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Spencer S, Wheeler-Jones C, Elliott J. Hypoxia and chronic kidney disease: Possible mechanisms, therapeutic targets, and relevance to cats. Vet J 2021; 274:105714. [PMID: 34252550 DOI: 10.1016/j.tvjl.2021.105714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 07/01/2021] [Accepted: 07/06/2021] [Indexed: 10/20/2022]
Abstract
There is mounting evidence that kidney ischaemia/hypoxia plays an important role in feline chronic kidney disease (CKD) development and progression, as well as in human disease and laboratory animal models. Ischaemic acute kidney injury is widely accepted as a cause of CKD in people and data from laboratory species has identified some of the pathways underlying this continuum. Experimental kidney ischaemia in cats results in morphological changes, namely chronic tubulointerstitial inflammation, tubulointerstitial fibrosis, and tubular atrophy, akin to those observed in naturally-occurring CKD. Multiple situations are envisaged that could result in acute or chronic episodes of kidney hypoxia in cats, while risk factors identified in epidemiological studies provide further support that kidney hypoxia contributes to spontaneously occurring feline CKD. This review evaluates the evidence for the role of kidney ischaemia/hypoxia in feline CKD and the proposed mechanisms and consequences of kidney hypoxia. As no effective treatments exist that substantially slow or prevent feline CKD progression, there is a need for novel therapeutic strategies. Targeting kidney hypoxia is one such promising approach, with therapies including those that attenuate the hypoxia-inducible factor (HIF) pathway already being utilised in human CKD.
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Affiliation(s)
- Sarah Spencer
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK.
| | - Caroline Wheeler-Jones
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK
| | - Jonathan Elliott
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK
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2
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Lawson JS, Syme HM, Wheeler-Jones CPD, Elliott J. Investigation of the transforming growth factor-beta 1 signalling pathway as a possible link between hyperphosphataemia and renal fibrosis in feline chronic kidney disease. Vet J 2020; 267:105582. [PMID: 33375963 PMCID: PMC7814380 DOI: 10.1016/j.tvjl.2020.105582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/30/2020] [Accepted: 11/16/2020] [Indexed: 11/30/2022]
Abstract
Chronic kidney disease (CKD) is associated with development of hyperphosphataemia. Severity of renal fibrosis has been correlated with degree of hyperphosphataemia. Transforming growth factor-β1 (TGF-β1) is a major pro-fibrotic mediator in CKD. A phosphate restricted diet did not affect urinary active TGF-β1 excretion in cats. Increased extracellular phosphate had no pro-fibrotic effect on feline renal cells.
Chronic kidney disease (CKD) is common in geriatric cats, and is characterised in the majority of cases by tubulointerstitial inflammation and fibrosis. Hyperphosphataemia is a frequent complication of CKD and is independently associated with severity of renal fibrosis and disease progression. Transforming growth factor-beta 1 (TGF-β1) signalling is thought to be a convergent pathway which mediates the progression of renal fibrosis in CKD. The aims of this study were to explore the interaction between increased extracellular phosphate and the TGF-β1 signalling pathway by investigating: (a) the effect of a commercially available, phosphate-restricted, diet on urinary TGF-β1 excretion in cats with CKD; and (b) the role of increased extracellular phosphate in regulating proliferation, apoptosis, and expression of genes related to TGF-β1 signalling and extracellular matrix (ECM) production in feline proximal tubular epithelial cells (FPTEC) and cortical fibroblasts from cats with azotaemic CKD (CKD-FCF). The dietary intervention study revealed no effect of dietary phosphate restriction on urinary active TGF-β1 excretion after 4–8 weeks (P = 0.98), despite significantly decreasing serum phosphate (P < 0.001). There was no effect of increased growth media phosphate concentration (from 0.95 mM to 2 mM and 3.5 mM) on proliferation (P = 0.99) and apoptotic activity in FPTEC (P = 0.22), or expression of genes related to ECM production and the TGF-β1 signalling pathway in FPTEC and CKD-FCF (P > 0.05). These findings suggest the beneficial effects of dietary phosphate restriction on progression of feline CKD may not occur through modulation of renal TGF-β1 production, and do not support a direct pro-fibrotic effect of increased extracellular phosphate on feline renal cells.
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Affiliation(s)
- J S Lawson
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, UK.
| | - H M Syme
- Clinical Sciences and Services, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, UK
| | - C P D Wheeler-Jones
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, UK
| | - J Elliott
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, UK
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Spencer S, Wheeler‐Jones C, Elliott J. Aldosterone and the mineralocorticoid receptor in renal injury: A potential therapeutic target in feline chronic kidney disease. J Vet Pharmacol Ther 2020; 43:243-267. [PMID: 32128854 PMCID: PMC8614124 DOI: 10.1111/jvp.12848] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/20/2020] [Accepted: 02/09/2020] [Indexed: 12/24/2022]
Abstract
There is a growing body of experimental and clinical evidence supporting mineralocorticoid receptor (MR) activation as a powerful mediator of renal damage in laboratory animals and humans. Multiple pathophysiological mechanisms are proposed, with the strongest evidence supporting aldosterone-induced vasculopathy, exacerbation of oxidative stress and inflammation, and increased growth factor signalling promoting fibroblast proliferation and deranged extracellular matrix homeostasis. Further involvement of the MR is supported by extensive animal model experiments where MR antagonists (such as spironolactone and eplerenone) abrogate renal injury, including ischaemia-induced damage. Additionally, clinical trials have shown MR antagonists to be beneficial in human chronic kidney disease (CKD) in terms of reducing proteinuria and cardiovascular events, though current studies have not evaluated primary end points which allow conclusions to made about whether MR antagonists reduce mortality or slow CKD progression. Although differences between human and feline CKD exist, feline CKD shares many characteristics with human disease including tubulointerstitial fibrosis. This review evaluates the evidence for the role of the MR in renal injury and summarizes the literature concerning aldosterone in feline CKD. MR antagonists may represent a promising therapeutic strategy in feline CKD.
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Affiliation(s)
- Sarah Spencer
- Comparative Biomedical SciencesThe Royal Veterinary CollegeLondonUK
| | | | - Jonathan Elliott
- Comparative Biomedical SciencesThe Royal Veterinary CollegeLondonUK
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Kutlu T, Alcigir G. Comparison of renal lesions in cats and dogs using pathomorphological and ımmunohistochemical methods. Biotech Histochem 2018; 94:126-133. [PMID: 30328730 DOI: 10.1080/10520295.2018.1522670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We investigated the pathogenesis of chronic renal fibrosis in cats and dogs using immunohistochemistry. We used the avidin-biotin complex peroxidase (ABC-P) method with antibodies against transforming growth factor-β1, cytokeratin, E-cadherin, S100A4, alpha-smooth muscle actin, vimentin and nestin to determine whether tubule epithelial cells had undergone epithelial-mesenchymal transformation (EMT) that resulted in loss of epithelial cells and an increased number of mesenchymal cells. Although nephrosis was more common in dogs, nephritis was more common in cats; these pathologies developed in both kidneys. We found that EMT participated in the pathogenesis of renal fibrosis in both dogs and cats.
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Affiliation(s)
- Tuncer Kutlu
- a Faculty of Veterinary Medicine, Department of Pathology , Hatay Mustafa Kemal University , Hatay , Turkey
| | - Gunay Alcigir
- b Faculty of Veterinary Medicine, Department of Pathology , Ankara University , Ankara , Turkey
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Lawson JS, Syme HM, Wheeler-Jones CPD, Elliott J. Characterisation of feline renal cortical fibroblast cultures and their transcriptional response to transforming growth factor β1. BMC Vet Res 2018. [PMID: 29523136 PMCID: PMC5845201 DOI: 10.1186/s12917-018-1387-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Background Chronic kidney disease (CKD) is common in geriatric cats, and the most prevalent pathology is chronic tubulointerstitial inflammation and fibrosis. The cell type predominantly responsible for the production of extra-cellular matrix in renal fibrosis is the myofibroblast, and fibroblast to myofibroblast differentiation is probably a crucial event. The cytokine TGF-β1 is reportedly the most important regulator of myofibroblastic differentiation in other species. The aim of this study was to isolate and characterise renal fibroblasts from cadaverous kidney tissue of cats with and without CKD, and to investigate the transcriptional response to TGF-β1. Results Cortical fibroblast cultures were successfully established from the kidney tissue of cats with normal kidney function (FCF) and cats with chronic kidney disease (CKD-FCF). Both cell types expressed the mesenchymal markers vimentin, CD44 and CD29, and were negative for the epithelial marker cytokeratin, mesangial cell marker desmin and endothelial cell marker vWF. Only CKD-FCF expressed VCAM-1, a cell marker associated with inflammation. Incubation with TGF-β1 (0–10 ng/ml) induced a concentration dependent change in cell morphology, and upregulation of myofibroblast marker gene α-SMA expression alongside collagen 1α1, fibronectin, TGF-β1 and CTGF mRNA. These changes were blocked by the TGF-β1 receptor 1 antagonist SB431542 (5 μM). Conclusions FCF and CKD-FCF can be cultured via a simple method and represent a model for the investigation of the progression of fibrosis in feline CKD. The findings of this study suggest TGF-β1 may be involved in fibroblast-myofibroblast transition in feline CKD, as in other species.
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Affiliation(s)
- J S Lawson
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK.
| | - H M Syme
- Clinical Sciences and Services, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA, UK
| | - C P D Wheeler-Jones
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK
| | - J Elliott
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK
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Current Understanding of the Pathogenesis of Progressive Chronic Kidney Disease in Cats. Vet Clin North Am Small Anim Pract 2016; 46:1015-48. [PMID: 27461408 DOI: 10.1016/j.cvsm.2016.06.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In cats with chronic kidney disease (CKD), the most common histopathologic finding is tubulointerstitial inflammation and fibrosis. However, these changes reflect a nonspecific response of the kidney to any inciting injury. The risk of developing CKD is likely to reflect the composite effects of genetic predisposition, aging, and environmental and individual factors that affect renal function over the course of a cat's life. However, there is still little information available to determine exactly which individual risk factors predispose a cat to develop CKD. Although many cats diagnosed with CKD have stable disease for years, some cats show overtly progressive disease.
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Brown CA, Elliott J, Schmiedt CW, Brown SA. Chronic Kidney Disease in Aged Cats: Clinical Features, Morphology, and Proposed Pathogeneses. Vet Pathol 2016; 53:309-26. [PMID: 26869151 DOI: 10.1177/0300985815622975] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Chronic kidney disease (CKD) is the most common metabolic disease of domesticated cats, with most affected cats being geriatric (>12 years of age). The prevalence of CKD in cats exceeds that observed in dogs, and the frequency of the diagnosis of CKD in cats has increased in recent decades. Typical histologic features include interstitial inflammation, tubular atrophy, and fibrosis with secondary glomerulosclerosis. In contrast to people and dogs, primary glomerulopathies with marked proteinuria are remarkably rare findings in cats. Although a variety of primary renal diseases have been implicated, the disease is idiopathic in most cats. Tubulointerstitial changes, including fibrosis, are present in the early stages of feline CKD and become more severe in advanced disease. A variety of factors-including aging, ischemia, comorbid conditions, phosphorus overload, and routine vaccinations-have been implicated as factors that could contribute to the initiation of this disease in affected cats. Factors that are related to progression of established CKD, which occurs in some but not all cats, include dietary phosphorus intake, magnitude of proteinuria, and anemia. Renal fibrosis, a common histologic feature of aged feline kidneys, interferes with the normal relationship between peritubular capillaries and renal tubules. Experimentally, renal ischemia results in morphologic changes similar to those observed in spontaneous CKD. Renal hypoxia, perhaps episodic, may play a role in the initiation and progression of this disease.
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Affiliation(s)
- C A Brown
- Athens Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - J Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, UK
| | - C W Schmiedt
- Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - S A Brown
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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Zhang Q, Ji Y, Lv W, He T, Wang J. Protective effects of leflunomide on renal lesions in a rat model if diabetic nephropathy. Ren Fail 2015; 38:124-30. [DOI: 10.3109/0886022x.2015.1105024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Lawson J, Elliott J, Wheeler-Jones C, Syme H, Jepson R. Renal fibrosis in feline chronic kidney disease: known mediators and mechanisms of injury. Vet J 2014; 203:18-26. [PMID: 25475166 DOI: 10.1016/j.tvjl.2014.10.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 10/10/2014] [Accepted: 10/11/2014] [Indexed: 01/13/2023]
Abstract
Chronic kidney disease (CKD) is a common medical condition of ageing cats. In most cases the underlying aetiology is unknown, but the most frequently reported pathological diagnosis is renal tubulointerstitial fibrosis. Renal fibrosis, characterised by extensive accumulation of extra-cellular matrix within the interstitium, is thought to be the final common pathway for all kidney diseases and is the pathological lesion best correlated with function in both humans and cats. As a convergent pathway, renal fibrosis provides an ideal target for the treatment of CKD and knowledge of the underlying fibrotic process is essential for the future development of novel therapies. There are many mediators and mechanisms of renal fibrosis reported in the literature, of which only a few have been investigated in the cat. This article reviews the process of renal fibrosis and discusses the most commonly cited mediators and mechanisms of progressive renal injury, with particular focus on the potential significance to feline CKD.
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Affiliation(s)
- Jack Lawson
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK.
| | - Jonathan Elliott
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK
| | - Caroline Wheeler-Jones
- Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK
| | - Harriet Syme
- Clinical Sciences and Services, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK
| | - Rosanne Jepson
- Clinical Sciences and Services, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK
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10
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Abstract
PRACTICAL RELEVANCE Chronic kidney disease (CKD) is one of the most frequently encountered disorders in cats, having increased in prevalence in recent decades. Although the underlying cause is rarely identified, the common final outcome of feline CKD is tubulointerstitial fibrosis. Knowledge of CKD pathophysiology is necessary for optimal individualised patient management, especially with regard to diagnosis and treatment of extrarenal complications. PATIENT GROUP CKD is most common in senior and geriatric cats, but should be considered in any feline patient with ureterolithiasis, hyperthyroidism, retrovirus infection, systemic hypertension, cardiovascular disease or urinary tract infection. EVIDENCE BASE Most of our knowledge of the pathogenesis of CKD is extrapolated from human nephrology and experimental animal studies. There is, therefore, a need for further studies in cats. The prevalence of clinical signs in feline CKD is well documented. Several concurrent diseases associated with CKD have also been reported in cats, especially in the geriatric population, but there is no or only limited published evidence demonstrating a cause-and-effect relationship between most of these conditions and CKD. Studies performed over the past 15 years have nevertheless allowed identification of major risk factors (proteinuria, plasma phosphate and plasma creatinine) influencing the progression of feline CKD. CLINICAL CHALLENGES Clinical signs occur in the late stages of renal disease, so populations at higher risk of CKD should be screened routinely. CKD-associated complications (systemic hypertension, secondary renal hyperparathyroidism, hypokalaemia, anaemia, metabolic acidosis) must not be overlooked as they may affect the progression of disease. Disease progression is itself unpredictable and renal function may remain stable for extended periods. Most cats with early CKD do not progress to end-stage CKD before they die. AUDIENCE General practitioners play a major role in screening feline patients at risk of development or progression of CKD.
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Affiliation(s)
- Brice S Reynolds
- Clinical Research Unit, National Veterinary School of Toulouse, 23 chemin des Capelles, 31076 Toulouse cedex 03, France
| | - Hervé P Lefebvre
- Clinical Research Unit, National Veterinary School of Toulouse, 23 chemin des Capelles, 31076 Toulouse cedex 03, France
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Chakrabarti S, Syme HM, Brown CA, Elliott J. Histomorphometry of feline chronic kidney disease and correlation with markers of renal dysfunction. Vet Pathol 2012; 50:147-55. [PMID: 22773469 DOI: 10.1177/0300985812453176] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Chronic kidney disease is common in geriatric cats, but most cases have nonspecific renal lesions, and few studies have correlated these lesions with clinicopathological markers of renal dysfunction. The aim of this study was to identify the lesions best correlated with renal function and likely mediators of disease progression in cats with chronic kidney disease. Cats were recruited through 2 first-opinion practices between 1992 and 2010. When postmortem examinations were authorized, renal tissues were preserved in formalin. Sections were evaluated by a pathologist masked to all clinicopathological data. They were scored semiquantitatively for the severity of glomerulosclerosis, interstitial inflammation, and fibrosis. Glomerular volume was measured using image analysis; the percentage of glomeruli that were obsolescent was recorded. Sections were assessed for hyperplastic arteriolosclerosis and tubular mineralization. Kidneys from 80 cats with plasma biochemical data from the last 2 months of life were included in the study. Multivariable linear regression (P < .05) was used to assess the association of lesions with clinicopathological data obtained close to death. Interstitial fibrosis was the lesion best correlated with the severity of azotemia, hyperphosphatemia, and anemia. Proteinuria was associated with interstitial fibrosis and glomerular hypertrophy, whereas higher time-averaged systolic blood pressure was associated with glomerulosclerosis and hyperplastic arteriolosclerosis.
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Affiliation(s)
- S Chakrabarti
- Department of Veterinary Basic Sciences, Royal Veterinary College, Camden, London, UK.
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12
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Comparative study of chronic kidney disease in dogs and cats: Induction of myofibroblasts. Res Vet Sci 2010; 88:294-9. [DOI: 10.1016/j.rvsc.2009.09.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 09/09/2009] [Accepted: 09/14/2009] [Indexed: 01/02/2023]
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Kato T, Kurosawa TM, Taketo MM. Proteinuria-induced chronic kidney disease in the ICGN/Oa mice with a mutation of Tensin2 gene. Ren Fail 2009; 31:229-38. [PMID: 19288329 DOI: 10.1080/08860220802669834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
ICGN/Oa mice are used to study the pathophysiological mechanisms underlying proteinuria-induced chronic kidney disease (CKD). Recently, a mutation of tensin2 gene (Tns2) was suggested to be responsible for proteinuria in the inbred ICGN mice. We identified the wild-type (+/+), heterozygous (+/nep), and homozygous (nep/nep) ICGN/Oa mice by PCR assay. The homozygotes developed proteinuria, resulting in nephrotic syndrome (NS) as early as 5 weeks and CKD by 15 weeks. However, the heterozygotes did not show the symptoms of these renal failures. These results indicate that the homozygous tensin2 mutation is necessary for the ICGN/Oa mice to develop proteinuria-induced CKD. Furthermore, we examined the time course of tubulointerstitial fibrosis and the kinetics of tubular epithelial cells (TECs) in the ICGN/Oa mice using immunohistochemical and TUNEL assays. In the renal parenchyma of the five-week-old homozygotes, the expression of alpha-SMA and type I collagen were higher than those in the age-matched wild-type. Additionally, increased TEC proliferation was found at 5 weeks, and increased TEC apoptosis was by 15 weeks in the homozygotes. Tubulointerstitial fibrosis precedes TEC apoptosis in the proteinuria-induced CKD model mice, and that tubulointerstitial fibrosis may be the triggering event of the disease.
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Affiliation(s)
- Takashi Kato
- The Institute of Experimental Animal Sciences, Osaka University Medical School, Suita, Japan
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14
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Lawler DF, Evans RH, Chase K, Ellersieck M, Li Q, Larson BT, Satyaraj E, Heininger K. The aging feline kidney: a model mortality antagonist? J Feline Med Surg 2006; 8:363-71. [PMID: 17092751 PMCID: PMC10832924 DOI: 10.1016/j.jfms.2006.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2006] [Indexed: 11/20/2022]
Abstract
Traditional thinking views apparently non-programmed disruptions of aging, which medical science calls geriatric diseases, as separate from 'less harmful' morphological and physiological aging phenotypes that are more universally expected with passage of time (loss of skin elasticity, graying of hair coat, weight gain, increased sleep time, behavioral changes, etc). Late-life disease phenotypes, especially those involving chronic processes, frequently are complex and very energy-expensive. A non-programmed process of homeostatic disruption leading into a death trajectory seems inconsistent with energy intensive processes. That is, evolutionary mechanisms do not favor complex and prolonged energy investment in death. Taking a different view, the naturally occurring feline (Felis silvestris catus) renal model suggests that at least some diseases of late life represent only the point of failure in essentially survival-driven adaptive processes. In the feline renal model, individuals that succumbed to failure most frequently displayed progressive tubular deletion and peritubular interstitial fibrosis, but had longer mean life span than cats that died from other causes. Additionally, among cats that died from non-renal causes, those that had degrees of renal tubular deletion and peritubular interstitial fibrosis also had longer mean life span than those cats with no changes, even though causes of death differed minimally between these latter two groups. The data indicate that selective tubular deletion very frequently begins early in adult life, without a clear initiating phase or event. The observations support a hypothesis that this prolonged process may be intrinsic and protective prior to an ultimate point of failure. Moreover, given the genetic complexity and the interplay with associated risk factors, existing data also do not support the ideas that these changes are simple compensatory responses and that breed- or strain-based 'default' diseases are inevitable results of increasing individual longevity. Emerging molecular technology offers the future potential to further evaluate and refine these observations. At present, the existence of plastic and adaptive aging programming is suggested by these findings.
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Affiliation(s)
- Dennis F Lawler
- Nestle Research Center St. Louis, Nestle Purina PetCare Company, 2 Research South, St. Louis, MO 63164, USA.
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Arata S, Ohmi A, Mizukoshi F, Baba K, Ohno K, Setoguchi A, Tsujimoto H. Urinary Transforming Growth Factor-.BETA.1 in Feline Chronic Renal Failure. J Vet Med Sci 2005; 67:1253-5. [PMID: 16397385 DOI: 10.1292/jvms.67.1253] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Transforming growth factor-beta1 (TGF-beta1), an inflammatory cytokine, plays a role in tissue fibrosis, such as glomerular sclerosis and tubulointerstitial fibrosis of the kidneys. In the present study, the urinary TGF-beta1 level of cats diagnosed with chronic renal failure (CRF) was measured to investigate its relationship to the pathogenesis of feline CRF. Urinary TGF-beta1 levels (TGF-beta1/creatinine ratio) were significantly increased compared with healthy controls, whereas serum levels of TGF-beta1 were not. These results indicate that TGF-beta1 is expressed in the kidneys of CRF cats, and that it was reflected in the urinary TGF-beta1 level. Therefore, TGF-beta1 may play a role in feline CRF, and urinary TGF-beta1 could be used as a clinical marker for renal fibrosis.
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Affiliation(s)
- Sayaka Arata
- Depertment of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
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16
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Yabuki A, Matsumoto M, Taniguchi K, Suzuki S. The effects of microwave-irradiated fixation for postmortem changes of the kidney. J Vet Med Sci 2004; 66:705-7. [PMID: 15240947 DOI: 10.1292/jvms.66.705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the present study, we evaluated the advantages of microwave-irradiated fixation for postmortem autolysis of the kidney. Mouse kidneys, sampled at 0, 1, 3, 5, 10, 15, 20 and 25 hr after death, were fixed with 10% neutral formalin by microwave irradiation (MWI; 20 sec/500 W) and by conventional immersion. They were then examined with light and electron microscopy, morphometrics and immunohistochemicals. Light microscopic and morphometric observations showed that structural preservation effect of MWI was limited to the proximal convoluted tubules at 25 hr. Contrary, mild ultrastructural damage by MWI was found in the glomeruli at 0 and 15 hr. Immunohistochemistry for renin and alpha-smooth muscle actin showed no apparent differences between MWI and the immersion.
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Affiliation(s)
- Akira Yabuki
- Department of Veterinary Anatomy, Faculty of Agriculture, Kagoshima University, Japan
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17
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Mizuno S, Mizuno-Horikawa Y, Kurosawa T. Immunohistochemical analysis of molecular events in tubulo-interstitial fibrosis in a mouse model of diffuse mesangial sclerosis (ICGN strain). J Vet Med Sci 2001; 63:299-307. [PMID: 11307931 DOI: 10.1292/jvms.63.299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Diffuse mesangial sclerosis (DMS) is one of the hereditary glomerular diseases and histologically characterized by severe glomerulosclerosis and subsequent tubulo-interstitial fibrosis (TIF). In DMS patients, renal dysfunction correlates well with TIF, rather than with glomerular lesions. Thus, molecular mechanisms whereby TIF in DMS progresses should be addressed. Previously, we found that nephrotic ICGN mice manifest DMS-like lesions and develop renal dysfunction in accordance with onset of TIF. In the present study, we investigated fibrogenic events involved in the progression of TIF after DMS manifestation, using the DMS mouse model. Immunohistochemistry revealed that expression of transforming growth factor-beta (TGF-beta) was rare in the interstitial cells of the nephrotic mice at the early-stage of DMS, while the TGF-beta expression became evident in the late-stage DMS mice. Platelet-derived growth factor (PDGF) was mildly expressed in the distal tubules of the early-stage DMS mice, whereas the PDGF expression markedly increased at the late-stage of DMS. As a result, alpha-actin-positive myofibroblastic cells were found dominant in the interstitial spaces of the late-stage DMS mice. Finally, TIF became severe in accordance with the overexpressions of these molecules. Our results suggest that in our murine model: 1) persistent proteinuria leads to over-expression of TGF-beta and PDGF in non-glomerular areas; 2) these cytokines provoke interstitial myofibroblast accumulation; and 3) the myofibroblasts produce fibrotic matrix proteins in the interstitial spaces. This process may possibly contribute to the development of TIF in DMS patients.
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Affiliation(s)
- S Mizuno
- The Institute of Experimental Animal Sciences, Osaka University Medical School, Suita, Japan
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