Identifying microbiome-based changes and biomarkers prior to disease development in mother and child, with a focus on gestational diabetes mellitus: protocol for the DANish Maternal and Offspring Microbiome (DANMOM) cohort study.

INTRODUCTION: The human gut microbiota is associated with gestational diabetes mellitus (GDM), which imposes a risk of developing long-term health problems for mother and child. Most studies on GDM and microbiota have been cross-sectional, which makes it difficult to make any conclusions on causality. Furthermore, it is important to assess if a dysbiotic microbiota is passed from the mother to the child, and then being at risk of developing metabolic health problems later in life. The DANish Maternal and Offspring Microbiome study aims to identify gut microbiota-related factors involved in metabolic dysfunction in women with GDM and their offspring. Importantly, the study design allows for early detection of biological changes associated with later development of metabolic disease. This could provide us with unique tools to support early diagnosis or implement preventative measures. METHODS AND ANALYSIS: Pregnant women are included in the study after the 11-14 weeks' prenatal ultrasound scan and followed throughout pregnancy with enrolment of the offspring at birth. 202 women and 112 children have been included from North Denmark Regional Hospital and Aalborg University Hospital in Denmark. Mother and child are followed until the children reach the age of 5 years. From the mother, we collect faeces, urine, blood, saliva, vaginal fluid and breast milk samples, in addition to faeces and a blood sample from the child. Microbiota composition in biological samples will be analysed using 16S rRNA gene sequencing and compared with demographic and clinical data from medical charts, registers and questionnaires. Sample and data collection will continue until July 2028. ETHICS AND DISSEMINATION: The study protocol has been approved by the North Denmark Region Committee on Health Research Ethics (N20190007). Written informed consent is obtained from all participants prior to study participation. Study results will be published in international peer-reviewed journals and presented at international conferences. The results will also be presented to the funders of the study and study participants.

A comparison of the breast milk microbiota from women diagnosed with gestational diabetes mellitus and women without gestational diabetes mellitus.

BACKGROUND: Human breast milk (HBM) is a contributing factor in modulating the infant's gut microbiota, as it contains bacteria that are directly transferred to the infant during breastfeeding. It has been shown that children of women diagnosed with gestational diabetes mellitus (GDM) have a different gut microbiota compared to children of women without GDM. Our hypothesis is therefore that women with GDM have a different HBM microbiota, which may influence the metabolic function and capacity of the child later in life. The aim of this study was to investigate whether women with GDM have a different breast milk microbiota 1-3 weeks postpartum compared to women without GDM. METHODS: In this case-control study, a total of 45 women were included: 18 women with GDM and 27 women without GDM. A milk sample was collected from each participant 1 to 3 weeks postpartum and the bacterial composition was examined by 16 S rRNA gene sequencing targeting the V4 region. RESULTS: High relative abundances of Streptococcus and Staphylococcus were present in samples from both women with and without GDM. No difference could be seen in either alpha diversity, beta diversity, or specific taxa between groups. CONCLUSION: Our results did not support the existence of a GDM-associated breast milk microbiota at 1-3 weeks postpartum. Further research is needed to fully understand the development of the gut microbiota of infants born to mothers with GDM.

Children and adolescents with attention deficit hyperactivity disorder and autism spectrum disorder share distinct microbiota compositions.

An association has been suggested between altered gut microbiota, and attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD), respectively. Thus, we analyzed the gut microbiota composition in children and adolescents with or without these disorders and evaluated the systemic effects of these bacteria. We recruited study participants diagnosed with ADHD, ASD, and comorbid ADHD/ASD, while the control groups consisted both of siblings and non-related children. The gut microbiota was analyzed by 16S rRNA gene sequencing of the V4 region, while the concentration of lipopolysaccharide-binding protein (LBP), cytokines, and other signaling molecules were measured in plasma. Importantly the gut microbiota compositions of cases with ADHD and ASD were highly similar for both alpha- and beta-diversity while differing from that of non-related controls. Furthermore, a subset of ADHD and ASD cases had an increased LBP concentration compared to non-affected children, which was positively correlated with interleukin (IL)-8, 12, and 13. These observations indicate disruption of the intestinal barrier and immune dysregulation among the subset of children with ADHD or ASD.

Characteristics of the gut microbiome in women with gestational diabetes mellitus: A systematic review.

BACKGROUND: The incidence of women developing gestational diabetes mellitus (GDM) is increasing, which is associated with an increased risk of type 2 diabetes mellitus (T2DM) for both mother and child. Gut microbiota dysbiosis may contribute to the pathogenesis of both GDM and the accompanying risk of T2DM. Thus, a better understanding of the microbial communities associated with GDM could offer a potential target for intervention and treatment in the future. Therefore, we performed a systematic review to investigate if the GDM women have a distinct gut microbiota composition compared to non-GDM women. METHODS: We identified 21 studies in a systematic literature search of Embase and PubMed up to February 24, 2021. Data on demographics, methodology and identified microbial metrics were extracted. The quality of each study was assessed according to the Newcastle-Ottawa Scale. RESULTS: Sixteen of the studies did find a GDM-associated gut microbiota, although no consistency could be seen. Only Collinsella and Blautia showed a tendency to be increased in GDM women, whereas the remaining genera were significantly different in opposing directions. CONCLUSION: Although most of the studies found an association between GDM and gut microbiota dysbiosis, no overall GDM-specific gut microbiota could be identified. All studies in the second trimester found a difference between GDM and non-GDM women, indicating that dysbiosis is present at the time of diagnosis. Nevertheless, it is still unclear when the dysbiosis develops, as no consensus could be seen between the studies investigating the gut microbiota in the first trimester of pregnancy. However, studies varied widely concerning methodology and study design, which might explain the highly heterogeneous gut microbiota compositions between studies. Therefore, future studies need to include multiple time points and consider possible confounding factors such as ethnicity, pre-pregnancy body mass index, and GDM treatment.

The Prevalence and Clinical Implications of Rectal SARS-CoV-2 Shedding in Danish COVID-19 Patients and the General Population.

Background: SARS-CoV-2 has resulted in a global pandemic since its outbreak in Wuhan, 2019. Virus transmission primarily occurs through close contact, respiratory droplets, and aerosol particles. However, since SARS-CoV-2 has been detected in fecal and rectal samples from infected individuals, the fecal-oral route has been suggested as another potential route of transmission. This study aimed to investigate the prevalence and clinical implications of rectal SARS-CoV-2 shedding in Danish COVID-19 patients. Methods: Hospitalized and non-hospitalized adults and children who were recently tested with a pharyngeal COVID-19 test, were included in the study. A rectal swab was collected from all participants. Hospitalized adults and COVID-19 positive children were followed with both pharyngeal and rectal swabs until two consecutive negative results were obtained. RT-qPCR targeting the envelope gene was used to detect SARS-CoV-2 in the samples. Demographic, medical, and biochemical information was obtained through questionnaires and medical records. Results: Twenty-eight of 52 (53.8%) COVID-19 positive adults and children were positive for SARS-CoV-2 in rectal swabs. Seven of the rectal positive participants were followed for more than 6 days. Two of these (28.6%) continued to test positive in their rectal swabs for up to 29 days after the pharyngeal swabs had turned negative. Hospitalized rectal positive and rectal negative adults were comparable regarding demographic, medical, and biochemical information. Furthermore, no difference was observed in the severity of the disease among the two groups. Conclusions: We provided evidence of rectal SARS-CoV-2 shedding in Danish COVID-19 patients. The clinical importance of rectal SARS-CoV-2 shedding appears to be minimal.