Vitamin D supplementation alleviates insulin resistance in prediabetic rats by modifying IRS-1 and PPARγ/NF-κB expressions

Putative mechanism of a multivitamin treatment against insulin resistance

Insulin resistance is caused by the abnormal secretion of proinflammatory cytokines in adipose tissue, which is induced by an increase in lipid accumulation in adipocytes, hepatocytes, and myocytes. The inflammatory pathway involves multiple targets such as nuclear factor kappa B, inhibitor of nuclear factor κ-B kinase, and mitogen-activated protein kinase. Vitamins are micronutrients with anti-inflammatory activities that have unclear mechanisms. The present study aimed to describe the putative mechanisms of vitamins involved in the inflammatory pathway of insulin resistance. The strategy to achieve this goal was to integrate data mining and analysis, target prediction, and molecular docking simulation calculations to support our hypotheses. Our results suggest that the multitarget activity of vitamins A, B1, B2, B3, B5, B6, B7, B12, C, D3, and E inhibits nuclear factor kappa B and mitogen-activated protein kinase, in addition to vitamins A and B12 against inhibitor of nuclear factor κ-B kinase. The findings of this study highlight the pharmacological potential of using an anti-inflammatory and multitarget treatment based on vitamins and open new perspectives to evaluate the inhibitory activity of vitamins against nuclear factor kappa B, mitogen-activated protein kinase, and inhibitor of nuclear factor κ-B kinase in an insulin-resistant context.

Vitamin D3 improves glucose metabolism and attenuates inflammation in prediabetic human and mice

Prediabetes is a crucial stage for prevention and treatment of diabetes, and vitamin D (VD) has been found to be linked to the development of prediabetes and diabetes. Thus, we aimed to identify the effect of VD supplementation on glucose metabolism in prediabetic participants and mice. A 1:1 paired design of randomized, placebo-controlled trial with 1600 IU/day VD3 or placebo was administered to individuals with prediabetes, two-way repeated-measures ANCOVA was used to analyze glycolipid and inflammatory factors. A high-fat diet induced prediabetic KKay mice were utilized to evaluate the effects of VD3 with 16 weeks supplementation. Generalized estimation equation, one way ANOVA were used to analyze continuous monitoring indexes and terminal indexes, respectively. Exercise capacity, skeletal muscle pathological features and relevant proteins were examined. The clinical results showed that VD3 could improve insulin secretion and decrease inflammation. Results of KKay mice exhibited that VD3 not only ameliorate glycolipid metabolism and inflammatory indicators, but also regulated pathological changes of skeletal muscle and exercise capacity. Mechanistically, our results demonstrated that VD3 could inhibit the TLR4/NFκB and activate PI3K/AKT signaling pathway. Collectively, the study indicated that VD3 exerts its beneficial effects by inhibiting TLR4/NFκB to decrease inflammatory response, and activating PI3K/AKT signaling pathway to regulate glucose homeostasis.

Functional foods lipids: unraveling their role in the immune response in obesity

Functional lipids are lipids that are found in food matrices and play an important role in influencing human health as their role goes beyond energy storage and structural components. Ongoing research into functional lipids has highlighted their potential to modulate immune responses and other mechanisms associated with obesity, along with its comorbidities. These lipids represent a new field that may offer new therapeutic and preventive strategies for these diseases by understanding their contribution to health. In this review, we discussed in-depth the potential food sources of functional lipids and their reported potential benefit of the major lipid classification: based on their composition such as simple, compound, and derived lipids, and based on their function such as storage and structural, by investigating the intricate mechanisms through which these lipids interact in the human body. We summarize the key insights into the bioaccessibility and bioavailability of the most studied functional lipids. Furthermore, we review the main immunomodulatory mechanisms reported in the literature in the past years. Finally, we discuss the perspectives and challenges faced in the food industry related to functional lipids.

Associations between Vitamin D Levels and Insulin Resistance in Non-Diabetic Obesity: Results from NHANES 2001-2018

OBJECTIVE

Obesity is often accompanied by insulin resistance (IR) and diabetes. We explored the association between vitamin D levels and IR in non-diabetic obesity.

METHODS

We conducted a cross-sectional study based on the data of National Health and Nutrition Examination Survey (NHANES) from 2001 to 2018. Non-diabetic individuals (aged ≥20 years) with obesity (BMI ≥ 30kg/m2) were included in the study. And HOMA-IR ≥ 2.5 was defined as IR. The multivariable linear regression models were constructed to evaluate the associations between levels of 25(OH)D and HOMA-IR. We calculated the odds ratio (OR) and 95% confidential intervals (CIs) for associations between 25(OH)D deficiency and IR in obesity using multivariable logistic regression models.

RESULTS

Overall, a total of 3887 individuals were included in this study. Serum vitamin D level was significant lower in obesity participants with IR than that of non-IRs. The linear regression models showed that vitamin D level was inversely associated with HOMA-IR in obesity after adjusting for covariables (β=-0.15, 95%CI (-0.28, -0.02), p = 0.028). And the multivariable logistic regression models indicated an association between vitamin D deficiency and IR in obesity ((OR= 1.38, 95%CI (1.09-1.73), p = 0.007)). The further stratified regression analyses among different BMI demonstrated that vitamin D deficiency (OR = 1.4, 95%CI (1.05,1.86), p = 0.022) only contributed to developing IR in class I obesity.

CONCLUSION

This study suggested an association of vitamin D levels with IR in obesity. And vitamin D deficiency contributed to IR in class I obesity.

Effects of maternal advanced lipoxidation end products diet on the glycolipid metabolism and gut microbiota in offspring mice

Introduction

Dietary advanced lipoxidation end products (ALEs), which are abundant in heat-processed foods, could induce lipid metabolism disorders. However, limited studies have examined the relationship between maternal ALEs diet and offspring health.

Methods

To investigate the transgenerational effects of ALEs, a cross-generation mouse model was developed. The C57BL/6J mice were fed with dietary ALEs during preconception, pregnancy and lactation. Then, the changes of glycolipid metabolism and gut microbiota of the offspring mice were analyzed.

Results

Maternal ALEs diet not only affected the metabolic homeostasis of dams, but also induced hepatic glycolipid accumulation, abnormal liver function, and disturbance of metabolism parameters in offspring. Furthermore, maternal ALEs diet significantly upregulated the expression of TLR4, TRIF and TNF-α proteins through the AMPK/mTOR/PPARα signaling pathway, leading to dysfunctional glycolipid metabolism in offspring. In addition, 16S rRNA analysis showed that maternal ALEs diet was capable of altered microbiota composition of offspring, and increased the Firmicutes/Bacteroidetes ratio.

Discussion

This study has for the first time demonstrated the transgenerational effects of maternal ALEs diet on the glycolipid metabolism and gut microbiota in offspring mice, and may help to better understand the adverse effects of dietary ALEs.

Synergistic Effects of Vitamin D and Exercise on Diabetes-induced Gonadotoxicity in Male Wistar Rats: Role of Xanthine Oxidase/Uric Acid and Nrf2/NfkB Signaling

Type 2 Diabetes mellitus (T2DM) is one of the oldest known chronic diseases, characterized by elevated fasting blood sugar (FBS). T2DM is a metabolic disorder that can distort the activities of multiple physiological systems, including the reproductive system. Although different drugs have been designed for managing this disorder, these drugs have been reported to have negative side effects. Hence, this study was designed to explore the possible synergistic effect of vitamin D and exercise on T2DM-induced testicular dysfunction. Thirty-six male Wistar rats were randomized into six (6) groups: control, diabetes untreated, diabetes treated with 1000 IU/kg of vitamin D, diabetes treated with 5 min/day of physical exercise, diabetes treated with vitamin D and exercise, diabetes treated with 180 mg/kg of metformin. T2DM induction led to a significant increase in FBS, lactate, and lactate dehydrogenase, and was reversed by vitamin D supplementation and exercise. Also, vitamin D and exercise synergistically blunted T2DM-induced oxido-inflammatory response evidenced by a significant decrease in testicular malondialdehyde, interleukin 1β, interleukin 6, and tumor necrosis factor alpha, and an increase in superoxide dismutase, catalase, glutathione peroxidase, and interleukin 10. These events were associated with a decrease in T2DM-induced increase in XO, UA, and Nf-κb and an increase in T2DM-induced decrease in Nrf2. Also, vitamin D and EX reversed the observed impairment in sperm quality and testicular histology following T2DM-induction. This study revealed the synergistic effect of vitamin D and exercise on T2DM-induced testicular dysfunction.

Gastrodin ameliorates neuroinflammation in Alzheimer's disease mice by inhibiting NF-κB signaling activation via PPARγ stimulation

AIM

We investigated the effects and targets of gastrodin (GAS) for improving cognitive ability in Alzheimer's disease (AD).

METHODS

The targets and mechanisms of GAS were analyzed by network pharmacology. Morris water and eight-arm radial mazes were used to detect the behaviors of 7-months-old APP/PS1 mice. The levels of IBA-1 and PPARγ were examined by histochemical staining, nerve cells were detected by Nissl staining, inflammatory cytokines were measured by ELISA, and protein expressions were monitored by Western blotting. The neurobehavioral effects of GAS on mice were detected after siRNA silencing of PPARγ. Microglia were cultured in vitro and Aβ1-42 was used to simulate the pathology of AD. After treatment with GAS, the levels of inflammatory cytokines and proteins were assayed.

RESULTS

Network pharmacological analysis revealed that PPARγ was the action target of GAS. By stimulating PPARγ, GAS inhibited NF-κB signaling activation and decreased neuroinflammation and microglial activation, thereby ameliorating the cognitive ability of AD mice. After silencing PPARγ, GAS could not further improve such cognitive ability. Cellular-level results demonstrated that GAS inhibited microglial injury, reduced tissue inflammation, and activated PPARγ.

CONCLUSIONS

GAS can regulate microglia-mediated inflammatory response by stimulating PPARγ and inhibiting NF-κB activation, representing a mechanism whereby it improves the cognitive behavior of AD.

Relationship between Circulating 25-Hydroxyvitamin D and Metabolic Syndrome in Chinese Adults: A Large Nationwide Longitudinal Study

OBJECTIVE

This study investigated the association of circulating levels of 25-hydroxyvitamin D (25[OH]D) with the risk of metabolic syndrome (MetS) and its components in adults.

METHODS

This nationwide cohort involved 23,810 Chinese adults attending annual health evaluations. Serum 25(OH)D levels, MetS status, and covariates were determined at each examination. Among them, 8146, 3310, and 1971 completed two, three, and more than three evaluations, respectively. A hybrid mixed-effects and Cox regression model was employed to determine the cross-sectional and longitudinal relationships.

RESULTS

The odds ratios (ORs) and 95% confidence intervals (CIs) of MetS were significantly lower in individuals within quartile 4 (vs. 1) of serum 25(OH)D for both between-individual (0.43 [0.35, 0.52]) and within-individual comparisons (0.60 [0.50, 0.73]), respectively (all p-trends < 0.001). Among the MetS components, the corresponding ORs (95% CI) in between- and within-individual comparisons were 0.40 (0.29, 0.54) and 0.26 (0.19, 0.36) for abdominal obesity, 0.49 (0.41, 0.58) and 0.78 (0.66, 0.93) for high triglycerides, 0.70 (0.59, 0.82) and 0.75 (0.64, 0.87) for hypertriglyceridemia, 0.48 (0.39, 0.59) and 0.87 (0.71, 1.07) for low HDL cholesterol, and 0.92 (0.76, 1.12) and 0.49 (0.41, 0.59) for hypertension, respectively. Decreased hazard ratios (95% CIs) in quartile 4 (vs. 1) of 25(OH)D were found for MetS (0.80 [0.65, 1.00]), high triglycerides (0.76 [0.62, 0.92]), abdominal obesity (0.77 [0.63, 0.96]), and low HDL cholesterol (0.64 [0.50, 0.81]).

CONCLUSIONS

Decreased concentrations of serum 25(OH)D correlate significantly to a heightened MetS risk and specific components. Our findings underscore the potential preventive function of circulating vitamin D concerning metabolic disorders.

Exploring the Interplay between Vitamin D, Insulin Resistance, Obesity and Skeletal Health

Vitamin D (ViD), plays an important role in calcium absorption and bone mineralization, is associated with bone mineral density. Severe deficiency in ViD has long been linked to conditions such as rickets in children and osteomalacia in adults, revealing its substantial role in skeletal health. Additionally, investigations show an existing interconnection between ViD and insulin resistance (Ins-R), especially in patients with type 2 diabetes mellitus (T2DM). Obesity, in conjunction with Ins-R, may augment the risk of osteoporosis and deterioration of skeletal health. This review aims to examine recent studies on the interplay between ViD, Ins-R, obesity, and their impact on skeletal health, to offer insights into potential therapeutic strategies. Cochrane Library, Google Scholar, and Pubmed were searched to investigate relevant studies until December 2023. Current research demonstrates ViD's impact on pancreatic β-cell function, systemic inflammation, and insulin action regulation. Our findings highlight an intricate association between ViD, Ins-R, obesity, and skeletal health, providing a perspective for the prevention and/or treatment of skeletal disorders in patients with obesity, Ins-R, and T2DM.

Vitamin D loaded into lipid nanoparticles shows insulinotropic effect in INS-1E cells

Increasing evidence suggests a beneficial role of vitamin D (VitD) supplementation in addressing the widespread VitD deficiency, but currently used VitD3 formulations present low bioavailability and toxicity constrains. Hence, poly(L-lactide-co-glycolide) (PLGA) nanoparticles (NPs), solid-lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were investigated to circumvent these issues. PLGA NPs prepared by emulsification or nanoprecipitation presented 74 or 200 nm, and association efficiency (AE) of 68 % and 17 %, respectively, and a rapid burst release of VitD3. Both SLN and NLCs presented higher polydispersity and larger NPs size, around 500 nm, which could be reduced to around 200 nm by use of hot high-pressure homogenization in the case of NLCs. VitD3 was efficiently loaded in both SLNs and NLCs with an AE of 82 and 99 %, respectively. While SLNs showed burst release, NLCs allowed a sustained release of VitD3 for nearly one month. Furthermore, NLCs showed high stability with maintenance of VitD3 loading for up to one month at 4 °C and no cytotoxic effects on INS-1E cells up to 72 h. A trending increase (around 30 %) on glucose-dependent insulin secretion was observed by INS-1E cells pre-treated with VitD3. This effect was consistently observed in the free form and after loading on NLCs. Overall, this work contributed to further elucidation on a suitable delivery system for VitD3 and on the effects of this metabolite on β cell function.

The impact of vitamin D on the etiopathogenesis and the progression of type 1 and type 2 diabetes in children and adults

Diabetes is a common chronic metabolic disease with complex causes and pathogenesis. As an immunomodulator, vitamin D has recently become a research hotspot in the occurrence and development of diabetes and its complications. Many studies have shown that vitamin D can reduce the occurrence of diabetes and delay the progression of diabetes complications, and vitamin D can reduce oxidative stress, inhibit iron apoptosis, promote Ca2+ influx, promote insulin secretion, and reduce insulin resistance. Therefore, the prevention and correction of vitamin D deficiency is very necessary for diabetic patients, but further research is needed to confirm what serum levels of vitamin D3 are maintained in the body. This article provides a brief review of the relationship between vitamin D and diabetes, including its acute and chronic complications.

Environmental Temperature, Other Climatic Variables, and Cardiometabolic Profile in Acute Myocardial Infarction

Objectives: To evaluate CV profiles, periprocedural complications, and in-hospital mortality in acute myocardial infarction (AMI) according to climate. Methods: Data from 2478 AMI patients (1779 men; mean age 67 ∓ 13 years; Pasquinucci Hospital ICU, Massa, Italy; 2007-2018) were retrospectively analyzed according to climate (LAMMA Consortium; Firenze, Italy) by using three approaches as follows: (1) annual warm (May-October) and cold (November-April) periods; (2) warm and cold extremes of the two periods; and (3) warm and cold extremes for each month of the two periods. Results: All approaches highlighted a higher percentage of AMI hospitalization for patients with adverse CV profiles in relation to low temperatures, or higher periprocedural complications and in-hospital deaths. In warmer times of the cold periods, there were fewer admissions of dyslipidemic patients. During warm periods, progressive heat anomalies were characterized by more smoker (approaches 2 and 3) and young AMI patient (approach 3) admissions, whereas cooler times (approach 3) evidenced a reduced hospitalization of diabetic and dyslipidemic patients. No significant effects were observed for the heat index and light circulation. Conclusions: Although largely overlapping, different approaches identify patient subgroups with different CV risk factors at higher AMI admission risk and adverse short-term outcomes. These data retain potential implications regarding pathophysiological mechanisms of AMI and its prevention.

Glucose Fluctuation Inhibits Nrf2 Signaling Pathway in Hippocampal Tissues and Exacerbates Cognitive Impairment in Streptozotocin-Induced Diabetic Rats

Background

This research investigated whether glucose fluctuation (GF) can exacerbate cognitive impairment in streptozotocin-induced diabetic rats and explored the related mechanism.

Methods

After 4 weeks of feeding with diets containing high fats plus sugar, the rat model of diabetes mellitus (DM) was established by intraperitoneal injection of streptozotocin (STZ). Then, GF was triggered by means of alternating satiety and starvation for 24 h. The weight, blood glucose level, and water intake of the rats were recorded. The Morris water maze (MWM) test was carried out to appraise the cognitive function at the end of week 12. Moreover, the morphological structure of hippocampal neurons was viewed through HE and Nissl staining, and transmission electron microscopy (TEM) was performed for ultrastructure observation. The protein expression levels of Nrf2, HO-1, NQO-1, Bax, Bcl-2, and Caspase-3 in the hippocampal tissues of rats were measured via Western blotting, and the mRNA expressions of Nrf2, HO-1, and NQO-1 were examined using qRT-PCR. Finally, Western blotting and immunohistochemistry were conducted to detect BDNF levels.

Results

It was manifested that GF not only aggravated the impairment of spatial memory in rats with STZ-induced type 2 DM but also stimulated the loss, shrinkage, and apoptosis of hippocampal neurons. Regarding the expressions in murine hippocampal tissues, GF depressed Nrf2, HO-1, NQO-1, Bcl-2, and BDNF but boosted Caspase-3 and Bax.

Conclusions

GF aggravates cognitive impairment by inhibiting the Nrf2 signaling pathway and inducing oxidative stress and apoptosis in the hippocampal tissues.