TLR-mediated metabolic reprogramming in the tumor microenvironment: potential novel strategies for cancer immunotherapy

Divergent functions of TLRs in gastrointestinal (GI) cancer: Overview of their diagnostic, prognostic and therapeutic value

The relationship between the innate immune signal and the start of the adaptive immune response is the central idea of this theory. By controlling the inflammatory and tissue-repair reactions to damage, the Toll-like receptors (TLRs), as a family of PRRs, have attracted increasing attention for its function in protecting the host against infection and preserving tissue homeostasis. Microbial infection, damage, inflammation, and tissue healing have all been linked to the development of malignancies, especially gastrointestinal (GI) cancers. Recently, increased studies on TLR recognition and binding, as well as their ligands, have significantly advanced our knowledge of the various TLR signaling pathways and offered therapy options for GI malignancies. Upon activation by pathogen-associated or damage-associated molecular patterns (DAMPs and PAMPs), TLRs trigger key pathways like NF-κB, MAPK, and IRF. NF-κB activation promotes inflammation, cell survival, and proliferation, often contributing to tumor growth, metastasis, and therapy resistance. MAPK pathways similarly drive uncontrolled cell growth and invasion, while IRF pathways modulate interferon production, yielding both anti-tumor and protumor effects. The resulting chronic inflammatory environment within tumors can foster progression, yet TLR activation can also stimulate beneficial anti-tumor immune responses. However, the functions of TLR expression in GI cancers and their diagnostic and prognostic along with therapeutic value have not yet entirely been elucidated. Understanding how TLR activation contributes to anti-cancer immunity against GI malignancies may hasten immunotherapy developments and increase patient survival.

Toll-like Receptor Activation Remodels the Polyamine and Tryptophan Metabolism in Porcine Macrophages

Background: The early nutritional metabolism of piglets is intimately associated with the regulation of immune function, and amino acids play a crucial role in modulating the fate and function of porcine immune cells, especially macrophages. However, the metabolic changes upon macrophage activation remain elusive. Methods: We established an in vitro activation model of porcine macrophages and investigated alterations in metabolites involved in polyamine and tryptophan metabolism upon activation by various toll-like receptor (TLR) activators. Results: TLR activation inhibits the production of spermine and alters the kynurenine pathway of the tryptophan metabolism toward the kynurenic acid biosynthesis. Specifically, TLR9 activation redirects the metabolic pathway of tryptophan toward kynurenic acid synthesis, which subsequently inhibits melatonin production via the protein kinase A (PKA)/cyclic adenosine monophosphate (cAMP)/cAMP-responsive element-binding protein (CREB) signaling pathways. Conclusions: TLR activation reprograms the polyamine and tryptophan metabolism in porcine macrophages. Knowledge of the metabolic alterations in polyamine and tryptophan upon TLR activation in macrophages offers valuable insights and potential strategies for nutritional intervention to enhance piglet immunity.

Implication of Toll-Like Receptors in growth and management of health and diseases: Special focus as a promising druggable target to Prostate Cancer

Toll-like receptors (TLRs) are protein structures belonging to the pattern recognition receptors family. TLRs have the great potential that can directly recognize the specific molecular structures on the surface of pathogens, damaged senescent cells and apoptotic host cells. Available evidence suggests that TLRs have crucial roles in maintaining tissue homeostasis through control of the inflammatory and tissue repair responses during injury. TLRs are the player of first line of defense against different microbes and activate the signaling cascades which help to induce the immune system and inflammatory responses by affecting various signaling pathways, including nuclear factor-κB (NF-κB), interferon regulatory factors, and mitogen-activated protein kinases (MAPKs). TLRs have been identified to be over-expressed in different types of cancers and play an important role in control of health and management of diseases. The current review provides updated knowledge on the implication of TLRs in growth and management of cancers including prostate cancer.

Current status and future prospects of combined immunotherapy and epidermal growth factor receptor inhibitors in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a malignancy with a poor prognosis, and the majority of patients with HNSCC are diagnosed at later stages owing to its hidden anatomical location and atypical clinical symptoms. It is notably prone to recurrence and metastasis. The traditional treatments include surgery, radiotherapy, chemotherapy, and targeted therapy. Although multiple treatment strategies have been established, the prognosis remains poor because most patients develop resistance to traditional treatments. In recent years, epidermal growth factor receptor (EGFR) inhibitors and immune checkpoint inhibitors (ICIs) have been shown to provide clinical benefits to these patients. Based on the promising results of both anti-EGFR therapy and immunotherapy, as well as the biological rationale for combining immunotherapy with anti-EGFR drugs, numerous preclinical and ongoing or completed clinical trials have explored the use of their synergistic effects. This review summarizes the feasibility of combining immunotherapy with EGFR inhibitors for HNSCC treatment and analyses the relevant biomarkers. It also summarizes the strategies for clinical applications. We found that immunotherapy and EGFR inhibitor combination therapy showed promise in treating patients with HNSCC and exhibited safety with acceptable adverse events. This review may provide valuable insights for the future development of treatments and formulation of therapeutic strategies for HNSCC, as well as useful information for the future design of clinical trials.

The crosstalk between senescence, tumor, and immunity: molecular mechanism and therapeutic opportunities

Cellular senescence is characterized by a stable cell cycle arrest and a hypersecretory, proinflammatory phenotype in response to various stress stimuli. Traditionally, this state has been viewed as a tumor-suppressing mechanism that prevents the proliferation of damaged cells while activating the immune response for their clearance. However, senescence is increasingly recognized as a contributing factor to tumor progression. This dual role necessitates a careful evaluation of the beneficial and detrimental aspects of senescence within the tumor microenvironment (TME). Specifically, senescent cells display a unique senescence-associated secretory phenotype that releases a diverse array of soluble factors affecting the TME. Furthermore, the impact of senescence on tumor-immune interaction is complex and often underappreciated. Senescent immune cells create an immunosuppressive TME favoring tumor progression. In contrast, senescent tumor cells could promote a transition from immune evasion to clearance. Given these intricate dynamics, therapies targeting senescence hold promise for advancing antitumor strategies. This review aims to summarize the dual effects of senescence on tumor progression, explore its influence on tumor-immune interactions, and discuss potential therapeutic strategies, alongside challenges and future directions. Understanding how senescence regulates antitumor immunity, along with new therapeutic interventions, is essential for managing tumor cell senescence and remodeling the immune microenvironment.

Immunotherapy in gastrointestinal cancers: current strategies and future directions - a literature review

Introduction

The National Cancer Institute defines the disease of "cancer" as a group of disorders in which aberrant cells proliferate uncontrollably and have the potential to infiltrate neighboring tissues. It is well established that cancer remains a significant etiology contributing to worldwide mortality. Gastrointestinal (GI) neoplasms are a type of cancer that affects the digestive system and adds to the total cancer burden. Conventionally, several therapies have been employed, such as radiation and chemotherapy; nevertheless, their adverse effects have prompted the need for an improved therapeutic alternative. Immunotherapy thus became a notable medium of treatment for several malignancies, including tumors of the GI tract.

Aim

This comprehensive review seeks to provide insight on future directions and prospective therapies under development, as well as information regarding the present strategies utilized to mitigate one of the primary forms of cancer, GI cancer.

Methods

A detailed analysis of the existing literature on GI cancers has been conducted. Several databases were employed to gather this information, mainly PubMed/MEDLINE. Different aspects of the disease were considered when searching the databases to provide a comprehensive review of the current and future strategies being incorporated to mitigate the negative consequences of this disease.

Results

Many strategies are being used currently, and some are still under development. These comprise the usage of immune checkpoint inhibitors (ICIs), cytokine therapy, cancer vaccines, oncolytic viruses, and adoptive cell therapy. For instance, various monoclonal antibodies have been developed to inhibit the immunomodulatory effects of programmed death-1 and programmed death-1 ligand. There are also results of several clinical trials showing significant benefits and many changes are introduced to make the best of these strategies and minimize the challenges to group sizes. These challenges include overcoming the tumor's immunosuppressive environment, finding suitable predictive biomarkers, and reducing the adverse effects. Additionally, several novel immunotherapeutic approaches, such as chimeric antigen receptor T-cell (CAR-T) therapy, are being studied. In 2017, the US FDA approved the use of two CAR-T therapies, which marks a major milestone following extensive research and clinical trials. New approaches such as toll-like receptor-directed and helminth-based immunotherapies are being developed for the treatment of GI cancers as well. These therapies, along with targeted treatments, represent the future of immunotherapy in GI cancers.

Conclusion

Immunotherapy plays a significant role in the different types of GI cancers. However, optimizing these treatments will require overcoming barriers such as immune resistance, minimizing side effects, and improving the selection of patients through biomarkers. Continued research into these novel therapies and the mechanisms of immune modulation will be key to maximizing the therapeutic benefits of immunotherapy in the future.

Sex differences in disease: sex chromosome and immunity

Sex is a fundamental biological variable that influences immune system function, with sex chromosomes (X and Y) playing a central role in these differences. Despite substantial evidence of disparities in immune responses between males and females, biomedical research has historically overlooked sex as a critical factor. This oversight has contributed to the observed disparities in susceptibility to autoimmune diseases, infectious diseases, and malignancies between the sexes. In this review, we address the phenomena and mechanisms through which aberrant expression of sex chromosome-linked genes contributes to sex-based differences in immune responses. We specifically focus on the implications of X chromosome inactivation (XCI) escape and loss of Y chromosome (LOY). Our review aims to elucidate the molecular mechanisms driving these sex-based differences, with particular emphasis on the interactions between sex chromosome genes and immune cells in both males and females. Additionally, we discuss the potential impact of these differences on disease susceptibility and identify prospective therapeutic targets. As personalized and precision medicine advances, it is crucial to integrate sex differences into immunological research and clinical trials. We advocate for an increased focus on sex-based considerations in fundamental, translational, and clinical research to promote personalized, sex-specific healthcare.

Characteristics and mechanisms of T-cell senescence: A potential target for cancer immunotherapy

Immunosenescence, the aging of the immune system, leads to functional deficiencies, particularly in T cells, which undergo significant changes. While numerous studies have investigated age-related T-cell phenotypes in healthy aging, senescent T cells have also been observed in younger populations during pathological conditions like cancer. This review summarizes the recent advancements in age-associated alterations and markers of T cells, mechanisms, and the relationship between senescent T cells and the tumor microenvironment. We also discuss potential strategies for targeting senescent T cells to prevent age-related diseases and enhance tumor immunotherapy efficacy.

Targeting inflammation with hyaluronic acid-based micro- and nanotechnology: A disease-oriented review

Inflammation is a pivotal immune response in numerous diseases and presents therapeutic challenges. Traditional anti-inflammatory drugs and emerging cytokine inhibitors encounter obstacles such as limited bioavailability, poor tissue distribution, and adverse effects. Hyaluronic acid (HA), a versatile biopolymer, is widely employed to deliver therapeutic agents, including anti-inflammatory drugs, genes, and cell therapies owing to its unique properties, such as hydrophilicity, biodegradability, and safety. HA interacts with cell receptors to initiate processes such as angiogenesis, cell proliferation, and immune regulation. HA-based drug delivery systems offer dual strategies for effective inflammation management, capitalizing on passive and active mechanisms. This synergy permits the mitigation of inflammation by lowering the doses of anti-inflammatory drugs and their off-target adverse effects. A diverse array of micro- and nanotechnology techniques enable the fabrication of tailored HA-engineered systems, including hydrogels, microgels, nanogels, microneedles, nanofibers, and 3D-printed scaffolds, for diverse formulations and administration routes. This review explores recent insights into HA pharmacology in inflammatory conditions, material design, and fabrication methods, as well as its applications across a spectrum of inflammatory diseases, such as atherosclerosis, psoriasis, dermatitis, wound healing, rheumatoid arthritis, osteoarthritis, inflammatory bowel disease, and colitis, highlighting its potential for clinical translation.

Investigating the Immune-Stimulating Potential of β-Glucan from Aureobasidium pullulans in Cancer Immunotherapy

β-glucan, a polysaccharide found in various sources, exhibits unique physicochemical properties, yet its high polymerization limits clinical applications because of its solubility. Addressing this limitation, we introduce PPTEE-glycan, a highly purified soluble β-1,3/1,6-glucan derived from Aureobasidium pullulans. The refined PPTEE-glycan demonstrated robust immune stimulation in vitro, activated dendritic cells, and enhanced co-stimulatory markers, cytokines, and cross-presentation. Formulated as a PPTEE + microemulsion (ME), it elevated immune responses in vivo, promoting antigen-specific antibodies and CD8+ T cell proliferation. Intratumoral administration of PPTEE + ME in tumor-bearing mice induced notable tumor regression, which was linked to the activation of immunosuppressive cells. This study highlights the potential of high-purity Aureobasidium pullulans-derived β-glucan, particularly PPTEE, as promising immune adjuvants, offering novel avenues for advancing cancer immunotherapy.

Tumor microenvironment induced switch to mitochondrial metabolism promotes suppressive functions in immune cells

Understanding the intricacies of the metabolic phenotype in immune cells and its plasticity within the tumor microenvironment is pivotal in understanding the pathology and prognosis of cancer. Unfavorable conditions and cellular stress in the tumor microenvironment (TME) exert a profound impact on cellular functions in immune cells, thereby influencing both tumor progression and immune responses. Elevated AMP:ATP ratio, a consequence of limited glucose levels, activate AMP-activated protein kinase (AMPK) while concurrently repressing the activity of mechanistic target of rapamycin (mTOR) and hypoxia-inducible factor 1-alpha (HIF-1α). The intricate balance between AMPK, mTOR, and HIF-1α activities defines the metabolic phenotype of immune cells in the TME. These Changes in metabolic phenotype are strongly associated with immune cell functions and play a crucial role in creating a milieu conducive to tumor progression. Insufficiency of nutrient and oxygen supply leads to a metabolic shift in immune cells characterized by a decrease in glycolysis and an increase in oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) rates. In most cases, this shift in metabolism is accompanied by a compromise in the effector functions of these immune cells. This metabolic adaptation prompts immune cells to turn down their effector functions, entering a quiescent or immunosuppressive state that may support tumor growth. This article discusses how tumor microenvironment alters the metabolism in immune cells leading to their tolerance and tumor progression, with emphasis on mitochondrial metabolism (OXPHOS and FAO).

E3 Ubiquitin Ligase RNF13 Suppresses TLR Lysosomal Degradation by Promoting LAMP-1 Proteasomal Degradation

As a highly organized system, endo-lysosomes play a crucial role in maintaining immune homeostasis. However, the mechanisms involved in regulating endo-lysosome progression and subsequent inflammatory responses are not fully understood. By screening 103 E3 ubiquitin ligases in regulating endo-lysosomal acidification, it is discovered that lysosomal RNF13 inhibits lysosome maturation and promotes inflammatory responses mediated by endosomal Toll-like receptors (TLRs) in macrophages. Mechanistically, RNF13 mediates K48-linked polyubiquitination of LAMP-1 at residue K128 for proteasomal degradation. Upon TLRs activation, LAMP-1 promotes lysosomes maturation, which accelerates lysosomal degradation of TLRs and reduces TLR signaling in macrophages. Furthermore, peripheral blood mononuclear cells (PBMCs) from patients with rheumatoid arthritis (RA) show increased RNF13 levels and decreased LAMP-1 expression. Accordingly, the immunosuppressive agent hydroxychloroquine (HCQ) can increase the polyubiquitination of RNF13. Taken together, the study establishes a linkage between proteasomal and lysosomal degradation mechanisms for the induction of appropriate innate immune response, and offers a promising approach for the treatment of inflammatory diseases by targeting intracellular TLRs.

Sex as a Biological Variable in Early-Phase Oncology Clinical Trials: Enhancing the Path to Personalised Medicine

Sex is an essential biological variable that influences the development, progression and response to treatment in cancer. Despite this, early-phase cancer clinical trials frequently neglect to consider sex as a variable, creating a barrier to the development of personalised medicine. This article argues that failure to identify and infer sex differences in early-phase clinical trials may result in suboptimal dosing, underestimation of toxicity, and the failure to identify potential sex-specific responses to new systemic anticancer therapies. There should be a greater focus on sex as a biological variable in drug development so that thoughtful and deliberate study design can bring precision to the development of new systemic cancer therapies.

Immunoexpression pattern of TLR3 and TLR7 in minor salivary gland adenoid cystic carcinoma and its role in prognosis

OBJECTIVES

Adenoid cystic carcinoma (ACC) of the salivary glands has poor long-term prognosis and a high metastatic rate. Toll-like receptors (TLRs), first-line immune activators, have been associated with both tumor progression and suppression. We aimed to study TLR3 and TLR7 behavior in ACC.

MATERIALS AND METHODS

We studied TLR3 and TLR7 immunoexpression of 46 minor salivary gland ACCs diagnosed at the Department of Otorhinolaryngology - Head and Neck Surgery, Helsinki University Hospital, Helsinki, Finland over the period 1974-2012. The associations of TLR3 and TLR7 immunoexpression with clinicopathological factors were evaluated by χ2-test and Fisher's exact test.

RESULTS

In the majority of samples, both TLR3 and TLR7 were immunoexpressed in cytoplasm. The immunoexpression was heterogeneous between individual tumors. Stronger TLR7 immunoexpression associated with recurrence rate and poorer disease-specific survival (DSS). TLR3 did not associate significantly with survival although we found an inverse correlation between TLR3 and TLR7 immunopositivity. Hence, when TLR3 immunoexpression was negative or mild, TLR7 immunoexpression was moderate to strong, and vice versa.

CONCLUSIONS

TLR3 and TLR7 are immunoexpressed in minor salivary gland ACC. TLR7 is potentially an independent prognostic marker for recurrence rate and DSS.

Molecule engineering strategy of toll-like receptor 7/8 agonists designed for potentiating immune stimuli activation

Toll-like receptor 7/8 (TLR-7/8) agonists serve as a promising class of pattern recognition receptors that effectively evoke the innate immune response, making them promising immunomodulatory agents for tumor immunotherapy. However, the uncontrollable administration of TLR-7/8 agonists frequently leads to the occurrence of severe immune-related adverse events (irAEs). Thus, it is imperative to strategically design tumor-microenvironment-associated biomarkers or exogenous stimuli responsive TLR-7/8 agonists in order to accurately evaluate and activate innate immune responses. No comprehensive elucidation has been documented thus far regarding TLR-7/8 immune agonists that are specifically engineered to enhance immune activation. In this feature article, we provide an overview of the advancements in TLR-7/8 agonists, aiming to enhance the comprehension of their mechanisms and promote the clinical progression through nanomedicine strategies. The current challenges and future directions of cancer immunotherapy are also discussed, with the hope that this work will inspire researchers to explore innovative applications for triggering immune responses through TLR-7/8 agonists.

Regulatory mechanisms of PD-1/PD-L1 in cancers

Immune evasion contributes to cancer growth and progression. Cancer cells have the ability to activate different immune checkpoint pathways that harbor immunosuppressive functions. The programmed death protein 1 (PD-1) and programmed cell death ligands (PD-Ls) are considered to be the major immune checkpoint molecules. The interaction of PD-1 and PD-L1 negatively regulates adaptive immune response mainly by inhibiting the activity of effector T cells while enhancing the function of immunosuppressive regulatory T cells (Tregs), largely contributing to the maintenance of immune homeostasis that prevents dysregulated immunity and harmful immune responses. However, cancer cells exploit the PD-1/PD-L1 axis to cause immune escape in cancer development and progression. Blockade of PD-1/PD-L1 by neutralizing antibodies restores T cells activity and enhances anti-tumor immunity, achieving remarkable success in cancer therapy. Therefore, the regulatory mechanisms of PD-1/PD-L1 in cancers have attracted an increasing attention. This article aims to provide a comprehensive review of the roles of the PD-1/PD-L1 signaling in human autoimmune diseases and cancers. We summarize all aspects of regulatory mechanisms underlying the expression and activity of PD-1 and PD-L1 in cancers, including genetic, epigenetic, post-transcriptional and post-translational regulatory mechanisms. In addition, we further summarize the progress in clinical research on the antitumor effects of targeting PD-1/PD-L1 antibodies alone and in combination with other therapeutic approaches, providing new strategies for finding new tumor markers and developing combined therapeutic approaches.

Engineered CpG-Loaded Nanorobots Drive Autophagy-Mediated Immunity for TLR9-Positive Cancer Therapy

Smart nanorobots have emerged as novel drug delivery platforms in nanomedicine, potentially improving anti-cancer efficacy and reducing side effects. In this study, an intelligent tumor microenvironment-responsive nanorobot is developed that effectively delivers CpG payloads to Toll-like receptor 9 (TLR9)-positive tumors to induce autophagy-mediated cell death for immunotherapy. The nanorobots are fabricated by co-self-assembly of two amphiphilic triblock polymer peptides: one containing the matrix metallopeptidase 2 (MMP2)-cleaved GPLGVRGS motif to control the mechanical opening of the nanorobots and provide targeting capability for TLR-9-positive tumors and the other consisting of an arginine-rich GRRRDRGRS sequence that can condense nuclear acid payloads through electrostatic interactions. Using multiple tumor-bearing mouse models, it is investigated whether the intravenous injection of CpG-loaded nanorobots could effectively deliver CpG payloads to TLR-9-positive tumors and elicit anti-tumor immunity through TLR9 signaling and autophagy. Therefore, besides being a commonly used adjuvant for tumor vaccination, CpG-loaded nanorobots can effectively reprogram the tumor immunosuppressive microenvironment and suppress tumor growth and recurrence. This nanorobot-based CpG immunotherapy can be considered a feasible approach to induce anti-tumor immunity, showing great therapeutic potential for the future treatment of TLR9-positive cancers.

Identification of a novel m6A-related lncRNAs signature and immunotherapeutic drug sensitivity in pancreatic adenocarcinoma

BACKGROUND

Pancreatic adenocarcinoma (PDAC) ranks as the fourth leading cause for cancer-related deaths worldwide. N6-methyladenosine (m6A) and long non-coding RNAs (lncRNAs) are closely related with poor prognosis and immunotherapeutic effect in PDAC. The aim of this study is to construct and validate a m6A-related lncRNAs signature and assess immunotherapeutic drug sensitivity in PDAC.

METHODS

RNA-seq data for 178 cases of PDAC patients and 167 cases of normal pancreatic tissue were obtained from TCGA and GTEx databases, respectively. A set of 21 m6A-related genes were downloaded based on the previous report. Co-expression network was conducted to identify m6A-related lncRNAs in PDAC. Cox analyses and least absolute shrinkage and selection operator (Lasso) regression model were used to construct a risk prognosis model. The relationship between signature genes and immune function was explored by single-sample GSEA (ssGSEA). The tumor immune dysfunction and exclusion (TIDE) score and tumor mutation burden (TMB) were utilized to evaluate the response to immunotherapy. Furthermore, the expression levels of 4 m6A-related lncRNAs on PDAC cell lines were measured by the quantitative real-time PCR (qPCR). The drug sensitivity between the high- and low-risk groups was validated using PDAC cell lines by Cell-Counting Kit 8 (CCK8).

RESULTS

The risk prognosis model was successfully constructed based on 4 m6A-related lncRNAs, and PDAC patients were divided into the high- and low-risk groups. The overall survival (OS) of the high-risk groups was more unfavorable compared with the low-risk groups. Receiver operating characteristic (ROC) curves demonstrated that the risk prognosis model reasonably predicted the 2-, 3- and 5-year OS of PDAC patients. qPCR analysis confirmed the decreased expression levels of 4 m6A-related lncRNAs in PDAC cells compared to the normal pancreatic cells. Furthermore, CCK8 assay revealed that Phenformin exhibited higher sensitivity in the high-risk groups, while Pyrimethamine exhibited higher sensitivity in the low-risk groups.

CONCLUSION

The prognosis of patients with PDAC were well predicted in the risk prognosis model based on m6A-related lncRNAs, and selected immunotherapy drugs have potential values for the treatment of pancreatic cancer.

Targeting TREM1 augments antitumor T cell immunity by inhibiting myeloid-derived suppressor cells and restraining anti-PD-1 resistance

The triggering receptor expressed on myeloid cell 1 (TREM1) plays a critical role in development of chronic inflammatory disorders and the inflamed tumor microenvironment (TME) associated with most solid tumors. We examined whether loss of TREM1 signaling can abrogate the immunosuppressive TME and enhance cancer immunity. To investigate the therapeutic potential of TREM1 in cancer, we used mice deficient in Trem1 and developed a novel small molecule TREM1 inhibitor, VJDT. We demonstrated that genetic or pharmacological TREM1 silencing significantly delayed tumor growth in murine melanoma (B16F10) and fibrosarcoma (MCA205) models. Single-cell RNA-Seq combined with functional assays during TREM1 deficiency revealed decreased immunosuppressive capacity of myeloid-derived suppressor cells (MDSCs) accompanied by expansion in cytotoxic CD8+ T cells and increased PD-1 expression. Furthermore, TREM1 inhibition enhanced the antitumorigenic effect of anti-PD-1 treatment, in part, by limiting MDSC frequency and abrogating T cell exhaustion. In patient-derived melanoma xenograft tumors, treatment with VJDT downregulated key oncogenic signaling pathways involved in cell proliferation, migration, and survival. Our work highlights the role of TREM1 in cancer progression, both intrinsically expressed in cancer cells and extrinsically in the TME. Thus, targeting TREM1 to modify an immunosuppressive TME and improve efficacy of immune checkpoint therapy represents what we believe to be a promising therapeutic approach to cancer.

Toll-like receptor-guided therapeutic intervention of human cancers: molecular and immunological perspectives

Toll-like receptors (TLRs) serve as the body's first line of defense, recognizing both pathogen-expressed molecules and host-derived molecules released from damaged or dying cells. The wide distribution of different cell types, ranging from epithelial to immune cells, highlights the crucial roles of TLRs in linking innate and adaptive immunity. Upon stimulation, TLRs binding mediates the expression of several adapter proteins and downstream kinases, that lead to the induction of several other signaling molecules such as key pro-inflammatory mediators. Indeed, extraordinary progress in immunobiological research has suggested that TLRs could represent promising targets for the therapeutic intervention of inflammation-associated diseases, autoimmune diseases, microbial infections as well as human cancers. So far, for the prevention and possible treatment of inflammatory diseases, various TLR antagonists/inhibitors have shown to be efficacious at several stages from pre-clinical evaluation to clinical trials. Therefore, the fascinating role of TLRs in modulating the human immune responses at innate as well as adaptive levels directed the scientists to opt for these immune sensor proteins as suitable targets for developing chemotherapeutics and immunotherapeutics against cancer. Hitherto, several TLR-targeting small molecules (e.g., Pam3CSK4, Poly (I:C), Poly (A:U)), chemical compounds, phytocompounds (e.g., Curcumin), peptides, and antibodies have been found to confer protection against several types of cancers. However, administration of inappropriate doses of such TLR-modulating therapeutics or a wrong infusion administration is reported to induce detrimental outcomes. This review summarizes the current findings on the molecular and structural biology of TLRs and gives an overview of the potency and promises of TLR-directed therapeutic strategies against cancers by discussing the findings from established and pipeline discoveries.

Molecular characteristics and therapeutic implications of Toll-like receptor signaling pathway in melanoma

Melanoma is a malignant tumor of melanocytes and is often considered immunogenic cancer. Toll-like receptor-related genes are expressed differently in most types of cancer, depending on the immune microenvironment inside cancer, and the key function of Toll-like receptors (TLRs) for melanoma has not been fully elucidated. Based on multi-omics data from TCGA and GEO databases, we first performed pan-cancer analysis on TLR, including CNV, SNV, and mRNA changes in TLR-related genes in multiple human cancers, as well as patient prognosis characterization. Then, we divided melanoma patients into three subgroups (clusters 1, 2, and 3) according to the expression of the TLR pathway, and explored the correlation between TLR pathway and melanoma prognosis, immune infiltration, metabolic reprogramming, and oncogene expression characteristics. Finally, through univariate Cox regression analysis and LASSO algorithm, we selected six TLR-related genes to construct a survival prognostic model, divided melanoma patients into the training set, internal validation set 1, internal validation set 2, and external validation set for multiple validations, and discussed the correlation between model genes and clinical features of melanoma patients. In conclusion, we constructed a prognostic survival model based on TLR-related genes that precisely and independently demonstrated the potential to assess the prognosis and immune traits of melanoma patients, which is critical for patients' survival.

Palmitic acid combined with γ-interferon inhibits gastric cancer progression by modulating tumor-associated macrophages' polarization via the TLR4 pathway

BACKGROUND

Tumor-associated macrophages (TAMs) constitute the main infiltrating immune cells in the solid tumor microenvironment. Amounting studies have analyzed the antitumor effect on immune response induced by Toll-like receptor (TLR) agonists, such as lipopolysaccharide (LPS), γ-interferon (γ-IFN), and palmitic Acid (PA). However, their combined treatment for gastric cancer (GC) has not been illuminated.

METHODS

We investigated the relevance of macrophage polarization and the effect of PA and γ-IFN in GC in vitro and in vivo. M1 and M2 macrophage-associated markers were measured by real-time quantitative PCR and flow cytometry, and the activation level of the TLR4 signaling pathways was evaluated by western blot analysis. The effect of PA and γ-IFN on the proliferation, migration, and invasion of GC cells (GCCs) was evaluated by Cell-Counting Kit-8, transwell assays, and wound-healing assays. In vivo animal models were used to verify the effect of PA and γ-IFN on tumor progression, and the M1 and M2 macrophage markers, CD8 + T lymphocytes, regulatory T cells (Treg) cells, and the myeloid-derived suppressor cells (MDSCs) in tumor tissues were analyzed by flow cytometry and immunohistochemical (IHC).

RESULTS

The results showed that this combination strategy enhanced M1-like macrophages and diminished M2-like macrophages through the TLR4 signaling pathway in vitro. In addition, the combination strategy impairs the proliferative and migratory activity of GCC in vitro and in vivo. While, the antitumor effect was abolished using the TAK-424 (a specific TLR-4 signaling pathway inhibitor) in vitro.

CONCLUSIONS

The combined treatment of PA and γ-IFN inhibited GC progression by modulating macrophages polarization via the TLR4 pathway.

NOS inhibition reverses TLR2-induced chondrocyte dysfunction and attenuates age-related osteoarthritis

Osteoarthritis (OA) is a joint disease featuring cartilage breakdown and chronic pain. Although age and joint trauma are prominently associated with OA occurrence, the trigger and signaling pathways propagating their pathogenic aspects are ill defined. Following long-term catabolic activity and traumatic cartilage breakdown, debris accumulates and can trigger Toll-like receptors (TLRs). Here we show that TLR2 stimulation suppressed the expression of matrix proteins and induced an inflammatory phenotype in human chondrocytes. Further, TLR2 stimulation impaired chondrocyte mitochondrial function, resulting in severely reduced adenosine triphosphate (ATP) production. RNA-sequencing analysis revealed that TLR2 stimulation upregulated nitric oxide synthase 2 (NOS2) expression and downregulated mitochondria function-associated genes. NOS inhibition partially restored the expression of these genes, and rescued mitochondrial function and ATP production. Correspondingly, Nos2-/- mice were protected from age-related OA development. Taken together, the TLR2-NOS axis promotes human chondrocyte dysfunction and murine OA development, and targeted interventions may provide therapeutic and preventive approaches in OA.

Nanoengineered drug delivery in cancer immunotherapy for overcoming immunosuppressive tumor microenvironment

Almost like a living being in and of itself, tumors actively interact with and modify their environment to escape immune responses. Owing to the pre-formation of cancer-favorable microenvironment prior to anti-cancer treatment, the numerous attempts that followed propose limited efficacy in oncology. Immunogenicity by activation of immune cells within the tumor microenvironment or recruitment of immune cells from nearby lymph nodes is quickly offset as the immunosuppressive environment, rapidly converting immunogenic cells into immune suppressive cells, overriding the immune system. Tumor cells, as well as regulatory cells, namely M2 macrophages, Treg cells, and MDSCs, derived by the immunosuppressive environment, also cloak from potential anti-tumoral factors by directly or indirectly secreting cytokines, such as IL-10 and TGF-β, related to immune regulation. Enzymes and other metabolic or angiogenetic constituents - VEGF, IDO1, and iNOS - are also employed directed for anti-cancer immune cell malfunctioning. Therefore, the conversion of "cold" immunosuppressive environment into "hot" immune responsive environment is of paramount importance, bestowing the advances in the field of cancer immunotherapy the opportunity to wholly fulfill its intended purpose. This paper reviews the mechanisms by which tumors wield to exercise immune suppression and the nanoengineered delivery strategies being developed to overcome this suppression.

Pan-cancer analysis of TASL: a novel immune infiltration-related biomarker for tumor prognosis and immunotherapy response prediction

BACKGROUND

New immunotherapeutic strategies based on predictors are urgently needed. Toll-like receptor adaptor interacting with SLC15A4 on the lysosome (TASL) was recently confirmed to fulfill an important role in the innate immune response. However, whether TASL is involved in tumor development and immunotherapy response prediction has not been reported.

METHODS

TCGA and GTEx were used to yield transcriptional, genetic, and epigenetic levels of TASL in 33 cancer types. CIBERSORT was used to explore the correlation between TASL expression and multiple immune-related signatures and tumor-infiltrating immune cell content in different cancer types. The ability of TASL to predict tumor immunotherapy response was analyzed in seven datasets. Finally, we tested TASL expression in human glioma cell lines and tissue samples and analyzed its correlation with clinicopathological parameters.

RESULTS

TASL is widely heterogeneous at the transcriptional, genetic, and epigenetic levels. High TASL expression is an independent poor prognostic factor for immune "cold" tumor Low-Grade Glioma (LGG) but an opposite factor for "hot" tumors Lung Adenocarcinoma (LUAD) and Skin Cutaneous Melanoma (SKCM). TASL may affect tumor immune infiltration by mediating tumor-infiltrating lymphocytes and tumor-associated macrophages. It may differentially affect the prognosis of the three cancers by regulating the immunosuppressive microenvironment in LGG and the immunostimulatory microenvironment in LUAD and SKCM. High TASL expression is a potential biomarker for the positive response to immunotherapy in cancers such as SKCM and was also experimentally confirmed to be positively associated with adverse clinicopathological features of gliomas.

CONCLUSION

TASL expression is an independent prognostic factor for LGG, LUAD, and SKCM. High TASL expression is a potential biomarker for the positive response to immunotherapy in certain cancer types such as SKCM. Further basic studies focusing on TASL expression and tumor immunotherapy are urgently needed.

Pathomorphological Manifestations and the Course of the Cervical Cancer Disease Determined by Variations in the TLR4 Gene

Cervical cancer (CC) is often associated with human papillomavirus (HPV). Chronic inflammation has been described as one of the triggers of cancer. The immune system fights diseases, including cancer. The genetic polymorphism of pathogen recognition receptors potentially influences the infectious process, development, and disease progression. Many candidate genes SNPs have been contradictory demonstrated to be associated with cervical cancer by association studies, GWAS. TLR4 gene activation can promote antitumor immunity. It can also result in immunosuppression and tumor growth. Our study aimed to investigate eight selected polymorphisms of the TLR4 gene (rs10759932, rs1927906, rs11536898, rs11536865, rs10983755, rs4986790, rs4986791, rs11536897) and to determine the impact of polymorphisms in genotypes and alleles on the pathomorphological characteristics and progression in a group of 172 cervical cancer subjects with stage I-IV. Genotyping was performed by RT-PCR assay. We detected that the CA genotype and A allele of rs11536898 were significantly more frequent in patients with metastases (p = 0.026; p = 0.008). The multivariate logistic regression analysis confirmed this link to be significant. The effect of rs10759932 and rs11536898 on progression-free survival (PFS) and overall survival (OS) has been identified as important. In univariate and multivariate Cox analyses, AA genotype of rs11536898 was a negative prognostic factor for PFS (p = 0.024; p = 0.057, respectively) and OS (p = 0.008; p = 0.042, respectively). Rs11536898 C allele predisposed for longer PFS (univariate and multivariate: p = 0.025; p = 0.048, respectively) and for better OS (univariate and multivariate: p = 0.010; p = 0.043). The worse prognostic factor of rs10759932 in a univariate and multivariate Cox analysis for survival was CC genotype: shorter PFS (p = 0.032) and increased risk of death (p = 0.048; p = 0.015, respectively). The T allele of rs10759932 increased longer PFS (univariate and multivariate: p = 0.048; p = 0.019, respectively) and longer OS (univariate and multivariate: p = 0.037; p = 0.009, respectively). Our study suggests that SNPs rs10759932 and rs11536898 may have the potential to be markers contributing to the assessment of the cervical cancer prognosis. Further studies, preferably with larger groups of different ethnic backgrounds, are needed to confirm the results of the current study.

Building on the backbone of CD47-based therapy in cancer: Combination strategies, mechanisms, and future perspectives

Described as a "don't eat me" signal, CD47 becomes a vital immune checkpoint in cancer. Its interaction with signal regulatory protein alpha (SIRPα) prevents macrophage phagocytosis. In recent years, a growing body of evidences have unveiled that CD47-based combination therapy exhibits a superior anti-cancer effect. Latest clinical trials about CD47 have adopted the regimen of collaborating with other therapies or developing CD47-directed bispecific antibodies, indicating the combination strategy as a general trend of the future. In this review, clinical and preclinical cases about the current combination strategies targeting CD47 are collected, their underlying mechanisms of action are discussed, and ideas from future perspectives are shared.

Potential Role of Vaginal Microbiota in Ovarian Cancer Carcinogenesis, Progression and Treatment

Ovarian cancer represents one of the most challenging gynecologic cancers which still has numerous unknowns on the underlying pathogenesis. In addition to the verified contributors such as genomic predisposition and medical history in the carcinogenesis, emerging evidence points out the potential role of vaginal microbiota in ovarian cancer. Recent studies have underlined the presence of vaginal microbial dysbiosis in cancer cases. Increasing research also indicates the potential correlations between vaginal microbes and cancer carcinogenesis, progression and treatment. Currently, compared with other gynecologic cancers, reports on the roles of vaginal microbiota in ovarian cancer remain scarce and fragmentary. Therefore, in this review, we summarize the roles of vaginal microbiota in various gynecologic diseases, particularly focusing on the potential mechanisms and possible applications of vaginal microbiota in ovarian cancer, giving insight into the involvement of vaginal microbiota in gynecologic cancer treatment.

Applications and clinical trial landscape using Toll-like receptor agonists to reduce the toll of cancer

Toll-like receptors (TLRs), which serve as a bridge between innate and adaptive immunity, may be viable treatment targets. TLRs are the first line of defense against microbes and activate signaling cascades that induce immune and inflammatory responses. Patients with "hot" versus "cold" tumors may respond more favorably to immune checkpoint inhibition, and through their downstream effects, TLR agonists have the potential to convert "cold tumors" into "hot tumors" making TLRs in combination with immune checkpoint inhibitors, potential targets for cancer therapies. Imiquimod is a topical TLR7 agonist, approved by the FDA for antiviral and skin cancer treatments. Other TLR adjuvants are used in several vaccines including Nu Thrax, Heplisav, T-VEC, and Cervarix. Many TLR agonists are currently in development as both monotherapy and in combination with immune checkpoint inhibitors. In this review, we describe the TLR agonists that are being evaluated clinically as new therapies for solid tumors.

Research advances in nanomedicine applied to the systemic treatment of colorectal cancer

The systematic treatment of colorectal cancer (CRC) still has room for improvement. The efficacy of chemotherapy, that of anti-vascular therapy, and that of immunotherapy have been unsatisfactory. In recent years, nanomaterials have been used as carriers to improve the bioavailability of anticancer drugs. For the treatment of colorectal cancer, nanodrugs increase the possibility of more precise targeted delivery. However, the actual benefits may cover more aspects. Nanocarriers can produce synergistic effects with anticancer drugs, including the scavenging of reactive oxygen species and co-delivery of a variety of drugs. Currently, immunotherapy has very limited clinical applications in CRC. Modified nanocarriers can activate the immune microenvironment, which can be used for staging antigen recognition or the immune response. Cancer vaccines based on nanomaterials and modified immune checkpoint inhibitors have shown therapeutic potential in animal models. Considering the direct or indirect relationship between the intestinal microflora and CRC, a variety of nanodrugs that regulate microbial function have been explored as an anticancer strategy, and the special structure of microorganisms can also be used as a basis for improving the delivery of traditional nanoparticles (NPs). This review summarizes recent research performed on nanocarriers in in vivo and in vitro models and the synergistic anticancer effects of nanocarriers, focusing on the interaction between NPs and the body, resulting in enhanced efficacy and immune activation. Furthermore, this review describes the current trend of NPs used in the treatment of CRC.

Polymeric microneedles enable simultaneous delivery of cancer immunomodulatory drugs and detection of skin biomarkers

Background: Immune-modulating therapies impart positive outcomes in a subpopulation of cancer patients. Improved delivery strategies and non-invasive monitoring of anti-tumor effects can help enhance those outcomes and understand the mechanisms associated with the generation of anti-tumor immune responses following immunotherapy. Methods: We report on the design of a microneedle (MN) platform capable of simultaneous delivery of immune activators and collection of interstitial skin fluid (ISF) to monitor therapeutic responses. While either approach has shown promise, the integration of the therapy and diagnostic arms into one MN platform has hardly been explored before. MNs were synthesized out of crosslinked hyaluronic acid (HA) and loaded with a model immunomodulatory nanoparticle-containing drug, CpG oligodinucleotides (TLR9 agonist), for cancer therapy in melanoma and colon cancer models. The therapeutic response was monitored by longitudinal analysis of entrapped immune cells in the MNs following patch retrieval and digestion. Results: Transdermal delivery of CpG-containing NPs with MNs induced anti-tumor immune responses in multiple syngeneic mouse cancer models. CpG-loaded MNs stimulated innate immune cells and reduced tumor growth. Intravital microscopy showed deposition and spatiotemporal co-localization of CpG-NPs within the tumor microenvironment when delivered with MNs. Analysis of MN-sampled ISF revealed similar immune signatures to those seen in the bulk tumor homogenate, such as increased populations of macrophages and effector T cells following treatment. Conclusions: Our hydrogel-based MNs enable effective transdermal drug delivery into immune cells in the tumor microenvironment, and upon retrieval, enable studying the immune response to the therapy over time. This platform has the theranostic potential to deliver a range of combination therapies while detecting biomarkers.

Therapeutic Targeting of TLR4 for Inflammation, Infection, and Cancer: A Perspective for Disaccharide Lipid A Mimetics

The Toll-like receptor 4 (TLR4) signaling pathway plays a central role in the prompt defense against infectious challenge and provides immediate response to Gram-negative bacterial infection. The TLR4/MD-2 complex can sense and respond to various pathogen-associated molecular patterns (PAMPs) with bacterial lipopolysaccharide (LPS) being the most potent and the most frequently occurring activator of the TLR4-mediated inflammation. TLR4 is believed to be both a friend and foe since improperly regulated TLR4 signaling can result in the overactivation of immune responses leading to sepsis, acute lung injury, or pathologic chronic inflammation involved in cancer and autoimmune disease. TLR4 is also considered a legitimate target for vaccine adjuvant development since its activation can boost the adaptive immune responses. The dual action of the TLR4 complex justifies the efforts in the development of both TLR4 antagonists as antisepsis drug candidates or remedies for chronic inflammatory diseases and TLR4 agonists as vaccine adjuvants or immunotherapeutics. In this review, we provide a brief overview of the biochemical evidences for possible pharmacologic applications of TLR4 ligands as therapeutics and report our systematic studies on the design, synthesis, and immunobiological evaluation of carbohydrate-based TLR4 antagonists with nanomolar affinity for MD-2 as well as disaccharide-based TLR4 agonists with picomolar affinity for the TLR4/MD-2 complex.

Comprehensive analysis of the amino acid metabolism-related gene signature for prognosis, tumor immune microenvironment, and candidate drugs in hepatocellular carcinoma

Introduction

Metabolic rewiring satisfies increased nutritional demands and modulates many oncogenic processes in tumors. Amino acid metabolism is abnormal in many malignancies. Metabolic reprogramming of amino acids not only plays a crucial role in sustaining tumor cell proliferation but also influences the tumor immune microenvironment. Herein, the aim of our study was to elucidate the metabolic signature of amino acids in hepatocellular carcinoma (HCC).

Methods

Transcriptome profiles of HCC were obtained from the TCGA and ICGC databases. Based on the expression of amino acid metabolism-related genes (AAMRGs), we clustered the HCC samples into two molecular subtypes using the non-negative matrix factorization algorithm. Then, we constructed the amino acid metabolism-related gene signature (AAMRGS) by Cox regression and LASSO regression. Afterward, the clinical significance of the AAMRGS was evaluated. Additionally, we comprehensively analyzed the differences in mutational profiles, immune cell infiltration, immune checkpoint expression, and drug sensitivity between different risk subgroups. Furthermore, we examined three key gene expressions in liver cancer cells by quantitative real-time PCR and conducted the CCK8 assay to evaluate the influence of two chemotherapy drugs on different liver cancer cells.

Results

A total of 81 differentially expressed AAMRGs were screened between the two molecular subtypes, and these AAMRGs were involved in regulating amino acid metabolism. The AAMRGS containing GLS, IYD, and NQO1 had a high value for prognosis prediction in HCC patients. Besides this, the two AAMRGS subgroups had different genetic mutation probabilities. More importantly, the immunosuppressive cells were more enriched in the AAMRGS-high group. The expression level of inhibitory immune checkpoints was also higher in patients with high AAMRGS scores. Additionally, the two AAMRGS subgroups showed different susceptibility to chemotherapeutic and targeted drugs. In vitro experiments showed that gemcitabine significantly reduced the proliferative capacity of SNU449 cells, and rapamycin remarkedly inhibited Huh7 proliferation. The five HCC cells displayed different mRNA expression levels of GLS, IYD, and NQO1.

Conclusions

Our study explored the features of amino acid metabolism in HCC and identified the novel AAMRGS to predict the prognosis, immune microenvironment, and drug sensitivity of HCC patients. These findings might help to guide personalized treatment and improve the clinical outcomes of HCC.

The Tumor Microenvironment Reprograms Immune Cells

Tumor tissue comprises a highly complex network of diverse cell types. The tumor microenvironment (TME) can be mainly subdivided into cancer cells and stromal cell compartments, the latter include different types of immune cells, fibroblasts, endothelial cells, and pericytes. Tumor cells reprogram immune cells and other stromal cells in the TME to constrain their antitumor capacity by creating an immunosuppressive milieu and metabolism competition. Moreover, the reprogramming effect on immune cells is localized not only in the tumor but also at the systemic level. With wide application of single-cell sequencing technology, tumor-specific characteristics of immune cells and other stromal cells in the TME have been dissected. In this review, we mainly focus on how tumor cells reprogram immune cells both within the TME and peripheral blood. This information can further help us to improve the efficiency of current immunotherapy as well as bring up new ideas to combat cancer.

Qin Huang formula enhances the effect of Adriamycin in B-cell lymphoma via increasing tumor infiltrating lymphocytes by targeting toll-like receptor signaling pathway

Background

As an original traditional Chinese medicinal formula, Qin Huang formula (QHF) is used as adjuvant therapy for treating lymphoma in our hospital and has proven efficacy when combined with chemotherapy. However, the underlying mechanisms of QHF have not been elucidated.

Methods

A network pharmacological-based analysis method was used to screen the active components and predict the potential mechanisms of QHF in treating B cell lymphoma. Then, a murine model was built to verify the antitumor effect of QHF combined with Adriamycin (ADM) in vivo. Finally, IHC, ELISA, ¹⁸F-FDG PET-CT scan, and western blot were processed to reveal the intriguing mechanism of QHF in treating B cell lymphoma.

Results

The systemic pharmacological study revealed that QHF took effect following a multiple-target and multiple-pathway pattern in the human body. In vivo study showed that combination therapy with QHF and ADM potently inhibited the growth of B cell lymphoma in a syngeneic murine model, and significantly increased the proportion of tumor infiltrating CD4+ and CD8+ T cells in the tumor microenvironment (TME). Furthermore, the level of CXCL10 and IL-6 was significantly increased in the combination group. Finally, the western blot exhibited that the level of TLR2 and p38 MAPK increased in the combination therapy group.

Conclusion

QHF in combination of ADM enhances the antitumor effect of ADM via modulating tumor immune microenvironment and can be a combination therapeutic strategy for B cell lymphoma patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03660-8.

Advances in sex disparities for cancer immunotherapy: unveiling the dilemma of Yin and Yang

A wide sex disparity has been demonstrated in cancer incidence, tumor aggressiveness, prognosis, and treatment response of different types of cancer. The sex specificity of cancer appears to be a relevant issue in managing the disease, and studies investigating the role of sex and gender are becoming extremely urgent. Immunotherapy plays a leading role in cancer treatment, offering a new perspective on advanced malignancies. Gender has not been considered in standard cancer treatment, suggesting increasing the recognition of sex differences in cancer research and clinical management. This paper provides an overview of sex and gender disparities in cancer immunotherapy efficacy, anti-cancer immune response, predictive biomarkers, and so on. We focus on the molecular differences between male and female patients across a broad range of cancer types to arouse the attention and practice of clinicians and researchers in a sex perspective of new cancer treatment strategies.

Sex differences exist in the prevalence, tumor invasiveness, treatment responses, and clinical outcomes of pan-cancer, suggesting that, while not yet incorporated, sex will probably be considered in future practice guidelines.

Inherent genetic differences, overlapping epigenetic alterations, and sex hormone influences underpin everything. Androgen receptors influence the sexual differences in TME by regulating epigenetic and transcriptional differentiation programs. It highlights a sex-based therapeutic target for cancer immunotherapy.

Proper consideration of sex, age, sex hormones/menopause status, and socio-cultural gender differences in clinical investigation and gene association studies of cancer are needed to fill current gaps and implement precision medicine for patients with cancer.

Hyaluronic Acid: A Review of the Drug Delivery Capabilities of This Naturally Occurring Polysaccharide

The inclusion of physiologically active molecules into a naturally occurring polymer matrix can improve the degradation, absorption, and release profile of the drug, thus boosting the therapeutic impact and potentially even reducing the frequency of administration. The human body produces significant amounts of polysaccharide hyaluronic acid, which boasts exceptional biocompatibility, biodegradability, and one-of-a-kind physicochemical features. In this review, we will examine the clinical trials currently utilizing hyaluronic acid and address the bright future of this versatile polymer, as well as summarize the numerous applications of hyaluronic acid in drug delivery and immunomodulation.

Targeting macrophages in hematological malignancies: recent advances and future directions

Emerging evidence indicates that the detection and clearance of cancer cells via phagocytosis induced by innate immune checkpoints play significant roles in tumor-mediated immune escape. The most well-described innate immune checkpoints are the "don't eat me" signals, including the CD47/signal regulatory protein α axis (SIRPα), PD-1/PD-L1 axis, CD24/SIGLEC-10 axis, and MHC-I/LILRB1 axis. Molecules have been developed to block these pathways and enhance the phagocytic activity against tumors. Several clinical studies have investigated the safety and efficacy of CD47 blockades, either alone or in combination with existing therapy in hematological malignancies, including myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and lymphoma. However, only a minority of patients have significant responses to these treatments alone. Combining CD47 blockades with other treatment modalities are in clinical studies, with early results suggesting a synergistic therapeutic effect. Targeting macrophages with bispecific antibodies are being explored in blood cancer therapy. Furthermore, reprogramming of pro-tumor macrophages to anti-tumor macrophages, and CAR macrophages (CAR-M) demonstrate anti-tumor activities. In this review, we elucidated distinct types of macrophage-targeted strategies in hematological malignancies, from preclinical experiments to clinical trials, and outlined potential therapeutic approaches being developed.

Therapeutic applications of toll-like receptors (TLRs) agonists in AML

Acute myeloid leukemia (AML) is an aggressive type of blood cancer affecting bone marrow (BM). In AML, hematopoietic precursors are arrested in the early stages of development and are defined as the presence of ≥ 20% blasts (leukemia cells) in the BM. Toll-like receptors (TLR) are major groups of pattern recognition receptors expressed by almost all innate immune cells that enable them to detect a wide range of pathogen-associated molecular patterns and damage-associated molecular patterns to prime immune responses toward adaptive immunity. Because TLRs are commonly expressed on transformed immune system cells (ranging from blasts to memory cells), they can be a potential option for developing efficient clinical alternatives in hematologic tumors. This is because several in vitro and in vivo investigations have demonstrated that TLR signaling increased the immunogenicity of AML cells, making them more vulnerable to T cell-mediated invasion. This study aimed to review the current knowledge in this field and provide some insight into the therapeutic potentials of TLRs in AML.

Metabolic profiles of regulatory T cells and their adaptations to the tumor microenvironment: implications for antitumor immunity

Characterized by the expression of the critical transcription factor forkhead box protein P3, regulatory T (Treg) cells are an essential part of the immune system, with a dual effect on the pathogenesis of autoimmune diseases and cancer. Targeting Tregs to reestablish the proinflammatory and immunogenic tumor microenvironment (TME) is an increasingly attractive strategy for cancer treatment and has been emphasized in recent years. However, attempts have been significantly hindered by the subsequent autoimmunity after Treg ablation owing to systemic loss of their suppressive capacity. Cellular metabolic reprogramming is acknowledged as a hallmark of cancer, and emerging evidence suggests that elucidating the underlying mechanisms of how intratumoral Tregs acquire metabolic fitness and superior immunosuppression in the TME may contribute to clinical benefits. In this review, we discuss the common and distinct metabolic profiles of Tregs in peripheral tissues and the TME, as well as the differences between Tregs and other conventional T cells in their metabolic preferences. By focusing on the critical roles of different metabolic programs, such as glycolysis, oxidative phosphorylation, fatty acid oxidation, fatty acid synthesis, and amino acid metabolism, as well as their essential regulators in modulating Treg proliferation, migration, and function, we hope to provide new insights into Treg cell-targeted antitumor immunotherapies.

Glucometabolic reprogramming: From trigger to therapeutic target in hepatocellular carcinoma

Glucose, the central macronutrient, releases energy as ATP through carbon bond oxidation and supports various physiological functions of living organisms. Hepatocarcinogenesis relies on the bioenergetic advantage conferred by glucometabolic reprogramming. The exploitation of reformed metabolism induces a uniquely inert environment conducive to survival and renders the hepatocellular carcinoma (HCC) cells the extraordinary ability to thrive even in the nutrient-poor tumor microenvironment. The rewired metabolism also confers a defensive barrier which protects the HCC cells from environmental stress and immune surveillance. Additionally, targeted interventions against key players of HCC metabolic and signaling pathways provide promising prospects for tumor therapy. The active search for novel drugs based on innovative mutation targets is warranted in the future for effectively treating advanced HCC and the preoperative downstage. This article aims to review the regulatory mechanisms and therapeutic value of glucometabolic reprogramming on the disease progression of HCC, to gain insights into basic and clinical research.

Context-dependent functions of pattern recognition receptors in cancer

The immune system plays a critical role in shaping all facets of cancer, from the early initiation stage through to metastatic disease and resistance to therapy. Our understanding of the importance of the adaptive arm of the immune system in antitumour immunity has led to the implementation of immunotherapy with immune checkpoint inhibitors in numerous cancers, albeit with differing efficacy. By contrast, the clinical utility of innate immunity in cancer has not been exploited, despite dysregulated innate immunity being a feature of at least one-third of all cancers associated with tumour-promoting chronic inflammation. The past two decades have seen innate immune pattern recognition receptors (PRRs) emerge as critical regulators of the immune response to microbial infection and host tissue damage. More recently, it has become apparent that in many cancer types, PRRs play a central role in modulating a vast array of tumour-inhibiting and tumour-promoting cellular responses both in immune cells within the tumour microenvironment and directly in cancer cells. Herein, we provide a comprehensive overview of the fast-evolving field of PRRs in cancer, and discuss the potential to target PRRs for drug development and biomarker discovery in a wide range of oncology settings.

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.

Targeted inhibition of STAT3 induces immunogenic cell death of hepatocellular carcinoma cells via glycolysis

In hepatocellular carcinoma (HCC), the signal transducer and activator of transcription 3 (STAT3) is present in an overactive state that is closely related to tumour development and immune escape. STAT3 inhibition reshapes the tumour immune microenvironment, but the underlying mechanisms have not been fully clarified. We found that STAT3 inhibition could induce immunogenic cell death (ICD) of HCC cells via translocation of the “eat me” molecule calreticulin to the cell surface and a significant reduction in the expression of the “don’t eat me” molecule leucocyte surface antigen CD47. STAT3 inhibition promoted dendritic cell (DC) activation and enhanced the recognition and phagocytosis of HCC cells by macrophages. Furthermore, STAT3 inhibition prevented the expression of key glycolytic enzymes, facilitating the induction of ICD in HCC. Interestingly, STAT3 directly regulated the transcription of CD47 and solute carrier family 2 member 1 (SLC2A1; also known as GLUT1). In subcutaneous and orthotopic transplantation mouse tumour models, the STAT3 inhibitor napabucasin prevented tumour growth and induced the expression of calreticulin and the protein disulfide isomerase family A member 3 (PDIA3; also known as ERp57) but suppressed that of CD47 and GLUT1. Meanwhile, the amount of tumour‐infiltrated DCs and macrophages increased, along with the expression of costimulatory molecules. More CD4⁺ and CD8⁺ T cells accumulated in tumour tissues, and CD8⁺ T cells had lower expression of checkpoint molecules such as lymphocyte activation gene 3 protein (LAG‐3) and programmed cell death protein 1 (PD‐1). Significantly, the antitumour immune memory response was induced by treatment targeting STAT3. These findings provide a new mechanism for targeting STAT3‐induced ICD in HCC, and confirms STAT3 as a potential target for the treatment of HCC via reshaping the tumour immune microenvironment.

Targeting the Tumor Microenvironment: A Close Up of Tumor-Associated Macrophages and Neutrophils

The importance of the tumor microenvironment (TME) in dynamically regulating cancer progression and influencing the therapeutic outcome is widely accepted and appreciated. Several therapeutic strategies to modify or modulate the TME, like angiogenesis or immune checkpoint inhibitors, showed clinical efficacy and received approval from regulatory authorities. Within recent decades, new promising strategies targeting myeloid cells have been implemented in preclinical cancer models. The predominance of specific cell phenotypes in the TME has been attributed to pro- or anti-tumoral. Hence, their modulation can, in turn, alter the responses to standard-of-care treatments, making them more or less effective. Here, we summarize and discuss the current knowledge and the correlated challenges about the tumor-associated macrophages and neutrophils targeting strategies, current treatments, and future developments.

Targeting oncometabolism to maximize immunotherapy in malignant brain tumors

Brain tumors result in significant morbidity and mortality in both children and adults. Recent data indicates that immunotherapies may offer a survival benefit after standard of care has failed for malignant brain tumors. Modest results from several late phase clinical trials, however, underscore the need for more refined, comprehensive strategies that incorporate new mechanistic and pharmacologic knowledge. Recently, oncometabolism has emerged as an adjunct modality for combinatorial treatment approaches necessitated by the aggressive, refractory nature of high-grade glioma and other progressive malignant brain tumors. Manipulation of metabolic processes in cancer and immune cells that comprise the tumor microenvironment through controlled targeting of oncogenic pathways may be utilized to maximize the efficacy of immunotherapy and improve patient outcomes. Herein, we summarize preclinical and early phase clinical trial research of oncometabolism-based therapeutics that may augment immunotherapy by exploiting the biochemical and genetic underpinnings of brain tumors. We also examine metabolic pathways related to immune cells that target tumor cells, termed ‘tumor immunometabolism’. Specifically, we focus on glycolysis and altered glucose metabolism, including glucose transporters, hexokinase, pyruvate dehydrogenase, and lactate dehydrogenase, glutamine, and we discuss targeting arginase, adenosine, and indoleamine 2,3-dioxygenase (IDO), and toll-like receptors. Lastly, we summarize future directions targeting metabolism in combination with emerging therapies such as oncolytic virotherapy, vaccines, and chimeric antigen receptor T cells.

Modulation of TLR/NF-κB/NLRP Signaling by Bioactive Phytocompounds: A Promising Strategy to Augment Cancer Chemotherapy and Immunotherapy

Background

Tumors often progress to a more aggressive phenotype to resist drugs. Multiple dysregulated pathways are behind this tumor behavior which is known as cancer chemoresistance. Thus, there is an emerging need to discover pivotal signaling pathways involved in the resistance to chemotherapeutic agents and cancer immunotherapy. Reports indicate the critical role of the toll-like receptor (TLR)/nuclear factor-κB (NF-κB)/Nod-like receptor pyrin domain-containing (NLRP) pathway in cancer initiation, progression, and development. Therefore, targeting TLR/NF-κB/NLRP signaling is a promising strategy to augment cancer chemotherapy and immunotherapy and to combat chemoresistance. Considering the potential of phytochemicals in the regulation of multiple dysregulated pathways during cancer initiation, promotion, and progression, such compounds could be suitable candidates against cancer chemoresistance.

Objectives

This is the first comprehensive and systematic review regarding the role of phytochemicals in the mitigation of chemoresistance by regulating the TLR/NF-κB/NLRP signaling pathway in chemotherapy and immunotherapy.

Methods

A comprehensive and systematic review was designed based on Web of Science, PubMed, Scopus, and Cochrane electronic databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to include papers on TLR/NF-κB/NLRP and chemotherapy/immunotherapy/chemoresistance by phytochemicals.

Results

Phytochemicals are promising multi-targeting candidates against the TLR/NF-κB/NLRP signaling pathway and interconnected mediators. Employing phenolic compounds, alkaloids, terpenoids, and sulfur compounds could be a promising strategy for managing cancer chemoresistance through the modulation of the TLR/NF-κB/NLRP signaling pathway. Novel delivery systems of phytochemicals in cancer chemotherapy/immunotherapy are also highlighted.

Conclusion

Targeting TLR/NF-κB/NLRP signaling with bioactive phytocompounds reverses chemoresistance and improves the outcome for chemotherapy and immunotherapy in both preclinical and clinical stages.

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.

(Im)maturity in Tumor Ecosystem

Tumors have special features that make them distinct from their normal counterparts. Immature cells in a tumor mass and their critical contributions to the tumorigenesis will open new windows toward cancer therapy. Incomplete cellular development brings versatile and unique functionality in the cellular tumor ecosystem, such as what is seen for highly potential embryonic cells. There is evidence that maturation of certain types of cells in this ecosystem can recover the sensitivity of the tumor. Therefore, understanding more about the mechanisms that contributed to this immaturity will render new therapeutic approaches in cancer therapy. Targeting such mechanisms can be exploited as a supplementary to the current immunotherapeutic treatment schedules, such as immune checkpoint inhibitor (ICI) therapy. The key focus of this review is to discuss the impact of (im)maturity in cellular tumor ecosystems on cancer progression, focusing mainly on immaturity in the immune cell compartment of the tumor, as well as on the stemness of tumor cells.

Toll-Like Receptors (TLRs) in Health and Disease: An Overview

Toll-like receptors were discovered as proteins playing a crucial role in the dorsoventral patterning during embryonic development in the Drosophila melanogaster (D. melanogaster) almost 40 years ago. Subsequently, further research also showed a role of the Toll protein or Toll receptor in the recognition of Gram-positive bacterial and fungal pathogens infecting D. melanogaster. In 1997, the human homolog was reported and the receptor was named the Toll-like receptor 4 (TLR4) that recognizes lipopolysaccharide (LPS) of the Gram-negative bacteria as a pathogen-associated molecular pattern (PAMP). Identification of TLR4 in humans filled the long existing gap in the field of infection and immunity, addressing the mystery surrounding the recognition of foreign pathogens/microbes by the immune system. It is now known that mammals (mice and humans) express 13 different TLRs that are expressed on the outer cell membrane or intracellularly, and which recognize different PAMPs or microbe-associated molecular patterns (MAMPs) and death/damage-associated molecular patterns (DAMPs) to initiate the protective immune response. However, their dysregulation generates profound and prolonged pro-inflammatory immune responses responsible for different inflammatory and immune-mediated diseases. This chapter provides an overview of TLRs in the control of the immune response, their association with different diseases, including TLR single nucleotide polymorphisms (SNPs), interactions with microRNAs (miRs), use in drug development and vaccine design, and expansion in neurosciences to include pain, addiction, metabolism, reproduction, and wound healing.