The role of vitamin D and the vitamin D receptor levels in development ofchronic rejection in kidney transplant recipients

There are a number of studies that suggest that graft survival is prolonged and vitamin D is a protective effect on kidney function. Purpose of our work is to assess whether serum vitamin D level and vitamin D receptor level in immunocytes are related with development of chronic rejection in renal transplant recipients or not. A total of 42 renal transplantation groups were enrolled in the Medical Faculty of Akdeniz University Hospital during the last 16 years and were followed up at the 2013-2014 kidney transplant polyclinic and at least 3 months after transplantation and older than 18 years. Twenty - five patients who were diagnosed as chronic rejection with renal biopsy were enrolled in the chronic rejection arm. Seventeen kidney functions are stable; renal functions were taken to the stabilized branch. 28 volunteers, aged 18 years or older, who did not have a known systemic disease that referred to internal medicine polyclinics and did not take D vitamins and analogs, were volunteered to work as a healthy control group. We received serum samples from the healthy control, chronic rejection group, the patient control group and 25 (OH) D3 vitamins, 1,25 (OH) 2D3 vitamins and VDR fractions in CD4+, CD8+, CD14+, CD56+ cells were measured. PTH levels, calcium and phosphorus levels of the patients were reached and recorded from Miamed, the computer registry system of the hospital in the period when the patient's serum samples were taken. There was no statistically significant difference in demographic characteristics such as age and sex in 3 groups. There was a statistically significant difference in the percentage of VDR in CD4+ cells of 3 groups, including chronic rejection group, patient control group and healthy control group (p <0,05). The percentage of VDR in CD4+ cells is higher in the healthy control group than in the patient control group, and higher in the patient control group than in the chronic rejection group. There was no statistically significant difference (p= 0.076) when the percentage of VDR in CD8+ cells of 3 groups, including chronic rejection group, patient control group and healthy control group, was compared. The percentage of VDR in CD8+ cells is higher in the healthy control group than in the patient control group, and higher in the patient control group than in the chronic rejection group. There was no statistically significant difference in the percentage of VDR in CD14+ cells in 3 groups, including chronic rejection group, patient control group and healthy control group (p> 0,05). The percentage of VDR in CD14+ cells was higher in the patient control group than in the chronic rejection group. There was a statistically significant difference in VDR percentage in CD56+ cells of 3 groups, including chronic rejection group, patient control group and healthy control group (p <0,05). The percentage of VDR in CD56+ cells was higher in the patient control group than in the chronic rejection group. In the chronic rejection group, according to the patient control group, inactive D vitamins, active D vitamine levels and the percentage of VDR in all immun cells is lower. In the chronic rejection group, according to the patient control group, PTH levels are much higher. As a result, incompressible PTH enhances the synthesis of FGF-23. FGF-23 increases the catabolism of vitamin D and inhibits the enzyme 1-alpha hydroxylase. The reason for the lower VDR percentage in the chronic rejection group; can be explained by the reduction of VDR gene transcription and VDR expression by decreasing the conversion of inactive vitamin D to active vitamin D. It is not known exactly what the VDR synthesis depends on, but the calcitriol level, calcitriol catabolism. In addition, the changes in PTH, serum calcium, phosphorous level affect VDR synthesis and are shown in these studies (120,121). Again It has been verified that the VDR synthesis varies cell-specific (123,124). The result of our study suggests that vitamin D deficiency is important in renal transplant patients. The end result of this study; D vitamine replacement therapy may have a positive effect on immunological functions, graft survival. However, more research is needed for this. Key words: Renal transplant recipients, vitamin D, vitamin D receptors, chronic allograft rejection.