Activated pathogenic Th17 lymphocytes induce hypertension following high-fructose intake in Dahl salt-sensitive but not Dahl salt-resistant rats

Increased lamina propria B cells play roles in fructose-induced hypertension of Dahl salt-sensitive rats

AIMS

Although the immune system participates in the development of hypertension, the proportional contributions of distinct immune cells remain poorly understood. With the development of transcriptomics, we can profile the transcriptomes of individual immune cells and assess the relative contribution of each immune cell to the development of hypertension. So, we tested the hypothesis that increased lamina propria B cells play roles in fructose-induced hypertension of Dahl salt-sensitive (SS) rats.

MATERIALS AND METHODS

Eight-week-old Dahl SS and Dahl salt-resistant (SR) male rats were divided into four groups; each group received either tap water (TW) or a 20 % fructose solution (HFS) for 4 weeks. Systolic blood pressure was measured using the tail-cuff method. Single-cell RNA sequencing (scRNA-seq) analysis was performed on lamina propria (LP) cells and peripheral blood mononuclear cells (PBMCs) obtained from the SS and SR rats subjected to either TW or HFS.

KEY FINDINGS

Results revealed that high-fructose intake induced hypertension in the SS rats but not in the SR rats. It also increased B cells in LPs but not in PBMCs of the SS rats; their subsets showed increased follicular and naïve B cells. Increased lamina propria B cells play roles in fructose-induced hypertension of SS rats.

SIGNIFICANCE

This finding suggest that targeting B cells could be a potential strategy to mitigate high blood pressure in fructose-induced hypertension.

Unraveling the gut microbiota's role in salt-sensitive hypertension: current evidences and future directions

The gut microbiota plays a pivotal role in both maintaining human health and in the pathogenesis of diseases. Recent studies have brought to light the significant correlation between gut microbiota and hypertension, particularly focusing on its role in the development and advancement of SSH, a subtype characterized by elevated blood pressure in response to high salt consumption. The complexity of SSH's etiology is notable, with dysbiosis of the gut microbiome identified as a crucial contributing factor. The gut microbiota participates in the occurrence and development of SSH by affecting the host's immune system, metabolic function, and neuromodulation. Investigations have demonstrated that the gut microbes regulate the development of SSH by regulating the TH17 axis and the activity of immune cells. Moreover, microbial metabolites, such as short-chain fatty acids, are implicated in blood pressure regulation and affect the development of SSH. There is evidence to show that the composition of the gut microbiome can be altered through prebiotic interventions so as to prevent and treat SSH. This review aims to concisely sum up the role of gut microbiota in SSH and to discuss pertinent therapeutic strategies and clinical implications, thereby providing a valuable reference for further research and clinical practice in this area.

Single cell transcriptome analyses reveal the roles of B cells in fructose-induced hypertension

Rationale

While the immune system plays a crucial role in the development of hypertension, the specific contributions of distinct immune cell populations remain incompletely understood. The emergence of single-cell RNA-sequencing (scRNA-seq) technology enables us to analyze the transcriptomes of individual immune cells and to assess the significance of each immune cell type in hypertension development.

Objective

We aimed to investigate the hypothesis that B cells play a crucial role in the development of fructose-induced hypertension.

Methods and Results

Eight-week-old Dahl salt-sensitive (SS) male rats were divided into two groups and given either tap water (TW) or a 20% fructose solution (HFS) for 4 weeks. Systolic blood pressure was measured using the tail-cuff method. ScRNA-seq analysis was performed on lamina propria cells (LPs) and peripheral blood mononuclear cells (PBMCs) obtained from SS rats subjected to either TW or HFS. The HFS treatment induced hypertension in the SS rats. The analysis revealed 27 clusters in LPs and 28 clusters in PBMCs, allowing for the identification and characterization of various immune cell types within each cluster. Specifically, B cells and follicular helper T (Tfh) cells were prominent in LPs, while B cells and M1 macrophages dominated PBMCs in the HFS group. Moreover, the HFS treatment triggered an increase in the number of B cells in both LPs and PBMCs, accompanied by activation of the interferon pathway.

Conclusions

The significant involvement of B cells in intestinal and PBMC responses indicates their pivotal contribution to the development of hypertension. This finding suggests that targeting B cells could be a potential strategy to mitigate high blood pressure in fructose-induced hypertension. Moreover, the simultaneous increase in follicular B cells and Tfh cells in LPs, along with the upregulation of interferon pathway genes in B cells, underscores a potential autoimmune factor contributing to the pathogenesis of fructose-induced hypertension in the intestine.

Hypertonic Salt Solution Enhances Inflammatory Responses in Cultured Splenic T-Cells from Dahl Salt-Sensitive Rats but Not Dahl Salt-Resistant Rats

This study aimed to delineate the effect of sodium chloride on the induction of inflammatory responses and the development of hypertension in Dahl salt-sensitive (SS) and salt-resistant (SR) rats. Splenocytes were isolated from the spleens of SS and SR rats, and cultured on anti-CD3-coated plates for 5 days. The cultured splenic T-cells were challenged with a hypertonic salt solution (0, 20, or 40 mM) in the absence or presence of IL-6 (0, 20, or 60 ng/mL), TGF-β (0, 5, or 15 ng/mL), or IL-23 (0, 10, or 30 ng/mL), and analyzed via ELISA, flow cytometry, and immunofluorescence. The hypertonic salt solution potentiated IL-17A production, as well as the differentiation of Th17 cells via IL-6/TGF-β/IL-23, exclusively in SS rats. However, it did not affect IL-10 production or the differentiation of Treg cells in any of the groups. Furthermore, it potentiated the signal of RORγt in IL-6-treated splenic T-cells from SS rats. To summarize, cultured splenic T-cells exhibited enhanced inflammatory responses on exposure to a hypertonic salt solution in SS rats only, which indicated that sodium chloride and inflammatory cytokines synergistically drove the induction of pathogenic Th17 cells and the development of hypertension in this group only.

T helper cell polarity determines salt sensitivity and hypertension development

High-salt intake is known to induce pathogenic T helper (Th) 17 cells and hypertension, but contrary to what is known, causes hypertension only in salt-sensitive (SS) individuals. Thus, we hypothesized that Th cell polarity determines salt sensitivity and hypertension development. Cultured splenic T cells from Dahl SS and salt-resistant (SR) rats subjected to hypertonic salt solutions were evaluated via ELISA, flow cytometry, immunocytochemistry and RT-qPCR. Seven-week-old SS and SR rats were fed a chow (CD) or high-salt diet (HSD) for 4 weeks, with weekly measurements of systolic blood pressure. The relaxation response of the aorta rings to the cumulative addition of acetylcholine was measured ex vivo. In these experimental animals, the Th cell polarity (Th17 and T regulatory [Treg]), the expression of Th17- or Treg-related genes, and the enrichment of the transcription factors RORγt and FOXP3 on the target gene promoter regions were determined via flow cytometry, RT-qPCR, and chromatin immunoprecipitation. Hypertonic salt solution induced Th17 and Treg cell differentiation in cultured splenic T cells isolated from SS and SR rats, respectively. HSD induced hypertension, endothelial dysfunction and proinflammatory Th17 cell differentiation only in SS rats. The enrichment of RORγt on the promoter regions of Il17a and Il23r increased their expression only in SS rats. Regardless of HSD, SR rats remained normotensive with Treg polarity, causing high Treg-related gene expressions (Il10, Cd25 and Foxp3). This study demonstrated that Th cell polarity determines salt sensitivity and drives hypertension development. SR rats were protected from HSD-associated hypertension via anti-inflammatory Treg polarity.

The role of dietary salt in metabolism and energy balance: Insights beyond cardiovascular disease

Dietary salt (NaCl) is essential to an organism's survival. However, today's diets are dominated by excessive salt intake, which significantly impacts individual and population health. High salt intake is closely linked to cardiovascular disease (CVD), especially hypertension, through a number of well-studied mechanisms. Emerging evidence indicates that salt overconsumption may also be associated with metabolic disorders. In this review, we first summarize recent updates on the mechanisms of salt-induced CVD, the effects of salt reduction and the use of salt substitution as a therapy. Next, we focus on how high salt intake can impact metabolism and energy balance, describing the mechanisms through which this occurs, including leptin resistance, the overproduction of fructose and ghrelin, insulin resistance and altered hormonal factors. A further influence on metabolism worth noting is the reported role of salt in inducing thermogenesis and increasing body temperature, leading to an increase in energy expenditure. While this result could be viewed as a positive metabolic effect because it promotes a negative energy balance to combat obesity, caution must be taken with this frame of thinking given the deleterious consequences of chronic high salt intake on cardiovascular health. Nevertheless, this review highlights the importance of salt as a noncaloric nutrient in regulating whole-body energy homeostasis. Through this review, we hope to provide a scientific framework for future studies to systematically address the metabolic impacts of dietary salt and salt replacement treatments. In addition, we hope to form a foundation for future clinical trials to explore how these salt-induced metabolic changes impact obesity development and progression, and to elucidate the regulatory mechanisms that drive these changes, with the aim of developing novel therapeutics for obesity and CVD.

The process of hypertension induced by high-salt diet: Association with interactions between intestinal mucosal microbiota, and chronic low-grade inflammation, end-organ damage

Inflammation and immunity play a major role in the development of hypertension, and a potential correlation between host mucosal immunity and inflammatory response regulation. We explored the changes of intestinal mucosal microbiota in hypertensive rats induced by high-salt diet and the potential link between the intestinal mucosal microbiota and inflammation in rats. Therefore, we used PacBio (Pacific Bioscience) SMRT sequencing technology to determine the structure of intestinal mucosal microbiota, used enzyme-linked immunosorbent assay (ELISA) to determined the proinflammatory cytokines and hormones associated with hypertension in serum, and used histopathology methods to observe the kidney and vascular structure. We performed a potential association analysis between intestinal mucosal characteristic bacteria and significantly different blood cytokines in hypertensive rats induced by high-salt. The results showed that the kidney and vascular structures of hypertensive rats induced by high salt were damaged, the serum concentration of necrosis factor-α (TNF-α), angiotensin II (AngII), interleukin-6 (IL-6), and interleukin-8 (IL-8) were significantly increased (p < 0.05), and the coefficient of immune organ spleen was significantly changed (p < 0.05), but there was no significant change in serum lipids (p > 0.05). From the perspective of gut microbiota, high-salt diet leads to significant changes in intestinal mucosal microbiota. Bifidobacterium animalis subsp. and Brachybacterium paraconglomeratum were the dominant differential bacteria in intestinal mucosal, with the AUC (area under curve) value of Bifidobacterium animalis subsp. and Brachybacterium paraconglomeratum were 1 and 0.875 according to ROC (receiver operating characteristic) analysis. Correlation analysis showed that Bifidobacterium animalis subsp. was correlated with IL-6, IL-8, TNF-α, and Ang II. Based on our results, we can speculated that high salt diet mediated chronic low-grade inflammation through inhibited the growth of Bifidobacterium animalis subsp. in intestinal mucosa and caused end-organ damage, which leads to hypertension.

Angiotensin II-induced a steeper blood pressure elevation in IL-23 receptor-deficient mice: Role of interferon-γ-producing T cells

A subset of interleukin (IL)-17A-producing γδ T cells called γδT17 cells may contribute to progression of hypertension. γδT17 cell development is in part dependent upon IL-23 receptor (IL-23R) stimulation. We hypothesized that angiotensin (Ang) II-induced blood pressure (BP) elevation and vascular injury would be blunted in Il23r knock-in (Il23r^gfp/gfp) mice deficient in functional IL-23R. To test this hypothesis, we infused wild-type (WT) and Il23r^gfp/gfp mice with Ang II (490 ng/kg/min, SC) for 7 or 14 days. We recorded BP by telemetry, assessed vascular function and remodeling using pressurized myography, and profiled T cell populations and cytokine production by flow cytometry. An additional set of Il23r^gfp/gfp mice was infused with Ang II for 7 days and injected with interferon (IFN)-γ-neutralizing or control antibodies. Il23r^gfp/gfp mice had smaller and stiffer mesenteric arteries and were not protected against Ang II-induced BP elevation. BP was higher in Il23r^gfp/gfp mice than WT mice from day 3 until day 9 of Ang II infusion. Il23r^gfp/gfp mice had less γδT17 cells and more IFN-γ-producing γδ, CD4⁺, and CD8⁺ T cells than WT mice. Seven days of Ang II infusion led to increased IFN-γ-producing γδ, CD4⁺, and CD8⁺ T cells in Il23r^gfp/gfp mice, whereas only IFN-γ-producing γδ T cells were increased in WT mice. Blocking IFN-γ with a neutralizing antibody reduced the pressor response to 7 days of Ang II infusion in Il23r^gfp/gfp mice. Functional IL-23R deficiency was associated with increased IFN-γ-producing T cells and exaggerated initial development of Ang II-induced hypertension, which was in part mediated by IFN-γ.

Physiopathological mechanisms involved in the development of hypertension associated with gut dysbiosis and the effect of nutritional/pharmacological interventions

The gut microbiota dysbiosis represents a triggering factor for cardiovascular diseases, including hypertension. In addition to the harmful impact caused by hypertension on different target organs, gut dysbiosis is capable of causing direct damage to critical organs such as the brain, heart, blood vessels, and kidneys. In this sense, it should be noted that pharmacological and nutritional interventions may influence gut microbiota composition, either inducing or preventing the development of hypertension. Some of the most important nutritional interventions at this level are represented by pro-, pre-, post- and/or syn-biotics, as well as polysaccharides, polyunsaturated fatty acids ω-3, polyphenols and fiber contained in different foods. Meanwhile, certain natural and synthetic active pharmaceutical ingredients, including antibiotics, antihypertensive and immunosuppressive drugs, vegetable extracts and vitamins, may also have a key role in the modulation of both gut microbiota and cardiovascular health. Additionally, gut microbiota may influence drugs and food-derived bioactive compounds metabolism, positively or negatively affecting their biological behavior facing established hypertension. The understanding of the complex interactions between gut microbiome and drug/food response results of great importance to developing improved pharmacological therapies for hypertension prevention and treatment. The purpose of this review is to critically outline the most relevant and recent findings on cardiovascular, renal and brain physiopathological mechanisms involved in the development of hypertension associated with changes in gut microbiota, besides the nutritional and pharmacological interventions potentially valuable for the prevention and treatment of this prevalent pathology. Finally, harmful food/drug interventions on gut microbiota are also described.

Dahl Salt-Resistant Rat Is Protected against Hypertension during Diet-Induced Obesity

A high-fat diet (HFD) frequently causes obesity-induced hypertension. Because Dahl salt-resistant rats are protected against hypertension after high-salt or high-fructose intake, it is of interest whether this model also protects against hypertension after diet-induced obesity. We tested the hypothesis that Dahl salt-resistant rat protects against hypertension during diet-induced obesity. Dahl salt-sensitive (SS) and Dahl salt-resistant (SR) rats were fed a HFD (60% fat) or a chow diet (CD; 8% fat) for 12 weeks. We measured blood pressure using the tail-cuff method. The paraffin sections of thoracic perivascular adipose tissue (tPVAT) were stained with hematoxylin/eosin and trichrome. The expression of genes in the tPVAT and kidneys were measured by reverse transcription-quantitative polymerase chain reaction. The HFD induced hypertension in SS (p < 0.01) but not SR rats, although it increased body weight gain (p < 0.05) and tPVAT weight (p < 0.01) in both rats. The HFD did not affect the expression of genes related to any of the adipocyte markers in both rats, although SR rats had reduced beige adipocyte marker Tmem26 levels (p < 0.01) and increased anti-inflammatory cytokine adiponectin (p < 0.05) as compared with SS rat. The HFD did not affect the mRNA expression of contractile factors in the tPVAT of SS and SR rats. SR rats are protected against hypertension during diet-induced obesity. This result implies that the genetic trait determining salt sensitivity may also determine fructose and fat sensitivity and that it is associated with the prevention of hypertension.

Role of Oxidative Stress in Vascular Low-Grade Inflammation Initiation Due to Acute Salt Loading in Young Healthy Individuals

This study aimed to investigate the effect of 7-day high-salt (HS) and the specific role of oxidative stress on vascular low-grade inflammation initiation in young salt-resistant healthy individuals. 30 young healthy individuals adhered to a 7-day low-salt (LS) diet (3.5 g salt/day), followed by a 7-day high-salt (HS) diet (~14.7 g salt/day) protocol. Pro- and anti-inflammatory cytokines, frequencies of peripheral blood Th17 and Treg cells, Th17/Treg ratio, enzymes SGK1, and p38/MAP kinase, as well as biomarkers of endothelial activation and oxidative stress, were measured before and after the 7-day HS diet protocol. Short-term HS diet significantly increased serum level of pro-inflammatory cytokines INF-γ, TNF-α, IL-9, and IL-17A levels, but also of anti-inflammatory cytokines IL-10 and TGF-β1. Relative amount of total SGK1 significantly increased, following the 7-day HS diet. Increased oxidative stress level, following HS diet, was negatively associated with the frequency of Treg cells. The increase in relative amount of total SGK1 in peripheral mononuclear cells following 7-day HS diet suggests lymphocyte (re)activation, in response to HS intake, resulting in enhanced production of pro-inflammatory (IL-17, INF-γ), but also anti-inflammatory cytokines (IL-10 and TGF-β1). Increased oxidative stress, due to HS loading, alters immune regulatory mechanisms, presumably via effects on Treg cells.

A wrinkle in time: circadian biology in pulmonary vascular health and disease

An often overlooked element of pulmonary vascular disease is time. Cellular responses to time, which are regulated directly by the core circadian clock, have only recently been elucidated. Despite an extensive collection of data regarding the role of rhythmic contribution to disease pathogenesis (such as systemic hypertension, coronary artery, and renal disease), the roles of key circadian transcription factors in pulmonary hypertension remain understudied. This is despite a large degree of overlap in the pulmonary hypertension and circadian rhythm fields, not only including shared signaling pathways, but also cell-specific effects of the core clock that are known to result in both protective and adverse lung vessel changes. Therefore, the goal of this review is to summarize the current dialogue regarding common pathways in circadian biology, with a specific emphasis on its implications in the progression of pulmonary hypertension. In this work, we emphasize specific proteins involved in the regulation of the core molecular clock while noting the circadian cell-specific changes relevant to vascular remodeling. Finally, we apply this knowledge to the optimization of medical therapy, with a focus on sleep hygiene and the role of chronopharmacology in patients with this disease. In dissecting the unique relationship between time and cellular biology, we aim to provide valuable insight into the practical implications of considering time as a therapeutic variable. Armed with this information, physicians will be positioned to more efficiently use the full four dimensions of patient care, resulting in improved morbidity and mortality of pulmonary hypertension patients.

Pathophysiological Mechanisms of Hypertension Development Induced by Fructose Consumption

During the past several decades, there has been a dramatic increase in fructose consumption worldwide in parallel with epidemics of metabolic diseases. Accumulating evidence has suggested that excessive fructose consumption...

Heart Angiotensin-Converting Enzyme and Angiotensin-Converting Enzyme 2 Gene Expression Associated With Male Sex and Salt-Sensitive Hypertension in the Dahl Rat

Angiotensin-converting enzyme 2 (ACE 2) in the heart including its sex dependency in the hypertensive heart, has not been much studied compared to ACE. In the present study, we used the Dahl salt-sensitive rat exposed to fructose and salt to model a hypertensive phenotype in males, females, and ovariectomized females. Blood pressure was measured by the tale-cuff technique in the conscious state. Expression of RAS-related genes ACE, ACE2, angiotensin II receptor type 1, Mas1, and CMA1 in the heart were quantified. The results revealed small but significant differences between male and female groups. The main results indicate the presence of a male preponderance for an increase in ACE and ACE2 gene expression. The results are in accordance with the role of androgens or male chromosomal complement in controlling the expression of the two ACE genes.

Perinatal High-Salt Diet Induces Gut Microbiota Dysbiosis, Bile Acid Homeostasis Disbalance, and NAFLD in Weanling Mice Offspring

A perinatal high-salt (HS) diet was reported to elevate plasma triglycerides. This study aimed to investigate the hypothesis that a perinatal HS diet predisposed offspring to non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of abnormal lipid metabolism, and the possible mechanism. Female C57BL/6 mice were fed a control diet (0.5% NaCl) or HS diet (4% NaCl) during pregnancy and lactation and their offspring were sacrificed at weaning. The perinatal HS diet induced greater variation in fecal microbial beta-diversity (β-diversity) and increased bacteria abundance of Proteobacteria and Bacteroides. The gut microbiota dysbiosis promoted bile acid homeostasis disbalance, characterized by the accumulation of lithocholic acid (LCA) and deoxycholic acid (DCA) in feces. These alterations disturbed gut barrier by increasing the expression of tight junction protein (Tjp) and occludin (Ocln), and increased systemic lipopolysaccharide (LPS) levels and hepatic inflammatory cytokine secretion (TNF-α and IL-6) in the liver. The perinatal HS diet also inhibited hepatic expression of hepatic FXR signaling (CYP7A1 and FXR), thus triggering increased hepatic expression of pro-inflammatory cytokines (TNF-α and IL-6) and hepatic lipid metabolism-associated genes (SREBP-1c, FAS, ACC), leading to unique characteristics of NAFLD. In conclusion, a perinatal HS diet induced NAFLD in weanling mice offspring; the possible mechanism was related to increased bacteria abundance of Proteobacteria and Bacteroides, increased levels of LCA and DCA in feces, and increased expressions of hepatic FXR signaling.

Ex Vivo High Salt Activated Tumor-Primed CD4+T Lymphocytes Exert a Potent Anti-Cancer Response

Cell based immunotherapy is rapidly emerging as a promising cancer treatment. A modest increase in salt (sodium chloride) concentration in immune cell cultures is known to induce inflammatory phenotypic differentiation. In our current study, we analyzed the ability of salt treatment to induce ex vivo expansion of tumor-primed CD4 (cluster of differentiation 4)+T cells to an effector phenotype. CD4+T cells were isolated using immunomagnetic beads from draining lymph nodes and spleens from tumor bearing C57Bl/6 mice, 28 days post-injection of Py230 syngeneic breast cancer cells. CD4+T cells from non-tumor bearing mice were isolated from splenocytes of 12-week-old C57Bl/6 mice. These CD4+T cells were expanded ex vivo with five stimulation cycles, and each cycle comprised of treatment with high salt (Δ0.035 M NaCl) or equimolar mannitol controls along with anti-CD3/CD28 monoclonal antibodies for the first 3 days, followed by the addition of interleukin (IL)-2/IL-7 cytokines and heat killed Py230 for 4 days. Ex vivo high salt treatment induced a two-fold higher Th1 (T helper type 1) expansion and four-fold higher Th17 expansion compared to equimolar mannitol treatment. Importantly, the high salt expanded CD4+T cells retained tumor-specificity, as demonstrated by higher in vitro cytotoxicity against Py230 breast cancer cells and reduced in vivo syngeneic tumor growth. Metabolic studies revealed that high salt treatment enhanced the glycolytic reserve and basal mitochondrial oxidation of CD4+T cells, suggesting a role of high salt in enhanced pro-growth anabolic metabolism needed for inflammatory differentiation. Mechanistic studies demonstrated that the high salt induced switch to the effector phenotype was mediated by tonicity-dependent transcription factor, TonEBP/NFAT5. Using a transgenic murine model, we demonstrated that CD4 specific TonEBP/NFAT5 knock out (CD4cre/creNFAT5flox/flox) abrogated the induction of the effector phenotype and anti-tumor efficiency of CD4+T cells following high salt treatment. Taken together, our data suggest that high salt-mediated ex vivo expansion of tumor-primed CD4+T cells could induce effective tumor specific anti-cancer responses, which may have a novel cell-based cancer immunotherapeutic application.

Transfer of Th17 from Adult Spontaneous Hypertensive Rats Accelerates Development of Hypertension in Juvenile Spontaneous Hypertensive Rats

Hypertension develops in the recipient rats that are transferred with the activated T helper (Th) 17 cells of the donor rats exposed to high-fructose or high-salt intake. This result suggests that a pathologic Th17 cell plays a role in the development and maintenance of hypertension. Here, we tested the hypothesis that the transfer of Th17 cells from adult spontaneous hypertensive rats (SHR) accelerates the development of hypertension in juvenile SHR. The tail-cuff method was used to measure systolic blood pressure. T cell (Th17 and regulatory T (Treg)) profiling was analyzed by flow cytometry. The expressions of Th17-related interleukin- (IL-) 17A and Treg-related IL-10 were measured by ELISA. Th17 cells isolated from adult SHR were intraperitoneally injected into juvenile recipient SHR and Wistar-Kyoto rats (WKY). SHR exhibited prominent development of hypertension at 15 weeks. The proportion of CD4⁺IL-17A⁺ (Th17) cells among Th cells increased whereas the proportion of CD4⁺FoxP3⁺ (Treg) cells decreased in SHR, as compared to WKY. The serum levels of IL-17A increased gradually with aging in SHR, but the serum levels of IL-10 did not. The serum levels of IL-17A and IL-10 seemed to be well related to the proportion of Th17 cells and Treg cells, respectively. Injection of Th17 cells isolated from adult SHR accelerates the development of hypertension in juvenile SHR but not in juvenile WKY though it increased the proportion of Th17 cells in juvenile recipient WKY and SHR. The transfer of Th17 cells from adult SHR accelerates the development of hypertension in juvenile SHR. These results implicate that the hypertension in SHR is ascribed to activation of Th17 cells.

The importance of bone marrow and the immune system in driving increases in blood pressure and sympathetic nerve activity in hypertension

NEW FINDINGS

What is the topic of this review? This manuscript provides a review of the current understanding of the role of the sympathetic nervous system in regulation of bone marrow-derived immune cells and the effect that the infiltrating bone marrow cells may have on perpetuation of the sympathetic over-activation in hypertension. What advances does it highlight? We highlight the recent advances in understanding of the neuroimmune interactions both peripherally and centrally as they relate to blood pressure control.

ABSTRACT

The sympathetic nervous system (SNS) plays a crucial role in maintaining physiological homeostasis, in part by regulating, integrating and orchestrating processes between many physiological systems, including the immune system. Sympathetic nerves innervate all primary and secondary immune organs, and all cells of the immune system express β-adrenoreceptors. In turn, immune cells can produce cytokines, chemokines and neurotransmitters capable of modulating neuronal activity and, ultimately, SNS activity. Thus, the essential role of the SNS in the regulation of innate and adaptive immune functions is mediated, in part, via β-adrenoreceptor-induced activation of bone marrow cells by noradrenaline. Interestingly, both central and systemic inflammation are well-established hallmarks of hypertension and its co-morbidities, including an inflammatory process involving the transmigration and infiltration of immune cells into tissues. We propose that physiological states that prolong β-adrenoreceptor activation in bone marrow can disrupt neuroimmune homeostasis and impair communication between the immune system and SNS, leading to immune dysregulation, which, in turn, is sustained via a central mechanism involving neuroinflammation.

Role of interleukin-23/interleukin-17 axis in T-cell-mediated actions in hypertension

Current knowledge suggests that hypertension is in part mediated by immune mechanisms. Both interleukin (IL)-23 and IL-17 are up-regulated in several experimental hypertensive rodent models, as well as in hypertensive humans in observational studies. Recent preclinical studies have shown that either IL-23 or IL-17A treatment induce blood pressure elevation. However, the IL-23/IL-17 axis has not been a major therapeutic target in hypertension, unlike in other autoimmune diseases. In this review, we summarize current knowledge on the role of these cytokines in immune mechanisms contributing to hypertension, and discuss the potential of IL-23/IL-17-targeted therapy for treatment of hypertension.