Migration of leukocytes across an endothelium-epithelium bilayer as a model of renal interstitial inflammation. Am J Physiol Cell Physiol 293: C486-C492, 2007. First published April 11, 2007 doi:10.1152/ajpcell.00419.2006.-Interstitial inflammation has emerged as a key event in the development of acute renal failure. To gain better insight into the nature of these inflammatory processes, the interplay between tubular epithelial cells, endothelial cells, and neutrophils (PMN) was investigated. A coculture transmigration model was developed, composed of human dermal microvascular endothelial (HDMEC) and human renal proximal tubular cells (HK-2) cultured on opposite sides of Transwell growth supports. Correct formation of an endoepithelial bilayer was verified by light and electron microscopy. The model was used to study the effects of endotoxin (LPS), tumor necrosis factor (TNF)-␣, and ␣-melanocyte-stimulating hormone (␣-MSH) by measuring PMN migration and cytokine release. To distinguish between individual roles of microvascular endothelial and epithelial cells in transmigration processes, migration of PMN was investigated separately in HK-2 and HDMEC monolayers. Sequential migration of PMN through endothelium and epithelium could be observed and was significantly increased after proinflammatory stimulation with either TNF-␣ or LPS (3.5 Ϯ 0.58 and 2.76 Ϯ 0.64-fold vs. control, respectively). Coincubation with ␣-MSH inhibited the transmigration of PMN through the bilayer after proinflammatory stimulation with LPS but not after TNF-␣. The bilayers produced significant amounts of IL-8 and IL-6 mostly released from the epithelial cells. Furthermore, ␣-MSH decreased LPS-induced IL-6 secretion by 30% but had no significant effect on IL-8 secretion. We established a transmigration model showing sequential migration of PMN across microvascular endothelial and renal tubular epithelial cells stimulated by TNF-␣ and LPS. Anti-inflammatory effects of ␣-MSH in this bilayer model are demonstrated by inhibition on PMN transmigration and IL-6 secretion.coculture; polymorphonuclear neutrophil migration; HK-2; interleukin-8; interleukin-6; ␣-melanocyte-stimulating hormone
IntroductionLevosimendan is an extensively investigated inodilator showing also cardioprotective and antiinflammatory effects. The aim of our study was to explore the influence of levosimendan on polymorphonuclear leucocytes (PMN), a main source of reactive oxygen species, in vitro and in patients with acute heart failure or septic myocardial depression.MethodsPMN isolated from healthy volunteers were incubated with levosimendan in vitro. After stimulation with N-formyl-Met-Leu-Phe (fMLP) or phorbol 12-myristate 13-acetate (PMA) respiratory burst was quantified using a fluorescent dye. Apoptosis and expression of cell adhesion molecules of PMN were measured by flow cytometry. For determination of in vivo effects patients with acute heart failure (n = 16) or septic cardiac failure (n = 9) receiving levosimendan treatment were enrolled consecutively. PMN were isolated to measure respiratory burst activity before treatment as well as one and two hours after initiation of levosimendan administration. Furthermore inflammatory, hemodynamic and renal function parameters were obtained.ResultsIn vitro, levosimendan suppressed respiratory burst activity in fMLP or PMA stimulated PMN in a dose dependent manner by 30 ± 11% (P < 0.001) at 100 ng/mL and by 27 ± 17% (P < 0.001) at 1000 ng/mL respectively. Markers of apoptosis and PMN cell adhesion molecule expression remained unaffected by levosimendan treatment.In vivo, levosimendan treatment for two hours resulted in a significant reduction of PMA stimulated oxidative burst by 45% (P < 0.01) and fMLP stimulated oxidative burst by 49% (P < 0.05) in patients with acute heart failure. In patients suffering from septic shock levosimendan treatment decreased oxidative burst activity in unstimulated, fMLP and PMA stimulated PMN by 48% (P < 0.05), 46% (P < 0.01) and 43% (P < 0.01) respectively.ConclusionsLevosimendan appears to exert distinct immunomodulatory effects by decreasing oxidative burst activity of PMN. This property might contribute to the previously described cardioprotective effects of the drug.
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