Histologic Findings of Severe/Therapy-Resistant Asthma From Video-assisted Thoracoscopic Surgery Biopsies

Epithelial-Mesenchymal Transition Mechanisms in Chronic Airway Diseases: A Common Process to Target?

Epithelial-to-mesenchymal transition (EMT) is a reversible process, in which epithelial cells lose their epithelial traits and acquire a mesenchymal phenotype. This transformation has been described in different lung diseases, such as lung cancer, interstitial lung diseases, asthma, chronic obstructive pulmonary disease and other muco-obstructive lung diseases, such as cystic fibrosis and non-cystic fibrosis bronchiectasis. The exaggerated chronic inflammation typical of these pulmonary diseases can induce molecular reprogramming with subsequent self-sustaining aberrant and excessive profibrotic tissue repair. Over time this process leads to structural changes with progressive organ dysfunction and lung function impairment. Although having common signalling pathways, specific triggers and regulation mechanisms might be present in each disease. This review aims to describe the various mechanisms associated with fibrotic changes and airway remodelling involved in chronic airway diseases. Having better knowledge of the mechanisms underlying the EMT process may help us to identify specific targets and thus lead to the development of novel therapeutic strategies to prevent or limit the onset of irreversible structural changes.

The association between MUC5AC and MUC5B genes expression and remodeling progression in severe neutrophilic asthma: A direct relationship

BACKGROUND

MUC5 dysregulation is a hallmark of severe neutrophilic asthmatic patients. This study investigates the expression of MUC5AC and MUC5B at mRNA levels on asthma severity and airway wall thickness in severe neutrophilic asthmatic patients.

METHOD

In this case-control clinical trial, twenty-five severe neutrophilic asthmatic patients and ten control subjects were enrolled. Subjects underwent ACT, pulmonary functions tests, and fractional exhaled nitric oxide (FENO). Also, induced sputum has been obtained to assess the expression of MUC5AC and MUC5B by the real-time PCR. In addition, the thickness of the airway wall was assessed by high-resolution computed tomography (HRCT), and bioinformatic analysis was implemented to approve the selection of the appropriate genes and for further investigations.

RESULT

A significant difference was observed between the asthmatic and control in MUC5AC and MUC5B mRNA expression. Meanwhile, the expression of MUC5AC increased remarkably by asthma severity; also, it is associated with airway wall thickness (WT) (both P-value <0.05). The expression of MUC5B in asthmatic patients was lower than in control. There is no significant correlation between MUC5B mRNA level and WT and asthma severity. Notably, MUC5AC transcription level was correlated to sputum neutrophil percentage, while MUC5B transcription level had a positive correlation with sputum macrophages and a negative one with sputum neutrophils.

CONCLUSION

In severe neutrophilic asthma, airway wall thickness increases with MUC5AC mRNA overexpression, which is probably related to asthma severity and the formation of mucus plugs. However, the expression of MUC5B was decreased, resulting in poor mucociliary clearance in the airways.

TRIAL REGISTRATION

IR.IAU.MSHD.REC.1400.124.

Anatomical and histopathological approaches to asthma phenotyping

Asthma is typically characterized by variable respiratory symptoms and airflow limitation. Along with the pathophysiology and symptoms are immunological and inflammatory processes. The last decades research has revealed that the immunology of asthma is highly heterogeneous. This has clinical consequences and identification of immunological phenotypes is currently used to guide biological treatment. The focus of this review is on another dimension of asthma diversity, namely anatomical heterogeneity. Immunopathological alterations may go beyond the central airways to also involve the distal airways, the alveolar parenchyma, and pulmonary vessels. Also, extrapulmonary tissues are affected. The anatomical distribution of inflammation in asthma has remained relatively poorly discussed despite its potential implication on both clinical presentation and response to treatment. There is today evidence that a significant proportion of the asthma patients has small airway disease with type 2 immunity, eosinophilia and smooth muscle infiltration of mast cells. The small airways in asthma are also subjected to remodelling, constriction, and luminal plugging, events that are likely to contribute to the elevated distal airway resistance seen in some patients. In cases when the inflammation extends into the alveolar parenchyma alveolar FCER1-high mast cells, eosinophilia, type 2 immunity and activated alveolar macrophages, together with modest interstitial remodelling, create a complex immunopathological picture. Importantly, the distal lung inflammation in asthma can be pharmacologically targeted by use of inhalers with more distal drug deposition. Biological treatments, which are readily distributed to the distal lung, may also be beneficial in eligible patients with more severe and anatomically widespread disease.

Airway remodeling heterogeneity in asthma and its relationship to disease outcomes

Asthma affects an estimated 262 million people worldwide and caused over 461,000 deaths in 2019. The disease is characterized by chronic airway inflammation, reversible bronchoconstriction, and airway remodeling. Longitudinal studies have shown that current treatments for asthma (inhaled bronchodilators and corticosteroids) can reduce the frequency of exacerbations, but do not modify disease outcomes over time. Further, longitudinal studies in children to adulthood have shown that these treatments do not improve asthma severity or fixed airflow obstruction over time. In asthma, fixed airflow obstruction is caused by remodeling of the airway wall, but such airway remodeling also significantly contributes to airway closure during bronchoconstriction in acute asthmatic episodes. The goal of the current review is to understand what is known about the heterogeneity of airway remodeling in asthma and how this contributes to the disease process. We provide an overview of the existing knowledge on airway remodeling features observed in asthma, including loss of epithelial integrity, mucous cell metaplasia, extracellular matrix remodeling in both the airways and vessels, angiogenesis, and increased smooth muscle mass. While such studies have provided extensive knowledge on different aspects of airway remodeling, they have relied on biopsy sampling or pathological assessment of lungs from fatal asthma patients, which have limitations for understanding airway heterogeneity and the entire asthma syndrome. To further understand the heterogeneity of airway remodeling in asthma, we highlight the potential of in vivo imaging tools such as computed tomography and magnetic resonance imaging. Such volumetric imaging tools provide the opportunity to assess the heterogeneity of airway remodeling within the whole lung and have led to the novel identification of heterogenous gas trapping and mucus plugging as important predictors of patient outcomes. Lastly, we summarize the current knowledge of modification of airway remodeling with available asthma therapeutics to highlight the need for future studies that use in vivo imaging tools to assess airway remodeling outcomes.

Structure and function of small airways in asthma patients revisited

Small airways (<2 mm in diameter) are probably involved across almost all asthma severities and they show proportionally more structural and functional abnormalities with increasing asthma severity. The structural and functional alterations of the epithelium, extracellular matrix and airway smooth muscle in small airways of people with asthma have been described over many years using in vitro studies, animal models or imaging and modelling methods. The purpose of this review was to provide an overview of these observations and to outline several potential pathophysiological mechanisms regarding the role of small airways in asthma.

Ultrasound-Guided Transthoracic Mediastinal Biopsy: A Safe Technique for Tissue Diagnosis in Middle- and Low-Income Countries

Background and objectives

The high cost of video-assisted transthoracic procedures precludes their use in the diagnostics of mediastinal masses in low- and middle-income countries (LMICs). This study aims to assess the technical success rate and diagnostic yield of ultrasound-guided transthoracic mediastinal biopsies at a tertiary care hospital.

Methods

This descriptive cross-sectional study was conducted in patients presenting with mediastinal masses referred to radiology services at Dr. Ziauddin University Hospital. Karachi, Pakistan. Ultrasonography was performed using Toshiba Xario 200 & Aplio 500 using convex and linear probes accordingly. Biopsy was performed using a combination of 18G semiautomatic trucut and 17G co-axial needles. Complications and overall diagnostic yields were determined.

Results

In all 70 patients referred, the procedure was completed successfully with an overall procedural yield of 95.7%. Inconclusive biopsies due to inadequate specimen were seen in two (4.2%) patients. No post-procedure major complication or mortality was observed. Minor complications were seen in three (4.2%) out of 70, including hematoma (<3 cm) in one patient and small pneumomediastinum in two patients.

Conclusion

Ultrasound-guided transthoracic mediastinal biopsy may be the pragmatic technique of choice in LMICs for the diagnosis of mediastinal masses as they provide real-time visualization and is cost-effective and safe.

Unravelling the complexity of tissue inflammation in uncontrolled and severe asthma

PURPOSE OF REVIEW

The clinical and inflammatory heterogeneity in asthma constitutes a major challenge for improved treatment. This review describes the nature of the inflammatory complexity and how it can be decoded to yield improved disease understanding and personalized treatment. The focus is on the difficult task of revealing the immunological complexity as it occurs inside diseased patient tissues.

RECENT FINDINGS

The inflammatory heterogeneity in asthma stretches beyond the classical division into allergic Th2 eosinophilic versus Th1 and/or Th17 neutrophilic (or paucigranulocytic) phenotypes. Rather than having one distinct type of inflammation, many patients display a patchwork of overlapping immune signatures. The patient diversity is further increased by differences in regard of distal lung involvement. Faced with this staggering complexity, calls have been made for a pragmatic biomarker-guided identification of treatable traits. In parallel, novel high-dimensional analyses and multiplex imaging aid the long-term goal of decoding the underlying molecular endotypes.

SUMMARY

Asthma is vastly heterogeneous with multiple and superimposed inflammatory and anatomical phenotypes. Despite the intensive research and introduction of highly immune-selective dugs, basic questions remain; especially as still too many of today's uncontrolled patients remain poorly understood. Here, pragmatic biomarker strategies, combined with novel methodological approaches that ultimately reveal the complete immunological complexity, will pave the way for improved differential diagnosis and personalized medication.

Non-intubated anesthesia in patients undergoing video-assisted thoracoscopic surgery: A systematic review and meta-analysis

INTRODUCTION

Non-intubated anesthesia (NIA) has been proposed for video-assisted thoracoscopic surgery (VATS), although how the benefit-to-risk of NIA compares to that of intubated general anesthesia (IGA) for certain types of patients remains unclear. Therefore, the aim of the present meta-analysis was to understand whether NIA or IGA may be more beneficial for patients undergoing VATS.

METHODS

A systematic search of Cochrane Library, Pubmed and Embase databases from 1968 to April 2019 was performed using predefined criteria. Studies comparing the effects of NIA or IGA for adult VATS patients were considered. The primary outcome measure was hospital stay. Pooled data were meta-analyzed using a random-effects model to determine the standard mean difference (SMD) with 95% confidence intervals (CI).

RESULTS AND DISCUSSION

Twenty-eight studies with 2929 patients were included. The median age of participants was 56.8 years (range 21.9-76.4) and 1802 (61.5%) were male. Compared to IGA, NIA was associated with shorter hospital stay (SMD -0.57 days, 95%CI -0.78 to -0.36), lower estimated cost for hospitalization (SMD -2.83 US, 95% CI -4.33 to -1.34), shorter chest tube duration (SMD -0.32 days, 95% CI -0.47 to -0.17), and shorter postoperative fasting time (SMD, -2.76 days; 95% CI -2.98 to -2.54). NIA patients showed higher levels of total lymphocytes and natural killer cells and higher T helper/T suppressor cell ratio, but lower levels of interleukin (IL)-6, IL-8 and C-reactive protein (CRP). Moreover, NIA patients showed lower levels of fibrinogen, cortisol, procalcitonin and epinephrine.

CONCLUSIONS

NIA enhances the recovery from VATS through attenuation of stress and inflammatory responses and stimulation of cellular immune function.

Does transbronchial lung cryobiopsy give useful information in asthmatic patients?

Introduction

Lung biopsy in asthmatic patients is justified in case of atypical presentations of asthma, when other differential diagnoses, such as hypersensitivity pneumonitis or eosinophilic granulomatosis with polyangiitis, could be possible or for research purposes.

Aim

We aim to describe the utility and the safety of TBLC (transbronchial lung cryobiopsy) in asthmatic patients, providing data on the pathological changes occurring in the airways and in the lung parenchyma.

Methods

We reviewed asthmatic patients that underwent TBLC, that eventually had only a final diagnosis of asthma.

Results

Three patients were detected. TBLC described pathological abnormalities in peribronchiolar and alveolar spaces already well identified with SLB (surgical lung biopsy); the pathological information provided could be useful to better understand the pathobiology of the disease. Finally, we had no complications, confirming a satisfactory safety profile of TBLC.

Conclusion

We suggest the potential role of TBLC in asthmatic patients: its safety and its acceptable diagnostic accuracy lead to consider this procedure instead of SLB when histological changes in lung parenchyma are needed for the differential diagnosis. Furthermore, TLBC could be useful for research in the pathobiology of asthma and severe asthma.