Zibo Dong

Neuropathy is a common chronic complication of type 1 diabetes mellitus (T1D), an autoimmune disease in which neuroinflammation is considered a key pathological mechanism. P21-activated kinase 4 (PAK4) is a significant factor in this neuroinflammatory process. Higenamine hydrochloride (HGN) possesses anti-inflammatory properties. This study investigated the effects of HGN on T1D and its potential regulation of neuroinflammation via PAK4. We established a T1D mouse model using an intraperitoneal injection of streptozotocin (STZ), followed by HGN administration. The PAK4 inhibitor PF3758309 was given 2 weeks before the experiment ended. Pathological alterations in brain tissues were examined through Nissl and H&E staining. Cognitive function and behavior were assessed using the Morris water maze, elevated plus maze, and open field tests. Molecular docking, cellular thermal shift analysis (CETSA), drug affinity responsive target stability (DARTS) assays, immunofluorescence, and immunoblotting were employed to investigate the binding of HGN to PAK4, its nuclear translocation, and microglial polarization. HGN mitigated brain damage, memory loss, anxiety, and behavioral dysfunction. It also reduced the levels of proinflammatory cytokines (TNF-α and IL-1β) and markers (CD16b, CD11b, and iNOS). Mechanistically, HGN increased PAK4 stability and inhibited M1 polarization via the CRTC2-CREB pathway. PF3758309 diminished the protective effects of HGN and elevated the serum levels of brain damage indicators (S100β and NSE) and inflammatory factors. HGN effectively reduces neuroinflammation and neurological dysfunction in T1D by targeting PAK4, suggesting its potential as a therapeutic agent for diabetes-related complications. Graphical Abstract