Salt and hypertension in diabetes

The role of gut microbiota in the development of salt-sensitive hypertension and the possible preventive effect of exercise

INTRODUCTION

The aim of the present study is to analyze the data indicating an association between high salt intake and the gastrointestinal microbiota in the development of salt-sensitive hypertension in animals and men. It is also, to discuss the preventive effects of exercise on gut-induced hypertension by favorably modifying the composition of gut microbiota.

AREAS COVERED

Salt sensitivity is quite common, accounting for 30%-60% in hypertensive subjects. Recently, a novel cause for salt-sensitive hypertension has been discovered through the action of gut microbiota by the secretion of several hormones and the action of short chain fatty acids (SCFAs). In addition, recent studies indicate that exercise might favorably modify the adverse effects of gut microbiota regarding their effects on BP. To identify the role of gut microbiota on the incidence of hypertension and CVD and the beneficial effect of exercise, a Medline search of the English literature was conducted between 2018 and 2023 and 42 pertinent papers were selected.

EXPERT OPINION

The analysis of data from the selected papers disclosed that the gut microbiota contribute significantly to the development of salt-sensitive hypertension and that exercise modifies their gut composition and ameliorates their adverse effects on BP.

Salt Intake in Adults with Diabetes and Hypertension: The Longitudinal Study of Adult Health-Brasil Study

Background and Objective: Hypertension and type-2 diabetes are strong risk factors for cardiovascular diseases, and their management requires lifestyle changes, including a shift in dietary habits. The consumption of salt has increased in the last decades in some countries, but its association with type-2 diabetes remains unknown. Thus, we aimed to estimate the amount of salt intake among adults with and without diabetes and to assess whether concomitant hypertension and diabetes are associated with higher salt intake. Methods: Data from 11,982 adults 35-74 years of age enrolled in the baseline of the Longitudinal Study of Adult Health-Brasil study (2008-2010) were studied. A clinical and anthropometric evaluation was performed, and their daily salt intake was estimated by the overnight 12-hr urine sodium excretion. Results: Salt intake (gram per day) was higher in participants with diabetes as compared with those without diabetes, regardless of sex (men: 14.2 ± 6.4 vs. 12.4 ± 5.6, P < 0.05; women: 10.5 ± 4.8 vs. 9.1 ± 4.1, P < 0.05). However, salt intake is high in participants with fasting glucose ≥126 mg/dL or HbA1c ≥6.5%, but not in participants with blood glucose 2 hr after the glucose tolerance test ≥200 mg/dL. When hypertension and diabetes coexisted, salt consumption was higher than among people without these conditions. The prevalence of hypertension increased with increasing salt intake in women with diabetes, but not in men with this condition. Conclusions: Our findings highlight the high consumption of salt in individuals with diabetes and/or hypertension, and the need for effective strategies to reduce salt consumption in these groups of increased risk for major cardiovascular events, especially in women.

O-Linked GlcNAcylation mediates the inhibition of proximal tubule (Na++K+)ATPase activity in the early stage of diabetes mellitus

BACKGROUND

Diabetic kidney disease (DKD) is a severe complication of diabetes mellitus (DM). It has been proposed that modifications in the function of proximal tubule epithelial cells (PTECs) precede glomerular damage during the onset of DKD. This study aimed to identify modifications in renal sodium handling in the early stage of DM and its molecular mechanism.

METHODS

Streptozotocin (STZ)-induced diabetic BALB/c mice (STZ group) and LLC-PK1 cells, a model of PTECs, were used. All parameters were assessed in the 4th week after an initial injection of STZ.

RESULTS

Early stage of DKD was characterized by hyperfiltration and PTEC dysfunction. STZ group exhibited increased urinary sodium excretion due to impairment of tubular sodium reabsorption. This was correlated to a decrease in cortical (Na++K+)ATPase (NKA) α1 subunit expression and enzyme activity and an increase in O-GlcNAcylation. RNAseq analysis of patients with DKD revealed an increase in expression of the glutamine-fructose aminotransferase (GFAT) gene, a rate-limiting step of hexosamine biosynthetic pathway, and a decrease in NKA expression. Incubation of LLC-PK1 cells with 10 μM thiamet G, an inhibitor of O-GlcNAcase, reduced the expression and activity of NKA and increased O-GlcNAcylation. Furthermore, 6-diazo-5-oxo-L-norleucine (DON), a GFAT inhibitor, or dapagliflozin, an SGLT2 inhibitor, avoided the inhibitory effect of HG on expression and activity of NKA associated with the decrease in O-GlcNAcylation.

CONCLUSION

Our results show that the impairment of tubular sodium reabsorption, in the early stage of DM, is due to SGLT2-mediated HG influx in PTECs, increase in O-GlcNAcylation and reduction in NKA expression and activity.

SGLT2 inhibition effect on salt-induced hypertension, RAAS, and Na+ transport in Dahl SS rats

Na+-glucose cotransporter-2 (SGLT2) inhibitors are the new mainstay of treatment for diabetes mellitus and cardiovascular diseases. Despite the remarkable benefits, the molecular mechanisms mediating the effects of SGLT2 inhibitors on water and electrolyte balance are incompletely understood. The goal of this study was to determine whether SGLT2 inhibition alters blood pressure and kidney function via affecting the renin-angiotensin-aldosterone system (RAAS) and Na+ channels/transporters along the nephron in Dahl salt-sensitive rats, a model of salt-induced hypertension. Administration of dapagliflozin (Dapa) at 2 mg/kg/day via drinking water for 3 wk blunted the development of salt-induced hypertension as evidenced by lower blood pressure and a left shift of the pressure natriuresis curve. Urinary flow rate, glucose excretion, and Na+- and Cl--to-creatinine ratios increased in Dapa-treated compared with vehicle-treated rats. To define the contribution of the RAAS, we measured various hormones. Despite apparent effects on Na+- and Cl--to-creatinine ratios, Dapa treatment did not affect RAAS metabolites. Subsequently, we assessed the effects of Dapa on renal Na+ channels and transporters using RT-PCR, Western blot analysis, and patch clamp. Neither mRNA nor protein expression levels of renal transporters (SGLT2, Na+/H+ exchanger isoform 3, Na+-K+-2Cl- cotransporter 2, Na+-Cl- cotransporter, and α-, β-, and γ-epithelial Na+ channel subunits) changed significantly between groups. Furthermore, electrophysiological experiments did not reveal any difference in Dapa treatment on the conductance and activity of epithelial Na+ channels. Our data suggest that SGLT2 inhibition in a nondiabetic model of salt-sensitive hypertension blunts the development of salt-induced hypertension by causing glucosuria and natriuresis without changes in the RAAS or the expression or activity of the main Na+ channels and transporters.NEW & NOTEWORTHY The present study indicates that Na+-glucose cotransporter-2 (SGLT2) inhibition in a nondiabetic model of salt-sensitive hypertension blunts the development and magnitude of salt-induced hypertension. Chronic inhibition of SGLT2 increases glucose and Na+ excretion without secondary effects on the expression and function of other Na+ transporters and channels along the nephron and hormone levels in the renin-angiotensin-aldosterone system. These data provide novel insights into the effects of SGLT2 inhibitors and their potential use in hypertension.

Impact of Sociodemographic Characteristics, Lifestyle, and Obesity on Coexistence of Diabetes and Hypertension: A Structural Equation Model Analysis amongst Chinese Adults

Background

In general, given the insufficient sample size, considerable literature has been found on single studies of diabetes and hypertension and few studies have been found on the coexistence of diabetes and hypertension (CDH) and its influencing factors with a large range of samples. This study aimed to establish a structural equation model for exploring the direct and indirect relationships amongst sociodemographic characteristics, lifestyle, obesity, and CDH amongst Chinese adults.

Methods

A cross-sectional study was conducted in a representative sample of 25356 adults between June 1, 2015, and September 30, 2018, in Hubei province, China. Confirmatory factor analysis was initially conducted to test the latent variables. A structural equation model was then performed to analyse the association between latent variables and CDH.

Results

The total prevalence of CDH was 2.8%. The model paths indicated that sociodemographic characteristics, lifestyle, and obesity were directly associated with CDH, and the effects were 0.187, 0.739, and 0.353, respectively. Sociodemographic characteristics and lifestyle were also indirectly associated with CDH, and the effects were 0.128 and 0.045, respectively. Lifestyle had the strongest effect on CDH (β = 0.784, P < 0.001), followed by obesity (β = 0.353, P < 0.001) and sociodemographic characteristics (β = 0.315, P < 0.001). All paths of the model were significant (P < 0.001).

Conclusion

CDH was significantly associated with sociodemographic characteristics, lifestyle, and obesity amongst Chinese adults. The dominant predictor of CDH was lifestyle. Targeting these results might develop lifestyle and weight loss intervention to prevent CDH according to the characteristics of the population.

Association study of fasting blood glucose and salt sensitivity of blood pressure in community population: The EpiSS study

BACKGROUND AND AIMS

To evaluate the association between fasting blood glucose (FBG) and salt sensitivity of blood pressure (SSBP).

METHODS AND RESULTS

This study is based on the baseline survey of systemic epidemiology of salt sensitivity study. Subjects were classified into salt sensitive (SS) and salt resistant groups according to blood pressure (BP) changes during the modified Sullivan's acute oral saline load and diuresis shrinkage test. Multivariate logistic and linear regression were used to evaluate associations between FBG with SS or BP changes. A total of 2051 participants were included in the analyses with 581 (28.33%) for SS. Multiple analysis showed that for every interquartile range increase in FBG, the OR (95%CI) for SS was 1.140 (1.069, 1.215), β (95%CI) for mean arterial pressure change (ΔMAP₁), systolic and diastolic BP changes during saline load were 0.421 (0.221, 0.622), 0.589 (0.263, 0.914) and 0.340 (0.149, 0.531), respectively. Compared to the lowest FBG quartile (Q₁), the OR (95%CI) for SS in Q₃ and Q₄ were 1.342 (1.014, 1.776) and 1.577 (1.194, 2.084), respectively. Compared to subjects with normal FBG, the β (95%CI) for ΔMAP₁ was 0.973 (0.055, 1.891) in subjects with impaired FBG, and was 1.449 (0.602, 2.296) in patients with diabetes mellitus. Stratified analyses showed significant and stronger associations between FBG with SSBP in youngers, females, hypertensives, non-diabetics, non-current smokers and non-current drinkers.

CONCLUSION

Our findings suggest FBG is an independent, dose-dependent associated factor for SSBP, and prevention of SS focusing on controlling FBG elevation in the early stage is important.

Host Immune Defense upon Fungal Infections with Mucorales: Pathogen-Immune Cell Interactions as Drivers of Inflammatory Responses

During the last few decades, mucormycosis has emerged as one of the most common fungal infections, following candidiasis and aspergillosis. The fungal order responsible for causing mucormycosis is the Mucorales. The main hallmarks of this infection include the invasion of blood vessels, infarction, thrombosis, and tissue necrosis, which are exhibited at the latest stages of the infection. Therefore, the diagnosis is often delayed, and the rapid progression of the infection severely endangers the life of people suffering from diabetes mellitus, hematological malignancies, or organ transplantation. Given the fact that mortality rates for mucormycosis range from 40 to 80%, early diagnosis and novel therapeutic strategies are urgently needed to battle the infection. However, compared to other fungal infections, little is known about the host immune response against Mucorales and the influence of inflammatory processes on the resolution of the infection. Hence, in this review, we summarized our current understanding of the interplay among pro-inflammatory cytokines, chemokines, and the host-immune cells in response to mucoralean fungi, as well as their potential use for immunotherapies.