Active form of vitamin D ameliorates non-alcoholic fatty liver disease by alleviating oxidative stress in a high-fat diet rat model

Metabolic dysfunction-associated steatotic liver disease-induced changes in the antioxidant system: a review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a heterogeneous condition characterized by liver steatosis, inflammation, consequent fibrosis, and cirrhosis. Chronic impairment of lipid metabolism is closely related to oxidative stress, leading to cellular lipotoxicity, mitochondrial dysfunction, and endoplasmic reticulum stress. The detrimental effect of oxidative stress is usually accompanied by changes in antioxidant defense mechanisms, with the alterations in antioxidant enzymes expression/activities during MASLD development and progression reported in many clinical and experimental studies. This review will provide a comprehensive overview of the present research on MASLD-induced changes in the catalytic activity and expression of the main antioxidant enzymes (superoxide dismutases, catalase, glutathione peroxidases, glutathione S-transferases, glutathione reductase, NAD(P)H:quinone oxidoreductase) and in the level of non-enzymatic antioxidant glutathione. Furthermore, an overview of the therapeutic effects of vitamin E on antioxidant enzymes during the progression of MASLD will be presented. Generally, at the beginning of MASLD development, the expression/activity of antioxidant enzymes usually increases to protect organisms against the increased production of reactive oxygen species. However, in advanced stage of MASLD, the expression/activity of several antioxidants generally decreases due to damage to hepatic and extrahepatic cells, which further exacerbates the damage. Although the results obtained in patients, in various experimental animal or cell models have been inconsistent, taken together the importance of antioxidant enzymes in MASLD development and progression has been clearly shown.

Hepatocyte vitamin D receptor functions as a nutrient sensor that regulates energy storage and tissue growth in zebrafish

Vitamin D receptor (VDR) has been implicated in fatty liver pathogenesis, but its role in the regulation of organismal energy usage remains unclear. Here, we illuminate the evolutionary function of VDR by demonstrating that zebrafish Vdr coordinates hepatic and organismal energy homeostasis through antagonistic regulation of nutrient storage and tissue growth. Hepatocyte-specific Vdr impairment increases hepatic lipid storage, partially through acsl4a induction, while simultaneously diminishing fatty acid oxidation and liver growth. Importantly, Vdr impairment exacerbates the starvation-induced hepatic storage of systemic fatty acids, indicating that loss of Vdr signaling elicits hepatocellular energy deficiency. Strikingly, hepatocyte Vdr impairment diminishes diet-induced systemic growth while increasing hepatic and visceral fat in adult fish, revealing that hepatic Vdr signaling is required for complete adaptation to food availability. These data establish hepatocyte Vdr as a regulator of organismal energy expenditure and define an evolutionary function for VDR as a transcriptional effector of environmental nutrient supply.

Oxidative Stress as a Target for Non-Pharmacological Intervention in MAFLD: Could There Be a Role for EVOO?

Oxidative stress plays a central role in most chronic liver diseases and, in particular, in metabolic dysfunction-associated fatty liver disease (MAFLD), the new definition of an old condition known as non-alcoholic fatty liver disease (NAFLD). The mechanisms leading to hepatocellular fat accumulation in genetically predisposed individuals who adopt a sedentary lifestyle and consume an obesogenic diet progress through mitochondrial and endoplasmic reticulum dysfunction, which amplifies reactive oxygen species (ROS) production, lipid peroxidation, malondialdehyde (MDA) formation, and influence the release of chronic inflammation and liver damage biomarkers, such as pro-inflammatory cytokines. This close pathogenetic link has been a key stimulus in the search for therapeutic approaches targeting oxidative stress to treat steatosis, and a number of clinical trials have been conducted to date on subjects with NAFLD using drugs as well as supplements or nutraceutical products. Vitamin E, Vitamin D, and Silybin are the most studied substances, but several non-pharmacological approaches have also been explored, especially lifestyle and diet modifications. Among the dietary approaches, the Mediterranean Diet (MD) seems to be the most reliable for affecting liver steatosis, probably with the added value of the presence of extra virgin olive oil (EVOO), a healthy food with a high content of monounsaturated fatty acids, especially oleic acid, and variable concentrations of phenols (oleocanthal) and phenolic alcohols, such as hydroxytyrosol (HT) and tyrosol (Tyr). In this review, we focus on non-pharmacological interventions in MAFLD treatment that target oxidative stress and, in particular, on the role of EVOO as one of the main antioxidant components of the MD.

Vitamin D and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Novel Mechanistic Insights

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an increasingly prevalent condition characterized by abnormal fat accumulation in the liver, often associated with metabolic disorders. Emerging evidence suggests a potential link between vitamin D deficiency and the development and progression of MASLD. The current review provides a concise overview of recent studies uncovering novel mechanistic insights into the interplay between vitamin D and MASLD. Several epidemiological studies have highlighted a significant association between low vitamin D levels and an increased risk of MASLD. Vitamin D, traditionally known for its role in bone health, has now been recognized as a key player in various physiological processes, including immune regulation and inflammation. Experimental studies using animal models have demonstrated that vitamin D deficiency exacerbates liver steatosis and inflammation, suggesting a potential protective role against MASLD. Mechanistically, vitamin D appears to modulate MASLD through multiple pathways. Firstly, the vitamin D receptor (VDR) is abundantly expressed in liver cells, indicating a direct regulatory role in hepatic function. Activation of the VDR has been shown to suppress hepatic lipid accumulation and inflammation, providing a mechanistic basis for the observed protective effects. Additionally, vitamin D influences insulin sensitivity, a critical factor in MASLD pathogenesis. Improved insulin sensitivity may mitigate the excessive accumulation of fat in the liver, thus attenuating MASLD progression. In parallel, vitamin D exhibits anti-inflammatory properties by inhibiting pro-inflammatory cytokines implicated in MASLD pathophysiology. Experimental evidence suggests that the immunomodulatory effects of vitamin D extend to the liver, reducing inflammation and oxidative stress, key drivers of MASLD, and the likelihood of hepatocyte injury and fibrosis. Understanding the complex interplay between vitamin D and MASLD provides a basis for exploring targeted therapeutic strategies and preventive interventions. As vitamin D deficiency is a modifiable risk factor, addressing this nutritional concern may prove beneficial in mitigating the burden of MASLD and associated metabolic disorders.

Mitochondrial Dysfunction in Metabolic Dysfunction Fatty Liver Disease (MAFLD)

Nonalcoholic fatty liver disease (NAFLD) has become an increasingly common disease in Western countries and has become the major cause of liver cirrhosis or hepatocellular carcinoma (HCC) in addition to viral hepatitis in recent decades. Furthermore, studies have shown that NAFLD is inextricably linked to the development of extrahepatic diseases. However, there is currently no effective treatment to cure NAFLD. In addition, in 2020, NAFLD was renamed metabolic dysfunction fatty liver disease (MAFLD) to show that its pathogenesis is closely related to metabolic disorders. Recent studies have reported that the development of MAFLD is inextricably associated with mitochondrial dysfunction in hepatocytes and hepatic stellate cells (HSCs). Simultaneously, mitochondrial stress caused by structural and functional disorders stimulates the occurrence and accumulation of fat and lipo-toxicity in hepatocytes and HSCs. In addition, the interaction between mitochondrial dysfunction and the liver-gut axis has also become a new point during the development of MAFLD. In this review, we summarize the effects of several potential treatment strategies for MAFLD, including antioxidants, reagents, and intestinal microorganisms and metabolites.

Insights into the role of vitamin D in targeting the culprits of non-alcoholic fatty liver disease

Vitamin D (VD) is a secosteroid hormone that is renowned for its crucial role in phospho-calcium homeostasis upon binding to the nuclear vitamin D receptor (VDR). Over and above, the pleiotropic immunomodulatory, anti-inflammatory, and metabolic roles VD plays in different disease settings started to surface in the past few decades. On the other hand, a growing body of evidence suggests a correlation between non-alcoholic fatty liver disease (NAFLD) and its progressive inflammatory form non-alcoholic steatohepatitis (NASH) with vitamin D deficiency (VDD) owing to the former's ingrained link with obesity and metabolic syndrome. Accordingly, a better understanding of the contribution of disrupted VDR signalling to NAFLD incidence and progression would provide further insights into its diagnosis, treatment modalities, and prognosis. This is especially significant as, hitherto, no drug for NAFLD has been approved. This review, therefore, sought to set forth the likely contribution of VDR signalling in NAFLD and how it might influence its multiple drivers.

Vitamin D3 alleviates nonalcoholic fatty liver disease in rats by inhibiting hepatic oxidative stress and inflammation via the SREBP-1-c/ PPARα-NF-κB/IR-S2 signaling pathway

Introduction: Nonalcoholic fatty liver disease (NAFLD) is a chronic disease characterized by fat deposits in liver cells, which can lead to hepatitis and fibrosis. This study attempted to explore the protective effect of vitamin D3 (VitD) against NAFLD. Methods: Adult male albino rats were randomized into four separate groups: the negative control group was fed a standard rat chow; the positive group received a high-fat diet (20%) and 25% fructose water (NAFLD); the VitD control group was intramuscularly treated with VitD (1,000 IU/kg BW) 3 days per week for 10 weeks; and the NAFLD group was treated with VitD therapy. Biochemical and hepatic histological analyses were performed. Hepatic oxidative stress and inflammatory conditions were also studied. Hepatic expression of sterol regulatory element-binding protein 1-c (SREBP-1-c), peroxisome proliferator-activated receptor alpha (PPAR-α), and insulin receptor substrate-2 was analyzed by quantitative real-time polymerase chain reaction. Results and discussion: The NAFLD rats exhibited elevated terminal body weight, hepatic injury markers, dyslipidemia, glucose intolerance, and insulin resistance. Moreover, the NAFLD rats had increased SREBP-1-c expression and reduced PPAR-α and IRS-2 expressions. Histological analysis showed hepatic steatosis and inflammation in the NAFLD group. In contrast, VitD administration improved the serum biochemical parameters and hepatic redox status in NAFLD rats. Also, VitD treatment ameliorated hepatic inflammation and steatosis in the NAFLD group by decreasing the expression of SREBP-1-c and increasing the expression of PPAR-α. Overall, these results suggest that VitD could have a protective effect against NAFLD and its associated complication.

Non-Alcoholic Fatty Liver Disease and Bone Tissue Metabolism: Current Findings and Future Perspectives

Non-alcoholic fatty liver disease (NAFLD) is reaching epidemic proportions worldwide. Moreover, the prevalence of this liver disease is expected to increase rapidly in the near future, aligning with the rise in obesity and the aging of the population. The pathogenesis of NAFLD is considered to be complex and to include the interaction between genetic, metabolic, inflammatory, and environmental factors. It is now well documented that NAFLD is linked to the other conditions common to insulin resistance, such as abnormal lipid levels, metabolic syndrome, and type 2 diabetes mellitus. Additionally, it is considered that the insulin resistance may be one of the main mechanisms determining the disturbances in both bone tissue metabolism and skeletal muscles quality and functions in patients with NAFLD. To date, the association between NAFLD and osteoporosis has been described in several studies, though it worth noting that most of them included postmenopausal women or elderly patients and originated from Asia. However, taking into account the health and economic burdens of NAFLD, and the increasing prevalence of obesity in children and adolescents worldwide, further investigation of the relationship between osteopenia, osteoporosis and sarcopenia in NAFLD, including in young and middle-aged patients, is of great importance. In addition, this will help to justify active screening and surveillance of osteopenia and osteoporosis in patients with NAFLD. In this review, we will discuss various pathophysiological mechanisms and possible biologically active molecules that may interplay between NAFLD and bone tissue metabolism.

1,25-Dihydroxycholecalciferol down-regulates 3-mercaptopyruvate sulfur transferase and caspase-3 in rat model of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the commonest cause of liver morbidity and mortality and has multiple unclear pathogenic mechanisms. Vitamin D deficiency was associated with increased incidence and severity of NAFLD. Increased hepatic expression of 3-mercaptopyruvate sulfur transferase (MPST) and dysregulated hepatocyte apoptosis were involved in NAFLD pathogenesis. We aimed to explore the protective effect of 1,25-Dihydroxycholecalciferol (1,25-(OH)₂ D3) against development of NAFLD and the possible underlying mechanisms, regarding hepatic MPST and caspase-3 expression. 60 male adult rats were divided into 4 and 12 week fed groups; each was subdivided into control, high-fat diet (HFD), and HFD + VD. Serum levels of lipid profile parameters, liver enzymes, insulin, glucose, C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), and hepatic levels of malondialdehyde (MDA), total antioxidant capacity (TAC), and reactive oxygen species (ROS) were measured. BMI and HOMA-IR were calculated, and liver tissues were processed for histopathological and immunohistochemical studies. The present study found that 1,25-(OH)₂ D3 significantly decreased BMI, HOMA-IR, serum levels of glucose, insulin, liver enzymes, lipid profile parameters, CRP, TNF-α, hepatic levels of MDA, ROS, hepatic expression of MPST, TNF-α, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and caspase-3; and significantly increased hepatic TAC in both HFD-fed groups. In conclusion: Administration of 1,25-(OH)₂ D3 with HFD abolished the NAFLD changes associated with HFD in 4-week group, and markedly attenuated the changes in 12-week group. The anti-apoptotic effect via decrement of caspase-3 and MPST expression are novel mechanisms suggested to be implicated in the protective effect of 1,25-(OH)₂ D3.

Linoleic acid-derived oxylipins and isoprostanes plasma levels are influenced by 1,25-Dihydroxyvitamin D levels in middle-aged sedentary adults: The FIT-AGEING study

INTRODUCTION

Vitamin D - concretely its active form 1,25-dihydroxyvitamin D (1,25(OH)₂D) - maintains several physiological processes. Oxylipins are oxidized lipids derived from ω-6 and ω-3 polyunsaturated fatty acids involved in inflammation. Little is known about the association of 1,25(OH)₂D with inflammatory parameters in middle-aged populations - who could be at risk of vitamin D deficiency -. The aim of this study was to investigate the relationship between 1,25(OH)₂D plasma levels with circulating white blood cells, platelets counts and oxylipins levels.

MATERIALS AND METHODS

A total of 74 (53 % women) middle-aged (40-65 years old) adults were recruited for this cross-sectional study. 1,25(OH)₂D plasma levels were measured using an immunochemiluminometric assay. White blood cells and platelets were analyzed by hemocytometry. ω-6 and ω-3 oxylipins plasma levels were measured using liquid chromatography - tandem mass spectrometry. Simple and multiple linear regression models, and Pearson correlation analyses, were performed to study the association of 1,25(OH)₂D levels with WBC and platelets counts, and oxylipins, respectively.

RESULTS

1,25(OH)₂D plasma levels were positively related with linoleic acid-derived oxylipins and isoprostanes plasma levels, whereas an inverse relationship with dihomo-γ-linolenic acid/linoleic acid and arachidonic acid/linoleic acid ratios was unveiled. No significant associations were observed for circulating ω-3 oxylipins, white blood cells levels or platelets count.

CONCLUSIONS

Linoleic acid-derived oxylipins and isoprostanes plasma levels may be influenced by 1,25(OH)₂D plasma levels. Further investigations are needed to elucidate the impact of other vitamin D forms upon circulating oxylipins levels.

Higher Serum 25-Hydroxyvitamin D Is Associated with Lower All-Cause and Cardiovascular Mortality among US Adults with Nonalcoholic Fatty Liver Disease

Aims: We aimed to assess the association between serum 25-hydroxyvitamin D (25(OH)D) levels with all-cause and cardiovascular mortality in patients with nonalcoholic fatty liver disease (NAFLD). Methods: We performed a retrospective cohort study based on the US National Health and Nutrition Examination Survey 2001–2016 on adults aged ≥20 years. NAFLD was determined as a US Fatty Liver Index score ≥ 30 in the absence of other liver conditions. Weighted Cox proportional hazards regression models were applied to explore the relationship between serum 25(OH)D levels and mortality. Results: 898 all-cause deaths and 305 cardiovascular deaths were recorded over a median follow-up of 8.7 years. Compared with those in the severe deficiency group (below 25.0 nmol/L), the fully adjusted HRs and 95% CIs of NAFLD patients with sufficient serum 25(OH)D concentrations (≥75.0 nmol/L) were 0.36 (0.22, 0.60) for all-cause mortality and 0.14 (0.07, 0.29) for cardiovascular mortality. Each one-unit increase in the natural log-transformed serum 25(OH)D concentration was related to a 41% lower risk for all-cause deaths (HR = 0.59, 95% CI: 0.46, 0.77) and a 65% lower risk for cardiovascular deaths (HR = 0.35, 95% CI: 0.22, 0.58). Conclusions: Among NAFLD patients, increased serum 25(OH)D levels were independently associated with reduced risk for all-cause and cardiovascular deaths.

The Role of Vitamin D and Vitamin D Binding Protein in Chronic Liver Diseases

Vitamin D (calciferol) is a fat-soluble vitamin that has a significant role in phospho-calcium metabolism, maintaining normal calcium levels and bone health development. The most important compounds of vitamin D are cholecalciferol (vitamin D3, or VD3) and ergocalciferol (vitamin D2, or VD2). Besides its major role in maintaining an adequate level of calcium and phosphate concentrations, vitamin D is involved in cell growth and differentiation and immune function. Recently, the association between vitamin D deficiency and the progression of fibrosis in chronic liver disease (CLD) was confirmed, given the hepatic activation process and high prevalence of vitamin D deficiency in these diseases. There are reports of vitamin D deficiency in CLD regardless of the etiology (chronic viral hepatitis, alcoholic cirrhosis, non-alcoholic fatty liver disease, primary biliary cirrhosis, or autoimmune hepatitis). Vitamin D binding protein (VDBP) is synthesized by the liver and has the role of binding and transporting vitamin D and its metabolites to the target organs. VDBP also plays an important role in inflammatory response secondary to tissue damage, being involved in the degradation of actin. As intense research during the last decades revealed the possible role of vitamin D in liver diseases, a deeper understanding of the vitamin D, vitamin D receptors (VDRs), and VDBP involvement in liver inflammation and fibrogenesis could represent the basis for the development of new strategies for diagnosis, prognosis, and treatment of liver diseases. This narrative review presents an overview of the evidence of the role of vitamin D and VDBP in CLD, both at the experimental and clinical levels.

Nonalcoholic steatohepatitis and mechanisms by which it is ameliorated by activation of the CNC-bZIP transcription factor Nrf2

Non-alcoholic steatohepatitis (NASH) represents a global health concern. It is characterised by fatty liver, hepatocyte cell death and inflammation, which are associated with lipotoxicity, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, iron overload and oxidative stress. NF-E2 p45-related factor 2 (Nrf2) is a transcription factor that combats oxidative stress. Remarkably, Nrf2 is downregulated during the development of NASH, which probably accelerates disease, whereas in pre-clinical studies the upregulation of Nrf2 inhibits NASH. We now review the scientific literature that proposes Nrf2 downregulation during NASH involves its increased ubiquitylation and proteasomal degradation, mediated by Kelch-like ECH-associated protein 1 (Keap1) and/or β-transducin repeat-containing protein (β-TrCP) and/or HMG-CoA reductase degradation protein 1 (Hrd1, also called synoviolin (SYVN1)). Additionally, downregulation of Nrf2-mediated transcription during NASH may involve diminished recruitment of coactivators by Nrf2, due to increased levels of activating transcription factor 3 (ATF3) and nuclear factor-kappaB (NF-κB) p65, or competition for promoter binding due to upregulation of BTB and CNC homology 1 (Bach1). Many processes that downregulate Nrf2 are triggered by transforming growth factor-beta (TGF-β), with oxidative stress amplifying its signalling. Oxidative stress may also increase suppression of Nrf2 by β-TrCP through facilitating formation of the DSGIS-containing phosphodegron in Nrf2 by glycogen synthase kinase-3. In animal models, knockout of Nrf2 increases susceptibility to NASH, while pharmacological activation of Nrf2 by inducing agents that target Keap1 inhibits development of NASH. These inducing agents probably counter Nrf2 downregulation affected by β-TrCP, Hrd1/SYVN1, ATF3, NF-κB p65 and Bach1, by suppressing oxidative stress. Activation of Nrf2 is also likely to inhibit NASH by ameliorating lipotoxicity, inflammation, ER stress and iron overload. Crucially, pharmacological activation of Nrf2 in mice in which NASH has already been established supresses liver steatosis and inflammation. There is therefore compelling evidence that pharmacological activation of Nrf2 provides a comprehensive multipronged strategy to treat NASH.

Vitamin D levels and oxidative stress markers in patients hospitalized with COVID-19

Background

COVID-19 is characterized by the presence of oxidative stress. Vitamin D status has been reviewed as one of the factors that may affect disease severity. The aim of this study was to assess the relationship between serum vitamin D levels, oxidative stress markers and disease severity in hospitalized COVID-19 patients.

Methods

Vitamin D levels were measured in 33 patients with COVID-19. The total antioxidant power and plasma peroxides were determined in serum.

Results

Severe COVID-19 patients have lower vitamin D levels (18.39 ± 2.29 ng/mL vs. 28.47 ± 3.05 ng/mL, p < .05) and higher oxidative stress compared to the moderate group. When divided according to serum vitamin D levels, significantly higher values of LDH (604.8 ± 76.98 IU/mL vs. 261.57 ± 47.33 IU/mL) and D-dimer (5978 ± 2028ng/mL vs. 977.7 ± 172 ng/mL) were obtained in the group with vitamin D below 30 ng/mL, followed with significantly higher levels of plasma peroxides (d-ROMs: 414.9 ± 15.82 U.Carr vs. 352.4 ± 18.77 U.Carr; p < .05) and oxidative stress index (OSI: 92.25 ± 6.60 vs. 51.89 ± 6.45; p < .001).

Conclusion

The presented data provide a justification to consider vitamin D as an important factor that could ameliorate disease severity through its anti-inflammatory and antioxidant effects.

The Role of Micronutrients in the Pathogenesis of Alcohol-Related Liver Disease

AIMS

Chronic alcohol consumption may result in liver injury and chronic liver disease, but other factors are likely to influence disease progression. Malnutrition, specifically micronutrient deficiency, is frequently associated with both alcohol use disorder and chronic liver disease. We hypothesize that micronutrient deficiencies may affect the progression of liver disease in this population.

METHODS

Systematic integrative review of the medical literature; electronic search of MEDLINE 1950-2021; studies investigating role of any micronutrient in the acceleration of alcohol-related liver injury in humans or animals. Studies which specifically related to alcoholic hepatitis were excluded. Outcomes were extracted and recorded in tabulated form and discussed narratively.

RESULTS

We identified 46 studies investigating the role of micronutrient deficiencies in the pathogenesis of alcohol-related liver disease. Specific micronutrients which were identified included folic acid or related B vitamins (n = 9 studies), Vitamin D (n = 9 studies), magnesium (n = 8 studies), zinc (n = 8 studies) and selenium (n = 12 including one systematic review). Observational evidence suggests a potential role of magnesium deficiency in accelerating alcohol-related liver injury with weak or negative evidence for other micronutrients.

CONCLUSIONS

Magnesium deficiency may increase the risk of alcohol-related liver injury and adverse liver outcomes. However, currently, there is insufficient evidence to support magnesium supplementation except for clinically relevant magnesium deficiency. Long-term prospective cohort studies assessing the impact of micronutrients on liver disease progression in patients with alcohol use disorder are lacking and may help determine whether there is a causal role for micronutrient deficiencies in alcohol-related liver injury.

Anthocyanins from the fruits of Lycium ruthenicum Murray improve high-fat diet-induced insulin resistance by ameliorating inflammation and oxidative stress in mice

A high-fat diet (HFD) promotes tissue inflammation, oxidative stress and insulin resistance (IR), thereby contributing to the development of obesity and diabetes. Anthocyanins from Lycium ruthenicum (AC) have demonstrated anti-obesity effects and modulated IR. To investigate the mechanism by which AC attenuates the adverse effects of consuming a HFD, C57BL/6J mice were fed a HFD supplemented with AC or a control diet without AC for 12 weeks. AC supplementation decreased the amount of weight gain, hepatic lipid, and sequentially improved dyslipidemia, inflammation, oxidative stress, and IR in HFD-fed mice. Molecular data revealed that AC inhibited hepatic inflammation by reducing TLR4/NF-κB/JNK in the liver tissues and ameliorated oxidative stress by activating the Nrf2/HO-1/NQO1 pathway. Thus, AC might activate IRS-1/AKT and prevent HFD-induced gluconeogenesis and IR by ameliorating inflammation and oxidative stress. Modulation of inflammation and oxidative stress with AC may represent a promising target for the treatment of IR and provide insight into the mechanism by which AC protects against obesity.

Role of Steroid Hormones in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and may progress to cirrhosis or even hepatocellular carcinoma. A number of steroid hormones are important regulators of lipid homeostasis through fine tuning the expression of genes related to lipid synthesis, export, and metabolism. Dysregulation of such pathways has been implicated in the pathogenesis of NAFLD. The aim of this review is to clarify the potential impact of steroid hormones on NAFLD. We also highlight potential interventions through modulating steroid hormone levels or the activities of their cognate receptors as therapeutic strategies for preventing NAFLD.

Oxidative Stress in Non-alcoholic Fatty Liver Disease. An Updated Mini Review

Non-alcoholic fatty liver disease (NAFLD) is a challenging disease caused by multiple factors, which may partly explain why it remains still orphan of an adequate therapeutic strategy. Herein we focus on the interplay between oxidative stress (OS) and the other causal pathogenetic factors. Different reactive oxygen species (ROS) generators contribute to NAFLD inflammatory and fibrotic progression, which is quite strictly linked to the lipotoxic liver injury from fatty acids and/or a wide variety of their biologically active metabolites in the context of either a two-hit or a (more recent) multiple parallel hits theory. An antioxidant defense system is usually able to protect hepatic cells from damaging effects caused by ROS, including those produced into the gastrointestinal tract, i.e., by-products generated by usual cellular metabolic processes, normal or dysbiotic microbiota, and/or diet through an enhanced gut–liver axis. Oxidative stress originating from the imbalance between ROS generation and antioxidant defenses is under the influence of individual genetic and epigenetic factors as well. Healthy diet and physical activity have been shown to be effective on NAFLD also with antioxidant mechanisms, but compliance to these lifestyles is very low. Among several considered antioxidants, vitamin E has been particularly studied; however, data are still contradictory. Some studies with natural polyphenols proposed for NAFLD prevention and treatment are encouraging. Probiotics, prebiotics, diet, or fecal microbiota transplantation represent new therapeutic approaches targeting the gut microbiota dysbiosis. In the near future, precision medicine taking into consideration genetic or environmental epigenetic risk factors will likely assist in further selecting the treatment that could work best for a specific patient.

The relationship between vitamin D deficiency and oxidative stress can be independent of age and gender

Abstract. The active vitamin D (1,25(OH)2D) acts through a nuclear receptor to perform several functions in cellular metabolism. 1,25(OH)2D participates directly in calcium homeostasis, regulates the immune system, nervous system, blood pressure, insulin secretion, among others. Vitamin D deficiency could also be associated with several diseases and increased cellular oxidative damage. The present study aimed to investigate whether lipid peroxidation and/or protein oxidation are affected by vitamin D deficiency and whether sunlight exposure/diet, gender, and age might influence this relationship. Vitamin D concentrations were obtained from the Heart Hospital database and a questionnaire was applied among the 212 participants. We used the inactive vitamin D (25(OH)2) in the analyses since 1,25(OH)2D has a short half-life and a low blood concentration. Lipid peroxidation and protein oxidation analyses were performed using spectrophotometry. Multivariate analyses suggested the participation of vitamin D deficiency (<30 ng/mL) and sunlight/diet in oxidative stress (p <0.05; R2 MDA: 0.562; R2 CG: 0.429). Multiple linear regression test show that the age and gender of patients are not interfering in the analyses (p>0.05). Therefore, we suggest that the relationship between vitamin D deficiency and oxidative stress can be independent of age and gender.

Vitamin D Level and Vitamin D Receptor Genetic Variation Were Involved in the Risk of Non-Alcoholic Fatty Liver Disease: A Case-Control Study

BACKGROUND

It has been demonstrated that vitamin D receptor (VDR), a key gene in the metabolism of vitamin D (VD), may affect the development of Non-alcoholic fatty liver disease (NAFLD) by regulating VD level and its biological effects.

OBJECTIVES

To investigate the effects of serum VD level, VDR variation, and a combination of VDR SNP and environmental behavior factor on the risk of NAFLD.

METHODS

A total of 3023 subjects from a community in Nanjing were enrolled, including 1120 NAFLD cases and 1903 controls. Serum 25(OH)D₃ levels were measured and eight single nucleotide polymorphisms (SNPs) in VDR gene were genotyped.

RESULTS

Logistic regression analyses indicated that VD sufficiency and VD insufficiency were significantly associated with a low risk of NAFLD (all P<0.05; all P_trend<0.05, in a locus-dosage manner). After adjusting for gender and age, VDR rs2228570-A and rs11168287-A alleles were all reduced the risk of NAFLD (all P_FDR=0.136, in dominant model; P_trend =0.039, combined effects in a locus-dosage manner). The protective effects of two favorable alleles were more evident among subjects ≤40 years, non-hypertension, non-hyperglycemia and non-low high density lipoprotein-cholesterol (all P<0.05). The area under the receiver operating curve of the combination of VDR SNP and exercise time for assessing NAFLD risk was slightly higher than that of only including exercise time or neither (all P<0.05).

CONCLUSION

High serum VD levels and VDR variants (rs2228570-A and rs11168287-A) might contribute to a low risk of NAFLD in Chinese Han population. The inclusion of VDR SNP and exercise time could improve the efficiency in assessment of NAFLD risk, which might provide a novel perspective for early screening and preventing NAFLD.

Vitamin D and Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD): An Update

Non-alcoholic fatty liver disease (NAFLD) is the first cause of chronic liver disease worldwide; it ranges from simple steatosis to steatohepatitis (NASH) and, potentially, cirrhosis and hepatocarcinoma. NAFLD is also an independent risk factor for type 2 diabetes, cardiovascular diseases, and mortality. As it is largely associated with insulin resistance and related disorders, NAFLD has been recently re-named as Metabolic dysfunction-Associated Fatty Liver Disease (MAFLD). At present, there are no approved pharmacological treatments for this condition. Vitamin D is a molecule with extensive anti-fibrotic, anti-inflammatory, and insulin-sensitizing properties, which have been proven also in hepatic cells and is involved in immune-metabolic pathways within the gut–adipose tissue–liver axis. Epidemiological data support a relationship hypovitaminosis D and the presence of NAFLD and steatohepatitis (NASH); however, results from vitamin D supplementation trials on liver outcomes are controversial. This narrative review provides an overview of the latest evidence on pathophysiological pathways connecting vitamin D to NAFLD, with emphasis on the effects of vitamin D treatment in MAFLD by a nonsystematic literature review of PubMed published clinical trials. This article conforms to the Scale for Assessment of Narrative Review Articles (SANRA) guidelines. Evidence so far available supports the hypothesis of potential benefits of vitamin D supplementation in selected populations of NAFLD patients, as those with shorter disease duration and mild to moderate liver damage.

Active vitamin D impedes the progression of non-alcoholic fatty liver disease by inhibiting cell senescence in a rat model

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) refers to an accumulation of excess fat in liver due to causes other than alcohol use. The relationship between vitamin D (VD) and NAFLD has been previously studied. Therefore, we aimed to explore the mechanism involved active VD regulating the progression of NAFLD by inhibiting cell senescence and to provide a potential approach for further nutritional treatment of NAFLD.

METHODS

Following the induction with high-fat diet and intraperitoneal injection of corn oil, the successfully established NAFLD rat models were treated with 1,25(OH)₂D₃ at 1μg/kg, 5μg/kg or 10μg/kg. Meanwhile, the levels of factors related to oxidative stress, cell senescence, the p53-p21 signaling pathway and inflammation in liver were determined. Then, cell senescence was also measured by using senescence-associated β-galactosidase (SAβ-gal) staining.

RESULTS

It was also found that active VD increased the concentration of VD in serum and VDR in liver of NAFLD rats, and alleviated hepatic fibrosis. Besides, treatment of 1,25(OH)₂D₃ at 1μg/kg, 5μg/kg or 10μg/kg reduced oxidative stress and inflammation, inhibited the p53-p21 signaling pathway and consequent cell senescence. Furthermore, treatment of 1,25(OH)₂D₃ at a dosage of 5μg/kg made the most impact on these factors.

CONCLUSION

Collectively, the evidences from this study demonstrated that active VD could alleviate the development of NAFLD through blocking the p53-p21 signaling pathway, which provided a novel nutritional therapeutic insight for NAFLD.

NRF-2 and nonalcoholic fatty liver disease

Currently, chronic liver diseases have conditioned morbidity and mortality, many of these with a metabolic, toxicologic, immunologic, viral, or other etiology. Thus, a transcription factor that has been of huge importance for biomedical research is NRF-2. The latter is considered a principal component of the antioxidant mechanism, and it has been acknowledged that it impairs the function of NRF-2 in many liver diseases and that it forms an essential part of the pathologic changes that occur in the liver to contain inflammation and damage. Within the investigations and experiments carried out, there are isolated drugs, many of them related to plants and natural extracts that possess antioxidant properties through the NRF-2 signaling pathway, or even involving the stimulation of the transcription target proteins of NRF-2. Notwithstanding all of these experimental findings, to date there is not sufficient clinical evidence to justify the use of NRF-2 in medical practice.

Low serum vitamin D is independently associated with unexplained elevated ALT only among non-obese men in the general population

INTRODUCTION AND OBJECTIVES

There are inconsistent findings on the association between human non-alcoholic fatty liver disease (NAFLD) and vitamin D, perhaps due to insufficient specificity for gender and obesity status. We aimed to assess whether serum levels of 25-hydroxyvitamin D are associated with unexplained elevated alanine aminotransferase (ALT) in general population across gender and body mass index (BMI) levels.

MATERIALS AND METHODS

A cross-sectional analysis of a population-based cohort with a nationwide-distribution using electronic medical database. The population consisted of individuals aged 20-60 years who underwent blood tests for ALT and vitamin D.

RESULTS

A total of 82,553 subjects were included (32.5% men, mean age 43.91±10.15 years). The prevalence of elevated ALT was higher among men and women with vitamin D insufficiency or deficiency, but in multivariate analysis, adjusting for: age, BMI, serum levels of glucose, total cholesterol, triglycerides, statin use and season, only the association among men remained significant for the vitamin D deficiency category (OR=1.16, 95%CI 1.04-1.29, P=0.010). Stratification by BMI revealed that only among normal weight and overweight men vitamin D deficiency was associated with elevated ALT (OR=1.27, 95%CI 1.01-1.59, P=0.041 and OR=1.27, 95%CI 1.08-1.50, P=0.003, respectively). No independent association was shown among women at all BMI categories.

CONCLUSIONS

In a "real-life" general population, the association between vitamin D deficiency and unexplained elevated ALT is specific for non-obese men. The clinical significance of vitamin D for human NAFLD should be further elucidated with attention for a modifying effect of gender and adiposity.

Lonicera caerulea L. Polyphenols Alleviate Oxidative Stress-Induced Intestinal Environment Imbalance and Lipopolysaccharide-Induced Liver Injury in HFD-Fed Rats by Regulating the Nrf2/HO-1/NQO1 and MAPK Pathways

SCOPE

This study investigates the modulatory effects of Lonicera caerulea L. polyphenols (LCPs) on the intestinal environment and lipopolysaccharide (LPS)-induced liver injury via the nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (HO-1)/NQO1 and mitogen-activated protein kinase (MAPK) pathways in a rat model of oxidative stress damage (OSD).

METHODS AND RESULTS

To examine the prebiotic properties of LCP, a model of high-fat-diet-induced OSD is established using Sprague Dawley rats. In the colon, treatment with LCP for 8 weeks ameliorates enhanced intestinal permeability (glucagon-like peptide-2 content and occludin protein increase, whereas claudin-2 protein decreases), intestinal inflammation (levels of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6, cyclooxygenase-2, and nuclear factor kappa-B p65 (NF-κB p65), decrease), and intestinal OSD (through regulation of the Nrf2/HO-1/NQO1 pathway). Moreover, LCP alleviates LPS-induced liver injury by suppressing the nuclear translocation of NF-κB p65 and activation of the MAPK signaling pathway. Additionally, Bacilli, Lactobacillales, Lactobacillaceae, Lactobacillus, Akkermansia, Actinobacteria, Proteobacteria, Rothia, and Blautia are found to be the key intestinal microbial taxa related to intestinal OSD and LPS-induced liver injury in rats.

CONCLUSION

LCP treatment potentially modulates the intestinal environment and alleviates liver injury by suppressing oxidative-stress-related pathways and altering the composition of the intestinal microbiota.

Vitamin D Deficiency Aggravates Hepatic Oxidative Stress and Inflammation during Chronic Alcohol-Induced Liver Injury in Mice

Vitamin D deficiency has been reported in alcoholics. This study is aimed at evaluating the effects of vitamin D deficiency on chronic alcohol-induced liver injury in mice. Mice were fed with modified Lieber-DeCarli liquid diets for 6 weeks to establish an animal model of chronic alcohol-induced liver injury. In the VDD+EtOH group, mice were fed with modified diets, in which vitamin D was depleted. Vitamin D deficiency aggravated alcohol-induced liver injury. Furthermore, vitamin D deficiency aggravated hepatocyte apoptosis during alcohol-induced liver injury. Although it has a little effect on hepatic TG content, vitamin D deficiency promoted alcohol-induced hepatic GSH depletion and lipid peroxidation. Further analysis showed that vitamin D deficiency further increased alcohol-induced upregulation of hepatic inducible nitric oxide synthase (inos), two NADPH oxidase subunits p47phox and gp91phox, and heme oxygenase- (HO-) 1. By contrast, vitamin D deficiency attenuated alcohol-induced upregulation of hepatic antioxidant enzyme genes, such as superoxide dismutase (sod) 1 and gshpx. In addition, vitamin D deficiency significantly elevated alcohol-induced upregulation of hepatic proinflammatory cytokines and chemokines. Taken together, these results suggest that vitamin D deficiency aggravates hepatic oxidative stress and inflammation during chronic alcohol-induced liver injury.

Association between calcitriol and paricalcitol with oxidative stress in patients with hemodialysis

Background: The pathophysiological basis of chronic kidney disease and its complications, including cardiovascular disease, are associated with chronic inflammation and oxidative stress. We investigated the effects of active vitamin D (calcitriol) and synthetic vitamin D analog (paricalcitol) on oxidative stress in hemodialysis patients. Methods: This cross-sectional study was composed of 83 patients with a minimum hemodialysis vintage of one year. Patients with a history of any infection, malignancy, and chronic inflammatory disease were excluded. Oxidative markers (total oxidant and antioxidant status) and inflammation markers (C-reactive protein and interleukin-6) were analyzed. Results: A total of 47% (39/83) patients were using active or analog vitamin D. Total antioxidant status was significantly higher in patients with using active or analog vitamin D than those who did not use (p = 0.006). Whereas, total oxidant status and oxidative stress index were significantly higher in patients with not using vitamin D when compared with the patients who were using vitamin D preparation (p = 0.005 and p = 0.004, respectively). On the other hand, total antioxidant status, total oxidant status, and oxidative stress index were similar between patients who used active vitamin D or vitamin D analog (p = 0.6; p = 0.4 and p = 0.7, respectively). Conclusion: The use of active or selective vitamin D analog in these patients decreases total oxidant status and increases total antioxidant status. Also, paricalcitol is as effective as calcitriol in decreasing total oxidant status and increasing total antioxidant status in patients with chronic kidney disease.

Bone mesenchymal stem cell-derived exosomal microRNA-29b-3p prevents hypoxic-ischemic injury in rat brain by activating the PTEN-mediated Akt signaling pathway

BACKGROUND

Mesenchymal stem cells (MSCs) are suspected to exert neuroprotective effects in brain injury, in part through the secretion of extracellular vesicles like exosomes containing bioactive compounds. We now investigate the mechanism by which bone marrow MSCs (BMSCs)-derived exosomes harboring the small non-coding RNA miR-29b-3p protect against hypoxic-ischemic brain injury in rats.

METHODS

We established a rat model of middle cerebral artery occlusion (MCAO) and primary cortical neuron or brain microvascular endothelial cell (BMEC) models of oxygen and glucose deprivation (OGD). Exosomes were isolated from the culture medium of BMSCs. We treated the MCAO rats with BMSC-derived exosomes in vivo, and likewise the OGD-treated neurons and BMECs in vitro. We then measured apoptosis- and angiogenesis-related features using TUNEL and CD31 immunohistochemical staining and in vitro Matrigel angiogenesis assays.

RESULTS

The dual luciferase reporter gene assay showed that miR-29b-3p targeted the protein phosphatase and tensin homolog (PTEN). miR-29b-3p was downregulated and PTEN was upregulated in the brain of MCAO rats and in OGD-treated cultured neurons. MCAO rats and OGD-treated neurons showed promoted apoptosis and decreased angiogenesis, but overexpression of miR-29b-3p or silencing of PTEN could reverse these alterations. Furthermore, miR-29b-3p could negatively regulate PTEN and activate the Akt signaling pathway. BMSCs-derived exosomes also exerted protective effects against apoptosis of OGD neurons and cell apoptosis in the brain samples from MCAO rats, where we also observed promotion of angiogenesis.

CONCLUSION

BMSC-derived exosomal miR-29b-3p ameliorates ischemic brain injury by promoting angiogenesis and suppressing neuronal apoptosis, a finding which may be of great significance in the treatment of hypoxic-ischemic brain injury.

Preparation and Evaluation of Functional Foods for Prevention of Non-alcoholic Fatty Liver Disease

BACKGROUND AND OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is a public health problem presenting one of the most important common forms of liver diseases worldwide. This study was carried out to investigate the protective effect of two functional foods in form of bread containing purslane seeds meal and garden cress seeds against NAFLD.

MATERIALS AND METHODS

High fat and high cholesterol diet were used for induction of NAFLD in rats for 6 weeks. Plasma lipid profile (total cholesterol, triglycerides, high density lipoprotein-cholesterol and low-density lipoprotein-cholesterol, hepatic lipid profile (total fat, cholesterol, triglycerides), malondialdehyde (MDA), as well as liver (AST, ALT, total and direct bilirubin) and kidney (creatinine and urea) functions were assessed. Histological examination of liver tissue was carried out.

RESULTS

Results revealed that significant elevation in plasma and liver lipid profiles, MDA, liver enzymes (AST and ALT), bilirubin (total and direct) and kidney function (creatinine and urea) were observed in NAFLD control compared to normal control. Feeding rats on diet containing functional food I and II (purslane and garden cress bread, respectively) showed significant improvement in all the studied parameters with remarkable effect regards to functional food I (purslane bread).

CONCLUSION

Purslane bread and garden cress bread as functional foods prepared in the present study prevent weight gain, improve plasma lipid profile and prevent hepatic lipid accumulation effectively in NAFLD model in rats. Also decreased lipid peroxidation, improve liver and kidney functions and possess hypoglycemic effect. Purslane bread was superior in the prevention of hepatic lipid accumulation.

Dihydroartemisinin attenuates alcoholic fatty liver through regulation of lipin-1 signaling

Alcoholic liver disease (ALD) is generated from excessive alcohol consumption, characterized by hepatic steatosis. Mechanistically, excessive hepatic lipid accumulation was attributed to the aberrant lipin-1 signaling during the development of alcoholic steatosis in rodent species and human. Dihydroartemisinin (DHA) has been recently identified to relieve hepatocytes necrosis and prevent from hepatic steatosis in alcohol-induced liver diseases; however, the role of DHA in ALD has not been elucidated completely. Therefore, this study was aimed to further identify the potential mechanisms of pharmacological effects of DHA on ALD. Results demonstrated that DHA regulated the expression and nucleocytoplasmic shuttling of lipin-1 in mice with chronic ethanol exposure. Results confirmed that the disruption of lipin-1 signaling abolished the suppression of DHA on alcohol-induced hepatic steatosis. Interestingly, DHA also significantly improved liver injury, and inflammation mediated by lipin-1 signaling in chronic alcohol-fed mice. in vivo experiments further consolidated the concept that DHA protected against hepatocyte lipoapoptosis dependent on the regulation of nucleocytoplasmic shuttling of lipin-1 signaling, resulting in attenuated ratio of Lpin1 β/α. Obvious increases in cell apoptosis were observed in alcohol-treated lipin1β-overexpressed mice. Although DHA attenuated cell apoptosis, overexpression of lipin-1β neutralized DHA action. DHA ameliorated activation of endoplasmic reticulum stress through inhibiting activation of JNK and CHOP, which was abrogated by overexpression of lipin-1β. In summary, DHA significantly improved liver injury, steatosis and hepatocyte lipoapoptosis in chronic alcohol-fed mice via regulation of lipin-1 signaling.

Redox Regulation of Metabolic Syndrome: Recent Developments in Skeletal Muscle Insulin Resistance and Non-alcoholic Fatty Liver Disease (NAFLD)

Several new discoveries over the past decade have shown that metabolic syndrome, a cluster of metabolic disorders, including increased visceral obesity, hyperglycemia, hypertension, dyslipidemia and low HDL-cholesterol, is commonly associated with skeletal muscle insulin resistance. More recently, non-alcoholic fatty liver disease (NAFLD) was recognized as an additional condition that is strongly associated with features of metabolic syndrome. While the pathogenesis of skeletal muscle insulin resistance and fatty liver is multifactorial, the role of dysregulated redox signaling has been clearly demonstrated in the regulation of skeletal muscle insulin resistance and NAFLD. In this review, we aim to provide recent updates on redox regulation with respect to (a) pro-oxidant enzymes (e.g. NAPDH oxidase and xanthine oxidase); (b) mitochondrial dysfunction; (c) endoplasmic reticulum (ER) stress; (d) iron metabolism derangements; and (e) gut-skeletal muscle or gut-liver connection in the development of skeletal muscle insulin resistance and NAFLD. Furthermore, we discuss promising new therapeutic strategies targeting redox regulation currently under investigation for the treatment of skeletal muscle insulin resistance and NAFLD.

The Role of Vitamin D and Oxidative Stress in Chronic Kidney Disease

Chronic kidney disease (CKD) is a major non-communicable disease associated with high rates of premature morbidity and mortality. The prevalence of hypovitaminosis D (deficiency of 25(OH)D or 25D) is greater in racial/ethnic minorities and in patients with CKD than the general population. Low 25D is associated with bone and mineral disorders as well as immune, cardiometabolic and cardiovascular (CV) diseases. Thus, it has been suggested that low 25D contributes to the poor outcomes in patients with CKD. The prevalence of hypovitaminosis D rises progressively with advancing severity of kidney disease with over 30% of patients with CKD stage 3 and 70% patients with CKD stage 5 estimated to have low levels of 25D. This report describes several of the abnormal physiologic and counter-regulatory actions related to low 25D in CKD such as those in oxidative stress and inflammatory systems, and some of the preclinical and clinical evidence, or lack thereof, of normalizing serum 25D levels to improve outcomes in patients with CKD, and especially for the high risk subset of racial/ethnic minorities who suffer from higher rates of advanced CKD and hypovitaminosis D.

Cigarette Smoke During Breastfeeding in Rats Changes Glucocorticoid and Vitamin D Status in Obese Adult Offspring

Maternal smoking increases obesogenesis in the progeny. Obesity is associated with several hormonal dysfunctions. In a rat model of postnatal tobacco smoke exposure, we previously reported increased central fat depot and disruption of some hormonal systems in the adult offspring. As both glucocorticoids and vitamin D alter lipogenesis and adipogenesis, here we evaluated the metabolism of these two hormones in visceral adipose tissue (VAT) and liver by Western blotting, and possible associations with lipogenesis biomarkers in adult rats that were exposed to tobacco smoke during their suckling period. At postnatal day (PN) 3, dams and offspring of both sexes were exposed (S group) or not (C group) to tobacco smoke, 4 × 1 h/day. At PN180, corticosteronemia was lower in S male and higher in S female offspring, without alterations in peripheral glucocorticoid metabolism and receptor. Adrenal ACTH receptor (MC2R) was higher in both sexes of S group. Despite unchanged serum vitamin D, liver 25-hydroxylase was higher in both sexes of S group. Male S offspring had higher 1α-hydroxylase, acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS) in VAT. Both sexes showed increased ACC protein content and reduced sirtuin mRNA in liver. Male S offspring had lower liver peroxisome proliferator-activated receptor-α. Tobacco exposure during lactation induced abdominal obesity in both sexes via distinct mechanisms. Males and females seem to develop HPA-axis dysfunction instead of changes in glucocorticoid metabolism and action. Lipogenesis in VAT and liver, as well as vitamin D status, are more influenced by postnatal smoke exposure in male than in female adult rat offspring.

Self-assembly and directed assembly of lipid nanocarriers for prevention of liver fibrosis in obese rats: a comparison with the therapy of bariatric surgery

Aim: Whether the obesity prevention by chemicals or surgeries in already obese patients is the better choice remains controversial. We aimed to compare the effect of orally silibinin-loaded nanocarriers and Roux-en-Y gastric bypass surgery on hepatic fibrosis in high-fat feeding-induced obese rats. Methodology: The developed nanocarriers included self-emulsifying drug delivery system (SNEDDS) and nanostructured lipid carriers (NLC). Results: A significant decrease in collagen production and lipid droplet formation was observed upon nanosystem and bariatric surgery than the rats treated with silibinin control suspension. Stage 3 fibrosis was present in 33% of the obese rats. This percentage could be minimized to 0% by SNEDDS and NLC. Following oral administration, SNEDDS and NLC resulted in 3.5- and 2.9-fold increase, respectively, in bioavailability compared with the reference suspension. Conclusion: Nanomedicine prevention provided a comparable efficiency to ameliorate liver steatosis as Roux-en-Y gastric bypass due to the improvement of silibinin dissolution and gastrointestinal permeation.

Mitochondria and Reactive Oxygen Species in Aging and Age-Related Diseases

Aging has been linked to several degenerative processes that, through the accumulation of molecular and cellular damage, can progressively lead to cell dysfunction and organ failure. Human aging is linked with a higher risk for individuals to develop cancer, neurodegenerative, cardiovascular, and metabolic disorders. The understanding of the molecular basis of aging and associated diseases has been one major challenge of scientific research over the last decades. Mitochondria, the center of oxidative metabolism and principal site of reactive oxygen species (ROS) production, are crucial both in health and in pathogenesis of many diseases. Redox signaling is important for the modulation of cell functions and several studies indicate a dual role for ROS in cell physiology. In fact, high concentrations of ROS are pathogenic and can cause severe damage to cell and organelle membranes, DNA, and proteins. On the other hand, moderate amounts of ROS are essential for the maintenance of several biological processes, including gene expression. In this review, we provide an update regarding the key roles of ROS-mitochondria cross talk in different fundamental physiological or pathological situations accompanying aging and highlighting that mitochondrial ROS may be a decisive target in clinical practice.

Effects of Vitamin D3 on the NADPH Oxidase and Matrix Metalloproteinase 9 in an Animal Model of Global Cerebral Ischemia

Decreased blood flow in the brain leads to a rapid increase in reactive oxygen species (ROS). NADPH oxidase (NOX) is an enzyme family that has the physiological function to produce ROS. NOX2 and NOX4 overexpression is associated with aggravated ischemic injury, while NOX2/4-deficient mice had reduced stroke size. Dysregulation of matrix metalloproteinases (MMPs) contributes to tissue damage. The active form of vitamin D3 expresses neuroprotective, immunomodulatory, and anti-inflammatory effects in the CNS. The present study examines the effects of the vitamin D3 pretreatment on the oxidative stress parameters and the expression of NOX subunits, MMP9, microglial marker Iba1, and vitamin D receptor (VDR), in the cortex and hippocampus of Mongolian gerbils subjected to ten minutes of global cerebral ischemia, followed by 24 hours of reperfusion. The ischemia/reperfusion procedure has induced oxidative stress, changes in the expression of NOX2 subunits and MMP9 in the brain, and increased MMP9 activity in the serum of experimental animals. Pretreatment with vitamin D3 was especially effective on NOX2 subunits, MMP9, and the level of malondialdehyde and superoxide anion. These results outline the significance of the NOX and MMP9 investigation in brain ischemia and the importance of adequate vitamin D supplementation in ameliorating the injury caused by I/R.

Vitamin D nanoemulsion enhances hepatoprotective effect of conventional vitamin D in rats fed with a high-fat diet

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is associated with hyperlipidemia, obesity and type II diabetes. Due to increasing prevalence of these diseases globally, NAFLD is considered as a common form of chronic liver diseases. Vitamin D is a fat soluble vitamin with reported anti-inflammatory, anti-oxidant and immune modulating activity. Hypovitaminosis D often coexists with NAFLD and various studies reported beneficial role of vitamin D in modulating NAFLD. However, variable oral bioavailability, poor water solubility, and chemical degradation hinder the clinical application of vitamin D.

PURPOSE

We evaluated the potential protective effect of Vitamin D nanoemulsion (developed by sonication and pH-Shifting of pea protein isolate and canola oil) compared to conventional vitamin D against liver injury in rats fed with high fat diet (HFD).

METHODS

We analyzed liver function enzymes, lipid profile, lipid metabolism, levels and histopathology of inflammation and fibrosis in rat liver tissues.

RESULTS

HFD fed rats exhibited deterioration of liver function, poor lipid profile, decreased fatty acid oxidation and up-regulation of inflammatory cytokines and extracellular matrix deposition. Vitamin D administration reduced elevated liver enzymes, improved lipid profile, enhanced fatty acid oxidation and attenuated liver inflammation and fibrosis. Interestingly, vitamin D nanoemulsion was superior to conventional vitamin D with remarkable hepatoprotective effect against HFD-induced liver injury.

CONCLUSION

This study demonstrated vitamin D nanoemulsion as a more efficient formulation with more prominent hepatoprotective effect against HFD-induced liver injury compared to conventional oral vitamin D.

Vitamin D and Nonalcoholic Fatty Liver Disease: Bi-directional Mendelian Randomization Analysis

Background

Vitamin D deficiency is associated with nonalcoholic fatty liver disease (NAFLD) in many cross-sectional studies. However, the causality between them has not been established. We used bi-directional mendelian randomization (MR) analysis to explore the causal relationship between 25-hydroxyvitamin D [25(OH)D] and NAFLD.

Methods

9182 participants were included from a survey in East China from 2014 to 2016. We calculated weighted genetic risk scores (GRS) for 25(OH)D concentration and NAFLD based on 25(OH)D-related and NAFLD-related single nucleotide polymorphisms. Presence of liver steatosis was assessed using ultrasound. Instrumental variable was used to measure the causal relationship between them.

Results

An SD increase in the 25(OH)D GRS was significantly associated with 25(OH)D (β 1.29, 95%CI − 1.54, − 1.04, P < 0.05) but not with NAFLD (OR 0.97, 95%CI 0.92, 1.01). An SD increase in NAFLD GRS was also strongly associated with NAFLD (OR 1.09, 95%CI 1.04, 1.15, P < 0.05) but not with 25(OH)D (β − 0.15, 95%CI − 0.41, 0.10). Using an instrumental variable estimator, no associations were found for genetically instrumented 25(OH)D with NAFLD and for genetically instrumented NAFLD with 25(OH)D.

Conclusion

Our results support the conclusion that there is no causal association between vitamin D and NAFLD using a bi-directional MR approach in a Chinese population.

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The causality between vitamin D and NAFLD was controversial in human beings.

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Using mendelian randomization analysis, 25(OH)D and NAFLD are not causally associated.

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Long-term vitamin D deficiency may not affect the development of NAFLD.

Vitamin D supplementation and non-alcoholic fatty liver disease: A critical and systematic review of clinical trials

Previous observational studies have found a relationship between vitamin D deficiency and non-alcoholic fatty liver disease (NAFLD). However, this type of study could not show the causal relationship between these two conditions. Therefore, we systematically and critically reviewed the available clinical trials to elucidate such relationship. We searched databases such as Medline, Scopus and Cochrane to identify the clinical trials that assessed the effects of vitamin D supplementation in adults with NAFLD. The outcome variables of interest were indicators of hepatic steatosis, liver enzymes, insulin resistance, inflammation and oxidative stress. A total of 6 studies were included in the qualitative analysis. Only in two studies the grade of hepatic steatosis decreased significantly after vitamin D supplementation. The changes in insulin resistance parameters were reported significant only in one. Of the 3 included studies that measured biomarkers of inflammation and oxidative stress, one revealed a significant decrease in these biomarkers after vitamin D supplementation. Findings from current review study provided new insight into the factors that could affect the therapeutic role of vitamin D in NAFLD. Factors such as gender differences, baseline serum status of vitamin D, co-supplementation with calcium and gene polymorphism should be considered when designing future clinical trials.