The human toll signaling pathway: divergence of nuclear factor kappaB and JNK/SAPK activation upstream of tumor necrosis factor receptor-associated factor 6 (TRAF6)

Alterations of the gut microbiota in patients with diabetic nephropathy and its association with the renin-angiotensin system

Objective

Type 2 Diabetes Mellitus (T2DM) is a global health concern, with complications such as diabetic nephropathy (DN) affecting 16.6% of patients and contributing to end-stage renal failure. Emerging research suggests that gut microbial communities may influence DN progression, potentially through mechanisms involving the renin-angiotensin system (RAS). This study aimed to evaluate changes in specific microbial genera in individuals with T2DM, both with and without DN, and to explore their associations with renal function markers and RAS activation.

Methods

A total of 120 participants were categorized into three groups: healthy controls, T2DM without DN, and T2DM with DN. Microbial abundances of genera including Escherichia, Prevotella, Bifidobacterium, Lactobacillus, Roseburia, Bacteroides, Faecalibacterium, and Akkermansia were quantified using qPCR targeting the bacterial 16 S rRNA gene. Gene expression levels of RAS-associated markers (ACE, AGT1R, AT2R, and Ang II) and inflammation-related genes (TNF-α, TLR4) were analyzed in peripheral blood mononuclear cells via qPCR.

Results

The study identified significant alterations in microbial composition. Genera such as Faecalibacterium, Akkermansia, Roseburia (butyrate producers), and Bifidobacterium (a potential probiotic) were markedly reduced in T2DM and DN groups compared to controls. Increased mRNA expression of RAS-related genes, including ACE, AGT1R, and Ang II, was observed in these groups. We also foun correlations between altered microbial genera, RAS gene expression, and clinical markers of renal dysfunction.

Conclusion

The findings suggest that specific microbial genera may influence the pathogenesis of DN through RAS activation and inflammatory pathways. These insights highlight potential therapeutic targets for mitigating DN progression in T2DM patients.

Effects of Environmentally Friendly Aquaculture Chamber Coatings on Enzyme Activities, Histology, and Transcriptome in the Liver of Larimichthys crocea

Aquaculture vessels have emerged as a sustainable alternative to traditional offshore aquaculture. However, the biological impacts of protective coatings used for vessel interiors are still poorly understood. This study assessed acute stress responses of Larimichthys crocea to epoxy-based aquaculture coatings using actual culture (1-fold) and high-exposure (80-fold) concentrations. Liver analyses included antioxidant enzymes, histopathology, and transcriptomics over 12-96 h. Firstly, the effect of the 80-fold concentration group on the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) was more significant in the liver of L. crocea compared to the 1-fold concentration group. Similarly, histological observations revealed that the 80-fold concentration group produced more significant pathological changes in the liver than the 1-fold concentration group, including hepatocyte damage and vacuolization. Subsequently, through high-throughput sequencing, a total of 714.02 million clean reads were obtained, with 693.71 million of these reads successfully mapped onto the reference genome of L. crocea, identifying 13,709 differentially expressed genes (DEGs). KEGG pathway enrichment analysis showed that many DEGs following coating-treated were involved in protein processing in endoplasmic reticulum, oxidative phosphorylation, cytokine-cytokine receptor interaction, FoxO signaling pathway, and toll-like receptor signaling pathway. Finally, fifteen DEGs were selected for quantitative real-time PCR (qRT-PCR) analysis, and the results showed a significant correlation with RNA-seq results, verifying the reliability and accuracy of the high-throughput sequencing data. This study preliminarily revealed the stress responses induced by aquaculture vessel coatings in L. crocea and provided fundamental data into the scientific use of coatings on aquaculture vessels.

Quercetin attenuates SiO2-induced ZBP-1-mediated PANoptosis in mouse neuronal cells via the ROS/TLR4/NF-κb pathway

With the increasing development of the society, silicon dioxide (SiO2) has been used in various fields, such as agriculture, food industry, etc., and its residues can pose a potential health threat to organisms. Quercetin (Que) is a potent free radical scavenger commonly found in plants. C57BL/6 mice were chosen to established a mouse model of SiO2 exposure and Que antagonism to investigate the mechanism of action of Que in rescuing the toxic damage of SiO2 on mouse cerebellum tissue. The results showed that cytoplasmic vacuolization, and inflammatory cell infiltration caused by SiO2 were alleviated by the addition of Que, and reduced oxidative stress in mouse cerebellum, alleviated the activation of TLR4 pathway induced by SiO2, and substantially reduced the occurrence of ZBP-1-mediated PANoptosis induced by SiO2 exposure in mouse cerebellum. In NS20Y cells, the oxidative stress activator (Elesclomol) and inhibitor N-acetyl cysteine (NAC), and the NF-κB activator 2 (NA2) were added. Elesclomol and NAC confirm the involvement of ROS in regulating the TLR4/NF-κB pathway, the TLR4/NF-κB pathway regulated ZBP-1-mediated PANoptosis in cerebellum and NS20Y cells induced by SiO2 exposure. In conclusion, the present experimental data suggest that Que mitigates the onset of ZBP-1-mediated PANoptosis in neuronal cells induced by SiO2 through the ROS/TLR4/NF-κB pathway. The present experimental findings help to understand the detoxification effect of Que in more tissues and provide an important reference for the rescue of organisms in long-term SiO2 environment.

TLR4/TNFR1 blockade suppresses STAT1/STAT3 expression and increases SOCS3 expression in modulation of LPS-induced macrophage responses

Due to the urgent need to create appropriate treatment techniques, which are currently unavailable, LPS-induced sepsis has become a serious concern on a global scale. The primary active component in the pathophysiology of inflammatory diseases such as sepsis is the Gram-negative bacterial lipopolysaccharide (LPS). LPS interacts with cell surface TLR4 in macrophages, causing the formation of reactive oxygen species (ROS), TNF-α, IL-1β and oxidative stress. It also significantly activates the MAPKs and NF-κB pathway. Excessive production of pro-inflammatory cytokines is one of the primary characteristic features in the onset and progression of inflammation. Cytokines mainly signal through the JAK/STAT pathway. We hypothesize that blocking of TLR4 along with TNFR1 might be beneficial in suppressing the effects of STAT1/STAT3 due to the stimulation of SOCS3 proteins. Prior to the LPS challenge, the macrophages were treated with antibodies against TLR4 and TNFR1 either individually or in combination. On analysis of the macrophage populations by flowcytometry, it was seen that receptor blockade facilitated the phenotypic shift of the M1 macrophages towards M2 resulting in lowered oxidative stress. Blocking of TLR4/TNFR1 upregulated the SOCS3 and mTOR expressions that enabled the transition of inflammatory M1 macrophages towards the anti-inflammatory M2 phenotype, which might be crucial in curbing the inflammatory responses. Also the reduction in the production of inflammatory cytokines such as IL-6, IL-1β due to the reduction in the activation of the STAT1 and STAT3 molecules was observed in our combination treatment group. All these results indicated that neutralization of both TLR4 and TNFR1 might provide new insights in establishing an alternative therapeutic strategy for LPS-sepsis.

The Role of the TLR4-MyD88 Signaling Pathway in the Immune Response of the Selected Scallop Strain "Hongmo No. 1" to Heat Stress

The innate immunity of marine bivalves is challenged upon exposure to heat stress, especially with increases in the frequency and intensity of heat waves. TLR4 serves a classical pattern recognition receptor in recognizing pathogenic microorganisms and activating immune responses. In this study, three genes, HMTLR4, HMMyD88 and HMTRAF6, were characterized as homologs of genes in the TLR4-MyD88 signaling pathway in the selected scallop strain "Hongmo No. 1". According to RT-PCR, acute heat stress (32 °C) inhibited genes in the TLR4-MyD88 signaling pathway, and LPS stimulation-induced activation of TLR4-MyD88 signal transduction was also negatively affected at 32 °C. ELISA showed LPS-induced tumor necrosis factor alpha (TNF-α) or lysozyme (LZM) activity, but this was independent of temperature. RNA interference (RNAi) confirmed that HMTLR4 silencing suppressed the expression of its downstream gene, whether at 24 °C or at 32 °C. The level of TNF-α and the activity of LZM also decreased after injection with dsRNA, indicating a negative effect on the innate immunity of scallops. Additionally, acute heat stress affected the suppression of downstream gene expression when compared with that at 24 °C, which led us to the hypothesis that heat stress directly influences the downstream targets of HMTLR4. These results enrich the knowledge of scallop immunity under heat stress and can be beneficial for the genetic improvement of new scallop strains with higher thermotolerance.

Interleukin-1 receptor accessory protein (IL-1RAP): A magic bullet candidate for immunotherapy of human malignancies

IL-1, plays a role in some pathological inflammatory conditions. This pro-inflammatory cytokine also has a crucial role in tumorigenesis and immune responses in the tumor microenvironment (TME). IL-1 receptor accessory protein (IL-1RAP), combined with IL-1 receptor-1, provides a functional complex for binding and signaling. In addition to the direct role of IL-1, some studies demonstrated that IL1-RAP has essential roles in the progression, angiogenesis, and metastasis of solid tumors such as gastrointestinal tumors, lung carcinoma, glioma, breast and cervical cancers. This molecule also interacts with FLT-3 and c-Kit tyrosine kinases and is involved in the pathogenesis of hematological malignancies such as acute myeloid lymphoma. Additionally, IL-1RAP interacts with solute carrier family 3 member 2 (SLC3A2) and thereby increasing the resistance to anoikis and metastasis in Ewing sarcoma. This review summarizes the role of IL-1RAP in different types of cancers and discusses its targeting as a novel therapeutic approach for malignancies.

Vitis vinifera leaf extract liposomal Carbopol gel preparation's potential wound healing and antibacterial benefits: in vivo, phytochemical, and computational investigation

Vitis vinifera Egyptian edible leaf extract loaded on a soybean lecithin, cholesterol, and Carbopol gel preparation (VVL-liposomal gel) was prepared to maximize the in vivo wound healing and anti-MRSA activities for the crude extract, using an excision wound model and focusing on TLR-2, MCP-1, CXCL-1, CXCL-2, IL-6 and IL-1β, and MRSA (wound infection model, and peritonitis infection model). VVL-liposomal gel was stable with significant drug entrapment efficiency reaching 88% ± 3, zeta potential value ranging from -50 to -63, and a size range of 50-200 μm nm in diameter. The in vivo evaluation proved the ability of VVL-liposomal gel to gradually release the drugs in a sustained manner with greater complete wound healing effect and tissue repair after 7 days of administration, with a significant decrease in bacterial count compared with the crude extract. Phytochemical investigation of the crude extract of the leaves yielded fourteen compounds: two new stilbenes (1, 2), along with twelve known ones (3-14). Furthermore, a computational study was conducted to identify the genes and possible pathways responsible for the anti-MRSA activity of the isolated compounds, and inverse docking was used to identify the most likely molecular targets that could mediate the extract's antibacterial activity. Gyr-B was discovered to be the best target for compounds 1 and 2. Hence, VVL-liposomal gel can be used as a novel anti-dermatophytic agent with potent wound healing and anti-MRSA capacity, paving the way for future clinical research.

GPR108 is required for gambogic acid inhibiting NF-κB signaling in cancer

GPCRs are the most potential targets for drug discovery, however, their role in oncology is underappreciated and GPCR-based anti-cancer drug is not fully investigated. Herein, we identified GPR108, a GPCR protein described in innate immune system, is a potential therapeutic target of cancer. Depletion of GPR108 dramatically inhibited the survival of various cancers. Notably, TNFα activation of NF-κB was totally impaired after GPR108 knockout. We identified gambogic acid (GA), a natural prenylated xanthone, selectively targeting GPR108. Importantly, GA engaged with GPR108 and promoted its degradation, knockout of GPR108 remarkably blocked GA inhibition of NF-κB signaling. Furthermore, in vitro and in vivo assays demonstrated that GA was dependent on GPR108 to exert anti-cancer activity. Overall, our findings supported GPR108 as a promising therapeutic target of cancer, and provided a small molecule inhibitor GA directly and selectively targeting GPR108 for cancer therapy.

Stellate ganglion block reduces inflammation and improves neurological function in diabetic rats during ischemic stroke

Diabetes mellitus is an independent risk factor for ischemic stroke. Both diabetes mellitus and stroke are linked to systemic inflammation that aggravates patient outcomes. Stellate ganglion block can effectively regulate the inflammatory response. Therefore, it is hypothesized that stellate ganglion block could be a potential therapy for ischemic stroke in diabetic subjects. In this study, we induced diabetes mellitus in rats by feeding them a high-fat diet for 4 successive weeks. The left middle cerebral artery was occluded to establish models of ischemic stroke in diabetic rats. Subsequently, we performed left stellate ganglion block with 1% lidocaine using the percutaneous posterior approach 15 minutes before reperfusion and again 20 and 44 hours after reperfusion. Our results showed that stellate ganglion block did not decrease the blood glucose level in diabetic rats with diabetes mellitus but did reduce the cerebral infarct volume and the cerebral water content. It also improved the recovery of neurological function, increased 28-day survival rate, inhibited Toll like receptor 4/nuclear factor kappa B signaling pathway and reduced inflammatory response in the plasma of rats. However, injection of Toll like receptor 4 agonist lipopolysaccharide 5 minutes before stellate ganglion block inhibited the effect of stellate ganglion block, whereas injection of Toll like receptor 4 inhibitor TAK242 had no such effect. We also found that stellate ganglion block performed at night had no positive effect on diabetic ischemic stroke. These findings suggest that stellate ganglion block is a potential therapy for diabetic ischemic stroke and that it may be mediated through the Toll like receptor 4/nuclear factor kappa B signaling pathway. We also found that the therapeutic effect of stellate ganglion block is affected by circadian rhythm.

Dietary dihydroartemisinin supplementation alleviates intestinal inflammatory injury through TLR4/NOD/NF-κB signaling pathway in weaned piglets with intrauterine growth retardation

The aim of present study was to evaluate whether diets supplemented with dihydroartemisinin (DHA) could alleviate intestinal inflammatory injury in weaned piglets with intrauterine growth retardation (IUGR). Twelve normal birth weight (NBW) piglets and 12 piglets with IUGR were fed a basal diet (NBW-CON and IUCR-CON groups), and another 12 piglets with IUGR were fed the basal diet supplemented with DHA at 80 mg/kg (IUGR-DHA group) from 21 to 49 d of age. At 49 d of age, 8 piglets with similar body weight in each group were sacrificed. The jejunal and ileal samples were collected for further analysis. The results showed that IUGR impaired intestinal morphology, increased intestinal inflammatory response, raised enterocyte apoptosis and reduced enterocyte proliferation and activated transmembrane toll-like receptor 4 (TLR4)/nucleotide-binding and oligomerization domain (NOD)/nuclear factor-κB (NF-κB) signaling pathway. Dihydroartemisinin inclusion ameliorated intestinal morphology, indicated by increased villus height, villus height-to-crypt depth ratio, villus surface area and decreased villus width of piglets with IUGR (P < 0.05). Compared with NBW piglets, IUGR piglets supplemented with DHA exhibited higher apoptosis index and caspase-3 expression, and lower proliferation index and proliferating cell nuclear antigen expression in the intestine (P < 0.05). Dihydroartemisinin supplementation attenuated the intestinal inflammation of piglets with IUGR, indicated by increased concentrations of intestinal inflammatory cytokines and lipopolysaccharides (P < 0.05). In addition, DHA supplementation down-regulated the related mRNA expressions of TLR4/NOD/NF-κB signaling pathway and upregulated mRNA expressions of negative regulators of TLR4 and NOD signaling pathway in the intestine of piglets with IUGR (P < 0.05). Piglets in the IUGR-DHA group showed lower protein expressions of TLR4, phosphorylated NF-κB (pNF-κB) inhibitor α, nuclear pNF-κB, and higher protein expression of cytoplasmic pNF-κB in the intestine than those in the IUGR-CON group (P < 0.05). In conclusion, DHA supplementation could improve intestinal morphology, regulate enterocyte proliferation and apoptosis, and alleviate intestinal inflammation through TLR4/NOD/NF-κB signaling pathway in weaned piglets with IUGR.

Anti-inflammatory mechanisms of suppressors of cytokine signaling target ROS via NRF-2/thioredoxin induction and inflammasome activation in macrophages

Suppressors of cytokine signaling (SOCS) exhibit diverse anti-inflammatory effects. Since ROS acts as a critical mediator of inflammation, we have investigated the anti-inflammatory mechanisms of SOCS via ROS regulation in monocytic/macrophagic cells. Using PMA-differentiated monocytic cell lines and primary BMDMs transduced with SOCS1 or shSOCS1, the LPS/TLR4-induced inflammatory signaling was investigated by analyzing the levels of intracellular ROS, antioxidant factors, inflammasome activation, and pro-inflammatory cytokines. The levels of LPS-induced ROS and the production of pro-inflammatory cytokines were notably down-regulated by SOCS1 and up-regulated by shSOCS1 in an NAC-sensitive manner. SOCS1 up-regulated an ROS-scavenging protein, thioredoxin, via enhanced expression and binding of NRF-2 to the thioredoxin promoter. SOCS3 exhibited similar effects on NRF-2/thioredoxin induction, and ROS downregulation, resulting in the suppression of inflammatory cytokines. Notably thioredoxin ablation promoted NLRP3 inflammasome activation and restored the SOCS1-mediated inhibition of ROS and cytokine synthesis induced by LPS. The results demonstrate that the anti-inflammatory mechanisms of SOCS1 and SOCS3 in macrophages are mediated via NRF-2-mediated thioredoxin upregulation resulting in the downregulation of ROS sig-nal. Thus, our study supports the anti-oxidant role of SOCS1 and SOCS3 in the exquisite regulation of macrophage activation under oxidative stress.

A polysaccharide extracted from alfalfa activates splenic B cells by TLR4 and acts primarily via the MAPK/p38 pathway

Alfalfa polysaccharide (APS) has been proposed to exhibit growth-promoting and immune-enhancing bodily functions in vivo. However, little is known about its downstream immunomodulatory and intrinsic molecular mechanisms. Herein, mouse splenic lymphocytes were isolated to characterize the immunomodulatory effects and molecular mechanisms of APS in vitro. The results demonstrated that APS selectively improved the cell viability and IgM production of B cells, but no effects on T cell viability or secretion of IL-2, IL-4 and IFN-γ were observed in vitro. The receptor blocking assay showed that TLR4 was the primary receptor involved in APS-mediated B cell activation, which was confirmed by the results obtained using C57BL/10ScNJ (TLR4 gene-deficient) mice. Moreover, APS activated the TLR4-MyD88 signaling pathway at the translational level by significantly increasing the protein expression of TLR4 and MyD88. Downstream pathway blocking assay demonstrated that both the MAPK and NF-κB pathways were involved in APS-induced B cell activation. Additionally, APS significantly enhanced the phosphorylation of p38, ERK, and JNK and activated the nuclear translocation of the NF-κB p65 subunit. Therefore, we concluded that APS specifically activates the immune functions of splenic B cells by TLR4, acting through the MAPK and NF-κB signaling pathways, and potently activates the p38 pathway.

Probiotic Escherichia coli Nissle inhibits IL-6 and MAPK-mediated cardiac hypertrophy during STZ-induced diabetes in rats

Escherichia coli Nissle (EcN), a probiotic bacterium protects against several disorders. Multiple reports have studied the pathways involved in cardiac hypertrophy. However, the effects of probiotic EcN against diabetes-induced cardiac hypertrophy remain to be understood. We administered five weeks old Wistar male (271±19.4 g body weight) streptozotocin-induced diabetic rats with 10⁹ cfu of EcN via oral gavage every day for 24 days followed by subjecting the rats to echocardiography to analyse the cardiac parameters. Overexpressed interleukin (IL)-6 induced the MEK5/ERK5, JAK2/STAT3, and MAPK signalling cascades in streptozotocin-induced diabetic rats. Further, the upregulation of calcineurin, NFATc3, and p-GATA4 led to the elevation of hypertrophy markers, such as atrial and B-type natriuretic peptides. In contrast, diabetic rats supplemented with probiotic EcN exhibited significant downregulated IL-6. Moreover, the MEK5/ERK5 and JAK2/STAT3 cascades involved during eccentric hypertrophy and MAPK signalling, including phosphorylated MEK, ERK, JNK, and p-38, were significantly attenuated in diabetic rats after supplementation of EcN. Western blotting and immunofluorescence revealed the significant downregulation of NFATc3 and downstream mediators, thereby resulting in the impairment of cardiac hypertrophy. Taken together, the findings demonstrate that supplementing probiotic EcN has the potential to show cardioprotective effects by inhibiting diabetes-induced cardiomyopathies.

miR-489-3p inhibits TLR4/NF-κB signaling to prevent inflammation in psoriasis

Psoriasis is a chronic inflammatory skin disease whose etiology has not yet been determined. MicroRNAs (miRs) regulate the early stages of psoriasis and are targets for therapeutic intervention. The present study aimed to investigate the functional role of miR-489-3p in psoriasis. The present study first assessed the expression levels of miR-489-3p and Toll-like receptor (TLR)4 mRNA using reverse transcription-quantitative PCR, and also detected the protein expression levels of TLR4 and NF-κB via western blot analysis. TargetScan and miRDB target gene prediction tools were used to confirm the regulation of Toll-like receptor (TLR)4 by miR-489-3p. Moreover, a Cell Counting Kit (CCK)-8 assay was conducted to evaluate cell viability, while cell cycle and colony formation assays were performed to evaluate cell proliferation. Human keratinocytes (HaCaT) were co-transfected with TLR4-small interfering RNA and miR-489-3p-inhibitor plasmids, and analysis of cell proliferation and inflammatory cytokine secretion was performed using CCK-8 assay and ELISA. It was found that miR-489-3p expression was downregulated in patients with psoriasis. Bioinformatics analysis identified that TLR4 was a direct target of miR-489-3p. This was confirmed via luciferase reporter assays in HaCaT cells. The overexpression of miR-489-3p inhibited the TLR4/NF-κB signaling pathway and reduced cell proliferation. TLR4 silencing alleviated the effects of miR-489-3p, and enhanced cell proliferation and inflammatory cytokine secretion. Taken together, these data suggested that miR-489-3p may be a key effector of psoriasis, which promotes inflammatory responses by direct targeting of TLR4. miR-489-3p therefore represents a promising prognostic biomarker and therapeutic target for psoriasis treatment.

Cervus nippon var. mantchuricus water extract treated with digestive enzymes (CE) modulates M1 macrophage polarization through TLR4/MAPK/NF-κB signaling pathways on murine macrophages

The objective of this study was to investigate the effects of Cervus nippon var. mantchuricus water extract treated with digestive enzymes (CE) on the promotion of M1 macrophage polarization in murine macrophages. Macrophages polarize either to one phenotype after stimulation with LPS or IFN-γ or to an alternatively activated phenotype that is induced by IL-4 or IL-13. Cell viability of RAW264.7 cells was determined by WST-1 assay. NO production was measured by Griess assay. IL-6, IL-12, TNF-α, and iNOS mRNA levels were measured by RT-PCR. IL-6, IL-12, and IL-10 cytokine levels were determined by ELISA. TLR4/MAPK/NF-κB signaling in RAW264.7 cells was evaluated by western blotting. The level of NF-κB was determined by immunoblotting. CE induced the differentiation of M1 macrophages. CE promoted M1 macrophages to elevate NO production and cytokine levels. CE-stimulated M1 macrophages had enhanced IL-6, IL-12, and TNF-α. CE promoted M1 macrophages to activate TLR4/MAPK/NF-κB phosphorylation. M2 markers were downregulated, while M1 markers were upregulated in murine macrophages by CE. Consequently, CE has immunomodulatory activity and can be used to promote M1 macrophage polarization through the TLR4/MAPK/NF-κB signaling pathways.

Sterile inflammation in the pathogenesis of maturation failure of arteriovenous fistula

Chronic kidney disease is a widespread terminal illness that afflicts millions of people across the world. Hemodialysis is the predominant therapeutic management strategy for kidney failure and involves the external filtration of metabolic waste within the circulation. This process requires an arteriovenous fistula (AVF) for vascular access. However, AVF maturation failures are significant obstacles in establishing long-term vascular access for hemodialysis. Appropriate stimulation, activation, and proliferation of smooth muscle cells, proper endothelial cell orientation, adequate structural changes in the ECM, and the release of anti-inflammatory markers are associated with maturation. AVFs often fail to mature due to inadequate tissue repair and remodeling, leading to neointimal hyperplasia lesions. The transdifferentiation of myofibroblasts and sterile inflammation are possibly involved in AVF maturation failures; however, limited data is available in this regard. The present article critically reviews the interplay of various damage-associated molecular patterns (DAMPs) and the downstream sterile inflammatory signaling with a focus on the NLRP3 inflammasome. Improved knowledge concerning AVF maturation pathways can be unveiled by investigating the novel DAMPs and the mediators of sterile inflammation in vascular remodeling that would open improved therapeutic opportunities in the management of AVF maturation failures and its associated complications.

How are MCPIP1 and cytokines mutually regulated in cancer-related immunity?

Cytokines are secreted by various cell types and act as critical mediators in many physiological processes, including immune response and tumor progression. Cytokines production is precisely and timely regulated by multiple mechanisms at different levels, ranging from transcriptional to post-transcriptional and posttranslational processes. Monocyte chemoattractant protein-1 induced protein 1 (MCPIP1), a potent immunosuppressive protein, was first described as a transcription factor in monocytes treated with monocyte chemoattractant protein-1 (MCP-1) and subsequently found to possess intrinsic RNase and deubiquitinase activities. MCPIP1 tightly regulates cytokines expression via various functions. Furthermore, cytokines such as interleukin 1 beta (IL-1B) and MCP-1 and inflammatory cytokines inducer lipopolysaccharide (LPS) strongly induce MCPIP1 expression. Mutually regulated MCPIP1 and cytokines form a complicated network in the tumor environment. In this review, we summarize how MCPIP1 and cytokines reciprocally interact and elucidate the effect of the network formed by these components in cancer-related immunity with aim of exploring potential clinical benefits of their mutual regulation.

Lipopolysaccharide Recognition in the Crossroads of TLR4 and Caspase-4/11 Mediated Inflammatory Pathways

The innate immune response to lipopolysaccharide is essential for host defense against Gram-negative bacteria. In response to bacterial infection, the TLR4/MD-2 complex that is expressed on the surface of macrophages, monocytes, dendritic, and epithelial cells senses picomolar concentrations of endotoxic LPS and triggers the production of various pro-inflammatory mediators. In addition, LPS from extracellular bacteria which is either endocytosed or transfected into the cytosol of host cells or cytosolic LPS produced by intracellular bacteria is recognized by cytosolic proteases caspase-4/11 and hosts guanylate binding proteins that are involved in the assembly and activation of the NLRP3 inflammasome. All these events result in the initiation of pro-inflammatory signaling cascades directed at bacterial eradication. However, TLR4-mediated signaling and caspase-4/11-induced pyroptosis are largely involved in the pathogenesis of chronic and acute inflammation. Both extra- and intracellular LPS receptors-TLR4/MD-2 complex and caspase-4/11, respectively-are able to directly bind the lipid A motif of LPS. Whereas the structural basis of lipid A recognition by the TLR4 complex is profoundly studied and well understood, the atomic mechanism of LPS/lipid A interaction with caspase-4/11 is largely unknown. Here we describe the LPS-induced TLR4 and caspase-4/11 mediated signaling pathways and their cross-talk and scrutinize specific structural features of the lipid A motif of diverse LPS variants that have been reported to activate caspase-4/11 or to induce caspase-4/11 mediated activation of NLRP3 inflammasome (either upon transfection of LPS in vitro or upon infection of cell cultures with intracellular bacteria or by LPS as a component of the outer membrane vesicles). Generally, inflammatory caspases show rather similar structural requirements as the TLR4/MD-2 complex, so that a "basic" hexaacylated bisphosphorylated lipid A architecture is sufficient for activation. However, caspase-4/11 can sense and respond to much broader variety of lipid A variants compared to the very "narrow" specificity of TLR4/MD-2 complex as far as the number and the length of lipid chains attached at the diglucosamine backbone of lipid A is concerned. Besides, modification of the lipid A phosphate groups with positively charged appendages such as phosphoethanolamine or aminoarabinose could be essential for the interaction of lipid A/LPS with inflammatory caspases and related proteins.

Roles of Interactions Between Toll-Like Receptors and Their Endogenous Ligands in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Systemic juvenile idiopathic arthritis (JIA) and adult-onset Still’s disease (AOSD) are systemic inflammatory disorders that manifest as high-spiking fever, joint pain, evanescent skin rash, and organomegaly. Their pathogenesis is unclear, but inflammation is triggered by activation of the innate immune system with aberrant production of proinflammatory cytokines. Along with extrinsic factors, intrinsic pathways can trigger an unexpected immune response. Damage-associated molecular patterns (DAMPs) induce the activation of innate immune cells, leading to sterile inflammation in systemic JIA and AOSD. These endogenous proteins interact with Toll-like receptors (TLRs), which are pattern recognition receptors, and mediate immune signaling following stimulation by pathogen-associated molecular patterns and DAMPs. Several DAMPs, such as S100 proteins, play a role in the development or severity of systemic JIA and AOSD, in which their interactions with TLRs are altered. Also, the expression levels of genes encoding DAMPs contribute to the susceptibility to systemic JIA and AOSD. Herein, we review reports that TLR and DAMP signaling initiates and/or maintains the inflammatory response in systemic JIA and AOSD, and their correlations with the clinical characteristics of those diseases. In addition, we assess their utility as biomarkers or therapeutics for systemic JIA and AOSD.

MCPIP1 RNase and Its Multifaceted Role

Inflammation is an organism’s physiological response to harmful septic and aseptic stimuli. This process begins locally through the influx of immune system cells to the damaged tissue and the subsequent activation and secretion of inflammatory mediators to restore homeostasis in the organism. Inflammation is regulated at many levels, and one of these levels is post-transcriptional regulation, which controls the half-life of transcripts that encode inflammatory mediators. One of the proteins responsible for controlling the amount of mRNA in a cell is the RNase monocyte chemoattractant protein-induced protein 1 (MCPIP1). The studies conducted so far have shown that MCPIP1 is involved not only in the regulation of inflammation but also in many other physiological and pathological processes. This paper provides a summary of the information on the role of MCPIP1 in adipogenesis, angiogenesis, cell differentiation, cancer, and skin inflammation obtained to date.

Decursin negatively regulates LPS-induced upregulation of the TLR4 and JNK signaling stimulated by the expression of PRP4 in vitro

The current investigation was carried out to analyze the correlation of bacterial lipopolysaccharide (LPS) and pre-mRNA processing factor 4B (PRP4) in inducing inflammatory response and cell actin cytoskeleton rearrangement in macrophages (Raw 264.7) and colorectal (HCT116) as well as skin cancer (B16-F10) cells. Cell lines were stimulated with LPS, and the expression of PRP4 as well as pro-inflammatory cytokines and proteins like IL-6, IL-1β, TLR4, and NF-κB were assayed. The results demonstrated that LPS markedly increased the expression of PRP4, IL-6, IL-1β, TLR4, and NF-κB in the cells. LPS and PRP4 concomitantly altered the morphology of cells from an aggregated, flattened shape to a round shape. Decursin, a pyranocoumarin from Angelica gigas, inhibited the LPS and PRP4-induced inflammatory response, and reversed the induction of morphological changes. Finally, we established a possible link of LPS with TLR4 and JNK signaling, through which it activated PRP4. Our study provides molecular insights for LPS and PRP4-related pathogenesis and a basis for developing new strategies against metastasis in colorectal cancer and skin melanoma. Our study emphasizes that decursin may be an effective treatment strategy for various cancers in which LPS and PRP4 perform a critical role in inducing inflammatory response and morphological changes leading to cell survival and protection against anti-cancer drugs.

Polysaccharide from alfalfa activates RAW 264.7 macrophages through MAPK and NF-κB signaling pathways

Alfalfa polysaccharide (APS), a bioactive compound extracted from alfalfa, has been proposed to exhibit potential growth-promoting and immune-enhancing functions. But, little is known about the cellular immunomodulatory and intrinsic molecular mechanisms. Here we extracted the APS, and performed in vitro experiments to characterize the immunomodulatory functions as well as the molecular mechanisms of APS on RAW 264.7 macrophages cells. Chemical analyses showed that APS was mainly composed of fucose, arabinose, galactose, glucose, xylose, mannose, galacturonic acid and glucuronic acid. The results of in vitro assays demonstrated that 50 and 100 μg/mL APS increased the cell viability of RAW 264.7 cells. The secretion and gene expression of NO/iNOS, IL-6 and TNF-α in APS-induced macrophage cell were significantly enhanced. However, APS-induced TNF-α production was decreased by blocking the MAPK or NF-κB signaling pathways, especially for the blockade of p38. Moreover, APS enhanced the phosphorylation of p38, ERK, and JNK, promoted the degradation of IκBα, and increased the nuclear translocation of NF-κB p65 subunit. Therefore, we demonstrated that APS could improve the immune functions of RAW 264.7 macrophages cells by promoting the cell viability and increasing secretion and gene expressions of NO/iNOS, IL-6 and TNF-α through the MAPK and NF-κB signaling pathways.

Understanding early TLR signaling through the Myddosome

TLRs are expressed on the plasma and endosomal membranes of innate immune cells acting as sensors of foreign and inherent danger signals that threaten the host. Upon activation, TLRs facilitate the assembly of large intracellular oligomeric signaling complexes, termed Myddosomes, which initiate key signal transduction pathways to elicit critical inflammatory immune responses. The formation of the Myddosome is integral for TLR signaling; however, the molecular mechanisms controlling its formation, disassembly, and the subsequent proximal signaling events remain to be clearly defined. In this review, we present a brief overview of TLR signal transduction pathways, summarize the current understanding of the Myddosome and the proteins that comprise its structure, including MyD88 and members of the IL-1 receptor-associated kinase (IRAK) family. Finally, we will discuss recent advances and open questions regarding early TLR signaling in the context of the Myddosome complex.

Protective Effects of Lactic Acid Bacteria Against TLR4 Induced Inflammatory Response in Hepatoma HepG2 Cells Through Modulation of Toll-Like Receptor Negative Regulators of Mitogen-Activated Protein Kinase and NF-κB Signaling

The beneficial effects of probiotics in several liver diseases have been investigated in both animal and clinical models; however, the precise mechanisms responsible for their effects have not yet been elucidated. Gut transmitted endotoxins such as LPS have been shown to play critical roles in hepatic inflammation and injury. Therefore, in this study, we investigated the beneficial role of selected lactic acid bacteria (LABs) on reduction of hepatic steatosis (HS) and attenuation of LPS induced inflammatory response in vitro. Total cellular fluid (TCF) of LABs treatment reduced HS by decreasing the amount of lipid accumulation in vitro. Additionally, HepG2 cells exposed to LPS showed increased expression of exacerbated inflammatory cytokines, such as IL-6, CXCL8, CCL2, and TNF-α, but these effects were counteracted when cells were treated with TCF of LABs prior to LPS challenge. Moreover, TCF of LABs was able to modulate mRNA levels of TLR negative regulators and protein levels of p38 MAPK and p65 NF-κB transcription factors. However, these modulations were differed remarkably between both free fatty acid treated and untreated HepG2 cells. Heat-killed LABs were also indirectly suppressed THP-1 cells to produce higher level of IL-10, TLR4, and lower at genes level of TGF-β, IL-1β, and IL-6, and at protein level of TNF-α in response to LPS. Taken together, our findings indicate that selected LABs exhibit profound immunoregulatory effects on liver cells via modulation of TLR negative regulators of the MAPK and NF-κB pathways.

An Overview of Novel Dietary Supplements and Food Ingredients in Patients with Metabolic Syndrome and Non-Alcoholic Fatty Liver Disease

Metabolic syndrome (MetS) is characterized by interconnected factors related to metabolic disturbances, and is directly related to the occurrence of some diseases such as cardiovascular diseases and type 2 diabetes. MetS is described as one or both of insulin resistance and visceral adiposity, considered the initial causes of abnormalities that include hyperglycemia, elevated blood pressure, dyslipidemia, elevated inflammatory markers, and prothrombotic state, as well as polycystic ovarian syndrome in women. Other than in MetS, visceral adiposity and the pro-inflammatory state are also key in the development of non-alcoholic fatty liver disease (NAFLD), which is the most prevalent chronic liver disease in modern society. Both MetS and NAFLD are related to diet and lifestyle, and their treatment may be influenced by dietary pattern changes and the use of certain dietary supplements. This study aimed to review the role of food ingredients and supplements in the management of MetS and NAFLD specifically in human clinical trials. Moreover, bioactive compounds and polyunsaturated fatty acids (PUFAs) may be used as strategies for preventing the onset of and treatment of metabolic disorders, such as MetS and NAFLD, improving the inflammatory state and other comorbidities, such as obesity, dyslipidemias, and cardiovascular diseases (CVD).

The Ubiquitin E3 Ligase TRAF6 Exacerbates Ischemic Stroke by Ubiquitinating and Activating Rac1

Stroke is one of the leading causes of morbidity and mortality worldwide. Inflammation, oxidative stress, apoptosis, and excitotoxicity contribute to neuronal death during ischemic stroke; however, the mechanisms underlying these complicated pathophysiological processes remain to be fully elucidated. Here, we found that the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6) was markedly increased after cerebral ischemia/reperfusion (I/R) in mice. TRAF6 ablation in male mice decreased the infarct volume and neurological deficit scores and decreased proinflammatory signaling, oxidative stress, and neuronal death after cerebral I/R, whereas transgenic overexpression of TRAF6 in male mice exhibited the opposite effects. Mechanistically, we demonstrated that TRAF6 induced Rac1 activation and consequently promoted I/R injury by directly binding and ubiquitinating Rac1. Either functionally mutating the TRAF6 ubiquitination site on Rac1 or inactivating Rac1 with a specific inhibitor reversed the deleterious effects of TRAF6 overexpression during I/R injury. In conclusion, our study demonstrated that TRAF6 is a key promoter of ischemic signaling cascades and neuronal death after cerebral I/R injury. Therefore, the TRAF6/Rac1 pathway might be a promising target to attenuate cerebral I/R injury.SIGNIFICANCE STATEMENT Stroke is one of the most severe and devastating neurological diseases globally. The complicated pathophysiological processes restrict the translation of potential therapeutic targets into medicine. Further elucidating the molecular mechanisms underlying cerebral ischemia/reperfusion injury may open a new window for pharmacological interventions to promote recovery from stroke. Our study revealed that ischemia-induced tumor necrosis factor receptor-associated factor 6 (TRAF6) upregulation binds and ubiquitinates Rac1 directly, which promotes neuron death through neuroinflammation and neuro-oxidative signals. Therefore, precisely targeting the TRAF6-Rac1 axis may provide a novel therapeutic strategy for stroke recovery.

Wandering pathways in the regulation of innate immunity and inflammation

Tumor-associated macrophages (TAM) have served as a paradigm of cancer-related inflammation. Moreover, investigations on TAM have led to the dissection of macrophage plasticity and polarization and to the discovery and analysis of molecular pathways of innate immunity, in particular cytokines, chemokines and PTX3 as a prototypic fluid phase pattern recognition molecule. Mechanisms of negative regulation are complex and include decoy receptors, receptor antagonists, anti-inflammatory cytokines and the signalling regulator IL-1R8. In this review, topics and open issues in relation to regulation of innate immunity and inflammation are discussed: 1) how macrophage and neutrophil plasticity and polarization underlie diverse pathological conditions ranging from autoimmunity to cancer and may pave the way to innovative diagnostic and therapeutic approaches; 2) the key role of decoy receptors and negative regulators (e.g. IL-1R2, ACKR2, IL-1R8) in striking a balance between amplification of immunity and resolution versus uncontrolled inflammation and tissue damage; 3) role of humoral innate immunity, illustrated by PTX3, in resistance against selected microbes, regulation of inflammation and immunity and tissue repair, with implications for diagnostic and therapeutic translation.

Protective effects of amniotic fluid in the setting of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common life threatening condition affecting preterm infants. NEC occurs in 1-5% of all neonatal intensive care admissions and 5-10% of very low birth weight infants. The protective role of human breast milk (BM) has been well established. It has also been shown that amniotic fluid (AF) and BM have many similarities in terms of presence of growth and other immune-modulatory factors. This finding led to the initial hypothesis that AF may exert similar protective effects against the development of NEC, as does BM. Multiple studies have elucidated the presence of growth factors in AF and the protective effect of AF against NEC. Studies have also described possible mechanisms how AF protects against NEC. At present, research in this particular area is extremely active and robust. This review summarizes the various studies looking at the protective effects of AF against the development of NEC. It also provides an insight into future directions, the vast potential of AF as a readily available biologic medium, and the ethical barriers that must be overcome before using AF.

Interleukin-10 release from astrocytes suppresses neuronal apoptosis via the TLR2/NFκB pathway in a neonatal rat model of hypoxic-ischemic brain damage

The biological function of interleukin-10 (IL-10) and the relationship between IL-10 secretion and the Toll-like receptor 2 (TLR2) expression levels in the central nervous system following hypoxic-ischemic brain damage (HIBD) are poorly understood. Here, we intend to elucidate the biological function and mechanism of IL-10 secretion following HIBD. In this study, we used a neonatal rat model of HIBD and found that rats injected with adeno-associated virus-IL-10-shRNA (short hairpin RNA) exhibited partially impaired learning and memory function compared to rats administered adeno-associated virus-control-shRNA. In vitro oxygen-glucose deprivation (OGD) induced IL-10 release from astrocytes but not from neurons. Pretreatment with exogenous recombinant IL-10 alleviated OGD-mediated apoptosis of neurons but not astrocytes. In addition, we also observed that hypoxic injury induced a marked increase in IL-10 expression in astrocytes as a result of activation of the TLR2/phosphorylated nuclear factor kappa B (p-NFκB) p65 signaling cascade; furthermore, this effect disappeared upon small interfering RNA targeting rat TLR2 gene (siTLR2) treatment. Pyrrolidinedithiocarbamate, an inhibitor of NFκB activation, reduced the IL-10 expression levels in both OGD-injured astrocytes in vitro and the hippocampi of HIBD rats in vivo but did not significantly affect TLR2 expression. Furthermore, a luciferase assay revealed that p-NFκB p65 could bind the -1700/-1000 bp proximal region of the IL-10 gene promoter to regulate IL-10 secretion from astrocytes and that this interaction could be controlled by OGD treatment. These data suggest that HIBD induces IL-10 secretion from astrocytes to exert a paracrine-induced anti-apoptotic effect on injured neurons via the TLR2/NFκB signaling pathway, which may improve learning and memory dysfunction after ischemic injury.

The immune-enhancing activity of Cervus nippon mantchuricus extract (NGE) in RAW264.7 macrophage cells and immunosuppressed mice

Chemotherapeutics are often used to inhibit the proliferation of cancer cells. However, they can also harm healthy cells and cause side effects such as immunosuppression. Especially traditional oriental medicines long used in Asia, may be beneficial candidates for the alleviation of immune diseases. Cervus nippon mantchuricus extract (NGE) is currently sold in the market as coffee and health drinks. However, NGE was not widely investigated and efficacy remain unclear and essentially nothing is known about their potential immune-regulatory properties. As a result, NGE induced the differentiation of RAW264.7 macrophage cells. NGE-stimulated RAW264.7 macrophage cells elevated cytokines levels and NO production. NGE-stimulated RAW264.7 macrophage cells activated MAPKs and NF-κB signaling pathways. NGE encouraged the immuno-enhancing effects in immunosuppressed short-term treated with NGE mice model. NGE or Red ginseng encouraged the immuno-enhancing effects in immunosuppressed long-term treated with NGE mice model. Our data clearly show that NGE contains immune-enhancing activity and can be used to treat immunodeficiency.

The TLR4-TRIF pathway can protect against the development of experimental allergic asthma

The Toll-like receptor (TLR) adaptor proteins myeloid differentiating factor 88 (MyD88) and Toll, interleukin-1 receptor and resistance protein (TIR) domain-containing adaptor inducing interferon-β (TRIF) comprise the two principal limbs of the TLR signalling network. We studied the role of these adaptors in the TLR4-dependent inhibition of allergic airway disease and induction of CD4⁺ ICOS⁺ T cells by nasal application of Protollin™, a mucosal adjuvant composed of TLR2 and TLR4 agonists. Wild-type (WT), Trif^-/- or Myd88^-/- mice were sensitized to birch pollen extract (BPEx), then received intranasal Protollin followed by consecutive BPEx challenges. Protollin's protection against allergic airway disease was TRIF-dependent and MyD88-independent. TRIF deficiency diminished the CD4⁺ ICOS⁺ T-cell subsets in the lymph nodes draining the nasal mucosa, as well as their recruitment to the lungs. Overall, TRIF deficiency reduced the proportion of cervical lymph node and lung CD4⁺ ICOS⁺ Foxp3^- cells, in particular. Adoptive transfer of cervical lymph node cells supported a role for Protollin-induced CD4⁺ ICOS⁺ cells in the TRIF-dependent inhibition of airway hyper-responsiveness. Hence, our data demonstrate that stimulation of the TLR4-TRIF pathway can protect against the development of allergic airway disease and that a TRIF-dependent adjuvant effect on CD4⁺ ICOS⁺ T-cell responses may be a contributing mechanism.

Acemannan increases NF-κB/DNA binding and IL-6/-8 expression by selectively binding Toll-like receptor-5 in human gingival fibroblasts

Acemannan, an acetylated polymannose from Aloe vera, has immunomodulatory effects. We investigated whether acemannan induces IL-6 and -8 expression and NF-κB/DNA binding in human gingival fibroblasts. IL-6 and -8 expression levels were assessed via RT-PCR and ELISA. The NF-κB p50/p65-DNA binding was determined. The structures of acemannan mono-pentamers and Toll-like receptor 5 (TLR5) were simulated. The binding energies between acemannan and TLR5 were identified. We found that acemannan significantly stimulated IL-6/-8 expression at both the mRNA and protein level and significantly increased p50/DNA binding. Preincubation with an anti-TLR5 neutralizing antibody abolished acemannan-induced IL-6/-8 expression and p50/DNA binding, and co-incubation of acemannan with Bay11-7082, a specific NF- κB inhibitor, abolished IL-6/-8 expression. The computer modeling indicated that monomeric/dimeric single stranded acemannan molecules interacted with the TLR5 flagellin recognition sites with a high binding affinity. We conclude that acemannan induces IL-6/-8 expression, and p50/DNA binding in gingival fibroblasts, at least partly, via a TLR5/NF-κB-dependent signaling pathway. Furthermore, acemannan selectively binds with TLR5 ectodomain flagellin recognition sites.

Toll-like receptors (TLRs) signalling and expression pattern

Toll is a Drosophila gene essential for ontogenesis and antimicrobial resistance. Several homologues of Toll have been identified and cloned in vertebrates, namely Toll-like receptors (TLRs). TLRs are structurally characterized by a cytoplasmic Toll/interleukin-1R (TIR) domain and by extracellular leucine rich repeats. TLRs characterized so far activate the MyD88/IRAK signalling cascade which activates NF-κB transcription factor. Genetic, gene transfer, and dominant negative approaches have involved TLR family members (TLR2 and TLR4) in distinct bacterial components for recognition and signalling. However, very little information is available regarding other TLRs. Here we propose to classify TLRs based on their expression pattern, in ubiquitous (TLR1), restricted (TLR2, 4, 5) and specific (TLR3) TLRs. Differential expression and regulation as well as distinct, though overlapping, ligand recognition patterns may underlie the existence of a such a large, seemingly redundant, TLR family.

Co-operative induction of pro-inflammatory signaling by Toll-like receptors

Toll-like receptors (TLRs) mediate detection of a broad range of pathogens and pathogen-derived products including LPS, peptidoglycan, bacterial lipopeptides, and lipoteichoic acid. Recent evidence indicates that the broad specificity of TLRs may be a consequence of the interactions between different TLRs. In this report, we demonstrate that while a constitutively active TLR4 homodimer can induce the production of pro-inflammatory cytokines, homodimers of TLR2 and TLR6 cannot. However, when co-expressed in the same cell, constitutively active TLR2 and TLR6 strongly induce cytokine production, indicating that these TLRs require partners to productively signal. Since TLR4 signals as a homodimer, while TLR2 and TLR6 do not, it is clear that, despite the conservation of their cytoplasmic signaling domains, the mechanisms by which they initiate signaling are different. We have localized the region of TLR4 that mediates its ability to signal as a homodimer to the membrane-proximal half of the cytoplasmic tail of the receptor.

A Standardized Chemically Modified Curcuma longa Extract Modulates IRAK-MAPK Signaling in Inflammation and Potentiates Cytotoxicity

The TLR/IL-1R pathway is a critical signaling module that is misregulated in pathologies like inflammation and cancer. Extracts from turmeric (Curcuma longa L.) enriched in curcumin and carbonyls like turmerones have been shown to exert potent anti-inflammatory effects. The present study evaluated the anti-inflammatory activity, cytotoxic effect and the underlying mechanism of a novel chemically modified, non-carbonyl compound enriched Curcuma longa L. (C. longa) extract (CMCE). CMCE (1 or 10 μg/mL; 14 h) significantly decreased LPS (50-100 ng/mL) induced TNF-α and IL-1β production in THP-1 cells, human, and mouse whole blood as measured by ELISA. LPS-induced IRAK1, MAPK activation, TLR4 expression, TLR4-MyD88 interaction, and IκBα degradation were significantly reduced in CMCE pre-treated THP-1 cells as assessed by Western blotting. CMCE (30, 100, and 300 mg/kg; 10 days p.o.) pre-treated and LPS (10 mg/kg) challenged Swiss mice exhibited attenuated plasma TNF-α, IL-1β, nitrite, aortic iNOS expression, and vascular dysfunction. In a PI permeability assay, cell lines derived from acute myeloid leukemia were most sensitive to the cytotoxic effects of CMCE. Analysis of Sub-G1 phase, Annexin V-PI positivity, loss of mitochondrial membrane potential, increased caspase-3, and PARP-1 activation confirmed CMCE induced apoptosis in HL-60 cells. IRAK inhibition also sensitized HL-60 cells to CMCE induced cytotoxicity. The present study defines the mechanism underlying the action of CMCE and suggests a therapeutic potential for its use in sepsis and leukemia.

The LXR ligand GW3965 inhibits Newcastle disease virus infection by affecting cholesterol homeostasis

Newcastle disease (ND) is a contagious disease that affects most species of birds. Its causative pathogen, Newcastle disease virus (NDV), also exhibits considerable oncolytic activity against mammalian cancers. A better understanding of the pathogenesis of NDV will help us design efficient vaccines and novel anticancer strategies. GW3965, a widely used synthetic ligand of liver X receptor (LXR), induces the expression of LXRs and its downstream genes, including ATP-binding cassette transporter A1 (ABCA1). ABCA1 regulates cellular cholesterol homeostasis. Here, we found that GW3965 inhibited NDV infection in DF-1 cells. It also inhibited NF-κB activation and reduced the upregulation of proinflammatory cytokines induced by the infection. Further studies showed that GW3965 exerted its inhibitory effects on virus entry and replication. NDV infection increased the mRNA levels of several lipogenic genes but decreased the ABCA1 mRNA level. Overexpression of ABCA1 inhibited NDV infection and reduced the cholesterol content in DF-1 cells, but when the cholesterol was replenished, NDV infection was restored. GW3965 treatment prevented cholesterol accumulation in the perinuclear area of the infected cells. In summary, our studies suggest that GW3965 inhibits NDV infection, probably by affecting cholesterol homeostasis.

TRIF-dependent TLR signaling, its functions in host defense and inflammation, and its potential as a therapeutic target

Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF)-dependent signaling is required for TLR-mediated production of type-I IFN and several other proinflammatory mediators. Various pathogens target the signaling molecules and transcriptional regulators acting in the TRIF pathway, thus demonstrating the importance of this pathway in host defense. Indeed, the TRIF pathway contributes to control of both viral and bacterial pathogens through promotion of inflammatory mediators and activation of antimicrobial responses. TRIF signaling also has both protective and pathologic roles in several chronic inflammatory disease conditions, as well as an essential function in wound-repair processes. Here, we review our current understanding of the regulatory mechanisms that control TRIF-dependent TLR signaling, the role of the TRIF pathway in different infectious and noninfectious pathologic states, and the potential for manipulating TRIF-dependent TLR signaling for therapeutic benefit.

Mechanism of Action of Probiotic Bacteria on Intestinal and Systemic Immunities and Antigen-Presenting Cells

Immunomodulation has been shown to be one of the major functions of probiotic bacteria. This review is presented to provide detailed information on the immunomodulatory properties of probiotics in various animal models and clinical practices. Probiotics can regulate helper T (Th) responses and release of cytokines in a strain-specific manner. For example, Lactobacillus rhamnosus GG can induce beneficial Th1 immunomodulatory effect in infants with cow's milk allergy and relieve intestinal inflammation in atopic children by promoting IL-10 generation. Mechanism of action of probiotics on antigen-presenting cells at gastrointestinal tract is also postulated in this review. Probiotic bacterial cells and their soluble factors may activate dendritic cells, macrophages, and to certain extent monocytes via toll-like-receptor recognition and may further provoke specific Th responses. They are speculated to elicit immunomodulatory effects on intestinal and systemic immunities.

Structure and function of Toll/interleukin-1 receptor/resistance protein (TIR) domains

The Toll/interleukin-1 receptor/resistance protein (TIR) domain is a protein-protein interaction domain consisting of 125-200 residues, widely distributed in animals, plants and bacteria but absent from fungi, archea and viruses. In plants and animals, these domains are found in proteins with functions in innate immune pathways, while in bacteria, some TIR domain-containing proteins interfere with the innate immune pathways in the host. TIR domains function as protein scaffolds, mostly involving self-association and homotypic interactions with other TIR domains. In the last 15 years, the three-dimensional structures of TIR domains from several mammalian, plant and bacterial proteins have been reported. These structures, jointly with functional data including the identification of interacting proteins, have started to provide insight into the molecular basis of the assembly of animal and plant immune signaling complexes, and for host immunosuppression by bacterial pathogens. This review focuses on the current knowledge of the structures of the TIR domains and how the structure relates to function.

Angiotensin II-induced hypertensive renal inflammation is mediated through HMGB1-TLR4 signaling in rat tubulo-epithelial cells

BACKGROUND AND PURPOSE

Angiotensin II is a vaso-constrictive peptide that regulates blood pressure homeostasis. Even though the inflammatory effects of AngII in renal pathophysiology have been studied, there still exists a paucity of data with regard to the mechanism of action of AngII-mediated kidney injury. The objective of this study was to elucidate the mechanistic role of HMGB1-TLR4 signaling in AngII-induced inflammation in the kidney.

EXPERIMENTAL APPROACH

Rat tubular epithelial cells (NRK52E) were treated with AngII over a preset time-course. In another set of experiments, HMGB1 was neutralized and TLR4 was knocked down using small interfering RNA targeting TLR4. Cell extracts were subjected to RT-PCR, immunoblotting, flow cytometry, and ELISA.

KEY RESULTS

AngII-induced inflammation in NRK52E cells increased gene and protein expression of TLR4, HMGB1 and key proinflammatory cytokines (TNFα and IL1β). Pretreatment with Losartan (an AT1 receptor blocker) attenuated the AngII-induced expression of TLR4 and inflammatory cytokines. TLR4 silencing was used to elucidate the specific role played by TLR4 in AngII-induced inflammation. TLR4siRNA treatment in these cells significantly decreased the AngII-induced inflammatory effect. Consistent observations were made when the Ang II treated cells were pretreated with anti-HMGB1. Downstream activation of NFκB and rate of generation of ROS was also decreased on gene silencing of TLR4 and exposure to anti-HMGB1.

CONCLUSIONS AND IMPLICATIONS

These results indicate a key role for HMGB1-TLR4 signaling in AngII-mediated inflammation in the renal epithelial cells. Our data also reveal that AngII-induced effects could be alleviated by HMGB1-TLR4 inhibition, suggesting this pathway as a potential therapeutic target for hypertensive renal dysfunctions.

Association Between TRAF6 Gene Polymorphisms and Susceptibility of Ischemic Stroke in Southern Chinese Han Population

The tumor necrosis factor receptor-associated factor 6 (TRAF6) gene encodes a protein that acts downstream of the Toll-like receptor (TLR) pathway. TLRs activate inflammatory cascades and mediate inflammatory injury after cerebral ischemia. However, the role of TFAR6 gene polymorphisms in ischemic stroke (IS) remains unknown. This study aims to investigate the associations of TRAF6 gene polymorphisms with susceptibility to IS and IS-related quantitative traits in Southern Chinese Han population. A total of 816 IS cases and 816 age- and gender-matched controls were included. Two variants of the TRAF6 gene (rs5030411 and rs5030416) were genotyped using the Sequenom MassARRAY iPLEX platform. Our study showed that rs5030416 was significantly associated with increased susceptibility to IS in the additive model [ORadj 1.25(1.04-1.51), P adj = 0.019, P Bc = 0.038] and dominant model [ORadj 1.23(1.04-1.60), P adj = 0.021, P Bc = 0.042] after adjusting by age and sex and applying a Bonferroni correction. No significant association was found between rs5030411 and IS susceptibility (all P > 0.05). The haplotype rs5030416 (allele C)-rs5030411 (allele C) was significantly associated with IS susceptibility (P adj = 0.015). Moreover, a significant association of rs5030411 with TC levels in IS patients under the additive model [β 0.16(0.01-0.30), P adj = 0.034] and recessive model [β 0.45(0.12-0.78), P adj = 0.007] was observed after adjustment by age and sex. This association remained statistically significant under the recessive model (P Bc = 0.042) after Bonferroni correction. Our results suggest that TRAF6 gene polymorphisms may be involved in the pathogenesis of IS.

Identification, expression pattern and functional characterization of As-MyD88 in bacteria challenge and during different developmental stages of Artemia sinica

Myeloid differentiation factor 88 (MYD88), a key adapter protein in Toll-like receptor signaling, affects the immune response and the formation of the dorsal-ventral axis. Here, the 1555bp full-length cDNA of MyD88 from Artemia sinica (As-MyD88) was obtained. Molecular characterization revealed that the sequence includes an 1182bp open reading frame encoding a predicted protein of 393 amino acids. The predicted protein contains a death domain in the N-terminus, and box1 and 2 motifs of the TIR domain in the C-terminus. Real-time quantitative PCR, Western blotting and immunohistochemistry were used to determine the expression level, protein production and location of As-MYD88 during embryonic development and bacterial challenge. The highest expression level during embryonic development was at the 0h and 5h stages of A. sinica. As-MYD88 was remarkably upregulated after bacterial challenge. Our results suggested that As-MYD88 plays a vital role in response to bacterial challenge, and during post-diapause embryonic development of A. sinica.