Abstract
Acute Kidney Injury (AKI) is now recognised to be a precursor to developing later onset fibrosis and Chronic Kidney Disease (CKD). Kristen Ras (Kras) is a monomeric GTPase involved in the signalling cascades that lead to the development of fibrosis. This study has established a murine model of Aristolochic Acid Nephropathy (AAN) that creates an AKI that recovers but then leads to CKD. This model was then used to target Kras transcription with an Antisense Oligonucleotide (ASO) in the peri AKI period with the aim of reducing downstream fibrosis.CD1 mice were given two doses of 3.5mg/kg Aristolochic Acid via intraperitoneal injections, the first on Day 1 and the second on Day 5. The duration of the model was 100 days with sacrifice and sampling performed throughout to characterise the model. The model was repeated with mice that were separated into two groups. Each group received a single dose of 100mg/kg ASO 143 (designed to target Kras) via a subcutaneous injection but one group was given an early injection at Day -2 whilst the other was administered a late injection at Day 20. In each group were vehicle controls and mice that received cASO 230 (a control ASO) instead.
The model demonstrated an AKI that peaked at Day 12 and soon after recovered. By Day 100 the diseased mice had developed CKD that was demonstrated both functionally and histologically. Early treatment with ASO 143 at Day -2 had no impact on the AKI but it did reduce Kras transcription by 34% at Day 0 and expression by 25% at Day 12, it caused a 25% fall in TNFa transcription at Day 0 which fell to 56% by Day 20 and ultimately it resulted in a 57% reduction in fibrosis by Day 100 compared to vehicle treated mice. Late administration of ASO 143 at Day 20 had no impact on either the functional or histological markers of fibrosis at Day 100.
An additional piece of work looked at using an adapted Gadolinium agent (Gd-ESMA) with MRI to identify fibrosis in a rat model of UUO but this proved unsuccessful due to the problems encountered with the UUO model.
In conclusion, a single dose of early ASO therapy targeting Kras expression before the onset of the AKI in a murine model of AAN reduced the fibrosis that develops and the functional impairment of CKD through both reducing early Kras expression and the inflammatory response to the AKI. This may herald a new therapeutic approach to preventing renal fibrosis.
| Date of Award | 1 Sept 2019 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Claire Sharpe (Supervisor) & Bruce Hendry (Supervisor) |