Data from: Downregulation of autophagy is associated with severe ischemia-reperfusion-induced acute kidney injury in overexpressing C-reactive protein mice

C-reactive protein (CRP), was recently reported to be closely associated
with poor renal function in patients with acute kidney injury (AKI), but
whether CRP is pathogenic or a mere biomarker in AKI remains largely
unclear. Impaired autophagy is known to exacerbate renal
ischemia-reperfusion injury (IRI). We examined whether the pathogenic role
of CRP in AKI is associated with reduction of autophagy. We mated
transgenic rabbit CRP over-expressing mice (Tg-CRP) with two autophagy
reporter mouse lines, Tg-GFP-LC3 mice (LC3) and Tg-RFP-GFP-LC3 mice
(RG-LC3) respectively to generate Tg-CRP-GFP-LC3 mice (PLC3) and
Tg-CRP-RFP-GFP-LC3 mice (PRG-LC3). AKI was induced by IRI. Compared with
LC3 mice, PLC3 mice developed more severe kidney damage after IRI. Renal
tubules were isolated from LC3 mice at baseline for primary culture. OKP
cells were transiently transfected with GFP-LC3 plasmid. CRP addition
exacerbated lactate dehydrogenase release from both cell types.
Immunoblots showed lower LC-3 II/I ratios and higher levels of p62,
markers of reduced autophagy flux, in the kidneys of PLC3 mice compared to
LC3 mice after IRI, and in primary cultured renal tubules and OKP cells
treated with CRP and H2O2 compared to H2O2 alone. Immunohistochemistry
showed much fewer LC-3 punctae, and electron microscopy showed fewer
autophagosomes in kidneys of PLC3 mice compared to LC3 mice after IRI.
Similarly, CRP addition reduced GFP-LC3 punctae induced by H2O2 in primary
cultured proximal tubules and in GFP-LC3 plasmid transfected OKP cells.
Rapamycin, an autophagy inducer, rescued impaired autophagy and reduced
renal injury in vivo. In summary, it was suggested that CRP be more than
mere biomarker in AKI, and render the kidney more susceptible to
ischemic/oxidative injury, which is associated with down-regulating
autophagy flux.