Regulation of Renal Transporters by Pro-inflammatory Cytokines in Human Proximal Tubular Epithelial Cells: Identification of the Perpetrator and Mechanisms.

Introduction: Infection and inflammation elevate circulating pro-inflammatory cytokines that can affect renal drug clearance. Accordingly, we sought to (i) quantify the extent of modulation of renal drug-metabolizing enzymes and transporters (DMETs) by cytokines and (ii) identify the mechanism(s) underlying these effects. Methods: Fresh primary human proximal tubular epithelial cells (PTECs) were cultured on extracellular matrix-coated Transwells. PTECs were exposed every 24 h, for 48 h, to IL-6, IL-1β, TNF-α, IFN-γ, IL-4, or IL-10 (0.1 or 1 ng/mL), individually or as a cocktail. mRNA expression of 25 renal DMETs was quantified by RT-qPCR. Individual activity of OAT1-4, OCT2, and OCTN1 was measured. To determine mechanisms of these effects, selective MAPK/NF-κB inhibitors (ERK [PD98059], p38 Results: IL-1β was the predominant modulator, downregulating mRNA expression of OAT1-3, OCT2, OAT4, MATE2-K, MRP2, and OATP4C1, and upregulating mRNA expression of OCTN1 and MRP3. TNF-α downregulated OAT1-3 mRNA expression to an extent similar to IL-1β, but did not affect other transporters. Activity changes for the major uptake transporters mirrored mRNA directionality. MAPK/NF-κB blockade by the inhibitor cocktail reduced IL-6 secretion while completely reversing the IL-1β-driven downregulation of OAT1-3 mRNA. JNK inhibition alone restored OAT1/3 mRNA. Inhibition of p38 Conclusions: IL-1β is the principal driver of cytokine-mediated regulation of human renal transporters in PTECs via JNK/p38