Quantitative analysis of mast cells in benign and malignant colonic lesions: immunohistochemical study on formalin-fixed, paraffin-embedded tissues

Prolonged inhibition of intratumoral mast cells enhances efficacy of low-dose antiangiogenic therapy

Low-dose antiangiogenic therapies have demonstrated the ability to enhance normalization of tumor vessels, consequently improving hypoxia levels, drug delivery, and promoting anticancer immune responses. Mast cells have been identified as contributors to resistance against antiangiogenic therapy and facilitators of abnormal neoangiogenesis. In this study, we demonstrate that by simultaneously targeting intratumoral mast cells with Imatinib and administering low-dose anti-VEGFR2 therapy, antitumor efficacy can be enhanced in preclinical models. Thus, combinatory treatment overcomes therapy resistance, while concurrently promoting tumor vessel normalization. Notably, histomorphometric analysis of tumor sections revealed that vessel perfusion could be improved through mast cell inhibition and, despite a significantly reduced microvessel density, the combination treatment did not result in elevated tumor hypoxia levels compared to anti-VEGFR2 therapy alone. Short-term Imatinib application effectively increased antitumor efficacy, and by prolonging the application of Imatinib tumor vessel normalization was additionally improved. The combination of mast cell depletion and antiangiogenic treatments has not been investigated in detail and promises to help overcoming therapy resistance. Further studies will be required to explore their impact on other treatment approaches, and subsequently to validate these findings in a clinical setting.

Prostaglandin E2 in the Tumor Microenvironment, a Convoluted Affair Mediated by EP Receptors 2 and 4

The involvement of the prostaglandin E2 (PGE2) system in cancer progression has long been recognized. PGE2 functions as an autocrine and paracrine signaling molecule with pleiotropic effects in the human body. High levels of intratumoral PGE2 and overexpression of the key metabolic enzymes of PGE2 have been observed and suggested to contribute to tumor progression. This has been claimed for different types of solid tumors, including, but not limited to, lung, breast, and colon cancer. PGE2 has direct effects on tumor cells and angiogenesis that are known to promote tumor development. However, one of the main mechanisms behind PGE2 driving cancerogenesis is currently thought to be anchored in suppressed antitumor immunity, thus providing possible therapeutic targets to be used in cancer immunotherapies. EP2 and EP4, two receptors for PGE2, are emerging as being the most relevant for this purpose. This review aims to summarize the known roles of PGE2 in the immune system and its functions within the tumor microenvironment. SIGNIFICANCE STATEMENT: Prostaglandin E2 (PGE2) has long been known to be a signaling molecule in cancer. Its presence in tumors has been repeatedly associated with disease progression. Elucidation of its effects on immunological components of the tumor microenvironment has highlighted the potential of PGE2 receptor antagonists in cancer treatment, particularly in combination with immune checkpoint inhibitor therapeutics. Adjuvant treatment could increase the response rates and the efficacy of immune-based therapies.

Role of prostanoids in gastrointestinal cancer

Chronic inflammation is a risk factor for gastrointestinal cancer and other diseases. Most studies have focused on cytokines and chemokines as mediators connecting chronic inflammation to cancer, whereas the involvement of lipid mediators, including prostanoids, has not been extensively investigated. Prostanoids are among the earliest signaling molecules released in response to inflammation. Multiple lines of evidence suggest that prostanoids are involved in gastrointestinal cancer. In this Review, we discuss how prostanoids impact gastrointestinal cancer development. In particular, we highlight recent advances in our understanding of how prostaglandin E2 induces the immunosuppressive microenvironment in gastrointestinal cancers.

CCR5 expression in inflammatory bowel disease and its correlation with inflammatory cells and β-arrestin2 expression

OBJECTIVE

To elucidate the correlation of expression of CC chemokine receptor 5 (CCR5) with degrees of inflammatory cells infiltration and expression of β-arrestin2 in biopsic intestinal mucosa of the patients with inflammatory bowel disease (IBD).

METHODS

Paraffin sections were derived from 53 patients with active IBD, 26 patients with remissive IBD and 30 healthy people. Immunohistochemical envision two-step method was used to test the expression of CCR5 and β-arrestin2 in biopsic intestinal mucosa. HE and toluidine blue staining were used to detect the pathological cytological analysis and classification in lamina propria of colonic mucosa.

RESULTS

The positive rate, strong positive rate and immunohistochemical score of CCR5 expression in active IBD were significantly higher than that in normal controls and remissive IBD (p < .05). CCR5 expression had no obvious correlation with clinical severity, lesion distribution and endoscopic classification of active IBD. Neutrophils, eosinophils and lymphocytes in active IBD were significantly higher than that in normal controls and remissive IBD (p < .05), while the lymphocyte grade had a positive correlation with CCR5 expression (p = .042, r = .286). Mastocytes in active IBD, remissive IBD and normal controls had no obvious difference (p > .05). β-arrestin2 expression was significantly lower in active IBD than that in remissive IBD and normal controls, and it had a negative correlation with CCR5 expression (p = .01, r = -.247).

CONCLUSIONS

CCR5 is highly expressed in active IBD, and it has positive correlation with lymphocyte grade and negative correlation with expression of β-arrestin2.

An inflammatory mediator, prostaglandin E2, in colorectal cancer

It is widely accepted that intake of dietary fats and chronic inflammation are risk factors for developing colorectal cancer. Arachidonic acid is a major component of animal fats, and the bioactive lipids produced from this substrate play critical roles in a variety of biologic processes, including cancer. Cyclooxygenase-derived prostaglandin E2 is a known proinflammatory lipid mediator that promotes tumor progression. Metabolism of arachidonic acid by the cyclooxygenase pathway provides one mechanism for the contribution of dietary fats and chronic inflammation to carcinogenesis. In this review, we highlight recent advances in our understanding of how a proinflammatory mediator prostaglandin E2 promotes colorectal cancer immune evasion. These findings may provide a rationale for the development of new therapeutic approaches to subvert tumor-induced immunosuppression.

Possible biological and translational significance of mast cells density in colorectal cancer

Mast cells (MCs), located ubiquitously near blood vessels, are descended from CD34⁺ hematopoietic stem cells. Initially, although their role has been well defined in hypersensitivity reactions, the discovery of their sharing in both innate and adaptive immunity has allowed to redefine their crucial interplay on the regulatory function between inflammatory and tumor cells through the release of mediators granule-associated (mainly tryptase and vascular endothelial growth factor). In particular, in several animal and human malignancies it has been well demonstrated that activated c-Kit receptor (c-KitR) and tryptase (an agonist of the proteinase-activated receptor-2) take pivotal part in tumor angiogenesis after the MCs activation, contributing to tumor cells invasion and metastasis. In this review, we focused on crucial MCs density (MCD) role in colorectal cancer (CRC) development and progression angiogenesis-mediated; then, we will analyze the principal studies that have focused on MCD as possible prognostic factor. Finally, we will consider a possible role of MCD as novel therapeutic target mainly by c-KitR tyrosine kinase inhibitors (imatinib, masitinib) and tryptase inhibitors (gabexate and nafamostat mesylate) with the aim to prevent CRC progression.

Mast cells and eosinophils are involved in activation of ulcerative colitis

PURPOSE

The intestinal mucosal immune cells such as the mast cells and eosinophils play an important role in the pathogenesis of ulcerative colitis (UC). The aim of present study was to compare the number of mast cells and eosinophils in patients with active and non-active ulcerative colitis. Another purpose was to found whether the number of eosinophils could correlate with number of mast cells in both tested groups.

MATERIAL AND METHODS

The twenty-five of formalin-fixed, paraffin-embedded tissue specimens of active ulcerative colitis, the twenty of non-active ulcerative colitis and the ten of controls were retrieved from archival material. Tryptase and chymase immunopositive cells were detected using immunohistochemical method. Additionally, the number of mast cells and eosinophils were detected using the most common histochemical methods.

RESULTS

The number of eosinophils and toluidine blue stained and tryptase immunopositive mast cells was significantly increased in active UC compared to non-active UC. In active stage of UC positive correlation between the number of mast cells stained with toluidine blue and the number of chymase and tryptase immunopositive mast cells were observed. Moreover, the number of eosinophils was significantly correlated with number of mast cells stained with toluidine blue and number of tryptase- and chymase immunopositive mast cells. In non-active stage of UC positive correlation was observed only between the number of mast cells stained with toluidine blue and chymase immunopositive cells and eosinophils.

CONCLUSIONS

In conclusion, our findings confirmed that mast cells and eosinophils are functionally involved in the course of UC.

Accumulation of Mast Cells in the Lesions and Effects of Antiallergic Drugs on the Patients with Inflammatory Bowel Disease

The pathomechanism of inflammatory bowel disease (IBD) has not yet been fully demonstrated. However, it is well known that mast cells are present in the gastrointestinal tract, suggesting that mast cells may take part in it. So, we investigated the number of mast cells in IBD, such as ulcerative colitis (UC) and eosinophilic colitis, and showed that the number of mast cells was increased in the inflammatory lesions. We also presented a case of UC which was treated successfully with an antiallergic drug, tranilast. Furthermore, possible new approaches to treating the disease with immunomodulators including suplatast are introduced. However, our investigations were performed with a limited number of patients with IBD, and additional further studies are required to confirm the findings.

Mast Cells in Adjacent Normal Colon Mucosa rather than Those in Invasive Margin are Related to Progression of Colon Cancer

OBJECTIVE

Mast cells (MC) reside in the mucosa of the digestive tract as the first line against bacteria and toxins. Clinical evidence has implied that the infiltration of mast cells in colorectal cancers is related to malignant phenotypes and a poor prognosis. This study compared the role of mast cells in adjacent normal colon mucosa and in the invasive margin during the progression of colon cancer.

METHODS

Specimens were obtained from 39 patients with colon adenomas and 155 patients with colon cancers treated at the Sun Yat-sen University Cancer Center between January 1999 and July 2004. The density of mast cells was scored by an immunohistochemical assay. The pattern of mast cell distribution and its relationship with clinicopathologic parameters and 5-year survival were analyzed.

RESULTS

The majority of mast cells were located in the adjacent normal colon mucosa, followed by the invasive margin and least in the cancer stroma. Mast cell count in adjacent normal colon mucosa (MCC(adjacent)) was associated with pathologic classification, distant metastases and hepatic metastases, although it was not a prognostic factor. In contrast, mast cell count in the invasive margin (MCC(invasive)) was associated with neither the clinicopathlogic parameters nor overall survival.

CONCLUSION

Mast cells in the adjacent normal colon mucosa were related to the progression of colon cancer, suggesting that mast cells might modulate tumor progression via a long-distance mechanism.

Effect of royal jelly on experimental colitis Induced by acetic acid and alteration of mast cell distribution in the colon of rats

This study investigated the effects of royal jelly (RJ) on acetic acid-induced colitis in rats. Twenty adult female Wistar albino rats were divided into four treatment groups of 5 animals each, including a control group (Group I); Group II was treated orally with RJ (150 mg kg(-1) body weight); Group III had acetic acid-induced colitis; and Group IV had acetic acid-induced colitis treated orally with RJ (150 mg kg(-1) body weight) for 4 weeks. Colitis was induced by intracolonic instillation of 4% acetic acid; the control group received physiological saline (10 mL kg(-1)). Colon samples were obtained under deep anaesthesia from animals in all groups. Tissues were fixed in 10% formalin neutral buffer solution for 24 h and embedded in paraffin. Six-micrometre-thick sections were stained with Mallory’s triple stain and toluidine blue in 1% aqueous solution at pH 1.0 for 5 min (for Mast Cells). RJ was shown to protect the colonic mucosa against the injurious effect of acetic acid. Colitis (colonic damage) was confirmed histomorphometrically as significant increases in the number of mast cells (MC) and colonic erosions in rats with acetic acid-induced colitis. The RJ treatment significantly decreased the number of MC and reduced the area of colonic erosion in the colon of RJ-treated rats compared with rats with untreated colitis. The results suggest that oral treatment with RJ could be used to treat colitis.

The tumor microenvironment in colorectal carcinogenesis

Colorectal cancer is the second leading cause of cancer-related mortality in the United States. Therapeutic developments in the past decade have extended life expectancy in patients with metastatic disease. However, metastatic colorectal cancers remain incurable. Numerous agents that were demonstrated to have significant antitumor activity in experimental models translated into disappointing results in extending patient survival. This has resulted in more attention being focused on the contribution of tumor microenvironment to the progression of a number of solid tumors including colorectal cancer. A more complete understanding of interactions between tumor epithelial cells and their stromal elements will enhance therapeutic options and improve clinical outcome. Here we will review the role of various stromal components in colorectal carcinogenesis and discuss the potential of targeting these components for the development of future therapeutic agents.