Monday, June 13, 2016

Menopause and the changing Vaginal Microbiome

With the increase in average life expectancy of women worldwide, it is estimated that 1.2 billion women will be menopausal or postmenopausal by the year 2030. About 85% of whom will experience at-least one menopausal symptom in lifetime. In US alone about 40 to 50 million women are estimated to suffer from vasomotor symptoms.
A recent review published in the forthcoming issue of Maturitas, The European menopause Journal  compares the  changes in vaginal microbiome with approaching menopause, the role of hormone replacement therapy in vaginal bacterial community  and role of probiotics in reinstating the homeostasis.

The vaginal microbiome plays an important role in women’s life, right from puberty to menopause. The diversity, abundance and composition of the microbial species in vagina varies dramatically. One of the original NIH-funded Human MicrobiomeProject (HMP) targeted sites for characterization of the microbiota was the vagina.

The relationship between the vaginal microbiome and menopause occurs predominantly through estrogen. During reproductive years, production of lactic acid and hydrogen peroxide by lactobacilli help maintain a strong barrier to pathogenic bacteria by maintaining a vaginal pH of 3.8 to 4.5. 

During the perimenopause women experience hormonal fluctuations, with decline in estrogen levels leading to a progressive decrease in acid-producing bacteria and pH rises >4.6 – this disrupts the vaginal micro-habitat and can lead to problems such as bacterial vaginosis. Normal flora has a dominance of various Lactobacilli, while in bacterial vaginosis (BV) microbiota is dominated by Gardnerella vaginalis and includes a number of anaerobic organisms.

In reproductive age women the microbial species in vagina can be grouped in five consistent groupings, referred to by Ravel et al as community state types (CSTs). Out of the 5 CSTs, the first four have higher proportion of Lactobacillus species whereas the fifth (CST IV) has lower proportions of Lactobacillus spp. and higher proportions of anaerobic organisms including Mobiluncus spp., and Atopobium vaginae.

As women progress towards premenopause and menopause, the composition of the VMB undergo significant change and play an important role in vulvovaginal atrophy. Postmenopausal hypoestrogenism causes a cascade of events that starts with thinning of the vaginal epithelium, leading to a smaller contribution of glycogen and higher alkaline pH that inhibits the growth of Lactobacillus.

Rebecca Brotman is an epidemiologist and infectious disease expert by training has worked and researched extensively on Vaginal Microbiome and its role in reproductive tract infection through various stages of women’s life. She is interested in intervention in VMB in context of meeting many of the challenges of premeopausal and menopausal life. 
  
In a study by Brotman R.M et al significant association was found between vaginal bacterial composition with menopause stage and signs of vaginal atrophy. A distinctive community state type CST IV-A was identified which was highly associated with signs of Vulvo Vagianl Atrophy (VVA) and was predominant in post-menopausal women. CST IV-A is a low Lactobacillus state and is known by a higher abundance of genera including Anaerococcus, Peptoniphilus and Prevotella, which could be playing a pivotal role in the clinical presentation of VVA.

It was also seen that compared to women with no VVA, the odds of CST of women with atrophy being classified as CST IV-A was 25 times more than being labellled as CST I.

This study provides a valuable insight into further research and studies to modulate and restore VMB homeostasis to understand and treat VVA in postmenopausal women.

It is well known that estrogen therapy is effective for the treatment of VVA and concomitantly, hormonal replacement increases the abundance of vaginal Lactobacillus species. Oral and vaginal probiotics holds considerable promise as a therapeutic modality for future in restoring the vaginal microbiome.  However additional trials are required before bacterial therapeutics can find its way into treatment armament species.

Several small RCTs have shown the effect of combination of ultra-low-dose vaginal estriol 0.03 mg in combination with viable Lactobacillus acidophilus to treat vaginal atrophy is superior to placebo. But, larger studies and meta-analysis are still awaited.

To date, a 2 strain combination of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 have proved to be the most effective at restoring and maintaining a normal vaginal microbiota.

Science has yet not solved all the interactions between body and the microbiome. It is so complex that it will take many more years to understand the implications of this symbiosis and devising effective therapeutics.


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2 comments:

  1. A lot of changes take place in the mind and body of the women who reach the age of menopause. One of the harmful effects of this age is mild to major hair loss. How to reverse hair loss due to menopause?

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