Nrf2?/? mice exhibit decreased NQO-1 mRNA and protein expression compared with WT mice during DSS-induced colitis, whereas HO-1 mRNA remained Pacritinib FLT3 unchanged, despite a significant decrease in HO-1 protein levels. Decreased HO-1 protein levels could be mediated by posttranslational modifications, leading to increased protein degradation (4). As shown previously (52), colonic mRNA expression of Nrf2 was increased in PHB Tg mice during DSS-induced colitis compared with WT mice; however, Nrf2 mRNA was undetectable in Nrf2?/? and PHB Tg/Nrf2?/? mice (Fig. 4A). Fig. 4. PHB Tg mice exhibit increased colonic HO-1 and NQO-1 expression during DSS colitis, which is unaffected by Nrf2 deletion. A: qRT-PCR analysis of HO-1, NQO-1, and Nrf2 in total RNA isolated from colon. Values are means �� SE (n = 8 per group).

* … PHB Tg mice are less susceptible to TNBS-induced colitis independently of Nrf2. TNBS-induced colitis was used as a second well-known model of intestinal inflammation. On day 1 after administration of TNBS, all mice lost the same amount of body weight (Fig. 5A). PHB Tg and PHB Tg/Nrf2?/? mice recovered the lost weight by day 3 after TNBS administration, while WT and Nrf2?/? mice did not. Consistent with this observation, WT and Nrf2?/?, but not PHB Tg and PHB Tg/Nrf2?/?, mice exhibited increased MPO activity in the distal colon following TNBS treatment compared with vehicle controls (Fig. 5B). Increased expression of HO-1 and NQO-1 mRNA (Fig. 5C) and protein (Fig. 5D) was sustained in PHB Tg/Nrf2?/? mice during TNBS-induced colitis. These results corroborate our findings with the DSS model of colitis.

Fig. 5. PHB Tg mice are less susceptible to 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis independently of Nrf2. A: percent change in body weight. B: neutrophil infiltration into the colon, quantified by MPO activity. C: qRT-PCR analysis of HO-1, … Colonic endogenous (mouse) and exogenous (human) PHB mRNA expression during DSS- and TNBS-induced colitis. To determine colonic endogenous PHB or transgene expression, mouse PHB and human PHB mRNA expression, respectively, were assessed across all the genotypes of mice by qRT-PCR after DSS (Fig. 6A) or TNBS (Fig. 6B) treatment. There was no significant effect of Nrf2 knockout on endogenous colonic PHB mRNA expression. The induction of colitis by DSS or TNBS decreased endogenous PHB mRNA expression. These data are in agreement with our previous findings showing a decrease in endogenous PHB protein levels during colitis (49). Colonic PHB transgene expression is significantly increased in PHB Tg and PHB Tg/Nrf2?/? Cilengitide mice at baseline and during colitis. Fig. 6. Colonic endogenous (mouse) and exogenous (human) PHB mRNA expression during DSS- and TNBS-induced colitis.