Protosappanin A as one major and effective ingredient from Caesalpinia sappan L. exhibited antirejection activity obviously in heart-transplanted rat. The present study was designed to screen out the potential target genes of
protosappanin A with microarray technology and reveal some molecular mechanism of immunosuppressive effect. Rats performed with ectopic peritoneal
heart transplantation were randomized into three groups receiving different treatments for 7 days:
protosappanin A group (25 mg kg(-1)),
cyclosporine A group (10 mg kg(-1)), and control group. The differentially expressed genes responding to
protosappanin A were analyzed with microarrays. Among common differentially expressed genes, the ones of interest were selected for further evaluation by real-time quantitative
reverse transcriptase polymerase chain reaction (qRT-PCR), Western blot, immunochemistry, immunofluorescence, and ELISA. Among the 146 common differentially expressed genes,
NF-kappaB and related genes like IkappaBa, IFN-r, and IP10 were selected for verification. The results of qRT-PCR, Western blot, immunochemistry, and ELISA showed that
protosappanin A significantly reduced the expression of
NF-kappaB, IFN-r, and IP10 (p < 0.05) and increased IkappaBa expression (p < 0.05) in graft. Moreover, the immunochemistry staining of
NF-kappaB and IkappaBa was mainly observed in infiltrating mononuclear cells. Strikingly, immunofluorescent staining localized
NF-kappaB to the TCR-positive T cells in graft. Furthermore,
protosappanin A exhibited inhibitory effect on T cell proliferation in recipients after 7-day treatment. In conclusion,
protosappanin A might act on T cells through inhibiting
NF-kappaB activation and downstream gene expressions of IFN-r and IP10, meanwhile reducing T cell proliferation responding to
alloantigen, so as to induce immunosuppressive effect. The results encourage a potential therapeutic evaluation of
protosappanin A for clinical
organ transplantation or other T cell-mediated
immune disorders. Additionally, our study also verified the feasibility of microarray utilization in Chinese herb research to explore molecular mechanism and promote development of scientific theories.