Inhibition of carbonic anhydrases enhance the recovery from acute experimental colitis by controlling epithelial regeneration

Abstract

Background & Aims: Colonic crypt elongation occurs during both chronic colitis and in the recovery phase of acute colitis. The impact of these alterations on epithelial cell function is not fully defined yet. Methods: DNA microarray analyses of colonic epithelial cells (CEC) of WT and TCRet KO mice were performed, and the results were confirmed by RT-PCR and immunohistocbemistry (IHC). The function of selected gene-encoding proteins was examined by administration of specific inhibitors directed toward products identified by expression analysis in WT mice given 4% DSS to induce colitis (DSS-mice). Results: DNA microarray analysis and RT-PCR revealed that expression of detoxification-associated genes, especially carbonic anhydrase (CAR)-IV and phenol sulfotransferase (PST)-I, was markedly downregufated in TCRc~ KO mice compared to WT mice. Of note, CAR-IV mRNA expression was markedly downregnlated in the CEC of TCRa KO mice compared to IL-10 KO mice, CD45RBhi cell transferred model and DSS-mice In contrast, PST-1 mRNA was significantly decreased in all the examined chronic colitis models but not the DSS-mice. IHC showed that CAR protein expressed in the surface epithelium rather than crypts in WT mice but not in TCR,~ KO mice. The intrarectal administration of valproic acid (inhibitor of CAR-I, II and IV) into WT mice significantly enhanced the recovery from DSS-induced acute colitis. In contrast, niflumic acid (inhibitor of PST-I) administration failed to suppress the DSScolitis. Histologically, markedly increased number Of BrdU + CEC after Day 6 was obseived in the DSS treated mice administrated with valproic acid compared to those with PBS. However the number of BrdU + CEC were markedly decreased and less number of mononuclear cell infiltration was found in lamina propria on Day 12 in valproic acid administrated mice. Conclusions: The expression of CAR-IV may significantly modulate the development of colitis; it was downregulated in CEC of Th2-mediated but not Th 1 and chemically induced colitis. The in vivo neutralization of CAR activity may provide a therapeutic strategy for active (acute) inflammation.