Bronchiolar disorders

Differences in the anatomy and physiology of the human and rat respiratory tracts and impact on toxicological assessments

Inhalation is a critical route through which substances can exert adverse effects in humans; therefore, it is important to characterize the potential effects that inhaled substances may have on the human respiratory tract by using fit for purpose, reliable, and human relevant testing tools. In regulatory toxicology testing, rats have primarily been used to assess the effects of inhaled substances as they-being mammals-share similarities in structure and function of the respiratory tract with humans. However, questions about inter-species differences impacting the predictability of human effects have surfaced. Disparities in macroscopic anatomy, microscopic anatomy, or physiology, such as breathing mode (e.g., nose-only versus oronasal breathing), airway structure (e.g., complexity of the nasal turbinates), cell types and location within the respiratory tract, and local metabolism may impact inhalation toxicity testing results. This review shows that these key differences describe uncertainty in the use of rat data to predict human effects and supports an opportunity to harness modern toxicology tools and a detailed understanding of the human respiratory tract to develop testing approaches grounded in human biology. Ultimately, as the regulatory purpose is protecting human health, there is a need for testing approaches based on human biology and mechanisms of toxicity.

Association of outcomes in point-of-care lung ultrasound for bronchiolitis in the pediatric emergency department

BACKGROUND

Acute bronchiolitis (AB) is the most common lower respiratory tract infection in infants. Objective scoring tools and plain film radiography have limited application, thus diagnosis is clinical. The role of point-of-care lung ultrasound (LUS) is not well established.

OBJECTIVE

We sought to characterize LUS findings in infants presenting to the pediatric ED diagnosed with AB, and to identify associations between LUS and respiratory support (RS) at 12 and 24 h, maximum RS during hospitalization, disposition, and hospital length of stay (LOS).

METHODS

Infants ≤12 months presenting to the ED and diagnosed with AB were enrolled. LUS was performed at the bedside by a physician. Lungs were divided into 12 segments and scanned, then scored and summated (min. 0, max. 36) in real time accordingly: 0 - A lines with <3 B lines per lung segment. 1 - ≥3 B lines per lung segment, but not consolidated. 2 - consolidated B lines, but no subpleural consolidation. 3 - subpleural consolidation with any findings scoring 1 or 2. Chart review was performed for all patients after discharge. RS was categorized accordingly: RS (room air), low RS (wall O2 or heated high flow nasal cannula <1 L/kg), and high RS (heated high flow nasal cannula ≥1 L/kg or positive pressure).

RESULTS

82 subjects were enrolled. Regarding disposition, the mean (SD) LUS scores were: discharged 1.18 (1.33); admitted to the floor 4.34 (3.62); and admitted to the ICU was 10.84 (6.54). For RS, the mean (SD) LUS scores at 12 h were: no RS 1.56 (1.93), low RS 4.34 (3.51), and high RS 11.94 (6.17). At 24 h: no RS 2.11 (2.35), low RS 4.91 (3.86), and high RS 12.64 (6.48). Maximum RS: no RS 1.22 (1.31), low RS 4.11 (3.61), and high RS 10.45 (6.16). Mean differences for all dispositions and RS time points were statistically significant (p < 0.05, CI >95%). The mean (SD) hospital LOS was 84.5 h (SD 62.9). The Pearson correlation coefficient (r) comparing LOS and LUS was 0.489 (p < 0.0001).

CONCLUSION

Higher LUS scores for AB were associated with increased respiratory support, longer LOS, and more acute disposition. The use of bedside LUS in the ED may assist the clinician in the management and disposition of patient's diagnosed with AB.

Non-infectious Pulmonary Complications in Children with Primary Immunodeficiency

Primary immune deficiency (PID) is a large group of diseases characterized by defective immune function, leading to recurrent infections, and immune dysregulation. Clinical presentations, severity, and complications differ for each disease, based on the components of the immune system that are impacted. When patients with PID present with respiratory symptoms, infections should be initially suspected, investigated, and promptly managed. However, non-infectious complications of PID also frequently occur and can lead to significant morbidity and mortality. They can involve both the upper and lower respiratory systems, resulting in various presentations that mimic infectious diseases. Thus, clinicians should be able to detect these conditions and make an appropriate referral to an immunologist and a pulmonologist for further management. In this article, we use case-based scenarios to review the differential diagnosis, investigation, and multidisciplinary treatment of non-infectious pulmonary complications in patients with primary immune deficiencies.

RSV-induced expanded ciliated cells contribute to bronchial wall thickening

Viral infection, particularly respiratory syncytial virus (RSV), causes inflammation in the bronchiolar airways (bronchial wall thickening, also known as bronchiolitis). This bronchial wall thickening is a common pathophysiological feature in RSV infection, but it causes more fatalities in infants than in children and adults. However, the molecular mechanism of RSV-induced bronchial wall thickening remains unknown, particularly in healthy adults. Using highly differentiated pseudostratified airway epithelium generated from primary human bronchial epithelial cells, we revealed RSV-infects primarily ciliated cells. The infected ciliated cells expanded substantially without compromising epithelial membrane integrity and ciliary functions and contributed to the increased height of the airway epithelium. Furthermore, we identified multiple factors, e.g., cytoskeletal (ARP2/3-complex-driven actin polymerization), immunological (IP10/CXCL10), and viral (NS2), contributing to RSV-induced uneven epithelium height increase in vitro. Thus, RSV-infected expanded cells contribute to a noncanonical inflammatory phenotype, which contributes to bronchial wall thickening in the airway, and is termed cytoskeletal inflammation.

Peribronchiolar Metaplasia: A Marker of Cigarette Smoke-Induced Small Airway Injury in a Rural Cohort

Background

Peribronchiolar metaplasia (PBM) is considered a reaction to injury characterized by the proliferation of bronchiolar epithelium into immediately adjacent alveolar walls. While an association of PBM with diffuse interstitial lung diseases has been recognized, the clinical significance of PBM remains uncertain.

Methods

A cohort (n = 352) undergoing surgical resection of a lung nodule/mass in a rural area was retrospectively reviewed. Multivariate logistic regression analysis was performed to determine the association of PBM with clinical, physiological, radiographic, and histologic endpoints.

Results

In the total study cohort, 9.1% were observed to have PBM as a histologic finding in resected lung tissue (n = 32). All but one of these patients with PBM were ever-smokers with a median of 42 pack years. Clinical COPD was diagnosed in two-thirds of patients with PBM. Comorbid gastroesophageal reflux disease (GERD) was significantly associated with PBM. All patients with PBM demonstrated radiologic and histologic evidence of emphysema. Measures of pulmonary function were not impacted by PBM. Mortality was not associated with the histologic observation of PBM. In a logistic regression model, centrilobular-ground glass opacity interstitial lung abnormality and traction bronchiectasis on the CT scan of the chest and histologic evidence of fibrosis, desquamative interstitial pneumonia and anthracosis all strongly predicted PBM in the cohort.

Conclusion

A constellation of radiologic and histologic smoking-related abnormalities predicted PBM in study cohort. This confirms a co-existence of lung tissue responses to smoking including PBM, emphysema, and fibrosis. Acknowledging the physiologically "silent" nature of small airway dysfunction on pulmonary function testing, our findings support PBM as a histologic marker of small-airway injury associated with cigarette smoking.

RSV-induced Expanded Ciliated Cells Contribute to Bronchial Wall Thickening.. [DOI: 10.1101/2022.10.31.514471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Viral infection, particularly respiratory syncytial virus (RSV), causes inflammation in the bronchiolar airways (bronchial wall thickening, also known as bronchiolitis), reducing airflow through the bronchioles. This bronchial wall thickening is a common pathophysiological feature in RSV infection, but it causes more fatalities in infants than in children and adults. However, the molecular mechanism of RSV-induced bronchial wall thickening remains unknown, particularly in healthy adults. RSV infection in the airway epithelium of healthy adult bronchial cells reveals RSV-infects primarily ciliated cells. RSV infection expands the cell cytoskeleton substantially without compromising epithelial membrane integrity and ciliary functions. The RSV-induced actin cytoskeleton expansion increases ununiformly epithelial height, and cytoskeletal (actin polymerization), immunological (INF-L1, TNF-α, IP10/CXCL10), and viral (NS2) factors are probably responsible. Interestingly, RSV-infected cell cytoskeleton’s expansion resembles a noncanonical inflammatory phenotype, which contributes to bronchial wall thickening, and is termed cytoskeletal inflammation.

Author Summary

RSV infects everyone. Although RSV-induced fatal pathophysiology (e.g., bronchiolitis) is more common in infants than adults, this bronchiolitis (or bronchial wall thickening) is common in the lower respiratory tract due to RSV infection in all ages. To determine the molecular mechanism of RSV-induced bronchial wall thickening, we infectedin vitroadult airway epithelium with RSV. We found that RSV-infection induced a substantial actin-cytoskeleton expansion, consequently increased the height of the epithelium. We identified actin polymerization, secretion of proinflammatory cytokines and chemokines, and viral proteins contribute to the RSV-induced cytoskeletal expansion. Our results suggest that RSV-induces a novel noncanonical epithelial host response termed cytoskeletal inflammation, which may contribute to bronchial wall thickening.

Idiopathic Obliterative Bronchiolitis in a Young Woman: A Rare Case of a Transbronchial Lung Biopsy Contributing to the Diagnosis

Idiopathic obliterative bronchiolitis (OB) is a rare disease that usually requires a surgical lung biopsy. A 25-year-old woman with progressive exertional dyspnea for several months showed a severe mixed restrictive and obstructive pattern on spirometry. Chest computed tomography showed a mosaic pattern, and pulmonary ventilation-perfusion scintigraphy showed a matched defect. The bronchoscopic specimens obtained from both the alveolar and bronchiolar regions of the predicted lesion area contributed to the diagnosis of OB. She had no underlying causes of secondary OB, and she was diagnosed with idiopathic OB. Since lung transplantation was indicated, she was referred to a lung transplantation-certified hospital.

A breath of not so fresh air…

Despite being widely used as a recreational drug, "poppers" lack a legal framework for their delivery. Their composition may vary largely. This report describes a case of severe bronchiolitis following amyl nitrite mixture inhalation. https://bit.ly/3p3S7LM.

Do Not Miss Acute Diffuse Panbronchiolitis for Tree-in-Bud: Case Series of a Rare Lung Disease

Acute bronchiolitis is a common disease of infants affecting the small airways. Rarely, acute bronchiolitis may occur in adolescents and adults. Here, we present four unrelated adolescent patients with severe clinical presentation and unique CT imaging with extensive tree-in-bud pattern, representing a rare clinical phenotype of acute diffuse panbronchiolitis. This characteristic disease pattern caused by inhalation injury from waterpipes, smoked tobacco, and cannabinoids must be differentiated from e-cigarette or vaping product-use-associated lung injury (EVALI). Visual diagnosis of CT and an early diagnostic procedure for detection and differentiation of inhaled hazards, including sample storage for future identification of novel noxious agents, are warranted.

Effects of nebulized epinephrine in association with hypertonic saline for infants with acute bronchiolitis: A systematic review and meta‐analysis

Background

Nebulized epinephrine and hypertonic saline have been extensively studied in infants with acute bronchiolitis, with conflicting results.

Aims

To evaluate the efficacy on length of stay (LOS), clinical severity scores (CSS), oxygen saturation (SaO₂), and safety profile of nebulized epinephrine plus hypertonic saline (HS) in infants with acute bronchiolitis.

Materials & Methods

This is a systematic review and meta‐analysis. Outcomes were represented by mean differences (MD) or standard mean differences (SMD) and 95% confidence intervals (CIs) were utilized.

Results

Eighteen trials were systematically selected and 16 of them contributed to the meta‐analysis (1756 patients). Overall, a modest but significant positive impact was observed of the combination therapy on LOS (MD of –0.35 days, 95% CI −0.62 to −0.08, p = 0.01, I² = 91%). Stratification by time of CSS assessment unveiled positive results in favor of the combination therapy in CSS assessed 48 and 72 h after the admission (SMD of −0.35, 95% CI −0.62 to −0.09, p = 0.008, I² = 41% and SMD of −0.27, 95% CI −0.50 to −0.04, p = 0.02, I² = 0%, respectively). No difference in SaO₂ was observed. Additional data showed a consistent safety profile, with a low rate of adverse events (1%), most of them mild and transient.

Conclusion

Low‐quality evidence from this systematic review suggests that nebulized epinephrine plus HS may be considered as a safe and efficient therapy for decreasing LOS and CSS in infants with acute bronchiolitis, especially in those who require hospitalization for more than 48 h.

Human distal airways contain a multipotent secretory cell that can regenerate alveoli

The human lung differs substantially from its mouse counterpart, resulting in a distinct distal airway architecture affected by disease pathology in chronic obstructive pulmonary disease. In humans, the distal branches of the airway interweave with the alveolar gas-exchange niche, forming an anatomical structure known as the respiratory bronchioles. Owing to the lack of a counterpart in mouse, the cellular and molecular mechanisms that govern respiratory bronchioles in the human lung remain uncharacterized. Here we show that human respiratory bronchioles contain a unique secretory cell population that is distinct from cells in larger proximal airways. Organoid modelling reveals that these respiratory airway secretory (RAS) cells act as unidirectional progenitors for alveolar type 2 cells, which are essential for maintaining and regenerating the alveolar niche. RAS cell lineage differentiation into alveolar type 2 cells is regulated by Notch and Wnt signalling. In chronic obstructive pulmonary disease, RAS cells are altered transcriptionally, corresponding to abnormal alveolar type 2 cell states, which are associated with smoking exposure in both humans and ferrets. These data identify a distinct progenitor in a region of the human lung that is not found in mouse that has a critical role in maintaining the gas-exchange compartment and is altered in chronic lung disease.

Clinical and pathological features of bronchiolitis obliterans requiring lung transplantation in paraneoplastic pemphigus associated with Castleman disease

Summary at a glance

Bronchiolitis obliterans in paraneoplastic pemphigus associated with Castleman disease possesses the progressive nature even when it is treated with intensive medical therapy. Antibodies were at least in low titers before the Lung transplant and remain negative after the procedure. Explanted lungs showed coexistence of cellular destructive bronchiolitis and constrictive bronchiolitis.

Background

Bronchiolitis obliterans (BO) in paraneoplastic pemphigus (PNP) associated with Castleman disease (CD) possesses the progressive nature of pulmonary disease even when it is treated with intensive medical therapy. Lung transplantation (LT) offers an acceptable form of treatment.

Methods

We conducted a retrospective study of two cases of BO in PNP associated with CD who underwent LT between March 2017 and March 2020 at the China‐Japan Friendship Hospital. We also included one case from the literature.

Results

In this patient series, PNP was the primary clinical presentation in all patients, and it was accompanied by respiratory symptoms before/after CD excision. In spite of being treated with various combinations of immunosuppressive and anti‐inflammatory agents, the patients had great or total improvement in mucosal erosions, whereas their pulmonary function test (PFT) deteriorated gradually or sharply. The duration times from disease onset to timing of LT were 1, 2 and 5 years. All antibodies were negative or were present at low titers before the LT procedure and remain negative after the procedure. The histopathological features of explanted lungs showed cellular and coexistent destructive bronchiolitis and constrictive bronchiolitis in two cases. Granulation with numerous foamy macrophages, scattered giant cells and cholesterol clefts were especially prominent in case one.

Conclusion

BO in PNP associated with CD had poor clinical outcomes. LT was preferable choice in end‐stage BO when PNP and CD were controlled.

Sustained Club Cell Injury in Mice Induces Histopathologic Features of Deployment-Related Constrictive Bronchiolitis

Histopathologic evidence of deployment-related constrictive bronchiolitis (DRCB) has been identified in soldiers deployed to Southwest Asia. While inhalational injury to the airway epithelium is suspected, relatively little is known about the pathogenesis underlying this disabling disorder. Club cells are local progenitors critical for repairing the airway epithelium after exposure to various airborne toxins, and a prior study using an inducible transgenic murine model reported that 10 days of sustained targeted club cell injury causes constrictive bronchiolitis. To further understand the mechanisms leading to small airway fibrosis, a murine model was employed to show that sustained club cell injury elicited acute weight loss, caused increased local production of proinflammatory cytokines, and promoted accumulation of numerous myeloid cell subsets in the lung. Transition to a chronic phase was characterized by up-regulated expression of oxidative stress-associated genes, increased activation of transforming growth factor-β, accumulation of alternatively activated macrophages, and enhanced peribronchiolar collagen deposition. Comparative histopathologic analysis demonstrated that sustained club cell injury was sufficient to induce epithelial metaplasia, airway wall thickening, peribronchiolar infiltrates, and clusters of intraluminal airway macrophages that recapitulated key abnormalities observed in DRCB. Depletion of alveolar macrophages in mice decreased activation of transforming growth factor-β and ameliorated constrictive bronchiolitis. Collectively, these findings implicate sustained club cell injury in the development of DRCB and delineate pathways that may yield biomarkers and treatment targets for this disorder.

Airway disease in hematologic malignancies

INTRODUCTION

Hematologic malignancies are cancers of the blood, bone marrow and lymph nodes and represent a heterogenous group of diseases that affect people of all ages. Treatment generally involves chemotherapeutic or targeted agents that aim to kill malignant cells. In some cases, hematopoietic stem cell transplantation (HCT) is required to replenish the killed blood and stem cells. Both disease and therapies are associated with pulmonary complications. As survivors live longer with the disease and are treated with novel agents that may result in secondary immunodeficiency, airway diseases and respiratory infections will increasingly be encountered. To prevent airways diseases from adding to the morbidity of survivors or leading to long-term mortality, improved understanding of the pathogenesis and treatment of viral bronchiolitis, BOS, and bronchiectasis is necessary.

AREAS COVERED

This review focuses on viral bronchitis, BOS and bronchiectasis in people with hematological malignancy. Literature was reviewed from Pubmed for the areas covered.

EXPERT OPINION

Airway disease impacts significantly on hematologic malignancies. Viral bronchiolitis, BOS and bronchiectasis are common respiratory manifestations in hematological malignancy. Strategies to identify patients early in their disease course may improve the efficacy of treatment and halt progression of lung function decline and improve quality of life.

Home-Based Spirometry Telemonitoring After Allogeneic Hematopoietic Cell Transplantation: Mixed Methods Evaluation of Acceptability and Usability

BACKGROUND

Home-based spirometry (HS) allows for the early detection of lung complications in recipients of an allogeneic hematopoietic cell transplant (AHCT). Although the usability and acceptability of HS are critical for adherence, patient-reported outcomes of HS use remain poorly understood in this setting.

OBJECTIVE

The aim of this study is to design a longitudinal, mixed methods study to understand the usability and acceptability of HS among recipients of AHCT.

METHODS

Study participants performed HS using a Bluetooth-capable spirometer that transmitted spirometry data to the study team in real time. In addition, participants completed usability questionnaires and in-depth interviews and reported their experiences with HS. Analysis of interview data was guided by the constructs of performance expectancy, effort expectancy, and social influence from the Unified Theory of Acceptance and Use of Technology model.

RESULTS

Recipients of AHCT found HS to be highly acceptable despite modest technological barriers. On average, participants believed that the HS was helpful in managing symptoms related to AHCT (scores ranging from 2.22 to 2.68 on a scale of 0-4) and for early detection of health-related problems (score range: 2.88-3.12). Participants viewed HS favorably and were generally supportive of continued use. No significant barriers to implementation were identified from the patient's perspective. Age and gender were not associated with the patient perception of HS.

CONCLUSIONS

Study participants found HS acceptable and easy to use. Some modifiable technical barriers to performing HS were identified; however, wider implementation of pulmonary screening is feasible from the patient's perspective.

Diagnosis and management of lung involvement in systemic lupus erythematosus and Sjögren's syndrome: a literature review

Lung involvement in systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS) has extensively been outlined with a multiplicity of different manifestations. In SLE, the most frequent finding is pleural effusion, while in pSS, airway disease and parenchymal disorders prevail. In both cases, there is an increased risk of pre-capillary and post-capillary pulmonary arterial hypertension (PAH) and pulmonary venous thromboembolism (VTE). The risk of VTE is in part due to an increased thrombophilic status secondary to systemic inflammation or to the well-established association with antiphospholipid antibody syndrome (APS). The lung can also be the site of an organ-specific complication due to the aberrant pathologic immune-hyperactivation as occurs in the development of lymphoma or amyloidosis in pSS. Respiratory infections are a major issue to be addressed when approaching the differential diagnosis, and their exclusion is required to safely start an immunosuppressive therapy. Treatment strategy is mainly based on glucocorticoids (GCs) and immunosuppressants, with a variable response according to the primary pathologic process. Anticoagulation is recommended in case of VTE and multi-targeted treatment regimens including different drugs are the mainstay for PAH management. Antibiotics and respiratory physiotherapy can be considered relevant complement therapeutic measures. In this article, we reviewed lung manifestations in SLE and pSS with the aim to provide a comprehensive overview of their diagnosis and management to physicians taking care of patients with connective tissue diseases.

COVID-19 6 months after hospital discharge: pulmonary function impairment and its heterogeneity

Until now, reports about pulmonary function in previously hospitalised subjects for coronavirus disease 2019 (COVID-19) are at discharge [1] or at 3–4 months [2–4]. The first study at 6 months is that of Huanget al. [5], which enrolled 1733 discharged subjects, 349 of whom underwent a pulmonary function study.

After 6 months, about half of #COVID19 discharged subjects present impaired respiratory function with exertional dyspnoea, mainly due a reduced CO diffusion (34%), followed by pulmonary restriction (19%)https://bit.ly/3vcnbdR

Long-Term Imaging Follow-Up in DIPNECH: Multicenter Experience

Diffuse pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare pre-invasive disease whose pathophysiology remains unclear. We aimed to assess long-term evolution in imaging of DIPNECH, in order to propose follow-up recommendations. Patients with histologically confirmed DIPNECH from four centers, evaluated between 2001 and 2020, were enrolled if they had at least two available chest computed tomography (CT) exams performed at least 24 months apart. CT exams were analyzed for the presence and the evolution of DIPNECH-related CT findings. Twenty-seven patients, mostly of female gender (n = 25/27; 93%) were included. Longitudinal follow-up over a median 63-month duration (IQR: 31–80 months) demonstrated an increase in the size of lung nodules in 19 patients (19/27, 70%) and the occurrence of metastatic spread in three patients (3/27, 11%). The metastatic spread was limited to mediastinal lymph nodes in one patient, whereas the other two patients had both lymph node and distant metastases. The mean time interval between baseline CT scan and metastatic spread was 70 months (14, 74 and 123 months). Therefore, long-term annual imaging follow-up of DIPNECH might be appropriate to encompass the heterogeneous longitudinal behavior of this disease.

Interstitial Lung Disease Associated with Connective Tissue Diseases

Pulmonary manifestations of connective tissue diseases (CTD) carry high morbidity and potential mortality, and the most serious pulmonary type is interstitial lung disease (ILD). Identifying and promptly intervening CTD-ILD with immune suppressor therapy will change the natural course of the disease resulting in survival improvement. Compared to idiopathic pulmonary fibrosis, the most common presentation of idiopathic interstitial pneumonia (IIP), CTD-ILD carries a better prognosis due to the response to immune suppressor therapy. Nonspecific interstitial pneumonia (NSIP) is the most common type of CTD-ILD that is different from the fibrotic classical presentation of IPF, known as usual interstitial pneumonia (UIP). An exception is rheumatoid arthritis that presents more frequently with UIP type. Occasionally, IPF may not have typical radiographic features of UIP, and a full assessment to differentiate IPF from CTD-ILD is necessary, including the intervention of a multidisciplinary team and the histopathology. Interstitial pneumonia with autoimmune features (IPAF) shows promising advantages to identify patients with ILD who have some features of a CTD without a defined autoimmune disease and who may benefit from immune suppressors. A composition of clinical, serological, and morphologic features in patients presenting with ILD will fulfill criteria for IPAF. In summary, the early recognition and treatment of CTD-ILD, differentiation from IPF-UIP, and identification of patients with IPAF fulfill the assessment by the clinician for an optimal care.

Overview and Challenges of Bronchiolar Disorders

Bronchiolar abnormalities are common and can occur in conditions that affect either the large airways or the more distal parenchyma. In this review, we focus on the diagnosis and management of primary bronchiolar disorders, or conditions in which bronchiolitis is the predominant pathologic process, including constrictive bronchiolitis, follicular bronchiolitis, acute bronchiolitis, respiratory bronchiolitis, and diffuse panbronchiolitis. Due to the nature of abnormalities in the small airway, clinical and physiological changes in bronchiolitis can be subtle, making diagnosis challenging. Primary bronchiolar disorders frequently present with progressive dyspnea and cough that can be out of proportion to imaging and physiologic studies. Pulmonary function tests may be normal, impaired in an obstructive, restrictive, or mixed pattern, or have an isolated decrease in diffusion capacity. High-resolution computed tomography scan is an important diagnostic tool that may demonstrate one or more of the following three patterns: 1) solid centrilobular nodules, often with linear branching opacities (i.e., "tree-in-bud" pattern); 2) ill-defined ground glass centrilobular nodules; and 3) mosaic attenuation on inspiratory images that is accentuated on expiratory images, consistent with geographic air trapping. Bronchiolitis is often missed on standard transbronchial lung biopsies, as the areas of small airway involvement can be patchy. Fortunately, many patients can be diagnosed with a combination of clinical suspicion, inspiratory and expiratory high-resolution computed tomography scans, and pulmonary function testing. Joint consultation of clinicians with both radiologists and pathologists (in cases where histopathology is pursued) is critical to appropriately assess the clinical-radiographic-pathologic context in each individual patient.

Reflux-Aspiration in Chronic Lung Disease

Microaspiration, or silent aspiration, is commonly suspected in patients with refractory respiratory symptoms, including unexplained chronic cough, asthma, chronic obstructive pulmonary disease, bronchiolitis, bronchiectasis, and idiopathic pulmonary fibrosis. This suspicion is driven by the high prevalence of gastroesophageal reflux in these otherwise disparate disorders. Frequently, patients receive aggressive treatment for gastroesophageal reflux disease as a means of treating their underlying respiratory conditions, even in the absence of overt symptoms of reflux. However, clinical trials have not demonstrated a clear impact on outcomes with this strategy, and in some instances there may be potential for harm. Mechanistic studies have increasingly used gastric biomarkers obtained directly from the airways to confirm the association between reflux and respiratory disease, but results are limited by methodologic flaws and correlation. The best evidence of aspiration directly causing respiratory disorders is the histopathologic detection of foreign bodies. For most of the other chronic respiratory disorders, microaspiration may be uncommon or a secondary aggravating factor, as in patients with acute exacerbations of chronic obstructive pulmonary disease or idiopathic pulmonary fibrosis. In some cases, microaspiration is probably not a significant factor at all, such as in unexplained chronic cough. It is important to distinguish between conditions in which aspiration is primarily or directly causal and conditions in which aspiration may be indirectly aggravating, to help identify whether interventions targeting reflux and aspiration precautions should be recommended to patients. Our clinical review examines some of the evidence supporting reflux-aspiration as a mechanism for several chronic respiratory disorders and offers some management considerations when reflux-aspiration is suspected.

Sjogren's Syndrome and Pulmonary Disease

Sjogren's syndrome is an autoimmune connective tissue disease targeting the exocrine glands and frequently affecting the respiratory system. The pulmonary disease is the most important extra-glandular manifestation as it carries most of the morbidity and mortality. Typically, it affects the small airways ranging from mild to severe respiratory symptoms. The upper airways are also commonly involved, predisposing sinusitis to occur more frequently than in the normal population. Lymphocytic interstitial pneumonia was initially thought to be the prevailing parenchymal disease; however, multiple cohorts report non-interstitial pneumonia to be the most frequent subtype of interstitial lung disease. In the review of high-resolution computed tomography scans, cystic lesions are commonly found and associate with both the small airways and parenchymal disease. Under their presence, amyloidosis or lymphomas should be considered in the differential. Overall, Sjogren's syndrome has a higher risk for lymphoma, and in lungs this condition should be thought of, especially when the images reveal pulmonary nodularity, lymphocytic interstitial pneumonia and lymphadenopathy. Although, pulmonary artery hypertension was traditionally and exceptionally linked with Sjogren's syndrome, together with systemic lupus erythematosus, they are now acknowledged to be the most common pulmonary vascular disease in east Asian populations, even over patients with systemic sclerosis. Although there are no controlled prospective trials to treat pulmonary disease in Sjogren's syndrome, the mainstay treatment modality still falls on glucocorticoid therapy (systemic and inhaled), combined with immune modulators or alone. Most of the evidence sustains successful outcomes based on reported cases or case series.

Occupational Bronchiolitis: An Update

Occupational bronchiolitis is characterized by inflammation of the small airways, and represents a heterogeneous set of lung conditions that can occur following a range of inhalation exposures related to work. The most common clinical presentation includes insidious onset of exertional dyspnea and cough. Multiple reports in recent years have drawn attention to previously unrecognized risk factors for occupational bronchiolitis following exposures in several settings. Both current and past occupational exposures, including prior military deployment-related exposures, should be considered in patients undergoing evaluation for unexplained dyspnea. Diagnostic testing for potential bronchiolitis should include a thorough assessment of the small airways.

Functional parameters of small airways can guide bronchodilator use in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) may present comorbid obstructive lung diseases with small airway dysfunction (SAD). Existing guidelines suggest that inhaled bronchodilators should be used if the ratio of forced expiratory volume in the 1st second and forced vital capacity (FEV₁/FVC) < 0.7 in IPF. However, most IPF patients have FEV₁/FVC > 0.7 even with coexisting emphysema. We retrospectively enrolled IPF patients who were registered at our outpatient clinic. At baseline, 63 patients completed computed tomography (CT) scans, lung function measurements, and symptom questionnaires. Among these patients, 54 (85.71%) underwent antifibrotic treatment and 38 (60.32%) underwent long-acting bronchodilator treatment. The median FEV₁/FVC was 0.86. Not all patients treated with bronchodilators showed significant changes in lung function. IPF patients with SAD, determined by IOS parameters, showed significant improvement in FEV₁, FEF_25–75%, and symptom scores after bronchodilator treatment. Bronchodilator efficacy was not observed in patients without SAD. CT-confirmed emphysema was seen in 34.92% of patients. There were no changes in lung function or symptom scores after bronchodilator treatment in patients with emphysema. In conclusion, FEV₁/FVC cannot reflect the airflow limitation in IPF. Emphysema in IPF is not a deciding factor in whether patients should receive bronchodilator treatment. IOS parameters may be useful to guide bronchodilator therapy in patients with IPF coexisting with SAD.

Bronchoalveolar lavage T cell cytokine profiles and their association with lung function in children with Mycoplasma pneumoniae -associated bronchiolitis obliterans

BACKGROUND

Mycoplasma pneumoniae (M. pneumoniae) infection may progress to bronchiolitis obliterans (BO), with an underlying chronic inflammatory process. The aim of this study was to investigate the cytokine profiles in pulmonary T-lymphocytes and their associations with lung function in patients with BO following M. pneumoniae infection.

METHODS

Bronchoalveolar lavage (BAL) samples were obtained from 10 controls and 18 children with M. pneumoniae-associated BO. We analyzed the BAL T cells for interferon (IFN)-γ, interleukin (IL)-4, IL-9, IL-17, CD25, and Foxp3 by intercellular flow cytometry. The associations with T-cell subpopulations and lung function parameters were determined.

RESULTS

In BAL fluid, significantly increased proportions of T-helper 1 (Th1), Th17, and Tc1 cells were found in M. pneumoniae-associated BO patients when compared with controls. The percentages of Th17 cells showed correlations with forced expiratory volume in 1 second % predicted value (r = -0585; P < .05) and forced expiratory flow at 25% to 75% (FEF_25%-75% ) % predicted value (r = -.618; P < .01). Higher proportions of Tc1 (r = -.488; P < .05) and Tc17 (r = -.542; P < .05) were significantly correlated with a reduced FEF_25%-75% % predicted value in M. pneumoniae-associated BO patients.

CONCLUSIONS

Our comprehensive cytokines analysis of BAL T cells revealed correlations of IL-17-producing and IFN-γ-producing T cells with lung function, suggesting that increased T-cell subpopulations may play a role in M. pneumoniae-associated BO progression.

Cryobiopsy in the diagnosis of bronchiolitis: a retrospective analysis of twenty-three consecutive patients

Bronchiolitis manifests as a variety of histological features that explain the complex clinical profiles and imaging aspects. In the period between January 2011 and June 2015, patients with a cryobiopsy diagnosis of bronchiolitis were retrospectively retrieved from the database of our institution. Clinical profiles, imaging features and histologic diagnoses were analysed to identify the role of cryobiopsy in the diagnostic process. Twenty-three patients with a multidisciplinary diagnosis of small airway disease were retrieved (14 females, 9 males; age range 31-74 years old; mean age 54.2 years old). The final MDT diagnoses were post-infectious bronchiolitis (n = 5), constrictive bronchiolitis (n = 3), DIPNECH (n = 1), idiopathic follicular bronchiolitis (n = 3), Sjogren's disease (n = 1), GLILD (n = 1), smoking-related interstitial lung disease (n = 6), sarcoid with granulomatous bronchiolar disorder (n = 1), and subacute hypersensitivity pneumonitis (n = 2). Complications reported after the cryobiopsy procedure consisted of two cases of pneumothorax soon after the biopsy (8.7%), which were successfully managed with the insertion of a chest tube. Transbronchial cryobiopsy represents a robust and mini-invasive method in the characterization of small airway diseases, allowing a low percentage of complications and good diagnostic confidence.

Chronic Lung Disease in Primary Antibody Deficiency: Diagnosis and Management

Chronic lung disease is a complication of primary antibody deficiency (PAD) associated with significant morbidity and mortality. Manifestations of lung disease in PAD are numerous. Thoughtful application of diagnostic approaches is imperative to accurately identify the form of disease. Much of the treatment used is adapted from immunocompetent populations. Recent genomic and translational medicine advances have led to specific treatments. As chronic lung disease has continued to affect patients with PAD, we hope that continued advancements in our understanding of pulmonary pathology will ultimately lead to effective methods that alleviate impact on quality of life and survival.

Recent advances in the understanding of bronchiolitis in adults

Bronchiolitis is injury to the bronchioles (small airways with a diameter of 2 mm or less) resulting in inflammation and/or fibrosis. Bronchioles can be involved in pathologic processes that involve predominantly the lung parenchyma or large airways, but, in some diseases, bronchioles are the main site of injury ("primary bronchiolitis"). Acute bronchiolitis caused by viruses is responsible for most cases of bronchiolitis in infants and children. In adults, however, there is a wide spectrum of bronchiolar disorders and most are chronic. Many forms of bronchiolitis have been described in the literature, and the terminology in this regard remains confusing. In clinical practice, a classification scheme based on the underlying histopathologic pattern (correlates with presenting radiologic abnormalities) facilitates the recognition of bronchiolitis and the search for the inciting cause of the lung injury. Respiratory bronchiolitis is the most common form of bronchiolitis in adults and is usually related to cigarette smoking. Currently, the diagnosis of respiratory bronchiolitis is generally achieved based on the clinical context (smoking history) and chest CT findings. Constrictive (obliterative) bronchiolitis is associated with airflow obstruction and is seen in various clinical contexts including environmental/occupational inhalation exposures, transplant recipients (bronchiolitis obliterans syndrome), and many others. Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is increasingly recognized and can be associated with progressive airflow obstruction related to constrictive bronchiolitis ("DIPNECH syndrome"). Diffuse aspiration bronchiolitis is a form of aspiration-related lung disease that is often unsuspected and confused for interstitial lung disease. Novel forms of bronchiolitis have been described, including lymphocytic bronchiolitis and alveolar ductitis with emphysema recently described in employees at a manufacturing facility for industrial machines. Bronchiolitis is also a component of vaping-related lung injury encountered in the recent outbreak.

Bronchiolitis Obliterans after Combination Immunotherapy with Pembrolizumab and Ipilimumab

Checkpoint inhibitor therapies are members of a new, groundbreaking class of drugs that reinvigorate the immune system to directly attack tumors. A rare side effect of checkpoint inhibitor therapy is pneumonitis, which typically presents as an interstitial lung disease. In this case report, we present a patient in whom combination therapy with the PD-1 inhibitor pembrolizumab and the CTLA-4 inhibitor ipilimumab induced severe airflow obstruction. This is the first report that shows that checkpoint inhibitors may induce airflow limitation.

Lung regeneration: a tale of mice and men

The respiratory system is the main site of gas exchange with the external environment in complex terrestrial animals. Within the trachea and lungs are multiple different tissue niches each consisting of a myriad of cells types with critical roles in air conduction, gas exchange, providing important niche specific cell-cell interactions, connection to the cardiovascular system, and immune surveillance. How the respiratory system responds to external insults and executes the appropriate regenerative response remains challenging to study given the plethora of cell and tissue interactions for this to occur properly. This review will examine the various cell types and tissue niches found within the respiratory system and provide a comparison between mouse and human lungs and trachea to highlight important similarities and differences. Defining the critical gaps in knowledge in human lung and tracheal regeneration is critical for future development of therapies directed towards respiratory diseases.

Lymphocytic interstitial pneumonia and follicular bronchiolitis in children: A registry-based case series

OBJECTIVES

Pediatric lymphocytic interstitial pneumonia (LIP) and follicular bronchiolitis (FB) are poorly characterized lymphoproliferative disorders. We present and quantify demographics, radiological and histopathologic patterns, treatments and their responses, and outcomes in non-HIV-infected children with LIP and FB.

METHODS

This structured registry-based study included a retrospective chart review, blinded analysis of imaging studies and lung biopsies, genetic testing, and evaluation of treatments and outcomes.

RESULTS

Of the 13 patients (eight females) studied, eight had FB, four had combined LIP/FB, and one had isolated LIP; diagnoses were highly concordant between the pathologists. Most patients became symptomatic during the first 2 years of life, with a mean lag time to diagnosis of 4 years. The most common symptoms were coughing and respiratory infections (11 out of 13 each), dyspnea (10 out of 13), and wheezing (eight out of 13). Autoantibodies were found in eight out of 13 patients. In three patients, disease-causing mutations in the COPA gene were identified. CT revealed hilar lymphadenopathy (five out of 12), ground-glass opacity (eight out of 12), consolidation (five out of 12), and cysts (four out of 13). Systemic steroids as intravenous pulses (11 out of 13) or oral intake (10 out of 13) were the main treatments and showed high response rates of 100% and 90%, respectively. Within the mean observation period of 68 months, all children had chronic courses, eight out of 13 had severe diseases, two died, and one worsened.

CONCLUSIONS

Children with LIP/FB have chronic diseases that occurred in early childhood and were commonly associated with immune dysregulation as well as high morbidity and mortality. Early diagnosis and treatment may be crucial to improve the outcome.

Constrictive Bronchiolitis in Patients With Primary Sjögren Syndrome

OBJECTIVE

Constrictive bronchiolitis (CB) is a poorly understood pulmonary manifestation of primary Sjögren syndrome (pSS). We aimed to clarify the presenting clinicoradiologic features and clinical course of pSS-associated CB through a retrospective cohort study.

METHODS

We retrospectively identified 11 patients with pSS and CB (defined by mosaic pattern with air trapping on computed tomography) encountered at our institution over 9 years from 2007 to 2015. Presenting clinical features, laboratory results, radiologic findings, and clinical course were analyzed.

RESULTS

Our patients were mostly women (91%), with a median age 53 years (range, 31-76 years) at the time of pulmonary symptom (dyspnea or cough) onset. Most (64%) were nonsmokers. Average interval between diagnosis of pSS and the onset of pulmonary symptoms was 4.4 years; in 4 patients (36%), CB was the presenting manifestation of pSS. Chest radiographs were normal (67%) or demonstrated hyperinflation (33%). Pulmonary function testing demonstrated airflow obstruction in 7 patients (63%), and 2 patients (18%) had an isolated reduction in diffusing capacity, whereas the remaining 2 patients manifested mixed physiology or normal results. Surgical lung biopsy was performed in 2 patients and confirmed the diagnosis of CB in both. Treatment was variable among our patients included glucocorticoids, hydroxychloroquine, mycophenolate mofetil, and cyclophosphamide. Among 6 patients with follow-up computed tomography and pulmonary function, the results remained stable or worsened.

CONCLUSIONS

Constrictive bronchiolitis is a rare extraglandular manifestation and can sometimes be the presenting manifestation of pSS. This pulmonary manifestation is associated with an indolent clinical course and does not respond well to immunosuppressive therapy.

Small Airway Disease: A Step Closer to Etiology-Based Classification of Bronchiolitis

Three major histologic patterns of bronchiolitis: obliterative bronchiolitis, follicular bronchiolitis, and diffuse panbronchiolitis, are reviewed in detail. These distinct patterns of primary bronchiolar injury provide a useful starting point for formulating a differential diagnosis and considering possible causes. In support of the aim toward a cause-based classification system of small airway disease, a simple diagnostic algorithm is provided for further subclassification of the above 3 bronchiolitis patterns according to the major associated etiologic subgroups.

An Algorithmic Approach to the Interpretation of Diffuse Lung Disease on Chest CT Imaging: A Theory of Almost Everything

We propose an algorithmic approach to the interpretation of diffuse lung disease on high-resolution CT. Following an initial review of pertinent lung anatomy, the following steps are included. Step 1: a preliminary review of available chest radiographs, including the "scanogram" obtained at the time of the CT examination. Step 2: a review of optimal methods of data acquisition and reconstruction, emphasizing the need for contiguous high-resolution images throughout the entire thorax. Step 3: initial uninterrupted scrolling of contiguous high-resolution images throughout the chest to establish the quality of examination as well as an overview of the presence and extent of disease. Step 4: determination of one of three predominant categories - primarily reticular disease, nodular disease, or diseases associated with diffuse alteration in lung density. Based on this determination, one of the three following Steps are followed: Step 5: evaluation of cases primarily involving diffuse lung reticulation; Step 6: evaluation of cases primarily resulting in diffuse lung nodules; and Step 7: evaluation of cases with diffuse alterations in lung density including those with diffusely diminished lung density vs those with heterogenous or diffusely increased lung density, respectively. It is anticipated that this algorithmic approach will substantially enhance initial interpretations of a wide range of pulmonary disease.

Presumptive Development of Fibrotic Lung Disease From Bordetella bronchiseptica and Post-infectious Bronchiolitis Obliterans in a Dog

A 7-month-old Miniature Poodle acquired from a pet store developed cough and subsequently respiratory distress compatible with Bordetella bronchiseptica infection. Partial but incomplete resolution of clinical signs and thoracic radiographic/computed tomographic imaging lesions were noted with use of susceptibility-guided antimicrobials. Additionally, a concern for an infectious nidus led to left cranial lung lobectomy at 9 months of age. Histopathology predominantly revealed polypoid and constrictive bronchiolitis obliterans (i.e., small airway disease). Intermittent antimicrobial administration over the next 5 years failed to blunt progressive clinical signs. At 8 years, necropsy confirmed severe airway-centered interstitial fibrosis. This pattern of fibrosis was strongly suggestive of underlying small airway disease as the trigger. In retrospect, post-infectious bronchiolitis obliterans (PIBO), a syndrome in young children caused by pulmonary infections but not yet recognized in pet dogs, likely initiated a pathway of fibrosis in this dog. In dogs with risk factors for community-acquired pathogens such as Bordetella bronchiseptica, PIBO is a differential diagnosis with development of severe, persistent respiratory signs incompletely responsive to appropriate antimicrobials. Untreated PIBO may lead to airway-centered interstitial fibrosis. Future study is required to determine if targeted therapy of PIBO could alter the course of end-stage pulmonary fibrosis.

Etiological distribution and clinical features of fever of unknown origin with pulmonary lesions in South China

INTRODUCTION

Fever of unknown origin (FUO) with pulmonary lesions is a common syndrome in respiratory diseases, which can be caused by infection, cancer, connective tissue disease and other rare diseases of South China. In patients with FUO associated with pulmonary lesions, pathogeny should be identified and followed by an appropriate treatment strategy.

OBJECTIVE

This study aimed to investigate the etiological distribution and clinical features of FUO with pulmonary lesions and to analyze the efficiency of different diagnostic methods for certain disease categories.

METHODS

Patients hospitalized at the Guangzhou Institute of Respiratory Health from July 2012 to December 2016 who had fever ≥38.3°C that lasted ≥21 days, in whom the chest X-ray or computed tomography (CT) revealed definite pulmonary infiltration, and for whom, despite being examined for a week, no definitive diagnosis could be made, were considered for this study.

RESULTS

A total of 104 patients were identified as having FUO with lung lesions, and 89.4% (93/104) patients were definitively diagnosed. Infectious disease was the most common cause (46.2%, 48/104). Histopathology was instrumental in the diagnosis of the causes of FUO with pulmonary manifestations, 47.3% (44/93) patients were diagnosed through histopathology, 35.4% (17/48) with infectious disease and 55.2% (16/29) with connective tissue diseases as the etiology were definitely diagnosed using histopathology.

CONCLUSION

Most FUO with pulmonary lesions are identified during infections and autoimmune diseases. The most important diagnostic measure for FUO with pulmonary lesions is histopathology. Additionally, lung biopsy must be encouraged in multi-level hospitals in the future.

Lung Hyperlucency: A Clinical-Radiologic Algorithmic Approach to Diagnosis

Areas of diminished lung density are frequently identified both on routine chest radiographs and chest CT examinations. Colloquially referred to as hyperlucent foci of lung, a broad range of underlying pathophysiologic mechanisms and differential diagnoses account for these changes. Despite this, the spectrum of etiologies can be categorized into underlying parenchymal, airway, and vascular-related entities. The purpose of this review is to provide a practical diagnostic algorithmic approach to pulmonary hyperlucencies incorporating clinical history and characteristic imaging patterns to narrow the differential.

Pulmonary Involvement in Sjögren Syndrome

Sjögren syndrome (SS) is a progressive autoimmune disease characterized by dryness, predominantly of the eyes and mouth, caused by chronic lymphocytic infiltration of the lacrimal and salivary glands. Extraglandular inflammation can lead to systemic manifestations, many of which involve the lungs. Studies in which lung involvement is defined as requiring the presence of respiratory symptoms and either radiograph or pulmonary function test abnormalities quote prevalence estimates of 9% to 22%. The most common lung diseases that occur in relation to SS are airways disease and interstitial lung disease. Evidence-based guidelines to inform treatment recommendations for lung involvement are largely lacking.

Bronchoscopic features, associations, and outcomes of organizing pneumonia following allogeneic hematopoietic stem cell transplantation

Organizing pneumonia (OP) is a poorly understood complication of hematopoietic stem cell transplant (HSCT). We identified 15 patients diagnosed with OP following HSCT and described their clinical course. CT chest findings were remarkable for multifocal infiltrates that were predominantly consolidating or ground glass opacities. Bronchoalveolar lavage (BAL) was performed on 14 patients with five having lymphocytosis (> 25% lymphocytes), three with eosinophilia (> 5% eosinophils), three with neutrophilia (> 30% neutrophils), and three with normal cell counts. Flow cytometry was analyzed on BAL fluid in 13 patients with 11 having a CD4/CD8 of < 0.9. Initial treatment with 0.3–1.0 mg/kg prednisone resulted in improvement in symptoms, in radiographic findings, and in pulmonary function testing for the majority of patients. Six patients had recurrence of OP after completing treatment. Eleven patients had evidence of extra-pulmonary graft-versus-host disease prior to diagnosis of OP, and seven patients were diagnosed with an upper respiratory tract infection (URI) within 8 weeks of OP diagnosis. Most patients respond well to prednisone with significant improvement in pulmonary function, but risk of recurrence is high after cessation of steroid treatment. Risk factors for the development of OP may include prior URI.

Pulmonary Manifestations of Primary Sjögren's Syndrome: Underlying Immunological Mechanisms, Clinical Presentation, and Management

Pulmonary involvement in primary Sjögren's syndrome (pSS) is an understudied entity with important clinical implications. Its prevalence has been reported in up to 20% of pSS patients. Pulmonary manifestations of pSS are diverse with involvement of airway and/or lung parenchyma. Histopathology of lung lesions suggests a predominance of submucosal mononuclear cell infiltration consisting predominantly of CD4+ T cells. Current understanding of the pathophysiology of lung disease in pSS suggests a similar process driving the pulmonary process as those in the salivary glands, with epithelial cells playing a critical role in the initiation, maintenance, and symptomatology of the disease. Clinical manifestations of lung involvement in pSS are as varied as the underlying pathology and can be vague and non-specific, thus delaying diagnosis. Management options depend on the underlying pathology but are generally limited due to lack of systematic randomized controlled trials. This review helps summarize our current understanding of lung involvement in pSS.

Lung ultrasound for prediction of respiratory support in infants with acute bronchiolitis: A cohort study

OBJECTIVE

Respiratory tract infections are among the most common causes of morbidity and mortality worldwide. Acute bronchiolitis (AB) is the leading cause of hospital admission among infants. Clinical scores have proven to be inaccurate in predicting prognosis. Our aim was to build a score based on findings of lung ultrasound (LU) performed at admission, to stratify patients at risk of needing respiratory support (non-invasive and invasive ventilation).

STUDY DESIGN

Prospective, multicenter study including infants <6 months of age admitted with AB. Point-of-care LU was performed on admission, and a score was calculated based on ultrasound findings (presence and localization of B lines, B line confluence and/or consolidations) and clinical data. Main outcome was need of respiratory support.

RESULTS

A total of 145 patients were included in the study, with a median age of 1.7 months [IQR: 1.2-2.8], 47.6% were female. Mean duration of symptoms prior to admission was 3.1 days (SD 1.8). Fifty-six patients (39%) required non-invasive ventilation (NIV), 14 (9.7%) were transferred to PICU, and 3 needed invasive ventilation (3/145). Identification of at least one posterior consolidation >1 cm was the main factor associated to NIV (RR 4.4; [CI95%1.8-10.8]) The LU score built according to the findings on admission showed an AUC: 0.845(CI95%:0.78-0.91). A score ≥3.5 showed a sensitivity of 89.1% (CI95%:78.2-94.9%) and specificity of 56% (CI95%: 45.3-66.1%) CONCLUSIONS: Among infants below 6 months of age admitted with AB, point-of-care LU was a helpful tool to identify patients at risk of needing respiratory support.

The Spectrum of Non-asthmatic Airway Diseases Contributing to Cough in the Adult

PURPOSE OF REVIEW

Cough becomes a pathologic reflex when the airways are inflamed and overwhelmed with excessive mucus. The goal of this review is to discuss acute and chronic cough syndromes caused by non-asthmatic airway diseases.

RECENT FINDINGS

Acute cough syndrome is short-lived and self-limited. Acute bronchitis and diffuse acute infectious bronchiolitis (DAIB) are examples. The former is usually caused by a viral illness; the latter by Mycoplasma pneumoniae, influenza, and Haemophilus influenzae. Causes of chronic cough in the adult include chronic bronchitis, non-infectious bronchiolitis, and non-cystic fibrosis bronchiectasis.

SUMMARY

Supportive measures are recommended for acute bronchitis and antibiotic use is discouraged. Antibiotics may be needed for DAIB. Smoking cessation and bronchodilators can control cough in chronic bronchitis. Therapeutic approaches for non-infectious bronchiolitis depend on the varied etiology. The hallmark of bronchiectasis is a chronic infection of the airways, and antibiotics, mucus clearance measures, and bronchodilators are all supportive.

Perspectives in veterinary medicine: Description and classification of bronchiolar disorders in cats

This Perspectives in Veterinary Medicine article seeks to define, describe putative causes, and discuss key diagnostic tests for primary and secondary bronchiolar disorders to propose a classification scheme in cats with support from a literature review and case examples. The small airways (bronchioles with inner diameters <2 mm), located at the transitional zone between larger conducting airways and the pulmonary acinus, have been overlooked as major contributors to clinical syndromes of respiratory disease in cats. Because the trigger for many bronchiolar disorders is environmental and humans live in a shared environment with similar susceptibility, understanding these diseases in pet cats has relevance to One Health. Thoracic radiography, the major imaging modality used in the diagnostic evaluation of respiratory disease in cats, has low utility in detection of bronchiolar disease. Computed tomography (CT) with paired inspiratory and expiratory scans can detect pathology centered on small airways. In humans, treatment of bronchiolar disorders is not well established because of heterogeneous presentations and often late definitive diagnosis. A review of the human and veterinary medical literature will serve as the basis for a proposed classification scheme in cats. A case series of cats with CT or histopathologic evidence of bronchiolar lesions or both, either as a primary disorder or secondary to extension from large airway disease or interstitial lung disease, will be presented. Future multi‐institutional and multidisciplinary discussions among clinicians, radiologists, and pathologists will help refine and develop this classification scheme to promote early and specific recognition and optimize treatment.

Long-Term Lung Function and Exercise Capacity in Postinfectious chILD

Background: Severe postinfectious diffuse pulmonary disease may clinically mimic other entities of children's interstitial lung disease and is clinically challenging comprising various disease severities despite treatment. Long-term lung function trend and physical capacity in children with postinfectious diffuse pulmonary disease are rarely reported. We investigated trends in pulmonary function by long-term follow-up and assessed physical capacity in such patients.

Methods: We performed a descriptive, single-center follow-up study in children with biopsy-verified postinfectious diffuse pulmonary disease. Patients with completed primary treatment course were eligible for follow-up, including pulmonary function and exercise (VO_2peak) testing.

Results: Thirty patients with postinfectious diffuse pulmonary disease were identified and included. Median (range) age at diagnose was 27.5 (2–172) months after a mean lag time of 23 months. H. influenzae and rhinovirus were the most frequent pathogens. Fifteen patients were available for follow-up after mean (range) 7.6 (2–15) years of treatment completion. Lung clearance index (LCI_2.5), forced expiratory volume in 1 second (FEV₁), and bronchodilator responsiveness were abnormal in 80%, 53%, and 44%, respectively. Diffusion capacity for monoxide was abnormal in 7% and total lung capacity in 33%. Only 8% demonstrated low VO_2peak, while 40% reported difficulties during physical exertion. Longitudinal data on spirometry (n = 14) remained unchanged from end of treatment throughout follow-up. A significant association was found between zLCI_2.5 and zFEV₁ (multiple linear regression; r² = 0.61; P = 0.0003).

Conclusion: Postinfectious diffuse pulmonary disease in children carries a varying degree of chronic pulmonary impairment with onset of symptoms in the first months of life and a typical considerable lag time before diagnosis. Follow-up several years after the initial injury demonstrated moderate-to-severe peripheral airway impairment although no further lung function decline was found years after completion of treatment. Despite acceptable VO_2peak, a considerable proportion struggled during heavy exercise.

The distributive and structural characteristics of bronchus-associated lymphoid tissue (BALT) in Bactrian camels (Camelus bactrianus)

BACKGROUND

Bronchus-associated lymphoid tissue (BALT), distributed in the bronchial mucosa, plays a critical role in maintaining the mucosal immune homeostasis of the lower respiratory tract. The bronchial tree is a functional structure for gas exchange with the outside environment and maintains basic lung morphology.

METHODS

To explore the structural and distributive characteristics of BALT in Bactrian camels, twelve healthy adult Bactrian camels were divided into two groups (six in each group). The lungs, bronchial tree and BALT were observed and analysed systematically through anatomical and histological methods.

RESULTS

The results showed that Bactrian camel lungs were constituted by the left cranial lobe, left caudal lobe, right cranial lobe, right caudal lobe and accessory lobe, but lacked the middle lobe. The cranial lobe was narrow and small, the caudal lobe was extremely developed (almost four times the cranial lobe in size), and the accessory lobe was smaller than the cranial lobe; the bronchial tree, an unequal dichotomy with a tracheobronchial branch, was composed of dorsal, ventral, lateral and medial bronchiole systems. Isolated lymphoid follicles (the chief type) and aggregates of lymphoid follicles revealed two types of BALT, and germinal centres, follicle-associated epithelium and high endothelial venules could be observed in some well-developed BALT. Additionally, BALT was scattered along the bronchial tree in the entire lung, and the density increased from the trachea to the lower graded branches (densest in the bronchioles) and then decreased, with the occasional location around respiratory bronchioles or among the pulmonary mesenchyme. In the conducting portion, BALT was primarily located in the mucosa lamina propria but was also found in the submucosa, under the muscular layer, and around the submucosal glands and cartilage.

CONCLUSION

The results demonstrated that the lung morphology of Bactrian camels was similar to that of horses, but the bronchial branches were more closely related to those of ruminants. These characteristics were in accordance with the morphological and structural variation regularity of lungs with species evolution. BALT was mainly scattered in the conducting portion, and bronchioles, as the final "checkpoint" in the surveillance, capture and recognition of antigens before pulmonary exchange, were the pivotal locational position of BALT. However, BALT at different depths of the bronchial wall of the conducting portion might be at different developmental stages. Our study provided evidence for further insight into the mucosal immunomodulatory mechanism of BALT in the respiratory system of Bactrian camels.