Endometriosis specific vaginal microbiota links to urine and serum N-glycome

Abstract

Endometriosis is a chronic systemic disease, which results in endometrial-type tissue growing outside the uterus, and affects approximately 10% of reproductive-aged women worldwide. Its aetiology is poorly understood, and there is currently no long-term cure. Development and persistence of the disease depend on several coexisting factors including the vaginal microbiome. However, the role played by this important entity in endometriosis and its systemic involvement is not fully understood. Here, we investigated the vaginal microbiota, the serum and urine glycome, and antibody glycosylation in endometriosis patients. We reveal an endometriosis-specific vaginal microbiota in patients, being distinct from that present in a control group. Endometriosis patients were typified by a loss of the dominant Lactobacillus species, i.e. Lactobacillus iners, increased bacterial diversity and the presence of species such as Anaerococcus senegalensis, Prevotella jejuni, Porphyromonas bennonis and Anaerococcus octavius. The presence of trigalactosylated and triantennary serum glycans and urine core fucosylated mono-antennary glycans from IgG correlated with the vaginal presence of the bacterium A. senegalensis in endometriosis patients. Urine glycans did not differ in endometriosis, but urine IgG identified four novel sulfated glycans differing from serum IgG indicating functional relevance. Our findings contribute to understanding the relationships between the vaginal microbiota and the serum and urine glycome on the one hand, and endometriosis on the other. Further functional studies are warranted.

Keywords: N-glycans; Biomarkers; Endometriosis; Microbiota; Serum; Urine.

Fig. 1

Shotgun metagenomic analysis of vaginal swabs reveal distinct microbiota cohorts in endometriosis samples (n = 40). (A) Distinct vaginal microbiota groups were identified, sample clustering heatmap of most dominant species (top 10) revealed distinct cohorts in the endometrial vaginal swabs. Group1- Lactobacillus crispatus, Group2-Lactobacillus iners, Group3-Lactobacillus gasseri, and Group4- Gardnerella vaginalis dominant. (B) Heatmap of dominant species based on clinical scoring. (C) PCA of samples based on bacteria reveal distinct microbiota groups. (D) PCA of samples based on bacteria respective to clinical scoring revealed distinct groups in the endometrial vaginal swabs. (E) PCOA beta diversity Bray Curtis separation based on bacteria of microbiome groups. (F) PCOA beta diversity Bray Curtis separation based on fungi of clinical cohorts (more details about beta diversity in clinical cohorts are in Table S1B).

Fig. 2

Microbiota groups specific species and alpha diversity. (A) Abundance of four most abundant bacteria in four microbiota cohorts according to their dominant species and (B) alpha diversity based on bacteria in each group.

Fig. 3

Clinical cohorts specific species and alpha diversity. (A) Specific bacteria for endometriosis and (B) associated alpha diversity Simpson based on GO.

Fig. 4

Specific bacteria for endometriosis, separation into clinical stages. (A) Anaerococcus senegalensis and Prevotella jejuni. (B) Porphyromonas bennonia and Anaerococcus octavius. (C) Lactobacillus iners. (D) Heat maps of microbes (joined kingdom) and bacteria found only in endometriosis patients; the relative abundance values are from Table S1A and microbes with their numbers are summarized in Table S1C.

Fig. 5

Glycosylation specific for urine and for endometriosis. (A) Glycome of urine and serum IgG differs and (B) specific glycans correlate with Anaerococcus senegalensis.

Fig. 6

Microbiota group correlations with clinical characteristics. (A) Lactobacillus iners group (microbiota group 2) has most users with antibiotics (Lactobacillus iners correlate with antibiotic use, red colour indicates antibiotic users). (B) Lactobacillus crispatus group (microbiota group 1) correlates with oestradiol levels. (C) Lactobacillus gasseri group (microbiota group 3) correlates with LH levels. (D) Microbiota group 4 is slightly older.

Fig. 7

Representative HILIC-UPLC chromatograms of the N-glycans from. (A) All urine glycoproteins and (B) serum and urine IgG. Labelled are modified glycans found only in the urine IgG samples. Each glycan peak (GP) was numbered and detailed information about the assigned structures are presented in Tables S3 and S5.