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Home / Equine Research Bank / Equine Vet J / Characterisation of the testicular transcriptome in stallion...
Equine veterinary journal2022; 55(2); 239-252; doi: 10.1111/evj.13588

Characterisation of the testicular transcriptome in stallions with age-related testicular degeneration.

Abstract: Age-related testicular degeneration can be defined as the progressive deterioration of the testis that typically occurs in middle-aged or older males and that leads to diminished testicular function and subfertility. In the equine breeding industry, genetically valuable males maintain their value as breeding animals well into old age. Because testicular degeneration is common in middle-aged and older stallions, the disease often has a significant negative impact on a stallion's breeding career and leads to economic losses in the horse breeding industry. Objective: Because testicular degeneration is a tissue autologous disease in the horse, the objective of this study was to use whole-transcriptome sequencing to compare the testicular transcriptomes of normal, fertile stallions to those of stallions affected by age-related testicular degeneration in order to better understand the pathophysiology of the disease. Methods: Cross sectional. Methods: Testicular tissue samples from clinical castrations or euthanasia were collected from normal healthy (n = 3) or older subfertile (n = 4) stallions. Samples were processed and sequenced on an Illumina HiSeq™ 2000 Sequencing System. Bioinformatic analysis of the data was performed in R/RStudio, and the transcriptomes were compared between the two groups. Genes were considered to be differentially expressed between healthy and diseased tissue if they demonstrated at least a ±1.5× fold change difference and had a false discovery rate-adjusted P value <0.05. Gene ontology analysis was performed using Ingenuity® IPA. Results: Analyses of differential expression of individual genes, as well as computer-based gene ontology analysis, identified upregulation of cytokine-mediated inflammatory pathways in testes from stallions affected with testicular degeneration. This upregulation of inflammation was associated with upregulation of cell survival pathways, inhibition of apoptotic pathways and increases in collagen formation. Conclusions: There are unavoidable confounding factors (e.g. differences in breed, management, environment, age) that could create non disease-related genetic variation between our normal and affected samples. In addition, there are practical limitations to applying computer-based gene ontology analysis to equine samples. Gene ontology software relies on published information (mostly non-equine), and some biological processes (e.g. apoptosis and inflammation) are more commonly studied than others and so are over-represented in the literature and therefore more likely to be identified by computer algorithms. Caution should be taken when interpreting the data, as alterations in gene expression can be the cause of disease processes or can be the result of disease processes. Conclusions: These results suggest that chronic, low-grade inflammation may be involved in the pathophysiology of age-related testicular degeneration in stallions.
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Publication Date: 2022-06-21 PubMed ID: 35569039DOI: 10.1111/evj.13588Google Scholar: Lookup
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Summary

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This research investigates the effects of age-related testicular degeneration in stallions by analyzing the changes in the genes manifested in the testes, possibly impacting their reproductive capabilities.

Objective and Methodology

  • The study aims to attain a deeper understanding of the causes and effects of age-related testicular degeneration in stallions. Researchers employed whole-transcriptome sequencing to discern the differences in gene expression between healthy, fertile stallions and those affected by the condition.
  • For the comparative analysis, testicular tissue samples from 3 healthy stallions and 4 older subfertile stallions were processed and sequenced using an Illumina HiSeq™ 2000 Sequencing System.
  • Data acquired from the sequencing was then processed and analyzed using a programming language, R/RStudio. Differentially expressed genes, or genes with significant variations in their expression between healthy and diseased stallions, were selected based on a minimum 1.5 fold change difference and a false discovery rate-adjusted P value less than 0.05.
  • Ingenuity® IPA, a gene ontology software, was then used to assign meaning to the large lists of genes generated in the whole-transcriptome sequencing.

Results

  • Computer-based gene ontology analysis and the comparison of individual genes revealed that cytokine-mediated inflammatory pathways were significantly elevated or upregulated in testes of stallions with age-related testicular degeneration.
  • The increased inflammation was found to be associated with enhanced cell survival pathways, inhibited cell death or apoptotic pathways, and an increment in collagen formation.
  • The results imply that chronic, low-grade inflammation could be a factor contributing to age-related testicular degeneration in stallions.

Limitations and Conclusions

  • It is crucial to note that the study could be influenced by unavoidable confounding factors such as differences in breed, management practices, environment, and age between the normal and affected samples.
  • Also, practical limitations come into play when using computer-based gene ontology analysis on equine samples, as the software relies significantly on published non-equine information, and some biological processes are studied more often than others, leading to them being over-represented in the literature.
  • Lastly, the study highlights the need for careful interpretation of such data as changes in gene expression can either be the cause or the result of disease processes.

Cite This Article

APA
Woodward E, Schlingmann K, Tobias J, Turner R. (2022). Characterisation of the testicular transcriptome in stallions with age-related testicular degeneration. Equine Vet J, 55(2), 239-252. https://doi.org/10.1111/evj.13588

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 55
Issue: 2
Pages: 239-252

Researcher Affiliations

Woodward, Elizabeth
  • Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Schlingmann, Karen
  • Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA.
Tobias, John
  • Penn Genome Analysis Core, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Turner, Regina
  • Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA.

MeSH Terms

  • Horses / genetics
  • Animals
  • Male
  • Testis / physiology
  • Transcriptome
  • Cross-Sectional Studies

Grant Funding

  • Grayson-Jockey Club Research Foundation

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Citations

This article has been cited 3 times.
  1. Njoga UJ, Anya KO, Ekere SO, Amune FN, Eze LU, Awachie ME, Ojimba LC, Ochiogu IS, Njoga EO. Ameliorative effects of vitamin C and garlic (Allium sativum) on nifedipine-induced reproductive dysfunction in a male albino rat model. Front Vet Sci 2025;12:1725725.
    doi: 10.3389/fvets.2025.1725725pubmed: 41695207google scholar: lookup
  2. Choi MR, Chang HJ, Heo JH, Yum SH, Jo E, Kim M, Lee SR. Expression Profiling of Coding and Noncoding RNAs in the Endometrium of Patients with Endometriosis. Int J Mol Sci 2024 Oct 1;25(19).
    doi: 10.3390/ijms251910581pubmed: 39408909google scholar: lookup
  3. Waqas MS, Arroyo E, Tibary A. Diagnostic Approach to Equine Testicular Disorders. Vet Sci 2024 May 29;11(6).
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