Ischemic Conditioning Ameliorated Hypertension and Vascular Remodeling of Spontaneously Hypertensive Rat via Inflammatory Regulation

Abstract

Vascular remodeling is an initial step in the development of hypertension. Limb remote ischemic conditioning (LRIC) is a physiological treatment that induces endogenous protective effect during acute ischemic injury. However, the impact of long-term LRIC on hypertension, a chronic disease, is unknown. In this study, we aimed to investigate the LRIC effect on blood pressure and vascular remodeling in spontaneously hypertensive rat (SHR) model and patients with prehypertension and early-stage hypertension. LRIC of rats was performed once a day for 6-weeks. Blood pressure, vascular remodeling (cross-sectional area, extracellular deposition, and smooth muscle cell area), inflammation (inflammatory factors, and inflammatory cells) were compared among normotensive Wistar-Kyoto rats (WKY), WKY RIC group, SHR control group, and SHR RIC. Long-term LRCI treatment (twice a day for 4-weeks) was performed on patients with prehypertension or early-stage hypertension. Blood pressure and pulse wave velocity (PWV) were analyzed before and after LRIC treatment. LRIC treatment decreased blood pressure in SHR (n = 9-10). LRIC ameliorated vascular remodeling by decreasing cross-sectional area, suppressing deposition of the extracellular matrix, and hypertrophy of smooth muscle cell in conduit artery and small resistance artery (n = 7). LRIC decreased proinflammatory factors while increasing the anti-inflammatory factors in the circulation (n = 5). LRIC decreased circulating monocyte and natural killer T-cell levels (n = 5). Furthermore, LRIC treatment decreased blood pressure and improved vascular stiffness in patients (n = 20). In conclusion, long term LRIC could decrease blood pressure and ameliorate vascular remodeling via inflammation regulation. LRIC could be a preventive treatment for people with blood pressure elevation or prehypertension.

Keywords: hypertension; inflammation; limb remote ischemic preconditioning; vascular remodeling.

Conflict of interest statement

Conflicts of Interest The authors declare no conflict of interest.

copyright: © 2021 Gao et al.

Figures

Figure 1.

Effect of LRIC on blood pressure in SHR and WKY. (A) Representative sketches of this experiment. (B) Heart rate and the bodyweight of each group. Systolic blood pressure (SBP) (C), diastolic blood pressure (DBP) (D), and mean blood pressure (MBP) (E) of each group over 6-weeks. Data are expressed as mean ± SD, * P

Figure 2.

LRIC treatment ameliorated hypertrophic vascular remodeling of conducting artery and small resistance artery. (A) H&E staining of the thoracic aorta (TA) and second-order mesenteric artery (MEA). (B) Tunica media area and the wall thickness of TA and MEA of each group. Data are expressed as mean ± SD, * P

Figure 3.

LRIC treatment ameliorated hypertrophic vascular remodeling of middle cerebral artery and basilar artery. (A) H&E staining of the middle cerebral artery (MCA) and basilar artery (BA). (B) Media area of MCA and BA of each group. Data are expressed as mean ± SD, * P

Figure 4.

LRIC suppressed the production of the extracellular matrix of the conducting artery. Sirius-red (A) and VEG staining (B) of TA. (C) Collagen I, Collagen III, and elastic fiber area of TA. Data are expressed as mean ± SD, * P

Figure 5.

LRIC suppressed the production of the extracellular matrix of the small resistance artery. Sirius-red (A) and VEG staining (B) of MEA. (C) Collagen I, Collagen III, and elastic fiber area of MEA. Data are expressed as mean ± SD, * P

Figure 6.

LRIC suppressed smooth muscle cell hypertrophy of small resistance artery. (A) Immunostaining of smooth muscle actin of the TA and MEA. SMC area (B) and fluorescence intensity (C) in TA of each group. SMC area (D) and fluorescence intensity (E) in MEA of each group. Data are expressed as mean ± SD, * P

Figure 7.

LRIC treatment regulated circulating pro-inflammatory and anti-inflammatory factors. (A) pro-inflammatory cytokines CXCL1, TNFα, IL-1β, IFNγ,IL-5, and IL-6 levels in plasma. (B) anti-inflammatory cytokines IL-10, IL-13, and IL-4 levels in plasma. Data are expressed as mean ± SD, * P

Figure 8.

LRIC treatment regulated inflammatory immunocytes in circulation. (A) Flow cytometry analysis of CD172a+, CD43+ 172a+, CD43++ 172a+, and CD3+CD161a+ cells in the circulation. (B) level of monocyte, classic monocyte, non-classic monocyte, and natural killer T cells in circulation of each group. Data are expressed as mean ± SD, * P

Figure 9.

Hypertensive patient tolerance of LRIC. (A) The percentage of completed and uncompleted cycles. (B) The percentage of 90% and 80% completed patients. (C) The reasons for uncompleted cycles. (D) The percentage of completed cycles in each week.

Figure 10.

Long term LRIC decreased blood pressure and ameliorated conducting artery PWV. (A) Systolic blood pressure before and after LRIC treatment. (B) Diastolic blood pressure before and after LRIC treatment. (C) mean blood pressure before and after LRIC treatment. (D) PWV of left and right sides before and after LRIC treatment. * P