Christof J. Majoor

Characterizing responses to CFTR-modulating drugs using rectal organoids derived from subjects with cystic fibrosis

Rectal organoids from subjects with cystic fibrosis can be used to assess responses to drugs that modulate CFTR. Mini-guts for personalized cystic fibrosis therapy Cystic fibrosis is caused by mutations in the CFTR gene that severely reduce the function of the CFTR protein. New drugs for treating cystic fibrosis modulate CFTR protein function, but drug efficacy is dependent on which CFTR mutation a patient carries. Dekkers et al. now show that the efficacy of these drugs can be individually assessed in a laboratory test using epithelial cells cultured as mini-guts from rectal biopsies from subjects with cystic fibrosis. The authors show that the drug responses observed in mini-guts or rectal organoids can be used to predict which patients may be potential responders to the drug. This preclinical test may help to quickly identify responders to CFTR-modulating drug therapy even when patients carry very rare CFTR mutations. Identifying subjects with cystic fibrosis (CF) who may benefit from cystic fibrosis transmembrane conductance regulator (CFTR)–modulating drugs is time-consuming, costly, and especially challenging for individuals with rare uncharacterized CFTR mutations. We studied CFTR function and responses to two drugs—the prototypical CFTR potentiator VX-770 (ivacaftor/KALYDECO) and the CFTR corrector VX-809 (lumacaftor)—in organoid cultures derived from the rectal epithelia of subjects with CF, who expressed a broad range of CFTR mutations. We observed that CFTR residual function and responses to drug therapy depended on both the CFTR mutation and the genetic background of the subjects. In vitro drug responses in rectal organoids positively correlated with published outcome data from clinical trials with VX-809 and VX-770, allowing us to predict from preclinical data the potential for CF patients carrying rare CFTR mutations to respond to drug therapy. We demonstrated proof of principle by selecting two subjects expressing an uncharacterized rare CFTR genotype (G1249R/F508del) who showed clinical responses to treatment with ivacaftor and one subject (F508del/R347P) who showed a limited response to drug therapy both in vitro and in vivo. These data suggest that in vitro measurements of CFTR function in patient-derived rectal organoids may be useful for identifying subjects who would benefit from CFTR-correcting treatment, independent of their CFTR mutation.

Asthma and coagulation

Asthma is a chronic airway disease characterized by paroxysmal airflow obstruction evoked by irritative stimuli on a background of allergic lung inflammation. Currently, there is no cure for asthma, only symptomatic treatment. In recent years, our understanding of the involvement of coagulation and anticoagulant pathways, the fibrinolytic system, and platelets in the pathophysiology of asthma has increased considerably. Asthma is associated with a procoagulant state in the bronchoalveolar space, further aggravated by impaired local activities of the anticoagulant protein C system and fibrinolysis. Protease-activated receptors have been implicated as the molecular link between coagulation and allergic inflammation in asthma. This review summarizes current knowledge of the impact of the disturbed hemostatic balance in the lungs on asthma severity and manifestations and identifies new possible targets for asthma treatment.

Risk of deep vein thrombosis and pulmonary embolism in asthma

Increasing evidence suggests that patients with asthma have activated coagulation within the airways. Whether this leads to an increase in venous thromboembolic events is unknown. We therefore assessed the incidence of venous thromboembolic events in patients with mild-to-moderate and severe asthma as compared with an age- and sex-matched reference population. 648 patients with asthma (283 with severe and 365 patients with mild-to-moderate asthma) visiting three Dutch outpatient asthma clinics were studied. All patients completed a questionnaire about a diagnosis of deep vein thrombosis and pulmonary embolism in the past, their risk factors, history of asthma and medication use. All venous thromboembolic events were objectively verified. In total, 35 venous thromboembolic events (16 deep vein thrombosis and 19 pulmonary embolism) occurred at a median age of 39 (range 20–63) years. The incidence of pulmonary embolism in patients with severe asthma was 0.93 (95% CI 0.42–1.44) per 1000 person-years, 0.33 (95% CI 0.07–0.60) in mild-to-moderate asthma and 0.18 (95% CI 0.03–0.33) in the general population, respectively. Severe asthma and oral corticosteroid use were independent risk factors of pulmonary embolism (hazard ratios 3.33 (1.16–9.93) and 2.82 (1.09–7.30), respectively). Asthma was not associated with deep vein thrombosis. Severe asthma greatly enhances the risk of pulmonary embolism, particularly if chronic corticosteroids are used. Severe asthma greatly enhances the risk of pulmonary embolism, particularly if chronic corticosteroids are used http://ow.ly/moNaO

Exhaled breath profiles in the monitoring of loss of control and clinical recovery in asthma

Asthma is a chronic inflammatory airway disease, associated with episodes of exacerbations. Therapy with inhaled corticosteroids (ICS) targets airway inflammation, which aims to maintain and restore asthma control. Clinical features are only modestly associated with airways inflammation. Therefore, we hypothesized that exhaled volatile metabolites identify longitudinal changes between clinically stable episodes and loss of asthma control.

Activated protein C inhibits neutrophil migration in allergic asthma: a randomised trial

Asthma patients show evidence of a procoagulant state in their airways, accompanied by an impaired function of the anticoagulant protein C system. We aimed to study the effect of recombinant human activated protein C (rhAPC) in allergic asthma patients. We conducted a randomised, double-blind, placebo-controlled, proof-of-concept study in house dust mite (HDM) allergic asthma patients. Patients were randomised to receive intravenous rhAPC (24 µg·kg−1·h−1; n=12) or placebo (n=12) for 11 h. 4 h after the start of infusion, a first bronchoscopy was performed to challenge one lung segment with saline (control) and a contralateral segment with a combination of HDM extract and lipopolysaccharide (HDM+LPS), thereby mimicking environmental house dust exposure. A second bronchoscopy was conducted 8 h after intrabronchial challenge to obtain bronchoalveolar lavage fluid (BALF). rhAPC did not influence HDM+LPS induced procoagulant changes in the lung. In contrast, rhAPC reduced BALF leukocyte counts by 43% relative to placebo, caused by an inhibitory effect on neutrophil influx (64% reduction), while leaving eosinophil influx unaltered. rhAPC also reduced neutrophil degranulation products in the airways. Intravenous rhAPC attenuates HDM+LPS-induced neutrophil migration and protein release in allergic asthma patients by an effect that does not rely on coagulation inhibition. Recombinant activated protein C attenuates allergen-induced migration of neutrophils to the bronchoalveolar space of asthma patients http://ow.ly/Rsevw

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.

The influence of corticosteroids on hemostasis in healthy subjects

Essentials Corticosteroids are associated with venous thromboembolism in patients with inflammatory diseases. Healthy subjects received 0.5 mg kg−1 of prednisolone or placebo for 10 days in a randomized study. von Willebrand factor, plasminogen activator type 1 and in vitro thrombin generation were enhanced. Corticosteroids may contribute to the thromboembolic risk in patients with inflammatory diseases.

β2-Adrenergic receptor agonists activate CFTR in intestinal organoids and subjects with cystic fibrosis

We hypothesized that people with cystic fibrosis (CF) who express CFTR (cystic fibrosis transmembrane conductance regulator) gene mutations associated with residual function may benefit from G-protein coupled receptor (GPCR)-targeting drugs that can activate and enhance CFTR function. We used intestinal organoids to screen a GPCR-modulating compound library and identified β2-adrenergic receptor agonists as the most potent inducers of CFTR function. β2-Agonist-induced organoid swelling correlated with the CFTR genotype, and could be induced in homozygous CFTR-F508del organoids and highly differentiated primary CF airway epithelial cells after rescue of CFTR trafficking by small molecules. The in vivo response to treatment with an oral or inhaled β2-agonist (salbutamol) in CF patients with residual CFTR function was evaluated in a pilot study. 10 subjects with a R117H or A455E mutation were included and showed changes in the nasal potential difference measurement after treatment with oral salbutamol, including a significant improvement of the baseline potential difference of the nasal mucosa (+6.35 mV, p<0.05), suggesting that this treatment might be effective in vivo. Furthermore, plasma that was collected after oral salbutamol treatment induced CFTR activation when administered ex vivo to organoids. This proof-of-concept study suggests that organoids can be used to identify drugs that activate CFTR function in vivo and to select route of administration. β2-Adrenergic receptor agonists as CFTR activating drugs in subjects with CFTR residual function http://ow.ly/Dm44300wjuw

Loss of asthma control and activation of coagulation and fibrinolysis

Epidemiologic studies have shown that patients with severe asthma have increased risk of pulmonary embolism, in particular patients with frequent asthma exacerbations. Therefore, we hypothesized that asthma exacerbations are associated with increased haemostatic activity.

Allergic burden and the risk of venous thromboembolism

Asthma affects around 300 million people around the world. Some patients present episodes in which symptoms are worsened, resulting in an exacerbation. Although its etiology is still unknown, some viral agents are possible triggers, but their role is still unclear. We determined the prevalence of 5 viruses in a population of children with exacerbations and a possible association between their presence and their age, the severity of the crisis, medication used, admission to ICU and hospitalization, as well as a possible relationship between these variables and HRV’s subtypes as well as RSV’s load. Nasopharyngeal aspirates of pediatric patients with a previous diagnosis of asthma, admitted to two health institutions, were analyzed to detect hAdV, HBoV, HRV, EV and RSV. PCR, RT-PCR and qPCR were performed for each case followed by subsequent sequencing. 175 patients were included in this study, in which HRV was the most frequently detected agent. Despite its high prevalence, we found no association between its detection or group type and the analyzed variables, as well as for the other viruses analyzed. Regarding RSV, the data suggested a significant relationship between RSV load and gender, being this, the first report to find this possible association. These results reinforce the importance of HRV in exacerbations in pediatric patients, especially regarding type C, but their presence apparently does not correlate with the severity or any demographic or clinical variable, as well as for the other viruses analyzed. On the other hand, we found a possible significant relationship between RSV load and gender but more studies are required to determine the relation between these variables.