Increased Toll-like Receptors Expression Research Articles

Clinical and Oncological Impact of the Toll-like Receptor-3 and -4 in Esophageal and Gastro-esophageal Junction Adenocarcinoma.

Esophageal and gastro-esophageal junction cancer is a major cause of cancer-related mortality, with poor prognosis. Toll-like receptors (TLRs) play a significant role in the innate immune system; their increased expression has been associated with esophageal adenocarcinoma. This study aimed to determine the association between TLR-3 and TLR-4 expression with clinical and oncological outcomes of patients that underwent esophagectomy for cancer. This is a retrospective analysis of prospectively collected data from consecutive patients within a 2-year period. Primary endpoints of the study were the assessment of the expression of TLR-3 and TLR-4 in primary tumors as well as in metastatic lymph nodes. Secondary endpoints were the correlation of TLR-3 and TLR-4 values with the clinical, pathological, and oncological outcomes. A significantly higher expression of TLR-3 and TLR-4 in primary tumors and metastatic-lymph nodes was observed. There was a significant association between TLR-3 expression and T-stage, as well as TLR-4 expression and grade of differentiation in the primary site. Additionally, metastatic-lymph node TLR-4 expression was significantly correlated with N-stage. A strong correlation between TLR-4 expression and overall or progression-free survival rates was detected. This study found a significantly increased TLR expression in malignant tissue/metastatic lymph nodes, as well as a significant positive correlation between TLRs and worse clinical outcomes. TLRs have a pivotal role in the inflammation pathway in the esophagus and during esophageal carcinogenesis. This study highlights the need for further investigation into TLR-mediated signaling pathways and their potential role as diagnostic and therapeutic targets.

Intrarenal Toll-like receptor 4 and Toll-like receptor 2 expression correlates with injury in antineutrophil cytoplasmic antibody-associated vasculitis

In antineutrophil cytoplasmic antibody-associated vasculitis (AAV), Toll-like receptors (TLRs) may be engaged by infection-associated patterns and by endogenous danger signals, linking infection and innate inflammation with this autoimmune disease. This study examined intrarenal TLR2, TLR4, and TLR9 expression and renal injury in AAV, testing the hypothesis that increased TLR expression correlates with renal injury. Patients with AAV exhibited both glomerular and tubulointerstitial expression of TLR2, TLR4, and TLR9, with TLR4 being the most prominent in both compartments. Glomerular TLR4 expression correlated with glomerular segmental necrosis and cellular crescents, with TLR2 expression correlating with glomerular segmental necrosis. The extent and intensity of glomerular and tubulointerstitial TLR4 expression and the intensity of glomerular TLR2 expression inversely correlated with the presenting estimated glomerular filtration rate. Although myeloid cells within the kidney expressed TLR2, TLR4, and TLR9, TLR2 and TLR4 colocalized with endothelial cells and podocytes, whereas TLR9 was expressed predominantly by podocytes. The functional relevance of intrarenal TLR expression was further supported by the colocalization of TLRs with their endogenous ligands high-mobility group box 1 and fibrinogen. Therefore, in AAV, the extent of intrarenal TLR4 and TLR2 expression and their correlation with renal injury indicates that TLR4, and to a lesser degree TLR2, may be potential therapeutic targets in this disease.

Expression of Toll-Like receptors in metabolic syndrome: A systematic review

Introduction: Toll-Like Receptors (TLRs) of innate immune system have documented roles in the pathogenesis of metabolic disorders. This study aims to systematically review the expression of TLRs on metabolic syndrome (MetS). Materials and methods: We systematically searched PubMed/Medline, ISI web of Science, Scopus, Google Scholar, EMBASE, and OVID databases until February 2017. The terms ‘‘Metabolic Syndrome OR ‘‘Mets AND ‘‘Toll like receptor OR ‘‘Toll like OR ‘‘TLRs OR ‘‘TLR were used. “Expression” advertently was not used in our search and was considered in the selection process. Three steps for selecting the articles and then their qualification were conducted. Results: First, 1373 articles were found in the international databases. After removing duplicates, 963 papers remained and after two steps of selection, this number reached 410 and then 27, respectively. After full text screening and qualifying processes, we finally included 13 articles consisting of five animal and eight human studies. All human studies reported overexpression of TLRs (types 2, 4, 5, 9) in MetS, and most animal studies documented an increased TLRs expression. Conclusion: This systematic review provides evidence for the relation of innate immune system with MetS. Its findings regarding overexpression of special TLRs (e.g. types 2, 4, 5, 9) in MetS and their basic mechanisms and clinical implications might be investigated in further studies.

The Expression of Toll-like Receptors in Normal Human and Murine Gastrointestinal Organs and the Effect of Microbiome and Cancer.

Toll-like receptors (TLRs) are innate immune receptors expressed in all parts of the alimentary tract. However, analyses comparing expression in different segments and data on germ-free animals are lacking. Alimentary tract cancers show increased TLR expression. According to the field effect concept, carcinogenetic factors induce subtle cancer predisposing alterations in the whole organ. We studied TLR1 to TLR9 expression in all segments of the alimentary tract from cancer patients’ tumor-adjacent normal mucosa, healthy organ donors, and conventional and germ-free mice by using immunohistochemistry and quantitative PCR. All TLRs were expressed in all segments of the alimentary tract. Expression was most intensive in the small intestine in humans and conventional mice, but germ-free mice showed less expression in the small intestine. TLR expression levels were similar in cancer patients and organ donors. We provide systematic baseline data on the TLR expression in the alimentary tract. Normal epithelium adjacent to tumor seems to have similar TLR expression compared with healthy tissues suggesting absence of any field effect in TLR expression. Accordingly, specimens from cancer patients’ normal tumor-adjacent tissue can be used as control tissues in immunohistochemical TLR studies in gastrointestinal cancer.

Expression of Toll-Like Receptors in Chronic Histiocytic Intervillositis of the Placenta

Chronic histiocytic intervillositis of the placenta (CHI) shows monocytic/histiocytic infiltration of the intervillous space. Placental malaria has a CHI-like histopathology and induces an aberrant expression of Toll-like receptors (TLR) 3, 7–9. We hypothesized that, similar to placental malaria, CHI could be associated with increased TLR expression. TLR1-10 and other inflammation-associated factors were analyzed by real-time PCR and immunohistochemistry. A total of 31 formalin-fixed and paraffin–embedded placenta samples were evaluated: CHI (n = 9), and for control purposes, villitis of unknown etiology (VUE, n = 8) and placentas without inflammation (n = 14). CHI shows increased expression of monocytic TLR1, a receptor which is involved in bacterial lipopolysaccharide (LPS)-induced inflammation. This could indicate a TLR1-mediated immune mechanism in the placenta (e.g. triggered by transient, clinically inapparent maternal bacteraemia) which leads to massive monocytic/histiocytic accumulation in the intervillous space. The increased expression of TLR1 with no increased expression of TLR3 and TLR7-9 is different from that in malaria.

Mechanical Injury to Human Intervertebral Discs and Isolated Cells Initiates Events Implicated in Degeneration and Pain

Introduction Painful degenerating intact human intervertebral discs (IVDs) produce elevated levels of Toll-like receptors (TLRs), cytokines, and neuropeptides but events regulating their expression are poorly understood. Mechanical overload has been proposed as one potential initiating mechanism. The aim of this study was to investigate the cellular responses in IVDs and isolated disc cells exposed to mechanical overload or strain. Methods Lumbar spine segments were harvested from consenting donors via the Transplant Quebec organ donation program in Montreal, Quebec, Canada. A total of nine discs from six donors were used in this study. Intact IVDs were prepared and cells isolated using a standard technique. Intact discs with cartilaginous endplates were loaded with a single ramp compression peaking at either approximately 0.2 MPa (noninjurious) or about 1.5 MPa (injurious) stress applied at a rate of 30% strain per second. Injurious compression protocol consistently yields endplate fracture. Discs were immediately put in low serum containing media after loading. For isolated cell experiments, 2 × 105 nucleus pulposus (NP) and annulus fibrosus (AF) cells were seeded on flexible or static silicone dishes. The flexible dishes were exposed to a 20% magnitude cyclic mechanical strain at 0.0001 Hz was applied to the cultures for 8 h/d over 2 days. Conditioned media was collected and RNA was isolated. Quantitative RT-PCR was performed to assess TLR, NGF, and TNF gene expression. Conditioned media from intact discs and isolated cells was applied to PC12 cells and neurite outgrowth was assessed. Commercially available cytokine arrays were used to investigate protein levels of cytokines released from intact discs and isolated cells. Results Elevated levels of proteoglycan, inflammatory cytokines, and pain mediators were released from intact discs exposed to injurious loading. The highest levels were found 3 days postinjury and the conditioned media caused significantly induced neurite outgrowth in PC12 cells compared with that of the control group. About 50% of the cells in the IVDs died as a result of the inflicted trauma. Isolated NP and AF cells were exposed to a high-magnitude strain at low frequency to preserve cell attachments and maintain cell viability. The protocol was applied to evaluate if the adverse mechanical stimulation of the cells or the induced cell death caused by the injurious loading of the intact IVDs was responsible for the increased expression of inflammatory cytokines and pain mediators. Our data showed that high-magnitude low-frequency strain is sufficient to induce expression inflammatory cytokines and pain mediators in the absence of cell death. We also found a small but significant upregulation of TLR 2 and 4 in both NP and AF cells. Conclusion Cell death and cytokine production combined with loss of glycosaminoglycan indicate that mechanical injury to intact IVDs and isolated cells initiates cellular processes leading to disc degeneration. Once the proteoglycan content in the matrix has been degraded, elevated levels of NGF could lead to neuronal ingrowth directly causing pain. Increased TLR expression induced by high strain may prime cells toward a degenerate phenotype and could be a novel therapeutic target for degenerative disc disease.

Effect of increased glucose on the expression of TLRs in human macrophages: potential mechanism of chronic inflammation in diabetes

Diabetic patients suffer from a chronic inflammation regulated by macrophages. M1 and M2 represent two major directions of macrophage functional polarisation. Toll-like receptors (TLR)-mediated response to exogenous and endogenous factors results in pro-inflammatory activation of macrophages. Increased TLR expression in monocytes is associated with the diabetic inflammation and complications. The aim of our study was to examine how elevated glucose levels affect expression of TLRs in M1 and M2. Monocytes were isolated from healthy donors and cultured in serum-free medium in the presence of 5mM or 25mM glucose for 6 days. M1 and M2 differentiation was driven by IFN-γ and IL-4. Quantification of TLR mRNA expression was performed by RT-PCR and demonstrated that mRNA of TLR1, 2, 4, 6 and 8, but not TLR5 and 9, were expressed in M1 and M2. All identified TLRs were expressed on higher levels in M1 compared to M2 in low and high glucose conditions. Increased glucose had most pronounced stimulatory effect on the expression of TLR2 and less on TLR6. In individual M1 cultures high glucose stimulated up to 8-fold increase of TLR2 and up to 28% increased of TLR6 expression. In M2, TLR2 expression was up to 6-fold higher in the presence to high glucose. High glucose had suppressive effect on the expression of TLR4 (in 5 of 8 donors up to 65%) in M1 and M2. We concluded that glucose regulates TLR2, 6 and 4 expression in a donor-specific way. This may explain the individual development of inflammation-mediated complications in diabetes.

Toll-like receptor expression and signaling in human diabetic wounds.

To examine the contribution of toll-like receptors (TLRs) expression and activation to the prolonged inflammation often seen in human diabetic wounds. Debridement wound tissue was collected from diabetic patients with informed consent. Total RNA and protein were isolated and subjected to real-time polymerase chain reaction and Western blot analyses. TLR1, 2, 4, and 6 mRNA expressions were increased significantly in wounds of diabetic patients compared with non-diabetic wounds (P < 0.05). MyD88 protein expression was significantly increased in diabetic wounds compared to non-diabetic wounds. Interleukin-1beta, tumor necrosis factor-alpha concentration nuclear factor-kappa B activation, and thiobarbituric acid reactive substances were increased in diabetic wounds compared to non-diabetic wounds (P < 0.01). Collectively, our novel findings show that increased TLR expression, signaling, and activation may contribute to the hyper inflammation in the human diabetic wounds.

Toll‐like receptor expression in severe asthma with chronic rhinosinusitis

We have in an epidemiological study identified a group of individuals with multiple asthma symptoms (MSA) that reflect a more severe and uncontrolled disease. An altered innate immunity and adaptive immunity, and effects of microorganisms may play a role in the development of both CRS and asthma. The innate immune system use Toll-like receptors (TLRs) to recognize microbes and activate defense mechanisms within minutes of microbial invasion which is followed by an antigen-specific response by the adaptive immune system. Thus, innate and adaptive immune cells are sequentially activated and reciprocally regulate one another. Glycogen synthase kinase-3β (GSK3β) has been demonstrated as a regulator of both innate and adaptive immunity. GSK3β was shown to modulate inflammatory responses through TLR-mediated production of pro-inflammatory cytokines and inactivation of GSK3β (phosphorylated GSK3β) lead to a reduced IL-12 production, which was suggested to skew the balance towards a Th2 response. To determine the degree of expression of TLRs 2, 4, 7 and 9 on monocytes as well phGSK3β using flow cytometry. We hypothesize that the co-existence of CRS in patients with asthma and especially patients with MSA has an increased TLR expression involved in the innate immune system. Participants were selected from an epidemiological cohort, the West Sweden Asthma Study. Clinical parameters as well as fresh peripheral blood cells were obtained from one group of non-asthmatic subjects with CRS (CRS) and four different groups of asthmatics: 7 subjects with MSA (MSA), 7 subjects with other asthma (OA), 7 subjects with MSA and CRS (MSA/CRS) and 9 subjects with OA and CRS (OA/CRS). These five groups were compared to a control group consisting of 10 healthy subjects without asthma or CRS. Individuals with MSA or CRS only, showed significantly increased TLR2, TLR7 and TLR9 expression (rMFI) on CD14+ monocytes compared to controls as well as the expression of phGSK3β and CD14. Individuals in the combined MSA/CRS group showed increased expression of CD14 and TLR2, but increased expression of TLR4 was only found in the CRS group. The upregulated expression of TLRs in the MSA group compared to control group suggest a higher susceptibility towards an altered immune response that might reflect the degree of severity. Furthermore, the increased phosphorylation of GSK3β may indicate a switch in the immune response from a pro-inflammatory to a dysregulated Th2 response.

Role of human Toll‐like receptors in naturally occurring influenza A infections

BackgroundWe investigated the roles of Toll‐like receptors (TLRs) in naturally occurring influenza.MethodsA prospective, case – control study was conducted. Adults hospitalized with virologically confirmed influenza A infections (onset <48 hours, before treatment) were compared with age‐/gender‐matched controls. TLRs (2, 3, 4, 7, 8, 9) expression in monocytes and dendritic cells (DCs – total, myeloid, plasmacytoid) was quantitated using flow cytometry. Gene expression of RLRs (RIG‐1, MDA‐5) was evaluated using real‐time PCR. Concomitant signaling molecules expression, plasma cytokine/chemokine concentrations, and respiratory tract viral loads were measured. PBMCs were cultured and stimulated ex vivo with TLR‐specific ligands for cytokine responses.ResultsForty two patients with influenza (24 A/H3N2, 18 A/H1N1pdm09) and 20 controls were studied. Patients' mean age was 68 ± 16 years; 81% had respiratory/cardiovascular complications. There were increased cellular expressions of TLR9, TLR8, TLR3, and TLR7 during influenza; TLR2 and TLR4 were suppressed. Results were similar for both virus strains. Higher TLR expression levels at presentation significantly correlated with lower viral loads (Spearman's rho: −0·46 to −0·69 for TLR9, TLR8, and TLR3; P‐values <0·05). Multivariate regression models (adjusted for age, comorbidity, disease severity, time from onset) confirmed their independent associations. Increased signaling molecules (phospho‐MAPKs, IκB) and inflammatory cytokines (IL‐6, sTNFR‐1, CCL2/MCP‐1; CXCL10/IP‐10, IFN‐γ) correlated with increased TLR expression. RLRs were upregulated simultaneously. PBMCs of patients with influenza showed significant, dynamic changes in their cytokine responses upon TLR stimulation, compared with controls.ConclusionsOur results suggest that TLRs play an important role in early, innate viral inhibition in naturally occurring influenza. Inflammatory cytokine responses are concomitantly induced. These findings support investigation of TLR targeting as a novel intervention approach for prophylaxis against influenza.

Expression of Toll-like receptors and their detection of nuclear self-antigen leading to immune activation in JSLE

Toll-like receptors (TLRs) essential in the functioning of the immune system have been implicated in the development of autoimmunity. TLR3, 7, 8 and 9 are capable of recognizing nucleic autoantigens typical of SLE. Their expression correlates positively with disease activity in adult-onset SLE. This study aimed to determine the role of TLRs in JSLE and whether apoptotic neutrophils are a source of nuclear autoantigen being detected through TLR3, 7, 8 and 9, leading to an inflammatory response. TLR3, 7, 8 and 9 mRNA and protein expression were measured in peripheral blood mononuclear cells (PBMCs) in JSLE patients compared with JIA and non-inflammatory controls. Activation of the TLRs by JSLE serum-induced apoptotic neutrophils was detected by measuring IFN-α mRNA and protein expression, and confirmed using myeloid differentiation factor 88 (MyD88) and TIR domain-containing adapter-inducing IFN-β (TRIF) inhibitors. JSLE patients have increased TLR3, 8 and 9 mRNA and protein expression compared with controls (P < 0.05). Incubation of PBMCs with apoptotic neutrophils demonstrated a dose-response relationship for IFN-α mRNA expression. Inhibition of TLR signalling by blocking MyD88 and TRIF signalling decreased IFN-α mRNA expression in PBMCs incubated with apoptotic neutrophils (P < 0.05). This study demonstrated significantly increased TLR expression in JSLE compared with controls. Our data indicate that apoptotic neutrophils trigger TLR activation through their presentation of autoantigens. The role of TLRs in this inflammatory response was demonstrated by a dose-response relationship to apoptotic neutrophil concentration and confirmed by a decrease in IFN-α production after inhibition of TLR signalling.

Increased Expression of Toll-Like Receptors by Monocytes and Natural Killer Cells in ANCA-Associated Vasculitis

IntroductionToll-like receptors (TLRs) are a family of receptors that sense pathogen associated patterns such as bacterial cell wall proteins. Bacterial infections are associated with anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV). Here, we assessed the expression of TLRs 2, 4, and 9 by peripheral blood leukocytes from patients with AAV, and investigated TLR mediated responses ex vivo.MethodsExpression of TLRs was determined in 38 AAV patients (32 remission, 6 active disease), and 20 healthy controls (HC). Membrane expression of TLRs 2, 4, and 9, and intracellular expression of TLR9 by B lymphocytes, T lymphocytes, NK cells, monocytes and granulocytes was assessed using 9-color flowcytometry. Whole blood from 13 patients and 7 HC was stimulated ex vivo with TLR 2, 4 and 9 ligands and production of cytokines was analyzed.ResultsIn patients, we observed increased proportions of TLR expressing NK cells. Furthermore, patient monocytes expressed higher levels of TLR2 compared to HC, and in a subset of patients an increased proportion of TLR4+ monocytes was observed. Monocytes from nasal carriers of Staphylococcus aureus expressed increased levels of intracellular TLR9. Membrane expression of TLRs by B lymphocytes, T lymphocytes, and granulocytes was comparable between AAV patients and HC. Patients with active disease did not show differential TLR expression compared to patients in remission. Ex vivo responses to TLR ligands did not differ significantly between patients and HC.ConclusionsIn AAV, monocytes and NK cells display increased TLR expression. Increased TLR expression by these leukocytes, probably resulting from increased activation, could play a role in disease (re)activation.

Increased Expression of Toll-like Receptors (TLR) 2, 4 and 5 in Gastric Dysplasia

TLRs are important innate immunity receptors. Even though TLR2, 4 and 5 appear to be important for Helicobacter pylori (HP) recognition, their role in the evolution of gastritis to more advanced lesions is still unknown. To compare the expression of TLR2, 4 and 5 in normal gastric mucosa, HP+ gastritis, intestinal metaplasia, dysplasia and adenocarcinoma. Immunohistochemistry for TLR2, 4 and 5 was performed with anti-TLR2-TLR4-TLR5 antibodies in 117 histological samples of normal gastric mucosa (n = 22), HP+ gastritis (n = 20), intestinal metaplasia (n = 33), dysplasia (mucosectomy specimens, n = 20) and intestinal type adenocarcinoma (surgery specimens,n = 22); quantification of expression was performed independently by two pathologists taking into account the percentage of positive epithelial cells and the degree of expression (zero to three score). A statistically significant trend for progressive increase of TLRs expression from normal mucosa to gastric dysplasia was found (mean expression: normal mucosa 0.1; gastritis 1.0; metaplasia 2.2; dysplasia 2.8, p < 0.01). All dysplasia samples presented more than 90% positive epithelial cells with strong expression (2.8;95%CI2.7-3). There was less TLRs expression in carcinomas (TLR2:1.0; TLR4:2.0 and TLR5:1.2, p < 0.05) when compared with dysplasia, with TLR4 being more expressed than TLR2 and 5 in these lesions (p = 0.03). A score of all markers' expression of eight leads to a low (4%) false positive rate in patients with precancerous conditions. Progression of gastric lesions associated with gastric carcinogenesis is associated with increased TLRs expression. Gastric dysplasia presents a high level of TLRs expression, suggesting that these receptors may play a role in adenocarcinoma development.

Up-regulation of cell surface Toll-like receptors on circulating γδ T-cells following burn injury

Burn injury is associated with profound inflammation and activation of the innate immune system involving γδ T-cells. Similarly, Toll-like receptors (TLR) are associated with activation of the innate immune response; however, it is unclear whether TLR expression is altered in γδ T-cells after major burn injury. To study this, male C57BL/6 mice were subjected to burn injury (25% TBSA) and 1 or 7 days thereafter, blood and spleen cells were isolated and subjected to FACs analysis for TLRs and other phenotypic markers (γδ TCR, αβ TCR, CD69, CD120b). A marked increase in the number of circulating γδ T-cells was observed at 24 h post-burn (14% vs. 4%) and a higher percentage of these cells expressed TLR-2. TLR-4 expression was also increased post-burn, but to a lesser degree. These changes in TLR expression were not associated with altered CD69 or CD120b expression in γδ T-cells. The mobilization of, and increased TLR expression in, γδ T-cells was transient, as phenotypic changes were not evident at 7 days post-burn or in γδ T-cells from the circulation or spleen. The increases in TLR expression were not observed in αβ T-cells after burn injury. In conclusion, 24 h after burn injury mobilization of γδ T-cells with increased TLR expression was observed. This finding suggests that this unique T-cell population is critical in the innate immune response to injury, possibly through the recognition of danger signals by TLRs.

Higher Monocyte Expression of TLR2 and TLR4, and Enhanced Pro-inflammatory Synergy of TLR2 with NOD2 Stimulation in Sarcoidosis

Sarcoidosis is an inflammatory disease of unknown etiology. However, an infectious cause has been proposed suggesting a role for pattern-recognition receptors, such as Toll-like receptors (TLRs) and nucleotide-binding domain, leucin-rich repeat containing family proteins (NLRs), in the pathogenesis. Our aim was to investigate whether differences in TLR2 and TLR4 expression, and the response to TLR2, TLR4, and NOD2 stimulation, are associated with sarcoidosis. Blood mononuclear cells from sarcoidosis patients (n = 24) and healthy subjects (n = 19) were incubated with the TLR2 ligands PGN and Pam3CSK4, the TLR4 ligand LPS, the NOD2 ligand MDP, or medium alone. After 16 h, monocyte TLR2 and TLR4 expression and cytokine secretion, including TNFalpha, IL-1 beta, IL-6, IL-8, IL-10, and IL-12p70, were measured using flow cytometry and cytometric bead array. TLR2 and TLR4 expression at baseline was significantly higher in patients. Combined TLR2 and NOD2 stimulation induced a four-fold higher secretion of TNFalpha and a 13-fold higher secretion of IL-1 beta in patients. Additionally, there was a synergistic effect of TLR2 with NOD2 stimulation on induction of IL-1 beta in patients, whereas IL-10 was synergistically induced in healthy subjects. Increased TLR expression and enhanced secretion of pro-inflammatory cytokines after combined TLR2 and NOD2 stimulation may be related to the pathogenesis of sarcoidosis.

Immunohistochemical localization of Toll‐like receptors 1–10 in periodontitis

In periodontitis, bacteria and pathogen-associated molecular patterns are sensed by Toll-like receptors (TLRs), which initiate intracellular signaling cascades that may lead to host inflammation. In this study, the expression and distribution of TLRs (TLR-1 to TLR-10) were immunohistochemically detected in gingival epithelium and connective tissue. Immunohistochemistry was used for the localization of TLRs in gingival tissue samples from 10 patients with chronic periodontitis and 10 healthy controls; these samples were obtained during routine periodontal flap operations and during extraction operations performed for retained wisdom teeth, respectively. For the evaluation, epithelial layers were stratified to basal, spinous, and superficial layers, and the percentages of TLR-positive cells were determined. Both healthy and periodontitis gingival tissues expressed all TLRs except TLR-10. In patients with periodontitis, epithelial cells showed increased TLR expression towards the basal layer. Healthy controls showed more variable cellular TLR expression and distribution between the layers of epithelium. In the connective tissue, consistently higher TLR expression was found within the periodontitis group compared to the healthy group. For the first time, the cellular expression and distribution of TLR-1 to TLR-10 have been studied in periodontitis, indicating that TLR-1 to TLR-9 are differentially expressed both in connective tissue and epithelial layers. Except for TLR-7 and TLR-8, all the other TLRs showed statistically significant differences between patients with periodontitis and healthy controls, suggesting their involvement in the pathogenesis of periodontitis.

High glucose induces toll-like receptor expression in human monocytes: mechanism of activation.

OBJECTIVE—Hyperglycemia-induced inflammation is central in diabetes complications, and monocytes are important in orchestrating these effects. Toll-like receptors (TLRs) play a key role in innate immune responses and inflammation. However, there is a paucity of data examining the expression and activity of TLRs in hyperglycemic conditions. Thus, in the present study, we examined TLR2 and TLR4 mRNA and protein expression and mechanism of their induction in monocytic cells under high-glucose conditions.RESEARCH DESIGN AND METHODS—High glucose (15 mmol/l) significantly induced TLR2 and TLR4 expression in THP-1 cells in a time- and dose-dependent manner (P < 0.05). High glucose increased TLR expression, myeloid differentiation factor 88, interleukin-1 receptor–associated kinase-1, and nuclear factor-κB (NF-κB) p65-dependent activation in THP-1 cells. THP-1 cell data were further confirmed using freshly isolated monocytes from healthy human volunteers (n = 10).RESULTS—Pharmacological inhibition of protein kinase C (PKC) activity and NADPH oxidase significantly decreased TLR2 and TLR4 mRNA and protein (P < 0.05). Knocking down both TLR2 and TLR4 in the cells resulted in a 76% (P < 0.05) decrease in high-glucose–induced NF-κB activity, suggesting an additive effect. Furthermore, PKC-α knockdown decreased TLR2 by 61% (P < 0.05), whereas inhibition of PKC-δ decreased TLR4 under high glucose by 63% (P < 0.05). Small inhibitory RNA to p47Phox in THP-1 cells abrogated high-glucose–induced TLR2 and TLR4 expression. Additional studies revealed that PKC-α, PKC-δ, and p47Phox knockdown significantly abrogated high-glucose–induced NF-κB activation and inflammatory cytokine secretion.CONCLUSIONS—Collectively, these data suggest that high glucose induces TLR2 and -4 expression via PKC-α and PKC-δ, respectively, by stimulating NADPH oxidase in human monocytes.

Toll-like receptor expression and responsiveness are increased in viraemic HIV-1 infection

Toll-like receptors (TLR) are important in pathogen recognition and may play a role in HIV disease. We evaluated the effect of chronic untreated and treated HIV-1 infection on systemic TLR expression and TLR signalling. Two hundred HIV-infected and uninfected women from a Kenya cohort participated in the studies. TLR1 to TLR10 messenger RNA expression was determined by quantitative reverse transcriptase polymerase chain reaction in peripheral blood mononuclear cells (PBMC). TLR ligand responsiveness was determined in or using ex-vivo PBMC by cytokine production in culture supernatants. Chronic, untreated HIV-1 infection was significantly associated with increased mRNA expression of TLR6, TLR7, and TLR8 and when analysis was limited to those with advanced disease (CD4 cell count < 200 cells/ml) TLR2, TLR3, and TLR4 were additionally elevated. TLR expression correlated with the plasma HIV-RNA load, which was significant for TLR6 and TLR7. In vitro HIV single-stranded RNA alone could enhance TLR mRNA expression. PBMC of HIV-infected subjects also demonstrated profoundly increased proinflammatory responsiveness to TLR ligands, suggesting sensitization of TLR signalling in HIV. Finally, viral suppression by HAART was associated with a normalization of TLR levels. Together, these data indicate that chronic viraemic HIV-1 is associated with increased TLR expression and responsiveness, which may perpetuate innate immune dysfunction and activation that underlies HIV pathogenesis, and thus reveal potential new targets for therapy.

INCREASED TOLL LIKE RECEPTOR (TLR2 AND TLR4) EXPRESSION IN THE SMALL INTESTINAL MUCOSA OF CHILDREN WITH COELIAC DISEASE

Background: Besides the central role of the adaptive immunity, innate immune responses also play an important role in the development of coeliac disease. Recently it has been found that rod-shaped bacteria are frequently associated with the mucosa of coeliac disease patients but not with controls. Bacterial products are recognized by pattern recognition receptors (PRRs) like Toll-like receptors (TLRs), which are key regulators of the innate immune system. After ligand binding these receptors trigger the release of proinflammatory or chemotactic cytokines and chemokines, thus lowering the thereshold for the activation of gluten reactive CD4 + T cells in the lamina propria. Aim: The aim of this study was to characterise the expression of TLR2, TLR3 and TLR4 in intestinal biopsy samples from children with coeliac disease and controls. Methods: Duodenal biopsy samples were collected from 16 children with untreated coeliac disease [meadian age (range): 9 (4-15) yr] and 10 controls [10 (4-15) yr]. One sample from each patient was used for routine diagnostic purposes. The TLR2, TLR3 and TLR4 gene expression were evaluated by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Results: All coeliac patients had endomysium IgA positivity and subtotal villous atrophy in the small intestinal mucosa. All controls had normal histological finding. An eightfold increase of mRNA for TLR2 and fourfold for TLR4 were detected in the coeliac biopsy samples compared to controls (p < 0.05 for both comparisions). The expression of TLR3 gene was not significantly different. Summary: Increased TLR2 and TLR4 genes expression was found in children with coeliac disease. Conclusions: These data suggest that coeliac disease is associated with increased TLR expression in the intestinal mucosa, implying that alterations of innate immune system may contribute to the pathogenesis of this disorder.

Increased expression of toll-like receptor-2 and -4 on leukocytes from patients with sepsis.

The reduced responsiveness of monocytes or granulocytes toward endotoxin (endotoxin tolerance) during sepsis may depend on Toll-like receptors (TLR). The expression of TLR-2 and TLR-4 was measured on neutrophils (PMN) and monocytes from patients with sepsis (n = 21) or healthy controls (n = 12). Leukocytes (1 x 10/mL) were incubated at 37 degrees C with or without a TLR-4 (LPS 1 microg/mL) or a TLR-2 ligand (MALP-2 2 nM). Surface expression of TLR-2 and TLR-4 at 0, 4, and 16 h was determined in FACS after staining with specific antibodies. The release of IL-8 and TNF-alpha was measured by ELISA. Freshly isolated PMN from patients with sepsis exhibited significantly (P < 0.05) higher mean fluorescence for TLR-2 (78.0 +/- 18.6) and TLR-4 (11.4 +/- 2.3) than controls (12.8 +/- 2.2 and 2.3 +/- 0.4). Similarly, monocytes from patients exhibited higher TLR-2 and TLR-4 expression (300.8 +/- 40.6 and 92.7 +/- 12.1) than cells from controls (149.5 +/- 27.1 and 52.2 +/- 7.6). In patients with sepsis, expression of TLR-2 and TLR-4 on PMN increased during 16 h of incubation (106.2 +/- 22.1 and 34.5 +/- 5.3), whereas it remained unchanged in controls (19.3 +/- 6.1 and 5.4 +/- 1.9). Incubation with LPS or MALP-2 had no effect on TLR-4 or TLR-2 expression in cells from either controls or patients. Despite increased TLR expression in cells from patients with sepsis, the endotoxin-induced release of TNF-alpha and IL-8 was indistinguishable from that in controls. Therefore, the endotoxin tolerance seen in patients with sepsis does not depend solely on TLR-2 or TLR-4 expression, and other mechanisms must be involved.