Relationship between differantiation of colon polyps and expression of vitamin D receptor (VDR) on T lymphocyte and NK cells

Colon cancers are the first type of cancers that are related to vitamin D deficiency. In previous studies, it has been shown that vitamin D has regulatory functions on the pathways of development of colon carcinoma, and there may be defects on these pathways when there is low levels of vitamin in patients. Besides that, there are studies which indicate that vitamin D is also a modulator for T lymphocyte and NK cell functions. The aim of this study is determination of the relationship between serum levels of active and inactive vitamin D3 levels, expression rate and intensity of VDR on T lymphocytes and NK cells, and type and level of dysplasia of these pre-malignant lesions, and the potential benefits of vitamin D replacement therapy in these patients. We included 45 patient into the study, with an age over 18 years, and in whom colonoscopy was indicated and had polypectomy. The procedure was performed at the endoscopy unit of the hospital of Akdeniz University, Faculty of Medicine. We excluded patients who had a history of colon cancer , who used any kind of immune-modulator therapy in the late 6 months, who had any auto-immune disease and had active infection at the time of the procedure. Patients who were included into the study were divided into four groups according to their polyp type and two groups according to level of dysplasia which were reported by the same pathologist at the pathology department. We obtained informed consent forms from patients who accepted to participate in the study. Serum samples were evaluated for VDR expression rate and intensity of T and NK cells. Identification of T lymphocytes and NK cells, and their VDR expession rate(%) and intensity (MFI) were evaluated with flow cytometry at Hospital of Akdeniz University, Research Laboratory of Transplantation. CD3, CD4, CD8, CD14, CD 56 and VDR antibodies were used for this evaluation. We used ELISA technique for active and inactive vitamin D3 level detection. In the 45 patients who were included into the study, 8 had hyperplastic polyp, 15 had tubulovillous adenoma, 10 had tubulovillous adenoma and 12 had villous adenoma. After all the analyses were performed, we reached the conclusion that when the groups were compared according to the type of polyps, there was not a significant difference in terms of the rate of expression and intensity of VDR on T and NK cells. (p>0,05) There wasn't a significant relation between groups for active and inactive vitamin D3 levels. (p>0,05) In the evaluation according to the degree of dysplasia, it was found that there was a significant difference in the ratio of VDR+ CD8+ T lymphocyte to CD8+ T lymphocyte population (p=0,018) There wasn't a statistically significant difference between active and inactive vitamin D levels and level of dysplasia in between the groups There are a lot of factors which determine the fate of colon adenomas on the adenoma-carcinoma sequence. Previous studies revealed that vitamin D and vitamin D receptor are also considered among these factors. Vitamin D has also a modulator role on the functions of T lymphocytes and NK cells, which are part of the immun system and have anti-tumor activities. In this study, we aimed to find a relationship between adenoma differentiation and VDR expression rate and the intensity of VDR onT lymphocytes and NK cells, and also serum levels of active and inactive vitamin D3. We didn't find any relationship between test parameters except the level of dysplasia and the ratio of VDR+ CD8+ T lymphocytes to total CD8+ T lymphocytes. We think that the main limiting factor in our study was the small number of samples. We believe that there maybe more significant results with a higher number of samples.