A Phase 3 Trial of Seladelpar in Primary Biliary Cholangitis.

BACKGROUND: Effective treatments for patients with primary biliary cholangitis are limited. Seladelpar, a peroxisome proliferator-activated receptor delta agonist, has potential benefits. METHODS: In this phase 3, 12-month, double-blind, placebo-controlled trial, we randomly assigned (in a 2:1 ratio) patients who had had an inadequate response to or who had a history of unacceptable side effects with ursodeoxycholic acid to receive oral seladelpar at a dose of 10 mg daily or placebo. The primary end point was a biochemical response, which was defined as an alkaline phosphatase level less than 1.67 times the upper limit of the normal range, with a decrease of 15% or more from baseline, and a normal total bilirubin level at month 12. Key secondary end points were normalization of the alkaline phosphatase level at month 12 and a change in the score on the pruritus numerical rating scale (range, 0 [no itch] to 10 [worst itch imaginable]) from baseline to month 6 among patients with a baseline score of at least 4 (indicating moderate-to-severe pruritus). RESULTS: Of the 193 patients who underwent randomization and treatment, 93.8% received ursodeoxycholic acid as standard-of-care background therapy. A greater percentage of the patients in the seladelpar group than in the placebo group had a biochemical response (61.7% vs. 20.0%; difference, 41.7 percentage points; 95% confidence interval [CI], 27.7 to 53.4, P<0.001). Normalization of the alkaline phosphatase level also occurred in a greater percentage of patients who received seladelpar than of those who received placebo (25.0% vs. 0%; difference, 25.0 percentage points; 95% CI, 18.3 to 33.2, P<0.001). Seladelpar resulted in a greater reduction in the score on the pruritus numerical rating scale than placebo (least-squares mean change from baseline, -3.2 vs. -1.7; least-squares mean difference, -1.5; 95% CI, -2.5 to -0.5, P = 0.005). Adverse events were reported in 86.7% of the patients in the seladelpar group and in 84.6% in the placebo group, and serious adverse events in 7.0% and 6.2%, respectively. CONCLUSIONS: In this trial involving patients with primary biliary cholangitis, the percentage of patients who had a biochemical response and alkaline phosphatase normalization was significantly greater with seladelpar than with placebo. Seladelpar also significantly reduced pruritus among patients who had moderate-to-severe pruritus at baseline. The incidence and severity of adverse events were similar in the two groups. (Funded by CymaBay Therapeutics; RESPONSE ClinicalTrials.gov number, NCT04620733; EudraCT number, 2020-004348-27.).

A Randomized Trial of Albumin Infusions in Hospitalized Patients with Cirrhosis.

BACKGROUND: Infection and increased systemic inflammation cause organ dysfunction and death in patients with decompensated cirrhosis. Preclinical studies provide support for an antiinflammatory role of albumin, but confirmatory large-scale clinical trials are lacking. Whether targeting a serum albumin level of 30 g per liter or greater in these patients with repeated daily infusions of 20% human albumin solution, as compared with standard care, would reduce the incidences of infection, kidney dysfunction, and death is unknown. METHODS: We conducted a randomized, multicenter, open-label, parallel-group trial involving hospitalized patients with decompensated cirrhosis who had a serum albumin level of less than 30 g per liter at enrollment. Patients were randomly assigned to receive either targeted 20% human albumin solution for up to 14 days or until discharge, whichever came first, or standard care. Treatment commenced within 3 days after admission. The composite primary end point was new infection, kidney dysfunction, or death between days 3 and 15 after the initiation of treatment. RESULTS: A total of 777 patients underwent randomization, and alcohol was reported to be a cause of cirrhosis in most of these patients. A median total infusion of albumin of 200 g (interquartile range, 140 to 280) per patient was administered to the targeted albumin group (increasing the albumin level to ≥30 g per liter), as compared with a median of 20 g (interquartile range, 0 to 120) per patient administered to the standard-care group (adjusted mean difference, 143 g; 95% confidence interval [CI], 127 to 158.2). The percentage of patients with a primary end-point event did not differ significantly between the targeted albumin group (113 of 380 patients [29.7%]) and the standard-care group (120 of 397 patients [30.2%]) (adjusted odds ratio, 0.98; 95% CI, 0.71 to 1.33; P = 0.87). A time-to-event analysis in which data were censored at the time of discharge or at day 15 also showed no significant between-group difference (hazard ratio, 1.04; 95% CI, 0.81 to 1.35). More severe or life-threatening serious adverse events occurred in the albumin group than in the standard-care group. CONCLUSIONS: In patients hospitalized with decompensated cirrhosis, albumin infusions to increase the albumin level to a target of 30 g per liter or more was not more beneficial than the current standard care in the United Kingdom. (Funded by the Health Innovation Challenge Fund; ATTIRE EudraCT number, 2014-002300-24; ISRCT number, N14174793.).

UK-Wide Multicenter Evaluation of Second-line Therapies in Primary Biliary Cholangitis.

BACKGROUND & AIMS: Thirty-to-forty percent of patients with primary biliary cholangitis inadequately respond to ursodeoxycholic acid. Our aim was to assemble national, real-world data on the effectiveness of obeticholic acid (OCA) as a second-line treatment, alongside non-licensed therapy with fibric acid derivatives (bezafibrate or fenofibrate). METHODS: This was a nationwide observational cohort study conducted from August 2017 until June 2021. RESULTS: We accrued data from 457 patients; 349 treated with OCA and 108 with fibric acid derivatives. At baseline/pre-treatment, individuals in the OCA group manifest higher risk features compared with those taking fibric acid derivatives, evidenced by more elevated alkaline phosphatase values, and a larger proportion of individuals with cirrhosis, abnormal bilirubin, prior non-response to ursodeoxycholic acid, and elastography readings >9.6kPa (P < .05 for all). Overall, 259 patients (OCA) and 80 patients (fibric acid derivatives) completed 12 months of second-line therapy, yielding a dropout rate of 25.7% and 25.9%, respectively. At 12 months, the magnitude of alkaline phosphatase reduction was 29.5% and 56.7% in OCA and fibric acid groups (P < .001). Conversely, 55.9% and 36.4% of patients normalized serum alanine transaminase and bilirubin in the OCA group (P < .001). The proportion with normal alanine transaminase or bilirubin values in the fibric acid group was no different at 12 months compared with baseline. Twelve-month biochemical response rates were 70.6% with OCA and 80% under fibric acid treatment (P = .121). Response rates between treatment groups were no different on propensity-score matching or on sub-analysis of high-risk groups defined at baseline. CONCLUSION: Across the population of patients with primary biliary cholangitis in the United Kingdom, rates of biochemical response and drug discontinuation appear similar under fibric acid and OCA treatment.

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.

Targeted Albumin Therapy Does Not Improve Short-Term Outcome in Hyponatremic Patients Hospitalized With Complications of Cirrhosis: Data From the ATTIRE Trial.

INTRODUCTION: Patients with decompensated cirrhosis and hyponatremia have a poor prognosis. We investigated Albumin to Prevent Infection in Chronic Liver Failure trial data to determine whether targeted albumin infusions improved outcome in patients with hyponatremia at baseline. METHODS: We examined the interaction between targeted albumin and standard care for the composite primary end point, stratifying by baseline sodium ≥ and <130 mmol/L. RESULTS: Randomization to albumin was associated with a significant increase in sodium; however, there was no interaction between sodium category and treatment for the trial primary end point. DISCUSSION: Targeted intravenous albumin infusions increased serum sodium level in hospitalized hyponatremic patients with cirrhosis, but this did not improve outcome.

Clinical Ontologies Improve Case Finding of Primary Biliary Cholangitis in UK Primary and Secondary Care.

INTRODUCTION: PBC registries in the UK focus on data from secondary care without clear coordinated contribution from primary care. The Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) receives data from > 500 primary care practices (PCPs). Notably, the Lancet commissioning group is extracting data from the RCGP RSC database to shape UK policy on liver disease. AIMS: To create a novel ontology to facilitate PBC case finding from primary care provider (PCP) records. METHODS: RCGP RSC data were collected from participating PCPs in the county of Surrey, UK. PBC diagnostic criteria of the AASLD and EASL guidelines were used to develop 725 data codes to facilitate patient record searches. A scoring system built into the ontology allowed categorization of cases as PBC definite, PBC probable, and PBC unlikely. RESULTS: A total of 218,099 records were searched from participating PCPs. Of these, there were 58 PBC definite, 2317 PBC probable, and 215,724 PBC unlikely patients. There were 32 PBC definite patients who did not match to our regional PBC database and were henceforth included as new-found cases. Two of these cases were not labeled as PBC by the PCP. From the PBC unlikely group, 7/215,724 (0.003%) patients were labeled as PBC in secondary care records; however, none of them were coded as having PBC by their PCPs. CONCLUSIONS: Utilization of the UK National RCGP RSC database supported by novel ontology score has successfully helped us identify (i) new cases of PBC not known to local/regional secondary care providers and (ii) de novo PBC cases. There are many PBC probable cases whose data merit further careful evaluation.

Assessment of bone mineral density in tenofovir-treated patients with chronic hepatitis B: can the fracture risk assessment tool identify those at greatest risk?

BACKGROUND: Tenofovir disoproxil fumarate (TDF) is an established nucleotide analogue in the treatment of chronic hepatitis B. Bone mineral density loss has been described in TDF-treated patients with human immunodeficiency virus infection, but limited data exist for patients with chronic hepatitis B. Dual X-ray absorptiometry (DEXA) was used to determine bone mineral density changes in TDF-exposed patients. We evaluated the accuracy of the Fracture Risk Assessment Tool (FRAX) as an alternative to DEXA in clinical practice. METHODS: A total of 170 patients were studied: 122 were exposed to TDF, and 48 were controls. All patients underwent DEXA, and demographic details were recorded. FRAX scores (before and after DEXA) were calculated. RESULTS: TDF was associated with a lower hip T score (P = .02). On univariate and multivariate analysis, advancing age, smoking, lower body mass index, and TDF exposure were independent predictors of low bone mineral density. In addition, the pre-DEXA FRAX score was an accurate predictor of the post-DEXA FRAX treatment recommendation (100% sensitivity and 83% specificity), area under the curve 0.93 (95% CI, .87-.97, P < .001). CONCLUSIONS: TDF-treated patients with chronic hepatitis B have reduced bone mineral density, but the reduction is limited to 1 anatomical site. Age and advanced liver disease are additional contributing factors, underlining the importance of multifactorial fracture risk assessment. FRAX can accurately identify those at greatest risk of osteoporotic fracture.

Analysis of Endoscopic Radiofrequency Ablation of Biliary Malignant Strictures in Pancreatic Cancer Suggests Potential Survival Benefit.

BACKGROUND: Pancreatic carcinoma is often inoperable, carries a poor prognosis, and is commonly complicated by malignant biliary obstruction. Phase I/II studies have demonstrated good safety and early stent patency using endoscopic biliary radiofrequency ablation (RFA) as an adjunct to self-expanding metal stent (SEMS) insertion for biliary decompression. AIM: To analyze the clinical efficacy of endobiliary RFA. METHODS: Retrospective case-control analysis was carried out for 23 patients with surgically unresectable pancreatic carcinoma and malignant biliary obstruction undergoing endoscopic RFA and SEMS insertion and 46 controls (SEMS insertion alone) in a single tertiary care center. Controls were stringently matched for age, sex, metastases, ASA/comorbidities. Survival, morbidity, and stent patency rates were assessed. RESULTS: RFA and control groups were closely matched-ASA 2.35 ± 0.65 versus 2.54 ± 0.50, p = 0.086; metastases 9/23 (39.1%) versus 18/46 (39.1%), p = 0.800; chemotherapy 16/23 (69.6%) versus 24/46 (52.2%), p = 0.203. Median survival in RFA group was 226 days (IQR 140-526 days) versus 123.5 days (IQR 44-328 days) in controls (p = 0.010). RFA was independently predictive of survival at 90 days (OR 21.07, 95% CI 1.45-306.64, p = 0.026) and 180 days (OR 4.48, 95% CI 1.04-19.30, p = 0.044) in multivariate analysis. SEMS patency rates were equivalent in both groups. RFA was well tolerated with minimal side effects. CONCLUSIONS: Endoscopic RFA is a safe and efficacious adjunctive treatment in patients with advanced pancreatic malignancy and biliary obstruction and may confer early survival benefit. Randomized prospective clinical trials of this new modality are mandated.

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.

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.

Bone marrow-derived cells contribute to cerulein-induced pancreatic fibrosis in the mouse.

Bone marrow (BM) cells may transdifferentiate into circulating fibrocytes and myofibroblasts in organ fibrosis. In this study, we investigated the contribution and functional roles of BM-derived cells in murine cerulein-induced pancreatic fibrosis. C57/BL6 female mice wild-type (WT) or Col 1α1(r/r) male BM transplant, received supraphysiological doses of cerulein to induce pancreatic fibrosis. The CD45(+)Col 1(+) fibrocytes isolated from peripheral blood (PB) and pancreatic tissue were examined by in situ hybridization for Y chromosome detection. The number of BM-derived myofibroblasts, the degree of Sirius red staining and the levels of Col 1α1 mRNA were quantified. The Y chromosome was detected in the nuclei of PB CD45(+)Col 1(+) fibrocytes, confirming that circulating fibrocytes can be derived from BM. Co-expression of α-smooth muscle actin illustrated that fibrocytes can differentiate into myofibroblasts. The number of BM-derived myofibroblasts, degree of collagen deposition and pro-collagen I mRNA expression were higher in the mice that received Col 1α1(r/r) BM, (cells that produce mutated, collagenase-resistant collagen) compared to WT BM, indicating that the genotype of BM cells can alter the degree of pancreatic fibrosis. Our data indicate that CD45(+)Col 1(+) fibrocytes in the PB can be BM-derived, functionally contributing to cerulein-induced pancreatic fibrosis in mice by differentiating into myofibroblasts.

Remodelling of extracellular matrix is a requirement for the hepatic progenitor cell response.

BACKGROUND AND METHODS: In advanced liver damage, hepatic regeneration can occur through proliferation of a resident hepatic progenitor cell (HPC) population. HPCs are located within a designated niche in close association with myofibroblasts and bone marrow (BM) derived macrophages. Extra-cellular matrix (ECM) laminin invariably surrounds HPCs, but the functional requirement of this matrix-cell association is untested in vivo. Using the collagen Iα1((r/r)) mouse (r/r), which produces mutated collagen I resistant to matrix metalloproteinase degradation and has an exaggerated fibrotic response to liver injury, we test the relationship between collagen degradation, laminin deposition, and the HPC response. RESULTS: Chronic fibrotic carbon tetrachloride (CCl4) injury can induce a florid HPC response associated with dense laminin deposition. In the recovery phase after chronic CCl4 injury, r/r mice have a markedly attenuated HPC response compared to wild-types, together with persistence of collagen I and failure to deposit ECM laminin. Similar results were found in r/r mice given the choline-deficient ethionine supplemented diet, another model of the HPC response. In cross-over sex-mismatched BM transplantation (BMT) experiments between r/r mice and wild-types, the blunted HPC response of r/r mice was not rescued by wild-type BMT and likewise not conferred on to wild-type recipients by r/r BMT, demonstrating that the attenuated HPC response in r/r mice is a property intrinsic to the liver. CONCLUSION: Failure of ECM remodelling after chronic fibrotic liver injury hinders the ability of the liver to activate HPCs. Laminin-progenitor cell interactions within the HPC niche are a critical for HPC mediated regeneration.

ASEPTIC: primary antibiotic prophylaxis using co-trimoxazole to prevent SpontanEous bacterial PeritoniTIs in Cirrhosis-study protocol for an interventional randomised controlled trial.

BACKGROUND: Bacterial infection is a major cause of mortality in patients with cirrhosis. Spontaneous bacterial peritonitis (SBP) is a serious and common infection in patients with cirrhosis and ascites. Secondary prophylactic antibiotic therapy has been shown to improve outcomes after an episode of SBP but primary prophylaxis to prevent the first episode of SBP remains contentious. The aim of this trial is to assess whether primary antibiotic prophylaxis with co-trimoxazole improves overall survival compared to placebo in adults with cirrhosis and ascites. METHODS: The ASEPTIC trial is a multicentre, placebo-controlled, double-blinded, randomised controlled trial (RCT) in England, Scotland, and Wales. Patients aged 18 years and older with cirrhosis and ascites requiring diuretic treatment or paracentesis, and no current or previous episodes of SBP, are eligible, subject to exclusion criteria. The trial aims to recruit 432 patients from at least 30 sites. Patients will be randomised in a 1:1 ratio to receive either oral co-trimoxazole 960 mg or an identical placebo once daily for 18 months, with 6 monthly follow-up visits thereafter (with a maximum possible follow-up period of 48 months, and a minimum of 18 months). The primary outcome is overall survival. Secondary outcomes include the time to the first incidence of SBP, hospital admission rates, incidence of other infections (including Clostridium difficile) and antimicrobial resistance, patients' health-related quality of life, health and social care resource use, incidence of cirrhosis-related decompensation events, liver transplantation, and treatment-related serious adverse events. DISCUSSION: This trial will investigate the efficacy, safety, and cost-effectiveness of co-trimoxazole for patients with liver cirrhosis and ascites to determine whether this strategy improves clinical outcomes. Given there are no treatments that improve survival in decompensated cirrhosis outside of liver transplant, if the trial has a positive outcome, we anticipate widespread adoption of primary antibiotic prophylaxis. TRIAL REGISTRATION: ClinicalTrials.gov NCT043955365 . Registered on 18 April 2020. Research ethical approval was granted by the Research Ethics Committee (South Central - Oxford B; REC 19/SC/0311) and the Medicines and Healthcare products Regulatory Agency (MHRA).

An update on the management of cholestatic liver diseases.

Cholestatic liver diseases are a challenging spectrum of conditions arising from damage to bile ducts, leading to build-up of bile acids and inflammatory processes that cause injury to cholangiocytes and hepatocytes. Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are the two most common cholestatic disorders. In this review we detail the latest guidelines for the diagnosis and management of patients with these two conditions.

Proteinase activated receptor 1 mediated fibrosis in a mouse model of liver injury: a role for bone marrow derived macrophages.

Liver fibrosis results from the co-ordinated actions of myofibroblasts and macrophages, a proportion of which are of bone marrow origin. The functional effect of such bone marrow-derived cells on liver fibrosis is unclear. We examine whether changing bone marrow genotype can down-regulate the liver's fibrotic response to injury and investigate mechanisms involved. Proteinase activated receptor 1 (PAR1) is up-regulated in fibrotic liver disease in humans, and deficiency of PAR1 is associated with reduced liver fibrosis in rodent models. In this study, recipient mice received bone marrow transplantation from PAR1-deficient or wild-type donors prior to carbon tetrachloride-induced liver fibrosis. Bone marrow transplantation alone from PAR1-deficient mice was able to confer significant reductions in hepatic collagen content and activated myofibroblast expansion on wild-type recipients. This effect was associated with a decrease in hepatic scar-associated macrophages and a reduction in macrophage recruitment from the bone marrow. In vitro, PAR1 signalling on bone marrow-derived macrophages directly induced their chemotaxis but did not stimulate proliferation. These data suggest that the bone marrow can modulate the fibrotic response of the liver to recurrent injury. PAR1 signalling can contribute to this response by mechanisms that include the regulation of macrophage recruitment.