Surface toll-like receptor 9 on immune cells and its immunomodulatory effect

Role of TLRs as signaling cascades to combat infectious diseases: a review

Investigating innate immunity and its signaling transduction is essential to understand inflammation and host defence mechanisms. Toll-like receptors (TLRs), an evolutionarily ancient group of pattern recognition receptors, are crucial for detecting microbial components and initiating immune responses. This review summarizes the mechanisms and outcomes of TLR-mediated signaling, focusing on motifs shared with other immunological pathways, which enhances our understanding of the innate immune system. TLRs recognize molecular patterns in microbial invaders, activate innate immunity and promote antigen-specific adaptive immunity, and each of them triggers unique downstream signaling patterns. Recent advances have highlighted the importance of supramolecular organizing centers (SMOCs) in TLR signaling, ensuring precise cellular responses and pathogen detection. Furthermore, this review illuminates how TLR pathways coordinate metabolism and gene regulation, contributing to adaptive immunity and providing novel insights for next-generation therapeutic strategies. Ongoing studies hold promise for novel treatments against infectious diseases, autoimmune conditions, and cancers.

Cell-free DNA: plays an essential role in early diagnosis and immunotherapy of pancreatic cancer

Pancreatic cancer is renowned for its aggressive nature and dismal prognosis, with the majority of patients diagnosed at an advanced stage. The prognosis for patients with pancreatic cancer can be improved by early diagnosis and effective treatment. Circulating cell-free DNA (cfDNA) has emerged as a promising biomarker for the early diagnosis and monitoring of pancreatic cancer. This research presents a review of circulating cell-free DNA essential role in the early diagnosis and immunotherapy of pancreatic cancer. The detection methods of cfDNA, its potential as a diagnostic biomarker, and the latest research progress in cfDNA-based immunotherapy are discussed. The findings suggest that cfDNA plays a vital role in the early detection and personalised treatment of pancreatic cancer, holding great promise for improving patient outcomes.

Multidimensional applications of prussian blue-based nanoparticles in cancer immunotherapy

Immunotherapy holds notable progress in the treatment of cancer. However, the clinical therapeutic effect remains a significant challenge due to immune-related side effects, poor immunogenicity, and immunosuppressive microenvironment. Nanoparticles have emerged as a revolutionary tool to surmount these obstacles and amplify the potency of immunotherapeutic agents. Prussian blue nanoparticles (PBNPs) exhibit multi-dimensional immune function in cancer immunotherapy, including acting as a nanocarrier to deliver immunotherapeutic agents, as a photothermal agent to improve the efficacy of immunotherapy through photothermal therapy, as a nanozyme to regulate tumor microenvironment, and as an iron donor to induce immune events related to ferroptosis and tumor-associated macrophages polarization. This review focuses on the advances and applications of PBNPs in cancer immunotherapy. First, the biomedical functions of PBNPs are introduced. Then, based on the immune function of PBNPs, we systematically reviewed the multidimensional application of PBNPs in cancer immunotherapy. Finally, the challenges and future developments of PBNPs-based cancer immunotherapy are highlighted.

A Narrative Review of Periodontal Vaccines: Hope or Hype?

Globally, periodontal diseases, mainly driven by polymicrobial biofilms, are a widespread concern of social medicine due to their considerable incidence and tie-up to systemic disorders like diabetes, cardiovascular diseases, and complications during pregnancy. Traditional treatments focus on mechanical debridement and antimicrobial therapies, but these approaches have limitations, including recurrence and antibiotic resistance. Periodontal vaccines offer a promising alternative by targeting the immunological mechanisms underlying periodontal disease. This review explores the current state of periodontal vaccine development, highlighting key antigens, vaccine delivery systems, and preclinical and clinical advancements. Special emphasis is placed on antigen selection, host variability, immune tolerance, and future directions to overcome these barriers. This article highlights the advancements and challenges in periodontal vaccine research, offering insights into the capability of immunoprophylaxis as a groundbreaking way to manage periodontal diseases.

Toll-like receptor upregulation in liver and peripheral blood mononuclear cells of patients with amoebic liver abscess

AIM

We aimed to understand the host and microbe interactions at the time of infection and inflammatory response in amoebic liver abscess (ALA) patients based on toll-like receptor (TLR) expression (mRNA), cytokine and IgG subtypes levels.

METHODS AND RESULTS

Liver aspirates from 100 ALA patients and 11 liver autopsy samples were used as negative controls. Blood samples from 100 ALA and 41 healthy individuals were collected. mRNA expression of TLR 1 to 9 genes was measured using reverse transcriptase polymerase chain reaction (RT-PCR). Serum cytokines level was quantified by flow cytometry. In-house ELISA for the analysis of IgG and its subtypes in the serum samples was performed. A total of 7 TLR genes (TLR1, TLR2, TLR4, TLR6, TLR7, TLR8 and TLR9) and 6 TLR genes (TLR1, TLR2, TLR3, TLR4, TLR5 and TLR8) were found to be elevated in liver aspirates and PBMCs respectively. Increased serum cytokine levels were observed in ALA patients vs. healthy controls. Interestingly, a significant increase in IgG and its subtypes (IgG1, IgG3 and IgG4) was found in the serum of ALA patients.

CONCLUSION

Increased levels of TLR, pro- and anti-inflammatory cytokines, IgG and its subtypes, are possibly linked with early-stage infection in ALA patients.

IMPACT STATEMENT

The role of TLRs in association with ALA might provide insights into new therapeutic strategies.

DNA sensors in metabolic and cardiovascular diseases: Molecular mechanisms and therapeutic prospects

DNA sensors generally initiate innate immune responses through the production of type I interferons. While extensively studied for host defense against invading pathogens, emerging evidence highlights the involvement of DNA sensors in metabolic and cardiovascular diseases. Elevated levels of modified, damaged, or ectopically localized self-DNA and non-self-DNA have been observed in patients and animal models with obesity, diabetes, fatty liver disease, and cardiovascular disease. The accumulation of cytosolic DNA aberrantly activates DNA signaling pathways, driving the pathological progression of these disorders. This review highlights the roles of specific DNA sensors, such as cyclic AMP-GMP synthase and stimulator of interferon genes (cGAS-STING), absent in melanoma 2 (AIM2), toll-like receptor 9 (TLR9), interferon gamma-inducible protein 16 (IFI16), DNA-dependent protein kinase (DNA-PK), and DEAD-box helicase 41 (DDX41) in various metabolic disorders. We explore how DNA signaling pathways in both immune and non-immune cells contribute to the development of these diseases. Furthermore, we discuss the intricate interplay between metabolic stress and immune responses, offering insights into potential therapeutic targets for managing metabolic and cardiovascular disorders. Understanding the mechanisms of DNA sensor signaling in these contexts provides a foundation for developing novel interventions aimed at mitigating the impact of these pervasive health issues.

Delivery of dendritic cells targeting 3M2e-HA2 nanoparticles with a CpG adjuvant via lysosomal escape of Salmonella enhances protection against H9N2 avian influenza virus

Avian influenza virus (AIV) subtype H9N2 still poses a great threat to the poultry farming industry and public health worldwide, and the development of a new influenza vaccine that is safe and conservative and able to address influenza virus mutations is highly promising for application. HA2, the neck of the HA protein, and M2e, the extracellular N-terminal structural domain of the M2 protein, are conserved and effective protective antigens. In this study, the HA2 sequences were fused with three M2e copies (H9N2, H1N1 and H5N1) to the norovirus VP1 protein via the SpyTag-SpyCatcher platform to form self-assembled nanoparticles and display antigenic proteins on its surface, yielding pYL262. The chicken dendritic cells (DCs) targeting the nanobody phage-54 were then fused to HA2-3M2e to yield pYL327. Finally, a synthesized 20-repeat CpG adjuvant gene fragment was inserted into pYL327, resulting in the plasmid pYL331. All the constructed plasmids were then transformed into the sifA gene-deficient Salmonella vector χYL56 for oral immunization. The results showed that sifA-deficient Salmonella could efficiently increase antigen-specific mucosal sIgA antibody titers, especially in alveolar lavage samples, whereas the presence of the phage-54 nanobody could dramatically increase intracellular IFN-γ mRNA levels, indicating its ability to enhance the Th1-type immune response. Finally, the presence of the CpG adjuvant clearly increased T-cell proliferation and promoted DC activation, with elevated splenic TLR21 levels observed. Strikingly, after oral immunization with χYL56 (pYL331), chickens were protected against challenge with the G57 genotype H9N2 virus, which presented similar or even better levels of virus shedding and body weight gain compared with the commercial inactivated vaccine, providing a new option for controlling H9N2 virus infection in the future.

Nanomaterial-assisted delivery of CpG oligodeoxynucleotides for boosting cancer immunotherapy

Cancer immunotherapy aims to improve immunity to not only eliminate the primary tumor but also inhibit metastasis and recurrence. It is considered an extremely promising therapeutic approach that breaks free from the traditional paradigm of oncological treatment. As the medical community learns more about the immune system's mechanisms that "turn off the brake" and "step on the throttle", there is increasingly successful research on immunomodulators. However, there are still more restrictions than countermeasures with immunotherapy related to immunomodulators, such as low responsiveness and immune-related adverse events that cause multiple adverse reactions. Therefore, medical experts and materials scientists attempted to the efficacy of immunomodulatory treatments through various methods, especially nanomaterial-assisted strategies. CpG oligodeoxynucleotides (CpG) not only act as an adjuvant to promote immune responses, but also induce autophagy. In this review, the enhancement of immunotherapy using nanomaterial-based CpG formulations is systematically elaborated, with a focus on the delivery, protection, synergistic promotion of CpG efficacy by nanomaterials, and selection of the timing of treatment. In addition, we also discuss and prospect the existing problems and future directions of research on nanomaterials in auxiliary CpG therapy.

Elevated toll-like receptor 9 is associated with disease severity and kidney involvement in systemic lupus erythematosus

OBJECTIVES

Systemic lupus erythematosus (SLE) is associated with the activation of both innate and adaptive immune system. Infection is a significant environmental factor that is responsible for the development of SLE. Toll-like receptors (TLRs) are responsible for recognizing pathogens, and the expression of TLRs has been found to differ in SLE patients. Additionally, various infections have been reported to influence TLR expression. This study aimed to explore the relationship between TLRs and the onset, severity, and symptoms of SLE in the eastern Indian population.

METHODS

The study included 70 SLE patients and a control group matched for age and sex. RT-PCR was used to evaluate mRNA expression of TLRs 2, 4, 7, and 9. Statistical analyses were performed using GraphPad Prism software v.10.2.3.

RESULTS

Patients with SLE expressed significantly higher levels of TLR2 (p < 0.0001) and TLR9 (p = 0.012) than healthy controls. In lupus nephritis, TLR9 expression was higher than in SLE patients without kidney involvement (p = 0.037). Furthermore, a significant relationship was found between TLR9 expression and systemic lupus erythematosus disease activity index (SLEDAI) scores (p < 0.0001, Spearman's r = 0.47), implying the potential role of TLRs in SLE development. However, mRNA expression of TLR4 and TLR7 was not associated with SLE, clinical indices, or disease severity.

CONCLUSIONS

TLR9 is associated with SLE pathogenesis and clinical severity, making it a promising molecule for targeted therapy in SLE management.

Therapeutic Effects of PEG-Modified Polyamide Amine Dendrimer for Cell Free DNA Adsorption in Temporomandibular Joint Osteoarthritis

Temporomandibular joint osteoarthritis (TMJ OA) is characterized by the degeneration of cartilage and subchondral bone. In this study, we observed a significant increase in cell-free DNA (cfDNA) levels during the progression of TMJ OA. Bioinformatics analysis identified TLR9 as a pivotal molecule in TMJ OA pathogenesis. The polyamidoamine (PAMAM) dendrimer characterized by a well-structured, highly branched, and reactive nature, exhibits robust binding and clearance capabilities for cfDNA. However, the abundant amino groups on the surface of PAMAM lead to its inherent toxicity. To mitigate this, PEG-5000 was conjugated to the surface of PAMAM dendrimers, enhancing safety. Our results indicate that PEG-PAMAM effectively inhibits the upregulation of the TLR9 protein in TMJ OA, significantly suppressing the activation of the p-IκBα/p-NF-κB signaling pathway and subsequently decreasing chondrocyte inflammation and apoptosis, as evidenced by both in vivo and in vitro experiments. We conclude that PEG-PAMAM is a safe and effective material for in vivo applications, offering a promising therapeutic strategy for TMJ OA by targeting cfDNA clearance.

Understanding the Role of Toll-Like Receptors 9 in Breast Cancer

Breast cancer is a significant global issue, ranking as the second most common cancer among women worldwide and a leading cause of cancer-related deaths. Although the exact causes of this increase remain unclear, factors such as genetics, epigenetics, obesity, sedentary lifestyle, tobacco use, and vitamin D deficiency have been implicated. The Toll-like receptor 9 (TLR9) is recognized for its role in inflammation and innate immunity; however, its specific involvement in breast cancer pathogenesis requires further investigation. This study aims to systematically review the existing literature on TLR9 expression in normal and cancerous breast tissue, providing current knowledge and identifying gaps. Relevant articles in English were from PubMed, Scopus, and Google Scholar, with the inclusion criteria focusing on studies evaluating TLR9 mRNA and protein expression. The review found that TLR9 mRNA and protein exhibit variable expressions in both normal and cancerous breast tissue, highlighting the need for further research to clarify TLR9's role in breast cancer.

Tumor- and Fibroblast-Derived Cell-Free DNAs Differently Affect the Progression of B16 Melanoma In Vitro and In Vivo

It is widely postulated that the majority of pathologically elevated extracellular or cell-free DNA (cfDNA) in cancer originates from tumor cells; however, evidence has emerged regarding the significant contributions of other cells from the tumor microenvironment. Here, the effect of cfDNA originating from murine B16 melanoma cells and L929 fibroblasts on B16 cells was investigated. It was found that cfDNAL929 increased the viability and migration properties of B16 cells in vitro and their invasiveness in vivo. In contrast, cfDNAB16 exhibited a negative effect on B16 cells, reducing their viability and migration in vitro, which in vivo led to decreased tumor size and metastasis number. It was shown that cell treatment with both cfDNAs resulted in an increase in the expression of genes encoding DNases and the oncogenes Braf, Kras, and Myc. cfDNAL929-treated cells were shown to experience oxidative stress. Gene expression changes in the case of cfDNAB16 treatment are well correlated with the observed decrease in proliferation and migration of B16 cells. The obtained data may indicate the possible involvement of fibroblast DNA in the tumor microenvironment in tumor progression and, potentially, in the formation of new tumor foci due to the transformation of normal cells.

Asian flush is a potential protective factor against COVID-19: a web-based retrospective survey in Japan

BACKGROUND

Coronavirus disease 2019 (COVID-19), first reported in December 2019, spread worldwide in a short period, resulting in numerous cases and associated deaths; however, the toll was relatively low in East Asia. A genetic polymorphism unique to East Asians, Aldehyde dehydrogenase 2 rs671, has been reported to confer protection against infections.

METHOD

We retrospectively investigated the association between the surrogate marker of the rs671 variant, the skin flushing phenomenon after alcohol consumption, and the timing of COVID-19 incidence using a web-based survey tool to test any protective effects of rs671 against COVID-19.

RESULTS

A total of 807 valid responses were received from 362 non-flushers and 445 flushers. During the 42 months, from 12/1/2019 to 5/31/2023, 40.6% of non-flushers and 35.7% of flushers experienced COVID-19. Flushers tended to have a later onset (Spearman's partial rank correlation test, p = 0.057, adjusted for sex and age). Similarly, 2.5% of non-flushers and 0.5% of flushers were hospitalized because of COVID-19. Survival analysis estimated lower risks of COVID-19 and associated hospitalization among flushers (p = 0.03 and <0.01, respectively; generalized Wilcoxon test). With the Cox proportional hazards model covering 21 months till 8/31/2021, when approximately half of the Japanese population had received two doses of COVID-19 vaccine, the hazard ratio (95% confidence interval) of COVID-19 incidence was estimated to be 0.21 (0.10-0.46) for flusher versus non-flusher, with adjustment for sex, age, steroid use, and area of residence.

CONCLUSIONS

Our study suggests an association between the flushing phenomenon after drinking and a decreased risk of COVID-19 morbidity and hospitalization, suggesting that the rs671 variant is a protective factor. This study provides valuable information for infection control and helps understand the unique constitutional diversity of East Asians.

At the Crossroads of the cGAS-cGAMP-STING Pathway and the DNA Damage Response: Implications for Cancer Progression and Treatment

The evolutionary conserved DNA-sensing cGAS-STING innate immunity pathway represents one of the most important cytosolic DNA-sensing systems that is activated in response to viral invasion and/or damage to the integrity of the nuclear envelope. The key outcome of this pathway is the production of interferon, which subsequently stimulates the transcription of hundreds of genes. In oncology, the situation is complex because this pathway may serve either anti- or pro-oncogenic roles, depending on context. The prevailing understanding is that when the innate immune response is activated by sensing cytosolic DNA, such as DNA released from ruptured micronuclei, it results in the production of interferon, which attracts cytotoxic cells to destroy tumors. However, in tumor cells that have adjusted to significant chromosomal instability, particularly in relapsed, treatment-resistant cancers, the cGAS-STING pathway often supports cancer progression, fostering the epithelial-to-mesenchymal transition (EMT). Here, we review this intricate pathway in terms of its association with cancer progression, giving special attention to pancreatic ductal adenocarcinoma and gliomas. As the development of new cGAS-STING-modulating small molecules and immunotherapies such as oncolytic viruses involves serious challenges, we highlight several recent fundamental discoveries, such as the proton-channeling function of STING. These discoveries may serve as guiding lights for potential pharmacological advancements.