Elevated serum YKL-40 correlates with clinical characteristics in patients with polymyositis or dermatomyositis

Activity Prediction Modeling Based on a Combination of Growth Differentiation Factor 15 and Serum Biomarker Levels in Dermatomyositis and Polymyositis

AIMS

Growth differentiation factor 15 (GDF15) plays an important role in multiple inflammatory disorders. We aimed to analyze serum GDF15 levels in adult patients with idiopathic inflammatory myopathies (IIMs).

METHODS

Serum GDF15 levels were measured in 179 adult patients with IIMs and 76 healthy controls (HCs). The association between GDF15 levels and disease variables was analyzed using Spearman's rank correlation. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminatory ability of GDF15 and the GDF15-to-lymphocyte ratio (GLR). Machine learning methods were applied to build predictive models.

RESULTS

GDF15 levels and GLR were significantly elevated in patients with adult IIMs than in HCs. Compared with patients in remission, both GDF15 and GLR were significantly higher in myositis patients in an active phase. GDF15 levels correlated positively with myositis disease activity indices and negatively correlated with lymphocyte and platelet counts. ROC curve analysis revealed that GDF15 levels and GLR outperformed muscle enzymes and distinguished well between patients with active disease and those in remission. Furthermore, even in the normal muscle enzyme group, GDF15 levels and GLR were also well-distinguished between patients with active disease and those in remission. Using machine learning, a logistic regression model of GDF15 combined with creatine kinase and lymphocyte count was constructed and had a reliable predictive value for disease activity.

CONCLUSIONS

GDF15, particularly GLR, was significantly correlated with disease activity in adult patients with IIMs. They could serve as useful biochemical markers for evaluating disease activity, monitoring disease progression, and guiding treatment in adult patients with IIMs.

YKL-40 in serum: a promising biomarker of juvenile SLE and strongly correlated with disease duration

BACKGROUND

The biological function of YKL-40 is not well determined in different inflammatory and autoimmune diseases; however, some data highlighted its possible connection with disease activity.

AIM

We investigated the diagnostic utility of serum YKL-40 in patients with SLE and examined its correlation with disease activity. Additionally, we examined any differences in serum YKL-40 levels between juvenile and adult SLE patients.

METHODS

We included 78 female patients with SLE and 42 controls. The level of YKL-40 in serum was measured by ELISA.

RESULTS

The serum YKL-40 level in SLE patients was significantly higher compared to the control group (9 (3) ng/mL vs. 5.5 (0.1) ng/mL; p < 0.001). YKL-40 showed excellent diagnostic utility with an AUC of 1 (p < 0.001) and a cutoff point of 5.6, providing sensitivity and specificity of 100%. YKL-40 was higher in adolescents and those with a positive family history of SLE (p = 0.01 for both) and positively correlated with disease duration (r = 0.45, p < 0.001). YKL-40 level was significantly higher in patients with photosensitivity, fever, vasculitis, blood disorders, positive anti-dsDNA, and APL ab (p < 0.05 for all). Conversely, patients with skin manifestations had a significantly lower YKL-40 (p = 0.004). In juvenile SLE, the AUC was 0.65 and a p-value of 0.01, and at a cutoff value of (8.7) ng/mL, the sensitivity and specificity were 72% and 60%, respectively.

CONCLUSION

YKL-40 in serum could be a promising biomarker in patients with SLE, especially in adolescent-onset cases. It is independently influenced by disease duration, anemia, thrombocytopenia, positive anti-dsDNA, and APL ab features.

Involvement of YKL-40-positive macrophages commonly identified in polymyositis and dermatomyositis in the pathogenesis of myositis: a retrospective study

YKL-40 is implicated in inflammation and tissue repair, but no reports have investigated its involvement in myositis in polymyositis (PM) and dermatomyositis (DM). Therefore, we aimed to investigate the relationship between YKL-40 and PM/DM. We retrospectively enrolled 35 patients diagnosed with PM/DM along with 26 healthy controls (HCs). Both PM and DM were diagnosed according to Bohan and Peter's criteria. Serum YKL-40 levels were measured, age-corrected to YKL-40 percentile values, and compared to HCs. Patients with myositis without interstitial lung disease were also enrolled and compared to HCs. Immunofluorescence staining was performed to identify YKL-40-positive inflammatory cells in muscle biopsy samples from two patients each with PM and DM. Age-corrected serum YKL-40 levels were significantly higher in patients with PM/DM compared to HCs with and without lung disease; however, these levels decreased significantly after treatment. Immunohistochemical analysis showed infiltration of YKL-40-positive inflammatory cells into the intramuscular sheath and perimuscular membrane. Immunofluorescence staining showed CD68 expression in YKL-40-positive inflammatory cells, suggesting that these cells were macrophages. To the best of our knowledge, this is the first study to demonstrate that YKL-40-positive macrophages are present in PM and DM, indicating that YKL-40 may be involved in PM/DM.

Autoimmune inflammatory myopathy biomarkers

The autoimmune inflammatory myopathy disease spectrum, commonly known as myositis, is a group of systemic diseases that mainly affect the muscles, skin and lungs. Biomarker assessment helps in understanding disease mechanisms, allowing for the implementation of precise strategies in the classification, diagnosis, and management of these diseases. This review examines the pathogenic mechanisms and highlights current data on blood and tissue biomarkers of autoimmune inflammatory myopathies.

YKL-40 serum levels are predicted by inflammatory state, age and diagnosis of idiopathic inflammatory myopathies

YKL-40 increase according to the aging process, and its functions have been associated with tissue remodeling and systemic inflammation. In Rheumatoid Arthritis (RA) it has been proposed as a possible biomarker of activity and severity, however; in the field of idiopathic inflammatory myopathies (IIM) the role of YKL-40 in IIM is not clear. Thus, we aimed to evaluate if there is an association between the serum levels and muscle tissue expression of YKL-40 with age, IIM phenotype, muscle strength and myositis disease activity. The main finding was that age is the most important variable that affects the YKL-40 serum levels. In muscle biopsy, we observed that YKL-40 is mainly expressed in infiltrating lymphoid cells than in muscle tissue. Using ANCOVA according to the b-coefficients, YKL-40 serum levels are predicted by inflammatory state, age, and IIM diagnosis.

Polymyositis and dermatomyositis biomarkers

Polymyositis (PM) and dermatomyositis (DM) are the two subtypes of idiopathic inflammatory myositis and are characterized as symmetrical progressive muscle weakness in the proximal extremities. PM/DM affect multiple organs and systems, including the cardiovascular, respiratory and digestive tract systems. An in-depth understanding of PM/DM biomarkers will facilitate development of simple and accurate strategies for diagnosis, treatment, and prognosis prediction. This review summarized the classic biomarkers of PM/DM, including anti-aminoacyl tRNA synthetases (ARS) antibody, anti-Mi-2 antibody, anti-melanoma differentiation-associated gene 5 (MDA5) antibody, anti-transcription intermediary factor 1-γ (TIF1-γ) antibody, anti-nuclear matrix protein 2 (NXP2) antibody, among others. Among them, anti-aminoacyl tRNA synthetases antibody is the most classic. In addition, many potential novel biomarkers were also discussed in this review, including anti-HSC70 antibody, YKL-40, interferons, myxovirus resistance protein 2, regenerating islet-derived protein 3-α, interleukin (IL)-17, IL-35, microRNA (miR)-1 and so on. Among the biomarkers of PM/DM described in this review, classic biomarkers have become the mainstream biomarkers to assist clinicians in diagnosis due to their early discovery, in-depth research, and widespread application. The novel biomarkers also have potential and broad research prospects, which will make immeasurable contributions to exploring biomarker-based classification standards and expanding their application value.

Clinical value of YKL-40 in patients with polymyositis/dermatomyositis: A cross-sectional study and a systematic review

INTRODUCTION

We performed a cross-sectional study to investigate the clinical usefulness of YKL-40 in patients with dermatomyositis (DM) and conducted a systematic review to summarize the clinical value of YKL-40 in patients with polymyositis (PM)/DM.

MATERIALS AND METHODS

A cross-sectional study and a systematic review were performed to study the clinical value of YKL-40 in patients with PM/DM. Serum YKL-40 level was detected using enzyme-linked immunosorbent assay, and its association with clinical and laboratory parameters was analyzed. In the systematic review, electronic databases of OVID Embase, OVID Medline, and web of science were searched to collect studies that reported clinical use of YKL-40 in patients with PM/DM.

RESULTS

In the cross-sectional study, serum YKL-40 level was higher in patients with DM than in healthy controls (median [interquartile range]: 84.09 [52.72-176.4] ng/ml versus 27.37 [12.30-53.58] ng/ml, p < 0.0001). Serum levels of YKL-40 were associated with the course of DM (r = -0.469, p < 0.001), CRP (r = 0.303, p = 0.043), CK (r = 0.263, p = 0.037), and global disease activity (r = 0.628, p < 0.001). The area under the ROC curve was 0.835 (95% confidence interval 0.751-0.920). In the systematic review, a total of four studies were included with moderate to high quality. Serum level of YKL-40 has the possibility for diagnosing PM/DM, identifying PM/DM patients with interstitial lung disease (ILD) or rapid progress ILD, and predicting death.

CONCLUSION

Serum YKL-40 level is a possible useful biomarker for PM/DM diagnosis and may be used to predict prognosis.

High YKL-40 serum levels and its expression in the muscle tissues of patients with antisynthetase syndrome

BACKGROUND

The protein chitinase-3-like-1 (YKL-40) is rarely analyzed in patients with myositis. Therefore, we aimed to evaluate YKL-40 serum levels; correlate them with laboratory and clinical parameters, disease status, and treatment schemes; and analyze the YKL-40 expression in the muscle tissues of patients with antisynthetase syndrome (ASSD).

METHODS

This cross-sectional single-center study included 64 adult patients with ASSD who were age-, gender-, and ethnicity-matched to 64 healthy control individuals. Their YKL-40 serum levels were analyzed using the Enzyme-Linked Immunosorbent Assay (ELISA) kit method, while YKL-40 expression in muscle tissues was analyzed using an immunohistochemical technique. Disease status was assessed using the International Myositis Assessment and Clinical Studies Group (IMACS) set scores.

RESULTS

The patients' mean age was 44.8 ± 11.8 years, and median disease duration was 1.5 (0.0-4.0) years. These patients were predominantly female (82.8%) and Caucasian (73.4%). Most patients had stable disease. The median YKL-40 serum level was significantly higher in patients with ASSD when compared to the healthy individuals: 538.4 (363.4-853.1) pg/mL versus 270.0 (201.8-451.9) pg/mL, respectively; P < 0.001. However, YKL-40 serum levels did not correlate with any clinical, laboratory, disease status, or therapeutic parameters (P > 0.050), except tumor necrosis factor alpha (TNF-α) serum levels (Spearman's correlation, rho = 0.382; P = 0.007). YKL-40 was highly expressed by inflammatory cells found in muscle biopsy specimens.

CONCLUSIONS

High YKL-40 serum levels were observed in patients with ASSD and correlated positively with TNF-α serum levels. Moreover, YKL-40 was expressed by the inflammatory cells of the muscle tissue.

Can YKL-40 be used as a biomarker for interstitial lung disease?: A systematic review and meta-analysis

BACKGROUND

Interstitial lung disease (ILD) has a poor prognosis and lacks specific biomarkers for early diagnosis, assessment of disease severity, and prognosis. YKL-40 levels were found to be elevated in patients with ILD, but these results are inconsistent. Therefore, we conducted a systematic review and meta-analysis to accurately study the relation between YKL-40 and ILD.

METHODS

We performed a systematic literature search in many databases (PubMed, Embase, the China National Knowledge Infrastructure, and Wanfang databases) and commercial Internet search engines to identify studies involving the role of YKL-40 in patients with ILD. The weighted mean difference with its 95% confidence interval were used to investigate the effect sizes. If obvious heterogeneity was found in the meta-analysis, the level of YKL-40 was directly compared by the Mann-Whitney test.

RESULTS

Sixteen eligible articles were finally identified. The results showed that the serum YKL-40 levels of patients with idiopathic pulmonary fibrosis, connective tissue-related ILD, sarcoidosis, cryptogenic tissue pneumonia, asbestosis-ILD, and idiopathic nonspecific interstitial pneumonia were higher than those in controls, but there was no increase in patients with pulmonary alveolar proteinosis. We also found that there are certain differences in the serum YKL-40 levels in patients with different types of ILD. The results showed that the bronchoalveolar lavage fluid YKL-40 levels of patients with idiopathic pulmonary fibrosis were significantly higher than that in controls. A systematic review indicated that there were correlations between the serum YKL-40 levels and lung function in patients with different ILD. In addition, YKL-40 may be used as a valuable biomarker for survival, with risk ratios ranging from 1.006 to 10.9.

CONCLUSIONS

This study suggests that YKL-40 may be a useful biomarker for the diagnosis and prognosis of ILD.

Relationships between increased circulating YKL-40, IL-6 and TNF-α levels and phenotypes and disease activity of primary Sjögren's syndrome

BACKGROUND

There is now no single score or marker useful for evaluating disease activity of primary Sjögren's syndrome (pSS). This study was designed to explore the associations of circulating YKL-40, interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) with systemic activity and phenotypes of pSS.

METHODS

This study included 58 pSS patients and 30 healthy controls (HC). The sera were measured by multiplex immunoassay for YKL-40, IL-6 and TNF-α concentrations. The disease activity of pSS patients was evaluated by European league against rheumatism (EULAR) SS disease activity index (ESSDAI). Local severity was assessed in accordance with the Tarpley score.

RESULTS

Serum YKL-40, IL-6 and TNF-α levels significantly elevated in pSS patients compared with those in HC (all P < 0.001). These cytokines correlated with ESSDAI, ESR, CRP, and IgG (all P < 0.05). Serum YKL-40 level correlated markedly with age (r = 0.405, P = 0.002), neutrophil count (r = 0.399, P = 0.002) and neutrophil-to-lymphocyte ratio (NLR) (r = 0.401, P = 0.002), while IL-6 did weakly with NLR (r = 0.296, P = 0.024) and C3 (r = 0.288, 0.036). Serum levels of all three cytokines were substantially lower in patients with eye/mouth dryness vs. those without (all P < 0.05). Additionally, patients with pulmonary, renal involvement or anemia had remarkably higher concentrations of YKL-40 (all P < 0.05), while those with leukocytopenia had lower levels (P = 0.01). Fever or anemia patients showed higher serum concentrations of IL-6 (both P < 0.05), while serum levels of TNF-α were much higher in patients with presence of ANA, anti-SSA or anti-SSB antibodies (All P < 0.05). Serum IL-6 level correlated strongly with YKL-40 (r = 0.452, P < 0.001) and TNF-α (r = 0.743, P < 0.001) in pSS patients. A significant correlation was also found between YKL-40 and TNF-α (r = 0.308, P = 0.022) .

CONCLUSION

The circulating YKL-40, IL-6 and TNF-α levels increase in pSS, and all of them are significantly correlated with indicators (ESSDAI, ESR, CRP, and IgG) for systemic inflammation of pSS. Each cytokine is separately associated with specific pSS phenotype.

Correlation of PMN elastase and PMN elastase-to-neutrophil ratio with disease activity in patients with myositis

Background

Polymorphonuclear (PMN) elastase plays an important role in a variety of inflammatory disorders. Our aim was to analyse PMN elastase in idiopathic inflammatory myopathies (IIMs) and its association with disease activity.

Methods

PMN elastase levels were measured using enzyme-linked immunosorbent assay in serum samples obtained from 74 patients with myositis (58 with dermatomyositis [DM] and 16 with polymyositis [PM]) and 22 healthy controls. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminant capacity of PMN elastase level and PMN elastase-to-neutrophil ratio (ENR) in patients with active and remission myositis. The association of serum PMN elastase level and ENR with disease variables was evaluated in patients with IIMs. The disease specificity of PMN elastase level and ENR was further examined in 60 patients with other systemic autoimmune diseases.

Results

PMN elastase level and ENR were significantly higher in patients with active IIMs, DM, and PM than in patients with remission. ROC curve analysis revealed that PMN elastase level and ENR both outperformed creatine kinase (CK), the currently used laboratory marker, and strongly discriminated patients with active disease and those with remission of IIMs, DM, and PM (area under the ROC curve [AUC] 0.9, 0.9, and 0.88 for PMN elastase; AUC 0.96, 0.96, and 1.0 for ENR; AUC 0.72, 0.70, and 0.80 for CK, respectively). PMN elastase level and ENR were positively correlated with myositis disease activity assessment, CK, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, C-reactive protein, and erythrocyte sedimentation rate. PMN elastase level and ENR were higher in the anti-PM-Scl positive myositis group than those in the anti-PM-Scl negative myositis group. Nevertheless, PMN elastase was not a specific disease marker for IIMs when compared with other autoimmune diseases.

Conclusions

PMN elastase, particularly ENR, were significantly correlated with disease activity and could serve as useful biochemical markers for evaluating the disease activity of patients with IIMs. Thus, they are potentially helpful in monitoring disease progression and guiding treatment.

The new marker YKL-40, a molecule related to inflammation, is associated with cardiovascular events in stable haemodialysis patients

Background

YKL-40 is a glycoprotein associated with inflammatory conditions, including atherosclerosis and endothelial dysfunction. The objective was to analyse serum YKL-40 levels in a haemodialysis population and explore their association with dialysis dosing measures, inflammation, body composition and development of cardiovascular (CV) events.

Methods

We performed a prospective study of 78 chronic haemodialysis patients enrolled in 2013 and followed up until 2018. At baseline, serum YKL-40, inflammatory and nutrition markers and body composition were assessed. During a median follow-up of 43 (interquartile range 24–66) months, CV events were recorded.

Results

The mean age of patients was 62 ± 16 years and 66% were men. The mean YKL-40 was 207 ± 106 ng/dL. Higher YKL-40 levels were associated with lower Kt/V_urea, convective volume, serum albumin and prealbumin and with higher troponin T. During follow-up, 50% developed CV events. Cox analysis showed an association between CV events and YKL-40, diabetes, hypertension, C-reactive protein, lower prealbumin, β₂-microglobulin, glycosylated haemoglobin and troponin T values. The multivariate Cox analysis confirmed an independent association between CV events and YKL-40 {hazard ratio [HR] 1.067 [95% confidence interval (CI) 1.009–1.211]; P: 0.042}, troponin T [HR 1.037 (95% CI 1.009–1.683); P: 0.007], lower prealbumin [HR 0.827 (95% CI 0.224–0.988); P: 0.009] and diabetes [HR 2.103 (95% CI 1.554–3.172); P: 0.008]. Kaplan–Meier confirmed the association between CV events and YKL-40 (log rank 7.28; P = 0.007).

Conclusions

YKL-40 is associated with CV events in haemodialysis patients. Higher dialysis dose and convective volume are associated with lower serum YKL-40 levels.