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

Sarcoidosis in Beryllium Exposed Workers: A Case-Case Study

BACKGROUND

Despite the utility of the beryllium lymphocyte proliferation test (BeLPT), distinguishing sarcoidosis, a disease of unknown etiology, from chronic beryllium disease (CBD), has long posed a diagnostic challenge. It is unclear if beryllium-exposed sarcoidosis cases (Be-exp-Sarc) are clinically distinct from CBD, or are misdiagnosed cases of CBD.

METHODS

We performed a case-case study of 40 beryllium-exposed individuals diagnosed with Be-exp-Sarc compared to 40 frequency-matched CBD cases. We compared demographics, exposure, clinical, physical, and radiographic characteristics and HLA DBPI E69 genotype.

RESULTS

Compared to CBD, Be-exp-Sarc cases were diagnosed at a younger age, had lower lung function, were less likely to have normal radiographic imaging, were more likely to have massive adenopathy and extra-thoracic manifestations and were more likely to have been prescribed systemic immunosuppressive therapy. Be-exp-Sarc tended to have fewer years of beryllium exposure, but there were no significant differences in the amount of beryllium exposure. HLA DPBI E69 was present in 53% of Be-exp-Sarc cases, not different from the general population, versus 92% of CBD cases (p < 0.001).

CONCLUSIONS

While a number of differences were observed, the only absolute distinguishing features were lack of confirmed beryllium sensitization in Be-exp-Sarc and lack of extra-thoracic manifestations in CBD. These findings suggest that Be-exp-Sarc may be distinct from CBD, and beryllium or some other workplace exposure may possibly play an as yet to be defined etiologic role, although the possibility that these cases could be due to selection bias from heightened surveillance in beryllium workforces cannot be excluded.

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.

Humoral pathways of innate immune regulation in granuloma formation

The humoral arm of mammalian innate immunity regulates several molecular mechanisms involved in resistance to pathogens, inflammation, and tissue repair. Recent studies highlight the crucial role played by humoral mediators in granulomatous inflammation. However the molecular mechanisms linking the function of these soluble molecules to the initiation and maintenance of granulomas remain elusive. We propose that humoral innate immunity coordinates fundamental physiological processes in macrophages which, in turn, initiate activation and transformation events that enable granuloma formation. We discuss the involvement of humoral mediators in processes such as immune activation, phagocytosis, metabolism, and tissue remodeling, and how these can dictate macrophage functionality during granuloma formation. These advances present opportunities for discovering novel disease factors and developing targeted, more effective treatments for granulomatous diseases.