The common TMEM173 HAQ, AQ alleles rescue CD4 T cellpenia, restore T-regs, and prevent SAVI (N153S) inflammatory disease in mice

Abstract

The significance of STING (encoded by the TMEM173 gene), in tissue inflammation and cancer immunotherapy has been increasingly recognized. Intriguingly, common human STING alleles R71H-G230A-R293Q ( HAQ) and G230A-R293Q ( AQ ) are carried by ∼60% of East Asians and ∼40% of Africans, respectively. Here, we examine the modulatory effects of HAQ, AQ alleles on STING-associated vasculopathy with onset in infancy (SAVI), an autosomal dominant, fatal inflammatory disease caused by gain-of-function human STING mutations. CD4 T cellpenia is evident in SAVI patients and mouse models. Using STING knock-in mice expressing common human STING alleles HAQ , AQ , and Q293 , we found that HAQ, AQ , and Q293 splenocytes resist STING-mediated cell death ex vivo, establishing a critical role of STING residue 293 in cell death. The HAQ/SAVI(N153S) and AQ/SAVI(N153S) mice did not have CD4 T cellpenia. The HAQ/SAVI(N153S), AQ/SAVI(N153S) mice have more (∼10-fold, ∼20-fold, respectively) T-regs than WT/SAVI(N153S) mice. Remarkably, while they have comparable TBK1, IRF3, and NFκB activation as the WT/SAVI , the AQ/SAVI mice have no tissue inflammation, regular body weight, and normal lifespan. We propose that STING activation promotes tissue inflammation by depleting T-regs cells in vivo . Billions of modern humans have the dominant HAQ, AQ alleles. STING research and STING-targeting immunotherapy should consider TMEM173 heterogeneity in humans. Teaser: One copy of the common human HAQ or AQ TMEM173 gene prevents the gain-of-function TMEM173 mutant-caused SAVI disease in mice.