Effect of cholecalciferol on vitamin D-regulatory proteins in monocytes and on inflammatory markers in dialysis patients: A randomized controlled trial

The Expression of Vitamin D Receptor on Peripheral Blood Mononuclear Cells in Patients with Psoriasis

Vitamin D plays an important role in psoriasis, but its involvement in pathogenesis remains unclear. This study aimed to evaluate vitamin D receptor (VDR) expression on peripheral blood mononuclear cells (PBMCs) in patients with psoriasis and healthy controls and to study the effects of the Etanercept treatment on VDR expression on PBMCs in patients with psoriasis. Twenty patients with moderate to severe psoriasis received treatment with Etanercept for 24 weeks. The age- and sex-matched controls did not receive any intervention. VDR expression on CD3+ lymphocytes and CD14+ monocytes, and serum levels of total and free 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxy vitamin D (1,25(OH)2D) were analyzed at baseline, after 10-12 weeks, and after 24 weeks in both groups. VDR expression was analyzed using flow cytometry. We observed higher expression of the VDR on CD14+ monocytes in psoriasis patients compared to healthy controls at baseline. This difference was no longer significant after 24 weeks of the Etanercept treatment. The patients with psoriasis improved clinically. However, VDR expression was unaltered during the Etanercept treatment, and there was no correlation between VDR expression and disease severity.

Effects of active vitamin D analogs and calcimimetic agents on PTH and bone mineral biomarkers in hemodialysis patients with SHPT: a network meta-analysis

OBJECTIVE

Active vitamin D analogs and calcimimetic agents are primary drugs for patients with secondary hyperparathyroidism. Due to the different pharmacological mechanisms, they have different effects on the level of parathyroid hormone, serum calcium, phosphorus, and bone turnover biomarkers. This study aimed to evaluate the active vitamin D analogs and calcimimetic agents in hemodialysis patients with secondary hyperparathyroidism.

METHODS

We included randomized clinical trials of hemodialysis patients with secondary hyperparathyroidism, comparing active vitamin D analogs to calcimimetic agents or placebo/control. The primary outcome was the change of PTH level from baseline to end-up. The secondary outcome was the change in serum calcium, phosphorus, calcium-phosphorus product, and bone turnover biomarkers. A network meta-analysis method was applied to complete this study. The forest plots reflected statistical differences in the outcomes between active vitamin D analogs and calcimimetic agents. The SUCRA result presented the ranking of impact on the outcomes.

RESULTS

Twenty-one randomized clinical trials with 4653 patients were included in this network meta-analysis. Global and splitting-node inconsistencies provided no evidence of inconsistency in this study. There was no statistical difference between two active vitamin D analogs and three calcimimetic agents in the PTH, and phosphorus levels changed. Considering serum calcium level, compared with placebo, calcitriol (9.73, 3.09 to 16.38) and paricalcitol (9.74, 3.87 to 15.60) increase serum calcium. However, cinacalcet (- 1.94, - 3.72 to - 0.15) and etelcalcetide (- 7.80, - 11.80 to - 3.80) reduced the serum calcium, even a joint use of cinacalcet with active vitamin D analogs (- 5.83, - 9.73 to - 1.93). Three calcimimetic agents decreased calcium levels much more than calcitriol and paricalcitol. The same type of drugs was not distinct, with each one affecting the change in calcium level. Cinacalcet reduced calcium-phosphorus product much more than paricalcitol (- 3.66, - 6.72 to - 0.60). Evocalcet decreased calcium-phosphorus product more than cinacalcet (- 5.64, - 8.91 to - 2.37), calcitriol (- 9.36, - 14.81 to - 3.92), and paricalcitol (- 9.30, - 13.78 to - 4.82). Compared with paricalcitol, cinacalcet significantly increases the level of ALP (24.50, 23.05 to 25.95) and bALP (0.67, 0.03 to 1.31). The incidence of gastrointestinal disorders in cinacacet (29.35, 1.71 to 504.98) and etelcalcetide (20.92, 1.20 to 365.68) was notably higher than in paricalcitol. Etelcalcetide (0.71, 0.53 to 0.96) and evocalcet (0.46, 0.33 to 0.64) presented a lower rate of gastrointestinal disorders than cinacalcet. Cinacalcet ranked first in adverse gastrointestinal, nervous, and respiratory reactions.

CONCLUSION

The same kinds of agents perform similar efficacy on the level of PTH, serum calcium, phosphorus, and calcium-phosphorus product. Paricalcitol did not lead to more hypercalcemia than calcitriol. The calcium decrease induced by cinacalcet was not settled even by associating it with active vitamin D analogs. Cinacalcet and evocalcet were superior to calcitriol and paricacitol in reducing calcium-phosphorus product. Calcimimetics induced more gastrointestinal disorders than active vitamin D analogs, especially cinacalcet.

Chronic kidney diseases and inflammation research: a bibliometric analysis

Background

Chronic kidney diseases (CKD) is a severe public health problem. This study aimed to explore the field of inflammation-related research in CKD from a bibliometric perspective.

Methods

Relevant literature published between 2004 and 2023 were searched from the Web of Science database. The bibliometric analysis were performed to summarize countries, institutions, authors, journals and keywords using VOSviewer and CiteSpace.

Results

A total of 9,287 publications on CKD and inflammation were included. Publications were mainly from the United States, China, Italy, Germany, and Japan. The findings revealed that the United States had the highest number of publications in this field, followed by China. There is strong collaboration between the two countries. The most productive institutions included the University of California system and the US Department of Veterans Affairs. Research hotspots primarily focused on inflammation mechanisms, biomarkers, and interventions.

Conclusion

This study revealed the basic knowledge structure and provided a comprehensive insight into the research field of CKD and inflammation through bibliometric methods. Future studies should focus on early diagnosis, prevention, and treatment strategies of CKD, and explore more inflammation associated biomarkers and therapeutic targets for CKD.

The interplay between vitamin D status, subclinical inflammation, and prediabetes

Vitamin D's role extends beyond classical calcium and phosphate homeostasis to encompass a pivotal influence on immune modulation and metabolic health. The mechanisms by which vitamin D exerts these effects involve its conversion to hormonally active calcitriol, which binds intracellular vitamin D receptors, initiating various downstream cascades. In this review, we tease out the evidence showing the relationship between vitamin D deficiency and prediabetes within the context of subclinical inflammation, with a special focus on the novel monocyte-to-HDL ratio (MHR), a novel inflammatory marker reflecting subclinical inflammation. This was based on a thorough literature review using reputable databases covering the period from 1980 to 2024. In light of this, we discuss calcitriol's anti-inflammatory effects and consequently link vitamin D deficiency to both overt and subclinical inflammation. Additionally, the utility of several biomarkers, notably MHR, in investigating this association is also discussed. We further reviewed the role of vitamin D deficiency in precipitating prediabetes and type 2 diabetes mellitus (T2DM) via insulin resistance, decreased insulin synthesis and secretion, and subclinical inflammation. Taken together, this mini review highlights that vitamin D deficiency is significantly associated with subclinical inflammation, playing a critical role in the development of prediabetes and the progression to T2DM. Addressing vitamin D deficiency through appropriate interventions may serve as a preventative measure against the development of prediabetes and T2DM.

Dietary Micronutrient Intake and Its Relationship with the Malnutrition-Inflammation-Frailty Complex in Patients Undergoing Peritoneal Dialysis

BACKGROUND

The relationship between dietary patterns and the malnutrition-inflammation-frailty complex in patients undergoing peritoneal dialysis (PD) is currently unknown. Our objective was to measure dietary nutrient intake and evaluate its association with malnutrition, inflammation, and frailty.

METHODS

We prospectively recruited adult PD patients. We assessed their dietary nutrient intake using a food frequency questionnaire. Frailty, malnutrition, and inflammation were evaluated by validated Frailty Score (FQ), Subjective Global Assessment (SGA), and Malnutrition-Inflammation Score (MIS).

RESULTS

A total of 209 patients were recruited for the study. Among them, 89 patients (42.6%) had an insufficient protein intake, and 104 patients (49.8%) had an insufficient energy intake. Additionally, 127 subjects were identified as frail, characterized by being older (61.9 ± 9.5 vs. 55.6 ± 12.8, p < 0.001), malnourished (SGA: 21.0 ± 2.7 vs. 22.7 ± 3.1, p < 0.001), and having a high inflammation burden (MIS: 10.55 ± 3.72 vs. 7.18 ± 3.61, p < 0.001). There was a significant correlation between dietary zinc intake and body mass index (r = 0.31, p < 0.001), SGA (r = 0.22, p = 0.01), and MIS (r = -0.22, p = 0.01). In the multivariate model, a higher dietary zinc intake predicted a higher SGA (beta 0.03, p = 0.003) and lower FQ (beta -0.38, p < 0.001) and MIS (beta -0.14, p < 0.001), indicating a better nutrition, less frail and inflamed state. A higher dietary zinc intake was also associated with a lower odds of being frail (adjusted odds ratio 0.96, p = 0.009).

CONCLUSION

Dietary inadequacy and micronutrient deficiency are common among the PD population. Dietary zinc intake is independently associated with an improved nutrition, physical condition, and reduced inflammatory state.

Does Native Vitamin D Supplementation Have Pleiotropic Effects in Patients with End-Stage Kidney Disease? A Systematic Review of Randomized Trials

Vitamin D has been shown to have multiple pleiotropic effects beyond bone and mineral metabolism, with purported roles in cardiovascular disease, cancer, and host immunity. Vitamin D deficiency is common in patients with end-stage kidney disease (ESKD); however, current clinical practice has favored the use of the active hormone. Whether vitamin D deficiency should be corrected in patients with ESKD remains unclear, as few randomized trials have been conducted. In this systematic review, we summarize the current evidence examining whether vitamin D supplementation improves outcomes, beyond mineral metabolism, in patients with ESKD. Data from randomized controlled trials of adults with ESKD were obtained by searching Ovid MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and the Web of Science Core Collection from inception to February 2023. Twenty-three trials composed of 2489 participants were identified for inclusion. Data were synthesized by two independent reviewers and summarized in tables organized by outcome. Outcomes included measures of mortality, cardiovascular disease, inflammation, muscle strength/function, nutrition, patient well-being, and outcomes specific to ESKD including erythropoietin usage, pruritus, and dialysis access maturation. The Cochrane risk of Bias Tool (RoB 2, 2019) was used to assess study quality. Overall, our findings indicate a minimal and varied benefit of native vitamin D supplementation. From the largest studies included, we determine that vitamin D has no demonstrated effect on patient-reported measures of well-being or utilization of erythropoietin, nor does it change levels of the inflammation biomarker C-reactive protein. Included trials were heterogeneous with regards to outcomes, and the majority studied small participant populations with a relatively short follow-up. We conclude that vitamin D supplementation corrects vitamin D deficiency and is safe and well-tolerated in humans with ESKD. However, it is not clear from clinical trials conducted to date that a causal pathway exists between 25(OH)D and pleiotropic effects that is responsive to vitamin D treatment.

Effects of 25-Hydroxyvitamin D Levels on Renal Function: A Bidirectional Mendelian Randomization Study

CONTEXT

Observational studies investigating the role of vitamin D in renal function have yielded inconsistent results.

OBJECTIVE

We tested whether 25-hydroxyvitamin D (25[OH]D) serum levels are associated with renal function, and inversely, whether altered renal function causes changes in 25(OH)D, using Mendelian randomization (MR).

METHODS

In this two-sample MR study, we used single nucleotide polymorphisms (SNP) associated with 25(OH)D in 443 734 Europeans and evaluated their effects on estimated glomerular filtration rate (eGFR), blood urea nitrogen (BUN), chronic kidney disease (CKD) risk and progression in genome-wide association studies totaling over 1 million Europeans. To control for pleiotropy, we also used SNPs solely in DHCR7, CYP2R1, and GC, all genes with known roles in vitamin D metabolism. We performed a reverse MR, using SNPs for the above indices of renal function to study causal effects on 25(OH)D levels.

RESULTS

We did not find robust evidence supporting effects of 25(OH)D on eGFR, BUN, and CKD or its progression. Our inverse variance weighted MR demonstrated a 0.56 decrease in standardized log-transformed 25(OH)D (95% CI -0.73, -0.41; P = 2.89 × 10-12) per unit increase in log-transformed eGFR. Increased BUN was associated with increased 25(OH)D (β = 0.25, 95% CI 0.15, 0.36; P = 4.12 × 10-6 per unit increase in log-transformed BUN). Finally, genetically predicted CKD conferred a 0.05 increase in standardized log-transformed 25(OH)D level (95% CI 0.04, 0.06; P = 1.06 × 10-13). Other MR methods confirmed the findings of the main analyses.

CONCLUSION

Genetically predicted CKD, increased BUN, and decreased eGFR are associated with increased 25(OH)D levels, but we found no causal effect of 25(OH)D on renal function in Europeans.

The interplay between hypovitaminosis D and the immune dysfunction in the arteriovenous thrombotic complications of the sever coronavirus disease 2019 (COVID-19) infection

Thromboembolic complications including cerebrovascular accidents, pulmonary embolism, myocardial infarction, deep vein thrombosis and disseminating intravascular coagulopathy are serious encounters in sever coronavirus disease 2019 (COVID-19) infected patients. This worsens the prognosis and may lead to death or life long morbidities. The laboratory finding of the disturbed haemostasias and the hyperinflammatory response are almost invariably present in COVID-19 patients. Multiple treatment modalities are utilized by the healthcare professionals to overcome the cytokine storm, oxidative stress, endothelial dysfunction, and coagulopathy in these patients. The combined actions of vitamin D (VitD) as a steroid hormone with anti-inflammatory, immunomodulatory, and antithrombotic properties increase the potential of the possible involvement of hypovitaminosis D in the thromboembolic complications of COVID-19 infection, and stimulated researchers and physicians to administer VitD therapy to prevent the infection and/or overcome the disease complications. The current review highlighted the immunomodulatory, anti-inflammatory, antioxidative and hemostatic functions of VitD and its interrelation with the renin-angiotensin-aldosterone system (RAAS) pathway and the complement system. Additionally, the association of VitD deficiency with the incidence and progression of COVID-19 infection and the associated cytokine storm, oxidative stress, hypercoagulability, and endothelial dysfunction were emphasized. Normalizing VitD levels by daily low dose therapy in patients with hypovitaminosis D below (25 nmol/l) is essential for a balanced immune response and maintaining the health of the pulmonary epithelium. It protects against upper respiratory tract infections and decreases the complications of COVID-19 infections. Understanding the role of VitD and its associated molecules in the protection against the coagulopathy, vasculopathy, inflammation, oxidative stress and endothelial dysfunction in COVID-19 infection could lead to new therapeutic strategies to prevent, treat, and limit the complications of this deadly virus infection.

The Effect of Weekly 50,000 IU Vitamin D3 Supplements on the Serum Levels of Selected Cytokines Involved in Cytokine Storm: A Randomized Clinical Trial in Adults with Vitamin D Deficiency

This research aimed to evaluate the effects of high-dose cholecalciferol (VD₃) supplements (50,000 IU/week) on selected circulating cytokines associated with cytokine storms in adults with vitamin D deficiency. This clinical trial, based in Jordan, included 50 participants receiving vitamin D₃ supplements (50,000 IU/week) for 8 weeks; the exact number was assigned to the control group. Interleukin-6 (IL-6), interleukin-1β (IL-1β), interleukin-10 (IL-10), tumor necrotic factor-α (TNF-α), and leptin were measured in serum at baseline and 10 weeks (wash out: 2 weeks). Our results revealed that vitamin D₃ supplementation significantly increased the serum levels of 25OHD, IL-6, IL-10, IL-1β, and leptin compared with baseline. In contrast, the serum level of TNF-α insignificantly increased in the group receiving vitamin D₃ supplementation. Although the observations of this trial may refer to a potential negative effect of VD₃ supplementation during cytokine storms, further trials are required to clarify the potential benefits of VD₃ supplement during cytokine storms.

Vitamin D and the Kidney: Two Players, One Console

Vitamin D belongs to the group of liposoluble steroids mainly involved in bone metabolism by modulating calcium and phosphorus absorption or reabsorption at various levels, as well as parathyroid hormone production. Recent evidence has shown the extra-bone effects of vitamin D, including glucose homeostasis, cardiovascular protection, and anti-inflammatory and antiproliferative effects. This narrative review provides an overall view of vitamin D’s role in different settings, with a special focus on chronic kidney disease and kidney transplant.

Efficacy of high versus conventional dose of ergocalciferol supplementation on serum 25-hydroxyvitamin D and interleukin-6 levels among hemodialysis patients with vitamin D deficiency: A multicenter, randomized, controlled study

Long-term dialysis involves a chronic inflammatory state and produces a high prevalence of vitamin D deficiency. A clinical trial was conducted in hemodialysis with serum 25-hydroxyvitamin D (25[OH]D) level <30 ng/ml. The conventional-group (N = 35) and the high-dose group (N = 35) were treated with ergocalciferol according to the K/DOQI guidelines and double dosage of ergocalciferol from the recommendation for 8 weeks, respectively. The main outcomes were measured by serum 25[OH]D and interleukin-6 (IL-6). At the end of 8 weeks, a statistically significant greater increase was observed of mean serum 25[OH]D levels and a decrease of mean parathyroid hormone levels in the high-dose group compared with the conventional-dose group. The high dose group had the higher achievement of vitamin D sufficiency than the conventional-dose group (97.4% vs. 76.4%, p = 0.012). No significant difference was found in mean changes of serum IL-6 level in both groups, except subgroup patients with vitamin D deficiency or serum 25[OH]D <20 ng/ml, high dose treatment suppressed serum IL-6 level (-2.67 pg/ml [IQR -6.56 to -0.17], p = 0.039). No differences were observed between the two groups in adverse events. Oral high-dose ergocalciferol supplementation has achieved higher vitamin D sufficiency than standard dose in end stage renal disease patients on dialysis.

Vitamin D Supplementation for Patients with Chronic Kidney Disease: A Systematic Review and Meta-analyses of Trials Investigating the Response to Supplementation and an Overview of Guidelines

A large proportion of patients with chronic kidney disease (CKD) are vitamin D deficient (plasma 25-hydroxyvitamin D (25(OH)D) < 25 or 30 nmol/L per UK and US population guidelines) and this contributes to the development of CKD-mineral bone disease (CKD-MBD). Gaps in the evidence-base for the management of vitamin D status in relation to CKD-MBD are hindering the formulation of comprehensive guidelines. We conducted a systemic review of 22 RCTs with different forms of vitamin D or analogues with CKD-MBD related outcomes and meta-analyses for parathyroid hormone (PTH). We provide a comprehensive overview of current guidelines for the management of vitamin D status for pre-dialysis CKD patients. Vitamin D supplementation had an inconsistent effect on PTH concentrations and meta-analysis showed non- significant reduction (P = 0.08) whereas calcifediol, calcitriol and paricalcitol consistently reduced PTH. An increase in Fibroblast Growth Factor 23 (FGF23) with analogue administration was found in all 3 studies reporting FGF23, but was unaltered in 4 studies with vitamin D or calcifediol. Few RCTS reported markers of bone metabolism and variations in the range of markers prevented direct comparisons. Guidelines for CKD stages G1-G3a follow general population recommendations. For the correction of deficiency general or CKD-specific patient guidelines provide recommendations. Calcitriol or analogues administration is restricted to stages G3b-G5 and depends on patient characteristics. In conclusion, the effect of vitamin D supplementation in CKD patients was inconsistent between studies. Calcifediol and analogues consistently suppressed PTH, but the increase in FGF23 with calcitriol analogues warrants caution.

Implications of oxidative stress in chronic kidney disease: a review on current concepts and therapies

Moderate levels of endogenous reactive oxygen species (ROS) are important for various cellular activities, but high levels lead to toxicity and are associated with various diseases. Levels of ROS are maintained as a balance between oxidants and antioxidants. Accumulating data suggest that oxidative stress is a major factor in deterioration of renal function. In this review, we highlight the possible mechanism by which oxidative stress can lead to chronic kidney disease (CKD). This review also describes therapies that counter the effect of oxidative stress in CKD patients. Numerous factors such as upregulation of genes involved in oxidative phosphorylation and ROS generation, chronic inflammation, vitamin D deficiency, and a compromised antioxidant defense mechanism system cause progressive detrimental effects on renal function that eventually lead to loss of kidney function. Patients with renal dysfunction are highly susceptible to oxidative stress, as risk factors such as diabetes, renal hypertension, dietary restrictions, hemodialysis, and old age predispose them to increased levels of ROS. Biomolecular adducts (DNA, proteins, and lipids) formed due to reaction with ROS can be used to determine oxidative stress levels. Based on the strong correlation between oxidative stress and CKD, reversal of oxidative stress is being explored as a major therapeutic option. Xanthine oxidase inhibitors, dietary antioxidants, and other agents that scavenge free radicals are gaining interest as treatment modalities in CKD patients.

Vitamin D and skeletal muscle: A narrative review focusing on chronic kidney disease and dialysis

Morphological, molecular, and physiological effects of vitamin D on skeletal muscle have been analyzed both in animals and humans. Vitamin D may be a potential therapeutic for increasing muscle mass and function. The presence of vitamin D receptors in skeletal muscle cells is already established. However, there is still need for more evidence about the effect of vitamin D on muscle. Some studies have associated vitamin D and skeletal muscle in chronic kidney disease (CKD) patients; most of these studies enrolled hemodialysis patients. FGF-23 and Klotho were recently described in mineral and bone disorders in CKD, resulting in reductions in calcitriol levels. Therefore, both Klotho and FGF-23 may play a role in muscle loss in CKD, which is related to morbidity and mortality risk. Therefore, this article presents a narrative review, aiming to discuss the available information associating skeletal muscle and vitamin D, highlighting the results in CKD and dialysis patients.

Evidence for possible association of vitamin D status with cytokine storm and unregulated inflammation in COVID-19 patients

OBJECTIVES

We present evidence for a possible role of Vitamin D (VitD) deficiency in unregulated cytokine production and inflammation leading to complications in COVID-19 patients.

DESIGN

The time-adjusted case mortality ratio (T-CMR) was estimated as the ratio of deceased patients on day N to the confirmed cases on day N-8. The adaptive average of T-CMR (A-CMR) was calculated as a metric of COVID-19 associated mortality. A model based on positivity change (PC) and an estimated prevalence of COVID-19 was used to determine countries with similar screening strategies. A possible association of A-CMR with the mean concentration of 25-hydroxyvitamin D (25(OH)D) in elderly individuals in countries with similar screening strategy was investigated. We considered high C-reactive protein (CRP) in severe COVID-19 patients (CRP ≥ 1 mg/dL) as a surrogate of a cytokine storm. We considered high-sensitivity CRP (hs-CRP) in healthy subjects as hs-CRP ≥ 0.2 mg/dL.

RESULTS

A link between 25(OH)D and A-CMR in countries with similar screening strategy is evidence for VitD's possible role in reducing unregulated cytokine production and inflammation among patients with severe COVID-19. We observed an odds ratio (OR) of 1.8 with 95% confidence interval (95% CI) (1.2 to 2.6) and an OR of 1.9 with 95% CI (1.4 to 2.7) for hs-CRP in VitD deficient elderly from low-income families and high-income families, respectively. COVID-19 patient-level data show an OR of 3.4 with 95% CI (2.15 to 5.4) for high CRP in severe COVID-19 patients.

CONCLUSION

We conclude that future studies on VitD's role in reducing cytokine storm and COVID-19 mortality are warranted.

KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for nutrition in kidney diseases since 1999. Since the publication of the first KDOQI nutrition guideline, there has been a great accumulation of new evidence regarding the management of nutritional aspects of kidney disease and sophistication in the guidelines process. The 2020 update to the KDOQI Clinical Practice Guideline for Nutrition in CKD was developed as a joint effort with the Academy of Nutrition and Dietetics (Academy). It provides comprehensive up-to-date information on the understanding and care of patients with chronic kidney disease (CKD), especially in terms of their metabolic and nutritional milieu for the practicing clinician and allied health care workers. The guideline was expanded to include not only patients with end-stage kidney disease or advanced CKD, but also patients with stages 1-5 CKD who are not receiving dialysis and patients with a functional kidney transplant. The updated guideline statements focus on 6 primary areas: nutritional assessment, medical nutrition therapy (MNT), dietary protein and energy intake, nutritional supplementation, micronutrients, and electrolytes. The guidelines primarily cover dietary management rather than all possible nutritional interventions. The evidence data and guideline statements were evaluated using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Associations Between Complement Components and Vitamin D and the Physical Activities of Daily Living Among a Longevous Population in Hainan, China

Background: Vitamin D and complement components shared some common pathophysiological pathways in the musculoskeletal system, circulation, and metabolism, which were linked to physical function. It is hypothesized that serum complement components may interact with vitamin D in respect of the physical activities of daily living (PADLs). Objective: To investigate if serum complement components 3 (C3), complement components 4 (C4), and 25-hydroxyvitamin D [25(OH)D] associate with PADLs, and to examine whether the association between 25(OH)D levels and PADLs varies at different complement component levels among Chinese centenarians. Methods: This study was conducted in a group of population-based centenarians. PADLs were evaluated using the Barthel Index. Multiple regressions were used to analyze the associations among 25(OH)D, complements C3 and C4, and PADLs. Results: Among 943 participants, 672 (71.3%) had physical dependence (PD). After adjusting for potential confounders, serum 25(OH)D and C3 levels were positively correlated with PADLs, while C4 levels were negatively correlated with PADLs (Ps < 0.05). Serum 25(OH)D levels significantly interacted with both C3 (P for interaction = 0.033) and C4 (P for interaction = 0.006) levels on PADLs. At lower complement component levels, the multivariate odds ratios (ORs) of the upper tertile of vitamin D for PD were 0.32 (95% CI: 0.18-0.55) in the C3 group and 0.29 (95% CI: 0.16-0.50) in the C4 group. At higher complement component levels, the ORs in the C3 and C4 groups were not statistically significant. Conclusions: In a group of population-based Chinese centenarians, we observed that serum complement C3 and 25(OH)D levels were positively associated with PADLs, while C4 was negatively associated with PADLs. The associations between 25(OH)D levels and PADLs were more pronounced in groups with lower serum complement component levels.

Role of vitamin D in oxidative stress modulation in end-stage renal disease patients: A double-blind randomized clinical trial

INTRODUCTION

Oxidative stress is considered as important actor in uremia-associated morbidity and mortality in hemodialysis (HD) patients. We aimed to evaluate the role of vitamin D supplementation on oxidative stress parameters in this group.

METHODS

This double-blind randomized clinical trial was conducted on HD patients who were randomly allocated into intervention (n = 40) or control groups (n = 38) for 10 weeks. Blood samples were taken before and at the end of the trial to measure serum 25-hydroxyvitamin D (25(OH)D), malondialdehyde (MDA), glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD). Data were analyzed using SPSS, and P value <0.05 was considered to be statistically significant.

FINDINGS

Out of the 78 patients with a mean age of 44.7 ± 13.0 years, 55.1% were men. At the commencement of the study, there was no difference with respect to serum 25(OH)D levels in our groups (P = 0.575), but during the study it was significantly elevated in the intervention group (18.1 ± 9.1 vs. 31.7 ± 12.9, P < 0.0001). Serum antioxidative enzymes activity (GPx, CAT, and SOD) had significantly increased after vitamin D supplementation in the intervention group (P < 0.05). Furthermore, MDA levels was significantly reduced only in the intervention group (31.7 ± 18.0 vs. 24.7 ± 7.7, P = 0.018).

DISCUSSION

Regular consumption of vitamin D can increase the GPx, CAT, SOD, and reduce the MDA plasma levels in HD patients. Since no adverse effects of vitamin D supplementation was reported by the patients; hence, it can be prescribed for HD patients.

Monocytes in Uremia

Monocytes play an important role in both innate immunity and antigen presentation for specific cellular immune defense. In patients with chronic renal failure, as well as those treated with maintenance hemodialysis, these cells are largely dysregulated. There is a large body of literature on monocyte alterations in such patients. However, most of the publications report on small series, there is a vast spectrum of different methods and the heterogeneity of the data prevents any meta-analytic approach. Thus, a narrative review was performed to describe the current knowledge. Monocytes from patients with chronic renal failure differ from those of healthy individuals in the pattern of surface molecule expression, cytokine and mediator production, and function. If these findings can be summarized at all, they might be subsumed as showing chronic inflammation in resting cells together with limited activation upon immunologic challenge. The picture is complicated by the fact that monocytes fall into morphologically and functionally different populations and population shifts interact heavily with dysregulation of the individual cells. Severe complications of chronic renal failure such as impaired immune defense, inflammation, and atherosclerosis can be related to several aspects of monocyte dysfunction. Therefore, this review aims to provide an overview about the impairment and activation of monocytes by uremia and the resulting clinical consequences for renal failure patients.

Acute Phase Proteins and Vitamin D Seasonal Variation in End-Stage Renal Disease Patients

End-stage renal disease (ESRD) patients are vulnerable to vitamin D deficiency due to impaired renal hydroxylation, low dietary intake and inadequate sun exposure. Vitamin D plays a role in innate and adaptive immunity and its seasonal variation has been linked to mortality. ESRD is associated with inadequate removal of pro-inflammatory cytokines regulating acute phase protein (APP) synthesis. Our aim was to look for associations between lifestyle factors, diet, and vitamin D seasonal variation and their relationship with selected APPs and calcium-phosphate metabolism. The study included 59 ESRD patients treated with maintenance hemodialysis. A 24-hour dietary recall was conducted in the post-summer (November 2018, PS) and post-winter (February/March 2019, PW) period, and blood was collected for the measurements of serum total vitamin D, α1-acid glycoprotein (AGP), C-reactive protein (CRP), albumin, prealbumin (PRE), parathormone, calcium and phosphate. A self-constructed questionnaire gathered information on vitamin D supplementation, sun exposure and physical activity. Higher caloric intake was observed PW compared PS. Less than 15% of participants met the dietary recommendations for energy, protein, fiber, vitamin D and magnesium intake. Vitamin D supplementation was associated with higher serum vitamin D regardless of season. AGP, PRE, albumin, and vitamin D presented seasonal changes (higher values PS). In patients with serum vitamin D below 25 ng/mL, vitamin D seasonal change correlated with CRP and prealbumin change. Phosphate and Ca × P correlated positively with AGP. A low vitamin D serum level could impact the inflammatory process; however, more studies are needed to confirm the relationship.

Vitamin D and obesity in adults: a pathophysiological and clinical update

Vitamin D deficiency has become an increasing focus of clinical interest, especially in understanding its associations with obesity in adults. The pathological associations linking the two appear to demonstrate complex cellular inflammatory, hormonal and genetic pathways. Enhanced understanding at both microcellular and clinical levels will help clarify the role of obesity in the development of vitamin D deficiency.

25-vitamin D reduces inflammation in uremic environment

Chronic kidney disease (CKD) is characterized by loss of renal function and a consequent increase of serum uremic toxins, which contribute to inflammation status. Deficiency of 25-vitamin D, often found in patients with CKD, has been included as an inflammatory factor since it might modulate the immune system. The aim of this study was to investigate the role of 25-vitamin D on inflammatory pathways in healthy and uremic environment. Toll-like receptor 4 (TLR4), oxidative stress (ROS), vitamin D receptor (VDR), 1-α hydroxylase (CYP27), 24 hydroxylase, cathelicidin, and MCP-1 were evaluated in monocytes exposed to a uremic serum pool compared with healthy pool. The human monocytes lineage (U937) was incubated with or without 25-vitamin D (50 ng/ml for 24 hours). TRL4, VDR, CYP27, CYP24, and ROS were evaluated by flow cytometry. We used ELISA to measure IL-6, TNF-α, IL-10, cathelicidin, and MCP-1 in the cell culture supernatant. We observed a higher expression of TRL-4, IL-6, TNF-α, IL-10, cathelicidin and MCP-1 in monocytes incubated with uremic serum when compared with serum from healthy individuals. Supplementation of 25-vitamin D was able to reduce the expression of TRL4, cathelicidin, and MCP-1 in the uremic environment. There was no difference in the expression of VDR, CYP27 and CYP24 intracellular enzymes. This in vitro study showed that the uremic pool activates inflammatory response in monocytes, which was reversed by 25-vitamin D supplementation; this finding suggests that 25-vitamin D has an anti-inflammatory role in the uremic environment.

Vitamin D levels reverberate in monocytes modulation in hemodialysis patients

BACKGROUND

Patients with chronic kidney disease (CKD) have a severe vitamin D deficiency and increasing epidemiological data suggesting that this deficiency may play a role in overall morbidity and mortality associated with CKD. It is known that vitamin D regulates the immune system, however, in dialysis patients this deficiency and the modulation of proinflammatory cells is unclear. Among these, monocytes arouse interest considering they constitutively express vitamin D receptors.

AIM

This study aimed the evaluation of monocytic profile in CKD patients according to vitamin D levels.

METHODS

Patients in hemodialysis (HD) were divided into two groups, regarding vitamin D levels: Group 1, vitamin D <26 ng/ml (n = 15) and Group 2, vitamin D ≥26 ng/ml (n = 18). Whole blood was collected aiming evaluation of (a) monocytic populations through CD14 and CD16 expression, (b) reactive oxygen species (ROS) generation, and (c) apoptosis.

RESULTS

We observed that in Group 1, when compared to Group 2, there was a significant increase in intermediate monocytes (CD14⁺⁺ CD16 ⁺ ; 34.7 ± 31.6 vs. 12.1 ± 6.3; p = 0.006, respectively) and decrease in classical ones (CD14 ⁺⁺ CD16 ^- ; 45.3 ± 31.8 vs. 70.4 ± 25.1; p = 0.017, respectively). There was no difference between groups regarding nonclassical monocytes (CD14 ⁺ CD16 ⁺⁺ ), as well as to apoptosis and to ROS generation.

CONCLUSION

This study suggests that HD patients with lower vitamin D levels might have an intensified inflammatory outline as intermediate monocytes with an inflammatory pattern are increased in this population, when compared with patients with higher levels of vitamin D.

Native Hypovitaminosis D in CKD Patients: From Experimental Evidence to Clinical Practice

Native hypovitaminosis D (n-hVITD) is frequently found from the early stages of chronic kidney disease (CKD) and its prevalence increases with CKD progression. Even if the implications of n-hVITD in chronic kidney disease-mineral bone disorder (CKD-MBD) have been extensively characterized in the literature, there is a lot of debate nowadays about the so called "unconventional effects" of native vitamin D (25(OH)VitD) supplementation in CKD patients. In this review, highlights of the dimension of the problem of n-hVITD in CKD stages 2-5 ND patients will be presented. In addition, it will focus on the "unconventional effects" of 25(OH)VitD supplementation, the clinical impact of n-hVITD and the most significant interventional studies regarding 25(OH)VitD supplementation in CKD stages 2-5 ND.

Cholecalciferol Supplementation Did Not Change Interleukin-7 and B cell-Activating Factor Levels and CD95 Expression in B lymphocytes in Patients on Dialysis: A Randomized Pilot-Controlled Trial

BACKGROUND

End-stage renal disease results in B cell lymphopenia and low levels of vitamin D. Since the link between vitamin D deficiency and B lymphocytes dysfunction are not clear in patients with end-stage renal disease, we suggest that vitamin D adequacy and factors related to the homeostasis of these cells should be investigated. B lymphocytes homeostasis is a process mainly regulated signals of grown and death as interleukin (IL)-7, B cell-activating factor (BAFF)/BAFF-receptor and CD95 expression.

OBJECTIVE

As vitamin D serum levels were reduced in patients with end stage renal disease and it is associated with human B homeostasis, we evaluated the effect of cholecalciferol supplementation on dialysis.

DESIGN

Randomized, double blind clinical trial in dialysis patients with 25OH Vitamin D deficiency for a period of 12 weeks.

MAIN OUTCOME MEASURE

In a pilot study, we investigated the effect of cholecalciferol supplementation (100,000 UI once per week or placebo. In vitro, peripheral blood mononuclear cells isolated by Ficoll-Hypaque centrifugation from 12 healthy volunteers were incubated with healthy or uremic serum in the presence or absence of 25 (OH)DC with 5% CO.

RESULTS

There was an increase in the serum 25(OH)D level in the cholecalciferol group. No differences were found in BAFF and IL7 levels and CD95 and BAFF-R expression in B lymphocytes from patients on dialysis after cholecalciferol supplementation. Uremic serum induced an increase in the IL-7, BAFF, BAFF-R and CD95 expression compared with the control. However, we observed no effect of incubation of 25(OH)D3 and 1,25(OH)2D3 on the expression of IL-7, BAFF, BAFF-R and CD95 when incubated in the presence of normal or uremic serum.

CONCLUSION

Our results suggest that vitamin D is not involved in mechanisms of regulation of differentiation and survival in B lymphocytes. In conclusion, further studies are needed to explore the effects of vitamin D on B lymphocytes to better evaluate the possible impact of vitamin D on humoral response in the CKD population.

Aoike D, Q. Redublo BM, C. Batista M, Cendoroglo M, Maria Moyses R, Dalboni MA. Cholecalciferol decreases inflammation and improves vitamin D regulatory enzymes in lymphocytes in the uremic environment: A randomized controlled pilot trial

It has been reported that vitamin D regulates the immune system. However, whether vitamin D repletion modulates inflammatory responses in lymphocytes from dialysis patients is unclear. In the clinical trial, thirty-two (32) dialysis patients with 25 vitamin D ≤ 20ng/mL were randomized to receive either supplementation of cholecalciferol 100,000 UI/week/3 months (16 patients) or placebo (16 patients). In the in vitro study, B and T lymphocytes from 12 healthy volunteers (HV) were incubated with or without uremic serum in the presence or absence of 25 or 1,25 vitamin D. We evaluated the intracellular expression of IL-6, IFN-γ TLR7, TLR9, VDR, CYP27b1 and CYP24a1 by flow cytometry. We observed a reduction in the expression of TLR7, TLR9, INF-γ and CYP24a1 and an increase in VDR and CYP27b1 expression in patients which were supplemented with cholecalciferol, whereas no differences were found in the placebo group. Uremic serum increased the intracellular expression of IL-6, IFN-γ, TLR7, TLR9, VDR, CYP27b1 and CYP24a1. Treatment with 25 or 1,25 vitamin D decreased IL-6 and TLR9. CYP24a1 silencing plus treatment with 25 and/or 1,25 vitamin D had an additional reduction effect on IL-6, IFN-γ, TLR7 and TLR9 expression. This is the first study showing that cholecalciferol repletion has an anti-inflammatory effect and improves vitamin D intracellular regulatory enzymes on lymphocytes from dialysis patients.

Vitamin D in Chronic Kidney Disease and Dialysis Patients

Vitamin D deficiency (<20 ng/mL) and insufficiency (20–29 ng/mL) are common among patients with chronic kidney disease (CKD) or undergoing dialysis. In addition to nutritional and sunlight exposure deficits, factors that affect vitamin D deficiency include race, sex, age, obesity and impaired vitamin D synthesis and metabolism. Serum 1,25(OH)₂D levels also decrease progressively because of 25(OH)D deficiency, together with impaired availability of 25(OH)D by renal proximal tubular cells, high fibroblast growth factor (FGF)-23 and decreased functional renal tissue. As in the general population, this condition is associated with increased morbidity and poor outcomes. Together with the progressive decline of serum calcitriol, vitamin D deficiency leads to secondary hyperparathyroidism (SHPT) and its complications, tertiary hyperparathyroidism and hypercalcemia, which require surgical parathyroidectomy or calcimimetics. Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease Improving Global Outcomes (KDIGO) experts have recognized that vitamin D insufficiency and deficiency should be avoided in CKD and dialysis patients by using supplementation to prevent SHPT. Many vitamin D supplementation regimens using either ergocalciferol or cholecalciferol daily, weekly or monthly have been reported. The benefit of native vitamin D supplementation remains debatable because observational studies suggest that vitamin D receptor activator (VDRA) use is associated with better outcomes and it is more efficient for decreasing the serum parathormone (PTH) levels. Vitamin D has pleiotropic effects on the immune, cardiovascular and neurological systems and on antineoplastic activity. Extra-renal organs possess the enzymatic capacity to convert 25(OH)D to 1,25(OH)₂D. Despite many unanswered questions, much data support vitamin D use in renal patients. This article emphasizes the role of native vitamin D replacement during all-phases of CKD together with VDRA when SHPT persists.

Secondary Hyperparthyroidism: Pathogenesis, Diagnosis, Preventive and Therapeutic Strategies

Uremic secondary hyperparathyroidism is a multifactorial and complex disease often present in advanced stages of chronic kidney disease. The accumulation of phosphate, the increased FGF23 levels, the reduction in active vitamin D production, and the tendency to hypocalcemia are persistent stimuli for the development and progression of parathyroid hyperplasia with increased secretion of PTH. Parathyroid proliferation may become nodular mainly in cases of advanced hyperparathyroidism. The alterations in the regulation of mineral metabolism, the development of bone disease and extraosseous calcifications are essential components of chronic kidney disease-mineral and bone disorder and have been associated with negative outcomes. The management of hyperparathyroidism includes the correction of vitamin D deficiency and control of serum phosphorus and PTH without inducing hypercalcemia. An update of the leading therapeutic tools available for the prevention and clinical management of secondary hyperparathyroidism, its diagnosis, and the main mechanisms and factors involved in the pathogenesis of the disease will be described in this review.