Hydroxychloroquine (HCQ) is widely used in the treatment of a variety of autoimmune diseases. However, the mechanisms responsible for the immunomodulatory properties of HCQ in T cells remain unclear. Here we used single-cell RNA-sequencing to examine the effect of HCQ on T cells following in vitro stimulation. HCQ treatment led to a reduction in effector CD4+ T cells and upregulation of inhibitory genes including CTLA4 and TNFAIP3 in effector and naive CD4+ T cells, respectively. HCQ induced a significant expansion of effector CD8+ T cells, and significantly upregulated key cytotoxicity genes including GZMA, GZMB, GZMH, KLRD1, NKG7, and PRF1, as well as IFNG expression. Furthermore, HCQ treatment led to a reduction in the CD38+ CD8+ T cell subset, which is characterized by defective cytotoxicity and thought to both play a pathogenic role and increase susceptibility to infections in autoimmunity. We analyzed single-cell RNA-sequencing data in effector CD8+ T cells from lupus patients with or without HCQ treatment and confirmed upregulation of key cytotoxicity genes in patients receiving HCQ. In conclusion, this work provides additional insights into the immunomodulatory effects of HCQ and indicates that HCQ improves T cell cytotoxicity, which could explain a previously suggested protective effect of HCQ against infections in patients with autoimmune diseases.
Sarcoidosis is a chronic disease of unknown origin that develops when a genetically susceptible host is exposed to an antigen, leading to an exuberant immune response characterized by granulomatous inflammation. Although lung involvement is almost universal as well as the leading cause of morbidity and mortality, virtually any organ can be affected. In particular, sarcoidosis of the heart, nervous system, and eyes can be devastating, leading to death, debilitation and blindness, and a multidisciplinary approach involving expert specialists is required for prompt diagnosis and appropriate treatment. Sarcoidosis of the skin can be disfiguring, thus posing a substantial psychologic and social impact on the patients. The diagnosis is often straightforward in the presence of compatible clinical manifestations in patients with biopsy-proven sarcoidosis, but is challenging when extrapulmonary signs/symptoms occur in isolation. Corticosteroids remain the first line therapy, with immunosuppressive or biologic agents being reserved to patients failing or experiencing side effects from steroids or developing refractory disease.