Low-grade inflammation and arterial stiffness in the elderly

Spironolactone protects against hypertension-induced renal fibrosis by promoting autophagy and inhibiting the NLRP3 inflammasome

INTRODUCTION

We aimed to investigate the mechanism by which spironolactone protects against hypertensive renal fibrosis.

METHODS

For in-vivo experiments, we established Control, SHR, and SHR+spironolactone (20 mg/kg/day) groups. For in-vitro experiments, we established Control, TGF-β1-induced (10 ng/ml), and spironolactone (1 μmol/l) intervention groups. Renal function and serum potassium, estradiol, testosterone, and plasma aldosterone levels were assessed, along with autophagy indicators LC3 and p62, and NLRP3 inflammasome-related proteins (NLRP3, caspase-1, IL-1β and IL-18). Additionally, changes in macrophage polarization and T cell and dendritic cell populations were determined.

RESULTS

20 mg/kg/day of spironolactone effectively maintained systolic pressure and renal function by lowering aldosterone levels and significantly reducing testosterone levels. Hypertensive renal fibrosis was predominant in the glomeruli, tubules, and interstitium, and was associated with autophagy inhibition in renal tubules, NLRP3 inflammasome activation, both M1 and M2 macrophage polarization, with a predominant effect on M1 polarization, decreased CD4+ T cell population and CD4/CD8 ratio, and increased CD8+ T cell and dendritic cell population. Autophagy negatively regulated the NLRP3 inflammasome. Spironolactone inhibited both M1 and M2 macrophages polarization, mainly M1 macrophage polarization, reduced CD8+ T and dendritic cell population, increased CD4+ T cell population, negatively regulated the release of NLRP3 inflammasome-related proteins in macrophages, and restored autophagy in the glomeruli and renal tubules.

CONCLUSION

Spironolactone acts on sites where the mineralocorticoid receptor is present. A dose of 20 mg/kg/day spironolactone is well tolerated and protects against hypertension-induced renal fibrosis by restoring autophagy and suppressing NLRP3 inflammasome activation.

Nonlinear relationship with saturation effect observed between neutrophil to high-density lipoprotein cholesterol ratio and atherosclerosis in a health examination population: a cross-sectional study

Background

The relationships between inflammatory indexes and atherosclerosis as well as those between blood lipid indexes and atherosclerosis have been widely studied, but the relationship between the neutrophil to high-density lipoprotein cholesterol ratio (NHR) and atherosclerosis had not been investigated until the present study.

Methods

For this cross‐sectional study, we continuously collected data from a health examination population in the Second Hospital of Hebei Medical University from January 2012 to December 2017 (N = 1978). The collected data included clinical data, hematological indexes, and brachial-ankle pulse wave velocity (Ba-PWV). Atherosclerosis was defined as Ba-PWV ≥ 1400 cm/s. The relationship between the NHR and atherosclerosis was explored via univariate regression analysis, multivariate regression analysis, smoothing function analysis, and analysis of a threshold saturation effect.

Results

Among 1978 participants, the mean age was 54 years, 1189 participants (60.11%) were male, and 1103 (55.76%) had a history of atherosclerosis. Univariate analysis showed a positive association between the NHR and atherosclerosis [odds ratio (OR) = 1.19, 95% confidence interval (CI): 1.11–1.27, P < 0.01], and this positive association remained significant on multivariate analyses with adjustments for confounding factors (OR = 1.14, 95% CI: 1.06–1.24, P < 0.01). Generalized additive model results revealed a non-linear relationship with a saturation effect between the NHR and atherosclerosis, with a threshold at 3.32. At values ≤ 3.32, the NHR was positively associated with atherosclerosis, but the association was not statistically significant for values > 3.32.

Conclusion

A nonlinear relationship with a certain saturation effect was observed between the NHR and atherosclerosis in a health examination population.

Peripheral arterial stiffness is associated with higher baseline plasma uric acid: A prospective cohort study

This prospective cohort study aimed at identifying association between uric acid (UA) and peripheral arterial stiffness. A prospective cohort longitudinal study was performed according to an average of 4.8 years’ follow-up. The demographic data, anthropometric parameters, peripheral arterial stiffness (carotid-radial pulse-wave velocity, cr-PWV) and biomarker variables including UA were examined at both baseline and follow-up. Pearson’s correlations were used to identify the associations between UA and peripheral arterial stiffness. Further logistic regressions were employed to determine the associations between UA and arterial stiffness. At the end of follow-up, 1447 subjects were included in the analyses. At baseline, cr-PWV (r = 0.200, p < 0.001) was closely associated with UA. Furthermore, the follow-up cr-PWV (r = 0.145, p < 0.001) was also strongly correlated to baseline UA in Pearson’s correlation analysis. Multiple regressions also indicated the association between follow-up cr-PWV (β = 0.493, p = 0.013) and baseline UA level. Logistic regressions revealed that higher baseline UA level was an independent predictor of arterial stiffness severity assessed by cr-PWV at follow-up cross-section. Peripheral arterial stiffness is closely associated with higher baseline UA level. Furthermore, a higher baseline UA level is an independent risk factor and predictor for peripheral arterial stiffness.

Influence of Thoracic Aortic Inflammation and Calcifications on Arterial Stiffness and Cardiac Function in Older Subjects

BACKGROUND

Vascular aging is accompanied by gradual remodeling affecting both arterial and cardiac structure and mechanical properties. Hypertension is suggested to exert pro-inflammatory actions enhancing arterial stiffness.

OBJECTIVE

To determine the influence of thoracic aortic inflammation and calcifications on arterial stiffness and cardiac function in hypertensive and normotensive older subjects.

DESIGN

A prospective study.

SETTING

An acute geriatrics ward of the University Hospital of Nancy in France.

SUBJECTS

Thirty individuals ≥ 65 years were examined, including 15 hypertensive subjects and 15 controls well-matched for age and sex.

MEASUREMENTS

Applanation tonometry was used to measure aortic pulse wave velocity (AoPWV) and carotid/brachial pulse pressure amplification (PPA). Left ventricular parameters were measured with magnetic resonance imaging. Local thoracic aortic inflammation and calcification were measured by 18 F-fluorodeoxyglucose positron emission tomography/computed tomography imaging. Biomarkers of low-grade inflammation were also quantified.

RESULTS

AoPWV was higher in elderly hypertensive subjects comparatively to normotensive controls (15.5±5.3 vs. 11.9±2.5, p=0.046), and hypertensives had a higher calcification volume. In the overall population, calcifications of the thoracic descending aorta and inflammation of the ascending aorta accounted for respectively 18.1% (p=0.01) and 9.6% (p=0.07) of AoPWV variation. Individuals with high levels of calcifications and/or inflammation had higher AoPWV (p=0.003). Inflammation had a negative effect on PPA explaining 13.8% of its variation (p<0.05).

CONCLUSION

This study highlights the importance of local ascending aortic inflammation as a potential major actor in the determination of PPA while calcifications and hypertension are more linked to AoPWV. Assessment of PPA in the very elderly could provide complementary information to improve diagnostic and therapeutic strategies targeting ascending aortic inflammation.

Neuroinflammation and oxidative stress in rostral ventrolateral medulla contribute to neurogenic hypertension induced by systemic inflammation

Background

In addition to systemic inflammation, neuroinflammation in the brain, which enhances sympathetic drive, plays a significant role in cardiovascular diseases, including hypertension. Oxidative stress in rostral ventrolateral medulla (RVLM) that augments sympathetic outflow to blood vessels is involved in neural mechanism of hypertension. We investigated whether neuroinflammation and oxidative stress in RVLM contribute to hypertension following chronic systemic inflammation.

Methods

In normotensive Sprague-Dawley rats, systemic inflammation was induced by infusion of Escherichia coli lipopolysaccharide (LPS) into the peritoneal cavity via an osmotic minipump. Systemic arterial pressure and heart rate were measured under conscious conditions by the non-invasive tail-cuff method. The level of the inflammatory markers in plasma or RVLM was analyzed by ELISA. Protein expression was evaluated by Western blot or immunohistochemistry. Tissue level of superoxide anion (O₂^·-) in RVLM was determined using the oxidation-sensitive fluorescent probe dihydroethidium. Pharmacological agents were delivered either via infusion into the cisterna magna with an osmotic minipump or microinjection bilaterally into RVLM.

Results

Intraperitoneal infusion of LPS (1.2 mg/kg/day) for 14 days promoted sustained hypertension and induced a significant increase in plasma level of C-reactive protein, tumor necrosis factor-α (TNF-α), or interleukin-1β (IL-1β). This LPS-induced systemic inflammation was accompanied by activation of microglia, augmentation of IL-1β, IL-6, or TNF-α protein expression, and O₂^·- production in RVLM, all of which were blunted by intracisternal infusion of a cycloxygenase-2 (COX-2) inhibitor, NS398; an inhibitor of microglial activation, minocycline; or a cytokine synthesis inhibitor, pentoxifylline. Neuroinflammation in RVLM was also associated with a COX-2-dependent downregulation of endothelial nitric oxide synthase and an upregulation of intercellular adhesion molecule-1. Finally, the LPS-promoted long-term pressor response and the reduction in expression of voltage-gated potassium channel, Kv4.3 in RVLM were antagonized by minocycline, NS398, pentoxifylline, or a superoxide dismutase mimetic, tempol, either infused into cisterna magna or microinjected bilaterally into RVLM. The same treatments, on the other hand, were ineffective against LPS-induced systemic inflammation.

Conclusion

These results suggest that systemic inflammation activates microglia in RVLM to induce COX-2-dependent neuroinflammation that leads to an increase in O₂^·- production. The resultant oxidative stress in RVLM in turn mediates neurogenic hypertension.