Investigating potential confounding by indication when considering the association between proton pump inhibitor use, infection, hepatic encephalopathy and mortality in hospitalised decompensated cirrhosis: a post-hoc analysis of the ATTIRE trial.

Background: Proton pump inhibitors (PPIs) are commonly prescribed to prevent and treat upper gastrointestinal ulceration and bleeding. Studies have identified increased incidence of spontaneous bacterial peritonitis and hepatic encephalopathy (HE) in cirrhosis patients taking PPIs. However, results are conflicting, and as PPIs are prescribed for variceal bleeding, a major risk factor for infection and HE, it is challenging to discern whether these associations are causal. Methods: In this post-hoc analysis of the ATTIRE trial, we pooled all patient data to investigate the effects of PPI use on clinical outcomes. ATTIRE was a multicentre, open-label, randomised trial of targeted 20% human albumin solution (HAS) daily infusions versus standard care involving 777 adults with decompensated cirrhosis hospitalised with acute complications and albumin <30 g/L. Study recruitment was between Jan 25, 2016, and June 28, 2019, at 35 hospitals across England, Scotland, and Wales. Key exclusion criteria were advanced hepatocellular carcinoma with life expectancy <8 weeks and patients receiving palliative care. In ATTIRE, patients were grouped by PPI use at trial entry. We studied infection and HE at baseline and incidence of hospital acquired infection, new onset HE, renal dysfunction and mortality. We attempted with propensity score matching to account for differences in disease severity. Findings: Overall PPI use at baseline was not associated with increased incidence of infection, renal dysfunction or mortality, but was associated with significantly increased incidence of grade III/IV HE during hospital stay (P = 0.011). This was only significant for those taking intravenous PPIs and these patients had >10 times the incidence of variceal bleeding and near double the 28-day mortality compared to non-PPI patients. However, propensity score matching was not possible as there was such a strong selection of patients for PPI use, that we could not find sufficient non-PPI patients to match to. We found no impact of PPI use on plasma markers of bacterial translocation, infection or systemic inflammation. Interpretations: Our real-world data from a completed randomised trial show that PPIs are widely prescribed in the UK and judicious use appears safe in patients hospitalised with decompensated cirrhosis. However, patients prescribed PPIs had fundamentally different phenotypes to those not prescribed PPIs, a form of confounding by indication, which should be strongly considered when interpreting studies and making recommendations about their use. Funding: Wellcome Trust and Department of Health and Social Care.

Evaluating the Role of Antibiotics in Patients Admitted to Hospital With Decompensated Cirrhosis: Lessons From the ATTIRE Trial.

INTRODUCTION: Hospital-acquired infections (HAI) are common in cirrhosis with antibiotics frequently used to prevent infections, but their efficacy for this role is unknown. To investigate this, we used Albumin to Prevent Infection in Chronic Liver Failure (ATTIRE) data to evaluate whether antibiotic use in patients without infection prevented HAI. METHODS: In ATTIRE patients without infection at baseline grouped by antibiotic prescription or not, we studied HAI during trial treatment period and mortality, with propensity score matching to account for differences in disease severity. RESULTS: Two hundred three of 408 patients prescribed antibiotics at enrollment did not have infection and they were more unwell than noninfected patients not given antibiotics. There were no differences in subsequent HAI comparing antibiotic treated (39/203, 19.2%) to nonantibiotic treated (73/360, 20.3%; P = 0.83). Twenty-eight-day mortality was higher in antibiotic-treated patients ( P = 0.004) likely reflecting increased disease severity. Matching groups using propensity scoring revealed no differences in HAI or mortality. In noninfected patients at enrollment treated with/without rifaximin, there were no differences in HAI ( P = 0.16) or mortality, confirmed with propensity matching. Patients given long-term antibiotic prophylaxis at discharge had no differences in 6-month mortality compared with nonantibiotic patients, although antibiotic-treated patients had more infections at trial entry, with numbers too small for matching. DISCUSSION: Half of antibiotics at study entry were given to patients without an infection diagnosis which did not reduce the overall risk of HAI or improve mortality. This supports prompt de-escalation or discontinuation of antibiotics guided by culture sensitivities at 24-48 hours after commencement if no infection and the patient is improving.

Use of non-selective B-blockers is safe in hospitalised decompensated cirrhosis patients and exerts a potential anti-inflammatory effect: Data from the ATTIRE trial.

Background: Nonselective B-blockers (NSBBs) are believed to have pleiotropic effects beyond reducing portal pressure. However, studies also report potential harm in patients hospitalized with cirrhosis and ascites. We therefore investigated whether NSBB use at ATTIRE trial entry (Albumin to prevent infection in chronic liver failure, 2016-19) was associated with increased renal or cardiovascular dysfunction, compared the incidence of infection and plasma markers of systemic inflammation, and examined mortality at 28-days, 3 and 6-months. Methods: In ATTIRE patients grouped by NSBB use at trial entry, we studied infection at baseline, hospital acquired infection and organ dysfunction during trial treatment period and mortality, with propensity score matching to account for differences in disease severity. Findings: There were no differences in renal or cardiovascular dysfunction between patients treated with NSBBs or not, during days 3-15 of hospitalization, despite elevated serum creatinine in NSBB patients at hospitalisation. Use of NSBBs was associated with a significant reduction in infection at hospitalization (p = 0.006), lower white cell counts throughout hospital stay (p < 0.001) and reduced plasma procalcitonin (p = 0.009) and interlukin-8 levels (p = 0.04) at baseline, but markers of bacterial translocation and systemic inflammation were the same in treatment groups. There was no reduction in hospital acquired infections in patients taking NSBBs and no beneficial impact on mortality at 28-days, 3 and 6-months. Interpretations: Our real-world data from a completed randomised trial show that use of NSBBs in decompensated cirrhosis patients is safe during hospitalisation. We also show a potential anti-inflammatory role for NSBBs which may be mediated by a downregulation of IL-8 induced leucocytosis, that was associated with reduced infection at baseline but not a survival benefit. Funding: Wellcome Trust and Department of Health and Social Care.

Targeted Albumin Infusions Do Not Improve Systemic Inflammation or Cardiovascular Function in Decompensated Cirrhosis.

INTRODUCTION: Albumin is recommended in decompensated cirrhosis, and studies have shown potential immunomodulatory effects. However, 2 large trials of repeated albumin infusions demonstrated contrasting results between outpatients and hospitalized patients. We investigated markers of systemic inflammation, immune function, albumin binding, and cardiovascular function using samples from Albumin To prevenT Infection in chronic liveR failurE (ATTIRE) taken at baseline, day 5, and day 10 of the trial to identify why targeted albumin infusions had no effect in hospitalized patients. METHODS: Plasma samples were analyzed from 143 patients (n = 71 targeted albumin; n = 72 standard care at baseline) for cytokines, cardiovascular markers, prostaglandin E2, the effect of plasma on macrophage function, and albumin radioligand binding and oxidation status. The sample size was based on our feasibility study, and samples were selected by a trial statistician stratified by the serum albumin level and the presence of infection at randomization and analyses performed blinded to the study arm. Data were linked to 3-month mortality and treatment groups compared. RESULTS: Increased baseline model for end-stage liver disease score, white cell count, calprotectin, CD163, tumor necrosis factor, renin, atrial natriuretic peptide, and syndecan-1 were associated with 3-month mortality. Despite infusing substantially differing volumes of albumin, there were no significant differences in inflammatory markers, albumin-prostaglandin E2 binding, or cardiovascular markers between treatment arms. DISCUSSION: Contrary to many preclinical studies, targeted intravenous albumin therapy in hospitalized decompensated cirrhosis had no effect across a broad range of systemic inflammation, albumin function, and cardiovascular mediators and biomarkers compared with standard care, consistent with the null clinical findings.

Monocyte dysfunction in decompensated cirrhosis is mediated by the prostaglandin E2-EP4 pathway.

BACKGROUND & AIMS: Infection is a major problem in advanced liver disease secondary to monocyte dysfunction. Elevated prostaglandin (PG)E2 is a mediator of monocyte dysfunction in cirrhosis; thus, we examined PGE2 signalling in outpatients with ascites and in patients hospitalised with acute decompensation to identify potential therapeutic targets aimed at improving monocyte dysfunction. METHODS: Using samples from 11 outpatients with ascites and 28 patients hospitalised with decompensated cirrhosis, we assayed plasma levels of PGE2 and lipopolysaccharide (LPS); performed quantitative real-time PCR on monocytes; and examined peripheral blood monocyte function. We performed western blotting and immunohistochemistry for PG biosynthetic machinery expression in liver tissue. Finally, we investigated the effect of PGE2 antagonists in whole blood using polychromatic flow cytometry and cytokine production. RESULTS: We show that hepatic production of PGE2 via the cyclo-oxygenase 1-microsomal PGE synthase 1 pathway, and circulating monocytes contributes to increased plasma PGE2 in decompensated cirrhosis. Transjugular intrahepatic sampling did not reveal whether hepatic or monocytic production was larger. Blood monocyte numbers increased, whereas individual monocyte function decreased as patients progressed from outpatients with ascites to patients hospitalised with acute decompensation, as assessed by Human Leukocyte Antigen (HLA)-DR isotype expression and tumour necrosis factor alpha and IL6 production. PGE2 mediated this dysfunction via its EP4 receptor. CONCLUSIONS: PGE2 mediates monocyte dysfunction in decompensated cirrhosis via its EP4 receptor and dysfunction was worse in hospitalised patients compared with outpatients with ascites. Our study identifies a potential drug target and therapeutic opportunity in these outpatients with ascites to reverse this process to prevent infection and hospital admission. LAY SUMMARY: Patients with decompensated cirrhosis (jaundice, fluid build-up, confusion, and vomiting blood) have high infection rates that lead to high mortality rates. A white blood cell subset, monocytes, function poorly in these patients, which is a key factor underlying their sensitivity to infection. We show that monocyte dysfunction in decompensated cirrhosis is mediated by a lipid hormone in the blood, prostaglandin E2, which is present at elevated levels, via its EP4 pathway. This dysfunction worsens when patients are hospitalised with complications of cirrhosis compared with those in the outpatients setting, which supports the EP4 pathway as a potential therapeutic target for patients to prevent infection and hospitalisation.

PPARγ S273 Phosphorylation Modifies the Dynamics of Coregulator Proteins Recruitment.

The nuclear receptor PPARγ is essential to maintain whole-body glucose homeostasis and insulin sensitivity, acting as a master regulator of adipogenesis, lipid, and glucose metabolism. Its activation through natural or synthetic ligands induces the recruitment of coactivators, leading to transcription of target genes such as cytokines and hormones. More recently, post translational modifications, such as PPARγ phosphorylation at Ser273 by CDK5 in adipose tissue, have been linked to insulin resistance trough the dysregulation of expression of a specific subset of genes. Here, we investigate how this phosphorylation may disturb the interaction between PPARγ and some coregulator proteins as a new mechanism that may leads to insulin resistance. Through cellular and in vitro assays, we show that PPARγ phosphorylation inhibition increased the activation of the receptor, therefore the increased recruitment of PGC1-α and TIF2 coactivators, whilst decreases the interaction with SMRT and NCoR corepressors. Moreover, our results show a shift in the coregulators interaction domains preferences, suggesting additional interaction interfaces formed between the phosphorylated PPARγ and some coregulator proteins. Also, we observed that the CDK5 presence disturb the PPARγ-coregulator's synergy, decreasing interaction with PGC1-α, TIF2, and NCoR, but increasing coupling of SMRT. Finally, we conclude that the insulin resistance provoked by PPARγ phosphorylation is linked to a differential coregulators recruitment, which may promote dysregulation in gene expression.

GQ-130, a novel analogue of thiazolidinedione, improves obesity-induced metabolic alterations in rats: Evidence for the involvement of PPARß/δ pathway.

The present investigation aimed to characterize the effect of a short-time treatment with a new thiazolidinedione (TZD) derivative, GQ-130, on metabolic alterations in rats fed a high-fat diet (HFD). We investigated whether metabolic alterations induced by GQ-130 were mediated though a mechanism that involves PPARß/δ transactivation. Potential binding and transactivation of PPARα, PPARß/δ or PPARγ by GQ-130 were examined through cell transactivation, 8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence quenching assays and thermal shift assay. For in vivo experiments, male 8-week-old Wistar rats were divided into three groups fed for 6 weeks with: (a) a standard rat chow (14% fat) (control group), (b) a HFD (57.8% fat) alone (HFD group), or (c) a HFD associated with an oral treatment with GQ-130 (10 mg/kg/d) during the last week (HFD-GQ group). In 293T cells, unlike rosiglitazone, GQ-130 did not cause significant transactivation of PPARγ but was able to activate PPARß/δ by 153.9 folds in comparison with control values (DMSO). Surprisingly, ANS fluorescence quenching assay reveals that GQ-130 does not bind directly to PPARß/δ binding site, a finding that was further corroborated by thermal shift assay which evaluates the thermal stability of PPARß/δ in the presence of GQ-130. Compared to the control group, rats of the HFD group showed obesity, increased systolic blood pressure (SBP), insulin resistance, impaired glucose intolerance, hyperglycaemia, and dyslipidaemia. GQ-130 treatment abolished the increased SBP and improved all metabolic dysfunctions observed in the HFD group. Oral treatment with GQ-130 was effective in improving HFD-induced metabolic alterations probably through a mechanism that involves PPARß/δ activation.

Screening for PPAR Non-Agonist Ligands Followed by Characterization of a Hit, AM-879, with Additional No-Adipogenic and cdk5-Mediated Phosphorylation Inhibition Properties.

Peroxisome proliferator-activated receptor gamma (PPARγ) is a member of a nuclear receptor superfamily and acts as a ligand-dependent transcription factor, playing key roles in maintenance of adipose tissue and in regulation of glucose and lipid homeostasis. This receptor is the target of thiazolidinediones, a class of antidiabetic drugs, which improve insulin sensitization and regulate glycemia in type 2 diabetes. Despite the beneficial effects of drugs, such as rosiglitazone and pioglitazone, their use is associated with several side effects, including weight gain, heart failure, and liver disease, since these drugs induce full activation of the receptor. By contrast, a promising activation-independent mechanism that involves the inhibition of cyclin-dependent kinase 5 (CDK5)-mediated PPARγ phosphorylation has been related to the insulin-sensitizing effects induced by these drugs. Thus, we aimed to identify novel PPARγ ligands that do not possess agonist properties by conducting a mini-trial with 80 compounds using the sequential steps of thermal shift assay, 8-anilino-1-naphthalenesulfonic acid fluorescence quenching, and a cell-based transactivation assay. We identified two non-agonist PPARγ ligands, AM-879 and P11, and one partial-agonist, R32. Using fluorescence anisotropy, we show that AM-879 does not dissociate the NCOR corepressor in vitro, and it has only a small effect on TRAP coactivator recruitment. In cells, AM-879 could not induce adipocyte differentiation or positively regulate the expression of genes associated with adipogenesis. In addition, AM-879 inhibited CDK5-mediated phosphorylation of PPARγ in vitro. Taken together, these findings supported an interaction between AM-879 and PPARγ; this interaction was identified by the analysis of the crystal structure of the PPARγ:AM-879 complex and evidenced by AM-879's mechanism of action as a putative PPARγ non-agonist with antidiabetic properties. Moreover, we present an optimized assay pipeline capable of detecting ligands that physically bind to PPARγ but do not cause its activation as a new strategy to identify ligands for this nuclear receptor.