Lipopolysaccharide-induced expression of surfactant protein A subtypes in human renal tubular epithelial cells / 中华肾脏病杂志

ABSTRACT

Objective To determine the surfactant protein A (SP-A) subtype distribution and expression in human renal tissue and cultured human renal tubular epithelial cells(HK-2), and to explore the influence of Lipopolysaccharide (LPS) on the expression of SP-A subtypes mRNA and SP-A protein. Methods lmmunohistochemical staining was performed using SP-A polyclonal antibodies. RT-PCR was performed with mRNA from HK-2 cells and normal human kidney.Restriction fragment length polymorphism(RFLP) and sequencing were used to evaluate the subtypes of SP-A. The relative content of SP-A mRNA in human kidney and human lung was compared by real-time PCR. Western blotting analysis for SP-A was performed on protein from renal tissue and cultured HK-2 cells SP-A protein in human urine and culture supernatant of HK-2 cells was measured by enzyme-linked immunosorbent assay (ELISA) and Western blotting respectively. HK-2cells were treated with LPS at various concentrations (0,0.1,1,2,5,10 mg/L) for 8 h and at 5mg/L for various time points (0,2,4,8,16,24 h). Expression of SP-A mRNA and protein was analyzed by RT-PCR and Western blotting. Results SP-A was localized in renal tubular epithelial cells of both proximal and distal convoluted tubules. SP-A1, SP-A2 mRNA and protein could be detected in normal HK-2 cells and human kidney. The significant secretion of SP-A [urine (106.614172.772) nmol/L, n=30; culture supernatant (85.533±58.622) nmol/L, n=10] was shown. The levels of SP-A1, SP-A2 mRNA and Sp-A protein in HK-2 cells were significantly decreased after treatment with LPS. Conclusions Human renal tubular epithelial cells can express both SP-A1 and SP-A2 genes which may play an important role in inflammation modulation of kidney.