Search

Sarcoidosis is a multisystem granulomatous disease of unknown origin with a variable and often unpredictable course and pattern of organ involvement. In this study we sought to identify specific bronchoalveolar lavage (BAL) cell gene expression patterns indicative of distinct disease phenotypic traits.RNA sequencing by Ion Torrent Proton was performed on BAL cells obtained from 215 well characterized patients with pulmonary sarcoidosis enrolled in the multicenter Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis (GRADS) study. Weighted Gene Co-expression Network Analysis (WGCNA) and non-parametric statistics were used to analyze genome wide BAL transcriptome. Validation of results was performed using a microarray expression data set of an independent sarcoidosis cohort (Freiburg, Germany (n=50)).Our supervised analysis found associations between distinct transcriptional programs and major pulmonary phenotypic manifestations of sarcoidosis including; TH1 and TH17 pathways associated with hilar lymphadenopathy; TGFB1 and MTOR signaling with parenchymal involvement, and IL7 and IL2 with airway involvement. Our unsupervised analysis revealed gene modules that uncovered four potential sarcoidosis endotypes including hilar lymphadenopathy with increased acute T cell immune response; extraocular organ involvement with PI3K activation pathways; chronic and multiorgan disease with increased immune response pathways; and multiorgan with increased IL-1 and IL-18 immune and inflammatory responses. We validated the occurrence of these endotypes using gene expression, pulmonary function tests and cell differentials from Freiburg. Taken together our results identify BAL gene expression programs that characterize major pulmonary sarcoidosis phenotypes and suggest the presence of distinct disease molecular endotypes.Take home messageGenome wide BAL transcriptomics identified novel gene expression profiles associated with distinct phenotypic traits in sarcoidosis and is suggestive of the presence of novel molecular and clinical sarcoidosis endotypes that could help with further understanding of this heterogenous disease.

Importance The Neurosarcoidosis Consortium Consensus Group, an expert panel of physicians experienced in the management of patients with sarcoidosis and neurosarcoidosis, engaged in an iterative process to define neurosarcoidosis and develop a practical diagnostic approach to patients with suspected neurosarcoidosis. This panel aimed to develop a consensus clinical definition of neurosarcoidosis to enhance the clinical care of patients with suspected neurosarcoidosis and to encourage standardization of research initiatives that address this disease. Observations The work of this collaboration included a review of the manifestations of neurosarcoidosis and the establishment of an approach to the diagnosis of this disorder. The proposed consensus diagnostic criteria, which reflect current knowledge, provide definitions for possible, probable, and definite central and peripheral nervous system sarcoidosis. The definitions emphasize the need to evaluate patients with findings suggestive of neurosarcoidosis for alternate causal factors, including infection and malignant neoplasm. Also emphasized is the need for biopsy, whenever feasible and advisable according to clinical context and affected anatomy, of nonneural tissue to document the presence of systemic sarcoidosis and support a diagnosis of probable neurosarcoidosis or of neural tissue to support a diagnosis of definite neurosarcoidosis. Conclusions and Relevance Diverse disease presentations and lack of specificity of relevant diagnostic tests contribute to diagnostic uncertainty. This uncertainty is compounded by the absence of a pathognomonic histologic tissue examination. The diagnostic criteria we propose are designed to focus investigations on NS as accurately as possible, recognizing that multiple pathophysiologic pathways may lead to the clinical manifestations we currently term NS. Research recognizing the clinical heterogeneity of this diagnosis may open the door to identifying meaningful biologic factors that may ultimately contribute to better treatments.

Sarcoidosis is a multisystem disease with tremendous heterogeneity in disease manifestations, severity, and clinical course that varies among different ethnic and racial groups. To better understand this disease and to improve the outcomes of patients, a National Heart, Lung, and Blood Institute workshop was convened to assess the current state of knowledge, gaps, and research needs across the clinical, genetic, environmental, and immunologic arenas. We also explored to what extent the interplay of the genetic, environmental, and immunologic factors could explain the different phenotypes and outcomes of patients with sarcoidosis, including the chronic phenotypes that have the greatest healthcare burden. The potential use of current genetic, epigenetic, and immunologic tools along with study approaches that integrate environmental exposures and precise clinical phenotyping were also explored. Finally, we made expert panel-based consensus recommendations for research approaches and priorities to improve our understanding of the effect of these factors on the health outcomes in sarcoidosis.

Sarcoidosis is a disorder of unknown etiology. It is a systemic disease, frequently involving the lungs, skin, eyes, and lymph nodes. It is characterized by formation of noncaseating granulomas at the site(s) of disease. Sarcoidosis has a complex disease pathogenesis, with involvement of both the innate and adaptive immune systems. Several innate immune system receptors including NOD-like receptors and Toll-like receptors appear to be involved in the development of sarcoidosis as well as cellular players such as dendritic cells and macrophages. Furthermore, lymphocytes from the adaptive immune system including Th1, Th17, regulatory T cells, and B cells are likely to play a role in the sarcoidosis disease pathogenesis as well. Possibly, genetic susceptibility and exposure to particular etiologic agents including mycobacterial and propionibacterial antigens, metals, and silica can cause sarcoidosis. Besides exogenous triggers, also self-compounds such as serum amyloid A and vimentin, have been found to play a role in the development of sarcoidosis. It is likely that sarcoidosis does not have one single cause but rather is the result of the interplay between different etiologic agents and the immune system in predisposed individuals.

BACKGROUND: Sarcoidosis, one of the most common interstitial lung diseases, has significant health disparities. Approximately 50% of individuals affected with sarcoidosis will undergo spontaneous remission, but those who do not undergo remission often require long-term or lifelong treatment to prevent disease progression. We sought to assess the association between medication adherence and clinical outcomes in sarcoidosis. METHODS: Adult patients in the Johns Hopkins Sarcoidosis Clinic diagnosed with pulmonary sarcoidosis on treatment were eligible for enrollment. Questionnaires were administered to assess medication adherence, health-related quality of life (HRQoL), health-care utilization, and sociodemographic information. Clinical information was abstracted from medical charts including lung function, disease duration, comorbidities, and sarcoidosis organ involvement. RESULTS: A total of 117 participants were enrolled (57% women; 55% black; median age, 57 years). Within the cohort, 66% of individuals reported at least one nonadherent behavior. Higher medication adherence was associated with better HRQoL (P

In the originally published version of Figure 2, a figure permissions line was omitted in error. The correct figure permission line has now been added to the HTML and PDF versions of the article, stating “Adapted from ref.46, CC-BY-4.0 https://creativecommons.org/licenses/ by/4.0/.”. In addition, a typographical error in reference 46 has been corrected.

Sarcoidosis is an inflammatory disorder of unknown cause that is characterized by granuloma formation in affected organs, most often in the lungs. Patients frequently suffer from cough, shortness of breath, chest pain and pronounced fatigue and are at risk of developing lung fibrosis or irreversible damage to other organs. The disease develops in genetically predisposed individuals with exposure to an as-yet unknown antigen. Genetic factors affect not only the risk of developing sarcoidosis but also the disease course, which is highly variable and difficult to predict. The typical T cell accumulation, local T cell immune response and granuloma formation in the lungs indicate that the inflammatory response in sarcoidosis is induced by specific antigens, possibly including self-antigens, which is consistent with an autoimmune involvement. Diagnosis can be challenging for clinicians because of the potential for almost any organ to be affected. As the aetiology of sarcoidosis is unknown, no specific treatment and no pathognomic markers exist. Thus, improved biomarkers to determine disease activity and to identify patients at risk of developing fibrosis are needed. Corticosteroids still constitute the first-line treatment, but new treatment strategies, including those targeting quality-of-life issues, are being evaluated and should yield appropriate, personalized and more effective treatments.

ObjectiveTo determine the characteristic clinical and spinal MRI phenotypes of sarcoidosis-associated myelopathy (SAM), we analyzed a large cohort of patients with this disorder.MethodsPatients diagnosed with SAM at a single center between 2000 and 2018 who met the established criteria for definite and probable neurosarcoidosis were included in a retrospective analysis to identify clinical profiles, CSF characteristics, and MRI lesion morphology.ResultsOf 62 included patients, 33 (53%) were male, and 30 (48%) were African American. SAM was the first clinical presentation of sarcoidosis in 49 patients (79%). Temporal profile of symptom evolution was chronic in 81%, with sensory symptoms most frequently reported (87%). CSF studies showed pleocytosis in 79% and CSF-restricted oligoclonal bands in 23% of samples tested. Four discrete patterns of lesion morphology were identified on spine MRI: longitudinally extensive myelitis (n = 28, 45%), short tumefactive myelitis (n = 14, 23%), spinal meningitis/meningoradiculitis (n = 14, 23%), and anterior myelitis associated with areas of disc degeneration (n = 6, 10%). Postgadolinium enhancement was seen in all but 1 patient during the acute phase. The most frequent enhancement pattern was dorsal subpial enhancement (n = 40), followed by meningeal/radicular enhancement (n = 23) and ventral subpial enhancement (n = 12). In 26 cases (42%), enhancement occurred at locations with coexisting structural changes (e.g., spondylosis).ConclusionsRecognition of the clinical features (chronically evolving myelopathy) and distinct MRI phenotypes (with enhancement in a subpial and/or meningeal pattern) seen in SAM can aid diagnosis of this disorder. Enhancement patterns suggest that SAM may have a predilection for areas of the spinal cord susceptible to mechanical stress.

Since sarcoidosis was first described more than a century ago, the etiologic determinants causing this disease remain uncertain. Studies suggest that genetic, host immunologic, and environmental factors interact together to cause sarcoidosis. Immunologic characteristics of sarcoidosis include non-caseating granulomas, enhanced local expression of T helper-1 (and often Th17) cytokines and chemokines, dysfunctional regulatory T-cell responses, dysregulated Toll-like receptor signaling, and oligoclonal expansion of CD4+ T cells consistent with chronic antigenic stimulation. Multiple environmental agents have been suggested to cause sarcoidosis. Studies from several groups implicate mycobacterial or propionibacterial organisms in the etiology of sarcoidosis based on tissue analyses and immunologic responses in sarcoidosis patients. Despite these studies, there is no consensus on the nature of a microbial pathogenesis of sarcoidosis. Some groups postulate sarcoidosis is caused by an active viable replicating infection while other groups contend there is no clinical, pathologic, or microbiologic evidence for such a pathogenic mechanism. The authors posit a novel hypothesis that proposes that sarcoidosis is triggered by a hyperimmune Th1 response to pathogenic microbial and tissue antigens associated with the aberrant aggregation of serum amyloid A within granulomas, which promotes progressive chronic granulomatous inflammation in the absence of ongoing infection.

Introduction: We analyzed the transcriptome of bronchoalveolar lavage cells (BAL) in a large cohort of well characterized sarcoidosis subjects by RNA-sequencing to better understand disease progression and severity, and potentially identify novel molecular phenotypes. Methods: BAL was performed on subjects enrolled in the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis study (GRADS) as described (Moller et al., Ann Am Thorac Soc, 2015 PMID: 26193069). cDNA libraries were prepared from 1ug of RNA and sequenced by Ion Torrent Proton Sequencer. Cufflinks calculated Fragments per Kilobase of exon per Million (FPKM) values. Non-parametric correlation methods and Metacore identified significant genes and pathways. Weighted gene co-expression network analysis (WGCNA) revealed correlation networks between gene expression and clinical traits. Multiple hypothesis testing was controlled at FDR Results: 199 samples from 24 stage I, 33 stage II-III treated, 40 stage II-III untreated, 17 stage IV treated, and 12 stage IV untreated subjects were available (53.2% females, 23.1% blacks). Correlation analysis revealed that 65 genes were increased with advanced Scadding stage and 24 were decreased (FDR Conclusion: RNA-sequencing of BAL in sarcoidosis patients identified novel genes associated with features of disease. Preliminary analysis suggests the presence of molecular disease endotypes.

A consensus statement found in most peer-reviewed literature on sarcoidosis is that the etiology of sarcoidosis is unknown. It is timely to review whether this statement should be revised. Many infectious agents meet the basic requirements of inducing granulomatous inflammation and immunologic responses consistent with sarcoidosis including oligoclonal expansion of CD4+ T cells, polarized Th1 and possibly Th17 responses, and dysregulated regulatory T-cell function. Studies over the past decade provide increasing and complementary data to implicate a role for infectious agents in sarcoidosis etiology. These studies used different methodologies such as polymerase chain reaction and mass spectrometry to document microbial nucleic acids and proteins in sarcoidosis tissues. Multiple studies report antigen-specific immune responses to specific microbial proteins in sarcoidosis. In aggregate, these studies provide compelling evidence that mycobacteria play a major etiologic role in sarcoidosis in the United States and Europe. Studies from Japan support a role for Propionibacteria as a major etiologic agent in the country. There is controversy over how these (or other) infectious agents cause sarcoidosis. The hypothesis that chronic sarcoidosis is caused by a viable, replicating mycobacterial or other infection has no direct pathologic, microbiologic, or clinical evidence. A novel hypothesis links microbial triggers to a sarcoidosis outcome from the accumulation of aggregated proinflammatory serum amyloid A within granulomas, providing a mechanism for chronic disease in the absence of any viable tissue infection. Further studies are needed to provide more definitive evidence for these competing hypotheses before the statement that the etiology of sarcoidosis is unknown becomes obsolete.

Objectives This study sought to evaluate the effects of inflammatory sarcoid disease on coronary circulatory function and the response to immune-suppressive treatment. Background Although positron emission tomography assessment of myocardial inflammation is increasingly applied to identify active cardiac sarcoidosis, its effect on coronary flow and immune-suppressive treatment remains to be characterized. Methods Thirty-two individuals, who were referred for positron emission tomography/computed tomography, were evaluated for known or suspected cardiac sarcoidosis applying 18 F-fluorodeoxyglucose to determine inflammation and 13 N-ammonia to assess for perfusion deficits following a high-fat/low-carbohydrate diet and fasting state >12 h to suppress myocardial glucose uptake. Inflammation was quantified with standardized uptake value and regional myocardial blood flow at rest and during regadenoson-stimulated hyperemia was determined in ml/g/min. Positron emission tomography studies were repeated in 18 cases with a median follow-up of 2.5 years (interquartile range [IQR]:1.3 to 3.4 years). Results Twenty-five exams had normal perfusion but evidence of regional inflammation (group 1), and 21 exams presented a regional perfusion deficit associated with inflammation (group 2). Median myocardial blood flow did not differ between inflamed and noninflamed myocardium in both groups (0.86 ml/g/min [IQR: 0.66 to 1.11 ml/g/min] vs. 0.83 ml/g/min [IQR: 0.64 to 1.12 ml/g/min] and 0.74 ml/g/min [IQR: 0.60 to 0.93 ml/g/min] vs. 0.77 ml/g/min [IQR: 0.59 to 0.95 ml/g/min], respectively). As regards median hyperemic myocardial blood flows, they were significantly lower in the inflamed than in the remote regions in group 1 and 2 (2.31 ml/g/min [IQR: 1.81 to 2.95 ml/g/min] vs. 2.70 ml/g/min [IQR: 2.07 to 3.30 ml/g/min] and 1.61 ml/g/min [IQR: 1.17 to 2.18 ml/g/min] vs. 1.94 ml/g/min [IQR: 1.49 to 2.39 ml/g/min]; p 4.1) and ΔMFR (r = –0.47; p = 0.048). Conclusions Sarcoid-mediated myocardial inflammation is associated with a regional impairment of coronary circulatory function. The association between immune-suppressive treatment-related alterations in myocardial inflammation and changes in coronary vasodilator capacity suggests direct adverse effect of inflammation on coronary circulatory function in cardiac sarcoidosis.

Background Pulmonary hypertension (PH) is a common complication of sarcoidosis that is associated with increased mortality. The pathogenesis of PH in sarcoidosis is uncertain, and the role of pulmonary arterial hypertension (PAH)-specific therapies remains to be determined. Methods We conducted a retrospective study of patients with sarcoidosis and PH at two referral centers. New York Heart Association (NYHA) functional class, exercise capacity, hemodynamic data, pulmonary function tests, and survival were collected and analyzed. Results Twenty-two sarcoidosis patients treated with PAH-specific therapies were identified. After a median of 11 months of follow-up, NYHA class was improved in nine subjects. Mean 6-min walk distance (n = 18) increased by 59 m (p = 0.032). Patients with a higher FVC experienced a greater increment in exercise capacity. Among 12 patients with follow-up hemodynamic data, mean pulmonary artery pressure was reduced from 48.5 ± 4.3 to 39.4 ± 2.8 mm Hg (p = 0.008). The 1- and 3-year transplant-free survival rates were 90% and 74%, respectively. Conclusions PAH-specific therapy may improve functional class, exercise capacity, and hemodynamics in PH associated with sarcoidosis. Prospective, controlled trials of PAH therapies for sarcoidosis are warranted to verify this apparent benefit. Mortality among the study population was high, highlighting the need for urgent evaluation at a lung transplant center.

Sarcoidosis is a systemic granulomatous disease associated with local epithelioid granulomas, CD4+ T cells, and Th1 cytokines. The tissue Ags that drive this granulomatous inflammation are uncertain. In this study, we used IFN-γ-ELISPOT assays and flow cytometry to assess lung and blood T cell responses to the candidate pathogenic Ag, Mycobacterium tuberculosis catalase-peroxidase (mKatG) in patients with sarcoidosis from two centers. Despite differences in patient phenotypic, genetic, and prognostic characteristics, we report that T cell responses to mKatG were remarkably similar in these cohorts, with higher frequencies of mKatG-reactive, IFN-γ-expressing T cells in the blood of sarcoidosis patients compared with nontuberculosis sensitized healthy controls, and (in a subset) in greater numbers than T cells reactive to purified protein derivative. In sarcoidosis, mKatG-reactive CD4+ Th1 cells preferentially accumulated in the lung, indicating a compartmentalized response. Patients with or without Löfgren syndrome had similar frequencies of mKatG specific IFN-γ-expressing blood T cells. Circulating mKatG-reactive T cells were found in chronic active sarcoidosis but not in patients with inactive disease. Together, these results demonstrate that T cell responses to mKatG in sarcoidosis fit a profile expected for a pathogenic Ag, supporting an immunotherapeutic approach to this disease.

Acquisition of T cell responses during primary CMV infection in lung transplant recipients (LTRs) appear critical for host defense and allograft durability, with increased mortality in donor+/recipient− (D+R−) individuals. In 15 D+R− LTRs studied, acute primary CMV infection was characterized by viremia in the presence or absence of pneumonitis, with viral loads higher in the lung airways/allograft compared with the blood. A striking influx of CD8+ T cells into the lung airways/allograft was observed, with inversion of the CD4+:CD8+ T cell ratio. De novo CMV-specific CD8+ effector frequencies in response to pooled peptides of pp65 were strikingly higher in lung mononuclear cells compared with the PBMC and predominated over IE1-specific responses and CD4+ effector responses in both compartments. The frequencies of pp65-specific cytokine responses were significantly higher in lung mononuclear cells compared with PBMC and demonstrated marked contraction with long-term persistence of effector memory CD8+ T cells in the lung airways following primary infection. CMV-tetramer+CD8+ T cells from PBMC were CD45RA− during viremia and transitioned to CD45RA+ following resolution. In contrast, CMV-specific CD8+ effectors in the lung airways/allograft maintained a CD45RA− phenotype during transition from acute into chronic infection. Together, these data reveal differential CMV-specific CD8+ effector frequencies, immunodominance, and polyfunctional cytokine responses predominating in the lung airways/allograft compared with the blood during acute primary infection. Moreover, we show intercompartmental phenotypic differences in CMV-specific memory responses during the transition to chronic infection.

The etiology of sarcoidosis remains uncertain. The hallmark of sarcoidosis is the epithelioid granuloma, which serves as a necessary starting point for considering disease etiology. Any etiologic agent of sarcoidosis must also explain the typical clinical behaviors and characteristic immunopathologic features of the disease. One clinical observation that serves as a bridge to the etiology of sarcoidosis is the Kveim reaction. In this reaction, local epithelioid granulomas develop several weeks after the intradermal injection of homogenates of sarcoidosis tissue. Our group capitalized on the known properties of the Kveim reagent to search for candidate pathogenic tissue antigens in sarcoidosis without other a priori hypotheses regarding possible microbial or autoimmune etiologies. Using a limited proteomics approach based on the physicochemical properties of Kveim reagent, we detected a limited number of poorly soluble antigenic proteins in sarcoidosis tissues by protein immunoblotting, using sarcoidosis sera. Matrix-associated laser desorption/ionization-time of flight mass spectrometry identified one of these antigens to be the Mycobacterium tuberculosis catalase-peroxidase protein (mKatG). We found IgG responses to recombinant mKatG in more than 50% of patients with sarcoidosis but rarely in purified protein derivative (PPD)-negative control subjects. These findings support the conclusion that mKatG is a tissue antigen and target of the adaptive immune response in sarcoidosis, providing further evidence of a mycobacterial etiology in a subset of sarcoidosis. More generally, the approach used in these studies might be employed to discover and validate other candidate pathogenic antigens in sarcoidosis or other granulomatous disorders.

Granulomatous lung diseases, such as sarcoidosis, hypersensitivity pneumonitis, Wegener's granulomatosis, and chronic beryllium disease, along with granulomatous diseases of known infectious etiologies, such as tuberculosis, are major causes of morbidity and mortality throughout the world. Clinical manifestations of these diseases are highly heterogeneous, and the determinants of disease susceptibility and clinical course (e.g., resolution vs. chronic, progressive fibrosis) are largely unknown. The underlying pathogenic mechanisms of these diseases also remain poorly understood. Within this context, these diseases have been approached using genomic and proteomic technologies to allow us to identify patterns of gene/protein expression that track with clinical disease or to identify new pathways involved in disease pathogenesis. The results from these initial studies highlight the potential for these “-omics” approaches to reveal novel insights into the pathogenesis of granulomatous lung disease and provide new tools to improve diagnosis, clinical classification, course prediction, and response to therapy. Realizing this potential will require collaboration among multidisciplinary groups with expertise in the respective technologies, bioinformatics, and clinical medicine for these complex diseases.

Sarcoidosis is a systemic disease characterized by noncaseating granulomatous inflammation with tremendous clinical heterogeneity and uncertain pathobiology and lacking in clinically useful biomarkers. The Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis (GRADS) study is an observational cohort study designed to explore the role of the lung microbiome and genome in these two diseases. This article describes the design and rationale for the GRADS study sarcoidosis protocol. The study addresses the hypothesis that distinct patterns in the lung microbiome are characteristic of sarcoidosis phenotypes and are reflected in changes in systemic inflammatory responses as measured by peripheral blood changes in gene transcription. The goal is to enroll 400 participants, with a minimum of 35 in each of 9 clinical phenotype subgroups prioritized by their clinical relevance to understanding of the pathobiology and clinical heterogeneity of sarcoidosis. Participants with a confirmed diagnosis of sarcoidosis undergo a baseline visit with self-administered questionnaires, chest computed tomography, pulmonary function tests, and blood and urine testing. A research or clinical bronchoscopy with a research bronchoalveolar lavage will be performed to obtain samples for genomic and microbiome analyses. Comparisons will be made by blood genomic analysis and with clinical phenotypic variables. A 6-month follow-up visit is planned to assess each participant’s clinical course. By the use of an integrative approach to the analysis of the microbiome and genome in selected clinical phenotypes, the GRADS study is powerfully positioned to inform and direct studies on the pathobiology of sarcoidosis, identify diagnostic or prognostic biomarkers, and provide novel molecular phenotypes that could lead to improved personalized approaches to therapy for sarcoidosis.

Sarcoidosis, a systemic granulomatous disease of unknown etiology, likely results from an environmental insult in a genetically susceptible host. In the US, African Americans are more commonly affected with sarcoidosis and suffer greater morbidity than Caucasians. We searched for sarcoidosis susceptibility loci by conducting a genome-wide, sib pair multipoint linkage analysis in 229 African-American families ascertained through two or more sibs with a history of sarcoidosis. Using the Haseman-Elston regression technique, linkage peaks with P-values less than 0.05 were identified on chromosomes 1p22, 2p25, 5p15-13, 5q11, 5q35, 9q34, 11p15 and 20q13 with the most prominent peak at D5S2500 on chromosome 5q11 (P=0.0005). We found agreement for linkage with the previously reported genome scan of a German population at chromosomes 1p and 9q. Based on the multiple suggestive regions for linkage found in our study population, it is likely that more than one gene influences sarcoidosis susceptibility in African Americans. Fine mapping of the linked regions, particularly on chromosome 5q, should help to refine linkage signals and guide further sarcoidosis candidate gene investigation.

Sarcoidosis is a disease of unknown etiology characterized by noncaseating epithelioid granulomas, oligoclonal CD4+ T cell infiltrates, and immune complex formation. To identify pathogenic antigens relevant to immune-mediated granulomatous inflammation in sarcoidosis, we used a limited proteomics approach to detect tissue antigens that were poorly soluble in neutral detergent and resistant to protease digestion, consistent with the known biochemical properties of granuloma-inducing sarcoidosis tissue extracts. Tissue antigens with these characteristics were detected with immunoglobulin (Ig)G or F(ab′)2 fragments from the sera of sarcoidosis patients in 9 of 12 (75%) sarcoidosis tissues (150–160, 80, or 60–64 kD) but only 3 of 22 (14%) control tissues (all 62–64 kD; P = 0.0006). Matrix-assisted laser desorption/ionization time of flight mass spectrometry identified Mycobacterium tuberculosis catalase–peroxidase (mKatG) as one of these tissue antigens. Protein immunoblotting using anti-mKatG monoclonal antibodies independently confirmed the presence of mKatG in 5 of 9 (55%) sarcoidosis tissues but in none of 14 control tissues (P = 0.0037). IgG antibodies to recombinant mKatG were detected in the sera of 12 of 25 (48%) sarcoidosis patients compared with 0 of 11 (0%) purified protein derivative (PPD)− (P = 0.0059) and 4 of 10 (40%) PPD+ (P = 0.7233) control subjects, suggesting that remnant mycobacterial catalase–peroxidase is one target of the adaptive immune response driving granulomatous inflammation in sarcoidosis.

To determine whether specific occupations and industries may be associated with sarcoidosis.A Case Control Etiologic Study of Sarcoidosis (ACCESS) obtained occupational and environmental histories on 706 newly diagnosed sarcoidosis cases and matched controls. We used Standard Industrial Classification (SIC) and Standard Occupational Classification (SOC) to assess occupational contributions to sarcoidosis risk.Univariable analysis identified elevated risk of sarcoidosis for workers with industrial organic dust exposures, especially in Caucasian workers. Workers for suppliers of building materials, hardware, and gardening materials were at an increased risk of sarcoidosis as were educators. Work providing childcare was negatively associated with sarcoidosis risk. Jobs with metal dust or metal fume exposures were negatively associated with sarcoidosis risk, especially in Caucasian workers.In this study, we found that exposures in particular occupational settings may contribute to sarcoidosis risk.

Past research suggests that environmental factors may be associated with sarcoidosis risk. We conducted a case control study to test a priori hypotheses that environmental and occupational exposures are associated with sarcoidosis. Ten centers recruited 706 newly diagnosed patients with sarcoidosis and an equal number of age-, race-, and sex-matched control subjects. Interviewers administered questionnaires containing questions regarding occupational and nonoccupational exposures that we assessed in univariable and multivariable analyses. We observed positive associations between sarcoidosis and specific occupations (e.g., agricultural employment, odds ratio [OR] 1.46, confidence interval [CI] 1.13-1.89), exposures (e.g., insecticides at work, OR 1.52, CI 1.14-2.04, and work environments with mold/mildew exposures [environments with possible exposures to microbial bioaerosols], OR 1.61, CI 1.13-2.31). A history of ever smoking cigarettes was less frequent among cases than control subjects (OR 0.62, CI 0.50-0.77). In multivariable modeling, we observed elevated ORs for work in areas with musty odors (OR 1.62, CI 1.24-2.11) and with occupational exposure to insecticides (OR 1.61, CI 1.13-2.28), and a decreased OR related to ever smoking cigarettes (OR 0.65, CI 0.51-0.82). The study did not identify a single, predominant cause of sarcoidosis. We identified several exposures associated with sarcoidosis risk, including insecticides, agricultural employment, and microbial bioaerosols.

Progress in our understanding of the scientific basis of granulomatous inflammation in sarcoidosis provides a framework for enlightened treatment decisions. Current evidence supports the concept that the pathogenesis of sarcoidosis involves a highly polarized T-helper 1 (Th1) immune response to pathogenic tissue antigens. Conventional treatment is focused on attenuating granuloma formation with antimalarial drugs that inhibit antigen presentation or with nonspecific anti-inflammatory agents such as glucocorticosteroids, methotrexate, or azathioprine. Anti-tumour necrosis factor (TNF)-alpha agents such as pentoxifylline, thalidomide, etanercept and remicade, have recently shown some successes in sarcoidosis. Designing future therapies depends on improved knowledge of the critical immunological processes operative in different stages of disease.

Limited but encouraging progress has been made over the last several years in our understanding of the etiology of sarcoidosis as a result of recent investments in epidemiologic, immunologic, and molecular biologic studies. A recent US multicenter study of sarcoidosis found few environmental or occupational exposures associated with a two-fold or higher risk of development of sarcoidosis, suggesting noninfectious exposures play a small, if any, role in causing systemic sarcoidosis. In contrast, recent studies have linked infectious agents including mycobacterial and propionibacterial organisms with sarcoidosis. The association of sarcoidosis with the use of Th1-promoting biologic response modifiers is consistent with a central role for enhanced Th1 immune responses in the pathogenesis of sarcoidosis. Given evidence for a genetic predisposition to sarcoidosis, these findings suggest that the etiology of systemic sarcoidosis is linked to genetically determined enhanced Th1 immune responses to a limited number of microbial pathogens.

Study objectives Thalidomide therapy has been shown to modify granulomatous diseases, such as tuberculosis and leprosy. Lupus pernio is a skin manifestation of sarcoidosis that does not remit spontaneously, and was used as a marker of efficacy of thalidomide for sarcoidosis. Design An open-label, dose-escalation trial of thalidomide. Setting Patients were seen at one of four specialized sarcoidosis clinics in the United States. Patients Fifteen patients with lupus pernio and other manifestations of sarcoidosis unresponsive to prior therapy were enrolled. Interventions Skin lesions were assessed with visual examination by the treating physician, and photographic evaluation by a blinded panel of physicians reviewing photographs of the lesions before and after therapy. Measurements and results Fourteen patients completed 4 months of therapy. All patients experienced some improvement in their skin lesions subjectively, and 10 of 12 evaluable patients showed improvement using photograph scoring. Five patients were better after 1 month (treated with 50 mg/d of thalidomide), seven more patients improved after 2 months (treated with 100 mg/d of thalidomide in the second month), and two patients required an additional month of 200 mg of thalidomide to achieve a response. Patients reported increased somnolence (n = 9), numbness (n = 7), dizziness (n = 2), constipation (n = 6), rash (n = 1), and increasing shortness of breath (n = 1). One patient discontinued therapy because of new-onset dyspnea, due to probably unrelated new-onset congestive heart failure. Conclusion Thalidomide was an effective form of treatment for chronic cutaneous sarcoidosis. The drug was well tolerated and may be a useful alternative to systemic corticosteroids.

In this issue of the European Respiratory Journal , Judson et al. [1] report the results of a large clinical trial involving two new potential therapies in sarcoidosis, a subcutaneous anti-tumour necrosis factor (TNF) agent, golimumab, and a novel anti-p40 (a component of both interleukin (IL)-12 and IL-23) agent, ustekinumab. The rationale for the use of anti-TNF agents in sarcoidosis is compelling, as TNF plays a central role in granuloma formation [2]. The use of anti-p40 (anti-IL-12/IL-23) also has a solid rationale based on the role of IL-12 in promoting T-helper (Th) type 1 immune responses and its upregulation in sarcoidosis. The role of the IL-23/Th17 pathways in sarcoidosis is less well established but the benefits of blocking IL-23 together with IL-12 is conceptually appealing in sarcoidosis [3]. Given the clear rationale for testing these therapies in sarcoidosis, it is disappointing that neither therapy showed clinical benefit assessed by either primary or secondary end-points. These negative results follow a large trial of infliximab by many of these same investigators. In a randomised, placebo-controlled trial of infliximab in pulmonary sarcoidosis by Baughman et al. [4], there was a statistically significant 2.5% increase in forced vital capacity (FVC) % predicted with infliximab versus placebo and no significant differences for any of the major secondary end-points at 6 months. Although the authors suggest this was a robust response, healthcare payers (both corporations and governments) concluded that infliximab demonstrated only minimal improvement for patients with pulmonary sarcoidosis and cite this research as a reason to deny coverage of this therapy. Several studies find infliximab beneficial for progressive nonpulmonary manifestations of sarcoidosis [5, 6], but in aggregate, these studies have not led to regulatory approval for infliximab in sarcoidosis in either Europe …

Summary Sarcoidosis is a granulomatous disorder of unknown aetiology. The presence of Mycobacterium tuberculosis catalase-peroxidase (mKatG) in sarcoidosis tissue has been reported. T helper type 1 (Th1) responses against mKatG have previously been observed. However, little is known about interleukin (IL)-17 and Th17 responses in sarcoidosis. Here, we investigated the levels of IL-17 and frequencies of IL-17-producing cells responding to mKatG in sarcoidosis patients with different prognosis. Peripheral blood and bronchoalveolar lavage (BAL) cells were obtained from sarcoidosis patients with or without Löfgren's syndrome (often associated with spontaneous recovery), and also stratified according to human leucocyte antigen (HLA) type. Cells producing IL-17 and interferon (IFN)-γ after stimulation with mKatG were enumerated by enzyme-linked immunospot (ELISPOT). The level of IL-17 in the BAL fluid of sarcoidosis patients and healthy controls was measured by quantitative immuno-polymerase chain reaction (qIPCR). We also performed flow cytometry and immunohistochemistry for further characterization of IL-17 expression. Patients with Löfgren's syndrome had a higher frequency of IL-17-producing cells responding to mKatG in BAL fluid compared to patients without Löfgren's syndrome (P < 0·05). The HLA-DR3+ sarcoidosis patients with Löfgren's syndrome (known to have a particularly good prognosis) also had a clearly higher level of IL-17 in BAL fluid compared to healthy controls and sarcoidosis patients without Löfgren's syndrome (P < 0·01) and (P < 0·05), respectively. No such difference between patient groups was observed with regard to IFN-γ and not with regard to either cytokine in peripheral blood. These findings suggest that IL-17-producing cells may be a useful biomarker for the prognosis of sarcoidosis and play a role in the spontaneous recovery typical of patients with Löfgren's syndrome.

Because mouse strains susceptible to bleomycin, such as C57BL/ 6J, tend to produce T helper type 1 (Th1) cytokines in response to immune activation, we hypothesized that the inflammatory response to bleomycin is mediated, in part, by local production of the Th1 cytokine interferon-gamma (IFN-gamma). Consistent with this hypothesis, fibrosis-prone C57BL/6J and A/J mice demonstrated significantly elevated expression of IFN-gamma protein (by enzyme-linked immunosorbent assay) in bronchoalveolar lavage fluid at 24 h, and subsequently increased lung inflammation, weight loss, and mortality 10 d after intratracheal bleomycin administration compared with fibrosis-resistant BALB/c mice or saline control mice. To directly determine a role for IFN-gamma in bleomycin toxicity, we exposed C57BL/6J mice with a homozygous null mutation of the IFN-gamma gene (IFN-gamma[-/-]) and wild-type C57BL/6J mice to intratracheal bleomycin. IFN-gamma(-/-) mice demonstrated significantly lower parenchymal inflammation, weight loss, and mortality 10 d after 5 U/kg intratracheal bleomycin administration compared with control mice. At 3 wk after 1.5 U/kg bleomycin exposure, single lung collagen determined by hydroxyproline assay was significantly lower in IFN-gamma(-/-) mice compared with wild-type C57BL/6J mice. Together, these results suggest that IFN-gamma mediates, in part, bleomycin-induced pulmonary inflammation and fibrosis.

Sarcoidosis is a granulomatous disease of unknown aetiology, mainly affecting the lungs. Recently, T-cell responses towards a specific mycobacterial protein, catalase-peroxidase (mKatG), were observed in sarcoidosis patients. Bronchoalveolar lavage (BAL) fluid and peripheral blood were obtained from a total of 23 sarcoidosis patients, of whom 13 had Lofgren's syndrome and lung accumulations of T-cell receptor AV2S3+ T-cells. Using six-colour flow cytometry in combination with intracellular cytokine staining, T-cell subsets were studied with regard to interferon (IFN)-γ, tumour necrosis factor (TNF) and interleukin-2 production, after stimulation with mKatG or Mycobacterium tuberculosis purified protein derivate (PPD). Stimulation with mKatG resulted in higher simultaneous IFN-γ and TNF production, but less single IFN-γ production, from total BAL fluid CD4+ T-cells of Lofgren's syndrome patients, when compared with non-Lofgren's patients. In contrast, PPD stimulation gave rise to largely similar cytokine responses in both patient subgroups. Furthermore, mKatG stimulated higher IFN-γ production in BAL fluid and blood AV2S3+ T-cells than AV2S3- T-cells, whereas the opposite was seen in BAL fluid with PPD stimulation. Our finding that patients with Lofgren's syndrome exhibited a more pronounced multifunctional cytokine profile (simultaneous IFN-γ and TNF production) towards the mycobacterial protein mKatG may help to explain the distinct disease presentation in this patient subgroup.

Sarcoidosis is an uncommon systemic inflammatory disorder characterized by noncaseating granulomatous inflammation that most commonly affects the lungs, intrathoracic lymph nodes, eyes and skin. One-third or more of patients with sarcoidosis have chronic, unremitting inflammation with progressive organ impairment. Findings of family and genetic studies indicate a genetic susceptibility to sarcoidosis, with genes in the MHC region having a dominant role. Immunologic hallmarks of the disease include highly polarized expression of cytokines produced by type 1 T helper cells and tumor necrosis factor (TNF) at sites of inflammation. Increasing evidence obtained within the past decade suggests the etiology of sarcoidosis predominantly involves microbial triggers, with the most convincing data implicating mycobacterial or propionibacterial organisms. Innate immune mechanisms, possibly involving misfolding and aggregation of serum amyloid A, might have a critical role in the pathobiology of sarcoidosis. Despite these advances, there are no clinically useful biomarkers that can assist the clinician in diagnosis, prognosis or assessment of treatment effects. Corticosteroids remain the cornerstone of therapy when organ function is threatened or progressively impaired. The role of immunosuppressive drugs and anti-TNF agents in the treatment of sarcoidosis remains uncertain, and there are no FDA-approved therapies. Meaningful progress in developing clinically useful tools and new therapies will depend on further advances in understanding the pathogenesis of sarcoidosis and its disease-specific pathways.

BACKGROUND: Both type I interferon (IFN), also known as IFN-α and tumor necrosis factor alpha (TNF-α) have been implicated in the pathogenesis of sarcoidosis. We investigated serum levels of these cytokines in a large multi-ancestral sarcoidosis population to determine correlations between cytokine levels and disease phenotypes. METHODS: We studied serum samples from 98 patients with sarcoidosis, including 71 patients of African-American ancestry and 27 patients of European-American ancestry. Serum type I IFN was measured using a sensitive reporter cell assay and serum TNF-α was measured using a commercial ELISA kit. Clinical data including presence or absence of neurologic, cardiac, and severe pulmonary manifestations of sarcoidosis were abstracted from medical records. Twenty age-matched non-autoimmune controls were also studied from each ancestral background. Differences in cytokine levels between groups were analyzed with Mann-Whitney U test, and correlations were assessed using Spearman's rho. Multivariate logistic regression models were used to detect associations between cytokines and clinical manifestations. RESULTS: Significant differences in cytokine levels were observed between African- and European-American patients with sarcoidosis. In African-Americans, serum TNF-α levels were significantly higher relative to matched controls (P = 0.039), and patients with neurologic disease had significantly higher TNF-α than patients lacking this manifestation (P = 0.022). In European-Americans, serum type I IFN activity was higher in sarcoidosis cases as compared to matched controls, and patients with extra-pulmonary disease represented a high serum IFN subgroup (P = 0.0032). None of the associations observed were shared between the two ancestral groups. CONCLUSIONS: Our data indicate that significant associations between serum levels of TNF-α and type I IFN and clinical manifestations exist in a sarcoidosis cohort that differ significantly by self-reported ancestry. In each ancestral background, the cytokine elevated in patients with sarcoidosis was also associated with a particular disease phenotype. These findings may relate to ancestral differences in the molecular pathogenesis of this heterogeneous disease.