Serum YKL-40 as a marker of disease activity and stricture formation in patients with Crohn's disease

Recently Updated Role of Chitinase 3-like 1 on Various Cell Types as a Major Influencer of Chronic Inflammation

Chitinase 3-like 1 (also known as CHI3L1 or YKL-40) is a mammalian chitinase that has no enzymatic activity, but has the ability to bind to chitin, the polymer of N-acetylglucosamine (GlcNAc). Chitin is a component of fungi, crustaceans, arthropods including insects and mites, and parasites, but it is completely absent from mammals, including humans and mice. In general, chitin-containing organisms produce mammalian chitinases, such as CHI3L1, to protect the body from exogenous pathogens as well as hostile environments, and it was thought that it had a similar effect in mammals. However, recent studies have revealed that CHI3L1 plays a pathophysiological role by inducing anti-apoptotic activity in epithelial cells and macrophages. Under chronic inflammatory conditions such as inflammatory bowel disease and chronic obstructive pulmonary disease, many groups already confirmed that the expression of CHI3L1 is significantly induced on the apical side of epithelial cells, and activates many downstream pathways involved in inflammation and carcinogenesis. In this review article, we summarize the expression of CHI3L1 under chronic inflammatory conditions in various disorders and discuss the potential roles of CHI3L1 in those disorders on various cell types.

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.

Increased visinin-like protein-1, YKL-40, lipocalin-2, and IL-23 levels in patients with migraine

BACKGROUND

Migraine is a type of primary headache caused by changes in the trigeminal system and has been reported to be associated with neurovascular inflammation of cerebral and extracerebral vessels.

OBJECTIVE

It is known that inflammation is an important process in the pathogenesis of migraine. It has been shown that the molecules of visinin-like protein 1 (Vilip-1), YKL-40, lipocalin-2 and interleukin (IL)-23 play a role in the inflammatory process. Our aim is to investigate the role of this molecule in the metabolic pathway of migraine disease.

METHODS

Fifty migraine patients with and without aura in the interictal period were included in the study. Vilip-1, YKL-40, lipocalin-2, and IL-23 levels were measured by ELISA method.

RESULTS

Serum vilip-1, YKL-40, lipocalin-2, and IL-23 levels were found to be significantly higher in migraine patients compared to the control group. We found that this molecule increased significantly in migraine subgroups compared to the control group (p < 0.001). A positive significant correlation was found between vilip-1 level and YKL-40 and lipocalin-2 levels in migraine patients. In addition, a positive correlation was observed between visual analogue scale score, number of days with pain and vilip-1 level (p < 0.01). The results of our study showed that activation of inflammatory mediators may play a role in the pathogenesis of migraine disease. In addition, our study is valuable in that inflammatory molecules are high in the interictal period and these biomarkers have never been analyzed in migraine patients. However, we still believe that larger studies are needed to explain the role of vilip-1, YKL-40, lipocalin-2, and IL-23 in the molecular mechanism of migraine disease.

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.

Chitinase-3-like Protein 1 (YKL-40): A New Biomarker of Inflamma-tion in Pyoderma Gangrenosum

Pyoderma gangrenosum (PG) is a rare, neutrophil-ic dermatosis with unclear aetiopathology, considered as an autoinflammatory disease, associated with other immune-mediated disorders. Chitinase-3-like protein 1 (YKL-40) is an inflammatory biomarker secreted by a wide variety of cells, including neutrophils. To evaluate YKL-40 serum level in relation to clinicopathological data, 48 patients with PG and 40 healthy controls were enrolled in the study. Skin lesions were measured to calculate the affected area. Inflammatory parameters (C-reactive protein, white blood cell count with neutrophils) were determined from blood samples. YKL-40 and IL-6 levels were measured in serum by enzyme-linked immunosorbent assay. YKL-40 serum level was significantly higher in patients with PG than in controls (58.4 vs 36.4 ng/ml, respectively; p < 0.00001). The positive correlation between YKL-40 level and IL-6 level was observed (r=0.48, p = 0.0006) along with a trend towards significance of relationship between YKL-40 level and C-reactive protein (r=0.28, p = 0.052). YKL-40 can be considered a valuable biomarker of inflammation in PG.

The Pathogenesis and Clinical Management of Stricturing Crohn Disease

Stricturing of the gastrointestinal tract is a common complication in Crohn disease and is a significant cause of morbidity and mortality among this population. The inflammatory process initiates fibrosis, leading to aberrant wound healing and excess deposition of extracellular matrix proteins. Our understanding of this process has grown and encompasses cellular mechanisms, epigenetic modifications, and inherent genetic predisposition toward fibrosis. Although medications can improve inflammation, there is still no drug to attenuate scar formation. As such, management of stricturing disease requires a multidisciplinary and individualized approach including medical management, therapeutic endoscopy, and surgery. This review details the current understanding regarding the pathogenesis, detection, and management of stricturing Crohn disease.

Fibrotic Strictures in Crohn's Disease: Mechanisms and Predictive Factors

Fibrotic strictures are one of the most severe complications of Crohn's Disease (CD). They occur in about 50% of patients at five years and in 70% at ten years of the diagnosis. The only treatment available for symptomatic fibrotic strictures is surgical resection and endoscopic dilation. Both strategies are associated with a high rate of recurrence, and with multiple surgical resections, which pose the threat of surgical morbidity and short bowel syndrome. Therefore, it is crucial to identify, early, the patients more prone to develop intestinal fibrosis to intensify follow-ups, switch to more aggressive treatments, and suggest lifestyle modifications. Scarce data are available concerning biomarkers and genetic determinants to predict which patient will develop intestinal fibrosis. Biologic or clinical markers would be useful to determine this subgroup of CD patients and to predict the onset of intestinal fibrosis and, ideally, its severity. Furthermore, the identification of environmental risk factors may suggest lifestyle changes aimed at modifying the natural course, thus decreasing the risk of complicated CD. In this review, we will critically revise clinical, environmental, genetic, and serologic factors that have been associated with a complicated CD course with a particular focus on the fibrostenosing phenotype and their possible implications as predictive factors of intestinal fibrosis.

A Review of Selected IBD Biomarkers: From Animal Models to Bedside

Inflammatory bowel disease (IBD) is a dysregulated inflammatory condition induced by multiple factors. The etiology of IBD is largely unknown, and the disease progression and prognosis are variable and unpredictable with uncontrolled disease behavior. Monitoring the status of chronic colitis closely is challenging for physicians, because the assessment of disease activity and severity require invasive methods. Using laboratory biomarkers may provide a useful alternative to invasive methods in the diagnosis and management of IBD. Furthermore, patients with ulcerative colitis or Crohn’s disease are also at risk of developing cancer. Annual colonoscopies can help lower the risk for developing colorectal cancer. However, laboratory biomarkers may also be helpful as non-invasive indicators in predicting treatment responses, improving prognosis, and predicting possible tumors. This review addresses selected laboratory biomarkers (including ANCA, chitinase 3-like 1, S100A12/RAGE, calprotectin, and TNF/TNFR2), which are identified by utilizing two well-accepted animal models of colitis, dextran sodium sulfate-induced and T cell receptor alpha knockout colitis models. In addition to being useful for monitoring disease severity, these biomarkers are associated with therapeutic strategies. The factors may regulate the initiation and perpetuation of inflammatory factors in the gut.

Macrophages as a source of fibrosis biomarkers for non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) are becoming major liver diseases worldwide. Liver fibrosis and cirrhosis are among the most significant risk factors of hepatocellular carcinoma (HCC) and associated with the long-term prognosis of NAFLD patients. To stratify the risk of HCC in NAFLD patients clinically, the discovery of non-invasive fibrosis markers is needed urgently. Liver macrophages play critical roles in the regulation of inflammation and fibrosis by interacting with hepatic stellate cells (HSCs) and other immune cells. Thus, it is rational to explore feasible biomarkers for liver fibrosis by focusing on macrophage-related factors. We examined serum factors comprehensively in multiple cohorts of NAFLD/NASH patients to determine whether they were correlated with the biopsy-proven fibrosis stage. We found that the serum levels of interleukin (IL)-34, YKL-40 and soluble Siglec-7 (sSiglec7) were closely associated with liver fibrosis and served as diagnostic biomarkers in patients with NAFLD/NASH. In the NAFLD liver, IL-34 was produced by activated fibroblasts, and YKL-40 and sSiglec-7 were secreted from macrophages. The sensitivity and specificity of these markers to detect advanced liver fibrosis varied, supporting the notion that the combination of these markers with other modalities is an option for clinical application.

CSF levels of HoxB3 and YKL-40 may predict conversion from clinically isolated syndrome to relapsing remitting multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) often initiates with an acute episode of neurological disturbance, known as clinically isolated syndrome (CIS). There is an unmet need for biomarkers that differentiate patients who will convert to MS and who will remain as CIS after the first attack.

METHODS

First attack serum and cerebrospinal fluid (CSF) samples of 33 CIS patients were collected and these patients were divided as those who converted to MS (CIS-MS, n=17) and those who continued as CIS (CIS-CIS, n=16) in a 3-year follow-up period. Levels of homeobox protein Hox-B3 (HoxB3) and YKL-40 were measured by ELISA in samples of CIS-CIS, CIS-MS, relapsing remitting MS (RRMS) patients (n=15) and healthy controls (n=20).

RESULTS

CIS-CIS patients showed significantly reduced CSF levels of YKL-40 and increased serum/CSF levels of HoxB3 compared with CIS-MS and RRMS patients. CIS-MS and RRMS patients had comparable YKL-40 and HoxB3 level profiles. Receiver operating characteristic (ROC) curve analysis showed the highest sensitivity for CSF HoxB3 measurements in prediction of CIS-MS conversion. Kaplan-Meier analysis demonstrated that CIS patients with lower CSF HoxB3 (<3.678 ng/ml) and higher CSF YKL-40 (>654.9 ng/ml) displayed a significantly shorter time to clinically definite MS.

CONCLUSION

CSF levels of HoxB3 and YKL-40 appear to predict CIS to MS conversion, especially when applied in combination. HoxB3, which is a transcription factor involved in immune cell activity, stands out as a potential candidate molecule with biomarker capacity for MS.

The expression levels of CHI3L1 and IL15Rα correlate with TGM2 in duodenum biopsies of patients with celiac disease

OBJECTIVE AND DESIGN

Celiac disease (CD) is an intestinal inflammatory disorder of the small intestine. Gliadins are a component of gluten and there are three main types (α, γ, and ω). Recent studies indicate that gliadin peptides are able to activate an innate immune response. IL15 is a major mediator of the innate immune response and is involved in the early alteration of CD mucosa. The chitinase molecules are highly expressed by the innate immune cells during the inflammatory processes.

MATERIAL OR SUBJECTS

We analyzed several microarray datasets of PBMCs and duodenum biopsies of CD patients and healthy control subjects (HCs). We verified the modulation CHI3L1 in CD patients and correlated the expression levels to the IL15, IL15Rα, TGM2, IFNγ, and IFNGR1/2. Duodenal biopsy samples belonged to nine active and nine treated children patients (long-term effects of gliadin), and 17 adult CD patients and 10 adults HCs. We also selected 169 samples of PBMCs from 127 CD patients on adherence to a gluten-free diet (GFD) for at least 2 years and 44 HCs.

RESULTS

Our analysis showed that CHI3L1 and IL15Rα were significantly upregulated in adult and children's celiac duodenum biopsies. In addition, the two genes were correlated significantly both in children than in adults CD duodenum biopsies. No significant modulation was observed in PBMCs of adult CD patients compared to the HCs. The correlation analysis of the expression levels of CHI3L1 and IL15Rα compared to TGM showed significant values both in adults and in children duodenal biopsies. Furthermore, the IFNγ expression levels were positively correlated with CHI3L1 and IL15Rα. Receiver operating characteristic (ROC) analysis confirmed the diagnostic ability of CHI3L1 and IL15Rα to discriminate CD from HCs.

CONCLUSION

Our data suggest a role for CHI3L1 underlying the pathophysiology of CD and represent a starting point aiming to inspire new investigation that proves the possible use of CHI3L1 as a diagnostic factor and therapeutic target.

Serum biomarkers of fibrostenotic Crohn's disease: Where are we now?

Intestinal fibrosis and subsequent stricture formation are major clinical challenges in inflammatory bowel disease, resulting in an increased rate of operation and poor prognosis compared with those without. With the changing perception that intestinal fibrosis is irreversible to the point of view that it is reversible in recent years, various candidate serum biomarkers have been studied over the past decades, which may stratify patients based on their risks of developing stenosis and enable the detection of early stages of fibrosis. However, reliable and accurate biomarkers are still unavailable due to conflicting results and the lack of high-quality evidence. In this review we summarized the serum biomarkers that have been proposed for intestinal fibrosis in recent years, which includes gene polymorphisms or variants, epigenetic markers, extracellular matrix components, growth factors, and antibodies, aiming to provide clues for future research.

Serum Biomarkers for Inflammatory Bowel Disease

Background: Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic, inflammatory disorder of the gastrointestinal tract. As the novel therapeutic goal and biologicals are widely recognized, accurate assessment of disease and prediction of therapeutic response have become a crucial challenge in clinical practice. Also, because of the continuously rising incidence, convenient and economical methods of diagnosis and clinical assessment are urgently needed. Recently, serum biomarkers have made a great progress and become a focus in IBD study because they are non-invasive, convenient, and relatively inexpensive than are markers in biopsy tissue, stool, breath, and other body fluids.

Aims: To review the available data on serological biomarkers for IBD.

Methods: We searched PubMed using predefined key words on relevant literatures of serum biomarkers regarding diagnosis, evaluation of therapeutic efficacy, surveillance of disease activity, and assessment of prognosis for IBD.

Results: We reviewed serological biomarkers that are well-established and widely used (e.g., C-reactive protein), newly discovered biomarkers (e.g., cytokines, antibodies, and non-coding RNAs), and also recently advancements in serological biomarkers (e.g., metabolomics and proteomics) that are used in different aspects of IBD management.

Conclusions: With such a wealth of researches, to date, there are still no ideal serum biomarkers for IBD. Serum profiling and non-coding RNAs are just starting to blossom but reveal great promise for future clinical practice. Combining different biomarkers can be valuable in improving performance of disease evaluation.

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.

Identification of Chitinase-3-Like Protein 1 as a Novel Neutrophil Antigenic Target in Crohn's Disease

BACKGROUND AND AIMS

There is an increasing incidence of inflammatory bowel disease [IBD]. Autoimmune responses are involved in the pathophysiology of IBD, but their underlying pathways and target antigens have not yet been fully elucidated.

METHODS

Autoantigenic targets in IBD were identified after separation of whole cell proteins isolated from neutrophils using two-dimensional electrophoresis and matrix assisted laser desorption ionization - time of flight mass spectrometry-based protein identification of the spots that displayed Western blotting signals with anti-neutrophil cytoplasmic antibody-positive sera. The prevalence of IgG, IgA and secretory IgA [sIgA] to chitinase 3-like protein 1 [CHI3L1] was analysed by enzyme-linked immunosorbent assays using recombinant CHI3L1 in 110 patients with Crohn's disease [CD], 95 with ulcerative colitis [UC], 126 with coeliac disease [CeD] and 86 healthy controls [HCs].

RESULTS

The 18-glycosylhydrolase family member CHI3L1 was identified as a neutrophil autoantigenic target. CD patients displayed significantly higher levels of IgG to CHI3L1 than patients with UC and CeD (p < 0.0001, respectively). IgA and sIgA to CHI3L1 was significantly higher in CD than in UC, CeD and HCs [p < 0.0001, respectively]. IgA and sIgA to CHI3L1 demonstrated the highest prevalence in CD [25.5%, 28/110; and 41.8%%, 46/110] compared to HCs [2.3%, 2/86; and 4.7%%, 4/86; p = 0.0015 and p < 0.0001] and are associated with a more complicated progression of CD.

CONCLUSION

CHI3L1 is a novel neutrophil autoantigenic target in CD. IgA and sIgA to CHI3L1 may serve as novel markers for CD and may facilitate the serological diagnosis of IBD.

Can YKL-40 be an Inflammatory Biomarker in Vitamin D Deficiency?

Vitamin D deficiency is associated with several non-homeostatic conditions and/or diseases like inflammation, atherosclerosis, cardiovascular disease and mortality. YKL-40 is a glycoprotein, secreted by macrophages, neutrophils and different cell types and it is also associated with inflammation and pathological tissue remodeling. In this study, we aimed to evaluate relationship between the proinflammatory biomarkers YKL-40 and hs-CRP levels and vitamin D deficiency. Our study group includes 45 subjects with vitamin D deficiency (Group 1) (20 M, 25 F; mean age 37.72 ± 7.70 years) and 40 age and sex-matched healthy subjects with normal serum levels of vitamin D (Group 2) (19 M, 21 F; mean age 39.26 ± 7.41 years). Plasma 25 (OH) vitamin D levels were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Plasma YKL-40 analysis was performed by ELISA. Serum hs-CRP levels were measured by nephelometric method. Plasma vitamin D levels below 20 ng/mL were accepted as vitamin D deficiency. Although we could not find any significant differences by means of serum hs-CRP levels between Group 1 and Group 2 (2.21 (0.27-11.70); 1.79 (0.16-9.85) mg/L, p = 0.247), plasma YKL-40 levels were significantly higher in group 1 than group2 (70.47 (17.84-198.50); 47.14 (4.80-135.48) ng/mL, p = 0.047). In literature, vitamin D deficiency is associated with inflammation. In our study, we found similar hs-CRP levels between groups and higher YKL-40 levels in group 1. Vitamin D deficiency may be related to high YKL-40 levels in terms of causing chronic inflammation.

Targeting anti-fibrotic pathways in Crohn's disease - The final frontier?

Intestinal fibrosis with stricture formation affects up to half of patients with Crohn's disease (CD), resulting in impaired quality of life, increased risk of surgical intervention, and associated patient morbidity. The underlying pathophysiologic mechansisms responsible for initiating and perpetuating intestinal fibrosis are complex, dynamic, and implicate both inflammation-dependent and independent pathways. Previously thought to be an irreversible complication of long-standing inflammation unresponsive to medical therapy, fibrostenotic CD has been traditionally managed with endoscopic or surgical approaches. However, recent advances in our understanding of the humoral, cellular, and environmental pathways driving intestinal fibrosis has the potential to fundamentally change these management paradigms for CD-related strictures. Furthermore, the promise of fibrosis treatments in other organ systems has encouraged hope that anti-fibrotic treatment approaches for CD may be within reach. Here, we summarize the key breakthroughs in our molecular understanding of intestinal fibrosis, review current medical, endoscopic, and surgical treatment approaches to CD-related strictures, propose future directions for anti-fibrotic therapy in CD, and identify crucial research questions in this field that require additional investigation.

Chitinase-3-like protein 1 (YKL-40) is a biomarker of severity of joint involvement in psoriatic arthritis

INTRODUCTION

Psoriasis is an inflammatory disease of a complex pathogenesis and arthritis is one of its most common complications. The biological role of chitinase-3-like protein 1 remains unknown. It is suggested that this protein takes part in processes such as proliferation, inflammation and tissue remodelling.

AIM

To determine whether YKL-40 can be a useful biomarker in psoriatic arthritis.

MATERIAL AND METHODS

The study was performed on 42 patients with psoriatic arthritis: 28 men and 14 women, aged from 24 to 71 years. All patients met the diagnostic criteria (CASPAR) for psoriatic arthritis. The severity of psoriatic arthritis was assessed using 28-joint Disease Activity Score with CRP. The assessment of skin lesions was performed by Psoriasis Area and Severity Index (PASI) and, additionally, the Body Surface Area (BSA) was calculated. Blood samples were taken to measure the serum concentration of YKL-40, as well as C-reactive protein, erythrocyte sedimentation rate, white blood cell count and neutrophil count.

RESULTS

YKL-40 serum levels were significantly higher in patients with psoriatic arthritis, compared to the control group. Moreover, a significant positive correlation between the activity of psoriatic arthritis measured by DAS 28 and serum level of YKL-40 was found. There was a positive correlation between serum YKL-40 and BSA, as well as a distinct trend towards significance between YKL-40 and PASI score.

CONCLUSIONS

YKL-40 can be a useful biomarker for both diagnosing and monitoring joint involvement in psoriatic patients.

Chitinase-3-Like Protein 1 (YKL-40) Reflects the Severity of Symptoms in Atopic Dermatitis

Chitinase-3-like protein 1 (YKL-40) is suggested to be associated with type 2 T helper response and atopy. The aim of the study was the evaluation of serum YKL-40 level in atopic dermatitis. The study was performed on 59 patients: 27 males and 32 females, aged from 18 to 64 years. The severity of the disease was assessed by the SCORAD and objective SCORAD indexes. The severity of pruritus was measured by the visual analogue scale. Blood samples were taken to examine serum level of YKL-40, total IgE level, C-reactive protein level, white blood cell count, and neutrophil count. YKL-40 serum levels were significantly higher in patients with atopic dermatitis compared to the controls. There was a positive correlation between YKL-40 concentration and SCORAD, objective SCORAD, and pruritus. This study has shown that YKL-40 serum level is increased in patients with atopic dermatitis and reflects the severity of symptoms.

Mechanisms, Management, and Treatment of Fibrosis in Patients With Inflammatory Bowel Diseases

In the last 10 years, we have learned much about the pathogenesis, diagnosis, and management of intestinal fibrosis in patients with inflammatory bowel diseases. Just a decade ago, intestinal strictures were considered to be an inevitable consequence of long-term inflammation in patients who did not respond to anti-inflammatory therapies. Inflammatory bowel diseases-associated fibrosis was seen as an irreversible process that frequently led to intestinal obstructions requiring surgical intervention. This paradigm has changed rapidly, due to the antifibrotic approaches that may become available. We review the mechanisms and diagnosis of this serious complication of inflammatory bowel diseases, as well as factors that predict its progression and management strategies.

Serum YKL-40 as predictor of outcome in hypersensitivity pneumonitis

YKL-40, a chitinase-like protein mainly secreted by macrophages, neutrophils and epithelial cells, is increased in patients with idiopathic interstitial pneumonia and sarcoidosis. We aimed to investigate the role of YKL-40 as a biomarker in hypersensitivity pneumonitis (HP).

72 HP patients, 100 interstitial lung disease (ILD) controls and 60 healthy controls were studied. YKL-40 was measured by ELISA in serum and bronchoalveolar lavage fluid (BALF) at baseline and follow-up. The relationship between YKL-40 levels, clinical variables and disease outcome was evaluated.

Baseline serum YKL-40 levels were significantly higher in HP patients than in healthy controls (p<0.001), but lower than in patients with other ILDs. Baseline BALF YKL-40 levels in HP patients were the highest among ILD patients. In HP patients, serum YKL-40 correlated with the diffusing capacity of the lung for carbon monoxide at baseline (p<0.01) and over time (p<0.001). HP patients whose disease progressed or who died had higher baseline YKL-40 levels than those who remained stable and survived (p<0.001). At a cut-off of 119 ng·mL−1, the baseline serum YKL-40 level predicted disease progression (hazard ratio 6.567; p<0.001), and at a cut-off of 150 ng·mL−1 was associated with mortality (hazard ratio 9.989; p<0.001).

Serum YKL-40 may be a useful prognostic biomarker in HP patients.

Serum YKL-40 as a marker of liver fibrosis in patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic non-viral liver disease. YKL-40, chitinase-like protein expressed in multiple tissues including liver, is involved in cell proliferation, inflammation and remodeling of the extracellular matrix. The aim of this study was to assess whether serum YKL-40 levels are associated with liver fibrosis in NAFLD patients. Serum YKL-40 levels were quantified in 111 NAFLD patients and 23 HCC patients with NAFLD. To identify the source of YKL-40, immunofluorescence staining of liver specimens from NAFLD patients was performed. Serum YKL-40 levels in NAFLD patients increased in accordance with the progression of liver fibrosis. Multivariate analysis revealed that YKL-40 was one of the independent factors significantly associated with severe fibrosis (F3-4). We established a new predictive model for fibrosis of NAFLD, using logistic regression analysis: YKL-40 based fibrosis score = −0.0545 + type IV collagen 7s * 0.3456 + YKL-40 * 0.0024. Serum YKL-40 levels of HCC patients with non-cirrhotic NAFLD were significantly higher than those without HCC. Immunofluorescence staining showed that YKL-40 was expressed by macrophages in liver tissue of NAFLD patients. In conclusion, macrophage-derived YKL-40 is a feasible biomarker of liver fibrosis in NAFLD patients.

European Crohn's and Colitis Organisation Topical Review on Prediction, Diagnosis and Management of Fibrostenosing Crohn's Disease

This ECCO topical review of the European Crohn's and Colitis Organisation [ECCO] focused on prediction, diagnosis, and management of fibrostenosing Crohn's disease [CD]. The objective was to achieve evidence-supported, expert consensus that provides guidance for clinical practice.

Biomarkers of intestinal fibrosis - one step towards clinical trials for stricturing inflammatory bowel disease

Intestinal fibrosis, caused by an excessive deposition of extracellular matrix components, and subsequent stricture development are a common complication of inflammatory bowel disease. However, currently there are no biomarkers which reliably predict the risk of developing intestinal strictures or identify early stages of fibrosis prior to clinical symptoms. Candidate biomarkers of intestinal fibrosis, including gene variants (i.e. nucleotide-binding oligomerization domain-2 gene), serum microRNAs (miR-19, miR-29), serum extracellular matrix proteins (i.e. collagen, fibronectin) or enzymes (i.e. tissue inhibitor of matrix metalloproteinase-1), serum growth factors (i.e. basic fibroblast growth factor, YKL-40), serum anti-microbial antibodies (i.e. anti-Saccharomyces cerevisiae) and circulating cells (i.e. fibrocytes) have shown conflicting results on relatively heterogeneous patients' cohorts, and none of them was proven to be strictly specific for fibrostenosis, but rather predictive of a disease disabling course. In this review we critically reassess the diagnostic and prognostic value of serum biomarkers of intestinal fibrosis in inflammatory bowel disease.

Perspectives for Monocyte/Macrophage-Based Diagnostics of Chronic Inflammation

Low-grade chronic inflammation underlies the development of the most dangerous cardiometabolic disorders including type 2 diabetes and its vascular complications. In contrast to acute inflammation induced by bacteria and viruses, chronic inflammation can be driven by abnormal reaction to endogenous factors, including Th2 cytokines, metabolic factors like advanced glycation end products (AGEs), modified lipoproteins, or hyperglycemia. The key innate immune cells that recognize these factors in blood circulation are monocytes. Inflammatory programming of monocytes which migrate into tissues can, in turn, result into generation of tissue macrophages with pathological functions. Therefore, determination of the molecular and functional phenotype of circulating monocytes is a very promising diagnostic tool for the identification of hidden inflammation, which can precede the development of the pathology. Here we propose a new test system for the identification of inflammatory programming of monocytes: surface biomarkers and ex vivo functional system. We summarize the current knowledge about surface biomarkers for monocyte subsets, including CD16, CCR2, CX3CR1, CD64, stabilin-1 and CD36, and their association with inflammatory human disorders. Furthermore, we present the design of an ex vivo monocyte-based test system with minimal set of parameters as a potential diagnostic tool for the identification of personalized inflammatory responses.

Non-invasive assessment of liver fibrosis: Between prediction/prevention of outcomes and cost-effectiveness

The assessment of the fibrotic evolution of chronic hepatitis has always been a challenge for the clinical hepatologist. Over the past decade, various non-invasive methods have been proposed to detect the presence of fibrosis, including the elastometric measure of stiffness, panels of clinical and biochemical parameters, and combinations of both methods. The aim of this review is to analyse the most recent data on non-invasive techniques for the evaluation of hepatic fibrosis with particular attention to cost-effectiveness. We searched for relevant studies published in English using the PubMed database from 2009 to the present. A large number of studies have suggested that elastography and serum markers are useful techniques for diagnosing severe fibrosis and cirrhosis and for excluding significant fibrosis in hepatitis C virus patients. In addition, hepatic stiffness may also help to prognosticate treatment response to antiviral therapy. It has also been shown that magnetic resonance elastography has a high accuracy for staging and differentiating liver fibrosis. Finally, studies have shown that non-invasive methods are becoming increasingly precise in either positively identifying or excluding liver fibrosis, thus reducing the need for liver biopsy. However, both serum markers and transient elastography still have “grey area” values of lower accuracy. In this case, liver biopsy is still required to properly assess liver fibrosis. Recently, the guidelines produced by the World Health Organization have suggested that the AST-to-platelet ratio index or FIB-4 test could be utilised for the evaluation of liver fibrosis rather than other, more expensive non-invasive tests, such as elastography or FibroTest.

RelB/p50 complexes regulate cytokine-induced YKL-40 expression

The secreted protein, YKL-40, has been proposed as a biomarker of a variety of human diseases characterized by ongoing inflammation, including chronic neurologic pathologies such as multiple sclerosis and Alzheimer's disease. However, inflammatory mediators and the molecular mechanism responsible for enhanced expression of YKL-40 remained elusive. Using several mouse models of inflammation, we now show that YKL-40 expression correlated with increased expression of both IL-1 and IL-6. Furthermore, IL-1 together with IL-6 or the IL-6 family cytokine, oncostatin M, synergistically upregulated YKL-40 expression in both primary human and mouse astrocytes in vitro. The robust cytokine-driven expression of YKL-40 in astrocytes required both STAT3 and NF-κB binding elements of the YKL-40 promoter. In addition, YKL-40 expression was enhanced by constitutively active STAT3 and inhibited by dominant-negative IκBα. Surprisingly, cytokine-driven expression of YKL-40 in astrocytes was independent of the p65 subunit of NF-κB and instead required subunits RelB and p50. Mechanistically, we show that IL-1-induced RelB/p50 complex formation was further promoted by oncostatin M and that these complexes directly bound to the YKL-40 promoter. Moreover, we found that expression of RelB was strongly upregulated during inflammation in vivo and by IL-1 in astrocytes in vitro. We propose that IL-1 and the IL-6 family of cytokines regulate YKL-40 expression during sterile inflammation via both STAT3 and RelB/p50 complexes. These results suggest that IL-1 may regulate the expression of specific anti-inflammatory genes in nonlymphoid tissues via the canonical activation of the RelB/p50 complexes.

New therapeutic avenues for treatment of fibrosis: can we learn from other diseases?

Crohn's disease (CD) is characterized by the frequent occurrence of complications, such as fibrotic strictures and subsequently the need for CD-related surgery. Chronic or recurrent inflammation is generally regarded to be a necessary precondition for the initiation of intestinal fibrosis. In this view, fibrosis is a pathologically augmented healing response to inflammation-induced mucosal tissue destruction and injury. At present, there are no approved or effective medical therapies aimed specifically at fibrosis or stricture in IBD. Indirect benefits may occur from anti-inflammatory therapies, although there is no consensus on this. Therapy for fibrosis is complicated by the fact that a wound-healing response is essential in CD and ulcerative colitis. Several pharmaceutical companies are now working on the therapy of fibrosis in other diseases. Strategies interfering with TGF-β expression and activation are promising. Pirfenidone has been studied in several clinical trials. Further therapeutic options are second-generation and wide-spectrum tyrosine kinase inhibitors. These inhibit growth factor receptor signaling, thus reducing fibrosis in animal models and some patients with tumor-associated fibrosis. At present, the development of antifibrotic therapies takes place in other diseases such as lung and liver fibrosis. This is partially due to a lack of experimental models for gut fibrosis and the fact that reliable readouts (MRI, serum markers) in patients are lacking. It will be important to test the above-mentioned newly available treatment strategies in IBD to profit from progress in other fibrotic diseases.

Increased expression and possible role of chitinase 3-like-1 in a colitis-associated carcinoma model

AIM: To investigate the possible role of chitinase 3-like-1 (CHI3L1) in the progression of colitis-associated carcinoma (CAC).

METHODS: Thirty-four Balb/c mice were randomly assigned to five groups, including the control, CAC control, CAC + caffeine, colitis control and colitis + caffeine. Three animals were sacrificed every two weeks for blinded macroscopic inspection, histological analysis, and total RNA extraction. An immunofluorescent assay was performed using specimens from the colitis control and colitis + caffeine groups to investigate whether the protective effect of caffeine was associated with less oxidative DNA damage. In vitro, HT29 cells pre-stimulated with different concentrations of recombinant CHI3L1 protein and H₂O₂ were loaded with the DCFH-DA fluorescent probe to determine the effect of CHI3L1 on intracellular reactive oxygen species production.

RESULTS: CHI3L1 mRNA was increased during the progression of colon carcinogenesis. Tumors were mostly located in the distal end of the colon where the expression of CHI3L1 was higher than in the proximal colon. Caffeine-treated mice developed fewer tumors and milder inflammation than untreated mice. CHI3L1 protein increased reactive oxygen species in HT29 cells when exposed to H₂O₂.

CONCLUSION: Caffeine reduces tumor incidence by decreasing oxidative DNA damage. CHI3L1 may contribute to CAC by increasing reactive oxygen species production.

The serum YKL-40 level is associated with vascular injury and predicts proteinuria in nephrotic syndrome patients

AIM

Nephrotic syndrome (NS) is associated with an increased rate of cardiovascular events. The YKL-40 level is associated with atherosclerosis, endothelial dysfunction and proteinuria in renal and non-renal populations. The aim of this study was to investigate the relationships between the YKL-40 level and both vascular injury and proteinuria in NS patients.

METHODS

Sixty-nine NS patients and 20 healthy subjects were enrolled in the present study. The endothelial function was assessed according to the flow mediated dilatation (FMD) and the degree of arterial stiffness was determined based on the pulse wave velocity (PWV). The serum YKL-40 levels were measured using ELISA.

RESULTS

The YKL-40 levels and PWV values were higher and the FMD values were lower in the NS patients than in the healthy controls. However, the CA-IMT and LVEF levels were not statistically different between the two groups. The patients were divided into three groups with respect to the extent of proteinuria: the normoproteinuria group (n:18), non-nephrotic proteinuria group (n:33) and nephrotic proteinuria group (n:18). Consequently, the YKL-40 levels and PWV values were significantly increased and the FMD values were decreased in the nephrotic proteinuria group compared to that observed in both the non-nephrotic proteinuria and normoproteinuria groups. Furthermore, the YKL-40 level correlated with the FMD and PWV values in the NS patients. In addition, proteinuria correlated with the YKL-40, FMD, PWV, eGFR and fasting LDL cholesterol values in this patient group. Multivariate linear regression analyses showed that the YKL-40 and eGFR values were effective in predicting proteinuria in the NS patients.

CONCLUSIONS

The serum YKL-40 level is associated with endothelial dysfunction and increased arterial stiffness in NS patients and may be an indicator of the level of proteinuria in this patient population.

Serum YKL-40 concentrations are elevated and correlated with disease severity in patients with obstructive sleep apnea syndrome

Abstract Inflammation plays a critical role in the pathogenesis of obstructive sleep apnea syndrome (OSAS). YKL-40 is a novel biomarker of systemic inflammation. We aim to detect serum YKL-40 concentrations in OSAS patients and to clarify their relationship with clinical severity of the disease. We enrolled 159 OSAS patients and 104 healthy controls. The presence and severity of OSAS was assessed by Apnea-hypopnea index (AHI). Serum YKL-40 concentrations were detected by enzyme-linked immunosorbent assay (ELISA). We demonstrated that serum YKL-40 concentrations were significantly elevated in OSAS patients than those in controls. Multivariate logistic regression including all variables revealed that YKL-40 was the significant and independent predictor for the present of OSAS. In OSAS patients, there is a significant positive correlation between increments in serum YKL-40 concentrations and severity of OSAS. Serum YKL-40 concentrations were independently and significantly correlated with AHI scores. These results suggest that YKL-40 could be used as a potential biomarker for predicting the development and progression of OSAS.

The expression of chitinase 3-like 1: a novel prognostic predictor for hepatocellular carcinoma

OBJECTIVES

Chitinase 3-like 1 (CHI3L1) is associated with poor prognosis of various human cancers. However, the clinical and prognostic significance of CHI3L1 in hepatocellular carcinoma (HCC) is largely unknown. The aim of the present study is to investigate the expression of CHI3L1 in human HCC cell lines, clinical HCC specimens and its association with expressions of phosphorylated-Akt (p-Akt), E-cadherin and prognostic significance.

METHODS

The protein level of CHI3L1 in HCC cell lines was evaluated by western blot. The mRNA and protein levels of CHI3L1 in 19 self-paired HCC specimens were assessed by RT-PCR and western blot assays. The clinical and prognostic significance of CHI3L1 in 70 cases of HCC patients was determined by immunohistochemistry. In addition, expressions of p-Akt and E-cadherin were also assessed.

RESULTS

The protein level of CHI3L1 paralleled with increased malignant potential of HCC cell lines (P < 0.05). The mRNA and protein levels of CHI3L1 in HCC tissues were up-regulated compared with those in adjacent peritumoral tissues and further increased in tumors with metastasis (P < 0.05). Clinicopathological analysis showed that positive CHI3L1 expression was significantly associated with larger tumor size, capsular invasion, advanced TNM stages and status of metastasis (P = 0.035, 0.003, 0.023 and 0.003, respectively). Furthermore, CHI3L1 expression was positively correlated with high level of p-Akt (r = 0.293, P = 0.014), but inversely correlated with expression of E-cadherin (r = -0.267, P = 0.026). Additionally, Kaplan-Meier survival analysis showed that HCC patients with positive CHI3L1 expression had a worse overall survival and disease-free survival compared with those with negative CHI3L1 expression (P < 0.001, respectively). Multivariate analysis identified CHI3L1 as an independent prognostic predictor for overall survival and disease-free survival of HCC patients (P = 0.044 and 0.031, respectively).

CONCLUSIONS

CHI3L1 plays an essential role in HCC malignancies and may be served as a valuable prognostic biomarker for HCC patients.

YKL-40 protein is a marker of asthma

BACKGROUND

Gaining asthma control is still a challenge in a large number of patients. It could be facilitated by using biomarkers indicating the grade of inflammation and correlating with clinical picture. Chitinases and chitinase-like proteins play a role in Th2-type inflammation. Thus, they may be useful in diagnosing and monitoring of asthma.

OBJECTIVES

The aim of the study was to investigate the relevance of YKL-40 as a good biomarker of asthma, its control, and severity.

METHODS

Level of YKL-40 was determined by means of immunoassay in sera of 59 asthmatics (39 women, 20 men, aged 23-76 years) and 29 healthy controls (18 women, 11 men, aged 20-80 years). Asthma severity and control were assessed according to GINA guidelines. Differences between groups were compared with the use of Mann-Whitney's U-test. Correlations between variables were assessed with Pearson's test.

RESULTS

Symptoms of asthma were found to be controlled in 12 (20%), partly controlled in 17 (29%), and uncontrolled in 30 (51%) patients. YKL-40 levels were significantly higher, on average, in asthmatics compared to control group (median levels: 125.3 U and 84.1 U, respectively, p < .001). YKL-40 correlated with the number of blood eosinophils (r = 0.376, p = 0.05). However, no relations have been found between YKL-40 level and asthma severity, control, or total serum IgE (r = -0.05, p = .05).

CONCLUSION

YKL-40 seems to be a good marker of asthma. However, its level may not correlate with clinical outcome.

Utility of Serum YKL-40 as a Tumor-Specific Marker of Hepatobiliary Malignancies

BACKGROUND/AIMS

Serum YKL-40 has been linked to several human cancers. We investigated the potential role of serum YKL-40 as a marker of hepatobiliary malignancies.

METHODS

Archived serum samples of patients undergoing liver transplantation evaluation at the Mayo Clinic Rochester were used to measure YKL-40 levels. Patients were divided into three groups: hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), and end-stage liver disease (ESLD) without malignancies. The Model for ESLD (MELD) score was used to quantify the severity of liver disease.

RESULTS

The median serum YKL-40 level was highest in the ESLD group at 296 ng/mL, compared to 259 ng/mL in the HCC group and 80 ng/mL in the CCA group (p<0.01). There was a significant correlation between the MELD score and serum YKL-40 level (r=0.50, p<0.01). In a multivariate analysis, there was no significant difference in serum YKL-40 level between ESLD and HCC. CCA was associated with lower YKL-40 levels, a finding that was attributable to a lower prevalence of cirrhosis.

CONCLUSIONS

The serum YKL-40 level has little utility as a cross-sectional screening tool for hepatobiliary malignancies, namely HCC and CCA. The role of YKL-40 as a surveillance marker in the follow-up of individual patients remains to be determined.

YKL-40-A Protein in the Field of Translational Medicine: A Role as a Biomarker in Cancer Patients?

YKL-40 is a 40 kDa glycoprotein produced by cancer cells, inflammatory cells and stem cells. It probably has a role in cell proliferation and differentiation, inflammation, protection against apoptosis, stimulation of angiogenesis, and regulation of extracellular tissue remodelling. Plasma levels of YKL-40 are often elevated in patients with localized or advanced cancer compared to age-matched healthy subjects. Several studies have demonstrated that high plasma YKL-40 is an independent prognostic biomarker of short survival in patients with different types of cancer. However, there is not yet sufficient data to support determination of plasma YKL-40 outside research projects as a biomarker for screening of gastrointestinal cancer and determination of treatment response and poor prognosis before or during treatment and follow-up. Plasma YKL-40 is also elevated in patients with other diseases than cancer, e.g., severe infections, cardiovascular disease, diabetes, chronic obstructive lung disease, asthma, liver fibrosis and rheumatoid arthritis. Co-morbidity should therefore always be considered in patients with cancer, since other sources than cancer cells can increase plasma YKL-40 levels. Future focused translational research projects combining basic and clinical research are needed in a joint effort to answer questions of the complex function and regulation of YKL-40 and the question if plasma YKL-40 is a clinical useful biomarker in patients with cancer.

Cerebrospinal fluid chitinase 3-like 1 levels are associated with conversion to multiple sclerosis

In most patients with multiple sclerosis, the disease initiates with a first attack or clinically isolated syndrome. At this phase, magnetic resonance imaging is an important predictor of conversion to multiple sclerosis. With the exception of oligoclonal bands, the role of other biomarkers in patients with clinically isolated syndrome is controversial. In the present study, we aimed to identify proteins associated with conversion to multiple sclerosis in patients with clinically isolated syndrome. We applied a mass spectrometry-based proteomic approach (isobaric labelling) to previously collected pooled cerebrospinal fluid samples from patients with clinically isolated syndrome, who subsequently converted to clinically definite multiple sclerosis (n=30) and patients who remained as having clinically isolated syndrome (n=30). Next, three of the most represented differentially expressed proteins, i.e. ceruloplasmin, vitamin D-binding protein and chitinase 3-like 1 were selected for validation in individual cerebrospinal fluid samples by enzyme-linked immunosorbent assay. Only chitinase 3-like 1 was validated and cerebrospinal fluid levels were increased in patients who converted to clinically definite multiple sclerosis compared with patients who continued as clinically isolated syndrome (P=0.00002) and controls (P=0.012). High cerebrospinal fluid levels of chitinase 3-like 1 significantly correlated with the number of gadolinium enhancing lesions and the number of T2 lesions observed in brain magnetic resonance imaging scans performed at baseline, and were associated with disability progression during follow-up and shorter time to clinically definite multiple sclerosis (log-rank P-value=0.003). Cerebrospinal fluid chitinase 3-like 1 levels were also measured in a second validation clinically isolated syndrome cohort and found to be increased in patients who converted to multiple sclerosis compared with patients who remained as having clinically isolated syndrome (P=0.018). Our results indicate that patients who will convert to clinically definite multiple sclerosis could be distinguished from those patients who will remain as clinically isolated syndrome by proteomic analysis of cerebrospinal fluid samples. Although protein levels are also increased in other disorders characterized by chronic inflammation, chitinase 3-like 1 may serve as a prognostic biomarker for conversion to multiple sclerosis and development of disability which may help to improve the understanding of the aetiopathogenesis in the early stages of multiple sclerosis.

YKL-40 identified by proteomic analysis as a biomarker of sepsis

To investigate changes in protein expression by proteomic analysis in the sera of patients with sepsis and to identify new biomarkers of sepsis. A total of 45 consecutive patients with severe sepsis or septic shock (sepsis group), 22 healthy volunteers, and 23 patients undergoing off-pump coronary artery bypass grafting (control group). Serum samples from eight patients of each group underwent proteomic analysis involving removal of 12 major proteins and subsequent reversed-phase high-performance liquid chromatography fractionation and one-dimensional electrophoresis. The intensity of 41 bands (with 12 proteins identified) increased and that of 42 bands (with 22 proteins identified) decreased in the sepsis group. Results of proteomic analysis successfully validated by Western blotting and/or enzyme-linked immunosorbent assay for three proteins (YKL-40, lipocalin 2, and S100A9) increased in the sepsis group as well as two proteins (retinol-binding protein, vitamin D-binding protein) decreased. Serum YKL-40 levels (sYKL-40) on intensive care unit (ICU) admission were assessed by enzyme-linked immunosorbent assay between the two groups; resulting YKL-40 was significantly higher in the sepsis group (P < 0.001). Furthermore, sYKL-40 on ICU admission was significantly higher in patients with positive blood culture (P < 0.005), patients with septic shock (P < 0.05), and patients requiring continuous hemodiafiltration (P < 0.05) or hydrocortisone replacement therapy (P < 0.005) during subsequent treatment. A positive correlation between sYKL-40 and blood IL-6 level on ICU admission was noted in the sepsis group (r = 0.465, P < 0.01). YKL-40 identified by proteomic analysis is considered as a biomarker of sepsis. However, further investigation is needed to clarify its roles and clinical usefulness as a biomarker.

Plasma YKL-40: a potential new cancer biomarker?

YKL-40, a 40-kDa secreted glycoprotein, with its gene located on chromosome 1q32.1, is produced by cancer cells and inflammatory cells and has a role in inflammation, cell proliferation, differentiation, protection against apoptosis, stimulation of angiogenesis and regulation of extracellular tissue remodeling. Plasma levels of YKL-40 are elevated in a subgroup of patients with primary or advanced cancer compared with age-matched healthy subjects, but also in patients with many different diseases characterized by inflammation. Elevated plasma YKL-40 levels are an independent prognostic biomarker of short survival. There is still insufficient evidence to support its value outside of clinical trials as a screening tool, prognosticator of survival, predictor of treatment response and as a monitoring tool in the routine management of individual patients with cancer or diseases characterized by inflammation. Large prospective, longitudinal clinical cancer studies are needed to determine if plasma YKL-40 is a new cancer biomarker, or is mainly a biomarker of inflammation.

Plasma YKL-40 is elevated in patients with recurrent atrial fibrillation after catheter ablation

AIM

To study plasma YKL-40 in patients with atrial fibrillation (AF) treated with radiofrequency (RF) catheter ablation and to assess the predictive role of plasma YKL-40 and its changes after restoration of sinus rhythm (SR).

METHODS

Forty-six patients (mean age 55 years, range 31-81) with paroxysmal/persistent AF were treated with RF catheter ablation; Holter monitoring for 14 days was performed before ablation and after 3 months. Recurrent symptomatic AF or atrial tachycardia >10 min was considered failure, and the patients were offered a second ablation session. YKL-40 was determined in plasma samples taken prior to ablation and at follow-up visits up to 12 months after ablation.

RESULTS

After a maximum of two ablations, 19 patients (41%) had SR without recurrence of AF after 12 months. The patients with no recurrence of AF had significantly lower baseline plasma levels of YKL-40 prior to ablation compared to patients with recurrence of AF (31 vs. 62 microg/l, P = 0.029). Plasma YKL-40 was not an independent predictor of recurrence of AF after ablation. No significant changes in plasma YKL-40 levels were seen from baseline to follow-up at 12 months.

CONCLUSION

In patients with paroxysmal or persistent AF treated with catheter ablation, high plasma YKL-40 before ablation is associated with recurrence of AF.