Long-Term Progression of Coronary Artery Calcification Is Independent of Classical Risk Factors, C-Reactive Protein, and Parathyroid Hormone in Renal Transplant Patients

Vascular calcification progression and its association with mineral and bone disorder in kidney transplant recipients

BACKGROUND

The assessment and prevention of vascular calcification (VC) in kidney transplant recipients (KTRs) have not been systematically studied. We aimed to evaluate VC change one year after kidney transplantation (KT) and identify their influencing factors.

METHODS

95 KTRs (68 males; ages 40.2 ± 10.8 years) were followed one year after KT. Changes in bone mineral density (BMD) and bone metabolism biomarkers were assessed. Coronary artery calcification (CAC) and thoracic aortic calcification (TAC) were measured using 192-slice third-generation dual-source CT. The relationship between bone metabolism indicators and VC and the factors influencing VC were analyzed.

RESULTS

Postoperative estimated glomerular filtration rate was 79.96 ± 24.18 mL/min*1.73 m2. One year after KT, serum phosphorus, intact parathyroid hormone (iPTH), osteocalcin, type I collagen N-terminal peptide (NTx), type I collagen C-terminal peptide, and BMD decreased, 25-hydroxyvitamin D remained low, and VC increased. Post-CAC and TAC were negatively correlated with pre-femoral neck BMD, and TAC was positively correlated with post-calcium. CAC and TAC change were positively correlated with post-calcium and 25-hydroxyvitamin D. Increased CAC was positively associated with hemodialysis and pre-femoral neck osteopenia. CAC change was positively associated with prediabetes, post-calcium, and pre-CAC and negatively associated with preoperative and postoperative femoral neck BMD, and NTx change. Increased TAC was positively associated with age, prediabetes, preoperative parathyroid hyperplasia/nodule, post-calcium, and post-femoral neck osteopenia. TAC change was positively associated with age, diabetes, pre-triglyceride, pre-TAC, dialysis time, post-calcium and post-iPTH, and negatively associated with post-femoral neck BMD.

CONCLUSIONS

Mineral and bone disorders persisted, and VC progressed after KT, showing a close relationship.

Vitamin K1 and K2 in the Diet of Patients in the Long Term after Kidney Transplantation

Vitamin K, especially its K2 form, is considered to be a protective factor against developing vascular changes and bone lesions that are common complications in kidney transplant (KTx) recipients. There is a growing number of studies showing that KTx patients are at risk of vitamin K deficiency. The aim of this study was to evaluate the intake of vitamin K1 and K2 in the diet of patients in the late period after KTx. During a routine visit at one outpatient transplantation clinic in Central Europe, a diet survey questionnaire was filled in by 151 clinically stable KTx recipients and compared with medical history, anthropometric measurements and laboratory tests. Mean vitamin K1 intake was 120.9 ± 49 μg/day and vitamin K2 (MK, menaquinone) intake 28.69 ± 11.36 μg/day, including: MK-4: 25.9 ± 9.9 μg/day; MK-5: 0.1 ± 0.2 μg/day; MK-6: 0.2 ± 0.4 μg/day; MK-7: 0.2 ± 0.23 μg/day; MK-8: 1 ± 1.9 μg/day; MK-9: 0.9 ± 2.3 μg/day; and MK-10: 0.2 ± 0.5 μg/day. Our study showed that KTx recipients' diets contained adequate amounts of vitamin K1, whereas the intake of vitamin K2 seemed insufficient.

Coronary artery calcification progression and long-term cardiovascular outcomes in renal transplant recipients: an analysis by the joint model

Background

Compared with the general population, the risk of death is substantially higher in renal transplant recipients than in age- and sex-matched individuals in the general population. In the general population, coronary artery calcification (CAC) predicts all-cause and cardiovascular mortality. In this study we aimed to analyse these relationships in renal transplant recipients.

Methods

We examined 178 renal transplant patients in this prospective observational cohort study. We measured CAC with multidetector spiral computed tomography using the Agatston score at multiple time points. Overall, 411 scans were performed in 178 patients over an average 12.8 years follow-up. The clinical endpoint was a composite including all-cause death and non-fatal cardiovascular events. Data analysis was performed by the joint model.

Results

During a follow-up of 12.8 ± 2.4 years, coronary calcification progressed over time (P < 0.001) and the clinical endpoint occurred in 54 patients. In the analysis by the joint model, both the baseline CAC score and the CAC score progression were strongly associated with the incidence rate of the composite event [hazard ratio 1.261 (95% confidence interval 1.119–1.420), P = 0.0001].

Conclusions

CAC at baseline and coronary calcification progression robustly predict the risk of death and cardiovascular events in renal transplant recipients. These findings support the hypothesis that the link between the calcifying arteriopathy of renal transplant patients and clinical end points in these patients is causal in nature.

Association of cystatin C with coronary artery calcification in patients undergoing multidetector computed tomography

Cystatin C is associated with atherosclerosis, but the relationship between cystatin C and coronary artery calcification (CAC) is uncertain. The purpose of this study was to evaluate the predictive value of cystatin C on the occurrence and severity of CAC.A total of 1447 hospitalized patients with coronary computed tomography angiography were selected in this study. According to the CAC score (CACS), patients were divided into calcification group (with CAC, n = 749) and control group (without CAC, n = 698). The calcification group was further divided into low calcification group (CACS < 100, n = 407), medium calcification group (CACS 100-400, n = 203), and high calcification group (CACS≥400, n = 139).Patients with CAC had higher cystatin C level than those in control group (P < .05). With the increase of calcification score, the cystatin C level showed an upward trend. The cystatin C level in the high calcification group was significantly higher than those in the low and medium calcification group (P < .05). ROC curve analysis showed that cystatin C had a high predictive value for the occurrence of CAC [area under the curve 0.640, 95% confidence interval (95% CI) 0.591-0.690, cut-off value 0.945 mg/L, sensitivity 0.683, specificity 0.558, P < .05] and severe CAC (area under the curve 0.638, 95% CI 0.550-0.762, cut-off value 0.965 mg/L, sensitivity 0.865, specificity 0.398, P < .05). Multivariate logistic regression analysis showed that cystatin C was an independent predictor of severe CAC (AOR 3.748, 95% CI 1.138-10.044, P < .05).Cystatin C was significantly associated with the occurrence and severity of CAC, suggesting that cystatin C had the potential as a predictor of CAC.

Uremic Toxins and Vascular Calcification-Missing the Forest for All the Trees

The cardiorenal syndrome relates to the detrimental interplay between the vascular system and the kidney. The uremic milieu induced by reduced kidney function alters the phenotype of vascular smooth muscle cells (VSMC) and promotes vascular calcification, a condition which is strongly linked to cardiovascular morbidity and mortality. Biological mechanisms involved include generation of reactive oxygen species, inflammation and accelerated senescence. A better understanding of the vasotoxic effects of uremic retention molecules may reveal novel avenues to reduce vascular calcification in CKD. The present review aims to present a state of the art on the role of uremic toxins in pathogenesis of vascular calcification. Evidence, so far, is fragmentary and limited with only a few uremic toxins being investigated, often by a single group of investigators. Experimental heterogeneity furthermore hampers comparison. There is a clear need for a concerted action harmonizing and standardizing experimental protocols and combining efforts of basic and clinical researchers to solve the complex puzzle of uremic vascular calcification.

Hypercalcemia Is a Risk Factor for the Progression of Aortic Calcification in Kidney Transplant Recipients

BACKGROUND/AIMS

Vascular calcification is common and progressive in chronic kidney disease, including kidney transplant recipients (KTRs). However, the risk factors associated with the progression of aortic calcification (AoC) in KTRs have not been fully elucidated. In the present study, we evaluated AoC and examined the factors associated with its advancement in KTRs.

MATERIALS

This was a prospective longitudinal study that included 98 KTRs. We quantitatively investigated infrarenal abdominal AoC using the Agatston score, as measured by multi-slice computed tomography. After the baseline investigation, a follow-up scan was performed after 3 years, and the Agatston scores were obtained again. The changes in laboratory data affecting the 2nd Agatston scores were examined by multivariable analysis using non-linear regression after adjustment for several confounders.

RESULTS

The 2nd Agatston scores were significantly greater than the baseline Agatston scores (p < 0.001). After adjustment for the confounders, the change in corrected serum calcium exhibited a significant non-linear correlation with the 2nd Agatston scores (p = 0.022 for non-linearity/p = 0.031 for the effect of corrected serum calcium). Moreover, an interaction was present from the baseline AoC in the effect of corrected serum calcium on the progression of AoC, and the effect of hypercalcemia was greater in patients with higher baseline Agatston scores (p = 0.049).

CONCLUSION

The present study revealed that hypercalcemia is a risk factor for the development of infrarenal abdominal AoC in KTRs. Furthermore, the effect of hypercalcemia was greater in patients with more severe vascular calcification.

Joint association of vitamins D and K status with long-term outcomes in stable kidney transplant recipients

Background

Kidney transplant recipients (KTRs) experience substantial survival benefit compared with dialysis patients. However, their mortality and graft failure risk remain high. KTRs are often low in micronutrient status, including vitamins D and K. We investigated the association of both vitamins D and K status, and vitamin D treatment with all-cause mortality and death-censored graft failure.

Methods

We studied 461 KTRs from a single-centre study at median 6.1 years after transplantation. At baseline, vitamins D and K concentrations were measured by 25-hydroxyvitamin D [25(OH)D] and dephosphorylated uncarboxylated matrix gla protein (dp-ucMGP) and patients were categorized into: 25(OH)D &lt;50/≥50 nmol/L and median dp-ucMGP &lt;1057/≥1057 pmol/L.

Results

Mean age was 52 ± 12 years, and 122 KTRs (26%) had low vitamins D and K status. During median 9.8 years follow-up, 128 patients (28%) died and 48 (10%) developed death-censored graft failure. Low vitamins D and K status was associated with 2.33 (1.26–4.30) [hazard ratio (95% confidence interval)] increased mortality risk and 3.25 (1.17–9.08) increased graft failure risk compared with KTR with 25(OH)D ≥50 nmol/L and dp-ucMGP &lt;1057 pmol/L. Dp-ucMGP was strongly associated with mortality (per 500 pmol/L increase): 1.41 (1.08–1.41) for vitamin D treatment versus no treatment 1.07 (0.97–1.18), and graft failure 1.71 (1.17–2.49) for vitamin D treatment versus 1.19 (1.05–1.36) no treatment, P-interaction &lt;0.07 for vitamin D treatment (n = 44).

Conclusions

Combined vitamins D and K deficiency are highly prevalent and are associated with increased mortality and graft failure risk compared with high vitamins D and K status. Low vitamin K status was strongly associated with an increased risk of premature mortality and graft failure for patients treated with vitamin D versus no vitamin D treatment.

Alteration of serum immunoglobins, C-reactive protein, vitamin D, and electrolyte by atenolol and amlodipine in stress-induced hypertensive rats

The present study is designed for the assessment of various pathological changes like immunoglobins, C-reactive protein, vitamin D, sodium, potassium, calcium in stress-induced hypertensive rats. Albino Wistar rats of sex male were grouped into six. Each group consists of six animals. Groups were Group I (normal control), Group II (disease control), Group III (amlodipine control), Group IV (atenolol control), Group V (amlodipine treatment), and Group VI (atenolol treatment). Group II, V, and VI animals exposed to regular stress by placing them in cages individually and giving foot electric shocks (1 mA, 50 ms duration with 0.5-1 min of intervals regulated randomly by a computer) along with forced swimming (30 min) in order to induce hypertension in rats. This stress was given two times daily (morning and evening) for regular 15 days. Induction of hypertension was confirmed by measuring the tail arterial pressure of blood and angiotensin II. For next 1 month, Group III and V animals are treated with amlodipine with 1 mg/kg, s.c. dose while Group IV and VI animals were given 10 mg/kg, s.c. the dose of atenolol once daily. At the end of the experimental work, blood collected, rats sacrificed, and serum separated. Serum sodium, potassium, immunoglobins, C-reactive protein, vitamin D, and calcium were measured by semi-auto-analyzer. Stress-induced hypertension in rats produced altered serum sodium, potassium, immunoglobins, C-reactive protein, vitamin D, and calcium level which is restored by atenolol. Administration of amlodipine in animals without hypertension shows alteration in the level of immunoglobins, calcium, vitamin D, and electrolytes.