Abstract. Injury to a target organ can be sensed by bone marrow stem cells that migrate to the site of damage, undergo differentiation, and promote structural and functional repair. This remarkable stem cell capacity prompted an investigation of the potential of mesenchymal and hematopoietic stem cells to cure acute renal failure. The model of renal injury induced in mice by the anticancer agent cisplatin was chosen.

This study showed that patients with CHF may have intestinal overgrowth of pathogenic bacteria and Candida species and increased IP associated with clinical disease severity, venous blood congestion, and inflammation.

We addressed the role of hyperglycemia in leukocyte-endothelium interaction under flow conditions by exposing human umbilical vein endothelial cells for 24 h to normal (5 mM), high concentration of glucose (30 mM), advanced glycosylation end product-albumin (100 microg/ml), or hyperglycemic (174-316 mg/dl) sera from patients with diabetes and abnormal hemoglobin A1c (8.1+/-1.4%). At the end of incubation endothelial cells were perfused with total leukocyte suspension in a parallel plate flow chamber under laminar flow (1.5 dyn/cm2). Rolling and adherent cells were evaluated by digital image processing. Results showed that 30 mM glucose significantly (P < 0. 01) increased the number of adherent leukocytes to endothelial cells in respect to control (5 mM glucose; 151+/-19 versus 33+/-8 cells/mm2). A similar response was induced by endothelial stimulation with IL-1beta, here used as positive control (195+/-20 cells/mm2). The number of rolling cells on endothelial surface was not affected by high glucose level. Stable adhesion of leukocytes to glucose-treated as well as to IL-1beta-stimulated endothelial cells was preceded by short interaction of leukocytes with the endothelial surface. The distance travelled by leukocytes before arrest on 30 mM glucose, or on IL-1beta-treated endothelial cells, was significantly (P < 0.01) higher than that observed for leukocytes adhering on control endothelium (30 mM glucose: 76.7+/-3.5; IL1beta: 69.7+/-4 versus 5 mM glucose: 21.5+/-5 microm). Functional blocking of E-selectin, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1 on endothelial cells with the corresponding mouse mAb significantly inhibited glucose-induced increase in leukocyte adhesion (67+/-16, 83+/-12, 62+/-8 versus 144+/-21 cells/ mm2). Confocal fluorescence microscopy studies showed that 30 mM glucose induced an increase in endothelial surface expression of E-selectin, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1. Electrophoretic mobility shift assay of nuclear extracts of human umbilical vein endothelial cells (HUVEC) exposed for 1 h to 30 mM glucose revealed an intense NF-kB activation. Treatment of HUVEC exposed to high glucose with the NF-kB inhibitors pyrrolidinedithiocarbamate (100 microM) and tosyl-phe-chloromethylketone (25 microM) significantly reduced (P < 0.05) leukocyte adhesion in respect to HUVEC treated with glucose alone. A significant (P < 0.01) inhibitory effect on glucose-induced leukocyte adhesion was observed after blocking protein kinase C activity with staurosporine (5 nM). When HUVEC were treated with specific antisense oligodesoxynucleotides against PKCalpha and PKCepsilon isoforms before the addition of 30 mM glucose, a significant (P < 0.05) reduction in the adhesion was also seen. Advanced glycosylation end product-albumin significantly increased the number of adhering leukocytes in respect to native albumin used as control (110+/-16 versus 66+/-7, P < 0.01). Sera from diabetic patients significantly (P < 0.01) enhanced leukoc...

Effacement of podocyte foot processes occurs in many proteinuric nephropathies and is accompanied by rearrangement of the actin cytoskeleton. Here, we studied whether protein overload affects intracellular pathways, leading to cytoskeletal architecture changes and ultimately to podocyte dysfunction. Mouse podocytes bound and endocytosed both albumin and IgG via receptor-specific mechanisms. Protein overload caused redistribution of F-actin fibers instrumental to up-regulation of the prepro-endothelin (ET)-1 gene and production of the corresponding peptide. Increased DNA-binding activity for nuclear factor (NF)-kappaB and Ap-1 nuclear proteins was measured in nuclear extracts of podocytes exposed to excess proteins. Both Y27632, which inhibits Rho kinase-dependent stress fiber formation, and jasplakinolide, an F-actin stabilizer, decreased NF-kappaB and Ap-1 activity and reduced ET-1 expression. This suggested a role for the cytoskeleton, through activated Rho, in the regulation of the ET-1 peptide. Focal adhesion kinase (FAK), an integrin-associated nonreceptor tyrosine kinase, was phosphorylated by albumin treatment via Rho kinase-triggered actin reorganization. FAK activation led to NF-kappaB- and Ap-1-dependent ET-1 expression. These data suggest that reorganization of the actin cytoskeletal network in response to protein load is implicated in modulation of the ET-1 gene via Rho kinase-dependent FAK activation of NF-kappaB and Ap-1 in differentiated podocytes. Increased ET-1 generation might alter glomerular permselectivity and amplify the noxious effect of protein overload on dysfunctional podocytes.

Chronic diseases of the kidney have a progressive course toward organ failure. Common pathway mechanisms of progressive injury, irrespectively of the etiology of the underlying diseases, include glomerular capillary hypertension and enhanced passage of plasma proteins across the glomerular capillary barrier because of impaired permselective function. These changes are associated with podocyte injury and glomerular sclerosis. Direct evidence for causal roles is lacking, particularly for the link between intraglomerular protein deposition and sclerosing reaction. Because transforming growth factor-beta1 (TGF-beta1) is the putative central mediator of scarring, we hypothesized that TGF-beta1 can be up-regulated by protein overload of podocytes thereby contributing to sclerosis. In rats with renal mass reduction, protein accumulation in podocytes as a consequence of enhanced transcapillary passage preceded podocyte dedifferentiation and injury, increase in TGF-beta1 expression in podocytes, and TGF-beta1-dependent activation of mesangial cells. Angiotensin-converting enzyme inhibitor prevented both accumulation of plasma proteins and TGF-beta1 overexpression in podocytes and sclerosis. Albumin load on podocytes in vitro caused loss of the synaptopodin differentiation marker and enhanced TGF-beta1 mRNA and protein. Conditioned medium of albumin-stimulated podocytes induced a sclerosing phenotype in mesangial cells, an effect mimicked by TGF-beta1 and blocked by anti-TGF-beta1 antibodies. Thus, the passage of excess plasma proteins across the glomerular capillary wall is the trigger of podocyte dysfunction and of a TGF-beta1-mediated mechanism underlying sclerosis. Agents to reduce TGF-beta1, possibly combined with angiotensin blockade, should have priority in novel approaches to treatment of progressive nephropathies.

Stx-2 via a transcriptional activation mechanism specifically mediated by NF-kappaB up-regulates endothelial MCP-1 and IL-8. Both chemokines are important modulators of leukocyte adhesion and transmigration under flow. These findings might be relevant to understand the nature of microvascular lesions in HUS and open future perspectives for better treatment of microvascular thrombosis.

Ameliorating the function of the glomerular barrier to circulating proteins by blocking angiotensin II (Ang II) translates into less risk of progression toward endstage renal failure in diabetic and nondiabetic nephropathies. However, the mechanisms underlying this barrier protection are not clear. Specialized contacts between adjacent podocytes are major candidate targets, and the actin cytoskeleton is emerging as a regulatory element. Here, we present data demonstrating that Ang II induced reorganization of F-actin fibers and redistribution of zonula occludens-1 (ZO-1) that is physically associated with actin in murine podocytes. These effects were paralleled by increased albumin permeability across podocyte monolayers. The F-actin stabilizer jasplakinolide prevented both ZO-1 redistribution and albumin leakage, suggesting that actin cytoskeleton rearrangement is instrumental to podocyte permselective dysfunction induced by Ang II. Changes in both F-actin and ZO-1 patterns were confirmed in glomeruli of rat isolated perfused kidneys on short infusion of Ang II, leading to increased protein excretion. Podocyte dysfunction was mediated by Ang II type 1 receptor and was partly dependent on Src kinase-phospholipase C activation. These data demonstrate that strategies aimed at stabilizing podocyte-podocyte contacts and targeting the relevant intracellular signal transduction are crucial to renoprotection.

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