MicroRNAs as diagnostic biomarkers of the evolution of liver damage and role in disease in elderly patients

Ageing increases the risk of various liver diseases, including non-alcoholic fatty liver disease (NASH) and associated comorbidities. The global prevalence of NASH is estimated to be around 24-30% and is expected to continue to grow significantly due to increased obesity and other metabolic disorders (Younossi et al., 2018). In addition, the number of patients progressing to more severe stages of the disease is also increasing, reflecting the aging population; in the United States alone, NASH is already the second most frequent indication for liver transplantation, with a prevalence of NASH cases predicted to increase to 27 million by 2030 (Estes et al., 2018). In parallel, cases of advanced liver disease, cirrhosis and HCC are increasing. It is therefore not surprising that the weight of NASH in the outcomes perceived by patients and in the economy is also increasing (Younossi et al., 2018). Since there is currently no approved pharmacological therapy for NASH, clinical and preclinical trials must be transformed and adapted to respond to this enormous unmet need.

Unfortunately, this has proved a difficult task due to the asymptomatic nature of NASH, its heterogeneous aetiology and pathogenesis, and the absence of minimally invasive biomarkers of disease stage, among other causes (Filozof et al., 2017).

Liver biopsy remains the most reliable method for the diagnosis of the disease, in particular to distinguish between relatively benign stages (steatosis) and severe stages (nonalcoholic steatohepatitis (NASH)). Due to its invasive nature, the procedure is of particular concern in the elderly population, and the identification of specific non-invasive biomarkers is eagerly awaited. In this sense, circulating microRNAs represent excellent candidates, although they need to be evaluated in well-characterized patient cohorts and their possible functional role in the liver clarified.

This project aims to address several of these problematic aspects in elderly patients; having tools to diagnose NAFLD patients in early stages is extremely important, considering the high probabilities of progression to more severe stages, including HCC. In fact, other changes associated with aging, such as those affecting the innate immune system of the liver, then play a significant role in the transition from hepatic steatosis to NASH and in its progression to cirrhosis and HCC (Gong et al., 2017). In this sense, the possibility of using microRNAs as new biomarkers of hepatopathies is particularly interesting, since they are a representative image of hepatic parental cells at the time of their release and change immediately according to the physiopathological state of the liver (Szabo et al.2017; Afonso et al., 2016). Early diagnosis of liver tumors in older patients also needs to be improved, as well as identifying subgroups of patients with different prognosis and response to treatment, which could also be achieved by miRNA-based analysis. At the same time, it is very important to rely on solid preclinical models, recapitulating the results obtained in patients, to conduct appropriate studies and identify possible therapeutic strategies, which is the ultimate goal of this proposal.

In short, in this project, samples will be collected and collected from patients > 60 years with liver disease, in particular patients with good NASH (Obj. 1). Serum samples will be used to determine the expression of circulating miRNAs and correlate it with clinical data to identify potential biomarkers of the disease (Obj. 2). To confirm the specificity of biomarkers for NASH, miRNAs will be screened in sera of older patients with PSC, HCC and CCA, and in healthy subjects. The miRNAs will then be transferred to animal NASH models (Obj. 3), which will allow selection of the model that most closely resembles the human NASH microRNA, and thus validate its use in preclinical trials for the development of new drugs. The possible functional role of identified miRNAs will also be investigated in the samples of this model to determine whether therapeutic targets could be possible (Obj.4).

In the end, the correct identification and management of elderly patients with NASH is one of the major tasks of the geriatric and hepatological physicians that OLD-HEPAMARKER aims to address through the identification of biomarkers of the disease and potential therapeutic targets, thus generating complementary solutions around this public health demand.

References

- Afonso MB, Rodrigues PM, Simão AL, Castro RE. Circulating microRNAs as potential biomarkers in non-alcoholic fatty liver disease and hepatocellular carcinoma. J Clin Med. 2016 Mar 3;5(3).

- Estes C, Razavi H, Loomba R, Younossi Z, Sanyal AJ. Modeling the epidemic of nonalcoholic fatty liver disease demonstrates an exponential increase in burden of disease. Hepatology2018;67:123-133.

- Filozof C, Chow SC, Dimick-Santos L, Chen YF, Williams RN, Goldstein BJ, et al. Clinical endpoints and adaptive clinical trials in precirrhotic nonalcoholic steatohepatitis: Facilitating development approaches for an emerging epidemic. Hepatol Commun 2017; 1: 577-585.

- Gong Z, Tas E, Yakar S, Muzumdar R Hepatic lipid metabolism and non-alcoholic fatty liver disease in aging. Mol Cell Endocrinol. 2017; 455: 115-130.

- Szabo G and Momen-Heravi F. Extracellular vesicles in liver disease and potential as biomarkers and therapeutic targets. Nat Rev Gastroenterol Hepatol 2017; 14: 455-466.

- Younossi Z, Anstee QM, Marietti M, Hardy T, Henry L, Eslam M, et al. Global burden of NAFLD and NASH: trends, predictions, risk factors and prevention. Nat Rev Gastroenterol Hepatol 2018; 15: 11-20.