Neprilysin Inhibition by an Antisense Oligonucleotide (ASO) Ameliorates Kidney Damage in a Salt‐induced Rat Chronic Kidney Disease Model
Authors: Yeh Steve Ting‐Yuan , Mullick Adam , Kuo Carol , Graham Mark , Crooke Rosanne 
Published: June 2021

Neprilysin (NEP) is the key enzyme that degrades natriuretic peptides (NPs), which are the neurohormones contributing to natriuresis, diuresis and blood pressure regulation. NEP inhibition results in enhanced natriuresis and vasodilation by augmenting NP levels, which lead to the reduction of intra‐glomerular pressure and proteinuria in the damaged kidneys. We evaluated the renoprotective effects of a Generation 2.5 NEP antisense oligonucleotide (ASO) in a hypertensive and salt‐induced severe chronic kidney disease (CKD) model. Male, uninephrectomized (UNX) spontaneously hypertensive rats (SHR) were randomized to concurrently receive seven weeks of high salt intake (1% NaCl in drinking water for 5 weeks and then 1.5% for remaining two weeks) and drug treatments (vehicle control, NEP ASO at 20 mg/kg SQ weekly or the small molecule NEP inhibitor AHU377 at 50 mg/kg PO daily). AHU377 (Sacubitril) is the main ingredient of the recently approved heart failure drug Entresto®. Age‐matched SHR naïve (SHR control, normal salt intake) and SHRs with UNX (UnX control, normal salt intake + UnX) served as negative controls. NEP ASO treated rats demonstrated improvements in proteinuria compared to vehicle control or AHU377 treatments1. There were no differences between the treatment groups in blood BUN, creatinine level and creatinine clearance. In the NEP ASO group, kidney qPCR analysis demonstrated marked reductions of NEP expression (>90%) and significantly less inflammation (MCP1, KIM1, NGAL) and fibrosis (ColIa1) relative to control or AHU377 treatments2. Western blot and NEP activity assays of kidney homogenates corroborated the qPCR findings. Meanwhile, NEP ASO and AHU377 treatments restored urinary cGMP/creatinine ratio3 suppressed by salt‐induced kidney damage. Histological examination of the kidney revealed less interstitial fibrosis, eosinophilic casts and glomerulosclerosis with NEP ASO treatment. In summary, in a severe rat CKD model, NEP ASO treatment was effective in blunting disease progression (i.e. less proteinuria, inflammation and fibrosis), which was not observed with the treatment by a small molecular NEP inhibitor AHU377.

SHR control
UnX control
UnX, salt + vehicle
UnX, salt + NEP ASO
UnX, salt + AHU377

1
MicroAlb/CRE (mg/ml/mg/dL)
0.22 ± 0.04
1.25 ± 0.23
16.2 ± 3.3
2.40 ± 0.80**
26.3 ± 10.1

2
MCP1 gene expression (%)
100 ± 8
121 ± 8
347 ± 48
239 ± 18*
351 ± 31

KIM1 gene expression (%)
100 ± 28
248 ± 47
10,189 ± 2,382
1,430 ± 307*
18,970 ± 12,266

NGAL gene expression (%)
100 ± 7
157 ± 7
1,870 ± 387
463 ± 36**
1,987 ± 794

ColIa1 gene expression (%)
100 ± 10
139 ± 13
753 ± 122
474 ± 28*
752 ± 95

3
Urinary cGMP/CRE (pmol/ml/mg/dL)
33.6 ± 4.6
26.6 ± 2.4
19.5 ± 1.6
26.4 ± 2.2*
34.4 ± 4.2

1(UnX, salt + vehicle) vs. (UnX, salt + NEP ASO): ** p < 0.01
2(UnX, salt + vehicle) vs. (UnX, salt + NEP ASO): * p < 0.05, ** p < 0.01
3(UnX, salt + vehicle) vs. (UnX, salt + NEP ASO): * p < 0.05

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.