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Funken, Dominik; Ishikawa-Ankerhold, Hellen; Uhl, Bernd; Lerchenberger, Maximilian; Rentsch, Markus; Mayr, Doris; Massberg, Steffen; Werner, Jens; Khandoga, Andrej (2017): In situ targeting of dendritic cells sets tolerogenic environment and ameliorates CD4(+) T-cell response in the postischemic liver. In: Faseb Journal, Vol. 31, No. 11: pp. 4796-4808
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Abstract

CD4(+) T cells recruited to the liver play a key role in the pathogenesis of ischemia/reperfusion (I/R) injury. The mechanism of their activation during alloantigen-independent I/R is not completely understood. We hypothesized that liver-resident dendritic cells (DCs) interact with CD4(+) T cells in the postischemic liver and that modulation of DCs or T-cell-DC interactions attenuates liver inflammation. In mice, warm hepatic I/R (90/120-240 min) was induced. Tolerogenic DCs were generated in situ by pretreatment of animals with the vitamin D analog paricalcitol. A mAb-CD44 was used for blockade of CD4(+) T-cell-DC interactions. As shown by 2-photon in vivo microscopy as well as confocal microscopy, CD4(+) T cells were closely colocalized with DCs in the postischemic liver. Pretreatment with paricalcitol attenuated I/R-induced maturation of DCs (flow cytometry), CD4(+) T-cell recruitment into the liver (intravital microscopy), and hepatocellular/microvascular damage (intravital microscopy, alanine aminotransferase/aspartate aminotransferase, histology). However, interruption of T-cell-DC interaction increased proinflammatory DC maturation and even enhanced tissue damage. Simultaneous treatment with an anti-CD44mAb completely abolished the beneficial effect of paricalcitol on T-cell migration and tissue injury. Our study demonstrates for the first time that hepatic DCs interact with CD4(+) T cells in the postischemic liver in vivo;modulation of DCs and/or generation of tolerogenic DCs attenuates intrahepatic CD4(+) T-cell recruitment and reduces I/R injury;and interruption of CD44-dependent CD4(+) T-cell-DC interactions enhances tissue injury by preventing the modulatory effect of hepatic DCs on T cells, especially type 1 T helper effector cells. Thus, hepatic DCs are strongly involved in the promotion of CD4(+) T-cell-dependent postischemic liver inflammation.