(625.3) Transcriptomic and metabolic profiling of Tolvaptan treated Autosomal dominant polycystic kidney disease (ADPKD) patient

Poster Board Number: E667

Hugo Lin (Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University), Frank Xu (Carnegie Mellon University), Li-Lun Ho (Massachusetts Institute of Technology), Li-Ju Huang (Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University), Tzongshi Lu (Brigham and Womens Hospital, Harvard Medical School)

Background
Autosomal dominant polycystic kidney disease (ADPKD) is the most common and life-threatening genetic kidney disease that characterized by the aberrant renal tubule epithelial cells proliferation leads to the formation of multiple fluid-filled cysts, and most of the ADPKD patient will leads to kidney failure by age of 50. Currently, dialysis or a transplant are the only treatments for end-stage ADPKD patients. Tolvaptan is a is a selective vasopressin V2-receptor antagonist which was used to treat hyponatremia in heart failure but was approved by FDA for ADPKD treatment in 2018. However, there are limitations for ADPKD patients to receive Tolvaptan treatment and significant side effects severely affect patient’s life quality. 
In our study, a 34-year-old man was diagnosed with familial ADPKD. He had cysts in kidney (Mayo class 1c) and liver and showed no symptoms other than hypertension. His baseline eGFR was 76.98 ml/min/1.732mg/dL but declined to 57.02 ml/min/1.732mg/dL two years after his first diagnosis, and there was an increase in number and size of the cysts due to the rapidly progressive ADPKD. Tolvaptan was started with the 45-0-15 dose and the patient was well-tolerated. After 60 days of treatment, the renal function dramatic improved (73.02 ml/min/1.732mg/dL). With the titrate to 60-0-30 dose of tolvaptan, his eGFR maintains above than 60 ml/min/1.732mg/dL more than 3 months until present. 

Method
Information of transcriptome and metabolome has significantly contributed to identifying potential therapeutic targets for the management of diseases. In our study, we collect his blood and urine before Tolvaptan treatment and 2 and 3 months after Tolvaptan treatment for transcriptomic and metabolic profiling. Total RNA was extracted using Trizol® Reagent (Invitrogen, USA) according to the manual. cDNA libraries were prepared by SureSelect XT HS2 mRNA Library Preparation kit (Agilent, USA) and sequenced on Nextseq. Differential expression analysis was performed using StringTie and DEseq2 with genome bias detection/correction using Welgene Biotechs in-house pipeline. Genes with p value lt; 0.05 and gt; 2.0-fold changes were considered significantly differentially expressed, and functional enrichment assay in differentially expressed genes of each experiment design was performed using clusterProfiler v3.6.

Results
Our data indicates that tight junction proteins (Log2 ratio: CRB3, 11.01; CLDN10, 10.09; MAPK10, 7.34), cytoskeleton regulating proteins (Log2 ratio: FGF17, 9.47; MYH14, 7.04) which also genes involved in the regulation of calcium and MAPK signaling and following focal adhesion proteins were significantly (plt;0.05) preserved after 3 months Tolvaptan treatment. Furthermore, Hypoxanthine, Creatine, L-a-aminobutyric acid and Trimethylamine N-oxide were significantly decreased in our metabolomics data analysis which is also indicates the inhibition of paracellular transportation in kidney epithelial/endothelial cells. 

Conclusion
Our data indicates a potential molecular mechanism of Tolvaptan treatment in regulating the integrity of tight junction and kidney cells, and provides novel therapeutic targets in in ADPKD.