HYPERTENSIVE NEPHROPATHY: TRANSCRIPTOMICS OF KIDNEY BIOPSIES PREDICTS LONG TERM OUTCOME AND IDENTIFIES THERAPEUTIC TARGETS

Abstract

Objective: Hypertensive nephropathy (HN) represents a major cause of chronic kidney disease, but it is incompletely understood why some patients show disease progression. Our project aim is to identify potential markers of disease progression and novel therapeutic targets. Design and method: Adult patients (n=43; n=16 females, mean age 53 years) with biopsy-verified HN were categorized as ’early’ (estimated glomerular filtration rate (eGFR) >45 ml/min/1.73m2) or ’late’ disease (eGFR <45 ml/min/1.73m2) at the time of biopsy. Patients were further divided into “stable” (eGFR decline <3 ml/min/year) or “progressive” (eGFR decline >3 ml/min/year or start of renal replacement therapy) after median follow-up of 10 years (5-22). TruSeq Exome sequencing was executed after RNA extraction (miRNeasy FFPE kit, Qiagen) at Novogene, Cambridge, UK. Quality control and data analysis was performed using R Studio (v4.2.0) and QIAGEN Ingenuity Pathway Analysis. Results: We analyzed the following subgroups of HN patients: early stable (ES, n=11), early progressive (EP, n=11), late stable (LS, n=9) and late progressive (LP, n=12). Differentially expressed genes (DEG, fold change (FC) >1.5 and p-value < 0.05) were identified, with n=265 in ES vs. EP, and n=674 in LS vs. LP. Principal component analysis (PCA) showed separation of ES vs. EP and LS vs. LP, as depicted in Figure 1A and B. K-nearest neighbour (KNN) analysis of DEG identified a 6-gene classifier in LS vs. LP (19/21 samples correctly classified), while IER5L and CNTNAP5 were the top 2-gene classifier in ES vs. EP (20/21 samples). These classifiers, as well as other DEGs such as PER1, YB1, TIMP3, ADAMTS4, IGFBP5 and EGF could represent novel targets to inhibit disease progression. Differentially regulated pathways were associated with regulation of TP53 activity and circadian rhythm involving melatonin metabolism in ES vs. EP, and metabolic processes related to water-soluble vitamins, glutathione and sphingolipids in LS vs. LP. Conclusions: Transcriptomic profiling from diagnostic kidney biopsies with HN can distinguish future disease progression from non-progression and may identify novel therapeutic targets.