Abstracts (complete list) - Wissenschaft Online

Shipra Gupta, Sebastian Rieder, Sylvia Escher, Aleksandra Heitland, Wolf-Georg
Forssmann, Jörn Elsner, Ulf Forssmann
Chemokine receptor-mediated intravascular inactivation of
leukocytes by a non-glycosaminoglycan(GAG)-binding variant
of NNY-CCL14.
Chemokines play an important role in the selective recruitment of leukocytes during
inflammation and immunosurveillance. Glycosaminoglycan (GAG) binding has been
shown to be essential for the in vivo activity of certain chemokines. NNY-CCL14 has
been proposed as a potential therapeutic compound acting as a CD26-resistant,
agonistic inactivator of CCR1, CCR3 and CCR5. In this study, a non-GAG-binding variant
of NNY-CCL14 was generated by mutating basic (B) amino acids to glycine or alanine
within the identified 49BBXB52 GAG-binding motif. This variant, NNY-CCL14(G50,A51),
does not bind to heparin in contrast to its precursor NNY-CCL14. Its biological activity
was tested on CCR1, CCR3 and CCR5 using stably transfected cell lines or leukocytes in
comparison with NNY-CCL14. NNY-CCL14(G50,A51) demonstrated a two-fold reduced
ability to activate CCR1, but internalization of CCR1 was not affected. Surprisingly, the
activity on human CCR3 was strongly reduced. The biological effects on human CCR5
remained totally unaffected. There was a marked decrease in chemotaxis of eosinophils
and monocytes in response to NNY-CCL14(G50,A51). In mice treated i.v. with NNY-
CCL14(G50, A51), a sustained in vivo down-modulation of CCR5 was observed over a
3h period.
This non-GAG-binding mutant NNY-CCL14(G50,A51) retains the potential to induce
receptor desensitization and internalization, but cannot be presented on the
endothelium via heparin binding sites. Thus, after injection, it is available in the
circulation distant from otherwise physiologically presented GAG-bound chemokines.
These properties suggest that, when administered systemically, this receptor agonist is
able to modulate leukocyte functions (i.e. receptor internalization) prior to their
interaction with other endothelium-bound chemokines expressed under pathophysiological
conditions such as allergic inflammation.
Financial support: DFG grant FO77/10-1