Elevated plasma YKL-40 and risk of infectious disease: a prospective study of 94665 individuals from the general population

Human chitinases and chitinase-like proteins as emerging drug targets - a medicinal chemistry perspective

Human chitinases and chitinase-like proteins (CLPs) provide the immune system with the ability to recognize or process chitin originating from chitinous pathogens. In addition to their role in host defense, most members of this protein family have evolved pleiotropic cellular effector functions broadly related to immune homeostasis, cell proliferation, and tissue remodeling. This wide-ranging ability to modulate crucial cellular processes proceeds via the activation of cellular signal transduction cascades and appears to be fully independent of chitin recognition. Dysregulation of chitinase/CLP functions has been linked to a plethora of inflammatory diseases, such as allergic airway diseases and asthma, fibrosis, as well as cancer. This fact predetermines certain members of this protein family as prime targets for pharmacological intervention. Here, we provide an extensive review of medicinal chemistry efforts targeting the most widely studied members of the human chitinase/CLP family, namely acidic mammalian chitinase (AMCase), chitotriosidase (CHIT1), and chitinase-3-like protein 1 (CHI3L1/YKL-40).

Omics data integration analysis identified new biological insights into chronic antibody-mediated rejection (CAMR)

BACKGROUND

In the last two decades, many studies based on omics technologies have contributed to defining the clinical, immunological, and histological fingerprints of chronic antibody-mediated rejection (CAMR), the leading cause of long-term kidney allograft failure. However, the full biological machinery underlying CAMR has only been partially defined, likely due to the fact thatsingle-omics technologies capture only specific aspects of the biological system and fail to provide a comprehensive understanding of this clinical complication.

METHODS

This study integrated mass spectrometry-based proteomic profiling of serum samples from 19 patients with clinical and histological evidence of CAMR and 26 kidney transplant recipients with normal graft function and histology (CTR) with transcriptomic analysis of peripheral blood mononuclear cells (PBMCs) from an independent cohort of 10 CAMR and 8 CTR patients. Data analysis was conducted using unsupervised hierarchical clustering (multidimensional scaling with k-means) and Spearman's correlation test. Partial least squares discriminant analysis (PLS-DA) with the importance in projection (VIP) score identified key proteins differentiating CAMR from CTR. ELISA was used to validate the omics results.

RESULTS

Proteomic analysis identified 18 proteins that significantly differentiated CAMR from CTR (p < 0.01): five were more abundant (CHI3L1, LYZ, PRSS2, CPQ, IGLV3-32), while 13 were less abundant (SERPINA5, SERPING1, KNG1, CAMP, VNN1, BTD, WDR1, PON3, AHNAK2, MELTF, CA1, CD44, CUL1). Transcriptomic profiling revealed 6 downregulated and 33 upregulated genes in CAMR versus CTR (p < 0.01). Notably, only 2 biological elements were significantly deregulated in both omics analyses: chitinase-3-like protein 1 (CHI3L1) and plasma protease inhibitor C1 (SERPING1). CHI3L1, previously associated with the severity of tissue damage in kidney diseases, was up-regulated in CAMR in both transcriptomics and proteomics, while SERPING1, a serine esterase inhibitor that blocks the classical and lectin pathway of complement, was up-regulated in CAMR in transcriptomics but down-regulated in proteomics. ELISA validated the omics results, and the ROC curve showed that CHI3L1 has good discrimination power between CAMR and CTR (AUC of ROC curve of 0.81).

CONCLUSIONS

Our multi-omics data, although performed in a relatively small cohort of patients, revealed new systemic biological elements involved in the pathogenesis of CAMR and identified CHI3L1 as a new potential biomarker and/or therapeutic target for this important clinical complication. Future validation of these findings in larger patient cohorts should be conducted to better evaluate their clinical utility.

Location-based prediction model for Crohn's disease regarding a novel serological marker, anti-chitinase 3-like 1 autoantibodies

BACKGROUND

Defective neutrophil regulation in inflammatory bowel disease (IBD) is thought to play an important role in the onset or manifestation of IBD, as it could lead to damage of the intestinal mucosal barrier by the infiltration of neutrophils in the inflamed mucosa and the accumulation of pathogens. Like neutrophils in the context of innate immune responses, immunoglobulin A (IgA) as an acquired immune response partakes in the defense of the intestinal epithelium. Under normal conditions, IgA contributes to the elimination of microbes, but in connection with the loss of tolerance to chitinase 3-like 1 (CHI3L1) in IBD, IgA could participate in CHI3L1-mediated improved adhesion and invasion of potentially pathogenic microorganisms. The tolerance brake to CHI3L1 and the occurrence of IgA autoantibodies to this particular target, the exact role and underlying mechanisms of CHI3L1 in the pathogenesis of IBD are still unclear.

AIM

To determine the predictive potential of Ig subtypes of a novel serological marker, anti-CHI3L1 autoantibodies (aCHI3L1) in determining the disease phenotype, therapeutic strategy and long-term disease course in a prospective referral cohort of adult IBD patients.

METHODS

Sera of 257 Crohn's disease (CD) and 180 ulcerative colitis (UC) patients from a tertiary IBD referral center of Hungary (Division of Gastroenterology, Department of Internal Medicine, Faculty of Medicine, University of Debrecen) were assayed for IgG, IgA, and secretory IgA (sIgA) type aCHI3L1 by enzyme-linked immunosorbent assay using recombinant CHI3L1, along with 86 healthy controls (HCONT).

RESULTS

The IgA type was more prevalent in CD than in UC (29.2% vs 11.1%) or HCONT (2.83%; P < 0.0001 for both). However, sIgA subtype aCHI3L1 positivity was higher in both CD and UC patients than in HCONT (39.3% and 32.8% vs 4.65%, respectively; P < 0.0001). The presence of both IgA and sIgA aCHI3L1 antibodies was associated with colonic involvement (P < 0.0001 and P = 0.038, respectively) in patients with CD. Complicated disease behavior at sample procurement was associated with aCHI3L1 sIgA positivity (57.1% vs 36.0%, P = 0.009). IgA type aCH3L1 was more prevalent in patients with frequent relapse during the disease course in the CD group (46.9% vs 25.7%, P = 0.005). In a group of patients with concomitant presence of pure inflammatory luminal disease and colon involvement at the time of diagnosis, positivity for IgA or sIgA type aCH3L1 predicted faster progression towards a complicated disease course in time-dependent models. This association disappeared after merging subgroups of different disease locations.

CONCLUSION

CHI3L1 is a novel neutrophil autoantigenic target in IBD. The consideration of antibody classes along with location-based prediction may transform the future of serology in IBD.

Serum YKL-40 as a Potential Biomarker for Sepsis in Term Neonates-A Pilot Study

Although YKL-40 is a promising diagnostic biomarker of sepsis in adults, its value in neonatal sepsis is not known. The study objectives included assessing the levels and diagnostic value of serum YKL-40 in term neonates with sepsis and comparing YKL-40 with other commonly used inflammatory biomarkers. In this pilot case-control study, 45 term neonates (30 septic and 15 non-septic, as controls), 4 to 28 days old, were prospectively studied. The International Pediatric Sepsis Consensus Conference criteria were applied to diagnose sepsis. During the acute phase (admission) and remission of sepsis, blood samples were collected from cases (while from controls they were only collected once) for routine laboratory tests, cultures, and the measurement of serum YKL-40 levels via Elisa. In the acute phase of sepsis, YKL-40 levels were significantly elevated in comparison with remission (p = 0.004) and controls (p = 0.003). YKL-40 levels did not differ significantly between patients in remission and controls (p = 0.431). Upon admission, YKL-40 levels correlated positively with white blood count, absolute neutrophil count, and CRP levels. Via ROC analysis, it was shown that YKL-40 levels upon admission were a significant indicator of sepsis (AUC = 0.771; 95% CI 0.632-0.911; p = 0.003). Serum YKL-40 might be considered as an adjuvant biomarker of sepsis in term neonates.

Independent Predictive Value of Elevated YKL-40 in Ischemic Stroke Prognosis: Findings from a Nationwide Stroke Registry

INTRODUCTION

Elevated circulatory concentrations of YKL-40 have been reported in patients with ischemic stroke. This study further investigated the association of plasma YKL-40 concentrations at admission and short, long-term prognosis after ischemic stroke.

METHODS

Based on a prospective, nationwide multicenter registry focusing consecutive patients of ischemic stroke and transient ischemic attack, plasma YKL-40 levels were detected by enzyme-linked immunosorbent assay at admission, and patients were stratified into percentile according to the plasma YKL-40 concentrations. The multivariate Cox or logistic regression model was used to investigate the association of YKL-40 concentration with death and functional outcomes at 3 months, 6 months, and 12 months after ischemic stroke, with potential confounders adjusted.

RESULTS

A total of 8,006 first-ever ischemic stroke patients, with the age of 61.7 ± 11.5, were included in this study. The mortality of 0-33%, 34-66%, 67-90%, and 91-100% groups at 12 months follow-up was 0.9%, 2.2%, 4.4%, and 9.4%, respectively (p < 0.0001), and the modified Rankin Scale 3-6 ratio was 6.8%, 10.5%, 15.7%, and 24.0%, respectively (p < 0.0001). In the multivariate regression, after adjusting for potential confounders, 91-100% group had higher risk of death (hazard ratio 2.99, 95% confidence interval 1.75-5.11)and modified Rankin Scale 3-6 (odds ratio 1.42, 95% confidence interval 1.08-1.88) at 12 months since onset of ischemic stroke compared to the 0-33% group.

CONCLUSIONS

The elevated YKL-40 at admission can potentially help predict death, functional prognosis after ischemic stroke, which may help further studies to explore the potential physiological and pathological mechanism including the effects of vulnerable plaque and collateral circulation.

Associations between YKL-40 and markers of disease severity and death in patients with necrotizing soft-tissue infection

Background

Necrotizing soft-tissue infection (NSTI) is a severe and fast-progressing bacterial infection. Prognostic biomarkers may provide valuable information in treatment guidance and decision-making, but none have provided sufficient robustness to have a clinical impact. YKL-40 may reflect the ongoing pathological inflammatory processes more accurately than traditional biomarkers as it is secreted by the activated immune cells, but its prognostic yields in NSTI remains unknown. For this purpose, we investigated the association between plasma YKL-40 and 30-day mortality in patients with NSTI, and assessed its value as a marker of disease severity.

Methods

We determined plasma YKL-40 levels in patients with NSTI (n = 161) and age-sex matched controls (n = 65) upon admission and at day 1, 2 and 3.

Results

Baseline plasma YKL-40 was 1191 ng/mL in patients with NSTI compared with 40 ng/mL in controls (p < 0.001). YKL-40 was found to be significantly higher in patients with septic shock (1942 vs. 720 ng/mL, p < 0.001), and in patients receiving renal-replacement therapy (2382 vs. 1041 ng/mL, p < 0.001). YKL-40 correlated with Simplified Acute Physiology Score II (Rho 0.33, p < 0.001). Baseline YKL-40 above 1840 ng/mL was associated with increased risk of 30-day mortality in age-sex-comorbidity adjusted analysis (OR 3.77, 95% CI; 1.59–9.24, p = 0.003), but after further adjustment for Simplified Acute Physiology Score II no association was found between YKL-40 and early mortality.

Conclusion

High plasma YKL-40 to be associated with disease severity, renal-replacement therapy and risk of death in patients with NSTI. However, YKL-40 is not an independent predictor of 30-day mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06760-x.

The Relationship Between Serum YKL-40 Levels on Admission and Stroke-Associated Pneumonia in Patients with Acute Ischemic Stroke

Background

Stroke-associated pneumonia (SAP) is a standout complication after acute ischemic stroke (AIS), with a prevalence of 7–38%. The aim of this prospective study was to investigate the relationship between serum YKL-40 levels at admission and SAP.

Methods

Between August 2020 and February 2021, consecutive AIS patients from two centers were enrolled prospectively. Serum YKL-40 concentrations were measured via enzyme-linked immunosorbent assay. We performed logistic regression analyses to explore the relationship between YKL-40 and SAP. Receiver operating characteristic curve was also used to assess the predictive ability of YKL-40 in predicting SAP.

Results

Ultimately, a total of 511 AIS patients were recruited. Multivariate logistic regression analysis showed that YKL-40 was independently related to SAP, whether as a continuous variable or as quartiles (P=0.001). The area under curve of YKL-40 to predict SAP was 0.765. The optimal cutoff value of YKL-40 as a predictor of SAP was determined to be 206.4 ng/mL, where the sensitivity was 63.1% and the specificity was 82.0%.

Conclusion

Our study demonstrated that YKL-40 might be considered as a useful biomarker to predict SAP in AIS patients.

Proteomic characteristics of bronchoalveolar lavage fluid in critical COVID-19 patients

Up to 10-20% of patients with coronavirus disease 2019 (COVID-19) develop a severe pulmonary disease due to immune dysfunction and cytokine dysregulation. However, the extracellular proteomic characteristics in respiratory tract of these critical COVID-19 patients still remain to be investigated. In the present study, we performed a quantitative proteomic analysis of the bronchoalveolar lavage fluid (BALF) from patients with critical COVID-19 and from non-COVID-19 controls. Our study identified 358 differentially expressed BALF proteins (P < 0.05), among which 41 were significantly changed after using the Benjamini-Hochberg correction (q < 0.05). The up-regulated signaling was found to be mainly involved in inflammatory signaling and response to oxidative stress. A series of increased extracellular factors including Tenascin-C (TNC), Mucin-1 (KL-6 or MUC1), Lipocalin-2 (LCN2), periostin (POSTN), Chitinase 3-like 1 (CHI3L1 or YKL40), and S100A12, and the antigens including lymphocyte antigen 6D/E48 antigen (LY6D), CD9 antigen, CD177 antigen, and prostate stem cell antigen (PSCA) were identified, among which the proinflammatory factors TNC and KL-6 were further validated in serum of another thirty-nine COVID-19 patients and healthy controls, showing high potentials of being biomarkers or therapeutic candidates for COVID-19. This BALF proteome associated with COVID-19 would also be a valuable resource for researches on anti-inflammatory medication and understanding the molecular mechanisms of host response. DATABASE: Proteomic raw data are available in ProteomeXchange (http://proteomecentral.proteomexchange.org) under the accession number PXD022085, and in iProX (www.iprox.org) under the accession number IPX0002429000.

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.

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.