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

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.

• Authors: Aditi Bhargava, Matthew S Clifton, Pallavi Mhaske, Pallavi Mhsake, Min Liao, Charalabos Pothoulakis, Susan E Leeman, Eileen F Grady
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 110 Issue 2 Pg. 731-6 (Jan 08 2013) ISSN: 1091-6490 [Electronic] United States
• PMID: 23267070 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Bacterial Toxins
• Calcitonin Receptor-Like Protein
• Enterotoxins
• Mucins
• NF-kappa B
• RNA, Double-Stranded
• Tumor Necrosis Factor-alpha
• tcdA protein, Clostridium difficile
• Peroxidase
• Mitogen-Activated Protein Kinases

Topics

• Animals
• Bacterial Toxins (toxicity)
• Blotting, Western
• Calcitonin Receptor-Like Protein (administration & dosage, immunology, metabolism)
• Enterotoxins (toxicity)
• Goblet Cells (drug effects)
• Ileitis (chemically induced, drug therapy)
• Male
• Mast Cells (drug effects)
• Microscopy, Fluorescence
• Mitogen-Activated Protein Kinases (metabolism)
• Mucins (metabolism)
• NF-kappa B (metabolism)
• Neutrophil Infiltration (drug effects)
• Peroxidase (metabolism)
• RNA Interference
• RNA, Double-Stranded (administration & dosage, metabolism, pharmacology)
• Rats
• Rats, Sprague-Dawley
• Signal Transduction (drug effects)
• Statistics, Nonparametric
• Tumor Necrosis Factor-alpha (metabolism)