The involvement of oxidative stress and the TLR4/NF-κB/NLRP3 pathway in acute lung injury induced by high-altitude hypoxia.

This study investigated the effect of oxidative stress and the TLR4/NF-κB/NLRP3 pathway on the pathogenesis of acute lung injury (ALI) induced by high-altitude hypoxia. Rats were placed in an animal hyperbaric oxygen chamber to establish a rat model of ALI induced by high-altitude hypoxia after treatment with N-acetylcysteine (NAC; a reactive oxygen species [ROS] inhibitor) or/and MCC950 (an NLPR3 inflammasome inhibitor). After modeling, the wet-to-dry weight ratio (W/D) of rat lung tissues was calculated. In lung tissues, ROS levels were detected with immunofluorescence, the enzyme activity was tested with the kit, and the expression of TLR4/NF-κB/NLRP3 pathway-related genes and proteins was measured with western blotting and qRT-PCR. The levels of inflammatory factors in the serum were quantified with ELISA. After modeling, rats showed significantly increased W/D, ROS levels, and Malondialdehyde (MDA) concentrations and markedly diminished Superoxide dismutase (SOD) and Glutathione (GSH) concentrations in lung tissues (all P < 0.01), accompanied by substantially enhanced serum levels of TNF-α, IL-6, and IL-1β, significantly reduced serum levels of IL-10, and remarkably augmented TLR4, NLRP3, p-NF-κB p65, NF-κB p65 mRNA, and Caspase-1 expression in lung tissues (all P < 0.01). Furthermore, treatment with NAC or MCC950 alone or in combination prominently lowered the W/D of lung tissues (P < 0.01), serum levels of TNF-α (P < 0.05), IL-6 (P < 0.05), and IL-1β (P < 0.01), and NF-κB p65 expression and phosphorylation (P < 0.05, P < 0.01) while significantly increasing SOD and GSH concentrations (P < 0.05, P < 0.01) and serum levels of IL-10 (P < 0.01) in modeled rats. Meanwhile, treatment of NAC alone or combined with MCC950 significantly reduced MDA concentration and ROS levels (P < 0.05, P < 0.01) in modeled rats, and treatment of MCC950 alone or combined with NAC considerably declined TLR4, NLRP3, and Caspase-1 expression in modeled rats (P < 0.05, P < 0.01). Inhibition of oxidative stress and the TLR4/NF-κB/NLRP3 pathway can ameliorate ALI in rats exposed to high-altitude hypoxia.

Cao W ，Zeng Y ，Su Y ，Gong H ，He J ，Liu Y ，Li C ... -  《-》

Hypercapnia promotes NLRP3 inflammasome activation in microglia by activating P2X7R after lipopolysaccharide-induced activation of the TLR4/NF-κB signaling pathway.

Sepsis is an uncontrolled inflammatory response to infection and is closely associated with the occurrence of acute respiratory distress syndrome (ARDS). Low tidal volume lung ventilation and permissive hypercapnia is a recognized therapy for ARDS. However, whether permissive hypercapnia aggravates sepsis-associated encephalopathy (SAE) remains unclear. The present study investigated whether hypercapnia contributed to the development of SAE through the purinergic 2X7 receptor (P2X7R) by activating the Nod-like receptor protein 3 (NLRP3) inflammasome in sepsis. The SAE model was established by intracranial injection of lipopolysaccharide (LPS) (1 μg/ml, 5 μl) in C57BL/6 mice. Hypercapnia was induced by mechanical ventilation with a high concentration of CO2 (5 % CO2, 21 % O2 and 74 % N2) in vivo. Toll-like receptor 4 (TLR4) and P2X7R knockout (KO) mice were employed in the study, while in vitro, BV2 microglial cells were treated with LPS or a high concentration of CO2 (15 % CO2 + 20 % O2). Immunofluorescence and western blot analysis were used to assess the expression levels of TLR4, NF-κB, phosphorylated (p)-NF-κB, P2X7R, pro-caspase-1, caspase-1, pro-IL-1β, IL-1β, pro-IL-18 and IL-18. ATP levels in the cell culture medium were detected by fluorometric assay. The results revealed that, compared with the sham group, the expression levels of TLR4, p-NF-κB, pro-IL-1β, pro-IL-18 and NLRP3 were significantly upregulated in the LPS and LPS + hypercapnia groups, but not in the hypercapnia group. Although the expression levels of caspase-1, IL-1β and IL-18 were increased slightly in the LPS group, their upregulation was more pronounced in the LPS + hypercapnia group, and it was suppressed when TLR4 was knocked out. Furthermore, P2X7R expression and ATP levels in the cell culture medium remained unchanged in the LPS group compared with the sham group but were remarkably increased both in the hypercapnia and LPS + hypercapnia groups. Additionally, P2X7R KO restrained the caspase-1, IL-1β and IL-18 increased induced by LPS injected intracranially and hypercapnia. In conclusion, LPS induced the priming step of NLRP3 inflammasome activation, but had little effect on the activation step, while hypercapnia played an important role in the activation step through P2X7R, depending on the priming step stimulated by LPS.

Ding H ，Zhang S ，Li Z ，Zeng J ，Zeng H ... -  《-》

Mechanism of activation of TLR4/NF-κB/NLRP3 signaling pathway induced by heat stress disrupting the filtration barrier in broiler.

High-temperature environment can cause acute kidney injury affecting renal filtration function. To study the mechanism of renal injury caused by heat stress through activates TLR4/NF-κB/NLRP3 signaling pathway by disrupting the filtration barrier in broiler chickens. The temperature of broilers in the TN group was maintained at 23 ± 1 °C, and the HS group temperature was maintained at 35 ± 1℃ from the age of 21 days, and the high temperature was 10 h per day, and one broiler from each replicate group at the age of 35 and 42 days was selected for blood sampling, respectively. The ELISA results demonstrated that in comparison to the TN group, serum CORT content of broilers in the HS group was all remarkably elevated (P < 0.01); the levels of IL-6 and TNF-α in the serum were remarkably elevated (P < 0.05 or P < 0.01); serum CAT and SOD activities were all remarkably reduced (P < 0.05 or P < 0.01), and serum LDH activity and MDA content were all remarkably decreased (P < 0.05); serum BUN and CRE levels were remarkably elevated (P < 0.01). Pathological sections and transmission electron microscopy demonstrated that the structure of the renal filtration barrier in the HS group damaged gradually with the prolongation of heat stress in comparison to the TN group, but the damage was reduced at 42 days of age; the levels of TLR4, MyD88, NF-κB, NF-κB-p65, NLRP3, caspase-1 and IL-1β mRNAs were all up-regulated (P < 0.05 or P < 0.01) in renal tissues of the HS group, indicating that heat stress caused damage to the morphological structure and function of the renal filtration barrier and that TLR4/NF-κB/NLRP3 pathway was also affected by heat stress, leading to increased activity (P < 0.05 or P < 0.01). It demonstrated that heat stress caused detrimental effects on both the morphological structure and function of the renal filtration barrier, and the initiation of the TLR4/NF-κB/NLRP3 signaling pathway exacerbated the inflammatory damage, leading to increased thermal damage to renal tissues and glomerular filtration barriers; however, with the prolongation of heat stress, broilers gradually developed heat tolerance, and the damage to the renal tissues and filtration barriers triggered by heat stress was mitigated.

Dong HL ，Wu XY ，Wang FY ，Chen HX ，Feng SL ，Zhou CY ，Zhao ZQ ，Si LF ... -  《BMC Veterinary Research》

Glycyrrhizin alleviates BoAHV-1-induced lung injury in guinea pigs by inhibiting the NF-κB/NLRP3 Signaling pathway and activating the Nrf2/HO-1 Signaling pathway.

Varicellovirus bovinealpha 1 (BoAHV-1) is a significant pathogen responsible for respiratory disease in cattle, capable of inducing lung damage independently or co-infection with bacteria. The widespread spread of BoAHV-1 in cattle herds has caused substantial economic losses to the cattle industry. The pathogenic mechanisms of BoAHV-1 are often relevant to robust inflammatory responses, increased oxidative burden, and the initiation of apoptosis. Glycyrrhizin (GLY) is a small-molecule triterpenoid saponin compound obtained from the herb liquorice, which has a broad spectrum of pharmacological properties such as antiviral, anti-inflammatory, and antioxidant effects. Furthermore, GLY regulates lung physiology by modulating oxidative stress, inflammatory response, and cell apoptosis through interference with the NF-κB/NLRP3 and Nrf2/HO-1 Signaling pathways. However, the potential of GLY to mitigate lung injury induced by BoAHV-1 and its underlying mechanism remains unclear. Therefore, in this study, we investigated the protective effect of GLY against pulmonary injury induced by BoAHV-1 in a guinea pig model by reducing viral load and suppressing the inflammatory response, oxidative stress, and apoptosis. The results of this study demonstrated that GLY exerted a protective effect against BoAHV-1-induced lung injury in guinea pigs. Specifically, GLY reduced the levels of pro-inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and interleukin (IL)-8 in guinea pig tissues while suppressing the expression of Caspase-1. Additionally, GLY reduced BoAHV-1 load and the number of TUNEL-positive lung cells in guinea pig lungs while inhibiting Caspase 3 protein expression. Furthermore, GLY significantly enhanced lung antioxidant capacity by increasing superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activity while simultaneously reducing malondialdehyde (MDA) levels. Lung histological observation and score further validated the protective effect of GLY on BoAHV-1-induced lung injury. Furthermore, we observed that the expression of phosphorylated NF-κB p65 (p-NF-κB p65) and NLRP3 proteins in the lung tissue of BoAHV-1-infected guinea pigs decreased after GLY treatment while the expression of Nrf2 and HO-1 proteins increased. These results indicated that GLY inhibited the NF-κB/NLRP3 Signaling pathway and activated the Nrf2/HO-1 Signaling pathway during BoAHV-1 infection. Ultimately, our findings demonstrated that GLY alleviates BoAHV-1-induced inflammation response, oxidative stress, and cell apoptosis by inhibiting the NF-κB/NLRP3 Signaling pathway and activating the Nrf2/HO-1 Signaling pathway to protect guinea pigs from lung injury caused by BoAHV-1. Ultimately, our findings demonstrated that GLY alleviates BoAHV-1-induced inflammation response, oxidative stress, and cell apoptosis by inhibiting the NF-κB/NLRP3 Signaling pathway and activating the Nrf2/HO-1 Signaling pathway to protect guinea pigs from lung injury caused by BoAHV-1. Importantly, this study provides a compelling argument for the GLY in combating respiratory disease in cattle caused by BoAHV-1.

Guo B ，Wang H ，Zhang Y ，Wang C ，Zhang H ，Zhao Y ，Qin J ... -  《-》

[Protective effect of tumor necrosis factor receptor-associated factor 6 inhibitor C25-140 on acute kidney injury induced by diquat poisoning in mice].

Huang T ，Rao G ，Zhao Z ，Xu N ，Zhou M ，Ou R ... -  《-》