Translatable plasma and CSF biomarkers for use in mouse models of Huntington's disease

Huntington's disease is an inherited neurodegenerative disorder for which a wide range of disease-modifying therapies are in development and the availability of biomarkers to monitor treatment response is essential for the success of clinical trials. Baseline levels of neurofilament light chain in CSF and plasma have been shown to be effective in predicting clinical disease status, subsequent clinical progression and brain atrophy. The identification of further sensitive prognostic fluid biomarkers is an active research area, and total-Tau and YKL-40 levels have been shown to be increased in CSF from Huntington's disease mutation carriers. The use of readouts with clinical utility in the preclinical assessment of potential therapeutics should aid in the translation of new treatments. Here, we set out to determine how the concentrations of these three proteins change in plasma and CSF with disease progression in representative, well-established mouse models of Huntington's disease. Plasma and CSF were collected throughout disease progression from R6/2 transgenic mice with CAG repeats of 200 or 90 codons (R6/2:Q200 and R6/2:Q90), zQ175 knock-in mice and YAC128 transgenic mice, along with their respective wild-type littermates. Neurofilament light chain and total-Tau concentrations were quantified in CSF and plasma using ultrasensitive single-molecule array (Quanterix) assays, and a novel Quanterix assay was developed for breast regression protein 39 (mouse homologue of YKL-40) and used to quantify breast regression protein 39 levels in plasma. CSF levels of neurofilament light chain and plasma levels of neurofilament light chain and breast regression protein 39 increased in wild-type biofluids with age, whereas total-Tau remained constant. Neurofilament light chain and breast regression protein 39 were elevated in the plasma and CSF from Huntington's disease mouse models, as compared with wild-type littermates, at presymptomatic stages, whereas total-Tau was only increased at the latest disease stages analysed. Levels of biomarkers that had been measured in the same CSF or plasma samples taken at the latest stages of disease were correlated. The demonstration that breast regression protein 39 constitutes a robust plasma biomarker in Huntington's disease mouse models supports the further investigation of YKL-40 as a CSF biomarker for Huntington's disease mutation carriers. Neurofilament light chain and Tau are considered markers of neuronal damage, and breast regression protein 39 is a marker of inflammation; the similarities and differences in the levels of these proteins between mouse models may provide future insights into their underlying pathology. These data will facilitate the use of fluid biomarkers in the preclinical assessment of therapeutic agents for Huntington's disease, providing readouts with direct relevance to clinical trials.

Urinary Biomarkers of Kidney Tubule Health and Mortality in Persons with CKD and Diabetes Mellitus

Key Points

Among adults with diabetes and CKD, biomarkers of kidney tubule health were associated with a greater risk of death, independent of eGFR, albuminuria, and additional risk factors. Higher urine levels of YKL-40 and KIM-1 were associated with a greater risk of death. For cause-specific death, UMOD was independently and inversely associated with the risk of cardiovascular death.

Background

Kidney disease assessed by serum creatinine and albuminuria are strongly associated with mortality in diabetes. These markers primarily reflect glomerular function and injury. Urine biomarkers of kidney tubule health were recently associated with the risk of kidney failure in persons with CKD and diabetes. Associations of these biomarkers with risk of death are poorly understood.

Methods

In 560 persons with diabetes and eGFR ≤60 ml/min per 1.73 m2 from the Reasons for Geographic and Racial Differences in Stroke study (47% male, 53% Black), we measured urine biomarkers of kidney tubule health at baseline: monocyte chemoattractant protein-1 (MCP-1), alpha-1-microglobulin, kidney injury molecule-1 (KIM-1), EGF, chitinase-3-like protein 1 (YKL-40), and uromodulin (UMOD). Cox proportional hazards regression was used to examine the associations of urine biomarkers with all-cause and cause-specific mortality in nested models adjusted for urine creatinine, demographics, mortality risk factors, eGFR, and urine albumin.

Results

The mean (SD) age was 70 (9.6) years, and baseline eGFR was 40 (3) ml/min per 1.73 m2. There were 310 deaths over a mean follow-up of 6.5 (3.2) years. In fully adjusted models, each two-fold higher urine concentration of KIM-1 and YKL-40 were associated with all-cause mortality (hazard ratio [HR] 1.15, 95% confidence interval [CI], 1.01 to 1.31 and 1.13, 95% CI, 1.07 to 1.20, respectively). When examining cause-specific mortality, higher UMOD was associated with a lower risk of cardiovascular death (adjusted HR per two-fold higher concentration 0.87, 95% CI, 0.77 to 0.99), and higher MCP-1 was associated with higher risk of cancer death (HR per two-fold higher concentration 1.52, 95% CI, 1.05 to 2.18).

Conclusion

Among persons with diabetes and CKD, higher urine KIM-1 and YKL-40 were associated with a higher risk of all-cause mortality independently of established risk factors. Urine UMOD and MCP-1 were associated with cardiovascular and cancer-related death, respectively.

ACE2 in chronic disease and COVID-19: gene regulation and post-translational modification

Angiotensin-converting enzyme 2 (ACE2), a counter regulator of the renin-angiotensin system, provides protection against several chronic diseases. Besides chronic diseases, ACE2 is the host receptor for SARS-CoV or SARS-CoV-2 virus, mediating the first step of virus infection. ACE2 levels are regulated by transcriptional, post-transcriptional, and post-translational regulation or modification. ACE2 transcription is enhanced by transcription factors including Ikaros, HNFs, GATA6, STAT3 or SIRT1, whereas ACE2 transcription is reduced by the transcription factor Brg1-FoxM1 complex or ERRα. ACE2 levels are also regulated by histone modification or miRNA-induced destabilization. The protein kinase AMPK, CK1α, or MAP4K3 phosphorylates ACE2 protein and induces ACE2 protein levels by decreasing its ubiquitination. The ubiquitination of ACE2 is induced by the E3 ubiquitin ligase MDM2 or UBR4 and decreased by the deubiquitinase UCHL1 or USP50. ACE2 protein levels are also increased by the E3 ligase PIAS4-mediated SUMOylation or the methyltransferase PRMT5-mediated ACE2 methylation, whereas ACE2 protein levels are decreased by AP2-mediated lysosomal degradation. ACE2 is downregulated in several human chronic diseases like diabetes, hypertension, or lung injury. In contrast, SARS-CoV-2 upregulates ACE2 levels, enhancing host cell susceptibility to virus infection. Moreover, soluble ACE2 protein and exosomal ACE2 protein facilitate SARS-CoV-2 infection into host cells. In this review, we summarize the gene regulation and post-translational modification of ACE2 in chronic disease and COVID-19. Understanding the regulation and modification of ACE2 may help to develop prevention or treatment strategies for ACE2-mediated diseases.

YKL-40 as a novel biomarker related to white matter damage and cognitive impairment in patients with cerebral small vessel disease

YKL-40 is a novel neuroinflammatory marker associated with white matter damage and cognitive dysfunction. 110 CSVD patients, including 54 with mild cognitive impairment (CSVD-MCI), 56 with no cognitive impairment (CSVD-NCI), and 40 healthy controls (HCs) underwent multimodal magnetic resonance examination, serum YKL-40 level detection and cognitive function assessment to investigate the association between YKL-40 and white matter damage and cognitive impairment in cerebral small vessel disease (CSVD) patients. White matter hyperintensities volume was calculated using the Wisconsin White Matter Hyperintensity Segmentation Toolbox (W2MHS) for white matter macrostructural damage evaluation. For white matter microstructural damage evaluation, fractional anisotropy (FA) and mean diffusivity (MD) indices of the region of interest were analyzed based on diffusion tensor imaging (DTI) images using the Tract-Based Spatial Statistics (TBSS) pipeline. The serum YKL-40 level of CSVD was significantly higher than those of HCs, and the CSVD-MCI was higher than in HCs and CSVD-NCI. Furthermore, serum YKL-40 provided high diagnostic accuracy for CSVD and CSVD-MCI. The macroscopic and microstructure of white matter in CSVD-NCI and CSVD-MCI patients indicated different degrees of damage. Disruption of white matter macroscopic and microstructure was significantly associated with YKL-40 levels and cognition deficits. Moreover, the white matter damage mediated the associations between the increased serum YKL-40 levels and cognitive impairment. Our findings demonstrated that YKL-40 might be a potential biomarker of white matter damage in CSVD, whereas white matter damage was associated with cognitive impairment. Serum YKL-40 measurement provides complementary information regarding the neural mechanism of CSVD and its associated cognitive impairment.

YKL-40 as a possible marker of neutrophilic asthma

Asthma is a heterogeneous chronic disorder of the airways, with inflammation and bronchial hyperresponsiveness as its major underlying phenomena. Asthmatics vary in terms of inflammation pattern, concomitant pathologies, and factors aggravating the course of the disease. As a result, there is a need for sensitive and specific biomarkers that could facilitate diagnosing asthma as well as phenotyping in everyday practice. Chitinases and chitinase-like proteins (CLPs) seem promising in this field. Chitinases are evolutionarily conserved hydrolases that degrade chitin. In contrast, CLPs bind chitin but do not have degrading activity. Mammalian chitinases and CLPs are produced by neutrophils, monocytes, and macrophages in response to parasitic or fungal infections. Recently, several questions have been raised about their role in chronic airway inflammation. Several studies demonstrated that overexpression of CLP YKL-40 was associated with asthma. Moreover, it correlated with exacerbation rate, therapy resistance, poor control of symptoms, and, inversely, with FEV₁. YKL-40 facilitated allergen sensitization and IgE production. Its concentration was elevated in bronchoalveolar lavage fluid after an allergen challenge. It was also found to promote the proliferation of bronchial smooth muscle cells and correlate with subepithelial membrane thickness. Thus, it may be involved in bronchial remodeling. Associations between YKL-40 and particular asthma phenotypes remain unclear. Some studies showed that YKL-40 correlates with blood eosinophilia and FeNO, suggesting a role in T2-high inflammation. Quite the opposite, cluster analyses revealed the highest upregulation in severe neutrophilic asthma and obesity-associated asthma. The main limitation in the practical application of YKL-40 as a biomarker is its low specificity. High serum levels of YKL-40 were also found in COPD and several malignancies, in addition to infectious and autoimmune diseases. To conclude, the level of YKL-40 correlates with asthma and some clinical features in the whole asthmatic population. The highest levels are found in neutrophilic and obesity-related phenotypes. However, due to its low specificity, the practical application of YKL-40 remains uncertain but could be useful in phenotyping, especially when combined with other biomarkers.

Role of Vitamins in Cardiovascular Health: Know Your Facts-Part 2

Cardiovascular disease (CVD) is a major cause of morbidity/mortality world-wide, hence preventive interventions are crucial. Observational data showing beneficial CV effects of vitamin supplements, promoted by self-proclaimed experts, have led to ~50% of Americans using multivitamins; this practice has culminated into a multi-billion-dollar business. However, robust evidence is lacking, and certain vitamins might incur harm. This two-part review focuses on the attributes or concerns about specific vitamin consumption on CVD. The evidence for indiscriminate use of multivitamins indicates no consistent CVD benefit. Specific vitamins and/or combinations are suggested, but further supportive evidence is needed. Data presented in Part 1 indicated that folic acid and certain B-vitamins may decrease stroke, whereas niacin might raise mortality; beta-carotene mediates pro-oxidant effects, which may abate the benefits from other vitamins. In Part 2, data favor the anti-oxidant effects of vitamin C and the anti-atherogenic effects of vitamins C and E, but clinical evidence is inconsistent. Vitamin D may provide CV protection, but data are conflicting. Vitamin K appears neutral. Thus, there are favorable CV effects of individual vitamins (C/D), but randomized/controlled data are lacking. An important caveat regards the potential toxicity of increased doses of fat-soluble vitamins (A/D/E/K). As emphasized in Part 1, vitamins might benefit subjects who are antioxidant-deficient or exposed to high levels of oxidative-stress (e.g., diabetics, smokers, and elderly), stressing the importance of targeting certain subgroups for optimal results. Finally, by promoting CV-healthy balanced-diets, we could acquire essential vitamins and nutrients and use supplements only for specific indications.

Chitinase-3-like Protein 1 Is Associated with Poor Virologic Control and Immune Activation in Children Living with HIV

Perinatally infected children living with HIV (CLWH) face lifelong infection and associated inflammatory injury. Chitinase-like 3 protein-1 (CHI3L1) is expressed by activated neutrophils and may be a clinically informative marker of systemic inflammation in CLWH. We conducted a multi-centre, cross-sectional study of CLWH, enrolled in the Early Pediatric Initiation Canadian Child Cure Cohort Study (EPIC⁴). Plasma levels of CHI3L1, pro-inflammatory cytokines, and markers of microbial translocation were measured by enzyme-linked immunosorbent assays. Longitudinal clinical characteristics (viral load, neutrophil count, CD4+ and CD8+ T-lymphocyte counts, and antiretroviral (ARV) regimen) were abstracted from patient medical records. One-hundred-and-five (105) CLWH (median age 13 years, 62% female) were included in the study. Seventy-seven (81%) had viral suppression on combination antiviral therapy (cART). The median CHI3L1 level was 25 μg/L (IQR 19-39). CHI3L1 was directly correlated with neutrophil count (ρ = 0.22, p = 0.023) and inversely correlated with CD4/CD8 lymphocyte ratio (ρ = -0.35, p = 0.00040). Children with detectable viral load had higher levels of CHI3L1 (40 μg/L (interquartile range, IQR 33-44) versus 24 μg/L (IQR 19-35), p = 0.0047). CHI3L1 levels were also correlated with markers of microbial translocation soluble CD14 (ρ = 0.26, p = 0.010) and lipopolysaccharide-binding protein (ρ = 0.23, p = 0.023). We did not detect differences in CHI3L1 between different cART regimens. High levels of neutrophil activation marker CHI3L1 are associated with poor virologic control, immune dysregulation, and microbial translocation in CLWH on cART.

Lithium exposure and chronic inflammation with activated macrophages and monocytes associated with atherosclerosis in bipolar disorder

BACKGROUND

Atherosclerosis accounts for cardiovascular diseases (CVDs). This study aimed to explore the association between carotid intima-media thickness (CIMT), psycho-pharmacotherapy, and inflammatory markers along with other molecules related to atherosclerosis in bipolar disorder (BD).

METHODS

The euthymic patients with bipolar I disorder (BD-I) aged over 20 years were recruited to measure CIMT through ultrasound and the blood levels of lipid profiles, soluble tumor necrosis factor receptor-1 (sTNF-R1), soluble interleukin-6 receptor (sIL-6R), monocyte chemoattractant protein-1, chitinase 3-like 1, endothelial adhesive proteins, and thrombin-antithrombin complex.

RESULTS

Participants were 103 BD-I patients with mean 44.3 years old. The ratio of lithium exposure in relation to illness chronicity and the current daily dosage of lithium therapy exhibited an inverse relationship with CIMT in the entire sample. After controlling for age and BMI, multivariate regression indicated that a higher lithium level was significantly associated with decreased CIMT in the entire sample, high-risk (those with CVDs or endocrine diseases, N = 48), middle-risk (those without CVDs and endocrine diseases, N = 55), and low-risk (those aged <45 years in the middle-risk subgroup, N = 43) subgroups. Furthermore, higher levels of sTNF-R1 in the entire sample and high-risk subgroup and sIL-6R in the middle- and low-risk subgroups were statistically associated with greater CIMT.

LIMITATION

The age range was too wide to control for the effect of age on CIMT and medication.

CONCLUSIONS

Lithium exposure may be a protective factor for atherosclerosis progression in BD-I. The chronic inflammation in BD-I with activated macrophages and monocytes may link with the atherosclerosis development over time.

Interleukin-6 and YKL-40 predicted recurrent stroke after ischemic stroke or TIA: analysis of 6 inflammation biomarkers in a prospective cohort study

OBJECTIVE

Contribution of individual and combined inflammatory markers in prognosis after stroke was still undefined. We aimed to investigate the association of systemic and local vascular inflammatory markers and recurrent stroke as well as impact on poor functional outcome.

METHODS

In this pre-specified substudy of the Third China National Stroke Registry (CNSR-III), 10,472 consecutive acute ischemic stroke or TIA patients with available centralized-measured levels of Interleukin-6 (IL-6), high sensitive C-reactive protein (hsCRP), IL-1 receptor antagonist (IL-1Ra), lipoprotein-associated phospholipase A₂ mass (Lp-PLA₂) and activity (Lp-PLA₂-A), and YKL-40 from 171 sites were enrolled. The primary outcomes consisted of stroke recurrence and poor functional outcome defined as modified Rankin Scale (mRS) score of 2-6 within 1 year.

RESULTS

There were 1026 (9.8%) and 2395 (23.4%) patients with recurrent stroke and poor functional outcome within 1 year. The highest quartiles of IL-6 (adjusted HR, 1.36; 95% CI 1.13-1.64; P = 0.001), hsCRP (adjusted HR, 1.41; 95% CI 1.17-1.69; P = 0.0003) and YKL-40 (adjusted HR, 1.28; 95% CI 1.06-1.56; P = 0.01) were associated with increased risk of recurrent stroke; and the highest quartiles of IL-6 (adjusted OR 1.93; 95% CI 1.64-2.27; P < 0.0001), IL-1Ra (adjusted OR 1.60; 95% CI 1.37-1.87; P < 0.0001), hsCRP (adjusted OR 1.60; 95% CI 1.37-1.86; P < 0.0001) and YKL-40 (adjusted OR 1.21; 95% CI 1.03-1.42; P = 0.02) were correlated with increased risk of poor functional outcome. In the multivariate stepwise regression analysis including all markers with backward selection, elevated levels of IL-6 or YKL-40 were associated with recurrent stroke (IL6: OR, 1.34; 95% CI 1.19-1.52; P < 0.0001; YKL-40: OR, 1.01; 95% CI 1.01-1.03; P = 0.004) and poor functional outcome (IL6: OR, 1.68; 95% CI 1.46-1.93; P < 0.0001; YKL-40: OR, 1.02; 95% CI 1.01-1.03; P = 0.0001). Adding IL-6 and YKL-40 significantly increased the area under the receiver operating characteristic curves for the prediction models of Essen Stroke Risk Score (0.03, P < 0.0001) and Totaled Health Risks in Vascular Events Score (0.07, P < 0.0001), and yielded continuous net reclassification improvement (19.0%, P < 0.0001; 33.0, P < 0.0001).

CONCLUSIONS

In the patients with ischemic stroke or TIA, IL-6 and YKL-40 were independently associated with recurrent stroke and poor functional outcome, and improved risk classification of clinical risk algorithms.

Chitinase 3 like 1 is a regulator of smooth muscle cell physiology and atherosclerotic lesion stability

AIMS

Atherosclerotic cerebrovascular disease underlies the majority of ischaemic strokes and is a major cause of death and disability. While plaque burden is a predictor of adverse outcomes, plaque vulnerability is increasingly recognized as a driver of lesion rupture and risk for clinical events. Defining the molecular regulators of carotid instability could inform the development of new biomarkers and/or translational targets for at-risk individuals.

METHODS AND RESULTS

Using two independent human endarterectomy biobanks, we found that the understudied glycoprotein, chitinase 3 like 1 (CHI3L1), is up-regulated in patients with carotid disease compared to healthy controls. Further, CHI3L1 levels were found to stratify individuals based on symptomatology and histopathological evidence of an unstable fibrous cap. Gain- and loss-of-function studies in cultured human carotid artery smooth muscle cells (SMCs) showed that CHI3L1 prevents a number of maladaptive changes in that cell type, including phenotype switching towards a synthetic and hyperproliferative state. Using two murine models of carotid remodelling and lesion vulnerability, we found that knockdown of Chil1 resulted in larger neointimal lesions comprised by de-differentiated SMCs that failed to invest within and stabilize the fibrous cap. Exploratory mechanistic studies identified alterations in potential downstream regulatory genes, including large tumour suppressor kinase 2 (LATS2), which mediates macrophage marker and inflammatory cytokine expression on SMCs, and may explain how CHI3L1 modulates cellular plasticity.

CONCLUSION

CHI3L1 is up-regulated in humans with carotid artery disease and appears to be a strong mediator of plaque vulnerability. Mechanistic studies suggest this change may be a context-dependent adaptive response meant to maintain vascular SMCs in a differentiated state and to prevent rupture of the fibrous cap. Part of this effect may be mediated through downstream suppression of LATS2. Future studies should determine how these changes occur at the molecular level, and whether this gene can be targeted as a novel translational therapy for subjects at risk of stroke.

Chitinase 3-like-1 is a therapeutic target that mediates the effects of aging in COVID-19

COVID-19 is caused by SARS-CoV-2 (SC2) and is more prevalent and severe in elderly and patients with comorbid diseases (CM). Because chitinase 3-like-1 (CHI3L1) is induced during aging and CM, the relationships between CHI3L1 and SC2 were investigated. Here, we demonstrate that CHI3L1 is a potent stimulator of the SC2 receptor angiotensin converting enzyme 2 (ACE2) and viral spike protein priming proteases (SPP), that ACE2 and SPP are induced during aging, and that anti-CHI3L1, kasugamycin, and inhibitors of phosphorylation abrogate these ACE2- and SPP-inductive events. Human studies also demonstrate that the levels of circulating CHI3L1 are increased in the elderly and patients with CM, where they correlate with COVID-19 severity. These studies demonstrate that CHI3L1 is a potent stimulator of ACE2 and SPP, that this induction is a major mechanism contributing to the effects of aging during SC2 infection, and that CHI3L1 co-opts the CHI3L1 axis to augment SC2 infection. CHI3L1 plays a critical role in the pathogenesis of and is an attractive therapeutic target in COVID-19.

Exploring the Impact of Cerebrovascular Disease and Major Depression on Non-diseased Human Tissue Transcriptomes

Background

The development of complex diseases is contributed by the combination of multiple factors and complicated interactions between them. Inflammation has recently been associated with many complex diseases and may cause long-term damage to the human body. In this study, we examined whether two types of complex disease, cerebrovascular disease (CVD) or major depression (MD), systematically altered the transcriptomes of non-diseased human tissues and whether inflammation is linked to identifiable molecular signatures, using post-mortem samples from the Genotype-Tissue Expression (GTEx) project.

Results

Following a series of differential expression analyses, dozens to hundreds of differentially expressed genes (DEGs) were identified in multiple tissues between subjects with and without a history of CVD or MD. DEGs from these disease-associated tissues-the visceral adipose, tibial artery, caudate, and spinal cord for CVD; and the hypothalamus, putamen, and spinal cord for MD-were further analyzed for functional enrichment. Many pathways associated with immunological events were enriched in the upregulated DEGs of the CVD-associated tissues, as were the neurological and metabolic pathways in DEGs of the MD-associated tissues. Eight gene-tissue pairs were found to overlap with those prioritized by our transcriptome-wide association studies, indicating a potential genetic effect on gene expression for circulating cytokine phenotypes.

Conclusion

Cerebrovascular disease and major depression cause detectable changes in the gene expression of non-diseased tissues, suggesting that a possible long-term impact of diseases, lifestyles and environmental factors may together contribute to the appearance of "transcriptomic scars" on the human body. Furthermore, inflammation is probably one of the systemic and long-lasting effects of cerebrovascular events.

Chitinase 3-like-1 is a Therapeutic Target That Mediates the Effects of Aging in COVID-19

COVID-19 is caused by the SARS-CoV-2 (SC2) virus and is more prevalent and severe in the elderly and patients with comorbid diseases (CM). Because chitinase 3-like-1 (CHI3L1) is induced during aging and CM, the relationships between CHI3L1 and SC2 were investigated. Here we demonstrate that CHI3L1 is a potent stimulator of the SC2 receptor ACE2 and viral spike protein priming proteases (SPP), that ACE2 and SPP are induced during aging and that anti-CHI3L1, kasugamycin and inhibitors of phosphorylation, abrogate these ACE2- and SPP- inductive events. Human studies also demonstrated that the levels of circulating CHI3L1 are increased in the elderly and patients with CM where they correlate with COVID-19 severity. These studies demonstrate that CHI3L1 is a potent stimulator of ACE2 and SPP; that this induction is a major mechanism contributing to the effects of aging during SC2 infection and that CHI3L1 coopts the CHI3L1 axis to augment SC2 infection. CHI3L1 plays a critical role in the pathogenesis of and is an attractive therapeutic target in COVID-19.

Circulating YKL-40 in Philadelphia-negative myeloproliferative neoplasms

Objectives: Philadelphia-negative chronic myeloproliferative neoplasms (MPNs), essential thrombocythemia (ET), polycythemia vera (PV) and myelofibrosis (MF), are characterized by clonal myeloproliferation and a strong inflammatory atmosphere. YKL-40, expressed in granulocytes, macrophages, megakaryocytes and malignant cells, is an acute phase reactant with an important role in tissue remodeling and atherosclerotic inflammation. The aim of this study was to investigate serum YKL-40 levels in MPNs and to assess its clinical correlations. Methods: ELISA test was used to measure serum YKL-40 levels in 111 MPN patients and in 32 healthy controls. Results: Serum YKL-40 levels were higher in ET, post-ET MF, PV, post-PV MF and primary MF patients, when compared to healthy controls (p < 0.001). Higher serum YKL-40 levels were associated with parameters indicative of the increased inflammatory state (higher C-reactive protein, poor performance status, presence of constitutional symptoms and cardiovascular risk factors). Additionally, higher serum YKL-40 levels in MF patients were associated with blast phase disease, lower hemoglobin and higher Dynamic International Prognostic Scoring System score. In the multivariate Cox regression models, higher serum YKL-40 levels in ET and PV patients were independently associated with an increased risk of thrombosis (HR 4.64, p = 0.031) and impaired survival in MF patients (HR 4.31, p = 0.038). Conclusion: These results indicate that higher circulating YKL-40 levels in MPNs might have a pathophysiological role in disease progression and thrombosis development. Assessing circulating YKL-40 could help in identification of ET and PV patients at a high risk of future cardiovascular events and has a good potential for improving prognostication of MF patients.

Serum YKL-40 Levels Are Associated with the Atherogenic Index of Plasma in Children

YKL-40, also known as chitinase-3-like protein 1, is an inflammatory glycoprotein that is secreted by various cell types under acute, chronic, and subclinical inflammation conditions. Elevated serum YKL-40 levels are reportedly independently related to diabetes mellitus, coronary artery disease, acute myocardial infarction, and cardiovascular mortality in adults. Therefore, we aimed to investigate the relationship between serum YKL-40 levels, lipid abnormalities, and the atherogenic index of plasma (AIP) in children. We enrolled 479 children aged 10–12 years (mean age: 11.52) in this general population-based, cross-sectional study. All subjects completed questionnaires and were subjected to multifrequency bioelectrical impedance analysis (BIA) to measure their height, weight, and body mass index (BMI). We collected serum samples from all participants to measure YKL-40, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels. Mean serum YKL-40 levels were significantly higher in the low-HDL-C (p = 0.017) and high-TG (p = 0.010) groups but were not related to TC and LDL-C levels. YKL-40 levels were also higher in the high AIP group (p = 0.007). After adjusting for age, gender, and BMI z-score, the associations between serum YKL-40 levels and TG levels (p = 0.003), the TG-to-HDL-C ratio (p = 0.019), and the AIP value (p = 0.012) remained significant. Based on these findings, we suggest that serum YKL-40 may be a useful initial screening tool or follow-up risk indicator for lipid abnormalities, atherosclerosis, and cardiovascular disease in children and adolescents with risk factors, regardless of obesity.

Adenovirus vector-mediated YKL-40 shRNA attenuates eosinophil airway inflammation in a murine asthmatic model

Recent studies have revealed that YKL-40 is involved in the pathogenesis of asthma. However, its specific mechanism remains unclear. The present study aims to investigate the effect of adenovirus vector-mediated YKL-40 short hairpin RNA (shRNA) on regulation of airway inflammation in a murine asthmatic model. Mice were assessed for airway hyperresponsiveness (AHR), total leukocytes and the percentage of eosinophil cells in bronchoalveolar lavage fluid (BALF). YKL-40 mRNA and protein expression levels were detected using quantitative real-time PCR and western blot assays. Enzyme-linked immunosorbent assay (ELISA) was used to detect YKL-40 and eosinophil-related chemokine expression levels in BALF and serum. Lung histology analyses were performed to evaluate the degree of inflammatory cell infiltration around the airway and airway mucus secretion.YKL-40 shRNA significantly inhibited the YKL-40 gene expression in asthmatic mice. In addition, YKL-40 shRNA alleviated eosinophilic airway inflammation, AHR, airway mucus secretion and decreased the levels of YKL-40 in BALF and serum in a murine asthmatic model. The levels and mRNA expression of IL-5, IL-13 in asthmatic mice lung tissues, eotaxin, and GM-CSF in BALF and serum significantly decreased. Bone marrow signaling molecules including IL-5, eotaxin, and GM-CSF were correlated with decreased levels of YKL-40. The study reveals that YKL-40 could be involved in asthma inflammation by altering bone marrow signaling molecules. YKL-40 gene RNA interference could provide new therapeutic strategies for asthma.

YKL-40 as a novel biomarker in cardio-metabolic disorders and inflammatory diseases

Dyslipidaemia is associated with numerous health problems that include the combination of insulin resistance, hypertension and obesity, ie, metabolic syndrome. Although the use of statins to decrease serum low density lipoprotein cholesterol (LDL-C) has been an effective therapeutic in treating atherosclerosis, the persistence of high atherosclerotic risk, ie, residual risk, is notable and is not simply explained as a phenomenon of dyslipidaemia. As such, it is imperative that we identify new biomarkers to monitor treatment and more accurately predict future cardiovascular events. This athero-protective strategy includes the assessment of novel inflammatory biomarkers such as YKL-40. Recent evidence has implicated YKL-40 in patients with inflammatory diseases and cardio-metabolic disorders, making it potentially useful to evaluate disease severity, prognosis and survival. In this review, we summarize role of YKL-40 in the pathogenesis of cardio-metabolic disorders and explore its use as a novel biomarker for monitoring athero-protective therapy.

YKL-40 (Chitinase-3-Like Protein 1) Serum Levels in Aortic Stenosis

BACKGROUND

Identification of novel biomarkers could provide prognostic information and improve risk stratification in patients with aortic stenosis (AS). YKL-40 (chitinase-3-like protein 1), a protein involved in atherogenesis, is upregulated in human calcific aortic valves. We hypothesized that circulating YKL-40 would be elevated and associated with the degree of AS severity and outcome in patients with symptomatic AS.

METHODS

Plasma YKL-40 was analyzed in 2 AS populations, one severe AS (n=572) with outcome measures and one with mixed severity (n=67). YKL-40 expression in calcified valves and in an experimental pressure overload model was assessed.

RESULTS

We found (1) patients with AS had upregulated circulating YKL-40 compared with healthy controls (median 109 versus 34 ng/mL, P<0.001), but levels were not related to the degree of AS severity. (2) High YKL-40 levels (quartile 4) were associated with long-term (median follow-up 4.7 years) all-cause mortality (adjusted hazard ratio, 1.93 [95% CI, 1.37-2.73], P<0.001). (3) YKL-40 protein expression in human calcific valves co-localized with its putative receptor IL-13rα2 in close proximity to valve interstitial cells. (4) Myocardial YKL-40 increased in experimental pressure overload (6-fold in decompensated versus sham mice).

CONCLUSIONS

YKL-40 levels were elevated in AS and associated with mortality but not with other metrics of disease severity including the degree of AS severity. Despite scientific rationale for its role in AS, the clinical utility of circulating YKL-40 as a biomarker is limited. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01794832.

Overexpression of YKL-40 (CHI3L1 gene) in patient fluids may be a potential predictive marker for early detection of comorbidity in non-communicable disease

Predictive biomarkers which can diagnose the onset of non-communicable diseases and the associated comorbid conditions are lacking for clinical utility. Highly sensitive and specific biomarkers for early disease detection and risk stratification may provide timely intervention to patients and prevent secondary complications. However, till the time patients are diagnosed, cellular events and biomolecules get active effecting multiple organs at the same time. This series of events lead to disruption in normal functioning of the organs and their coordinative crosstalk, hence, increase in mortality rate of patients. The primary functional molecules of inflammatory pathways are active in NCDs. YKL-40, an anti-apoptotic molecule in inflammatory pathways, is overexpressed in patient fluids in different organs under diseased conditions. We performed a preliminary network analysis to study YKL-40 co-expression with diagnostic markers: TNNT2/I3 (Cardiac Troponin T/I) for cardiovascular diseases, LCN2 (NGAL) and CKM (Creatinine kinase M-type) in acute kidney injury and HbA1c in type-2-diabetes. It is observed that YKL-40 is actively co-expressed and linked with standard diagnostic markers and may be influencing the pathways active in organ crosstalk. The pathways may be regulating the signaling events in patients with non-communicable diseases leading to comorbidities. We, hence, postulate that if YKL-40 and disease specific pathways influenced are clinically utilized, this will provide the foundation of establishing tailored and specific approach in diagnosis and monitoring non-communicable diseases and predict the onset of comorbid conditions due to phenomenon influencing organ cross talks.

YKL-40 A Sensitive Biomarker for Early Androgenetic Alopecia and Early Hidden Metabolic Syndrome

Background:

Androgenetic alopecia (AGA) is a common dermatological problem, Does the onset of the AGA matters in the general health? YKL 40 may have role in the pathogenesis of early AGA and associated metabolic syndrome (MS). YKL 40, released by many inflammatory cells and its biological role is not well known.

Aim of the Work:

The estimation of serum level of YKL-40 in patients with AGA to detect its role in AGA and MS pathogenesis, onset and severity.

Materials and Methods:

This case–control study, 100 individuals were enrolled in our study; 70 AGA patients and 30 healthy controls. We obtained an informed written consent from each individual prior the participation. AGA was diagnosed clinically, and onset was evaluated as early onset alopecia (by the age of 30 years or earlier), YKL-40 level was measured by ELISA technique.

Results:

Patients showed highly significant higher serum YKL-40 level more than that of the healthy subjects (P < 0.001). There was highly significant increase in YKL-40 level among early onset male and female cases compared to late onset cases (P < 0.001 each). There was significant increase in MS elements in AGA cases than controls (P < 0.05), and highly significant increase in MS associations and severity among early onset male and female cases compared to late onset cases (P < 0.001 each). AGA patients with MS showed highly significant higher serum YKL-40 level more than that without (P < 0.001). There was highly significant increase in YKL-40 level among early onset AGA with MS compared to late onset cases with MS (P < 0.001 each).

Conclusions:

High serum YKL-40 considered not only a biomarker of early onset AGA but also considered a potential sensitive predictor for early onset MS development and severity in patients with early onset AGA.

Prognosis and Reclassification by YKL-40 in Stable Coronary Artery Disease

Background

The inflammatory biomarker YKL‐40 has previously been studied as a potential risk marker in cardiovascular disease. We aimed to assess the prognostic reclassification potential of serum YKL‐40 in patients with stable coronary artery disease.

Methods and Results

The main study population was the placebo group of the CLARICOR (Effect of Clarithromycin on Mortality and Morbidity in Patients With Ischemic Heart Disease) trial. The primary outcome was a composite of acute myocardial infarction, unstable angina pectoris, cerebrovascular disease, and all‐cause mortality. We used Cox proportional hazards regression models adjusted for C‐reactive protein level and baseline cardiovascular risk factors. Improvement in prediction by adding serum YKL‐40 to the risk factors was calculated using the Cox‐Breslow method and c‐statistic. A total of 2200 patients were randomized to placebo, with a follow‐up duration of 10 years. YKL‐40 was associated with an increased risk of the composite outcome (hazard ratio per unit increase in (YKL‐40) 1.13, 95% CI 1.03–1.24, P=0.013) and all‐cause mortality (hazard ratio 1.32, 95% CI 1.17–1.49, P<0.0001). Considering whether a composite‐outcome event was more likely to have, or not have, occurred to date, we found 68.4% of such predictions to be correct when based on the standard predictors, and 68.5% when serum YKL‐40 was added as a predictor. Equivalent results were obtained with c‐statistics.

Conclusions

Higher serum YKL‐40 was independently associated with an increased risk of adverse cardiovascular outcomes and mortality. Addition of YKL‐40 did not improve risk prediction in patients with stable coronary artery disease.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00121550.

Association of YKL-40 with endothelial dysfunction in patients with essential hypertension

Human cartilage glycoprotein 39 (YKL-40) is related with presence and extent of atherosclerosis, which can be a new biomarker of inflammation and endothelial dysfunction. The relationship between YKL-40 and endothelial dysfunction in patients with essential hypertension (EH) has not been intensively investigated. The relationship between serum level of YKL-40 and endothelial dysfunction was evaluated in 60 EH subjects and 50 normal control (NEH) subjects. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of YKL-40. Brachial artery flow-mediated vasodilation (FMD) was used to measure endothelial-dependent nitric oxide-mediated vasodilatory capacity as the function of endothelial index. This study demonstrated that YKL-40 expression was significantly increased ( p < 0.05) in EH subjects compared with NEH subjects. The FMD was significantly impaired in EH subjects compared with NEH subjects. YKL-40 was not only negatively correlated with FMD, but also with carotid artery intima-media thickness (IMT). Multiple liner regression analysis identified that YKL-40 was independent of FMD development. The level of YKL-40 was elevated in EH patients and inversely related with FMD and may be independent of endothelial dysfunction in EH.

Deletion of Chitinase-3-like 1 accelerates stroke development through enhancement of Neuroinflammation by STAT6-dependent M2 microglial inactivation in Chitinase-3-like 1 knockout mice

Chitinase 3-like 1 (Chi3L1) plays a major role in the pathogenesis of inflammatory diseases. We investigated the effect of Chi3L1 knockout on stroke development. Ischemia/reperfusion was induced by middle cerebral artery occlusion (MCAO) in Chi3L1 knockout and wildtype mice. Significantly increased infarct volume and decreased neurological deficit scores at 24 h after ischemia/reperfusion were found in Chi3L1 knockout mice compared to wildtype mice. Moreover, ischemic neuronal cell death was increased in Chi3L1 knockout mice through increased oxidative stress and release of IL-6 and IL-1β but IL-10 and IL-4 were reduced. Furthermore, expression of inflammation-related proteins (iNOS, COX-2, Iba-1, and GFAP) was significantly increased in Chi3L1 knockout mice compared to wildtype. In microglia isolated from MCAO-injured Chi3L1 knockout mice, expression of M1 markers (iNOS, CD86, IL-1β, and IL-6) was increased and M2 markers (Arg1, Mrc1, IL-10, and IL-4Ra) was decreased. In BV-2 cells, knockdown of Chi3L1 increased TNF-α- and INF-γ-induced expression of iNOS, COX-2, and Iba-1, but decreased the expression of Arg1, MRC1, and IL-4 receptor-alpha (IL-4Rα). Expression of IL-4Rα, an important factor of M2 polarization, and its downstream signals p-JAK1, p-JAK3, and p-STAT6, was much reduced in the knockout mice. Additionally, in BV-2 cells, knockdown of Chi3L1 by siRNA Chi3L1 decreased rhTNF-α- and INF-γ-induced expression of IL-4Rα, p-JAK1, p-JAK3, and p-STAT6. Furthermore, treatment with AS1517499 abolished Chi3L1 knockdown-induced reduced IL-4Rα and Arg1 but not CD86 expression. Our results indicate that deletion of Chi3L1 accelerates stroke development through enhancement of neuroinflammation by markedly decreasing STAT6-dependent M2 macrophage polarization.

The serum YKL-40 level is a potential biomarker for OSAHS: a systematic review and meta-analysis

PURPOSE

Several studies have reported that serum YKL-40 level was elevated in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). However, most of these studies had relatively small sample sizes and the results were inconsistent. Therefore, a meta-analysis was conducted to determine the potential role of serum YKL-40 level in OSAHS.

METHODS

A systematic literature search was performed in several databases to identify eligible studies involving the relationship between serum YKL-40 level and OSAHS. The standardized mean difference (SMD) with its 95% confidence interval (CI) was calculated to determine the effect sizes.

RESULTS

Five eligible articles were extracted in this meta-analysis. The pooled results demonstrated that the serum YKL-40 level was significantly higher in OSAHS patients compared with their non-OSAHS controls (SMD 1.03, 95% CI 0.46, 1.59, I² = 87%, P = 0.0004). The subgroup analysis showed that Asian (SMD 1.81, 95% CI 1.41, 2.21, I² = 0%, P < 0.00001) and Caucasian (SMD 0.67, 95% CI 0.39, 0.96, I² = 0%, P < 0.00001) patients with OSAHS had higher serum YKL-40 levels than their non-OSAHS controls. YKL-40 level in serum was increased in OSAHS patients with BMI < 28 (SMD 1.81, 95% CI 1.41, 2.21, I² = 0%, P < 0.00001), as well as in patients with BMI ≥ 28 (SMD 0.57, 95% CI 0.33, 0.81, I² = 0%, P < 0.00001). In addition, OSAHS patients with cardiac complications had a higher serum YKL-40 level compared with those patients without cardiac complications (SMD 0.80, 95% CI 0.32, 1.28, I² = 67%, P = 0.001).

CONCLUSIONS

This study indicates that OSAHS patients have higher serum YKL-40 level, which may serve as a potential biomarker for OSAHS diagnosis and monitoring.

Elevated serum YKL40 level is a predictor of MACE during the long-term follow up in hypertensive patients

Background: YKL-40 (human cartilage glycoprotein 39, chitinase-3-like protein 1) is an inflammatory marker secreted mainly by macrophages and has distinctive roles on extracellular matrix remodeling, macrophage maturation, adhesion, and migration. Despite the presence of robust data suggesting the association of YKL-40 with variety of cardiovascular diseases (CV), there is no study up to date evaluating the role of YKL-40 on the long-term prognosis in patients with hypertension (HT).Methods: A single center, prospective, observational cohort study that included 327 consecutive hypertensive patients which were presented to a cardiology outpatient clinic. Patients were followed up for 7.89 ± 0.12 years. Primary outcome of the study was the occurrence of major cardiovascular outcomes (MACE) defined as all-cause mortality, new onset heart failure (HF), and coronary artery disease (CAD) requiring revascularization.Results: A total of 135 patients constituted the final study population [mean age: 52.4 ± 10.2, female: 63 (46%)]. A total of 28 (20.7%) patients had MACE during the follow up. Cox regression analysis revealed that age (HR: 1.046, 1.016-1.093 CI 95%, p = .026), diabetes (HR: 2.278, 1.026-5.057 CI 95%, p = .043), and YKL-40 level (HR: 1.019, 1.013-1.026 CI 95%, p = .005) significantly predicted MACE. We found that sensitivity and specificity of YKL-40 > 93.5 for predicting MACE was 71.4% and 65%, respectively with an area under curve (AUC) 0.723 (0.617-0.828 CI 95%, p < .001)Conclusion: Elevated serum YKL-40 level predicted MACE in hypertensive patients during a long-term follow up.

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.

Serum YKL-40 predicts long-term outcome in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

Serum YKL-40, a potential inflammatory marker, is greatly increased at the early stage of ST-segment elevation myocardial infarction (STEMI). Here, we hypothesized that YKL-40 levels at admission could predict the long-term outcomes after STEMI.A total of 324 patients with acute STEMI undergoing primary percutaneous coronary intervention (PCI) were consecutively enrolled and followed for 24 months. The baseline clinical and procedural data were recorded, and serum YKL-40 levels at admission were measured using ELISA method. The endpoint of interest was major adverse cardiac event (MACE), including all-cause death, recurrent myocardial infarction, and hospitalization for heart failure.Patients with elevated serum YKL-40 levels (≥126.8 ng/mL) were more likely to be older and smoker and to present with type 2 diabetes, advanced Killip class, multivessel disease and intra-aortic balloon pump, with increased levels of admission glucose, triglyceride, and high-sensitivity C-reactive protein and decreased level of high-density lipoprotein cholesterol. During the follow-up period, the incidence of MACE was notably higher in the high than in the low YKL-40 groups (28.4% vs 11.1%, P < .001). Kaplan-Meier curve showed that elevated YKL-40 levels were associated with reduced MACE-free survivals (log-rank P < .001). In multivariate Cox regression analysis, we found that high serum YKL-40 level was an independent predictor of MACE after controlling for clinical and angiographic variables (hazard ratio: 1.65, 95% confidence interval: 1.14-2.39, P = .008).The results of our study indicate that serum YKL-40 may be used as a biomarker to predict the long-term outcome after PCI in patients with STEMI.

Assessment of potential biomarkers of atherosclerosis in Indian patients with type 2 diabetes mellitus

Background & objectives:

Various biological markers of subclinical atherosclerosis have been proposed to predict cardiovascular events in patients with diabetes mellitus (DM). However, there are only a few clinical studies assessing the role of invasive biomarkers [CD-36, peroxisome proliferator-activated receptor gamma (PPAR-γ) and YKL-40] in Indian patients with type 2 DM (T2DM). Hence, the present study was conducted to assess protein levels and gene expression of CD-36, PPAR-γ and YKL-40 in patients with T2DM and compare that with hypertensive and healthy controls.

Methods:

All the participants were subjected to medical history, anthropometric measurements and biochemical and biomarker (ELISA and real-time polymerase chain reaction) estimations. The study groups consisted of patients with T2DM (>5 yr) with hypertension (n=55), patients with T2DM (<2 yr) without hypertension (n=28), hypertensive controls (n=31) and healthy controls (n=30).

Results:

Gene expressions of YKL-40 and CD36 were significantly higher in patients with T2DM (>5 yr) with hypertension compared to healthy controls (P=0.006). In addition, a significant increase in serum levels of sCD36, PPAR-γ and YKL-40 was observed in patients with T2DM (>5 yr) with hypertension compared to healthy controls (P< 0.05). Serum levels as well as gene expression of CD36 showed significant correlation with serum levels as well as gene expression of PPAR-γ (ρ=0.45 and ρ=0.51; P< 0.001), respectively.

Interpretation & conclusions:

CD36 and YKL-40 may be potential inflammatory biomarkers for early onset of atherosclerosis in patients with T2DM.

YKL-40 is highly expressed in the epicardial adipose tissue of patients with atrial fibrillation and associated with atrial fibrosis

Background

YKL-40 (CHI3L1) is a novel biomarker for inflammation, tissue remodeling, and fibrosis, as well as cardiovascular diseases. We investigated the association between YKL-40 expression in epicardial adipose tissue (EAT) and atrial fibrosis in patients with atrial fibrillation (AF).

Methods

Blood samples, subcutaneous adipose tissue (SAT), paracardial adipose tissue (PAT), EAT, and adjacent atrial myocardium were acquired from patients receiving coronary artery bypass grafts. The patients were divided into the AF group (n = 28) and the sinus rhythm (SR) group (n = 36).

Results

We did not detect a significant difference in the serum YKL-40 levels in the SR and AF groups (P = 0.145). Quantitative real-time PCR showed that YKL-40 (CHI3L1) mRNA levels in the EAT were significantly higher than in the SAT or PAT of AF patients, or the EAT of SR patients (All P < 0.001). We found similar results for YKL-40 protein levels by immunohistochemistry. Masson staining showed significantly more fibrosis in AF patients than in SR patients (P < 0.001). Western blotting indicated that AF patients had significantly higher expression of collagen I (P = 0.039). We found a linear relationship between YKL-40 mRNA expression and the collagen volume fraction of the atrial myocardium (y = 3.576x + 26.205, P < 0.001). Multivariate linear regression analysis revealed that body mass index is an independent risk factor for YKL-40 expression in EAT (β = 0.328, P = 0.011).

Conclusions

YKL-40, which is highly expressed in the EAT of patients with AF, is affected by body mass index and associated with atrial fibrosis, which may contribute to the development of AF.

Serum hs-CRP, YKL-40 and brain-derived neurotrophic factor (BDNF) associated biomarkers in non-dipper hypertension profile?

Background: Twenty-four hours dynamic blood pressure (BP) behaviour displays dipper profile defined as nocturnal systolic BP (SBP) reduction>10% compared to daytime. Non-dipper profile, nocturnal absence of SBP fall, associates an increased cardiovascular risk. We investigated the concomitant association of inflammatory bio-markers - high-sensitivity- C-reactive protein (hs-CRP), Human Chitinase3-like1 (YKL-40) and autonomic nervous system (total brain-derived neurotrophic factor, BDNF) with respect to non-dipping blood pressure status.

Material and method: Using 24h automatic BP measurements, 80 known hypertensive patients were divided into two groups: dipper group included fifty-one dipper patients (age 55.6 ±13.5 years) and non-dipper group consisted of 29 non-dipper subjects (62.07±12.03 years). Serum levels of hs-CRP were evaluated with enhanced immunoturbidimetric assay. Plasma levels of YKL-40 were measured by commercial sandwich ELISA using microplate coated with a monoclonal antibody for CHI3L1. Plasma levels of total BDNF were determined using quantitative sandwich enzyme-linked immunoassay. Statistical analysis of obtained data was performed.

Results: In the non-dipper group, a significant positive association with age over 60 years, hs-CRP values above 1.90 mg/dl was observed along with increased mean values of YKL-40. Non-dipper status is independently and statistically significantly associated with elevated levels of hs-CRP (OR: 3.248, 95% CI: 1.022-10.317, p=0.046) in multivariate odds ratio analysis. No statistically significant positive association between a median total BDNF plasma level of 1430 pg/ml and the non-dipper hypertension profile was identified.

Conclusion: Our study demonstrated that patients over 60 years, in particular, have a higher probability to present a non-dipping pattern of hypertension. hs-CRP and YKL-40 values are more likely to increase in the non-dipping hypertensive patients, and hs-CRP values above 1.9 mg/dl can identify the presence of a non-dipper blood pressure profile.

YKL-40: A biomarker for early nephropathy in type 2 diabetic patients and its association with inflammatory cytokines

Diabetic Nephropathy (DN) is an important cause of morbidity and death amongst diabetes. Persistent micro and macroalbuminuria are well known predictors of DN leading to progressive end-stage renal disease. However, albuminuria has several limitations. Increasing evidences show that YKL-40 is highly expressed in variety of inflammatory diseases and also recognized as a non-invasive prognostic biomarker for inflammation. In the present study, we measured plasma YKL-40 levels in different stages of albuminuria and assessed its diagnostic accuracy as a biomarker for DN and correlated with different families of circulatory cytokines. A total of 306 subjects were recruited and divided into three groups [Group-I, control (n = 83), Group-II, Normoalbuminuria (n = 81), Group-III, DN (n = 142)]. Group-III is further subdivided into: Group-IIIa, microalbuminuria (n = 73), Group-IIIb, macroalbuminuria (n = 69). The median levels of YKL-40 (p = 0.001) showed a marked stepwise increase from normo to macroalbuminuria and positively correlated with eGFR. The AUC_ROC for YKL-40 was found to be high [0.95; (95% CI: 0.88-1.0)], when compared to other acute phase markers. Plasma YKL-40 showed a positive correlation with LIGHT/TNFSF14, sIL-6Ra, gp130/sIL-6Rβ, IFN-β, IL-8, TNFSF14, sCD-30 and eGFR meanwhile a negative correlation with TWEAK/TNFSF12, IL-7 like cytokine and IFN-λ2. Plasma YKL-40 could be a potential biomarker for early diagnosis of incipient DN among South Indian population.

YKL-40 levels increase with declining ankle-brachial index and are associated with long-term cardiovascular mortality in peripheral arterial disease patients

BACKGROUND AND AIMS

YKL-40 is an inflammatory marker secreted by macrophages and is expressed in atherosclerotic plaques. YKL-40 increases in coronary artery disease (CAD) with poor coronary collateral vessel development. Higher levels are linked to reduced survival in CAD patients. Studies evaluating YKL-40 in patients with peripheral arterial disease (PAD) are scarce. This study aims to elucidate a possible link between YKL-40 and PAD severity as well as cardiovascular long-term mortality.

METHODS

YKL-40 was measured at baseline in 365 elderly PAD patients (age 69 ± 10.4, 33.7% women, Fontaine stage I-II) by bead-based multiplex assay. Patients were followed for seven years to assess long-term cardiovascular and all-cause survival by Kaplan-Meier and Cox regression.

RESULTS

YKL-40 levels were associated with declining ankle-brachial index (ABI) in PAD patients without Moenckeberg's mediasclerosis (R = -0.189, p=0.002). PAD patients with mediasclerosis exhibited higher YKL-40 levels (p=0.002). Baseline YKL-40 levels were significantly associated with cardiovascular mortality (HR 1.52 (1.21-1.91), p < 0.001) and all-cause mortality (HR 1.45 (1.20-1.75), p < 0.001) over a seven-year observation period. After multivariable adjustment for gender, patient age, known carotid artery disease, known coronary artery disease, smoking status, systolic blood pressure, HbA_1c, low density lipoprotein cholesterol, estimated glomerular filtration rate, aspartate aminotransferase, and C-reactive protein, YKL-40 remained significantly associated with cardiovascular (HR 1.34 (1.02-1.75), p=0.033) and all-cause mortality (HR 1.25 (1.01-1.55), p=0.039).

CONCLUSIONS

Increased YKL-40 levels are independently associated with poor long-term cardiovascular survival in peripheral arterial disease patients. Furthermore, YKL-40 correlates with patients' ABI in PAD in the absence of mediasclerosis.

Plasma YKL-40 Elevation on Admission and Follow-Up Is Associated with Diastolic Dysfunction and Mortality in Patients with Acute Myocardial Infarction

Objective

The aim of the study was to determine an association between the plasma YKL-40 level and echocardiographic left ventricle systolic and diastolic function parameters in patients with acute myocardial infarction.

Subjects and Methods

The study included 46 patients with acute myocardial infarction. Serum brain natriuretic protein (BNP) and YKL-40 levels were analyzed on admission and after one month. Left ventricle systolic and diastolic functions and Tei index were computed by transthoracic echocardiography.

Results

Plasma YKL-40 was significantly higher in patients with acute myocardial infarction (AMI) (101.7 μg/L versus 34 μg/L, resp., p < 0.001) and remained higher than in healthy subjects after one month. The levels of YKL-40 on admission were correlated with log BNP on admission (r=0.41, p=0.004), Tei index (r=0.44, p=0.002), left atrium volume index (r=0.32, p=0.02), and mitral septal annular E/e′ (r=0.44, p=0.003). Death was more frequently observed in patients with plasma YKL-40 above the median value than in those with plasma YKL-40 below the median value (p=0.001; OR = 13.6 (2.5–72.3)).

Conclusion

YKL-40 elevations in patients with AMI remain at least one month and are associated with serum BNP elevations, diastolic dysfunction, and long-term increased overall mortality. It has prognostic importance in patients with AMI.

New Insights Into the Relationship Between Chitinase-3-Like-1 and Asthma

PURPOSE OF REVIEW

CHI3L1 (also known as YKL-40), a member of "mammalian chitinase-like proteins," is a serum protein lacking enzymatic activity. Although the protein is highly conserved in mammals, a consensus regarding its role in human pathologies is currently lacking. In an attempt to shed light on the many physiological functions of the protein, specifically with regard to asthma, a comprehensive overview of recent studies is provided.

RECENT FINDINGS

In asthma, CHI3L1 is secreted from macrophages and airway epithelial cells through an IL-13 related mechanism. Th2-associated inflammatory responses due to allergen exposure, resulting in airway hyper-responsiveness and smooth muscle contraction, play a role in tissue remodeling. The importance of CHI3L1 in initiation and development of asthma is not limited to its involvement in highly orchestrated events of inflammatory cytokines but further research is needed for further elucidation. Levels of the protein are associated with severity for numerous pathologies, including asthma, suggesting limited specificity as a biomarker.

Circulating miRNA-24 and its target YKL-40 as potential biomarkers in patients with coronary heart disease and type 2 diabetes mellitus

Type 2 diabetes mellitus (DM2) is associated with cardiovascular complications and is characterized by high levels of YKL-40, an inflammatory glycoprotein involved in endothelial dysfunction. We investigated the predictive potential of circulating miR-24 in coronary heart diseases (CHD) DM2 patients with CHD, and control subjects. Blood samples were taken from 94 subjects of both genders, and divided over three groups as follows; patients with CHD, patients with DM2 and CHD, and control subjects. Both miR-24 (using real time PCR) and routine parameters were measured. Using bioinformatic analysis and luciferase assays, we found that miR-24 has high complementarity and a high degree of species conservation with respect to the binding sites within the 3′ UTR of the YKL-40 mRNA. The expression levels of circulating miR-24, determined by quantitative real time PCR, were significantly decreased in peripheral blood of DM2-CHD and CHD patients compared with controls. Furthermore, miR-24 strongly associated with DM2-CHD, negatively correlated with YKL-40 in DM2-CHD and DM2 patients after conducting multiple regression analysis. These results provide a novel regulatory mechanism of circulating miR-24 in regulating YKL-40 levels in DM2-CHD, may serve as a biomarker for predicting patients with DM2 and CHD.

Extracellular matrix markers and risk of myocardial infarction: The HUNT Study in Norway

Aims Extracellular matrix remodelling may influence atherosclerotic progression and plaque stability. We hypothesized that evaluation of extracellular matrix markers, with potentially different roles during atherogenesis, could provide information on underlying mechanisms and risk of myocardial infarction (MI) in apparently healthy individuals. Methods We conducted a case-control study nested within the population-based HUNT2 cohort in Norway. A total of 58,761 men and women, free of known cardiovascular disease, were followed for a first MI. During 11.3 years of follow-up, 1587 incident MIs were registered, and these cases were compared with 3959 age- and sex-matched controls. Circulating levels of the ECM proteins CD147 (ECM metalloproteinase inducer; EMMPRIN), cartilage oligomeric matrix protein (COMP: thrombospondin-5) and YKL-40 (chitinase-3-like-1) were measured by enzyme immunoassays. Results We found an inverse association between COMP (quartile (Q) 4 vs. Q1: hazard ratio 0.81 (95% confidence interval: 0.67-0.98)) and YKL-40 (Q4 vs. Q1: hazard ratio 0.77 (0.62-0.95)) with incidence of MI after full multivariable adjustment. Serum CD147 was not associated with MI risk in adjusted analysis. Conclusion High levels of COMP and YKL-40 were associated with lower risk of incident MI, suggesting a potential beneficial role in promoting plaque stability in individuals without incident cardiovascular disease.

Extracellular matrix proteomics identifies molecular signature of symptomatic carotid plaques

BACKGROUND. The identification of patients with high-risk atherosclerotic plaques prior to the manifestation of clinical events remains challenging. Recent findings question histology- and imaging-based definitions of the “vulnerable plaque,” necessitating an improved approach for predicting onset of symptoms.

METHODS. We performed a proteomics comparison of the vascular extracellular matrix and associated molecules in human carotid endarterectomy specimens from 6 symptomatic versus 6 asymptomatic patients to identify a protein signature for high-risk atherosclerotic plaques. Proteomics data were integrated with gene expression profiling of 121 carotid endarterectomies and an analysis of protein secretion by lipid-loaded human vascular smooth muscle cells. Finally, epidemiological validation of candidate biomarkers was performed in two community-based studies.

RESULTS. Proteomics and at least one of the other two approaches identified a molecular signature of plaques from symptomatic patients that comprised matrix metalloproteinase 9, chitinase 3-like-1, S100 calcium binding protein A8 (S100A8), S100A9, cathepsin B, fibronectin, and galectin-3-binding protein. Biomarker candidates measured in 685 subjects in the Bruneck study were associated with progression to advanced atherosclerosis and incidence of cardiovascular disease over a 10-year follow-up period. A 4-biomarker signature (matrix metalloproteinase 9, S100A8/S100A9, cathepsin D, and galectin-3-binding protein) improved risk prediction and was successfully replicated in an independent cohort, the SAPHIR study.

CONCLUSION. The identified 4-biomarker signature may improve risk prediction and diagnostics for the management of cardiovascular disease. Further, our study highlights the strength of tissue-based proteomics for biomarker discovery.

FUNDING. UK: British Heart Foundation (BHF); King’s BHF Center; and the National Institute for Health Research Biomedical Research Center based at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London in partnership with King’s College Hospital. Austria: Federal Ministry for Transport, Innovation and Technology (BMVIT); Federal Ministry of Science, Research and Economy (BMWFW); Wirtschaftsagentur Wien; and Standortagentur Tirol.

Predictors for major cardiovascular outcomes in stable ischaemic heart disease (PREMAC): statistical analysis plan for data originating from the CLARICOR (clarithromycin for patients with stable coronary heart disease) trial

BACKGROUND

The purpose of the predictors for major cardiovascular outcomes in stable ischaemic heart disease (PREMAC) study is exploratory and hypothesis generating. We want to identify biochemical quantities which-conditionally on the values of available standard demographic, anamnestic, and biochemical data-may improve the prediction of cardiovascular outcomes and/or death in patients suffering from stable ischaemic heart disease. The candidate biochemical quantities include N-terminal pro-B-type natriuretic peptide, YKL-40, osteoprotegerin, high-sensitive assay cardiac troponin T (hs-cTnT), pregnancy-associated plasma protein-A (PAPP-A), cathepsin B, cathepsin S, soluble TNF receptor 1 and 2, neutrophil gelatinase-associated lipocalin, endostatin, and calprotectin. As an extra objective, we also want to assess if skewness in these predictors may explain why the clarithromycin for patients with stable coronary heart disease (CLARICOR) trial found increased all-cause and cardiovascular (CV) mortality on a brief clarithromycin regimen compared with placebo.

METHODS

Baseline data were obtained from the hospital files at five cardiology clinics covering the Copenhagen area. The CLARICOR trial included data from 4372 stable coronary artery disease patients recruited among such patients alive and diagnosed with acute myocardial infarction or unstable angina pectoris during 1993 to 1999 in Copenhagen and randomised during October 1999 to April 2000 to the CLARICOR trial of 14 days clarithromycin versus placebo.Initial follow-up lasted for 2.6 years, during which outcomes were collected through hospital and death registries and assessed by an adjudication committee. Corresponding register data later showed to produce similar results. The adjudicated outcomes were therefore replaced and augmented by register data on outcomes to cover 10 years of follow-up. Biochemical marker data were obtained from analysis of serum from the CLARICOR bio-bank collected at randomisation and stored at -80° C.Using Cox proportional hazard method, we will identify among the candidate biochemical quantities those which are significant predictors when used alone and in combination with the standard predictors as defined in the present study.

DISCUSSION

Patients who became stable during the period 1993 to 1999 and died before October 1999 are missing. The data from the placebo patients are nevertheless useful to identify new prognostic biomarkers in patients with stable coronary artery disease, and data from both trial groups are useful to assess important potential skewness between randomised groups. However, due to the potential selection bias, we do not feel that it is advisable to try to rank identified biochemical predictors relative to each other nor to use the results for predictive purposes.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00121550 Date of registration 13 July 2005Date of enrolment of first participant 12 October 1999.

Chitinase-3-like protein-1 (YKL-40) as a marker of endothelial dysfunction in obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a highly prevalent disorder affecting 15-24% of adults and triples the risk for hypertension independent of other risk factors. The exact mechanisms of endothelial dysfunction and variable susceptibility to hypertension in OSA are not entirely clear. No biomarker to date has been found to be associated with hypertension in OSA. Chitinase-3-like protein-1(YKL-40) is a circulating moiety with roles in injury, repair and angiogenesis that is dysregulated in atherosclerosis and correlates with increased cardiovascular morbidity and mortality. We sought to determine the role of YKL-40, as a biomarker, for endothelial dysfunction and hypertension in OSA.

METHODS

All subjects underwent polysomnography for suspected sleep-disordered breathing. Endothelial-dependent vasodilatory capacity was assessed using flow-mediated vasodilation (FMD). YKL-40 was measured in plasma using ELISA methodology.

RESULTS

We studied 95 subjects in four groups according to OSA and hypertension status. FMD was markedly impaired in hypertensive OSA (8.0% ± 0.5 vasodilation) compared to normotensive OSA (13.5% ± 0.5, P <0.0001) and non-OSA with hypertension (10.5% ± 0.8, P <0.01) and without hypertension (16.1% ± 1.0, P <0.0001). YKL-40 was significantly elevated only in hypertensive OSA compared to other three groups and had a negative correlation with FMD (r=-0.37, P = 0.0008). Receiver operating characteristic (ROC) curve analysis for YKL-40 in predicting endothelial dysfunction had a sensitivity of 71% and a specificity of 64% with AUC = 0.68, 0.57 to 0.80, P = 0.004.

CONCLUSIONS

Elevated circulating levels of YKL-40 are observed in only hypertensive OSA and have a significant negative correlation with endothelial function. This specificity suggests YKL-40 could be a potential biomarker for endothelial dysfunction in OSA.

Evaluation of potential circulating biomarkers for prediction of response to chemoradiation in patients with glioblastoma

Surgery followed by chemoradiation and adjuvant chemotherapy is standard of care for patients with a glioblastoma (GBM). Due to its limited benefit, an upfront method to predict dismal outcome would prevent unnecessary toxic treatment. We searched for a predictive blood derived biomarker in a cohort of 55 patients with GBM. Increasing age (HR 1.03, 95 % CI 1.01–1.06), and postoperative tumor residue (HR 1.07, 95 % CI 1.02–1.15) were independently associated with unfavourable progression free survival (PFS) in these patients. Corticosteroid use before start of chemoradiaton was strongly predictive for outcome (HR 3.26, 95 % CI 1.67–6.39) with a mean PFS and OS in patients using corticosteroids of 7.3 and 14.6 months, versus 16.1 and 21.6 months in patients not using corticosteroids (p = 0.0005, p < 0.0067 respectively). Despite earlier reports, blood concentrations of YKL-40, Fetuin-a and haptoglobin were not predictive for response. In addition, serum peptide profiles, determined by MALDI-TOF mass spectroscopy, were not predictive as well. In conclusion, further biomarker discovery studies are needed to predict treatment outcome for patients with GBM in the near future.

Low YKL-40 in chronic heart failure may predict beneficial effects of statins: analysis from the controlled rosuvastatin multinational trial in heart failure (CORONA)

CONTEXT AND OBJECTIVE

To evaluate if YKL-40 can provide prognostic information in patients with ischemic heart failure (HF) and identify patients who may benefit from statin therapy.

MATERIALS AND METHODS

The association between serum YKL-40 and predefined outcome was evaluated in 1344 HF patients assigned to rosuvastatin or placebo.

RESULTS

YKL-40 was not associated with outcome in adjusted analysis. In YKL-40 tertile 1, an effect on the primary outcome (HR 0.50, p = 0.006) and CV death (HR 0.54, p = 0.040) was seen by rosuvastatin in adjusted analysis.

CONCLUSIONS

A beneficial modification of outcome was observed with statin therapy in patients with low YKL-40 levels.

Increased serum YKL-40 level is associated with the presence and severity of metabolic syndrome

Objective:

Metabolic syndrome (MS) is defined by a cluster of interdependent physiological, biochemical, and clinical risk factors and linked to a state of chronic inflammation. YKL-40 is known as an inflammatory glycoprotein, which is secreted by various cell lines during inflammation. Thus, we aimed to assess the association of serum YKL-40 levels with the presence and severity of MS.

Methods:

In this prospective cross-sectional study, a total of 177 consecutive patients [n=114 MS present and n=63 MS absent] were enrolled. MS was defined according to National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. Serum YKL-40 and hs-CRP levels were measured for all participants.

Results:

Serum YKL-40, hs-CRP and white blood cell count (WBC) were significantly higher in the MS present group (p<0.05). There was a graded relationship between increasing number of MS components and serum YKL-40 level (p<0.05). In addition, serum YKL-40 level was positively correlated with hs-CRP level (r=0.467, p<0.001) and WBC count (r=0.251, p=0.001). In multivariable regression analysis, serum YKL-40 [1.022 (1.011–1.033), p<0.001] and hs-CRP [1.346 (1.111–1.632), p=0.002] were remained as independent predictors for the presence of MS. In the ROC curve analysis, using a cut-off level of 147.0, YKL-40 well predicted the presence of MS with a sensitivity of 73.7% and specificity of 69.8% (AUC: 0.785; 95% CI: 0.718–0.853, p<0.001).

Conclusion:

In this study, we demonstrated that serum YKL-40 level was significantly associated with the presence of MS. According to these findings, we concluded that serum YKL-40 may be a novel and useful indicator for MS. (Anatol J Cardiol 2016; 16: 953-8)

Role of inflammatory marker YKL-40 in the diagnosis, prognosis and cause of cardiovascular and liver diseases

This review summarizes present evidence for the role of YKL-40 in the diagnosis, prognosis and cause of cardiovascular and alcoholic liver disease. The question of whether YKL-40 is merely a marker or a causal factor in the development of cardiovascular and liver disease is addressed, with emphasis on the Mendelian randomization design. The Mendelian randomization approach uses genetic variants associated with lifelong high plasma YKL-40 levels that are largely unconfounded and not prone to reverse causation. Thus, the approach mimics a controlled double-blind randomized trial, but it uses genetic variants rather than a drug and placebo, and like a blinded trial, it allows inference about causality. Moreover, the review also covers background on the molecular biology and functions of YKL-40, YKL-40 levels in healthy individuals and reference range, and the role of YKL-40 as a biomarker of cardiovascular and alcoholic liver disease. YKL-40 is a plasma protein named after its three N-terminal amino acids, Y (tyrosine), K (lysine) and L (leucine), and its molecular weight of 40 kDa. It is produced by local inflammatory cells in inflamed tissues, such as lipid-laden macrophages inside the vessel wall and perhaps also hepatic stellate cells. Observational studies show that plasma YKL-40 levels are elevated in patients with cardiovascular and liver disease and are associated with disease severity and prognosis. Furthermore, elevated plasma YKL-40 levels in apparently healthy individuals are associated with a 2-fold increased risk of future ischemic stroke and venous thromboembolism, but not with myocardial infarction, suggesting that YKL-40 could play a role in the formation of embolisms rather than atherosclerosis per se. Further, elevated YKL-40 levels combined with excessive alcohol consumption are associated with 10-years risk of alcoholic liver cirrhosis of up to 7%, suggesting that YKL-40 can be used as a strong noninvasive marker of predicting alcoholic liver cirrhosis. Importantly, in Mendelian randomization studies, genetically elevated plasma YKL-40 levels were not associated with risk of cardiovascular and alcoholic liver disease, thus suggesting that plasma YKL-40 does not play a causal role in the development of these diseases. Despite this, plasma YKL-40 levels may play a role in disease progression after diagnosis, and inhibition of YKL-40 activity might be a novel therapy in some cardiovascular and liver diseases.