Participation of the matrix metalloproteinase inhibitor in Thy-1 nephritis

Matrix metalloproteinases in kidney homeostasis and diseases: an update

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases with important roles in kidney homeostasis and pathology. While capable of collectively degrading each component of the extracellular matrix, MMPs also degrade nonmatrix substrates to regulate inflammation, epithelial plasticity, proliferation, apoptosis, and angiogenesis. More recently, intriguing mechanisms that directly alter podocyte biology have been described. There is now irrefutable evidence for MMP dysregulation in many types of kidney disease including acute kidney injury, diabetic and hypertensive nephropathy, polycystic kidney disease, and Alport syndrome. This updated review will detail the complex biology of MMPs in kidney disease.

Matrix Metalloproteinases in Kidney Disease: Role in Pathogenesis and Potential as a Therapeutic Target

Matrix metalloproteinases (MMPs) are large family of proteinases. In addition to a fundamental role in the remodeling of the extracellular matrix, they also cleave a number of cell surface proteins and are involved in multiple cellular processes. MMP activity is regulated via numerous mechanisms, including inhibition by endogenous tissue inhibitors of metalloproteinases (TIMPs). Similar to MMPs, a role for TIMPs has been established in multiple cell signaling pathways. Aberrant expression of MMPs and TIMPS in renal pathophysiology has long been recognized, and with the generation of specific knockout mice, the mechanistic role of several MMPs and TIMPs is becoming more understood and has revealed both pathogenic and protective roles. This chapter will focus on the expression and localization of MMPs and TIMPs in the kidney, as well as summarizing the current information linking these proteins to acute kidney injury and chronic kidney disease. In addition, we will summarize studies suggesting that MMPs and TIMPs may be biomarkers of renal dysfunction and represent novel therapeutic targets to attenuate kidney disease.

TNFα enhances TLR3-dependent effects on MMP-9 expression in human mesangial cells

The role of MMPs (matrix metalloproteinases) in kidney diseases has been widely accepted, where they can regulate inflammatory response because of their effects on both recruitment and survival of inflammatory cells. TNFα (tumour necrosis factor α) has also been implicated in the pathogenesis of inflammatory kidney diseases, including forms of glomerulonephritis associated with viral diseases. Previously, we established the functional linkage between viral receptors of the innate immune system, the TLRs (Toll-like receptors) and control of MMP activity in human MC (mesangial cells). Expression levels of MMP-2, MMP-7, MMP-9, TIMP-1 (tissue inhibitor of metalloproteinase 1) and TIMP-2 in human MC in culture were analysed by RT-PCR (reverse transcription-PCR). TNFα significantly enhanced the TLR3-dependent induction of MMP-9 in human MC. Expression levels of MMP-2, TIMP-1 and TIMP-2 were not significantly affected by the activation of TLR3 or TNFα stimulation. No significant MMP-7 expression was found. We conclude that the role of MMP-9 in chemotaxis, activation and proliferation of inflammatory cells is amplified by TNFα originating from infiltrating cells, especially monocytes, producing a regulatory loop that potentially leads to a self-propagating inflammation.

Matrix metalloproteinases in kidney homeostasis and diseases

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that have been increasingly linked to both normal physiology and abnormal pathology in the kidney. Collectively able to degrade all components of the extracellular matrix, MMPs were originally thought to antagonize the development of fibrotic diseases solely through digestion of excessive matrix. However, increasing evidence has shown that MMPs play a wide variety of roles in regulating inflammation, epithelial-mesenchymal transition, cell proliferation, angiogenesis, and apoptosis. We now have robust evidence for MMP dysregulation in a multitude of renal diseases including acute kidney injury, diabetic nephropathy, glomerulonephritis, inherited kidney disease, and chronic allograft nephropathy. The goal of this review is to summarize current findings regarding the role of MMPs in kidney diseases as well as the mechanisms of action of this family of proteases.

Renoprotective action of a matrix metalloproteinase inhibitor in progressive mesangioproliferative nephritis

Background/Aim

Matrix metalloproteinases (MMPs) play pivotal roles in extracellular matrix turnover and are involved in chronic kidney disease. The renoprotective action of a synthetic MMP inhibitor, compound A, was investigated in chronic nephritis.

Methods

Nephritis was induced by a single injection of anti-Thy1.1 antibody to unilaterally nephrectomized rats. The effects of compound A on proteinuria, blood urea nitrogen, and matrix-related gene expressions were evaluated. Collagen accumulation, as assessed by periodic acid-Schiff staining and hydroxyproline content, was determined. The integrity of glomerular epithelial cells and glomerular basement membrane was evaluated with desmin immunohistochemistry and electron microscopic detection of anionic charge sites, respectively.

Results

Treatment with compound A notably attenuated proteinuria, ameliorated blood urea nitrogen, and prevented glomerulosclerosis. Gene upregulation of collagen and transforming growth factor β1 in the cortex was prevented in the treated animals. Glomerular epithelial cell injury was milder, and glomerular basement membrane anionic sites were protected with the treatment.

Conclusion

A novel MMP inhibitor, compound A, exerts protective effects in progressive glomerulonephritis. Compound A ameliorates various aspects of renal injuries and may have therapeutic potential toward kidney diseases.