Effect of the ENV59-GP3 peptide and KCa3.1-blocker NS6180 in DSS-induced acute colitis mice model
The effect of blocking KCa3.1 on the immune responsein vivo was evaluated using DSS-induced acute colitis model. Starting at day 0 and throughout the course of the experiment, the mice were dosed i.p. twice weekly with a ENV59-GP3 peptide, at 0.5 mg per kg of body weight; selective KCa3.1 blocker NS6180 at 2.5 mg per kg of body weight, or with saline (control). The development of IBD was monitored as daily average weight loss development. As shown in Figure 1A, DSS administration resulted in significant weight loss (control), whereas in mice treated with ENV59-GP3 peptide or the channel blocker NS6180, weight loss was significantly reduced by day 6~10. Furthermore, we found that colon length, a macroscopic indicator of colitis severity, in DSS-treated mice control group was significantly reduced. In contrast, administration of ENV59-GP3 at 0.5 mg/kg or NS6180 at 2.5 mg/kg led to a marked improvement in colon length (p <0.0001) (Figure 1B). Additionally, we tested whether treatments with ENV59-GP3 peptide or NS6180 blocker would have an impact on expression of proinflammatory cytokines in colon tissues, presumably as an effect of upstream blockage of the KCa3.1 channel. Consistent with less severe disease, TNF-α, IL-1β and IL-6 (Figure 1C) show decreased expression in ENV59-GP3 and NS6180 treated animals, though only difference in IL-6 expression was statistically significant. Unfortunately, such a high degree of variability in RT-qPCR analyses of inflammatory mediators are often observed in similar in vivo models. Furthermore, the expression of IL-17 mRNA was not markedly reduced by either tested treatments. At the time of sacrifice, ENV59-GP3 and/or NS6180 treated mice displayed significantly reduced colonic shortening and decreased intestinal inflammation compared with control group (Figure 2).