APLN and diabetic kidney disease: LPS appeared to selectively cause apoptosis in the tubular cells (Figure 6A), which may explain the significantly decrease in whole tissue apela, but not APJ and apelin. Our finding that apela expression is decreased by LPS and partially restored by Fc-ELA suggests that ELA levels may be a marker of kidney function, which is in line with recent reports that circulatory ELA levels correlate with the ratio of albumin to creatinine in patients with diabetic nephropathy [40].