Toll-like receptor 2 (TLR2) mediates activation of stress-activated MAP kinase p38.

Early events in the response of cells to lipopolysaccharide (LPS) include activation of NF-kappaB and stress-activated MAP kinase p38. Recent studies have shown that the human Toll-like receptor 2 (TLR2) mediates activation of NF-kappaB in response to commercial preparations of LPS (comLPS), membrane lipoproteins, and Gram-positive bacterial products. Here, we show that expression of TLR2 in human embryonic kidney 293 cells enabled p38 phosphorylation in response to comLPS, a synthetic bacterial lipoprotein, and B. subtilis. Activation of p38 was confirmed by an in vitro kinase assay using ATF2 as substrate and by an assay measuring activation of the downstream effector of p38, MAP kinase-activated protein kinase in cells. Thus, TLR2 initiated the signaling pathway for p38 in response to bacterial products.

Expression and characterization of the chemokine receptor CCR2B from rhesus monkey.

Species selectivity of chemokine receptor antagonists is a potential deterrent to making preclinical assessments in vivo. To determine if rhesus monkey disease models could support these assessments, we pharmacologically and functionally characterized recombinant rhesus CCR2B receptor. For these studies we obtained the CCR2B coding region by PCR from genomic rhesus DNA and expressed the receptor as stable transfectants in Chinese Hamster Ovary cells. The surface expression of recombinant rhesus CCR2B was detected by flow cytometry using a commercially available monoclonal anti-hCCR2B antibody. This antibody was used to detect rhCCR2B on monocytes in peripheral blood mononuclear cell preparations from rhesus whole blood. The recombinantly expressed CCR2B exhibited similar high affinity binding to the CCR2 chemokine ligands from rhesus and human 125I-rhMCP-1 (K(d)=433+/-14 pM) and 125I-hMCP-1 (K(d)=550+/-256 pM). In competition binding, the receptor exhibited selective high affinity binding to the monocyte chemoattractant protein (MCP) family chemokines with little affinity for most other members of the CC family of chemokines. One exception was eotaxin, a high affinity ligand for CCR3, which bound to rhesus CCR2B receptor (K(i)=1467+/-205 pM). Chemokines which exhibited binding affinity for the receptor were tested for their ability to induce intracellular calcium release. In these experiments the relative potencies of the MCP family of chemokines for rhCCR2B were similar to the observed binding affinities. In contrast, eotaxin was functionally inactive as an antagonist or agonist to this receptor. TAK-799 (N,N-dimethyl-N-[4-[[[2-(4-methylphenyl)-6,7-dihydro-5H-benzocyclohepten-8-yl]carbonyl]amino]benzyl]tetrahydro-2H-pyran-4-aminium chloride), a dual CCR2/CCR5 antagonist, demonstrated high affinity for the rhesus CCR2B in competition with 125I-hMCP-1 binding to the receptor (K(i)=0.5 nM) and also potently blocked the MCP-1 induced calcium mobilization mediated through the receptor.

Extended-release niacin/laropiprant lowers serum phosphorus concentrations in patients with type 2 diabetes.

BACKGROUND: Niacin compounds lower serum phosphorus concentrations in patients with end-stage renal disease. METHODOLOGY: We evaluated the impact of extended release niacin, given in fixed-dose combination with laropiprant, a specific inhibitor of prostaglandin-mediated, niacin-induced flushing, versus placebo, on serum phosphorus concentrations measured serially (at weeks 0, 4, 8, 12, 18, 24, 30, and 36) during a 36-week randomized, controlled trial. All subjects had a confirmed diagnosis of type 2 diabetes (n = 446 niacin/laropiprant; n = 339 placebo). Estimated glomerular filtration rate ranged from 36 to 184 mL/min/1.73 m(2), with n = 111 (14.1%) having a value <60 mL/min/1.73 m(2). Subjects received one tablet daily of extended-release niacin/laropiprant (1g niacin/ 20 mg laropiprant) for the first 4 weeks, and 2 tablets once daily, thereafter, or matched placebo. Niacin lowered serum phosphorus concentrations by 0.36 mg/dL (95% CI: -0.40, -0.31; P < .001), relative to placebo, from baseline values of 3.57 and 3.56 mg/dL in the niacin and placebo groups, respectively. Subgroup analyses revealed no evidence for phosphorus-lowering effect modification by these baseline variables: glomerular filtration rate <60 (n = 111;14.1%) vs ≥60 mL/min/m(2) (n = 674; 85.9%); phosphorus ≤3.5 mg/dL (n = 392; 49.9%) vs >3.5 mg/dL (n = 393; 50.1%); or prior statin use (n = 618; 78.7%) vs nonuse (n = 167; 21.3%). CONCLUSIONS AND IMPLICATIONS: These data confirm that niacin's phosphorus-lowering effects-which may have therapeutic implications for the management of hyperphosphatemia and possible prevention of cardiorenal outcomes in renal disease-extend across a broad spectrum of renal function in type 2 diabetics without stage 4 or 5 chronic kidney disease (a glomerular filtration rate ≥30 mL/min/1.73 m(2)).

Hypophosphatemic effect of niacin in patients without renal failure: a randomized trial.

BACKGROUND AND OBJECTIVES: Niacin administration lowers the marked hyperphosphatemia that is characteristic of renal failure. We examined whether niacin administration also reduces serum phosphorus concentrations in patients who have dyslipidemia and are free of advanced renal disease. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We performed a post hoc data analysis of serum phosphorus concentrations that had been determined serially (at baseline and weeks 4, 8, 12, 18, and 24) among 1547 patients who had dyslipidemia and were randomly assigned in a 3:2:1 ratio to treatment with extended release niacin (ERN; 1 g/d for 4 weeks and dose advanced to 2 g/d for 20 weeks) combined with the selective prostaglandin D2 receptor subtype 1 inhibitor laropiprant (L; n = 761), ERN alone (n = 518), or placebo (n = 268). RESULTS: Repeated measures analysis revealed that ERN-L treatment resulted in a net mean (95% confidence interval) serum phosphorus change comparing ERN-L with placebo treatment of -0.13 mmol/L (-0.15 to -0.13 mmol/L; -0.41 mg/dl [-0.46 to -0.37 mg/dl]). These results were consistent across the subgroups defined by estimated GFR of <60 or > or =60 ml/min per 1.73 m(2), a serum phosphorus of >1.13 mmol/L (3.5 mg/dl) versus < or =1.13 mmol/L (3.5 mg/dl), the presence of clinical diabetes, or concomitant statin use. CONCLUSIONS: We have provided definitive evidence that once-daily ERN-L treatment causes a sustained 0.13-mmol/L (0.4-mg/dl) reduction in serum phosphorus concentrations, approximately 10% from baseline, which is unaffected by estimated GFR ranging from 30 to > or =90 ml/min per 1.73 m(2) (i.e., stages 1 through 3 chronic kidney disease).

Discovery of 3,5-bis(trifluoromethyl)benzyl L-arylglycinamide based potent CCR2 antagonists.

Systematic modification of a screening lead yielded a class of potent glycinamide based CCR2 antagonists. The best compound (55, (2S)-N-[3,5-bis(trifluoromethyl)benzyl]-2-{[2-(1-piperidinyl)ethyl]amino}-2-(3-thienyl)acetamide) displayed good binding affinity (IC50=30 and 39 nM) toward human monocytes and CHO cell expressing human CCR2b, respectively. Functionally, it blocked MCP-1 (CCL2)-induced calcium mobilization (IC50=50 nM) and chemotaxis mediated through the CCR2 receptor (9.6 nM). It is selective against other chemokine receptors tested.

Integrated genomic and proteomic analyses of gene expression in Mammalian cells.

Using DNA microarrays together with quantitative proteomic techniques (ICAT reagents, two-dimensional DIGE, and MS), we evaluated the correlation of mRNA and protein levels in two hematopoietic cell lines representing distinct stages of myeloid differentiation, as well as in the livers of mice treated for different periods of time with three different peroxisome proliferative activated receptor agonists. We observe that the differential expression of mRNA (up or down) can capture at most 40% of the variation of protein expression. Although the overall pattern of protein expression is similar to that of mRNA expression, the incongruent expression between mRNAs and proteins emphasize the importance of posttranscriptional regulatory mechanisms in cellular development or perturbation that can be unveiled only through integrated analyses of both proteins and mRNAs.