Substance P blocks ethanol-induced hepatotoxicity

Substance P Hinders Bile Acid-Induced Hepatocellular Injury by Modulating Oxidative Stress and Inflammation

Liver failure is an outcome of chronic liver disease caused by steatohepatitis and cholestatic injury. This study examined substance P (SP) effect on liver injury due to cholestatic stress caused by excessive bile acid (BA) accumulation. Chenodeoxycholic acid (CDCA) was added to HepG2 cells to induce hepatic injury, and cellular alterations were observed within 8 h. After confirming BA-mediated cellular injury, SP was added, and its restorative effect was evaluated through cell viability, reactive oxygen species (ROS)/inflammatory cytokines/endothelial cell media expression, and adjacent liver sinusoidal endothelial cell (LSEC) function. CDCA treatment provoked ROS production, followed by IL-8 and ICAM-1 expression in hepatocytes within 8 h, which accelerated 24 h post-treatment. Caspase-3 signaling was activated, reducing cell viability and promoting alanine aminotransferase release. Interestingly, hepatocyte alteration by CDCA stress could affect LSEC activity by decreasing cell viability and disturbing tube-forming ability. In contrast, SP treatment reduced ROS production and blocked IL-8/ICAM-1 in CDCA-injured hepatocytes. SP treatment ameliorated the effect of CDCA on LSECs, preserving cell viability and function. Collectively, SP could protect hepatocytes and LSECs from BA-induced cellular stress, possibly by modulating oxidative stress and inflammation. These results suggest that SP can be used to treat BA-induced liver injury.

The redox modulatory effects of SP/NK1R system: Implications for oxidative stress-associated disorders

Oxidative stress which refers to redox imbalance with increased generation of reactive oxygen species (ROS) has been associated with the pathophysiology of diverse disease conditions. Recently, a close, yet not fully understood, relation between oxidative stress and neuropeptides, in particular, substance P (SP), has been reported in certain conditions. SP has been shown to affect the cellular redox environment through activation of neurokinin-1receptor (NK1R). It seems that SP/NK1R system and oxidative stress can act either synergistically or antagonistically in a context-dependent manner, thereby, influencing the pathology of various clinical disorders either destructively or protectively. Importantly, the interactions between oxidative stress and SP/NK1R system can be pharmacologically targeted. Therefore, a better understanding of the redox modulatory properties of SP/NK1R signaling will pave the way for identifying new therapeutic possibilities for attenuating oxidative stress-mediated damage. Towards this end, we performed a comprehensive search through PubMed/Medline and Scopus databases and discussed all related existing literature regarding the interplay between oxidative stress and SP/NK1R system as well as their implication in various clinical disorders, to provide a clear view and hence better management of oxidative damage.

Substance P, A Promising Therapeutic Target in Musculoskeletal Disorders

A large number of studies have focused on the role of substance P (SP) and the neurokinin-1 receptor (NK1R) in the pathogenesis of a variety of medical conditions. This review provides an overview of the role of the SP-NK1R pathway in the pathogenesis of musculoskeletal disorders and the evidence for its role as a therapeutic target for these disorders, which are major public health problems in most countries. To summarize, the brief involvement of SP may affect tendon healing in an acute injury setting. SP combined with an adequate conjugate can be a regenerative therapeutic option in osteoarthritis. The NK1R antagonist is a promising agent for tendinopathy, rheumatoid arthritis, and osteoarthritis. Research on the SP-NK1R pathway will be helpful for developing novel drugs for osteoporosis.

Substance-P prevents the cholestatic liver injury by regulating inflammatory responses

Substance-P (SP) is a neuropeptide that modulates immune responses and accelerates tissue repair in critical inflammatory disease. Liver fibrosis and cirrhosis are the ultimate outcomes of almost all chronic liver diseases caused by viral infection, steatohepatitis, autoimmune, and cholestatic injury. Despite the development of new drugs, liver transplantation is still the only fundamental treatment; thus, new therapeutic approaches to mitigate liver fibrosis and chronic inflammation are constantly being needed. The aim of this study was to examine the effect of SP on liver damage due to cholestatic stress. To induce cholestatic injury, common bile duct ligation (CBDL) was attempted, followed by systemic application of SP. SP treatment increased IL-10 and decreased TNF-α in serum with increasing levels of circulating regulatory T cells (Tregs) from the early stage of CBDL. Moreover, SP decreased CBDL-induced TGF-β1 expression in the circulation. This could create anti-inflammatory/anti-fibrotic environment under CBDL, which might ameliorate the progression of liver fibrosis in CBDL. Histological and molecular analysis revealed that SP treatment reduced ductular reaction, hepatic damage, and apoptotic hepatocytes, accompanied by diminishing type I collagen and upregulating MMP-9. These studies found that SP is a promising therapeutic candidate for immune-related liver disease as well as cholestatic liver disease, by providing hepatic protective effects via immune suppression.

Substance P enhances the therapeutic effect of MSCs by modulating their angiogenic potential

Bone marrow mesenchymal stem cell (MSC) therapy acts through multiple differentiations in damaged tissue or via secretion of paracrine factors, as demonstrated in various inflammatory and ischaemic diseases. However, long‐term ex vivo culture to obtain a sufficient number of cells in MSC transplantation leads to cellular senescence, deficiency of the paracrine potential, and loss of survival rate post‐transplantation. In this study, we evaluated whether supplementation of MSCs with substance P (SP) can improve their therapeutic potential. SP treatment elevated the secretion of paracrine/angiogenic factors, including VEGF, SDF‐1a and PDGF‐BB, from late passage MSCs in vitro. MSCs supplemented with SP accelerated epidermal/dermal regeneration and neovascularization and suppressed inflammation in vivo, compared to MSCs transplanted alone. Importantly, supplementation with SP enabled the incorporation of transplanted human MSCs into the host vasculature as pericytes via PDGF signalling, leading to the direct engagement of transplanted cells in compact vasculature formation. Our results showed that SP is capable of restoring the cellular potential of senescent stem cells, possibly by modulating the generation of paracrine factors from MSCs, which might accelerate MSC‐mediated tissue repair. Thus, SP is anticipated to be a potential beneficial agent in MSC therapy for inflammatory or ischaemic diseases and cutaneous wounds.