Campylobacter concisus pathotypes induce distinct global responses in intestinal epithelial cells.

Nandan P Deshpande,Hazel M Mitchell,Nadeem O Kaakoush,Nidhi Sodhi,Marc R Wilkins,Natalia Castaño-Rodríguez,Emily Bainbridge,Stephen M Riordan

doi:10.1038/srep34288

Nandan P Deshpande, Hazel M Mitchell + Show 6 more

Open Access

https://doi.org/10.1038/srep34288

Copy DOI

Journal: Scientific Reports	Publication Date: Sep 1, 2016
Citations: 24	License type: CC BY 4.0

Affiliation: UNSW Sydney, Prince of Wales Hospital

Abstract

The epithelial response to the opportunistic pathogen Campylobacter concisus is poorly characterised. Here, we assessed the intestinal epithelial responses to two C. concisus strains with different virulence characteristics in Caco-2 cells using RNAseq, and validated a subset of the response using qPCR arrays. C. concisus strains induced distinct response patterns from intestinal epithelial cells, with the toxigenic strain inducing a significantly more amplified response. A range of cellular functions were significantly regulated in a strain-specific manner, including epithelial-to-mesenchymal transition (NOTCH and Hedgehog), cytoskeletal remodeling, tight junctions, inflammatory responses and autophagy. Pattern recognition receptors were regulated, including TLR3 and IFI16, suggesting that nucleic acid sensing was important for epithelial recognition of C. concisus. C. concisus zonula occludens toxin (ZOT) was expressed and purified, and the epithelial response to the toxin was analysed using RNAseq. ZOT upregulated PAR2 expression, as well as processes related to tight junctions and cytoskeletal remodeling. C. concisus ZOT also induced upregulation of TLR3, pro-inflammatory cytokines IL6, IL8 and chemokine CXCL16, as well as the executioner caspase CASP7. Here, we characterise distinct global epithelial responses to C. concisus strains, and the virulence factor ZOT, and provide novel information on mechanisms by which this bacterium may affect the host.

Highlights

The response of Caco-2 intestinal epithelial cells (IECs) to two C. concisus strains with different virulence mechanisms was examined using RNA-seq
When the threshold was increased (Q < 0.1), the number of transcripts only increased to 156 (Supplementary Data 1). This epithelial response was weak when compared to the response of THP-1 derived macrophages[19], which differentially expressed 8,343 transcripts at greater than 1.5-fold regulation (Q < 0.05) following infection with C. concisus UNSWCD
A range of virulence mechanisms and factors have been identified in C. concisus strains[13,18], which has led to the division of strains into at least two pathotypes, adherent-invasive (AICC) and adherent-toxigenic (AToCC) strains[12]

Summary

Introduction

Ninety-eight transcripts were found to be differentially expressed (Q < 0.05) following infection of IECs with the AICC strain UNSWCD (Fig. 1A, Supplementary Data 1). Transcripts involved in the inflammatory response were differentially expressed (upregulated) following infection with C. concisus UNSWCD. The differential expression of genes involved in autophagy was identified in IECs infected with C. concisus BAA-1457 (Supplementary Data 1).

Results

Conclusion