Introduction

By Michelle van Slobbe

Human microbiota

The human microbiota is the collective name that has been given for all the microorganisms that live on or in the human body. This microbiota is comprised of viruses, archaea, protists, fungi, and bacteria[1]. In the last years, there has been increasingly more attention for the human microbiome. The microbiome has been thought to have a lot of influence on human health. For example, the content of the microbiome is related to obesity according to Alang and Kelly[2]. Yamamoto et al.[3] claim that cancer is also associated with the microbiome. In addition to that Schmidt et al.[4] concluded from their research that the microbiome influences mental health. The human microbiota changes in composition during human life and is influenced by several factors that can change its composition. For example, according to Conlon et al. smoking, stress and diet can change the microbial composition.[5]

The composition of the human microbiome changes during life

Source: https://www.researchgate.net/figure/230736332_fig1_Figure-1-Human-microbiota-onset-and-shaping-through-life-stages-and-perturbations-The

Do you know why one person is always bitten be a mosquito, whilst another person is never bitten? To find out the answer, you should definitely watch this Ted-Talk! In this Ted-Talk, Rob Knight tells you a lot of interesting facts about the microbiota. It gives a good overview and also repeats some of the information that was already discussed in this introduction.

The female microbiome

Human papillomavirus
From: https://www.std.uw.edu/go/
pathogen-based/hpv/core-concept/all

Because the topic microbiome is so extensive, our blog will zoom in on the female microbiome firstly, and then on the female microbiome and its relation to pregnancy.  A lot of research concerning the female microbiome has already been conducted in the last couple of years. Miltra et al.[6] for example investigated the influence of the vaginal microbiota on the progression of human papillomavirus and cervical intraepithelial neoplasia and came to the conclusion that the microbiota very likely plays a role in the progression of these disorders. It was also concluded that further research is necessary to prove these with certainty and to find out which specific species are protective to developing an infection with human papillomavirus and cervical intraepithelial neoplasia. 

Lactobacillus
From:http://www.uaz.edu.mx/histo/pathology
/ed/ch_9b/path/00001446.htm

Other research that was done in the field of the female microbiome was conducted by Ann E. Stapleton[7].  Her article describes that the female microbiota can play a big role in the pathogenesis of a urinary tract infection. The bacterium Lactobacillus species is normally protective for the development of a urinary tract infection, but when this bacterium is lost the infection can occur more easily. 

Human immunodeficiency virus
From:https://www.avert.org/professionals/hiv-science/overview

Another very interesting research on this subject has been carried out by Vitali et al.[8] They reviewed the factors that influence the susceptibility of women to get infected with HIV. The conclusion they made regarding the effect of the female microbiome on HIV susceptibility was that hormones regulate the microbiome, which results in higher or lower susceptibility. When the estrogen levels are high, there will be a lot of Lactobacillus species present in the vaginal microbiome, which results in reduced genital inflammation. The result of this is reduced susceptibility to HIV. On the other hand, high progesterone levels will lead to increased genital inflammation and therefore higher susceptibility to HIV.

Although these subjects regarding the female microbiota are all very interesting, our group was most fascinated by another interaction between the microbiota and pregnancy. According to Josef Neu[9], the microbiome can influence the course of the pregnancy of women. He discusses multiple mechanisms that explain the relation between the microbiome and preterm labour. It is, for example, suggested that higher microbial loads in the amniotic fluid lead to inflammation, which will lead to preterm labour. This is just one of the mechanisms that are explained, but the mechanisms have in common that the microbes found in the foetus and uterus very likely have its source in the intestine of the mother. More about this subject can be read in the scientific background. More about the mechanisms that are behind the interaction of the microbiome and preterm labour can be read in changing the microbiome. Because the microbiome is interacted with preterm labour, this could mean that by influencing the microbiome, preterm labour could be prevented. A lot of research has been done into this subject, of which some will be discussed in innovative therapies.

Prematurely born child in incubator
From: https://www.mijnantonius.nl/uw-baby-op-de-couveuse-unit

References introduction:

[1] Arkan MC. The intricate connection between diet, microbiota, and cancer: A jigsaw puzzle. Semin Immunol. 2017 Sep 1. pii: S1044-5323(17)30023-4.

[2] Alang N, Kelly CR. Weight Gain After Fecal Microbiota Transplantation. Open Forum of Infectious Diseases 2015; 2.

[3] Yamamoto ML, Maier I, Dang AT, Berry D, Liu J, Ruegger PM, Yang JI, Soto PA, Presley LL, Reliene R, Westbrook AM, Wei B, Loy A, Chang C, Braun J, Borneman J, Schiestl RH. Intestinal bacteria modify lymphoma incidence and latency by affecting systemic inflammatory state, oxidative stress, and leukocyte genotoxicity. Cancer Res. 2013 Jul 15;73(14):4222-32.

[4] Schmidt K, Cowen PJ, Harmer CJ, Tzortzis G, Errington S, Burnet PWJ. Prebiotic intake reduces the waking cortisol response and alters emotional bias in healthy volunteers. Psychopharmacology 2015; 232(10): 1793–1801.

[5] Conlon MA, Bird AR. The impact of diet and lifestyle on gut microbiota and human health. Nutrients. 2015; 7(1): 17–44.

[6] Mitra A, MacIntyre DA, Marchesi JR, Lee YS, Bennett PR, Kyrgiou M. The vaginal microbiota, human papillomavirus infection and cervical intraepithelial neoplasia: what do we know and where are we going next? Microbiome 2016; 4:58.

[7] Stapleron AE. The vaginal microbiota and urinary tract infection. Microbiol Spectr. 2016 ;4(6).

[8] Vitali D, Wessels JM, Kaushic C. Role of sex hormones and the vaginal microbiome in susceptibility and mucosal immunity to HIV-1 in the female genital tract. AIDS Res Ther. 2017;14(1):39.

[9] Neu J. The microbiome during pregnancy and early postnatal life. Seminars in Fetal & Neonatal Medicine 2016; 21: 373-379.