Inhibition of glycinamide ribonucleotide formyltransferase results in selective inhibition of macrophage cytokine secretion in vitro and in vivo efficacy in rat adjuvant arthritis.
OBJECTIVE
To determine the effects of a glycinamide ribonucleotide formyltransferase (GARFT) inhibitor on macrophage inflammatory processes and in vivo in rat adjuvant arthritis.


METHODS
GARFT inhibitors, LY309886 (6S-2',5'-thienyl-5, 10-dideazatetrahydrofolic acid) and LY329201 (R)-N-[[5-[2-(2-amino-1,4,5,6,7,8-hexahydro-4-oxopyrido[2,3-d]pyrimidin-6-yl)ethyl]-2-thienyl]carbonyl]-L-glutamatic acid disodium salt, were investigated in vitro and ex vivo on primary murine peritoneal macrophages and in the RAW macrophage cell line for both purine depletion and inhibition of LPS induced monokine secretion. In vivo efficacy following GARFT inhibition was evaluated in modified rat adjuvant arthritis.


RESULTS
LY309886 inhibited purine biosynthesis in the RAW cell line with an EC50 of 90 nM, an effect readily reversible with exogenous hypoxanthine. LY309886 and LY329201 also inhibited LPS induced TNF alpha and MIP1 alpha in these cells and in primary macrophages. A similar effect could be demonstrated ex vivo with mice dosed for two days with 3 mg/kg of LY329201. LY329201 as well as methotrexate demonstrated a dose dependent reduction in both paw and spleen weight and improved joint histology following 2 weeks of dosing in a rat adjuvant arthritis study.


CONCLUSIONS
These results suggest that GARFT inhibitors should be tested in the treatment of rheumatoid arthritis by considering their mechanism of action, here successfully tested on activated macrophages.
Chintalacharuvu
S
S
Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, Indiana 46285, USA.
Evans
G F
GF
Shih
C
C
Bryant
H U
HU
Sandusky
G E
GE
Zuckerman
S H
SH
D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D001169:Arthritis, Experimental / Q000188:drug therapy / Q000201:enzymology*; D002460:Cell Line / Q000187:drug effects / Q000378:metabolism; D054407:Chemokine CCL4; D004305:Dose-Response Relationship, Drug; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006614:Hindlimb / Q000187:drug effects / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D011917:Rats, Inbred Lew; D013763:Tetrahydrofolates / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
C105065:6R-2',5'-thienyl-5,10-dideazatetrahydrofolic acid; D054407:Chemokine CCL4; D004791:Enzyme Inhibitors; C505753:LY329201; D008070:Lipopolysaccharides; D019402:Macrophage Inflammatory Proteins; D013763:Tetrahydrofolates; D014409:Tumor Necrosis Factor-alpha; D018698:Glutamic Acid; D000255:Adenosine Triphosphate