Effect of glucose and heparin on mesangial alpha 1(IV)COLL and MMP-2/TIMP-2 mRNA expression

Matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in kidney disease

Matrix metalloproteinases (MMPs) are a group of zinc and calcium endopeptidases which cleave extracellular matrix (ECM) proteins. They are also involved in the degradation of cell surface components and regulate multiple cellular processes, cell to cell interactions, cell proliferation, and cell signaling pathways. MMPs function in close interaction with the endogenous tissue inhibitors of matrix metalloproteinases (TIMPs), both of which regulate cell turnover, modulate various growth factors, and participate in the progression of tissue fibrosis and apoptosis. The multiple roles of MMPs and TIMPs are continuously elucidated in kidney development and repair, as well as in a number of kidney diseases. This chapter focuses on the current findings of the significance of MMPs and TIMPs in a wide range of kidney diseases, whether they result from kidney tissue changes, hemodynamic alterations, tubular epithelial cell apoptosis, inflammation, or fibrosis. In addition, the potential use of these endopeptidases as biomarkers of renal dysfunction and as targets for therapeutic interventions to attenuate kidney disease are also explored in this review.

Glibenclamide induces collagen IV catabolism in high glucose-stimulated mesangial cells

We have shown the full prevention of mesangial expansion in insulin-deficient diabetic rats by treatment with clinically-relevant dosages of glibenclamide (Glib). Studies in mesangial cells (MCs) also demonstrated reduction in the high glucose (HG)-induced accumulation of collagens, proposing that this was due to increased catabolism. In the present study, we investigated the signaling pathways that may be implicated in Glib action. Rat primary MCs were exposed to HG for 8 weeks with or without Glib in therapeutic (0.01 μM) or supratherapeutic (1.0 μM) concentrations. We found that HG increased collagen IV protein accumulation and PAI-1 mRNA and protein expression, in association with decreased cAMP generating capacity and decreased PKA activity. Low Glib increased collagen IV mRNA but fully prevented collagen IV protein accumulation and PAI-1 overexpression while enhancing cAMP formation and PKA activity. MMP2 mRNA, protein expression and gelatinolytic activity were also enhanced. High Glib was, overall, ineffective. In conclusion, low dosage/concentration Glib prevents HG-induced collagen accumulation in MC by enhancing collagen catabolism in a cAMP-PKA-mediated PAI-1 inhibition.

Matrix metalloproteinase-2 (MMP-2) and membrane-type 1 MMP (MT1-MMP) affect the remodeling of glomerulosclerosis in diabetic OLETF rats

BACKGROUND

We reported previously that diabetic glomerular nodular-like lesions were formed during the reconstruction process of mesangiolysis. However, the precise mechanism has yet to be elucidated. Here, we investigated the roles of matrix metalloproteinase (MMP)-2, which is activated from proMMP-2 by membrane-type (MT)-MMP in the sclerotic and endothelial cell injury process of a type II diabetic model, Otsuka Long-Evans Tokushima Fatty (OLETF) rats.

METHODS

Monocrotaline (MCT) or saline only was injected three times every 4 weeks in 36-week-old OLETF rats and control Long-Evans Tokushima Otsuka rats. Glomerular expression and enzymatic activity of MMP-2 and MT1-MMP were assessed by immunohistochemistry, gelatin zymography of cultured glomerular supernatants, in situ enzymatic detection and reverse transcription-polymerase chain reaction.

RESULTS

Mesangial matrix increased in OLETF rats. In addition, mesangiolysis and nodular-like mesangial expansion were observed only in MCT-injected endothelial injured OLETF rats. MMP-2 and MT1-MMP proteins increased in the expanded mesangial lesions in OLETF rats. Gelatin zymography revealed an increase in 62-kDa activated MMP-2 in the culture supernatants of isolated glomeruli from OLETF rats. In situ enzymatic activity of MMP in the mesangial areas was also detected in 50-week-old MCT-injected OLETF rats.

CONCLUSION

These results suggest that MMP-2 and MT1-MMP are produced and activated in glomeruli through the progression of diabetic nephropathy and may have some effect on the remodeling of the glomerular matrix in diabetic nephropathy.

Chemically modified heparin inhibits mesangial cell proliferation induced by high glucose through interfering with the cell cycle

The aims of this study were to investigate whether chemically modified non-anticoagulation heparin derivate (Periodate-Oxidized/Borohydride-Reduced modified heparin (OR-heparin)) can inhibit high glucose-induced human mesangial cell proliferation and its influence on the cell cycle. OR-heparin with low anticoagulation activity inhibited high glucose-induced early proliferation in a dose-dependent manner. OR-heparin released high glucose-arrested mesangial cells at G(1) phase, and dose-dependently increased S phase. OR-heparin also inhibited high glucose-activated ERK1/2 phosphorylation, induced p27(Kip1) expression, and suppressed reactive oxygen species (ROS) accumulation in a dose-dependent manner. Our results suggest that OR-heparin releases high glucose-arrested cells on G(1) phase and inhibits high glucose-induced mesangial cell proliferation through blocking ERK1/2 phosphorylation and delaying S phase progression, which may be in correlation with OR-heparin suppressing ROS accumulation.

Effects of heparin on the production of homocysteine-induced extracellular matrix metalloproteinase-2 in cultured rat vascular smooth muscle cells

OBJECTIVE

To study the effects of heparin on the production of homocysteine-induced extracellular matrix metalloproteinase-2 (MMP-2) in cultured rat vascular smooth muscle cells.

METHODS

The effects of different homocysteine levels (0 micromol/L to 1000 micromol/L) on MMP-2 production and the effects of different heparin concentrations (0 microg/mL to 100 microg/mL) on homocysteine-induced MMP-2 in cultured rat vascular smooth muscle cells were examined using gelatin zymography and Western blotting. The changes in MMP-2 were further compared with various treatments for 24 h, 48 h and 72 h.

RESULTS

Homocysteine (50 micromol/L to 1000 micromol/L) increased the production of MMP-2 significantly in a dose-dependent manner. Increased production of MMP-2 induced by homocysteine was reduced by the extracellular addition of heparin in a dose-dependent manner. Production of MMP-2 with various treatment regimens for 72 h was greater than for 24 h and 48 h.

CONCLUSIONS

Extracellular addition of heparin decreased homocysteine-induced MMP-2 secretion. Data suggest a mechanism by which hyperhomocysteinemia is involved in the pathogenesis of coronary artery disease and demonstrate a beneficial effect of heparin on these conditions.

Effect of losartan on the mRNA expressions of MT3-MMP and TIMP-2 in diabetic kidneys

BACKGROUND AND OBJECTIVES

The renin-angiotensin system plays a critical role in circulatory homoeostasis. Evidence has emerged that suggests a pathologic role for angiotensin II in patients with kidney disease. Losartan is an antagonist of angiotensin II and blocks the angiotensin II type-1 receptor. Thus it may reduce proteinuria and delay the progression of renal disease in diabetic nephropathy. We investigated the effects of losartan on the mRNA expressions of membrane-type3 matrix metalloproteinases (MT3-MMP) and the tissue inhibitor of metalloproteinase-2 (TIMP-2) in diabetic kidneys in order to evaluate degradation and remodeling of the extracellular matrix.

METHODS

Male Wistar rats were divided into 3 groups. Group A was the control group containing healthy rats (n = 11), group B comprised diabetic rats without any therapy (n = 11), and group C consisted of diabetic rats treated with losartan (n = 9). 24-hr urine samples were collected in order to measure urinary albumin excretion (UAE). After a period of 18 weeks, the kidneys were extracted from all rats in order to measure the mRNA expressions of MT3-MMP, TIMP-2 and transforming growth factor-beta1 (TGF-beta1) by RT-PCR. We also examined the glomerular basement membrane thickening and the mesangial matrix (MM) density (MM area/mesangial area).

RESULTS

The expression of renal MT3-MMP mRNA in group B (1.37 +/- 0.96) was significantly higher than that in group A (0.75 +/- 0.34, p < 0.05), but also significantly higher than in group C (0.75 +/- 0.30, p < 0.05). Similarly, the mRNA expression of renal TIMP-2 in group B (0.73 +/- 0.37) was significantly increased compared to that in group A (0.32 +/- 0.19, p < 0.05), but also higher than in group C (0.34 +/- 0.17, p < 0.05). In addition, subjects in group B showed abundant TGF-beta1 mRNA expression and UAE compared to groups A and C, as well as significantly higher glomerular basement membrane thickening and MM density (all p < 0.05).

CONCLUSIONS

We conclude that MT3-MMP and TIMP-2 production in the renal cortex of diabetic kidneys is increased. Losartan can prevent the development of diabetic nephropathy by decreasing MT3-MMP and TIMP2 production in diabetic kidneys.

Role of angiotensin II in diabetic nephropathy

Considerable evidence suggests that the intrarenal renin-angiotensin system plays an important role in diabetic nephropathy. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (Ang II) receptor blockers (ARBs) can attenuate progressive glomerulosclerosis in disease models and can slow disease progression in humans. Because agents that interfere with Ang II action may decrease glomerular injury without altering glomerular pressures, it has been suggested that Ang II has direct effects on glomerular cells to induce sclerosis independent of its hemodynamic actions. To study nonhemodynamic effects of Ang II on matrix metabolism, many investigators have used cell culture systems. Glucose and Ang II have been shown to produce similar effects on renal cells in culture. For instance, incubation of mesangial cells in high-glucose media or in the presence of Ang II stimulates matrix protein synthesis and inhibits degradative enzyme (e.g., collagenase, plasmin) activity. Glucose and Ang II also can inhibit proximal tubule proteinases. Glucose increases expression of the angiotensinogen gene in proximal tubule cells and Ang II production in primary mesangial cell culture, which indicates that high glucose itself can activate the renin-angiotensin system. The effects of glucose and Ang II on mesangial matrix metabolism may be mediated by transforming growth factor-beta (TGF-beta). Exposure of mesangial cells to glucose or Ang II increases TGF-beta expression and secretion. Their effects on matrix metabolism can be blocked by anti-TGF-beta antibody or ARBs such as losartan, which also prevents the glucose-induced increment in TGF-beta secretion. Taken together, these findings support the hypothesis that the high-glucose milieu of diabetes increases Ang II production by renal, and especially, mesangial cells, which results in stimulation of TGF-beta secretion, leading to increased synthesis and decreased degradation of matrix proteins, thus producing matrix accumulation. This may be an important mechanism linking hyperglycemia and Ang II in the pathogenesis of diabetic nephropathy.

Pentosan polysulfate decreases proliferation and net extracellular matrix production in mouse mesangial cells

Glomerulosclerosis is characterized by extracellular matrix accumulation and is often associated with mesangial cell proliferation. Heparin-like molecules have been shown to decrease glomerulosclerosis in vivo, although their cellular site and mechanism of action is still unclear. In this study, a line of glomerular mesangial cells derived from normal mice was used to determine whether pentosan polysulfate (PPS) inhibited proliferation and altered extracellular matrix turnover. Cells treated with PPS showed a decrease in cell number beginning 24 h after treatment, which was maintained for 5 d. For matrix accumulation and degradation studies, cells were treated for 5 d and collagen types I and IV protein were measured by enzyme-linked immunosorbent assay as well as matrix metalloproteinases (MMP) measured by zymography. Collagen types 1 and type IV were significantly decreased in the media (P < 0.0001) and cell layer (P < 0.005) after treatment with PPS but not after treatment with heparin. By zymography, MMP-2 was significantly increased after treatment with PPS (P < 0.001) and heparin (P < 0.05). PPS and heparin also decreased MMP-9 (P < 0.001) after treatment. Reverse zymography showed the presence of tissue inhibitors of metalloproteinases (TIMP)-1 and -2 in control mesangial cells. Treatment with PPS and heparin increased TIMP-1. In addition, TIMP-3 was found in the medium of treated but not control cells. In conclusion, PPS alters extracellular matrix turnover through the induction of MMP-2 and alterations in the TIMP profile and may be useful in decreasing progressive glomerulosclerosis.