Anti-IL-5 in Mild Asthma Alters Rhinovirus-induced Macrophage, B-Cell, and Neutrophil Responses (MATERIAL). A Placebo-controlled, Double-Blind Study.

RATIONALE: Eosinophils drive pathophysiology in stable and exacerbating eosinophilic asthma, and therefore treatment is focused on the reduction of eosinophil numbers. Mepolizumab, a humanized monoclonal antibody that neutralizes IL-5 and efficiently attenuates eosinophils, proved clinically effective in severe eosinophilic asthma but not in mild asthma. OBJECTIVES: To study the effect of mepolizumab on virus-induced immune responses in mild asthma. METHODS: Patients with mild asthma, steroid-naive and randomized for eosinophil numbers, received 750 mg mepolizumab intravenously in a placebo-controlled double-blind trial, 2 weeks after which patients were challenged with rhinovirus (RV) 16. FEV1, FVC, fractional exhaled nitric oxide, symptom scores (asthma control score), viral load (PCR), eosinophil numbers, humoral (luminex, ELISA), and cellular (flow cytometry) immune parameters in blood, BAL fluid, and sputum, before and after mepolizumab and RV16, were assessed. MEASUREMENTS AND MAIN RESULTS: Mepolizumab attenuated baseline blood eosinophils and their activation, attenuated trendwise sputum eosinophils, and enhanced circulating natural killer cells. Mepolizumab did not affect FEV1, FVC, and fractional exhaled nitric oxide, neither at baseline nor after RV16. On RV16 challenge mepolizumab did not prevent eosinophil activation but did enhance local B lymphocytes and macrophages and reduce neutrophils and their activation. Mepolizumab also enhanced secretory IgA and reduced tryptase in BAL fluid. Finally, mepolizumab affected particularly RV16-induced macrophage inflammatory protein-3a, vascular endothelial growth factor-A, and IL-1RA production in BAL fluid. CONCLUSIONS: Mepolizumab failed to prevent activation of remaining eosinophils and changed RV16-induced immune responses in mild asthma. Although these latter effects likely are caused by attenuated eosinophil numbers, we cannot exclude a role for basophils. Clinical trial registered with www.clinicaltrials.gov (NCT 01520051).

A short course of infusion of a hydrogen sulfide-donor attenuates endotoxemia induced organ injury via stimulation of anti-inflammatory pathways, with no additional protection from prolonged infusion.

Organ failure is associated with increased mortality and morbidity in patients with systemic inflammatory response syndrome. Previously, we showed that a short course of infusion of a hydrogen sulfide (H(2)S) donor reduced metabolism with concurrent reduction of lung injury. Here, we hypothesize that prolonged H(2)S infusion is more protective than a short course in endotoxemia with organ failure. Also, as H(2)S has both pro- and anti-inflammatory effects, we explored the effect of H(2)S on interleukin production. Endotoxemia was induced by an intravenous bolus injection of LPS (7.5mg/kg) in mechanically ventilated rats. H(2)S donor NaHS (2mg/kg) or vehicle (saline) was infused and organ injury was determined after either 4 or 8h. A short course of H(2)S infusion was associated with reduction of lung and kidney injury. Prolonged infusion did not enhance protection. Systemically, infusion of H(2)S increased both the pro-inflammatory response during endotoxemia, as demonstrated by increased TNF-α levels, as well as the anti-inflammatory response, as demonstrated by increased IL-10 levels. In LPS-stimulated whole blood of healthy volunteers, co-incubation with H(2)S had solely anti-inflammatory effects, resulting in decreased TNF-α levels and increased IL-10 levels. Co-incubation with a neutralizing IL-10 antibody partly abrogated the decrease in TNF-α levels. In conclusion, a short course of H(2)S infusion reduced organ injury during endotoxemia, at least in part via upregulation of IL-10.

Increased pro-inflammatory cytokine production in Down Syndrome children upon stimulation with live influenza A virus.

PURPOSE: Children with down syndrome (DS) have an increased susceptibility to infections, due to altered humoral and/or cellular immunity. The aim of this study was to determine the cytokine production in whole blood of children with DS upon stimulation with live influenza A virus. METHODS: Whole blood of 61 children with DS and 57 of their healthy siblings was stimulated with 2.5 × 10(4) TCID50/ml influenza A virus during 6, 24, and 48 h. TNF-α, IL-1ß, IL-6, IL-8, IL-10, IL-12p70, IFN-α, IFN-γ concentrations, and viral load were measured at all time points. RESULTS: At most of the time points, TNF-α, IL-1ß, IL-6, and IL-8 concentrations were significantly higher in children with DS following stimulation with live influenza A virus. IFN-α and IFN-γ levels were also significantly higher in the DS group. Viral clearance, however, was equal in both groups. CONCLUSIONS: Children with DS have an altered immune response to influenza A virus. The production of higher levels of pro-inflammatory cytokines may be responsible for a more severe clinical course of viral disease in these children.

Effects on coagulation and fibrinolysis induced by influenza in mice with a reduced capacity to generate activated protein C and a deficiency in plasminogen activator inhibitor type 1.

Influenza infections increase the risk of diseases associated with a prothrombotic state, such as venous thrombosis and atherothrombotic diseases. However, it is unclear whether influenza leads to a prothrombotic state in vivo. To determine whether influenza activates coagulation, we measured coagulation and fibrinolysis in influenza-infected C57BL/6 mice. We found that influenza increased thrombin generation, fibrin deposition, and fibrinolysis. In addition, we used various anti- and prothrombotic models to study pathways involved in the influenza-induced prothrombotic state. A reduced capacity to generate activated protein C in TM(pro/pro) mice increased thrombin generation and fibrinolysis, whereas treatment with heparin decreased thrombin generation in influenza-infected C57Bl/6 mice. Thrombin generation was not changed in hyperfibrinolytic mice, deficient in plasminogen activator inhibitor type-1 (PAI-1(-/-)); however, increased fibrin degradation was seen. Treatment with tranexamic acid reduced fibrinolysis, but thrombin generation was unchanged. We conclude that influenza infection generates thrombin, increased by reduced levels of protein C and decreased by heparin. The fibrinolytic system appears not to be important for thrombin generation. These findings suggest that influenza leads to a prothrombotic state by coagulation activation. Heparin treatment reduces the influenza induced prothrombotic state.

Noncanonical NF-kappaB signaling in dendritic cells is required for indoleamine 2,3-dioxygenase (IDO) induction and immune regulation.

Ligation of CD40 on dendritic cells (DCs) induces early production of inflammatory mediators via canonical NF-kappaB signaling, as well as late expression of the anti-inflammatory enzyme indoleamine 2,3-dioxygenase (IDO) via unknown signal transduction. By selective blocking of either the canonical NF-kappaB pathway using the NEMO-binding domain peptide or the noncanonical NF-kappaB pathway by small interfering RNA, we demonstrate that IDO expression requires noncanonical NF-kappaB signaling. Also, noncanonical NF-kappaB signaling down-regulates proinflammatory cytokine production in DCs. In addition, selective activation of the noncanonical NF-kappaB pathway results in noninflammatory DCs that suppress T-cell activation and promote the development of T cells with regulatory properties. These findings reveal an important role of the noncanonical NF-kappaB pathway in the regulation of immunity.