Microbial Profiling of Amniotic Fluid, Umbilical Blood and Placenta of the Foaling Mare.
Abstract: The presence of a microbiome/microbiota in the placenta is hotly debated. In previous studies, the presence of bacteria in equine amniotic fluid and umbilical blood was independent of foal health. The objective of the present study was to determine if the same bacteria are present in the equine placenta as in amniotic fluid and umbilical blood. Samples were obtained from 24 parturient mares and foals. Placental bacterial DNA was extracted, and the microbiome was identified using 16S rRNA sequencing. All amniotic fluid samples contained some polymorphonucleocytes; bacteria were isolated from four samples. Aerobic or anaerobic growth was found in 18 and 3 umbilical blood samples, respectively. Serum amyloid A was <5 mg/L in all 24 samples, total WBC varied between 2900 and 10,700/µL, and fibrinogen varied between 0 and 5.16 g/L. In jugular blood, serum amyloid A was <5 mg/L in all 24 foals, total white blood count was 3200 to 8100/µL, and fibrinogen was 0.44 to 4.42 g/L. The diversity of bacterial microbiota was similar in all placental regions at the phylum level but differed at the genus level; the most abundant phyla were Proteobacteria (42-46.26%) and Actinobacteria (26.91-29.96%). In conclusion, bacteria were found in the fetal compartments and placenta of healthy equine pregnancies; however, we can neither prove nor disprove the hypothesis that the placenta has its own microbiome.
Publication Date: 2023-06-18 PubMed ID: 37370539PubMed Central: PMC10295694DOI: 10.3390/ani13122029Google Scholar: Lookup
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Summary
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This research investigates whether bacteria are present in the placenta of healthy pregnant horses, refuting the common belief that the uterus is a sterile environment. After analyzing samples obtained from multiple foaling mares, the study finds bacterial presence in the amniotic fluid, umbilical blood and placenta. However, it could not solidify the argument for a placenta-specific microbiome.
Objective
- The goal of this research was to explore the presence of bacteria in the equine placenta, amniotic fluid, and umbilical blood.
- Through this investigation, the researchers hoped to either affirm or refute the hypothesis of a placenta-specific microbiome.
Methodology
- Samples were collected from 24 mares that were giving birth along with their foals.
- These samples included placental substances, umbilical blood, and amniotic fluid.
- Bacterial DNA was extracted from these placental samples, and its composition was identified via 16S rRNA sequencing – a popular method for studying bacterial diversity.
Findings
- The majority of amniotic fluid samples contained some polymorphonucleocytes, a type of white blood cell, and bacteria were found in a portion of these samples.
- Different growth rates, both aerobic and anaerobic were observed in the umbilical blood samples.
- The concentration of Serum Amyloid A, a common biomarker for inflammation, was less than 5mg/L in all 24 samples.
- The White Blood Cell (WBC) count varied widely amongst the samples, between 2900 and 10,700/µL.
- Fibrinogen, a blood clotting factor, also varied in concentration from 0 to 5.16 g/L in the samples.
- In the samples from the jugular blood of the foal, Serum Amyloid A was less than 5mg/L in all of them, the white blood cell count was 3200 to 8100/µL, and fibrinogen was 0.44 to 4.42 g/L.
- The bacterial composition in all placental regions showed similar diversity at the phylum level but differed at the genus level.
- The most abundant phyla were Proteobacteria (42-46.26%) and Actinobacteria (26.91-29.96%).
Conclusion
- Bacteria were indeed discovered in the fetal compartments and placenta in healthy equine pregnancies, which confirms that the uterus is not sterile.
- However, the study remains inconclusive about a unique placenta-specific microbiome due to its inability to provide definitive evidence supporting or discrediting this hypothesis.
Cite This Article
APA
Hemberg E, Niazi A, Guo Y, Debnár VJ, Vincze B, Morrell JM, Kútvölgyi G.
(2023).
Microbial Profiling of Amniotic Fluid, Umbilical Blood and Placenta of the Foaling Mare.
Animals (Basel), 13(12), 2029.
https://doi.org/10.3390/ani13122029 Publication
Researcher Affiliations
- Herrgården Hjortkvarn, SE-697 93 Hjortkvarn, Sweden.
- SLU-Global Bioinformatics Centre, Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences (SLU), SE-750 07 Uppsala, Sweden.
- National Bioinformatics Infrastructure Sweden (NBIS), Science for Life Laboratory, Uppsala University, SE-752 36 Uppsala, Sweden.
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences (SLU), SE-750 07 Uppsala, Sweden.
- Department of Precision Livestock Farming and Animal Biotechnics, Institute of Animal Sciences, Kaposvár Campus, Hungarian University of Agriculture and Life Sciences, H-2100 Gödöllő, Hungary.
- Department of Obstetrics and Food Animal Medicine, University of Veterinary Medicine, H-1078 Budapest, Hungary.
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences (SLU), SE-750 07 Uppsala, Sweden.
- Department of Precision Livestock Farming and Animal Biotechnics, Institute of Animal Sciences, Kaposvár Campus, Hungarian University of Agriculture and Life Sciences, H-2100 Gödöllő, Hungary.
Grant Funding
- NA / Marie Claire Cronstedt Stiftelsen, Sweden
Conflict of Interest Statement
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
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Citations
This article has been cited 2 times.- Herzog F, Crissman KR, Beckers KF, Zhou G, Liu CC, Sones JL. Lactobacillus Genus Complex Probiotic-Induced Changes on the Equine Clitoral Microbiome. Vet Sci 2025 Mar 3;12(3).
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