An optimized derivative of an endogenous CXCR4 antagonist prevents atopic dermatitis and airway inflammation
BackgroundAberrant CXCR4/CXCL12 signaling is involved in many pathophysiological processes including chronic inflammatory diseases. Thus, the chemokine receptor CXCR4 is a promising target for the therapy of inflammatory disorders, such as atopic dermatitis or allergic asthma. A natural fragment of serum albumin, named EPI-X4, has previous been identified as endogenous peptide antagonist and inverse agonist of CXCR4. The endogenous CXCR4 antagonist provides a promising basis for the development of improved analogues for the therapy of inflammatory diseases. ObjectiveTo increase the anti-CXCR4 activity of EPI-X4 and to evaluate the therapeutic potential of optimized analogs in mouse models of atopic dermatitis and asthma. MethodsMolecular docking analysis of the interaction of EPI-X4 with CXCR4 was performed to define critical interaction motifs and to rationally design analogs with increased activity. EPI-X4 derivatives were synthesized and CXCR4 binding and antagonizing activity determined in assays for antibody competition, inhibition of CXCR4-mediated HIV-1 infection, CXCL12-dependent Ca2+ mobilization, ERK and AKT phosphorylation and cell migration. Toxicity of peptides was evaluated in zebrafish embryos. The therapeutic efficacy of the lead peptide EPI-X4 JM#21 was determined in mouse models of atopic dermatitis and asthma. ResultsDocking analysis identified key interaction motifs of EPI-X4/CXCR4. Rational drug design allowed to increase the anti-CXCR4 activity of EPI-X4 and resulted in the generation of the lead analog JM#21, which bound CXCR4 and suppressed CXCR4-tropic HIV-1 infection more efficiently than the clinically approved small molecule CXCR4 antagonist AMD3100. JM#21 did not exert toxic effects in zebrafish embryos and efficiently prevented inflammation of the skin in a mouse model of atopic dermatitis. Moreover, EPI-X4 and its improved derivative suppressed allergen-induced infiltration of eosinophils and other immune cells into the airways of animals in an asthma mouse model. ConclusionThe rationally designed EPI-X4 derivative JM#21 is a potent antagonist of CXCR4 and the first CXCR4 inhibitor with therapeutic efficacy in atopic dermatitis. Further clinical development of this new class of CXCR4 antagonists for the therapy of atopic dermatitis, asthma and other CXCR4-associated diseases is highly warranted. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY