Colorectal Cancer Immune Infiltrates: Significance in Patient Prognosis and Immunotherapeutic Efficacy

Lactobacillus intestinalis facilitates tumor-derived CCL5 to recruit dendritic cell and suppress colorectal tumorigenesis

Gut microbes play a crucial role in regulating the tumor microenvironment (TME) of colorectal cancer (CRC). Nevertheless, the deep mechanism between the microbiota-TME interaction has not been well explored. In this study, we for the first time discovered that Lactobacillus intestinalis (L. intestinalis) effectively suppressed tumor growth both in the AOM/DSS-induced CRC model and the ApcMin/+ spontaneous adenoma model. Our investigation revealed that L. intestinalis increased the infiltration of immune cells, particularly dendritic cells (DC), in the TME. Mechanically, the tumor-derived CCL5 induced by L. intestinalis recruited DC chemotaxis through the NOD1/NF-κB signaling pathway. In clinical samples and datasets, we found positive correlation between L. intestinalis, CCL5 level, and the DC-related genes. Our study provided a new strategy for microbial intervention for CRC and deepened the understanding of the interaction between tumor cells and the immune microenvironment modulated by gut microbes.

Exploring the Role of Cellular Interactions in the Colorectal Cancer Microenvironment

Colorectal cancer (CRC) stands as one of the tumors with globally high incidence and mortality rates. In recent years, researchers have extensively explored the role of the tumor immune microenvironment (TME) in CRC, highlighting the crucial influence of immune cell populations in driving tumor progression and shaping therapeutic outcomes. The TME encompasses an array of cellular and noncellular constituents, spanning tumor cells, immune cells, myeloid cells, and tumor-associated fibroblasts, among others. However, the cellular composition within the TME is highly dynamic, evolving throughout different stages of tumor progression. These shifts in cell subpopulation proportions lead to a gradual transition in the immune response, shifting from an early antitumor growth to a late-stage environment that supports tumor survival. Therefore, it is crucial to further investigate and understand the complex interactions among the various cell populations within the TME. In this review, we explore the key cellular components of varying origins, subpopulations with shared origins, and noncellular elements within the CRC TME, examining their interconnections and critical considerations for developing personalized and precise immunotherapy strategies.

Impact of HTLV-1 infection on clinicopathological characteristics and tumour immune microenvironment in colorectal cancer

Recent advances in anti-cancer therapy have indicated the significance of the tumour immune microenvironment in tumour progression and resistance to anti-cancer therapy. This study investigated primary colorectal cancer (CRC) tissues resected from 180 cases in a single institute in a region highly endemic for human T-cell leukaemia virus type 1 (HTLV-1) carriers. Among those 180 cases, 35 HTLV-1 carriers were identified. CRC patients who were HTLV-1 carriers were significantly older (mean age: 76.9 vs. 72.7 years, P = 0.0341), with a lower incidence of lymph node metastases (pN0: 91% vs. 65%, P = 0.0085), and lower tumour stages (stage III or IV: 11% vs. 36%, P = 0.0117) compared to non-carriers. HTLV-1 carriers tended to show a lower incidence of relapse, although the difference was not significant (P = 0.2272). The density of forkhead box P3-positive regulatory T cells (Tregs) was significantly higher in HTLV-1 carriers (median density: 132 vs. 89 cells/mm2, P = 0.0051). In situ hybridisation showed cells positive for HTLV-1 basic leucine zipper factor, likely representing lymphocytes located in stroma around the cancer nest. Our findings indicate that lymph node metastasis was significantly suppressed in CRC patients infected with HTLV-1. Since HTLV-1 infection reportedly impairs the immunosuppressive functions of Tregs, anti-cancer immune responses are potentially enhanced in CRC patients who are HTLV-1 carriers.

ITGB5 is a prognostic factor in colorectal cancer and promotes cancer progression and metastasis through the Wnt signaling pathway

Integrin beta5 (ITGB5) expression levels are dysregulated in a variety of cancers. However, the mechanism and clinical value of ITGB5 in colorectal cancer (CRC) remain unclear. The Gene Expression Omnibus (GEO) database, real-time PCR, Western blotting and immunohistochemistry were utilized to evaluate ITGB5 expression levels in CRC tissue. Clinical data from the GEO database were obtained to further explore the associations of ITGB5 with clinical features and patient survival. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and gene set enrichment analysis (GSEA) were performed to explore the functions and signaling pathways of ITGB5. In addition, ITGB5 expression was inhibited by siRNA, and the roles of ITGB5 in SW480 and RKO cell growth, migration and invasion, as well as in the Wnt/β-catenin signaling pathway, were investigated. Pancancer studies have shown that ITGB5 is highly expressed in a variety of cancers. Moreover, ITGB5 expression is significantly increased in CRC tissues and is correlated with TNM stage, invasion depth, lymph node metastasis and distant metastasis stage. Kaplan-Meier analysis and meta-analysis of the GSE39582 and GSE17538 datasets indicated that a high level of ITGB5 is a high risk factor for overall survival (OS) and disease-free survival (DFS). In addition, receiver operating characteristic (ROC) curve analysis revealed the value of ITGB5 in predicting DFS, and univariate and multivariate analyses showed that ITGB5 may be an independent prognostic factor for DFS. GO and KEGG analyses indicated that many GO terms related to the extracellular matrix (ECM), focal adhesion and ECM-receptor interaction pathways were enriched. GSEA revealed focal adhesion, cancer pathways, ECM-receptor interactions and Wnt signaling pathways in the samples with high ITGB5 expression. Correlation analysis revealed that high ITGB5 expression is significantly correlated with the TGF-β/EMT pathway and WNT targets. Silencing of ITGB5 inhibited SW480 and RKO cell proliferation, invasion and migration. Mechanistically, downregulated ITGB5 expression blocked the Wnt/β-catenin signaling pathway and epithelial-mesenchymal transition (EMT) in CRC cells. Moreover, ITGB5 expression was related to M0 macrophages, M2 macrophages, neutrophils and plasma cell fractions. ITGB5 may be associated with poor prognosis and metastasis in patients with CRC. ITGB5 may hold promise as a prognostic biomarker and a new potential therapeutic target for CRC.

The Immune Environment in Colorectal Adenoma: A Systematic Review

Background/Objectives: Research on colorectal adenoma is significantly less comprehensive compared to studies on colorectal carcinoma. Although colorectal adenoma is a precursor of the majority of sporadic colorectal cancers, not all adenomas develop into carcinomas. The complex interaction of immune responses in the premalignant tumor microenvironment might be a factor for that. Methods: In this systematic review, we aim to provide a thorough analysis of the current research examining the immune infiltration patterns in sporadic colorectal adenoma tissues in the context of immune cell-based, cytokine-based, and other immunological factor-related changes along the conventional adenoma-carcinoma sequence. The articles included in the review extend up to December 2024 in PubMed and Web of Science databases. Results: Most included studies have shown significant differences in immune cell counts, densities, and cytokine expression levels associated with premalignant colorectal lesions (and/or colorectal cancer). No consensus on the immune-related tendencies concerning CD4+T cells and CD8+T cells was reached. Decreasing expression of mDCs and plasma and naïve B cells were detected along the ACS. The increased density of tissue eosinophils in the adenoma tissue dramatically diminishes after the transition to carcinoma. As the adenoma progresses, the increasing expression of IL-1α, IL-4, IL-6, IL-8, IL-10, IL-17A, IL-21, IL-23, IL-33, and TGF-β and decreasing levels of IL-12A, IL-18, IFN-γ, and TNFα cytokines in the invasive carcinoma stage is being detected. The over-expression of COX-2, PD-1/PD-L1, CTLA-4, and ICOS/ICOSLG in the colorectal adenomatous and cancerous tissues was also observed. Conclusions: Further studies are needed for a better understanding of the whole picture of colorectal adenoma-associated immunity and its impact on precancerous lesion's potential to progress.

Causal relationship between immune cell signatures and colorectal cancer: a bi-directional, two-sample mendelian randomization study

BACKGROUND

Prior studies have demonstrated the association between immune cells and colorectal cancer (CRC). However, the causal link to specific immunophenotypes is limited. This study intends to elucidate the causal relationship of immune cell signatures on CRC.

METHODS

We performed a bi-directional and two-sample mendelian randomization (MR) study, utilizing GWAS summary data of 731 immune cell traits (n = 3,757) and CRC statistics (n = 470,002). The primary MR methodology was inverse-variance weighted (IVW) method. Furthermore, heterogeneity was evaluated by Cochran's Q test. MR-PRESSO and MR-Egger were employed to assess horizontal and vertical pleiotropy respectively. Sensitivity analysis and FDR correction were conducted in our results. These results were validated in both the UK Biobank and FinnGen cohorts. We also extracted transcriptomic data of CRC and adjacent non-tumor tissues from TCGA, and used CIBERSORT to compare the infiltration patterns of 22 immune cell panels between normal tissues and the tumor microenvironment (TME).

RESULTS

Our study indicated nine immune cell signatures had significant causality with the risk of CRC after sensitivity analysis and FDR correction. The positive results covered four panels: B cell, CD8 + T cell, Treg, and monocyte. IgD- CD38br and IgD + CD38br B cell, CD8dim and CD28 + CD45RA- CD8dim T cell, and CD14 on CD14 + CD16- monocyte were the protective factors of CRC. However, CD39 + resting Treg, CX3CR1 on CD14- CD16 + monocyte, FSC-A on HLA DR + T cell, and BAFF-R on B cell increased the risk of CRC. The results were validated in the UK Biobank data and FinnGen cohorts. The data from the TCGA database also confirmed the infiltration of B cell, CD8 + T cell, Treg, and monocyte panels in the TME.

CONCLUSION

This study highlights the causal link between specific immune cell phenotypes and CRC, providing valuable insights into the immune microenvironment's role in CRC. The validation of our findings using large-scale datasets (UK Biobank, FinnGen) and TCGA underscores the robustness of our results, offering new potential therapeutic targets for CRC treatment.

A comprehensive update on the potential of curcumin to enhance chemosensitivity in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers and a major cause of cancer-related mortality worldwide. The efficacy of chemotherapy agents in CRC treatment is often limited due to toxic side effects, heterogeneity of cancer cells, and the possibility of chemoresistance which promotes cancer cell survival through several mechanisms. Combining chemotherapy agents with natural compounds like curcumin, a polyphenol compound from the Curcuma longa plant, has been reported to overcome chemoresistance and increase the sensitivity of cancer cells to chemotherapeutics. Curcumin, alone or in combination with chemotherapy agents, has been demonstrated to prevent chemoresistance by modulating various signaling pathways, reducing the expression of drug resistance-related genes. The purpose of this article is to provide a comprehensive update on studies that have investigated the ability of curcumin to enhance the efficacy of chemotherapy agents used in CRC. It is hoped that it can serve as a template for future research on the efficacy of curcumin, or other natural compounds, combined with chemotherapy agents to maximize the effectiveness of therapy and reduce the side effects that occur in CRC or other cancers.

ZNF26-Associated Genes as Prognostic Signatures in Colorectal Cancer with Broad Therapeutic Implications

The identification of biomarkers correlated with colorectal cancer (CRC) prognosis holds substantial importance from both clinical and scientific perspectives. Zinc finger protein 26 (ZNF26) has not been previously investigated or documented in solid tumors; thus, further research is necessary to ascertain its prognostic value in CRC. Gene expression profiles and clinicopathological data were acquired from The Cancer Genome Atlas (TCGA) database. Subsequently, expression correlation was assessed utilizing the TCGA CRC cohort. The prognostic value of ZNF26 was evaluated through Kaplan-Meier (KM) and ROC curve analyses. Following this, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted to perform enrichment analysis between high- and low-ZNF26 expression groups. The association between immune cells, immune checkpoint genes, and ZNF26 expression levels was examined. Lastly, the research findings were further validated using CRC tissue samples. The results revealed that, in comparison to healthy controls, CRC significantly reduced ZNF26 expression. Elevated ZNF26 expression was associated with poorer overall survival in CRC patients. Additionally, high ZNF26 expression exhibited an inverse relationship with the immunological score and immune checkpoint gene expression in CRC patients. The findings from the TCGA data analysis were corroborated by the PCR results obtained from CRC tissue samples. ZNF26 is markedly upregulated in colorectal cancer tissues, potentially serving as a biomarker for CRC.

Uncovering NK cell sabotage in gut diseases via single cell transcriptomics

The identification of immune environments and cellular interactions in the colon microenvironment is essential for understanding the mechanisms of chronic inflammatory disease. Despite occurring in the same organ, there is a significant gap in understanding the pathophysiology of ulcerative colitis (UC) and colorectal cancer (CRC). Our study aims to address the distinct immunopathological response of UC and CRC. Using single-cell RNA sequencing datasets, we analyzed the profiles of immune cells in colorectal tissues obtained from healthy donors, UC patients, and CRC patients. The colon tissues from patients and healthy participants were visualized by immunostaining followed by laser confocal microscopy for select targets. Natural killer (NK) cells from UC patients on medication showed reduced cytotoxicity compared to those from healthy individuals. Nonetheless, a UC-specific pathway called the BAG6-NCR3 axis led to higher levels of inflammatory cytokines and increased the cytotoxicity of NCR3+ NK cells, thereby contributing to the persistence of colitis. In the context of colorectal cancer (CRC), both NK cells and CD8+ T cells exhibited significant changes in cytotoxicity and exhaustion. The GALECTIN-9 (LGALS9)-HAVCR2 axis was identified as one of the CRC-specific pathways. Within this pathway, NK cells solely communicated with myeloid cells under CRC conditions. HAVCR2+ NK cells from CRC patients suppressed NK cell-mediated cytotoxicity, indicating a reduction in immune surveillance. Overall, we elucidated the comprehensive UC and CRC immune microenvironments and NK cell-mediated immune responses. Our findings can aid in selecting therapeutic targets that increase the efficacy of immunotherapy.

Estrogen-related differences in antitumor immunity and gut microbiome contribute to sexual dimorphism of colorectal cancer

Colorectal cancer (CRC) is a multifaceted disease whose development and progression varies depending on tumor location, age of patients, infiltration of immune cells within cancer lesions, and the tumor microenvironment. These pathophysiological characteristics are additionally influenced by sex-related differences. The gut microbiome plays a role in initiation and progression of CRC, and shapes anti-tumor immune responses but how responsiveness of the immune system to the intestinal microbiota may contribute to sexual dimorphism of CRC is largely unknown. We studied survival, tumor-infiltrating immune cell populations and tumor-associated microbiome of a cohort of n = 184 male and female CRC patients through high-dimensional single-cell flow cytometry and 16S rRNA gene sequencing. We functionally tested the immune system-microbiome interactions in in-vivo and in-vitro models of the disease. High-dimensional single-cell flow cytometry showed that female patients are enriched by tumor-infiltrating invariant Natural Killer T (iNKT) cells but depleted by cytotoxic T lymphocytes. The enrichment of oral pathobionts and a reduction of β-glucuronidase activity are distinctive traits characterizing the gut microbiome of female patients affected by CRC. Functional assays using a collection of human primary iNKT cell lines demonstrated that the gut microbiota of female patients functionally impairs iNKT cell anti-tumor functions interfering with the granzyme-perforin cytotoxic pathway. Our results highlight a sex-dependent functional relationship between the gut microbiome, estrogen metabolism, and the decline of cytotoxic T cell responses, contributing to the sexual dimorphism observed in CRC patients with relevant implications for precision medicine and the design of targeted therapeutic approaches addressing sex bias in cancer.

Advancements in immunotherapy for colorectal cancer treatment: a comprehensive review of strategies, challenges, and future prospective

PURPOSE

Colorectal cancer (CRC) remains one of the leading causes of cancer-related mortality worldwide. Metastatic colorectal cancer (mCRC) continues to present significant challenges, particularly in patients with proficient mismatch repair/microsatellite stable (pMMR/MSS) tumors. This narrative review aims to provide recent developments in immunotherapy for CRC treatment, focusing on its efficacy and challenges.

METHODS

This review discussed the various immunotherapeutic strategies for CRC treatment, including immune checkpoint inhibitors (ICIs) targeting PD-1 and PD-L1, combination therapies involving ICIs with other modalities, chimeric antigen receptor T-cell (CAR-T) cell therapy, and cancer vaccines. The role of the tumor microenvironment and immune evasion mechanisms was also explored to understand their impact on the effectiveness of these therapies.

RESULTS

This review provides a comprehensive update of recent advancements in immunotherapy for CRC, highlighting the potential of various immunotherapeutic approaches, including immune checkpoint inhibitors, combination therapies, CAR-T therapy, and vaccination strategies. The results of checkpoint inhibitors, particularly in patients with MSI-H/dMMR tumors, which have significant improvements in survival rates have been observed. Furthermore, this review also addresses the challenges faced in treating pMMR/MSS CRC, which remains resistant to immunotherapy.

CONCLUSION

Immunotherapy plays a significant role in the treatment of CRC, particularly in patients with MSI-H/dMMR tumors. However, many challenges remain, especially in treating pMMR/MSS CRC. This review discussed the need for further research into combination therapies, biomarker development, CAR-T cell therapy, and a deeper understanding of immune evasion mechanisms for CRC treatment.

High levels of fibrotic tumor components are associated with recurrence and intratumoral immune status in advanced colorectal cancer patients

The importance of collagen and elastin remains incompletely understood concerning tumor immunity in cancer tissues. This study explored the clinical significance of collagen and elastin deposition on tumor immunity in advanced colorectal cancer patients. The collagen and elastin contents were assessed simultaneously using elastic van Gieson (EVG) histochemical staining. Immunohistochemical staining was performed to measure the immune cell markers CD3, CD8, CD86, and CD163 in surgically resected primary tumors from 78 pT4 colorectal cancer patients. High collagen, elastin, and EVG scores are associated with aggressive characteristics and short disease-free survival. A high EVG score was identified as an independent predictor of poor disease-free survival. Furthermore, tumors with high collagen and EVG scores exhibited significantly fewer intratumoral CD3 + and CD8 + cells. Evaluating tumor fibrosis using the classical and straightforward EVG staining method could be a reliable predictor of recurrence in high-risk colorectal cancer patients with tumor immune tolerance.

Development and validation of a preoperative systemic inflammation-based nomogram for predicting surgical site infection in patients with colorectal cancer

BACKGROUND

Surgical site infection (SSI) represents a significant postoperative complication in colorectal cancer (CRC). Identifying associated factors is therefore critical. We evaluated the predictive value of clinicopathological features and inflammation-based prognostic scores (IBPSs) for SSI occurrence in CRC patients.

METHODS

We retrospectively analyzed data from 1445 CRC patients who underwent resection surgery at Wuhan Union Hospital between January 2015 and December 2018. We applied two algorithms, least absolute shrinkage and selector operation (LASSO) and support vector machine-recursive feature elimination (SVM-RFE), to identify key predictors. Participants were randomly divided into training (n = 1043) and validation (n = 402) cohorts. A nomogram was constructed to estimate SSI risk, and its performance was assessed by calibration, discrimination, and clinical utility.

RESULTS

Combining the 30 clinicopathological features identified by LASSO and SVM-RFE, we pinpointed seven variables as optimal predictors for a pathology-based nomogram: obstruction, dNLR, ALB, HGB, ALT, CA199, and CA125. The model demonstrated strong calibration and discrimination, with an area under the curve (AUC) of 0.838 (95% CI 0.799-0.876) in the training cohort and 0.793 (95% CI 0.732-0.865) in the validation cohort. Decision curve analysis (DCA) showed that our models provided greater predictive benefit than individual clinical markers.

CONCLUSION

The model based on simplified clinicopathological features in combination with IBPSs is useful in predicting SSI for CRC patients.

Targeting cuproptosis with nano material: new way to enhancing the efficacy of immunotherapy in colorectal cancer

Colorectal cancer has emerged as one of the predominant malignant tumors globally. Immunotherapy, as a novel therapeutic methodology, has opened up new possibilities for colorectal cancer patients. However, its actual clinical efficacy requires further enhancement. Copper, as an exceptionally crucial trace element, can influence various signaling pathways, gene expression, and biological metabolic processes in cells, thus playing a critical role in the pathogenesis of colorectal cancer. Recent studies have revealed that cuproptosis, a novel mode of cell death, holds promise to become a potential target to overcome resistance to colorectal cancer immunotherapy. This shows substantial potential in the combination treatment of colorectal cancer. Conveying copper into tumor cells via a nano-drug delivery system to induce cuproptosis of colorectal cancer cells could offer a potential strategy for eliminating drug-resistant colorectal cancer cells and vastly improving the efficacy of immunotherapy while ultimately destroy colorectal tumors. Moreover, combining the cuproptosis induction strategy with other anti-tumor approaches such as photothermal therapy, photodynamic therapy, and chemodynamic therapy could further enhance its therapeutic effect. This review aims to illuminate the practical significance of cuproptosis and cuproptosis-inducing nano-drugs in colorectal cancer immunotherapy, and scrutinize the current challenges and limitations of this methodology, thereby providing innovative thoughts and references for the advancement of cuproptosis-based colorectal cancer immunotherapy strategies.

Adaptive Immune Receptor Distinctions Along the Colorectal Polyp-Tumor Timelapse

INTRODUCTION

Colorectal cancer (CRC) is the third-most common cancer diagnosed worldwide, with 1.85 million new cases per year. While mortality has significantly decreased due to preventive colonoscopy, only 5% of polyps identified progress to cancer. Studies have found that immunological alterations in other solid tumor microenvironments are associated with worse prognoses.

METHODS

We applied an immunogenomics approach to assess adaptive immune receptor gene expression changes that were associated with development of adenocarcinoma, utilizing 79 samples that represented normal, tubular, villous, and tumor colorectal tissue for 32 patients.

RESULTS

Results indicated that the number of productive TRD and TRG recombination reads, representing gamma-delta (γδ) T-cells, significantly decreased with progression from normal to tumor tissue. A further assessment of two independent CRC datasets was consistent with a decrease in TRD recombination reads with progression to CRC. Further, we identified three physicochemical parameters for immunoglobulin, complementarity determining region-3 (CDR3) amino acids associated with progression from normal to tumor tissue.

CONCLUSIONS

Overall, this study points towards a need for further investigation of γδ T-cells in relation to CRC development; and indicates immunoglobulin CDR3 physicochemical features as potential CRC biomarkers.

Cellular mechanisms of combining innate immunity activation with PD-1/PD-L1 blockade in treatment of colorectal cancer

PD-1/PD-L1 blockade therapies have displayed extraordinary clinical efficacy for melanoma, renal, bladder and lung cancer; however, only a minority of colorectal cancer (CRC) patients benefit from these treatments. The efficacy of PD-1/PD-L1 blockade in CRC is limited by the complexities of tumor microenvironment. PD-1/PD-L1 blockade immunotherapy is based on T cell-centered view of tumor immunity. However, the onset and maintenance of T cell responses and the development of long-lasting memory T cells depend on innate immune responses. Acknowledging the pivotal role of innate immunity in anti-tumor immune response, this review encapsulates the employment of combinational therapies those involve PD-1/PD-L1 blockade alongside the activation of innate immunity and explores the underlying cellular mechanisms, aiming to harnessing innate immune responses to induce long-lasting tumor control for CRC patients who received PD-1/PD-L1 blockade therapy.

ATG16L1 in myeloid cells limits colorectal tumor growth in ApcMin/+ mice infected with colibactin-producing Escherichia coli via decreasing inflammasome activation

Escherichia coli strains producing the genotoxin colibactin, designated as CoPEC (colibactin-producing E. coli), have emerged as an important player in the etiology of colorectal cancer (CRC). Here, we investigated the role of macroautophagy/autophagy in myeloid cells, an important component of the tumor microenvironment, in the tumorigenesis of a susceptible mouse model infected with CoPEC. For that, a preclinical mouse model of CRC, the ApcMin/+ mice, with Atg16l1 deficiency specifically in myeloid cells (ApcMin/+/Atg16l1[∆MC]) and the corresponding control mice (ApcMin/+), were infected with a clinical CoPEC strain 11G5 or its isogenic mutant 11G5∆clbQ that does not produce colibactin. We showed that myeloid cell-specific Atg16l1 deficiency led to an increase in the volume of colonic tumors in ApcMin/+ mice under infection with 11G5, but not with 11G5∆clbQ. This was accompanied by increased colonocyte proliferation, enhanced inflammasome activation and IL1B/IL-1β secretion, increased neutrophil number and decreased total T cell and cytotoxic CD8+ T cell numbers in the colonic mucosa and tumors. In bone marrow-derived macrophages (BMDMs), compared to uninfected and 11G5∆clbQ-infected conditions, 11G5 infection increased inflammasome activation and IL1B secretion, and this was further enhanced by autophagy deficiency. These data indicate that ATG16L1 in myeloid cells was necessary to inhibit colonic tumor growth in CoPEC-infected ApcMin/+ mice via inhibiting colibactin-induced inflammasome activation and modulating immune cell response in the tumor microenvironment. Abbreviation: AOM, azoxymethane; APC, APC regulator of WNT signaling pathway; ATG, autophagy related; Atg16l1[∆MC] mice, mice deficient for Atg16l1 specifically in myeloid cells; CASP1, caspase 1; BMDM, bone marrow-derived macrophage; CFU, colony-forming unit; CoPEC, colibactin-producing Escherichia coli; CRC, colorectal cancer; CXCL1/KC, C-X-C motif chemokine ligand 1; ELISA, enzyme-linked immunosorbent assay; IL, interleukin; MC, myeloid cell; MOI, multiplicity of infection; PBS, phosphate-buffered saline; pks, polyketide synthase; qRT-PCR, quantitative real-time reverse-transcription polymerase chain reaction; siRNA, small interfering RNA; TME, tumor microenvironment; TNF/TNF-α, tumor necrosis factor.

From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

Deciphering Regulatory T-Cell Dynamics in Cancer Immunotherapy: Mechanisms, Implications, and Therapeutic Innovations

This Review explores how tumor-associated regulatory cells (Tregs) affect cancer immunotherapy. It shows how Tregs play a role in keeping the immune system in check, how cancers grow, and how well immunotherapy work. Tregs use many ways to suppress the immune system, and these ways are affected by the tumor microenvironment (TME). New approaches to cancer therapy are showing promise, such as targeting Treg checkpoint receptors precisely and using Fc-engineered antibodies. It is important to tailor treatments to each patient's TME in order to provide personalized care. Understanding Treg biology is essential for creating effective cancer treatments and improving the long-term outcomes of immunotherapy.

Microbiota-associated mechanisms in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide, ranking third in terms of incidence and second as a cause of cancer-related death. There is growing scientific evidence that the gut microbiota plays a key role in the initiation and development of CRC. Specific bacterial species and complex microbial communities contribute directly to CRC pathogenesis by promoting the neoplastic transformation of intestinal epithelial cells or indirectly through their interaction with the host immune system. As a result, a protumoural and immunosuppressive environment is created conducive to CRC development. On the other hand, certain bacteria in the gut microbiota contribute to protection against CRC. In this chapter, we analysed the relationship of the gut microbiota to CRC and the associations identified with specific bacteria. Microbiota plays a key role in CRC through various mechanisms, such as increased intestinal permeability, inflammation and immune system dysregulation, biofilm formation, genotoxin production, virulence factors and oxidative stress. Exploring the interaction between gut microbiota and tumourigenesis is essential for developing innovative therapeutic approaches in the fight against CRC.

The role of innate immune cells in the colorectal cancer tumor microenvironment and advances in anti-tumor therapy research

Innate immune cells in the colorectal cancer microenvironment mainly include macrophages, neutrophils, natural killer cells, dendritic cells and bone marrow-derived suppressor cells. They play a pivotal role in tumor initiation and progression through the secretion of diverse cytokines, chemokines, and other factors that govern these processes. Colorectal cancer is a common malignancy of the gastrointestinal tract, and understanding the role of innate immune cells in the microenvironment of CRC may help to improve therapeutic approaches to CRC and increase the good prognosis. In this review, we comprehensively explore the pivotal role of innate immune cells in the initiation and progression of colorectal cancer (CRC), alongside an extensive evaluation of the current landscape of innate immune cell-based immunotherapies, thereby offering valuable insights for future research strategies and clinical trials.

Characterization of double-negative T cells in colorectal cancers and their corresponding lymph nodes

TCRαβ+ CD4- CD8- double-negative T (DNT) cells are minor populations in peripheral blood, and their roles have mostly been discussed in inflammation and autoimmunity. However, the functions of DNT cells in tumor microenvironment remain to be elucidated. We investigated their characteristics, possible origins and functions in colorectal cancer tissues as well as their corresponding tumor-draining lymph nodes. We found a significant enrichment of DNT cells in tumor tissues compared with their corresponding lymph nodes, especially in tumors with lower T cell infiltration. T cell receptor (TCR) sequence analysis of CD4+ T, CD8+ T and DNT cells indicated that TCR sequences detected in DNT cells were found in CD8+ T cells, but rarely in CD4+ T cells, suggesting that a part of DNT cells was likely to be originated from CD8+ T cells. Through a single-cell transcriptomic analysis of DNT cells, we found that a DNT cell cluster, which showed similar phenotypes to central memory CD8+ T cells with low expression of effector and exhaustion markers, revealed some specific gene expression patterns, including higher GZMK expression. Moreover, in flow cytometry analysis, we found that DNT cells lost production of cytotoxic mediators. These findings imply that DNT cells might function as negative regulators of anti-tumor immune responses in tumor microenvironment.

The tumor immune microenvironment and T-cell-related immunotherapies in colorectal cancer

The tumor microenvironment includes a complex network of immune T-cell subsets that play important roles in colorectal cancer (CRC) progression and are key elements of CRC immunotherapy. T cells develop and migrate within tumors, recognizing tumor-specific antigens to regulate immune surveillance. Current immunotherapies are divided into the following main categories based on the regulatory role of T-cell subsets in the tumor immune microenvironment (TIME): cytokines, monoclonal antibodies, peptide vaccines, CAR-T cells and more. This review describes the composition of the tumor immune microenvironment in colorectal cancer and the involvement of T cells in the pathogenesis and progression of CRC as well as current T-cell-related immunotherapies. Further studies on CRC-specific tumor antigens, the gene regulation of T cells, and the regulation of immune activity are needed.

Current and Future Trends of Colorectal Cancer Treatment: Exploring Advances in Immunotherapy

Cancer of the colon and rectum (CRC) has been identified among the three most prevalent types of cancer and cancer-related deaths for both sexes. Even though significant progress in surgical and chemotherapeutic techniques has markedly improved disease-free and overall survival rates in contrast to those three decades ago, recent years have seen a stagnation in these improvements. This underscores the need for new therapies aiming to augment patient outcomes. A number of emerging strategies, such as immune checkpoint inhibitors (ICIs) and adoptive cell therapy (ACT), have exhibited promising outcomes not only in preclinical but also in clinical settings. Additionally, a thorough appreciation of the underlying biology has expanded the scope of research into potential therapeutic interventions. For instance, the pivotal role of altered telomere length in early CRC carcinogenesis, leading to chromosomal instability and telomere dysfunction, presents a promising avenue for future treatments. Thus, this review explores the advancements in CRC immunotherapy and telomere-targeted therapies, examining potential synergies and how these novel treatment modalities intersect to potentially enhance each other's efficacy, paving the way for promising future therapeutic advancements.

Single-cell transcriptomics reveals stage- and side-specificity of gene modules in colorectal cancer

BACKGROUND

An understanding of mechanisms underlying colorectal cancer (CRC) development and progression is yet to be fully elucidated. This study aims to employ network theoretic approaches to analyse single cell transcriptomic data from CRC to better characterize its progression and sided-ness.

METHODS

We utilized a recently published single-cell RNA sequencing data (GEO-GSE178341) and parsed the cell X gene data by stage and side (right and left colon). Using Weighted Gene Co-expression Network Analysis (WGCNA), we identified gene modules with varying preservation levels (weak or strong) of network topology between early (pT1) and late stages (pT234), and between right and left colons. Spearman's rank correlation (ρ) was used to assess the similarity or dissimilarity in gene connectivity.

RESULTS

Equalizing cell counts across different stages, we detected 13 modules for the early stage, two of which were non-preserved in late stages. Both non-preserved modules displayed distinct gene connectivity patterns between the early and late stages, characterized by low ρ values. One module predominately dealt with myeloid cells, with genes mostly enriched for cytokine-cytokine receptor interaction potentiallystimulating myeloid cells to participate in angiogenesis. The second module, representing a subset of epithelial cells, was mainly enriched for carbohydrate digestion and absorption, influencing the gut microenvironment through the breakdown of carbohydrates. In the comparison of left vs. right colons, two of 12 modules identified in the right colon were non-preserved in the left colon. One captured a small fraction of epithelial cells and was enriched for transcriptional misregulation in cancer, potentially impacting communication between epithelial cells and the tumor microenvironment. The other predominantly contained B cells with a crucial role in maintaining human gastrointestinal health and was enriched for B-cell receptor signalling pathway.

CONCLUSIONS

We identified modules with topological and functional differences specific to cell types between the early and late stages, and between the right and left colons. This study enhances the understanding of roles played by different cell types at different stages and sides, providing valuable insights for future studies focused on the diagnosis and treatment of CRC.

Unlocking PD-1 antibody resistance: The MUC1 DNA vaccine augments CD8+ T cell infiltration and attenuates tumour suppression

In light of increasing resistance to PD1 antibody therapy among certain patient populations, there is a critical need for in-depth research. Our study assesses the synergistic effects of a MUC1 DNA vaccine and PD1 antibody for surmounting PD1 resistance, employing a murine CT26/MUC1 colon carcinoma model for this purpose. When given as a standalone treatment, PD1 antibodies showed no impact on tumour growth. Additionally, there was no change observed in the intra-tumoural T-cell ratios or in the functionality of T-cells. In contrast, the sole administration of a MUC1 DNA vaccine markedly boosted the cytotoxicity of CD8+ T cells by elevating IFN-γ and granzyme B production. Our compelling evidence highlights that combination therapy more effectively inhibited tumour growth and prolonged survival compared to either monotherapy, thus mitigating the limitations intrinsic to single-agent therapies. This enhanced efficacy was driven by a significant alteration in the tumour microenvironment, skewing it towards pro-immunogenic conditions. This assertion is backed by a raised CD8+/CD4+ T-cell ratio and a decrease in immunosuppressive MDSC and Treg cell populations. On the mechanistic front, the synergistic therapy amplified expression levels of CXCL13 in tumours, subsequently facilitating T-cell ingress into the tumour setting. In summary, our findings advocate for integrated therapy as a potent mechanism for surmounting PD1 antibody resistance, capitalizing on improved T-cell functionality and infiltration. This investigation affords critical perspectives on enhancing anti-tumour immunity through the application of innovative therapeutic strategies.

Interleukin-6-Positive Immune Cells as a Possible New Immunologic Marker Associated With the Colorectal Cancer Prognosis

Chronic inflammation creates tumor microenvironment (TME) that facilitates colorectal cancer (CRC) cell proliferation, migration, metastasis, and tumor progression. Interleukin-6 (IL-6) is a proinflammatory cytokine with a pleiotropic effect on CRC development. We aimed to evaluate IL-6 expression in tumor cells and in immune cells in TME, to assess the serum level and IL6 -174 G/C genotype distribution and to correlate the results with selected morphologic and clinical parameters that may add useful information in understanding the mechanisms of human CRC progression. A total of 153 patients with CRC were recruited in the current study. We assessed the IL-6 serum concentration through the ELISA method, the expression of IL-6 in tumor and in immune cells by immunohistochemical and double immunofluorescence staining, the MSI status by immunоhistochemistry for 4 mismatch repair (MMR) proteins, and the genotype distributions for IL6 -174G/C (rs1800795) single-nucleotide polymorphism through PCR-RFLP method. Our results showed that serum IL-6 level were increased in CRC patients as compared with healthy controls (P<0.0001), and in patients with cancers with advanced histologic type (type IV). However, the higher concentration (above the median of 55.71 pg/mL) was with borderline association with longer survival of the patients after surgical therapy (P=0.055, Log rank test). We also found that IL-6+ immune cells prevailed in the invasive front (IF) of tumors compared with the tumor stroma (TS) (P<0.0001). More IL-6+ cells were recruited in the tumors with less advanced histologic type (I+II), with stronger inflammatory infiltrate in the IF, in early pTNM stages (I+II), without lymph node and distant metastases and the higher levels of IL-6+ cells, especially in the IF, were associated with longer survival (P=0.012). The results of our study suggest that although the serum levels of IL-6 are higher in CRC, the increased IL-6+ cells in tumor microenvironment, both in the invasive front and in tumor stroma, as well as the higher serum levels are associated with good prognostic variables and longer survival of the patients mainly in the early stages of CRC.

Circulation immune cell landscape in canonical pathogenesis of colorectal adenocarcinoma by CyTOF analysis

Current studies on the immune microenvironment of colorectal cancer (CRC) were mostly limited to the tissue level, lacking relevant studies in the peripheral blood, and failed to describe its alterations in the whole process of adenocarcinoma formation, especially of adenoma carcinogenesis. Here, we constructed a large-scale population cohort and used the CyTOF to explore the changes of various immune cell subsets in peripheral blood of CRC. We found monocytes and basophils cells were significantly higher in adenocarcinoma patients. Compared with early-stage CRC, effector CD4+T cells and naive B cells were higher in patients with lymph node metastasis, whereas the basophils were lower. We also performed random forest algorithm and found monocytes play the key role in carcinogenesis. Our study draws a peripheral blood immune cell landscape of the occurrence and development of CRC at the single-cell level and provides a reference for other researchers.

The Mechanistic Target of Rapamycin Complex 1 Pathway Contributes to the Anti-Tumor Effect of Granulocyte-Macrophage-Colony-Stimulating Factor-Producing T Helper Cells in Mouse Colorectal Cancer

INTRODUCTION

The role of granulocyte-macrophage-colony-stimulating factor-producing T helper (ThGM) cells in colorectal cancer (CRC) development remains unclear. This study characterizes the function of ThGM cells in mouse CRC.

METHODS

Mouse CRC was induced by administrating azoxymethane and dextran sulfate sodium. The presence of ThGM cells in CRC tissues and the mechanistic target of rapamycin complex 1 (mTORC1) signaling in ThGM cells was detected by flow cytometry. The impact of mTORC1 signaling on ThGM cell function was determined by in vitro culture. The effect of ThGM cells on CRC development was evaluated by adoptive transfer assays.

RESULTS

ThGM cells, which expressed granulocyte-macrophage-colony-stimulating factor (GM-CSF), accumulated in CRC tissues. mTORC1 signaling is activated in CRC ThGM cells. mTORC1 inhibition by rapamycin suppressed ThGM cell differentiation and proliferation and resulted in the death of differentiating ThGM cells. mTORC1 inhibition in already differentiated ThGM cells did not induce significant cell death but decreased the expression of GM-CSF, interleukin-2, and tumor necrosis factor-alpha while impeding cell proliferation. Furthermore, mTORC1 inhibition diminished the effect of ThGM cells on driving macrophage polarization toward the M1 type, as evidenced by lower expression of pro-inflammatory cytokines, major histocompatibility complex class II molecule, and CD80 in macrophages after co-culture with rapamycin-treated ThGM cells. Lentivirus-mediated knockdown/overexpression of regulatory-associated protein of mTOR (Raptor) confirmed the essential role of mTORC1 in ThGM cell differentiation and function. Adoptively transferred ThGM cells suppressed CRC growth whereas mTORC1 inhibition abolished this effect.

CONCLUSION

mTORC1 is essential for the anti-CRC activity of ThGM cells.

Single cell dynamics of tumor specificity vs bystander activity in CD8+ T cells define the diverse immune landscapes in colorectal cancer

CD8+ T cell activation via immune checkpoint blockade (ICB) is successful in microsatellite instable (MSI) colorectal cancer (CRC) patients. By comparison, the success of immunotherapy against microsatellite stable (MSS) CRC is limited. Little is known about the most critical features of CRC CD8+ T cells that together determine the diverse immune landscapes and contrasting ICB responses. Hence, we pursued a deep single cell mapping of CRC CD8+ T cells on transcriptomic and T cell receptor (TCR) repertoire levels in a diverse patient cohort, with additional surface proteome validation. This revealed that CRC CD8+ T cell dynamics are underscored by complex interactions between interferon-γ signaling, tumor reactivity, TCR repertoire, (predicted) TCR antigen-specificities, and environmental cues like gut microbiome or colon tissue-specific 'self-like' features. MSI CRC CD8+ T cells showed tumor-specific activation reminiscent of canonical 'T cell hot' tumors, whereas the MSS CRC CD8+ T cells exhibited tumor unspecific or bystander-like features. This was accompanied by inflammation reminiscent of 'pseudo-T cell hot' tumors. Consequently, MSI and MSS CRC CD8+ T cells showed overlapping phenotypic features that differed dramatically in their TCR antigen-specificities. Given their high discriminating potential for CD8+ T cell features/specificities, we used the single cell tumor-reactive signaling modules in CD8+ T cells to build a bulk tumor transcriptome classification for CRC patients. This "Immune Subtype Classification" (ISC) successfully distinguished various tumoral immune landscapes that showed prognostic value and predicted immunotherapy responses in CRC patients. Thus, we deliver a unique map of CRC CD8+ T cells that drives a novel tumor immune landscape classification, with relevance for immunotherapy decision-making.

Sirtuin 2 up-regulation suppresses the anti-tumour activity of exhausted natural killer cells in mesenteric lymph nodes in murine colorectal carcinoma

Natural killer (NK) cells inhibit colorectal carcinoma (CRC) initiation and progression through their tumoricidal activity. However, cumulative evidence suggests that NK cells become functionally exhausted in patients with CRC. To deepen the understanding of the mechanisms underlying CRC-associated NK cell exhaustion, we explored the expression and effect of Sirtuin 2 (Sirt2) in mesenteric lymph node (mLN) NK cells in a murine colitis-associated CRC model. Sirt2 was remarkably up-regulated in mLN NK cells after CRC induction. Particularly, Sirt2 was increased in mLN NK cells expressing high T cell immunoglobulin and mucin domain-3 (TIM3), high lymphocyte activation protein-3 (LAG3), high programmed death-1 (PD-1), high T cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT), high NK group 2 member A (NKG2A), but low tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), low interferon-gamma and low granzyme B. In addition, Sirt2 was also increased in NK cells after induction of exhaustion in vitro. Lentivirus-mediated Sirt2 silencing did not affect the acute activation and cytotoxicity of non-exhausted NK cells. However, Sirt2 silencing partially restored the expression of interferon-gamma, granzyme B and CD107a in exhausted NK cells. Meanwhile, Sirt2 silencing down-regulated TIM3, LAG3, TIGIT and NKG2A while up-regulated TRAIL on exhausted NK cells. Consequently, Sirt2 silencing restored the cytotoxicity of exhausted NK cells. Moreover, Sirt2 silencing partially ameliorates the defects in glycolysis and mitochondrial respiration of exhausted NK cells, as evidenced by increases in glycolytic capacity, glycolytic reserve, basal respiration, maximal respiration and spare respiration capacity. Accordingly, Sirt2 negatively regulates the tumoricidal activity of exhausted NK cells in CRC.

A comprehensive review of Tripterygium wilfordii hook. f. in the treatment of rheumatic and autoimmune diseases: Bioactive compounds, mechanisms of action, and future directions

Rheumatic and autoimmune diseases are a group of immune system-related disorders wherein the immune system mistakenly attacks and damages the body's tissues and organs. This excessive immune response leads to inflammation, tissue damage, and functional impairment. Therapeutic approaches typically involve medications that regulate immune responses, reduce inflammation, alleviate symptoms, and target specific damaged organs. Tripterygium wilfordii Hook. f., a traditional Chinese medicinal plant, has been widely studied in recent years for its application in the treatment of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, and multiple sclerosis. Numerous studies have shown that preparations of Tripterygium wilfordii have anti-inflammatory, immunomodulatory, and immunosuppressive effects, which effectively improve the symptoms and quality of life of patients with autoimmune diseases, whereas the active metabolites of T. wilfordii have been demonstrated to inhibit immune cell activation, regulate the production of inflammatory factors, and modulate the immune system. However, although these effects contribute to reductions in inflammatory responses and the suppression of autoimmune reactions, as well as minimize tissue and organ damage, the underlying mechanisms of action require further investigation. Moreover, despite the efficacy of T. wilfordii in the treatment of autoimmune diseases, its toxicity and side effects, including its potential hepatotoxicity and nephrotoxicity, warrant a thorough assessment. Furthermore, to maximize the therapeutic benefits of this plant in the treatment of autoimmune diseases and enable more patients to utilize these benefits, efforts should be made to strengthen the regulation and standardized use of T. wilfordii.

Asthma is associated with a lower incidence of metastatic colorectal cancer in a US patient cohort

In previous pre-clinical studies, we examined the contribution of interleukin 4 receptor (IL4R) signaling in the progression and metastasis of colorectal cancer (CRC). Aberrant activation of this receptor can result in atopic diseases such as asthma. We hypothesized that further evidence for the contribution of excessive IL4R being associated with CRC progression could be seen in medical records, and specifically that chronic asthma patients were more likely to be diagnosed with metastatic CRC. To test this hypothesis, we took advantage of the Synthetic Derivative, a resource developed at Vanderbilt University Medical Center that hosts de-identified data taken from the electronic medical record. We developed search protocols that produced retrospective cohorts of invasive CRC patients and cancer-free equivalents. In comparing 787 metastatic CRC patients to 238 non-metastatic patients, we actually found significantly fewer asthmatics went on to develop metastatic CRC (P=0.0381). By comparing these groups together against 1197 cancer-free patients, even fewer asthmatic patients would develop invasive CRC (P<0.0001). While these results are clearly in opposition to our original hypothesis, they still support a link between chronic asthma and metastatic CRC development. One intriguing possibility, that will be examined in the future, is whether treatment for chronic asthma may be responsible for the reduction in metastatic cancer.

IMMUNOREACT 0: Biopsy-based immune biomarkers as predictors of response to neoadjuvant therapy for rectal cancer-A systematic review and meta-analysis

BACKGROUND

The main therapy for rectal cancer patients is neoadjuvant therapy (NT) followed by surgery. Immune biomarkers are emerging as potential predictors of the response to NT. We performed a meta-analysis to estimate their predictive significance.

METHODS

A systematic literature search of PubMed, Ovid MEDLINE and EMBASE databases was performed to identify eligible studies. Studies on patients with rectal cancer undergoing NT in which the predictive significance of at least one of the immunological markers of interest was assessed by immunohistochemistry (IHC) in pretreatment biopsies were included.

RESULTS

Seventeen studies reporting sufficient data met the inclusion criteria for meta-analysis. High levels of total CD3+, CD4+ and CD8+ tumor infiltrating lymphocytes (TILs), as well as stromal and intraepithelial CD8+ compartments, significantly predicted good pathological response to NT. Moreover, high levels of total (tumoral and immune cell expression) PD-L1 resulted associated to a good pathological response. On the contrary, high levels of intraepithelial CD4+ TILs were correlated with poor pathological response. FoxP3+ TILs, tumoral PD-L1 and CTLA-4 were not correlated to the treatment response.

CONCLUSION

This meta-analysis indicated that high-density TILs might be predictive biomarkers of pathological response in patients that underwent NT for rectal cancer.

Identification of genes critical for inducing ulcerative colitis and exploring their tumorigenic potential in human colorectal carcinoma

Ulcerative colitis (UC) is a chronic relapsing inflammatory bowel disease leading to continuous mucosal inflammation in the rectum extending proximally towards the colon. Chronic and/or recurrent UC is one of the critical predisposing mediators of the oncogenesis of human colorectal carcinoma (CRC). Perturbations of the differential expression of the UC-critical genes exert an intense impact on the neoplastic transformation of the affected tissue(s). Herein, a comprehensive exploration of the UC-critical genes from the transcriptomic profiles of UC patients was conducted to study the differential expression, functional enrichment, genomic alterations, signal transduction pathways, and immune infiltration level encountered by these genes concerning the oncogenesis of CRC. The study reveals that WFDC2, TTLL12, THRA, and EPHB3 play crucial roles as UC-CRC critical genes and are positively correlated with the molecular transformation of UC to CRC. Taken together, these genes can be used as potential biomarkers and therapeutic targets for combating UC-induced human CRC.

Protein expression of S100A2 reveals it association with patient prognosis and immune infiltration profile in colorectal cancer

PURPOSE

Colorectal cancer (CRC) is the third most diagnosed cancer worldwide. Despite a well-established knowledge of tumour development, biomarkers to predict patient outcomes are still required. S100 calcium-binding protein A2 (S100A2) has been purposed as a potential marker in many types of cancer, however, the prognostic value of S100A2 in CRC is rarely reported.

MATERIAL AND METHODS

In this study, immunohistochemistry (IHC) was performed to identify the prognostic role of S100A2 protein expression in the tumour core of the tissue microarrays (TMAs) in colorectal cancer patients (n=787). Bulk RNA transcriptomic data was used to identify significant genes compared between low and high cytoplasmic S100A2 groups. Multiplex immunofluorescence (mIF) was performed to further study and confirm the immune infiltration in tumours with low and high cytoplasmic S100A2.

RESULTS

Low cytoplasmic protein expression of S100A2 in the tumour core was associated with poor survival (HR 0.539, 95%CI 0.394-0.737, P<0.001) and other adverse tumour phenotypes. RNA transcriptomic analysis showed a gene significantly associated with the low cytoplasmic S100A2 group (AKT3, TAGLN, MYLK, FGD6 and ETFDH), which correlated with tumour development and progression. GSEA analysis identifies the enriched anti-tumour and immune activity group of genes in high cytoplasmic S100A2. Additionally, mIF staining showed that high CD3+FOXP3+ and CD163+ inversely associated with low cytoplasmic S100A2 (P<0.001, P=0.009 respectively).

CONCLUSION

Our finding demonstrates a prognostic value of S100A2 together with the correlation with immune infiltration in CRC.

VAX014, an Oncolytic Therapy, Reduces Adenomas and Modifies Colon Microenvironment in Mouse Model of CRC

Colorectal cancer (CRC) remains the third most common form of cancer and, despite its reduced mortality, results in over 50,000 deaths annually, highlighting the need for novel therapeutic approaches. VAX014 is a novel clinical-stage, oncolytic bacterial minicell-based therapy shown to elicit protective antitumor immune responses in cancer, but it has not been fully evaluated in CRC. Here, VAX014 was demonstrated to induce oncolysis in CRC cell lines in vitro and was evaluated in vivo, both as a prophylactic (before spontaneous development of adenomatous polyps) and as a neoadjuvant treatment using the Fabp-CreXApc^fl468 preclinical animal model of colon cancer. As a prophylactic, VAX014 significantly reduced the size and number of adenomas without inducing long term changes in the gene expression of inflammatory, T helper 1 antitumor, and immunosuppression markers. In the presence of adenomas, a neoadjuvant VAX014 treatment reduced the number of tumors, induced the gene expression of antitumor T_H1 immune markers in adenomas, and promoted the expansion of the probiotic bacterium Akkermansia muciniphila. The neoadjuvant VAX014 treatment was associated with decreased Ki67 proliferation in vivo, suggesting that VAX014 inhibits adenoma development through both oncolytic and immunotherapeutic effects. Combined, these data support the potential of VAX014 treatment in CRC and "at risk" polyp-bearing or early adenocarcinoma populations.

Sirtuin 6 is a negative regulator of the anti-tumor function of natural killer cells in murine inflammatory colorectal cancer

The immune system plays a crucial role in controlling colorectal cancer (CRC) development. Natural killer (NK) cells are tumoricidal but undergo exhaustion in CRC patients. The current research aims to understand the role of sirtuin 6 (SIRT6) in CRC-associated NK cell exhaustion in a murine inflammatory colorectal cancer model. To this end, inflammatory CRC was induced by treating mice with azoxymethane plus dextran sulfate sodium. The expression of SIRT6 in NK cells in murine mesenteric lymph nodes (mLNs) and the CRC tissue was characterized by Immunoblotting. SIRT6 knockdown was achieved by lentiviral transduction of murine splenic NK cells, followed by evaluation of NK cell proliferation and the expression of cytotoxic mediators using flow cytometry. NK cell cytotoxicity was measured by cytotoxicity assays. Adoptive transfer of murine NK cells was applied to analyze the effect of SIRT6 knockdown in vivo. We found that SIRT6 was up-regulated in infiltrating NK cells in the murine CRC tissue, especially NK cells with an exhausted phenotype and impaired cytotoxicity. SIRT6 knockdown significantly boosted murine splenic NK cell functionality, as evidenced by accelerated proliferation, increased production of cytotoxic mediators, and higher tumoricidal activity both in vitro and in vivo. Furthermore, the adoptive transfer of SIRT6-knockdown NK cells into CRC-bearing mice effectively suppressed CRC progression. Therefore, SIRT6 up-regulation is essential for murine NK cell exhaustion in CRC because it impedes the tumoricidal activity of murine NK cells. Artificial SIRT6 down-regulation could boost the function of infiltrating NK cells to oppress CRC progression in mice.

Tumor lineage-specific immune response in brain metastatic disease: opportunities for targeted immunotherapy regimen?

Metastases in the brain are the most severe and devastating complication of cancer. The incidence of brain metastasis is increasing. Therefore, the need of finding specific druggable targets for brain metastasis is demanding. The aim of this study was to compare the brain (immune) response to brain metastases of the most common tumor lineages, viz., lung adenocarcinoma and breast cancer. Targeted gene expression profiles of 11 brain metastasis of lung adenocarcinoma (BM-LUAD) were compared to 11 brain metastasis of breast cancer (BCBM) using NanoString nCounter PanCancer IO 360™ Panel. The most promising results were validated spatially using the novel GeoMx™ Digital Spatial Profiler (DSP) Technology. Additionally, Immune cell profiles and expression of drug targets were validated by multiplex immunohistochemistry. We found a more active immune response in BM-LUAD as compared to BCBM. In the BM-LUAD, 138 genes were upregulated as compared to BCBM (adj. p ≤ 0.05). Conversely, in BCBM 28 genes were upregulated (adj. p ≤ 0.05). Additionally, genes related to CD45 + cells, T cells, and cytotoxic T cells showed to be expressed higher in BM-LUAD compared to BCBM (adj. p = 0.01, adj. p = 0.023, adj. p = 0.023, respectively). The spatial quantification of the immune cells using the GeoMx DSP technique revealed the significantly higher quantification of CD14 and CD163 in tumor regions of BM-LUAD as compared to BCBM. Importantly, the immune checkpoint VISTA and IDO1 were identified as highly expressed in the BM-LUAD. Multiplex immunohistochemistry confirmed the finding and showed that VISTA is expressed mainly in BM-LUAD tumor cells, CD3 + cells, and to fewer levels in some microglial cells in BM-LUAD. This is the first report on differences in the brain immune response between metastatic tumors of different lineages. We found a far more extensive infiltration of immune cells in BM-LUAD as compared to BCBM. In addition, we found higher expression of VISTA and IDO1 in BM-LUAD. Taken together, targeted immune therapy should be considered to treat patients with BM-LUAD.

F4/80+Ly6Chigh Macrophages Lead to Cell Plasticity and Cancer Initiation in Colitis

BACKGROUND & AIMS

Colorectal cancer is a leading cause of cancer death, and a major risk factor is chronic inflammation. Despite the link between colitis and cancer, the mechanism by which inflammation leads to colorectal cancer is not well understood.

METHODS

To investigate whether different forms of inflammation pose the same risk of cancer, we compared several murine models of colitis (dextran sodium sulfate [DSS], 2,4,6-trinitrobenzene sulfonic acid, 4-ethoxylmethylene-2-phenyloxazol-5-one, Citrobacter rodentium, Fusobacterium nucleatum, and doxorubicin) with respect to their ability to lead to colonic tumorigenesis. We attempted to correlate the severity of colitis and inflammatory profile with the risk of tumorigenesis in both azoxymethane-dependent and Dclk1/APCfl/fl murine models of colitis-associated cancer.

RESULTS

DSS colitis reproducibly led to colonic tumors in both mouse models of colitis-associated cancer. In contrast, all other forms of colitis did not lead to cancer. When compared with the colitis not associated with tumorigenesis, DSS colitis was characterized by significantly increased CD11b+F4/80+Ly6Chigh macrophages and CD11b+Ly6G+ neutrophils. Interestingly, depletion of the CD11b+F4/80+Ly6Chigh macrophages inhibited tumorigenesis, whereas depletion of CD11b+Ly6G+ neutrophils had no effect on tumorigenesis. Furthermore, the macrophage-derived cytokines interleukin-1β, tumor necrosis factor-α, and interleukin-6 were significantly increased in DSS colitis and promoted stemness of Dclk1+ tuft cells that serve as the cellular origin of cancer.

CONCLUSIONS

We have identified CD11b+F4/80+Ly6Chigh macrophages as key mediators of cancer initiation in colitis-associated cancer. Development of new therapies that target these cells may provide an effective preventative strategy for colitis-associated cancer.

Association between C-reactive protein-albumin-lymphocyte (CALLY) index and overall survival in patients with colorectal cancer: From the investigation on nutrition status and clinical outcome of common cancers study

Background

Colorectal cancer (CRC) is among the most common malignant cancers worldwide, and its development is influenced by inflammation, nutrition, and the immune status. Therefore, we combined C-reactive protein (CRP), albumin, and lymphocyte, which could reflect above status, to be the CRP-albumin-lymphocyte (CALLY) index, and evaluated its association with overall survival (OS) in patients with CRC.

Methods

The clinicopathological and laboratory characteristics of 1260 patients with CRC were collected from the Investigation on Nutrition Status and Clinical Outcome of Common Cancers (INSCOC) study. Cox regression analysis was performed to assess the association between the CALLY index and OS. A nomogram including sex, age, the CALLY index and TNM stage was constructed. The Concordance Index (C-index) was utilized to evaluate the prognostic value of the CALLY index and classical CRC prognostic factors, such as modified Glasgow prognostic score (mGPS), neutrocyte to lymphocyte ratio (NLR), systemic immune inflammation index (SII), and platelet to lymphocyte ratio (PLR), as well as to assess the prognostic value of the nomogram and TNM stage.

Results

Multivariate Cox regression analyses demonstrated that the CALLY index was independently associated with OS in patients with CRC [Hazard ratio (HR) = 0.91, 95% confidence interval (CI) = 0.87-0.95, P&lt;0.001]. The CALLY index showed the highest prognostic value (C-index = 0.666, 95% CI = 0.638-0.694, P&lt;0.001), followed by mGPS, NLR, SII, and PLR. The nomogram demonstrated higher prognostic value (C-index = 0.784, 95% CI = 0.762-0.807, P&lt;0.001) than the TNM stage.

Conclusion

The CALLY index was independently associated with OS in patients with CRC and showed higher prognostic value than classical CRC prognostic factors. The nomogram could provide more accurate prognostic prediction than TNM stage.

A glimpse of research cores and frontiers on the relationship between long noncoding RNAs (lncRNAs) and colorectal cancer (CRC) using the VOSviewer tool

As lncRNAs are essential participants in colorectal carcinogenesis. This study aimed to use the VOSviewer tool to access the research cores and frontiers on the relationship between lncRNAs and CRC. Our findings showed that the mechanism of lncRNA in the occurrence and development of CRC was the core theme of the field. (1) Immunotherapy and immune microenvironment of CRC and lncRNAs, (2) CRC and lncRNAs in exosomes and (3) CRC and lncRNA-targeted therapy might represent three research frontiers. A comprehensive understanding of their existing mechanisms and the search for new regulatory paradigms are the core topics of future research. This knowledge will also help us select appropriate targeting methods and select appropriate preclinical models to promote clinical translation and ultimately achieve precise treatment of CRC.

Identification of prognostic immune-related lncRNA signature predicting the overall survival for colorectal cancer

Long non-coding RNA (lncRNA) is an important regulator of gene expression and serves a fundamental role in immune regulation. The present study aimed to develop a novel immune-related lncRNA signature to assess the prognosis of patients with colorectal cancer (CRC). Transcriptome data and clinical information of patients with CRC were downloaded from The Cancer Genome Atlas (TCGA) and UCSC Xena platforms. Immune-related mRNAs were extracted from the Molecular Signatures Database (MSigDB), and the immune-related lncRNAs were identified based on correlation analysis. Then, univariate, Lasso and multivariate Cox regression were applied to construct an immune-related lncRNA signature, and CRC patients were divided into high- and low-risk groups according to the median risk score. Finally, we evaluated the signature from the perspectives of clinical outcome, clinicopathological parameters, tumor-infiltrating immune cells (TIICs), immune status, tumor mutation burden (TMB) and immunotherapy responsiveness. In total, 272 immune-related lncRNAs were identified, five of which were applied to construct an immune-related lncRNA signature. The signature divided patients with CRC into low- and high-risk groups, the prognosis of patients in the high-risk group were significantly poorer than those in low-risk group, and the results were further confirmed in external validation cohort. Furthermore, the high-risk group showed aggressive clinicopathological characteristics, specific TIIC and immune function status, and low sensitivity to immunotherapy. The immune-related lncRNA signature could be exploited as a promising biomarker for predicting the prognosis and immune status of patients with CRC.

Tumor-derived extracellular vesicles in the colorectal cancer immune environment and immunotherapy

Despite significant advances in the screening, diagnosis, and treatment of colorectal cancer (CRC) immune checkpoint inhibitors (ICIs) continue to have limited utility outside of microsatellite-high disease. Given the durable response to immunotherapy seen across malignancies, increasing CRC response rates to ICI therapy is an active area of clinical research. An increasing body of work has demonstrated that tumor-derived extracellular vesicles (TEVs) are key modulators in tumor signaling and the determinants of the tumor microenvironment. Pre-clinical models have shown that TEVs are directly involved in antigen presentation and are involved in radiation-induced DNA damage signaling. Both direct and indirect modifications of these TEVs can alter CRC immunogenicity and ICI treatment response, making them attractive targets for potential therapeutic development. In addition, modified TEVs can be developed using several different mechanisms, with varied cargo including micro-RNAs and small peptide molecules. Recent work has shown strong pre-clinical evidence of injected modified TEV-induced ICI activity, with knockdown of the micro-RNA miR-424 in TEVs improving CRC immunogenicity and increasing anti-PD-1 activity in mouse models. Clinical trials are ongoing in the evaluation of modified TEVs in cancer therapy, but they appear to be a promising therapeutic target in CRC.

A Reduction of Calcineurin Inhibitors May Improve Survival in Patients with De Novo Colorectal Cancer after Liver Transplantation

Background and Objectives: After liver transplantation (LT), long-term immunosuppression (IS) is essential. IS is associated with de novo malignancies, and the incidence of colorectal cancer (CRC) is increased in LT patients. We assessed course of disease in patients with de novo CRC after LT with focus of IS and impact on survival in a retrospective, single-center study. Materials and Methods: All patients diagnosed with CRC after LT between 1988 and 2019 were included. The management of IS regimen following diagnosis and the oncological treatment approach were analyzed: Kaplan−Meier analysis as well as univariate and multivariate analysis were performed. Results: A total of 33 out of 2744 patients were diagnosed with CRC after LT. Two groups were identified: patients with restrictive IS management undergoing dose reduction (RIM group, n = 20) and those with unaltered regimen (maintenance group, n = 13). The groups did not differ in clinical and oncological characteristics. Statistically significant improved survival was found in Kaplan−Meier analysis for patients in the RIM group with 83.46 (8.4−193.1) months in RIM and 24.8 (0.5−298.9) months in the maintenance group (log rank = 0.02) and showed a trend in multivariate cox regression (p = 0.054, HR = 14.3, CI = 0.96−213.67). Conclusions: Immunosuppressive therapy should be reduced further in patients suffering from CRC after LT in an individualized manner to enable optimal oncological therapy and enable improved survival.

Identification and validation of a novel signature as a diagnostic and prognostic biomarker in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most common malignant neoplasms worldwide. Although marker genes associated with CRC have been identified previously, only a few have fulfilled the therapeutic demand. Therefore, based on differentially expressed genes (DEGs), this study aimed to establish a promising and valuable signature model to diagnose CRC and predict patient's prognosis.

METHODS

The key genes were screened from DEGs to establish a multiscale embedded gene co-expression network, protein-protein interaction network, and survival analysis. A support vector machine (SVM) diagnostic model was constructed by a supervised classification algorithm. Univariate Cox analysis was performed to construct two prognostic signatures for overall survival and disease-free survival by Kaplan-Meier analysis, respectively. Independent clinical prognostic indicators were identified, followed by univariable and multivariable Cox analysis. GSEA was used to evaluate the gene enrichment analysis and CIBERSORT was used to estimate the immune cell infiltration. Finally, key genes were validated by qPCR and IHC.

RESULTS

In this study, four key genes (DKC1, FLNA, CSE1L and NSUN5) were screened. The SVM diagnostic model, consisting of 4-gene signature, showed a good performance for the diagnostic (AUC = 0.9956). Meanwhile, the four-gene signature was also used to construct a risk score prognostic model for disease-free survival (DFS) and overall survival (OS), and the results indicated that the prognostic model performed best in predicting the DFS and OS of CRC patients. The risk score was validated as an independent prognostic factor to exhibit the accurate survival prediction for OS according to the independent prognostic value. Furthermore, immune cell infiltration analysis demonstrated that the high-risk group had a higher proportion of macrophages M0, and T cells CD4 memory resting was significantly higher in the low-risk group than in the high-risk group. In addition, functional analysis indicated that WNT and other four cancer-related signaling pathways were the most significantly enriched pathways in the high-risk group. Finally, qRT-PCR and IHC results demonstrated that the high expression of DKC1, CSE1L and NSUN5, and the low expression of FLNA were risk factors of CRC patients with a poor prognosis.

CONCLUSION

In this study, diagnosis and prognosis models were constructed based on the screened genes of DKC1, FLNA, CSE1L and NSUN5. The four-gene signature exhibited an excellent ability in CRC diagnosis and prognostic prediction. Our study supported and highlighted that the four-gene signature is conducive to better prognostic risk stratification and potential therapeutic targets for CRC patients.

Parvimonas micra is associated with tumour immune profiles in molecular subtypes of colorectal cancer

The importance of the tumour microbiome in different aspects of colorectal cancer (CRC) has been increasingly recognised, but many questions remain. The aim of this study was to explore the effect of specific CRC associated microbes on the tumour immune response, which has a considerable prognostic value in CRC. We applied specific qPCR to detect Parvimonas micra and Fusobacterium nucleatum in tumour tissues from an immunologically well-characterised cohort of 69 CRC patients. This cohort included detailed analyses of immune profiles based on flow cytometry and transcriptomics in tumour tissue and blood, along with comprehensive analyses of molecular subtypes. P. micra and F. nucleatum were detected in 24% and 64% of tumour tissues, respectively. We found a significant association of P. micra with high-grade tumours and tumours of CMS1 subtype. F. nucleatum was significantly associated with right-sided tumours, microsatellite instability, and CMS1 tumours. The immunological analyses revealed significant associations of P. micra with activated CD69⁺ T lymphocytes and increased antigen-presenting HLA-DR⁺ B lymphocytes. P. micra was also positively associated with M1 and M2 macrophage traits. The impact of P. micra tumour colonisation on the immune response was further assessed using transcriptomics in validation of our findings. No associations were found between F. nucleatum and immune profiles in this study. Our findings support novel associations between P. micra and the immune response in CRC. A better understanding of these interactions might help to identify important predictive and prognostic tools as well as new targets for therapy.

Complement downregulation promotes an inflammatory signature that renders colorectal cancer susceptible to immunotherapy

BACKGROUND AND AIMS

The role of inflammatory immune responses in colorectal cancer (CRC) development and response to therapy is a matter of intense debate. While inflammation is a known driver of CRC, inflammatory immune infiltrates are a positive prognostic factor in CRC and predispose to response to immune checkpoint blockade (ICB) therapy. Unfortunately, over 85% of CRC cases are primarily unresponsive to ICB due to the absence of an immune infiltrate, and even the cases that show an initial immune infiltration can become refractory to ICB. The identification of therapy supportive immune responses in the field has been partially hindered by the sparsity of suitable mouse models to recapitulate the human disease. In this study, we aimed to understand how the dysregulation of the complement anaphylatoxin C3a receptor (C3aR), observed in subsets of patients with CRC, affects the immune responses, the development of CRC, and response to ICB therapy.

METHODS

We use a comprehensive approach encompassing analysis of publicly available human CRC datasets, inflammation-driven and newly generated spontaneous mouse models of CRC, and multiplatform high-dimensional analysis of immune responses using microbiota sequencing, RNA sequencing, and mass cytometry.

RESULTS

We found that patients' regulation of the complement C3aR is associated with epigenetic modifications. Specifically, downregulation of C3ar1 in human CRC promotes a tumor microenvironment characterized by the accumulation of innate and adaptive immune cells that support antitumor immunity. In addition, in vivo studies in our newly generated mouse model revealed that the lack of C3a in the colon activates a microbiota-mediated proinflammatory program which promotes the development of tumors with an immune signature that renders them responsive to the ICB therapy.

CONCLUSIONS

Our findings reveal that C3aR may act as a previously unrecognized checkpoint to enhance antitumor immunity in CRC. C3aR can thus be exploited to overcome ICB resistance in a larger group of patients with CRC.

Checkpoint molecules on infiltrating immune cells in colorectal tumor microenvironment

Colorectal cancer (CRC) is one of the most prevalent cancer types worldwide, with a high mortality rate due to metastasis. The tumor microenvironment (TME) contains multiple interactions between the tumor and the host, thus determining CRC initiation and progression. Various immune cells exist within the TME, such as tumor-infiltrating lymphocytes (TILs), tumor-associated macrophages (TAMs), and tumor-associated neutrophils (TANs). The immunotherapy approach provides novel opportunities to treat solid tumors, especially toward immune checkpoints. Despite the advances in the immunotherapy of CRC, there are still obstacles to successful treatment. In this review, we highlighted the role of these immune cells in CRC, with a particular emphasis on immune checkpoint molecules involved in CRC pathogenesis.

Interaction between microbiota and immunity and its implication in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related death in the world. Besides genetic causes, colonic inflammation is one of the major risk factors for CRC development, which is synergistically regulated by multiple components, including innate and adaptive immune cells, cytokine signaling, and microbiota. The complex interaction between CRC and the gut microbiome has emerged as an important area of current CRC research. Metagenomic profiling has identified a number of prominent CRC-associated bacteria that are enriched in CRC patients, linking the microbiota composition to colitis and cancer development. Some microbiota species have been reported to promote colitis and CRC development in preclinical models, while a few others are identified as immune modulators to induce potent protective immunity against colitis and CRC. Mechanistically, microbiota regulates the activation of different immune cell populations, inflammation, and CRC via crosstalk between innate and adaptive immune signaling pathways, including nuclear factor kappa B (NF-κB), type I interferon, and inflammasome. In this review, we provide an overview of the potential interactions between gut microbiota and host immunity and how their crosstalk could synergistically regulate inflammation and CRC, thus highlighting the potential roles and mechanisms of gut microbiota in the development of microbiota-based therapies to prevent or alleviate colitis and CRC.