Linkage between TIM3 genotype and human HER2 vaccine response in Diversity Outbred (DO) HER2 transgenic (Tg) mice

Abstract

Abstract Regulatory T cell (Treg) depletion boosts HER2 vaccine response in human HER2 transgenic (Tg) mice. To test whether polymorphisms of Treg-associated genes impact vaccine response, individually distinct F1(DOxB6 HER2 Tg) mice were vaccinated 2× with Adv/HER2 to generate highly variable responses. Single nucleotide polymorphisms (SNP) of 16 candidate genes were analyzed by MonsterPlex sequencing or TaqMan assay, with TIM3 showing an association with vaccine response. There are14 SNPs in the 2kb proximal promoter region and 10 SNPs in a 1kb region containing TIM3 exon 7. Four distinct TIM3 genotypes were identified for either region with one genotype consistently matching between the promoter and exon 7 loci, i.e. the CAST/EiJ strain genotype. Analysis of 84 vaccinated DOxB6 HER2 Tg mice using a tag SNP rs28230613 showed that mice with homozygous CC produce HER2 Ab at 26.9±28.9 μg/mL, and those with heterozygous CA (CAST/Eij genotype) 12.8±19.4 μg/mL (p=0.0075). T cell response was absent in most CA heterozygotes. Relative transcript levels of splenocyte TIM3 over CD4 showed heterozygotes at 2.06±2.27 and homozygotes 0.54±0.51 (p=0.0073, n=24), indicating higher TIM3 transcript in CA heterozygotes. Thus, CAST/EiJ TIM3 genotype is associated with higher TIM3 transcript level and lower vaccine response to self HER2. This correlation is absent in mice depleted of CD25+ Treg, implicating Treg and their TIM3 in regulating HER2 vaccine response. The segregation of TIM3 genotype with vaccine response is not absolute, suggesting additional molecular regulation in HER2 vaccine response. CA76340