MAPK Activation Is Essential for Waddlia chondrophila Induced CXCL8 Expression in Human Epithelial Cells.

Skye Storrie,Nick Wheelhouse,David Longbottom,Peter G Barlow

doi:10.1371/journal.pone.0152193

Skye Storrie, Nick Wheelhouse + Show 2 more

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https://doi.org/10.1371/journal.pone.0152193

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Journal: PloS one	Publication Date: Mar 22, 2016
Citations: 2	License type: CC BY 4.0

Affiliation: Moredun Research Institute, Edinburgh Napier University

Abstract

BackgroundWaddlia chondrophila (W. chondrophila) is an emerging agent of respiratory and reproductive disease in humans and cattle. The organism is a member of the order Chlamydiales, and shares many similarities at the genome level and in growth studies with other well-characterised zoonotic chlamydial agents, such as Chlamydia abortus (C. abortus). The current study investigated the growth characteristics and innate immune responses of human and ruminant epithelial cells in response to infection with W. chondrophila.MethodsHuman epithelial cells (HEp2) were infected with W. chondrophila for 24h. CXCL8 release was significantly elevated in each of the cell lines by active-infection with live W. chondrophila, but not by exposure to UV-killed organisms. Inhibition of either p38 or p42/44 MAPK significantly inhibited the stimulation of CXCL8 release in each of the cell lines. To determine the pattern recognition receptor through which CXCL8 release was stimulated, wild-type HEK293 cells which express no TLR2, TLR4, NOD2 and only negligible NOD1 were infected with live organisms. A significant increase in CXCL8 was observed.Conclusions/SignificanceW. chondrophila actively infects and replicates within both human and ruminant epithelial cells stimulating CXCL8 release. Release of CXCL8 is significantly inhibited by inhibition of either p38 or p42/44 MAPK indicating a role for this pathway in the innate immune response to W. chondrophila infection. W. chondrophila stimulation of CXCL8 secretion in HEK293 cells indicates that TLR2, TLR4, NOD2 and NOD1 receptors are not essential to the innate immune response to infection.

Highlights

Waddlia chondrophila (W. chondrophila) is an emerging agent of respiratory and reproductive disease in humans and cattle
Consistent with the hypothesis that active replication of the bacteria is an essential requirement for CXCL8 release, chloramphenicol treatment led to a significant reduction in CXCL8 production in W.chondrophila infected HEp2 cells (1365 ± 171 pg/ml control vs 35 ± 18 pg/ml chloramphenicol treated; p
The results from the current study clearly demonstrate that W. chondrophila infection leads to an increase in CXCL8 release from human epithelial cells, which is consistent with its role as an emerging human pathogen

Summary

Introduction

Waddlia chondrophila (W. chondrophila) is an emerging agent of respiratory and reproductive disease in humans and cattle. A number of human studies have indicated potential pathogenic roles in both reproductive [3,4] and respiratory conditions [5] suggesting that the organism can infect and replicate at multiple mucosal sites throughout the host. Comparative studies have demonstrated distinct differences in the membrane structure [8] and the developmental cycle [9] of W. chondrophila compared to other pathogenic chlamydial species, which have been suggested to reduce the pathogenicity of the organism Despite these observed differences, infection of ovine trophoblast cells with W. chondrophila leads to a pro-inflammatory response [10] similar to that observed with the pathogen C. abortus [11] suggesting stimulation of similar signalling pathways within the host cell. The current study investigated the growth characteristics and innate immune responses of human and ruminant epithelial cells in response to infection with W. chondrophila

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Conclusion