Circulating CXCL16 is not related to circulating oxLDL in patients with rheumatoid arthritis

Chemokines in Gestational Diabetes Mellitus

Background

Studies investigating chemokines in gestational diabetes mellitus (GDM) have yielded mixed results. The purpose of this meta-analysis was to explore whether concentrations of chemokines in patients with GDM differed from that of the controls.

Methods

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we systematically searched Web of Science, Embase, Cochrane Library, and PubMed databases for articles, published in any language, on chemokines and GDM through August 1st, 2021. The difference in concentrations of chemokines between patients with GDM and controls was determined by a standardized mean difference (SMD) with a 95% confidence interval (CI), calculated in the meta-analysis of the eligible studies using a random-effects model with restricted maximum-likelihood estimator.

Results

Seventeen studies met the inclusion criteria for the meta-analysis. Altogether, they included nine different chemokines comparisons involving 5,158 participants (1,934 GDM patients and 3,224 controls). Results showed a significant increase of these chemokines (CCL2, CXCL1, CXCL8, CXCL9, and CXCL12) in the GDM patients compared with the controls. However, there was a significant decrease of the chemokines, CCL4, CCL11 and CXCL10, in the GDM patients compared with the controls. Moreover, subgroup analysis revealed a potential role of chemokines as biomarkers in relation to laboratory detection (different sample type and assay methods) and clinical characteristics of GDM patients (ethnicity and body mass index).

Conclusion

GDM is associated with several chemokines (CCL2, CCL4, CCL11, CXCL1, CXCL8, CXCL9, CXCL10 and CXCL12). Therefore, consideration of these chemokines as potential targets or biomarkers in the pathophysiology of GDM development is necessary. Notably, the information of subgroup analysis underscores the importance of exploring putative mechanisms underlying this association, in order to develop new individualized clinical and therapeutic strategies.

The clinical significance of CXCL16 in the treatment of advanced non-small cell lung cancer

BACKGROUND

Bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF)-A, has shown efficacy in patients with advanced nonsquamous non-small cell lung cancer (NSCLC). There are no identified or clinically validated biomarkers to determine the efficacy of bevacizumab. In this study, we assessed the adequacy of chemokine (C-X-C motif) ligand 16 (CXCL16) as a biomarker for patients treated with bevacizumab-containing chemotherapy regimen.

METHODS

Patients diagnosed histologically with NSCLC were enrolled. Serial serum CXCL16 levels during treatment were measured by enzyme-linked immunosorbent assay. The relationship between serum CXCL16 levels before and after treatment, progression-free survival, and overall survival were analyzed. CXCL16 and VEGF-A expressions in lung cancer tissue were also evaluated by immunohistochemical tests.

RESULTS

The median serum level of CXCL16 in these patients was 3.4 ng/mL, which was significantly higher than that in age-matched healthy adults (2.2 ng/mL). Immunohistochemistry results showed that CXCL16 was predominantly localized in the tumor stroma, whereas VEGF was expressed in tumor cells. Including bevacizumab with chemotherapy led to lower CXCL16 levels post-chemotherapy, which correlated with better response rates. In addition, evaluation of differences in serum CXCL16 levels before and after the first-line chemotherapy showed that longer overall survival was achieved in patients who showed a larger decrease in serum CXCL16 levels.

CONCLUSIONS

According to our findings, serum CXCL16 level was identified as a potential biomarker for the efficacy of therapy, including anti-VEGF.

KEY POINTS

Significant findings of the study Patients with NSCLC whose serum CXCL16 levels decreased below 0.07 ng/mL after chemotherapy, showed longer overall survival than those without this decrease. Moreover, low CXCL16 levels corresponded to better response rates among patients with advanced NSCLC treated with bevacizumab-containing chemotherapy. What this study adds Previously there were no identifiable predictive biomarkers to determine the efficacy of bevacizumab. Data from our findings identified serum CXCL16 level as a potential biomarker for the efficacy of bevacizumab-containing chemotherapy.

CXC chemokine ligand 16 is increased in gestational diabetes mellitus and preeclampsia and associated with lipoproteins in gestational diabetes mellitus at 5 years follow-up

BACKGROUND

Women with a history of gestational diabetes mellitus and preeclampsia are at increased risk of cardiovascular disease later in life, but the mechanism remains unclear. The aim of the study was to evaluate the association between CXC chemokine ligand 16 and indices of glucose metabolism, dyslipidemia and systemic inflammation in gestational diabetes mellitus and preeclampsia.

METHODS

This sub-study of the population-based prospective cohort included 310 women. Oral glucose tolerance test was performed during pregnancy and 5 years later along with lipid analysis. CXC chemokine ligand 16 was measured in plasma (protein) and peripheral blood mononuclear cells (messenger RNA) during pregnancy and at follow-up.

RESULTS

Circulating CXC chemokine ligand 16 was higher in gestational diabetes mellitus women early in pregnancy and at follow-up, while higher in preeclampsia women late in pregnancy compared to control women. Messenger RNA of CXC chemokine ligand 16 in peripheral blood mononuclear cells were lower in gestational diabetes mellitus and preeclampsia women compared to control women. Increased circulating CXC chemokine ligand 16 level was associated with a higher apolipoprotein B and low-density lipoprotein cholesterol in gestational diabetes mellitus women but not in normal pregnancy at follow-up.

CONCLUSION

Our study shows that women with gestational diabetes mellitus and preeclampsia had a dysregulated CXC chemokine ligand 16 during pregnancy, and in gestational diabetes mellitus, the increase in CXC chemokine ligand 16 early in pregnancy and after 5 years was strongly associated with their lipid profile.

CXCL16 in Vascular Pathology Research: from Macro Effects to microRNAs

Chemokines and their receptors have become significant factors in atherosclerosis research. CXCL16 is a multifunctional agent located on a separate locus to all other known chemokines and binds only to its "unique" receptor named CXCR6. As a scavenger receptor, adhesion molecule, and chemokine, it quickly became an interesting target in atherosclerosis research as all its functions have a role in vascular pathology. The investigation of the role of CXCL16 in atherosclerosis, although shown in in vitro studies, animal knockout models, and CXCL16 gene polymorphisms, haplotypes, and circulating levels, still shows puzzling results. Genetic and epigenetic studies have just scratched the surface of research necessary for a better assessment of the significance and perspective of this marker in plaque development and progression. In this review, we will summarize current knowledge about CXCL16 in atherosclerosis. Additionally, we will point out the importance of bioinformatics tools for the detection of potentially new CXCL16 regulatory networks through microRNA activity. This review aims to provide a better understanding of the underlying mechanisms, define more specific biomarkers, and discover new therapeutic targets.

Transforming growth factor beta 1 induces CXCL16 and leukemia inhibitory factor expression in osteoclasts to modulate migration of osteoblast progenitors

The processes of bone resorption and bone formation are tightly coupled in young adults, which is crucial to maintenance of bone integrity. We have documented that osteoclasts secrete chemotactic agents to recruit osteoblast lineage cells, contributing to coupling. Bone formation subsequent to bone resorption becomes uncoupled with aging, resulting in significant bone loss. During bone resorption, osteoclasts release and activate transforming growth factor beta 1 (TGF-β1) from the bone matrix; thus, elevated bone resorption increases the level of active TGF-β in the local environment during aging. In this study, we examined the influences of TGF-β1 on the ability of osteoclasts to recruit osteoblasts. TGF-β1 increased osteoclast expression of the chemokine CXCL16 to promote osteoblast migration. TGF-β1 also directly stimulated osteoblast migration; however, this direct response was blocked by conditioned medium from TGF-β1-treated osteoclasts due to the presence of leukemia inhibitory factor (LIF) in the medium. CXCL16 and LIF expression was dependent on TGF-β1 activation of Smad2 and Smad3. These results establish that TGF-β1 induces CXCL16 and LIF production in osteoclasts, which modulate recruitment of osteoblasts to restore the bone lost during the resorptive phase of bone turnover.

Function modification of SR-PSOX by point mutations of basic amino acids

Background

Atherosclerosis (AS) is a common cardiovascular disease. Transformation of macrophages to form foam cells by internalizing modified low density-lipoprotein (LDL) via scavenger receptor (SR) is a key pathogenic process in the onset of AS. It has been demonstrated that SR-PSOX functions as either a scavenger receptor for uptake of atherogenic lipoproteins and bacteria or a membrane-anchored chemokine for adhesion of macrophages and T-cells to the endothelium. Therefore, SR-PSOX plays an important role in the development of AS. In this study the key basic amino acids in the chemokine domain of SR-PSOX have been identified for its functions.

Results

A cell model to study the functions of SR-PSOX was successfully established. Based on the cell model, a series of mutants of human SR-PSOX were constructed by replacing the single basic amino acid residue in the non-conservative region of the chemokine domain (arginine 62, arginine 78, histidine 80, arginine 82, histidine 85, lysine 105, lysine 119, histidine 123) with alanine (designated as R62A, R78A, H80A, R82A, H85A, K105A, K119A and H123A, respectively). Functional studies showed that the mutants with H80A, H85A, and K105A significantly increased the activities of oxLDL uptake and bacterial phagocytosis compared with the wild-type SR-PSOX. In addition, we have also found that mutagenesis of either of those amino acids strongly reduced the adhesive activity of SR-PSOX by using a highly non-overlapping set of basic amino acid residues.

Conclusion

Our study demonstrates that basic amino acid residues in the non-conservative region of the chemokine domain of SR-PSOX are critical for its functions. Mutation of H80, H85, and K105 is responsible for increasing SR-PSOX binding with oxLDL and bacteria. All the basic amino acids in this region are important in the cells adhesion via SR-PSOX. These findings suggest that mutagenesis of the basic amino acids in the chemokine domain of SR-PSOX may contribute to atherogenesis.

Chemokine CXC Ligand 16 serum concentration but not A181V genotype is associated with atherosclerotic stroke

BACKGROUND

Serum chemokine CXC Ligand 16 (CXCL16) concentration is associated with atherosclerosis and CXCL16 expression may be influenced by the polymorphism, A181V. We established whether serum CXCL16 concentration or the A181V genotype is more strongly associated with atherosclerotic stroke and its associated risk factor, carotid atherosclerosis.

METHODS

PCR-RFLP was used to genotype 244 atherosclerotic stroke patients (AS group), 153 stroke-free controls (patient controls) and 167 healthy controls. Serum CXCL16 concentration was determined for a subset of patients (n=135) and all controls. The same subset of patients was then examined using ultrasound to evaluate their carotid atherosclerotic lesions, including intima-media thickness (IMT), plaque stability and carotid plaque area (CPA).

RESULTS

Compared with the patient controls and healthy controls, serum CXCL16 concentration was significantly increased in the AS group (P<0.05, and 0.01). It was also strongly associated with increased IMT, vulnerable plaque and increased CPA (P<0.05, <0.001, and <0.01). However, the CXCL16 A181V genotype distribution and allele frequencies showed no differences between AS and control groups, nor did it influence serum CXCL16 concentration.

CONCLUSION

Serum CXCL16 concentration is significantly associated with atherosclerotic stroke and carotid atherosclerosis, suggesting that this biochemical test may be useful to identify patients at increased risk of atherosclerosis.

Increased serum CXCL16 level is a marker for acute coronary syndromes

BACKGROUND

CXCL16 is a transmembrane molecule combining scavenger receptor functions with the properties of an inflammatory chemokine. Accumulating evidence suggests that CXCL16 is involved in atherosclerosis; however, the role of circulating soluble CXCL16 in human coronary artery disease remains unclear.

METHODS

ELISA was used to examine the concentration of serum-soluble CXCL16 in 26 stable angina pectoris patients (SAP), 29 acute coronary syndrome (ACS) patients and 21 control patients.

RESULTS

In patients with ACS, serum level of CXCL16 was significantly increased compared to control and SAP patients (p <0.001 vs. control; p = 0.041 vs. SAP patients); serum levels of CXCL16 in patients with SAP were higher than in control patients although no statistical significance was found (p = 0.059). No significant association was found between serum CXCL16 and acute-phase reactants, TNF-alpha, or serum lipid parameters. In ACS patients, increased level of serum CXCL16 was not linked to either the severity of coronary stenosis or TIMI risk score, which is an early risk evaluation system for ACS.

CONCLUSIONS

Increased level of serum-soluble CXCL16 was independently associated with ACS.

CXCL16/SR-PSOX--a friend or a foe in atherosclerosis?

Chemokines, scavenger receptors and adhesion molecules have long been known as important players in the pathogenesis of atherosclerosis. A series of studies conducted in the past few years described CXCL16/SR-PSOX--a new molecule combining those three functions, and suggested that CXCL16/SR-PSOX can be a potential player in atherogenesis. Initial ex vivo studies showed that CXCL16/SR-PSOX is abundant in human and murine atherosclerotic lesions. Following in vitro studies suggested that as an adhesion molecule CXCL16/SR-PSOX might mediate T-cell adhesion to the endothelium, as a chemokine - drive T-cell migration, stimulate cell proliferation and elicit inflammatory phenotype in smooth muscle cells (SMC) and, finally, as a scavenger receptor - mediate uptake of atherogenic lipoproteins by macrophages and SMC. All these effects are known to be pro-atherogenic. Surprisingly, in vivo studies performed in murine models of atherosclerosis suggested that CXCL16/SR-PSOX is atheroprotective, while its receptor CXCR6 is harmful. In addition, studies investigating the association of circulating CXCL16/SR-PSOX plasma concentrations with the presence and extent of coronary artery disease (CAD) in humans are controversial suggesting both positive, negative and no association. To finally answer the question whether CXCL16/SR-PSOX can serve as a causative factor, biomarker or even a therapeutic target in atherosclerosis, we are currently in need of carefully designed animal and human studies investigating the effects of CXCL16/SR-PSOX and CXCR6 deficiency, inhibition and over-expression on the progression of atherosclerosis. Such complex approach will help us unravel the mystery of CXCL16/SR-PSOX in atherosclerosis and hopefully develop better ways of treating atherosclerosis by targeting this interesting molecule.