The Broad Spectrum Mixed-Lineage Kinase 3 Inhibitor URMC-099 Prevents Acute Microgliosis and Cognitive Decline in a Mouse Model of Perioperative Neurocognitive Disorders

Abstract

Background: Perioperative neurocognitive disorders (PND) are serious complications that afflict up to 50% of surgical patients and for which there are no disease-modifying therapeutic options. We developed the broad spectrum mixed lineage kinase 3 inhibitor URMC-099 to inhibit pathological innate immune responses that underlie neuroinflammation-associated cognitive dysfunction. Here, we test the hypothesis that prophylactic treatment with URMC-099 can prevent surgery-induced neuroinflammation and cognitive impairment in mice following orthopedic surgery-induced PND. Methods: We performed orthopedic surgery by fracturing the tibia of the left-hind limb with intramedullary fixation under general anesthesia and analgesia. We administered URMC-099 (10 mg/kg, i.p.) prophylactically via three intraperitoneal injections. We used two-photon microscopy and CLARITY with light-sheet microscopy to define surgery-induced changes in microglial dynamics and morphology. We assessed cognitive dysfunction following surgery using the What-Where-When task and the Memory Load Object Discrimination task. In surgically-treated samples, we analyzed fracture callouses using microcomputed tomography and histomorphometry analyses. Findings: Orthopedic surgery induced microglial activation in the hippocampus and cortex without overtly affecting microglial process dynamics. Surgically-treated mice exhibited impaired object place and identity discrimination, indicating cognitive dysfunction. URMC-099 prophylaxis prevented surgery-induced microgliosis and memory impairment. Analysis of fracture callouses showed no effect of URMC-099 on fracture healing. Interpretation: These findings show that prophylactic URMC-099 treatment is sufficient to prevent surgery-induced microgliosis and cognitive impairment without interfering with the fracture healing process. Funding Statement: Design, synthesis and validation of URMC-099 was supported by NIH grants P01MH64570 and RO1 MH104147 (HAG). The study was supported by the NIH RO1 AG057525 (NT). Declaration of Interests: URMC-099 is owned by URMC (HA Gelbard. lead inventor: patent nos. US 8,846,909 B2; 8,877,772; and 9,181,247 and associated international patents). HAG has no commercial disclosures regarding URMC-099 at present. Ethics Approval Statement: All animal procedures were carried out under protocols approved by Duke University Medical Center and University of Rochester Medical Center, Institutional Animal Care and Use Committee under the National Research Council Guide for the Care and Use of Laboratory Animals, 8th edition. Both Duke University and University of Rochester Medical Center are AAALAC accredited institutions.