Intervention of asprosin attenuates oxidative stress and neointima formation in vascular injury.

AIMS: Asprosin, a newly discovered hormone, is linked to insulin resistance. This study shows the roles of asprosin in vascular smooth muscle cells (VSMCs) proliferation, migration, oxidative stress and neointima formation of vascular injury. METHODS: Mouse aortic VSMCs were cultured, and platelet-derived growth factor-BB (PDGF-BB) was used to induce oxidative stress, proliferation and migration in VSMCs. Vascular injury was induced by repeatedly moving a guidewire in the lumen of carotid artery in mice. RESULTS: Asprosin overexpression promoted VSMC oxidative stress, proliferation and migration, which were attenuated by toll-like receptor 4 (TLR4) knockdown, antioxidant NAC, NOX1 inhibitor ML171 or NOX2 inhibitor GSK2795039. Asprosin overexpression increased NOX1/2 expressions, while asprosin knockdown increased heme oxygenase-1 (HO-1) and NADPH quinone oxidoreductase-1 (NQO-1) expressions. Asprosin inhibited Nrf2 nuclear translocation. Nrf2 activator sulforaphane increased HO-1 and NQO-1 expressions, and prevented asprosin-induced NOX1/2 upregulation, oxidative stress, proliferation and migration. Exogenous asprosin protein had similar roles to asprosin overexpression. PDGF-BB increased asprosin expressions. PDGF-BB-induced oxidative stress, proliferation and migration were enhanced by Nrf2 inhibitor ML385, but attenuated by asprosin knockdown. Vascular injury increased asprosin expression. Local asprosin knockdown in the injured carotid artery promoted HO-1 and NQO-1 expressions, but attenuated the NOX1 and NOX2 upregulation, oxidative stress, neointima formation and vascular remodeling in mice. INNOVATION AND CONCLUSION: Asprosin promotes oxidative stress, proliferation and migration of VSMCs via TLR4-Nrf2-mediated redox imbalance. Inhibition of asprosin expression attenuates VSMC proliferation and migration, oxidative stress and neointima formation in the injured artery. Asprosin might be a promising therapeutic target for vascular injury.

Dexmedetomidine Attenuates Lipopolysaccharide-Induced Sympathetic Activation and Sepsis via Suppressing Superoxide Signaling in Paraventricular Nucleus.

Sympathetic overactivity contributes to the pathogenesis of sepsis. The selective α2-adrenergic receptor agonist dexmedetomidine (DEX) is widely used for perioperative sedation and analgesia. We aimed to determine the central roles and mechanisms of DEX in attenuating sympathetic activity and inflammation in sepsis. Sepsis was induced by a single intraperitoneal injection of lipopolysaccharide (LPS) in rats. Effects of DEX were investigated 24 h after injection of LPS. Bilateral microinjection of DEX in the paraventricular nucleus (PVN) attenuated LPS-induced sympathetic overactivity, which was attenuated by the superoxide dismutase inhibitor DETC, cAMP analog db-cAMP or GABAA receptor antagonist gabazine. Superoxide scavenger tempol, NADPH oxidase inhibitor apocynin, adenylate cyclase inhibitor SQ22536 or PKA inhibitor Rp-cAMP caused similar effects to DEX in attenuating LPS-induced sympathetic activation. DEX inhibited LPS-induced superoxide and cAMP production, as well as NADPH oxidase, adenylate cyclase and PKA activation. The roles of DEX in reducing superoxide production and NADPH oxidase activation were attenuated by db-cAMP or gabazine. Intravenous infusion of DEX inhibited LPS-induced sympathetic overactivity, NOX activation, superoxide production, TNF-α and IL-1ß upregulation in the PVN and plasma, as well as lung and renal injury, which were attenuated by the PVN microinjection of yohimbine and DETC. We conclude that activation of α2-adrenergic receptors with DEX in the PVN attenuated LPS-induced sympathetic overactivity by reducing NADPH oxidase-dependent superoxide production via both inhibiting adenylate cyclase-cAMP-PKA signaling and activating GABAA receptors. The inhibition of NADPH oxidase-dependent superoxide production in the PVN partially contributes to the roles of intravenous infusion of DEX in attenuating LPS-induced sympathetic activation, oxidative stress and inflammation.

Salusin-ß in Intermediate Dorsal Motor Nucleus of the Vagus Regulates Sympathetic-Parasympathetic Balance and Blood Pressure.

The dorsal motor nucleus of the vagus (DMV) is known to control vagal activity. It is unknown whether the DMV regulates sympathetic activity and whether salusin-ß in the DMV contributes to autonomic nervous activity. We investigated the roles of salusin-ß in DMV in regulating sympathetic-parasympathetic balance and its underline mechanisms. Microinjections were carried out in the DMV and hypothalamic paraventricular nucleus (PVN) in male adult anesthetized rats. Renal sympathetic nerve activity (RSNA), blood pressure and heart rate were recorded. Immunohistochemistry for salusin-ß and reactive oxidative species (ROS) production in the DMV were examined. Salusin-ß was expressed in the intermediate DMV (iDMV). Salusin-ß in the iDMV not only inhibited RSNA but also enhanced vagal activity and thereby reduced blood pressure and heart rate. The roles of salusin-ß in causing vagal activation were mediated by NAD(P)H oxidase-dependent superoxide anion production in the iDMV. The roles of salusin-ß in inhibiting RSNA were mediated by not only the NAD(P)H oxidase-originated superoxide anion production in the iDMV but also the γ-aminobutyric acid (GABA)A receptor activation in PVN. Moreover, endogenous salusin-ß and ROS production in the iDMV play a tonic role in inhibiting RSNA. These results indicate that salusin-ß in the iDMV inhibits sympathetic activity and enhances vagal activity, and thereby reduces blood pressure and heart rate, which are mediated by NAD(P)H oxidase-dependent ROS production in the iDMV. Moreover, GABAA receptor in the PVN mediates the effect of salusin-ß on sympathetic inhibition. Endogenous salusin-ß and ROS production in the iDMV play a tonic role in inhibiting sympathetic activity.

Extracellular vesicle-mediated miR135a-5p transfer in hypertensive rat contributes to vascular smooth muscle cell proliferation via targeting FNDC5.

Background Extracellular vesicles (EVs) from vascular adventitial fibroblasts (AFs) contribute to the proliferation of vascular smooth muscle cells (VSMCs) and vascular remodeling in spontaneously hypertensive rat (SHR). This study shows the crucial roles of EVs-mediated miR135a-5p transfer in VSMC proliferation and the underlying mechanisms in hypertension. Methods AFs and VSMCs were obtained from the aorta of Wistar-Kyoto rat (WKY) and SHR. EVs were isolated from the culture of AFs with ultracentrifugation method. Results MiR135a-5p level in SHR-EVs was significantly increased. MiR135a-5p inhibitor prevented the SHR-EVs-induced VSMC proliferation. Fibronectin type III domain containing 5 (FNDC5) was a target gene of miR135a-5p. FNDC5 level was lower in VSMCs of SHR. MiR135a-5p inhibitor not only increased FNDC5 expression, but reversed the SHR-EVs-induced FNDC5 downregulation in VSMCs of SHR. MiR135a-5p mimic inhibited FNDC5 expression, but failed to promote the SHR-EVs-induced FNDC5 downregulation in VSMCs of SHR. Exogenous FNDC5 prevented the SHR-EVs-induced VSMC proliferation of both WKY and SHR. Knockdown of miR135a-5p in fibroblasts completely prevented the upregulation of miR135a-5p in the EVs. The SHR-EVs from the miR135a-5p knockdown-treated fibroblasts lost their roles in inhibiting FNDC5 expression and promoting proliferation in VSMCs of both WKY and SHR. Conclusions Increased miR135a-5p in the SHR-EVs promoted VSMC proliferation of WKY and SHR via inhibiting FNDC5 expression. MiR135a-5p and FNDC5 are crucial targets for intervention of VSMC proliferation in hypertension.

Activation of mTOR in the spinal cord is required for pain hypersensitivity induced by chronic constriction injury in mice.

BACKGROUND: The mammalian target of rapamycin (mTOR) is known to regulate cell growth, and it also participates in pain transmission as has been recently verified in inflammatory and neuropathic pain models. The targeting of mTOR represents a new strategy for the control of chronic pain. In the present study, we investigated the effect of mTOR in the expression of PSD95 and NR2B-PSD95 or GluA2-PSD95 interaction ratio in a chronic constriction injury (CCI) mice model. METHODS: Paw mechanical withdrawal threshold (PMWT) and paw withdrawal thermal latency (PWTL) were respectively used to assess mechanical allodynia and thermal hyperalgesia after CCI operation and intrathecal injection of rapamycin. Western blot and co-immunoprecipitation were used to investigate the effects of rapamycin on the expression of PSD95 and interaction ratio of NR2B-PSD95 or GluA2-PSD95 in the spinal dorsal horn of mice. RESULTS: Our study demonstrated that the inhibition of spinal mTOR with intrathecal injections of rapamycin (1 µg/5 µL) for days 1-6 after CCI surgery led to an obvious decrease in CCI-induced neuropathic pain. Rapamycin significantly reduced the PMWT of CCI mice, whereas there was no significant effect on PWTL. The active form of the mTOR signaling pathway (p-mTOR, p-4EBP1 and p-p70S6k) at the spinal level remarkably increased in CCI mice, and rapamycin could inhibit this up-regulation. The increased expression of PSD95 and the interaction ratio of GluA2-PSD95 or NR2B-PSD95 could also be inhibited by intrathecal injection of rapamycin. CONCLUSION: These data suggest that the mTOR pathway is activated in the spinal dorsal horn in CCI-induced neuropathic pain, and the intrathecal injection of rapamycin can reduce mechanical allodynia. Our findings indicate that spinal mTOR is an important component of CCI-induced neuropathic pain, and mTOR may be a potential target for chronic pain therapy.