TLR4-IN-C34 Inhibits Lipopolysaccharide-Stimulated Inflammatory Responses via Downregulating TLR4/MyD88/NF-κB/NLRP3 Signaling Pathway and Reducing ROS Generation in BV2 Cells

Role of pattern recognition receptors in the development of MASLD and potential therapeutic applications

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become one of the most prevalent liver diseases worldwide, and its occurrence is strongly associated with obesity, insulin resistance (IR), genetics, and metabolic stress. Ranging from simple fatty liver to metabolic dysfunction-associated steatohepatitis (MASH), even to severe complications such as liver fibrosis and advanced cirrhosis or hepatocellular carcinoma, the underlying mechanisms of MASLD progression are complex and involve multiple cellular mediators and related signaling pathways. Pattern recognition receptors (PRRs) from the innate immune system, including Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), RIG-like receptors (RLRs), and DNA receptors, have been demonstrated to potentially contribute to the pathogenesis for MASLD. Their signaling pathways can induce inflammation, mediate oxidative stress, and affect the gut microbiota balance, ultimately resulting in hepatic steatosis, inflammatory injury and fibrosis. Here we review the available literature regarding the involvement of PRR-associated signals in the pathogenic and clinical features of MASLD, in vitro and in animal models of MASLD. We also discuss the emerging targets from PRRs for drug developments that involved agent therapies intended to arrest or reverse disease progression, thus enabling the refinement of therapeutic targets that can accelerate drug development.

A mosquito salivary protein-driven influx of myeloid cells facilitates flavivirus transmission

Mosquitoes transmit many disease-relevant flaviviruses. Efficient viral transmission to mammalian hosts requires mosquito salivary factors. However, the specific salivary components facilitating viral transmission and their mechanisms of action remain largely unknown. Here, we show that a female mosquito salivary gland-specific protein, here named A. aegypti Neutrophil Recruitment Protein (AaNRP), facilitates the transmission of Zika and dengue viruses. AaNRP promotes a rapid influx of neutrophils, followed by virus-susceptible myeloid cells toward mosquito bite sites, which facilitates establishment of local infection and systemic dissemination. Mechanistically, AaNRP engages TLR1 and TLR4 of skin-resident macrophages and activates MyD88-dependent NF-κB signaling to induce the expression of neutrophil chemoattractants. Inhibition of MyD88-NF-κB signaling with the dietary phytochemical resveratrol reduces AaNRP-mediated enhancement of flavivirus transmission by mosquitoes. These findings exemplify how salivary components can aid viral transmission, and suggest a potential prophylactic target.

Gadolinium-Based Magnetic Resonance Theranostic Agent with Gallic Acid as an Anti-Neuroinflammatory and Antioxidant Agent

Studies in the field have actively pursued the incorporation of diverse biological functionalities into gadolinium-based contrast agents, aiming at the amalgamation of MRI imaging and therapeutic capabilities. In this research, we present the development of Gd-Ga, an anti-neuroinflammatory MR contrast agent strategically designed to target inflammatory mediators for comprehensive imaging diagnosis and targeted lesion treatment. Gd-Ga is a gadolinium complex composed of 1,4,7-tris(carboxymethylaza)cyclododecane-10-azaacetylamide (DO3A) conjugated with gallic acid (3,4,5-trihydroxybenzoic acid). Upon intravenous administration in LPS-induced mouse models, Gd-Ga demonstrated a remarkable three-fold increase in signal-to-noise (SNR) variation compared to Gd-DOTA, particularly evident in both the cortex and hippocampus 30 min post-MR monitoring. In-depth investigations, both in vitro and in vivo, into the anti-neuroinflammatory properties of Gd-Ga revealed significantly reduced protein expression levels of pro-inflammatory mediators compared to the LPS group. The alignment between in silico predictions and phantom studies indicates that Gd-Ga acts as an anti-neuroinflammatory agent by directly binding to MD2. Additionally, the robust antioxidant activity of Gd-Ga was confirmed by its effective scavenging of NO and ROS. Our collective findings emphasize the immense potential of this theranostic complex, where a polyphenol serves as an anti-inflammatory drug, presenting an exceptionally efficient platform for the diagnosis and treatment of neuroinflammation.

Microglial TLR4/NLRP3 Inflammasome Signaling in Alzheimer's Disease

Alzheimer's disease is a pervasive neurodegenerative disease that is estimated to represent approximately 70% of dementia cases worldwide, and the molecular complexity that has been highlighted remains poorly understood. The accumulation of extracellular amyloid-β (Aβ), intracellular neurofibrillary tangles formed by tau hyperphosphorylation, and neuroinflammation are the major pathological features of Alzheimer's disease (AD). Over the years, there has been no apparent breakthrough in drug discovery based on the Aβ and tau hypotheses. Neuroinflammation has gradually become a hot spot in AD treatment research. As the primary cells of innate immunity in the central nervous system, microglia play a key role in neuroinflammation. Toll-like receptor 4 (TLR4) and nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasomes are vital molecules in neuroinflammation. In the pathological context of AD, the complex interplay between TLR4 and the NLRP3 inflammasomes in microglia influences AD pathology via neuroinflammation. In this review, the effect of the activation and inhibition of TLR4 and NLRP3 in microglia on AD pathology, as well as the cross-talk between TLR4 and the NLRP3 inflammasome, and the influence of essential molecules in the relevant signaling pathway on AD pathology, were expounded. In addition, the feasibility of these factors in representing a potential treatment option for AD has been clarified.

Advances in research on potential inhibitors of multiple myeloma

Multiple myeloma (MM) is a common hematological malignancy. Although recent clinical applications of immunomodulatory drugs, proteasome inhibitors and CD38-targeting antibodies have significantly improved the outcome of MM patient with increased survival, the incidence of drug resistance and severe treatment-related complications is gradually on the rise. This review article summarizes the characteristics and clinical investigations of several MM drugs in clinical trials, including their structures, mechanisms of action, structure-activity relationships, and clinical study progress. Furthermore, the application potentials of the drugs that have not yet entered clinical trials are also reviewed. The review also outlines the future directions of MM drug development.

MUC1 attenuates neutrophilic airway inflammation in asthma by reducing NLRP3 inflammasome-mediated pyroptosis through the inhibition of the TLR4/MyD88/NF-κB pathway

BACKGROUND

Neutrophilic airway inflammation is a challenge in asthma management and is associated with poor patient prognosis. Mucin 1 (MUC1), which contains a cytoplasmic tail (MUC1-CT), has been found to mediate glucocorticoid sensitivity in asthma; however, its role in modulating neutrophilic airway inflammation in asthma remains unknown.

METHODS

Human-induced sputum cells were collected from healthy participants (n = 12), patients with mild-to-moderate asthma (n = 34), and those with severe asthma (n = 18). In vitro human lung bronchial 1 epithelial cell line (BEAS-2B) was transfected with small interfering RNA against MUC1 (MUC1-siRNA) and then stimulated by lipopolysaccharide (LPS), where some cells were pretreated with a TLR4 inhibitor (TAK-242). In vivo mouse model of asthmatic neutrophil airway inflammation was induced by ovalbumin (OVA)/LPS. Some groups were intraperitoneally injected with MUC1-CT inhibitor (GO-203) and/or TAK-242 .

RESULTS

The mRNA expression of MUC1 was downregulated in the induced sputum of patients with asthma and correlated with asthmatic neutrophilic airway inflammation. The mRNA expressions of TLR4, MyD88, nucleotide-binding oligomerization domain-like pyrin domain-containing protein 3 (NLRP3), caspase-1, interleukin (IL)-18, and IL-1β in induced sputum cells of patients with asthma were upregulated and related to the mRNA expression of MUC1. LPS activated the TLR4 pathway and NLRP3-mediated pyroptosis in BEAS-2B cells in vitro, which were significantly aggravated after MUC1-siRNA transfection. Furthermore, MUCl-CT interacted with TLR4, and the interaction between TLR4 and MyD88 was significantly increased after MUCl-siRNA transfection. Moreover, TAK-242 ameliorated TLR4/MyD88/nuclear factor kappa B (NF-κB) pathway activation, NLRP3 inflammasome-mediated pyroptosis, and neutrophilic inflammation exacerbated by MUC1 downregulation. GO-203 exacerbated TLR4/MyD88/NF-κB pathway activation in vivo, and NLRP3 inflammasome-mediated pyroptosis reduced in a mouse model of asthmatic neutrophil airway inflammation induced by OVA/LPS; these pathological changes were partially alleviated after TAK-242 application.

CONCLUSION

This study revealed that MUC1 downregulation plays an important role in asthmatic neutrophilic airway inflammation. MUC1-CT reduces NLRP3 inflammasome-mediated pyroptosis by inhibiting the activation of the TLR4/MyD88/NF-κB pathway, thereby attenuating neutrophil airway inflammation in patients with asthma.

Inhibition of inflammatory factor TNF-α by ferrostatin-1 in microglia regulates necroptosis of oligodendrocyte precursor cells

OBJECTIVE

Inflammation of the surrounding environment is a major reason causing loss or injury of oligodendrocyte precursor cells (OPCs) in myelin-associated diseases. Lipopolysaccharide-activated microglia can release various inflammatory factors such as tumor necrosis factor-α (TNF-α). One of the ways of OPC death is necroptosis, which can be triggered by TNF-α, a death receptor ligand, by activating receptor-interacting protein kinase 1 (RIPK1)/RIPK3/mixed lineage kinase domain-like protein (MLKL) signaling pathway. This study investigated whether inhibiting microglia ferroptosis can decrease TNF-α release to alleviate OPC necroptosis.

METHODS

Lipopolysaccharide and Fer-1 stimulate BV2 cells. The expressions of GPX4 and TNF-α were detected by western blot and quantitative real-time PCR; malondialdehyde, glutathione, iron, and reactive oxygen species were measured by the assay kits. After lipopolysaccharide stimulation of BV2 cells, the supernatant was taken to culture OPC. The protein expression levels of RIPK1, p-RIPK1, RIPK3, p-RIPK3, MLKL, and p-MLKL were detected by western blot.

RESULTS

Lipopolysaccharide administration could induce ferroptosis in microglia by decreasing ferroptosis marker GPX4, while ferroptosis inhibitor Fer-1 could significantly increase GPX4 level. Fer-1 prevented oxidative stress and iron concentration elevation and alleviated mitochondrial damage in lipopolysaccharide-induced BV2 cells. The results revealed that Fer-1 downregulated the release of lipopolysaccharide-induced TNF-α in microglia and attenuated OPC necroptosis by significantly decreasing the expression levels of RIPK1, p-RIPK1, MLKL, p-MLKL, RIPK3, and p-RIPK3.

CONCLUSION

Fer-1 may be a potential agent for inhibiting inflammation and treating myelin-related diseases.

Spinal alarmin HMGB1 and the activation of TLR4 lead to chronic stress-induced nociceptive hypersensitivity in rodents

Chronic stress affects millions of people around the world, and it can trigger different behavioral disorders like nociceptive hypersensitivity and anxiety, among others. However, the mechanisms underlaying these chronic stress-induced behavioral disorders have not been yet elucidated. This study was designed to understand the role of high-mobility group box-1 (HMGB1) and toll-like receptor 4 (TLR4) in chronic stress-induced nociceptive hypersensitivity. Chronic restraint stress induced bilateral tactile allodynia, anxiety-like behaviors, phosphorylation of ERK and p38MAPK and activation of spinal microglia. Moreover, chronic stress enhanced HMGB1 and TLR4 protein expression at the dorsal root ganglion, but not at the spinal cord. Intrathecal injection of HMGB1 or TLR4 antagonists reduced tactile allodynia and anxiety-like behaviors induced by chronic stress. Additionally, deletion of TLR4 diminished the establishment of chronic stress-induced tactile allodynia in male and female mice. Lastly, the antiallodynic effect of HMGB1 and TLR4 antagonists were similar in stressed male and female rats and mice. Our results suggest that chronic restraint stress induces nociceptive hypersensitivity, anxiety-like behaviors, and up-regulation of spinal HMGB1 and TLR4 expression. Blockade of HMGB1 and TLR4 reverses chronic restraint stress-induced nociceptive hypersensitivity and anxiety-like behaviors and restores altered HMGB1 and TLR4 expression. The antiallodynic effects of HMGB1 and TLR4 blockers in this model are sex independent. TLR4 could be a potential pharmacological target for the treatment of the nociceptive hypersensitivity associated with widespread chronic pain.

What type of cell death occurs in chronic cerebral hypoperfusion? A review focusing on pyroptosis and its potential therapeutic implications

Chronic cerebral hypoperfusion (CCH) is a major global disease with chronic cerebral blood flow reduction. It is also the main cause of cognitive impairment and neurodegenerative diseases. Pyroptosis, a novel form of cell death, is characterized by the rupture of the cell membrane and the release of pro-inflammatory mediators. In recent years, an increasing number of studies have identified the involvement of pyroptosis and its mediated inflammatory response in the pathological process of CCH. Therefore, preventing the activation of pyroptosis following CCH is beneficial to inhibit the inflammatory cascade and reduce brain injury. In this review, we discuss the research progress on the relationship between pyroptosis and CCH, in order to provide a reference for research in related fields.

Advanced development and mechanism of sepsis-related acute respiratory distress syndrome

The introduction of the Sepsis 3.0 guidelines in 2016 improved our understanding of sepsis diagnosis and therapy. Personalized treatment strategies and nursing methods for sepsis patients are recommended in the "Save Sepsis Campaign" in 2021. However, mortality in sepsis patients remains high. Patients with sepsis-related acute respiratory distress syndrome account for around 30% of them, with fatality rates ranging from 30 to 40%. Pathological specimens from individuals with sepsis-related ARDS frequently demonstrate widespread alveolar damage, and investigations have revealed that pulmonary epithelial and pulmonary endothelial injury is the underlying cause. As a result, the purpose of this work is to evaluate the mechanism and research progress of pulmonary epithelial and pulmonary endothelial damage in sepsis-related ARDS, which may provide new directions for future research, diagnosis, and therapy.

Tabersonine Inhibits the Lipopolysaccharide-Induced Neuroinflammatory Response in BV2 Microglia Cells via the NF-κB Signaling Pathway

The occurrence and development of neurodegenerative diseases is related to a variety of physiological and pathological changes. Neuroinflammation is one of the major factors that induces and aggravates neurodegenerative diseases. The most important manifestation of neuroinflammation is the activation of microglia. Therefore, inhibiting the abnormal activation of microglia is an important way to alleviate the occurrence of neuroinflammatory diseases. In this research, the inhibitory effect of tabersonine (Tab) on neuroinflammation was evaluated by establishing the BV2 neuroinflammation model induced by lipopolysaccharide (LPS). It was found that Tab significantly inhibited the production and expression of nitric oxide (NO), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and reactive oxygen species (ROS) in BV-2 cells stimulated by LPS. In addition, Tab can also inhibit the activation of nuclear factor-κB (NF-κB) induced by LPS, thus regulating inflammatory mediators such as inducible nitric oxide synthase (iNOS). These results indicated that Tab regulated the release of inflammatory mediators such as NO, IL-1β, TNF-α, and IL-6 by inhibiting NF-κB signaling pathway, and exerting its anti-neuroinflammatory effect. This is the first report regarding the inhibition on LPS-induced neuroinflammation in BV2 microglia cells of Tab, which indicated the drug development potential of Tab for the treatment of neurodegenerative diseases.

Network Pharmacology Analysis and Experimental Validation of Kaempferol in the Treatment of Ischemic Stroke by Inhibiting Apoptosis and Regulating Neuroinflammation Involving Neutrophils

Kaempferol, a natural plant flavonoid compound, has a neuroprotective effect on ischemic stroke, while the specific mechanism remains unclear. In the current study, we applied the comprehensive strategy that combines network pharmacology and experimental evaluation to explore the potential mechanism of kaempferol in the treatment of cerebral ischemia. First, network pharmacology analysis identified the biological process of kaempferol, suggesting that kaempferol may partly help in treating ischemic stroke by regulating apoptosis and inflammatory response. Then, we evaluated the efficacy of kaempferol in the acute stage of ischemic stroke and elucidated its effects and possible mechanisms on cell apoptosis and neuroinflammation involved by neutrophils. The results showed that kaempferol could significantly reduce the modified neurological severity score (mNSS), and reduce the volume of cerebral infarction and the degree of cerebral edema. In terms of anti-apoptosis, kaempferol could significantly reduce the number of TUNEL-positive cells, inhibit the expression of pro-apoptotic proteins and promote the expression of anti-apoptotic proteins. Kaempferol may play an anti-apoptotic role by up-regulating the expression level of the BDNF-TrkB-PI3K/AKT signaling pathway. In addition, we found that kaempferol inhibited neuron loss and the activation of glial cells, as well as the expression level of the inflammatory protein COX-2 and the classic pro-inflammatory signaling pathway TLR4/MyD88/NF-κB in the ischemic brain, reduced MPO activity and neutrophil counts in peripheral blood, and down-regulated neutrophil aggregation and infiltration in the ischemic brain. Western blot revealed that kaempferol down-regulated the activation of the JAK1/STAT3 signaling pathway in neutrophils and ischemic brains. Our study showed that kaempferol inhibited the activation and number of neutrophils in the rat peripheral blood and brain, which may be related to the down-regulation of the JAK1/STAT3 pathway.

Effects of Dietary Macleaya cordata Extract Containing Isoquinoline Alkaloids Supplementation as an Alternative to Antibiotics in the Diets on Growth Performance and Liver Health of Broiler Chickens

This study aimed to investigate the effects of dietary supplementation with Macleaya cordata extract (MCE) containing protopine and allotypotopine on the growth performance and liver health in broiler chickens. A total of 486 1-day-old male AA broiler chickens were randomly assigned to the following three groups: (1) control (CON) group, broiler chickens fed a basal diet; (2) AGP group (positive control), broiler chickens fed a basal diet supplemented with 50 mg/kg aureomycin; (3) MCE group, broiler chickens fed a basal diet supplemented with 0.6 mg/kg MCE including 0.4 mg/kg protopine and 0.2 mg/kg allotypotopine. The results showed that the MCE group had significantly higher final body weight and average daily gain from d 0 to 42 than the other groups (p < 0.05), and groups MCE and AGP both had significantly lower feed-to-gain ratio from d 0 to 42 than the CON group (p < 0.05). Serum total protein, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, total cholesterol, glucose, immunoglobulin A, immunoglobulin M, and complements (C3, C4) concentrations in the MCE group were significantly higher than in the CON group (p < 0.05). Dietary MCE or aureomycin supplementation significantly reduced the hepatic contents of 8-hydroxy-2'-deoxyguanosine, malondialdehyde, interleukin (IL)-1β, IL-6, NLRs family pyrin domain containing 3 (NLRP3), and caspase-1 in the liver (p < 0.05). Moreover, MCE or aureomycin supplementation significantly inhibited mRNA expressions of Toll-like receptor 4, myeloid differentiation factor 88, nuclear factor-κB, and NLRP3, as well as the expression ratio of Bax to Bcl-2 mRNA (p < 0.05). Therefore, our study suggested that dietary supplementation with 0.6 mg/kg MCE containing protopine and allocryptopine improved growth performance and benefited liver health in broiler chickens possibly through inhibiting caspase-1-induced pyroptosis by inactivating TLR4/MyD88/NF-κB/NLRP3 signaling pathway, and provided support for the application of MCE containing protopine and allocryptopine as an alternative to antibiotics in the feed industry.

The novel anti-neuroinflammatory functional food CCL01, a mixture of Cuscuta seed extracts and Lactobacillus paracasei NK112

Neuroinflammation, which occurs due to microglia, is related to the pathogenesis of neurodegenerative disorders. Recently, the development of functional foods that down-regulate over-activated microglial cells to prevent the progression of neurodegenerative disorders has been proposed, since over-activated microglia induce a chronic source of neurotoxic factors and reduce neuronal survival. Thus, the anti-neuroinflammatory effects of a functional food mixture (CCL01) including Cuscuta seeds and Lactobacillus paracasei NK112 on lipopolysaccharide (LPS)-induced experimental models were investigated. In LPS-induced in vitro models, the expression levels of inflammatory mediators (e.g., inducible nitric oxide synthase, cyclooxygenase-2, nitric oxide, and prostaglandin E2) and pro-inflammatory cytokines (e.g., tumor necrosis factor-α, interleukin (IL)-1β, and IL-6) were decreased upon CCL01 treatment. CCL01 showed an anti-neuroinflammatory effect in LPS-induced microglial cells via the inhibition of the mitogen-activated protein kinase (MAPK)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway and the activation of the nuclear factor erythroid-2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. In the LPS-treated in vivo mouse models, the increased expression of ionized calcium binding adaptor molecule 1 (Iba-1), which indicates microglial activity, was markedly decreased upon treatment with CCL01 (50 and 200 mg kg^-1) in the hippocampus and cortex areas of the mouse brains in comparison with the LPS-injected group. In addition, the groups to which CCL01 was administered had significantly decreased plasma levels of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in the LPS-injected mouse models. Our data suggest that CCL01 may be a potential anti-neuroinflammatory agent that can prevent microglia overactivation, and it could be useful for developing functional foods.