What challenge is GALAXY adressing?
Alcohol overuse is the leading cause of cirrhosis, a disease with poor prognosis due to late diagnosis and sparse treatment options. Claiming more than 500,000 lives/year globally, alcohol-related liver disease (ALD) represents a huge unmet social challenge due to the high morbidity associated with the disease. ALD covers a disease spectrum from simple fat accumulation in the liver, over inflammation to progressive accumulation of scar tissue leading to cirrhosis. Available treatments are lifestyle interventions; however, they are insufficient due to limited efficacy, frequent failure and poor compliance. Current available pharmacological treatments have limited effects.
GALAXY hypothesis
GALAXY aims at understanding the key networks in the development and progression of ALD, to identify and test novel drug targets and describe the socioeconomic burden of the disease. The hypothesis is that gut bacterial composition determines susceptibility to liver disease and that cross talk between the gut microbiome and the liver drives the disease progression. As liver fibrosis is associated with a “bacterial gut imbalance”, targeting the gut-liver-axis, may represent a target for reversing scar accumulation. But ALD is a complex, multifactorial disease, in which no individual factors can explain disease phenotype. GALAXY explores the inter-dependencies between the individual host, the gut and the liver, by using a systems medicine approach. This allows us to integrate extensive phenotypic data from the individual patients with characteristics of the patients´ genome and gut microbiome. Ultimately, this leads to optimized personalized healthcare, by stratifying individuals who would benefit from targeted healthcare efforts, and thus reduce the economic burden for health care systems and to improve health outcome for the patients.
GALAXY objectives
- Identify signatures of host-microbial cross-talk during disease development and progression.
- Translate this into biomarkers for diagnosis, stratification and treatment monitoring in patients with an excess use of alcohol.
- Verify discovered key networks in animal models and validate biomarkers in an interventional clinical study.
- Evaluate interventions based on microbiome modulation to prevent ALF progression.
Conclusion
Our conclusion of the action is that gut bacteria in a cross talk with the person’s liver, genetics and other traits determines an individual’s susceptibility to liver disease. This knowledge is used to develop and validate new diagnostic and prognostic tests, and for novel interventions which attenuates disease progression by seeking to reverse a dysbalanced microbiome. For the four objectives listed above, here we describe the work performed and main results.
1. Identification of gut-liver axis during development and progression of ALD
For this purpose, we used a study of 461 patients with ALD and a study of 148 healthy participants matched for age, gender and BMI (partly) with the ALD study. We mapped the microbiome taxonomy and transcription of microbial genes. We then correlated these measurements with histological liver lesions, and patient outcomes. This work has led os to identify specific changes to the microbiome during progression of ALD. First, we found that the microbiome diversity is stepwise reduced from a healthy gut microbiome to increasingly lower diversity in early and advanced ALD. Second, we found differences in certain microbial species between patients with severe ALD and healthy people or early ALD. One of these species where not only less abundant in ALD patients, its expression of genes (the bacterium’s activity) were also significantly altered.
2. Biomarkers for diagnosis, prognosis and monitoring in patients with excess use of alcohol
GALAXY’s biomarker work has been two-fold: First we validated best-in-class markers of liver fibrosis, liver inflammation, and the prediction of liver-related morbidity and mortality, because the existing markers had only been scarcely investigated in ALD. Second, we developed novel biomarkers based on omics technologies and on markers of collagen formation and degradation.
Until now, the GALAXY project has resulted in 13 scientific publications describing the diagnostic and prognostic accuracy of different biomarkers in ALD. We have several manuscripts in preparation describing the development of omics based biomarkers with high accuracy for diagnosis of fibrosis, inflammation and steatosis in ALD, and with excellent prognostic accuracy for all-cause mortality and occurrence of liver-related events.
3. Verify findings in animal models of ALD, and validate novel biomarkers in interventional study
GALAXY combined clinical studies in humans with investigations in animal models, for an in-depth understanding of the mechanisms driving chronic ALD. First, we developed an animal model that mimic human alcohol-related liver disease with fibrosis progression (PMID: 31188634). Next, we studied different aspects of disease progression in animals and human liver samples from cirrhosis patients and controls, to identify novel therapeutic targets. We explored the molecular mechanisms of how collagen accumulates in the liver as a result of alcohol-induced damage. These explorations included endocrine regulation by the Renin-Angiotensin-System, differences in the pattern by which different types of collagens accumulate in the liver, and the role of the innate immune system. Finally, we manipulated the gut-microbiome with Rifaximin, a gut-selective antibiotic, and compared its effects between our mouse models of ALD, and models of toxic and non-alcoholic fatty liver disease. Our data suggests different effects of rifaximin (RFX) depending on the etiology of liver disease.
We have measured our omics-based biomarkers and collagen biomarkers in two interventional studies – GAB-ALD and SYN-ALD – but not yet published results on the validation of biomarkers for monitoring the effect of treatment.
4. Evaluate interventions based on microbiome modulation to prevent progression of alcohol-related liver fibrosis
GAB-ALD and SYN-ALD tested the effect on ALD, when modulating the microbiome. Assessment of liver biopsies are the primary endpoint in both studies. Analysis of the microbiome, other omics, and biomarkers are currently under analysis.
In GAB-ALD we randomised 136 patients 1:1 to Rifaximin, or matching placebo. The protocol is published (DOI: 10.1186/s13063-018-2523-9). The study completed its last-patient-last-visit in Nov 2021. SYN-ALD randomised 56 patients with advanced ALD 1:1 to Fresubin or Profermin. Fresubin is a high-caloric liquid food for medical purposes. Profermin consists of fermented oat by Lactobacillus plantarum 299v, it is believed to improve the composition and activity of a dysbalanced microbiome. The study completed its last-patient-last-visit in Aug 2021, and we received results for the primary endpoint (attenuation of liver hepatic stellate cell activity) in Dec 2021.
Progress beyond state-ot-the-art
GALAXY is the first project to explore the inter-dependencies between the individual host, the gut and the liver, by using a systems medicine approach and measurement of so-called omics in stool, liver, urine, and blood: Genomics, metabolomics, lipidomics, transcriptomics, proteomics, and the microbiome – metagenomics and metatranscriptomics. We combined four high-quality studies in humans with animal models of liver disease. We also collected data on all the best available tests of liver fibrosis and liver disease severity, to compare any new tests with the existing best-in-class.
In conclusion, our combined efforts generated new pathophysiological knowledge of the role of the gut-liver-axis in alcohol-related liver disase, allowed the development and validation of accurate diagnostic and prognostic biomarkers, and novel treatment options. These results have substantially improved the care and management of patients with alcohol-related liver disease.
We report directly exploitable results. Most notably, Nordic Bioscience received a Letter of Intent from FDA for their patented biomarker ProC3, where GALAXY results were part of the application. We also currently evaluate one possible biomarker for patentability. Our biomarker efforts also included conducting a health-economics analysis of the cost-benefit of screening for alcohol-related liver disease in the population. We now use the database of costs and utilities to predict the cost-benefit of future interventions and biomarkers targeting ALD.