Up-regulation of Slc39A2(Zip2) mRNA in peripheral blood mononuclear cells from patients with pulmonary tuberculosis

Zinc is the most common trace mineral after iron in the human body. In organisms, zinc transporters help zinc influx and efflux from cells. A previous study has reported that Zip2 was up-regulated over 27-fold in human monocytic THP-1 cells, when intracellular zinc was depleted by TPEN. Our study found Zip2 was over-expressed in leukocytes of asthmatic infants, especially those in which the serum zinc level was lower than those in healthy infants. Pulmonary tuberculosis (PTB) patients have significantly low serum zinc levels. Here we investigated whether Zip2 level was changed in the patients with PTB. Zip2 mRNA and protein levels in peripheral blood mononuclear cells (PBMC) from PTB (n1 = 23) and healthy controls (n2 = 42) were detected by quantitative real-time PCR and western blot, respectively. mRNA expression levels of another four zinc transporters, Zip1, Zip6, Zip8 and ZnT1, were detected by quantitative real-time PCR. Zip2 mRNA level was significantly up-regulated in PTB patients (P = 0.001), and Zip8 mRNA level was significantly down-regulated compared with control individuals (P < 0.001). In contrast, there were no significant changes in mRNA levels of Zip1, Zip6 and ZnT1 in either group (P > 0.05). Zip2 protein expression levels increased in PTB patients compared with control individuals. Our study found that knockdown of ZIP2 with siRNA caused a decrease in Zip2 levels in PBMC of PTB patients, while reducing the expression of INF-γ (P < 0.01) and increasing the expression of IL-6(P < 0.01). These data provide evidence that increased expression of Zip2 gene is closely associated with immunity of PTB patients, suggesting that the Zip2 gene may play a key role in the initial infection control of the human body, by promoting and maintaining the immune response of adaptive T cells.