Substance P Promotes Liver Sinusoidal Endothelium-Mediated Hepatic Regeneration by NO/HGF Regulation.

Liver sinusoidal endothelial cells (LSECs) are highly specialized and involved in hepatic regeneration by interacting with hepatic stellate cells (HSCs) and hepatocytes in a paracrine manner. However, hepatic injury can impair cellular activity and lead to endothelial dysfunction, eventually inducing the development of critical hepatic disease, including cirrhosis. Because LSECs exert their effects through paracrine factors, maintenance of paracrine potentials and survival activity in LSECs under injury stress is a critical strategy for inhibiting disease progression. This study explored the effect of Substance-P (SP) on cell viability, proliferation, and nitric oxide (NO)/hepatocyte growth factor (HGF) production in LSECs. Under noninjured conditions, SP treatment enhanced cell viability, cell proliferation, and HGF/NO secretion in LSECs. In the presence of tumor necrosis factor (TNF)-α-induced inflammatory stress, SP blocked TNF-α-induced endothelial dysfunction, accompanied by elevated cell viability and NO/HGF secretion. Interestingly, SP-primed LSEC-conditioned medium accelerated hepatocyte repopulation without causing morphological alterations. The primitive effect of SP was reversed by endothelial nitric oxide synthase inhibitor or HGF/c-MET inhibitor, indicating the importance of the NO/HGF combination in hepatic regeneration by SP. Taken together, these results suggest SP can protect LSECs from inflammatory stress by NO/HGF, which contributes to hepatocyte repopulation.

Substance P blocks ethanol-induced hepatotoxicity.

AIMS: Excessive alcohol consumption induces hepatic injury and promotes lipid accumulation, events involved in the pathogenesis of serious conditions such as alcoholic liver disease (ALD). Thus, protection of hepatocytes against alcohol-induced death is considered to be a critical approach to prevent development of liver disease. Substance P (SP) is capable of promoting cell proliferation and blocking cell death under diverse stresses, leading to beneficial effects in severe diseases, and is therefore likely to have a therapeutic application in hepatic injury. MAIN METHODS: To assess its effects on ethanol-induced hepatic damage in vitro and in vivo, SP was administered to ethanol-treated hepatocytes and a mouse model of this condition, respectively. The effect of SP was assessed based on cell viability, apoptosis, and Akt/GSK-3ß signaling, and mouse liver histology and serum biochemical parameters. KEY FINDINGS: SP was found to prevent hepatocyte death due to ethanol-induced oxidative stress by upregulating Akt/GSK-3ß activation in vitro. In vivo, ethanol treatment elevated levels of serum alanine transaminase and also increased the number of apoptotic cell, exhibiting lipid accumulation in liver tissue, effects that were entirely negated by SP treatment. Taken together, our results revealed that SP is able to block hepatic damage due to ethanol-induced oxidative stress and exerts therapeutic effects in liver disease, including ALD. Our findings identify SP treatment as a potential therapy for hepatic damage.

Substance P prevents development of proliferative vitreoretinopathy in mice by modulating TNF-α.

Purpose: Proliferative vitreoretinopathy (PVR) is an inflammatory fibrotic disease resulting from the inflammatory milieu after retinal detachment, which can prevent retinal healing. This study aimed to elucidate the effect of substance P (SP) on retinal degeneration caused by retinal detachment in vivo and to examine the role of SP in the tumor necrosis factor-alpha (TNF-α)-induced epithelial-mesenchymal transition (EMT) of human RPE cells in vitro. Methods: PVR-like retinal damage was induced by intravitreally injecting dispase into mice, and SP was systemically injected twice a week for 3 weeks. Histological analysis and cytokine profile with enzyme-linked immunosorbent assay (ELISA) were performed. The direct effect of SP on induction of EMT in vitro was studied by adding SP to TNF-α-treated ARPE-19 cells and then evaluating the change in the characteristics of the epithelial and mesenchymal cells. Results: Dispase injection led to a PVR-like retinal condition, demonstrating an inflammatory response with disruption of RPE interaction within 1 week and severe destruction with enfolding within 3 weeks after the dispase injection. The inflammatory environment promoted apoptosis and migration of fibroblast-like cells in the retinal layer, which can cause fibrotic disease, such as PVR. However, SP treatment suppressed early inflammatory responses by reducing TNF-α and elevating interleukin-10 (IL-10), with cell death and the appearance of fibroblastic cells inhibited and the progression of retinal degeneration obviously delayed. Moreover, SP ameliorated TNF-α-induced EMT of the RPE and directly prevented fibrotic change in the RPE. Conclusions: This study revealed that SP can block apoptosis and EMT due to retinal inflammation and inhibit the development of PVR. This effect most likely occurred by modulating the secretion and action of TNF-α..