Fine-mapping in African-American women confirms the importance of the 10p12 locus to sarcoidosis

Genome-wide association study identifies multiple HLA loci for sarcoidosis susceptibility

Sarcoidosis is a complex systemic disease. Our study aimed to (1) identify novel alleles associated with sarcoidosis susceptibility; (2) provide an in-depth evaluation of HLA alleles and sarcoidosis susceptibility and (3) integrate genetic and transcription data to identify risk loci that may more directly impact disease pathogenesis. We report a genome-wide association study of 1335 sarcoidosis cases and 1264 controls of European descent (EA) and investigate associated alleles in a study of African Americans (AA: 1487 cases and 1504 controls). The EA and AA cohort was recruited from multiple United States sites. HLA alleles were imputed and tested for association with sarcoidosis susceptibility. Expression quantitative locus and colocalization analysis were performed using a subset of subjects with transcriptome data. Forty-nine SNPs in the HLA region in HLA-DRA, -DRB9, -DRB5, -DQA1 and BRD2 genes were significantly associated with sarcoidosis susceptibility in EA, rs3129888 was also a risk variant for sarcoidosis in AA. Classical HLA alleles DRB1*0101, DQA1*0101 and DQB1*0501, which are highly correlated, were also associated with sarcoidosis. rs3135287 near HLA-DRA was associated with HLA-DRA expression in peripheral blood mononuclear cells and bronchoalveolar lavage from subjects and lung tissue and whole blood from GTEx. We identified six novel SNPs (out of the seven SNPs representing the 49 significant SNPs) and nine HLA alleles associated with sarcoidosis susceptibility in the largest EA population. We also replicated our findings in an AA population. Our study reiterates the potential role of antigen recognition and/or presentation HLA class II genes in sarcoidosis pathogenesis.

Pleiotropic Roles of a KEAP1-Associated Deubiquitinase, OTUD1

Protein ubiquitination, which is catalyzed by ubiquitin-activating enzymes, ubiquitin-conjugating enzymes, and ubiquitin ligases, is a crucial post-translational modification to regulate numerous cellular functions in a spatio-temporal-specific manner. The human genome encodes ~100 deubiquitinating enzymes (DUBs), which antagonistically regulate the ubiquitin system. OTUD1, an ovarian tumor protease (OTU) family DUB, has an N-terminal-disordered alanine-, proline-, glycine-rich region (APGR), a catalytic OTU domain, and a ubiquitin-interacting motif (UIM). OTUD1 preferentially hydrolyzes lysine-63-linked ubiquitin chains in vitro; however, recent studies indicate that OTUD1 cleaves various ubiquitin linkages, and is involved in the regulation of multiple cellular functions. Thus, OTUD1 predominantly functions as a tumor suppressor by targeting p53, SMAD7, PTEN, AKT, IREB2, YAP, MCL1, and AIF. Furthermore, OTUD1 regulates antiviral signaling, innate and acquired immune responses, and cell death pathways. Similar to Nrf2, OTUD1 contains a KEAP1-binding ETGE motif in its APGR and regulates the reactive oxygen species (ROS)-mediated oxidative stress response and cell death. Importantly, in addition to its association with various cancers, including multiple myeloma, OTUD1 is involved in acute graft-versus-host disease and autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and ulcerative colitis. Thus, OTUD1 is an important DUB as a therapeutic target for a variety of diseases.

Whole Exome Sequencing Identified Two Single Nucleotide Polymorphisms of Human Leukocyte Antigen-DRB5 in Familial Sarcoidosis in China

BACKGROUND

Sarcoidosis is a multisystem granulomatous disorder whose etiology is related to genetic and immunological factors. Familial aggregation and ethnic prevalence suggest a genetic predisposition and inherited susceptibility to sarcoidosis.

OBJECTIVE

This study aimed to identify suspected risk loci for familial sarcoidosis patients.

METHODS

We conducted whole exome sequencing on two sarcoidosis patients and five healthy family members in a Chinese family for a case-control study. The two sarcoidosis patients were siblings who showed chronic disease.

RESULTS

The Gene Ontology results showed single nucleotide polymorphisms in three genes, including human leukocyte antigen (HLA)-DRB1, HLA-DRB5, and KIR2DL4, associated with both 'antigen processing and presentation' and 'regulation of immune response.' Sanger sequencing verified two nonsynonymous mutations in HLA-DRB5 (rs696318 and rs115817940) located on 6p21.3 in the major histocompatibility complex (MHC) class II beta 1 region. The structural model simulated on Prot- Param protein analysis by the Expert Protein Analysis System predicted that the hydropathy index changed at two mutation sites (rs696318: p.F96L, -1.844 to -1.656 and rs115817940: p.T106N, -0.322 to -0.633), which indicated the probability of changes in peptide-binding selectivity.

CONCLUSION

Our results indicated that two nonsynonymous mutations of HLA-DRB5 have been identified in two sarcoidosis siblings, while their healthy family members do not have the mutations. The two HLA-DRB5 alleles may influence genetic susceptibility and chronic disease progression through peptide mutations on the MHC class II molecule among the two affected family members.

Sarcoidosis in Jordan: A Study of the Clinical Phenotype and Disease Outcome

OBJECTIVES

This study aims to evaluate the clinical phenotypic features of sarcoidosis in a single-center academic hospital in Jordan.

PATIENTS AND METHODS

A retrospective file review was performed at an academic medical center in Jordan that included all patients diagnosed with sarcoidosis between January 2000 and December 2018. A total of 150 patients with sarcoidosis (38 males, 112 females; mean age 47.8±11.7 years; range, 17 to 79 years) were evaluated. Clinical data extracted from the files included the sex of the patient, the age at time of diagnosis, diagnosis date, the season during which the diagnosis was established, and smoking history. Biopsy histopathology, spirometry, nerve conduction, echocardiography, and imaging reports including plain radiographs, ultrasonographic, magnetic resonance and computed tomography reports were reviewed. Data including laboratory values, medication usage, clinical outcomes, and morbidity/mortality were collected. Pulmonary function tests including spirometry and lung volumes along with the diffusing capacity for carbon monoxide were reviewed for the presence of restriction, obstruction or reduction in the diffusion capacity of carbon monoxide. Identification of extra-thoracic organ involvement was determined in each patient in accordance with the criteria suggested by the updated World Association of Sarcoidosis and Other Granulomatous Disorders.

RESULTS

A total of 77.3% of the patients were diagnosed by biopsy. One case of Lofgren's syndrome was identified. Of the patients, 18.0% had isolated pulmonary sarcoidosis, 75.3% had pulmonary and extra-pulmonary sarcoidosis and 6.7% had isolated extra-pulmonary sarcoidosis while 81.3% had respiratory symptoms, mostly shortness of breath and cough. Extra-thoracic organ involvement mostly involved the musculoskeletal system (33%) followed by the skin (20%). Female patients had more extra-thoracic involvement but the sex difference was only statistically significant for cutaneous involvement. Of the patients, 84% received treatment while 20% had disease remission during the first two years after diagnosis and 70% required treatment beyond two years after diagnosis.

CONCLUSION

Various sarcoidosis clinical phenotypes are seen among Jordanian patients. Jordanian females are more affected by the disease and have more extra-thoracic involvement compared to male patients. A large number of the study patients received treatment.

SKP2- and OTUD1-regulated non-proteolytic ubiquitination of YAP promotes YAP nuclear localization and activity

Dysregulation of YAP localization and activity is associated with pathological conditions such as cancer. Although activation of the Hippo phosphorylation cascade is known to cause cytoplasmic retention and inactivation of YAP, emerging evidence suggests that YAP can be regulated in a Hippo-independent manner. Here, we report that YAP is subject to non-proteolytic, K63-linked polyubiquitination by the SCF^SKP2 E3 ligase complex (SKP2), which is reversed by the deubiquitinase OTUD1. The non-proteolytic ubiquitination of YAP enhances its interaction with its nuclear binding partner TEAD, thereby inducing YAP's nuclear localization, transcriptional activity, and growth-promoting function. Independently of Hippo signaling, mutation of YAP's K63-linkage specific ubiquitination sites K321 and K497, depletion of SKP2, or overexpression of OTUD1 retains YAP in the cytoplasm and inhibits its activity. Conversely, overexpression of SKP2 or loss of OTUD1 leads to nuclear localization and activation of YAP. Altogether, our study sheds light on the ubiquitination-mediated, Hippo-independent regulation of YAP.

Epidemiology of Sarcoidosis in a Prospective Cohort Study of U.S. Women

RATIONALE

Sarcoidosis is a systemic granulomatous and inflammatory disorder that most often involves the lungs but also affects many other organs. Data on sarcoidosis from large epidemiological studies remain scarce.

OBJECTIVES

To evaluate the baseline prevalence and 22-year incidence of sarcoidosis and their associations with demographic and geographic characteristics in a large cohort of U.S. women.

METHODS

The Nurses' Health Study II is a prospective cohort study of U.S. female nurses enrolled in 1989 (aged 25-44 yr, n = 116,430). Data on major illnesses were collected through biennial questionnaires (1989-2011). Cases were identified by the nurses' self-report of physician-diagnosed sarcoidosis. Associations of demographic and geographic characteristics with sarcoidosis were evaluated by logistic regression and Cox models.

MEASUREMENTS AND MAIN RESULTS

A total of 377 sarcoidosis cases were identified. The baseline prevalence was 100/100,000 women. The average annual incidence rate was 11/100,000 during 2,275,028 person-years of follow up. Incidence rate increased with age (P = 0.003), from 9 to 15/100,000 in women aged less than 35 to 55 or more years, respectively. Black women had a higher prevalence (odds ratio, 5.24; 95% confidence interval, 2.87-9.55) and incidence (hazard ratio, 3.80; 95% confidence interval, 2.31-6.24) than white women. Across U.S. regions, more than twofold differences were observed in sarcoidosis prevalence and incidence, with consistently higher rates in the Northeast.

CONCLUSIONS

We provide recent national data on the epidemiology of sarcoidosis among U.S. women. Important differences in prevalence and incidence were observed across U.S. regions. Large epidemiological studies are needed to better understand the causes of the observed demographic and geographic differences in sarcoidosis.

Genetics of Sarcoidosis

Sarcoidosis is a disease with highly variable presentation and progression; although it is hypothesized that disease phenotype is related to genetic variation, how much of this variability is driven by genetic factors is not known. The HLA region is the most strongly and consistently associated genetic risk factor for sarcoidosis, supporting the notion that sarcoidosis is an exposure-mediated immunologic disease. Most of the genetic etiology of sarcoidosis remains unknown in terms of the specific variants that increase risk in various populations, their biologic functions, and how they interact with environmental exposures.