HSP90B1 Regulates TLR-dependent Monocyte Signaling and its Common Variants are Associated with BCG-specific T-cell Responses and Protection from Pediatric TB Disease

Introduction HSP90B1 is a chaperone for multiple Toll-like receptors (TLRs), regulates innate immune signaling in murine myeloid cells and is expressed in T-cells. We hypothesized human HSP90B1 regulates monocyte responses to Mycobacterium tuberculosis (Mtb) and that its variants are associated with T-cell responses to the BCG vaccine and susceptibility to TB disease.

Methods & Results We screened 17 haplotype-tagging HSP90B1 gene region SNPs for association with BCG-induced immune responses in South African infants vaccinated with BCG at birth. We stimulated peripheral blood drawn at 10 weeks of age with BCG in a whole blood cytokine assay. Three HSP90B1 SNPs (rs10507172, 10507173, and 2164747) were associated with increased IL-2 secretion (P<0.05, generalized linear model). SNPrs10507173 was associated with increased IL-2 production in the CD4+ T-cell subset (p=0.028, ANOVA) based on intracellular cytokine staining and flow cytometry. The same three alleles were associated with protection from pediatric TB disease in a gene association study of 226 children who contracted tuberculosis compared with 626 controls who remained healthy (dominant model, unadjusted p<0.05, OR 0.58–0.72; after adjusting for ethnicity, p<0.05 for 2/3 SNPs). We used CRISPR/Cas9 gene editing to reduce HSP90B1 expression in U937 monocyte cells. Relative to controls, HSP90B1-deficient cells secreted less TNF when exposed to TLR1/2/6 (p=0.02) and TLR4 (p=0.01) ligands and Mtb whole cell lysate (p=0.001).

Conclusion These data suggest HSP90B1 deficiency is associated with an impaired monocyte response to Mtb ligands. In infants, HSP90B1 variants are associated with increased BCG-specific IL-2 responses T-cells and protection from TB disease.