Non-alcoholic fatty liver disease (NAFLD) is a common condition that affects >25 % of the population worldwide.1 This progressive disorder ranges in severity from simple steatosis to severe steatohepatitis (NASH) and, with the advanced stages of fibrosis, can potentially progress to liver cancer.2 A high proportion (between 35 and 50 %) of liver cancer occurs in patients with NASH.3,4 Compared to hepatic tumors with other etiologies, these NASH-related tumors are often larger in size and less responsive to therapy.5 The major underlying cause of NAFLD is excessive fat consumption which causes the accumulation of lipids in the liver.6 NASH is at the severe end of the NAFLD spectrum and is characterized by inflammation.2,6,7 Cirrhosis and liver cancer are known to be provoked by the activation of a cascade of pro-fibrogenic and pro-inflammatory cytokines as well as ongoing liver injury with the development of fibrosis.6 Activation of hepatic stellate cells, insulin resistance, oxidative stress, mitochondrial dysfunction, aberrant release of cytokines and adipokines, obesity and lack of exercise have all been linked to the etiology and progression of NAFLD.8,9 Although the pathophysiology of NAFLD is well defined, work to identify therapeutic targets and advances in drug research is still ongoing, and no definitive treatments are yet available for this disorder. Many genes have been reported as having a role in the pathogenesis and progression of NAFLD, such as genes known to be involved in hepatic lipid metabolism and inflammation and fibrotic pathways.10, 11, 12, 13, 14 A number of studies have identified defects in the function or overexpression of genes and proteins as critical factors in the initiation and progression of NAFLD.15,16 There is a clear need to develop multifaceted therapies that target the risk factors associated with these illnesses in order to go beyond the constraints of traditional medications.17, 18, 19 Dysregulation or dysfunction of specific genes and pathways might lead to the initiation and progression of NAFLD and these could represent important therapeutic targets.11, 12, 13,20,21

In our previous bioinformatics and in vitro research, we reported that certain genes, specifically Tumor Necrosis Factor (TNF), Toll-Like Receptor 4 (TLR4), Stearoyl-CoA Desaturase (SCD), Fatty acid synthase (FASN), Sterol Regulatory Element Binding Transcription Factor 2 (SREBF2) and transforming growth factor beta-1 (TGFβ-1), were overexpressed in in vitro models of NAFLD and are also implicated in diverse stages of NAFLD including steatosis, inflammation and fibrosis.22

Nucleic acid-based medicines have recently undergone significant development and have shown tremendous potential as a therapeutic platform in treating a variety of disorders, some of which have already received FDA (US Food and Drug Administration) approval.19,23

Published studies have confirmed the effectiveness of nucleic acid-based therapeutics in the management of NAFLD. MicroRNAs are small (19–25 nucleotides) non-coding RNAs that could offer great potential as therapeutic agents in the cure of diseases such as NAFLD.14,24 MiRNAs act as gene silencers through 3′ UTR gene binding and have several benefits such as multiple targeting and low cost in comparison to other nucleic acid-based treatments, making them excellent therapeutic candidates.25 Approximately 2200 miRNA genes exist in the mammalian genome, and they are known to influence important cellular processes including development, growth, differentiation and metabolism. Approximately one-third of the human genome is thought to be controlled by miRNAs.26 Available evidence confirms the role of miRNAs in regulating important genes related to hepatic steatosis and steatohepatitis.24,27 Regulating the most important of these genes by miRNAs represents a novel approach for treating disorders such as NAFLD. In our previous in-silico study, we indicated miR-124 and miR-16 in particular have been shown to impact several processes central to NAFLD development, such as lipid homeostasis, autophagy, oxidative stress response, cytokine production involved in immune response, and modulation of inflammatory responses.22 Additionally, both miRNAs inhibit TLR4 signaling and directly target genes modulating lipid metabolism and fibrosis.28., 29, 30., 31 Prior studies identified alternation of expression of miR-124 and miR-16 in NAFLD animal models.32,33 Due to their roles modulating innate immune reaction, metabolic dysfunction and cross-talk between inflammatory cascades, we hypothesize miR-124 and miR-16 may hold therapeutic potential for treating NAFLD through coordinated modulation of multiple susceptibility pathways. Subsequently, we transfected two key miRNAs (miR-124 and miR-16) identified in our previous study that are known to target NAFLD-related genes including TNF, TLR4, SCD, FASN, SREBF2 and TGFβ-1.22