Frideborg Bradley , Kenzie Birse [2,3], Klara Hasselrot [1,4], Laura Romas [2,3], Andrea Introini , Hugo Wefer [5,6], Maike Seifert [5,6], Lars Engstrand [5,6], Annelie Tjernlund , Kristina Broliden , Adam Burgener [1,2,3]
Affiliates:  Unit of Infectious Diseases, Department of Medicine Solna, Karolinska University Hospital, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.  National HIV and Retrovirology Labs, JC Wilt Infectious Disease Centre, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.  Department of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.  Department of Gynaecology, Danderyds Hospital, Stockholm, Sweden.  Department of Microbiology, Tumor and Cell Biology and Science for Life Laboratory, Karolinska Institutet, Sweden.  Clinical Genomics Facility, Science for Life Laboratory, 171 65 Solna, Sweden
Susceptibility to sexually transmitted infections (such as HIV) in the female genital tract (FGT) is affected by local inflammation, but the impact of cyclical changes in sex hormones levels in the context of the microbiome are not well understood. We here longitudinally characterized mucosal host proteome and inflammatory cytokines alongside cervicovaginal microbial community structure and function during the menstrual cycle to better understand these influences.
Cervicovaginal secretions were collected from regularly cycling women (n=16) at three time points during a menstrual cycle followed by analysis by mass spectrometry, multiplex bead-array, and 16S rDNA sequencing. Follicular, ovulatory, and luteal phases of the menstrual cycle were defined by serum sex hormones levels.
Significant mucosal proteome changes occurred between phases, the largest of which occurred during ovulation, where 30% and 19% of the 406 proteins identified were differentially abundant (p<0.05, Log2-fold change ≥1) compared to the luteal and follicular phases, respectively. Neutrophil/leukocyte migration pathways and pro-inflammatory cytokines were suppressed during ovulation and peaked during luteal phase, while antimicrobial, tissue homeostasis, and epithelial barrier promoting proteins increased during ovulation (p<0.05, Z score ≥2). Vaginal microbial communities did not vary significantly during the menstrual cycle, with the majority consistently Lactobacillus-dominant (63%) or non-Lactobacillus-dominant (25%), but cycle-dependent fluctuations in inflammation during luteal phase were amplified in women with Gardnerella vaginalis and other non-Lactobacillus bacteria.
Endogenous sex hormones modulate neutrophil/leukocyte inflammation and barrier function pathways in the FGT with the strongest changes occurring during ovulation, which are exacerbated by vaginal bacteria. This shows novel information on cyclic sex hormone influences on mucosal immunity and the importance of the microbial context in these processes.