Tumor necrosis factor alpha increases P‐glycoprotein expression in a BME‐UV in vitro model of mammary epithelial cells

Abstract

P-glycoprotein is an efflux pump belonging to the ATP-binding cassette super-family that influences the bioavailability and disposition of many drugs. Mammary epithelial cells express various drug transporters including P-glycoprotein, albeit at low level during lactation. During inflammatory reactions, which can be associated with changes in epithelial barrier functions, pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) are elevated in milk and serum. In this study, the role of TNF-α in the regulation of P-glycoprotein was determined in cultured BME-UV cells, an immortalized bovine mammary epithelial cell line. The protein production of P-glycoprotein and mRNA expression of bABCB1, the gene encoding P-glycoprotein, were increased after 24 hours of TNF-α exposure. The highest observed effects for TNF-α on the regulation of P-glycoprotein was after 72 hours of exposure. Protein and mRNA expression also significantly increased after 120 hours of TNF-α exposure, but it was lower than the level that observed in the cells exposed to TNF-α for 72 hours. The apical to basolateral flux of digoxin, a P-glycoprotein substrate, was decreased in the TNF-α-exposed epithelium. This effect was reversed when verapamil or ketoconazole, compounds known to interact with P-glycoprotein, were added together with digoxin into the donor compartment. Probenecid, a compound known to interact with organic anion transporters, but not P-glycoprotein, did not increase the flux of digoxin. This model has important implications for understanding the barrier function of the mammary epithelium and provides insight into the role of P-glycoprotein in the accumulation and/or removal of xenobiotics from milk and/or plasma.

The Androgen Metabolite, 5α-androstane-3β,17β-diol, Decreases Cytokine-Induced Cyclooxygenase-2, Vascular Cell Adhesion Molecule-1 Expression, and P-Glycoprotein Expression in Male Human Brain Microvascular Endothelial Cells

“…Our current data show that the cytokine IL-1␤ increases protein expression of Pgp in a fashion similar to that reported by others, in epithelial cells (18), rat astrocytes (23), a human brain endothelial cell line (6), rat brain endothelial cells (19), and isolated rat brain capillaries (20,21). This is consistent with the effects elicited by other cytokines such as TNF␣, which has been shown to increase Pgp protein and mRNA expression in a human brain endothelial cell line (6) and to increase Pgp protein expression and activity in rat brain capillaries (21).…”

“…Studies have shown that factors that promote inflammation increase Pgp expression/activity in both human and rodent cells/ tissue (6,(18)(19)(20)(21)(22)(23). For example, the cytokine, TNF␣, has been shown to increase Pgp protein and mRNA expression in human and rat brain endothelial cell lines (6,22).…”

Prenatal Endotoxemia and Placental Drug Transport in The Mouse: Placental Size-Specific Effects

“…In this context, multidrug resistance transporters such as P-glycoprotein (P-gp; encoded by Abcb1a/b genes in the mouse) and breast cancer resistance protein (BCRP; encoded by Abcg2 gene), are functionally modulated by pro-inflammatory agents in different tissues/cell types [5]–[10]. P-gp and BCRP are extensively expressed in different tissue barriers such as the placenta, blood-brain barrier, mammary gland, colon and small intestine [11].…”

Challenges associated with the demonstration of bioequivalence of intramammary products in ruminants

“…Most recently, the effect of acute inflammation on the mammary epithelial integrity has been assessed. It was shown that TNF α may decrease the flux of drugs across the mammary epithelial monolayer by upregulating the expression of P‐glycoprotein (P‐gp) during mastitis soon after the cells are exposed to this inflammatory cytokine (Al‐bataineh et al. , 2010).…”