[show abstract][hide abstract] ABSTRACT: The pathogenic role of anti-endothelial cell antibodies (AECA) in vascular injury is debated. It was previously shown that many patients with Wegener's granulomatosis (WG) have AECA that react with human kidney microvascular endothelial cells (EC). In addition, during active disease, renal endothelium strongly expresses the inflammatory molecules vascular adhesion protein-1 (VAP-1) and MHC class I-related antigen A (MICA). This study sought to determine whether AECA mediates this upregulation of VAP-1 and MICA and to define better the signaling pathways that are activated by these autoantibodies upon binding to EC in the kidney. Stimulation of human kidney microvascular EC with AECA IgG upregulated surface expression of MICA and VAP-1, elicited a rapid Ca2+ flux, induced high levels of the chemokines monocyte chemoattractant protein-1 and granulocyte chemotactic protein-2, induced specific phosphorylation of stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) and the transcription factors c-Jun and activating transcription factor-2, and activated NF-kappaB. Specific inhibitors of SAPK/JNK significantly reduced AECA-induced chemokine production and phosphorylation of c-Jun and activating transcription factor-2 and abrogated protein expression of MICA but not VAP-1. In kidney sections from patients with WG, infiltrating cells that expressed the ligand for MICA (NKG2D+) were identified, as were CD8+ and 32 gamma delta+ T cells. In conclusion, AECA may be involved in the pathogenesis of WG, and the SAPK/JNK pathway and the endothelial inflammatory protein VAP-1 may be novel therapeutic targets for vasculitis.
Journal of the American Society of Nephrology 10/2007; 18(9):2497-508. · 8.99 Impact Factor
[show abstract][hide abstract] ABSTRACT: We describe a female patient who, despite negative conventional cross-matches, lost her first kidney graft in an acute humoral rejection. Prior to the second, AB0-incompatible (A1B to A1) living-donor kidney transplant, the patient had negative T- and B-cell cross-matches but had a positive donor-reactive endothelial cell cross-match. Following pre-transplant protein A and GlycoSorb-ABO immunoadsorptions to remove blood group B and anti-endothelial cell antibodies, Mabthera, and IVIG administrations, she was successfully transplanted. By the second post-operative day, creatinine levels were down to 96 micromol/L from 611 micromol/L pre-operatively. On day 9 creatinine rose again, and on the same day the endothelial cell crossmatch became positive for IgG, whereas the T-cell cross-match remained negative and the anti-A1B titers remained low. A kidney biopsy taken on day 10 post-transplant showed a picture of an acute vascular, antibody-mediated rejection. Following rejection treatment and repeated protein A and Glyco-Sorb-ABO immunoadsorptions, the patient's kidney function was again normalized. The use of a recently developed kit (XM-ONE) for the detection of anti-endothelial cell antibodies allowed us to identify a patient at risk for developing acute antibody-mediated rejection as well as to monitor treatment efficacy and post-transplant complications.
[show abstract][hide abstract] ABSTRACT: The monocyte population in blood is considered a possible source of endothelial precursors. Because endothelial-specific receptor tyrosine kinases act as regulators of endothelial cell function, we investigated whether expression of the vascular endothelial growth factor receptor-2 (VEGFR-2) on monocytes is important for their endothelial-like functional capacity. Peripheral-blood monocytes expressing vascular endothelial growth factor receptor-2 (VEGFR-2), or CD14+/VEGFR-2+, were isolated, and their phenotypic, morphologic, and functional capacities were compared with those of monocytes negative for this marker (CD14+/VEGFR-2-). CD14+/VEGFR-2+ cells constituted approximately 2% +/- 0.5% of the total population of monocytes and 0.08% +/- 0.04% of mononuclear cells in blood. CD14+/VEGFR-2+ cells exhibited the potential to differentiate in vitro into cells with endothelial characteristics. The cells were efficiently transduced by a lentiviral vector driving expression of the green fluorescence protein (GFP). Transplantation of GFP-transduced cells into balloon-injured femoral arteries of nude mice significantly contributed to efficient reendothelialization. CD14+/VEGFR-2- did not exhibit any of these characteristics. These data demonstrate that the expression of VEGFR-2 on peripheral blood monocytes is essential for their endothelial-like functional capacity and support the notion of a common precursor for monocytic and endothelial cell lineage. Our results help clarify which subpopulations may restore damaged endothelium and may participate in the maintenance of vascular homeostasis.
[show abstract][hide abstract] ABSTRACT: Impaired angiogenic function has been reported in patients with kidney failure. During vascular damage, endothelial cells may detach from the site of inflammation and be released into the peripheral blood. With the use of Wegener's granulomatosis as a study model, whether circulating inflammatory endothelial cells (IEC) can (1) be used as a disease activity marker and (2) contribute to sustained vascular damage by inducing endothelial progenitor cell (EPC) dysfunction were examined. IEC-defined as endothelial cells that express the two inflammatory-associated markers vascular-adhesion protein-1 (VAP-1) and MHC class I-related chain A (MICA)-were increased significantly in patients with active disease as compared with those in remission. IEC expressed high levels of inducible nitric oxide synthase and neutrophil-activating chemokines, such as macrophage inflammatory protein-1alpha, growth-related oncogene-alpha, epithelial neutrophil activating peptide-78, and IL-8, and induced increased neutrophil migration. IEC levels significantly correlated with C-reactive protein and extent of organ involvement. Patients with active disease had decreased numbers of EPC colony-forming units and a high expression of VAP-1 and MICA in kidney endothelium. EPC did not express VAP-1 or MICA. IEC significantly inhibited proliferation, migration, and endothelial nitric oxide synthase expression in EPC. Thus, apart from being a new disease activity marker, IEC may contribute to vascular damage by impairing the functional capacity for repair by EPC. IEC may provide a unique in vitro system to study pathogenesis of kidney and vascular diseases.
Journal of the American Society of Nephrology 11/2005; 16(10):3110-20. · 8.99 Impact Factor