STAT1 gain of function mutation impairs immune response to viral infections

Abstract

Abstract The coordinated effort of the immune system in host defense is dependent upon the proper release and interpretation of different cytokine signals. Several examples of monogenic diseases targeting the JAK-STAT pathway reveal there is still a critical need to understand basic principles of cytokine signaling and cytokine output. For example, patients with STAT1 gain-of-function (GOF) mutations exhibit a type 1/IFN-gamma bias that antagonizes a type 3/IL-17 immune response important for controlling fungal infection, yet patients also, paradoxically, exhibit chronic and sometimes lethal viral infections. Using a novel conditional knock in STAT1-GOF mouse model, we demonstrate that STAT1-GOF mice respond poorly to viral infections that are easily controlled by WT mice, such as MCMV and LCMV-Armstrong. High-dimensional flow cytometry and scRNA-seq reveal an impaired NK and CD8 T cell effector response in STAT1-GOF mice that is not simply due to an exhaustion phenotype. Instead, STAT1-GOF mice respond poorly to viral infections due to an unexpected defect in IFN-gamma production early during the innate immune response, leading to a cytokine storm, immunopathology, and an impaired adaptive immune response. scATAC/RNA-seq uncovers altered usage of different STAT complexes in STAT1-GOF mice, leading to a misinterpretation of early innate-stimulating cytokines. These results provide insight into why patients with interferonopathies or elevated interferons respond poorly to viral infections and highlight the importance of properly tuning STAT1 during an immune response. R.L.P. was supported by a Postdoctoral Research Associate (PRAT) fellowship from the National Institute of General Medical Sciences (NIGMS), award number 1Fi2GM137942-01