Introduction

Figure 1. Development stages of cervical cancer.

Figure 1. Development stages of cervical cancer.

Cervicovaginal Microbiomes and Host Defenses

According to recent studies, the homeostasis of the cervicovaginal microbiome and the local microenvironment is maintained by their interaction (Caron et al., 2020). However, any imbalance in this equilibrium can lead to chronic inflammation, genome instability, abnormal cellular proliferation, epithelial barrier breach, metabolic dysregulation, and angiogenesis (Caron et al., 2020). To protect the genital tract, the human body relies on the immune response, mucosal epithelial barrier, and lactic acid secretion (Caron et al., 2020).

Figure 2. Causes of Vaginal dysbiosis.

Figure 2. Causes of Vaginal dysbiosis.

Lactic acid secretion is a vital defensive mechanism and is correlated with lactobacilli, which produce lactic acid and maintain a lower pH of 4.5, creating an unfavourable environment for invading pathogens (Caron et al., 2020). This environment serves as a barrier for sexually transmitted pathogens, prevents mucin degradation, and conserves the epithelial barrier by producing bacteriocins (Caron et al., 2020).

In a study, dextro lactic acid was found to provide a protective mechanism against vaginal dysbiosis (Caron et al., 2020). The progression of hrHPV-associated cervical wounds is directly correlated with lactic acid, as it inhibits the development of various sexually transmitted anaerobic agents (Caron et al., 2020). In the case of concurrent infections of both HPV and Chlamydia trachomatis along with the associated cervicovaginal microbiomes, a notable diversity in cervical microbial flora, including anaerobic species like A. vaginae and G. vaginalis, was observed, along with a decreased profile of Lactobacillus in infected women (Caron et al., 2020). In healthy women, a dominant profile was exhibited by Lactobacillus, with significantly less percentage of anaerobic bacteria (Caron et al., 2020). A solitary infection of Chlamydia trachomatis has a great variety of microbiota, while the lactobacillus level remains low (Caron et al., 2020).

Role of Probiotics for HPV

“Probiotics are defined by the World Health Organization (WHO) as “live microorganisms which when administered in adequate amounts confer a health benefit on the host” (WHO, n.d.). Recent studies have shown that certain species of probiotics, such as Lactobacillus, Streptococcus, and Bifidobacterium, can improve the host’s inflammatory and immune response by altering the microbiota (Tensaouti et al., 2019).

One application of probiotics is in the treatment of urogenital infections, where Lactobacilli are commonly used (Wang et al., 2020). In particular, they have been employed to improve the vaginal flora through vaginal acidification, synergistic action, and prevention of bacterial adhesion (Mishra et al., 2018). Although the evidence of efficacy is not conclusive, probiotics have been used in the treatment of sexually transmitted diseases due to their low risk of side effects and ability to promote resistance (Palma et al., 2021). One study by Palma et al. (2021) found that the clearance of cytological abnormalities caused by HPV infection was twice as high in the probiotic group compared to the control group, however, further longitudinal studies are needed to confirm these findings.

Figure 3. Microorganisms involved in probiotics.

Figure 3. Microorganisms involved in probiotics.

Conclusion

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