Modulation of cellular S1P levels with a novel, potent and specific inhibitor of sphingosine kinase-1.

SphK (sphingosine kinase) is the major source of the bioactive lipid and GPCR (G-protein-coupled receptor) agonist S1P (sphingosine 1-phosphate). S1P promotes cell growth, survival and migration, and is a key regulator of lymphocyte trafficking. Inhibition of S1P signalling has been proposed as a strategy for treatment of inflammatory diseases and cancer.

High-throughput screening assay for sphingosine kinase inhibitors in whole blood using RapidFire® mass spectrometry.

To facilitate discovery of compounds modulating sphingosine-1-phosphate (S1P) signaling, the authors used high-throughput mass spectrometry technology to measure S1P formation in human whole blood. Since blood contains endogenous sphingosine (SPH) and S1P, mass spectrometry was chosen to detect the conversion of an exogenously added 17-carbon-long variant of sphingosine, C17SPH, into C17S1P. The authors developed procedures to achieve homogeneous mixing of whole blood in 384-well plates and for a method requiring minimal manipulations to extract S1P from blood in 96- and 384-well plates prior to analyses using the RapidFire(®) mass spectrometry system.

Cartilage degradation biomarkers predict efficacy of a novel, highly selective matrix metalloproteinase 13 inhibitor in a dog model of osteoarthritis: confirmation by multivariate analysis that modulation of type II collagen and aggrecan degradation peptides parallels pathologic changes.

Objective: To demonstrate that the novel highly selective matrix metalloproteinase 13 (MMP-13) inhibitor PF152 reduces joint lesions in adult dogs with osteoarthritis (OA) and decreases biomarkers of cartilage degradation.

Methods: The potency and selectivity of PF152 were evaluated in vitro using 16 MMPs, TACE, and ADAMTS-4 and ADAMTS-5, as well as ex vivo in human cartilage explants. In vivo effects were evaluated at 3 concentrations in mature beagles with partial medial meniscectomy.

Pharmacokinetic/pharmacodynamic (PK/PD) differentiation of native and PEGylated recombinant human growth hormone (rhGH and PEG-rhGH) in the rat model of osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease that has no FDA-approved treatment. The current standard of care does not address the regeneration of the damaged cartilage. Human growth hormone (hGH) is part of the insulin-like growth factor (IGF)-1 axis.

Design and validation of an immunoaffinity LC-MS/MS assay for the quantification of a collagen type II neoepitope peptide in human urine: application as a biomarker of osteoarthritis.

Biomarkers play an increasingly important role for drug efficacy and safety evaluation in all stages of drug development. It is especially important to develop and validate sensitive and selective biomarkers for diseases where the onset of the disease is very slow and/or the disease progression is hard to follow, i.e.

A novel autotaxin inhibitor reduces lysophosphatidic acid levels in plasma and the site of inflammation.

Autotaxin is the enzyme responsible for the production of lysophosphatidic acid (LPA) from lysophosphatidyl choline (LPC), and it is up-regulated in many inflammatory conditions, including but not limited to cancer, arthritis, and multiple sclerosis. LPA signaling causes angiogenesis, mitosis, cell proliferation, and cytokine secretion. Inhibition of autotaxin may have anti-inflammatory properties in a variety of diseases; however, this hypothesis has not been tested pharmacologically because of the lack of potent inhibitors.

Biochemical, cellular, and anti-inflammatory properties of a potent, selective, orally bioavailable benzamide inhibitor of Rho kinase activity.

Rho kinase, is the most widely studied downstream effector of the small Rho GTPase RhoA. Two Rho kinase isoforms have been described and are frequently referred to in the literature as ROCK1 and ROCK2. The RhoA-Rho kinase pathway has been implicated in the recruitment of cellular infiltrates to disease loci in a number of preclinical animal models of inflammatory disease.

Distinction of microsomal prostaglandin E synthase-1 (mPGES-1) inhibition from cyclooxygenase-2 inhibition in cells using a novel, selective mPGES-1 inhibitor.

Inflammation-induced microsomal prostaglandin E synthase-1 (mPGES-1) is the terminal enzyme that synthesizes prostaglandin E(2) (PGE(2)) downstream of cyclooxygenase-2 (COX-2). The efficacy of nonsteroidal anti-inflammatory drugs and COX-2 inhibitors in the treatment of the signs and symptoms of osteoarthritis, rheumatoid arthritis and inflammatory pain, largely attributed to the inhibition of PGE(2) synthesis, provides a rationale for exploring mPGES-1 inhibition as a potential novel therapy for these diseases. Toward this aim, we identified PF-9184 as a novel mPGES-1 inhibitor.

Discovery of (pyridin-4-yl)-2H-tetrazole as a novel scaffold to identify highly selective matrix metalloproteinase-13 inhibitors for the treatment of osteoarthritis.

Potent, highly selective and orally-bioavailable MMP-13 inhibitors have been identified based upon a (pyridin-4-yl)-2H-tetrazole scaffold. Co-crystal structure analysis revealed that the inhibitors bind at the S(1)(') active site pocket and are not ligands for the catalytic zinc atom. Compound 29b demonstrated reduction of cartilage degradation biomarker (TIINE) levels associated with cartilage protection in a preclinical rat osteoarthritis model.

ADAM-8 isolated from human osteoarthritic chondrocytes cleaves fibronectin at Ala(271).

Objective: Fibronectin fragments are thought to play a critical role in the initiation and progression of cartilage degradation in arthritis. In a recent study, fibronectin neoepitopes resulting from cleavage of intact fibronectin at the Ala(271)/Val(272) scissile bond, generating an approximately 30-kd fragment with the new C-terminus VRAA(271) and an approximately 50-85-kd fragment with the new N-terminus (272)VYQP, were identified in osteoarthritis (OA) cartilage. The present study was undertaken to isolate the enzymes responsible for this cleavage from human OA chondrocytes.

LC-MS/MS mediated absolute quantification and comparison of bile salt export pump and breast cancer resistance protein in livers and hepatocytes across species.

In the present study, capillary liquid chromatography (LC) nano electrospray ionization quadruple time-of-flight (nano-ESI-Q-TOF) mass spectrometry was utilized to identify the unique proteotypic peptides for liquid chromatography-tandem mass spectrometry (LC-MS/MS) mediated breast cancer resistance protein (BCRP/ABCG2) and bile salt export pump (BSEP/ABCG11) quantification, using insect membrane vesicles overexpressing the proteins. The lower limit of quantification was established to be 31.25 pM and 125 nM for BCRP/ABCG2 and BSEP/ABCG11, respectively.

Plasma 3-nitrotyrosine is a biomarker in animal models of arthritis: Pharmacological dissection of iNOS' role in disease.

The contribution of inducible nitric oxide synthase (iNOS) to oxidative/nitrative stress is well-documented in inflammation, but difficult to quantify. Using a novel, recently developed assay for 3-nitrotyrosine (3-NT), we characterized iNOS activity and its inhibition in preclinical models of inflammation. In particular, we utilized the 3-NT assay to assess the role of iNOS in the disease pathology as well as for proof of pharmacology of iNOS inhibitors in an acute endotoxin challenge model, in models of rheumatoid arthritis (RA) such as rat adjuvant- and collagen-induced arthritis (AIA and CIA) and a model of osteoarthritis (OA) such as rat sodium monoiodoacetate-induced arthritis (MIA).

Absolute quantification of multidrug resistance-associated protein 2 (MRP2/ABCC2) using liquid chromatography tandem mass spectrometry.

The multidrug resistance-associated protein 2 (MRP2/ABCC2) plays an important role in hepatobiliary efflux of many drugs and drug metabolites and has been reported to account for dramatic interspecies differences in the aspects of pharmacokinetics. In the present study, an absolute quantification method was developed to quantitatively measure MRP2/ABCC2 using LC-MS/MS for detection of a selective tryptic peptide. A unique 16-mer tryptic peptide was identified by conducting capillary LC nanospray ESI-Q-TOF analysis of the immunoprecipitation-enriched samples of MRP2/ABCC2 following proteolysis with trypsin.

Immunoaffinity liquid chromatography-tandem mass spectrometry detection of nitrotyrosine in biological fluids: development of a clinically translatable biomarker.

Measurement of nitrotyrosine levels in biological fluids can serve as a biomarker for oxidative/nitrative damage arising from formation of reactive nitrogen species, including peroxynitrite. Peroxynitrite is formed by the reaction of the superoxide radical (O2.-) with the nitric oxide radical (.

Clinical validation of an immunoaffinity LC-MS/MS assay for the quantification of a collagen type II neoepitope peptide: A biomarker of matrix metalloproteinase activity and osteoarthritis in human urine.

The degradation of type II collagen has been associated with the pathology of osteoarthritis (OA). Matrix metalloproteinases (MMPs) are enzymes that are responsible for catalyzing the degradation of collagen and, therefore, are pursued as potential targets for the treatment of OA. Collagen-derived peptides identified as a reflection of in vivo MMP activity have been investigated as target biomarkers of MMP activity as well as potential biomarkers of OA disease state and/or progression.

Identification of an ADAMTS-4 cleavage motif using phage display leads to the development of fluorogenic peptide substrates and reveals matrilin-3 as a novel substrate.

ADAMTS-4 and ADAMTS-5 are aggrecanases responsible for the breakdown of cartilage aggrecan in osteoarthritis. Multiple ADAMTS-4 cleavage sites have been described in several matrix proteins including aggrecan, versican, and brevican, but no concise predictive cleavage motif has been identified for this protease. By screening a 13-mer peptide library with a diversity of 10(8), we have identified the ADAMTS-4 cleavage motif E-(AFVLMY)-X(0,1)-(RK)-X(2,3)-(ST)-(VYIFWMLA), with Glu representing P1.

Unexpected fragmentation of beta-substituted meso-tetraphenylporphyrins induced by high-energy collisional activation.

The protonated molecules and radical cations of meso-tetraphenylporphyrins with beta-pyrrolic substituents, when formed by fast atom bombardment (FAB) and subjected to high-energy collisions, give rise to unexpected fragment ions. The reaction involves hydrogen migration from the ortho position of the phenyl ring to the a atom of the substituent, with formation of an intramolecular, six-membered ring. The process is analogous to condensed-phase cyclizations described for the same type of compounds.