Brucella suis vaccine strain S2-infected immortalized caprine endometrial epithelial cell lines induce non-apoptotic ER-stress

Cell Stress and Chaperones (2015) 20:399409

DOI 10.1007/s12192-014-0564-x

ORIGINAL PAPER

Brucella suis vaccine strain S2-infected immortalized caprine endometrial epithelial cell lines induce non-apoptotic ER-stress

Xiangguo Wang & Pengfei Lin & Yanlong Yin &

Jinhua Zhou & Lanjie Lei & Xudong Zhou & Yaping Jin &

Aihua Wang

Received: 11 September 2014 /Revised: 23 November 2014 /Accepted: 16 December 2014 /Published online: 30 January 2015 # Cell Stress Society International 2015

Abstract Brucella, which is regarded as an intracellular pathogen responsible for a zoonotic disease called brucellosis, survives and proliferates within several types of phagocytic and non-phagocytic cells. Brucella infects not only their preferred hosts but also other domestic and wild animal species, inducing abortion and infertility. Therefore, the interaction between uterine cells and Brucella is important for understanding the pathogenesis of this disease. In this study, we describe the Brucella suis vaccine strain S2 (B.suis.S2) infection and replication in the immortalized caprine endometrial epithelial cell line hTERT-EECs and the induced cellular and molecular response modulation in vitro. We found that B.suis S2 was able to infect and replicate to high titers and inhibit the proliferation of EECs and induce non-apoptotic pathways, as determined by B.suis.S2 detection using MTT and acridine orange/ethidium bromide (AO/EB) staining and flow cytometry. We explored the evidence of non-apoptotic pathways using real-time quantitative RT-PCR and by western blot analysis. Finally, we discovered the over-expression of GRP78, ATF4, ATF6, PERK, eIF2, CHOP, and cytochrome c (Cyt-c) but not IRE1, xbp-1, and caspase-3 in B.suis.S2 (HK)-attacked and B.suis.S2-infected cells, suggesting that the molecular mechanism of ER stress sensor activation by

B.suis.S2 is basically concomitant with that by B.suis.S2 (HK) and that ER stress, especially the PERK pathway, plays an important role in the process of B.suis.S2 infecting EEC, which may, in part, explain the role of the uterus in the pathogenesis of B.suis.S2.

Keywords B.suis.S2 . Caprine endometrial epithelial cell . Endoplasmic reticulum stress . Apoptosis . Infection

AbbreviationsT4SS Type IV secretion systemER Endoplasmic reticulumEEC Caprine endometrial epithelial cellB.suis.S2 Brucella suis vaccine strain S2PERK Protein kinase RNA-like kinaseIRE1 Inositol-requiring enzyme 1

ATF6 Activating transcription factor 6GRP78 78-kDa glucose-regulated proteinCHOP C/EBP homologus proteinCFU Colony-forming unitsTm Tunicamycinxbp-1 X-box binding protein 1MTT-3-[4 5-Dimethylthiazol-2-yl]-25 Diphenyltetrazolium bromide assay eIF2 Subunit of eukaryotic initiation factor 2

Introduction

Bacteria of...