Nerve injury-induced protein 1 (Ninjurin1, Ninj1) is a cell-surface adhesion molecule that regulates cell migration and attachment. This study demonstrates the increase in Ninj1 protein expression during development of intestinal inflammation. Ninj1-deficient mice exhibited significantly attenuated bodyweight loss, shortening of colon length, intestinal inflammation, and lesser pathological lesions than wild-type mice. Although more severe inflammation and serious lesions are observed in wild-type mice than Ninj1-deficient mice, there were no changes in the numbers of infiltrating macrophages in the inflamed tissues obtained from WT and Ninj1-deficient mice. Ninj1 expression results in activation of macrophages, and these activated macrophages secrete more cytokines and chemokines than Ninj1-deficient macrophages. Moreover, mice with conditional deletion of Ninj1 in myeloid cells (Ninj1^fl/fl; Lyz-Cre+) alleviated experimental colitis compared with wild-type mice. In summary, we propose that the Ninj1 in myeloid cells play a pivotal function in intestinal inflammatory conditions.

Background: We evaluated the potential neuroprotective effects of naloxone in moderate traumatic brain injury (TBI), focusing on its ability to alleviate neuroinflammation, reduce cognitive impairment, and to influence Janus tyrosine kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling markers. Methods: Male C57BL/6J mice were used to establish an in vivo model of moderate TBI using a stereotaxic impactor. Immediately post-injury, naloxone was administered intraperitoneally (1 mg/kg/day) for 7 days. A total of 72 mice were divided into four groups: Normal, normal with naloxone, TBI, and TBI with naloxone (18 mice in each group). Immunohistochemical analyses and cognitive functions were evaluated across the groups. Results: TBI mice treated with naloxone exhibited significantly reduced brain swelling and cortical tissue loss compared to untreated mice. Naloxone reduced Transforming growth factor beta 2 (TGF-β2) and increased interleukin 11 (IL-11) expression in the brain. Additionally, levels of JAK2, STAT3, and B-cell lymphoma 2 (Bcl-2) were significantly elevated following treatment, while expressions of Tumor protein p53 (p53), Caspase 3, Microtubule-associated proteins 1A/1B light chain 3B (LC3B), and Sequestosome 1 (p62) were reduced. Fluorescence intensities of ionized calcium binding adaptor molecule (Iba-1) and dichloro-dihydro-fluorescein diacetate (DCFH-DA) were enhanced, indicating decreased microglial activation and reactive oxygen species (ROS) production due to naloxone treatment. Cognitive function tests revealed improved performance in TBI mice treated with naloxone, demonstrated by decreased alteration rates in the Y-maze test and improved preference index scores in the novel object recognition (NOR) test. Conclusions: Naloxone shows potential for neuroprotection and enhanced cognitive performances, which may be associated with modulation of JAK2/STAT3 signaling in a mouse model of moderate TBI.