Influência da microbiota vaginal na incidência de lesões intraepiteliais cervicais HPV-induzidas

Abstract

The vaginal microbiota is a complex ecosystem formed by aerobic and anaerobic bacteria, which live in dynamic equilibrium. Factors such as immunity and hormonal variations can cause loss of balance, leading to the proliferation of opportunistic pathogens and resulting in diseases. Bacterial vaginosis (BV) is a polymicrobial disease, and may occur in association with other microorganisms, such as Human Papillomavirus (HPV). HPV is the most prevalent in the female sexually active population, being a risk factor for the development of cervical intraepithelial lesions, which may progress to cervical cancer. The aim of this study was to evaluate the microbial diversity of the vaginal ecosystem of women with cervical cellular atypias and carrying HPV. Vaginal fluid and scraped uterine cervix were collected (n = 33 without lesion and n = 41 with lesion) and viral and bacterial DNA was extracted. Glass slides were stained by the Gram method in order to establish the Nugent score for BV evaluation. PCR reaction for HPV genotyping was performed. DGGE-PCR was performed to assess the structure of the bacterial community. The mean age of the women was 36 years; comprising 87% (without lesion) and 92% (with lesion). Analysis of the Nugent score revealed that 51% of the women with lesion did not present BV and 29% had BV. Pap smear test showed that 31% of the women had atypical squamous cells of undetermined significance (ASC-US), 26% had low grade squamous epithelial lesion (LSIL), 26% had high grade squamous epithelial lesion (HSIL) and 14% had with atypical squamous cells that do not allow the exclusion of high-grade lesion (ASC-H). HPV was detected in 91% of the patients, being identified 5 types of the high risk group (16, 18, 31, 52 and 58). HPV 16 was the most frequent (85%), followed by HPV 18 (68%). In the non-lesion group, the prevalence of HPV 16 and 18 concomitance was 58% and in the lesion group it was 60%. In the 18-30 age group, 43% of the women had HPV 16, and 35% had coinfection by HPV 16 and 18. The association between genotyping and the Pap smear showed that 40% of ASC- US patients and 20% ASC-H showed monoinfection by HPV 16. Besides, out of women with HPV 16 and coinfection by HPV 16 and 18, BV was found in 25%. In the analysis of the grouping obtained by PCR-DGGE it is observed with some exceptions, that the profiles of women with the same health conditions (healthy, intermediate and with bacterial vaginosis) tended to group, although in separate groups. Analysis of the cluster in relation to the atypia did not observe the formation of a pattern. Given the complexity of the vaginal ecosystem, it is suggested the need for higher resolution power techniques for understanding the relationship between HPV, vaginal microbiota and cervical cellular lesions.