Serum KL-6 levels in patients with pulmonary complications after allogeneic bone marrow transplantation

Association of serum KL-6 levels with interstitial lung disease in patients with connective tissue disease: a cross-sectional study

It was aimed to evaluate KL-6 glycoprotein levels to determine if it may be a diagnostic marker for the connective tissue diseases (CTDs) predicting CTD-related interstitial lung diseases (ILDs) (CTD-ILD) development and to examine if there was a difference between patients and healthy controls. The study included 113 patients with CTD (45 CTD without lung involvement, 68 CTD-ILD) and 45 healthy control subjects. KL-6 glycoprotein levels were analyzed with ELISA in patients and the control group. The relationship between KL-6 glycoprotein levels and CTD-ILD was assessed. In the comparison of all the groups in the study, significantly higher levels of KL-6 were determined in the CTD-ILD group than in either the CTD without pulmonary involvement group or the healthy control group (p < 0.008 and p < 0.001, respectively). There was no statistically significant difference between the KL-6 levels in the healthy control group and the CTD without pulmonary involvement group (p = 0.289). The KL-6 levels did not differ significantly according to the connective tissue diseases in the diagnostic groups (systemic lupus erythematosus, Sjögren's syndrome, rheumatoid arthritis, mixed connective tissue disease, scleroderma, polymyositis/ dermatomyositis). In the healthy control group, there was a statistically significant difference between KL-6 levels in smokers and non-smokers. Smokers had significantly higher serum KL-6 levels compared with non-smokers (p < 0.05). There was no statistically significant difference between smoking status (pack-year) and serum KL-6 levels. There was no statistically significant correlation between serum KL-6 levels and time since diagnosis of CTD and CTD-ILD. The level of KL-6 as a predictive factor could be used to identify the clinical development of ILD before it is detected on imaging modality. Further prospective clinical studies are needed to define whether levels of KL-6 might have prognostic value or might predict progressive ILD.

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 role of serum KL-6 measurement in common pediatric respiratory infections

KL-6 is a useful marker for interstitial pneumonia of various origins. However, the role of KL-6 in common pediatric respiratory infections is largely unknown. In order to determine whether the KL-6 level is elevated during respiratory infection, and whether KL-6 is a useful biomarker for the disease activity, we evaluated serum KL-6 levels in 132 children with various respiratory infections. KL-6 levels were significantly higher in patients with measles, influenza, or respiratory syncytial virus infection than in the control subjects. On the other hand, KL-6 levels in patients with bacterial infections such as mycoplasma, chlamydia, or pertussis were comparable to the control values. In patients with viral infections, high KL-6 levels, as defined by the mean plus 2 standard deviations of the control group, significantly correlated with low SpO(2) or days of O(2) administration, but did not correlate with C-reactive protein or white blood cell counts. These results indicate that measurement of serum KL-6 levels is helpful for the management of common pediatric respiratory infections.

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.

Idiopathic interstitial pneumonia following stem cell transplantation

Idiopathic interstitial pneumonia (IIP) can occur after stem cell transplantation, but the aetiology is unknown. Based on the association between angiitis syndrome and Helicobacter pylori infection, we identified possible risk factors common to these two conditions. Among 83 patients who underwent stem cell transplantation, four developed IIP. We elucidated various parameters and clinical features in four patients with IIP and 79 patients without, after allogeneic stem cell transplantation. In all four patients, (1) the conditioning regimen induced total body irradiation, (2) serological reactivation of cytomegalovirus and/or human herpesvirus-6 preceded the onset of IIP, (3) their human leucocyte antigen types were among those suspected to increase susceptibility to angiitis syndrome, (4) serum anti-H. pylori antibody was positive before conditioning and remained positive throughout the post-transplantation course, (5) inflammatory cytokines (interleukin-6, 8 and 12) were increased during the period of leucocyte recovery after transplantation and (6) the levels of intercellular adhesion molecule-1, thrombomodulin and plasminogen activator inhibitor-1 were increased at the onset of IIP. These findings suggest the possibility that angiitis syndrome and H. pylori infection are involved in the pathogenesis of post-transplantation IIP.