Zachary T. Peters
United States
Immune checkpoint VISTA on keratinocytes suppresses Sting-mediated Type I interferon responses that mediate skin injury by ultraviolet light.
Zachary Peters1, Lindsay Mendyka1, Angelique Cortez1, Grace Crossland1, Jvoughnn Blake1, William Rigby2, Christopher Burns1, Randolph Noelle3 and Sladjana Skopelja-Gardner1
1Dartmouth Geisel School of Medicine, Lebanon, NH, 2Dartmouth Hitchcock Medical Center, Lebanon, PA, 3Geisel School of Medicine at Dartmouth, Lebanon, NH
Abstract
Background
Type I interferons (IFN-Is) play an essential role in anti-viral and anti-tumor immunity but can be persistently upregulated and drive photosensitivity in chronic autoimmune diseases like lupus. Previous studies have suggested that antibody mediated activation of immune checkpoint VISTA can suppress IFN-I. We have previously showed that VISTA deficient mice and mice with conditional deletion of VISTA in their keratinocytes (KRT14creVsirfl/fl) have elevated baseline and UV-induced skin IFN-I responses. Here we demonstrate that immune checkpoint VISTA restrains UV-induced skin injury in a manner at least in part driven by STING-mediated IFN-I signaling.
Methods
WT B6, Vsir-/- (VISTA-deficient), KRT14creVsirfl/fl(keratinocyte VISTA deficient), cre-Vsirfl/fl female mice and Vsir.Sting-/- mice (3 mo) were exposed to an acute dose of UVB (500mJ/CM2 ) and their cutaneous lupus activity index (CLASI) was calculated as the sum of scores for mouse ears, upper and lower backs for erythema, scaling and scarring. Skin infiltrating cells were quantified by flow cytometry 2 days post UVB exposure. Subsets of WT or Vsir-/- mice were given anti-interferon (IFNAR) antibody 3 hours post UVB exposure to test whether photosensitivity observed in the absence of VISTA was driven by IFN-I. To validate a role for VISTA in regulating UV-induced skin injury on non-hematopoietic cells B6-B6 and B6-Vsir-/- chimeric mice were generated by injecting WT mouse bone marrow into lethally irradiated WT or Vsir-/- mice. B6-B6 and B6-Vsir-/- bone marrow chimeras were rested for 7 weeks prior to acute UVB exposure, when CLASI scoring and flow cytometry was performed.
Results
Vsir-/- and KRT14creVsirfl/fl mice had elevated CLASI scores, increased Ly6CHI monocytes and higher CD8:Treg ratios in their skin post UVB. B6-Vsir-/- chimeras containing WT immune cells exhibited higher CLASI scores than WT B6 chimera controls, comparable to Vsir-/- mice. Absence of STING (Vsir.Sting-/- mice) reduced UV-induced CLASI scores and immune cell infiltration at 48 hours post UVB to the same degree achieved by treating Vsir-/- and KRT14creVsirfl/fl by I.P. with an anti-interferon receptor (IFNAR) antibody. Importantly, Vsir-/- keratinocytes expressed higher UV-induced IFN-I responses when cultured ex vivo, which was reduced in Vsir.Sting-/- keratinocytes. Antibody-mediated VISTA activation on human keratinocytes also reduced their UV-induced IFN-I responses.
Conclusions
Taken together this data suggests that STING driven IFN-I, produced in part by keratinocytes is a key driver of UV-induced skin injury that is regulated by VISTA, underscoring a potential to target VISTA to mitigate UV-driven skin inflammation in lupus.
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