The macrophage activation marker sCD163 is associated with changes in NAFLD and metabolic profile during lifestyle intervention in obese children

Converted Macrophage Polarization and Expression of COL6α3-Early Predictors of Remodeling Processes in Adipose Tissue of Male Children

Background/Objectives: Overweight and obesity in early childhood is a serious public health problem as in most cases it persists into adulthood and significantly affects the quality of life. The aim of this study was to investigate the mechanisms that trigger extracellular matrix (ECM) remodeling in the subcutaneous (SAT) and visceral (VAT) adipose tissue of male children in relation to their body weight. Methods: During elective abdominal surgery, SAT and VAT were acquired from 75 male subjects undergoing hernia repair (inguinal herniorrhaphy by Ferguson) or orchidopexy. Based on their Z-score, subjects were separated into two groups. The morphometry of both adipose tissue compartments was assessed after hematoxylin and eosin histological staining, immunohistochemistry to quantify CD163+ cells and the number of crown-like structures (CLSs), and real-time polymerase chain reaction to assess the relative gene expression for collagen VI subtype alpha 3 (COL6α3). Results: Obese and overweight individuals were found to have higher numbers of CD163+ cells, greater numbers of CLSs in VAT and SAT, and a higher expression of COL6α3 in both compartments. Conclusions: Obesity in childhood may lead to increased COL6α3 gene expression and promote the activation of macrophage polarization, compromise the structural integrity of the ECM, and thus influence the development of inflammatory processes.

Use of Biomarkers in Nutrition Intervention Studies of Children: A Scoping Review

Obesity in youth is an increasingly prevalent public health concern worldwide. Lifestyle interventions aim to help participants establish healthy habits and reduce obesity-related disease risk by targeting physical activity and dietary habits. Most studies assess weight loss, but biomarkers may enable more rapid and comprehensive assessment of intervention success. This scoping review aims to synthesize the published literature on which biomarkers are assessed during interventions for pediatric obesity to inform future use. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search of five databases conducted in February 2022 returned 1579 unique and relevant articles published between 2006 and 2021. After screening titles, abstracts, and full text, four reviewers determined that 43 studies met eligibility requirements. Quality screening was conducted, and 97.7% of papers were of fair or good quality. Of the 43 studies, 47% reported measures of adipose-related signaling molecules inclusive of adipokines, 74% included insulin-related biomarkers, 63% reported lipid-related biomarkers, 40% reported proinflammatory cytokine biomarkers, 12% reported measures of skin and/or plasma carotenoids, 40% measured blood pressure, and 21% included liver enzymes. Sixty-seven percent of studies measured biomarkers in whole blood, 40% measured biomarkers in plasma, 56% measured biomarkers in serum, and 2% measured biomarkers in urine. This work summarizes the current use of biomarkers in lifestyle intervention studies enrolling children. These biomarkers could be clinically relevant for pediatric weight management interventions.

Identification of common signature genes and pathways underlying the pathogenesis association between nonalcoholic fatty liver disease and heart failure

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and heart failure (HF) are related conditions with an increasing incidence. However, the mechanism underlying their association remains unclear. This study aimed to explore the shared pathogenic mechanisms and common biomarkers of NAFLD and HF through bioinformatics analyses and experimental validation.

METHODS

NAFLD and HF-related transcriptome data were extracted from the Gene Expression Omnibus (GEO) database (GSE126848 and GSE26887). Differential analysis was performed to identify common differentially expressed genes (co-DEGs) between NAFLD and HF. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) were conducted to explore the functions and regulatory pathways of co-DEGs. Protein-protein interaction (PPI) network and support vector machine-recursive feature elimination (SVM-RFE) methods were used to screen common key DEGs. The diagnostic value of common key DEGs was assessed by receiver operating characteristic (ROC) curve and validated with external datasets (GSE89632 and GSE57345). Finally, the expression of biomarkers was validated in mouse models.

RESULTS

A total of 161 co-DEGs were screened out in NAFLD and HF patients. GO, KEGG, and GSEA analyses indicated that these co-DEGs were mainly enriched in immune-related pathways. PPI network revealed 14 key DEGs, and SVM-RFE model eventually identified two genes (CD163 and CCR1) as common key DEGs for NAFLD and HF. Expression analysis revealed that the expression levels of CD163 and CCR1 were significantly down-regulated in HF and NAFLD patients. ROC curve analysis showed that CD163 and CCR1 had good diagnostic values for HF and NAFLD. Single-gene GSEA suggested that CD163 and CCR1 were mainly engaged in immune responses and inflammation. Experimental validation indicated unbalanced macrophage polarization in HF and NAFLD mouse models, and the expression of CD163 and CCR1 were significantly down-regulated.

CONCLUSION

This study identified M2 polarization impairment characterized by decreased expression of CD163 and CCR1 as a common pathogenic pathway in NAFLD and HF. The downregulation of CD163 and CCR1 may reflect key pathological changes in the development and progression of NAFLD and HF, suggesting their potential as diagnostic and therapeutic targets.

Macrophage metabolism impacts metabolic dysfunction-associated steatotic liver disease and its progression

Metabolic dysfunction-associated steatotic liver disease (MASLD), with a progressive form of metabolic dysfunction-associated steatohepatitis (MASH), is the leading chronic liver disease worldwide, which can progress to advanced liver disease and hepatocellular carcinoma. MASLD is tightly associated with metabolic disorders such as obesity, insulin resistance, and type 2 diabetes. Macrophages, as an innate immune component and a linker of adaptive immune response, play important roles in the pathogenesis and treatment of MASLD or MASH. Metabolic reprogramming can regulate macrophage activation and polarization to inhibit MASLD or MASH progression to advanced liver disease. Here, we summarize the underlying mechanisms of how different metabolites such as amino acids, glucose, and fatty acids can regulate macrophage function and phenotype, the factors that regulate macrophage metabolism, and potential treatment options to regulate macrophage function in MASLD or MASH, as well as other associated metabolic disorders.

Uric acid and sCD163 as biomarkers for metabolic dysfunction and MAFLD in children and adolescents with overweight and obesity

OBJECTIVES

The prevalence of childhood obesity increases globally, and noninvasive methods are needed to identify metabolic dysfunction and obesity-related complications such as pediatric metabolic associated fatty liver disease (MAFLD). We investigated whether uric acid (UA) and the macrophage marker soluble form of cysteine scavenger receptor CD163 (sCD163) can be used as biomarkers for deteriorated metabolism or pediatric MAFLD in children with overweight or obesity.

METHODS

Cross-sectional clinical and biochemical data from 94 children with overweight or obesity was included. Surrogate liver markers were calculated, and correlations were investigated using Pearson's or Spearman's correlation test.

RESULTS

UA and sCD163 correlated with BMI standard deviation score (r=0.23, p<0.05; r=0.33, p<0.01) and body fat (r=0.24, p<0.05; r=0.27, p=0.01). UA correlated with triglycerides (ρ=0.21, p<0.05), fat free mass (r=0.33, p<0.01), and gamma-glutamyl transferase (r=0.39, p<0.01). sCD163 correlated with the pediatric NAFLD fibrosis score (r=0.28, p<0.01) and alanine aminotransferase (r=0.28, p<0.01). No correlation was found between UA and pediatric MAFLD.

CONCLUSIONS

UA and sCD163 was identified as markers of a deranged metabolic profile, thus acting as easily accessible biomarkers for obesity and an obesity-related deranged metabolism. Furthermore, increasing levels of sCD163 could be a useful biomarker of pediatric MAFLD. Future prospective studies are warranted.

Soluble CD163 is a predictor of fibrosis and hepatocellular carcinoma development in nonalcoholic steatohepatitis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. The serum level of soluble CD163 (sCD163), a macrophage activation marker, is associated with liver tissue changes; however, its prognostic value is unknown. Here, we determined the utility of sCD163 as a marker for hepatocellular carcinoma (HCC) and prognostic marker for NAFLD.

METHODS

This retrospective study obtained data regarding serum sCD163 levels, liver histology, and background factors associated with NAFLD in 287 patients (men/women, 140/147; average age, 53 ± 14 years) with NAFLD who underwent liver biopsy. Repeated liver biopsies of 287 patients with NAFLD (5.0 ± 2.7 years) were compared regarding serum sCD163 levels and liver tissue changes (stage, grade, steatosis, and NAFLD activity score).

RESULTS

Serum sCD163 levels increased with the progression of liver fibrosis and inflammation (both P < 0.05) and were particularly helpful in distinguishing cases of Grade 4 fibrosis (P < 0.001). Levels of sCD163 significantly decreased in patients with NAFLD exhibiting alleviated fibrosis and inflammation (P < 0.05). We could also predict the development of HCC and associated mortality based on serum sCD163 levels at the time of NAFLD diagnosis. Serum sCD163 levels were higher in patients with HCC than in patients without HCC (1074 ± 379 ng/ml vs. 669 ± 261 ng/ml; P < 0.0001), and the same trend was observed for mortality.

CONCLUSIONS

The serum sCD163 level reflects the progression of fibrosis and inflammation in liver tissues, showing much promise as a noninvasive biomarker for nonalcoholic steatohepatitis and NAFLD as well as a possible predictor of HCC development and patient prognosis.

The association between soluble CD163, disease severity, and ursodiol treatment in patients with primary biliary cholangitis

INTRODUCTION

The macrophage activation marker soluble (s)CD163 is associated with disease severity and prognosis in patients with primary biliary cholangitis (PBC). Ursodeoxycholic acid (UDCA) treatment attenuates fibrosis progression in PBC patients, but its effect on macrophage activation is unclear. We examined the effect of UDCA on macrophage activation, as determined by sCD163 levels.

METHODS

We included 2 cohorts of PBC patients; 1 cohort with prevalent PBC patients, and 1 cohort of incident PBC patients before start of UDCA treatment and with follow-up after 4 weeks and 6 months. We measured sCD163 and liver stiffness in both cohorts. Further, we measured sCD163 and TNF-α shedding in vitro in monocyte-derived macrophages after UDCA and lipopolysaccharide incubation.

RESULTS

We included 100 patients with prevalent PBC [93% women, median age 63 y (interquartile range: 51-70)] and 47 patients with incident PBC [77% women, median age 60 y (49-67)]. Prevalent PBC patients had a lower median sCD163 of 3.54 mg/L (2.77-4.72) than incident PBC patients with a median sCD163 of 4.33 mg/L (2.83-5.99) at inclusion. Patients with an incomplete response to UDCA and patients with cirrhosis had higher sCD163 than responders to UDCA and noncirrhosis patients. After 4 weeks and 6 months of UDCA treatment median sCD163 decreased by 4.6% and 9.0%, respectively. In in vitro experiments, UDCA attenuated shedding of TNF-α, but not sCD163, from monocyte-derived macrophages.

CONCLUSION

In PBC patients, sCD163 levels correlated with liver disease severity and treatment response to UDCA. Further, after 6 months of UDCA treatment, we observed a decrease in sCD163, which may be related to the treatment.

Obese Patients With Nonalcoholic Fatty Liver Disease Have an Increase in Soluble Plasma CD163 and a Concurrent Decrease in Hepatic Expression of CD163

Background and Aims

Macrophages play an important role in the development of nonalcoholic fatty liver disease (NAFLD) and its progression to nonalcoholic steatohepatitis (NASH). In this study, we investigated the hepatic expression of the macrophage scavenger receptor CD163 and the plasma level of its shed soluble form (sCD163) in patients with obesity and NASH, non-NASH NAFLD (NAFL), or healthy livers (no NAFLD).

Methods

Paired liver biopsies and plasma samples were collected from 61 patients with obesity (body mass index ≥35). Hepatic expression of CD163 was analyzed by immunohistochemistry and data-independent acquisition mass spectrometry, whilst plasma levels of sCD163 were determined by enzyme-linked immunosorbent assay and data-independent acquisition mass spectrometry. NAFLD stage and activity were assessed using the Kleiner fibrosis and NASH Clinical Research Network (NAS-CRN) scoring system.

Results

sCD163 turned out as a promising predictor of NASH with an area under the receiver-operating characteristic curve of 0.78 [0.65;0.92] (P = .0008). sCD163 increased with more severe NAFLD both in univariate (odds ratio [OR] = 3.31[1.80;6.11], P < .001) and multivariable ordinal logistic regression adjusting for NAFLD risk factors (OR = 2.02 [1.03;3.97], P = .042). On the other hand, hepatic expression of CD163 was negatively associated with more severe NAFLD in univariate ordinal logistic regression determined by immunohistochemistry (OR = 0.91[0.84;0.98], P = .015) and proteomics (OR = 0.13[0.02;0.80], P = .028). Taking NAFLD risk factors into account, hepatic expression of CD163 was only associated with the fibrosis stage (OR = 0.01 [0.0003;0.21], P = .004). Accordingly, hepatic CD163 surface expression and sCD163 were negatively correlated (rho = -0.478, P = .0001).

Conclusion

An increased plasma sCD163 and a concurrent decreased hepatic expression of CD163 are strongly associated with NAFLD in obese patients.

Spotlight on liver macrophages for halting injury and progression in non-alcoholic fatty liver disease

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of the metabolic syndrome and is rapidly emerging as the leading cause of liver-related morbidity and mortality. Macrophages play an essential role in the development and progression of NAFLD.

AREAS COVERED

In this review, we provide an update on recent studies of drugs, which directly or indirectly affect macrophages in NAFLD, and discuss the implication of macrophage biomarkers to monitor the disease stage and progression/regression.

EXPERT OPINION

There is an unmet need for better understanding of disease pathogenesis from hepatic fat accumulation to disease progression with inflammation and fibrosis. We expect that future research will uncover additional objects/pathways as treatment targets. We speculate that this will involve better characterization of the gut microbiome, damage-associated molecular patterns (DAMPS) or molecules and pathways involved in development of DAMPS, and advanced molecular biology studies including single-cell sequencing of macrophage subpopulations. In addition, we speculate that studies focusing on pharmaceuticals that improve insulin resistance, diminish the metabolic syndrome and reduce fibrosis will prevail.

Clinical Progression of Metabolic-Associated Fatty Liver Disease Is Rare in a Danish Tertiary Liver Center

Data concerning non-invasive discrimination of simple steatosis from steatohepatitis in metabolic-associated fatty liver disease (MAFLD) and risk of disease progression in patients with MAFLD are conflicting. We aimed to investigate these factors in an MAFLD cohort at a Danish tertiary liver centre. We retrospectively assessed 129 patients with biopsy-proven MAFLD. Patients were divided according to the presence of simple steatosis or steatohepatitis in liver biopsies. Histological and clinical progression were assessed during follow-up. Patients with steatohepatitis had higher BMIs, liver stiffness, HbA1c and soluble (sCD163) and were more prone to have metabolic syndrome at baseline compared with simple steatosis patients. Of the 129 patients, 31 had a follow-up biopsy after a median of 287 days; simple steatosis progressed to steatohepatitis in 7 cases, while 2 regressed. Twenty patients had the same fibrosis stage according to the follow-up biopsy, seven progressed and four regressed. Only 14 patients progressed clinically (median follow-up time was 3.8 years). Clinical progression was associated with female sex, high creatinine, high sCD163 and disease severity in the diagnostic liver biopsy. Steatohepatitis was associated with metabolic and inflammatory parameters including fibroscan. Disease progression was seen in only 11% of cases and was mainly related to more severe histological disease at baseline.

New Insights in Cytokines in Childhood Obesity: Changes in TWEAK and CD163 After a 2-Year Intervention Program in Prepubertal Children With Obesity

OBJECTIVE

Obesity is characterized by a low-grade inflammatory state in adipose tissue. Tumor Necrosis Factor Weak Inducer of Apoptosis (TWEAK) and Cluster of Differentiation 163 (CD163) are cytokines potentially involved in the pathogenesis of obesity. Little is known about them in children. The aim of this study was to observe serum levels of TWEAK and CD163 in prepubertal children with obesity compared to lean, and to evaluate its changes after a 2-year intervention program in children with obesity.

METHODS

Case-control study with a prospective follow-up of cases for 2 years in a referral pediatric endocrine outpatient centre. Seventy-three prepubertal children with obesity, and forty-seven age- and gender-matched lean controls were studied. Sixty-two cases finished the program. Anthropometric parameters, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), lipid profile, and concentrations of TWEAK and CD163 were determined. Children with obesity were re-evaluated after a 2-year intervention program consisting of diet and exercise. Weight loss was considered if z-score Body Mass Index (BMI) decreased at least 0.5 Standard Deviations (SD).

RESULTS

We observed higher CD163 levels in children with obesity compared to controls. No significant differences were observed in TWEAK and CD163/TWEAK ratio at baseline. After the 2-year intervention program, TWEAK levels were higher and CD163/TWEAK ratio was lower in children with weight loss than those without weight loss. CD163 decreased in both groups.

CONCLUSION

TWEAK and CD163 seem to have a role in the pathogenesis of obesity in prepubertal children.

Can a Multicomponent-Overnight Camp Increase Physical Activity Among Danish Children? A Retrospective Cross-Sectional Study

BACKGROUND

In Denmark, most children are not sufficiently physically active and only a few interventions have been found to increase long-term physical activity among overweight and obese children. The aim of our study was to investigate if children are physically active in correspondence to Danish recommendations after attending a multicomponent-overnight camp.

METHODS

A questionnaire was developed to estimate children's physical activity level and behavior and investigate how transport, economy, availability, time, motivation, and knowledge about physical activity affect children's physical activity level and behavior.

RESULTS

In this study, 60.9% of the children did vigorous physical activity (VPA) minimum 30 minutes 3 times per week up to 3 years after camp. Most children were physically active at a sports club (44.3%) and only 5.7% of the children did not participate in physical activity. Parental physical activity and child motivation toward physical activity were significantly (P < .05) associated with children doing VPA.

CONCLUSION

Our findings suggest that 60.9% of children who attended camp engage in VPA after camp, which compared with a recent Danish study, is more frequent than children who did not attend camp. Further investigations are needed to determine the long-term health effects in children attending interventions such as multicomponent-overnight camps.

Circulating Macrophage Activation Markers Predict Transplant-Free Survival in Patients With Primary Sclerosing Cholangitis

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a progressive liver disease characterized by bile duct inflammation and fibrosis. The role of macrophages in PSC development and progression is less studied. Macrophage activation markers soluble (s)CD163 and mannose receptor (sMR) are associated with disease severity and outcome in other liver diseases, but not previously investigated in PSC. We evaluated sCD163 and sMR regarding disease severity and prognosis in patients with PSC.

METHODS

We investigated 2 independent PSC cohorts from Oslo (n = 138) and Helsinki (n = 159) and analyzed blood sCD163 and sMR levels. The Mayo score, Enhanced Liver Fibrosis Test, and Amsterdam-Oxford model were assessed for comparison.

RESULTS

Median (interquartile range) sCD163 was 3.32 (2.27-5.60) and 1.96 (1.47-2.70) mg/L in the Oslo and Helsinki cohorts, respectively, reflecting differences in disease severity between cohorts. Median sMR was similar in both cohorts, 0.28 (0.22-0.44) and 0.28 mg/L (0.20-0.36), respectively. In both cohorts, sCD163 and sMR levels raised with increasing disease severity (liver enzymes, Mayo score, and enhanced liver fibrosis test). Patients with high baseline levels of sCD163 had shorter transplant-free survival than patients with low baseline levels. Furthermore, sCD163 was associated with transplant-free survival in univariate cox-regression analyses. Both sCD163 and sMR performed better in the Oslo cohort of more severely diseased patients than those in the Helsinki cohort of more mildly diseased patients.

DISCUSSION

Macrophage activation markers are elevated according to disease severity suggesting an important role of macrophages in PSC. Furthermore, sCD163 was identified as a prognostic marker and predictor of transplant-free survival in PSC (see Visual Abstract, Supplementary Digital Content 4, http://links.lww.com/CTG/A516).

Controversies and Opportunities in the Use of Inflammatory Markers for Diagnosis or Risk Prediction in Fatty Liver Disease

In the Western society, non-alcoholic fatty liver disease (NAFLD), characterized by the excessive accumulation of fat in the liver, represents the most common cause of chronic liver disease. If left untreated, approximately 15%-20% of patients with NAFLD will progress to non-alcoholic steatohepatitis (NASH), in which lobular inflammation, hepatocyte ballooning and fibrogenesis further contribute to a distorted liver architecture and function. NASH initiation has significant effects on liver-related mortality, as even the presence of early stage fibrosis increases the chances of adverse patient outcome. Therefore, adequate diagnostic tools for NASH are needed, to ensure that relevant therapeutic actions can be taken as soon as necessary. To date, the diagnostic gold standard remains the invasive liver biopsy, which is associated with several drawbacks such as high financial costs, procedural risks, and inter/intra-observer variability in histology analysis. As liver inflammation is a major hallmark of disease progression, inflammation-related circulating markers may represent an interesting source of non-invasive biomarkers for NAFLD/NASH. Examples for such markers include cytokines, chemokines or shed receptors from immune cells, circulating exosomes related to inflammation, and changing proportions of peripheral blood mononuclear cell (PBMC) subtypes. This review aims at documenting and critically discussing the utility of such novel inflammatory markers for NAFLD/NASH-diagnosis, patient stratification and risk prediction.

Macrophage Activation Markers, Soluble CD163 and Mannose Receptor, in Liver Fibrosis

Macrophages are essential components of the human host immune system, which upon activation facilitates a broad pallet of immunomodulatory events including release of pro- or anti-inflammatory cytokines and chemokines, restoration of immune homeostasis and/or wound healing. Moreover, some macrophage phenotypes are crucially involved in fibrogenesis through stimulation of myofibroblasts, while others promote fibrolysis. During the last decades, the role of resident liver macrophages viz. Kupffer cells and recruited monocytes/macrophages in acute and chronic liver diseases has gained interest and been extensively investigated. Specifically, the scavenger receptors CD163 and mannose receptor (CD206), expressed by macrophages, are of utmost interest since activation by various stimuli induce their shedding to the circulation. Thus, quantifying concentrations of these soluble biomarkers may be of promising clinical relevance in estimating the severity of inflammation and fibrosis and to predict outcomes such as survival. Here, we review the existing literature on soluble CD163 and soluble mannose receptor in liver diseases with a particular focus on their relationship to hepatic fibrosis in metabolic associated fatty liver disease, as well as in chronic hepatitis B and C.

Performance of serum CD163 as a marker of fibrosis in patients with NAFLD

BACKGROUND AND AIMS

CD163, a surface hemoglobin-haptoglobin scavenger receptor, is expressed on macrophages and monocytes and up-regulated during macrophage activation. This study aimed to evaluate CD163 in nonalcoholic steatohepatitis patients as a diagnostic and prognostic marker in such patients.

METHODS

Serum samples were collected from 41 NAFLD patients and 14 healthy controls. All cases were subjected to clinical assessment, abdominal ultrasound examination, laboratory assessment including liver function and enzymes, kidney function, and lipid profile. Fib-4 and NAFLD fibrosis score were calculated for all patients. Also, serum levels of CD163 were detected by ELISA technique.

RESULTS

The present study showed that BMI, NAFLD fibrosis score (NFS), uric acid, cholesterol, and triglyceride levels were significantly elevated in the NAFLD cases compared with healthy controls (P < 0.05). The serum level of sCD163 was considerably higher in NAFLD cases (9.97 ± 9.97 ng/ml) vs. healthy controls (1.87 ± 0.83 ng/ml) (p < 0.001). Circulating level of sCD163 was significantly higher in the obese-diabetic subjects and diabetic non-obese patients as compared with the lean healthy subjects (11.15 ± 7.69 ng/ml) and 11.46 ± 13.83 ng/ml vs. 1.87 ± 0.83 ng/ml, P < 0.05; respectively. The sensitivity and specificity of this marker was 85.4%, and 92.9 for distinguishing patients with NAFLD in obese and/or diabetic subjects from healthy controls.

CONCLUSION

serum level of CD163 can be used as a diagnostic marker for individuals with NAFLD. However, it didn't correlate with NAFLD fibrosis score of those patients and thus couldn't predict the severity of disease.

Current perspectives on the pathophysiology of metabolic associated fatty liver disease: are macrophages a viable target for therapy?

INTRODUCTION

Metabolic associated fatty liver disease (MAFLD) is a new nomenclature for fatty liver replacing nonalcoholic fatty liver disease (NAFLD). MAFLD has emerged as the leading cause of liver-related morbidity and mortality with increasing incidence due to its close association with the global epidemic of obesity and type 2 diabetes mellitus. Macrophages play a key role in MAFLD development and progression of steatohepatitis and fibrosis. Therefore, targeting macrophages may be a new therapeutic approach for MAFLD and MAFLD with steatohepatitis.

AREAS COVERED

We provide a comprehensive review of the significant role of macrophages in MAFLD. Further, we evaluate the current status of lifestyle interventions and pharmacological treatments with a focus on effects mediated through direct or indirect targeting of macrophages.

EXPERT OPINION

Targeting macrophages holds promise as a treatment option for the management of MAFLD and steatohepatitis. Improved stratification of patients according to MAFLD phenotype would contribute to more adequate design enhancing the yield of clinical trials ultimately leading to personalized medicine for patients with MAFLD. Furthermore, reflecting the multifactorial pathogenesis of MAFLD, combination therapies based on the various pathophysiological driver events including as pertinent to this review, macrophage recruitment, polarization and action, present an intriguing target for future investigation.

Intestinal Barrier Function in Health and Disease-Any role of SARS-CoV-2?

Alterations in the structure and function of the intestinal barrier play a role in the pathogenesis of a multitude of diseases. During the recent and ongoing coronavirus disease (COVID-19) pandemic, it has become clear that the gastrointestinal system and the gut barrier may be affected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, and disruption of barrier functions or intestinal microbial dysbiosis may have an impact on the progression and severity of this new disease. In this review, we aim to provide an overview of current evidence on the involvement of gut alterations in human disease including COVID-19, with a prospective outlook on supportive therapeutic strategies that may be investigated to rescue intestinal barrier functions and possibly facilitate clinical improvement in these patients.

Serum LPS and CD163 Biomarkers Confirming the Role of Gut Dysbiosis in Overweight Patients with NASH

BACKGROUND

Gut-microbiota alterations and bacterial translocation might attribute to hepatic inflammation. Lipopolysaccharide stimulates toll-like receptor 4 leading to the activation of Kupffer cells which express the surface receptor, CD 163.

OBJECTIVE

To assess the levels of CD 163 and LPS in overweight and obese patients with different degrees of NAFLD as confirmed by liver biopsy (NAS score).

METHODS

This is an observational case-control study. Sixty overweight and obese patients with NAFLD and 40 healthy controls were enrolled in the study. Liver biopsy was obtained from all participants with NAFLD. LPS and CD 163 levels were assessed using ELISA.

RESULTS

The mean LPS and CD163 levels were significantly higher in patients with NAFLD when compared with healthy controls (p-value <0.001, p-value <0.001, respectively). LPS and CD163 levels were the lowest in Non-NASH (13.17 ± 3.34, 5.61 ± 2.35 ng/mL, respectively) and the highest in NASH (58.61 3± 3.81, 18.11 ± 6.84, respectively) (p-value <0.001, p-value <0.001, respectively). Statistically significant correlation was found between the levels of LPS and CD163 and NAS score (p-value <0.001, p-value < 0.001, respectively), steatosis grade (p-value <0.001, p-value <0.001, respectively), degree of inflammation (p-value 0.017, p-value <0.001, respectively) and ballooning (r= 0.663, p-value <0.001, r= 0.558, p-value <0.001, respectively). In ROC analysis, both sCD163 and LPS had high sensitivity and specificity in diagnosing NAFLD. CD163 and LPS had the high sensitivity and accuracy in discriminating NASH from Non-NASH (p-value <0.0001 in both). Moreover, the mean serum levels of LPS and sCD163 correlated positively and significantly with the BMI (r=0.329, p value<0.01; r=0.477. p value <0.001, respectively).

CONCLUSION

sCD163 and LPS can be used as non-invasive tools for diagnosis and grading of NAFLD severity in overweight and obese patients, thus confirming the role of dysbiosis in fat deposition and inflammation and suggesting the potential benefits of gut-microbiota-targeted therapies in restoring the gut homeostasis.

What Change in Body Mass Index Is Required to Improve Cardiovascular Outcomes in Childhood and Adolescent Obesity through Lifestyle Interventions: A Meta-Regression

Background: Using meta-regression, this article aims at establishing the minimum change in BMI-standard deviation score (SDS) needed to improve lipid profiles and blood pressure in children and adolescents with obesity, to aid future trials and guidelines. Methods: Studies with participants involved in lifestyle interventions, aged 4-19 years, with a diagnosis of obesity according to defined BMI thresholds, were considered for inclusion in a large systematic review. Interventions had to report pre- and post-intervention (or mean change in) BMI-SDS, plus either systolic blood pressure (SBP), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and/or triglycerides (TGs). Random-effects meta-regression quantified the relationship between mean change in BMI-SDS and mean change in cardiovascular outcomes. Results: Seventy-one papers reported various cardiovascular measurements and mean change in BMI-SDS. Fifty-four, 59, 46, and 54 studies were analyzed, reporting a change in SBP, HDL, LDL, and TG, respectively. Reduction in mean BMI-SDS was significantly related to improvements in SBP, LDL, TG, and HDL (p < 0.05); BMI-SDS reductions of 1, 1.2, and 0.7 ensured a mean reduction of SBP, LDL, and TG, respectively, although an equivalent value for HDL improvement was indeterminate. Conclusion: Reductions in mean BMI-SDS of >1, >1.2, or >0.7 are likely to reduce SBP, LDL, and TG, respectively. Further studies are needed to clarify the optimal duration, intensity, and setting for interventions. Consistency is required regarding derived BMI values to facilitate future systematic reviews and meta-analyses.

Iron Metabolism in Obesity and Metabolic Syndrome

Obesity is an excessive adipose tissue accumulation that may have detrimental effects on health. Particularly, childhood obesity has become one of the main public health problems in the 21st century, since its prevalence has widely increased in recent years. Childhood obesity is intimately related to the development of several comorbidities such as nonalcoholic fatty liver disease, dyslipidemia, type 2 diabetes mellitus, non-congenital cardiovascular disease, chronic inflammation and anemia, among others. Within this tangled interplay between these comorbidities and associated pathological conditions, obesity has been closely linked to important perturbations in iron metabolism. Iron is the second most abundant metal on Earth, but its bioavailability is hampered by its ability to form highly insoluble oxides, with iron deficiency being the most common nutritional disorder. Although every living organism requires iron, it may also cause toxic oxygen damage by generating oxygen free radicals through the Fenton reaction. Thus, iron homeostasis and metabolism must be tightly regulated in humans at every level (i.e., absorption, storage, transport, recycling). Dysregulation of any step involved in iron metabolism may lead to iron deficiencies and, eventually, to the anemic state related to obesity. In this review article, we summarize the existent evidence on the role of the most recently described components of iron metabolism and their alterations in obesity.

Soluble CD163 and mannose receptor as markers of liver disease severity and prognosis in patients with primary biliary cholangitis

INTRODUCTION

In primary biliary cholangitis (PBC), macrophages are involved in liver inflammation and fibrosis. The macrophage activation markers, soluble (s)CD163 and mannose receptor (sMR) are associated with liver disease severity and prognosis in other chronic liver diseases. We aimed to investigate sCD163 and sMR in patients with PBC.

METHODS

We investigated PBC patients from the Italian PBC Study Group cohort and measured macrophage activation markers in serum at study enrolment. Patients were followed from enrolment until they experienced an event or were censored at their last visit. Events were defined as follows: (a) death from a liver-related cause; or (b) liver transplantation (LT) for PBC. We used Cox regression to investigate the association between sCD163 and sMR and long-term prognosis.

RESULTS

In total, 202 PBC patients were included. Median age was 62 years (interquartile range (IQR), 53-71) at enrolment and 93% were women. Median sCD163 was 3.43 mg/L (IQR 2.48-5.35) and median sMR was 0.35 mg/L (IQR 0.28-0.45). There was an increase in sCD163 and sMR with increasing alkaline phosphatase. Two hundred and one patients were followed for a median of 8.6 years, and sCD163 and sMR predicted long-term risk of liver-related death or LT in univariate analyses, while sCD163 was also associated with outcome after confounder adjusting (adjusted HR = 1.14, 95% CI 1.00-1.30). Finally, we showed an increase in the prediction accuracy of poor outcome by adding sCD163 to the UK-PBC risk score.

CONCLUSION

The macrophage activation markers sCD163 and sMR represent a non-invasive measure of PBC disease severity that provides useful long-term prognostic information.

Macrophage Activation Markers, CD163 and CD206, in Acute-on-Chronic Liver Failure

Macrophages facilitate essential homeostatic functions e.g., endocytosis, phagocytosis, and signaling during inflammation, and express a variety of scavenger receptors including CD163 and CD206, which are upregulated in response to inflammation. In healthy individuals, soluble forms of CD163 and CD206 are constitutively shed from macrophages, however, during inflammation pathogen- and damage-associated stimuli induce this shedding. Activation of resident liver macrophages viz. Kupffer cells is part of the inflammatory cascade occurring in acute and chronic liver diseases. We here review the existing literature on sCD163 and sCD206 function and shedding, and potential as biomarkers in acute and chronic liver diseases with a particular focus on Acute-on-Chronic Liver Failure (ACLF). In multiple studies sCD163 and sCD206 are elevated in relation to liver disease severity and established as reliable predictors of morbidity and mortality. However, differences in expression- and shedding-stimuli for CD163 and CD206 may explain dissimilarities in prognostic utility in patients with acute decompensation of cirrhosis and ACLF.

Change in obesity-related metabolic abnormalities associated with body mass index improvement through life-style intervention: A meta-regression

The reduction in body mass index standard deviation score (BMI-SDS) associated with improvement in biomarkers relating to metabolic health in obese children is unknown. We aimed to establish the change in BMI-SDS associated with improved inflammation, liver function, and insulin resistance to inform clinical guidelines for pediatric weight management interventions and to assess the efficacy of future trials. A large-scale systematic review was conducted to identify relevant studies. Studies of children with a diagnosis of obesity according to defined BMI thresholds, participating in lifestyle interventions to reduce obesity, were included. Studies must have reported baseline (pre-) and postintervention (or change of) BMI-SDS and either fasting glucose, homeostatic model of insulin resistance (HOMA-IR), alanine aminotransferase (ALT), C-reactive protein (CRP), or interleukin-6 (IL-6). A series of meta-regressions were conducted to establish links between BMI-SDS change scores and change in metabolic markers of health. Sixty-eight articles were identified. From the meta-regression analyses, across all study subsets, greater mean falls in all four parameters, (HOMA-IR, Glucose, ALT, and CRP) were observed with greater mean loss of BMI-SDS, but the trends were only statistically significant for HOMA-IR and CRP (P = .003; P = .021). However, we could not find minimum changes in BMI-SDS that would ensure a fall in these outcomes. At this time, we are unable to recommend a definitive value of BMI-SDS reduction needed to improve the markers of metabolic health. Future trials should aim to report additional indices of derived BMI values, which may better reflect changes in actual adiposity.

Crosstalk between adipose tissue insulin resistance and liver macrophages in non-alcoholic fatty liver disease

BACKGROUND & AIMS

The pathogenesis of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) is likely due to the interaction between a deranged metabolic milieu and local mediators of hepatic inflammation and fibrosis. We undertook this study to elucidate the interplay between macrophage activation, insulin resistance (IR) in target organs/tissues and hepatic damage.

METHODS

In 40 non-diabetic patients with biopsy-proven NAFLD we assessed: i) endogenous glucose production (EGP), glucose clearance and indexes of IR in the adipose tissue (Adipo-IR and Lipo-IR) and in the liver (Hep-IR) by tracer infusion ([6,6-2H2]glucose and [2H5]glycerol); ii) macrophage activity (by soluble sCD163) and iii) hepatic expression of CD163 (hCD163).

RESULTS

We found that sCD163 levels paralleled both the plasma free fatty acid (FFA) levels and lipolysis from adipose tissue. Consistently, sCD163 significantly correlated with adipose tissue IR (Adipo-IR: r = 0.32, p = 0.042; Lipo-IR: r = 0.39, p = 0.012). At multiple regression analysis, sCD163 levels were associated with FFA levels (r_p = 0.35, p = 0.026). In vitro exposure of human monocyte-derived macrophages to palmitate enhanced sCD163 secretion. Conversely, sCD163 did not correlate with EGP or with Hep-IR. In the liver, hCD163 positively correlated with sCD163 (r = 0.58, p = 0.007) and the degree of steatosis (r = 0.34, p = 0.048), but not with EGP or Hep-IR (r = -0.27 and r = 0.11, respectively, p >0.10, both).

CONCLUSIONS

Our findings suggest a link between deranged metabolism in the adipose tissue and activation of hepatic macrophages in patients with NAFLD, possibly in response to FFA overflow and independent of obesity and diabetes. Conversely, our findings do not support a link between activated hepatic macrophages and glucose metabolism (EGP or Hep-IR). The relationship between adipose tissue IR and hepatic macrophages should be considered to define therapeutic targets for NAFLD.

LAY SUMMARY

The pathogenesis of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) is likely due to the interaction between a deranged metabolic milieu and local mediators of hepatic inflammation and fibrosis in the insulin resistant state. This study provides in vivo support for a possible link between deranged metabolism in the adipose tissue and activation of hepatic macrophages in patients with NAFLD, most likely in response to free fatty acid overflow and independent of obesity and diabetes.

What change in body mass index is associated with improvement in percentage body fat in childhood obesity? A meta-regression

OBJECTIVE

Using meta-regression this paper sets out the minimum change in body mass index-SD score (BMI-SDS) required to improve adiposity as percentage body fat for children and adolescents with obesity.

DESIGN

Meta-regression.

SETTING

Studies were identified as part of a large-scale systematic review of the following electronic databases: AMED, Embase, MEDLINE via OVID, Web of Science and CENTRAL via Cochrane library.

PARTICIPANTS

Individuals aged 4-19 years with a diagnosis of obesity according to defined BMI thresholds.

INTERVENTIONS

Studies of lifestyle treatment interventions that included dietary, physical activity and/or behavioural components with the objective of reducing obesity were included. Interventions of <2 weeks duration and those that involved surgical and/or pharmacological components (eg, bariatric surgery, drug therapy) were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES

To be included in the review, studies had to report baseline and post-intervention BMI-SDS or change measurements (primary outcome measures) plus one or more of the following markers of metabolic health (secondary outcome measures): adiposity measures other than BMI; blood pressure; glucose; inflammation; insulin sensitivity/resistance; lipid profile; liver function. This paper focuses on adiposity measures only. Further papers in this series will report on other outcome measures.

RESULTS

This paper explores the potential impact of BMI-SDS reduction in terms of change in percentage body fat. Thirty-nine studies reporting change in mean percentage body fat were analysed. Meta-regression demonstrated that reduction of at least 0.6 in mean BMI-SDS ensured a mean reduction of percentage body fat mass, in the sense that the associated 95% prediction interval for change in mean percentage body fat was wholly negative.

CONCLUSIONS

Interventions demonstrating reductions of 0.6 BMI-SDS might be termed successful in reducing adiposity, a key purpose of weight management interventions.

TRIAL REGISTRATION NUMBER

CRD42016025317.

Fatty Liver Among Adolescent Offspring of Women With Type 1 Diabetes (the EPICOM Study)

OBJECTIVE

Intrauterine exposure to maternal type 1 diabetes is associated with a less favorable metabolic profile later in life. Nonalcoholic fatty liver disease is the hepatic manifestation of a cluster of metabolic abnormalities linked to insulin resistance. This study aimed to evaluate the effect of maternal pregestational type 1 diabetes on the presence of fatty liver in offspring and the association between maternal BMI, glycemic control during pregnancy, offspring metabolic risk factors, and offspring level of soluble CD163 (sCD163) (a marker of macrophage activation) and risk of fatty liver.

RESEARCH DESIGN AND METHODS

This study was a prospective nationwide follow-up study of offspring (n = 278) of mothers with pregestational type 1 diabetes between 1993 and 1999 and matched control subjects (n = 303). Mean age at the time of follow-up was 16.7 years (range 13.0-20.4 years). We used the fatty liver index (FLI) and waist-to-height ratio (WHtR) to evaluate the presence of fatty liver among the offspring. An FLI ≥60 or WHtR >0.469 were used as cutoff points for fatty liver.

RESULTS

More type 1 diabetes-exposed offspring had high FLI and WHtR indices compared with unexposed control subjects. We found significant associations between increasing maternal prepregnancy BMI, being born large for gestational age, offspring level of sCD163, as well as offspring metabolic risk factors (decreasing adiponectin and HDL cholesterol and increasing leptin, HOMA of insulin resistance, and HOMA of insulin secretion) and degree of fatty liver.

CONCLUSIONS

Intrauterine exposure to maternal type 1 diabetes and higher maternal prepregnancy BMI may predispose to fatty liver in the offspring. Offspring metabolic risk factors, including sCD163 levels, are associated with indices of fatty liver.

The role of macrophages in nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) and its inflammatory and often progressive subtype nonalcoholic steatohepatitis (NASH) are becoming the leading cause of liver-related morbidity and mortality worldwide, and a primary indication for liver transplantation. The pathophysiology of NASH is multifactorial and not yet completely understood; however, innate immunity is a major contributing factor in which liver-resident macrophages (Kupffer cells) and recruited macrophages play a central part in disease progression. In this Review, we assess the evidence for macrophage involvement in the development of steatosis, inflammation and fibrosis in NASH. In this process, not only the polarization of liver macrophages towards a pro-inflammatory phenotype is important, but adipose tissue macrophages, especially in the visceral compartment, also contribute to disease severity and insulin resistance. Macrophage activation is mediated by factors such as endotoxins and translocated bacteria owing to increased intestinal permeability, factors released from damaged or lipoapoptotic hepatocytes, as well as alterations in gut microbiota and defined nutritional components, including certain free fatty acids, cholesterol and their metabolites. Reflecting the important role of macrophages in NASH, we also review studies investigating drugs that target macrophage recruitment to the liver, macrophage polarization and their inflammatory effects as potential treatment options for patients with NASH.

Macrophages in the Aging Liver and Age-Related Liver Disease

The number of individuals aged 65 or older is projected to increase globally from 524 million in 2010 to nearly 1. 5 billion in 2050. Aged individuals are particularly at risk for developing chronic illness, while being less able to regenerate healthy tissue and tolerate whole organ transplantation procedures. In the liver, these age-related diseases include non-alcoholic fatty liver disease, alcoholic liver disease, hepatitis, fibrosis, and cirrhosis. Hepatic macrophages, a population comprised of both Kupffer cells and infiltrating monocyte derived macrophages, are implicated in several chronic liver diseases and also play important roles in the homeostatic functions of the liver. The effects of aging on hepatic macrophage population dynamics, polarization, and function are not well understood. Studies performed on macrophages derived from other aged sources, such as the bone marrow, peritoneal cavity, lungs, and brain, demonstrate general reductions in autophagy and phagocytosis, dysfunction in cytokine signaling, and altered morphology and distribution, likely mediated by epigenetic changes and mitochondrial defects, that may be applicable to hepatic macrophages. This review highlights recent findings in macrophage developmental biology and function, particularly in the liver, and discusses the role of macrophages in various age-related liver diseases. A better understanding of the biology of aging that influences hepatic macrophages and thus the progression of chronic liver disease will be crucial in order to develop new interventions and treatments for liver disease in aging populations.

Macrophage Markers Are Poorly Associated With Liver Histology in Children With Nonalcoholic Fatty Liver Disease

OBJECTIVES

We have previously demonstrated associations between the macrophage activation marker soluble (s)CD163 and histology of nonalcoholic fatty liver disease (NAFLD) in adults, and elevated sCD163 levels in children with obesity with NAFLD. Macrophage activation has, however, not been investigated in children with biopsy-proven NAFLD, which was the objective of the present study.

METHODS

We used in-house enzyme-linked immunosorbent assays to measure sCD163 and the novel macrophage marker soluble mannose receptor (sMR) in a cross-sectional (n = 155) pediatric NAFLD cohort, and a cohort of NAFLD children (n = 36) undergoing a randomized trial by the probiotic VSL#3. We included 56 healthy nonobese children for comparison.

RESULTS

Levels of sCD163 and sMR were higher in both of the NAFLD cohorts compared with controls (P < 0.001). In the cross-sectional cohort, sCD163 only showed trends toward association with ballooning (rho = 0.14, P = 0.08) and portal inflammation (rho = 0.17, P = 0.08). sMR showed similar associations with liver histology. In the VSL#3 cohort, sCD163 correlated inversely with steatosis (rho = -0.35, P = 0.04), and lobular (rho = -0.57, P < 0.001) and portal inflammation (rho = -0.38, P = 0.02); sMR was not associated with any histological scores. Neither sCD163 nor sMR changed significantly during intervention, and without association with NAFLD resolution.

CONCLUSIONS

The macrophage activation markers sCD163 and sMR showed poor associations with liver histology in 2 different cohorts of children with biopsy-proven NAFLD, and none of the markers decreased during successful intervention. These results are in contrast with studies of adult NAFLD and may suggest a possibility of different roles for macrophages in the pathogenesis of adult and pediatric NAFLD.

Effect of Endoplasmic Reticular Stress on Free Hemoglobin Metabolism and Liver Injury

Elevated soluble (s) CD163 and free hemoglobin (Hb) levels predict fatty liver progression; however, the molecular mechanisms underlying Hb metabolism and liver injury remain undefined. We investigated the effects of endoplasmic reticular (ER) stress on red blood cell (RBC) rheology and free Hb recycling pathways. ER stress was induced in Sprague-Dawley rats by an intraperitoneal injection of tunicamycin (TM) (50, 100, and 200 μg/100 g body weight (BW)) or an intravenous injection of Hb (5 mg/100 g BW). A TM injection increased sCD163 levels, attenuated free Hb uptake, and maintained RBC aggregability. An Hb injection increased serum LVV-hemorphin-7 and total bilirubin levels, but this effect was suppressed by TM. A Western blot analysis showed that ER stress suppressed Hb degradation in the liver through downregulation of globin degradation proteins cathepsin D and glyoxalase-1, as well as heme degradation protein heme oxyganase-1 and keap-1 expression. An ER stress activator also increased the translocation of nuclear factor (NF)-κB (p65) and nuclear factor-erythroid 2-related factor 2 (Nrf2) to nuclei. In conclusion, ER stress triggers ineffective Hb metabolism via altering globin and heme iron degradation pathways. Inability to recycle and metabolize free Hb may underlie the association between iron dysfunction and liver injury.

Emerging therapeutic biomarkers of autoimmune hepatitis and their impact on current and future management

Autoimmune hepatitis lacks a quantifiable biomarker that is close to its pathogenic mechanisms and that accurately reflects inflammatory activity, correlates with treatment response, and ensures inactive disease before treatment withdrawal. Areas covered: Micro-ribonucleic acids, programmed death-1 protein and its ligands, macrophage migration inhibitory factor, soluble CD163, B cell activating factor, and metabolite patterns in blood were considered the leading candidates as therapeutic biomarkers after search of PubMed from August 1981 to August 2017 using the search words 'biomarkers of autoimmune hepatitis'. Expert commentary: Each of the candidate biomarkers is close to the putative pathogenic mechanisms of autoimmune hepatitis, and each has attributes that support its potential role as a surrogate marker of inflammatory activity that can be monitored during treatment. Future studies must demonstrate the superiority of each biomarker to conventional indices of inflammatory activity and validate their correlation with treatment response and outcome. A reliable therapeutic biomarker would facilitate the individualization of current management algorithms, ensure that pathogenic mechanisms were disrupted or eliminated prior to treatment withdrawal, and reduce the frequency of relapse or unnecessary protracted therapy. The biomarker might also prove to be a target of next-generation therapies.

An assessment of racial differences in the upper limits of normal ALT levels in children and the effect of obesity on elevated values

OBJECTIVES

Childhood obesity is a risk factor for non-alcoholic fatty liver disease and poses important public health issues for children. Racial differences in alanine aminotransferase (ALT) levels among children have not been described. This study aimed to identify racial differences in upper limit normal (ULN) ALT levels and evaluate the effect of obesity on elevated levels in children without other metabolic risk factors.

METHODS

National Health and Nutrition Examination Surveys and clinical data from the Loyola University Health System were used to determine ULN ALT by race and gender. Quantile regression was used to evaluate the impact of obesity on elevated ALT and to identify potential risk factors for ALT above the ULN.

RESULTS

Upper limit normal (ULN) ALT was approximately 28.0 and 21.0-24.0 U/L for boys and girls, respectively. No significant difference in ULN ALT across race was observed. Obesity was significantly associated with elevated ALT; obese children with elevated ALT had values 10 U/L higher than normal-weight children.

CONCLUSIONS

Racial differences in ALT levels among adults are not evident in children. Obesity, in the absence of metabolic risk factors and other causes of liver disease, is associated with elevated ALT, providing evidence against the concept of healthy obesity in children.

An Alternatively Activated Macrophage Marker CD163 in Severely Obese Patients: the Influence of Very Low-Calorie Diet and Bariatric Surgery

CD163 is a marker of macrophages with anti-inflammatory properties and its soluble form (sCD163) is considered a prognostic predictor of several diseases including type 2 diabetes mellitus (T2DM). We explored sCD163 levels at baseline and after very low-calorie diet (VLCD) or bariatric surgery in 32 patients with obesity (20 undergoing VLCD and 12 bariatric surgery), 32 obese patients with T2DM (22 undergoing VLCD and 10 bariatric surgery), and 19 control subjects. We also assessed the changes of CD163 positive cells of monocyte-macrophage lineage in peripheral blood and subcutaneous adipose tissue (SAT) in subset of patients. Plasma sCD163 levels were increased in obese and T2DM subjects relative to control subjects (467.2±40.2 and 513.8±37.0 vs. 334.4±24.8 ng/ml, p=0.001) and decreased after both interventions. Obesity decreased percentage of CD163+CD14+ monocytes in peripheral blood compared to controls (78.9±1.48 vs. 86.2±1.31 %, p=0.003) and bariatric surgery decreased CD163+CD14+HLA-DR+ macrophages in SAT (19.4±2.32 vs. 11.3±0.90 %, p=0.004). Our data suggest that increased basal sCD163 levels are related to obesity and its metabolic complications. On the contrary, sCD163 or CD163 positive cell changes do not precisely reflect metabolic improvements after weight loss.

Insulin Resistance and Markers of Inflammation in HIV-infected Ugandan Children in the CHAPAS-3 Trial

BACKGROUND

Few studies have investigated metabolic complications in HIV-infected African children and their relation with inflammation.

METHODS

We compared baseline and changes in insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR)] and in markers of inflammation over 48 weeks, in a subset of antiretroviral therapy (ART)-naive Ugandan children from the Children with HIV in Africa-Pharmacokinetics and Adherence/Acceptability of Simple Antiretroviral Regimens trial randomized to zidovudine-, stavudine- or abacavir (ABC)-based regimen. Nonparametric methods were used to explore between-group and within-group differences, and multivariable analysis to assess associations of HOMA-IR.

RESULTS

One-hundred eighteen children were enrolled, and median age (interquartile range) was 2.8 years (1.7-4.3). Baseline median HOMA-IR (interquartile range) was 0.49 (0.38-1.07) and similar between the arms. At week 48, median relative changes in HOMA-IR were 14% (-29% to 97%) in the zidovudine arm, -1% (-30% to 69%) in the stavudine arm and 6% (-34% to 124%) in the ABC arm (P ≤ 0.03 for all the arms compared with baseline, but P = 0.90 for between-group differences). Several inflammation markers significantly decreased in all study arms; soluble CD14 increased on ABC and did not change in the other 2 arms. In multivariate analysis, only changes in soluble CD163 were positively associated with HOMA-IR changes.

CONCLUSIONS

In ART-naive Ugandan children, HOMA-IR changed significantly after 48 weeks of ART and correlated with monocyte activation.

Liver macrophages in tissue homeostasis and disease

Macrophages represent a key cellular component of the liver, and are essential for maintaining tissue homeostasis and ensuring rapid responses to hepatic injury. Our understanding of liver macrophages has been revolutionized by the delineation of heterogeneous subsets of these cells. Kupffer cells are a self-sustaining, liver-resident population of macrophages and can be distinguished from the monocyte-derived macrophages that rapidly accumulate in the injured liver. Specific environmental signals further determine the polarization and function of hepatic macrophages. These cells promote the restoration of tissue integrity following liver injury or infection, but they can also contribute to the progression of liver diseases, including hepatitis, fibrosis and cancer. In this Review, we highlight novel findings regarding the origin, classification and function of hepatic macrophages, and we discuss their divergent roles in the healthy and diseased liver.

The Role of Tissue Macrophage-Mediated Inflammation on NAFLD Pathogenesis and Its Clinical Implications

The obese phenotype is characterized by a state of chronic low-grade systemic inflammation that contributes to the development of comorbidities, including nonalcoholic fatty liver disease (NAFLD). In fact, NAFLD is often associated with adipocyte enlargement and consequent macrophage recruitment and inflammation. Macrophage polarization is often associated with the proinflammatory state in adipose tissue. In particular, an increase of M1 macrophages number or of M1/M2 ratio triggers the production and secretion of various proinflammatory signals (i.e., adipocytokines). Next, these inflammatory factors may reach the liver leading to local M1/M2 macrophage polarization and consequent onset of the histological damage characteristic of NAFLD. Thus, the role of macrophage polarization and inflammatory signals appears to be central for pathogenesis and progression of NAFLD, even if the heterogeneity of macrophages and molecular mechanisms that govern their phenotype switch remain incompletely understood. In this review, we discuss the role of adipose and liver tissue macrophage-mediated inflammation in experimental and human NAFLD. This focus is relevant because it may help researchers that approach clinical and experimental studies on this disease advancing the knowledge of mechanisms that could be targeted in order to revert NAFLD-related fibrosis.

The macrophage activation product sCD163 is associated with a less favourable metabolic profile in prepubertal children

OBJECTIVE

Macrophages are known to be involved in low-grade inflammatory processes such as obesity. soluble cluster of differentiation 163 (sCD163) is shed from the cell surface as specific macrophage activation marker. In prepubertal children, we studied if circulating sCD163 is associated with metabolic and cardiovascular risk markers.

METHODS

A population of 236 school-aged Caucasian children (111 girls and 125 boys) aged 8 ± 1 year [81 normal weight (body mass index [BMI]-SDS < 1); 74 overweight (1 ≤ BMI-standard deviation score [SDS] < 2) and 81 with obesity (BMI-SDS ≥ 2)] were studied. BMI, waist circumference, fat mass and visceral fat were measured. Fasting serum sCD163, homeostatic model assessment of insulin resistance, high sensitivity C-reactive protein, gamma-glutamyl transpeptidase and lipids were quantified.

RESULTS

Circulating sCD163 concentrations were higher in children with obesity (p < 0.0001). Associations were observed between circulating sCD163 and a less favourable metabolic profile as judged by higher waist circumference, fat mass, visceral fat, epicardial fat, homeostatic model assessment of insulin resistance, high sensitivity C-reactive protein, gamma-glutamyl transpeptidase and triglycerides (all between r = 0.173 and r = 0.363; p < 0.05 to p < 0.0001) and lower high-density lipoprotein-cholesterol (r = -0.285, p < 0.0001). In multiple regression analyses, circulating sCD163 was independently associated with HOMA-IR (β = 0.162, p = 0.016; model R²  = 0.179) and high density lipoprotein-cholesterol/triglycerides ratio (β = -0.167, p = 0.012; model R²  = 0.209).

CONCLUSIONS

Childhood obesity may increase the risk of developing metabolic diseases later in life through chronic macrophage activation having deleterious effects on metabolism.

Placebo-controlled, randomised clinical trial: high-dose resveratrol treatment for non-alcoholic fatty liver disease

OBJECTIVE

"The obesity epidemic" has led to an increase in obesity-related conditions including non-alcoholic fatty liver disease (NAFLD), for which effective treatments are in demand. The polyphenol resveratrol prevents the development of experimental NAFLD through modulation of cellular pathways involved in calorie restriction. We aimed to test the hypothesis that resveratrol alleviates NAFLD in a randomised, clinical trial.

MATERIALS AND METHODS

A total of 28 overweight patients with transaminasemia and histological NAFLD were randomised 1:1 to placebo or resveratrol 1.5 g daily for 6 months. Twenty-six participants completed the trial and underwent repeated clinical investigation, blood work, MR spectroscopy; and 19 participants agreed to a repeat liver biopsy.

RESULTS

Resveratrol treatment was generally not superior to placebo in improving plasma markers of liver injury (primary outcome: alanine transaminase, p = 0.51). Resveratrol-treated patients showed a 3.8% decrease in liver lipid content (p = 0.03), with no difference between the two treatment arms (p = 0.38) and no improvement of histological features. Resveratrol treatment was not associated with improvements in insulin sensitivity or markers of the metabolic syndrome, except for a transient decrease in systolic BP. Microarray analysis and qRT-PCR revealed no major changes in expression profile. Also, we report a serious adverse event in a patient who developed fever and bicytopenia.

CONCLUSIONS

In this placebo-controlled, high-dose and long-term study, resveratrol treatment had no consistent therapeutic effect in alleviating clinical or histological NAFLD, though there may be a small ameliorating effect on liver function tests and liver fat accumulation.

Single-centre experience of the macrophage activation marker soluble (s)CD163 - associations with disease activity and treatment response in patients with autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis (AIH) is characterised by liver inflammation with reversibility upon anti-inflammatory treatment. Soluble (s)CD163, a specific macrophage activation marker, is associated with inflammation in other liver diseases, but never investigated in AIH.

AIM

To investigate sCD163 in patients with acute AIH and in complete and incomplete responders to standard anti-inflammatory pharmacotherapy, and during follow-up in treatment naive patients.

METHODS

In a cross-sectional design, we studied 121 AIH patients (female/male 89/32, median age 49 years); of these, we prospectively studied 10 treatment naïve AIH patients during prednisolone treatment and tapering. Twenty patients had variant syndromes of AIH and primary biliary cholangitis or primary sclerosing cholangitis. sCD163 was compared with markers of disease activity, severity and treatment response.

RESULTS

In the patients with acute AIH (n = 21), sCD163 was sixfold increased compared with the normalised levels in patients (n = 32) with complete response to standard treatment [9.5 (3.3-28.8) vs. 1.6 (0.8-3.2) mg/L, P < 0.01)], while the patients (n = 27) with incomplete response had higher sCD163 [2.2 (1.3-7.9), P < 0.05] than the complete responders. sCD163 was positively associated with ALAT, IgG and bilirubin (rho: 0.45-0.59, P < 0.001, all), and negatively to external coagulation factors (rho:-0.34, P < 0.001). In the treatment naïve patients, sCD163 fell during high-dose prednisolone treatment and tapering. Immunohistochemical staining confirmed increased CD163 expression in liver biopsies from patients with acute AIH.

CONCLUSIONS

sCD163 was markedly elevated in AIH in the acute phase, normalised by successful treatment in complete responders, but remained higher in the incompletely responding cases. Our results demonstrate macrophage activation in AIH paralleling disease activity, severity and treatment response, suggesting a role for macrophage activation in AIH.

The macrophage activation marker sCD163 is associated with morphological disease stages in patients with non-alcoholic fatty liver disease

BACKGROUND & AIMS

Macrophage activation plays a key pathogenic role in experimental non-alcoholic fatty liver disease (NAFLD) and contributes to the progression of steatohepatitis (NASH) and fibrosis. We studied macrophage activation in human NAFLD by measuring soluble (s)CD163, a specific macrophage activation marker, hypothesizing that sCD163 would be associated with the patients' morphological disease grade. Furthermore, we investigated an association between sCD163 and the apoptosis marker cytokeratin-18 (CK-18) to explore a link between macrophage activation and apoptosis.

METHODS

sCD163 associations with biochemical and histological measures of NAFLD were investigated in two independent cohorts of 157 Australian and 174 Italian NAFLD patients, with liver biopsies graded for NAFLD severity, steatosis and fibrosis. sCD163 and CK-18 were measured by enzyme-linked immunosorbent assay.

RESULTS

In both cohorts sCD163 increased in parallel with the patients' morphological disease grading, being independently associated with the Kleiner fibrosis score (P < 0.001). A high sCD163 predicted advanced fibrosis {F ≥ 3; Australian cohort: area under receiver-operating characteristics curve 0.77 [95% confidence interval (CI): 0.76-0.87], Italian cohort: 0.80 (95% CI: 0.72-0.88)}. In both groups, sCD163 was independently associated with CK-18 (P < 0.001).

CONCLUSION

Soluble CD163 reflecting macrophage activation is associated with morphological features of NAFLD suggesting their involvement in the pathogenesis of NAFLD, NASH and particularly fibrosis. An independent association between sCD163 and cytokeratin-18 suggests that apoptosis may contribute to macrophage activation in NAFLD/NASH.

The Immune Landscape in Nonalcoholic Steatohepatitis

The liver lies at the intersection of multiple metabolic pathways and consequently plays a central role in lipid metabolism. Pathological disturbances in hepatic lipid metabolism are characteristic of chronic metabolic diseases, such as obesity-mediated insulin resistance, which can result in nonalcoholic fatty liver disease (NAFLD). Tissue damage induced in NAFLD activates and recruits liver-resident and non-resident immune cells, resulting in nonalcoholic steatohepatitis (NASH). Importantly, NASH is associated with an increased risk of significant clinical sequelae such as cirrhosis, cardiovascular diseases, and malignancies. In this review, we describe the immunopathogenesis of NASH by defining the known functions of immune cells in the progression and resolution of disease.

Reduced sCD36 following weight loss corresponds to improved insulin sensitivity, dyslipidemia and liver fat in obese children

BACKGROUND/OBJECTIVES

Childhood obesity is a major health problem with serious long-term metabolic consequences. CD36 is important for the development of obesity-related complications among adults. We aimed to investigate circulating sCD36 during weight loss in childhood obesity and its associations with insulin resistance, dyslipidemia, hepatic fat accumulation and low-grade inflammation.

SUBJECTS/METHODS

The impact of a 10-week weight loss camp for obese children (N=113) on plasma sCD36 and further after a 12-month follow-up (N=68) was investigated. Clinical and biochemical data were collected, and sCD36 was measured by an in-house assay. Liver fat was estimated by ultrasonography and insulin resistance by the homeostasis model assessment (HOMA-IR).

RESULTS

Along with marked weight loss, sCD36 was reduced by 21% (P=0.0013) following lifestyle intervention, and individual sCD36 reductions were significantly associated with the corresponding decreases in HOMA-IR, triglycerides and total cholesterol. The largest sCD36 decrease occurred among children who reduced HOMA-IR and liver fat. After 12 months of follow-up, sCD36 was increased (P=0.014) and the metabolic improvements were largely lost.

CONCLUSIONS

Weight-loss-induced sCD36 reduction, coincident with improved insulin resistance, circulating lipids and hepatic fat accumulation, proposes that sCD36 may be an early marker of long-term health risk associated with obesity-related complications.

Macrophage activation marker soluble CD163 and non-alcoholic fatty liver disease in morbidly obese patients undergoing bariatric surgery

BACKGROUND AND AIMS

Macrophages play an important role in non-alcoholic fatty liver disease (NAFLD). Soluble CD163 (sCD163) is a specific marker of macrophage activation. We aimed to measure sCD163 in morbidly obese patients with varying degrees of NAFLD before and after bariatric surgery (BS).

METHODS

Demographic, clinical, and biochemical data, and plasma sCD163 measured by enzyme-linked immunosorbent assay, of 196 patients were collected preoperatively and 3, 6, and 12 months after BS leading to significant weight loss. Peroperative liver biopsies were assessed for the NAFLD Activity Score (NAS), Kleiner fibrosis score, and the fatty liver inhibition of progression (FLIP) algorithm. In a subset, CD163 immunohistochemistry and real-time quantitative polymerase chain reaction for CD163 mRNA were performed.

RESULTS

sCD163 was higher in patients with NAS ≥ 5 compared with those with NAS < 5 (2.4(2.0-3.1) vs 1.9(1.5-2.3) mg/L, P < 0.001) and in patients with bridging fibrosis (F ≥ 3) compared with lower fibrosis stages (2.6(2.0-4.9) vs 2.0(1.5-2.4) mg/L, P = 0.001). Preoperative sCD163 was independently associated with both the NAS (P = 0.002) and the fibrosis score (P = 0.024). sCD163 decreased after BS and was greatly reduced after 12 months, more rapidly so in patients with NAS ≥ 5 (P < 0.001) and non-alcoholic steatohepatitis (NASH) according to the FLIP algorithm (P = 0.03). Immunohistochemistry showed CD163-positive macrophages aligning fat-laden hepatocytes and forming microgranulomas in patients with NASH. CD163 mRNA expression did not vary with NAS.

CONCLUSION

sCD163 increased in parallel with the severity of NAFLD in morbid obesity, indicating macrophage activation. BS reduced sCD163 even in patients with severe liver injury and fibrosis, suggesting full reversibility of macrophage activation associated with improved insulin sensitivity.

Evaluation of circulating markers of hepatic apoptosis and inflammation in obese children with and without obstructive sleep apnea

OBJECTIVE

Hepatocyte apoptosis and macrophage activation contribute to the disease progression of nonalcoholic fatty liver disease (NAFLD). Obstructive sleep apnea (OSA) in obese children is associated with the severity of NAFLD. The aim of this study was to evaluate plasma levels of soluble Fas (sFas), soluble Fas ligand (sFasL), cytokeratin 18 (CK18) (markers of apoptosis), and soluble CD163 (sCD163) (marker of macrophage activation) in obese children with and without OSA.

METHODS

Consecutive obese children who were evaluated for OSA were recruited. The diagnosis of OSA was made using overnight polysomnography (PSG). Fasting blood samples were used to determine plasma CK18, sFas, sFasL, and sCD163 levels using specific sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Fifty-eight subjects were included in the analysis with a mean age of 8.9 ± 3.2 years and a mean body mass index (BMI) z-score of 2.4 ± 0.49. Circulating sFas and sFasL levels were significantly lower in subjects with mild and severe OSA compared with those without OSA (p < 0.005 for both). In addition, sCD163 levels increased with an increasing severity of OSA (no OSA = 1.6 ± 0.25 mg/L, mild OSA = 2.3 ± 0.45, and severe OSA = 3.0 ± 0.52; p < 0.001), and they correlated with the apnea-hypopnea index (AHI) [rho (95% confidence interval, CI) of 0.71 (0.41, 1.00), p-value <0.001]. In six patients with severe OSA from whom samples were taken before and after tonsillectomy, the sCD163 level decreased significantly after treatment, and there was a trend toward an increase in sFasL.

CONCLUSION

Markers of apoptosis and macrophage activation are altered in obese children with OSA, indicating increased apoptotic and inflammatory pressures.

Visceral obesity is associated with increased soluble CD163 concentration in men with type 2 diabetes mellitus

Monocyte/macrophage-specific soluble CD163 (sCD163) concentration is associated with insulin resistance and increases with deteriorating glycemic control independently of BMI. This led to the proposal of the hypothesis that obesity-associated white adipose tissue inflammation varies between individuals. The objective was to examine the effect of male overweight/obesity and type 2 diabetes mellitus (T2DM) on associations between adiposity parameters and sCD163. A total of 23 overweight/obese non-diabetic men, 16 overweight/obese men with T2DM, and a control group of 20 normal-weight healthy men were included. Body composition and regional body fat distribution were determined by whole-body dual X-ray absorptiometry scan and abdominal computed tomography (CT) scan. Serum sCD163 concentrations were determined by ELISA. Associations between adiposity parameters and sCD163 were investigated using multiple linear regression analysis. In the normal-weight healthy men, there was no significant association between adiposity parameters and sCD163, whereas in the overweight/obese non-diabetic men, measures of general and regional adiposity were positively associated with sCD163. In the overweight/obese men with T2DM, only visceral adipose tissue (VAT) and the ratio of VAT to abdominal subcutaneous adipose tissue (SAT), a measure of relative body fat distribution between VAT and SAT depots, were positively associated with sCD163. In a multivariate analysis, including VAT, upper-body SAT, and lower-body fat, adjusted for BMI and age, VAT remained a significant predictor of sCD163 in the overweight/obese T2DM men, but not in the overweight/obese non-diabetic men. Our results indicate that VAT inflammation is exaggerated in men with T2DM, and that propensity to store excess body fat viscerally is particularly detrimental in men with T2DM.