Development of Inflammatory Hypoxia and Prevalence of Glycolytic Metabolism in Progressing Herpes Stromal Keratitis Lesions.

Chronic inflammation in tissues often causes the development of hypoxia. Herpes stromal keratitis (HSK) is a corneal chronic inflammatory condition that develops in response to recurrent HSV-1 infection. In this study, we investigated the development of hypoxia, the expression of hypoxia-associated glycolytic genes in HSV-1 infected corneas, and the outcome of blocking hypoxia-inducible factor (HIF) dimerization on the severity of HSK. Our results showed the development of hypoxia, an elevated expression of hypoxia-associated glycolytic genes, and an increased level of lactate in corneas with progressing HSK lesions. The magnitude of hypoxia correlated with the extent of neutrophils infiltrating the infected corneas, and the depletion of neutrophils reduced the development of hypoxia in infected corneas. Additionally, in progressing HSK lesions, nuclear localization of HIF-2α protein was detected in corneal epithelial cells, whereas HIF-1α protein stabilization was observed in infiltrating immune cells. Administration of acriflavine drug to HSV-1-infected mice inhibited nuclear accumulation of HIF-1α and HIF-2α protein in immune cell types and epithelial cells, respectively, in infected corneas. As a result, a decreased influx of CD4 T cells and nongranulocytic myeloid cells, but an increased influx of neutrophils, was noted in developing HSK lesions. Interestingly, acriflavine treatment given during the clinical disease period decreased neovascularization but increased the opacity in HSV-1-infected corneas. Taken together, the results of our study lay the foundation to dissect the role of inflammatory hypoxia and hypoxia-associated genes in the pathogenesis of HSK.