KL-6, a human MUC1 mucin, is chemotactic for human fibroblasts

TNF-α is a key regulator of MUC1, an anti-inflammatory molecule, during airway Pseudomonas aeruginosa infection

Muc1 is a heterodimeric mucin that is expressed on the apical surface of airway epithelial cells as well as hematopoietic cells. Both in vivo and in vitro studies revealed that Muc1 suppresses inflammatory responses induced by Pseudomonas aeruginosa (PA). In this study, we sought to determine, using intact animals (C57BL/6 mice), whether the expression of Muc1 is important during airway PA infection, and how Muc1 levels are controlled during inflammation. Our results showed that: (1) Muc1 levels in the wild-type (WT) mice were initially low, but gradually increased after PA inhalation, reaching a peak on Day 2, remaining elevated until Day 4, and then gradually decreasing to basal levels on Day 7; (2) TNF receptor 1(-/-) mice failed to increase Muc1 levels after PA infection; (3) after PA inhalation, more inflammatory cells were present in the bronchoalveolar lavage fluid from either Muc1(-/-) or TNF receptor(-/-) mice compared with their WT control animals; (4) more apoptotic neutrophils were present in bronchoalveolar lavage fluid from WT mice compared with Muc1(-/-) mice. We conclude that Muc1(-/-) mice are more inflammatory than WT mice during airway PA infection as a result of both an increase in neutrophil influx and a decrease in neutrophil apoptosis. These results suggest that the up-regulation of Muc1 during airway PA infection might be crucial for suppressing excessive and prolonged inflammatory responses, and is induced mainly by TNF-α, the key proinflammatory mediator.

Serum KL-6 levels as a biomarker of lung injury in respiratory syncytial virus bronchiolitis

To evaluate whether KL-6 concentration is a useful biomarker of the severity of respiratory syncytial virus (RSV) bronchiolitis, we determined KL-6 concentrations in patients with RSV bronchiolitis with or without chronic heart disease (CHD). We enrolled 52 patients who had been diagnosed with RSV bronchiolitis and required admission to the hospital at the Department of Pediatrics of Fukushima Medical University School of Medicine from 2004 to 2005. These patients were divided into two groups: Group 1 consisted of patients without any underlying disease, and Group 2 consisted of patients with CHD. These patients were assigned to three categories. Stage A consisted of patients without oxygen dosage, stage B of patients who required oxygen dosage, and stage C of patients required artificial respiration. We evaluated baseline characteristics, clinical features, and serum KL-6 concentration in Group 1, Group 2, and a control group (healthy infants without infection). Mean serum KL-6 concentrations in patients with RSV bronchiolitis were higher than those in the control group (471.8 +/- 236.9 and 127.1 +/- 69.1 U/ml, respectively). Mean serum KL-6 concentration was higher in Group 2 than in Group 1 (692.8 +/- 313.1 and 390.4 +/- 132.7 U/ml, respectively). Mean serum KL-6 concentrations were higher in stage C than in stages A and B, and mean serum KL-6 concentrations were higher in stage B than in stage A. These findings suggest that serum KL-6 is associated with the severity of RSV bronchiolitis and that it may be a useful biomarker for the severity of RSV bronchiolitis.

Expression of KL-6 mucin, a human MUC1 mucin, in intrahepatic cholangiocarcinoma and its potential involvement in tumor cell adhesion and invasion

AIMS

Aberrant expressions of KL-6 mucin were proved to be associated with worse tumor behaviors of many carcinomas. This study was to evaluate the expression KL-6 mucin, a human MUC1 mucin, in intrahepatic cholangiocarcinoma (CC) and its significance in tumor progression.

MAIN METHODS

KL-6 mucin expressions in 21 patients with CC, 12 with combined hepatocellular and cholangiocarcinoma (cHCC-CC), and 78 with hepatocellular carcinoma (HCC) were detected by immunohistochemical staining. The effects of two glycosylation inhibitors (tunicamycin and benzyl-alpha-N-acetylgalactosamine (BAG)) on CC cell proliferations were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assays. KL-6 mucin expressions were detected by immunocytochemical staining and western blotting after tunicamycin or BAG treatment. Cell adhesive and invasive properties were evaluated by adhesion tests and transwell chamber assays after tunicamycin or BAG treatment.

KEY FINDINGS

Positive KL-6 mucin staining was observed in all CC tissues and CC areas of cHCC-CC tissues. Immunocytochemical staining and western blotting showed that KL-6 mucin expressions were significantly reduced after both inhibitors treatment. Cell adhesive properties were significantly decreased after both inhibitors treatment, while cell invasive abilities were significantly decreased after BAG but not tunicamycin treatment.

SIGNIFICANCE

This study indicated that KL-6 mucin might be a specific tumor target for CC. Therapeutic strategies that target glycosylation of KL-6 mucin may be useful to control aggressive behaviors of CC.

Serum markers in interstitial pneumonia with and without Pneumocystis jirovecii colonization: a prospective study

Background

In patients with chronic respiratory disease, Pneumocystis jirovecii (P. jirovecii) colonization is observed, and may influence disease progression and systemic inflammation. Pneumocystis pneumonia causes interstitial changes, so making a diagnosis of PCP in patients who have interstitial pneumonia (IP) with P. jirovecii colonization is sometimes difficult based on radiography.

Methods

This study investigated the prevalence of P. jirovecii colonization in IP patients and assessed pulmonary injury due to P. jirovecii colonization by measurement of serum markers (KL-6, SP-A, SP-D, and (1→3) β-D-glucan (β-D-glucan)) and the peripheral lymphocyte counts, prospectively. A total of 75 patients with idiopathic pulmonary fibrosis (n = 29), collagen vascular-related interstitial pneumonia (n = 19), chronic bronchitis or pneumonia (n = 20), and Pneumocystis pneumonia (n = 7) were enrolled in this prospective study. P. jirovecii DNA was detected in sputum samples, while serum markers and the lymphocyte count were measured in the peripheral blood.

Results

IP patients (idiopathic pulmonary fibrosis and collagen vascular-related IP) who received oral corticosteroids had a high prevalence of P. jirovecii colonization (23.3%). In IP patients, oral corticosteroid therapy was a significant risk factor for P. jirovecii colonization (P < 0.05). Serum markers did not show differences between IP patients with and without P. jirovecii colonization. The β-D-glucan level and lymphocyte count differed between patients with Pneumocystis pneumonia or P. jirovecii colonization.

Conclusion

Serum levels of KL-6, SP-A, SP-D, and β-D-glucan were not useful for detecting P. jirovecii colonization in IP patients. However, the serum β-D-glucan level and lymphocyte count were useful for distinguishing P. jirovecii colonization from pneumocystis pneumonia in IP patients.

The pathogenetic and prognostic value of biologic markers in acute lung injury

Over the past 2 decades, measurement of biomarkers in both the airspaces and plasma early in the course of acute lung injury has provided new insights into the mechanisms of lung injury. In addition, biologic markers of cell-specific injury, acute inflammation, and altered coagulation correlate with mortality from acute lung injury in several single center studies as well as in multicenter clinical trials. To date, biomarkers have been measured largely for research purposes. However, with improved understanding of their role in the pathogenesis of acute lung injury, biomarkers may play an important role in early detection of lung injury, risk stratification for clinical trials, and, ultimately, tailoring specific therapies to individual patients. This article provides a review of biologic markers in acute lung injury, with an emphasis on recent analysis of results from multicenter clinical trials.

Usefulness of monitoring the circulating Krebs von den Lungen-6 levels to predict the clinical outcome of patients with advanced nonsmall cell lung cancer treated with epidermal growth factor receptor tyrosine kinase inhibitors

Krebs von den Lungen-6 (KL-6) is a high molecular weight glycoprotein classified in the category of human MUC1 mucin. KL-6 has been reported to serve as a sensitive marker for interstitial pneumonia; however, recent studies have suggested that it can also be used as a tumor marker as its origin shows. To further elucidate the clinicopathological significance of circulating KL-6 in lung cancer, we monitored the circulating KL-6 levels in advanced nonsmall cell lung cancer (NSCLC) patients and analyzed the association between these levels and the clinical outcome of EGFR-TKI treatment. The pretreatment levels of circulating KL-6 were found to be significantly higher in progressive disease (PD) patients than disease-controlled (partial response (PR) and stable disease (SD)) patients. Multivariate analyses revealed the circulating KL-6 level to be an independent prognostic factor for overall survival as well as progression-free survival. In addition to these observations, we found that changes in circulating KL-6 levels at 2 weeks after the start of EGFR-TKI treatment from the baseline could quite precisely discriminate PD cases from PR or SD patients and the clinical outcome of EGFR-TKI in NSCLC patients. These results indicate that the monitoring of circulating KL-6 levels in NSCLC patients is effective for both selecting patients to be treated with EGFR-TKI and predicting the clinical outcome of EGFR-TKI. In addition, the findings suggest that the circulating KL-6 level could be used as a clinically relevant biomarker in patients with NSCLC, particularly those who are candidates for EGFR-TKI treatment.

Elevated serum level of sialylated glycoprotein KL-6 predicts a poor prognosis in patients with non-small cell lung cancer treated with gefitinib

PURPOSE

The factors affecting survival after gefitinib treatment in patients with non-small cell lung cancer (NSCLC) remain to be fully elucidated, although epidermal growth factor receptor (EGFR) mutation is a substantial prognostic factor. KL-6 has been studied as a useful indicator for interstitial lung diseases; however, it was first discovered as a lung cancer-related antigen. The aim of this study was to investigate the prognostic value of the serum KL-6 levels in advanced NSCLC patients treated with gefitinib and thus determine its association with the EGFR mutation status.

PATIENTS AND METHODS

Between September 2002 and September 2005, 41 patients with NSCLC were treated with gefitinib after having their serum KL-6 levels measured at Okayama University Hospital. EGFR mutations were analyzed by direct sequence methods.

RESULTS

The serum KL-6 levels ranged from 199 to 9080U/ml (median, 550U/ml), and 54% of 41 patients showed a level higher than the cut-off level of 500U/ml. The median progression-free survival (PFS) time and the median overall survival (OS) time were 4.7 months and 13.9 months, respectively. Multivariate analyses revealed that the elevated KL-6 level was an independent adverse prognostic factor for PFS (hazard ratio: 2.278, p=0.040) as well as OS (hazard ratio: 4.858, p=0.002) in NSCLC patients treated with gefitinib. The EGFR mutation status was analyzed in 22 patients (54%). Among those with wild-type EGFR, the patients with high serum KL-6 levels also had a worse survival than those within normal serum KL-6 levels (6.5 months versus 13.3 months, p=0.0194).

CONCLUSION

Our data suggest that NSCLC patients with high serum KL-6 levels tended to have a poor clinical outcome when treated with gefitinib.

Serum KL-6 level is elevated in chronic hepatitis C patients with combination therapy of pegylated interferon and ribavirin

OBJECTIVES

The aim of this study was to evaluate whether or not combination therapy of pegylated interferon (IFN) and ribavirin for chronic hepatitis (CH) C patients enhances the serum level of KL-6, a sensitive marker for interstitial pneumonia.

METHODS

CH C patients proven histologically and treated with combination therapy of pegylated IFN-alpha-2b and ribavirin, IFN monotherapy or untreated for 48 weeks were retrospectively selected in chronological order in groups of 25. Serum levels of KL-6 were measured by enzyme-linked immunosorbent assay by use of serum stored at -80 degrees C before and at 12, 24, 36, 48 weeks after the initiation of treatment or follow up.

RESULTS

The average serum KL-6 levels in patients treated with combination therapy of pegylated IFN and ribavirin increased by 21% at 12 weeks after the start, 23% at 24 weeks, and 28% at 48 weeks. In patients treated with combination therapy of pegylated IFN and ribavirin, the serum KL-6 level significantly increased during treatment. Patients achieved an elevated serum KL-6 level of more than 450 U/ml with statistical significance when: 1) combination therapy was given (P=0.011), 2) serum KL-6 level pretreatment was high more than 300 U/ml (P=0.014).

CONCLUSION

The present study suggests that onset of interstitial pneumonia should be carefully checked in the combination therapy of pegylated-IFN and ribavirin.

Circulating KL-6/MUC1 mucin carrying sialyl Lewisa oligosaccharide is an independent prognostic factor in patients with lung adenocarcinoma

MUC1 mucin is frequently observed in adenocarcinomas, and its association with metastasis has been postulated through the interaction between sialyl Lewis oligosaccharides present on this glycoprotein and selectins. Levels of soluble MUC1 recognized by anti-KL-6 monoclonal antibody were also frequently elevated in the sera of lung adenocarcinoma patients. The aim of this study was to demonstrate the presence of KL-6/MUC1 carrying sialyl Lewis(a) oligosaccharide, designated as SLAK, and subsequently evaluate the clinical significance of circulating SLAK in patients with lung adenocarcinoma. We developed a sandwich ELISA system using anti-sialyl Lewis(a) and anti-KL-6 antibodies to detect SLAK, and also measured circulating SLAK levels in 97 healthy controls and 103 patients with lung adenocarcinoma. Circulating SLAK levels were measured in the sera taken before treatment and then were evaluated to clarify whether such levels were related to the clinical outcomes. Levels of circulating SLAK were significantly higher in lung adenocarcinoma patients than in healthy subjects, and a higher serum SLAK level was correlated with the presence of distant metastasis. The overall survival rate for patients with high serum SLAK levels was significantly poorer than that of patients with low serum SLAK levels. The survival analysis restricted to the patients with distant metastasis also showed the same trend. In a multivariate survival analysis in lung adenocarcinoma patients, a high serum SLAK level was indicated as an independent prognostic factor. In conclusion, the circulating SLAK level at diagnosis is useful for predicting a poor prognosis in patients with lung adenocarcinoma.

Serum KL-6 as a Marker for Bronchiolitis Obliterans Syndrome after Lung Transplantation

Bronchiolitis obliterans (BO) is the pathologic manifestation of chronic allograft rejection in lung transplant recipients and specific diagnosis requires invasive tests. BO causes progressive obstruction of the small airways. The term bronchiolitis obliterans syndrome (BOS) is a clinical surrogate for the histopathologic diagnosis of BO and is measured by lung function testing. KL-6 is a glycoprotein expressed on pulmonary epithelial cells and it is present in the serum of normal individuals in small amounts. Serum KL-6 has been shown to be a useful marker of disease activity in interstitial lung diseases. We demonstrated that serum levels of KL-6 are elevated in lung transplant recipients with BOS when compared with those without BOS and healthy controls. Our results indicate that serum KL-6 measurement has the potential to serve as a noninvasive diagnostic test for the detection of BO in lung transplant recipients.

Circulating levels of KL-6 in acute respiratory distress syndrome sepsis or traumatic brain injury in critically ill children

KL-6 is a high molecular weight glycoprotein that is expressed on the apical borders of normal secretary alveolar epithelial cells. The aim of our study was to elucidate the potential role of circulating levels of KL-6, related to C-reacting protein (CRP), disease severity (PRISM, TISS), length of stay (LOS) or mechanical ventilation (LOMV), and outcome, in children with acute respiratory distress syndrome (ARDS), sepsis, or traumatic brain injury (TBI). KL-6 concentrations were monitored using solid phase sandwich enzyme-linked immunosorbent assay in plasma of nine patients with ARDS and compared to nine patients with TBI, nine with sepsis, and nine ventilated patients with cancer of matched illness severity on days 1, 3, 5, 7, and 10. Initial respiratory/ventilatory parameters (oxygenation index, plateau pressures) were recorded for ARDS patients. Patients with ARDS had higher early plasma levels of KL-6 (956 +/- 400 U/ml), as compared to patients with TBI (169 +/- 9 U/ml), sepsis (282 +/- 81 U/ml), and ventilated controls (255 +/- 40 U/ml). Significant correlations were demonstrated between plasma KL-6 concentration and oxygenation index, PaO(2): FiO(2) ratio, LOS and LOMV, but not with CRP or PRISM. Only in patients with ARDS, plasma KL-6 levels were higher in non-survivors than survivors (P < 0.03). Plasma KL-6 levels have possible prognostic significance and may provide a useful marker for ARDS in critically ill children.

The Mucin-1 568 Adenosine to Guanine Polymorphism Influences Serum Krebs von den Lungen-6 levels

Krebs von den Lungen (KL)-6 offers a new perspective as a disease marker in pulmonary diseases. The aim of this study was to analyze whether serum KL-6 levels are dependent on the functional adenosine to guanine mucin-1 (MUC1) gene polymorphism at nucleotide position 568 in a well-characterized white population. Polymorphisms were determined in 327 healthy, white individuals and 74 patients with sarcoidosis, using a PCR-sequence-specific primer assay. The serum KL-6 levels were measured by ELISA. Significant differences between serum KL-6 levels of healthy subjects who were grouped according to MUC1 568 genotype were observed (P<0.0001) (mean+/-SEM): AA (195.2+/-9.9 U/ml; 95% confidence interval [CI], 175.7-214.8), AG (246.0+/-8.6 U/ml; 95% CI, 229.0-263.1), and GG (302.6+/-11.8 U/ml; 95%CI, 279.3-326.0). In the patients with sarcoidosis, the results were (mean+/-SD): AA (550.1+/-411.7; 95% CI, 380.2-720.1), AG (716.3+/-452.4; 95% CI, 547.4-885.2), GG (1,151.0+/-1122; 95% CI, 610.1-1692.0); P=0.02. Comparison of the KL-6 levels in which the 568 genotype was ignored rendered 6 out of 74 (7.5%) misclassifications of "elevated" versus "normal" KL-6 levels or vice versa. In conclusion, the MUC1 568 A to G polymorphism may be of interest for diagnostic purposes because our study delivered in vivo evidence that it contributes to interindividual variations in KL-6 levels.

Assessment of KL-6 as a tumor marker in patients with hepatocellular carcinoma

AIM: To investigate the clinical significance of KL-6 as a tumor marker of HCC in two different ethnic groups with chronic liver disease consecutively encountered at outpatient clinics.

METHODS: Serum KL-6 was measured by the sandwich enzyme immunoassay method using the KL-6 antibody (Ab) as both the capture and tracer Ab according to the manufacturer’s instructions (Eisai, Tokyo, Japan). Assessment of alpha fetoprotein (AFP) and protein induced vitamin K deficiency or absence (PIVKA-II) was performed in both groups using commercially available kits.

RESULTS: A significantly higher mean serum KL-6 (556±467 U/L) was found in HCC in comparison with non-HCC groups either with (391±176 U/L; P<0.001) or without (361±161 U/L; P<0.001) liver cirrhosis (LC). Serum KL-6 level did not correlate with either AFP or PIVKA-II serU/Levels. Using receiver operating curve analysis for KL-6 as a predictor for HCC showed that the area under the curve was 0.574 (95%CI = 0.50-0.64) and the KL-6 level that gave the best sensitivity (61%) was found to be 334 U/L but according to the manufacturer’s instructions; a cut-off point of 500 U/L was used that showed the highest specificity (80%) in comparison with AFP and PIVKA-II (78% vs 72% respectively). Combining the values of the three markers improved specificity of AFP for HCC diagnosis from 78% for AFP alone; 93% for AFP plus PIVKA-II to 99% for both plus KL-6 value (P<0.001). Mean serum alkaline phosphatase level was significantly higher in KL-6 positive (564±475) in comparison with KL-6 negative (505±469) HCC patients (P = 0.021), but such a difference was not found among non-HCC corresponding groups.

CONCLUSION: KL-6 is suggested as a tumor for HCC. Its positivity may reflect HCC-associated cholestasis and/or local tumor invasion.

KL-6, a human MUC1 mucin, promotes proliferation and survival of lung fibroblasts

The serum level of KL-6, a MUC1 mucin, is a clinically useful marker for various interstitial lung diseases. Previous studies demonstrated that KL-6 promotes chemotaxis of human fibroblasts. However, the pathophysiological role of KL-6 remains poorly understood. Here, we further investigate the functional aspects of KL-6 in proliferation and apoptosis of lung fibroblasts. KL-6 accelerated the proliferation and inhibited the apoptosis of all human lung fibroblasts examined. An anti-KL-6 monoclonal antibody counteracted both of these effects induced by KL-6 on human lung fibroblasts. The pro-fibroproliferative and anti-apoptotic effects of KL-6 are greater than and additive to those of the maximum effective concentrations of platelet-derived growth factor, basic fibroblast growth factor, and transforming growth factor-beta. These findings indicate that increased levels of KL-6 in the epithelial lining fluid may stimulate fibrotic processes in interstitial lung diseases and raise the possibility of applying an anti-KL-6 antibody to treat interstitial lung diseases.

Usefulness of quantifying serum KL-6 levels in the follow-up of uveitic patients with sarcoidosis

BACKGROUND

KL-6 is a human glycoprotein secreted by type II alveolar cells in the lung, and its serum levels increase in pneumonia of various causes. We previously reported that serum KL-6 levels in uveitis patients with sarcoidosis were significantly higher than those of other uveitis patients and healthy controls. Additionally, the combined measurement of serum KL-6 and angiotensin converting enzyme (ACE) was useful for screening uveitic patients to diagnose sarcoidosis. The purpose of the present study was to investigate the clinical usefulness of quantifying serum KL-6 levels for following-up the patients with sarcoidosis.

METHODS

Sera were obtained from 36 uveitic patients diagnosed with sarcoidosis and the same number of healthy volunteers. To examine the influence of systemic medication, we also collected blood samples from four more sarcoidosis patients, who were systemically treated with corticosteroid or angiotensin converting enzyme (ACE) inhibitor, an anti-hypertensive drug. The serum concentration of KL-6 was measured by a human KL-6 electrochemiluminescence immunoassay (ECLIA).

RESULTS

The mean KL-6 concentrations of sarcoidosis patients and healthy controls were 449.3+/-66.3 (mean+/-SE) and 192.1+/-11.3, respectively. The average levels of serum KL-6 were significantly elevated in sarcoidosis patients compared with healthy control subjects (P<0.001), and there were significant correlations between serum KL-6 and ACE levels in the patients with sarcoidosis (r=0.70 and P<0.0001). Moreover, serum KL-6 concentrations were less affected by systemic corticosteroid, and unaffected by ACE inhibitory drugs in contrast to ACE levels.

CONCLUSIONS

Measurement of serum KL-6 in the uveitic patients may be useful to follow-up the diagnosed sarcoidosis, as well as for diagnosing sarcoidosis, because the serum KL-6 level was well correlated with the ACE level, and less affected by systemic medication than ACE levels.

Serum biomarkers in interstitial lung diseases

The use of biomarkers in medicine lies in their ability to detect disease and support diagnostic and therapeutic decisions. New research and novel understanding of the molecular basis of the disease reveals an abundance of exciting new biomarkers who present a promise for use in the everyday clinical practice. The past fifteen years have seen the emergence of numerous clinical applications of several new molecules as biologic markers in the research field relevant to interstitial lung diseases (translational research). The scope of this review is to summarize the current state of knowledge about serum biomarkers in interstitial lung diseases and their potential value as prognostic and diagnostic tools and present some of the future perspectives and challenges.

Serum KL-6 and Surfactant Proteins A and D in Pediatric Interstitial Lung Disease

OBJECTIVE

To determine if serum KL-6, surfactant protein A (SP-A), and surfactant protein D (SP-D) levels are elevated in pediatric interstitial lung disease (ILD) and associated with pulmonary function and disease severity score.

METHODS

Serum KL-6, SP-A, and SP-D levels were measured by enzyme-linked immunosorbent assay in 10 children with ILD and in 10 healthy volunteers. In the ILD group, FEV1 percentage of predicted, FVC percentage of predicted, and ILD disease severity score were measured and correlated with serum KL-6, SP-A, and SP-D levels.

RESULTS

For the ILD and control groups, respectively, mean serum KL-6 was 4,523 U/mL and 206 U/mL (p = 0.007), mean serum SP-A was 133 ng/mL and 21 ng/mL (p = 0.003), and mean serum SP-D was 304 ng/mL and 75 ng/mL (p = 0.004). There was an inverse relationship between SP-A and FVC (p = 0.05), and between SP-D and FEV1 (p = 0.05). There was a direct relationship between SP-D and ILD score (p = 0.05).

CONCLUSIONS

Serum KL-6, SP-D and SP-D levels are elevated in children with ILD. SP-A and SP-D levels appear to correlate with some measures of disease severity.

Role of KL-6 in evaluating the disease severity of rheumatoid lung disease: comparison with HRCT

OBJECTIVE

To determine the role of KL-6 (Krebs von den Lungen-6) in evaluating the disease severity of pulmonary lesions in rheumatoid arthritis (RA) compared with high resolution computed tomography (HRCT) findings.

METHODS

Fifty serum KL-6 levels and HRCT images were prospectively obtained from 47 RA patients. Eight HRCT findings were classified into five grades. Patients were also divided into two groups according to the KL-6 threshold level and HRCT findings were evaluated.

RESULTS

There was a positive correlation between the serum KL-6 level and the total CT score (r = 0.83). Reticular opacity most closely related to the serum KL-6 levels (r = 0.84). In the high KL-6 group (n = 10), the average CTscore was markedly increased (64.6 points) and severe honeycombing expanded into the whole lung. One case revealed diffuse ground glass opacity. In 12 of 40 cases in the normal KL-6 group, CT scores mildly increased compared with the other cases (over 20 points). The predominant finding of these cases could be classified into four types: (1) narrow spread honeycombing; (2) subtle fibrosis; (3) airway diseases; and (4) dense consolidation.

CONCLUSION

KL-6 is a useful marker to detect severe RA lung disease. It is also useful to distinguish non-fibrosis from fibrosis predominant cases. However, it sometimes could not detect early stage RA lung disease.

Elevation of KL-6, a lung epithelial cell marker, in plasma and epithelial lining fluid in acute respiratory distress syndrome

KL-6 is a pulmonary epithelial mucin more prominently expressed on the surface membrane of alveolar type II cells when these cells are proliferating, stimulated, and/or injured. We hypothesized that high levels of KL-6 in epithelial lining fluid and plasma would reflect the severity of lung injury in patients with acute lung injury (ALI). Epithelial lining fluid was obtained at onset (day 0) and day 1 of acute respiratory distress syndrome (ARDS)/ALI by bronchoscopic microsampling procedure in 35 patients. On day 0, KL-6 and albumin concentrations in epithelial lining fluid were significantly higher than in normal controls (P < 0.001), and the concentrations of KL-6 in epithelial lining fluid (P < 0.002) and in plasma (P < 0.0001) were higher in nonsurvivors than in survivors of ALI/ARDS. These observations were corroborated by the immunohistochemical localization of KL-6 protein expression in the lungs of nonsurvivors with ALI and KL-6 secretion from cultured human alveolar type II cells stimulated by proinflammatory cytokines. Because injury to distal lung epithelial cells, including alveolar type II cells, is important in the pathogenesis of ALI, the elevation of KL-6 concentrations in plasma and epithelial lining fluid could be valuable indicators for poor prognosis in clinical ALI.

Changes in serum KL-6 after intravenous fosfomycin administration in idiopathic interstitial pneumonia

Changes in serum KL-6 levels after intravenous fosfomycin (FOM) administration in idiopathic interstitial pneumonia (IIP) were studied. Seventeen patients who were diagnosed with usual interstitial pneumonia by surgical lung biopsy were selected as subjects. In these patients, FOM was administered intravenously, at a dose of 2 g twice daily, for 14 days, and serum KL-6 was determined before and after its administration. FOM administration resulted in a reduction of serum KL-6 in all 17 patients (1273 +/- 132 U/ml [mean +/- SEM] to 1023 +/- 101 U/ml; P < 0.01). FOM may reduce serum KL-6 in IIP and may be an appropriate therapeutic drug for this condition.

Study of Clara Cell 16, KL-6, and Surfactant Protein-D in Serum as Disease Markers in Pulmonary Sarcoidosis

STUDY OBJECTIVES

To determine the discriminative value of serum Clara cell 16 (CC16), KL-6, and surfactant protein (SP)-D as markers of interstitial lung diseases, and their ability to reflect pulmonary disease severity and prognosis in sarcoidosis.

SUBJECTS

Seventy-nine patients with sarcoidosis and 38 control subjects.

MEASUREMENTS

Serum CC16, KL-6, and SP-D concentrations at disease presentation were measured. Pulmonary function tests and chest radiographs were analyzed at presentation and 2-year follow-up.

RESULTS

All markers co-correlated, and a significant difference was found between CC16, KL-6 (Krebs von den Lungen-6), and SP-D levels in patients with sarcoidosis and control subjects (p < 0.0001). Receiver operating characteristic curve analysis revealed largest area under the curve for KL-6. Significantly higher levels of CC16 and KL-6 were found in patients with parenchymal infiltration (stage II, III) compared to patients without parenchymal infiltration (stage I). In concordance, CC16 and KL-6 levels inversely correlated with diffusion capacity and total lung capacity, and KL-6 also with inspiratory vital capacity. Moreover, higher KL-6 levels were weakly but significantly associated with persistence or progression of parenchymal infiltrates at 2-year follow-up.

CONCLUSION

In this study, KL-6 appears to be the best discriminative marker in differentiating patients with sarcoidosis from healthy control subjects; however, as it is not a specific marker for this condition, this quality is unlikely to be useful as a diagnostic tool. Both CC16 and KL-6 may be of value in reflecting disease severity, and KL-6 tends to associate with pulmonary disease outcome.

KL-6, a human MUC1 mucin, is expressed early in premature lung

KL-6, one of the MUC1 antigens, is a mucin-like high-molecular-weight glycoprotein, which is strongly expressed on type II pneumocytes. Serum levels of KL-6 have been shown to correlate with activity of interstitial pneumonia (IP). During embryonic development, MUC1 expression coincides with the onset of epithelial sheet and glandular formation. To investigate the potential role of KL-6 in lung morphogenesis, we examined KL-6 expression by immunohistochemistry on autopsied lung tissue specimens of 35 neonates and infants with gestational age from 23 to 40 weeks. Hyaline membranes (HMs) were detected in 13 of 35 cases. Simultaneously, antibody against surfactant protein A (SP-A) was employed in the study which is a distinct marker for type II pneumocytes. In all cases studied with gestational age above 23 weeks, staining for KL-6 was strongly positive in alveolar epithelial cells and in HMs found in 13 cases, whereas immunoreaction for PE10 varied depending on gestational age and duration of postnatal survival. Our findings suggest that KL-6 is expressed earlier in premature lung and may act as an important factor contributing to morphogenesis and function of developing lung in early gestation.

Serum KL-6 levels in pediatric patients: reference values for children and levels in pneumonia, asthma, and measles patients

Serum KL-6 reflects alveolar damage and regeneration of type II pneumocytes, indicating disease activity in various interstitial lung diseases. We conducted a descriptive and observational multiple case-control study to determine the distribution of serum KL-6 levels in pediatric patients with or without respiratory diseases. Subjects were recruited from the patients of a teaching hospital in the suburb of Tokyo. A consecutive series of 401 children (0-16 years old) underwent blood sampling for many clinical reasons. They comprised the following four groups: pneumonia (n = 96), bronchial asthma (n = 101), measles (n = 102), and nonrespiratory diseases (n = 102) as a control group. Standard upper limits of serum KL-6 in a group of children with nonrespiratory disease were 250 U/mL, or half the adult level. No gender or age differences were observed. Elevated serum KL-6 concentrations were observed in severe pneumonia, acute exacerbations of asthma, and measles pneumonia. In the measles group, KL-6 values reflected the presence and severity of complicating pneumonia. We conclude that serum KL-6 levels exceeding 250 U/mL were rarely observed in children without respiratory diseases. In contrast, a substantial proportion of children with common respiratory diseases showed mild to moderate increases in serum KL-6 levels. Elevated serum KL-6 in these children may reflect the presence of alveolar damage, followed by regeneration of type II pneumocytes. However, in order to use serum KL-6 as a marker of interstitial lung diseases in children, a cutoff level should be determined separately.

Comparative study of KL-6, surfactant protein-A, surfactant protein-D, and monocyte chemoattractant protein-1 as serum markers for interstitial lung diseases

KL-6, surfactant protein (SP)-A, SP-D, and monocyte chemoattractant protein-1 (MCP-1) are reported to be sensitive markers for interstitial lung diseases (ILD). However, each marker has been studied independently. The aim of this study was a comparative analysis of the diagnostic values of these markers. Subjects consisted of 33 patients with ILD (21 cases of idiopathic pulmonary fibrosis and 12 associated with collagen vascular diseases) and 82 control subjects (12 cases of bacterial pneumonia and 70 healthy volunteers). Receiver operating characteristic curves revealed that KL-6 was superior to the other markers. The cut-off levels for these markers that resulted in the highest diagnostic accuracy were determined to be 465 U/ml for KL-6, 48.2 ng/ml for SP-A, 116 ng/ml for SP-D, and 1080 pg/ml for MCP-1. The sensitivity, specificity, and diagnostic accuracy were 93.9%, 96.3%, and 95.7% for KL-6; 81.8%, 86.6%, and 85.2% for SP-A; 69.7%, 95.1%, and 87.8% for SP-D; and 51.5%, 92.7%, and 80.9% for MCP-1; respectively. The serum levels of SP-A and SP-D, but not of KL-6, were significantly higher in patients with bacterial pneumonia than in healthy volunteers. These results suggest that of the markers studied, KL-6 is the best serum marker for ILD.

Natural autoantibody to MUC1 is a prognostic indicator for non-small cell lung cancer

A great deal of attention has been focused on the antitumor effects of anti-MUC1 humoral and cellular responses. We examined whether anti-MUC1 antibody is present in patients with lung cancer, and evaluated its prognostic value. Serum was obtained from 30 patients with nonresectable, non-small cell lung cancer (NSCLC) and 60 healthy volunteers. The presence of anti-MUC1 antibody was determined by enzyme-linked immunosorbent assay. The patients were observed for a median follow-up time of 54.0 mo. Overall survival was estimated by the Kaplan-Meier method. Multivariate analyses were performed using the Cox proportional hazards regression model. Anti-KL-6/MUC1 antibody levels of the patients were significantly lower than those of normal individuals (p < 0.001). One-year survival rate of patients with high concentrations of anti-KL-6/MUC1 antibody was significantly higher than that of patients with low levels of anti-KL-6/MUC1 antibody (90.9% versus 21.1%, p < 0.001). Anti-KL-6/MUC1 antibody status was most strongly correlated with mortality, followed by lymph node status and albumin levels, whereas sex, serum lactate dehydrogenase (LDH), and carcinoembryonic antigen (CEA) levels, and metastasis status did not correlate with mortality. These preliminary results indicate that the degree of decrease in antibody level may be associated with a patient's prognosis.

Circulating KL-6 predicts the outcome of rapidly progressive idiopathic pulmonary fibrosis

Searching for early predictive markers of the therapeutic effects of high-dose corticosteroids ("pulse therapy") on patients with rapidly progressing idiopathic pulmonary fibrosis (IPF), we evaluated 14 such patients, who had received weekly pulse therapy for at least 3 wk. Eight patients responded to the treatment and survived. However, six patients failed to respond, and all of them died within 3 mo after treatment. Serum levels of KL-6 (MUC1 mucin), neutrophil elastase (NE), and lactate dehydrogenase (LDH) were measured before, and at 1 wk and 3 wk after treatment. Levels of KL-6 decreased significantly in patients who lived, whereas KL-6 levels tended to increase in patients who died. The values of NE did not change significantly. LDH levels decreased significantly at 1 wk, and tended to decrease at 3 wk in patients who lived. However, in patients who died, they did not significantly change. At the first cycle of treatment when clinical effects may not be evident, the decrease in KL-6 but not LDH levels was significantly related to a favorable outcome, whereas their increase was related to a poor outcome. Results suggest that monitoring with KL-6 may contribute to early clinical decisions for alternative therapy in the management of rapidly progressing IPF.

Comparative evaluation of sialylated carbohydrate antigens, KL-6, CA19-9 and SLX as serum markers for interstitial pneumonia

We compared diagnostic values of three serum carbohydrate antigens, KL-6, CA19-9 and SLX to discriminate interstitial pneumonia (IP) from alveolar pneumonia and healthy volunteers. Subjects consisted of 13 patients with idiopathic pulmonary fibrosis and 10 associated with collagen vascular diseases, 12 patients with sarcoidosis and 70 controls (52 healthy volunteers and 18 patients with alveolar pneumonia). Cut-off values were determined at the level at which the diagnostic accuracy became the highest for each marker, 449 U/mL for KL-6, 26 U/mL for CA19-9 and 41 U/mL for SLX. The sensitivity, the specificity and the diagnostic accuracy were 74.3% (26/35), 98.6% (69/70) and 90.5% (95/105) in KL-6, 42.9% (15/35), 94.3% (66/70) and 77.1% (81/105) in CA19-9, and 20.0% (7/35) and 95.7% (67/70) and 70.5% (74/105) in SLX, respectively. Receiver operating characteristic curves revealed that KL-6 was far superior to both CA19-9 and SLX. These results suggest that KL-6 is the best marker for interstitial pneumonia among these carbohydrate antigens.