Use of paclitaxel carried in solid lipid nanoparticles to prevent peritoneal fibrosis in rats.

BACKGROUND: Progressive fibrous thickening of peritoneal membrane (PM) is a major complication of long-term peritoneal dialysis. TGF-ß/SMAD pathway activation, inflammation and neoangiogenesis have an important role in PM changes induced by peritoneal dialysis. Here, we investigated the effects of paclitaxel (PTX) carried in lipid core nanoparticles (LDE) on the development of peritoneal fibrosis (PF) in rats. METHODS: To induce PF, 21 male Wistar rats (300-350g) were injected with chlorhexidine gluconate for 15 consecutive days and randomly assigned to three groups: 1)PF, n = 5: no treatment; 2)LDE, n = 8: treated with LDE only, 3/3 days during 15 days; 3)LDE-PTX, n = 8: treated with PTX (4mg/kg) associated with LDE, 3/3 days during 15 days. A Control group without PF induction (n = 5) was designed, received saline solution, 3/3 days. Peritoneum function tests were performed, and anterior abdominal wall samples of the PM were collected for analyses of peritoneal thickness, immunohistochemitry, and gene expression. RESULTS: LDE-PTX treatment preserved the membrane function, maintaining the ultrafiltration rate and mass transfer of glucose at normal levels. LDE-PTX also prevented PM thickening induced by chlorhexidine gluconate injections. LDE-PTX treatment reduced the number of myofibroblasts infiltrating PM and inhibited the cell proliferation. Gene expression of fibronectin, FSP-1, VEGF, TGF-ß, and SMAD3 were reduced by LDE-PTX. CONCLUSIONS: LDE-PTX was effective to prevent development of PF and preserve the PM filtration capacity in this rat model, with clear-cut actions on pro-fibrotic mechanisms. Thus, LDE-PTX can be candidate for future clinical trials as adjuvant to peritoneal dialysis to prevent PF development, since this preparation is devoid of toxicity as shown previously.

Use of paclitaxel carried in lipid nanoparticles to treat aortic allograft transplantation in rats.

OBJECTIVES: The aim of this study was to test whether lipid core nanoparticles loaded with paclitaxel (LDE-PTX) protect rat aortic allograft from immunological damage. METHODS: Fisher and Lewis rats were used differing in minor histocompatibility loci. Sixteen Lewis rats were allocated to four-animal groups: SYNG (syngeneic), Lewis rats receiving aorta grafts from Lewis rats; ALLO (allogeneic), Lewis rats receiving aortas from Fisher rats; ALLO+LDE (allogeneic transplant treated with LDE), Lewis rats receiving aortas from Fisher rats, treated with LDE (weekly injection for 3 weeks); ALLO+LDE-PTX (allogeneic transplant treated with LDE-PTX), Lewis rats receiving aortas from Fisher rats treated with LDE-PTX (4 mg/kg weekly for 3 weeks). Treatments began on transplantation day. RESULTS: Thirty days post-transplantation, SYNG showed intact aortas. ALLO and ALLO+LDE presented intense neointimal formation. In ALLO+LDE-PTX, treatment inhibited neointimal formation; narrowing of aortic lumen was prevented in ALLO and ALLO+LDE. LDE-PTX strongly inhibited proliferation and intimal invasion by smooth muscle cells, diminished 4-fold presence of apoptotic/dead cells in the intima, reduced the invasion of aorta by macrophages and T-cells and gene expression of pro-inflammatory tumour necrosis factor-alpha (TNFα), interferon gamma (IFNγ) and interleukin-1 beta (IL-1ß). CONCLUSIONS: LDE-PTX was effective in preventing the vasculopathy associated with rejection and may offer a potent therapeutic tool for post-transplantation.

Tamoxifen and bone morphogenic protein-7 modulate fibrosis and inflammation in the peritoneal fibrosis model developed in uremic rats.

BACKGROUND: Peritoneal fibrosis (PF) represents a long-term complication of peritoneal dialysis (PD), affecting peritoneal membrane (PM) integrity and function. Understanding the mechanisms underlying PF development in an uremic environment aiming alternative therapeutic strategies for treating this process is of great interest. The aim of this study was to analyze the effects of tamoxifen (TAM) and recombinant BMP7 (rBMP7) in an experimental model of PF developed in uremic rats. METHODS: To mimic the clinical situation of patients on long-term PD, a combo model, characterized by the combination of PF and CKD with severe uremia, was developed in Wistar rats. PF was induced by intraperitoneal (IP) injections of chlorhexidine gluconate (CG), and CKD was induced by an adenine-rich diet. Uremia was confirmed by severe hypertension, increased blood urea nitrogen (BUN> 120 mg/dL) and serum creatinine levels (> 2 mg/dL). Uremic rats with PF were treated with TAM (10 mg/Kg by gavage) or BMP7 (30 µg/Kg, IP). Animals were followed up for 30 days. RESULTS: CG administration in uremic rats induced a striking increase in PM thickness, neoangiogenesis, demonstrated by increased capillary density, and failure of ultrafiltration capacity. These morphological and functional changes were blocked by TAM or rBMP7 treatment. In parallel, TAM and rBMP7 significantly ameliorated the PM fibrotic response by reducing α-SMA, extracellular matrix proteins and TGF-ß expression. TAM or rBMP7 administration significantly inhibited peritoneal Smad3 expression in uremic rats with PF, prevented Smad3 phosphorylation, and induced a remarkable up-regulation of Smad7, an intracellular inhibitor of TGFß/Smad signaling, contributing to a negative modulation of profibrotic genes. Both treatments were also effective in reducing local inflammation, possibly by upregulating IκB-α expression in the PM of uremic rats with PF. In vitro experiments using primary peritoneal fibroblasts activated by TGF-ß confirmed the capacity of TAM or rBMP7 in blocking inflammatory mediators, such as IL-1ß expression. CONCLUSIONS: In conclusion, these findings indicate important roles of TGF-ß/Smad signaling in PF aggravated by uremia, providing data regarding potential therapeutic approaches with TAM or rBMP7 to block this process.

Anti-fibrotic effects of valproic acid in experimental peritoneal fibrosis.

BACKGROUND: Progressive fibrous thickening of the peritoneal membrane is a complication of long-term peritoneal dialysis (PD). TGF-ß/Smad pathway activation, inflammation, and neoangiogenesis play important roles in peritoneal membrane (PM) changes induced by PD. Recently, histone deacetilase inhibitors (HDACi) have shown anti-fibrotic and anti-inflammatory effects in different experimental models. These drugs prevent deacetylation of histones causing a loosen chromatin, which in turn induce the expression of some anti-fibrotic genes. In addition, acetylation may increase the activity of proteins involved in tissue fibrosis, such as Smad7. Here, we explored the effect of valproic acid (VPA), an HDACi, on the development of peritoneal fibrosis (PF) in rats. METHODS: PF was induced by daily intraperitoneal injections of 0.1% chlorhexidine gluconate (CG) for 15 consecutive days. Male Wistar rats (250-300 g) were divided into 3 groups: CONTROL, control rats receiving only vehicle; PF, peritoneal fibrosis induced in rats; PF+VPA, rats with PF treated with VPA (300 mg/kg/day by gavage). PF was assessed by Masson's trichrome staining. Inflammation and fibrosis-associated factors were assessed by immunohistochemistry, immunofluorescence, multiplex analysis, and qPCR. RESULTS: Treatment with VPA significantly reduced PM thickness and the expression of myofibroblasts, besides preventing loss of ultrafiltration capacity of the PM. The upregulation of profibrotic factors (TGF-ß, fibronectin, and Smad3) in the PF group was significantly ameliorated by VPA. VPA modulated the TGF/Smad pathway, inhibiting phosphorylated Smad3 expression and inducing an increased Smad7 expression in the FP+VPA group. The neoangiogenesis and the expression of proinflammatory cytokines (TNF-α, IL-1ß, MCP-1) observed in the PF group was significantly reduced by VPA. CONCLUSIONS: Our results indicate that VPA suppressed experimental PF through modulation of the TGF-ß/Smad pathway. Interestingly, VPA treatment induced a higher expression of antifibrotic factors, such as Smad7. These results suggest that VPA may represent a potential strategy for treating long term PD complications.

Valproic Acid Prevents Renal Dysfunction and Inflammation in the Ischemia-Reperfusion Injury Model.

Ischemia-reperfusion injury (IRI) is a major contributor to acute kidney injury (AKI). At present, there are no effective therapies to prevent AKI. The aim of this study was to analyse whether valproic acid (VPA), a histone deacetylase inhibitor with anti-inflammatory properties, prevents renal IRI. Male Wistar rats were divided into three groups: SHAM rats were subjected to a SHAM surgery, IRI rats underwent bilateral renal ischemia for 45 min, and IRI + VPA rats were treated with VPA at 300 mg/kg twice daily 2 days before bilateral IRI. Animals were euthanized at 48 hours after IRI. VPA attenuated renal dysfunction after ischemia, which was characterized by a decrease in BUN (mg/dL), serum creatinine (mg/dL), and FENa (%) in the IRI + VPA group (39 ± 11, 0.5 ± 0.05, and 0.5 ± 0.06, resp.) compared with the IRI group (145 ± 35, 2.7 ± 0.05, and 4.9 ± 1, resp.; p < 0.001). Additionally, significantly lower acute tubular necrosis grade and number of apoptotic cells were found in the IRI + VPA group compared to the IRI group (p < 0.001). Furthermore, VPA treatment reduced inflammatory cellular infiltration and expression of proinflammatory cytokines. These data suggest that VPA prevents the renal dysfunction and inflammation that is associated with renal IRI.