Fine mapping of chromosome 15q25 implicates ZNF592 in neurosarcoidosis patients

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.

Genetic predisposition to sarcoidosis

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

Genetics of neurosarcoidosis

Sarcoidosis is a systemic, inflammatory, granulomatous disease characterized by great variability in organ involvement, clinical course, and severity. While pulmonary manifestations are almost universal, the central and peripheral nervous systems can also be affected. Neurosarcoidosis occurs in ∼5-15% of cases and is among the manifestations with the highest morbidity and mortality. It is known that sarcoidosis has genetic underpinnings and while multiple studies aimed at identifying associations to sarcoidosis susceptibility and prognosis, very few studies have focused on neurosarcoidosis. This review summarizes the genetic studies to date, compares and contrasts those findings with other genetic effects in sarcoidosis, and offers ideas for moving the field forward.

Offense and Defense in Granulomatous Inflammation Disease

Granulomatous inflammation (GI) diseases are a group of chronic inflammation disorders characterized by focal collections of multinucleated giant cells, epithelioid cells and macrophages, with or without necrosis. GI diseases are closely related to microbes, especially virulent intracellular bacterial infections are important factors in the progression of these diseases. They employ a range of strategies to survive the stresses imposed upon them and persist in host cells, becoming the initiator of the fighting. Microbe-host communication is essential to maintain functions of a healthy host, so defense capacity of hosts is another influence factor, which is thought to combine to determine the result of the fighting. With the development of gene research technology, many human genetic loci were identified to be involved in GI diseases susceptibility, providing more insights into and knowledge about GI diseases. The current review aims to provide an update on the most recent progress in the identification and characterization of bacteria in GI diseases in a variety of organ systems and clinical conditions, and examine the invasion and escape mechanisms of pathogens that have been demonstrated in previous studies, we also review the existing data on the predictive factors of the host, mainly on genetic findings. These strategies may improve our understanding of the mechanisms underlying GI diseases, and open new avenues for the study of the associated conditions in the future.

Genome-Wide Association Study of Ocular Sarcoidosis Confirms HLA Associations and Implicates Barrier Function and Autoimmunity in African Americans

Purpose: Identify genes associated with ocular sarcoidosis (OS).Methods: We genotyped 1.1 million genetic variants to identify significant OS associations, defined as those that achieved p < 5 × 10-8 in a genome-wide comparison of OS cases to healthy controls in our European- or African-American cohorts (EA, AA). Potential functional roles of all associated variants were assessed.Results: Eight significant non-HLA variants were found in AA OS cases compared to healthy controls and confirmed as at least suggestive when comparing OS to non-OS cases. Seven of these were within MAGI1 and include transcription factor binding sites and expression quantitative trait loci. Our EA cohort, while showing similar effect sizes at variants within MAGI1, had no significant variants. Association analysis of HLA-DRB1 alleles confirmed association to OS in EA to *04:01.Conclusion: Our results support organ-specific genetic risk in OS in a compelling candidate, MAGI1, known to be associated with barrier function and autoimmunity.

Recent advances in sarcoidosis genomics: epigenetics, gene expression, and gene by environment (G × E) interaction studies

PURPOSE OF REVIEW

We aim to review the most recent findings in genomics of sarcoidosis and highlight the gaps in the field.

RECENT FINDINGS

Original explorations of sarcoidosis subphenotypes, including cases associated with the World Trade Center and ocular sarcoidosis, have identified novel risk loci. Innovative gene--environment interaction studies utilizing modern analytical techniques have discovered risk loci associated with smoking and insecticide exposure. The application of whole-exome sequencing has identified genetic variants associated with persistent sarcoidosis and rare functional variations. A single epigenomics study has provided background knowledge of DNA methylation mechanisms in comparison with gene expression data. The application of machine-learning techniques has suggested new drug repositioning for the treatment of sarcoidosis. Several gene expression studies have identified prominent inflammatory pathways enriched in the affected tissue.

SUMMARY

Certainly, sarcoidosis research has recently advanced in the exploration of disease subphenotypes, utilizing novel analytical techniques, and including measures of clinical variation. Nevertheless, large-scale and diverse cohorts investigated with advanced sequencing methods, such as whole-genome and single-cell RNA sequencing, epigenomics, and meta-analysis coupled with cutting-edge analytic approaches, when employed, will broaden and translate genomics findings into clinical applications, and ultimately open venues for personalized medicine.

Current Insights in Genetics of Sarcoidosis: Functional and Clinical Impacts

Sarcoidosis is a complex disease that belongs to the vast group of autoinflammatory disorders, but the etiological mechanisms of which are not known. At the crosstalk of environmental, infectious, and genetic factors, sarcoidosis is a multifactorial disease that requires a multidisciplinary approach for which genetic research, in particular, next generation sequencing (NGS) tools, has made it possible to identify new pathways and propose mechanistic hypotheses. Codified treatments for the disease cannot always respond to the most progressive forms and the identification of new genetic and metabolic tracks is a challenge for the future management of the most severe patients. Here, we review the current knowledge regarding the genes identified by both genome wide association studies (GWAS) and whole exome sequencing (WES), as well the connection of these pathways with the current research on sarcoidosis immune-related disorders.

Clinical and MRI phenotypes of sarcoidosis-associated myelopathy

OBJECTIVE

To determine the characteristic clinical and spinal MRI phenotypes of sarcoidosis-associated myelopathy (SAM), we analyzed a large cohort of patients with this disorder.

METHODS

Patients 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.

RESULTS

Of 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).

CONCLUSIONS

Recognition 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.

High-Risk Sarcoidosis. Current Concepts and Research Imperatives

Sarcoidosis is a disease with heterogeneous manifestations and outcomes, varying in part on the basis of organ involvement. Specifically, patients with sarcoidosis at risk for poor outcomes include individuals with treatment-resistant pulmonary sarcoidosis, including fibrotic pulmonary disease and pulmonary hypertension, as well as those with cardiac, neurologic, and multiorgan disease. The limited but available data relating to these patients with high-risk sarcoidosis, defined as those patients with presentations requiring medical intervention to avoid progressive disability or premature death, was evaluated as part of the National Heart, Lung, and Blood Institute's workshop to improve understanding of these disease manifestations. In particular, knowledge gaps that preclude a greater understanding of the pathogenesis and management of these severe sarcoidosis clinical phenotypes were identified in the workshop. Research strategies are proposed to address critical knowledge gaps that would further our understanding of these disease manifestations and enhance the care of these patients.

Genetic, Immunologic, and Environmental Basis of Sarcoidosis

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.

Polygenic risk assessment reveals pleiotropy between sarcoidosis and inflammatory disorders in the context of genetic ancestry

Sarcoidosis is a complex disease of unknown etiology characterized by the presence of granulomatous inflammation. Though various immune system pathways have been implicated in disease, the relationship between the genetic determinants of sarcoidosis and other inflammatory disorders has not been characterized. Herein, we examined the degree of genetic pleiotropy common to sarcoidosis and other inflammatory disorders to identify shared pathways and disease systems pertinent to sarcoidosis onset. To achieve this, we quantify the association of common variant polygenic risk scores from nine complex inflammatory disorders with sarcoidosis risk. Enrichment analyses of genes implicated in pleiotropic associations were further used to elucidate candidate pathways. In European-Americans, we identify significant pleiotropy between risk of sarcoidosis and risk of asthma (R²=2.03%; p=8.89×10⁻⁹), celiac disease (R²=2.03%; p=8.21×10⁻⁹), primary biliary cirrhosis (R²=2.43%; p=2.01×10⁻¹⁰), and rheumatoid arthritis (R²=4.32%; p=2.50×10⁻¹⁷). These associations validate in African Americans only after accounting for the proportion of genome-wide European ancestry, where we demonstrate similar effects of polygenic risk for African-Americans with the highest levels of European ancestry. Variants and genes implicated in European-American pleiotropic associations were enriched for pathways involving interleukin-12, interleukin-27, and cell adhesion molecules, corroborating the hypothesized immunopathogenesis of disease.