ABSTRACT
The purpose of the study was to examine the potential of inhibition of cathepsin S as a treatment for autoimmune diseases. A highly selective cathepsin S inhibitor, CSI-75, was shown to upregulate levels of the cathepsin S substrate, invariant chain Lip10, in vitro as well as in vivo in C57Bl/6 mice after oral administration. Functional activity of the compound was shown by a reduction in the OVA-specific response of OVA-sensitized splenocytes from C57Bl/6 mice as well as from OVA-TCR transgenic mice (DO11.10). Since these studies revealed a selective suppression of the Th1 and Th17 cytokines causing a shift to Th2, CSI-75 was tested in the murine HC-gp39-immunization model. Indeed, CSI-75 specifically reduced the circulating HC-gp39-specific IgG2a in these mice indicating selective inhibition of the Th1 type of response in vivo. The importance of especially the Th1 and Th17 cell subsets in the pathology of autoimmune diseases, renders CatS inhibition a highly interesting potential therapeutic treatment of autoimmune diseases. Therefore, CSI-75 was tested in a murine model of multiple sclerosis (i.e. experimental autoimmune encephalomyelitis (EAE)) in a semi-therapeutic setting (ie. oral treatment after initial sensitization to antigen). Finally, in a murine model with features resembling rheumatoid arthritis (the collagen-induced arthritis (CIA) model), CSI-75 was tested in a therapeutic manner (after disease development). CSI-75 caused a significant reduction in disease score in both disease models, indicating a promising role for CatS inhibitors in the area of therapeutic treatments for autoimmune diseases.
Subject(s)
Autoimmune Diseases/drug therapy , Cathepsins/antagonists & inhibitors , Piperidines/therapeutic use , Protease Inhibitors/therapeutic use , Pyridines/therapeutic use , Administration, Oral , Animals , Antigen-Presenting Cells/drug effects , Arthritis, Experimental/drug therapy , Autoimmune Diseases/immunology , Encephalomyelitis, Autoimmune, Experimental/drug therapy , Female , Humans , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Inbred DBA , Piperidines/administration & dosage , Protease Inhibitors/administration & dosage , Pyridines/administration & dosage , Th1 Cells/physiologyABSTRACT
Based on the theoretical understanding of the in vivo lysosomotropism, by adjusting the pk(a) of basic nitrogen containing cathepsin S inhibitors, a set of compounds with pk(a) 6-8 were identified to have excellent cell based Lip10 activity, yet avoiding undesired sequestration in spleen.
Subject(s)
Cathepsins/antagonists & inhibitors , Nitrogen/chemistry , Protease Inhibitors/chemistry , Pyridines/chemistry , Animals , Cathepsins/metabolism , Mice , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacokinetics , Pyridines/chemical synthesis , Pyridines/pharmacokinetics , Rats , Rats, Sprague-DawleyABSTRACT
The trifluoromethylphenyl P2 motif from previously reported heteroarylnitrile series has been successfully applied for the design and synthesis of highly potent novel ketoamide-based cathepsin S inhibitors. The key in this process is the change of the torsion angle between the P2 phenyl ring and the attached secondary amide by adding a small Cl, F, or Me group at the 2-position.
Subject(s)
Aniline Compounds/chemical synthesis , Cathepsins/antagonists & inhibitors , Cysteine Proteinase Inhibitors/chemical synthesis , Amides/chemical synthesis , Amides/pharmacology , Aniline Compounds/pharmacology , Animals , Cysteine Proteinase Inhibitors/pharmacology , Fluorine , Humans , Ketones , Structure-Activity RelationshipABSTRACT
Starting from previously disclosed equally potent cathepsin K and S inhibitor 4-propyl-6-(3-trifluoromethylphenyl)pyrimidine-2-carbonitrile 1, a novel 2-phenyl-9H-purine-6-carbonitrile scaffold was identified to provide potent and selective cathepsin S inhibitors.
Subject(s)
Cathepsins/antagonists & inhibitors , Nitriles/chemistry , Protease Inhibitors/chemistry , Purines/chemistry , Catalytic Domain , Cathepsin K/antagonists & inhibitors , Cathepsin K/metabolism , Cathepsins/metabolism , Cell Line , Computer Simulation , Humans , Nitriles/chemical synthesis , Nitriles/pharmacology , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacology , Purines/chemical synthesis , Purines/pharmacology , Pyrimidines/chemistryABSTRACT
6-Phenyl-1H-imidazo[4,5-c]pyridine-4-carbonitrile analogues were identified as potent and selective cathepsin S inhibitor against both purified enzyme and in human JY cell based cellular assays. This core has a very stable thio-trapping nitrile war-head in comparison with the well reported pyrimidine-2-carbonitrile cysteine cathepsin inhibitors. Compound 47 is also very potent in in vivo mouse spleenic Lip10 accumulation assays.
Subject(s)
Cathepsins/antagonists & inhibitors , Nitriles/chemistry , Protease Inhibitors/chemistry , Pyridines/chemistry , Animals , Binding Sites , Cathepsins/metabolism , Cell Line , Crystallography, X-Ray , Humans , Mice , Nitriles/chemical synthesis , Nitriles/pharmacokinetics , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacokinetics , Pyridines/chemical synthesis , Pyridines/pharmacokinetics , Structure-Activity RelationshipABSTRACT
Using computer aided modelling studies, a new extended P2/S2 interaction was identified. This extended region can accommodate a variety of functional groups, such as aryls and basic amines. It was discovered that the N3 nitrogen of the pyrimidine-2-carbonitrile is critical for its cathepsin cysteine protease inhibition. N1 nitrogen also contributes to the inhibitory activity, but to a very limited degree. An 'in situ double activation' mechanism was proposed to explain these results.
Subject(s)
Cathepsins/antagonists & inhibitors , Nitriles/chemistry , Protease Inhibitors/chemistry , Pyrimidines/chemistry , Binding Sites , Cathepsins/metabolism , Computer Simulation , Humans , Models, Molecular , Nitriles/chemical synthesis , Nitriles/pharmacology , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacologyABSTRACT
Morphing structural features of HTS-derived chemotypes led to the discovery of novel 2-cyano-pyrimidine inhibitors of cathepsin K with good pharmacokinetic profiles, for example, compound 20 showed high catK potency (IC(50)=4nM), >580-fold selectivity over catL and catB, and oral bioavailability in the rat of 52%.
