Successful therapy with rituximab in three patients with probable neurosarcoidosis

Cerebral vasculitis as a clinical manifestation of neurosarcoidosis: A scoping review

The occurrence of cerebral vasculitis in individuals with neurosarcoidosis (NS) is considered to be rare. Although the number of relevant publications has increased in recent years, evidence is mostly limited to case reports. To obtain a better understanding of this rare and severe manifestation of disease, we carried out a scoping review on cerebral vasculitis in patients diagnosed with NS. The results of the review indicate that the diagnosis of cerebral vasculitis in patients with NS is made especially in patients with systemic sarcoidosis. However, recurrent strokes in patients with NS remains the main indicator of cerebral vasculitis. A tissue biopsy is considered the gold standard to confirm the diagnosis despite occasional false-negative results. Glucocorticoids and steroid-sparing agents are the most successful current treatments. Favorable outcomes were observed with strategies targeting TNFα and B cells. The goal of this review is to summarize the current literature and treatment options for cerebral vasculitis in patients with NS.

Neurosarcoidosis and Neurologic Complications of Sarcoidosis Treatment

Sarcoidosis is an immune-mediated multisystem granulomatous disorder. Neurosarcoidosis (NS) accounts for 5% to 35% of cases. The diagnostic evaluation of NS can be a clinical challenge. Gadolinium-enhanced magnetic resonance imaging (MRI) is the gold standard to evaluate central nervous system NS. In almost all cases treatment is warranted. Although glucocorticoids remain the first-line therapy in patients with sarcoidosis, in NS timely initiation of second- or third-line treatment is strongly recommended. Of these, tumor necrosis factor-alpha inhibitors are the most promising. However, the treatment itself may be responsible for/associated with developing neurologic symptoms mimicking NS. Thus, it is important to consider the possibility of drug-induced neurologic symptoms in sarcoidosis.

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.

Neurosarcoidosis

Sarcoidosis affects the nervous system in 5% of cases. 60% of cases involve the cranial and peripheral nerves, the remainder the central nervous system, in which a leptomeningitis, a pachymeningitis and a vasculitis may arise. Stroke and cerebral haemorrhage may occur, and certain infections in the brain are more likely with sarcoidosis. Patients respond well to treatment but oftentimes with residual neurological impairments which may be severe. A greater understanding of the disease and the need for early treatment and use of biological therapies have improved treatment outcome in recent times.

Quality of life in sarcoidosis

Having sarcoidosis often has a major impact on quality of life of patients and their families. Improving quality of life is prioritized as most important treatment aim by many patients with sarcoidosis, but current evidence and treatment options are limited. In this narrative review, we describe the impact of sarcoidosis on various aspects of daily life, evaluate determinants of health-related quality of life (HRQoL), and provide an overview of the different patient-reported outcome measures to assess HRQoL in sarcoidosis. Moreover, we review the current evidence for pharmacological and non-pharmacological interventions to improve quality of life for people with sarcoidosis.

Tumefactive brain parenchymal neurosarcoidosis

BACKGROUND

Enhancing brain parenchymal disease, and especially tumefactive lesions, are an uncommon manifestation of neurosarcoidosis. Little is known about the clinical features of tumefactive lesions and their impact on management and outcomes, which this study aims to characterize.

METHODS

Patients with pathologically-confirmed sarcoidosis were retrospectively reviewed and included if brain lesions were: (1) intraparenchymal, (2) larger than 1 cm in diameter, and (3) associated with edema and/or mass effect.

RESULTS

Nine patients (9/214, 4.2%) were included. Median onset age was 37 years. Diagnosis was confirmed by brain parenchymal biopsies in 5 (55.6%). Median modified Rankin scale (mRS) score was 2 (range 1-4) at initial presentation. Common manifestations included headache (77.8%), cognitive dysfunction (66.7%), and seizures (44.4%). Sixteen lesions were present in 9 patients. The frontal lobe (31.3%) was most affected, followed by the subinsular region (12.5%), basal ganglia (12.5%%), cerebellum (12.5%), and pons (12.5%). MRI characteristics of the dominant lesions included spherical morphology (77.8%), perilesional edema (100.0%), mass effect (55.6%), well-demarcated borders (66.7%), and contrast enhancement (100.0%; 55.6% heterogeneous). Leptomeningitis was frequently present (77.8%). All required corticosteroid-sparing treatments, and most (55.6%) needed at least a third line of treatment (infliximab used in 44.4%). All patients relapsed (median 3 relapses, range 1-9). Median last mRS was 1.0 after median follow-up of 86 months, with significant residual deficits in 55.6%.

CONCLUSION

Tumefactive brain parenchymal lesions are uncommon, usually affect the supratentorial brain along with leptomeningitis, and are refractory to initial treatments with a high risk of relapse. Significant sequelae were encountered despite a favorable median last mRS.

Management of neurosarcoidosis

This is a brief and purposefully practical approach to the therapeutic and rehabilitative management of patients affected by neurological complications of systemic sarcoidosis. The review notes the drugs used and their monitoring, and their role in the series of clinical subgroups identified to form the condition. Treatment guidelines for individual clinical subtypes of the disorder are provided, and the importance of rehabilitative measures and lifestyle changes are emphasised.

Epidemiology, clinical presentation, treatment, and outcome of neurosarcoidosis: A mono-centric retrospective study and literature review

Introduction

Neurosarcoidosis is a rare granulomatous disorder, and treatment guidelines are mainly based on retrospective studies.

Materials and methods

This retrospective study was performed to provide a detailed description of the clinical characteristics and treatment outcomes of patients with neurosarcoidosis followed at Cliniques Universitaires Saint Luc in Belgium. The second objective of our study was to perform a comparative literature review of neurosarcoidosis, with a focus on treatment outcomes with the use of TNF-α antagonist.

Results

Among 180 patients with sarcoidosis followed in our hospital, 22 patients with neurosarcoidosis were included in the final analysis. Our literature research identified 776 articles of which 35 articles met our inclusion criteria, including 1,793 patients diagnosed with neurosarcoidosis. In our cohort, the majority of patients (86%) were diagnosed with systemic sarcoidosis which was similar to that reported in the literature (83%). Serum CRP and calcemia were elevated only in 33 and 18% of patients, respectively. Serum lysozyme and angiotensin-converting enzyme were elevated in 79 and 16% of patients, respectively. Lumbar puncture and CSF fluid analysis were performed in 15/22 patients and were abnormal in all patients. Brain MRI was performed in 21/22 patients and showed abnormalities in 16 patients consisting of parenchymal lesions in 63%, hypothalamic-pituitary axis lesions in 38%, and meningeal enhancement in 31%. In both cohort patients, methotrexate was the most frequently used treatment (>45% of cases) with a favorable outcome in an average of 50% of patients. A TNF-α antagonist was administered in 9% of patients in our cohort and in 27% of patients in the literature review. The proportion of favorable outcomes in literature research was significantly higher in patients treated with TNF-α antagonists compared to methotrexate (p < 0.0001), mycophenolate mofetil (p < 0.0001), or azathioprine (p < 0.0001).

Conclusion

The results of our cohort and literature review confirm that neurosarcoidosis occurred most frequently in the context of systemic sarcoidosis. Methotrexate is the most frequent second-line therapy. The effectiveness of therapy with TNF-α antagonists is well-demonstrated and associated with a better outcome. Their earlier use during the disease course among aggressive and/or refractory neurosarcoidosis should be considered.

A Rare Case of Neurosarcoidosis Overlapped with Sjogren’s Syndrome

The coexisting of sarcoidosis and Sjögren’s syndrome (SS) has long been neglected since sarcoidosis is considered as an exclusion criterion for SS. We described a 55-year-old woman, who was diagnosed with coexisting neurosarcoidosis and Sjögren’s syndrome for 16 years. She presented with erythema nodosum, progressive sensory and motor impairment of the extremities, dry mouth, and dry eyes. High-resolution computed tomography (HRCT) of the chest showed symmetrical pulmonary micronodules, interstitial changes, and enlarged mediastinal lymph nodes. Spine magnetic resonance imaging (MRI) showed syringomyelia and thickening of the T3-9 spinal cord. She was with positive ANA and anti-SSA antibodies, impaired function of the lacrimal, salivary gland and renal tubules. Biopsy of skin and lung nodules revealed non-caseous granuloma. Salivary gland biopsy showed focal lymphocyte infiltration. Classification criteria for sarcoidosis and Sjogren’s syndrome were fulfilled in this patient based on clinical and laboratory features. This case extends our understanding of overlapped Sjogren’s syndrome with sarcoidosis and provides a referential value for clinical diagnosis.

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 Center Experience with Isolated Spinal Cord Neurosarcoidosis

INTRODUCTION

Isolated spinal cord neurosarcoidosis is extremely rare. The potential implications of long-term immunosuppressant therapy make correct diagnosis imperative. However, there are challenges inherent in isolated spinal cord involvement that require a multidisciplinary approach. Here we present the largest series of definite and possible isolated spinal neurosarcoidosis and discuss our institutional experience in managing this rare but morbid condition.

METHODS

A retrospective review was performed to identify all neurosarcoidosis cases starting from 2002 to 2020 at our institution. Patients were screened for cases of isolated spinal neurosarcoidosis. A descriptive analysis was performed for each case.

RESULTS

A total of 64 cases of neurosarcoidosis were identified. The spine was involved in 26 (40.6%) patients. Only 4 (6.3%) cases had isolated spinal cord involvement. A full medical and imaging workup was performed in determining isolated spinal cord involvement. Three patients subsequently underwent surgical biopsy, and 1 did not undergo biopsy because of patient preference. One of the patients who underwent biopsy had an initial nondiagnostic biopsy and had a repeat biopsy. Corticosteroids were employed in all cases with additional immunosuppressive agents for maintenance therapy and refractory cases. All showed radiographic improvement and were clinically stable to improved.

CONCLUSION

Isolated spinal cord involvement of neurosarcoidosis is rare and can present challenges in diagnosis. A biopsy can be performed when necessary. However, a biopsy of the spinal cord carries inherent risks and may not always be possible or result in a nondiagnostic sample. In the setting of high clinical suspicion, maximal medical therapy is still employed.

Rituximab for the Treatment of Refractory Cardiac Sarcoidosis-A Single Center Experience

OBJECTIVE

To examine the effect of anti-B cell therapy (rituximab) on cardiac inflammation and function in corticosteroid-refractory cardiac sarcoidosis.

BACKGROUND

Cardiac sarcoidosis (CS) is a rare cause of cardiomyopathy characterized by granulomatous inflammation involving the myocardium. While typically responsive to corticosteroid treatment, there is a critical need for identifying effective steroid-sparing agents for disease control. Despite growing evidence on the role of B-cells in the pathogenesis of sarcoidosis, there is limited data on the efficacy of anti-B cell therapy, specifically rituximab, for controlling CS.

METHODS

We reviewed the clinical experience at a tertiary care referral center of all patients with CS who received rituximab after failing to improve with initial immunosuppression therapy, which included corticosteroids. Fluorodeoxyglucose positron emission tomography (FDG-PET/CT) images before and after rituximab treatment were evaluated. All images were interpreted by 2 experienced nuclear medicine trained physicians.

RESULTS

We identified seven patients, (5 men, 2 women; mean age at diagnosis, 49.0±7.9 years) with active cardiac sarcoidosis who were treated with rituximab. The median length of follow-up was 5.1 years. All individuals, but 1, had received prior steroid-sparing agents in addition to corticosteroids. Rituximab was administered either as 1000 mg IV x 1 or x 2 doses, separated by 2 weeks. Repeat dosing, if appropriate, was considered after 6 months. All tolerated the infusions well.Inflammation as assessed by maximum SUV on cardiac FDG PET/CT uptake significantly decreased in 6 of 7 patients (median 6.0 to 4.5, Wilcoxon signed rank z: -1.8593, W: 3), whereas left ventricular ejection fraction improved or stabilized in 4 patients but decreased in 3. Mean left ventricular ejection fraction (LVEF) was 40.1% and 43.3% before and after treatment respectively (p=0.28). Three patients reported improved physical capacity, and 5 patients showed improved arrhythmic burden on Holter monitoring or ICD interrogation. One patient subsequently developed fungal catheter-associated infection and sepsis requiring discontinuation.

CONCLUSIONS

Rituximab was well tolerated and appeared to decrease inflammation, as assessed by cardiac FDG PET/CT scan, in all but 1 patient with active CS. These data suggest that rituximab may be a promising therapeutic option for CS, which deserves further study.

Autoimmune Neurogenic Dysphagia

Autoimmune neurogenic dysphagia refers to manifestation of dysphagia due to autoimmune diseases affecting muscle, neuromuscular junction, nerves, roots, brainstem, or cortex. Dysphagia is either part of the evolving clinical symptomatology of an underlying neurological autoimmunity or occurs as a sole manifestation, acutely or insidiously. This opinion article reviews the autoimmune neurological causes of dysphagia, highlights clinical clues and laboratory testing that facilitate early diagnosis, especially when dysphagia is the presenting symptom, and outlines the most effective immunotherapeutic approaches. Dysphagia is common in inflammatory myopathies, most prominently in inclusion body myositis, and is frequent in myasthenia gravis, occurring early in bulbar-onset disease or during the course of progressive, generalized disease. Acute-onset dysphagia is often seen in Guillain–Barre syndrome variants and slowly progressive dysphagia in paraneoplastic neuropathies highlighted by the presence of specific autoantibodies. The most common causes of CNS autoimmune dysphagia are demyelinating and inflammatory lesions in the brainstem, occurring in patients with multiple sclerosis and neuromyelitis optica spectrum disorders. Less common, but often overlooked, is dysphagia in stiff-person syndrome especially in conjunction with cerebellar ataxia and high anti-GAD autoantibodies, and in gastrointestinal dysmotility syndromes associated with autoantibodies against the ganglionic acetyl-choline receptor. In the setting of many neurological autoimmunities, acute-onset or progressive dysphagia is a potentially treatable condition, requiring increased awareness for prompt diagnosis and early immunotherapy initiation.

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.

Key Players and Biomarkers of the Adaptive Immune System in the Pathogenesis of Sarcoidosis

Sarcoidosis is a systemic inflammatory disease characterized by development of granulomas in the affected organs. Sarcoidosis is often a diagnosis of exclusion, and traditionally used tests for sarcoidosis demonstrate low sensitivity and specificity. We propose that accuracy of diagnosis can be improved if biomarkers of altered lymphocyte populations and levels of signaling molecules involved in disease pathogenesis are measured for patterns suggestive of sarcoidosis. These distinctive biomarkers can also be used to determine disease progression, predict prognosis, and make treatment decisions. Many subsets of T lymphocytes, including CD8⁺ T-cells and regulatory T-cells, have been shown to be dysfunctional in sarcoidosis, and the predominant CD4⁺ T helper cell subset in granulomas appears to be a strong indicator of disease phenotype and outcome. Studies of altered B cell populations, B cell signaling molecules, and immune complexes in sarcoidosis patients reveal promising biomarkers as well as possible explanations of disease etiology. Furthermore, examined biomarkers raise questions about new treatment methods and sarcoidosis antigens.

Is neuromyelitis optica without AQP4-IgG a T-cell mediated disease? insights from checkpoint inhibitor immune-related adverse events

A 30-year-old female presented with recurrent opticospinal demyelinating attacks after introduction of nivolumab to treat Hodgkin's lymphoma. Paraneoplastic, neuronal surface, and demyelinating antibodies were negative from the serum and/or cerebrospinal fluid. Oligoclonal bands were negative and she met clinical criteria for NMOSD without AQP4-IgG. She could not tolerate plasmapheresis due to transfusion-related acute lung injury but responded well to corticosteroids and discontinuation of nivolumab. The precipitation of typical NMOSD without AQP4-IgG syndrome by a checkpoint inhibitor suggests a possible T-cell mediated pathogenesis. This may help explain why this patient group lacked response to B-cell therapies in NMOSD clinical trials.

Indications for treatment of sarcoidosis

PURPOSE OF REVIEW

To describe the current knowledge on indications for sarcoidosis treatment.

RECENT FINDINGS

Despite the lack of evidence-based recommendations, the sarcoidosis community has adopted the concept of starting systemic anti-inflammatory treatment because of potential danger (risk of severe dysfunction on major organs or death) or unacceptable impaired quality of life (QoL). On the contrary, while QoL and functionality are patients' priorities, few studies have evaluated treatment effect on patient-reported outcomes. The awareness of long-term corticosteroids toxicities and consequences on QoL and the emergence of novel drugs have changed therapeutic management. Second-line therapy, mainly methotrexate and azathioprine, are indicated for corticosteroids sparing or corticosteroids-resistant sarcoidosis. TNF-α inhibitors are a useful third-line therapy in chronic refractory disease. In addition to organ-targeted treatment, efforts should also be taken for treating nonorgan-specific symptoms, such as physical training for fatigue, and various disease complications.

SUMMARY

Clinicians should offer a tailored treatment for each patient and ensure a holistic multidisciplinary approach, including pharmacological and nonpharmacological interventions. Patient-centered communication is critical to drive shared decisions, in particular for the tricky situation of isolated impaired QoL as the unique therapeutic indication. Once treatment is decided, clinicians should define a clear therapeutic plan, including goals and instruments to assess response.

Neurosarcoidosis: clinical manifestations, investigation and treatment

Sarcoidosis affects the nervous system in 10% of cases. When it does so it can affect any part of the nervous system and with all degrees of severity. It forms part of the differential diagnosis in inflammatory, infective, neoplastic and degenerative neurological diseases and may be very difficult to diagnose without histological confirmation. Recent clinical studies and the increasing availability of new biological treatments allow a much clearer understanding of the disease. This review summarises its clinical features, imaging and laboratory characteristics, treatment and outcome.

Refractory Sarcoidosis: A Review

Sarcoidosis is a multi-system disease of unknown etiology characterized by granuloma formation in various organs (especially lung and mediastinohilar lymph nodes). In more than half of patients, the disease resolves spontaneously. When indicated, it usually responds to corticosteroids, the first-line treatment, but some patients may not respond or tolerate them. An absence of treatment response is rare and urges for verifying the absence of a diagnosis error, the good adherence of the treatment, the presence of active lesions susceptible to respond since fibrotic lesions are irreversible. That is when second-line treatments, immunosuppressants (methotrexate, leflunomide, azathioprine, mycophenolate mofetil, hydroxychloroquine), should be considered. Methotrexate is the only first-line immunosuppressant validated by a randomized controlled trial. Refractory sarcoidosis is not yet a well-defined condition, but it remains a real challenge for the physicians. Herein, we considered refractory sarcoidosis as a disease in which second-line treatments are not sufficient to achieve satisfying disease control or satisfying corticosteroids tapering. Tumor necrosis alpha inhibitors, third-line treatments, have been validated through randomized controlled trials. There are currently no guidelines or recommendations regarding refractory sarcoidosis. Moreover, criteria defining non-response to treatment need to be clearly specified. The delay to achieve response to organ involvement and drugs also should be defined. In the past ten years, the efficacy of several immunosuppressants beforehand used in other autoimmune or inflammatory diseases was reported in refractory cases series. Among them, anti-CD20 antibodies (rituximab), repository corticotrophin injection, and anti-JAK therapy anti-interleukin-6 receptor monoclonal antibody (tocilizumab) were the main reported. Unfortunately, no clinical trial is available to validate their use in the case of sarcoidosis. Currently, other immunosuppressants such as JAK inhibitors are on trial to assess their efficacy in sarcoidosis. In this review, we propose to summarize the state of the art regarding the use of immunosuppressants and their management in the case of refractory or multidrug-resistant sarcoidosis.

Delphi consensus recommendations for a treatment algorithm in pulmonary sarcoidosis

Pulmonary sarcoidosis presents substantial management challenges, with limited evidence on effective therapies and phenotypes. In the absence of definitive evidence, expert consensus can supply clinically useful guidance in medicine. An international panel of 26 experts participated in a Delphi process to identify consensus on pharmacological management in sarcoidosis with the development of preliminary recommendations.

The modified Delphi process used three rounds. The first round focused on qualitative data collection with open-ended questions to ensure comprehensive inclusion of expert concepts. Rounds 2 and 3 applied quantitative assessments using an 11-point Likert scale to identify consensus.

Key consensus points included glucocorticoids as initial therapy for most patients, with non-biologics (immunomodulators), usually methotrexate, considered in severe or extrapulmonary disease requiring prolonged treatment, or as a steroid-sparing intervention in cases with high risk of steroid toxicity. Biologic therapies might be considered as additive therapy if non-biologics are insufficiently effective or are not tolerated with initial biologic therapy, usually with a tumour necrosis factor-α inhibitor, typically infliximab.

The Delphi methodology provided a platform to gain potentially valuable insight and interim guidance while awaiting evidenced-based contributions.

Expert consensus recommendations for a pulmonary sarcoidosis treatment algorithm from a modified Delphi process include corticosteroids as initial therapy, immunomodulators for steroid-sparing or severe disease, and biologics for very severe diseasehttp://bit.ly/2SmP3uG

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.