Associations between Inflammation, Hemoglobin Levels, and Coronary Artery Disease in Non-Albuminuric Subjects with and without Type 2 Diabetes Mellitus

In this cross-sectional study, we evaluated the associations of inflammation and hemoglobin with coronary artery disease (CAD) in subjects with type 2 diabetes mellitus (T2DM) and preserved kidney function. We recruited 638 participants-254 with T2DM-subjected to coronary angiography with no known cardiovascular disease, normal glomerular filtration rates, and without albuminuria. The hemoglobin and serum levels of inflammatory markers, including high-sensitivity C-reactive protein (hs-CRP), were measured. Multivariable analyses showed that inflammatory markers were not related to the severity of the stenosis in the group of subjects with diabetes. Conversely, inflammatory cytokines and albuminuria were directly related to the percentage of stenosis in subjects without T2DM (R2 = 0.038, p < 0.001). Patients with diabetes presented lower hemoglobin levels, particularly in those who also had significant CAD (14.4 [13.6-15.1] vs. 13.6 [12.2-14.8] g/dL, p = 0.03). Similarly, hemoglobin levels and albuminuria were inversely related to the severity of stenosis exclusively in subjects with diabetes, even after adjusting for multiple confounding factors (R2 = 0.081, p < 0.001). We conclude that reductions in hemoglobin levels in subjects with T2DM and normoalbuminuria may constitute a more relevant risk factor for CAD than inflammation.

Association of Klotho with Coronary Artery Disease in Subjects with Type 2 Diabetes Mellitus and Preserved Kidney Function: A Case-Control Study

Circulating Klotho levels are significantly reduced in subjects with type 2 diabetes mellitus (T2DM) and in kidney disease patients. In this work, the relationship between Klotho levels and the coronary artery disease (CAD) burden in subjects with T2DM and preserved kidney function was analyzed. For this, we performed a cross-sectional case-control study involving 133 subjects with T2DM and 200 age-, sex- and CAD-incidence-matched, non-diabetic patients undergoing non-emergency diagnostic coronary angiography. All of them were non-albuminuric and with normal glomerular filtration rates. The concentrations of serum Klotho, fibroblast growth factor 23, and inflammatory markers were also measured. As expected, the serum Klotho concentration was lower in the T2DM group (12.3% lower, p = 0.04). However, within the group of patients with T2DM, those subjects with CAD presented significantly higher Klotho levels than those without significant coronary stenosis (314.5 (6.15-562.81) vs. 458.97 (275.2-667.2) pg/mL; p = 0.02). Multiple regression analysis revealed that serum Klotho was positively related with stenosis values exclusively in subjects with T2DM (adjusted R2 = 0.153, p < 0.01). Moreover, logistic regression analysis showed that Klotho was positively associated with the presence of significant CAD in the group of T2DM patients (OR: 1.001; p = 0.041). Our data suggest that higher levels of circulating Klotho in subjects with T2DM and preserved kidney function are associated with the presence of significant CAD.

Klotho inversely relates with carotid intima- media thickness in atherosclerotic patients with normal renal function (eGFR ≥60 mL/min/1.73m2): a proof-of-concept study

Introduction

Klotho protein is predominantly expressed in the kidneys and has also been detected in vascular tissue and peripheral blood circulating cells to a lesser extent. Carotid artery intima-media thickness (CIMT) burden, a marker of subclinical atherosclerosis, has been associated with reductions in circulating Klotho levels in chronic kidney disease patients, who show reduced levels of this protein at all stages of the disease. However, the contribution of serum Klotho and its expression levels in peripheral blood circulating cells and in the carotid artery wall on the CIMT in the absence of kidney impairment has not yet been evaluated.

Methods

We conducted a single-center study in 35 atherosclerotic patients with preserved kidney function (eGFR≥60 mL/min/1.73m2) subjected to elective carotid surgery. Serum levels of Klotho and cytokines TNFa, IL6 and IL10 were determined by ELISA and transcripts encoding for Klotho (KL), TNF, IL6 and IL10 from vascular segments were measured by qRT-PCR. Klotho protein expression in the intima-media and adventitia areas was analyzed using immunohistochemistry.

Results

APatients with higher values of CIMT showed reduced Klotho levels in serum (430.8 [357.7-592.9] vs. 667.8 [632.5-712.9] pg/mL; p<0.001), mRNA expression in blood circulating cells and carotid artery wall (2.92 [2.06-4.8] vs. 3.69 [2.42-7.13] log.a.u., p=0.015; 0.41 [0.16-0.59] vs. 0.79 [0.37-1.4] log.a.u., p=0.013, respectively) and immunoreactivity in the intimal-medial area of the carotids (4.23 [4.15-4.27] vs. 4.49 [4.28-4.63] log µm2 p=0.008). CIMT was inversely related with Klotho levels in serum (r= -0.717, p<0.001), blood mRNA expression (r=-0.426, p=0.011), and with carotid artery mRNA and immunoreactivity levels (r= -0.45, p=0.07; r= -0.455, p= 0.006, respectively). Multivariate analysis showed that serum Klotho, together with the gene expression levels of tumor necrosis factor TNFa in blood circulating cells, were independent determinants of CIMT values (adjusted R2 = 0.593, p<0.001).

Discussion

The results of this study in subjects with eGFR≥60mL/min/1.73m2 show that patients with carotid artery atherosclerosis and higher values of CIMT present reduced soluble Klotho levels, as well as decreased KL mRNA expression in peripheral blood circulating cells and Klotho protein levels in the intima-media of the carotid artery wall.

The Value of Klotho in Kidney Transplantation

Kidney transplant recipients have better survival rates and improved quality of life than long-term dialysis patients. However, delayed graft function, immunosuppressive therapy nephrotoxicity, and rejection episodes may compromise graft and patient survival. The KL gene is highly expressed in kidney tubular cells and encodes the antiaging and kidney-protective protein Klotho, which has membrane-anchored and soluble forms and regulates mineral metabolism. Klotho expression decreases during acute kidney injury or chronic kidney disease, and human chronic kidney disease shares features of accelerated aging with murine Klotho deficiency. In this work, we review clinical studies on the relationship between Klotho and kidney transplantation. Specifically, we address the dynamics of serum and kidney Klotho levels in donors and kidney transplant recipients, the role of Klotho as a marker of current graft function and graft outcomes, and the potential impact of Klotho on kidney protection in the transplantation context. A better understanding of the potential biomarker and therapeutic utility of Klotho in kidney transplant recipients may provide new insights into the control of graft function and new therapeutic strategies to preserve allograft function.

Repurposing drugs for highly prevalent diseases: pentoxifylline, an old drug and a new opportunity for diabetic kidney disease

Diabetic kidney disease is one of the most frequent complications in patients with diabetes and constitutes a major cause of end-stage kidney disease. The prevalence of diabetic kidney disease continues to increase as a result of the growing epidemic of diabetes and obesity. Therefore, there is mounting urgency to design and optimize novel strategies and drugs that delay the progression of this pathology and contain this trend. The new approaches should go beyond the current therapy focussed on the control of traditional risk factors such as hyperglycaemia and hypertension. In this scenario, drug repurposing constitutes an economic and feasible approach based on the discovery of useful activities for old drugs. Pentoxifylline is a nonselective phosphodiesterase inhibitor currently indicated for peripheral artery disease. Clinical trials and meta-analyses have shown renoprotection secondary to anti-inflammatory and antifibrotic effects in diabetic patients treated with this old known drug, which makes pentoxifylline a candidate for repurposing in diabetic kidney disease.

MO640: Treatment with Sodium–Glucose Cotransporter 2 Inhibitors Increases Klotho in Type 2 Diabetic Patients

BACKGROUND AND AIMS

Klotho (KL) is a transmembrane protein mainly expressed by the tubular cells of the kidneys, with an additional soluble form that is present in blood and urine. Preserved KL has been related to physiological protection of the kidneys. Sodium–glucose cotransporter type-2 inhibitors (SGLT2i) are a new class of anti-diabetic drugs with important renal benefits. The aim of the present study was to analyze the effect of treatment with SGLT2i on soluble KL concentrations as well as on mRNA expression levels of the KL gene in renal tubular cells.

METHOD

Fifty-seven patients (30 males and 27 females; mean age 61 ± 5 years) with type 2 diabetes and chronic kidney disease stage G2-A2, all treated with metformin and blockers of the renin–angiotensin system, were included in the study. All patients were in need of intensified anti-diabetic therapy at the discretion of their physicians in accordance with the routine clinical practice. Forty-five received SGLT2i during 3 months (15 empagliflozin, 15 canagliflozin and 15 dapagliflozin), and the evolution was compared with a group of 12 patients matched by age, sex and stage of CKD who received DPP4 inhibitors (control group). Serum and urine levels of soluble KL and tumor necrosis factor-alpha (TNFa) were determined by ELISA. In addition, the effect on mRNA expression levels of KL was assessed in vitro in renal tubular cells cultures.

RESULTS

Baseline values of serum and urinary KL and TNFa were similar in both groups. Urinary KL was inversely correlated with albuminuria (r = −0.45, P &lt; 0.001) and urine TNFa excretion (r = −0.40, P &lt; 0.01). At the end of the study, there was a similar improvement in metabolic control in both groups; however, only patients treated with SGLT2i showed a significant reduction in albuminuria and urinary TNFa (P &lt; 0.01). Serum and urinary KL increased by 5.2% and 38.9%, respectively, only in patients receiving SGLT2i (P &lt; 0.001 versus baseline), without changes in controls (P &lt; 0.01 between groups). There were no differences among the three drugs in the SGLT2i group. The reduction in albuminuria (β = −0.35, P &lt; 0.01) and urinary TNFa (β = −0.57, P &lt; 0.001) were independently associated with the increase in urine KL, while the change in albuminuria was related to the increase in serum KL (β = −0.39, P &lt; 0.05). Cultured renal tubular cells under high glucose, inflammatory stimulus with TWEAK or serum bovine albumin decreased Klotho mRNA and protein expression within 24 h, an effect that was prevented by all the SGLT2i when added to the cultures.

CONCLUSION

In type 2 diabetic patients, treatment with SGLT2i induces a reduction in albuminuria and modulates inflammation (as reflected by a decrease in the urinary excretion of TNFa), which is associated with a significant increase in soluble KL concentrations. In addition, SGLT2i prevent the reduction in protein and mRNA expression levels of the KL gene in renal tubular cells. The preservation of KL by SGLT2i may be an important mechanism of renal protection.

MO453SERUM AND VASCULAR FIBROBLAST GROWTH FACTOR 23 (FGF23) ARE ASSOCIATED WITH VASCULAR CALCIFICATION

Background and Aims

Mineral metabolism imbalances and inflammation are related to the development of vascular calcification (VC). Fibroblast growth factor-23 (FGF23) is the main regulator of phosphate homeostasis and various studies have shown the existence of an association between elevated levels of FGF23 and the appearance of cardiovascular disease (CVD). We conducted a case-control study to test the hypothesis that serum and vascular levels of FGF23 are associated with the presence of VC. In addition, we determined the influence of inflammation in these levels.

Method

One hundred and thirty-three patients diagnosed with clinical atherosclerotic disease undergoing elective vascular surgery, and 20 cadaveric organ donors with no medical history of CVD, were included in this study. Serum levels of intact FGF23 (iFGF23), together with tumor necrosis factor-alpha (TNFα), interleukin (IL)10, were determined by ELISA. Vascular fragments of aorta, carotid and femoral arteries were obtained for assaying the gene expression of FGF23, TNF, IL10 and RUNX2 by qPCR. Immunohistochemical procedures were employed to determine vascular protein levels of FGF23, TNFα and IL10. VC was diagnosed by imaging techniques and confirmed by histological procedures including von Kossa staining.

Results

Case group presented a higher prevalence of hypertension, hypercholesterolemia and reduced estimated glomerular filtration rate, with no differences regarding other parameters. Serum iFGF23 and TNFα/IL10 ratio were higher in the case group (P&lt;0.01 and P&lt;0.001, respectively). Vascular expression of FGF23 was detected in 58.6% of CVD patients vs 35% of donors, with mean expression levels significantly higher in the first group (P&lt;0.01). Vascular expression of TNF/IL10 was also increased (P&lt;0.001) in CVD patients. FGF23 immunoreactivity was detected in 84% of CVD patients and only in 35% of controls. Immunoreactivity for FGF23 and TNFα/IL10 ratio were significantly higher in CVD patients (P&lt;0.001 and P&lt;0.0001, respectively).

Stratified analysis according to serum iFGF23 levels showed a higher prevalence of VC in the upper tertiles. Patients with VC presented increased levels of all the FGF23 variables including serum [1.5 (1.2-1.6) vs. 1.4 (0.9-1.5) pg/mL, P&lt;0.01], vascular mRNA [26.1 (14.3-67.4) vs. 18.8 (8.8-312.9) log AU, P&lt;0.01] and vascular immunoreactivity [4.6 (3.8-4.9) vs. 3.7 (3.1-4.1) log µm2, P&lt;0.05]. Moreover, FGF23 immunoreactivity was detected in 92.3% of fragments with VC and only in 53.6% of those without VC. Serum TNFα/IL10 and RUNX2 mRNA levels were also higher in this group (P&lt;0.01 for both).

Correlation analysis showed associations of serum iFGF23 with serum TNFα (r=0.375, P&lt;0.001), neutrophil/lymphocyte (r=0.142, P&lt;0.05), vascular RUNX2 mRNA (r=0.55, P&lt;0.05), and vascular FGF23 immunoreactivity (r=0.281, P&lt;0.05) in the CVD group. Vascular FGF23 expression correlated with RUNX2 mRNA (r=0.315, P&lt;0.05) and FGF23 immunoreactivity (r=0.254, P&lt;0.05). Multiple regression analysis showed that iFGF23 levels were determined by UAE, HDL, FGe, calcium and TNFα levels (adjusted R2= 0.473, P&lt;0.0001) and that vascular FGF23 mRNA expression was determined by TNFα, PCR, glucose and age (adjusted R2= 0.795, P&lt;0.0001). Multivariate logistic regression, with VC as dependent variable, showed that both iFGF23 and vascular mRNA constitute independent risk factors for the existence of VC [OR (95% CI): 1.05 and 1.12, P&lt;0.05 for both].

Conclusion

Patients with atherosclerosis and VC present significantly higher serum concentrations of FGF23, as well as higher immunoreactivity and gene expression levels in the vascular wall compared to patients without VC. Moreover, both serum and vascular mRNA levels of FGF23 are associated with the inflammatory status. Whether the increase in systemic and vascular FGF23 can directly promote or favor the calcifying process in the vascular bed is currently an issue under discussion.

MO440KLOTHO AS A BIOMARKER OF SUBCLINICAL CARDIOVASCULAR DISEASE IN CHRONIC KIDNEY DISEASE: A PROOF-OF-CONCEPT STUDY*

Background and Aims

Cardiovascular disease (CVD) is the major cause of mortality among chronic kidney disease (CKD) patients. Reductions in serum Klotho levels are related to the prevalence of CVD in CKD patients. However, it is unclear whether circulating Klotho, and its expression in peripheral blood cells (PBCs), are associated with subclinical atherosclerotic cardiovascular disease (sCVD) in these subjects. In this proof-of-concept study, we analyzed in a group of CKD patients the relationship between Klotho and two markers of sCVD: ankle-brachial index (ABI) and carotid intima-media thickness (CIMT).

Method

Gene expression in PBCs and serum levels of Klotho and inflammatory cytokines (TNF, IL6 and IL10) were measured in 103 CKD patients (stages 3-4), older than 18 years of age, and without known atherosclerotic cardiovascular disease. Biochemical data were obtained following standardized clinical methods. The presence of sCVD was defined as ABI &lt; 0.9 and/or CIMT ≥ 0.9 mm. Patients with ABI values ≥ 1.3 were excluded.

Results

Patients with sCVD presented lower serum and PBCs expression levels of Klotho (P&lt;0.001 for both). Stratified analysis showed that upper tertiles of both serum and PBCs expression levels of Klotho presented significantly higher ABI (P&lt;0.001 for both Klotho determinations) and lower CIMT (P&lt;0.001 for serum levels and P&lt;0.01 for KL expression in PBCs), which resulted in a lower prevalence of sCVD (P&lt;0.001 for both determinations of Klotho).

Correlation analysis showed that both serum and PBCs mRNA Klotho levels were positively correlated with ABI (r=0.556, P&lt;0.0001; and r=0.373, P&lt;0.0001, respectively) and inversely correlated with CIMT (r=-0.541, P&lt;0.0001; and r=-0.437, P&lt;0.0001, respectively). Among inflammatory markers, only serum IL6 levels presented significant associations with sCVD, being inversely related with ABI (r=-0.568, P&lt;0.0001) and positively associated with CIMT (r=0.558, P&lt;0.0001).

Multiple regression analysis with ABI and CIMT as dependent variables demonstrated that both Klotho variables, together with serum IL6, were positively and significantly associated with ABI (adjusted R2=0.511, P&lt;0,0001) and CIMT (adjusted R2=0.445, P&lt;0,0001) values, independently of traditional and emergent cardiovascular risk factors.

Multivariate logistic regression, using the presence/absence of sCVD as the dependent variable, showed that circulating Klotho, and its expression in PBCs constituted independent protective factors for sCVD [OR (95% CI): 0.993 (P=0.002) and 0.231 (P=0.025), respectively]. Receiver operating curve (ROC) analysis pointed to the prognostic ability for sCVD of serum Klotho (area under the curve [AUC]: 0.817, 95% CI: 0.736–0.898, P&lt;0.001) and its gene expression in PBCs (AUC: 0.742, 95% CI: 0.647–0.836, P&lt;0.001).

Conclusion

The reductions in serum soluble and PBCs expression levels of Klotho in CKD patients are independently associated with the presence of sCVD. Further research exploring whether therapeutic approaches to maintain or elevate the Klotho level could reduce the impact of CVD in CKD patients is warranted.

MO037EPIGENETIC REGULATION OF KLOTHO IN PERIPHERAL BLOOD CIRCULATING CELLS IS ASSOCIATED CELLS IS ASSOCIATED WITH SOLUBLE PROTEIN SERUM IN CARDIOVASCULAR DISEASE

Background and Aims

The antiaging factor α-Klotho (KL) has been related to cardiovascular diseases (CVD), including coronary artery disease, heart failure and peripheral arterial disease. The soluble form of this protein (sKL), which is mainly produced by the kidneys, have demonstrated to display different protective effects on the cardiovascular system, e.g., prevention of vascular calcification, oxidative stress, or cardiac fibrosis. Likewise, different clinical studies have pointed out that CVD is a state of sKL deficiency, even when the renal function is still preserved. It has been demonstrated that peripheral blood circulating cells (PBCCs) also express KL, but little is known about its expression profile during CVD. The aim of this work is to determinate if the expression of KL gene and its promoter methylation in PBCCs are correlated with serum levels of the soluble protein, and if there exist any association with the underlying inflammatory process that occurs during CVD.

Method

Forty-four patients diagnosed with clinical atherosclerotic vascular disease (case group) and 15 subjects without CVD background (control group) were included in the study. Whole blood and serum samples were obtained from all participants. We performed gene expression analysis for KL expression in PBCCs by qPCR, as well as for DNMT1 and DNMT3A (members of the DNA-methyltransferases family), TNF, IL10 and NFKB1 (inflammatory parameters). We assessed the degree of methylation of the KL gene promoter in these cells by bisulfite sequencing. Furthermore, we determined circulating levels of sKL, TNFα and IL10 by ELISA immunoassay in serum samples of both groups.

Results

Results showed a lower expression of KL gene in PBCCs of patients with CVD compared to controls (45% reduction, P&lt;0.001), which was accompanied by a higher degree of methylation of its promoter (36.7±6.3% vs. 15.9±4.8%, P&lt;0.05). The case group also presented significantly higher levels of DNMT1 and DNMT3A transcripts in these cells (P&lt;0.0001 for both), as well as higher values of proinflammatory parameters (gene expression of TNF and NFKB1, and TNF/IL10 ratio; P&lt;0.001 for all of them). Serum levels of sKL were decreased in the CVD group compared to controls (a reduction of 57.5%, P&lt;0.0001). KL expression in PBCCs correlated directly with systemic levels of sKL (r=0.20, P&lt;0.05), but inversely with expression of DNMT1 (r=-0.33, P&lt;0.01) and inflammatory parameters (r=-0.37, P&lt;0.01 for NFKB1 expression; r=-0.38, P&lt;0.01 for TNF/IL10 expression ratio; and r=-0.39, P&lt;0.01 for serum TNFα/IL10 ratio). No significant associations were found between inflammatory markers and methylation degree of KL gene promoter.

Conclusion

These results indicate an association between epigenetic regulation of KL gene in PBCC and systemic levels of the soluble protein in CVD, which could be influenced by the proinflammatory state present in these disorders.

MO031KLOTHO GENE PROMOTER METHYLATION IN THE VASCULATURE IS RELATED TO INFLAMMATION IN HUMAN ATHEROSCLEROSIS

Background and Aims

Atherosclerosis, a vascular pathological process with an important inflammatory component, underlies most of the cardiovascular diseases (CVD). Deficiencies in the antiaging factor α-Klotho (KL) have been related to the appearance and progression of atherosclerotic damage associated with CVD. In addition, some studies have demonstrated that KL gene is expressed in human arteries and that low vascular KL expression levels are related with clinical atherosclerotic disease. Among the epigenetic mechanisms that regulate the expression of the KL gene, methylation of the CpG islands in the promoter region is one of the most studied. In this pilot study, we propose that this mechanism participates in the regulation of vascular KL expression and contributes to the deficiency in vascular KL levels observed in CVD. Moreover, we determined the influence of different inflammatory components in the methylation status of KL promoter.

Method

We developed a case-control study that included 25 patients with diagnosis of clinical atherosclerotic vascular disease undergoing elective vascular surgery and 15 cadaveric organ donors with no medical history of CVD, respectively. Vascular fragments were retrieved from all subjects, and the degree of methylation of the KL gene promoter was assessed by bisulfite sequencing. Additionally, vascular gene expression in both groups was assessed by qPCR for KL, two DNA methyltransferases (DNMT1 and DNMT3A), and three inflammatory-related loci (TNF, IL10 and NFKB1). Serum concentrations of TNFα and IL10 were measured by ELISA immunoassay, and complementary inflammatory parameters (CRP and neutrophil/lymphocyte ratio) by standardized routine methods.

Results

The vascular tissue of patients in the case group presented a higher percent level of methylated positions in the KL promoter region (71.4±8.3% vs. 39.4±12.3%, P&lt;0.05), as well as a significant decrease in the expression of KL gene (a 40% reduction as compared to controls, P&lt;0.05). Considering the whole study population, the methylation degree was inversely related to the endogenous transcript levels of KL gene (r=-0.66, P&lt;0.0001). Moreover, the expression of DNMT1 was significantly increased in the case group (P&lt;0.05), as well as those of the proinflammatory genes TNF and NFKB1 (P&lt;0.0001 and P&lt;0.05, respectively), being all of them directly associated with the vascular methylation levels of KL gene (r=0.51, P&lt;0.0001 for DNMT1; r=0.45, P&lt;0.001 for TNF; r= 0.37, P&lt;0.05 for NFKB1). Furthermore, vascular expression of DNMT1 and DNMT3A directly correlated with both inflammatory markers in this tissue (P&lt;0.0001, for all). Systemic levels of IL10 presented a direct association with vascular KL gene expression (r=0.28, P&lt;0.05), while inverse associations were observed with the methylation degree of KL gene (r=-0.38, P&lt;0.05) and DNMT1 expression (r=-0,29, P&lt;0.05).

Conclusion

These results suggest that the methylation of KL gene promoter in the vasculature is a mechanism associated with the inflammatory response that would partly explain its reduction during atherosclerotic injury.

Inflammatory Cytokines in Diabetic Kidney Disease: Pathophysiologic and Therapeutic Implications

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease and a main contributing factor for cardiovascular morbidity and mortality in patients with diabetes mellitus. Strategies employed to delay the progression of this pathology focus on the control of traditional risk factors, such as hyperglycemia, and elevated blood pressure. Although the intimate mechanisms involved in the onset and progression of DKD remain incompletely understood, inflammation is currently recognized as one of the main underlying processes. Untangling the mechanisms involved in the appearing of a harmful inflammatory response in the diabetic patient is crucial for the development of new therapeutic strategies. In this review, we focus on the inflammation-related pathogenic mechanisms involved in DKD and in the therapeutic utility of new anti-inflammatory strategies.