Analysis of binding site for the novel small-molecule TLR4 signal transduction inhibitor TAK-242 and its therapeutic effect on mouse sepsis model

BACKGROUND AND PURPOSE

TAK-242, a novel synthetic small-molecule, suppresses production of multiple cytokines by inhibiting Toll-like receptor (TLR) 4 signalling. In this study, we investigated the target molecule of TAK-242 and examined its therapeutic effect in a mouse sepsis model.

EXPERIMENTAL APPROACH

Binding assay with [(3)H]-TAK-242 and nuclear factor-kappaB reporter assay were used to identify the target molecule and binding site of TAK-242. Bacillus calmette guerin (BCG)-primed mouse sepsis model using live Escherichia coli was used to estimate the efficacy of TAK-242 in sepsis.

KEY RESULTS

TAK-242 strongly bound to TLR4, but binding to TLR2, 3, 5, 9, TLR-related adaptor molecules and MD-2 was either not observed or marginal. Mutational analysis using TLR4 mutants indicated that TAK-242 inhibits TLR4 signalling by binding to Cys747 in the intracellular domain of TLR4. TAK-242 inhibited MyD88-independent pathway as well as MyD88-dependent pathway and its inhibitory effect was largely unaffected by lipopolysaccharide (LPS) concentration and types of TLR4 ligands. TAK-242 had no effect on the LPS-induced conformational change of TLR4-MD-2 and TLR4 homodimerization. In mouse sepsis model, although TAK-242 alone did not affect bacterial counts in blood, if co-administered with ceftazidime it inhibited the increases in serum cytokine levels and improved survival of mice.

CONCLUSIONS AND IMPLICATIONS

TAK-242 suppressed TLR4 signalling by binding directly to a specific amino acid Cys747 in the intracellular domain of TLR4. When co-administered with antibiotics, TAK-242 showed potent therapeutic effects in an E. coli-induced sepsis model using BCG-primed mice. Thus, TAK-242 may be a promising therapeutic agent for sepsis.

[Hydrostatic weighing, skinfold thickness, body mass index relationships in high school girls]

A study was conducted to evaluate body composition by hydrostatic weighing, skinfold thickness, and body mass index (BMI) in 102 senior high school girls, aged 15 to 18 in Nagasaki City. Body density measured by the underwater weighing method, was used to determine the fat weight (Fat) and lean body mass (LBM. or fat free weight: FFW) utilizing the formulas by Brozek et al. The results were as follows; 1. Mean values of body density were 1.04428 in the first grade girls, 1.04182 in the second grade, and 1.04185 in the third grade. 2. Mean values of percentage body fat (%Fat) were 23.5% in the first grade, 24.5% in the second and 24.5% in the third. 3. Percentage body fat (%Fat), lean body mass (LBM) and LBM/Height were not significantly with different advance of grade from the first to the third. 4. The correlation coefficients between percent body fat and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.78, 0.79, and 0.80 respectively and were all statistically significant (p < 0.001). 5. The correlation coefficients between BMI and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.74, 0.74, and 0.74 respectively and were all statistically significant (p < 0.001). 6. Mean values of BMI, Rohrer index and waist-hip ratio (WHR) in all subjects (n = 102) were 20.3, 128.2 and 0.72 respectively.

[Body density assessment utilizing skinfold thickness and age in Japanese men]

A study was conducted to investigate the validity of skinfold-based prediction equations for body density (g/ml) by Nagamine and Suzuki (1964), and to formulate more convenient and more useful equations for predicting body density from skinfold and age in men. Subjects of the study were 257 healthy men aged 19-60 years in or near Nagasaki City. The regression equation for the dependent variable, body density, was determined by hydrostatic weighing. Independent variables included eight skinfolds, the sum of two skinfolds (triceps, subscapular), the sum of three skinfolds (triceps, subscapular, and abdominal), age, and body surface area. Skinfolds were measured with an Eiken-model skinfold caliper. Age (mean 33.1, range 19-60 yrs.), weight (mean 65.3, range 46.6-107.7 kg), height (mean 168.8, range 152.3-185.4 cm), and body density (mean 1.05874, range 1.00860-1.09020 g/ml) were also recorded. Percent body fat was calculated using the formula by Brozek et al. and ranged from 6.1% to 38.9%. Multiple correlation coefficients (MR) and standard error (SE) of 10 regression equations (A-J) for predicting body density in men were obtained. The best-fitting and the most convenient prediction equation for body density was equation-E.: body density = 1.09556-0.00062 x sum of three skinfolds (mm)-0.00028 x age (MR = 0.815 and SE = 0.0087 g/ml). The equation was cross-validated on a different sample of 45 men. The correlation coefficient between predicted and hydrostatically determined body density was 0.781 (p < 0.001). Equation-E (Tahara's equation) appears to be useful in body density analysis particularly when the subjects are Japanese men, aged 18-50 yrs, with percent body fat 10 to 30%.

Antibacterial properties of lansoprazole alone and in combination with antimicrobial agents against Helicobacter pylori

The activities of various types of antiulcer agents against Helicobacter pylori strains were determined by an agar dilution method. Among the compounds tested, benzimidazole proton pump inhibitors were found to have significant activity against this organism. The activity of lansoprazole was fourfold more potent than that of omeprazole and bismuth subsalicylate, with MICs ranging from 1.56 to 25 micrograms/ml. Exposure of Helicobacter pylori to lansoprazole led to an extensive loss of viability as well as suppression of virulence factors such as motility, adhesiveness to epithelial cells and urease activity. The combination of lansoprazole with antimicrobial agents such as penicillins, cephalosporins, macrolides, tetracyclines, aminoglycosides, quinolones, metronidazole and bismuth subsalicylate generally had an additive effect on inhibition of Helicobacter pylori growth.