Project Summary/Abstract Neuropathy associated with type 2 diabetes (T2D) is frequently associated with pain and sensory loss. Our incomplete mechanistic understanding of the pathophysiology of nerve injury in T2D hinders our ability to develop more effective drugs and therapeutic strategies. Given the emerging role of myeloid cells, particularly macrophages, across various types of neuropathy, their apparent involvement in diverse forms of nerve injury pain and the known increase in production of the peptide hormone angiotensin II (Ang II) in diabetes, we posit that elevated Ang II in T2D precipitates neuropathy, pain and sensory loss by disrupting myeloid cell development and phenotype. However, many knowledge gaps persist. Our preliminary studies indicate that circulating immature myeloid cell numbers are increased in diet-induced and genetic models of T2D, a change also associated with elevated levels of Ang II in lymphoid tissues. Furthermore, the sensory gain observed in diet-induced T2D is reversible by inhibitors of Ang II production. The overall goal of this project is to identify how Ang II disrupts myeloid cells in T2D, culminating in neuropathy, sensory loss and pain. The first specific aim will assess the extent of alterations to myelopoiesis across the progression from metabolic syndrome to early stage T2D to late-stage T2D, and whether increases in Ang II are causally related. The second specific aim will determine the degree to which T2D modifies tissue-resident myeloid cell function in ways that promote sensory dysfunction. Finally, the third specific aim will determine if opposing T2D-related changes in angiotensin signaling can normalize pathological changes to myeloid cells, thereby reducing sensory dysfunction. Our multidisciplinary approach involves preclinical T2D models, reflexive and voluntary pain-behavioral studies, immunohistochemistry, in vitro live cell functional imaging, single cell RNA and ATAC-sequencing and transcriptomic analysis of human skin biopsies. Our project will unambiguously dissect the nature of Ang II-based myeloid cell disruption to determine the role of the renin-angiotensin system and macrophage-driven inflammation in the development of peripheral neuropathy and chronic pain in T2D. Elucidating the mechanistic underpinnings of sensory loss and pain in T2D neuropathy is critical to advancing our understanding of the underlying mechanism(s), as well as rapid translation into development of new- generation, efficacious, non-opioid analgesics that target such neuro-immune crosstalk.