Circulating leptin in patients with nonalcoholic fatty liver disease-related liver fibrosis: a systematic review and a meta-analysis

BACKGROUND AND AIM

Clinical data on the association between leptin levels and nonalcoholic fatty liver disease (NAFLD)-related liver fibrosis are conflicting. This meta-analysis aimed to compare circulating leptin between NAFLD patients with versus without liver fibrosis or non-NAFLD controls.

METHODS

A systematic search was conducted in PubMed, Scopus, and the Cochrane Library. Fifteen studies were included, reporting data from 964 individuals (422 NAFLD patients with fibrosis, 297 NAFLD patients without fibrosis, 245 no-NAFLD controls).

RESULTS

Leptin standardized mean difference (SMD) was higher in NAFLD patients with fibrosis (F1-F4) than in controls (SMD: 2.27; 95% confidence interval [CI]: 0.81-3.73); however, this association did not remain robust after the exclusion of studies with morbidly obese individuals. No difference was observed in leptin SMD between NAFLD patients with fibrosis and those without fibrosis (F0), and NAFLD patients without fibrosis versus controls. Heterogeneity was high (I2: 66-98%) among studies. Meta-regression analysis revealed a positive association of leptin SMD with homeostasis model assessment-insulin resistance, when comparing NAFLD patients with fibrosis versus NAFLD patients without fibrosis (beta: 0.53; 95% CI: 0.04-1.03), and a negative association of leptin SMD with age, when comparing NAFLD patients with fibrosis versus controls (beta: -0.29; 95% CI: -0.53 to -0.05).

CONCLUSION

Circulating leptin was higher in NAFLD patients with liver fibrosis than non-NAFLD controls, an association, however, attenuated after the exclusion of a study with morbidly obese individuals. Circulating leptin was not different between NAFLD patients with and without fibrosis, or NAFLD patients without fibrosis and controls.

Circulating Ferritin in Patients with Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

Objectives

To synthesize data on circulating ferritin between patients with histologically confirmed nonalcoholic fatty liver disease (NAFLD) and non-NAFLD controls.

Methods

A systematic literature search was conducted in PubMed, Scopus, and the Cochrane Library. Thirty-one studies comprising data on 5631 individuals (2929 biopsy-proven NAFLD patients and 2702 controls) were included in the meta-analysis.

Results

Higher circulating ferritin levels were observed in NAFLD patients than in controls [standardized mean difference (SMD) 1.14; 95% confidence interval (95% CI) 0.73-1.55], in patients with simple nonalcoholic fatty liver (NAFL) than in controls (SMD 0.57; 95% CI 0.34-0.80), in patients with nonalcoholic steatohepatitis (NASH) than in controls (SMD 0.95; 95% CI 0.69-1.22), and in NASH than in NAFL patients (SMD 0.62; 95% CI 0.25-0.99). There was moderate-to-high heterogeneity among studies in the above pairs of comparisons (I2 = 68-97%); no risk of publication bias was observed by Egger's test (P = 0.81, P = 0.72, P = 0.59, P = 0.42, respectively). The heterogeneity was reduced in the subgroup of biopsy-proven controls in all pairs of comparisons (I2 = 0-65%). The heterogeneity was also reduced after excluding studies with the Newcastle-Ottawa Scale (NOS) score <7 (n = 10) for the comparison of NAFLD patients vs. controls (I2 = 54%, P = 0.02). The meta-regression analysis revealed that the male ratio was positively associated with ferritin SMD in the comparison between NAFLD patients and controls and accounted for 32.7% (P = 0.002) of the heterogeneity in this pair of comparison.

Conclusions

Circulating ferritin was higher in NAFLD (or NAFL or NASH) patients compared with controls. Higher levels of circulating ferritin were also associated with the severity of the disease, which, however, should be cautiously interpreted.PROSPERO registration ID: CRD42022354025.

Partial validation of a six-month high-fat diet and fructose-glucose drink combination as a mouse model of nonalcoholic fatty liver disease

PURPOSE

The need to investigate the pathogenesis and treatment of nonalcoholic fatty liver disease (NAFLD) has led to the development of multiple mouse models. The aim of this study was to validate a fast food diet (FFD) mouse model that is introduced as being close to the human disease.

METHODS

Eight to nine weeks old male and female C57BL/6 J mice were randomly allocated to a FFD group or to a chow diet (CD) group. Every four weeks, mice were weighed, and blood samples were collected for the measurement of glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglycerides (TGs) and total cholesterol. After 25 weeks, mice were sacrificed, and liver tissue was histologically evaluated.

RESULTS

FFD mice gained more weight (p = 0.049) and presented a higher liver-to-body weight ratio (p < 0.001) compared to CD mice. FFD group presented with greater steatosis, hepatocellular ballooning and NAFLD activity score (NAS), whereas lobular inflammation and fibrosis were not significantly different compared to CD. When stratified by sex, NAS was different between FFD and CD groups in both male and female mice. Group by time interaction was significant for weight, ALT and cholesterol, but not for glucose, AST and TGs.

CONCLUSION

FFD mice presented with morphologic and biochemical features of NAFLD and with greater hepatic steatosis, hepatocellular ballooning and NAS, but not lobular inflammation and fibrosis, compared to CD mice. These results only partly validate the FFD mouse model for NAFLD, at least for a 6-month feeding period.

An association study of the PNPLA3 I148M polymorphism (rs738409) with serum lipids in patients with dyslipidemia

Aim: One single nucleotide polymorphism (SNP) rs738409 in the patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene has been considered a major genetic risk factor of nonalcoholic fatty liver disease (NAFLD). Data have indicated that NAFLD is related to insulin resistance and dyslipidemia, but whether rs738409 is associated with circulating lipid and lipoproteins is not fully elucidated. The main aim of this study was to assess the association of rs738409 with lipid and lipoprotein levels in patients with dyslipidemia. Methods: This was a post-hoc analysis of a study in patients with dyslipidemia recruited on an outpatient basis. Morning blood samples were collected after a 12-h fast. Genomic DNA was extracted from whole-blood samples. Results: One hundred seventy-five patients with dyslipidemia were included (97 women). Lipid levels [total cholesterol (TC), triglycerides (TGs), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C)] or glycosylated hemoglobin (HbA1c) were not associated with the SNP, even after adjustment for gender, body mass index (BMI) and type 2 diabetes mellitus (T2DM), using either the additive (CC vs. CG vs. GG) or the dominant (CC vs. GG + CG) inheritance model. When data were stratified for obesity, significant associations between the variant and TC (P = 0.014) or LDL-C levels (P = 0.046) in the non-obese were observed. Pairwise comparison revealed significant changes only in TC between CC and CG genotypes (P = 0.012). Conclusions: No association was shown between rs738409 SNP and lipid/lipoprotein levels in patients with dyslipidemia. In subgroup analysis, TC was higher in non-obese, but not in obese, patients with CC, compared to CG carriers.

Circulating adiponectin in patients with nonalcoholic fatty liver disease-related liver fibrosis: A systematic review and a meta-analysis

BACKGROUND AND AIM

There are conflicting data on adiponectin concentrations in nonalcoholic fatty liver disease (NAFLD). The main aim was to compare circulating total adiponectin concentrations in NAFLD patients with versus without liver fibrosis.

METHODS

A systematic search was performed in PubMed, Scopus, and Cochrane Library. Twenty-two studies comprising 1753 biopsy-proven NAFLD individuals (1290 with and 463 without fibrosis) were included in the meta-analysis.

RESULTS

There was no difference in adiponectin concentration between NAFLD patients with versus without fibrosis (standardized mean difference [SMD]: -0.15; 95% confidence interval [95% CI]: -0.35 to 0.05). Heterogeneity was moderate among studies (Ι² : 60%, P < 0.001); no risk of publication bias was observed (Egger's test; P = 0.37). The sensitivity analysis, performed after the exclusion of studies with (i) children/adolescents and morbidly obese patients (n = 3) and (ii) adiponectin measurement with other methods than enzyme-linked immunosorbent assay (ELISA) (n = 9), revealed significantly lower adiponectin concentrations in NAFLD patients with fibrosis (i) SMD: -0.23, 95% CI: -0.41 to -0.04; (ii) SMD: -0.30, 95% CI: -0.55 to -0.04, respectively). Meta-regression analysis revealed no significant association of adiponectin SMD with age, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl-transferase, homeostasis model assessment insulin resistance and the proportion of men.

CONCLUSIONS

Overall, patients with NAFLD and fibrosis had similar adiponectin concentrations with patients with NAFLD without fibrosis. However, adiponectin concentration was lower in NAFLD patients with fibrosis than those without fibrosis within the adult patients without morbid obesity and in studies in which adiponectin was measured with the same method (ELISA).

Sodium-glucose co-transporter 2 inhibitors in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is considered the most prevalent chronic hepatic disease, as it has been estimated that one of four individuals in the general population has been affected by NAFLD. The evolution of the referred entity, which includes nonalcoholic steatohepatitis (NASH) and hepatic fibrosis, may have crucial and even fatal consequences, leading to cirrhosis and hepatocellular carcinoma. Although NAFLD has also been linked with cardiovascular and renal diseases, and all-cause mortality increment, pharmacological therapy is as yet an unfulfilled demand. Since NAFLD is closely associated with type 2 diabetes mellitus (T2DM), a variety of anti-diabetic drugs have been investigated for their effectiveness towards NAFLD. Sodium-glucose co-transporter 2 inhibitors (SGLT-2i) improve blood glucose levels through increasing renal glucose excretion and they are recommended as one of standard therapeutic categories for T2DM patients. Based on preclinical animal studies, SGLT-2i have shown a beneficial effect on NAFLD, inducing histologically proven amelioration of hepatic steatosis, inflammation and fibrosis. Promising data have been also derived by clinical trials, which have indicated a potentially beneficial effect of SGLT-2i on NAFLD, at least in terms of liver function tests and imaging. Thus, it is not strange that there are many ongoing trials on the effect of various SGLT-2i in NAFLD. In conclusion, current evidence concerning the effect of SGLT-2i on NAFLD is encouraging; however, data from ongoing clinical trials with histological endpoints are awaited.