Neuroprotection of chicoric acid in a mouse model of Parkinson's disease involves gut microbiota and TLR4 signaling pathway

Chicoric acid (CA), a polyphenolic acid obtained from chicory and purple coneflower (Echinacea purpurea), has been regarded as nutraceutical to combat inflammation, virus and obesity. Parkinson’s Disease (PD) is a...

Glucagon-Like Peptide-1 Agonist Exendin-4 Facilitates the Extinction of Cocaine-Induced Condition Place Preference

Accumulating studies suggest that the glucagon-like peptide-1 receptor agonist exendin-4 (Ex4) and toll-like receptor 4 (TLR4) play a pivotal role in the maladaptive behavior of cocaine. However, few studies have assessed whether Ex4 can facilitate the extinction of drug-associated behavior and attenuate the reinstatement of cocaine-induced condition place preference (CPP) in mice. The main objective of the present study was to evaluate Ex4’s ability to regulate the extinction and reinstatement of cocaine-induced CPP. C57BL/6 mice were conditioned to either cocaine (20 mg/kg) or an equivalent volume of saline to establish a cocaine-mediated CPP paradigm. To investigate the potential effects of Ex4 on extinction, animals received an intraperitoneal injection of Ex4 either immediately or 6 h after each extinction or only on the test day. The persistence of extinction was measured using the reinstatement paradigm evoked by 10 mg/kg of cocaine. To explore the possible impacts of Ex4 and neuroinflammation on cocaine, the expression levels of TLR4 within the hippocampus was detected using western blotting. As a result, we found that systemic administration of Ex4 immediately after each extinction training, instead of 6 h after each extinction and on the day of extinction test, was capable of facilitating extinction in the confined or non-confined CPP extinction paradigms and blocking the cocaine-primed reinstatement of cocaine-induced CPP. Additionally, we also observed that Ex4 was competent to alleviate TLR4 signaling that has been up-regulated by cocaine. Altogether, our findings indicated that the combination of Ex4 with daily extinction training was sufficient to facilitate extinction of the conditioned behavior, attenuate reinstatement of cocaine-induced CPP and inhibit TLR4 signaling. Thus, Ex4 deserves further investigation as a potential intervention for the treatment of cocaine use disorder.

Notch1 Signaling Contributed To TLR4-Triggered NF-kB Activation In Macrophages

Background: Macrophages substantially shape the development, progression, and complications of inflammation-driven diseases. Although numerous researches support a critical role for Notch signaling in most inflammatory diseases, there is limited data on the role of Notch signaling in TLR4-induced macrophage activation and the interaction of Notch signaling with other signaling pathways(e.g., the NF-kB pathway during inflammation) in macrophages. Methods and Results: In this study, we confirmed that stimulation with TLR4 ligand LPS up-regulates Notch1 expression in RAW264.7 monocyte/macrophage-like cell line. LPS also induced the expression of Notch target genes Notch1 and Hes1 mRNA in macrophages, suggesting that TLR4 signaling enhances Notch pathway activation. The upregulation of Notch1, NICD, and Hes1 protein by LPS treatment was inhibited by the Notch1 inhibitor of DAPT. The increase of TNF-a, IL-6, and IL-1b induced by LPS was inhibited by DAPT while jagged1, the Notch1 ligand, rescued them. Furthermore, the suppression of Notch signaling by DAPT up-regulated CYLD expression but down-regulated TRAF6, IKKa/bphosphorylation, and subsequently phosphorylation and degradation of IκB-α, indicating the inhibition of TLR4-triggered NF-kB activation by DAPT. Interestingly, DAPT showed no inhibitory effect on the increase of MyD88 expression induced by LPS in our study. Conclusions: Our study shows that the stimulation of macrophages via the TLR4 signaling cascade triggers the activation of Notch1 signaling, which regulates the expression patterns of genes involved in pro-inflammatory responses through by activating NF-kB. It may be dependent on the CYLD-TRAF6-IKK pathway. The Notch1 signaling may be considered as a potential therapeutic target against infectious and inflammatory driven diseases.

Fecal microbiota transplantation protects rotenone-induced Parkinson’s disease mice via suppressing inflammation mediated by the lipopolysaccharide-TLR4 signaling pathway through the microbiota-gut-brain axis

Background Parkinson’s disease (PD) is a prevalent neurodegenerative disorder, displaying not only well-known motor deficits but also gastrointestinal dysfunctions. Consistently, it has been increasingly evident that gut microbiota affects the communication between the gut and the brain in PD pathogenesis, known as the microbiota-gut-brain axis. As an approach to re-establishing a normal microbiota community, fecal microbiota transplantation (FMT) has exerted beneficial effects on PD in recent studies. Here, in this study, we established a chronic rotenone-induced PD mouse model to evaluate the protective effects of FMT treatment on PD and to explore the underlying mechanisms, which also proves the involvement of gut microbiota dysbiosis in PD pathogenesis via the microbiota-gut-brain axis. Results We demonstrated that gut microbiota dysbiosis induced by rotenone administration caused gastrointestinal function impairment and poor behavioral performances in the PD mice. Moreover, 16S RNA sequencing identified the increase of bacterial genera Akkermansia and Desulfovibrio in fecal samples of rotenone-induced mice. By contrast, FMT treatment remarkably restored the gut microbial community, thus ameliorating the gastrointestinal dysfunctions and the motor deficits of the PD mice. Further experiments revealed that FMT administration alleviated intestinal inflammation and barrier destruction, thus reducing the levels of systemic inflammation. Subsequently, FMT treatment attenuated blood-brain barrier (BBB) impairment and suppressed neuroinflammation in the substantia nigra (SN), which further decreased the damage of dopaminergic neurons. Additional mechanistic investigation discovered that FMT treatment reduced lipopolysaccharide (LPS) levels in the colon, the serum, and the SN, thereafter suppressing the TLR4/MyD88/NF-κB signaling pathway and its downstream pro-inflammatory products both in the SN and the colon. Conclusions Our current study demonstrates that FMT treatment can correct the gut microbiota dysbiosis and ameliorate the rotenone-induced PD mouse model, in which suppression of the inflammation mediated by the LPS-TLR4 signaling pathway both in the gut and the brain possibly plays a significant role. Further, we prove that rotenone-induced microbiota dysbiosis is involved in the genesis of PD via the microbiota-gut-brain axis.

319 The tumor-intrinsic NLRP3 inflammasome establishes a pulmonary metastatic niche via type II epithelial HSP70/TLR4 signaling and facilitates disease hyperprogression in response to immunotherapy

BackgroundOur understanding of those underlying mechanisms that contribute to metastatic progression in melanoma remains limited. While uncommon, melanoma hyperprogression in response to immunotherapy is likely to be an extreme form of acquired resistance. Therefore, studies that define the underlying mechanisms of these processes are expected to provide insight into the discovery of novel therapeutic targets and predictive biomarkers. We previously demonstrated that tumor-intrinsic NLRP3 drives adaptive resistance to anti-PD-1 immunotherapy (anti-PD-1) by inducing the recruitment of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) via the upregulation of CXCL5. Gain-of-function polymorphisms in the TLR4 gene have been associated with pulmonary metastases in melanoma patients. We have shown HSP70 to promote PMN-MDSC chemotaxis via the stimulation of TLR4 signaling. As a result, we hypothesized that the tumor NLRP3 inflammasome may also contribute to distant metastatic progression and disease hyperprogression during immunotherapy by establishing a long-distance signaling axis mediated by HSP70-TLR4 signaling in the lung.MethodsWe pharmacologically and genetically inhibited the NLRP3 inflammasome and HSP70 in a transgenic BRAFV600E mouse model to examine their role in distant metastatic progression before and during anti-PD-1. An inducible type II pulmonary epithelial cell-specific TLR4 knock-out mouse model was engineered to examine the role of distant HSP70-TLR4 signaling in the recruitment of PMN-MDSCs and subsequent metastatic progression to the lung. Plasma HSP70 levels were monitored in melanoma patients undergoing anti-PD-1ResultsAnti-PD-1 significantly increases CXCL2/CXCL5 expression and PMN-MDSC accumulation in the lungs of the transgenic BRAFV600E model. This effect is reversed by 1) tumor-targeted ablation and pharmacologic inhibition of NLRP3 but not systemic host knock-out of NLRP3, 2) Pharmacologic Wnt5a ligand inhibition, 3) tumor-specific ablation and inhibition of HSP70. Inducible knock-out of TLR4 in type II epithelial cells suppressed Wnt5a and CXCL5 expression and inhibited the recruitment of PMN-MDSCs to the lung in response to anti-PD-1. Tumor-specific inhibition of NLRP3/HSP70 and lung-specific ablation of TLR4 suppressed metastatic progression following anti-PD-1 in the BRAFV600E melanoma model. Combination anti-PD-1 and NLRP3 inhibition suppressed primary melanoma progression and distant melanoma metastases versus anti-PD-1 monotherapy. Elevated plasma levels of HSP70 were associated with disease hyperprogression in metastatic melanoma patients undergoing anti-PD-1Abstract 319 Figure 1Tumor-intrinsic NLRP3 inflammasome and metastasisConclusionsTogether, these results describe a novel cross-talk mechanism between the primary tumor and the lung that mediates distant metastatic progression that is accentuated following anti-PD-1 (figure 1). Future clinical studies are needed to evaluate the pharmacologic inhibition of this tumor-lung NLRP3/HSP70/TLR4/Wnt5a/CXCL5 axis on melanoma metastasis and disease hyperprogression during checkpoint inhibitor immunotherapy

Effect of Erdosteine on Middle Ear Effusion in Rats by Mediating TLR4 Signaling Pathway

The study aimed to investigate the effect of erdosteine on middle ear effusion in rats through mediating the Toll-like receptor 4 (TLR4) signaling pathway. Rats were injected with endotoxin to prepare the model of acute secretory otitis media (SOM). Then, they were divided into an acute SOM model group (model group, n = 15 ) and erdosteine treatment group (18 mg/kg, gavage, treatment group, n = 15 ). Besides, a normal group ( n = 15 ) was set up. Two weeks later, routine biochemical indicators such as aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were detected. The inflammatory effusion due to otitis media was scored. The content of myeloperoxidase (MPO), matrix metalloproteinase (MMP), and tumor necrosis factor-beta (TNF-β) in middle ear lavage fluid was detected via enzyme-linked immunosorbent assay (ELISA). Additionally, histomorphological changes were observed with the help of hematoxylin-eosin (HE) staining, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting assays were carried out to measure the expression levels of TLR4 pathway genes and proteins as well as the messenger ribonucleic acid (mRNA) expression levels of key factors for otitis media (mucin 2 (MUC2) and MUC5A). In the model group, the levels of AST, ALP, and glutamic-pyruvic transaminase (GPT) were significantly increased ( p < 0.05 ). Besides, the content of MPO, MMP, and TNF-β was overtly raised in the model group ( p < 0.05 ), while it was notably lowered in the treatment group ( p < 0.05 ). In the treatment group, the cilia were slightly swollen, and inflammatory cells were fewer. The mRNA levels of MUC2, MUC5A, and pathway genes TLR4 and c-Jun N-terminal kinase (JNK) were elevated in the model group. In addition, the protein assay results revealed that the protein levels of TLR4 and JNK were evidently increased in the model group. Erdosteine can treat the middle ear effusion in rats by repressing the activation of the TLR4 signaling pathway.

Standardized Extract of Asparagus officinalis Stem Attenuates SARS-CoV-2 Spike Protein-Induced IL-6 and IL-1β Production by Suppressing p44/42 MAPK and Akt Phosphorylation in Murine Primary Macrophages

Excessive host inflammation following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with severity and mortality in coronavirus disease 2019 (COVID-19). We recently reported that the SARS-CoV-2 spike protein S1 subunit (S1) induces pro-inflammatory responses by activating toll-like receptor 4 (TLR4) signaling in macrophages. A standardized extract of Asparagus officinalis stem (EAS) is a unique functional food that elicits anti-photoaging effects by suppressing pro-inflammatory signaling in hydrogen peroxide and ultraviolet B-exposed skin fibroblasts. To elucidate its potential in preventing excessive inflammation in COVID-19, we examined the effects of EAS on pro-inflammatory responses in S1-stimulated macrophages. Murine peritoneal exudate macrophages were co-treated with EAS and S1. Concentrations and mRNA levels of pro-inflammatory cytokines were assessed using enzyme-linked immunosorbent assay and reverse transcription and real-time polymerase chain reaction, respectively. Expression and phosphorylation levels of signaling proteins were analyzed using western blotting and fluorescence immunomicroscopy. EAS significantly attenuated S1-induced secretion of interleukin (IL)-6 in a concentration-dependent manner without reducing cell viability. EAS also markedly suppressed the S1-induced transcription of IL-6 and IL-1β. However, among the TLR4 signaling proteins, EAS did not affect the degradation of inhibitor κBα, nuclear translocation of nuclear factor-κB p65 subunit, and phosphorylation of c-Jun N-terminal kinase p54 subunit after S1 exposure. In contrast, EAS significantly suppressed S1-induced phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) and Akt. Attenuation of S1-induced transcription of IL-6 and IL-1β by the MAPK kinase inhibitor U0126 was greater than that by the Akt inhibitor perifosine, and the effects were potentiated by simultaneous treatment with both inhibitors. These results suggest that EAS attenuates S1-induced IL-6 and IL-1β production by suppressing p44/42 MAPK and Akt signaling in macrophages. Therefore, EAS may be beneficial in regulating excessive inflammation in patients with COVID-19.