Induction of pro-inflammatory programs in enteroendocrine cells by the Toll-like receptor agonists flagellin and bacterial LPS.
Enteroendocrine cells are hormone-secreting cells spread along the intestinal epithelium. Their principal function is to promote the digestion of food. However, little is known about other functions that these cells may play, since they are difficult to study as a whole endocrine organ due to their diffuse localization. It is known that the intestinal epithelial barrier is actively involved in the host defense against pathogen invasion. Here we applied gene expression profiling to characterize the response of the human LCC-18 enteroendocrine cell line to physiological and pathological stimuli mimicked by fatty acids (FAs), flagellin and LPS exposure. We observed that these cells participate in an innate immune reaction to pathogens through the expression of pro-inflammatory factors (i.e. CXCL1 and 3 and IL-32) that we could validate by molecular and proteomic approach. Interestingly, IL-32 has been recently found over-expressed in the inflamed mucosa of patients affected by inflammatory bowel disease. This is very important because modifications of enteroendocrine cells during intestinal inflammation have been so far considered as secondary effects of the inflammatory status rather than due to direct pathogen/enteroendocrine cell interaction. As expected, FAs exposure up-regulates pro-differentiative genes and the production of cholecystokinin but it does not enhance the expression of pro-inflammatory genes. The present observations enlighten a new aspect of the cross talk between immune and endocrine system and suggest enteroendocrine cells as important contributors of inflammatory processes occurring in the gut in response to pathogen exposure and direct enhancers of the inflammatory status associated with human inflammatory bowel disease.
Mucosal Immunity Laboratory, Department of Human Morphology, Università degli Studi di Milano, via Mangiagalli 31, 20133 Milano, Italy.
Silvia
S
Selleri
Marco
M
Palazzo
Sara
S
Deola
Ena
E
Wang
Andrea
A
Balsari
Francesco M
FM
Marincola
Cristiano
C
Rumio
D045744:Cell Line, Tumor; D054360:Chemokine CXCL1 / Q000378:metabolism; D002766:Cholecystokinin / Q000378:metabolism; D019858:Enteroendocrine Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D004926:Escherichia coli; D005227:Fatty Acids / Q000378:metabolism; D005408:Flagellin / Q000494:pharmacology*; D020869:Gene Expression Profiling; D006801:Humans; D018928:Immunity, Mucosal / Q000187:drug effects; D015212:Inflammatory Bowel Diseases / Q000276:immunology / Q000378:metabolism; D007378:Interleukins / Q000378:metabolism; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D015213:Neuroimmunomodulation; D051193:Toll-Like Receptors / Q000819:agonists / Q000378:metabolism*
D054360:Chemokine CXCL1; D005227:Fatty Acids; C496971:IL32 protein, human; D007378:Interleukins; D008070:Lipopolysaccharides; D051193:Toll-Like Receptors; D005408:Flagellin; D002766:Cholecystokinin