Immunohistochemically stained activated eosinophils in sputum in patients with asthma

Identification of phenotypic clusters of nonsteroidal anti-inflammatory drugs exacerbated respiratory disease

BACKGROUND

Clinical presentation of nonsteroidal anti-inflammatory drugs exacerbated respiratory disease (NERD) is found to be heterogeneous. This study classified phenotypic clusters to determine NERD subtypes.

METHODS

We performed two-step cluster analysis using urticaria, chronic rhinosinusitis (CRS), and atopy, in a NERD cohort comprising 302 patients. Asthma exacerbation was defined as receiving at least one burst of intravenous steroid treatment and/or at least two bursts of oral steroid use (≥ 45 mg/3 days) per year. The possession rate of anti-asthmatic medications was estimated during the follow-up period.

RESULTS

There were four subtypes: subtype 1 (NERD with CRS/atopy and no urticaria), subtype 2 (NERD with CRS and no urticaria/atopy), subtype 3 (NERD without CRS/urticaria), and subtype 4 (NERD with urticaria). Significant differences were found between the four subtypes in the female proportion, baseline FEV1%, serum total IgE level, and sputum/peripheral eosinophil count. A higher frequency of asthma exacerbations was noted in subtype 1 compared to subtype 3. The possession rates of medium- to high-dose inhaled corticosteroids/long-acting beta₂ -agonists showed significant differences among the four subtypes. Metabolomic analysis showed that the four subtypes of NERD had a higher serum leukotriene E4 (LTE4) level than those with aspirin-tolerant asthma. The patients with subtypes 1 and 3 had a higher urine LTE4 level than those with subtype 2.

CONCLUSION

We found four distinct subtypes with different clinical/biochemical findings and asthma exacerbations in a NERD cohort. These findings suggest that stratified strategies by applying subtype classification may help achieve better outcomes in the management of NERD.

Clinical and immunologic findings of methylene diphenyl diisocyanate-induced occupational asthma in a car upholstery factory

BACKGROUND

Although methylene diphenyl diisocyanate (MDI) is widely used in many industries, there have been few immunological studies of MDI-induced occupational asthma.

OBJECTIVES

We investigated the effects of MDI exposure on the clinical and immunologic condition of workers in a single car upholstery factory.

METHODS

Fifty-eight MDI-exposed workers were studied. Work-related lower-respiratory symptoms (WRRS) were identified using a questionnaire. Serum-specific IgE and IgG antibodies to MDI-human serum albumin conjugate were detected by ELISA. Atopy was evaluated using a skin prick test. MDI-induced occupational asthma was confirmed in the symptomatic workers with a positive result on an MDI-specific inhalation test.

RESULTS

Thirteen (22.4%) of the subjects complained of WRRS. MDI-induced occupational asthma was confirmed in five (8.6%) of the workers, and occupational eosinophilic bronchitis was confirmed in two (3.5%). The prevalence of specific IgG antibodies (20.7%) was higher than that of specific IgE antibodies (8.6%). The prevalence of MDI-induced occupational asthma/eosinophilic bronchitis was strongly associated with the presence of both WRRS and serum-specific IgG antibodies to an MDI-human serum albumin conjugate (P<0.01, <0.05, respectively).

CONCLUSION

These findings suggest that MDI could be a causative agent of occupational asthma among MDI-exposed workers. The prevalence of MDI-induced occupational asthma was 8.6%, and MDI-induced eosinophilic bronchitis was confirmed in two workers. The presence of work-related lower-respiratory symptoms and serum-specific IgG antibodies to an MDI-human serum albumin conjugate may be used to predict MDI-induced occupational asthma/eosinophilic bronchitis in MDI-exposed workers.

Histamine release and inflammatory cell infiltration in airway Mucosa in methylene diphenyl diisocyanate (MDI)-induced occupational asthma

INTRODUCTION

Although methylene diphenyl diisocyanate (MDI) is widely used in industries, there have been few studies of the pathogenic mechanisms of MDI-induced occupational asthma (MDI-OA).

METHODS

We performed immunohistochemical analyses, measured inflammatory mediators and cytokines, and quantified histamine release (HR) from peripheral basophils in MDI-OA patients. Thirteen MDI-exposed workers (five MDI-OA, two MDI-induced esoinophilic bronchitis, and six asymptomatic exposed controls, AEC) were enrolled.

RESULTS AND DISCUSSION

Immunochemical analyses indicated significantly increased anti-eosinophilic cationic protein-stained cells in MDI-OA patients as compared with controls (P < 0.05). Sputum eosinophil cationic protein levels were increased after MDI-specific inhalation challenge test in MDI-OA/EB patients (P < 0.02). Sputum eosinophil counts were highly correlated with IL-8 and MMP-9 levels (P < 0.05 and P < 0.01, respectively). Basophil HR was significantly increased in MDI-OA patients after stimulations with anti-IgG4 and MDI-human serum albumin conjugates (both P < 0.05). Eosinophil activation is a major feature of airway inflammation in MDI-OA patients. Increased HR by MDI may contribute to the pathogenic mechanisms of MDI-OA.

Effect of inhaled steroids on increased collagen synthesis in asthma

BACKGROUND

We previously reported that sputum levels of procollagen type I C-terminal peptide (PICP), a marker of ongoing collagen type I deposition, are increased in proportion to airway inflammation in asthma patients.

OBJECTIVES

In this study, we examined the effect of inhaled corticosteroids on increased collagen synthesis in step 2-4 asthmatics.

METHODS

We compared the sputum PICP concentrations of 25 steroid-naive asthmatics, 25 normal volunteers, and 10 subjects with chronic obstructive pulmonary disease. Asthma subjects were also instructed to start fluticasone propionate treatment, and the percentage of forced expiratory volume in 1 s, sputum eosinophil counts, sputum PICP concentrations, and sputum transforming growth factor-beta-positive cell counts before treatment were compared with those 1 month after treatment.

RESULTS

Sputum PICP concentrations were detected in the following order: asthma group >or= chronic obstructive pulmonary disease group > control group. Asthma patients showing high sputum PICP belonged to step 4, although there was no correlation between sputum PICP and asthma severity. Treatment with fluticasone propionate not only significantly improved the mean percentage of forced expiratory volume in 1 s (from 66.7 to 87.2%), but also decreased the mean sputum eosinophil counts (from 13.4 to 5.8%), the mean sputum PICP concentrations (from 30.8 to 10.2 ng/ml), and the mean sputum tumor growth factor-beta-positive cells (from 11.3 to 2.8%). Nevertheless, a significant difference in sputum PICP concentrations was still observed between the control group and the steroid-treated asthma group.

CONCLUSIONS

The present results suggest that inhaled corticosteroid treatment might reduce sputum indexes of collagen metabolism and eosinophilic inflammation in asthma patients.