Human visceral adipose tissue contains resident regulatory T cells displaying activated-memory phenotype

PANDOLFI J; FERRARO A; BAZ P; PODHORZER, A; BILLORDO A; FAINBOIM L; ARRUVITO L

Congreso; LXI Reunión Científica Anual de la SAI.; 2013

# Background: Prolonged nutrient overload results in a state of chronic, low-grade inflammation in adipose tissue mainly localized in visceral adipose tissue (VAT) which promotes obesity-induced insulin resistance (IR). These findings raise the question of how fat inflammation can escape the regulatory immune response. CD4+ regulatory T cells have been described as one of the anti-inflammatory players in VAT (VATregs).      # Aim: To identify human VATregs, in both lean and obese subjects, which may contribute to understand the mechanism involve in IR.   # Results: Samples of peripheral blood and VAT were obtained from the greater omentum during endoscopic repair of hernias and during the performance of bariatric surgeries from lean or obese patients, respectively. We examined peripheral blood and VATregs by Flow Cytometry. Our data demonstrated that CD4+CD25+FOXP3+ VATregs mainly consist of differentiated CD45RA-CCR7-CD62L- effector-memory cells, whereas unprimed CD45RA+CCR7+CD62L+  naïve cells are almost absent, in both kind of donors. Functionally, VATregs expressed higher levels of CD39/ENTPD1 compared with those from peripheral blood and were granzyme-perforine positive. Finally, in comparison with lean donors, the frequency of VATregs in obese patients has been found to be lower.   # Conclusion: Human VATregs display an activated-memory phenotype in both obese and lean donor. Moreover, a diminished frequency of VATregs in obese patients could explain the growing setting of a low- grade inflammation in VAT. These observations suggest that a prolonged nutrient overload could be associated with a decrease regulatory function in this tissue. Finally, VATregs modulation could have a therapeutic potential for treating VAT inflammation.