Nicotinamide is a potent inhibitor of proinflammatory cytokines

Poly (ADP-Ribose) polymerase-1 (PARP-1) overactivity plays a pathogenic role in bile acids-induced nephrotoxicity in cholestatic rats

Cholestatic liver disease is a clinical complication with a wide range of etiologies. The liver is the primary organ influenced by cholestasis. Other organs, rather than the liver (e.g., kidneys), could also be affected by cholestatic liver disease. Cholestasis-induced renal injury is known as cholemic nephropathy (CN). Although the structural and functional alterations of the kidney in cholestasis have been well described, the cellular and molecular mechanisms of CN are not well understood. Some studies mentioned the role of oxidative stress and mitochondrial impairment in CN. Several cellular targets, including proteins, lipids, and DNA, could be affected by oxidative stress. Poly (ADP-Ribose) polymerase-1 (PARP-1) is an enzyme that its physiological activity plays a fundamental role in DNA repair. However, PARP-1 overexpression is associated with enhanced oxidative stress and cell death. The current study was designed to evaluate the role of PARP-1 activity in the pathogenesis of CN. Bile duct ligated (BDL) rats were treated with nicotinamide (NA) as a PARP-1 inhibitor. Kidney, urine, and plasma samples were collected at scheduled time intervals (3, 7, 14, and 28 days after BDL surgery). Serum and urine biomarkers of kidney injury, markers of oxidative stress and DNA damage, PARP-1 expression and activity in the kidney tissue, inflammatory response, renal fibrosis markers, and kidney histopathological alterations were assessed. Significant changes in the serum and urine biomarkers of kidney injury were evident in the BDL rats. Markers of oxidative stress were increased, and tissue ATP levels and antioxidant capacity were decreased in the kidney of cholestatic animals. A significant increase in PARP-1 expression and activity was evident in BDL rats (3, 7, 14, and 28 days after BDL). Moreover, inflammatory response (IL-1β and TNF-α expression; and myeloperoxidase activity), renal tissue histopathological alterations, and kidney fibrosis (α-SMA and TGF-β expression, as well as collagen deposition) were detected in cholestatic animals. It was found that the PARP-1 inhibitor, NA (50 and 100 mg/kg, i.p), significantly mitigated cholestasis-induced renal injury. The positive effects of NA were more significant at a lower dose and the early stage of CN. These data indicate a pathogenic role for PARP-1 overexpression in CN.

Role of poly (ADP) ribose polymerase-1 inhibition by nicotinamide as a possible additive treatment to modulate host immune response and prevention of cytokine storm in COVID-19

COVID-19 is rapidly spreading contagious disease spreading across the world. Patients at risk are elderly people and those with comorbidity. Early studies done on Chinese patients who suggest cytokine storm to be responsible for lung injury. We need to understand the mechanism of modulating such robust response of immunity and resultant cytokine storm. We suggest nicotinamide, a potential poly ADP ribose polymerase (PARP) inhibitor, as a supportive treatment for the prevention of cytokine storm from injuring the lung parenchyma. Nicotinamide supplementation albeit at high dose may modulate outcome in COVID-19. Nicotinamide was used previously to reduce ventilator-induced lung injury and lung injury due to hypoxia. Nicotinamide congeners are used to treat chronic lung disease like tuberculosis. Certainly, nicotinamide is effective pharmacotherapy in lung injury – whether acute or chronic. Other measures used in treating COVID-19 are focusing on targeting interleukin-6 – a cytokine responsible for mayhem, while few are targeting granulocyte-macrophage colony- stimulating factor. We suggest targeting PARP in addition to other measures to block cytokines. By inhibiting PARP course of COVID-19 may be altered. Understanding the pathophysiology of acute lung injury is crucial. PARP plays a pivotal role on cytokine release in response to any lung injury ranging from viral infection to hypoxia. Various antiviral defenses and immune response need to be studied in detail.

Blood plasma B vitamins in depression and the therapeutic response to electroconvulsive therapy

A growing body of research has indicated a role for B vitamins in depression, with some previous studies suggesting that B vitamin status in patients with depression can impact on antidepressant response. Here we aimed to investigate B vitamin plasma concentrations in medicated patients with depression (n ​= ​94) compared to age- and sex-matched healthy controls (n ​= ​57), and in patients with depression after electroconvulsive therapy (ECT) in a real-world clinical setting. Our results show that nicotinamide (vitamin B3), N1-methylnicotinamide (vitamin B3 metabolite), and pyridoxal 5'-phosphate (PLP; vitamin B6) concentrations were significantly reduced in patients with depression compared to controls. The Cohen's d effect sizes for nicotinamide, N1-methylnicotinamide, and PLP were moderate-large (-0.47, -0.51, and -0.59, respectively), and likely to be of clinical relevance. Functional biomarkers of vitamin B6 status (PAr index, 3-hydroxykynurenine: hydroxyanthranilic acid ratio, 3-hydroxykynurenine: xanthurenic acid ratio, and HKr) were elevated in depressed patients compared to controls, suggestive of reduced vitamin B6 function. Over 30% of the patient cohort were found to have low to deficient PLP concentrations, and exploratory analyses revealed that these patients had higher IL-6 and CRP concentrations compared to patients with PLP levels within the normal range. Treatment with ECT did not alter B vitamin concentrations, and B vitamin concentrations were not associated with depression severity or the therapeutic response to ECT. Overall, reduced plasma PLP, nicotinamide, and N1-methylnicotinamide concentrations could have wide ranging effects on pathways and systems implicated in depression. Further studies are required to understand the reasons why patients with depression present with low plasma B vitamin concentrations.

Muscle metabolomics analysis reveals potential biomarkers of exercise‑dependent improvement of the diaphragm function in chronic obstructive pulmonary disease

Decreased diaphragm function is a crucial factor leading to reduced ventilatory efficiency and worsening of quality of life in chronic obstructive pulmonary disease (COPD). Exercise training has been demonstrated to effectively improve the function of the diaphragm. However, the mechanism of this process has not been identified. The emergence of metabolomics has allowed the exploration of new ideas. The present study aimed to analyze the potential biomarkers of exercise-dependent enhancement of diaphragm function in COPD using metabolomics. Sprague Dawley rats were divided into three groups: COPD + exercise group (CEG); COPD model group (CMG); and control group (CG). The first two groups were exposed to cigarette smoke for 16 weeks to establish a COPD model. Then, the rats in the CEG underwent aerobic exercise training for 9 weeks. Following confirmation that exercise effectively improved the diaphragm function, a gas chromatography tandem time-of-flight mass spectrometry analysis system was used to detect the differential metabolites and associated pathways in the diaphragm muscles of the different groups. Following exercise intervention, the pulmonary function and diaphragm contractility of the CEG rats were significantly improved compared with those of the CMG rats. A total of 36 different metabolites were identified in the comparison between the CMG and the CG. Pathway enrichment analysis indicated that these different metabolites were involved in 17 pathways. A total of 29 different metabolites were identified in the comparison between the CMG and the CEG, which are involved in 14 pathways. Candidate biomarkers were selected, and the pathways analysis of these metabolites demonstrated that 2 types of metabolic pathways, the nicotinic acid and nicotinamide metabolism and arginine and proline metabolism pathways, were associated with exercise-induced pulmonary rehabilitation.

Synthesis, chemical characterization and DNA interaction study of new diclofenac and ibuprofen zinc (II)-nicotinamide ternary complexes as cyclooxygenase inhibitor prototypes

In the search for new drugs, strategies such as bioisosterism have been evidenced, in which the modification of molecules is already known to be active. Thus, metal complexes of known drugs have been highlighted, with examples of significant improvements in therapeutic efficacy. In this way, this work aimed at the synthesis of new zinc complexes with nonsteroidal anti-inflammatory drugs (NSAIDs), as well as the chemical characterization and the previous toxicity by cytotoxicity with Artemia salina, and evaluating the ability of these compounds to interact with DNA. As result, two new zinc II ternary complexes containing the NSAIDs diclofenac (Diclof) and ibuprofen (Ibup) and nicotinamide neutral linker (Nic) were obtained by the two-step solvent metal-ligand complexation method. Molecular structures were determined by NMR, FTIR, HR-MS, UV-Vis and X-ray diffraction, which demonstrated that both complexes are binuclear systems of general formula [Zn₂(R-COO^-)₄(Nic)₂]. Plasmidial DNA breakdown capacities were evaluated by producing single and double breaks (DNA FII and FIII) from plasmid incubation with complex solutions in the concentration range 0 to 400 μmol·L^-1 in experiments with the presence and absence of light. Both experiments did not show significant differences (P ≤ 0.05) in induced DNA cleavage activity between the maximum study concentrations (400 μmol·L^-1) and the negative controls for both complexes. The types of complex 1 and 2 interactions with the secondary DNA structure were determined by titrating a CT-DNA solution with complex solutions and monitored by circular dichroism spectrometry. The results showed that both complexes interact with the grooves of the secondary structure of CT-DNA by electrostatic attraction, but without evidence of alteration in the primary structure. Acute toxicity tests against Artemia salina showed that both complexes did not produce lethality >10% of the population up to a maximum concentration of 1200 μg·mL^-1 within an exposure interval of 24 h. Thus, two new compounds were synthesized, characterized and had their previous toxicities determined. These compounds are promising new drugs, with the next step being evaluations of their activity.

B Vitamins and Fatty Acids: What Do They Share with Small Vessel Disease-Related Dementia?

Many studies have been written on vitamin supplementation, fatty acid, and dementia, but results are still under debate, and no definite conclusion has yet been drawn. Nevertheless, a significant amount of lab evidence confirms that vitamins of the B group are tightly related to gene control for endothelium protection, act as antioxidants, play a co-enzymatic role in the most critical biochemical reactions inside the brain, and cooperate with many other elements, such as choline, for the synthesis of polyunsaturated phosphatidylcholine, through S-adenosyl-methionine (SAM) methyl donation. B-vitamins have anti-inflammatory properties and act in protective roles against neurodegenerative mechanisms, for example, through modulation of the glutamate currents and a reduction of the calcium currents. In addition, they also have extraordinary antioxidant properties. However, laboratory data are far from clinical practice. Many studies have tried to apply these results in everyday clinical activity, but results have been discouraging and far from a possible resolution of the associated mysteries, like those represented by Alzheimer's disease (AD) or small vessel disease dementia. Above all, two significant problems emerge from the research: No consensus exists on general diagnostic criteria-MCI or AD? Which diagnostic criteria should be applied for small vessel disease-related dementia? In addition, no general schema exists for determining a possible correct time of implementation to have effective results. Here we present an up-to-date review of the literature on such topics, shedding some light on the possible interaction of vitamins and phosphatidylcholine, and their role in brain metabolism and catabolism. Further studies should take into account all of these questions, with well-designed and world-homogeneous trials.

Does the Administration of Sevelamer or Nicotinamide Modify Uremic Toxins or Endotoxemia in Chronic Hemodialysis Patients?

BACKGROUND

Hyperphosphatemia control is a major issue in hemodialysis patients. Both sevelamer and nicotinamide are prescribed for this purpose. In addition, they exert pleiotropic effects such as an improvement of inflammatory status and potentially enhanced clearance of uremic toxins. In the present secondary analysis of the NICOREN trial, we investigated the impact of sevelamer and nicotinamide on uremic toxins, toxin precursors, and endotoxemia in chronic hemodialysis patients.

METHODS

Circulating uremic toxins (including phenylacetylglutamine, trimethylamine-N-oxide, p-cresyl sulfate, indoxyl sulfate, kynurenine, hippuric acid, indole-3-acetic acid, 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid, kynurenic acid, and p-cresyl glucuronide) and precursors were measured by ultra-performance liquid chromatography-tandem mass spectrometry, and urea, uric acid, phosphate, C-reactive protein, and intact parathyroid hormone by routine biochemistry methods. Serum endotoxin (evaluated by lipopolysaccharide levels) and C-terminal fibroblast growth factor-23 levels were measured using enzyme-linked immunosorbent assay kits.

RESULTS

One hundred hemodialysis patients were randomized to receive either nicotinamide or sevelamer treatment. Among them, 63% were male, mean (± standard deviation) age was 65 ± 14 years, 47% had diabetes mellitus, and 51% had a history of cardiovascular disease. In the sevelamer group, but not the nicotinamide group, serum levels of urea, uric acid, and fibroblast growth factor-23 were significantly reduced after 6 months of treatment. The other circulating uremic toxins and toxin precursors remained unchanged in response to either phosphate-lowering agent. Sevelamer treatment led to a marked decrease in serum lipopolysaccharide (p < 0.001) whereas nicotinamide treatment induced an only modest decrease of borderline significance (p = 0.057). There was no change in C-reactive protein levels.

CONCLUSION

In contrast to sevelamer, nicotinamide did not reduce circulating levels of low-molecular-weight uremic toxins other than phosphate, and neither agent reduced circulating uremic toxins of high-molecular-weight or protein-bound toxins. Sevelamer, but not nicotinamide, reduced serum endotoxin levels. Despite no change in serum C-reactive protein, the endotoxin-lowering effect of sevelamer may help to attenuate the inflammatory status of patients with chronic kidney disease.

The Secreted Virulence Factor NADase of Group A Streptococcus Inhibits P2X7 Receptor-Mediated Release of IL-1β

The common human pathogen Group A Streptococcus (GAS) causes superficial as well as invasive, life-threatening diseases. An increase in the occurrence of invasive GAS infection by strains of the M1 and M89 serotypes has been correlated with increased expression of the genetically and functionally linked virulence factors streptolysin O (SLO) and β-NAD⁺-glycohydrolase (NADase). NADase affects host cells differently depending on its location: its SLO-dependent translocation into the cytosol can lead to cell death through β-NAD⁺ depletion, while extracellularly located NADase inhibits IL-1β release downstream of Nlrp3 inflammasome activation. In this study, we use a macrophage infection model to investigate the NADase-dependent inhibition of IL-1β release. We show that bacteria expressing a functional NADase evade P2X7 activation, while infection with a NADase-deficient GAS strain leads to a P2X7-mediated increase in IL-1β. Further, our data indicate that in the absence of NADase, IL-1β is released through both P2X7-dependent and -independent pathways, although the precise mechanisms of how this occur are still unclear. This study adds information about the mechanism by which NADase regulates inflammasome-dependent IL-1β release, which may in part explain why increased NADase expression correlates with bacterial virulence.

NAD metabolites interfere with proliferation and functional properties of THP-1 cells

Over the past few years the NAD-related compounds nicotinamide (NAM), nicotinamide riboside (NR) and 1-methylnicotinamide (MNA) have been established as important molecules in signalling pathways that contribute to metabolic functions of many cells, including those of the immune system. Among immune cells, monocytes/macrophages, which are the major players of inflammatory processes, are especially susceptible to the anti-inflammatory action of NAM. Here we asked whether NAM and the two other compounds have the potential to regulate differentiation and LPS-induced biological answers of the monocytic cell line THP-1. We show that treatment of THP-1 cells with NAM, NR and MNA resulted in growth retardation accompanied by enrichment of cells in the G0/G1-phase independent of p21 and p53. NAM and NR caused an increase in intracellular NAD concentrations and SIRT1 and PARP1 mRNA expression was found to be enhanced. The compounds failed to up-regulate the expression of the cell surface differentiation markers CD38, CD11b and CD14. They modulated the reactive oxygen species production and primed the cells to respond less effectively to the LPS induced TNF-α production. Our data show that the NAD metabolites interfere with early events associated with differentiation of THP-1 cells along the monocytic path and that they affect LPS-induced biological responses of the cell line.

Neurocognitive Function and Quality of Life Outcomes in the ONTRAC Study for Skin Cancer Chemoprevention by Nicotinamide

Nicotinamide (vitamin B3) has photoprotective effects and reduces skin cancer incidence in high risk patients. Nicotinamide also improves cognition in animal models. As part of the ONTRAC (Oral Nicotinamide To Reduce Actinic Cancer) phase III placebo-controlled, randomized trial to assess nicotinamide’s efficacy in skin cancer prevention, we included clinical neurocognitive function and patient-reported quality of life assessments at baseline and after 12 months of intervention in individuals with previous skin cancer in order to assess any effect of oral nicotinamide (500 mg po twice daily) on cognitive function and quality of life. In our sample of 310 participants who completed neurocognitive function testing at baseline and at 12 months, we were not able to detect any significant effect of oral nicotinamide on cognitive function nor on quality of life. Further studies of nicotinamide’s effects on cognition in humans might include individuals with pre-existing mild cognitive impairment, and it may be that higher doses of nicotinamide are required to significantly influence cognitive function compared to doses required to reduce skin cancer.

Effects of nicotinamide on spatial memory and inflammation after juvenile traumatic brain injury

Age is a consistent predictor of outcome following traumatic brain injury (TBI). Although children and adolescents have the highest rate of hospitalizations and long-term disabilities, few preclinical studies have attempted to model and treat TBI in this population. Studies using nicotinamide (NAM), a soluble B-group vitamin, in older animals (3-6 months) have shown improved functional recovery in experimental models of TBI. The purpose of this study was two-fold: to examine the preclinical efficacy of NAM at different doses on behavioral outcomes in juvenile rats and examine the microglial response over time. Groups of juvenile rats (PND 28-60) were assigned to sham, NAM (125 mg/kg, 500 mg/kg, or 1000 mg/kg) or saline (1 mL/kg) and received unilateral cortical contusion injuries (CCI) and received injections at 15 min, 24 h, and 72 h after injury. Animals treated with NAM demonstrated no significant behavioral improvements over saline treatments. NAM treatments did however show slowed cortical loss and reduced microglia compared to saline treated animals. In summary, the preclinical efficacy of NAM as a treatment following CCI in juvenile animals differs from that previously documented in older rat models. While NAM treatments did reduce microglial activity and slowed progression of cortical loss, it did not reduce the total cortical volume lost nor did it improve behavioral outcomes. The findings of this study emphasize the need to examine potential treatments for TBI utilizing juvenile populations and may explain why so many treatments have failed in clinical trials.

Multi-targeted Effect of Nicotinamide Mononucleotide on Brain Bioenergetic Metabolism

Dysfunctions in NAD⁺ metabolism are associated with neurodegenerative diseases, acute brain injury, diabetes, and aging. Loss of NAD⁺ levels results in impairment of mitochondria function, which leads to failure of essential metabolic processes. Strategies to replenish depleted NAD⁺ pools can offer significant improvements of pathologic states. NAD⁺ levels are maintained by two opposing enzymatic reactions, one is the consumption of NAD⁺ while the other is the re-synthesis of NAD⁺. Inhibition of NAD⁺ degrading enzymes, poly-ADP-ribose polymerase 1 (PARP1) and ectoenzyme CD38, following brain ischemic insult can provide neuroprotection. Preservation of NAD⁺ pools by administration of NAD⁺ precursors, such as nicotinamide (Nam) or nicotinamide mononucleotide (NMN), also offers neuroprotection. However, NMN treatment demonstrates to be a promising candidate as a therapeutic approach due to its multi-targeted effect acting as PARP1 and CD38 inhibitor, sirtuins activator, mitochondrial fission inhibitor, and NAD⁺ supplement. Many neurodegenerative diseases or acute brain injury activate several cellular death pathways requiring a treatment strategy that will target these mechanisms. Since NMN demonstrated the ability to exert its effect on several cellular metabolic pathways involved in brain pathophysiology it seems to be one of the most promising candidates to be used for successful neuroprotection.

Increased Mortality in Mice following Immunoprophylaxis Therapy with High Dosage of Nicotinamide in Burkholderia Persistent Infections

Bacterial persistence, known as noninherited antibacterial resistance, is a factor contributing to the establishment of long-lasting chronic bacterial infections. In this study, we examined the ability of nicotinamide (NA) to potentiate the activity of different classes of antibiotics against Burkholderia thailandensis persister cells.

Bacterial persistence, known as noninherited antibacterial resistance, is a factor contributing to the establishment of long-lasting chronic bacterial infections. In this study, we examined the ability of nicotinamide (NA) to potentiate the activity of different classes of antibiotics against Burkholderia thailandensis persister cells. Here we demonstrate that addition of NA in in vitro models of B. thailandensis infection resulted in a significant depletion of the persister population in response to various classes of antibiotics. We applied microfluidic bioreactors with a continuous medium flow to study the effect of supplementation with an NA gradient on the recovery of B. thailandensis persister populations. A coculture of human neutrophils preactivated with 50 µM NA and B. thailandensis resulted in the most efficient reduction in the persister population. Applying single-cell RNA fluorescence in situ hybridization analysis and quantitative PCR, we found that NA inhibited gene expression of the stringent response regulator relA, implicated in the regulation of the persister metabolic state. We also demonstrate that a therapeutic dose of NA (250 mg/kg of body weight), previously applied as immunoprophylaxis against antibiotic-resistant bacterial species, produced adverse effects in an in vivo murine model of infection with the highly pathogenic bacterium Burkholderia pseudomallei, indicating that therapeutic dose and metabolite effects have to be carefully evaluated and tailored for every case of potential clinical application.

Autophagy: A new concept in autoimmunity regulation and a novel therapeutic option

Nowadays, pharmacologic treatments of autoinflammatory diseases are largely palliative rather than curative. Most of them result in non-specific immunosuppression, which can be associated with broad disruption of natural and induced immunity with significant and sometimes serious unwanted injuries. Among the novel strategies that are under development, tools that modulate the immune system to restore normal tolerance mechanisms are central. In these approaches, peptide therapeutics constitute a class of agents that display many physicochemical advantages. Within this class of potent drugs, the phosphopeptide P140 is very promising for treating patients with lupus, and likely also patients with other chronic inflammatory diseases. We discovered that P140 targets autophagy, a finely orchestrated catabolic process, involved in the regulation of inflammation and in the biology of immune cells. In vitro, P140 acts directly on a particular form of autophagy called chaperone-mediated autophagy, which seems to be hyperactivated in certain subsets of lymphocytes in lupus and in other autoinflammatory settings. In lupus, the "correcting" effect of P140 on autophagy results in a weaker signaling of autoreactive T cells, leading to a significant improvement of pathophysiological status of treated mice. These findings also demonstrated ex vivo in human cells, open novel avenues of therapeutic intervention in pathological conditions, in which specific and not general targeting is highly pursued in the context of the new action plans for personalized medicines.

Tacrolimus nanoparticles based on chitosan combined with nicotinamide: enhancing percutaneous delivery and treatment efficacy for atopic dermatitis and reducing dose

Background

Topical application of tacrolimus (FK506) was effective in the treatment of atopic dermatitis (AD); however, adverse effects frequently occurred with the increase of FK506 dose during long–term treatment.

Objective

The objective of this project was to develop a hybrid skin targeting system encapsulating FK506 based on nicotinamide (NIC) and chitosan nanoparticles (CS–NPs), ie, FK506–NIC–CS–NPs, which took advantages of both of NIC and CS–NPs to obtain the synergetic effects of percutaneous delivery and treatment efficacy enhancement along with dose reduction.

Methods

The formulation of FK506–NIC–CS–NPs was optimized and characterized. In vitro and in vivo skin permeation studies were performed. AD–like skin lesions were constructed with BALB/c mice by 1–chloro–2, 4–dinitrobenzene (DNCB)–induced, and FK506–NIC–CS–NPs containing different dose of FK506 were topically administered to treat AD–like skin lesions in comparison with Protopic.

Results

NIC was found to significantly increase the FK506 EE to 92.2% by CS–NPs. In comparison with commercial FK506 ointment (Protopic), in vitro and in vivo skin permeation studies demonstrated that NIC–CS–NPs system significantly enhanced FK506 permeation through and into the skin, and deposited more FK506 into the skin. The treatment efficacy on clinical symptoms, histological analysis, and molecular biology of the AD–mice demonstrated that NIC–CS–NPs with ~1/3 dose of FK506 of Protopic was superior to that of Protopic, and NIC–CS–NPs vehicle exhibited the adjuvant therapy and moderate anti–AD effects.

Conclusion

The system of NIC–CS–NPs enhances the permeability of FK506, plays an adjuvant role in anti-AD, reduces the dose of FK506 in treating AD, and is therefore a promising nanoscale system of FK506 for the effective treatment of AD.

Inhibition of Inflammasome-Dependent Interleukin 1β Production by Streptococcal NAD+-Glycohydrolase: Evidence for Extracellular Activity

Group A Streptococcus (GAS) is a common human pathogen and the etiologic agent of a large number of diseases ranging from mild, self-limiting infections to invasive life-threatening conditions. Two prominent virulence factors of this bacterium are the genetically and functionally linked pore-forming toxin streptolysin O (SLO) and its cotoxin NAD⁺-glycohydrolase (NADase). Overexpression of these toxins has been linked to increased bacterial virulence and is correlated with invasive GAS disease. NADase can be translocated into host cells by a SLO-dependent mechanism, and cytosolic NADase has been assigned multiple properties such as protection of intracellularly located GAS bacteria and induction of host cell death through energy depletion. Here, we used a set of isogenic GAS mutants and a macrophage infection model and report that streptococcal NADase inhibits the innate immune response by decreasing inflammasome-dependent interleukin 1β (IL-1β) release from infected macrophages. Regulation of IL-1β was independent of phagocytosis and ensued also under conditions not allowing SLO-dependent translocation of NADase into the host cell cytosol. Thus, our data indicate that NADase not only acts intracellularly but also has an immune regulatory function in the extracellular niche.

In the mid-1980s, the incidence and severity of invasive infections caused by serotype M1 GAS suddenly increased. The results of genomic analyses suggested that this increase was due to the spread of clonal bacterial strains and identified a recombination event leading to enhanced production of the SLO and NADase toxins in these strains. However, despite its apparent importance in GAS pathogenesis, the function of NADase remains poorly understood. In this study, we demonstrate that NADase inhibits inflammasome-dependent IL-1β release from infected macrophages. While previously described functions of NADase pertain to its role upon SLO-mediated translocation into the host cell cytosol, our data suggest that the immune regulatory function of NADase is exerted by nontranslocated enzyme, identifying a previously unrecognized extracellular niche for NADase functionality. This immune regulatory property of extracellular NADase adds another possible explanation to how increased secretion of NADase correlates with bacterial virulence.

Effects of nanoparticles with hydrotropic nicotinamide on tacrolimus: permeability through psoriatic skin and antipsoriatic and antiproliferative activities

The hybrid system based on nanoparticles (NPs) self-assembled by the conjugations of hyaluronic acid with cholesterol (HA–Chol NPs) combined with nicotinamide (NIC) for tacrolimus (FK506), ie, FK506 NPs–NIC, has been confirmed to exhibit a significant synergistic effect on FK506 permeation through and into intact skin; thus, it may be a promising approach for FK506 to effectively treat skin diseases. The aim of this study was to evaluate its potential for the treatment of psoriasis. In vitro permeation through the psoriatic skin was carried out, and the results revealed that the combination of NPs with NIC exhibited a significant synergistic effect on FK506 deposition within the psoriatic skin (3.40±0.67 μg/cm²) and penetration through the psoriatic skin (30.86±9.66 μg/cm²). The antipsoriatic activity of FK506 NPs–NIC was evaluated through the treatment for imiquimod (IMQ)-induced psoriasis. The psoriasis area and severity index (PASI) score demonstrated that FK506 HA–Chol NPs–NIC exerted the effect on ameliorating the skin lesions comparable to clobetasol propionate (a positive drug for psoriasis) and superior to commercial FK506 ointment (Protopic^®), and the histological study showed that it presented a synergistic effect on antipsoriasis after FK506 incorporation into NPs combined with NIC hydrotropic system, which might ultimately increase the therapeutic effect and minimize the systemic side effects by reducing the overall dose of FK506. RAW 264.7 cell uptake presented the enhancement of drugs delivered into cells by HA–Chol NPs–NIC. The antiproliferative activity on HaCaT cells identified that FK506 HA–Chol NPs–NIC exhibited significant inhibiting effects on HaCaT proliferation. The results support that the combination of HA–Chol NPs with NIC is a promising approach for FK506 for the treatment of psoriasis.

The biodistribution of 5-[18F]fluoropyrazinamide in Mycobacterium tuberculosis-infected mice determined by positron emission tomography

5-[¹⁸F]F-pyrazinamide (5-[¹⁸F]F-PZA), a radiotracer analog of the first-line tuberculosis drug pyrazinamide (PZA), was employed to determine the biodistribution of PZA using PET imaging and ex vivo analysis. 5-[¹⁸F]F-PZA was synthesized in 60 min using a halide exchange reaction. The overall decay-corrected yield of the reaction was 25% and average specific activity was 2.6 × 10⁶ kBq (70 mCi)/μmol. The biodistribution of 5-[¹⁸F]F-PZA was examined in a pulmonary Mycobacterium tuberculosis mouse model, where rapid distribution of the tracer to the lung, heart, liver, kidney, muscle, and brain was observed. The concentration of 5-[¹⁸F]F-PZA was not significantly different between infected and uninfected lung tissue. Biochemical and microbiological studies revealed substantial differences between 5-F-PZA and PZA. 5-F-PZA was not a substrate for pyrazinamidase, the bacterial enzyme that activates PZA, and the minimum inhibitory concentration for 5-F-PZA against M. tuberculosis was more than 100-fold higher than that for PZA.

Nicotinamide mononucleotide inhibits post-ischemic NAD(+) degradation and dramatically ameliorates brain damage following global cerebral ischemia

Nicotinamide adenine dinucleotide (NAD(+)) is an essential cofactor for multiple cellular metabolic reactions and has a central role in energy production. Brain ischemia depletes NAD(+) pools leading to bioenergetics failure and cell death. Nicotinamide mononucleotide (NMN) is utilized by the NAD(+) salvage pathway enzyme, nicotinamide adenylyltransferase (Nmnat) to generate NAD(+). Therefore, we examined whether NMN could protect against ischemic brain damage. Mice were subjected to transient forebrain ischemia and treated with NMN or vehicle at the start of reperfusion or 30min after the ischemic insult. At 2, 4, and 24h of recovery, the proteins poly-ADP-ribosylation (PAR), hippocampal NAD(+) levels, and expression levels of NAD(+) salvage pathway enzymes were determined. Furthermore, animal's neurologic outcome and hippocampal CA1 neuronal death was assessed after six days of reperfusion. NMN (62.5mg/kg) dramatically ameliorated the hippocampal CA1 injury and significantly improved the neurological outcome. Additionally, the post-ischemic NMN treatment prevented the increase in PAR formation and NAD(+) catabolism. Since the NMN administration did not affect animal's temperature, blood gases or regional cerebral blood flow during recovery, the protective effect was not a result of altered reperfusion conditions. These data suggest that administration of NMN at a proper dosage has a strong protective effect against ischemic brain injury.

Effect of C-peptide Alone or in Combination with Nicotinamide on Insulin Levels from Pancreatic Islets in Mouse

BACKGROUND

Both c-peptide and nicotinamide are known to increase blood insulin in diabetes. In the present study, we examined the effect of c-peptide alone or in combination with nicotinamide on insulin levels in pancreatic islets in mice.

METHODS

This study was conducted with 60 adult male Naval Medical Research Institute (NMARI) mice weighing 25 to 30 g. Pancreatic islets from normal mice were isolated by the collagenase digestion method. Mice were divided into ten groups of six (n = 6): control, glyburide (1 and 10 μM), C-peptide (50 and 100 nM), nicotinamide (10, 25, and 100 mM), nicotinamide + C-peptide (100 mM and 100 nM), and buffer in different glucose concentrations (2.8, 5.6, and 16.7 mM). Insulin secretion was measured using insulin radioimmunoassay method.

RESULTS

Insulin secretion significantly increased at 16.7 mM glucose concentration compared with 2.8 and 5.6 mM glucose concentrations. Incubation of islets at 2.8 and 5.6 mM glucose concentrations and nicotinamide + C-peptide, nicotinamide 25 and 100 mM, and C-peptide 100 nM significantly increased insulin secretion compared with the control group. In addition, incubation of islets at 16.7 mM glucose with nicotinamide + C-peptide significantly increased insulin secretion. Glyburide at 10 μM concentration was more effective than nicotinamide at 10 and 100 mM, C-peptide 50 and 100 nM in the presence of 16.7 mM glucose concentration. However, the combination of nicotinamide + C-peptide was more effective than glyburide at a concentration of 10 μM in the presence of a 16.7 mM glucose concentration.

CONCLUSIONS

This paper suggests that c-peptide, nicotinamide, and the combination of c-peptide and nicotinamide in-creases insulin secretion from pancreatic islets.

Nicotinamide: a vitamin able to shift macrophage differentiation toward macrophages with restricted inflammatory features

The differentiation of human monocytes into macrophages is influenced by environmental signals. Here we asked in how far nicotinamide (NAM), a vitamin B3 derivative known to play a major role in nicotinamide adenine dinucleotide (NAD)-mediated signaling events, is able to modulate monocyte differentiation into macrophages developed in the presence of granulocyte macrophage colony-stimulating factor (GM-MØ) or macrophage colony-stimulating factor (M-MØ). We found that GM-MØ undergo biochemical, morphological and functional modifications in response to NAM, whereas M-MØ were hardly affected. GM-MØ exposed to NAM acquired an M-MØ-like structure while the LPS-induced production of pro-inflammatory cytokines and COX-derived eicosanoids were down-regulated. In contrast, NAM had no effect on the production of IL-10 or the cytochrome P450-derived eicosanoids. Administration of NAM enhanced intracellular NAD concentrations; however, it did not prevent the LPS-mediated drain on NAD pools. In search of intracellular molecular targets of NAM known to be involved in LPS-induced cytokine and eicosanoid synthesis, we found NF-κB activity to be diminished. In conclusion, our data show that vitamin B3, when present during the differentiation of monocytes into GM-MØ, interferes with biochemical pathways resulting in strongly reduced pro-inflammatory features.

Nicotinamide exacerbates hypoxemia in ventilator-induced lung injury independent of neutrophil infiltration

Background

Ventilator-induced lung injury is a form of acute lung injury that develops in critically ill patients on mechanical ventilation and has a high degree of mortality. Nicotinamide phosphoribosyltransferase is an enzyme that is highly upregulated in ventilator-induced lung injury and exacerbates the injury when given exogenously. Nicotinamide (vitamin B3) directly inhibits downstream pathways activated by Nicotinamide phosphoribosyltransferase and is protective in other models of acute lung injury.

Methods

We administered nicotinamide i.p. to mice undergoing mechanical ventilation with high tidal volumes to study the effects of nicotinamide on ventilator-induced lung injury. Measures of injury included oxygen saturations and bronchoalveolar lavage neutrophil counts, protein, and cytokine levels. We also measured expression of nicotinamide phosophoribosyltransferase, and its downstream effectors Sirt1 and Cebpa, Cebpb, Cebpe. We assessed the effect of nicotinamide on the production of nitric oxide during ventilator-induced lung injury. We also studied the effects of ventilator-induced lung injury in mice deficient in C/EBPε.

Results

Nicotinamide treatment significantly inhibited neutrophil infiltration into the lungs during ventilator-induced lung injury, but did not affect protein leakage or cytokine production. Surprisingly, mice treated with nicotinamide developed significantly worse hypoxemia during mechanical ventilation. This effect was not linked to increases in nitric oxide production or alterations in expression of Nicotinamide phosphoribosyl transferase, Sirt1, or Cebpa and Cebpb. Cebpe mRNA levels were decreased with either nicotinamide treatment or mechanical ventilation, but mice lacking C/EBPε developed the same degree of hypoxemia and ventilator-induced lung injury as wild-type mice.

Conclusions

Nicotinamide treatment during VILI inhibits neutrophil infiltration of the lungs consistent with a strong anti-inflammatory effect, but paradoxically also leads to the development of significant hypoxemia. These findings suggest that pulmonary neutrophilia is not linked to hypoxemia in ventilator-induced lung injury, and that nicotinamide exacerbates hypoxemia during VILI.

The biochemical pathways of central nervous system neural degeneration in niacin deficiency

Neural degeneration is a very complicated process. In spite of all the advancements in the molecular chemistry, there are many unknown aspects of the phenomena of neurodegeneration which need to be put together. It is a common sequela of the conditions of niacin deficiency. Neural degeneration in Pellagra manifests as chromatolysis mainly in pyramidal followed by other neurons and glial cells. However, there is a gross lack of understanding of biochemical mechanisms of neurodegeneration in niacin deficiency states. Because of the necessity of niacin or its amide derivative NAD in a number of biochemical pathways, it is understandable that several of these pathways may be involved in the common outcome of neural degeneration. Here, we highlight five pathways that could be involved in the neuraldegeneration for which evidence has accumulated through several studies. These pathways are: 1) the tryptophan-kyneurenic acid pathway, 2) the mitochondrial ATP generation related pathways, 3) the poly (ADP-ibose) polymerase (PARP) pathway, 4) the BDNF-TRKB Axis abnormalities, 5) the genetic influences of niacin deficiency.

Inputs and outputs of poly(ADP-ribosyl)ation: Relevance to oxidative stress

Oxidative stress can cause DNA breaks which induce activation of the DNA nick sensor enzyme poly(ADP-ribose) polymerase-1 (PARP-1), part of the 17 member PARP enzyme family. PARP-1 modifies target proteins by attaching to them several NAD-derived ADP-ribose units forming poly(ADP-ribose) (PAR) polymers. PARylation controls many cellular processes while intense PARylation may also lead to cell death by various mechanisms. Here we summarize the modes of activation, inhibitors and modulators of PARP-1 and review the cellular functions regulated by the enzyme.

Skin health in older age

As people age, their skin undergoes changes which result in reduced elasticity, increased fragility and an altered immune response; in essence it becomes frail. As life expectancy is increasing the health of older skin is becoming a progressively more important facet of overall care. In addition to the consequences of ageing for otherwise healthy skin, the relative incidence of some dermatological conditions is age-dependent. In particular, xerosis (dry skin), cutaneous malignancies and skin injuries are more common in older people. In this review we describe the functional consequences of skin ageing and discuss the current evidence on how skin health may be maintained and dermatological conditions prevented in an ageing population. The future of dermatological health-care provision in the older population relies on the development of coordinated pathways of care, which start from a young age. Better quality research coordinated by the establishment of institutions dealing with skin health and ageing would be a method of addressing these needs.

Niacinamide - mechanisms of action and its topical use in dermatology

Niacinamide, an amide of vitamin B3 (niacin), is a hydrophilic endogenous substance. Its effects after epicutaneous application have long been described in the literature. Given a sufficient bioavailability, niacinamide has antipruritic, antimicrobial, vasoactive, photo-protective, sebostatic and lightening effects depending on its concentration. Within a complex metabolic system niacinamide controls the NFκB-mediated transcription of signalling molecules by inhibiting the nuclear poly (ADP-ribose) polymerase-1 (PARP-1). Niacinamide is a well-tolerated and safe substance often used in cosmetics. Clinical data for its therapeutic use in various dermatoses can increasingly be found in the literature. Although the existing data are not sufficient for a scientifically founded evaluation, it can be stated that the use of niacinamide in galenic preparations for epicutaneous application offers most interesting prospects.

Niacin activates the G protein estrogen receptor (GPER)-mediated signalling

Nicotinic acid, also known as niacin, is the water soluble vitamin B3 used for decades for the treatment of dyslipidemic diseases. Its action is mainly mediated by the G protein-coupled receptor (GPR) 109A; however, certain regulatory effects on lipid levels occur in a GPR109A-independent manner. The amide form of nicotinic acid, named nicotinamide, acts as a vitamin although neither activates the GPR109A nor exhibits the pharmacological properties of nicotinic acid. In the present study, we demonstrate for the first time that nicotinic acid and nicotinamide bind to and activate the GPER-mediated signalling in breast cancer cells and cancer-associated fibroblasts (CAFs). In particular, we show that both molecules are able to promote the up-regulation of well established GPER target genes through the EGFR/ERK transduction pathway. As a biological counterpart, nicotinic acid and nicotinamide induce proliferative and migratory effects in breast cancer cells and CAFs in a GPER-dependent fashion. Moreover, nicotinic acid prevents the up-regulation of ICAM-1 triggered by the pro-inflammatory cytokine TNF-α and stimulates the formation of endothelial tubes through GPER in HUVECs. Together, our findings concerning the agonist activity for GPER displayed by both nicotinic acid and nicotinamide broaden the mechanisms involved in the biological action of these molecules and further support the potential of a ligand to induce different responses mediated in a promiscuous manner by distinct GPCRs.

Nicotinamide and the skin

Nicotinamide, an amide form of vitamin B3, boosts cellular energy and regulates poly-ADP-ribose-polymerase 1, an enzyme with important roles in DNA repair and the expression of inflammatory cytokines. Nicotinamide shows promise for the treatment of a wide range of dermatological conditions, including autoimmune blistering disorders, acne, rosacea, ageing skin and atopic dermatitis. In particular, recent studies have also shown it to be a potential agent for reducing actinic keratoses and preventing skin cancers.

Potential roles of HDAC inhibitors in mitigating ischemia-induced brain damage and facilitating endogenous regeneration and recovery

Ischemic stroke is a leading cause of death and disability worldwide, with few available treatment options. The pathophysiology of cerebral ischemia involves both early phase tissue damage, characterized by neuronal death, inflammation, and blood-brain barrier breakdown, followed by late phase neurovascular recovery. It is becoming clear that any promising treatment strategy must target multiple points in the evolution of ischemic injury to provide substantial therapeutic benefit. Histone deacetylase (HDAC) inhibitors are a class of drugs that increase the acetylation of histone and non-histone proteins to activate transcription, enhance gene expression, and modify the function of target proteins. Acetylation homeostasis is often disrupted in neurological conditions, and accumulating evidence suggests that HDAC inhibitors have robust protective properties in many preclinical models of these disorders, including ischemic stroke. Specifically, HDAC inhibitors such as trichostatin A, valproic acid, sodium butyrate, sodium 4-phenylbutyrate, and suberoylanilide hydroxamic acid have been shown to provide robust protection against excitotoxicity, oxidative stress, ER stress, apoptosis, inflammation, and bloodbrain barrier breakdown. Concurrently, these agents can also promote angiogenesis, neurogenesis and stem cell migration to dramatically reduce infarct volume and improve functional recovery after experimental cerebral ischemia. In the following review, we discuss the mechanisms by which HDAC inhibitors exert these protective effects and provide evidence for their strong potential to ultimately improve stroke outcome in patients.

The Arabidopsis class II sirtuin is a lysine deacetylase and interacts with mitochondrial energy metabolism

The posttranslational regulation of proteins by lysine (Lys) acetylation has recently emerged to occur not only on histones, but also on organellar proteins in plants and animals. In particular, the catalytic activities of metabolic enzymes have been shown to be regulated by Lys acetylation. The Arabidopsis (Arabidopsis thaliana) genome encodes two predicted sirtuin-type Lys deacetylases, of which only Silent Information Regulator2 homolog (SRT2) contains a predicted presequence for mitochondrial targeting. Here, we have investigated the function of SRT2 in Arabidopsis. We demonstrate that SRT2 functions as a Lys deacetylase in vitro and in vivo. We show that SRT2 resides predominantly at the inner mitochondrial membrane and interacts with a small number of protein complexes mainly involved in energy metabolism and metabolite transport. Several of these protein complexes, such as the ATP synthase and the ATP/ADP carriers, show an increase in Lys acetylation in srt2 loss-of-function mutants. The srt2 plants display no growth phenotype but rather a metabolic phenotype with altered levels in sugars, amino acids, and ADP contents. Furthermore, coupling of respiration to ATP synthesis is decreased in these lines, while the ADP uptake into mitochondria is significantly increased. Our results indicate that SRT2 is important in fine-tuning mitochondrial energy metabolism.

Nicotinamide treatment reduces the levels of oxidative stress, apoptosis, and PARP-1 activity in Aβ(1-42)-induced rat model of Alzheimer's disease

The underlying mechanisms of Alzheimer's Disease (AD) are still unclear. It is suggested that poly(ADP-ribose) polymerase-1 (PARP-1) overactivation can cause neuroinflammation and cell death. In this study we searched the effects of nicotinamide (NA), endogenous PARP-1 inhibitor, on oxidative stress, apoptosis, and the regulation of PARP-1 and nuclear factor kappa B (NF-κB) in amyloid beta peptide (1-42) (Aβ(1-42))-induced neurodegeneration. Sprague-Dawley rats were divided into four groups as control, Aβ(1-42), Aβ(1-42) + NA(100 and 500 mg/kg). All groups were stereotaxically injected bilaterally into the hippocampus with Aβ(1-42) or saline. After surgery NA administrations were made intraperitoneally (ip) for 7 days. In order to investigate the effects of Aβ(1-42) and NA, protein carbonyls, lipid peroxidation, reactive oxygen species (ROS) production, glutathione (GSH) levels, activities of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), mitochondrial function, mRNA and protein levels of PARP-1, NF-κB, p53, Bax, and Bcl-2 were measured in specific brain regions such as cortex and hippocampus. Aβ(1-42) treatment only increased the oxidative stress parameters and caused decline in antioxidant enzyme activities, mitochondrial function, and GSH levels. Also, overexpression of PARP-1, NF-κB, p53, Bax, and the decreased levels of Bcl-2 were observed in Aβ(1-42)-treated group. NA treatments against Aβ(1-42)-upregulated Bcl-2 and downregulated PARP-1, NF-κB, p53, and Bax levels. NA treatments also decreased the oxidative stress parameters and elevated antioxidant enzyme activities, GSH levels, and mitochondrial function against Aβ(1-42) treatment. These data suggest that NA may have a therapeutic potential in neurodegenerative processes due to the decreased levels of oxidative stress, apoptosis, and PARP-1 activity.

Host targeted activity of pyrazinamide in Mycobacterium tuberculosis infection

Pyrazinamide (PZA) is one of the first line antibiotics used for the treatment of tuberculosis (TB). In the present study, we have used in vitro and in vivo systems to investigate whether PZA, in addition to its known anti-mycobacterial properties, modulate the host immune response during Mycobacterium tuberculosis (Mtb) infection. In vitro we have examined the effect of PZA on cytokine and chemokine release by Mtb-infected or Toll-like receptor (TLR) -stimulated primary human monocytes. In vivo, we have investigated at the transcriptional levels using genome-wide microarray gene expression analysis, whether PZA treatment of Mtb-infected mice alters the host immune response to Mtb infection in the lungs. Here, we report that PZA treatment of Mtb-infected human monocytes and mice significantly reduces the release of pro-inflammatory cytokines and chemokines, including IL-1β, IL-6, TNF-α and MCP-1 at the protein and at the gene transcription levels, respectively. Data from microarray analysis also reveal that PZA treatment of Mtb-infected mice significantly alters the expression level of genes involved in the regulation of the pro-inflammatory mediators, lung inflammatory response and TLR signaling networks. Specifically, genes coding for adenylate cyclase and Peroxisome-Proliferator Activated Receptor (PPAR), molecules known for their anti-inflammatory effect, were found to be up-regulated in the lungs of PZA-treated Mtb-infected mice. Based on the microarray findings, we propose that PZA treatment modulates the host immune response to Mtb infection by reducing pro-inflammatory cytokine production, probably through PPAR- and NF-kB- dependent pathways. In addition, our results suggest that inclusion or exclusion of PZA in the TB treatment regimen could potentially affect the biomarker signature detected in the circulation of TB patients.

Mitochondrial dysfunction and NAD(+) metabolism alterations in the pathophysiology of acute brain injury

Mitochondrial dysfunction is commonly believed to be one of the major players in mechanisms of brain injury. For several decades, pathologic mitochondrial calcium overload and associated opening of the mitochondrial permeability transition (MPT) pore were considered a detrimental factor causing mitochondrial damage and bioenergetics failure. Mitochondrial and cellular bioenergetic metabolism depends on the enzymatic reactions that require NAD(+) or its reduced form NADH as cofactors. Recently, it was shown that NAD(+) also has an important function as a substrate for several NAD(+) glycohydrolases whose overactivation can contribute to cell death mechanisms. Furthermore, downstream metabolites of NAD(+) catabolism can also adversely affect cell viability. In contrast to the negative effects of NAD(+)-catabolizing enzymes, enzymes that constitute the NAD(+) biosynthesis pathway possess neuroprotective properties. In the first part of this review, we discuss the role of MPT in acute brain injury and its role in mitochondrial NAD(+) metabolism. Next, we focus on individual NAD(+) glycohydrolases, both cytosolic and mitochondrial, and their role in NAD(+) catabolism and brain damage. Finally, we discuss the potential effects of downstream products of NAD(+) degradation and associated enzymes as well as the role of NAD(+) resynthesis enzymes as potential therapeutic targets.

Nicotinamide downregulates gene expression of interleukin-6, interleukin-10, monocyte chemoattractant protein-1, and tumour necrosis factor-α gene expression in HaCaT keratinocytes after ultraviolet B irradiation

Ultraviolet (UV) radiation has profound effects on human skin, causing sunburn, inflammation, cellular-tissue injury, cell death, and skin cancer. Most of these effects are mediated by a number of cytokines produced by keratinocytes. In this study we investigated whether nicotinamide (NCT), the amide form of vitamin B3, might have a protective function in reducing the expression of interleukin (IL)-1β, IL-6, IL-8, IL-10, monocyte chemoattractant protein (MCP)-1 and tumour necrosis factor (TNF)-α in UV-irradiated keratinocytes. HaCaT cells were treated with UVB in the presence or absence of NCT, and cytokine mRNA levels were examined by quantitative real-time PCR. NCT significantly downregulated IL-6, IL-10, MCP-1 and TNF-α mRNA expression, whereas it did not exert any significant effect on IL-1β or IL-8 expression. Because of its ability to decrease these cytokine mediators after UV exposure, NCT is a possible therapy to improve or prevent conditions induced or aggravated by UV light.

Inhibition of pre-B cell colony-enhancing factor (PBEF/NAMPT/visfatin) decreases the ability of human neutrophils to generate reactive oxidants but does not impair bacterial killing

NAMPT, also known as PBEF and visfatin, can act extracellularly as a cytokine-like molecule or intracellularly as a NAMPT, regulating NAD biosynthesis in the NAD salvage pathway. Inhibitors of NAMPT have anti-inflammatory and anticancer activity and are finding use as therapeutic agents. In view of the importance of NAD metabolism in neutrophil function, we determined the effects of NAMPT inhibition on a variety of neutrophil functions associated with their role in host protection against infections. Incubation of human neutrophils with the NAMPT inhibitor APO866 decreased neutrophil NAD(P)/H levels in a dose- and time-dependent manner but without a concomitant change in cell viability. NAMPT inhibition did not affect the expression of a number of cell-surface receptors involved in adhesion and opsono-phagocytosis, but the respiratory burst was decreased significantly. Whereas opsono-phagocytosis of Staphylococcus aureus was unaffected by NAMPT inhibition, intraphagosomal oxidant production was decreased. However, the killing efficiency of neutrophils was unaffected. These data indicate that therapeutic NAMPT inhibition is unlikely to have deleterious effects on host protection against infections, in spite of this ability to down-regulate neutrophil respiratory burst activity significantly.

The effects of human umbilical cord perivascular cells on rat hepatocyte structure and functional polarity

Hepatocyte culture is a useful tool for the study of their biology and the development of bioartificial livers. However, many challenges have to be overcome since hepatocytes rapidly lose their normal phenotype in vitro. We have recently demonstrated that human umbilical cord perivascular cells (HUCPVCs) are able to provide support to hepatocytes. In the present study we go further into exploring the effects that HUCPVCs have in the functional polarization, and both the internal and external organization, of hepatocytes. Also, we investigate HUCPVC–hepatocyte crosstalk by tracking both the effects of HUCPVCs on hepatocyte transcription factors and those of hepatocytes on the expression of hepatotrophic factors in HUCPVCs. Our results show that HUCPVCs maintain the functional polarity of hepatocytes ex vivo, as judged by the secretion of fluorescein into bile canaliculi, for at least 40 days. Transmission electron microscopy revealed that hepatocytes in coculture organize in an organoid-like structure embedded in extracellular matrix surrounded by HUCPVCs. In coculture, hepatocytes displayed a higher expression of C/EBPα, implicated in maintenance of the mature hepatocyte phenotype, and HUCPVCs upregulated hepatocyte growth factor and Jagged1 indicating that these genes may play important roles in HUCPVC–hepatocyte interactions.

Sirtuin deacylases: a molecular link between metabolism and immunity

Lysine deacetylation by the NAD(+)-dependent family of sirtuins has been recognized as an important post-translational modification regulating a wide range of cellular processes. These lysine deacetylases have attracted much interest based on their ability to promote survival in response to stress. Sirtuins require NAD(+) for their enzymatic activity, suggesting that these enzymes may represent molecular links between cell metabolism and several human disorders, including diabetes and cancer. Inflammation represents a pathological situation with clear connections to metabolism and aging in humans, raising the possibility that sirtuins may also play an important role during a normal and/or a pathological immune response. A growing body of data has confirmed the immunomodulatory properties of sirtuins, although often with contrasting and opposing conclusions. These observations will be summarized herein and the possible strategies that may lead to the development of novel therapeutic approaches to treat inflammation briefly discussed.

Topical niacinamide 4% and desonide 0.05% for treatment of axillary hyperpigmentation: a randomized, double-blind, placebo-controlled study

Background

Axillary hyperpigmentation is a frequent cause of cosmetic consultations in dark-skinned women from tropical areas, including Latin America. Currently, there is no widely accepted treatment for the disorder, but it is usually treated with bleaching agents because it is considered a variant of inflammatory hyperpigmentation. The purpose of this study was to assess the efficacy of niacinamide 4% and desonide 0.05% emulsions compared with placebo in the treatment of axillary hyperpigmentation.

Methods

Twenty-four women aged 19–27 years with hyperpigmented axillae (phototype III–V) were randomly assigned to receive the study treatments in the axillary region. Improvement was assessed at baseline, then clinically and by colorimetry 9 weeks later. Quantitative evaluation including melanin, inflammatory infiltrates, NKI/Beteb, CD1a, CD68, and collagen type IV content was performed by histochemistry and immunohistochemistry, assisted by computerized morphometric analysis.

Results

Both niacinamide and desonide induced significant colorimetric improvement compared with placebo; however, desonide showed a better depigmenting effect than niacinamide. A good to excellent response was achieved in 24% of cases for niacinamide, 30% for desonide, and 6% for placebo. We observed a marked disruption of the basal membrane in axillary hyperpigmentation and an inflammatory infiltrate that improved after treatment. Decreased pigmentation in the desonide-treated axillae was associated with recovery of disruption at the basal membrane.

Conclusion

Niacinamide and desonide showed depigmenting properties in women with axillary hyperpigmentation. These findings may be explained by their antimelanogenic and anti-inflammatory properties, respectively.

The multi-functional roles of GNMT in toxicology and cancer

Although glycine N-methyltransferase (GNMT) has been discovered for five decades, its function was not elucidated until recently. In this review, we discuss the multiple roles of GNMT in toxicology and cancer. Besides catalyzing the production of methylglycine (sarcosine) in one carbon metabolism pathway, GNMT was found to be able to bind a number of polycyclic aromatic hydrocarbons and inhibit DNA adducts formation. Moreover, GNMT exerts protective effects against the cytotoxicity and carcinogenicity of benzo(a)pyrene and aflatoxin B(1) in vitro and in vivo. Occupational study showed that workers who had genotypes with higher GNMT promoter activity may have lower content of oxidative damaged DNA products in their urine. In terms of cancer, recent studies using GNMT knockout mouse models demonstrated that GNMT deficiency has high penetrance in inducing the development of steatohepatitis and hepatocellular carcinoma. In terms of the mechanism, besides dysregulation of epigenetic modification, insights have been provided by recent identification of two novel proteins interacting with GNMT-DEPTOR and NPC2. These studies suggest that GNMT not only is involved in mTOR signaling pathway, but also plays an important role in the intracellular trafficking of cholesterol. The implication of these findings to the preventive medicine and translational research will be discussed.