Inhibition of NF-κB activity in the hypothalamic paraventricular nucleus attenuates hypertension and cardiac hypertrophy by modulating cytokines and attenuating oxidative stress

Activation AMPK in Hypothalamic Paraventricular Nucleus Improves Renovascular Hypertension Through ERK1/2-NF-κB Pathway

Hypertension is a globally prevalent disease, but the pathogenesis remains largely unclear. AMP-activated protein kinase (AMPK) is a nutrition-sensitive signal of cellular energy metabolism, which has a certain influence on the development of hypertension. Previously, we found a down-regulation of the phosphorylated (p-) form of AMPK, and the up-regulation of the angiotensin II type 1 receptor (AT1-R) and that of p-ERK1/2 in the hypothalamic paraventricular nucleus (PVN) of hypertensive rats. However, the exact mechanism underlying the relationship between AMPK and AT1-R in the PVN during hypertension remains unclear. Thus, we hypothesized that AMPK modulates AT1-R through the ERK1/2-NF-κB pathway in the PVN, thereby inhibiting sympathetic nerve activity and improving hypertension. To examine this hypothesis, we employed a renovascular hypertensive animal model developed via two-kidney, one-clip (2K1C) and sham-operated (SHAM). Artificial cerebrospinal fluid (aCSF), used as vehicle, or 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR, an AMPK activator, 60 μg/day) was microinjected bilaterally in the PVN of these rats for 4 weeks. In 2K1C rats, there an increase in systolic blood pressure (SBP) and circulating norepinephrine (NE). Also, the hypertensive rats had lowered expression of p-AMPK and p-AMPK/AMPK, elevated expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R, increased NF-κB p65 activity in the PVN compared with the levels of these biomarkers in SHAM rats. Four weeks of bilateral PVN injection of AMPK activator AICAR, attenuated the NE level and SBP, increased the expression of p-AMPK and p-AMPK/AMPK, lessened the NF-κB p65 activity, decreased the expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R in the PVN of 2K1C rats. Data from this study imply that the activation of AMPK within the PVN suppressed AT1-R expression through inhibiting the ERK1/2-NF-κB pathway, decreased the activity of the sympathetic nervous system, improved hypertension.

Testis-Specific Protein, Y-Encoded-Like 2 Activates JAK2/STAT3 Pathway in Hypothalamic Paraventricular Nucleus to Sustain Hypertension

BACKGROUND

In the hypothalamic paraventricular nucleus (PVN) of spontaneously hypertensive rats (SHRs), the expression of the testis-specific protein, Y-encoded-like 2 (TSPYL2) and the phosphorylation level of Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) are higher comparing with the normotensive Wistar Kyoto rats (WKY). But how they are involved in hypertension remains unclear. TSPYL2 may interact with JAK2/STAT3 in PVN to sustain high blood pressure during hypertension.

METHODS

Knockdown of TSPYL2 via adeno-associated virus (AAV) carrying shRNA was conducted through bilateral microinjection into the PVN of SHR and WKY rats. JAK2/STAT3 inhibition was achieved by intraperitoneally or PVN injection of AG490 into the SHRs. Blood pressure (BP), plasma norepinephrine (NE), PVN inflammatory response, and PVN oxidative stress were measured.

RESULTS

TSPYL2 knock-down in the PVN of SHRs but not WKYs led to reduced BP and plasma NE, deactivation of JAK2/STAT3, decreased expression of pro-inflammatory cytokine IL-1β, and increased expression of anti-inflammatory cytokine IL-10 in the PVN. Meanwhile, AG490 administrated in both ways reduced the BP in the SHRs and deactivated JAK2/STAT3 but failed to change the expression of TSPYL2 in PVN. AG490 also downregulated expression of IL-1β and upregulated expression of IL-10. Both knockdown of TSPYL2 and inhibition of JAK2/STAT3 can reduce the oxidative stress in the PVN of SHRs.

CONCLUSION

JAK2/STAT3 is regulated by TSPYL2 in the PVN of SHRs, and PVN TSPYL2/JAK2/STAT3 is essential for maintaining high BP in hypertensive rats, making it a potential therapeutic target for hypertension.

Research progress on the protective effect of hormones and hormone drugs in myocardial ischemia-reperfusion injury

Ischemic heart disease (IHD) is a condition where the heart muscle does not receive enough blood flow, leading to cardiac dysfunction. Restoring blood flow to the coronary artery is an effective clinical therapy for myocardial ischemia. This strategy helps lower the size of the myocardial infarction and improves the prognosis of patients. Nevertheless, if the disrupted blood flow to the heart muscle is restored within a specific timeframe, it leads to more severe harm to the previously deprived heart tissue. This condition is referred to as myocardial ischemia/reperfusion injury (MIRI). Until now, there is a dearth of efficacious strategies to prevent and manage MIRI. Hormones are specialized substances that are produced directly into the circulation by endocrine organs or tissues in humans and animals, and they have particular effects on the body. Hormonal medications utilize human or animal hormones as their active components, encompassing sex hormones, adrenaline medications, thyroid hormone medications, and others. While several studies have examined the preventive properties of different endocrine hormones, such as estrogen and hormone analogs, on myocardial injury caused by ischemia-reperfusion, there are other hormone analogs whose mechanisms of action remain unexplained and whose safety cannot be assured. The current study is on hormones and hormone medications, elucidating the mechanism of hormone pharmaceuticals and emphasizing the cardioprotective effects of different endocrine hormones. It aims to provide guidance for the therapeutic use of drugs and offer direction for the examination of MIRI in clinical therapy.

The Regulatory Effect of the Paraventricular Nucleus on Hypertension

Hypertension is among the most harmful factors of cardiovascular and cerebrovascular diseases and poses an urgent problem for the development of human society. In addition to previous studies on its pathogenesis focusing on the peripheral sympathetic nervous system, investigating the central causes of high blood pressure involving the neuroendocrine and neuroinflammatory mechanisms of the hypothalamic paraventricular nucleus (PVN) is paramount. This nucleus is considered to regulate the output of neurohormones and sympathetic nerve activity. In this article, we focussed on the neuroendocrine mechanism, primarily exploring the specific contributions and interactions of various neurons and neuroendocrine hormones, including GABAergic and glutamatergic neurons, nitric oxide, arginine vasopressin, oxytocin, and the renin-angiotensin system. Additionally, the neuroinflammatory mechanism in the PVN was discussed, encompassing microglia, reactive oxygen species, inflammatory factors, and pathways, as well as immune connections between the brain and extracerebral organs. Notably, the two central mechanisms involved in the PVN not only exist independently but also communicate with each other, jointly maintaining the hypertensive state of the body. Furthermore, we introduce well-known molecules and signal transduction pathways within the PVN that can play a regulatory role in the two mechanisms to provide a basis and inspire ideas for further research.

Role of blood-borne factors in sympathoexcitation-mediated hypertension: Potential neurally mediated hypertension in preeclampsia

Hypertension remains a threat for society due to its unknown causes, preventing proper management, for the growing number of patients, for its state as a high-risk factor for stroke, cardiac and renal complication and as cause of disability. Data from clinical and animal researches have suggested the important role of many soluble factors in the pathophysiology of hypertension through their neuro-stimulating effects. Central targets of these factors are of molecular, cellular and structural nature. Preeclampsia (PE) is characterized by high level of soluble factors with strong pro-hypertensive activity and includes immune factors such as proinflammatory cytokines (PICs). The potential neural effect of those factors in PE is still poorly understood. Shedding light into the potential central effect of the soluble factors in PE may advance our current comprehension of the pathophysiology of hypertension in PE, which will contribute to better management of the disease. In this paper, we summarized existing data in respect of hypothesis of this review, that is, the existence of the neural component in the pathophysiology of the hypertension in PE. Future studies would address this hypothesis to broaden our understanding of the pathophysiology of hypertension in PE.

Identification of Key Genes from the Visceral Adipose Tissues of Overweight/Obese Adults with Hypertension through Transcriptome Sequencing

Overweight and obese (OW/OB) adults are at increased risk of hypertension due to visceral adipose tissue (VAT) inflammation. In this study, we explored gene level differences in the VAT of hypertensive and normotensive OW/OB patients. VAT samples obtained from six OW/OB adults (three hypertensive, three normotensive) were subjected to transcriptome sequencing analysis. Gene set enrichment analysis was conducted for all gene expression data to identify differentially expressed genes (DEGs) with |log2 (fold change)| ≥ 1 and q < 0.05. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analyses were performed on the DEGs, and hub genes were identified by constructing a protein-protein interaction (PPI) network. The proposed hub genes were validated using quantitative real-time PCR in ten other samples from five hypertensive and five normotensive patients. In addition, we performed ROC analysis and Spearman correlation analysis. A total of 84 DEGs were identified between VAT samples from OW/OB patients with and without hypertension, among which 21 were significantly upregulated and 63 were significantly downregulated. Bioinformatics analysis revealed that spleen function was related to hypertension in OW/OB adults. Meanwhile, PPI network analysis identified the following top 10 hub genes: CD79A, CR2, SELL, CD22, IL7R, CCR7, TNFRSF13C, CXCR4, POU2AF1, and JAK3. Through qPCR verification, we found that CXCR4, CD22, and IL7R were statistically significant. qPCR verification suggested that RELA was statistically significant. However, qPCR verification indicated that NFKB1 and KLF2 were not statistically significant. These hub genes were mainly regulated by the transcription factor RELA. The AUC of ROC analysis for CXCR4, IL7R, and CD22 was 0.92. What is more, VAT CXCR4 and CD22 were positively related to RELA relative expression levels. Taken together, our research demonstrates that CXCR4, IL7R, and CD22 related to VAT in hypertensive OW/OB adults could serve as future therapeutic targets.

Genistein Alleviates Oxidative Stress and Inflammation in the Hypothalamic Paraventricular Nucleus by Activating the Sirt1/Nrf2 Pathway in High Salt-Induced Hypertension

Hypertension caused by a high-salt (HS) diet is one of the major causes of cardiovascular diseases. Underlining pathology includes oxidative stress and inflammation in the hypothalamic paraventricular nucleus (PVN). This study investigates genistein's (Gen) role in HS-induced hypertension and the underlying molecular mechanism. We placed male Wistar rats on HS (8% NaCl) or normal salt diet (0.3% NaCl). Then, we injected bilateral PVN in rats with Gen, vehicle, or nicotinamide (NAM) for 4 weeks. Tail cuff was used weekly to assess the systolic pressure, diastolic pressure, and mean arterial pressure (MAP). Cardiac hypertrophy was analyzed by heart weight/body weight ratio and wheat germ agglutinin staining. ELISA kits, Western blot, or dihydroethidium staining determined the levels of inflammatory cytokines and oxidative stress markers. Western blot measured protein levels of Sirt1, Ac-FOXO1, Nrf2, NQO-1, HO-1, and gp91^phox. Our result showed that PVN infusion of Gen significantly reduced the increase of systolic pressure, diastolic pressure, and MAP induced by an HS diet. Additionally, there was a decrease in cardiac hypertrophy and the levels of inflammatory cytokines in PVN and plasma. Meanwhile, PVN infusion of Gen notably inhibited the levels of oxidized glutathione and superoxide dismutase and improved the glutathione level and total antioxidant capacities and superoxide dismutase activities. It also decreased the level of reactive oxygen species and gp91^phox expression in PVN. Furthermore, Gen infusion markedly increases the Sirt1, Nrf2, HO-1, and NQO-1 levels and decreases the Ac-FOXO1 level. However, PVN infusion of NAM could significantly block these changes induced by Gen in HS diet rats. Our results demonstrated that PVN infusion of Gen could inhibit the progression of hypertension induced by an HS diet by activating the Sirt1/Nrf2 pathway.

Exercise Training Attenuates Hypertension via Suppressing ROS/MAPK/NF-κB/AT-1R Pathway in the Hypothalamic Paraventricular Nucleus

Background: Aerobic exercise training (ExT) is beneficial for hypertension, however, its central mechanisms in improving hypertension remain unclear. Since the importance of the up-regulation of angiotensin II type 1 receptor (AT-1R) in the paraventricular nucleus (PVN) of the hypothalamic in sympathoexcitation and hypertension has been shown, we testified the hypothesis that aerobic ExT decreases blood pressure in hypertensive rats by down-regulating the AT-1R through reactive oxygen species (ROS)/mitogen-activated protein kinase (MAPK)/nuclear factors κB (NF-κB) pathway within the PVN. Methods: Forty-eight male Sprague-Dawley (SD) rats were assigned to the following groups: sham operation (SHAM) + kept sedentary (Sed), SHAM + exercise training (ExT), two kidney-one clamp (2K1C) + Sed, and 2K1C + ExT groups. Results: The 2K1C + Sed hypertensive rats showed higher systolic blood pressure (SBP), upregulated ROS, phosphorylated (p-) p44/42 MAPK, p-p38 MAPK, NF-κB p65 activity, and AT-1R expression in the PVN, and increased circulating norepinephrine (NE) than those of SHAM rats. After eight weeks of aerobic ExT, the 2K1C + ExT hypertensive rats showed attenuated NE and SBP levels, suppressed NF-κB p65 activity, and reduced expression of ROS, p-p44/42 MAPK, p-p38 MAPK, and AT-1R in the PVN, relatively to the 2K1C + Sed group. Conclusions: These data are suggestive of beneficial effects of aerobic ExT in decreasing SBP in hypertensive rats, via down-regulating the ROS/MAPK/NF-κB pathway that targets AT-1R in the PVN, and eventually ameliorating 2K1C-induced hypertension.

Astaxanthin Ameliorates Blood Pressure in Salt-Induced Prehypertensive Rats Through ROS/MAPK/NF-κB Pathways in the Hypothalamic Paraventricular Nucleus

Astaxanthin (AST) has a variety of biochemical effects, including anti-inflammatory, antioxidative, and antihypertensive functions. The aim of the present study was to determine whether AST ameliorates blood pressure in salt-induced prehypertensive rats by ROS/MAPK/NF-κB pathways in hypothalamic paraventricular nucleus.To explore the central effects of AST on the development of blood pressure, prehypertensive rats were induced by a high-salt diet (HS, 8% NaCl) and its control groups were treated with normal-salt diet (NS, 0.3% NaCl). The Dahl salt-sensitive (S) rats with HS diet for 6 weeks received AST or vehicle by gastric perfusion for 6 weeks. Compared to those with NS diet, rats with HS diet exhibited increased mean arterial pressure (MAP) and heart rate (HR). These increases were associated with higher plasma level of norepinephrine (NE), interleukin 1β (IL-1β), and interleukin 6 (IL-6); elevated PVN level of reactive oxygen species (ROS), NOX2, and NOX4, that of IL-1β, IL-6, monocyte chemotactic protein 1 (MCP-1), tyrosine hydroxylase (TH), phosphorylation extracellular-signal-regulated kinase (p-ERK1/2), phosphorylation Jun N-terminal kinases (p-JNK), nuclear factor-kappa B (NF-κB) activity; and lower levels of IL-10, superoxide dismutase (SOD), and catalase (CAT) in the PVN. In addition, our data demonstrated that chronic AST treatment ameliorated these changes in the HS but not NS diet rats. These data suggested that AST could alleviate prehypertensive response in HS-induced prehypertension through ROS/MAPK/NF-κB pathways in the PVN.

Long-term inhibition of UCHL1 decreases hypertension and retinopathy in spontaneously hypertensive rats

OBJECTIVE

To investigate the role of the deubiquitinase ubiquitin C-terminal hydrolase L1 (UCHL1) in hypertension and retinopathy in the spontaneously hypertensive rat (SHR).

METHODS

Wistar-Kyoto (WKY) rats and SHRs were administered the UCHL1 inhibitor LDN57444 (20 μg/kg/day) for 4 months. Pathological changes were detected with hematoxylin and eosin, immunofluorescence, and dihydroethidium staining. The mRNA and protein expression of UCHL1 were examined by real-time PCR and immunoblotting analysis.

RESULTS

At 6 months of age, SHRs showed significantly increased mRNA and protein levels of UCHL1 in the retina compared with WKY rats. Moreover, SHRs exhibited significantly increased central retinal thickness, inflammation, and reactive oxygen species production compared with WKY rats, and these effects were markedly attenuated by systemic administration of the UCHL1 inhibitor LDN57444. The beneficial effects of LDN57444 were possibly associated with reduced blood pressure and the inactivation of several signaling pathways.

CONCLUSION

UCHL1 is involved in hypertension and retinopathy in SHRs, suggesting that UCHL1 may be used as a potential therapeutic target for treating hypertensive retinopathy.

Vascular Inflammation in Hypertension: Targeting Lipid Mediators Unbalance and Nitrosative Stress

Arterial hypertension is a worldwide public health threat. High Blood Pressure (BP) is commonly associated with endothelial dysfunction, nitric oxide synthases (NOS) unbalance and high peripheral vascular resistance. In addition to those, inflammation has also been designated as one of the major components of BP increase and organ damage in hypertension. This minireview discusses vascular inflammatory triggers of high BP and aims to fill the existing gaps of antiinflammatory therapy of hypertension. Among the reasons discussed, enhanced prostaglandins rather than resolvins lipid mediators, immune cell infiltration and oxidative/nitrosative stress are pivotal players of BP increase within the inflammatory hypothesis. To address these inflammatory targets, this review also proposes new concepts in hypertension treatment with non-steroidal antiinflammatory drugs (NSAIDs), nitric oxide-releasing NSAIDs (NO-NSAIDs) and specialized proresolving mediators (SPM). In this context, the failure of NSAIDs in hypertension treatment seems to be associated with the reduction of endogenous NO bioavailability, which is not necessarily an effect of all drug members of this pharmacological class. For this reason, NO-releasing NSAIDs seem to be safer and more specific therapy to treat vascular inflammation in hypertension than regular NSAIDs.

Nrf1 Knock-Down in the Hypothalamic Paraventricular Nucleus Alleviates Hypertension Through Intervention of Superoxide Production-Removal Balance and Mitochondrial Function

Oxidative stress in the hypothalamic paraventricular nucleus (PVN) contributes greatly to the development of hypertension. The recombinant nuclear respiratory factor 1 (Nrf1) regulates the transcription of several genes related to mitochondrial respiratory chain function or antioxidant expression, and thus may be involved in the pathogenesis of hypertension. Here we show that in the two-kidney, one-clip (2K1C) hypertensive rats the transcription level of Nrf1 was elevated comparing to the normotensive controls. Knocking down of Nrf1 in the PVN of 2K1C rats can significantly reduce their blood pressure and level of plasma norepinephrine (NE). Analysis revealed significant reduction of superoxide production level in both whole cell and mitochondria, along with up-regulation of superoxide dismutase 1 (Cu/Zn-SOD), NAD(P)H: quinone oxidoreductase 1 (NQO1), thioredoxin-dependent peroxiredoxin 3 (Prdx3), cytochrome c (Cyt-c) and glutathione synthesis rate-limiting enzyme (glutamyl-cysteine ligase catalytic subunit (Gclc) and modifier subunit (Gclm)), and down-regulation of cytochrome c oxidase subunit VI c (Cox6c) transcription after Nrf1 knock-down. In addition, the reduced ATP production and elevated mitochondrial membrane potential in the PVN of 2K1C rats were reinstated with Nrf1 knock-down, together with restored expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitochondrial transcription factor A (Tfam), coiled-coil myosin-like BCL2-interacting protein (Beclin1), and Mitofusin 1 (Mfn1), which are related to the mitochondrial biogenesis, fusion, and autophagy. Together, the results indicate that the PVN Nrf1 is associated with the development of 2K1C-induced hypertension, and Nrf1 knock-down in the PVN can alleviate hypertension through intervention of mitochondrial function and restorement of the production-removal balance of superoxide.

Effects of irbesartan on phenotypic alterations in monocytes and the inflammatory status of hypertensive patients with left ventricular hypertrophy

Background

Circulating monocytes and tissue macrophages play complex roles in the pathogenesis of hypertension and the resulting target organ damage. In this study, we observed alterations in the monocyte phenotype and inflammatory state of hypertensive patients with left ventricular hypertrophy (LVH) and studied the effects of irbesartan in these patients. This study might reveal a novel mechanism by which irbesartan alleviates LVH, and it could provide new targets for the prevention and treatment of hypertensive target organ damage.

Methods

CD163 and CD206 expression on monocytes and IL-10 and TNF-α levels in the serum of hypertensive patients with or without LVH and of healthy volunteers were detected. Furthermore, we treated monocytes from the LVH group with different concentrations of irbesartan, and then, CD163, CD206, IL-10 and TNF-α expression was detected.

Results

We found, for the first time, that the expression of CD163, CD206 and IL-10 in the LVH group was lower than that in the non-LVH group and healthy control group, but the TNF-α level in the LVH group was significantly higher. Irbesartan upregulated the expression of CD163 and CD206 in hypertensive patients with LVH in a concentration-dependent manner. Irbesartan also increased the expression of IL-10 and inhibited the expression of TNF-α in monocyte culture supernatants in a concentration-dependent manner.

Conclusions

Our data suggest that inflammation was activated in hypertensive patients with LVH and that the monocyte phenotype was mainly proinflammatory. The expression of proinflammatory factors increased while the expression of anti-inflammatory factors decreased. Irbesartan could alter the monocyte phenotype and inflammatory status in hypertensive patients with LVH. This previously unknown mechanism may explain how irbesartan alleviates LVH.

Trail registration The study protocols were approved by the Ethical Committee of the Second Affiliated Hospital of Dalian Medical University. Each patient signed the informed consent form.

Activation of Paraventricular Melatonin Receptor 2 Mediates Melatonin-Conferred Cardioprotection Against Myocardial Ischemia/Reperfusion Injury

Previous studies have shown that melatonin (Mel) can effectively ameliorate myocardial ischemia/reperfusion (MI/R) injury, but the mechanism is yet to be fully elucidated. Mel receptors are expressed in the paraventricular nucleus (PVN), which is also involved in regulating cardiac sympathetic nerve activity. The aim of this study was to examine whether Mel receptors in the PVN are involved in the protective effects of Mel against MI/R injury. The results of quantitative polymerase chain reaction, western blot, and immunofluorescence assays indicated that Mel receptor 2 (MT2) expression in the PVN was upregulated after MI/R. Intraperitoneal administration of Mel significantly improved post-MI/R cardiac function and reduced the infarct size, whereas shRNA silencing of MT2 in the PVN partially blocked this effect. Intraperitoneal administration of Mel reduced sympathetic nerve overexcitation caused by MI/R, whereas shRNA silencing of MT2 in the PVN partially diminished this effect. Furthermore, enzyme-linked immunosorbent assay and western blot results indicated that intraperitoneal administration of Mel lowered the levels of inflammatory cytokines in the PVN after MI/R injury, whereas the application of sh-MT2 in the PVN reduced this effect of Mel. Mel significantly reduced the levels of NF-κB after astrocyte oxygen and glucose deprivation/reoxygenation injury, and this effect was offset when MT2 was silenced. The above experimental results suggest that MT2 in the PVN partially mediated the protective effects of Mel against MI/R injury, and its underlying mechanisms may be related to postactivation amelioration of PVN inflammation and reduction of cardiac sympathetic nerve overexcitation.

Altered Gut Microbiota is Involved in the Anti-Hypertensive Effects of Vitamin C in Spontaneously Hypertensive Rat

SCOPE

Gut dysbiosis and dysregulation of the gut-brain-axis contributes to the pathogenesis of hypertension. Vitamin C (VC) is a common dietary supplement that shows the ability to lower the elevated blood pressure in hypertensive animals. Thus, the hypothesis that the gut microbiota is involved in the anti-hypertensive effect of VC is proposed.

METHODS AND RESULTS

The changes of the gut microbiota and pathology in a spontaneously hypertensive rat (SHR) model after daily oral intake of VC in dosage of 200 or 1000 mg kg-1 are examined. After 4 weeks, the elevated blood pressure of SHRs in both VC-treated groups is attenuated. Sequencing of the gut microbiota shows improvement in its diversity and abundance. Bioinformatic analysis suggests restored metabolism and biosynthesis-related functions of the gut, which are confirmed by the improvement of gut pathology and integrity. Analysis of the hypothalamus paraventricular nucleus (PVN), the central pivot of blood pressure regulation, also shows reduced inflammatory responses and oxidative stress.

CONCLUSIONS

The reduced blood pressure, enriched gut microbiota, improved gut pathology and integrity, and reduced inflammatory responses and oxidative stress in the PVN together suggest that the anti-hypertensive effects of VC involve reshaping of gut microbiota composition and function.

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-1β, 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.

Exercise and food supplement of vitamin C ameliorate hypertension through improvement of gut microflora in the spontaneously hypertensive rats

AIMS

Exercise and food supplement of vitamin C (VC) are beneficial to human health, especially for those who suffer from hypertension. Here we tend to explore if gut microflora is involved in the anti-hypertensive effects of exercise and VC-supplement therapies.

MATERIALS AND METHODS

With the spontaneously hypertensive rat (SHR) model, the small intestine pathology and the fecal microbiota was analyzed along with the pro- and anti-inflammatory cytokines (PICs and AICs) and reactive oxygen species (ROS) in the hypothalamus paraventricular nucleus (PVN) and intestine.

KEY FINDINGS

We found that both exercise and VC intake, individually or combined, were able to alleviate the blood pressure in the SHRs comparing to the normotensive control Wistar-kyoto (WKY) rats. The expression level of PICs in the PVN and intestine of the SHRs was down-regulated while the AICs were up-regulated after treatments, together with down-regulation of ROS in the PVN. At meantime, the gut pathology was dramatically improved in the SHRs with exercise training or VC intake. Analysis of the gut microflora revealed significant changes in their composition. Several important micro-organisms that were deficient in the SHRs were found up-regulated by the treatments, including Turicibacter and Romboutsia which are involved in the short-chain fatty acid production.

SIGNIFICANCE

Exercise training and VC intake individually can modify the gut microflora composition and improve the inflammatory state in both PVN and intestine, which contribute to their anti-hypertensive function. Combination of the two treatments enhanced their effects and worth to be considered as a non-medical aid for the hypertensive patients.

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-1β, 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-1β, 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.

Attenuation of the inflammatory response and polarization of macrophages by photobiomodulation

In spinal cord injury (SCI), inflammation is a major mediator of damage and loss of function and is regulated primarily by the bone marrow-derived macrophages (BMDMs). Photobiomodulation (PBM) or low-level light stimulation is known to have anti-inflammatory effects and has previously been used in the treatment of SCI, although its precise cellular mechanisms remain unclear. In the present study, the effect of PBM at 810 nm on classically activated BMDMs was evaluated to investigate the mechanisms underlying its anti-inflammatory effects. BMDMs were cultured and irradiated (810 nm, 2 mW/cm²) following stimulation with lipopolysaccharide and interferon-γ. CCK-8 assay, 2',7'-dichlorofluorescein diacetate assay, and ELISA and western blot analysis were performed to measure cell viability, reactive oxygen species production, and inflammatory marker production, respectively. PBM irradiation of classically activated macrophages significantly increased the cell viability and inhibited reactive oxygen species generation. PBM suppressed the expression of a marker of classically activated macrophages, inducible nitric oxide synthase; decreased the mRNA expression and secretion of pro-inflammatory cytokines, tumor necrosis factor alpha, and interleukin-1 beta; and increased the secretion of monocyte chemotactic protein 1. Exposure to PBM likewise significantly reduced the expression and phosphorylation of NF-κB p65 in classically activated BMDMs. Taken together, these results suggest that PBM can successfully modulate inflammation and polarization in classically activated BMDMs. The present study provides a theoretical basis to support wider clinical application of PBM in the treatment of SCI.

Inhibition of Hypothalamic Inhibitor κB Kinase β/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 IKKβ/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 IKKβ 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 IKKβ. 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 IKKβ, 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 IKKβ, NF-κB, proinflammatory cytokines, ROS, gp91phox, and p47phox. ARC infusion of the IKKβ inhibitor SC-514 attenuated all these changes in T2D rats, but not in normal rats.

CONCLUSIONS

Our results indicate that the hypothalamic IKKβ/NF-κB pathway plays a key role in modulating energy imbalance and cardiac dysfunction, suggesting its potential therapeutic role during type 2 diabetes mellitus.

Superoxide anions modulate the performance of apelin in the paraventricular nucleus on sympathetic activity and blood pressure in spontaneously hypertensive rats

The present study was designed to determine how apelin in paraventricular nucleus (PVN) modulates the renal sympathetic nerve activity (RSNA), arterial blood pressure (ABP), mean arterial pressure (MAP), and heart rate (HR), and whether superoxide anions regulate the performance of PVN apelin in spontaneously hypertensive rats (SHRs). Acute experiment was carried out with 13-week-old male Wistar-Kyoto rats (WKY) and SHRs under anaesthesia. RSNA, ABP, MAP and HR after PVN microinjection were measured. Apelin microinjection into PVN increased RSNA, ABP, MAP and HR in WKY rats and SHRs, more obviously in SHRs. APJ antagonist F13A decreased the RSNA, ABP, MAP and HR in SHRs, and inhibited the effects of apelin. Apelin and APJ mRNA levels were higher in the PVN in SHRs. PVN microinjection of superoxide anion scavengers tempol and tiron, or NAD(P)H oxidase inhibitor apocynin, decreased the RSNA, ABP, MAP and HR in SHRs, and inhibited the effects of apelin, but the superoxide dismutase (SOD) inhibitor diethyldithiocarbamic acid (DETC) potentiated the effects of apelin. NAD(P)H oxidase activity and superoxide anion levels in PVN were increased by apelin, but decreased by APJ antagonist F13A. The apelin-induced increases in NAD(P)H oxidase activity and superoxide anion level were abolished by pre-treatment with F13A. These results indicate that apelin in PVN increases the sympathetic outflow and blood pressure via activating APJ receptor. The enhanced activity of endogenous apelin and APJ receptor in PVN contributes to sympathetic activation in hypertension, and the superoxide anion is involved in these apelin-mediated processes in PVN.

Interaction among inflammasome, autophagy and non-coding RNAs: new horizons for drug

Autophagy and inflammasomes are shown to interact in various situations including infectious disease, cancer, diabetes and neurodegeneration. Since multiple layers of molecular regulators contribute to the interplay between autophagy and inflammasome activation, the detail of such interplay remains largely unknown. Non-coding RNAs (ncRNAs), which have been implicated in regulating an expanding list of cellular processes including immune defense against pathogens and inflammatory response in cancer and metabolic diseases, may join in the crosstalk between inflammasomes and autophagy in physiological or disease conditions. In this review, we summarize the latest research on the interlink among ncRNAs, inflammasomes and autophagy and discuss the emerging role of these three in multiple signaling transduction pathways involved in clinical conditions. By analyzing these intriguing interconnections, we hope to unveil the mechanism inter-regulating these multiple processes and ultimately discover potential drug targets for some refractory diseases.

Crocin attenuates isoprenaline-induced myocardial fibrosis by targeting TLR4/NF-κB signaling: connecting oxidative stress, inflammation, and apoptosis

Crocin is isolated from saffron and has multiple activities. There are many reports on its beneficial effects for cardiovascular disease, but crocin's effects on anti-myocardial fibrosis have not yet been reported. This study investigated crocin's effects and potential mechanisms on isoproterenol (ISO)-induced myocardial fibrosis (MF) in mice. Mice were infused intraperitoneally with crocin with concurrent ISO subcutaneous injections over 2 weeks. Electrocardiography, cardiac weight index (CWI), hydroxyproline content, and heart morphology changes were observed. Administration of crocin markedly decreased heart rate, J-point elevation, QRS interval, CWI, and hydroxyproline content in the myocardial tissues, and improved heart pathologic morphology. Versus the control group, the ISO group showed an increase in lactate dehydrogenase and creatine kinase activities and malondialdehyde content. Meanwhile, superoxide dismutase, catalase, and glutathione contents decreased in the ISO group; crocin caused a significant reduction in oxidative stress levels in ISO-induced MF. ISO led to a significant increase in interleukin-1 and -6 and tumor necrosis factor-α in addition to nuclear factor kappa B (NF-κB) (p65) and toll-like receptor (TLR) 4 expressions. Crocin treatment suppressed these inflammatory cytokine expressions. Moreover, crocin treatment caused a significant decrease in connective tissue growth factor and transforming growth factor-β1 mRNA levels in addition to a decrease in B cell lymphoma-2, Bcl-2-associated X protein, caspase-3, and cleaved caspase-3 expressions. Crocin has a protective effect on ISO-induced MF, which may be associated with the TLR4/NF-κB (p65) signal transduction pathway.

Chemoattraction and Recruitment of Activated Immune Cells, Central Autonomic Control, and Blood Pressure Regulation

Inflammatory mediators play a critical role in the regulation of sympathetic outflow to cardiovascular organs in hypertension. Emerging evidence highlights the involvement of immune cells in the regulation of blood pressure. However, it is still unclear how these immune cells are activated and recruited to key autonomic brain regions to regulate sympathetic outflow to cardiovascular organs. Chemokines such as C-C motif chemokine ligand 2 (CCL2), and pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β), are upregulated both peripherally and centrally in hypertension. More specifically, they are upregulated in key autonomic brain regions that control sympathetic activity and blood pressure such as the paraventricular nucleus of the hypothalamus and the rostral ventrolateral medulla. Furthermore, this upregulation of inflammatory mediators is associated with the infiltration of immune cells to these brain areas. Thus, expression of pro-inflammatory chemokines and cytokines is a potential mechanism promoting invasion of immune cells into key autonomic brain regions. In pathophysiological conditions, this can result in abnormal activation of brain circuits that control sympathetic nerve activity to cardiovascular organs and ultimately in increases in blood pressure. In this review, we discuss emerging evidence that helps explain how immune cells are chemoattracted to autonomic nuclei and contribute to changes in sympathetic outflow and blood pressure.

Pyrrolidine Dithiocarbamate Attenuates Cardiocyte Apoptosis and Ameliorates Heart Failure Following Coronary Microembolization in Rats

Background

Nuclear factor-kB is highly activated in cardiovascular disorders. However, few articles have targeted at the role of nuclear factor-kB inhibitor in heart failure.

Aims

To evaluate the effects of nuclear factor-kB inhibitor pyrrolidine dithiocarbamate on cardiocyte apoptosis and cardiac function in a rat heart failure model.

Study Design

Animal experiment.

Methods

A stable and reproducible rat heart failure model (n=64) was prepared by injecting homologous microthrombotic particles into the left ventricle of Sprague–Dawley rats while obstructing the ascending aorta to produce coronary microembolization. Rats with heart failure were randomized into untreated (HFu) and pyrrolidine dithiocarbamate-treated (HFp) groups; the latter received an intraperitoneal injection of pyrrolidine dithiocarbamate (100 mg/kg/day) 1 h prior to surgery as well as on postoperative days 1-7. The sham group comprised 32 Sprague–Dawley rats. Eight rats from each group were sacrificed on days 1, 3, 7, and 14 postoperatively. Masson’s trichrome staining was used to determine the micro-fibrotic area to indicate the severity of myocardial loss. Terminal transferase uridine triphosphate nick end labeling staining was used to detect apoptotic cardiomyocytes. Echocardiography and hemodynamics were performed to evaluate left ventricular function.

Results

Rats with heart failure exhibited pathological changes evidenced by patchy myocardial fibrosis, remarkably elevated severity of myocardial loss, and persistently reduced left ventricular function. At the end of the study, compared with the HFu group, myocardial infarct size was reduced by 28% (p=0.001), cardiocyte apoptosis was suppressed (7.17%±1.47% vs 2.83%±0.75%, p<0.001), cardiac function parameters such as left ventricular ejection fraction (80%±4% vs 61%±6%), left ventricular + dP/dt max (4828±289 vs 2918±76 mmHg.s−1), left ventricular - dP/dt max (4398±269 vs 2481±365 mmHg.s−1), and left ventricular systolic pressure (126±13 vs 100±10 mmHg) were significantly increased, and left ventricular end-diastolic pressure was reduced (18±2 vs 13±1 mmHg) (p<0.001, for all) in the HFu group.

Conclusion

Our rat model can adequately mimic heart failure via coronary vessel embolization. Moreover, pyrrolidine dithiocarbamate treatment can reduce cardiocyte apoptosis and improve cardiac function, which may be beneficial for patients with heart failure secondary to myocardial infarction.

Sensory plasticity of carotid body is correlated with oxidative stress in paraventricular nucleus during chronic intermittent hypoxia

Chronic intermittent hypoxia (CIH) is known to induce hypertension, but the mechanism is not well understood. We hypothesized that sensory plasticity of the carotid body (CB) and oxidative stress in the paraventricular nucleus (PVN) are involved in CIH-induced hypertension. In this study, rats were exposed to CIH for 28 days (intermittent hypoxia of 21% O₂ for 60 s and 5% O₂ for 30 s, cyclically repeated for 8 hr/day) and then randomly grouped for intracerebroventricular injection of 5-HT2 receptor antagonist ritanserin, Rho-associated protein kinase (ROCK) inhibitor Y-27632, and NADPH oxidase (NOX) inhibitor diphenyleneiodonium (DPI), respectively. We found that CIH increased blood pressure (BP), elevated carotid sinus nerve (CSN) and renal sympathetic nerve (RSN) activities, oxidative stress, and cell apoptosis in PVN. NOX-derived reactive oxygen species (ROS) production and cell apoptosis decreased when CIH-induced activation of 5-HT/5-HT2AR/PKC signaling was inhibited by ritanserin. In addition, RhoA expression was downregulated when oxidative stress was attenuated by DPI, while Y-27632 decreased the expression of endothelin-1, which is overexpressed in the vascular wall during hypertension. Moreover, treatment with ritanserin, DPI or Y-27632 attenuated the sensory plasticity and sympathetic hyperactivity as well as CIH-induced elevation of BP. In conclusion, CIH-induced activation of 5-HT/5-HT2AR/PKC signaling contributes to NOX-derived oxidative stress in PVN, which may cause sensory plasticity of CB, RSN hyperactivity, and elevated BP.

Chronic infusion of berberine into the hypothalamic paraventricular nucleus attenuates hypertension and sympathoexcitation via the ROS/Erk1/2/iNOS pathway

BACKGROUND

Berberine (BBR), a Chinese traditional herbal medicine, has many pharmacologic benefits such as anti-inflammation and anti-oxidation. It is widely used in clinical treatment of cardiovascular diseases such as hypertension. However, the mechanism of how BBR attenuates hypertension through affecting central neural system is not clear.

PURPOSE

This study was designed to determine whether chronic infusion of BBR into the hypothalamic paraventricular nucleus (PVN) attenuates hypertension and sympathoexcitation via the ROS/Erk1/2/iNOS pathway.

METHODS

Two-kidney, one-clip (2K1C) renovascular hypertensive rats were randomly assigned and treated with bilateral PVN infusion of BBR (2μg/h) or vehicle (artificial cerebrospinal fluid) via osmotic minipumps for 28 days.

RESULTS

2K1C rats showed higher mean arterial pressure (MAP) and PVN Fra-like activity, plasma levels of norepinephrine (NE), PVN levels of NOX2, NOX4, Erk1/2 and iNOS, and lower PVN levels of copper/zinc superoxide dismutase (Cu/Zn-SOD). Chronic infusion of BBR reduced MAP, PVN Fra-like activity and plasma levels of NE, reduced NOX2, NOX4, Erk1/2, iNOS and induced Cu/Zn-SOD in the PVN.

CONCLUSIONS

These results suggest that BBR attenuates hypertension and sympathoexcitation via the ROS/Erk1/2/iNOS pathway in 2K1C renovascular hypertensive rats.

Loss of LRRC25 accelerates pathological cardiac hypertrophy through promoting fibrosis and inflammation regulated by TGF-β1

Despite advances in therapeutic strategies, heart failure-associated mortality rates remain high. Thus, understanding the pathophysiological molecular mechanisms involved in the remodeling process is essential for developing new and effective therapies. LRRs are present various prokaryotic and eukaryotic proteins and important for the innate immune system via regulating protein-protein interactions. LRRC25 is a member of leucine-rich repeat (LRR)-containing protein family. LRRC25 has been shown to negatively modulate nuclear factor κB (NF-κB) activation, a crucial factor related to cardiac hypertrophy. Our aim was to explore the effects of LRRC25 on cardiac hypertrophy. In the present study, LRRC25 levels were decreased in human and mouse hypertrophied hearts. LRRC25 knockout exacerbated cardiac hypertrophy responding to pressure overloading or angiotensin II (Ang II) stimulation. Deletion of LRRC25 accelerated cardiac dysfunction and fibrosis in mice subjected to aortic banding (AB). LRRC25 ablation induced a strong increase in the transcription of both hypertrophy (ANP, BNP, and β-MHC) and fibrosis associated molecules (col1, col3a1, α-SMA and fibronectin). In addition, the expression of transforming growth factor-β1 (TGF-β1), and its down-streaming signals of phosphorylated Smad2/3, was markedly induced by LRRC25 deficiency. LRRC25-knockout mice showed a significantly enhanced inflammation in response to AB surgery by promoting the activation of NF-κB signaling pathway. In mouse cardiomyocytes, LRRC25 deficiency markedly elevated TGF-β1 and NF-κB activation stimulated by Ang II. Treatment with a combination of TGF-β1 or NF-κB inhibitor abolished the effects of LRRC25-knockout on the promotion of cardiac hypertrophy in vitro. Together, our study identified LRRC25 as a critical molecular switch whose down-regulation resulted in cardiac hypertrophy in a TGF-β1- and NF-κB-dependent manner.

Relationship between the NF-κB1-94ins/del ATTG locus polymorphism and risk of hypertension in the Chinese Han population

Objective: The onset of essential hypertension is the result of a combination of genetic factors and the environment. The nuclear factor (NF)-κB1-94ins/del ATTG locus polymorphism is associated with the occurrence of various diseases. The purpose of this study was to find out the relationship between the NF-κB1-94ins/del ATTG locus polymorphism and the risk of hypertension in the Chinese Han population. Methods: A total of 585 Chinese Han patients with essential hypertension and 585 Chinese Han healthy volunteers were recruited. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to analyze the genotype of the NF-κB1-94ins/del ATTG locus in all the subjects. Results: For the NF-κB1-94ins/del ATTG locus, the dominant (adjusted odds ratio [OR] = 1.31, 95% confidence interval [CI] = 1.13-1.54, P < 0.001), recessive (adjusted OR = 1.17, 95% CI = 1.02-1.32, P = 0.03) and additive (adjusted OR = 1.19, 95% CI = 1.03-1.36, P = 0.01) models showed significant increase in the risk of hypertension. The NF-κB1-94ins/del ATTG locus II genotype was an independent risk factor for hypertension (OR = 1.15, 95% CI = 0.78-1.69, P = 0.02). The interaction between the NF-κB1-94ins/del ATTG locus polymorphism and BMI, alcohol consumption, and diabetes significantly increased the risk of hypertension (OR = 1.71, 95% CI = 1.26-1.86, P < 0.01). Conclusion: The NF-κB1-94ins/del ATTG polymorphism is an independent risk factor for essential hypertension. The NF-κB1-94ins/del ATTG locus, obesity, drinking, and diabetes also interact to yield a higher risk of hypertension.

Arachidonic acid in health and disease with focus on hypertension and diabetes mellitus: A review

Arachidonic acid (AA 20:4n-6) is an essential component of cell membranes and modulates cell membrane fluidity. AA is metabolized by cyclo-oxygenase (COX), lipoxygenase (LOX) and cytochrome P450 enzymes to form several metabolites that have important biological actions. Of all the actions, role of AA in the regulation of blood pressure and its ability to prevent both type 1 and type 2 diabetes mellitus seems to be interesting. Studies showed that AA and its metabolites especially, lipoxin A4 (LXA4) and epoxyeicosatrienoic acids (EETs), potent anti-inflammatory metabolites, have a crucial role in the pathobiology of hypertension and diabetes mellitus. AA, LXA4 and EETs regulate smooth muscle function and proliferation, voltage gated ion channels, cell membrane fluidity, membrane receptors, G-coupled receptors, PPARs, free radical generation, nitric oxide formation, inflammation, and immune responses that, in turn, participate in the regulation blood pressure and pathogenesis of diabetes mellitus. In this review, role of AA and its metabolites LXA4 and EETs in the pathobiology of hypertension, pre-eclampsia and diabetes mellitus are discussed. Based on several lines of evidences, it is proposed that a combination of aspirin and AA could be of benefit in the prevention and management of hypertension, pre-eclampsia and diabetes mellitus.

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.

Neuroinflammatory mechanisms of hypertension: potential therapeutic implications

PURPOSE OF REVIEW

Inflammation of forebrain and hindbrain nuclei has recently been highlighted as an emerging factor in the pathogenesis of neurogenic hypertension. The aim of this review is to summarize the state of the art in this field and to discuss recently discovered pathophysiological mechanisms, opening new perspectives for therapeutic application.

RECENT FINDINGS

Microglia Toll-like receptor 4 causally links angiotensin II (AngII)-mediated microglia cell activation and oxidative stress within the hypothalamic paraventricular nucleus (PVN). Toll-like receptor 4 can also be activated by lipopolysaccharides. PVN infusion of nuclear factor κB inhibitor lowers the blood pressure and ameliorates cardiac hypertrophy. Ang-(1-7) exerts direct effects on microglia, causing a reduction in both baseline and prorenin-induced release of proinflammatory cytokines. A compromised blood-brain barrier (BBB) constitutes a complementary mechanism that exacerbates AngII-driven neurohumoral activation, contributing to the development of hypertension.

SUMMARY

PVN and BBB seem to be pivotal targets for therapeutic intervention in hypertension. Recent advances in imaging techniques enable visualization of the inflammatory state in microglia and BBB integrity in humans. AngII type I receptor blockers and AngII-converting enzyme inhibitors are the most likely candidates for controlled randomized trials in humans aimed at amelioration of brain inflammation in the forthcoming years.

γδ T cells provide the early source of IFN-γ to aggravate lesions in spinal cord injury

Immune responses and neuroinflammation are critically involved in spinal cord injury (SCI). γδ T cells, a small subset of T cells, regulate the inflammation process in many diseases, yet their function in SCI is still poorly understood. In this paper, we demonstrate that mice deficient in γδ T cells (TCRδ^-/- ) showed improved functional recovery after SCI. γδ T cells are detected at the lesion sites within 24 hours after injury and are predominantly of the Vγ4 subtype and express the inflammatory cytokine IFN-γ. Inactivating IFN-γ signaling in macrophages results in a significantly reduced production of proinflammatory cytokines in the cerebrospinal fluid (CSF) of mice with SCIs and improves functional recovery. Furthermore, treatment of SCI with anti-Vγ4 antibodies has a beneficial effect, similar to that obtained with anti-TNF-α. In SCI patients, γδ T cells are detected in the CSF, and most of them are IFN-γ positive. In conclusion, manipulation of γδ T cell functions may be a potential approach for future SCI treatment.

Role of NLRP3 inflammasome in the pathogenesis of cardiovascular diseases

NLRP3 inflammasome is a key multiprotein signaling platform that tightly controls inflammatory responses and coordinates antimicrobial host defenses by activating caspase-1 for the subsequent maturation of pro-inflammatory cytokines, IL-1β and IL-18, and induces pyroptosis. The assembly and activation of NLRP3 inflammasome are linked to the pathogenesis of several cardiovascular disease risk factors, such as hypertension and diabetes, and their major consequences-myocardial remodeling. The study of the NLRP3 inflammasome in these cardiovascular disease states may uncover important triggers and endogenous modulators of the disease, and lead to new treatment strategies. This review outlines current insights into NLRP3 inflammasome research associated with cardiovascular diseases and discusses the questions that remain in this field.

The emerging role of NADPH oxidase NOX5 in vascular disease

Oxidative stress is a consequence of up-regulation of pro-oxidant enzyme-induced reactive oxygen species (ROS) production and concomitant depletion of antioxidants. Elevated levels of ROS act as an intermediate and are the common denominator for various diseases including diabetes-associated macro-/micro-vascular complications and hypertension. A range of enzymes are capable of generating ROS, but the pro-oxidant enzyme family, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), are the only enzymes known to be solely dedicated to ROS generation in the vascular tissues, kidney, aortas and eyes. While there is convincing evidence for a role of NOX1 in vascular and eye disease and for NOX4 in renal injury, the role of NOX5 in disease is less clear. Although NOX5 is highly up-regulated in humans in disease, it is absent in rodents. Thus, so far it has not been possible to study NOX5 in traditional mouse or rat models of disease. In the present review, we summarize and critically analyse the emerging evidence for a pathophysiological role of NOX5 in disease including the expression, regulation and molecular and cellular mechanisms which have been demonstrated to be involved in NOX5 activation.

Stachydrine ameliorates isoproterenol-induced cardiac hypertrophy and fibrosis by suppressing inflammation and oxidative stress through inhibiting NF-κB and JAK/STAT signaling pathways in rats

Cardiac hypertrophy (CH), as one of the major causes of morbidity and mortality in the world, has become an independent and predictive risk factor for adverse cardiovascular events. However, progress in treatment remains sluggish in recent years. Therefore, compounds derived from non-toxic nature plants are urgently needed. Stachydrine (STA), which is isolated from Leonurus, has various activities, including resistance to cardiovascular disease, but little is known about its effect on CH or the mechanisms. We herein investigated the effect of STA on isoproterenol-induced CH and the underlying mechanisms. Treatment with STA significantly increased the ratios of heart weight/body weight, left ventricle weight/body weight and the cross-sectional areas of cardiomyocytes. In addition, STA significantly decreased the mRNA levels of atrial natriuretic peptide, B-type natriuretic peptide and β-myosin heavy chain. Furthermore, isoproterenol-induced fibrosis in rats receiving STA was significant attenuated, as evidenced by decreased ratio of fibrotic area/total area and decreased mRNA levels of collagens I and III. Given down-regulation of interleukin-6, tumor necrosis factor-α, interferon-γ (IFN-γ) and IFN-1β, treatment with STA significantly reversed the expressions of pro-inflammatory induced by isoproterenol. Moreover, STA attenuated the oxidative stress level in serum of isoproterenol-induced CH rats, as shown by increased activity of superoxide dismutase and decreased malondialdehyde level. STA inhibited the expressions of phosphorylated IκBα, NF-κB p65, JAK2 and STAT3 in vivo. Thus, both NF-κB and JAK/STAT signalings played essential roles in mediating the anti-CH effect of STA. Collectively, STA has a potent protective effect on isoproterenol-induced CH, with therapeutic implication for CH.

PVN Blockade of p44/42 MAPK Pathway Attenuates Salt-induced Hypertension through Modulating Neurotransmitters and Attenuating Oxidative Stress

The imbalance of neurotransmitters and excessive oxidative stress responses contribute to the pathogenesis of hypertension. In this study, we determined whether blockade of p44/42 MAPK pathway in the hypothalamic paraventricular nucleus (PVN) ameliorates the development of hypertension through modulating neurotransmitters and attenuating oxidative stress. Dahl salt-sensitive (S) rats received a high-salt diet (HS, 8% NaCl) or a normal-salt diet (NS, 0.3% NaCl) for 6 weeks and were treated with bilateral PVN infusion of PD-98059 (0.025 μg/h), a p44/42 MAPK inhibitor, or vehicle via osmotic minipump. HS resulted in higher mean arterial pressure (MAP) and Fra-like (Fra-LI) activity, and plasma and PVN levels of norepinephrine (NE), tyrosine hydroxylase (TH), NOX2 and NOX4, lower PVN levels of gamma-aminobutyric acid (GABA), copper/zinc superoxide dismutase (Cu/Zn-SOD) and the 67-kDa isoform of glutamate decarboxylase (GAD67), as compared with NS group. PD-98059 infusion reduced NE, TH, NOX2 and NOX4 in the PVN, and induced Cu/Zn-SOD and GAD67 in the PVN. It suggests that PVN blockade of p44/42 MAPK attenuates hypertension through modulating neurotransmitters and attenuating oxidative stress.

Targeting Interleukin-1 beta to Suppress Sympathoexcitation in Hypothalamic Paraventricular Nucleus in Dahl Salt-Sensitive Hypertensive Rats

Findings from our laboratory indicate that expressions of some proinflammatory cytokines such as tumor necrosis factor, interleukin-6 and oxidative stress responses are increased in the hypothalamic paraventricular nucleus (PVN) and contribute to the progression of salt-sensitive hypertension. In this study, we determined whether interleukin-1 beta (IL-1β) activation within the PVN contributes to sympathoexcitation during development of salt-dependent hypertension. Eight-week-old male Dahl salt-sensitive (S) rats received a high-salt diet (HS, 8 % NaCl) or a normal-salt diet (NS, 0.3 % NaCl) for 6 weeks, and all rats were treated with bilateral PVN injection of gevokizumab (IL-1β inhibitor, 1 μL of 10 μg) or vehicle once a week. The mean arterial pressure (MAP), heart rate (HR) and plasma norepinephrine (NE) were significantly increased in high-salt-fed rats. In addition, rats with high-salt diet had higher levels of NOX-2, NOX-4 [subunits of NAD (P) H oxidase], IL-1β, NLRP3 (NOD-like receptor family pyrin domain containing 3), Fra-LI (an indicator of chronic neuronal activation) and lower levels of IL-10 in the PVN than normal-diet rats. Bilateral PVN injection of gevokizumab decreased MAP, HR and NE, attenuated the levels of oxidative stress and restored the balance of cytokines. These findings suggest that IL-1β activation in the PVN plays a role in salt-sensitive hypertension.

NF-κB Blockade in Hypothalamic Paraventricular Nucleus Inhibits High-Salt-Induced Hypertension Through NLRP3 and Caspase-1

High-salt-induced inflammation and oxidative stress in the hypothalamic paraventricular nucleus (PVN) contribute to the pathogenesis of salt-sensitive hypertension. In this study, we hypothesized that chronic inhibition of nuclear factor-κB (NF-κB) activity in the PVN delays the progression of hypertension by upregulating anti-inflammatory cytokines, reducing NLRP3 (NOD-like receptor family pyrin domain containing 3) and IL-1β and attenuating p-IKKβ, NF-κB p65 activity and NAD(P)H oxidase in the PVN of salt-sensitive hypertensive rats. Dahl salt-sensitive rats received a high-salt diet (HS, 8 % NaCl) or a normal-salt diet (NS, 0.3 % NaCl) for 6 weeks and were treated with bilateral PVN infusion with either vehicle or pyrrolidine dithiocarbamate (PDTC, 5 μg/h), a NF-κB inhibitor via osmotic minipump. The mean arterial pressure and plasma levels of norepinephrine (NE) and epinephrine (EPI) were significantly increased in high-salt-fed rats. In addition, rats with high-salt diet had higher levels of p-IKKβ, NF-κB p65 activity, Fra-like (Fra-LI) activity (an indicator of chronic neuronal activation), NOX-4 (subunits of NAD(P)H oxidase), NLRP3 and IL-1β, and lower levels of IL-10 in the PVN than normal diet rats. Bilateral PVN infusions of PDTC attenuated these high-salt-induced changes. These findings suggest that high-salt-induced NF-κB activation in the PVN caused hypertension via sympathoexcitation, which are associated with the increases of NLRP3, IL-1β and oxidative stress in the PVN; PVN inhibition of NF-κB activity attenuates NLRP3, IL-1β and oxidative stress in the PVN and thereby attenuates hypertension.

Exercise training attenuates renovascular hypertension partly via RAS- ROS- glutamate pathway in the hypothalamic paraventricular nucleus

Exercise training (ExT) has been reported to benefit hypertension; however, the exact mechanisms involved are unclear. We hypothesized that ExT attenuates hypertension, in part, through the renin-angiotensin system (RAS), reactive oxygen species (ROS), and glutamate in the paraventricular nucleus (PVN). Two-kidney, one-clip (2K1C) renovascular hypertensive rats were assigned to sedentary (Sed) or treadmill running groups for eight weeks. Dizocilpine (MK801), a glutamate receptor blocker, or losartan (Los), an angiotensin II type1 receptor (AT1-R) blocker, were microinjected into the PVN at the end of the experiment. We found that 2K1C rats had higher mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). These rats also had excessive oxidative stress and overactivated RAS in PVN. Eight weeks of ExT significantly decreased MAP and RSNA in 2K1C hypertensive rats. ExT inhibited angiotensin-converting enzyme (ACE), AT1-R, and glutamate in the PVN, and angiotensin II (ANG II) in the plasma. Moreover, ExT attenuated ROS by augmenting copper/zinc superoxide dismutase (Cu/Zn-SOD) and decreasing p^47phox and gp^91phox in the PVN. MK801or Los significantly decreased blood pressure in rats. Together, these findings suggest that the beneficial effects of ExT on renovascular hypertension may be, in part, through the RAS-ROS-glutamate pathway in the PVN.

Age-dependent alterations to paraventricular nucleus insulin-like growth factor 1 receptor as a possible link between sympathoexcitation and inflammation

Modifications to neural circuits of the paraventricular hypothalamic nucleus (PVN) have been implicated in sympathoexcitation and systemic cardiovascular dysfunction. However, to date, the role of insulin-like growth factor 1 receptor (IGF-1R) expression on PVN pathophysiology is unknown. Using confocal immunofluorescence quantification and electrophysiological recordings from acute PVN slices, we investigated the mechanism through which age-dependent IGF-1R depletion contributes to the progression of inflammation and sympathoexcitation in the PVN of spontaneously hypertensive rats (SHR). Four and twenty weeks old SHR and Wistar Kyoto (WKY) rats were used for this study. Our data showed that angiotensin I/II and pro-inflammatory high mobility box group protein 1 (HMGB1) exhibited increased expression in the PVN of SHR versus WKY at 4 weeks (p < 0.01), and were even more highly expressed with age in SHR (p < 0.001). This correlated with a significant decrease in IGF-1R expression, with age, in the PVN of SHR when compared with WKY (p < 0.001) and were accompanied by related changes in astrocytes and microglia. In subsequent analyses, we found an age-dependent change in the expression of proteins associated with IGF-1R signaling pathways involved in inflammatory responses and synaptic function in the PVN. MAPK/ErK was more highly expressed in the PVN of SHR by the fourth week (p < 0.001; vs. WKY), while expression of neuronal nitric oxide synthase (p < 0.001) and calcium-calmodulin-dependent kinase II alpha (CamKIIα; p < 0.001) were significantly decreased by the 4th and 20th week, respectively. Age-dependent changes in MAPK/ErK expression in the PVN correlated with an increase in the expression of vesicular glutamate transporter (p < 0.001 vs. WKY), while decreased levels of CamKIIα was associated with a decreased expression of tyrosine hydroxylase (p < 0.001) by the 20th week. In addition, reduced labeling for ϒ-aminobutyric acid in the PVN of SHR (p < 0.001) correlated with a decrease in neuronal nitric oxide synthase labeling (p < 0.001) when compared with the WKY by the 20th week. Electrophysiological recordings from neurons in acute slice preparations of the PVN of 4 weeks old SHR revealed spontaneous post-synaptic currents of higher frequency when compared with neurons from WKY PNV slices of the same age (p < 0.001; n = 14 cells). This also correlated with an increase in PSD-95 in the PVN of SHR when compared with the WKY (p < 0.001). Overall, we found an age-dependent reduction of IGF-1R, and related altered expression of associated downstream signaling molecules that may represent a link between the concurrent progression of synaptic dysfunction and inflammation in the PVN of SHR.

Pomegranate extract decreases oxidative stress and alleviates mitochondrial impairment by activating AMPK-Nrf2 in hypothalamic paraventricular nucleus of spontaneously hypertensive rats

High blood pressure, or “hypertension,” is associated with high levels of oxidative stress in the paraventricular nucleus of the hypothalamus. While pomegranate extract is a known antioxidant that is thought to have antihypertensive effects, the mechanism whereby pomegranate extract lowers blood pressure and the tissue that mediates its antihypertensive effects are currently unknown. We have used a spontaneously hypertensive rat model to investigate the antihypertensive properties of pomegranate extract. We found that chronic treatment of hypertensive rats with pomegranate extract significantly reduced blood pressure and cardiac hypertrophy. Furthermore, pomegranate extract reduced oxidative stress, increased the antioxidant defense system, and decreased inflammation in the paraventricular nucleus of hypertensive rats. We determined that pomegranate extract reduced mitochondrial superoxide anion levels and increased mitochondrial function in the paraventricular nucleus of hypertensive rats by promoting mitochondrial biogenesis and improving mitochondrial dynamics and clearance. We went on to identify the AMPK-nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) pathway as a mechanism whereby pomegranate extract reduces oxidative stress in the paraventricular nucleus to relieve hypertension. Our findings demonstrate that pomegranate extract alleviates hypertension by reducing oxidative stress and improving mitochondrial function in the paraventricular nucleus, and reveal multiple novel targets for therapeutic treatment of hypertension.

Effect of 4-week inhalation exposure to 1-bromopropane on blood pressure in rats

The pathophysiology of hypertension is complex and multifactorial, and includes exposure to various chemical substances. Several recent studies have documented the reproductive and neurological toxicities of 1-bromopropane (1-BP). Given that 1-BP increased reactive oxygen species in the brain of rats, we hypothesized that 1-BP also has cardiovascular toxicity through increased oxidative stress. To test this hypothesis, male F344 and Wistar Nagoya rats (n = 7-8 per group per test) were exposed to 0 or 1000 ppm of 1-BP via inhalation for 4 weeks (8 h per day, 7 days per week). The exposure to 1-BP increased systolic blood pressure. This effect was associated with a significant decrease in the reduced/oxidized glutathione ratio. A significant increase in nitrotyrosine levels, activation of the NADPH oxidase pathway, which was evidenced by upregulation of gp91phox, a NADPH oxidase subunit, and significant decreases in the expressions of antioxidant molecules such as Cu/Zn- and Mn-superoxide dismutase catalase, and nuclear factor erythroid 2-related factor 2, were observed in the aortas of Wistar Nagoya rats exposed to 1-BP. Our results indicate that subacute (4-week) inhalation exposure to 1-BP increases blood pressure and suggest that this cardiovascular toxic effect is due, at least in part, to increased oxidative stress mediated through activation of the NADPH oxidase pathway. Further study is needed to assess whether NADPH oxidase activation causes the increase in blood pressure in the rats exposed to 1-BP. Copyright © 2016 John Wiley & Sons, Ltd.

Oral CoQ10 attenuates high salt-induced hypertension by restoring neurotransmitters and cytokines in the hypothalamic paraventricular nucleus

High salt intake leads to an increase in some proinflammatory cytokines and neurotransmitters involved in the pathogenesis of hypertension. The purpose of this work was to know if oral administration of anti-oxidant and free-radical scavenger CoQ10 may attenuate high salt-induced hypertension via regulating neurotransmitters and cytokines in the hypothalamic paraventricular nucleus (PVN). Adult male Sprague-Dawley (SD) rats were fed with a normal salt diet (NS, 0.3% NaCl) or a high salt diet (HS, 8% NaCl) for 15 weeks to induce hypertension. These rats received CoQ10 (10 mg/kg/day) dissolved in olive oil was given by gavage (10 mg/kg/day) for 15 weeks. HS resulted in higher mean arterial pressure (MAP) and the sympathetic nerve activity (RSNA). These HS rats had higher PVN levels of norepinephrine (NE), tyrosine hydroxylase (TH), interleukin (IL)-1β, NOX2 and NOX4, lower PVN levels of gamma-aminobutyric acid (GABA), IL-10, copper/zinc superoxide dismutase (Cu/Zn-SOD) and the 67-kDa isoform of glutamate decarboxylase (GAD67), as compared with NS group. CoQ10 supplementation reduced NE, TH, IL-1β, NOX2 and NOX4 in the PVN, and induced IL-10, Cu/Zn-SOD and GAD67 in the PVN. These findings suggest that CoQ10 supplementation restores neurotransmitters and cytokines in the PVN, thereby attenuating high salt-induced hypertension.