Ischemic Conditioning Reduces Inflammatory Signaling
Ischemic conditioning involves reducing the blood flow to part of the body for a period of time, such as to limbs via use of a tourniquet. When carried out correctly, the right degree of restriction for the right length of time, this provokes a beneficial stress response in cells that is similar in some ways to that produced by exercise. Here, researchers show that ischemic conditioning reduces the inflammatory signaling and state of chronic inflammation that contributes to many age-related conditions, including the age-related hypertension that the is the focus on these studies.
Hypertension is a leading risk factor for cardiovascular, cerebrovascular, and many other diseases. Vascular remodeling results from blood pressure elevation, and progressively becomes a crucial cause of hypertension. However, during vascular remodeling no symptoms except occasional blood pressure elevation are observed. Neither attention nor treatment would be considered until the diagnosis of hypertension is established. Thus, timely therapy is urgent for the prevention and treatment of early-stage vascular remodeling.
Vascular remodeling results initially from passive physiological adaptation to blood pressure changes, then progresses into an active pathological process caused by elevated blood pressure, aging, and several other factors. An earlier study showed the critical role of inflammation in the pathological changes involved in vascular remodeling. Emerging evidence indicates that infiltrating proinflammatory cells are essential for the migration and infiltration of inflammatory factors. Several inflammatory factors were shown to affect blood pressure and vascular function leading to vascular remodeling and dysfunction. Thus, it is reasonable to hypothesize that by regulating inflammatory cells and their environment might aid in the treatment and prevention of vascular remodeling and hypertension-related vascular diseases.
Limb remote ischemic conditioning (LRIC) is a physiological treatment that protects against acute ischemic events and traumatic injury. Chronic remote ischemic conditioning simulates regular exercise and exerts its protective effect via humoral and immunological regulation. Some clinical cases reported that LRIC could decrease blood pressure. However, studies on whether LRIC positively affects chronic vascular remodeling and blood pressure are scant. Considering all the available evidence, we hypothesize that LRIC would exert a protective effect on hypertension-related vascular remodeling, thus delaying vascular stiffness and aging caused by structural remodeling.
In this study, LRIC of rats was performed once a day for 6-weeks. Blood pressure, vascular remodeling, and inflammation were compared among normotensive Wistar-Kyoto rats (WKY), WKY RIC group, spontaneously hypertensive rat (SHR) control group, and SHR RIC. LRIC treatment decreased blood pressure in SHR. 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. LRIC decreased proinflammatory factors while increasing the anti-inflammatory factors in the circulation. LRIC decreased circulating monocyte and natural killer T-cell levels.
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 and improved vascular stiffness in patients. In conclusion, long term LRIC could decrease blood pressure and ameliorate vascular remodeling via inflammation regulation.