Publications

Inflammatory bowel disease (IBD) is a devastating disease that is associated with excessive inflammation in the intestinal tract in genetically susceptible individuals and potentially triggered by microbial dysbiosis. This illness markedly predisposes patients to thrombophilia and chronic debility as well as bowel, lymphatic, and liver cancers. Development of new therapies is needed to re-establish long-term immune tolerance in IBD patients without increasing the risk of opportunistic infections and cancer. Aberrant purinergic signaling pathways have been implicated in disordered thromboregulation and immune dysregulation, as noted in the pathogenesis of IBD and other gastrointestinal/hepatic autoimmune diseases. Expression of CD39 on endothelial or immune cells allows for homeostatic integration of hemostasis and immunity, which are disrupted in IBD. Our focus in this review is on novel aspects of the functions of CD39 and related NTPDases in IBD. Regulated CD39 activity allows for scavenging of extracellular nucleotides, the maintenance of P2-receptor integrity and coordination of adenosinergic signaling responses. CD39 together with CD73, serves as an integral component of the immunosuppressive machinery of dendritic cells, myeloid cells, T and B cells. Genetic inheritance and environental factors closely regulate the levels of expression and phosphohydrolytic activity of CD39, both on immune cells and released microparticles. Purinergic mechanisms associated with T regulatory and supressor T helper type 17 cells modulate disease activity in IBD, as can be modeled in experimental colitis. As a recent example, upregulation of CD39 is dependent upon ligation of the aryl hydrocarbon receptor (AHR), as with natural ligands such as bilirubin and 2-(1' H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). Decreased expression of CD39 and/or dysfunctional AHR signaling, however, abrogates the protective effects of immunosuppressive AHR ligands. These factors could also serve as biomarkers of disease activity in IBD. Heightened thrombosis, inflammation, and immune disturbances as seen in IBD appear to be associated with aberrant purinergic signaling. Ongoing development of therapeutic strategies augmenting CD39 ectonucleotidase bioactivity via cytokines or AHR ligands offers promise for management of thrombophilia, disordered inflammation, and aberrant immune reactivity in IBD.

GOALS: To determine the association between functional disability and mortality after transjugular intrahepatic portosystemic shunt (TIPS).

BACKGROUND: TIPS is a common therapeutic procedure for cirrhotic patients with refractory ascites. The conventional metric for periprocedure risk stratification is the model for end-stage liver disease (MELD), which uses biochemical parameters to predict post-TIPS mortality. It does not account for functional disability.

STUDY: This is a retrospective cohort study of 83 patients admitted at an academic liver transplant center with cirrhosis and refractory ascites for the purpose of TIPS placement. We assessed the association of patients' reported activities of daily living (ADL) on a scale of 1 to 21 before TIPS with a primary outcome of 1-year mortality. Multivariable regression to adjust for MELD and Child class was performed.

RESULTS: A higher ADL score or functional independence, was associated with decreased 1-year mortality when modeled as both a continuous variable [odds ratio (OR), 0.80; 95% confidence interval (CI), 0.66-0.97; P=0.02) and a dichotomous variable (ADL 21 vs. <21; OR, 0.21; 95% CI, 0.05-0.70; P=0.01). After adjusting for MELD and Child class, functional independence was associated with decreased 1-year transplant-free mortality (OR, 0.22; 95% CI, 0.05-0.77; P=0.02). An ADL score consistent with dependence (<21) was significantly associated with a 3.40-day (95% CI, 1.76-5.04) longer hospital stay, adjusting for MELD and Child class (P<0.0001).

CONCLUSIONS: Functional disability is a predictor of post-TIPS mortality and length of stay after controlling for MELD.

BACKGROUND: Recent animal studies have shown that platelets directly activate hepatic stellate cells to promote liver fibrosis, whereas anti-platelet agents decrease liver fibrosis. It is unknown whether platelet inhibition by aspirin prevents liver fibrosis in humans.

AIM: To examine the association between aspirin use and liver fibrosis among adults with suspected chronic liver disease.

METHODS: We conducted a cross-sectional analysis using data from the National Health and Nutrition Examination Survey III. We identified 1856 individuals with suspected chronic liver disease (CLD). The degree of liver fibrosis was determined using four validated fibrosis indices and a composite index.

RESULTS: The use of aspirin was associated with a significantly lower composite liver fibrosis index calculated from FIB4, APRI, Forns and NFS [0.24 standard deviation (s.d.) units lower; 95% CI -0.42 to -0.06, P = 0.009]. The association of aspirin with lower fibrosis scores was significantly larger among those with suspected CLD compared to those without (-0.23 vs. -0.03 s.d. units; P interaction = 0.05). The negative association between aspirin use and lower fibrosis index was consistent across all four fibrosis indices (P = 0.002-0.08) in individuals with chronic viral hepatitis, suspected alcoholic liver disease and NASH. In comparison, no negative associations with liver fibrosis were seen with ibuprofen in parallel analyses.

CONCLUSIONS: The use of aspirin was associated with significantly lower indices of liver fibrosis among US adults with suspected chronic liver diseases. Aspirin and other anti-platelet drugs warrant further investigation for the prevention and treatment of liver fibrosis.

INTRODUCTION: Production of very low-density lipoprotein (VLDL) is increased in states of metabolic syndrome, leading to hypertriglyceridemia. However, metabolic syndrome is often associated with non-alcoholic fatty liver disease, which leads to liver fibrosis and inflammation that may decrease VLDL production. In this study, we aim to determine the interactive impact on VLDL profiles from insulin resistance, impairment in liver synthetic function and inflammation.

METHODS: We examined cross-sectional associations of insulin sensitivity, inflammation, and liver synthetic function with VLDL particle (VLDL-P) concentration and size among 1,850 older adults in the Cardiovascular Health Study.

RESULTS: Indices for high insulin sensitivity and low liver synthetic function were associated with lower concentrations of VLDL-P. In addition, insulin resistance preferentially increased concentration of large VLDL and was associated with mean VLDL size. Indices for inflammation however demonstrated a nonlinear relationship with both VLDL-P concentration and VLDL size. When mutually adjusted, one standard deviation (SD) increment in Matsuda index and C-reactive protein (CRP) were associated with 4.9 nmol/L (-8.2 to -1.5, p=0.005) and 6.3 nmol/L (-11.0 to -1.6, p=0.009) lower VLDL-P concentration respectively. In contrast, one-SD increment in factor VII, a marker for liver synthetic function, was associated with 16.9 nmol/L (12.6-21.2, p<0.001) higher VLDL-P concentration. Furthermore, a one-SD increment in the Matsuda index was associated with 1.1 nm (-2.0 to -0.3, p=0.006) smaller mean VLDL size, whereas CRP and factor VII were not associated with VLDL size.

CONCLUSION: Insulin sensitivity, inflammation and markers for liver synthetic function differentially impact VLDL-P concentration and VLDL size. These results underscore the complex effects of insulin resistance and its complications on VLDL production.

BACKGROUND AND AIM: Nonalcoholic fatty liver disease (NAFLD) affects 15-40% of the general population; 10-20% of those patients have a more severe form of the disease known as nonalcoholic steatohepatitis (NASH). Cytokeratin-18 (CK18), released during apoptosis and one of the most studied biomarkers in NASH, can be measured by a number of commercially available kits. We compared serum measurements of the CK18 M30 from two different kits using the same cohort to evaluate the reliability between two test kits.

METHODS: We measured serum levels of CK18 M30 from 185 patients with biopsy-proven NAFLD from a single center from 2009 to 2015, using two different ELISA kits, Test 1 (T1) and Test 2 (T2). Advanced fibrosis was defined as fibrosis stages 3-4 and NASH defined by NAS score ≥ 5.

RESULTS: Mean age was 50.2 years (SD 12.6), 61.1% male and 87% White; 49.6% had NASH and 32.2% advanced fibrosis. There was no significant correlation between measurements from the two kits (p = 0.86, r = 0.01). While T2 predicted NASH and advanced fibrosis, T1 did not. The area under ROC curve for the prediction of NASH was 0.631 for T2 versus 0.500 for T1.

CONCLUSIONS: Measurements from two different CK18 M30 test kits did not correlate with each other. One kit showed statistically significantly higher levels of CK18 M30 in patients with advanced fibrosis and NASH, while the other kit did not. With the increasing use of CK18 as a biomarker in NASH, it is important to standardize the different kits as it could greatly bias the results.

BACKGROUND & AIMS: T-helper-type 17 (Th17) cells are involved in autoimmune tissue damage. CD39 is an ectonucleotidase that catalyzes extracellular ATP/ADP hydrolysis, culminating in the generation of immunosuppressive adenosine. Functional CD39 expression confers immunosuppressive properties upon immune cells. As the proportion of CD39 lymphocytes is decreased in juvenile autoimmune liver disease (AILD), we have explored whether decreased CD39 expression is present on Th17 cells and whether this phenomenon is associated with heightened effector function and inflammation.

METHODS: Thirty-eight patients with juvenile AILD (22 autoimmune hepatitis and 16 autoimmune sclerosing cholangitis), 8 disease controls (DC) and 16 healthy subjects (HS) were studied. Peripheral blood cell phenotype was determined by flow cytometry; ability to suppress by inhibition of cell proliferation/effector cytokine production; ectoenzymatic activity by thin layer chromatography; expression of adenosine receptor, adenosine deaminase (ADA) and phosphodiesterases (PDE) by quantitative real-time PCR or by Western Blot.

RESULTS: CD39(+) Th17 (Th17(CD39+)) cells from HS appear activated and contain high frequencies of lymphocytes producing regulatory cytokines. In AILD, however, Th17(CD39+) cells are markedly diminished and fail to generate AMP/adenosine, thereby limiting control of both target cell proliferation and IL-17 production. When compared to HS, Th17 cells from AILD patients also show lower A2A adenosine receptor expression while displaying similar levels of PDE4A, PDE4B and ADA. Only rare Th17(CD39+) cells are observed by liver immunohistochemistry.

CONCLUSIONS: Th17(CD39+) cells in juvenile AILD are both quantitatively decreased and qualitatively deficient. Low levels CD39 and A2A expression may contribute to the perpetuation of Th17 cell effector properties and unfettered inflammation in this disease.

BACKGROUND & AIMS: A major challenge in the management of nonalcoholic fatty liver disease (NAFLD) is to identify patients with nonalcoholic steatohepatitis (NASH) and early liver fibrosis. The progression of NAFLD is accompanied by distinctive changes in very low density lipoprotein (VLDL), a lipoprotein particle produced exclusively in the liver. Herein, we sought to determine the characteristics of VLDL profiles associated with NASH and liver fibrosis.

METHODS: We evaluated VLDL profiles of 128 patients from a single centre NAFLD registry, and examined VLDL size, total and subclass VLDL concentrations in relation to NAFLD activity score (NAS), steatohepatitis and liver fibrosis as determined by liver biopsy.

RESULTS: A near linear relationship was observed between mean VLDL particle size and NAFLD activity score (NAS). In multivariate models, VLDL particle size was significantly associated with both NAS and NASH, after adjustment for BMI and diabetes. A decrease in small VLDL particle concentration was associated with more advanced liver fibrosis. In receiver operative characteristic analyses, mean VLDL size performed similarly to cytokeratin 18 in predicting NASH, whereas small VLDL particle concentration had similar performance to NAFLD fibrosis score in predicting stage 2 or above liver fibrosis.

CONCLUSIONS: The increase in mean VLDL size in NASH and decrease in small VLDL particle concentration in liver fibrosis likely reflect changes in the number and state of hepatocytes associated with NASH and fibrosis. In addition to its value in risk stratification of cardiovascular diseases, circulating VLDL profile may provide information for the staging of NAFLD disease severity.

Hepatic encephalopathy (HE) is one of the most important complications of cirrhosis and portal hypertension. Although the etiology is incompletely understood, it has been linked to ammonia directly and indirectly. Our goal is to review for the clinician the mechanisms behind hyperammonemia and the pathogenesis of HE to explain the rationale for its therapy. We reviewed articles collected through a search of MEDLINE/PubMed, Cochrane Database of Systematic Reviews, and Google Scholar between October 1, 1948, and December 8, 2014, and by a manual search of citations within retrieved articles. Search terms included hepatic encephalopathy, ammonia hypothesis, brain and ammonia, liver failure and ammonia, acute-on-chronic liver failure and ammonia, cirrhosis and ammonia, portosytemic shunt, ammonia and lactulose, rifaximin, zinc, and nutrition. Ammonia homeostatsis is a multiorgan process involving the liver, brain, kidneys, and muscle as well as the gastrointestinal tract. Indeed, hyperammonemia may be the first clue to poor functional reserves, malnutrition, and impending multiorgan dysfunction. Furthermore, the neuropathology of ammonia is critically linked to states of systemic inflammation and endotoxemia. Given the complex interplay among ammonia, inflammation, and other factors, ammonia levels have questionable utility in the staging of HE. The use of nonabsorbable disaccharides, antibiotics, and probiotics reduces gut ammoniagenesis and, in the case of antibiotics and probiotics, systemic inflammation. Nutritional support preserves urea cycle function and prevents wasting of skeletal muscle, a significant site of ammonia metabolism. Correction of hypokalemia, hypovolemia, and acidosis further assists in the reduction of ammonia production in the kidney. Finally, early and aggressive treatment of infection, avoidance of sedatives, and modification of portosystemic shunts are also helpful in reducing the neurocognitive effects of hyperammonemia. Refining the ammonia hypothesis to account for these other factors instructs a solid foundation for the effective treatment and prevention of hepatic encephalopathy.

BACKGROUND: Elevated fasting triglyceride is often associated with metabolic syndrome and non-alcoholic fatty liver disease (NAFLD), the most common form of chronic liver disease. On the other hand, as liver disease progresses, patients may develop hepatocellular dysfunction that impairs triglyceride production.

AIM: To test the hypothesis that lower fasting triglyceride levels may paradoxically indicate more advanced liver disease.

METHODS: A cross-sectional analysis of 11 947 adults aged 20 years or older without chronic viral hepatitis from the National Health and Nutrition Examination Survey 1999-2010 was performed to analyze the relationships between fasting triglyceride levels and five validated non-invasive indices of liver fibrosis, including Fibrosis 4 Score (FIB4), NAFLD Fibrosis Score (NFS), Ast-Platelet Ration Index, AST/ALT ratio and BARD.

RESULTS: Low-fasting triglyceride levels were consistently associated with elevated liver fibrosis indices. Individuals in the lowest quintile of triglycerides (TG) had an adjusted odds ratio (OR) of 3.0 (95% CI, 1.7-5.2; P < 0.001) for advanced fibrosis estimated by FIB4 score and OR of 1.8 (95% Cl, 1.2-2.7; P = 0.009) estimated by NFS, compared to individuals in the highest quintile. This association remained highly significant when restricted to individuals with abnormal LFTs from suspected NAFLD. This inverse relationship was continuous, and more pronounced among men and whites (P interaction <0.001 and 0.008 respectively), but not modified by age or body mass index. In addition, fasting TG had a stronger, more direct association with liver fibrosis indices than did albumin or total bilirubin.

CONCLUSIONS: Fasting triglyceride levels were inversely associated with liver fibrosis indicators in American adults, especially among white men. Our findings suggest that sequential lipid measurements may serve as a useful disease marker in the management of chronic liver disease patients.