Source and characterization of hepatic macrophages in acetaminophen-induced acute liver failure in humans

Acetaminophen-induced acute liver failure (AALF) is associated with innate immunity activation, which contributes to the severity of hepatic injury and clinical outcome. A marked increase in hepatic macrophages (h-mφ) is observed in experimental models of AALF, but controversy exists regarding their role, implicating h-mφ in both aggravation and resolution of liver injury. The role of h-mφ in human AALF is virtually unexplored. We sought to investigate the role of chemokine (C-C motif) ligand 2 (CCL2) in the recruitment of circulating monocytes to the inflamed liver and to determine how the h-mφ infiltrate and liver microenvironment may contribute to tissue repair versus inflammation in AALF. We evaluated circulating monocytes, their chemokine (C-C motif) receptor 2 (CCR2) expression, and serum CCL2 levels in patients with AALF. Cell subsets and numbers of circulation-derived (MAC387+) or resident proliferating (CD68/Ki67+) h-mφ in hepatic immune infiltrates were determined by immunohistochemistry. Inflammatory cytokine levels were determined in whole and laser microdissected liver tissue by proteome array. In AALF, circulating monocytes were depleted, with the lowest levels observed in patients with adverse outcomes. CCL2 levels were high in AALF serum and hepatic tissue, and circulating monocyte subsets expressed CCR2, suggesting CCL2-dependent hepatic monocyte recruitment. Significant numbers of both MAC387+ and CD68+ h-mφ were found in AALF compared with control liver tissue with a high proportion expressing the proliferation marker Ki67. Levels of CCL2, CCL3, interleukin (IL)-6, IL-10, and transforming growth factor-β1 were significantly elevated in AALF liver tissue relative to chronic liver disease controls.

CONCLUSION

In AALF, the h-mφ population is expanded in areas of necrosis, both through proliferation of resident cells and CCL2-dependent recruitment of circulating monocytes. The presence of h-mφ within an anti-inflammatory/regenerative microenvironment indicates that they are implicated in resolution of inflammation/tissue repair processes during AALF.

Infection and systemic inflammation, not ammonia, are associated with Grade 3/4 hepatic encephalopathy, but not mortality in cirrhosis

BACKGROUND & AIMS

Patients with cirrhosis are prone to infection which is a frequent precipitant of hepatic encephalopathy (HE). Clinical studies have examined the importance of inflammation and infection in modulating the manifestation of symptoms of HE in acute liver failure and patients with cirrhosis and minimal/low grade HE. It would be logical to presume that this relationship persists in patients who develop severe HE in cirrhosis although this has not been examined to date.

METHODS

We report the findings of a prospective audit of 100 consecutive patients with cirrhosis admitted between Jan 2000 and March 2008 to a liver Intensive Care Unit (ICU) where HE was the primary indication for admission (59% Grade 3; 41% Grade 4). Haematological and microbiological data were collected at ICU admission, and organ scores and outcomes were recorded.

RESULTS

46% of patients had positive cultures taken within ± 48h from admission to ICU [25% blood] and a further 22% were culture negative but had evidence of systemic inflammation (SIRS). SIRS score (p=0.03) and SOFA score (p=0.006) were significantly higher in those patients with Grade 4 HE, who were also less likely to survive (p<0.001). HE grade/coma score did not correlate with ammonia, biochemistry or MELD score. Fifty-two percent of patients survived their ICU stay while the remainder developed progressive multiorgan failure and died; 38% survived to discharge, and 16% were transplanted.

CONCLUSIONS

These data support an association between infection/SIRS and not ammonia, in patients with cirrhosis that develop severe HE. The presence or absence of infection/SIRS did not determine survival.

MerTK expressing hepatic macrophages promote the resolution of inflammation in acute liver failure

OBJECTIVE

Acute liver failure (ALF) is characterised by overwhelming hepatocyte death and liver inflammation with massive infiltration of myeloid cells in necrotic areas. The mechanisms underlying resolution of acute hepatic inflammation are largely unknown. Here, we aimed to investigate the impact of Mer tyrosine kinase (MerTK) during ALF and also examine how the microenvironmental mediator, secretory leucocyte protease inhibitor (SLPI), governs this response.

DESIGN

Flow cytometry, immunohistochemistry, confocal imaging and gene expression analyses determined the phenotype, functional/transcriptomic profile and tissue topography of MerTK+ monocytes/macrophages in ALF, healthy and disease controls. The temporal evolution of macrophage MerTK expression and its impact on resolution was examined in APAP-induced acute liver injury using wild-type (WT) and Mer-deficient (Mer^-/-) mice. SLPI effects on hepatic myeloid cells were determined in vitro and in vivo using APAP-treated WT mice.

RESULTS

We demonstrate a significant expansion of resolution-like MerTK+HLA-DR^high cells in circulatory and tissue compartments of patients with ALF. Compared with WT mice which show an increase of MerTK+MHCII^high macrophages during the resolution phase in ALF, APAP-treated Mer^-/- mice exhibit persistent liver injury and inflammation, characterised by a decreased proportion of resident Kupffer cells and increased number of neutrophils. Both in vitro and in APAP-treated mice, SLPI reprogrammes myeloid cells towards resolution responses through induction of a MerTK+HLA-DR^high phenotype which promotes neutrophil apoptosis and their subsequent clearance.

CONCLUSIONS

We identify a hepatoprotective, MerTK+, macrophage phenotype that evolves during the resolution phase following ALF and represents a novel immunotherapeutic target to promote resolution responses following acute liver injury.

Secretory leukocyte protease inhibitor: a pivotal mediator of anti-inflammatory responses in acetaminophen-induced acute liver failure

Acetaminophen-induced acute liver failure (AALF) is characterized both by activation of innate immune responses and susceptibility to sepsis. Circulating monocytes and hepatic macrophages are central mediators of inflammatory responses and tissue repair processes during human AALF. Secretory leukocyte protease inhibitor (SLPI) modulates monocyte/macrophage function through inhibition of nuclear factor kappa B (NF-κB) signaling. The aims of this study were to establish the role of SLPI in AALF. Circulating levels of SLPI, monocyte cluster of differentiation 163 (CD163), human leukocyte antigen-DR (HLA-DR), and lipopolysaccharide (LPS)-stimulated levels of NF-κBp65, tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 were determined in patients with AALF, chronic liver disease, and healthy controls. Immunohistochemistry and multispectral imaging of AALF explant tissue determined the cellular sources of SLPI and hepatic macrophage phenotype. The phenotype and function of monocytes and macrophages was determined following culture with recombinant human (rh)-SLPI, liver homogenates, and plasma derived from AALF patients in the presence and absence of antihuman (α)SLPI. Hepatic and circulatory concentrations of SLPI were elevated in AALF and immunohistochemistry revealed SLPI expression in biliary epithelial cells and within hepatic macrophages (h-mψ) in areas of necrosis. H-mψ and circulating monocytes in AALF exhibited an anti-inflammatory phenotype and functional characteristics; typified by reductions in NF-κBp65, TNF-α, and IL-6 and preserved IL-10 secretion following LPS challenge. Culture of healthy monocytes with AALF liver homogenates, plasma, or rhSLPI induced monocytes with strikingly similar anti-inflammatory characteristics which were reversed by inhibiting the activity of SLPI.

CONCLUSION

SLPI is a pivotal mediator of anti-inflammatory responses in AALF through modulation of monocyte/macrophage function, which may account for the susceptibility to sepsis in AALF.

Multivariate metabotyping of plasma predicts survival in patients with decompensated cirrhosis

BACKGROUND & AIMS

Predicting survival in decompensated cirrhosis (DC) is important in decision making for liver transplantation and resource allocation. We investigated whether high-resolution metabolic profiling can determine a metabolic phenotype associated with 90-day survival.

METHODS

Two hundred and forty-eight subjects underwent plasma metabotyping by (1)H nuclear magnetic resonance (NMR) spectroscopy and reversed-phase ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry (UPLC-TOF-MS; DC: 80-derivation set, 101-validation; stable cirrhosis (CLD) 20 and 47 healthy controls (HC)).

RESULTS

(1)H NMR metabotyping accurately discriminated between surviving and non-surviving patients with DC. The NMR plasma profiles of non-survivors were attributed to reduced phosphatidylcholines and lipid resonances, with increased lactate, tyrosine, methionine and phenylalanine signal intensities. This was confirmed on external validation (area under the receiver operating curve [AUROC]=0.96 (95% CI 0.90-1.00, sensitivity 98%, specificity 89%). UPLC-TOF-MS confirmed that lysophosphatidylcholines and phosphatidylcholines [LPC/PC] were downregulated in non-survivors (UPLC-TOF-MS profiles AUROC of 0.94 (95% CI 0.89-0.98, sensitivity 100%, specificity 85% [positive ion detection])). LPC concentrations negatively correlated with circulating markers of cell death (M30 and M65) levels in DC. Histological examination of liver tissue from DC patients confirmed increased hepatocyte cell death compared to controls. Cross liver sampling at time of liver transplantation demonstrated that hepatic endothelial beds are a source of increased circulating total cytokeratin-18 in DC.

CONCLUSION

Plasma metabotyping accurately predicts mortality in DC. LPC and amino acid dysregulation is associated with increased mortality and severity of disease reflecting hepatocyte cell death.

The severity of circulating neutrophil dysfunction in patients with cirrhosis is associated with 90-day and 1-year mortality

BACKGROUND

Patients with cirrhosis are susceptible to sepsis, pre-disposing to the development of encephalopathy, bleeding and organ dysfunction with associated high mortality.

AIM

To characterise circulating neutrophil function in a cirrhotic cohort as a determinant of 90-day and 1-year mortality.

METHODS

Sixty-two patients with cirrhosis [49 stable (Child-Pugh A/B/C = 24%/39%/37%); 13 acute-on-chronic liver failure] were prospectively studied and compared with 11 healthy controls. Neutrophil function was evaluated at baseline and repeated at critical points during the course of the patient's illness until death/transplantation. Neutrophil phenotype was determined using fluorochrome-labelled antibodies to CD16/CD11b and assessed by flow cytometry. Neutrophil phagocytic activity (NPA) and capacity (NPC) were determined using FITC-labelled opsonised Escherichia coli. Oxidative burst (OB) was quantified by the percentage of neutrophils producing reactive oxygen species (ROS) and mean fluorescence intensity at rest, and after stimulation with E. coli. Physiological variables, biochemistry, microbiology and outcomes were collected. Plasma pro- and anti-inflammatory cytokine profiles were performed by ELISA.

RESULTS

NPA/NPC was impaired in cirrhosis with the most significant dysfunction being observed in those with advanced disease and in those treated with propranolol. NPC predicted survival in stable cirrhosis [AUROC 0.83 (95% CI 0.68-0.97); P = 0.021] and differentiated survivors from nonsurvivors (90-day P = 0.01; 1 year P < 0.001). Resting OB ≥12% predicted 90-day mortality with 80% sensitivity and 71% specificity [AUROC 0.81 (95% CI 0.64-0.97); P = 0.026 and differentiated survivors from nonsurvivors; P = 0.015].

CONCLUSION

Circulating neutrophils in patients with cirrhosis are dysfunctional and predict the development of infection, organ dysfunction and survival at 90 days and 1 year.

3-Deoxy-D-manno-octulosonate-8-phosphate synthase catalyzes the C-O bond cleavage of phosphoenolpyruvate

The mechanism of 3-deoxy-D-manno-octulosonate-8-phosphate (KDO8P) synthase was investigated. When [18O]-PEP specifically labeled in the enolic oxygen is a substrate for KDO8P synthase, the 18O is recovered in Pi. This indicates that the KDO8P synthase reaction proceeds with C-O bond cleavage of PEP similar to that observed in the 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase catalyzed condensation of PEP and erythrose-4-phosphate (1). No evidence for a covalent enzyme-PEP intermediate could be obtained. No [32P]-Pi exchange into PEP nor scrambling of bridge 18O to non-bridging positions in [18O]-PEP was observed in the presence or absence of arabinose-5-phosphate or its analog ribose-5-phosphate. Bromopyruvate inactivated KDO8P synthase in a time dependent process. It is likely that bromopyruvate reacts with a functional group at the PEP binding site since PEP, but not arabinose-5-phosphate, protects against inactivation.

Defective monocyte oxidative burst predicts infection in alcoholic hepatitis and is associated with reduced expression of NADPH oxidase

OBJECTIVE

In order to explain the increased susceptibility to serious infection in alcoholic hepatitis, we evaluated monocyte phagocytosis, aberrations of associated signalling pathways and their reversibility, and whether phagocytic defects could predict subsequent infection.

DESIGN

Monocytes were identified from blood samples of 42 patients with severe alcoholic hepatitis using monoclonal antibody to CD14. Phagocytosis and monocyte oxidative burst (MOB) were measured ex vivo using flow cytometry, luminometry and bacterial killing assays. Defects were related to the subsequent development of infection. Intracellular signalling pathways were investigated using western blotting and PCR. Interferon-γ (IFN-γ) was evaluated for its therapeutic potential in reversing phagocytic defects. Paired longitudinal samples were used to evaluate the effect of in vivo prednisolone therapy.

RESULTS

MOB, production of superoxide and bacterial killing in response to Escherichia coli were markedly impaired in patients with alcoholic hepatitis. Pretreatment MOB predicted development of infection within two weeks with sensitivity and specificity that were superior to available clinical markers. Accordingly, defective MOB was associated with death at 28 and 90 days. Expression of the gp91 ^phox subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was reduced in patients with alcoholic hepatitis demonstrating defective MOB. Monocytes were refractory to IFN-γ stimulation and showed high levels of a negative regulator of cytokine signalling, suppressor of cytokine signalling-1. MOB was unaffected by 7 days in vivo prednisolone therapy.

CONCLUSIONS

Monocyte oxidative burst and bacterial killing is impaired in alcoholic hepatitis while bacterial uptake by phagocytosis is preserved. Defective MOB is associated with reduced expression of NADPH oxidase in these patients and predicts the development of infection and death.

Increased Expression of Cytotoxic T-Lymphocyte-Associated Protein 4 by T Cells, Induced by B7 in Sera, Reduces Adaptive Immunity in Patients With Acute Liver Failure

BACKGROUND & AIMS

Patients with acute liver failure (ALF) have defects in innate immune responses to microbes (immune paresis) and are susceptible to sepsis. Cytotoxic T-lymphocyte-associated protein 4 (CTLA4), which interacts with the membrane receptor B7 (also called CD80 and CD86), is a negative regulator of T-cell activation. We collected T cells from patients with ALF and investigated whether inhibitory signals down-regulate adaptive immune responses in patients with ALF.

METHODS

We collected peripheral blood mononuclear cells from patients with ALF and controls from September 2013 through September 2015 (45 patients with ALF, 20 patients with acute-on-chronic liver failure, 15 patients with cirrhosis with no evidence of acute decompensation, 20 patients with septic shock but no cirrhosis or liver disease, and 20 healthy individuals). Circulating CD4⁺ T cells were isolated and analyzed by flow cytometry. CD4⁺ T cells were incubated with antigen, or agonist to CD3 and dendritic cells, with or without antibody against CTLA4; T-cell proliferation and protein expression were quantified. We measured levels of soluble B7 molecules in supernatants of isolated primary hepatocytes, hepatic sinusoidal endothelial cells, and biliary epithelial cells from healthy or diseased liver tissues. We also measured levels of soluble B7 serum samples from patients and controls, and mice with acetaminophen-induced liver injury using enzyme-linked immunosorbent assays.

RESULTS

Peripheral blood samples from patients with ALF had a higher proportion of CD4⁺ CTLA4⁺ T cells than controls; patients with infections had the highest proportions. CD4⁺ T cells from patients with ALF had a reduced proliferative response to antigen or CD3 stimulation compared to cells from controls; incubation of CD4⁺ T cells from patients with ALF with an antibody against CTLA4 increased their proliferative response to antigen and to CD3 stimulation, to the same levels as cells from controls. CD4⁺ T cells from controls up-regulated expression of CTLA4 after 24-48 hours culture with sera from patients with ALF; these sera were found to have increased concentrations of soluble B7 compared to sera from controls. Necrotic human primary hepatocytes exposed to acetaminophen, but not hepatic sinusoidal endothelial cells and biliary epithelial cells from patients with ALF, secreted high levels of soluble B7. Sera from mice with acetaminophen-induced liver injury contained high levels of soluble B7 compared to sera from mice without liver injury. Plasma exchange reduced circulating levels of soluble B7 in patients with ALF and expression of CTLA4 on T cells.

CONCLUSIONS

Peripheral CD4⁺ T cells from patients with ALF have increased expression of CTLA4 compared to individuals without ALF; these cells have a reduced response to antigen and CD3 stimulation. We found sera of patients with ALF and from mice with liver injury to have high concentrations of soluble B7, which up-regulates CTLA4 expression by T cells and reduces their response to antigen. Plasma exchange reduces levels of B7 in sera from patients with ALF and might be used to restore antimicrobial responses to patients.

Derivation and validation of a cardiovascular risk score for prediction of major acute cardiovascular events in non-alcoholic fatty liver disease; the importance of an elevated mean platelet volume

BACKGROUND

Atherosclerotic cardiovascular disease is a key cause of morbidity in non-alcoholic fatty liver disease (NAFLD) but appropriate means to predict major acute cardiovascular events (MACE) are lacking.

AIM

To design a bespoke cardiovascular risk score in NAFLD.

METHODS

A retrospective derivation (2008-2016, 356 patients) and a prospective validation (2016- 2017, 111 patients) NAFLD cohort study was performed. Clinical and biochemical data were recorded at enrolment and mean platelet volume (MPV), Qrisk2 and Framingham scores were recorded one year prior to MACE (Cardiovascular death, acute coronary syndrome, stroke and transient ischaemic attack).

RESULTS

The derivation and validation cohorts were well-matched, with MACE prevalence 12.6% and 12%, respectively. On univariate analysis, age, diabetes, advanced fibrosis, collagen proportionate area >5%, MPV and liver stiffness were associated with MACE. After multivariate analysis, age, diabetes and MPV remained independently predictive of MACE. The "NAFLD CV-risk score" was generated using binary logistic regression: 0.06*(Age) + 0.963*(MPV) + 0.26*(DM¹ ) - 16.44; ¹ Diabetes mellitus: 1: present; 2: absent. (AUROC 0.84). A cut-off of -3.98 gave a sensitivity 97%, specificity 27%, PPV 16%, and NPV 99%. An MPV alone of >10.05 gave a sensitivity 97%, specificity 59%, PPV 24% and NPV 97% (AUROC 0.83). Validation cohort AUROCs were comparable at 0.77 (NAFLD CV-risk) and 0.72 (MPV). In the full cohort, the NAFLD CV-risk score and MPV outperformed both Qrisk2 and Framingham scores.

CONCLUSIONS

The NAFLD CV risk score and MPV accurately predict 1-year risk of MACE, thereby allowing better identification of patients that require optimisation of their cardiovascular risk profile.

Windows to the self in 8-year-olds: bridges to attachment representation and behavioral adjustment

The present study investigated the links between aspects of the self (self-evaluations, self-worth), attachment representations and behavioral functioning in 8-year-old children. Self-evaluations were assessed with an interview in which children described themselves and discussed positive and negative aspects of the self; self-worth was assessed using a subscale from the Dimensions of Depression Inventory. Attachment representations were assessed using the Separation Anxiety Test. Mothers and teachers reported on children's behavior problems, school adaptation and peer competence. Following previous work with 5- (Verschueren & Marcoen, 1999; Verschueren, Marcoen, & Schoefs, 1996) and 6-year-olds (Cassidy, 1988), we predicted that aspects of the self would be positively associated with attachment security and behavioral adaptation. These predictions were confirmed. A rating of the child's ease of access to self-evaluations (EASE) during the interview was related to emotional security and coping responses during the Separation Anxiety Test. Children with greater ease of access to self-evaluations also had fewer internalizing and total behavior problems, according to both mothers and teachers, and their teachers reported more positive school adaptation, peer competence and egoresiliency.

Immunopathogenesis of primary biliary cirrhosis: an old wives' tale

Primary biliary cirrhosis (PBC) is a cholestatic liver disease characterised by the autoimmune destruction of the small intrahepatic bile ducts. The disease has an unpredictable clinical course, but may progress to fibrosis and cirrhosis. Although medical treatment with urseodeoxycholic acid is largely successful, some patients may progress to liver failure requiring liver transplantation. PBC is characterised by the presence of disease specific anti-mitochondrial (AMA) antibodies, which are pathognomonic for PBC development. The disease demonstrates an overwhelming female preponderance and virtually all women with PBC present in middle age. The reasons for this are unknown; however several environmental and immunological factors may be involved. As the immune systems ages, it become less self tolerant, and mounts a weaker response to pathogens, possibly leading to cross reactivity or molecular mimicry. Some individuals display immunological changes which encourage the development of autoimmune disease. Risk factors implicated in PBC include recurrent urinary tract infection in females, as well as an increased prevalence of reproductive complications. These risk factors may work in concert with and possibly even accelerate, immune system ageing, contributing to PBC development. This review will examine the changes that occur in the immune system with ageing, paying particular attention to those changes which contribute to the development of autoimmune disease with increasing age. The review also discusses risk factors which may account for the increased female predominance of PBC, such as recurrent UTI and oestrogens.

Comparison of scoring systems and outcome of patients admitted to a liver intensive care unit of a tertiary referral centre with severe variceal bleeding

BACKGROUND

Acute variceal haemorrhage (AVH) is associated with significant mortality.

AIMS

To determine outcome and factors associated with hospital mortality (HM) in patients with AVH admitted to intensive care unit (ICU) and to compare outcomes of patients requiring transfer to a tertiary ICU (transfer group, TG) to a local in-patient group (LG).

METHODS

A retrospective study of all adult patients (N = 177) admitted to ICU with AVH from 2000-2008 was performed.

RESULTS

Median age was 48 years (16-80). Male represented 58%. Median MELD score was 16 (6-39), SOFA score was 8 (6-11). HM was higher in patients who had severe liver disease or critical illness measured by MELD, SOFA, APACHE II scores and number of failed organs (NFO), P < 0.05. Patients with day-1 lactate ≥ 2 mmol/L had increased HM (P < 0.001). MELD score performed as well as APACHE II, SOFA and NFO (P < 0.001) in predicting HM (AUROC = 0.84, 0.81, 0.79 and 0.82, respectively P > 0.05 for pair wise comparisons). Re-bleeding was associated with increased HM (56.9% vs. 31.6%, P = 0.002). The TG (n = 124) had less severe liver disease and critical illness and consequently had lower HM than local patients (32% vs. 57%, P = 0.002). TG patients with ≥2 endoscopies prior to transfer had increased 6-week mortality (P = 0.03). Time from bleeding to transfer ≥3 days was associated with re-bleeding (OR = 2.290, P = 0.043).

CONCLUSIONS

MELD score was comparable to ICU prognostic models in predicting mortality. Blood lactate was also predictive of hospital mortality. Delays in referrals and repeated endoscopy were associated with increased re-bleeding and mortality in this group.