TAK-242, a novel Toll-like receptor 4 signal transduction inhibitor, protects mice in Escherichia coli-induced and lipoteichoic acid-induced lethality models

Objectives

Toll-like receptor 4 (TLR4) is a pattern recognition receptor of various host and bacterial ligands. TLR4 ligands such as lipopolysaccharide activate immune cells and induce production of many cytokines, which are involved in the onset of sepsis. TAK-242 is a novel small molecule that selectively inhibits TLR4-induced production of multiple cytokines by monocytes and macrophages. The in-vivo potential of TAK-242 was examined in models of Escherichia coli (Gram-negative)-induced and lipoteichoic acid (LTA) (Gram-positive)-induced lethality in mice.

Methods

E. coli was inoculated intraperitoneally in Bacillus calmette guerin-primed mice. One hour after bacterial inoculation, TAK-242 was intravenously administered with antibiotics. LTA-induced lethality was induced by the intraperitoneal administration of LTA and D-galactosamine. Cytokine levels in sera were determined by specific ELISAs and survival through 7 days was recorded.

Results

TAK-242 coadministered with ceftazidime (CAZ) dose-dependently protected mice from E. coli-induced lethality; CAZ alone was ineffectual. Statistically significant protection was observed at 0.3 mg/kg or more of TAK-242 (n = 10, P ≤ 0.05) and 3 mg/kg prevented lethality in all mice. The increases in serum levels of not only proinflammatory cytokines such as TNF-α and IL-1β, but also an anti-inflammatory cytokine, IL-10, were significantly and dose-dependently suppressed by TAK-242. Increase cytokine levels were quickly and markedly suppressed by the treatment with TAK-242 even when cytokine levels had already increased significantly. The doses that prevented lethality and inhibited cytokine production were similar, suggesting that TAK-242 rescued mice by suppressing excessive cytokine production and inflammation. TAK-242 did not increase bacterial counts in blood, although it suppressed cytokine production. TAK-242 showed similar protective effects when the antibiotics imipenem or gentamicin were used in place of CAZ, suggesting TAK-242 would work in combination with various types of antibiotics. In addition, TAK-242 dose-dependently suppressed the LTA-induced increase in serum IL-6 levels in mice and rescued mice from death. Statistically significant protection was observed at 0.3 mg/kg or more of TAK-242 (n = 10, P ≤ 0.05) and 3 mg/kg rescued all mice. The efficacy in the LTA model was, therefore, comparable with that in the E. coli model.

Conclusion

TAK-242 showed marked and similar protective effects in Gram-negative and Gram-positive murine models of sepsis. These data suggest that TAK-242 may be a novel therapeutic treatment for sepsis. A pivotal clinical trial of TAK-242 to test this hypothesis is ongoing.