BACKGROUND: A major barrier to clinical xenotransplantation is preformed xenoreactive natural antibodies (XNA) found in higher primates which react to Galalpha(1,3)Gal (alpha-Gal) epitopes found on lower species. Accommodation of organs to xenogeneic recipients involves upregulation of cytoprotective genes and resistance to complement dependent cytotoxicity (CDC). METHODS: To develop methods of increasing these organ-protective effects, we established an in vitro CDC model utilizing human serum as the source of XNA and porcine endothelial cells (pEC) as targets. RESULTS: Using this system we demonstrated that downregulation of alpha-Gal epitopes by siRNA silencing of alpha1,3-galactosyltransferase (alpha-GT) led to marginal protection from CDC while alpha-Gal silencing combined with Griffonia simplicifolia isolectin B4 (GS-IB4), a lectin that specifically binds to alpha-Gal epitopes, led to complete protection. Interestingly, alpha-Gal silencing and GS-IB4 mediated effects were not associated with inhibition of XNA binding to cells, but with significant decreased E-selectin expression and cytoprotective gene HO-1 upregulation. PI3K inhibitor LY294002 could block the elevation of HO-1 protein expression and reverse the protective effect of alpha-Gal silencing and GS-IB4 against CDC. CONCLUSION: These data support the use of combination approaches targeting independent accommodation mechanisms to synergistically enhance donor organ survival in a xenogeneic setting.
BACKGROUND: A major barrier to clinical xenotransplantation is preformed xenoreactive natural antibodies (XNA) found in higher primates which react to Galalpha(1,3)Gal (alpha-Gal) epitopes found on lower species. Accommodation of organs to xenogeneic recipients involves upregulation of cytoprotective genes and resistance to complement dependent cytotoxicity (CDC). METHODS: To develop methods of increasing these organ-protective effects, we established an in vitro CDC model utilizing human serum as the source of XNA and porcine endothelial cells (pEC) as targets. RESULTS: Using this system we demonstrated that downregulation of alpha-Gal epitopes by siRNA silencing of alpha1,3-galactosyltransferase (alpha-GT) led to marginal protection from CDC while alpha-Gal silencing combined with Griffonia simplicifolia isolectin B4 (GS-IB4), a lectin that specifically binds to alpha-Gal epitopes, led to complete protection. Interestingly, alpha-Gal silencing and GS-IB4 mediated effects were not associated with inhibition of XNA binding to cells, but with significant decreased E-selectin expression and cytoprotective gene HO-1 upregulation. PI3K inhibitor LY294002 could block the elevation of HO-1 protein expression and reverse the protective effect of alpha-Gal silencing and GS-IB4 against CDC. CONCLUSION: These data support the use of combination approaches targeting independent accommodation mechanisms to synergistically enhance donor organ survival in a xenogeneic setting.
Authors: Soad M Saleh; Ranjit S Parhar; Reem S Al-Hejailan; Razan H Bakheet; Hala S Khaleel; Hanif G Khalak; Anason S Halees; Marya Z Zaidi; Brian F Meyer; Gisella P Yung; Jörg D Seebach; Walter Conca; Khalid S Khabar; Kate S Collison; Futwan A Al-Mohanna Journal: J Immunol Date: 2013-07-19 Impact factor: 5.422
Authors: Chi Zhang; Lu Wang; Shan Zhong; Xiao-Xiao Wang; Ying Xiang; Shi Chen; Gang Chen Journal: J Huazhong Univ Sci Technolog Med Sci Date: 2013-02-08
Authors: Hye-Jung Yeom; Ok Jae Koo; Jaeseok Yang; Bumrae Cho; Jong-Ik Hwang; Sol Ji Park; Sunghoon Hurh; Hwajung Kim; Eun Mi Lee; Han Ro; Jung Taek Kang; Su Jin Kim; Jae-Kyung Won; Philip J O'Connell; Hyunil Kim; Charles D Surh; Byeong-Chun Lee; Curie Ahn Journal: PLoS One Date: 2012-10-05 Impact factor: 3.240