Local injection of dsRNA targeting calcitonin receptor-like receptor (CLR) ameliorates Clostridium difficile toxin A-induced ileitis

• Type of Material: Article
• Authors: Aditi Bhargava, University of California San Francisco; Matthew Clifton, Emory University; Pallavi Mhsake, University of California San Francisco; Min Liao, University of California San Francisco; Charalabos Pothoulakis, University of California Los Angeles; Susan E. Leeman, Boston University; Eileen F. Grady, University of California San Francisco
• Language: English
• Date: 2013-01-08
• Publisher: National Academy of Sciences
• Publication Version: Final Published Version
• Copyright Statement: Copyright Bhargava et al.
• Final Published Version (URL): http://dx.doi.org/10.1073/pnas.1219733110
• Title of Journal or Parent Work: Proceedings of the National Academy of Sciences
• ISSN: 0027-8424
• Volume: 110
• Issue: 2
• Start Page: 731
• End Page: 736
• Grant/Funding Information: This project was supported by DK52387 (to E.F.G.), CCFA1730 (to E.F.G.), DK080787 (to A.B.), DK080787-S2 (to A.B.), and DK47343 (to C.P.).; M.S.C. was supported by National Institutes of Health Training Grant T32 DK07573.
• Keywords: RAT; EXPRESSION; ACTIVITY-MODIFYING PROTEIN-1; INTESTINAL INFLAMMATION; Science & Technology - Other Topics; INFECTION; CGRP; RNAi; nuclear translocation; DORSAL-ROOT GANGLIA; MULTIDISCIPLINARY SCIENCES; GENE-RELATED PEPTIDE; Science & Technology; LOCALIZATION; ENTERITIS; Multidisciplinary Sciences
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, Pharmacology

Abstract

Enteritis caused by Clostridium difficile toxin (Tx) is a nosocomial disease of increasing clinical concern, but the local mediators of C. difficile TxA inflammation are unknown. The potent vasodilator calcitonin gene-related peptide mediates neurogenic inflammation via the calcitonin receptor-like receptor (CLR). Here we examined the ileum-specific effects of reducing CLR on TxA ileitis by local preinjection of double-stranded RNAs. Treatment with CLR dsRNA for 7 d decreased CLR immunoreactivity, whereas treatment with non-CLR dsRNA did not. Subsequent injection of TxA in the same location increased CLR in rats treated with non-CLR dsRNA but not in rats treated with CLR dsRNA, documenting that local injection of dsRNA is effective in preventing the increase in CLR immunoreactivity in response to local TxA. After non-CLR dsRNA pretreatment, TxA induced robust intestinal secretion, myeloperoxidase activity, and histopathologic indications of inflammation including epithelial damage, congestion, neutrophil infiltration, loss of mucin from goblet cells, and increase in mast cell numbers. After CLR dsRNA pretreatment, TxA-induced changes in intestinal secretion and histopathologic inflammation were improved, including normal mucin staining and fewer resident mast cells. Loss of CLR prevented TxA-mediated activation of NF-κB and concomitant increases in pERK1/2 and TNF-α mRNA. Locally produced CLR plays a proinflammatory role in TxA ileitis via MAPK signaling and TNF-α. The results reported here strongly suggest that a local injection of dsRNA targeting CLR could be an effective local therapeutic approach at the inflammation site in the treatment of a growing, clinically relevant hospital-acquired disease, C. difficile infection.