Macrophage superclusters to the rescue.

Macrophage aggregates step in to capture blood-borne pathogens in the injured liver.

Exudate From Retail Chicken Liver Packaging Allows for Survival of Naturally Occurring Campylobacter, Coliforms, and Aerobic Microorganisms Under Drying Conditions.

Campylobacter spp. are a leading cause of human foodborne illness associated with chicken meat products in the United States. Chicken livers, including exudate from packaging, commonly carry Campylobacter and could be a source of illness if mishandled. Survivability of naturally occurring Campylobacter, total aerobic bacteria, and coliforms was determined under drying conditions in two consumer simulated environments: moist sponge and solid surface. Fresh chicken liver exudate was dispensed onto sponges and glass slides and allowed to dry under ambient conditions for 7 days. Bacterial concentration was measured at 0, 6, 24, 48, 72, and 168 h. Total aerobic population did not decrease by more than one log over 7 days and did not correlate to water activity or time in either simulation. Coliform concentrations increased in sponge simulations but decreased in solid surface simulations. Further, coliform concentrations were significantly higher in sponge simulations than in solid surface. Campylobacter was naturally present in exudate and survived at least to 6 h in every trial. Campylobacter was recoverable at 24 h in some sponge trials. However, Campylobacter concentration was strongly correlated to water activity. Fresh chicken liver exudate could present a risk of campylobacteriosis to consumers if mishandled even after drying.

Bacillus subtilis pretreatment alleviates ethanol-induced acute liver injury by regulating the Gut-liver axis in mice.

This study was designed to investigate the hepatoprotective effects of Bacillus subtilis, a commensal bacterial species in the human gut, on ethanol-induced acute liver damage and the underlying mechanisms in mice. Male ICR mice challenged with three doses of ethanol (5.5 g/kg BW) exhibited a significant increase in serum aminotransferase activities and TNF-α level, liver fat accumulation, and activation of NF-κB signaling and NLRP3 inflammasome, which was suppressed by pretreatment with Bacillus subtilis. Besides, Bacillus subtilis inhibited acute ethanol-induced intestinal villi shortening and epithelial loss, the decline of protein levels of intestinal tight junction protein ZO-1 and occludin, and elevation of serum LPS level. Furthermore, the upregulation of mucin-2 (MUC2) and the downregulation of anti-microbial Reg3B and Reg3G levels induced by ethanol were repressed by Bacillus subtilis. Lastly, Bacillus subtilis pretreatment significantly increased the abundance of the intestinal Bacillus, but had no effects on the binge drinking-induced increase of Prevotellaceae abundance. These results demonstrate that Bacillus subtilis supplementation could ameliorate binge drinking-induced liver injury, and thus may serve as a functional dietary supplement for binge drinkers.

Microbiome Alterations in Alcohol Use Disorder and Alcoholic Liver Disease.

Microbiome alterations are emerging as one of the most important factors that influence the course of alcohol use disorder (AUD). Recent advances in bioinformatics enable more robust and accurate characterization of changes in the composition of the microbiome. In this study, our objective was to provide the most comprehensive and up-to-date evaluation of microbiome alterations associated with AUD and alcoholic liver disease (ALD). To achieve it, we have applied consistent, state of art bioinformatic workflow to raw reads from multiple 16S rRNA sequencing datasets. The study population consisted of 122 patients with AUD, 75 with ALD, 54 with non-alcoholic liver diseases, and 260 healthy controls. We have found several microbiome alterations that were consistent across multiple datasets. The most consistent changes included a significantly lower abundance of multiple butyrate-producing families, including Ruminococcaceae, Lachnospiraceae, and Oscillospiraceae in AUD compared to HC and further reduction of these families in ALD compared with AUD. Other important results include an increase in endotoxin-producing Proteobacteria in AUD, with the ALD group having the largest increase. All of these alterations can potentially contribute to increased intestinal permeability and inflammation associated with AUD and ALD.

Characteristics of the intestinal bacterial microbiota profiles in Bifidobacterium pseudocatenulatum LI09 pre-treated rats with D-galactosamine-induced liver injury.

Bifidobacterium pseudocatenulatum LI09 could prevent D-galactosamine-induced liver injury. Our previous study has preliminarily determined that different intestinal microbiota profiles existed in the LI09-treated rats. Due to the sample size limitation, some subsequent analyses could not be achieved. In the current study, we conducted different experiments and bioinformatic analyses to characterise the distinct intestinal bacterial microbiota profiles in the LI09-treated rats with liver injury (i.e., LI09 group). Partition around medoids clustering analysis determined two intestinal microbiota profiles (i.e., Cluster_1_LI09 and Cluster_2_LI09) in LI09 group. Compared with Cluster_2_LI09, Cluster_1_LI09 group was determined at less dysbiotic microbial status and with lower level of liver injury. The two microbiota profiles were determined with distinct representative amplicon sequence variants (ASVs), among which, ASV1_Akkermansia and ASV3_Bacteroides were most associated with Cluster_1_LI09 and Cluster_2_LI09, respectively. Multiple representative phylotypes in Cluster_1_LI09 negatively correlating with liver function variables were assigned to Parabacteroides, suggesting Parabacteroides could benefit LI09 on modulating the liver function. In addition, ASV310_Lachnospiraceae, ASV501_Muribaculaceae and ASV484_Lachnospiraceae were determined as network gatekeepers in Cluster_1_LI09 network. The relevant results suggest that some intestinal bacteria could assist LI09 in lowering the intestinal microbial dysbiosis in the rats with liver injury, and their clinical application deserves further investigation.

Cluster of Donor-Derived Cryptococcosis after Liver and Kidney Transplantation.

Cryptococcosis infection after transplantation is easily overlooked or misdiagnosed. We report a cluster of donor-derived cryptococcosis infection in liver and kidney transplant recipients from the same donor in China. Infections occurred within 1 month after transplantation, and were confirmed by using biopsies and blood tests.

Complex genetics cause and constrain fungal persistence in different parts of the mammalian body.

Determining how genetic polymorphisms enable certain fungi to persist in mammalian hosts can improve understanding of opportunistic fungal pathogenesis, a source of substantial human morbidity and mortality. We examined the genetic basis of fungal persistence in mice using a cross between a clinical isolate and the lab reference strain of the budding yeast Saccharomyces cerevisiae. Employing chromosomally encoded DNA barcodes, we tracked the relative abundances of 822 genotyped, haploid segregants in multiple organs over time and performed linkage mapping of their persistence in hosts. Detected loci showed a mix of general and antagonistically pleiotropic effects across organs. General loci showed similar effects across all organs, while antagonistically pleiotropic loci showed contrasting effects in the brain vs the kidneys, liver, and spleen. Persistence in an organ required both generally beneficial alleles and organ-appropriate pleiotropic alleles. This genetic architecture resulted in many segregants persisting in the brain or in nonbrain organs, but few segregants persisting in all organs. These results show complex combinations of genetic polymorphisms collectively cause and constrain fungal persistence in different parts of the mammalian body.

Within-host evolution of a gut pathobiont facilitates liver translocation.

Gut commensal bacteria with the ability to translocate across the intestinal barrier can drive the development of diverse immune-mediated diseases1-4. However, the key factors that dictate bacterial translocation remain unclear. Recent studies have revealed that gut microbiota strains can adapt and evolve throughout the lifetime of the host5-9, raising the possibility that changes in individual commensal bacteria themselves over time may affect their propensity to elicit inflammatory disease. Here we show that within-host evolution of the model gut pathobiont Enterococcus gallinarum facilitates bacterial translocation and initiation of inflammation. Using a combination of in vivo experimental evolution and comparative genomics, we found that E. gallinarum diverges into independent lineages adapted to colonize either luminal or mucosal niches in the gut. Compared with ancestral and luminal E. gallinarum, mucosally adapted strains evade detection and clearance by the immune system, exhibit increased translocation to and survival within the mesenteric lymph nodes and liver, and induce increased intestinal and hepatic inflammation. Mechanistically, these changes in bacterial behaviour are associated with non-synonymous mutations or insertion-deletions in defined regulatory genes in E. gallinarum, altered microbial gene expression programs and remodelled cell wall structures. Lactobacillus reuteri also exhibited broadly similar patterns of divergent evolution and enhanced immune evasion in a monocolonization-based model of within-host evolution. Overall, these studies define within-host evolution as a critical regulator of commensal pathogenicity that provides a unique source of stochasticity in the development and progression of microbiota-driven disease.

Lactobacillus reuteri joins the liver autoimmune arena.

Type 1 CD8 T cells (Tc1s) have been implicated in liver injury in autoimmune hepatitis (AIH) through mechanisms that have so far been unclear. In this issue of Cell Host & Microbe, Pandey et al. show that the aryl hydrocarbon receptor ligand-producing pathobiont Lactobacillus reuteri induces Tc1-mediated AIH-like pathology in mice with Tet-methylcytosine-dioxygenase-2 deficiency.

Tet2 deficiency drives liver microbiome dysbiosis triggering Tc1 cell autoimmune hepatitis.

The triggers that drive interferon-γ (IFNγ)-producing CD8 T cell (Tc1 cell)-mediated autoimmune hepatitis (AIH) remain obscure. Here, we show that lack of hematopoietic Tet methylcytosine dioxygenase 2 (Tet2), an epigenetic regulator associated with autoimmunity, results in the development of microbiota-dependent AIH-like pathology, accompanied by hepatic enrichment of aryl hydrocarbon receptor (AhR) ligand-producing pathobionts and rampant Tc1 cell immunity. We report that AIH-like disease development is dependent on both IFNγ and AhR signaling, as blocking either reverts ongoing AIH-like pathology. Illustrating the critical role of AhR-ligand-producing pathobionts in this condition, hepatic translocation of the AhR ligand indole-3-aldehyde (I3A)-releasing Lactobacillus reuteri is sufficient to trigger AIH-like pathology. Finally, we demonstrate that I3A is required for L. reuteri-induced Tc1 cell differentiation in vitro and AIH-like pathology in vivo, both of which are restrained by Tet2 within CD8 T cells. This AIH-disease model may contribute to the development of therapeutics to alleviate AIH.

[LAMTOR2 deficiency exacerbates Klebsiella pneumoniae-induced liver sepsis in mice].

Objective To explore the biological function and mechanisms of LAMTOR2 during Klebsiella pneumoniae(K. pneumoniae) induced liver sepsis by establishing late endosomal/lysosomal adaptor 2(LAMTOR2) gene liver conditional knockout mouse model infected by K. pneumoniae. Methods LAMTOR2 gene liver conditional knockout mice (LAMTOR2flox/flox; Alb-Cre+) and littermate controls (LAMTOR2flox/flox) were generated and bred. LAMTOR2 gene knockout efficiency in liver was determined by real-time quantitative PCR (RT-qPCR) and Western blot analysis. Then, both group mice were infected with K. pneumoniae, and survival rates and liver pathological changes were determined. The expression levels of liver TNF-α, IL-1ß and CXCL1 mRNA were detected by RT-qPCR. Results LAMTOR2 gene liver conditional knockout mice were generated and bred successfully; compared to the littermate controls, LAMTOR2flox/flox, Alb-Cre+ mice showed lower survival rates and more severe liver injury. The expression levels of TNF-α, IL-1ß and CXCL1 mRNA were reduced in LAMTOR2flox/flox and the ability of immune response was decreased in mice. Alb-Cre+ mice liver compared to these of littermate controls post K. pneumoniae infections. Conclusion LAMTOR2 plays a protective role during K. pneumoniae-induced liver sepsis.

A lethal model of Leptospira infection in hamster nasal mucosa.

Leptospirosis is a fatal zoonosis caused by contact between skin or a mucosal surface and contaminated soil or water. Hamsters were infected by intraperitoneal injection fto establish experimental leptospirosis, which is not a natural route of infection. There are no reports of nasal mucosal infection in hamsters. In this study, infection of the nasal mucosa was performed to establish a model of natural infection. Both methods of infection can cause lethal models with similar symptoms in the later stages of infection, such as weight loss, blood concentration, increased neutrophils (GRAN), and decreased lymphocytes (LYM) in the blood, severe organ damage and liver function obstruction. The burden of Leptospira in the organs and blood was lower in the mucosal inoculation groups at 1 day after infection. However, mucosal infection induced a higher Leptospira burden in urine than intraperitoneal infection in the late stages of infection. After nasal mucosal infection, antibody levels were higher and lasted longer. These results indicated that the route of nasal mucosal infection is a good choice for studying leptospirosis in hamsters.

Effect of Morus alba leaf extract dose on lipid oxidation, microbiological stability, and sensory evaluation of functional liver pâtés during refrigerated storage.

Mulberry (Morus alba L.), and above all the extract from the leaves of this plant, is a natural medicine that has been used in traditional medicine for hundreds of years. Mulberry leaves contains polyphenol compounds: flavonoids, coumarins, numerous phenolic acids, as well as terpenes and steroids. The antioxidant effect of these compounds may be beneficial to the fat fraction of meat products, thereby increasing their functional qualities. The aim of the study was to evaluate the effectiveness of the use of mulberry water leaf extract, as an additive limiting adverse fat changes and affecting the functionality in model liver pâtés. Pork pâtés were prepared by replacing 20% of animal fat with rapeseed oil (RO), and water extract of mulberry leaves was added in the proportion of 0.2%, 0.6% and 1.0%. It has been shown that the addition of mulberry leaf extract delayed the appearance of primary and secondary fat oxidation products. The most effective antioxidant effect during 15-day storage was observed in the sample with the addition of 0.6% and 1.0% water mulberry leaf extract. These samples also showed inhibiting activity against angiotensin-converting enzymes and cholinesterase's. During storage, the tested pâtés had a high sensory quality with unchanged microbiological quality. Mulberry leaf extract can be an interesting addition to the production of fat meat products, delaying adverse changes in the lipid fraction and increasing the functionality of products.

CRIg on liver macrophages clears pathobionts and protects against alcoholic liver disease.

Complement receptor of immunoglobulin superfamily (CRIg) is expressed on liver macrophages and directly binds complement component C3b or Gram-positive bacteria to mediate phagocytosis. CRIg plays important roles in several immune-mediated diseases, but it is not clear how its pathogen recognition and phagocytic functions maintain homeostasis and prevent disease. We previously associated cytolysin-positive Enterococcus faecalis with severity of alcohol-related liver disease. Here, we demonstrate that CRIg is reduced in liver tissues from patients with alcohol-related liver disease. CRIg-deficient mice developed more severe ethanol-induced liver disease than wild-type mice; disease severity was reduced with loss of toll-like receptor 2. CRIg-deficient mice were less efficient than wild-type mice at clearing Gram-positive bacteria such as Enterococcus faecalis that had translocated from gut to liver. Administration of the soluble extracellular domain CRIg-Ig protein protected mice from ethanol-induced steatohepatitis. Our findings indicate that ethanol impairs hepatic clearance of translocated pathobionts, via decreased hepatic CRIg, which facilitates progression of liver disease.

NLRP3 Inflammasome Contributes to Host Defense Against Talaromyces marneffei Infection.

Talaromyce marneffei is an important thermally dimorphic pathogen causing disseminated mycoses in immunocompromised individuals in southeast Asia. Previous studies have suggested that NLRP3 inflammasome plays a critical role in antifungal immunity. However, the mechanism underlying the role of NLRP3 inflammasome activation in host defense against T. marneffei remains unclear. We show that T. marneffei yeasts but not conidia induce potent IL-1ß production. The IL-1ß response to T. marneffei yeasts is differently regulated in different cell types; T. marneffei yeasts alone are able to induce IL-1ß production in human PBMCs and monocytes, whereas LPS priming is essential for IL-1ß response to yeasts. We also find that Dectin-1/Syk signaling pathway mediates pro-IL-1ß production, and NLRP3-ASC-caspase-1 inflammasome is assembled to trigger the processing of pro-IL-1ß into IL-1ß. In vivo, mice deficient in NLRP3 or caspase-1 exhibit higher mortality rate and fungal load compared to wild-type mice after systemic T. marneffei infection, which correlates with the diminished recruitment of CD4 T cells into granulomas in knockout mice. Thus, our study first demonstrates that NLRP3 inflammasome contributes to host defense against T. marneffei infection.

Gastrodin attenuates perfluorooctanoic acid-induced liver injury by regulating gut microbiota composition in mice.

Perfluorooctanoic acid (PFOA) can accumulate in the livers of humans and animals via the food chain, resulting into liver injury, which is closely related to intestinal flora dysbiosis. Gastrodin has been reported to have hepatoprotective effect. However, whether gastrodin can alleviate PFOA-induced liver injury via modulating gut microbiota remains unclear. Herein, a PFOA-induced liver injury model was established by gavage of PFOA (5 mg/kg body weight) in 2% Tween 80 solution once daily for 6 weeks in mice, and then gastrodin in saline (20 mg/kg body weight) was used once daily for 8 weeks to treat liver damage. The biochemical indexes associated with liver function, oxidative stress, and inflammatory factors were examined. Hematoxylin-eosin staining was used to determine the liver histopathological changes. Besides, 16S rRNA sequencing was used to analyze the difference of gut microbiota between the model and treatment groups. The results showed that gastrodin significantly improved the oxidative stress caused by PFOA. Intestinal flora analysis showed that gastrodin treatment significantly increased the relative abundance of probiotics, such as Lactobacillus, Bifidobacterium, and Bacteroides, while the harmful bacteria, including Desulfovibrio were decreased. Gastrodin treatment also significantly increased the level of short-chain fatty acids (SCFAs), such as butyric acid and isobutyric acid. Spearman correlation analysis showed that the composition changes of gut microbiota and SCFAs increase were both beneficial to alleviate the liver injury caused by PFOA. To sum up, gastrodin can effectively alleviate PFOA-induced liver injury through regulating gut microbiota composition.

Polydextrose with and without Bifidobacterium animalis ssp. lactis 420 drives the prevalence of Akkermansia and improves liver health in a multi-compartmental obesogenic mice study.

The past two decades of research have raised gut microbiota composition as a contributing factor to the development of obesity, and higher abundance of certain bacterial species has been linked to the lean phenotype, such as Akkermansia muciniphila. The ability of pre- and probiotics to affect metabolic health could be via microbial community alterations and subsequently changes in metabolite profiles, modulating for example host energy balance via complex signaling pathways. The aim of this mice study was to determine how administration of a prebiotic fiber, polydextrose (PDX) and a probiotic Bifidobacterium animalis ssp. lactis 420 (B420), during high fat diet (HFD; 60 kcal% fat) affects microbiota composition in the gastrointestinal tract and adipose tissue, and metabolite levels in gut and liver. In this study C57Bl/6J mice (N = 200) were split in five treatments and daily gavaged: 1) Normal control (NC); 2) HFD; 3) HFD + PDX; 4) HFD + B420 or 5) HFD + PDX + B420 (HFD+S). At six weeks of treatment intraperitoneal glucose-tolerance test (IPGTT) was performed, and feces were collected at weeks 0, 3, 6 and 9. At end of the intervention, ileum and colon mucosa, adipose tissue and liver samples were collected. The microbiota composition in fecal, ileum, colon and adipose tissue was analyzed using 16S rDNA sequencing, fecal and liver metabolomics were performed by nuclear magnetic resonance (NMR) spectroscopy. It was found that HFD+PDX intervention reduced body weight gain and hepatic fat compared to HFD. Sequencing the mice adipose tissue (MAT) identified Akkermansia and its prevalence was increased in HFD+S group. Furthermore, by the inclusion of PDX, fecal, lleum and colon levels of Akkermansia were increased and liver health was improved as the detoxification capacity and levels of methyl-donors were increased. These new results demonstrate how PDX and B420 can affect the interactions between gut, liver and adipose tissue.

Expeditious recruitment of circulating memory CD8 T cells to the liver facilitates control of malaria.

Circulating memory CD8 T cell trafficking and protective capacity during liver-stage malaria infection remains undefined. We find that effector memory CD8 T cells (Tem) infiltrate the liver within 6 hours after malarial or bacterial infections and mediate pathogen clearance. Tem recruitment coincides with rapid transcriptional upregulation of inflammatory genes in Plasmodium-infected livers. Recruitment requires CD8 T cell-intrinsic LFA-1 expression and the presence of liver phagocytes. Rapid Tem liver infiltration is distinct from recruitment to other non-lymphoid tissues in that it occurs both in the absence of liver tissue resident memory "sensing-and-alarm" function and ∼42 hours earlier than in lung infection by influenza virus. These data demonstrate relevance for Tem in protection against malaria and provide generalizable mechanistic insights germane to control of liver infections.

A large panel of chicken cells are invaded in vivo by Salmonella Typhimurium even when depleted of all known invasion factors.

Poultry are the main source of human infection by Salmonella. As infected poultry are asymptomatic, identifying infected poultry farms is difficult, thus controlling animal infections is of primary importance. As cell tropism is known to govern disease, our aim was therefore to identify infected host-cell types in the organs of chicks known to be involved in Salmonella infection and investigate the role of the three known invasion factors in this process (T3SS-1, Rck and PagN). Chicks were inoculated with wild-type or isogenic fluorescent Salmonella Typhimurium mutants via the intracoelomic route. Our results show that liver, spleen, gall bladder and aortic vessels could be foci of infection, and that phagocytic and non-phagocytic cells, including immune, epithelial and endothelial cells, are invaded in vivo in each organ. Moreover, a mutant defective for the T3SS-1, Rck and PagN remained able to colonize organs like the wild-type strain and invaded non-phagocytic cells in each organ studied. As the infection of the gall bladder had not previously been described in chicks, invasion of gall bladder cells was confirmed by immunohistochemistry and infection was shown to last several weeks after inoculation. Altogether, for the first time these findings provide insights into cell tropism of Salmonella in relevant organs involved in Salmonella infection in chicks and also demonstrate that the known invasion factors are not required for entry into these cell types.