O-128 Intra-cycle alterations of the uterine microbiota in patients with recurrent miscarriage or recurrent implantation failure and healthy controls

Study question

Uterine microbiota: are there differences within three major time points of the menstrual cycle in healthy controls, recurrent miscarriage (RM) and recurrent implantation failure (RIF) patients?

Summary answer

Compared to controls, RM and RIF patients showed an altered uterine microbiota throughout the menstrual cycle, with a lower dominance of lactobacilli.

What is known already

In contrast to the former notion of a sterile womb, bacterial colonization in the uterus and the placenta has been demonstrated. Studies showed that Lactobacillus-dominated endometrial microbiota correlate with reproductive success. Moreover, the presence of non-Lactobacillus-dominated microbiota, especially with detection of Gardnerella and Streptococcus in the endometrial fluid, seems to be associated with lower implantation-, ongoing pregnancy- and live birth-rates. However, intra-cycle variations in healthy women as well as possible alterations in patients with RM or RIF remain unknown.

Study design, size, duration

In total, n = 20 RM patients (≥ 3 consecutive miscarriages), n = 20 RIF patients (≥3 fresh or frozen embryo transfers with negative serum hCG, good quality embryos) and n = 10 healthy controls (no pregnancy) were included in this study. All patients had a 28 day menstrual cycle. During follicular, ovulatory and luteal-phase, after a thorough cleaning of the cervix, a flexible catheter was introduced into the uterine cavity and a uterine flushing with 1ml of NaCl was performed.

Participants/materials, setting, methods

Bacterial DNA was extracted using a QIAamp DNA kit (Qiagen) in combination with a PrecellysR24 homogenizer (Peqlab, Erlangen, Germany) according to the manufacturer’s instructions. The V3-V4 region of the bacterial 16S rRNA gene was amplified. Samples were pooled in equimolar ratios and progressed to pyrosequencing using an Illumina MiSeq se-quencer with MiSeq Kit V2 (250 bp paired-end). Analysis of 16S rRNA data, including alpha- and beta-diversity, were calculated using the phyloseq package in R.

Main results and the role of chance

For the Shannon index (species richness and evenness) a significant decrease during the ovulation period was shown in the control group, indicating a more uniform microbiota (p < 0.05). This loss of diversity was not shown in RIF and RM patients. Overall, we could observe a higher similarity in taxonomic distribution in RM compared to the RIF patients. Longitudinal dynamics included increases in Firmicutes (CTRL and RM only) and a concomitant loss of Proteobacteria. Notably, significant amounts of bacteroides were only detected in the RIF patients. Actinobacteria were more frequent in both, RM and RIF as compared to controls.

Limitations, reasons for caution

To minimize the impact of a potential contamination, we performed pre-experiments with paired samples both from the vaginal fornix and the endometrial cavum and could show a significant difference in overall microbiome configuration. However, the route of sample can still be prone to contamination.

Wider implications of the findings

For the first time, we were able to show cycle-dependent alterations in the endometrial microbiome. These findings underline the role of an altered endometrial microbiome as a cause for RM and RIF and can contribute to the future establishment of therapeutic strategies in cases of a dysbalanced microbiome.

Trial registration number

Drks00020803

Microbial Butyrate Synthesis Indicates Therapeutic Efficacy of Azathioprine in IBD Patients

BACKGROUND AND AIMS

The microbial ecosystem seems to be an important player for therapeutic intervenption in inflammatory bowel disease [IBD]. We assessed longitudinal microbiome changes in IBD patients undergoing therapy with either azathioprine [AZA] or anti-tumour necrosis factor [anti-TNF] antibodies. We predicted the metabolic microbial community exchange and linked it to clinical outcome.

METHODS

Faecal and blood samples were collected from 65 IBD patients at baseline and after 12 and 30 weeks on therapy. Clinical remission was defined as Crohn's Disease Activity Index [CDAI] < 150 in Crohn´s disease [CD], partial Mayo score <2 in ulcerative colitis [UC], and faecal calprotectin values <150 µg/g and C-reactive protein <5 mg/dl. 16S rRNA amplicon sequencing was performed. To predict microbial community metabolic processes, we constructed multispecies genome-scale metabolic network models.

RESULTS

Paired Bray-Curtis distance between baseline and follow-up time points was significantly different for UC patients treated with anti-TNF antibodies. Longitudinal changes in taxa composition at phylum level showed a significant decrease of Proteobacteria and an increase of Bacteroidetes in CD patients responding to both therapies. At family level, Lactobacilli were associated with persistent disease and Bacteroides abundance with remission in CD. In-silico simulations of microbial metabolite exchange predicted a 1.7-fold higher butyrate production capacity of patients in remission compared with patients without remission [p = 0.041]. In this model, the difference in butyrate production between patients in remission and patients without remission was most pronounced in the CD group treated with AZA [p = 0.008].

CONCLUSIONS

In-silico simulation identifies microbial butyrate synthesis predictive of therapeutic efficacy in IBD.