P7C3-A20 Attenuates Microglial Inflammation and Brain Injury after ICH through Activating the NAD+/Sirt3 Pathway

Abstract

Intracerebral hemorrhage (ICH) is lethal but lacks effective therapies. Nicotinamide adenine dinucleotide (NAD⁺) is a central metabolite indispensable for a broader range of fundamental intracellular biological functions. Reduction of NAD⁺ usually occurs after acute brain insults, and supplementation of NAD⁺ has been proven neuroprotective. P7C3-A20 is a novel compound featuring its ability to facilitate the flux of NAD⁺. In this study, we sought to determine the potential therapeutic value of P7C3-A20 in ICH. In collagenase-induced ICH mouse models, we found that P7C3-A20 treatment could diminish lesion volume, reduce blood-brain barrier (BBB) damage, mitigate brain edema, attenuate neural apoptosis, and improve neurological outcomes after ICH. Further, RNA sequencing and subsequent experiments revealed that ICH-induced neuroinflammation and microglial proinflammatory activities were significantly suppressed following P7C3-A20 treatment. Mitochondrial damage is an important trigger of inflammatory response. We examined mitochondrial morphology and function and found that P7C3-A20 could attenuate OxyHb-induced impairment of mitochondrial dynamics and functions in vitro. Mechanistically, Sirt3, an NAD⁺-dependent deacetylase located in mitochondria, was then found to play a vital role in the protection of P7C3-A20 against mitochondrial damage and inflammatory response. In rescue experiments, P7C3-A20 failed to exert those protective effects in microglia-specific Sirt3 conditional knockout (CKO) mice. Finally, preclinical research revealed a correlation between the plasma NAD⁺ level and the neurological outcome in ICH patients. These results demonstrate that P7C3-A20 is a promising therapeutic agent for neuroinflammatory injury after ICH and exerts protective actions, at least partly, in a Sirt3-dependent manner.