Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney disease

IntroductionFeline CKD is associated with an increase in the pro-fibrotic enzyme, transglutaminase 2 (TG2), in the kidney tubulointerstitium. Hypoxia is pivotal factor for the development of CKD, irrespective of its origin. In cats, tubulointerstitial sclerosis develops without significant glomerula...

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Main Authors: A. C. Sánchez-Lara, M. Maamra, J. L. Haylor
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-07-01
Series:Frontiers in Veterinary Science
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Online Access:https://www.frontiersin.org/articles/10.3389/fvets.2025.1520917/full
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author A. C. Sánchez-Lara
M. Maamra
J. L. Haylor
author_facet A. C. Sánchez-Lara
M. Maamra
J. L. Haylor
author_sort A. C. Sánchez-Lara
collection DOAJ
description IntroductionFeline CKD is associated with an increase in the pro-fibrotic enzyme, transglutaminase 2 (TG2), in the kidney tubulointerstitium. Hypoxia is pivotal factor for the development of CKD, irrespective of its origin. In cats, tubulointerstitial sclerosis develops without significant glomerular involvement, similar to a rodent model of renal warm ischaemia (RWI).MethodsSprague-Dawley rats underwent 60-min renal hilar clamping followed by right nephrectomy with/without intrarenal infusion of a transglutaminase inhibitor (TGI). Renal fibrosis was assessed by immunofluorescence of collagens after 28-days. Extracellular-TG-enzyme activity (eTGact) and extracellular-TG2 protein (eTG2) were measured in both the glomerular and the tubulointerstitial spaces.HypothesisRenal Warm Ischemia (RWI) will induce fibrotic changes and activation of the transglutaminase pathway in both the tubulointerstitial and glomerular compartments, and that treatment with a transglutaminase inhibitor (TGI) will mitigate these effects.ResultsRats subjected to RWI showed a significant elevation in tubulointerstitial collagen I (1.8-fold), III (4.3-fold), IV (5.5-fold), eTGact (2-fold) and eTG2 (1.9-fold), together with an increase in serum creatinine (2.7-fold). TG inhibition significantly reduced tubulointerstitial collagen I, III, IV, eTGact and eTG2 by 100%, 57%, 90%, 89%, and 91%, respectively, and decreased creatinine levels by 70%. However, RWI in the glomerulus showed a significant reduction in the TG pathway and collagen I and IV.DiscussionOur findings support a causal link between TG2 and tubulointerstitial fibrosis in rats following RWI. In contrast, the glomerular TG-pathway was suppressed, suggesting a protective mechanism in response to RWI, which may help to explain the lack of glomerular involvement in feline CKD. This rodent model of RWI may be analogous to feline CKD, enabling extrapolation of findings from rodent RWI models to understand renal insult in cats.
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spelling doaj-art-3d121b5daef64e2d925c04ba4b1d83ea2025-08-20T03:25:12ZengFrontiers Media S.A.Frontiers in Veterinary Science2297-17692025-07-011210.3389/fvets.2025.15209171520917Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney diseaseA. C. Sánchez-Lara0M. Maamra1J. L. Haylor2Department of Veterinary Medicine, School of Biological Sciences, Queen's Veterinary School Hospital, The University of Cambridge, Cambridge, United KingdomSchool of Chemical, Materials and Biological Engineering, University of Sheffield, Sheffield, United KingdomDepartment of Infection, Immunity and Cardiovascular Disease, Academic Nephrology Unit, Medical School, University of Sheffield, Sheffield, United KingdomIntroductionFeline CKD is associated with an increase in the pro-fibrotic enzyme, transglutaminase 2 (TG2), in the kidney tubulointerstitium. Hypoxia is pivotal factor for the development of CKD, irrespective of its origin. In cats, tubulointerstitial sclerosis develops without significant glomerular involvement, similar to a rodent model of renal warm ischaemia (RWI).MethodsSprague-Dawley rats underwent 60-min renal hilar clamping followed by right nephrectomy with/without intrarenal infusion of a transglutaminase inhibitor (TGI). Renal fibrosis was assessed by immunofluorescence of collagens after 28-days. Extracellular-TG-enzyme activity (eTGact) and extracellular-TG2 protein (eTG2) were measured in both the glomerular and the tubulointerstitial spaces.HypothesisRenal Warm Ischemia (RWI) will induce fibrotic changes and activation of the transglutaminase pathway in both the tubulointerstitial and glomerular compartments, and that treatment with a transglutaminase inhibitor (TGI) will mitigate these effects.ResultsRats subjected to RWI showed a significant elevation in tubulointerstitial collagen I (1.8-fold), III (4.3-fold), IV (5.5-fold), eTGact (2-fold) and eTG2 (1.9-fold), together with an increase in serum creatinine (2.7-fold). TG inhibition significantly reduced tubulointerstitial collagen I, III, IV, eTGact and eTG2 by 100%, 57%, 90%, 89%, and 91%, respectively, and decreased creatinine levels by 70%. However, RWI in the glomerulus showed a significant reduction in the TG pathway and collagen I and IV.DiscussionOur findings support a causal link between TG2 and tubulointerstitial fibrosis in rats following RWI. In contrast, the glomerular TG-pathway was suppressed, suggesting a protective mechanism in response to RWI, which may help to explain the lack of glomerular involvement in feline CKD. This rodent model of RWI may be analogous to feline CKD, enabling extrapolation of findings from rodent RWI models to understand renal insult in cats.https://www.frontiersin.org/articles/10.3389/fvets.2025.1520917/fullglomerular transglutaminasetubulointerstitial transglutaminasefeline chronic kidney diseaserenal warm ischemiatransglutaminase 2 (TG2)
spellingShingle A. C. Sánchez-Lara
M. Maamra
J. L. Haylor
Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney disease
Frontiers in Veterinary Science
glomerular transglutaminase
tubulointerstitial transglutaminase
feline chronic kidney disease
renal warm ischemia
transglutaminase 2 (TG2)
title Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney disease
title_full Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney disease
title_fullStr Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney disease
title_full_unstemmed Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney disease
title_short Reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia: implications for feline chronic kidney disease
title_sort reduced glomerular and elevated tubulointerstitial transglutaminase pathway and its inhibition in a rat model of renal warm ischemia implications for feline chronic kidney disease
topic glomerular transglutaminase
tubulointerstitial transglutaminase
feline chronic kidney disease
renal warm ischemia
transglutaminase 2 (TG2)
url https://www.frontiersin.org/articles/10.3389/fvets.2025.1520917/full
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AT mmaamra reducedglomerularandelevatedtubulointerstitialtransglutaminasepathwayanditsinhibitioninaratmodelofrenalwarmischemiaimplicationsforfelinechronickidneydisease
AT jlhaylor reducedglomerularandelevatedtubulointerstitialtransglutaminasepathwayanditsinhibitioninaratmodelofrenalwarmischemiaimplicationsforfelinechronickidneydisease