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Schizophrenia (SZ) is a chronic disabling mental disorder with high heritability, and several immune-regulating genes have been implicated in its pathophysiology In this study, we investigated the expression of Toll-like receptors (TLRs) 1, 2, and 6 in peripheral blood monocytes from SZ patients and healthy control subjects (HCSs) in the Mexican population, focusing on specific SZ-associated gene variants. Gene expressions were assessed by qPCR, and protein expression was measured using flow cytometry. The secretory profiles of MALP2-stimulated monocytes were evaluated through immunoproteomic arrays. Our results indicate that patients with SZ carrying the rs4833093/TLR1 GG genotype exhibited significantly lower TLR1 gene expression compared to TT carriers. Notably, HCSs with the TT genotype showed markedly higher TLR1 protein expression, while all patients with SZ exhibited significantly reduced protein levels regardless of genotype. Furthermore, monocytes from patients with SZ displayed altered secretion profiles upon TLR stimulation, with significant elevations in IL-18, uPAR, angiopoietin-2, and serpin E1, alongside reductions in MCP-1, IL-17A, IL-24, MIF, and myeloperoxidase compared to HCSs. These findings suggest a dysfunctional TLR-mediated innate immune response in SZ. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs) are expressed on both immune cells and tumor cells, triggering both anti-tumor and pro-tumor responses. Therefore, TLRs have potential as prognostic biomarkers and immunotherapeutic targets. The aim of this study was to investigate TLR1, TLR2, TLR4, TLR5, and TLR6 expression and association with clinicopathological variables and survival in gastric cancer. Immunohistochemical study on cancer specimens from 564 resected gastric cancer patients was performed using tissue microarrays. The association between patient survival and TLR expression was calculated with Cox regression adjusted for confounding factors. Patients with high cytoplasmic TLR2 expression had significantly poorer 5-year survival than the low cytoplasmic TLR2 expression group in multivariate analysis (adjusted HR 1.38, 95% CI 1.11–1.71), and this estimate was similar in intestinal type (adjusted HR 1.33, 95% CI 0.98–1.80) and diffuse type (adjusted HR 1.48, 95% CI 1.06–2.05) histology subgroups. Patients with high cytoplasmic TLR6 expression group had significantly better 5-year survival compared with low cytoplasmic TLR6 expression group in multivariate analysis (adjusted HR 0.74, 95% CI 0.60–0.91). In the subgroup analysis of diffuse type of histology, the 5-year survival was better in high cytoplasmic TLR6 expression group in multivariable analysis (HR 0.62, 95% CI 0.46–0.83). In the intestinal type of histology subgroup, no significant differences between the groups were present. TLR1, TLR4, and TLR5 expression were not associated with 5-year survival. In conclusion, cytoplasmic TLR2 and TLR6 expression seem to have independent prognostic impact in gastric cancer, while TLR1, TLR4, and TLR5 do not. [ABSTRACT FROM AUTHOR]

Objective: To investigate potential mechanism of Helicobacter pylori metabolites antagonizing host innate immunity. Methods: RNA sequencing and pathway enrichment analysis were used to analyze only LPS-stimulated gastric mucosal cells GES-1, GES-1 cells co-treated with LPS and Helicobacter pylori culture supernatant, and untreated GES-1 cells. The culture supernatant of Helicobacter pylori was filtered by a 3KD ultrafiltration tube, and the filtered filtrate (metabolite part) and the retained solution (protein part) were treated with LPS-stimulated GES-1 cells to detect activity of NF-κB pathway, phosphorylation level of NF-κB, secretion levels of NF-κB pathway effectors TNF-α, IL-6 and IL-8. Identification of key metabolites by untargeted metabolic mass spectrometry. Results: Compared with GES-1 cells stimulated only by LPS, after co-treated with LPS and Helicobacter pylori culture supernatant, expression levels of various genes were regulated and tended to the level of GES-1 in untreated gastric mucosal cells, mainly in the NF-κB pathway. After co-treatment with LPS and culture supernatant of Helicobacter pylori, activity of NF-κB pathway was inhibited (P< 0.05). Helicobacter pylori metabolites could inhibit the activity of NF-κ B pathway, inhibit phosphorylation of NF-κB, and inhibit the secretion of NF-κB pathway effectors TNF-α, IL-6 and IL-8 (P<0.05). 1, 5 and 25 µmol/L of Helicobacter pylori metabolite 2-D-Glu-copyranose (2DG) treatment inhibited activity of NF-κB pathway and phosphorylation of NF-κB in GES-1 cells, and secretion of NF-κB pathway effectors TNF-α, IL-6 and IL-8 were inhibited (P<0.05). After 2DG treatment, activity of NF-κB in GES-1 cells with TLR3, TLR4, TLR5, TLR6, TLR7, TLR8, TLR9 and TLR10 knockout were significantly decreased (P<0.05); while there was no significant changes in activity of NF-κB in TLR1 and TLR2 knockout GES-1 cells. Both TLR1 and TLR2 interactions were attenuated in GES-1 cells after 2DG treatment. Molecular docking showed that 2DG could bind to TLR2 amino acid disabled R321, K347 and F349, the binding energy was -12 kcal/mol. TLR2 wild-type and mutant plasmids (R321K, K347R, F349A) were constructed, and TLR2-knockout GES-1 cells were respectively transfected. It was found that 2DG treatment did not reduce NF-κB activity in GES-1 cells transfected with TLR2 mutant. Conclusion: Helicobacter pylori metabolite 2DG can interact with TLR2, reduce the formation of heterodimers between TLR2 and TLR1, and inhibit the activity of innate immune NF-κB pathway. [ABSTRACT FROM AUTHOR]

AbstractNon-mammal models are gaining popularity due to their ease of maintenance, low cost and lack of ethical restrictions. As some processes taking place in insect hemocytes are mirrored in human immunocytes, many immunological studies are now turning to the use of insect models like Galleria mellonella. G. mellonella larvae are susceptible to infection by Conidiobolus coronatus: an entomopathogenic fungus causing rhinofacial mycosis in humans. The study examines G. mellonella larvae during C. coronatus infection for the presence of certain compounds known to be involved in the human immunological response (histamine, HSF1, Cysteinyl leukotriene TLR1 and TLR2). G. mellonella larvae were exposed to fully grown fungus, and the results were determined by ELISA tests, fluorescence microscopy and flow cytometry. CysLT showed no significant changes between the control group and the infected larvae. Both histamine and HSF1 levels increased significantly after exposure to C. coronatus. Immunolocalization and flow cytometry of TLR1 and TLR2 proves that both receptors increase their levels due to the fungus infection. Our findings show that the cellular response of the G. mellonella is similar to the human response, indicating that G. mellonella larvae may be considered as a human-like immunological model in further studies.

Carlo E Sotelo-Ramírez,1,2 Beatriz Camarena,2 Marco Antonio Sanabrais-Jiménez,2 Julio Uriel Zaragoza-Hoyos,2 Bruno Ordoñez-Martínez,2 Raul I Escamilla-Orozco,3 Beatriz Gómez-González4 1Posgrado en Biología Experimental, Universidad Autónoma Metropolitana-Iztapalapa, México City, México; 2Departamento de Farmacogenética, Instituto Nacional de Psiquiatría Ramon de la Fuente Muñiz, Mexico City, Mexico; 3Dirección de Servicios Clínicos, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México; 4Área de Neurociencias, Departamento de Biología de la Reproducción, Universidad Autónoma Metropolitana-Iztapalapa, Ciudad de México, MéxicoCorrespondence: Beatriz Camarena, Departamento de Farmacogenética, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calz México-Xochimilco, 101, Col. San Lorenzo Huipulco, México City, 14370, Mexico, Tel +52554160-5075, Email bcamarenam@gmail.comIntroduction: Schizophrenia is a complex psychiatric disorder with an important genetic contribution. Immunological abnormalities have been reported in schizophrenia. Toll-like receptor (TLR) genes play an important role in the activation of the innate immune response, which may help to explain the presence of inflammation in people with this disorder. The aim of this study was to analyze the association of TLR1, TLR2, and TLR6 gene polymorphisms in the etiology of schizophrenia.Methods: We included 582 patients with schizophrenia and 525 healthy controls. Genetic analysis was performed using allelic discrimination with TaqMan probes.Results: We observed significant differences between patients and controls in the genotype and allele frequencies of TLR1/rs4833093 (χ 2 = 17.3, p = 0.0002; χ 2 = 15.9, p = 0.0001, respectively) and TLR2/rs5743709 (χ 2 = 29.5, p = 0.00001; χ 2 = 7.785, p = 0.0053, respectively), and in the allele frequencies of TLR6/rs3775073 (χ 2 = 31.1, p = 0.00001). Finally, we found an interaction between the TLR1/rs4833093 and TLR2/rs5743709 genes, which increased the risk of developing schizophrenia (OR = 2.29, 95% CI [1.75, 3.01]).Discussion: Our findings add to the evidence suggesting that the activation of innate immune response might play an important role in the development of schizophrenia.Keywords: TLR1, TLR2, TLR6, gene–gene interaction, schizophrenia, immune response

Non-mammal models are gaining popularity due to their ease of maintenance, low cost and lack of ethical restrictions. As some processes taking place in insect hemocytes are mirrored in human immunocytes, many immunological studies are now turning to the use of insect models like Galleria mellonella. G. mellonella larvae are susceptible to infection by Conidiobolus coronatus: an entomopathogenic fungus causing rhinofacial mycosis in humans. The study examines G. mellonella larvae during C. coronatus infection for the presence of certain compounds known to be involved in the human immunological response (histamine, HSF1, Cysteinyl leukotriene TLR1 and TLR2). G. mellonella larvae were exposed to fully grown fungus, and the results were determined by ELISA tests, fluorescence microscopy and flow cytometry. CysLT showed no significant changes between the control group and the infected larvae. Both histamine and HSF1 levels increased significantly after exposure to C. coronatus. Immunolocalization and flow cytometry of TLR1 and TLR2 proves that both receptors increase their levels due to the fungus infection. Our findings show that the cellular response of the G. mellonella is similar to the human response, indicating that G. mellonella larvae may be considered as a human-like immunological model in further studies. [ABSTRACT FROM AUTHOR]

Background: Bipolar disorder (BD) is a complex neuropsychiatric disease that has been strongly linked to immune dysregulation. In particular, an abnormal inflammatory response mediated by toll-like receptor 2 − 1/6 (TLR2-1/6) was described in BD. Nevertheless, genetic factors' contribution is still unknown. Thus, we suggested that functional polymorphisms of TLR2, 1 and 6 could be involved in BD predisposition. Methods and results: TLR2, 1 and 6 polymorphisms were genotyped by PCR-RFLP in 292 controls and 131 patients from a Tunisian population. Polymorphisms and haplotype associations were explored in BD and binary logistic regression analysis was performed for more powerful associations. In dominant model, we found a significantly higher genotype and minor allele frequencies in healthy females compared to patients for TLR2-196-174Ins/Del (p = 0.04; OR = 0.3, p = 0.04; OR = 0.3, respectively) and for TLR6-S249P only with minor allele (p = 0.03; OR = 0.2). In contrast, TLR2-R677W CT + TT and T allele frequencies were significantly higher in BD (padjusted<10− 4; ORadjusted =46.6, p < 10− 4; OR = 6.3, respectively), specifically in females (CT + TT: 100%). Similarly, TLR1-R80T showed significantly increased GC + CC and C allele frequencies in patients compared to controls (padjusted=0.04; ORadjusted=4, p = 0.009; OR = 4.3, respectively). Moreover, haplotype investigation demonstrated that InsGTCGT (p < 10− 4, OR = 275) and delGCCGT (p = 0.03, OR = 18.5) were significantly overrepresented in BD patients compared to controls. Conclusions: We suggest that TLR2-196-174Ins/Del and TLR6-S249P could be protective factors of females against BD. However, TLR2-R677W and TLR1-R80T could be strongly associated with higher risk of BD. Interestingly, TLR2-R677W could be a genetic marker for BD in females. However, further studies with larger groups are needed to confirm these findings. [ABSTRACT FROM AUTHOR]

The aim of the work was to evaluate the diagnostic value of TLR2 and TLR4 expression on periodontal and peripheral blood lymphoid cells by immunofluorescence microscopy in patients with chronic periodontitis associated with key periodontal pathogenic species Filifactor alocis, Porphyromonas gingivalis. Materials and methods. The study included 150 patients 88 (59%) women and 62 (41%) men aged 18 to 73 years with chronic periodontitis in the acute phase (CP) and 32 people without signs of chronic periodontal inflammation. To confirm the diagnosis of periodontitis, the Multident-5 PCR kit was used (detection of P. gingivalis, Prevotella intermedia, Tannerella forsythia, Treponema denticola, Aggregatibacter actinomycetemcomitans), as well as rt-PCR for F. alocis and P. gingivalis in the contents of the periodontal pocket (NPF GenLab, Russia). To evaluate cells carrying CD282 and CD284 markers, gingival fluid flushes from the periodontal pocket with Hanks' solution were used. The isolated cells were stained with antibodies to CD282 markers (corresponding to TLR2 receptor) or CD284 (corresponding to TLR4 receptor) labeled with FITC, and fixed with paraformaldehyde for subsequent immunofluorescence microscopy. Results. The expression of TLR2 and TLR4 on peripheral blood and gingival fluid leukocytes was studied in individuals with healthy periodontitis and patients with chronic periodontitis associated with F. alocis, P. gingivalis. According to the results of PCR, the detection rate of F. alocis and P. gingivalis was 64 and 62.7%, respectively, which confirmed their dominance in the microbial association. It was found that the expression of TLR2 and TLR4 on peripheral blood lymphoid cells varied in humans. The possible diagnostic significance of this phenomenon in assessing the progression of chronic periodontitis is discussed. Conclusion. In patients with chronic periodontitis associated with the dominance of periodontopathogenic species F. alocis, P. gingivalis, the multidirectional expression of TLR2 and TLR4 on peripheral blood cells was observed, which may have diagnostic significance in assessing the progression of periodontal diseases.

Background: Single nucleotide variants in toll-like receptor genes play a crucial role in leprosy susceptibility or resistance. Methods: With an epidemiology case–control study, associations between SNVs rs5743618 in TLR1, rs5743708 in TLR2, and rs5743810 in TLR6 and overall susceptibility for leprosy were estimated in 114 cases and 456 controls. Following that, stratified analysis was performed. DNA was extracted from peripheral blood. Genotyping was performed using predesigned TaqMan probes. Results: The A/G genotype of rs5743810 behaved as a protective factor for the development of leprosy in the codominant (OR= 0.37; 95% CI = 016–0.86, p = 0.049) and over-dominant (OR = 0.38; 95% CI = 0.16–0.88, p = 0.019) inheritance models. The A/G and A/A genotypes behaved as a protective factor (OR = 0.39; 95% CI = 0.17–0.87, p = 0.016) in the dominant model. The SNVs rs5743618 and rs5743708 showed no association with any of the models. The CGG haplotype (rs5743618–rs5743708–rs5743810) behaved as a susceptibility factor for developing leprosy (OR = 1.86; 95% CI = 1.11–3.10, p = 0.019). The latter haplotype behaved as a susceptibility factor for leprosy development in women (OR = 2.39; 95% CI = 1.21–4.82, p = 0.013). Conclusions: The identified variants in the genes encoding TLRs, specifically rs5743810 in TLR6 and CGG (rs5743618–rs5743708–rs5743810) haplotypes, may somehow explain leprosy susceptibility in the studied population in a leprosy endemic region in Colombia.

Leprosy is a chronic disease and also a global health issue, with a high number of new cases per year. Toll-like receptors can respond to mycobacterial molecules in the early stage of infection. As important components of the innate immune response, alterations in genes coding for these receptors may contribute to susceptibility/protection against diseases. In this context, we used a casecontrol study model (183 leprosy cases vs. 185 controls) to investigate whether leprosy patients and the control group, in southern Brazil, have different frequencies in TLR1 (TLR1 G>T; rs5743618), TLR2 (TLR2 T>C, rs1816702 and rs4696483), and TLR4 (TLR4 A>G, rs1927911) polymorphisms. Analysis of the TLR1 1805G>T polymorphism presented the G/G genotype more frequently in the control group. TLR2 T>C rs1816702 and TLR2 T>C rs4696483, the T/T and C/T genotype, respectively, were more frequent in the control group than in leprosy patients, suggesting protection from leprosy when the T allele is present (rs4696483). Haplotype analyses between TLR1 (rs5743618) and TLR2 (rs1816702 and rs4696483) polymorphisms suggest risk for the presence of the TCC haplotype and protection in the presence of the TCT haplotype. This study suggests that polymorphisms in TLR1 and TLR2 are factors that may contribute to development/resistance of leprosy. [ABSTRACT FROM AUTHOR]

Leprosy is a chronic disease and also a global health issue, with a high number of new cases per year. Toll-like receptors can respond to mycobacterial molecules in the early stage of infection. As important components of the innate immune response, alterations in genes coding for these receptors may contribute to susceptibility/protection against diseases. In this context, we used a case-control study model (183 leprosy cases vs. 185 controls) to investigate whether leprosy patients and the control group, in southern Brazil, have different frequencies in TLR1 (TLR1 G>T; rs5743618), TLR2 (TLR2 T>C, rs1816702 and rs4696483), and TLR4 (TLR4 A>G, rs1927911) polymorphisms. Analysis of the TLR1 1805G>T polymorphism presented the G/G genotype more frequently in the control group. TLR2 T>C rs1816702 and TLR2 T>C rs4696483, the T/T and C/T genotype, respectively, were more frequent in the control group than in leprosy patients, suggesting protection from leprosy when the T allele is present (rs4696483). Haplotype analyses between TLR1 (rs5743618) and TLR2 (rs1816702 and rs4696483) polymorphisms suggest risk for the presence of the TCC haplotype and protection in the presence of the TCT haplotype. This study suggests that polymorphisms in TLR1 and TLR2 are factors that may contribute to development/resistance of leprosy.

CD71+ erythroid cells (CECs) were only known as erythrocyte progenitors not so long ago. In present times, however, they have been shown to be active players in immune regulation, especially in immunosuppression by the means of ROS, arginase-1 and arginase-2 production. Here, we uncover organ-of-origin differences in cytokine gene expression using NanoString and protein production using Bio-Plex between CECs from healthy human adult bone marrow and from human fetal liver parenchyma. Namely, healthy human adult bone marrow CECs both expressed and produced IFN-a, IL-1b, IL-8, IL-18 and MIF mRNA and protein, while human fetal liver parenchyma CECs expressed and produced IFN-a, IL15, IL18 and TNF-b mRNA and protein. We also detected TLR2 and TLR9 gene expression in both varieties of CECs and TLR1 and NOD2 gene expression in human fetal liver parenchyma CECs only. These observations suggest that there might be undiscovered roles in immune response for CECs. [ABSTRACT FROM AUTHOR]

Toll‐like receptors are membrane‐bound proteins which plays a vital role in the regulation of innate immune response which is involved in various inflammatory disorders. 3,6‐Dihydroxyflavone (3,6‐DHF) is a known chemo preventive agent which is used in the treatment of various cancers including breast cancer and an effective JNK kinase inhibitor which can efficiently block the TLR2‐mediated signaling pathways. In this current study, we have explored inhibition of 3,6‐DHF in TLR2/TLR1 heterodimerization. We stimulated HEK cells by Pam3CSK4 which specifically induced inflammation through TLR2/TLR1 binding. Secretion of the inflammatory cytokine in Pam3CSK4‐induced HEK293‐hTLR2 cells was considerably reduced by 3,6‐DHF, implying that 3,6‐DHF inhibited Pam3CSK4‐induced TLR2/TLR1 signaling specifically. In addition, 3,6‐DHF did not cause severe cytotoxicity against human embryonic kidney (HEK) cells at high concentration up to 100 μM. The binding affinity of 3,6‐DHF to TLR2 and TLR1 was explored with 10−5 affinity using bio‐layer interferometry and molecular docking studies identified the important active site residues that participate in the inhibition of TLR2/TLR1 heterodimerization. Our results showed that 3,6‐DHF inhibits TLR2‐mediated inflammatory signaling by direct binding and the insights in designing more potent drug candidates by targeting the interacting crucial active site residues in TLR2/TLR1. [ABSTRACT FROM AUTHOR]

Background Toll like receptors (TLRs) are an important and evolutionary conserved class of pattern recognition receptors associated with innate immunity. The recognition of Gram-positive cell wall constituents strongly depends on TLR2. In order to be functional, TLR2 predominantly forms a heterodimer with TLR1 or TLR6 within specialized membrane microdomains, the lipid rafts. The membrane lipid composition and the physicochemical properties of lipid rafts are subject to modification by exogenous fatty acids. Previous investigations of our group provide evidence that macrophage enrichment with polyunsaturated fatty acids (PUFA) induces a reordering of lipid rafts and non-rafts based on the incorporation of supplemented PUFA as well as their elongation and desaturation products. Methods In the present study we investigated potential constraining effects of membrane microdomain reorganization on the clustering of TLR2 with its co-receptors TLR1 and TLR6 within lipid rafts. To this end, RAW264.7 macrophages were supplemented with either docosahexaenoic acid (DHA) or arachidonic acid (AA) and analyzed for receptor expression and microdomain localization in context of TLR stimulation. Results and Conclusions Our analyses showed that receptor levels and microdomain localization were unchanged by PUFA supplementation. The TLR2 pathway, in contrast to the TLR4 signaling cascade, is not affected by exogenous PUFA at the membrane level.

Background: Toll like receptors (TLRs) are an important and evolutionary conserved class of pattern recognition receptors associated with innate immunity. The recognition of Gram-positive cell wall constituents strongly depends on TLR2. In order to be functional, TLR2 predominantly forms a heterodimer with TLR1 or TLR6 within specialized membrane microdomains, the lipid rafts. The membrane lipid composition and the physicochemical properties of lipid rafts are subject to modification by exogenous fatty acids. Previous investigations of our group provide evidence that macrophage enrichment with polyunsaturated fatty acids (PUFA) induces a reordering of lipid rafts and non-rafts based on the incorporation of supplemented PUFA as well as their elongation and desaturation products. Methods: In the present study we investigated potential constraining effects of membrane microdomain reorganization on the clustering of TLR2 with its coreceptors TLR1 and TLR6 within lipid rafts. To this end, RAW264.7 macrophages were supplemented with either docosahexaenoic acid (DHA) or arachidonic acid (AA) and analyzed for receptor expression and microdomain localization in context of TLR stimulation. Results and Conclusions: Our analyses showed that receptor levels and microdomain localization were unchanged by PUFA supplementation. The TLR2 pathway, in contrast to the TLR4 signaling cascade, is not affected by exogenous PUFA at the membrane level. [ABSTRACT FROM AUTHOR]

Background: Toll-like receptors (TLRs) are the major pattern recognition receptors that mediate sensing of a wide range of microorganisms. TLR2 forms heterodimers with either TLR1 or TLR6, broadening its ligand diversity against pathogens. TLR1, TLR2 and TLR6 have been implicated in the recognition of Candida albicans, an opportunistic fungal pathogen that colonizes the gastrointestinal tract. In this study, we explored whether the deficiency in TLR1, TLR2 or TLR6 impacts C. albicans colonization and inflammation-associated colonic injury in the dextran sulfate sodium (DSS)-induced colitis in mice. Results: DSS treatment and C. albicans challenge induced greater weight loss, worse clinical signs of inflammation, higher histopathologic scores, and increased mortality rates in TLR1-/- and TLR2-/- mice when compared to TLR6-/- and wild-type mice. The number of C. albicans colonies in the stomach, colon and feces was decreased in TLR6-/- mice as compared to TLR2-/-, TLR1-/- and wild-type mice. Interestingly, the population of E. coli in colonic luminal contents, intestinal permeability to FITC-dextran and cytokine expression were significantly increased in TLR1-/- and TLR2-/- mice, while they were decreased in TLR6-/- mice. Conclusion: In contrast to TLR6, both TLR1 and TLR2 deficiencies increased intestinal inflammation, and the overgrowth of C. albicans and E. coli populations in the colitis model, suggesting the involvement of TLR1 and TLR2 in epithelial homeostasis, and a role of TLR6 in increasing intestinal inflammation in response to pathogen-sensing. [ABSTRACT FROM AUTHOR]

TLR2 heterodimers with TLR1 or TLR6 recognize distinct pathogen-associated molecules such as tri- and di-acylated lipopeptides. The activated TLR2 heterodimers recruit Toll-IL-1R domain- (TIR-) containing adapter proteins, TIRAP and MyD88, through the receptor TIR domains. Molecular recognition mechanisms responsible for agonist-driven, TIR domain-mediated receptor-adapter interactions as well as the structure of resultant signaling complexes remain unknown. We previously reported that the cell-permeable peptide derived from helix D of TLR2 TIR (2R9) specifically binds TIRAP in vitro and in cells and thereby inhibits TIRAP-dependent TLR signaling. This study demonstrates that cell-permeable peptides from D helix of TLR1 or TLR6, peptides 1R9 and 6R9 respectively, inhibit signaling mediated by cognate TLR2 co-receptors. Interestingly, 1R9 and 6R9 bind different TLR2 adapters, as they selectively bind MyD88 and TIRAP TIR, respectively. Both peptides block the agonist-induced co-immunoprecipitation (co-IP) of TLR2 with TIRAP or MyD88, but not TLR2 co-IP with co-receptors. Our data suggest that D helices of TLR1 and TLR6 TIR domains are adapter recruitment sites in both co-receptors; yet the sites recruit different adapters. The D helix in TLR1 is the MyD88 docking site, whereas in TLR6 this site recruits TIRAP. [ABSTRACT FROM AUTHOR]

Abstract: Placentae from newborns with congenital human cytomegalovirus (HCMV) infection often display shallow implantation, chronic villitis and disruptions of the syncytiotrophoblast. Little is known about how HCMV infection induces inflammation in the placenta and loss of the trophoblast. We propose that the inflammation is initiated with innate defense responses of mature syncytiotrophoblast (ST) to virus. Previously we have shown that ultraviolet irradiation-inactivated (UV-) HCMV interacts with toll-like receptor 2 (TLR2) on primary placental cytotrophoblasts (CT) differentiated into ST-like cells thereby stimulating the release of tumor necrosis factor alpha (TNFα) and inducing apoptosis of neighboring cells (Chan et al, J. Pathol. 210: 111, 2006). We now determine whether known co-factors of the interaction of HCMV and TLR2 (TLR1 and CD14) bind to UV-HCMV to stimulate expression of TNFα and apoptosis in ST-like cells but not CT. We show that CT both fail to express detectable TLR1 and express much less CD14 than ST and that ST express CD14 but not TLR1 both in vivo and in cultured cells. The interaction of UV-HCMV and HCMV with CD14 on the surface of ST-like cells increases TNFα expression and induces apoptosis in the population. Antibody to CD14 also inhibits infectious HCMV induction of HCMV immediate early (HCMV IE) expressing ST-like cells. We conclude that primary villous CT express low levels of CD14 and no TLR1 but that ST strongly expresses CD14 which acts upstream of TLR2 to collect even transcriptionally inactive virus particles to stimulate TNFα expression and villous trophoblast damage. [Copyright &y& Elsevier]

Abstract: Toll-like receptors (TLRs) are key sensors of pathogen-associated molecular patterns (PAMPs). Their role in immunity is difficult to examine in species of veterinary interest, due to restricted access to the knockout technology and TLR-specific antibodies. An alternative approach is to generate cell lines transfected with various TLRs and to examine the recognition of PAMPs or relevant bacteria. In this report, we examined whether recognition of various PAMPs and mastitis-causing bacteria is achieved by transfection of recombinant bovine TLR2 (boTLR2). Therefore, human embryonic kidney (HEK) 293 cells were transfected by whole boTLR2. A clonal analysis of stably transfected cells disclosed variable recognition of several putative TLR2 agonists although expressing similar amounts of the transgene and endogenous TLR6. One clone (clone 25) reacted by copious interleukin-8 (IL-8) production to several stimulants of TLR2 such as di-palmitoylated cysteyl-seryl-lysyl-lysyl-lysyl-lysine (Pam2), a biochemical preparation of lipoteichoic acid from Staphylococcus aureus, a commercial preparation of peptidoglycan from S. aureus, and heat-killed Listeria monocytogenes (HKLM). TLR2-dependent induction of IL-8 release was stronger in medium containing human serum albumin than in medium containing fetal calf serum. Clone 25 cells responded to high concentrations of S. aureus and to Escherichia coli causing mastitis, but not to Streptococcus uberis and to Streptococcus agalactiae which also cause mastitis. Stimulation by S. aureus was relatively weak when compared (i) with stimulation of the same cells by HKLM and PAMPs derived from S. aureus, (ii) with a clone stably transfected with TLR4 and MD-2 and stimulated by E. coli causing mastitis, and (iii) with interferon-γ-costimulated bovine macrophages stimulated by S. aureus and S. agalactiae. Thus, clone 25 is suitable for studying the interaction of putative TLR2 agonists with bovine TLR2-transfected cells, provides a cell to search for TLR2-specific antibodies, and is a tool for studying the interaction of TLR2 with bacteria causing disease, e.g. mastitis, in cattle. [Copyright &y& Elsevier]

The last decade has revealed interesting insights into the initiation and pathophysiology of the innate immune system. Toll-like receptors are of key importance for this process and they are a family of receptors expressed mainly on leukocytes that recognize a variety of microbial products derived from bacteria, viruses, protozoa and fungi. As key players of innate immunity, TLRs and downstream signalling components are important target candidates for drug development. In this review, we focus on TLR2, which recognizes bacterial lipopeptide. TLR2 forms dimers with TLR1 or TLR6. The TLR2/TLR1 dimer recognizes triacylated lipopeptides, whilst the TLR2/TLR6 dimer recognizes diacylated lipopeptides. TLR2 has been implicated in several auto-immune and inflammatory conditions, and its role in disease pathogenesis has been supported by numerous reports of TLR2 polymorphisms in humans linked to disease. Here we discuss the potential of TLR2 as a drug target in autoimmune and inflammatory disease. [ABSTRACT FROM AUTHOR]

Toll-like receptor 2 (TLR2) responses are involved in various inflammatory immune disorders. Phloretin is a naturally occurring dietary flavonoid that is abundant in fruit. Here, we investigated whether the anti-inflammatory activity of phloretin is mediated through TLR2 pathways, and whether phloretin acts as an inhibitor of TLR2/1 heterodimerization using the TLR2/1 agonist Pam3CSK4. We tested the effects of phloretin on tumor necrosis factor (TNF)-α production induced by various TLRs using known TLR-specific agonists. Phloretin significantly inhibited Pam3CSK4-induced TRL2/1 signaling in Raw264.7 cells compared to TLR signaling induced by the other agonists tested. Therefore, we further tested the effects of phloretin in human embryonic kidney (HEK) 293-hTLR2 cells induced by Pam3CSK4, and confirmed that phloretin has comparable inhibition of TLR2/1 heterodimerization to that induced by the known TLR2 inhibitor CU-CPT22. Moreover, phloretin reduced the secretion of the inflammatory cytokines TNF-α and interleukin (IL)-8 in Pam3CSK4-induced HEK293-hTLR2 cells, whereas it did not significantly reduce these cytokines under Pam2CSK4-induced activation. Western blot results showed that phloretin significantly suppressed Pam3CSK4-induced TLR2 and NF-κB p65 expression. The molecular interactions between phloretin and TLR2 were investigated using bio-layer interferometry and in silico docking. Phloretin bound to TLR2 with micromolar binding affinity, and we proposed a binding model of phloretin at the TLR2–TLR1 interface. Overall, we confirmed that phloretin inhibits the heterodimerization of TLR2/1, highlighting TLR2 signaling as a therapeutic target for treating TLR2-mediated inflammatory immune diseases. [ABSTRACT FROM AUTHOR]