Mutated OAS1 leads to immunodeficiency
Inborn errors of immunity can result in autoinflammatory immunodeficiencies. Type I interferon–inducible oligoadenylate synthetase 1 (OAS1) can initiate antiviral immune responses and is linked to pulmonary alveolar proteinosis with hypogammaglobulinemia. Here, Magg et al. identified four heterozygous OAS1 gain-of-function mutations that cause a polymorphic immunodeficiency in six patients. The OAS1 mutants induced functional and transcriptomic alterations in monocytes, B cells, and T cells, which related to RNase L–dependent cellular dysfunction, apoptosis, protein translation arrest, and cellular RNA degradation. These deficiencies correlated to the altered structure of the OAS1 mutants. Some of these OAS1 gain-of-function patients were cured by hematopoietic stem cell transplantation, suggesting that these immune defects directly contributed to the disease phenotypes. These data give further insight into a rare autoinflammatory immunodeficiency.
Abstract
Analysis of autoinflammatory and immunodeficiency disorders elucidates human immunity and fosters the development of targeted therapies. Oligoadenylate synthetase 1 is a type I interferon–induced, intracellular double-stranded RNA (dsRNA) sensor that generates 2′-5′-oligoadenylate to activate ribonuclease L (RNase L) as a means of antiviral defense. We identified four de novo heterozygous OAS1 gain-of-function variants in six patients with a polymorphic autoinflammatory immunodeficiency characterized by recurrent fever, dermatitis, inflammatory bowel disease, pulmonary alveolar proteinosis, and hypogammaglobulinemia. To establish causality, we applied genetic, molecular dynamics simulation, biochemical, and cellular functional analyses in heterologous, autologous, and inducible pluripotent stem cell–derived macrophages and/or monocytes and B cells. We found that upon interferon-induced expression, OAS1 variant proteins displayed dsRNA-independent activity, which resulted in RNase L–mediated RNA cleavage, transcriptomic alteration, translational arrest, and dysfunction and apoptosis of monocytes, macrophages, and B cells. RNase L inhibition with curcumin modulated and allogeneic hematopoietic cell transplantation cured the disorder. Together, these data suggest that human OAS1 is a regulator of interferon-induced hyperinflammatory monocyte, macrophage, and B cell pathophysiology.
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