Toll-like receptor-2/7-mediated T cell activation: An innate potential to augment CD8+ T cell cytokine production

Activated platelets stimulate effector CD8+ T cells to enhance HNSCC immunotherapy efficacy

Programmed Death Receptor-1 (PD-1) is an immune checkpoint receptor expressed on the surface of T cells. Monoclonal antibodies targeting PD-1 and its ligand, PD-L1, are among the most widely utilized immune checkpoint inhibitors in cancer immunotherapy, dramatically improving the prognosis of patients with various malignancies. Traditionally, platelets, which are cytoplasmic fragments derived from megakaryocytes, have been primarily recognized for their roles in hemostasis and coagulation. However, recent studies have highlighted the emerging role of platelets in cancer biology and therapy. Platelets can modulate immune cell functions through various mechanisms, including the release of bioactive molecules and direct interactions with immune cells. A deeper understanding of the interplay between platelets and immune responses could pave the way for novel therapeutic strategies in cancer treatment. In our research, in patients with better treatment responses, there are higher levels of mature and activated CD8+ T cells in their PBMCs prior to treatment. Additionally, the activation of platelets is also more pronounced, and the proteins expressed on these platelets may modulate immune cells. After receiving immunotherapy, patients in the responsive (R) group exhibited a higher abundance of activated effector CD8+ T cells, which demonstrated stronger immune response capabilities. Furthermore, the increased levels of activated platelets in the R group may contribute to the regulation of CD8+ effector memory T cells, influencing their quantity and function. Our study suggests that the functional state of CD8+ T cells and the level of activated platelets prior to treatment may serve as predictive indicators for the efficacy of PD-1 inhibitors in head and neck cancer patients. Activated CD8+ effector T cells may contribute to the differences in immunotherapy responses, with activated platelets playing a role in promoting the maturation and activation of CD8+ effector memory T cells.These insights help better understand the interactions between platelets and immune cells, particularly emphasizing the role of CD8+ effector memory T cells in immunotherapy. Additionally, they offer potential strategies for predicting patient responses to PD-1 inhibitor treatment and optimizing the efficacy of immunotherapy.

Noncoding RNA (ncRNA)-mediated regulation of TLRs: critical regulator of inflammation in tumor microenvironment

Toll-like receptors (TLRs) are central components of the innate immune system as they recognize molecular patterns associated with pathogens and cellular damage and initiate immune responses using MyD88- and TRIF-dependent pathways. In contrast to being very useful for immune defense, dysregulated TLR signaling may be involved in diseases, such as cancer and autoimmune conditions. In cancer, TLRs create an environment that supports tumorigenesis and growth. In addition to this, a class of multifunctional noncoding RNAs (ncRNAs), including miRNAs, lncRNAs, and circRNAs, regulate gene expression without encoding proteins. MiRNAs regulate gene expression in a fine-tuned manner, while lncRNAs and circRNAs do so via diverse mechanisms. Notably, these ncRNAs interact, where lncRNAs and circRNAs function as competing endogenous RNAs and ceRNA, affecting miRNA activity. This interaction has a vital role in cancer pathology, in influencing that of various oncogenes and tumor suppressors in the tumor microenvironment; hence, modulation of ncRNAs could also be a great promising therapeutic approach. In this context, interplay between TLRs and ncRNAs is of paramount importance as they influence various parameters of the tumor microenvironment. TLR signaling works upon the expression of ncRNAs, while ncRNAs work back to regulate TLR signaling in return. An example of this includes miRNA targeting of components of the TLR; lncRNAs induced by TLR signaling possibly would favor tumor progression. Pharmacological interventions directed toward inhibiting these TLR pathways could be the model to halt malignancy by hampering pro-tumor inflammation and boosting immune responses against neoplasms. Hence, the review will highlight the complicated contrast of ncRNAs and TLRs within human cancer. By connecting the mechanisms, the researchers may study more about tumorigenesis and gather up new, innovative notions regarding therapeutic targeting.

The Novel Role of the Expression of Toll-like Receptors TLR-5, TLR-6, and TLR-9 and Associated Up-Regulation of Programmed Cell Death 1 Receptor (PD-1) and Its Ligand (PD-L1) in Lung Sepsis

Sepsis is a leading cause of death in hospitalized patients. The underlying pathophysiologic mechanisms of sepsis have not been fully elucidated thus far. The receptor of programmed cell death 1 (PD-1) and its ligand (PD-L1), in combination with the Toll-like receptors (TLRs), seem to contribute considerably in systematic responses during sepsis. Investigating the relationship between them and identifying potential target pathways is important in the future management of sepsis, especially in relation to acute lung injury. This study investigated the interactions between TLR-5, -6, and -9 and PD-1/PD-L1 expression in a septic mouse model. Sixty C57BL/6J mice were included and categorized in six study groups. Three sepsis (S) groups (24 h, 48 h, and 72 h) and three sham (Sh) groups (24 h, 48 h, and 72 h) were created. Cecal ligation and puncture (CLP) was utilized to simulate sepsis in the S groups. Hematological analysis and lung tissue histopathological analysis were performed after 24 h, 48 h, and 72 h. Significant decreases in S groups compared to Sh groups in WBC and lymphocyte counts at 24, 48, and 72 h were observed. Significant increases in S groups compared to Sh groups in RBC and monocyte counts, IL-6 and IL-10 levels, alveolar flooding, and alveolar collapse were demonstrated by histopathological analysis. This study suggested a strong correlation between TLR expression and PD-1/PD-L1 up-regulation in lung tissue during sepsis. These molecules, also, seem to contribute to the histopathological changes in lung tissue during sepsis, leading to acute lung injury.

Posttranscriptional Events Orchestrate Immune Homeostasis of CD8+ T Cells

Maintaining immune homeostasis is instrumental for host health. Immune cells, such as T cells, are instrumental for the eradication of pathogenic bacteria, fungi and viruses. Furthermore, T cells also play a major role in the fight against cancer. Through the formation of immunological memory, a pool of antigen-experienced T cells remains in the body to rapidly protect the host upon reinfection or retransformation. In order to perform their protective function, T cells produce cytolytic molecules, such as granzymes and perforin, and cytokines such as interferon γ and tumor necrosis factor α. Recently, it has become evident that posttranscriptional regulatory events dictate the kinetics and magnitude of cytokine production by murine and human CD8+ T cells. Here, the recent literature regarding the role posttranscriptional regulation plays in maintaining immune homeostasis of antigen-experienced CD8+ T cells is reviewed.

Revolutionizing medicine with toll-like receptors: A path to strengthening cellular immunity

Toll-like receptors play a vital role in cell-mediated immunity, which is crucial for the immune system's defense against pathogens and maintenance of homeostasis. The interaction between toll-like-receptor response and cell-mediated immunity is complex and essential for effectively eliminating pathogens and maintaining immune surveillance. In addition to pathogen recognition, toll-like receptors serve as adjuvants in vaccines, as molecular sensors, and recognize specific patterns associated with pathogens and danger signals. Incorporating toll-like receptor ligands into vaccines can enhance the immune response to antigens, making them potent adjuvants. Furthermore, they bridge the innate and adaptive immune systems and improve antigen-presenting cells' capacity to process and present antigens to T cells. The intricate signaling pathways and cross-talk between toll-like-receptor and T cell receptor (TCR) signaling emphasize their pivotal role in orchestrating effective immune responses against pathogens, thus facilitating the development of innovative vaccine strategies. This article provides an overview of the current understanding of toll-like receptor response and explores their potential clinical applications. By unraveling the complex mechanisms of toll-like-receptor signaling, we can gain novel insights into immune responses and potentially develop innovative therapeutic approaches. Ongoing investigations into the toll-like-receptor response hold promise in the future in enhancing our ability to combat infections, design effective vaccines, and improve clinical outcomes.

Nano-adjuvants and immune agonists promote antitumor immunity of peptide amphiphiles

Immunostimulatory cues play an important role in priming antitumor immunity and promoting the efficacy of subunit cancer vaccines. However, the clinical use of many immunostimulatory agents is often hampered by their inefficient in vivo delivery which may decrease immune response to the vaccination. To promote vaccine efficacy, we develop vaccine formulations which integrate three key elements: (1) a nano-adjuvant formulated by conjugating an agonistic anti-CD40 monoclonal antibody (αCD40) to the surface of a polyIC-loaded lipid nanoparticle, (2) a peptide amphiphile containing an optimized CD8⁺ T-cell epitope that derived from a melanoma antigen gp100, (3) an agonistic anti-4-1BB monoclonal antibody (α4-1BB) that boosts the efficacy of vaccinations. In a syngeneic mouse model of melanoma, the vaccine formulations enhanced innate immunity and activated multiple innate immune signaling pathways within draining lymph nodes, as well as promoted antigen-specific immune responses and reduced immunosuppression in the tumor microenvironment, leading to profound tumor growth inhibition and prolonged survival. Thus, our vaccine formulations represent an attractive strategy to stimulate antitumor immunity and control tumor progression. STATEMENT OF SIGNIFICANCE: The clinical use of many immunostimulatory agents is often hampered by their inefficient in vivo delivery which may decrease immune response to the vaccination. To promote the antitumor immunity of subunit vaccines, we develop novel vaccine formulations that integrate multifunctional modalities including (1) a nano-adjuvant containing anti-CD40 monoclonal antibody (αCD40) and TLR3 agonist which activate innate immunity through diverse signaling pathways, (2) a peptide amphiphile containing an optimized CD8⁺ T-cell epitope from tumor antigen, (3) an anti-4-1BB monoclonal antibody (α4-1BB) that boosts the efficacy of vaccinations. In this study, our vaccine formulations stimulate superior antitumor immunity and control tumor progression. The above nano-engineered platform and immunogenic biomacromolecules can be further applied to other T-cell-inducing vaccines.

AMP5A modulates Toll-like receptors 7 and 8 single-stranded RNA immune responses in PMA-differentiated THP-1 and PBMC

BACKGROUND

Dysregulation of antiviral immunity has been implicated in the progression of acute respiratory syndrome coronavirus 2 infection into severe cases of coronavirus disease of 2019 (COVID-19). Imbalances in the inflammatory response drive the overabundant production of pro-inflammatory cytokines and chemokines. The low molecular weight fraction of 5% human serum albumin commercial preparation (AMP5A) is a novel biologic drug currently under clinical investigation for the treatment of osteoarthritis and the hyperinflammatory response associated with COVID-19. This study aims to elucidate AMP5A effects following the activation of immune cells with agonists of Toll-like receptor (TLR) 7 and/or 8, which detect ssRNA viral sequences.

METHODS

CXCL10 ELISAs were used to evaluate the dynamics of myeloid cells activated with CL075 and CL307, agonists of TLR7/8 and TLR7, respectively. In addition, enrichment analysis of gene sets generated by ELISA arrays was utilized to gain insight into the biologic processes underlying the identified differentially expressed cytokine profiles. Finally, relative potency (REP) was employed to confirm the involvement of mechanisms of action paramount to AMP5A activity.

RESULTS

AMP5A inhibits the release of CXCL10 from both CL075- and CL307-activated PMA-differentiated THP-1 and peripheral blood mononuclear cells. Furthermore, AMP5A suppresses a distinct set of pro-inflammatory cytokines (including IL-1β, IL-6, IL-12, and CXCL10) associated with COVID-19 and pro-inflammatory NF-κB activation. REP experiments using antagonists specific for the immunomodulatory transcription factors, peroxisome proliferator-activated receptor γ, and aryl hydrocarbon receptor, also indicate that these pathways are involved in the ability of AMP5A to inhibit CXCL10 release.

CONCLUSION

Due to the biphasic course of COVID-19, therapeutic approaches that augment antiviral immunity may be more beneficial early in infection, whereas later interventions should focus on inflammation suppression. In this study, we show that AMP5A inhibits TLR 7/8 signaling in myeloid cells, resulting in a decrease in inflammatory mediators associated with hyperinflammation and autoimmunity. Furthermore, data demonstrating that AMP5A activates immunomodulatory transcription factors found to be protective in lung disease is provided. These findings suggest that the modes and mechanisms of action of AMP5A are well suited to treat conditions involving dysregulated TLR 7/8 activation.

Glucocorticoid-Induced Leucine Zipper-Mediated TLR2 Downregulation Accounts for Reduced Neutrophil Activity Following Acute DEX Treatment

Glucocorticoids are the most powerful anti-inflammatory and immunosuppressive pharmacological drugs available, despite their adverse effects. Glucocorticoid-induced leucine zipper (GILZ) is a glucocorticoid-induced gene that shares several anti-inflammatory properties with glucocorticoids. Although immunosuppressive effects of glucocorticoids on neutrophils remain poorly understood, we previously demonstrated that GILZ suppresses neutrophil activation under glucocorticoid treatment. Here, we sought to explore the regulation of Toll-like receptor 2 (TLR2) by the synthetic glucocorticoid dexamethasone (DEX) on neutrophils and the associated GILZ involvement. Peripheral blood neutrophils were isolated from wild type and GILZ-knock-out (KO) mice. TLR2 was found to be downregulated by the in vivo administration of glucocorticoids in wild type but not in GILZ-KO neutrophils, suggesting the involvement of GILZ in TLR2 downregulation. Accordingly, the TLR2-associated anti-fungal activity of neutrophils was reduced by DEX treatment in wild type but not GILZ-KO neutrophils. Furthermore, GILZ did not interact with NF-κB but was found to bind with STAT5, a pivotal factor in the regulation of TLR2 expression. A similar modulation of TLR2 expression, impaired phagocytosis, and killing activity was observed in circulating human neutrophils treated in vitro with DEX. These results demonstrate that glucocorticoids reduce the ability of neutrophils to respond to infections by downregulating TLR2 via GILZ, thereby reducing critical functions.

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.

Post-transcriptional control of T-cell cytokine production: Implications for cancer therapy

As part of the adaptive immune system, T cells are vital for the eradication of infected and malignantly transformed cells. To perform their protective function, T cells produce effector molecules that are either directly cytotoxic, such as granzymes, perforin, interferon-γ and tumour necrosis factor α, or attract and stimulate (immune) cells, such as interleukin-2. As these molecules can also induce immunopathology, tight control of their production is required. Indeed, inflammatory cytokine production is regulated on multiple levels. Firstly, locus accessibility and transcription factor availability and activity determine the amount of mRNA produced. Secondly, post-transcriptional mechanisms, influencing mRNA splicing/codon usage, stability, decay, localization and translation rate subsequently determine the amount of protein that is produced. In the immune suppressive environments of tumours, T cells gradually lose the capacity to produce effector molecules, resulting in tumour immune escape. Recently, the role of post-transcriptional regulation in fine-tuning T-cell effector function has become more appreciated. Furthermore, several groups have shown that exhausted or dysfunctional T cells from cancer patients or murine models possess mRNA for inflammatory mediators, but fail to produce effector molecules, hinting that post-transcriptional events also play a role in hampering tumour-infiltrating lymphocyte effector function. Here, the post-transcriptional regulatory events governing T-cell cytokine production are reviewed, with a specific focus on the importance of post-transcriptional regulation in anti-tumour responses. Furthermore, potential approaches to circumvent tumour-mediated dampening of T-cell effector function through the (dis)engagement of post-transcriptional events are explored, such as CRISPR/Cas9-mediated genome editing or chimeric antigen receptors.