Antirejection Effect of Herba Asari Extract in Rats After Cardiac Allograft Implantation

(-)-Asarinin alleviates gastric precancerous lesions by promoting mitochondrial ROS accumulation and inhibiting the STAT3 signaling pathway

BACKGROUND

(-)-Asarinin (Asarinin) is the primary component in the extract of the herb Asarum sieboldii Miq. It possesses various functions, including pain relief, anti-viral and anti-tuberculous bacilli effects, and inhibition of tumor growth. Gastric precancerous lesion (GPL) is a common but potentially carcinogenic chronic gastrointestinal disease, and its progression can lead to gastric dysfunction and cancer development. However, the protective effects of asarinin against GPL and the underlying mechanisms remain unexplored.

METHODS

A premalignant cell model (methylnitronitrosoguanidine-induced malignant transformation of human gastric epithelial cell strain, MC cells) and a GPL animal model were established and then were treated with asarinin. The cytotoxic effect of asarinin was assessed using a CCK8 assay. Detection of intracellular reactive oxygen species (ROS) using DCFH-DA. Apoptosis in MC cells was evaluated using an annexin V-FITC/PI assay. We performed western blot analysis and immunohistochemistry (IHC) to analyze relevant markers, investigating the in vitro and in vivo therapeutic effects of asarinin on GPL and its intrinsic mechanisms.

RESULTS

Our findings showed that asarinin inhibited MC cell proliferation, enhanced intracellular ROS levels, and induced cell apoptosis. Further investigations revealed that the pharmacological effects of asarinin on MC cells were blocked by the ROS scavenger N-acetylcysteine. IHC revealed a significant upregulation of phospho-signal transducer and activator of transcription 3 (p-STAT3) protein expression in human GPL tissues. In vitro, asarinin exerted its pro-apoptotic effects in MC cells by modulating the STAT3 signaling pathway. Agonists of STAT3 were able to abolish the effects of asarinin on MC cells. In vivo, asarinin induced ROS accumulation and inhibited the STAT3 pathway in gastric mucosa of mice, thereby halting and even reversing the development of GPL.

CONCLUSION

Asarinin induces apoptosis and delays the progression of GPL by promoting mitochondrial ROS production, decreasing mitochondrial membrane potential (MMP), and inhibiting the STAT3 pathway.

Asarinin inhibits immunological rejection via the Toll-like receptor-myeloid differentiation factor 88 signaling pathway in vitro

Asarinin has been found to prolong allograft survival and inhibit post-transplant immune rejection via the Toll-like receptor (TLR) signaling pathway. However, the underlying mechanism is not completely understood. Therefore, elucidating the possible pathophysiological role of asarinin in the TLR signaling pathway is essential. Here, dendritic cells were isolated from Sprague-Dawley® rats and cultured with splenocytes from Wistar rats treated with asarinin, lipopolysaccharide (LPS), and/or dimethyl sulfoxide. mRNA expression of TLR-2, TLR-4, myeloid differentiation factor 88 (MyD88), and nuclear factor kB (NF-kB) was determined using real-time polymerase chain reaction. Interleukin (IL)-6 and IL-12 levels were examined using an enzyme-linked immunosorbent assay. LPS resulted in an increase in the expression of TLR-2 rather than TLR-4 and MyD88. Furthermore, it inhibited the secretion of IL-6 and IL-12. MyD88 can be silenced after lentiviral transduction, and LPS can activate MyD88, whereas asarinin can inhibit this kind of activation. The effect of LPS and asarinin on TLR-4 could only be achieved when MyD88 was not silenced by lentivirus transduction. Therefore, asarinin might suppress TLR-4-mediated activation via the MyD88-dependent pathway. Overall, asarinin has a pre-application effect in inhibiting graft rejection.

A novel study on the immunomodulatory effect of umbilical cord derived mesenchymal stem cells pretreated with traditional Chinese medicine Asarinin

Allogeneic hematopoietic stem cell transplantation (HSCT) remains the key for the treatment of malignant hematological diseases, and acute graft-versus-host disease (aGVHD) that might occur after allogenic transplantation can be life threatening and promote disease recurrence. GVHD damages the various parts of the body by upregulating T helper 1 cytokines (Th1) cytokines and stimulating CD4、CD8 + T cells. GVHD can exhibit significant immunoregulatory effects, but could be easily affected by the mesenchymal stem cells (MSC) environment, and hence the MSC immunosuppressive effects on GVHD remain unpredictable. Hence, to better understand the role of MSC in the prevention and treatment of GVHD, umbilical cord derived mesenchymal stem cells (UC-MSC) were pre-treated with Chinese medicine Asarinin and IFN-γ. In the mix lymphocyte reaction, we found that Asarinin pre-treated UC-MSC can exert significantly greater inhibition towards the proliferation of CD4 and CD8 + T cells, down-regulate Th1 type cytokines, up-regulate Th2 type cytokines, and reduce the inflammatory damage to liver, lung and intestine of aGVHD mice model. Moreover, Asarinin can cooperate with IFN-γto promote UC-MSC to secrete indoleamine 2,3-dioxygenase (IDO). Our findings establish that Asarinin pre-treated UC-MSC can significantly promote the immunosuppressive effects of MSC on aGVHD after hematopoietic stem cell transplantation.