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

Significance of chitinase-3-like protein 1 in the pathogenesis of inflammatory diseases and cancer

Chitinase-3-like protein 1 (CHI3L1) is a secreted glycoprotein that mediates inflammation, macrophage polarization, apoptosis, and carcinogenesis. The expression of CHI3L1 is strongly upregulated by various inflammatory and immunological diseases, including several cancers, Alzheimer's disease, and atherosclerosis. Several studies have shown that CHI3L1 can be considered as a marker of disease diagnosis, prognosis, disease activity, and severity. In addition, the proinflammatory action of CHI3L1 may be mediated via responses to various proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and interferon-γ. Therefore, CHI3L1 may contribute to a vast array of inflammatory diseases. However, its pathophysiological and pharmacological roles in the development of inflammatory diseases remain unclear. In this article, we review recent findings regarding the roles of CHI3L1 in the development of inflammatory diseases and suggest therapeutic approaches that target CHI3L1.

Osteoprotegerin, Chitinase 3-like Protein 1, and Cardiotrophin-1 as Potential Biomarkers of Obstructive Sleep Apnea in Adults-A Case-Control Study

Obstructive sleep apnea (OSA) is a prevalent, underdiagnosed disease and is considered a risk factor for cardiovascular diseases, depression, accidents, and stroke. Recent clinical practice guidelines for OSA expressed the need for a new clinical tool that establishes the Apnea-Hypopnea Index (AHI) to determine the disease burden. The serum and plasma concentrations of Osteoprotegerin (OPG), Chitinase 3-like protein 1 (YKL-40), and Cardiotrophin-1 (CT-1) in 80 subjects-52 OSA patients, 27 moderate (15 ≤ AHI ˂ 30) and 25 severe (AHI ≥ 30), and 28 non-OSA controls (AHI 0-5)-were determined. Moreover, the Total Oxidative Status (TOS), Total Antioxidative Status (TAS), and Oxidative Stress Index (OSI) were assessed in the serum and plasma to evaluate whether the severity of OSA and the concentrations of OPG, YKL-40, and CT-1 correlate with the oxidative/reductive status. The serum and plasma concentrations of YKL-40 and CT-1 were higher in the OSA group, whereas the serum and plasma concentrations of OPG were lower compared to the control group. The concentrations of OPG, YKL-40, and CT-1 in the serum and plasma correlated with AHI; however, a better correlation of the concentrations was obtained for the above-mentioned proteins in the plasma. The concentrations of YKL-40 and CT-1 in the serum and OPG in the plasma show better diagnostic capabilities for moderate and severe OSA than the concentrations of YKL-40 and CT-1 in the plasma and the concentrations of OPG in the serum.

Obstructive Sleep Apnea and Its Treatment in Aging: Effects on Alzheimer's disease Biomarkers, Cognition, Brain Structure and Neurophysiology

Here we review the impact of obstructive sleep apnea (OSA) on biomarkers of Alzheimer's disease (AD) pathogenesis, neuroanatomy, cognition and neurophysiology, and present the research investigating the effects of continuous positive airway pressure (CPAP) therapy. OSA is associated with an increase in AD markers amyloid-β and tau measured in cerebrospinal fluid (CSF), by Positron Emission Tomography (PET) and in blood serum. There is some evidence suggesting CPAP therapy normalizes AD biomarkers in CSF but since mechanisms for amyloid-β and tau production/clearance in humans are not completely understood, these findings remain preliminary. Deficits in the cognitive domains of attention, vigilance, memory and executive functioning are observed in OSA patients with the magnitude of impairment appearing stronger in younger people from clinical settings than in older community samples. Cognition improves with varying degrees after CPAP use, with the greatest effect seen for attention in middle age adults with more severe OSA and sleepiness. Paradigms in which encoding and retrieval of information are separated by periods of sleep with or without OSA have been done only rarely, but perhaps offer a better chance to understand cognitive effects of OSA than isolated daytime testing. In cognitively normal individuals, changes in EEG microstructure during sleep, particularly slow oscillations and spindles, are associated with biomarkers of AD, and measures of cognition and memory. Similar changes in EEG activity are reported in AD and OSA, such as "EEG slowing" during wake and REM sleep, and a degradation of NREM EEG microstructure. There is evidence that CPAP therapy partially reverses these changes but large longitudinal studies demonstrating this are lacking. A diagnostic definition of OSA relying solely on the Apnea Hypopnea Index (AHI) does not assist in understanding the high degree of inter-individual variation in daytime impairments related to OSA or response to CPAP therapy. We conclude by discussing conceptual challenges to a clinical trial of OSA treatment for AD prevention, including inclusion criteria for age, OSA severity, and associated symptoms, the need for a potentially long trial, defining relevant primary outcomes, and which treatments to target to optimize treatment adherence.

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.

Evaluation of preoperative and postoperative serum interleukin-6, interleukin-8, tumor necrosis factor α and raftlin levels in patients with obstructive sleep apnea

BACKGROUND

Raftlin is a large, major lipid raft protein of cell membranes. Raftlin levels have not been previously examined in patients with obstructive sleep apnea (OSA). Our study aimed to evaluate the changes in raftlin, interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNFα) values from the preoperative state to the third month postoperatively in patients undergoing expansion sphincter pharyngoplasty for OSA.

METHODS

Of 60 patients, 10 patients had mild OSA (AHI 5-14), 10 moderate (AHI 15-29), 10 severe (AHI ≥ 30), and 30 with AHI < 5 formed a control group. Preoperatively and at 3 months post-operatively, IL-6, IL-8, TNFα, and raftlin values were measured.

RESULTS

Preoperatively, mean raftlin levels were 914.4 ± 62.7 pg/mL for controls, 910.0 ± 42.5 pg/mL in mild, 1000.5 ± 63.3 pg/mL in moderate, and 1386.3 ± 101.4 pg/mL in severe groups, with moderate and severe groups significantly elevated compared to controls (p < 0.001). Preoperatively to 3 months post-operatively, raftlin levels decreased significantly in each OSA group (p < 0.05). Levels of IL-6, IL-8 and TNFα followed similar patterns at baseline and after surgical intervention.

CONCLUSIONS

Raftlin levels at the third postoperative month decreased significantly compared with preoperative levels in parallel with other markers of inflammation.

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

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

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.

PAŞAOĞLU Ö, KESKİN Ç, ARINSOY T, B. DERİCİ Ü. Relationship between plasma YKL-40 levels and endothelial dysfunction in chronic kidney disease

Background/aim

We aimed to evaluate the relationship between YKL-40 and endothelial dysfunction in chronic kidney disease.

Materials and methods

Twenty-nine hemodialysis patients, 101 patients with nondialytic (stage 2, 3, 4, and 5 ND) chronic kidney disease (CKD), and 38 healthy individuals as a control group were included. YKL-40 levels were measured by ELISA. Endothelial dysfunction was indirectly measured by flow-mediated dilatation percentage (FMD) in the brachial artery.

Results

YKL-40 levels were higher in CKD patients than controls and highest in HD patients (P = 0.001). FMD values were lower in nondialytic CKD patients and lowest in HD patients (P = 0.001). YKL-40 negatively correlated with eGFR and FMD values (r = –0.674 and r = –0.471, respectively).

Conclusion

This study shows that YKL-40 increases with CKD stage and is negatively correlated with FMD measurements.