Changes In Peripheral Blood CD4⁺ Regulatory T Cells And 25-Hydroxyvitamin D₃ And Their Clinical Significance In Patients With Type 2 Diabetic Peripheral Neuropathy

Objective:To investigate the expression levels of 25-hydroxyvitamin D3[25-(OH)D3]and CD4+ regulatory T cells(Treg cells)in peripheral blood of patients with type 2 diabetes peripheral neuropathy(DPN)and without type 2 diabetes peripheral neuropathy(NDPN),so as to explore the underlying mechanism in type 2 DPN regulated by 25-(OH)D3 and Treg cells.Our study aims to provide experimental basis for predicting,treating and prognosing DPN.Methods:A total of 56 cases with type 2 diabetes who were treated in our Hospital from January 2017 to July 2017 were enrolled into the study.Enrolled patients were divided into type 2 diabetes peripheral neuropathy group(n=28)and without type 2 diabetes peripheral neuropathy group(n=28)according to examinations of clinical signs,symptoms and electrophysiological sensory testing.After the patients were enrolled,the differences of age,body mass index(BMI),glycosylated hemoglobin,urine microalbumin,blood urea nitrogen(BUN),serum creatinine,blood lipid analysis and 24-h urine microalbumin were firstly analyzed.Peripheral blood sample was harvested in every patient,and electrochemiluminescence immunoassay was used to measure the peripheral blood 25-(OH)D3 level in type 2 diabetes peripheral neuropathy group and non-type 2 diabetes peripheral neuropathy group.Next,flow cytometry was utilized to analyze the expression level of CD4+Treg cells in each patient from the two groups.Data were analyzed by conducting the Student t-test and the correlation between peripheral levels of 25-(OH)D3 and expression levels of CD4+Treg cells were analyzed by Pearson correlation analysis.P<0.05 indicated that the difference was statistically significant.Results:(1)There were no significant differences in age,body mass index,glycosylated hemoglobin,urine microalbumin,blood urea nitrogen,serum creatinine,blood lipid analysis and 24h urine microalbumin,between type 2 diabetes peripheral neuropathy group and non-type 2 diabetes peripheral neuropathy group;(2)Compared with patients in non-type 2 diabetes peripheral neuropathy group(52.85 ±A.73 nmol/L),the expression level of 25-(OH)D3 in the type 2 diabetes peripheral neuropathy group was significantly lower(47.82± 7.72 nmol/L),the difference was statistically significant(p = 0.026).(3)Compared with non-type 2 diabetes peripheral neuropathy group(3.51%± 0.58%),the expression level of CD4+Treg cells in type 2 diabetes peripheral neuropathy group(3.04%± 0.50%)was significantly decreased,the difference was statistically significant(p = 0.002);(4)Peripheral blood level of CD4+Treg cells was positively correlated with the expression level of 25-(OH)D3(r = 0.436,p = 0.001).Conclusion:The expression levels of 25-(OH)D3 and CD4+Treg cells in patients with type 2 diabetes peripheral neuropathy was significantly lower compared with those diabetic patients without peripheral neuropathy.Besides,peripheral blood level of CD4+Treg cells was positively correlated with the expression level of 25-(OH)D3.Our study illustrates that 25-(OH)D3 may influence the development and progression of type 2 diabetes peripheral neuropathy via regulating the expression level of CD4+Treg cells,which provides the basis for further revealing the pathogenesis of type 2 diabetes peripheral neuropathy.