Background
Interleukin (IL) 37 has been described as a negative regulator of innate immunity, as it reduces the activation and cytokine production of different innate immune cells. Recently, results ...from the CLARA childhood asthma cohort suggested an implication of IL‐37 for human asthma pathogenesis. This study aimed to investigate the effects of IL‐37 on allergic airway inflammation in a mouse model of experimental asthma.
Methods
Peripheral blood mononuclear cells (PBMCs) of children were cultured for 48 h (anti‐CD3/anti‐CD28 stimulation or unstimulated), and IL‐37 concentrations in supernatants were determined. Wild‐type, IL‐18Rα‐deficient (−/−), and SIGIRR−/− C57BL/6 mice were sensitized to ovalbumin (OVA) and challenged with OVA aerosol to induce acute experimental asthma, and IL‐37 was applied intranasally prior to each OVA challenge. Airway hyper‐responsiveness (AHR), airway inflammation, cytokine levels in broncho‐alveolar lavage fluid, and mucus production were determined.
Results
IL‐37 production of human PBMCs was significantly lower in allergic asthmatics vs healthy children. In wild‐type mice, intranasal administration of IL‐37 ablated allergic airway inflammation as well as cytokine production and subsequently diminished the hallmarks of experimental asthma including mucus hyperproduction and AHR. In contrast, local application of IL‐37 produced none of these effects in mice lacking either IL18Rα or SIGIRR/IL‐1R8.
Conclusions
This study demonstrates that IL‐37 is able to ablate a TH2 cell‐directed allergic inflammatory response and the hallmarks of experimental asthma in mice, suggesting that IL‐37 may be critical for asthma pathogenesis. Furthermore, these data suggest a mode of action of IL‐37 that involves IL18Rα as well as the orphan receptor SIGIRR/IL‐1R8.
Summary
Various complement‐mediated renal disorders are treated currently with the complement inhibitor eculizumab. By blocking the cleavage of C5, this monoclonal antibody prevents cell damage ...caused by complement‐mediated inflammation. We included 23 patients with atypical haemolytic uraemic syndrome (aHUS, n = 12), C3 glomerulopathies (C3G, n = 9) and acute antibody‐mediated renal graft rejection (AMR, n = 2), treated with eculizumab in 12 hospitals in Germany. We explored the course of complement activation biomarkers and the benefit of therapeutic drug monitoring of eculizumab. Complement activation was assessed by analysing the haemolytic complement function of the classical (CH50) and the alternative pathway (APH50), C3 and the activation products C3d, C5a and sC5b‐9 prior to, 3 and 6 months after eculizumab treatment. Eculizumab concentrations were determined by a newly established specific enzyme‐linked immunosorbent assay (ELISA). Serum eculizumab concentrations up to 1082 μg/ml point to drug accumulation, especially in paediatric patients. Loss of the therapeutic antibody via urine with concentrations up to 56 μg/ml correlated with proteinuria. In aHUS patients, effective complement inhibition was demonstrated by significant reductions of CH50, APH50, C3d and sC5b‐9 levels, whereas C5a levels were only reduced significantly after 6 months' treatment. C3G patients presented increased C3d and consistently low C3 levels, reflecting ongoing complement activation and consumption at the C3 level, despite eculizumab treatment. A comprehensive complement analysis together with drug monitoring is required to distinguish mode of complement activation and efficacy of eculizumab treatment in distinct renal disorders. Accumulation of the anti‐C5 antibody points to the need for a patient‐orientated tailored therapy.
Analysis of complement activation biomarkers prior to, 3 and 6 months after eculizumab treatment in 23 patients treated with eculizumab for atypical hemolytic uremic syndrome (aHUS, n=12), C3 glomerulopathies (C3G, n=9) or acute antibody‐mediated renal graft rejection (AMR, n=2) indicate effective inhibition in aHUS and AMR patients, whereas increased C3d and consistently low C3 levels reflect ongoing complement activation in C3G patients. Therapeutic drug monitoring, performed by a newly established specific ELISA, revealed serum eculizumab concentrations up to 1082 μg/mL pointing to drug accumulation especially in pediatric patients, which indicates the need of a patient‐oriented tailored therapy.
Regeneration of the gas exchange area by induction of neoalveolarisation would greatly improve therapeutic options in destructive pulmonary diseases. Unilateral pneumonectomy is an established model ...to remove defined portions of gas exchange area and study mechanisms of compensatory lung growth. The question of whether new alveoli are added to the residual lung after pneumonectomy in mice was addressed. Left-sided pneumonectomy was performed in 11 adult C57BL/6 mice. Alveolar numbers were analysed in lungs fixed at days 6 and 20 after pneumonectomy and in 10 age-matched controls using design-based stereology based on a physical fractionator. Post-fixation lung volume was determined by fluid displacement. Complete restoration of lung volume was observed 20 days after pneumonectomy. Alveolar numbers were significantly increased by 33% in residual right lungs at day 20 in comparison with control right lungs. In control left lungs, an average of 471+/-162 x 10(3) alveoli was estimated, 49% of which were regenerated by residual lungs at day 20. Of the newly formed alveoli seen at day 20, 74% were already present at day 6. The present data demonstrate that, in addition to growth in size of existing alveoli, neoalveolarisation contributes to restoration of the gas exchange area in adult mice and is induced early after pneumonectomy.
In order to investigate the hypothesis that the mammalian target of rapamycin inhibitor everolimus (EVR) shows anticytomegalovirus (CMV) activity in pediatric patients, we analyzed the impact of ...EVR‐based immunosuppressive therapy on CMV replication and disease in a large cohort (n = 301) of pediatric kidney allograft recipients. The EVR cohort (n = 59), who also received low‐dose cyclosporin, was compared with a control cohort (n = 242), who was administered standard‐dose cyclosporin or tacrolimus and an antimetabolite, mostly mycophenolate mofetil (91.7%). Multivariate analysis revealed an 83% lower risk of CMV replication in the EVR cohort than in the control cohort (p = 0.005). In CMV high‐risk (donor+/recipient−) patients (n = 88), the EVR‐based regimen was associated with a significantly lower rate of CMV disease (0% vs. 14.3%, p = 0.046) than the standard regimen. In patients who had received chemoprophylaxis with (val‐)ganciclovir (n = 63), the CMV‐free survival rates at 1 year and 3 years posttransplant (100%) were significantly (p = 0.015) higher in the EVR cohort (n = 15) than in the control cohort (n = 48; 1 year, 75.0%; 3 years, 63.3%). Our data suggest that in pediatric patients at high risk of CMV, an EVR‐based immunosuppressive regimen is associated with a lower risk of CMV disease than a standard‐dose calcineurin inhibitor–based regimen.
This study in 301 pediatric kidney transplant recipients of the Cooperative European Paediatric Renal Transplant Initiative Registry associates the use of everolimus and low‐dose cyclosporine with a lower incidence of cytomegalovirus infection compared to a standard‐dose calcineurin inhibitor‐based regimen in patients at high risk of cytomegalovirus infection.
Summary
Background
Bronchial asthma is characterized by chronic airway inflammation and airway remodelling which occurs in both proximal and distal airways. These changes are associated with ...development of airway hyper‐responsiveness and airflow limitation.
Objective
This study was aimed to analyse whether chronic inhalative allergen challenges in mice lead to morphological and physiological changes comparable with this phenotype.
Methods
For this purpose, BALB/c mice were systemically sensitized to ovalbumin (OVA) followed by aerosol allergen challenges on 2 consecutive days per week for 12 weeks.
Results
In chronically challenged mice, tissue inflammation in proximal as well as distal airways was observed with a predominance of lymphocytes within the cellular infiltrate. In contrast, inflammation in the airway lumen decreased over time. These changes were associated by a shift in bronchoalveolar lavage–cytokine levels from IL‐4, IL‐5 and TNF‐α production (during the acute phase) towards markedly increased levels of TGF‐β during the chronic phase. Goblet cell hyperplasia and subepithelial fibrosis occurred throughout the airway tree. In terms of lung function, chronically challenged mice developed persistent bronchial hyper‐responsiveness and progressive airflow limitation. Six weeks after OVA aerosol discontinuation, airway inflammation still persisted although lung function was normalized.
Conclusion
These data indicate that our model of chronic aerosol allergen challenges leads to a phenotype of experimental asthma with participation of distal airways and persistence of inflammation thereby resembling many morphological and physiological aspects of human bronchial asthma.
Summary
Background
Non‐selective cation influx through canonical transient receptor potential channels (TRPCs) is thought to be an important event leading to airway inflammation. TRPC6 is highly ...expressed in the lung, but its role in allergic processes is still poorly understood.
Objective
The purpose of this study was to evaluate the role of TRPC6 in airway hyperresponsiveness (AHR) and allergic inflammation of the lung.
Methods
Methacholine‐induced AHR was assessed by head‐out body plethysmography of wild type (WT) and TRPC6−/− mice. Experimental airway inflammation was induced by intraperitoneal ovalbumin (OVA) sensitization, followed by OVA aerosol challenges. Allergic inflammation and mucus production were analysed 24 h after the last allergen challenge.
Results
Methacholine‐induced AHR and agonist‐induced contractility of tracheal rings were increased in TRPC6−/− mice compared with WT mice, most probably due to compensatory up‐regulation of TRPC3 in airway smooth muscle cells. Most interestingly, when compared with WT mice, TRPC6−/− mice exhibited reduced allergic responses after allergen challenge as evidenced by a decrease in airway eosinophilia and blood IgE levels, as well as decreased levels of T‐helper type 2 (Th2) cytokines (IL‐5, IL‐13) in the bronchoalveolar lavage. However, lung mucus production after allergen challenge was not altered by TRPC6 deficiency.
Conclusions
TRPC6 deficiency inhibits specific allergic immune responses, pointing to an important immunological function of this cation channel in Th2 cells, eosinophils, mast cells and B cells.
CORRESPONDENCE: Dept of Internal Medicine (Respiratory Medicine), Philipps-University of Marburg, Baldingerstrasse, D-35043 Marburg, Germany. Fax: 49 64212864936. E-mail: ...heinz.fehrenbach{at}staff.uni-marburg.de
A variety of animal models have been suggested as models of pulmonary emphysema; these are critically discussed in the present article from a stereologist's perspective. In addition, a stereological design for the quantification of experimentally induced emphysema is proposed.
On the basis of the widely accepted definition of pulmonary emphysema being an "abnormal permanent enlargement of the airspaces distal to the terminal bronchioles, accompanied by destruction of their walls," quantitative morphology is the only method with which to reliably assess the presence of emphysema. Recognising this, careful inspection of animal models that are based on instillation of elastase, genetic alterations, inhalation of cigarette smoke or induction of apoptosis, reveals that both criteria of emphysema definition were demonstrated in surprisingly few of them.
Several aspects are suggested to be critical for the understanding of animal models of human emphysema. For example, genetic models that rely on the inhibition of the formation of alveoli during post-natal alveolarisation should clearly be distinguished from models that rely on the loss of mature alveoli after alveolarisation is complete. Furthermore, inhalation models that are characterised by exposed animals exhibiting a severe loss of body weight should carefully examine the relative contribution of intervention and weight loss, respectively. Models that rely on the exposure of juvenile animals for several weeks or even months should take into account the effects of normal lung growth and ageing.
Stereology offers appropriate tools with which to quantify the parameters relevant to assess development and the regeneration of emphysema. Stereologists continue to develop tools that will help ascertain the reliability of established and new models. If inappropriate parameters continue to be used for the evaluation of animal models of emphysema, thinking and resources are likely to be misdirected and the models may limit rather than expand the understanding of human emphysema and the development of new therapies.
KEYWORDS: Animal model, chronic obstructive pulmonary disease, emphysema, quantitative morphology, stereology
A model of inducible expansion of the gas exchange area in adult mice would be ideal for the investigation of molecular determinants of airspace regeneration in vivo. Therefore, the ...post-pneumonectomy (post-PNX) compensatory lung growth in adult C57BL/6 mice was characterised in this study. Mice underwent left-sided PNX. Right lung volume was assessed on days 1, 3, 5, 7, 10 and 21 after PNX, and total DNA and cellular proliferation of the right lung were determined. Lung histology was studied using immunohistochemistry and quantitatively characterised by detailed stereological investigations. Pulmonary function was assessed using a mouse body-plethysmograph. Following PNX, right-lung volume rapidly restored the initial volume of left and right lung. Total DNA increased significantly over 21 days and equalled the total DNA amount of both lungs in the control mice. Septal cell proliferation significantly increased after PNX, and included endothelial cells, epithelial cells, smooth muscle cells and fibroblasts. Stereological investigations of left and right control lungs versus right lungs 21 days after PNX indicated complete restoration of body mass-specific alveolar surface area. Pulmonary function testing showed marked alteration at 3 days and normalisation at 21 days post-PNX. In conclusion, well reproducible reconstitution of alveolar gas-exchange surface based on septal tissue expansion may be provoked by pneumonectomy in adult mice.
Summary
Background
Increased mucus production is a critical factor impairing lung function in patients suffering from bronchial asthma, the most common chronic inflammatory lung disease worldwide.
...Objective
This study aimed at investigating whether goblet cell (GC) metaplasia and mucus production are differentially regulated in proximal and distal airways.
Methods
Female Balb/c mice were sensitized to ovalbumin (OVA) and challenged with an OVA‐aerosol on two consecutive days for 1 week (acute) or 12 weeks (chronic). Real‐time RT‐PCR analysis was applied on microdissected airways.
Results
In acutely and chronically OVA‐challenged mice, GC metaplasia and mucus production were observed in proximal but not in distal airways. In contrast, inflammation reflected by the infiltration of eosinophils and expression of the TH2‐type cytokines IL‐4 and IL‐13 was increased in both proximal and distal airways. Abundance of IL‐13Rα1 was lower in distal airways of healthy control mice. Under acute and chronic OVA‐exposure, activation of IL‐13Rα1‐dependent signalling cascade, reflected by Spdef and Foxo3A transcription factors, was attenuated in distal compared to proximal airways.
Conclusion and Clinical Relevance
These data indicate that distal airways might be less sensitive to IL‐13‐induced GC metaplasia and mucus production through lower expression of IL‐13Rα1 and attenuated activation of downstream signalling. This might represent a protective strategy to prevent mucus plugging of distal airways and thus impaired ventilation of attached alveoli.
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