Familial interstitial pneumonia in an adolescent boy with surfactant protein C gene (Y104H) mutation

Recent studies have suggested that some cases of familial interstitial pneumonia are associated with mutations in the gene encoding surfactant protein C (SFTPC). We report here a case of familial interstitial pneumonia in an adolescent boy whose paternal grandfather and father suffered from idiopathic interstitial pneumonia (IIP). The patient was asymptomatic but showed an abnormal shadow in the chest at his medical check-up. The surgical biopsy of the patient revealed non-specific interstitial pneumonia and showed pathological findings similar to those in his father's autopsy. Genomic DNA from blood leucocytes of the patient was sequenced for the Thy104His (Y104H) SFTPC mutation. Based on these results, he was diagnosed with SFTPC mutation-associated familial interstitial pneumonia. There has been no clinical, physiologic and radiologic progression for 4 years since the diagnosis. The relation between clinical manifestation and the mutation site of the patient may broaden the spectrum of SFTPC mutation-associated interstitial pneumonia.

Granuloma-forming interstitial pneumonia occurring one year after the start of everolimus therapy

We experienced a case of interstitial lung disease (ILD) that occurred one year after the start of everolimus therapy for renal cell carcinoma. The pathological features included interstitial pneumonia with granuloma formation. Everolimus is known to cause ILD; however, its pathology is unclear. Granuloma-forming interstitial pneumonia associated with everolimus is uncommon, although it may be one of the pathological patterns associated with everolimus-induced ILD. This is a slow-onset case of everolimus-induced ILD in a patient with renal cell carcinoma. Physicians should thus be aware of the potential for the development of ILD at any time during the administration of everolimus therapy.

Efficacy of inhaled N-acetylcysteine monotherapy in patients with early stage idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

Idiopathic pulmonary fibrosis (IPF) is a fatal disorder for which there are currently no specific or effective medical treatments. A multicentre, prospective, randomized, controlled clinical trial was conducted to assess the efficacy of inhaled N-acetylcysteine (NAC) monotherapy in Japanese patients with early stage IPF.

METHODS

Eligible patients had well-defined IPF of mild-to-moderate severity, with no desaturation on exercise. Of 100 patients screened, 76 were randomly assigned to an NAC treatment group (group A; n = 38) that received 352.4 mg of NAC by inhalation twice daily or to a control group (group B; n = 38) that received no therapy. The primary endpoint was the change from baseline in forced vital capacity (FVC) at 48 weeks.

RESULTS

There were no significant overall differences in the change in FVC between groups A and B. Post hoc exploratory analyses showed that NAC therapy was associated with stability of FVC in (i) a subset of patients with initial FVC <95% of predicted (n = 49; difference in FVC decline 0.12 L; P = 0.02) and (ii) in patients with initial diffusing capacity of carbon monoxide <55% of predicted (n = 21; difference in FVC decline 0.17 L; P = 0.009).

CONCLUSIONS

These findings indicate that NAC monotherapy may have some beneficial effect in patients with early stage IPF. Further trials in more select IPF populations with progressive disease are required to prove the efficacy of inhaled NAC.

α1,6-Fucosyltransferase (Fut8) is implicated in vulnerability to elastase-induced emphysema in mice and a possible non-invasive predictive marker for disease progression and exacerbations in chronic obstructive pulmonary disease (COPD)

Fut8 (α1,6-Fucosyltransferase) heterozygous knock-out (Fut8(+/-)) mice had an increased influx of inflammatory cells into the lungs, and this was associated with an up-regulation of matrix metalloproteinases, MMP-2 and MMP-9, after treatment with porcine pancreatic elastase (PPE), exhibiting an emphysema-prone phenotype as compared with wild type mice (Fut8(+/+)). The present data as well as our previous data on cigarette-smoke-induced emphysema [8] led us to hypothesize that reduced Fut8 levels leads to COPD with increased inflammatory response in humans and is associated with disease progression. To test this hypothesis, symptomatic current or ex-smokers with stable COPD or at risk outpatients were recruited. We investigated the association between serum Fut8 activity and disease severity, including the extent of emphysema (percentage of low-attenuation area; LAA%), airflow limitation, and the annual rate of decline in forced expiratory volume in 1 s (FEV(1)). Association with the exacerbation of COPD was also evaluated over a 3-year period. Serum Fut8 and MMP-9 activity were measured. Fut8 activity significantly increased with age among the at risk patients. In the case of COPD patients, however, the association was not clearly observed. A faster annual decline of FEV(1) was significantly associated with lower Fut8 activity. Patients with lower Fut8 activity experienced exacerbations more frequently. These data suggest that reduced Fut8 activity is associated with the progression of COPD and serum Fut8 activity is a non-invasive predictive biomarker candidate for progression and exacerbation of COPD.

Superiority of PC-SOD to other anti-COPD drugs for elastase-induced emphysema and alteration in lung mechanics and respiratory function in mice

Bronchodilators (such as ipratropium bromide), steroids (such as fluticasone propionate), and newly developed anti-inflammatory drugs (such as roflumilast) are used for patients with chronic obstructive pulmonary disease (COPD). We recently reported that lecithinized superoxide dismutase (PC-SOD) confers a protective effect in mouse models of COPD. We here examined the therapeutic effect of the combined administration of PC-SOD with ipratropium bromide on pulmonary emphysema and compared the effect of PC-SOD to other types of drugs. The severity of emphysema in mice was assessed by various criteria. Lung mechanics (elastance) and respiratory function (ratio of forced expiratory volume in the first 0.05 s to forced vital capacity) were assessed. Administration of PC-SOD by inhalation suppressed elastase-induced pulmonary emphysema, alteration of lung mechanics, and respiratory dysfunction. The concomitant intratracheal administration of ipratropium bromide did not alter the ameliorating effects of PC-SOD. Administration of ipratropium bromide, fluticasone propionate, or roflumilast alone did not suppress the elastase-induced increase in the pulmonary level of superoxide anion, pulmonary inflammatory response, pulmonary emphysema, alteration of lung mechanics, or respiratory dysfunction as effectively as did PC-SOD. PC-SOD, but not the other drugs, showed a therapeutic effect even when the drug was administered after the development of emphysema. PC-SOD also suppressed the cigarette smoke-induced pulmonary inflammatory response and increase in airway resistance. Based on these results, we consider that the inhalation of PC-SOD would be therapeutically beneficial for COPD.

Historical changes in epidemiology of diffuse panbronchiolitis

BACKGROUND AND OBJECTIVE

Japanese pulmonologists, experienced in treating patients with diffuse panbronchiolitis (DPB) prior to the 1980s, have uniformly observed that new incidences of DPB are now a rare event in Japan. However, there is no epidemiological data to support this observation. We examined epidemiological trends of the number of patients with DPB in a large company.

DESIGN

The computerized health records of JR East Company employees were used to identify patients with DPB and then these were followed up using the assessments of these patients in JR Tokyo General Hospital and two other JR hospitals. The whole study period was 27 years (1976-2003), although detailed analyses were carried out for three specific periods; the first was 1976-1980, the second was 1989-1993, and the third was 1999-2003.

RESULTS

In the first period, 11 DPB cases (four incidence, and seven prevalence) were detected among a total of 355,572 workers. In the second period, three DPB cases (one incidence, and two prevalence) were identified from a total of 180,359 workers. In the third period, no case was found in a total of 144,485 workers.

CONCLUSION

This epidemiological trend suggests that both the incidence and prevalence of DPB may have decreased.

IgM-type GM-CSF autoantibody is etiologically a bystander but associated with IgG-type autoantibody production in autoimmune pulmonary alveolar proteinosis

The granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibody (GMAb) is the causative agent underlying autoimmune pulmonary alveolar proteinosis (aPAP). It consists primarily of the IgG isotype. At present, information on other isotypes of the autoantibody is limited. We detected serum the IgM isotype of GMAb (IgM-GMAb) in more than 80% of patients with aPAP and 22% of healthy subjects, suggesting that a continuous antigen pressure may be present in most patients. Levels of the IgM isotype were weakly correlated with IgG-GMAb levels but not IgA-GMAb, suggesting that its production may be associated with that of IgG-GMAb. The mean binding avidity to GM-CSF of the IgM isotype was 100-fold lower than the IgG-GMAb isotype, whereas the IC(50) value for neutralizing capacity was 20,000-fold higher than that of IgG-GMAb, indicating that IgM-GMAb is only a very weak neutralizer of GM-CSF. In bronchoalveolar lavage fluid from nine patients, IgG-GMAb was consistently detected, but IgM-GMAb was under the detection limit in most patients, confirming that IgM-GMAb is functionally a bystander in the pathogenesis of aPAP. It rather may be involved in the mechanism for development of IgG-GMAb in vivo.

Pirfenidone treatment of idiopathic pulmonary fibrosis

Pirfenidone is the first antifibrotic agent to be approved for the treatment of pulmonary fibrosis. Idiopathic pulmonary fibrosis (IPF) is one of the idiopathic interstitial pneumonias with the worst prognoses; approximately half of patients die within 3–5 years, and the need for an effective treatment has been unmet until recently. The etiology of IPF is still unknown and its pathogenesis is poorly understood. Anti-inflammatory drugs, such as corticosteroids and some immunosuppressants, have been empirically used to treat IPF, although they have not been objectively proven to be effective by large-scale randomized, controlled trials. Pirfenidone is an agent that can inhibit the decline of forced vital capacity (FVC)/vital capacity (VC) and that thereby can be hoped to decrease the mortality rate. The number of clinical trials of pirfenidone completed, ongoing, or planned is growing, and the present status of pirfenidone as treatment for IPF is summarized in this review.

Upper gastrointestinal sarcoidosis: report of three cases

Involvement of the upper gastrointestinal tract in sarcoidosis is rare, and an optimal treatment regimen remains to be determined. Here, we report 3 cases of upper gastrointestinal sarcoidosis in Japanese patients aged 57-70 years with or without epigastric symptoms and describe the clinical features, laboratory data, and upper endoscopy and pathological findings. Upper gastrointestinal sarcoidosis was diagnosed based on the presence of noncaseating epithelioid cell granuloma in the lamina propria in the stomach or duodenum. In conclusion, the possibility of upper gastrointestinal sarcoidosis should be considered in patients with epigastric symptoms and a history of sarcoidosis, even in those with stable disease.

Differential association between HLA and diffuse panbronchiolitis in Northern and Southern Chinese

BACKGROUND

Diffuse panbronchiolitis (DPB) is a progressive inflammatory pulmonary disease that predominately affects East Asians. Genetic susceptibility to DPB is correlated with the human leukocyte antigens HLA-B54 in Japanese and HLA-A11 in Koreans. However, no systematic genetic study of DPB pathogenesis has been conducted in the Chinese population. The aim of this study was to investigate the possible association between HLA and disease susceptibility in Chinese patients with DPB.

METHODS

A literature review of both Chinese and English language studies on Chinese DPB patients, published between 1983 and 2010, was conducted. Seventy subjects met the inclusion criteria and were retrospectively analyzed for HLA gene frequency according to geographic region.

RESULTS

HLA-B54 frequency was significantly greater in DPB patients than in controls in the Northern Chinese group (35.7% vs. 4.6%, p=7.5×10(-7)). Although the HLA-B54 frequency was slightly increased in the Southern Chinese patients, the difference was not significant compared with control subjects (14.3% vs. 5.7%, p=0.28). The HLA-A11 frequency was significantly greater in DPB patients than controls in the Southern Chinese group (54.8% vs. 26.4%, p=0.009). Despite an increase of HLA-A11 frequency in the Northern Chinese group, no significant variation in HLA-A11 frequency was found compared with control subjects (42.9% vs. 30.8%, p=0.535). The HLA-A2 frequency was significantly decreased in DPB patients than in controls in the Southern Chinese group (22.9% vs. 66.0%, p=0.001). However, no significant difference in HLA-A2 frequency was found in the Northern Chinese group (50.0% vs. 46.9%, p=0.872).

CONCLUSION

HLA-B54 and HLA-A11 were positively associated with DPB in Northern and Southern Chinese, respectively. Population substructure may impact the genetic predisposition of DPB in China.

Polymyxin B-immobilized fiber column (PMX) treatment for idiopathic pulmonary fibrosis with acute exacerbation: a multicenter retrospective analysis

OBJECTIVE

The prognosis of idiopathic pulmonary fibrosis (IPF) patients with acute exacerbation (AE) is reported to be extremely poor. Several clinical studies suggest that direct hemoperfusion with polymyxin B-immobilized fiber (PMX) may have beneficial effects on AE in patients with interstitial pneumonia (IP). The aim of this multicenter retrospective analysis was to investigate whether PMX treatment could provide improvement of oxygenation and survival benefits in IPF patients with AE.

METHODS

We conducted a retrospective study of 160 IP patients (including 73 IPF) with AE treated by PMX at 18 institutions in Japan. PMX treatment was carried out twice. The total hemoperfusion time of PMX treatment was, on average, 12 hours. Data concerning oxygenation on PMX treatment and survival after AE were collected and analyzed.

RESULTS

In IPF patients with AE, arterial oxygen tension (PaO(2))/inspiratory oxygen fraction (FiO(2)), (P/F) ratio was significantly improved at the end of the 2nd treatment with PMX (173.9 ± 105.4 to 195.2 ± 106.8 Torr, p=0.003). White blood cell count was significantly reduced at the end of the 2nd treatment (13,330 ± 7,002 to 9,426 ± 5,188 /mm(3), p<0.001). These clinical changes were also observed on analysis of all 160 IP patients with AE. The one- and three-month survival rates of IPF patients after AE were 70.1% and 34.4%, respectively.

CONCLUSION

PMX treatment may improve oxygenation and survival in IPF patients with AE. Prospective, controlled trials of PMX treatment for IPF with AE are warranted to verify this potential benefit.

Staphylococcal enterotoxin B toxic shock syndrome induced by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA)

We herein report a case of toxic shock syndrome (TSS) associated with the 2009 pandemic H1N1 (pH1N1) influenza virus and a community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection in a 16-year-old Vietnamese girl. Staphylococcal enterotoxin B (SEB) was detected in the patient's serum, and the level of anti-SEB antibodies was found to be elevated. A flow cytometric analysis showed evidence of activated SEB-reactive Vβ3+ and Vβ12+ T cells. These data suggest that the CA-MRSA-induced activation of SEB-reactive T cells may cause TSS in patients with pH1N1 virus infection. Moreover, this is the first report describing immunological confirmation of SEB contributing directly to TSS in a patient fulfilling the diagnostic criteria of TSS.

Suppression of expression of heat shock protein 70 by gefitinib and its contribution to pulmonary fibrosis

Drug-induced interstitial lung disease (ILD), particularly pulmonary fibrosis, is of serious clinical concern. Gefitinib, a tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR), is beneficial as a drug for treating non-small cell lung cancer; however, this drug induces ILD and the molecular mechanisms underpinning this condition remain unclear. We recently reported that expression of heat shock protein 70 (HSP70) protects against bleomycin-induced pulmonary fibrosis, an animal model of pulmonary fibrosis. In this study, we have examined the effects of drugs known to induce ILD clinically on the expression of HSP70 in cultured lung epithelial cells and have found that gefitinib has a suppressive effect. Results of a luciferase reporter assay, pulse-labelling analysis of protein and experiments using an inhibitor of translation or transcription suggest that gefitinib suppresses the expression of HSP70 at the level of translation. Furthermore, the results of experiments with siRNA for Dicer1, an enzyme responsible for synthesis of microRNA, and real-time RT-PCR analysis suggest that some microRNAs are involved in the gefitinib-induced translational inhibition of HSP70. Mutations in the EGFR affect the concentration of gefitinib required for suppressing the expression of HSP70. These results suggest that gefitinib suppresses the translation of HSP70 through an EGFR- and microRNA-mediated mechanism. In vivo, while oral administration of gefitinib suppressed the pulmonary expression of HSP70 and exacerbated bleomycin-induced pulmonary fibrosis in wild-type mice, these effects were not as distinct in transgenic mice expressing HSP70. Furthermore, oral co-administration of geranylgeranylacetone (GGA), an inducer of HSP70, suppressed gefitinib-induced exacerbation of bleomycin-induced pulmonary fibrosis. Taken together, these findings suggest that gefitinib-induced exacerbation of bleomycin-induced pulmonary fibrosis is mediated by suppression of pulmonary expression of HSP70 and that an inducer of HSP70 expression, such as GGA, may be therapeutically beneficial for the treatment of gefitinib-induced pulmonary fibrosis.

Exploratory analysis of a phase III trial of pirfenidone identifies a subpopulation of patients with idiopathic pulmonary fibrosis as benefiting from treatment

BACKGROUND

A phase III trial in Japan showed that pirfenidone is effective for idiopathic pulmonary fibrosis (IPF). To find out which patients specifically benefit from pirfenidone, we analyzed in an exploratory manner the data from the phase III trial.

METHODS

The patients in the phase III trial were stratified by baseline percentage predicted vital capacity (%VC), arterial oxygen partial pressure (PaO(2)), and the lowest oxygen saturation by pulse oximetry (SpO(2)) during the 6-minute steady-state exercise test (6MET). In the subpopulations, changes in VC and subjective symptoms (cough and dyspnea on the Fletcher, Hugh-Jones [F, H-J] Classification scale) were evaluated in patients treated with high-dose (1800 mg/day) pirfenidone, low-dose (1200 mg/day) pirfenidone, and placebo at week 52.

RESULTS

Significant efficacy of pirfenidone in reducing the decline in VC could be seen in a subpopulation having %VC ≥ 70% and SpO(2) < 90% at baseline. This favorable effect was accompanied by categorical change in VC and progression-free survival time. In the subpopulation, pirfenidone significantly suppressed cough and dyspnea.

CONCLUSIONS

IPF patients having %VC ≥ 70% and SpO(2) < 90% at baseline will most likely benefit from pirfenidone when evaluated using changes in VC (and %VC), and cough and dyspnea symptoms. This subpopulation could expect to benefit most from pirfenidone treatment.

TRIAL REGISTRATION

This clinical trial was registered with the Japan Pharmaceutical Information Center (JAPIC) on September 13th, 2005 (REGISTRATION NUMBER: JAPICCTI-050121).

Reduction in serum high mobility group box-1 level by polymyxin B-immobilized fiber column in patients with idiopathic pulmonary fibrosis with acute exacerbation

BACKGROUND/AIM

Recent reports suggest that polymyxin B (PMX)-immobilized fiber may have beneficial effects in idiopathic pulmonary fibrosis (IPF) with acute exacerbation (AE). High mobility group box-1 (HMGB-1) is an important pro-inflammatory mediator that contributes to acute lung inflammation. This study was aimed to investigate whether PMX treatment affects serum HMGB-1 levels and oxygenation in IPF patients with AE.

MATERIALS AND METHODS

Twenty IPF patients with AE were treated by PMX. PMX treatment was carried out once daily for 2 successive days. Serum HMGB-1 levels were measured before and after PMX treatment. We also monitored arterial oxygen tension (PaO(2))/inspiratory oxygen fraction (FiO(2)) (P/F) ratio. PMX fiber columns were analyzed to examine whether HMGB-1 was absorbed by PMX.

RESULTS

PMX treatment significantly improved both the serum HMGB-1 level and P/F ratio. HMGB-1 was detected in washing medium from the PMX column.

CONCLUSION

PMX treatment may reduce serum HMGB-1 and improve oxygenation in patients with IPF with AE.

The clinical significance of 5% change in vital capacity in patients with idiopathic pulmonary fibrosis: extended analysis of the pirfenidone trial

BACKGROUND

Our phase III clinical trial of pirfenidone for patients with idiopathic pulmonary fibrosis (IPF) revealed the efficacy in reducing the decline of vital capacity (VC) and increasing the progression-free survival (PFS) time by pirfenidone. Recently, marginal decline in forced VC (FVC) has been reported to be associated with poor outcome in IPF. We sought to evaluate the efficacy of pirfenidone from the aspects of 5% change in VC.

METHODS

Improvement ratings based on 5% change in absolute VC, i.e., "improved (VC ≥ 5% increase)", "stable (VC < 5% change)", and "worsened (VC ≥ 5% decrease)" at month 3, 6, 9 and 12 were compared between high-dose pirfenidone (1800 mg/day; n = 108) and placebo (n = 104) groups, and (high-dose and low-dose (1200 mg/day; n = 55)) pirfenidone (n = 163) and placebo groups. PFS times with defining the disease progression as death or a ≥ 5% decline in VC were also compared between high-dose pirfenidone and placebo groups, and low-dose pirfenidone and placebo groups. Furthermore, considering "worsened" and "non-worsened (improved and stable)" of the ratings at months 3 and 12 as "positive" and "negative", respectively, and the positive and negative predictive values of the ratings were calculated in each group.

RESULTS

In the comparison of the improvement ratings, the statistically significant differences were clearly revealed at months 3, 6, 9, and 12 between pirfenidone and placebo groups. Risk reductions by pirfenidone to placebo were approximately 35% over the study period. In the comparison of the PFS times, statistically significant difference was also observed between pirfenidone and placebo groups. The positive/negative predictive values in placebo and pirfenidone groups were 86.1%/50.8% and 87.1%/71.7%, respectively. Further, the baseline characteristics of patients worsened at month 3 had generally severe impairment, and their clinical outcomes including mortality were also significantly worsened after 1 year.

CONCLUSIONS

The efficacy of pirfenidone in Japanese phase III trial was supported by the rating of 5% decline in VC, and the VC changes at month 3 may be used as a prognostic factor of IPF.

TRIAL REGISTRATION

This clinical trial was registered with the Japan Pharmaceutical Information Center (JAPIC) on September 13th, 2005 (REGISTRATION NUMBER: JAPICCTI-050121).

Therapeutic effect of lecithinized superoxide dismutase on pulmonary emphysema

No medication exists that clearly improves the mortality of chronic obstructive pulmonary disease (COPD). Oxidative molecules, in particular superoxide anions, play important roles in the COPD-associated abnormal inflammatory response and pulmonary emphysema, which arises because of an imbalance in proteases and antiproteases and increased apoptosis. Superoxide dismutase (SOD) catalyzes the dismutation of superoxide anions. Lecithinized human Cu/Zn- SOD (PC-SOD) has overcome a number of the clinical limitations of SOD, including low tissue affinity and low stability in plasma. In this study, we examine the effect of PC-SOD on elastase-induced pulmonary emphysema, an animal model of COPD. The severity of the pulmonary inflammatory response and emphysema in mice was assessed by various criteria, such as the number of leukocytes in the bronchoalveolar lavage fluid and the enlargement of airspace. Not only intravenous administration but also inhalation of PC-SOD suppressed elastase-induced pulmonary inflammation, emphysema, and dysfunction. Inhalation of PC-SOD suppressed the elastase-induced increase in the pulmonary level of superoxide anions and apoptosis. Inhalation of PC-SOD also suppressed elastase-induced activation of proteases and decreased in the level of antiproteases and expression of proinflammatory cytokines and chemokines. We also found that inhalation of PC-SOD suppressed cigarette smoke-induced pulmonary inflammation. The results suggest that PC-SOD protects against pulmonary emphysema by decreasing the pulmonary level of superoxide anions, resulting in the inhibition of inflammation and apoptosis and amelioration of the protease/antiprotease imbalance. We propose that inhalation of PC-SOD would be therapeutically beneficial for COPD.

Molecular cloning of two novel mucin-like genes in the disease-susceptibility locus for diffuse panbronchiolitis

Diffuse panbronchiolitis (DPB) is a rare complex genetic disease affecting East Asians and is strongly associated with the class I human leukocyte antigens (HLA)-B54 in Japanese and HLA-A11 in Koreans. We recently showed that an HLA-associated major susceptibility gene for DPB is probably located within the 200 kb in the class I region 300 kb telomeric of the HLA-B locus on the chromosome 6p21.3. We cloned two novel mucin-like genes designated panbronchiolitis related mucin-like 1 and 2 (PBMUCL1 and PBMUCL2) in the candidate region, which form a mucin-like gene cluster together with two adjacent genes, MUC21 and DPCR1. PBMUCL1 gene expression was remarkably upregulated by polyinosine-polycytidylic acid [poly(I:C)] stimulation in normal human bronchial epithelial cells redifferentiated at the air-liquid interface. We found genetic polymorphisms in PBMUCL1 gene which were associated with DPB: the A-allele of the PBMUCL1 intron 2 single nucleotide polymorphism (SNP) was positively associated and variable numbers of tandem repeats (VNTR) polymorphism in exon 3 (1,890-base pair deletion) was negatively associated. Despite a strong association with HLA-B in the Japanese, the mucin-like gene PBMUCL1 is also one of the candidate genes of DPB susceptibility.