Cirrhosis is a late stage of hepatic fibrosis caused by many forms of liver diseases and conditions, such as hepatitis and chronic alcoholism. The World Health Organization (WHO) has reported that this condition accounts for 1.8% of all deaths in Europe (170,000 deaths/year).

Patients with cirrhosis are characterized by severe metabolic alterations, which converge in a malnutritional state. Malnutrition encompasses glucose intolerance, chronic inflammation, altered gut microbiota, reduced muscle mass (sarcopenia), as well as loss and dysregulation of adipose tissue (adipopenia). Malnutrition is the most frequent complication that adversely affects the outcomes of cirrhotic patients. Yet, despite its clinical repercussions and potential reversibility, there are no effective therapies because our limited understanding of the mechanisms underlying this altered metabolism.

β-hydroxy β-methylbutyrate (HMB) is a naturally produced substance regarded as safe and effective in preventing muscle loss during chronic diseases. Previous studies have indicated some beneficial effects of HMB itself or its parent metabolite, leucine, on adipose tissue, glucose intolerance, inflammation, and gut microbiota. This study aims to translate those beneficial effects to cirrhotic patients. The investigators hypothesize that HMB can improve cirrhosis-related metabolic abnormalities through its pleiotropic effects. The goals of this study are: i) to perform a randomized clinical trial to evaluate the efficacy of HMB, administered as nutritional supplementation, on clinical symptoms of cirrhosis.

ii) to uncover the precise metabolic pathways that underlie HMB action, with a special focus on muscle, adipose tissue, and gut microbiota.

1. Scientific & technical aspects

State of the art:

Patients with cirrhosis present a chronic inflammatory state and alterations in protein metabolism. These alterations lead to elevated levels of insulin and catecholamines along with the development of glucose intolerance and insulin resistance. The reduced availability of glucose as energy source translates into an accelerated starvation with reduced body fat mass (adipopenia) and loss of skeletal muscle mass (sarcopenia). This catabolic state reduces survival and post-liver transplant outcomes in patients with cirrhosis.

Loss of skeletal muscle mass or sarcopenia is the major component of malnutrition in cirrhosis and occurs in the majority of patients. Impaired ureagenesis and portosystemic shunting provoke skeletal muscle hyperammonemia which induces up-regulation of myostatin and increased autophagy, both of which contribute to sarcopenia.

The adipose tissue (AT) regulates energy homeostasis in the body regardless of the obesity status. Indeed, serum levels of the main adipose-produced cytokines (adipokines) such as leptin, adiponectin, and resistin have been found to be increased in cirrhotic patients as liver function worsens. Evidence demonstrated that adiponectin interacts with the immune/macrophage system and might be of relevance in many liver diseases. Likewise, hyperinsulinemia and increased tumor necrosis factor (TNF) α levels upregulated the adipose resistin gene in rat models of liver cirrhosis.

Recently, growing attention has been targeted to the gut microbiota (GM) in the pathogenesis of gastrointestinal diseases. GM constitutes a symbiotic ecosystem that keeps homeostatic balance within the human body producing a diverse range of compounds that have a major role in regulating the activity of distal organs. Recent studies have shown changes in the relative abundance of microbiota in the stool, colonic mucosa, and saliva of cirrhotic patients. Therefore, modulation of GM arises as a promising tool to prevent and/or to treat the development of these liver disorders.

Clinical guidelines recommend to provide adequate amounts of calories and proteins to cirrhotic patients, either by frequent feeding or via diet supplementation. Consequently, different high caloric diets have been extensively studied. Yet, few studies have shown significant benefit of this type of diets in malnourished cirrhotic patients. Protein supplementation may improve the availability of essential amino acids. However, animal proteins are enriched in aromatic amino acids that are not metabolized by the skeletal muscle and may worsen encephalopathy. Alternatively, modifying the source of nitrogen by using more vegetable protein, less animal protein, and/or branched-chain aminoacids (BCAA) supplementation may help prevent encephalopathy, sarcopenia and adipopenia. Yet, a recently published Cochrane review showed that BCAA did have a beneficial effect on hepatic encephalopathy, but found no effect on mortality, quality of life, or nutritional parameters. This absence of benefit in nutritional parameters might be counter intuitive, as BCAA provide a source of energy to the muscle in addition to being substrates for protein synthesis. The investigators hypothesize that beneficial effects associated to BCAA are, at least partially, mediated by some product/s of their metabolism, likely formed by hepatic synthesis. The cirrhosis-associated liver damage would be hence impeding their synthesis. As consequence, to obtain the expected beneficial outcomes of the BCAA ingestion there should be an increase of the supplemented BCAA or a direct supplementation of the active metabolite/s.

b. Objectives HMB is produced from leucine and is one of its most active metabolites. The majority of HMB production occurs in the liver. Since the mid-1990s, a large body of studies have described that HMB is safe and effective in preventing muscle loss during chronic diseases. Moreover, recent studies have also indicated effects of HMB itself or its parent metabolite, leucine, on adipose tissue differentiation, glucose intolerance, inflammation, gut microbiota, and inflammation reduction. All these beneficial properties make HMB an ideal candidate to supplement the diet of individuals with cirrhosis, a hypothesis that will be tested in the current study. Thus, the specific aim of this proposal is to perform a randomized clinical trial to evaluate the efficacy of HMB, administered as nutritional supplementation, on clinical symptoms of cirrhosis. The study will be performed in adult individuals with cirrhosis. Power analyses based on previously described variations in muscle mass were calculated using R software. The required sample size per group for a power level of 0.9 is estimated to be n = 30,

Inclusion Criteria:

1. negative for hepatitis C virus (HCV)&hepatitis B virus (HBV) , or alcohol-caused cirrhosis in stable clinical condition,
2. alcoholic patients must have been abstinent for at least 6 months and be in Child's score of ≤7,
3. no gastrointestinal bleeding for at least 3 months,
4. no clinical, microbiological, or laboratory evidence of infection, renal failure, encephalopathy, malignancy, diabetes mellitus, comorbidities including heart failure or pulmonary disease,
5. No use of medications that affect protein turnover, including corticosteroids and β-blockers.

Exclusion Criteria:

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