Microbiota and viral hepatitis: State of the art of a complex matter

Abstract

Changes in gut microbiota influence both the gut and liver, which are strictly connected by the so-called “gut–liver axis”. The gut microbiota acts as a major determinant of this relationship in the onset and clinical course of liver diseases. According to the results of several studies, gut dysbiosis is linked to viral hepatitis, mainly hepatitis C virus and hepatitis B virus infection. Gut bacteria-derived metabolites and cellular components are key molecules that affect liver function and modulate the pathology of viral hepatitis. Recent studies showed that the gut microbiota produces various molecules, such as peptidoglycans, lipopolysaccharides, DNA, lipoteichoic acid, indole-derivatives, bile acids, and trimethylamine, which are translocated to the liver and interact with liver immune cells causing pathological effects. Therefore, the existence of crosstalk between the gut microbiota and the liver and its implications on host health and pathologic status are essential factors impacting the etiology and therapeutic approach. Concrete mechanisms behind the pathogenic role of gut-derived components on the pathogenesis of viral hepatitis remain unclear and not understood. In this review, we discuss the current findings of research on the bidirectional relationship of the components of gut microbiota and the progression of liver diseases and viral hepatitis and vice versa . Moreover, this paper highlights the current therapeutic and preventive strategies, such as fecal transplantation, used to restore the gut microbiota composition and so improve host health.

The microbiome in post-acute infection syndrome (PAIS)

“…The biological interpretation of the differences is still unknown, but it can be crucial knowledge towards deciphering the association between infection and the microbiome. Additionally, consistent changes in the gut microbiota have been reported in patients with chronic infectious diseases like HIV [33] , HBV [34] , and TB [35] , which also lead to a reduction in microbial diversity and depletion of certain key bacterial species. Notably, specific changes observed in the microbiome may just reflect the complexity of conducting research, as variations in sample size, recruitment criteria, subject population, medical treatment, and methods for microbial classification can lead to varied conclusions.…”

“…2 The major taxa alterations in the gut bacteriome of acute infections, chronic infections and PAIS patients. Comparing to healthy controls, the major altered bacterial taxa identified in COVID-19 [27] , [28] , [29] , H1N1 [31] , H7N9 [32] , CAP (Community-Acquired Pneumonia) [29] , Dengue [39] , RSV (Respiratory Syncytial Virus) [38] , HIV (Human Immunodeficiency Virus) [33] , HBV (Hepatitis-B Virus) [34] , TB (Tuberculosis) [35] , PASC (Post-acute Sequelae of COVID-19) [25] , [40] , [41] , [42] , ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) [43] , [44] , [45] and PTLDS (Post-Treatment Lyme Disease Syndrome) [46] patients are listed in the figure. All the studies mentioned primarily focused on the gut bacteriome, except for the Dengue infection study, which was centered on the blood bacteriome …”

Alterations of the gut microbiota associated with the occurrence and progression of viral hepatitis

“…Changes in the abundance of some gut bacteria can lead to the secretion of anti-inflammatory factors, thus accelerating disease progression ( Peng et al., 2022 ). Moreover, gut microbiome-derived metabolites such as LPS and bile acids could interact with liver immune cells leading to pathological effects ( Milosevic et al., 2021 ). However, the existing research could not identify consistent microbial taxa that respond to the disease ( Wang et al., 2017 ; Chen et al., 2020 ).…”

Intestinal flora plays a role in the progression of hepatitis-cirrhosis-liver cancer

“…IgA can regulate the composition and abundance of intestinal microbiome, so reduced IgA secretion leads to increased abundance of Prevotella and other intestinal flora structure and function disorders. In addition, reduced IgA secretion increases intestinal permeability, leading to increased bacterial translocation ( Mantis et al., 2011 ; Milosevic et al., 2021 ). It has also been suggested that Lactobacillus acidophilus and Bifidobacterium can be used as a complementary treatment to effectively reduce LPS in patients with hepatitis C. Lactitol is known as a prebiotic, and Chen et al.…”