Nicotinamide enhances apoptosis of G(M)-CSF-treated neutrophils and attenuates endotoxin-induced airway inflammation in mice

Virtual Drug Repositioning as a Tool to Identify Natural Small Molecules That Synergize with Lumacaftor in F508del-CFTR Binding and Rescuing

Cystic fibrosis is a hereditary disease mainly caused by the deletion of the Phe 508 (F508del) of the cystic fibrosis transmembrane conductance regulator (CFTR) protein that is thus withheld in the endoplasmic reticulum and rapidly degraded by the ubiquitin/proteasome system. Cystic fibrosis remains a potentially fatal disease, but it has become treatable as a chronic condition due to some CFTR-rescuing drugs that, when used in combination, increase in their therapeutic effect due to a synergic action. Also, dietary supplementation of natural compounds in combination with approved drugs could represent a promising strategy to further alleviate cystic fibrosis symptoms. On these bases, we screened by in silico drug repositioning 846 small synthetic or natural compounds from the AIFA database to evaluate their capacity to interact with the highly druggable lumacaftor binding site of F508del-CFTR. Among the identified hits, nicotinamide (NAM) was predicted to accommodate into the lumacaftor binding region of F508del-CFTR without competing against the drug but rather stabilizing its binding. The effective capacity of NAM to bind F508del-CFTR in a lumacaftor-uncompetitive manner was then validated experimentally by surface plasmon resonance analysis. Finally, the capacity of NAM to synergize with lumacaftor increasing its CFTR-rescuing activity was demonstrated in cell-based assays. This study suggests the possible identification of natural small molecules devoid of side effects and endowed with the capacity to synergize with drugs currently employed for the treatment of cystic fibrosis, which hopefully will increase the therapeutic efficacy with lower doses.

Metabolomics-based molecular signatures reveal the toxic effect of co-exposure to nitrosamines in drinking water

Nitrosamines, a group of emerging nitrogenous pollutants, are ubiquitously found in the drinking water system. However, less is known about how systemic biological responses resist or tolerate nitrosamines, especially long-term co-exposure at low concentrations. In this study, untargeted metabolomics was used to investigate the metabolic perturbations in human esophageal epithelial Het-1A cells induced by a mixture of nine common nitrosamines in drinking water at environmentally relevant, human-internal-exposure, and genotoxic concentrations. Generally, the disrupted metabolic spectrum became complicated with nitrosamines dose increasing. Notably, two inflammation-associated pathways, namely, cysteine (Cys) and methionine (MET) metabolism, and nicotinate and nicotinamide metabolism, changed significantly under the action of nitrosamines, even at the environmentally relevant level. Furthermore, targeted metabolomics and molecular biology indicators in cells were identified in mice synchronously. For one thing, the up-regulated Cys and MET metabolism provided methyl donors for histone methylation in the context of pro-inflammatory response. For another, the down-regulated NAD⁺/NADH ratio inhibited the deacetylation of NF-кB p65 and eventually activated the NF-кB signaling pathway. Taken collectively, the metabolomics molecular signatures were important indicative markers for nitrosamines-induced inflammation. The potential crosstalk between the inflammatory cascade and metabolic regulation also requires further studies. These findings suggest that more attention should be paid to long-term co-exposure at low concentrations in the control of nitrosamines pollution in drinking water. Additionally, this study also highlights a good prospect of the combined metabolomic-molecular biology approach in environmental toxicology.

Fate of PEGylated antibody fragments following delivery to the lungs: Influence of delivery site, PEG size and lung inflammation

Pulmonary administration of anti-cytokine antibodies offers a targeted therapy in asthma. However, the rapid elimination of proteins from the lungs limits the efficacy of inhaled medications. PEGylation has been shown to increase the residence time of anti-interleukin (IL)-17A and anti-IL-13 antibody fragments in the lungs and to improve their therapeutic efficacy. Yet, little is known about the factors that affect the residence time of PEGylated antibody fragments in the lungs following pulmonary delivery. In this study, we showed that the molecular weight of polyethylene glycol (PEG), 20kDa or 40kDa, had a moderate effect on the residence time of an anti-IL-17A Fab' fragment in the lungs of mice. By contrast, the site of delivery of the anti-IL-17A and anti-IL-13 Fab' fragments within the lungs had a major impact on their residence time, with the deeper the delivery, the more prolonged the residence time. The nature of the Fab' fragment had an influence on its residence time as well and the anti-IL-17A Fab' benefited more from PEGylation than the anti-IL-13 Fab' did. Acute lung inflammation slightly shortened the residence time of the anti-IL-17A and anti-IL-13 Fab' fragments in the lungs but PEGylation was able to prolong their presence in both the healthy and inflamed lungs. Antibody fragments were predominately located within the airway lumen rather than the lung parenchyma. Transport experiments on monolayers of Calu-3 cells and studies of fluorescence recovery after photobleaching in respiratory mucus showed that mechanisms involved in the prolonged presence of PEGylated Fab' in the airway lumen might include binding to the mucus, reduced uptake by respiratory cells and reduced transport across lung epithelia. Finally, using I¹²⁵-labeled anti-IL-17A Fab', we showed that the protein fragment hardly penetrated into the lungs following subcutaneous injection, as opposed to pulmonary delivery.

Cytochrome c modulates the mitochondrial signaling pathway and polymorphonuclear neutrophil apoptosis in bile duct-ligated rats

It has been observed that polymorphonuclear neutrophils (PMN) increase in number and function during obstructive jaundice (OJ). However, the precise mechanisms underlying PMN apoptosis during OJ remain poorly understood. The aim of the present study was to investigate the modulation of cytochrome c (Cytc) on the mitochondrial signaling pathway in bile duct-ligated (BDL) rats and the effect on PMN apoptosis following the intravenous administration of Cytc. Rats were randomly divided into four groups: A control group, a sham group, a BDL group and a BDL + Cytc group (rats with common bile duct ligation as well as Cytc intravenous injection). Blood samples were collected from the inferior vein cava for biochemical analysis and separation of the PMN. PMN apoptosis was evaluated using flow cytometry. The mitochondrial membrane potential (ΔΨm) of PMN was detected by rhodamine-123 staining. The Cytc protein expression levels were examined using western blotting. PMN mitochondria were observed using transmission electron microscopy. The results of the present study revealed that the PMN apoptosis rate in rats decreased gradually from 12 to 72 h following BDL to levels that were significantly lower than those of the control group and the sham group. Compared with the corresponding time point of the BDL group, the BDL + Cytc group showed a significantly increased PMN apoptosis rate. The mean fluorescence intensity (MFI) of ΔΨm decreased from 12 to 72 h following BDL, and was significantly increased compared with the control and sham groups. MFI in the BDL + Cytc group was higher compared with that in the BDL group. Cytc expression levels increased in the mitochondria and decreased in the cytoplasm from the 12 to 72 h in the BDL group, which was significantly different from that in the control and sham groups at the corresponding time points. Compared with the BDL group, Cytc expression levels in the cytoplasm for the BDL + Cytc group tended to gradually and significantly increase. Morphological changes in PMN mitochondria were marginal in BDL rats and marked in the BDL + Cytc group. In the BDL rats, PMN apoptosis was inhibited, a process induced by the mitochondrial apoptotic signaling pathway in which Cytc has an important role. High ΔΨm in the mitochondria and decreased Cytc expression levels in the cytoplasm result in PMN apoptosis inhibition. Intravenous injection of Cytc may help compensate for the lack of Cytc proteins in the cytoplasm, inducing PMN apoptosis following BDL.

Murine models of cardiovascular comorbidity in chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiovascular disease (CVD). Currently, COPD patients with atherosclerosis (i.e., the most important underlying cause of CVD) receive COPD therapy complemented with standard CVD therapy. This may, however, not be the most optimal treatment. To investigate the link between COPD and atherosclerosis and to develop specific therapeutic strategies for COPD patients with atherosclerosis, a substantial number of preclinical studies using murine models have been performed. In this review, we summarize the currently used murine models of COPD and atherosclerosis, both individually and combined, and discuss the relevance of these models for studying the pathogenesis and development of new treatments for COPD patients with atherosclerosis. Murine and clinical studies have provided complementary information showing a prominent role for systemic inflammation and oxidative stress in the link between COPD and atherosclerosis. These and other studies showed that murine models for COPD and atherosclerosis are useful tools and can provide important insights relevant to understanding the link between COPD and CVD. More importantly, murine studies provide good platforms for studying the potential of promising (new) therapeutic strategies for COPD patients with CVD.

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.

Nicotinamide induces apoptosis of F9 mouse teratocarcinoma stem cells by downregulation of SATB1 expression

The aim of this study was to decide whether nicotinamide (NA) could induce apoptosis of F9 mouse teratocarcinoma stem cells (MF9) by downregulation of special AT-rich sequence binding protein 1 (SATB1) expression. We used different concentrations of NA (0, 1.5, 2, and 2.5 mmol/L) to treat MF9 cells and analyze SATB1 expression by RT-qPCR and Western blotting; in addition, the cell proliferation was detected in a microplate reader with Cell Counting Kit-8 (CCK-8), and the cell cycle and apoptosis were analyzed using flow cytometry. We found that the expression of SATB1 was decreased significantly in NA-treated groups than in the control group, and its expression level was inversely related to the NA concentration. In addition, CCK-8 analysis showed that NA significantly inhibited the proliferation of MF9 cells, and flow cytometry showed that NA blocked MF9 cells to G1 phase and significantly promoted apoptosis in any treated groups. To confirm the results, we constructed small interference RNA (siRNA) targeting at mouse SATB1 and transferred into MF9 cells. The results indicated that the expression of SATB1 in both mRNA and protein levels was significantly decreased after cells transferred with siRNA sequence for 48 h, the proliferation of MF9 cells was significantly inhibited, and most of MF9 cells were blocked at G1 phase, and the apoptosis rate was increased obviously. The results showed that NA could inhibit the proliferation and induce apoptosis of MF9 cells. These findings might be used as an efficient candidate for teratocarcinoma therapy.

Protective effects of nicotinamide against acetaminophen-induced acute liver injury

Nicotinamide (NAM), the amide form of vitamin B3, is involved in a wide range of biological processes. Recent evidence revealed the anti-inflammatory and anti-oxidant properties of NAM and suggests it may be used as a novel strategy in the prevention of acute liver injury. In the present study, we investigated the potential protective effects of NAM on acetaminophen (APAP)-induced acute liver injury in mice. Mice were treated with NAM at 400mg/kg 30 min before or after administration of APAP at a hepatotoxic dose of 400mg/kg body weight via intraperitoneal injection. Liver injury and the expression of inflammation-related molecules were determined by histological examination and biochemical analysis, respectively. In addition, the survival rate of mice was assessed after APAP administration. Pretreatment with NAM for 30 min significantly decreased plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and malondialdehyde (MDA), and diminished histopathologic evidence of hepatic toxicity in mice following APAP administration. Similarly, posttreatment with NAM also decreased plasma ALT and AST levels in APAP-administrated mice. Furthermore, both pretreatment and posttreatment with NAM prolonged the survival rate of acute liver injury mice, accompanied by a significant reduction in the plasma levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), and interleukin-6 (IL-6). Together, these findings suggest that NAM possesses protective effects on APAP-induced liver injury, which may involve the anti-inflammatory action.

Therapeutic benefits of the group B3 vitamin nicotinamide in mice with lethal endotoxemia and polymicrobial sepsis

Nicotinamide (NAM) is a group B3 vitamin involved in a wide range of biological processes. Recently, the anti-inflammatory properties of NAM have been revealed. In this study, we investigated the therapeutic effects of NAM in murine models of endotoxemia and sepsis. Endotoxemic liver injury was induced by intraperitoneal injection of lipopolysaccharide (LPS) into D-galactosamine (D-Gal)-sensitized mice. Lethal endotoxemia was induced by intraperitoneal administration of LPS at a dose of 20 mg/kg. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP). In mice challenged with LPS/D-Gal, treatment with NAM significantly deceased serum aminotransferases level and alleviated hepatic lesions. NAM also reduced serum tumor necrosis factor-α level and attenuated apoptosis in liver, as assessed by terminal deoxynucleotidyl transferase-mediated nucleotide nick end labeling (TUNEL) staining and measurements of caspases activities. Survival analysis indicated that NAM reduced the mortality rate of LPS/D-Gal-challenged mice. In mice with lethal endotoxemia, NAM reduced serum level of pro-inflammatory cytokines and multiple organ damage as evidence by improved morphological lesion, reduced lung wet to dry ratio as well as decreased serum level of aminotransferase and blood urea nitrogen. In survival analysis, treatment with NAM increased the survival rate of mice with lethal endotoxemia or CLP-induced polymicrobial sepsis. Taken together, treatment with NAM might provide therapeutic benefits in sepsis, which attenuated inflammatory injury and improved the survival rate.