Etiology of sarcoidosis.

Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
Clinics in Chest Medicine (Impact Factor: 2.17). 10/2008; 29(3):365-77, vii. DOI: 10.1016/j.ccm.2008.03.011
Source: PubMed

ABSTRACT Research over the past decade has advanced our understanding of the pathogenesis of sarcoidosis and provided new insights into potential causes of this disease. It is important to remember that any etiologic agent of sarcoidosis must be capable of causing the pathologic hallmark of systemic noncaseating granulomas and the heterogeneous clinical features of sarcoidosis. In addition, etiologic agents must be compatible with immunologic features, including polarized T-helper 1 cytokine profiles and oligoclonal T cell expansions consistent with antigen driven processes. Yet, even with studies conducted in this disease, there remains a lack of consensus on the etiology of sarcoidosis. This challenge is likely to be overcome only with additional research that incorporates clinical, genetic, immunologic, environmental, and microbiologic profiles in groups of patients, supplemented with testing of candidate pathogenic agents in experimental models that recapitulate critical features of this disease.

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    ABSTRACT: Sarcoidosis is a chronic systemic disease of unknown etiology that is characterized by the presence of noncaseating epithelioid granulomas, usually in multiple organs. Several studies have shown that sarcoidosis might be the result of an exaggerated granulomatous reaction after exposure to unidentified antigens in genetically susceptible individuals. Cardiac involvement may occur and lead to an adverse outcome: the heart mechanics will be affected and that causes ventricular failure, and the cardiac electrical system will be disrupted and lead to third degree atrioventricular block, malignant ventricular tachycardia, and sudden cardiac death. Thus, early diagnosis and treatment of this potentially devastating disease is critically important. However, sensitive and accurate imaging modalities have not been established. Recent studies have demonstrated the promising potential of cardiac magnetic resonance imaging (MRI) and (18)F-fluoro-2-deoxyglucose positron emission tomography ((18)F-FDG PET) in the diagnosis and assessment of cardiac sarcoidosis (CS). In this review, we discuss the epidemiology, etiology, histological findings, and clinical features of sarcoidosis. We also introduce advanced imaging including (18)F-FDG PET and cardiac MRI as more reliable diagnostic modalities for CS.
    BioMed Research International 01/2014; 2014:897956. · 2.71 Impact Factor
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    ABSTRACT: Introduction. Sarcoidosis is a chronic granulomatous disease, which can involve different organs and systems. Coexistence of sarcoidosis and spondyloarthritis has been reported in numerous case reports. Purpose. To determine the prevalence of sacroiliitis and spondyloarthritis in patients previously diagnosed with sarcoidosis and to investigate any possible relation with clinical findings. Materials and Methods. Forty-two patients with sarcoidosis were enrolled in the study. Any signs and symptoms in regard to spondyloarthritis (i.e., existence of inflammatory back pain, gluteal pain, uveitis, enthesitis, dactylitis, inflammatory bowel disease, and psoriasis) were questioned in detail and biochemical tests were evaluated. Sacroiliac joint imaging and lateral heel imaging were performed in all patients. Results. Sacroiliitis was found in 6 of the 42 (14.3%) sarcoidosis patients and all of these patients were female. Common features of the disease in these six patients were inflammatory back pain as the major clinical complaint, stage 2 sacroiliitis as revealed by radiological staging, and the negativity of HLA B-27 test. These six patients with sacroiliitis were diagnosed with spondyloarthritis according to the criteria of ASAS and of ESSG. Conclusion. We found spondyloarthritis in patients with sarcoidosis at a higher percentage rate than in the general population (1-1.9%). Controlled trials involving large series of patients are required for the confirmation of the data.
    International journal of rheumatology. 01/2014; 2014:289454.
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    ABSTRACT: Sarcoidosis is a granulomatous inflammatory disease that is induced by unknown antigen(s) in a genetically susceptible host. Although the direct link between Mycobacterium tuberculosis (MTB) infection and sarcoidosis can be excluded on the basis of current knowledge, non-infectious mechanisms may explain the causative role of mycobacterial antigens. Ever since sarcoidosis was first described, its relationship with tuberculosis (TB) has been under-investigated. Whereas some researchers consider sarcoidosis and TB as two examples of the same disease process, others have rejected mycobacteria as playing any causative role in sarcoidosis. Whether they are linked causally or not, clinical evidence makes a differential diagnosis between the two conditions very challenging, particularly in countries with high burden of TB. The present study analyzes the relationship between sarcoidosis and TB and its implications in clinical practice. The coincidence of TB and sarcoidosis and the higher incidence of mycobacterial DNA in biological samples of sarcoid patients have been reported by many authors. In addition, new evidence of a similarity in MTB phenotype in sarcoidosis is provided. Overall, these observations suggest that TB and sarcoidosis may not only share the same etiology, but may even be different aspects of one disease.
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Edward S Chen