Association of circulating fractalkine (CX3CL1) and CX3CR1(+)CD4(+) T cells with common carotid artery intima-media thickness in patients with chronic kidney disease

Unlocking the potential of Tregs: innovations in CAR technology

Regulatory T cells (Tregs) adoptive immunotherapy is emerging as a viable treatment option for both autoimmune and alloimmune diseases. However, numerous challenges remain, including limitations related to cell number, availability of target-specific cells, stability, purity, homing ability, and safety concerns. To address these challenges, cell engineering strategies have emerged as promising solutions. Indeed, it has become feasible to increase Treg numbers or enhance their stability through Foxp3 overexpression, post-translational modifications, or demethylation of the Treg-specific demethylated region (TSDR). Specificity can be engineered by the addition of chimeric antigen receptors (CARs), with new techniques designed to fine-tune specificity (tandem chimeric antigen receptors, universal chimeric antigen receptors, synNotch chimeric antigen receptors). The introduction of B-cell targeting antibody receptor (BAR) Tregs has paved the way for effective regulation of B cells and plasma cells. In addition, other constructs have emerged to enhance Tregs activation and function, such as optimized chimeric antigen receptors constructs and the use of armour proteins. Chimeric antigen receptor expression can also be better regulated to limit tonic signaling. Furthermore, various opportunities exist for enhancing the homing capabilities of CAR-Tregs to improve therapy outcomes. Many of these genetic modifications have already been explored for conventional CAR-T therapy but need to be further considered for CAR-Tregs therapies. This review highlights innovative CAR-engineering strategies that have the potential to precisely and efficiently manage immune responses in autoimmune diseases and improve transplant outcomes. As these strategies are further explored and optimized, CAR-Treg therapies may emerge as powerful tools for immune intervention.

Markers of terminally differentiated T-cells as predictors of vascular health in renal transplant recipients and healthy adults

Meta-analyses confirm a link between persistent human cytomegalovirus (HCMV) infections and cardiovascular disease, but the mechanisms are unclear. We assess whether proportions of T-cell populations are reliable predictors of subclinical atherosclerosis and/or reflect the burden of HCMV in healthy adults and renal transplant recipients (RTR). Samples were collected from healthy adults and RTR at baseline (T0) and after 32 (24-40) months (T1). Left carotid intima media thickness (cIMT) and proportions of T-cells expressing CD57, LIR-1 or the TEMRA phenotype increased in healthy adults and RTR. The T-cell populations correlated with levels of HCMV-reactive antibodies. Proportions of CD57+, LIR-1+ and TEMRA CD8+ T-cells correlated with left and right cIMT in healthy adults. Proportions of CD57+ and LIR-1+ CD8+ T-cells at T0 predicted left cIMT at T1 among healthy adults, but these associations disappeared after adjustment for covariates. We link LIR-1+ and CD57+CD8+ T-cells with the progression of cIMT in healthy adults.

Indoxyl sulfate in atherosclerosis

Atherosclerosis (AS), a chronic vascular inflammatory disease, has become a main focus of attention worldwide for its chronic progressing disease course and serious complications in the later period. Nevertheless, explanations for the exact molecular mechanisms of AS initiation and development remain to be an unsolved problem. The classic pathogenesis theories, such as lipid percolation and deposition, endothelium injury, inflammation and immune damage, provide the foundation for discovering the new key molecules or signaling mechanisms. Recently, indoxyl sulfate (IS), one of non-free uremia toxins, has been noticeable for its multiple atherogenic effects. IS exists at high concentration in plasma for its great albumin binding rate. Patients with uremia have markedly elevated serum levels of IS due both to the deterioration of renal function and to the high binding affinity of IS to albumin. Nowadays, elevated incidence of circulatory disease among patients with renal dysfunction indicates correlation of uremic toxins with cardiovascular damage. In this review, the atherogenic effects of IS and the underlying mechanisms are summarized with emphasis on several key pathological events associated with AS developments, such as vascular endothelium dysfunction, arterial medial lesions, vascular oxidative stress, excessive inflammatory responses, calcification, thrombosis and foam cell formation. Although recent studies have proved the great correlation between IS and AS, deciphering cellular and pathophysiological signaling by confirming key factors involved in IS-mediated atherosclerosis development may enable identification of novel therapeutic targets.

Identification of a novel immune landscape signature as effective diagnostic markers related to immune cell infiltration in diabetic nephropathy

Background

The study aimed to identify core biomarkers related to diagnosis and immune microenvironment regulation and explore the immune molecular mechanism of diabetic nephropathy (DN) through bioinformatics analysis.

Methods

GSE30529, GSE99325, and GSE104954 were merged with removing batch effects, and different expression genes (DEGs) were screened at a criterion |log2FC| >0.5 and adjusted P <0.05. KEGG, GO, and GSEA analyses were performed. Hub genes were screened by conducting PPI networks and calculating node genes using five algorithms with CytoHubba, followed by LASSO and ROC analysis to accurately identify diagnostic biomarkers. In addition, two different GEO datasets, GSE175759 and GSE47184, and an experiment cohort with 30 controls and 40 DN patients detected by IHC, were used to validate the biomarkers. Moreover, ssGSEA was performed to analyze the immune microenvironment in DN. Wilcoxon test and LASSO regression were used to determine the core immune signatures. The correlation between biomarkers and crucial immune signatures was calculated by Spearman analysis. Finally, cMap was used to explore potential drugs treating renal tubule injury in DN patients.

Results

A total of 509 DEGs, including 338 upregulated and 171 downregulated genes, were screened out. "chemokine signaling pathway" and "cell adhesion molecules" were enriched in both GSEA and KEGG analysis. CCR2, CX3CR1, and SELP, especially for the combination model of the three genes, were identified as core biomarkers with high diagnostic capabilities with striking AUC, sensitivity, and specificity in both merged and validated datasets and IHC validation. Immune infiltration analysis showed a notable infiltration advantage for APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. In addition, the correlation analysis showed that CCR2, CX3CR1, and SELP were strongly and positively correlated with checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. Finally, dilazep was screened out as an underlying compound for DN analyzed by CMap.

Conclusions

CCR2, CX3CR1, and SELP are underlying diagnostic biomarkers for DN, especially in their combination. APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation may participate in the occurrence and development of DN. At last, dilazep may be a promising drug for treating DN.

T cells and their products in diabetic kidney disease

Diabetic kidney disease (DKD) is the most common cause of end-stage renal disease and has gradually become a public health problem worldwide. DKD is increasingly recognized as a comprehensive inflammatory disease that is largely regulated by T cells. Given the pivotal role of T cells and T cells-producing cytokines in DKD, we summarized recent advances concerning T cells in the progression of type 2 diabetic nephropathy and provided a novel perspective of immune-related factors in diabetes. Specific emphasis is placed on the classification of T cells, process of T cell recruitment, function of T cells in the development of diabetic kidney damage, and potential treatments and therapeutic strategies involving T cells.

Role of the CX3CL1-CX3CR1 axis in renal disease

Excessive infiltration of immune cells into the kidney is a key feature of acute and chronic kidney diseases. The family of chemokines comprises key drivers of this process. Fractalkine [chemokine (C-X3-C motif) ligand 1 (CX3CL1)] is one of two unique chemokines synthesized as a transmembrane protein that undergoes proteolytic cleavage to generate a soluble species. Through interacting with its cognate receptor, chemokine (C-X3-C motif) receptor 1 (CX3CR1), CX3CL1 was originally shown to act as a conventional chemoattractant in the soluble form and as an adhesion molecule in the transmembrane form. Since then, other functions of CX3CL1 beyond leukocyte recruitment have been described, including cell survival, immunosurveillance, and cell-mediated cytotoxicity. This review summarizes diverse roles of CX3CL1 in kidney disease and potential uses as a therapeutic target and novel biomarker. As the CX3CL1-CX3CR1 axis has been shown to contribute to both detrimental and protective effects in various kidney diseases, a thorough understanding of how the expression and function of CX3CL1 are regulated is needed to unlock its therapeutic potential.

Fractalkine (CX3CL1) and Its Receptor CX3CR1: A Promising Therapeutic Target in Chronic Kidney Disease?

Innate immune cells are key contributors to kidney inflammation and fibrosis. Infiltration of the renal parenchyma by innate immune cells is governed by multiple signalling pathways. Since the discovery of the chemokine fractalkine (CX3CL1) and its receptor, CX3CR1 over twenty years ago, a wealth of evidence has emerged linking CX3CL1-CX3CR1 signalling to renal pathologies in both acute and chronic kidney diseases (CKD). However, despite the extent of data indicating a pathogenic role for this pathway in kidney disease and its complications, no human trials of targeted therapeutic agents have been reported. Although acute autoimmune kidney disease is often successfully treated with immunomodulatory medications, there is a notable lack of treatment options for patients with progressive fibrotic CKD. In this article we revisit the CX3CL1-CX3CR1 axis and its functional roles. Furthermore we review the accumulating evidence that CX3CL1-CX3CR1 interactions mediate important events in the intra-renal pathophysiology of CKD progression, particularly via recruitment of innate immune cells into the kidney. We also consider the role that systemic activation of the CX3CL1-CX3CR1 axis in renal disease contributes to CKD-associated cardiovascular disease. Based on this evidence, we highlight the potential for therapies targeting CX3CL1 or CX3CR1 to benefit people living with CKD.

CX3CR1 at V249M and T280M Gene Polymorphism and Its Potential Risk for End-Stage Renal Diseases in Egyptian Patients

CX3CL1-CX3CR1 pathway may be one of the future treatment targets to delay the progression of end-stage renal diseases. This study aimed to evaluate the CX3CR gene polymorphism in Egyptian patients with ESRD and its relation to fractalkine blood level. The study included 100 patients with ESRD on dialysis, 61 males and 39 females with mean age 51.02 ± 7.8 years. The V2491 genotype revealed a significant increase in the frequency of GG genotype in healthy control (83%) compared to patients [69%] with a significant increase in GA in patients [30%] compared to control subjects [15%], P = 0.03. T280M study showed a statistically significant prevalence of TT genotype in healthy control subjects [86%-OR 95% CI 1.7] compared to patients [70%] with a significant increase in the prevalence of TA in patients [29%] compared to control subjects [13%], P = 0.01. There was a significant increase in fractalkine levels in genotypes GA + AA [503.04±224.1] pg/ml compared to genotype GG [423.6 210.3], P = 0.03. Moreover, there was a significant increase in the blood level of fractalkine in genotype TA + AA [498.8 219.6] compared to genotype TT [426.8±212.8], P = 0.05. In conclusion, our study showed that both V2491-GA genotype and T280M-TA are associated with potential risk for end-stage renal disease in Egyptian patients.

The Role of Chemokines and Chemokine Receptors in Diabetic Nephropathy

Kidney function decline is one of the complications of diabetes mellitus and may be indicated as diabetic nephropathy (DN). DN is a chronic inflammatory disease featuring proteinuria and a decreasing glomerular filtration rate. Despite several therapeutic options being currently available, DN is still the major cause of end-stage renal disease. Accordingly, widespread innovation is needed to improve outcomes in patients with DN. Chemokines and their receptors are critically involved in the inflammatory progression in the development of DN. Although recent studies have shown multiple pathways related to the chemokine system, the specific and direct effects of chemokines and their receptors remain unclear. In this review, we provide an overview of the potential role and mechanism of chemokine systems in DN proposed in recent years. Chemokine system-related mechanisms may provide potential therapeutic targets in DN.

The Impact of Uremic Toxicity Induced Inflammatory Response on the Cardiovascular Burden in Chronic Kidney Disease

Uremic toxin (UT) retention in chronic kidney disease (CKD) affects biological systems. We aimed to identify the associations between UT, inflammatory biomarkers and biomarkers of the uremic cardiovascular response (BUCVR) and their impact on cardiovascular status as well as their roles as predictors of outcome in CKD patients. CKD patients stages 3, 4 and 5 (n = 67) were recruited and UT (indoxyl sulfate/IS, p-cresil sulfate/pCS and indole-3-acetic acid/IAA); inflammatory biomarkers [Interleukin-6 (IL-6), high sensitivity C reactive protein (hsCRP), monocyte chemoattractant protein-1 (MCP-1), soluble vascular adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble Fas (sFas)] and BUCVRs [soluble CD36 (sCD36), soluble receptor for advanced glycation end products (sRAGE), fractalkine] was measured. Patients were followed for 5.2 years and all causes of death was used as the primary outcome. Artery segments collected at the moment of transplantation were used for the immunohistochemistry analysis in a separate cohort. Estimated glomerular filtration rate (eGFR), circulating UT, plasma biomarkers of systemic and vascular inflammation and BUCVR were strongly interrelated. Patients with plaque presented higher signs of UT-induced inflammation and arteries from CKD patients presented higher fractalkine receptor (CX3CR1) tissue expression. Circulating IS (p = 0.03), pCS (p = 0.007), IL-6 (p = 0.026), sFas (p = 0.001), sCD36 (p = 0.01) and fractalkine (p = 0.02) were independent predictors of total mortality risk in CKD patients. Our results reinforce the important role of uremic toxicity in the pathogenesis of cardiovascular disease (CVD) in CKD patients through an inflammatory pathway.

Extracellular vesicles as immune mediators in response to kidney injury

Important progress has been made on cytokine signaling in response to kidney injury in the past decade, especially cytokine signaling mediated by extracellular vesicles (EVs). For example, EVs released by injured renal tubular epithelial cells (TECs) can regulate intercellular communications and influence tissue recovery via both regulating the expression and transferring cytokines, growth factors, as well as other bioactive molecules at the site of injury. The effects of EVs on kidney tissue seem to vary depending on the sources of EVs; however, the literature data are often inconsistent. For example, in rodents EVs derived from mesenchymal stem cells (MSC-EVs) and endothelial progenitor cells (EPC-EVs) can have both beneficial and harmful effects on injured renal tissue. Caution is thus needed in the interpretation of these data as contradictory findings on EVs may not only be related to the origin of EVs, they can also be caused by the different methods used for EV isolation and the physiological and pathological states of the tissues/cells under which they were obtained. Here, we review and discuss our current understanding related to the immunomodulatory function of EVs in renal tubular repair in the hope of encouraging further investigations on mechanisms related to their antiinflammatory and reparative role to better define the therapeutic potential of EVs in renal diseases.

CX3CL1/CX3CR1 Axis, as the Therapeutic Potential in Renal Diseases: Friend or Foe?

The fractalkine receptor chemokine (C-X3-C motif) receptor 1 (CX3CR1) and its highly selective ligand CX3CL1 mediate chemotaxis and adhesion of immune cells, which are involved in the pathogenesis and progression of numerous inflammatory disorders and malignancies. The CX3CL1/CX3CR1 axis has recently drawn attention as a potential therapeutic target because it is involved in the ontogeny, homeostatic migration, or colonization of renal phagocytes. We performed a Medline/PubMed search to detect recently published studies that explored the relationship between the CX3CL1/CX3CR1 axis and renal diseases and disorders, including diabetic nephropathy, renal allograft rejection, infectious renal diseases, IgA nephropathy, fibrotic kidney disease, lupus nephritis and glomerulonephritis, acute kidney injury and renal carcinoma. Most studies demonstrated its role in promoting renal pathopoiesis; however, several recent studies showed that the CX3CL1/CX3CR1 axis could also reduce renal pathopoiesis. Thus, the CX3CL1/CX3CR1 axis is now considered to be a double-edged sword that could provide novel perspectives into the pathogenesis and treatment of renal diseases and disorders.

Association of chemokine receptor CX3CR1 V249I and T280M polymorphisms with chronic kidney disease

The chemokine fractalkine (CX3CL1) and its receptor CX3CR1 are involved in the activation of leukocytes. Two common single-nucleotide polymorphisms of the CX3CR1 gene, V249I and T280M, have been associated with reduced fractalkine signaling, leading to decreased adhesive function and leukocyte chemotaxis. We hypothesized that variation in the CX3CR1 gene could be associated with chronic kidney disease (CKD), a disease of inflammatory activation. We studied the association between CX3CR1 V249I and T280M polymorphisms, and fractalkine and highly sensitive C-reactive protein (hs-CRP) levels in 123 patients with CKD and 100 healthy controls (HCs). Genotype analysis was done by polymerase chain reaction-restriction fragment length polymorphism, and fractalkine and hs-CRP levels were analyzed by enzyme-linked immunosorbent assay. MM genotype of T280M was absent in CKD patients, while in controls it was seen in 1% of the individuals. The allele frequencies in both the groups were similar (P = 0.059). Compared to HC, M280M + T280M genotype was more frequent in CKD (P = 0.041). The frequency of II genotype of V249I was 0.8% in CKD, whereas in HC, it was 2%. I249I + V249I genotype was more frequent in CKD as compared to HC (P = 0.034). No difference in allelic frequency of V249I was noted between the two groups (P = 0.061, odds ratios = 1.74, 95% confidence intervals = 0.96–3.12). Plasma fractalkine and serum hs-CRP levels were higher in CKD subjects (P = 0.004 and P < 0.0001). No association of either genotype was found with fractalkine and hs-CRP levels. Polymorphisms at I249 and M280 genotype in CX3CR1 gene are associated with CKD; however, there was no association of fractalkine or inflammatory marker with these genotypes.

T Cell CX3CR1 Mediates Excess Atherosclerotic Inflammation in Renal Impairment

Reduced kidney function increases the risk for atherosclerosis and cardiovascular death. Leukocytes in the arterial wall contribute to atherosclerotic plaque formation. We investigated the role of fractalkine receptor CX3CR1 in atherosclerotic inflammation in renal impairment. Apoe(-/-) (apolipoprotein E) CX3CR1(-/-) mice with renal impairment were protected from increased aortic atherosclerotic lesion size and macrophage accumulation. Deficiency of CX3CR1 in bone marrow, only, attenuated atherosclerosis in renal impairment in an independent atherosclerosis model of LDL receptor-deficient (LDLr(-/-)) mice as well. Analysis of inflammatory leukocytes in atherosclerotic mixed bone-marrow chimeric mice (50% wild-type/50% CX3CR1(-/-) bone marrow into LDLr(-/-) mice) showed that CX3CR1 cell intrinsically promoted aortic T cell accumulation much more than CD11b(+)CD11c(+) myeloid cell accumulation and increased IL-17-producing T cell counts. In vitro, fewer TH17 cells were obtained from CX3CR1(-/-) splenocytes than from wild-type splenocytes after polarization with IL-6, IL-23, and TGFβ Polarization of TH17 or TREG cells, or stimulation of splenocytes with TGFβ alone, increased T cell CX3CR1 reporter gene expression. Furthermore, TGFβ induced CX3CR1 mRNA expression in wild-type cells in a dose- and time-dependent manner. In atherosclerotic LDLr(-/-) mice, CX3CR1(+/-) T cells upregulated CX3CR1 and IL-17A production in renal impairment, whereas CX3CR1(-/-) T cells did not. Transfer of CX3CR1(+/-) but not Il17a(-/-) T cells into LDLr(-/-)CX3CR1(-/-) mice increased aortic lesion size and aortic CD11b(+)CD11c(+) myeloid cell accumulation in renal impairment. In summary, T cell CX3CR1 expression can be induced by TGFβ and is instrumental in enhanced atherosclerosis in renal impairment.

Associations of fractalkine receptor (CX3CR1) and CCR5 gene variants with hypertension, diabetes and atherosclerosis in chronic renal failure patients undergoing hemodialysis

PURPOSE

We aimed to investigate the associations of fractalkine receptor (CX3CR1) V249I, T280M and CCR5-59029 A/G gene polymorphisms in chronic renal failure (CRF) subjects undergoing hemodialysis and to evaluate possible associations of these polymorphisms with hypertension (HT), diabetes mellitus (DM) and atherosclerosis (AS).

METHODS

A total of 225 CRF subjects undergoing hemodialysis and 201 healthy controls were enrolled in the study. CRF subjects were divided into three major subgroups according to comorbidities including HT (n = 127), DM (n = 65) and AS (n = 33). Genotyping was done using polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The II genotype and I allele frequencies of CX3CR1 V249I polymorphism were found significantly more frequent in CRF subjects, CRF subjects with DM and CRF subjects with AS compared with controls (p < 0.05 for all comparisons). G allele frequency of CCR5 polymorphism was found significantly more prevalent in CRF subjects with DM than that of controls. Further, GG genotype and G allele frequencies of CCR5 polymorphism were significantly more prevalent in CRF subjects with AS compared with controls (p < 0.05). We also explored these polymorphisms among CRF subjects with and without following comorbidities: HT, DM, AS. We found significant association between CRF subjects with HT and without HT in terms of genotype and allele frequencies of V249I polymorphism (p < 0.05). CX3CR1 T280M polymorphism was not found significantly different in none of the comparisons.

CONCLUSION

These data demonstrate possible associations between CX3CR1 V249I and CCR5-59029 A/G polymorphisms and/or HT, DM and AS in CRF subjects.

Chemokine CX3CL1 and its receptor CX3CR1 are associated with human atherosclerotic lesion volnerability

BACKGROUND

CX3CL1 and its receptor CX3CR1 have been emphasized in atherosclerosis recently. In this study we investigated the role of the chemokines CX3CL1 and their receptor CX3CR1 in atherogenesis and identified whether the genetic variations in CX3CL1 and CX3CR1 impacted the atherosclerosis process in coronary artery disease (CAD) or not.

METHODS

CX3CL1/CX3CR1 expression in coronary and carotid artery specimens were analysed by immunohistochemistry. CX3CR1 expression on CD4(+) CD28(-) T cells was analysed by flow cytometry. We also screened for CX3CL1/CX3CR1 sequence variations selected from the hapmap database and examined the association between CX3CL1/CX3CR1 and CAD in the Chinese Han population.

RESULTS

Immunohistochemical staining of tissue from CAD patients showed increased CX3CL1/CX3CR1 expression in atherosclerotic coronary and carotid artery plaques compared with normal arteries. CX3CL1/CX3CR1 expression was correlated with the severity of the atherosclerosis lesion. Patients with CAD also showed an increased number of CX3CR1(+) CD4(+) CD28(-) T cells. Compared with their corresponding wild-type genotypes, CX3CL1 rs170364 and CX3CR1 rs17793056 were associated with increased susceptibility to CAD.

CONCLUSIONS

CX3CL1 and CX3CR1 may contribute to the formation of coronary atherosclerotic plaque in CAD.CX3CL1 rs170364 and CX3CR1 rs17793056 polymorphisms may be independent genetic risk factors for CAD.

Serum Fractalkine (CX3CL1) and Cardiovascular Outcomes and Diabetes: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study

BACKGROUND

Cardiometabolic disease is a major cause of morbidity and mortality in persons with chronic kidney disease (CKD). Fractalkine (CX3CL1) is a potential mediator of both atherosclerosis and metabolic disease. Studies of the relationship of CX3CL1 with risk of cardiovascular disease (CVD) events and metabolic traits are lacking, particularly in the high-risk setting of CKD.

STUDY DESIGN

Cross-sectional and longitudinal observational analysis.

SETTING & PARTICIPANTS

Adults with CKD from 7 US sites participating in the Chronic Renal Insufficiency Cohort (CRIC) Study.

PREDICTOR

Quartiles of plasma CX3CL1 levels at baseline.

OUTCOMES

Baseline estimated glomerular filtration rate from a creatinine and cystatin C-based equation, prevalent and incident CVD, diabetes, metabolic syndrome and its criteria, homeostatic model assessment of insulin resistance, hemoglobin A1c level, myocardial infarction, all-cause mortality, and the composite outcome of myocardial infarction/all-cause mortality.

RESULTS

Among 3,687 participants, baseline CX3CL1 levels were associated positively with several CVD risk factors and metabolic traits, lower estimated glomerular filtration rate, and higher levels of inflammatory cytokines, as well as prevalent CVD (OR, 1.09; 95% CI, 1.01-1.19; P=0.03). Higher CX3CL1 level also was associated with prevalent diabetes (OR, 1.26; 95% CI, 1.16-1.38; P<0.001) in adjusted models. During a mean follow-up of 6 years, there were 352 deaths, 176 myocardial infarctions, and 484 composite outcomes. In fully adjusted models, 1-SD higher CX3CL1 level increased the hazard for all-cause mortality (1.11; 95% CI, 1.00-1.22; P=0.02) and the composite outcome (1.09; 95% CI, 1.00-1.19; P=0.04).

LIMITATIONS

Study design did not allow evaluation of changes over time, correlation with progression of phenotypes, or determination of causality of effect.

CONCLUSIONS

Circulating CX3CL1 level may contribute to both atherosclerotic CVD and diabetes in a CKD cohort. Further studies are required to establish mechanisms through which CX3CL1 affects the pathogenesis of atherosclerosis and diabetes.

Serum levels of fractalkine are associated with markers of insulin resistance in gestational diabetes

AIMS

Fractalkine has recently been introduced as an adipokine that improves glucose tolerance. Regulation of fractalkine in gestational diabetes, as well as its association with markers of obesity, glucose and lipid metabolism, inflammation and renal function, has not been elucidated.

METHODS

Circulating fractalkine was quantified by enzyme-linked immunosorbent assay in 74 women with gestational diabetes and 74 healthy, pregnant control subjects matched for age, BMI, and gestational age.

RESULTS

Median (interquartile range) levels of fractalkine were not significantly different between the two groups [gestational diabetes: 2.24 (2.16) μg/l; control: 2.45 (1.38) μg/l] (P = 0.461). In multivariate linear regression analysis, fractalkine remained independently associated with homeostasis model assessment of insulin resistance (β = -0.253, P = 0.002) and the proinflammatory adipokine progranulin (β = 0.218, P = 0.007).

CONCLUSIONS

Circulating fractalkine is not different between women with gestational diabetes and control subjects, but the adipokine is independently associated with markers of insulin resistance and proinflammatory progranulin in pregnancy.

Decreased CD127 expression on CD4+ T-cells and elevated frequencies of CD4+CD25+CD127- T-cells in children with long-lasting type 1 diabetes

Pathobiology of type 1 diabetes (T1D) is predominantly associated with T-cell-related actions. Homeostasis of majority of T-cells is critically dependent on signals mediated by CD127 (interleukin-7 receptor, IL-7R). In contrast, regulatory T-cells express very little CD127 and thereby may be delineated by CD4+CD25+CD127− phenotype. Here we aimed to analyze CD127 expression on CD4+ and CD8+ T-cells and enumerate CD4+CD25+CD127− T-cells in long-lasting T1D. T-cells were analyzed by flow cytometry and immunologic data were correlated with vascular, metabolic, and inflammatory parameters. We demonstrated significantly decreased CD127 levels on CD4+, but not CD8+, T cells in T1D pediatric patients. Interestingly, frequencies of CD4+CD25+CD127− T-cells were significantly enhanced in T1D children and correlated well with frequencies of CD34+CD144+ endothelial progenitor cells and CD4+CD25− T-cells. Levels of CD127 on both CD4+ and CD8+ T-cells in T1D patients were not correlated to each other or HbA_1C. Interestingly, however, CD127 levels on CD4+ T-cells were significantly correlated to frequencies of CD4+CD25+CD127− T-cells, whereas CD127 levels on CD8+ T-cells were significantly correlated to concentrations of VEGF and triglycerides. Our data indicate that CD127 expression is differentially modulated on CD4+ and CD8+ T-cells in the course of T1D. Moreover, we demonstrated that, in contrast to recent-onset T1D, long-lasting T1D is associated with enhancement of T-cells with regulatory phenotype.

Heat shock proteins 60 and 70 specific proinflammatory and cytotoxic response of CD4+CD28null cells in chronic kidney disease

Background. CD4⁺CD28^null T cells are expanded in peripheral blood of patients with chronic kidney disease and associated with subclinical atherosclerosis. However, triggers for the oligoclonal expansion and activation of these cells are not clear. Methods. We investigated twenty-five stage V-IV chronic kidney disease (CKD) patients and eight healthy subjects (HC). Peripheral mononuclear cells were isolated and incubated with heat shock protein- (HSP) 60 and 70. CD4⁺CD28^null and CD4⁺CD28⁺ cells were sorted by flowcytometry and antigen specific response was assessed by the mRNA and protein expression of interferon (IFN)-γ, perforin, and granzyme B using qRT-PCR and Elispot. Results. The basal mRNA expression of IFN-γ, perforin, and granzyme B in CD4⁺CD28^null cells was higher in subjects with CKD compared to that in HC (P < 0.0001). Subjects with CKD also showed expression of IFN-γ, perforin, and granzyme B in the CD4⁺CD28⁺ subset, but this was much weaker than that seen in the CD4⁺CD28^null population (P < 0.0001). We did not note the expression of these molecules at mRNA or protein level in either subset of CD4 cells in HC. After incubation with HSP60 and HSP70, CD4⁺CD28^null cells showed increased expression at mRNA (P < 0.001) and protein level (P < 0.001). CD4⁺CD28⁺ cells also showed a weak increase in expression. No antigen-specific response was noted in HC. Conclusion. These data show that CD4⁺CD28^null cells in subjects with CKD react with HSP60 and HSP70 by upregulating the expression of IFN-γ, perforin and granzyme B. Increased circulating level of HSP60 and HSP70 might play a role in initiation and/or progression of atherosclerosis in CKD subjects through perturbation of CD4⁺CD28^null cells.

Chemokines and atherosclerosis: focus on the CX3CL1/CX3CR1 pathway

Atherosclerosis is currently considered an inflammatory disease. Much attention has been focused on the potential role of inflammatory mediators as prognostic/diagnostic markers or therapeutic targets of atherosclerotic cardiovascular disease. CX3CL1 (or fractalkine) is a structurally and functionally unique chemokine with a well documented role in atherosclerosis. In its membrane bound form it promotes the firm adhesion of rolling leucocytes onto the vessel wall, while in its soluble form it serves as a potent chemoattractant for CX3CR1-expressing cells. Additionally, CX3CL1 exerts cytotoxic effects on the endothelium as well as anti-apoptotic and proliferative effects on vascular cells, affecting the context and stability of the atherosclerotic plaque. Studies on animal models have shown that the blockade of the CX3CL1/CX3CR1 pathway ameliorates the severity of atherosclerosis, while genetic epidemiology has confirmed that a genetically-defined less active CX3CL1/CX3CR1 pathway is associated with a reduced risk of atherosclerotic disease in humans. Although several studies support an important pathogenic role of CX3CL1/CX3CR1 in atherogenesis and plaque destabilization, this does not necessarily suggest that this pathway is a suitable therapeutic target or that CX3CL1 can serve as a prognostic/diagnostic biomarker. Further studies on the CX3CL1/CX3CR1 chemokine pathway are clearly warranted to justify the clinical relevance of its role in atherosclerosis.

Elevated plasma fractalkine levels are associated with higher levels of IL-6, Apo-B, LDL-C and insulin, but not with body composition in a large female twin sample

OBJECTIVE

Plasma fractalkine (FRACT) is involved in the development of numerous inflammatory conditions including atherosclerosis. It is associated with type 2 diabetes mellitus and adipose inflammation. However, whether FRACT is associated with major risk factors for cardiovascular disease, in particular obesity, metabolic syndrome and blood lipids, is virtually unknown.

METHODS

The study included a large community-based sample of 3306 middle-aged women drawn from the general UK population. Blood samples were analyzed for circulating levels of FRACT, leptin, insulin, glucose, LDL-C, HDL-C, Apo-A, ApoB and IL-6. Obesity was assessed by fat body mass (FBM) using dual-energy x-ray absorptiometry and by body mass index (BMI).

RESULTS

We found no association between FRACT and body composition, in particular adiposity. Obese and non obese subjects with metabolic syndrome tended to have higher levels of FRACT compared with non-obese subjects without metabolic syndrome but this did not reach statistical significance. Most importantly we report significant correlations between FRACT and circulating IL-6, Apo-B, LDL-C and insulin. The associations with IL-6 and Apo-B were particularly significant (P-value<0.001), and survived correction for multiple testing and adjustment for age and other covariates.

CONCLUSION

Higher FRACT levels correlated with elevated levels of IL-6, Apo-B, LDL-C and insulin, all known risk factors for several clinical related diseases suggesting a potential role of FRACT in inflammation and tissue injury. Variations of FRACT levels are not influenced by body composition and are not correlated with leptin indicating that fat mass alone is not responsible for elevation of FRACT seen in obese individuals.

Targeting chemokines in proteinuria-induced renal disease

INTRODUCTION

Proteinuria is a common finding in glomerular diseases that contributes to the progression of chronic kidney injury. Tubular cells reabsorb the excess of albumin and other plasma proteins from the tubular lumen, triggering several pathophysiologic responses, such as overexpression of fibrogenic mediators and inflammatory chemokines. Chemokines are implicated both in the recruitment of inflammatory infiltrate and in a number of physiological and pathological processes related to protein overload.

AREAS COVERED

In recent years, the specific chemokines and their receptors and the intracellular signaling pathways involved in proteinuria-induced renal damage have been identified. This review provides an overview of the role of chemokines and their receptors in proteinuria-related renal disease and summarizes novel therapeutic approaches to restrain the progression of renal damage.

EXPERT OPINION

Inhibition of chemokine-induced biological activities is a promising therapeutic strategy in proteinuric disorders. Neutralizing antibodies and small organic molecules targeting chemokines and chemokine receptors have been proven to prevent inflammation and renal damage in experimental models of protein overload. Some of these compounds are currently being tested in human clinical trials.

Association between serum neopterin and inflammatory activation in chronic kidney disease

Background. The serum levels of neopterin, a marker associated with cell-mediated immunity are elevated in chronic kidney disease (CKD). We evaluated serum neopterin levels and investigated its association with markers of inflammation in a cross-section of CKD subjects without known cardiovascular disease. Methods. Serum neopterin levels were measured in 118 patients with stage 3–5 CKD and 41 healthy subjects with normal kidney function (HC). Patients with known cardiovascular disease were excluded. We also estimated highly sensitive CRP (hsCRP) and interluekin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in the CKD subjects. All assays were done using commercially available ELISA kits. The correlation between neopterin and markers of inflammation were investigated. Results. Of the CKD population, 82 were in stage 5 (60 stage 5 D), 24 in stage 4, and 12 in stage 3. The mean age was 51.04 ± 1.3 years and 66% were males. The commonest cause of CKD was diabetes (36%). Serum neopterin levels were 5-fold higher in CKD patients as compared to HC (74.8 ± 3.6 versus 15.0 ± 2.8 nmol/L, P < 0.0001). There was a graded increase of serum neopterin from stages 3 to 4 and 5. CKD 5 D patients exhibited significantly higher levels compared to nondialysis stage 5 patients (P < 0.0001). An inverse correlation was noted between serum neopterin and eGFR (r = −0.359, P < 0.0001). Serum neopterin correlated with hsCRP (r = 0.285, P = 0.002), IL-6 (r = 0.212, P = 0.034), and IFN-γ (r = 0.32, P = 0.001) but not with TNF-α. Conclusion. Serum neopterin level is elevated and correlates with the severity of CKD. The elevation correlates with elevation of most, but not all, inflammatory markers. Its role in future development of cardiovascular disease and modulation with anti-inflammatory therapies needs further studies.

Pathogenic features of CD4+CD28- T cells in immune disorders

Aging of the immune system contributes to the increased morbidity and mortality of the elderly population and may occur prematurely in patients with immune disorders. One of the main characteristics of immunosenescence is the expansion of CD4(+)CD28(-) T cells in the blood. These cells are effector memory T cells with cytotoxic capacity, and have been recently described to have pathogenic potential in a variety of immune disorders. Interestingly, CD4(+)CD28(-) T cells have now been found to infiltrate target tissues of patients with multiple sclerosis, rheumatoid arthritis, myopathies, acute coronary syndromes, and other immune-related diseases. In this review, we discuss potential factors and mechanisms that may induce the expansion of these cells, as well as their putative pathogenic mechanisms in immune disorders.