Mycoplasma pneumoniae-associated bronchiolitis causing severe restrictive lung disease in adults: report of three cases and literature review

Mechanism of azithromycin in airway diseases

Azithromycin (AZM) has been used to treat chronic inflammatory airway diseases because it regulates cell–cell contact between airway epithelial cells. Airway mucus hypersecretion is an important component of chronic respiratory diseases. Mucin 5AC (MUC5AC) is the major mucin produced by airway epithelial cells, and hypersecretion of MUC5AC is a sign of various pulmonary inflammatory diseases. Recently, it was found that matrix metallopeptidase 9 is involved in mucus hypersecretion. Moreover, AZM can inhibit the ability of TNF-α-to induce interleukin (IL)-8 production. This review focuses on the effects on AZM that may be beneficial in inhibiting MUC5AC, matrix metalloprotease-9 and IL-8 production in airway epithelial cells. In addition, recent studies have begun to assess activation of mitogen-activated protein kinase (MAPK) signaling pathways in response to AZM. Understanding these new developments may be helpful for clinicians.

Clinicoradiologic features of Mycoplasma pneumoniae bronchiolitis in children

IMPORTANCE

Acute Mycoplasma pneumoniae bronchiolitis can progress into bronchiolitis obliterans (BO) in children, which has a major influence on a child's quality of life and is associated with M. pneumoniae bronchiolitis. Early identification and treatment of M. pneumoniae bronchiolitis is important to prevent the development of BO.

OBJECTIVE

To enhance the understanding of the diagnosis and treatment of M. pneumoniae bronchiolitis in children.

METHODS

Eight patients with M. pneumoniae bronchiolitis were retrospectively analyzed.

RESULTS

Five of the patients with M. pneumoniae bronchiolitis were male and three of them were female. All patients suffered from fever and cough. Moist rales and wheezing were noted in both lungs in six patients. High-resolution computed tomography of the chest showed bronchiolitis in all patients, with large airway injury in two and focal bronchopneumonia in six. Two patients were confirmed to have asthma. Seven patients had personal and/or family histories of atopic diseases. Allergen testing was performed in six patients, which produced positive results in four; the remaining two patients had negative results, but their total IgE levels were > 200 IU/ml. Azithromycin therapy and glucocorticoid therapy was administered to all eight patients. One patient required noninvasive ventilation. Treatment of all patients was successful, with no development of bronchiolitis obliterans during the 4- to 8-month follow-up.

INTERPRETATION

Mycoplasma pneumoniae bronchiolitis can occur in children, especially in atopic individuals. The use, time of initiation, and effects of glucocorticoids administration in these patients for the prevention of BO require further investigation.

Nrf2 regulates the inflammatory response, including heme oxygenase-1 induction, by mycoplasma pneumoniae lipid-associated membrane proteins in THP-1 cells

A series of inflammatory responses caused by Mycoplasma pneumoniae largely depend on the lipid-associated membrane proteins (LAMPs). Nuclear factor E2-related factor 2 (Nrf2), a transcription factor, is considered to be a critical modulator of inflammatory responses and cellular redox homeostasis. Monocytes play an important role in the invasion and immunity to resist pathogens. Here, we investigated the role of Nrf2 in the anti-inflammatory response stimulated by LAMPs using the human monocyte cell line THP-1. LAMPs were shown to affect the localization of Nrf2, and the levels of reactive oxygen species and inflammatory reactants, including nitric oxide (NO), prostaglandin E2 (PGE2) and cytokines (IL-6, IL-8), were highly elevated in LAMP-stimulated Nrf2-silenced THP-1 cells. Moreover, LAMPs induced the levels of mRNA and the expression of heme oxygenase-1 (HO-1). In summary, our results demonstrated that LAMPs cause nuclear translocation of Nrf2, which further suppresses the expression of inflammatory reactants in THP-1 cells.

Mycoplasma pneumoniae-Associated Bronchiolitis Obliterans Following Acute Bronchiolitis

The characteristics of Mycoplasma pneumonia (M. pneumoniae)-associated bronchiolitis obliterans (BO) are not well known. We retrospectively reviewed 17 patients with M. pneumoniae–associated BO. All patients had M. pneumoniae–associated acute bronchiolitis prior to the development of BO. In the acute bronchiolitis stage, all patients had fever and cough; six patients also had wheezing and dyspnoea. BO was diagnosed approximately 1.5–8 months later based on clinical manifestations and chest high-resolution computed tomography (HRCT) findings. All patients presented with wheezing and/or dyspnoea at the time of diagnosis of BO. HRCT findings included mosaic attenuation, pronounced air trapping, central bronchiectasis and emphysema, according to disease severity. Lung function tests revealed mild to severe airway obstruction. Fourteen of 17 patients had a greater than 12% increase in forced expiratory volume in 1 second values after taking salbutamol. All patients had positive allergy test results and family or personal history of atopic disease. Four patients had a history of asthma before M. pneumonia bronchiolitis. Asthma was diagnosed before, at the time of or after the diagnosis of BO in 11 cases. M. pneumoniae–associated BO may therefore develop following M. pneumonia bronchiolitis and overlap with asthma.

Mycoplasma pneumoniae infection: Basics

Mycoplasma pneumoniae (Mp) is one of the leading causes of community‐acquired pneumonia and can cause a number of extrapulmonary manifestations in the absence of pneumonia. In this regard, primary care physicians should know how to suspect, diagnose, and manage patients with Mp infection. This review gives a general overview of the basic clinical aspects of Mp infection with special reference to pneumonia, which will help further understanding of the disease.

Etiology and Outcome of Diffuse Acute Infectious Bronchiolitis in Adults

RATIONALE

The etiology and outcome of diffuse acute infectious bronchiolitis (DAIB) in adults is not well known.

OBJECTIVES

To retrospectively review adult patients with DAIB without pneumonia, document the etiologies and outcomes, and assess the relation between DAIB and postinfectious bronchiolitis obliterans.

METHODS

We retrospectively analyzed medical records of 1,664 patients with lower respiratory tract infections admitted to our institution in Saitama, Japan. DAIB was diagnosed when patients developed acute feverish lower respiratory tract infection and chest computed tomography demonstrated mainly multiple centrilobular nodules in four or more lobes. Pneumonia was diagnosed when patients developed acute feverish lower respiratory tract infection and chest computed tomography demonstrated consolidation and/or ground-glass opacities with or without centrilobular nodules.

MEASUREMENTS AND MAIN RESULTS

Of the 1,664 patients, 20 (1.2%) and 1,644 (98.8%) patients were diagnosed as having DAIB and pneumonia, respectively. Of the 20 patients with DAIB, the etiology was determined in 16 (80%): 13 (65.0%) had a single pathogen and 3 (15.0%) had two pathogens. Detected organisms included Mycoplasma pneumoniae in eight (40.0%) patients, influenza virus in two (10.0%), influenza virus and Streptococcus pneumoniae in two (10.0%), Haemophilus influenzae in three (15.0%), and respiratory syncytial virus and rhinovirus in one (5.0%) patient. All patients improved and none developed postinfectious bronchiolitis obliterans.

CONCLUSIONS

The three most common etiologies of DAIB in the studied adults were M. pneumoniae, influenza virus, and H. influenzae. None of the patients with DAIB developed postinfectious bronchiolitis obliterans.

Correlation between Radiological and Pathological Findings in Patients with Mycoplasma pneumoniae Pneumonia

Studies focused on the pathological-radiological correlation of human Mycoplasma (M) pneumoniae pneumonia have rarely been reported. Therefore, we extensively reviewed the literature regarding pathological and radiological studies of Mycoplasma pneumonia, and compared findings between open lung biopsy specimen and computed tomography (CT). Major three correlations were summarized. (1) Peribronchial and perivascular cuffing characterized by mononuclear cells infiltration was correlated with bronchovascular bundles thickening on CT, which was the most common finding of this pneumonia. (2) Cellular bronchitis in the small airways accompanied with exudates or granulation tissue in the lumen revealed as centrilobular nodules on CT. (3) Neutrophils and exudates in the alveolar lumen radiologically demonstrated as air-space consolidation or ground-glass opacities. In M. pulmonis-infected mice model, pathologic patterns are strikingly different according to host cell-mediated immunity (CMI) levels; treatment with interleukin-2 lead to marked cellular bronchitis in the small airways and treatment with prednisolone or cyclosporin-A lead to neutrophils and exudates in the alveolar lumen. Patients with centrilobular nodules predominant radiologic pattern have a high level of CMI, measuring by tuberculin skin test. From these findings, up-regulation of host CMI could change radiological pattern to centrilobular nodules predominant, on the other hand down-regulation of host CMI would change radiological pattern to ground-glass opacity and consolidation. It was suggested the pathological features of M. pneumoniae pneumonia may be altered by the level of host CMI.

Novel aspects on the pathogenesis of Mycoplasma pneumoniae pneumonia and therapeutic implications

Mycoplasma pneumoniae (Mp) is a leading cause of community acquired pneumonia. Knowledge regarding Mp pneumonia obtained from animal models or human subjects has been discussed in many different reports. Accumulated expertise concerning this critical issue has been hard to apply clinically, and potential problems may remain undiscovered. Therefore, our multidisciplinary team extensively reviewed the literature regarding Mp pneumonia, and compared findings from animal models with those from human subjects. In human beings, the characteristic pathological features of Mp pneumonia have been reported as alveolar infiltration with neutrophils and lymphocytes and lymphocyte/plasma cell infiltrates in the peri-bronchovascular area. Herein, we demonstrated the novel aspects of Mp pneumonia that the severity of the Mp pneumonia seemed to depend on the host innate immunity to the Mp, which might be accelerated by antecedent Mp exposure (re-exposure or latent respiratory infection) through up-regulation of Toll-like receptor 2 expression on bronchial epithelial cells and alveolar macrophages. The macrolides therapy might be beneficial for the patients with macrolide-resistant Mp pneumonia via not bacteriological but immunomodulative effects. This exhaustive review focuses on pathogenesis and extends to some therapeutic implications such as clarithromycin, and discusses the various diverse aspects of Mp pneumonia. It is our hope that this might lead to new insights into this common respiratory disease.

[Post-infectious bronchiolitis obliterans]

Post-infectious bronchiolitis obliterans (BO) is characterized by inflammatory and fibrotic lesions of small airways following a pulmonary infection and leading to some degree of airway obstruction. It represents a rare cause of chronic obstructive pulmonary disease, and is probably underestimated, especially when the lesions affect small areas of the lungs. The clinical features differ between children and adults. In children, adenovirus is the most frequently involved infectious agent, especially the more virulent serotypes 3, 7 and 21. The clinical and radiological signs vary widely and the functional outcome depends on the extent of the lung injury. The diagnosis is based on the medical history, the CT-scan and functional data. The treatment is symptomatic. The most severe forms may result in chronic respiratory insufficiency. In adults, the frequency of obstructive injuries of the small airways in the context of lung infection is unclear. Parenchymal lesions are often present, resulting in BO with organizing pneumonia. These lesions alter the clinical presentation and the radiographic features of the initial infectious disease and often prove difficult to diagnose and manage. Several authors have published clinical cases describing presumed efficacy of systemic corticosteroids but the data are scarce.

Bronchiolitis

Bronchiolitis is a disease of the small airways accompanied by progressive and often irreversible airflow obstruction. Bronchiolitis can have several causes such as infection, toxic exposure, collagen vascular disease, post lung and stem cell transplant, and idiopathic etiology. Symptoms of cough and sputum production are often mistaken for chronic obstructive pulmonary disease or asthma, leading to a delay in diagnosis. Unfortunately, many types of bronchiolitis do not improve with therapy. Bronchiolitis following lung and stem cell transplant are the most common types seen in adults, and provide important insights into its pathogenesis.

Effect of puerarin on the release of interleukin-8 in co-culture of human bronchial epithelial cells and neutrophils

OBJECTIVE

To investigate the effect of puerarin on interleukin (IL)-8 mRNA expression and the protein release in the co-culture of human bronchial epithelial (BEAS-2B) cells and human neutrophils.

METHODS

BEAS-2B cells and neutrophills were cultured separately and co-cultured with puerarin (50, 100, and 200 μg/mL) for a predetermined time. Cytokines in culture supernatant were evaluated by protein array and IL-8 quantified by enzyme-linked immunosorbent assay (ELISA). IL-8 mRNA expression was evaluated by real-time quantitative polymerase chain reaction (real-time qPCR).

RESULTS

The co-culture of BEAS-2B cells and neutrophils exhibited synergistic effects on IL-8 mRNA expression in BEAS-2B cells, but not in neutrophils after 12 h incubation (P<0.01), as compared with that in BEAS-2B cells or neutrophils alone. IL-8 protein release in the culture supernatant was obviously elevated when BEAS-2B cells were co-cultured with human neutrophils as compared with that in the supernatant of BEAS-2B cells or neutrophils alone after incubated for 2, 6, 12, and 18 h (P<0.01). Treatment with puerarin could significantly down-regulate the expression of IL-8 mRNA in BEAS-2B cells and IL-8 release in the supernatant of the co-culture of BEAS-2B cells and neutrophils (P<0.01).

CONCLUSION

Puerarin could exhibit anti-inflammatory activity by suppressing IL-8 production from the co-culture of human bronchial epithelial cells and neutrophils.

Identification of a mechanism for lung inflammation caused by Mycoplasma pneumoniae using a novel mouse model

Human Mycoplasma pneumoniae (MP) pneumonia is characterized by alveolar infiltration with neutrophils and lymphocytes and lymphocyte/plasma cell infiltrates in the peri-bronchovascular area (PBVA). No mouse model has been able to mimic the pathological features seen in human MP pneumonia, such as plasma cell-rich lymphocytic infiltration in PBVA. To figure out the mechanism for inflammation by MP infection using a novel mouse model that mimics human MP pneumonia, mice were pre-immunized intraperitoneally with Th2 stimulating adjuvant, alum, alone or MP extracts with an alum, followed by intratracheal challenge with MP extracts. The toll-like receptor-2, which is the major receptor for mycoplasma cell wall lipoproteins, was strongly up-regulated in alveolar macrophages in a latter group after the pre-immunization but prior to the intratracheal challenge. Those findings demonstrated that acceleration of innate immunity by antecedent antigenic stimulation can be an important positive-feedback mechanism in lung inflammation during MP pneumonia.

Pulmonary surfactant phosphatidylglycerol inhibits Mycoplasma pneumoniae-stimulated eicosanoid production from human and mouse macrophages

Mycoplasma pneumoniae is a human pathogen causing respiratory infections that are also associated with serious exacerbations of chronic lung diseases. Membranes and lipoproteins from M. pneumoniae induced a 4-fold increase in arachidonic acid (AA) release from RAW264.7 and a 2-fold increase in AA release from primary human alveolar macrophages. The bacterial lipoprotein mimic and TLR2/1 agonist Pam3Cys and the TLR2/6 agonist MALP-2 produced effects similar to those elicited by M. pneumoniae in macrophages by inducing the phosphorylation of p38(MAPK) and p44/42(ERK1/2) MAP kinases and cyclooxygenase-2 (COX-2) expression. M. pneumoniae induced the generation of prostaglandins PGD(2) and PGE(2) from RAW264.7 cells and thromboxane B(2) (TXB(2)) from human alveolar macrophages. Anti-TLR2 antibody completely abolished M. pneumoniae-induced AA release and TNFα secretion from RAW264.7 cells and human alveolar macrophages. Disruption of the phosphorylation of p44/42(ERK1/2) or inactivation of cytosolic phospholipase A(2)α (cPLA(2)α) completely inhibited M. pneumoniae-induced AA release from macrophages. The minor pulmonary surfactant phospholipid, palmitoyl-oleoyl-phosphatidylglycerol (POPG), antagonized the proinflammatory actions of M. pneumoniae, Pam3Cys, and MALP-2 by reducing the production of AA metabolites from macrophages. The effect of POPG was specific, insofar as saturated PG, and saturated and unsaturated phosphatidylcholines did not have significant effect on M. pneumoniae-induced AA release. Collectively, these data demonstrate that M. pneumoniae stimulates the production of eicosanoids from macrophages through TLR2, and POPG suppresses this pathogen-induced response.

Organizing pneumonia associated with Mycoplasma pneumoniae infection

Mycoplasma pneumoniae infection is known to produce infiltrative and/or nodular opacities that are often localized. A patient presented to us with diffuse centrilobular, peribronchovascular, and perilobular opacities after documented Mycoplasma pneumoniae infection. A surgical biopsy proved the lung disease to be organizing pneumonia, which dramatically resolved in response to treatment with corticosteroid. This case represents an unusual radiological manifestation associated with M. pneumoniae infection, thereby stressing the importance of this disease in the differential diagnosis for patients with diffuse opacities of the lungs.

Mycoplasma pneumoniae bronchiolitis in adults: clinicoradiologic features and clinical course

The clinicoradiologic features of Mycoplasma pneumoniae bronchiolitis in adults remain unclear. 29 patients with M. pneumoniae infection were collected and classified by computed tomographic findings (bronchiolitis (n=8) and pneumonia (n=21)). M. pneumoniae bronchiolitis is not rare in adults and is clinically similar to M. pneumoniae pneumonia, despite radiographic differences.

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.

Induction of IL-8 by Mycoplasma pneumoniae membrane in BEAS-2B cells

Mycoplasma pneumoniae is an extracellular pathogen, residing on mucosal surfaces of the respiratory and genital tracts. The lack of cell walls in mycoplasmas facilitates the direct contact of the bacterial membrane with the host cell. The cell membrane of mycoplasma is the major inducer of the host pathogenic response. Airway diseases caused by M. pneumoniae include bronchiolitis, bronchitis, and rarely bronchiectasis. In such disorders, neutrophil infiltration of the airways predominates. More recently, M. pneumoniae has been implicated in the pathogenesis of asthma. Epithelial cells play an important role in recruiting inflammatory cells into the airways. Since M. pneumoniae infection of human epithelial cells induces expression of IL-8-a potent activator of neutrophils-we investigated the signaling and transcriptional mechanisms by which mycoplasma membrane induces expression of this chemokine. In BEAS-2B human bronchial epithelial cells, mycoplasma membrane fraction (MMF) increased IL-8 mRNA and protein production. Activation of the transcriptional elements activating protein-1, nuclear factor-interleukin-6, and particularly NF-kappaB are essential for optimal IL-8 production by MMF. The mitogen-activated protein kinases individually played a modest role in MMF-induced IL-8 production. Toll-like receptor-2 did not play a significant role in MMF-induction of IL-8. Antibiotics with microbicidal activity against M. pneumoniae are also known to have anti-inflammatory effects. Whereas clarithromycin, azithromycin, and moxifloxacin individually were able to inhibit TNF-alpha-induction of IL-8, each failed to inhibit MMF-induction of IL-8.

Acute primary Chlamydophila pneumoniae bronchitis and bronchial hyperresponsiveness in young nonasthmatic Thai military recruits

BACKGROUND

A correlation between chronic Chlamydophila pneumoniae infection and chronic airway diseases has been suggested by several studies, but direct evidence to support the link between acute Cpneumoniae infection and new-onset asthma is insufficient.

OBJECTIVES

To determine the association between C. pneumoniae infection and subsequent bronchial hyperresponsiveness (BHR) and hence asthma.

METHODS

We studied 110 Thai military conscripts during an epidemic of Cpneumoniae infection in Thailand, from November 1, 1998, through February 28, 1999. The diagnosis was based on a standardized microimmunofluorescence technique. Spirometry and methacholine challenge tests (MCTs) were conducted. This cohort study excluded all conscripts with preexisting positive MCTs.

RESULTS

Ninety-three percent of the conscripts presented with an acute cough of a mean duration of 15.2 days. The pattern of serologic response revealed that 83% had acute primary infections and 10% had acute reinfections. Mean forced expiratory volume in 1 second was 99.5%, with an improvement of 1.8% after bronchodilator administration. Only 3.6% revealed small airways disease (forced expiratory flow between 25% and 75% of <65%) on spirometry. Methacholine challenge tests failed to demonstrate BHR in all conscripts, and none had developed a new-onset wheeze (physician-diagnosed asthma) at up to 2 years of follow-up.

CONCLUSIONS

This study demonstrates that cough in patients with acute primary Cpneumoniae infection is not associated with BHR among previously healthy adults. The pathogenetic mechanism by which organisms cause coughing and wheezing in acute bronchitis seems to be different among causative respiratory pathogens.

Fatal Mycoplasma pneumoniae pneumonia in a previously healthy 18-year-old girl

A case of fatal Mycoplasma pneumoniae pneumonia in a previously healthy 18-year-old girl is reported. On hospital day 9, the antibody titer to M. pneumoniae was 1:512 in the complement fixation test and 1:5120 in the microparticle agglutination assay. After five weeks in the intensive care unit, the patient died from necrotizing hemorrhagic pneumonia with multi-organ failure. No significant superinfections occurred during ICU treatment. Corticosteroids (hospital day 8 onward) did not influence the course of the disease. It is noteworthy that, as in some previously reported cases, the clinical state deteriorated during presumably adequate antibiotic treatment (2 days before admission onward), and despite documented eradication of the pathogen from the respiratory tract (PCR from bronchoalveolar fluid on hospital day 22 was negative). However, the illness had lasted for several days before admission to the hospital, therefore the potentially beneficial effect of antibiotic treatment at an early stage of the disease cannot be assessed. Clearly, in default of other treatment options, correct diagnosis and early treatment of mycoplasma community-acquired pneumonia seems mandatory. This is the third case of fatal mycoplasma pneumonia reported from Austria in recent years, making this topic worthy of further scientific attention.

Mycoplasma pneumoniae infection increases airway collagen deposition in a murine model of allergic airway inflammation

Mycoplasma pneumoniae (Mp) has been linked to chronic asthma. Airway remodeling (e.g., airway collagen deposition or fibrosis) is one of the pathological features of chronic asthma. However, the effects of respiratory Mp infection on airway fibrosis in asthma remain unclear. In the present study, we hypothesized that respiratory Mp infection may increase the airway collagen deposition in a murine model of allergic airway inflammation in part through upregulation of transforming growth factor (TGF)-beta1. Double (2 wk apart) inoculations of Mp or saline (control) were given to mice with or without previous allergen (ovalbumin) challenges. On days 14 and 42 after the last Mp or saline, lung tissue and bronchoalveolar lavage (BAL) fluid were collected for analyses of collagen and TGF-beta1 at protein and mRNA levels. In allergen-naïve mice, Mp did not alter airway wall collagen. In allergen-challenged mice, Mp infections did not change airway wall collagen deposition on day 14 but increased the airway collagen on day 42; this increase was accompanied by increased TGF-beta1 protein in the airway wall and reduced TGF-beta1 protein release from the lung tissue into BAL fluid. Our results suggest that Mp infections could modulate airway collagen deposition in a murine model of allergic airway inflammation with TGF-beta1 involved in the collagen deposition process.

Emerging intracellular bacterial infections

Human infections by intracellular bacteria have been recognized for many years, but much of what we know about the pathogenesis of these diseases and their etiologic organisms has emerged within the past few years as a result of improved molecular-based means for their detection and classification. New insights concerning the epidemiology and pathogenesis of intracellular bacterial infections and methods for the detection of Chlamydophila pneumoniae, Ehrlichia chaffeensis, Anaplasma phagocytophilum, and Rickettsia species have made an impact on how we view them as agents of human disease. Emerging evidence suggesting a possible intracellular existence for another organism, Mycoplasma pneumoniae, may explain how this organism interacts with the host to induce chronic inflammatory conditions of the respiratory tract.

Bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a disease of small airways that results in progressive dyspnea and airflow limitation. It is a common sequela of bone marrow, lung, and heart-lung transplantation, but can also occur as a complication of certain pulmonary infections, adverse drug reaction, toxic inhalation, and autoimmune disorders. Non-transplant-related BO is rare and can mimic asthma and chronic obstructive pulmonary disease (COPD). In transplant-related BO, the diagnosis can be suggested by obstructive changes in serial pulmonary function testings, while open lung biopsy is usually required in non-transplant cases. High-resolution computerized tomography (HRCT) is also a helpful tool to diagnose and assess the severity of BO. The treatment of BO, regarding of the cause, is usually disappointing. Systemic corticosteroid immunosuppression and retransplantation have been described with variable success.

Imagerie moderne des pneumonies infectieuses aiguës

Les pneumonies infectieuses aiguës constituent un problème de santé publique important, car elles sont une cause majeure de morbidité et de mortalité chez l’adulte. Si les données cliniques et radiographiques permettent le plus souvent de faire le diagnostic de pneumonie infectieuse, le diagnostic étiologique est plus difficile. En effet, de nombreux agents pathogènes peuvent être responsables de pneumonie et la réaction du parenchyme pulmonaire est peu variée, d’où la faible spécificité des lésions radiologiques observées en dehors de quelques cas particuliers. C’est pourquoi la compréhension des mécanismes physiopathologiques permet d’expliquer certains aspects radiologiques. De même, la connaissance des bases anatomocliniques et radiologiques autorise la reconnaissance de trois aspects radiographiques principaux. Quant à l’appréciation des contextes épidémiologique et immunitaire, ils peuvent permettre également d’approcher le germe en cause.

Effects of respiratory Mycoplasma pneumoniae infection on allergen-induced bronchial hyperresponsiveness and lung inflammation in mice

Airway mycoplasma infection may be associated with asthma pathophysiology. However, the direct effects of mycoplasma infection on asthma remain unknown. Using a murine allergic-asthma model, we evaluated the effects of different timing of airway Mycoplasma pneumoniae infection on bronchial hyperresponsiveness (BHR), lung inflammation, and the protein levels of Th1 (gamma interferon [IFN-gamma]) and Th2 (interleukin 4 [IL-4]) cytokines in bronchoalveolar lavage fluid. When mycoplasma infection occurred 3 days before allergen (ovalbumin) sensitization and challenge, the infection reduced the BHR and inflammatory-cell influx into the lung. This was accompanied by a significant induction of Th1 responses (increased IFN-gamma and decreased IL-4 production). Conversely, when mycoplasma infection occurred 2 days after allergen sensitization and challenge, the infection initially caused a temporary reduction of BHR and then increased BHR, lung inflammation, and IL-4 levels. Our data suggest that mycoplasma infection could modulate both physiological and immunological responses in the murine asthma model. Our animal models may also provide a new means to understand the role of infection in asthma pathogenesis and give evidence for the asthma hygiene hypothesis.

Bronchiolitis obliterans with organizing pneumonia associated with acute Coxiella burnetii infection

We report the case of a 62-year-old man who developed bronchiolitis obliterans with organizing pneumonia (BOOP) associated with acute Coxiella burnetii infection. The diagnosis of BOOP was made by fiber-optic transbronchial biopsy. Treatment with corticosteroids resulted in rapid clinical improvement and complete resolution of airspace opacities. To the best of our knowledge, this is the first well-documented case of BOOP associated with C. burnetii infection. This case suggests that this infection might trigger the development of BOOP.

Significant role of interleukin-8 in pathogenesis of pulmonary disease due to Mycoplasma pneumoniae infection

We found elevated levels of interleukin-8 in pleural fluid samples from patients with pleural effusion and with a sustained fibrotic change of the lung due to Mycoplasma pneumoniae infection. This result suggests a critical role of interleukin-8 in the pathogenesis of a certain type of pulmonary disease caused by M. pneumoniae.

Small airways diseases: detection and insights with computed tomography

Diseases affecting the small airways are difficult to detect by traditional diagnostic tests. Widespread involvement is needed before symptoms and abnormalities on pulmonary function testing or chest radiography become apparent. Obstruction of the bronchioles may be detected indirectly by computed tomography (CT) because regional under-ventilation results in reduced perfusion which in turn is shown as a mosaic attenuation pattern of the lung parenchyma. When there is inflammation of the bronchioles with accompanying exudate, the airways may become directly visible on CT, for example in cases of diffuse panbronchiolitis. Quantification of the various morphological features of small airways disease is possible from CT images and this increased precision has aided investigations of structure/function relationships. An understanding of the pathology and microscopic distribution of disease in relation to the airways allows some prediction of the likely computed tomography appearances in this wide spectrum of conditions, and thus helps to refine the differential diagnosis.

Severe acute lung injury caused by Mycoplasma pneumoniae: potential role for steroid pulses in treatment

Published evidence of pathogenetic mechanisms of acute respiratory distress syndrome (ARDS) in mycoplasmal lung infections suggests that the pulmonary injury is related to a cell-mediated immune response. Therefore, steroids may play a role in the treatment of severe cases. We describe a patient who had Mycoplasma pneumoniae pneumonia that progressed to severe ARDS requiring mechanical ventilation and who had improvement with prednisolone pulses.