Human leukocytes regulate ganglioside expression in cultured micro-pig aortic endothelial cells

GM1 Induced the inflammatory response related to the Raf-1/MEK1/2/ERK1/2 pathway in co-culture of pig mesenchymal stem cells with RAW264.7

Pig-human xenotransplantation can trigger cell-mediated immune responses. We explored the role of gangliosides in inflammation related to immune rejection in xenotransplantation. Co-culture of xenogeneic cells (pig-MSCs and RAW264.7) was used to emulate xenotransplantation conditions. MTT assay results indicated that cell viability was significantly decreased in pADMSCs co-cultured with RAW264.7 cells. GM1 and GM3 were highly expressed in pADMSCs co-cultured with RAW264.7 cells. pADMSCs co-cultured with RAW264.7 cells strongly expressed pro-inflammatory proteins such as COX-2, iNOS, p50, p65, pIκBα, and TNF-α. GM1-knockdown pADMSCs co-cultured with RAW 264.7 cells did not show significantly altered cell viability, but pro-inflammatory proteins were markedly inhibited. Co-culture of pADMSCs with RAW264.7 cells induced significant phosphorylation (p) of JNK1/2 and pERK1/2. However, pERK1/2 and pJNK1/2 were decreased and MEK1/2 and Raf1 were suppressed in GM1-knockdown pADMSCs co-cultured with RAW264.7 cells. Thus, the Raf-1/MEK1/2/ERK1/2 and JNK1/2 pathways were significantly upregulated in response to increases of GM1 in co-cultured xenogeneic cells. However, the inflammatory response was suppressed in co-culture of GM1-knockdown pADMSCs with RAW264.7 cells via down-regulation of the Raf-1/MEK1/2/ERK1/2 and JNK1/2 pathways. Therefore, the ganglioside GM1 appears to play a major role in the inflammatory response in xenotransplantation via the Raf-1/MEK1/2/ERK1/2 and JNK1/2 pathways.

The current state of xenotransplantation

Pigs as a source of grafts for xenotransplantation can help to overcome the rapidly growing shortage of human donors. However, in the case of pig-to-human transplantation, the antibody-xenoantigen complexes lead to the complement activation and immediate hyperacute rejection. Methods eliminating hyperacute rejection (HAR) include α1,3-galactosyltransferase (GGTA1) inactivation, regulation of the complement system and modification of the oligosaccharide structure of surface proteins. The humoral immune response control and reduction of the risk of coagulation disorders are the priority tasks in attempts to overcome acute humoral xenograft rejection that may occur after the elimination of HAR. The primary targets for research are connected with the identification of obstacles and development of strategies to tackle them. Because of the magnitude of factors involved in the immune, genetic engineers face a serious problem of producing multitransgenic animals in the shortest possible time.