Prothrombotic state in patients with severe and prednisolone-dependent asthma.

BACKGROUND: Epidemiologic studies have shown that asthmatic patients, in particular those with severe disease, have increased risk of pulmonary embolism. It is unknown whether these patients have a prothrombotic state under stable conditions. OBJECTIVE: We sought to compare coagulation and fibrinolysis parameters between healthy subjects and patients with mild, severe, and prednisolone-dependent asthma under stable conditions and to investigate whether hemostatic markers correlate with airway inflammation. METHODS: In 126 adults (33 healthy control subjects, 31 patients with mild asthma, 32 patients with severe asthma, and 30 patients with prednisolone-dependent asthma) parameters of inflammation (peripheral blood eosinophils and neutrophils) and markers of hemostasis (endogenous thrombin potential [ETP], thrombin-antithrombin complex, plasmin-α2-antiplasmin complex, plasminogen activator inhibitor type 1 [PAI-1], D-dimer, and von Willebrand factor [vWF]) were measured in plasma. One-way ANOVA with the post hoc Bonferroni test was used for group comparison, and linear regression analysis was used for correlations. RESULTS: We observed increased ETP (121% vs 99%, overall P < .01), plasmin-α2-antiplasmin complex (520 vs 409 µg/L, overall P = .04), PAI-1 (10 vs 7 ng/mL, overall P = .02), and vWF (142% vs 87%, overall P < .01) levels in asthmatic patients compared with healthy control subjects. ETP, PAI-1, and vWF levels increased with increasing asthma severity. In addition, we found a correlation between ETP and vWF with neutrophil but not eosinophil counts. CONCLUSION: Asthmatic patients have a prothrombotic state that increases with asthma severity. This might explain why patients with asthma, in particular those with severe disease, have an increased risk of venous thromboembolism.

Oral and inhaled corticosteroid use and risk of recurrent pulmonary embolism.

INTRODUCTION: Chronic inflammatory diseases predispose for development of a first pulmonary embolism (PE). Previous studies showed that corticosteroids, which are the mainstay of treatment for inflammatory diseases, enhance the risk of a first venous thromboembolism. Yet, it is unknown whether corticosteroids also predispose for recurrent events. Therefore, we investigated the association between oral and/or inhaled corticosteroid use and the risk of recurrent PE. METHODS: We performed a nested case-control study using the PHARMO Database. Adult patients who had suffered from a first PE for which vitamin K antagonists were prescribed, were eligible. Of these, 384 patients with recurrent PE were matched to 1030 patients without recurrent PE. RESULTS: We showed that oral or inhaled corticosteroids was ever used by 22.7% and 20.6% of patients with recurrent PE, and 23.5% and 21.5% of the patients without recurrent PE. There was an overall association between oral corticosteroid use and the risk of recurrent PE (p=0.02). Current use of oral corticosteroids increased the risk of recurrent PE (OR 3.74; 95% CI 2.04-6.87), whereas past use reduced the risk (OR 0.46; 95% CI 0.28-0.74). A similar pattern was observed for inhaled corticosteroids, although less strong (p=0.10). CONCLUSIONS: Current use of oral corticosteroids is associated with increased risk of recurrent PE. Whether this increased risk is caused by oral corticosteroids themselves, or by the underlying disease, or both, needs further investigation. Nevertheless, given the frequent use of corticosteroids in clinical practice, clinicians should be aware of this risk.

Lymph node stromal cells constrain immunity via MHC class II self-antigen presentation.

Non-hematopoietic lymph node stromal cells shape immunity by inducing MHC-I-dependent deletion of self-reactive CD8+ T cells and MHC-II-dependent anergy of CD4+ T cells. In this study, we show that MHC-II expression on lymph node stromal cells is additionally required for homeostatic maintenance of regulatory T cells (Tregs) and maintenance of immune quiescence. In the absence of MHC-II expression in lymph node transplants, i.e. on lymph node stromal cells, CD4+ as well as CD8+ T cells became activated, ultimately resulting in transplant rejection. MHC-II self-antigen presentation by lymph node stromal cells allowed the non-proliferative maintenance of antigen-specific Tregs and constrained antigen-specific immunity. Altogether, our results reveal a novel mechanism by which lymph node stromal cells regulate peripheral immunity.