Hepatitis C infection and nonalcoholic fatty liver disease

Association of metabolic dysfunction-associated fatty liver disease with gastrointestinal infections: insights from National Inpatient Sample Database

OBJECTIVES

The study aimed to compare the risk of gastrointestinal infections among patients with and without metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

This was a population-based, retrospective, observational study using data from the National Inpatient Sample (NIS), the largest all-payer US inpatient care database.

SETTING

Hospitalisation of adults aged ≥18 years old admitted in 2020 was identified using the NIS. Patients were stratified by the presence and absence of MAFLD.

PARTICIPANTS

26.4 million adults aged ≥18 years old were included in the study. Patients younger than 18 and those with missing demographic or mortality data were excluded.

PRIMARY AND SECONDARY OUTCOMES

Primary outcome was to assess the overall risk of gastrointestinal infections in patients with and without MAFLD. Secondary outcomes were demographics and comorbidities stratified by the presence or absence of gastrointestinal infection, and the risk of specific gastrointestinal pathogens.

RESULTS

Of 26.4 million patients admitted in 2020, 755 910 (2.85%) had the presence of MAFLD. There was a higher prevalence of bacterial gastrointestinal infections in patients with MAFLD than those without (1.6% vs 0.9%, p<0.001). The incidence of Clostridioides difficile (1.3% vs 0.8%, p<0.001), Escherichia coli (0.3% vs 0.01%, p<0.001), and Salmonella (0.07% vs 0.03%, p<0.001) was higher in patients with MAFLD. The presence of MAFLD was associated with higher odds of developing gastrointestinal infections (adjusted OR (aOR) -1.75, 95% CI -1.68 to 1.83, p<0.001). After adjusting for confounders, results remained statistically significant (aOR -1.36, 95% CI - 1.30-1.42, p<0.001).

CONCLUSION

Even after adjusting for confounding factors, our study demonstrates an increased risk of gastrointestinal infections in patients with MAFLD, specifically of C. difficile, E. coli, and Salmonella. The immune and microbiota changes seen within MAFLD potentially contribute to the increased risk of gastrointestinal infections.

The C1q-ApoE complex: A new hallmark pathology of viral hepatitis and nonalcoholic fatty liver disease

We recently identified a high-affinity C1q-ApoE complex in human artery atherosclerotic intima lesions and in human amyloid plaques of Alzheimer's Disease brains defining a common pathogenetic pathway of two diverse diseases, i.e. atherosclerosis and dementia. C1q is the initiating and controlling protein of the classical complement cascade (CCC), which occupies a key role in multiple acute and chronic inflammatory tissue responses. C1q is largely produced by myeloid cells including Kupffer cells (KCs) and subsequently secreted into the circulation as an inactive preprotein. Its binding partner, Apolipoprotein E (ApoE), is produced by KCs and hepatocytes and it is also secreted into the circulation, where it regulates essential steps of lipid transport. In addition to its major source, ApoE can be produced by non-liver cells including immune cells and multiple other cells depending on local tissue contexts. To initiate the CCC cascade, C1q must be activated by molecules as varied as oxidized lipids, amyloid fibrils, and immune complexes. However, ApoE is mute towards inactive C1q but binds at high-affinity to its activated form. Specifically, our studies revealed that ApoE is a CCC-specific checkpoint inhibitor via the formation of the C1q-ApoE complex. We proposed that it may arise in multiple if not all CCC-associated diseases and that its presence indicates ongoing CCC activity. Here, we turned to the liver to examine C1q-ApoE complexes in human B- and C-viral hepatitis and nonalcoholic fatty liver disease (NAFLD). In addition, we used multidrug-resistance-2 gene-knockout (Mdr2-KO) mice as a model for inflammatory liver disease and hepatocellular carcinoma (HCC) pathogenesis. In normal murine and human livers, KCs were the major C1q-producing cell type while hepatocytes were the primary ApoE-forming cell type though the C1q-ApoE complex was rare or nonexistent. However, significant numbers of C1q-ApoE complexes formed in both Mdr2-KO, human viral hepatitis, and NAFLD around portal triads where immune cells had infiltrated the liver. Additionally, high numbers of C1q-ApoE complexes emerged in human livers in areas of extracellular lipid droplets across the entire liver parenchyma in NAFLD-affected patients. Thus, the C1q-ApoE complex is a new pathological hallmark of viral hepatitis B and C and NAFLD.

Comparing the controlled attenuation parameter using FibroScan and attenuation imaging with ultrasound as a novel measurement for liver steatosis

Background/Aims

In a recent study, attenuation imaging (ATI) with ultrasound was used as a new approach for detecting liver steatosis. However, although there are many studies on ATI and controlled attenuation parameter (CAP) that prove their practicability, there are few studies comparing these two methods. As such, this study compared CAP and ATI for the detection and evaluation of liver steatosis.

Methods

A prospective analysis of 28 chronic liver disease patients who underwent liver biopsy, FibroScan® imaging, and ATI with ultrasound was conducted. The presence and degree of steatosis, as measured with the FibroScan® device and ATI, were compared with the pathological results obtained using liver biopsy.

Results

The areas under the receiver operating characteristic curve (AUROC) of ATI and CAP for differentiating between normal and hepatic steatosis were 0.97 (95% confidence interval [CI] 0.83–1.00) and 0.96 (95% CI 0.81–0.99), respectively. ATI has a higher AUROC than CAP does in liver steatosis, at 0.99 (95% CI, 0.86–1.00) versus 0.91 (95% CI, 0.74–0.98) in grade ≥ 2 and 0.97 (95% CI, 0.82–1.00) versus 0.88 (95% CI, 0.70–0.97) in grade = 3, respectively.

Conclusion

The ATI and CAP results showed good consistency and accuracy for the steatosis grading when compared with the liver biopsy results. Moreover, ATI is even better than CAP in patients with moderate or severe steatosis. Therefore, ATI represents a non-invasive and novel diagnostic tool with which to support the diagnosis of liver steatosis in clinical practice.

Infections at the nexus of metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is a chronic liver disease that affects about a quarter of the world population. MAFLD encompasses different disease stadia ranging from isolated liver steatosis to non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis and hepatocellular carcinoma. Although MAFLD is considered as the hepatic manifestation of the metabolic syndrome, multiple concomitant disease-potentiating factors can accelerate disease progression. Among these risk factors are diet, lifestyle, genetic traits, intake of steatogenic drugs, male gender and particular infections. Although infections often outweigh the development of fatty liver disease, pre-existing MAFLD could be triggered to progress towards more severe disease stadia. These combined disease cases might be underreported because of the high prevalence of both MAFLD and infectious diseases that can promote or exacerbate fatty liver disease development. In this review, we portray the molecular and cellular mechanisms by which the most relevant viral, bacterial and parasitic infections influence the progression of fatty liver disease and steatohepatitis. We focus in particular on how infectious diseases, including coronavirus disease-19, hepatitis C, acquired immunodeficiency syndrome, peptic ulcer and periodontitis, exacerbate MAFLD. We specifically underscore the synergistic effects of these infections with other MAFLD-promoting factors.

Attenuation Imaging with Ultrasound as a Novel Evaluation Method for Liver Steatosis

In recent years, ultrasound attenuation imaging (ATI) has emerged as a new method to detect liver steatosis. However, thus far, no studies have confirmed the clinical utility of this technology. Using a retrospective database analysis of 28 patients with chronic liver disease who underwent ultrasound liver biopsy and ATI, we compared the presence and degree of steatosis measured by ATI with the results obtained through liver biopsy. The area under the receiver operating characteristic curve (AUROC) of the ATI for differentiating between normal and hepatic steatosis was 0.97 (95% confidence interval: 0.83–1.00). The AUROC of the ATI was 0.99 (95% confidence interval: 0.86–1.00) in grade ≥2 liver steatosis and 0.97 (95% confidence interval: 0.82–1.00) in grade 3. ATI showed good consistency and accuracy for the steatosis grading of liver biopsy. Therefore, ATI represents a novel diagnostic measurement to support the diagnosis of liver steatosis in non-invasive clinical practice.

A prospective comparative assessment of the accuracy of the FibroScan in evaluating liver steatosis

Background/aims

Recent studies have demonstrated the utility of the FibroScan^® device in diagnosing liver steatosis, but its usefulness has not been thoroughly appraised. We investigated the usefulness of the controlled attenuation parameter (CAP) in detecting and quantifying liver steatosis.

Methods

A prospective analysis was applied to 79 chronic liver disease patients who underwent a liver biopsy, a FibroScan investigation, ultrasonography, and hepatic steatosis index (HSI). The presence and degree of steatosis as measured by the FibroScan device, ultrasonography and HSI were compared with the results for the liver biopsy tissue.

Results

There was substantial concordance between the liver biopsy results and the CAP as evaluated by the kappa (κ) index test for detecting liver steatosis (κ_CAP = 0.77, P<0.001; κ_{ultrasonography} = 0.60, P<0.001; κ_HSI = 0.47, P<0.001). The areas under the receiver operating characteristic curve (AUROCs) of the CAP, ultrasonography, and HSI were 0.899 [95% confidence interval (CI) = 0.826–0.972)], 0.859 (95% CI = 0.779–0.939), and 0.766 (95% CI = 0.655–0.877), respectively. The optimal CAP cutoff value for differentiating between normal and hepatic steatosis was 247 dB/m, which produced sensitivity and specificity values of 91.9% and 85.7%, respectively, as well as a positive predictive value of 85.0% and a negative predictive value of 92.3%.

Conclusion

The CAP produces results that are highly concordant with those of a liver biopsy in detecting steatosis. Therefore, the CAP is a noninvasive and reliable tool for evaluating liver steatosis, even in the early stages.

Prevalence and predictors of low muscle mass in HIV/viral hepatitis coinfection

OBJECTIVE

Low muscle mass is associated with reduced survival in HIV, possibly mediated by systemic inflammation. Viral hepatitis coinfection can induce additional inflammation and hepatic dysfunction that may exacerbate low muscle mass. We determined the prevalence of and risk factors for low muscle mass in HIV/viral hepatitis coinfection.

DESIGN AND METHODS

A cross-sectional study of participants in the Multicenter AIDS Cohort Study and Women's Interagency HIV Study with anthropometry performed after 1 January 2000. Viral hepatitis defined by positive hepatitis B virus surface antigen and/or hepatitis C virus RNA. Low muscle mass defined as less than 10th percentile of age-matched and sex-matched reference values for mid-upper arm circumference. Using multivariable logistic regression, we determined adjusted odds ratios with 95% confidence intervals (CIs) of the association of HIV/viral hepatitis coinfection with low muscle mass and factors associated with low muscle mass in coinfected persons. Analyses adjusted for age, race, BMI, alcohol use, and IDU (also, nadir CD4 cell count and HIV RNA where appropriate).

RESULTS

Among 3518 participants (164 HIV/viral hepatitis, 223 viral hepatitis alone, 1070 HIV alone, and 2061 uninfected), HIV/viral hepatitis-coinfected persons had a 3.50-fold (95% CI, 1.51-8.09), 1.93-fold (1.17-3.20), and 2.65-fold (1.62-4.35) higher odds of low muscle mass than viral hepatitis-monoinfected, HIV-monoinfected, and uninfected persons, respectively. Lack of HIV RNA suppression [odds ratio, 2.26 (95% CI, 1.10-4.63)] was the only factor associated with low muscle mass in coinfected persons.

CONCLUSION

HIV/viral hepatitis-coinfected persons have a higher likelihood of low muscle mass than those with viral hepatitis monoinfection, HIV monoinfection, or neither infection. HIV viremia is an important risk factor for low muscle mass among coinfected persons.

Association between Diabetes Mellitus and Fatty Liver Based on Ultrasonography Screening in the World's Highest Cholangiocarcinoma Incidence Region, Northeast Thailand

Fatty liver disease (FLD) can be a precondition for other liver pathology including cholangiocarcinoma (CCA). Diabetes mellitus (DM) has been suggested in some studies to be a risk factor for FLD as well as cancers, including cholangiocellular carcinoma; however, there are currently very few studies on FLD in DM subjects, although the rate of FLD continues to increase annually. To determine the association between DM and FLD ultrasonographic data were analyzed from the Cholangiocarcinoma Screening and Care Program (CASCAP), in northeast Thailand. DM was reported by the subjects based on the CASCAP health questionnaire. Factors that were associated with FLD were determined by prevalence, odds ratio (ORs) and its 95% confidence intervals (CIs) using multiple logistic regression. There were 45,263 subjects with a mean age of 53.46 (±9.25) years. FLD was found in 36.3% of DM subjects but only in 20.7% of non-DM subjects. The association between DM and FLD was adjusted for all other factors including gender, age, education level, relatives diagnosed with CCA, smoking, alcohol consumption, and hepatitis B and C. The risk of DM in subjects having FLD was highly significant compared with the non-DM subjects (OR 2.13; 95%CI: 1.92 to 2.35; p-value < 0.001). Thus DM is significantly associated with FLD which in turn may facilitate the development of several diseases including CCA. DM should be taken into consideration in future ultrasonic investigations of FLD and CCA.

Radiologic evaluation of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a frequent cause of chronic liver diseases, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH)-related liver cirrhosis. Although liver biopsy is still the gold standard for the diagnosis of NAFLD, especially for the diagnosis of NASH, imaging methods have been increasingly accepted as noninvasive alternatives to liver biopsy. Ultrasonography is a well-established and cost-effective imaging technique for the diagnosis of hepatic steatosis, especially for screening a large population at risk of NAFLD. Ultrasonography has a reasonable accuracy in detecting moderate-to-severe hepatic steatosis although it is less accurate for detecting mild hepatic steatosis, operator-dependent, and rather qualitative. Computed tomography is not appropriate for general population assessment of hepatic steatosis given its inaccuracy in detecting mild hepatic steatosis and potential radiation hazard. However, computed tomography may be effective in specific clinical situations, such as evaluation of donor candidates for hepatic transplantation. Magnetic resonance spectroscopy and magnetic resonance imaging are now regarded as the most accurate practical methods of measuring liver fat in clinical practice, especially for longitudinal follow-up of patients with NAFLD. Ultrasound elastography and magnetic resonance elastography are increasingly used to evaluate the degree of liver fibrosis in patients with NAFLD and to differentiate NASH from simple steatosis. This article will review current imaging methods used to evaluate hepatic steatosis, including the diagnostic accuracy, limitations, and practical applicability of each method. It will also briefly describe the potential role of elastography techniques in the evaluation of patients with NAFLD.

Hepatic fat quantification using chemical shift MR imaging and MR spectroscopy in the presence of hepatic iron deposition: validation in phantoms and in patients with chronic liver disease

PURPOSE

To compare the accuracy of four chemical shift magnetic resonance imaging (MRI) (CS-MRI) analysis methods and MR spectroscopy (MRS) with and without T2-correction in fat quantification in the presence of excess iron.

MATERIALS AND METHODS

CS-MRI with six opposed- and in-phase acquisitions and MRS with five-echo acquisitions (TEs of 20, 30, 40, 50, 60 msec) were performed at 1.5 T on phantoms containing various fat fractions (FFs), on phantoms containing various iron concentrations, and in 18 patients with chronic liver disease. For CS-MRI, FFs were estimated with the dual-echo method, with two T2*-correction methods (triple- and multiecho), and with multiinterference methods that corrected for both T2* and spectral interference effects. For MRS, FF was estimated without T2-correction (single-echo MRS) and with T2-correction (multiecho MRS).

RESULTS

In the phantoms, T2*- or T2-correction methods for CS-MRI and MRS provided unbiased estimations of FFs (mean bias, -1.1% to 0.5%) regardless of iron concentration, whereas the dual-echo method (-5.5% to -8.4%) and single-echo MRS (12.1% to 37.3%) resulted in large biases in FFs. In patients, the FFs estimated with triple-echo (R = 0.98), multiecho (R = 0.99), and multiinterference (R = 0.99) methods had stronger correlations with multiecho MRS FFs than with the dual-echo method (R = 0.86; P ≤ 0.011). The FFs estimated with multiinterference method showed the closest agreement with multiecho MRS FFs (the 95% limit-of-agreement, -0.2 ± 1.1).

CONCLUSION

T2*- or T2-correction methods are effective in correcting the confounding effects of iron, enabling an accurate fat quantification throughout a wide range of iron concentrations. Spectral modeling of fat may further improve the accuracy of CS-MRI in fat quantification.

Variant adiponutrin (PNPLA3) represents a common fibrosis risk gene: non-invasive elastography-based study in chronic liver disease

BACKGROUND & AIMS

Recent genome-wide association studies have identified the variant p.I148M of the adiponutrin gene PNPLA3 as a risk factor for developing severe forms of non-alcoholic and alcoholic liver diseases. The risk allele confers an increased risk for fatty liver disease and elevated serum aminotransferase activities reflecting liver injury. In the current elastography-based study, we investigate variant adiponutrin as genetic determinant of liver fibrosis, the hallmark of all chronic liver diseases.

METHODS

In this observational cross-sectional study, we staged 899 patients with different chronic liver diseases non-invasively by transient elastography (Fibroscan) and genotyped them for variant adiponutrin (rs738409) by PCR-based assays. A subgroup of 229 patients consented to percutaneous liver biopsy, validating the accuracy of elastography in staging fibrosis (ρ=0.743, p<0.01).

RESULTS

Carriers of distinct p.I148M adiponutrin genotypes display significant (p=0.017) differences in liver stiffness determined by elastography. In particular, individuals carrying the allele [G] are at higher risk of developing liver cirrhosis defined by stiffness values ≥13.0kPa (OR=1.56, p=0.005). Of note, the PNPLA3 risk variant advances fibrosis in the total cohort as well as in the subgroups of patients with viral hepatitis and non-viral liver diseases and contributes 16% of the total cirrhosis risk.

CONCLUSIONS

The adiponutrin risk variant is a common genetic determinant of progressive liver fibrosis. Our results underpin non-invasive follow-up for individuals with chronic liver disease at-risk for developing advanced fibrosis and cirrhosis.

Hepatic lipogranulomas in patients with chronic liver disease: Association with hepatitis C and fatty liver disease

AIM: To study the significance and clinical implication of hepatic lipogranuloma in chronic liver diseases, including fatty liver disease and hepatitis C.

METHODS: A total of 376 sequential, archival liver biopsy specimens were reviewed. Lipogranuloma, steatosis and steato-fibrosis were evaluated with combined hematoxylin and eosin and Masson’s trichrome staining.

RESULTS: Fifty-eight (15.4%) patients had lipogranuloma, including 46 patients with hepatitis C, 14 patients with fatty liver disease, and 5 patients with other diseases. Hepatic lipogranuloma was more frequently seen in patients with hepatitis C (21%) and fatty liver disease (18%), and its incidence was significantly higher than that in control group (P < 0.0002 and P < 0.007, respectively). In addition, 39 out of the 58 patients with lipogranuloma were associated with steatosis and/or steato-fibrosis. Of the 18 lipogranuloma patients with clinical information available for review, 15 (83%) had risk factors associated with fatty liver disease, such as alcohol use, obesity, hyperlipidemia, and diabetes mellitus. Although the incidence of these risk factors was greater in patients with lipogranuloma than in control group (60%), it did not reach statistical significance.

CONCLUSION: Hepatic lipogranuloma is not limited to mineral oil use and commonly associated with hepatic steatosis, hepatitis C and fatty liver disease. With additional histological features of steato-fibrosis, lipogranuloma can also be used as a marker of prior hepatic steatosis.

Fat: A matter of disturbance for the immune system

Obesity is increasingly being recognized as a risk factor for a number of benign and malignant gastrointestinal conditions. However, literature on the underlying pathophysiological mechanisms is sparse and ambiguous. There is compelling evidence that both overnutrition and undernutrition negatively interfere with the immune system. Overnutrition has been found to increase susceptibility to the development of inflammatory diseases, autoimmune diseases and cancer. In the regulation of immune and inflammatory processes, white adipose tissue plays a critical role, not only as an energy store but also as an important endocrine organ. The obese state is characterised by a low-grade systemic inflammation, mainly as a result of increased adipocytes as well as fat resident- and recruited-macrophage activity. In the past few years, various products of adipose tissue including adipokines and cytokines have been characterised and a number of pathways linking adipose tissue metabolism with the immune system have been identified. Activation of the innate immune system plays a major role in hepatic steatosis. Non-alcoholic fatty liver disease includes a wide spectrum of diseases, from pure steatosis to non-alcoholic steatohepatitis in the absence of significant alcohol consumption. Although steatosis is considered a non-progressive disease, non-alcoholic steatohepatitis may deteriorate in advanced chronic liver diseases, cirrhosis, and hepatocellular carcinoma. An important parallel between obesity-related pathology of adipose tissue and liver pertains to the emerging role of macrophages, and growing evidence suggests that Kupffer cells critically contribute to progression of non-alcoholic fatty liver disease. Moreover, a close link between specific immune activation and atherosclerosis has been well established, suggesting that fat can directly trigger immune responses. This review discusses the role of fat as “a matter of disturbance for the immune system” with a focus on hepatic steatosis.

Effects of metabolic syndrome on the outcomes of chronic viral hepatitis and mechanisms involved

Chronic hepatitis virus infection can result in liver dysfunction, cirrhosis and hepatocellular carcinoma and is therefore a serious public health matter. With the alteration of people's living habits, the prevalence of metabolic syndrome is gradually increasing. Metabolic syndrome, especially fatty liver disease, may be one of risk factors for aggravation of liver injury, poor prognosis, and poor response to antiviral therapy in patients with chronic viral hepatitis.

Non-invasive assessment of hepatic steatosis: prospective comparison of the accuracy of imaging examinations

BACKGROUND & AIMS

Despite increasing use of various imaging examinations for non-invasive assessment of hepatic steatosis (HS), their relative accuracy is unknown. The objective of this study is to prospectively compare the accuracy of computed tomography (CT), dual gradient echo magnetic resonance imaging (DGE-MRI), proton magnetic resonance spectroscopy ((1)H-MRS), and ultrasonography (US) for the diagnosis and quantitative estimation of HS.

METHODS

A total of 161 consecutive potential living liver donors underwent US (performed by two independent radiologists, US1 and US2), CT, DGE-MRI, (1)H-MRS, and liver biopsy on the same day. Using the histologic degree of HS as the reference standard, we compared the diagnostic performance of US1, US2, CT, DGE-MRI, and (1)H-MRS for diagnosing HS >or= 5% and HS >or= 30% and compared the accuracy of CT, DGE-MRI, and (1)H-MRS in the quantitative estimation of HS.

RESULTS

DGE-MRI and (1)H-MRS significantly outperformed CT and US for the diagnosis of HS5%. DGE-MRI showed a tendency of higher accuracy than the other examinations for diagnosing HS >or= 30%. The cross-validated sensitivity and specificity of DGE-MRI at the optimal cut-off were 76.7% and 87.1%, respectively, for diagnosing HS >or= 5% and 90.9% and 94%, respectively, for diagnosing HS >or= 30%. The cross-validated Bland-Altman 95% limits of agreement between the estimated degree of HS on imaging examinations and the histologic degree of HS, were the narrowest with DGE-MRI, yielding -12.7% to 12.7%.

CONCLUSIONS

Among CT, DGE-MRI, (1)H-MRS, and US, DGE-MRI is the most accurate method for the diagnosis and quantitative estimation of HS. Therefore, DGE-MRI may be the preferred imaging examination for the non-invasive assessment of HS.

Gene expression profile associated with superimposed non-alcoholic fatty liver disease and hepatic fibrosis in patients with chronic hepatitis C

BACKGROUND

Hepatic steatosis occurs in 40-70% of patients chronically infected with hepatitis C virus [chronic hepatitis C (CH-C)]. Hepatic steatosis in CH-C is associated with progressive liver disease and a low response rate to antiviral therapy.

AIM

Gene expression profiles were examined in CH-C patients with and without hepatic steatosis, non-alcoholic steatohepatitis (NASH) and fibrosis.

METHODS

This study included 65 CH-C patients who were not receiving antiviral treatment. Total RNA was extracted from peripheral blood mononuclear cells, quantified and used for one-step reverse transcriptase-polymerase chain reaction to profile 153 mRNAs that were normalized with six 'housekeeping' genes and a reference RNA. Multiple regression and stepwise selection assessed differences in gene expression and the models' performances were evaluated.

RESULTS

Models predicting the grade of hepatic steatosis in patients with CH-C genotype 3 involved two genes: SOCS1 and IFITM1, which progressively changed their expression level with the increasing grade of steatosis. On the other hand, models predicting hepatic steatosis in non-genotype 3 patients highlighted MIP-1 cytokine encoding genes: CCL3 and CCL4 as well as IFNAR and PRKRIR. Expression levels of PRKRIR and SMAD3 differentiated patients with and without superimposed NASH only in the non-genotype 3 cohort (area under the receiver operating characteristic curve=0.822, P-value 0.006]. Gene expression signatures related to hepatic fibrosis were not genotype specific.

CONCLUSIONS

Gene expression might predict moderate to severe hepatic steatosis, NASH and fibrosis in patients with CH-C, providing potential insights into the pathogenesis of hepatic steatosis and fibrosis in these patients.

Adipokines in liver diseases

Adipokines are polypeptides secreted in the adipose tissue in a regulated manner. While some of these molecules are expressed only by adipocytes, resident and infiltrating macrophages and components of the vascular stroma markedly contribute to expression of other adipokines. As a result, adipose tissue inflammation is associated with a modification in the pattern of adipokine secretion. Leptin, adiponectin, and resistin are the best-studied molecules in this class, but cytokines such as tumor necrosis factor or interleukin-6 are also secreted at high levels by the adipose tissue. Several other molecules have been recently identified and are actively investigated. Adipokines interfere with hepatic injury associated with fatty infiltration, differentially modulating steatosis, inflammation, and fibrosis. Several studies have investigated plasma levels of adiponectin in patients with nonalcoholic fatty liver disease, to establish correlations with the underlying state of insulin resistance and with the type and severity of hepatic damage. Hepatitis C is another disease where adipokines may represent a link between viral infection, steatosis, and metabolic disturbances. Identification of the mediators secreted by expanded adipose tissue and their pathogenic role is pivotal in consideration of the alarming increase in the prevalence of obesity and of the detrimental role that this condition exerts on the course of liver diseases.

Kupffer cells in non-alcoholic fatty liver disease: the emerging view

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver disorder of our times. Simple steatosis, a seemingly innocent manifestation of NAFLD, may progress into steatohepatitis and cirrhosis, but this process is not well understood. Since NAFLD is associated with obesity and insulin resistance, mechanisms that link lipid metabolism to inflammation offer insights into the pathogenesis. An important parallel between obesity-related pathology of adipose tissue and liver pertains to the emerging role of macrophages and evidence is growing that Kupffer cells critically contribute to progression of NAFLD. Toll-like receptors, in particular TLR4, represent a major conduit for danger recognition linked to Kupffer cell activation and this process may be perturbed at multiple steps in NAFLD. Steatosis may interfere with sinusoid microcirculation and hepatocellular clearance of microbial and host-derived danger signals, enhancing responsiveness of Kupffer cells. Altered lipid homeostasis in NAFLD may unfavourably affect TLR4 receptor complex assembly and sorting, interfere with signalling flux redistribution, promote amplification loops, and impair negative regulation including alternative activation of Kupffer cells. These events are further promoted by altered adipokine secretion and reactive oxygen species production. Specific targeting of these interactions may provide more effective strategies in the treatment of NAFLD.