Toll-like receptors (TLRs): An old family of immune receptors with a new face in cancer pathogenesis

Deletion of the alr gene in Brucella suis S2 attenuates virulence by enhancing TLR4-NF-κB-NLRP3- mediated host inflammatory responses

Brucella is an intracellular parasitic bacterium lacking typical virulence factors, and its pathogenicity primarily relies on replication within host cells. In this study, we observed a significant increase in spleen weight in mice immunized with a Brucella strain deleted of the gene for alanine racemase (Alr), the enzyme responsible for alanine racemization (Δalr). However, the bacterial load in the spleen markedly decreased in the mutant strain. Concurrently, the ratio of white pulp to red pulp in the spleen was increased, serum IgG levels were elevated, but no significant damage to other organs was observed. In addition, the inflammatory response was potentiated and the NF-κB-NLRP3 signaling pathway was activated in macrophages (RAW264.7 Cells and Bone Marrow-Derived Cells) infect ed with the Δalr mutant. Further investigation revealed that the Δalr mutant released substantial amounts of protein in a simulated intracellular environment which resulted in heightened inflammation and activation of the TLR4-NF-κB-NLRP3 pathway in macrophages. The consequent cytoplasmic exocytosis reduced intracellular Brucella survival. In summary, cytoplasmic exocytosis products resulting from infection with a Brucella strain deleted of the alr gene effectively activated the TLR4-NFκB-NLRP3 pathway, triggered a robust inflammatory response, and reduced bacterial survival within host cells. Moreover, the Δalr strain exhibits lower toxicity and stronger immunogenicity in mice.

Sex-related immunity: could Toll-like receptors be the answer in acute inflammatory response?

An increasing number of studies have highlighted the existence of a sex-specific immune response, wherein men experience a worse prognosis in cases of acute inflammatory diseases. Initially, this sex-dependent inflammatory response was attributed to the influence of sex hormones. However, a growing body of evidence has shifted the focus toward the influence of chromosomes rather than sex hormones in shaping these inflammatory sex disparities. Notably, certain pattern recognition receptors, such as Toll-like receptors (TLRs), and their associated immune pathways have been implicated in driving the sex-specific immune response. These receptors are encoded by genes located on the X chromosome. TLRs are pivotal components of the innate immune system, playing crucial roles in responding to infectious diseases, including bacterial and viral pathogens, as well as trauma-related conditions. Importantly, the TLR-mediated inflammatory responses, as indicated by the production of specific proteins and cytokines, exhibit discernible sex-dependent patterns. In this review, we delve into the subject of sex bias in TLR activation and explore its clinical implications relatively to both the X chromosome and the hormonal environment. The overarching objective is to enhance our understanding of the fundamental mechanisms underlying these sex differences.

Analysis of Selected Toll-like Receptors in the Pathogenesis and Advancement of Non-Small-Cell Lung Cancer

(1) Background: Non-small-cell lung cancer (NSCLC) represents a significant global health challenge, contributing to numerous cancer deaths. Despite advances in diagnostics and therapy, identifying reliable biomarkers for prognosis and therapeutic stratification remains difficult. Toll-like receptors (TLRs), crucial for innate immunity, now show potential as contributors to cancer development and progression. This study aims to investigate the role of TLR expression as potential biomarkers in the development and progression of NSCLC. (2) Materials and Methods: The study was conducted on 89 patients diagnosed with NSCLC and 40 healthy volunteers, for whom the prevalence of TLR2, TLR3, TLR4, TLR7, TLR8, and TLR9 was assessed on selected subpopulations of T and B lymphocytes in the peripheral blood of recruited patients along with the assessment of their serum concentration. (3) Result: Our study showed several significant changes in NSCLC patients at the beginning of the study. This resulted in a 5-year follow-up of changes in selected TLRs in recruited patients. Due to the high mortality rate of NSCLC patients, only 16 patients survived the 5 years. (4) Conclusions: The results suggest that TLRs may constitute real biomarker molecules that may be used for future prognostic purposes in NSCLC. However, further validation through prospective clinical and functional studies is necessary to confirm their clinical utility. These conclusions may lead to better risk stratification and tailored interventions, benefiting NSCLC patients and bringing medicine closer to precision.

Structure-Based Design and Synthesis of Lipid A Derivatives to Modulate Cytokine Responses

Agonists of Toll like receptors (TLRs) have attracted interest as adjuvants and immune modulators. A crystal structure of TLR4/MD2 with E. coli LPS indicates that the fatty acid at C-2 of the lipid A component of LPS induces dimerization of two TLR4-MD2 complexes, which in turn initiates cell signaling leading to the production of (pro)inflammatory cytokines. To probe the importance of the (R)-3-hydroxymyristate at C-2 of lipid A, a range of bis- and mono-phosphoryl lipid A derivatives with different modifications at C-2 were prepared by a strategy in which 2-methylnaphthyl ethers were employed as permanent protecting group that could be readily removed by catalytic hydrogenation. The C-2 amine was protected as 9-fluorenylmethyloxycarbamate, which at a later stage could be removed to give a free amine that was modified by different fatty acids. LPS and the synthetic lipid As induced the same cytokines, however, large differences in activity were observed. A compound having a hexanoyl moiety at C-2 still showed agonistic properties, but further shortening to a butanoyl abolished activity. The modifications had a larger influence on monophosphoryl lipid As. The lipid As having a butanoyl moiety at C-2 could selectively antagonize TRIF associated cytokines induced by LPS or lipid A.

Toll-like receptor 6 inhibits colorectal cancer progression by suppressing NF-κB signaling

Background

Toll-like receptors (TLRs) are implicated in the pathogenesis and progression of inflammation-associated cancers, except their role in regulating innate immunity. Specifically, a berrant expression of TLR6 has been observed in colorectal cancers (CRC). However, the effect of abnormal TLR6 expression on CRC remians unclear. Therefore, the present study evaluated TLR6 expression in CRC, its effect on CRC proliferation, and its underlying mechanism.

Methods

The expression of TLR6 in CRC was assessed using data from TCGA, GTEx, and HPA datasets and immunohistochemical assays of tumor tissues from patients with CRC. In human CRC cell lines, TLR6 signaling was activated using the TLR6 agonist Pam2CSK4 and was blocked using antiTLR6-IgG; subsequently, cell growth, migration, invasion, cell cycle, and apoptosis were compared in CRC cells. The levels of the anti-apoptotic protein Bcl-2 and the apoptotic protein Bax were identified using western blotting. In addition, the effect of TLR6 knockdown by shRNAs in CRC cells was observed both in vitro and in vivo. Nuclear factor κB (NF-κB) level was evaluated using immunofluorescence and western bolt.

Results

TLR6 expression was significantly downregulated in CRC tissues. The activation of TLR6 by Pam2CSK4 (100 pg/mL to 10 ng/mL) inhibited the proliferation of CRC cells. Compared with blocking TLR6 signaling using antiTLR6-IgG, activating TLR6 signaling significantly inhibited CRC cell growth, migration, and invasion as well as decreased the proportion of cells in the S and G2/M phases and promoted apoptosis. Furthermore, the knockdown of TLR6 by shRNA promoted the biological activity of CRC cells both in vitro and in vivo. Moreover, the activation of TLR6 signaling by Pam2CSK4 significantly downregulated NF-κB and Bcl-2 levels but upregulated Bax levels.

Conclusion

The findings of this study demonstrate that TLR6 may play a inhibitive role in CRC tumorigenesis by suppressing the activity of NF-κB signaling.

Recent advances in different interactions between toll-like receptors and hepatitis B infection: a review

Hepatitis B virus (HBV) B infections remain a primary global health concern. The immunopathology of the infection, specifically the interactions between HBV and the host immune system, remains somewhat unknown. It has been discovered that innate immune reactions are vital in eliminating HBV. Toll-like receptors (TLRs) are an essential category of proteins that detect pathogen-associated molecular patterns (PAMPs). They begin pathways of intracellular signals to stimulate pro-inflammatory and anti-inflammatory cytokines, thus forming adaptive immune reactions. HBV TLRs include TLR2, TLR3, TLR4, TLR7 and TLR9. Each TLR has its particular molecule to recognize; various TLRs impact HBV and play distinct roles in the pathogenesis of the disease. TLR gene polymorphisms may have an advantageous or disadvantageous efficacy on HBV infection, and some single nucleotide polymorphisms (SNPs) can influence the progression or prognosis of infection. Additionally, it has been discovered that similar SNPs in TLR genes might have varied effects on distinct populations due to stress, diet, and external physical variables. In addition, activation of TLR-interceded signaling pathways could suppress HBV replication and increase HBV-particular T-cell and B-cell reactions. By identifying these associated polymorphisms, we can efficiently advance the immune efficacy of vaccines. Additionally, this will enhance our capability to forecast the danger of HBV infection or the threat of dependent liver disease development via several TLR SNPs, thus playing a role in the inhibition, monitoring, and even treatment guidance for HBV infection. This review will show TLR polymorphisms, their influence on TLR signaling, and their associations with HBV diseases.

Toll-like receptor 7 and tumor necrosis factor alpha polymorphisms in Egyptian patients with autoimmune thyroid diseases

Hashimoto's thyroiditis (HT) and Graves' disease (GD) susceptibility depends on a complex interaction between environmental and genetic factors. Genes for tumor necrosis factor alpha (TNF-α) and toll-like receptors (TLRs) have been incorporated into the pathophysiology of autoimmune disorders. Our aim is to assess the association between TLR7 (rs179009) and TNF-α (rs1800629) polymorphisms and susceptibility to autoimmune thyroid disorders. One-hundred ninety-nine individuals, divided into 68 HT patients in group I, 57 GD patients in group II, and 74 age- and gender-matched healthy subjects in group III, underwent laboratory investigations, including the detection of TLR7 and TNF-α polymorphisms using real-time PCR technique. TLR7 (rs179009) genotypes, A/G and G/G, were significantly more prevalent in HT patients (group I) compared to normal controls. Meanwhile, TNF-α (rs1800629) genotypes in GD patients (group II) showed a six fold increase in the risk of the disease in the G/A and A/A genotypes. Our findings propose the fact that the polymorphisms of TLR7 (rs179009) play a role in the susceptibility and the development of Hashimoto's thyroiditis, whereas TNF-α (rs1800629) polymorphisms play a role in the susceptibility and development of Graves' disease.

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

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

Exploring TLR signaling pathways as promising targets in cervical cancer: The road less traveled

Cervical cancer is the leading cause of cancer-related deaths for women globally. Despite notable advancements in prevention and treatment, the identification of novel therapeutic targets remains crucial for cervical cancer. Toll-like receptors (TLRs) play an essential role in innate immunity as pattern-recognition receptors. There are several types of pathogen-associated molecular patterns (PAMPs), including those present in cervical cancer cells, which have the ability to activate toll-like receptors (TLRs). Recent studies have revealed dysregulated toll-like receptor (TLR) signaling pathways in cervical cancer, leading to the production of inflammatory cytokines and chemokines that can facilitate tumor growth and metastasis. Consequently, TLRs hold significant promise as potential targets for innovative therapeutic agents against cervical cancer. This book chapter explores the role of TLR signaling pathways in cervical cancer, highlighting their potential for targeted therapy while addressing challenges such as tumor heterogeneity and off-target effects. Despite these obstacles, targeting TLR signaling pathways presents a promising approach for the development of novel and effective treatments for cervical cancer.

Combination Therapy with a TLR7 Agonist and a BRD4 Inhibitor Suppresses Tumor Growth via Enhanced Immunomodulation

JQ-1 is a typical BRD4 inhibitor with the ability to directly fight tumor cells and evoke antitumor immunity via reducing the expression of PD-L1. However, problems arise with the development of JQ-1 in clinical trials, such as marked lymphoid and hematopoietic toxicity, leading to the investigation of combination therapy. SZU-101 is a TLR7 agonist designed and synthesized by our group with potent immunostimulatory activity. Therefore, we hypothesized that combination therapy of SZU-101 and JQ-1 would target innate immunity and adaptive immunity simultaneously, to achieve a better antitumor efficacy than monotherapy. In this study, the repressive effects of the combination administration on tumor growth and metastasis were demonstrated in both murine breast cancer and melanoma models. In 4T1 tumor-bearing mice, i.t. treatment with SZU-101 in combination with i.p. treatment with JQ-1 suppressed the growth of tumors at both injected and uninjected sites. Combination therapy increased M1/M2 ratio in TAMs, decreased PD-L1 expression and promoted the recruitment of activated CD8+ T cells in the TME. In summary, the improved therapeutic efficacy of the novel combination therapy appears to be feasible for the treatment of a diversity of cancers.

Generation of porcine PK-15 cells lacking the Ifnar1 or Stat2 gene to optimize the efficiency of viral isolation

Because pigs are intermediate or amplifying hosts for several zoonotic viruses, the pig-derived PK-15 cell line is an indispensable tool for studying viral pathogenicity and developing treatments, vaccines, and preventive measures to mitigate the risk of disease outbreaks. However, we must consider the possibility of contamination by type I interferons (IFNs), such as IFNα and IFNβ, or IFN-inducing substances, such as virus-derived double-stranded RNA or bacterial lipopolysaccharides, in clinical samples, leading to lower rates of viral isolation. In this study, we aimed to generate a PK-15 cell line that can be used to isolate viruses from clinical samples carrying a risk of contamination by IFN-inducing substances. To this end, we depleted the IFN alpha and beta receptor subunit 1 (Ifnar1) gene or signal transducer and activator of transcription 2 (Stat2) gene in PK-15 cells using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 method. Treatment of PK-15 cells lacking Ifnar1 or Stat2 with IFNβ or poly (I:C) resulted in no inhibitory effects on viral infection by a lentiviral vector, influenza virus, and Akabane virus. These results demonstrate that PK-15 cells lacking Ifnar1 or Stat2 could represent a valuable and promising tool for viral isolation, vaccine production, and virological investigations.

Necrotic Cells from Head and Neck Carcinomas Release Biomolecules That Are Activating Toll-like Receptor 3

Tumor necrosis is a recurrent characteristic of head and neck squamous cell carcinomas (HNSCCs). There is a need for more investigations on the influence of biomolecules released by these necrotic foci in the HNSCC tumor microenvironment. It is suspected that a fraction of the biomolecules released by necrotic cells are damage-associated molecular patterns (DAMPs), which are known to be natural endogenous ligands of Toll-like receptors (TLRs), including, among others, proteins and nucleic acids. However, there has been no direct demonstration that biomolecules released by HNSCC necrotic cells can activate TLRs. Our aim was to investigate whether some of these molecules could behave as agonists of the TLR3, either in vitro or in vivo. We chose a functional approach based on reporter cell exhibiting artificial TLR3 expression and downstream release of secreted alkaline phosphatase. The production of biomolecules activating TLR3 was first investigated in vitro using three HNSCC cell lines subjected to various pronecrotic stimuli (external irradiation, serum starvation, hypoxia and oxidative stress). TLR3 agonists were also investigated in necrotic tumor fluids from five oral cancer patients and three mouse tumor grafts. The release of biomolecules activating TLR3 was demonstrated for all three HNSCC cell lines. External irradiation was the most consistently efficient stimulus, and corresponding TLR3 agonists were conveyed in extracellular vesicles. TLR3-stimulating activity was detected in the fluids from all five patients and three mouse tumor grafts. In most cases, this activity was greatly reduced by RNAse pretreatment or TLR3 blocking antibodies. Our data indicate that TLR3 agonists are consistently present in necrotic fluids from HNSCC cells and mainly made of dsRNA fragments. These endogenous agonists may induce TLR3, which might lead to a protumorigenic effect. Regarding methodological aspects, our study demonstrates that direct investigations-including functional testing-can be performed on necrotic fluids from patient tumors.

In-vitro Modulation of mTOR-HIF-1α Axis by TLR7/8 Agonist (Resiquimod) in B-Chronic Lymphocytic Leukemia

Targeting toll-like receptors (TLRs), via TLR agonists, has been implicated in the regulation of immunometabolism. B-chronic lymphocytic leukemia (B-CLL) represents a suitable model for B-cell derived malignancies with shifted metabolic adaptations. Several signaling pathways have been found to be critical in metabolic reprogramming of CLL, including mechanistic target of rapamycin- hypoxia inducible factor-1α (mTOR- HIF-1α) pathway, the main metabolic regulator of glycolysis. Here, we investigated the effect of TLR7/8 agonist (Resiquimod) on the expression of mTOR and HIF-1α in patients with CLL. B cells were purified using Rosettesep Human B cell Enrichment Cocktail (Stem cell Technologies, Vancouver, BC, Canada#15,024) from peripheral venous blood of CLL patients (n = 20) and healthy individuals (n = 15). Isolated B cells were then cultured in both presence and absence of Resiquimod. Gene expression of mTOR and HIF-1α were assessed using qRT-PCR. Resiquimod significantly decreased mTOR and HIF-1α gene expression in both CLL (p < 0.001and p < 0.001, respectively) and Normal B cells (p = 0.004 and p = 0.001, respectively). Resiquimod may reprogram immunometabolism of malignant B-CLL cells via down-regulation of key glycolytic metabolic actors, mTOR and HIF-1α genes. Accordingly, Resiquimod may be an adjuvant as a therapeutic tool for CLL, which needs to be studied further.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01649-y.

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.

Gut microbiota-derived short-chain fatty acids promote prostate cancer progression via inducing cancer cell autophagy and M2 macrophage polarization

We have previously demonstrated abnormal gut microbial composition in castration-resistant prostate cancer (CRPC) patients, here we revealed the mechanism of gut microbiota-derived short-chain fatty acids (SCFAs) as a mediator linking CRPC microbiota dysbiosis and prostate cancer (PCa) progression. By using transgenic TRAMP mouse model, PCa patient samples, in vitro PCa cell transwell and macrophage recruitment assays, we examined the effects of CRPC fecal microbiota transplantation (FMT) and SCFAs on PCa progression. Our results showed that FMT with CRPC patients' fecal suspension increased SCFAs-producing gut microbiotas such as Ruminococcus, Alistipes, Phascolarctobaterium in TRAMP mice, and correspondingly raised their gut SCFAs (acetate and butyrate) levels. CRPC FMT or SCFAs supplementation significantly accelerated mice's PCa progression. In vitro, SCFAs enhanced PCa cells migration and invasion by inducing TLR3-triggered autophagy that further activated NF-κB and MAPK signalings. Meanwhile, autophagy of PCa cells released higher level of chemokine CCL20 that could reprogramme the tumor microenvironment by recruiting more macrophage infiltration and simultaneously polarizing them into M2 type, which in turn further strengthened PCa cells invasiveness. Finally in a cohort of 362 PCa patients, we demonstrated that CCL20 expression in prostate tissue was positively correlated with Gleason grade, pre-operative PSA, neural/seminal vesical invasion, and was negatively correlated with post-operative biochemical recurrence-free survival. Collectively, CRPC gut microbiota-derived SCFAs promoted PCa progression via inducing cancer cell autophagy and M2 macrophage polarization. CCL20 could become a biomarker for prediction of prognosis in PCa patients. Intervention of SCFAs-producing microbiotas may be a useful strategy in manipulation of CRPC.

ETV7 reduces inflammatory responses in breast cancer cells by repressing the TNFR1/NF-κB axis

The transcription factor ETV7 is an oncoprotein that is up-regulated in all breast cancer (BC) types. We have recently demonstrated that ETV7 promoted breast cancer progression by increasing cancer cell proliferation and stemness and was also involved in the development of chemo- and radio-resistance. However, the roles of ETV7 in breast cancer inflammation have yet to be studied. Gene ontology analysis previously performed on BC cells stably over-expressing ETV7 demonstrated that ETV7 was involved in the suppression of innate immune and inflammatory responses. To better decipher the involvement of ETV7 in these signaling pathways, in this study, we identified TNFRSF1A, encoding for the main receptor of TNF-α, TNFR1, as one of the genes down-regulated by ETV7. We demonstrated that ETV7 directly binds to the intron I of this gene, and we showed that the ETV7-mediated down-regulation of TNFRSF1A reduced the activation of NF-κB signaling. Furthermore, in this study, we unveiled a potential crosstalk between ETV7 and STAT3, another master regulator of inflammation. While it is known that STAT3 directly up-regulates the expression of TNFRSF1A, here we demonstrated that ETV7 reduces the ability of STAT3 to bind to the TNFRSF1A gene via a competitive mechanism, recruiting repressive chromatin remodelers, which results in the repression of its transcription. The inverse correlation between ETV7 and TNFRSF1A was confirmed also in different cohorts of BC patients. These results suggest that ETV7 can reduce the inflammatory responses in breast cancer through the down-regulation of TNFRSF1A.

The role of toll-like receptors (TLRs) and their therapeutic applications in endometrial cancer

Endometrial cancer (EC) is developed nations' most prevalent form of gynecologic cancer. Patients are frequently diagnosed with EC when the tumor is still limited to the uterus. Patients without tumor metastasis have a 5-year survival rate ranging from 80 to 90%; however, almost 16.8% of EC patients develop a metastatic form of the tumor. In the early stages of tumorigenesis, the immune system is able to identify aberrant cells as non-self, therefore providing the optimal pro-inflammatory microenvironment for the elimination of cancer cells. Although, chronic inflammation can be a crucial aspect of tumor development. Toll-like receptors (TLRs), as the main pattern recognition receptors (PRRs) in innate immunity, may stimulate an inflammatory response and provide cell survival in the tumor microenvironment (TME). TLRs are vital immunomodulators that may significantly impact the development of gynecologic malignancies. Therefore, TLR inhibitors are being researched for their possible benefits in treating gynecologic cancers. The aim of this study is to review the current knowledge in this field and provide some insight into the therapeutic potential of TLR inhibitors in EC.

Could Toll-like Receptor 2 Serve as Biomarker to Detect Advanced Gastric Cancer?

Gastric cancer is one of the five most common types of cancer worldwide. Due to the heterogeneous course and the involvement of many risk factors, its treatment and diagnosis is an important challenge for modern medicine. Recent studies have emphasized the i role of Toll-like receptors (TLRs) expressed on selected cells of the immune system in the pathogenesis of gastric cancer. The aim of this study was to determine the prevalence of TLR2 on T lymphocytes, B lymphocytes, monocytes, and dendritic cells in patients diagnosed with gastric cancer, with particular emphasis on the stage of the disease. Based on the obtained results, we have shown that patients with gastric cancer are characterized by a higher percentage of all tested populations of peripheral blood immune cells expressing TLR2 in relation to patients from the control group. Moreover, a detailed analysis of the collected results showed a significant link between TLR2 and the stage of the disease.

Cytosolic DNA sensors and glial responses to endogenous DNA

Genomic instability is a key driving force for the development and progression of many neurodegenerative diseases and central nervous system (CNS) cancers. The initiation of DNA damage responses is a critical step in maintaining genomic integrity and preventing such diseases. However, the absence of these responses or their inability to repair genomic or mitochondrial DNA damage resulting from insults, including ionizing radiation or oxidative stress, can lead to an accumulation of self-DNA in the cytoplasm. Resident CNS cells, such as astrocytes and microglia, are known to produce critical immune mediators following CNS infection due to the recognition of pathogen and damage-associated molecular patterns by specialized pattern recognition receptors (PRRs). Recently, multiple intracellular PRRs, including cyclic GMP-AMP synthase, interferon gamma-inducible 16, absent in melanoma 2, and Z-DNA binding protein, have been identified as cytosolic DNA sensors and to play critical roles in glial immune responses to infectious agents. Intriguingly, these nucleic acid sensors have recently been shown to recognize endogenous DNA and trigger immune responses in peripheral cell types. In the present review, we discuss the available evidence that cytosolic DNA sensors are expressed by resident CNS cells and can mediate their responses to the presence of self-DNA. Furthermore, we discuss the potential for glial DNA sensor-mediated responses to provide protection against tumorigenesis versus the initiation of potentially detrimental neuroinflammation that could initiate or foster the development of neurodegenerative disorders. Determining the mechanisms that underlie the detection of cytosolic DNA by glia and the relative role of each pathway in the context of specific CNS disorders and their stages may prove pivotal in our understanding of the pathogenesis of such conditions and might be leveraged to develop new treatment modalities.

Early activation of Toll-like receptor-3 reduces the pathological progression of Alzheimer's disease in APP/PS1 mouse

BACKGROUND

Toll-like receptor 3 (TLR3) plays an important role in the immune/inflammatory response in the nervous system and is a main pathological feature of Alzheimer's disease (AD). This study investigates the role of early activation of TLR3 in the pathophysiological process of AD.

METHODS

In the experiment, the agonist of TLR3, Poly(I:C), was intraperitoneally injected into the APP/PS1 mouse model of AD and wild-type control mice starting from the age of 4 to 9 months. At the age of 14 months, behavioral tests were conducted. Western blot and immunohistochemistry staining were used to evaluate the level of amyloid β-protein (Aβ), the activation of inflammatory cells, and neuron loss. In addition, the levels of inflammatory cytokines were measured using a quantitative polymerase chain reaction.

RESULTS

The results demonstrated that the early activation of TLR3 attenuated neuronal loss and neurobehavioral dysfunction. Moreover, the early activation of TLR3 reduced Aβ deposition, inhibited the activation of microglia and astrocytes, and decreased the transcription of pro-inflammatory factors in the hippocampus.

CONCLUSIONS

The results indicated that the activation of TLR3 by Poly (I:C) in the early stage of development of AD in a mouse model attenuated neuron loss and improved neurobehavioral functions. The underlying mechanisms could be attributed to its role in Aβ clearance, the inhibition of glial cells, and the regulation of neuroinflammation in the hippocampus.

Caveolin-1 regulates OMV-induced macrophage pro-inflammatory activation and multiple Toll-like receptors

Macrophages (MФ), the primary cell of the innate immune system, serves as the first line of defense. During bacterial infection, Gram-negative (G-) bacteria release nanosized outer membrane vesicles (OMVs), facilitating the crosstalk between the microbe and the host. The underlying mechanisms by which OMVs induced pro-inflammatory (M1) activation are still unknown. Our study shows that OMVs caused M1 activation via modulating various toll-like receptor (TLR) expressions as they contain LPS, LTA, bacterial DNAs, and flagellins. Also, we found that caveolin-1 (cav-1), a 21-kDa scaffolding protein of caveolae and lipid rafts, plays a significant role in OMV-induced pro-inflammatory response in regulating various TLR signaling pathways. Specifically, cav-1 deletion increased the expression of OMV-induced TLRs, pro-inflammatory cytokine secretions (TNF-α and IL-1β), and the reactive oxygen species (ROS) production in MФs. Further, we examined the interaction between Cav-1 and TLR4 by immunoprecipitation, colocalization, and computational models, providing future direction to explore the role of cav-1 in OMV-induced other TLR signaling. Altogether, Cav-1 is a key regulator in OMV-induced multiple TLRs response. This study promotes future research to develop drugs by targeting the specific motif of cav-1 or TLRs against bacterial infection and macrophage-mediated inflammation.

Toll-like Receptors and Celiac Disease

Celiac disease (CD) is an immune-mediated disorder triggered by dietary gluten intake in some genetically predisposed individuals; however, the additional non-HLA-related genetic factors implicated in CD immunopathogenesis are not well-defined. The role of the innate immune system in autoimmunity has emerged in the last few years. Genetic polymorphisms of some pattern-recognition receptors, including toll-like receptors (TLRs), have been associated with several autoimmune disorders. In this review, we summarize and discuss the evidence from basic research and clinical studies as regards the potential role of TLRs in CD immunopathogenesis. The evidence supporting the role of TLRs in CD immunopathogenesis is limited, especially in terms of basic research. However, differences in the expression and activation of TLRs between active CD patients from one side, and controls and treated CD patients from the other side, have been described in some clinical studies. Therefore, TLRs may be part of those non-HLA-related genetic factors implicated in CD etiopathogenesis, considering their potential role in the interaction between the host immune system and some environmental factors (including viral infections and gut microbiota), which are included in the list of candidate agents potentially contributing to the determination of CD risk in genetically predisposed individuals exposed to dietary gluten intake. Further basic research and clinical studies focused on TLRs in the context of CD and other gluten-related disorders are needed.

Pathogenesis of (smoking-related) non-communicable diseases-Evidence for a common underlying pathophysiological pattern

Non-communicable diseases, like diabetes, cardiovascular diseases, cancer, stroke, chronic obstructive pulmonary disease, osteoporosis, arthritis, Alzheimer's disease and other more are a leading cause of death in almost all countries. Lifestyle factors, especially poor diet and tobacco consumption, are considered to be the most important influencing factors in the development of these diseases. The Western diet has been shown to cause a significant distortion of normal physiology, characterized by dysregulation of the sympathetic nervous system, renin-angiotensin aldosterone system, and immune system, as well as disruption of physiological insulin and oxidant/antioxidant homeostasis, all of which play critical roles in the development of these diseases. This paper addresses the question of whether the development of smoking-related non-communicable diseases follows the same pathophysiological pattern. The evidence presented shows that exposure to cigarette smoke and/or nicotine causes the same complex dysregulation of physiology as described above, it further shows that the factors involved are strongly interrelated, and that all of these factors play a key role in the development of a broad spectrum of smoking-related diseases. Since not all smokers develop one or more of these diseases, it is proposed that this disruption of normal physiological balance represents a kind of pathogenetic "basic toolkit" for the potential development of a range of non-communicable diseases, and that the decision of whether and what disease will develop in an individual is determined by other, individual factors ("determinants"), such as the genome, epigenome, exposome, microbiome, and others. The common pathophysiological pattern underlying these diseases may provide an explanation for the often poorly understood links between non-communicable diseases and disease comorbidities. The proposed pathophysiological process offers new insights into the development of non-communicable diseases and may influence the direction of future research in both prevention and therapy.

Breast Cancer Vaccine Containing a Novel Toll-like Receptor 7 Agonist and an Aluminum Adjuvant Exerts Antitumor Effects

Mucin 1 (MUC1) has received increasing attention due to its high expression in breast cancer, in which MUC1 acts as a cancer antigen. Our group has been committed to the development of small-molecule TLR7 (Toll-like receptor 7) agonists, which have been widely investigated in the field of tumor immunotherapy. In the present study, we constructed a novel tumor vaccine (SZU251 + MUC1 + Al) containing MUC1 and two types of adjuvants: a TLR7 agonist (SZU251) and an aluminum adjuvant (Al). Immunostimulatory responses were first verified in vitro, where the vaccine promoted the release of cytokines and the expression of costimulatory molecules in mouse BMDCs (bone marrow dendritic cells) and spleen lymphocytes. Then, we demonstrated that SZU251 + MUC1 + Al was effective and safe against a tumor expressing the MUC1 antigen in both prophylactic and therapeutic schedules in vivo. The immune responses in vivo were attributed to the increase in specific humoral and cellular immunity, including antibody titers, CD4⁺, CD8⁺ and activated CD8⁺ T cells. Therefore, our vaccine candidate may have beneficial effects in the prevention and treatment of breast cancer patients.

Characterization of immunomodulatory responses induced by manuka honey

Manuka honey (MH) is known for its wound-healing, anti-microbial, anti-oxidant and anti-tumor properties. However, there is conflicting evidence regarding the role of MH in inflammatory responses, with some studies highlighting its pro-inflammatory capacity and others showing that it has a predominantly anti-inflammatory activity. The current study is aimed at characterizing the immunomodulatory capacity of MH using both in vitro and in vivo approaches, focusing on the underlying mechanisms. Treatment of RAW 264.7 macrophages with 1% MH (w/v) resulted in a significant increase in the gene expression (~26-fold) and secretion (~27-fold) of tumor necrosis factor-alpha (TNF-α). Similarly, an increase was observed in the gene expression of other inflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6), and inducible nitric oxide synthase (iNOS), as well as the chemokines; (C-X-C motif) ligand 2 (CXCL2) and (C-C) motif ligand 2 (CCL2). Using an in vivo model, intraperitoneal (i.p.) administration of MH in C57BL/6 mice elicited a peritoneal response characterized by a significant expansion in the number of peritoneal exudate cells (PECs), which was mainly due to a 35-fold increase in the recruitment of neutrophils. Importantly, this response was evident in toll-like receptor 4 (TLR4)-defective C3H/HeJ mice, indicating that the observed stimulatory effect occurs independently of TLR4 and unlikely to be mediated by any lipopolysaccharide (LPS) contaminant. MH administration also led to changes in the phenotypic expression and functional maturation of peritoneal macrophages, as evidenced by a shift towards the CD11blo F4/80lo phenotype and an increase in the expression of major histocompatibility complex (MHC) class II proteins. In contrast, the MH-initiated peritoneal response was largely abrogated in mice deficient in myeloid differentiation primary response 88 (MyD88) protein, a critical adaptor of most TLR signaling pathways. Thus, the current findings help to characterize the immunostimulatory properties of MH and their dependence on TLR signaling, and highlight the potential utility of MH as an immunomodulatory agent in a variety of disorders.

Understanding the role of Toll-like receptors in lung cancer immunity and immunotherapy

Lung cancer is currently the leading cause of cancer-related deaths worldwide. Significant improvements in lung cancer therapeutics have relied on a better understanding of lung cancer immunity and the development of novel immunotherapies, as best exemplified by the introduction of PD-1/PD-L1-based therapies. However, this improvement is limited to lung cancer patients who respond to anti-PD-1 immunotherapy. Further improvements in immunotherapy may benefit from a better understanding of innate immune response mechanisms in the lung. Toll-like receptors (TLRs) are a key component of the innate immune response and mediate the early recognition of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). TLR signaling modulates the tumor microenvironment from "cold" to "hot" leading to immune sensitization of tumor cells to treatments and improved patient prognosis. In addition, TLR signaling activates the adaptive immune response to improve the response to cancer immunotherapy through the regulation of anti-tumor T cell activity. This review will highlight recent progress in our understanding of the role of TLRs in lung cancer immunity and immunotherapy.

Gut Microbiome in Inflammatory Bowel Disease: Role in Pathogenesis, Dietary Modulation, and Colitis-Associated Colon Cancer

The gut microbiome has increasingly been recognized as a critical and central factor in inflammatory bowel disease (IBD). Here, we review specific microorganisms that have been suggested to play a role in the pathogenesis of IBD and the current state of fecal microbial transplants as a therapeutic strategy in IBD. We discuss specific nutritional and dietary interventions in IBD and their effects on gut microbiota composition. Finally, we examine the role and mechanisms of the gut microbiome in mediating colitis-associated colon cancer.

Ultrasound improved immune adjuvant delivery to induce DC maturation and T cell activation

Tumor immunotherapy has emerged as a promising approach to tumor treatment. Currently, immune adjuvant-based therapeutic modalities are rarely curative in solid tumors owing to challenges including the low permeability and extremely poor water solubility of these adjuvants, limiting their ability to effectively promote dendritic cell (DC) maturation. Herein, we employed ultrasound-mediated cavitation (UMC) to promote the delivery of Toll-like receptor agonist (R837)-loaded pH-responsive liposomes (PEOz-Lip@R837) to tumors. The tumor-associated antigens (TAAs) produced by UMC treatment exhibited vaccinal activity, particularly in the presence of immune adjuvants, together promoting the maturation of DC and inducing cytokine production. Importantly, UMC can down-regulate immune checkpoint molecules, like Cd274, Foxp3 and Ctla4, synergistically stimulating the activation and proliferation of T cells in the body to facilitate tumor treatment. This UMC-enhanced PEOz-Lip@R837 approach was able to induce a robust antitumor immune response capable of arresting primary and distant tumor growth, while also developing immunological memory, protecting against tumor rechallenge following initial tumor clearance. Overall, these results highlight a promising UMC- and pH-sensitive immune adjuvant delivery-based treatment for tumors with the potential for clinical application.

Opioids and cancer survival: are we looking in the wrong place?

There is a controversial narrative in the anaesthetic literature suggesting that anaesthetic technique (including opioids) may be detrimental to survival after tumour resection. The initial observations were retrospective. Several prospective studies are ongoing; one in breast cancer has reported no adverse outcome. The evidence for an effect of opioids stems from three pieces of information: (1) opioids depress the immune system, (2) opioids potentially promote angiogenesis, and (3) opioids potentially support tumour growth. Although the evidence for (2)/(3) is unclear, combinations of these effects are beneficial to tumours and potentially promote metastatic reseeding. Accepted wisdom suggests that opioid effects are driven by opioid receptor activation but the presence of opioid receptors on immune cells for example is unlikely. Immune cells, vascular endothelium and a range of tumour cells express Toll-like receptor 4 (TLR4) receptors (for Gram-negative bacterial wall components), and there is growing evidence for opioids interacting with this alternative receptor; and for some there is paradoxical naloxone sensitivity. Is the focus on opioid receptors and cancer the wrong target? TLR4 receptor activation produces immune activation, stimulates angiogenesis, and supports tumour survival. We know that some opioids are more immune suppressive than others (there is no such comparative information for angiogenesis and tumour survival); this may correlate with TLR4 activation. If there are clusters of opioids that have more opioid than TLR4 profiles and vice versa, this may influence outcome. If this is the case, then evidence-based advice could be given for perioperative use in the oncology-anaesthesia setting.

Phytochemicals targeting Toll-like receptors 4 (TLR4) in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a collective term for inflammatory diseases including Crohn's disease and ulcerative colitis. Toll-like receptor 4 (TLR4) is thought to play a key role in the pathogenesis of IBD. Inhibition of TLR4 has been recognized as an effective target for the treatment of IBD. Many phytochemicals have been shown to have potential as new drugs for the treatment of IBD. This review surveyed the available literature and reports which focused on the in vivo effects of phytochemicals targeting TLR4 in different models of IBD, and clarified the significance of TLR4 as a current therapeutic target for IBD. Based on our review, we have concluded that phytochemicals targeting TLR4 are potentially effective candidates for developing new therapeutic drugs against IBD.

The role of the inflammasome and its related pathways in ovarian cancer

Ovarian cancer (OC) is the most lethal tumor of the female reproductive tract and one of the most prevalent causes of death among female cancer patients. The absence of suitable procedures for early diagnosis, chemoresistance, and limited surgical debulking are all contributing to poor survival in patients. Despite aggressive treatments, the majority of patients have a recurrence within 16-22 months. Inflammasomes are multimeric protein complexes that play a major role in the innate immune system and inflammation. The overexpression of inflammasome-related pathways, including NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3), Absent in melanoma 2 (AIM2), caspase-1, and Interleukin (IL)-1 have been reported in OC patients and in vitro cell lines. Therefore, inflammasome-related genes and protein might have a role in OC pathogenesis. Considering the potential relationship between inflammasome and OC, this study aimed to provide a literature-based review to explain the role of inflammasome and inflammation in cancer progression in OC.

Novel Wound Dressing Based on Postbiotic/Chitosan Film Accelerates Cutaneous Wound Healing

Background: Wound healing is a complex and overlapping process involving immune cells, cytokines, and growth factors. Objectives: This study aimed to design and evaluate a novel wound dressing based on postbiotic/chitosan in accelerating wound healing. Methods: Lactobacillus reuteri PTCC1655 was cultured, and the cell-free supernatant (postbiotic) was obtained by medium centrifugation. The films were prepared using the solvent casting method and evaluated in terms of water absorption index, water vapor transmission rate, and antimicrobial properties. Forty-five male Wistar rats were subjected to a full-thickness excisional wound to assess the wound healing potential. The rats were randomly divided into ctrl-, chitosan, and postbiotic groups. The time-course histological and gene expression analysis was performed to compare the dressing efficacy. Results: The films showed proper water absorption and water vapor transmission rate and inhibited the pathogens commonly associated with wound infection. The postbiotic film improved wound healing by modulating the inflammatory phase, increasing collagen and elastin deposition, and enhancing angiogenesis based on the histological results. The gene expression assay showed that the postbiotic film accelerated wound healing by improving the expression of inflammatory mediators (IL-6 and TNF-α) and anti-inflammatory mediators (TGF-β and VEGF). Conclusions: The cell-free supernatant/chitosan/polyethylene glycol (CFS/CS/PEG) biodegradable film could be introduced as a novel dressing for cutaneous wound healing. This transparent film enhances cutaneous wound healing by modulating infiltrated immunity cells and expressing inflammatory/anti-inflammatory cytokines.

The Anti-Apoptotic Role of COX-2 during In Vitro Infection of Human Intestinal Cell Line by Giardia duodenalis and The Potential Regulators

The protozoan parasite Giardia duodenalis inhabits the upper small intestine of mammals including humans and causes a disease known as giardiasis, which can lead to diarrhea, abdominal cramps, and bloating. G. duodenalis was known as a causative factor of intestinal epithelial cell (IEC) apoptosis. Cyclooxygenase-2 (COX-2) has been identified as an influencing factor of pathogen infection by participating in immune response, while its role in host defense against Giardia infection is not clear. Here we initially observed the involvement of COX-2 in the regulation of Giardia-induced IEC apoptosis. Inhibition of COX-2 activity could promote Giardia-induced reduction of IEC viability, increase of reactive oxygen species (ROS) production, and decrease of nitric oxide (NO) release, which would exacerbate IEC apoptosis. In addition, during Giardia-IEC interactions, COX-2 inhibition was able to accelerate caspase-3 activation and PARP cleavage, and inhibit the expressions of some anti-apoptotic proteins like cIAP-2 and survivin. In contrast, COX-2 over-expression could reduce Giardia-induced IEC apoptosis. We further investigated the regulatory mechanisms affecting COX-2 expression in terms of anti-apoptosis. The results showed that p38/ERK/AKT/NF-κB signaling could regulate COX-2-mediated ROS/NO production and anti-IEC apoptosis during Giardia infection. We also found that COX-2-mediated anti-IEC apoptosis induced by Giardia was related to TLR4-dependent activation of p38-NF-κB signaling. Collectively, this study identified COX-2 as a promoter for apoptotic resistance during Giardia-IEC interactions and determined the potential regulators, furthering our knowledge of anti-Giardia host defense mechanism.

Understanding immune-modulatory efficacy in vitro

Boosting or suppressing our immune system represents an attractive adjunct in the treatment of infections including SARS-CoV-2, cancer, AIDS, malnutrition, age related problems and some inflammatory disorders. Thus, there has been a growing interest in exploring and developing novel drugs, natural or synthetic, that can manipulate our defence mechanism. Many of such studies, reported till date, have been designed to explore effect of the therapeutic on function of macrophages, being a key component in innate immune system. Indeed, RAW264.7, J774A.1, THP-1 and U937 cell lines act as ideal model systems for preliminary investigation and selection of dose for in vivo studies. Several bioassays have been standardized so far where many techniques require high throughput instruments, cost effective reagents and technical assistance that may hinder many scholars to perform a method demanding compilation of available protocols. In this review, we have taken an attempt for the first time to congregate commonly used in vitro immune-modulating techniques explaining their principles. The study detected that among about 40 different assays and more than 150 sets of primers, the methods of cell proliferation by MTT, phagocytosis by neutral red, NO detection by Griess reaction and estimation of expression of TLRs, COX-2, iNOS, TNF-α, IL-6 and IL-1β by PCR have been the most widely used to screen the therapeutics under investigation.

Conjugate of ibrutinib with a TLR7 agonist suppresses melanoma progression and enhances antitumor immunity

The use of large molecules for immunotherapy has led to exciting developments in cancer treatment, such as the development of PD-1/PD-L1 antibodies. However, small molecule targeted therapies still lack effective immune-functional classes. Ideal anticancer drugs should simultaneously generate immune memory when killing cancer cells to prevent tumor relapse and metastasis. To this end, we carried out a rationally designed strategy to develop novel classes of small molecule compounds with bifunctional targeting and immunostimulatory abilities by conjugating targeting compounds with TLR7 agonists, generating immune-targeting conjugates (ImmunTacs). GY161, as a representative ImmunTac, was synthesized via chemical conjugation of ibrutinib with a TLR7 agonist. In vitro, GY161 stimulated the production of cytokines by mouse spleen lymphocytes, promoted the maturation of dendritic cells (DCs), and inhibited the growth and induced the apoptosis of B16 melanoma cells by regulating the c-Met/β-catenin pathway. In vivo, GY161 enhanced the frequency of CD8⁺ T cells in spleens and tumors, suppressed the growth of B16 melanoma cell-derived tumors and prolonged the survival time of mice. In summary, GY161 could prevent melanoma progression through direct tumor killing and by triggering specific immunity. These results strongly suggest that ImmunTacs are a reliable and promising strategy for developing small molecule immunogenic anticancer drugs.

Toll-Like Receptors (TLRs) and their potential therapeutic applications in diabetic neuropathy

One of the most common diabetic microvascular complications is diabetic neuropathy (DN). Immune cell infiltration in the peripheral nerve system (PNS), myelin loss, Schwann cell death, and axonal damage are all hallmarks of DN, which is currently believed to be a chronic inflammatory disease. Toll-like receptors (TLRs) are found in various types of nervous system cells, including Schwann cells, microglia, oligodendrocytes, astrocytes, and neurons. Proinflammatory mediators released at the end of TLR signal transduction can trigger an inflammatory response involving the nervous system. Studies on the association between TLRs and DN began as early as 2004. Since then, several studies have been conducted to assess the involvement of TLRs in the pathogenesis of DN. The focus of this review is to give a complete summary of the researches that have been done in this context, as well as an overview of the role of TLRs and their therapeutic applications in DN.

Achyranthes bidentata Polysaccharide Activates Nuclear Factor-Kappa B and Promotes Cytokine Production in J774A.1 Cells Through TLR4/MyD88 Signaling Pathway

Achyranthes bidentata Blume, a traditional Chinese medicine, is widely acknowledged for its function of invigorating the liver and kidneys and as a stranguria-relieving diuretic and used in the treatment of edema, gonorrhea, and other diseases. Polysaccharide (ABPS), isolated from Achyranthes bidentata Blume, has been demonstrated to have multiple biological activities including immunomodulatory effects. However, the mechanisms underlying the effects of ABPS have not been fully investigated. The present study is conducted to explore the underlying mechanism of immunomodulatory activities of ABPS. Results showed that ABPS significantly increased the secretion of IL-1β and TNF-α in J744 A.1 cells. Nitric oxide (NO) also significantly increased after ABPS treatment. The special antibodies (Toll-like receptor 4 (TLR4) antibody and CD14/TLR4 antibody) significantly decreased the activation, while the Toll-like receptor 2 (TLR2) antibody could not abolish this activation. Meanwhile, pyrrolidine dithiocarbamate (PDTC), a specific inhibitor of NF-κB, remarkably inhibited the secretion of IL-1β and TNF-α induced by ABPS in J744 A.1 cells. Western blotting (WB) and confocal laser scanning microscopy (CLSM) showed that ABPS promoted NF-κB translocation into the nucleus. Furthermore, the mRNA and protein expression of TLR4 and MyD88 were significantly increased after ABPS treatment. Taken together, these findings suggested that the immunomodulatory mechanism of ABPS was associated with the secretion of cytokines by stimulating the NF-κB pathway through TLR4/MyD88 signaling.

Suppression of PTRF Alleviates Post-Infectious Irritable Bowel Syndrome via Downregulation of the TLR4 Pathway in Rats

Background: Accumulating evidence suggests that the polymerase I and transcript release factor (PTRF), a key component of the caveolae structure on the plasma membrane, plays a pivotal role in suppressing the progression of colorectal cancers. However, the role of PTRF in the development of functional gastrointestinal (GI) disorders remains unclear. Post-infectious irritable bowel syndrome (PI-IBS) is a common functional GI disorder that occurs after an acute GI infection. Here, we focused on the role of PTRF in the occurrence of PI-IBS and investigated the underlying mechanisms. Methods: Lipopolysaccharide (LPS) (5 μg/ml) was used to induce inflammatory injury in human primary colonic epithelial cells (HCoEpiCs). Furthermore, a rat model of PI-IBS was used to study the role of PTRF. Intestinal sensitivity was assessed based on the fecal water content. A two-bottle sucrose intake test was used to evaluate behavioral changes. Furthermore, shRNA-mediated knockdown of PTRF was performed both in vitro and in vivo. We detected the expression of PTRF in colonic mucosal tissues through immunohistochemistry (IHC), western blotting (WB), and immunofluorescence (IF) analysis. Luciferase activity was quantified using a luciferase assay. Co-localization of PTRF and Toll-like receptor 4 (TLR4) was detected using IF analysis. The activation of the signaling pathways downstream of TLR4, including the iNOs, p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) pathways, was detected via WB. The levels of NO, IL-1β, IL-6, and TNF-α were measured using enzyme-linked immunosorbent assays. Results: LPS significantly induced PTRF expression and signaling downstream of TLR4, including p38, ERK, and JNK pathways, in HCoEpiCs. Moreover, shRNA-mediated knockdown of PTRF in HCoEpiCs significantly decreased the phosphorylation of JNK, ERK, and p38 and iNOS expression. In PI-IBS rats, the lack of PTRF not only reduced fecal water content and suppressed depressive behavior but also increased the body weight. Furthermore, we found a strong co-localization pattern for PTRF and TLR4. Consistently, the lack of PTRF impaired TLR4 signaling, as shown by the decreased levels of p-JNK, p-ERK, and p-p38, which are upstream factors involved in iNOS expression. Conclusion: PTRF promoted PI-IBS and stimulated TLR4 signaling both in vitro and in vivo. The results of this study not only enlighten the pathogenesis of PI-IBS but also help us understand the biological activity of PTRF and provide an important basis for the clinical treatment of PI-IBS by targeting PTRF.

Probiotics and Trained Immunity

The characteristics of innate immunity have recently been investigated in depth in several research articles, and original findings suggest that innate immunity also has a memory capacity, which has been named “trained immunity”. This notion has revolutionized our knowledge of the innate immune response. Thus, stimulation of trained immunity represents a therapeutic alternative that is worth exploring. In this context, probiotics, live microorganisms which when administered in adequate amounts confer a health benefit on the host, represent attractive candidates for the stimulation of trained immunity; however, although numerous studies have documented the beneficial proprieties of these microorganisms, their mechanisms of action are not yet fully understood. In this review, we propose to explore the putative connection between probiotics and stimulation of trained immunity.

TLR4 signaling in the development of colitis-associated cancer and its possible interplay with microRNA-155

Ulcerative colitis (UC) has closely been associated with an increased risk of colorectal cancer. However, the exact mechanisms underlying colitis-associated cancer (CAC) development remain unclear. As a classic pattern-recognition receptor, Toll like receptor (TLR)4 is a canonical receptor for lipopolysaccharide of Gram-negative bacteria (including two CAC-associated pathogens Fusobacterium nucleatum and Salmonella), and functions as a key bridge molecule linking oncogenic infection to colonic inflammatory and malignant processes. Accumulating studies verified the overexpression of TLR4 in colitis and CAC, and the over-expressed TLR4 might promote colitis-associated tumorigenesis via facilitating cell proliferation, protecting malignant cells against apoptosis, accelerating invasion and metastasis, as well as contributing to the creation of tumor-favouring cellular microenvironment. In recent years, considerable attention has been focused on the regulation of TLR4 signaling in the context of colitis-associated tumorigenesis. MicroRNA (miR)-155 and TLR4 exhibited a similar dynamic expression change during CAC development and shared similar CAC-promoting properties. The available data demonstrated an interplay between TLR4 and miR-155 in the context of different disorders or cell lines. miR-155 could augment TLR4 signaling through targeting negative regulators SOCS1 and SHIP1; and TLR4 activation would induce miR-155 expression via transcriptional and post-transcriptional mechanisms. This possible TLR4-miR-155 positive feedback loop might result in the synergistic accelerating effect of TLR4 and miR-155 on CAC development.

Toll-Like Receptor Signaling in the Establishment and Function of the Immune System

Toll-like receptors (TLRs) are pattern recognition receptors that play a central role in the development and function of the immune system. TLR signaling promotes the earliest emergence of hematopoietic cells during development, and thereafter influences the fate and function of both primitive and effector immune cell types. Aberrant TLR signaling is associated with hematopoietic and immune system dysfunction, and both loss- and gain-of- function variants in TLR signaling-associated genes have been linked to specific infection susceptibilities and immune defects. Herein, we will review the role of TLR signaling in immune system development and the growing number of heritable defects in TLR signaling that lead to inborn errors of immunity.

Preclinical and clinical studies into the bioactivity of low-dose naltrexone (LDN) for oncotherapy

Naltrexone (NTX) is a nonspecific opioid antagonist that exerts pharmacological effects on the opioid axis by blocking opioid receptors distributed in cytoplastic and nuclear regions. NTX has been used in opioid use disorder (OUD), immune-associated diseases, alcoholism, obesity, and chronic pain for decades. However, low-dose naltrexone (LDN) also exhibits remarkable inhibition of DNA synthesis, viability, and other functions in numerous cancers and is involved in immune remodeling against tumor invasion and chemical toxicity. The potential anticancer activity of LDN is a focus of basic research. Herein, we summarize the associated studies on LDN oncotherapy to highlight the potential mechanisms and prospective clinical applications.

Digital Gene Expression Analysis of Epithelioid and Sarcomatoid Mesothelioma Reveals Differences in Immunogenicity

Malignant pleural mesothelioma (MPM) is an aggressive malignancy associated with asbestos exposure. Median survival ranges from 14 to 20 months after initial diagnosis. As of November 2020, the FDA approved a combination of immune checkpoint inhibitors after promising intermediate results. Nonetheless, responses remain unsatisfying. Adequate patient stratification to improve response rates is still lacking. This retrospective study analyzed formalin fixed paraffin embedded specimens from a cohort of 22 MPM. Twelve of those samples showed sarcomatoid, ten epithelioid differentiation. Complete follow-up, including radiological assessment of response by modRECIST and time to death, was available with reported deaths of all patients. RNA of all samples was isolated and subjected to digital gene expression pattern analysis. Our study revealed a notable difference between epithelioid and sarcomatoid mesothelioma, showing differential gene expression for 304/698 expressed genes. Whereas antigen processing and presentation to resident cytotoxic T cells as well as phagocytosis is highly affected in sarcomatoid mesothelioma, cell-cell interaction via cytokines seems to be of greater importance in epithelioid cases. Our work reveals the specific role of the immune system within the different histologic subtypes of MPM, providing a more detailed background of their immunogenic potential. This is of great interest regarding therapeutic strategies including immunotherapy in mesothelioma.