Heme oxygenase-inhibition attenuates Lactobacillus induced foxp3 expression in mesenteric lymph nodes but does not interfere with down-regulation of T cell inflammatory cytokine release.

Balb/c mice received i.p. Chromium mesoporpyrin (CrMP) daily for 7 days. Mice were gavaged with JB-1 or vehicle for the last 5 days of experiment and mesenteric lymph nodes were harvested. (A) Single cell suspensions of mesenteric lymph nodes stained for CD4, CD25 and Foxp3 and analyzed by FACS. (B) Isolated mesenteric CD11c+ DC were co-cultured with L. rhamnosus JB-1 at a ratio of 10∶1/bacteria:DC, for 2 h at 37°C and incubated in the presence or absence of CrMP (5 µM) with purified CD4+ T cells from DO11.10 transgenic mice for 5 days stained for CD4, CD25 and Foxp3 and analyzed by FACS. (C&D) Single cell suspensions of mesenteric lymph nodes were stimulated by antibodies against CD3/CD28 for 48 hr and the supernatants analyzed for cytokine production. Release of TNF and IFNγ, relative to vehicle control (TNF 398±49.2 pg/ml, IFNγ 592±105 pg/ml) is depicted. Data is presented as mean values ± SEM n = 5, *p<0.05 compared to control values.