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BACKGROUND The standard therapy in acquired thrombotic thrombocytopenic purpura (TTP) is plasma exchange. In unresponsive TTP, intensification of plasma exchange and immunomodulatory therapy can be initiated but it can be complicated to select for patients that will benefit from intensification. CASE REPORT We describe two cases of newly diagnosed TTP with a complicated clinical course during initial treatment with plasma exchange. In one case, after an initial response to plasma exchange, a decrease in platelet count was observed on Day 7. The normalized ADAMTS13 activity guided the clinicians in the diagnosis of a concurrent heparin-induced thrombocytopenia due to the heparin lock, used for the indwelling catheter. The other case with TTP clinically deteriorated early during initial treatment. Reevaluation on Day 5, including ADAMTS13 activity, which was undetectably low, supported the clinical decision to intensify the plasma exchange to twice daily and start with the immunomodulating agent rituximab. In both clinically complicated cases measurements of ADAMTS13 activity during plasma exchange proved to be useful in guiding treatment decisions. CONCLUSION Serial measurements of ADAMTS13 activity should be considered in patients with newly diagnosed TTP with an unpredictable clinical course during initial therapeutic plasma exchange. These measurements may provide pivotal clinical insights on appropriate patient management.

Objective: The clinical relevance of lower basal cortisol levels in children with asthma is unclear. We compared the salivary cortisol response after a standardized exercise test in children with asthma versus the salivary cortisol response in healthy children.Methods: Nineteen prepubertal children with asthma and 20 prepubertal healthy children performed a standardized exercise test twice. Salivary cortisol levels were determined before exercise and immediately and 15 min after exercise. Morning salivary cortisol levels were determined from saliva collected at home.Results: Salivary cortisol levels increased in 84.2% of the healthy children compared to 35.0% in children with asthma after the 20-m shuttle-run test. Median increase in salivary cortisol levels was 200.3% [95% confidence interval (CI), 141.8-346.1] in healthy children compared to 89.8% (95% CI, 56.9-181.6) in children with asthma. The response was not related to the morning salivary cortisol level or maintenance dose of inhaled corticosteroids. The mean time to exhaustion of both shuttle-run tests was significantly shorter in children with asthma (mean difference 1.4 min; 95% CI, 0.7-2.3). None of the children had to stop because of dyspnea.Conclusion: Our study demonstrates that children with asthma using a maintenance dose of inhaled corticosteroids (ICS) have an attenuated salivary cortisol response compared with healthy children.

Objective: To determine the feasibility of non-invasive evaluation of adrenal response in healthy prepubertal children by standardized exercise tests.Methods: On separate occasions, healthy prepubertal children performed a submaximal cycling test, a maximal cycling test, and a 20-m shuttle-run test. Salivary cortisol levels were determined before exercise, and 1 and 15 min after exercise.Results: Immediately after cessation of the cycling and shuttle-run tests, salivary cortisol levels remained unchanged or decreased. Fifteen minutes after the shuttle-run test, salivary cortisol levels increased significantly. This increase in salivary cortisol levels was not observed 15 min after the cessation of the cycling tests.Conclusion: The results of this study demonstrate a different response in salivary cortisol levels after standardized cycling and running tests in prepubertal children. The increase in salivary cortisol levels found after a short standardized running test suggests that this may be a practical non-invasive method for evaluating adrenal response in healthy prepubertal children.

Antimyeloperoxidase antibodies can cause crescentic glomerulonephritis and pulmonary hemorrhage. Toll-like receptors (TLRs) respond to infectious agents activating host defenses, whereas infections potentially initiate disease and provoke relapses. Neutrophils were found to be key effector cells of injury in experimental models, as disease does not occur in their absence and injury is enhanced by lipopolysaccharide (LPS). In this study, highly purified LPS (a pure TLR4 ligand) acted with antimyeloperoxidase antibodies to synergistically increase kidney and lung neutrophil recruitment and functional injury; effects abrogated in TLR4-deficient mice. Increased kidney TLR4 expression after stimulation predominantly occurred in glomerular endothelial cells. Enhanced glomerular neutrophil recruitment correlated with increased kidney mRNA expression of CXCL1 and CXCL2 (homologs of human CXCL8), whereas their preemptive neutralization decreased neutrophil recruitment. Disease induction in bone marrow chimeric mice showed that TLR4 in both bone marrow and renal parenchymal cells is required for maximal neutrophil recruitment and glomerular injury. Further studies in human glomerular cell lines stimulated with LPS found that glomerular endothelial cells were the prominent sources of CXCL8. Thus, our results define a role for TLR4 expression in bone marrow-derived and glomerular endothelial cells in neutrophil recruitment and subsequent functional and histological renal injury in experimental antimyeloperoxidase glomerulonephritis. Kidney International (2010) 78, 1263-1274; doi:10.1038/ki.2010.327; published online 15 September 2010

Objective To determine whether inhibition of p38 mitogen-activated protein kinase (p38MAPK) reduces the pathogenicity of anti-neutrophil cytoplasmic autoantibodies (ANCAs) in vitro and in vivo.Methods The effects of the p38MAPK-specific inhibitor AR-447 were studied in vitro using neutrophil respiratory burst and degranulation assays, and in lipopolysaccharide (LPS)-stimulated human glomerular endothelial cells. In vivo, p38MAPK inhibition was investigated in a mouse anti-myeloperoxidase (MPO) IgG/LPS glomerulonephritis model. Mice were treated orally with AR-447 daily, starting before (pretreatment group) or 24 h after disease onset (treatment group), and killed after 1 or 7 day(s).Results In vitro, AR-447 diminished neutrophil respiratory burst and degranulation induced by patient-derived MPO-ANCA and proteinase 3 (Pr3)-ANCA. In glomerular endothelial cells, AR-447 reduced LPS-induced secretion of IL-6 and IL-8, but not of MCP-1. In mice, pretreatment with AR-447 reduced albuminuria 1 day after induction of glomerulonephritis. After 7 days, no effects on urinary abnormalities were observed upon AR-447 pretreatment or treatment. Also, glomerular neutrophil accumulation was not diminished. In contrast, glomerular macrophage accumulation and the formation of glomerular crescents was significantly reduced by AR-447 pretreatment (vehicle: 12.5 +/- 5.6% crescentic glomeruli; AR-447: 7.7 +/- 2.7%) and treatment (vehicle 14.6 +/- 1.8%; AR-447 6.0 +/- 3.4%) at 7 days.Conclusion This study shows that p38MAPK inhibition markedly reduces ANCA-induced neutrophil activation in vitro. In vivo, p38MAPK inhibition partly reduced crescent formation when the drug was administered prior to disease induction and after disease onset, suggesting that besides p38MAPK activity other signalling pathways contribute to the disease activity.

Anti-neutrophil cytoplasmic autoantibodies (ANCA) directed against myeloperoxidase (MPO) and proteinase 3 (Pr3) are considered pathogenic in ANCA-associated necrotizing and crescentic glomerulonephritis (NCGN) and vasculitis. Modulation of ANCA IgG glycosylation may potentially reduce its pathogenicity by abolishing Fc receptor mediated activation of leukocytes and complement Here, we investigated whether IgG hydrolysis by the bacterial enzyme endoglycosidase S (EndoS) attenuates ANCA-mediated NCGN. In vitro, treatment of ANCA IgG with EndoS significantly attenuated ANCA-mediated neutrophil activation without affecting antigen-binding capacity. In a mouse model of antiMPO IgG/LPS-induced NCGN, we induced disease with either unmodified or EndoS-treated (deglycosylated) anti-MPO IgG. In separate experiments, we administered EndoS systemically after disease induction with unmodified anti-MPO IgG. Pretreatment of anti-MPO IgG with EndoS reduced hematuria, leukocyturia, and albuminuria and attenuated both neutrophil influx and formation of glomerular crescents After inducing disease with unmodified anti-MPO IgG, systemic treatment with EndoS reduced albuminuria and glomerular crescent formation when initiated after 3 but not 24 hours. In conclusion, IgG glycan hydrolysis by EndoS attenuates ANCA-induced neutrophil activation in vitro and prevents induction of anti-MPO IgG/LPS-mediated NCGN m vivo. Systemic treatment with EndoS early after disease induction attenuates the development of disease. Thus, modulation of IgG glycosylation is a promising strategy to interfere with ANCA-mediated inflammatory processes.

Myeloperoxidase (MPO) is a heme-containing peroxidase abundantly expressed in neutrophils and to a lesser extent in monocytes. Enzymatically active MPO, together with hydrogen peroxide and chloride, produces the powerful oxidant hypochlorous acid and is a key contributor to the oxygen-dependent microbicidal activity of phagocytes. In addition, excessive generation of MPO-derived oxidants has been linked to tissue damage in many diseases, especially those characterized by acute or chronic inflammation. It has become increasingly clear that MPO exerts effects that are beyond its oxidative properties. These properties of MPO are, in many cases, independent of its catalytic activity and affect various processes involved in cell signaling and cell-cell interactions and are, as such, capable of modulating inflammatory responses. Given these diverse effects, an increased interest has emerged in the role of MPO and its downstream products in a wide range of inflammatory diseases. In this article, our knowledge pertaining to the biologic role of MPO and its downstream effects and mechanisms of action in health and disease is reviewed and discussed. Antioxid. Redox Signal. 11, 2899-2937.

The standard therapy in acquired thrombotic thrombocytopenic purpura (TTP) is plasma exchange. In unresponsive TTP, intensification of plasma exchange and immunomodulatory therapy can be initiated but it can be complicated to select for patients that will benefit from intensification.We describe two cases of newly diagnosed TTP with a complicated clinical course during initial treatment with plasma exchange. In one case, after an initial response to plasma exchange, a decrease in platelet count was observed on Day 7. The normalized ADAMTS13 activity guided the clinicians in the diagnosis of a concurrent heparin-induced thrombocytopenia due to the heparin lock, used for the indwelling catheter. The other case with TTP clinically deteriorated early during initial treatment. Reevaluation on Day 5, including ADAMTS13 activity, which was undetectably low, supported the clinical decision to intensify the plasma exchange to twice daily and start with the immunomodulating agent rituximab. In both clinically complicated cases measurements of ADAMTS13 activity during plasma exchange proved to be useful in guiding treatment decisions.Serial measurements of ADAMTS13 activity should be considered in patients with newly diagnosed TTP with an unpredictable clinical course during initial therapeutic plasma exchange. These measurements may provide pivotal clinical insights on appropriate patient management.

Most end-stage renal disease kidneys display accumulation of extracellular matrix (ECM) in the renal tubular compartment (tubular interstitial fibrosis - TIF) which is strongly correlated with the future loss of renal function. Although inflammation is a key event in the development of TIF, it can also have a beneficial anti-fibrotic role depending in particular on the stage of the pathology. Chemokines play an important role in monocyte extravasation in the inflammatory process. CCL2 has already been shown to be involved in the development of TIF but CCL7, a close relative of CCL2 and able to bind to similar receptors, has not been studied in renal disease. We therefore studied chemokine CCL7 in a model of unilateral ureteral obstruction (UUO)-induced TIF. We observed that the role of CCL7 differs depending on the stage of the pathology. In early stages (0-8 days), CCL7 deficient (CCL7-KO) mice displayed attenuated TIF potentially involving two mechanisms: an early (0-3 days) decrease of inflammatory cell infiltration followed (3-8 days) by a decrease in tubular ECM production independent of inflammation. In contrast, during later stages of obstruction (10-14 days), CCL7-KO mice displayed increased TIF which was again associated with reduced inflammation. Interestingly, the switch between this anti- to profibrotic effect was accompanied by an increased influx of immunosuppressive regulatory T cells. In conclusion, these results highlight for the first time a dual role for CCL7 in the development of renal TIF, deleterious in early stages but beneficial during later stages. (C) 2013 Elsevier Inc. All rights reserved.

p38 mitogen-activated protein kinase (MAPK) is thought to play a central role in acute and chronic inflammatory responses. Whether p38MAPK plays a pathogenic role in crescentic GN (GN) and which of its four isoforms is preferentially involved in kidney inflammation is not definitely known. We thus examined expression and activation of p38MAPK isoforms during antiglomerular basement membrane (GBM) nephritis. Therefore, p38 alpha conditional knockout mice (MxCre-p38 alpha(Delta/Delta)) were used to examine the role of p38 alpha in anti-GBM induced nephritis. Both wild type and MxCre-p38 alpha(Delta/Delta) mice developed acute renal failure over time. Histological examinations revealed a reduced monocyte influx and less tubular damage in MxCre-p38 alpha(Delta/Delta) mice, whereas glomerular crescent formation and renal fibrosis was similar. Likewise, the levels of pro-and anti-inflammatory cytokines such as TNF, IL-1 and IL-10 were similar, but IL-8 was even up-regulated in MxCre-p38 alpha(Delta/Delta) mice. In contrast, we could detect strong down-regulation of chemotactic cytokines such as CCL-2, -5 and -7, in the kidneys of MxCre-p38 alpha(Delta/Delta) mice. In conclusion, p38 alpha is the primary p38MAPK isoform expressed in anti-GBM nephritis and selectively affects inflammatory cell influx and tubular damage. Full protection from nephritis is however not achieved as renal failure and structural damage still occurs.

Long-term treatment with inhaled corticosteroids (ICS) may potentially lead to adrenal insufficiency in children with asthma. A sufficient adrenal response can be tested using protocols involving salivary cortisol measurements. In this study, we investigated in healthy volunteers whether inhalation of fluticasone propionate, a frequently prescribed ICS, interferes with salivary cortisol measurement (with tandem mass spectrometry as well as an immuno-assay). We found that inhalation of fluticasone propionate immediately before saliva collection does not interfere with the salivary cortisol measurement when measured by mass spectrometry. These results suggest that patients with asthma using ICS can be included in research protocols based on salivary cortisol mass spectrometry measurements.

Anti-neutrophil cytoplasmic autoantibodies (ANCA) with a specificity for myeloperoxidase or proteinase 3 are closely associated with small vessel vasculitides (SVV). In vitro, ANCA activate primed neutrophils to release toxic substances that destroy endothelial cells, suggesting a pathogenic role for these autoantibodies in disease development. However, to study the complex interplay between ANCA, neutrophils, and the local environment in vivo, animal models are required. Here, we will review the animal models developed for ANCA-SVV and discuss how these models have been applied to study ANCA-SVV pathogenesis. In addition, some directions for future research pertaining to unresolved issues relevant for the pathogenesis and immunogenesis of ANCA-SVV are proposed.