Influence of Vitamin D on Islet Autoimmunity and Beta-Cell Function in Type 1 Diabetes

Vitamin D Supplementation Modulates ICOS+ and ICOS- Regulatory T Cell in Siblings of Children With Type 1 Diabetes

OBJECTIVES

Vitamin D plays an immunoregulatory activity. The aim of this study was to assess the correlation between blood serum 25(OH)D levels and Th17 and Treg circulating subsets, mainly Treg/inducible costimulatory-positive (ICOS+), which seems to have a protective role in autoimmunity, in children with type 1 diabetes mellitus (T1D) and their healthy siblings (S). The secondary aim was to evaluate the impact of vitamin D supplementation on these subsets.

PATIENTS AND METHODS

22 T1D and 33 S were enrolled. Glucose, hemoglobin A1c, 25 OH vitamin D (25[OH]D), T helper type 17 (Th17; CD4+CCR6+), regulatory T cells (Treg; CD4+CD25+Foxp3+), and Treg/ICOS+ cells were evaluated. According to human leukocyte antigen (HLA) haplotypes, subjects were classified as "at risk" (HLA+), "protective haplotypes" (HLA-; "nested controls"), and "undetermined" (HLAUND). T1D and S subjects were supplemented with cholecalciferol 1000 IU/die and evaluated after 6 months.

RESULTS

Vitamin D insufficiency (74.4%) and deficiency (43%) were frequent. S subjects with 25(OH)D levels <25 nmol/L had Th17, Treg (p < 0.01), and Treg/ICOS+ (P < 0.05) percentages higher than subjects with 25(OH)D >75 nmol/L. Treg/ICOS+ percentages (P < 0.05) were higher in HLA- S subjects compared to percentages observed in S with T1D. At baseline, in S subjects, a decreasing trend in Th17 and Treg/ICOS+ values (P < 0.05) from vitamin D deficiency to sufficiency was observed; 25(OH)D levels were negative predictors of Treg/ICOS+ (R2 = 0.301) and Th17 percentages (R2 = 0.138). After 6 months, supplemented S subjects showed higher 25(OH)D levels (P < 0.0001), and lower Th17 (P < 0.0001) and Treg/ICOS+ (P < 0.05) percentages than at baseline; supplemented T1D patients only had a decrease in Th17 levels (P < 0.05).

CONCLUSION

Serum 25(OH)D levels seem to affect Th17 and Treg cell subsets in S subjects, consistent with its immunomodulating role. HLA role should be investigated in a larger population.

Prevalence of nutritional deficiencies in bariatric surgery candidates and its effect on metabolic status

BACKGROUND

Nutritional deficiencies are common among obese individuals and constitute one of the main concerns in the bariatric field. The aim of this study was to investigate nutritional status in bariatric surgery candidates, comparing individuals with and without metabolic syndrome (MetS) and to explore possible associations between nutritional and metabolic status.

METHODS

Patients accepted for gastric sleeve surgery between 2010 and 2015 were included and anthropometric and metabolic parameters were recorded before surgery. Univariate and multivariate analyses were applied in order to find possible associations between MetS, nutritional, anthropometric, and metabolic parameters.

RESULTS

A total of 330 patients were evaluated (285 females, mean age of 41.88 ± 10.4 years old, mean body mass index 43.91 ± 6.2 kg/m²) and MetS was present in 47% of them. Patients without MetS presented a higher prevalence of folate deficiency (12 vs. 2%, p < 0.001). Male gender, older age, lower magnesium levels, and higher BMI and calcium levels were predictors of a greater number of MetS components. Male gender, a greater number of MetS components, and lower magnesium were predictors of higher homeostatic model assessment for insulin resistance (HOMA-IR).

CONCLUSIONS

The rising prevalence of obesity is causing a parallel increase in the use of bariatric surgery. The high occurrence of preoperative nutritional deficiencies can impair metabolic status and contribute to a worse outcome after surgery. Nutritional assessment and improvement before surgery may be crucial to optimize patient status, and future studies should explore the effect of the correction of these deficiencies in the metabolic status of these patients.

Association of Vitamin D Pathway Gene CYP27B1 and CYP2R1 Polymorphisms with Autoimmune Endocrine Disorders: A Meta-Analysis

BACKGROUND

Studies on organ-specific autoimmune endocrine disorders showed correlations between disease risks and vitamin D pathways gene variants, such as CYP27B1 rs10877012 and rs4646536, or CYP2R1 rs10741657 single nucleotide polymorphisms. However, previous works presented inconsistent conclusions. Our study aimed at assessing the association of CYP27B1 and CYP2R1 polymorphisms with autoimmune endocrine disorder susceptibility using the meta-analysis method.

METHODS

Case-control studies of the subject of interest were identified from the databases Pubmed, Embase, Cochrane Library, and China National Knowledge Infrastructure. Studies that met inclusion and quality criteria were pooled. Observational outcomes were diagnosis of autoimmune Addison's disease, Graves disease, Hashimoto thyroiditis, or type 1 diabetes mellitus. Statistical analysis was performed using software STATA 16.0.

RESULTS

A total of 14 studies involving 12 929 patients (2243 autoimmune Addison disease, 1253 Graves disease, 612 Hashimoto thyroiditis, 8821 type 1 diabetes), and 12 907 healthy control subjects were pooled for meta-analysis. The rs10877012 minor allele A and its homozygote and heterozygote conferred low overall disease risk (OR [odds ratio] = 0.748, 95% CI [confidence interval] 0.620-0.902 in dominant model; OR = 0.709, 95% CI 0.571-0.879 in recessive model; OR = 0.777, 95% CI 0.674-0.895 in the allele model). The population carrying rs4646536 minor allele C and its homozygote and heterozygote showed decreased overall autoimmune endocrine disorders risk (OR = 0.849, 95% CI 0.748-0.963; OR = 0.868, 95% CI 0.790-0.955; OR = 0.915, 95% CI 0.875-0.957 in the dominant, recessive, and allele model, respectively). No significant genetic association was found for rs10741657.

CONCLUSION

Our study suggested CYP27B1 polymorphisms rs10877012 minor allele A and rs4646536 minor allele C were negatively related to susceptibilities of organ-specific autoimmune endocrine diseases.

Role of vitamin D in preventing of COVID-19 infection, progression and severity

The outbreak of COVID-19 has created a global public health crisis. Little is known about the protective factors of this infection. Therefore, preventive health measures that can reduce the risk of infection, progression and severity are desperately needed. This review discussed the possible roles of vitamin D in reducing the risk of COVID-19 and other acute respiratory tract infections and severity. Moreover, this study determined the correlation of vitamin D levels with COVID-19 cases and deaths in 20 European countries as of 20 May 2020. A significant negative correlation (p=0.033) has been observed between mean vitamin D levels and COVID-19 cases per one million population in European countries. However, the correlation of vitamin D with COVID-19 deaths of these countries was not significant. Some retrospective studies demonstrated a correlation between vitamin D status and COVID-19 severity and mortality, while other studies did not find the correlation when confounding variables are adjusted. Several studies demonstrated the role of vitamin D in reducing the risk of acute viral respiratory tract infections and pneumonia. These include direct inhibition with viral replication or with anti-inflammatory or immunomodulatory ways. In the meta-analysis, vitamin D supplementation has been shown as safe and effective against acute respiratory tract infections. Thus, people who are at higher risk of vitamin D deficiency during this global pandemic should consider taking vitamin D supplements to maintain the circulating 25(OH)D in the optimal levels (75-125nmol/L). In conclusion, there is not enough evidence on the association between vitamin D levels and COVID-19 severity and mortality. Therefore, randomized control trials and cohort studies are necessary to test this hypothesis.

Vitamin D Pathway Genetic Variation and Type 1 Diabetes: A Case-Control Association Study

Vitamin D has immunomodulatory effects, and its deficiency has been implicated in the autoimmune process of type 1 diabetes. Serum vitamin D levels are influenced by variants in genes involved in the synthesis, transport, hydroxylation and degradation of vitamin D. The aim of this study was to assess if single nucleotide polymorphisms (SNPs) at the DHCR7 (rs12785878), GC (rs2282679), CYP2R1 (rs2060793) and CYP24A1 (rs6013897) loci are associated with type 1 diabetes in the Portuguese population. Genotype and allele frequencies were determined in 350 cases of type 1 diabetes and in 490 controls. The frequency of each SNP alone was not significantly different between patients and controls. However, the combined analysis of the four SNPs showed that minor alleles of these variants clustered more frequently in patients. The proportion of individuals with three or more minor alleles was significantly higher in patients than in controls (56.3% vs. 48.5; odds ratio (OR) 1.37; 95% confidence interval (CI) 1.04-1.81; p-value 0.027). These results suggest a cumulative effect of SNPs at the DHCR7, GC, CYP2R1 and CYP24A1 loci on the susceptibility to type 1 diabetes, due to the roles of these genes in the vitamin D metabolic pathway.

Enteroviruses and T1D: Is It the Virus, the Genes or Both which Cause T1D

Type 1 diabetes (T1D) is a chronic autoimmune disorder that results from the selective destruction of insulin-producing β-cells in the pancreas. Up to now, the mechanisms triggering the initiation and progression of the disease are, in their complexity, not fully understood and imply the disruption of several tolerance networks. Viral infection is one of the environmental factors triggering diabetes, which is initially based on the observation that the disease’s incidence follows a periodic pattern within the population. Moreover, the strong correlation of genetic susceptibility is a prerequisite for enteroviral infection associated islet autoimmunity. Epidemiological data and clinical findings indicate enteroviral infections, mainly of the coxsackie B virus family, as potential pathogenic mechanisms to trigger the autoimmune reaction towards β-cells, resulting in the boost of inflammation following β-cell destruction and the onset of T1D. This review discusses previously identified virus-associated genetics and pathways of β-cell destruction. Is it the virus itself which leads to β-cell destruction and T1D progression? Or is it genetic, so that the virus may activate auto-immunity and β-cell destruction only in genetically predisposed individuals?

Combined vitamin D, ibuprofen and glutamic acid decarboxylase-alum treatment in recent onset Type I diabetes: lessons from the DIABGAD randomized pilot trial

Aim

Double-blind placebo-controlled intervention using glutamic acid decarboxylase (GAD)-alum, vitamin D and Ibuprofen in recent onset Type I diabetes (T1D).

Methods

64 patients (T1D since <4 months, age 10-17.99, fasting sC-peptide ≥0.12 nmol/l, GADA-positive) were randomized into Day(D) 1-90 400 mg/day Ibuprofen, D1-450 vitamin D 2000 IU/day, D15, 45 sc. 20 μg GAD-alum; as A but placebo instead of Ibuprofen; as B but 40 μg GAD-alum D15, 45; placebo.

Results

Treatment was safe and tolerable. No C-peptide preservation was observed. We observed a linear correlation of baseline C-peptide, HbA1c and insulin/per kilogram/24 h with change in C-peptide AUC at 15 months (r = -0.776, p < 0.0001).

Conclusion

Ibuprofen, vitamin D + GAD-alum did not preserve C-peptide. Treatment efficacy was influenced by baseline clinical and immunological factors and vitamin D concentration. Clinical Trial Registration: NCT01785108 (ClinicalTrials.gov).

Combined vitamin D, ibuprofen and glutamic acid decarboxylase-alum treatment in recent onset Type I diabetes: lessons from the DIABGAD randomized pilot trial

Aim:

Double-blind placebo-controlled intervention using glutamic acid decarboxylase (GAD)-alum, vitamin D and Ibuprofen in recent onset Type I diabetes (T1D).

Methods

64 patients (T1D since <4 months, age 10–17.99, fasting sC-peptide ≥0.12 nmol/l, GADA-positive) were randomized into Day(D) 1–90 400 mg/day Ibuprofen, D1–450 vitamin D 2000 IU/day, D15, 45 sc. 20 μg GAD-alum; as A but placebo instead of Ibuprofen; as B but 40 μg GAD-alum D15, 45; placebo.

Results:

Treatment was safe and tolerable. No C-peptide preservation was observed. We observed a linear correlation of baseline C-peptide, HbA1c and insulin/per kilogram/24 h with change in C-peptide AUC at 15 months (r = -0.776, p < 0.0001).

Conclusion:

Ibuprofen, vitamin D + GAD-alum did not preserve C-peptide. Treatment efficacy was influenced by baseline clinical and immunological factors and vitamin D concentration. Clinical Trial Registration: NCT01785108 (ClinicalTrials.gov).

In many countries, Type I diabetes with insufficient own insulin secretion is a common life-threatening disease in children and adults. There is no prevention and no cure. In spite of very intense treatment, the disease leads to serious complications. There is no efficaceous method to save own insulin secretion without serious risks and adverse events, but autoantigen treatment with glutamic acid decarboxylase has shown some efficacy. We have tried a combination therapy with vitamin D and anti-inflammatory treatment (ibuprofen). Vitamin D in combination with glutamic acid decarboxylase-alum seems to have beneficial effects, but not Ibuprofen. The effect is influenced by basal clinical and immunological status.

Vitamin D effects and endocrine diseases

A lack of vitamin D has been linked to autoimmune diseases including type 1 diabetes, autoimmune thyroiditis and to obesity. The prevalence of vitamin D deficiency is higher in diabetic or obese children and patients with thyroiditis compared to healthy controls. Moreover, low vitamin D values seem to be associated with major complications and poor glycemic control, in particular in obese children. Supplementation with vitamin D, which has immune-regulatory properties, may support our therapies and improve the outcomes in different diseases. Although some studies suggest a possible role of vitamin D in the etiology of autoimmune diseases and obesity, data on supplementation benefits are inconclusive and further studies are needed. In this paper, we focus on the current evidence regarding vitamin D function in endocrine diseases and possible benefits of its supplementation in pediatric age.

Immunomodulatory Effects of Vitamin D in Thyroid Diseases

Vitamin D is a secosteroid with a pleiotropic role in multiple physiological processes. Besides the well-known activity on bone homeostasis, recent studies suggested a peculiar role of vitamin D in different non-skeletal pathways, including a key role in the modulation of immune responses. Recent evidences demonstrated that vitamin D acts on innate and adaptative immunity and seems to exert an immunomodulating action on autoimmune diseases and cancers. Several studies demonstrated a relationship between vitamin D deficiency, autoimmune thyroid disorders, and thyroid cancer. This review aims to summarize the evidences on the immunomodulatory effect of vitamin D on thyroid diseases.

Vitamin D and Immunity in Infants and Children

The last couple of decades have seen an explosion in our interest and understanding of the role of vitamin D in the regulation of immunity. At the molecular level, the hormonal form of vitamin D signals through the nuclear vitamin D receptor (VDR), a ligand-regulated transcription factor. The VDR and vitamin D metabolic enzymes are expressed throughout the innate and adaptive arms of the immune system. The advent of genome-wide approaches to gene expression profiling have led to the identification of numerous VDR-regulated genes implicated in the regulation of innate and adaptive immunity. The molecular data infer that vitamin D signaling should boost innate immunity against pathogens of bacterial or viral origin. Vitamin D signaling also suppresses inflammatory immune responses that underlie autoimmunity and regulate allergic responses. These findings have been bolstered by clinical studies linking vitamin D deficiency to increased rates of infections, autoimmunity, and allergies. Our goals here are to provide an overview of the molecular basis for immune system regulation and to survey the clinical data from pediatric populations, using randomized placebo-controlled trials and meta-analyses where possible, linking vitamin D deficiency to increased rates of infections, autoimmune conditions, and allergies, and addressing the impact of supplementation on these conditions.

The Effects of Vitamin D Supplementation on Lipid and Inflammatory Profile of Healthy Adolescent Boys: A Randomized Controlled Trial

BACKGROUND

Deficiency of vitamin D, an anti-inflammatory micronutrient with some favorable effects on lipid profiles, has been found to be highly prevalent in adolescents. We aimed to investigate the effect of a school-based vitamin D supplementation regimen on the correction of vitamin D deficiency as well as lipid and inflammatory profiles of healthy adolescent boys.

METHODS

In this randomized single-blind placebo-controlled trial, seventy-one healthy adolescent boys (age 17 years old) were recruited from one high school in Tehran, Iran, and randomly assigned to two groups. The supplement group received vitamin D pearls at a dose of 50,000 IU monthly for 6 months, this dose is indeed defined by the Ministry of Health in Iran for a potential national school-based vitamin D supplementation program. The other group was given placebo pearls for the same duration. Before and after the treatment, the serum levels of 25-hydroxy vitamin D (25(OH) D), parathyroid hormone (PTH), retinol, lead (Pb), the lipid profile and the inflammatory biomarkers were measured and compared.

RESULTS

Between-groups statistical analysis showed that a dose (50,000 IU/month) vitamin D significantly increased the serum levels of 25-hydroxyvitamin D (25 (OH) D) (p < 0.001) and decreased serum levels of PTH (p = 0.003). No significant change was observed in serum levels of retinol and Pb. Between-group analysis revealed that the serum levels of TG (P = 0.001) decreased while an increase in serum levels of HDL (p = 0.021) was observed (p < 0.05). Both the within- and between-group analysis showed that serum tumor necrosis factor receptor 2 (TNFR2) concentration declined while serum interleukin-10 (IL-10) increased in response to vitamin D supplementation (p < 0.05).

CONCLUSION

A supplementation regimen of (50,000 IU/month) vitamin D in a context with high rates of vitamin deficiency has shown positive impacts on the serum vitamin D, lipid profile and inflammatory biomarkers in healthy adolescent boys.

Endocrine Disrupting Chemicals and Type 1 Diabetes

Type 1 diabetes (T1D) is the most common chronic metabolic disease in children and adolescents. The etiology of T1D is not fully understood but it seems multifactorial. The genetic background determines the predisposition to develop T1D, while the autoimmune process against β-cells seems to be also determined by environmental triggers, such as endocrine disrupting chemicals (EDCs). Environmental EDCs may act throughout different temporal windows as single chemical agent or as chemical mixtures. They could affect the development and the function of the immune system or of the β-cells function, promoting autoimmunity and increasing the susceptibility to autoimmune attack. Human studies evaluating the potential role of exposure to EDCs on the pathogenesis of T1D are few and demonstrated contradictory results. The aim of this narrative review is to summarize experimental and epidemiological studies on the potential role of exposure to EDCs in the development of T1D. We highlight what we know by animals about EDCs’ effects on mechanisms leading to T1D development and progression. Studies evaluating the EDC levels in patients with T1D were also reported. Moreover, we discussed why further studies are needed and how they should be designed to better understand the causal mechanisms and the next prevention interventions.

Efficacy of Vitamin D3 Buccal Spray Supplementation Compared to Other Delivery Methods: A Systematic Review of Superiority Randomized Controlled Trials

(1) Background: Vitamin D deficiency is an important public health concern and supplementation is common for this deficiency. Many different modes of delivering supplementation have been proposed in order to enhance absorption and utilization. The present review compared the efficacy of vitamin D3 buccal spray against other forms of supplementation delivery. (2) Methods: The protocol was registered at PROSPERO (CRD42019136146). Medline/PubMed, CENTRAL and clinicaltrials.gov were searched from their inception until September 2019, for randomized controlled trials (RCTs) that compare vitamin D3 delivery via sublingual spray against other delivery methods. Eligible RCTs involved humans, of any age and health status, published in any language that evaluated changes in plasma 25(OH)D concentrations. Three reviewers independently extracted data, assessed risk of bias (RoB) and the quality of the trials. (3) Results: Out of 9759 RCTs, four matched the predefined criteria. Intervention duration ranged from 30 days to 3 months whereas vitamin D3 dosage ranged between 800 and 3000 IU/day. One RCT advocated for the superiority of buccal spray in increasing plasma 25(OH)D concentrations, although several limitations were recorded in that trial. The rest failed to report differences in post-intervention 25(OH)D concentrations between delivery methods. Considerable clinical heterogeneity was observed due to study design, intervention duration and dosage, assays and labs used to perform the assays, population age and health status, not allowing for synthesis of the results. (4) Conclusions: Based on the available evidence, delivery of vitamin D3 via buccal spray does not appear superior to the other modes of delivery. Future RCTs avoiding the existing methodological shortcomings are warranted.

Acute Responses to Low and High Intensity Exercise in Type 1 Diabetic Adolescents in Relation to Their Level of Serum 25(OH)D

The main purpose of this study was to investigate the differences in glycaemic reaction in response to various physical activities in 20 young boys (14.4 ± 1.6 years) with type 1 diabetes mellitus (T1DM) and with either vitamin D deficiency or with suboptimal levels of vitamin D. Participants were divided into two groups (deficiency group-DG, n = 10; suboptimal group-SG, n = 10) according to their vitamin D levels. All patients performed aerobic and mixed (aerobic-anaerobic) physical efforts. During the exercise, the respiratory responses and glucose levels were monitored. Biochemical blood analyses were performed before each physical effort. The oxygen consumption was not significantly lower in SG during both aerobic and mixed effort (4.0% and 5.6%, respectively). The glycated haemoglobin (HbA1c) level was higher by 6.1% and the total daily dose of insulin (DDI) was higher by 18.4% in the DG. The differences were not statistically significant. Patients with lower vitamin D levels demonstrated an insignificantly higher glycaemic variability during days with both aerobic and mixed exercises. An appropriate vitamin D concentration in T1DM patients' blood may constitute a prophylactic factor for hyperglycaemia during anaerobic training and hypoglycaemia during aerobic training.

The Role of Vitamin D and Omega-3 PUFAs in Islet Transplantation

Recurrence of autoimmunity and allograft rejection represent major challenges that impact the success of islet transplantation. Despite the remarkable improvements achieved in immunosuppression strategies after the publication of the Edmonton protocol, long-term data of intra-hepatic islet transplantation show a gradual decline in beta-cell function. Therefore, there is a growing interest in the investigation of novel, safe and effective anti-inflammatory and immunomodulatory strategies able to promote long-term islet graft survival and notable improvements in clinical outcomes of islet transplant recipients. Vitamin D has been shown to exert anti-inflammatory and immunomodulatory effects. Pre-clinical studies investigating the use of vitamin D and its analogs (alone or in combination with immunosuppressive agents and/or other anti-inflammatory agents, such as omega-3 polyunsaturated fatty acids) showed beneficial results in terms of islet graft survival and prevention of recurrence of autoimmunity/allograft rejection in animal models of syngeneic and allogeneic islet transplantation. Moreover, epidemiologic studies demonstrated that vitamin D deficiency is highly prevalent after solid organ transplantation (e.g., heart, liver or kidney transplantation). However, studies that critically assess the prevalence of vitamin D deficiency among islet transplant recipients have yet to be conducted. In addition, prospective studies aimed to address the safety and efficacy of vitamin D supplementation as an adjuvant immunomodulatory strategy in islet transplant recipients are lacking and are therefore awaited in the future.

Gastrointestinal Microbiota and Type 1 Diabetes Mellitus: The State of Art

The incidence of autoimmune type 1 diabetes (T1DM) is increasing worldwide and disease onset tends to occur at a younger age. Unfortunately, clinical trials aiming to detect predictive factors of disease, in individuals with a high risk of T1DM, reported negative results. Hence, actually there are no tools or strategies to prevent T1DM onset. The importance of the gut microbiome in autoimmune diseases is increasingly recognized and recent data suggest that intestinal dysbiosis has a pathogenic role in T1DM by affecting both intestinal immunostasis and the permeability of the gut barrier. An improved understanding of the mechanisms whereby dysbiosis in the gut favors T1DM development may help develop new intervention strategies to reduce both the incidence and burden of T1DM. This review summarizes available data on the associations between gut microbiota and T1DM in both experimental animals and humans and discusses future perspectives in this novel and exciting area of research.