Selective Loss of Responsiveness to Exogenous but Not Endogenous Cyclic-Dinucleotides in Mice Expressing STING-R231H

Abstract

Stimulator of interferon genes (STING) plays a central role in innate immune responses to viral and intracellular bacterial infections, and cellular damage. STING is a cytosolic sensor of cyclic dinucleotides (CDNs) including those produced by pathogenic bacteria and those arising endogenously as products of the DNA sensor cGAS (e.g., 2 ′ 3 ′ cGAMP). The two most common alternative allelic variants of STING in humans are STING-R71H-G230A-R293Q (STING-HAQ) and STING-R232H that are found in 20.4% and 13.7-17.6% of the population, respectively. To determine the biologic consequences of these genotypic variations, we generated knock-in mice containing the murine equivalents of each variant and studied their responsiveness to CDNs. Homozygous STING-HAQ (R71H-I229A-R292Q) and STING-R231H mice were found to be unresponsive to all exogenous CDNs tested (ci-di-GMP, ci-di-AMP, 3 ′ 3 ′ cGAMP and Rp,Rp-CDA). Responses of homozygous STING-HAQ mice to endogenous 2 ′ 3 ′ cGAMP was also greatly impaired. However, homozygous STING-R231H mice are fully responsive to 2 ′ 3 ′ cGAMP. Analysis of heterozygous mice revealed reduced responsiveness to exogenous and endogenous CDNs in mice carrying a single copy of STING-HAQ, while STING-R231H heterozygous mice exhibit reduced responsiveness to exogenous but not endogenous CDNs. These findings confirm and extend previous reports by demonstrating differing impact of allelic variation of STING on the ability to sense and respond to exogenous vs. endogenous CDNs. Finally, the STING-R231H variant mouse represents a useful tool with which to examine the relative contributions of STING sensing of exogenous and endogenous CDNs in the context of bacterial infections and CDN-based cancer immunotherapeutics.

STING orchestrates the crosstalk between polyunsaturated fatty acid metabolism and inflammatory responses

“…However, several recent reports highlight that, while immune cells express high STING levels, some other cell types express low STING ( Sun et al., 2009 ; Thomsen et al., 2016 ). Furthermore, STING levels are also heterogeneous among human populations; for example, the R71H-G230A-R293Q-STING (HAQ-STING) haplotype ( Jin et al., 2011 ) is expressed at lower levels than wild-type (WT)-STING ( Walker et al., 2020 ). This raises questions concerning the impact of systemic administration of STING agonists in these contexts of low STING levels, in particular in the light of non-immune cells playing a central role in the regulation of organ-specific inflammation ( Krausgruber et al., 2020 ).…”

Au naturale: use of biologically derived cyclic di-nucleotides for cancer immunotherapy

“…While WT STING can respond to 2 0 3 0 -cGAMP, 3 0 3 0 -cGAMP, c-di-GMP and c-di-AMP to varying extents, R232H and R293Q exhibited reduced induction by c-di-GMP, c-di-AMP and 3 0 3 0 -cGAMP while maintaining a robust response to 2 0 3 0 -cGAMP [101]. Knock-in mice of HAQ and R232H STING alleles have been generated and are useful tools to examine the in vivo activity of various STING agonists to these alleles in vivo [102]. Results from these mice generally support the in vitro findings that these STING alleles are less responsive to exogenous CDNs (3 0 3 0 -c-di-GMP, 3 0 3 0 -c-di-AMP and 3 0 3 0 -cGAMP).…”

The Age of Cyclic Dinucleotide Vaccine Adjuvants

“…Previous studies had similar findings on the selectivity of CDNs in activating STING variants in mice. The R231A [ 49 ] or R231H [ 50 ] change in the mouse STING rendered the variants selectively to lose the response to CDG but not cGAMP.…”

“…Accumulating evidence in humans [ 90 , 91 , 100 , 101 ] and mouse models [ 50 , 51 , 102 ] indicated that the HAQ and H232 alleles are impaired in the STING function. CDN-adjuvanted vaccines aim to protect the general public from the pandemic and endemic.…”

“…CDN derivatives that activate HAQ and H232 STING in vivo are highly desirable. Notably, the NOD mice, which contain an N210D of STING [ 47 ], and the R231H mouse [ 50 ] react to cGAMP but not CDG for type I IFNs production. Thus, it is possible to design a CDN that activates H232 or even HAQ STING in vivo.…”