Alterations in deoxyribonucleic acid (DNA) methylation patterns of Calca, Timp3, Mmp2, and Igf2r are associated with chronic cystitis in a cyclophosphamide-induced mouse model

Objective: To determine whether epigenetic changes occur during cyclophosphamide-induced chronic bladder inflammation in mice. Materials and Methods: Epigenetic changes play a role in the regulation of inflammatory genes in noncancer diseases such as asthma and chronic obstructive pulmonary disease. However, epigenetic (deoxyribonucleic acid [DNA] methylation) changes during chronic bladder inflammation have not been previously described. Chronic cystitis was induced in 3 groups of adult CD-1 male mice using multiple weight-based intraperitoneal cyclophosphamide injections during a 3-month period. Histopathologic and MethyLight assays were performed on specimens with chronic bladder inflammation at multiple points to monitor cystitis progression and DNA methylation changes compared with the control specimens. Results: Histopathologic analysis showed the most extensive edema and urothelial sloughing at the 1-month point. MethyLight analyses revealed statistically significant changes in DNA methylation associated with the Calca, Timp3, Mmp2, and Igf2r genes in the chronic bladder injury model. The changes in DNA methylation associated with chronic cystitis were DNA hypomethylation of the Calca gene in the control tissue and DNA hypermethylation for the Calca, Timp3, Mmp2, and Igf2r genes compared with that in the control tissue. Conclusion: DNA methylation changes were noted in the Calca, Timp3, Mmp2, and Igf2r genes during chronic cystitis in a murine model. Epigenetic changes appear to play a role in the regulation of inflammatory bladder genes during chronic cystitis; however, additional studies are needed to elucidate the pathways associated with these genes.