Regulatory T cells and toll-like receptors: regulating the regulators

Role of toll-like receptor in the pathogenesis of oral cancer

Toll-like receptors are important molecules of innate immunity. They are known as pattern recognition receptors. They recognise certain molecules known as pathogen-associated molecular pattern on a pathogen and release chemicals that causes inflammation. Toll-like receptors (TLR) help in the removal of the infected cell and thus stop the spread of infection and are being studied for their association with cancer. Oral carcinoma has emerged as a major problem of our country today; it is found ranks first in men and third in women. Toll-like receptors have been implicated in the development of cancer. Certain polymorphisms in toll-like receptor can make a cell more susceptible to develop oral cancer. The identification of toll-like receptors and the different genotypes that are involved in the development of cancer can be utilised for using them as biomarkers of the disease. The study revealed that toll-like receptors like TLR7 and TLR5 are found to have a role in suppression of oral cancer while toll-like receptors like TLR4 and TLR2 are found to be associated with the progression of oral cancer. Toll-like receptors can turn out as important target molecules in the future in designing therapeutic strategies for oral cancer.

The Potential Preventive and Therapeutic Roles of NSAIDs in Prostate Cancer

Prostate cancer (PC) is the second most common type of cancer and the leading cause of death among men worldwide. Preventing the progression of cancer after treatments such as radical prostatectomy, radiation therapy, and hormone therapy is a major concern faced by prostate cancer patients. Inflammation, which can be caused by various factors such as infections, the microbiome, obesity and a high-fat diet, is considered to be the main cause of PC. Inflammatory cells are believed to play a crucial role in tumor progression. Therefore, nonsteroidal anti-inflammatory drugs along with their effects on the treatment of inflammation-related diseases, can prevent cancer and its progression by suppressing various inflammatory pathways. Recent evidence shows that nonsteroidal anti-inflammatory drugs are effective in the prevention and treatment of prostate cancer. In this review, we discuss the different pathways through which these drugs exert their potential preventive and therapeutic effects on prostate cancer.

Inflammatory perturbations in early life long-lastingly shape the transcriptome and TCR repertoire of the first wave of regulatory T cells

The first wave of Foxp3⁺ regulatory T cells (Tregs) generated in neonates is critical for the life-long prevention of autoimmunity. Although it is widely accepted that neonates are highly susceptible to infections, the impact of neonatal infections on this first wave of Tregs is completely unknown. Here, we challenged newborn Treg fate-mapping mice (Foxp3^eGFPCreERT2xROSA26^STOP-eYFP) with the Toll-like receptor (TLR) agonists LPS and poly I:C to mimic inflammatory perturbations upon neonatal bacterial or viral infections, respectively, and subsequently administrated tamoxifen during the first 8 days of life to selectively label the first wave of Tregs. Neonatally-tagged Tregs preferentially accumulated in non-lymphoid tissues (NLTs) when compared to secondary lymphoid organs (SLOs) irrespective of the treatment. One week post challenge, no differences in the frequency and phenotypes of neonatally-tagged Tregs were observed between challenged mice and untreated controls. However, upon aging, a decreased frequency of neonatally-tagged Tregs in both NLTs and SLOs was detected in challenged mice when compared to untreated controls. This decrease became significant 12 weeks post challenge, with no signs of altered Foxp3 stability. Remarkably, this late decrease in the frequency of neonatally-tagged Tregs only occurred when newborns were challenged, as treating 8-days-old mice with TLR agonists did not result in long-lasting alterations of the first wave of Tregs. Combined single-cell T cell receptor (TCR)-seq and RNA-seq revealed that neonatal inflammatory perturbations drastically diminished TCR diversity and long-lastingly altered the transcriptome of neonatally-tagged Tregs, exemplified by lower expression of Tigit, Foxp3, and Il2ra. Together, our data demonstrate that a single, transient encounter with a pathogen in early life can have long-lasting consequences for the first wave of Tregs, which might affect immunological tolerance, prevention of autoimmunity, and other non-canonical functions of tissue-resident Tregs in adulthood.

TLR2 Deficiency Exacerbates Imiquimod-Induced Psoriasis-Like Skin Inflammation through Decrease in Regulatory T Cells and Impaired IL-10 Production

Emerging evidence has demonstrated that Toll-like receptors (TLRs) are associated with autoimmune diseases. In this study, we investigated the role of TLR2 in psoriasis using imiquimod-induced psoriasis-like dermatitis. Although TLR2 signaling is known to play a critical role in the induction of proinflammatory cytokines by immune cells, such as dendritic cells (DCs), macrophages, and monocytes, TLR2 deficiency unexpectedly exacerbated psoriasiform skin inflammation. Importantly, messenger RNA (mRNA) levels of Foxp-3 and IL-10 in the lesional skin were significantly decreased in TLR2 KO mice compared with wild-type mice. Furthermore, flow cytometric analysis of the lymph nodes revealed that the frequency of regulatory T cells (Tregs) among CD4-positive cells was decreased. Notably, stimulation with Pam3CSK4 (TLR2/1 ligand) or Pam2CSK4 (TLR2/6 ligand) increased IL-10 production from Tregs and DCs and the proliferation of Tregs. Finally, adoptive transfer of Tregs from wild-type mice reduced imiquimod-induced skin inflammation in TLR2 KO mice. Taken together, our results suggest that TLR2 signaling directly enhances Treg proliferation and IL-10 production by Tregs and DCs, suppressing imiquimod-induced psoriasis-like skin inflammation. Enhancement of TLR2 signaling may be a new therapeutic strategy for psoriasis.

Ovarian Cancer Cells Promote Glycolysis Metabolism and TLR8-Mediated Metabolic Control of Human CD4+ T Cells

An immunosuppressive microenvironment is a major obstacle for successful tumor immunotherapy. Elucidating the regulatory mechanisms of energy metabolism and functionality in CD4⁺ T cells will provide insights for the development of novel immunotherapies for ovarian cancer (OC). An Agilent microarray was used to detect differences in gene expression between peripheral CD4⁺ T cells from five OC patients and those from five healthy controls. Functional pathway analysis was performed for differentially expressed genes. Gene expression profiles revealed significant differences in expression levels of 5,175 genes in peripheral CD4⁺ T cells from five patients with OC. Functional analysis indicated that the most significantly enriched pathways were metabolic pathways. Furthermore, eight glycolysis-related genes all showed significantly increased expression in peripheral CD4⁺ T cells of OC patients. Moreover, we established a coculture system of human CD4⁺ T cells with the OC cell line SKOV3, and then treated them with toll-like receptor 8 (TLR8) ligand ssRNA 40. Coculturing with SKOV3 cells could increase the expression of the eight glycolysis-related genes, promote glucose uptake and glycolysis in CD4⁺ T cells, induce the differentiation of CD4⁺ CD25⁺ Foxp3⁺ T cells, and enhance the suppression of naïve CD4⁺ T cells. Additionally, activated TLR8 signaling could mediate the reprogramming of glycolysis metabolism and function in CD4⁺ T cells. Overall, our study indicates that the SKOV3 coculture environment could regulate the glycolysis metabolism and function of CD4⁺ T cells, and also that TLR8 mediated the metabolic control of glycolysis in CD4⁺ T cells cocultured with SKOV3 cells. This provides a new direction for immunotherapy investigations in OC.

Expression and Functionality Study of 9 Toll-Like Receptors in 33 Drug-Naïve Non-Affective First Episode Psychosis Individuals: A 3-Month Study

Toll-like receptors (TLRs) are a pivotal component of the innate immune system that seem to have a role in the pathogenesis of psychosis. The purpose of this work was to compare the expression and functionality of 9 TLRs in three peripheral blood mononuclear cells (PBMCs) (monocytes, B cells, and T cells) between 33 drug-naïve first-episode psychosis (FEP) individuals and 26 healthy volunteers, at baseline and after 3-month of antipsychotic treatment. The expression of TLRs 1–9 were assessed by flow cytometry. For the assessment of the TLR functionality, cells collected in sodium heparin tubes were polyclonally stimulated for 18 h, with different agonists for human TLR1–9. The results of our study highlight the role that TLR5 and TLR8 might play in the pathophysiology of psychosis. We found a lower expression of these receptors in FEP individuals, regarding healthy volunteers at baseline and after 3-month of treatment on the three PBMCs subsets. Most TLRs showed a lower functionality (especially reduced intracellular levels of TNF-α) in patients than in healthy volunteers. These results, together with previous evidence, suggest that individuals with psychosis might show a pattern of TLR expression that differs from that of healthy volunteers, which could vary according to the intensity of immune/inflammatory response.

Use of Aspirin and Statins in Relation to Inflammation in Benign Prostate Tissue in the Placebo Arm of the Prostate Cancer Prevention Trial

Aspirin and statin use may lower the risk of advanced/fatal prostate cancer, possibly by reducing intraprostatic inflammation. To test this hypothesis, we investigated the association of aspirin and statin use with the presence and extent of intraprostatic inflammation, and the abundance of specific immune cell types, in benign prostate tissue from a subset of men from the placebo arm of the Prostate Cancer Prevention Trial. Men were classified as aspirin or statin users if they reported use at baseline or during the 7-year trial. Presence and extent of inflammation were assessed, and markers of specific immune cell types (CD4, CD8, FoxP3, CD68, and c-KIT) were scored, in slides from end-of-study prostate biopsies taken irrespective of clinical indication, per trial protocol. Logistic regression was used to estimate associations between medication use and inflammation measures, adjusted for potential confounders. Of 357 men included, 61% reported aspirin use and 32% reported statin use. Prevalence and extent of inflammation were not associated with medication use. However, aspirin users were more likely to have low FoxP3, a T regulatory cell marker [OR, 5.60; 95% confidence interval (CI), 1.16-27.07], and statin users were more likely to have low CD68, a macrophage marker (OR, 1.63; 95% CI, 0.81-3.27). If confirmed, these results suggest that these medications may alter the immune milieu of the prostate, which could potentially mediate effects of these medications on advanced/fatal prostate cancer risk.

Role of Toll like receptor in progression and suppression of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common type of head and neck squamous cell carcinoma and one of the multifactorial process that consists of most contributing factors such as tobacco smoking, chewing and alcohol consumption that altered the intracellular environment. Recent studies have shown relevance of Toll like receptor (TLR) associated with carcinogenesis. This review aim’s to explore that how TLR associates with progression and suppression of OSCC. This review is a classical review that has confined to articles published in the past 19 years (i.e. 2000-2019) and has summarized the perspective of the authors. 62 articles were reviewed and it was found that progression and suppression of OSCC is associated with different TLRs promoting tumor development and also inhibiting the progression of oral neoplasm. It was found that TLR2, TLR3, TLR4, TLR5, TLR7 and TLR9 are associated with tumor development i.e. in progression of OSCC, where as suppression of OSCC through TLR3 and TLR7. We authors would like to conclude that literature survey has indicated effective TLR’s against OSCC development and can be explored to investigate other TLRs that can be used for therapeutic purposes in near future.

Toll-like receptors: Important immune checkpoints in the regression of cervical intra-epithelial neoplasia 2

Toll-like receptors (TLRs) are innate immune defenders thought to be critical for the clearance of human papillomavirus (HPV) infections hence preventing the development of HPV-associated high-grade cervical intra-epithelial neoplasia (CIN2 or 3), a potential cervical cancer precursor. However, the role of TLRs in the regression of established cervical lesions, such as CIN2, is hindered by a lack of prospective design studies. Using SYBR green real-time PCR assays, we have examined the gene expression of TLR2, TLR3, TLR7, TLR8 and TLR9, in cytobrush collected endocervical cells of 63 women diagnosed with CIN2 at study entry (baseline) and followed over a 3-year period. Wilcoxon rank-sum test was used to examine the association between TLR expression levels, measured at baseline, and CIN2 outcome (regression vs. persistence/progression) over time. HPV genotyping was performed using Roche Linear Array Assay detecting 37 HPV types. Women with CIN2 regression showed significantly higher baseline levels of TLR2 (p = 0.006) and TLR7 (p = 0.007), as well as a non-significant trend for a higher TLR8 expression (p = 0.053) compared to women with CIN2 persistence/progression. Six women with CIN2 regression, who presented with an HR-HPV DNA-negative CIN2 lesion at study entry, had significantly higher baseline levels of TLR2 (p = 0.005), TLR7 (p = 0.013) and TLR8 (p = 0.012), compared to women with CIN2 persistence/progression, suggesting their role in clearance of HPV prior to clearance of the lesion. Our results confirm a key role of TLRs in regression of CIN2 and support the potential use of TLR-agonists for treatment of these lesions.

IL-17A-Producing Foxp3+ Regulatory T Cells and Human Diseases

CD4+Foxp3+ regulatory T (Treg) cells play major roles in immune homeostasis. While CD4+Foxp3+ Treg cells act to suppress other immune effector cells, there is growing evidence that they also produce pro-inflammatory cytokines, such as IL-17A, in inflammatory conditions. The pro-inflammatory cytokine milieu, toll-like receptor (TLR) signaling, and specific transcription factors are important for the production of IL-17A by CD4+Foxp3+ Treg cells. In particular, IL-17A-producing CD4+Foxp3+ Treg cells express RORγt, the T helper (Th) 17-specific transcription factor, in addition to Foxp3. IL-17A-producing CD4+Foxp3+ Treg cells are also involved in the pathogenesis of various diseases. Here we review the mechanisms underlying the induction of IL-17A-producing CD4+Foxp3+ Treg cells and the roles of these cells in human disease.

Heat shock proteins (HSPs) in the homeostasis of regulatory T cells (Tregs)

Heat shock proteins (HSPs) belong to the family of conservative polypeptides with a high homology of the primary structure. The uniqueness of this family lies in their ability to interact with a large number of different proteins and provide protection from cellular and environmental stress factors as molecular chaperones to keep protein homeostasis. While intracellular HSPs play a mainly protective role, extracellular or membrane-bound HSPs mediate immunological functions and immunomodulatory activity. In immune system are subsets of cells including regulatory T cells (Tregs) with suppressive functions. HSPs are implicated in the function of innate and adaptive immune systems, stimulate T lymphocyte proliferation and immunomodulatory functions, increase the effectiveness of cross-presentation of antigens, and induce the secretion of cytokines. HSPs are also important in the induction, proliferation, suppressive function, and cytokine production of Tregs, which are a subset of CD4+ T cells maintaining peripheral tolerance. Together HSPs and Tregs are potential tools for future clinical interventions in autoimmune disease.

The TLR7 agonist induces tumor regression both by promoting CD4⁺T cells proliferation and by reversing T regulatory cell-mediated suppression via dendritic cells

Treg-induced immunosuppression is now recognized as a key element in enabling tumors to escape immune-mediated destruction. Although topical TLR7 therapies such as imiquimod have been proved successful in the treatment of dermatological malignancy and a number of conditions beyond the FDA-approved indications, the mechanism behind the effect of TLR7 on effector T cell and Treg cell function in cancer immunosurveillance is still not well understood. Here, we found that Loxoribin, one of the TLR7 ligands, could inhibit tumor growth in xenograft models of colon cancer and lung cancer, and these anti-tumor effects of Loxoribin were mediated by promoting CD4⁺T cell proliferation and reversing Treg-mediated suppression via dendritic cells (DCs). However, deprivation of IL-6 using a neutralizing antibody abrogated the ability of Loxoribin-treated DCs, which reversed the Treg cell-mediated suppression. Furthermore, adoptive transfer of Loxoribin-treated DCs inhibited the tumor growth in vivo. Thus, this study links TLR7 signaling to the functional control of effector T cells and Treg cells and identifies Loxoribin as a new therapeutic strategy in cancer treatment, which may offer new opportunities to improve the outcome of cancer immunotherapy.

MALT1 is an intrinsic regulator of regulatory T cells

Regulatory T cells (Tregs) are crucial for the maintenance of immunological self-tolerance and their absence or dysfunction can lead to autoimmunity. However, the molecular pathways that govern Treg biology remain obscure. In this study, we show that the nuclear factor-κB signalling mediator mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is an important novel regulator of both Tregs originating in the thymus (‘natural’ or nTregs) and Tregs induced to differentiate from naive thymocyte helper (Th) cells in the periphery (‘induced’ or iTregs). Our examination of mice deficient for MALT1 revealed that these mutants have a reduced number of total Tregs. In young Malt1^−/− mice, nTregs are totally absent and iTreg are diminished in the periphery. Interestingly, total Treg numbers increase in older Malt1^−/− mice as well as in Malt1^−/− mice subjected to experimentally induced inflammation. iTregs isolated from WT and Malt1^−/− mice were indistinguishable with respect to their ability to suppress the activities of effector T cells, but Malt1^−/− iTregs expressed higher levels of Toll-like receptor (TLR) 2. Treatment of WT and Malt1^−/− Th cells in vitro with the TLR2 ligand Pam3Cys strongly enhanced the induction and proliferation of Malt1^−/− iTregs. Our data suggest that MALT1 supports nTreg development in the thymus but suppresses iTreg induction in the periphery during inflammation. Our data position MALT1 as a key molecule that contributes to immune tolerance at steady-state while facilitating immune reactivity under stress conditions.

Origin and functions of pro-inflammatory cytokine producing Foxp3+ regulatory T cells

CD4(+)CD25(+)Foxp3(+) regulatory cells (Tregs) are a special lineage of cells central in the maintenance of immune homeostasis, and are targeted for human immunotherapy. They are conventionally associated with the production of classical anti-inflammatory cytokines such as IL-10, TGF-β and IL-35, consistent to their anti-inflammatory functions. However, emerging evidence show that they also express effector cytokines such as IFN-γ and IL-17A under inflammatory conditions. While some studies reveal that these pro-inflammatory cytokine producing Foxp3(+) regulatory cells retain their suppressive ability, others believe that these cells are dys-regulated and are associated with perpetuation of immunopathology. Therefore the development of these cells may challenge the efficacy of human Treg therapy. Mechanistically, toll-like receptor (TLR) ligands and the pro-inflammatory cytokine milieu have been shown to play important roles in the induction of effector cytokines in Tregs. Here we review the mechanisms of development and the possible functions of pro-inflammatory cytokine producing Foxp3+ Tregs.

Quantification of biological network perturbations for mechanistic insight and diagnostics using two-layer causal models

BACKGROUND

High-throughput measurement technologies such as microarrays provide complex datasets reflecting mechanisms perturbed in an experiment, typically a treatment vs. control design. Analysis of these information rich data can be guided based on a priori knowledge, such as networks or set of related proteins or genes. Among those, cause-and-effect network models are becoming increasingly popular and more than eighty such models, describing processes involved in cell proliferation, cell fate, cell stress, and inflammation have already been published. A meaningful systems toxicology approach to study the response of a cell system, or organism, exposed to bio-active substances requires a quantitative measure of dose-response at network level, to go beyond the differential expression of single genes.

RESULTS

We developed a method that quantifies network response in an interpretable manner. It fully exploits the (signed graph) structure of cause-and-effect networks models to integrate and mine transcriptomics measurements. The presented approach also enables the extraction of network-based signatures for predicting a phenotype of interest. The obtained signatures are coherent with the underlying network perturbation and can lead to more robust predictions across independent studies. The value of the various components of our mathematically coherent approach is substantiated using several in vivo and in vitro transcriptomics datasets. As a proof-of-principle, our methodology was applied to unravel mechanisms related to the efficacy of a specific anti-inflammatory drug in patients suffering from ulcerative colitis. A plausible mechanistic explanation of the unequal efficacy of the drug is provided. Moreover, by utilizing the underlying mechanisms, an accurate and robust network-based diagnosis was built to predict the response to the treatment.

CONCLUSION

The presented framework efficiently integrates transcriptomics data and "cause and effect" network models to enable a mathematically coherent framework from quantitative impact assessment and data interpretation to patient stratification for diagnosis purposes.

Recognition strategies of group 3 innate lymphoid cells

During the early phase of an inflammatory response, innate cells can use different strategies to sense environmental danger. These include the direct interaction of specific activating receptors with pathogen-encoded/danger molecules or the engagement of cytokine receptors by pro-inflammatory mediators produced by antigen presenting cells in the course of the infection. These general recognition strategies, which have been extensively described for innate myeloid cells, are shared by innate lymphoid cells (ILC), such as Natural Killer (NK) cells. The family of ILC has recently expanded with the discovery of group 2 (ILC2) and group 3 ILC (ILC3), which play an important role in the defense against extracellular pathogens. Although ILC3 and NK cells share some phenotypic characteristics, the recognition strategies employed by the various ILC3 subsets have been only partially characterized. In this review, we will describe and comparatively discuss how ILC3 sense environmental cues and how the triggering of different receptors may regulate their functional behavior during an immune response.

The class III histone deacetylase sirtuin 1 in immune suppression and its therapeutic potential in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic debilitating disease of the joints. Both the innate and adaptive immune responses participate in the development and progression of RA. While several therapeutic reagents, such as TNF-α agonists, have been successfully developed for the clinical use in the treatment of RA, more than half of the patients do not respond to anti-TNF therapy. Therefore, new therapeutic reagents are needed. Recent studies have shown that sirtuin 1 (Sirt1), a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, is a critical negative regulator of both the innate and adaptive immune response in mice, and its altered functions are likely to be involved in autoimmune diseases. Small molecules that modulate Sirt1 functions are potential therapeutic reagents for autoimmune inflammatory diseases. This review highlights the role of Sirt1 in immune regulation and RA.

Modulation of the immune and inflammatory responses by Plasmodium falciparum schizont extracts: role of myeloid dendritic cells in effector and regulatory functions of CD4+ lymphocytes

The optimal immune response to malaria infection comprises rapid induction of inflammatory responses promptly counteracted by regulatory mechanisms to prevent immunopathology. To evaluate the role of dendritic cells (DC) in the balance of parasite-induced inflammatory/anti-inflammatory mechanisms, we studied the activity of monocyte-derived dendritic cells (MDDC), previously exposed to soluble extracts of Plasmodium falciparum-infected red blood cells (PfSE), in the differentiation of CD4 cells isolated from donors never exposed to malaria infection. We show that MDDC exposed to PfSE are extremely efficient to induce a contemporary differentiation of TH1 effector cells and T regulatory (Treg) cells in CD4 T cells even when exposed to low concentrations of parasitic extracts. Treg cells induced by MDDC infected with PfSE (MDDC-PfSE) produce transforming growth factor beta (TGF-β) and interleukin 10 (IL-10) and are endowed with strong suppressive properties. They also show phenotypical and functional peculiarities, such as the contemporary expression of markers of Treg and TH1 differentiation and higher sensitivity to TLR4 ligands both inducing an increasing production of suppressive cytokines. On the whole, our data indicate that MDDC exposed to PfSE orchestrate a well-balanced immune response with timely differentiation of TH1 and Treg cells in CD4 cells from nonimmune donors and suggest that, during the infection, the role of MDCC could be particularly relevant in low-parasitemia conditions.

Heat shock proteins and regulatory T cells

Heat shock proteins (HSPs) are important molecules required for ideal protein function. Extensive research on the functional properties of HSPs indicates that HSPs may be implicated in a wide range of physiological functions including immune function. In the immune system, HSPs are involved in cell proliferation, differentiation, cytokine release, and apoptosis. Therefore, the ability of the immune system, in particular immune cells, to function optimally and in unison with other physiological systems is in part dependent on signaling transduction processes, including bidirectional communication with HSPs. Regulatory T cells (Tregs) are important T cells with suppressive functions and impairments in their function have been associated with a number of autoimmune disorders. The purpose of this paper is to examine the relationship between HSPs and Tregs. The interrelationship between cells and proteins may be important in cellular functions necessary for cell survival and expansion during diseased state.

Human immunodeficiency virus type 1 Nef in human monocyte-like cell line THP-1 expands treg cells via toll-like receptor 2

CD4(+) CD25(+) regulatory T cells (Tregs) represent a unique T-cell lineage that is endowed with the ability to actively suppress immune responses in order to inhibit pathogenic damage resulting from over activation of the immune system. In human immunodeficiency virus-1 (HIV-1) infection, suppression of the immune response by Tregs appears to play an opposing role that promotes chronic viral infection. Treg expansion is known as a marker of the severity of HIV infection and as a potential prognostic marker of disease progression. HIV-1 Nef is one of the earliest expressed viral regulatory genes whose expression may play an important role in regulating Treg cells. We established a THP-1 cell line stably expressing HIV-1 Nef and showed that Nef protein was a potent factor for increasing Treg numbers in vitro. We further found that TLR2 plays a critical role in the increase in Treg cells induced by Nef using TLR2-specific siRNA. Our results suggest new strategies for therapeutic and preventive interventions of HIV infection.

A combination of exosomes carrying TSA derived from HLA-A2-positive human white buffy coat and polyI:C for use as a subcellular antitumor vaccination

To improve its antitumor effect, we used human leukocyte antigen -A2 (HLA-A2)-positive human dendritic cell (DC)-derived DEXs (DC-derived exosomes) to support NY-ESO-1 antigen and polyI:C, with the aim of increasing the proliferation of specific cytotoxic T lymphocytes (CTL) in transgenic mice. Mature dendritic cells derived from peripheral blood mononuclear cells (PBMC) were isolated from the blood of healthy adults with positive HLA-2A. Using centrifuge and membrane ultrafiltration, EXO (exosomes) were extracted from the supernatant of DCs secretions. Transgenic C57 mice were immunized with human-derived tumor testis antigen NY-ESO-1/EXO, with or without polyI:C. Mice were sacrificed four weeks after immunization, and spleen cells were isolated and tested for function. The experiments included antigen-specific CTL proliferation, as tested by dimerization and antitumor effects for K562 cells as well as melanoma, tested at different ratios of effected cells:target cells (0:1, 10:1, 50:1, and 100:1). Dimerization experiments indicated that the effect of DEX/TSA (tumor specific antigens) + PolyI:C was 2.36 ± 1.10% and the control was 0.38 ± 0.31%, while the effect of DEX/TSA was 1.97 ± 0.63% and the control was 0.36 ± 0.07%. Antitumor effects by DEX/TSA: PolyI:C for the cell ratios of 0:1, 10:1, 50:1, and 100:1 were 11.14 ± 1.36%, 14.17 ± 0.62%, 15.71 ± 2.48%, and 24.31 ± 2.91%, respectively, for K562 cells. The antitumor effects for DEX/TSA for the cell ratios of 0:1, 10:1, 50:1, and 100:1 were 12.23 ± 2.25%, 13.10 ± 1.57%, 15.27 ± 2.93%, and 19.87 ± 2.72%, respectively, for K562 cells. With ratios of 10:1 and 100:1, the antitumor effects of DEX/TSA + PolyI:C were better than for the DEX/TSA group (P < 0.05). However, higher ratios of effecter cells to target cells increased, and there were no significant improvements in antitumor effect for control cells. Combining PolyI:C with DEX/TSA derived from healthy human blood positive for HLA-A2 is a promising strategy for developing new subcellular antitumor vaccination.

Effect of tiotropium bromide on expression of CD(8) (+)CD (25) (+)FoxP (3) (+) regulatory T cells in patients with stable chronic obstructive pulmonary disease

The expression of CD(8) (+)CD(25) (+)FoxP(3) (+) regulatory T cells (CD(8) (+)Tregs) in the peripheral blood of patients with stable chronic obstructive pulmonary disease (COPD), and the effect of muscarinic cholinergic receptor antagonist tiotropium bromide on the expression of CD(8) (+)Tregs were investigated. Twenty-three patients with moderate to severe stable COPD were enrolled in this study. All patients inhaled tiotropium bromide (18 μg daily) for 3 months. Before and after inhalation of tiotropium bromide, peripheral blood samples were collected from the patients, and T cells were labeled by three-color labeled monoclonal antibodies. Flow cytometry was used to detect the quantity and percentage of CD(8) (+)T cells, CD(8) (+)CD(25) (+)T cells, CD(8) (+)Tregs, CD(4) (+)T cells, CD(4) (+)CD(25) (+)T cells and CD(4) (+)CD(25) (+)FoxP(3) (+) regulatory T cells (CD(4) (+)Tregs) respectively. The percentage of CD(4) (+)T cells was increased from (27.82±2.18)% to (35.53±1.3)% (t=3.20, P=0.004) in the peripheral blood of patients with stable COPD after inhalation of tiotropium bromide for 3 months, that of CD(4) (+)CD(25) (+)T cells was decreased from (10.03 ±1.42)% to (4.21 ±0.65)% (t=3.78, P=0.001), and that of CD(8) (+)Tregs was increased from (8.41 ±1.68)% to (21.34 ±4.20)% (t=2.72, P=0.013). At baseline, CD(8) (+)T cells, CD(8) (+)CD(25) (+)T cells and CD(4) (+)Tregs were detectable in the peripheral blood, but no significant changes were observed after treatment. Linear correlation analysis revealed that the difference before and after treatment in CD(4) (+)T cells and CD(4) (+)CD(25) (+)T cells was negatively correlated with the ratio of change in CD(8) (+)Tregs before and after treatment (r=-0.61, P=0.013; r=-0.72, P=0.001 respectively). In the peripheral blood of patients with stable COPD, there was the expression of CD(8) (+)Tregs and CD(4) (+)Tregs. Muscarinic receptor antagonist, tiotropium bromide, can promote the amplification of CD(4) (+)T cells, inhibit the expression of CD(25) (+)T cells, and enhance the expression of CD(8) (+)Tregs. CD(8) (+)Tregs and CD(4) (+)Tregs can be used as new indicators to understand the immune status of patients. They are helpful in judging the treatment efficacy and disease immunophenotype.

Polyubiquitin binding to ABIN1 is required to prevent autoimmunity

The polyubiquitin-binding domain of ABIN1 limits TLR-induced MyD88 signaling to prevent spontaneous autoimmunity in mice.

The protein ABIN1 possesses a polyubiquitin-binding domain homologous to that present in nuclear factor κB (NF-κB) essential modulator (NEMO), a component of the inhibitor of NF-κB (IκB) kinase (IKK) complex. To address the physiological significance of polyubiquitin binding, we generated knockin mice expressing the ABIN1[D485N] mutant instead of the wild-type (WT) protein. These mice developed all the hallmarks of autoimmunity, including spontaneous formation of germinal centers, isotype switching, and production of autoreactive antibodies. Autoimmunity was suppressed by crossing to MyD88^−/− mice, demonstrating that toll-like receptor (TLR)–MyD88 signaling pathways are needed for the phenotype to develop. The B cells and myeloid cells of the ABIN1[D485N] mice showed enhanced activation of the protein kinases TAK, IKK-α/β, c-Jun N-terminal kinases, and p38α mitogen-activated protein kinase and produced more IL-6 and IL-12 than WT. The mutant B cells also proliferated more rapidly in response to TLR ligands. Our results indicate that the interaction of ABIN1 with polyubiquitin is required to limit the activation of TLR–MyD88 pathways and prevent autoimmunity.

Engagement of TLR2 reverses the suppressor function of conjunctiva CD4+CD25+ regulatory T cells and promotes herpes simplex virus epitope-specific CD4+CD25- effector T cell responses

PURPOSE. The authors recently reported that Foxp3(+)CD4(+) CD25(+(Bright)) "natural" regulatory T cells (nT(reg) cells) are abundant in rabbit conjunctiva and suppress herpes simplex virus (HSV)-1-specific CD4(+) and CD8(+) effector T cells (T(eff) cells). However, little is known about the overall regulatory mechanisms of these nT(reg) cells. The authors investigate the regulation of conjunctiva-resident nT(reg) cells through Toll-like receptors (TLRs) and their effect on ocular mucosal T(eff) cell immunity. METHODS. CD4(+)CD25(+) nT(reg) cells were purified from naive rabbit conjunctivas, and their TLR expression profile was determined. The effects of TLR engagement on nT(reg) cell-mediated suppression of CD4(+) T(eff) cells were determined in vitro and in vivo. RESULTS. The authors found that conjunctiva-resident nT(reg) cells express high levels of TLR2 and TLR9; exposure to the TLR2 ligand lipoteichoic acid (LTA) led to the increased activation and proliferation of nT(reg) cells, and the addition of autologous APCs further increased nT(reg) cell expansion; in contrast, the TLR9 ligand CpG(2007) inhibited the proliferation of nT(reg) cells, and the addition of autologous APCs had no effect on such inhibition; nT(reg) cells treated with LTA, but not with CpG(2007), expressed IFN-γ and IL-10 mRNA, but not TGF-β; consistent with in vitro data, rabbits immunized by topical ocular drops of HSV-gD peptides + TLR2 ligand (LTA) displayed enhanced CD4(+)CD25(-) T(eff) cell immune responses when compared with HSV-gD peptides + TLR9 ligand (CpG(2007)). CONCLUSIONS. Although conjunctiva-resident CD4(+)CD25(+) nT(reg) cells express high level of TLR2 and TLR9, their suppressive function is more significantly reversed after the administration of TLR2 ligand (LTA; P < 0.005) than of TLR9 ligand (CpG(200); P > 0.005). These findings will likely help optimize the topical ocular administration of immunotherapies.

Toll-like receptor signaling in neural plasticity and disease

Toll-like receptors (TLRs) are a family of innate immune system receptors that respond to pathogen-derived and tissue damage-related ligands. TLR signaling in immune cells, glia and neurons can play roles in the pathogenesis of stroke, Alzheimer's disease (AD) and multiple sclerosis (MS). Recent findings suggest that TLR signaling also influences multiple dynamic processes in the developing and adult central nervous system including neurogenesis, axonal growth and structural plasticity. In addition, TLRs are implicated in the regulation of behaviors including learning, memory and anxiety. This review describes recently discovered and unexpected roles for TLRs in neuroplasticity, and the implications of these findings for future basic and translational research studies.

[Regulatory T cells and systemic autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis, primary Sjögren's syndrome]

Regulatory/suppressor T cells (Tregs) maintain immunologic homeostasis and prevent autoimmunity. They are the guardians of dominant tolerance. Recent research reveals quantitative and/or functional defect of Tregs in systemic autoimmune diseases. In this article, past and recent studies of Tregs in human systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and primary Sjögren's syndrome (pGSS) are reviewed. Most studies report that Tregs are decreased in peripheral blood of subjects with active SLE. A population of CD4+CD25-Foxp3+ is specifically described in SLE. Tregs functions are still discussed. Tregs counts in peripheral blood of RA patients vary across studies. Enrichment of synovial fluid in Tregs contrasts with inflammation. Tregs suppressive effects are altered in vivo in RA secondary to proinflammatory cytokines environment and resistance of effector T cells to Tregs. In pGSS, the conflicting place of Tregs in the balance prevention of autoimmunity/antitumor immunity is unspecified. Immunosuppressive treatments, like corticosteroids and anti-TNF, modulate Tregs cells population. There is increasing interest in the use of Tregs as a biological therapy to preserve and restore tolerance to self-antigen. However, difficulties to characterize these lymphocytes and controversies in the results of studies refrain their use in current clinical practice.

Correlation of circulating TLR2/4 expression with CD3+/4+/8+ T cells and Treg cells in HBV-related liver cirrhosis

Toll-like receptors (TLRs) 2 and 4 play a key role in chronic hepatitis B virus (HBV) infection. However, the role of TLRs in the pathogenesis of HBV-related liver cirrhosis and their regulation of the innate immune response of patients with liver cirrhosis remain unknown. To assess the contribution of TLR2/4 in HBV-related liver cirrhosis, we examined the expression of circulating TLR2 and TLR4 on peripheral blood mononuclear cells (PBMCs), CD4(+)CD25(+)CD127(low/-) Treg proportions, and CD3(+)/CD4(+)/CD8(+) T-cell counts in 30 liver cirrhosis patients, 21 chronic hepatitis B (CHB) patients, and 16 normal controls (NC). Furthermore, we analyzed the relationship between TLR2/4 expression and Treg proportions and T-cell counts. We show that the expression of TLR2 and TLR4 was significantly upregulated in patients with liver cirrhosis compared to NC. TLR4 expression was significantly increased in patients with liver cirrhosis compared to patients with CHB, and for TLR2 expression there were no differences between them. TLR4 expression showed a significant positive correlation with the frequency of Tregs in liver cirrhosis patients. TLR2 expression negatively correlated with CD3(+)/CD4(+)/CD8(+) T-cell counts and HBV viral load in patients with liver cirrhosis. These findings indicate that TLR may be involved in the pathogenesis of HBV-related liver cirrhosis, and may interact with Tregs and CD3(+)/CD4(+)/CD8(+) T cells in the immune response during HBV-related liver cirrhosis.

TLR2 activation is essential to induce a Th1 shift in human peripheral blood mononuclear cells by plant stanols and plant sterols

Plant sterols may induce a Th1 shift in humans. However, whether plant stanols have similar effects as well as the underlying mechanism are unknown. We have now shown that (like sitosterol) sitostanol, both 4-desmethylsterols, induces a Th1 shift when added in vitro at physiological concentrations to human PBMCs. This conclusion was based on a higher IFNgamma production, with no change in the production of IL-4 and IL-10. alpha-Amyrin, a 4.4-dimethylsterol, had comparable effects. Because 4.4-dimethylsterols cannot activate transcription factor LXR, this finding indicates that LXR activation was not involved. Sitosterol and sitostanol did not alter the production of IL-12 and IL-18 in PBMCs as well as in monocyte-derived U937 cells, suggesting that plant sterols directly affect T-helper cells, without activating APCs. However, in PBMCs treated with a TLR2 blocker (T2.5), IFNgamma production was completely inhibited, whereas blocking TLR4 with HTA125 had no such effect. To confirm these findings, PBMCs from TLR2(-/-) mice were cultured in the presence of sitosterol and sitostanol. In these cells, no Th1 shift was observed. Our results, therefore, indicate that TLR2 activation is essential to induce a Th1 shift in human PBMCs by plant stanols and plant sterols.

Anti-tumour effects of exosomes in combination with cyclophosphamide and polyinosinic-polycytidylic acid

We examined the anti-tumour activity of exosomes derived from dendritic cells (DCs) in combination with cyclophosphamide (CTX) and polyinosinic-polycytidylic acid sodium salt (poly I:C). DCs were pulsed with L1210 lymphocytic leukaemia cell antigen and lipopolysaccharide. The exosomes that the DCs secreted were purified. In vitro, the anti-tumour activity of exosomes was assessed by measuring their ability to induce spleen cell proliferation and the extent to which they induced spleen cells to kill L1210 cells. Poly I:C was able to induce DC maturation. DC-derived exosomes stimulated spleen cell proliferation and enhanced the cytotoxic effects of spleen cells in vitro. DC-derived exosomes, in combination with CTX and poly I:C, suppressed L1210 tumour growth in vivo and gave the greatest prolongation of survival time in tumour-bearing DBA2 mice. These findings suggest that this combination of a tumour vaccine, a conventional anti-cancer agent and a promoter of DC maturation might be a useful anti-cancer therapy.

A TLR2 polymorphism is associated with type 1 diabetes and allergic asthma

Type 1 diabetes (T1D) and allergic asthma are immune-mediated diseases. Pattern recognition receptors are proteins expressed by cells in the immune system to identify microbial pathogens and endogenous ligands. Toll-like receptors (TLRs) and CD14 are members of this family and could represent a molecular link between microbial infections and immune-mediated diseases. Diverging hypotheses regarding whether there exists a common or inverse genetic etiology behind these immune-mediated diseases have been presented. We aimed to test whether there exist common or inverse associations between polymorphisms in the pattern recognition receptors TLR2, TLR4 and CD14 and T1D and allergic asthma. Eighteen single nucleotide polymorphisms (SNPs) were genotyped in TLR2 (2), TLR4 (12) and CD14 (4) in 700 T1D children, 357 nuclear families with T1D children and 796 children from the 'Environment and Childhood Asthma' study. Allele and haplotype frequencies were analyzed in relation to diseases and in addition transmission disequilibrium test analyses were performed in the family material. Both T1D and allergic asthma were significantly associated with the TLR2 rs3804100 T allele and further associated with the haplotype including this SNP, possibly representing a susceptibility locus common for the two diseases. Neither TLR4 nor CD14 were associated with T1D or allergic asthma.

The role of T-regulatory cells and Toll-like receptors in the pathogenesis of human inflammatory bowel disease

Two related chronic inflammatory diseases, Crohn's disease and ulcerative colitis, are together often referred to as inflammatory bowel disease (IBD). Current treatment options are not curative, and patients face lifelong therapy and debilitation. IBD is thought to be the product of a combination of genetic and environmental factors that result in the abnormal regulation of immune responses. Experimental models have demonstrated that normal CD4+ T-regulatory (Treg) cell responses and commensal bacteria are required for the maintenance of gut immune homeostasis. Recent evidence that CD4+ T cells express Toll-like receptors (TLRs) and respond directly to TLR ligands, suggests that signals from commensal bacteria may directly affect T-cell responses in the gut. In this review, we focus on evidence that defects in Treg cells may underlie IBD in humans. In addition, we discuss evidence that direct signaling via TLRs to T cells can affect IBD and that T-cell-dependent responses to bacterial proteins, such as flagellin, are central to the aetiology of this disease.

The role of T-regulatory cells and Toll-like receptors in the pathogenesis of human inflammatory bowel disease

Two related chronic inflammatory diseases, Crohn's disease and ulcerative colitis, are together often referred to as inflammatory bowel disease (IBD). Current treatment options are not curative, and patients face lifelong therapy and debilitation. IBD is thought to be the product of a combination of genetic and environmental factors that result in the abnormal regulation of immune responses. Experimental models have demonstrated that normal CD4+ T-regulatory (Treg) cell responses and commensal bacteria are required for the maintenance of gut immune homeostasis. Recent evidence that CD4+ T cells express Toll-like receptors (TLRs) and respond directly to TLR ligands, suggests that signals from commensal bacteria may directly affect T-cell responses in the gut. In this review, we focus on evidence that defects in Treg cells may underlie IBD in humans. In addition, we discuss evidence that direct signaling via TLRs to T cells can affect IBD and that T-cell-dependent responses to bacterial proteins, such as flagellin, are central to the aetiology of this disease.

Toll-like receptors in neurodegeneration

The key roles of toll-like receptors (TLRs) as mediators of the detection and responses of immune cells to invading pathogens are well known. There are at least 13 mammalian TLRs which are integral membrane proteins with a leucine-rich extracellular domain and a cytoplasmic domain similar to that of the interleukin-1 receptor which initiates downstream signaling through kinases to activate transcription factors such as AP-1 and NFkappaB. TLRs are activated in glial cells (microglia, astrocytes and oligodendrocytes) and lymphocytes that infiltrate the nervous system in response to inflammation caused by infectious agents, tissue injury or autoimmune conditions. By inducing the production of pro-inflammatory cytokines and cell adhesion molecules in immune cells, TLRs may indirectly damage neurons in conditions such as ischemic stroke and multiple sclerosis. Recent findings suggest that neurons also express a subset of TLRs and that their activation promotes neuronal degeneration in experimental models of stroke and Alzheimer's disease. TLRs may also play roles in regulating the processes of neurogenesis and neurite outgrowth, suggesting roles in neuronal plasticity. A better understanding of the molecular and cellular biology of TLRs in the normal and diseased nervous system, may lead to novel approaches for preventing neuronal degeneration and promoting recovery of function in an array of neurodegenerative conditions.

Induction of TLR2 expression by inflammatory stimuli is required for endothelial cell responses to lipopeptides

Human endothelial cells (EC) express Toll-like receptor 4 (TLR4), a receptor for lipopolysaccharides (LPS), but little or no TLR2, a lipopeptide receptor. The aim of this study was to investigate to what extent inflammatory stimuli modify the expression by EC of TLR4 and TLR2, of the TLR2 co-receptors TLR1 and TLR6 and of the TLR2-accessory proteins CD14 and CD36. Stimulation of umbilical vein derived EC with TNF-alpha, LPS or IL-1beta for 24h induced a strong increase in TLR2 mRNA but not in TLR1, TLR4 and TLR6 mRNA. Inflammatory activation had little effect on CD14 mRNA, but decreased the expression of CD36 mRNA. TLR2 antigen was readily detected by flow cytometry on activated EC, but not on resting EC. A significant proportion of TLR2 was found to be located intracellularly. By using specific signalling pathway inhibitors we established that the induction of TLR2 by inflammatory stimuli was dependent on NF-kappaB, p38-MAP kinase and c-Jun kinase. IRAK-1 phosphorylation after treatment with 10mug/ml of lipoteichoic acid (LTA), a TLR2 agonist, was only observed in TNF-alpha-stimulated EC and not in resting EC. Furthermore, LTA potentiated the increase of the inflammatory markers E-Selectin or IL-8 in EC pre-treated with TNF-alpha, LPS or IL-1beta, but not in resting EC. These results imply that the up-regulated TLR2 is functionally active. Interestingly, LTA had no effect on TLR2 expression, nor maintained TLR2 expression, in activated EC. This suggests that lipopeptide responses of EC are dependent on the continued presence of inflammatory cytokines, provided by other cell types, or LPS. In conclusion, inflammatory stimuli induce a high TLR2 expression in EC, which in turn enables the cells to strongly respond to lipopeptides. The up-regulation of TLR2 may be of relevance for the vascular effects of Gram-positive bacteria.

TLR2/6 stimulation of the rat lung: effects on lymphocyte subsets, natural killer cells and dendritic cells in different parts of the air-conducting compartments and at different ages

The composition of lymphocyte subsets in the lung has been found to be compartment-specific. To characterize the effect of age, weanling, young adult and adult rats were studied in control conditions and after a single intratracheal dose of the Toll-like receptor 2/6 (TLR2/6) agonist macrophage activating lipopeptide-2 (MALP-2). In all age groups, T, B and natural killer (NK) cells increased dramatically in the epithelium and lamina propria of the bronchi. Male adult rats were found to have responded to MALP-2 to a much greater extent than females when lymphocyte subsets were counted in the epithelium and the lamina propria. In a second series of experiments the time kinetics of regulatory T-cell (Treg) subsets and dendritic cells (DCs) in the lung was studied after local stimulation with MALP-2. Different time-dependent patterns were found in the Treg subsets CD4(+) CD25(+), CD4(+) CD25(+) neuropilin 1(+) and CD4(+) CD25(+) Foxp3(+) cells. Neutrophils and DCs also showed different patterns. Thus, the local application of a TLR agonist increased the number of lymphocyte subsets in a compartment-specific pattern. However, data should not be generalized or extrapolated from one age group, sex or lymphocyte subpopulation to another.