Niacin Pretreatment Attenuates Ischemia and Reperfusion of Pancreas-induced Acute Pancreatitis and Remote Lung Injury Through Suppressing Oxidative Stress and Inflammation and Activation of SIRT1

Association between dietary intake of niacin and stroke in the US residents: evidence from national health and nutrition examination survey (NHANES) 1999-2018

Objective

This study aims to explore the association between niacin intake and stroke within a diverse, multi-ethnic population.

Methods

A stringent set of inclusion and exclusion criteria led to the enrollment of 39,721 participants from the National Health and Nutrition Examination Survey (NHANES). Two interviews were conducted to recall dietary intake, and the USDA's Food and Nutrient Database for Dietary Studies (FNDDS) was utilized to calculate niacin intake based on dietary recall results. Weighted multivariate logistic regression was employed to examine the correlation between niacin and stroke, with a simultaneous exploration of potential nonlinear relationships using restricted cubic spline (RCS) regression.

Results

A comprehensive analysis of baseline data revealed that patients with stroke history had lower niacin intake levels. Both RCS analysis and multivariate logistic regression indicated a negative nonlinear association between niacin intake and stroke. The dose-response relationship exhibited a non-linear pattern within the range of dietary niacin intake. Prior to the inflection point (21.8 mg) in the non-linear correlation between niacin intake and stroke risk, there exists a marked decline in the risk of stroke as niacin intake increases. Following the inflection point, the deceleration in the decreasing trend of stroke risk with increasing niacin intake becomes evident. The inflection points exhibit variations across diverse populations.

Conclusion

This investigation establishes a negative nonlinear association between niacin intake and stroke in the broader American population.

Niacin treatment prevents bone loss in iron overload osteoporotic rats via activation of SIRT1 signaling pathway

Recently, more and more studies have revealed that iron overload can lead to osteoporosis by inducing oxidative stress. Niacin (NAN), also known as nicotinate or vitamin B3, has been confirmed to possess potent antioxidative effects. In addition, very little is currently known about the protective effects of NAN on iron overload in osteoporotic bone tissue. Therefore, we aimed to evaluate the protective effect of niacin on iron overload-induced bone injury and to investigate the effect and underlying mechanisms of the niacin and iron overload on intracellular antioxidant properties. When MC3T3-E1 and RAW264.7 cells were cultured in the presence of ammonium ferric citrate(FAC), NAN therapy could increase the matrix mineralization and promote expression of osteogenic markers in MC3T3-E1, inhibit osteoclastic differentiation of RAW264.7 cells, while increasing intracellular reactive oxygen species (ROS) levels and strengthening mitochondrial membrane potential (MMP). In the ovariectomized (OVX) rat model, NAN had an obvious protective effect against iron-overloaded injury. Meanwhile, superoxide dismutase 2 (SOD2), intracellular antioxidant enzymes and silent information regulator type 1 (SIRT1), were up-regulated in response to NAN exposures in MC3T3-E1. Furthermore, SIRT1 inhibitor EX527 attenuated the protective effects of NAN. Results revealed that NAN could stimulate osteogenic differentiation, inhibit osteoclastic differentiation and markedly increased antioxidant properties in cells through the induction of SIRT1. Studies suggest that niacin is a promising agent for preventing bone loss in iron overload conditions.

Niacin modulates depressive-like behavior in experimental colitis through GPR109A-dependent mechanisms

AIMS

Depression is one of the common neurological comorbidities in patients with inflammatory bowel disease (IBD). The current study aimed to investigate the potential impact of niacin on colitis-induced depressive-like behavior in rats.

MATERIALS AND METHODS

Animals were given 5 % dextran sulfate sodium (DSS) in drinking water for one week to induce colitis. Niacin (80 mg/kg), with or without mepenzolate bromide (GPR109A blocker), was administered once per day throughout the experimental period. Rats were tested for behavioral changes using open field and forced swimming tests.

KEY FINDINGS

Niacin significantly ameliorated DSS-induced behavioral deficits and alleviated macroscopic and microscopic colonic inflammatory changes. It also augmented the hippocampal levels of ZO-1, occludin, and claudin-5 proteins, indicating the ability of niacin to restore the blood-brain barrier (BBB) integrity. Moreover, niacin decreased hippocampal IL-1ꞵ and NF-ĸB contents but increased GSH, Sirt-1, Nrf-2, HO-1 concentrations. All these beneficial effects were partially abolished by the co-administration of mepenzolate bromide.

SIGNIFICANCE

The neuroprotective effect of niacin against DSS-induced depressive-like behavior was partially mediated through GPR109A-mediated mechanisms. Such mechanisms are also involved in modulating neuronal oxidative stress and inflammation via Sirt-1/Nrf-2/HO-1 signaling pathways.

Electroacupuncture Pretreatment Exhibits Lung Protective and Anti-Inflammation Effects in Lipopolysaccharide-Induced Acute Lung Injury via SIRT1-Dependent Pathways

To investigate the effect of electroacupuncture (EA) on acute lung injury (ALI), a lipopolysaccharide (LPS) induced ALI mouse model was used in this study. Before receiving intratracheal LPS instillation, mice were given EA at ST36 for 7 days as a long-term treatment or one time as a short-term treatment. Lung histopathological examination, lung injury scores, lung wet/dry (W/D) ratio, and inflammatory cytokines included proinflammation factors such as TNF-α, IL-1β, and IL-6 and anti-inflammation factors such as IL-4 and IL-10 in serum and bronchoalveolar lavage fluid (BALF) were detected at the end of experiment. The results show that EA pretreatment ameliorated the lung damage and inflammatory response by LPS. In addition, we found that SIRT1 and its deacetylation of NF-κB were promoted after EA pretreatment in lung tissues. Meanwhile, the expression of angiotensin-converting enzyme 2 (ACE2) is also enhanced by EA pretreatment. Thus, the present findings suggest that EA could be a potential therapy of ALI.

Leonurine: A compound with the potential to prevent acute lung injury

Sepsis is an intense immune response to infection that contributes to the pathophysiological process of acute lung injury (ALI). Inflammation and oxidative stress serve an important role in the development of ALI. Leonurine (LEO) is a natural phenolic alkaloid extracted from Leonurus cardiaca, which possesses anti-inflammatory and antioxidative properties. Therefore, the aim of the present study was to explore the effect of LEO on sepsis-induced ALI and to investigate its underlying mechanism. MTT and Cell Counting Kit-8 assays were performed to measure cell viability. The levels of reactive oxygen species, lactate dehydrogenase and malondialdehyde, as well as the activity of superoxidase dismutase, were quantified using commercial assay kits. The expression levels of specific inflammatory cytokines were measured by using ELISA. In addition, western blotting was employed to assess the expression levels of cytokines, including TNF-α, IL-6, nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1. The findings demonstrated that LEO increased the viability of lipopolysaccharide (LPS)-stimulated BEAS-2B human lung epithelial cells in a dose-dependent manner. Additionally, LEO suppressed LPS-induced oxidative stress and inflammatory cytokine release in BEAS-2B cells. Treatment with Nrf2 inhibitor reversed the effects of LEO treatment on LPS-induced oxidative stress and inflammatory response in BEAS-2B cells. Taken together, the data of the present study indicated that LEO attenuated LPS-induced ALI through the inhibition of oxidative stress and inflammation regulated by the Nrf2 signaling pathway. Therefore, LEO may be a novel and effective agent for the prevention of sepsis-induced ALI.

Depleting microRNA-146a-3p attenuates lipopolysaccharide-induced acute lung injury via up-regulating SIRT1 and mediating NF-κB pathway

OBJECTIVE

The role of microRNAs (miRs) in acute lung injury (ALI) has been discussed. This study is to uncover the effects of miR-146a-3p/Sirtuin-1 (SIRT1)/Nuclear factor-kappa B (NF-κB) axis on ALI.

METHODS

Human normal lung epithelial cell line BEAS-2B was exposed to lipopolysaccharide (LPS) to establish an in vitro model of ALI. NF-κB expression, cell activity, apoptosis, inflammatory factors, oxidative stress indices were detected in LPS-induced BEAS-2B cells after miR-146a-3p was down-regulated or SIRT1 was up-regulated. ALI rat model was established and the NF-κB expression, wet/dry weight (W/D) ratio, pathological changes, pneumonocyte apoptosis, inflammatory factors, oxidative stress indices were detected in ALI rats after miR-146a-3p was down-regulated or SIRT1 was up-regulated. The target relationship between miR-146a-3p and SIRT1 was confirmed.

RESULTS

Reduced SIRT1 and raised miR-146a-3p  were found in LPS-induced BEAS-2B cells and ALI rats. SIRT1-overexpressing or  miR-146a-3p-underexpressing up-regulated NF-κB expression, promoted viability and inhibited apoptosis of LPS-induced BEAS-2B cells in vitro, and increased NF-κB expression, down-regulated the W/D ratio, attenuated pathological changes, suppressed apoptosis, and alleviated inflammatory response and oxidative stress in the lung of ALI rats. MiR-146a-3p directly binds to the 3'UTR of SIRT1 mRNA.

CONCLUSION

Depleting miR-146a-3p improves ALI through up-regulating SIRT1 and mediating NF-κB pathway.

Effects of Bacterial Translocation and Autophagy on Acute Lung Injury Induced by Severe Acute Pancreatitis

Aim

To reveal the role of bacterial translocation (BT) and autophagy in severe acute pancreatitis-induced acute lung injury (SAP-ALI).

Methods

Rats were separated into a control (sham-operation) group (n = 10) and a SAP group (n = 10) and a SAP group (

Results

Levels of TNF-α, IL-6, lipase, and amylase in the SAP group were significantly higher than those in the control group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (

Conclusions

BT can aggravate SAP-ALI with the increasing oxidative stress level, which may be related to the decrease of autophagy level.

Mesenchymal stem cells induce dendritic cell immune tolerance via paracrine hepatocyte growth factor to alleviate acute lung injury

BACKGROUND

Mesenchymal stem cells (MSCs) have been shown to alleviate acute lung injury (ALI) via paracrine hepatocyte growth factor (HGF) and to induce the differentiation of dendritic cells (DCs) into tolerogenic dendritic cells (DCregs) and participate in the immune response. However, whether MSCs induce the production of DCregs by secreting HGF to alleviate early ALI remains unclear. We observed that the protective effect of mouse bone marrow-derived MSCs against lipopolysaccharide (LPS)-induced ALI was achieved by inducing mature DCs (mDCs) to differentiate into DCregs, and its mechanism is related to the activation of the HGF/Akt pathway.

METHODS

MSCs or MSCs with overexpression or knockdown of HGF were cocultured with DCs derived from mouse bone marrow using a Transwell system for 3 days. Moreover, we used MSCs or MSCs with overexpression or knockdown of HGF to treat LPS-induced ALI mice for 24 h. Flow cytometry was performed to measure the phagocytosis, accumulation, and maturation of DCs, as well as proliferation of T cells. Lung injury was estimated by lung wet weight to body weight ratio (LWW/BW) and histopathological analysis. Furthermore, we used the Akt inhibitor MK-2206 in a coculture system to elucidate the role of the HGF/Akt pathway in regulating the differentiation of DCs into regulatory DCs and relieving lung injury in early ALI mice.

RESULTS

Immature DCs (imDCs) were induced to mature after 24 h of LPS (50 ng/ml) stimulation. MSCs or HGF induced the differentiation of mDCs into regulatory DCs characterized by low expression of MHCII, CD86, and CD40 molecules, strong phagocytic function, and the ability to inhibit T cell proliferation. The effect of MSCs on DCregs was enhanced with the increase in HGF secretion and was weakened with the decrease in HGF secretion. DCregs induced by recombinant HGF were attenuated by the Akt inhibitor MK-2206. Lung DC aggregation and mDC ratio increased in LPS-induced ALI mice, while treatment with MSCs decreased lung DC aggregation and maturation and alleviated lung pathological injury. High expression of the HGF gene enhanced the above effect of MSCs, while decreased expression of HGF weakened the above effect of MSCs.

CONCLUSIONS

MSCs alleviate early ALI via paracrine HGF by inducing mDCs to differentiate into regulatory DCs. Furthermore, the mechanism of HGF-induced differentiation of mDCs into DCregs is related to the activation of the Akt pathway.