LPS-induced TNF-α factor (LITAF) mediates cytokine expression in response to endotoxin challenge. Previously, we reported that macrophage-specific LITAF-deficient (macLITAF −/− ) mice exposed to LPS have a delayed onset in the serum levels of proinflammatory cytokines and prolonged persistence of anti-inflammatory cytokines, but only partial protection from endotoxic shock. We postulated that greater protection might be achieved if LITAF were deleted from all LITAF-producing cells, including macrophages. Using a Cre-loxP system, we engineered a tamoxifen-induced recombination mouse [tamLITAF(i)] that resulted in whole-body LITAF deficiency. Our findings demonstrate that (i) tamLITAF(i) −/− mice are more resistant to systemic Escherichia coli LPS-induced lethality than our previous macLITAF −/− mice, providing evidence that LITAF-producing cells other than LysMCre-positive cells play an important role in mediating endotoxic shock; (ii) tamLITAF(i) −/− mice show a similar pattern of cytokine expression with decreased proinflammatory and prolonged anti-inflammatory mediators compared with WT mice; and (iii) tamLITAF(i) −/− mice, compared with WT mice, display a significant reduction in bone resorption and inflammation associated with a local chronic inflammatory disease-namely, collagen antibody-induced arthritis. Our findings offer a unique model to study the role of LITAF in systemic and chronic local inflammatory processes, and pave the way for anti-LITAF therapeutic approaches for the treatment of TNF-mediated inflammatory diseases.septic shock | multiplex

There is a substantial unmet need for new classes of drugs that block TNF-α-mediated inflammation, and particularly for small molecule agents that can be taken orally. We have screened a library of natural products against an assay measuring TNF-α secretion in lipopolysaccharide (LPS)-stimulated THP-1 cells, seeking compounds capable of interfering with the TNF-α inducing transcription factor Lipopolysaccharide Induced TNF Alpha Factor (LITAF). Among the active compounds were several produced by the kava plant (Piper mysticum), extracts of which have previously been linked to a range of therapeutic effects. When tested in vivo, a representative of these compounds, kavain, was found to render mice immune to lethal doses of LPS. Kavain displays promising pharmaceutical properties, including good solubility and high cell permeability, but pharmacokinetic experiments in mice showed relatively rapid clearance. A small set of kavain analogs was synthesized, resulting in compounds of similar or greater potency in vitro compared to kavain. Interestingly, a ring-opened analog of kavain inhibited TNF-α secretion in the cell based assay and suppressed LITAF expression in the same cells, whereas the other compounds inhibited TNF-α secretion without affecting LITAF levels, indicating a potential divergence in mechanism of action.

Abnormal and prolonged inflammatory reaction is seen in a wide variety of disorders, and high level of Tumor Necrosis Factor alpha (TNF-α) has been linked to these disorders. Therefore, modulation of TNF-α expression is important in the regulation of inflammatory disorders. In our previous study, we have shown that a transcription factor LPS-induced TNF factor (LITAF) significantly induces TNF-α production. Furthermore, we found that p53 and its synthetic peptide 162-motif specifically downregulate LITAF/TNF-α gene expression in human cells in vitro. Thus, in the present study, the role of p53 in regulating TNF-α-mediated inflammation was investigated. Our data showed that a synthetic peptide, named 162-motif, corresponding to this region functions independently from p53 to cause a significant suppression of TNF-α gene expression in mouse primary macrophages. The 162-motif, when delivered into cells and organs, reduces serum TNF-α level in mice and prevents TNF-α-induced lung lesions and endotoxic shock. Our findings highlight the regulation of LITAF/TNF-α by p53 and its short peptide 162-motif. These in vitro and in vivo observations serve to pave the way for pharmacotherapeutic approaches in the treatment of inflammatory diseases.