Niacin ameliorates oxidative stress, inflammation, proteinuria, and hypertension in rats with chronic renal failure

L-shaped association between dietary niacin intake and chronic kidney disease among adults in the USA: a cross-sectional study

BACKGROUND

Chronic kidney disease (CKD), which has become a global public health issue, is associated with mitochondrial dysfunction. Niacin is a necessary coenzyme for mitochondrial energy metabolism. However, the association between dietary niacin intake and CKD remains uncertain. This study aimed to investigate the association between dietary niacin intake and CKD in American adults.

METHODS

This is a cross-sectional study. 25,608 individuals aged ≥20 years from the National Health and Nutrition Examination Survey from 2007 to 2018 were involved.Dietary niacin intake was estimated based on 24-hour dietary recalls conducted by trained personnel. CKD was determined by an estimated glomerular filtration rate (eGFR) (<60 ml/min/1.73 m2) or a urinary albumin-to-creatinine ratio (ACR) (≥30mg/g). The association between dietary niacin intake and CKD was investigated using multivariable logistic regression analysis.

RESULTS

Of 25,608 participants, 17.14% (4388/25,608) had CKD. Compared to individuals with lower niacin intake (quartile [Q]1, ≤15.30 mg/day), those with higher niacin intake in Q2 (15.31-22.07 mg/day), Q3 (22.08-31.09 mg/day), and Q4 (≥31.10 mg/day) exhibited adjusted odds ratios for CKD of 0.89 (95% confidence interval [CI]:0.81-0.99, p = 0.024), 0.83 (95% CI:0.75-0 .92, p < 0 .001), and 0.83 (95% CI:0.75-0.93, p = 0.001) respectively. The relationship between dietary niacin intake and CKD among U.S. adults follows an L-shaped pattern, with an inflection point at approximately 28.04 mg/day.

CONCLUSIONS

These results suggest an L-shaped association between dietary niacin intake and CKD. Individuals with low dietary niacin intake levels should be alert to the risk of CKD.

A disturbed metabolite-GPCR axis is associated with microbial dysbiosis in IBD patients: Potential role of GPR109A in macrophages

Inflammatory Bowel Disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract characterized by disrupted immune function. Indeed, gut microbiota dysbiosis and metabolomic profile alterations, are hallmarks of IBD. In this scenario, metabolite-sensing G-protein coupled receptors (GPCRs), involved in several biological processes, have emerged as pivotal players in the pathophysiology of IBD. The aim of this study was to characterize the axis microbiota-metabolite-GPCR in intestinal surgical resections from IBD patients. Results showed that UC patients had a lower microbiota richness and bacterial load, with a higher proportion of the genus Cellulosimicrobium and a reduced proportion of Escherichia, whereas CD patients showed a decreased abundance of Enterococcus. Furthermore, metabolomic analysis revealed alterations in carboxylic acids, fatty acids, and amino acids in UC and CD samples. These patients also exhibited upregulated expression of most metabolite-sensing GPCRs analysed, which positively correlated with pro-inflammatory and pro-fibrotic markers. The role of GPR109A was studied in depth and increased expression of this receptor was detected in epithelial cells and cells from lamina propria, including CD68+ macrophages, in IBD patients. The treatment with β-hydroxybutyrate increased gene expression of GPR109A, CD86, IL1B and NOS2 in U937-derived macrophages. Besides, when GPR109A was transiently silenced, the mRNA expression and secretion of IL-1β, IL-6 and TNF-α were impaired in M1 macrophages. Finally, the secretome from siGPR109A M1 macrophages reduced the gene and protein expression of COL1A1 and COL3A1 in intestinal fibroblasts. A better understanding of metabolite-sensing GPCRs, such as GPR109A, could establish their potential as therapeutic targets for managing IBD.

Hepatoprotective Effect of Nicotinamide Versus Lead-Motivated Hepatotoxicity in Rats via Correcting Effect on Nuclear Factor-kβ Pathway and Glutathione Metabolism

Lead (Pb) poisoning is one of the pivotal environmental issues and prompts liver dysfunction by elevating oxidative stress and inflammation. Nicotinamide (NA) deficiency enhances sensitivity to Pb toxicity. So, we investigated the effect of nicotinamide (NA) on the rat's liver histopathological and biochemical profiles in a rat model of Pb toxicity. Thirty-six rats were divided into four groups (nine rats at each): normal (N), lead toxicity (Pbt), and NA-treated N and Pbt groups. Treated groups took NA (180 mg/L in drinking water for one month). Pb intoxication was motivated in rats by acquiring 50 mg/L lead acetate in drinking water. Oxidative stress markers (advanced oxidation protein products and malondialdehyde), antioxidant markers (total glutathione, reduced glutathione to oxidized glutathione ratio, ferric ion reducing power, catalase, and paraoxonase-1), and inflammatory markers (hepatic nuclear factor-kβ expression, interleukin 1β level, and myeloperoxidase activity) in sera and liver homogenates were determined. In addition, the biochemical parameters of the liver function were measured. Finally, the liver of rats was evaluated by histopathological observation. NA corrected lead-persuaded biochemical and histopathological changes in the rat's liver. In addition, treatment decreased Pb, oxidative stress, and inflammatory markers in the sera and liver homogenates of N and Pbt groups. In addition, it elevated antioxidant markers (p < 0.001). NA prevented Pb-induced liver histopathological alternations and reduced liver dysfunction by reducing Pb, oxidative stress, and inflammation. Moreover, raising GSH/GSSG and diminishing the hepatic NF-kβ pathway are cardinal mechanisms of the treatment against Pb-motivated hepatotoxicity in rats.

Research progress on the role and inhibitors of Keap1 signaling pathway in inflammation

Inflammation is a protective mechanism against endogenous and exogenous pathogens. It is a typical feature of numerous chronic diseases and their complications. Keap1 is an essential target in oxidative stress and inflammatory diseases. Among them, the Keap1-Nrf2-ARE pathway (including Keap1-Nrf2-HO-1) is the most significant pathway of Keap1 targets, which participates in the control of inflammation in multiple organs (including renal inflammation, lung inflammation, liver inflammation, neuroinflammation, etc.). Identifying new Keap1 inhibitors is crucial for new drug discovery. However, most drugs have specificity issues as they covalently bind to cysteine residues of Keap1, causing off-target effects. Therefore, direct inhibition of Keap1-Nrf2 PPIs is a new research idea. Through non-electrophilic and non-covalent binding, its inhibitors have better specificity and ability to activate Nrf2, and targeting therapy against Keap1-Nrf2 PPIs has become a new method for drug development in chronic diseases. This review summarizes the members and downstream genes of the Keap1-related pathway and their roles in inflammatory disease models. In addition, we summarize all the research progress of anti-inflammatory drugs targeting Keap1 from 2010 to 2024, mainly describing their biological functions, molecular mechanisms of action, and therapeutic roles in inflammatory diseases.

The Antioxidant Potential of Vitamins and Their Implication in Metabolic Abnormalities

Vitamins are micronutrients necessary for the normal function of the body. Although each vitamin has different physicochemical properties and a specific role in maintaining life, they may also possess a common characteristic, i.e., antioxidant activity. Oxidative stress can harm all the main biological structures leading to protein, DNA and lipid oxidation, with concomitant impairment of the cell. It has been established that oxidative stress is implicated in several pathological conditions such as atherosclerosis, diabetes, obesity, inflammation and metabolic syndrome. In this review we investigate the influence of oxidative stress on the above conditions, examine the interrelation between oxidative stress and inflammation and point out the importance of vitamins in these processes, especially in oxidative load manipulation and metabolic abnormalities.

The Pleiotropic Effects of Lipid-Modifying Interventions: Exploring Traditional and Emerging Hypolipidemic Therapies

Atherosclerotic cardiovascular disease poses a significant global health issue, with dyslipidemia standing out as a major risk factor. In recent decades, lipid-lowering therapies have evolved significantly, with statins emerging as the cornerstone treatment. These interventions play a crucial role in both primary and secondary prevention by effectively reducing cardiovascular risk through lipid profile enhancements. Beyond their primary lipid-lowering effects, extensive research indicates that these therapies exhibit pleiotropic actions, offering additional health benefits. These include anti-inflammatory properties, improvements in vascular health and glucose metabolism, and potential implications in cancer management. While statins and ezetimibe have been extensively studied, newer lipid-lowering agents also demonstrate similar pleiotropic effects, even in the absence of direct cardiovascular benefits. This narrative review explores the diverse pleiotropic properties of lipid-modifying therapies, emphasizing their non-lipid effects that contribute to reducing cardiovascular burden and exploring emerging benefits for non-cardiovascular conditions. Mechanistic insights into these actions are discussed alongside their potential therapeutic implications.

The potential prophylactic and therapeutic impacts of niacin on ischemia/reperfusion injury of testis

INTRODUCTION

The testicular ischemia-reperfusion (I/R) injury is characterized by the excessive aggregation of un-scavenged reactive oxygen species, leading to the heightened levels of oxidative stress. This phenomenon plays a pivotal role in the pathophysiology of testicular torsion damage.

OBJECTIVE

The current study aimed to detect the prophylactic and therapeutic effects of niacin on testicular I/R injury.

STUDY DESIGN

Twenty-four healthy adult male Sprague Dawley rats were randomly allocated into three groups as follows: (1) sham group, (2) torsion/detorsion (T/D) group, and (3) treatment group which received 200 mg/kg niacin along with testicular T/D. Torsion/detorsion was induced by 2 h of torsion followed by 10 days of reperfusion period. In the treatment group, niacin was injected 30 min before the reperfusion period intraperitoneally and continued for 10 days by oral gavage.

RESULTS

T/D was associated with marked decreases in terms of sperm count, viability, and kinematic parameters versus the sham group (P < 0.05), which niacin significantly reverted the kinematic parameters (P < 0.05). I/R injury caused a significant increase in the number of abnormal epididymal sperms compared to the sham group (P < 0.05). Niacin decreased the epididymal sperm abnormality significantly compared to the T/D group (P < 0.05). Tissue abnormalities in T/D group, such as edema, hyperemia, inflammation, and necrosis were completely visible histopathologically, while the histological changes in the niacin-treated group were better than those in the T/D group. Regarding the pathological parametric evaluations, I/R injury significantly reduced the mean testicular biopsy score (MTBS), germinal epithelial cell thickness (GECT), and mean seminiferous tubular diameter (MSTD), and increased the tubular hypoplasia/atrophy (THA) compared to the sham group (P < 0.05), which niacin treatment significantly improved the MTBS and GECT compared to the T/D group (P < 0.05). T/D significantly increased the oxidative stress index (OSI) and lipid peroxidation (MDA) (P < 0.05). Niacin significantly reduced the OSI and MDA levels compared to the T/D group (P < 0.05).

DISCUSSION

The current study found that niacin has preventive/therapeutic effects against the elevation of oxidative stress markers and depletion of antioxidants during I/R injury. Following administration of niacin, a reduction in histologic injury was observed in rats. In our study, we showed the antioxidant properties of niacin and its capacity to protect against I/R damage.

CONCLUSION

The findings of the present investigation revealed that niacin, as an antioxidant agent, can suppress the oxidative stress induced by testicular I/R injury, and can be used as a supplementary agent in the treatment of those undergoing testicular torsion surgery.

Assessing the effects of tempol on renal fibrosis, inflammation, and oxidative stress in a high-salt diet combined with 5/6 nephrectomy rat model: utilizing oxidized albumin as a biomarker

BACKGROUND

Oxidative stress has been implicated in the pathogenesis of chronic kidney disease (CKD), prompting the exploration of antioxidants as a potential therapeutic avenue for mitigating disease progression. This study aims to investigate the beneficial impact of Tempol on the progression of CKD in a rat model utilizing oxidized albumin as a biomarker.

METHODS

After four weeks of treatment, metabolic parameters, including body weight, left ventricle residual weight, kidney weight, urine volume, and water and food intake, were measured. Systolic blood pressure, urinary protein, oxidized albumin level, serum creatinine (Scr), blood urea nitrogen (BUN), 8-OHdG, TGF-β1, and micro-albumin were also assessed. Renal fibrosis was evaluated through histological and biochemical assays. P65-NF-κB was quantified using an immunofluorescence test, while Smad3, P65-NF-κB, and Collagen I were measured using western blot. TNF-α, IL-6, MCP-1, TGF-β1, Smad3, and P65-NF-κB were analyzed by RT-qPCR.

RESULTS

Rats in the high-salt diet group exhibited impaired renal function, characterized by elevated levels of blood urea nitrogen, serum creatinine, 8-OHdG, urine albumin, and tubulointerstitial damage, along with reduced body weight. However, these effects were significantly ameliorated by Tempol administration. In the high-salt diet group, blood pressure, urinary protein, and oxidized albumin levels were notably higher compared to the normal diet group, but Tempol administration in the treatment group reversed these effects. Rats in the high-salt diet group also displayed increased levels of proinflammatory factors (TNF-α, IL-6, MCP1) and profibrotic factors (NF-κB activation, Collagen I), elevated expression of NADPH oxidation-related subunits (P65), and activation of the TGF-β1/Smad3 signaling pathway. Tempol treatment inhibited NF-κB-mediated inflammation and TGF-β1/Smad3-induced renal fibrosis signaling pathway activation.

CONCLUSION

These findings suggest that Tempol may hold therapeutic potential for preventing and treating rats undergoing 5/6 nephrectomy. Further research is warranted to elucidate the mechanisms underlying Tempol's protective effects and its potential clinical applications. Besides, there is a discernible positive relationship between oxidized albumin and other biomarkers, such as 8-OHG, urinary protein levels, mALB, Scr, BUN, and TGF-β1 in a High-salt diet combined with 5/6 nephrectomy rat model. These findings suggest the potential utility of oxidized albumin as a sensitive indicator for oxidative stress assessment.

Jian-Pi-Yi-Shen formula alleviates renal fibrosis by restoring NAD+ biosynthesis in vivo and in vitro

BACKGROUND

Patients with chronic kidney disease (CKD) lack efficacious treatment. Jian-Pi-Yi-Shen formula (JPYSF) has demonstrated significant clinical efficacy in treating CKD for decades. However, its renoprotective mechanism has not been fully elucidated. This study aimed to determine whether JPYSF could delay renal fibrosis progression in CKD by restoring nicotinamide adenine dinucleotide (NAD+) biosynthesis.

METHODS

Adenine-diet feeding was used to model CKD in C57BL/6 mice. JPYSF was orally administered for 4 weeks. Human proximal tubular epithelial cells (HK-2) cells were stimulated with transforming growth factor-β1 (TGF-β1) with or without JPYSF treatment. Renal function of mice was assessed by serum creatinine and blood urea nitrogen levels. Renal histopathological changes were assessed using Periodic acid-Schiff and Masson's trichrome staining. Cell viability was assessed using a cell counting kit-8 assay. NAD+ concentrations were detected by a NAD+/NADH assay kit. Western blotting, immunohistochemistry, and immunofluorescence were employed to examine fibrosis-related proteins and key NAD+ biosynthesis enzymes expression in the CKD kidney and TGF-β1-induced HK-2 cells.

RESULTS

JPYSF treatment could not only improve renal function and pathological injury but also inhibit renal fibrosis in CKD mice. Additionally, JPYSF reversed fibrotic response in TGF-β1-induced HK-2 cells. Moreover, JPYSF rescued the decreased NAD+ content in CKD mice and TGF-β1-induced HK-2 cells through restoring expression of key enzymes in NAD+ biosynthesis, including quinolinate phosphoribosyltransferase, nicotinamide mononucleotide adenylyltransferase 1, and nicotinamide riboside kinase 1.

CONCLUSIONS

JPYSF alleviated renal fibrosis in CKD mice and reversed fibrotic response in TGF-β1-induced HK-2 cells, which may be related to the restoration of NAD+ biosynthesis.

Protective effects of niacin following high fat rich diet: an in-vivo and in-silico study

Niacin had long been understood as an antioxidant. There were reports that high fat diet (HFD) may cause psychological and physical impairments. The present study was aimed to experience the effect of Niacin on % growth rate, cumulative food intake, motor activity and anxiety profile, redox status, 5-HT metabolism and brain histopathology in rats. Rats were administered with Niacin at a dose of 50 mg/ml/kg body weight for 4 weeks following normal diet (ND) and HFD. Behavioral tests were performed after 4 weeks. Animals were sacrificed to collect brain samples. Biochemical, neurochemical and histopathological studies were performed. HFD increased food intake and body weight. The exploratory activity was reduced and anxiety like behavior was observed in HFD treated animals. Activity of antioxidant enzymes was decreased while oxidative stress marker and serotonin metabolism in the brain of rat were increased in HFD treated animals than ND fed rats. Morphology of the brain was also altered by HFD administration. Conversely, Niacin treated animals decreased food intake and % growth rate, increased exploratory activity, produced anxiolytic effects, decreased oxidative stress and increased antioxidant enzyme and 5-HT levels following HFD. Morphology of brain is also normalized by the treatment of Niacin following HFD. In-silico studies showed that Niacin has a potential binding affinity with degradative enzyme of 5-HT i.e. monoamine oxidase (MAO) A and B with an energy of ~ - 4.5 and - 5.0 kcal/mol respectively. In conclusion, the present study showed that Niacin enhanced motor activity, produced anxiolytic effect, and reduced oxidative stress, appetite, growth rate, increased antioxidant enzymes and normalized serotonin system and brain morphology following HFD intake. In-silico studies suggested that increase 5-HT was associated with the binding of MAO with Niacin subsequentially an inhibition of the degradation of monoamine. It is suggested that Niacin has a great antioxidant potential and could be a good therapy for the treatment of HFD induced obesity.

Trace Elements Levels in Major Depressive Disorder-Evaluation of Potential Threats and Possible Therapeutic Approaches

The multifactorial etiology of major depressive disorder (MDD) includes biological, environmental, genetic, and psychological aspects. Recently, there has been an increasing interest in metallomic studies in psychiatry, aiming to evaluate the role of chosen trace elements in the MDD etiology as well as the progression of symptoms. This narrative review aims to summarize the available literature on the relationship between the concentration of chosen elements in the serum of patients with MDD and the onset and progression of this psychiatric condition. The authors reviewed PubMed, Web of Science, and Scopus databases searching for elements that had been investigated so far and further evaluated them in this paper. Ultimately, 15 elements were evaluated, namely, zinc, magnesium, selenium, iron, copper, aluminium, cadmium, lead, mercury, arsenic, calcium, manganese, chromium, nickel, and phosphorus. The association between metallomic studies and psychiatry has been developing dynamically recently. According to the results of current research, metallomics might act as a potential screening tool for patients with MDD while at the same time providing an assessment of the severity of symptoms. Either deficiencies or excessive amounts of chosen elements might be associated with the progression of depressive symptoms or even the onset of the disease among people predisposed to MDD.

Unraveling the Crosstalk between Lipids and NADPH Oxidases in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and a leading cause of end-stage renal disease. Abnormal lipid metabolism and intrarenal accumulation of lipids have been shown to be strongly correlated with the development and progression of diabetic kidney disease (DKD). Cholesterol, phospholipids, triglycerides, fatty acids, and sphingolipids are among the lipids that are altered in DKD, and their renal accumulation has been linked to the pathogenesis of the disease. In addition, NADPH oxidase-induced production of reactive oxygen species (ROS) plays a critical role in the development of DKD. Several types of lipids have been found to be tightly linked to NADPH oxidase-induced ROS production. This review aims to explore the interplay between lipids and NADPH oxidases in order to provide new insights into the pathogenesis of DKD and identify more effective targeted therapies for the disease.

Redox Signaling in Chronic Kidney Disease-Associated Cachexia

Redox signaling alterations contribute to chronic kidney disease (CKD)-associated cachexia. This review aims to summarize studies about redox pathophysiology in CKD-associated cachexia and muscle wasting and to discuss potential therapeutic approaches based on antioxidant and anti-inflammatory molecules to restore redox homeostasis. Enzymatic and non-enzymatic systems of antioxidant molecules have been studied in experimental models of kidney diseases and patients with CKD. Oxidative stress is increased by several factors present in CKD, including uremic toxins, inflammation, and metabolic and hormone alterations, leading to muscle wasting. Rehabilitative nutritional and physical exercises have shown beneficial effects for CKD-associated cachexia. Anti-inflammatory molecules have also been tested in experimental models of CKD. The importance of oxidative stress has been shown by experimental studies in which antioxidant therapies ameliorated CKD and its associated complications in the 5/6 nephrectomy model. Treatment of CKD-associated cachexia is a challenge and further studies are necessary to investigate potential therapies involving antioxidant therapy.

NAD+ Metabolism and Interventions in Premature Renal Aging and Chronic Kidney Disease

Premature aging causes morphological and functional changes in the kidney, leading to chronic kidney disease (CKD). CKD is a global public health issue with far-reaching consequences, including cardio-vascular complications, increased frailty, shortened lifespan and a heightened risk of kidney failure. Dialysis or transplantation are lifesaving therapies, but they can also be debilitating. Currently, no cure is available for CKD, despite ongoing efforts to identify clinical biomarkers of premature renal aging and molecular pathways of disease progression. Kidney proximal tubular epithelial cells (PTECs) have high energy demand, and disruption of their energy homeostasis has been linked to the progression of kidney disease. Consequently, metabolic reprogramming of PTECs is gaining interest as a therapeutic tool. Preclinical and clinical evidence is emerging that NAD⁺ homeostasis, crucial for PTECs' oxidative metabolism, is impaired in CKD, and administration of dietary NAD⁺ precursors could have a prophylactic role against age-related kidney disease. This review describes the biology of NAD⁺ in the kidney, including its precursors and cellular roles, and discusses the importance of NAD⁺ homeostasis for renal health. Furthermore, we provide a comprehensive summary of preclinical and clinical studies aimed at increasing NAD⁺ levels in premature renal aging and CKD.

Effect of Different Levels of Niacin on Serum Biochemical Parameters, Antioxidant Status, Cytokine Levels, Inflammatory Gene Expression and Colonic Microbial Composition in Weaned Piglets

Niacin plays an important role in regulating the gut health of weaned piglets. In this study, 48 25-day-old weaned piglets (7.9 ± 0.20 kg) produced by 14 sows (3 to 4 piglets per sow) were randomly divided into 4 groups with 6 replicates in each group and 2 piglets in each replicate. Each group was fed diets supplemented with 22.5 (N1), 30 (N2), 45 (N3), and 75 (N4) mg/kg of niacin, respectively. Samples were taken at 7 and 14 d, respectively. The study shows that changes in niacin levels significantly affected the content of IgG and IgM in the serum (p < 0.05). Niacin had a significant effect on antioxidant parameters such as MDA, T-SOD, and CuZn-SOD in the jejunal mucosa of weaned piglets (p < 0.05). Moreover, significant differences were observed in the expression of cytokines such as TGF-β, TNF-α, and COX2 in the jejunal mucosa (p < 0.05). The 16S rRNA sequencing analysis showed that there were significant differences in the colonic species composition, which were also accompanied by changes in the isovaleric acid content (p < 0.05). In conclusion, an appropriate increase in niacin dose based on NRC (2012) has an important role in improving the antioxidant status of weaned piglets, alleviating intestinal inflammation in piglets, improving immunity, and regulating the structure of the microbiota.

Phytochemical Screening and Bioactivities of Cactaceae Family Members Endemic to Mexico

Mexico is a center of diversification for the Cactaceae family, with 69% of the species recorded as endemic. Certain members of the Cactaceae family have been chemically analyzed to relate their medicinal use with their phytochemistry. Here, the phytochemistry and bioactivity of ethanol extracts of Ferocactus echidne, F. latispinus, and Mammillaria geminispina were evaluated. A preliminary phytochemical analysis was performed, detecting the presence of saponins, tannins, cardiotonic glycosides, and sesquiterpene lactones. The presence of nicotinic acid in F. echidne and F. latispinus was identified by GC-MS. Other compounds found in the extracts of these three species were gentisic acid, diosmetin, chlorogenic acid, N-methyltyramide, and hordenine. The antioxidant activity was estimated with the DPPH free radical scavenging test. To determine the toxicity of the extracts, the in vivo model of Artemia spp. was used. In addition, the cytotoxicity of the extract was tested on C6, HaCaT, THP-1, and U937 cell lines, while the inflammatory activity was tested by measuring the secretion of cytokines using macrophage cells. The three species showed different bioactivities, including antioxidant, antimicrobial, cytotoxic, and anti-inflammatory activities. To the best of our knowledge, the results presented here are the first described for these species.

Effects of furosemide and tadalafil in both conventional and nanoforms against adenine-induced chronic renal failure in rats

BACKGROUND

Chronic renal failure (CRF) is a progressive loss of renal function that lead to reduced sodium filtration and inappropriate suppression of tubular reabsorption that ultimately leads to volume expansion. The aim of this study was to study the efficacy of furosemide and tadalafil nanoforms compared to conventional forms against adenine-induced CRF rat-model.

METHODS

Addition of 0.75% adenine to the diet of rats for 4 weeks gained general acceptance as a model to study kidney damage as this intervention mimicked most of the structural and functional changes seen in human chronic kidney disease Urine analysis, histopathological changes and immunohistochemical expression of caspase-3 and interleukin-1 beta (IL-1β) in renal tissues were performed.

RESULTS

Our results showed that the combination of tadalafil and furosemide using conventional and nanoparticle formulations had better renoprotective effect than individual drugs. This was demonstrated by improvement of urinary, serum and renal tissue markers as indicative of organ damage. This was also reflected on the reduction of tubular expression of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL). Immunohistochemical studies showed that the deteriorated renal cellular changes indicated by increased expression of caspase-3 and IL-1β were greatly improved by the combined treatment particularly with the nanoforms.

CONCLUSIONS

The nanoforms of both furosemide and tadalafil had greater renopreventive effects compared with conventional forms against adenine-induced CRF in rats.

Oxidative Stress in Ageing and Chronic Degenerative Pathologies: Molecular Mechanisms Involved in Counteracting Oxidative Stress and Chronic Inflammation

Ageing and chronic degenerative pathologies demonstrate the shared characteristics of high bioavailability of reactive oxygen species (ROS) and oxidative stress, chronic/persistent inflammation, glycation, and mitochondrial abnormalities. Excessive ROS production results in nucleic acid and protein destruction, thereby altering the cellular structure and functional outcome. To stabilise increased ROS production and modulate oxidative stress, the human body produces antioxidants, “free radical scavengers”, that inhibit or delay cell damage. Reinforcing the antioxidant defence system and/or counteracting the deleterious repercussions of immoderate reactive oxygen and nitrogen species (RONS) is critical and may curb the progression of ageing and chronic degenerative syndromes. Various therapeutic methods for ROS and oxidative stress reduction have been developed. However, scientific investigations are required to assess their efficacy. In this review, we summarise the interconnected mechanism of oxidative stress and chronic inflammation that contributes to ageing and chronic degenerative pathologies, including neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), cardiovascular diseases CVD, diabetes mellitus (DM), and chronic kidney disease (CKD). We also highlight potential counteractive measures to combat ageing and chronic degenerative diseases.

Exosomes Derived from BM-MSCs Mitigate the Development of Chronic Kidney Damage Post-Menopause via Interfering with Fibrosis and Apoptosis

The rate of chronic kidney disease (CKD) is increasing globally, and it is caused by continuous damage to kidney tissue. With time the renal damage becomes irreversible, leading to CKD development. In females, post-menopause lack of estrogen supply has been described as a risk factor for CKD development, and studies targeting post-menopause CKD are scarce. In the present study, we used exosomes isolated from bone marrow mesenchymal stem/stromal cells (BM-MSCs) to test their therapeutic potential against the development of CKD. At first, the menopause model was achieved by surgical bilateral ovariectomy in female albino rats. After that, 100 µg of exosomes was given to ovariectomized rats, and the study continued for 2 months. Changes in urine volume, urine protein content, kidney function biochemical parameters (creatinine and BUN), kidney antioxidant parameters (SOD, GPx and CAT), histological changes, immunohistochemical levels of caspase 3, and the gene expression of NGAL (related to kidney damage), TGFβ1 and αSMA (related to fibrosis and EMT), and caspase 3 (related to apoptosis) were studied. After the ovariectomy, the occurrence of CKD was confirmed in the rats by the drastic reduction of serum estrogen and progesterone levels, reduced urine output, increased urinary protein excretion, elevated serum creatinine and BUN, reduced GPx SOD, and CAT in kidney tissue, degenerative and fibrotic lesions in the histopathological examination, higher immunohistochemical expression of caspase 3 and increased expression of all studied genes. After exosomes administration, the entire chronic inflammatory picture in the kidney was corrected, and a near-normal kidney structure and function were attained. This study shows for the first time that BM-MSCs exosomes are potent for reducing apoptosis and fibrosis levels and, thus, can reduce the chronic damage of the kidneys in females that are in their menopause period. Therefore, MSCs-derived exosomes should be considered a valuable therapy for preserving postmenopausal kidney structure and function and, subsequently, could improve the quality of females’ life during menopause.

NAD+ and Vascular Dysfunction: From Mechanisms to Therapeutic Opportunities

Nicotinamide adenine dinucleotide (NAD+) is an essential and pleiotropic coenzyme involved not only in cellular energy metabolism, but also in cell signaling, epigenetic regulation, and post-translational protein modifications. Vascular disease risk factors are associated with aberrant NAD+ metabolism. Conversely, the therapeutic increase of NAD+ levels through the administration of NAD+ precursors or inhibitors of NAD+-consuming enzymes reduces chronic low-grade inflammation, reactivates autophagy and mitochondrial biogenesis, and enhances oxidative metabolism in vascular cells of humans and rodents with vascular pathologies. As such, NAD+ has emerged as a potential target for combatting age-related cardiovascular and cerebrovascular disorders. This review discusses NAD+-regulated mechanisms critical for vascular health and summarizes new advances in NAD+ research directly related to vascular aging and disease, including hypertension, atherosclerosis, coronary artery disease, and aortic aneurysms. Finally, we enumerate challenges and opportunities for NAD+ repletion therapy while anticipating the future of this exciting research field, which will have a major impact on vascular medicine.

Association of Serum Triglycerides and Renal Outcomes among 1.6 Million US Veterans

Background

Previous studies have suggested that metabolic syndrome (MetS) components are associated with renal outcomes, defined as a decline in kidney function or reaching end-stage renal disease (ESRD). Elevated triglycerides (TGs) are a component of MetS that have been reported to be associated with renal outcomes. However, the association of TGs with renal outcomes in chronic kidney disease (CKD) patients independent of the other components of the MetS remains understudied.

Methods

We examined 1,657,387 patients with data on TGs and other components of MetS in 2004–2006 and followed up until 2014. Patients with ESRD on renal replacement therapy were excluded. We examined time to ESRD, estimated glomerular filtration rate (eGFR) slope (renal function decline), and time to incident CKD (eGFR <60 mL/min/1.73 m²) among baseline normal kidney function (non-CKD) patients, using Cox or logistic regression, adjusted for clinical characteristics and MetS components. We also stratified analyses by the number of MetS components.

Results

The cohort was on average 64 years old and comprised 5% females, 15% African Americans, and 24% with nondialysis-dependent CKD. Among non-CKD patients, the adjusted relationship of TGs with time to incident CKD was strong and linear. Compared to TGs 120–<160 mg/dL, higher TGs were associated with a faster renal function decline across all CKD stages. Elevated TGs ≥240 mg/dL were associated with a faster time to ESRD among non-CKD and CKD stages 3A–3B, while the risk gradually declined to null or lower in CKD stages 4–5. Models were robust after MetS component adjustment and stratification.

Conclusion

Independent of MetS components, high TGs levels were associated with a higher incidence of CKD and a faster renal function decline, yet showed no or inverse associations with time to ESRD in CKD stages 4–5. Examining the effects of TGs-lowering interventions on incident CKD and kidney preserving therapy warrants further studies including clinical trials.

Mesenchymal stem-cells' exosomes are renoprotective in postmenopausal chronic kidney injury via reducing inflammation and degeneration

Chronic kidney disease (CKD) is an important global disease its rates are increasing worldwide. CKD is caused by injuries to kidney tissue that exceeds the rate of regeneration, which with time lead to irreversible renal damage and CKD become evident. In females, diminished estrogen supply in the postmenopausal period is associated with greater risk for developing CKD. In this study we isolated exosomes from bone marrow mesenchymal stem/stromal cells (BM-MSCs) and tested their therapeutic effects on post-menopause CKD (PM-CKD) and compared their effects with BM-MSCs. The menopause model was achieved by bilateral ovariectomy in 8-months-old female albino rats, then no treatment, 2 million BM-MSCs or 100 μg of exosomes (Exo) was given intravenously in tail vein to ovariectomized rats and the study continued for 8 weeks post-ovariectomy. Changes in weight, urine volume, urine protein content, kidney function biochemical parameters (creatinine and BUN), Kidney oxidative stress (MDA), kidney antioxidant parameters (SOD, GPx and CAT), histopathological changes, immunohistochemical expression of KIM-1 and, finally, genes related to renal damage (peroxiredoxin-3, KIM-1 and ICAM-1) and inflammation (TNF-α, Cox2 and IL-6) were recorded for all study groups. Post-ovariectomy there was an increased body weight, drastic reduction of estrogen and progesterone levels, reduced urine output, increased urinary protein excretion, elevated serum creatinine and BUN, increased MDA and reduced GPx SOD, and CAT in kidney tissue, chronic inflammation, degenerative and fibrotic lesions in histopathological examination, high expression of KIM-1 immunohistochemically and changes in gene expression analyses all pointing to the development of CKD in the study rats. In the PM-CKD groups receiving BM-MSCs or Exo, the whole chronic inflammatory picture was completely reversed towards a much normal kidney structure and function. The improvements were more observable with Exo compared to BM-MSCs. Overall, our results show for the first time that exosomes isolated from BM-MSCs are more potent in reducing chronic inflammatory changes in the kidney of postmenopausal females compared to the cell-based approach using BM-MSCs. Therefore, MSCs-derived exosomes are a promising therapeutic approach for preserving postmenopausal kidney structure and function and, subsequently, should improve the quality of life of postmenopausal females.

Environmental science and pollution research role of heavy metal concentrations and vitamin intake from food in depression: a national cross-sectional study (2009-2017)

Little is known about associations between depression and serum heavy metal levels, dietary vitamin intakes. Thus, we sought to determine the nature of these associations and to predict risks of depression using marginal effects. A data set of 16,371 individuals aged ≥10 years that participated in Korea National Health and Nutrition Examination Surveys (KNHANES) conducted from 2009 to 2017 (excluding 2014 and 2015) was used to obtain information on sociodemographics, family histories, lifestyles, serum heavy metal levels, food intakes, and depression. Serum cadmium (Cd) and lead (Pb) levels were analyzed by graphite furnace atomic absorption spectrometry and mercury (Hg) levels using a mercury analyzer. Daily vitamin intakes were calculated by 24-h dietary recall. The results obtained showed that females are at higher risk of depression than males. A doubling of serum Cd was associated with a 21% increase in depression (AOR 1.21, 95% CI: 1.07-1.37, p = 0.002), whereas twofold increases in daily vitamin B1, B3 and vitamin A intakes reduced the risk of depression by 17% (0.83, 95% CI: 0.73-0.95, p = 0.005), 20% (0.80, 95% CI: 0.70-0.91, p = 0.001), and 8% (0.92, 95% CI: 0.85-0.99, p = 0.020), respectively. Interactions between heavy metals, vitamin intakes, and sex did not influence the risk of depression. The result shows that increased daily dietary vitamin intake might protect the public against depression. Further studies are needed to reduce the risks posed by heavy metals and to determine more comprehensively the effects of daily dietary vitamin intake on depression.

Therapeutic Potential of Emerging NAD+-Increasing Strategies for Cardiovascular Diseases

Cardiovascular diseases are the leading cause of death worldwide. Aging and/or metabolic stress directly impact the cardiovascular system. Over the last few years, the contributions of altered nicotinamide adenine dinucleotide (NAD+) metabolism to aging and other pathological conditions closely related to cardiovascular diseases have been intensively investigated. NAD+ bioavailability decreases with age and cardiometabolic conditions in several mammalian tissues. Compelling data suggest that declining tissue NAD+ is commonly related to mitochondrial dysfunction and might be considered as a therapeutic target. Thus, NAD+ replenishment by either genetic or natural dietary NAD+-increasing strategies has been recently demonstrated to be effective for improving the pathophysiology of cardiac and vascular health in different experimental models, as well as human health, to a lesser extent. Here, we review and discuss recent experimental evidence illustrating that increasing NAD+ bioavailability, particularly by the use of natural NAD+ precursors, may offer hope for new therapeutic strategies to prevent and treat cardiovascular diseases.

Nicotinamide adenine dinucleotide and the sirtuins caution: Pro-cancer functions

This scoping review aims to perform a brief but comprehensive assessment of existing peer-reviewed literature and determine whether raising nicotinamide adenine dinucleotide can prevent or promote tumorigenesis. The examination of extensive peer-reviewed data regarding the synthesis of nicotinamide adenine dinucleotide has been performed with a focus on nuclear dynamics and the deoxyribose nucleic acid repair pathway. Various enzymatic protective functions have been identified from nicotinamide adenine dinucleotide levels, as well as the threat role that is also explored. Nicotinamide adenine dinucleotide precursors and sirtuin-activating compounds are becoming ubiquitous in the commercial market. Further research into whether elevating levels of nicotinamide adenine dinucleotide or overexpression of sirtuins can increase the potential for neoplasm or other age-related pathophysiology is warranted due to the high energy requirements of certain diseases such as cancer.

A network pharmacology-based approach to explore the active ingredients and molecular mechanism of Lei-gong-gen formula granule on a spontaneously hypertensive rat model

Background

Lei-gong-gen formula granule (LFG) is a folk prescription derived from Zhuang nationality, the largest ethnic minority among 56 nationalities in China. It consists of three herbs, namely Eclipta prostrata (L.) L., Smilax glabra Roxb, and Centella asiatica (L.) Urb. It has been widely used as health protection tea for hundreds of years to prevent hypertension in Guangxi Zhuang Autonomous Region. The purpose of this study is to validate the antihypertensive effect of LFG on the spontaneously hypertensive rat (SHR) model, and to further identify the effective components and anti-hypertension mechanism of LFG.

Methods

The effects of LFG on blood pressure, body weight, and heart rate were investigated in vivo using the SHR model. The levels of NO, ANG II, and ET-1 in the serum were measured, and pathological changes in the heart were examined by H&E staining. The main active components of LFG, their corresponding targets, and hypertension associated pathways were discerned through network pharmacology analysis based on the Traditional Chinese Medicine Systems Pharmacology (TCMSP), Traditional Chinese Medicine Integrated Database (TCMID), and the Bioinformatics Analysis Tool for Molecular Mechanism of Traditional Chinese Medicine (BATMAN-TCM). Then the predicted results were further verified by molecular biology experiments such as RT-qPCR and western blot. Additionally, the potential active compounds were predicted by molecular docking technology, and the chemical constituents of LFG were analyzed and identified by UPLC-QTOF/MS technology. Finally, an in vitro assay was performed to investigate the protective effects of potential active compounds against hydrogen peroxide (H₂O₂) induced oxidative damage in human umbilical vein endothelial cells (HUVEC).

Results

LFG could effectively reduce blood pressure and increase serum NO content in SHR model. Histological results showed that LFG could ameliorate pathological changes such as cardiac hypertrophy and interstitial inflammation. From network pharmacology analysis, 53 candidate active compounds of LFG were collected, which linked to 765 potential targets, and 828 hypertension associated targets were retrieved, from which 12 overlapped targets both related to candidate active compounds from LFG and hypertension were screened and used as the potential targets of LFG on antihypertensive effect. The molecular biology experiments of the 12 overlapped targets showed that LFG could upregulate the mRNA and protein expressions of NOS3 and proto-oncogene tyrosine-protein kinase SRC (SRC) in the thoracic aorta. Pathway enrichment analysis showed that the PI3K-AKT signaling pathway was closely related to the expression of NOS3 and SRC. Moreover, western blot results showed that LFG significantly increased the protein expression levels of PI3K and phosphorylated AKT in SHR model, suggesting that LFG may active the PI3K-AKT signaling pathway to decrease hypertension. Molecular docking study further supported that p-hydroxybenzoic acid, cedar acid, shikimic acid, salicylic acid, nicotinic acid, linalool, and histidine can be well binding with NOS3, SRC, PI3K, and AKT. UPLC-QTOF/MS analysis confirmed that p-hydroxybenzoic acid, shikimic acid, salicylic acid, and nicotinic acid existed in LFG. Pre-treatment of HUVEC with nicotinic acid could alleviate the effect on cell viability induced by H₂O₂ and increase the NO level in cell supernatants.

Conclusions

LFG can reduce the blood pressure in SHR model, which might be attributed to increasing the NO level in serum for promoting vasodilation via upregulating SRC expression level and activating the PI3K-AKT-NOS3 signaling pathway. Nicotinic acid might be the potential compound for LFG antihypertensive effect.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00507-1.

Nicotinic Acid against Acetaminophen-Induced Hepatotoxicity via Sirt1/Nrf2 Antioxidative Pathway in Mice

Acetaminophen (N-acetyl-p-aminophenol, APAP) overdose causes hepatotoxicity, even liver failure, and oxidative stress plays pivotal role in its pathogenesis. Nicotinic acid (NA) is one form of vitamin B3, which has been used to treat a series of diseases in clinic for decades. To date, several studies have evidenced that NA has anti-oxidative property. Therefore, NA may have the hepatoprotective potential against APAP-induced toxicity. Here, our aim was to investigate the beneficial effect of NA against hepatotoxicity induced by APAP and its mechanism in vivo. BALB/c mice were intraperitoneally injected with NA (100 mg/kg) 3 times at 24, 12 and 1 h before APAP (600 mg/kg or 400 mg/kg) challenge. The results showed that pretreatment of NA markedly improved the survival rate, alleviated serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and mitigated the histopathological injuries compared to APAP-exposed mice. Furthermore, NA significantly elevated the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) content, while reduced malondialdehyde (MDA) level. Finally, the signaling pathway was probed. The western blot revealed that NA up-regulated Sirtuin1 (Sirt1), nuclear factor erythroid 2-related factor 2 (Nrf2) and NAD(P)H quinone dehydrogenase-1 (NQO-1) expression and down-regulated Kelch-like ECH-associated protein 1 (Keap1) level in liver followed APAP exposure, implying Sirt1/Nrf2 axis exerted an essential role in the protective mechanism of NA on APAP toxicity. In brief, pretreatment of NA effectively protects liver against hepatotoxicity due to overdose of APAP through an antioxidant dependent manner modulated by Sirt1/Nrf2 signaling pathway.

Supplementation with Niacin during in vitro maturation improves the quality of porcine embryos

Niacin, also known as vitamin B3, has a pivotal role in energy metabolism, cellular signaling cascades regulating gene expression, and apoptosis. However, the effect of Niacin on porcine early embryo developmental competence remains to be elucidated. The present study aimed to assess the effects of Niacin treatment during in vitro maturation (IVM) on the nuclear maturation of porcine oocytes and subsequent development of in vitro embryos. In addition, the expression profiles of selected genes related to lipid metabolism, oxidative stress, and apoptosis were assessed. The IVM medium was supplemented with different concentrations of Niacin (0, 300, 600, and 900 μM). The results showed that a high concentration of Niacin (900 μM) significantly decreased cumulus expansion compared to the other groups (p < 0.05). No significant difference was observed among the experimental groups for nuclear maturation rate. Niacin treatments (300, 600, and 900 μM) during IVM significantly (p < 0.05) enhanced glutathione levels. Treatment with 300 and 600 μM significantly (p < 0.05) lowered the reactive oxygen species levels compared to treatment with 900 μM and the control group. Niacin supplementation to the IVM media significantly improved the cleavage and blastocyst rates compared to the control group. Supplementation with 300 and 600 μM of Niacin significantly increased the total cell number of blastocysts compared to supplementation with 900 μM or the control groups. Cytoplasmic lipid droplets were significantly reduced after 600 μM treatment. Supplementation of Niacin to IVM media positively affected the relative expression of genes related to energy and oxidative status (SIRT1), pro-apoptosis (BAX), anti-apoptosis (BCL2), and lipid metabolism (ACACA and PNPLA2) in cumulus cells and oocytes. Taken together, Niacin supplementation to porcine IVM media improved the developmental competence of early embryos mainly through protection against oxidative stress and its influence on energy metabolism and apoptosis pathways.

Jian-Pi-Yi-Shen Formula Ameliorates Oxidative Stress, Inflammation, and Apoptosis by Activating the Nrf2 Signaling in 5/6 Nephrectomized Rats

Chronic kidney disease (CKD) is an increasing global public health problem, with high morbidity and mortality. Jian-Pi-Yi-Shen (JPYS) formula is a representative traditional Chinese medicine formula in the treatment of CKD, which is widely used in clinical practice in China. However, the underlying mechanism has not been well elucidated. In the present study, we measured the markers of apoptosis, inflammation, oxidative stress, and nuclear factor erythroid 2–related factor 2 (Nrf2) signaling to investigate the effects of JPYS formula on renal function and fibrosis and its molecular mechanism in an established animal model of 5/6 nephrectomized (5/6Nx) rats. The results demonstrated that the JPYS formula exerted a significant preventive effect on renal dysfunction and fibrosis, based on analysis of correlative parameters such as urinary protein, SCr, BUN, glomerular sclerosis index, and tubulointerstitial fibrosis score and renal histopathology and ultrastructural pathology of CKD rats. JPYS formula also induced downregulation of gene expression associated with fibrosis, such as TGF-β and type I, III, and IV collagen. Moreover, the JPYS formula showed a significant protective effect in suppressing cell apoptosis according to the results of apoptotic indexes, including increased gene expression of Bcl-2, decreased gene expression of Bax, caspase 3, caspase 9, and the number of TUNEL-positive cells. JPYS formula also ameliorated the activation of the NF-κB-mediated inflammatory pathway, as manifested by the downregulation of gene expression of TNF-α, IL-1β, IκBα, NF-κB p65, MCP-1, CXCL1, COX-2, and iNOS in the kidney. Our evidence also suggested that the JPYS formula ameliorates oxidative stress by promoting antioxidant function according to antioxidant index indicators as an indicator of GSH, SOD, CAT, and GPx and abating excessive accumulation of the reactive oxygen species biomarkers, including ROS, TBARS, 8-oxo-dG, and MDA. The data also suggested that the JPYS formula reversed the downregulation of HO-1 and Nrf2 level and upregulation of Keap1 expression. Together, our data highlighted that the JPYS formula relieved renal oxidative injury mediated by activation of Nrf2 signaling by inhibiting inflammation and apoptosis in CKD rats.

Role of HCA2 in Regulating Intestinal Homeostasis and Suppressing Colon Carcinogenesis

Hydroxycarboxylic acid receptor 2 (HCA₂) is vital for sensing intermediates of metabolism, including β-hydroxybutyrate and butyrate. It also regulates profound anti-inflammatory effects in various tissues, indicating that HCA₂ may serve as an essential therapeutic target for mediating inflammation-associated diseases. Butyrate and niacin, endogenous and exogenous ligands of HCA₂, have been reported to play an essential role in maintaining intestinal homeostasis. HCA₂, predominantly expressed in diverse immune cells, is also present in intestinal epithelial cells (IECs), where it regulates the intricate communication network between diet, microbiota, and immune cells. This review summarizes the physiological role of HCA₂ in intestinal homeostasis and its pathological role in intestinal inflammation and cancer.

Association between alcohol intake and the risk of systemic lupus erythematosus: A systematic review and meta-analysis

OBJECTIVES

Previous studies have reported inconsistent results on the relationship between alcohol intake and the risk of systemic lupus erythematosus (SLE). Therefore, we conducted a systematic review and meta-analysis to illustrate the potential role of alcohol intake on the progression of SLE.

METHODS

An electronic search of the PubMed, EmBase, and the Cochrane library databases was conducted from their inception up to March 2020. Observational studies that investigated the role of alcohol intake on the risk of SLE were eligible for inclusion in this study. The pooled odds ratio (OR) with 95% confidence interval (CI) was calculated as an effect estimate using the random-effects model.

RESULTS

Seven case-control studies (n = 3, 251) and three cohort studies (n = 322, 479) were selected for the final meta-analysis. Mild (OR: 0.85; 95% CI: 0.53-1.38; p = 0.515) or heavy (OR: 0.63; 95% CI: 0.37-1.09; p = 0.102) alcohol intake were not associated with the risk of SLE, while moderate alcohol intake could protect against the risk of SLE (OR: 0.71; 95% CI: 0.55-0.93; p = 0.012). Sensitivity analysis suggested that heavy alcohol intake was associated with a reduced risk of SLE (OR: 0.47; 95% CI: 0.32-0.67; p < 0.001).

CONCLUSIONS

This study found that moderate alcohol intake could protect against the risk of SLE, while mild or heavy alcohol intake did not significantly affect the risk of SLE.

Inflammation and JNK's Role in Niacin-GPR109A Diminished Flushed Effect in Microglial and Neuronal Cells With Relevance to Schizophrenia

Schizophrenia is a neuropsychiatric illness with no single definitive aetiology, making its treatment difficult. Antipsychotics are not fully effective because they treat psychosis rather than the cognitive or negative symptoms. Antipsychotics fail to alleviate symptoms when patients enter the chronic stage of illness. Topical application of niacin showed diminished skin flush in the majority of patients with schizophrenia compared to the general population who showed flushing. The niacin skin flush test is useful for identifying patients with schizophrenia at their ultra-high-risk stage, and understanding this pathology may introduce an effective treatment. This review aims to understand the pathology behind the diminished skin flush response, while linking it back to neurons and microglia. First, it suggests that there are altered proteins in the GPR109A-COX-prostaglandin pathway, inflammatory imbalance, and kinase signalling pathway, c-Jun N-terminal kinase (JNK), which are associated with diminished flush. Second, genes from the GPR109A-COX-prostaglandin pathway were matched against the 128-loci genome wide association study (GWAS) for schizophrenia using GeneCards, suggesting that G-coupled receptor-109A (GPR109A) may have a genetic mutation, resulting in diminished flush. This review also suggests that there may be increased pro-inflammatory mediators in the GPR109A-COX-prostaglandin pathway, which contributes to the diminished flush pathology. Increased levels of pro-inflammatory markers may induce microglial-activated neuronal death. Lastly, this review explores the role of JNK on pro-inflammatory mediators, proteins in the GPR109A-COX-prostaglandin pathway, microglial activation, and neuronal death. Inhibiting JNK may reverse the changes observed in the diminished flush response, which might make it a good therapeutic target.

B Vitamins and Their Role in Immune Regulation and Cancer

B group vitamins represent essential micronutrients for myriad metabolic and regulatory processes required for human health, serving as cofactors used by hundreds of enzymes that carry out essential functions such as energy metabolism, DNA and protein synthesis and other critical functions. B vitamins and their corresponding vitamers are universally essential for all cellular life forms, from bacteria to humans. Humans are unable to synthesize most B vitamins and are therefore dependent on their diet for these essential micronutrients. More recently, another source of B vitamins has been identified which is derived from portions of the 10¹³ bacterial cells inhabiting the gastrointestinal tract. Here we review the expanding literature examining the relationship between B vitamins and the immune system and diverse cancers. Evidence of B vitamin’s role in immune cell regulation has accumulated in recent years and may help to clarify the disparate findings of numerous studies attempting to link B vitamins to cancer development. Much work remains to be carried out to fully clarify these relationships as the complexity of B vitamins’ essential functions complicates an unequivocal assessment of their beneficial or detrimental effects in inflammation and cancers.

Potentials of Musa Species Fruits against Oxidative Stress-Induced and Diet-Linked Chronic Diseases: In Vitro and In Vivo Implications of Micronutritional Factors and Dietary Secondary Metabolite Compounds

Nutritional quality and the well-being of the body system are directly linked aspects of human survival. From the unborn foetus to adulthood, the need for sustainable access to micronutrient-rich foods is pertinent and the global consumption of banana and plantain fruits, in effect, contributes to the alleviation of the scourge of malnutrition. This review is particularly aimed at evaluating the pharmacological dimensions through the biological mechanisms of Musa fruits in the body, which represent correlations with their constituent micronutrient factors and dietary polyphenolic constituents such as minerals, vitamin members, anthocyanins, lutein, α-,β- carotenes, neoxanthins and cryptoxanthins, epi- and gallo catechins, catecholamines, 3-carboxycoumarin, β-sitosterol, monoterpenoids, with series of analytical approaches for the various identified compounds being highlighted therein. Derivative value-products from the compartments (flesh and peel) of Musa fruits are equally highlighted, bringing forth the biomedicinal and nutritional relevance, including the potentials of Musa species in dietary diversification approaches.

Niacin Ameliorates Hepatic Steatosis by Inhibiting De Novo Lipogenesis Via a GPR109A-Mediated PKC-ERK1/2-AMPK Signaling Pathway in C57BL/6 Mice Fed a High-Fat Diet

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. Hepatic de novo lipogenesis (DNL) has been suggested to contribute to the pathogenesis of NAFLD. Recent studies have demonstrated that niacin (NA) modulates hepatic DNL through GPR109A. However, the underlying mechanism remains largely unknown.

OBJECTIVES

This study aims to elucidate the potential molecular mechanism by which GPR109A inhibits hepatic DNL.

METHODS

C57BL/6 wild-type (WT) and Gpr109a knockout (KO) mice (male, 5 wk old) were fed a high-fat diet (60% energy from fat) firstly for 6 wk to generate a diet-induced obese model. Subsequently, they were randomly divided into 4 groups for the next 8-9 wk: WT mice with oral water [WT + vehile (VE)], WT mice with oral NA (50 mM, dissolved in water) (WT + NA), KO mice with oral water (KO + VE), and KO mice with oral NA (50 mM) (KO + NA). Mechanisms were examined in HepG2 cells. Body composition, liver histology, biomarkers of hepatic function, lipid accumulation, and lipid synthesis signals in HepG2 cells were measured.

RESULTS

Upon activation, GPR109A apparently protected against obesity and hepatic steatosis (P < 0.05). The concentrations of hepatic Tnf-α in the WT + NA group were about 50% of those in the WT + VE group (P < 0.05). The activities of serum alanine transaminase and aspartate transaminase were 26.7% and 53.5% lower in the WT + NA group than in the WT + VE group, respectively (P < 0.05). In HepG2 cells, activation of GPR109A resulted in remarkable inhibition of oleic acid-induced lipid accumulation via a protein kinase C-extracellular signal-regulated kinase-1/2-AMP-activated protein kinase signaling pathway.

CONCLUSIONS

NA inhibits hepatic lipogenesis in C57BL/6 mice through a GPR109A-mediated signaling pathway, consistent with the mechanistic studies in HepG2 cells, suggesting its potential for treatment of NAFLD and other fatty liver diseases.

NAD+ homeostasis in health and disease

The conceptual evolution of nicotinamide adenine dinucleotide (NAD⁺) from being seen as a simple metabolic cofactor to a pivotal cosubstrate for proteins regulating metabolism and longevity, including the sirtuin family of protein deacylases, has led to a new wave of scientific interest in NAD⁺. NAD⁺ levels decline during ageing, and alterations in NAD⁺ homeostasis can be found in virtually all age-related diseases, including neurodegeneration, diabetes and cancer. In preclinical settings, various strategies to increase NAD⁺ levels have shown beneficial effects, thus starting a competitive race to discover marketable NAD⁺ boosters to improve healthspan and lifespan. Here, we review the basics of NAD⁺ biochemistry and metabolism, and its roles in health and disease, and we discuss current challenges and the future translational potential of NAD⁺ research.

Niacin in the Central Nervous System: An Update of Biological Aspects and Clinical Applications

Niacin (also known as "vitamin B₃" or "vitamin PP") includes two vitamers (nicotinic acid and nicotinamide) giving rise to the coenzymatic forms nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). The two coenzymes are required for oxidative reactions crucial for energy production, but they are also substrates for enzymes involved in non-redox signaling pathways, thus regulating biological functions, including gene expression, cell cycle progression, DNA repair and cell death. In the central nervous system, vitamin B₃ has long been recognized as a key mediator of neuronal development and survival. Here, we will overview available literature data on the neuroprotective role of niacin and its derivatives, especially focusing especially on its involvement in neurodegenerative diseases (Alzheimer's, Parkinson's, and Huntington's diseases), as well as in other neuropathological conditions (ischemic and traumatic injuries, headache and psychiatric disorders).

Niacin fine-tunes energy homeostasis through canonical GPR109A signaling

The incidence of overweight and obesity has become a global public health problem, constituting a major risk factor for numerous comorbidities. Despite tremendous efforts, effective pharmacological agents for the treatment of obesity are still limited. Here, we showed that in contrast to lactate receptor GPR81, niacin receptor GPR109A-deficient mice had progressive weight gain and hepatic fat accumulation. Using high-fat diet-induced mouse model of obesity, we demonstrated that niacin treatment apparently protected against obesity without affecting food intake in wild-type mice but not in GPR109A-deficient mice. Further investigation showed that niacin treatment led to a remarkable inhibition of hepatic de novo lipogenesis. Additionally, we demonstrated that niacin treatment triggered brown adipose tissue and/or white adipose tissue thermogenic activity via activation of GPR109A. Moreover, we observed that mice exposed to niacin exhibited a dramatic decrease in intestinal absorption of sterols and fatty acids. Taken together, our findings demonstrate that acting on GPR109A, niacin shows the potential to maintain energy homeostasis through multipathways, representing a potential approach to the treatment of obesity, diabetes and cardiovascular disease.-Ye, L., Cao, Z., Lai, X., Wang, W., Guo, Z., Yan, L., Wang, Y., Shi, Y., Zhou, N. Niacin fine-tunes energy homeostasis through canonical GPR109A signaling.

G Protein-Coupled Receptor 109A and Host Microbiota Modulate Intestinal Epithelial Integrity During Sepsis

The intestinal epithelial barrier is important to mucosal immunity, although how it is maintained after damage is unclear. Here, we show that G protein-coupled receptor 109A (GPR109A) supports barrier integrity and decreases mortality in a mouse cecum ligation and puncture (CLP) sepsis model. Data from 16S RNA sequencing showed that the intestinal microbiota of WT and Gpr109a^−/− mice clustered differently and their compositions were disrupted after CLP surgery. GPR109A-deficient mice showed increased mortality, intestinal permeability, altered inflammation, and lower tight junction gene expression. After eliminating the intestinal flora with antibiotics, all experimental mice died within 48 h of CLP surgery. This demonstrates the critical role of the gut microbiota in CLP-induced sepsis. Importantly, mortality and other pathologies in the model were decreased after Gpr109a^−/− mice received WT gut microbiota. These findings indicate that GPR109A regulates the gut microbiota, contributing to intestinal epithelial barrier integrity and decreased mortality in CLP-induced sepsis.

Niacin prevents mitochondrial oxidative stress caused by sub-chronic exposure to methylmercury

Humans and animals can be exposed to different chemical forms of mercury (Hg) in the environment. For example, methylmercury (MeHg)-contaminated fish is part of the basic diet of the riparian population in the Brazilian Amazon Basin, which leads to high total blood and plasma Hg levels in people living therein. Hg induces toxic effects mainly through oxidative stress. Different compounds have been used to prevent the damage caused by MeHg-induced reactive oxygen species (ROS). This study aims to investigate the in vivo effects of sub-chronic exposure to low MeHg levels on the mitochondrial oxidative status and to evaluate the niacin protective effect against MeHg-induced oxidative stress. For this purpose, Male Wistar rats were divided into four groups: control group, treated with drinking water on a daily basis; group exposed to MeHg at a dose of 100 µg/kg/day; group that received niacin at a dose of 50 mg/kg/day in drinking water, with drinking water being administered by gavage; group that received niacin at a dose of 50 mg/kg/day in drinking water as well as MeHg at a dose of 100 µg/kg/day. After 12 weeks, the rats, which weighed 500-550 g, were sacrificed, and their liver mitochondria were isolated by standard differential centrifugation. Sub-chronic exposure to MeHg (100 µg/kg/day for 12 weeks) led to mitochondrial swelling (p < 0.05) and induced ROS overproduction as determined by increased DFCH oxidation (p < 0.05), increased gluthatione oxidation (p < 0.05), and reduced protein thiol content (p < 0.05). In contrast, niacin supplementation inhibited oxidative stress, which counteracted and minimized the toxic MeHg effects on mitochondria.

Sodium Butyrate Inhibits Inflammation and Maintains Epithelium Barrier Integrity in a TNBS-induced Inflammatory Bowel Disease Mice Model

G Protein Coupled Receptor 109A (GPR109A), which belongs to the G protein coupled receptor family, can be activated by niacin, butyrate, and β-hydroxybutyric acid. Here, we assessed the anti-inflammatory activity of sodium butyrate (SB) on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis mice, an experimental model that resembles Crohn's disease, and explored the potential mechanism of SB in inflammatory bowel disease (IBD). In vivo, experimental GPR109a^-/- and wild-type (WT) mice were administered SB (5g/L) in their drinking water for 6weeks. The mice were then administered TNBS via rectal perfusion to imitate colitis. In vitro, RAW246.7 macrophages, Caco-2 cells, and primary peritoneal macrophages were used to investigate the protective roles of SB on lipopolysaccharide (LPS)-induced inflammatory response and epithelium barrier dysfunction. In vivo, SB significantly ameliorated the inflammatory response and intestinal epithelium barrier dysfunction in TNBS-induced WT mice, but failed to provide a protective effect in TNBS-induced GPR109a^-/- mice. In vitro, pre-treatment with SB dramatically inhibited the expression of TNF-α and IL-6 in LPS-induced RAW246.7 macrophages. SB inhibited the LPS-induced phosphorylation of the NF-κB p65 and AKT signaling pathways, but failed to inhibit the phosphorylation of the MAPK signaling pathway. Our data indicated that SB ameliorated the TNBS-induced inflammatory response and intestinal epithelium barrier dysfunction through activating GPR109A and inhibiting the AKT and NF-κB p65 signaling pathways. These findings therefore extend the understanding of GPR109A receptor function and provide a new theoretical basis for treatment of IBD.

The natural compound 2,3,5,4'-tetrahydroxystilbene-2-O-β-d glucoside protects against adriamycin-induced nephropathy through activating the Nrf2-Keap1 antioxidant pathway

2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside (THSG) is an active compound extracted from Polygonum multiflorum Thunb. This herb and radix Polygoni Multiflori preparata have been used to treat arteriosclerosis, hyperlipidemia, hypercholesterolemia, and diabetes for thousands of years. This study aimed to investigate the protective effects of THSG in an Adriamycin (AD)-induced focal segmental glomerulosclerosis (FSGS) mouse model and the underlying mechanisms in an in vitro system. Mice were treated with THSG (2.5 and 10 mg/kg, oral gavage) for 24 consecutive days. On the third day, mice were intravenously given a single dose of AD (10 mg/kg). At the end of the experiment, plasma and kidney samples were harvested to evaluate the therapeutic effects of THSG. The potential mechanisms of THSG in protecting against AD-induced cytotoxicity were examined using a real-time polymerase chain reaction, immunoblots, lactate dehydrogenase assay, and a cellular oxidized-thiol detection system in a mouse mesangial cell line. In this study, THSG showed concentration-dependent protective effects in ameliorating the progression of AD-induced FSGS. THSG suppressed albuminuria and hypercholesterolemia and reduced the status of lipid peroxidation in urine, plasma, and kidney tissue samples. Furthermore, THSG protected against podocyte damage, reduced renal fibrotic gene expressions, and alleviated the severity of glomerulosclerosis. Treatment of mouse mesangial cells with THSG induced nuclear factor erythroid-derived 2-like 2 (Nrf2) nuclear translocation, increased heme oxygenase-1 and NAD(P)H:quinone oxidoreductase (NQO)-1 gene expressions, and reduced cellular thiol oxidation and resistance to AD-induced cytotoxicity. Silencing Nrf2 and its repressor protein, Kelch-like ECH-associated protein 1 (Keap1), abolished these protective effects of THSG. In conclusion, THSG can play a protective role in ameliorating the progression of FSGS in a mouse model through activation of the Nrf2-Keap1 antioxidant pathway. Although a well-designed therapeutic study is needed, THSG may be applied to manage chronic kidney disease.

The Effects of Long-Term Chaetomellic Acid A Administration on Renal Function and Oxidative Stress in a Rat Model of Renal Mass Reduction

Purpose. This study aimed to evaluate the effect of chronic treatment with chaetomellic acid A (CAA) on oxidative stress and renal function in a model of renal mass reduction. Methods. Male Wistar rats were subjected to 5/6 nephrectomy (RMR) or sham-operated (SO). One week after surgery, rats have been divided into four experimental groups: RMR: RMR rats without treatment (n = 14); RMR + CAA: RMR rats treated with CAA (n = 13); SO: SO rats without treatment (n = 13); and SO + CAA: SO rats treated with CAA (n = 13). CAA was intraperitoneally administered in a dose of 0.23 µg/Kg three times a week for six months. Results. RMR was accompanied by a significant reduction in catalase and glutathione reductase (GR) activity (p < 0.05) and a decrease in reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. CAA administration significantly increased catalase and GR activity (p < 0.05) and increased GSH/GSSG ratio, but no significant difference between the treated and nontreated groups was found in this ratio. No significant differences were found between the RMR groups in any of the parameters of renal function. However, CAA administration slightly improves some parameters of renal function. Conclusions. These data suggest that CAA could attenuate 5/6 RMR-induced oxidative stress.

Activated niacin receptor HCA2 inhibits chemoattractant-mediated macrophage migration via Gβγ/PKC/ERK1/2 pathway and heterologous receptor desensitization

The niacin receptor HCA2 is implicated in controlling inflammatory host responses with yet poorly understood mechanistic basis. We previously reported that HCA2 in A431 epithelial cells transduced Gβγ-protein kinase C- and Gβγ-metalloproteinase/EGFR-dependent MAPK/ERK signaling cascades. Here, we investigated the role of HCA2 in macrophage-mediated inflammation and the underlying mechanisms. We found that proinflammatory stimulants LPS, IL-6 and IL-1β up-regulated the expression of HCA2 on macrophages. Niacin significantly inhibited macrophage chemotaxis in response to chemoattractants fMLF and CCL2 by disrupting polarized distribution of F-actin and Gβ protein. Niacin showed a selected additive effect on chemoattractant-induced activation of ERK1/2, JNK and PI3K pathways, but only the MEK inhibitor UO126 reduced niacin-mediated inhibition of macrophage chemotaxis, while activation of ERK1/2 by EGF alone did not inhibit fMLF-mediated migration of HEK293T cells co-expressing HCA2 and fMLF receptor FPR1. In addition, niacin induced heterologous desensitization and internalization of FPR1. Furthermore, niacin rescued mice from septic shock by diminishing inflammatory symptoms and the effect was abrogated in HCA2^-/- mice. These results suggest that Gβγ/PKC-dependent ERK1/2 activation and heterologous desensitization of chemoattractant receptors are involved in the inhibition of chemoattractant-induced migration of macrophages by niacin. Thus, HCA2 plays a critical role in host protection against pro-inflammatory insults.

Pleiotropic effects of niacin: Current possibilities for its clinical use

Niacin was the first hypolipidemic drug to significantly reduce both major cardiovascular events and mortality in patients with cardiovascular disease. Niacin favorably influences all lipoprotein classes, including lipoprotein[a],and belongs to the most potent hypolipidemic drugs for increasing HDL-C. Moreover, niacin causes favorable changes to the qualitative composition of lipoprotein HDL. In addition to its pronounced hypolipidemic action, niacin exerts many other, non-hypolipidemic effects (e.g., antioxidative, anti-inflammatory, antithrombotic), which favorably influence the development and progression of atherosclerosis. These effects are dependent on activation of the specific receptor HCA2. Recent results published by the two large clinical studies, AIM-HIGH and HPS2-THRIVE, have led to the impugnation of niacin's role in future clinical practice. However, due to several methodological flaws in the AIM-HIGH and HPS2-THRIVE studies, the pleiotropic effects of niacin now deserve thorough evaluation. This review summarizes the present and possible future use of niacin in clinical practice in light of its newly recognized pleiotropic effects.

Anti-inflammatory effects of the hydroxycarboxylic acid receptor 2

The hydroxycarboxylic acid receptors (HCA1-3) are a family of G-protein-coupled receptors that are critical for sensing endogenous intermediates of metabolism. All three receptors are predominantly expressed on adipocytes and mediate anti-lipolytic effects. In addition to adipocytes, HCA2 is highly expressed on immune cells, including macrophages, monocytes, neutrophils and dermal dendritic cells, among other cell types. The endogenous ligand for HCA2 is beta-hydroxybutyrate (β-OHB), a ketone body produced by the liver through β-oxidation when an individual is in a negative energy balance. Recent studies demonstrate that HCA2 mediates profound anti-inflammatory effects in a variety of tissues, indicating that HCA2 may be an important therapeutic target for treating inflammatory disease processes. This review summarizes the roles of HCA2 on inflammation in a number of tissues and clinical states.