Mucosal immune environment in colonic carcinogenesis: CD80 expression is associated to oxidative DNA damage and TLR4-NFκB signalling

Weak Cytotoxic T Cells Activation Predicts Low-Grade Dysplasia Persistence in Ulcerative Colitis

In patients with ulcerative colitis (UC), dysplasia develops in 10%–20% of cases. The persistence of low-grade dysplasia (LGD) in UC in 2 consecutive observations is still an indication for restorative proctocolectomy. Our hypothesis is that in the case of weak cytotoxic activation, dysplasia persists. We aimed to identify possible immunological markers of LGD presence and persistence.

Evaluating the expression level of co-stimulatory molecules CD 80 and CD 86 in different types of colon polyps

PURPOSE OF THE STUDY

Co-stimulatory molecules CD80 and CD86 are the members of B7 family, which stimulate the T lymphocytes in response to the malignant colon polyps. However, the expression of these molecules is depressed in cancers. In the present study, the transcription levels of CD80 and CD86 genes in the colon polyps (Precancerous lesions) and its association with the clinical features were examined.

PATIENTS AND METHODS

Forty-nine biopsies samples from patients with the colorectal polyps and 10 healthy subjects were collected by the colonoscopy. Questionnaires including clinical and demographic data were filled for all cases. Using Real-time PCR, the mucosal mRNA expression levels of CD80 and CD86 genes were quantified.

RESULTS

Adenoma and hyperplastic polyps were reported in 69.3 and 30.7 percent of 49 patients, respectively. Unlike hyperplastic polyps, the expression of CD86 was increased in adenoma polyps compared to controls (RQ=2.75 vs. 0.837, respectively). The data from CD80 showed noticeable reduction about 0.31 and 0.11 in adenoma and hyperplastic polyps, respectively, in response to control group (RQ=0.729). Also, analyzing colon and rectum polyps depicted a marked increment in CD86 level, in contrast to CD80.

CONCLUSION

Examining the mRNA expression levels of CD80 and CD86 genes between colon polyps with the rectal polyps shows that the enhanced level of CD86 in adenoma samples could be considered as a valuable biomarker for distinguishing the adenoma from hyperplastic polyps and the masses located in the colon from the rectum.

p53 expression in patients with ulcerative colitis - associated with dysplasia and carcinoma: a systematic meta-analysis

Background

Tumor suppressor gene p53 expression has been reported in patients with ulcerative colitis (UC). However, the correlation between p53 expression and UC remains controversial. The aim of this meta-analysis was to investigate the association between p53 expression and different pathological types of UC.

Methods

Publications were searched in the PubMed, Embase, EBSCO, Wangfang, and CNKI databases. The overall odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were summarized in this study.

Results

Final 19 papers were identified in this meta-analysis, including 1068 patients with UC and 130 normal tissue samples. Immunohistochemical p53 expression was significantly higher in UC without dysplasia and carcinoma (UC group) compared to normal tissue samples (OR = 3.14, P = 0.001), higher in UC with dysplasia than in UC group (OR = 10.76, P < 0.001), and higher in UC with colorectal cancer (CRC) than in UC with dysplasia (OR = 1.69, P = 0.035). Subgroup analysis of ethnicity (UC group vs. normal tissues) showed that p53 expression was correlated with UC in Asians, but not in Caucasians. When UC with dysplasia was compared to UC group, p53 expression was linked to UC with dysplasia among both Asians and Caucasians. When UC-CRC was compared to UC with dysplasia, p53 expression was not associated with UC-CRC in both Caucasians and Asians.

Conclusions

p53 expression was closely associated with UC-CRC development. p53 expression showed different ethnic characteristics among different pathological types of UC.

Electronic supplementary material

The online version of this article (10.1186/s12876-017-0665-y) contains supplementary material, which is available to authorized users.

Oxidative stress-induced mitochondrial dysfunction in a normal colon epithelial cell line

AIM

To determine how a normal human colon cell line reacts to microbial challenge as a way to study oxidative stress-induced responses associated with inflammatory bowel disease.

METHODS

Normal human colon epithelial cells (ATCC^® CRL.1790™) were stimulated with either heat killed E. coli or heat killed murine cecal contents (HKC) and examined for several relevant biomarkers associated with inflammation and oxidative stress including cytokine production, mitochondrial autophagy and oxidant status. TNFα, IL-1β and IL-8 protein concentrations were measured within the supernatants. Fluorescent microscopy was performed to quantify the production of reactive oxygen species (ROS) using an oxidation responsive fluorogenic probe. Mitochondrial morphology and mitochondrial membrane potential was assessed by dual staining using COXIV antibody and a dye concentrating in active mitochondria. Mitochondrial ROS scavenger was used to determine the source of ROS in stimulated cells. Autophagy was detected by staining for the presence of autophagic vesicles. Positive controls for autophagy and ROS/RNS experiments were treated with rapamycin and chloroquine. Mitochondrial morphology, ROS production and autophagy microscopy experiments were analyzed using a custom acquisition and analysis microscopy software (ImageJ).

RESULTS

Exposing CRL.1790 cells to microbial challenge stimulated cells to produce several relevant biomarkers associated with inflammation and oxidative stress. Heat killed cecal contents treatment induced a 10-12 fold increase in IL-8 production by CRL.1790 cells compared to unstimulated controls at 6 and 12 h (P < 0.001). Heat killed E. coli stimulation resulted in a 4-5 fold increase in IL-8 compared to the unstimulated control cells at each time point (P < 0.001). Both heat killed E. coli and HKC stimulated robust ROS production at 6 (P < 0.001), and 12 h (P < 0.01). Mitochondrial morphologic abnormalities were detected at 6 and 12 h based on reduced mitochondrial circularity and decreased mitochondrial membrane potential, P < 0.01. Microbial stimulation also induced significant autophagy at 6 and 12 h, P < 0.01. Lastly, blocking mitochondrial ROS generation using mitochondrial specific ROS scavenger reversed microbial challenge induced mitochondrial morphologic abnormalities and autophagy.

CONCLUSION

The findings from this study suggest that CRL.1790 cells may be a useful alternative to other colon cancer cell lines in studying the mechanisms of oxidative stress events associated with intestinal inflammatory disorders.

Mismatch repair gene defects in sporadic colorectal cancer enhance immune surveillance

Background

There is evidence that colorectal cancers (CRC) with DNA mismatch repair deficiency (MMR-D) are associated with a better prognosis than the generality of large bowel malignancies. Since an active immune surveillance process has been demonstrated to influence CRC outcome, we investigated whether MMR-D can enhance the immune response in CRC.

Patients and Methods

A group of 113 consecutive patients operated for CRC (42 stage I or II and 71 with stage III or IV) was retrospectively analyzed. The expression of MMR genes (MSH2, MLH1, MSH6 and PSM2) and co-stimulatory molecule CD80 was assessed by tissue microarray immunohistochemistry. In addition, tumor infiltrating mononuclear cells (TIMC) and T cell subpopulations (CD4, CD8, T-bet and FoxP-3) were quantified. The effect of specific siRNA (siMSH2, siMLH1, siMSH6 and siPSM2) transfection in HT29 on CD80 expression was quantified by flow cytometry. Non parametric statistics and survival analysis were used.

Results

Patients with MMR-D showed a higher T-bet/CD4 ratio (p = 0.02), a higher rate of CD80 expression and CD8 lymphocyte infiltration compared to those with no MMR-D. Moreover, in the MMR-D group, the Treg marker FoxP-3 was not expressed (p = 0.05). MMR-D patients with stage I or II and T-bet expression had a significant better survival (p = 0.009). Silencing of MSH2, MLH1 and MSH6, but not PSM2, significantly increased the rate of CD80+ HT29 cells (p = 0.007, p = 0.023 and p = 0.015, respectively).

Conclusions

CRC with MMR-D showed a higher CD80 expression, and CD8+ and Th1 T-cell infiltration. In vitro silencing of MSH2, MLH1 and MSH6 significantly increased CD80+ cell rate. These results suggest an enhanced immune surveillance mechanism in presence of MMR-D.

CD80-CD28 signaling controls the progression of inflammatory colorectal carcinogenesis

In patients with ulcerative colitis (UC) the cumulative risk of colon cancer is lower than the actual rate of dysplasia suggesting an efficient immune surveillance mechanism. Since the co-stimulatory molecule CD80 is overexpressed in dysplastic colonic mucosa of UC patients and T-cell activation entails effective costimulation, we aimed to evaluate the functional implication of CD80 signaling in colonic UC-associated carcinogenesis. In humans, we observed that the percentage of CD80+ and HLA-A+ IEC was increased in the dysplastic colonic mucosa of UC patients. In vitro, IEC activated CD8+ T-cells through a CD80-dependent pathway. Finally, in the AOM/DSS-induced colonic adenocarcinoma model CD80 signaling inhibition significantly increased the frequency and extension of high-grade dysplasia, whereas enhancing CD80 activity with an anti-CTLA4 antibody significantly decreased colonic dysplasia. In conclusion, CD80 signaling between IEC and T-cells represents a key factor controlling the progression from low to high grade dysplasia in inflammatory colonic carcinogenesis.

CD80 down-regulation is associated to aberrant DNA methylation in non-inflammatory colon carcinogenesis

Background

The lack of positive costimulatory molecules represents one of the mechanisms by which tumor cells evade immune surveillance. Promoter hypermethylation plays a major role in cancer development through transcriptional silencing of critical genes. The aim of this study was to examine the expression of the costimulatory molecule CD80 in relationship with genomic methylation in non-inflammatory colon carcinogenesis.

Methods

Colonic mucosal samples were collected from healthy subjects (n = 30) and from dysplastic adenoma (n = 14), and colon adenocarcinoma (n = 10). DNA methyltransferases-1, −3a, −3b and CD80 mRNA expression were quantified by real time qRT-PCR. The methylation status of CDH13, APC, MLH1, MGMT1 and RUNX3 gene promoters was assessed by methylation-specific PCR. CD80 expression was assessed in HT29, HCT-15 and LoVo cell lines after treatment with the DNA-methyltransferase inhibitor 5-Aza-2′-deoxycytidine.

Results

CD80 mRNA levels were significantly lower in the non-inflammatory dysplastic colonic mucosa of patients with one or more methylated genes and inversely correlated with patients’ methylation scores (τ = −0.41, p = 0.05 and τ = −0.37, p = 0.05, respectively). Treatment with 5-Aza-2′-deoxycytidine significantly increased CD80 expression both in terms of the level of CD80 mRNA (p = 0.007) and of CD80+ cells (p = 0.003).

Conclusions

These results indicate that the failure of immune surveillance mechanisms in non-inflammatory colon carcinogenesis may be linked to genomic methylation directly or indirectly affecting CD80 expression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2405-z) contains supplementary material, which is available to authorized users.

Inflammatory colonic carcinogenesis: A review on pathogenesis and immunosurveillance mechanisms in ulcerative colitis

Ulcerative colitis (UC) is characterized by repeated flare-ups of inflammation that can lead to oncogenic insults to the colonic epithelial. UC-associated carcinogenesis presents a different sequence of tumorigenic events compared to those that contribute to the development of sporadic colorectal cancer. In fact, in UC, the early events are represented by oxidative DNA damage and DNA methylation that can produce an inhibition of oncosuppressor genes, mutation of p53, aneuploidy, and microsatellite instability. Hypermethylation of tumor suppressor and DNA mismatch repair gene promoter regions is an epigenetic mechanism of gene silencing that contribute to tumorigenesis and may represent the first step in inflammatory carcinogenesis. Moreover, p53 is frequently mutated in the early stages of UC-associated cancer. Aneuploidy is an independent risk factor for forthcoming carcinogenesis in UC. Epithelial cell-T-cell cross-talk mediated by CD80 is a key factor in controlling the progression from low to high grade dysplasia in UC-associated carcinogenesis.

Oxidative stress and mitochondrial dysfunction across broad-ranging pathologies: toward mitochondria-targeted clinical strategies

Beyond the disorders recognized as mitochondrial diseases, abnormalities in function and/or ultrastructure of mitochondria have been reported in several unrelated pathologies. These encompass ageing, malformations, and a number of genetic or acquired diseases, as diabetes and cardiologic, haematologic, organ-specific (e.g., eye or liver), neurologic and psychiatric, autoimmune, and dermatologic disorders. The mechanistic grounds for mitochondrial dysfunction (MDF) along with the occurrence of oxidative stress (OS) have been investigated within the pathogenesis of individual disorders or in groups of interrelated disorders. We attempt to review broad-ranging pathologies that involve mitochondrial-specific deficiencies or rely on cytosol-derived prooxidant states or on autoimmune-induced mitochondrial damage. The established knowledge in these subjects warrants studies aimed at elucidating several open questions that are highlighted in the present review. The relevance of OS and MDF in different pathologies may establish the grounds for chemoprevention trials aimed at compensating OS/MDF by means of antioxidants and mitochondrial nutrients.