ABSTRACT
Inflammatory process is involved in the pathogenesis of diabetic nephropathy. In this article, we show that cholecystokinin (CCK) is expressed in the kidney and exerts renoprotective effects through its anti-inflammatory actions. DNA microarray showed that CCK was upregulated in the kidney of diabetic wild-type (WT) mice but not in diabetic intracellular adhesion molecule-1 knockout mice. We induced diabetes in CCK-1 receptor (CCK-1R) and CCK-2R double-knockout (CCK-1R(-/-),-2R(-/-)) mice, and furthermore, we performed a bone marrow transplantation study using CCK-1R(-/-) mice to determine the role of CCK-1R on macrophages in the diabetic kidney. Diabetic CCK-1R(-/-),-2R(-/-) mice revealed enhanced albuminuria and inflammation in the kidney compared with diabetic WT mice. In addition, diabetic WT mice with CCK-1R(-/-) bone marrow-derived cells developed more albuminuria than diabetic CCK-1R(-/-) mice with WT bone marrow-derived cells. Administration of sulfated cholecystokinin octapeptide (CCK-8S) ameliorated albuminuria, podocyte loss, expression of proinflammatory genes, and infiltration of macrophages in the kidneys of diabetic rats. Furthermore, CCK-8S inhibited both expression of tumor necrosis factor-α and chemotaxis in cultured THP-1 cells. These results suggest that CCK suppresses the activation of macrophage and expression of proinflammatory genes in diabetic kidney. Our findings may provide a novel strategy of therapy for the early stage of diabetic nephropathy.
Subject(s)
Cholecystokinin/metabolism , Diabetes Mellitus/metabolism , Inflammation/metabolism , Kidney/metabolism , Macrophages/physiology , Animals , Chemokines, CC , Chemotaxis/drug effects , Cholecystokinin/genetics , Gene Expression Profiling , Gene Expression Regulation/physiology , Intercellular Adhesion Molecule-1/genetics , Intercellular Adhesion Molecule-1/metabolism , Male , Mice , Mice, Knockout , NF-kappa B/genetics , NF-kappa B/metabolism , Receptor, Cholecystokinin B/genetics , Receptor, Cholecystokinin B/metabolism , Receptors, Cholecystokinin/genetics , Receptors, Cholecystokinin/metabolism , Sincalide/analogs & derivatives , Sincalide/pharmacology , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/metabolismABSTRACT
Glomerular hyperfiltration is a common pathway leading to glomerulosclerosis in various kinds of kidney diseases. The 5/6 renal ablation is an established experimental animal model for glomerular hyperfiltration. On the other hand, low-grade inflammation is also a common mechanism for the progression of kidney diseases including diabetic nephropathy and atherosclerosis. Here we analyzed the gene expression profile in the remnant kidney tissues of 5/6 nephrectomized mice using a DNA microarray system and compared it with that of sham-operated control mice. The 5/6 nephrectomized mice showed glomerular hypertrophy and an increase in the extracellular matrix in the glomeruli. DNA microarray analysis indicated the up-regulated expression of various kinds of genes related to the inflammatory process in remnant kidneys. We confirmed the up-regulated expression of platelet factor-4, and monocyte chemoattractant protein-1, 2, and 5 in remnant kidneys by RT-PCR. The current results suggest that the inflammatory process is involved in the progression of glomerulosclerosis and is a common pathway of the pathogenesis of kidney disease.
Subject(s)
Glomerular Filtration Rate , Kidney/pathology , Macrophages/physiology , Animals , Chemokines/genetics , Gene Expression Profiling , Male , Mice , Mice, Inbred C57BL , Oligonucleotide Array Sequence Analysis , SclerosisABSTRACT
OBJECTIVE: An inflammatory process is involved in the mechanism of obesity-related insulin resistance. Recent studies indicate that monocyte chemoattractant protein-1 (MCP-1) is a major chemokine that promotes monocyte infiltration into adipose tissues; however, the adhesion pathway in adipose tissues remains unclear. We aimed to clarify the adhesion molecules that mediate monocyte infiltration into adipose tissue. RESEARCH DESIGN AND METHODS: We used a DNA microarray to compare the gene expression profiles in epididymal white adipose tissues (eWAT) between db/db mice and C57/BL6 mice each fed a high-fat diet (HFD) or a low-fat diet (LFD). We investigated the change of insulin resistance and inflammation in eWAT in P-selectin glycoprotein ligand-1 (PSGL-1) homozygous knockout (PSGL-1â»(/)â») mice compared with wild-type (WT) mice fed HFD. RESULTS: DNA microarray analysis revealed that PSGL-1, a major ligand for selectins, is upregulated in eWAT from both db/db mice and WT mice fed HFD. Quantitative real-time RT-PCR and immunohistochemistry showed that PSGL-1 is expressed on both endothelial cells and macrophages in eWAT of obese mice. PSGL-1â»(/)â» mice fed HFD showed a remarkable reduction of macrophage accumulation and expression of proinflammatory genes, including MCP-1 in eWAT. Moreover, adipocyte hypertrophy, insulin resistance, lipid metabolism, and hepatic fatty change were improved in PSGL-1â»(/) â»mice compared with WT mice fed HFD. CONCLUSIONS: These results indicate that PSGL-1 is a crucial adhesion molecule for the recruitment of monocytes into adipose tissues in obese mice, making it a candidate for a novel therapeutic target for the prevention of obesity-related insulin resistance.
Subject(s)
Insulin Resistance/physiology , Membrane Glycoproteins/deficiency , Obesity/prevention & control , Adipocytes/physiology , Animals , DNA Primers , Diet, Fat-Restricted , E-Selectin/genetics , Fatty Liver/prevention & control , Flow Cytometry , Gene Expression Profiling , Glucose Tolerance Test , Humans , Inflammation/genetics , Inflammation/physiopathology , Insulin/pharmacology , Insulin Resistance/genetics , Membrane Glycoproteins/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Obesity/genetics , Oligonucleotide Array Sequence Analysis , P-Selectin/genetics , Phosphorylation , Reverse Transcriptase Polymerase Chain Reaction , Up-RegulationABSTRACT
Recently, sphingosine 1-phosphate (S1P) has been highlighted as an endothelial barrier-stabilizing mediator. FTY720 is a S1P analog originally developed as a novel immunosuppressant. The phosphorylated form of FTY720 binds to S1P receptors to exert S1P-like biological effects, suggesting endothelial barrier promotion by FTY720. To elucidate whether FTY720 induces signaling events related to endothelial barrier enhancement under hyperglycemic conditions, human microvascular endothelial cells (HMVECs) preincubated with hyperglycemic (30 mM) medium were treated with 100 nM FTY720 for 3 h. Immunofluorescent microscopy and coprecipitation study revealed FTY720-induced focal adhesion kinase (FAK)-associated adherens junction (AJ) assembly at cell-cell contacts coincident with formation of a prominent cortical actin ring. FTY720 also induced transmonolayer electrical resistance (TER) augmentation in HMVEC monolayers in both normoglycemic and hyperglycemic conditions, implying endothelial barrier enhancement. Similar to S1P, site-specific FAK tyrosine phosphorylation analysis revealed FTY720-induced FAK [Y576] phosphorylation without phosphorylation of FAK [Y397/Y925]. Furthermore, FTY720 conditioned the phosphorylation profile of FAK [Y397/Y576/Y925] in hyperglycemic medium to the same pattern observed in normoglycemic medium. FTY720 challenge resulted in small GTPase Rac activation under hyperglycemic conditions, whereas increased Rho activity in hyperglycemic medium was restored to the basal level. Rac protein depletion by small interfering RNA (siRNA) technique completely abolished FTY720-induced FAK [Y576] phosphorylation. These findings strongly suggest the barrier protective effect of FTY720 on HMVEC monolayers in hyperglycemic medium via S1P signaling, further implying the possibility of FTY720 as a therapeutic agent of diabetic vascular disorder.
