Niacin and Selenium Attenuate Sepsis-Induced Lung Injury by Up-Regulating Nuclear Factor Erythroid 2-Related Factor 2 Signaling

Meta-analysis of niacin and NAD metabolite treatment in infectious disease animal studies suggests benefit but requires confirmation in clinically relevant models

Disruption of nicotinamide adenine dinucleotide (NAD) biosynthesis and function during infection may impair host defenses and aggravate inflammatory and oxidative organ injury. Increasingly, studies are investigating whether niacin or NAD metabolite treatment is beneficial in infection and sepsis animal models. We examined whether this preclinical experience supports clinical trials. A systematic review of three data bases was conducted through 2/29/2024 and a meta-analysis was performed comparing niacin or NAD metabolite treatment to control in adult animal models employing microbial challenges. Fifty-six studies met inclusion criteria, with 24 published after 2019. Most studies employed mouse (n = 40 studies) or rat (n = 12) models and administered either a bacterial toxin (n = 28) or bacterial (n = 19) challenge. Four and three studies employed viral or fungal challenges respectively. Studies investigated an NAD metabolite alone (n = 44), niacin alone (n = 9), or both (n = 3), usually administered before or within 24h after challenge (n = 50). Only three and four studies included standard antimicrobial support or started treatment > 24h after challenge respectively. In similar patterns with differing animal types (p ≥ 0.06), compared to control across those studies investigating the parameter, niacin or NAD treatment decreased the odds ratio of mortality [95% confidence interval (CI)] [0.28 (0.17, 0.49)] and in blood or tissue increased antioxidant levels [standardized mean differences (95%CI)] (SMD) [3.61 (2.20,5.02)] and decreased levels of microbes [- 2.44 (- 3.34, - 1.55)], histologic and permeability organ injury scoring [- 1.62 (- 2.27, - 0.98) and - 1.31(- 1.77, - 0.86) respectively], levels of TNFα, IL-6 and IL-1β [- 2.47 (- 3.30, - 1.64), - 3.17 (- 4.74, - 1.60) and - 8.44 (- 12.4, - 4.5) respectively] and myeloperoxidase (MPO) [- 1.60 (- 2.06, - 1.14)], although with significant, primarily quantitative heterogeneity for each (I2 ≥ 53%, p < 0.01) except MPO. Treatment increased blood or tissue NAD+ levels and decreased chemical organ injury measures and oxidation markers but differently comparing species (p ≤ 0.05). Only 2 and 9 survival studies described power analyses or animal randomization respectively and no study described treatment or non-histologic outcome measure blinding. Among survival studies, Egger's analysis (p = 0.002) suggested publication bias. While suggestive, published animal studies do not yet support clinical trials testing niacin and NAD metabolite treatment for infection and sepsis. Animal studies simulating clinical conditions and with randomized, blinded designs are needed to investigate this potentially promising therapeutic approach.

Selective Impact of Selenium Compounds on Two Cytokine Storm Players

COVID-19 patients suffer from the detrimental effects of cytokine storm and not much success has been achieved to overcome this issue. We sought to test the ability of selenium to reduce the impact of two important cytokine storm players: IL-6 and TNF-α. The effects of four selenium compounds on the secretion of these cytokines from THP-1 macrophages were evaluated in vitro following an LPS challenge. Also, the potential impact of methylseleninic acid (MSeA) on Nrf2 and IκBα was determined after a short treatment of THP-1 macrophages. MSeA was found to be the most potent selenium form among the four selenium compounds tested that reduced the levels of IL-6 and TNF-α secreted by THP-1 macrophages. In addition, an increase in Nrf2 and decrease in pIκBα in human macrophages was observed following MSeA treatment. Our data indicate that COVID-19 patients might benefit from the addition of MSeA to the standard therapy due to its ability to suppress the key players in the cytokine storm.

Combination Therapy of Niacin and Apocynin Attenuates Lung Injury During Sepsis in Rats

INTRODUCTION

Oxidative stress contributes to tissue injury through reactive oxygen species-dependent signaling pathways during sepsis. We studied therapeutic benefits of the combination therapy of niacin, which increased reduced glutathione levels, and apocynin, which suppressed reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) activity, in septic rats.

MATERIALS AND METHODS

Polymicrobial sepsis was induced through cecal ligation and puncture (CLP) with antibiotics in male Sprague-Dawley rats (n = 189). The rats were randomly divided into sham, CLP, CLP + niacin, CLP + apocynin, and CLP + niacin + apocynin groups. Six hours after CLP, vehicle, niacin (360 mg/kg through the orogastric tube), and/or apocynin (20 mg/kg through intraperitoneal injection) were administered. The occurrence of mortality for 72 h after CLP was observed. Next, a separate set of animals was euthanized at 24 h post-CLP for lung tissue analyses.

RESULTS

Combination therapy with niacin and apocynin significantly improved survival in rats with sepsis (75.0% versus 28.8%, P = 0.006) but monotherapy with niacin or apocynin did not. Monotherapy with niacin and apocynin appeared to increase NADPH levels and decrease Nox levels and activity, respectively, but failed to show statistical significances. However, combination therapy significantly decreased Nox levels and activity, increased NADPH and glutathione levels, decreased intranuclear nuclear factor-κB (NF-κB) p65 levels, reduced inflammatory cytokine expression and malondialdehyde levels, and attenuated histological lung injuries.

CONCLUSIONS

Combination therapy with niacin and apocynin synergistically attenuated lung injuries and improved survival in rats with sepsis through niacin-induced glutathione redox cycle activation and apocynin-induced Nox suppression.

The role of inflammation in cadmium nephrotoxicity: NF-κB comes into view

Kidney diseases are major health problem and understanding the underlined mechanisms that lead to kidney diseases are critical research points with a marked potential impact on health. Cadmium (Cd) is a heavy metal that occurs naturally and can be found in contaminated food. Kidneys are the most susceptible organ to heavy metal intoxication as it is the main route of waste excretion. The harmful effects of Cd were previously well proved. Cd induces inflammatory responses, oxidative injury, mitochondrial dysfunction and disturbs Ca²⁺ homeostasis. The nuclear factor-kappa B (NF-κB) is a cellular transcription factor that regulates inflammation and controls the expression of many inflammatory cytokines. Therefore, great therapeutic benefits can be attained from NF-κB inhibition. In this review we focused on certain compounds including cytochalasin D, mangiferin, N-acetylcysteine, pyrrolidine dithiocarbamate, roflumilast, rosmarinic acid, sildenafil, sinapic acid, telmisartan and wogonin and certain plants as Astragalus Polysaccharide, Ginkgo Biloba and Thymus serrulatus that potently inhibit NF-κB and effectively counteracted Cd-associated renal intoxication. In conclusion, the proposed NF-κB involvement in Cd-renal intoxication clarified the underlined inflammation associated with Cd-nephropathy and the beneficial effects of NF-κB inhibitors that make them the potential to substantially optimize treatment protocols for Cd-renal intoxication.

Role of Nuclear Factor Erythroid 2 (Nrf2) in the Recovery of Long COVID-19 Using Natural Antioxidants: A Systematic Review

Coronavirus disease 2019 (COVID-19) is an infectious disease with approximately 517 million confirmed cases, with the average number of cases revealing that patients recover immediately without hospitalization. However, several other cases found that patients still experience various symptoms after 3–12 weeks, which is known as a long COVID syndrome. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can activate nuclear factor kappa beta (NF-κβ) and unbind the nuclear factor erythroid 2-related factor 2 (Nrf2) with Kelch-like ECH-associated protein 1 (Keap1), causing inhibition of Nrf2, which has an important role in antioxidant response and redox homeostasis. Disrupting the Keap1–Nrf2 pathway enhances Nrf2 activity, and has been identified as a vital approach for the prevention of oxidative stress and inflammation. Hence, natural antioxidants from various sources have been identified as a promising strategy to prevent oxidative stress, which plays a role in reducing the long COVID-19 symptoms. Oxygen-rich natural antioxidant compounds provide an effective Nrf2 activation effect that interact with the conserved amino acid residues in the Keap1-binding pocket, such as Ser602, Ser363, Ser508, and Ser555. In this review, the benefits of various natural antioxidant compounds that can modulate the Nrf2 signaling pathway, which is critical in reducing and curing long COVID-19, are highlighted and discussed.

Potential Role of Selenium in the Treatment of Cancer and Viral Infections

Selenium has been extensively evaluated clinically as a chemopreventive agent with variable results depending on the type and dose of selenium used. Selenium species are now being therapeutically evaluated as modulators of drug responses rather than as directly cytotoxic agents. In addition, recent data suggest an association between selenium base-line levels in blood and survival of patients with COVID-19. The major focus of this mini review was to summarize: the pathways of selenium metabolism; the results of selenium-based chemopreventive clinical trials; the potential for using selenium metabolites as therapeutic modulators of drug responses in cancer (clear-cell renal-cell carcinoma (ccRCC) in particular); and selenium usage alone or in combination with vaccines in the treatment of patients with COVID-19. Critical therapeutic targets and the potential role of different selenium species, doses, and schedules were discussed.

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.

Friend or Foe? The Roles of Antioxidants in Acute Lung Injury

Acute lung injury (ALI) is an acute hypoxic respiratory insufficiency caused by various intra- and extra-pulmonary injury factors. The oxidative stress caused by excessive reactive oxygen species (ROS) produced in the lungs plays an important role in the pathogenesis of ALI. ROS is a "double-edged sword", which is widely involved in signal transduction and the life process of cells at a physiological concentration. However, excessive ROS can cause mitochondrial oxidative stress, leading to the occurrence of various diseases. It is well-known that antioxidants can alleviate ALI by scavenging ROS. Nevertheless, more and more studies found that antioxidants have no significant effect on severe organ injury, and may even aggravate organ injury and reduce the survival rate of patients. Our study introduces the application of antioxidants in ALI, and explore the mechanisms of antioxidants failure in various diseases including it.

Selenium to selenoproteins - role in COVID-19

The disruption of antioxidant defense has been demonstrated in severe acute respiratory syndrome due to SARS-CoV infection. Selenium plays a major role in decreasing the ROS produced in response to various viral infections. Selenoprotein enzymes are essential in combating oxidative stress caused due to excessive generation of ROS. Selenium also has a role in inhibiting the activation of NF-κB, thus alleviating inflammation. In viral infections, selenoproteins have also been found to inhibit type I interferon responses, modulate T cell proliferation and oxidative burst in macrophages, and inhibit viral transcriptional activators. Potential virally encoded selenoproteins have been identified by computational analysis in different viral genomes like HIV-1, Japanese encephalitis virus (JEV), and hepatitis C virus. This review discusses the role and the possible mechanisms of selenium, selenoproteins, and virally encoded selenoproteins in the pathogenicity of viral infections. Identification of potential selenoproteins in the COVID 19 genome by computational tools will give insights further into their role in the pathogenesis of viral infections.

Adipose-derived mesenchymal stem cells attenuate acute lung injury and improve the gut microbiota in septic rats

BACKGROUND

We hypothesized that adipose-derived mesenchymal stem cells (ADMSCs) may ameliorate sepsis-induced acute lung injury (ALI) and change microorganism populations in the gut microbiota, such as that of Firmicutes and Bacteroidetes.

METHODS

A total of 60 male adult Sprague-Dawley (SD) rats were separated into three groups: the sham control (SC) group, the sepsis induced by cecal ligation and puncture (CLP) group, and the ADMSC treatment (CLP-ADMSCs) group, in which rats underwent the CLP procedure and then received 1 × 106 ADMSCs. Rats were sacrificed 24 h after the SC or CLP procedures. To study the role of ADMSCs during ALI caused by sepsis and examine the impact of ADMSCs on the gut microbiome composition, rat lungs were histologically evaluated using hematoxylin and eosin (H&E) staining, serum levels of pro-inflammatory factors were detected using enzyme-linked immunosorbent assay (ELISA), and fecal samples were collected and analyzed using 16S rDNA sequencing.

RESULTS

The serum levels of inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-6, were significantly increased in rats after the CLP procedure, but were significantly decreased in rats treated with ADMSCs. Histological evaluation of the rat lungs yielded results consistent with the changes in IL-6 levels among all groups. Treatment with ADMSCs significantly increased the diversity of the gut microbiota in rats with sepsis. The principal coordinates analysis (PCoA) results showed that there was a significant difference between the gut microbiota of the CLP-ADMSCs group and that of the CLP group. In rats with sepsis, the proportion of Escherichia-Shigella (P = 0.01) related to lipopolysaccharide production increased, and the proportion of Akkermansia (P = 0.02) related to the regulation of intestinal mucosal thickness and the maintenance of intestinal barrier function decreased. These changes in the gut microbiota break the energy balance, aggravate inflammatory reactions, reduce intestinal barrier functions, and promote the translocation of intestinal bacteria. Intervention with ADMSCs increased the proportion of beneficial bacteria, reduced the proportion of harmful bacteria, and normalized the gut microbiota.

CONCLUSIONS

Therapeutically administered ADMSCs ameliorate CLP-induced ALI and improves gut microbiota, which provides a potential therapeutic mechanism for ADMSCs in the treatment of sepsis.

Urinary Excretion of N1-Methylnicotinamide and N1-Methyl-2-Pyridone-5-Carboxamide and Mortality in Kidney Transplant Recipients

It is unclear whether niacin nutritional status is a target for improvement of long-term outcome after renal transplantation. The 24-h urinary excretion of N¹-methylnicotinamide (N¹-MN), as a biomarker of niacin status, has previously been shown to be negatively associated with premature mortality in kidney transplant recipients (KTR). However, recent evidence implies higher enzymatic conversion of N¹-MN to N¹-methyl-2-pyridone-5-carboxamide (2Py) in KTR, therefore the need exists for interpretation of both N¹-MN and 2Py excretion for niacin status assessment. We assessed niacin status by means of the 24-h urinary excretion of the sum of N¹-MN and 2Py (N¹-MN + 2Py), and its associations with risk of premature mortality in KTR. N¹-MN + 2Py excretion was measured in a longitudinal cohort of 660 KTR with LS-MS/MS. Prospective associations of N¹-MN + 2Py excretion were investigated with Cox regression analyses. Median N¹-MN + 2Py excretion was 198.3 (155.9–269.4) µmol/day. During follow-up of 5.4 (4.7–6.1) years, 143 KTR died, of whom 40 due to an infectious disease. N¹-MN + 2Py excretion was negatively associated with risk of all-cause mortality (HR 0.61; 95% CI 0.47–0.79; p < 0.001), and infectious mortality specifically (HR 0.47; 95% CI 0.29–0.75; p = 0.002), independent of potential confounders. Secondary analyses showed effect modification of hs-CRP on the negative prospective association of N¹-MN + 2Py excretion, and sensitivity analyses showed negative and independent associations of N¹-MN and 2Py excretion with risk of all-cause mortality separately. These findings add further evidence to niacin status as a target for nutritional strategies for improvement of long-term outcome in KTR.

Niacin and Selenium Attenuate Brain Injury After Cardiac Arrest in Rats by Up-Regulating DJ-1-Akt Signaling

OBJECTIVES

To determine neuroprotective effects and mechanism of the combination therapy of niacin and selenium in cardiac arrest rats.

DESIGN

Prospective laboratory study.

SETTING

University laboratory.

SUBJECTS

Rat cortex neurons and male Sprague-Dawley rats (n = 68).

INTERVENTIONS

In rat cortex neurons underwent 90 minutes of oxygen-glucose deprivation and 22.5 hours of reoxygenation, effects of the combination therapy of niacin (0.9 mM) and selenium (1.5 μM) were investigated. The role of DJ-1 was determined using DJ-1 knockdown cells. In cardiac arrest rats, posttreatment effects of the combination therapy of niacin (360 mg/kg) and selenium (60 μg/kg) were evaluated.

MEASUREMENTS AND MAIN RESULTS

In oxygen-glucose deprivation and 22.5 hours of reoxygenation cells, combination therapy synergistically activated the glutathione redox cycle by a niacin-induced increase in glutathione reductase and a selenium-induced increase in glutathione peroxidase activities and reduced hydrogen peroxide level. It increased phosphorylated Akt and intranuclear Nuclear factor erythroid 2-related factor 2 expression and attenuated neuronal injury. However, these benefits were negated by DJ-1 knockdown. In cardiac arrest rats, combination therapy increased DJ-1, phosphorylated Akt, and intranuclear nuclear factor erythroid 2-related factor 2 expression, suppressed caspase 3 cleavage, and attenuated histologic injury in the brain tissues. It also improved the 7-day Neurologic Deficit Scales from 71.5 (66.0-74.0) to 77.0 (74.-80.0) (p = 0.02).

CONCLUSIONS

The combination therapy of clinically relevant doses of niacin and selenium attenuated brain injury and improved neurologic outcome in cardiac arrest rats. Its benefits were associated with reactive oxygen species reduction and subsequent DJ-1-Akt signaling up-regulation.

Adipose-derived mesenchymal stem cells ameliorate the inflammatory reaction in CLP-induced septic acute lung injury rats via sTNFR1

We hypothesized that the adipose-derived mesenchymal stem cells (ADMSCs), which secrete high amounts of soluble molecules, such as soluble tumor necrosis factor receptor 1 (sTNFR1), may ameliorate sepsis-induced acute lung injury (ALI). A total of 120 male adult Sprague-Dawley rats were separated into four groups: the sham control (SC), sepsis induced by cecal ligation and puncture (CLP), CLP-ADMSCs, and CLP-sTNFR1 small interfering RNA (siRNA) groups; CLP groups underwent CLP and then received 1 × 106 ADMSCs with or without knockdown of sTNFR1 intravenously at 1 hr after surgery. Rats were killed at 3, 6, 24, and 48 hr after the SC or CLP procedures. 5-Ethynyl-2'-deoxyuridine-labeled ADMSCs extensively colonized the lungs at 6, 24, and 72 hr after injection. The lung wet/dry (W/D) weight ratios in the CLP group were higher than those in SC group; however, ADMSCs ameliorated the W/D weight ratios following CLP, and this effect was abolished by sTNFR1 siRNA treatment. The levels of serum sTNFR1 and interleukin-10 (IL-10) were higher in the CLP-ADMSCs group and lower in the SC group than in other groups; interestingly, these levels were higher in CLP and CLP-sTNFR1 siRNA groups than in SC group. Tumor necrosis factor-α and IL-6 levels increased significantly after CLP, and ADMSCs could alleviate these changes, but the effect was weakened by sTNFR1 siRNA treatment. The lung cell apoptosis and edema levels were consistent with IL-6 levels among all groups. Therapeutically administered ADMSCs secrete sTNFR1, which most likely protects against ALI in septic rats by ameliorating inflammation and lung edema.

Reuniting overnutrition and undernutrition, macronutrients, and micronutrients

Over-nutrition and its late consequences are a dominant theme in medicine today. In addition to the health hazards brought on by over-nutrition, the medical community has recently accumulated a roster of health benefits with obesity, grouped under "obesity paradox." Throughout the world and throughout history until the 20^th century, under-nutrition was a dominant evolutionary force. Under-nutrition brings with it a mix of benefits and detriments that are opposite to and continuous with those of over-nutrition. This continuum yields J-shaped or U-shaped curves relating body mass index to mortality. The overweight have an elevated risk of dying in middle age of degenerative diseases while the underweight are at increased risk of premature death from infectious conditions. Micronutrient deficiencies, major concerns of nutritional science in the 20^th century, are being neglected. This "hidden hunger" is now surprisingly prevalent in all weight groups, even among the overweight. Because micronutrient replacement is safe, inexpensive, and predictably effective, it is now an exceptionally attractive target for therapy across the spectrum of weight and age. Nutrition-related conditions worthy of special attention from caregivers include excess vitamin A, excess vitamin D, and deficiency of magnesium.

The Effect of Intravenous Selenium on Oxidative Stress in Critically Ill Patients with Acute Respiratory Distress Syndrome

OBJECTIVE

To modulate the inflammatory response in respiratory distress syndrome (ARDS) with selenium.

BACKGROUND

Selenium replenishes the glutathione peroxidase proteins that are the first line of defense for an oxidative injury to the lungs.

METHODS

Forty patients with ARDS were randomized into two groups: the SEL⁺ group being administered sodium selenite and the SEL^- group receiving normal saline for 10 days. Blood samples were taken on Day-0, DAY-7, and Day-14 for assessment of IL-1 beta, IL-6, C-reactive protein, GPx-3, and selenium. Ferric reducing antioxidant power (FRAP) was measured in the bronchial wash fluids. Pearson correlation and repeated measure analysis were performed to examine the effects of selenium on the inflammatory markers.

RESULTS

Sodium selenite replenished selenium levels in the SEL⁺ group. Selenium concentrations were linearly correlated to serum concentrations of GPx3 (R value: 0.631; P < 0.001), and FRAP (R value: -0.785; P < 0.001). Serum concentrations of both IL 1-beta (R value: -0.624; P < 0.001) and IL-6 (R value: -0.642; P < 0.001) were inversely correlated to the serum concentrations of selenium. There was a meaningful difference between two groups in airway resistance and pulmonary compliance changes (P values 0.008 and 0.028, respectively).

CONCLUSION

Selenium restored the antioxidant capacity of the lungs, moderated the inflammatory responses, and meaningfully improved the respiratory mechanics. Despite these changes, it had no effect on the overall survival, the duration of mechanical ventilation, and ICU stay. Selenium can be used safely; however, more trials are essential to examine its clinical effectiveness.

Sepsis: in search of cure

INTRODUCTION

Sepsis is a complex inflammatory disorder believed to originate from an infection by any types of microbes and/or their products. It is the leading cause of death in intensive care units (ICUs) throughout the globe. The mortality rates depend both on the severity of infection and the host's response to infection.

METHODS

Literature survey on pathobiology of sepsis in general and failure of more than hundred clinical trials conducted so far in search of a possible cure for sepsis resulted in the preparation of this manuscript.

FINDINGS

Sepsis lacks a suitable animal model that mimics human sepsis. However, based on the results obtained in animal models of sepsis, clinical trials conducted so far have been disappointing. Although involvement of multiple mediators and pathways in sepsis has been recognized, only few components are being targeted and this could be the major reason behind the failure of clinical trials.

CONCLUSION

Inability to recognize a single critical mediator of sepsis may be the underlying cause for the poor therapeutic intervention of sepsis. Therefore, sepsis is still considered as a disease-in search of cure.