KL-6 is a potential marker for interstitial lung disease associated with juvenile dermatomyositis

Lung involvement in juvenile idiopathic inflammatory myopathy: A systematic review

OBJECTIVE

Juvenile idiopathic inflammatory myopathies (JIIM) are a group of connective tissue disorders characterized by muscle inflammation and variable systemic involvement, including interstitial lung disease (ILD). Available data on JIIM-associated ILD are very limited. We performed a systematic review of the available clinical, laboratory, and radiological features of JIIM-associated ILD.

METHODS

A systematic literature review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

RESULTS

A total of 90 patients were identified, of whom 77.8% had JDM, 10% amyopathic JDM, 7.8% anti-synthetase syndrome, 3.3% overlap syndrome, and 1.1% juvenile polymyositis. Anti-melanoma differentiation-associated gene 5 (MDA-5/CADM-140) was the most frequently reported myositis-specific antibody (32.2%). At diagnosis of ILD, 55.5% of patients had respiratory symptoms. Ground glass opacity was the most reported radiological feature (52.9%). Thirty-three % of patients developed rapidly progressive (RP) lung disease; 26.7% were admitted to the intensive care unit (ICU); 28.9% died; all deaths were due to ILD, with a median interval of 2 months (IQR 1.5-4.7) between the onset of respiratory symptoms and death. Patients admitted to the ICU and who died of ILD were more likely to be male, to have a rapidly progressive pattern, progression of radiological features, and a higher level of KL-6.

CONCLUSIONS

MDA-5/CADM-14 is associated with RP-ILD. ILD is a rare but severe manifestation among the spectrum of systemic involvement associated with JIIM, with a high rate of ICU admission and mortality. Early recognition and aggressive treatment are needed to prevent a severe outcome.

Successful rituximab treatment for severe rapidly progressive interstitial lung disease with anti-MDA5 antibody-positive juvenile dermatomyositis: a case report and literature review

BACKGROUND

Rapidly progressive (RP) interstitial lung disease (ILD) is a life-threatening complication of juvenile dermatomyositis (JDM); however, it is generally refractory to treatment; to the best of our knowledge, no evidence-based treatment has been established for RP-ILD yet. We present the case of a 2-year-old girl with RP-ILD who showed resistance to treatment with methylprednisolone, cyclosporine A, cyclophosphamide, immunoglobulin, and plasma exchange (PE) and was finally treated with extracorporeal membrane oxygenation. We further present a literature review of 18 cases of JDM with RP-ILD.

CASE PRESENTATION

A 2-year-old girl presented with malar rash, mild muscle weakness, and weight loss for a few months before admission. She had a history of dry cough and dyspnea for a few days, followed by rapid respiratory failure. The patient was diagnosed with JDM with RP-ILD through physical examination (malar rashes and Gottron's sign) and based on the finding of myositis on femoral magnetic resonance imaging, elevated levels of serum muscle enzymes, positive anti-melanoma differentiation-association gene 5 (MDA5) antibody (> 7,500 index), elevated level of Krebs von den Lungen-6 glycoprotein (KL-6; 3,420 U/mL), and extensive ground-glass opacities with consolidation in the bilateral lungs on chest high-resolution computed tomography. She received combination therapy, including methylprednisolone pulse therapy, followed by oral prednisolone and intravenous cyclosporine A, cyclophosphamide, and immunoglobulin. On day 11 of hospitalization, she was placed on ventilation support and PE was initiated. However, her respiratory condition continued to deteriorate and veno-venous extracorporeal membrane oxygenation was started on day 24 of hospitalization. Rituximab was administered on day 28. After 2 weeks of rituximab therapy initiation, her respiratory condition showed gradual improvements. Eventually, on day 52 of hospitalization, the patient could be weaned off extracorporeal membrane oxygenation. Finally, she was discharged with minimal ventilation support and no neurological complications 11 months after admission.

CONCLUSIONS

Our literature review suggest that JDM with RP-ILD has a high mortality rate. In JDM, rituximab may be a promising treatment option for RP-ILD. In the future, the efficacy of rituximab in the early phases of ILD should be investigated.

Review: Serum Biomarkers of Lung Fibrosis in Interstitial Pneumonia with Autoimmune Features-What Do We Already Know?

Interstitial pneumonia with autoimmune features (IPAF) belongs to a group of diseases called interstitial lung diseases (ILDs), which are disorders of a varied prognosis and course. Finding sufficiently specific and sensitive biomarkers would enable the progression to be predicted, the natural history to be monitored and patients to be stratified according to their treatment. To assess the significance of pulmonary fibrosis biomarkers studied thus far, we searched the PubMed, Medline and Cochrane Library databases for papers published between January 2015 and June 2021. We focused on circulating biomarkers. A primary review of the databases identified 38 articles of potential interest. Overall, seven articles fulfilled the inclusion criteria. This review aims to assess the diagnostic and prognostic value of molecules such as KL-6, SP-A, SP-D, circulating fibrocytes, CCL2, CXCL13, CXCL9, CXCL10 and CXCL11. All of these biomarkers have previously been studied in idiopathic pulmonary fibrosis (IPF) and connective tissue disease-associated interstitial lung disease (CTD-ILD). IPAF is a disorder of a heterogeneous nature. It explains the lack of coherent observations in terms of correlations with functional parameters. There is still no meta-analysis of pulmonary fibrosis biomarkers in IPAF. This is mainly due to the heterogeneity of the methodology and groups analysed in the research. More research in this area is needed.

Respiratory symptoms as initial manifestations of interstitial lung disease in clinically amyopathic juvenile dermatomyositis: a case report with literature review

Background

Clinically amyopathic juvenile dermatomyositis (CAJDM) is a clinical subgroup of juvenile dermatomyositis (JDM), characterized by JDM rashes with little or no clinically evident muscle weakness. Interstitial lung disease (ILD) is an uncommon but potentially fatal complication of juvenile dermatomyositis (JDM). While adults with dermatomyositis-associated ILD usually present respiratory symptoms before or at the same time as skin muscle manifestations, only a few studies have covered the onset of respiratory symptoms of ILD in JDM patients, especially CAJDM. There is currently no clear effective treatment regime or any prognostic factors for CAJDM-associated ILD.

Case presentation

Here, we report the first case of a CAJDM patient who presented with respiratory symptoms as the initial manifestation. A 10-year-old male patient presented to the hospital with a complaint of progressive cough and chest pain. Violaceous macule and papules appeared a few days later and he was positive for anti-Ro-52 antibodies. Imaging showed diffuse interstitial infiltration in both lungs and lung function tests showed restrictive and obstructive ventilatory dysfunction. Muscular abnormalities were excluded by thigh magnetic resonance imaging (MRI) and electromyography. Skin biopsy showed pathognomonic findings consistent with DM. Lung biopsy indicated chronic inflammation of the mucosa. This patient was finally diagnosed with CAJDM complicated by ILD and prescribed methylprednisolone, immunoglobulin, prednisolone and mycophenolate mofetil (MMF) for treatment. The patient’s cutaneous and respiratory manifestations were largely improved. We retrospectively reviewed this and another six cases with CAJDM-associated ILD reported previously to better understand its clinical characteristics and effective management.

Conclusions

Initial respiratory symptoms with rapid progression in patients presenting Gottron papules should be considered manifestations of CAJDM-associated ILD. We also found a combination of corticosteroids, IVIG and MMF to be an effective method of arresting the progress of CAJDM-associated ILD and improving the prognosis of the patients.

Krebs von den Lungen-6 (KL-6) is a pathophysiological biomarker of early-stage acute hypersensitivity pneumonitis among pigeon fanciers

BACKGROUND

Identifying early stages of hypersensitivity pneumonitis (HP) is hampered by variable presentation, heterogeneous or undetected causal antigens and lack of gold-standard biomarkers. Krebs von den Lungen (KL)-6 is pathophysiological biomarker of alveolar epithelial damage. Pigeon fanciers, susceptible to HP, provide a model to investigate early HP.

OBJECTIVE

To test the hypothesis that plasma concentrations of KL-6 are increased in early-stage acute HP.

METHODS

Clinical history, spirometry and blood samples were obtained from pigeon fanciers, 20 with intermittent acute symptoms indicative of developing HP, 27 with no symptoms and 10 healthy subjects with no avian exposure. Plasma KL-6 (units/mL) and pigeon antigen-specific IgG antibody were quantified by enzyme immunoassay. Blood lymphocytes were quantified by flow cytometry and antigen specificity by in vitro cytokine production.

RESULTS

KL-6 was higher in fanciers than controls, median (IQR) 452 (244, 632) vs 274 (151, 377), P = .01. Although fanciers with symptoms had similar antigen exposure and lung function, they had higher KL-6 than those without, 632 (468, 1314) vs 320 (200, 480), P < .001. KL-6 correlated with IgG antibody titre in those with symptoms, r = .591, P = .006. High KL-6, irrespective of symptom category, was associated with higher antibody (P = .006) and lymphocyte proliferation (P = .041), and lower CD4+ T lymphocyte proportion (P = .032).

CONCLUSION AND CLINICAL RELEVANCE

Raised KL-6 is associated with acute symptoms of early-stage HP, and its correlation with antibody may support therapeutic strategies when HP is suspected. KL-6 may act as a mechanistic biomarker of early pathogenesis by linking lung pathophysiological changes with an endotype of immune hypersensitivity.

Clinical practice guidance for juvenile dermatomyositis (JDM) 2018-Update

Juvenile dermatomyositis is the most common type of juvenile idiopathic inflammatory myopathy mainly affecting the skin and proximal muscles. We have published the Japanese version of 'Clinical practice guidance for juvenile dermatomyositis (JDM) 2018 'consisting of a review of articles in the field and evidence-informed consensus-based experts' opinion on the treatment strategy in collaboration with The Pediatric Rheumatology Association of Japan and The Japan College of Rheumatology under the financial support by 'Research on rare and intractable diseases, Health and Labor Sciences Research Grants'. This article is a digest version of the Japanese guidance.

Systemic and Tissue Inflammation in Juvenile Dermatomyositis: From Pathogenesis to the Quest for Monitoring Tools

Juvenile Dermatomyositis (JDM) is a systemic immune-mediated disease of childhood, characterized by muscle weakness, and a typical skin rash. Other organ systems and tissues such as the lungs, heart, and intestines can be involved, but may be under-evaluated. The inflammatory process in JDM is characterized by an interferon signature and infiltration of immune cells such as T cells and plasmacytoid dendritic cells into the affected tissues. Vasculopathy due to loss and dysfunction of endothelial cells as a result of the inflammation is thought to underlie the symptoms in most organs and tissues. JDM is a heterogeneous disease, and several disease phenotypes, each with a varying combination of affected tissues and organs, are linked to the presence of myositis autoantibodies. These autoantibodies have therefore been extensively studied as biomarkers for the disease phenotype and its associated prognosis. Next to identifying the JDM phenotype, monitoring of disease activity and disease-inflicted damage not only in muscle and skin, but also in other organs and tissues, is an important part of clinical follow-up, as these are key determinants for the long-term outcomes of patients. Various monitoring tools are currently available, among which clinical assessment, histopathological investigation of muscle and skin biopsies, and laboratory testing of blood for specific biomarkers. These investigations also give novel insights into the underlying immunological processes that drive inflammation in JDM and suggest a strong link between the interferon signature and vasculopathy. New tools are being developed in the quest for minimally invasive, but sensitive and specific diagnostic methods that correlate well with clinical symptoms or reflect local, low-grade inflammation. In this review we will discuss the types of (extra)muscular tissue inflammation in JDM and their relation to vasculopathic changes, critically assess the available diagnostic methods including myositis autoantibodies and newly identified biomarkers, and reflect on the immunopathogenic implications of identified markers.

Aberrant activation of the type I interferon system may contribute to the pathogenesis of anti-melanoma differentiation-associated gene 5 dermatomyositis

BACKGROUND

Anti-melanoma differentiation-associated gene 5 (MDA5) dermatomyositis (DM) is a distinctive subtype of DM that carries a significant risk of interstitial lung disease (ILD). The mechanisms remain elusive.

OBJECTIVES

To explore the role of the type I interferon (IFN) system in the pathogenesis of anti-MDA5 DM.

METHODS

Twenty patients with anti-MDA5 DM were studied and compared with patients with anti-aminoacyl-tRNA synthetase (ARS) DM (n = 10) and autoantibody-negative patients with DM (n = 20). The levels of inflammatory cytokines, B-cell-activating factor (BAFF) and Krebs von den Lungen (KL)-6 in blood were tested by enzyme-linked immunosorbent assay and multiplex assays. Expressions of transcripts for IFN-associated sensors and type I IFN-inducible genes in peripheral blood mononuclear cells (PBMCs) were detected by real-time polymerase chain reaction. Expressions of the signal transducer and activator of transcription (STAT)1, interferon-stimulated gene (ISG)15 and MxA proteins in skin lesions were analysed by immunohistochemistry.

RESULTS

Plasma IFN-α levels were significantly increased in patients with anti-MDA5 DM. PBMCs from patients with anti-MDA5 DM showed significant upregulation of the TLR3, TLR7, IFIH1 and DDX58 genes, as well as serial IFN-inducible genes. Skin biopsies from patients with anti-MDA5 DM were characterized by strong expression of the STAT1, ISG15 and MxA proteins. In the patients with anti-MDA5 DM and ILD with high IFN-α production, there was a positive quantitative correlation between IFN-α and BAFF (r_s = 0·63, P = 0·044). In addition, the higher levels of BAFF paralleled the higher concentrations of KL-6 (r_s = 0·86, P = 0·0012).

CONCLUSIONS

Our data confirm the aberrant activation of the type I IFN system in anti-MDA5 DM. Overproduction of IFN-α linked with BAFF may be implicated in the development of ILD.

Increased Serum B Cell Activating Factor and a Proliferation-inducing Ligand Are Associated with Interstitial Lung Disease in Patients with Juvenile Dermatomyositis

OBJECTIVE

Rapidly progressive interstitial lung disease (RP-ILD) is an intractable and fatal complication of juvenile dermatomyositis (JDM). This study evaluated serum levels of B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) in JDM patients with complicating ILD, and their association with ILD phenotypes, clinical variables, and anti-melanoma differentiation-associated gene 5 (MDA5).

METHODS

We measured the levels of BAFF, APRIL, and anti-MDA5 in the sera of 23 JDM patients with ILD [8 in the RP-ILD group and 15 in the chronic ILD (C-ILD) group], 17 JDM patients without ILD (non-ILD group), and 10 age-matched controls, using the ELISA method. ILD was identified by high-resolution computed tomography.

RESULTS

Serum BAFF titers were significantly higher in the JDM patients with RP-ILD versus those with C-ILD (p = 0.011) and in healthy controls (p = 0.0004). The C-ILD group had significantly higher levels of BAFF versus controls (p ≤ 0.0001). Serum APRIL was markedly elevated in the RP-ILD group as compared with the C-ILD group (p = 0.003) and controls (p = 0.006). In patients with ILD, both BAFF and APRIL levels were correlated with serum Krebs von den Lungen-6 and interleukin 18. Subjects with high titer anti-MDA5 (> 200 U) had higher levels of BAFF and APRIL than those with low titer anti-MDA5 (< 100 U; p = 0.019 and p = 0.0029, respectively), which may have been due to a relationship between RP-ILD and high anti-MDA5 titer.

CONCLUSION

Our findings of markedly elevated levels of BAFF and APRIL in patients with RP-ILD JDM suggest the potential importance of these cytokines in the diagnosis and treatment of RP-ILD accompanying JDM.

Clinical and laboratory features of fatal rapidly progressive interstitial lung disease associated with juvenile dermatomyositis

OBJECTIVE

Rapidly progressive interstitial lung disease (RP-ILD) is a rare but potentially fatal complication of JDM. The aim of this study was to establish markers for the prediction and early diagnosis of RP-ILD associated with JDM.

METHODS

The clinical records of 54 patients with JDM were retrospectively reviewed: 10 had RP-ILD (7 died, 3 survived), 19 had chronic ILD and 24 were without ILD. Routine tests included a high-resolution CT (HRCT) scan of the chest and measurement of serum levels of creatine phosphokinase, ferritin and Krebs von den Lungen-6 (KL-6). Anti-melanoma differentiation-associated gene 5 (MDA5) antibodies and IL-18 levels were measured by ELISA.

RESULTS

No differences were found in the ratio of juvenile clinically amyopathic DM between the three groups. Initial chest HRCT scan findings were variable and could not distinguish between RP-ILD and chronic ILD. Anti-MDA5 antibodies were positive in all 8 patients with RP-ILD and 10 of 14 with chronic ILD, but none of the patients without ILD. Serum levels of anti-MDA5 antibody, ferritin, KL-6 and IL-18 were significantly higher in the RP-ILD group than in the chronic ILD and non-ILD groups. Serum levels of IL-18 positively correlated with serum KL-6 (R = 0.66, P < 0.001).

CONCLUSION

High serum levels of IL-18, KL-6, ferritin and anti-MDA5 antibodies (e.g. >200 units by ELISA) are associated with RP-ILD. These can be used as an indication for early intensive treatment. Both alveolar macrophages and autoimmunity to MDA5 are possibly involved in the development of RP-ILD associated with JDM.

Predicting the severity of acute bronchiolitis in infants: should we use a clinical score or a biomarker?

Krebs von den Lungen 6 antigen (KL-6) has been shown to be a useful biomarker of the severity of Respiratory syncytial virus bronchiolitis. To assess the correlation between the clinical severity of acute bronchiolitis, serum KL-6, and the causative viruses, 222 infants with acute bronchiolitis presenting at the Pediatric Emergency Department of Estaing University Hospital, Clermont-Ferrand, France, were prospectively enrolled from October 2011 to May 2012. Disease severity was assessed with a score calculated from oxygen saturation, respiratory rate, and respiratory effort. A nasopharyngeal aspirate was collected to screen for a panel of 20 respiratory viruses. Serum was assessed and compared with a control group of 38 bronchiolitis-free infants. No significant difference in KL-6 levels was found between the children with bronchiolitis (mean 231 IU/mL ± 106) and those without (230 IU/mL ± 102), or between children who were hospitalized or not, or between the types of virus. No correlation was found between serum KL-6 levels and the disease severity score. The absence of Human Rhinovirus was a predictive factor for hospitalization (OR 3.4 [1.4-7.9]; P = 0.006). Older age and a higher oxygen saturation were protective factors (OR 0.65[0.55-0.77]; P < 0.0001 and OR 0.67 [0.54-0.85] P < 0.001, respectively). These results suggest that in infants presenting with bronchiolitis for the first time, clinical outcome depends more on the adaptive capacities of the host than on epithelial dysfunction intensity. Many of the features of bronchiolitis are affected by underlying disease and by treatment.

KL-6: a serological biomarker for interstitial lung disease in patients with polymyositis and dermatomyositis

OBJECTIVES

To investigate whether Caucasian patients with polymyositis (PM) or dermatomyositis (DM) and interstitial lung disease (ILD) have elevated serum levels of KL-6 compared with patients without ILD and whether KL-6 could be used as a marker for ILD activity and treatment efficacy of ILD in PM/DM.

DESIGN AND METHODS

Thirty patients with PM/DM (seven with ILD) and 17 age- and sex-matched healthy controls were included in a retrospective, cross-sectional analysis. Twelve patients were followed for longitudinal evaluation. ILD was defined as restrictive lung function impairment with radiographic signs of ILD. Serum KL-6 levels were measured using a sandwich enzyme immunoassay kit. Groups were compared by Mann-Whitney U-test.

RESULTS

PM/DM patients with ILD had significantly higher median serum KL-6 levels compared with those without ILD: 995 (range 533-2318) versus 322 (range 132-1225) U mL(-1) (P = 0.0002). Median serum levels of healthy controls were 225 (range 136-519) U mL(-1) . Serum levels of KL-6 were inversely correlated with percentages of forced expiratory volume in 1 s (FEV1), vital capacity (VC), total lung capacity (TLC), forced VC, diffusing capacity of carbon monoxide (DLco), maximal voluntary ventilation at 40 breaths min(-1) and residual volume (RV). Changes in KL-6 levels showed a significant inverse correlation with changes in percentage FEV1, TLC, DLco and RV. At a cut-off level of 549 U mL(-1) (mean ± 2.5 SD for controls), the sensitivity and specificity for diagnosis of ILD were 83% and 100%, respectively.

CONCLUSION

The level of serum KL-6 may serve as measure of ILD in patients with PM/DM and is a promising biomarker for use in clinical practice to assess clinical response to treatment.

Anti-melanoma differentiation-associated gene 5 antibody is a diagnostic and predictive marker for interstitial lung diseases associated with juvenile dermatomyositis

The presence of the anti-melanoma differentiation-associated gene 5 antibody was evaluated in 13 patients with juvenile dermatomyositis (JDM). The antibody was positive in 5 of the 6 patients with JDM-associated interstitial lung disease (ILD), but not in the 7 patients without ILD. This antibody is a useful marker for early diagnosis of JDM-associated ILD.

Serum KL-6 level and the development of bronchiolitis obliterans syndrome in lung transplant recipients

KL-6 is a glycoprotein expressed by pulmonary epithelial cells, and its serum level has been used as a marker of disease activity in a variety of respiratory illnesses. Previously, we showed that KL-6 was elevated in lung transplant recipients diagnosed with BOS. In this study, we followed serum KL-6 levels and lung functions prospectively in lung transplant recipients who were within the first five-yr post-transplant and had no evidence of BOS at the time of study entry. Mean peak KL-6 levels were 596.16 ± 309.32 U/mL in the nine recipients who developed BOS compared to 352.41 ± 140.68 in 36 recipients who did not (p = 0.05). Six of the nine patients with BOS had an absolute rise in KL-6 above baseline level >200 U/mL compared to two of the 37 who had the same increase in KL-6 but did not develop BOS. Using the 200 U/mL elevation of KL-6 from baseline as a threshold for a positive test would produce a sensitivity of 67%, specificity of 95%, PPV of 75%, and a NPV of 92%. In addition, mean KL-6 levels of patients during acute rejection were not significantly elevated compared to the prerejection mean KL-6 levels (p = 0.71). We conclude that serum KL-6 is a relatively specific marker of BOS in lung transplant recipients.

Juvenile dermatomyositis: clinical characteristics and the relatively high risk of interstitial lung disease

To clarify the clinical features of juvenile dermatomyositis (JDM) in Japanese cases, we retrospectively evaluated the characteristics of 16 children with JDM that were treated at Saitama Children's Medical Center between 1985 and 2004. The age at disease onset ranged from 3.5 to 14.1 years old (7 boys, mean age 7.9 years; 9 girls, mean age 9.2 years). In 14 patients more than two muscle enzymes were elevated at diagnosis. The antinuclear antibody at diagnosis was positive in all girls but one, while it was positive in only two boys (2/7; P<0.01). Three patients were complicated with interstitial lung disease (ILD) (18.8%) and their serum KL-6 levels were already elevated on admission. Our findings suggest that serum KL-6 levels seemed to be sensitive to the detection of ILD in an early phase, and the relatively high frequency of JDM-associated ILD indicated that a careful evaluation of the lungs was therefore required in any individuals with JDM. Of 16 patients, two boys showed a favorable improvement and prognosis without relapse for over 9 years after the termination of treatment. Overall, in girls, there is a tendency to be a delay in the diagnosis/treatment for JDM, and this disease also demonstrated a severe course.

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.

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.

Outcome assessment in the adult and juvenile idiopathic inflammatory myopathies

Through the recent efforts of multi-center collaborative study groups, a number of measures have been developed and partially validated to assess disease activity, disease damage, and health-related quality of life in adult and juvenile patients with IIM. Preliminary core set domains and core set measures of activity and damage have also been developed for adult and juvenile patients with myositis. Validated definitions of improvement and disability should be forthcoming in the next few years. These extraordinary developments will enable much-needed standardization in the assessment of the IIM, particularly in therapeutic and other clinical research studies. Despite this substantial progress, there is a need to develop more sensitive measures to assess IIM disease activity and damage, to further validate the existing tools, to define their performance characteristics in various IIM subgroups, to develop improved imaging techniques that are also quantitative, and to validate activation markers as surrogate measures. The ongoing cooperation of multiple specialists with expertise in these disorders, combined with emerging novel technologies, should continue to enhance the assessment of myositis. Improved clinical care and more rapid development of new therapies for patients with myositis will be the ultimate gains realized from these efforts.

Dermatomyositis: an overview of recent progress with emphasis on dermatologic aspects

Important points regarding DM and C-ADM are as follows: C-ADM is a working functional designation for patients having the skin-only and skin-predominant subsets of DM, amyopathic DM, and hypomyopathic DM. C-ADM seems to have approximately 10% the incidence of classic DM in whites and possibly a higher incidence in Asians. Some patients who present with C-ADM, with or without subclinical laboratory abnormalities, can slowly progress to develop symptomatic muscle weakness over a period of years, whereas others go for 10 to 20 years and longer without the appearance of muscle weakness. C-ADM patients are at risk for potentially life-threatening complications of classic DM, such as interstitial lung disease, which may occur in up to 10% of C-ADM patients. This risk seems to be even greater in some ethnic subgroups (e.g., Japanese). C-ADM patients may also be at increased risk for internal malignancy and until further studies are carried out to confirm the statistical significance of this association, all such patients should have a thorough evaluation for internal malignancy, identical to the approach currently used in classic DM patients. Dermatologists are in the best position initially to diagnose C-ADM patients and can contribute greatly to their overall management and quality of life. Ongoing vigilance is required, however, for complications that can arise in C-ADM patients including potentially fatal interstitial lung disease, internal malignancy, delayed onset of muscle weakness from myositis, and complications of systemic drug therapy. Topical therapy with broad-spectrum sunscreens, anti-inflammatories, and antipruritics should be maximized during the initial management of the cutaneous manifestations of either classic DM or C-ADM. Single-agent or combined aminoquinoline antimalarial therapy represents the safest initial form of systemic therapy for DM-specific skin disease occurring in any clinical setting; however, this approach tends to be less effective in general than for cutaneous LE. There is a theoretical rationale for and limited preliminary successful anecdotal experience with the use of anti-TNF-alpha therapy in refractory cases of classic DM and C-ADM. Cautious systematic clinical trials in this area should be considered.

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.