Pulmonary mucoepidermoid carcinoma in children: two case reports and a review of the literature.

Pulmonary mucoepidermoid carcinoma (PMEC) is a rare tumor, particularly in children, and its clinical manifestations vary. When the tumor is small, it may be asymptomatic; however, with larger tumors, patients may present with symptoms such as recurring pneumonia, atelectasis, persistent cough, chest pain, and even hemoptysis. PMEC appears as an exophytic intrabronchial mass. This study aims to report on the clinical manifestations, imaging findings, treatment approaches, and prognosis of two children diagnosed with PMEC at our hospital between January 2018 and December 2022. The age of onset for both children was 9 years, and the masses were located in the right upper lobe bronchi. Following surgical treatment, both patients showed a good prognosis. In addition, we conducted a comprehensive review of the relevant literature to enhance the overall understanding of PMEC.

The clinical application of flexible bronchoscopy in a neonatal intensive care unit.

Objective: Flexible bronchoscopy is widely used in infants and it plays a crucial role. The aim of this study was to investigate the value and clinical safety of flexible bronchoscopy in a neonatal intensive care unit. Methods: A retrospective analysis was performed on the clinical data of 116 neonates who underwent flexible bronchoscopy and the outcomes of 147 procedures. A correlation analysis was performed on the relationship between flexible bronchoscopy findings, microscopic indications, and clinical disease. Results: The 147 procedures performed were due to the following reasons: problems related to artificial airways, 58 cases (39.45%); upper respiratory problems, 60 cases (40.81%) (recurrent dyspnea, 23 cases; upper airway obstruction, 17 cases; recurrent stridor, 14 cases; and hoarseness, six cases), lower respiratory problems, 51 cases (34.69%) (persistent pneumonia, 21 cases; suspicious airway anatomical disease, 21 cases; recurrent atelectasis, eight cases; and pneumorrhagia, one case), feeding difficulty three cases (2.04%). The 147 endoscopic examinations were performed for the following reasons: pathological changes, 141 cases (95.92%); laryngomalacia, 78 cases (53.06%); mucosal inflammation/secretions, 64 cases (43.54%); vocal cord paralysis, 29 cases (19.72%); trachea/bronchus stenosis, 17 cases (11.56%) [five cases of congenital annular constriction of the trachea, seven cases of left main tracheal stenosis, one case of the right middle bronchial stenosis, two cases of tracheal compression, and two cases of congenital tracheal stenosis]; subglottic lesions, 15 cases (10.20%) [eight cases of subglottic granulation tissue, six cases of subglottic stenosis, one cases of subglottic hemangioma]; tracheomalacia, 14 cases (9.52%); laryngeal edema, five cases (3.40%); tracheoesophageal fistula, four cases (2.72%); rhinostenosis, three cases (2.04%); tracheal bronchus, three cases (2.04%); glossoptosis, two cases (1.36%); laryngeal cyst, two cases (1.36%); laryngeal cleft, two cases (1.36%); tongue base cysts, one case (0.68%); and pneumorrhagia, one case (0.68%). Complications were rare and mild. Conclusion: Flexible bronchoscopy is safe and effective for diagnosing and differentiating neonatal respiratory disorders in neonatal intensive care units.

Clinical Features in Patients with Xq23 Microdeletion: A Case Report and Literature Review

Xq22.3-q23 microdeletion is a rare genomic disorder. The purpose of this study was to emphasize the correlation between clinical phenotype and genotype of proximal deletion on chromosome Xq22.3-q23. A 5 years old boy had a 671 KB microdeletion on Xq23 by chromosomal microarray analysis, including AMMECR1 and CHRDL1 genes. He presented with microsomia, midface hypoplasia, right kidney dysplasia and mildly motor retardation, which have not previously been reported in relation to Xq23 deletion. To the best of our knowledge, this is the first case with Xq23 microdeletion. A total of nine cases with microdeletion at Xq22.3-q23 affecting AMMECR1 and two cases with CHRDL1 mutation were reviewed. This review showed that Xq23 microdeletion with microsomia, midface hypoplasia, kidney dysplasia, and mild motor retardation was rare. The previous literature showed two novel point mutations in AMMECR1 and CHRDL1 with some phenotype difference from the presented case. Xq23 microdeletion should be considered for patients with microsomia, midface hypoplasia, kidney dysplasia and growth retardation.

Pulmonary Nocardia infection in a child with idiopathic pulmonary hemosiderosis.

BACKGROUND: Idiopathic pulmonary hemosiderosis (IPH) encompasses a rare and agnogenic group of diffuse alveolar capillary hemorrhagic diseases. Corticosteroid treatment is the globally preferred therapeutic strategy for IPH; however, it can cause immunodeficiency. Nocardia infection often occurs in immunocompromised patients and primarily involves the pleura and lungs. Herein, we describe a case of pediatric pulmonary Nocardia infection after the corticosteroid treatment of IPH. CASE PRESENTATION: A 7-year-old girl presented with chief complaints of pale complexion persisting for 1 year and a cough for 20 days. Abundant hemosiderin-laden macrophages were detected in the gastric juice, which supported the diagnosis of IPH. Uninterrupted doses of corticosteroids were administered during the last hospitalization. After nearly 2 months of corticosteroids therapy, the patient began to cough and produce a purulent sputum. Next-generation sequencing of the bronchoalveolar lavage fluid revealed Nocardia abscessus (N. abscessus) DNA. Linezolid was administered with good response, and the patient was discharged after 18 days of hospitalization. Her symptoms and pulmonary lesions had recovered, and the IPH appeared to be well-controlled with low dose of corticosteroids in follow-up. CONCLUSIONS: Nocardia infection should be considered in the differential diagnoses for IPH patients receiving corticosteroid therapy, especially in patients with poor response to conventional empirical antibiotic therapy. Next-generation sequencing of bronchoalveolar lavage fluid may be used to quickly identify the Nocardia. Sulfonamides or linezolid are effective for pediatric pulmonary Nocardia infection.

Pulmonary Alveolar Proteinosis Due to Pneumocystis carinii in Type 1 Hyper-IgM Syndrome: A Case Report.

Background: Pulmonary alveolar proteinosis (PAP) is a rare diffuse lung disease. Reports of rare cases of PAP due to Pneumocystis jirovecii (P. jirovecii) exist in infants with immunodeficiency diseases, but no cases have been reported to date in pediatric patients with type 1 hyper-IgM syndrome (HIGM1). Case Presentation: Herein, we present a case of PAP secondary to P. jirovecii on an infant with HIGM1. He was admitted to our unit because of cough and tachypnea. Lung biopsy confirmed the diagnosis of PAP, whereas hexamine-silver staining of the bronchoalveolar lavage fluid identified P. jirovecii infection. No other probable cause of PAP was observed. Whole exome sequencing indicated a novel c.511dupA (p.I171N*30) hemizygous mutation in the CD40 ligand (CD40LG) gene. He was cured with bronchoalveolar lavage and compound sulfamethoxazole tablets. Conclusions: To our knowledge, this is the first reported case of P. jirovecii infection as a reversible cause of PAP in an infant with HIGM1.

Plastic bronchitis due to adenoviral infection: a case report.

BACKGROUND: Plastic bronchitis (PB) frequently occurs as a serious postoperative complication of the Fontan procedure. The definitive causes of PB are unknown. CASE PRESENTATION: Herein, we report a pediatric case of PB secondary to adenoviral infection. A 4-year-old girl was admitted to the general pediatric ward for cough since 2 weeks and fever since 11 days. Consolidated lesions were noted in the right upper and both lower lung lobes. Extracorporeal membrane oxygenation was performed because the patient's respiratory failure remained unalleviated despite the use of a ventilator. Bronchial dendritic casts were extracted using flexible bronchoscopy, and the patient's breathing improved. Pathological examination of the dendritic cast confirmed the diagnosis of type I PB. The exfoliated cells of sputum and cells from bronchoalveolar lavage fluid were positive for adenoviral antigen. Human adenovirus 7 was detected by next-generation sequencing of the bronchoalveolar lavage fluid. The patient recovered and was discharged 39 days after admission without recurrence of cough or wheezing. CONCLUSIONS: PB due to human adenovirus 7 infection should be considered in children with persistent respiratory failure. Flexible bronchoscopy should be performed early to confirm diagnosis and to remove any airway obstruction.

Pleuropulmonary blastoma in an infant.

Pleuropulmonary blastomas (PPB) are rare and highly aggressive tumors. Herein, we report an infantile case of type III PPB. A 9-mth-old boy presented to our unit with a history of cough and tachypnea for 2 days. Chest computed tomography revealed a mass in the left upper lobe, emphysema in the left upper lung, and mediastinum and heart shifted towards the right. The mass was removed completely by left upper lobectomy and histology confirmed diagnosis of type III PPB. The immature blastematous tissue was positive for vimentin while benign epithelium was positive for epithelial membrane antigen and cytokeratin. No lymph nodule metastasis was found in the 7 lymph nodules obtained from the hilum of the lung near the tumor. Currently, the patient is under close follow-up and is doing well.

Airway foreign body removal by flexible bronchoscopy: experience with 1027 children during 2000-2008.

BACKGROUND: Foreign body aspiration (FBA) into the tracheobronchial tree is a common problem in children necessitating prompt recognition and management. This study aimed to report our experience in airway foreign body removal by flexible bronchoscopy in children. METHODS: A total of 1027 patients with FBA were reviewed retrospectively. They were 626 boys and 401 girls aged from 5 months to 14 years with a median age of 17 months. The clinical manifestations, radiological findings, bronchoscopic findings and complications of the procedure were analyzed. RESULTS: Among the patients, only 53.4% had a definite history of FBA. The most frequent symptom was paroxysmal cough (84.3%), followed by stridor or wheezing, fever and dyspnea. Chest X-ray showed emphysema in 68.8% of the patients, atelectasis in 13.3% and bronchopneumonia in 56.3%. A bronchoscope was inserted intranasally in most children, but through mouth and endotracheal tube in 17 and 3 children, respectively. Foreign bodies were removed successfully by flexible bronchoscopy with disposable grasping forceps or biopsy forceps in 938 (91.3%) of the patients. The other 89 patients turned to rigid bronchoscopy. During the procedures, 132 (12.9%) of the patients showed transient hypoxia, which was alleviated by oxygen supplement and/or temporary cessation of the procedure. A small amount of bleeding was found in 17 patients and bradycardia in 3. Air leak and laryngeal edema were noted in 2 patients and relieved within 24 hours. CONCLUSIONS: Flexible bronchoscopy is useful and safe in retrieving airway foreign bodies in children. With skilled personnel and perfect equipments, flexible bronchoscopy could be considered as the first choice for the removal of airway foreign body.

Fiberoptic bronchoscopy in neonatal and pediatric intensive care units: a 5-year experience.

OBJECTIVES: To determine the value and safety of fiberoptic bronchoscopy in neonatal and pediatric intensive care units (NICUs, PICUs). SUBJECT AND METHODS: A total of 53 fiberoptic bronchoscopy procedures on 47 patients were reviewed. Bronchoalveolar lavage (BAL) was performed in 23 patients. RESULTS: The primary diseases were pneumonia (n = 16), foreign body aspiration (n = 14), congenital airway abnormality (n = 12), trauma and/or following operations (n = 4) and Guillain-Barré syndrome (n = 1). The major bronchoscopic findings included inflammation in 26 patients, foreign body in 14, congenital airway abnormality in 12 and blood clotting in 3. Microbiology on BAL fluid was positive in 19 of 23 patients. In 23 patients with atelectasis, full and partial re-expansion was obtained in 14 and 6 patients, respectively, at 24 h after the procedures. The clinical features of 9 patients with sputum retention or blood clotting improved significantly after BAL. Positive or negative microbiologic BAL fluid results changed treatment in 11 patients, leading to marked clinical improvement in 9 patients. Moreover, 13 patients were extubated within 24 h of bronchoscopy. CONCLUSION: These data show that fiberoptic bronchoscopy is safe and effective in the diagnosis and therapy of pulmonary disorders in NICUs and PICUs.

The change of asthma-associated immunological parameters in children with Mycoplasma pneumoniae infection.

BACKGROUND: Mycoplasma pneumoniae (M. pneumoniae), an atypical pathogen, is increasingly recognized as a common and important pathogen. Previous studies showed that M. pneumoniae infection may play a role in asthmatic mechanisms based on evidence collected from peripheral blood or sputum of patients or animal models. However, evidence reported from the airways of patients has been rare. OBJECTIVE: To estimate the role of M. pneumoniae infection in asthma by measuring the immunological parameters from peripheral blood and bronchoalveolar lavage fluid (BALF) in pediatric patients with mycoplasma pneumonia. METHODS: A total of 30 patients with mycoplasma pneumonia and 37 patients without M. pneumoniae infection undergoing fiberoptic bronchoscopy were reviewed. The peripheral blood cell count, immunoglobulins (Ig), BALF cell count, and other clinical and laboratory data were reviewed and analyzed. RESULTS: There were significantly more patients with raised basophil counts in the M. pneumoniae group than that in the control group (p = 0.033). Serum immunoglobulin (Ig) A, IgM, and IgG levels in the M. pneumoniae group were significantly higher than those in the control group (p = 0.008, p = 0.011, and p = 0.019, respectively). The percentage of eosinophils in BALF cells was in the range 0 to 10% in M. pneumoniae patients, while it ranged between 0 and 4% in the control group with a significant difference (p = 0.043). In the M. pneumoniae group, we found that the percentage of eosinophils in the BALF cells was positively correlated with age, the percentage of peripheral eosinophils, and BALF lymphocytes (r = 0.298, p = 0.030; r = 0.341, p = 0.014; r = 0.387, p = 0.006; respectively) and negatively correlated with total peripheral white blood cell (r = -0.387, p = 0.005). CONCLUSION: These results suggest that M. pneumonia infection is associated with the asthma mechanism, especially in older children.

Childhood undifferentiated embryonal liver sarcoma: clinical features and immunohistochemistry analysis.

PURPOSE: The aim of the study was to report on 3 cases of childhood undifferentiated embryonal liver sarcoma (UELS) and to highlight the clinical features, laboratory findings, diagnosis, and management of this rare disease. METHODS: The patients' age, sex, clinical features, laboratory findings, pathologic results, and therapy were reviewed. Immunohistochemistry analysis was performed on the resected mass sections. RESULTS: In this study, 2 cases were female (aged 8 and 12 years) and 1 was male (aged 9 years). The causes of hospitalization were mainly abdominal pain, mass, or fever. An elevated erythrocyte sedimentation rate was noted in 2 available cases, and alpha fetoprotein (AFP) was within the normal range. Imaging findings indicated a well-defined heterogeneous large mass in the right lobe. Histopathologic evaluation of the mass confirmed the diagnosis of UELS. Immunohistochemical staining showed that vimentin and CD68 antigen were positive in all samples, whereas desmin was positive in one sample. Surgery with chemotherapy was performed in 2 cases. CONCLUSION: The diagnosis of UELS depends mainly on the pathologic findings. Undifferentiated embryonal liver sarcoma should be included in the differential diagnosis of mass in the liver, especially with well-defined heterogeneous imaging findings and normal AFP. Diagnosis and management should be made early as UELS is a potentially treatable tumor.

Human pentastomiasis in China: case report and literature review.

A 13-yr-old boy was admitted because of persistent fever, abdominal pain and diarrhea for 3 mo. Abdomen CT revealed hepatomegaly and multiple nodular low-density pathological changes. At laparotomy considerable yellow and turbid ascites were seen in the abdominal cavity and miliary nodules were noted on the surface of the omentum majus, liver, and small intestine wall. Histological examination revealed parenchymal tubercles containing several worms. Pathological diagnosis was parasitic granuloma. These parasites were identified as Porocephalus taiwana sp.nov. The patient made an uneventful recovery after therapy and was discharged. Moreover, another 17 cases of human pentastomiasis reported from China were reviewed. Human pentastomiasis is an extremely rare disease and this is only the second case of human Porocephalus taiwana sp.nov infection. Pentastomiasis should be considered in differential diagnosis of patients with a history of abdominal symptoms and eating of poorly-cooked snakes.

Viral pathogens of acute lower respiratory tract infection in China.

OBJECTIVES: To document the viral etiology of acute lower respiratory tract infection (ALRIs) in Chinese children. SETTING: Children Hospital, Zhejiang University, China. STUDY DESIGN: Cross-sectional. PARTICIPANTS: 34885 children with ALRI between January 2001 to December 2006. METHODS: Nasopharyngeal aspirates were collected from all subjects. Respiratory syncytial virus (RSV), adenovirus (ADV), type 1 to 3 parainfluenza viruses (PIV), and type A and B influenza virus (Flu) were detected by direct immunofluorescence. RESULTS: Viruses were identified in 32.3% cases, including RSV (23.6%), PIV 3 (4.3%), Flu A (2.0%), ADV (1.7%), PIV I (0.6%), Flu B (0.2%) and PIV 2 (0.1%). RSV and PIV 3 predominated in younger children while Flu A and Flu B predominated in older children (P<0.001, respectively). PIV 1 was more prevalent in children aged 1 to 3 years. The peak frequency of RSV, PIV 3 and Flu A were in early spring, June to August, and August and September, respectively. Flu B had a peak in the winter and spring. Adenovirus infections occurred in all seasons with a relatively constant frequency. CONCLUSIONS: Viruses are an important cause of ALRIs in Chinese children constituting 1/3 of total cases. RSV is the most common pathogen.

Primary abdominal lymphonodular cryptococcosis in children: 2 case reports and a literature review.

BACKGROUND: Cryptococcus neoformans is an important opportunistic fungal pathogen that is acquired via the respiratory tract. It causes several clinical syndromes and most commonly presents as meningitis. The establishment of C neoformans infections in immunocompetent individuals could be owing to increased virulence, dose of the organism, or genetically determined differences in the ability to generate a protective immune response against the organism. OBJECTIVES: The purpose of this study is to report on 2 case studies and a literature review and to discuss the diagnosis and management of primary abdominal lymphonodular cryptococcosis. METHODS: We conducted 2 case studies and a literature review. RESULTS: Two cases of primary abdominal lymphonodular cryptococcosis in childhood were reported herein. The patients suffered from C neoformans without immunoglobulin or lymphocyte abnormalities. The cause of hospitalization of the 2 cases was mainly the persisting fever with or without abdominal pain. Imaging findings indicated dramatic lymphadenopathy and light hepatosplenomegaly. Excision biopsy of the abnormal lymph node demonstrated reactive lymphoid hyperplasia and the presence of C neoformans. The results of nested polymerase chain reaction confirmed the diagnosis of C neoformans. CONCLUSION: This is the first report on C neoformans in the primary abdominal lymph node in children. This report suggests that C neoformans infection should be considered in the differential diagnosis of fever and marked lymphadenopathy, and empirical administration of antifungal agent may be necessary. C neoformans antibody test, polymerase chain reaction assay, fine-needle aspiration biopsy, or surgical excision biopsy is needed in early diagnosis.

[Viral etiology of pneumonia in children].

OBJECTIVE: To evaluate the viral pathogen of pneumonia in children. METHODS: A total of 13 642 cases of children pneumonia in 3 years were enrolled in this study. Antigens of viral pathogen in respiratory excretion, including respiratory syncytial virus (RSV), type 1, 2 and 3 parainfluenza virus, type A and B influenza virus, and adenovirus were detected by direct immunofluorescence method. RESULTS: Viral pneumonia accounted for 34.3% of all cases, including 25.8% cases of RSV, 4.7% of parainfluenza virus, 2.4% of type A influenza virus, 0.2% of type B influenza virus and 1.3% of adenovirus. Coinfection was found in 20 cases, in which 17 cases (85%) were infected with RSV and another virus. Positive rates of RSV in children < or = 1 year, 1 to 3 years, and >3 years were 33.1%, 19.7% and 5.1% with a significant difference (chi(2)(trend)=763.4, P < 0.001). The positive rate of adenovirus in children < or =1 year (0.7%) was significantly lower than that in children aged 1 to 3 years and in children >3 years (2.3% and 2.5%) (all P<0.01). The positive rate of type A influenza virus in children aged 1 to 3 years was higher than that in children < or =1 year (chi(2)=18.2, P<0.01). Type 1 parainfluenza virus was found in 1.2% children aged 1 to 3 years with most prevalence (P<0.05). Infection rates of type 3 parainfluenza in children < or =1 year, 1 to 3 years, and >3 years were 4.7%, 3.2% and 1.4% respectively with a significant difference (chi(2)(trend)=52.4, P<0.01). Although there were some differences of infection rate of RSV in different years, it tended to increase from November to next April with a highest rate of 62.8%. Type 3 parainfluenza virus and Type A influenza virus were almost sporadic while type A influenza virus was epidemic in August 2003 with an infection rate of 15.7%. CONCLUSION: The highest infection rate of viral pathogen of pneumonia in children is RSV and the follows are parainfluenza, influenza and adenovirus in turn.

Levels of matrix metalloproteinase-9 and its inhibitor in guinea pig asthma model following ovalbumin challenge.

Our objective was to investigate the role of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) and their cellular sources in guinea pig asthma model following ovalbumin (OA) challenge. Twenty guinea pigs were divided into 2 groups: OA-challenged group were sensitized by intraperitoneal injection with OA and exposed to OA while the control group used saline in a similar manner. The positive level index (PLI), defined as the percentage of positive-stained cells x average optical density, was used to assess the expressing levels of MMP-9 and TIMP-1. The levels of MMP-9 from OA-challenged group were significantly higher than those of controls. However, no significant difference of the TIMP-1 levels between the OA-challenged group and controls were found. MMP-9 was expressed strongly in both inflammatory and structural cells while TIMP-1 was expressed weakly in inflammatory cells and structural cells. Our results implied that MMP-9 may contribute to tissue remodeling in asthma and both structural and inflammatory cells within lung tissue are the main cellular sources of MMP-9. Excessive expression of MMP-9 in the early or acute stage of asthma may be associated with the initiation of bronchial injury and inflammatory cells accumulation.

Primary intratracheal neurilemmoma in children: case report and literature review.

A 9-year-old girl was admitted because of recurrent cough, dyspnea, and tachypnea for over 3 months, which had become worse for the preceding week. A chest X-ray revealed a mass in the lumen of the trachea. Fiberoptic bronchoscopy confirmed a polypoid mass in the upper trachea 3 cm under the vocal cords, with a 1.5-cm diameter that occluded approximately 70% of the lumen. Endoscopic excision of the neoplasm was performed with rigid bronchoscopy. Results of immunolabeling, which was positive for S-100 protein and vimentin, demonstrated a benign neurilemmoma. Clinical symptoms and signs improved after the tumor was removed. Intratracheal neurilemmoma is an extremely rare neoplasm, and only 34 cases were previously reported worldwide. The most common presentation is airway obstruction. Preoperative diagnosis is difficult, and radiographic techniques are helpful for diagnosis. Bronchoscopy is recommended for diagnosis, biopsy, and resection of the tumor. Long-term follow-up after simple enucleation is required.

Extracellular matrix remodeling in children with airway foreign-body aspiration.

The purpose of this study was to observe extracellular matrix remodeling in children with airway foreign-body aspiration (FBA) by detecting the expression of matrix metalloproteinase-9 (MMP-9), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and hydroxyproline (HYP) in bronchoalveolar lavage fluid (BALF). Forty-six children with FBA and 12 control subjects from 2002-2003 were enrolled in this study. The former were divided into three subgroups according to duration of foreign-body (FB) retention (subgroup 1, <7 days; subgroup 2, 7-30 days; subgroup 3, >30 days). Cell count, and levels of MMP-9, TIMP-1, and HYP in BALF were measured. The total number of cells and differential counts detected in BALF did not differ significantly between patients and controls (P > 0.05), while mast cells were found only in the BALF of patients. The positive rates of MMP-9 in controls, subgroup 1, subgroup 2, and subgroup 3 were 33.3%, 62.5%, 80.0%, and 93.3%, respectively, with a significant difference (P = 0.006). The positive rate of TIMP-1 in controls and subgroups 1, 2, and 3 were 33.3%, 62.5%, 80.0%, and 93.3%, respectively, with a significant difference (P < 0.001) as well. HYP levels in subgroups 2 and 3 were significantly more increased than in subgroup 1 and controls (all P < 0.001). Levels of MMP-9, TIMP-1, and HYP in patients were positively correlated with duration of FB retention (all P < 0.05), and levels of MMP-9 and TIMP-1 were also positively correlated with percentage of mast cells in BALF (all P < 0.05). The differences in MMP-9 and TIMP-1 before and after FB removed were not significant (P > 0.05), while HYP levels decreased significantly after FB were removed (P = 0.001). Our findings support the hypothesis that FBA may contribute not only to mechanical airway obstruction, but also possibly to eventual airway remodeling by generation of MMPs and TIMPs.