Introduction: Campylobacter jejuni is a Gram-negative spiral-shaped bacterium that is the most prevalent cause of bacterial diarrhea in humans and that might be responsible for 500 million cases of gastroenteritis world over each year. An important C. jejuni virulence factor is the Cytolethal Distending Toxin (CDT) that is thought to be associated with C. jejuni-induced local acute inflammation involved in enterocolitis. Our research evaluates the sequence of lethal and sub-lethal events in CaCo-2 cells, as a model of intestinal epithelium, exposed to lysates of three distinct strains, C. jejuni ATCC 33291 and C. jejuni ISS 1, compared to C. jejuni 11168H cdtA mutant. Methods: Cell lysates of C. jejuni ATCC 33291, C. jejuni ISS 1 and C. jejuni 11168H cdtA mutant strains were added to CaCo-2 cell monolayers and, after 24, 48 and 72 hours, cells were analysed by means of flow cytometry and confocal microscopy, to detect DNA content, death features, mitochondrial-lysosomal network and autophagic pathway. Results: C. jejuni lysates induced cell cycle arrest in G2/M phase, as highlighted by propidium iodide staining, and induction of apoptosis, revealed by 7-AAD. The C. jejuni ISS 1 wild-type strain mainly induced lysosomal alterations and the most relevant mitochondrial modifications. Instead, the C. jejuni ATCC 33291 strain causes changes in autophagic pathway as indicated by the results from monodansylcadaverine (MDC) staining, a specific autophagolysosomal marker, suggesting that CaCo-2 cells respond to stimuli by activating the autophagic machinery, largely involved in bacterial infections. Conclusions: Our results suggest that C. jejuni lysates-treated CaCo-2 cells displayed different features, depending on the particular strain. In fact, lysates are able to induce lethal and sub-lethal effects differently targeting mitochondrial, lysosomal and autophagosomal compartments. These data are linked to the potentially complex interactions that underlay the etiopathogenesis of enteric infections.

Lethal and sub-lethal effects induced by Campylobacter jejuni lysates on CaCo-2 cells

Mariele Montanari;Erica Cesarini;Raffaella Campana;Federica Sola;Maria Gemma Nasoni;Francesca Luchetti;Wally Baffone;Stefano Papa;Barbara Canonico
2019

Abstract

Introduction: Campylobacter jejuni is a Gram-negative spiral-shaped bacterium that is the most prevalent cause of bacterial diarrhea in humans and that might be responsible for 500 million cases of gastroenteritis world over each year. An important C. jejuni virulence factor is the Cytolethal Distending Toxin (CDT) that is thought to be associated with C. jejuni-induced local acute inflammation involved in enterocolitis. Our research evaluates the sequence of lethal and sub-lethal events in CaCo-2 cells, as a model of intestinal epithelium, exposed to lysates of three distinct strains, C. jejuni ATCC 33291 and C. jejuni ISS 1, compared to C. jejuni 11168H cdtA mutant. Methods: Cell lysates of C. jejuni ATCC 33291, C. jejuni ISS 1 and C. jejuni 11168H cdtA mutant strains were added to CaCo-2 cell monolayers and, after 24, 48 and 72 hours, cells were analysed by means of flow cytometry and confocal microscopy, to detect DNA content, death features, mitochondrial-lysosomal network and autophagic pathway. Results: C. jejuni lysates induced cell cycle arrest in G2/M phase, as highlighted by propidium iodide staining, and induction of apoptosis, revealed by 7-AAD. The C. jejuni ISS 1 wild-type strain mainly induced lysosomal alterations and the most relevant mitochondrial modifications. Instead, the C. jejuni ATCC 33291 strain causes changes in autophagic pathway as indicated by the results from monodansylcadaverine (MDC) staining, a specific autophagolysosomal marker, suggesting that CaCo-2 cells respond to stimuli by activating the autophagic machinery, largely involved in bacterial infections. Conclusions: Our results suggest that C. jejuni lysates-treated CaCo-2 cells displayed different features, depending on the particular strain. In fact, lysates are able to induce lethal and sub-lethal effects differently targeting mitochondrial, lysosomal and autophagosomal compartments. These data are linked to the potentially complex interactions that underlay the etiopathogenesis of enteric infections.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11576/2755431
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