Omics-based Predictors of NAFLD/Potential NASH: A New Era Towards Valid and Reliable Non-invasive Diagnosis and Personalized Therapy

The national treatment program intended to provide a cure for Egyptian HCV-infected patients was the sparking light toward an HCV-free and healthy liver among the Egyptian population. However, another rapidly evolving liver disease has been emerging with an increase in both mortality and morbidity, and an estimated prevalence of 25-35% across the globe; non-alcoholic fatty liver disease (NAFLD). The highest rate of NAFLD is reported from the Middle East (32%). The prevalence of NAFLD in the general population increases with age; from 3% in children, 5% in teenagers, 18% between 20 and 40 years, 39% in those aged 40 to 50 years, and to over 40% in those greater than 70 years.

NAFLD is a metabolic disorder, whose spectrum progresses from simple steatosis to non-alcoholic steatohepatitis (NASH) and liver fibrosis, potentially leading to cirrhosis, hepatocellular carcinoma, and liver failure. Accordingly, NASH is considered a severe form of NAFLD. Given the association between NAFLD and the growing global epidemics of obesity, type 2 diabetes, sedentary lifestyles, dyslipidemia, and unhealthy dietary patterns, the prevalence of NAFLD is expected to increase. Therefore, NAFLD is a major clinical and economic burden on the world's healthcare systems.

Although liver biopsy is the reference standard for the assessment of fibrosis associated with NASH, the inherent limitations of an invasive procedure, and the need for repeat sampling, have led to the development of several non-invasive tests (NITs) as alternatives to liver biopsy. The current NITs were used for the diagnosis of advanced fibrosis in patients with NAFLD (5), Such NITs mostly include biological (serum biomarker algorithms) or physical (imaging assessment of tissue stiffness) assessments. However, currently available NITs have several limitations, such as variability, inadequate accuracy, and risk factors for error. The current NITs were used not only to diagnose significant fibrosis in chronic hepatitis C but also the diagnosis of advanced fibrosis in patients with NAFLD/NASH.

In low-resource countries, despite the high prevalence of NAFLD and that its early stages are reversible with diet and lifestyle modifications, the availability of NITs is likely to be limited, especially the more expensive imaging-based tests. Blood-based biomarkers are therefore attractive, but those available to date have only moderate diagnostic accuracy. Furthermore, only a minority of NAFLD cases are diagnosed and correctly treated as detecting early stages is hindered by a lack of non-invasive reliable, and validated methods of early diagnosis. In addition, there are few options available for the management of NASH and no current FDA-approved therapies for NAFLD.

To date, the pathogenesis of NAFLD is not fully clarified. NAFLD is thought to be involved in complex interactions among diet, genetic susceptibility, and gut microbiota (6). At the same time, the role of gut microbiota and microbial metabolites in NAFLD has attracted more attention. Gut microbiota regulates the development and progression of NAFLD on the basis of the gut-liver axis. Future targeted treatment strategies based on the pathogenic pathways are accordingly needed to develop an effective treatment for patients with NASH.