Association of TGF-β3 and ANXA11 with pulmonary sarcoidosis in Greek population

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.

Evaluation of genetic risk, its clinical manifestation and disease management based on 18 susceptibility gene markers among West-Slavonic patients with sarcoidosis

Sarcoidosis is a heterogenous, multisystemic inflammatory disease that primarily affects lungs. In this study, we multiplex genotyped 18 single-nucleotide polymorphisms (SNPs) to replicate the findings from previous genome-wide association studies (GWAS) and candidate gene studies, and extended analyses to different clinical manifestations (Lofgren syndrome and chest X-ray [CXR] stages) including treatment response among West-Slavonic subjects (564 sarcoidosis patients and 301 healthy controls). We confirm the replication (with Bonferroni correction) of ANXA11 rs1049550 as protective variant for sarcoidosis (odds ratio [OR]=0.71, p=1.33×10^-3), non-LS (OR=0.66, p=2.71×10^-4) and CXR stages 2-4 (OR=0.62, p=7.48×10^-5) compared to controls in West-Slavonic population. We also validate the association of risk variants C6orf10 rs3129927 (OR=2.61, p=2.60×10^-8), TNFA rs1800629 (OR=1.56, p=6.65×10^-4), ATF6B rs3130288 (OR=2.75, p=1.06×10^-9) and HLA-DQA1 rs2187668 (OR=1.74, p=8.83×10^-4) with sarcoidosis compared to controls. For sub-phenotypes compared to controls, risk variants C6orf10 rs3129927 (OR=5.35, p=1.07×10^-12), TNFA rs1800629 (OR=2.66, p=5.94×10^-7), ATF6B rs3130288 (OR=5.24, p=5.21×10^-13), LRRC16A rs9295661 (OR=2.97, p=4.29×10^-4), HLA-DQA1 rs2187668 (OR=3.14, p=1.09×10^-6) and HLA-DRA rs3135394 (OR=5.23, p=8.25×10^-13) were associated with LS while C6orf10 rs3129927 (OR=1.96, p=4.27×10^-4) and ATF6B rs3130288 (OR=2.15, p=3.36×10^-5) were associated with non-LS. For CXR stages compared to controls, C6orf10 rs3129927 (OR=3.67, p=3.63×10^-11), TNFA rs1800629 (OR=1.84, p=1.32×10^-4), ATF6B rs3129927 (OR=3.63, p=1.82×10^-11), HLA-DQA1 rs2187668 (OR=2.13, p=9.59×10^-5) and HLA-DRA rs3135394 (OR=3.42, p=3.45×10^-10) were risk variants for early CXR stages 0-1 while C6orf10 rs3129927 (OR=1.99, p=5.51×10^-4), ATF6B rs3129927 (OR=2.23, p=3.52×10^-5) and HLA-DRA rs3135394 (OR=1.85, p=2.00×10^-3) were risk variants for advanced CXR stages 2-4. The present findings nominate gene variants as plausible prognostic markers for clinical phenotypes, treatment response and disease resolution/progression and may form the basis for establishing genotype-phenotype relationships in patients with sarcoidosis among West-Slavonic population.

ANXA11 rs1049550 Associates with Löfgren’s Syndrome and Chronic Sarcoidosis Patients

Sarcoidosis is an immune mediated granulomatous disease commonly affecting the lungs. Genome wide association studies identified many genomic regions that are shared among multiple immune mediated diseases. However, ANXA11 gene polymorphism rs1049550 is exclusively associated with sarcoidosis, making it a key gene of interest for sarcoidosis disease pathogenesis. However, sarcoidosis is a heterogeneous disease and contradictory findings for ANXA11 have been reported for disease phenotypes. We performed a case–control association study to investigate if ANXA11 associates with benign (Löfgren’s syndrome (LS)) or chronic sarcoidosis and performed a meta-analysis on previously reported findings. A total of 262 sarcoidosis patients, of which 149 had LS and 113 chronic sarcoidosis, and 363 controls were genotyped for rs1049550. Meta-analysis included allele findings for rs1049550 from 6 additional studies. We found a significantly lower T allele frequency in sarcoidosis patients than in healthy controls (0.30 vs. 0.41, respectively, odds ratio (OR) 0.61, 95% confidence interval (CI) 0.48–0.77, p = 3 × 10⁻⁵). In LS the T allele frequency of 0.33, and in chronic sarcoidosis the T allele frequency of 0.26 were significantly lower than in healthy controls (OR 0.69, 95% CI 0.52–0.92, p = 0.01 and OR 0.51, 95% CI 0.36–0.70, p = 4 × 10⁻⁵, respectively). Meta-analysis including previously published European, African American and Asian cohorts confirmed the association of rs1049550 with sarcoidosis and resulted in a pooled OR of 0.70 (CI 0.66–0.75, p = 3.58 × 10⁻²⁹). Presence of the T allele of rs1049550 in ANXA11 is protective for sarcoidosis, including benign and chronic phenotypes of the disease.

Effect of genotype on the disease course in idiopathic pulmonary fibrosis despite antifibrotic treatment

A genetic predisposition has been identified in 30% of idiopathic pulmonary fibrosis (IPF) cases. Although it is highly probable that the genotype affects the disease susceptibility and course in almost all patients, the specific genotype goes undetected. The aim of the present study was to explore the effects of variants of the genes encoding interleukin-4 (IL-4), mucin 5B (MUC5B), toll interacting protein (TOLLIP), surfactant protein A (SFPTA), transforming growth factor-β (TGF-β) and transporters associated with antigen processing (TAP1 and TAP2) on the course of IPF. A total of 50 patients with IPF were enrolled, and variants of these genes were assessed. Lung function at the time of diagnosis and after 6, 12 and 18 months, and the number of acute exacerbations and deaths in each observation period were measured. ANOVA was used to test the association between gene polymorphisms and the decrease in lung function. There was no significant effect of the gene polymorphisms on the outcomes of patients up to 6 months during the observation period. After 12 months, an effect of an IL-4 single nucleotide polymorphism (SNP) (rs 2070874) on patient outcomes was observed [relative risk (RR) for T allele: 5.6; 95% confidence interval (CI), 0.79-39.0; P=0.053]. The RR of progression in patients with the IL-4 SNP (rs 2243250) and the CT and TT genotypes was 4.3 (95% CI, 1.1-17.5; P=0.046). A total of 18 months after the diagnosis of IPF, an effect of the TOLLIP polymorphism on patient outcome was detected (rs 111521887; risk allele GC; RR: 7.2; 95% CI, 0.97-53.6; P=0.052). Thus, IL-4 and TOLLIP gene polymorphisms may represent disease course-modifying factors, but not drivers of IPF.

Epigenetics and sarcoidosis

Epigenetic modifications are emerging as important regulatory mechanisms of gene expression in lung disease, given that they are influenced by environmental exposures and genetic variants, and that they regulate immune and fibrotic processes. In this review, we introduce these concepts with a focus on the study of DNA methylation and histone modifications and discuss how they have been applied to lung disease, and how they can be applied to sarcoidosis. This information has implications for other exposure and immunologically mediated lung diseases, such as chronic beryllium disease, hypersensitivity pneumonitis, and asbestosis.

Genetics in sarcoidosis

PURPOSE OF REVIEW

Epidemiological and clinical observations as well as familial clustering support the existence of a genetic predisposition to sarcoidosis. In this article, we review the most recent findings in genetics of sarcoidosis and discuss how the identification of risk alleles may help advancing our understanding of disease etiology and development.

RECENT FINDINGS

Genetic studies of sarcoidosis phenotypes have identified novel and ancestry-specific associations. Gene-environment interaction studies highlighted the importance of integrating genetic information when assessing the relationship between sarcoidosis and environmental exposures. A case-control-family study revealed that the heritability of sarcoidosis is only 49%, suggesting the existence of additional important contributors to disease risk. The application of whole-exome sequencing has identified associations with disease activity and prognosis. Finally, gene expression studies of circulating immune cells have identified shared and unique pathways between sarcoidosis and other granulomatous diseases.

SUMMARY

Sarcoidosis genetic research has led to the identification of a number of associations with both sarcoidoses per se and disease phenotypes. Newer sequencing technologies are likely to increase the number of genetic variants associated with sarcoidosis. However, studying phenotypically and ethnically homogeneous patient subsets remains critically important regardless of the genetic approach used.

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.