Diffuse panbronchiolitis in Latin America

Diffuse panbronchiolitis: A progressive fatal lung disease that is curable with azithromycin, but only if diagnosed!

Diffuse panbronchiolitis (DPB) is a rare progressive and eventually fatal pulmonary disease first identified in Japan and initially seen predominantly in Southeast Asia. Macrolide antibiotics rapidly reverse symptoms and pathology, and their use increased the 5 and 10-year survival from 50 and 30 percent, respectively, to over 90%. Review of 181 case reports from previous publications found patients with DPB commonly had their pulmonary symptoms preceded by rhinosinusitis, frequently by many years. Long delays in diagnosis for many years were common. The review further identified DPB in all ethnic groups and multiple areas outside of Southeast Asia. Although diagnosis was most commonly made in adults, 13% of the diagnoses were made in children and nine of the adult cases described onset in childhood. Few cases of relapse were reported, but extended periods of monitoring after treatment were not generally present.

Bronchiolitis: adopting a unifying definition and a comprehensive etiological classification

Bronchiolitis is an inflammatory and potentially fibrosing condition affecting mainly the intralobular conducting and transitional small airways. Secondary bronchiolitis participates in disease process of the airways and/or the surrounding lobular structures in the setting of several already defined clinical entities, mostly of known etiology, and occurs commonly. Primary or idiopathic bronchiolitis dominates and characterizes distinct clinical entities, all of unknown etiology, and occurs rarely. Secondary bronchiolitis regards infections, hypersensitivity disorders, the whole spectrum of smoking-related disorders, toxic fumes and gas inhalation, chronic aspiration, particle inhalation, drug-induced bronchiolar toxicities, sarcoidosis and neoplasms. Idiopathic or primary bronchiolitis defines clinicopathologic entities sufficiently different to be designated as separate disease entities and include cryptogenic constrictive bronchiolitis, diffuse panbronchiolitis, diffuse idiopathic pulmonary neuroendocrine cell hyperplasia, neuroendocrine hyperplasia in infants, bronchiolitis obliterans syndrome in lung and allogeneic hematopoietic cell transplantation, connective tissue disorders, inflammatory bowel disease and bronchiolitis obliterans organizing pneumonia. Most of the above are pathological descriptions used as clinical diagnosis. Acute bronchiolitis, though potentially life threatening, usually regresses. Any etiology chronic bronchiolitis contributes to morbidity and/or mortality if it persists and/or progresses to diffuse airway narrowing and distortion or complete obliteration. Bronchiolitis in specific settings leads to bronchiolectasis, resulting in bronchiectasis.

Diffuse Panbronchiolitis

Diffuse panbronchiolitis (DPB) is characterized by chronic sinobronchial infection and diffuse bilateral micronodular pulmonary lesions consisting of inflammatory cells. Studies on disease etiology point to a genetic predisposition unique to Asians. Early therapy for DPB was largely symptomatic. The advent of macrolide antibiotics, including erythromycin, roxithromycin and clarithromycin, has strikingly changed disease prognosis. Low-dose, long-term macrolide therapy for DPB originated from detailed observations of response to therapy in a single patient. The bactericidal activity of macrolides, particularly erythromycin, is not a significant factor for their clinical efficacy in DPB. Firstly, irrespective of bacterial clearance, clinical improvement is observed in patients treated with erythromycin. Secondly, even in cases with bacterial superinfection with Pseudomonas aeruginosa resistant to macrolides, treatment has proved effective. Thirdly, the recommended dosage of macrolides produces peak levels in tissue that are below the minimum inhibitory concentrations for major pathogenic bacteria that colonize the airway. In the last two decades, the possible mechanism underlying the effectiveness of macrolide therapy has been extensively studied. The proposed mechanism of action includes inhibition of excessive mucus and water secretion from the airway epithelium, inhibition of neutrophil accumulation in the large airway, inhibition of lymphocyte and macrophage accumulation around the small airway, and modulation of bacterial virulence. The great success of macrolide therapy in diffuse panbronchiolitis may extend its application to the treatment of other chronic inflammatory disorders. If the anti-inflammatory activity of macrolides is independent of their bactericidal effect, new anti-inflammatory macrolides without antimicrobial activity should be developed to minimize emergence of macrolide-resistant micro-organisms.

Effect of azithromycin on patients with diffuse panbronchiolitis: retrospective study of 51 cases

BACKGROUND

Patients with diffuse panbronchiolitis (DPB) are routinely treated with erythromycin, clarithromycin, and roxithromycin. The clinical effect of azithromycin on DPB has not been confirmed in a large cohort.

OBJECTIVE

The present study was undertaken to investigate the clinical effects of azithromycin on patients with DPB.

METHODS

Fifty-one patients with DPB treated with azithromycin in Shanghai Pulmonary Hospital, China, from July 2001 to April 2007 were analyzed retrospectively. Azithromycin (500 mg a day) was administrated intravenously in the first 1-2 weeks, taken orally (500 mg, once a day) for 3 months, and tapered to 3 times a week for 6-12 months. The patients were followed up until September 1, 2009. The therapeutic effect, according to their clinical and radiological findings, arterial gas analysis, lung function, and sputum bacterium before and after the therapy, was categorized into the following five grades: 1) cured; 2) improved; 3) no response; 4) aggravation, and 5) relapse.

RESULTS

With azithromycin therapy, 14 (27.5%) patients with DPB were completely cured. The symptoms were eliminated to certain degrees for the other 36 cases (70.6%) of DPB. Five-year survival in this cohort was 94.1%.

CONCLUSION

Azithromycin is effective and well tolerated for patients with diffuse panbronchiolitis.

Padrões tomográficos das doenças intersticiais pulmonares difusas com correlação clínica e patológica

A tomografia de alta resolução (TCAR) é a técnica de imagem radiológica que reflete mais de perto as alterações da estrutura pulmonar. Os vários achados tomográficos podem ser combinados para formar padrões típicos. Estes, conjuntamente com a distribuição anatômica dos achados, e com os dados clínicos, podem estreitar o diagnóstico das doenças intersticiais pulmonares difusas, e em vários casos sugerir o diagnóstico correto com alto grau de acurácia. Os padrões mais comuns das doenças intersticiais pulmonares difusas na TCAR são o nodular, linear e reticular, lesões císticas, opacidades em vidro fosco e consolidações. Este artigo revisa as correlações entre os padrões tomográficos na TCAR e os achados patológicos e resume as causas mais comuns e os métodos de investigação para se atingir um diagnóstico nas doenças pulmonares crônicas difusas mais comuns.

Diffuse panbronchiolitis in East Asia

Diffuse panbronchiolitis is characterized by chronic sinobronchial infection and diffuse bilateral centrilobular lesions consisting of peribronchial infiltration of inflammatory cells. At present, it is known that diffuse panbronchiolitis is relatively restricted to East Asia. This uneven distribution is suspected to be highly associated with genetic predisposition located between human leucocyte antigen-A and -B loci. Low-dose, long-term macrolide therapy for the disease was suggested from a detailed observation of a single case that significantly improved by erythromycin therapy. Otherwise simple bactericidal activity of macrolides has been assumed as a candidate because of their clinical effect on the pathogenesis. In the last 10 years, the possible mechanism underlying the effectiveness of macrolide therapy has been dynamically investigated. To understand the pathological features and potential targets for macrolides in diffuse panbronchiolitis, the authors introduce the incidence of diffuse panbronchiolitis in East Asia, the profile of the disease and then trace the history of macrolide therapy in this review. The proposed mechanism of action includes the inhibition of excessive mucus and water secretion from the airway, the inhibition of neutrophil, and sometimes of lymphocyte and macrophage accumulating in the airway, the inhibition of transcription factors expressing several cytokines and the attenuation of bacterial virulence. Intracellular mechanisms of the action of macrolide are a hot topic of interest in research. The anti-inflammatory activity of macrolides is independent of their bactericidal effect, and a new anti-inflammatory analogue without antimicrobial activity should be developed to minimize the emergence of macrolide-resistant microorganisms and to maintain the safety of this treatment.

Childhood diffuse panbronchiolitis: a case report

Diffuse panbronchiolitis (DPB) is a chronic, potentially life-threatening lower respiratory tract disease that is particularly common in Japanese people. If left untreated, it progresses to bronchiectasis, respiratory failure, and death. Lack of familiarity with DPB in the non-Far East may result in a failure to correctly diagnose and treat this disorder. We describe a child with DPB. We suggest that DPB is a sinopulmonary disease that is not exclusive to the Asian population and to adults. Its clinical and radiological features should be better known by pediatric pulmonary physicians.

The effect of long-term treatment with erythromycin on Th1 and Th2 cytokines in diffuse panbronchiolitis

Diffuse panbronchiolitis (DPB) is a chronic progressive disease of the respiratory bronchioles, and has been improved by low-dose, long-term erythromycin (EMC) treatment. The therapeutic benefits may be derived from its anti-inflammatory and immunomodulatory properties rather than antimicrobial effect. However, there are few studies about the mechanism of immunomodulation by EMC treatment for patient with DPB. In this study, we quantified the changes of Th1 and Th2 cytokines in the bronchoalveolar lavage (BAL) fluid from patients with DPB after long term treatment with EMC. After the EMC treatment, a significant reduction in the number of lymphocytes was observed, and the CD4/CD8 ratio was elevated as well. The IL-2 and IFN-gamma levels in the BAL fluid were significantly decreased and the IL-4, IL-5, and IL-13 levels were significantly increased after EMC treatment. Our results suggest that the therapeutic benefits of long-term EMC treatment may be partially due to the immune system's shift from Th1 to Th2 cytokine production.

The radiological spectrum of small-airway diseases

The small airways of the lungs are an often misunderstood and confusing anatomic location teeming with an array of similar-appearing disease processes that can be daunting even to the most experienced radiologist. This article shows that an understanding of small-airway anatomy and accurate pattern recognition can allow one to determine useful clinical differential diagnoses. The ability to recognize mosaic lung attenuation, and the presence of centrilobular nodules and reticular opacities (tree-in-bud), with or without ground glass, is of critical importance in evaluating this portion of the lung. In addition, we attempt to further show how high-resolution computed tomography (HRCT) scanning has opened the deep recesses of the lung to the thoracic radiologist, allowing for a more meaningful radiologic contribution to the clinical care of patients with unexplained pulmonary symptomatology.