Novel Anti-Inflammatory Peptides Based on Chemokine–Glycosaminoglycan Interactions Reduce Leukocyte Migration and Disease Severity in a Model of Rheumatoid Arthritis

Abstract

Inflammation is characterized by the infiltration of leukocytes from the circulation and into the inflamed area. Leukocytes are guided throughout this process by chemokines. These are basic proteins that interact with leukocytes to initiate their activation and extravasation via chemokine receptors. This is enabled through chemokine immobilization by glycosaminoglycans (GAGs) at the luminal endothelial surface of blood vessels. A specific stretch of basic amino acids on the chemokine, often at the C terminus, interacts with the negatively charged GAGs, which is considered an essential interaction for the chemokine function. Short-chain peptides based on this GAG-binding region of the chemokines CCL5, CXCL8, and CXCL12γ were synthesized using standard Fmoc chemistry. These peptides were found to bind to GAGs with high affinity, which translated into a reduction of leukocyte migration across a cultured human endothelial monolayer in response to chemokines. The leukocyte migration was inhibited upon removal of heparan sulfate from the endothelial surface and was found to reduce the ability of the chemokine and peptide to bind to endothelial cells in binding assays and to human rheumatoid arthritis tissue. The data suggest that the peptide competes with the wild-type chemokine for binding to GAGs such as HS and thereby reduces chemokine presentation and subsequent leukocyte migration. Furthermore, the lead peptide based on CXCL8 could reduce the disease severity and serum levels of the proinflammatory cytokine TNF-α in a murine Ag-induced arthritis model. Taken together, evidence is provided for interfering with the chemokine-GAG interaction as a relevant therapeutic approach.

Targeting Chemokine—Glycosaminoglycan Interactions to Inhibit Inflammation

“…Furthermore, the inflammation, cellular exudate and hyperplasia were decreased upon treatment with pCXCL8-1 aa . The peptide improved the arthritic score that is a measure of severity of disease in this mouse model (232). Martinez-Burgo et al synthesized three different peptides derived from CXCL8: a COOH-terminal peptide (54-72) (wild-type peptide), a peptide (54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66)(67)(68)(69)(70)(71)(72) where the glutamic acid residue at position 70 was replaced with a lysine residue (E70K peptide) and a scrambled peptide consisting of the same amino acids as peptide 1 in a random order.…”

“…This approach resulted in limited success with a number of compounds in clinical trials, but only two small molecule chemokine receptor antagonists on the market (for treatment of HIV and treatment of leukemia) (225)(226)(227). Since it is clear that also binding to GAGs is important for chemokine functioning in vivo, a few groups are investigating the inhibition of chemokine-GAG interactions (199,(228)(229)(230)(231)(232)(233).…”

“…Recently, two other groups reported the development of chemokine-derived GAG-binding peptides as well. McNaughton et al synthesized CCL5-, CXCL8-, and CXCL12γ-derived peptides based on the knowledge of their GAG-binding regions (232). The peptides display sequence identity with the chemokines they are derived from.…”

A C‐terminal CXCL8 peptide based on chemokine–glycosaminoglycan interactions reduces neutrophil adhesion and migration during inflammation

“…Also, it might be of interest to study potential peptide oligomerization, as it could further increase GAG binding . These strategies might facilitate the impairment of the chemokine‐mediated neutrophil recruitment to ameliorate the injury associated with neutrophil‐mediated inflammation, such as in ischaemia reperfusion injury during transplantation, or in rheumatoid arthritis …”

“…29,42,43,77,78 These strategies might facilitate the impairment of the chemokine-mediated neutrophil recruitment to ameliorate the injury associated with neutrophil-mediated inflammation, such as in ischaemia reperfusion injury during transplantation, or in rheumatoid arthritis. 79 Mice express only CXCL8 homologues, KC/CXCL1 and MIP-2/CXCL2. The human CXCL8 C-terminal peptide used (54-72 amino acids) shares 32% identity and 21% identity with murine homologues (within KC/CXCL1 and MIP-2/CXCL2), respectively.…”