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Journal of Clinical Gastroenterology:
doi: 10.1097/MCG.0b013e318265ea7d

Microbiota, Innate Immune System, and Gastrointestinal Muscle: Ongoing Studies

Tattoli, Ivan PhD; Petitta, Chiara BS; Scirocco, Annunziata PhD; Ammoscato, Francesca BS; Cicenia, Alessia BS; Severi, Carola PhD, MD

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Aim: To test the activities of culture-extracted or commercially available toll-like receptors (TLRs) ligands to establish their direct impact on target gastrointestinal motor cells.

Methods: Short-term and long-term effects of Shigella flexneri M90T and Escherichia coli K-2 strains-extracted lipopolysaccharides (LPS), commercially highly purified LPS (E. coli O111:B4 and EH100), and Pam2CSK4 and Pam3CSK4, which bind TLR2/6 and TLR1/2 heterodimers, respectively, have been assessed on pure primary cultures of colonic human smooth muscle cells (HSMC).

Results: Pathogenic Shigella-LPS and nonpathogenic E. coli K-2-LPS induced a time-dependent decrease of resting cell length and acetylcholine-induced contraction, with both alterations occurring rapidly and being more pronounced in response to the former. However, their effects differed, prolonging HSMC exposure with Shigella-LPS effects maintained throughout the 4 hours of observation compared with E. coli K-2-LPS, which disappeared after 60 minutes of incubation. Similar differences in magnitude and time dependency of myogenic effects were observed between pure TLR4 and TLR2/1 or TLR2/6 ligands. The specific activation of TLR4 with LPS from pathogen or nonpathogen E. coli, O111:B4 and EH100, respectively, induced smooth muscle alterations that progressively increased, prolonging incubation, whereas TLR2 ligands induced short-term alterations, of a lesser magnitude, which decreased over time. The real-time polymerase chain reaction analysis showed that HSMC express mRNA for TLR1, 2, 4, and 6, substantiating a direct effect of TLR ligands on human colonic smooth muscle.

Conclusions: This study highlights that bacterial products can directly affect gastrointestinal motility and that TLRs subtypes may differ in their cellular activity.

© 2012 Lippincott Williams & Wilkins, Inc.


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