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Baskerville CL, Chockalingham S, Harris PA, Bailey SR. The effect of insulin on equine lamellar basal epithelial cells mediated by the insulin-like growth factor-1 receptor. PeerJ 2018; 6:e5945. [PMID: 30519508 PMCID: PMC6275117 DOI: 10.7717/peerj.5945] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 10/16/2018] [Indexed: 12/26/2022] Open
Abstract
Background In horses and ponies, insulin dysregulation leading to hyperinsulinemia may be associated with increased risk of laminitis, and prolonged infusion of insulin can induce the condition. It is unclear whether insulin may have a direct or indirect effect on the lamellar tissues. Insulin is structurally related to insulin-like growth factor (IGF-1), and can bind the IGF-1 receptor, albeit at a lower affinity than IGF-1. Methods Immunohistochemistry was performed on formalin-fixed lamellar tissue sections from six normal horses, euthanised for non-research purposes, using an anti-IGF-1 receptor antibody. In further studies, lamellar epithelial cells were obtained by collagenase digestion from the hooves of 18 normal horses, also euthanised for non-research purposes, and incubated for 48 h in the presence of insulin (0–2,000 m IU/ml). The increase in cell numbers was determined using a cell proliferation assay, and compared to the effect of zero insulin using one-way ANOVA. Results Immunohistochemistry demonstrated IGF-1 receptors on lamellar epidermal epithelial cells. With cultured cells, insulin caused a concentration-dependent increase in cell proliferation compared to untreated cells (maximal effect 63.3 ± 12.8% more cells after 48 h with 1,000 m IU/ml insulin; P < 0.01). Co-incubation with a blocking antibody against the IGF-1 receptor significantly inhibited the proliferative effect of insulin (P < 0.01). Discussion These results demonstrate that IGF-1 receptors are present on lamellar epithelial cells. At high physiological concentrations, insulin may activate these cells, by a mechanism involving IGF-1 receptors, resulting in a proliferative effect. This mechanism could help to explain the link between hyperinsulinemia and laminitis.
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Affiliation(s)
- Courtnay L Baskerville
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Subu Chockalingham
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Patricia A Harris
- Equine Studies Group, WALTHAM Centre for Pet Nutrition, Melton Mowbray, Leicestershire, UK
| | - Simon R Bailey
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia
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Patan-Zugaj B, Gauff FC, Egerbacher M, Licka TF. Endotoxin-induced changes of type VII collagen- cleaving matrix metalloproteinases in lamellar tissue of extracorporeally perfused equine limbs. Am J Vet Res 2018; 79:986-994. [PMID: 30153058 DOI: 10.2460/ajvr.79.9.986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the effect of lipopolysaccharide (LPS) on type VII collagen- cleaving matrix metalloproteinases (MMPs) in the lamellar tissue of extracorporeally perfused equine limbs. SAMPLE 10 right forelimbs and 3 left forelimbs collected from 10 adult horses after slaughter at a licensed abattoir. PROCEDURES Extracorporeal perfusion of the isolated equine limbs was performed for 10 hours under physiologic conditions (control-perfused limbs; n = 5) and with the addition of 80 ng of LPS/L of perfusate (LPS-perfused limbs; 5). Lamellar tissue specimens were then collected from the dorsal aspect of the hooves. Additionally, corresponding control specimens were collected from the 3 nonperfused left forelimbs. Immunohistochemical analysis was performed on paraffin-embedded tissue blocks with antibodies against total (latent and active) MMP-1, MMP-2, MMP-8, and MMP-9 as well as antibody against active MMP-9. Intensity of immunohistochemical staining was scored, and stain distribution in the lamellar tissue was noted. RESULTS Staining intensity of total and active MMP-9 was significantly increased in LPS-perfused versus control-perfused limbs. No such difference was identified for MMP-1, MMP-2, and MMP-8. CONCLUSIONS AND CLINICAL RELEVANCE Of the 4 MMPs that are capable of degrading type VII collagen, MMP-9 was the only one for which production increased in the lamellar tissue of isolated equine limbs perfused with versus without a clinically relevant concentration of LPS. These results suggested that MMP-9 may be involved in initiation of pathological changes in lamellar tissue in endotoxin-induced laminitis, whereas MMP-1, MMP-2, and MMP-8 may be less relevant.
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Cell In Situ Zymography: Imaging Enzyme-Substrate Interactions. Methods Mol Biol 2017. [PMID: 28608206 DOI: 10.1007/978-1-4939-7111-4_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Zymography has long been used for the detection of substrate-specific enzyme activity. In situ zymography (ISZ), an adaptation from the conventional substrate zymography, is a widely employed technique useful for the detection, localization, and estimation of enzyme-substrate interactions in tissues. Here, we describe a protocol to detect 'in position' matrix metalloproteinase (MMP) activity in cells utilizing H9c2 cardiomyoblasts as a model. This technique is primarily adopted from the method used for histological sections and is termed as 'Cell in situ Zymography'. It is a simple, sensitive, and quantifiable methodology to assess the functional activity of an enzyme 'on site/in position' in cell culture.
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Kanomata N, Hasebe T, Moriya T, Ochiai A. Simultaneous demonstration of gelatinolytic activity, morphology, and immunohistochemical reaction using zymography film. Med Mol Morphol 2013; 46:193-7. [PMID: 23397548 DOI: 10.1007/s00795-013-0021-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/09/2012] [Indexed: 10/27/2022]
Abstract
In situ zymography has been used to assess gelatinolytic activity, which is mainly due to matrix metalloproteinases (MMPs) in cancer tissues. MMPs play an important role in cancer invasion and metastasis. Film in situ zymography (FIZ) enables the in situ evaluation of gelatinolytic activity with high reproducibility. In this article, we report a study of FIZ, in a case of breast cancer with an invasive carcinoma component showing clear gelatinolytic activity, and in a non-invasive carcinoma component showing little gelatinolytic activity. Immunohistochemistry on FIZ was also performed. The simultaneous detection of gelatinolytic activity and immunohistochemical reaction was established in a single film. Immunohistochemistry on FIZ may have good potential for the investigation of cancer microenvironment.
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Affiliation(s)
- Naoki Kanomata
- Department of Pathology, Kawasaki Medical School, Matsushima 577, Kurashiki, Okayama, 701-0192, Japan,
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Chhabra A, Jaiswal A, Malhotra U, Kohli S, Rani V. Cell in situ zymography: an in vitro cytotechnology for localization of enzyme activity in cell culture. In Vitro Cell Dev Biol Anim 2012; 48:463-8. [PMID: 22821629 DOI: 10.1007/s11626-012-9529-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/14/2012] [Indexed: 12/20/2022]
Abstract
In situ zymography is a unique technique for detection and localization of enzyme-substrate interactions majorly in histological sections. Substrate with quenched fluorogenic molecule is incorporated in gel over which tissue sections are mounted and then incubated in buffer. The enzymatic activity is observed in the form of fluorescent signal. With the advancements in the field of biological research, use of in vitro cell culture has become very popular and holds great significance in multiple fields including inflammation, cancer, stem cell biology and the still emerging 3-D cell cultures. The information on analysis of enzymatic activity in cell lines is inadequate presently. We propose a single-step methodology that is simple, sensitive, cost-effective, and functional to perform and study the 'in position' activity of enzyme on substrate for in vitro cell cultures. Quantification of enzymatic activity to carry out comparative studies on cells has also been illustrated. This technique can be applied to a variety of enzyme classes including proteases, amylases, xylanases, and cellulases in cell cultures.
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Affiliation(s)
- Aastha Chhabra
- Department of Biotechnology, Jaypee Institute of Information Technology, A-10, Sector-62, Noida, 201307, Uttar Pradesh, India
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Gkantidis N, Katsaros C, Chiquet M. Detection of gelatinolytic activity in developing basement membranes of the mouse embryo head by combining sensitive in situ zymography with immunolabeling. Histochem Cell Biol 2012; 138:557-71. [PMID: 22688677 DOI: 10.1007/s00418-012-0982-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2012] [Indexed: 12/16/2022]
Abstract
Genetic evidence indicates that the major gelatinases MMP-2 and MMP-9 are involved in mammalian craniofacial development. Since these matrix metalloproteinases are secreted as proenzymes that require activation, their tissue distribution does not necessarily reflect the sites of enzymatic activity. Information regarding the spatial and temporal expression of gelatinolytic activity in the head of the mammalian embryo is sparse. Sensitive in situ zymography with dye-quenched gelatin (DQ-gelatin) has been introduced recently; gelatinolytic activity results in a local increase in fluorescence. Using frontal sections of wild-type mouse embryo heads from embryonic day 14.5-15.5, we optimized and validated a simple double-labeling in situ technique for combining DQ-gelatin zymography with immunofluorescence staining. MMP inhibitors were tested to confirm the specificity of the reaction in situ, and results were compared to standard SDS-gel zymography of tissue extracts. Double-labeling was used to show the spatial relationship in situ between gelatinolytic activity and immunostaining for gelatinases MMP-2 and MMP-9, collagenase 3 (MMP-13) and MT1-MMP (MMP-14), a major activator of pro-gelatinases. Strong gelatinolytic activity, which partially overlapped with MMP proteins, was confirmed for Meckel's cartilage and developing mandibular bone. In addition, we combined in situ zymography with immunostaining for extracellular matrix proteins that are potential gelatinase substrates. Interestingly, gelatinolytic activity colocalized precisely with laminin-positive basement membranes at specific sites around growing epithelia in the developing mouse head, such as the ducts of salivary glands or the epithelial fold between tongue and lower jaw region. Thus, this sensitive method allows to associate, with high spatial resolution, gelatinolytic activity with epithelial morphogenesis in the embryo.
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Affiliation(s)
- Nikolaos Gkantidis
- Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Freiburgstrasse 7, 3010 Bern, Switzerland
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Medina-Torres CE, Mason SL, Floyd RV, Harris PA, Mobasheri A. Hypoxia and a hypoxia mimetic up-regulate matrix metalloproteinase 2 and 9 in equine laminar keratinocytes. Vet J 2011; 190:e54-e59. [PMID: 21459025 DOI: 10.1016/j.tvjl.2011.02.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 02/24/2011] [Accepted: 02/28/2011] [Indexed: 12/15/2022]
Abstract
The aim of this study was to determine if hypoxia and the hypoxia mimetic cobalt chloride regulate the activity of matrix metalloproteinase (MMP)-2 and -9 in cultures of equine hoof keratinocytes. These effects were assessed in primary cultures of laminar keratinocytes using gelatin zymography. Incubation of keratinocytes with cobalt chloride significantly increased the levels of active MMP-2 compared to untreated controls. Hypoxia significantly increased the expression of active MMP-2 and -9 in keratinocyte cultures. This up-regulation was observed after 6h and peaked at 24h. The study findings provide novel evidence of a potential link between hypoxia within the hoof and up-regulation of MMPs which may in turn result in damage to the lamellar basement membrane.
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Affiliation(s)
- Carlos E Medina-Torres
- School of Veterinary Science, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZJ, UK
| | - Sarah L Mason
- School of Veterinary Science, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZJ, UK
| | - Rachel V Floyd
- School of Biomedical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Pat A Harris
- Equine Studies Group, WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Melton Mowbray, Leicestershire LE14 4RT, UK
| | - Ali Mobasheri
- School of Veterinary Science and Medicine, Faculty of Medicine and Health Sciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK.
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Aldonyte R, Tunaitis V, Surovas A, Suriakaite K, Jarmalaviciute A, Magnusson KE, Pivoriunas A. Effects of major human antiprotease alpha-1-antitrypsin on the motility and proliferation of stromal cells from human exfoliated deciduous teeth. Regen Med 2010; 5:633-43. [PMID: 20632864 DOI: 10.2217/rme.10.18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
AIM Intrinsic tissue regeneration mechanisms are still not fully understood. The destruction/reconstruction processes are usually in fine balance; however, this can be easily destroyed, for example in the environment of chronic inflammation. One of the major proteins present at the inflammatory sites is the multifunctional protein alpha-1-antitrypsin (AAT). In this study, potential therapeutic effects of this major human antiprotease on progenitor cells are assessed. MATERIALS & METHODS Stromal cells from human exfoliated deciduous teeth (SHEDs) were used, which are similar to the mesenchymal stromal cells isolated from other tissues. SHEDs were cultivated in the presence of subphysiological, physiological and inflammatory concentrations of AAT, and their proliferation and motility traits were assayed. Some intracellular signaling pathways, AAT internalization by SHEDs and their matrix metalloprotease profile were studied in parallel. RESULTS Physiologic and inflammatory concentrations of AAT significantly increased the cell proliferation rate, induced phosphorylation of several key protein kinases and increased the amount of secreted active gelatinases. Moreover, cells exposed to physiologic and inflammatory levels of AAT were able to invade and migrate more efficiently. Subphysiologic AAT levels did not change cell behavior significantly. CONCLUSION AAT at physiologic and inflammatory concentrations positively modulates the proliferation and motility of SHEDs in vitro. These results suggest the importance of AAT in the maintenance and regulation of tissue progenitor cells in vivo.
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Affiliation(s)
- Ruta Aldonyte
- State Institute of Science "Centre of Innovative Medicine", Vilnius University, Zygimantu 9, Vilnius LT-01102, Lithuania.
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Loftus JP, Williams JM, Belknap JK, Black SJ. In vivo priming and ex vivo activation of equine neutrophils in black walnut extract-induced equine laminitis is not attenuated by systemic lidocaine administration. Vet Immunol Immunopathol 2010; 138:60-9. [DOI: 10.1016/j.vetimm.2010.06.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 06/16/2010] [Accepted: 06/21/2010] [Indexed: 12/24/2022]
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van Eps AW. Therapeutic hypothermia (cryotherapy) to prevent and treat acute laminitis. Vet Clin North Am Equine Pract 2010; 26:125-33. [PMID: 20381741 DOI: 10.1016/j.cveq.2010.01.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Digital hypothermia successfully reduces the severity of experimentally induced laminitis. Continuous-distal limb cryotherapy may be a useful technique in clinical cases that are at risk of developing laminitis. This article examines the effects of hypothermia on tissue as well as the rationale, and suggested protocols for the usage of distal limb cryotherapy in the prevention and treatment of laminitis.
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Affiliation(s)
- Andrew W van Eps
- School of Veterinary Science, University of Queensland, Slip Road, St Lucia, QLD 4072, Australia.
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12
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13
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French KR, Pollitt CC. Equine laminitis: loss of hemidesmosomes in hoof secondary epidermal lamellae correlates to dose in an oligofructose induction model: an ultrastructural study. Equine Vet J 2010; 36:230-5. [PMID: 15147130 DOI: 10.2746/0425164044877125] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY Light microscopical studies show that the key lesion of laminitis is separation at the hoof lamellar dermal-epidermal interface. More precise knowledge of the damage occurring in the lamellar basement membrane zone may result if laminitis affected tissue is examined with the transmission electron microscope. This could lead to better understanding of the pathogenesis of lesions and the means of treatment or prevention. OBJECTIVES To investigate the ultrastructure of acute laminitis as disease of greater severity is induced by increasing oligofructose (OF) dosage. METHODS Three pairs of normal horses, dosed with OF at 7.5, 10 and 12.5 g/kg bwt via nasogastric intubation, developed laminitis 48 h later. Following euthanasia, their forefeet were processed for transmission electron microscopy. Lamellar basal cell hemidesmosome (HD) numbers and the distance between the basal cell plasmalemma and the lamina densa of the basement membrane were estimated and compared to control tissue. RESULTS Increasing OF dosage caused greater HD loss and more severe laminitis. The characteristic separation of the basement membrane, cytoskeleton failure and rounded basal cell nuclei results from combined HD dysassembly and anchoring filament failure. CONCLUSIONS Without properly assembled HDs, dysadhesion between the lamina densa of the basement membrane (BM) and epidermal basal cells occurs, emphasising the fundamental importance of HDs in maintaining attachment at the lamellar interface. Medical conditions that trigger lamellar matrix metalloproteinase (MMP) activation and/or compromise entry of glucose into lamellar basal cells appear to promote loss and failure of HDs and, therefore, laminitis development. POTENTIAL RELEVANCE A correlation between lameness severity and escalating loss of lamellar HDs now exists. Therapy aimed at protecting the lamellar environment from haematogenous delivery of MMP activators or from glucose deprivation may control laminitis development.
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Affiliation(s)
- K R French
- Australian Equine Laminitis Research Unit, School of Veterinary Science, Faculty of Natural Resources Agriculture and Veterinary Science, The University of Queensland, Brisbane, Queensland 4072, Australia
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Mobasheri A, Critchlow K, Clegg PD, Carter SD, Canessa CM. Chronic equine laminitis is characterised by loss of GLUT1, GLUT4 and ENaC positive laminar keratinocytes. Equine Vet J 2010; 36:248-54. [PMID: 15147133 DOI: 10.2746/0425164044877224] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY Equine laminitis is a multifactorial connective tissue disorder with major implications for the welfare of horses. There are few published studies on phenotypic markers for identification of equine laminar keratinocytes using immunohistochemical techniques. OBJECTIVES To establish whether the epithelial sodium channel (ENaC) and the GLUT1 and GLUT4 facilitative glucose transporters may be used as phenotypic markers for identification of equine laminar keratinocytes using immunohistochemical techniques to monitor changes in the keratinocyte population in laminitis. METHODS Histology and immunohistochemistry using polyclonal antibodies to the alpha subunit of ENaC (alphaENaC), GLUT1 and GLUT4 were used to compare the distribution of these proteins in normal and laminitic equine laminae. RESULTS Immunohistochemistry with antibodies to alphaENaC, GLUT1 and GLUT4 confirmed the abundant expression of all 3 membrane proteins in healthy laminar keratinocytes. However, in laminitis, the Haematoxylin Van Gieson (HVG) technique revealed disordered laminar arrays and replacement with fibrous scar tissue. Immunostaining of laminitic samples confirmed the loss of alphaENaC, GLUT1 and GLUT4 positive keratinocytes. Other connective tissue cells did not stain positive for these proteins. CONCLUSIONS This is the first report of alphaENaC and GLUT1/GLUT4 protein expression in equine laminar keratinocytes, which also confirms that the loss of laminar structure and function in chronic laminitis is accompanied by the loss of laminar keratinocytes. POTENTIAL RELEVANCE alphaENaC, GLUT1 and GLUT4 may be used as phenotypic markers of metabolically active, differentiated equine laminar keratinocytes. Further in vitro studies are necessary to determine the effects of hypoxia, bacterial endotoxins, vasoactive amines, lactic acid and prostaglandins on the expression and activity of these plasma membrane keratinocyte markers.
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Affiliation(s)
- A Mobasheri
- Connective Tissue and Molecular Pathogenesis Research Groups, Faculty of Veterinary Science, University of Liverpool, Liverpool L69 7ZJ, UK
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Merritt A. Where does the subject of black walnut extract-induced laminitis fit into a colic symposium? Equine Vet J 2010; 37:289-91. [PMID: 16028614 DOI: 10.2746/0425164054529355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Riggs LM, Krunkosky TM, Noschka E, Boozer LA, Moore JN, Robertson TP. Comparison of characteristics and enzymatic products of leukocytes in the skin and laminar tissues of horses administered black walnut heartwood extract or lipopolysaccharide. Am J Vet Res 2009; 70:1383-90. [DOI: 10.2460/ajvr.70.11.1383] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Noschka E, Vandenplas ML, Hurley DJ, Moore JN. Temporal aspects of laminar gene expression during the developmental stages of equine laminitis. Vet Immunol Immunopathol 2009; 129:242-53. [DOI: 10.1016/j.vetimm.2008.11.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Clutterbuck AL, Harris P, Allaway D, Mobasheri A. Matrix metalloproteinases in inflammatory pathologies of the horse. Vet J 2008; 183:27-38. [PMID: 19022687 DOI: 10.1016/j.tvjl.2008.09.022] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 09/05/2008] [Accepted: 09/30/2008] [Indexed: 01/09/2023]
Abstract
The extracellular matrix (ECM) of connective tissue is constantly being remodelled to allow for growth and regeneration. Normal tissue maintenance requires the ECM components to be degraded and re-synthesised in relatively equal proportions. This degradation is facilitated by matrix metalloproteinases (MMPs) and their proteolytic action is controlled primarily by the tissue inhibitors of metalloproteinases (TIMPs). Both MMPs and TIMPs exist in a state of dynamic equilibrium, with a slight excess of one or the other depending on the need for either ECM breakdown or synthesis. Long-term disruption to this balance between MMPs and TIMPs will have pathological consequences. Matrix metalloproteinases are involved in a number of diseases in mammals, including the horse. Excess MMP activity can cause ECM destruction, as seen in the lamellar basement membrane in laminitis and the articular cartilage in osteoarthritis. Matrix metalloproteinase under-activity can potentially impede healing by preventing fibrinolysis in fibrotic conditions and the removal of scar tissue in wounds. Matrix metalloproteinases also degrade non-ECM proteins and regulate cell behaviour via the release of growth factors from the substrates they cleave, increasing the scope of their effects. This review looks at the involvement of MMPs in equine health and pathologies, whilst exploring the potential consequences of therapeutic intervention.
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Affiliation(s)
- Abigail L Clutterbuck
- Division of Veterinary Medicine, School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, College Road, Sutton Bonington, Leicestershire, LE12 5RD, United Kingdom
| | - Pat Harris
- WALTHAM Centre for Pet Nutrition, Freeby Lane, Waltham on the Wolds, Melton Mowbray, Leicestershire, LE14 4RT, United Kingdom
| | - David Allaway
- WALTHAM Centre for Pet Nutrition, Freeby Lane, Waltham on the Wolds, Melton Mowbray, Leicestershire, LE14 4RT, United Kingdom
| | - Ali Mobasheri
- Division of Veterinary Medicine, School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, College Road, Sutton Bonington, Leicestershire, LE12 5RD, United Kingdom.
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Loftus JP, Johnson PJ, Belknap JK, Pettigrew A, Black SJ. Leukocyte-derived and endogenous matrix metalloproteinases in the lamellae of horses with naturally acquired and experimentally induced laminitis. Vet Immunol Immunopathol 2008; 129:221-30. [PMID: 19101039 DOI: 10.1016/j.vetimm.2008.11.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
RATIONALE Inflammation and dysregulation of endogenous matrix metalloproteinase (MMP) production are implicated in the development of equine laminitis. In this study, we examine quantitative relationships among levels of leukocyte-derived proMMP-9 and MMP-9, lamellar proMMP-2 and MMP-2, and expression of proMMP-2 processing enzymes, MT1-MMP/PACE4, as steps towards determining whether inflammation and dysregulation of endogenous MMP production are independent or co-dependent processes. ANIMALS Archived samples of lamellae from horses with naturally acquired laminitis (n = 12), and from horses administered a pro-laminitic gastric bolus of starch gruel were used, the latter horses falling into two groups: (i) responders (CHO-R, n = 7), which developed Obel grade 3-lameness and (ii) non-responders (CHO-NR, n = 4), which did not become lame. METHODS Lamellar tissue extracts were analyzed by gelatin zymography to determine gelatinase content and by a myeloperoxidase ELISA to quantify relative monocyte/neutrophil content in the tissue. Real-time PCR was employed to measure gene expression of MT1-MMP and PACE4. RESULTS AND CONCLUSIONS Extracts of lamellae from control horses, CHO-NR and horses with chronic (non-aggravated) laminitis had similarly low levels of pro and processed MMP-9 and MMP-2. In contrast, proMMP-9 was significantly elevated in extracts of lamellae from CHO-R and horses with naturally acquired acute and aggravated chronic laminitis. Lamellar MMP-2 was also increased significantly in the CHO-R and aggravated chronic laminitis groups, although not in the horses with naturally acquired acute laminitis. Concentrations of proMMP-9 correlated directly with myeloperoxidase content in lamellar extracts, suggesting production/induction by inflammatory leukocytes. In contrast, concentrations of proMMP-2 and MMP-2 were unrelated to concentrations of myeloperoxidase or proMMP-9 suggesting that leukocyte infiltration and dysregulation of endogenous MMP-2 are independent processes most likely with distinct inducers. Neither MT1-MMP nor PACE4 gene expression was elevated relative to controls in any group; this is discussed with respect to proMMP-2 processing in disease. In addition, variability in relative concentrations of lamellar MMPs observed among horses with Obel grade 3-lameness is discussed in the context of laminitis risk assessment and disease outcome.
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Affiliation(s)
- John P Loftus
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
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Loftus JP, Belknap JK, Black SJ. Matrix metalloproteinase-9 in laminae of black walnut extract treated horses correlates with neutrophil abundance. Vet Immunol Immunopathol 2006; 113:267-76. [PMID: 16822550 DOI: 10.1016/j.vetimm.2006.05.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 05/16/2006] [Accepted: 05/17/2006] [Indexed: 11/16/2022]
Abstract
We sought to determine whether a correlation exists between neutrophil infiltration and tissue matrix metalloproteinase-9 (MMP-9) content in digital laminae collected during the prodromal and acute phases of laminitis in horses treated with an aqueous black walnut heartwood extract (BWE). Hoof laminar tissue was obtained at the onset of leukopenia and at the onset of clinical signs of lameness from BWE-treated horses and at equivalent times from control horses. Thin sections of laminae were screened for neutrophils by immunohistochemistry with an anti-CD13 monoclonal antibody and extracts of the same tissues were screened for SDS-renaturable and native MMP-9 activities by denaturing and non-denaturing gelatin zymography. Samples were also screened for MMP-2 and MMP-9 gene expression by RT-qPCR. Control laminae were devoid of both MMP-9 and neutrophils, whereas neutrophils and SDS-renaturable MMP-9 activity were detected in laminae from BWE-treated horses and were strongly correlated at the acute stage of the disease at which time laminar MMP-9 gene expression was significantly (15-fold) elevated. In contrast, BWE-treatment did not significantly elevate MMP-2 gene or protein expression in the laminae. Interestingly, MMP-9 that was present in extracts of laminae from BWE-treated horses at both the prodromal and acute stages of the disease was mainly in the zymogen form, suggesting that the accumulation of the MMP did not contribute to pathology during these stages. However, elevated presence of the MMP-9 zymogen in the tissue would predispose it to catastrophic damage should conditions arise that cleave the regulatory propeptide domain.
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Affiliation(s)
- John P Loftus
- Department of Veterinary and Animal Sciences, University of Massachusetts, Paige Laboratory, Amherst, MA 01003, USA
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22
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Shirahane K, Yamaguchi K, Koga K, Watanabe M, Kuroki S, Tanaka M. Hepatic ischemia/reperfusion injury is prevented by a novel matrix metalloproteinase inhibitor, ONO-4817. Surgery 2006; 139:653-64. [PMID: 16701099 DOI: 10.1016/j.surg.2005.10.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 10/06/2005] [Accepted: 10/11/2005] [Indexed: 12/14/2022]
Abstract
BACKGROUND Matrix metalloproteinases (MMPs) play an important role in inflammation and neoplastic invasion and metastasis. Little is known about the effects of MMP inhibitors on hepatic ischemia/reperfusion injury. The aim of this study is to examine the inhibitory effects of ONO-4817 (oral inhibitor of MMPs) in rats. METHODS Hepatic ischemia/reperfusion was induced in male Wister rats by clamping the portal vein and hepatic artery. The animals were randomized into an ONO-4817 group (300 mg/kg body weight per/day) and a vehicle group by oral gavage of a test substance. Serum alanine aminotransferase, histologic changes, gelatinolytic activity, MMP-2 and MMP-9 activities, tissue inhibitor of metalloproteinase 2 (TIMP-2) messenger RNA (mRNA) levels, and mRNA and serum levels of tumor necrosis factor alpha (TNFalpha) and interleukin 1beta (IL-1beta) were measured in both groups. RESULTS ONO-4817 prevented ischemia/reperfusion injury to the hepatocytes as shown by significant reductions of serum alanine aminotransferase and less severe histologic changes. Gelatinolytic activity was inhibited markedly in the liver of the ONO-4817 group as demonstrated by film in situ zymography. MMP-9 and MMP-2 activities also were inhibited in the ONO-4817 group as shown by gelatin zymography. TIMP-2 mRNA levels showed no significant differences between the 2 groups. TNFalpha mRNA showed no downregulation, but IL-1beta mRNA was downregulated in the liver of the ONO-4817 group 1 to 3 hours after reperfusion. Serum levels of TNFalpha and IL-1beta showed a significant decrease in the ONO-4817 group, compared with the vehicle group after reperfusion. CONCLUSIONS Hepatic ischemia/reperfusion injury was improved by a novel MMP inhibitor, ONO-4817, not only by inhibition of gelatinolytic activity but also by a decrease in release of inflammatory cytokines.
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Affiliation(s)
- Kengo Shirahane
- Department of Surgery and Oncology, Graduate School of Medical Sciences, Kyushu University, Japan
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23
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Kuwano A, Ueno T, Katayama Y, Nishiyama T, Arai K. Unilateral Basement Membrane Zone Alteration of the Regenerated Laminar Region in Equine Chronic Laminitis. J Vet Med Sci 2005; 67:685-91. [PMID: 16082116 DOI: 10.1292/jvms.67.685] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Between the laminar epidermis and the laminar dermis of laminar region (LR) in equine foot, it can be observed the basement membrane zone (BMZ), which is composed of a basement membrane and its accompaniments like the hemidesmosome and anchoring fibril. Alteration in the BMZ in equine laminitis is possibly related with not only development but also recovery outcome and recurrence of this disease. However, there is little known about the structure of the BMZ during the recovery phase of this disease. To assess the condition of the BMZ of LR affected by chronic laminitis, the tissue was examined in three cases at two weeks, four weeks and three months after the onset of laminitis, using pathological, immunohistochemical and electron microscopic techniques. Histologically in all laminitis cases, there was a regenerated laminar epidermis with proliferating keratinocytes between the Stratum medium and the dermis, but it included the undeveloped secondary epidermal laminae (ud-SELs) structure in one side of the primary epidermal laminae, especially in the part of the deep area of LR. Immunohistochemical results were positive for the anti-type IV collagen, anti-type VII collagen and anti-laminin 5 antibodies in the most BMZs. However, partial BMZs adjacent to the ud-SELs were negative for the anti-type VII collagen and anti-laminin 5 antibodies. Ultrastructurally, in the BMZ of the ud-SEL, the lamina densa and the lamina lucida were present. In contrast, the anchoring fibrils and the hemidesmosomes were either absent, or present at lower than normal levels. In conclusion, the present study indicated that the part of regenerated LR in chronic laminitis was not able to fully restore to construct the BMZ for a long time, especially in the unilateral side of laminar epidermis. It might be related with recurrence of this disease.
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Affiliation(s)
- Atsutoshi Kuwano
- Clinical Science & Pathobiology Division, Equine Research Institute, Japan Racing Association, Tochigi
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24
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French KR, Pollitt CC. Equine laminitis: glucose deprivation and MMP activation induce dermo-epidermal separation in vitro. Equine Vet J 2004; 36:261-6. [PMID: 15147135 DOI: 10.2746/0425164044877170] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
REASONS FOR PERFORMING STUDY Acute laminitis is characterised by hoof lamellar dermal-epidermal separation at the basement membrane (BM) zone. Hoof lamellar explants cultured in vitro can also be made to separate at the basement membrane zone and investigating how this occurs may give insight into the poorly understood pathophysiology of laminitis. OBJECTIVES To investigate why glucose deprivation and metalloproteinase (MMP) activation in cultured lamellar explants leads to dermo-epidermal separation. METHODS Explants, cultured without glucose or with the MMP activator p-amino-phenol-mercuric acetate (APMA), were subjected to tension and processed for transmission electron microscopy (TEM). RESULTS Without glucose, or with APMA, explants under tension separated at the dermo-epidermal junction. This in vitro separation occurred via 2 different ultrastructural processes. Lack of glucose reduced hemidesmosomes (HDs) numbers until they disappeared and the basal cell cytoskeleton collapsed. Anchoring filaments (AFs), connecting the basal cell plasmalemma to the BM, were unaffected although they failed under tension. APMA activation of constituent lamellar MMPs did not affect HDs but caused AFs to disappear, also leading to dermo-epidermal separation under tension. CONCLUSIONS Natural laminitis may occur in situations where glucose uptake by lamellar basal cells is compromised (e.g. equine Cushing's disease, obesity, hyperlipaemia, ischaemia and septicaemia) or when lamellar MMPs are activated (alimentary carbohydrate overload). POTENTIAL RELEVANCE Therapies designed to facilitate peripheral glucose uptake and inhibit lamellar MMP activation may prevent or ameliorate laminitis.
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Affiliation(s)
- K R French
- Australian Equine Laminitis Research Unit, School of Veterinary Science, Faculty of Natural Resources Agriculture and Veterinary Science, The University of Queensland, Brisbane 4072, Australia
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25
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Frederiks WM, Mook ORF. Metabolic mapping of proteinase activity with emphasis on in situ zymography of gelatinases: review and protocols. J Histochem Cytochem 2004; 52:711-22. [PMID: 15150280 DOI: 10.1369/jhc.4r6251.2004] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Proteases are essential for protein catabolism, regulation of a wide range of biological processes, and in the pathogenesis of many diseases. Several techniques are available to localize activity of proteases in tissue sections or cell preparations. For localization of the activity of matrix metalloproteinases, in situ zymography was introduced some decades ago. The procedure is based on zymography using SDS polyacrylamide gels containing gelatin, casein, or fibrin as substrate. For in situ zymography, either a photographic emulsion containing gelatin or a fluorescence-labeled proteinaceous macromolecular substrate is brought into contact with a tissue section or cell preparation. After incubation, enzymatic activity is revealed as white spots in a dark background or as black spots in a fluorescent background. However, this approach does not allow precise localization of proteinase activity because of limited sensitivity. A major improvement in sensitivity was achieved with the introduction of dye-quenched (DQ-)gelatin, which is gelatin that is heavily labeled with FITC molecules so that its fluorescence is quenched. After cleavage of DQ-gelatin by gelatinolytic activity, fluorescent peptides are produced that are visible against a weakly fluorescent background. The incubation with DQ-gelatin can be combined with simultaneous immunohistochemical detection of a protein on the same section. To draw valid conclusions from the findings with in situ zymography, specific inhibitors need to be used and the technique has to be combined with immunohistochemistry and zymography. In that case, in situ zymography provides data that extend our understanding of the role of specific proteinases in various physiological and pathological conditions.
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Affiliation(s)
- Wilma M Frederiks
- Academic Medical Center, University of Amsterdam, Department of Cell Biology and Histology, Amsterdam, The Netherlands.
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26
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Bailey SR, Marr CM, Elliott J. Current research and theories on the pathogenesis of acute laminitis in the horse. Vet J 2004; 167:129-42. [PMID: 14975387 DOI: 10.1016/s1090-0233(03)00120-5] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2003] [Indexed: 11/23/2022]
Abstract
A large number of studies have been undertaken in recent years aimed at furthering our understanding of the complex mechanisms underlying the common and debilitating condition of acute laminitis in the horse. Many of these studies have either reinforced or cast doubt on previously held theories on the pathogenesis of this disease, while others have suggested new mechanisms which may play a key role in its development. This review seeks to put the current hypotheses into the context of this recent body of evidence. While a unifying theory may not yet seem to be achievable, this review demonstrates that most of the current theories are not mutually exclusive. Studies utilising in vitro and in vivo models of the disease, particularly addressing the areas of inflammation, haemodynamic disturbances and enzyme activation in the hoof, as well as the preceding events occurring in the hindgut, have helped to explain many clinical observations of the disease and may possibly lead to more effective therapies and means of prevention in the future.
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Affiliation(s)
- Simon R Bailey
- Department of Veterinary Basic Sciences, Royal Veterinary College, North Mymms, Hatfield, Hertfordshire, UK
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27
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Loukopoulos P, Mungall BA, Straw RC, Thornton JR, Robinson WF. Matrix metalloproteinase-2 and -9 involvement in canine tumors. Vet Pathol 2003; 40:382-94. [PMID: 12824510 DOI: 10.1354/vp.40-4-382] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Matrix metalloproteinases (MMPs) are a family of enzymes implicated in the degradation and remodeling of extracellular matrix and in vascularization. They are also involved in pathologic processes such as tumor invasion and metastasis in experimental cancer models and in human malignancies. We used gelatin zymography and immunohistochemistry to determine whether MMP-2 and MMP-9 are present in canine tumors and normal tissues and whether MMP production correlates with clinicopathologic parameters of prognostic importance. High levels of pro-MMP-9, pro-MMP-2, and active MMP-2 were detected in most canine tumors. Significantly higher MMP levels were measured in canine tumors than in nontumors, malignancies had higher MMP levels than benign tumors, and sarcomas had higher active MMP-2 than carcinomas. Cartilaginous tumors produced higher MMP levels than did nonsarcomatous malignancies, benign tumors, and normal tissues, and significantly greater MMP-2 than osteosarcomas and fibrosarcomas. Pro-MMP-9 production correlated with the histologic grade of osteosarcomas. The 62-kd form of active MMP-2 was detected only in high-grade, p53-positive, metastatic malignancies. Zymography proved to be a sensitive and quantitative technique for the assessment of MMP presence but has the limitation of requiring fresh tissue; immunohistochemistry is qualitative and comparatively insensitive but could be of value in archival studies. MMP presence was shown in a range of canine tumors, and their link to tumor type and grade was demonstrated for the first time. This study will allow a substantially improved evaluation of veterinary cancer patients and provides baseline information necessary for the design of clinical trials targeting MMPs.
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Affiliation(s)
- P Loukopoulos
- School of Veterinary Science, The University of Queensland, Brisbane, Queensland 4072, Australia.
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28
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Yan SJ, Blomme EAG. In situ zymography: a molecular pathology technique to localize endogenous protease activity in tissue sections. Vet Pathol 2003; 40:227-36. [PMID: 12724562 DOI: 10.1354/vp.40-3-227] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Proteases play important roles in modulating a wide range of cellular functions, in the regulation of biologic processes, and in the pathogenesis of various diseases. Several molecular techniques are available to identify and characterize proteases in cells and tissues. Most of these techniques do not provide information on the activity of proteases in tissues. In situ zymography (ISZ) is a relatively low-cost technique that uses specific protease substrates to detect and localize specific protease activities in tissue sections. Used in combination with other techniques, ISZ provides data that further our understanding of the role of specific proteases in various pathologic and physiologic conditions. This review describes the general principle of ISZ and highlights the past and future applications of this technique in molecular pathology.
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Affiliation(s)
- S J Yan
- Experimental Pathology, Global Toxicology, Pharmacia Corporation, 4901 Searle Parkway, Skokie, IL 60077, USA
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29
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Kuwano A, Katayama Y, Kasashima Y, Okada K, Reilly JD. A gross and histopathological study of an ectopic white line development in equine laminitis. J Vet Med Sci 2002; 64:893-900. [PMID: 12419865 DOI: 10.1292/jvms.64.893] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In horses with chronic laminitis, an abnormal horny structure called lamellar wedge, is generated between the hoof wall and the laminar epidermis. To be able to manage horses with chronic laminitis correctly, more information about the pathological state of this abnormal horn is required. The aim of this study was to collect and analyze objective morphological data about the abnormal horn in order to understand its morphology and development. In the study, the abnormal horn was grossly visible on the sagittal hoof section from approximately 20 days after the onset of disease. In the histological observations, the structural characteristics of this abnormal horn were similar to the white line tissue, suggesting it is an ectopic white line. Mean value of the cross-sectional area of the abnormal horn against the distal phalanx section area (A/D) was 0.29 cm(2) SD +/- 0.14 and it finally showed an eight-fold increase over the mean value of normal white line section area against the distal phalanx section area. In conclusion, a large amount of the ectopic white line is thought to be finally able to inhibit normal hoof wall growth, so that it should be resected at the optimum time when would be after one month from the onset of the disease.
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Affiliation(s)
- Atsutoshi Kuwano
- Clinical Science & Pathobiology Division, Equine Research Institute, Japan Racing Association, Utsunomiya-shi, Tochigi, Japan
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30
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Mungall BA, Pollitt CC. In situ zymography: topographical considerations. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2001; 47:169-76. [PMID: 11245888 DOI: 10.1016/s0165-022x(00)00126-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In situ gelatin zymography is a simple technique providing valuable information about the cellular and tissue localization of gelatinases. Until recently, the use of this technique has been confined to soft, relatively homogeneous tissue. In this report in situ zymography has been utilized to assess the sub-lamellar location of gelatinases in the hard, semi-keratinized epidermal layer and the adjacent soft connective tissue matrix of the dermis of the equine hoof. We show that alterations in the orientation at which the tissue is dipped and withdrawn from the emulsion cause profound alterations in emulsion thickness. Microscopic variations in the surface topography of frozen tissue sections also influence emulsion thickness making interpretation of the results difficult. Given these results, researchers must be aware of potential variations in zymographic analysis may be influenced by physical tissue parameters in addition to suspected gelatinase activity.
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Affiliation(s)
- B A Mungall
- Department of Companion Animal Sciences, School of Veterinary Science, The University of Queensland, Queensland 4072, Brisbane, Australia
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31
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Crowther M, Goodall S, Jones JL, Bell PR, Thompson MM. Localization of matrix metalloproteinase 2 within the aneurysmal and normal aortic wall. Br J Surg 2000; 87:1391-400. [PMID: 11044166 DOI: 10.1046/j.1365-2168.2000.01554.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Current research has shed new light on the role of matrix metalloproteinase (MMP) 2 in the development of abdominal aortic aneurysms (AAAs). MMP-2 is a major protease in the wall of small aneurysms and is produced at increased levels by smooth muscle cells derived from AAAs compared with normal controls. In vivo, MMP-2 is produced as an inactive proenzyme that is activated predominantly by the cell membrane-bound enzyme, membrane type 1 matrix metalloproteinase (MT1-MMP). This study investigated the production of the MMP-2-MT1-MMP-tissue inhibitor of metalloproteinases (TIMP) 2 system within the wall of aortic aneurysms and in age-matched control arterial tissue. METHODS Arterial tissue from four patients with aortic aneurysms and four age-matched aortic samples was examined for the production and expression of MMP-2, TIMP-2 and MT1-MMP protein using immunohistochemistry, in situ hybridization and in situ zymography. RESULTS All components of the MMP-2-TIMP-2-MT1-MMP enzyme system were detected in the arterial wall of both aneurysm and control samples, specifically in the medial tissue. The enzymes co-localized with medial smooth muscle cells. Gelatinolytic activity was localized to elastin fibres in normal and aneurysmal aorta. CONCLUSION The presence of MT1-MMP within the media of arterial tissue suggests a powerful pathway for the activation of MMP-2. The localization of the MMP-2-TIMP-2-MT1-MMP enzyme system to the medial layer of the arterial wall gives support to the concept that this system may play an aetiological role in the pathogenesis of AAAs.
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Affiliation(s)
- M Crowther
- Departments of Surgery and Pathology, Clinical Sciences Building, Leicester Royal Infirmary, Leicester LE2 7LX, UK
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