Abstract
Background
Immune cells are key regulators of the vascular inflammatory response characteristic of hypertension. In hypertensive rodents, regulatory T lymphocytes (Treg,
CD
4
+
CD
25
+
) prevented vascular injury, cardiac damage, and endothelial dysfunction of mesenteric arteries. Whether Treg modulate the cerebrovascular damage induced by hypertension is unknown.
Methods and Results
C57
BL
/6 mice were perfused with angiotensin
II
(Ang
II
; 1000 ng/kg per minute) for 14 days and adoptive transfer of 3×10
5
CD
4
+
CD
25
+
T cells was performed via 2 intravenous injections. Control mice received a sham surgery and
PBS
. Treg prevented Ang
II
‐induced neurovascular uncoupling (
P
<0.05) and endothelial impairment (
P
<0.05), evaluated by laser Doppler flowmetry in the somatosensory cortex. The neuroprotective effect of Treg was abolished when they were isolated from mice deficient in interleukin‐10. Administration of interleukin‐10 (60 ng/d) to hypertensive mice prevented Ang
II
‐induced neurovascular uncoupling (
P
<0.05). Treg adoptive transfer also diminished systemic inflammation induced by Ang
II
(
P
<0.05), examined with a peripheral blood cytokine array. Mice receiving Ang II + Treg exhibited reduced numbers of Iba‐1+ cells in the brain cortex (
P
<0.05) and hippocampus (
P
<0.001) compared with mice infused only with Ang II. Treg prevented the increase in cerebral superoxide radicals. Overall, these effects did not appear to be directly modulated by Treg accumulating in the brain parenchyma, because only a nonsignificant number of Treg were detected in brain. Instead, Treg penetrated peripheral tissues such as the kidney, inguinal lymph nodes, and the spleen.
Conclusions
Treg prevent impaired cerebrovascular responses in Ang
II
‐induced hypertension. The neuroprotective effects of Treg involve the modulation of inflammation in the brain and periphery.