Cervical Squamous Intraepithelial Lesions Are Associated with Differences in the Vaginal Microbiota of Mexican Women.

Cervical cancer is an important health concern worldwide and is one of the leading causes of death 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 precancerous squamous intraepithelial lesions (SIL). We sequenced the V3 region of the 16S rRNA gene in cervical samples from 228 Mexican women, including 121 participants with SIL, most of which were HPV positive, and 107 healthy women without HPV infection or SIL. The presence of SIL was associated with changes in composition (beta diversity) and with a higher species richness (Chao1). A comparison of HPV-positive women with and without SIL showed that microbiota changes occurred even in the absence of SIL. Multivariate association with linear models (MaAsLin) analysis yielded independent associations between HPV infection and an increase in the relative abundance of Brachybacterium conglomeratum and Brevibacterium aureum as well as a decrease in two Lactobacillus iners operational taxonomic units (OTUs). We also identified a positive independent association between HPV-16, the most common HPV subtype linked to SIL, and Brachybacterium conglomeratum. Our work indicates that HPV infection leading to SIL is primarily associated with shifts in vaginal microbiota composition, some of which may be specific to this human population. IMPORTANCE Human papillomavirus (HPV) plays a critical role in cervical carcinogenesis but is not sufficient for cervical cancer development, indicating the involvement of other factors. The 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 infections. Ethnic and sociodemographic factors influence differences in vaginal microbiome composition, which underlies the dysbiotic patterns linked to HPV infection and cervical cancer across different populations of women. Here, we provide evidence for associations between vaginal microbiota patterns and HPV infection linked to ethnic and sociodemographic factors. To our knowledge, this is the first report of the species Brevibacterium aureum and Brachybacterium conglomeratum linked to HPV infection or squamous intraepithelial lesions (SIL).

Asymptomatic Intestinal Colonization with Protist Blastocystis Is Strongly Associated with Distinct Microbiome Ecological Patterns.

Blastocystis is the most prevalent protist of the human intestine, colonizing approximately 20% of the North American population and up to 100% in some nonindustrialized settings. Blastocystis is associated with gastrointestinal and systemic disease but can also be an asymptomatic colonizer in large populations. While recent findings in humans have shown bacterial microbiota changes associated with this protist, it is unknown whether these occur due to the presence of Blastocystis or as a result of inflammation. To explore this, we evaluated the fecal bacterial and eukaryotic microbiota in 156 asymptomatic adult subjects from a rural population in Xoxocotla, Mexico. Colonization with Blastocystis was strongly associated with an increase in bacterial alpha diversity and broad changes in beta diversity and with more discrete changes to the microbial eukaryome. More than 230 operational taxonomic units (OTUs), including those of dominant species Prevotella copri and Ruminococcus bromii, were differentially abundant in Blastocystis-colonized individuals. Large functional changes accompanied these observations, with differential abundances of 202 (out of 266) predicted metabolic pathways (PICRUSt), as well as lower fecal concentrations of acetate, butyrate, and propionate in colonized individuals. Fecal calprotectin was markedly decreased in association with Blastocystis colonization, suggesting that this ecological shift induces subclinical immune consequences to the asymptomatic host. This work is the first to show a direct association between the presence of Blastocystis and shifts in the gut bacterial and eukaryotic microbiome in the absence of gastrointestinal disease or inflammation. These results prompt further investigation of the role Blastocystis and other eukaryotes play within the human microbiome. IMPORTANCE Given the results of our study and other reports of the effects of the most common human gut protist on the diversity and composition of the bacterial microbiome, Blastocystis and, possibly, other gut protists should be studied as ecosystem engineers that drive community diversity and composition.