Can chymase-positive mast cells play a role in the progression of gastric cancer via angiogenesis?

Measuring human mast cell-mediated cytotoxicity against human tumour cells: three-colour flow cytometry using monoclonal antibody target staining with annexin V / propidium iodide co-labelling of death

BACKGROUND

Chromium release assay is the standard method for evaluation of cell-mediated cytotoxicity, including that of mast cells. Although this is a reproducible method, it has more drawbacks than even radioactivity. In addition to the shortcoming of measuring only necrotic killing, some non-radioactive methods have not been widely used either. The numerous limitations of these methods led researchers to develop other techniques. This study describes a new flow cytometric approach that measures human mast cell-mediated cytotoxicity by marking target cells with monoclonal antibody alongside annexin V/ PI co-labelling.

METHODS

A colony forming unit - mast in vitro was developed from human bone marrow mononuclear cells in serum-free methylcellulose medium. Six-week-old human bone marrow-derived mast cells were used as effectors, and malignant B-lymphoblastoid cell lines like Daudi / Raji cells as targets. Effectors and targets were both co-incubated for short and long-term durations, and experiments were repeated several times. Cytotoxicity was calculated by flow cytometric mast cell-mediated cytotoxicity assay.

RESULTS

This method was able to clearly show mast cell-mediated cytotoxicity against human tumours. It is well-known that some lymphokine-activated killer-sensitive cells are resistant to mast cell-mediated cytotoxicity. However, a different type of lymphokine activated killer-sensitive cell in this study was found to be very sensitive to mast cell-mediated cytotoxicity. Moreover, this technique also allowed us to separate killing into different stages: early and late apoptosis.

CONCLUSIONS

When compared to chromium release and non-radioactive methods, this method has the advantages of allowing evaluation of early apoptosis and short/long term mast cell-mediated cytotoxicity with specific target marking.

Effects of myenteric denervation on extracellular matrix fibers and mast cell distribution in normal stomach and gastric lesions

BACKGROUND

In this study the effect of myenteric denervation induced by benzalconium chloride (BAC) on distribution of fibrillar components of extracellular matrix (ECM) and inflammatory cells was investigated in gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Rats were divided in four experimental groups: non-denervated (I) and denervated stomach (II) without MNNG treatment; non-denervated (III) and denervated stomachs (IV) treated with MNNG. For histopathological, histochemical and stereological analysis, sections of gastric fragments were stained with Hematoxylin-Eosin, Picrosirius-Hematoxylin, Gomori reticulin, Weigert's Resorcin-Fuchsin, Toluidine Blue and Alcian-Blue/Safranin (AB-SAF).

RESULTS

BAC denervation causes an increase in the frequency of reticular and elastic fibers in the denervated (group II) compared to the non-denervated stomachs (group I). The treatment of the animals with MNNG induced the development of adenocarcinomas in non-denervated and denervated stomachs (groups III and IV, respectively) with a notable increase in the relative volume of the stroma, the frequency of reticular fibers and the inflammatory infiltrate that was more intense in group IV. An increase in the frequency of elastic fibers was observed in adenocarcinomas of denervated (group IV) compared to the non-denervated stomachs (group III) that showed degradation of these fibers. The development of lesions (groups III and IV) was also associated with an increase in the mast cell population, especially AB and AB-SAF positives, the latter mainly in the denervated group IV.

CONCLUSIONS

The results show a strong association in the morphological alteration of the ECM fibrillar components, the increased density of mast cells and the development of tumors induced by MNNG in the non-denervated rat stomach or denervated by BAC. This suggests that the study of extracellular and intracellular components of tumor microenvironment contributes to understanding of tumor biology by action of myenteric denervation.