The effects of NF-κB inhibition by a NEMO binding domain peptide in vitro and in vivo

Objective

Dendritic cells (DC) are thought to play an important role in the pathogenesis of rheumatoid arthritis (RA). In RA, fully matured APC are present in the inflamed synovial tissue clustered around activated T cells. Because DC maturation and cytokine production are NF-κB dependent, we hypothesized that blocking NF-κB activity in DC by selectively targeting IKKβ with a specific NEMO binding domain (NBD) peptide could inhibit the maturation of DC and thereby modulate the immune response.

Methods

Immature DC were obtained by culturing freshly isolated monocytes in the presence of GM-CSF and IL-4. On day 6 immature DC were incubated with the NBD peptide (WT versus MUT) in the presence of maturation factors. DC were analyzed for NF-κB activity, surface marker expression, cytokine production and interaction with naive T cells. Furthermore, we investigated the effect of ia injection of the NBD peptide in adjuvant arthritis in rats.

Results

NF-κB blockade by the NBD peptide resulted in strongly reduced maturation of DC. In addition, IL-6, IL-12 and TNF-α production was dose dependently blocked. Interestingly, NBD peptide treatment resulted in increased CCR7 expression. Coculture with naïve T cells resulted in reduced proliferation and differentiation. In vivo, injection of the NBD peptide resulted in reduced paw swelling in arthritic rats.

Conclusions

Inhibiting NF-κB with the NBD peptide in DC results in an immature phenotype with increased CCR7 expression. The enhanced CCR7 expression may promote migration to draining lymph nodes and presentation of antigen in the absence of costimulation. These data strongly suggest that targeting NF-κB in DC could be beneficial in the treatment of arthritis, which is supported by preliminary data in rat adjuvant arthritis.