1.
The Human Vulvar Microbiome: A Systematic Review.
Pagan, L, Ederveen, RAM, Huisman, BW, Schoones, JW, Zwittink, RD, Schuren, FHJ, Rissmann, R, Piek, JMJ, van Poelgeest, MIE
Microorganisms. 2021;9(12)
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Vaginal microbiome composition and its link with cancer is an emerging area in research. Imbalances in the vaginal microbiome could initiate carcinogenesis by altering immunity and metabolism and accelerating inflammation. This systematic review included ten studies and assessed the vulvar microbiome in premalignant vulvar disease and healthy vulvar skin. The healthy vulvar skin showed several bacterial taxa of Lactobacillus, Corynebacterium, Staphylococcus and Prevotella of intestinal, cutaneous and vaginal origin. L. crispatus and L. iners were dominant on the vulva of most healthy women. L. gasseri dominance was non-significantly associated with vestibulodynia. Menstruation did not alter the bacterial composition. Premenarchial Lichen sclerosus may have an association with microbial dysbiosis. Further robust studies are required to identify the vaginal microbial composition due to the high heterogeneity of the studies included, small sample size and methodological limitations. Healthcare professionals can utilise the data from this study to better understand how the vulvar microbiome influences disease aetiology and its importance as a target for therapy.
Abstract
The link between cancer and the microbiome is a fast-moving field in research. There is little knowledge on the microbiome in ((pre)malignant) conditions of the vulvar skin. This systematic review aims to provide an overview of the literature regarding the microbiome composition of the healthy vulvar skin and in (pre)malignant vulvar disease. This study was performed according to the PRISMA guidelines. A comprehensive, electronic search strategy was used to identify original research articles (updated September 2021). The inclusion criteria were articles using culture-independent methods for microbiome profiling of the vulvar region. Ten articles were included. The bacterial composition of the vulva consists of several genera including Lactobacillus, Corynebacterium, Staphylococcus and Prevotella, suggesting that the vulvar microbiome composition shows similarities with the corresponding vaginal milieu. However, the vulvar microbiome generally displayed higher diversity with commensals of cutaneous and fecal origin. This is the first systematic review that investigates the relationship between microbiome and vulvar (pre)malignant disease. There are limited data and the level of evidence is low with limitations in study size, population diversity and methodology. Nevertheless, the vulvar microbiome represents a promising field for exploring potential links for disease etiology and targets for therapy.
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The skin microbiome in psoriatic disease: A systematic review and critical appraisal.
Yerushalmi, M, Elalouf, O, Anderson, M, Chandran, V
Journal of translational autoimmunity. 2019;2:100009
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Psoriasis is a common inflammatory skin disease that results in patches of dry, scaly skin that can be itchy or sore. Psoriatic arthritis is an inflammatory arthritis that affects up to 30% of psoriasis patients. The role of skin bacteria (the skin microbiome) is not well understood. This systematic review summarised the literature on the microbiome in psoriatic disease. The researchers looked at nine studies: seven on psoriasis only, and two studies comparing the microbiome characteristics between psoriasis and psoriatic arthritis. Compared to healthy controls, the skin of psoriasis patients demonstrated a decreased species diversity, higher relative abundances of Firmicutes, and lower relative abundances of Actinobacteria. Less conclusive were genus-level results, which demonstrated trends towards increased Streptococcus, Staphylococcus, and Corynebacterium, and decreased Propionibacterium in the skin of psoriasis patients versus healthy controls. However, the studies’ designs and methodologies varied, and therefore the researchers concluded that further research into the role of the skin microbiome in psoriatic disease is needed.
Abstract
BACKGROUND Psoriasis affects 1-3% of the Canadian population. Psoriatic arthritis (PsA), the most common comorbidity of psoriasis, affects up to 30% of psoriasis patients. The skin microbiome is hypothesized to play a role in the pathogenesis of psoriatic disease (PsD-psoriasis and PsA). OBJECTIVE To summarize the current state of literature on the skin microbiome in PsD. METHODS A systematic review was performed using searches in Ovid, Medline, Embase, Medline Epub Ahead of Print and In-Process & Other Non-Indexed Citations, and Cochrane Central Register of Controlled Trials (CENTRAL). Search was limited to humans and English language, with no limits for date or publication type. RESULTS Of 4,032 citations identified, 9 studies met inclusion criteria (7 on psoriasis only and 2 studies compared the microbiome characteristics between psoriasis and PsA). Compared to healthy controls, lesions demonstrated a decreased alpha diversity, higher relative abundances of Firmicutes, and lower relative abundances of Actinobacteria. Less conclusive were genus-level results, which nonetheless demonstrated trends towards increased Streptococcus, Staphylococcus, and Corynebacterium and decreased Propionibacterium in lesions vs. control. LIMITATIONS Study designs were heterogeneous, including sampling technique and exclusion criteria. CONCLUSIONS Phyla- and selected genus-level characteristic of the psoriatic microbiome are presented; further research is warranted.
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Disruption of maternal gut microbiota during gestation alters offspring microbiota and immunity.
Nyangahu, DD, Lennard, KS, Brown, BP, Darby, MG, Wendoh, JM, Havyarimana, E, Smith, P, Butcher, J, Stintzi, A, Mulder, N, et al
Microbiome. 2018;6(1):124
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The gut microbiota is key for immune development, especially during a critical window in infancy, and it has been shown that maternal diet before, during and after pregnancy influences infant metabolism and gut microbiota. The aim of this study was to assess the effects of maternal antibiotics administration during gestation and nursing on offspring gut microbiota and immunity. Pregnant mice, dams, received oral vancomycin in drinking water 5 days prior to give birth (gestation group), 14 days after delivery (nursing group) or 5 days prior to delivery and throughout nursing (gestation plus nursing group), while control mice received no vancomycin. Adaptive immunity and gut microbiota in dams and pups were analysed at various times after delivery. This study showed that antibiotic alteration of maternal gut microbiota during both pregnancy and nursing results in changes in the adaptive immunity in offspring. The authors conclude these findings are important as they provide insight into the mechanism by which maternal exposures during pregnancy may impact infant health, therefore identifying potential targets for intervention.
Abstract
BACKGROUND Early life microbiota is an important determinant of immune and metabolic development and may have lasting consequences. The maternal gut microbiota during pregnancy or breastfeeding is important for defining infant gut microbiota. We hypothesized that maternal gut microbiota during pregnancy and breastfeeding is a critical determinant of infant immunity. To test this, pregnant BALB/c dams were fed vancomycin for 5 days prior to delivery (gestation; Mg), 14 days postpartum during nursing (Mn), or during gestation and nursing (Mgn), or no vancomycin (Mc). We analyzed adaptive immunity and gut microbiota in dams and pups at various times after delivery. RESULTS In addition to direct alterations to maternal gut microbial composition, pup gut microbiota displayed lower α-diversity and distinct community clusters according to timing of maternal vancomycin. Vancomycin was undetectable in maternal and offspring sera, therefore the observed changes in the microbiota of stomach contents (as a proxy for breastmilk) and pup gut signify an indirect mechanism through which maternal intestinal microbiota influences extra-intestinal and neonatal commensal colonization. These effects on microbiota influenced both maternal and offspring immunity. Maternal immunity was altered, as demonstrated by significantly higher levels of both total IgG and IgM in Mgn and Mn breastmilk when compared to Mc. In pups, lymphocyte numbers in the spleens of Pg and Pn were significantly increased compared to Pc. This increase in cellularity was in part attributable to elevated numbers of both CD4+ T cells and B cells, most notable Follicular B cells. CONCLUSION Our results indicate that perturbations to maternal gut microbiota dictate neonatal adaptive immunity.