and definite or probable sarcoidosis presenting between April 2013 and January 2019, four of them had no immunosuppressive therapy at the time of developing first progressive multifocal leukoencephalopathy symptoms. Analysis of immune cell subsets in these patients revealed significant imbalances of CD4⁺ T cell and regulatory T cell frequencies. Due to the progression of progressive multifocal leukoencephalopathy in four patients, we decided to treat sarcoidosis anticipating normalization of immune cell subset frequencies and thereby improving progressive multifocal leukoencephalopathy. Notably, by treatment with infliximab, an antibody directed against tumour necrosis factor-α, three patients continuously improved clinically, JC virus was no longer detectable in the cerebrospinal fluid and regulatory T cell frequencies decreased. One patient was initially misdiagnosed as neurosarcoidosis and died 9 weeks after treatment initiation due to aspiration pneumonia. Our study provides insight that sarcoidosis can lead to changes in T cell subset frequencies, which predisposes to progressive multifocal leukoencephalopathy. Although immunosuppressive drugs should be avoided in progressive multifocal leukoencephalopathy, paradoxically in patients with sarcoidosis treatment with the immunosuppressive infliximab might restore normal T cell distribution and thereby halt progressive multifocal leukoencephalopathy progression.

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.