Qinhuo Shanggan oral solution resolves acute lung injury by down-regulating TLR4/NF-κB signaling cascade and inhibiting NLRP3 inflammasome activation

Apium graveolens L. alleviates acute lung injury in human A-549 cells by reducing NF-κB and NLRP3 inflammasome signaling

BACKGROUND

Apium graveolens L. (celery) is a dietary vegetable with anti-inflammatory properties. It has the potential to treat acute lung injury (ALI) caused by COVID-19 or other diseases.

OBJECTIVE

To investigate the effects of Apium graveolens water extract (AGWE) on ALI in human lung A-549 cells induced by lipopolysaccharide (LPS).

MATERIALS AND METHODS

A-549 cells were treated with AGWE for 24 h and then stimulated with 10 μg/mL LPS for another 24 h. The effects of AGWE on cell viability, the inflammatory response, oxidative stress, and apoptosis and their regulatory factors, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and NLR family pyrin domain containing 3 (NLRP3) inflammasome signaling activation were analyzed.

RESULTS

Treatment with 5-50 μg/mL AGWE reversed the decrease in cell viability caused by LPS (p < 0.05). AGWE can reduce interleukin (IL)-1β, IL-6, IL-18, and TNF-α levels; their EC50 values are 61.4, 65.7, 37.8, and 79.7 μg/mL, respectively. AGWE can reduce reactive oxygen species and thiobarbituric acid reactive substances in A-549 cells induced by LPS. AGWE also reduced the levels of apoptosis (EC50 of 74.8 μg/mL) and its regulators (Bid; Caspase-9, -8, and -3; Bax) and increased the levels of the mitochondrial membrane potential in A-549 cells induced by LPS. AGWE can also decrease the protein levels of NLRP3 and Caspase-1 and the activation of NF-κB signaling in A-549 cells induced by LPS.

CONCLUSIONS

These results show that 10 and 50 μg/mL AGWE can reduce the acute inflammation induced by LPS by reducing NF-κB and NLRP3 inflammasome signaling and mitochondria-dependent apoptosis pathways.

TLR4-mediated endoplasmic reticulum stress regulates pyroptosis in macrophages infected with the Bacillus Calmette-Guérin mycobacterial

Tuberculosis results from Mycobacterium tuberculosis (Mtb) infection. Immune responses controlled by Toll-like receptor 4 (TLR4) are closely associated with the host response to pathogens, including Mtb. NLRP3 inflammasome-mediated pyroptosis forms a significant part of the inflammatory response during Mtb infection, and endoplasmic reticulum stress (ERS) is implicated in the activation of the NLRP3 inflammasome. Here, the function of TLR4 in macrophage pyroptosis induced by infection with the Bacillus Calmette-Guérin (BCG) mycobacterial strain was investigated. It was found that infection with BCG activated TLR4 signaling, induced ERS and subsequent NLRP3 inflammasome activation, leading to pyroptosis in mouse lung tissues. The TLR4 inhibitor TAK 242 inhibited the ERS onset, NLRP3 inflammasome stimulation, and pyroptosis, while the ERS inhibitor TUDCA blocked both inflammasome activation and pyroptosis, and the NLRP3 inhibitor MCC950 specifically inhibited pyroptosis. Furthermore, TAK 242, TUDCA, and MCC950 all exacerbated lung injury caused by BCG infection and promoted BCG survival. Similarly, after in BCG-infected THP-1 macrophages, TLR4 signaling was found to mediate NLRP3 inflammasome activation through ERS, thereby inducing pyroptosis. In summary, BCG infection leads to macrophage pyroptosis via the TLR4/ERS/NLRP3 inflammasome signaling axis, providing new insights for further research into the pathogenesis and treatment of tuberculosis.

Kurarinone Attenuates LPS-Induced Pneumonia by Inhibiting MAPK and NF-κB Signaling Pathways

Kurarinone is a prenylated flavanone isolated from Sophora flavescens Aiton. This investigation aimed to elucidate whether kurarinone could ameliorate lipopolysaccharide (LPS)-induced pneumonia and explore the underlying mechanism. C57BL/6 mice were treated with LPS (50 μg/20 μL) to establish pneumonia models. Kurarinone (100 mg/kg) or dexamethasone (DEX, 5 mg/kg) was administered for 7 days before LPS inhalation. BEAS-2B cells were incubated with kurarinone at 1, 2, and 5 μM for 2 h before LPS stimulation for 24 h. We found that kurarinone ameliorated lung injury and inflammatory cell infiltration in the mouse lung (p < 0.001). Kurarinone decreased MPO activity (47.6%, p < 0.001) and alleviated the inflammatory response by reducing the levels of IL-1β (34.9%, p < 0.001), TNF-α (55.1%, p < 0.001), and IL-6 (36.2%, p < 0.001) in the lung. Kurarinone reduced the levels of IL-1β, TNF-α, IL-6, iNOS, and COX2 in LPS-treated BEAS-2B cells in a concentration-dependent manner (p < 0.05). Mechanistically, kurarinone restrained LPS-induced activation of MAPK and NF-κB pathways in vivo and in vitro (p < 0.05). Overall, kurarinone alleviates LPS-induced pneumonia in mice by reducing inflammation via MAPK and NF-κB pathways, suggesting that kurarinone might be a potential therapeutic agent for pneumonia. This study provides new research ideas for the discovery of natural flavonoids that can treat pneumonia.

Total flavonoids from the aerial parts of Tetrastigma hemsleyanum prevent LPS-induced ALI by modulating the TLR4/NF-κB pathway in mice

BACKGROUND

The traditional Chinese medicine Tetrastigma Hemsleyanum (TH) is employed in treating respiratory diseases; however, the aerial parts by which its total flavonoids alleviate acute lung injury (ALI) are still unknown. This study investigated the protective effect and mechanism of Tetrastigma Hemsleyanum flavonoids (THF) in lipopolysaccharide (LPS)-induced ALI in mice.

METHODS

Firstly, the total flavonoids from the above-ground part of TH were extracted. Subsequently, the composition of THF was analyzed using LC-MS. In vivo, the impact of THF on ALI mice was assessed through lung histopathology and the evaluation of various inflammatory factors' expression in mice. After treating RAW264.7 cells with THF in vitro, changes in inflammatory markers were examined upon LPS stimulation, and mRNA expression levels of inflammatory factors were detected using RT-qPCR. Finally, Western blot analysis was performed to determine TLR4/NF-κB pathway-associated proteins expression.

RESULTS

In summary, a total of 24 flavonoids have been identified in THF. In vivo and vitro results show that THF effectively reduces the damage caused by LPS inflammation by blocking the expression and release of inflammatory factors. THF alleviates inflammatory injury by modulating the TLR4/NF-KB pathway.

CONCLUSION

The results suggest that flavonoids exhibit a potent anti-inflammatory effect and effectively mitigate LPS-induced injury both in vivo and in vitro. We suggested that these flavonoids exert their therapeutic effects by modulating the TLR4/NF-KB pathway. In conclusion, the development of THF is anticipated to represent a promising new pharmaceutical for treatingALI.

Interplay of TLR4 and SARS-CoV-2: Unveiling the Complex Mechanisms of Inflammation and Severity in COVID-19 Infections

The late 2019 emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, caused profound and unprecedented disruption to the global socio-economic structure, negatively affecting millions of lives worldwide. A typical hallmark of severe COVID-19 is hyper inflammation due to aberrant cytokine release (cytokine storm) by innate immune cells. Recent studies have revealed that SARS-CoV-2, through its spike (S) protein, can activate the body's innate immune cells via Toll-Like Receptors (TLRs), particularly TLR4. In silico studies have demonstrated that the S protein binds with high affinity to TLR4, triggering downstream signaling processes that result in pro-inflammatory cytokine release. Compared to other TLRs, such as TLR2, TLR4 plays a more significant role in initiating and sustaining the inflammatory response associated with severe COVID-19. Furthermore, interactions between the virus and target cells can enhance the cellular expression of TLR4, making cells more susceptible to viral interactions and subsequent inflammation. This increased expression of TLR4 upon viral entry creates a feedback loop, where heightened TLR4 levels lead to amplified inflammatory responses, contributing to the severity of the disease. Additionally, TLR4's potent activation of inflammatory pathways sets it apart from other TLRs, underscoring its pivotal role in the pathogenesis of COVID-19. In this review, we thoroughly explore the multitude of regulatory signaling pathways that SARS-CoV-2 employs to incite inflammation. We specifically focus on the critical impact of TLR4 activation compared to other TLRs, highlighting how TLR4's interactions with the viral S protein can exacerbate the severity of COVID-19. By delving into the mechanisms of TLR4-mediated inflammation, we aim to shed light on potential therapeutic targets that could mitigate the inflammatory damage caused by severe COVID-19. Understanding the unique role of TLR4 in the context of SARS-CoV-2 infection could pave the way for novel treatment strategies that specifically inhibit this receptor's activity, thereby reducing the overall disease burden and improving patient outcomes.

Armeniacae semen amarum: a review on its botany, phytochemistry, pharmacology, clinical application, toxicology and pharmacokinetics

Armeniacae semen amarum-seeds of Prunus armeniaca L. (Rosaceae) (ASA), also known as Kuxingren in Chinese, is a traditional Chinese herbal drug commonly used for lung disease and intestinal disorders. It has long been used to treat coughs and asthma, as well as to lubricate the colon and reduce constipation. ASA refers to the dried ripe seed of diverse species of Rosaceae and contains a variety of phytochemical components, including glycosides, organic acids, amino acids, flavonoids, terpenes, phytosterols, phenylpropanoids, and other components. Extensive data shows that ASA exhibits various pharmacological activities, such as anticancer activity, anti-oxidation, antimicrobial activity, anti-inflammation, protection of cardiovascular, neural, respiratory and digestive systems, antidiabetic effects, and protection of the liver and kidney, and other activities. In clinical practice, ASA can be used as a single drug or in combination with other traditional Chinese medicines, forming ASA-containing formulas, to treat various afflictions. However, it is important to consider the potential adverse reactions and pharmacokinetic properties of ASA during its clinical use. Overall, with various bioactive components, diversified pharmacological actions and potent efficacies, ASA is a promising drug that merits in-depth study on its functional mechanisms to facilitate its clinical application.