Enhanced IgA coating of bacteria in women with Lactobacillus crispatus-dominated vaginal microbiota

Abstract

Background Immunoglobulin A (IgA) plays an important role in maintaining a healthy intestinal microbiome, but little is known about the interaction between local immunoglobulins and the vaginal microbiome. We assessed immunoglobulins (unbound and bound to bacteria), their association with vaginal microbiota composition and the changes over time in 25 healthy women of reproductive age. Results In both Lactobacillus crispatus-dominated and non-L. crispatus-dominated microbiota, IgA and IgG (unbound and bound to bacteria) were higher during menses (T = 1) compared to day 7‑11 (T = 2) and day 17‑25 (T = 3) after menses onset. The majority of vaginal bacteria are coated with IgA and/or IgG. Women with L. crispatus-dominated microbiota have increased IgA coating of vaginal bacteria compared to women with other microbiota compositions, but contained less IgA per bacterium. Presence of a dominantly IgA-coated population at T = 2 and/or T = 3 was also strongly associated with L. crispatus-dominated microbiota. In women with non-L. crispatus-dominated microbiota, more bacteria were uncoated. Unbound IgA, unbound IgG, and bound IgG levels were not associated with microbiota composition. Conclusions In conclusion, L. crispatus-dominated vaginal microbiota have higher levels of bacterial IgA coating compared to non-L. crispatus-dominated vaginal microbiota. Similar to its regulating function in the intestinal tract, we hypothesize that IgA is involved in maintaining L. crispatus-dominated microbiota in the female genital tract. This may play a role in L. crispatus-associated health benefits.

Female reproductive tract-organ axes

“…IgA-coated L. jensenii , not IgA-free lactic acid bacterial strains, from the fecal microbiota of a healthy woman significantly inhibits dyslipidemia and gut barrier damage in high-fat diet-fed mice ( 199 ). As mentioned above, IgA-coated bacteria are observed more frequently in vaginal microbiota with L. crispatus dominance compared with that with non- L. crispatus -dominant microbiota ( 84 ). Therefore, IgA-coated L. crispatus as a probiotic might colonize the vagina longer than current probiotic strains.…”

“…In contrast, most bacteria in the Firmicutes phylum were not coated with IgA ( 83 ). Of note, Breedveld and colleagues recently reported that higher levels of bacterial IgA coating were observed when the vaginal microbiota was dominated by L. crispatus compared with non- L. crispatus -dominated microbiota ( 84 ). The bacterial IgA coating might modulate biogeography, metabolic processes, proliferation, and survival in mucosal tissue by modifying bacterial gene expression ( 85 , 86 ).…”

“…IgA coating is proposed to promote adhesion to the mucus layer and facilitate the formation of bacterial biofilms on the mucosal surface, which is important for bacterial colonization in the gut ( 87 ). Therefore, similar to its regulatory function in the GI tract, IgA could play a role in maintaining the L. crispatus -dominated microbiota ( 84 ). A previous study showed that genetic variants of IL-5 were associated with the abundance of Prevotella spp.…”

The impact of pelvic floor electrical stimulation on vaginal microbiota and immunity

“…L. crispatus is related to defense against infections and regulates anti-inflammatory reactions. Microbiomes, dominated by L. iners , are more likely to transfer to a diverse microbiome than L. crispatus preponderance ( Mitra et al., 2020 ; Breedveld et al., 2022 ). These mechanisms may account for the rise in L. crispatus abundance seen in this study following ES.…”

Role of the human vaginal microbiota in the regulation of inflammation and sexually transmitted infection acquisition: Contribution of the non-human primate model to a better understanding?

“…Annelot C. Breedvelt et al demonstrated that women with a L. crispatus dominated microbiota had a higher level of bacterial IgA coating compared to non- L. crispatus dominated microbiota. The authors suggested that a higher level of unbound bacteria with IgA in non- L. crispatus dominated microbiota might be associated with inflammation, and therefore a higher susceptibility to infection ( 133 ).…”