Mechanisms of endothelial cell injury in vasculitis

Adalimumab therapy in hepatitis B virus-negative polyarteritis nodosa: A case report

INTRODUCTION

Polyarteritis nodosa (PAN) is a difficult-to-treat rheumatology disorder, and biologic agents have been used in such patients with a treatment failure or the disease relapse.

CASE PRESENTATION

We report a 42-year-old male Han Chinese who received adalimumab (ADA) alone during his vasculitis relapse, manifesting with weight loss, ankle arthritis, testicular inflammation and new-onset hypertension. Under the ADA 40 mg biweekly subcutaneous injection, there were the disappearance of clinical activity and no disease flares with a follow-up period of 26 months.

CONCLUSION

The clinical observation in this patient suggests a potential efficacy of ADA therapy in controlling the disease activity of PAN.

The Successful Treatment of Refractory Polyarteritis Nodosa Using Infliximab

Polyarteritis nodosa (PAN), characterized by arteritis of medium-sized blood vessels, is usually treated with a combination of glucocorticoids and immunosuppressants; however, some cases are refractory to these treatments. We herein report the case of a man with PAN that was refractory to various immunosuppressive treatments, including cyclophosphamide, methotrexate, and rituximab. After infliximab (IFX) treatment was initiated, his symptoms improved dramatically and remission was maintained. IFX is considered to be an effective alternative treatment for PAN which proves to be refractory to several immunosuppressive treatments.

Upper respiratory tract symptoms, renal involvement and vasculitis: a case report and review of wegener granulomatosis

Wegener’s Granulomatosis is a condition associated with systemic vasculitis which can present with upper respiratory tract symptoms initially. On September 2001, a 15-year-old girl presented with symptoms of nasal block for 3 weeks. She later developed joint pains and worsening renal status requiring dialysis. A renal biopsy was performed which showed pauci-immune cresentric glomerulonephritis. Her cANCA levels were positive. She was treated with oral cyclophosphamide and steroids and later responded.

Evidence for a novel human-specific xeno-auto-antibody response against vascular endothelium

Humans are genetically unable to synthesize the common mammalian sialic acid N-glycolylneuraminic acid (Neu5Gc). However, Neu5Gc can be metabolically incorporated and covalently expressed on cultured human cell surfaces. Meanwhile, humans express varying and sometimes high titers of polyclonal anti-Neu5Gc antibodies. Here, a survey of human tissues by immunohistochemistry with both a monospecific chicken anti-Neu5Gc antibody and with affinity-purified human anti-Neu5Gc antibodies demonstrates endothelial expression of Neu5Gc, likely originating from Neu5Gc-rich foods like red meats. We hypothesized that the combination of Neu5Gc incorporation and anti-Neu5Gc antibodies can induce endothelial activation. Indeed, the incubation of high-titer human sera with Neu5Gc-fed endothelial cells led to Neu5Gc-dependent antibody binding, complement deposition, endothelial activation, selectin expression, increased cytokine secretion, and monocyte binding. The proinflammatory cytokine tumor necrosis factor-alpha also selectively enhanced human anti-Neu5Gc antibody reactivity. Anti-Neu5Gc antibodies affinity-purified from human serum also directed Neu5Gc-dependent complement deposition onto cultured endothelial cells. These data indicate a novel human-specific mechanism in which Neu5Gc-rich foods deliver immunogenic Neu5Gc to the endothelium, giving anti-Neu5Gc antibody- and complement-dependent activation, and potentially contributing to human vascular pathologies. In the case of atherosclerosis, Neu5Gc is present both in endothelium overlying plaques and in subendothelial regions, providing multiple pathways for accelerating inflammation in this disease.

Variable incidence of cyclosporine and FK-506 neurotoxicity in hematopoeitic malignancies and marrow conditions after allogeneic bone marrow transplantation

INTRODUCTION

This study examines whether malignant disease under treatment influences the incidence of cyclosporine or FK-506 neurotoxicity after myeloablative conditioning and allogeneic bone marrow transplantation (allo-BMT).

METHODS

Review of 290 patients who received myeloablative conditioning prior to allo-BMT and cyclosporine/FK-506 identified 21 (7.2%) patients with neurotoxicity confirmed by computed tomography or magnetic resonance. Underlying malignancy necessitating allo-BMT included leukemias (67%), lymphoma (10%), myelodysplastic syndrome (10%), and multiple myeloma (MM). Frequency of neurotoxicity by disease was compared.

RESULTS

The highest incidence of neurotoxicity was present with MM (25%), whereas the lowest incidence was present with lymphoma (2.7%). Other diseases demonstrated intermediate incidence, including acute leukemias (10%), myelodysplastic syndrome (6.4%), and chronic myelogenous leukemia (4.9%).

CONCLUSION

Cyclosporine/FK-506 neurotoxicity varied according to the underlying malignancy. The variable susceptibility to the development of neurotoxicity in this population may depend on the interaction of host vasculature with disease specific factors. Understanding the cause of neurotoxicity could improve survival after allo-BMT.

Kinetics of thrombomodulin release and endothelial cell injury by neutrophil-derived proteases and oxygen radicals

Thrombomodulin is a transmembranous glycoprotein of endothelial cells. In vitro it is a marker of endothelial cell injury. In vivo the levels of serum thrombomodulin are regarded as a parameter of activity in vasculitides. The latter are pathophysiologically determined by neutrophil-derived inflammation and endothelial cell injury caused by secretion of proteases and hydrogen peroxide. It was the objective of this study to determine whether thrombomodulin is only a late marker of advanced endothelial cell injury or whether it indicates also earlier stages of cell alterations. Over 24 hr endothelial cell cultures were incubated with hydrogen peroxide or the neutrophil proteases proteinase-3, elastase and cathepsin G. The time-dependent increase of thrombomodulin in the supernatant was determined by enzyme-linked immunosorbent assay and immunoblot. In addition the viability (eosin, tetrazolium dye assay), detachment (crystal-violet assay), and apoptosis (4',6-diamine-2'-phenylindole-dihydrochloride assay) of the respective endothelial cells were determined for adherent and non-adherent cells. A rapid thrombomodulin increase was found under all experimental conditions. The additional immunoblotting analysis showed the pattern of proteolytic cleavage caused by the protease reactivity. In case of hydrogen peroxide the thrombomodulin increase was closely correlated with the loss of cell viability and lysis. The incubation of endothelial cells with the different proteases resulted in a time-dependent detachment of primarily viable cells. In addition to cell necrosis apoptotic cell death was found in the subgroup of detached endothelial cells after prolonged incubation over 24 hr with proteinase-3 (23%), elastase (31%), and cathepsin G (19%). In contrast, still adhering cells did not show any signs of necrosis or apoptosis. In summary these studies confirm in vitro that soluble thrombomodulin is not only a parameter of advanced endothelial cell destruction itself but also in addition an early marker of initial endothelial cell membrane changes induced by neutrophil derived proteases and oxygen radicals.

Antineutrophil cytoplasm autoantibodies from patients with systemic vasculitis activate neutrophils through distinct signaling cascades: comparison with conventional Fcgamma receptor ligation

In systemic vasculitis, interactions between antineutrophil cytoplasm autoantibodies (ANCAs) and neutrophils initiate endothelial and vascular injury. ANCAs directed against either myeloperoxidase (MPO) or proteinase 3 (PR3) can activate cytokine-primed neutrophils by binding cell surface-expressed MPO or PR3, with the concurrent engagement of Fcgamma receptors (FcgammaR). Because roles for phospholipase D (PLD) and phosphatidylinositol 3 kinase (PI3K) have been demonstrated in FcgammaR activation of neutrophils, this study investigated the hypothesis that ANCA stimulation of neutrophils involved a similar engagement of FcgammaR and activation of PLD and PI3K. Pretreatment of tumor necrosis factor (TNF) alpha-primed neutrophils with antibodies against FcgammaRII and FcgammaRIII inhibited MPO-ANCA and PR3-ANCA induced superoxide generation, confirming that FcgammaR ligation is involved in ANCA-mediated neutrophil activation. However, although stimulation of TNF-alpha-primed neutrophils by conventional FcgammaR ligation, either using antibody-mediated cross-linking of FcgammaR or aggregated IgG, induced PLD activation, ANCA stimulation did not. Moreover, although ANCA-induced neutrophil activation results in significant PI3K activation-as assessed by phosphatidylinositol 3,4,5-triphosphate generation-conventional FcgammaR ligation, but not ANCA, activates the p85/p110 PI3K subtype. Inhibition of ANCA-induced superoxide generation with pertussis toxin suggests that ANCAs activate the p101/p110gamma PI3K isoform. In addition, the kinetics of activation of protein kinase B differs between conventional FcgammaR ligation and ANCA stimulation of neutrophils. These results demonstrate that though ligation of FcgammaRIIa and FcgammaRIIIb may be necessary, it is likely that ANCAs require other membrane cofactors for neutrophil activation.

Interaction of endothelial cells and neutrophils in vitro: kinetics of thrombomodulin, intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1): implications for the relevance as serological disease activity markers in vasculitides

Recently markers of endothelial cell activation or injury gained increasing interest as serological parameters of disease activation in vasculitides. Among these, soluble serum thrombomodulin, ICAM-1, VCAM-1 and E-selectin are of particular interest. However, only thrombomodulin showed the expected close correlation. The objective of this study was to investigate in vitro the kinetics of these endothelial cell receptors after interaction of unstimulated or cytokine-activated polymorphonuclear neutrophils (PMN) and endothelial cells in order to find evidence explaining these different clinical findings. Over the time period of up to 48 h of incubation the kinetics of thrombomodulin, ICAM-1, E-selectin, and VCAM-1 levels in the supernatant of endothelial cells in co-culture with neutrophils were determined in vitro by ELISA under basal and partially cytokine-activated (tumour necrosis factor-alpha) conditions. Increased levels of ICAM-1, E-selectin and VCAM-1 were already found due to cytokine activation of endothelial cells alone. This increase was augmented after coincubation with neutrophils. In contrast, a significant increase of thrombomodulin in the supernatant was only found due to cell injury after cell-cell interaction of cytokine-activated endothelial cells with neutrophils. In conclusion, this in vitro model of the kinetics of soluble endothelial cell receptors after cell-cell interaction of cytokine-activated PMN and endothelial cells underlines the advantage of thrombomodulin in contrast to the adhesion molecules as a marker of endothelial damage. Therefore, soluble thrombomodulin seems to be a promising, valuable serological disease activity marker in vasculitides.

Prevention of crescentic glomerulonephritis by immunoneutralization of the fractalkine receptor CX3CR1 rapid communication

BACKGROUND

Fractalkine is a newly identified T-cell and monocyte/macrophage (Mphi) chemokine with a transmembrane domain and is a cell-surface protein on activated endothelium. It can mediate adhesion of cells expressing the fractalkine receptor CX3CR1. These unique features make fractalkine well suited for leukocyte recruitment in tissues with high blood flow as in the renal glomerulus.

METHODS

Fractalkine expression in glomeruli and response of isolated glomerular inflammatory cells to fractalkine were studied in the Wistar-Kyoto (WKY) crescentic glomerulonephritis model. Antibody was used to confirm the proinflammatory role of fractalkine.

RESULTS

Fractalkine was markedly induced in the endothelium of nephritic rat glomeruli, and inflammatory leukocytes infiltrating the glomeruli expressed increased levels of CX3CR1. Anti-CX3CR1 antibody treatment dramatically blocked leukocyte infiltration in the glomeruli, prevented crescent formation, and improved renal function.

CONCLUSIONS

Fractalkine plays a central role in leukocyte trafficking at the endothelium in the high-flow glomerular circuit and, in turn, implicates CX3CR1 as a prime drug target for therapeutic intervention of endothelium-related inflammatory diseases.

Antineutrophil cytoplasmic antibodies in Wegener's granulomatosis

The prevalence of antineutrophil cytoplasmic antibodies (ANCA) was studied in 12 children with Wegener's granulomatosis. The serum samples were taken in the active phase of disease and were screened for ANCA by indirect immunofluorescence with normal neutrophils and enzyme linked immunosorbent assay (ELISA) using crude neutrophil extract, proteinase 3, myeloperoxidase, cathepsin G, lactoferrin, and elastase as antigens. Of these 12 patients, 10 wre positive for ANCA in the active phase of their illness, and they showed a predominantly cytoplasmic ANCA staining pattern on indirect immunofluorescence. There were high titres of ANCA directed against crude neutrophil extract, proteinase 3, myeloperoxidase, and cathepsin G. IgM isotypes occurred as commonly as IgG isotypes. Therefore, screening for ANCA is usually but not invariably positive in children with Wegener's granulomatosis. Specific diagnosis still relies on clinical and pathological features, and the value of ANCA in the diagnosis of paediatric Wegener's granulomatosis requires further study.

A new model of renal microvascular injury

The vascular endothelial injury with its consequent activation is actively involved in inflammation and promotion of a procoagulant state, which are likely to be of major importance in the pathogenesis of various disorders, including renal thrombotic microangiopathy. This study briefly reviews the consequences of glomerular endothelial cell injury or activation, as shown by recent experimental data.

Platelet-Derived Interleukin-1 Induces Cytokine Production, but not Proliferation of Human Vascular Smooth Muscle Cells

During vascular injury, such as observed in atherosclerosis, restenosis, vasculitides, transplantation, or sepsis, vascular smooth muscle cells (SMC) can be exposed to platelets or platelet products. Under these conditions proliferation or cytokine production of SMC stimulated by platelets or platelet products may contribute to regulation of vascular pathogenesis. Thus, we investigated interleukin-6 (IL-6) and IL-8 production as well as proliferation of SMC in response to platelets or platelet lysates. Platelets not already preactivated by thrombin induced IL-6 (10- to 50-fold) or IL-8 production of unstimulated SMC in a cell number dependent fashion. Preactivation of platelets with thrombin potently increased the platelet-mediated IL-6 (50- to 1,000-fold) and IL-8 production of SMC. Hirudin specifically inhibited the activation of platelets with thrombin. Isolated platelets cultured in the absence of SMC did not contain detectable IL-6 or IL-8. Prestimulation (4 hours) of SMC with pathophysiologically relevant substances (lipopolysaccharide [LPS], tumor necrosis factor-α [TNF-α], or IL-1α) further increased the platelet-induced cytokine production. The platelet-derived SMC stimulatory activity was IL-1, since IL-1 receptor antagonist (IL-1-Ra) inhibited the platelet-induced cytokine production of SMC. Anti-platelet-derived growth factor (PDGF)-antibody did not further reduce this activity. Thrombin itself stimulated expression of IL-6 and IL-8 to some degree and induced IL-6 production of SMC synergistically with IL-1. Platelets also induced proliferation of SMC, however, anti-PDGF antibodies, rather than IL-1-Ra blocked this response. These data show that platelet-derived IL-1 stimulates cytokine production of vascular smooth muscle cells, indicating that platelet-derived IL-1 may contribute to regulation of local pathogenesis in the vessel wall by activation of the cytokine regulatory network.

Platelet-Derived Interleukin-1 Induces Cytokine Production, but not Proliferation of Human Vascular Smooth Muscle Cells

During vascular injury, such as observed in atherosclerosis, restenosis, vasculitides, transplantation, or sepsis, vascular smooth muscle cells (SMC) can be exposed to platelets or platelet products. Under these conditions proliferation or cytokine production of SMC stimulated by platelets or platelet products may contribute to regulation of vascular pathogenesis. Thus, we investigated interleukin-6 (IL-6) and IL-8 production as well as proliferation of SMC in response to platelets or platelet lysates. Platelets not already preactivated by thrombin induced IL-6 (10- to 50-fold) or IL-8 production of unstimulated SMC in a cell number dependent fashion. Preactivation of platelets with thrombin potently increased the platelet-mediated IL-6 (50- to 1,000-fold) and IL-8 production of SMC. Hirudin specifically inhibited the activation of platelets with thrombin. Isolated platelets cultured in the absence of SMC did not contain detectable IL-6 or IL-8. Prestimulation (4 hours) of SMC with pathophysiologically relevant substances (lipopolysaccharide [LPS], tumor necrosis factor-α [TNF-α], or IL-1α) further increased the platelet-induced cytokine production. The platelet-derived SMC stimulatory activity was IL-1, since IL-1 receptor antagonist (IL-1-Ra) inhibited the platelet-induced cytokine production of SMC. Anti-platelet-derived growth factor (PDGF)-antibody did not further reduce this activity. Thrombin itself stimulated expression of IL-6 and IL-8 to some degree and induced IL-6 production of SMC synergistically with IL-1. Platelets also induced proliferation of SMC, however, anti-PDGF antibodies, rather than IL-1-Ra blocked this response. These data show that platelet-derived IL-1 stimulates cytokine production of vascular smooth muscle cells, indicating that platelet-derived IL-1 may contribute to regulation of local pathogenesis in the vessel wall by activation of the cytokine regulatory network.

A new model of renal microvascular endothelial injury

Although the importance of injury with consequent activation of endothelium is well-recognized in diseases affecting the glomerular endothelial cell (GEN), research on GEN injury in vivo has been hampered by the lack of adequate animal models. Here we report the establishment and characterization of a new GEN injury model in rats. This model was induced by selective renal artery perfusion with anti-GEN IgG and resulted in the severe acute renal failure with marked platelet deposition and development of a thrombotic microangiopathy involving glomeruli. Peritubular capillary endothelial cells were also damaged that was associated with severe tubular necrosis. Although the glomerular changes were severe, half of the glomeruli recovered by day 10, while interstitial changes remained throughout our observation time course. Proliferation of GEN was observed during the recovery phase. An increased expression of endothelial nitric oxide synthase in GEN was also observed, and may be an adaptive mechanism to counteract the thrombosis and ischemia. This model should be useful to investigate the pathophysiology of renal microvascular diseases and the mechanisms of GEN injury, activation and recovery in vivo.

S-Endo 1, a pan-endothelial monoclonal antibody recognizing a novel human endothelial antigen

A murine monoclonal antibody (mAb) S-Endo 1 has been produced to detect circulating endothelial cells detached from blood vessels in pathological conditions. We have demonstrated that the associated-antigen (S-Endo 1 Ag) was highly expressed on human vascular structure irrespective of tissue origin or vessel caliber. Its expression was not restricted to endothelium, since it was also detected at low level on smooth muscle cells, stroma cells and follicular dendritic cells. But its absence on hematopoietic cells made S-Endo 1 a helpful reagent to specifically discriminate endothelium from hematopoietic tissues. Biochemical characterization showed that S-Endo 1 recognizes a monomeric structure of approximately 118 kDa on cultured endothelial cells. S-Endo 1 was submitted to the 5th International Workshop (Boston, 1993) and did not cluster in any of the old or new endothelial clusters discussed at the conference, indicating its unique reactivity. Together with the data presented in this paper, this suggested that S-Endo 1 defines a previously undescribed endothelial molecule.

Endothelial cells and renal epithelial cells do not express the Wegener's autoantigen, proteinase 3

Proteinase 3 (PR3) is the major antigen for autoantibodies (C-ANCA) against cytoplasmic components of neutrophils which are strongly associated with Wegener's granulomatosis (WG). Recent data that PR3 may be expressed by renal tubular epithelial cells and endothelial cells suggest potential for a direct pathogenic effect against these cells by C-ANCA or cytoxic T lymphocytes. Using a semi-quantitative polymerase chain reaction (PCR), ELISA and indirect immunofluorescence staining we studied endothelial and epithelial cell PR3 expression. By PCR, no PR3 expression was found in human umbilical vein endothelial cells (HUVEC) either untreated, or when treated with interferon-gamma (IFN-gamma) (200 U/ml, 6 h, 24 h), IL-1 (20 U/ml, 6 h), tumour necrosis factor-alpha, (TNF-alpha) (200 U/ml, 0, 1, 2, 4, 6 h) or IFN-gamma + TNF-alpha (6 h); iliac vein and artery endothelial cells did not express PR3 either. In contrast, PR3 was detected in HL60 cells and neutrophils by PCR, expression being confirmed by sequence analysis. Three PR3 MoAbs showed no binding to unstimulated or TNF-alpha-stimulated HUVEC either by ELISA or by indirect immunofluorescence staining. The epithelial cell line A549 expressed PR3 when assayed by PCR. However, three renal epithelial cell lines (two tubular and one glomerular) showed little or no PR3 expression by PCR or ELISA. These studies fail to demonstrate evidence for PR3 expression by endothelial cells, even when using the highly sensitive PCR assay. Whilst PR3 expression by A549 cells is intriguing, the relevance of this in the pathology of WG is doubtful considering the negligible expression by renal epithelial cell lines.