Obesity exacerbates colitis-associated cancer via IL-6-regulated macrophage polarisation and CCL-20/CCR-6-mediated lymphocyte recruitment

CCL20 mediates the anti-tumor effect of vitamin D3 in p38MAPK/NF-κB signaling in colitis-associated carcinogenesis

Vitamin D3 is beneficial in ameliorating or preventing inflammation and carcinogenesis. CCL20 is a potential therapeutic target in carcinogenesis, which mediates the protective effect of vitamin D or vitamin D analogue in autoimmune and cancer diseases. Here we aim to evaluate whether vitamin D3 plays a protective role in colitis-associated colorectal cancer (CAC) by affecting CCL20 and the molecular mechanism. Administration of azoxymethane (AOM) followed with dextran sulfate sodium (DSS) was used to simulate CAC in mouse. After 5-day DSS treatment, vitamin D3 supplementation was for 9 weeks at 60 IU/g/w. We found that dietary vitamin D3 significantly reduced the tumor number and tumor burden in mouse. In-vivo and -vitro, vitamin D3 reduced the levels of CCL20, phospho-p38 MAPK (p-p38) and phospho-NF-κB p65 (p-p65), and the transcriptional activity of NF-κB. Further studies showed that CCL20 mediated the inhibition of vitamin D3 in p38MAPK-mediated NF-κB signaling in vitro. Taken together, vitamin D3 effectively suppressed colonic carcinogenesis in AOM-DSS mouse model. Downregulation of CCL20 may contribute to the preventive effect of vitamin D3 on NF-κB activity. It may merit further clinical investigation as a therapeutic agent against CAC in humans.

Chaperone-mediated autophagy regulates apoptosis and the proliferation of colon carcinoma cells

Chaperone-mediated autophagy (CMA) is one of the three types of autophagy. In recent years, CMA has been shown to be associated with the pathogenesis of several types of cancer. However, whether CMA is involved in the pathogenesis of colorectal cancer (CRC) remains unclear. In this study, we investigated CMA activity in tissue specimens from CRC patients and mouse models of colitis-associated CRC (induced by administration of AOM plus DSS). In addition, we down-regulated CMA in CT26 colon carcinoma cells stably transfected with a vector expressing a siRNA targeting LAMP-2A, the limiting component in the CMA pathway, to explore the role of CMA in these cells. Apoptosis was detected using TUNEL assay, and the apoptosis-related proteins were detected using western blotting. Cell proliferation was assessed using MTT assay, Ki-67 labelling and western blotting for PCNA. We found that LAMP-2A expression was significantly increased in CRC patients and mouse models and varied according to the stage of the disease. Inhibition of CMA in CT26 cells facilitated apoptosis, as evidenced by increased TUNEL immunolabeling, increased expression of Bax and Bnip3, and decreased expression of Bcl-2. Cell proliferation assays showed that inhibition of CMA impeded the proliferation of CT26 cells. These data support the hypothesis that CMA is up-regulated in CRC, and inhibition of CMA may be a new therapeutic strategy for CRC patients.

The Role of Adaptor Protein CARD9 in Colitis-Associated Cancer

The adaptor protein CARD9 plays an important role in anti-fungal immunity responses, linking detection of fungi by surface receptors to activation of the transcription factor nuclear factor κB (NF-κB). Recent studies indicate that CARD9 also plays different but vital roles during the development of colitis-associated colorectal cancer (CAC). This review summarizes the current understanding of CARD9 functions in CAC, and we discuss its potentially carcinogenic mechanisms.

Tissue Immune Cells Fuel Obesity-Associated Inflammation in Adipose Tissue and Beyond

Obesity-associated inflammation stems from a combination of cell-intrinsic changes of individual immune cell subsets and the dynamic crosstalk amongst a broad array of immune cells. Although much of the focus of immune cell contributions to metabolic disease has focused on adipose tissue-associated cells, these potent sources of inflammation inhabit other metabolic regulatory tissues, including liver and gut, and recirculate to promote systemic inflammation and thus obesity comorbidities. Tissue-associated immune cells, especially T cell subpopulations, have become a hotspot of inquiry based on their contributions to obesity, type 2 diabetes, non-alcoholic fatty liver diseases and certain types of cancers. The cell-cell interactions that take place under the stress of obesity are mediated by intracellular contact and cytokine production, and constitute a complicated network that drives the phenotypic alterations of immune cells and perpetuates a feed-forward loop of metabolic decline. Herein we discuss immune cell functions in various tissues and obesity-associated cancers from the viewpoint of inflammation. We also emphasize recent advances in the understanding of crosstalk amongst immune cell subsets under obese conditions, and suggest future directions for focused investigations with clinical relevance.

L. plantarum, L. fermentum, and B. breve Beads Modified the Intestinal Microbiota and Alleviated the Inflammatory Response in High-Fat Diet-Fed Mice

This paper aims to study the effects of compound microbe-based beads on changes in the intestinal microbiota and alleviation of high-fat (HF) diet-induced inflammatory responses. Forty-eight mice were fed base chow or a high-fat diet for 4 weeks and then randomly separated into six groups: normal diet (group A), high-fat diet (group B), high-fat positive control (fed with high-fat chow plus Tetrahydrolipstatin, group C), high-fat chow plus B. breve beads (group D), high-fat chow plus L. plantarum-L. fermentum beads (group E), and high-fat chow plus L. plantarum-L. fermentum-B. breve beads (group F). The body weights were measured. The serum cytokine and lipid levels were determined by ELISA, and high-throughput sequence analysis of the fecal microbiota was conducted. Beads with cell encapsulation rates higher than 99% decreased the body weight from 50.97 ± 3.44 g in group B to 42.64 ± 2.63 g in group F at the end of the experiment (p = 0.00019). The total cholesterol content in group F was 80.14 ± 9.37 mmol/L, which was significantly lower than that in group A (96.13 ± 24.07 mmol/L) (p = 0.02765), group B (102.52 ± 12.20 mmol/L) (p = 0.00196), and group C (98.99 ± 11.32 mmol/L) (p = 0.00804). In addition, the serum IL-6 level showed no significant difference between group F and the base chow control group. The microbial cell-loaded bead intervention led to increased abundances of Bifidobacterium and Lactobacillus in mouse feces. Oral administration of three strain-based beads led to alleviation of inflammatory reactions in high-fat diet-fed mice.

Fbxw7 increases CCL2/7 in CX3CR1hi macrophages to promote intestinal inflammation

Resident and inflammatory mononuclear phagocytes (MPh) with functional plasticity in the intestine are critically involved in the pathology of Inflammatory Bowel Diseases (IBD), in which the mechanism remains incompletely understood. In the present study, we found that increased expression of E3 ligase FBXW7 in the inflamed intestine was significantly correlated to IBD severity in both human diseases and mice model. Myeloid-Fbxw7 deficiency protected mice from dextran sodium sulfate (DSS) and 2,6,4-trinitrobenzene sulfonic acid (TNBS) induced colitis. Fbxw7 deficiency resulted in decreased production of chemokines CCL2 and CCL7 by colonic CX3CR1hi resident macrophages and reduced accumulation of CX3CR1int pro-inflammatory MPh in colitis colon tissue. Mice received AAV-shFbxw7 administration showed significantly improved survival rate and alleviated colitis. Mechanisms screening demonstrated that FBXW7 suppresses H3K27me3 modification and promotes Ccl2 and Ccl7 expression via degradation of histone-lysine N-methyltransferase EZH2 in macrophages. Taken together, our results indicate that FBXW7 degrades EZH2 and increases Ccl2/Ccl7 in CX3CR1hi macrophages, which promotes the recruiting CX3CR1int pro-inflammatory MPh into local colon tissues with colitis. Targeting FBXW7 might represent a potential therapeutic approach for intestine inflammation intervention.

Intestinal insulin/IGF1 signalling through FoxO1 regulates epithelial integrity and susceptibility to colon cancer

Obesity promotes the development of insulin resistance and increases the incidence of colitis-associated cancer (CAC), but whether a blunted insulin action specifically in intestinal epithelial cells (IECs) affects CAC is unknown. Here, we show that obesity impairs insulin sensitivity in IECs and that mice with IEC-specific inactivation of the insulin and IGF1 receptors exhibit enhanced CAC development as a consequence of impaired restoration of gut barrier function. Blunted insulin signalling retains the transcription factor FOXO1 in the nucleus to inhibit expression of Dsc3, thereby impairing desmosome formation and epithelial integrity. Both IEC-specific nuclear FoxO1ADA expression and IEC-specific Dsc3 inactivation recapitulate the impaired intestinal integrity and increased CAC burden. Spontaneous colonic tumour formation and compromised intestinal integrity are also observed upon IEC-specific coexpression of FoxO1ADA and a stable Myc variant, thus suggesting a molecular mechanism through which impaired insulin action and nuclear FOXO1 in IECs promotes CAC.

Glutamine Metabolism in Macrophages: A Novel Target for Obesity/Type 2 Diabetes

Obesity is a nutritional disorder resulting from a chronic imbalance between energy intake and expenditure. This disease is characterized by inflammation in multiple cell types, including macrophages. M1 macrophage responses are correlated with the progression of obesity or diabetes; therefore, strategies that induce repolarization of macrophages from an M1 to an M2 phenotype may be promising for the prevention of obesity- or diabetes-associated pathology. Glutamine (the most abundant amino acid in the plasma of humans and many other mammals including rats) is effective in inducing polarization of M2 macrophages through the glutamine-UDP-N-acetylglucosamine pathway and α-ketoglutarate produced via glutaminolysis, whereas succinate synthesized via glutamine-dependent anerplerosis or the γ-aminobutyric acid shunt promotes polarization of M1 macrophages. Interestingly, patients with obesity or diabetes show altered glutamine metabolism, including decreases in glutamine and α-ketoglutarate concentrations in serum but increases in succinate concentrations. Thus, manipulation of macrophage polarization through glutamine metabolism may provide a potential target for prevention of obesity- or diabetes-associated pathology.

Targeting regulation of tryptophan metabolism for colorectal cancer therapy: a systematic review

Colorectal cancer (CRC) is one of the most malignant cancers resulting from abnormal metabolism alterations. As one of the essential amino acids, tryptophan has a variety of physiological functions, closely related to regulation of immune system, central nervous system, gastrointestinal nervous system and intestinal microflora. Colorectal cancer, a type of high-grade malignancy disease, stems from a variety of factors and often accompanies inflammatory reactions, dysbacteriosis, and metabolic disorders. Colorectal cancer accompanies inflammation and imbalance of intestinal microbiota and affects tryptophan metabolism. It is known that metabolites, rate-limiting enzymes, and ARH in tryptophan metabolism are associated with the development of CRC. Specifically, IDO1 may be a potential therapeutic target in colorectal cancer treatment. Furthermore, the reduction of tryptophan amount is proportional to the poor quality of life for colorectal cancer patients. This paper aims to discuss the role of tryptophan metabolism in a normal organism and investigate the relationship between this amino acid and colorectal cancer. This study is expected to provide theoretical support for research related to targeted therapy for colorectal cancer. Furthermore, strategies that modify tryptophan metabolism, effectively inhibiting tumor progression, may be more effective for CRC treatment.

Colorectal cancer (CRC) is one of the most malignant cancers resulting from abnormal metabolism alterations.

Obesity-Induced TNFα and IL-6 Signaling: The Missing Link between Obesity and Inflammation-Driven Liver and Colorectal Cancers

Obesity promotes the development of numerous cancers, such as liver and colorectal cancers, which is at least partly due to obesity-induced, chronic, low-grade inflammation. In particular, the recruitment and activation of immune cell subsets in the white adipose tissue systemically increase proinflammatory cytokines, such as tumor necrosis factor α (TNFα) and interleukin-6 (IL-6). These proinflammatory cytokines not only impair insulin action in metabolic tissues, but also favor cancer development. Here, we review the current state of knowledge on how obesity affects inflammatory TNFα and IL-6 signaling in hepatocellular carcinoma and colorectal cancers.

CCR6–CCL20 Axis in IBD: What Have We Learnt in the Last 20 Years?

CC chemokine receptor 6 (CCR6) and its specific partner CC chemokine ligand 20 (CCL20) are known to play a pivotal role in intestinal inflammation. CCR6-associated inflammatory bowel disease (IBD) is already at the forefront of experimental inflammatory disease models, being the subject of numerous analytical studies. IBD is associated with two sub phenotypes, Crohn’s disease (CD) and ulcerative colitis (UC). Both these disease entities produce potent immune dysregulation followed by intense tissue damage within the gut mucosal system, initiating symptoms that are severely debilitating. Multiple causative factors are said to be responsible for IBD, but direct immune dysfunction is kindled by overplay of innate and adaptive immune responses produced against the luminal contents through the weakened or leaky gut epithelial barrier. Once immune homeostasis is not achieved by endogenous protective mechanisms, the self-assertive adaptive immunity mobilizes its various T and B cell cohorts, initializing their immune mechanisms by deploying the immune cells towards the site of infection. CCR6 and its unique solitary ligand CCL20 are small protein molecules that are abundantly expressed by T and B lymphocytes and act as chemotactic immune-modulatory envoys that help in the deployment of the effector lymphocyte arm of the immune system and produce two directly opposing outcomes in IBD. This dichotomous immunity consists of either immune tolerance or inflammation which then develops into a chronic state, remaining unresponsive to inherent immunity or targeted clinical therapy. In this review, we have identified large numbers of experimental studies that have employed both mouse models and clinical subjects spanning a period of nearly two decades and we have clustered these into 13 different groups. This review will provide greater understanding of the CCR6–CCL20 axis in IBD and identify gaps in the literature that can be filled in the future.