tetrathiomolybdate and Carbon-Tetrachloride-Poisoning

The background for this study is that we have observed some improvement in cirrhosis in Wilson's disease patients treated with the anticopper medicine, zinc, and another anticopper drug, tetrathiomolybdate, has completely prevented hepatic fibrosis in the carbon tetrachloride mouse model. We hypothesize that in existing cirrhosis, there may be a fine balance between fibrosis formation and fibrosis dissolution, which may be pushed in the direction of dissolution by anticopper drugs. Thus, in this study, we produced hepatic fibrosis in mice by treatment with carbon tetrachloride, then gave half the fibrotic mice tetrathiomolybdate for 3 months, while the other half of the fibrotic mice received nothing for 3 months and served as controls. Tetrathiomolybdate caused a dramatic and significant reduction in fibrosis as measured by hydroxyproline (the major amino acid constituent of collagen) levels, almost back to baseline levels, compared to controls, who had only a slight and nonsignificant reduction. It is clear from this animal study that dissolution of preexisting fibrosis can be strongly catalyzed by lowering copper levels with tetrathiomolybdate. It now becomes important to evaluate whether this approach will work in the human epidemic of cirrhotic disease resulting from diseases such as alcoholism, nonalcoholic steatohepatitis, and hepatitis C.

Topics: Animals; Carbon Tetrachloride; Carbon Tetrachloride Poisoning; Copper; Female; Hepatolenticular Degeneration; Humans; Liver Cirrhosis, Experimental; Mice; Mice, Inbred BALB C; Molybdenum; Time Factors

Tetrathiomolybdate, an anticopper drug, has been shown to protect mice against pulmonary fibrosis from bleomycin. Our hypothesis is that it does so by inhibiting fibrosis-inducing cytokines. Indeed, we have good evidence, not yet published, that tetrathiomolybdate inhibits pulmonary levels of transforming growth factor-beta and tumor necrosis factor-alpha expression in these bleomycin experiments. Herein, we evaluate tetrathiomolybdate's effectiveness in mitigating hepatitis and fibrosis in mice from the hepatotoxins, concanavalin A and carbon tetrachloride, and its inhibition of cytokines as a possible mechanism. In short-term experiments, concanavalin A elevated serum amino leucine transferase levels several fold, and tetrathiomolybdate completely prevented this increase. In additional experiments, tetrathiomolybdate therapy reversed the elevated serum transaminase levels despite continued concanavalin A injections, with nearly significant serum interleukin-1beta inhibition. Concanavalin A given for 12 weeks produced mild fibrosis, whereas concomitant tetrathiomolybdate treatment resulted in normal histology. Carbon tetrachloride given for 12 weeks resulted in very high serum amino leucine transferase levels, high serum transforming growth factor-beta levels, cirrhosis as seen histologically, and increase in liver hydroxyproline, a measure of fibrosis. Concomitant tetrathiomolybdate partially and significantly protected against increases in amino leucine transferase and transforming growth factor-beta, fully protected against the increase in hydroxyproline, and resulted in normal histology. In conclusion, tetrathiomolybdate protects against the hepatitis and fibrosis produced by these hepatotoxins, probably by inhibiting the excessive increase in inflammatory and fibrotic cytokines.

Topics: Alanine Transaminase; Animals; Carbon Tetrachloride Poisoning; Chelating Agents; Concanavalin A; Copper; Cytokines; Hydroxyproline; Liver; Mice; Mice, Inbred BALB C; Mice, Inbred CBA; Molybdenum