[HTML][HTML] Albumin stimulates interleukin-8 expression in proximal tubular epithelial cells in vitro and in vivo

S Tang, JCK Leung, K Abe, KW Chan… - The Journal of …, 2003 - Am Soc Clin Investig
S Tang, JCK Leung, K Abe, KW Chan, LYY Chan, TM Chan, KN Lai
The Journal of clinical investigation, 2003Am Soc Clin Investig
Renal tubulointerstitial injury is characterized by inflammatory cell infiltrate; however, the
stimuli for leukocyte recruitment are not fully understood. IL-8 is a potent chemokine
produced by proximal tubular epithelial cells (PTECs). Whether nephrotic proteins stimulate
tubular IL-8 expression remains unknown. Acute exposure of human PTECs to albumin
induced IL-8 gene and protein expression time-and dose-dependently. Apical albumin
predominantly stimulated basolateral IL-8 secretion. Electrophoretic mobility shift assay …
Renal tubulointerstitial injury is characterized by inflammatory cell infiltrate; however, the stimuli for leukocyte recruitment are not fully understood. IL-8 is a potent chemokine produced by proximal tubular epithelial cells (PTECs). Whether nephrotic proteins stimulate tubular IL-8 expression remains unknown. Acute exposure of human PTECs to albumin induced IL-8 gene and protein expression time- and dose-dependently. Apical albumin predominantly stimulated basolateral IL-8 secretion. Electrophoretic mobility shift assay demonstrated nuclear translocation of NF-κB, and the p65/p50 subunits were activated. NF-κB activation and IL-8 secretion were attenuated by the NF-κB inhibitors pyrrolidine dithiocarbamate and cell-permeable peptide. Albumin upregulated intracellular reactive oxygen species (ROS) generation, while exogenous H2O2 stimulated NF-κB translocation and IL-8 secretion. Albumin-induced ROS generation, NF-κB activation, and IL-8 secretion were endocytosis- and PKC-dependent as these downstream events were abrogated by the PI3K inhibitors LY294002 and wortmannin, and the PKC inhibitors GF109203X and staurosporin, respectively. In vivo, IL-8 mRNA expression was localized by in situ hybridization to the proximal tubules in nephrotic kidney tissues. The intensity of IL-8 immunostaining was higher in nephrotic than non-nephrotic subjects. In conclusion, albumin is a strong stimulus for tubular IL-8 expression, which occurs via NF-κB–dependent pathways through PKC activation and ROS generation.
The Journal of Clinical Investigation