The role of brain macrophages in hypertension response sensitization

Hypertension is a condition where there is a sustained increase in the arterial pressure. More than one in three adults in the US has hypertension. Medication only controls ~25% of these individuals, putting a huge population at increased risk of heart disease and stroke. Adult males have higher prevalence than females of developing hypertension, but this is reversed in older adults. Studies in rodents have shown that the experimentally-induced hypertensive response can be sensitized. That is, a previous exposure to risk factors such as early life stress, high fat diet, and systemic inflammation can lead to a potentiated increase in mean arterial pressure in response to later challenges. This hypertensive response sensitization (HTRS) is demonstrated in male rodents but not in female rodents.

I studied the role of microglia, the brain resident immune cells, in HTRS in rodents. My work demonstrated a difference in microglia morphology in untreated male and female rats and also uncovered a change in microglia morphology in male rats that were exposed to low dose of angiotensin-II, a hormone that regulates blood pressure. Utilizing a pharmacological drug PLX-3397 that reversibly depletes microglia, my findings demonstrated that brain immune cells are necessary for full expression of HTRS. These observations support a role for the brain immune cells in the modulation of factors that affect the development of essential hypertension.