Central Bronchial Deformity in Pulmonary Sarcoidosis: A Finding Suggestive of an Upper Lobe Fibrotic Phenotype on Chest Images.

RATIONALE AND OBJECTIVES: Bronchial and lung parenchymal structural remodeling may occur due to disease progression in patients with pulmonary sarcoidosis; however, its mechanisms remain unclear. Central bronchial deformity (CBD) associated with shrinkage in the upper lobe (SUL) is often observed in such patients. This study aimed to examine the association between CBD and structural remodeling to identify features indicating disease severity on chest images. MATERIALS AND METHODS: This retrospective cohort study included 72 patients with pulmonary sarcoidosis, excluding patients with only bilateral hilar lymphadenopathy. The participants were divided into with and without CBD groups to examine the association between CBD and other structural remodeling, including SUL, cyst and/or low attenuation area-like emphysema (Cyst/LAA), pleural/sub-pleural thickening (PT), and traction bronchiectasis (TrBE), in the upper lobe on chest images. The association of CBD phenotype with respiratory dysfunction was also examined. RESULTS: CBD was highly associated with SUL (81.4% vs. 8.9%), Cyst/LAA (44.4% vs. 6.7%), and PT (59.2% vs. 3.7%). The respective odds ratios in the univariable and multivariable analyses were as follows: SUL, 45.1 and 39.9; Cyst/LAA, 11.2 and 14.2; and PT, 64.0 and 68.7. TrBE was frequently associated with CBD (22.25% vs. 4.4%); the odds ratio was 6.14 in the univariable analysis. Furthermore, participants with CBD exhibited lower %FVC and %DLCO. CONCLUSION: CBD is significantly associated with lung remodeling (SUL, Cyst/LAA, TrBE, and PT) and respiratory dysfunction. CBD may be a crucial clinical phenotype to identify upper lobe fibrotic changes.

Association of serum CC16 levels with eosinophilic inflammation and respiratory dysfunction in severe asthma.

BACKGROUND: There are knowledge gaps in the potential role of Club cell 16-kDa secretory protein (CC16) in severe asthma phenotypes and type 2 inflammation, as well as the longitudinal effect of CC16 on pulmonary function tests and exacerbation risk in epidemiological studies. OBJECTIVE AND METHODS: To assess whether serum CC16 is associated with eosinophilic inflammation in patients with severe asthma. We also examined the effect of this protein on the annual decline in forced expiratory volume in the first second (FEV1) and the risk of exacerbation using a longitudinal approach. We recruited 127 patients with severe asthma from 30 hospitals/pulmonary clinics in Hokkaido, Japan. The least square means and standard error were calculated for T-helper 2 (Th2) biomarkers and pulmonary function test across CC16 tertiles at baseline. We did the same for asthma exacerbation and annual decline in FEV1 with 3 and 5 years' follow-up, respectively. RESULTS: We found that serum CC16 was inversely associated with sputum eosinophils and blood periostin in a dose-response manner. Baseline CC16 and FEV1/forced vital capacity ratio were positively associated in adjusted models (p for trend = 0.008). Patients with the lowest tertile of serum CC16 levels at baseline had a -14.3 mL decline in FEV1 than those with the highest tertile over 5 years of follow-up (p for trend = 0.031, fully adjusted model). We did not find any association of CC16 with exacerbation risk. CONCLUSION: Patients with severe asthma with lower circulatory CC16 had enhanced eosinophilic inflammation with rapid FEV1 decline over time.

Effects of obesity on CC16 and their potential role in overweight/obese asthma.

INTRODUCTION: Club cell secretory protein-16 (CC16) is a major anti-inflammatory protein expressed in the airway; however, the potential role of CC16 on overweight/obese asthma has not been assessed. In this study, we examined whether obesity reduces airway/circulatory CC16 levels using experimental and epidemiological studies. Then, we explored the mediatory role of CC16 in the relationship of overweight/obesity with clinical asthma measures. METHODS: Circulating CC16 levels were assessed by ELISA in three independent human populations, including two groups of healthy and general populations and asthma patients. The percentage of cells expressing club markers in obese vs. non-obese mice and human airways was determined by immunohistochemistry. A causal mediation analysis was conducted to determine whether circulatory CC16 acted as a mediator between overweight/obesity and clinical asthma measures. RESULTS: BMI was significantly and monotonously associated with reduced circulating CC16 levels in all populations. The percentage of CC16-expressing cells was reduced in the small airways of both mice and humans with obesity. Finally, mediation analysis revealed significant contributions of circulatory CC16 in the association between BMI and clinical asthma measures; 21.8% of its total effect in BMI's association with airway hyperresponsiveness of healthy subjects (p = 0.09), 26.4% with asthma severity (p = 0.030), and 23% with the required dose of inhaled corticosteroid (p = 0.042). In logistic regression analysis, 1-SD decrease in serum CC16 levels of asthma patients was associated with 87% increased odds for high dose ICS requirement (p < 0.001). CONCLUSIONS: We demonstrate that airway/circulating CC16, which is inversely associated with BMI, may mediate development and severity in overweight/obese asthma.

Paradoxical Formation of a Pleuroparenchymal Fibroelastosis-like Lesion in the Chronic Course of Pulmonary Sarcoidosis.

We herein report the long-term changes in chest computed tomography (CT) findings from early sarcoidosis lesions to pleuroparenchymal fibroelastosis (PPFE)-like lesions in a 30-year-old man with granulomas on a transbronchial lung biopsy. Multiple bilateral micronodular and nodular opacities around the bronchovascular bundle in the upper lobes detected by chest CT in 2004 disappeared, but paradoxically, peripheral consolidations continued to grow at the periphery of the original lesions. Chest CT in 2017 confirmed the progression of bilateral shrinkage of the upper lobe, spread of peripheral consolidations and wedge-shaped opacities below the first rib, and bronchiectatic air bronchograms, confirming PPFE-like lesions.

Characteristics of patients with a diagnosis of sarcoidosis: a comparison of the 2006 and 2015 versions of diagnostic criteria for sarcoidosis in Japan.

Objective: Histological verification of epithelioid cell granuloma is important in diagnosing sarcoidosis; tissue sampling is a worldwide requirement. In 2006, to reduce medical expenses and avoid invasive procedures, diagnostic criteria without histological verification were permitted by the Japanese government. In 2015, new diagnostic criteria, allowed clinical diagnoses based on only respiratory, ocular, and cardiac systems with at least a two-system involvement, increasing the need to sample tissue from clinically unevaluable organs in suspected sarcoidosis. This study aimed to compare the characteristics of patients who were diagnosed with sarcoidosis according to the 2006 and 2015 criteria. Materials and Methods: Using the 2015 version, we re-evaluated the characteristics of 264 patients with diagnosed or suspected sarcoidosis according to the 2006 criteria, at Jichi Medical University Hospital between 2004 and 2012 (clinical diagnosis, 84; histological diagnosis, 117; suspected sarcoidosis 63). Results: Thirty-nine patients were diagnosed with suspected sarcoidosis due to the absence of at least a two-system involvement; two patients had insufficient laboratory data suggestive of sarcoidosis. Six patients moved from suspected sarcoidosis to a histological diagnosis because of a greater leniency in the criteria for supportive findings. The 2015 diagnostic criteria excluded patients with organ involvement without a requirement for systemic steroids from the clinical diagnosis group. A case of schwannoma, erroneously placed in the clinical diagnosis group by the 2006 criteria, was reclassified according to the 2015 criteria. Conclusion: The 2015 version is preferable for clinically diagnosing sarcoidosis, even without histological specimens, and provides guidance for indications for systemic treatment.

Progression of Central-peripheral Band and Traction Bronchiectasis Clusters Leading to Chronic Respiratory Failure in a Patient with Fibrotic Pulmonary Sarcoidosis.

We herein report a rare case of pulmonary sarcoidosis leading to chronic respiratory failure with restrictive ventilatory impairment during a 53-year-long observation period. Nine years after the histological diagnosis of stage I sarcoidosis on chest X-ray in a woman in her 20s, she developed bilateral reticular and granular opacities on chest computed tomography and was started on prednisone for 18 years. Seven years after prednisone withdrawal, these persisting opacities around the bronchovascular bundle, including a central-peripheral band, had progressed, forming traction bronchiectasis clusters and peripheral cysts, some of which developed continuously at the distal side of these clusters, with eventual upper lobe shrinkage.

Genetic control of CCL24, POR, and IL23R contributes to the pathogenesis of sarcoidosis.

Sarcoidosis is a genetically complex systemic inflammatory disease that affects multiple organs. We present a GWAS of a Japanese cohort (700 sarcoidosis cases and 886 controls) with replication in independent samples from Japan (931 cases and 1,042 controls) and the Czech Republic (265 cases and 264 controls). We identified three loci outside the HLA complex, CCL24, STYXL1-SRRM3, and C1orf141-IL23R, which showed genome-wide significant associations (P < 5.0 × 10-8) with sarcoidosis; CCL24 and STYXL1-SRRM3 were novel. The disease-risk alleles in CCL24 and IL23R were associated with reduced CCL24 and IL23R expression, respectively. The disease-risk allele in STYXL1-SRRM3 was associated with elevated POR expression. These results suggest that genetic control of CCL24, POR, and IL23R expression contribute to the pathogenesis of sarcoidosis. We speculate that the CCL24 risk allele might be involved in a polarized Th1 response in sarcoidosis, and that POR and IL23R risk alleles may lead to diminished host defense against sarcoidosis pathogens.

Honeycomb lung-like structures resulting from clustering of traction bronchiectasis distally in sarcoidosis.

Gene expression profiles of patients with progressive sarcoidosis, most of whom had evidence of fibrosis on imaging, have been reported to be similar to those of patients with inflammatory hypersensitivity pneumonitis, while expression profiles in progressive sarcoidosis did not resemble those of idiopathic pulmonary fibrosis. However, it is not known whether specific parenchymal features discerned on computed tomography (CT) imaging can predict development of fibrosis in pulmonary fibrosis. We herein describe a rare case of pulmonary sarcoidosis with honeycomb lung-like structures developing as a result of concentration of traction bronchiectasis distally, predominantly in both lower lung fields, which developed through shrinkage of consolidations comprising a "central-peripheral band" detected in a woman in her 60s, with non-caseating epithelioid granuloma. To our knowledge, this is the first case demonstrating the distinctive morphology and developmental process of honeycomb lung-like structures in fibrotic pulmonary sarcoidosis.

Computed Tomography Images of Fibrotic Pulmonary Sarcoidosis Leading to Chronic Respiratory Failure.

BACKGROUND: There is currently no consensus on the morphology of severe fibrotic pulmonary sarcoidosis, and we examined computed tomography (CT) findings and progression. METHODS: We analyzed findings in 10 consecutive patients (three men, seven women) with pulmonary sarcoidosis requiring oxygen therapy for chronic respiratory failure, who were extracted from >2500 sarcoidosis patients (three hospitals, 2000-2018). Patients with comorbidities causing chronic respiratory failure were excluded. RESULTS: Predominant findings were consolidations along the bronchovascular bundles comprising 'central-peripheral band', traction bronchiectasis, peripheral cysts/bullae, and upper lobe shrinkage. Traction bronchiectasis arose from opacities comprising 'central-peripheral band'. Clustering of traction bronchiectasis at the distal side formed honeycomb lung-like structures in three patients. Upper lobe shrinkage progressed in seven patients together with progression of consolidations, 'central-peripheral band', traction bronchiectasis clusters, and cysts, while patients without shrinkage included two patients with severe multiple cysts without traction bronchiectasis. Restrictive ventilatory impairment developed in most patients. Pulmonary hypertension (PH) was detected radiologically in five patients, and chronic progressive pulmonary aspergillosis (CPPA) in four patients. CONCLUSIONS: During progression, consolidations comprising 'central-peripheral band' progressed together with traction bronchiectasis clusters and peripheral cysts, resulting in upper lobe shrinkage. This may lead to respiratory failure with possible complications such as PH and CPPA.

Characteristics of 68 patients with clinically proven sarcoidosis based on the Japan Society of Sarcoidosis and Other Granulomatous Disorders 2015 criteria.

BACKGROUND: The presence of histologically evident epithelioid granuloma is required for the diagnosis of sarcoidosis worldwide. The Japan Society of Sarcoidosis and Other Granulomatous Disorders 2015 diagnostic criteria (JSSOG 2015 criteria) includes "clinically proven diagnosis" (involvement of at least 2 of 3 systems confirmed solely by clinical assessment) because of the frequency of sarcoidosis with ocular, cardiac, and respiratory involvement in Japan and the difficulty of obtaining specimens. Here, we describe in detail the clinical presentation of clinically diagnosed sarcoidosis. METHODS: We enrolled 68 consecutive patients with clinically diagnosed sarcoidosis (12 men, 56 women) based on the JSSOG 2015 criteria who were treated at Jichi Medical University between December 2018 and January 2000. We analyzed age at diagnosis, organ involvement, and laboratory findings. RESULTS: Age at diagnosis was unimodal in women. Ocular, splenic, cardiac, and skin involvement, and hypercalcemia were observed in 95.6%, 8.8%, 7.4%, 5.9%, and 35.0% of patients, respectively. High serum lysozyme and soluble interleukin-2 receptor (sIL-2R) levels, bilateral hilar lymphadenopathy on chest radiography, high-grade atrioventricular block or fatal ventricular arrhythmia, and bundle branch block were found in 18.8%, 48.3%, 95.6%, 5.0%, and 10.0% of patients, respectively. CONCLUSIONS: The age-specific distribution of clinically diagnosed sarcoidosis was similar to histologically diagnosed sarcoidosis in women, as previously reported. Rates of elevated serum lysozyme and sIL-2R levels were lower in this study than previously reported in histologically diagnosed patients in Japan.

Nationwide survey on the organ-specific prevalence and its interaction with sarcoidosis in Japan.

Previous studies attempted to characterize the subjects with sarcoidosis according to differences in sex, age, and the presence of specific organ involvement. However, significant interactions among these factors precluded a clear conclusion based on simple comparison. This study aimed to clarify the age- and sex-stratified prevalence of specific organ involvement and the heterogenous nature of sarcoidosis. Using the data of 9,965 patients who were newly registered into a database at the Ministry of Health, Labour and Welfare, Japan between 2002 and 2011, we evaluated the age- and sex-specific prevalence of the eye, lung, and skin involvement of sarcoidosis. We also attempted corresponding analysis considering multiple factors. As compared with several decades ago, the monophasic age distribution in men became biphasic, and the biphasic distribution in women, monophasic. The prevalence of pulmonary and cutaneous lesions was significantly associated with age, whereas the prevalence of ocular involvement showed a biphasic pattern. The prevalence of bilateral hilar lymphadenopathy was significantly higher, whereas the prevalence of diffuse lung shadow was significantly lower, in subjects with ocular involvement than those without ocular involvement. Corresponding analysis visually clarified the complex interactions among factors. Our results contribute to a better understanding of the heterogeneous features of sarcoidosis.

Distinct Phenotypes of Smokers with Fixed Airflow Limitation Identified by Cluster Analysis of Severe Asthma.

RATIONALE: Smoking may have multifactorial effects on asthma phenotypes, particularly in severe asthma. Cluster analysis has been applied to explore novel phenotypes, which are not based on any a priori hypotheses. OBJECTIVES: To explore novel severe asthma phenotypes by cluster analysis when including smoking patients with asthma. METHODS: We recruited a total of 127 subjects with severe asthma, including 59 current or ex-smokers, from our university hospital and its 29 affiliated hospitals/pulmonary clinics. Clinical variables obtained during a 2-day hospital stay were used for cluster analysis. After clustering using clinical variables, the sputum levels of 14 molecules were measured to biologically characterize the clinical clusters. RESULTS: Five clinical clusters, including two characterized by low forced expiratory volume in 1 second/forced vital capacity, were identified. When characteristics of smoking subjects in these two clusters were compared, there were marked differences between the two groups: one had high levels of circulating eosinophils, high immunoglobulin E levels, and a high sinus score, and the other was characterized by low levels of the same parameters. Sputum analysis revealed intriguing differences of cytokine/chemokine pattern in these two groups. The other three clusters were similar to those previously reported: young onset/atopic, nonsmoker/less eosinophilic, and female/obese. Key clinical variables were confirmed to be stable and consistent 3 years later. CONCLUSIONS: This study reveals two distinct phenotypes with potentially different biological pathways contributing to fixed airflow limitation in cigarette smokers with severe asthma.

Serum periostin is associated with body mass index and allergic rhinitis in healthy and asthmatic subjects.

BACKGROUND: Many studies have attempted to clarify the factors associated with serum periostin levels in asthmatic patients. However, these results were based on studies of subjects mainly characterized by high eosinophil counts, which may present as an obstacle for clarification in the identification of other factors associated with serum periostin levels. The aim of this study was to determine the factors associated with serum periostin levels in healthy subjects. We also assessed some factors in asthmatic subjects to confirm their extrapolation for management of asthma. METHODS: Serum periostin levels were measured in 230 healthy subjects. Clinical factors of interest included body mass index (BMI) and allergic rhinitis (AR). Additionally, we confirmed whether these factors were associated with serum periostin in 206 asthmatic subjects. We further evaluated several obesity-related parameters, such as abdominal fat distribution and adipocytokine levels. RESULTS: Smoking status, blood eosinophil count, total immunoglobulin E, and the presence of AR were associated with serum periostin in healthy subjects. There was a negative association between BMI and serum periostin in both healthy and asthmatic subjects, while there was a tendency of a positive association with AR in asthmatic subjects. There were no differential associations observed for subcutaneous and abdominal fat in relation to serum periostin in asthmatic subjects. Serum periostin was significantly associated with serum levels of adiponectin, but not with leptin. CONCLUSIONS: Our results provided clarity as to the factors associated with serum periostin levels, which could be helpful in the interpretation of serum periostin levels in clinical practice.

Resolution rate of pulmonary sarcoidosis and its related factors in a Japanese population.

BACKGROUND AND OBJECTIVE: A number of previous studies have reported on the rate of resolution of pulmonary sarcoidosis and its associated factors. However, most of the studies were conducted several decades ago and no similar surveys have been conducted in recent years. The aim of this study was to evaluate the rate of resolution of pulmonary sarcoidosis and its related factors in recently diagnosed patients, and to compare the results with those from previous studies. METHODS: This study included 306 patients who had been newly diagnosed with pulmonary sarcoidosis between 2000 and 2009 in Sapporo, Japan. Chest radiographical findings were assessed at the initial visit and at the 2- or 5-year observation points. The rates of resolution on chest radiographs and the association with clinical manifestations were evaluated. RESULTS: The resolution rates were 17.9% at the 2-year and 29.9% at the 5-year observation point. These rates were lower than those reported in the earlier surveys. Younger subjects (aged <40 years) showed resolution more often (P < 0.05). The absence of extra-pulmonary organ involvement was associated with resolution at 5 years (P < 0.05). CONCLUSION: The clinical course of pulmonary sarcoidosis may be changing, showing a tendency not to resolve. At least in part, this may be due to the ageing of the Japanese population.

Distinct Phenotypes of Cigarette Smokers Identified by Cluster Analysis of Patients with Severe Asthma.

RATIONALE: Smoking may have multifactorial effects on asthma phenotypes, particularly in severe asthma. Cluster analysis has been applied to explore novel phenotypes, which are not based on any a priori hypotheses. OBJECTIVES: To explore novel severe asthma phenotypes by cluster analysis when including cigarette smokers. METHODS: We recruited a total of 127 subjects with severe asthma, including 59 current or ex-smokers, from our university hospital and its 29 affiliated hospitals/pulmonary clinics. Twelve clinical variables obtained during a 2-day hospital stay were used for cluster analysis. After clustering using clinical variables, the sputum levels of 14 molecules were measured to biologically characterize the clinical clusters. MEASUREMENTS AND MAIN RESULTS: Five clinical clusters were identified, including two characterized by high pack-year exposure to cigarette smoking and low FEV1/FVC. There were marked differences between the two clusters of cigarette smokers. One had high levels of circulating eosinophils, high IgE levels, and a high sinus disease score. The other was characterized by low levels of the same parameters. Sputum analysis revealed increased levels of IL-5 in the former cluster and increased levels of IL-6 and osteopontin in the latter. The other three clusters were similar to those previously reported: young onset/atopic, nonsmoker/less eosinophilic, and female/obese. Key clinical variables were confirmed to be stable and consistent 1 year later. CONCLUSIONS: This study reveals two distinct phenotypes of severe asthma in current and former cigarette smokers with potentially different biological pathways contributing to fixed airflow limitation. Clinical trial registered with www.umin.ac.jp (000003254).

The WASOG Sarcoidosis Organ Assessment Instrument: An update of a previous clinical tool.

INTRODUCTION: A Case Control Etiology of Sarcoidosis Study (ACCESS) sarcoidosis organ assessment instrument has been used for more than a decade to establish uniform standards for the probability of sarcoidosis organ involvement. The ACCESS instrument has become increasingly outdated as new technologies have been developed. Furthermore, the ACCESS instrument failed to address all possible organs involved with sarcoidosis. For these reasons, the World Association of Sarcoidosis and Other Granulomatous Diseases (WASOG) developed a new sarcoidosis organ assessment instrument. METHODS: Clinical sarcoidosis experts assessed various clinical manifestations for the probability of sarcoidosis organ involvement. Two criteria were required to apply this assessment: 1) histologic evidence of granulomatous inflammation of unknown cause in an organ that was not being assessed; 2) the clinical manifestation being addressed required that alternative causes other than sarcoidosis had been reasonably excluded. Clinical manifestations were assessed as either: a) highly probable: likelihood of sarcoidosis causing this manifestation of at least 90%.; b) probable: likelihood of sarcoidosis causing this manifestation of between 50 and 90%; c) possible: likelihood of sarcoidosis causing this manifestation of less than 50%. The sarcoidosis experts voted on the likelihood of sarcoidosis causing each manifestation using Delphi study methodology where at least 70% agreement of the experts was needed for consensus. RESULTS: Various clinical manifestations were classified as highly probable, at least probable, possible, or indeterminate when no consensus could be reached. CONCLUSION: An instrument was developed by expert opinion that may be useful for the clinician and researcher in establishing criteria for sarcoidosis organ involvement.

The CC16 A38G polymorphism is associated with asymptomatic airway hyper-responsiveness and development of late-onset asthma.

BACKGROUND: Clara cell secretory protein (CC16) is expressed primarily in the respiratory tract and is a potent anti-inflammatory agent that protects the airway from inflammation. The associations of the A38G polymorphism in this gene with asymptomatic airway hyper-responsiveness (AHR), which is considered a risk factor for future asthma in adults, and the development of adult-onset asthma are unclear. OBJECTIVE: To evaluate the association of the CC16 A38G polymorphism with asymptomatic AHR in healthy young adults and the development of adult-onset asthma and the association between plasma CC16 level according to this genotype and asymptomatic AHR. METHODS: Nonspecific AHR was measured in 154 asymptomatic, young, healthy adults using a continuous methacholine inhalation method. The cumulative dose values of inhaled methacholine measured at the inflection point at which respiratory conductance started to decrease (Dmin) were used as an index of AHR. Case-control analysis was performed for the association between this polymorphism and the development of asthma in 1,086 unrelated Japanese subjects (504 subjects with asthma and 582 healthy subjects). RESULTS: The 38AA + AG genotype was associated with lower Dmin values and lower plasma CC16 levels (P = .012 and .020). There was a significant positive correlation between Dmin values and plasma CC16 levels (P = .012). In the case-control study, the 38AA + AG genotype was significantly associated with late-onset asthma (onset at >40 years; odds ratio, 1.63; P = .016). CONCLUSION: These results suggest that the CC16 A38G polymorphism may play a role in asymptomatic AHR and contribute to the development of late-onset asthma.

Increased prevalence of cigarette smoking in Japanese patients with sarcoidosis.

BACKGROUND AND OBJECTIVE: Several studies have shown that individuals with sarcoidosis in Western populations are less likely to have smoked before diagnosis. Epidemiological characteristics of sarcoidosis are known to differ between Japanese and Westerners. Therefore, the relationship between cigarette smoking and sarcoidosis in a Japanese population was investigated. METHODS: Three hundred eighty-eight patients newly diagnosed with sarcoidosis between 2000 and 2008 were retrospectively identified. The results of two large surveys of smoking prevalence in Japan provided reference data. Specific clinical manifestations of sarcoidosis were compared between current smokers and never-smokers, after excluding former smokers. RESULTS: The prevalence of current smokers at the time of the diagnosis of sarcoidosis was 59.6% in men and 27.9% in women. With the exception of men in their 30s, the prevalence was higher in all age groups compared with the general Japanese population. The prevalence of lung parenchymal involvement tended to be higher in current smokers than in never-smokers (odds ratio = 1.33 (0.99-1.77), P = 0.054). CONCLUSIONS: This retrospective cohort study suggests that smoking prevalence is higher in Japanese sarcoidosis patients than that reported in Western sarcoidosis patients and that there could be different relationships between smoking and the development of sarcoidosis in these populations.

Serum KL-6 concentrations are associated with molecular sizes and efflux behavior of KL-6/MUC1 in healthy subjects.

BACKGROUND: Serum KL-6, a sialylated sugar chain on human MUC1, is used as a marker of interstitial lung diseases. We recently reported that efflux behavior of KL-6/MUC1 from the alveoli into the bloodstream assessed by molecular analysis differed according to genetically determined molecular sizes and influenced serum KL-6 concentrations in sarcoidosis. This study was designed to investigate associations between molecular size and efflux behavior of KL-6/MUC1, and factors contributing to serum KL-6 concentrations in healthy subjects. METHODS: Western blot analysis using anti-KL-6 antibody was performed on serum obtained from 250 healthy subjects. RESULTS: The efflux behavior of KL-6/MUC1 differed according to the genetically determined molecular sizes in healthy subjects. In subjects having low molecular size, there were significant associations between smoking status, aging, renal function and serum KL-6 concentrations. However, these associations were not significant in the subjects having higher molecular size and the efflux behavior of high molecular size was the only significant determinant of serum KL-6 concentrations. CONCLUSIONS: This study showed an association between KL-6/MUC1 efflux based on molecular size and serum KL-6 concentrations in healthy subjects. We propose that the molecular size and efflux behavior of KL-6/MUC1 should be considered when interpreting serum KL-6 concentrations.