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Equine veterinary journal2026; doi: 10.1002/evj.70216

Altered gene expression in the liver and small intestine of horses with equine neuroaxonal dystrophy.

Abstract: Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is the second most common diagnosis of spinal ataxia in horses in the United States. The disease develops due to a combination of vitamin E deficiency and an unknown genetic risk factor(s), and there currently is no effective treatment. Objective: We performed transcriptomic profiling of the liver and small intestine of horses with and without eNAD/EDM, as both tissues are the main locations for absorption, metabolism, and delivery of vitamin E to the nervous system. Methods: Case-control exploratory study. Methods: Postmortem-confirmed cases of eNAD/EDM were compared to horses that had eNAD/EDM excluded at necropsy and were euthanised for either non-neurologic disease or for cervical vertebral compressive myelopathy (CVCM), which were included due to the logistical challenge of obtaining control horses that have undergone a full neuropathologic review. RNA was isolated from frozen liver (eNAD/EDM n = 34, non-eNAD/EDM n = 27) and small intestinal (eNAD/EDM n = 18, non-eNAD/EDM n = 18) samples. Gene expression was compared between groups using a linear model, adjusting for age, breed, and RNA integrity score. Results: No genes were differentially expressed at p <0.05 in either tissue between eNAD/EDM and non-eNAD/EDM horses. However, one of the top genes, NPC1L1, was upregulated in the liver of horses with eNAD/EDM (logFC = 0.93, p < 0.05). In the small intestine, 747 genes were differentially expressed (p <0.05), including two genes that were markedly downregulated in both tissues. These genes have high sequence homology to LGALS9. Conclusions: Non-neurologic control numbers were limited. Tissues were collected at the time of euthanasia and therefore may not capture biological processes that were occurring at the time the neurological damage developed. Conclusions: Processes related to both cholesterol transport and autophagy may be altered in horses with eNAD/EDM. Two new candidate genes for eNAD/EDM, NPC1L1 and LGALS9, were identified for further investigation.
© 2026 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2026-07-16 PubMed ID: 42461371DOI: 10.1002/evj.70216Google Scholar: Lookup
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Summary

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Altered gene expression was studied in the liver and small intestine of horses affected by equine neuroaxonal dystrophy (eNAD/EDM) to identify potential biological processes and genes involved in the disease related to vitamin E metabolism.

Background and Disease Context

  • Equine neuroaxonal dystrophy (eNAD/EDM) is a neurological disorder causing spinal ataxia in horses, commonly diagnosed in the United States.
  • The disease is linked to a combination of vitamin E deficiency and unknown genetic risk factors.
  • There is currently no effective treatment for eNAD/EDM.
  • The liver and small intestine play key roles in vitamin E absorption, metabolism, and distribution to the nervous system, making them focus tissues for studying eNAD/EDM-related gene expression changes.

Objective of the Study

  • To perform transcriptomic profiling (comprehensive gene expression analysis) of the liver and small intestine in horses with confirmed eNAD/EDM compared to horses without the disease.
  • To identify differences in gene expression that could provide insight into the biological changes in affected horses and implicate novel candidate genes linked to eNAD/EDM.

Study Design and Methods

  • The study was a case-control exploratory design using postmortem tissue samples.
  • Cases were horses with neuropathology-confirmed eNAD/EDM.
  • Controls were horses with either no neurological disease or cervical vertebral compressive myelopathy (CVCM), included due to challenges in obtaining fully neuropathologically reviewed control samples.
  • Samples:
    • Liver samples: 34 eNAD/EDM horses, 27 controls
    • Small intestine samples: 18 eNAD/EDM horses, 18 controls
  • RNA was extracted from frozen tissues and analyzed for gene expression differences using linear models.
  • Models adjusted for age, breed, and RNA integrity to account for confounding factors.

Key Results

  • No genes reached statistical significance for differential expression (p<0.05) in liver tissue after adjustments.
  • One notable gene, NPC1L1 (Niemann-Pick C1-like 1), showed upregulation in the liver of eNAD/EDM horses, suggesting altered cholesterol transport or vitamin E absorption mechanisms.
  • In small intestine samples, 747 genes showed differential expression at p<0.05, indicating more pronounced transcriptional changes in this tissue.
  • Among these, two genes homologous to LGALS9 (galectin-9) were significantly downregulated in both liver and small intestine; these genes are implicated in autophagy and immune regulation.

Interpretation and Biological Implications

  • Alterations in cholesterol transport pathways may be involved in eNAD/EDM pathogenesis, possibly linked to vitamin E metabolism since vitamin E is fat-soluble and associated with lipid transport mechanisms.
  • Downregulation of LGALS9-like genes suggests potential disruptions in autophagy or cellular turnover processes, which could impact nervous system health and susceptibility to neurodegeneration.
  • Changes were more evident in the small intestine, a key tissue in nutrient absorption, highlighting the role of intestinal function in the disease.

Limitations

  • Limited number of non-neurologic control horses, which may affect the generalizability of the findings.
  • Tissue sampling was conducted postmortem at euthanasia, possibly missing dynamic gene expression changes during the disease’s active phase.

Conclusions and Future Directions

  • The study identified NPC1L1 and LGALS9 as new candidate genes related to eNAD/EDM, warranting further functional investigation.
  • Findings suggest that alterations in cholesterol transport and autophagy pathways might contribute to disease development.
  • Further research is necessary to explore the mechanisms by which these genes influence disease progression and to develop potential therapeutic approaches targeting vitamin E metabolism and its related pathways.

Cite This Article

APA
Ryan S, Durbin-Johnson B, Woolard K, Miller AD, Finno CJ. (2026). Altered gene expression in the liver and small intestine of horses with equine neuroaxonal dystrophy. Equine Vet J. https://doi.org/10.1002/evj.70216

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Ryan, Stephanie
  • Department of Population Health and Reproduction, University of California Davis, Davis, California, USA.
Durbin-Johnson, Blythe
  • Bioinformatics Core Facility, Genome Center, University of California Davis, Davis, California, USA.
Woolard, Kevin
  • Department of Pathology, Microbiology and Immunology, University of California Davis, Davis, California, USA.
Miller, Andrew D
  • Department of Population Medicine and Diagnostic Sciences, Section of Anatomic Pathology, College of Veterinary Medicine, Cornell University, New York, USA.
Finno, Carrie J
  • Department of Population Health and Reproduction, University of California Davis, Davis, California, USA.

Grant Funding

  • D24EQ-056 / Morris Animal Foundation
  • 24-04 / UC Davis Center for Equine Health
  • American Quarter Horse Foundation

References

This article includes 57 references
  1. Finno CJ, Johnson AL. Equine neuroaxonal dystrophy and degenerative myeloencephalopathy.. Vet Clin N Am Equine Pract 2022;38:213–224.
  2. Finno CJ, Estell KE, Katzman S, Winfield L, Rendahl A, Textor J. Blood and cerebrospinal fluid α‐tocopherol and selenium concentrations in neonatal foals with neuroaxonal dystrophy.. J Vet Intern Med 2015;29:1667–1675.
  3. Finno CJ, Famula T, Aleman M, Higgins RJ, Madigan JE, Bannasch DL. Pedigree analysis and exclusion of alpha‐tocopherol transfer protein (TTPA) as a candidate gene for neuroaxonal dystrophy in the American Quarter Horse.. J Vet Intern Med 2013;27:177–185.
  4. Aleman M, Finno CJ, Higgins RJ, Puschner B, Gericota B, Gohil K. Evaluation of epidemiological, clinical, and pathological features of neuroaxonal dystrophy in Quarter Horses.. J Am Vet Med Assoc 2011;239:823–833.
  5. Finno CJ, Valberg SJ, Shivers J, D'Almeida E, Armién AG. Evidence of the primary afferent tracts undergoing neurodegeneration in horses with equine degenerative Myeloencephalopathy based on Calretinin Immunohistochemical localization.. Vet Pathol 2016;53:77–86.
  6. Finno CJ, Bordbari MH, Valberg SJ, Lee D, Herron J, Hines K. Transcriptome profiling of equine vitamin E deficient neuroaxonal dystrophy identifies upregulation of liver X receptor target genes.. Free Radical Biology and Medicine 2016;101:261–271.
  7. Traber MG, Head B. Vitamin E: how much is enough, too much and why!. Free Radical Biol Med 2021;177:212–225.
  8. Azzi A, Atkinson J, Ozer NK, Manor D, Wallert M, Galli F. Vitamin E nomenclature.. Free Radical Biol Med 2025;234:277–282.
  9. Hales EN, Habib H, Favro G, Katzman S, Sakai RR, Marquardt S. Increased α‐tocopherol metabolism in horses with equine neuroaxonal dystrophy.. J Vet Intern Med 2021;35:2473–2485.
  10. Finno CJ, Higgins RJ, Aleman M, Ofri R, Hollingsworth SR, Bannasch DL. Equine degenerative myeloencephalopathy in Lusitano horses.. J Vet Intern Med 2011;25:1439–1446.
  11. Woodie B, Johnson AL, Grant B. Cervical vertebral stenotic myelopathy.. Vet Clin N Am Equine Practice 2022;38:225–248.
  12. Peng S, Dahlgren AR, Donnelly CG, Hales EN, Petersen JL, Bellone RR. Functional annotation of the animal genomes: an integrated annotation resource for the horse.. PLoS Genet 2023;19:e1010468.
  13. HTStream. https://github.com/s4hts/HTStream?tab=readme-ov-file.
  14. Dobin A, Davis CA, Schlesinger F, Drenkow J, Zaleski C, Jha S. STAR: ultrafast universal RNA‐seq aligner.. Bioinformatics 2013;29:15–21.
  15. Karlsson M, Zhang C, Méar L, Zhong W, Digre A, Katona B. A single–cell type transcriptomics map of human tissues.. Sci Adv 2021;7:eabh2169.
  16. Elmentaite R, Kumasaka N, Roberts K, Fleming A, Dann E, King HW. Cells of the human intestinal tract mapped across space and time. Nature 2021;597:250–255.
  17. Knutson MD. Iron transport proteins: gateways of cellular and systemic iron homeostasis. J Biol Chem 2017;292:12735–12743.
  18. Chen Y, Lun ATL, Smyth GK. From reads to genes to pathways: differential expression analysis of RNA‐Seq experiments using Rsubread and the edgeR quasi‐likelihood pipeline. F1000Res 2016;5:1438.
  19. Szklarczyk D, Nastou K, Koutrouli M, Kirsch R, Mehryary F, Hachilif R. The STRING database in 2025: protein networks with directionality of regulation. Nucleic Acids Res 2025;53:D730–D737.
  20. Ridley AJ. Rho GTPases and actin dynamics in membrane protrusions and vesicle trafficking. Trends Cell Biol 2006;16:522–529.
  21. Wang B, Tontonoz P. Liver X receptors in lipid signalling and membrane homeostasis. Nat Rev Endocrinol 2018;14:452–463.
  22. Kaltner H, Raschta A‐S, Manning JC, Gabius H‐J. Copy‐number variation of functional galectin genes: studying animal galectin‐7 (p53‐induced gene 1 in man) and tandem‐repeat‐type galectins‐4 and ‐9. Glycobiology 2013;23:1152–1163.
  23. Burns EN, Finno CJ. Equine degenerative myeloencephalopathy: prevalence, impact, and management. Vet Med 2018;9:63–67.
  24. Hacquebard M, Carpentier YA. Vitamin E: absorption, plasma transport and cell uptake. Curr Opin Clin Nutr Metab Care 2005;8:133–138.
  25. Ma Y, Peng S, Donnelly CG, Ghosh S, Miller AD, Woolard K. Genetic polymorphisms in vitamin E transport genes as determinants for risk of equine neuroaxonal dystrophy. J Vet Intern Med 2024;38:417–423.
  26. Jia L, Betters JL, Yu L. Niemann‐pick C1‐like 1 (NPC1L1) protein in intestinal and hepatic cholesterol transport. Annu Rev Physiol 2011;73:239–259.
  27. Kamishikiryo J, Haraguchi M, Nakashima S, Tasaka Y, Narahara H, Sugihara N. N‐terminal domain of the cholesterol transporter Niemann–Pick C1‐like 1 (NPC1L1) is essential for α‐tocopherol transport. Biochem Biophys Res Commun 2017;486:476–480.
  28. Narushima K, Takada T, Yamanashi Y, Suzuki H. Niemann‐pick C1‐like 1 mediates α‐tocopherol transport. Mol Pharmacol 2008;74:42–49.
  29. Blythe LL, Craig AM, Lassen ED, Rowe KE, Appell LH. Serially determined plasma α‐tocopherol concentrations and results of the oral vitamin E absorption test in clinically normal horses and in horses with degenerative myeloencephalopathy. Am J Vet Res 1991;52:908–911.
  30. National Research Council. Nutrient requirements of horses: sixth revised edition. Washington, DC: The National Academies Press; 2007.
    doi: 10.17226/11653google scholar: lookup
  31. Reboul E, Goncalves A, Comera C, Bott R, Nowicki M, Landrier J. Vitamin D intestinal absorption is not a simple passive diffusion: evidences for involvement of cholesterol transporters. Mol Nutr Food Res 2011;55:691–702.
  32. Lucot KL, Dickinson PJ, Finno CJ, Mansour TA, Letko A, Minor KM. A missense mutation in the vacuolar protein sorting 11 (VPS11) gene is associated with neuroaxonal dystrophy in Rottweiler dogs. G3 2018;8:2773–2780.
  33. Fleming A, Bourdenx M, Fujimaki M, Karabiyik C, Krause GJ, Lopez A. The different autophagy degradation pathways and neurodegeneration. Neuron 2022;110:935–966.
  34. Feng H, Yao W, Zhang Y, Liu Y, Liu B, Zhou J. LGALS9B stabilizes EEF1D protein and activates the PI3K/AKT signaling pathway to promote gastric cancer occurrence and metastasis. Oncogene 2025;44:652–664.
  35. Munson MJ, O'Driscoll G, Silva AM, Lázaro‐Ibáñez E, Gallud A, Wilson JT. A high‐throughput Galectin‐9 imaging assay for quantifying nanoparticle uptake, endosomal escape and functional RNA delivery. Commun Biol 2021;4:211.
  36. Jia J, Bissa B, Brecht L, Allers L, Choi SW, Gu Y. AMPK, a regulator of metabolism and autophagy, is activated by lysosomal damage via a novel galectin‐directed ubiquitin signal transduction system. Mol Cell 2020;77:951–969.e9.
  37. Sudhakar JN, Lu H‐H, Chiang H‐Y, Suen C‐S, Hwang M‐J, Wu S‐Y. Lumenal Galectin‐9‐Lamp2 interaction regulates lysosome and autophagy to prevent pathogenesis in the intestine and pancreas. Nat Commun 2020;11:4286.
  38. Sané AT, Sinnett D, Delvin E, Bendayan M, Marcil V, Ménard D. Localization and role of NPC1L1 in cholesterol absorption in human intestine. J Lipid Res 2006;47:2112–2120.
  39. Ulatowski L, Parker R, Davidson C, Yanjanin N, Kelley TJ, Corey D. Altered vitamin E status in Niemann‐Pick type C disease. J Lipid Res 2011;52:1400–1410.
  40. Qian J, Morley S, Wilson K, Nava P, Atkinson J, Manor D. Intracellular trafficking of vitamin E in hepatocytes: the role of tocopherol transfer protein. J Lipid Res 2005;46:2072–2082.
  41. O'Brien CE, Younger SH, Jan LY, Jan YN. The GARP complex prevents sterol accumulation at the trans‐Golgi network during dendrite remodeling. J Cell Biol 2023;222:e202112108.
  42. Hetmańczyk‐Sawicka K, Iwanicka‐Nowicka R, Fogtman A, Cieśla J, Włodarski P, Żyżyńska‐Granica B. Changes in global gene expression indicate disordered autophagy, apoptosis and inflammatory processes and downregulation of cytoskeletal signalling and neuronal development in patients with Niemann–Pick C disease. Neurogenetics 2020;21:105–119.
  43. Wu H, Feng K, Zhang C, Zhang H, Zhang J, Hua Y. Metformin attenuates atherosclerosis and plaque vulnerability by upregulating KLF2‐mediated autophagy in apoE−/− mice. Biochem Biophys Res Commun 2021;557:334–341.
  44. Huang Y, Wang YF, Ruan XZ, Lau CW, Wang L, Huang Y. The role of KLF2 in regulating hepatic lipogenesis and blood cholesterol homeostasis via the SCAP/SREBP pathway. J Lipid Res 2024;65:100472.
  45. Oyarce‐Pezoa S, Rucatti GG, Muñoz‐Carvajal F, Sanhueza N, Gomez W, Espinoza S. The autophagy protein Def8 is altered in Alzheimer's disease and Aβ42‐expressing Drosophila brains. Sci Rep 2023;13:17137.
  46. Tian Y, Lu J, Hao X, Li H, Zhang G, Liu X. FTH1 inhibits Ferroptosis through ferritinophagy in the 6‐OHDA model of Parkinson's disease. Neurotherapeutics 2020;17:1796–1812.
  47. Zhang L, Zhang M, Huang J, Huang J, Zhang Y, Zhang Y. Klf9 is essential for cardiac mitochondrial homeostasis. Nat Cardiovasc Res 2024;3:1318–1336.
  48. Kim YJ, Lee S‐G, Park SY, Jeon SM, Kim SI, Kim KT. Ubiquitin regulatory X (UBX) domain‐containing protein 6 is essential for autophagy induction and inflammation control in macrophages. Cell Mol Immunol 2024;21:1441–1458.
  49. Yalvac ME, Amornvit J, Braganza C, Chen L, Hussain S‐RA, Shontz KM. Impaired regeneration in calpain‐3 null muscle is associated with perturbations in mTORC1 signaling and defective mitochondrial biogenesis. Skeletal Muscle 2017;7:27.
  50. Saha S, Mandal A, Ranjan A, Ghosh DK. Membrane tension sensing formin‐binding protein 1 is a neuronal nutrient stress‐responsive Golgiphagy receptor. Metabolism 2025;162:156040.
  51. Chrisman CL, Cork LC, Gamble DA. Neuroaxonal dystrophy of Rottweiler dogs. J Am Vet Med Assoc 1984;184:464–467.
  52. Cork LC, Troncoso JC, Price DL, Stanley EF, Griffin JW. Canine neuroaxonal dystrophy. J Neuropathol Exp Neurol 1983;42:286–296.
  53. Nixon RA, Rubinsztein DC. Mechanisms of autophagy–lysosome dysfunction in neurodegenerative diseases. Nat Rev Mol Cell Biol 2024;25:926–946.
  54. Roca‐Agujetas V, Barbero‐Camps E, De Dios C, Podlesniy P, Abadin X, Morales A. Cholesterol alters mitophagy by impairing optineurin recruitment and lysosomal clearance in Alzheimer's disease. Mol Neurodegener 2021;16:15.
  55. Appu AP, Bagh MB, Plavelil N, Mondal A, Sadhukhan T, Singh SP. Niemann Pick C1 mistargeting disrupts lysosomal cholesterol homeostasis contributing to neurodegeneration in a Batten disease model. Sci Adv 2025;11(19):eadr5703.
  56. Fukui K, Masuda A, Hosono A, Suwabe R, Yamashita K, Shinkai T. Changes in microtubule‐related proteins and autophagy in long‐term vitamin E‐deficient mice. Free Radic Res 2014;48:649–658.
  57. Maharjan Y, Dutta RK, Son J, Wei X, Park C, Kwon HM. Intracellular cholesterol transport inhibition impairs autophagy flux by decreasing autophagosome–lysosome fusion. Cell Commun Signal 2022;20:189.

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