Toll-like receptor 4 regulates spontaneous intestinal tumorigenesis by up-regulating IL-6 and GM-CSF

Toll-like receptors in health and disease

Toll-like receptors (TLRs) are inflammatory triggers and belong to a family of pattern recognition receptors (PRRs) that are central to the regulation of host protective adaptive immune responses. Activation of TLRs in innate immune myeloid cells directs lymphocytes to produce the most appropriate effector responses to eliminate infection and maintain homeostasis of the body's internal environment. Inappropriate TLR stimulation can lead to the development of general autoimmune diseases as well as chronic and acute inflammation, and even cancer. Therefore, TLRs are expected to be targets for therapeutic treatment of inflammation-related diseases, autoimmune diseases, microbial infections, and human cancers. This review summarizes the recent discoveries in the molecular and structural biology of TLRs. The role of different TLR signaling pathways in inflammatory diseases, autoimmune diseases such as diabetes, cardiovascular diseases, respiratory diseases, digestive diseases, and even cancers (oral, gastric, breast, colorectal) is highlighted and summarizes new drugs and related clinical treatments in clinical trials, providing an overview of the potential and prospects of TLRs for the treatment of TLR-related diseases.

Harnessing innate immune pathways for therapeutic advancement in cancer

The innate immune pathway is receiving increasing attention in cancer therapy. This pathway is ubiquitous across various cell types, not only in innate immune cells but also in adaptive immune cells, tumor cells, and stromal cells. Agonists targeting the innate immune pathway have shown profound changes in the tumor microenvironment (TME) and improved tumor prognosis in preclinical studies. However, to date, the clinical success of drugs targeting the innate immune pathway remains limited. Interestingly, recent studies have shown that activation of the innate immune pathway can paradoxically promote tumor progression. The uncertainty surrounding the therapeutic effectiveness of targeted drugs for the innate immune pathway is a critical issue that needs immediate investigation. In this review, we observe that the role of the innate immune pathway demonstrates heterogeneity, linked to the tumor development stage, pathway status, and specific cell types. We propose that within the TME, the innate immune pathway exhibits multidimensional diversity. This diversity is fundamentally rooted in cellular heterogeneity and is manifested as a variety of signaling networks. The pro-tumor effect of innate immune pathway activation essentially reflects the suppression of classical pathways and the activation of potential pro-tumor alternative pathways. Refining our understanding of the tumor's innate immune pathway network and employing appropriate targeting strategies can enhance our ability to harness the anti-tumor potential of the innate immune pathway and ultimately bridge the gap from preclinical to clinical application.

Harnessing the innate immune system by revolutionizing macrophage-mediated cancer immunotherapy

Immunotherapy is a promising and safer alternative to conventional cancer therapies. It involves adaptive T-cell therapy, cancer vaccines, monoclonal antibodies, immune checkpoint blockade (ICB), and chimeric antigen receptor (CAR) based therapies. However, most of these modalities encounter restrictions in solid tumours owing to a dense, highly hypoxic and immune-suppressive microenvironment as well as the heterogeneity of tumour antigens. The elevated intra-tumoural pressure and mutational rates within fastgrowing solid tumours present challenges in efficient drug targeting and delivery. The tumour microenvironment is a dynamic niche infiltrated by a variety of immune cells, most of which are macrophages. Since they form a part of the innate immune system, targeting macrophages has become a plausible immunotherapeutic approach. In this review, we discuss several versatile approaches (both at pre-clinical and clinical stages) such as the direct killing of tumour-associated macrophages, reprogramming pro-tumour macrophages to anti-tumour phenotypes, inhibition of macrophage recruitment into the tumour microenvironment, novel CAR macrophages, and genetically engineered macrophages that have been devised thus far. These strategies comprise a strong and adaptable macrophage-toolkit in the ongoing fight against cancer and by understanding their significance, we may unlock the full potential of these immune cells in cancer therapy.

The functions and regulatory pathways of S100A8/A9 and its receptors in cancers

Inflammation primarily influences the initiation, progression, and deterioration of many human diseases, and immune cells are the principal forces that modulate the balance of inflammation by generating cytokines and chemokines to maintain physiological homeostasis or accelerate disease development. S100A8/A9, a heterodimer protein mainly generated by neutrophils, triggers many signal transduction pathways to mediate microtubule constitution and pathogen defense, as well as intricate procedures of cancer growth, metastasis, drug resistance, and prognosis. Its paired receptors, such as receptor for advanced glycation ends (RAGEs) and toll-like receptor 4 (TLR4), also have roles and effects within tumor cells, mainly involved with mitogen-activated protein kinases (MAPKs), NF-κB, phosphoinositide 3-kinase (PI3K)/Akt, mammalian target of rapamycin (mTOR) and protein kinase C (PKC) activation. In the clinical setting, S100A8/A9 and its receptors can be used complementarily as efficient biomarkers for cancer diagnosis and treatment. This review comprehensively summarizes the biological functions of S100A8/A9 and its various receptors in tumor cells, in order to provide new insights and strategies targeting S100A8/A9 to promote novel diagnostic and therapeutic methods in cancers.

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.

Inflammation suppresses DLG2 expression decreasing inflammasome formation

Purpose

Loss of expression of DLG2 has been identified in a number of cancers to contribute to the disease by resulting in increased tumor cell proliferation and poor survival. In light of the previous evidence that DLG2 alters the cell cycle and affects proliferation, combined with indications that DLG2 is involved in NLRP3 inflammasome axis we speculated that DLG2 has an immune function. So far, there is no data that clearly elucidates this role, and this study was designed to investigate DLG2 in inflammatory colon disease and in colon cancer as well as its impact on inflammasome induction.

Methods

The DLG2 expression levels were established in publicly available inflammation, colon cancer and mouse model datasets. The overexpression and silencing of DLG2 in colon cancer cells were used to determine the effect of DLG2 expression on the activation of the inflammasome and subsequent cytokine release.

Results

The expression of DLG2 is repressed in inflammatory colon diseases IBD and Ulcerative colitis as well as colorectal cancer tissue compared to healthy individuals. We subsequently show that induction with inflammatory agents in cell and animal models results in a biphasic alteration of DLG2 with an initial increase followed by an ensuing decrease. DLG2 overexpression leads to a significant increase in expression of IL1B, IκBζ and BAX, components that result in inflammasome formation. DLG2 silencing in THP1 cells resulted in increased release of IL-6 into the microenvironment which once used to treat bystander COLO205 cells resulted in an increase in STAT3 phosphorylation and an increase proliferating cells and more cells in the G2/M phase. Restoration of DLG2 to the colon resulted in reduced AKT and S6 signaling.

Conclusion

DLG2 expression is altered in response to inflammation in the gut as well as colon cancer, resulting in altered ability to form inflammasomes.

Trial registration

NCT03072641.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-022-04029-7.

The possible role of SRMS in colorectal cancer by bioinformatics analysis

BACKGROUND

Src-related kinase lacking C-terminal regulatory tyrosine and N-terminal myristoylation sites (SRMS) is a non-receptor tyrosine kinase that has been found to be overexpressed in various tumors. However, the role of SRMS in colorectal cancer (CRC) has not been well established.

METHODS

We evaluated the expression levels of SRMS in CRC using GEPIA, Oncomine, and HPA datasets. Survival information and gene expression data of CRC were obtained from The Cancer Genome Atlas (TCGA). Then, the association between SRMS and clinicopathological features was analyzed using UALCAN dataset. LinkedOmics was used to determine co-expression and functional networks associated with SRMS. Besides, we used TISIDB to assess the correlation between SRMS and immune signatures, including tumor-infiltrating immune cells and immunomodulators. Lastly, protein-protein interaction network (PPI) was established and the function enrichment analysis of the SRMS-associated immunomodulators and immune cell marker genes were performed using the STRING portal.

RESULTS

Compared to normal colorectal tissues, SRMS was found to be overexpressed in CRC tissues, which was correlated with a poor prognosis. In colon adenocarcinoma (COAD), the expression levels of SRMS are significantly correlated with pathological stages and nodal metastasis status. Functional network analysis suggested that SRMS regulates intermediate filament-based processes, protein autophosphorylation, translational initiation, and elongation signaling through pathways involving ribosomes, proteasomes, oxidative phosphorylation, and DNA replication. In addition, SRMS expression was correlated with infiltrating levels of CD4+ T cells, CD56dim, MEM B, Neutrophils, Th2, Th17, and Act DC. The gene ontology (GO) analysis of SRMS-associated immunomodulators and immune cell marker genes showed that they were mainly enriched in the immune microenvironment molecule-related signals. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of these genes indicated that they are involved in multiple cancer-related pathways.

CONCLUSIONS

SRMS is a promising prognostic biomarker and potential therapeutic target for CRC patients. In particular, SRMS regulates CRC progression by modulating cytokine-cytokine receptor interaction, chemokines, IL-17, and intestinal immune networks for IgA production signaling pathways among others. However, more studies are needed to validate these findings.

Anthocyanin Extract from Purple Sweet Potato Exacerbate Mitophagy to Ameliorate Pyroptosis in Klebsiella pneumoniae Infection

Given the rise of morbidity and mortality caused by Klebsiella pneumoniae (KP), the increasing number of strains resistant to antibiotics, and the emergence of hypervirulent Klebsiella pneumonia, treatment of KP infection becomes difficult; thus, novel drugs are necessary for treatment. Anthocyanins, or natural flavonoids, have an extensive effect against bacterial infection. However, few studies on anti-KP are identified. Here, we evaluated the therapeutic effect of purple sweet potato anthocyanins (PSPAs) on KP, containing 98.7% delphinidin 3-sambubioside. Results showed that KP-infected mice after PSPAs treatment manifested decreased mortality, weakened lung injury, dampened inflammatory responses, and reduced bacterial systemic dissemination in vivo. In Vitro, PSPAs significantly suppressed pyroptosis and restricted NLRP3 inflammasome activation in alveolar macrophages infected with KP. As for the mechanism, PSPAs promote mitophagy by recruiting Parkin to the mitochondria. PSPAs-conferred mitophagy increased mitochondrial membrane potential and decreased mitochondrial reactive oxygen species and mitochondrial DNA, resulting in impaired NLRP3 inflammasome activation. In addition, the promotion of mitophagy by PSPAs required the Nrf2 signaling pathway. Collectively, these findings suggest that PSPAs are a potential option for the treatment of KP infection.

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.

Short Time-Series Expression Transcriptome Data Reveal the Gene Expression Patterns of Dairy Cow Mammary Gland as Milk Yield Decreased Process

The existing research on dairy cow mammary gland genes is extensive, but there have been few reports about dynamic changes in dairy cow mammary gland genes as milk yield decrease. For the first time, transcriptome analysis based on short time-series expression miner (STEM) and histological observations were performed using the Holstein dairy cow mammary gland to explore gene expression patterns in this process of decrease (at peak, mid-, and late lactation). Histological observations suggested that the number of mammary acinous cells at peak/mid-lactation was significantly higher than that at mid-/late lactation, and the lipid droplets area secreted by dairy cows was almost unaltered across the three stages of lactation (p > 0.05). Totals of 882 and 1439 genes were differentially expressed at mid- and late lactation, respectively, compared to peak lactation. Function analysis showed that differentially expressed genes (DEGs) were mainly related to apoptosis and energy metabolism (fold change ≥ 2 or fold change ≤ 0.5, p-value ≤ 0.05). Transcriptome analysis based on STEM identified 16 profiles of differential gene expression patterns, including 5 significant profiles (false discovery rate, FDR ≤ 0.05). Function analysis revealed DEGs involved in milk fat synthesis were downregulated in Profile 0 and DEGs in Profile 12 associated with protein synthesis. These findings provide a foundation for future studies on the molecular mechanisms underlying mammary gland development in dairy cows.

Lactation Associated Genes Revealed in Holstein Dairy Cows by Weighted Gene Co-Expression Network Analysis (WGCNA)

Simple Summary

Weighted gene coexpression network analysis (WGCNA) is a novel approach that can quickly analyze the relationships between genes and traits. In the past few years, studies on the gene expression changes of dairy cow mammary glands were only based on transcriptome comparisons between two lactation stages. Few studies focused on the relationships between gene expression of the dairy mammary gland and lactation stage or milk composition in a lactation cycle. In this study, we detected milk yield and composition in a lactation cycle. For the first time, we constructed a gene coexpression network using WGCNA on the basis of 18 gene expression profiles during six stages of a lactation cycle by transcriptome sequencing, generating 10 specific modules. Genes in each module were performed with gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Module–trait relationship analysis showed a series of potential candidates related to milk yield and composition. The current study provides an important theoretical basis for the further molecular breeding of dairy cows.

Abstract

Weighted gene coexpression network analysis (WGCNA) is a novel approach that can quickly analyze the relationships between genes and traits. In this study, the milk yield, lactose, fat, and protein of Holstein dairy cows were detected in a lactation cycle. Meanwhile, a total of 18 gene expression profiles were detected using mammary glands from six lactation stages (day 7 to calving, −7 d; day 30 post-calving, 30 d; day 90 post-calving, 90 d; day 180 post-calving, 180 d; day 270 post-calving, 270 d; day 315 post-calving, 315 d). On the basis of the 18 profiles, WGCNA identified for the first time 10 significant modules that may be related to lactation stage, milk yield, and the main milk composition content. Genes in the 10 significant modules were examined with gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The results revealed that the galactose metabolism pathway was a potential candidate for milk yield and milk lactose synthesis. In −7 d, ion transportation was more frequent and cell proliferation related terms became active. In late lactation, the suppressor of cytokine signaling 3 (SOCS3) might play a role in apoptosis. The sphingolipid signaling pathway was a potential candidate for milk fat synthesis. Dairy cows at 315 d were in a period of cell proliferation. Another notable phenomenon was that nonlactating dairy cows had a more regular circadian rhythm after a cycle of lactation. The results provide an important theoretical basis for the further molecular breeding of dairy cows.

Biological characteristics of IL-6 and related intestinal diseases

The intestine serves as an important digestive and the largest immune organ in the body. Interleukin-6(IL-6), an important mediator of various pathways, participates in the interactions between different kinds of cells and closely correlates with intestinal physiological and pathological condition. In this review we summarize the signaling pathways of IL-6 and its functions in maintaining intestinal homeostasis. We also explored its relation with nervous system and highlight its potential role in Parkinson's disease. Based on its specialty of the double-side influences on intestinal tumors and inflammation, we summarize how they are done through distinctive process.

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

In the dark path of tumorigenesis, the more carefully the cancer biology is studied, the more brilliant answers could be given to the countless questions about its orchestrating derivers. The identification of the correlation between Toll-like receptors (TLRs) and different processes involved in carcinogenesis was one of the single points of blinding light highlighting the interconnection between the immune system and cancer. TLRs are a wide family of single-pass membrane-spanning receptors that have developed through the evolution to recognize the structurally conserved molecules derived from microorganisms or damaged cells. But this is not everything about these receptors as they could orchestrate several downstream signalling pathways leading to the formation or suppression of cancer cells. The present review is tempted to provide a concise schematic about the biology and the characters of TLRs and also summarize the major findings of the regulatory role of TLRs and their associated signalling in the pathogenesis of human cancers.

Identification and validation of an immune-related gene signature predictive of overall survival in colon cancer

The heterogeneity and complexity of tumor-immune microenvironments lead to diverse immunotherapy effects among colon cancer patients. It is crucial to identify immune microenvironment-related biomarkers and construct prognostic risk models. In this study, the immune and stromal scores of 415 cases from TCGA were calculated using the ESTIMATE algorithm. AXIN2, CCL22, CLEC10A, CRIP2, RUNX3, and TRPM5 were screened and established a prognostic immune-related gene (IRG) signature using by univariate, LASSO, and multivariate Cox regression models. The predicted performance of IRG signature was external validated by GSE39582 (n=519). Stratified survival analysis showed IRG signature was an effective predictor of survival in patients with different clinical characteristics. The protein expression level of six genes was validated by immunohistochemistry analysis. Difference analysis indicated the mutation rate, immune cell of resting NK cells and regulatory T cells infiltration and four immune checkpoints of PD-1, PD-L1, LAG3 and VSIR expression levels in the high-risk group were significantly higher than those in the low-risk group. A nomogram incorporating the gene signatures and clinical factors was demonstrated had a good accuracy (1-, 3-, and 5-year AUC= 0.799, 0.791, 0.738). Our study identified a novel IRG signature, which may provide some references for the clinical precision immunotherapy of patients.

The role of toll-like receptor 4 (TLR4) in cancer progression: A possible therapeutic target?

The toll-like receptor (TLR) family consists of vital receptors responsible for pattern recognition in innate immunity, making them the core proteins involved in pathogen detection and eliciting immune responses. The most studied member of this family, TLR4, has been the center of attention regarding its contributory role in many inflammatory diseases including sepsis shock and asthma. Notably, mounting pieces of evidence have proved that this receptor is aberrantly expressed on the tumor cells and the tumor microenvironment in a wide range of cancer types and it is highly associated with the initiation of tumorigenesis as well as tumor progression and drug resistance. Cancer therapy using TLR4 inhibitors has recently drawn scientists' attention, and the promising results of such studies may pave the way for more investigation in the foreseeable future. This review will introduce the key proteins of the TLR4 pathway and how they interact with major growth factors in the tumor microenvironment. Moreover, we will discuss the many aspects of tumor progression affected by the activation of this receptor and provide an overview of the recent therapeutic approaches using various TLR4 antagonists.

Development and validation of a five-immune gene prognostic risk model in colon cancer

BACKGROUND

Colon cancer is a common and highly malignant cancer. Its morbidity is rapidly increasing, and its prognosis is poor. Currently, immunotherapy is a rapidly developing therapeutic modality of colon cancer. This study aimed to construct a prognostic risk model based on immune genes for the early diagnosis and accurate prognostic prediction of colon cancer.

METHODS

Transcriptomic data and clinical data were downloaded from The Cancer Genome Atlas database. Immune genes were obtained from the ImmPort database. Differentially expressed (DE) immune genes between 473 colon cancer and 41 adjacent normal tissues were identified. The entire cohort was randomly divided into the training and testing cohort. The training cohort was used to construct the prognostic model. The testing and entire cohorts were used to validate the model. The clinical utility of the model and its correlation with immune cell infiltration were analyzed.

RESULTS

A total of 333 DE immune genes (176 up-regulated and 157 down-regulated) were detected. We developed and validated a five-immune gene model of colon cancer, including LBP, TFR2, UCN, UTS2, and MC1R. This model was approved to be an independent prognostic variable, which was more accurate than age and the pathological stage for predicting overall survival at five years. Besides, as the risk score increased, the content of CD8+ T cells in colon cancer was decreased.

CONCLUSIONS

We developed and validated a five-immune gene model of colon cancer, including LBP, TFR2, UCN, UTS2, and MC1R. This model could be used as an instrumental variable in the prognosis prediction of colon cancer.

Toll-like receptor 4 regulates spontaneous intestinal tumorigenesis by up-regulating IL-6 and GM-CSF

Inflammation is as an important component of intestinal tumorigenesis. The activation of Toll‐like receptor 4 (TLR4) signalling promotes inflammation in colitis of mice, but the role of TLR4 in intestinal tumorigenesis is not yet clear. About 80%–90% of colorectal tumours contain inactivating mutations in the adenomatous polyposis coli (Apc) tumour suppressor, and intestinal adenoma carcinogenesis in familial adenomatous polyposis (FAP) is also closely related to the germline mutations in Apc. The Apc^Min/+ (multiple intestinal neoplasia) model mouse is a well‐utilized model of FAP, an inherited form of intestinal cancer. In this study, Apc^Min/+ intestinal adenoma mice were generated on TLR4‐sufficient and TLR4‐deficient backgrounds to investigate the carcinogenic effect of TLR4 in mouse gut by comparing mice survival, peripheral blood cells, bone marrow haematopoietic precursor cells and numbers of polyps in the guts of Apc^Min/+ WT and Apc^Min/+ TLR4^−/− mice. The results revealed that TLR4 had a critical role in promoting spontaneous intestinal tumorigenesis. Significant differential genes were screened out by the high‐throughput RNA‐Seq method. After combining these results with KEGG enrichment data, it was determined that TLR4 might promote intestinal tumorigenesis by activating cytokine‐cytokine receptor interaction and pathways in cancer signalling pathways. After a series of validation experiments for the concerned genes, it was found that IL6, GM‐CSF (CSF2), IL11, CCL3, S100A8 and S100A9 were significantly decreased in gut tumours of Apc^Min/+ TLR4^−/− mice compared with Apc^Min/+ WT mice. In the functional study of core down‐regulation factors, it was found that IL6, GM‐CSF, IL11, CCL3 and S100A8/9 increased the viability of colon cancer cell lines and decreased the apoptosis rate of colon cancer cells with irradiation and chemical treatment.