Traumatic brain injury (TBI)-associated coagulopathy is a life-threatening complication characterized by systemic coagulation dysfunction and increased mortality; however, the underlying regulatory mechanisms remain incompletely understood.In this study, we investigated the potential role of hypoxia-inducible factor-2α (HIF-2α) in endothelial dysfunction and tissue factor pathway inhibitor (TFPI)-associated coagulation imbalance during TBI-associated coagulopathy. Building on our previous transcriptomic analysis identifying TFPI upregulation in trauma-induced coagulopathy, we further explored its upstream regulatory mechanism in a rat TBI model. Notably, integrative analysis revealed partial overlap between the transcriptomic profiles of rat injured cortex and clinical whole-blood samples, both highlighting dysregulated coagulation pathways and converging on TFPI as a key candidate. TBI-induced coagulopathy was characterized by coagulation dysfunction, accompanied by decreased endothelial HIF-2α protein stability associated with calpain activation, with concomitant upregulation of TFPI in cortical tissue. In cultured HUVECs, TNF-α combined with hypoxia/reoxygenation stress induced endothelial HIF-2α protein suppression and TFPI upregulation. Pharmacological stabilization of HIF-2α using dimethyloxalylglycine (DMOG) partially restored coagulation parameters in vivo and attenuated TFPI induction under stress conditions. Mechanistically, structural prediction analysis identified a potential interaction between HIF-2α and the HRE-containing region of the TFPI promoter. Chromatin immunoprecipitation assays further supported the association of HIF-2α with this promoter region. Moreover, AAV-mediated TFPI overexpression partially reversed the protective effects of DMOG-mediated HIF-2α stabilization on coagulation and neurological outcomes.Collectively, these findings suggest that HIF-2α may be involved in the transcriptional regulation of TFPI in endothelial cells under early TBI-associated stress conditions and may contribute to coagulation dysfunction following TBI. This pathway may provide a potential link between endothelial stress responses and trauma-induced coagulopathy.
The neuropathology of human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND) brains is similar to Alzheimer's disease brains in terms of an accumulation of the neurotoxic amyloid beta (Aβ) peptide. To test this hypothesis, we measured the levels of amyloid precursor protein (APP) and Aβ in HAND cerebrospinal fluid. We observed a 2-fold reduction in APP levels contrasted by an increase in Aβ in people living with HIV. However, the mechanism underlying these effects is challenging to elucidate. HIV may exert its neurotoxic effects in the CNS through the actions of the envelope glycoprotein gp120. Therefore, we exposed rat cortical neurons to this envelope protein. Neurons exposed to gp20 exhibited a morphological pathology as well as a 2-fold increase in the cellular levels of APP and Aβ42. The effect of gp120 was blocked by AMD3100, a CXCR4 antagonist. We then determined APP and Aβ levels in the hippocampus of aged gp120-transgenic (tg) mice, an animal model of HAND. Gp120 transgenic animals also exhibit a ~2-fold increase in APP and Aβ42 levels compared to wild type (WT). There was no change in APP mRNA, suggesting that the increase in Aβ42 could be due to APP processing. We then measured the hippocampal levels of beta-site APP cleaving enzyme-1 (BACE-1), and presenilin 1 and 2, nicastrin, and anterior pharynx defective 1 (APH1), components of the gamma secretase complex, in WT and gp120tg mice. We observed no significant changes in BACE1 levels; however, presenilin 1 levels were significantly increased, whereas nicastrin levels were significantly decreased in gp120 tg mice. Together, our data suggest that gp120 may be an important mechanism contributing to Aβ accumulation in HAND. This research advances our understanding of the mechanisms contributing to HAND, and establishes a novel mechanism for gp120 neurotoxicity involving the production of toxic protein.
Cervical spinal cord injury (SCI) can interrupt descending bulbospinal pathways that support breathing, increasing the risk of serious respiratory complications and death. The C2 spinal hemisection (C2SH) model reduces neural drive to the phrenic motor pool, impairing ventilatory-related diaphragm activity with incomplete spontaneous recovery. Signaling via the tropomyosin receptor kinase B (TrkB) and glutamatergic transmission through N-methyl-d-aspartate receptors (NMDA-R) have been implicated in this recovery, but whether injury-related changes in TrkB and NMDA-R mRNA expression are uniform across phrenic motor neurons (PhMNs) remains unknown. We hypothesized that TrkB and NMDA-R mRNA transcript number or density would show size- and side-dependent regulation after C2SH.RNAscope was used to quantify the number and density of TrkB and NMDA-R mRNA transcripts in PhMNs ipsilateral and contralateral to C2SH in adult male rats. In mixed linear models with animal as a random effect, there was no effect of PhMN surface area, spinal cord side relative to C2SH or experimental group on TrkB or NMDA-R mRNA transcript number per PhMN. Interaction effects showed TrkB mRNA transcript number increased after C2SH, predominantly ipsilaterally and at larger PhMNs by 21 days post-C2SH (21DSH). Within individual PhMNs, concurrent increases in TrkB and NMDA-R mRNA transcript number were evident by 21DSH. Results were concordant for TrkB and NMDA-R mRNA density within motor neurons. These findings suggest size- and side-dependent changes in TrkB and NMDA-R mRNA regulation within the phrenic motor pool after C2SH, consistent with motor unit–specific plasticity that may contribute to spontaneous respiratory recovery after cervical SCI.
