Niacin Pretreatment Attenuates Lung Ischemia and Reperfusion-Induced Pulmonary Barrier Function Impairment by Reducing Oxidative Stress and Activating SIRT1 in an Isolated-Perfused Rat Lung Model

The potential prophylactic and therapeutic impacts of niacin on ischemia/reperfusion injury of testis

INTRODUCTION

The testicular ischemia-reperfusion (I/R) injury is characterized by the excessive aggregation of un-scavenged reactive oxygen species, leading to the heightened levels of oxidative stress. This phenomenon plays a pivotal role in the pathophysiology of testicular torsion damage.

OBJECTIVE

The current study aimed to detect the prophylactic and therapeutic effects of niacin on testicular I/R injury.

STUDY DESIGN

Twenty-four healthy adult male Sprague Dawley rats were randomly allocated into three groups as follows: (1) sham group, (2) torsion/detorsion (T/D) group, and (3) treatment group which received 200 mg/kg niacin along with testicular T/D. Torsion/detorsion was induced by 2 h of torsion followed by 10 days of reperfusion period. In the treatment group, niacin was injected 30 min before the reperfusion period intraperitoneally and continued for 10 days by oral gavage.

RESULTS

T/D was associated with marked decreases in terms of sperm count, viability, and kinematic parameters versus the sham group (P < 0.05), which niacin significantly reverted the kinematic parameters (P < 0.05). I/R injury caused a significant increase in the number of abnormal epididymal sperms compared to the sham group (P < 0.05). Niacin decreased the epididymal sperm abnormality significantly compared to the T/D group (P < 0.05). Tissue abnormalities in T/D group, such as edema, hyperemia, inflammation, and necrosis were completely visible histopathologically, while the histological changes in the niacin-treated group were better than those in the T/D group. Regarding the pathological parametric evaluations, I/R injury significantly reduced the mean testicular biopsy score (MTBS), germinal epithelial cell thickness (GECT), and mean seminiferous tubular diameter (MSTD), and increased the tubular hypoplasia/atrophy (THA) compared to the sham group (P < 0.05), which niacin treatment significantly improved the MTBS and GECT compared to the T/D group (P < 0.05). T/D significantly increased the oxidative stress index (OSI) and lipid peroxidation (MDA) (P < 0.05). Niacin significantly reduced the OSI and MDA levels compared to the T/D group (P < 0.05).

DISCUSSION

The current study found that niacin has preventive/therapeutic effects against the elevation of oxidative stress markers and depletion of antioxidants during I/R injury. Following administration of niacin, a reduction in histologic injury was observed in rats. In our study, we showed the antioxidant properties of niacin and its capacity to protect against I/R damage.

CONCLUSION

The findings of the present investigation revealed that niacin, as an antioxidant agent, can suppress the oxidative stress induced by testicular I/R injury, and can be used as a supplementary agent in the treatment of those undergoing testicular torsion surgery.

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.

Protective Effect of the SIRT1-Mediated NF-κB Signaling Pathway against Necrotizing Enterocolitis in Neonatal Mice

OBJECTIVE

 To discover the mechanism of the sirtuin 1 (SIRT1)-mediated nuclear factor-κB (NF-κB) pathway in the protection against necrotizing enterocolitis (NEC) in neonatal mice.

MATERIALS AND METHODS

 Neonatal mice were treated with EX527 (an inhibitor of SIRT1) and/or pyrrolidine dithiocarbamate (PDTC, an inhibitor of NF-κB). The survival rate of the mice was recorded. Hematoxylin and eosin (HE) staining was performed to observe the pathological changes in the intestines. Furthermore, western blotting, enzyme-linked immunosorbent assay, and real-time quantitative polymerase chain reaction were conducted to measure the protein and gene expression, while corresponding kits were used to detect the levels of oxidative stress indicators.

RESULTS

 PDTC increased the survival rate of NEC mice. When compared with the NEC+ EX527 + PDTC group, the histological NEC score was higher in the NEC + EX527 group but lower in the NEC + PDTC group. SIRT1 expression in the intestines of NEC mice was downregulated, with an increase in p65 nuclear translocation. Additionally, malondialdehyde increased and glutathione peroxidase decreased in the intestines of NEC mice, with the upregulation of interleukin (IL)-6, IL-1β, and tumor necrosis factor-α, as well as the downregulation of ZO-1, occludin, and claudin-4 in the intestines. However, the above changes could be improved by PDTC, which could be further reversed by EX527.

CONCLUSION

 SIRT1 can mitigate inflammation and the oxidative stress response and improve intestinal permeability by mediating the NF-κB pathway, playing an important role in the alleviation of NEC.

Artesunate reduces sepsis-mediated acute lung injury in a SIRT1-dependent manner

Introduction

Sepsis-mediated acute lung injury (ALI) is a critical clinical condition. Artesunate (AS) is a sesquiterpene lactone endoperoxide that was discovered in Artemisia annua, which is a traditional Chinese herb. AS has a broad set of biological and pharmacological actions; however, its protective effect on lipopolysaccharide (LPS)-induced ALI remains unclear.

Methods

LPS-mediated ALI was induced in rats through bronchial LPS inhalation. Then NR8383 cells were treated with LPS to establish an in vitro model. Further, we administered different AS doses in vivo and in vitro.

Results

AS administration significantly decreased LPS-mediated pulmonary cell death and inhibited pulmonary neutrophil infiltration. Additionally, AS administration increased SIRT1 expression in pulmonary sections. Administration of a biological antagonist or shRNA-induced reduction of SIRT1 expression significantly inhibited the protective effect of AS against LPS-induced cellular injury, pulmonary dysfunction, neutrophil infiltration, and apoptosis. This demonstrates that enhanced SIRT1 expression is crucially involved in the observed protective effects.

Conclusion

Our findings could suggest the use of AS for treating lung disorders through a mechanism involving SIRT1 expression.

Effect of Different Doses of Propofol on Pulmonary Function and Inflammatory Response in Patients with Lung Ischemia Reperfusion Injury Induced by One-Lung Ventilation Based on Big Data Analysis

Objective

To analyze the effect of different doses of propofol on pulmonary function and inflammatory response in patients with lung ischemia reperfusion injury (LIRI) induced by one-lung ventilation (OLV) based on big data analysis.

Methods

A retrospective study was performed on 105 patients who underwent lobectomy in our hospital (January 2018 to January 2022). According to the doses of propofol, they were split into low-dose group (LDG), middle-dose group (MDG), and high-dose group (HDG), which received the continuous micropump infusion of propofol at the doses of 2 mg/(kg·h), 5 mg/(kg·h), and 10 mg/(kg·h) after induction, respectively, with 35 cases in each group. The indexes, such as the pulmonary function and inflammatory factors of patients, at different times were compared. The logistic regression analysis was performed according to the occurrence of LIRI.

Results

With no notable difference at T0 among the three groups (P > 0.05), the Cdyn levels significantly decreased at T1 (P < 0.05) and gradually increased at T2. The Cdyn levels at T1 and T2 were remarkably higher in HDG and MDG than in LDG (P < 0.05). With no notable differences at T0 and T1 among the three groups (P > 0.05), the P_A-aO₂ levels and RI values at T2 in MDG and HDG were lower compared with LDG (P < 0.05). The RI values at T1 and T2 in HDG were higher compared with MDG, with no obvious difference (P > 0.05). The OI levels at T1 and T2 in HDG were lower compared with the other two groups (P < 0.05), and the OI levels at T1, T2, and T3 in LDG were higher compared with MDG, with no obvious difference (P > 0.05). The TNF-α and ICAM-1 levels at T1 and T2 in MDG and HDG were lower compared with LDG, with no obvious difference between MDG and HDG (P > 0.05). Compared with LDG, the MDG and HDG at T1 and T2 had lower MDA levels (P < 0.05) and higher SOD levels (P < 0.05). Logistic regression analysis showed that Cdyn, P_A-aO₂, and OLV time were independent risk factors for LIRI in patients undergoing lobectomy.

Conclusion

Propofol has a good protective effect on lung function in patients with OLV-induced LIRI. Appropriately increasing the dose of propofol can effectively improve the local cerebral hypoxia and lung compliance of patients and reduce the inflammatory response and oxidative stress response, with 5 mg/(kg·h) as the clinical reference. Preoperative assessment and preparation should be made for patients, close attention should be paid to risk factors, such as Cdyn and P_A-aO₂, and OLV time should be controlled.

Niacin Alleviates Dairy Cow Mastitis by Regulating the GPR109A/AMPK/NRF2 Signaling Pathway

Mastitis is one of three bovine diseases recognized as a cause of substantial economic losses every year throughout the world. Niacin is an important feed additive that is used extensively for dairy cow nutrition. However, the mechanism by which niacin acts on mastitis is not clear. The aim of this study is to investigate the mechanism of niacin in alleviating the inflammatory response of mammary epithelial cells and in anti-mastitis. Mammary glands, milk, and blood samples were collected from mastitis cows not treated with niacin (n = 3) and treated with niacin (30 g/d, n = 3) and healthy cows (n = 3). The expression of GPR109A, IL-6, IL-1β, and TNF-α in the mammary glands of the dairy cows with mastitis was significantly higher than it was in the glands of the healthy dairy cows. We also conducted animal experiments in vivo by feeding rumen-bypassed niacin. Compared with those in the untreated mastitis group, the somatic cell counts (SCCs) and the expression of IL-6, IL-1β, and TNF-α in the blood and milk were lower. In vitro, we isolated the primary bovine mammary epithelial cells (BMECs) from the mammary glands of the healthy cows. The mRNA levels of IL-6, IL-1β, TNF-α, and autophagy-related genes were detected after adding niacin, shRNA, compound C, trans retinoic acid, 3-methyladenine to BMECs. Then GPR109A, AMPK, NRF-2, and autophagy-related proteins were detected by Western blot. We found that niacin can activate GPR109A and phosphorylate AMPK, and promote NRF-2 nuclear import and autophagy to alleviate LPS-induced inflammatory response in BMECs. In summary, we found that niacin can reduce the inflammatory response of BMECs through GPR109A/AMPK/NRF-2/autophagy. We also preliminarily explored the alleviative effect of niacin on mastitis in dairy cows.