Faecalibacterium prausnitzii Attenuates CKD via Butyrate-Renal GPR43 Axis.

BACKGROUND: Despite available clinical management strategies, chronic kidney disease (CKD) is associated with severe morbidity and mortality worldwide, which beckons new solutions. Host-microbial interactions with a depletion of Faecalibacterium prausnitzii in CKD are reported. However, the mechanisms about if and how F prausnitzii can be used as a probiotic to treat CKD remains unknown. METHODS: We evaluated the microbial compositions in 2 independent CKD populations for any potential probiotic. Next, we investigated if supplementation of such probiotic in a mouse CKD model can restore gut-renal homeostasis as monitored by its effects on suppression on renal inflammation, improvement in gut permeability and renal function. Last, we investigated the molecular mechanisms underlying the probiotic-induced beneficial outcomes. RESULTS: We observed significant depletion of Faecalibacterium in the patients with CKD in both Western (n=283) and Eastern populations (n=75). Supplementation of F prausnitzii to CKD mice reduced renal dysfunction, renal inflammation, and lowered the serum levels of various uremic toxins. These are coupled with improved gut microbial ecology and intestinal integrity. Moreover, we demonstrated that the beneficial effects in kidney induced by F prausnitzii-derived butyrate were through the GPR (G protein-coupled receptor)-43. CONCLUSIONS: Using a mouse CKD model, we uncovered a novel beneficial role of F prausnitzii in the restoration of renal function in CKD, which is, at least in part, attributed to the butyrate-mediated GPR-43 signaling in the kidney. Our study provides the necessary foundation to harness the therapeutic potential of F prausnitzii for ameliorating CKD.

Minocycline and Pyrrolidine Dithiocarbamate Attenuate Hypertension via Suppressing Activation of Microglia in the Hypothalamic Paraventricular Nucleus.

Proinflammatory cytokines, reactive oxygen species and imbalance of neurotransmitters are involved in the pathophysiology of angiotensin II-induced hypertension. The hypothalamic paraventricular nucleus (PVN) plays a vital role in hypertension. Evidences show that microglia are activated and release proinflammatory cytokines in angiocardiopathy. We hypothesized that angiotensin II induces PVN microglial activation, and the activated PVN microglia release proinflammatory cytokines and cause oxidative stress through nuclear factor-kappa B (NF-κB) pathway, which contributes to sympathetic overactivity and hypertension. Male Sprague-Dawley rats (weight 275-300 g) were infused with angiotensin II to induce hypertension. Then, rats were treated with bilateral PVN infusion of microglial activation inhibitor minocycline, NF-κB activation inhibitor pyrrolidine dithiocarbamate or vehicle for 4 weeks. When compared to control groups, angiotensin II-induced hypertensive rats had higher mean arterial pressure, PVN proinflammatory cytokines, and imbalance of neurotransmitters, accompanied with PVN activated microglia. These rats also had more PVN gp91phox (source of reactive oxygen species production), and NF-κB p65. Bilateral PVN infusion of minocycline or pyrrolidine dithiocarbamate partly or completely ameliorated these changes. This study indicates that angiotensin II-induced hypertensive rats have more activated microglia in PVN, and activated PVN microglia release proinflammatory cytokines and result in oxidative stress, which contributes to sympathoexcitation and hypertensive response. Suppression of activated PVN microglia by minocycline or pyrrolidine dithiocarbamate attenuates inflammation and oxidative stress, and improves angiotensin II-induced hypertension, which indicates that activated microglia promote hypertension through activated NF-κB. The findings may offer hypertension new strategies.

Beneficial effects of metformin supplementation in hypothalamic paraventricular nucleus and arcuate nucleus of type 2 diabetic rats.

Background Oxidative stress and inflammation play important roles in the development of diabetes. Metformin (MET) is considered as the first-line therapy for patients with type 2 diabetes (T2D). Hypothalamic paraventricular nucleus (PVN) and hypothalamic arcuate nucleus (ARC) are vital in obesity and diabetes. However, there have been few studies on the effects of MET on inflammatory reaction and oxidative stress in the PVN and ARC of T2D diabetic rats. Methods Male Sprague-Dawley (SD) rats were fed with high-fat diet (HFD), and intraperitoneally injected with low-dose streptozotocin (STZ, 30 mg/kg) at 6th week to induce T2D diabetes. After injection of STZ, they were fed with HFD continually. Starting from the 8th week of HFD feeding, T2D rats received intragastrical administration of MET (150 mg/kg/day) in addition to the HFD for another 8 weeks. At the end of the 15th week, the rats were anaesthetized to record the sympathetic nerve activity and collect blood and tissue samples. Results In comparison with control rats, T2D diabetic rats had higher levels of pro-inflammatory cytokines (PICs) and excessive oxidative stress in the PVN and ARC, accompanied with more activated astrocytes. The renal sympathetic nerve activity (RSNA) and the plasma norepinephrine (NE) increased in T2D diabetic rats. The expression of tyrosine hydroxylase (TH) increased and the expression of 67-kDa isoform of glutamate decarboxylase (GAD67) decreased in T2D diabetic rats. Supplementation of MET decreased blood glucose, suppressed RSNA, decreased PICs (TNF-α, IL-1ß and IL-6) in PVN and ARC, attenuated oxidative stress and activation of astrocytes in ARC and PVN of T2D diabetic rats, as well as restored the balance of neurotransmitter synthetase. The number of Fra-LI (chronic neuronal excitation marker) positive neurons in the ARC and PVN of T2D diabetic rats increased. Chronic supplementation of MET also decreased the number of Fra-LI positive neurons in the ARC and PVN of T2D diabetic rats. Conclusion These findings suggest that the PVN and ARC participate in the beneficial effects of MET in T2D diabetic rats, which is possibly mediated via down-regulating of inflammatory molecules, attenuating oxidative stress and restoring the balance of neurotransmitter synthetase by MET in the PVN and ARC.

Curcumin ameliorates hypertension via gut-brain communication in spontaneously hypertensive rat.

Gut dysbiosis and dysregulation of gut-brain communication have been identified in hypertensive patients and animal models. Previous studies have shown that probiotic or prebiotic treatments exert positive effects on the pathophysiology of hypertension. This study aimed to examine the hypothesis that the microbiota-gut-brain axis is involved in the antihypertensive effects of curcumin, a potential prebiotic obtained from Curcuma longa. Male 8- to 10-week-old spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats were divided into four groups: WKY rats and SHRs treated with vehicle and SHRs treated with curcumin in dosage of 100 or 300 mg/kg/day for 12 weeks. Our results show that the elevated blood pressure of SHRs was markedly decreased in both curcumin-treated groups. Curcumin treatment also altered the gut microbial composition and improved intestinal pathology and integrity. These factors were associated with reduced neuroinflammation and oxidative stress in the hypothalamus paraventricular nucleus (PVN). Moreover, curcumin treatment increased butyrate levels in the plasma, which may be the result of increased butyrate-producing gut microorganisms. In addition, curcumin treatment also activated G protein-coupled receptor 43 (GPR 43) in the PVN. These results indicate that curcumin reshapes the composition of the gut microbiota and ameliorates the dysregulation of the gut-brain communication to induce antihypertensive effects.

Chronic Infusion of Astaxanthin Into Hypothalamic Paraventricular Nucleus Modulates Cytokines and Attenuates the Renin-Angiotensin System in Spontaneously Hypertensive Rats.

ABSTRACT: Oxidative stress, the renin-angiotensin system (RAS), and inflammation are some of the mechanisms involved in the pathogenesis of hypertension. The aim of this study is to examine the protective effect of the chronic administration of astaxanthin, which is extracted from the shell of crabs and shrimps, into hypothalamic paraventricular nucleus (PVN) in spontaneously hypertensive rats. Animals were randomly assigned to 2 groups and treated with bilateral PVN infusion of astaxanthin or vehicle (artificial cerebrospinal fluid) through osmotic minipumps (Alzet Osmotic Pumps, Model 2004, 0.25 µL/h) for 4 weeks. Spontaneously hypertensive rats had higher mean arterial pressure and plasma level of norepinephrine and proinflammatory cytokine; higher PVN levels of reactive oxygen species, NOX2, NOX4, IL-1ß, IL-6, ACE, and AT1-R; and lower PVN levels of IL-10 and Cu/Zn SOD, Mn SOD, ACE2, and Mas receptors than Wistar-Kyoto rats. Our data showed that chronic administration of astaxanthin into PVN attenuated the overexpression of reactive oxygen species, NOX2, NOX4, inflammatory cytokines, and components of RAS within the PVN and suppressed hypertension. The present results revealed that astaxanthin played a role in the brain. Our findings demonstrated that astaxanthin had protective effect on hypertension by improving the balance between inflammatory cytokines and components of RAS.

Inhibition of miR-135a-5p attenuates vascular smooth muscle cell proliferation and vascular remodeling in hypertensive rats.

Proliferation of vascular smooth muscle cells (VSMCs) greatly contributes to vascular remodeling in hypertension. This study is to determine the roles and mechanisms of miR-135a-5p intervention in attenuating VSMC proliferation and vascular remodeling in spontaneously hypertensive rats (SHRs). MiR-135a-5p level was raised, while fibronectin type III domain-containing 5 (FNDC5) mRNA and protein expressions were reduced in VSMCs of SHRs compared with those of Wistar-Kyoto rats (WKYs). Enhanced VSMC proliferation in SHRs was inhibited by miR-135a-5p knockdown or miR-135a-5p inhibitor, but exacerbated by miR-135a-5p mimic. VSMCs of SHRs showed reduced myofilaments, increased or even damaged mitochondria, increased and dilated endoplasmic reticulum, which were attenuated by miR-135a-5p inhibitor. Dual-luciferase reporter assay shows that FNDC5 was a target gene of miR-135a-5p. Knockdown or inhibition of miR-135a-5p prevented the FNDC5 downregulation in VSMCs of SHRs, while miR-135a-5p mimic inhibited FNDC5 expressions in VSMCs of both WKYs and SHRs. FNDC5 knockdown had no significant effects on VSMC proliferation of WKYs, but aggravated VSMC proliferation of SHRs. Exogenous FNDC5 or FNDC5 overexpression attenuated VSMC proliferation of SHRs, and prevented miR-135a-5p mimic-induced enhancement of VSMC proliferation of SHR. MiR-135a-5p knockdown in SHRs attenuated hypertension, normalized FNDC5 expressions and inhibited vascular smooth muscle proliferation, and alleviated vascular remodeling. These results indicate that miR-135a-5p promotes while FNDC5 inhibits VSMC proliferation in SHRs. Silencing of miR-135a-5p attenuates VSMC proliferation and vascular remodeling in SHRs via disinhibition of FNDC5 transcription. Either inhibition of miR-135a-5p or upregulation of FNDC5 may be a therapeutically strategy in attenuating vascular remodeling and hypertension.

Interleukin-1ß in hypothalamic paraventricular nucleus mediates excitatory renal reflex.

Chemical stimulation of kidney causes sympathetic activation and pressor responses in rats. The excitatory renal reflex (ERR) is mediated by angiotensin type 1 receptor (AT1R) and superoxide anions in hypothalamic paraventricular nucleus (PVN). The aim of this study is to determine whether interleukin-1ß (IL-1ß) in the PVN mediates the ERR, and whether the IL-1ß production in the PVN is dependent on the AT1R-superoxide anion signaling. Experiments were performed in adult rats under anesthesia. The ERR was induced by renal infusion of capsaicin, and evaluated by the responses of the contralateral renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP). Inhibition of IL-1ß production with MCC950 in the PVN dose-dependently inhibited the capsaicin-induced ERR and sympathetic activation. The PVN microinjection of IL-1 receptor antagonist IL-1Ra or specific IL-1ß antibody abolished the capsaicin-induced ERR, while IL-1ß enhanced the ERR. Renal infusion of capsaicin promoted p65-NFκB phosphorylation and IL-1ß production in the PVN, which were prevented by PVN microinjection of NADPH oxidase inhibitor apocynin or the superoxide anion scavenger tempol. The PVN microinjection of NFκB inhibitor BMS-345541 abolished the capsaicin induced-ERR and IL-1ß production, but not the NADPH oxidase activation and superoxide anion production. Furthermore, capsaicin-induced p65-NFκB phosphorylation and IL-1ß production in the PVN were prevented by AT1R antagonist losartan, or angiotensin converting enzyme inhibitor captopril. These results indicate that capsaicin-induced ERR and sympathetic activation are mediated by IL-1ß in the PVN. The IL-1ß production in the PVN is dependent on the AT1R-mediated superoxide anion generation and NFκB activation.

Calcitriol ameliorated autonomic dysfunction and hypertension by down-regulating inflammation and oxidative stress in the paraventricular nucleus of SHR.

The hypothalamic paraventricular nucleus (PVN) plays crucial roles in central cardiovascular regulation. Increasing evidence in humans and rodents shows that vitamin D intake is important for achieving optimal cardiovascular function. The purpose of this study was to investigate whether calcitriol, an active form of vitamin D, improves autonomic and cardiovascular function in hypertensive rats and whether PVN oxidative stress and inflammation are involved in these beneficial effects. Male spontaneously hypertensive rats (SHR) and normotensive control Wistar Kyoto (WKY) rats were treated with either calcitriol (40 ng/day) or vehicle (0.11 µL/h) through chronic PVN infusion for 4 weeks. Blood pressure and heart rate were recorded continuously by radiotelemetry. PVN tissue, heart and plasma were collected for molecular and histological analysis. Compared to WKY rats, SHR exhibited increased systolic blood pressure, sympathetic drive, and cardiac hypertrophy and remodeling. These were associated with higher mRNA and protein expression levels of high mobility box 1 (HMGB1), receptor for advanced glycation end products (RAGE), toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), proinflammatory cytokines, NADPH oxidase subunit in the PVN. In addition, increased norepinephrine in plasma, elevated reactive oxygen species levels and activation of microglia in the PVN were also observed in SHR. Chronic calcitriol treatment ameliorated these changes but not in WKY rats. Our results demonstrate that chronic infusion of calcitriol in the PVN ameliorates hypertensive responses, sympathoexcitation and retains cardiovascular function in SHR. Reduced inflammation and oxidative stress within the PVN are involved in these calcitriol-induced effects.

Irisin lowers blood pressure by activating the Nrf2 signaling pathway in the hypothalamic paraventricular nucleus of spontaneously hypertensive rats.

Exercise training is one of the major non-pharmacological treatments for hypertension. However, the central mechanism by which exercise training attenuates the hypertensive responses remains unclear. Irisin is a muscle-secreted cytokine derived from fibronectin type III domain containing 5 (FNDC5) that will be released into the circulation during exercise. We hypothesized that irisin may play a role in the blood pressure regulation by exercise. To examine the hypothesis, our study investigated the effect of irisin on hypertension and its central mechanism. The study was performed in spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto rats. We found that intravenous injection of irisin effectively reduced blood pressure, plasma norepinephrine, paraventricular nucleus (PVN) levels of neuronal activation, oxidative stress and inflammation in SHRs. Moreover, irisin activated nuclear factor E2-related factor-2 (Nrf2) and restored the imbalance of neurotransmitters in the PVN. Our study also found PVN knockdown of Nrf2 abolished the protective effects of irisin on hypertension. These findings demonstrate irisin can improve hypertension via Nrf2-mediated antioxidant in the PVN.

Inhibition of Hypothalamic Inhibitor κB Kinase ß/Nuclear Transcription Factor κB Pathway Attenuates Metabolism and Cardiac Dysfunction in Type 2 Diabetic Rats.

BACKGROUND: Inflammation and oxidative stress play important roles in energy imbalance and its complications. Recent research indicates that hypothalamic inflammation may contribute to the pathogenesis of metabolic syndrome and cardiac dysfunction, but the mechanisms remain unclear. We hypothesized that suppression of the proinflammatory IKKß/NF-κB pathway in the hypothalamus can improve energy balance and cardiac function in type 2 diabetic (T2D) rats. METHODS: Normal and T2D rats received bilateral hypothalamic arcuate nucleus (ARC) infusions of the IKKß inhibitor SC-514 or vehicle via osmotic minipump. Metabolic phenotyping, immunohistochemical analyses, and biochemical analyses were used to investigate the outcomes of inhibition of the hypothalamic IKKß. Echocardiography and glucometer were used for measuring cardiac function and blood glucose, respectively. Blood samples were collected for the evaluation of circulating proinflammatory cytokines. Heart was harvested for cardiac morphology evaluations. The ARC was harvested and analyzed for IKKß, NF-κB, proinflammatory cytokines, reactive oxygen species (ROS), and NAD(P)H (gp91phox, p47phox) oxidase activity levels and neuropeptides. RESULTS: Compared with normal rats, T2D rats were characterized by hyperglycemia, hyperinsulinemia, glucose intolerance, cardiac dysfunction, as well as higher ARC levels of IKKß, NF-κB, proinflammatory cytokines, ROS, gp91phox, and p47phox. ARC infusion of the IKKß inhibitor SC-514 attenuated all these changes in T2D rats, but not in normal rats. CONCLUSIONS: Our results indicate that the hypothalamic IKKß/NF-κB pathway plays a key role in modulating energy imbalance and cardiac dysfunction, suggesting its potential therapeutic role during type 2 diabetes mellitus.

Infusion of Melatonin Into the Paraventricular Nucleus Ameliorates Myocardial Ischemia-Reperfusion Injury by Regulating Oxidative Stress and Inflammatory Cytokines.

Melatonin, the receptors for which are abundant in the hypothalamic paraventricular nucleus (PVN), can protect the heart from myocardial ischemia-reperfusion (MI/R) injury. The aim of this study was to determine whether the infusion of melatonin into the PVN protects the heart from MI/R injury by suppressing oxidative stress or regulating the balance between proinflammatory cytokines and anti-inflammatory cytokines in MI/R rats. Male Sprague-Dawley rats were treated with a bilateral PVN infusion of melatonin. MI/R operation was performed 1 week after infusion. At the end of the third week after the infusion, all the rats were euthanized. This was followed by immunohistochemistry and immunofluorescence studies of the rats. MI/R rats showed larger infarct size, increased left ventricular (LV) end-diastolic volume, and decreased LV ejection fraction and LV fractional shortening. Moreover, MI/R rats had a higher level of norepinephrine in the plasma, heart, and PVN; higher PVN levels of reactive oxygen species, NOX2, NOX4, IL-1ß, and NF-κB activity; and lower PVN levels of copper/zinc superoxide dismutase (Cu/Zn-SOD) and IL-10 compared with the sham group. Melatonin infusion in PVN reduced LV end-diastolic volume, norepinephrine, reactive oxygen species, NOX2, NOX4, IL-1ß, and NF-κB activity, and increased LV ejection fraction, LV fractional shortening, Cu/Zn-SOD, and IL-10. Overall, these results suggest that the infusion of melatonin ameliorates sympathetic nerve activity and MI/R injury by attenuating oxidative stress and inflammatory cytokines in the PVN of MI/R rats.

Exercise Training Attenuates Proinflammatory Cytokines, Oxidative Stress and Modulates Neurotransmitters in the Rostral Ventrolateral Medulla of Salt-Induced Hypertensive Rats.

BACKGROUND/AIMS: Exercise training (ExT) was associated with cardiovascular diseases including hypertension. The rostral ventrolateral medulla (RVLM) is a key region for central control of blood pressure and sympathetic nerve activity. Therefore, this study aimed to investigate the mechanisms within RVLM that can influence exercise training induced effects in salt-induced hypertension. METHODS: Male Wistar rats were fed with a normal salt (0.3%) (NS) or a high salt (8%) (HS) diet for 12 weeks to induce hypertension. Then these rats were given moderate-intensity ExT for a period of 12 weeks. RVLM was used to determine glutamate and gamma-aminobutyric acid (HPLC), phosphorylated IKKß, Fra-LI, 67-kDa isoform of glutamate decarboxylase (GAD67), proinflammatory cytokines (PIC) and NADPH-oxidase (NOX) subunits expression (Immunohistochemistry and Immunofluorescence, Western blotting). PIC and NF-κB p65 activity in the plasma were evaluated by ELISA studies. Renal sympathetic nerve activity (RSNA) was recorded and analyzed using the PowerLab system. RESULTS: High salt diet resulted in increased mean arterial pressure and cardiac hypertrophy. These high salt diet rats had higher RVLM levels of glutamate, PIC, phosphorylated IKKß, NF-κB p65 activity, Fra-LI, superoxide, NOX-2 (gp91phox) and 4, and lower RVLM levels of gamma-aminobutyric acid and GAD67, and higher plasma levels of PIC, norepinephrine, and higher RSNA. ExT attenuated these changes in salt-induced hypertensive rats. CONCLUSIONS: These findings suggest that high salt diet increases the activity of NF-κB and the levels of PIC and oxidative stress, and induces an imbalance between excitatory and inhibitory neurotransmitters in the RVLM. ExT attenuates hypertension and cardiac hypertrophy partially mediated by attenuating oxidative stress and modulating neurotransmitters in the RVLM.

Fibronectin Type III Domain-Containing 5 Attenuates Liver Fibrosis Via Inhibition of Hepatic Stellate Cell Activation.

BACKGROUND/AIMS: Fibronectin type III domain-containing 5 (FNDC5) protein is involved in the beneficial effects of exercise on metabolism. FNDC5 attenuates hepatic steatosis induced by high fat diet (HFD). Here, we examined the effects of FNDC5 on liver fibrosis and underline mechanisms. METHODS: Experiments were carried out on wild-type and FNDC5-/- mice, primary mouse hepatic stellate cells (HSCs) and human hepatic stellate cell line (LX-2). The mice were fed with HFD for 6 months to induce liver fibrosis. Oxidized low density lipoprotein (oxLDL) were used to induce the activation of hepatic stellate cells and fibrosis in mouse HSCs and human LX-2 cells. H&E, Masson's trichrome staining and Sirius red staining were used for liver sections. Protein and mRNA expressions were evaluated with Western blot and RT-PCR, respectively. RESULTS: FNDC5 deficiency aggravated the HFD-induced liver fibrosis and HSCs activation in mice. It exacerbated the HFD-induced inhibition of AMPK phosphorylation, upregulation of connective tissue growth factor (CTGF) and transforming growth factor-ß (TGF-ß), and deposition of extracellular matrix (ECM) in liver of mice. Administration of FNDC5 attenuated oxLDL-induced AMPK deactivation, HSCs activation, CTGF and TGF-ß upregulation and ECM deposition in mouse HSCs. The beneficial effects of FNDC5 on oxLDL-induced AMPK dephosphorylation, HSCs activation and ECM deposition were prevented by the inhibition of AMPK with compound C in human LX-2 cells. However, the effects of FNDC5 on hepatic fibrosis in vivo in this study cannot be distinguished from its effects on adiposity and hepatic steatosis. CONCLUSIONS: FNDC5 deficiency aggravates HFD-induced liver fibrosis in mice. FNDC5 plays beneficial roles in attenuating liver fibrosis via AMPK phosphorylation-mediated inhibition of HSCs activation.

Central blockade of NLRP3 reduces blood pressure via regulating inflammation microenvironment and neurohormonal excitation in salt-induced prehypertensive rats.

BACKGROUND: Inflammation has been implicated in the development of cardiovascular disease. We determined whether nod-like receptor with pyrin domain containing 3 (NLRP3) involved in the process of prehypertension, central blockade of NLRP3 decreased inflammation reaction, regulated neurohormonal excitation, and delayed the progression of prehypertension. METHODS: Prehypertensive rats were induced by 8% salt diet. The rats on high-salt diet for 1 month were administered a specific NLRP3 blocker in the hypothalamic paraventricular nucleus (PVN) for 4 weeks. ELISA, western blotting, immunohistochemistry, and flow cytometry were used to measure NLRP3 cascade proteins, pro-inflammation cytokines (PICs), chemokine ligand 2 (CCL2), C-X-C chemokine receptor type 3 (CXCR3), vascular cell adhesion molecule 1 (VCAM-1), neurotransmitters, and leukocytes count detection, respectively. RESULTS: NLRP3 expression in PVN was increased significantly in prehypertensive rats, accompanied by increased number of microglia, CD4+, CD8+ T cell, and CD8+ microglia. Expressions of PICs, CCL2, CXCR3, and VCAM-1 significantly increased. The balance between 67-kDa isoform of glutamate decarboxylase (GAD67) and tyrosine hydroxylase (TH) was damaged. Plasma norepinephrine (NE) in prehypertensive rats was increased and gamma-aminobutyric acid (GABA) was reduced. NLRP3 blockade significantly decreased blood pressure, reduced PICs, CCL2, VCAM-1 expression in PVN, and restored neurotransmitters. Blood pressure and inflammatory markers were upregulated after termination of central blockage NLRP3. CONCLUSIONS: Salt-induced prehypertension is partly due to the role of NLRP3 in PVN. Blockade of brain NLRP3 attenuates prehypertensive response, possibly via downregulating the cascade reaction triggered by inflammation and restoring the balance of neurotransmitters.

Anti-GABAB receptor encephalitis in a patient with gastric adenocarcinoma.

Anti-γ-aminobutyric acid-B (GABAB) receptor encephalitis is an autoimmune encephalitis associated with antibodies against neuronal cell surface antigens, which are primarily observed with small-cell lung cancer, melanoma, and thymoma. Here, we first report a case on the association between a relatively frequent cancer, gastric adenocarcinoma (GAC), and a rare GABAB receptor antibody limbic encephalitis. The patient was treated with immunotherapy and combined-drug chemotherapy, which were partially effective in terms of stabilizing the tumor and relieving neurological symptoms. This report indicates that, when patients present with GABAB receptor antibody limbic encephalitis, regular and broad screening for tumors including gastric adenocarcinoma should also be considered.

Progressive Reduction in Myocyte Autophagy After Myocardial Infarction in Rabbits: Association with Oxidative Stress and Left Ventricular Remodeling.

BACKGROUND/AIMS: The alterations in myocyte autophagy after myocardial infarction (MI) and the underlying mechanisms have not been fully understood. In this study, we investigated the temporal changes of myocyte autophagy in the remote non-infarcted myocardium in rabbits after MI and the relationships between alterations of myocyte autophagy and left ventricular (LV) remodeling and myocardial oxidative stress. METHODS: Rabbits were assigned to MI or sham operation. Rabbits with MI or sham were randomly assigned to receive chloroquine, an autophagy inhibitor, antioxidant vitamins C and E or placebo for 4 weeks. H9C2 cardiomyocytes were subjected to hypoxia or hydrogen peroxide (H2O2) treatment. RESULTS: MI rabbits exhibited progressive increases of LV end-diastolic dimension (EDD), and decreases of LV fractional shortening (FS) and dP/dt over 8 weeks. Myocyte autophagy assessed by the scores of LC3 and Beclin1 expression was progressively decreased at 1, 4 and 8 weeks after MI. The ratio of LC3 II/I and Beclin1 and Atg5 proteins were also decreased at 4 weeks after MI. There was a negative correlation between autophagy and LV EDD and a positive correlation between autophagy and LV FS and dP/dt. The autophagy inhibitor chloroquine worsened LV remodeling after MI. Decreased myocyte autophagy was associated with increased myocardial 4-hydroxynonenal. Antioxidant vitamins C and E prevented the decrease in myocyte autophagy after MI. In cultured H9C2 cardiomyocytes, the LC3 II/I ratio was decreased at 4 and 8 h after exposure to hypoxia, and the change was associated with increased 8-hydroxy-2-deoxyguanosine. A low concentration of H2O2 decreased the LC3 II/I ratio. CONCLUSION: Progressive reduction in myocyte autophagy in the remote non-infarcted myocardium was associated with myocardial oxidative stress and LV remodeling after MI. Antioxidants prevented the reduction in myocyte autophagy after MI, suggesting that oxidative stress mediates reduction in myocyte autophagy that contributes to post-MI remodeling.

NLRP3 Gene Deletion Attenuates Angiotensin II-Induced Phenotypic Transformation of Vascular Smooth Muscle Cells and Vascular Remodeling.

BACKGROUND/AIMS: Angiotensin (Ang) II plays vital roles in vascular inflammation and remodeling in hypertension. Phenotypic transformation of vascular smooth muscle cells (VSMCs) is a major initiating factor for vascular remodeling. The present study was designed to determine the roles of NLRP3 inflammasome activation in Ang II-induced VSMC phenotypic transformation and vascular remodeling in hypertension. METHODS: Primary VSMCs from the aorta of NLRP3 knockout (NLRP3-/-) mice and wild-type (WT) mice were treated with Ang II for 24 h. Subcutaneous infusion of Ang II via osmotic minipump for 2 weeks was used to induce vascular remodeling and hypertension in WT and NLRP3-/- mice. RESULTS: NLRP3 gene deletion attenuates Ang II-induced NLRP3 inflammasome activation, phenotypic transformation from a contractile phenotype to a synthetic phenotype and proliferation in primary mice VSMCs. Ang II-induced hypertension and vascular remodeling in WT mice were attenuated in NLRP3-/- mice. Furthermore, Ang II-induced NLRP3 inflammasome activation, phenotypic transformation and proliferating cell nuclear antigen (PCNA) upregulation were inhibited in the media of aorta of NLRP3-/- mice. CONCLUSIONS: NLRP3 inflammasome activation contributes to Ang II-induced VSMC phenotypic transformation and proliferation as well as vascular remodeling and hypertension.

Central administration of tert-butylhydroquinone attenuates hypertension via regulating Nrf2 signaling in the hypothalamic paraventricular nucleus of hypertensive rats.

Reactive oxygen species (ROS) in the paraventricular nucleus (PVN) play a pivotal role in the pathogenesis of hypertension. Nuclear factor E2-related factor-2 (Nrf2) is an important transcription factor that modulates cell antioxidant defense response against oxidative stress. The present study aimed to explore the efficacy of PVN administration of tert-butylhydroquinone (tBHQ), a selective Nrf2 activator, in hypertensive rats. 16-week-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were used in this study. These rats were chronic bilateral PVN infusion of tBHQ (0.8µg/day), or oxygen free radical scavenger tempol (20µg/h), or vehicle for 2weeks. SHR rats had higher mean arterial pressure (MAP), plasma norepinephrine (NE) levels, and sympathetic nerve activity (RSNA) and lower PVN levels of Nrf2, hemeoxygenase-1 (HO-1), superoxide dismutase-1 (SOD1) and catalase (CAT) as compared with those in the WKY group. Bilateral PVN infusion of tBHQ or tempol significantly reduced MAP, RSNA, plasma NE levels in SHR rats. In addition, tBHQ treatment enhanced the nuclear accumulation of Nrf2 and increased the expression of HO-1, CAT and SOD1 in SHR rats. Furthermore, tBHQ attenuated PVN levels of ROS, the expression of proinflammatory cytokines and restored the imbalance of neurotransmitters in PVN. Knockdown of Nrf2 in the PVN by adeno-associated virus mediated small interfering RNA abrogated the protective effects of tBHQ on hypertension. These findings suggest that PVN administration of tBHQ can attenuate hypertension by activation of the Nrf2-mediated signaling pathway.

FNDC5 overexpression and irisin ameliorate glucose/lipid metabolic derangements and enhance lipolysis in obesity.

Irisin is a cleaved and secreted fragment of fibronectin type III domain containing 5 (FNDC5), and contributes to the beneficial effects of exercise on metabolism. Here we report the therapeutical effects of FNDC5/irisin on metabolic derangements and insulin resistance in obesity, and show the lipolysis effect of irisin and its signal molecular mechanism. In obese mice, lentivirus mediated-FNDC5 overexpression enhanced energy expenditure, lipolysis and insulin sensitivity, and reduced hyperlipidemia, hyperglycemia, hyperinsulinism, blood pressure and norepinephrine levels; it increased hormone-sensitive lipase (HSL) expression and phosphorylation, and reduced perilipin level and adipocyte diameter in adipose tissues. Subcutaneous perfusion of irisin reduced hyperlipidemia and hyperglycemia, and improved insulin resistance. Either FNDC5 overexpression or irisin perfusion only induced a tendency toward a slight decrease in body weight in obese mice. In 3T3-L1 adipocytes, irisin enhanced basal lipolysis rather than isoproterenol-induced lipolysis, which were prevented by inhibition of adenylate cyclase or PKA; irisin increased the HSL and perilipin phosphorylation; it increased PKA activity, and cAMP and HSL mRNA levels, but reduced perilipin expression. These results indicate that FNDC5/irisin ameliorates glucose/lipid metabolic derangements and insulin resistance in obese mice, and enhances lipolysis via cAMP-PKA-HSL/perilipin pathway. FNDC5 or irisin can be taken as an effective therapeutic strategy for metabolic disorders.

Salusin-ß contributes to vascular remodeling associated with hypertension via promoting vascular smooth muscle cell proliferation and vascular fibrosis.

Vascular smooth muscle cell (VSMC) proliferation and vascular fibrosis are closely linked with hypertension and atherosclerosis. Salusin-ß is a bioactive peptide involved in the pathogenesis of atherosclerosis. However, it is still largely undefined whether salusin-ß is a potential candidate in the VSMC proliferation and vascular fibrosis. Experiments were carried out in human vascular smooth muscle cells (VSMCs) and in rats with intravenous injection of lentivirus expressing salusin-ß. In vitro, salusin-ß promoted VSMCs proliferation, which was attenuated by adenylate cyclase inhibitor SQ22536, PKA inhibitor Rp-cAMP, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478, ERK inhibitor U0126 or cAMP response element binding protein (CREB) inhibitor KG501. It promoted the phosphorylation of ERK1/2, CREB and EGFR, which were abolished by SQ22536 or Rp-cAMP. Furthermore, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478 diminished the salusin-ß-evoked ERK1/2 and CREB phosphorylation. On the other hand, salusin-ß increased collagen-I, collagen-III, fibronectin and connective tissue growth factor (CTGF) mRNA and phosphorylation of Smad2/3, which were prevented by ALK5 inhibitor A83-01. In vivo, salusin-ß overexpression increased the media thickness, media/lumen ratio coupled with ERK1/2, CREB, EGFR and Smad2/3 phosphorylation, as well as the mRNA of collagen-I, collagen-III, fibronectin, transforming growth factor-ß1 (TGF-ß1) and CTGF in arteries. Moreover, salusin-ß overexpression in rats caused severe hypertension. Intravenous injection of salusin-ß dose-relatedly increased blood pressure, but excessive salusin-ß decreased blood pressure and heart rate. These results indicate that salusin-ß promotes VSMC proliferation via cAMP-PKA-EGFR-CREB/ERK pathway and vascular fibrosis via TGF-ß1-Smad pathway. Increased salusin-ß contributes to vascular remodeling and hypertension.