Kdm6a deficiency in microglia/macrophages epigenetically silences Lcn2 expression and reduces photoreceptor dysfunction in diabetic retinopathy

Diabetic retinopathy (DR) is one of the leading causes of severe visual impairment worldwide. However, the role of adaptive immune inflammation driven by microglia/macrophages in DR is not yet well elucidated. Kdm6a is a histone demethylase that removes the trimethyl groups of histones H3K27 and plays important biological roles in activating target genes. To elucidate the role of Kdm6a in microglia/macrophages in diabetic retinas, we established diabetic animal models with conditional knockout mice to investigate the impacts of Kdm6a deficiency. The RNA-seq analysis, mass spectrum examination, immunohistochemistry and detection of enzyme activities were used to elucidate the effect of Kdm6a deletion on gene transcription in microglia/macrophages. The expression of Kdm6a was increased in the retinas of diabetic mice compared to the control group. Loss of Kdm6a in microglia/macrophages ameliorated the diabetes-induced retinal thickness decrease, inflammation, and visual impairment. Kdm6a in microglia/macrophages regulated Lcn2 expression in a demethylase activity-dependent manner and inhibited glycolysis progression in photoreceptor cells through Lcn2. These results suggest that Kdm6a in microglia/macrophages aggravated diabetic retinopathy by promoting the expression of Lcn2 and impairing glycolysis progression in photoreceptor cells.