Design and Biological Evaluation of Colchicine-CD44-Targeted Peptide Conjugate in an In Vitro Model of Crystal Induced Inflammation.

Khalid A Zoghebi,Khaled A Elsaid,Keykavous Parang,Emira Bousoik

doi:10.3390/molecules25010046

Khalid A Zoghebi, Khaled A Elsaid + Show 2 more

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https://doi.org/10.3390/molecules25010046

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Abstract

Gout is an inflammatory arthritis due to the joint deposition of monosodium urate (MSU) crystals. Phagocytosis of MSU crystals by tissue macrophages results in the generation of reactive oxygen species (ROS) and production of inflammatory cytokines and chemokines. Colchicine use in gout is limited by severe toxicity. CD44 is a transmembrane glycoprotein that is highly expressed in tissue macrophages and may be involved in gout pathogenesis. The P6 peptide is a 20-amino acid residue peptide that binds to CD44. We hypothesized that the conjugation of colchicine to the P6 peptide would reduce its off-target cytotoxicity while preserving its anti-inflammatory effect. A modified version of P6 peptide and colchicine-P6 peptide conjugate were synthesized using Fmoc/tBu solid-phase and solution-phase chemistry, respectively. A glutaryl amide was used as a linker. The P6 peptide was evaluated for its binding to CD44, association, and internalization by macrophages. Cytotoxic effects of P6 peptide, colchicine, and colchicine-P6 peptide on macrophages were compared and the inhibition of ROS generation and interleukin-8 (IL-8) secretion in MSU-stimulated macrophages treated with P6 peptide, colchicine, or colchicine-P6 peptide was studied. We confirmed that the P6 peptide binds to CD44 and its association and internalization by macrophages were CD44-dependent. Colchicine (1, 10, and 25 μM) demonstrated a significant cytotoxic effect on macrophages while the P6 peptide and colchicine-P6 peptide conjugate (1, 10 and 25 μM) did not alter the viability of the macrophages. The P6 peptide (10 and 25 μM) reduced ROS generation and IL-8 secretion mediated by a reduction in MSU phagocytosis by macrophages. The colchicine-P6 peptide significantly reduced ROS generation and IL-8 secretion compared to the P6 peptide alone at 1 and 10 μM concentrations. Conjugation of colchicine to the P6 peptide reduced the cytotoxic effect of colchicine while preserving its anti-inflammatory activity.

Highlights

Gout is a prevalent inflammatory arthritis due to the precipitation of serum uric acid into crystallized deposits of monosodium urate (MSU) crystals in and around the joint [1,2,3]
Modified P6 peptide H2 N-WYKGDKFLYLQNGIEAIADF-CO-NH2 in reverse order was assembled on a Fmoc Rink amide resin using Fmoc solid-phase synthesis starting with Fmoc-L-phenylalanine (Fmoc-Phe-OH)
We provided evidence supporting that cluster determinant-44 (CD44) expression is enhanced under conditions characteristic of gout and that the CD44 receptor is directly involved in initiating inflammation by MSU

Summary

Introduction

Gout is a prevalent inflammatory arthritis due to the precipitation of serum uric acid into crystallized deposits of monosodium urate (MSU) crystals in and around the joint [1,2,3]. Gout flares are characterized by acute episodes of intense pain, severe inflammation, and joint swelling, with the knee and metatarsophalangeal joints most frequently affected [1,3]. Management of acute gout flares remains suboptimal, and hospitalizations due to poorly. Treatment modalities of acute gout flares include the use of nonsteroidal anti-inflammatory drugs (NSAIDs), selective cycloxygenase-2 (COX2) enzyme inhibitors, colchicine, and corticosteroids [9,10]. The use of these agents is not without harm, given the comorbidities seen in older patients with gout [11,12,13]

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