The Vitamin D Receptor Activator Maxacalcitol Provides Cardioprotective Effects in Diabetes Mellitus

Potential Actions of Baicalein for Preventing Vascular Calcification of Smooth Muscle Cells In Vitro and In Vivo

Vascular calcification (VC) is associated with cardiovascular disease. Baicalein, a natural flavonoid extract of Scutellaria baicalensis rhizome has several biological properties which may inhibit VC. We investigated whether baicalein suppresses Runt-related transcription factor 2 (Runx2) and bone morphogenetic protein 2 (BMP-2) and upregulates smooth muscle 22-alpha (SM22-α) and alpha-smooth muscle actin (α-SMA). In an in vitro experiment, primary rat aortic vascular smooth muscle cells (VSMCs) were pretreated with 0.1, 1, and 5 μM baicalein, followed by β-glycerophosphate (β-GP) to induce calcification. In an in vivo experiment, VC was generated by vitamin D3 plus nicotine (VDN) administration to male Sprague Dawley (SD) rats randomly assigned into a control group, a VC group, a VC group pretreated with baicalein, and a baicalein alone group. Each group comprised 10 rats. Left ventricular (LV) morphology, function and performance were assessed by echocardiography. Calcium content was measured by Alizarin red S staining and alkaline phosphatase (ALP) activity assays. Apoptotic VSMCs were detected by flow cytometry. Protein levels and superoxide changes were evaluated using Western blotting and immunofluorescence assays respectively. Plasma malondialdehyde (MDA) was assayed. Baicalein pretreatment significantly reduced calcium content in calcified VSMCs (p < 0.001) as well as in VC rat aortic smooth muscle (p < 0.001). Additionally, ALP activity was decreased in calcified VSMCs and VC rat aortic smooth muscle (p < 0.001). Apoptosis was significantly attenuated by 1 μM baicalein pretreatment in calcified VSMCs. Runx2 and BMP-2 expressions were downregulated by the baicalein in calcified VSMCs. Baicalein pretreatment increased typical VSMCs markers SM22-α and α-SMA in calcified VSMCs. Baicalein pretreatment was associated with adverse changes in LV morphometry. Markers of oxidative stress declined, and endogenous antioxidants increased in VC rats pretreated with baicalein. Baicalein mitigates VC through the inhibition of Runx2/BMP-2 signaling pathways, enhancement of vascular contractile phenotype and oxidative stress reduction. However, our study is of basic experimental design; more advanced investigations to identify other molecular regulators of VC and their mechanisms of action is required.

Changes of FGF23 and the Renin-Angiotensin-System in Male Mouse Models of Chronic Kidney Disease and Cardiac Hypertrophy

Serum fibroblast growth factor 23 (FGF23) levels and the renin-angiotensin-aldosterone system (RAAS) are elevated in chronic kidney disease (CKD) patients, and their association with left ventricular hypertrophy (LVH) has been reported. However, whether the FGF23 elevation is the cause or result of LVH remains unclear. At 10 weeks, male C57BL/6J mice were divided into 4 groups: sham, CKD (5/6 nephrectomy), LVH (transaortic constriction), and CKD/LVH group. At 16 weeks, the mice were euthanized, and blood and urine, cardiac expressions of FGF23 and RAAS-related factors, and cardiac histological analyses were performed. Heart weight, serum FGF23 levels, and cardiac expression of FGF23 and RAAS-related factors, except for angiotensin-converting enzyme 2, were more increased in the CKD/LVH group compared to the other groups. A significant correlation between LVH and cardiac expressions of FGF23 and RAAS-related factors was observed. Furthermore, there was a significantly close correlation of the cardiac expression of FGF23 with LVH and RAAS-related factors. The coexisting CKD and LVH increased serum and cardiac FGF23 and RAAS-related factors, and there was a significant correlation between them. A close correlation of cardiac, but not serum FGF23, with LVH and RAAS suggests that local FGF23 levels may be associated with LVH and RAAS activation.

Influence of oxidative stress on vascular calcification in the setting of coexisting chronic kidney disease and diabetes mellitus

Vascular calcification (VC) is a common complication in patients with chronic kidney disease (CKD). Particularly, CKD patients with diabetes mellitus (DM) develop severe VC. Specific mechanisms of VC remain unclear; this study aimed to investigate them in the context of coexisting CKD and DM, mainly regarding oxidative stress. Sprague Dawley rats were randomly divided into six groups as follows: control rats (Control), 5/6 nephrectomized rats (CKD), streptozotocin-injected rats (DM), 5/6 nephrectomized and streptozotocin-injected rats (CKD + DM), CKD + DM rats treated with insulin (CKD + DM + INS), and CKD + DM rats treated with antioxidant apocynin (CKD + DM + APO). At 18 weeks old, the rats were sacrificed for analysis. Compared to the control, DM and CKD groups, calcification of aortas significantly increased in the CKD + DM group. Oxidative stress and osteoblast differentiation-related markers considerably increased in the CKD + DM group compared with the other groups. Moreover, apocynin considerably reduced oxidative stress, osteoblast differentiation-related markers, and aortic calcification despite high blood glucose levels. Our data indicate that coexisting CKD and DM hasten VC primarily through an increase in oxidative stress; anti-oxidative therapy may prevent the VC progression.

Resistin as a predictor of cardiovascular hospital admissions and renal deterioration in diabetic patients with chronic kidney disease

BACKGROUND

High resistin levels have been associated with cardiovascular disease (CVD). Cardiovascular hospitalizations are common, especially in diabetic and renal impaired patients. The purpose of this study is to determine the role of serum resistin as a predictor of cardiovascular hospitalizations in type 2 diabetic patients with mild to moderate chronic kidney disease (CKD).

METHODS

We conducted a prospective, observational study. 78 diabetic patients with mild to moderate CKD and no previous CVD were included. The population was divided in two groups: G-1 with cardiovascular related admission (n = 13) and G-2 without cardiovascular related admission (n = 65). A Student's t-test was conducted to determine correlations between laboratory findings and hospitalization. We used logistic regression to assess predictors of cardiovascular events requiring hospitalization and Cox regression to identify predictors of end-stage renal disease (ESRD).

RESULTS

eGFR, albumin, HbA1c, phosphorous, PTH, IR, CRP, resistin and active vitamin D, were related to cardiovascular admissions. In a multivariate regression model, resistin (OR = 2.074, p = 0.047) was an independent predictor of cardiovascular hospitalization. Cox regression showed that resistin (HR = 1.931, p = 0.031) and UACr (HR = 1.151, p = 0.048) were also independent predictors of renal disease progression.

CONCLUSION

Resistin demonstrated to be valuable in predicting hospital admissions and progression to ESRD.

Vitamin D deficiency and hepatitis viruses-associated liver diseases: A literature review

The secosteroid hormone vitamin D has, in addition to its effects in bone metabolism also functions in the modulation of immune responses against infectious agents and in inhibiting tumorigenesis. Thus, deficiency of vitamin D is associated with several malignancies, but also with a plethora of infectious diseases. Among other communicable diseases, vitamin D deficiency is involved in the pathogenesis of chronic liver diseases caused by hepatitis B and C viruses (HBV, HCV) and high prevalence of vitamin D deficiency with serum levels below 20 mg/mL in patients with HBV and HCV infection are found worldwide. Several studies have assessed the effects of vitamin D supplementation on the sustained virological response (SVR) to interferon (IFN) plus ribavirin (RBV) therapy in HBV and HCV infection. In these studies, inconsistent results were reported. This review addresses general aspects of vitamin D deficiency and, in particular, the significance of vitamin D hypovitaminosis in the outcome of HBV- and HCV-related chronic liver diseases. Furthermore, current literature was reviewed in order to understand the effects of vitamin D supplementation in combination with IFN-based therapy on the virological response in HBV and HCV infected patients.

Vitamin D Receptor: A Novel Therapeutic Target for Kidney Diseases

BACKGROUND

Kidney disease is a serious problem that adversely affects human health, but critical knowledge is lacking on how to effectively treat established chronic kidney disease. Mounting evidence from animal and clinical studies has suggested that Vitamin D Receptor (VDR) activation has beneficial effects on various renal diseases.

METHODS

A structured search of published research literature regarding VDR structure and function, VDR in various renal diseases (e.g., IgA nephropathy, idiopathic nephrotic syndrome, renal cell carcinoma, diabetic nephropathy, lupus nephritis) and therapies targeting VDR was performed for several databases.

RESULT

Included in this study are the results from 177 published research articles. Evidence from these papers indicates that VDR activation is involved in the protection against renal injury in kidney diseases by a variety of mechanisms, including suppression of RAS activation, anti-inflammation, inhibiting renal fibrogenesis, restoring mitochondrial function, suppression of autoimmunity and renal cell apoptosis.

CONCLUSION

VDR offers an attractive druggable target for renal diseases. Increasing our understanding of VDR in the kidney is a fertile area of research and may provide effective weapons in the fight against kidney diseases.

Role of Vitamin D in Cardiovascular Diseases

Vitamin D is critical in mineral homeostasis and skeletal health and plays a regulatory role in nonskeletal tissues. Vitamin D deficiency is associated with chronic inflammatory diseases, including diabetes and obesity, both strong risk factors for cardiovascular diseases (CVDs). CVDs, including coronary artery disease, myocardial infarction, hypertrophy, cardiomyopathy, cardiac fibrosis, heart failure, aneurysm, peripheral arterial disease, hypertension, and atherosclerosis, are major causes of morbidity and mortality. The association of these diseases with vitamin D deficiency and improvement with vitamin D supplementation suggest its therapeutic benefit. The authors review the findings on the association of vitamin D deficiency and CVDs.

Vitamin D and K signaling pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a primary liver malignancy, and is now the six most common in between malignancies. Early diagnosis of HCC with prompt treatment increases the opportunity of patients to survive. With the advances in understanding the molecular biology of HCC, new therapeutic strategies to treat HCC have emerged. There is a growing consensus that vitamins are important for the control of various cancers. Biochemical evidence clearly indicates that HCC cells are responsive to the inhibitory effect of vitamin D, vitamin D analogues and vitamin K. In this review, we summarize the mechanisms used by vitamin D and K to influence the development of HCC and the latest development of vitamin analogues for potential HCC therapy.

Comparison of the effects of novel vitamin D receptor analog VS-105 and paricalcitol on chronic kidney disease-mineral bone disorder in an experimental model of chronic kidney disease

When using vitamin D, the most important clinical problems are hypercalcemia, hyperphosphatemia, and vascular calcification. VS-105 is a novel vitamin D receptor (VDR) analog. In the present study, we compared the effects of VS-105 and paricalcitol on chronic kidney disease-mineral bone disorder (CKD-MBD) in a CKD rat model. We used male Sprague-Dawley (SD) rats and performed 5/6 nephrectomy at 8-9 weeks. At 10 weeks, the rats were classified into five groups and administered vehicle, low-dose paricalcitol (LP, 0.1μg/kg), high-dose paricalcitol (HP, 0.3μg/kg), low-dose VS-105 (LV, 0.2μg/kg), and high-dose VS-105 (HV, 0.6 μg/kg) three times a week for 10 weeks. There were no significant differences in blood pressure or renal function among the five groups. Alhough serum calcium levels were comparable between the LP and LV groups, they were higher in the HP group than in the HV group. Serum phosphate levels were higher in the paricalcitol-treated groups than in the VS-105-treated groups and paticularly higher in the HP group than in the other groups. The urinary excretion of phosphate was greater in the VS-105-treated groups than in the paricalcitol-treated groups. Serum parathyroid hormone (PTH) levels decreased and serum fibroblast growth factor-23 (FGF23) levels were elevated after administering paricalcitol and VS-105; however, serum FGF23 levels were remarkably elevated in the paricalcitol-treated groups. Further biochemical analyses revealed that the calcium content of the aorta was higher in the paricalcitol-treated groups than in the VS-105-treated group. VDR and Klotho expression in the kidney was significantly higher in the VS-105-treated groups than in the paricalcitol-treated groups although both agents increased these expressions. Our data suggest that VS-105 had a lesser effect on CKD-MBD than paricalcitol except in the case of serum PTH levels. The mechanism appears to be associated with the difference in VDR and Klotho expression.

Mineral metabolism and cardiovascular disease in CKD

The mineral bone disorder of CKD, called Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), has a major role in the etiology and progression of cardiovascular disease in CKD patients. Since the main emphasis in CKD-MBD is on three categories (bone abnormalities, laboratory abnormalities, and vascular calcifications), we have routinely accepted ectopic cardiovascular calcifications as a central risk factor in the pathophysiology of CKD-MBD for cardiac events. However, recent compelling evidence suggests that some CKD-MBD-specific factors other than vascular calcification might contribute to the onset of cardiovascular disease. Most notable is fibroblast growth factor-23 (FGF23), which is thought to be independently associated with cardiac remodeling. Slow progression of cardiac disorders, such as vascular calcification and cardiac remodeling, characterizes cardiac disease due to CKD-MBD. In contrast, fatal arrhythmia may be induced when QT prolongation occurs with CKD-MBD treatment, such as with lower Ca dialysate or the use of calcimimetics. Sudden onset of fatal cardiac events, such as heart failure and sudden cardiac death, due to fatal arrhythmia would be another distinctive phenomenon of CKD-MBD. This may be defined as CKD-MBD-specific cardiac complex syndrome.

Association of vitamin D deficiency with hepatitis B virus - related liver diseases

Background

As an immune modulator, vitamin D is involved in various pathophysiological mechanisms in a plethora of diseases. This study aims to correlate the vitamin D deficiency status and clinical progression of liver diseases associated with hepatitis B virus (HBV) infection in patients in Vietnam and to compare it to healthy controls.

Methods

We quantified the levels of total vitamin D [25-(OH) D2 and D3] in serum samples from 400 HBV patients (chronic hepatitis B infection [CHB], n = 165; HBV-associated liver cirrhosis [LC], n = 127; HBV-associated hepatocellular carcinoma [HCC], n = 108) and 122 unrelated healthy controls (HC). Univariate and multivariate analyses were performed in order to determine the association between vitamin D levels and distinct clinical parameters.

Results

The prevalence of vitamin D inadequacy (<30 ng/mL) was high among healthy individuals (81.7 %) as well as in HBV patients (84.3 %). Vitamin D deficiency (<20 ng/ml) or severe deficiency (<10 ng/ml) was observed more frequently among HBV patients (52 %) and subgroups (CHB, 47.8 %; LC, 54.4 %; HCC, 55.3 %) compared to the control group (32.5 %) (P < 0.001). Vitamin D levels and HBV-DNA load were strongly and inversely correlated (rho = −0.57, P < 0.0001). Multivariate regression analysis also revealed an independent association of HBV-DNA loads with low vitamin D levels (P = 0.0004). In addition, reduced vitamin D levels were associated with significant clinical progression of LC (Child-Pugh C versus Child-Pugh A, P = 0.0018; Child-Pugh C versus Child-Pugh B, P = 0.016).

Conclusions

Vitamin D deficiency was observed in the majority of HBV-infected patients and associated with adverse clinical outcomes. Our findings suggest that substitution of vitamin D may be a supportive option in the treatment of chronic liver diseases, in particular of HBV-associated disorders.