CRBP-I in the renal tubulointerstitial compartment of healthy rats and rats with renal fibrosis

Inhibition of Renal Stellate Cell Activation Reduces Renal Fibrosis

Interstitial fibrosis is a common feature of chronic kidney disease, and platelet-derived growth factor receptor-β (PDGFR-β)-positive mesenchymal cells are reportedly the major source of scar-producing myofibroblasts. We had previously demonstrated that albumin and its derivative R-III (a retinol-binding protein-albumin domain III fusion protein) inhibited the transdifferentiation/activation of hepatic stellate cells (HSCs) to myofibroblasts and that R-III administration reduced liver fibrosis. In this study, we isolated cells (referred to as renal stellate cells, RSCs) from rat kidney tissues using the HSC isolation protocol and compared their morphological and biochemical characteristics with those of HSCs. RSCs shared many characteristics with HSCs, such as storage of vitamin A-containing lipid droplets and expression of HSC markers as well as pericyte markers. RSCs underwent spontaneous transdifferentiation into myofibroblasts in in vitro culture, which was inhibited by albumin expression or R-III treatment. We also evaluated the therapeutic effects of R-III in unilateral ureteral obstruction (UUO)-induced renal fibrosis in mice. Injected R-III localized predominantly in cytoglobin/stellate cell activation-associated protein (Cygb/STAP)-positive cells in the kidney and reduced renal fibrosis. These findings suggest that RSCs can be recognized as the renal counterparts of HSCs and that RSCs represent an attractive therapeutic target for anti-fibrotic therapy.

Effects of Losartan, Tempol, and Their Combination On Renal Nitric Oxide Synthases in the Animal Model of Chronic Kidney Disease

Down-regulation of nitric oxide synthase (NOS) and NO deficiency in the kidneys have been implicated in the pathogenesis of chronic kidney disease (CKD). In this study we examined the effects of losartan, tempol, and combined treatment on three NOS isoforms expressions, kidney NO content and NOS correlation with renal function and structure in the early stage of adriamycin (ADR)-induced CKD in spontaneously hypertensive rats (SHR). Rats were divided into control group, and four other groups which were treated with ADR and received vehicle, losartan (L, angiotensin II type 1 receptor blocker), tempol (T, redox-cycling nitroxide) or T+L treatment (by gavage) in a six-week study. Reduction of all NOS isoforms expressions were significantly improved by losartan or tempol, and correlated with proteinuria amelioration. Combined treatment induced down-regulation of constitutive NOS isoforms, whilst inducible NOS was up-regulated and followed by increased nitrite content and a significant decline in the glomerular filtration rate. Losartan or tempol prevented ADR-induced neoexpression of vimentin in the glomeruli and tubulointerstital areas, whereas de novo vimentin expression was still observed in the atrophic tubules and in the interstitial fibroblasts and myofibroblasts in combined treatment. It can be concluded that single treatments, contrary to combined, were effective in improving NO bioavailability and slowing down the progression of CKD.

Comparison of trichostatin A and valproic acid treatment regimens in a mouse model of kidney fibrosis

Histone deacetylase (HDAC) inhibitors are promising new compounds for the therapy of fibrotic diseases. In this study we compared the effect of two HDAC inhibitors, trichostatin A and valproic acid, in an experimental model of kidney fibrosis. In mice, doxorubicin (adriamycin) can cause nephropathy characterized by chronic proteinuria, glomerular damage and interstitial inflammation and fibrosis, as seen in human focal segmental glomerulosclerosis. Two treatment regimens were applied, treatment was either started prior to the doxorubicin insult or delayed until a significant degree of proteinuria and fibrosis was present. Pre-treatment of trichostatin A significantly hampered glomerulosclerosis and tubulointerstitial fibrosis, as did the pre-treatment with valproic acid. In contrast, the development of proteinuria was only completely inhibited in the pre-treated valproic acid group, and not in the pre-treated trichostatin A animals. In the postponed treatment with valproic acid, a complete resolution of established doxorubicin-induced proteinuria was achieved within three days, whereas trichostatin A could not correct proteinuria in such a treatment regimen. However, both postponed regimens have comparable efficacy in maintaining the kidney fibrosis to the level reached at the start of the treatments. Moreover, not only the process of fibrosis, but also renal inflammation was attenuated by both HDAC inhibitors. Our data confirm a role for HDACs in renal fibrogenesis and point towards a therapeutic potential for HDAC inhibitors. The effect on renal disease progression and manifestation can however be different for individual HDAC inhibitors.

HDAC inhibitors in experimental liver and kidney fibrosis

Histone deacetylase (HDAC) inhibitors have been extensively studied in experimental models of cancer, where their inhibition of deacetylation has been proven to regulate cell survival, proliferation, differentiation and apoptosis. This in turn has led to the use of a variety of HDAC inhibitors in clinical trials. In recent years the applicability of HDAC inhibitors in other areas of disease has been explored, including the treatment of fibrotic disorders. Impaired wound healing involves the continuous deposition and cross-linking of extracellular matrix governed by myofibroblasts leading to diseases such as liver and kidney fibrosis; both diseases have high unmet medical needs which are a burden on health budgets worldwide. We provide an overview of the potential use of HDAC inhibitors against liver and kidney fibrosis using the current understanding of these inhibitors in experimental animal models and in vitro models of fibrosis.

Valproic acid attenuates proteinuria and kidney injury

Inhibitors of histone deacetylase (HDAC) have anti-inflammatory and antifibrotic effects in several organs and tissues, but their effect on the progression of renal disease is unknown. Here, we studied the effect of valproic acid in adriamycin-induced nephropathy in mice. Administration of valproic acid before kidney injury prevented the development of proteinuria and the onset of glomerulosclerosis. Even after postponing treatment until the peak of adriamycin-induced proteinuria, valproic acid rapidly decreased the quantity of proteinuria and attenuated the progression of renal disease. Valproic acid abrogated the decrease in glomerular acetylation observed during adriamycin-induced nephropathy. Furthermore, valproic acid attenuated the significant upregulation of profibrotic and proinflammatory genes, the deposition of collagen, and the infiltration of macrophages into the kidney. Valproic acid decreased glomerular apoptosis and proliferation induced by adriamycin. Ultrastructural studies further supported the protective effect of valproic acid on podocytes in this model. Taken together, these data suggest that HDACs contribute to the pathogenesis of renal disease and that HDAC inhibitors may have therapeutic potential in CKD.

Immunohistochemical study of the phenotypic change of the mesenchymal cells during portal tract maturation in normal and fibrous (ductal plate malformation) fetal liver

Background

In adult liver, the mesenchymal cells, portal fibroblasts and vascular smooth muscle cells can transdifferentiate into myofibroblasts, and are involved in portal fibrosis. Differential expression of markers, such as alpha-smooth muscle actin (ASMA), h-caldesmon and cellular retinol-binding protein-1 allows their phenotypic discrimination. The aim of our study was to explore the phenotypic evolution of the mesenchymal cells during fetal development in normal liver and in liver with portal fibrosis secondary to ductal plate malformation in a series of Meckel-Gruber syndrome, autosomal recessive polycystic kidney disease and Ivemark's syndrome.

Results

At the early steps of the portal tract maturation, portal mesenchymal cells expressed only ASMA. During the maturation process, these cells were found condensed around the biliary and vascular structures. At the end of maturation process, only cells around vessels expressed ASMA and cells of the artery tunica media also expressed h-caldesmon. In contrast, ASMA positive cells persisted around the abnormal biliary ducts in fibrous livers.

Conclusion

As in adult liver, there is a phenotypic heterogeneity of the mesenchymal cells during fetal liver development. During portal tract maturation, myofibroblastic cells disappear in normal development but persist in fibrosis following ductal plate malformation.