RELATIONSHIP BETWEEN MICROVASCULAR STRUCTURE AND T REGULATORY LYMPHOCYTES OF SMALL RESISTANCE ARTERIES

Objective: Recently it has been demonstrated a role for adaptive immunity, particularly
for T regulatory lymphocytes (Tregs), in the development of hypertension
and in preventing of angiotensin II–induced vascular injury and infl ammation
in animal models (Barhoumi T et al, Hypertension 2011;57:469–476). However,
no data are presently available in human beings about possible relationships between
Tregs and microvascular structural alterations.
Design and method: In the present study we enrolled 11 normotensive subjects
and 8 hypertensive patients undergoing an election surgical intervention. All patients
underwent a biopsy of subcutaneous fat during surgery. Subcutaneous small
resistance artery structure was assessed by wire myography and media to lumen
ratio (M/L) was calculated. W/L of retinal arterioles was obtained by Scanning
Laser Doppler Flowmetry. Functional (basal) and structural (total) microvascular
density were studied by capillaroscopy before and after venous congestion. No
sign of local or systemic infl ammation was present in any subjects or patients. We
extracted genomic DNA from small resistance arteries and analyzed methylation
status of the FoxP3 gene promoter involved in Treg lymphocytes activation. Unmethylated
FoxP3 has been demonstrated to be specifi c for Treg lymphocytes. A
peripheral blood sample was obtained before surgery for routine chemistry
Results: A significant positive correlation was detected between Tregs in small resistance
arteries and basal, total and delta gain capillary density in the forearm, whereas no
correlations were observed with small resistance artery M/L and retinal arteriole
W/L. In addition, a signifi cant inverse correlation was detected between Treg in
subcutaneous small vessels and C reactive protein.
Conclusions: Our data suggest that Treg lymphocytes detected in subcutaneous
small resistance artery wall are related with capillary density and inversely related
with infl ammatory markers suggesting a protecting role of Treg also, probably, in
terms of angiogenetic properties.