Effects of L-Carnitine Supplementation on MicroRNA-217 Expression Level in Non-alcoholic Steatohepatitis Suffering Patients with Obesity: A Randomized Controlled Trial

Nonalcoholic steatohepatitis (NASH) is a severe subtype of Nonalcoholic fatty liver disease (NAFLD) and a progressive chronic liver disease which is associated with oxidative stress, inammation, brosis, lipotoxicity, and altered mitochondrial metabolism. Silent Information Regulator 1 (SIRT1) gene is considered as a potential therapeutic target in NAFLD, microRNA-217 (MiRNA-217) inhibits expression of SIRT1 and this inhibition may play role in the pathogenesis of NASH. On the other hand, L-carnitine may have benecial effects on NASH. Therefore, we investigated the effect of L-carnitine on the MiRNA-217 expression levels in obese NASH suffering patients.


Results
MiRNA-217 expression level was higher in NASH suffering group compared to NASH negative obese patients (P < 0.001). There was a signi cant difference in the expression level of MiRNA-217 between Lcarnitine and placebo receiving groups after the study intervention (P = 0.001); while the expression levels had no signi cant difference between the two groups at the initiation of the study. L-carnitine supplementation reduced MiRNA-217 expression levels in participants who were assigned to the supplementation group; while MiRNA-217 expression levels in the placebo received NASH, positive obese patients didn't change during the study.

Conclusion
MiRNA-217 expression level can be considered as a noninvasive practical biomarker for diagnosis, and treatment follow-up of NASH suffering patients. However, further studies are required to nd out the exact relationships between MiRNA-217 expression and different stages of NAFLD. Non-alcoholic fatty liver disease (NAFLD) is characterized by fat accumulation in liver tissue which involves up to 74% of obese adults worldwide 1,2 . Nonalcoholic steatohepatitis (NASH) is a severe subtype of NAFLD with chronic necroin ammation and hepatocytes injury that is considered as progressive chronic liver disease and may be complicated by liver brosis, hepatic cirrhosis, liver failure and hepatocellular carcinoma 3,4 .
According to Multiple Parallel Hit hypothesis, NAFLD and its progression to NASH, cirrhosis and liver failure depend upon several factors including nutritional risk factors, lack of physical activity, insulin resistance, mitochondrial dysfunction, altered adipokines metabolism, oxidative stress, genetic susceptibility factors, epigenetic factors and lipotoxicity 5,6 .
Life style modi cation including nutrition counseling, gradual weight loss planning, and routine physical activity, in addition to pharmacologic interventions and surgical procedures are different therapeutic strategies to minimize obesity-induced NASH and its co-morbidities and challenges in patients 7 .
According to previous studies, Silent Information Regulator 1 (SIRT1) gene, which plays a critical role in hepatic lipid metabolism, reducing hepatic in ammation and oxidative stress, is considered as a potential therapeutic target in NAFLD suffering patients 8 . Previous studies demonstrated that microRNA-217 (MiRNA-217) inhibits SIRT1 expression and this inhibition may play an important role in the pathogenesis of NASH also 9 . On the other hand, L-carnitine plays a crucial role in fatty acids transportation thorough mitochondrial membrane and hepatic lipid metabolism and may have bene cial effects on NASH in obese patients 10 . Therefore, in the present study, we aimed to investigate the effect of L-carnitine on the expression of MiRNA-217 in obese NASH suffering patients. NASH (Alanine Aminotransferase (ALT) > 3 times more than the upper limit of the normal range and con rmatory ultrasonography outcomes), were eligible to be enrolled to the randomization process to receive supplement/placebo. Pregnancy, smoking, Insulin usage, receiving lipid-lowering drugs as well as steroidal and non-steroidal anti-in ammatory drugs, and antioxidant supplements, viral hepatitis, history of Cushing disease, hyperthyroidism and Wilson ' s disease were considered as exclusion criteria. All patients with eligibility criteria during the study period (71 subjects) were enrolled. At the same time, 36 age, sex, and BMI matched NAFLD/NASH negative obese subjects (by ALT test and ultrasonography ndings) who were on weight loss program were enrolled and assigned to the control group. Venous blood samples were taken from all participant before and after intervention.

Interventions and Randomization
Firstly, all the participants were visited by an expert dietitian at the baseline of the study; a 3-day food recall was ful lled by each participant to calculate his/her energy and nutrient intake and a 500 Kcal de cit in daily caloric intake was applied to the recommended diet which was planned by the dietitian. Moreover, a 30-minute light to moderate exercise program for at least 3 days per week was recommended to all participants.
The randomization in assigning samples into the intervention or placebo receiving groups was performed based on a random numbers table which was computer generated by an independent research assistant. Sequentially numbered containers were used for the implementation of the random allocation sequence. All the participants and main researchers were blind to group allocation. Moreover, the study statistician was blind to group allocation prior to the analysis.
L-carnitine in form of 250 mg tablets (Totally 2000 mg/day, manufactured by [removed for blind peer review]) was administered to the patients who were assigned to the supplementation group for 12 weeks; while the placebo tablets were administered in similar shape, appearance and color to the placebo receiving group. Protocol adherence of each participant was applied by pill count strategy and consumption of >80% of the administered supplement/placebo was considered as positive compliance to the treatment.

Assessments
Weight of patients was measured by a digital scale with minimum clothes and without shoes with an accuracy of 100 grams. Height was measured by an upstretched tape with a maximum error of 0.5 centimeters in a near-wall standing position. In order to assess miRNA expression, 5 mL of fasting intravenous blood was taken from each participant at the study baseline and at the end of study (12 weeks supplementation/placebo administration).

MiRNA expression analysis
Analysis of miRNA expression was performed by Relative quantitative real-time PCR using TaqMan prob technology. MicroRNAs was extracted from plasma samples using the mirvana paris kit (Ambion, AM1556) according to manufacturer's instruction. cDNAs were synthesized with MicroRNA-217 and MicroRNA-23b stem-loop primers, using AccuPower®CycleScript RT PreMix (Bioneer company, K-2046). Sequence of primers and probes are shown in table 1. Relative quantitative Real time PCR was carried out in 20ul reaction mixture containing 200 unit taq DNA polymerase enzyme and 0.25uM stem loop primers and probes. MicroRNA-23b was used as the reference MicroRNA. All reactions were performed as triplicate.

Results
After the eligibility assessment, 71 patients who met the inclusion criteria were randomly assigned to either the supplement or placebo groups. Of the 35 patients assigned to the placebo group, 5 patients were excluded due to unwillingness to continue their participation in the study. Finally, 36 patients received L-carnitine supplementation and 31 obese NASH positive patients received the placebo. Moreover, 34 obese NASH negative control subjects were enrolled in the study, while two cases excluded following their unwillingness to participate continuation. The enrollment, randomization, and completion of the study outcomes are shown in Fig. 1.
According to the results of the present study, there was no statistically signi cant difference in age, weight, height, and gender of participants between the supplement, placebo receiving and control groups (P > 0.05). Table 2 shows the demographic characteristics of patients in the studied groups. The data are presented as means ± standard deviation; *: p-values were obtained from ANOVA test; **: P-value was obtained from chi-squire test. Figure 2 depicts the relative MiRNA-217 expression levels in L-carnitine supplemented and placebo received groups during the study. As it is shown in Fig. 2, there was a signi cant difference in the expression level of MiRNA-217 between NASH positive and negative obese patients, as the expression level was higher in NASH suffering group (P < 0.001).
The results of our study showed that there was a signi cant difference in the expression level of MiRNA-217 between L-carnitine and placebo receiving groups after the study intervention (P = 0.001); while the expression levels of this variable in two mentioned groups had no signi cant difference between the two groups before the intervention (P = 0.3). Table 3 shows the expression levels of MiRNA-217 in the Lcarnitine and placebo receiving groups during our study in compare with control group.  Table 3, intra-group changes in serum expression levels of MiRNA-217 was not signi cant in the placebo received group during the study, while there was a signi cant reduction in the mean of MiRNA-217 expression level in the L-carnitine supplemented group (P = 0.1, and < 0.001, respectively).
Finally, changes of MiRNA-217 expression levels during the study were calculated by 2 −ΔΔCT formula. In studying the mean ± standard error of the mean (SEM) of MiRNA-217 expression changes, it was 2.07 ± 0.4 in the supplemented group which was statistically different from the placebo received group (mean ± SEM: -5.6 ± 0.5, P = < 0.001). Relative MiRNA-217 expression levels in two studied group during the study are shown in Fig. 3.

Discussion
To the best of our knowledge, although previous studies demonstrated several alterations in some MicroRNAs expression levels, including MiR-21, MiR-34a, MiR-122, and MiR-451 at different stages of NAFLD disease; the present study is the rst study investigating L-carnitine supplementation effects on the expression level of MiRNA-217 in NASH suffering patients with obesity [12][13][14][15] .
Given that MiRNA-217 may affect the pathogenesis of NASH, by modulating of SIRT1 expression levels; the results of our study demonstrated an increased expression level of this MiR in the serum of NASH positive patients 8,9 . Moreover, L-carnitine supplementation reduced MiRNA-217 expression levels in participants who were assigned to the supplementation group; while MiRNA-217 expression levels in the placebo received NASH, positive obese patients didn't change during the study. Therefore, the results of the present study suggest that MiRNA-217 expression level can be considered as a noninvasive practical biomarker for diagnosis, and treatment follow-up of NASH suffering patients.
Further, the results of our study were consistent to previous studies reported bene cial effects of Lcarnitine supplementation on oxidative stress, NAFLD/NASH, and liver brosis 10,16,17 . According to previous studies, a major cause of fat accumulation and oxidative stress exacerbation in hepatic tissue, is inhibition of mitochondrial fatty acid oxidation which may be modi ed by L-carnitine supplementation 17,18 . Moreover, it is reported that L-carnitine supplementation may lead to signi cant decrease in in ammation and oxidative stress levels, elevation of caspase-2 protein expression (an anti-brotic agent), and reduction of necrosing factor (NF) κB p65 also 17 .
As it is reported in previous studies, SIRT1 expression in NAFLD-induced high-fat diet mice was signi cantly decreased 19 . SIRT1, the crucial regulator of autophagy and lipogenesis, regulates lipid homeostasis by regulating PPAR α (peroxisome proliferators activated receptor α); and hepatocytespeci c repression of SIRT1 impairs PPAR α signaling and consequently, decreases beta-oxidation of fatty acids 20 . On the other hand, Lipin1, one of SIRT1 downstream genes in which its acetylation is impaired by expression alterations of SIRT1, is a key regulator of lipid metabolism in hepatocytes and its expression was signi cantly increased in alcohol-induced NAFLD mice 21 . MiRNA-217 is an endogenous inhibitor of the SIRT1 gene, binding to the 3`-UTR region and interference with the translation and therefore expression of SIRT1 22 . In fact, MiRNA-217's deleterious effect on lipin1 and depletion of SIRT1 eventually lead to fat accumulation and alcohol-dependent steatohepatitis 23 .
Another mechanism that researchers have proposed for the function of MiRNA-217 is the effect of it through the PTEN (phosphatase and tensin homolog) gene as one of the inhibitors of AKT (Protein kinase B) gene activity; which is considered as an important gene that plays role in activating liver stellate cells (the main stimulus of liver brosis), thereby increasing the levels of MiRNA-217 will may stimulate liver brosis 24, 25 .
According to the results of this double-blind RCT, MiRNA-217 expression level may be a simple practical biomarker for NASH diagnosis and follow up; however, further long-term large population-based studies are required to nd out the exact relationships between MiRNA-217 expression levels, its determinants, and consequent genomics and epigenetics outcomes and different stages of NAFLD. The major ndings of the present study as well as important methodological points are presented as graphical abstract in Fig. 4.
Impossibility of the liver biopsy as the gold standard of NAFLD/NASH diagnosis due to its invasive modality, and not assessing of carnitine levels in the study participants were two important limitations of our study. Additionally, non-assessing of SIRT1 expression levels was another limitation of the present study.
Conclusion L-carnitine supplementation reduced MiRNA-217 expression levels in participants who were assigned to the L-carnitine supplementation group; while MiRNA-217 expression levels in the placebo received NASH, positive obese patients didn't change during 12 weeks follow up.
The results of our study highlight the importance of serum MiR-217 expression level as a candidate biomarker to be considered in NASH diagnosis and treatment approaches. However, further studies are supported the analysis and interpretation. MN, MM, and MA1 supervised the study. FR, FI, and MM participated in drafting and editing the manuscript. All authors read and approved the nal manuscript.   Relative MiR-217 expression levels in L-carnitine supplemented and placebo received groups during the study; (L-carnitine supplemented group, placebo received group).