| First Author | Morampudi V | Year | 2015 |
| Journal | Am J Physiol Gastrointest Liver Physiol | Volume | 308 |
| Issue | 5 | Pages | G389-402 |
| PubMed ID | 25501546 | Mgi Jnum | J:223849 |
| Mgi Id | MGI:5660473 | Doi | 10.1152/ajpgi.00195.2014 |
| Citation | Morampudi V, et al. (2015) Vasoactive intestinal peptide prevents PKCepsilon-induced intestinal epithelial barrier disruption during EPEC infection. Am J Physiol Gastrointest Liver Physiol 308(5):G389-402 |
| abstractText | We previously showed that vasoactive intestinal peptide (VIP) protects against bacterial pathogen-induced epithelial barrier disruption and colitis, although the mechanisms remain poorly defined. The aim of the current study was to identify cellular pathways of VIP-mediated protection with use of pharmacological inhibitors during enteropathogenic Escherichia coli (EPEC) infection of Caco-2 cell monolayers and during Citrobacter rodentium-induced colitis. EPEC-induced epithelial barrier disruption involved the PKC pathway but was independent of functional cAMP, Rho, and NF-kappaB pathways. VIP mediated its protective effects by inhibiting EPEC-induced PKC activity and increasing expression of the junctional protein claudin-4. Short-term treatment with TPA, which is known to activate PKC, was inhibited by VIP pretreatment, while PKC degradation via long-term treatment with TPA mimicked the protective actions of VIP. Immunostaining for specific PKC isotypes showed upregulated expression of PKCtheta and PKCepsilon during EPEC infection. Treatment with specific inhibitors revealed a critical role for PKCepsilon in EPEC-induced barrier disruption. Furthermore, activation of PKCepsilon and loss of barrier integrity correlated with claudin-4 degradation. In contrast, inhibition of PKCepsilon by VIP pretreatment or the PKCepsilon inhibitor maintained membrane-bound claudin-4 levels, along with barrier function. Finally, in vivo treatment with the PKCepsilon inhibitor protected mice from C. rodentium-induced colitis. In conclusion, EPEC infection increases intracellular PKCepsilon levels, leading to decreased claudin-4 levels and compromising epithelial barrier integrity. VIP inhibits PKCepsilon activation, thereby attenuating EPEC-induced barrier disruption. |
