Pharmacological activation of LRH-1/NR5A2 triggers an anti-inflammatory phenotypic switch in immune cells from individuals with type 1 diabetes  and improves human islet engraftment/function
The intricate aetiology of type 1 diabetes mellitus (T1DM) implicating a detrimental cross talk between immune cells and insulin producing beta-cells leading to their destruction has stumped the development of effective disease modifying therapies. The discovery that the pharmacological activation of LRH-1/NR5A2 can revert hyperglycemia in pre-clinical mouse models of T1DM by attenuating the autoimmune attack coupled to beta-cell survival/regeneration, prompt us to investigate whether LRH-1/NR5A2-mediated immune tolerization could be achieved in individuals with T1DM and improve islet survival and function subsequent to xenotransplantation. We found that LRH-1/NR5A2 activation using the agonist BL001 blunted the pro-inflammatory genetic signature and cytokine secretome of both monocyte-derived macrophages (MDM1) and mature dendritic cells (mDCs) from individuals with T1DM. Mechanistically, mitohormesis was induced in MDM1 restricting pro-inflammation propagation while mitochondria turnover was increased in mDCs assisting transit towards a tolerogenic phenotype. BL001 treatment also increased T-regulatory cells within the T-cell subpopulation. BL001-treated MDM1, mDCs or T-cells impeded T-effector cell expansion. Engraftment and function of human islets transplanted into hyperglycemic immunocompetent mice was enhanced by BL001 treatment leading to improved glycemia. Collectively, LRH-1/NR5A2 agonism fosters a coordinated re-programming of T1DM immune cells from a pro- to an anti-inflammatory/tolerizing phenotype empowering them to repress cytotoxic T-cell proliferation and facilitates islet engraftment and function after transplantation. Our finding demonstrate the feasibility of re-establishing human immune tolerance within a pro-inflammatory environment, rather than suppression, opening an unprecedent pharmacological therapeutic venue for T1DM.