Discrimination of lipid composition and cellular localization in human liver tissues by stimulated Raman scattering microscopy

Significance

The molecular mechanisms driving the progression from nonalcoholic fatty liver (NAFL) to fibrosing steatohepatitis (NASH) are insufficiently understood. Techniques enabling the characterization of different lipid species with both chemical and spatial information can provide valuable insights into their contributions to the disease progression.

Aim

We extend the utility of stimulated Raman scattering (SRS) microscopy to characterize and quantify lipid species in liver tissue sections from patients with NAFL and NASH.

Approach

We applied a dual-band hyperspectral SRS microscopy system for imaging tissue sections in both the C-H stretching and fingerprint regions. The same sections were imaged with polarization microscopy for detecting birefringent liquid crystals in the tissues.

Results

Our imaging and analysis pipeline provides accurate classification and quantification of free cholesterol, saturated cholesteryl esters (CEs), unsaturated CE, and triglycerides in liver tissue sections. The subcellular resolution enables investigations of the heterogeneous distribution of saturated CE, which has been under-examined in previous studies. We also discovered that the birefringent crystals, previously found to be associated with NASH development, are predominantly composed of saturated CE.

Conclusions

Our method allows for a detailed characterization of lipid composition in human liver tissues and enables further investigation into the potential mechanism of NASH progression.

sTREM2 is a plasma biomarker for human NASH and promotes hepatocyte lipid accumulation

BACKGROUND

Pathogenetic mechanisms of the progression of NAFL to advanced NASH coupled with potential noninvasive biomarkers and novel therapeutic targets are active areas of investigation. The recent finding that increased plasma levels of a protein shed by myeloid cells -soluble Triggering Receptor Expressed on Myeloid cells 2 (sTREM2) -may be a biomarker for NASH has received much interest. We aimed to test sTREM2 as a biomarker for human NASH and investigate the role of sTREM2 in the pathogenesis of NASH.

METHODS

We conducted studies in both humans (comparing patients with NASH vs. NAFL) and in mice (comparing different mouse models of NASH) involving measurements of TREM2 gene and protein expression levels in the liver as well as circulating sTREM2 levels in plasma. We investigated the pathogenetic role of sTREM2 in hepatic steatosis using primary hepatocytes and bone marrow derived macrophages.

RESULTS

RNA sequencing analysis of livers from patients with NASH or NAFL as well as livers from 2 mouse models of NASH revealed elevated TREM2 expression in patients/mice with NASH as compared with NAFL. Plasma levels of sTREM2 were significantly higher in a well-characterized cohort of patients with biopsy-proven NASH versus NAFL (area under receiver-operating curve 0.807). Mechanistic studies revealed that cocultures of primary hepatocytes and macrophages with an impaired ability to shed sTREM2 resulted in reduced hepatocyte lipid droplet formation on palmitate stimulation, an effect that was counteracted by the addition of exogenous sTREM2 chimeric protein. Conversely, exogenous sTREM2 chimeric protein increased lipid droplet formation, triglyceride content, and expression of the lipid transporter CD36 in hepatocytes. Furthermore, inhibition of CD36 markedly attenuated sTREM2-induced lipid droplet formation in mouse primary hepatocytes.

CONCLUSIONS

Elevated levels of sTREM2 due to TREM2 shedding may directly contribute to the pathogenesis of NAFLD by promoting hepatocyte lipid accumulation, as well as serving as a biomarker for distinguishing patients with NASH versus NAFL. Further investigation of sTREM2 as a clinically useful diagnostic biomarker and of the therapeutic effects of targeting sTREM2 in NASH is warranted.

Genetic deletion or pharmacologic inhibition of the Nlrp3 inflammasome did not ameliorate experimental NASH

It has been postulated that inflammasomes, in particular the NLRP3 (NLR family pyrin domain containing 3) inflammasome, mediate the necroinflammation and fibrosis that characterize nonalcoholic steatohepatitis (NASH) by engaging innate immune responses. We aimed to investigate the impact of genetic deletion or pharmacologic inhibition of the NLRP3 inflammasome on experimental steatohepatitis. Global Nlrp3 KO (expected to inhibit the NLRP3 inflammasome) or Casp1 KO (expected to inhibit all inflammasomes) mice were compared to wild type controls after 6 months on a high-fat, high-cholesterol (HFHC, 1% cholesterol) diet known to induce fibrosing steatohepatitis. Additionally, wildtype mice on a HFHC diet (0.75% or 0.5% cholesterol) for 6 months were either treated or not treated with an oral, pharmacologic inhibitor of Nlrp3 (MCC950) that was delivered in the drinking water (0.3 mg/ml). We found that genetic deletion or pharmacologic inhibition of the NLRP3 inflammasome did not ameliorate any of the histological components of fibrosing NASH in HFHC-fed mice. Collectively, these results do not support NLRP3 inhibition as a potential target for human NASH.

The Assessment of the Diagnostic Accuracy of Antigen-Detecting Rapid Diagnostic Test using Nasopharyngeal Swab Specimen in Detecting SARS-CoV-2 among Patients in a Private Hospital in Bulacan, Philippines

Introduction/Objective

Continuous progression of the COVID-19 outbreak prompted an expensive, limited, and slow-moving laboratory-based molecular testing capacity of the gold standard, Real-time Reverse Transcription- Polymerase Chain Reaction (rRT-PCR), in detecting SARS-CoV-2. The vital step in mitigation is utilizing an accurate diagnostic detection assay to deploy various preventive measures. Therefore, there is a need to evaluate an accessible, fast, and inexpensive point-of-care immunoassay, such as Antigen-detecting Rapid Diagnostic Tests (Ag- RDTs). Thus, the study aimed to assess the diagnostic accuracy of Ag-RDT in detecting SARS-CoV-2.

Methods/Case Report

A non-experimental, quantitative, and cross-sectional cohort study utilized 272 SARS-CoV-2 Ag-RDT with rRT-PCR confirmation collected from April 2021 to February 2022 in a private primary hospital laboratory database in Bulacan, Philippines. Diagnostic accuracy parameters of Ag-RDT included in the study are sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

Results (if a Case Study enter NA)

The overall sensitivity and specificity of Ag-RDT were 69.6% and 98.8%, respectively. Additionally, it exhibited a PPV of 84.2% and an NPV of 97.2%. With a hypothetical 1% prevalence, PPV and NPV were 36.8% and 99.7%. Meanwhile, PPV and NPV were 86.5% and 96.7% at 10% prevalence. High specificity denotes that positive Ag-RDT test results can be confidently considered in true SARS-CoV-2 infection, while low sensitivity entails that a negative result must be subjected to confirmatory tests. Furthermore, when prevalence increases, PPV increases while NPV decreases.

Conclusion

The study primarily encapsulated that the Ag-RDT cannot replace rRT-PCR in detecting SARS-CoV-2 infections. Despite its shortcomings, Ag-RDT is still valuable in areas with moderate-to-high disease prevalence and with limited access to confirmatory test due to its high predictive values and advantages. A larger number of positive results of rRT-PCR, evaluation of factors correlating to low sensitivity, and a prospective study are recommended for future studies.

Systemic proinflammatory-profibrotic response in aortic stenosis patients with diabetes and its relationship with myocardial remodeling and clinical outcome

Background

It is unclear whether and how diabetes mellitus may aggravate myocardial fibrosis and remodeling in the pressure-overloaded heart. We investigated the impact of diabetes on the prognosis of aortic stenosis (AS) patients and its underlying mechanisms using comprehensive noninvasive imaging studies and plasma proteomics.

Methods

Severe AS patients undergoing both echocardiography and cardiovascular magnetic resonance (CMR) (n=253 of which 66 had diabetes) comprised the imaging cohort. The degree of replacement and diffuse interstitial fibrosis by late gadolinium enhancement (LGE) and extracellular volume fraction (ECV) was quantified using CMR. Plasma samples were analyzed with the multiplex proximity extension assay for 92 proteomic biomarkers in a separate biomarker cohort of severe AS patients (n=100 of which 27 had diabetes).

Results

In the imaging cohort, diabetic patients were older (70.4±6.8 vs. 66.7±10.1 years) and had a higher prevalence of ischemic heart disease (28.8% vs. 9.1%), with more advanced ventricular diastolic dysfunction. On CMR, diabetic patients had increased replacement and diffuse interstitial fibrosis (LGE% 0.3 [0.0–1.6] versus 0.0 [0.0–0.5], p=0.009; ECV% 27.9 [25.7–30.1] versus 26.7 [24.9–28.5], p=0.025) (Figure 1).

Plasma proteomics analysis of the biomarker cohort revealed that 9 proteins (E-selectin, interleukin-1 receptor type 1, interleukin-1 receptor type 2, galectin-4, intercellular adhesion molecule 2, integrin beta-2, galectin-3, growth differentiation factor 15, and cathepsin D) are significantly elevated in diabetic AS patients (Figure 2). Pathway over-representation analyses of the plasma proteomics with Gene Ontology terms indicated that pathways related to inflammatory response and extracellular matrix components were enriched, suggesting that diabetes is associated with systemic effects that evoke proinflammatory and profibrotic response to the pressure-overloaded myocardium.

During follow-up (median 6.3 years [IQR 5.2–7.2]) of the imaging cohort, 232 patients received aortic valve replacement (AVR) with 53 unexpected heart failure admissions or death. Diabetes was a significant predictor of heart failure and death, independent of clinical covariates and AVR (hazard ratio 1.88, 95% confidence interval 1.06–3.31, p=0.030).

Conclusion

Plasma proteomic analyses indicate that diabetes potentiates the systemic proinflammatory and profibrotic milieu in AS patients. These systemic biological changes underlie the increase of myocardial fibrosis, diastolic dysfunction, and worse clinical outcomes in severe AS patients with concomitant diabetes.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): National Research Foundation of Korea

Augmented risk of ischemic stroke in hypertrophic cardiomyopathy patients without documented atrial fibrillation

Background

Ischemic stroke is a common complication in patients with hypertrophic cardiomyopathy (HCM) (1). Although atrial fibrillation (AF) is a well-established risk factor for ischemic stroke in HCM, the risk of ischemic stroke in patients with HCM without documented AF is less recognized (1, 2). This study aimed to determine the risk of ischemic stroke and identify its risk factors in patients with HCM without documented AF.

Methods

This nationwide population-based cohort study used the Korean National Health Insurance database. After excluding patients with a prior history of AF, thromboembolic events, cancer, or the use of anticoagulants, we identified 8,328 HCM patients without documented AF and 1:2 propensity score-matched 16,656 non-HCM controls. The clinical outcome was an incident ischemic stroke.

Results

During a mean follow-up of approximately 6 years, ischemic stroke occurred in 328/8,328 (3.9%) patients with HCM and 443/16,656 (2.7%) controls. Among individuals who developed ischemic stroke, the proportion of AF concomitantly detected accounted for 26.5% (87/328) and 5.8% (26/443) in the HCM and control groups, respectively. The overall incidence of ischemic stroke was 0.716/100 person-years in the HCM group, which was significantly higher than that in the control group (0.44/100 person-years) (HR 1.643; 95% CI, 1.424–1.895; P<0.001, Figure 1). The subgroup analysis according to age, sex, and comorbidities (chronic heart failure, hypertension, dyslipidemia, and vascular disease) consistently demonstrated a higher risk of ischemic stroke in the HCM group (P for interaction >0.05). In the HCM group, age ≥65 years (adjusted hazard ratio [HR] 2.741; 95% confidence interval [CI], 2.156–3.486; P<0.001) and chronic heart failure (adjusted HR 1.748; 95% CI, 1.101–2.745; P=0.018) were independent risk factors for ischemic stroke. Overall incidence was 1.360/100 in patients with HCM aged ≥65 and 2.315/100 person-years years in those with chronic heart failure, respectively. Also, compared to controls aged <65 years and without CHF, adjusted HR for ischemic stroke was 4.756 (95% CI 3.807–5.867) in patients with HCM aged ≥65 years and 2.539 (95% CI 1.638–3.936) in those with CHF, respectively (Figure 2).

Conclusions

Patients with HCM without documented AF are at a higher risk of ischemic stroke than the propensity score-matched general population. Age ≥65 years and chronic heart failure are two strong independent risk factors for ischemic stroke in this population.

Funding Acknowledgement

Type of funding sources: None.

Pcsk9 Deletion Promotes Murine Nonalcoholic Steatohepatitis and Hepatic Carcinogenesis: Role of Cholesterol

Proprotein convertase subtilisin/kexin type 9 (Pcsk9) binds to hepatic low-density lipoprotein receptor (LDLR) and induces its internalization and degradation. Pcsk9 inhibition increases LDLR expression by hepatocytes, which causes increased uptake of circulating LDL, thereby reducing plasma LDL-cholesterol. However, by increasing the uptake of LDL by the liver, Pcsk9 inhibition increases the exposure of the liver to cholesterol, which may result in higher risk of steatohepatitis and ever carcinogenesis. We compared Pcsk9-/- knockout (KO) mice and appropriate wild-type (WT) controls of the same strain assigned to a high-fat (15%, wt/wt) diet for 9 months supplemented with 0.25%, 0.5%, or 0.75% dietary cholesterol. Pcsk9 KO mice on a high-fat, high-cholesterol diet exhibited higher levels of hepatic free cholesterol loading and hepatic cholesterol crystallization than their WT counterparts. Pcsk9 KO mice developed crown-like structures of macrophages surrounding cholesterol crystal-containing lipid droplets and hepatocytes, exhibited higher levels of apoptosis, and developed significantly more hepatic inflammation and fibrosis consistent with fibrosing steatohepatitis, including 5-fold and 11-fold more fibrosis at 0.5% and 0.75% dietary cholesterol, respectively. When injected with diethylnitrosamine, a hepatic carcinogen, early-in-life Pcsk9 KO mice were more likely to develop liver cancer than WT mice. Conclusion: Pcsk9 KO mice on high-cholesterol diets developed increased hepatic free cholesterol and cholesterol crystals and fibrosing steatohepatitis with a higher predisposition to liver cancer compared with WT mice. Future studies should evaluate whether patients on long-term treatment with anti-PSCK9 monoclonal antibodies are at increased risk of hepatic steatosis, steatohepatitis or liver cancer, while accounting for concurrent use of statins.

P1274 Early surgery versus watchful waiting in patients with moderate aortic stenosis and left ventricular systolic dysfunction

Background

Aortic stenosis (AS) induces significant pressure overload to the left ventricle (LV) and its burden may increase if there is concomitant LV systolic dysfunction. Severe AS with LV systolic dysfunction is a class I indication for aortic valve replacement (AVR) irrespective of symptoms, however, this recommendation is not well established in those with moderate AS and LV systolic dysfunction. In this study, we sought to investigate the clinical impact of surgical AVR among patients with moderate AS and LV systolic dysfunction.

Methods

From 2001 to 2017, we retrospectively but consecutively identified patients with moderate AS and LV systolic dysfunction from a single tertiary hospital. Moderate AS was defined as aortic valve area between 1.0 and 1.5cm2 and LV systolic dysfunction as LV ejection fraction less than 50%. The primary outcome was all-cause death and we additionally analyzed cardiac death as a secondary endpoint. The outcomes were compared between those who underwent early surgical AVR at the stage of moderate AS versus those who were followed without AVR at the outpatient clinic.

Results

Among a total of 257 patients with moderate AS and concomitant LV systolic dysfunction (70.0 ± 11.3 years, 63.4% of male), 34 patients received early AVR. Patients in the AVR group was younger than the observation group (64.2 ± 8.1 vs. 70.9 ± 11.5, respectively), and had a lower prevalence of hypertension and chronic kidney disease. During a mean of 3-year follow up, 112 patients (47.5%) died and the overall death rate was 15.367 per 100 person-year (PY). The AVR group showed a significantly lower rate of all-cause death than the observation group (5.241PY vs. 18.160PY, p-value = 0.002). After multivariable Cox proportional hazard regression adjusting for age, sex, comorbidities and laboratory data, early AVR at the stage of moderate AS significantly reduced the risk of all-cause death (hazard ratio [HR] 0.340, 95% confidence interval [CI] 0.117 - 0.985, p-value = 0.047). However, there was no risk reduction of cardiac death (HR 0.578 95% CI 0.150 - 2.231, p-value = 0.426).

Conclusions

In patients with moderate AS and LV systolic dysfunction, AVR reduces the risk of all-cause death. A prospective design study is warranted to confirm our findings in the near future.

Abstract P1274 Figure. Kaplan-Meier curves for deaths

P1603 Changes of cardiac function in cirrhotic patients after liver transplantation

Funding Acknowledgements

This study was supported by the grant of CJ healthcare 2016 research fund.

Background

Liver cirrhosis (LC) has been known to affect cardiovascular performance. Limited study have evaluated the alteration of myocardial function in patients with LC after liver transplantation (LT).

Purpose

The aim of study was to evaluate changes of cardiac function in patients with cirrhosis following LT using conventional and speckle-tracking echocardiography and late gadolinium enhancement (LGE) of cardiac magnetic resonance (MR).

Methods

Thirty-five patients with cirrhosis (mean age, 57.1 ± 9.0; male, 75%) who were listed for LT were prospectively enrolled. Patients underwent conventional, speckle-tracking echocardiography, and cardiac MR imaging with LGE. Echocardiography and cardiac MR were performed at pre and 1 year after LT. Cirrhotic patients were compared with normal control (n = 20, mean age, 65.0 ± 14.8; men, 11(55%)) and echocardiographic and cardiac MR data were compared pre and post LT.

Results

Conventional and speckle-tracking echocardiography and Cardiac MR imaging demonstrated hyperdynamic left ventricular (LV) function in patients with cirrhosis (LV ejection fraction (EF) with cardiac MR 67.8 ± 7.0% in LC vs. 63.4 ± 6.4% in control, P = 0.028; global longitudinal strain (GLS) -24.3 ± 2.6% in LC vs. -18.6 ± 2.2% in control, P < 0.001). There were no LGE in patients with cirrhosis and no significant differences in LV size, LV wall thickness, LV mass index, and diastolic function between cirrhotic patients and control group (all P > 0.1). Corrected QT interval (QTc) in electrocardiogram was prolonged in LC patients (P < 0.001). One-year after LT, LV end-diastolic diameter and LV end-diastolic volume significantly decreased (P = 0.016 and 0.022, respectively). Although LVEF showed no significant changes 1 year post-LT (P = 0.362), LV-GLS (from -24.7 ± 1.8% to -20.8 ± 3.4%, P < 0.001) significantly decreased. QTc interval also decreased 1 year after LT (from 470.4 ± 29.6msec to 428.2 ± 31.6msec, P = 0.001).

Conclusions

The present study demonstrated that cirrhotic patients showed hyperdynamic circulation and prolonged QTc interval compared with normal controls. After 1 year LT, LV size reduced and augmented LV function was normalized. Given that no LGE in cardiac MR and normalized GLS and QTc after LT, cardiac dysfunction in LC patients could be reversed by LT.

P1368 Effect of angiotensin receptor blocker in patients with moderate or severe aortic stenosis: a randomized controlled trial

Funding Acknowledgements

This study was supported by grants from Boryung Pharmacy Research Fund.

Background/Introduction: Pathophysiology of aortic stenosis (AS) and several previous studies suggested the potential role of angiotensin receptor blocker (ARB) in patients with AS.

Purpose

We aimed to investigate the effects of Fimasartan, an ARB, on exercise capacity and progression of AS in patients with moderate to severe AS.

Methods

We conducted a prospective, randomized, double-blind, placebo-controlled trial in 32 normotensive or controlled-hypertensive patients with moderate or severe AS. Study participants were randomized to Fimasartan 30 mg to 60 mg daily (n = 14) or placebo (n = 18) for 1 year, and underwent cardiopulmonary exercise test, 6-minute walk test, and echocardiography at 0, 6, and 12 months, with follow-up data available in 29 subjects.

Results

Significant reductions in blood pressures were observed in the Fimasartan group but not in the placebo group. Two of the 14 patients in the Fimasartan group withdrew the study due to mild symptoms probably related with the decreased blood pressure, and one patient decline the study protocol. After the 12-month treatment, the peak oxygen consumption (VO2; the primary outcome) in the Fimasartan group was significantly decreased (from 28.3 ± 5.9 to 25.4 ± 3.8 mL/min/kg, P = 0.021) but not in the placebo group (P for interaction = 0.046) (Figure 1A). The severity of AS showed a gradual progression in both groups, without inter-group differences (mean transaortic pressure; Fimasartan group, +4.0 ± 3.8 mmHg/year; placebo group, +5.3 ± 6.2 mmHg/year; P for interaction = 0.429) (Figure 1B). Parameters of left ventricular systolic and diastolic function did not change in both groups.

Conclusions

The use of ARB impaired exercise capacity in patients with moderate or severe AS, and did not prevent the progression of AS. However, due to the small number of participants, further studies are required to confirm these findings.

Abstract P1368 Figure.

P785 Left ventricular geometry and myocardial contractility modulate impact of statins on prognosis in patients with acute heart failure

Funding Acknowledgements

N/A

Background/Introduction: The benefit of statins in patients with heart failure (HF) remains controversial and the mechanism of action is largely speculative. We investigated whether survival benefit with statins differs according to left ventricular (LV) geometry and myocardial contractility in acute HF patients.

Methods

We enrolled 1792 acute HF patients receiving statins and 2296 patients not receiving statins admitted from 2009 to 2016. The LV and right ventricular (RV) global longitudinal strain (GLS) was assessed as a measure of myocardial contractility. Patients were classified into 2 groups based on ischemic etiology of HF and further divided into 4 subgroups according to the median values of LV-GLS or RV-GLS. The primary outcome was 5-year all-cause mortality. The study protocol was approved by the ethics committee at each institute and complied with the Declaration of Helsinki. The need for written informed consent was waived.

Results

During the 5-year follow-up, 1740 (40.4%) patients died and they had more unfavorable baseline characteristics. Statin therapy was significantly associated with improved survival in overall patients and in both groups with and without ischemic etiology (all p <0.001). Patients with concentric remodeling/hypertrophy and eccentric hypertrophy demonstrated survival benefit with statin therapy (P = 0.033, 0.004, and 0.008, respectively), while those with normal geometry did not (p = 0.123). In the non-ischemic HF group, survival benefit with statin therapy was confined to patients with low LV-GLS (p = 0.045) or those with low RV-GLS p = 0.003). On the contrary, in ischemic HF group, survival benefit with statin therapy was observed in all patients regardless of the values of LV-GLS or RV-GLS. Significant interactions were present between statin use and diabetes mellitus and IHD (p for interaction = 0.027 and 0.003, respectively) regarding mortality.

Conclusions

LV geometry and myocardial contractility may modulate the effects of statins in patients with acute HF. These echocardiographic measures can provide prognostic information to guide tailored statin treatment in this population. Our findings may also help to develop more well-designed prospective studies, in terms of a more homogenous study population, to confirm survival benefit with statin therapy.

Abstract P785 Figure. Multivariate Cox survival curves

Cholesterol Crystals in Hepatocyte Lipid Droplets Are Strongly Associated With Human Nonalcoholic Steatohepatitis

It is unclear what drives the development of fibrosing nonalcoholic steatohepatitis (NASH). We aimed to determine whether cholesterol crystallization within hepatocyte lipid droplets (LDs) distinguishes patients with fibrosing NASH from patients with isolated hepatic steatosis and to study pathways leading to cholesterol accumulation in hepatocyte LDs. Patients with fibrosing NASH (n = 16) were compared to patients with isolated steatosis (n = 14). Almost all patients with fibrosing NASH had free cholesterol staining by filipin (16/16) and cholesterol crystals (15/16) in hepatocyte LDs, mostly in association with the LD membrane, compared to only 3/14 with cholesterol crystals and 3/14 with faint filipin staining in patients with isolated steatosis (P < 0.05). We were unable to identify significant differences in the expression of genes in liver tissue related to cholesterol homeostasis or LD proteins between patients with fibrosing NASH and isolated steatosis. Human hepatoma cell line (HepG2) cells were supplemented with low-density lipoprotein (LDL)-cholesterol and oleic acid to develop large LDs, similar to those observed in patients with NASH. Fluorescent markers were used to track the uptake and intracellular trafficking of LDL-cholesterol. LDL-cholesterol was taken up by HepG2 cells and transported through the endosomal-lysosomal compartment directly to LDs, suggesting direct contact sites between late endosomes and LDs. Exposure of HepG2 cells to LDL-cholesterol resulted in a high concentration of cholesterol and cholesterol crystallization in LDs. Conclusion: Excess cholesterol is stored in the liver primarily within hepatocyte LDs where it can crystallize. Our findings are best explained by direct transport of cholesterol from late endosomes/lysosomes to LDs in hepatocytes. We found a strong association between the presence of LD cholesterol crystals and the development of fibrosing NASH in humans, suggesting a causal relationship.

Cholesterol crystallization within hepatocyte lipid droplets and its role in murine NASH

We recently reported that cholesterol crystals form in hepatocyte lipid droplets (LDs) in human and experimental nonalcoholic steatohepatitis. Herein, we assigned WT C57BL/6J mice to a high-fat (15%) diet for 6 months, supplemented with 0%, 0.25%, 0.5%, 0.75%, or 1% dietary cholesterol. Increasing dietary cholesterol led to cholesterol loading of the liver, but not of adipose tissue, resulting in fibrosing steatohepatitis at a dietary cholesterol concentration of ≥0.5%, whereas mice on lower-cholesterol diets developed only simple steatosis. Hepatic cholesterol crystals and crown-like structures also developed at a dietary cholesterol concentration ≥0.5%. Crown-like structures consisted of activated Kupffer cells (KCs) staining positive for NLRP3 and activated caspase 1, which surrounded and processed cholesterol crystal-containing remnant LDs of dead hepatocytes. The KCs processed LDs at the center of crown-like structures in the extracellular space by lysosomal enzymes, ultimately transforming into lipid-laden foam cells. When HepG2 cells were exposed to LDL cholesterol, they developed cholesterol crystals in LD membranes, which caused activation of THP1 cells (macrophages) grown in coculture; upregulation of TNF-alpha, NLRP3, and interleukin 1beta (IL1β) mRNA; and secretion of IL-1beta. In conclusion, cholesterol crystals form on the LD membrane of hepatocytes and cause activation and cholesterol loading of KCs that surround and process these LDs by lysosomal enzymes.

Gallstones: new insights into an old story

Gallstones, particularly cholesterol gallstones, are common in Western populations and may cause symptoms such as biliary colic or complications such as acute cholecystitis or gallstone pancreatitis. Recent studies have allowed for a better understanding of the risk of symptoms or complications in patients with gallstones. In addition, newer data suggest an association of gallstones with overall mortality, cardiovascular disease, gastrointestinal cancers, and non-alcoholic fatty liver disease. Knowledge of appropriate indications and timing of cholecystectomy, particularly for mild biliary pancreatitis, has gradually accumulated. Lastly, there are exciting possibilities for novel agents to treat or prevent cholesterol stone disease. This review covers new advances in our understanding of the natural history, clinical associations, and management of gallstone disease.

The changing faces of cholangitis

A variety of diseases are included under the umbrella term ‘cholangitis’, including hepatobiliary diseases with an autoimmune pathogenesis (such as primary sclerosing cholangitis, primary biliary cholangitis, and IgG4-associated sclerosing cholangitis) and disease processes associated with intraductal stones and infectious etiologies (such as ascending bacterial cholangitis, recurrent pyogenic cholangitis, and liver fluke-associated cholangitis). Recent advances in the pathophysiologic bases of these disorders, particularly with respect to the autoimmune variety, are allowing improved diagnosis and prognostication as well as providing the opportunity to refine and re-imagine treatment modalities. The aim of this review is to highlight selected advances in cholangitis research that point to novel insights into the pathophysiology, diagnosis, and treatment of this diverse array of disorders.

Role of protein kinase C-η in cigarette smoke extract-induced apoptosis in MRC-5-cells

Cigarette smoke (CS) is a major risk factor for emphysema, which causes cell death in structural cells of the lung by mechanisms that are still not completely understood. We demonstrated previously that CS extract (CSE) induces caspase activation in MRC-5 human lung fibroblasts, activated protein kinase C-η (PKC-η), and translocated PKC-η from the cytosol to the membrane. The objective of this study was to investigate the involvement of PKC-η activation in a CSE-induced extrinsic apoptotic pathway. We determined that CSE increases expression of caspase 3 and 8 cleavage in MRC-5 cells and overexpression of PKC-η significantly increased expression of caspase 3 and 8 cleavage compared with control LacZ-infected cells. In contrast, dominant negative (dn) PKC-η inhibited apoptosis in MRC-5 cells exposed to CSE and decreased expression of caspase 3 and 8 compared with control cells. Exposure to 10% CSE for >8 h significantly increased lactate dehydrogenase release in PKC-η-infected cells compared with LacZ-infected cells. Additionally, PKC-η-infected cells had an increased number of Hoechst 33342 stained nuclei compared with LacZ-infected cells, while dn PKC-η-infected cells exhibited fewer morphological changes than LacZ-infected cells under phase-contrast microscopy. In conclusion, PKC-η activation plays a pro-apoptotic role in CSE-induced extrinsic apoptotic pathway in MRC-5 cells. These results suggest that modulation of PKC-η may be a useful tool for regulating the extrinsic apoptosis of MRC-5 cells by CSE and may have therapeutic potential in the treatment of CS-induced lung injury.

Physical activity, maternal metabolic measures, and the incidence of gallbladder sludge or stones during pregnancy: a randomized trial

OBJECTIVE

To evaluate the effect of a physical activity intervention upon the incidence of gallbladder sludge or stones during pregnancy.

STUDY DESIGN

Pregnant women without gallstones were randomized to an intervention to increase moderate to vigorous physical activity or control. Intervention group women received motivational materials and small-group instruction to increase physical activity. Gallbladder ultrasound and blood draws were obtained at entry, 18 weeks' gestation, and 36 weeks' gestation.

RESULTS

In all, 591 were randomized to the intervention and 605 women to control groups. Women in the intervention group reported modestly higher levels of physical activity compared with control women, and fewer women in the intervention group reported no physical activity during pregnancy. The incidence of gallbladder sludge or stones was similar in intervention and control groups at 18 weeks (4.8% versus 5.4%; relative risk 0.89; 95% confidence interval 0.53, 1.47) and 36 weeks (4.3% versus 3.3%; relative risk 1.31; 95% confidence interval 0.70, 2.54). Fasting glucose, lipid, insulin, leptin, and adiponectin levels were similar in the two groups, as was insulin sensitivity and the incidence of gestational diabetes.

CONCLUSION

An intervention to increase moderate to vigorous physical activity did not decrease the incidence of gallbladder sludge or stones during pregnancy and did not result in improvement in maternal metabolic measures.

Cord blood T cells retain early differentiation phenotype suitable for immunotherapy after TCR gene transfer to confer EBV specificity

Adoptive T cell therapy can be effective for Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disease and melanoma. Transducing high-affinity TCR genes into T lymphocytes is an emerging method to improve potency and specificity of tumor-specific T cells. However, both methods necessitate in vitro lymphocyte proliferation, generating highly differentiated effector cells that display reduced survival and antitumor efficacy postinfusion. TCR-transduction of naive lymphocytes isolated from peripheral blood is reported to provide superior in vivo survival and function. We utilized cord blood (CB) lymphocytes, which comprise mainly naive cells, for transducing EBV-specific TCR. Comparable TCR expression was achieved in adult and CB cells, but the latter expressed an earlier differentiation profile. Further antigen-driven stimulation skewed adult lymphocytes to a late differentiation phenotype associated with immune exhaustion. In contrast, CB T cells retained a less differentiated phenotype after antigen stimulation, remaining CD57-negative but were still capable of antigen-specific polyfunctional cytokine expression and cytotoxicity in response to EBV antigen. CB T cells also retained longer telomeres and in general possessed higher telomerase activity indicative of greater proliferative potential. CB lymphocytes therefore have qualities indicating prolonged survival and effector function favorable to immunotherapy, especially in settings where donor lymphocytes are unavailable such as in solid organ and CB transplantation.

Liver fluke-induced hepatic oxysterols stimulate DNA damage and apoptosis in cultured human cholangiocytes

Oxysterols are cholesterol oxidation products that are generated by enzymatic reactions through cytochrome P450 family enzymes or by non-enzymatic reactions involving reactive oxygen and nitrogen species. Oxysterols have been identified in bile in the setting of chronic inflammation, suggesting that biliary epithelial cells are chronically exposed to these compounds in certain clinical settings. We hypothesized that biliary oxysterols resulting from liver fluke infection participate in cholangiocarcinogenesis. Using gas chromatography/mass spectrometry, we identified oxysterols in livers from hamsters infected with Opisthorchis viverrini that develop cholangiocarcinoma. Five oxysterols were found: 7-keto-cholesta-3,5-diene (7KD), 3-keto-cholest-4-ene (3K4), 3-keto-cholest-7-ene (3K7), 3-keto-cholesta-4,6-diene (3KD), and cholestan-3β,5α,6β-triol (Triol). Triol and 3K4 were found at significantly higher levels in the livers of hamsters with O. viverrini-induced cholangiocarcinoma. We therefore investigated the effects of Triol and 3K4 on induction of cholangiocarcinogenesis using an in vitro human cholangiocyte culture model. Triol- and 3K4-treated cells underwent apoptosis. Western blot analysis showed significantly increased levels of Bax and decreased levels of Bcl-2 in these cells. Increased cytochrome c release from mitochondria was found following treatment with Triol and 3K4. Triol and 3K4 also induced formation of the DNA adducts 1,N(6)-etheno-2'-deoxyadenosine, 3,N(4)-etheno-2'-deoxycytidine and 8-oxo-7,8-dihydro-2'-deoxyguanosine in cholangiocytes. The data suggest that Triol and 3K4 cause DNA damage via oxidative stress. Chronic liver fluke infection increases production of the oxysterols Triol and 3K4 in the setting of chronic inflammation in the biliary system. These oxysterols induce apoptosis and DNA damage in cholangiocytes. Insufficient and impaired DNA repair of such mutated cells may enhance clonal expansion and further drive the change in cellular phenotype from normal to malignant.

Hepatic free cholesterol accumulates in obese, diabetic mice and causes nonalcoholic steatohepatitis

BACKGROUND & AIMS

Type 2 diabetes and nonalcoholic steatohepatitis (NASH) are associated with insulin resistance and disordered cholesterol homeostasis. We investigated the basis for hepatic cholesterol accumulation with insulin resistance and its relevance to the pathogenesis of NASH.

METHODS

Alms1 mutant (foz/foz) and wild-type NOD.B10 mice were fed high-fat diets that contained varying percentages of cholesterol; hepatic lipid pools and pathways of cholesterol turnover were determined. Hepatocytes were exposed to insulin concentrations that circulate in diabetic foz/foz mice.

RESULTS

Hepatic cholesterol accumulation was attributed to up-regulation of low-density lipoprotein receptor via activation of sterol regulatory element binding protein 2 (SREBP-2), reduced biotransformation to bile acids, and suppression of canalicular pathways for cholesterol and bile acid excretion in bile. Exposing primary hepatocytes to concentrations of insulin that circulate in diabetic Alms1 mice replicated the increases in SREBP-2 and low-density lipoprotein receptor and suppression of bile salt export pump. Removing cholesterol from diet prevented hepatic accumulation of free cholesterol and NASH; increasing dietary cholesterol levels exacerbated hepatic accumulation of free cholesterol, hepatocyte injury or apoptosis, macrophage recruitment, and liver fibrosis.

CONCLUSIONS

In obese, diabetic mice, hyperinsulinemia alters nuclear transcriptional regulators of cholesterol homeostasis, leading to hepatic accumulation of free cholesterol; the resulting cytotoxicity mediates transition of steatosis to NASH.

Association between dietary nutrient composition and the incidence of cirrhosis or liver cancer in the United States population

Little is known about the impact of dietary factors on the progression of liver disease. Our aim was to determine whether dietary intake was associated with the risk of cirrhosis-related or liver cancer-related death or hospitalization in the U.S. population. Participants included 9221 persons aged 25-74 years without evidence of cirrhosis at entry into the study or during the first 5 years of follow-up, who were subsequently followed for a mean of 13.3 years as part of the first National Health and Nutrition Examination Survey. Dietary intake was ascertained at baseline using a 24-hour dietary recall questionnaire. During follow-up, 123 of 9221 participants had a diagnosis of cirrhosis (n = 118) or liver cancer (n = 5) in hospitalization records or death certificates, including 36 who were diagnosed only on the basis of death certificates. Participants who reported a diet high in protein were at a higher risk of hospitalization or death due to cirrhosis or liver cancer (P = 0.001), whereas those who reported a diet high in carbohydrates were at a lower risk (P = 0.003), after adjusting for potential confounders (daily consumption of protein, carbohydrate, fat, tea or coffee, and alcohol, gender, race, age, educational attainment, U.S. geographical region, diabetes, body mass index, and subscapular-to-triceps skinfold ratio). Although total fat consumption was not significantly associated with the risk of cirrhosis or liver cancer, cholesterol consumption was associated with higher risk (P = 0.007), whereas serum cholesterol level was not associated with risk of cirrhosis or liver cancer.

CONCLUSION

Diet may be an important and potentially modifiable determinant of liver disease.

Effects of lipopolysaccharide on platelet-derived growth factor isoform and receptor expression in cultured rat common bile duct fibroblasts and cholangiocytes

BACKGROUND AND AIM

Little is known about the role of platelet-derived growth factor (PDGF) in biliary fibrosis in the setting of bacterial colonization of the biliary tree. We therefore sought to investigate whether exposure to bacterial lipopolysaccharide (LPS) alters PDGF isoform and receptor expression in cultured rat common bile duct fibroblasts (CBDF) and normal rat cholangiocytes (NRC).

METHODS

Collagen content in cells and media was assessed by colorimetric assay and gel electrophoresis. mRNA levels of PDGF-A and -B, and PDGF-Receptors (PDGF-R) alpha and beta were measured by relative quantitative real-time PCR. Protein levels of PDGF-AA, AB and BB were measured by ELISA, and PDGF-Ralpha and PDGF-Rbeta by Western blot.

RESULTS

In CBDF, LPS increased total soluble collagen synthesis and secretion. PDGF-Ralpha and beta mRNA and protein were also increased by LPS treatment in CBDF. Lipopolysaccharide treatment elicited an increase in PDGF-A and -B mRNA levels in CBDF. In NRC, levels of PDGF-AmRNAincreased in a dose-dependent fashion following LPS treatment, whereas PDGF-B mRNA showed no response. PDGF-AA secretion was higher by CBDF than by NRC. PDGF-BB levels were also higher in CBDF than in NRC. While PDGF-BB levels did not respond to LPS treatment in CBDF, there was a dosedependent response of this isoform to LPS in NRC. Intracellular and secreted PDGF-AB increased with LPS treatment in NRC.

CONCLUSIONS

These results support a model in which chronic bacterial colonization of the biliary tree induces fibrosis through PDGF-dependent mechanisms.

Peripheral amyloid-beta levels regulate amyloid-beta clearance from the central nervous system

Amyloid-beta (Abeta) is cleared from the brain by both proteolytic digestion and transport across the blood-brain-barrier into the peripheral circulatory system. To investigate the role peripheral Abeta levels play in regulating Abeta brain clearance, we measured the clearance of [125I]-Abeta(1-40) injected into the brains of liver-ligated rats that allowed peripheral Abeta levels to be maintained at elevated levels for approximately one hour with/without a single peripheral bolus of unlabeled Abeta(1-40). We found that elevating peripheral Abetalevels significantly decreased [125I]-Abeta(1-40) brain clearance, thus supporting the hypothesis that peripheral Abeta levels regulate Abeta clearance from the central nervous system.

Gallbladder epithelial cells that engraft in mouse liver can differentiate into hepatocyte-like cells

We tested the hypothesis that well-differentiated gallbladder epithelial cells (GBECs) are capable of engrafting and surviving in murine liver and acquire phenotypic characteristics of hepatocytes. GBECs isolated from transgenic mice that constitutively express green fluorescent protein (GFP) were either cultured before transplantation or transplanted immediately following isolation. Recipient mice with severe-combined immunodeficiency underwent retrorsine treatment and either partial hepatectomy before transplantation or carbon tetrachloride treatment following transplantation. From 1 to 4 months following transplantation, the livers of recipient mice contained discrete colonies of GFP(+) cells. Most GFP(+) cells surrounded vesicles, were epithelial cell-like in morphology, and expressed the biliary epithelial markers cytokeratin 19 and carbonic anhydrase IV. Subpopulations of GFP(+) cells resembled hepatocytes morphologically and expressed the hepatocyte-specific markers connexin-32 and hepatic nuclear factor-4alpha, but not cytokeratin 19 or carbonic anhydrase IV. At 4 months, cells in GFP(+) colonies were not actively proliferating as determined by proliferating cell nuclear antigen expression. Thus, GBECs are capable of engrafting and surviving in damaged mouse livers, and some can differentiate into cells with hepatocyte-like features. These findings suggest that environmental cues in the recipient liver are sufficient to allow a subpopulation of donor GBECs to differentiate into hepatocyte-like cells in the absence of exogenous transcriptional reprogramming. GBECs might be used as donor cells in a cell transplantation approach for the treatment of liver disease.

Cornulin, a marker of late epidermal differentiation, is down-regulated in eczema

BACKGROUND

Eczema is a common chronic inflammatory skin disorder which shows strong genetic predisposition. To identify new potential molecular determinants of the disease pathogenesis, we performed a gene expression study in an eczema mouse model. This analysis identified a marked down regulation of the cornulin gene (CRNN), a member of the epidermal differentiation complex, in the eczema-like skin. We then investigated CRNN as an eczema candidate gene and studied its polymorphism and the expression in the skin of eczema patients.

METHODS

An eczema-like phenotype was induced in mice by allergen (Der p2) patching. Gene expression analysis was performed with the subtractive suppression hybridization method and validated by real time PCR and the transmission disequilibrium test was used to test for genetic associations in 406 multiplex eczema families.

RESULTS

Der p 2 patched mice developed a localized eczema and a Th 2 skewed systemic response. Real time PCR analysis confirmed a down regulation of CRNN mRNA in eczema-like skin in the mouse model and in human eczema. The CRNN polymorphism rs941934 was significantly associated with atopic eczema in the genetic analysis (P = 0.006), though only as part of an extended haplotype including a known associated variant (2282del4) in the filaggrin gene.

CONCLUSIONS

CRNN mRNA expression is decreased in eczematous skin. Further studies are needed to verify whether the associated cornulin polymorphism contribute to the genetic susceptibility in eczema.

Serotonin metabolism is dysregulated in cholangiocarcinoma, which has implications for tumor growth

Cholangiocarcinoma is a devastating cancer of biliary origin with limited treatment options. Symptoms are usually evident after blockage of the bile duct by the tumor, and at this late stage, they are relatively resistant to chemotherapy and radiation therapy. Therefore, it is imperative that alternative treatment options are explored. We present novel data indicating that the metabolism of serotonin is dysregulated in cholangiocarcinoma cell lines, compared with normal cholangiocytes, and tissue and bile from cholangiocarcinoma patients. Specifically, there was an increased expression of tryptophan hydroxylase 1 and a suppression of monoamine oxidase A expression (enzymes responsible for the synthesis and degradation of serotonin, respectively) in cholangiocarcinoma. This resulted in an increased secretion of serotonin from cholangiocarcinoma and increased serotonin in the bile from cholangiocarcinoma patients. Increased local serotonin release may have implications on cholangiocarcinoma cell growth. Serotonin administration increased cholangiocarcinoma cell growth in vitro, whereas inhibition of serotonin synthesis decreases tumor cell growth both in vitro and in vivo. The data presented here represent the first evidence that serotonin metabolism is dysregulated in cholangiocarcinoma and that modulation of serotonin synthesis may represent an alternative target for the development of therapeutic strategies.

Physical chemistry of intestinal absorption of biliary cholesterol in mice

Although many putative sterol transporters influencing cholesterol absorption and physical-chemical factors affecting dietary cholesterol absorption have been extensively investigated, it is still unclear how biliary cholesterol contributes to the regulation of intestinal cholesterol absorption. We studied whether the gallbladder can modulate the microaggregates of cholesterol carriers, which may in turn influence the intestinal absorption of biliary cholesterol. Supersaturated, crystallized, or micellar model biles were delivered via a duodenal catheter to conscious, freely moving C57L mice daily for 2 days. Intestinal uptake and absorption of biliary cholesterol and its fecal excretion, as well as expression levels of intestinal sterol transporters, were analyzed. Cholesterol uptake and absorption by the enterocyte were dramatically reduced in mice treated with crystallized biles compared with supersaturated biles. This correlated with the higher cumulative radioactivity of cholesterol recovered in the feces at 24 hours. Such findings were absent with the added reference compound sitostanol. After removing cholesterol crystals from crystallized biles, micellar biles showed essentially identical effects on intestinal absorption but with lower fecal cholesterol excretion compared with the original samples containing crystals. Expression levels of the jejunal Abcg5 (ATP-binding cassette transporter G5) and Abcg8, but not Npc1l1 (Niemann-Pick C1 like 1), were significantly increased by supersaturated biles compared with crystallized biles.

CONCLUSION

Different physical forms of biliary cholesterol dramatically determine intestinal uptake and absorption of cholesterol. Solid plate-like cholesterol monohydrate crystals in bile are probably not absorbed and are totally excreted in feces from the body. The gallbladder may have a role in regulating cholesterol homeostasis by modulating the physical forms of biliary cholesterol.

Thymol and related alkyl phenols activate the hTRPA1 channel

BACKGROUND AND PURPOSE

Thymol, a major component of thyme and oregano, has medical uses in oral care products as an astringent and antibiotic. Its distinctive sharp odour and pungent flavour are considered aversive properties. The molecular basis of these aversive properties is not well understood.

EXPERIMENTAL APPROACH

The ability of thymol to activate human transient receptor potential channel A1 (hTRPA1) expressed in stably transfected human embryonic kidney 293 (HEK293) cells was measured by membrane potential and calcium-sensitive dyes in a fluorescence-imaging plate reader (FLIPR) assay. Direct activation of hTRPA1 currents was measured by whole-cell voltage clamp recording. Intracellular calcium changes were measured using fura-2 dye. The FLIPR assay was also used to measure membrane potential changes elicited by thymol after pretreatment with camphor, a known TRPA1 inhibitor. The ability of related alkyl phenols to activate hTRPA1 was also determined.

KEY RESULTS

Thymol potently activated a membrane potential response and intracellular calcium increase in hTRPA1-expressing HEK293 cells in a concentration-dependent manner. Activation by thymol desensitized hTRPA1 to further exposure to thymol or the known ligand allyl isothiocyanate (AITC). The related phenols 2-tert-butyl-5-methylphenol, 2,6-diisopropylphenol (propofol) and carvacrol also activated hTRPA1. Phenols with less bulky carbon substitutions and lower logP values were less potent in general. The response to thymol was blocked by camphor.

CONCLUSIONS AND IMPLICATIONS

These results suggest a role for hTRPA1 activation in the reported pungent and aversive properties of some of these pharmaceutically important phenols.

Insulin resistance and incident gallbladder disease in pregnancy

BACKGROUND & AIMS

Insulin resistance is associated with prevalent gallstones, but its effect on initial gallstone formation is not well-understood.

METHODS

We conducted a nested case-control study to examine whether insulin resistance is a risk factor for initial gallbladder sludge and stone formation during pregnancy. Cases were 205 women with new gallbladder sludge and stones during pregnancy and the early postpartum. Controls were 443 randomly selected women without sludge or stones during pregnancy. Gallbladder ultrasounds were obtained during each trimester and at 4-6 weeks post partum. Fasting serum glucose, lipids, and insulin were measured at 26-28 weeks gestation. Insulin resistance was measured by the homeostasis model. Logistic regression was used to identify independent risk factors for gallstone formation.

RESULTS

Insulin resistance was significantly greater in cases than in controls on univariate analysis (P < .001). Pre-pregnancy body mass index was strongly associated with gallstone formation on univariate analysis (P < .001), but this association was diminished after adjusting for insulin resistance (P = .01). On multivariate analysis, insulin resistance was significantly associated with gallstone formation (P = .004), even after adjustment for pre-pregnancy body mass index and other confounding factors including high-density lipoprotein cholesterol and physical activity. This association was strongest in women with pre-pregnancy body mass index <30 kg/m(2).

CONCLUSIONS

Insulin resistance is a risk factor for incident gallbladder sludge and stones during pregnancy, even after adjustment for body mass index. Insulin resistance might represent a causal link between obesity and overweight and gallstones.

Murine gallbladder epithelial cells can differentiate into hepatocyte-like cells in vitro

We determined whether extrahepatic biliary epithelial cells can differentiate into cells with phenotypic features of hepatocytes. Gallbladders were removed from transgenic mice expressing hepatocyte-specific beta-galactosidase (beta-Gal) and cultured under standard conditions and under experimental conditions designed to induce differentiation into a hepatocyte-like phenotype. Gallbladder epithelial cells (GBEC) cultured under standard conditions exhibited no beta-Gal activity. beta-Gal expression was prominent in 50% of cells cultured under experimental conditions. Similar morphological changes were observed in GBEC from green fluorescent protein transgenic mice cultured under experimental conditions. These cells showed higher levels of mRNA for genes expressed in hepatocytes, but not in GBEC, including aldolase B, albumin, hepatocyte nuclear factor-4alpha, aldehyde dehydrogenase 1, and glutamine synthetase, and they synthesized bile acids. Additional functional evidence of a hepatocyte-like phenotype included LDL uptake and enhanced benzodiazepine metabolism. Connexin-32 expression was evident in murine hepatocytes and in cells cultured under experimental conditions, but not in cells cultured under standard conditions. Notch 1, 2, and 3 and Notch ligand Jagged 1 mRNAs were downregulated in these cells compared with cells cultured under standard conditions. CD34, alpha-fetoprotein, and Sca-1 mRNA were not expressed in cells cultured under standard conditions, suggesting that the hepatocyte-like cells did not arise from hematopoietic stem cells or oval cells. These results point to future avenues for investigation into the potential use of GBEC in the treatment of liver disease.

Incidence and predictors of hepatocellular carcinoma in patients with cirrhosis

BACKGROUND & AIMS

Independent predictors of hepatocellular carcinoma in patients with cirrhosis are not well established.

METHODS

We created a cohort of 2126 patients (41% with hepatitis C virus [HCV] infection) who sought care from all Veterans Affairs health care centers in the northwest United States from 1994 to 2005 and who had a diagnosis of cirrhosis recorded in inpatient or outpatient medical records.

RESULTS

During a mean follow-up period of 3.6 years, 100 patients were diagnosed with hepatocellular carcinoma (incidence, 1.3 per 100 patient-years). Important predictors of hepatocellular carcinoma in multivariate models included HCV infection (adjusted hazard ratio [ahr], 3.0; 95% confidence interval [CI], 1.7-5.3); hepatitis B virus (HBV) surface antigen (ahr, 3.3; 95% CI, 1.4-7.7); HBV core antibody (ahr, 1.7; 95% CI, 1.1-2.8); obesity (ahr, 2.5; 95% CI, 1.3-4.9), and overweight (ahr, 2.8; 95% CI, 1.5-5.4) relative to patients with a body mass index of < 25 kg/m2, diabetes (ahr, 1.5; 95% CI, 0.9-2.5), and low platelet count (relative to patients with a platelet count of > 266 thousands/microL, the ahr was 2.1 [95% CI, 0.8-5.6] in patients with a platelet count of 180-266 thousands/microL, 3.3 [95% CI, 1.3-8.0] in patients with a platelet count of 111-179 thousands/microL, and the ahr was 4.7 [95% CI, 2.0-11.4] in patients with a platelet count of < or = 110 thousands/microL).

CONCLUSIONS

We identified 6 important predictors of hepatocellular carcinoma in multivariate models (including relatively novel predictors such as increased body mass index, HBV core antibody, and low platelet count), which suggest a means of predicting the risk of hepatocellular carcinoma in patients with cirrhosis and optimizing surveillance strategies.

Paclitaxel interrupts TGF-beta1 signaling between gallbladder epithelial cells and myofibroblasts

BACKGROUND

The cellular and molecular mechanisms of fibrogenesis in the extrahepatic biliary epithelium are not known. Transforming growth factor-beta1 (TGF-beta1) is a cytokine implicated in signaling pathways that mediate collagen formation. An observation that paclitaxel (PT), applied topically into the rat common bile duct, inhibited stricture formation led us to hypothesize that PT's effects might be due to interruption of TGF-beta1 signaling between biliary epithelial cells and subepithelial myofibroblasts.

MATERIALS AND METHODS

We tested this hypothesis using an in vitro cell-culture model in which murine gallbladder epithelial cells (GBEC) are cultured separately or cocultured with human gallbladder myofibroblasts (GBMF).

RESULTS

Exposure to Escherichia coli lipopolysaccharide (LPS) enhanced TGF-beta1 mRNA expression and stimulated TGF-beta1 protein secretion into both apical and basolateral compartments in GBEC. This effect was more prominent with basolateral secretion and was also more pronounced in the coculture system. In GBMF, collagen I mRNA expression and protein secretion were stimulated by treatment with LPS or TGF-beta1. GBMF also expressed TGF-beta1 mRNA, whose levels were enhanced by exposure to either LPS or exogenous TGF-beta1. PT inhibited LPS-induced TGF-beta1 mRNA expression and protein secretion in GBEC in both culture systems. Tumor necrosis factor-alpha mRNA expression and protein secretion were not affected by PT in GBEC, demonstrating that the effects were specific for TGF-beta1. PT also inhibited LPS- and TGF-beta1-induced collagen I mRNA expression and protein secretion in GBMF.

CONCLUSIONS

These findings support a model in which GBEC communicate with subepithelial GBMF via TGF-beta1, leading to collagen deposition and fibrosis, and in which GBMF possess autocrine mechanisms involving TGF-beta1 that could regulate collagen production. PT inhibits these fibrogenic pathways.

Quantitative MRI reveals aging-associated T2 changes in mouse models of Alzheimer's disease

In this study, we used MRI to analyze quantitative parametric maps of transverse (T(2)) relaxation times in a longitudinal study of transgenic mice expressing mutant forms of amyloid precursor protein (APP), presenilin (PS1), or both (PS/APP), modeling aspects of Alzheimer's disease (AD). The main goal was to characterize the effects of progressive beta-amyloid accumulation and deposition on the biophysical environment of water and to investigate if these measurements would provide early indirect evidence of AD pathological changes in the brains of these mice. Our results demonstrate that at an early age before beta-amyloid deposition, only PS/APP mice show a reduced T(2) in the hippocampus and cortex compared with wild-type non-transgenic (NTg) controls, whereas a statistically significant within-group aging-associated decrease in T(2) values is seen in the cortex and hippocampus of all three transgenic genotypes (APP, PS/APP, and PS) but not in the NTg controls. In addition, for animals older than 12 months, we confirmed our previous report that only the two genotypes that form amyloid plaques (APP and PS/APP) have significantly reduced T(2) values compared with NTg controls. Thus, T(2) changes in these AD models can precede amyloid deposition or even occur in AD models that do not deposit beta-amyloid (PS mice), but are intensified in the presence of amyloid deposition.

Gene expression patterns in pancreatic tumors, cells and tissues

Background

Cancers of the pancreas originate from both the endocrine and exocrine elements of the organ, and represent a major cause of cancer-related death. This study provides a comprehensive assessment of gene expression for pancreatic tumors, the normal pancreas, and nonneoplastic pancreatic disease.

Methods/Results

DNA microarrays were used to assess the gene expression for surgically derived pancreatic adenocarcinomas, islet cell tumors, and mesenchymal tumors. The addition of normal pancreata, isolated islets, isolated pancreatic ducts, and pancreatic adenocarcinoma cell lines enhanced subsequent analysis by increasing the diversity in gene expression profiles obtained. Exocrine, endocrine, and mesenchymal tumors displayed unique gene expression profiles. Similarities in gene expression support the pancreatic duct as the origin of adenocarcinomas. In addition, genes highly expressed in other cancers and associated with specific signal transduction pathways were also found in pancreatic tumors.

Conclusion

The scope of the present work was enhanced by the inclusion of publicly available datasets that encompass a wide spectrum of human tissues and enabled the identification of candidate genes that may serve diagnostic and therapeutic goals.

PPARG locus haplotype variation and exacerbations in asthma

The peroxisome proliferator-activated receptor gamma (PPARgamma) regulates inflammation and may play a role in asthma. Using mouthwash-derived DNA and clinical interviews and measurements, we investigated the association of previously characterized single-nucleotide polymorphisms in the PPARG gene (Pro12Ala, C1431T, and C-681G) with asthma exacerbations in patients aged 3-22 years (n=569). The common homozygous haplotype combination of the Pro12 and C1431 alleles was associated with increased risk for asthma exacerbations (ProC, odds ratio (OR) 1.87, 95% confidence interval 1.25-2.79; P=0.002). The ProC genotype was associated with increased school absences (OR 1.82, 95% confidence interval 1.21-2.76; P=0.004) and hospital admissions (OR 2.32, 95% confidence interval 1.18-4.58; P=0.015) over the preceding 6 months. The population-attributable risk of this genotype was 33%. Common genetic variation at the PPARG locus may play an important role in modulating the long-term control of asthma in children and young adults.

Gastric fluid bile concentrations and risk of Barrett's esophagus

Patients with Barrett's esophagus are at high risk of progression to adenocarcinoma. A growing, but conflicting body of evidence implicates bile reflux as a contributor to Barrett's esophagus. To investigate whether duodenogastric reflux was associated with an increased risk of Barrett's esophagus, a case-control study of incident Barrett's esophagus was performed. Cases (n=72) were identified by new histologically-confirmed diagnosis of specialized intestinal metaplasia (indicative of Barrett's esophagus) following upper endoscopy for refractory gastroesophageal reflux between October 1997 and September 2000. Cases were compared to gastroesophageal reflux patients without specialized intestinal metaplasia (controls; n=72). There was no difference in total bile acid concentrations between cases and controls. Risk of Barrett's esophagus did not significantly vary with increasing concentrations of total or free bile acids, respectively (OR 0.35 (95% CI 0.12, 1.02) and 0.60 (95% CI 0.22, 1.66)). Low gastric fluid pH (toxic range 3-5), was associated with a non-significant increase in the risk of Barrett's esophagus. In conclusion, no significant association between Barrett's esophagus and total or free bile acids in gastric refluxate was found. Patients with low gastric fluid pH (3-5) may represent a subset of patients at high risk of developing Barrett's esophagus.

Increase in circulating Foxp3+CD4+CD25(high) regulatory T cells in nasopharyngeal carcinoma patients

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus-associated disease with high prevalence in Southern Chinese. Using multiparametric flow cytometry, we identified significant expansions of circulating naïve and memory CD4+CD25(high) T cells in 56 NPC patients compared with healthy age- and sex-matched controls. These were regulatory T cells (Treg), as they overexpressed Foxp3 and GITR, and demonstrated enhanced suppressive activities against autologous CD4+CD25- T-cell proliferation in functional studies on five patients. Abundant intraepithelial infiltrations of Treg with very high levels of Foxp3 expression and absence of CCR7 expression were also detected in five primary tumours. Our current study is the first to demonstrate an expansion of functional Treg in the circulation of NPC patients and the presence of infiltrating Treg in the tumour microenvironment. As Treg may play an important role in suppressing antitumour immunity, our findings provide critical insights for clinical management of NPC.

Absence of CFTR is associated with pleiotropic effects on mucins in mouse gallbladder epithelial cells

Mucus of cystic fibrosis patients exhibits altered biochemical composition and biophysical behavior, but the causal relationships between altered cystic fibrosis transmembrane conductance regulator (CFTR) function and the abnormal mucus seen in various organ systems remain unclear. We used cultured gallbladder epithelial cells (GBEC) from wild-type and Cftr((-/-)) mice to investigate mucin gene and protein expression, kinetics of postexocytotic mucous granule content expansion, and biochemical and ionic compositions of secreted mucins. Muc1, Muc3, Muc4, Muc5ac, and Muc5b mRNA levels were significantly lower in Cftr((-/-)) GBEC compared with wild-type cells, whereas Muc2 mRNA levels were higher in Cftr((-/-)) cells. Quantitative immunoblotting demonstrated a trend toward lower MUC1, MUC2, MUC3, MUC5AC, and MUC5B mucin levels in Cftr((-/-)) cells compared with cells from wild-type mice. In contrast, the levels of secreted MUC1, MUC3, MUC5B, and MUC6 mucins were significantly higher from Cftr((-/-)) cells; a trend toward higher levels of secreted MUC2 and MUC5AC was also noted from Cftr((-/-)) cells. Cftr((-/-)) cells demonstrated slower postexocytotic mucous granule content expansion. Calcium concentration was significantly elevated in the mucous gel secreted by Cftr((-/-)) cells compared with wild-type cells. Secreted mucins from Cftr((-/-)) cells contained higher sulfate concentrations. Thus absence of CFTR is associated with pleiotropic effects on mucins in murine GBEC.

Stereotactic Radiotherapy for the Treatment of Pituitary Adenomas

PURPOSE

The aim of this study was to retrospectively review local control and morbidity following stereotactic radiotherapy (SRT) for pituitary adenoma.

METHODS

Between 1997 and 2004, 39 patients with pituitary adenomas received SRT. Median age was 56 years (range: 13 to 90 years). Thirty-three patients underwent incomplete transsphenoidal surgery prior to SRT and six had unresectable tumors. The largest tumor dimension varied from 1.7 to 6 cm (median: 3 cm). Tumor volume varied from 1.2 to 56 mL (median 10.5 mL). Thirty-five tumors were < or = 1 mm from the optic chiasm/nerve. Thirty-three tumors were non-functional. SRT was delivered by a dedicated linear accelerator (Novalis, Heimstetten, Germany). Beam collimation was achieved by a fixed circular collimator (five patients) or a micro-multileaf collimator (34 patients). Total dose varied from 4500 to 5040 cGy (median: 4860 cGy) and was prescribed at the 90 % isodose line.

RESULTS

After a median follow-up of 32 months (range: 12 to 94 months), the local control rate was 100 %. Tumor size was stable in 26 patients and decreased in 13 patients. Hormone normalization did not occur following SRT. New endocrine deficiency occurred in six patients. No patient developed cranial nerve injury or second malignancy following treatment.

CONCLUSIONS

SRT achieves a high rate of local control and a low rate of treatment-induced morbidity. SRT is applicable to pituitary adenomas in close proximity to the optic apparatus and tumors in excess of three centimeters in the greatest dimension. Further follow-up is necessary to establish the long-term outcome following SRT for pituitary adenomas.

Elevated serum alanine aminotransferase activity and calculated risk of coronary heart disease in the United States

In the United States, elevated serum alanine aminotransferase (ALT) activity in the absence of viral hepatitis or excessive alcohol consumption is most commonly attributed to nonalcoholic fatty liver disease (NAFLD). NAFLD is related to predictors of coronary heart disease (CHD) such as insulin resistance and central obesity. We examined the association between elevated serum ALT activity and the 10-year risk of CHD as estimated using the Framingham risk score (FRS). We performed a cross-sectional analysis comparing participants in the Third National Health and Nutrition Examination Survey with normal and elevated ALT activity (>43 IU/L), examining the mean levels of FRS. Among participants without viral hepatitis or excessive alcohol consumption, those with elevated ALT activity (n=267) had a higher FRS than those with normal ALT activity (n=7259), both among men (mean difference in FRS 0.25, 95% CI 0.07-0.4; hazard ratio for CHD 1.28, 95% CI 1.07-1.5) and women (mean difference in FRS 0.76, 95% CI 0.4-1.1; hazard ratio for CHD 2.14, 95% CI 1.5-3.0). The ALT threshold for increased risk of CHD was higher in men (>43 IU/L) than in women (>30 IU/L). Elevated ALT activity was not associated with higher FRS among nonobese participants with viral hepatitis or excessive alcohol consumption. In condusion, individuals with elevated serum ALT activity in the absence of viral hepatitis or excessive alcohol consumption, most of whom have NAFLD, have an increased calculated risk of CHD. This association is more prominent in women.

The production of oxysterols in bile by activated human leukocytes

Oxysterols are naturally occurring intermediates in the conversion of cholesterol to bile acids, the major route for elimination of cholesterol. Additionally, they are important signaling agents, particularly in control of cholesterol synthesis; however, some species also are cytotoxic and carcinogenic. Oxysterols in plasma, contained in oxidized low-density lipoprotein, are strongly correlated with atherosclerosis. Oxysterols are found in infected human bile and the oxysterol content in gallstones correlates with bacterial DNA in the stones. Here we demonstrate that human leukocytes, activated by the presence of bacterial lipopolysaccharide, are able to oxidize cholesterol to a variety of oxysterols, including species known to be carcinogenic.

The prevalence and predictors of elevated serum aminotransferase activity in the United States in 1999-2002

OBJECTIVES

The presence of elevated serum aminotransferase activity is a sign of possible underlying liver disease. We aimed to describe the prevalence and associations of elevated serum aminotransferase activity in a recent, nationally representative U.S. survey.

METHODS

We described the prevalence and predictors of elevated alanine aminotransferase (ALT >43 IU/L) or elevated aspartate aminotransferase (AST >40 IU/L) activity among 6,823 participants of the National Health and Nutrition Examination Survey (NHANES) conducted between 1999 and 2002. We compared our findings to the results already published based on the NHANES conducted between 1988 and 1994.

RESULTS

In NHANES 1999-2002, the prevalences of elevated ALT, AST, or either ALT or AST were 8.9%, 4.9%, and 9.8%, respectively, in the entire population and 7.3%, 3.6%, and 8.1%, respectively, after excluding participants who tested positive for hepatitis C virus (HCV) antibody or reported excessive alcohol consumption. Strong predictors of elevated ALT activity included increasing waist circumference and body mass index, alcohol consumption, male sex, Mexican American ethnicity, decreasing age, and presence of HCV antibody. In NHANES 1988-1994, which employed a different assay methodology, the prevalences of elevated aminotransferases were approximately half of the prevalences we describe in NHANES 1999-2002, but the predictors of elevated ALT activity were similar.

CONCLUSIONS

The current prevalence of elevated ALT activity in the United States (8.9%) is more than double that of previously available estimates. This prevalence is very high (7.3%) even among persons without viral hepatitis C or excessive alcohol consumption and is strongly associated with risk factors for nonalcoholic fatty liver disease.

Interactions between sphingomyelin and cholesterol in low density lipoproteins and model membranes

This work examines three related, but previously unexplored, aspects of membrane biophysics and colloid science in the context of atherosclerosis. First, we show that sphingomyelinase (SMase)-induced aggregation of low density lipoproteins (LDLs), coupled with LDL exposure to cholesterol esterase (CEase), results in nucleation of cholesterol crystals, long considered the hallmark of atherosclerosis. In particular, this study reveals that the order of enzyme addition does not effect the propensity of LDL to nucleate cholesterol crystals, raising the possibility that nucleation can proceed from either the intra- or extracellular space. Second, we demonstrate that ceramide-rich aggregates of LDL release cholesterol to neighboring vesicles far more rapidly, and to a greater extent, than does native LDL. A likely explanation for this observation is displacement of cholesterol from SM-Chol rafts by "raft-loving" ceramide. Third, we demonstrate that a time-independent Förster resonance energy transfer (FRET) assay, based on dehydroergosterol and dansylated lecithin and used previously to study cholesterol nanodomains, can be used to measure raft sizes (on the order of 10 nm) in model membrane systems. Taken together, these observations point to the possibility of an extracellular nucleation mechanism and underscore the important role that biological colloids play in human disease.

Combined interaction of phospholipase C and apolipoprotein A-I with small unilamellar lecithin-cholesterol vesicles: influence of apolipoprotein A-I concentration and vesicle composition

We report the combined effects of phospholipase C (PLC), a pronucleating factor, and apolipoprotein A-I (apo A-I), an antinucleating factor, in solutions of model bile. Results indicate that apo A-I inhibits cholesterol nucleation from unilamellar lecithin vesicles by two mechanisms. Initially, inhibition is achieved by apo A-I shielding of hydrophobic diacylglycerol (DAG) moieties so as to prevent vesicle aggregation. Protection via shielding is temporary. It is lost when the DAG/apo A-I molar ratio exceeds a critical value. Subsequently, apo A-I forms small ( approximately 5-15 nm) complexes with lecithin and cholesterol that coexist with lipid-stabilized (400-800 nm) DAG oil droplets. This microstructural transition from vesicles to complexes avoids nucleation of cholesterol crystals and is a newly discovered mechanism by which apo A-I serves as an antinucleating agent in bile. The critical value at which a microstructural transition occurs depends on binding of apo A-I and so varies with the cholesterol mole fraction of vesicles. Aggregation of small, unilamellar, egg lecithin vesicles (SUVs) with varying cholesterol composition (0-60 mol %) was monitored for a range of apo A-I concentrations (2 to 89 microg/mL). Suppression of aggregation persists so long as the DAG-to-bound-apo A-I molar ratio is less than 100. A fluorescence assay involving dansylated lecithin shows that the suppression is an indirect effect of apo A-I rather than a direct inhibition of PLC enzyme activity. The DAG-to-total apo A-I molar ratio at which suppression is lost increases with cholesterol because of differences in apo A-I binding. Above this value, a microstructural transition to DAG droplets and lecithin/cholesterol A-I complexes occurs, as evidenced by sudden increases in turbidity and size and enhancement of Forster resonance energy transfer; structures are confirmed by cryo TEM.

Biliary sludge is formed by modification of hepatic bile by the gallbladder mucosa

BACKGROUND & AIMS

We studied 22 patients with symptomatic microlithiasis to determine whether a contributory role of the gallbladder in the early stage of cholesterol gallstone formation exists. We compared the merits of different methods (ultrasonography and microscopy) and sources (hepatic or gallbladder) of bile samples for diagnosing microlithiasis.

METHODS

Paired hepatic and gallbladder bile samples were studied with polarizing microscopy. Nucleation time, bile salts, phospholipid, cholesterol, cholesterol saturation index (CSI), bilirubin, total protein, albumin and mucin concentration were measured. All patients had abdominal ultrasound examination.

RESULTS

With polarizing microscopy as the standard, ultrasonography was positive in 13 patients (59%) and negative in 9 (41%). All gallbladder bile samples were positive for microlithiasis by microscopy. Only one hepatic bile sample was positive (P < .0001). There was a disproportional enrichment of total protein, albumin, and mucin (P < .05) in the gallbladder bile and a conversion of bilirubin diglucuronide to monoglucuronide (P < .01). Gallbladder samples had lower CSI but a faster nucleation time (P < .001), which correlates inversely with CSI, total protein, and mucin concentration.

CONCLUSION

Biochemical composition and physical chemical behavior of hepatic bile are modified during residence in the gallbladder, contributing to sludge formation. Gallbladder bile has a lower calculated CSI, higher deconjugation of bilirubin, protein and mucin concentration and crystals were present. Hepatic bile samples are inappropriate for microscopic detection of microlithiasis.

Effect of atenolol on QTc interval lengthening during hypoglycaemia in type 1 diabetes

AIMS/HYPOTHESIS

Hypoglycaemia is associated with heart rate-corrected QT (QTc) interval lengthening on the ECG; this may be important in the pathogenesis of sudden overnight death in young people with diabetes. Since hypoglycaemic QTc lengthening appears to be mediated through the sympathoadrenal response, we tested the hypothesis that beta1-blockade will prevent these changes in type 1 diabetic patients and so provide a potential therapeutic intervention.

METHODS

We studied eight type 1 diabetic adults without cardiovascular or renal complications. Similar hypoglycaemic clamp studies were performed on two occasions, at least 4 weeks apart, but immediately before one visit subjects received atenolol 100 mg daily for 7 days. Following a 60-min euglycaemic (5 mmol/l) period, blood glucose was lowered over 30 min to 2.5 mmol/l, and held for 60 min. High-resolution ECG was recorded at baseline and at 0, 30 and 60 min during each glycaemic plateau. QT interval was measured using a semiautomated tangent method and QTc was derived from QT using the Fridericia formula.

RESULTS

Mean (SD) baseline QTc was similar at both visits: control 391 (30) ms, post-atenolol 386 (34) ms; (p=0.33). Without atenolol pretreatment, QTc lengthened during hypoglycaemia to a maximum of 448 (34) ms (p<0.001). On atenolol, QTc lengthening was significantly reduced (peak QTc 413 (27) ms; p=0.004 vs control visit).

CONCLUSIONS/INTERPRETATION

Hypoglycaemic QTc lengthening is blunted by atenolol in patients with type 1 diabetes. Selective beta1-blockade may help prevent sudden death, if we can identify those at high risk.