Influence of the pro-inflammatory cytokines on P-glycoprotein expression and functionality.

Purpose: P-glycoprotein (P-gp) is involved in the transport of many drugs at different barriers with consequence in terms of drug distribution and elimination. The expression and activity of P-gp can be modulated by different factors and pathologies. The present article reviews the knowledge regarding the effect of pro-inflammatory cytokines (TNF alpha, IL-1 beta, IL-6, IL-2, IFN gamma) on the expression and the functionality of P-gp at three major sites of drug absorption and disposition: the liver, the blood-brain barrier, and the intestine. Methods: The various methods used to study the effect of proinflammatory cytokines include in vivo models (i.e. animals infected with Staphylococcus sp, animals injected with bacterial lipopolysaccharide or directly with cytokines,.) and in vitro models (i.e. primary rat hepatocytes, human brain endothelial cells,.). Results: The data on P-gp expression and/or function may differ according to the compound used to induce inflammation. However, there is a general trend towards a decrease in both the expression of P-gp ( mRNA and protein) and its functionality. Transcription factors and nuclear receptors are probably involved in this regulation. Conclusion: Cytokines may interfere with P-gp. Hence, in pathological conditions ( inflammation, infection,.), the expression and functionality of P-glycoprotein may be modulated with consequences for drug disposition and, consequently treatment efficacy.