CHEMOKINE RECEPTORS

Role of human LZIP in differential activation of the NF-kappaB pathway that is induced by CCR1-dependent chemokines

Human leucine zipper protein (LZIP) associates with CC chemokine receptor 1 (CCR1) and this protein-protein interaction should play an important role in leukocyte cell mobility. LZIP is known to regulate leukotactin-1 (Lkn-1)-dependent cell migration without affecting the chemotactic activities of other CC chemokines that bind to CCR1. Since Lkn-1 is engaged in the transcriptional activation of nuclear factor kappaB (NF-kappaB) and subsequent activation of the chemoattractant ability of leukocytes, we investigated the regulatory role of LZIP in the NF-kappaB pathway that is induced by CCR1-dependent chemokines. LZIP increased NF-kappaB-dependent luciferase activity in response to Lkn-1 in HOS/CCR1 cells and THP-1 cells. However, the NF-kappaB-dependent luciferase activities induced by other CCR1-dependent chemokines were not affected by LZIP overexpression. LZIP also increased Lkn-1-induced chemotactic activity through activation of the NF-kappaB pathway, whereas LZIP did not affect either the transactivation of NF-kappaB or the chemotactic activities induced by other CCR1-dependent chemokines. Western blot analysis showed that LZIP increased the degradation of IkappaBalpha induced by Lkn-1 but not by other CCR1-dependent chemokines. Results from electrophoretic mobility shift assay (EMSA) showed that LZIP enhanced the Lkn-1-induced DNA-binding activity of NF-kappaB. These data indicate that LZIP functions as a positive regulator in the NF-kappaB activation pathway that is triggered by Lkn-1 without affecting the transcriptional activation of NF-kappaB induced by other CCR1-dependent chemokines.

Simvastatin down regulates mRNA expression of RANTES and CCR5 in posttransplant renal recipients with hyperlipidemia

Chemokines and hyperlipidemia are involved in the mechanism of chronic allograft nephropathy (CAN). In this study, the mRNA expression of RANTES and its receptor CCR5 on peripheral blood mononuclear cells were measured in renal transplant recipients with hyperlipidemia, and the effect of simvastatin treatment observed to investigate the mechanism and prevention of CAN. Sixty recipients selected from 167 renal transplant recipients were divided into two groups: group A without hyperlipidemia (n = 30) and group B with hyperlipidemia (n = 30). The control group consisted of 30 healthy volunteers. The recipients in group B were treated with simvastatin for 3 months. We estimated serum lipid levels and mRNA expressions of RANTES and CCR5. The mRNA expressions of RANTES and CCR5 were significantly higher in renal transplant recipients compared with controls. The expressions were much higher in group B than in group A patients. In group B patients, serum lipid levels decreased dramatically after simvastatin treatment. Meanwhile, the mRNA expressions of RANTES and CCR5 were reduced significantly after 1.5 months of simvastatin treatment to a level significantly lower than that in group A after 3 months of treatment. The increased expressions of RANTES and CCR5 mRNAs in renal transplant recipients with hyperlipidemia might be involved in CAN due to hyperlipidemia. Simvastatin seemed to reduce the chemokine transcripts in renal recipients with hyperlipidemia.