Imprinted immune abnormalities in liver transplant patients cured of hepatitis C with antiviral drugs.

Chronic HCV infection induces interferon and dysregulates immune responses through inflammation and chronic antigenic stimulation. Antiviral drugs can cure HCV, providing a unique opportunity to examine the immunological restoration that does and does not occur when a chronic viral infection is eradicated. We quantified blood cytokines levels and used mass cytometry to immunophenotype peripheral blood mononuclear cells before and after HCV cure in 2 groups of patients and controls. At baseline, serum interferon α and soluble CD163 (a macrophage product) were elevated in both liver transplant and nonliver transplant patients compared to controls; the frequencies of several peripheral blood mononuclear cell populations differed from controls; and programmed death protein 1-positivity was increased in nearly all T cell subsets. Many abnormalities persisted after HCV cure, including elevated programmed death protein 1 expression on CD4 naïve and central memory T cells, elevated soluble CD163, and expansion of the plasmablast/plasma cell compartment. Several myeloid-lineage subsets, including Ag-presenting dendritic cells, remained dysregulated. In mechanistic studies, interferon α treatment increased programmed death protein 1 on human T cells and increased T cell receptor signaling. The data identify immunological abnormalities that persist after curative HCV treatment. Before cure, high levels of interferon α may stimulate programmed death protein 1 expression on human T cells, causing persistent functional changes.

Patients With Autoimmune Hepatitis and Nonalcoholic Fatty Liver Disease: Characteristics, Treatment, and Outcomes.

GOAL: The objective of this study was to characterize an autoimmune hepatitis (AIH)/nonalcoholic fatty liver disease (NAFLD) overlap cohort, determine if they received standard of care treatment, and delineate their outcomes in comparison with patients with AIH or NAFLD alone. BACKGROUND: AIH is a relatively rare and heterogeneously presenting liver disease of unknown etiology. NAFLD is a leading cause of liver disease worldwide. AIH treatment includes steroids, which have adverse metabolic effects that can worsen NAFLD. No treatment guidelines are available to mitigate this side on AIH/NAFLD overlap patients. Few studies to date have examined these patients' characteristics, management practices, and outcomes. MATERIALS AND METHODS: A single-center, retrospective chart review study examining biopsy-proven AIH/NAFLD, AIH, and NAFLD patients. Characteristics, treatment, and 1- and 3-year outcomes (all-cause mortality, need for liver transplantation, or decompensated cirrhosis) were evaluated. RESULTS: A total of 72 patients (36.1% AIH/NAFLD, 34.7% AIH, and 29.2% NAFLD) were included. AIH/NAFLD patients were found to be more often Hispanic/Latino, female, and with lower liver aminotransaminases, immunoglobulin G, and anti-smooth muscle antibody positivity. AIH/NAFLD patients were less likely to receive standard of care treatment. No significant differences in outcomes were seen between AIH/NAFLD and either AIH or NAFLD. CONCLUSIONS: Our study demonstrated that AIH/NAFLD patients have unique characteristics and are less likely to receive standard of care treatment compared with patients with AIH alone. Despite this, no difference in outcomes (all-cause mortality, need for liver transplantation, or decompensated cirrhosis) was seen. Given NAFLD's rising prevalence, AIH/NAFLD cases will likely increase, and may benefit from alternative treatment guidelines to prevent worsening of NAFLD.

Outcome of COVID-19 in Patients With Autoimmune Hepatitis: An International Multicenter Study.

BACKGROUND AND AIMS: Data regarding outcome of COVID-19 in patients with autoimmune hepatitis (AIH) are lacking. APPROACH AND RESULTS: We performed a retrospective study on patients with AIH and COVID-19 from 34 centers in Europe and the Americas. We analyzed factors associated with severe COVID-19 outcomes, defined as the need for mechanical ventilation, intensive care admission, and/or death. The outcomes of patients with AIH were compared to a propensity score-matched cohort of patients without AIH but with chronic liver diseases (CLD) and COVID-19. The frequency and clinical significance of new-onset liver injury (alanine aminotransferase > 2 × the upper limit of normal) during COVID-19 was also evaluated. We included 110 patients with AIH (80% female) with a median age of 49 (range, 18-85) years at COVID-19 diagnosis. New-onset liver injury was observed in 37.1% (33/89) of the patients. Use of antivirals was associated with liver injury (P = 0.041; OR, 3.36; 95% CI, 1.05-10.78), while continued immunosuppression during COVID-19 was associated with a lower rate of liver injury (P = 0.009; OR, 0.26; 95% CI, 0.09-0.71). The rates of severe COVID-19 (15.5% versus 20.2%, P = 0.231) and all-cause mortality (10% versus 11.5%, P = 0.852) were not different between AIH and non-AIH CLD. Cirrhosis was an independent predictor of severe COVID-19 in patients with AIH (P < 0.001; OR, 17.46; 95% CI, 4.22-72.13). Continuation of immunosuppression or presence of liver injury during COVID-19 was not associated with severe COVID-19. CONCLUSIONS: This international, multicenter study reveals that patients with AIH were not at risk for worse outcomes with COVID-19 than other causes of CLD. Cirrhosis was the strongest predictor for severe COVID-19 in patients with AIH. Maintenance of immunosuppression during COVID-19 was not associated with increased risk for severe COVID-19 but did lower the risk for new-onset liver injury during COVID-19.

Outcomes following SARS-CoV-2 infection in patients with chronic liver disease: An international registry study.

BACKGROUND & AIMS: Chronic liver disease (CLD) and cirrhosis are associated with immune dysregulation, leading to concerns that affected patients may be at risk of adverse outcomes following SARS-CoV-2 infection. We aimed to determine the impact of COVID-19 on patients with pre-existing liver disease, which currently remains ill-defined. METHODS: Between 25th March and 8th July 2020, data on 745 patients with CLD and SARS-CoV-2 (including 386 with and 359 without cirrhosis) were collected by 2 international registries and compared to data on non-CLD patients with SARS-CoV-2 from a UK hospital network. RESULTS: Mortality was 32% in patients with cirrhosis compared to 8% in those without (p <0.001). Mortality in patients with cirrhosis increased according to Child-Pugh class (A [19%], B [35%], C [51%]) and the main cause of death was from respiratory failure (71%). After adjusting for baseline characteristics, factors associated with death in the total CLD cohort were age (odds ratio [OR] 1.02; 1.01-1.04), Child-Pugh A (OR 1.90; 1.03-3.52), B (OR 4.14; 2.4-7.65), or C (OR 9.32; 4.80-18.08) cirrhosis and alcohol-related liver disease (OR 1.79; 1.03-3.13). Compared to patients without CLD (n = 620), propensity-score-matched analysis revealed significant increases in mortality in those with Child-Pugh B (+20.0% [8.8%-31.3%]) and C (+38.1% [27.1%-49.2%]) cirrhosis. Acute hepatic decompensation occurred in 46% of patients with cirrhosis, of whom 21% had no respiratory symptoms. Half of those with hepatic decompensation had acute-on-chronic liver failure. CONCLUSIONS: In the largest such cohort to date, we demonstrate that baseline liver disease stage and alcohol-related liver disease are independent risk factors for death from COVID-19. These data have important implications for the risk stratification of patients with CLD across the globe during the COVID-19 pandemic. LAY SUMMARY: This international registry study demonstrates that patients with cirrhosis are at increased risk of death from COVID-19. Mortality from COVID-19 was particularly high among patients with more advanced cirrhosis and those with alcohol-related liver disease.

Predictors of Outcomes of COVID-19 in Patients With Chronic Liver Disease: US Multi-center Study.

BACKGROUND & AIMS: Chronic liver disease (CLD) represents a major global health burden. We undertook this study to identify the factors associated with adverse outcomes in patients with CLD who acquire the novel coronavirus-2019 (COVID-19). METHODS: We conducted a multi-center, observational cohort study across 21 institutions in the United States (US) of adult patients with CLD and laboratory-confirmed diagnosis of COVID-19 between March 1, 2020 and May 30, 2020. We performed survival analysis to identify independent predictors of all-cause mortality and COVID-19 related mortality, and multivariate logistic regression to determine the risk of severe COVID-19 in patients with CLD. RESULTS: Of the 978 patients in our cohort, 867 patients (mean age 56.9 ± 14.5 years, 55% male) met inclusion criteria. The overall all-cause mortality was 14.0% (n = 121), and 61.7% (n = 535) had severe COVID-19. Patients presenting with diarrhea or nausea/vomiting were more likely to have severe COVID-19. The liver-specific factors associated with independent risk of higher overall mortality were alcohol-related liver disease (ALD) (hazard ratio [HR] 2.42, 95% confidence interval [CI] 1.29-4.55), decompensated cirrhosis (HR 2.91 [1.70-5.00]) and hepatocellular carcinoma (HCC) (HR 3.31 [1.53-7.16]). Other factors were increasing age, diabetes, hypertension, chronic obstructive pulmonary disease and current smoker. Hispanic ethnicity (odds ratio [OR] 2.33 [1.47-3.70]) and decompensated cirrhosis (OR 2.50 [1.20-5.21]) were independently associated with risk for severe COVID-19. CONCLUSIONS: The risk factors which predict higher overall mortality among patients with CLD and COVID-19 are ALD, decompensated cirrhosis and HCC. Hispanic ethnicity and decompensated cirrhosis are associated with severe COVID-19. Our results will enable risk stratification and personalization of the management of patients with CLD and COVID-19. Clinicaltrials.gov number NCT04439084.

Potential Bias and Misconceptions in Liver Transplantation for Alcohol- and Obesity-Related Liver Disease.

INTRODUCTION: Bias and misconceptions surrounding alcohol-related liver disease (ALD) and obesity-related liver disease (OLD) may lead to transplant listing inequities. The aim of this study was to evaluate patients, medical students, residents, fellows, and attending physicians for bias and misconceptions regarding liver transplantation (LT) for patients with ALD and OLD. METHODS: Participants took a survey asking them whether patients with ALD who continue/discontinue drinking alcohol or patients with OLD who do/do not commit to a weight loss program deserve equal LT rights. A Likert scale was used for their responses. Participants also estimated 5-year survival and advanced fibrosis recurrence after LT. The primary outcome of the study was bias measured by expected agreement or disagreement to questions using a Likert scale, significant underestimation of a 5-year survival rate after LT, and significant overestimation of 5-year advanced fibrosis recurrence after LT. RESULTS: A total of 381 participants were included in the analysis: 153 residents/fellows, 31 attending physicians, 98 medical students, and 99 patients. A higher percentage from all 4 participating groups either were neutral or disagreed with equal LT rights for patients with ALD who discontinue drinking compared with patients with OLD who commit to weight loss program. The attending physician group was the only group with a majority estimating >60% 5-year survival after LT in patients with ALD and OLD (P < 0.05). All 4 groups had a majority estimate >20% 5-year advanced fibrosis recurrence in patients with ALD and OLD (P > 0.05). DISCUSSION: There seems to be current bias and misconceptions regarding LT for patients with ALD and OLD.

Individual liver plasmacytoid dendritic cells are capable of producing IFNα and multiple additional cytokines during chronic HCV infection.

Plasmacytoid dendritic cells (pDCs) are "natural" interferon α (IFNα)-producing cells. Despite their importance to antiviral defense, autoimmunity, and ischemic liver graft injury, because DC subsets are rare and heterogeneous, basic questions about liver pDC function and capacity to make cytokines remain unanswered. Previous investigations failed to consistently detect IFNα mRNA in HCV-infected livers, suggesting that pDCs may be incapable of producing IFNα. We used a combination of molecular, biochemical, cytometric, and high-dimensional techniques to analyze DC frequencies/functions in liver and peripheral blood mononuclear cells (PBMCs) of hepatitis C virus (HCV)-infected patients, to examine correlations between DC function and gene expression of matched whole liver tissue and liver mononuclear cells (LMCs), and to determine if pDCs can produce multiple cytokines. T cells often produce multiple cytokines/chemokines but until recently technical limitations have precluded tests of polyfunctionality in individual pDCs. Mass cytometry (CyTOF) revealed that liver pDCs are the only LMC that produces detectable amounts of IFNα in response TLR-7/8 stimulation. Liver pDCs secreted large quantities of IFNα (~2 million molecules of IFNα/cell/hour) and produced more IFNα than PBMCs after stimulation, p = 0.0001. LMCs secreted >14-fold more IFNα than IFNλ in 4 hours. Liver pDC frequency positively correlated with whole liver expression of "IFNα-response" pathway (R2 = 0.58, p = 0.007) and "monocyte surface" signature (R2 = 0.54, p = 0.01). Mass cytometry revealed that IFNα-producing pDCs were highly polyfunctional; >90% also made 2-4 additional cytokines/chemokines of our test set of 10. Liver BDCA1 DCs, but not BDCA3 DCs, were similarly polyfunctional. pDCs from a healthy liver were also polyfunctional. Our data show that liver pDCs retain the ability to make abundant IFNα during chronic HCV infection and produce many other immune modulators. Polyfunctional liver pDCs are likely to be key drivers of inflammation and immune activation during chronic HCV infection.

Liver Injury in Liver Transplant Recipients With Coronavirus Disease 2019 (COVID-19): U.S. Multicenter Experience.

BACKGROUND AND AIMS: Coronavirus disease 2019 (COVID-19) is associated with liver injury, but the prevalence and patterns of liver injury in liver transplantation (LT) recipients with COVID-19 are open for study. APPROACH AND RESULTS: We conducted a multicenter study in the United States of 112 adult LT recipients with COVID-19. Median age was 61 years (interquartile range, 20), 54.5% (n = 61) were male, and 39.3% (n = 44) Hispanic. Mortality rate was 22.3% (n = 25); 72.3% (n = 81) were hospitalized and 26.8% (n = 30) admitted to the intensive care unit (ICU). Analysis of peak values of alanine aminotransferase (ALT) during COVID-19 showed moderate liver injury (ALT 2-5× upper limit of normal [ULN]) in 22.2% (n = 18) and severe liver injury (ALT > 5× ULN) in 12.3% (n = 10). Compared to age- and sex-matched nontransplant patients with chronic liver disease and COVID-19 (n = 375), incidence of acute liver injury was lower in LT recipients (47.5% vs. 34.6%; P = 0.037). Variables associated with liver injury in LT recipients were younger age (P = 0.009; odds ratio [OR], 2.06; 95% confidence interval [CI], 1.20-3.54), Hispanic ethnicity (P = 0.011; OR, 6.01; 95% CI, 1.51-23.9), metabolic syndrome (P = 0.016; OR, 5.87; 95% CI, 1.38-24.99), vasopressor use (P = 0.018; OR, 7.34; 95% CI, 1.39-38.52), and antibiotic use (P = 0.046; OR, 6.93; 95% CI, 1.04-46.26). Reduction in immunosuppression (49.4%) was not associated with liver injury (P = 0.156) or mortality (P = 0.084). Liver injury during COVID-19 was significantly associated with mortality (P = 0.007; OR, 6.91; 95% CI, 1.68-28.48) and ICU admission (P = 0.007; OR, 7.93; 95% CI, 1.75-35.69) in LT recipients. CONCLUSIONS: Liver injury is associated with higher mortality and ICU admission in LT recipients with COVID-19. Hence, monitoring liver enzymes closely can help in early identification of patients at risk for adverse outcomes. Reduction of immunosuppression during COVID-19 did not increase risk for mortality or graft failure.

GM-CSF controls nonlymphoid tissue dendritic cell homeostasis but is dispensable for the differentiation of inflammatory dendritic cells.

GM-CSF (Csf-2) is a critical cytokine for the in vitro generation of dendritic cells (DCs) and is thought to control the development of inflammatory DCs and resident CD103(+) DCs in some tissues. Here we showed that in contrast to the current understanding, Csf-2 receptor acts in the steady state to promote the survival and homeostasis of nonlymphoid tissue-resident CD103(+) and CD11b(+) DCs. Absence of Csf-2 receptor on lung DCs abrogated the induction of CD8(+) T cell immunity after immunization with particulate antigens. In contrast, Csf-2 receptor was dispensable for the differentiation and innate function of inflammatory DCs during acute injuries. Instead, inflammatory DCs required Csf-1 receptor for their development. Thus, Csf-2 is important in vaccine-induced CD8(+) T cell immunity through the regulation of nonlymphoid tissue DC homeostasis rather than control of inflammatory DCs in vivo.

Recipient risk factors for acute cellular rejection after orthotopic liver transplant - a single-center, retrospective study.

The use of model for end-stage liver disease (MELD) score for liver allocation has resulted in transplanting sicker patients. As such, it is unclear whether the risk factors and severity of acute cellular rejection (ACR) have changed. To identify ACR characteristics where average MELD score at transplant is higher than previously published studies. This is a single-center, retrospective study designed to assess risk factors associated with ACR after adult orthotopic liver transplant (OLT) using a steroid sparing regimen. This study included 174 OLT patients transplanted from 2008 to 2013 at a single tertiary care center. Recipient demographics, preoperative clinical, and laboratory data were recorded for each transplant. Univariate and multivariate regression analyses were performed to identify variables that are significant predictors for ACR. The median MELD at transplantation was 29.5. The average time from transplant to ACR diagnosis was 283.9 days and a majority of ACR episodes were mild to moderate. Serum creatinine, primary sclerosing cholangitis etiology, and tacrolimus use were significant predictors for ACR (P < 0.05). This study confirmed a change in timing and severity of ACR in the MELD era. Recipient characteristics may affect the risk for developing ACR and should be considered when managing immunosuppression.

Diurnal variations in intestinal barrier integrity and liver pathology in mice: implications for alcohol binge.

Recent studies suggest that circadian rhythms regulate intestinal barrier integrity, but it is not clear whether there are daily variations in barrier integrity. This study investigated daily variations in intestinal barrier integrity, including whether there are differences in alcohol-induced intestinal barrier dysfunction after an alcohol binge at different times of day and whether this is associated with concurrent liver injury. C57BL6/J male mice were fed a standard chow diet, an alcohol-containing liquid diet, or an alcohol control diet for 4 wk. During week 5 (i.e., on days 43-45), mice received three once-daily gavages of alcohol (6 g/kg) or the control (phosphate-buffered saline) at the same time each day. Immediately after the binge on the second day, intestinal permeability was assessed. Four hours after the third and final binge, mice were euthanized and tissue samples collected. The results demonstrated diet-specific and outcome-specific effects of time, alcohol, and/or time by alcohol interaction. Specifically, the alcohol binge robustly influenced markers of intestinal barrier integrity, and liver markers were robustly influenced by time of day. Only intestinal permeability (i.e., sucralose) demonstrated a significant effect of time and also showed a binge by time interaction, suggesting that the time of the alcohol binge influences colonic permeability. NEW & NOTEWORTHY This study investigated daily variations in intestinal barrier integrity, including whether there are differences in alcohol-induced intestinal barrier dysfunction after an alcohol binge at different times of day and whether this is associated with concurrent liver injury. We conclude that 1) alcohol binge significantly impacted markers of intestinal permeability, 2) time of day significantly affected liver outcomes, and 3) the time of day influenced colonic permeability.

Overactivation of intestinal sterol response element-binding protein 2 promotes diet-induced nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD) is characterized by lipid accumulation in the liver that may progress to hepatic fibrosis and nonalcoholic steatohepatitis (NASH). Mechanisms underlying NAFLD and NASH are not yet fully understood. Dietary cholesterol was recently shown to be a risk factor for the development of NASH, suggesting a role for intestinal handling of cholesterol. One important regulator of cholesterol homeostasis is the sterol response element-binding protein-2 (SREBP-2) transcription factor. We tested the hypothesis that the overactivation of intestinal SREBP-2 increases the susceptibility to diet-induced NASH. A transgenic mouse model with intestine-specific overexpression of active SREBP-2 (ISR2 mice) driven by villin promoter was used. ISR2 mice and their wild-type littermates were fed a regular chow diet or a high-fat, high-cholesterol (HFHC) diet (15% fat, 1% cholesterol) for 15 wk. Results showed that HFHC feeding to ISR2 mice caused hepatic inflammation with increased levels of proinflammatory cytokines. Histological examination demonstrated extensive fibrosis after a HFHC diet associated with a perivascular as well as pericellular collagen deposits in ISR2 mice compared with wild-type littermates. The severe hepatic inflammation and advanced fibrosis in ISR2 mice was not associated with a difference in lipid accumulation in ISR2 mice compared with wild type littermates after HFHC feeding. These data indicate that overactivation of intestinal SREBP2 promotes diet-induced hepatic inflammation with features of human NASH resulting in rapid severe fibrosis and provide a novel link between regulatory processes of intestinal cholesterol and progression of fatty liver.NEW & NOTEWORTHY The current study highlights the role of overactivation of intestinal SREBP-2 transcription factor in the progression of hepatic fibrosis associated with diet-induced NASH. Mice with intestine-specific overexpression of SREBP-2 demonstrated more inflammation and severe fibrosis in the liver in response to 15 wk of being fed a high-cholesterol, high-fat diet as compared with their wild-type littermates. These data demonstrate a novel link between intestinal regulatory processes of cholesterol metabolism and the pathogenesis of fatty liver diseases.

Interleukin-15 receptor α on hepatic stellate cells regulates hepatic fibrogenesis in mice.

BACKGROUND & AIMS: Interleukin-15 (IL-15) and its high affinity receptor interleukin-15 receptor alpha (IL-15Rα) are widely expressed in immune cells and hepatic resident cells. IL-15 signaling has important functions in homeostasis of natural killer (NK), natural killer T (NKT) and cytotoxic T (CD8(+) T) cells, and in liver regeneration. We hypothesized that IL-15 has a protective role in liver fibrosis progression by maintaining NK cell homeostasis. METHODS: Fibrosis was induced using two mechanistically distinct models. Congenic bone marrow transplantation was used to evaluate the contribution of IL-15 signaling from various compartments to NK, CD8(+) T and NKT cell homeostasis and fibrogenesis. The gene expression profile of hepatic stellate cell (HSC) from IL-15Rα knockout (IL-15RαKO) mice and wild-type mice were captured using microarray analysis and validated in isolated HSC. Quantitative real-time PCR was used to assess repressors of collagen transcription. RESULTS: IL-15RαKO mice exhibited more fibrosis in both models. IL-15 signaling from specific types of hepatic cells had divergent roles in maintaining liver NK, CD8(+) T and NKT cells, with a direct and protective role on radio-resistant non-parenchymal cells beyond the control of NK homeostasis. HSCs isolated from IL-15RαKO mice demonstrated upregulation of collagen production. Finally, IL-15RαKO HSC with or without transforming growth factor beta (TGF-ß) stimulation exhibited increased expression of fibrosis markers and decreased collagen transcription repressors expression. CONCLUSIONS: IL-15Rα signaling has a direct anti-fibrotic effect independent of preserving NK homeostasis. These findings establish a rationale to further explore the anti-fibrotic potential of enhancing IL-15 signaling in HSCs. LAY SUMMARY: We investigated how a cellular protein, Interleukin-15 (IL-15), decreases the amount of scar tissue that is formed upon liver injury. We found that IL-15 and its receptor decrease the amount of scar tissue that is created by specialized liver cells (called stellate cells) and increase the number of a specific subgroup of immune cells (natural killer cells) that are known to eliminate stellate cells. TRANSCRIPT PROFILING ACCESSION NUMBER: GSE45612, GSE 68001 and GSE 25097.

Increased hepatic progenitor cell response and ductular reaction in patients with severe recurrent HCV post-liver transplantation.

OBJECTIVES: Post-liver transplant (LT) hepatitis C virus (HCV) patients may develop allograft cirrhosis and rarely fibrosing cholestatic hepatitis (FCH), while others have a stable course. Hepatic progenitor cells (HPC) may be implicated in liver injury and fibrogenesis through ductular reaction (DR). We studied HPC response and DR in three distinct post-LT patterns of HCV: stable recurrence, allograft cirrhosis, and FCH. METHODS: We identified 52 patients with untreated recurrent HCV and longitudinal liver biopsies (20 stable/23 cirrhosis/9 FCH) and eight healthy controls. Archived liver biopsy specimens for three time points (LT; initial recurrence; and clinical outcome) were stained for cytokeratin-7. Manual HPC counts and DR quantification using image analysis were performed. RESULTS: HCV counts and DR at LT did not differ across groups. At initial recurrence, HPC expansion occurred only in patients who developed cirrhosis, while prominent DR was present in those who developed FCH vs. stable and controls (p < 0.05). At outcome biopsies, HPC response and DR were increased in cirrhosis and FCH vs. stable and controls (p < 0.05). HPC response and DR did not differ in stable vs. CONCLUSIONS: These findings suggest that an altered HPC response assessed by cytokeratin-7 stain after LT may predict severity of HCV recurrence.

The dynamic and clinical significance of autoantibodies and immunoglobulins in liver transplant recipients.

Little is known about autoantibody pattern in liver transplantation (LT). The aim of the study was to examine autoantibodies (AAB) and immunoglobulins in patients with end-stage liver disease before and after LT. Patients with LT who underwent post-LT biopsies between 10/2008 and 8/2011 were enrolled. AAB were assessed at the time of LT and liver biopsy. Demographics, serum immunoglobulins, AAB, and liver histology (explant, post-LT biopsies) were analyzed. Two hundred and twenty patients (M/F 143/77; age at LT 54 (19-73)) were included; AAB and immunoglobulins were evaluated in 76 patients. Length of follow-up from LT was 285 (30-1462) days. Sixty-one percent of patients had hepatitis C (HCV); 83% developed recurrent HCV. A significant decrease in IgG, IgA, IgM (p < 0.001 each), anticardiolipin antibodies IgG and IgM (p = 0.02), and beta-2 microglobulin (p = 0.004) was observed post-LT. HCV patients had higher IgG (p = 0.005), rheumatoid factor (p = 0.044) before LT; elevated IgM was associated with increased inflammation in the explant (p = 0.007). Lower IgG levels and antismooth muscle antibodies were present before LT in a higher percentage in patients who would develop recurrent HCV (p = 0.004, p = 0.077, respectively). In conclusion, AAB change significantly after LT and have a different pattern in HCV. Some immunological markers are associated with HCV recurrence and advanced inflammation on explant.

Central role of conventional dendritic cells in regulation of bone marrow release and survival of neutrophils.

Neutrophils are the most abundant cell type in the immune system and play an important role in the innate immune response. Using a diverse range of mouse models with either defective dendritic cell (DC) development or conditional DC depletion, we provide in vivo evidence indicating that conventional DCs play an important role in the regulation of neutrophil homeostasis. Flk2, Flt3L, and Batf3 knockout mice, which have defects in DC development, have increased numbers of liver neutrophils in the steady state. Conversely, neutrophil frequency is reduced in DC-specific PTEN knockout mice, which have an expansion of CD8(+) and CD103(+) DCs. In chimeric CD11c-DTR mice, conventional DC depletion results in a systemic increase of neutrophils in peripheral organs in the absence of histological inflammation or an increase in proinflammatory cytokines. This effect is also present in splenectomized chimeric CD11c-DTR mice and is absent in chimeric mice with 50% normal bone marrow. In chimeric CD11c-DTR mice, diphtheria toxin treatment results in enhanced neutrophil trafficking from the bone marrow into circulation and increased neutrophil recruitment. Moreover, there is an increased expression of chemokines/cytokines involved in neutrophil homeostasis and reduced neutrophil apoptosis. These data underscore the role of the DC pool in regulating the neutrophil compartment in nonlymphoid organs.

ß-PDGF receptor expressed by hepatic stellate cells regulates fibrosis in murine liver injury, but not carcinogenesis.

BACKGROUND & AIMS: Rapid induction of ß-PDGF receptor (ß-PDGFR) is a core feature of hepatic stellate cell activation, but its cellular impact in vivo is not well characterized. We explored the contribution of ß-PDGFR-mediated pathway activation to hepatic stellate cell responses in liver injury, fibrogenesis, and carcinogenesis in vivo using genetic models with divergent ß-PDGFR activity, and assessed its prognostic implications in human cirrhosis. METHODS: The impact of either loss or constitutive activation of ß-PDGFR in stellate cells on fibrosis was assessed following carbon tetrachloride (CCl4) or bile duct ligation. Hepatocarcinogenesis in fibrotic liver was tracked after a single dose of diethylnitrosamine (DEN) followed by repeated injections of CCl4. Genome-wide expression profiling was performed from isolated stellate cells that expressed or lacked ß-PDGFR to determine deregulated pathways and evaluate their association with prognostic gene signatures in human cirrhosis. RESULTS: Depletion of ß-PDGFR in hepatic stellate cells decreased injury and fibrosis in vivo, while its auto-activation accelerated fibrosis. However, there was no difference in development of DEN-induced pre-neoplastic foci. Genomic profiling revealed ERK, AKT, and NF-κB pathways and a subset of a previously identified 186-gene prognostic signature in hepatitis C virus (HCV)-related cirrhosis as downstream of ß-PDGFR in stellate cells. In the human cohort, the ß-PDGFR signature was not associated with HCC development, but was significantly associated with a poorer outcome in HCV cirrhosis. CONCLUSIONS: ß-PDGFR is a key mediator of hepatic injury and fibrogenesis in vivo and contributes to the poor prognosis of human cirrhosis, but not by increasing HCC development.

Inhibition of the CXCL12/CXCR4 chemokine axis with AMD3100, a CXCR4 small molecule inhibitor, worsens murine hepatic injury.

AIM: Activation of hepatic stellate cells and development of chronic inflammation are two key features in the progression of hepatic fibrosis. We have shown that in vitro activated stellate cells increase their expression of CXCL12 as well as the receptor CXCR4 and that receptor engagement promotes a profibrogenic phenotype. Furthermore, injury promotes increased hepatic expression of CXCL12 and a massive infiltration of CXCR4-expressing leukocytes, granulocytes and myeloid cells. The primary site of inflammatory cell accumulation is around the CXCL12-rich portal tracts and within fibrotic septae, indicating a role for CXCR4 during injury. In order to characterize the relevance of the CXCR4/CXCL12 chemokine axis during hepatic injury we inhibited the axis using AMD3100, a CXCR4 small molecule inhibitor, in models of chronic and acute liver injury. METHODS: Mice were subjected to acute and chronic CCl4 liver injury with and without AMD3100 administration. The degree of liver injury, fibrosis and the composition of the intrahepatic inflammatory response were characterized. RESULTS: Treatment of mice with AMD3100 in the chronic CCl4 model of liver injury led to an increase in hepatic inflammation and fibrosis with a specific increase in intrahepatic neutrophils. Furthermore, in an acute model of CCl4 -induced liver injury, AMD3100 led to an increase in the number of intrahepatic neutrophils and a trend towards worse necrosis. CONCLUSION: Together, this data suggests that inhibition of the CXCR4/CXCL12 chemokine axis is injurious through modulation of the hepatic inflammatory response and that this axis may serve a protective role in liver injury.

Dendritic cells and liver fibrosis.

Dendritic cells are a relative rare population of specialized antigen presenting cells that are distributed through most lymphoid and non-lymphoid tissues and play a critical role in linking the innate and adaptive arms of the immune system. The liver contains a heterogeneous population of dendritic cells that may contribute to liver inflammation and fibrosis through a number of mechanisms. This review summarizes current knowledge on the development and characterization of liver dendritic cells and their potential impact on liver fibrosis. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.