DHMEQ, a novel nuclear factor-kappaB inhibitor, induces selective depletion of alloreactive or phytohaemagglutinin-stimulated peripheral blood mononuclear cells, decreases production of T helper type 1 cytokines, and blocks maturation of dendritic cells.

Dehydroxymethylepoxyquinomicin (DHMEQ), a novel nuclear factor kappaB (NF-kappaB) inhibitor, has been shown to be active against variety types of solid tumours as well as haematological malignant cells. This study explored the anti-inflammatory effects of DHMEQ in vitro. DHMEQ inhibited the proliferation of phytohaemagglutinin (PHA)-stimulated or alloreactive peripheral blood mononuclear cells (PBMC) in mixed lymphocyte cultures as measured using a 3-(4,5-dimethylithiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay. In contrast, DHMEQ did not affect the viability of resting PBMC. In addition, real-time polymerase chain reaction showed that DHMEQ decreased PHA-stimulated expression of T helper type 1 (Th1) cytokines, including interleukin-2, interferon-gamma, and tumour necrosis factor alpha, in PBMC as well as Jurkat T-lymphoblastic leukaemia cells, and also decreased levels of p65 isoforms of NF-kappaB in the nucleus. Furthermore, we found that DHMEQ inhibited the endocytic capacity of dendritic cells (DCs) and down-regulated the expression of cell surface antigen CD40, suggesting that DHMEQ blocked the maturation as well as the function of DCs. Taken together, the results suggest that DHMEQ may be useful for treatment of inflammatory diseases, including graft-versus-host disease after allogenic haematopoietic stem cell transplantation.