Adipokine Levels Versus Hepatic Histopathology in Bariatric Surgery Patients

Network Pharmacology to Reveal the Molecular Mechanisms of Rutaceous Plant-derived Limonin Ameliorating Non-alcoholic Steatohepatitis

BACKGROUND

Limonin shows promise in alleviating non-alcoholic fatty liver disease. We investigated the mechanisms of limonin against non-alcoholic steatohepatitis (NASH) using network pharmacology and molecular docking.

METHODS

Public databases provided NASH- and limonin-associated targets. VennDiagram identified potential limonin targets for NASH. Enrichment analysis explored the limonin-NASH relationship. PPI network analysis, CytoHubba models, and bioinformatics identified hub genes for NASH treatment. Molecular docking assessed limonin's binding ability to hub targets.

RESULTS

We found 37 potential limonin targets in NASH, involved in oxidative stress, inflammation, and signaling pathways. PPI network analysis revealed seven hub genes (STAT3, NFKBIA, MTOR, TLR4, CASP8, PTGS2, NFKB1) as NASH treatment targets. Molecular docking confirmed limonin's binding to STAT3, CASP8, and PTGS2. Animal experiments on high-fat diet mice showed limonin reduced hepatic steatosis, lipid accumulation, and expression of p-STAT3/STAT3, CASP8, and PTGS2.

CONCLUSION

Limonin's therapeutic effects in NASH may stem from its antioxidant and anti-inflammatory properties. STAT3, CASP8, and PTGS2 are potential key targets for NASH treatment, warranting further investigation.

Associations between subcutaneous adipocyte hypertrophy and nonalcoholic fatty liver disease

Adipocyte hypertrophy and expression of adipokines in subcutaneous adipose tissue (SAT) have been linked to steatosis, nonalcoholic steatohepatitis (NASH) and fibrosis in morbidly obese (BMI ≥ 40 kg/m²) subjects. It is unknown if this is also true for subjects with NAFLD with lesser degrees of obesity (BMI < 35 kg/m²). Thirty-two subjects with biopsy-proven NAFLD and 15 non-diabetic controls matched for BMI underwent fine-needle biopsies of SAT. Adipocyte volume was calculated. RNA-sequencing of SAT was performed in a subset of 20 NAFLD patients. Adipocyte volume and gene expression levels were correlated to the presence of NASH or significant fibrosis. Subjects with NAFLD had larger adipocyte volume compared with controls, (1939 pL, 95% CI 1130-1662 vs. 854 pL, 95% CI 781-926, p < 0.001). There was no association between adipocyte volume and the presence of NASH. Gene expression of adipokines previously described to correlate with NASH in morbid obesity, was not associated with NASH or fibrosis. Our results suggest that persons with NAFLD have larger SAT adipocytes compared with controls and that adipocytes are involved in the pathophysiology of hepatic steatosis in NAFLD. However, adipocyte volume was not associated with NASH or fibrosis in NAFLD subjects with varying degrees of obesity.

Contribution of organokines in the development of NAFLD/NASH associated hepatocellular carcinoma

Globally the incidence of hepatocellular carcinoma (HCC) is on an upsurge. Evidence is accumulating that liver disorders like nonalcoholic fatty liver disease (NAFLD) and its more progressive form nonalcoholic steatohepatitis (NASH) are associated with increased risk of developing HCC. NAFLD has a prevalence of about 25% and 50%-90% in obese population. With the growing burden of obesity epidemic worldwide, HCC presents a major healthcare burden. While cirrhosis is one of the major risk factors of HCC, available literature suggests that NAFLD/NASH associated HCC also develops in minimum or noncirrhotic livers. Therefore, there is an urgent need to understand the pathogenesis and risk factors associated with NAFLD and NASH related HCC that would help in early diagnosis and favorable prognosis of HCC secondary to NAFLD. Adipokines, hepatokines and myokines are factors secreted by adipocytes, hepatocytes and myocytes, respectively, playing essential roles in cellular homeostasis, energy balance and metabolism with autocrine, paracrine and endocrine effects. In this review, we endeavor to focus on the role of these organokines in the pathogenesis of NAFLD/NASH and its progression to HCC to augment the understanding of the factors stimulating hepatocytes to acquire a malignant phenotype. This shall aid in the development of novel therapeutic strategies and tools for early diagnosis of NAFLD/NASH and HCC.

Decoding the Pathophysiology of Non-alcoholic Fatty Liver Disease Progressing to Non-alcoholic Steatohepatitis: A Systematic Review

Non-alcoholic fatty liver disease (NAFLD) is the most common hepatic manifestation of metabolic syndromes, and its roots are strongly associated with obesity and insulin resistance. The excess fat induces inflammatory pathways by tissue irritation and progresses to non-alcoholic steatohepatitis (NASH), fibrosis, and has emerged as the most frequent cause of hepatocellular cancer (HCC). This systematic review was structured per the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The evidence was obtained from 13 research articles published in PubMed, Google Scholar, and Science Direct databases, including cross-sectional, case-control, prospective cohort studies, meta-analysis, and systematic reviews. The inclusion/exclusion criteria of free articles, published in English involving humans of mid-age in the last five years were applied. This review highlights findings in 7781 individuals, including non-NAFLD, NAFLD, and NASH positive individuals based on anthropometric measurement, blood samples, FibroScan, flow cytometry, and liver biopsy. The results underscored that the onset of inflammation set on the background of NAFLD starts NASH; the understanding and control of inflammation will help us design definitive biomarkers and treatment modalities. The complex pathogenesis and comparatively slow advancement but high morbidity have led investigators to understand the nuts and bolts for early management and prevention. Lipotoxicity and dysbiosis stimulate the immune system to generate cytokines and chemokines and decline in adipokines. The role of proteinase3 (PR3) and antitrypsin (ATT) ratio and biliverdin reductase (BVR) compel the exploration for non-invasive tests for definitive therapy.

Serum Resistin Levels in Adult Patients with Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

Previous studies reported that serum resistin levels were remarkably changed in patients with nonalcoholic fatty liver disease (NAFLD) but the conclusions were inconsistent. The aim of this study was to investigate accurate serum resistin levels in adult patients with NAFLD.

METHODS

A complete literature research was conducted in the PubMed, Embase, and Cochrane Library databases, and all the available studies up to 7 May 2020 were reviewed. The pooled standardized mean difference (SMD) values were calculated to investigate the serum resistin levels in patients with NAFLD and healthy controls.

RESULTS

A total of 28 studies were included to investigate the serum resistin levels in patients with NAFLD. Patients with NAFLD had higher serum resistin levels than controls (SMD=0.522, 95% confidence interval [CI]: 0.004-1.040, I ²=95.9%). Patients with nonalcoholic steatohepatitis (NASH) had lower serum resistin levels than the healthy controls (SMD=-0.44, 95% CI: -0.83-0.55, I ²=74.5%). In addition, no significant difference of serum resistin levels was observed between patients with NAFL and healthy controls (SMD=-0.34, 95% CI: -0.91-0.23, I ²=79.6%) and between patients with NAFL and NASH (SMD=0.15, 95% CI: -0.06-0.36, I ²=0.00%). Furthermore, subgroup and sensitivity analyses suggested that heterogeneity did not affect the results of meta-analysis.

CONCLUSIONS

This meta-analysis investigated the serum resistin levels in adult patients with NAFLD comprehensively. Patients with NAFLD had higher serum resistin levels and patients with NASH had lower serum resistin levels than healthy controls. Serum resistin could serve as a potential biomarker to predict the development risk of NAFLD.

Hepatokines and adipokines in NASH-related hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) is increasing in industrialised societies; this is likely secondary to the increasing burden of non-alcoholic fatty liver disease (NAFLD), its progressive form non-alcoholic steatohepatitis (NASH), and the metabolic syndrome. Cumulative studies suggest that NAFLD-related HCC may also develop in non-cirrhotic livers. However, prognosis and survival do not differ between NAFLD- or virus-associated HCC. Thus, research has increasingly focused on NAFLD-related risk factors to better understand the biology of hepatocarcinogenesis and to develop new diagnostic, preventive, and therapeutic strategies. One important aspect thereof is the role of hepatokines and adipokines in NAFLD/NASH-related HCC. In this review, we compile current data supporting the use of hepatokines and adipokines as potential markers of disease progression in NAFLD or as early markers of NAFLD-related HCC. While much work must be done to elucidate the mechanisms and interactions underlying alterations to hepatokines and adipokines, current data support the possible utility of these factors - in particular, angiopoietin-like proteins, fibroblast growth factors, and apelin - for detection or even as therapeutic targets in NAFLD-related HCC.

Dim Light at Night Disturbs Molecular Pathways of Lipid Metabolism

Dim light at night (dLAN) is associated with metabolic risk but the specific effects on lipid metabolism have only been evaluated to a limited extent. Therefore, to explore whether dLAN can compromise lipid metabolic homeostasis in healthy individuals, we exposed Wistar rats to dLAN (~2 lx) for 2 and 5 weeks and analyzed the main lipogenic pathways in the liver and epididymal fat pad, including the control mechanisms at the hormonal and molecular level. We found that dLAN promoted hepatic triacylglycerol accumulation, upregulated hepatic genes involved in de novo synthesis of fatty acids, and elevated glucose and fatty acid uptake. These observations were paralleled with suppressed fatty acid synthesis in the adipose tissue and altered plasma adipokine levels, indicating disturbed adipocyte metabolic function with a potential negative impact on liver metabolism. Moreover, dLAN-exposed rats displayed an elevated expression of two peroxisome proliferator-activated receptor family members (Pparα and Pparγ) in the liver and adipose tissue, suggesting the deregulation of important metabolic transcription factors. Together, our results demonstrate that an impaired balance of lipid biosynthetic pathways caused by dLAN can increase lipid storage in the liver, thereby accounting for a potential linking mechanism between dLAN and metabolic diseases.

Hepatocyte Injury and Hepatic Stem Cell Niche in the Progression of Non-Alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease characterized by lipid accumulation in hepatocytes in the absence of excessive alcohol consumption. The global prevalence of NAFLD is constantly increasing. NAFLD is a disease spectrum comprising distinct stages with different prognoses. Non-alcoholic steatohepatitis (NASH) is a progressive condition, characterized by liver inflammation and hepatocyte ballooning, with or without fibrosis. The natural history of NAFLD is negatively influenced by NASH onset and by the progression towards advanced fibrosis. Pathogenetic mechanisms and cellular interactions leading to NASH and fibrosis involve hepatocytes, liver macrophages, myofibroblast cell subpopulations, and the resident progenitor cell niche. These cells are implied in the regenerative trajectories following liver injury, and impairment or perturbation of these mechanisms could lead to NASH and fibrosis. Recent evidence underlines the contribution of extra-hepatic organs/tissues (e.g., gut, adipose tissue) in influencing NASH development by interacting with hepatic cells through various molecular pathways. The present review aims to summarize the role of hepatic parenchymal and non-parenchymal cells, their mutual influence, and the possible interactions with extra-hepatic tissues and organs in the pathogenesis of NAFLD.

The Contribution of the Adipose Tissue-Liver Axis in Pediatric Patients with Nonalcoholic Fatty Liver Disease after Laparoscopic Sleeve Gastrectomy

OBJECTIVE

To evaluate the histopathologic modifications in liver and visceral adipose tissue (VAT), and to correlate these changes with clinical measures, adipokine production, and proinflammatory cytokines in a population of adolescents with obesity with nonalcoholic fatty liver disease (NAFLD) who underwent laparoscopic sleeve gastrectomy (LSG).

STUDY DESIGN

Twenty adolescents with obesity who underwent LSG and with biopsy-proven NAFLD were included. Patients underwent clinical evaluation and blood tests at baseline and 1 year after the surgical procedure. Liver and VAT specimens were processed for routine histology, immunohistochemistry, and immunofluorescence.

RESULTS

In adolescents with obesity and NAFLD, hepatic histologic alterations were uncorrelated with VAT inflammation. LSG induced in both liver and VAT tissue histopathology amelioration and macrophage profile modification that were correlated with body mass index and improvement in insulin resistance. The adipokine profile in liver and VAT was associated with weight loss and histologic improvement after LSG. Serum proinflammatory cytokines were correlated with liver and VAT histopathology and IL-1β and IL-6 levels were independently predicted by liver necroinflammatory grade.

CONCLUSIONS

This study suggests a unique adipose tissue/fatty liver crosstalk in pediatric patients. LSG induces a similar pattern of histologic improvement in the liver and in VAT. Besides VAT, our results strengthen the role of the liver in adipocytokine production and its contribution to systemic inflammation in pediatric patients with NAFLD.

Recent Insights into the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem worldwide and an important risk factor for both hepatic and cardiometabolic mortality. The rapidly increasing prevalence of this disease and of its aggressive form nonalcoholic steatohepatitis (NASH) will require novel therapeutic approaches based on a profound understanding of its pathogenesis to halt disease progression to advanced fibrosis or cirrhosis and cancer. The pathogenesis of NAFLD involves a complex interaction among environmental factors (i.e., Western diet), obesity, changes in microbiota, and predisposing genetic variants resulting in a disturbed lipid homeostasis and an excessive accumulation of triglycerides and other lipid species in hepatocytes. Insulin resistance is a central mechanism that leads to lipotoxicity, endoplasmic reticulum stress, disturbed autophagy, and, ultimately, hepatocyte injury and death that triggers hepatic inflammation, hepatic stellate cell activation, and progressive fibrogenesis, thus driving disease progression. In the present review, we summarize the currently available data on the pathogenesis of NAFLD, emphasizing the most recent advances. A better understanding of NAFLD/NASH pathogenesis is crucial for the design of new and efficient therapeutic interventions.

CORRELATION BETWEEN NONALCOHOLIC FATTY LIVER DISEASE FEATURES AND LEVELS OF ADIPOKINES AND INFLAMMATORY CYTOKINES AMONG MORBIDLY OBESE INDIVIDUALS

ABSTRACT BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the commonest hepatopathy worldwide. OBJECTIVE: To investigate the correlations between NAFLD histopathological features and the levels of adipokines (adiponectin, leptin, and resistin) and circulating inflammatory markers (interleukin-6 [IL-6], interleukin-8 [IL-8], tumor necrosis factor alpha [TNF-α], and C-reactive protein [CRP]). METHODS: This is an exploratory cross-sectional study, which enrolled 19 women with obesity who underwent bariatric surgery. Biochemical characteristics evaluated included the levels of adiponectin, leptin, resistin, IL-6, IL-8, TNF-α, and CRP. NAFLD was assessed through histological examination of liver biopsies carried out during the surgical procedures. RESULTS: The mean age of the study group was 37.3±8.2 years old; mean BMI was 36.2±2.5 kg/m2. Among individuals with liver fibrosis, the levels of IL-8 were significantly higher (24.4 ± 9.7 versus 12.7 ± 6.6; P=0.016726). The intensity of fibrosis presented a significant negative correlation with the levels of adiponectin (R= -0.49379; P=0.03166); i.e. the higher the levels of adiponectin, the lower the intensity of fibrosis. The intensity of steatohepatitis presented a significant negative correlation with the levels of adiponectin (R= -0.562321; P=0.01221); this means that the higher the levels of adiponectin, the lower the intensity of steatohepatitis. CONCLUSION: Adiponectin levels were inversely correlated with the severity of fibrosis and steatohepatitis, whereas IL-8 levels were higher in individuals with liver fibrosis among individuals with obesity and NAFLD undergoing bariatric surgery. The use of these markers to assess NAFLD may bring significant information within similar populations.

Laparoscopic Sleeve Gastrectomy Improves Nonalcoholic Fatty Liver Disease-Related Liver Damage in Adolescents by Reshaping Cellular Interactions and Hepatic Adipocytokine Production

OBJECTIVES

To investigate whether the modulation of local cellular cross-talks and the modification of hepatic adipocytokine expression could mechanistically explain the improvement of liver histopathology after laparoscopic sleeve gastrectomy (LSG) in adolescents with nonalcoholic fatty liver disease (NAFLD).

STUDY DESIGN

Twenty obese (body mass index of ≥35 kg/m²) adolescents who underwent LSG and with biopsy-proven NAFLD were included. At baseline (T0) and 1 year after treatment, patients underwent clinical evaluation, blood tests, and liver biopsy. Hepatic progenitor cells, hepatic stellate cells (HSCs), macrophages, and adipocytokines were evaluated by immunohistochemistry and immunofluorescence.

RESULTS

Liver biopsy samples after LSG demonstrated a significant improvement of NAFLD Activity Score and fibrosis. Immunohistochemistry indicated a significant reduction of hepatocyte cell cycle arrest, ductular reaction, activated HSC, and macrophage number after LSG compared with T0. The activation state of HSC was accompanied by modification in the expression of the autophagy marker LC3. Hepatocyte expression of adiponectin was significant higher after LSG than into T0. Moreover, LSG caused decreased resistin expression in Sox9⁺ hepatic progenitor cells compared with T0. The number of S100A9⁺ macrophages was also reduced by LSG correlating with resistin expression. Finally, serum levels of proinflammatory cytokines significantly correlated with macrophages and activated HSC numbers.

CONCLUSIONS

The histologic improvement induced by LSG is associated with the reduced activation of local cellular compartments (hepatic progenitor cells, HSCs, and macrophages), thus, strengthening the role of cellular interactions and hepatic adipocytokine production in the pathogenesis of NAFLD.

Deciphering the Relationship between Obesity and Various Diseases from a Network Perspective

The number of obesity cases is rapidly increasing in developed and developing countries, thereby causing significant health problems worldwide. The pathologic factors of obesity at the molecular level are not fully characterized, although the imbalance between energy intake and consumption is widely recognized as the main reason for fat accumulation. Previous studies reported that obesity can be caused by the dysfunction of genes associated with other diseases, such as myocardial infarction, hence providing new insights into dissecting the pathogenesis of obesity by investigating its associations with other diseases. In this study, we investigated the relationship between obesity and diseases from Online Mendelian Inheritance in Man (OMIM) databases on the protein–protein interaction (PPI) network. The obesity genes and genes of one OMIM disease were mapped onto the network, and the interaction scores between the two gene sets were investigated on the basis of the PPI of individual gene pairs, thereby inferring the relationship between obesity and this disease. Results suggested that diseases related to nutrition and endocrine are the top two diseases that are closely associated with obesity. This finding is consistent with our general knowledge and indicates the reliability of our obtained results. Moreover, we inferred that diseases related to psychiatric factors and bone may also be highly related to obesity because the two diseases followed the diseases related to nutrition and endocrine according to our results. Numerous obesity–disease associations were identified in the literature to confirm the relationships between obesity and the aforementioned four diseases. These new results may help understand the underlying molecular mechanisms of obesity–disease co-occurrence and provide useful insights for disease prevention and intervention.

Obstructive sleep apnea: Influence of hypertension on adiponectin, inflammatory markers and dyslipidemia

Obstructive sleep apnea (OSA) is a common but often unrecognized condition with potentially serious complications. The aim of this study was to explore the possible mechanisms linking hypertension (HT), a common cardiovascular disease (CVD), with obstructive sleep apnea (OSA) by investigating the levels of morning and evening serum adiponectin, inflammatory markers (TNF-α, IL-6), and lipid profiles in OSA patients with and without HT. Four groups were enrolled in this case-control analytic study: control, OSA, OSA+HT, and HT groups, each of which included 22 subjects. The results revealed low morning and evening serum adiponectin levels in patients with OSA and OSA+HT compared with their control and HT counterparts. Serum adiponectin levels declined progressively with increasing severity of OSA. Also, morning adiponectin levels were significantly decreased at the same time that a loss of the normal diurnal rhythm was observed in the OSA and OSA+HT groups. Both TNF-α and IL-6 levels were significantly increased in the OSA and OSA+HT groups compared with levels in the control and HT groups. Altered lipid profiles was noticed in the same groups. These findings were more pronounced in the OSA+HT than in the OSA group. In conclusion, the biochemical findings of this study demonstrate predominantly low adiponectin levels, increased levels of inflammatory markers, and atherogenic lipid profiles in OSA patients with HT compared with those of the other patients studied. This highlights the possible contributing role of these factors to the pathogenesis of HT as a common cardiovascular complication in OSA patients.

Adipokines and Non-Alcoholic Fatty Liver Disease: Multiple Interactions

Accumulating evidence links obesity with low-grade inflammation which may originate from adipose tissue that secretes a plethora of pro- and anti-inflammatory cytokines termed adipokines. Adiponectin and leptin have evolved as crucial signals in many obesity-related pathologies including non-alcoholic fatty liver disease (NAFLD). Whereas adiponectin deficiency might be critically involved in the pro-inflammatory state associated with obesity and related disorders, overproduction of leptin, a rather pro-inflammatory mediator, is considered of equal relevance. An imbalanced adipokine profile in obesity consecutively contributes to metabolic inflammation in NAFLD, which is associated with a substantial risk for developing hepatocellular carcinoma (HCC) also in the non-cirrhotic stage of disease. Both adiponectin and leptin have been related to liver tumorigenesis especially in preclinical models. This review covers recent advances in our understanding of some adipokines in NAFLD and associated HCC.