Toll-like Receptor Research Articles

Differential Adjuvant Activity by Flagellins from Escherichia coli, Salmonella enterica Serotype Typhimurium, and Pseudomonas aeruginosa

(1) Background: The adjuvant properties of flagellin from various bacterial species have been extensively studied; however, a systematic comparison of the immunoadjuvant effects of flagellins from different bacterial species is lacking. This study aims to analyze the amino acid sequences and structural features of flagellins from Escherichia coli (FliCE.C), Salmonella enterica serotype Typhimurium (FliCS.T), and Pseudomonas aeruginosa (FliCP.A), and to evaluate their adjuvant activities in terms of Toll-like receptor 5 (TLR5) activation, antibody production, and cytokine responses in a murine model. (2) Methods: Bioinformatics analysis was conducted to compare the amino acid sequences and structural domains (D0, D1, D2, and D3) of flagellins from the three bacterial species. PyMol atomic models were used to confirm structural differences. Toll-like receptor 5 (TLR5) activation assays were performed to measure IL-8 and TNF-α production in vitro. The IgG antibody titers against the model antigen FaeG and cytokine responses, including IL-4 and TNF-α secretion were evaluated in a murine model. (3) Results: Bioinformatics analysis revealed that the D0 and D1 domains are highly conserved, whereas the D2 and D3 domains exhibit significant variability across the three species. Structural analysis via PyMol confirmed these differences, particularly in the D2 and D3 domains. TLR5 activation assays showed that FliCS.T and FliCP.A induced higher levels of IL-8 and TNF-α production compared to FliCE.C, indicating species-specific variations in TLR5 activation. In the murine model, FliCS.T as an adjuvant produced higher antibody titers against FaeG and increased IL-4 secretion in splenocytes compared to FliCE.C and FliCP.A. FliCP.A induced higher TNF-α expression than FliCS.T and FliCE.C, suggesting FliCS.T and FliCP.A are more effective at inducing T-cell responses. (4) Conclusions: This study highlights the potential of FliCS.T and FliCP.A as potent vaccine adjuvants. The results provide insights into the structure–function relationships of these flagellins and support their application in enhancing immune responses against diverse pathogens.

Inhibiting the cholesterol storage enzyme ACAT1/SOAT1 in aging Apolipoprotein E4 mice alter their brains inflammatory profiles.

Aging and Apolipoprotein E4 (APOE4) are the two most significant risk factors for late-onset Alzheimer's disease (LOAD). Compared to APOE3, APOE4 disrupts cholesterol homeostasis, increases cholesteryl esters (CEs), and exacerbates neuroinflammation in brain cells including microglia. Targeting CEs and neuroinflammation could be a novel strategy to ameliorate APOE4 dependent phenotypes. Toll-like receptor 4 (TLR4) is a key player in inflammation, its regulation is associated with cholesterol content of lipid rafts in cell membranes. We previously demonstrated that in normal microglia expressing APOE3, inhibiting the cholesterol storage enzyme acylCoA:cholesterol acyltransferase 1 (ACAT1/SOAT1) reduces CEs, dampened neuroinflammation via modulating the fate of TLR4. We also showed that treating myelin debris-loaded normal microglia with ACAT inhibitor F12511 reduced cellular CEs and activated ABC transporter 1 (ABCA1) for cholesterol efflux. In this study, we found that treating primary microglia expressing APOE4 with F12511 also reduces CEs, activated ABCA1, and dampened LPS dependent NFkB activation. In vivo, a two-week injections of nanoparticle F12511, which consists of DSPE-PEG 2000 , phosphatidylcholine, and F12511, to aged female APOE4 mice reduced TLR4 protein content and decreased proinflammatory cytokines including IL-1β in APOE4 mice brains. Overall, our work suggests nanoparticle F12511 is a novel agent to ameliorate LOAD.

CMTM3 regulates neutrophil activation and aggravates sepsis through TLR4 signaling.

Regulation of neutrophil activation plays a significant role in managing sepsis. CKLF-like MARVEL transmembrane domain containing (CMTM)3 is a membrane protein involved in immune response. Here, we find that CMTM3 expression is elevated in sepsis and plays a crucial role in mediating the imbalance of neutrophil migration. Cmtm3 knockout improves the survival rate of septic mice, mitigate inflammatory responses, and ameliorate organ damage. Mechanistically, the deletion of Cmtm3 reduced the expression of Toll-like receptor 4 (TLR4) on neutrophils, leading to a decrease in the expression of C-X-C motif chemokine receptor 2 (CXCR2) on the cell membrane. This resulted in a reduced migration of neutrophils from the bone marrow to the bloodstream, thereby attenuating their recruitment to vital organs. Our findings suggest that targeting CMTM3 holds promise as a therapeutic approach to ameliorate the dysregulation of neutrophil migration and multi-organ damage associated with sepsis.

Heat-Killed Lactobacillus paracasei SMB092 Reduces Halitosis by Stimulating the Expression of β-Defensins in Oral Keratinocytes

The purpose of this study is to evaluate Lactobacillus paracasei SMB092 as a prophylactic agent for oral pathogens. We examined the physical interaction of SMB092 with a host by identifying the presence of mucus-binding (MuB) protein domains and the capacity of the mucin binding. We determined the role of heat-killed SMB092 in host oral immunity by quantifying the mRNA levels of β-defensins (BDs), Toll-like receptors (TLRs), and their cofactors (CD14/CD36) in normal human oral keratinocytes (HOK-16B cells). To assess the clinically relevant oral health effects of heat-killed SMB092, the growth of Porphyromonas (P.) gingivalis and the production of a volatile sulfur compound (H2S) were also measured in the filtered condition media (FCM) obtained from its cultures with HOK-16B cells. SMB092 possessed 14 putative MuB protein domains and was attached to mucin. Significant amounts of hBD1/2 and TLR2/6 were expressed in heat-killed SMB092-treated HOK-16B cells. The specific neutralization of TLR2 attenuated the expression of hBD1/2 and CD14/CD36. The FCM inhibited the growth of P. gingivalis and the production of H2S. Our data indicate that heat-killed SMB092 may contribute to a healthy oral microbiome as an immune stimulant in the production of BDs via the activation of the TLR2/6 signaling pathway.

A TLR7 Agonist Conjugated to a Nanofibrous Peptide Hydrogel as a Potent Vaccine Adjuvant.

Toll-like receptors (TLRs) recognize pathogen- and damage-associated molecular patterns and, in turn, trigger the release of cytokines and other immunostimulatory molecules. As a result, TLR agonists are increasingly being investigated as vaccine adjuvants. Many of these agonists are small molecules that quickly diffuse away from the vaccination site, limiting their co-localization with antigens and, thus, their effect. Here, the small-molecule TLR7 agonist 1V209 is conjugated to a positively-charged multidomain peptide (MDP) hydrogel, K2, which was previously shown to act as an adjuvant promoting humoral immunity. Mixing the 1V209-conjugated K2 50:50 with the unfunctionalized K2 produces hydrogels that retain the shear-thinning and self-healing physical properties of the original MDP while improving the solubility of 1V209 more than 200-fold compared to the unconjugated molecule. When co-delivered with ovalbumin as a model antigen, 1V209-functionalized K2 produces a robust Th2 immune response and an antigen-specific Th1 immune response superior to alum, a widely used vaccine adjuvant. Together, these results suggest that K2 MDP hydrogels functionalized with 1V209 are a promising adjuvant for vaccines against infectious diseases, especially those benefiting from a combined Th1 and Th2 immune response.

Advances in the study of artemisinin and its derivatives for the treatment of rheumatic skeletal disorders, autoimmune inflammatory diseases, and autoimmune disorders: a comprehensive review

Artemisinin and its derivatives are widely recognized as first-line treatments for malaria worldwide. Recent studies have demonstrated that artemisinin-based antimalarial drugs, such as artesunate, dihydroartemisinin, and artemether, not only possess excellent antimalarial properties but also exhibit antitumor, antifungal, and immunomodulatory effects. Researchers globally have synthesized artemisinin derivatives like SM735, SM905, and SM934, which offer advantages such as low toxicity, high bioavailability, and potential immunosuppressive properties. These compounds induce immunosuppression by inhibiting the activation of pathogenic T cells, suppressing B cell activation and antibody production, and enhancing the differentiation of regulatory T cells. This review summarized the mechanisms by which artemisinin and its analogs modulate excessive inflammation and immune responses in rheumatic and skeletal diseases, autoimmune inflammatory diseases, and autoimmune disorders, through pathways including TNF, Toll-like receptors, IL-6, RANKL, MAPK, PI3K/AKT/mTOR, JAK/STAT, and NRF2/GPX4. Notably, in the context of the NF-κB pathway, artemisinin not only inhibits NF-κB expression by disrupting upstream cascades and/or directly binding to NF-κB but also downregulates multiple downstream genes controlled by NF-κB, including inflammatory chemokines and their receptors. These downstream targets regulate various immune cell functions, apoptosis, proliferation, signal transduction, and antioxidant responses, ultimately intervening in systemic autoimmune diseases and autoimmune responses in organs such as the kidneys, nervous system, skin, liver, and biliary system by modulating immune dysregulation and inflammatory responses. Ongoing multicenter randomized clinical trials are investigating the effects of these compounds on rheumatic, inflammatory, and autoimmune diseases, with the aim of translating promising preclinical data into clinical applications.

Immunostimulation Signaling via Toll-like Receptor 2 Activation: A Molecular Mechanism of Lactococcus lactis OTG1204 In Vitro and In Vivo

Introduction: The immune system’s defense against pathogens involves innate and adaptive responses, crucial in maintaining overall health. Immunosuppressed states render individuals more susceptible to potential diseases, indicating the need for effective strategies to bolster immune functions. Objectives: Although the immunostimulatory effects of various probiotics have been studied, the specific effects and molecular mechanisms of Lactococcus lactis OTG1204 (OTG1204) remain unknown. In this study, the aim was to investigate the molecular mechanisms of OTG1204 in RAW 264.7 macrophages, the key effector cells of the innate immune system involved in host defense and inflammatory responses. Additionally, in this study, the effects of OTG1204 on cyclophosphamide (CTX)-induced immunosuppression states were investigated, thereby demonstrating its potential as an immune stimulant. Methods: To assess the macrophage activation ability and underlying mechanisms of OTG1204, RAW 264.7 cells were utilized with transfection, enzyme-linked immunosorbent assay, and quantitative real-time PCR analyses. Furthermore, to evaluate the immunostimulatory effects under immunosuppressed conditions, CTX-induced immunosuppression mice model was employed, and analyses were performed using hematoxylin and eosin staining, flow cytometry, and microbiota examination. Results: OTG1204 activated RAW 264.7 macrophages, leading to increased production of nitric oxide, prostaglandin E2, and cytokines. This immune activation was mediated through the upregulation of toll-like receptor 2, which subsequently activated the nuclear factor-κB (NF-kB) and mitogen-activated protein kinase (MAPK)/activator protein 1 (AP-1) pathways, thereby stimulating the immune response. In CTX-treated mice, OTG1204 recovered body weight, spleen, and mesenteric lymph node indices, and natural killer cell activity. It re-established populations of innate and adaptive immune cells and activated T cells to secrete cytokines. We also examined the gut barrier integrity and microbiota composition to assess OTG1204’s impact on intestinal health, as these factors play a significant role in immune enhancement. OTG1204 enhanced gut barrier integrity by upregulating mucin 2 and tight junction proteins and modulated the gut microbiota by restoring the Firmicutes/Bacteroidetes balance and reducing the abundance of Actinobacteria and Tenericutes. Conclusion: These results suggest that OTG1204 may serve as an effective probiotic for immune enhancement and gut health management by targeting the NF-κB and MAPK/AP-1 pathways, with minimal side effects.

The paradigm of possibilities leading to the formation of autoimmune and infectious phenotypes of common variable immune deficiency

The term variable in the definition of CVID is associated with the heterogeneity of the genetic nature and clinical manifestation of this variant of PI. Deciphering of the mechanisms or identifying biomarkers of clinical heterogeneity may be important in the timely diagnosis and prognosis of the course of CVID. The purpose of the study was to identify distinctive features in the parameters of the innate and adaptive immune response of the patients with infectious and autoimmune manifestations of CVID in remission and clinical manifestation. Fifteen patients, 11 women and 4 men with an average age 39.7±11.7 years were examined, and they were divided into two subgroups depending on clinical verification: infectious phenotype (10 people) and autoimmune phenotype (5 people). In the absence of clinical signs of activation of autoimmune pathology or exacerbation of chronic infectious processes, peripheral blood monocytes became the application point of distinctive values. An increase in the number of TLR9-expressing monocytes has been shown in patients with autoimmune clinical verification of CVID. The differences in the parameters of the immune status of patients conducted during the period of clinical manifestation consisted of a decrease in the relative content and absolute number of T regulatory lymphocytes, and an increase in the number of monocytes containing TLR9, TLR2 and HLA-DR in patients with an autoimmune phenotype relative to the subgroup with infectious manifestation. The data obtained reflect the involvement of the immunoregulatory potential of the immune system in the clinical manifestation of primary immunodeficiency, even under the conditions of pathogenetic substitution therapy. The evidence of the stated position is a decrease in immunosuppression in autoimmune manifestation due to a decrease in the number of peripheral T-regulatory cells and a smaller proportion of monocyte cells belonging to the M2 suppressive category. Attention is also drawn to the increased potential of primary response to patterns of various nature in autoimmune manifestation due to an increase in the number of monocytes expressing Toll-like receptors of various specificity. The presented results can be proposed as a diagnostic and prognostic indicator of the difference in clinical phenotypes of CVID.

Ilex asprella-derived polysaccharide activates macrophage via TLR4-mediated NF-κB and MAPK signaling pathways

Ilex asprella, a valued herb in China, is recognized for its medicinal and dietary benefits, yet its active components and mechanisms of action have been largely unknown. This study focused on the polysaccharide extracted from Ilex asprella (IAP) and to investigate its structural characteristics and immunomodulatory effects. The results indicated IAP had a molecular weight of 3324 Da and was mainly composed of arabinose, galactose, glucose, and mannose. In vitro study showed 10, 50, and 100 μg/mL of IAP significantly increased the mRNA expression of inducible nitric-oxide synthase, cyclooxygenase-2, reactive oxygen, and cytokines in RAW264.7 macrophages. According to the results, IAP also facilitated the nucleus translocation of NF-κB p65 and activated the phosphorylation of p38, JNK, and ERK, revealing IAP activated RAW264.7 cells via NF-κB and MAPK signaling pathways. Furthermore, the results of membranes receptor inhibitor administration suggested toll-like receptor 4 might be the action target of IAP.

Gestational Diabetes Mellitus-Induced Inflammation in the Placenta via IL-1β and Toll-like Receptor Pathways

Gestational diabetes mellitus is characterised by an insufficient insulin response to hyperglycaemia and the development of insulin resistance. This state has adverse effects on the health outcomes of the mother and child. Existing hyperglycaemia triggers a state of inflammation that involves several tissues, including the placenta. In this study, we analysed the putative pathomechanism of GDM, with special emphasis on the role of chronic, sterile, pro-inflammatory pathways. The expression and regulation of the elements of IL-1β and Toll-like receptor (TLR) pathways in GDM maternal blood plasma, healthy placental explants and a choriocarcinoma cell line (BeWo cell line) stimulated with pro-inflammatory factors was evaluated. Our results indicate elevated expression of the IL-1β and TLR pathways in GDM patients. After stimulation with IL-1β or LPS, the placental explants and BeWo cell line showed increased production of pro-inflammatory IL-6, TNFa and IL-1β together with increased expression of the elements of the signalling pathways. The application of selected inhibitors of NF-ĸB, MAPK and recombinant interleukin 1 receptor antagonist (IL1RA) proved the key involvement of the IL-1β pathway and TLRs in the pathogenesis of GDM. Our results show the possible existence of loops of autocrine stimulation and a possible inflammatory pathomechanism in placentas affected by GDM.

Hematobiochemical Changes, Immunological Response and Immune Gene Expression in Nile Tilapia (Oreochrom niloticus) Experimentally Infected with Shewanella putrefaciens

Background: In this work, hematobiochemical changes, immunological responses, and histopathological changes in Nile tilapia (Oreochromis niloticus) experimentally infected with Shewanella putrefaciens were studied. Methods: O. niloticus was experimentally infected with S. putrefaciens (4SK/SRLFDA/19) at a concentration of 1.508×106CFU/ml per fish. Gross symptoms, namely hemorrhage on the body surface, skin discoloration, slow or nervous behavior, shallow necrotizing ulcers on the skin, fin erosions and abdominal distension were observed 5 to 6 days after infection. Fish were anesthetized and blood samples were collected at 0, 2, 4, 7, 10, 14, 20 and 27 days after the experimental infection to assess the hematobiochemical and immunological responses. For haematobiochemical responses, tests that included hemoglobin (Hb), leukocyte count (Lc), erythrocyte, hematocrite (Ht), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), cholesterol (CHO), glucose (GLU) and triglyceride were assessed. Result: Values of hematocrit, hemoglobin, albumin, globulin, erythrocyte, MCHC, cholesterol and triglyceride were significantly (p less than 0.05) decreased. Lc, MCV, MCH, and glucose values were significantly (p less than 0.05) increased. Respiratory burst activity (RBA) and serum total protein values were significantly (p less than 0.05) decreased. Relative expression of immune gene toll like receptor 4 (TLR4), stress genes heat shock proteins 70, 90 (HSP70, HSP90), oxidative stress gene glutathione S-transferases (GST) and inflammatory gene interleukin 6 (IL6) was significantly higher in experimentally infected fishes compared to control.

Preventive effects of matrine on LPS-induced inflammation in RAW 264.7 cells and intestinal damage in mice through the TLR4/NF-κB/MAPK pathway

BackgroundMatrine is a tetracyclic quinolizidine alkaloid with diverse bioactive properties, including anti-inflammatory and neuroprotective properties. However, the underlying anti-inflammatory mechanisms remain unclear. PurposeThis study aimed to explore how matrine reduces Lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 cells and to assess its protective effects against LPS-induced intestinal damage. MethodsThe effect of matrine on cell viability was assessed using the cell counting kit-8 (CCK-8) assay. Additionally, its impact on inflammatory cytokines and macrophage polarization was assessed using enzyme-linked immunosorbent assay (ELISA), flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR) analyses. The effects on intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), nitric oxide (NO) production, and oxidative stress were evaluated using 2′,7′-dichlorodihydrofluorescein diacetate staining and JC-1 and Griess assays. Immunofluorescence staining was used to observe the translocation of the NF-κB p65 subunit. Western blotting (WB) and qRT-PCR were employed to analyze the expression levels of proteins related to the toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB)/mitogen-activated protein kinase (MAPK) pathway. An LPS-induced mouse model was established to study the intestinal inflammation and barrier injury. Mouse feces characteristics, colon length, and disease activity index (DAI) were recorded. Hematoxylin-eosin (H&E) and alcian blue/periodic acid schiff (AB/PAS) staining were used to observe morphological changes and barrier damage in the duodenum, jejunum, ileum, and colon and to measure villus length, crypt depth, goblet cell count, and positive areas in the duodenum, jejunum, and ileum. The content of short-chain fatty acids (SCFAs) in the colon was determined using gas chromatography (GC). ResultsMatrine inhibited LPS-induced inflammatory cytokine levels, suppressed macrophage M1 polarization, and promoted M2 macrophage polarization. Matrine reduced LPS-induced increases in ROS and NO levels and regulates oxidative stress. Additionally, matrine inhibited the nuclear translocation of the NF-κB p65 subunit and exerted anti-inflammatory effects by suppressing the activation of the TLR4/NF-κB/MAPK pathway. In vivo experiments indicated that matrine significantly alleviated LPS-induced diarrhea, increased DAI, and shortened the colon. Matrine reduced the production of the pro-inflammatory cytokine interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α and the pro-inflammatory mediator NO in mouse intestinal tissues while promoting the content of the anti-inflammatory cytokine IL-10. Furthermore, it improved intestinal tissue structure and alleviated LPS-induced intestinal barrier damage. Finally, matrine increased the SCFA levels in the intestine. ConclusionMatrine exerted its anti-inflammatory effects and protects against intestinal injury through the TLR4/NF-κB/MAPK signaling pathway.

Diallyl Disulfide Mitigates Cadmium Hepatotoxicity by Attenuating Oxidative Stress and TLR-4/NF-κB Signaling and Upregulating PPARγ.

Heavy metals can cause serious health problems that affect different organs. Cadmium (Cd) is an environmental contaminant known for its toxicological consequences on different organs. Hepatotoxicity is a serious effect of exposure to Cd with oxidative stress (OS) and inflammation playing a central role. Diallyl disulfide (DADS), an organo-sulfur compound found in garlic, is known for its cytoprotective and antioxidant effects. In this study, the effect of DADS on Cd-induced inflammation, oxidative stress and liver injury was investigated. DADS was supplemented for 14 days via oral gavage, and a single intraperitoneal dose of Cd (1.2 mg/kg body weight) was administered to rats on day 7. Blood and liver samples were collected at the end of the experiment for analyses. Cd administration resulted in remarkable hepatic dysfunction, degenerative changes, necrosis, infiltration of inflammatory cells, collagen deposition and other histopathological alterations. Cd increased liver malondialdehyde (MDA) and nitric oxide (NO) (p < 0.001), upregulated toll-like receptor (TLR)-4, nuclear factor-kappaB (NF-κB), pro-inflammatory mediators, and caspase-3 (p < 0.001) whereas decreased glutathione (GSH) and antioxidant enzymes (p < 0.001). Cd downregulated peroxisome proliferator activated receptor gamma (PPARγ), a transcription factor involved in inflammation and OS suppression (p < 0.001). DADS ameliorated liver injury and tissue alterations, attenuated OS and apoptosis, suppressed TLR-4/NF-κB signaling, and enhanced antioxidants. In addition, DADS upregulated PPARγ in the liver of Cd-administered rats. DADS is effective against Cd-induced hepatotoxicity and its beneficial effects are linked to suppression of inflammation, OS and apoptosis and upregulation of PPARγ. DADS could be valuable to protect the liver in individuals at risk of Cd exposure, pending further studies to elucidate other underlying mechanism(s).

T lymphocyte-dependent IL-10 down-regulates a cytokine storm driven by Toxoplasma gondii GRA24.

As a model organism in the study of immunity to infection, Toxoplasma gondii has been instrumental in establishing key principles of host anti-microbial defense and its regulation. Here, we employed an attenuated uracil auxotroph strain of Type I Toxoplasma designated OMP to further untangle the early immune response to this parasitic pathogen. Experiments using αβ T cell-deficient Tcrb-/- mice unexpectedly revealed that an intact αβ T lymphocyte compartment was essential to survive infection with OMP. Subsequent antibody depletion and knockout mouse experiments demonstrated contributions from CD4+ T cells and most predominantly CD8+ T cells in resistance. Using transgenic knockout mice, we found only a partial requirement for IFN-γ and a lack of requirement for Toll-like receptor (TLR) adaptor MyD88 in resistance. In contrast to other studies on Toxoplasma, the ability to survive OMP infection did not require IL-12p40. Surprisingly, T cell-dependent IL-10 was found to be critical for survival, and deficiency of this cytokine triggered an abnormally high systemic inflammatory response. We also found that parasite molecule GRA24, a dense granule protein that triggers TLR-independent IL-12 production, acts as a virulence factor contributing to death of OMP-infected Tcrb-/- and IL-10-/- mice. Furthermore, resistance against OMP was restored in Tcrb-/- mice via monoclonal depletion of IL-12p40, suggesting that GRA24-induced IL-12 underlies the fatal immunopathology observed. Collectively, our studies provide insight into a novel and rapidly arising T lymphocyte-dependent anti-inflammatory response to T. gondii which operates independently of MyD88 and IL-12 and that depends on the function of parasite-dense granule protein GRA24.IMPORTANCEAs a model infectious microbe and an important human pathogen, the apicomplexan Toxoplasma gondii has provided many important insights into innate and adaptive immunity to infection. We show here that a low virulence uracil auxotrophic Toxoplasma strain emerges as a virulent parasite in the absence of an intact T cell compartment. Both CD4+ and CD8+ T lymphocytes are required for optimal protection, in line with previous findings in other models of Toxoplasma infection. Nevertheless, several novel aspects of the response were identified in our study. Protection occurs independently of IL-12 and MyD88 and only partially requires IFN-γ. This is noteworthy particularly because the cytokines IL-12 and IFN-γ have previously been regarded as essential for protective immunity to T. gondii. Instead, we identified the anti-inflammatory effects of T cell-dependent IL-10 as the critical factor enabling host survival. The parasite dense granule protein GRA24, a host-directed mitogen-activated protein kinase activator, was identified as a major virulence factor in T cell-deficient hosts. Collectively, our results provide new and unexpected insights into host resistance to Toxoplasma.

Integration of metabolomics and transcriptomics reveals the toxicological mechanism of deltamethrin exposure in Chinese mitten crab Eriocheir sinensis

This study investigated the toxicological mechanism of deltamethrin on Chinese mitten crab Eriocheir sinensis juveniles in fresh water. We first conducted an acute toxicity test, followed by laboratory methods to detect changes in immune-related indices in terms of antioxidant enzyme markers, lipid metabolism-related genes, and autophagy-related and apoptosis genes. The acute toxicity (96-h LC50) of deltamethrin to E. sinensis was 7.195 μg/L. After 48 h of exposure, serum showed elevated immune-related indices (P < 0.05) for alkaline phosphatase (AKP), acid phosphatase (ACP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), complement components C3 and C4, and the key pro-inflammatory cytokines interleukin-6, interleukin-1β, and tumor necrosis factor alpha (TNF-α). In hepatopancreas at 48 h, indicators related to the antioxidant system, namely superoxide dismutase (SOD) and glutathione (GSH), were significantly elevated, whereas nitric oxide and total antioxidant capacity (T-AOC) were decreased (P < 0.05). In contrast, lipid metabolism indices for triglyceride (TG), total cholesterol (TC), and malondialdehyde (MDA) were increased (P < 0.05). Transcriptomics and metabolomics revealed that exposure to deltamethrin disrupted the lipid metabolic process in the hepatopancreas mainly by altering fatty acid synthesis, amino acid metabolism, immune signaling, and autophagy activation, while the exposure increased the content of phospholipids and cholesterol but decreased the levels of amino acids and palmitoleic acid. Quantitative genetics revealed significantly aberrantly expressed (P < 0.05) lipid metabolism-related genes, including acc1, fasn, scd1, and pnpla2, all key genes involved in lipid accumulation. Deltamethrin exposure also significantly altered (P < 0.05) gene expression levels for Toll-like receptor (tlr), myeloid differentiation factor 88 (myd88), crustin1, anti-lipopolysaccharide factor isoform 3 (alf3), tumor necrosis factor alpha (tnf-α), and NF-κB transcription factor relish. Furthermore, deltamethrin activated the toll-like receptor/major myeloid differentiation response gene 88/nuclear factor kappa-light-chain-enhancer of activated B cells (TLR/MyD88/NF-kB) signaling pathway, which activates a nonspecific immune response in E. sinensis. Additionally, carnitine palmitoyltransferase 1 A (cpt1a), cytochrome c (cyt-c), adenosine 5′-monophosphate (amp)-activated protein kinase (ampk), the autophagosomal protein microtubule-associated protein 1 light chain 3c (lc3c), and the autophagy-related proteins beclin1, atg5, atg12 were significantly induced (P < 0.05) in the adenosine monophosphate-activated protein kinase/rapamycin (AMPK/mTOR) signaling pathway. These changes resulted in excess free radicals, causing oxidative stress in the mitochondrial membrane, promoting mitochondrial autophagy. The results confirm that deltamethrin exposure can induce hepatopancreatic injury by promoting mitochondrial autophagy, activating an immune response, and inhibiting lipid metabolism. Overall, this study provides multi-level information to reveal the toxic effects of deltamethrin on E. sinensis.

Ammonia Exposure-Induced Immunological Damage in Chicken Lymphoid Organs via TLR-7/MYD88/NF-κB Signaling Pathway and NLRP3 Inflammasome Activation.

Ammonia (NH3) is a hazardous gas that pollutes the environment and causes irritation. Its harmful effects on chickens, including its impact on their immune system, have previously been observed. However, the mechanism by which NH3 exposure causes immune system disorders in chickens remains unclear. The bursa of Fabricius (BF) and thymus are the two main lymphoid organs responsible for the proliferation, differentiation, and selection of B- and T-lymphocytes, both critical for the innate immune response of the host. In this study, we investigated the mechanism of NH3-induced immune dysregulation in broiler chickens. Transmission electron microscopy (TEM) revealed swollen mitochondria and breakage of the large crista lining, membrane deformation, chromatin condensation, increased vacuolation, and blood vessel spasms in the NH3-exposed BF and thymus tissues. Immunofluorescent analysis showed clustering of CD4+ and CD8+ cells, indicating an active immune response to NH3 exposure. Furthermore, NH3 exposure enhanced the mRNA expressions of Toll-like receptor 7 (TLR-7), myeloid differentiation primary response 88 (MYD88), and nuclear factor-kappa B (NF-κB), along with their proteins, and led to activation of the TLR-7/MyD88/NF-κB signaling pathway and NLRP3 inflammasome in chicken thymus tissues. Both mRNA and protein levels of key inflammation-related genes and proteins were upregulated in the NH3-treated group, highlighting a robust inflammatory response due to NH3 exposure. The specific findings of significant structural damage to key lymphoid organs and activation of inflammatory pathways in broiler chickens upon NH3 exposure can provide guidance for future, targeted therapies to improve poultry health.

Targeting S100A9-TLR2 axis controls macrophage NLRP3 inflammasome activation in fatty liver ischemia reperfusion injury

Abstract Liver ischemia reperfusion (IR) injury significantly impacts clinical outcomes by increasing the risk of hepatic dysfunction after liver surgery. Fatty livers are more susceptible to IR stress. Recent studies have demonstrated that S100A9 plays a crucial role in both IR injury and the progression of liver steatosis. Nevertheless, the precise mechanisms underlying these effects remain unclear. In our study, transcriptome analysis of fatty livers subjected to IR insult in mice identified S100A9 as an important mediator. Employing loss-of-function approaches, we investigated the immune regulatory function of S100A9 and its downstream signaling in fatty liver IR injury. As expected, S100A9 emerged as one of the most significantly upregulated genes during the reperfusion stage in fatty livers. Genetic knockdown of S100A9 markedly ameliorated liver pathological damage, evidenced by reduced macrophage/neutrophil infiltration as well as the decreased expression of proinflammatory factors. Transcriptome/functional studies revealed that S100A9 triggered liver inflammatory response via regulating Toll-like receptor 2 (TLR2)/Activating transcription factor 4 (ATF4) signaling. Additionally, TLR2 expression was notably increased in macrophages from ischemic fatty livers. In vitro, recombinant S100A9-stimulated macrophages exhibited the elevated production of proinflammatory factors and TLR2/ATF4 pathway activation. Intriguingly, S100A9 facilitated ATF4 nuclear translocation and enhanced NEK7/NLRP3 inflammasome activation in macrophages. In conclusion, our study identified S100A9 as a key regulator responsible for macrophage NLRP3 inflammasome activation and subsequent inflammatory injury in fatty liver IR process. Targeting TLR2/ATF4 signaling may offer a novel therapeutic strategy for mitigating S100A9-mediated liver injury.

TLR4-mediated chronic neuroinflammation has no effect on tangle pathology in a tauopathy mouse model.

Alzheimer's disease (AD) is marked by the accumulation of fibrillary aggregates composed of pathological tau protein. Although neuroinflammation is frequently observed in conjunction with tau pathology, current preclinical evidence does not sufficiently establish a direct causal role in tau tangle formation. This study aimed to evaluate whether chronic Toll-like receptor 4 (TLR4) stimulation, induced by a high dose of lipopolysaccharide (LPS, 5 mg/kg), exacerbates neurofibrillary tangle (NFT) pathology in a transgenic mouse model of tauopathy that expresses human truncated 151-391/3R tau, an early feature of sporadic AD. We utilized a transgenic mouse model of tauopathy subjected to chronic TLR4 stimulation via weekly intraperitoneal injections of LPS over nine consecutive weeks. Neurofibrillary tangle formation, microglial activation, and tau hyperphosphorylation in the brainstem and hippocampus were assessed through immunohistochemistry, immunofluorescence, and detailed morphometric analysis of microglia. Chronic LPS treatment led to a significant increase in the number of Iba-1+ microglia in the LPS-treated group compared to the sham group (p < 0.0001). Notably, there was a 1.5- to 1.7-fold increase in microglia per tangle-bearing neuron in the LPS-treated group. These microglia exhibited a reactive yet exhausted phenotype, characterized by a significant reduction in cell area (p < 0.0001) without significant changes in other morphometric parameters, such as perimeter, circumference, solidity, aspect ratio, or arborization degree. Despite extensive microglial activation, there was no observed reduction in tau hyperphosphorylation or a decrease in tangle formation in the brainstem, where pathology predominantly develops in this model. These findings suggest that chronic TLR4 stimulation in tau-transgenic mice results in significant microglial activation but does not influence tau tangle formation. This underscores the complexity of the relationship between neuroinflammation and tau pathology, indicating that additional mechanisms may be required for neuroinflammation to directly contribute to tau tangle formation.

Isomalto-Oligosaccharide Potentiates Alleviating Effects of Intermittent Fasting on Obesity-Related Cognitive Impairment during Weight Loss and the Rebound Weight Gain.

Obesity-related cognitive dysfunction poses a significant threat to public health. The present study demonstrated mitigating effects of intermittent fasting (IF) and its combination with isomalto-oligosaccharides and IF (IF + IMO) on cognitive impairments induced by a high-fat-high-fructose (HFHF) diet in mice, with IF + IMO exhibiting superior effects. Transcriptomic analysis of the hippocampus revealed that the protective effects on cognition might be attributed to the suppression of toll-like receptor 4 (TLR4)/NFκB signaling, oxidative phosphorylation, and neuroinflammation. Moreover, both IF and IF + IMO modulated the gut microbiome and promoted the production of short-chain fatty acids, with IF + IMO displaying more pronounced effects. IF + IMO-modulated gut microbiota, metabolites, and molecular targets associated with cognitive impairments were further corroborated using human data from public databases Gmrepo and gutMgene. Furthermore, the fecal microbiome transplantation confirmed the direct impacts of IF + IMO-derived microbiota on improving cognition functions by suppressing TLR4/NFκB signaling and increasing BDNF levels. Notably, prior exposure to IF + IMO prevented weight-regain-induced cognitive decline, suppressed TLR4/NFκB signaling and inflammatory cytokines in the hippocampus, and mitigated weight regain-caused gut dysbacteriosis without altering body weight. Our study underscores that IMO-augmented alleviating effects of IF on obesity-related cognitive impairment particularly during weight-loss and weight-regain periods, presenting a novel nutritional strategy to tackle obesity-related neurodegenerative disorders.

Resatovir Combined with Glycyrrhizic Acid Ameliorates Osteoarthritis and Enhances Autophagy in Chondrocytes

Background Osteoarthritis (OA) is a chronic disease worldwide. With resatovir usually used as an inhibitor, resatovir and glycyrrhizic acid have several pharmacological activities. Purpose We intend to explore the mechanism underlying resatovir combined with glycyrrhizic acid in OA. Methods After the establishment of an animal model of OA through anterior cruciate ligament transection and destabilization of the medial meniscus, the rats were subjected to intramuscular injection of resatovir combined with glycyrrhizic acid (60 mg/kg) or 5% glucose (60 mg/kg) every day for 4 weeks. During the progress, the rat movement and the bend score of knees were observed through behavioral studies. Additionally, the SKP2 gene expression and toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB)-related signaling pathways were examined, as apoptosis and autophagy were evaluated by flow cytometry. Results With increased inflammatory cells in the model group, treatment with resatovir combined with glycyrrhizic acid significantly decreased the number of inflammatory cells. Meanwhile, the treatment resulted in decreased SKP2 expression in OA cells when hindering the migration of preosteoclast cells. Interestingly, it was observed that the bend score increased over the treatment with resatovir plus glycyrrhizic acid and TIPPI% declined dramatically. Resatovir treatment enhanced autophagy and apoptosis in OA cells and decreased pP65, P65, and LC3 expression. Conclusion Resatovir combined with glycyrrhizic acid can inhibit the inflammatory response through decreasing SKP2 expression and induce autophagy activation in OA cells through TLR4/NF-κB signaling, thereby attenuating OA progression.