The multifactorial mechanisms of bacterial infection in decompensated cirrhosis

Infections in cirrhosis

Cirrhosis is an immune dysfunction state, and as such, patients with cirrhosis are susceptible to bacterial, fungal, and viral infections. Because of infection, these patients have a propensity to develop multiorgan failure, which is associated with high mortality. Bacterial infections are the most prevalent type of infection in patients with cirrhosis, with the prevalence of bacterial infections in patients admitted for an acute decompensating event ranging from 24% to 29%. Together with invasive fungal infections, bacterial infections are the most severe. Multidrug-resistant organisms have been evolving at a rapid and alarming rate around the world, which presents enormous challenges. The development of effective measures for the prevention, early detection, and treatment of infections in patients with cirrhosis is challenging, given the rising incidence of infections in this patient population.

Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages

Colorectal cancer and Crohn's disease patients develop pyogenic liver abscesses due to failures of immune cells to fight off bacterial infections. Here, we show that mice lacking iron regulatory protein 2 (Irp2), globally (Irp2-/-) or myeloid cell lineage (Lysozyme 2 promoter-driven, LysM)-specifically (Irp2ΔLysM), are highly susceptible to liver abscesses when the intestinal tissue was injured with dextran sodium sulfate treatment. Further studies demonstrated that Irp2 is required for lysosomal acidification and biogenesis, both of which are crucial for bacterial clearance. In Irp2-deficient liver tissue or macrophages, the nuclear location of transcription factor EB (Tfeb) was remarkably reduced, leading to the downregulation of Tfeb target genes that encode critical components for lysosomal biogenesis. Tfeb mislocalization was reversed by hypoxia-inducible factor 2 inhibitor PT2385 and, independently, through inhibition of lactic acid production. These experimental findings were confirmed clinically in patients with Crohn's disease and through bioinformatic searches in databases from Crohn's disease or ulcerative colitis biopsies showing loss of IRP2 and transcription factor EB (TFEB)-dependent lysosomal gene expression. Overall, our study highlights a mechanism whereby Irp2 supports nuclear translocation of Tfeb and lysosomal function, preserving macrophage antimicrobial activity and protecting the liver against invading bacteria during intestinal inflammation.

Type-I interferon shapes peritoneal immunity in cirrhosis and drives caspase-5-mediated progranulin release upon infection

BACKGROUND & AIMS

Gut bacterial translocation contributes to immune dysfunction and spontaneous bacterial peritonitis (SBP) in cirrhosis. We hypothesized that exposure of peritoneal macrophages (PMs) to bacterial DNA results in type-I interferon (IFN) production, shaping subsequent immune responses, inflammasome activation, and the release of damage-associated molecular patterns (DAMPs).

METHODS

PMs from patients with cirrhosis were stimulated with E. coli single-stranded DNA (ssDNA), lipopolysaccharide and IFN, or infected with E. coli, S. aureus, and Group B streptococcus in vitro. Cytokine release, inflammasome activation, and DAMP release were quantified by quantitative-PCR, ELISA, western blots, and reporter cells employing primary PMs, monocytes, and caspase-deficient THP-1 macrophages. Serum progranulin concentration was correlated with transplant-free survival in 77 patients with SBP.

RESULTS

E. coli ssDNA induced strong type-I IFN activity in PMs and monocytes, priming them for enhanced lipopolysaccharide-mediated tumor necrosis factor production without inducing toll-like receptor 4 tolerance. During in vitro macrophage bacterial infection, type-I IFN release aligned with upregulated expression of IFN-regulatory factors (IRF)1/2 and guanylate binding proteins (GBP)2/5. PMs upregulated inflammasome-associated proteins and type-I IFN upon E. coli ssDNA exposure and released interleukin-1β upon bacterial infection. Proteomic screening in mouse macrophages revealed progranulin release as being caspase-11-dependent during E. coli infection. PMs and THP-1 macrophages released significant amounts of progranulin when infected with S. aureus or E. coli via gasdermin D in a type-I IFN- and caspase-5-dependent manner. During SBP, PMs upregulated IRF1, GBP2/5 and caspase-5 and higher serum progranulin concentrations were indicative of lower 90-day transplant-free survival after SBP.

CONCLUSIONS

Type-I IFN shapes peritoneal immune responses and regulates caspase-5-mediated progranulin release during SBP.

IMPACT AND IMPLICATIONS

Patients with cirrhosis exhibit impaired immune responses and increased susceptibility to bacterial infections. This study reveals that type-I interferon responses, triggered by pathogen-associated molecular patterns, are crucial in regulating macrophage activation and priming them for inflammatory responses. Additionally, we elucidate the mechanisms by which type-I interferons promote the release of progranulin from macrophages during spontaneous bacterial peritonitis. Our findings enhance understanding of how bacterial translocation affects immune responses, identify novel biomarkers for inflammasome activation during infections, and point to potential therapeutic targets.

Liver transplantation for acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) occurs in the context of advanced liver disease and is associated with hepatic and extrahepatic organ failure, eventually leading to a major risk of short-term mortality. To date, there are very few effective therapeutic options for ACLF. In many cases, liver transplantation is the only life-saving treatment that has acceptable outcomes in carefully selected recipients. This Review addresses key aspects of the use of liver transplantation for patients with ACLF, providing an in-depth discussion of existing evidence regarding candidate selection, the optimal window for transplantation, potential prioritisation of liver grafts for this indication, and the global management of ACLF to bridge patients to liver transplantation.

Distinct immunometabolic signatures in circulating immune cells define disease outcome in acute-on-chronic liver failure

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is a complication of cirrhosis characterized by multiple organ failure and high short-term mortality. The pathophysiology of ACLF involves elevated systemic inflammation leading to organ failure, along with immune dysfunction that heightens susceptibility to bacterial infections. However, it is unclear how these aspects are associated with recovery and nonrecovery in ACLF.

APPROACH AND RESULTS

Here, we mapped the single-cell transcriptome of circulating immune cells from patients with ACLF and acute decompensated (AD) cirrhosis and healthy individuals. We further interrogate how these findings, as well as immunometabolic and functional profiles, associate with ACLF-recovery (ACLF-R) or nonrecovery (ACLF-NR). Our analysis unveiled 2 distinct states of classical monocytes (cMons). Hereto, ACLF-R cMons were characterized by transcripts associated with immune and stress tolerance, including anti-inflammatory genes such as RETN and LGALS1 . Additional metabolomic and functional validation experiments implicated an elevated oxidative phosphorylation metabolic program as well as an impaired ACLF-R cMon functionality. Interestingly, we observed a common stress-induced tolerant state, oxidative phosphorylation program, and blunted activation among lymphoid populations in patients with ACLF-R. Conversely, ACLF-NR cMon featured elevated expression of inflammatory and stress response genes such as VIM , LGALS2 , and TREM1 , along with blunted metabolic activity and increased functionality.

CONCLUSIONS

This study identifies distinct immunometabolic cellular states that contribute to disease outcomes in patients with ACLF. Our findings provide valuable insights into the pathogenesis of ACLF, shedding light on factors driving either recovery or nonrecovery phenotypes, which may be harnessed as potential therapeutic targets in the future.

Clinical impact of multidrug-resistant bacterial infections in patients with cirrhosis

Aim: Recently, the emergency of multidrug-resistant organisms (MDRO) has complicated the management of bacterial infections (BI) in cirrhosis. We aimed to assess their clinical impact on patients with decompensated cirrhosis. Methods: A retrospective study included consecutive cirrhotic patients hospitalized for acute decompensation (AD) between January 2010 and December 2019. Results: A total of 518 AD admissions in 219 patients were included, with 260 BI episodes (50.2%). MDRO prevalence was 38.2% of the total isolates. Recent antibiotic use (OR = 4.91), nosocomial infection (OR = 2.95), and healthcare-associated infection (OR = 3.45) were their main risk factors. MDROs were associated with empiric treatment failure (OR = 23.42), a higher prevalence of sepsis (OR = 4.93), ACLF (OR = 3.42) and mortality. Conclusion: The clinical impact of MDROs was pejorative, with an increased risk of empiric treatment failure, organ failure and death.

Histological characteristics in patients admitted to the hospital with alcoholic hepatitis complicated by acute-on-chronic liver failure

OBJECTIVES

Alcoholic hepatitis (AH) is a frequent precipitating event for the development of acute-on-chronic liver failure (ACLF), a syndrome characterised by organ failures due to immune dysfunction. The histological features of this complication are not well characterized. We investigated whether ACLF has specific histological characteristics.

METHODS

Prospective cohort study in consecutive adult patients admitted between 03-2008 and 04-2021 to a tertiary referral centre with suspected AH. Diagnosis of AH was based on clinical presentation and confirmed by transjugular liver biopsy. All biopsies were assessed by a dedicated liver pathologist, blinded for clinical data and outcome. Diagnosis of ACLF was based on EASL-CLIF criteria. Histological and clinical characteristics of patients with and without ACLF at baseline were compared.

RESULTS

184 patients with biopsy-proven AH were enrolled. Median time from hospital admission to transjugular biopsy was 4.5 days (IQR 2-8). At baseline, ACLF was present in 73 patients (39.7%). Out of the 110 patients without ACLF at baseline, 30 (27.3%) developed ACLF within 28 days (median 7.5 days (IQR 2-20)). At baseline, ductular bilirubinostasis (DB) was the only histological feature significantly more frequently present in patients with ACLF compared to patients without ACLF (50.7% vs. 30.6%, p = 0.003). No clear association between histological features and the development of ACLF later on could be demonstrated.

CONCLUSIONS

In this well-defined cohort of patients with biopsy-proven AH, DB was associated with the presence of ACLF. This finding fits with the pathophysiology of this syndrome, which is characterized by systemic inflammation and an increased risk of infections.

Retrospective study of the incidence, risk factors, treatment outcomes of bacterial infections at uncommon sites in cirrhotic patients

BACKGROUND

Bacterial infections (BI) negatively affect the natural course of cirrhosis. The most frequent BI are urinary tract infections (UTI), pneumonia, and spontaneous-bacterial peritonitis (SBP).

AIM

To assess the relevance of bacterial infections beyond the commonly recognized types in patients with cirrhosis and to investigate their relationship with other clinical variables.

METHODS

We retrospectively analyzed patients with cirrhosis and BI treated between 2015 and 2018 at our tertiary care center. BIs were classified as typical and atypical, and clinical as well as laboratory parameters were compared between the two groups.

RESULTS

In a cohort of 488 patients with cirrhosis, we identified 225 typical BI (95 UTI, 73 SBP, 72 pulmonary infections) and 74 atypical BIs, predominantly cholangitis and soft tissue infections (21 each), followed by intra-abdominal BIs (n = 9), cholecystitis (n = 6), head/throat BIs (n = 6), osteoarticular BIs (n = 5), and endocarditis (n = 3). We did not observe differences concerning age, sex, or etiology of cirrhosis in patients with typical vs atypical BI. Atypical BIs were more common in patients with more advanced cirrhosis, as evidenced by Model of End Stage Liver Disease (15.1 ± 7.4 vs 12.9 ± 5.1; P = 0.005) and Child-Pugh scores (8.6 ± 2.5 vs 8.0 ± 2; P = 0.05).

CONCLUSION

Atypical BIs in cirrhosis patients exhibit a distinct spectrum and are associated with more advanced stages of the disease. Hence, the work-up of cirrhosis patients with suspected BI requires detailed work-up to elucidate whether typical BI can be identified.

Liver cirrhosis and antibiotic therapy but not TIPS application leads to a shift of the intestinal bacterial communities: A controlled, prospective study

OBJECTIVES

The gut-liver axis is discussed to play an important role in hepatic cirrhosis. Decompensated liver cirrhosis is associated with portal hypertension, which can lead to a variety of complications. Transjugular intrahepatic portosystemic shunt (TIPS) is an established treatment option for the complications of portal hypertension. In this study we focused on the effect of TIPS on intestinal microbial composition in cirrhotic patients.

METHODS

Thirty patients with liver cirrhosis were compared to 18 healthy adults. Seventeen patients with cirrhosis and portal hypertension received a TIPS. Clinical characteristics, including age, sex, and liver function measured with a Child-Pugh score and model for end-stage liver disease score, were obtained. Intestinal microbial composition was assessed via 16S rRNA gene amplicon sequencing from stool probes before and after TIPS.

RESULTS

TIPS led to a reduction of hepatic venous pressure gradient. However, TIPS did not cause a shift in the intestinal bacterial communities. Independent from the application of TIPS, antibiotic therapy was associated with a significant difference in the intestinal bacterial microbiota and also a reduced α-diversity. In addition, a significant difference was observed in the intestinal bacterial composition between patients with liver cirrhosis and healthy controls.

CONCLUSION

The presence of liver cirrhosis and the use of antibiotic therapy, but not the application of TIPS, were associated with a significant shift of the intestinal bacterial communities, showing a high impact on the microbiota of patients with liver cirrhosis.

Human Amniotic MSC Response in LPS-Stimulated Ascites from Patients with Cirrhosis: FOXO1 Gene and Th17 Activation in Enhanced Antibacterial Activation

Spontaneous bacterial peritonitis (SBP) is a severe complication in patients with decompensated liver cirrhosis and is commonly treated with broad spectrum antibiotics. However, the rise of antibiotic resistance requires alternative therapeutic strategies. As recently shown, human amnion-derived mesenchymal stem cells (hA-MSCs) are able, in vitro, to promote bacterial clearance and modulate the immune and inflammatory response in SBP. Our results highlight the upregulation of FOXO1, CXCL5, CXCL6, CCL20, and MAPK13 in hA-MSCs as well as the promotion of bacterial clearance, prompting a shift in the immune response toward a Th17 lymphocyte phenotype after 72 h treatment. In this study, we used an in vitro SBP model and employed omics techniques (next-generation sequencing) to investigate the mechanisms by which hA-MSCs modify the crosstalk between immune cells in LPS-stimulated ascitic fluid. We also validated the data obtained via qRT-PCR, cytofluorimetric analysis, and Luminex assay. These findings provide further support to the hope of using hA-MSCs for the prevention and treatment of infective diseases, such as SBP, offering a viable alternative to antibiotic therapy.

Systematic review of the role of calprotectin in cirrhosis

BACKGROUND

Calprotectin is a calcium-binding-S100-protein synthetized mainly in neutrophils which has been demonstrated to be an accurate biomarker of the presence of these cells. Gut barrier dysfunction in patients with advanced chronic liver disease (ACLD), in addition to the lack of noninvasive tools for diagnosis and prognosis of cirrhosis decompensations, has raised interest in this biomarker.

AIMS

Our aim is to summarize the current evidence regarding the role of calprotectin in terms of its diagnostic and prognostic utility in ACLD.

METHODS

We performed a systematic search (PROSPERO registration no. CRD42023389069) of original articles published without any restrictions on the publication date until January 2023 providing information about calprotectin for the prognosis or diagnosis of ACLD and its decompensations in adult patients.

RESULTS

A total 227 articles were identified, and 26 observational studies finally met the inclusion criteria. In 14 studies, calprotectin was measured in ascitic fluid, all of which reported higher calprotectin values in spontaneous bacterial peritonitis, while cut-off points for its diagnosis were proposed in nine studies. Three studies reported higher faecal calprotectin levels in patients with hepatic encephalopathy and portal hypertension. Four studies evaluated faecal calprotectin and one plasma calprotectin as biomarkers for gut barrier integrity and bacterial translocation.

CONCLUSIONS

Calprotectin is emerging as a promising biomarker in ACLD, particularly for the management of bacterial infections and alcohol-related liver disease. Further research with better study designs should help to determine the feasibility of calprotectin measurement in routine clinical practice.

Risk factors for pre-transplantation bacteremia in adults with end-stage liver disease: Effects on outcomes of liver transplantation

BACKGROUND AND AIM

Limited data are available regarding pre-liver transplantation (LT) bacteremia in adults with end-stage liver disease. In this study, we investigated the risk factors independently associated with pre-LT bacteremia and their effects on clinical outcomes of LT.

METHODS

This retrospective study performed between 2010 and 2021 included 1287 LT recipients. The study population was categorized into patients with pre-LT bacteremia and those without pre-LT infection. Pre-LT bacteremia was defined as bacteremia detected within 90 days before LT.

RESULTS

Among 1287 LT recipients, 92 (7.1%) developed pre-LT bacteremia. The mean interval between bacteremia and LT was 28.3 ± 19.5 days. Of these 92 patients, seven (7.6%) patients died after LT. Of the 99 microorganisms isolated in this study, gram-negative bacteria were the most common microbes (72.7%). Bacteremia was mainly attributed to spontaneous bacterial peritonitis. The most common pathogen isolated was Escherichia coli (25.2%), followed by Klebsiella pneumoniae (18.2%), and Staphylococcus aureus (15.1%). Multivariate analysis showed that massive ascites (adjusted odds ratio [OR] 1.67, 95% confidence Interval [CI] 1.048-2.687) and a prolonged international normalized ratio for prothrombin time (adjusted OR 1.13, 95% CI 1.074-1.257) were independent risk factors for pre-LT bacteremia in patients with end-stage liver disease. Intensive care unit and in-hospital stay were significantly longer, and in-hospital mortality was significantly higher among LT recipients with pre-LT bacteremia than among those without pre-LT infection.

CONCLUSIONS

This study highlights predictors of pre-LT bacteremia in patients with end-stage liver disease. Pre-LT bacteremia increases the post-transplantation mortality risk.

Recompensation in cirrhosis: unravelling the evolving natural history of nonalcoholic fatty liver disease

Recompensation has gained increasing attention in the field of cirrhosis, particularly in chronic liver disease with a definite aetiology. The current global prevalence of obesity and nonalcoholic fatty liver disease (NAFLD) is increasing, but there is currently a lack of a clear definition for recompensation in NAFLD-related cirrhosis. Here, we provide an up-to-date perspective on the natural history of NAFLD, emphasizing the reversible nature of the disease, summarizing possible mechanisms underlying recompensation in NAFLD, discussing challenges that need to be addressed and outlining future research directions in the field. Recompensation is a promising goal in patients with NAFLD-related cirrhosis, and further studies are needed to explore its underlying mechanisms and uncover its clinical features.

Risk of Severe Infection in Patients With Biopsy-proven Nonalcoholic Fatty Liver Disease - A Population-based Cohort Study

BACKGROUND & AIMS

It has been suggested that patients with nonalcoholic fatty liver disease (NAFLD) might be at increased risk of severe infections, but large-scale data from cohorts with biopsy-proven NAFLD are lacking.

METHODS

Population-based cohort study including all Swedish adults with histologically confirmed NAFLD (n = 12,133) from 1969 to 2017. NAFLD was defined as simple steatosis (n = 8232), nonfibrotic steatohepatitis (n = 1378), noncirrhotic fibrosis (n = 1845), and cirrhosis (n = 678). Patients were matched to ≤5 population comparators (n = 57,516) by age, sex, calendar year, and county. Swedish national registers were used to ascertain incident severe infections requiring hospital admission. Multivariable adjusted Cox regression was used to estimate hazard ratios in NAFLD and histopathological subgroups.

RESULTS

Over a median of 14.1 years, 4517 (37.2%) patients with NAFLD vs 15,075 (26.2%) comparators were hospitalized for severe infections. Patients with NAFLD had higher incidence of severe infections than comparators (32.3 vs. 17.0/1000 person-years; adjusted hazard ratio [aHR], 1.71; 95% confidence interval, 1.63-1.79). The most frequent infections were respiratory (13.8/1000 person-years) and urinary tract infections (11.4/1000 person-years). The absolute risk difference at 20 years after NAFLD diagnosis was 17.3%, equal to one extra severe infection in every 6 patients with NAFLD. Risk of infection increased with worsening histological severity of NAFLD (simple steatosis [aHR, 1.64], nonfibrotic steatohepatitis [aHR, 1.84], noncirrhotic fibrosis [aHR, 1.77], and cirrhosis [aHR, 2.32]. Also compared with their full siblings, patients with NAFLD were at increased risk of severe infections (aHR, 1.54; 95% confidence interval, 1.40-1.70).

CONCLUSIONS

Patients with biopsy-proven NAFLD were at significantly higher risk of incident severe infection requiring hospitalization both compared with the general population and compared with siblings. Excess risk was evident across all stages of NAFLD and increased with worsening disease severity.

Antibiotic use and development of nonalcoholic fatty liver disease: A population-based case-control study

BACKGROUND AND AIMS

Antibiotics affect the gut microbiome. Preclinical studies suggest a role of gut dysbiosis in the development of nonalcoholic fatty liver disease (NAFLD), but data from large cohorts with liver histology are lacking.

METHODS

In this nationwide case-control study, Swedish adults with histologically confirmed early-stage NAFLD (total n = 2584; simple steatosis n = 1435; steatohepatitis (NASH) n = 383; non-cirrhotic fibrosis n = 766) diagnosed January 2007-April 2017 were included and matched to ≤5 population controls (n = 12 646) for age, sex, calendar year and county of residence. Data for cumulative antibiotic dispensations and defined daily doses were accrued until 1 year before the matching date. Using conditional logistic regression, multivariable-adjusted odds ratios (aORs) were calculated. In a secondary analysis, NAFLD patients were compared with their full siblings (n = 2837).

RESULTS

Previous antibiotic use was seen in 1748 (68%) NAFLD patients versus 7001 (55%) controls, corresponding to 1.35-fold increased odds of NAFLD (95% CI = 1.21-1.51) in a dose-dependent manner (pfor trend  < .001). Estimates were comparable for all histologic stages (p > .05). The highest risk of NAFLD was observed after treatment with fluoroquinolones (aOR 1.38; 95% CI = 1.17-1.59). Associations remained robust when patients were compared with their full siblings (aOR 1.29; 95% CI = 1.08-1.55). Antibiotic treatment was only linked to NAFLD in patients without metabolic syndrome (aOR 1.63; 95% CI = 1.35-1.91) but not in those with metabolic syndrome (aOR 1.09; 95% CI = 0.88-1.30).

CONCLUSIONS

Antibiotic use may be a risk factor for incident NAFLD, especially in individuals without the metabolic syndrome. The risk was highest for fluoroquinolones and remained robust in sibling comparisons with whom individuals share genetic and early environmental susceptibilities.

Clinical Data based XGBoost Algorithm for infection risk prediction of patients with decompensated cirrhosis: a 10-year (2012-2021) Multicenter Retrospective Case-control study

OBJECTIVES

To appraise effective predictors for infection in patients with decompensated cirrhosis (DC) by using XGBoost algorithm in a retrospective case-control study.

METHODS

Clinical data were retrospectively collected from 6,648 patients with DC admitted to five tertiary hospitals. Indicators with significant differences were determined by univariate analysis and least absolute contraction and selection operator (LASSO) regression. Further multi-tree extreme gradient boosting (XGBoost) machine learning-based model was used to rank importance of features selected from LASSO and subsequently constructed infection risk prediction model with simple-tree XGBoost model. Finally, the simple-tree XGBoost model is compared with the traditional logical regression (LR) model. Performances of models were evaluated by area under the receiver operating characteristic curve (AUROC), sensitivity, and specificity.

RESULTS

Six features, including total bilirubin, blood sodium, albumin, prothrombin activity, white blood cell count, and neutrophils to lymphocytes ratio were selected as predictors for infection in patients with DC. Simple-tree XGBoost model conducted by these features can predict infection risk accurately with an AUROC of 0.971, sensitivity of 0.915, and specificity of 0.900 in training set. The performance of simple-tree XGBoost model is better than that of traditional LR model in training set, internal verification set, and external feature set (P < 0.001).

CONCLUSIONS

The simple-tree XGBoost predictive model developed based on a minimal amount of clinical data available to DC patients with restricted medical resources could help primary healthcare practitioners promptly identify potential infection.

Roles of systemic inflammatory and metabolic responses in the pathophysiology of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is the most severe form of acutely decompensated cirrhosis and is characterised by the presence of one or more organ failures, intense systemic inflammation, peripheral blood lymphopenia, and a high risk of death without liver transplantation within 28 days. Herein, we propose the hypothesis that intense systemic inflammation may lead to organ failures through five different non-mutually exclusive mechanisms. First, pathogen-associated molecular patterns and inflammatory mediators (i.e. cytokines and lipid mediators) stimulate the production of the vasorelaxant nitric oxide in the walls of splanchnic arterioles, leading to enhanced splanchnic and systemic vasodilation which, in turn, induces enhanced activity of endogenous vasoconstrictor systems causing renal vasoconstriction and acute kidney injury. Second, neutrophils that reach the systemic circulation are prone to adhere to the vascular endothelium. Cytokines and lipid mediators act on the endothelium in microvessels of vital organs, an effect that favours the migration of neutrophils (and probably other leukocytes) to surrounding tissues where neutrophils can cause tissue damage and thereby contribute to organ failure. Third, cytokines and lipid mediators promote the formation of microthrombi that impair microcirculation and tissue oxygenation. Fourth, acute inflammation stimulates intense peripheral catabolism of amino acids whose products may be metabotoxins that contribute to hepatic encephalopathy. Fifth, acute inflammatory responses, which include the production of a broad variety of biomolecules (proteins and lipids), and an increase in biomass (i.e., granulopoiesis requiring de novo nucleotide synthesis), among others, are energetically expensive processes that require large amounts of nutrients. Therefore, immunity competes with other maintenance programmes for energy. The brain stem integrates the energy demand of each organ system, with immunity considered a top priority. The brain stem may "decide" to make a trade-off which involves the induction of a dormancy programme that permits the shutdown of mitochondrial respiration and oxidative phosphorylation in peripheral organs. In the context of acutely decompensated cirrhosis, the consequence of a shutdown of mitochondrial respiration and ATP production would be a dramatic decrease in organ function.

Management of Portal Hypertension in Patients with Acute-on-Chronic Liver Disease

Portal hypertension is central to the pathogenesis of complications of cirrhosis, including acute-on-chronic liver failure (ACLF). Both nonselective beta-blockers and preemptive transjugular portal-systemic stent shunt can lower portal pressure, reducing the risk of variceal bleeding, a known trigger for ACLF. However, in patients with advanced cirrhosis, both could potentially induce ACLF by causing hemodynamic instability and hepatic ischemia, respectively, and therefore must be used with caution. Lowering portal pressure with vasoconstrictor such as terlipressin can reverse the kidney failure but careful patient selection is key for success, with careful monitoring for complications.

Hepatic Encephalopathy in Cirrhotic Patients With Bacterial Infections: Frequency, Clinical Characteristics, and Prognostic Relevance

Background/Objectives

Bacterial infections (BIs) are well-recognized precipitants of hepatic encephalopathy (HE). Nevertheless, there is a paucity of data in patients with HE associated with BI. Our aim was to describe clinical characteristics, recurrence, and prognosis of HE in patients with BI.

Methods

A prospective study with inclusion of hospitalized cirrhotic patients with BI, followed until discharge, death, or liver transplantation.

Results

172 patients (age 57 ± 13, model of end-stage liver disease [MELD]-sodium 22 ± 8) were included. Infections were more commonly due to spontaneous bacterial peritonitis and cellulitis (22% and 23%), non-nosocomial (70%), and associated with systemic inflammatory response syndrome and septic shock in 40% and 9%, respectively. HE was diagnosed in 66 patients (grade ≥2 in 58%). In multivariate analysis, MELD-sodium, albumin, and prior HE were associated with HE at diagnosis of BI. Recurrence of HE was diagnosed in 30 patients (median 13 [interquartile range 5-22] days), more commonly manifested as overt HE (90% vs. 60% at first episode, P = 0.012) and more frequently in patients with hyponatremia (54% vs. 27% for patients without, P < 0.001). In-hospital mortality was 34% and was more common for patients with HE (51% vs. 22%, P < 0.001), irrespective of grade, and for those with recurrence (63% vs. 42%, P < 0.001). In multivariate analysis, HE at diagnosis of infection and MELD-sodium were predictors of mortality.

Conclusions

HE is frequent in cirrhotic patients with BI and is associated with severity of liver disease, but not with infection. These patients are at increased risk of short-term HE recurrence, especially those with hyponatremia. The presence and recurrence of HE, independent of severity, are associated with in-hospital mortality.

Infection prevention and control programme and COVID-19 measures: Effects on hospital-acquired infections in patients with cirrhosis

Background & Aims

Bacterial infections affect survival of patients with cirrhosis. Hospital-acquired bacterial infections present a growing healthcare problem because of the increasing prevalence of multidrug-resistant organisms. This study aimed to investigate the impact of an infection prevention and control programme and coronavirus disease 2019 (COVID-19) measures on the incidence of hospital-acquired infections and a set of secondary outcomes, including the prevalence of multidrug-resistant organisms, empiric antibiotic treatment failure, and development of septic states in patients with cirrhosis.

Methods

The infection prevention and control programme was a complex strategy based on antimicrobial stewardship and the reduction of patient's exposure to risk factors. The COVID-19 measures presented further behavioural and hygiene restrictions imposed by the Hospital and Health Italian Sanitary System recommendations. We performed a combined retrospective and prospective study in which we compared the impact of extra measures against the hospital standard.

Results

We analysed data from 941 patients. The infection prevention and control programme was associated with a reduction in the incidence of hospital-acquired infections (17 vs. 8.9%, p <0.01). No further reduction was present after the COVID-19 measures had been imposed. The impact of the infection prevention and control programme remained significant even after controlling for the effects of confounding variables (odds ratio 0.44, 95% CI 0.26-0.73, p = 0.002). Furthermore, the adoption of the programme reduced the prevalence of multidrug-resistant organisms and decreased rates of empiric antibiotic treatment failure and the development of septic states.

Conclusions

The infection prevention and control programme decreased the incidence of hospital-acquired infections by nearly 50%. Furthermore, the programme also reduced the prevalence of most of the secondary outcomes. Based on the results of this study, we encourage other liver centres to adopt infection prevention and control programmes.

Impact and implications

Infections are a life-threatening problem for patients with liver cirrhosis. Moreover, hospital-acquired infections are even more alarming owing to the high prevalence of multidrug-resistant bacteria. This study analysed a large cohort of hospitalised patients with cirrhosis from three different periods. Unlike in the first period, an infection prevention programme was applied in the second period, reducing the number of hospital-acquired infections and containing multidrug-resistant bacteria. In the third period, we imposed even more stringent measures to minimise the impact of the COVID-19 outbreak. However, these measures did not result in a further reduction in hospital-acquired infections.

Therapeutic possibilities of gut microbiota modulation in acute decompensation of liver cirrhosis

The formation of liver cirrhosis (LC) is an unfavorable event in the natural history of chronic liver diseases and with the development of portal hypertension and/or impaired liver function can cause a fatal outcome. Decompensation of LC is considered the most important stratification variable for the risk of death. It is currently postulated that decompensation of LC occurs through an acute (including acute-on-chronic liver failure) and non-acute pathway. Acute decompensation of LC is accompanied by the development of life-threatening complications, characterized by an unfavorable prognosis and high mortality. Progress in understanding the underlying molecular mechanisms has led to the search for new interventions, drugs, and biological substances that can affect key links in the pathogenesis of acute decompensation in LC, for example the impaired gut-liver axis and associated systemic inflammation. Given that particular alterations in the composition and function of gut microbiota play a crucial role here, the study of the therapeutic possibilities of its modulation has emerged as one of the top concerns in modern hepatology. This review summarized the investigations that describe the theoretical foundations and therapeutic potential of gut microbiota modulation in acute decompensation of LC. Despite the encouraging preliminary data, the majority of the suggested strategies have only been tested in animal models or in preliminary clinical trials; additional multicenter randomized controlled trials must demonstrate their efficacy in larger patient populations.

Gut Microbiota and Infectious Complications in Advanced Chronic Liver Disease: Focus on Spontaneous Bacterial Peritonitis

Liver cirrhosis is a chronic disease that can be complicated by episodes of decompensation such as variceal bleeding, hepatic encephalopathy, ascites, and jaundice, with subsequent increased mortality. Infections are also among the most common complications in cirrhotic patients, mostly due to a defect in immunosurveillance. Among them, one of the most frequent is spontaneous bacterial peritonitis (SBP), defined as the primary infection of ascitic fluid without other abdominal foci. SBP is mainly induced by Gram-negative bacteria living in the intestinal tract, and translocating through the intestinal barrier, which in cirrhotic patients is defective and more permeable. Moreover, in cirrhotic patients, the intestinal microbiota shows an altered composition, poor in beneficial elements and enriched in potentially pathogenic ones. This condition further promotes the development of leaky gut and increases the risk of SBP. The first-line treatment of SBP is antibiotic therapy; however, the antibiotics used have a broad spectrum of action and may adversely affect the composition of the gut microbiota, worsening dysbiosis. For this reason, the future goal is to use new therapeutic agents that act primarily on the gut microbiota, selectively modulating it, or on the intestinal barrier, reducing its permeability. In this review, we aim to describe the reciprocal relationship between gut microbiota and SBP, focusing on pathogenetic aspects but also on new future therapies.

Challenges and recommendations when selecting empirical antibiotics in patients with cirrhosis

There is abundant evidence that bacterial infections are severe complications in patients with cirrhosis, being the most frequent trigger of acute-on-chronic liver failure and causing death in one of every four patients during hospitalization. For these reasons, early diagnosis and effective treatment of infections are mandatory to improve patient outcomes. However, treating physicians are challenged in daily practice since diagnosing bacterial infections is not always straightforward. This situation might lead to delayed antibiotic initiation or prescription of ineffective regimens, which are associated with poor outcomes. On the other hand, prescribing broad-spectrum antibiotics to all patients suspected of bacterial infections might favor bacterial resistance development. This is a significant concern given the alarming number of infections caused by multidrug-resistant microorganisms worldwide. Therefore, it is paramount to know the local epidemiology to propose tailored guidelines for empirical antibiotic selection in patients with cirrhosis in whom bacterial infections are suspected or confirmed. In this article, we will revise current knowledge in this area and highlight the importance of surveillance programs.

An Overview of Drug Delivery Nanosystems for Sepsis-Related Liver Injury Treatment

Sepsis, which is a systemic inflammatory response syndrome caused by infection, has high morbidity and mortality. Sepsis-related liver injury is one of the manifestations of sepsis-induced multiple organ syndrome. To date, an increasing number of studies have shown that the hepatic inflammatory response, oxidative stress, microcirculation coagulation dysfunction, and bacterial translocation play extremely vital roles in the occurrence and development of sepsis-related liver injury. In the clinic, sepsis-related liver injury is mainly treated by routine empirical methods on the basis of the primary disease. However, these therapies have some shortcomings, such as serious side effects, short duration of drug effects and lack of specificity. The emergence of drug delivery nanosystems can significantly improve drug bioavailability and reduce toxic side effects. In this paper, we reviewed drug delivery nanosystems designed for the treatment of sepsis-related liver injury according to their mechanisms (hepatic inflammation response, oxidative stress, coagulation dysfunction in the microcirculation, and bacterial translocation). Although much promising progress has been achieved, translation into clinical practice is still difficult. To this end, we also discussed the key issues currently facing this field, including immune system rejection and single treatment modalities. Finally, with the rigorous optimization of nanotechnology and the deepening of research, drug delivery nanosystems have great potential for the treatment of sepsis-related liver injury.

A Pathogenic Role of Non-Parenchymal Liver Cells in Alcohol-Associated Liver Disease of Infectious and Non-Infectious Origin

Now, much is known regarding the impact of chronic and heavy alcohol consumption on the disruption of physiological liver functions and the induction of structural distortions in the hepatic tissues in alcohol-associated liver disease (ALD). This review deliberates the effects of alcohol on the activity and properties of liver non-parenchymal cells (NPCs), which are either residential or infiltrated into the liver from the general circulation. NPCs play a pivotal role in the regulation of organ inflammation and fibrosis, both in the context of hepatotropic infections and in non-infectious settings. Here, we overview how NPC functions in ALD are regulated by second hits, such as gender and the exposure to bacterial or viral infections. As an example of the virus-mediated trigger of liver injury, we focused on HIV infections potentiated by alcohol exposure, since this combination was only limitedly studied in relation to the role of hepatic stellate cells (HSCs) in the development of liver fibrosis. The review specifically focusses on liver macrophages, HSC, and T-lymphocytes and their regulation of ALD pathogenesis and outcomes. It also illustrates the activation of NPCs by the engulfment of apoptotic bodies, a frequent event observed when hepatocytes are exposed to ethanol metabolites and infections. As an example of such a double-hit-induced apoptotic hepatocyte death, we deliberate on the hepatotoxic accumulation of HIV proteins, which in combination with ethanol metabolites, causes intensive hepatic cell death and pro-fibrotic activation of HSCs engulfing these HIV- and malondialdehyde-expressing apoptotic hepatocytes.

Epidemiology of liver cirrhosis and associated complications: Current knowledge and future directions

Cirrhosis causes a heavy global burden. In this review, we summarized up-to-date epidemiological features of cirrhosis and its complications. Recent epidemiological studies reported an increase in the prevalence of cirrhosis in 2017 compared to in 1990 in both men and women, with 5.2 million cases of cirrhosis and chronic liver disease occurring in 2017. Cirrhosis caused 1.48 million deaths in 2019, an increase of 8.1% compared to 2017. Disability-adjusted life-years due to cirrhosis ranked 16th among all diseases and 7th in people aged 50-74 years in 2019. The global burden of hepatitis B virus and hepatitis C virus-associated cirrhosis is decreasing, while the burden of cirrhosis due to alcohol and nonalcoholic fatty liver disease (NAFLD) is increasing rapidly. We described the current epidemiology of the major complications of cirrhosis, including ascites, variceal bleeding, hepatic encephalopathy, renal disorders, and infections. We also summarized the epidemiology of hepatocellular carcinoma in patients with cirrhosis. In the future, NAFLD-related cirrhosis will likely become more common due to the prevalence of metabolic diseases such as obesity and diabetes, and the prevalence of alcohol-induced cirrhosis is increasing. This altered epidemiology should be clinically noted, and relevant interventions should be undertaken.

Suppressed serological vitamin A in patients with liver cirrhosis is associated with impaired liver function and clinical detoriation

BACKGROUND

The liver is of critical importance for the homeostasis of metabolic and immunomodulatory properties as well as the storage of vitamins, especially vitamin A. In this prospective analysis, the incidence of serological vitamin A deficiency and the association with disease severity as well as clinical complications in patients with liver cirrhosis were investigated.

METHOD

From May 2017 to May 2018, 159 patients with primarily alcohol-associated and non-alcoholic steatohepatitis (NASH)-associated preexisting liver cirrhosis were prospectively enrolled and vitamin A status was collected. Clinical complications and infections were followed and recorded over a period of 1-year follow-up. Selected findings were validated in an independent cohort of 44 patients.

RESULTS

At study inclusion, 77% of patients showed decreased serological vitamin A. Suppressed vitamin A was more common in alcoholic (52 vs. 8%) and NASH-associated liver cirrhosis (16 vs. 9%) than in viral-associated liver cirrhosis. MELD score as well as Child-Pugh score were significantly associated with suppressed vitamin A ( P  < 0.001). The association between the degree of vitamin A suppression and liver function was confirmed in univariate and multivariate regression analysis. After 1 year of follow-up, 57 patients died and 21 patients received a liver transplant. In addition, low vitamin A levels were more commonly observed in patients with severe ascites ( P  = 0.001), hepatic encephalopathy ( P  = 0.002) and hepatorenal syndromes ( P  = 0.008). In addition, patients with reduced vitamin A showed an increased incidence of infections ( P  = 0.02), especially respiratory infections ( P  = 0.04).

CONCLUSION

Suppressed serological Vitamin A is common in patients with liver cirrhosis and is associated with liver function. Clinical complications and infections are more frequent in patients with liver cirrhosis and vitamin A suppression.

The neutrophil-to-lymphocyte ratio represents a systemic inflammation marker and reflects the relationship with 90-day mortality in non-cirrhotic chronic severe hepatitis

OBJECTIVES

To investigate the relationship between systemic inflammatory response and short-term mortality in patients with non-cirrhotic chronic severe hepatitis (CSH) by using several indicators of inflammation including neutrophil-to-lymphocyte ratio (NLR), neutrophil (NEU), white blood cell (WBC), platelet-to lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR).

METHODS

Data were collected from two prospectively enrolled CATCH-LIFE noncirrhotic cohorts. Cox regression analysis was used to investigate the association between systemic inflammatory biomarkers and 90-day liver transplant (LT)-free mortality. A generalized additive model (GAM) was used to illustrate the quantitative curve relationship between NLR and 90-day LT-free mortality. Kaplan-Meier method was used to estimate the 90-year LT-free survival.

RESULTS

The prevalence of CSH was 20.5% (226/1103). The 28-day and 90-day LT-free mortality rates were 17.7% and 26.1%, respectively, for patients with non-cirrhotic CSH. Patients with no infection accounted for 75.0% of all CSH patients, and NLR was independently associated with 90-day LT-free mortality. NLR of 2.9 might be related to disease deterioration in CSH patients without infection.

CONCLUSIONS

NLR may be an independent risk factor for 90-day LT-free mortality in patients with non-cirrhotic chronic liver disease. A NLR of 2.9 as the cut-off value can be used to predict disease aggravation in CSH patients without infection.

The gut-liver axis in immune remodeling of hepatic cirrhosis

In healthy settings, the gut-liver axis allows host-microbiota communications and mediates immune homeostasis through bidirectional regulation. Meanwhile, in diseases, gut dysbiosis, combined with an impaired intestinal barrier, introduces pathogens and their toxic metabolites into the system, causing massive immune alternations in the liver and other extrahepatic organs. Accumulating evidence suggests that these immune changes are associated with the progression of many liver diseases, especially hepatic cirrhosis. Pathogen-associated molecular patterns that originated from gut microbes directly stimulate hepatocytes and liver immune cells through different pattern recognition receptors, a process further facilitated by damage-associated molecular patterns released from injured hepatocytes. Hepatic stellate cells, along with other immune cells, contribute to this proinflammatory and profibrogenic transformation. Moreover, cirrhosis-associated immune dysfunction, an imbalanced immune status characterized by systemic inflammation and immune deficiency, is linked to gut dysbiosis. Though the systemic inflammation hypothesis starts to link gut dysbiosis to decompensated cirrhosis from a clinical perspective, a clearer demonstration is still needed for the role of the gut-liver-immune axis in cirrhosis progression. This review discusses the different immune states of the gut-liver axis in both healthy and cirrhotic settings and, more importantly, summarizes the current evidence about how microbiota-derived immune remodeling contributes to the progression of hepatic cirrhosis via the gut-liver axis.

Mesenchymal Stem Cell Transplantation in Liver Diseases

Promising preclinical data suggested that bone marrow-derived mesenchymal stem cells (BM-MSC) can reduce hepatic fibrosis and stimulate liver regeneration. Preclinical studies moreover suggested that the immunomodulatory and anti-inflammatory functions of MSCs may reduce hepatic inflammation, improve liver function, and decrease infection incidences which are deemed especially important in the case of acute-on-chronic liver failure (ACLF). Studies in patients with decompensated cirrhosis demonstrated that injection of BM-MSC resulted in an improvement of biochemical tests and led to a survival benefit in ACLF. Most of these studies were performed in hepatitis B virus infected patients. However, two adequately powered studies performed in Europe could not confirm these data. A possible alternative to mobilize BM-MSC into the liver is the use of granulocyte colony-stimulating factor (G-CSF) which has proregenerative and immunomodulatory effects. In Indian studies, the use of G-CSF was associated with improvement of survival, although this finding could not be confirmed in European studies. Human allogeneic liver-derived progenitor cell therapy represents a potential treatment for ACLF, of which the main action is paracrine. These human liver-derived MSC can perform various functions, including the downregulation of proinflammatory responses. The clinical beneficial effect of these cells is further explored in patients with alcoholic cirrhosis and ACLF in Europe.

Plasticity of monocytes and macrophages in cirrhosis of the liver

Cirrhosis of the liver is a systemic condition with raising prevalence worldwide. Patients with cirrhosis are highly susceptible to develop bacterial infections leading to acute decompensation and acute-on-chronic liver failure both associated with a high morbidity and mortality and sparse therapeutic options other than transplantation. Mononuclear phagocytes play a central role in innate immune responses and represent a first line of defence against pathogens. Their function includes phagocytosis, killing of bacteria, antigen presentation, cytokine production as well as recruitment and activation of immune effector cells. Liver injury and development of cirrhosis induces activation of liver resident Kupffer cells and recruitment of monocytes to the liver. Damage- and pathogen-associated molecular patterns promote systemic inflammation which involves multiple compartments besides the liver, such as the circulation, gut, peritoneal cavity and others. The function of circulating monocytes and tissue macrophages is severely impaired and worsens along with cirrhosis progression. The underlying mechanisms are complex and incompletely understood. Recent 'omics' technologies help to transform our understanding of cellular diversity and function in health and disease. In this review we point out the current state of knowledge on phenotypical and functional changes of monocytes and macrophages during cirrhosis evolution in different compartments and their role in disease progression. We also discuss the value of potential prognostic markers for cirrhosis-associated immuneparesis, and future immunotherapeutic strategies that may reduce the need for transplantation and death.

Clostridioides difficile Infection in Liver Cirrhosis: A Concise Review

Clostridium difficile is a Gram-positive bacillus with fecal-oral transmission and is currently one of the most common nosocomial infections worldwide, which was renamed Clostridioides difficile in 2016. Clostridioides difficile infection (CDI) is a prevalent infection in cirrhosis and negatively affects prognosis. This study aimed to provide a concise review with clinical practice implications. The prevalence of CDI in cirrhotic patients increases, while the associated mortality decreases. Multiple groups of risk factors increase the likelihood of CDI in patients with cirrhosis, such as antibiotic use, the severity of cirrhosis, some comorbidities, and demographic aspects. Treatment in the general population is currently described in the latest guidelines. In patients with cirrhosis, rifaximin and lactulose have been shown to reduce CDI risk due to their modulatory effects on the intestinal flora, although conflicting results exist. Fecal microbiota transplantation (FMT) as a treatment for the second or subsequent CDI recurrences has demonstrated a good safety and efficacy in cirrhosis and CDI. Future validation in more prospective studies is needed. Screening of asymptomatic patients appears to be discouraged for the prevention currently, with strict hand hygiene and cleaning of the ward and medical equipment surfaces being the cornerstone of minimizing transmission.

Decompensation of Cirrhosis: An Unusual Cause

We describe a case of a 69-year-old woman, a known case of compensated Hepatitis C cirrhosis, presenting with recurrent urinary tract infection (UTI) secondary to Salmonella Paratyphi B. She had recently tested positive for Salmonella Paratyphi bacteremia associated with UTI, managed with antibiotics. Two weeks later, she presented with fever and burning micturition with signs of abdominal distension and pedal edema suggestive of decompensation of cirrhosis. She had repeat positive urine cultures for Salmonella and was managed with broad-spectrum antibiotics, surgical stone removal, and supportive measures leading to resolution of symptoms and ascites. She was administered a prolonged antibiotic course on discharge for chronic shedding of Salmonella in the urine.

UTIs are a common cause of decompensation in immunosuppressed states like liver cirrhosis, and rare infections like salmonella need to be identified and managed appropriately with sensitive antibiotics and the right duration of treatment.

Inflammation in alcohol-associated liver disease progression

Chronic alcohol consumption induces stress and damage in alcohol metabolising hepatocytes, which leads to inflammatory and fibrogenic responses. Besides these direct effects, alcohol disrupts intestinal barrier functions and induces gut microbial dysbiosis, causing translocation of bacteria or microbial products through the gut mucosa to the liver and, which induce inflammation indirectly. Inflammation is one of the key drivers of alcohol-associated liver disease progression from steatosis to severe alcoholic hepatitis. The current standard of care for the treatment of severe alcoholic hepatitis is prednisolone, aiming to reduce inflammation. Prednisolone, however improves only short-term but not long-term survival rates in those patients, and even increases the risk for bacterial infections. Thus, recent studies focus on the exploration of more specific inflammatory targets for the treatment of severe alcoholic hepatitis. These comprise, among others interference with inflammatory cytokines, modulation of macrophage phenotypes or targeting of immune cell communication, as summarized in the present overview. Although several approaches give promising results in preclinical studies, data robustness and ability to transfer experimental results to human disease is still not sufficient for effective clinical translation.

Novel drug discovery strategies for the treatment of decompensated cirrhosis

INTRODUCTION

Disease progression in cirrhosis leads to decompensation and acute-on-chronic liver failure (ACLF), which is characterized by organ failure and high mortality. Portal hypertension and cardiovascular dysfunction trigger the development of cirrhosis-related complications whilst tissue injury and cellular metabolic dysfunction lead to organ failure. System inflammation is the overarching mechanism mediating both the transition from compensation to decompensation as well as progression to ACLF. Treatment of precipitating events and intensive organ support is the only established therapeutic strategies. Liver transplantationrepresents the only curative therapy but contraindications and organ scarcity limit its availability to only a minority of patients with end-stage liver disease. Therefore, the discovery and development of novel interventions modifying the disease course and improving patients' outcome are of utmost importance.

AREAS COVERED

This review highlights and discusses therapeutic novelties in the field of end-stage liver disease.

EXPERT OPINION

Despite decades of research, there are still no established therapies to improve the devastating prognosis of patients with end-stage liver disease. The clinical heterogeneity and complex pathogenesis will put high demands on drug discovery. Combinatorial therapies tailored to the patients' individual pattern of pathomechanisms may be the most efficient way to modify disease course.

Si-Wu-Tang ameliorates fibrotic liver injury via modulating intestinal microbiota and bile acid homeostasis

Background

Fibrotic liver injury is a progressive scarring event, which may permanently affect liver function and progress into devastating end-stage liver diseases due to the absence of effective therapies. Si-Wu-Tang (SWT), a traditional Chinese medicine formula used in clinic to treat gynecological disorders for centuries, has been investigated in recent preliminary findings for its role in alleviating chronic liver diseases. Here we aim to elucidate the therapeutic effects and possible mechanisms of SWT against fibrotic liver injury.

Methods

UHPLC-MS/MS was performed to investigate the chemical characterization of SWT. After intragastrically administered with carbon tetrachloride (CCl₄) every 3 days for 1-week, C57BL/6 mice were orally administered with SWT (5.2, 10.4 and 20.8 g/kg) once daily for 3 weeks along with CCl₄ challenge. Liver function was determined by the measurement of serum biomarkers, hematoxylin and eosin (H&E) and Masson’s trichrome staining. Intestinal inflammatory infiltration and the disruption of intestinal barrier were examined by H&E and E-cadherin immunohistochemical staining. The microbial composition of intestinal content was determined by 16S rRNA sequencing. Serum bile acids (BAs) profiling was analyzed by LC–MS/MS. Simultaneously, the expression of genes of interest was determined by qPCR and western blot.

Results

SWT exhibited remarkable therapeutic effects on CCl₄-induced liver fibrosis, as indicated by improved collagen accumulation in livers, intestinal barrier injury and hepatic and intestinal inflammatory response. Results of 16S rRNA sequencing revealed that SWT treatment strikingly restructured intestinal microbiota in fibrotic mice by increasing the relative abundances of Bacteroides and Lachnoclostridium and decreasing the relative abundances of Alistipes and Rikenellaceae. UHPLC-MS/MS data suggested that SWT altered the composition of BAs in circulation as evidenced by increased unconjugated BAs like cholic acid and chenodeoxycholic acid but decreased conjugated BAs including taurocholic acid and taurodeoxycholic acid, compared to that in CCl₄ mice. Notably, SWT efficiently improved the imbalance of BA homeostasis in livers caused by CCl₄ via activating farnesoid X receptor (FXR)-fibroblast growth factor 15 enterohepatic and FXR-small heterodimer partner hepatic pathways.

Conclusion

SWT decreased inflammatory response, reconstructed gut microbiota-mediated BA homeostasis as well as activated FXR pathways, which eventually protected against CCl₄-induced fibrotic liver injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00524-0.

Gut microbiota dysbiosis associated with plasma levels of Interferon-γ and viral load in patients with acute hepatitis E infection

Few studies have focused on the effect of hepatitis E virus (HEV) infection on gut microbiota. To explore the relationship between changes in gut microbiota and inflammatory factors and viral load, we conducted a comparative study of 33 patients with acute hepatitis E (AHE) patients and 25 healthy controls (HCs) using high-throughput 16S ribosomal ribonucleic acid gene sequencing. Shannon and Simpson's indices showed no significant differences in bacterial diversity between the AHE and HCs groups. Proteobacteria, Gammaproteobacteria, and Enterobacteriaceae were most abundant in the AHE group, which contributed to the difference between the gut microbiota of the AHE and HCs groups, and the same difference between the HEV-RNA-positive and HEV-RNA-negative groups. Functional prediction analysis showed that ribosome, purine metabolism, and two-component system were the top three pathways. Compared with the AHE group with normal interferon (IFN)-γ, Proteobacteria, Gammaproteobacteria, Xanthomonadaceae, and Enterobacteriaceae were more abundant in the high-IFN-γ group. The abundance of Gammaproteobacteria was positively correlated with the level of serum alanine transaminase and total bilirubin. The abundance of Gammaproteobacteria could discriminate AHE patients from HCs, and could better predict the severity of AHE patients. We believe that our findings will contribute toward a novel treatment strategy for AHE.