- 作者：T. Lang ; C. Hudemann ; S. Bhushan ; S. Tchatalbachev ; H. Renz ; A. Meinhardt
- 刊名：Cytokine
- 出版年：2012
- 出版时间：September, 2012
- 年：2012
- 卷：59
- 期：3
- 页码：528
- 全文大小：44 K
class=""h4"">Introduction
Infection and inflammation of the urinary tract are aetiological factors contributing to 10-15 % of infertility cases in men. Epididymitis is often the consequence of ascending bacterial infection into the urinary tract. Specific strains of Uropathogenic E. coli (UPEC) produce the toxin alpha-haemolysin (hlyA), which has been shown to manipulate host immune responses by degrading components of the NF-¦ÊB signalling cascade following infection of bladder epithelial cells. The aim of this study was to elucidate the consequences of hlyA production on innate immune responses in the UPEC induced murine experimental epididymitis model.class=""h4"">Methods
To evaluate the consequences of hlyA on cytokine production in vitro, RAW 267.4 cells or single epididymides dissected from C57BL/6 N mice were left untreated, treated with LPS (100 ng/mL) or infected with the clinically relevant pyelonephritic?-haemolytic (UPEC CFT073) or non-haemolytic E. coli strain NPEC 470. Cell supernatants were collected following treatment and cytokine production analysed using the BD? Cytometric Bead Array. The establishment of the murine experimental epididymitis model was achieved through injection of 40,000 UPEC CFT073 or NPEC 470 in total, into both left and right vas deferens of C57BL/6 N mice. PBS injections were used as a sham control for in vivo experiments. Following 3 days infection, epididymides were dissected and snap frozen. qPCR analyses was performed to quantify pro-inflammatory gene expression. Immuno-fluorescent staining was used for the detection of macrophages (F4/80) and T-cells (CD3). Statistical analysis was performed by One-way ANOVA followed by the Bonferroni¡¯s Multiple Comparison Test where appropriate. P ? 0.05 is considered statistically significant.
class=""h4"">Results
In this study we show that the?-haemolytic UPEC strain CFT073 significantly reduced secretion of pro-inflammatory cytokines TNF-?, IL-6, IL-1 and IFN-? in epididymal organ cultures and RAW 267.4 cells following infection. Conversely, in vivo qPCR analyses revealed expression of early response genes TNF-? and IL-6 were significantly increased by day 3 following UPEC CFT073 infection. Interestingly, RANTES/CCL5 and IFN-? gene expression were differentially modulated dependent on the hylA status of the E. coli strain. Our findings illustrate that hlyA production significantly enhances RANTES expression following UPEC CFT073 infection in contrast to PBS and NPEC 470 infected mice. Conversely, IFN-? gene expression in UPEC CFT073 infected mice was comparable to PBS infected mice, whereas NPEC 470 significantly increased IFN-? expression. In addition, a decrease in the number of F4/80 and CD3+ cells within the epididymal interstitium of UPEC CFT073 infected mice was observed in comparison to NPEC 470 infected mice.
class=""h4"">Conclusion
Overall these finding suggest that hlyA produced by UPEC attenuates host innate immune responses in the initial phases of infection for successful colonisation within the epididymis. Furthermore, the down-regulation of IFN-? attenuates maturation of adaptive immune responses thereby evading elimination and contributing to persistence.