Niacin, an old drug with a new twist

Exploratory analysis of the association between dietary niacin intakes and nonalcoholic fatty liver disease among US adults: 1999-2018 data analysis from the National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

Previous researches have revealed the potential association between dietary niacin intakes and several diseases, but studies assessing the association between dietary niacin intakes and nonalcoholic fatty liver disease (NAFLD) is limited and remains unclear. This study was performed to explore the association.

METHODS

In this study, 10,528 participants (male: 5,257) in the 10 National Health and Nutrition Examination Survey (NHANES) cycles (1999-2018) from the NHANES database were selected for the analyses. We built three logistic regression models to explore the independent association between dietary niacin intakes and NAFLD and to explore whether such association exists. Finally, a restricted cubic spline model was applied to simulate the potential nonlinear association between dietary niacin intakes and the occurrence of NAFLD.

RESULTS

The result of the fully-adjusted model suggested that ln-transformed dietary niacin intakes were significantly associated with the reduced occurrence of NAFLD. The odd ratio (OR) of the model and its 95% confidence interval (CI) were 0.81 (0.73, 0.90). When taking the lowest quartile as a reference, the level of niacin in the highest quartile was associated with decreased prevalence of NAFLD (OR: 0.76, 95% CI: 0.63, 0.91). The restricted cubic spline plot presented a negative dose-response association between levels of daily niacin consumption and the occurrence of NAFLD (p for nonlinearity = 0.762).

CONCLUSION

According to the results of this study, dietary niacin intakes may have a negative association with NAFLD, and more well-designed cohort studies are required in the future to confirm the obtained finding.

Heterogeneity of diabetic dyslipidemia, data from the NHANES (2011-2016)

Epidemiologic studies have demonstrated that diabetes amplifies the effects of dyslipidemia as a risk factor for cardiovascular disease (CVD). A better understanding of lipid profiles is important for lipid-lowering treatment and reducing cardiovascular risk in populations with diabetes. To describe the dyslipidemia patterns in patient with and without diabetes in the adult US population. Data from National Health and Nutrition Examination Survey (NHANES) 2011 to 2016 was analyzed. Surprisingly, 49.9% of the people with diabetes have both normal triglycerides (TGs) and normal high-density lipoprotein cholesterol (HDL-C). 33.4% of the people with diabetes have elevated TGs and 36.1% of them have low HDL-C. Only 19.3% of them have both elevated TGs and low HDL-C. Among people without diabetes, 67.5% have normal TGs and normal HDL-C, 28.0% have elevated TGs, 23.9% have low HDL-C and 8.8% have both elevated TGs and low HDL-C. The differences in the proportions of individuals with both elevated TGs and low HDL-C between the diabetic group and the nondiabetic group were more obvious in females: 7.7% in women without diabetes and 22.7% in women with diabetes. The proportion of individuals in the TG↑HDL-C↓group in the population with diabetes exhibited a decreasing trend in age groups > 30 years old, and the 30 to 40 years group of individuals with diabetes had the highest proportion of atherogenic dyslipidemia. The low-density lipoprotein cholesterol (LDL-C) to apoB ratio is generally lower in people with diabetes, with the lowest level in the TG↑HDL-C↓group. Dyslipidemia patterns in diabetes patients are highly heterogeneous. Deep phenotyping sub-groups of dyslipidemia is warranted to identify higher-risk patients for evaluation of non-LDL-C therapies. This explained at least partially of the difficult search for novel therapies in the post-LDL-C era.

Drug Therapy for Hypertriglyceridemia and Familial Chylomicronemia Syndrome: Focus on Volnesorsen

Volanesorsen is a new medication that may soon be used in the treatment of hypertriglyceridemia and familial chylomicronemia syndrome (FCS). Volanesorsen works via binding to Apo C-III mRNA and degrading that mRNA, thus decreasing the synthesis of Apo C-III. This decreased synthesis of Apo C-III will increase the binding of triglycerides to LDL receptors and decrease triglyceride plasma levels. It is important to note that currently there are 3 other medication classes available for the treatment of hypertriglyceridemia, including niacin, fish oil/omega-3-fatty acids, and fibrates. However, there are no Food and Drug Administration-approved medications to treat FCS. Recently, volanesorsen was approved in the European Union for the treatment of FCS, but that indication was denied in the United States by the Food and Drug Administration. This was due to the side effects of the drug. Volanesorsen may cause a decrease in platelet count, renal toxicity, and elevate liver enzymes. The current drug regimen for volanesorsen consists of 285 mg once a week by subcutaneous injection, with a recommendation to immediately stop the medication if any of these side effects are noted, to prevent long-term complications. With these side effects reported, fish oil/omega-3-fatty acids seem likely the best choice when it comes to treating hypertriglyceridemia. If FCS is debilitating or greatly affecting the patient's life, then one could recommend volanesorsen. Otherwise, at this time, the side effects of volanesorsen may be too severe to justify its use for mild episodes of FCS or hypertriglyceridemia.

Role of micronutrients in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an autoimmune intestinal disease that includes ulcerative colitis, Crohn's disease, and indeterminate colitis. Patients with IBD are often at risk for malnutrition, including micronutrient deficiencies, due to dietary restrictions and poor intestinal absorption. Micronutrients, including vitamins and minerals, play an important role in the human body's metabolism and maintenance of tissue functions. This article reviews the role of micronutrients in IBD. Micronutrients can affect the occurrence and progression of IBD by regulating immunity, intestinal flora, oxidative stress, intestinal barrier function, and other aspects. Monitoring and timely supplementation of micronutrients are important to delay progression and improve clinical symptoms in IBD patients.

Hyperlipoproteinemia (a) and Phytoestrogen Therapy in Dialysis Patients: A Review

PURPOSE

Hyperlipoproteinemia (a) is a prevalent complication in dialysis patients, with no valid treatment strategy. The aim of this narrative review was to investigate the clinical significance of hyperlipoproteinemia (a) and phytoestrogen therapy in dialysis patients.

METHODS

A comprehensive literature search of the published data was performed regarding the effects of phytoestrogen therapy on hyperlipoproteinemia (a) in dialysis patients.

FINDINGS

Hyperlipoproteinemia (a) occurs in dialysis patients due to decreased catabolism and increased synthesis of lipoprotein (a) [Lp(a)]. A few clinical trials have studied the effects of phytoestrogens on serum Lp(a). All studies of dialysis patients or nonuremic individuals with hyperlipoproteinemia (a), except one, showed that phytoestrogens could significantly reduce serum Lp(a) levels. However, all investigations of phytoestrogen therapy in individuals with normal serum Lp(a) levels showed that it had no effect on serum Lp(a). Phytoestrogens seem to have effects similar to those of estrogen in lowering Lp(a) concentrations.

IMPLICATIONS

Considering the high prevalence of hyperlipoproteinemia (a) in dialysis patients, phytoestrogen therapy is a reasonable approach for reducing serum Lp(a) levels and its complications in these patients.

Relationship Between Vitamins and Diabetes

This review article aims to examine the relationship between specific vitamins and type 2 diabetes. Individuals with diabetes have been observed to have lower levels of specific antioxidant vitamins such as A, C, and E, possibly due to the need to manage oxidative stress caused by glucose metabolic abnormalities. Retinol-binding protein, which has adipocytokine activities, has a modulatory effect. Levels of thiamine, pyridoxine, and biotin are also lower in individuals with diabetes. While the reasons for this are unclear, some improvement in metabolic control has been observed with supplementation. Although metformin is the preferred treatment for type 2 diabetes, it has been found to limit the absorption of certain nutrients, including vitamin B9 and vitamin B12, necessitating regular supplementation of these nutrients for people with diabetes. Diabetes and its consequences, including cardiovascular disease, are more likely in those with low vitamin D levels. Although some research suggests that vitamin K intake may improve glucose metabolism, further evidence is required. Research on the effectiveness of multivitamins has produced inconsistent results, and there are no clear guidelines for vitamin supplementation in individuals with type 2 diabetes mellitus. However, people who use metformin for extended periods may benefit from additional folic acid and vitamin B12 supplements.

Very low HDL levels: clinical assessment and management

In individuals with very low high-density lipoprotein (HDL-C) cholesterol, such as Tangier disease, LCAT deficiency, and familial hypoalphalipoproteinemia, there is an increased risk of premature atherosclerosis. However, analyzes based on comparisons of populations with small variations in HDL-C mediated by polygenic alterations do not confirm these findings, suggesting that there is an indirect association or heterogeneity in the pathophysiological mechanisms related to the reduction of HDL-C. Trials that evaluated some of the HDL functions demonstrate a more robust degree of association between the HDL system and atherosclerotic risk, but as they were not designed to modify lipoprotein functionality, there is insufficient data to establish a causal relationship. We currently have randomized clinical trials of therapies that increase HDL-C concentration by various mechanisms, and this HDL-C elevation has not independently demonstrated a reduction in the risk of cardiovascular events. Therefore, this evidence shows that (a) measuring HDL-C as a way of estimating HDL-related atheroprotective system function is insufficient and (b) we still do not know how to increase cardiovascular protection with therapies aimed at modifying HDL metabolism. This leads us to a greater effort to understand the mechanisms of molecular action and cellular interaction of HDL, completely abandoning the traditional view focused on the plasma concentration of HDL-C. In this review, we will detail this new understanding and the new horizon for using the HDL system to mitigate residual atherosclerotic risk.

The niacin receptor HCAR2 modulates microglial response and limits disease progression in a mouse model of Alzheimer's disease

Increased dietary intake of niacin has been correlated with reduced risk of Alzheimer's disease (AD). Niacin serves as a high-affinity ligand for the receptor HCAR2 (GPR109A). In the brain, HCAR2 is expressed selectively by microglia and is robustly induced by amyloid pathology in AD. The genetic inactivation of Hcar2 in 5xFAD mice, a model of AD, results in impairment of the microglial response to amyloid deposition, including deficits in gene expression, proliferation, envelopment of amyloid plaques, and uptake of amyloid-β (Aβ), ultimately leading to exacerbation of amyloid burden, neuronal loss, and cognitive deficits. In contrast, activation of HCAR2 with an FDA-approved formulation of niacin (Niaspan) in 5xFAD mice leads to reduced plaque burden and neuronal dystrophy, attenuation of neuronal loss, and rescue of working memory deficits. These data provide direct evidence that HCAR2 is required for an efficient and neuroprotective response of microglia to amyloid pathology. Administration of Niaspan potentiates the HCAR2-mediated microglial protective response and consequently attenuates amyloid-induced pathology, suggesting that its use may be a promising therapeutic approach to AD that specifically targets the neuroimmune response.

Regulation of NAD+ metabolism in aging and disease

More than a century after discovering NAD⁺, information is still evolving on the role of this molecule in health and diseases. The biological functions of NAD⁺ and NAD⁺ precursors encompass pathways in cellular energetics, inflammation, metabolism, and cell survival. Several metabolic and neurological diseases exhibit reduced tissue NAD⁺ levels. Significantly reduced levels of NAD⁺ are also associated with aging, and enhancing NAD⁺ levels improved healthspan and lifespan in animal models. Recent studies suggest a causal link between senescence, age-associated reduction in tissue NAD⁺ and enzymatic degradation of NAD⁺. Furthermore, the discovery of transporters and receptors involved in NAD⁺ precursor (nicotinic acid, or niacin, nicotinamide, and nicotinamide riboside) metabolism allowed for a better understanding of their role in cellular homeostasis including signaling functions that are independent of their functions in redox reactions. We also review studies that demonstrate that the functional effect of niacin is partially due to the activation of its cell surface receptor, GPR109a. Based on the recent progress in understanding the mechanism and function of NAD⁺ and NAD⁺ precursors in cell metabolism, new strategies are evolving to exploit these molecules' pharmacological potential in the maintenance of metabolic balance.

Food supplement vitamins, minerals, amino-acids, fatty acids, phenolic and alkaloid-based substances: An overview of their interaction with drugs

Food supplements are a widespread group of products ingested as a diet complement, whose consumption has recently skyrocketed due to the consumers' concern with their well-being. Among food supplements, vitamin- and mineral-based ones are the top sellers, and the demand of others, such as those containing polyphenols, is increasing. Owing to their alleged natural characteristics, consumers take the safety of food supplements for granted, and use them even when taking medicines. Thus, their potential interactions with drugs have been sparsely evaluated. This manuscript aims to bring forth an up-to-date overview of the most important knowledge involving the interactions between food supplements and drugs, relevant to be aware by nutritionists and other healthcare professionals. To this end, an extensive bibliographic review was conducted focusing on peer reviewed data from experimental in vivo evidence and clinical studies whenever major clinical interactions have been reported. Elder people and polymedicated or chronic patients are especially vulnerable to the therapeutic ineffectiveness and toxicity caused by these types of interactions. Drugs used to treat cardiovascular, autoimmune, nervous, and oncological diseases are commonly involved in important clinical interactions with food supplements, many with a narrow therapeutic margin.

Short-term effects induced by nicotinamide in ovariectomized females

Nicotinamide adenine dinucleotide (NAD)+ precursors such as nicotinamide activate sirtuins and enhance energy metabolism. The aim of this study was to evaluate the metabolic effects of nicotinamide in ovariectomized (OVX) female rats to establish molecular targets against obesity, which support the safe therapeutic application of nicotinamide. The OVX animals were divided into groups: SHAM (simulated surgery), SHAMn (two weeks of 35 mg·kg-1 nicotinamide per day, by gavage), OVX, and OVXn (two weeks of 35 mg·kg-1 nicotinamide per day, by gavage). The results indicated that nicotinamide favored lipolysis, as evidenced by an increase in free fatty acid and hepatic triglyceride levels, which were not fully normalized during the treatment period. The lipolysis appeared to be due to increased SIRT1 and mitochondrial oxidative phosphorylation in muscle and adipose tissue. There were decreases in muscle and fat nicotinamide N-methyltransferase (NNMT), which were associated with decreases in mass and triglyceride, low-density lipoprotein cholesterol (LDLc), and total cholesterol content. Nicotinamide appeared to be beneficial for the glycemic profile, with normal hepatic glycogen storage and a tendency towards insulin sensitivity in the OVXn. In the SHAMn group, nicotinamide led to glucose intolerance, together with reduced muscle expressions of nicotinamide phosphoribosyltransferase (NAMPT) and SIRT3, suggesting that there were no short-term benefits. Supplementation with nicotinamide led to tissue-specific adaptive lipid and molecular changes in OVX rats.

Consensus Statement by the American Association of Clinical Endocrinologists and American College of Endocrinology on the Management of Dyslipidemia and Prevention of Cardiovascular Disease Algorithm - 2020 Executive Summary

The treatment of lipid disorders begins with lifestyle therapy to improve nutrition, physical activity, weight, and other factors that affect lipids. Secondary causes of lipid disorders should be addressed, and pharmacologic therapy initiated based on a patient's risk for atherosclerotic cardiovascular disease (ASCVD). Patients at extreme ASCVD risk should be treated with high-intensity statin therapy to achieve a goal low-density lipoprotein cholesterol (LDL-C) of <55 mg/dL, and those at very high ASCVD risk should be treated to achieve LDL-C <70 mg/dL. Treatment for moderate and high ASCVD risk patients may begin with a moderate-intensity statin to achieve an LDL-C <100 mg/dL, while the LDL-C goal is <130 mg/dL for those at low risk. In all cases, treatment should be intensified, including the addition of other LDL-C-lowering agents (i.e., proprotein convertase subtilisin/kexin type 9 inhibitors, ezetimibe, colesevelam, or bempedoic acid) as needed to achieve treatment goals. When targeting triglyceride levels, the desirable goal is <150 mg/dL. Statin therapy should be combined with a fibrate, prescription-grade omega-3 fatty acid, and/or niacin to reduce triglycerides in all patients with triglycerides ≥500 mg/dL, and icosapent ethyl should be added to a statin in any patient with established ASCVD or diabetes with ≥2 ASCVD risk factors and triglycerides between 135 and 499 mg/dL to prevent ASCVD events. Management of additional risk factors such as elevated lipoprotein(a) and statin intolerance is also described.

GPR109A mediates the effects of hippuric acid on regulating osteoclastogenesis and bone resorption in mice

The G protein-coupled receptor 109 A (GPR109A) is robustly expressed in osteoclastic precursor macrophages. Previous studies suggested that GPR109A mediates effects of diet-derived phenolic acids such as hippuric acid (HA) and 3-(3-hydroxyphenyl) propionic acid (3-3-PPA) on promoting bone formation. However, the role of GPR109A in metabolic bone homeostasis and osteoclast differentiation has not been investigated. Using densitometric, bone histologic and molecular signaling analytic methods, we uncovered that bone mass and strength were significantly higher in tibia and spine of standard rodent diet weaned 4-week-old and 6-month-old GPR109A gene deletion (GPR109A-/-) mice, compared to their wild type controls. Osteoclast numbers in bone and in ex vivo bone marrow cell cultures were significantly decreased in GPR109A-/- mice compared to wild type controls. In accordance with these data, CTX-1 in bone marrow plasma and gene expression of bone resorption markers (TNFα, TRAP, Cathepsin K) were significantly decreased in GPR109A-/- mice, while on the other hand, P1NP was increased in serum from both male and female GPR109A-/- mice compared to their respective controls. GPR109A deletion led to suppressed Wnt/β-catenin signaling in osteoclast precursors to inhibit osteoclast differentiation and activity. Indeed, HA and 3-3-PPA substantially inhibited RANKL-induced GPR109A expression and Wnt/β-catenin signaling in osteoclast precursors and osteoclast differentiation. Resultantly, HA significantly inhibited bone resorption and increased bone mass in wild type mice, but had no additional effects on bone in GPR109A-/- mice compared with their respective untreated control mice. These results suggest an important role for GPR109A during osteoclast differentiation and bone resorption mediating effects of HA and 3-3-PPA on inhibiting bone resorption during skeletal development.

Increased cardiovascular risk associated with hyperlipoproteinemia (a) and the challenges of current and future therapeutic possibilities

Population, genetic, and clinical studies demonstrated a causative and continuous, from other plasma lipoproteins independent relationship between elevated plasma lipoprotein (a) [Lp(a)] concentration and the development of cardiovascular disease (CVD), mainly those related to athe-rosclerotic CVD, and calcific aortic stenosis. Currently, a strong international consensus is still lacking regarding the single value which would be commonly used to define hyperlipoproteinemia (a). Its prevalence in the general population is estimated to be in the range of 10%–35% in accordance with the most commonly used threshold levels (>30 or >50 mg/dL). Since elevated Lp(a) can be of special importance in patients with some genetic disorders, as well as in individuals with otherwise controlled major risk factors, the identification and establishment of the proper therapeutic interventions that would lower Lp(a) levels and lead to CVD risk reduction could be very important. The majority of the classical lipid-lowering agents (statins, ezetimibe, and fibrates), as well as nutraceuticals (CoQ10 and garlic), appear to have no significant effect on its plasma levels, whereas for the drugs with the demonstrated Lp(a)-lowering effects (aspirin, niacin, and estrogens), their clinical efficacy in reducing cardiovascular (CV) events has not been unequivocally proven yet. Both Lp(a) apheresis and proprotein convertase subtilisin/kexin type 9 inhibitors can reduce the plasma Lp(a) by approximately 20%–30% on average, in parallel with much larger reduction of low-density lipoprotein cholesterol (up to 70%), what puts us in a difficulty to conclude about the true contribution of lowered Lp(a) to the reduction of CV events. The most recent advancement in the field is the introduction of the novel apolipoprotein (a) [apo(a)] antisense oligonucleotide therapy targeting apo(a), which has already proven itself as being very effective in decreasing plasma Lp(a) (by even >90%), but should be further tested in clinical trials. The aim of this review was to present some of the most important accessible scientific data, as well as dilemmas related to the currently and potentially in the near future more widely available therapeutic options for the management of hyperlipoproteinemia (a).

Early diagnosis and treatment of familial hypercholesterolemia

If undiagnosed and untreated, familial hypercholesterolemia can lead to serious cardiac complications, such as premature atherosclerotic cardiovascular disease. NPs should be familiar with the clinical presentation of this inherited metabolic disease to diagnose patients as early as possible and promptly begin treatment that may include lifestyle changes, statin therapy, and/or nonstatin therapy.

Water Soluble Vitamins and their Role in Diabetes and its Complications

BACKGROUND

Diabetes is a metabolic disorder associated with abnormally high levels of glucose in the blood due to inadequate production of insulin or inadequate sensitivity of cells to the action of insulin. Diabetes has become an increasing challenge in the world. The predicted diabetic population according to the World Health Organization is 8.7% between the age group 20-70 years. There are many complications linked to prolonged high blood glucose levels, such as microvascular complications and macrovascular complications. Vitamins play an important role in glucose metabolism and the potential utility of supplementation is relevant for the prevention and/or management of diabetes mellitus and its complications.

METHODS

Literature search was performed using various dataset like PUBMED, EBSCO, ProQuest, Scopus and selected websites like the National Institute of Health and the World Health Organization.

RESULT

Water-soluble vitamins have been thoroughly studied for their activity in diabetes and diabetic complications.

CONCLUSION

Water-soluble vitamins like B1, B3, B6, B7, B9 and B12 have notable effects in diabetes mellitus and its related complications like nephropathy, neuropathy, retinopathy and cardiomyopathy.

Therapeutic management of hyperlipoproteinemia (a)

Cardiovascular disease (CVD) has consistently been the leading cause of death worldwide. Several clinical and epidemiological studies have demonstrated that an elevated plasma concentration of lipoprotein (a) [Lp(a)] is a causative and independent major risk factor for the development of CVD, as well as calcific aortic valve stenosis. Thus, the therapeutic management of hyperlipoproteinemia (a) has received much attention, as significant reductions in Lp(a) levels may, potentially, favorably affect cardiovascular risk. Aspirin, niacin, estrogens, and statins, which act on different molecular pathways, may be prescribed to patients with mild or modest elevations of Lp(a) levels. Other therapeutic interventions, such as proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, Lp(a) apheresis, and the novel antisense oligonucleotides APO(a)-Rx and APO(a)-LRx, which are being evaluated in ongoing clinical trials, have provided some promising results and can potentially be used in severe cases of hyperlipoproteinemia (a). This review aims to present and discuss the current clinical and scientific data pertaining to the therapeutic options for the management of hyperlipoproteinemia (a).

Gemcabene, a First-in-Class Hypolipidemic Small Molecule in Clinical Development, Attenuates Osteoarthritis and Pain in Animal Models of Arthritis and Pain

Our clinical studies have demonstrated that gemcabene, a small molecule in late-stage clinical development, lowers pro-inflammatory acute-phase protein, C-reactive protein (CRP). This observation was further confirmed in a cell-based study showing inhibition of cytokine-induced CRP production. Based on these observations, in the present study, we tested the hypothesis that gemcabene may possess anti-inflammatory activities in animal models of inflammatory disease. Efficacy of gemcabene was investigated in rat models of carrageenan-induced thermal hyperalgesia (CITH), monosodium iodoacetate (MIA)-induced osteoarthritis (OA), and IL-6/IL-6sR-induced inflammation. We also evaluated efficacy of gemcabene in collagen antibody-induced joint swelling and arthritis in BALB/c mice. In CITH rat model, gemcabene administration attenuated paw withdrawal latency (60% at 30 mg/kg/d and 97% at 100 mg/kg/d) and showed improvement in joint swelling (-50% at 30 mg/kg/d) in MIA model of OA. These findings were further corroborated by IL-6/IL-6sR knee injection model in rat, showing 63 and 71% reduction in hind paw weight distribution at 10 and 30 mg/kg/d doses, respectively. In mouse model of monoclonal antibody-induced arthritis, a dose-dependent attenuation of joint swelling was observed. These results demonstrate that the anti-inflammatory activity of gemcabene previously observed in cell-based and in clinical studies also occurred in animal models of inflammation-induced arthritis and hyperalgesia. Thus, in addition to hypolipidemic efficacy, the anti-inflammatory activity of gemcabene may have additional benefits to patients with elevated vascular inflammation.

Pyridostigmine protects against cardiomyopathy associated with adipose tissue browning and improvement of vagal activity in high-fat diet rats

Obesity, a major contributor to the development of cardiovascular diseases, is associated with an autonomic imbalance characterized by sympathetic hyperactivity and diminished vagal activity. Vagal activation plays important roles in weight loss and improvement of cardiac function. Pyridostigmine is a reversible acetylcholinesterase inhibitor, but whether it ameliorates cardiac lipid accumulation and cardiac remodeling in rats fed a high-fat diet has not been determined. This study investigated the effects of pyridostigmine on high-fat diet-induced cardiac dysfunction and explored the potential mechanisms. Rats were fed a normal or high-fat diet and treated with pyridostigmine. Vagal discharge was evaluated using the BL-420S system, and cardiac function by echocardiograms. Lipid deposition and cardiac remodeling were determined histologically. Lipid utility was assessed by qPCR. A high-fat diet led to a significant reduction in vagal discharge and lipid utility and a marked increase in lipid accumulation, cardiac remodeling, and cardiac dysfunction. Pyridostigmine improved vagal activity and lipid metabolism disorder and cardiac remodeling, accompanied by an improvement of cardiac function in high-fat diet-fed rats. An increase in the browning of white adipose tissue in pyridostigmine-treated rats was also observed and linked to the expression of UCP-1 and CIDEA. Additionally, pyridostigmine facilitated activation of brown adipose tissue via activation of the SIRT-1/AMPK/PGC-1α pathway. In conclusion, a high-fat diet resulted in cardiac lipid accumulation, cardiac remodeling, and a significant decrease in vagal discharge. Pyridostigmine ameliorated cardiomyopathy, an effect related to reduced cardiac lipid accumulation, and facilitated the browning of white adipose tissue while activating brown adipose tissue.

Niacin ameliorates ulcerative colitis via prostaglandin D2-mediated D prostanoid receptor 1 activation

Niacin, as an antidyslipidemic drug, elicits a strong flushing response by release of prostaglandin (PG) D₂. However, whether niacin is beneficial for inflammatory bowel disease (IBD) remains unclear. Here, we observed niacin administration‐enhanced PGD₂ production in colon tissues in dextran sulfate sodium (DSS)‐challenged mice, and protected mice against DSS or 2,4,6‐trinitrobenzene sulfonic acid (TNBS)‐induced colitis in D prostanoid receptor 1 (DP1)‐dependent manner. Specific ablation of DP1 receptor in vascular endothelial cells, colonic epithelium, and myeloid cells augmented DSS/TNBS‐induced colitis in mice through increasing vascular permeability, promoting apoptosis of epithelial cells, and stimulating pro‐inflammatory cytokine secretion of macrophages, respectively. Niacin treatment improved vascular permeability, reduced apoptotic epithelial cells, promoted epithelial cell update, and suppressed pro‐inflammatory gene expression of macrophages. Moreover, treatment with niacin‐containing retention enema effectively promoted UC clinical remission and mucosal healing in patients with moderately active disease. Therefore, niacin displayed multiple beneficial effects on DSS/TNBS‐induced colitis in mice by activation of PGD₂/DP1 axis. The potential efficacy of niacin in management of IBD warrants further investigation.

Niacin Promotes Cardiac Healing after Myocardial Infarction through Activation of the Myeloid Prostaglandin D2 Receptor Subtype 1

Niacin is a well established drug used to lower cholesterol and prevent cardiovascular disease events. However, niacin also causes cutaneous flushing side effects due to release of the proresolution mediator prostaglandin D2 (PGD2). Recent randomized clinical trials have demonstrated that addition of niacin with laropiprant [a PGD2 receptor subtype 1 (DP1) blocker] to statin-based therapies does not significantly decrease the risk of cardiovascular disease events, but increases the risk of serious adverse events. Here, we tested whether, and how, niacin beneficial effects on myocardial ischemia require the activation of the PGD2/DP1 axis. Myocardial infarction (MI) was reproduced by ligation of the left anterior descending branch of the coronary artery in mice. We found that niacin increased PGD2 release in macrophages and shifted macrophages to M2 polarization both in vitro and in vivo by activation of DP1 and accelerated inflammation resolution in zymosan-induced peritonitis in mice. Moreover, niacin treatment facilitated wound healing and improved cardiac function after MI through DP1-mediated M2 bias and timely resolution of inflammation in infarcted hearts. In addition, we found that niacin intake also stimulated M2 polarization of peripheral monocytes in humans. Collectively, niacin promoted cardiac functional recovery after ischemic myocardial infarction through DP1-mediated M2 polarization and timely resolution of inflammation in hearts. These results indicated that DP1 inhibition may attenuate the cardiovascular benefits of niacin.

Impact of cholesterol on disease progression

Cholesterol-rich microdomains (also called lipid rafts), where platforms for signaling are provided and thought to be associated with microbe-induced pathogenesis and lead to cancer progression. After treatment of cells with cholesterol disrupting or usurping agents, raft-associated proteins and lipids can be dissociated, and this renders the cell structure nonfunctional and therefore mitigates disease severity. This review focuses on the role of cholesterol in disease progression including cancer development and infectious diseases. Understanding the molecular mechanisms of cholesterol in these diseases may provide insight into the development of novel strategies for controlling these diseases in clinical scenarios.

Vitamins and type 2 diabetes mellitus

The present review evaluates the relationship between type 2 diabetes mellitus and individual or combined vitamins. Antioxidant vitamins A, C and E are found decreased in diabetic subjects, possibly due to an increased need to control the excessive oxidative stress produced by abnormalities in glucose metabolism. On the other hand, retinol binding protein exerts a modulating effect, as it has adipokine functions. With respect to the B group vitamins, thiamin, pyridoxine and biotin have been found decreased but the mechanisms are not clear, however supplementation has shown some improvement of the metabolic control in diabetic patients. The absorption of folic acid and vitamin B12 is importantly decreased by the prolongued use of metformin, which is the first choice drug in uncomplicated diabetes, thus these two nutrients have been found deficient in the disease and most probably need to be supplemented regularly. On the other hand, vitamin D is considered a risk factor for the development of diabetes as well as its complications, particularly cardiovascular ones. Although some studies have found an association of vitamin K intake with glucose metabolism further research is needed. Studies on the use of multivitamin supplements have shown unconclusive results. After reviewing the evidence, no real recommendation on the use of vitamin supplements in type 2 diabetes mellitus can be issued, however patients using metformin during prolongued periods may need folic acid and vitamin B12.

High-density lipoproteins in the prevention of cardiovascular disease: changing the paradigm

High-density-lipoprotein cholesterol (HDL-C) has been identified in population studies as an independent inverse predictor of cardiovascular events. Although the causal nature of this association has been questioned, HDL and its major protein, apolipoprotein (apo)A1, have been shown to prevent and reverse atherosclerosis in animal models. In addition, HDL and apoA1 have several putatively atheroprotective functions, such as the ability to promote efflux of cholesterol from macrophages in the artery wall, inhibit vascular inflammation, and enhance endothelial function. Therefore, HDL-C and apoA1 have been investigated as therapeutic targets for coronary heart disease. However, recent clinical trials with drugs that raise HDL-C, such as niacin and inhibitors of cholesteryl ester transfer protein, have been disappointing. Here, we review the current state of the science regarding HDL as a therapeutic target.

Testing cardiovascular drug safety and efficacy in randomized trials

Randomized trials provide the gold standard evidence on which rests the decision to approve novel therapeutics for clinical use. They are large and expensive and provide average but unbiased estimates of efficacy and risk. Concern has been expressed about how unrepresentative populations and conditions that pertain in randomized trials might be of the real world, including concerns about the homogeneity of the biomedical and adherence characteristics of volunteers entered into such trials, the dose and constancy of drug administration and the mixture of additional medications that are restricted in such trials but might influence outcome in practice. A distinction has been drawn between trials that establish efficacy and those that demonstrate effectiveness, drugs that patients actually consume in the real world for clinical benefit. However, randomized controlled trials remain the gold standard for establishing efficacy and the testing of effectiveness with less rigorous approaches is a secondary, albeit important consideration. Despite this, there is an appreciation that average results may conceal considerable interindividual variation in drug response, leading to a failure to appreciate clinical value or risk in subsets of patients. Thus, attempts are now being made to individualize risk estimates by modulating those derived from large randomized trials with the individual baseline risk estimates based on demographic and biological criteria-the individual Numbers Needed to Treat to obtain a benefit, such as a life saved. Here, I will consider some reasons why large phase 3 trials-by far the most expensive element of drug development-may fail to address the unmet medical needs, which should justify such effort and investment.

High-density lipoprotein and atherosclerosis regression: evidence from preclinical and clinical studies

High-density lipoprotein (HDL) particles transport (among other molecules) cholesterol (HDL-C). In epidemiological studies, plasma HDL-C levels have an inverse relationship to the risk of atherosclerotic cardiovascular disease. It has been assumed that this reflects the protective functions of HDL, which include their ability to promote cholesterol efflux. Yet, several recent pharmacological and genetic studies have failed to demonstrate that increased plasma levels of HDL-C resulted in decreased cardiovascular disease risk, giving rise to a controversy regarding whether plasma levels of HDL-C reflect HDL function, or that HDL is even as protective as assumed. The evidence from preclinical and (limited) clinical studies shows that HDL can promote the regression of atherosclerosis when the levels of functional particles are increased from endogenous or exogenous sources. The data show that regression results from a combination of reduced plaque lipid and macrophage contents, as well as from a reduction in its inflammatory state. Although more research will be needed regarding basic mechanisms and to establish that these changes translate clinically to reduced cardiovascular disease events, that HDL can regress plaques suggests that the recent trial failures do not eliminate HDL from consideration as an atheroprotective agent but rather emphasizes the important distinction between HDL function and plasma levels of HDL-C.