Decreased toll-like receptor 4 and CD11b/CD18 expression on peripheral monocytes of hypertensive patients correlates with a lesser extent of endothelial damage: a preliminary study

Background: Low-grade chronic inflammation is recognized to contribute to the physiopathology of arterial hypertension. Therefore, this study aimed to assess the pro-inflammatory phenotype of peripheral monocytes of hypertensive patients by analyzing Toll-like receptor 4 (TLR4) and CD11b/CD18 surface expression. In the second part, the influence of phenotypic alterations of monocytes on the endothelial status reflected by circulating endothelial cells (CECs) was evaluated. Patients: The study included 60 patients with arterial hypertension, who were divided into two subgroups based on the disease severity according to the applicable criteria. The mild hypertension and resistant hypertension groups included 30 patients each. The control group consisted of 33 normotensive volunteers matched for age and sex. Results: Both in the entire group of patients and individual subgroups, reduced surface expression of TLR4 and CD11b/CD18 was found compared to normotensive volunteers. A reduced percentage of monocytes with the CD14(+) TLR4(+) immunophenotype was correlated with a lower MFI level of CD18 and CD11b in the entire group of patients and after division only in the mild hypertension group. Reduced surface expression of TLR4 in hypertensive patients correlated with a lower number of CECs. This relationship was not observed in the resistant hypertension group; instead, an independent effect of reduced CD11b/ CD18 expression on the reduction of CEC number was demonstrated. Conclusion: Our preliminary study showed for the first time that hypertension of varying severity is accompanied by phenotypic changes in monocytes, manifested by reduced surface expression of both TLR4 and CD11b/ CD18. These phenotypic changes were associated with a reduced degree of endothelial injury. Our study opens a new, unexplored area of research on the protective features of peripheral monocytes in hypertension.