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From a physiological point of view, VEGFs (vascular endothelial growth factors) and their receptors (VEGFR) play a critical role in vascular development angiogenesis, endothelial function, and vascular tone. On the pathological side, VEGF–VEGFR signaling may induce dysregulated angiogenesis, which contributes to the growth and to the spread of tumors, being essential for neoplastic proliferation and invasion. Pharmacological inhibition of VEGF–VEGFR is now a cornerstone in the treatment of many malignancies; however, treatment with VEGF inhibitors is commonly associated with an increase in blood pressure values. This side effect is strictly connected with the mechanism of action of these medications and might represent an index of therapy efficacy. The optimal management of this form of hypertension is, at present, not clear. Calcium channel blockers and renin-angiotensin system inhibitors probably represent the most appropriate classes of hypertensive dugs for the treatment of this condition; however, no conclusive data are presently available.

Objective: It has been previously demonstrated that T lymphocytes may be involved in the development of hypertension and microvascular remodeling, and that circulating T effector lymphocytes may be increased in hypertension. In particular, Th1 and Th17 lymphocytes may contribute to the progression of hypertension and microvascular damage while TREG lymphocytes seem to be protective. However, no data is available about patients with severe obesity, in which pronounced microvascular alterations were observed. Methods: We have investigated 32 severely obese patients undergoing bariatric surgery, 24 normotensive lean subjects and 11 hypertensive lean subjects undergoing an election surgical intervention. No sign of local or systemic inflammation was present in any subject or patient. A peripheral blood sample was obtained before surgery for assessment of CD4+ T lymphocyte subpopulations. Lymphocyte phenotype was evaluated by flow cytometry after 5 hour in vitro activation in order to assess T-effector and T-regulatory (TREG) lymphocytes. Subsets of TREGS were defined as follows: −TREGS recent thymic emigrants (RTE), directly derived from thymus: CD31+; −TREGS naïve: CCR7+CD45RA+; −TREGS central memory (CM): CCR7+CD45RA−; −TREGS effector memory (EM): CCR7−CD45RA−; −TREGS terminal differentiated effector memory (TDEM): CCR7−CD45RA+. Results: The results are summarized in the Table (*p < 0.05, **p < 0.01, ***p < 0.001 vs. lean normotensives; #p < 0.05, ##p < 0.01, ###p < 0.001 vs. lean hypertensives). A marked reduction of several TREG subpopulations was observed in obese patients compared with controls, together with an increased in some T-effector cells. Lean normotensives Lean hypertensives Obese patients TREGs (%) 4.11 ± 1.60 4.64 ± 1.66 2.69 ± 1.81**## TREGs (abs number) 45.4 ± 24.3 45.4 ± 23.8 27.3 ± 21.1**# TREGs naíve (%) 22.1 ± 10.1 18.1 ± 13.1 13.34 ± 12.9** TREGs naíve (abs number) 10.6 ± 7.75 9.71 ± 8.87 3.87 ± 5.28***## TREG CM (%) 32.3 ± 13.8 32.8 ± 17.8 22.7 ± 15.2*# TREGs CM (abs number) 14.7 ± 10.2 14.2 ± 9.08 6.10 ± 8.08***## CD4+ EM (%) 24.4 ± 9.96 26.8 ± 12.5 34.1 ± 13.3** CD161+CD28+ (%) 86.2 ± 28.5 94.9 ± 5.63 97.2 ± 5.39* Conclusion: TREG lymphocytes are clearly reduced in severely obese patients, possibly contributing to the development of marked microvascular alterations previously observed in such a population.