Effect of NETs/COX-2 pathway on immune microenvironment and metastasis in gastric cancer.

Background: Neutrophil extracellular traps (NETs) are crucial in the progression of several cancers. The formation of NETs is closely related to reactive oxygen species (ROS), and the granule proteins involved in nucleosome depolymerization under the action of ROS together with the loosened DNA compose the basic structure of NETs. This study aims to investigate the specific mechanisms of NETs promoting gastric cancer metastasis in order to perfect the existing immunotherapy strategies. Methods: In this study, the cells and tumor tissues of gastric cancer were detected by immunological experiments, real-time polymerase chain reaction and cytology experiments. Besides, bioinformatics analysis was used to analyze the correlation between cyclooxygenase-2 (COX-2) and the immune microenvironment of gastric cancer, as well as its effect on immunotherapy. Results: Examination of clinical specimens showed that NETs were deposited in tumor tissues of patients with gastric cancer and their expression was significantly correlated with tumor staging. Bioinformatics analysis showed that COX-2 was involved in gastric cancer progression and was associated with immune cell infiltration as well as immunotherapy. In vitro experiments, we demonstrated that NETs could activate COX-2 through Toll-like receptor 2 (TLR2) and thus enhance the metastatic ability of gastric cancer cells. In addition, in a liver metastasis model of nude mice we also demonstrated the critical role of NETs and COX-2 in the distant metastasis of gastric cancer. Conclusion: NETs can promote gastric cancer metastasis by initiating COX-2 through TLR2, and COX-2 may become a target for gastric cancer immunotherapy.

Histochemical assessment on osteoclasts in long bones of toll-like receptor 2 (TLR2) deficient mice.

OBJECTIVE: Toll-like receptor 2 (TLR2), recognizes a wide variety of pathogen-associated molecular patterns such as lipopolysaccharides, peptidoglycans, and lipopeptides, and is generally believed to be present in monocytes, macrophages, dendritic cells, and vascular endothelial cells. However, no histological examination of osteoclasts, which differentiate from precursors common to macrophages/monocytes, has been performed in a non-infected state of TLR2 deficiency. The objective of this study was to examine the histological properties and function of osteoclasts in the long bones of 8-week-old male TLR2 deficient (TLR2-/-) mice to gain insight into TLR2 function in biological circumstances without microbial infection. METHODS: Eight-week-old male wild-type and TLR2-/- mice were fixed with paraformaldehyde solution, and their tibiae and femora were used for micro-CT analysis, immunohistochemistry, transmission electron microscopy, and real-time PCR analysis. RESULTS: TLR2-/- tibiae and femora exhibited increased bone volume of metaphyseal trabeculae and elevated numbers of TRAP-positive osteoclasts. However, the number of multinucleated TRAP-positive osteoclasts was reduced, whereas mononuclear TRAP-positive cells increased, despite the high expression levels of Dc-Stamp and Oc-Stamp. Although TRAP-positive multinucleated and mononuclear osteoclasts showed the immunoreactivity and elevated expression of RANK and siglec-15, they revealed weak cathepsin K-positivity and less incorporation of the mineralized bone matrix, and often missing ruffled borders. It seemed likely that, despite the increased numbers, TLR2-/- osteoclasts reduced cell fusion and bone resorption activity. CONCLUSION: It seems likely that even without bacterial infection, TLR2 might participate in cell fusion and subsequent bone resorption of osteoclasts.

TLR2-hif1α-mediated glycolysis contributes to pyroptosis and oxidative stress in allergic airway inflammation.

As a pattern recognition receptor which activates innate immune system, toll-like receptor 2 (TLR2) has been reportedly mediates allergic airway inflammation (AAI), yet the underlying mechanism remains elusive. Here, in a murine AAI model, TLR2-/- mice showed decreased airway inflammation, pyroptosis and oxidative stress. RNA-sequencing revealed that allergen-induced hif1 signaling pathway and glycolysis were significantly downregulated when TLR2 was deficient, which were confirmed by lung protein immunoblots. Glycolysis inhibitor 2-Deoxy-d-glucose (2-DG) inhibited allergen-induced airway inflammation, pyroptosis, oxidative stress and glycolysis in wild type (WT) mice, while hif1α stabilizer ethyl 3,4-dihydroxybenzoate (EDHB) restored theses allergen-induced changes in TLR2-/- mice, indicating TLR2-hif1α-mediated glycolysis contributes to pyroptosis and oxidative stress in AAI. Moreover, upon allergen challenge, lung macrophages were highly activated in WT mice but were less activated in TLR2-/- mice, 2-DG replicated while EDHB reversed such effect of TLR2 deficiency on lung macrophages. Likewise, both in vivo and ex vivo WT alveolar macrophages (AMs) exhibited higher TLR2/hif1α expression, glycolysis and polarization activation in response to ovalbumin (OVA), which were all inhibited in TLR2-/- AMs, suggesting AMs activation and metabolic switch are dependent on TLR2. Finally, depletion of resident AMs in TLR2-/- mice abolished while transfer of TLR2-/- resident AMs to WT mice replicated the protective effect of TLR2 deficiency on AAI when administered before allergen challenge. Collectively, we suggested that loss of TLR2-hif1α-mediated glycolysis in resident AMs ameliorates allergic airway inflammation that inhibits pyroptosis and oxidative stress, therefore the TLR2-hif1α-glycolysis axis in resident AMs may be a novel therapeutic target for AAI.

Advanced Glycation End Products and Activation of Toll-like Receptor-2 and -4 Induced Changes in Aquaporin-3 Expression in Mouse Keratinocytes.

Prolonged inflammation and impaired re-epithelization are major contributing factors to chronic non-healing diabetic wounds; diabetes is also characterized by xerosis. Advanced glycation end products (AGEs), and the activation of toll-like receptors (TLRs), can trigger inflammatory responses. Aquaporin-3 (AQP3) plays essential roles in keratinocyte function and skin wound re-epithelialization/re-generation and hydration. Suberanilohydroxamic acid (SAHA), a histone deacetylase inhibitor, mimics the increased acetylation observed in diabetes. We investigated the effects of TLR2/TLR4 activators and AGEs on keratinocyte AQP3 expression in the presence and absence of SAHA. Primary mouse keratinocytes were treated with or without TLR2 agonist Pam3Cys-Ser-(Lys)4 (PAM), TLR4 agonist lipopolysaccharide (LPS), or AGEs, with or without SAHA. We found that (1) PAM and LPS significantly upregulated AQP3 protein basally (without SAHA) and PAM downregulated AQP3 protein with SAHA; and (2) AGEs (100 µg/mL) increased AQP3 protein expression basally and decreased AQP3 levels with SAHA. PAM and AGEs produced similar changes in AQP3 expression, suggesting a common pathway or potential crosstalk between TLR2 and AGEs signaling. Our findings suggest that TLR2 activation and AGEs may be beneficial for wound healing and skin hydration under normal conditions via AQP3 upregulation, but that these pathways are likely deleterious in diabetes chronically through decreased AQP3 expression.

Mechanism of Flemiphilippinin D Regulating Inflammatory Response in CIA Rats Through TLR2/MyD88/NF-κB Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo observe the effect of Flemiphilippinin D on collagen-induced arthritis （CIA） in rats and explore its mechanism. MethodForty rats were randomly divided into normal group， CIA group， methotrexate （MTX） group （1.35 mg·kg-1）， low-dose Flemiphilippinin D group （1.5 mg·kg-1）， and high-dose Flemiphilippinin D group （3.0 mg·kg-1）， with eight rats in each group. Except for the normal group， the CIA model was induced by type Ⅱ collagen. Each group was given corresponding liquid medicine or normal saline， once a week in the MTX group， and once a day in the Flemiphilippinin D groups for a total of 28 days. The arthritis score and joint swelling degree of rats were experimentally recorded. Pathological changes in the ankle joint of rats were observed by hematoxylin-eosin （HE） staining. Serum levels of inflammatory cytokines interleukin （IL）-1β， IL-6， IL-8， and tumor necrosis factor （TNF）-α were detected by enzyme-linked immunoabsorbent assay （ELISA）， and the mRNA expression of Toll-like receptor 2 （TLR2）， myeloid differentiation factor 88 （MyD88）， and nuclear transcription factor-κB （NF-κB） p65 were detected by Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）， and the protein expressions of TLR2， MyD88， and NF-κB p65 were detected by Western blot. ResultCompared with the normal group， the ankle joint of the CIA group was significantly swollen， and the clinical score of arthritis and the degree of joint swelling were significantly increased （P<0.01）. The ankle joint tissue structure was significantly damaged， and the levels of inflammatory factors IL-1β， IL-6， IL-8， and TNF-α in serum were significantly increased （P<0.01）. The mRNA levels and protein levels of TLR2， MyD88， and NF-κB p65 were significantly increased（P<0.01）. Compared with the CIA group， arthritis clinical score and joint swelling of rats in each administration group were significantly reduced （P<0.05， P<0.01）， and the pathological changes in the ankle joint were significantly improved. The contents of serum IL-1β， IL-6， IL-8， and TNF-α were significantly decreased （P<0.05， P<0.01）. The mRNA levels and protein levels of TLR2， MyD88， and NF-κB p65 in the ankle joint were significantly decreased （P<0.05， P<0.01）. ConclusionTo a certain extent， Flemiphilippinin D can reduce the expression of inflammatory factors in rheumatoid arthritis rats and play a good therapeutic effect. It works perhaps by inhibiting the activation of the TLR2/MyD88/NF-κB signaling pathway and thus shows an anti-inflammatory effect.

Lycium barbarum Polysaccharide Regulates Activation of RAW264.7 Macrophages Through MGL/TLR Pathway / 中国实验方剂学杂志

ObjectiveTo investigate the mechanism of Lycium barbarum polysaccharides （LBP） in promoting the activation of RAW264.7 macrophages. MethodRAW264.7 macrophages were stimulated with LBP at different concentrations （50， 100， 200 mg·L-1）， and those stimulated with lipopolysaccharide （LPS） at 100 μg·L-1 and galactose （Gal） at 100 mg·L-1 as positive controls. After 24 h of LBP stimulation， the cell counting kit-8 （CCK-8） was used to detect the survival rate of RAW264.7 macrophages treated with LBP （0， 50， 100， 200， 400， 800 mg·L-1）. The levels of interleukin-6 （IL-6） and interleukin-12 （IL-12） in cell culture supernatant were detected by enzyme-linked immunosorbent assay （ELISA）. The protein and mRNA expression of p38 mitogen-activated protein kinase （MAPK）， extracellular signal-regulated kinase （ERK）， c-Jun N-terminal kinase （JNK）， and nuclear factor κB （NF-κB） in Toll-like receptor 4 （TLR4）/Toll-like receptor 2 （TLR2）/macrophage galactose-type lectin （MGL） pathway of RAW264.7 macrophages was detected by Real-time fluorescence-based quantitative polymerase chain reaction （Real-time PCR） and Western blot. ResultCCK-8 results showed that compared with the results in the blank group， the survival rate of RAW264.7 macrophages decreased in the 400， 800 mg·L-1 LBP groups （P<0.05）. ELISA results showed that compared with the blank group， 50 mg·L-1 LBP could promote the secretion of IL-12 in RAW264.7 macrophages （P<0.01）. Compared with the blank group， 100 mg·L-1 LBP and 200 mg·L-1 LBP could promote the secretion of IL-6 in RAW264.7 macrophages （P<0.05， P<0.01）. Western blot results showed that compared with the blank group， the LBP groups （50， 100， 200 mg·L-1） enhanced protein expression levels of MAPK key molecules （p-p38 MAPK， p-ERK， p-NF-κB， and p-JNK） in TLR4， TLR2， and MGL pathways （P<0.05， P<0.01）. Compared with the model group， the 200 mg·L-1 LBP group could promote the expression level of p-NF-κB protein in RAW264.7 macrophages （P<0.01）. Real-time PCR results showed that compared with the blank group， the LBP groups （50， 100， and 200 mg·L-1） enhanced the mRNA expression levels of MAPK key molecules （p38 MAPK， ERK， NF-κB， and JNK） in TLR4 and TLR2 pathways （P<0.05， P<0.01）. Compared with the model group， the 50 and 200 mg·L-1 LBP groups could promote the mRNA expression levels of JNK and ERK2 in RAW264.7 macrophages （P<0.05， P<0.01）. ConclusionLBP can regulate the activation of RAW264.7 macrophages and participate in the immune response through the TLR2/TLR4/MGL pathway.

Anti-inflammatory Effect and Mechanism of Duhuo Jishengtang on Rheumatoid Arthritis Rats Based on TLR2/p38 MAPK/NF-κB Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo explore the anti-inflammatory effect of Duhuo Jishengtang （DHJST） on collagen-induced arthritis （CIA） model rats and its effect on the Toll-like receptor 2 （TLR2）/p38 mitogen-activated protein kinase （MAPK）/nuclear factor-κB （NF-κB） signaling pathway. MethodForty-eight male SD rats were randomly divided into the following six groups （n=8）： normal group， model group， methotrexate （MTX） group， low-dose DHJST （DHJST-L） group， medium-dose DHJST （DHJST-M） group， and high-dose DHJST （DHJST-H） group. The CIA model was established by injecting bovine type Ⅱ collagen into the rat tail root with the collagen antibody induction method. After model induction， rats were treated with drugs by gavage. The rats in the MTX group received MTX at 2.0 mg·kg-1， three times a week， and those in the DHJST groups received DHJST at 3.8， 7.6， 15.2 g·kg-1·d-1 for 28 days. The rats in the normal group and the model group were given the same dose of normal saline. The weight of the rats was recorded， and the paw swelling degree was observed. The arthritis index and immune organ index were measured， and the changes in the microcirculation indexes of the rats were detected with a microcirculation detector. Hematoxylin-eosin （HE） staining was used to detect the pathological morphologic changes in rat synovial tissues and the apoptosis rate of synovial cells was detected by flow cytometry to determine the therapeutic effect of DHJST on rheumatoid arthritis. Enzyme-linked immunosorbent assay （ELISA） was used to detect the changes in serum levels of tumor necrosis factor-α （TNF-α）， interleukin （IL）-1β， IL-17A， and interferon-γ （IFN-γ）. The protein expression of TLR2， NF-κB p65， phosphorylated NF-κB p65 （p-NF-κB p65）， p38 MAPK， and p-p38 MAPK was detected by Western blot. ResultCompared with the normal group， the model group showed reduced body weight （P<0.01）， increased paw swelling degree， arthritis index， and immune organ index （P<0.01）， increased comprehensive microvascular score and vascular resistance （P<0.01）， significant hyperplasia of synovial tissues and massive infiltration of inflammatory cells as revealed by pathological sections， and up-regulated expression levels of TNF-α， IL-1β， IL-17A， and IFN-γ in serum， and TLR2， p-NF-κB p65/NF-κB p65 and p-p38 MAPK/p38 MAPK in synovial tissues （P<0.01）. Compared with the model group， the DHJST groups showed increased body weight of rats （P<0.01）， decreased paw swelling degree， arthritis index， and immune organ index （P<0.05， P<0.01）， reduced comprehensive microvascular score and vascular resistance （P<0.05， P<0.01）， improved synovial histopathological injury， increased apoptosis rate of synovial cells （P<0.01）， and down-regulated levels of TNF-α， IL-1β， IL-17A， and IFN-γ in serum （P<0.05， P<0.01） and TLR2， p-NF-κB p65/NF-κB p65 and p-p38 MAPK/p38 MAPK in synovial tissues （P<0.05， P<0.01）. ConclusionDHJST may alleviate the inflammatory reaction in CIA rats by regulating the TLR2/p38 MAPK/NF-κB signaling pathway， thus exerting its anti-rheumatoid arthritis effect.

TGF-ß1 contributes to the hepatic inflammation in animal models with nonalcoholic steatohepatitis by Smad3/TLR2 signaling pathway.

Non-alcoholic fatty liver disease (NAFLD) is increasingly affecting human health and the economy worldwide due to various factors. Here, we found that the expression of TGF-ß1 and TLR2 was significantly up-regulated in liver samples from both rats and mice nonalcoholic steatohepatitis (NASH) models. By constructing corresponding cell model, we found that TGF-ß1 challenge can positively regulate the expression of TLR2 and p-Smad2/3, and the dual luciferase reporter gene system and EMSA assay confirmed the existence of Smad3 binding site (-916 ∼ -906) in the promoter region of TLR2. The overexpression and interference changes of Smad2/3 further verified the above experimental results. Taken together, these findings suggest that TGF-ß1 promotes TLR2 transcription and its target gene expression via Smad3, leading to malignant exacerbation of liver inflammation in NASH, which provides new insights into the treatment of NASH.

Toll-like receptor 2 signaling pathway activation contributes to a highly efficient inflammatory response in Japanese encephalitis virus-infected mouse microglial cells by proteomics.

Thousands of people die each year from Japanese encephalitis (JE) caused by the Japanese encephalitis virus (JEV), probably due to exacerbation of the inflammatory response that impairs the course of the disease. Microglia are mononuclear phagocytic cells located within the parenchyma of the central nervous system; these play a key role in the innate immune response against JEV infections. However, the involvement of toll-like receptor 2 (TLR2) in the inflammatory response during the early stages of JEV infection in BV2 cells remains. Here, we evaluated protein profiles and determined the role of TLR2 in the inflammatory response of JEV-infected BV2 cells. High-depth tandem mass tags labeling for quantitative proteomics was used to assess JEV infected-BV2 cells and compare immune response profiles at 6, 12, and 24 h post-infection (hpi). In total, 212 upregulated proteins were detected at 6 hpi, 754 at 12 h, and 191 at 24 h. According to GO and KEGG enrichment analysis, the upregulated proteins showed enrichment for proteins related to the immune response. Parallel reaction monitoring tests, western blotting, and qPCR results showed that the adaptor protein MyD88 was not activated. The expression levels of key proteins downstream of MyD88, such as IRAK1, IRAK4, and TRAF6 did not increase; however, the expression levels of PI3K-AKT did increase. By inhibiting key proteins (TLR2, PI3K, and AKT) we confirmed that JEV activated TLR2, thus resulting in a robust inflammatory response. Consequently, the TLR2-PI3K-AKT signaling axis was proven to play a critical in the early stages of the JEV infection-induced inflammatory response in microglia.

Clinical assessment and molecular mechanism of the upregulation of Toll-like receptor 2 (TLR2) in myocardial infarction.

OBJECTIVE: The prevalence and mortality of cardiovascular diseases remain ranked first worldwide. Myocardial infarction (MI) is the central cause of death from cardiovascular diseases, seriously endangering human health. The clinical implication of toll-like receptor 2 (TLR2) remains contradictory, and its mechanism is still unknown. Hence, the objective of this study was to elucidate the clinical value and molecular mechanism of TLR2 in MI. METHODS: All high-throughput datasets and eligible literature were screened, and the expression levels of TLR2 were collected from the MI. The integrated expression level of TLR2 was displayed by calculating the standardized mean difference (SMD) and the area under the curve (AUC) of the summary receiver operating characteristic curve (sROC). The related TLR2 genes were sent for pathway analyses by gene ontology (GO), Kyoto encyclopedia of genes and genome (KEGG), and disease ontology (DO). Single-cell RNA-seq was applied to ascertain the molecular mechanism of TLR2 in MI. RESULTS: Nine microarrays and four reported data were available to calculate the comprehensive expression level of TLR2 in MI, including 325 cases of MI and 306 cases of controls. The SMD was 2.55 (95% CI = 1.35-3.75), and the AUC was 0.76 (95% CI = 0.72-0.79), indicating the upregulation of TLR2 in MI. The related TLR2 genes were primarily enriched in the pathways of atherosclerosis, arteriosclerotic cardiovascular disease, and arteriosclerosis, suggesting the clinical role of TLR2 in the progression of MI. Afterward, TLR2 was upregulated in myeloid cells in MI. CONCLUSIONS: TLR2 may have a crucial role in progressing from coronary atherosclerosis to MI. The upregulation of TLR2 may have a favorable screening value for MI.

SJMHE1 protects against excessive iodine-induced pyroptosis in human thyroid follicular epithelial cells through a toll-like receptor 2-dependent pathway.

To elucidate the effect of Schistosoma japonicum peptide (SJMHE1) on pyroptosis in thyroid follicular epithelial cells (TFCs) induced by excessive iodine and the potential mechanism, the effects of SJMHE1 were investigated in NaI-treated Nthy-ori 3-1 cells; and the involvement of the ROS/MAPK/NF-κB signaling pathways in these effects was evaluated by employing CCK-8 assays, flow cytometry, ELISA, and Western blotting experiments. We found that SJMHE1 significantly reduced NLRP3, N-terminus of gasdermin D (GSDMD-N) and cleaved caspase-1 (C-caspase-1) expression, and decreased IL-1ß secretion in TFCs. SJMHE1 also markedly reduced reactive oxygen species (ROS) production, and decreased the phosphorylation levels of MAPK and NF-κB pathway members. Moreover, blocking of the Toll-like receptor 2 significantly impaired SJMHE1-mediated protection from excessive iodine-induced pyroptosis in TFCs. Therefore, our results suggested a protective role of SJMHE1 in excessive iodine-induced pyroptosis in TFCs, which might be attributed to its suppression for ROS/MAPK/NF-κB signaling pathway by binding of SJMHE1 with TLR2.

Pam2 lipopeptides enhance the immunosuppressive activity of monocytic myeloid-derived suppressor cells by STAT3 signal in chronic inflammation.

Chronic inflammation develops when the immune system is unable to clear a persistent insult. Unresolved chronic inflammation leads to immunosuppression to maintain the internal homeostatic conditions, which is mediated primarily by myeloid-derived suppressor cells (MDSCs). Toll-like receptors 2 (TLR2) has an important role in chronic inflammation and can be activated by a vast number and diversity of TLR2 ligands, for example Pam2CSK4. However, the regulatory effect of TLR2 signaling on MDSCs in chronic inflammation remains controversial. This study demonstrated that heat-killed Mycobacterium bovis BCG-induced pathology-free chronic inflammation triggered suppressive monocytic MDSCs (M-MDSCs) that expressed TLR2. Activation of TLR2 signaling by Pam2CSK4 treatment enhanced immunosuppression of M-MDSCs by upregulating inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) production partly through signal transducer and activator of transcription 3 (STAT3) activation. Thus, TLR2 has a fundamental role in promoting the MDSC-mediated immunosuppressive environment during chronic inflammation and might represent a potentially therapeutic target in chronic inflammation disease.

Activation of Host Immune Cells by Probiotic-Derived Extracellular Vesicles via TLR2-Mediated Signaling Pathways.

Since probiotic-derived extracellular vesicles (EVs) are capable of activating innate immunity, they are expected to be useful as novel adjuvants. To elucidate the mechanisms underlying the immunostimulatory effects of EVs released from probiotic cells, we newly investigated the role of Toll-like receptor 2 (TLR2) and immune cell downstream signaling in the generation of proinflammatory cytokines. Isolated Bifidobacterium- and Lactobacillus-derived EVs expressed peptidoglycan, one of the major pathogen-associated molecular patterns. EVs particle diameter were approximately 110-120 nm with a negative-zeta potential. The generation of proinflammatory cytokines (tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in TLR2-expressing mouse macrophage-like RAW264.7 cells and mouse dendritic DC2.4 cells treated with Bifidobacterium- and Lactobacillus-derived EVs decreased after the addition of T2.5, a TLR2 inhibitory antibody. Furthermore, we showed that the signaling pathways of c-Jun-NH2-terminal kinase (JNK)/mitogen-activated protein kinases (MAPK) and nuclear factor-kappaB (NF-κB) were also involved in the production of proinflammatory cytokines from EV-treated immune cells. These results provide valuable information for understanding of the host biological function induced by probiotic-derived EVs, which is helpful for developing an EV-based immunotherapeutic system.

Toll-like receptors 2 and 4 expression on peripheral blood lymphocytes and neutrophils of Egyptian multiple sclerosis patients.

BACKGROUND: Studies have just started delineating the role of Toll-like receptors (TLRs) in the pathogenesis of multiple sclerosis (MS). OBJECTIVES: To investigate the expression of TLR-2 and TLR-4 on peripheral blood neutrophils and lymphocytes in Egyptian patients with MS, and to examine the role of TLR-2 and TLR-4 expression as a candidate biomarker for MS diagnosis. METHODS: A total of 84 patients with newly diagnosed MS and 68 healthy controls were included in this study. The expression levels of TLR-2 and TLR-4 were assessed by flow cytometry technique using appropriate monoclonal antibodies. RESULTS: TLR-2 demonstrated a significantly higher expression on the lymphocytes and neutrophils of patients, whereas that of TLR-4 was significantly higher only on lymphocytes than those in the control group. However, there was no significant difference between patients with relapsing remitting MS and those with secondary progressive MS in terms of TLR-2 and TLR-4 expression. The expression of TLR-2 and TLR-4 on the lymphocytes and neutrophils of patients showed no significant correlation with either the duration of the disease or disability. The sensitivity and specificity of TLR-2 expression on lymphocytes and neutrophils to diagnose MS were 73.81%, 70.59%, 69.05%, and 52.94%, respectively. The sensitivity and specificity of TLR-4 expression on lymphocytes and neutrophils were 88.10%, 79.41%, 78.57%, and 76.47%, respectively. CONCLUSION: The expression of TLR-2 and TLR-4 on peripheral blood neutrophils and lymphocytes has a potential role in the pathogenesis of MS. TLR-4 expression on lymphocytes and neutrophils could be used as a potential biomarker to diagnose MS.

Aeromonas hydrophila infection induces Toll-like receptor 2 (tlr2) and associated downstream signaling in Indian catfish, Clarias magur (Hamilton, 1822).

Motile Aeromonas septicaemia (MAS), caused by Aeromonas hydrophila, is one of the most significant bacterial disease responsible for mortality in Indian catfish, Clarias magur, a potential aquaculture species in the Indian subcontinent. In fish, innate immunity elicited by pathogen recognition receptors (PRRs) plays an important role in providing protection against bacterial infection. Information on PRRs including Toll-like receptors (tlrs) and their response to bacterial pathogens remains unexplored in magur. Toll-like receptor 2 (tlr2), a phylogenetically conserved germ-line encoded PRR recognizes specific microbial structure and trigger MyD88-dependent signaling pathway to induce release of various cytokines responsible for innate immune response. In the present study, tlr2 gene of magur was characterized and downstream signaling was studied following challenge with A. hydrophila. The full-length cDNA of magur tlr2 (mtlr2) comprised of 3,066 bp with a single open reading frame of 2,373 bp encoding 790 amino acids having a theoretical pI value of 6.11 and molecular weight of 90 kDa. Structurally, it comprised of signal peptide (1-42aa), one leucine-rich repeat region (LRR) at N-terminal (LRR1-NT: 50-73 aa) and C-terminal (LRR-CT: 588-608 aa), twenty LRRs in between, one trans-membrane (Tm) domain (609-631aa) followed by cytoplasmic TIR domain (670-783aa). Phylogenetically, mtlr2 is closely related to pangasius and channel catfish. Highest basal expression of mtlr2, myd88 and il-1ß in spleen, nf-kb in anterior kidney was observed. Lowest basal expression of mtlr2 in skin and myd88, nf-kb and il-1ß in muscle was detected. Significant up-regulation of mtlr2 and downstream expression occurred at 3, 8, 24 h post infection to A. hydrophila in important immune organs such as liver, spleen, intestine and kidney. These findings highlight the vital role of tlr2 in eliciting innate immune defence against A. hydrophila infection.

Unilateral facial injection of Botulinum neurotoxin A attenuates bilateral trigeminal neuropathic pain and anxiety-like behaviors through inhibition of TLR2-mediated neuroinflammation in mice.

OBJECTIVES: In this study, we investigated the possible analgesic effects of Botulinum toxin type A (BoNT/A) on trigeminal neuralgia (TN). A modified TN mouse model was established by chronic constriction injury of the distal infraorbital nerve (dIoN-CCI) in mice, and the possible roles of microglia toll-like receptor 2 (TLR2) and neuroinflammation was investigated. METHODS: Male C57BL/6 mice were divided into 3 groups, including sham group, vehicle-treated TN group and BoNT/A-treated TN group. Bilateral mechanical pain hypersensitivity, anxiety-like and depressive-like behaviors were evaluated by using von Frey test, open field, elevated plus-maze testing, and forced swimming test in mice, respectively. The mRNA or protein expression levels of toll-like receptors (TLRs), glia activation markers and proinflammatory factors in the trigeminal nucleus caudalis (TNC) were tested by RT-qPCR, immunofluorescence and Western blotting. We also tested the pain behaviors of TN in Tlr2-/- mice. RESULTS: We found that unilateral subcutaneous injection of BoNT/A into the whisker pad on the ipsilateral side of dIoN-CCI mice significantly attenuated bilateral mechanical pain hypersensitivity and anxiety-like behaviors induced by dIoN-CCI surgery in mice. The dIoN-CCI surgery significantly up-regulated the expression of TLR2, MyD88, CD11b (a microglia marker), IL-1ß, TNF-α and IL-6 in the ipsilateral TNC in mice, and BoNT/A injection significantly inhibited the expression of these factors. Immunostaining results confirmed that BoNT/A injection significantly inhibited the microglia activation in the ipsilateral TNC in dIoN-CCI mice. TLR2 deficiency also alleviated bilateral mechanical pain hypersensitivity and the up-regulation of MyD88 expression in the TNC of dIoN-CCI mice. CONCLUSION: These results indicate that unilateral injection of BoNT/A attenuated bilateral mechanical pain hypersensitivity and anxiety-like behaviors in dIoN-CCI mice, and the analgesic effects of BoNT/A may be associated with the inhibition of TLR2-mediated neuroinflammation in the TNC.

IFN-γ contributes to the hepatic inflammation in HFD-induced nonalcoholic steatohepatitis by STAT1ß/TLR2 signaling pathway.

Growing research evidence suggests that elevated TLR2 is closely related to the occurrence and development of nonalcoholic steatohepatitis (NASH). However, a little is known about its regulatory mechanism. Here, we found that IFN-γ and TLR2 expression is significantly upregulated in NASH associated rat liver specimens. Meanwhile, IFN-γ positively regulated the expression of TLR2 and its target genes in NR8383 rat macrophage cells in dose- & time-dependent manner. Importantly, IFN-γ also regulated the related transcriptional factors pSTAT1 and IRF1. Moreover, we identified that the DNA fragment from -1000 to -200 bp of the TLR2 promoter region is responsible for STAT1 binding, especially the STAT1-BS3 (-591∼-573 bp). Further investigation verified that STAT1ß is essential in this process, rather than STAT1α. Overall, our findings suggest that IFN-γ promotes TLR2 transcription and its target genes expression by STAT1ß. This leads to the hepatic inflammation vicious cycle in NASH and provides new potential targets for treating NASH.

Single Nucleotide Polymorphisms in the Bovine TLR2 Extracellular Domain Contribute to Breed and Species-Specific Innate Immune Functionality.

Recent evidence suggests that several cattle breeds may be more resistant to infection with the zoonotic pathogen Mycobacterium bovis. Our data presented here suggests that the response to mycobacterial antigens varies in macrophages generated from Brown Swiss (BS) and Holstein Friesian (HF) cattle, two breeds belonging to the Bos taurus family. Whole genome sequencing of the Brown Swiss genome identified several potential candidate genes, in particular Toll-like Receptor-2 (TLR2), a pattern recognition receptor (PRR) that has previously been described to be involved in mycobacterial recognition. Further investigation revealed single nucleotide polymorphisms (SNP) in TLR2 that were identified between DNA isolated from cells of BS and HF cows. Interestingly, one specific SNP, H326Q, showed a different genotype frequency in two cattle subspecies, Bos (B.) taurus and Bos indicus. Cloning of the TLR2 gene and subsequent gene-reporter and chemokine assays revealed that this SNP, present in BS and Bos indicus breeds, resulted in a significantly higher response to mycobacterial antigens as well as tri-acylated lipopeptide ligands in general. Comparing wild-type and H326Q containing TLR2 responses, wild-type bovine TLR2 response showed clear, diminished mycobacterial antigen responses compared to human TLR2, however bovine TLR2 responses containing H326Q were found to be partially recovered compared to human TLR2. The creation of human:bovine TLR2 chimeras increased the response to mycobacterial antigens compared to the full-length bovine TLR2, but significantly reduced the response compared to the full-length human TLR2. Thus, our data, not only present evidence that TLR2 is a major PRR in the mammalian species-specific response to mycobacterial antigens, but furthermore, that there are clear differences between the response seen in different cattle breeds, which may contribute to their enhanced or reduced susceptibility to mycobacterial infection.

Toll-like receptor 2 downregulation and cytokine dysregulation predict mortality in patients with Staphylococcus aureus bacteremia.

BACKGROUND: Staphylococcus aureus bacteremia (SAB) presents heterogeneously, owing to the differences in underlying host conditions and immune responses. Although Toll-like receptor 2 (TLR2) is important in recognizing S. aureus, its function during S. aureus infection remains controversial. We aimed to examine the association of TLR2 expression and associated cytokine responses with clinical SAB outcomes. METHODS: Patients from a prospective SAB cohort at two tertiary-care medical centers were enrolled. Blood was sampled at several timepoints (≤5 d, 6-9 d, 10-13 d, 14-19 d, and ≥ 20 d) after SAB onset. TLR2 mRNA levels were determined via real-time PCR and serum tumor necrosis factor [TNF]-α, interleukin [IL]-6, and IL-10 levels were analyzed with multiplex-high-sensitivity electrochemiluminescent ELISA. RESULTS: TLR2 levels varied among 59 SAB patients. On days 2-5, TLR2 levels were significantly higher in SAB survivors than in healthy controls (p = 0.040) and slightly but not significantly higher than non-survivors (p = 0.120), and SAB patients dying within 7 d had lower TLR2 levels than survivors (P = 0.077) although statistically insignificant. IL-6 and IL-10 levels were significantly higher in non-survivors than in survivors on days 2-5 post-bacteremia (P = 0.010 and P = 0.021, respectively), and those dying within 7 d of SAB (n = 3) displayed significantly higher IL-10/TNF-α ratios than the survivors did (P = 0.007). CONCLUSION: TLR2 downregulation and IL-6 and IL-10 concentrations suggestive of immune dysregulation during early bacteremia may be associated with mortality from SAB. TLR2 expression levels and associated cytokine reactions during early-phase SAB may be potential prognostic factors in SAB, although larger studies are warranted.

Toll-like receptors 2 expression in mediastinal lymph node of patients with sarcoidosis.

BACKGROUND: Toll-like receptors (TLRs) play a vital role as a first defense mechanism linking the innate with the adaptive immune system. Prior studies showed that TLR2 participated in immune responses of sarcoidosis. However, the role of TLR2 in the progression of mediastinal lymph nodes associated with sarcoidosis is still unknown. The current study aims to investigate the expression of Toll-like receptors 2 (TLR2) in mediastinal lymph nodes of patients with sarcoidosis. METHODS: Mediastinal lymph nodes biopsy specimens were collected from 10 patients with sarcoidosis and 11 normal controls. The expression of TLR2 in mediastinal lymph nodes was detected by immunohistochemistry. RESULTS: In mediastinal lymph nodes specimens, immunohistochemical examination revealed that expression of TLR2 could be detected in sarcoidosis patients, while it was scarcely detected in the mediastinal lymph nodes of control. The mean optical density of TLR2 in mediastinal lymph nodes of sarcoidosis was significantly higher than controls (124.9±24.3 vs. 92.6±35.2, P=0.026). Among patients with sarcoidosis, correlation analysis showed that the mean optical density of TLR2 in mediastinal lymph nodes positively correlated with the level of 24-hour urinary calcium (R=0.781, P=0.038). CONCLUSIONS: The expression of TLR2 was upregulated in mediastinal lymph nodes of sarcoidosis patients. The expression of TLR2 in mediastinal lymph nodes was associated with the level of 24-hour urinary calcium, suggesting that TLR2 might become another predictor of disease activity.