Modified Profile of Matrix Metalloproteinase 2 and 9 Production by Human Fallopian Tube Epithelial Cells After Infection In Vitro With Neisseria gonorrhoeae

IL-17C is a driver of damaging inflammation during Neisseria gonorrhoeae infection of human Fallopian tube

The human pathogen Neisseria gonorrhoeae ascends into the upper female reproductive tract to cause damaging inflammation within the Fallopian tubes and pelvic inflammatory disease (PID), increasing the risk of infertility and ectopic pregnancy. The loss of ciliated cells from the epithelium is thought to be both a consequence of inflammation and a cause of adverse sequelae. However, the links between infection, inflammation, and ciliated cell extrusion remain unresolved. With the use of ex vivo cultures of human Fallopian tube paired with RNA sequencing we defined the tissue response to gonococcal challenge, identifying cytokine, chemokine, cell adhesion, and apoptosis related transcripts not previously recognized as potentiators of gonococcal PID. Unexpectedly, IL-17C was one of the most highly induced genes. Yet, this cytokine has no previous association with gonococcal infection nor pelvic inflammatory disease and thus it was selected for further characterization. We show that human Fallopian tubes express the IL-17C receptor on the epithelial surface and that treatment with purified IL-17C induces pro-inflammatory cytokine secretion in addition to sloughing of the epithelium and generalized tissue damage. These results demonstrate a previously unrecognized but critical role of IL-17C in the damaging inflammation induced by gonococci in a human explant model of PID.

gga-miR-146c Activates TLR6/MyD88/NF-κB Pathway through Targeting MMP16 to Prevent Mycoplasma Gallisepticum (HS Strain) Infection in Chickens

Mycoplasma gallisepticum (MG), a pathogen that infects chickens and some other birds, triggers chronic respiratory disease (CRD) in chickens, which is characterized by inflammation. The investigation of microbial pathogenesis would contribute to the deep understanding of infection control. Since microribonucleic acids (miRNAs) play a key role in this process, gga-mir-146c, an upregulated miRNA upon MG infection, was selected according to our previous RNA-sequencing data. In this paper, we predicted and validated that MMP16 is one of gga-miR-146c target genes. Results show that MMP16 is the target of gga-miR-146c and gga-miR-146c can downregulate MMP16 expression within limits. gga-miR-146c upregulation significantly increased the expression of TLR6, NF-κB p65, MyD88, and TNF-α, whereas the gga-miR-146c inhibitor led to an opposite result. gga-miR-146c upregulation effectively decreased apoptosis and stimulated DF-1 cells proliferation upon MG infection. On the contrary, gga-miR-146c inhibitor promoted apoptosis and repressed the proliferation. Collectively, our results suggest that gga-miR-146c upregulation upon MG infection represses MMP16 expression, activating TLR6/MyD88/NF-κB pathway, promoting cell proliferation by inhibiting cell apoptosis, and, finally, enhancing cell cycle progression to defend against host MG infection.

Use of Human Fallopian Tube Organ in Culture (FTOC) and Primary Fallopian Tube Epithelial Cells (FTEC) to Study the Biology of Neisseria gonorrhoeae Infection

Epithelial cells represent one of the most important physical barriers to many bacterial pathogens. In the case of Neisseria gonorrhoeae, the epithelial cell response is critical because they are the main target of the tissue damage triggered by the pathogen, particularly when the organism reaches the Fallopian tube (FT). Although the irreversible damage triggered by N. gonorrhoeae in the FT has been previously reported (ectopic pregnancy, pelvic inflammatory disease and infertility), the mechanisms of gonococcal-induced tissue damage are not fully understood. In addition, the lack of animal models that efficiently mimic the human disease and the complexity of gonococcus-host interactions make studying gonococcal pathogenesis particularly difficult. The use of human immortalized cells is also limited, since a variety of commercial FT cell lines is not yet available. Finally, the phase and antigenic variation of many gonococcal surface molecules involved in attachment and invasion of epithelial tissues leads to a failure to reproduce results using different human cells lines used in previous studies. The FT organ in culture (FTOC) and primary human fallopian tube epithelial cell (FTEC) represent the closest ex vivo cell models to explore the biology of Neisseria gonorrhoeae during infection of the FT, since it is a natural host target of the gonococcus. In this chapter, we describe protocols to process human FT samples to obtain FTOC and FTEC and assess their response to infection with Neisseria gonorrhoeae.

Pathogenesis of Neisseria gonorrhoeae and the Host Defense in Ascending Infections of Human Fallopian Tube

Neisseria gonorrhoeae is an obligate human pathogen that causes mucosal surface infections of male and female reproductive tracts, pharynx, rectum, and conjunctiva. Asymptomatic or unnoticed infections in the lower reproductive tract of women can lead to serious, long-term consequences if these infections ascend into the fallopian tube. The damage caused by gonococcal infection and the subsequent inflammatory response produce the condition known as pelvic inflammatory disease (PID). Infection can lead to tubal scarring, occlusion of the oviduct, and loss of critical ciliated cells. Consequences of the damage sustained on the fallopian tube epithelium include increased risk of ectopic pregnancy and tubal-factor infertility. Additionally, the resolution of infection can produce new adhesions between internal tissues, which can tear and reform, producing chronic pelvic pain. As a bacterium adapted to life in a human host, the gonococcus presents a challenge to the development of model systems for probing host-microbe interactions. Advances in small-animal models have yielded previously unattainable data on systemic immune responses, but the specificity of N. gonorrhoeae for many known (and unknown) host targets remains a constant hurdle. Infections of human volunteers are possible, though they present ethical and logistical challenges, and are necessarily limited to males due to the risk of severe complications in women. It is routine, however, that normal, healthy fallopian tubes are removed in the course of different gynecological surgeries (namely hysterectomy), making the very tissue most consequentially damaged during ascending gonococcal infection available for laboratory research. The study of fallopian tube organ cultures has allowed the opportunity to observe gonococcal biology and immune responses in a complex, multi-layered tissue from a natural host. Forty-five years since the first published example of human fallopian tube being infected ex vivo with N. gonorrhoeae, we review what modeling infections in human tissue explants has taught us about the gonococcus, what we have learned about the defenses mounted by the human host in the upper female reproductive tract, what other fields have taught us about ciliated and non-ciliated cell development, and ultimately offer suggestions regarding the next generation of model systems to help expand our ability to study gonococcal pathogenesis.

Pathogenesis of Neisseria gonorrhoeae in the female reproductive tract: neutrophilic host response, sustained infection, and clinical sequelae

PURPOSE OF REVIEW

Gonorrhea is a major global health concern, caused by the bacterium Neisseria gonorrhoeae. The main clinical feature of acute gonorrhea is neutrophilic influx that is unable to clear infection. Women of reproductive age are predominantly at risk for serious sequelae of gonorrhea, including pelvic inflammatory disease, ectopic pregnancy, and infertility. This review will highlight how neutrophils are recruited to the female reproductive tract (FRT) in response to N. gonorrhoeae, how N. gonorrhoeae resists killing by neutrophils, and the connection between neutrophilic inflammation and cellular damage.

RECENT FINDINGS

Epithelial cells and immune cells of the FRT recognize and respond to N. gonorrhoeae lipid A and heptose bisphosphate of lipooligosaccharide, porin, lipoproteins, and peptidoglycan fragments. N. gonorrhoeae skews the resulting immune response toward a neutrophilic, Th17-like response. N. gonorrhoeae has multiple, nonredundant mechanisms to survive inside neutrophils and in neutrophil extracellular traps. Infection that ascends to the upper FRT induces the further release of inflammatory cytokines and matrix metalloproteinases, which cause epithelial damage.

SUMMARY

N. gonorrhoeae is remarkable in its ability to recruit neutrophils, yet survive in their midst. New models being developed for FRT infection with N. gonorrhoeae will be useful to reveal the mechanisms underlying these observations.

Neisseria gonorrhoeae Challenge Increases Matrix Metalloproteinase-8 Expression in Fallopian Tube Explants

Background:Neisseria gonorrhoeae (Ngo) is the etiological agent of gonorrhea, a sexually transmitted infection that initially infects the female lower genital tract. In untreated women, the bacteria can ascend to the upper genital reproductive tract and infect the fallopian tube (FTs), which is associated with salpingitis and can lead to impaired FT function and infertility. The extracellular matrix (ECM) plays an important role in cell migration and differentiation in the female genital tract, and some pathogens modify the ECM to establish successful infections. The ECM is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs), their endogenous inhibitors; MMP deregulation causes pathological conditions in a variety of tissues.

Results: The aim of this work was to analyze the expression and localization of MMP-3, MMP-8, MMP-9, and TIMP-1 in FT explants during Ngo infection using real-time PCR, immunohistochemistry, zymography and ELISA. No significant variations in MMP-3, MMP-9, and TIMP-1 transcript levels were observed. In contrast, a significant increase (p < 0.05) was observed for MMP-8 expression and was accompanied by stromal immunoreactivity in infected explants. ELISA results supported these findings and showed that MMP-8 release increased upon gonococcal infection.

Conclusions: Our results indicate that gonococcal infection induces increased MMP-8 expression, which might contribute to FT damage during infection.