Plasma levels of the proinflammatory chitin-binding glycoprotein YKL-40, variation in the chitinase 3-like 1 gene (CHI3L1), and incident cardiovascular events

Cognitive and inflammatory heterogeneity in severe mental illness: Translating findings from blood to brain

Recent findings link cognitive impairment and inflammatory-immune dysregulation in schizophrenia (SZ) and bipolar (BD) spectrum disorders. However, heterogeneity and translation between the periphery and central (blood-to-brain) mechanisms remains a challenge. Starting with a large SZ, BD and healthy control cohort (n = 1235), we aimed to i) identify candidate peripheral markers (n = 25) associated with cognitive domains (n = 9) and elucidate heterogenous immune-cognitive patterns, ii) evaluate the regulation of candidate markers using human induced pluripotent stem cell (iPSC)-derived astrocytes and neural progenitor cells (n = 10), and iii) evaluate candidate marker messenger RNA expression in leukocytes using microarray in available data from a subsample of the main cohort (n = 776), and in available RNA-sequencing deconvolution analysis of postmortem brain samples (n = 474) from the CommonMind Consortium (CMC). We identified transdiagnostic subgroups based on covariance between cognitive domains (measures of speed and verbal learning) and peripheral markers reflecting inflammatory response (CRP, sTNFR1, YKL-40), innate immune activation (MIF) and extracellular matrix remodelling (YKL-40, CatS). Of the candidate markers there was considerable variance in secretion of YKL-40 in iPSC-derived astrocytes and neural progenitor cells in SZ compared to HC. Further, we provide evidence of dysregulated RNA expression of genes encoding YKL-40 and related signalling pathways in a high neuroinflammatory subgroup in the postmortem brain samples. Our findings suggest a relationship between peripheral inflammatory-immune activity and cognitive impairment, and highlight YKL-40 as a potential marker of cognitive functioning in a subgroup of individuals with severe mental illness.

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.

Associations of circulating proteins with lipoprotein profiles: proteomic analyses from the OmniHeart randomized trial and the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Within healthy dietary patterns, manipulation of the proportion of macronutrient can reduce CVD risk. However, the biological pathways underlying healthy diet-disease associations are poorly understood. Using an untargeted, large-scale proteomic profiling, we aimed to (1) identify proteins mediating the association between healthy dietary patterns varying in the proportion of macronutrient and lipoproteins, and (2) validate the associations between diet-related proteins and lipoproteins in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

In 140 adults from the OmniHeart trial, a randomized, cross-over, controlled feeding study with 3 intervention periods (carbohydrate-rich; protein-rich; unsaturated fat-rich dietary patterns), 4,958 proteins were quantified at the end of each diet intervention period using an aptamer assay (SomaLogic). We assessed differences in log2-transformed proteins in 3 between-diet comparisons using paired t-tests, examined the associations between diet-related proteins and lipoproteins using linear regression, and identified proteins mediating these associations using a causal mediation analysis. Levels of diet-related proteins and lipoprotein associations were validated in the ARIC study (n = 11,201) using multivariable linear regression models, adjusting for important confounders.

RESULTS

Three between-diet comparisons identified 497 significantly different proteins (protein-rich vs. carbohydrate-rich = 18; unsaturated fat-rich vs. carbohydrate-rich = 335; protein-rich vs. unsaturated fat-rich dietary patterns = 398). Of these, 9 proteins [apolipoprotein M, afamin, collagen alpha-3(VI) chain, chitinase-3-like protein 1, inhibin beta A chain, palmitoleoyl-protein carboxylesterase NOTUM, cathelicidin antimicrobial peptide, guanylate-binding protein 2, COP9 signalosome complex subunit 7b] were positively associated with lipoproteins [high-density lipoprotein (HDL)-cholesterol (C) = 2; triglyceride = 5; non-HDL-C = 3; total cholesterol to HDL-C ratio = 1]. Another protein, sodium-coupled monocarboxylate transporter 1, was inversely associated with HDL-C and positively associated with total cholesterol to HDL-C ratio. The proportion of the association between diet and lipoproteins mediated by these 10 proteins ranged from 21 to 98%. All of the associations between diet-related proteins and lipoproteins were significant in the ARIC study, except for afamin.

CONCLUSIONS

We identified proteins that mediate the association between healthy dietary patterns varying in macronutrients and lipoproteins in a randomized feeding study and an observational study.

TRIAL REGISTRATION

NCT00051350 at clinicaltrials.gov.

Association of Kidney Tubule Biomarkers With Cardiac Structure and Function in the Multiethnic Study of Atherosclerosis

Markers of glomerular disease, estimated glomerular filtration rate (eGFR) and albuminuria, are associated with cardiac structural abnormalities and incident cardiovascular disease (CVD). We aimed to determine whether biomarkers of kidney tubule injury, function, and systemic inflammation are associated with cardiac structural abnormalities. Among 393 Multi-Ethnic Study of Atherosclerosis participants without diabetes, CVD, or chronic kidney disease, we assessed the association of 12 biomarkers of kidney tubule injury, function, and systemic inflammation with the left ventricular mass/volume ratio (LVmvr) and left ventricular ejection fraction (LVEF) on cardiac magnetic resonance imaging using linear regression. The average age was 60 ± 10 years; 48% were men; mean eGFR was 96±16 ml/min/1.73 m2; mean LVmvr was 0.93±0.18 g/ml, and mean LVEF was 62±6%. Each twofold greater concentration of plasma soluble urokinase plasminogen activator receptor was associated with a 0.04 g/ml (95% confidence interval [CI] 0.01 to 0.08 g/ml) higher LVmvr and 2.1% (95% CI 0.6 to 3.5%) lower LVEF, independent of risk factors for CVD, eGFR, and albuminuria. Each twofold greater plasma monocyte chemoattractant protein 1 was associated with higher LVmvr with a similar coefficient to that of plasma soluble urokinase plasminogen activator receptor. Each twofold greater concentration of plasma chitinase-3-like protein 1 and urine alpha-1-microglobulin was associated with a 1.1% (95% CI 0.4 to 1.7%) and 1.2% (95% CI 0.2 to 2.2%) lower LVEF, respectively. In conclusion, abnormal kidney tubule health may lead to cardiac dysfunction above and beyond eGFR and albuminuria.

Genetic Markers of Insulin Resistance and Atherosclerosis in Type 2 Diabetes Mellitus Patients with Coronary Artery Disease

Type 2 diabetes mellitus (T2DM) is characterized by impaired insulin secretion on a background of insulin resistance (IR). IR and T2DM are associated with atherosclerotic coronary artery disease (CAD). The mechanisms of IR and atherosclerosis are known to share similar genetic and environmental roots. Endothelial dysfunction (ED) detected at the earliest stages of IR might be the origin of atherosclerosis progression. ED influences the secretion of pro-inflammatory cytokines and their encoding genes. The genes and their single nucleotide polymorphisms (SNPs) act as potential genetic markers of IR and atherosclerosis. This review focuses on the link between IR, T2DM, atherosclerosis, CAD, and the potential genetic markers CHI3L1, CD36, LEPR, RETN, IL-18, RBP-4, and RARRES2 genes.

Prognostic performance of serum YKL-40 for one-year clinical outcomes in acute ischemic stroke

BACKGROUND

Effects of YKL-40 on one-year clinical outcomes including poor clinical outcome, all-cause mortality, and stroke recurrence among acute ischemic stroke (AIS) patients remained elusive. The purpose of this study was to explore the association between serum YKL-40 at admission and one-year clinical outcomes in AIS patients.

METHODS

In this prospective cohort study, a total of 1002 participants out of 1361 AIS patients from two centers were included for current analysis. Serum YKL-40 concentrations were measured via enzyme-linked immunosorbent assay. Multivariable logistic or Cox regression were performed to explore the independent association of YKL-40 with one-year clinical outcomes, including poor outcome (modified Rankin Scale of 3-6), all-cause mortality, and recurrent stroke. C-statistic, net reclassification index (NRI) and integrated discrimination improvement (IDI) were calculated to evaluate the discriminatory and predictive power of YKL-40 when added to conventional model.

RESULTS

Compared with the first quartile of YKL-40, the adjusted odds ratios or hazard ratios with 95% confidence intervals of the fourth quartile were 3.032 (1.627-5.650) for poor outcome, 2.886 (1.320-6.308) for all-cause mortality and 1.694 (0.906-3.169) for recurrent stroke. The addition of serum YKL-40 to conventional model significantly improved reclassification for poor outcome (NRI 0.053, P = 0.031; IDI 0.018, P = 0.001) and all-cause mortality (NRI 0.162, P = 0.036).

CONCLUSIONS

Elevated serum YKL-40 at admission might be independently associated with one-year poor outcome and all-cause mortality but not stroke recurrence among Chinese AIS patients.

The chitinases as biomarkers in immune-mediate diseases

The role of chitinases has been focused as potential biomarkers in a wide number of inflammatory diseases, in monitoring active disease state, and predicting prognosis and response to therapies. The main chitinases, CHIT1 and YKL-40, are derived from 18 glycosyl hydrolases macrophage activation and play important roles in defense against chitin-containing pathogens and in food processing. Moreover, chitinases may have organ- as well as cell-specific effects in the context of infectious diseases and inflammatory disorders and able to induce tissue remodelling. The CHIT1 measurement is an easy, reproducible, reliable, and cost-effective affordable assay. The clinical use of CHIT1 for the screening of lysosomal storage disorders is quite practical, when proper cut-off values are determined for each laboratory. The potential of CHIT1 and chitinases has not been fully explored yet and future studies will produce many surprising discoveries in the immunology and allergology fields of research. However, since the presence of a null CHIT1 gene in a subpopulation would be responsible of false-negative values, the assay should be completed with the other markers such ACE and, if necessary, by genetic analysis when CHIT1 is unexpected low.

Myocardial interaction of apixaban after experimental acute volume overload

Objective

Acute volume overload (AVO) induces early ischemia-like changes in intramyocardial arteries. We investigated whether the Factor Xa (FXa) inhibitor apixaban interacts with the myocardium early after AVO.

Methods

Fifty-five syngeneic Fisher rats underwent surgical abdominal aortocaval fistula to induce AVO. Among them, 17 rats were treated with apixaban (10 mg/kg/day). The myocardial outcome was studied using histological analysis and by measuring atrial natriuretic peptide (ANP) and matrix metalloprotease 9 (MMP9) gene expression.

Results

After 3 days, the total number of intramyocardial arteries was significantly increased in the AVO+apixaban (AVO+A) group compared with that in the AVO group (12.0  ±  1.2 and 10.2 ± 1.5, point score units, respectively). In the AVO+A group, there were significantly more edematous nuclei in myocardial arteries in the right and left ventricle compared with that in the AVO group. ANP and MMP9 expression levels continued to increase significantly in the AVO+A group compared with those in the AVO group.

Conclusion

Apixaban interacts with intramyocardial arteries in the left and right ventricles after AVO and ANP and MMP9 expression levels increased. Thus, the myocardial effect of Factor Xa inhibition needs to be monitored after AVO.

Plasma Human Cartilage Glycoprotein‐39 Is Associated With the Prognosis of Acute Ischemic Stroke

Background

To evaluate the prognostic value of plasma YKL‐40 (human cartilage glycoprotein‐39) for acute ischemic stroke.

Methods and Results

We measured plasma YKL‐40 levels in 3377 participants from CATIS (China Antihypertensive Trial in Acute Ischemic Stroke). Study outcome data on death, major disability (modified Rankin Scale score ≥3), and vascular diseases were collected at 3 months after stroke onset. The primary outcome was defined as a combination of death and major disability. During the 3‐month follow‐up, 828 participants (24.5%) experienced major disability or died. After multivariate adjustment, the highest YKL‐40 quartile was associated with an increased risk of the primary outcome (odds ratio, 1.426 [95% CI, 1.105–1.839]; P trend =0.01) compared with the lowest quartile. Each SD increase in log‐transformed YKL‐40 level was associated with a 15.5% (95% CI, 5.6–26.3%) increased risk of the primary outcome. The multivariable‐adjusted spline regression models showed a linear dose–response relationship between YKL‐40 and clinical outcomes. Adding YKL‐40 to a model containing conventional risk factors significantly improved the reclassification power for the primary outcome (net reclassification improvement: 15.61%, P <0.001; integrated discrimination index: 0.37%, P =0.004) and marginally significantly improved the discriminatory power for the primary outcome (area under the receiver operating characteristic curve improved by 0.003, P =0.099).

Conclusions

A higher YKL‐40 level in the acute phase of ischemic stroke was associated with an increased risk of mortality and major disability at 3 months after stroke, indicating that YKL‐40 may play an important role as a prognostic marker of ischemic stroke.

Registration

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01840072.

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.

Role of Chitinase-3-like Protein 1 in Cardioprotection and Angiogenesis by Post-Infarction Exercise Training

Chitinase-3-like protein 1 (CHI3L1) is a myokine involving tissue remodeling and inflammatory processes. CHI3L1 and its receptor protease-activated receptor 2 (PAR2) are induced by exercise in skeletal muscles. However, it remains unknown if CHI3L1/PAR2 signaling also mediates exercise-induced cardioprotection after myocardial infarction. Twenty-four adult male rats were divided into three groups (n = 8/group), receiving: (1) a sham operation; (2) permanent ligation of left anterior descending coronary artery; and (3) post-MI exercise training with one-week adaptive treadmill exercise for seven days followed by four weeks of aerobic exercise. Left ventricular systolic and end-diastolic pressure indices were measured and cardiac fibrosis, and angiogenesis were examined. Furthermore, HUVEC cells were treated in vitro with AMPK agonist—AICAR (a putative pharmacological memetic of exercise), recombinant human CHI3L1, PAR2 receptor blocker (AZ3451), and PI3K inhibitor (LY294002), respectively. We found that post-MI exercise significantly upregulated CHI3L1, PAR2, pPI3K/PI3K, pAKT/AKT, pERK/ERK, improved cardiac function, and diminished fibrosis. AICAR increased HUVEC tubules formation and upregulated CHI3L1 and PAR2 and these changes were attenuated by PAR2 blocker. In conclusion, post-MI exercise training can effectively activate CHI3L1/PAR2 signaling, which led to the improved myocardial function and enhanced cardiac angiogenesis in the infarcted heart.

Th1, Th2 and Th17 inflammatory pathways predict cardiometabolic protein expression in serum of COVID-19 patients

A predominant source of complication in SARS-CoV-2 patients arises from a severe systemic inflammation that can lead to tissue damage and organ failure. The high inflammatory burden of this viral...

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.

Large-scale serum analysis identifies unique systemic biomarkers in psoriasis and hidradenitis suppurativa

BACKGROUND

Hidradenitis Suppurativa (HS) is now recognized as a systemic inflammatory disease, sharing molecular similarities with psoriasis. Direct comparison of the systemic inflammation in HS with psoriasis is lacking.

OBJECTIVES

To evaluate the serum proteome of HS and psoriasis, and to identify biomarkers associated with disease severity.

METHODS

In this cross-sectional study, 1,536 serum proteins were assessed using the Olink Explore (Proximity Extension Assay/PEA) high-throughput panel in moderate-to-severe HS (n=11), psoriasis (n=10) and age- and BMI-matched healthy controls (n=10).

RESULTS

HS displayed an overall greater dysregulation of circulating proteins, with 434 differentially expressed proteins (|FCH|≥1.2, p-value≤0.05) in HS versus controls, 138 in psoriasis versus controls, and 503 between HS and psoriasis. IL-17A levels and Th1/Th17 pathway enrichment were comparable between diseases, while HS presented greater TNF and IL-1β-related signaling. Th17-associated markers, PI3 and LCN2, were able to accurately differentiate psoriasis from HS. Both diseases presented increases of atherosclerosis-related proteins. Robust correlations between clinical severity scores and immune and atherosclerosis-related proteins were observed across both diseases.

CONCLUSIONS

HS and psoriasis share significant Th1/Th17 enrichment and upregulation of atherosclerosis-related proteins. Nevertheless, despite the greater body surface area involved in psoriasis, HS presents a greater serum inflammatory burden.

The associations between red cell distribution width and plasma proteins in a general population

Background

High red cell distribution width (RDW) has been increasingly recognized as a risk factor for cardiovascular diseases (CVDs), but the underlying mechanisms remain unknown. Our aim was to explore the associations between RDW and plasma proteins implicated in the pathogenesis of CVD using a targeted proteomics panel.

Methods

RDW and 88 plasma proteins were measured in a population-based cohort study (n = 4726), Malmö Diet and Cancer-Cardiovascular Cohort (MDC-CC). A random 2/3 of the cohort was used as discovery sample and remaining 1/3 was used for replication. Multiple linear regression was used to assess the associations between RDW and plasma proteins, with adjustments for age, sex, and other potential confounders. Proteins with Bonferroni-corrected significant associations with RDW in the discovery sub-cohort were validated in the replication cohort.

Results

Thirteen of 88 plasma proteins had significant associations with RDW in the discovery sample, after multivariate adjustments. Eleven of them were also significant in the replication sample, including SIR2-like protein 2 (SIRT2), stem cell factor (SCF, inversely), melusin (ITGB1BP2), growth differentiation factor-15 (GDF-15), matrix metalloproteinase-7 (MMP-7), hepatocyte growth factor (HGF), chitinase-3-like protein 1 (CHI3L1), interleukin-8 (IL-8), CD40 ligand (CD40-L), urokinase plasminogen activator surface receptor (U-PAR) and matrix metalloproteinase-3 (MMP-3).

Conclusions

Several proteins from this targeted proteomics panel were associated with RDW in this cohort. These proteins could potentially be linked to the increased cardiovascular risk in individuals with high RDW.

YKL-40 Is Associated With Ultrasound-Determined Carotid Atherosclerotic Plaque Instability

Background and Aims: YKL-40, an inflammatory biomarker, has been reported to be involved in the process and progression of atherosclerosis. Several studies have investigated the association between YKL-40 and plaque and suggested YKL-40 might be a potential biomarker for plaque instability. This study aimed to investigate the association between YKL-40 and carotid plaque instability.

Methods: Based on a community-based study in Beijing from February 2014 to May 2016, 1,132 participants with carotid plaques were enrolled in this study. Data on demographics and medical history were collected through face-to-face interviews, and fasting blood samples were collected and stored. We used ultrasound to evaluate the presence of carotid plaque and its instability. The level of YKL-40 was measured by enzyme-linked immunosorbent assay (ELISA). Multivariate logistic regression analysis was performed to investigate the association between YKL-40 level and carotid atherosclerotic plaque instability.

Results: The mean age of the 1,132 participants was 58.0 (52.0–64.0) years, and 560 (49.5%) were male. Unstable plaques were detected in 855 (75.53%) participants. YKL-40 level was classified into four groups according to its quartile: quartile 1: <25.47 ng/mL, quartile 2: 25.47–39.53 ng/mL, quartile 3: 39.53–70.55 ng/mL, quartile 4: ≥70.55 ng/mL. After adjusting for age, sex, smoking, alcohol drinking, medical history, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, homocysteine, high-sensitivity C-reactive protein, and plaque thickness, the top quartiles of YKL-40 level were significantly associated with unstable plaque (quartile 3: OR 2.10, 95% CI 1.29–3.40; quartile 4: OR 1.70, 95% CI 1.04–2.80).

Conclusion: This study found that YKL-40 was associated with carotid plaque instability determined by ultrasound. Individuals with high YKL-40 may have a higher risk of unstable carotid plaque.

Association of CHI3L1 gene variants with YKL-40 levels and hypertension incidence: A population-based nested case-control study in China

YKL‐40 was reported to be associated with the risk of hypertension. Whether the variants of CHI3L1 gene were associated with both YKL‐40 levels and hypertension needs to be further elucidated. In a 1:1 matched case‐control study of 507 pairs with available YKL‐40 levels and DNA samples nested in a prospective cohort of Chinese subjects, the 15 tag single nucleotide polymorphisms (SNPs) of CHI3L1 gene were genotyped. The levels of YKL‐40 among different genotypes of each SNP were compared after false discovery rate adjustment. Multivariable conditional logistic regression analyses were used to explore the association between the genotypes and the risk of hypertension. Subjects with the genetic variants for rs10399931, rs1538372, rs2071580, rs2297839 and rs4950928 had lower YKL‐40 levels. The genetic variant for rs10399805 was associated with higher YKL‐40 level. Subjects with the genotype of GA/AA of rs10399805 had a 1.34‐fold risk of hypertension compared with those with GG genotype in the total population (P = .05). Subjects with heterozygote/rare homozygote genotype of rs4950928 and rs2297839 both had a significantly lower risk of hypertension compared with those with major homozygote genotype among men. The ORs (95% CIs) were 0.46 (0.23‐0.89) and 0.49 (0.26‐0.91), respectively. The above three SNPs could significantly improve the accuracy of risk prediction for hypertension based on the conventional factors. The genotypes of rs10399805, rs4950928 and rs2297839 may hopefully become stable biomarkers for predicting the risk of hypertension.

Associations of plasma YKL-40 concentrations with heel ultrasound parameters and bone turnover markers in the general adult population

OBJECTIVE

YKL-40, also known as chitinase-3-like protein 1, is a new proinflammatory biomarker, that might play a role in tissue remodeling and bone resorption. Here we evaluated the associations of the YKL-40 plasma concentration with heel ultrasound parameters and bone turnover markers (BTMs) in adult men and women from the general population. We tested for a causal role of YKL-40 on bone metabolism using published single nucleotide polymorphisms (SNPs) with consequences for YKL-40 expression and function.

METHODS

Data were obtained from two population-based cohorts: the Study of Health in Pomerania (SHIP) and SHIP-Trend. Quantitative ultrasound (QUS) measurements at the heel were performed and bone turnover was assessed by measurement of intact amino-terminal propeptide of type I procollagen (PINP) and carboxy-terminal telopeptide of type I collagen (CTX). Associations between the YKL-40 plasma concentration and the QUS-based parameters, bone turnover marker (BTM) concentrations and 44 SNPs, including the lead SNP rs4950928, were evaluated in 382 subjects. Furthermore, we assessed the associations between the same SNPs and the QUS-based parameters (n = 5777) or the BTM concentrations (n = 7190).

RESULTS

Sex-specific linear regression models adjusted for a comprehensive panel of interfering covariantes revealed statistically significant inverse associations between YKL-40 and all QUS-based parameters as well as positive associations with CTX in women. The rs4950928 polymorphism was associated with YKL-40 in men and women but none of the tested SNPs was associated with the QUS-based parameters or the BTMs after correction for multiple testing.

CONCLUSIONS

Plasma YKL-40 concentrations are associated with QUS-based parameters as well as CTX concentrations in women but these associations are probably not causal.

Chitinase-3 like-protein-1 function and its role in diseases

Non-enzymatic chitinase-3 like-protein-1 (CHI3L1) belongs to glycoside hydrolase family 18. It binds to chitin, heparin, and hyaluronic acid, and is regulated by extracellular matrix changes, cytokines, growth factors, drugs, and stress. CHI3L1 is synthesized and secreted by a multitude of cells including macrophages, neutrophils, synoviocytes, chondrocytes, fibroblast-like cells, smooth muscle cells, and tumor cells. It plays a major role in tissue injury, inflammation, tissue repair, and remodeling responses. CHI3L1 has been strongly associated with diseases including asthma, arthritis, sepsis, diabetes, liver fibrosis, and coronary artery disease. Moreover, following its initial identification in the culture supernatant of the MG63 osteosarcoma cell line, CHI3L1 has been shown to be overexpressed in a wealth of both human cancers and animal tumor models. To date, interleukin-13 receptor subunit alpha-2, transmembrane protein 219, galectin-3, chemo-attractant receptor-homologous 2, and CD44 have been identified as CHI3L1 receptors. CHI3L1 signaling plays a critical role in cancer cell growth, proliferation, invasion, metastasis, angiogenesis, activation of tumor-associated macrophages, and Th2 polarization of CD4⁺ T cells. Interestingly, CHI3L1-based targeted therapy has been increasingly applied to the treatment of tumors including glioma and colon cancer as well as rheumatoid arthritis. This review summarizes the potential roles and mechanisms of CHI3L1 in oncogenesis and disease pathogenesis, then posits investigational strategies for targeted therapies.

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.

Roles of chitinase 3-like 1 in the development of cancer, neurodegenerative diseases, and inflammatory diseases

Chitinase 3-like 1 (CHI3L1) is a secreted glycoprotein that mediates inflammation, macrophage polarization, apoptosis, and carcinogenesis. The expression of CHI3L1 is strongly increased by various inflammatory and immunological conditions, including rheumatoid arthritis, multiple sclerosis, Alzheimer's disease, and several cancers. However, its physiological and pathophysiological roles in the development of cancer and neurodegenerative and inflammatory diseases remain unclear. Several studies have reported that CHI3L1 promotes cancer proliferation, inflammatory cytokine production, and microglial activation, and that multiple receptors, such as advanced glycation end product, syndecan-1/αVβ3, and IL-13Rα2, are involved. In addition, the pro-inflammatory action of CHI3L1 may be mediated via the protein kinase B and phosphoinositide-3 signaling pathways and responses to various pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and interferon-γ. Therefore, CHI3L1 could contribute to a vast array of inflammatory diseases. In this article, we review recent findings regarding the roles of CHI3L1 and suggest therapeutic approaches targeting CHI3L1 in the development of cancers, neurodegenerative diseases, and inflammatory diseases.

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.

Cadherin-11 as a regulator of valve myofibroblast mechanobiology

Cadherin-11 (CDH11) is upregulated in a variety of fibrotic diseases, including arthritis and calcific aortic valve disease. Our recent work has identified CDH11 as a potential therapeutic target and shown that treatment with a CDH11 functional blocking antibody can prevent hallmarks of calcific aortic valve disease in mice. The present study investigated the role of CDH11 in regulating the mechanobiological behavior of valvular interstitial cells believed to cause calcification. Aortic valve interstitial cells were harvested from Cdh11^+/+, Cdh11^+/-, and Cdh11^-/- immortomice. Cells were subjected to inflammatory cytokines transforming growth factor (TGF)-β₁ and IL-6 to characterize the molecular mechanisms by which CDH11 regulates their mechanobiological changes. Histology was performed on aortic valves from Cdh11^+/+, Cdh11^+/-, and Cdh11^-/- mice to identify key responses to CDH11 deletion in vivo. We showed that CDH11 influences cell behavior through its regulation of contractility and its ability to bind substrates via focal adhesions. We also show that transforming growth factor-β₁ overrides the normal relationship between CDH11 and smooth muscle α-actin to exacerbate the myofibroblast disease phenotype. This phenotypic switch is potentiated through the IL-6 signaling axis and could act as a paracrine mechanism of myofibroblast activation in neighboring aortic valve interstitial cells in a positive feedback loop. These data suggest CDH11 is an important mediator of the myofibroblast phenotype and identify several mechanisms by which it modulates cell behavior. NEW & NOTEWORTHY Cadherin-11 influences valvular interstitial cell contractility by regulating focal adhesions and inflammatory cytokine secretion. Transforming growth factor-β₁ overrides the normal balance between cadherin-11 and smooth muscle α-actin expression to promote a myofibroblast phenotype. Cadherin-11 is necessary for IL-6 and chitinase-3-like protein 1 secretion, and IL-6 promotes contractility. Targeting cadherin-11 could therapeutically influence valvular interstitial cell phenotypes in a multifaceted manner.

Atherosclerosis is exacerbated by chitinase-3-like-1 in amyloid precursor protein transgenic mice

Although the important role of amyloid precursor protein (APP) in vascular diseases associated with Alzheimer's disease (AD) has been demonstrated, the underlying molecular mechanisms and physiological consequences are unclear. We aimed to evaluate vascular inflammation and atherosclerosis in Swedish mutant of human APP transgenic (APPsw-Tg) and ApoE^-/-/APPsw-Tg mice. We also aimed to explore the mechanisms underlying any changes observed in these mice compared with non-Tg controls. Methods: The transgenic and non-Tg mouse strains were subjected to partial ligation of the left carotid artery to induce atherosclerotic changes, which were measured using histological approaches, immunohistochemistry, quantitative polymerase chain reaction, and gene expression microarrays. Results: Our results showed increased vascular inflammation, arterial wall thickness, and atherosclerosis in APPsw-Tg and ApoE^-/-/APPsw-Tg mice. We further found that the expression of chitinase-3-like-1 (Chi3l1) is increased in the APPsw-Tg mouse artery and Chi3l1 mediates endothelial cell (EC) inflammation and vascular smooth muscle cell (VSMC) activation, which in turn exacerbates atherosclerosis. In addition, using two publicly available microarray datasets from the dorsolateral prefrontal cortex of people with AD and unaffected controls as well as inflamed human umbilical vein endothelial cells, we found that Chi3l1 and associated inflammatory gene were significantly associated with AD, evaluated by co-expression network analysis and functional annotation. Knockdown of Chi3l1 in the arterial endothelium in vivo suppressed the development of atherosclerosis. We also show that microRNA 342-3p (miR-342-3p) inhibits EC inflammation and VSMC activation through directly targeting Chi3l1, and that APPsw increased Chi3l1 expression by reducing miR-342-3p expression in the arterial endothelium, promoting atherosclerosis. Conclusion: Our findings suggest that targeting Chi3l1 might provide new diagnostic and therapeutic strategies for vascular diseases in patients with AD.

Deciphering the Relationship between Obesity and Various Diseases from a Network Perspective

The number of obesity cases is rapidly increasing in developed and developing countries, thereby causing significant health problems worldwide. The pathologic factors of obesity at the molecular level are not fully characterized, although the imbalance between energy intake and consumption is widely recognized as the main reason for fat accumulation. Previous studies reported that obesity can be caused by the dysfunction of genes associated with other diseases, such as myocardial infarction, hence providing new insights into dissecting the pathogenesis of obesity by investigating its associations with other diseases. In this study, we investigated the relationship between obesity and diseases from Online Mendelian Inheritance in Man (OMIM) databases on the protein–protein interaction (PPI) network. The obesity genes and genes of one OMIM disease were mapped onto the network, and the interaction scores between the two gene sets were investigated on the basis of the PPI of individual gene pairs, thereby inferring the relationship between obesity and this disease. Results suggested that diseases related to nutrition and endocrine are the top two diseases that are closely associated with obesity. This finding is consistent with our general knowledge and indicates the reliability of our obtained results. Moreover, we inferred that diseases related to psychiatric factors and bone may also be highly related to obesity because the two diseases followed the diseases related to nutrition and endocrine according to our results. Numerous obesity–disease associations were identified in the literature to confirm the relationships between obesity and the aforementioned four diseases. These new results may help understand the underlying molecular mechanisms of obesity–disease co-occurrence and provide useful insights for disease prevention and intervention.

CHI3L1 is correlated with childhood asthma

OBJECTIVE

The aim of this study was to assess the association between CHI3L1 gene two single nucleotide polymorphisms (SNPs) (rs12141494 and rs4950928) and susceptibility to pediatric asthma in a Chinese Han population.

METHODS

The case-control study was carried out on 115 children with asthma and 108 healthy controls. Genotypes of rs12141494 and rs4950928 within CHI3L1 gene were determined with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach. Chi-square test was employed to analyze the differences of genotype and allele frequencies of the two polymorphisms between case and control groups. Odds ratios (ORs) and 95% confidence intervals (CIs) were applied to explain relative susceptibility of pediatric asthma.

RESULTS

The frequencies of genotypes and alleles of rs4950928 in CHI3L1 gene showed a significant difference between asthmatic children and healthy controls (P<0.05). However, no significant differences were found in CHI3L1 SNP rs12141494 between two groups (P>0.05).

CONCLUSION

Our results suggested that rs4950928 in CHI3L1 gene was associated with pediatric asthma risk in a Chinese Han population, while rs12141494 was not.

YKL-40 is a novel biomarker for predicting hypertension incidence among prehypertensive subjects: A population-based nested case-control study in China

BACKGROUND AND AIMS

The previous study suggested that Human cartilage glycoprotein-39 (YKL-40) was positively associated with hypertension incidence in certain high-risk groups of hypertension. We aimed to investigate that whether YKL-40 is an effective biomarker for predicting hypertension incidence among prehypertensive subjects.

METHODS

In a 1:1 matched case-control study of 700 pairs with available YKL-40 levels nested in a prospective cohort of initially healthy Chinese subjects, 294 pairs additionally have matched baseline BP status (prehypertensive or normotensive). Multivariable conditional logistic regression analyses were used to calculate the odds ratios (95% confidential intervals) of hypertension associated with higher levels of YKL-40 in both prehypertensive and normotensive subgroups, respectively.

RESULTS

In the prehypertensive subgroup, the subjects in the highest quartile of plasma YKL-40 levels had a significantly higher risk of hypertension incidence, compared with those in the lowest quartile. The odds ratio (95% confidential intervals) is 2.01 (1.05-3.85). A positive association between YKL-40 levels and hypertension incidence was found (P for trend<0.05). However, this significant association was not observed in the normotensive subgroup.

CONCLUSIONS

Higher YKL-40 levels at baseline were positively associated with hypertension incidence among prehypertensive subjects. YKL-40 may represent a novel biomarker for predicting hypertension risk in prehypertension population.

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.

YKL-40 Level and Hypertension Incidence: A Population-Based Nested Case-Control Study in China

Background

Human cartilage glycoprotein‐39 (YKL‐40) has been suggested to be a new marker of inflammation, atherosclerosis, and endothelial dysfunction. However, whether a higher level of YKL‐40 is an independent risk factor for hypertension incidence is still unknown.

Methods and Results

In a nested case‐control study within a prospective cohort of 12 423 initially healthy Chinese adults, we measured baseline plasma concentrations of YKL‐40 among 700 new‐onset hypertension cases and 700 age‐ and sex‐matched controls. Multiple conditional logistic regression analyses were used to calculate the odds ratios (95% CIs) of hypertension associated with higher levels of YKL‐40 both in the total population and in the age‐ (>55 and ≤55 years) and sex‐matched subgroups. Among the total population, YKL‐40 levels were not associated with hypertension risk. In the subgroup older than 55 years, odds ratios (95% CIs) of hypertension for those in the two higher tertiles of YKL‐40 were 1.23 (0.77–1.97) and 1.59 (0.99–2.55) (P for linear trend=0.05). In the male subgroup, odds ratios (95% CIs) of hypertension for those in the two higher tertiles of YKL‐40 were 1.55 (0.88–2.72) and 2.09 (1.14–3.82) (P for linear trend=0.02). An interaction effect was observed between YKL‐40 and sex (P for interaction <0.01) but not between YKL‐40 and age (P for interaction=0.21). High YKL‐40 level significantly increased hypertension risk in men but decreased hypertension risk with a trend although not significant in women.

Conclusions

This study suggests that YKL‐40 is associated with hypertension incidence only among men. The study findings need to be further verified by prospective cohort studies or clinical trials.

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.

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.

Observationally and Genetically High YKL-40 and Risk of Venous Thromboembolism in the General Population: Cohort and Mendelian Randomization Studies

OBJECTIVE

High baseline YKL-40 is associated with later development of ischemic stroke, but not with myocardial infarction. Whether high YKL-40 levels are associated with increased risk of venous thromboembolism is presently unknown. We tested the hypothesis that observationally and genetically high YKL-40 is associated with increased risk of venous thromboembolism in the general population.

APPROACH AND RESULTS

Cohort and Mendelian randomization studies in 96 110 individuals from the Danish general population, with measured plasma levels of YKL-40 (N=21 647) and CHI3L1 rs4950928 genotype (N=94 579). From 1977 to 2013, 1489 individuals developed pulmonary embolism, 2647 developed deep vein thrombosis, and 3750 developed venous thromboembolism (pulmonary embolism and deep vein thrombosis). For the 91% to 100% versus 0% to 33% YKL-40 percentile category, the multifactorially adjusted hazard ratio was 2.38 (95% confidence interval, 1.25-4.55) for pulmonary embolism, 1.98 (1.09-3.59) for deep vein thrombosis, and 2.13 (1.35-3.35) for venous thromboembolism. Compared with rs4950928 GG homozygosity, presence of C-allele was associated with a doubling (CG) or tripling (CC) in YKL-40 levels, but not with risk of venous thromboembolism. A doubling in YKL-40 was associated with a multifactorially adjusted observational hazard ratio for pulmonary embolism of 1.17 (1.00-1.38) and a genetic odds ratio of 0.97 (0.76-1.23). Corresponding risk estimates were 1.28 (1.12-1.47) observationally and 1.11 (0.91-1.35) genetically for deep vein thrombosis and 1.23 (1.10-1.38) observationally and 1.08 (0.92-1.27) genetically for venous thromboembolism.

CONCLUSIONS

High YKL-40 levels were associated with a 2-fold increased risk of venous thromboembolism, but the association was not causal.

Asthma Associates With Human Abdominal Aortic Aneurysm and Rupture

OBJECTIVE

Both asthma and abdominal aortic aneurysms (AAA) involve inflammation. It remains unknown whether these diseases interact.

APPROACH AND RESULTS

Databases analyzed included Danish National Registry of Patients, a population-based nationwide case-control study included all patients with ruptured AAA and age- and sex-matched AAA controls without rupture in Denmark from 1996 to 2012; Viborg vascular trial, subgroup study of participants from the population-based randomized Viborg vascular screening trial. Patients with asthma were categorized by hospital diagnosis, bronchodilator use, and the recorded use of other anti-asthma prescription medications. Logistic regression models were fitted to determine whether asthma associated with the risk of ruptured AAA in Danish National Registry of Patients and an independent risk of having an AAA at screening in the Viborg vascular trial. From the Danish National Registry of Patients study, asthma diagnosed <1 year or 6 months before the index date increased the risk of AAA rupture before (odds ratio [OR]=1.60-2.12) and after (OR=1.51-2.06) adjusting for AAA comorbidities. Use of bronchodilators elevated the risk of AAA rupture from ever use to within 90 days from the index date, before (OR=1.10-1.37) and after (OR=1.10-1.31) adjustment. Patients prescribed anti-asthma drugs also showed an increased risk of rupture before (OR=1.12-1.79) and after (OR=1.09-1.48) the same adjustment. In Viborg vascular trial, anti-asthmatic medication use associated with increased risk of AAA before (OR=1.45) or after adjustment for smoking (OR=1.45) or other risk factors (OR=1.46).

CONCLUSIONS

Recent active asthma increased risk of AAA and ruptured AAA. These findings document and furnish novel links between airway disease and AAA, 2 common diseases that share inflammatory aspects.

The Role of CHI3L1 (Chitinase-3-Like-1) in the Pathogenesis of Infections in Burns in a Mouse Model

In severe burn injury the unique setting of a depleted, dysfunctional immune system along with a loss of barrier function commonly results in opportunistic infections that eventually proof fatal. Unfortunately, the dynamic sequence of bacterial contamination, colonization and eventually septic invasion with bacteria such as Pseudomonas species is still poorly understood although a limiting factor in clinical decision making. Increasing evidence supports the notion that inhibition of bacterial translocation into the wound site may be an effective alternative to prevent infection. In this context we investigated the role of the mammalian Chitinase-3-Like-1 (CHI3L1) non-enyzmatic protein predominately expressed on epithelial as well as innate immune cells as a potential bacterial-translocation-mediating factor. We show a strong trend that a modulation of chitinase expression is likely to be effective in reducing mortality rates in a mouse model of burn injury with superinfection with the opportunistic PA14 Pseudomonas strain, thus demonstrating possible clinical leverage.

New inflammatory markers for prediction of non-dipper blood pressure pattern in patients with essential hypertension: Serum YKL-40/Chitinase 3-like protein 1 levels and echocardiographic epicardial adipose tissue thickness

The aim of the present study was to investigate whether YKL-40 levels and epicardial adipose tissue (EAT) thickness were associated with non-dipping pattern in essential hypertension (HT). Age- and sex-matched 40 dipper hypertensive patients and 40 non-dipper hypertensive patients were included in the study. Non-dippers had significantly increased EAT thickness and higher YKL-40 and high-sensitivity C-reactive protein levels than dippers. Multivariate logistic regression analysis showed that the EAT thickness and serum levels of YKL-40 and high-sensitivity C-reactive protein were independent predictors of non-dipping pattern in essential HT. In essential HT, presence of non-dipping pattern is associated with increased inflammatory response.

Elevated Plasma YKL-40, Lipids and Lipoproteins, and Ischemic Vascular Disease in the General Population

Background and Purpose—

We tested the hypothesis that observationally and genetically elevated YKL-40 is associated with elevated lipids and lipoproteins and with increased risk of ischemic vascular disease.

Methods—

We conducted cohort and Mendelian randomization studies in 96 110 individuals from the Danish general population, with measured plasma levels of YKL-40 (n=21 647), plasma lipids and lipoproteins (n=94 461), and CHI3L1 rs4950928 genotype (n=94 579).

Results—

From 1977 to 2013, 3256 individuals developed ischemic stroke, 5629 ischemic cerebrovascular disease, 4183 myocardial infarction, and 10 271 developed ischemic heart disease. The 91% to 100% versus 0% to 33% YKL-40 percentile category was associated with a 34% increase in triglycerides, but only with minor changes in other lipids and lipoproteins. For these categories, the multifactorially adjusted hazard ratio was 1.99 (95% confidence interval, 1.49–2.67) for ischemic stroke, 1.85 (1.44–2.37) for ischemic cerebrovascular disease, 1.28 (0.95–1.73) for myocardial infarction, and 1.23 (1.01–1.51) for ischemic heart disease. When compared with rs4950928 GG homozygosity, the presence of C-allele was associated with a doubling (CG) or tripling (CC) in YKL-40 levels, but not with triglyceride levels or with risk of ischemic vascular disease. A doubling in YKL-40 was associated with a multifactorially adjusted observational hazard ratio for ischemic stroke of 1.18 (1.11–1.27), and a genetic odds ratio of 1.04 (0.95–1.15). Corresponding risk estimates were 1.15 (1.09–1.22) observationally and 1.06 (0.99–1.14) genetically for ischemic cerebrovascular disease, 1.08 (1.00–1.15) observationally and 1.04 (0.96–1.13) genetically for myocardial infarction, and 1.07 (1.02–1.12) observationally and 1.01 (0.96–1.07) genetically for ischemic heart disease.

Conclusions—

Elevated YKL-40 was associated with a 34% increase in triglyceride levels and with a 2-fold increased risk of ischemic stroke, whereas genetically elevated YKL-40 were not.

miR-24 limits aortic vascular inflammation and murine abdominal aneurysm development

Identification and treatment of abdominal aortic aneurysm (AAA) remain among the most prominent challenges in vascular medicine. MicroRNAs (miRNAs) are crucial regulators of cardiovascular pathology and represent intriguing targets to limit AAA expansion. Here we show, by using two established murine models of AAA disease along with human aortic tissue and plasma analysis, that miR-24 is a key regulator of vascular inflammation and AAA pathology. In vivo and in vitro studies reveal chitinase 3-like 1 (Chi3l1) to be a major target and effector under the control of miR-24, regulating cytokine synthesis in macrophages as well as their survival, promoting aortic smooth muscle cell migration and cytokine production, and stimulating adhesion molecule expression in vascular endothelial cells. We further show that modulation of miR-24 alters AAA progression in animal models, and that miR-24 and CHI3L1 represent novel plasma biomarkers of AAA disease progression in humans.

Abdominal aortic aneurysm (AAA) is a potentially fatal and often asymptomatic disease whose causes remain unclear. Here the authors show that a microRNA, miR-24, and its target, the glycoprotein chitinase 3-like 1, represent key regulators of AAA development.