PROJECT SUMMARY/ABSTRACT Established in 2003, the DILIN currently has 6 clinical centers and one data coordinating center and is recruiting eligible patients with well-defined idiosyncratic DILI into two ongoing multicenter prospective studies. Indiana University is one of the founding clinical centers and has robustly participated in all DILIN operations since its inception. The RFA DK-22-013 was issued to address several new objectives with regards to its risk factors, causality, clinical features and natural history, and potential therapies. We propose the following specific aims to meet the goals of this RFA. Specific Aim # 1: To enroll large number of eligible adults with suspected DILI into ongoing DILIN prospective, acute liver injury, and retrospective studies. We propose to collect prospective and retrospective cases of suspected DILI from multiple sources in Central Indiana, each providing distinctive epidemiological facets and research potential. We propose to utilize the medical informatics and health information exchange infrastructure established by the Regenstrief Institute for Health Care. A special focus of this aim is to robustly enroll the following subpopulations with intense focus on racial and ethnic diverse patients with suspected DILI. Specific Aim # 2: To conduct two distinct ancillary studies, each one adding significantly to our understanding of DILI. These include: (a) To test the hypothesis that plasma whole transcriptome cell-free mRNA serves as an important approach to better understand the mechanisms, phenotypic presentation, and outcomes of patients with suspected DILI. We will conduct plasma cf-mRNA RNA-Seq profiling of patients with suspected acute DILI at baseline and during follow-up to delineate cf-mRNA signatures associated with acute DILI and its phenotypes and outcomes. (b) To test the hypothesis that HLA variants are associated with DILI due to selected agents. This objective builds on successful investigations conducted by DILIN during the current funding period. Specific Aim # 3: DILI carries considerable mortality and morbidity but there is no treatment available other than withdrawing the offending agent. To address this unmet therapeutic need, we propose to conduct a randomized, double-blind, placebo-controlled pilot study of saroglitazar, a novel PPARα/γ agonist in individuals with well characterized cholestatic DILI meeting predefined eligibility criteria. Our hypothesis is that saroglitazar, a potent PPARα agonist attenuates cholestasis and improves recovery of patients with cholestatic DILI. Sixty individuals with definite, highly likely or probable DILI with R<2 and total bilirubin > 3 mg/dL will be randomized to receive either saroglitazar (1 mg once daily) or placebo for 4 weeks. Primary efficacy endpoint is normalization of serum alkaline phosphatase after 4 weeks of intervention. Specific Aim # 4: The objective is to robustly participate in all cross-consortia activities including participat...