Abstract
Cluster of differentiation 44 (Cd44), a hyaluronan receptor, and the secreted hyaluronan-binding protein Inter-α-trypsin Inhibitor Heavy chain 3 (Itih3) play an important role in cancer and oxidative stress. Smoking of tobacco reduces Itih3 in the plasma and activates hyaluronan signaling through Cd44, but the impact of Cd44 on Itih3 expression is unknown. Here, we studied changes induced by the tobacco component nicotine on the glutathione (GSH) antioxidant system and Itih3 gene expression in Cd44 knockout mice. Cd44 deficiency decreased baseline total GSH and oxidized glutathione (GSSG) levels in the liver compared to wildtype mice. However, contrary to wildtype mice, chronic oral nicotine administration (200 μg/ml) failed to further reduce total GSH and GSSG in Cd44 mice. Sex differences with lowered glutathione levels in females was also detectable only in wildtype but not Cd44 knockout mice. Itih3 mRNA levels in the liver and hypothalamus were not affected by nicotine, Cd44 genotype or sex. Nonetheless, the correlation between Itih3 and total GSH levels in the liver (r = 0.42, p < 0.05) suggested a role of Itih3 in glutathione metabolism in WT mice. Again this effect was diminished in Cd44 knockout mice. The disappearance of nicotine effects, sex differences and correlations between Itih3 and total GSH in Cd44 knockout mice compared to wildtype animals suggests an interaction between nicotine, Cd44 and/or sex-dependent signaling in the regulation of glutathione metabolism.