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

Abstract

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 TGFβ/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. Electronic supplementary material The online version of this article (10.1186/s10020-019-0110-5) contains supplementary material, which is available to authorized users.

Adipose-Derived Mesenchymal Stem Cells Modulate Fibrosis and Inflammation in the Peritoneal Fibrosis Model Developed in Uremic Rats

“…All animal procedures were approved by the Research Ethics Committee of USP Faculty of Medicine (FMUSP-CAPPesq 029/2016) and were conducted in accordance with our institutional guidelines and with international regulations for manipulation and care of experimental animals. In order to mimic the clinical situation of patients on long-term PD, a combo model, characterized by the combination of PF and uremia, was employed in the present study [10]. Uremia was induced by an adenine-rich diet.…”

“…Additionally, clinical administration of antifibrotic drugs, such as tamoxifen, has been described in some patients as an attempt to abrogate peritoneal inflammation and fibrosis. However, these approaches are only partially effective [7,9,10]. Furthermore, experimental blockade of inflammation and TGF-β by the administration of valproic acid, tamoxifen, and bone morphogenetic protein-7 (BMP7) have shown positive effects in preventing PF progression in animal models.…”

“…Furthermore, experimental blockade of inflammation and TGF-β by the administration of valproic acid, tamoxifen, and bone morphogenetic protein-7 (BMP7) have shown positive effects in preventing PF progression in animal models. Nevertheless, further studies are required to confirm the efficiency and safety of these compounds [5,10].…”

Experimental models in peritoneal dialysis (Review)

“…Considering the technical aspects of the experiment, preparation cycle of the model and hemorrhage/infection risk during the preparation process, 5/6 nephrectomy is often the most suitable and is frequently used ( 25 , 29 , 45 , 46 ). Commonly used drug methods include adenine infusion ( 47 , 48 ) and adriamycin infusion ( 49 ). It is worth noting that different animal species have differences in model establishment.…”

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“…Total RNA was extracted from snap-frozen portions of kidney by the guanidinium isothiocyanate/phenol-chloroform extraction method. Gene expression of the cytokines IL-1β, TNF-α, IL-6, INF-γ, IL-4 and IL-10 was analyzed by Real time PCR as previously described [18]. The following PCR cycle profile was used: 10 min at 95°C, followed by 40 cycles of 15 sec at 95°C for denaturation, 20 sec at 60°C for combined annealing, and 10 sec at 72°C for extension.…”