Microbiota-Liver Diseases Interactions.

Gut microbiota regulates essential processes of host metabolism and physiology: synthesis of vitamins, digestion of foods non-digestible by the host (such as fibers), and-most important-protects the digestive tract from pathogens. In this study, we focus on the CRISPR/Cas9 technology, which is extensively used to correct multiple diseases, including liver diseases. Then, we discuss the non-alcoholic fatty liver disease (NAFLD), affecting more than 25% of the global population; colorectal cancer (CRC) is second in mortality. We give space to rarely discussed topics, such as pathobionts and multiple mutations. Pathobionts help to understand the origin and complexity of the microbiota. Since several types of cancers have as target the gut, it is vital extending the research of multiple mutations to the type of cancers affecting the gut-liver axis.

Epigenetics and Helicobacter pylori.

Epigenetics regulates gene expression, cell type development during differentiation, and the cell response to environmental stimuli. To survive, bacteria need to evade the host immune response. Bacteria, including Helicobacter pylori (Hp), reach this target epigenetically, altering the chromatin of the host cells, in addition to several more approaches, such as DNA mutation and recombination. This review shows that Hp prevalently silences the genes of the human gastric mucosa by DNA methylation. Epigenetics includes different mechanisms. However, DNA methylation persists after DNA replication and therefore is frequently associated with the inheritance of repressed genes. Chromatin modification can be transmitted to daughter cells leading to heritable changes in gene expression. Aberrant epigenetic alteration of the gastric mucosa DNA remains the principal cause of gastric cancer. Numerous methylated genes have been found in cancer as well as in precancerous lesions of Hp-infected patients. These methylated genes inactivate tumor-suppressor genes. It is time for us to complain about our genetic and epigenetic makeups for our diseases.

Role of Branched-Chain Amino Acid Metabolism in Type 2 Diabetes, Obesity, Cardiovascular Disease and Non-Alcoholic Fatty Liver Disease.

Branched-chain amino acids (BCAAs) include leucine, isoleucine, and valine. Mammalians cannot synthesize these amino acids de novo and must acquire them through their diet. High levels of BCAAs are associated with insulin resistance; type 2 diabetes; obesity; and non-metabolic diseases, including several forms of cancer. BCAAs-in particular leucine-activate the rapamycin complex1 mTORC1, which regulates cell growth and metabolism, glucose metabolism and several more essential physiological processes. Diets rich in BCAAs are associated with metabolic diseases (listed above), while diets low in BCAAs are generally reported to promote metabolic health. As for the dysregulation of the metabolism caused by high levels of BCAAs, recent studies propose that the accumulation of acyl-carnitine and diacyl-CoA in muscles alters lipid metabolism. However, this suggestion is not broadly accepted. On clinical grounds, pre- and post-operative metabolic profiles of candidate patients for bariatric surgery are being used to select the optimal procedure for each individual patient.

Gut Microbiota Host-Gene Interaction.

Studies carried out in the last ten years have shown that the metabolites made up from the gut microbiota are essential for multiple functions, such as the correct development of the immune system of newborns, interception of pathogens, and nutritional enrichment of the diet. Therefore, it is not surprising that alteration of the gut microbiota is the starting point of gastrointestinal infection, obesity, type 2 diabetes, inflammatory bowel disease, colorectal cancer, and lung cancer. Diet changes and antibiotics are the major factors damaging the gut microbiota. Early exposure of the newborns to antibiotics may prevent their correct development of the immune system, exposing them to pathogen infections, allergies, and chronic inflammatory diseases. We already know much on how host genes, microbiota, and the environment interact, owing to experiments in several model animals, especially in mice; advances in molecular technology; microbiota transplantation; and comparative metagenomic analysis. However, much more remains to be known. Longitudinal studies on patients undergoing to therapy, along with the identification of bacteria prevalent in responding patients may provide valuable data for improving therapies.

Genetics of Host Protection against Helicobacter pylori Infections.

This narrative review discusses the genetics of protection against Helicobacter pylori (Hp) infection. After a brief overview of the importance of studying infectious disease genes, we provide a detailed account of the properties of Hp, with a view to those relevant for our topic. Hp displays a very high level of genetic diversity, detectable even between single colonies from the same patient. The high genetic diversity of Hp can be evaded by stratifying patients according to the infecting Hp strain. This approach enhances the power and replication of the study. Scanning for single nucleotide polymorphisms is generally not successful since genes rarely work alone. We suggest selecting genes to study from among members of the same family, which are therefore inclined to cooperate. Further, extending the analysis to the metabolism would significantly enhance the power of the study. This combined approach displays the protective role of MyD88, TIRAP, and IL1RL1 against Hp infection. Finally, several studies in humans have demonstrated that the blood T cell levels are under the genetic control of the CD39+ T regulatory cells (TREGS).

An In Vitro Model to Investigate the Role of Helicobacter pylori in Type 2 Diabetes, Obesity, Alzheimer's Disease and Cardiometabolic Disease.

Helicobacter pylori (Hp) is a Gram-negative bacterium colonizing the human stomach. Nuclear Magnetic Resonance (NMR) analysis of intracellular human gastric carcinoma cells (MKN-28) incubated with the Hp cell filtrate (Hpcf) displays high levels of amino acids, including the branched chain amino acids (BCAA) isoleucine, leucine, and valine. Polymerase chain reaction (PCR) Array Technology shows upregulation of mammalian Target Of Rapamycin Complex 1 (mTORC1), inflammation, and mitochondrial dysfunction. The review of literature indicates that these traits are common to type 2 diabetes, obesity, Alzheimer's diseases, and cardiometabolic disease. Here, we demonstrate how Hp may modulate these traits. Hp induces high levels of amino acids, which, in turn, activate mTORC1, which is the complex regulating the metabolism of the host. A high level of BCAA and upregulation of mTORC1 are, thus, directly regulated by Hp. Furthermore, Hp modulates inflammation, which is functional to the persistence of chronic infection and the asymptomatic state of the host. Finally, in order to induce autophagy and sustain bacterial colonization of gastric mucosa, the Hp toxin VacA localizes within mitochondria, causing fragmentation of these organelles, depletion of ATP, and oxidative stress. In conclusion, our in vitro disease model replicates the main traits common to the above four diseases and shows how Hp may potentially manipulate them.

Role of phage ϕ1 in two strains of Salmonella Rissen, sensitive and resistant to phage ϕ1.

BACKGROUND: The study describes the Salmonella Rissen phage ϕ1 isolated from the ϕ1-sensitive Salmonella Rissen strain RW. The same phage was then used to select the resistant strain RRϕ1+, which can harbour or not ϕ1. RESULTS: Following this approach, we found that ϕ1, upon excision from RW cells with mitomycin, behaves as a temperate phage: lyses host cells and generates phage particles; instead, upon spontaneous excision from RRϕ1+ cells, it does not generate phage particles; causes loss of phage resistance; switches the O-antigen from the smooth to the rough phenotype, and favors the transition of Salmonella Rissen from the planktonic to the biofilm growth. The RW and RRϕ1+ strains differ by 10 genes; of these, only two (phosphomannomutase_1 and phosphomannomutase_2; both involved in the mannose synthesis pathway) display significant differences at the expression levels. This result suggests that phage resistance is associated with these two genes. CONCLUSIONS: Phage ϕ1 displays the unusual property of behaving as template as well as lytic phage. This feature was used by the phage to modulate several phases of Salmonella Rissen lifestyle.

In vivo biological validation of in silico analysis: A novel approach for predicting the effects of TLR4 exon 3 polymorphisms on brucellosis.

The role of the Toll-like receptor 4 (TLR4) is of recognising intracellular and extracellular pathogens and of activating the immune response. This process can be compromised by single nucleotide polymorphisms (SNPs) which might affect the activity of several TLRs. The aim of this study is of ascertaining whether SNPs in the TLR4 of Bubalus bubalis infected by Brucella abortus, compromise the protein functionality. For this purpose, a computational analysis was performed. Next, computational predictions were confirmed by performing genotyping analysis. Finally, NMR-based metabolomics analysis was performed to identify potential biomarkers for brucellosis. The results indicate two SNPs (c. 672 A > C and c. 902 G > C) as risk factor for brucellosis in Bubalus bubalis, and three metabolites (lactate, 3-hydroxybutyrate and acetate) as biological markers for predicting the risk of developing the disease. These metabolites, together with TLR4 structural modifications in the MD2 interaction domain, are a clear signature of the immune system alteration during diverse Gram-negative bacterial infections. This suggests the possibility to extend this study to other pathogens, including Mycobacterium tuberculosis. In conclusion, this study combines multidisciplinary approaches to evaluate the biological and structural effects of SNPs on protein function.

Heterozygosity at the A625C polymorphic site of the MyD88 gene is associated with Mycobacterium bovis infection in cattle.

The study demonstrates that in cattle, animals heterozygous at the MyD88 A625C polymorphic marker have a 5-fold reduced risk for active pulmonary tuberculosis (odds ratio [OR] = 0.19; P = 6 × 10(-12)). The reduced risk, however, does not extend to animals with latent pulmonary tuberculosis (OR = 0.83; P = 0.40). Heterozygosity at the A625C single nucleotide polymorphism is associated with intermediate levels of tumor necrosis factor alpha, gamma interferon, and nitric oxide synthase (NOS). Accordingly, deficiency as well as overexpression of proinflammatory cytokines or NOS favor tuberculosis, while heterozygosity provides the animals with the optimal level of inflammation.

In vitro activity against Staphylococcus aureus of a novel antimicrobial agent, PRF-119, a recombinant chimeric bacteriophage endolysin.

Antistaphylococcal activity of the novel chimeric endolysin PRF-119 was evaluated with the microdilution method. The MIC(50) and MIC(90) of 398 methicillin-susceptible Staphylococcus aureus isolates were 0.098 µg/ml and 0.391 µg/ml, respectively (range, 0.024 to 0.780 µg/ml). Both the MIC(50) and MIC(90) values of 776 methicillin-resistant S. aureus isolates were 0.391 µg/ml (range, 0.024 to 1.563 µg/ml). All 192 clinical isolates of coagulase-negative staphylococci exhibited MIC values of >50 µg/ml. In conclusion, PRF-119 exhibited very good activity specifically against S. aureus.

Bacteriophage therapy of Salmonella enterica: a fresh appraisal of bacteriophage therapy.

BACKGROUND: The most serious criticisms leveled at bacteriophage therapy are as follows: phages induce neutralizing antibodies, phages are active only when administered shortly after bacterial infection, and phage-resistant bacteria emerge rapidly in the course of therapy. METHODS: Phages lytic for several Salmonella enterica serovars were isolated by means of standard protocols from feces of patients with gastroenteritis. Growth of S. enterica serovar Paratyphi B (Salp572(phi1S)) in the presence of phage phi1 (selected from among 8 phages for its larger host range) provided a phage phi1-resistant bacterial strain (Salp572(phi1R)). The properties of the Salp572(phi1S) and Salp572(phi1R) strains and of phage phi1 were studied in a mouse model of experimental infection. RESULTS: Phages induced nonneutralizing antibodies and were active 2 weeks after experimental infection of mice; phage-resistant bacteria were avirulent and short lived in vivo. More importantly, phage-resistant bacteria were excellent vaccines, protecting against lethal doses of heterologous S. enterica serovars. CONCLUSIONS: Phage therapy effectiveness has not yet been properly assessed.

Role of Epigenetics in Type 2 Diabetes and Obesity.

Epigenetic marks the genome by DNA methylation, histone modification or non-coding RNAs. Epigenetic marks instruct cells to respond reversibly to environmental cues and keep the specific gene expression stable throughout life. In this review, we concentrate on DNA methylation, the mechanism often associated with transgenerational persistence and for this reason frequently used in the clinic. A large study that included data from 10,000 blood samples detected 187 methylated sites associated with body mass index (BMI). The same study demonstrates that altered methylation results from obesity (OB). In another study the combined genetic and epigenetic analysis allowed us to understand the mechanism associating hepatic insulin resistance and non-alcoholic disease in Type 2 Diabetes (T2D) patients. The study underlines the therapeutic potential of epigenetic studies. We also account for seemingly contradictory results associated with epigenetics.

Bacteriophage-Resistant Salmonella rissen: An In Vitro Mitigated Inflammatory Response.

Non-typhoid Salmonella (NTS) represents one of the major causes of foodborne diseases, which are made worse by the increasing emergence of antibiotic resistance. Thus, NTS are a significant and common public health concern. The purpose of this study is to investigate whether selection for phage-resistance alters bacterial phenotype, making this approach suitable for candidate vaccine preparation. We therefore compared two strains of Salmonella enterica serovar Rissen: RR (the phage-resistant strain) and RW (the phage-sensitive strain) in order to investigate a potential cost associated with the bacterium virulence. We tested the ability of both RR and RW to infect phagocytic and non-phagocytic cell lines, the activity of virulence factors associated with the main Type-3 secretory system (T3SS), as well as the canonic inflammatory mediators. The mutant RR strain-compared to the wildtype RW strain-induced in the host a weaker innate immune response. We suggest that the mitigated inflammatory response very likely is due to structural modifications of the lipopolysaccharide (LPS). Our results indicate that phage-resistance might be exploited as a means for the development of LPS-based antibacterial vaccines.

Bacteriophages Promote Metabolic Changes in Bacteria Biofilm.

Bacterial biofilm provides bacteria with resistance and protection against conventional antimicrobial agents and the host immune system. Bacteriophages are known to move across the biofilm to make it permeable to antimicrobials. Mineral hydroxyapatite (HA) can improve the lytic activity of bacteriophages, and, together with eicosanoic acid (C20:0), can destroy the biofilm structure. Here, we demonstrate the efficacy of the combined use of phage, HA and C20:0 against Xanthomonas campestris pv campestris (Xcc) biofilm. We used nuclear magnetic resonance (NMR)-based metabolomics to investigate the molecular determinants related to the lytic action, aiming at identifying the metabolic pathways dysregulated by phage treatment. Furthermore, we identified specific markers (amino acids, lactate and galactomannan) which are involved in the control of biofilm stability. Our data show that Xccφ1, alone or in combination with HA and C20:0, interferes with the metabolic pathways involved in biofilm formation. The approach described here might be extended to other biofilm-producing bacteria.

Interaction between MyD88, TIRAP and IL1RL1 against Helicobacter pylori infection.

The Toll-interleukin 1 receptor superfamily includes the genes interleukin 1 receptor-like 1 (IL1RL1), Toll like receptors (TLRs), myeloid differentiation primary-response 88 (MyD88), and MyD88 adaptor-like (TIRAP). This study describes the interaction between MyD88, TIRAP and IL1RL1 against Helicobacter pylori infection. Cases and controls were genotyped at the polymorphic sites MyD88 rs6853, TIRAP rs8177374 and IL1RL1 rs11123923. The results show that specific combinations of IL1RL1-TIRAP (AA-CT; P: 2,8 × 10-17) and MyD88-TIRAP-IL1RL1 (AA-CT-AA; P: 1,4 × 10-8) - but not MyD88 alone-act synergistically against Helicobacter pylori. Nuclear magnetic resonance (NMR) clearly discriminates cases from controls by highlighting significantly different expression levels of several metabolites (tyrosine, tryptophan, phenylalanine, branched-chain amino acids, short chain fatty acids, glucose, sucrose, urea, etc.). NMR also identifies the following dysregulated metabolic pathways associated to Helicobacter pylori infection: phenylalanine and tyrosine metabolism, pterine biosynthesis, starch and sucrose metabolism, and galactose metabolism. Furthermore, NMR discriminates between the cases heterozygous at the IL1RL1 locus from those homozygous at the same locus. Heterozygous patients are characterized by high levels of lactate, and IL1RL1-both associated with anti-inflammatory activity-and low levels of the pro-inflammatory molecules IL-1ß, TNF-α, COX-2, and IL-6.

Author Correction: The hypothesis that Helicobacter pylori predisposes to Alzheimer's disease is biologically plausible.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

The hypothesis that Helicobacter pylori predisposes to Alzheimer's disease is biologically plausible.

There is epidemiological evidence that H. pylori might predispose to Alzheimer's disease. To understand the cellular processes potentially linking such unrelated events, we incubated the human gastric cells MNK-28 with the H. pylori peptide Hp(2-20). We then monitored the activated genes by global gene expression. The peptide modulated 77 genes, of which 65 are listed in the AlzBase database and include the hallmarks of Alzheimer's disease: APP, APOE, PSEN1, and PSEN2. A large fraction of modulated genes (30 out of 77) belong to the inflammation pathway. Remarkably, the pathways dis-regulated in Alzheimer's and Leasch-Nyhan diseases result dis-regulated also in this study. The unsuspected links between such different diseases - though still awaiting formal validation - suggest new directions for the study of neurological diseases.

Epistatic interaction between MyD88 and TIRAP against Helicobacter pylori.

The genes MyD88 and TIRAP encode the adaptor proteins MyD88 and TIRAP. TIRAP plays the crucial role of activating the MyD88-dependent pathway, which in turn controls the immune response (innate and adaptive) to Helicobacter pylori. We looked for an association of MyD88 and TIRAP with H. pylori infection. Cases and controls were genotyped at the polymorphic sites MyD88 rs6853 and TIRAP rs8177374 by real-time PCR. When the genes were analyzed separately, only TIRAP was associated with infection. When the genes were analyzed concurrently, certain combinations of MyD88 and TIRAP protected the host against H. pylori colonization more efficiently than could be done by TIRAP alone.

Rapid selection of phage-resistant mutants in Streptococcus thermophilus by immunoselection and cell sorting.

Immunoselection and flow cytometry allowed the isolation from Streptococcus thermophilus strain Str31 of double mutants displaying resistance to the phage phi31 and good acid production. Strain Str31 is very sensitive to phage phi31. This phage-host system seemed therefore particularly suitable to test the validity of the selection method adopted in this study. Mutants were stable with respect to both characters. The isolation of the double mutants required 4 to 5 days. The approach does not involve genetic manipulations and can therefore be an alternative to genetic engineering when this technology cannot be applied.

The Staphylococcus aureus peptidoglycan protects mice against the pathogen and eradicates experimentally induced infection.

Staphylococcus aureus, in spite of antibiotics, is still a major human pathogen causing a wide range of infections. The present study describes the new vaccine A170PG, a peptidoglycan-based vaccine. In a mouse model of infection, A170PG protects mice against a lethal dose of S. aureus. Protection lasts at least 40 weeks and correlates with increased survival and reduced colonization. Protection extends into drug-resistant (MRSA or VISA) and genetically diverse clinical strains. The vaccine is effective when administered - in a single dose and without adjuvant - by the intramuscular, intravenous or the aerosol routes and induces active as well as passive immunization. Of note, A170PG also displays therapeutic activity, eradicating staphylococci, even when infection is systemic. Sustained antibacterial activity and induction of a strong and rapid anti-inflammatory response are the mechanisms conferring therapeutic efficacy to A170PG.