Differential expression of influx and efflux transport proteins in human antigen presenting cells

Abstract

Human macrophages (MF) express cytochrome P450 enzymes verifying their capacity to metabolize a variety of endogenous and exogenous substances. Here we analysed the mRNA and protein expression of transport proteins involved in the uptake or export of drugs, hormones and arachidonic acid metabolites in dendritic cells (DC) and MF compared to their precursors -blood monocytes -using cDNA microarray, RT-PCR, Western-blot and immunostaining techniques. The transport proteins studied included members of the solute carrier organic anion transporter family (SLCO) and the multidrug resistance associated proteins (MRP) 1-6 belonging to the ATP-binding cassette subfamily C (ABCC). We found that only mRNA for SLCO-2B1, -3A1, and -4A1 were present in monocytes, MF and DC. Most interestingly the expression of SLCO-2B1 was markedly enhanced in MF as compared to monocytes and DC. The presence of mRNA for ABCC1, 3, 4, 5 and 6 in all three cell types was demonstrated. On protein level ABCC1 ⁄ MRP1 which has been identified as leukotriene C 4 transporter was found to be the most abundant transporter in MF and DC. Blocking the ABCC1 ⁄ MRP1 activity with the specific inhibitor MK571 resulted in a phenotypic change in DC but not in MF. Our data show that human blood monocytes and monocyte derived MF as well as DC express a specific profile of transporters involved in uptake and export of exogenous molecules like allergens or drugs, but also of endogenous substances in particular of inflammatory lipid mediators like leukotrienes and prostaglandins.

P-Glycoprotein (ABCB1) expression in human skin is mainly restricted to dermal components

“…The critical importance of ABC transporters in normal physiology is also demonstrated by the fact that mutations in several of these genes result in heritable diseases (4,5). One of these conditions is pseudoxanthoma elasticum (PXE), a multi-system heritable disorder characterized by ectopic mineralization of soft connective tissues, with clinical consequences in the skin, the eyes, and the cardiovascular system (6,7). PXE is caused by mutations in the ABCC6 gene that is expressed primarily in the liver, to the lesser extent in the kidneys, and at relatively low levels, if at all, in tissues with clinical manifestations (6)(7)(8)(9)(10).…”

“…One of these conditions is pseudoxanthoma elasticum (PXE), a multi-system heritable disorder characterized by ectopic mineralization of soft connective tissues, with clinical consequences in the skin, the eyes, and the cardiovascular system (6,7). PXE is caused by mutations in the ABCC6 gene that is expressed primarily in the liver, to the lesser extent in the kidneys, and at relatively low levels, if at all, in tissues with clinical manifestations (6)(7)(8)(9)(10). The role of ABCC6 as the gene underlying PXE is also attested to by the development of Abcc6 ) ⁄ ) mice, which recapitulate the genetic, histopathologic and ultrastructural features of human PXE (11,12).…”

Identification and Characterization of a Novel Class of c-Jun N-terminal Kinase Inhibitors

“…Thus, their different chemical structures may result in different physical properties that affect their activity in various cell types, which have different biological properties, such as membrane permeability, expression of P-glycoproteins, etc. Indeed, macrophage differentiation is known to affect the level of expression of protein transporters involved in movement of exogenous molecules (Skazik et al, 2008;Moreau et al, 2011). Hence, different compounds may be active in one cell line and less active or even inactive in another.…”

Effects of AF3442 [N-(9-ethyl-9H-carbazol-3-yl)-2-(trifluoromethyl)benzamide], a novel inhibitor of human microsomal prostaglandin E synthase-1, on prostanoid biosynthesis in human monocytes in vitro

“…Excess PGH 2 may be immediately released outside the cell after intracellular biosynthesis -probably through the action of MRP4/ABCC4 (multidrug resistance protein 4 adenosine triphosphate-binding cassette, subfamily C, member 4) [34] or simple diffusion -and then it may be reuptaken, probably via the prostaglandin transporter [35,36]. Thus, shunting of PGH 2 to other prostanoids may be dependent on the expression of transport proteins in different cell types.…”