Gene Expression Profiles Indicative of Reversible Injury in Experimental Renal Artery Stenosis

Abstract

AimThe aim of this is to identify the gene expression profiles indicative of reversible versus irreversible injury in experimental (murine) renal artery stenosis (RAS).MethodTwo‐kidney‐one‐cuff hypertension was established by placement of a polytetrafluoroethylene cuff on the right renal artery (N=18). Sham surgery was performed by manipulating the right renal artery without cuff placement (N=6). To determine potential reversibility, the cuff was removed at 7 days (7D cuff‐off, N=6) and 14 days (14D cuff‐off, N=6) after initial RAS surgery. In a control RAS group, the cuff was left in place for 28 days (28D RAS, N=6). Kidneys were harvested at 28 days for assessment of atrophy and fibrosis. Renal blood perfusion and oxygenation were measured using 16.4T MRI. RNASeq analysis was performed on all the groups at 28 days following initial surgery.ResultsFollowing cuff placement, intra‐renal perfusion was reduced by 65% (p<0.0001 vs. baseline). In the 7D cuff‐off group intra‐renal perfusion was restored to baseline values after cuff removal, whereas in the 14D cuff‐off group perfusion was not significantly improved following cuff removal. In the 28D RAS group the reduction in perfusion was maintained throughout the study period.The 7D cuff‐off group had a significantly lower % atrophy (7 ± 2.2%, p=0.0042) and % area of interstitial fibrosis (0.57 ± 0.08 %, p<0.0001) compared to 28D RAS group (atrophy 66 ± 13%, area of fibrosis 7.79 ± 0.89 %). The 14D cuff‐off group had severe atrophy (56 ± 16.6%) and interstitial fibrosis (5.05 ± 1.22%) similar to that seen in 28D RAS group.RNASeq analysis data were normalized to appropriate sham controls in all the groups and was performed at 28 days following initial surgery. Induction of greater than Log2 ratio >2 and p values < 0.00001 were considered significant (following adjustment for multiple comparisons). Fibrosis associated genes were differentially regulated in the 7D cuff‐off compared to the 14D cuff‐off and 28D RAS group (table ).ConclusionWe conclude that cuff removal at 7 days is associated with relative preservation of renal structure, indicating that renal injury at this point is reversible. We have identified a number of fibrosis associated genes that are differentially regulated in the 7D cuff‐off group versus 14D cuff‐off group. Further analysis will determine the functional relevance of these differentially regulated genes.Support or Funding InformationThis project was funded by National Institutes of Health, NIAID R01 AI100911. Values of Log 2 Ratio Genes 7D Cuff‐off vs Sham 14D Cuff‐off vs Sham 28D RAS vs Sham COL1A1 0.96 2.62 2.23 COL1A2 0.79 2.07 1.91 COL3A1 1.26 2.60 2.35 MMP12 1.24 2.85 2.95 MMP14 1.34 2.70 2.55 MMP19 2.89 3.86 4.05 MMP2 1.55 3.49 3.22 MMP7 6.96 9.22 9.59 MTOR −0.46 −1.67 −2.06 SERPINE1 1.25 3.37 2.35 TGFB1i1 0.44 1.46 1.53 TGFB2 0.82 1.83 1.97 TGFB3 0.59 1.91 1.99 TGFBi 0.98 1.88 2.02 KLF15 −0.90 −1.76 −2.60 UBD 4.49 6.23 6.18 TIMP1 2.94 5.30 5.16 TIMP2 0.50 1.46 1.52 TIMP3 −0.35 −1.26 −1.36 HSPB1 0.16 2.00 2.13 HSPB8 1.51 2.26 2.30 CCL2 3.44 4.89 4.31 CCL12 2.88 3.71 4.12 SERPINE1 1.25 3.37 2.35 SERPINE2 1.17 2.39 2.35 SERPINF1 2.02 2.76 3.11 SERPINF2 −0.51 −2.03 −2.71 SERPING1 1.15 1.81 2.09 CLU 1.45 2.54 3.07 STC1 0.45 1.99 2.12 SPP1 1.75 3.06 3.37