The Regulation of Intestinal Inflammation and Cancer Development by Type 2 Immune Responses

Colorectal cancer and inulin supplementation: the good, the bad, and the unhelpful

The prebiotic inulin has been vaunted for its potential to reduce the risk of colorectal cancer. Inulin fermentation resulting in the production of short-chain fatty acids, primarily butyrate, has been reported to be associated with properties that are beneficial for gut health and has led to an increased consumption of inulin in the Western population through processed food and over-the-counter dietary supplements. However, in clinical trials, there is limited evidence of the efficacy of inulin in preventing colorectal cancer. Moreover, recent data suggest that improper inulin consumption may even be harmful for gastro-intestinal health under certain circumstances. The main objective of this review is to provide insight into the beneficial and potentially detrimental effects of inulin supplementation in the context of colorectal cancer prevention and enhancement of treatment efficacy.

Phytochemicals as Immunomodulatory Molecules in Cancer Therapeutics

Phytochemicals are natural plant-derived products that provide significant nutrition, essential biomolecules, and flavor as part of our diet. They have long been known to confer protection against several diseases via their anti-inflammatory, immune-regulatory, anti-microbial, and several other properties. Deciphering the role of phytochemicals in the prevention, inhibition, and treatment of cancer-unrestrained cell proliferation due to the loss of tight regulation on cell growth and replication-has been the focus of recent research. Particularly, the immunomodulatory role of phytochemicals, which is pivotal in unchecked cell proliferation and metastasis, has recently been studied extensively. The immune system is a critical component of the tumor microenvironment, and it plays essential roles in both preventing and promoting oncogenesis. Immunomodulation includes stimulation, amplification, or inactivation of some stage(s) of the immune response. Phytochemicals and their products have demonstrated immune regulation, such as macrophage migration, nitric oxide synthase inhibition, lymphocyte, T-cell, and cytokine stimulation, natural killer cell augmentation, and NFκB, TNF, and apoptosis regulation. There is a dearth of extensive accounts of the immunomodulatory effects of phytochemicals in cancer; thus, we have compiled these effects with mechanistic aspects of dietary phytochemicals in cancer, highlighting promising candidates and ongoing clinical trials on immunotherapeutic strategies to mitigate oncogenesis.

Microbial Components and Effector Molecules in T Helper Cell Differentiation and Function

The mammalian intestines harbor trillions of commensal microorganisms composed of thousands of species that are collectively called gut microbiota. Among the microbiota, bacteria are the predominant microorganism, with viruses, protozoa, and fungi (mycobiota) making up a relatively smaller population. The microbial communities play fundamental roles in the maturation and orchestration of the immune landscape in health and disease. Primarily, the gut microbiota modulates the immune system to maintain homeostasis and plays a crucial role in regulating the pathogenesis and pathophysiology of inflammatory, neuronal, and metabolic disorders. The microbiota modulates the host immune system through direct interactions with immune cells or indirect mechanisms such as producing short-chain acids and diverse metabolites. Numerous researchers have put extensive efforts into investigating the role of microbes in immune regulation, discovering novel immunomodulatory microbial species, identifying key effector molecules, and demonstrating how microbes and their key effector molecules mechanistically impact the host immune system. Consequently, recent studies suggest that several microbial species and their immunomodulatory molecules have therapeutic applicability in preclinical settings of multiple disorders. Nonetheless, it is still unclear why and how a handful of microorganisms and their key molecules affect the host immunity in diverse diseases. This review mainly discusses the role of microbes and their metabolites in T helper cell differentiation, immunomodulatory function, and their modes of action.

Distinct T helper cell-mediated antitumor immunity: T helper 2 cells in focus

The adaptive arm of the immune system is crucial for appropriate antitumor immune responses. It is generally accepted that clusters of differentiation 4+ (CD4+) T cells, which mediate T helper (Th) 1 immunity (type 1 immunity), are the primary Th cell subtype associated with tumor elimination. In this review, we discuss evidence showing that antitumor immunity and better prognosis can be associated with distinct Th cell subtypes in experimental mouse models and humans, with a focus on Th2 cells. The aim of this review is to provide an overview and understanding of the mechanisms associated with different tumor outcomes in the face of immune responses by focusing on the (1) site of tumor development, (2) tumor properties (i. e., tumor metabolism and cytokine receptor expression), and (3) type of immune response that the tumor initially escaped. Therefore, we discuss how low-tolerance organs, such as lungs and brains, might benefit from a less tissue-destructive immune response mediated by Th2 cells. In addition, Th2 cells antitumor effects can be independent of CD8+ T cells, which would circumvent some of the immune escape mechanisms that tumor cells possess, like low expression of major histocompatibility-I (MHC-I). Finally, this review aims to stimulate further studies on the role of Th2 cells in antitumor immunity and briefly discusses emerging treatment options.

Setd2 supports GATA3+ST2+ thymic-derived Treg cells and suppresses intestinal inflammation

Treg cells acquire distinct transcriptional properties to suppress specific inflammatory responses. Transcription characteristics of Treg cells are regulated by epigenetic modifications, the mechanism of which remains obscure. Here, we report that Setd2, a histone H3K36 methyltransferase, is important for the survival and suppressive function of Treg cells, especially those from the intestine. Setd2 supports GATA3⁺ST2⁺ intestinal thymic-derived Treg (tTreg) cells by facilitating the expression and reciprocal relationship of GATA3 and ST2 in tTreg cells. IL-33 preferentially boosts Th2 cells rather than GATA3⁺ Treg cells in Foxp3^Cre-YFPSetd2 ^flox/flox mice, corroborating the constraint of Th2 responses by Setd2 expression in Treg cells. SETD2 sustains GATA3 expression in human Treg cells, and SETD2 expression is increased in Treg cells from human colorectal cancer tissues. Epigenetically, Setd2 regulates the transcription of target genes (including Il1rl1) by modulating the activity of promoters and intragenic enhancers where H3K36me3 is typically deposited. Our findings provide mechanistic insights into the regulation of Treg cells and intestinal immunity by Setd2.

Regulation of sleep disorders in patients with traumatic brain injury by intestinal flora based on the background of brain-gut axis

OBJECTIVE

This study investigates whether people with sleep disorders following traumatic brain injury exhibit altered intestinal flora. The changes may allow us to gain a better understanding of the role of intestinal flora in patients with sleep disorders after traumatic brain injury, which may give us insights into curing the sleep disorder after traumatic brain injury (TBI).

METHOD

We analyzed the intestinal microbial colony structure in the feces of the 28 patients in the normal sleep group and the sleep disorder group by 16SrDNAsequencing technology. The bioinformatics method was used to analyze the intestinal flora change in the v3-v4 region of patients with biorhythm disorder and to observe the difference between the two groups.

RESULTS

Group grouping comparison and analysis of the evolutionary cladistic map showed the intestinal flora of patients with normal sleep after TBI was mainly Bacilli and Lactobacillales, while that of patients with sleep disorders was mainly Lachnospiraceae and Bacteroidales. The histogram of group value distribution by grouping comparison and analysis showed that Lachnospiraceae, Bacteroidales, Bacteroidia, and Bacteroidetes were dominant in the sleep disorder group. A relative abundance map of species with significant differences by group grouping comparison showed the main manifestations of intestinal flora are Firmicutes, Bacilli, Lactobacillales, Streptococcaceae, and Bacteroidetes. The normal sleep group was dominated by Bacilli, Lactobacillales, Streptococcus, and Veillonella, while in the sleep disorder group, Lachnospiraceae, Bacteroidales, Bacteroidia, and Bacteroidetes were the main species. It was found that there were also significant differences in intestinal flora abundance between the two groups after TBI. After statistics processing, it was compared with the normal sleep group, Lactobacillus, Streptococcus, Oribacterium and Rothia, Actinomyces, Streptophyta, TM7-3 bacteria, and Serratia, showing a significant reduction in the sleep disorder group (P < 0.05). However, Odoribacter, Lachnospiraceae, and Bilophila increased significantly (P < 0.05).

CONCLUSION

The sleep disorders of patients after TBI can be closely related to intestinal flora disturbance, and its internal mechanism needs further study. Intestinal flora has the potential to be a new therapeutic target.

The Role and Interactions of Programmed Cell Death 4 and its Regulation by microRNA in Transformed Cells of the Gastrointestinal Tract

Data from GLOBOCAN 2020 estimates that there were 19.3 million new cases of cancer and 10.0 million cancer-related deaths in 2020 and that this is predicted to increase by 47% in 2040. The combined burden of cancers of the gastrointestinal (GI) tract, including oesophageal-, gastric- and colorectal cancers, resulted in 22.6% of the cancer-related deaths in 2020 and 18.7% of new diagnosed cases. Understanding the aetiology of GI tract cancers should have a major impact on future therapies and lessen this substantial burden of disease. Many cancers of the GI tract have suppression of the tumour suppressor Programmed Cell Death 4 (PDCD4) and this has been linked to the expression of microRNAs which bind to the untranslated region of PDCD4 mRNA and either inhibit translation or target the mRNA for degradation. This review highlights the properties of PDCD4 and documents the evidence for the regulation of PDCD4 expression by microRNAs in cancers of the GI tract.

Molecular Mechanisms of Tumor Immunomodulation in the Microenvironment of Colorectal Cancer

Colorectal cancer remains one of the most important health challenges in our society. The development of cancer immunotherapies has fostered the need to better understand the anti-tumor immune mechanisms at play in the tumor microenvironment and the strategies by which the tumor escapes them. In this review, we provide an overview of the molecular interactions that regulate tumor inflammation. We particularly discuss immunomodulatory cell-cell interactions, cell-soluble factor interactions, cell-extracellular matrix interactions and cell-microbiome interactions. While doing so, we highlight relevant examples of tumor immunomodulation in colorectal cancer.

COX-2 inhibitors decrease expression of PD-L1 in colon tumors and increase the influx of Type I tumor infiltrating lymphocytes

Colon cancer is initiated under inflammatory conditions associated with upregulation of immune checkpoint proteins. We evaluated immune modulation induced by non-steroidal anti-inflammatory agents used for colon cancer prevention. Both celecoxib and naproxen inhibited polyp growth in APC Min mice. Treatment of mice with either drug significantly decreased PD-L1 expression on polyps in a dose dependent manner (p<0.0001 for both). The decrease in PD-L1 was associated with an influx of CD8+ T-cells into polyps (p<0.0001, celecoxib; p=0.048, naproxen) compared to lesions from untreated animals and correlated with disease control. Naproxen is a nonselective inhibitor of both COX-1 and COX-2, and we questioned the role of the different cyclooxygenases in PD-L1 regulation. Silencing either COX-2 or COX-1 RNA in the murine colon cancer cell line MC38, reduced PD-L1 expression by 86% in COX-2-silenced cells (p<0.0001) while there was little effect with COX-1 siRNA compared to control. Naproxen could inhibit the growth of MC38 in vivo. Naproxen treated mice demonstrated a significant reduction in MC38 growth as compared to control (p<0001). Both Tbet+ CD4 and CD8 tumor infiltrating T-cells (TIL) were significantly increased (p=0.04 and p=0.038 respectively) without a concurrent increase in GATA3+ TIL (p>0.05). CD8+ TIL highly expressed the activation marker, CD69. Not only was PD-L1 expression decreased on tumors, but LAG3+CD8+ T-cells and PD-1 and LAG3 expression on T-regulatory cells was also reduced (p=0.008 and p=0.002 respectively). These data demonstrate COX-2 inhibitors significantly decrease PD-L1 in colonic lesions and favorably impact the phenotype of tumor infiltrating lymphocytes to control tumor growth.

Systemic Interleukins' Profile in Early and Advanced Colorectal Cancer

Tumor microenvironment (TME) is characterized by mutual interactions of the tumor, stromal and immune cells. Early and advanced colorectal tumors differ in structure and present altered serum cytokine levels. Mutual crosstalk among TME infiltrating cells may shift the balance into immune suppressive or pro-inflammatory, antitumor response this way influencing patients' prognosis. Cancer-related inflammation affects all the body and this way, the systemic level of cytokines could reflect TME processes. Despite numerous studies, it is still not known how systemic cytokines levels change during colorectal cancer (CRC) tumor development. Better understanding tumor microenvironment processes could help in planning therapeutic interventions and more accurate patient prognosis. To contribute to the comprehension of these processes within TME, we reviewed cytokines levels from clinical trials in early and advanced colorectal cancer. Presented data were analyzed in the context of experimental studies and studies analyzing tumor infiltration with immune cells. The review summarizes clinical data of cytokines secreted by tumor microenvironment cells: lymphocytes T helper 1 (Th1), lymphocytes T helper 2 (Th2), lymphocytes T helper 17 (Th17), regulatory T cells (Treg cells), regulatory T cells (Breg cells), M1/M2 macrophages, N1/N2 neutrophils, myeloid-derived suppressor cells (MDSC), dendritic cells (DC), innate lymphoid cells (ILC) natural killer (NK) cells and tumor cells.

Single Donor FMT Reverses Microbial/Immune Dysbiosis and Induces Clinical Remission in a Rat Model of Acute Colitis

Deviation in the gut microbial composition is involved in various pathologies, including inflammatory bowel disease (IBD). Faecal microbiota transplant (FMT) can act as a promising approach to treat IBD by which changes in microbiome can be reversed and homeostasis restored. Therefore, the aim of this study was to investigate the effect of FMT on the remission of acute inflammatory response using dextran sulfate sodium (DSS)-induced rat colitis model. Faecal microbial communities were analysed using the 16S rRNA approach, and clinical manifestations together with histological/haematological/biochemical/immunological analyses were assessed. Our study demonstrated significant shifts in the dominant species of microbiota under inflammatory conditions induced by DSS and evident restoration effect of FMT treatment on microbial composition. These faecal microbial alterations in FMT-treated rats led to a relative restoration of colon length, and a significant decrease in both epithelium damage and disease severity, which was reflected in lower serum pro-inflammatory cytokine levels. Haematological/biochemical parameters in DSS-treated animals showed signs of anaemia with a significant reduction in red blood cell count together with increasing levels of total bilirubin, creatinine and phosphorus suggesting potential protective effect of FMT. These results support FMT as a valuable therapeutic strategy to control inflammation during acute colitis.