ATP citrate lyase ablation hampers exocrine regeneration via TLR4/NF-kappaB signaling after acute pancreatitis in mice.

BACKGROUND: ATP citrate lyase (Acly) is widely expressed in many tissues, has been proved to be involved in the pathogenesis of many inflammatory diseases. So far, the importance of Acly in acute pancreatitis(AP) has not been clearly determined. The purpose of this study is to clarify whether Acly can evoke inflammatory cascades in the progression of AP and hamper the subsequent regeneration process of pancreas. METHODS: Experimental pancreatitis in mice with a specific deficiency of Acly in the pancreas and in control mice through repetitive cerulein injections in vivo. The pancreas pathological grading, cell proliferative potential and the formation of acinar-to-ductal metaplasia (ADM) were evaluated. The levels of inflammatory cytokines in plasma were qualified by enzyme-linked immuno sorbent assay (ELISA). Pancreatic malondialdehyde (MDA), superoxide dismutase (SOD) activity and reduced glutathione (GSH) contents were measured for oxidative stress. The infiltration of macrophages and neutrophils, the expression of Toll like receptor 4 (TLR4), tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and the activation of nuclear factor kappaB (NF-κB) and cleaved Caspase-3, were measured using immunostaining. The mRNA transcription levels of TLR4, TNF-α, and IL-1ß in pancreatic tissues were detected by quantitative real-time PCR as well. Additionally, inhibition of TLR4 signaling by TAK-242 in AP mice with a pancreas-specific deletion of Acly was conducted in vivo. RESULTS: The results demonstrated that the elimination of pancreatic Acly not only exacerbated the severity of pancreatitis in mice during the initial inflammatory phase, as evidenced by more severe pathological damage, but also impeded the healing process of the exocrine pancreas by enhancing the formation of ADM and decreasing the ability of acinar cells to proliferate. In addition, deficiency of Acly increased the circulating TNF-α, IL-1ß and IL-6, the infiltration of macrophages and neutrophils, agumented the activation of nuclear factor kappaB (NF-κB) p65, the expression of TLR4, TNF-α, IL-1ß and cleaved Caspase-3, and exacerbated excessive oxidative stress in the pancreas at specific time points of AP mice. However, TLR4 inhibition significantly attenuated the structural and functional damage of the pancreas induced by AP in mice with a pancreas-specific deletion of Acly, as indicated by improvement of the above indexes. CONCLUSIONS: The present study demonstrated that ablation of pancreatic Acly intensified inflammatory reaction and cell death, and dampened exocrine regeneration following AP, due to the positive regulation of TLR4/NF-κB signaling activation.

Modulation of chemotherapy-induced peripheral neuropathy by JZL195 through glia and the endocannabinoid system.

Chemotherapy-induced peripheral neuropathy (CIPN) used to treat cancer, is a significant side effect with a complex pathophysiology, and its mechanisms remain unclear. Recent research highlights neuroinflammation, which is modulated by the endocannabinoid system (ECS) and associated with glial activation, and the role of toll-like receptor 4 (TLR4) in CIPN. This study aimed to investigate the effects of JZL195, an inhibitor of fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), and explore the connection between cannabinoid receptors and TLR4 in glial cells. A CIPN animal model was developed using cisplatin-injected male C57BL/6 mice. Mechanical and cold allodynia were assessed through von Frey and acetone tests. Western blot analysis was used to examine the expression of catabolic enzymes, cannabinoid receptors, glial cells, and neuroinflammatory factors in the dorsal root ganglia (DRGs) and spinal cord. Immunohistochemistry was used to investigate the colocalization of cannabinoid receptors and TLR4 in glial cells. JZL195 alleviated pain by inhibiting FAAH/MAGL, modulating the ECS and neuroinflammatory factors, and suppressing glial cell activity. Additionally, cannabinoid receptors and TLR4 colocalized with astrocytes and microglia in the spinal cord. This study highlights the therapeutic potential of JZL195 in modulating the ECS and suggests a correlation between cannabinoid receptors and TLR4 in spinal glial cells, providing insight into alleviating pain and neuroinflammation in CIPN.

Immunostimulatory Effects of Gamisoyosan on Macrophages via TLR4-Mediated Signaling Pathways.

BACKGROUND: This study aimed to analyze the immunostimulatory activity of gamisoyosan (GSS) on the activation of macrophages in RAW 264.7 cells and its underlying mechanisms. METHODS: The effects of GSS on the secretion of nitric oxide (NO), immunomodulatory mediators, cytokines and mRNAs, and related proteins were assessed using the Griess assay, Western blotting, quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and H2DCFDA, respectively. The level of phagocytosis was determined by the neutral red method while the immune function of GSS was determined using adhesion and wound-healing assays. RESULTS: GSS-treated macrophages significantly increased the production of NO, immunomodulatory enzymes, cytokines, and intracellular reactive oxygen species without causing cytotoxicity. GSS effectively improved macrophage immune function by increasing their phagocytic level, adhesion function, and migration activity. Mechanistic studies via Western blotting revealed that GSS notably induced the activation of the Toll-like receptor (TLR) 4-mediated mitogen-activated protein kinase, nuclear factor-κB, and protein kinase B signaling pathways. CONCLUSIONS: Overall, our results indicated that GSS could activate macrophages through the secretion of immune-mediated transporters via TLR4-dependent signaling pathways. Thus, GSS has potential value as an immunity-enhancing agent.

Update on Biomarkers of Chronic Inflammatory Processes Underlying Diabetic Neuropathy.

There is an increasing prevalence of diabetes mellitus (DM), particularly type 2 DM (T2DM), and its associated complications. T2DM is linked to insulin resistance, chronic inflammation, and oxidative stress, which can lead to both macrovascular and microvascular complications, including peripheral diabetic neuropathy (PDN). Inflammatory processes play a key role in the development and progression of T2DM and its complications, with specific markers like C-reactive protein (CRP), interleukins (ILs), and tumor necrosis factor (TNF)-α being associated with increased risk. Other key inflammatory markers such as nuclear factor kappa B (NF-κB) are activated under hyperglycemic and oxidative stress conditions and contribute to the aggravation of PDN by regulating inflammatory gene expression and enhancing endothelial dysfunction. Other important roles in the inflammatory processes are played by Toll-like receptors (TLRs), caveolin 1 (CAV1), and monocyte chemoattractant protein 1 (MCP1). There is a relationship between vitamin D deficiency and PDN, highlighting the critical role of vitamin D in regulating inflammation and immune responses. The involvement of macrophages in PDN is also suspected, emphasizing their role in chronic inflammation and nerve damage in diabetic patients. Vitamin D supplementation has been found to reduce neuropathy severity, decrease inflammatory markers, and improve glycemic control. These findings suggest that addressing vitamin D deficiency could offer therapeutic benefits for PDN. These molecular pathways are critical in understanding the pathogenesis of DM complications and may offer potential biomarkers or therapeutic targets including anti-inflammatory treatments, vitamin D supplementation, macrophage phenotype modulation, and lifestyle modifications, aimed at reducing inflammation and preventing PDN. Ongoing and more extensive clinical trials with the aim of investigating anti-inflammatory agents, TNF-α inhibitors, and antioxidants are needed to advance deeper into the understanding and treatment of painful diabetic neuropathy.

Mechanism research of Tollip negative feedback regulation in TLR4 signaling pathways based on spinal tuberculosis: Detection of Tollip and NF-κB expression levels.

The emergence of drug-resistant mycobacterium tuberculosis (MTB, or TB) strains has led to an increasing incidence of TB. Spinal tuberculosis is the most common extrapulmonary tuberculosis. In the present study, tollip, a negative feedback regulatory factor in TLR4 signaling pathway was chosen based on previous studies on osteoarticular tuberculosis. U937 cells were transfected with recombinant lentivirus containing shRNA (RNA interference, RNAi) or overexpression vector containing Tollip gene and tested in vitro. The expression levels of Tollip and TLR4 were detected by Real-time PCR and immunofluorescence techniques, and the cell morphology and infection effect were observed by DAPI staining. The results suggested that Tollip gene could negatively inhibit the expression of related factors in TLR4 signaling pathway, and thus is a potential biomarker for early diagnosis.

[Mechanism of analgesic effect of electroacupuncture on rats with cervical spondylosis radiculopathy based on activation of astrocytes and HMGB1/TLR4/MyD88 signaling pathway]. / 基于星形胶质细胞活化与HMGB1/TLR4/MyD88ä¿¡å·é€šè·¯æŽ¢è®¨ç”µé’ˆå¯¹ç¥žç»æ ¹åž‹é¢ˆæ¤Žç— å¤§é¼ çš„é•‡ç—›æœºåˆ¶.

OBJECTIVES: To observe effects of electroacupuncture (EA) on the activation of astrocytes and high mobility group protein B1(HMGB1)/Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling pathway, as well as related cytokines in rats with cervical spondylosis radiculopathy(CSR), so as to explore the analgesic mechanism of EA in treating CSR. METHODS: Twenty-four male SD rats were randomly divided into blank, sham surgery, model, and EA groups, with 6 rats in each group. CSR rat model was established by using cervical spinal cord canal puncture method. On the 7th day after successful modeling, EA was applied to rats in the EA group at bilateral "Hegu"(LI4) and "Taichong"(LR3) for 20 minutes(1.5 Hz, 1 mA), once daily for 7 consecutive days. Before and after intervention, gait impairment scores and mechanical pain thresholds were assessed. HE staining was used to observe pathological changes in spinal cord tissue. Western blot was used to detect the expression of HMGB1, TLR4, MyD88, and glial fibrillary acidic protein (GFAP) in the spinal cord. ELISA was used to measure the contents of CXC chemokine ligand 1 (CXCL1), chemokine ligand 2 (CCL2), tumor necrosis factor (TNF)-α, and interleukin (IL)-1ß in spinal cord. Immunofluorescence staining was used to observe GFAP protein positive expression in spinal cord tissue. RESULTS: There was no significant difference of all indexes between the blank group and the sham surgery group. Compared with the sham surgery group, mechanical pain threshold of rats in the model group was decreased(P<0.01), while gait impairment score, the contents of CXCL1, CCL2, TNF-α, IL-1ß, protein expressions of HMGB1, TLR4, MyD88 and GFAP, and positive expression of GFAP in spinal cord tissue were increased (P<0.01)；HE staining indicated severe overall morphological damage in the spinal cord of rats in the model group, with significant shrinkage of gray matter neurons, reduced number of Nissl bodies, and increased inflammatory cell infiltration. Compared with the model group, mechanical pain threshold in the EA group was increased (P<0.01), while gait impairment score, the contents of CXCL1, CCL2, TNF-α, IL-1ß, protein expressions of HMGB1, TLR4, MyD88 and GFAP, and positive expression of GFAP in spinal cord were reduced (P<0.01)；HE staining showed more intact neuronal cell bodies, increased number of Nissl bodies, and reduced shrinkage of gray matter neurons, inflammatory cell infiltration, and microvascular dilation in the spinal cord of rats in the EA group. CONCLUSIONS: EA can effectively alleviate pain in CSR rats, which is possibly by inhibiting astrocyte activation, HMGB1/TLR4/MyD88 signaling pathway, and reducing the release of related inflammatory cytokines, thus alleviating central sensitization in spinal segments.

Anti-Inflammatory Potential of Costus speciosus rhizome Bioactive Phytochemicals: A Combined GC-MS and Computational Approach Targeting TLR-4 Signaling.

BACKGROUND: Plants represent a rich reservoir of bioactive compounds with established therapeutic value in diverse diseases. Notably, the Toll-like receptor-4 (TLR-4) signaling pathway plays a pivotal role in inflammation. Upon engagement with pro-inflammatory ligands like lipopolysaccharide, TLR-4 triggers downstream cascades involving nuclear factor ĸappa B and mitogen- activated protein kinases. This signaling cascade ultimately dictates the onset and progression of inflammatory diseases. Therefore, targeting TLR-4 signaling offers a promising therapeutic approach for managing inflammatory disorders. METHODS: This study investigated the potential of Costus speciosus rhizome phytocompounds, a traditional medicinal plant, as novel as modulators of TLR-4 signaling, highlighting their mechanisms of action and potential clinical applications. In the present study, 18 phytocompounds isolated from the rhizome of Costus speciosus, were studied against TLR-4/AP-1 signaling, which is implicated in the inflammatory process using a computational approach. RESULTS: The compounds exhibited binding affinities ranging from -4.087 to -8.93 kcal/mol with the TLR-4 protein due to the formation of multiple intermolecular interactions. Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, methyl ester (compound 7) exhibited exceptional binding energy (-8.93 kcal/mol), indicating strong affinity for the TLR-4 protein. Additionally, compound 7 displayed favorable ADMET properties, suggesting promising drug development potential. Molecular dynamics simulations confirmed the stability of the compound 7-TLR4 complex, further supporting its ability to modulate TLR-4 signaling. CONCLUSION: These findings highlight the therapeutic potential of Costus speciosus phytocompounds, particularly compound 7, as potent anti-inflammatory modulators. Further research is warranted to validate their anti-inflammatory and neuroprotective effects in pre-clinical models, paving the way for their development as novel therapeutic agents for inflammatory diseases.

Investigate the binding of pesticides with the TLR4 receptor protein found in mammals and zebrafish using molecular docking and molecular dynamics simulations.

The widespread use of pesticides poses significant threats to both environmental and human health, primarily due to their potential toxic effects. The study investigated the cardiovascular toxicity of selected pesticides, focusing on their interactions with Toll-like receptor 4 (TLR4), an important part of the innate immune system. Using computational tools such as molecular docking, molecular dynamics (MD) simulations, principal component analysis (PCA), density functional theory (DFT) calculations, and ADME analysis, this study identified C160 as having the lowest binding affinity (-8.2 kcal/mol), followed by C107 and C165 (-8.0 kcal/mol). RMSD, RMSF, Rg, and hydrogen bond metrics indicated the formation of stable complexes between specific pesticides and TLR4. PCA revealed significant structural changes upon ligand binding, affecting stability and flexibility, while DFT calculations provided information about the stability, reactivity, and polarity of the compounds. ADME studies highlighted the solubility, permeability, and metabolic stability of C107, C160, and C165, suggesting their potential for bioavailability and impact on cardiovascular toxicity. C107 and C165 exhibit higher bioactivity scores, indicating favourable absorption, metabolism, and distribution properties. C165 also violated rule where molecular weight is greater than 500 g/mol. Further, DFT and NCI analysis of post MD conformations confirmed the binding of ligands at the binding pocket. The analysis shed light on the molecular mechanisms of pesticide-induced cardiovascular toxicity, aiding in the development of strategies to mitigate their harmful effects on human health.

Targeting TLR4 and regulating the Keap1/Nrf2 pathway with andrographolide to suppress inflammation and ferroptosis in LPS-induced acute lung injury.

Acute lung injury (ALI) is a severe inflammatory condition with a high mortality rate, often precipitated by sepsis. The pathophysiology of ALI involves complex mechanisms, including inflammation, oxidative stress, and ferroptosis, a novel form of regulated cell death. This study explores the therapeutic potential of andrographolide (AG), a bioactive compound derived from Andrographis, in mitigating Lipopolysaccharide (LPS)-induced inflammation and ferroptosis. Our research employed in vitro experiments with RAW264.7 macrophage cells and in vivo studies using a murine model of LPS-induced ALI. The results indicate that AG significantly suppresses the production of pro-inflammatory cytokines and inhibits ferroptosis in LPS-stimulated RAW264.7 cells. In vivo, AG treatment markedly reduces lung edema, decreases inflammatory cell infiltration, and mitigates ferroptosis in lung tissues of LPS-induced ALI mice. These protective effects are mediated via the modulation of the Toll-like receptor 4 (TLR4)/Kelch-like ECH-associated protein 1(Keap1)/Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. Molecular docking simulations identified the binding sites of AG on the TLR4 protein (Kd value: -33.5 kcal·mol-1), and these interactions were further corroborated by Cellular Thermal Shift Assay (CETSA) and SPR assays. Collectively, our findings demonstrate that AG exerts potent anti-inflammatory and anti-ferroptosis effects in LPS-induced ALI by targeting TLR4 and modulating the Keap1/Nrf2 pathway. This study underscores AG's potential as a therapeutic agent for ALI and provides new insights into its underlying mechanisms of action.

Role of toll-like receptor 4/mutant myeloid differentiation primary response 88/nuclear factor kappa-B mediated inflammation in diabetes mellitus with Northwest dryness syndrome.

OBJECTIVE: To investigate the role of toll-like receptor 4 (TLR4)/mutant myeloid differentiation primary response 88 (MyD88)/nuclear factor kappa-B (NF-κB) signaling pathway-mediated inflammation in diabetes mellitus with Northwest dryness syndrome. METHODS: Rats were randomly divided into the normal control, type 2 diabetes (T2DM) model, Northwest dryness syndrome + T2DM (Northwest dryness), and simple internal dampness + T2DM (internal dampness) groups. Enzyme-linked immunosorbent assay was used to detect biochemical indexes and inflammatory factors. The histopathological observation was performed. Quantitative real-time polymerase chain reaction and Western blot analysis were used to detect the mRNA and protein expression levels, respectively. RESULTS: Compared with the T2DM group, the glycosylated hemoglobin A1c, insulin, glucose tolerance, the homeostasis model assessment of insulin resistance, tumor necrosis factor-α, interleukin 1ß, interleukin 16, malondialdehyde, blood lipid, alanine aminotransferase, and aspartate aminotransferase were significantly elevated in the internal dampness group. Their levels were significantly elevated in the Northwest dryness group than in the T2DM and internal dampness groups. The superoxide dismutase, glutathione peroxidase, liver glycogen, and organ-to-weight ratio were significantly declined in the internal dampness group and the Northwest dryness group than in the T2DM group. However, these levels were elevated in the Northwest dryness group than in the internal dampness group. Moreover, the mRNA expression levels of interferon regulatory factor 5 and NF-κB p65, and the protein expression levels of TLR4, MyD88, and NF-κB were significantly higher in the internal dampness and the Northwest dryness groups than the T2DM group. Additionally, the mRNA and protein levels were significantly higher in the Northwest dryness group than in the internal dampness group. CONCLUSION: Northwest dryness syndrome-mediated TLR4/MyD88/NF-κB pathway and chronic inflammation might be associated with the occurrence and development of T2DM.

Rats Exposed to Excess Sucrose During a Critical Period Develop Inflammation and Express a Secretory Phenotype of Vascular Smooth Muscle Cells.

BACKGROUND: Neonatal rats that receive sucrose during a critical postnatal period (CP, days 12 to 28) develop hypertension by the time they reach adulthood. Inflammation might contribute to changes during this period and could be associated with variations in the vascular smooth muscle (VSMC) phenotype. OBJECTIVE: We studied changes in inflammatory pathways that could underlie the expression of the secretory phenotype in the VSMC in the thoracic aorta of rats that received sucrose during CP. METHODS: We analyzed histological changes in the aorta and the expression of the COX-2, TLR4, iNOS, eNOS, MMP-2 and -9, and ß- and α-actin, the quantities of TNF-α, IL-6, and IL-1ß using ELISA, and the levels of fatty acids using gas chromatography. RESULTS: The aortic wall presented disorganization, decellularization, and wavy elastic fibers and an increase in the lumen area. The α- and ß-actin expressions were decreased, while COX-2, TLR4, TNF-α, and the activity of IL-6 were increased. Oleic acid was increased in CP in comparison to the control group. CONCLUSIONS: There is transient hypertension at the end of the CP that is accompanied by inflammation and a change in the phenotype of VSMC to the secretory phenotype. The inflammatory changes could act as epigenetic signals to determine the development of hypertension when animals reach adulthood.

Allelic, Genotypic, and Haplotypic Analysis of Cytokine IL17A, IL17F, and Toll-like Receptor TLR4 Gene Polymorphisms in Metabolic-Dysfunction-Associated Steatotic Liver Disease: Insights from an Exploratory Study.

(1) Background: Interleukin 17 (IL17) and toll-like receptor 4 (TLR4) elevate the risk of metabolic and liver diseases. (2) Methods: This study's objective was to explore the association of IL17 and TLR4 gene polymorphisms with MASLD susceptibility and test their effect on serum IL17 and TLR4 levels. A total of 43 patients with MASLD (MASH/MAFL) and 38 healthy individuals were genotyped for IL17F-A7488G, IL17A-G197A, TLR4-Asp299Gly, and TLR4-Thr399Ile polymorphisms using PCR-RFLP. ELISA methods determined IL17F, IL17A, and TLR4 serum levels. (3) Conclusions: Patients carrying the variant genotypes (A/G + G/G) of IL17-A7448G (OR = 5.25), (G/A + A/A) of IL17-G197A (OR = 10.57), (Asp/Gly + Gly/Gly) of TLR4-Asp299Gly (OR = 3.52), or (Thr/Ile + Ile/Ile) of TLR4-Thr399Ile (OR = 9.87) had significantly increased odds of MASH. Genotype (G/A + A/A) of IL17-G197A was significantly associated with the odds of MAFL (p = 0.0166). Allele A of the IL17-G197A polymorphism was significantly related to increased odds of MAFL (OR = 4.13, p = 0.0133). In contrast, allele A of IL17-G197A (OR = 5.41, p = 0.008), allele Gly of TLR4-Asp299Gly (OR = 3.19, p = 0.046), and allele Ile of TLR4-Thr399Ile (OR = 6.94, p = 0.008) polymorphisms were significantly related to an increased risk of MASH. Allele A of IL17A-G197A, allele Gly of TLR4-Asp299Gly, and allele Ile of TLR4-Thr399Ile gene polymorphisms were significantly associated with the increased odds of MASLD. In patients with MASLD, we found significant influence from the IL17A-G197A gene polymorphism on IL17F levels (p = 0.0343).

Fosaprepitant improves cyclophosphamide-induced bladder damage by alleviating inflammatory response in mice.

Inhibition of inflammatory process is a key therapeutic target for the treatment of interstitial cystitis (IC). Recent reports indicate that neurokinin 1 receptor (NK1R) antagonists have beneficial roles in inflammatory-based diseases. Herein, we investigate the protective effects of fosaprepitant (FOS), a NK1R antagonist, in cyclophosphamide (CP)-induced cystitis. The cystitis model was established multiple CP (80 mg/kg; i.p.) injection one day apart, and mice were treated with FOS (20 and 60 mg/kg/day; i.p.) for seven consecutive days. Detrusor contractility, vesical vascular permeability, myeloperoxidase (MPO) activity and protein expression levels of the TLR4 pathway were evaluated in mice bladder. Carbachol and electric field stimulation-evoked contractions of detrusor strips were significantly increased in CP-treated mice, which was significantly attenuated by FOS (60 mg/kg/day) treatment (p<0.001, p<0.05). Notably, vesical vascular permeability was markedly impaired in CP-induced cystitis, that was restored by FOS (60 mg/kg/day) treatment (p<0.01). MPO activity was significantly increased in cystitis group whereas FOS (20 and 60 mg/kg/day) treatment remarkably suppressed MPO activity in bladder tissue (p<0.001). Although TLR4 expression increased with cystitis, MyD88 and p-NFκBSer536/total NFκB did not change, FOS (20 and 60 mg/kg/day) treatment caused a dramatic decrease in TLR4 expression (p<0.001), indicating the anti-inflammatory effect of FOS. In conclusion, FOS improved detrusor overactivity and inflammatory response by inhibiting MPO activity and TLR4 expression, resulting in functional and histological recovery in CP-induced cystitis.

Neuroinflammatory Pathways Associated with Chronic Post-Thoracotomy Pain: A Review of Current Literature.

Chronic post-thoracotomy pain (CPTP) is a major clinical problem that affects up to 35-55% of patients undergoing thoracic incisions. Evidence suggests that multiple cellular signaling pathways and neuro-inflammatory mediators may play an essential role in the pathogenesis of CPTP. In this comprehensive review, we present the current evidence on the cellular signaling pathways and inflammatory changes associated with the initiation and maintenance of CPTP, focusing on the potential application of these findings in the clinical setting. An electronic search of Medline, EMBASE, Cochrane, Google Scholar, and ClinicalTrials.gov was performed, and 3652 abstracts were identified. After an initial abstract screening, 131 studies underwent a full-text review, and nine papers were eventually included in this review. Studies were included if they assessed the cellular signaling pathways or inflammatory processes associated with the induction and/or maintenance of CPTP. All the identified studies were pre-clinical studies conducted on animal models. Our search identified seven cellular pathways (NK-1 receptor (NK-1), Glutaminase 1, Toll-like receptor 4 (TLR4), Resolvins, Ror-2, Sonic hedgehog signaling (Shh), and Wnt5a/Wnts) and six cytokines (IL-1ß, IL-6, IL-8, IL-10, IFN-γ, and TNF-α) that were investigated in the context of CPTP. Multiple cellular signaling pathways and inflammatory cytokines may play an important role in the neuroinflammatory changes associated with the induction and maintenance of chronic post-thoracotomy pain in animal models. However, the clinical impact and therapeutic utility of these neuroinflammatory changes in routine clinical practice have yet to be demonstrated.

Luteolin Mitigates Dopaminergic Neuron Degeneration and Restrains Microglial M1 Polarization by Inhibiting Toll Like Receptor 4.

BACKGROUND: Luteolin is a natural flavonoid and its neuroprotective and anti-inflammatory effects have been confirmed to mitigate neurodegeneration. Despite these findings, the underlying mechanisms responsible for these effects remain unclear. Toll-like receptor 4 (TLR4) is widely distributed in microglia and plays a pivotal role in neuroinflammation and neurodegeneration. Here studies are outlined that aimed at determining the mechanisms responsible for the anti-inflammatory and neuroprotective actions of luteolin using a rodent model of Parkinson's disease (PD) and specifically focusing on the role of TLR4 in this process. METHODS: The mouse model of PD used in this experiment was established through a single injection of lipopolysaccharide (LPS). Mice were then subsequently randomly allocated to either the luteolin or vehicle-treated group, then motor performance and dopaminergic neuronal injury were evaluated. BV2 microglial cells were treated with luteolin or vehicle saline prior to LPS challenge. MRNA expression of microglial specific marker ionized calcium-binding adapter molecule 1 (IBA-1) and M1/M2 polarization markers, as well as the abundance of indicated pro-inflammatory cytokines in the mesencephalic tissue and BV2 were quantified by real time-polymerase chain reaction (RT-PCR) and Enzyme-linked Immunosorbent Assay (ELISA), respectively. Cell viability and apoptosis of neuron-like PC12 cell line co-cultured with BV2 were detected. TLR4 RNA transcript and protein abundance in mesencephalic tissue and BV2 cells were detected. Nuclear factor kappa-gene binding (NF-κB) p65 subunit phosphorylation both in vitro and in vivo was evaluated by immunoblotting. RESULTS: Luteolin treatment induced functional improvements and alleviated dopaminergic neuronal loss in the PD model. Luteolin inhibited apoptosis and promoted cell survival in PC12 cells. Luteolin treatment shifted microglial M1/M2 polarization towards an anti-inflammatory M2 phenotype both in vitro and in vivo. Finally, it was found that luteolin treatment significantly downregulated both TLR4 mRNA and protein expression as well as restraining NF-κB p65 subunit phosphorylation. CONCLUSIONS: Luteolin restrained dopaminergic degeneration in vitro and in vivo by blocking TLR4-mediated neuroinflammation.

Paquinimod attenuates retinal injuries by suppressing the S100A9/TLR4 signaling in an experimental model of diabetic retinopathy.

Diabetic retinopathy (DR), the most common ocular complication of diabetes mellitus (DM), has exhibited an increase in incidence over the past decade. S100 calcium-binding protein A9 (S100A9) plays a significant role in inflammation and cancer. Toll-like receptor 4 (TLR4), a transmembrane receptor, initiates signaling cascades upon ligand binding. S100A9 activates TLR4, and their involvement in various diseases is well-established. We found elevated S100A9/TLR4 pathway proteins in the vitreous of DR patients. Bioinformatics analysis revealed differential gene expression related to this pathway. These proteins were also detected in diabetic rat retinas and induced structural damage. Paquinimod, an S100A9 inhibitor, decreased pathway protein expression and reduced retinal damage. Our study validates the S100A9/TLR4 pathway in diabetic retinas and suggests its potential as a therapeutic target for DR. Targeting S100A9 could offer a novel approach to prevention and treatment.

The senomorphic impact of astaxanthin on irradiated rat spleen: STING, TLR4 and mTOR contributed pathway.

OBJECTIVES: Exposure of spleen tissues to ionizing radiation during radiotherapy can induce cellular stress and immune-dysfunction leading to cellular senescence. INTRODUCTION: The process of a cancerous development is facilitated by the accumulation of senescent cells. This justifies the incorporation of anti-senescent medications during splenic irradiation (SI). METHODS: In this study senescence was induced in the spleen of male albino rats by radiation exposure (5Gy-single whole body gamma-irradiation) then after 2 weeks, oral astaxanthin regimen was started once daily in a dose of 25 mg/kg for 7 consecutive days. Concurrent control groups were carried out. RESULTS: the present data reflected that irradiation provoked an increase in the oxidative stress biomarkers (nitric oxide, lipid peroxidation and total reactive oxygen species levels)and the inflammatory biomarkers (Myeloperoxidase and interleukin-6). In addition irradiation led to the over expression of stimulator of interferon genes (cGAS-STING), mammalian target of rapamycin (mTOR) and Toll-like receptor 4 (TLR4) along with the lactate dehydrogenase (LDH), cyclin-dependent kinase inhibitor 1 (p21) cyclin-dependent kinase inhibitor 2A (p16) increment with elevation of tumor suppressor protein (p53) level. However, reduced glutathione contents and catalase activity were reduced post irradiation in spleen tissues, all these changes reflecting induction of cellular senescence. Astaxanthin treatment showed an improvement in the antioxidant/oxidative stress balance, inflammatory biomarkers, histopathological examination and immunohistochemical expressions of the tested proteins in the irradiated rats. CONCLUSION: the current findings offer a new insight into the senomorphic effect of astaxanthin following radiation-induced spleen senescence via STING, mTOR, and TLR4 signalling pathways.

25-hydroxycholesterol promotes brain cytokine production and leukocyte infiltration in a mouse model of lipopolysaccharide-induced neuroinflammation.

Neuroinflammation has been implicated in the pathogenesis of several neurologic and psychiatric disorders. Microglia are key drivers of neuroinflammation and, in response to different inflammatory stimuli, overexpress a proinflammatory signature of genes. Among these, Ch25h is a gene overexpressed in brain tissue from Alzheimer's disease as well as various mouse models of neuroinflammation. Ch25h encodes cholesterol 25-hydroxylase, an enzyme upregulated in activated microglia under conditions of neuroinflammation, that hydroxylates cholesterol to form 25-hydroxycholesterol (25HC). 25HC can be further metabolized to 7α,25-dihydroxycholesterol, which is a potent chemoattractant of leukocytes. We have previously shown that 25HC increases the production and secretion of the proinflammatory cytokine, IL-1ß, by primary mouse microglia treated with lipopolysaccharide (LPS). In the present study, wildtype (WT) and Ch25h-knockout (KO) mice were peripherally administered LPS to induce an inflammatory state in the brain. In LPS-treated WT mice, Ch25h expression and 25HC levels increased in the brain relative to vehicle-treated WT mice. Among LPS-treated WT mice, females produced significantly higher levels of 25HC and showed transcriptomic changes reflecting higher levels of cytokine production and leukocyte migration than WT male mice. However, females were similar to males among LPS-treated KO mice. Ch25h-deficiency coincided with decreased microglial activation in response to systemic LPS. Proinflammatory cytokine production and intra-parenchymal infiltration of leukocytes were significantly lower in KO compared to WT mice. Amounts of IL-1ß and IL-6 in the brain strongly correlated with 25HC levels. Our results suggest a proinflammatory role for 25HC in the brain following peripheral administration of LPS.

Toll-Like Receptor 4 (TLR4) Promotes DRG Regeneration and Repair after Sciatic Nerve Injury via the ERK-NF-kB Pathway.

Previously, we found that the expression of Toll-like receptor 4 (TLR4) is altered after sciatic nerve injury, and its differential expression plays a key role in recovery. However, the mechanisms by which TLR4 affects neuronal function in the dorsal root ganglion (DRG) have not been completely evaluated. The objective is to determine TLR4 expression in DRG tissues after sciatic neural injury and exploring the effects of TLR4 knockdown and overexpression in the DRG on neuronal function and nerve regeneration in rats in vivo and in vitro. We established a model of nerve injury and utilized molecular biology and cell biology experiments to explore the molecular mechanisms by which TLR4 in the DRG affects sciatic nerve restoration and regeneration after injury. Verified the localization of TLR4 in DRG neurons. Investigated pathways that related to apoptosis or nerve regeneration by which TLR4 regulates the function of DRG neurons. TLR4 expression was upregulated in the DRG tissues of rats after sciatic nerve injury. TLR4 overexpression promoted axon regeneration and inhibited apoptosis in DRG neurons. TLR4 promoted the regeneration of axons and the recovery of motor and sensory functions in the sciatic nerve after injury in vivo, and the data showed that TLR4 may regulate the function of DRG neurons and promote nerve repair and regeneration through the ERK and NF-κB signaling pathways in vivo and ex vivo. The study suggests that TLR4 may regulate the function of DRG neurons and promote nerve regeneration by affecting the ERK and NF-κB signaling pathways.

TLR4 promotes smooth muscle cell-derived foam cells formation by inducing receptor-independent macropinocytosis.

Foam cells are primarily formed through scavenger receptors that mediate the uptake of various modified low-density lipoproteins (LDL) into cells. In addition to the receptor-dependent pathway, macropinocytosis is an essential non-receptor endocytic pathway for vascular smooth muscle cells (VSMCs) to take up lipids. However, the molecular mechanisms underlying this process remain unclear. Primary cultured VSMCs were stimulated with 200 ng/ml lipopolysaccharide (LPS) and 200 µg/ml native LDL (nLDL). We observed a significant increase in TLR4 protein expression and a significant activation of macropinocytosis, which correlated with the highest uptake of nLDL and intracellular lipid deposition in WT VSMCs. However, macropinocytosis was inhibited and lipid accumulation decreased after treatment with macropinocytosis inhibitors and Syk inhibitors in WT VSMCs. Consistently, TLR4 knockout significantly suppressed macropinocytosis and lipid droplets accumulation in VSMCs. Taken together, our findings suggest a critical role of TLR4/Syk signaling in promoting receptor-independent macropinocytosis leading to VSMC-derived foam cells formation.