A Toll-like receptor 3 (TLR3) agonist ARNAX for therapeutic immunotherapy

Dysfunction of dendritic cells in tumor microenvironment and immunotherapy

Dendritic cells (DCs) comprise diverse cell populations that play critical roles in antigen presentation and triggering immune responses in the body. However, several factors impair the immune function of DCs and may promote immune evasion in cancer. Understanding the mechanism of DC dysfunction and the diverse functions of heterogeneous DCs in the tumor microenvironment (TME) is critical for designing effective strategies for cancer immunotherapy. Clinical applications targeting DCs summarized in this report aim to improve immune infiltration and enhance the biological function of DCs to modulate the TME to prevent cancer cells from evading the immune system. Herein, factors in the TME that induce DC dysfunction, such as cytokines, hypoxic environment, tumor exosomes and metabolites, and co-inhibitory molecules, have been described. Furthermore, several key signaling pathways involved in DC dysfunction and signal-relevant drugs evaluated in clinical trials were identified. Finally, this review provides an overview of current clinical immunotherapies targeting DCs, especially therapies with proven clinical outcomes, and explores future developments in DC immunotherapies.

Revitalizing antitumor immunity: Leveraging nucleic acid sensors as therapeutic targets

Nucleic acid sensors play a critical role in recognizing and responding to pathogenic nucleic acids as danger signals. Upon activation, these sensors initiate downstream signaling cascades that lead to the production and release of pro-inflammatory cytokines, chemokines, and type I interferons. These immune mediators orchestrate diverse effector responses, including the activation of immune cells and the modulation of the tumor microenvironment. However, careful consideration must be given to balancing the activation of nucleic acid sensors to avoid unwanted autoimmune or inflammatory responses. In this review, we provide an overview of nucleic acid sensors and their role in combating cancer through the perception of various aberrant nucleic acids and activation of the immune system. We discuss the connections between different programmed cell death modes and nucleic acid sensors. Finally, we outline the development of nucleic acid sensor agonists, highlighting how their potential as therapeutic targets opens up new avenues for cancer immunotherapy.

Targeting innate immune pathways for cancer immunotherapy

The innate immune system is critical for inducing durable and protective T cell responses to infection and has been increasingly recognized as a target for cancer immunotherapy. In this review, we present a framework wherein distinct innate immune signaling pathways activate five key dendritic cell activities that are important for T cell-mediated immunity. We discuss molecular pathways that can agonize these activities and highlight that no single pathway can agonize all activities needed for durable immunity. The immunological distinctions between innate immunotherapy administration to the tumor microenvironment versus administration via vaccination are examined, with particular focus on the strategies that enhance dendritic cell migration, interferon expression, and interleukin-1 family cytokine production. In this context, we argue for the importance of appreciating necessity vs. sufficiency when considering the impact of innate immune signaling in inflammation and protective immunity and offer a conceptual guideline for the development of efficacious cancer immunotherapies.

Lenvatinib Induces Immunogenic Cell Death and Triggers Toll-Like Receptor-3/4 Ligands in Hepatocellular Carcinoma

Purpose

Immunogenic cell death (ICD) is a cell death modality that plays a vital role in anticancer therapy. In this study, we investigated whether lenvatinib induces ICD in hepatocellular carcinoma and how it affects cancer cell behavior.

Patients and Methods

Hepatoma cells were treated with 0.5 μM lenvatinib for two weeks, and damage-associated molecular patterns were assessed using the expression of calreticulin, high mobility group box 1, and ATP secretion. Transcriptome sequencing was performed to investigate the effects of lenvatinib on hepatocellular carcinoma. Additionally, CU CPT 4A and TAK-242 were used to inhibit TLR3 and TLR4 expressions, respectively. Flow cytometry was used to assess PD-L1 expression. Kaplan-Meier and Cox regression models were applied for prognosis assessment.

Results

After treatment with lenvatinib, there was a significant increase in ICD-associated damage-associated molecular patterns, such as calreticulin on the cell membrane, extracellular ATP, and high mobility group box 1, in hepatoma cells. Following treatment with lenvatinib, there was a significant increase in the downstream immunogenic cell death receptors, including TLR3 and TLR4. Furthermore, lenvatinib increased the expression of PD-L1, which was later inhibited by TLR4. Interestingly, inhibiting TLR3 in MHCC-97H and Huh7 cells strengthened their proliferative capacity. Moreover, TLR3 inhibition was identified as an independent risk factor for overall survival and recurrence-free survival in patients with hepatocellular carcinoma.

Conclusion

Our study revealed that lenvatinib induced ICD in hepatocellular carcinoma and upregulated PD-L1 expression through TLR4 while promoting cell apoptosis through TLR3. Antibodies against PD-1/PD-L1 can enhance the efficacy of lenvatinib in the management of hepatocellular carcinoma.

Toward Establishing an Ideal Adjuvant for Non-Inflammatory Immune Enhancement

The vertebrate immune system functions to eliminate invading foreign nucleic acids and foreign proteins from infectious diseases and malignant tumors. Because pathogens and cancer cells have unique amino acid sequences and motifs (e.g., microbe-associated molecular patterns, MAMPs) that are recognized as "non-self" to the host, immune enhancement is one strategy to eliminate invading cells. MAMPs contain nucleic acids specific or characteristic of the microbe and are potential candidates for immunostimulants or adjuvants. Adjuvants are included in many vaccines and are a way to boost immunity by deliberately administering them along with antigens. Although adjuvants are an important component of vaccines, it is difficult to evaluate their efficacy ex vivo and in vivo on their own (without antigens). In addition, inflammation induced by currently candidate adjuvants may cause adverse events, which is a hurdle to their approval as drugs. In addition, the lack of guidelines for evaluating the safety and efficacy of adjuvants in drug discovery research also makes regulatory approval difficult. Viral double-stranded (ds) RNA mimics have been reported as potent adjuvants, but the safety barrier remains unresolved. Here we present ARNAX, a noninflammatory nucleic acid adjuvant that selectively targets Toll-like receptor 3 (TLR3) in antigen-presenting dendritic cells (APCs) to safely induce antigen cross-presentation and subsequently induce an acquired immune response independent of inflammation. This review discusses the challenges faced in the clinical development of novel adjuvants.

Small molecules in the treatment of COVID-19

The outbreak of COVID-19 has become a global crisis, and brought severe disruptions to societies and economies. Until now, effective therapeutics against COVID-19 are in high demand. Along with our improved understanding of the structure, function, and pathogenic process of SARS-CoV-2, many small molecules with potential anti-COVID-19 effects have been developed. So far, several antiviral strategies were explored. Besides directly inhibition of viral proteins such as RdRp and Mpro, interference of host enzymes including ACE2 and proteases, and blocking relevant immunoregulatory pathways represented by JAK/STAT, BTK, NF-κB, and NLRP3 pathways, are regarded feasible in drug development. The development of small molecules to treat COVID-19 has been achieved by several strategies, including computer-aided lead compound design and screening, natural product discovery, drug repurposing, and combination therapy. Several small molecules representative by remdesivir and paxlovid have been proved or authorized emergency use in many countries. And many candidates have entered clinical-trial stage. Nevertheless, due to the epidemiological features and variability issues of SARS-CoV-2, it is necessary to continue exploring novel strategies against COVID-19. This review discusses the current findings in the development of small molecules for COVID-19 treatment. Moreover, their detailed mechanism of action, chemical structures, and preclinical and clinical efficacies are discussed.

Immune Checkpoint and Other Receptor-Ligand Pairs Modulating Macrophages in Cancer: Present and Prospects

Immunotherapy, especially immune checkpoint blocking, has become the primary anti-tumor treatment in recent years. However, the current immune checkpoint inhibitor (ICI) therapy is far from satisfactory. Macrophages are a key component of anti-tumor immunity as they are a common immune cell subset in tumor tissues and act as a link between innate and adaptive immunity. Hence, understanding the regulation of macrophage activation in tumor tissues by receptor-ligand interaction will provide promising macrophage-targeting strategies to complement current adaptive immunity-based immunotherapy and traditional anti-tumor treatment. This review aims to offer a systematic summary of the current advances in number, structure, expression, biological function, and interplay of immune checkpoint and other receptor-ligand between macrophages and tumor cells.

Host-pathogen protein-nucleic acid interactions: A comprehensive review

Recognition of pathogen-derived nucleic acids by host cells is an effective host strategy to detect pathogenic invasion and trigger immune responses. In the context of pathogen-specific pharmacology, there is a growing interest in mapping the interactions between pathogen-derived nucleic acids and host proteins. Insight into the principles of the structural and immunological mechanisms underlying such interactions and their roles in host defense is necessary to guide therapeutic intervention. Here, we discuss the newest advances in studies of molecular interactions involving pathogen nucleic acids and host factors, including their drug design, molecular structure and specific patterns. We observed that two groups of nucleic acid recognizing molecules, Toll-like receptors (TLRs) and the cytoplasmic retinoic acid-inducible gene (RIG)-I-like receptors (RLRs) form the backbone of host responses to pathogen nucleic acids, with additional support provided by absent in melanoma 2 (AIM2) and DNA-dependent activator of Interferons (IFNs)-regulatory factors (DAI) like cytosolic activity. We review the structural, immunological, and other biological aspects of these representative groups of molecules, especially in terms of their target specificity and affinity and challenges in leveraging host-pathogen protein-nucleic acid interactions (HP-PNI) in drug discovery.

Recent advances in cancer immunotherapy: Modulation of tumor microenvironment by Toll-like receptor ligands

Immunotherapy is considered a promising approach for cancer treatment. An important strategy for cancer immunotherapy is the use of cancer vaccines, which have been widely used for cancer treatment. Despite the great potential of cancer vaccines for cancer treatment, their therapeutic effects in clinical settings have been limited. The main reason behind the lack of significant therapeutic outcomes for cancer vaccines is believed to be the immunosuppressive tumor microenvironment (TME). The TME counteracts the therapeutic effects of immunotherapy and provides a favorable environment for tumor growth and progression. Therefore, overcoming the immunosuppressive TME can potentially augment the therapeutic effects of cancer immunotherapy in general and therapeutic cancer vaccines in particular. Among the strategies developed for overcoming immunosuppression in TME, the use of toll-like receptor (TLR) agonists has been suggested as a promising approach to reverse immunosuppression. In this paper, we will review the application of the four most widely studied TLR agonists including agonists of TLR3, 4, 7, and 9 in cancer immunotherapy.

TLR3 Expression is a Potential Prognosis Biomarker and Shapes the Immune-Active Tumor Microenvironment in Esophageal Squamous Cell Carcinoma

BACKGROUND

Toll-like receptor 3 (TLR3) not only plays a crucial role in innate immune and inflammation but also in anti-cancer immunity. Nevertheless, the clinicopathological outcome of TLR3 in ESCC is still ambiguous.

METHODS

Immunohistochemistry was performed to investigate TLR3 expression and its impact on survival in 137 ESCC patients (including paired esophageal tissues with different stages of early lesions from 37 patients). Furthermore, we downloaded ESCC RNA-seq datasets (including phenotype and survival data) from The Cancer Genome Atlas (TCGA). The relationship between TLR3 and prognosis, biological landscape, and immune infiltration was assessed to verify the immunohistochemical results of our tissue samples, explore the possible mechanism of prognostic outcomes, and predict the sensitivity of immunotherapy.

RESULTS

TLR3 protein expression displayed an increasing trend in the progression through different grades of cellular atypia, from normal, esophageal simple hyperplasia (ESSH), intraepithelial neoplasia (IEN) to ESCC (P < 0.0083). TLR3 protein had a positive association with inflammation level (Rho = 0.341, P < 0.001). TLR3 mRNA expression was significantly higher in comparison to adjacent normal tissues (P < 0.001). Cox regression analysis indicated high TLR3 protein and mRNA expression conferred good prognosis in our samples and TCGA, especially for advanced ESCC patients (TNM stage III and IV). Overexpression of TLR3 resulted in an immune-active microenvironment via the recruitment of immune-active cells including cytotoxic lymphocytes (CTLs), CD8+ T cells, NK cells, dendritic cells, and M1-type macrophages. TLR3 expression was correlated with the pro-inflammatory cytokines and chemokines relating to anti-tumor immunity. Moreover, GSEA analysis indicated upregulated expression of TLR3 could activate the apoptotic pathway.

CONCLUSION

High TLR3 expression in ESCC patients was associated with a more favorable prognosis, immune-active cell infiltration, and an activated apoptotic pathway. TLR3 has potential applications for immunotherapy and immune response prediction in patients with ESCC.

Macrophage-Based Combination Therapies as a New Strategy for Cancer Immunotherapy

BACKGROUND

Cells of the immune system can inhibit tumor growth and progression; however, immune cells can also promote tumor cell growth, survival, and angiogenesis as a result of the immunosuppressive microenvironments. In the last decade, a growing number of new therapeutic strategies focused on reversing the immunosuppressive status of tumor microenvironments (TMEs), to reprogram the TME to be normal, and to further activate the antitumor functions of immune cells. Most of the "hot tumors" are encompassed with M2 macrophages promoting tumor growth, and the accumulation of M2 macrophages into tumor islets leads to poor prognosis in a wide variety of tumors.

SUMMARY

Therefore, how to uncover more immunosuppressive signals and to reverse the M2 tumor-associated macrophages (TAMs) to M1-type macrophages is essential for reversing the immunosuppressive state. Except for reeducation of TAMs in the cancer immunotherapy, macrophages as central effectors and regulators of the innate immune system have the capacity of phagocytosis and immune modulation in macrophage-based cell therapies.

KEY MESSAGES

We review the current macrophage-based cell therapies that use genetic engineering to augment macrophage functionalities with antitumor activity for the application of novel genetically engineered immune cell therapeutics. A combination of TAM reeducation and macrophage-based cell strategy may bring us closer to achieving the original goals of curing cancer. In this review, we describe the characteristics, immune status, and tumor immunotherapy strategies of macrophages to provide clues and evidences for future macrophage-based immune cell therapies.

The Role of Toll-like Receptors (TLRs) Mediated Inflammation in Pancreatic Cancer Pathophysiology

Pancreatic cancer (PC) is one of the most lethal forms of cancer, characterized by its aggressiveness and metastatic potential. Despite significant improvements in PC treatment and management, the complexity of the molecular pathways underlying its development has severely limited the available therapeutic opportunities. Toll-like receptors (TLRs) play a pivotal role in inflammation and immune response, as they are involved in pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Activation of TLRs initiates a signaling cascade, which in turn, leads to the transcription of several genes involved in inflammation and anti-microbial defense. TLRs are also deregulated in several cancers and can be used as prognostic markers and potential targets for cancer-targeted therapy. In this review we discuss the current knowledge about the role of TLRs in PC progression, focusing on the available TLRs-targeting compounds and their possible use in PC therapy.

TLR3 agonists: RGC100, ARNAX, and poly-IC: a comparative review

Toll-like receptors 3 (TLR3) have been broadly studied among all TLRs over the last few decades together with its agonists due to their contribution to cancer regression. These agonists undeniably have some shared characteristics such as mimicking dsRNA but pathways through which they exhibit antitumor properties are relatively diverse. In this review, three widely studied agonists RGC100, ARNAX, and poly-IC are discussed along with their structural and physiochemical differences including the signaling cascades through which they exert their actions. Comparison has been made to identify the finest agonist with maximum effectivity and the least side effect profile.

Toll-Like Receptor-Based Strategies for Cancer Immunotherapy

Toll-like receptors (TLRs) are expressed and play multiple functional roles in a variety of immune cell types involved in tumor immunity. There are plenty of data on the pharmacological targeting of TLR signaling using agonist molecules that boost the antitumor immune response. A recent body of research has also demonstrated promising strategies for improving the cell-based immunotherapy methods by inducing TLR signaling. These strategies include systemic administration of TLR antagonist along with immune cell transfer and also genetic engineering of the immune cells using TLR signaling components to improve the function of genetically engineered immune cells such as chimeric antigen receptor-modified T cells. Here, we explore the current status of the cancer immunotherapy approaches based on manipulation of TLR signaling to provide a perspective of the underlying rationales and potential clinical applications. Altogether, reviewed publications suggest that TLRs make a potential target for the immunotherapy of cancer.

PLGA-particle vaccine carrying TLR3/RIG-I ligand Riboxxim synergizes with immune checkpoint blockade for effective anti-cancer immunotherapy

With emerging supremacy, cancer immunotherapy has evolved as a promising therapeutic modality compared to conventional antitumor therapies. Cancer immunotherapy composed of biodegradable poly(lactic-co-glycolic acid) (PLGA) particles containing antigens and toll-like receptor ligands induces vigorous antitumor immune responses in vivo. Here, we demonstrate the supreme adjuvant effect of the recently developed and pharmaceutically defined double-stranded (ds)RNA adjuvant Riboxxim especially when incorporated into PLGA particles. Encapsulation of Riboxxim together with antigens potently activates murine and human dendritic cells, and elevated tumor-specific CD8+ T cell responses are superior to those obtained using classical dsRNA analogues. This PLGA particle vaccine affords primary tumor growth retardation, prevention of metastases, and prolonged survival in preclinical tumor models. Its advantageous therapeutic potency was further enhanced by immune checkpoint blockade that resulted in reinvigoration of cytotoxic T lymphocyte responses and tumor ablation. Thus, combining immune checkpoint blockade with immunotherapy based on Riboxxim-bearing PLGA particles strongly increases its efficacy.

TLRs as a Promise Target Along With Immune Checkpoint Against Gastric Cancer

Gastric cancer (GC) is one of the most common cancers in the world, and the incidence of gastric cancer in Asia appears to increase in recent years. Although there is a lot of improvement in treatment approaches, the prognosis of GC is poor. So it is urgent to search for a novel and more effective treatment to improve the survival rate of patients. Both innate immunity and adaptive immunity are important in cancer. In the innate immune system, pattern recognition receptors (PRRs) activate immune responses by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs). Many studies have reported that TLRs are involved in the occurrence, development, and treatment of GC. Therefore, TLRs are potential targets for immunotherapy to gastric cancer. However, gastric cancer is a heterogeneous disorder, and TLRs function in GC is complex. TLRs agonists can be potentially used not only as therapeutic agents to treat gastric cancer but also as adjuvants in conjunction with other immunotherapies. They might provide a promising new target for GC treatment. In the review, we sort out the mechanism of TLRs involved in tumor immunity and summarize the current progress in TLRs-based therapeutic approaches and other immunotherapies in the treatment of GC.

Modulation of the Innate Immune Response by Targeting Toll-like Receptors: A Perspective on Their Agonists and Antagonists

Toll-like receptors (TLRs) are a class of proteins that recognize pathogen-associated molecular patterns (PAMPs) and damaged-associated molecular patterns (DAMPs), and they are involved in the regulation of innate immune system. These transmembrane receptors, localized at the cellular or endosomal membrane, trigger inflammatory processes through either myeloid differentiation primary response 88 (MyD88) or TIR-domain-containing adapter-inducing interferon-β (TRIF) signaling pathways. In the last decades, extensive research has been performed on TLR modulators and their therapeutic implication under several pathological conditions, spanning from infections to cancer, from metabolic disorders to neurodegeneration and autoimmune diseases. This Perspective will highlight the recent discoveries in this field, emphasizing the role of TLRs in different diseases and the therapeutic effect of their natural and synthetic modulators, and it will discuss insights for the future exploitation of TLR modulators in human health.

Double-Stranded Structure of the Polyinosinic-Polycytidylic Acid Molecule to Elicit TLR3 Signaling and Adjuvant Activity in Murine Intranasal A(H1N1)pdm09 Influenza Vaccination

Polyinosinic-polycytidylic acid (PIC) is a potent double-stranded RNA (dsRNA) adjuvant useful in intranasal influenza vaccination. In mice, the intensity and duration of immune responses to PIC correlated with the double-stranded chain length. A rational method to avoid PIC chain extension in PIC production is to use multiple short poly(I) molecules and one long poly(C) molecule for PIC assembly. In this study, we elucidate that a newly developed uPIC100-400 molecule comprising multiple 0.1 kb poly(I) molecules and one 0.4 kb poly(C) molecule effectively enhanced the immune responses in mice, by preventing the challenged viral propagation and inducing hemagglutinin-specific IgA, after intranasal A(H1N1)pdm09 influenza vaccination. Reduced intraperitoneal toxicity of PIC prepared with multiple short poly(I) molecules in mice indicates the widened effective range of uPIC100-400 as an adjuvant. In contrast to uPIC100-400, the PIC molecule comprising multiple 0.05 kb poly(I) molecules failed to elicit mouse mucosal immunity. These results were consistent with TLR3 response but not retinoic acid inducible gene I (RIG-I)-like receptor response in the cell assays, which suggests that the adjuvant effect of PIC in mouse intranasal immunization depends on TLR3 signaling. In conclusion, the double-stranded PIC with reduced toxicity developed in this study would contribute to the development of PIC-adjuvanted vaccines.

Targeting Toll-like receptor 3 in dendritic cells for cancer immunotherapy

INTRODUCTION

Activation of innate immune system is a key step to develop anti-tumor immunity. Antigen-presenting dendritic cells (DCs) cross-present tumor-associated antigens to cytotoxic CD8⁺ T cells (CTLs). Signaling from pattern-recognition receptors (PRRs) in DCs is required to induce tumor-specific CTLs.

AREAS COVERED

This review summarizes the properties of PRRs expressed by antigen-presenting DCs, especially TLR3, and provides the recent knowledge of their function in anti-tumor immunity. We also summarize the characteristics of newly-developed TLR3-specific agonist, ARNAX, which efficiently primes DCs to induce anti-tumor immunity without systemic inflammation in mice.

EXPERT OPINION

In cancer immunotherapy, the induction of tumor-specific CTLs is significant for tumor regression and to augment the efficacy of PD-1/PD-L1 blockade. Non-inflammatory TLR3 adjuvant ARNAX that can induce tumor-specific CTLs without inducing inflammation benefits cancer immunotherapy. Development of appropriate protocols for ARNAX vaccine therapy would be useful to overcome the PD-1/PD-L1 blockade resistance.

Developments in anticancer vaccination: budding new adjuvants

The immune system has a limited capacity to recognize and fight cells that become cancerous and in cancer patients, the immune system has to seek the right balance between cancer rejection and host-immunosupression. The tumor milieu builds a protective shell and tumor cells rapidly accumulate mutations that promote antigen variability and immune-escape. Therapeutic vaccination of cancer is a promising strategy the success of which depends on a powerful activation of the cells of the adaptive immune system specific for tumor-cell detection and killing (e.g. CD4+and CD8+T-cells). In the last decades, the search for novel adjuvants that enhance dendritic cell (DC) function and their ability to prime T-cells has flourished and some Toll-like receptor (TLR) agonists have long been known to be valid immune adjuvants. The implementation of TLR-synthetic agonists in clinical studies of cancer vaccination is replacing the initial use of microbial-derived products with some encouraging results. The purpose of this review is to summarize the latest discoveries of TLR-synthetic agonists with adjuvant potential in anti-cancer vaccination.

The Toll-Like Receptor 3 Agonist Polyriboinosinic Polyribocytidylic Acid Increases the Numbers of NK Cells with Distinct Phenotype in the Liver of B6 Mice

One of the activating factors of the cells of the innate immune system is the agonists of toll-like receptors (TLRs). Our earlier publications detailed how poly(I:C), a TLR3 agonist, elevates the NK cell population and the associated antigen-specific CD8⁺ T cell responses. This study involved a single treatment of the B6 mice with poly(I:C) intraperitoneally. To perform a detailed phenotypic analysis, mononuclear cells were prepared from each of the liver, peripheral blood, and spleen. These cells were then examined for their NK cell population by flow cytometric analysis following cell staining with indicated antibodies. The findings of the study showed that the NK cell population of the liver with an NK1.1^highCD11b^highCD11c^high B220⁺Ly6G^- phenotype was elevated following the treatment with poly(I:C). In the absence of CD11b molecule (CR3^-/- mice), poly(I:C) can still increase the remained numbers of NK cells with NK1.1⁺CD11b^- and NK1.1⁺Ly6G^- phenotypes in the liver while their numbers in the blood decrease. After the treatment with anti-AGM1 Ab, which induced depletion of NK1.1⁺CD11b⁺ cells and partial depletion of CD3⁺NK1.1⁺ and NK1.1⁺CD11b^- cell populations, poly(I:C) normalized the partial decreases in the numbers of NK cells concomitant with increased numbers of NK1.1^-CD11b⁺ cell population in both liver and blood. Regarding mice with a TLR3^-/- phenotype, their injection with poly(I:C) resulted in the partial elevation in the NK cell population as compared to wild-type B6 mice. To summarise, the TLR3 agonist poly(I:C) results in the elevation of a subset of liver NK cells expressing the two myeloid markers CD11c and CD11b. The effect of poly(I:C) on NK cells is partially dependent on TLR3 and independent of the presence of CD11b.

Toll-like receptor 3 -926T>A increased the risk of breast cancer through decreased transcriptional activity

Toll-like receptor 3 (TLR3) is a viral sensor that induces apoptosis in response to double-stranded RNA (dsRNA). Common genetic changes in the TLR3 gene may influence breast cancer susceptibility and development. However, all of the polymorphisms in the previous study were only markers of the TLR3 gene, not causative polymorphisms. In this study, we performed a case-control study focusing on the relationship between rs5743305 (-926T>A), a single nucleotide polymorphism (SNP) in the promoter region of TLR3, and breast cancer. We found that the genetic variant rs5743305 increased the risk of breast cancer under the dominant and codominant models (dominant model: AT+AA vs TT.: OR = 1.3023, 95%CI: 1.0778-1.5736, P = .0062; codominant model: AA vs. TT: OR = 1.3919, 95%CI: 1.0177-1.9036, P = .0384; AT vs. TT: OR = 1.2799, 95%CI: 1.0475-1.5639, P = .0158) but not under the recessive model (TT vs. AT+AA, OR = 1.2387, 95%CI: 0.9197-1.6682, P = .1588). The same trends were found in the age-adjusted logistic regression study and stage 2 study. Furthermore, the electrophoretic mobility shift assay (EMSA) and luciferase reporter assay showed that rs5743305 decreased the transcriptional activity of TLR3. There was consistently reduced TLR3 mRNA and protein expression in human breast cancer samples from patients with TLR3 - 926A. Therefore, TLR3 rs5743305 increases the risk of breast cancer by decreasing the transcriptional activity of TLR3. This study may provide a better understanding of the genetic architecture underlying disease susceptibility and may advance the potential for preclinical prediction in future genetic testing.