Differential regulation of MyD88- and TRIF-dependent signaling pathways of Toll-like receptors by cardamonin

Unveiling the multifaceted role of toll-like receptors in immunity of aquatic animals: pioneering strategies for disease management

The pattern recognition receptor (PRR), which drives innate immunity, shields the host against invasive pathogens. Fish and other aquatic species with poorly developed adaptive immunity mostly rely on their innate immunity, regulated by PRRs such as inherited-encoded toll-like receptors (TLRs). The discovery of 21 unique TLR variations in various aquatic animals over the past several years has sparked interest in using TLRs to improve aquatic animal's immune response and disease resistance. This comprehensive review provides an overview of the latest investigations on the various characteristics of TLRs in aquatic animals. It emphasizes their categorization, insights into 3D architecture, ligand recognition, signaling pathways, TLRs mediated immune responses under biotic and abiotic stressors, and expression variations during several developmental stages. It also highlights the differences among aquatic animals' TLRs and their mammal counterparts, which signifies the unique roles that TLRs play in aquatic animal's immune systems. This article summarizes current aquaculture research to enhance our understanding of fish immune systems for effective aquaculture -related disease management.

Characteristic chromanone acids from Calophyllum membranaceum: Determination of C-3 configuration and anti-inflammatory activity

One undescribed homologous furanochromanone (1) featuring a 6/6/5/3 tetracyclic skeleton and four highly oxidized pyranochromanones (2-5), along with a set of four pyranochromanone stereoisomers [(±)-6a and (±)-6b], were isolated from the leaves of Calophyllum membranaceum Gardn. Et Champ. Their structures were elucidated by using spectroscopic data, Snatzke's method, quantum-chemical calculations, and X-ray crystallographic analysis. The correlation of characteristic Cotton effects and specific chemical shifts with C-3 configuration provided a convenient approach to assign the C-3 configuration of 2,3-dimethylchromanones. The stereochemical assignments of 3-OH substituted pyranochromanones by quantum-based NMR methods following single/double MTPA derivatization were consistent with the ECD/NMR prediction, which verified the feasibility and reliability of the proposed empirical rule. The underlying mechanism was further clarified by conformational and molecular orbital analyses. Moreover, biological evaluation and binding assays demonstrated that compound 3 (KD = 0.45 μM) tightly binds to the TLR4-MD2 target, thereby inhibiting the TLR4/MyD88-dependent and -independent signal pathways. This study provides the first evidence that Calophyllum chromanones are a novel structural type of TLR4 inhibitors, exerting their anti-inflammatory effects by disrupting the binding between TLR4 and MD2.

Ginsenoside Rg1 attenuates cerebral ischemia-reperfusion injury through inhibiting the inflammatory activation of microglia

It is recognized that the cerebral ischemia/reperfusion (I/R) injury triggers inflammatory activation of microglia and supports microglia-driven neuronal damage. Our previous studies have shown that ginsenoside Rg1 had a significant protective effect on focal cerebral I/R injury in middle cerebral artery occlusion (MCAO) rats. However, the mechanism still needs further clarification. Here, we firstly reported that ginsenoside Rg1 effectively suppressed the inflammatory activation of brain microglia cells under I/R conditions depending on the inhibition of Toll-likereceptor4 (TLR4) proteins. In vivo experiments showed that the ginsenoside Rg1 administration could significantly improve the cognitive function of MCAO rats, and in vitro experimental data showed that ginsenoside Rg1 significantly alleviated neuronal damage via inhibiting the inflammatory response in microglia cells co-cultured under oxygen and glucose deprivation/reoxygenation (OGD/R) condition in gradient dependent. The mechanism study showed that the effect of ginsenoside Rg1 depends on the suppression of TLR4/MyD88/NF-κB and TLR4/TRIF/IRF-3 pathways in microglia cells. In a word, our research shows that ginsenoside Rg1 has great application potential in attenuating the cerebral I/R injury by targeting TLR4 protein in the microglia cells.

Toll-Like Receptor Signaling in Severe Acute Respiratory Syndrome Coronavirus 2-Induced Innate Immune Responses and the Potential Application Value of Toll-Like Receptor Immunomodulators in Patients With Coronavirus Disease 2019

Toll-like receptors (TLRs) are key sensors that recognize the pathogen-associated molecular patterns (PAMPs) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to activate innate immune response to clear the invading virus. However, dysregulated immune responses may elicit the overproduction of proinflammatory cytokines and chemokines, resulting in the enhancement of immune-mediated pathology. Therefore, a proper understanding of the interaction between SARS-CoV-2 and TLR-induced immune responses is very important for the development of effective preventive and therapeutic strategies. In this review, we discuss the recognition of SARS-CoV-2 components by TLRs and the downstream signaling pathways that are activated, as well as the dual role of TLRs in regulating antiviral effects and excessive inflammatory responses in patients with coronavirus disease 2019 (COVID-19). In addition, this article describes recent progress in the development of TLR immunomodulators including the agonists and antagonists, as vaccine adjuvants or agents used to treat hyperinflammatory responses during SARS-CoV-2 infection.

Protection of Toll-Like Receptor 9 Against Lipopolysaccharide-Induced Inflammation and Oxidative Stress of Pulmonary Epithelial Cells via MyD88-Mediated Pathways

Acute lung injury (ALI) caused by lipopolysaccharide (LPS) is a common, severe clinical syndrome. Injury caused by inflammation and oxidative stress in vascular endothelial and alveolar epithelial cells is a vital process in the pathogenesis of ALI. Toll-like receptor 9 (TLR9) is highly expressed in LPS-induced ALI rats. In this study, Beas-2B human pulmonary epithelial cells and A549 alveolar epithelial cells were stimulated by LPS, resulting in the upregulation of TLR9 in a concentration-dependent manner. Furthermore, TLR9 overexpression and interference vectors were transfected before LPS administration to explore the role of TLR9 in LPS-induced ALI in vitro. The findings revealed that inhibition of TLR9 reduced inflammation and oxidative stress while suppressing apoptosis of LPS-induced Beas-2B and A549 cells, whereas TLR9 overexpression aggravated these conditions. Moreover, TLR9 inhibition resulted in downregulated protein expression of myeloid differentiation protein 88 (MyD88) and activator activator protein 1 (AP-1), as well as phosphorylation of nuclear factor-B (NF-B), c-Jun N terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK). The phosphorylation of extracellular-regulated protein kinases 1/2 was upregulated compared to that of cells subjected to only LPS administration, and this was reversed by TLR9 overexpression. These results indicate that inhibition of TLR9 plays a protective role against LPS-induced inflammation and oxidative stress in Beas-2B and A549 cells, possibly via the MyD88/NF-B and MyD88/MAPKs/AP-1 pathways.

Recent development on COX-2 inhibitors as promising anti-inflammatory agents: The past 10 years

Cyclooxygenases play a vital role in inflammation and are responsible for the production of prostaglandins. Two cyclooxygenases are described, the constitutive cyclooxygenase-1 and the inducible cyclooxygenase-2, for which the target inhibitors are the non-steroidal anti-inflammatory drugs (NSAIDs). Prostaglandins are a class of lipid compounds that mediate acute and chronic inflammation. NSAIDs are the most frequent choices for treatment of inflammation. Nevertheless, currently used anti-inflammatory drugs have become associated with a variety of adverse effects which lead to diminished output even market withdrawal. Recently, more studies have been carried out on searching novel selective COX-2 inhibitors with safety profiles. In this review, we highlight the various structural classes of organic and natural scaffolds with efficient COX-2 inhibitory activity reported during 2011–2021. It will be valuable for pharmaceutical scientists to read up on the current chemicals to pave the way for subsequent research.

Tob2 Inhibits TLR-Induced Inflammatory Responses by Association with TRAF6 and MyD88

Optimal activation of TLR pathways is crucial for the initiation of inflammatory responses and eliminating invading micro-organisms. However, excessive of TLR activation may lead to autoimmune and inflammatory diseases. Thus, TLR pathways should be tightly controlled. In this study, we identify Tob2, a Tob/BTG family member, as a suppressor of TLR pathways. Tob2 deficiency enhances TLR-induced NF-κB and MAPK activation and promotes the expression of proinflammatory cytokines in primary peritoneal macrophages of C57BL/6 mice. Furthermore, Tob2-defective C57BL/6 mice may be more susceptible to endotoxemic shock in vivo. Mechanistically, Tob2 interacts with TRAF6 and MyD88 and thus inhibits signaling from the MyD88-TRAF6 complex in primary peritoneal macrophages and HEK293T cells. Therefore, our results uncover a regulatory mechanism of TLR pathways and provide a potential target for the intervention of diseases with excessive TLR activation.

Cardamonin: A new player to fight cancer via multiple cancer signaling pathways

Nature's pharmacy has undoubtedly served humans as an affordable and safer health-care regime for a long times. Cardamonin, a chalconoid present in several plants has been known for a longtime to have beneficial properties towards human health. In this review, we aimed to highlight the recent advances achieved in discovering the pharmacological properties of cardamonin. Cardamonin is cardamom-derived chalcone, which plays a role in cancer treatment, immune system modulation, inflammation and pathogens killing. Through the modulation of cellular signaling pathways, cardamonin activates cell death signal to induce apoptosis in malignant cells that results in the inhibition of cancer development. Moreover, cardamonin arrests cell cycle by altering the expression of regulatory proteins during malignant cells division. Due to its relatively selective cytotoxic potential against host malignant cells, cardamonin is emerging as a promising novel experimental anticancer agent. The potential of cardamonin to target various signaling molecules, transcriptional factors, cytokines and enzymes, such as mTOR, NF-κB, Akt, STAT3, Wnt/β-catenin and COX-2 enhances the opportunity to explore it as a new multi-target therapeutic agent. The pharmacokinetic and biosafety profile of cardamonin favor it as a potentially safe biomolecule for pharmaceutical drug development.

Study on Schizochytrium sp. improving the growth performance and non-specific immunity of golden pompano (Trachinotus ovatus) while not affecting the antioxidant capacity

A feeding experiment was conducted to determine the effects of Schizochytrium sp. on growth performance, antioxidant capacity and non-specific immunity in golden pompano (Trachinotus ovatus).Two diets were formulated with or without Schizochytrium sp. supplemented (D1:0% and D2: 3%) to feed fish for 8 weeks. Results showed that growth performance, feed intake and survival rate increased significantly with Schizochytrium sp. supplemented (P < 0.05). Feed coefficient rate (FCR) of golden pompano fed the diet supplemented with Schizochytrium sp. was significantly lower than that of fish fed the control diet (P < 0.05). No significant differences were found in antioxidant capacity both in transcriptional level, including nclear factor erythroid-2-related factor-2 (Nrf2), Kelch-like-ECH-associated protein (keap1), catalase (CAT), glutathione peroxidase (GSH-PX) and heme oxygenase 1 (HO-1) and enzyme activity, such as total antioxidant capacity (T-AOC), malondialdehyde (MDA) and superoxide dismutase (SOD) (P > 0.05). Gut amylase and lipase were significantly higher in dietary Schizochytrium sp. supplemented treatment than that in control group (P < 0.05). The relative peroxisome proliferator-activated receptor-α (PPARα) expression level in liver was significantly higher in Schizochytrium sp supplemented treatment than that in control one (P < 0.05). The mRNA expression of myeloid differentiation factor 88 (MyD88), IL-1R-associated kinases 4 (IRAK4), interferon regulating Factor 3 (IRF3), interferon regulating Factor 3(IRF7) and heat shock protein 70 (HSP70) were significantly lower in Schizochytrium sp. supplemented treatment than that in control one (P < 0.05). In Schizochytrium sp. supplemented diet, golden pompano had significantly longer villi length than that in control diet (P < 0.05); muscle thickness in Schizochytrium sp. supplemented diet was thicker than that in control one (P < 0.05) and there were more goblet cells in Schizochytrium sp. treatment (P < 0.05). After the rearing trial, an air exposure trial was conducted. Results showed that the air-exposure mortality (AEM) and mRNA expression level of Nrf2, keap1, CAT, GSH-PX and HO-1 showed no significant difference (P > 0.05). These results indicated that dietary Schizochytrium sp. improved the growth performance and non-specific immunity of golden pompano while made no difference to antioxidant capacity.

Cardamonin exerts anti-gastric cancer activity via inhibiting LncRNA-PVT1-STAT3 axis

Background: Gastric cancer is one of the most commonly diagnosed cancers each year, and it remains the third leading cause of cancer death in the world. The clinicopathologic characteristics differ among regions, so epigenetic changes play a key role in gastric carcinogenesis. Methods: In the present study, we first demonstrate that cardamonin, a natural production of chalcone, is an anti-gastric cancer agent in pre-clinical evaluation. Results: Cardamonin inhibited proliferation and migration, induced apoptosis in gastric cancer cells. It could reduce the expression of apoptosis-related and migration-related genes and proteins. The constant activation of STAT3 (signal transducer and activator of transcription 3) signal is a major intrinsic signal for cancer inflammation. It regulates cellular proliferation, cell cycle, and migration that are critical for cancer procession. Cardamonin could effectively down-regulate p-STAT3 and abolish activation of STAT3 through inhibiting the expression of LncRNA-PVT1. Conclusion: The present study revealed that cardamonin is a potential natural source of anti-gastric cancer drugs via epigenetic mechanism to inhibit LncRNA-PVT1-STAT3 axis.

Xiao Qing Long Tang essential oil exhibits inhibitory effects on the release of pro-inflammatory mediators by suppressing NF-κB, AP-1, and IRF3 signalling in the lipopolysaccharide-stimulated RAW264.7 cells

Xiao Qing Long Tang (literally “Minor blue dragon decoction” in Chinese), a traditional Chinese formula, is prescribed to treat respiratory diseases. However, only few studies have been reported on its anti-inflammatory mechanisms. In this study, we investigated the inhibitory effects of Xiao Qing Long Tang essential oil on inflammatory mediators and explored the mechanisms of action of XQEO in the lipopolysaccharide (LPS)-stimulated RAW264.7 cells. XQEO was prepared via steam distillation and characterized by GC-MS analysis. MTT and Griess assays were used to measure cell viability and NO production, respectively. The mRNA expression and the production of LPS-induced pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-10) and chemokines (MCP-1, Rantes, and MIP-1α) were determined by real-time PCR and enzyme-linked immunosorbent assay, respectively. Furthermore, we determined the protein levels of the components of NF-κB, AP-1 and IRF3 signalling by Western blotting. Immunofluorescence assay was used to estimate the nuclear translocation of NF-κB, AP-1 and IRF3. The results showed that XQEO inhibited the secretion of NO and PGE2 and down-regulated the mRNA and protein levels of iNOS and COX-2. We also found that XQEO suppressed the LPS-induced overproduction of pro-inflammatory mediators. Moreover, XQEO inhibited the phosphorylation of NF-κB/p65, AP-1/c-Jun, and IRF3 by suppressing their upstream kinases, such as MAPKs, TBK1, Akt, IKKα/β, and IκB, reducing the LPS-induced NF-κB, AP-1 and IRF3 translocation to the nucleus. These findings suggest that XQEO effectively suppresses the production of pro-inflammatory mediators possibly through the inhibition of NF-κB, AP-1, and IRF3 signalling in the LPS-stimulated RAW264.7 cells.

Xiao Qing Long Tang essential oil suppresses the production of inflammatory mediators via blocking NF-κB, AP-1, and IRF3 signalling in the lipopolysaccharide-stimulated RAW264.7 cells.

Re-Du-Ning inhalation solution exerts suppressive effect on the secretion of inflammatory mediators via inhibiting IKKα/β/IκBα/NF-κB, MAPKs/AP-1, and TBK1/IRF3 signaling pathways in lipopolysaccharide stimulated RAW 264.7 macrophages

Background: Re-Du-Ning inhalation solution (RIS) is a novel preparation derived from the Re-Du-Ning injection, which has been clinically used to treat respiratory diseases such as pneumonia for more than twenty years in China. However, scant reports have been issued on its anti-inflammatory mechanisms. Aim: we investigated the suppressive effect of RIS on inflammatory mediators and explored the underlying mechanism of action. Methods: RIS freeze dried powder was characterized by HPLC analysis. Lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage was selected as the cell model. The cell viability was determined by using the MTT assay. Moreover, the production of nitric oxide (NO) was measured by the Griess reaction. The protein secretions from inflammatory mediators were determined by the enzyme-linked immunosorbent assay (ELISA). The protein levels and enzyme activities were examined by Western blotting. The nuclear translocation of nuclear factor-kappa B (NF-κB), AP-1, and IRF3 was further explored by immunofluorescence assay. Results: the viability of the RAW 264.7 cells was not significantly changed after 24 h incubation with RIS concentration up to 400 μg mL-1. The RIS remarkably reduced the production of NO and prostaglandin E2 (PGE2), and downregulated the expression of iNOS and COX-2. The concentrations of cytokines (IL-1β, IL-6, and TNF-α) and chemokines (MCP-1, CCL-5, and MIP-1α) in the culture medium were significantly decreased by the RIS treatment. Furthermore, the phosphorylation of IκB-α, IKKα/β, TBK1, ERK, p38, JNK, NF-κB, AP-1, and IRF3 was downregulated by the RIS treatment. The nuclear translocation of NF-κB, AP-1, and IRF3 was also inhibited after the RIS treatment. Conclusion: the suppressive effect of RIS is associated with the regulated NF-κB, AP-1, and IRF3 and their upstream proteins. This study provides a pharmacological basis for the application of RIS in the treatment of inflammatory disorders.