Combination Therapy of Endoscopic Gastric Remodeling with GLP-1RA for the Treatment of MASLD.

PURPOSE: The mainstay of treatment for metabolic dysfunction-associated steatotic liver disease (MASLD) is weight loss. Endoscopic gastric remodeling (EGR) and glucagon-like peptide-1 receptor agonist (GLP-1RA) are effective weight loss therapies. This study aims to assess the effect of combining EGR with GLP-1RA on liver-related outcomes and weight profile. MATERIALS AND METHODS: This is a retrospective study of a prospectively collected registry of patients with MASLD and compensated advanced chronic liver disease (cACLD) who underwent EGR. Patients were categorized as (1) monotherapy: EGR alone and (2) combination therapy: GLP-1RA prescribed within 6 months prior to or after EGR. Outcomes included changes in noninvasive tests of hepatic fibrosis, weight profile, and insulin resistance status at 12 months. RESULTS: Thirty patients (body mass index 40.7 ± 9.3 kg/m2) were included. Of these, 12 patients (40%) underwent EGR monotherapy, and 18 patients (60%) underwent EGR + GLP-1RA combination therapy. Combination therapy group experienced greater improvements in fibrosis compared to monotherapy group (alanine aminotransferase: reduction by 55 ± 23% vs 29 ± 22% (p = 0.008), NAFLD fibrosis score: reduction by 181 ± 182% vs 30 ± 83% (p = 0.04), liver stiffness measurement on transient elastography: reduction by 54 ± 12% vs 14 ± 45% (p = 0.05)). There were greater reductions in hemoglobin A1c and homeostatic model assessment for insulin resistance in combination therapy compared to monotherapy (p < 0.05). At 12 months, the combination therapy group experienced 18.2 ± 6.6% TWL, while monotherapy group experienced 9.6 ± 3.3% TWL (p = 0.004). CONCLUSIONS: In patients with MASLD and cACLD, combination of EGR with GLP-1RA is associated with greater improvements in hepatic fibrosis, weight profile, and insulin resistance compared to EGR alone.

Outcomes of High-Grade Immune Checkpoint Inhibitor Hepatitis in Hospitalized and Nonhospitalized Patients.

BACKGROUND & AIMS: Guidelines recommend hospitalization for severe immune checkpoint inhibitor (ICI) hepatitis. We compared patient outcomes in the inpatient versus outpatient settings. METHODS: We conducted a multicenter, retrospective cohort study of 294 ICI-treated patients who developed grade 3-4 ICI hepatitis. The primary outcome was time to alanine aminotransferase (ALT) normalization (≤40); secondary outcomes included time to ALT ≤100 U/L and time to death. To account for confounding by indication, inverse probability of treatment weighting was applied to perform Cox regression. A sensitivity analysis was performed excluding patients with grade 4 hepatitis. RESULTS: One hundred and sixty-six patients (56.5%) were hospitalized for a median of 6 (interquartile range, 3-11) days. On inverse probability of treatment weighting Cox regression, hospitalization was not associated with time to ALT normalization (hazard ratio [HR], 1.11; 95% confidence interval [CI], 0.86-1.43; P = .436) or time to ALT ≤100 U/L (HR, 1.11; 95% CI, 0.86-1.43; P = .420). In the sensitivity analysis limited to patients with grade 3 hepatitis, hospitalization was also not associated with time to ALT normalization (HR, 1.11; 95% CI, 0.83-1.50; P = .474) or time to ALT ≤100 U/L (HR, 1.19; 95% CI, 0.90-1.58; P = .225). In a subgroup analysis of 152 patients with melanoma, hospitalization was not associated with reduced risk of all-cause death (HR, 0.93; 95% CI, 0.53-1.64; P = .798). Notably, despite their Common Terminology Criteria for Adverse Events classification of high-grade hepatitis, 94% of patients had "mild" liver injury based on International Drug-Induced Liver Injury Criteria. CONCLUSIONS: Hospitalization of patients with high-grade ICI hepatitis was not associated with faster hepatitis resolution and did not affect mortality. Routine hospitalization may not be necessary in all patients with high-grade ICI hepatitis and Common Terminology Criteria for Adverse Events criteria may overestimate severity of liver injury.

The effect of endoscopic gastric plication on portosystemic pressure gradient in patients with nonalcoholic fatty liver disease and compensated advanced chronic liver disease.

BACKGROUND: The goals of therapy for patients with nonalcoholic fatty liver disease and compensated advanced chronic liver disease include weight loss and reduction of the portosystemic pressure gradient (PPG) to decrease the risk of hepatic decompensation. Endoscopic gastric plication (EGP) is an effective endoscopic weight loss procedure. This study aimed to assess the effect of EGP on PPG. METHODS: In this prospective pilot study, patients with nonalcoholic fatty liver disease and compensated advanced chronic liver disease underwent endoscopic ultrasound-guided PPG measurement prior to and at 6 months following EGP. Primary outcomes were the change in PPG and proportion of patients experiencing ≥ 20 % reduction in PPG at 6 months. Secondary outcomes included percent total weight loss (TWL) and changes in noninvasive tests of fibrosis. RESULTS: 20 patients were included. Baseline median body mass index and liver stiffness measurement were 40.2 kg/m2 (range 30.1-56.7) and 14.7 kPa (range 8.2-36), respectively. At 6 months, median PPG decreased from 5.4 mmHg (range 0.7-19.6) to 1.8 mmHg (range 0.4-17.6) (P = 0.002), with 79 % (11/14) experiencing ≥ 20 % reduction. Patients experienced 12.5 % (6.5 %-26.1 %) TWL (P < 0.001) at 6 months, with 89 % (17/19) achieving ≥ 7 % and 68 % (13/19) achieving ≥ 10 % TWL. There were significant improvements in noninvasive tests of fibrosis. CONCLUSION: EGP appeared to be effective at reducing PPG in patients with nonalcoholic fatty liver disease and compensated advanced chronic liver disease.

Liver Pathology Related to Onco-Therapeutic Agents.

Oncotherapeutic agents can cause a wide range of liver injuries from elevated liver functions tests to fulminant liver failure. In this review, we emphasize a newer generation of drugs including immune checkpoint inhibitors, protein kinase inhibitors, monoclonal antibodies, and hormonal therapy. A few conventional chemotherapy agents are also discussed.

Early Liver Specialist Consultation is Associated With Faster Biochemical Resolution of Severe Immune Checkpoint Inhibitor-Induced Hepatitis.

BACKGROUND: We evaluated the impact of gastroenterology/hepatology consultation, as recommended by guidelines, on the management of severe immune checkpoint inhibitor (ICI)-induced hepatitis. METHODS: We conducted a multicenter, retrospective cohort study of 294 patients who developed grade ≥3 (alanine aminotransferase [ALT] >200 U/L) ICI-induced hepatitis, with early gastroenterology/hepatology consultation defined as occurring within 7 days of diagnosis. The primary outcome was time to ALT normalization (≤40 U/L), and the secondary outcome was time to ALT improvement to ≤100 U/L. RESULTS: A total of 117 patients received early consultation. In the 213 patients with steroid-responsive hepatitis, early consultation was not associated with faster ALT normalization (hazard ratio [HR], 1.12; 95% CI, 0.83-1.51; P=.453). A total of 81 patients developed steroid-refractory hepatitis, with 44 (54.3%) receiving early consultation. In contrast to the patients whose hepatitis responded to steroid treatment, early consultation in those with steroid-refractory disease was associated with faster ALT normalization (HR, 1.89; 95% CI, 1.12-3.19; P=.017) and ALT improvement to ≤100 U/L (HR, 1.72; 95% CI, 1.04-2.84; P=.034). Notably, additional immunosuppressive therapy for steroid-refractory disease was initiated sooner after diagnosis in the early consult group (median 7.5 vs 13.0 days; log-rank P=.001). When time to additional immunosuppression was added as a covariate to the Cox model in mediation analysis, early consultation was no longer associated with time to ALT normalization (HR, 1.39; 95% CI, 0.82-2.38; P=.226) or with time to ALT improvement to ≤100 U/L (HR, 1.25; 95% CI, 0.74-2.11; P=.404). Time to additional immunosuppression remained associated with faster ALT normalization and faster ALT improvement to ≤100 U/L in the model, suggesting that the faster hepatitis resolution in the early consultation group was primarily attributable to earlier initiation of additional immunosuppression. CONCLUSIONS: Early gastroenterology/hepatology consultation is associated with faster resolution of biochemical abnormalities in patients with steroid-refractory hepatitis. This beneficial effect appears to be mediated by earlier initiation of additional immunosuppressive therapy in those receiving early consultation.

Regression of Hepatic Fibrosis After Endoscopic Gastric Plication in Nonalcoholic Fatty Liver Disease.

INTRODUCTION: Fibrosis stage is the strongest predictor of mortality in patients with nonalcoholic fatty liver disease (NAFLD). There is currently no approved therapy that specifically targets fibrosis. This study aims to assess the effect of endoscopic gastric plication on hepatic fibrosis in patients with underlying NAFLD. METHODS: This is a retrospective analysis of prospectively collected registry of patients with obesity and NAFLD with clinically significant hepatic fibrosis (≥F2) who underwent endoscopic gastric plication. Full-thickness plications were placed in the gastric body using a commercially available platform to reduce the gastric volume. The primary outcome included various noninvasive tests (NITs) of hepatic fibrosis based on clinical chemistry and/or imaging. The secondary outcomes included NITs of hepatic steatosis, other metabolic outcomes, including hemoglobin A1c, insulin resistance, and total weight loss (TWL), and adverse events. RESULTS: Forty-five patients (age 51 ± 13 years and body mass index 40.7 ± 6.9 kg/m 2 ) were included. All patients underwent endoscopic gastric plication successfully. At 6-12 months, there were significant reductions in biochemistries (alanine aminotransferase: 49.7 ± 36.8 U/L to 24.2 ± 12.0 U/L [ P < 0.0001], aspartate aminotransferase: 39.1 ± 24.1 U/L to 24.1 ± 10.0 U/L [ P < 0.0001]), composite fibrosis score (NAFLD fibrosis score: 0.48 ± 1.51 to -1.18 ± 1.56 [ P < 0.0001], fibrosis-4 index: 1.4 ± 1.2 to 1.2 ± 0.7 [ P = 0.03]), and imaging-based markers of fibrosis (vibration-controlled transient elastography: 13.9 ± 7.5 kPa to 8.9 ± 4.8 kPa ( P < 0.0001) and Agile 3+: 0.53 ± 0.28 to 0.37 ± 0.28 [ P = 0.001]). There were significant reductions in controlled attenuation parameter, Homeostatic Model Assessment for Insulin Resistance, and hemoglobin A1c ( P < 0.05 for all). At 12 months, patients experienced 15.5% ± 7.9% TWL, with 63% reaching at least 10% TWL. DISCUSSION: Endoscopic gastric plication seems effective at treating NAFLD, with significant reduction in NITs of hepatic fibrosis even in patients with cirrhosis.

Effect of corticosteroid dosing on outcomes in high-grade immune checkpoint inhibitor hepatitis.

BACKGROUND AND AIMS: Consensus guidelines recommend high-dose corticosteroids (1-2 mg/kg/day methylprednisolone equivalents) for treating grade ≥3 immune checkpoint inhibitor (ICI) hepatitis. We examined the effect of corticosteroid dosing on time to alanine aminotransferase (ALT) normalization, need for additional immunosuppression, and steroid-related complications. APPROACH AND RESULTS: We conducted a retrospective cohort study of 215 ICI-treated patients from 2010 to 2020 who developed grade ≥3 (ALT > 200 U/L) ICI hepatitis. Patients were grouped by initial corticosteroid dose (≥1.5 mg/kg or <1.5 mg/kg methylprednisolone equivalents). Propensity scores were calculated predicting the risk of receiving the higher steroid dose and used in inverse probability of treatment weighted (IPTW) logistic or Cox regression. The 87 patients in the ≥1.5 mg/kg group received higher initial (2.0 vs. 0.8 mg/kg/day, p < 0.001) and maximum (2.0 vs. 1.0 mg/kg/day, p < 0.001) steroid doses than the 128 patients in the <1.5 mg/kg group. There was no difference between the higher versus lower-dose groups in development of steroid-refractory hepatitis (OR 1.22, 95% CI 0.79-1.89, p = 0.365) on IPTW-logistic regression. In patients with steroid-responsive disease, there was no difference between the two groups in time to ALT normalization using either standard Cox regression (HR 1.02, 95% CI 0.72-1.45, p = 0.903) or IPTW-Cox regression (HR 1.09, 95% CI 0.78-1.51, p = 0.610). The ≥1.5 mg/kg group had longer exposure to corticosteroids (median 60 vs. 44 days, p = 0.005) and higher incidences of infection (18.4% vs. 7.0%, relative risk [RR] 2.6, 95% CI 1.2-5.6, p = 0.011) and hyperglycemia requiring treatment (23.3% vs. 7.8%, RR 3.0, 95% CI 1.5-6.0, p = 0.001). CONCLUSIONS: In patients with high-grade ICI hepatitis, initial treatment with 1 mg/kg/day methylprednisolone equivalents provides similar hepatitis outcomes with reduced risk of steroid-related complications when compared with higher-dose regimens.

Association of Terry Nails With Liver Cirrhosis.

INTRODUCTION: We looked at the association between Terry nails and liver cirrhosis in an ambulatory population from hepatology and gastroenterology clinics. METHODS: We prospectively investigated the prevalence and determinants of Terry nails in 1,000 consecutive patients from hepatology and gastroenterology clinics at 2 institutions between May 2016 and February 2020. RESULTS: A total of 117 subjects manifested Terry nails, with a 25.6% prevalence in patients with cirrhosis. When adjusted for age, heart failure, diabetes mellitus type 2, and chronic liver disease, cirrhosis was the only significant correlate (odds ratio 5.7 [95% confidence interval 3.3-9.8]), irrespective of liver disease etiology, with a strong association with hepatic fibrosis stage (P < 0.0001). DISCUSSION: Sensitivity and specificity of Terry nails for cirrhosis (25.8%, 92.7%) was similar to palmar erythema but less than spider angioma.

Bleeding Outcomes Following Transesophageal Echocardiography in Patients With Cirrhosis and Esophageal Varices.

Despite scant evidence, current guidelines indicate that esophageal varices are a relative contraindication to transesophageal echocardiography (TEE). The aim of this study is to compare the risk of gastrointestinal bleeding following TEE among cirrhotic patients with and without endoscopically-documented esophageal varices. This is a retrospective analysis of patients with cirrhosis who underwent upper endoscopy within 4 years of TEE at five institutions between January 2000 and March 2020. Primary outcome was overt gastrointestinal bleeding. Secondary outcomes were hemoglobin decline by at least 2 g/dL or blood transfusion within 48 hours following TEE. Of the 191 patients, 79 (41.4%) had esophageal varices (30.4% large). No patient experienced a primary outcome. Secondary outcomes occurred in 52 (27.2%): 28 (35.4%) with esophageal varices and 24 (21.4%) without varices. After propensity-score covariate adjustment, the odds ratio for a secondary outcome in patients with esophageal varices was 1.49 (95% confidence interval 0.74-2.99). Restricting analysis to those who underwent endoscopy within 1 year of TEE did not significantly alter results. The risk of a secondary outcome was identical between patients who had upper endoscopy prior (27.5%) versus subsequent (26.7%; P = 1.00) to TEE. Conclusions: Among patients with cirrhosis, there was no overt gastrointestinal bleeding after TEE. The likelihood of a 2 g/dL decline in hemoglobin or blood transfusion within 48 hours following TEE was not significantly higher in patients with esophageal varices after controlling for confounders. Patients who underwent upper endoscopy before TEE did not manifest a lower risk of secondary outcomes versus those who had endoscopy after TEE, suggesting that routine preprocedural endoscopy is of marginal utility.

Association Between Atazanavir-Induced Hyperbilirubinemia and Cardiovascular Disease in Patients Infected with HIV.

BACKGROUND: Serum bilirubin is inversely associated with cardiovascular risk. Atazanavir, an HIV protease inhibitor that competitively inhibits bilirubin conjugation, provides a unique opportunity to examine whether selectively increasing bilirubin is cardioprotective. We sought to determine whether patients receiving atazanavir manifest a reduced risk of cardiovascular disease compared with those receiving darunavir, an HIV protease inhibitor that does not increase serum bilirubin. METHODS AND RESULTS: This was a retrospective cohort study of 1020 patients with HIV. The main outcome was time to myocardial infarction or ischemic stroke. Mean follow-up was 6.6±3.4 years, with 516 receiving atazanavir and 504 darunavir. Atazanavir patients exhibited significantly higher serum total bilirubin (1.7 versus 0.4 mg/dL; P<0.001) and longer mean time to ischemic event (10.2 versus 9.4 years; P<0.001). On Cox regression, atazanavir treatment (hazard ratio [HR], 0.38; 95% CI, 0.21-0.71; P=0.002) and serum bilirubin (HR, 0.60; 95% CI, 0.41-0.89; P=0.011) were independently associated with a lower risk of an ischemic event. Notably, when atazanavir and bilirubin were included together in the Cox regression model, atazanavir lost significance (HR, 0.55; 95% CI, 0.24-1.29; P=0.169) consistent with bilirubin being an intermediate variable on the causal pathway between atazanavir and its effect on cardiovascular disease. Patients on atazanavir also had a significantly lower risk of developing new cardiovascular disease (HR, 0.53; 95% CI, 0.33-0.86; P=0.010) and longer mean time to death (12.2 versus 10.8 years; P<0.001). CONCLUSIONS: Patients with HIV on atazanavir manifest a decreased risk of cardiovascular disease when compared with those on darunavir, an effect that appears to be mediated by serum bilirubin.

Outcomes after resumption of immune checkpoint inhibitor therapy after high-grade immune-mediated hepatitis.

BACKGROUND: In the current study, the authors assessed the risks and outcomes of immune checkpoint inhibitor (ICI) rechallenge in patients with resolved grade 3 to 4 ICI hepatitis because current guidelines recommend permanent ICI discontinuation in these patients. METHODS: The authors performed a retrospective cohort study from 2010 through 2019 of patients with melanoma who were treated with ≥1 ICIs and who recovered from grade 3 to 4 ICI hepatitis. The primary outcome was hepatitis recurrence and the secondary outcome was the development of any immune-related adverse event (irAE) requiring the discontinuation of ICI rechallenge. Best overall response and time to all-cause death were compared between the patients who did and those who did not undergo ICI rechallenge. Grading was performed using the National Cancer Institute Common Terminology Criteria for Adverse Events (version 5.0). RESULTS: Of the 102 patients with melanoma who developed high-grade ICI hepatitis, 31 underwent ICI rechallenge. Although 15 of 31 patients (48%) developed an irAE of any grade, only 6 patients (19%) required ICI discontinuation due to irAE severity (4 of 29 patients [14%] rechallenged with anti-PD-1 or anti-PD-L1 and 2 of 2 patients [100%] rechallenged with ipilimumab). Recurrent hepatitis accounted for 4 of these 6 cases. Rechallenged patients who did not require ICI discontinuation were found to be significantly less likely to receive ipilimumab rather than anti-PD-1 or anti-PD-L1 monotherapy (0% vs 33%; relative risk (RR), 0.1 [95% CI, 0.1-0.3; P = .032]) and significantly less likely to be rechallenged with their original ICI (8% vs 50%; RR, 0.2 [95% CI, 0.1-0.7; P = .038]). There was no difference noted with regard to best overall response or time to death between rechallenged and non-rechallenged patients. CONCLUSIONS: ICI therapy can be resumed in patients with melanoma who have recovered from grade 3 to 4 ICI hepatitis with a modest risk of serious irAEs. It remains unclear whether ICI retreatment improves clinical outcomes.

Liver function and prognosis, and influence of sacubitril/valsartan in patients with heart failure with reduced ejection fraction.

AIMS: The prevalence of liver function abnormalities is common in patients with heart failure (HF) with reduced ejection fraction (HFrEF). We assessed the impact of liver function on prognosis and the effect of sacubitril/valsartan on measures of liver function in patients with HFrEF. METHODS AND RESULTS: The PARADIGM-HF trial was a randomized, double-blind, active treatment-controlled trial. We included 8232 HFrEF patients with available measures of liver function, including transaminases, alkaline phosphatase (ALP) and bilirubin; the primary endpoint was a composite of HF hospitalization and cardiovascular (CV) death. At screening, 11.6% of study patients had total bilirubin above the upper limit of normal (20.5 µmol/L) and 9.2% had ALP above the upper limit of normal (123 IU/L). Although ALP and albumin were associated with an increased risk of outcomes, among conventional test of liver function, total bilirubin was the strongest predictor for the primary endpoint [hazard ratio (HR) 1.10; 95% confidence interval (CI) 1.04-1.15; P < 0.001], HF hospitalization (HR 1.14; 95% CI 1.07-1.22; P < 0.001); CV death (HR 1.07; 95% CI 1.00-1.14; P = 0.040), and all-cause death (HR 1.08; 95% CI 1.02-1.14; P = 0.009). All conventional measures of liver function were significantly improved in the sacubitril/valsartan group compared with the enalapril group after randomization (between-group reduction: total bilirubin 2.4%, 95% CI 0.7-4.2%, P = 0.007; aspartate aminotransferase 7.9%, 95% CI 6.7-9.0%, P < 0.001; alanine aminotransferase 7.7%; 95% CI 6.2-9.3%, P < 0.001; ALP 5.4%, 95% CI 4.4-6.4%, P < 0.001). CONCLUSION: Total bilirubin was a significant and independent predictor of CV death or HF hospitalization and all-cause mortality in patients with HFrEF enrolled in PARADIGM-HF. Sacubitril/valsartan improved measures of liver function compared with enalapril.

Influence of Type 2 Diabetes Mellitus and Preoperative Hemoglobin A1c Levels on Outcomes of Liver Transplantation.

Liver transplant centers often establish hemoglobin A1c (HbA1C) criteria for candidates with type 2 diabetes mellitus (T2DM) based on data from other surgical specialties showing worse outcomes in patients with poor glycemic control. However, because of the reduced reliability of HbA1C in cirrhosis, it is unclear whether pretransplant HbA1C values are predictive of postoperative complications in liver recipients. We retrospectively examined the association between preoperative HbA1C and postoperative outcomes in 173 consecutive patients who underwent liver transplantation at the University of Cincinnati Medical Center between August 2012 and March 2015. Demographic correlates of pretransplant HbA1C included age, T2DM, native Model for End-Stage Liver Disease, hemoglobin, serum albumin, and nonalcoholic steatohepatitis as the indication for transplantation. No association was identified between pretransplant HbA1C and most outcome measures, including survival, length of stay, reoperation or readmission rates, rejection, bacteremia, and viremia. Significant correlates of HbA1C in liver recipients with diabetes were posttransplant insulin requirement and anastomotic biliary stricture formation. On multivariate analysis, HbA1C was the sole determinant of biliary strictures, with patients in the highest quartile (HbA1C >7.3%) exhibiting a 4-fold increased risk. Correlation of HbA1C with morning blood glucose levels was much tighter after versus before transplantation. Conclusion: Preoperative HbA1C is predictive of anastomotic biliary stricture formation and the need for insulin following liver transplantation.

Hepatitis C transmission from seropositive, nonviremic donors to non-hepatitis C liver transplant recipients.

Breakthroughs in hepatitis C virus (HCV) treatment and rising rates of intravenous drug use have led to an increase in the number of organ donors who are HCV antibody-positive but serum nucleic acid test (NAT)-negative. The risk of HCV transmission from the liver grafts of these donors to recipients is unknown. To estimate the incidence of HCV transmission, we prospectively followed 26 consecutive HCV antibody-negative (n = 25) or NAT-negative (n = 1) transplant recipients who received a liver graft from donors who were HCV antibody-positive but serum NAT-negative between March 2016 and March 2017. HCV transmission was considered to have occurred if recipients exhibited a positive HCV PCR test by 3 months following transplantation. Drug overdose was listed as the cause of death in 15 (60%) of the donors. One recipient died 18 days after transplantation from primary graft nonfunction and was excluded. Of the remaining 25 recipients, HCV transmission occurred in 4 (16%), at a median follow-up of 11 months, all from donors who died of drug overdose. Three of these patients were treated with direct-acting antiviral therapy, with two achieving a sustained virologic response and one an end-of-treatment response. One patient with HCV transmission died after a complicated postoperative course and did not receive antiviral therapy. CONCLUSION: In this prospective cohort of non-HCV liver recipients receiving grafts from HCV antibody-positive/NAT-negative donors, the incidence of HCV transmission was 16%, with the highest risk conferred by donors who died of drug overdose; given the availability of safe and highly effective antiviral therapies, use of such organs could be considered to expand the donor pool. (Hepatology 2018;67:1673-1682).

Bilirubin Prevents Atherosclerotic Lesion Formation in Low-Density Lipoprotein Receptor-Deficient Mice by Inhibiting Endothelial VCAM-1 and ICAM-1 Signaling.

BACKGROUND: Numerous epidemiological studies support an inverse association between serum bilirubin levels and the incidence of cardiovascular disease; however, the mechanism(s) by which bilirubin may protect against atherosclerosis is undefined. The goals of the present investigations were to assess the ability of bilirubin to prevent atherosclerotic plaque formation in low-density lipoprotein receptor-deficient (Ldlr-/- ) mice and elucidate the molecular processes underlying this effect. METHODS AND RESULTS: Bilirubin, at physiological concentrations (≤20 µmol/L), dose-dependently inhibits THP-1 monocyte migration across tumor necrosis factor α-activated human umbilical vein endothelial cell monolayers without altering leukocyte binding or cytokine production. A potent antioxidant, bilirubin effectively blocks the generation of cellular reactive oxygen species induced by the cross-linking of endothelial vascular cell adhesion molecule 1 (VCAM-1) or intercellular adhesion molecule 1 (ICAM-1). These findings were validated by treating cells with blocking antibodies or with specific inhibitors of VCAM-1 and ICAM-1 signaling. When administered to Ldlr-/- mice on a Western diet, bilirubin (30 mg/kg intraperitoneally) prevents atherosclerotic plaque formation, but does not alter circulating cholesterol or chemokine levels. Aortic roots from bilirubin-treated animals exhibit reduced lipid and collagen deposition, decreased infiltration of monocytes and lymphocytes, fewer smooth muscle cells, and diminished levels of chlorotyrosine and nitrotyrosine, without changes in VCAM-1 or ICAM-1 expression. CONCLUSIONS: Bilirubin suppresses atherosclerotic plaque formation in Ldlr-/- mice by disrupting endothelial VCAM-1- and ICAM-1-mediated leukocyte migration through the scavenging of reactive oxygen species signaling intermediaries. These findings suggest a potential mechanism for the apparent cardioprotective effects of bilirubin.

Bilirubin acts as an endogenous regulator of inflammation by disrupting adhesion molecule-mediated leukocyte migration.

There is a growing body of evidence that bilirubin, which is generated during the physiological breakdown of heme, exerts potent anti-inflammatory effects. Previous work by our group suggests that bilirubin is able to suppress inflammatory responses by preventing the migration of leukocytes into target tissues through disruption of vascular cell adhesion molecule-1 (VCAM-1)-dependent cell signaling. As VCAM-1 is an important mediator of tissue injury in the dextran sodium sulfate (DSS) murine model of inflammatory colitis, we examined whether bilirubin prevents colonic injury in DSS-treated mice. As anticipated, bilirubin-treated animals manifested significantly less colonic injury and reduced infiltration of inflammatory cells into colon tissues. We further observed that bilirubin administration was associated with a reduced number of eosinophils and monocytes in the small intestine, with a corresponding increase in peripheral blood eosinophilia, regardless of whether mice received DSS. These findings suggest that bilirubin impairs the normal migration of eosinophils into intestinal tissues, as supported by in vitro experiments showing that bilirubin blocks the VCAM-1-dependent movement of Jurkat cells across human endothelial cell monolayers. Taken together, our findings support that bilirubin ameliorates DSS-induced colitis and disrupts the physiological trafficking of leukocytes to the intestine by preventing transmigration across the vascular endothelium, potentially through the inhibition VCAM-1-mediated signaling. Our findings raise the possibility that bilirubin functions as an endogenous regulator of inflammatory responses.

Bilirubin prevents acute DSS-induced colitis by inhibiting leukocyte infiltration and suppressing upregulation of inducible nitric oxide synthase.

Bilirubin is thought to exert anti-inflammatory effects by inhibiting vascular cell adhesion molecule-1 (VCAM-1)-dependent leukocyte migration and by suppressing the expression of inducible nitric oxide synthase (iNOS). As VCAM-1 and iNOS are important mediators of tissue injury in the dextran sodium sulfate (DSS) murine model of inflammatory colitis, we examined whether bilirubin prevents colonic injury in DSS-treated mice. Male C57BL/6 mice were administered 2.5% DSS in the drinking water for 7 days, while simultaneously receiving intraperitoneal injections of bilirubin (30 mg/kg) or potassium phosphate vehicle. Disease activity was monitored, peripheral blood counts and serum nitrate levels were determined, and intestinal specimens were analyzed for histological injury, leukocyte infiltration, and iNOS expression. The effect of bilirubin on IL-5 production by HSB-2 cells and on Jurkat cell transendothelial migration also was determined. DSS-treated mice that simultaneously received bilirubin lost less body weight, had lower serum nitrate levels, and exhibited reduced disease severity than vehicle-treated animals. Concordantly, histopathological analyses revealed that bilirubin-treated mice manifested significantly less colonic injury, including reduced infiltration of eosinophils, lymphocytes, and monocytes, and diminished iNOS expression. Bilirubin administration also was associated with decreased eosinophil and monocyte infiltration into the small intestine, with a corresponding increase in peripheral blood eosinophilia. Bilirubin prevented Jurkat migration but did not alter IL-5 production. In conclusion, bilirubin prevents DSS-induced colitis by inhibiting the migration of leukocytes across the vascular endothelium and by suppressing iNOS expression.