12-Lipoxygenase Inhibition Suppresses Islet Immune and Inflammatory Responses and Delays Autoimmune Diabetes in Human Gene Replacement Mice.

Type 1 diabetes (T1D) is characterized by the autoimmune destruction of insulin-producing ß cells and involves an interplay between ß cells and cells of the innate and adaptive immune systems. We investigated the therapeutic potential of targeting 12-lipoxygenase (12-LOX), an enzyme implicated in inflammatory pathways in ß cells and macrophages, using a mouse model in which the endogenous mouse Alox15 gene is replaced by the human ALOX12gene. Our findings demonstrate that VLX-1005, a potent 12-LOX inhibitor, effectively delays the onset of autoimmune diabetes in human gene replacement non-obese diabetic (NOD) mice. By spatial proteomics analysis, VLX-1005 treatment resulted in marked reductions in infiltrating T and B cells and macrophages with accompanying increases in immune checkpoint molecules PD-L1 and PD-1, suggesting a shift towards an immune-suppressive microenvironment. RNA sequencing analysis of isolated islets from inhibitor-treated mice revealed significant alteration of cytokine-responsive pathways. RNA sequencing of polarized proinflammatory macrophages showed that VLX-1005 significantly reduced the interferon response. This study highlights a functional equivalence of human ALOX12 and mouse Alox15 in T1D pathogenesis. Our studies provide a platform for the preclinical evaluation of LOX inhibitors and supports the development of 12-LOX inhibitors as a therapeutic strategy for T1D and other inflammatory diseases. Overall design: To investigate the inhibition of 12-lipoxygenase in macrophages, bone marrow was harvested from NOD.hALOX12 mice and bone marrow devired macrophages were isolated to M0 macrophages. M0 macrophages were treated with vehicle or VLX-1005. M0 macrophages were stimulated to M1 macrophages with LPS and IFN-? in the presence of vehicle or VLX-1005 were treated for 4 weeks with VLX-1005 or vehicle. RNA was isolated and processed for RNA-sequencing.