Synergistic effect of combined double-stranded RNA and imiquimod stimulation / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the effect of combined double-stranded RNA (dsRNA) and imiquimod stimulation on uterine immune cells. Methods In BALB/c × C57BL/6 mice and non-obese dia-betic (NOD) × C57BI/6 mice, embryo resorption rate was detected in the presence or absence of Toll-like receptor 3 (TLR3) agonist dsRNA [poly( 1 C)], TLR7 agonist imiquimod ( R837), or their combination, respectively. In in vivo system, the status of intracellular cytokine production in uterine CD45 + cells was de-tected by flow cytometry. To identify the CD45 + cells, uterine CD3+ T cells and CD49b + NK cells derived from placenta and decidua basalis were stimulated with dsRNA and imiquimod in in vitro systems, and the status of intracellular cytokine production was detected. Mitogen-activated protein kinase (MAPK) antago- nists SP600125 and PD98059 were used to block the increase of cytokine production. Results A synergistic increase of embryo resorption was observed after the induction of dsRNA and imiquimod combination. Mean-while, a synergistic increase of TNF-α and IFN-γ production was detected after the induction in CD45 + cells. Further study found that although synergistic effect can be detected in both CD3 + cells and CD49b + cells in BALB/c mice, the status was different in NOD mice. The cytokine increase should mainly be attrib-uted to CD3 + T cells, since no such increase was detected among the CD49b + NK cells in the NOD mice. The synergistic effect of combined agonists was partially inhibited by Jun N-terminal kinase (JNK) MAPK inhibitor SP600125 and almost completely abrogated by extracellular signal-regulated kinase (ERK) MAPK inhibitor PD98059. Conclusion Boosted TLR3 and TLR7 signal may be transmitted via Thl-type T cells, rather than NK cells in NOD mice. ERK MAPK pathway may be critical in TLR3 and TLR7 involved signa- ling.