Vaginal microbiota differences associated with pelvic organ prolapse risk during late gestation in commercial sows

In vitro biomechanical properties of porcine perineal tissues to better understand human perineal tears during delivery

INTRODUCTION

Data concerning the mechanical properties of the perineum during delivery are very limited. In vivo experiments raise ethical issues. The aim of the study was to describe some of the biomechanical properties of each perineal tissue layer collected from sows in order to better understand perineal tears during childbirth.

MATERIAL AND METHODS

Samples of each perineal tissue layer were obtained from the skin, the vagina, the external anal sphincter (EAS), the internal anal sphincter (IAS), and the anal mucosa of fresh dead sows. They were tested in quasi-static uniaxial tension using the testing machine Mach-1®. Tests were performed at a displacement velocity of 0.1 mm·s-1. Stress-strain curves of each perineal tissue layer before the first damage for each sow were obtained and modeled using a hyperelastic Yeoh model described by three coefficients: C1, C2, and C3. Pearson correlation coefficients were calculated to measure the correlation between the C1 hyperelastic coefficient and the duration between the first microfailure and the complete rupture for each perineal tissue layer. Pearson correlation was computed between C1 and the number of microfailures before complete rupture for each tissue.

RESULTS

Ten samples of each perineal tissue layer were analyzed. Mean values of C1 and corresponding standard deviations were 46 ± 15, 165 ± 60, 27 ± 10, 19 ± 13, 145 ± 28 kPa for the perineal skin, the vagina, the EAS, the IAS, and the anal mucosa, respectively. According to this same sample order, the first microfailure in the population of 10 sows appeared at an average of 54%, 27%, 70%, 131%, and 22% of strain. A correlation was found between C1 hyperelastic coefficient and the duration between the first microfailure and the complete rupture (r = 0.7, p = 0.02) or the number of microfailures before complete rupture only for the vagina (r = 0.7, p = 0.02).

CONCLUSIONS

In this population of fresh dead sow's perineum, the vagina and the anal mucosa were the stiffest tissues. The IAS and EAS were more extensible and less stiff. A significantly positive correlation was found between C1 and the duration between the first microfailure and the complete rupture of the vagina, and the duration between the first microfailure and the complete rupture of the vagina.

Current practice in animal models for pelvic floor dysfunction

INTRODUCTION AND HYPOTHESIS

The objective was to explore the current practice of using animal models for female pelvic floor dysfunction (PFD).

METHODS

By applying PFD and animal models as the keywords, we made a computerized search using PubMed, Ovid-Medline and Ovid-Embase from 2000 to 2022. The publications on the construction and application of animal models for PFD were included, and the results are presented in narrative text.

RESULTS

Studies on PFD primarily use rodents, large quadrupeds, and nonhuman primates (NHPs). NHPs are closest to humans in anatomy and biomechanics of the pelvic floor, followed by large quadrupeds and rodents. Rodents are more suitable for studying molecular mechanism, histopathology of PFD, and mesh immune rejection. Large quadrupeds are adaptable to the study of pelvic floor biomechanics and the development of new surgical instruments for PFD. NHPs are suitable for studying the occurrence and pathogenesis of pelvic organ prolapse. Among modeling methods, violent destruction of pelvic floor muscles, regulation of hormone levels, and denervation were used to simulate the occurrence of PFD. Gene knockout can be used to study both the pathogenesis of PFD and the efficacy of treatments. Other methods such as abdominal wall defect, vaginal defect, and in vitro organ bath system are more frequently used to observe wound healing after surgery and to verify the efficacy of treatments.

CONCLUSIONS

The rat is currently the most applicable animal type for numerous modeling methods. Vaginal dilation is the most widely used modeling method for research on the pathogenesis, pathological changes, and treatment of PFD.

Reproductive Microbiomes in Domestic Livestock: Insights Utilizing 16S rRNA Gene Amplicon Community Sequencing

Advancements in 16S rRNA gene amplicon community sequencing have vastly expanded our understanding of the reproductive microbiome and its role in fertility. In humans, Lactobacillus is the overwhelmingly dominant bacteria within reproductive tissues and is known to be commensal and an indicator of fertility in women and men. It is also known that Lactobacillus is not as largely abundant in the reproductive tissues of domestic livestock species. Thus, the objective of this review is to summarize the research to date on both female and male reproductive microbiomes in domestic livestock species (i.e., dairy cattle, beef cattle, swine, small ruminants, and horses). Having a comprehensive understanding of reproductive microbiota and its role in modulating physiological functions will aid in the development of management and therapeutic strategies to improve reproductive efficiency.

Identification of the genetic basis of sow pelvic organ prolapse

Introduction: Pelvic organ prolapse (POP) is one contributor to recent increases in sow mortality that have been observed in some populations and environments, leading to financial losses and welfare concerns. Methods: With inconsistent previous reports, the objective here was to investigate the role of genetics on susceptibility to POP, using data on 30,429 purebred sows, of which 14,186 were genotyped (25K), collected from 2012 to 2022 in two US multiplier farms with a high POP incidence of 7.1% among culled and dead sows and ranging from 2% to 4% of all sows present by parity. Given the low incidence of POP for parities 1 and >6, only data from parities 2 to 6 were retained for analyses. Genetic analyses were conducted both across parities, using cull data (culled for POP versus another reason), and by parity, using farrowing data. (culled for POP versus culled for another reason or not culled). Results and Discussion: Estimates of heritability from univariate logit models on the underlying scale were 0.35 ± 0.02 for the across-parity analysis and ranged from 0.41 ± 0.03 in parity 2 to 0.15 ± 0.07 in parity 6 for the by-parity analyses. Estimates of genetic correlations of POP between parities based on bivariate linear models indicated a similar genetic basis of POP across parities but less similar with increasing distance between parities. Genome wide association analyses revealed six 1 Mb windows that explained more than 1% of the genetic variance in the across-parity data. Most regions were confirmed in several by-parity analyses. Functional analyses of the identified genomic regions showed a potential role of several genes on chromosomes 1, 3, 7, 10, 12, and 14 in susceptibility to POP, including the Estrogen Receptor gene. Gene set enrichment analyses showed that genomic regions that explained more variation for POP were enriched for several terms from custom transcriptome and gene ontology libraries. Conclusion: The influence of genetics on susceptibility to POP in this population and environment was confirmed and several candidate genes and biological processes were identified that can be targeted to better understand and mitigate the incidence of POP.