Nieves-Ramirez, M. | Search bioRxiv

bioRxiv2021

Cervical Squamous Intraepithelial Lesions are Associated with Changes in the Vaginal Microbiota of Mexican Women

Cervical cancer is an important health concern worldwide and is one of the leading causes of deaths in Mexican women. Previous studies have shown changes in the female genital tract microbe community related to Human Papillomavirus (HPV) infection and cervical cancer, yet this link remains unexplored in many human populations. This study evaluated the vaginal bacterial community among Mexican women with pre-cancerous Squamous Intraepithelial Lesions (SIL). We sequenced the V3 region of the 16S rRNA gene (Illumina Miseq) in cervical samples from 300 Mexican women, including 157 patients with SIL, most of which were HPV positive, and 143 healthy women without HPV infection or SIL. Beta-diversity analysis showed that 14.6% of the variance in vaginal bacterial community structure is related to the presence of SIL. Presence of SIL was also associated with a higher species richness (Chao 1). MaAsLiN analysis yielded independent associations between SIL/HPV status and an increase in the relative abundance Brachybacterium conglomeratum, as well as a decrease in Sphingobium yanoikuyae and Lactobacillus spp. We also identified independent associations between HPV-16, the most common HPV subtype linked to SIL, and Brachybacterium conglomeratum. Our work indicates that the presence of SIL and HPV infection is associated with important changes in the vaginal microbiome, some of which may be specific to this human population. IMPORTANCEHPV plays a critical role in cervical carcinogenesis but is not sufficient for cervical cancer development, indicating involvement of other factors. Vaginal microbiota is an important factor in controlling infections caused by HPV and depending on its composition it can modulate the microenvironment in vaginal mucosa against viral infection. Ethnic and sociodemographic factors influence differences in vaginal microbiome composition, which underlies the dysbiotic patterns linked to HPV infection and cervical cancer across different women populations. Here, we provide evidence for associations between vaginal microbiota patterns and HPV infection, linked to ethnic and sociodemographic factor. To our knowledge, this is the first report of Brevibacterium aureum and Brachybacterium conglomeratum species linked to HPV infection or SIL.

microbiology↗

bioRxiv2019

Exposure to parasitic protists and helminths changes the intestinal community structure of bacterial microbiota but not of eukaryotes in a cohort of mother-child binomial from a semi-rural setting in Mexico

Around 3.5 billion people are colonized by intestinal parasites worldwide. Intestinal parasitic eukaryotes interact not only with the host, but also with the intestinal microbiota. In this work, we studied the relationship between the presence of multiple enteric parasites and the community structure of the bacterial and eukaryote intestinal microbiota in an asymptomatic cohort of mother-child binomials from a semi-rural community in Mexico. The intestinal parasites identified were Blastocystis hominis, Entamoeba histolytica/dispar, Endolimax nana, Chilomastix mesnili, Iodamoeba butshlii, Entamoeba coli, Hymenolepis nana and Ascaris lumbricoides. We sequenced bacterial 16S rDNA and eukaryotic 18S rDNA in fecal samples of 46 mothers and their respective children, with ages ranging from two to twenty months. Although we did not find significant alpha-diversity changes, we found a significant effect of parasite exposure on bacterial beta-diversity, which explained between 5.2% and 15.0% of the variation of the bacterial community structure. Additionally, exposure to parasites was associated with significant changes in relative abundances of bacterial taxa, characterized by increases in the Clostridia and decreased Actinobacteria and Bacteroidia abundances. There were no significant changes of intestinal microeukaryote abundances associated with parasite exposure. However, we found several significant positive correlations between intestinal bacteria and eukaryotes, including co-occurrence of the fungi Candida tropicalis with Bacteroides and Actinomyces, and Saccharomycetales with Bifidobacterium and Prevotella copri. These bacterial community structure changes associated with parasite exposure imply effects on microbial metabolic routes, host nutrient uptake abilities and intestinal immunity regulation in host-parasite interactions.\n\nIMPORTANCEThe impact of intestinal eukaryotes on the prokaryotic microbiome composition of asymptomatic carriers has not been extensively explored, especially in children and in hosts with multiple parasites. In this work, we studied the relationship between protist and helminth parasite colonization and intestinal microbiota structure in an asymptomatic population of mother-child binomials from the semi-rural community of Morelos in Mexico. We found that the presence of parasitic eukaryotes correlated with changes in the bacterial community structure in the intestinal microbiota in an age-dependent way. This was characterized by an increase of the relative abundance of the class Clostridia and the decrease of Actinobacteria and Bacteroidia. While there were no significant associations between the presence of parasites and microeukaryote community structure, we observed strong positive correlations between bacterial and eukaryote taxa, identifying novel relationships between prokaryotes and fungi, and reflecting the diet of the human population studied.

microbiology↗