Staphylococcus aureus Fibronectin-Binding Proteins Contribute to Colonization of the Female Reproductive Tract

Interplay between Staphylococcus aureus and the vaginal microbiota

Staphylococcus aureus is a proficient colonizer and opportunistic pathogen which can lead to vaginal dysbiosis, aerobic vaginitis, or life-threatening menstrual toxic shock syndrome. Here we explore the complex but underappreciated interactions that S. aureus may impose on the vaginal environment leading to additional disease outcomes.

Cervicovaginal microbiota disorder combined with the change of cytosine phosphate guanine motif- toll like receptor 9 axis was associated with cervical cancerization

BACKGROUND

Convincing studies demonstrated that cervicovaginal microbiota disorder and toll-like receptor 9 (TLR9) high expression were related to cervical carcinogenesis. However, the effects of cervicovaginal microbiota integration TLR9 in cervical cancerization are unclear. Based on the biological basis that unmethylated cytosine-phosphate-guanine (CpG) motifs of bacteria could activate TLR9, we explored the effects of cervicovaginal microbiota disorder and CpG motif-TLR9 axis change in cervical carcinogenesis.

METHODS

A total of 341 participants, including 124 normal cervical (NC), 90 low-grade cervical intraepithelial neoplasia (CIN1), 78 high-grade cervical intraepithelial neoplasia (CIN2/3) and 49 squamous cervical cancer (SCC), diagnosed by pathology were enrolled in the study. Here, metagenomic shotgun sequencing was used to reveal cervicovaginal microbiota characteristics, and TLR9 protein was detected by western blotting.

RESULTS

Our results showed that the diversity of cervicovaginal microbiota gradually increased along with the poor development of cervical lesions, showing the abundance of Lactobacillus crispatus and Lactobacillus iners decreased, while the abundance of pathogenic bacteria gradually increased. The level of TLR9 expression was gradually increased with cervicovaginal microbiota diversity increasing, the abundance of Lactobacillus decreasing, and we found a positive correlation dependency relationship (r = 0.384, P = 0.002) between TLR9 and GTCGTT motif content. Stratified analysis based on HPV16 infection, we found that the characteristics of cervicovaginal microbiota and increased TLR9 expression were also closely related to HPV16 infection.

CONCLUSIONS

Cervicovaginal microbiota dysbiosis might lead to the CpG motif increased, which was closely associated with TLR9 high expression, and ultimately might promote the progression of cervical lesions.

CD9 co-operation with syndecan-1 is required for a major staphylococcal adhesion pathway

Epithelial colonization is a critical first step in bacterial pathogenesis. Staphylococcus aureus can utilize several host factors to associate with cells, including α5β1 integrin and heparan sulfate proteoglycans, such as the syndecans. Here, we demonstrate that a partner protein of both integrins and syndecans, the host membrane adapter protein tetraspanin CD9, is essential for syndecan-mediated staphylococcal adhesion. Fibronectin is also essential in this process, while integrins are only critical for post-adhesion entry into human epithelial cells. Treatment of epithelial cells with CD9-derived peptide or heparin caused significant reductions in staphylococcal adherence, dependent on both CD9 and syndecan-1. Exogenous fibronectin caused a CD9-dependent increase in staphylococcal adhesion, whereas blockade of β1 integrins did not affect adhesion but did reduce the subsequent internalization of adhered bacteria. CD9 disruption or deletion increased β1 integrin-mediated internalization, suggesting that CD9 coordinates sequential staphylococcal adhesion and internalization. CD9 controls staphylococcal adhesion through syndecan-1, using a mechanism that likely requires CD9-mediated syndecan organization to correctly display fibronectin at the host cell surface. We propose that CD9-derived peptides or heparin analogs could be developed as anti-adhesion treatments to inhibit the initial stages of staphylococcal pathogenesis. IMPORTANCE Staphylococcus aureus infection is a significant cause of disease and morbidity. Staphylococci utilize multiple adhesion pathways to associate with epithelial cells, including interactions with proteoglycans or β1 integrins through a fibronectin bridge. Interference with another host protein, tetraspanin CD9, halves staphylococcal adherence to epithelial cells, although CD9 does not interact directly with bacteria. Here, we define the role of CD9 in staphylococcal adherence and uptake, observing that CD9 coordinates syndecan-1, fibronectin, and β1 integrins to allow efficient staphylococcal infection. Two treatments that disrupt this action are effective and may provide an alternative to antibiotics. We provide insights into the mechanisms that underlie staphylococcal infection of host cells, linking two known adhesion pathways together through CD9 for the first time.