In addition to being a passage for sperm, menstruum, and the baby, the human vagina and its microbiota can influence conception, pregnancy, the mode and timing of delivery, and the risk of acquiring sexually transmitted infections. The physiological status of the vaginal milieu is important for the wellbeing of the host as well as for successful reproduction. High estrogen states, as seen during puberty and pregnancy, promote the preservation of a homeostatic eubiotic vaginal microenvironment by stimulating the maturation and proliferation of vaginal epithelial cells and the accumulation of glycogen. A glycogen-rich vaginal milieu is a haven for the proliferation of Lactobacilli facilitated by the production of lactic acid and decreased pH. Lactobacilli and their antimicrobial and anti-inflammatory products along with components of the epithelial mucosal barrier provide an effective first line defense against invading pathogens including bacterial vaginosis, aerobic vaginitis-associated bacteria, viruses, fungi and protozoa.
Vaginal milieu these reasons a lactobacilli-dominated vaginal microbiota has been described as healthy and necessary for the overall wellbeing of the woman. The effect upon the human vaginal histology of the long-term use of the injectable contraceptive Depo-Provera. Sundquist, A. Aetiology of preterm labour: bacterial vaginosis. The Vaginal milieu of lactic acid production by probiotic Lactobacillus species in vaginal health. Vet Miliu 49—, Newman, T.
Girls strapon man sex. Introduction
Oxford University Press is a department of the University of Oxford. Vaginal milieu The vaginal milieu refers to the various constituents and micro-organisms resident in the secretions of the vagina. Physical examination of the genitalia reveals erythema and tenderness of the vulvovaginal area. Since then, the patient has remained asymptomatic and culture negative. Make the changes yourself here! All other culture sites, including the nose and throat, had Vaginal milieu with negative culture results. After each course of antibiotic therapy, the Vaginal milieu symptoms improved, and although her vaginal culture results became temporarily negative for S. Related articles in Web of Science Google Scholar. At that time, the patient's throat culture also was positive Bras at bare GAS. This is effective in the majority of cases. Kero 1 2 Email author J.
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- Cervical ectropion occurs when there is eversion of the endocervix, exposing the columnar epithelium to the vaginal milieu.
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In addition to being a passage for sperm, menstruum, and the baby, the human vagina and its microbiota can influence conception, pregnancy, the mode and timing of delivery, and the risk of acquiring sexually transmitted infections. The physiological status of the vaginal milieu is important for the wellbeing of the host as well as for successful reproduction.
High estrogen states, as seen during puberty and pregnancy, promote the preservation of a homeostatic eubiotic vaginal microenvironment by stimulating the maturation and proliferation of vaginal epithelial cells and the accumulation of glycogen. A glycogen-rich vaginal milieu is a haven for the proliferation of Lactobacilli facilitated by the production of lactic acid and decreased pH. Lactobacilli and their antimicrobial and anti-inflammatory products along with components of the epithelial mucosal barrier provide an effective first line defense against invading pathogens including bacterial vaginosis, aerobic vaginitis-associated bacteria, viruses, fungi and protozoa.
An optimal host-microbial interaction is required for the maintenance of eubiosis and vaginal health. This review explores the composition, function and adaptive mechanisms of the vaginal microbiome in health and those disease states in which there is a breach in the host-microbial relationship.
The potential impact of vaginal dysbiosis on reproduction is also outlined. The vaginal mucosal ecosystem is comprised of a stratified squamous non-keratinized epithelium overlaid by a mucosal layer continuously lubricated by cervicovaginal fluid CVF. Together, these form a daunting physical and biochemical barrier against extraneous invading organisms. Eubiotic effect of estrogen and Lactobacillus species in the vaginal milieu. At puberty and during pregnancy, elevated levels of estrogen promote the maturation of and deposition of glycogen in vaginal epithelial cells.
Lactic acid and cytolysin produced by Lactobacilli stimulate the dissolution of epithelial cells by lysis and enhance the availability of glycogen. Lactic acid acidifies the vaginal milieu favoring the proliferation of Lactobacilli and inhibiting the growth of infection-associated organisms.
This is reinforced by Lactobacilli through the production of hydrogen peroxide H 2 O 2 , bacteriocins and biosurfactants, as well as the inhibition of the physical attachment of pathogens to the epithelium by competitive exclusion and the promotion of the engulfment and degradation of infected epithelial cells autophagy. Some of these microorganisms such as Lactobacillus species reinforce the defense against invasion and colonization by opportunistic pathogens.
A number of protective Lactobacillus species dominates the healthy vaginal microbiota in most reproductive-age women. Recent advances in DNA sequencing techniques have revealed that the dominant Lactobacillus species in the vaginal microbiota include L.
Differences in prevalence are also related to lifestyle differences 11 and gene-environment interactions Unlike other body viscera such as the gut, increased diversity of the vaginal microbiota is linked to increased susceptibility to disease and negative reproductive outcomes 5 , In addition to epithelial cells and microbiota, the vagina also contains immune-related cells such as neutrophils, macrophages, T and B cells, natural killer NK cells, etc.
Other immune factors including macrophages, NK cells, helper and cytotoxic T cells as wells as B-lymphocytes are subsequently recruited to mount appropriate immune responses.
Such pathogen-stimulated inflammatory responses normally control infection but can in some instances breach the mucosal surface and facilitate transmission of some other infections such as HIV 1. Therefore, vaginal communities dominated by anaerobes are potentially associated with greater pro-inflammatory response than L.
However, Lactobacilli and lactic acid via multiple mechanisms as discussed below promote antimicrobial defense without inducing immune-mediated inflammation unlike the pathogenic anaerobes 3. The prepubertal vaginal microbiome is dominated by anaerobes, E. At puberty, the rising levels of estrogen promote the maturation, proliferation and accumulation of glycogen in the vaginal epithelial cells.
This creates an acidic environment pH, 3. Lactobacilli dominance decreases as estrogen levels decline following menopause 16 , and increases with vaginal estrogen replacement therapy. The vaginal microbiota in normal pregnancy is predominated by Lactobacilli and is more stable than that in the non-pregnant state 12 , 17 , This can be explained by the high level of estrogen during pregnancy resulting in increased vaginal glycogen deposition which enhances the proliferation of Lactobacilli -dominated vaginal microbiota 2.
Also, studies have shown that menstruation significantly reversibly alters the vaginal microbial diversity, with about a fold decrease in L. In essence, the normal acidic vaginal pH in reproductive-age women is driven by estrogen, glycogen, and Lactobacilli 1 , 21 — An intriguing direct relationship between vaginal ostrogenization and candidiasis in postmenopausal women has also been reported After menopause, estrogen-induced vaginal epithelial glycogen accumulation is associated with increased infection by Candida albicans that has glycogen as a major substrate.
This effect of vaginal ostrogenization, glycogen level and candidiasis in relation to menopausal status is likely to be of physiologic importance and necessitates further investigation. Vaginal lactic acid is predominantly of bacterial origin Of the four most common vaginal Lactobacillus species, only L.
D-lactic acid is more protective against vaginal dysbiosis than L-lactic acid Its levels are highest when L. Lactic acid at physiological concentrations e. Specifically, distinct from its bactericidal activity D-lactic acid inhibits Chlamydia infection through a pH-dependent effect on the vaginal epithelial cells and microenvironment This conclusion arose from the significantly greater protection against chlamydia provided by L. Also, D-lactic acid prevents upper genital tract infection by modulating the L-lactic acid-induced production of extracellular matrix metalloproteinase inducer EMMPRIN from vaginal epithelial cells, and inhibiting the production of MMP-8 The precise mechanism of the bactericidal activity of Lactobacillus is unclear but there is evidence that it is mediated through the protonated forms of both D- and L-lactic acid and not the lactate anion Lactic acid in its protonated form is membrane-permeant and unlike the lactate anion, does not require the proton-linked monocarboxylate transporters or the lactate-binding GPR81 receptors to enter cells 37 , Lactic acid preferentially lyses bacteria other than Lactobacillus species 23 , 36 ; and causes bacterial cell death by acidifying the cytosol, disrupting intracellular function 39 , increasing the permeability of the cell membrane to H 2 O 2 , diacetyl etc.
The reduced antimicrobial activity of lactic acid and increased risk of infection associated with unprotected sexual intercourse and menstruation could be attributed to the increase in vaginal pH after deposition of seminal fluid and flow of menstruum, which leads to formation of more lactate anion that has less antimicrobial and immunomodulatory activities 33 , Lactic acid also performs some immunomodulatory actions on the genital tract mucosa and other cell types 41 , Also, both D- and L-lactic acid can enhance vaginal epithelial cell survival by facilitating the repair of damaged DNA through the inhibition of histone deacetylase activity leading to increased acetylation of histones on the surface of DNA 45 , This epigenetic regulation of gene expression 45 permits the transcription of genes that were previously blocked and possibly promotes the secretion of components of the antimicrobial innate immune system, such as NGAL from vaginal epithelial cells, that selectively prevent the growth of bacteria other than lactobacilli 3 , These observations show great promise for the use of lactic acid-containing microbicides for therapeutic restoration of vaginal homeostasis and prevention of STIs including HIV.
Lactobacilli apart from L. They can also bind to the surface of vaginal epithelium and competitively prevent other microbes from attaching to and infecting the cells.
Hence, through these mechanisms, lactobacilli inhibit the growth of other potentially pathogenic endogenous vaginal bacteria and prevent the acquisition of exogenous bacteria. For these reasons a lactobacilli-dominated vaginal microbiota has been described as healthy and necessary for the overall wellbeing of the woman. These women have been found to harbor other lactic acid producers such as Atopobium, Megasphaera, Leptotrichia, Streptococcus , and Staphylococcus 50 , In addition, the degree of protection conferred on the vaginal ecosystem is dependent on the predominant Lactobacillus specie.
For example, an L. In contrast L. It has a small genome and is unable to produce D-lactic acid and H 2 O 2 required to promote eubiosis, unlike the other Lactobacillus species 3 , Also, we recently observed that preponderance of L. The mucosal surface of the vagina is an immunological and physical barrier that prevents potential pathogens from coming in contact with vaginal epithelial cells.
It contains glycosylated mucus proteins sialoglycoproteins such as mucin that provide a dense lubricated physical barrier, which inhibits epithelial cell-pathogen contact; and secretory immunoglobulin A sIgA and IgG that recognize and neutralize antigenic microbial products. Anaerobes associated with vaginal infection such as G. Sialic acid is taken up and neutralized by G. A significant depletion of mucus sialic acids is seen in BV-infected women compared to their healthy counterparts with Lactobacillus-dominated microbiota Degradation and depletion of the components of the mucosal protective barrier permits ascending upper genital tract infection.
In addition, like L. Contrarily, the protective function of the mucus layer is enhanced by L. Therefore, alterations in the composition of the vaginal microbial community significantly affects the integrity of the protective mucosal surface layer 5. The influence of stress on vaginal immunity has been the subject of much speculation. Immune response may be impaired by stress-related activation of the hypothalamic-pituitary adrenal HPA axis and secretion of corticotropin-releasing hormone CRH from the hypothalamus, which activates the release of cortisol from the adrenal cortex and noradrenaline from sympathetic nerve terminals Cortisol inhibits the estrogen-associated vaginal epithelial maturation and accumulation of glycogen and consequently reduces lactobacilli dominance, while noradrenaline acts synergistically with immune mediators to potentiate the release of cytokines.
The stress-induced increase in cortical hormones - cortisol and deoxycorticosterone - and the resultant decrease in lactobacilli abundance can worsen vulvovaginal symptoms of infection Reduced vaginal epithelial glycogen decreases the production of lactic acid and loss of its anti-inflammatory activities.
Hence, a dysbiotic vaginal flora is created characterized by a reduction or loss of lactobacillus dominance. Concomitant increase in noradrenaline potentiates the pro-inflammatory response and proliferation of pathogenic strict and facultative anaerobes as well as other STIs.
Ultimately, stress exacerbates the susceptibility and severity of vaginal infection 3. The vaginal microbiota is a dynamic community of diverse bacterial species repeatedly subjected to both internal and external manipulative stimuli such as changes in sex hormone levels and stage of the menstrual cycle, sexual activity, antibiotic therapy and the use of oral contraceptives, vaginal douching, menopause, pregnancy, lactation, diabetes mellitus and stress.
The composition of the vaginal microbiota is also determined by gene-environment interactions. Vaginal bacterial communities devoid of Lactobacillus dominance with higher pH and lower H 2 O 2 have been observed to be normal in Black and Hispanic women 11 , 52 , 60 , The most common vaginal infection in reproductive-aged women is bacterial vaginosis BV.
BV is an enigmatic syndrome with unidentified etiology. Most BV-positive women are usually asymptomatic. However, symptoms could appear in the form of a non-itchy but irritating, creamy vaginal discharge with a fishy odor that may be more prominent after sexual intercourse and during menstruation.
The Amsel criteria are used to diagnose BV in most clinical settings. In the research space, BV is commonly diagnosed with the Nugent scoring system Although the diagnosis requires experienced laboratory staff to evaluate the slides, it is more objective and reliable and has a higher reproducibility and sensitivity compared to the Amsel criteria There is a good correlation between clinical features of BV and Gram stain scores Vaginal dysbiosis can also manifest as aerobic vaginitis AV. It is an equally disruptive infection of the normal vaginal Lactobacillus -dominated microbiota but is characterized by overt inflammation, leukocyte and parabasal cell infiltration and proliferation of enteric aerobic bacterial organisms including Escherichia coli, Enteroccoci, Staphylococcus aureus , and group B Streptococcus 21 , It has been described as the aerobic equivalent of BV, due to decreased lactic acid concentration secondary to depleted Lactobacillus dominance.
However, because anaerobes are absent, succinate concentration is low. The physiological status of the vaginal milieu is crucial not just to the general wellbeing of the host but also for conception and eventual success of pregnancy. The ability of Lactobacillus to preclude the invasion and colonization of the vaginal space by pathogens without triggering an overt inflammatory response is termed Tolerance and is particularly beneficial for reproduction 3.
Apart from increasing the host's susceptibility to STIs and other gynecological conditions including cervical intraepithelial neoplasia and cervical cancer 85 — 87 , a dysbiotic vaginal microenvironment with degraded Lactobacilli-mediated tolerance and anti-inflammatory mechanisms also influence the course and outcome of pregnancy.
In essence, Lactobacillus spp. Diminished vaginal Lactobacillus dominance has been linked to failure of in vitro fertilization IVF and miscarriage
Only after treatment of the partners following the patients' clindamycin therapy was resolution of the recurrences achieved. The last course of antibiotic therapy was completed 1 week prior to her referral to our clinic Wayne State University Vaginitis Clinic; Detroit, Michigan. Permissions Icon Permissions. Grenman 1 S. Add comment Cancel. Carriage or exposure to a carrier is an important pathogenic factor in recurrent GAS infection, although it is often ignored. Giant pelvic abscess with sepsis: Case report and review of current literature.
Vaginal milieu. Acknowledgments
At that time, the patient's throat culture also was positive for GAS. Culture of a perianal sample obtained from the patient's husband was positive for GAS, as was a stool culture; however, a throat culture showed no growth. Typing of the vaginal GAS isolates from the index patient and the GAS isolates obtained from her husband revealed the strains to be identical T agglutination pattern 28, M protein [ emm sequence] Three children had samples cultured, none of whom had oral or rectal cultures positive for GAS.
The patient was treated with clindamycin mg 4 times per day for 5 days, and her husband received penicillin G mg 4 times per day for 10 days. One week after finishing her treatment, the patient reported resolution of her symptoms, which was confirmed by a significant decrease in erythema and swelling on physical examination of her genitals.
Her vaginal culture was negative for GAS. On her follow-up visits, she remained asymptomatic and culture negative. However, cultures of her husband's perianal samples continued to be positive for GAS 2 weeks after completing the course of oral penicillin. Accordingly, he was treated with moxifloxacin administered at a dose of mg daily for 14 days, and the patient was treated with moxifloxacin mg daily for 7 days. Since then, the patient has remained asymptomatic and culture negative.
Her husband has also remained rectal culture negative throughout a 6-month follow-up period. Patient 2 was a year-old woman who was referred to our clinic because of recurrent episodes of vulvovaginitis over a 6-month period, characterized by pruritus, vaginal discharge, and vulva redness and swelling.
She received several courses of both antimycotic and antibacterial therapy from her family practitioner, with only short-term benefit. It is noteworthy that, on 2 occasions, cultures of vaginal and urine samples were found to be positive for S.
She saw a urologist and a gynecologist, but her illness remained undiagnosed; she was given empirical anti—herpes virus therapy, because her type 2 herpes simplex virus : IgG titer was elevated. Physical examination revealed diffuse erythema of the patient's vulva, vestibule, and vagina, together with the presence of copious purulent secretions. Vaginal pH was elevated at 4.
Vaginal and rectal cultures but not throat cultures were positive for GAS. Similarly, cultures of rectal samples but not of throat samples obtained from the patient's husband were positive for GAS.
Cultures of throat samples obtained from the patient's 3 children showed no growth. The patient's husband received oral levaquin mg daily for 28 days. The patient returned 28 days after the initiation of therapy and was entirely asymptomatic; she had normal physical examination findings, and both vaginal and rectal cultures were negative for GAS. Similarly, her husband's rectal culture was negative for GAS. Further follow-up 3 months later confirmed clinical cure. GAS vaginitis is a rare condition, most often found in prepubertal girls and rarely found in adult women [ 1—5 ].
Patients complain of a purulent vaginal discharge, discomfort, and itching. Dysuria, pain, and bleeding have also been reported. Physical examination of the genitalia reveals erythema and tenderness of the vulvovaginal area. Light microscopic examination of Gram-stained vaginal secretions reveals gram-positive cocci in chains, as well as many polymorphonuclear leukocytes. Thus, GAS is seldom present in the normal vaginal milieu and is rarely the cause of vaginitis in adult women.
Carriage or exposure to a carrier is an important pathogenic factor in recurrent GAS infection, although it is often ignored.
Although mostly found in the nasopharynx, GAS can colonize the perineum, anus, vagina, and normal skin [ 4 , 9—14 ]. Skin colonization is mostly noted in people with dermatological conditions, such as psoriasis, eczema, and wounds. Patients with GAS pharyngitis spread the bacteria through droplets and physical contact.
Gastrointestinal and perianal carriage may be evident in patients with pharyngitis even after pharyngeal infection has resolved and negative pharyngeal culture results have been obtained [ 9 ]. Perianal S. Air contamination can also result from carriers, regardless of the colonized site [ 9 , 15 ]. Reported outbreaks in health care facilities are infrequent but are indicative of serious complications [ 10 , 15—18 ].
One study that reviewed postoperative wound infections due to GAS revealed GAS carriage by staff members, most often anesthesiologists and nursing staff members [ 16 ]. The anus and vagina were the most common carrier sites involved [ 14 ]. Relapse was also common months after treatment, often as the result of a GAS carrier in the patient's household.
It is unclear how long a colonized health care worker must be monitored. Following several months of recurrent GAS vulvovaginitis, evaluation of the patient's families revealed only anorectal carriage in both husbands. All other culture sites, including the nose and throat, had samples with negative culture results. Characterization of the GAS isolates demonstrated identical strains in respective partners.
Only after treatment of the partners following the patients' clindamycin therapy was resolution of the recurrences achieved. After the failure of penicillin G therapy to eradicate intestinal carriage in the first patient's husband, a high-dose, prolonged regimen of oral quinolones successfully eradicated GAS in the gut.
We believe, on the basis of the negative vaginal culture results obtained after treatment of each individual episode of vaginitis, that the women were reinfected as the result of exposure to their male partners. Shedding is likely to have occurred in bed. The first couple was not sexually active throughout the period of recurrent vaginitis.
However, in the second couple, sexual transmission could not be ruled out. These cases reiterate the necessity for adequate screening of the patient's family and contacts in cases of recurrent GAS infection by culturing all possible areas of carriage. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.
Sign In or Create an Account. Sign In. Advanced Search. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents. Reprints or correspondence: Dr. Transl Res — BMC Infect Dis Infect Dis Obstet Gynecol Vaginal infections and prematurity study group. Am J Obstet Gynecol — Diagnostic criteria and microbial and epidemiologic associations. PLoS One 9:e J Clin Microbiol — J Reprod Immunol — PLoS One 8:e J Biol Chem — J Infect Dis — PLoS One 7:e ISME J — BJOG — Kero 1 2 Email author J.
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Hormonal Contraceptive Effects on the Vaginal Milieu: Microbiota and Immunity | SpringerLink
Sign up to take part. A Nature Research Journal. The microbiota fulfils a key role in the training and function of the immune system, which contributes to the symbiosis between the host and complex microbial communities. The abundance of Gardnerella vaginalis and Bifidobacterium breve was increased in the intermediate dysbiotic status, while the presence of a plethora of non-resident bacteria characterized the group with overt vaginosis.
Summarizing, we postulate that although the dysbiotic condition triggers a pro-inflammatory process, the presence of a steady state level of Th2 may influence clinical manifestations.
These results raise clinically relevant questions regarding the use of vaginal immunological markers as efficacious tools to monitor microbial alterations.
The female reproductive tract harbours a symbiotic community that consists of host cells and bacterial communities 1. Indeed, the vaginal mucosa is susceptible to the entry of pathogens, where both local immune mediators and commensal microorganisms are the first line of host defence 6 , 7 , 8.
BV is caused by a reduction of the commensal Lactobacillus spp. Thus, BV is a polymicrobial disease 11 , 12 , 13 in which a single pathogen is not able to induce the disease.
The predominance of Lactobacillus spp. Although approximately half of BV cases are clinically asymptomatic 17 , an increase of local pro-inflammatory effectors has been observed in women with BV 18 , Recent studies have reported the existence of biotic signals that are conducive to a vaginal protective function In this network, cytokines are interspecies communication molecules that coordinate the interactions of vaginal communities, including the growth of pathogenic microorganisms 21 , However, the clinical impact of the modulation of cytokines on vaginal dysbiosis remains to be elucidated.
In women with an intermediate Nugent score, we observed that the overgrowth of Gardnerella vaginalis was balanced by a high colonization of Bifidobacterium breve , which, overall, was able to guarantee a healthy vaginal equilibrium. Conversely, in women with BV, we observed a massive increase of non-resident vaginal species that paralleled a low presence of G.
Among the tested immune mediators, a significant association of the modulation of specific resident bacterial communities was highlighted for IL5 and IL The increase in the concentration of these two anti-inflammatory proteins was accompanied by a depletion of Lactobacilli ssp. We identified 15, operational taxonomic units OTUs across all the samples. Overall, across the five metrics used, the intermediate and vaginosis groups showed higher alpha diversities than the healthy group.
When accounting for the bacterial communities in the cohorts Fig. The vaginal bacterial communities from patients with eubiotic and dysbiotic microbiota. Healthy women exhibited three predominant Lactobacilli species, namely L. Among the other microorganisms detected, the intermediate group showed an increase of Gardnerella vaginalis Actinobacteria and Ureaplasma parvum Tenericutes compared to the vaginosis and healthy groups. Bifidobacterium breve was only detected in the intermediate group.
We assessed which OTUs were discriminative between cohorts, and significant differences of bacterial species were not observed according to the FDR p value.
We next compared the overall microbial diversity between groups using the unweighted and weighted UniFrac distance matrices. As expected, the bacterial composition of these vaginal communities clustered according to the clinical grouping. Each dot represents a sample. A specific pattern of soluble immune mediators distinguished the grade of vaginal dysmicrobism.
To evaluate the possible relationship between the local immune response and the bacterial composition, the concentrations of each immune factors were included as variables in the BIO-ENV rank-correlation procedure, where single variables or combinations of variables are selected based on how they best explain differences among samples.
Based on the weighted UniFrac distance matrix, several immune factors showed a high correlation with the different microbial patterns observed among samples. Next, we explored whether any individual bacterium correlated with an increase or decrease of specific immune factors.
The use of high-throughput sequencing techniques shed new light on the high variability and complexity of the vaginal microbiome. Our in vivo results agree with recent studies that have shown that Nugent score, based on the quantification of only three bacterial morphotypes, is not sufficiently informative to clearly define a vaginal dysbiotic status Consistent with this issue is the observation of a high colonization by Bifidobacterium breve , neglected by Nugent Score, in the vaginal microbiome of women with an intermediate dysmicrobism.
It is noteworthy that, by neglecting the presence of all lactate producing bacteria and the identification of Lactobacilli species, the Nugent score criteria led to the overestimation of the dysbiotic status and to an unnecessary therapeutic intervention being suggested. In addition, the Nugent score neglects the dynamic of interspecies communication between specific species of Lactobacilli and opportunistic pathogens.
In the group of healthy women, L. The novelty of our study consists of the in vivo demonstration that specific vaginal immune profiles significantly correlate with the microbial composition and clinical manifestation. This finding may help in the diagnosis of BV, predict the recurrence of vaginal dysbiosis and help follow the recovery after treatment.
We observed that a subset of pro-inflammatory mediators, typically involved in the chronic inflammation process, synergized with a subset of cytokines that are involved in the switch toward the Th2 immune response.
This network likely supports a dysbiotic condition, regardless of the host pro-inflammatory Th1 response, which is normally effective at restoring the eubiosis state. More precisely, the women with an intermediate Nugent Score showed a significant decrease in several pro-inflammatory cytokines, including IL3 28 and IL17 This event, together with the poor T cell-stimulating activity of G.
Moreover, B. This mechanism may support a biotic balance assuring a healthy vaginal milieu. In women with vaginosis, a massive pro-inflammatory response was observed, supported by a significant increase of IL18 32 , a constituent of the inflammasome complex This observation confirms the results of previous in vitro studies that showed an immunological shift towards a Th1-dominated profile during episodes of bacterial dysmicrobism A new observation that emerged from our study is the significant association between specific commensal microorganisms and the modulation of local cytokines and chemokines, some of which have never been described before.
Specifically, IL5 and IL13, which are secreted by Th2 cells 35 and are known to inhibit both the cell-mediated immune response and several macrophage functions, were statistically associated with Lactobacilli , Gardnerella and Ureaplasma species.
The increase of the two anti-inflammatory cytokines is expected to significantly rise in asymptomatic women with an altered microbiome, explaining the absence or the weakness of symptoms.
Furthermore, the steady-state Th2 response, together with a blunted Th1 response, could lead to immunologic tolerance causing chronic recurrent vaginal dysbiosis Since IL5 and IL13 are strongly influenced by the alteration of eubiotic conditions, regardless of the specific pathogens causing the alteration of vaginal milieu, they could be further studied as indirect markers of vaginal disorder.
Taken together, our findings provide new in vivo insights into how different commensal bacterial species preserve the vaginal symbiotic equilibrium through their interplay with specific local immune mediators. These results raise clinically relevant questions regarding the role of vaginal immunological markers as crucial tool of surveillance of microbial alteration. Sixty-two immunocompetent women who fulfilled the inclusion eligibility criteria were included in this study.
Vaginal samples were collected 7 days before the first day of the menstrual period. Negative controls, including a no template control, were processed with the clinical samples. QIIME 1. Prior to further analysis, singleton OTUs and samples with low sequencing depth were removed less than 10, reads. Chao1, PD whole tree, Shannon, Observed species and Simpson reciprocal metrics were used to assess alpha diversity within-sample diversity , while beta diversity between sample diversity comparison was assessed with weighted and unweighted UniFrac distance matrices 46 , 47 and presented with principal coordinates analysis PCoA.
The robustness of the identified clusters was investigated using jackknifing randomly resampling sequences without replacement. A Spearman coefficient close to 1 signifies a highly positive correlation between immune mediators and the distance matrices; a value close to 0 signifies no association; and a value approaching -1 signifies a highly negative correlation.
The quantification of soluble immune factors was performed using a recently described platform that is based on a magnetic bead multiplex immunoassay Luminex, Bio-Plex, BIO-RAD Laboratories, Milano, Italy , which simultaneously detects 48 analytes, including cytokines, chemokines and growth factors To normalize the results, the total protein concentrations of samples were determined using a Bradford assay Sigma-Aldrich, St. Louis, MO. Stata v.
The Kruskal-Wallis one-way analysis of variance was used for comparisons between groups. All participants provided written informed consent for the experiments involving human participants and gave permission to access their medical records. All experiments were performed in accordance with the Declaration of Helsinki. Srinivasan, S. The human vaginal bacterial biota and bacterial vaginosis. Brotman, R. Vaginal microbiome and sexually transmitted infections: an epidemiologic perspective.
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Hedges, S. Local and systemic cytokine levels in relation to changes in vaginal flora. Livengood, C. Bacterial vaginosis: an overview for Eschenbach, D. Bacterial vaginosis and anaerobes in obstetric-gynecologic infection.
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