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Li, Yihe (2020) Novel pathways involved in nephrotoxicity induced damage and recovery. PhD thesis, University of Nottingham.

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Abstract

Acute kidney injury (AKI) has become a rising global concern affecting over 13 million people every year and one of the main causes is nephrotoxic drugs-induced AKI. Understanding the mechanisms of which and the genetic pathway involved during damage and recovery enable further investigation on targeted treatments. Therefore, the overall aim of this study was to investigate the key genes or pathways involved in nephrotoxic drug-induced damage and recovery, thus help understanding further the paths of damage and potential recovery in nephrotoxic injury.

Firstly, AKI was induced by injecting aristolochic acid (AA) to ICR mice. We found that 5mg/kg bodyweight dose of AA did not cause significant damage to mice kidneys; HK2 cells responded to AA and folic acid (FA) treatments in time-dependent and dose-dependent manner and were able to recover after acute damage. Compare to AA treated cells, FA treated cells tended to detach from the plates after injury, making it easier to observe the recovery process after damage, thus FA at concentration of 18mM was selected for the remainder of the project. During 24-hour FA treatment, the level of both high mobility group box 1 (HMGB1) and light chain 3 B (LC3B) protein increased significantly (p<0.05) and reduced to a normal level during recovery. The inhibition of LC3B protein did not aggravate the injury nor slowed down the recovery process. In addition, the level of GRP78 protein showed a significant increase during FA treatment, indicated an elevation of unfolded or misfolded protein accumulated in ER. Moreover, reactive oxygen species (ROS) level was observed a significant elevation after 4-hour FA treatment, peaked at 24-hour treatment and gradually decreased during recovery period.

Next, RNA-seq was used to investigate the mRNA change during FA treatment and recovery. HMGB1 targeted on translation during FA induced injury and recovery, and potentially induced the expression of pro-inflammatory cytokines through the C-X-C motif chemokine 12 (CXCL12) or toll-like receptor 2 (TLR2) signalling pathways. The mRNA expression of Pax2 was elevated after FA treatment, which indicated Pax2 might have a protective role over FA induced acute injury. Matrix metalloproteinase7 (MMP7) might not have a protective role in this study as its mRNA expression significantly decreased during FA treatment (p<0.05).

In conclusion, FA-induced damage in HK2 cells may be mediated by ROS damage and results in HMGB1 protein induction within a few hours of exposure. Whilst the cells in which this translocation is observed survive, they also induce the expression of pro-inflammatory cytokines potentially through the CXCL12 or TLR2 signalling pathways. The autophagy response is activated after FA injury which may be induced independently or through an HMGB1 mediated process, but it is not solely responsible for enabling the survival seen in FA exposed HK2 cells. The processes identified in this thesis may be helpful in understanding further the paths of damage and potential recovery in nephrotoxic injury.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Welham, S. Gardner, D.
Keywords:	Nephrotoxic injury; Nephrotoxicology; Kidneys; Recovery from injury
Subjects:	R Medicine > RC Internal medicine
Faculties/Schools:	UK Campuses > Faculty of Science > School of Biosciences
Item ID:	60456
Depositing User:	Li, Yihe
Date Deposited:	13 Mar 2024 14:57
Last Modified:	13 Mar 2024 14:58
URI:	https://eprints.nottingham.ac.uk/id/eprint/60456

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