Dermatan sulfate reduces monocyte chemoattractant protein 1 and TGF-β production, as well as macrophage recruitment and myofibroblast accumulation in mice with unilateral ureteral obstruction

Selectins play an essential role in most inflammatory reactions, mediating the initial leukocyte-rolling event on activated endothelium. Heparin and dermatan sulfate (DS) bind and block P- and L-selectin function in vitro. Recently, we reported that subcutaneous administration of DS inhibits colon inflammation in rats by reducing macrophage and T-cell recruitment and macrophage activation. In the present study, we examined the effect of porcine intestinal mucosa DS on renal inflammation and fibrosis in mice after unilateral ureteral obstruction (UUO). Twenty-four adult male Swiss mice weighing 20-25 g were divided into 4 groups: group C (N = 6) was not subjected to any surgical manipulation; group SH (N = 6) was subjected to surgical manipulation but without ureter ligation; group UUO (N = 6) was subjected to unilateral ureteral obstruction and received no treatment; group UUO plus DS (N = 6) was subjected to UUO and received DS (4 mg/kg) subcutaneously daily for 14 days. An immunoblot study was also performed for TGF-β. Collagen (stained area ~3700 µm(2)), MCP-1 (stained area ~1700 µm(2)), TGF-β (stained area ~13% of total area), macrophage (number of cells ~40), and myofibroblast (stained area ~1900 µm(2)) levels were significantly (P < 0.05) higher in the UUO group compared to control. DS treatment significantly (P < 0.05) reduced the content of collagen (stained area ~700 µm(2)), MCP-1 (stained area ~160 µm(2)) and TGF-β (stained area ~5% of total area), in addition to myofibroblast (stained area ~190 µm(2)) and macrophage (number of cells ~32) accumulation in the obstructed kidney. Overall, these results indicate that DS attenuates kidney inflammation by reducing macrophage recruitment, myofibroblast population and fibrosis in mice submitted to UUO.

Fucosylated chondroitin sulfate attenuates renal fibrosis in animals submitted to unilateral ureteral obstruction: a P-selectin-mediated event?

Fibrosis is the end point of most renal diseases, and several glycosaminoglycans have been shown to attenuate this process. Marine invertebrate glycosaminoglycans with unique structures have opened the possibility to test these new compounds on renal fibrosis. The effect of a fucosylated chondroitin sulfate from an echinoderm marine species is reported with the use of a model of renal fibrosis in rats, termed unilateral ureteral obstruction. Animals were given 4 mg/kg body wt of fucosylated chondroitin sulfate intraperitoneally, once a day. After 14 days, their kidneys were examined by histological, immunohistochemical, and biochemical methods. Compared with control mice, collagen deposition decreased in the course of renal fibrosis in the animals receiving fucosylated chondroitin sulfate, as revealed by Sirius red staining and hydroxyproline content. The cellularity related to myofibroblasts and macrophages was also reduced, as was the production of transforming growth factor (TGF)-β. The glycosaminoglycan content increased in the renal interstitium of animals submitted to unilateral ureteral obstruction compared with the control contralateral kidney, mostly due to an increase of chondroitin sulfate content. Interestingly, no change in the pattern of glycosaminoglycan deposition was observed after administration of fucosylated chondroitin sulfate. Fibrosis induced by unilateral ureteral obstruction is attenuated in P-selectin-deficient mice, which also do not respond to the invertebrate glycosaminoglycan. In conclusion, fucosylated chondroitin sulfate attenuates renal fibrosis on a ureteral obstruction model in mice preponderantly through a P-selectin-mediated mechanism.

The role of purinergic P2X7 receptors in the inflammation and fibrosis of unilateral ureteral obstruction in mice

Receptors of the P2X7 type have been demonstrated in granulocytes, monocytes/macrophages, B and T lymphocytes, and have been involved in several cellular mechanisms including those related to inflammation and immunological response. This study attempted to investigate the role of these receptors on the inflammatory and fibrogenic response in the kidneys of unilateral ureteral obstruction (UUO), by using P2X7 knockout mice (-/-). C57Bl6 mice were submitted to left UUO and killed after 7 and 14 days. Histopathology using hematoxylin-eosin, periodic-acid Schiff and Sirius-red staining, immunohistochemistry for macrophages, myofibroblasts, transforming growth factor-beta (TGF-beta)1 and P2X7, and immunofluorescence for apoptotic cells (terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick-end labeling) were performed. Protocols were as follows: (1) control; (2) sham; (3) control P2X7 (-/-); (4) sham P2X7 (-/-); (5) UUO wild type (WT); (6) UUO P2X7 (-/-). Myofibroblasts and Sirius-red staining were significantly lower in UUO P2X7 (-/-) mice at days 7 and 14, compared to UUO WT. Kidneys from UUO P2X7 (-/-) mice showed reduced number of inflammatory cells at day 14 but not at day 7, compared to UUO WT. TGF-beta1 was less in UUO P2X7 (-/-) mice at days 7 and 14 when compared to UUO WT. Macrophage infiltration and tubular apoptosis were lower in UUO P2X7 (-/-) at day 14 but not at day 7, compared to UUO WT. P2X7 was expressed only in tubular epithelial cells at day 7 of UUO WT mice. These findings constitute the first evidence that P2X7 receptors are implicated in macrophage infiltration, collagen deposition and apoptosis in response to ureteral obstruction in mice.

Effects of low molecular weight heparin in obstructed kidneys: decrease of collagen, fibronectin and TGF-β, and increase of chondroitin/dermatan sulfate proteoglycans and macrophage infiltration

BACKGROUND

Heparin exerts beneficial effects in different experimental models of nephropathy, as observed by the preservation of the structural morphology of the kidney after heparin therapy. Here we investigate molecular and cellular events involved in the protective effects of heparin in the progression of renal disease after unilateral ureteral obstruction.

METHODS

Thirty-six rats were divided into six groups: group C (control) was not subjected to any surgical manipulation; group S (sham) was subjected to surgical manipulation but without ureteral ligation; group UUO was subjected to ureteral obstruction and received no treatment; group UUO + S was subjected to ureteral obstruction and received saline subcutaneously (s.c.) once daily; group UUO + H was subjected to ureteral obstruction and received low molecular weight heparin (LMW-Hep; 4 mg/kg) s.c. once daily; and group C + H was not subjected to any surgical manipulation and received LMW-Hep (4 mg/kg) s.c. once daily. After 14 days, the content of collagen, fibronectin, total glycosaminoglycans (GAGS), chondroitin sulfate/dermatan sulfate proteoglycans (CS/DSPGs), transforming growth factor-beta (TGF-beta) and cellular infiltration were determined in the kidneys by immunohistochemical and biochemical techniques.

RESULTS

Collagen, fibronectin, total GAGS, CS/DSPGs, TGF-beta and cellular infiltration increased significantly in group UUO. LMW-Hep treatment reduced collagen, fibronectin and TGF-beta, but induced an increase in the content of total GAGS, CS/DSPGs and macrophage infiltration in group UUO + H when compared with group UUO.

CONCLUSIONS

LMW-Hep diminishes fibrosis in obstructed kidneys by downregulating the synthesis of collagen, fibronectin and TGF-beta. The mechanisms underlying the overproduction of CS/DSPGs and the increase in cellular infiltration upon LMW-Hep administration remain to be elucidated.

Effects of mycophenolate mofetil and lisinopril on collagen deposition in unilateral ureteral obstruction in rats

BACKGROUND/AIMS

Unilateral ureteral obstruction (UUO) in rats has been used as a model of renal interstitial fibrosis, in which therapeutic trials can be of important clinical relevance. In this study, we investigated the effects of mycophenolate mofetil (MMF), the angiotensin-converting enzyme (ACE) inhibitor lisinopril (L), and the combination of both drugs, given daily for 14 days to UUO rats, on the renal fibrogenic process triggered by UUO.

METHODS

Rats underwent surgical UUO, followed by treatment with daily doses of either MMF, lisinopril, or both, and were then sacrificed after 14 days. Kidney fragments were fixed for histopathological examination (hematoxylin-eosin and periodic acid-Schiff reactive) and immunohistochemistry for myofibroblasts (alpha-smooth muscle actin; alpha-SMA) and macrophages (ED-1). Histomorphometrical analysis of collagen was performed with Sirius red staining, and collagen content was assessed by the amount of hydroxyproline. Cortex and medulla were analyzed separately.

RESULTS

MMF, lisinopril and MMF+L reduced the density of alpha-SMA- and ED-1-positive cells (p < 0.05), interstitial volume (p < 0.05) and decreased Sirius-red-stained areas by 54.6, 35.6 and 58.0%, and hydroxyproline content by 60.1, 49.7 and 62.7%, respectively. No differences were observed among treated groups.

CONCLUSION

MMF and the ACE inhibitor lisinopril attenuated the progression of the fibrogenic process of UUO in an equivalent manner. The combination of both drugs did not add any further improvement in the collagen content.