title: Methotrexate (MTX)-cIBR conjugate for targeting MTX to leukocytes: conjugate stability and in vivo efficacy in suppressing rheumatoid arthritis.
abstract: Methotrexate (MTX) has been used to treat rheumatoid arthritis at low doses and leukemia at high doses; however, this drug can produce severe side effects. Our hypothesis is that MTX side effects can be attenuated by directing the drug to the target cells (i.e., leukocytes) using (cyclo(1,12)PenPRGGSVLVTGC) peptide (cIBR). To test this hypothesis, MTX was conjugated to the N-terminus of cIBR peptide to give MTX-cIBR conjugate. MTX-cIBR (5.0 mg/kg) suppressed joint arthritis in adjuvant arthritis rats and prevented periarticular inflammation and bone resorption of the limb joints. In vitro, the toxicity of MTX-cIBR peptide against Molt-3 T cells was inhibited by anti-lymphocyte function-associated antigen-1 (LFA-1) antibody and cIBR peptide in a concentration-dependent manner, suggesting that the uptake of MTX-cIBR was partially mediated by LFA-1. Chemical stability studies indicated that MTX-cIBR was most stable at pH 6.0. The MTX portion of MTX-cIBR was unstable under acidic conditions, whereas the cIBR portion was unstable under basic conditions. In biological media, MTX-cIBR had short half lives in rat plasma (44 min) and homogenized rat heart tissue (38 min). This low plasma stability may contribute to the low in vivo efficacy of MTX-cIBR; therefore, there is a need to design a more stable conjugate to improve the in vivo efficacy.
authors.affiliation: Department of Pharmaceutical Chemistry, The University of Kansas, Simons Research Laboratories, Lawrence, Kansas 66047, USA.
authors.forename: Sumit
authors.initials: S
authors.lastname: Majumdar
authors.forename: Meagan E
authors.initials: ME
authors.lastname: Anderson
authors.forename: Christine R
authors.initials: CR
authors.lastname: Xu
authors.forename: Tatyana V
authors.initials: TV
authors.lastname: Yakovleva
authors.forename: Leo C
authors.initials: LC
authors.lastname: Gu
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Malefyt
authors.forename: Teruna J
authors.initials: TJ
authors.lastname: Siahaan
mesh_terms: D000818:Animals; D018501:Antirheumatic Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001169:Arthritis, Experimental / Q000139:chemically induced / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D001172:Arthritis, Rheumatoid / Q000139:chemically induced / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D045744:Cell Line, Tumor; D002626:Chemistry, Pharmaceutical; D004337:Drug Carriers; D004355:Drug Stability; D005620:Freund's Adjuvant; D006207:Half-Life; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D008727:Methotrexate / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D010456:Peptides, Cyclic / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D013601:T-Lymphocytes / Q000378:metabolism*; D013678:Technology, Pharmaceutical / Q000379:methods; D013997:Time Factors
chemical_list: D018501:Antirheumatic Agents; D004337:Drug Carriers; D016169:Lymphocyte Function-Associated Antigen-1; D010456:Peptides, Cyclic; C515000:cIBR peptide; D005620:Freund's Adjuvant; D008727:Methotrexate