American Journal of Hypertension最新文献

Background: Salt-sensitive hypertension is often more prone to induce damage to target organs such as the heart and kidneys. Abundant recent studies have demonstrated a close association between ferroptosis and cardiovascular diseases. Therefore, we hypothesize that ferroptosis may be closely associated with organ damage in salt-sensitive hypertension. This study aimed to investigate whether ferroptosis is involved in the occurrence and development of myocardial fibrosis and renal fibrosis in salt-sensitive hypertensive rats.

Methods: Ten 7-week-old male Dahl salt-sensitive (Dahl-SS) rats were adaptively fed for 1 week, then randomly divided into two groups and fed either a normal diet (0.3% NaCl, normal diet group) or a high-salt diet (8% NaCl, high-salt diet group) for 8 weeks. Blood pressure of the rats was observed, and analysis of the hearts and kidneys of Dahl-SS rats was conducted via hematoxylin-eosin (HE) staining, Masson staining, Prussian blue staining, transmission electron microscopy, tissue iron content detection, malondialdehyde content detection, immunofluorescence, and Western blot.

Results: Compared to the normal diet group, rats in the high-salt diet group had increases in systolic blood pressure and diastolic blood pressure (P < 0.05); collagen fiber accumulation was observed in the heart and kidney tissues (P < 0.01), accompanied by alterations in mitochondrial ultrastructure, reduced mitochondrial volume, and increased density of the mitochondrial double membrane. Additionally, there were significant increases in both iron content and malondialdehyde levels (P < 0.05). Immunofluorescence and Western blot results both indicated significant downregulation (P < 0.05) of xCT and GPX4 proteins associated with ferroptosis in the high-salt diet group.

Conclusions: Ferroptosis is involved in the damage and fibrosis of the heart and kidney tissues in salt-sensitive hypertensive rats.

Backround: Complement activation may facilitate hypertension through its effects on immune responses. The anaphylatoxin C5a, a major inflammatory effector, binds to the C5a receptors 1 and 2 (C5aR1, C5aR2). We have recently shown that C5aR1-/- mice have reduced hypertensive renal injury. The role of C5aR2 in hypertension is unknown.

Methods: For examination of C5aR2 expression on infiltrating and resident renal cells a tandem dye Tomato-C5aR2 knock-in reporter mouse was used. Human C5aR2 expression was analyzed in a single-cell RNAseq data set from the kidneys of hypertensive patients. Finally, we examined the effect of angiotensin II-induced hypertension in C5aR2-deficient mice.

Results: Flow cytometric analysis of leukocytes isolated from kidneys of the reporter mice showed that dendritic cells are the major C5aR2-expressing population (34%) followed by monocyte/macrophages (30%) and neutrophils (14%). Using confocal microscopy C5aR2 was not detected in resident renal or cardiac cells. In the human kidney, C5aR2 was also mainly found in monocytes, macrophages, and dendritic cells with a significantly higher expression in hypertension (P < 0.05). Unilateral nephrectomy was performed followed by infusion of Ang II (0.75 ng/g/min) and a high salt diet in wildtype (n = 18) and C5aR2-deficient mice (n = 14). Blood pressure, renal injury (albuminuria, glomerular filtration rate, glomerular and tubulointerstitial injury, inflammation), and cardiac injury (cardiac fibrosis, heart weight, gene expression) did not differ between hypertensive wildtype and C5aR2-/- mice.

Conclusions: In summary, C5aR2 is mainly expressed in myeloid cells in the kidney in mice and humans but its deficiency has no effect on Ang II-induced hypertensive injury.

Background: Previous studies with several limitations have comparatively analyzed the relationship between ambulatory blood pressure (BP) and self-measured BP and biomarkers of organ damage. This study extends this line of research by examining the relationship between ambulatory and self-measured BP and cardiac, renal, and atherosclerotic biomarkers in outpatients at cardiovascular risk.

Methods: In 1,440 practice outpatients who underwent office, ambulatory, and self-measured BP monitoring, we assessed the relationships of each BP with organ damage biomarkers including b-type natriuretic peptide (BNP), echocardiographic left ventricular mass index (LVMI), urine albumin-creatinine ratio (UACR), and brachial-ankle pulse wave velocity (baPWV).

Results: In the comparison of correlation, self-measured systolic BP (SBP) was more strongly correlated to log-transformed (Ln) BNP (n = 1,435; r = 0.123 vs. r = -0.093, P < 0.001), LVMI (n = 1,278; r = 0.223 vs. r = 0.094, P < 0.001), Ln-UACR (n = 1,435; r = 0.244 vs. r = 0.154, P = 0.010), and baPWV (n = 1,360; r = 0.327 vs. r = 0.115, P < 0.001) than daytime ambulatory SBP. In the linear regression models including office, ambulatory, and self-measured SBP, only self-measured SBP was significantly related to Ln-BNP (P = 0.016) and LVMI (P < 0.001). In the logistic regression models for the top quartile of LVMI, adding self-measured SBP improved the model predictability (P = 0.027), but adding daytime ambulatory SBP did not. However, adding daytime ambulatory SBP improved the model predictability in the logistic model for the top quartile of baPWV including office and self-measured SBP (P = 0.030).

Conclusions: Our study findings suggested that self-measured BP was associated with cardiac biomarkers independent of ambulatory BP.

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.