Microbial composition associated with biliary stents in patients undergoing pancreatic resection for cancer.

Malignant bile duct obstruction is typically treated by biliary stenting, which however increases the risk of bacterial infections. Here, we analyzed the microbial content of the biliary stents from 56 patients finding widespread microbial colonization. Seventeen of 36 prevalent stent species are common oral microbiome members, associate with disease conditions when present in the gut, and include dozens of biofilm- and antimicrobial resistance-related genes. This work provides an overview of the microbial communities populating the stents.

Longitudinal gut microbiome changes in immune checkpoint blockade-treated advanced melanoma.

Multiple clinical trials targeting the gut microbiome are being conducted to optimize treatment outcomes for immune checkpoint blockade (ICB). To improve the success of these interventions, understanding gut microbiome changes during ICB is urgently needed. Here through longitudinal microbiome profiling of 175 patients treated with ICB for advanced melanoma, we show that several microbial species-level genome bins (SGBs) and pathways exhibit distinct patterns from baseline in patients achieving progression-free survival (PFS) of 12 months or longer (PFS ≥12) versus patients with PFS shorter than 12 months (PFS <12). Out of 99 SGBs that could discriminate between these two groups, 20 were differentially abundant only at baseline, while 42 were differentially abundant only after treatment initiation. We identify five and four SGBs that had consistently higher abundances in patients with PFS ≥12 and <12 months, respectively. Constructing a log ratio of these SGBs, we find an association with overall survival. Finally, we find different microbial dynamics in different clinical contexts including the type of ICB regimen, development of immune-related adverse events and concomitant medication use. Insights into the longitudinal dynamics of the gut microbiome in association with host factors and treatment regimens will be critical for guiding rational microbiome-targeted therapies aimed at enhancing ICB efficacy.

High dietary inflammatory index associates with inflammatory proteins in plasma.

BACKGROUND AND AIM: Unhealthy dietary habits and highly caloric foods induce metabolic alterations and promote the development of the inflammatory consequences of obesity, insulin resistance, diabetes and cardiovascular diseases. Describing an inflammatory effect of diet is difficult to pursue, owing lacks of standardized quali-quantitative dietary assessments. The Dietary Inflammatory Index (DII) has been proposed as an estimator of the pro- or anti-inflammatory effect of nutrients and higher DII values, which indicate an increased intake of nutrients with pro-inflammatory effects, relate to an increased risk of metabolic and cardiovascular diseases and we here assessed whether they reflect biologically relevant plasmatic variations of inflammatory proteins. METHODS: In this cross-sectional study, seven days dietary records from 663 subjects in primary prevention for cardiovascular diseases were analyzed to derive the intake of nutrients, foods and to calculate DII. To associate DII with the Normalized Protein eXpression (NPX), an index of abundance, of a targeted panel of 368 inflammatory biomarkers (Olink™) measured in the plasma, we divided the population by the median value of DII (1.60 (0.83-2.30)). RESULTS: 332 subjects with estimated DII over the median value reported a higher intake of saturated fats but lower intakes of poly-unsaturated fats, including omega-3 and omega-6 fats, versus subjects with estimated dietary DII below the median value (N = 331). The NPX of 61 proteins was increased in the plasma of subjects with DII > median vs. subjects with DII < median. By contrast, in the latter group, we underscored only 3 proteins with increased NPX. Only 23, out of these 64 proteins, accurately identified subjects with DII > median (Area Under the Curve = 0.601 (0.519-0.668), p = 0.035). CONCLUSION: This large-scale proteomic study supports that higher DII reflects changes in the plasmatic abundance of inflammatory proteins. Larger studies are warranted to validate.

Draft genome sequence of a representative strain of the Catenibacterium genus isolated from human feces.

A strain from a previously undescribed species belonging to the Catenibacterium genus was isolated from the stool of a healthy volunteer. The strain is strictly anaerobic, and the genome encodes a CRISPR-Cas system and genes related to trimethylamine production.

Gut and oral microbiome modulate molecular and clinical markers of schizophrenia-related symptoms: A transdiagnostic, multilevel pilot study.

Although increasing evidence links microbial dysbiosis with the risk for psychiatric symptoms through the microbiome-gut-brain axis (MGBA), the specific mechanisms remain poorly characterized. In a diagnostically heterogeneous group of treated psychiatric cases and nonpsychiatric controls, we characterized the gut and oral microbiome, plasma cytokines, and hippocampal inflammatory processes via proton magnetic resonance spectroscopic imaging (1H-MRSI). Using a transdiagnostic approach, these data were examined in association with schizophrenia-related symptoms measured by the Positive and Negative Syndrome Scale (PANSS). Psychiatric cases had significantly greater heterogeneity of gut alpha diversity and an enrichment of pathogenic taxa, like Veillonella and Prevotella, in the oral microbiome, which was an accurate classifier of phenotype. Cases exhibited significantly greater positive, negative, and general PANSS scores that uniquely correlated with bacterial taxa. Strong, positive correlations of bacterial taxa were also found with cytokines and hippocampal gliosis, dysmyelination, and excitatory neurotransmission. This pilot study supports the hypothesis that the MGBA influences psychiatric symptomatology in a transdiagnostic manner. The relative importance of the oral microbiome in peripheral and hippocampal inflammatory pathways was highlighted, suggesting opportunities for probiotics and oral health to diagnose and treat psychiatric conditions.

Cross-cohort gut microbiome associations with immune checkpoint inhibitor response in advanced melanoma.

The composition of the gut microbiome has been associated with clinical responses to immune checkpoint inhibitor (ICI) treatment, but there is limited consensus on the specific microbiome characteristics linked to the clinical benefits of ICIs. We performed shotgun metagenomic sequencing of stool samples collected before ICI initiation from five observational cohorts recruiting ICI-naive patients with advanced cutaneous melanoma (n = 165). Integrating the dataset with 147 metagenomic samples from previously published studies, we found that the gut microbiome has a relevant, but cohort-dependent, association with the response to ICIs. A machine learning analysis confirmed the link between the microbiome and overall response rates (ORRs) and progression-free survival (PFS) with ICIs but also revealed limited reproducibility of microbiome-based signatures across cohorts. Accordingly, a panel of species, including Bifidobacterium pseudocatenulatum, Roseburia spp. and Akkermansia muciniphila, associated with responders was identified, but no single species could be regarded as a fully consistent biomarker across studies. Overall, the role of the human gut microbiome in ICI response appears more complex than previously thought, extending beyond differing microbial species simply present or absent in responders and nonresponders. Future studies should adopt larger sample sizes and take into account the complex interplay of clinical factors with the gut microbiome over the treatment course.

Traditional Farming Lifestyle in Old Older Mennonites Modulates Human Milk Composition.

Background: In addition to farming exposures in childhood, maternal farming exposures provide strong protection against allergic disease in their children; however, the effect of farming lifestyle on human milk (HM) composition is unknown. Objective: This study aims to characterize the maternal immune effects of Old Order Mennonite (OOM) traditional farming lifestyle when compared with Rochester (ROC) families at higher risk for asthma and allergic diseases using HM as a proxy. Methods: HM samples collected at median 2 months of lactation from 52 OOM and 29 ROC mothers were assayed for IgA1 and IgA2 antibodies, cytokines, endotoxin, HM oligosaccharides (HMOs), and targeted fatty acid (FA) metabolites. Development of early childhood atopic diseases in children by 3 years of age was assessed. In addition to group comparisons, systems level network analysis was performed to identify communities of multiple HM factors in ROC and OOM lifestyle. Results: HM contains IgA1 and IgA2 antibodies broadly recognizing food, inhalant, and bacterial antigens. OOM HM has significantly higher levels of IgA to peanut, ovalbumin, dust mites, and Streptococcus equii as well TGF-ß2, and IFN-λ3. A strong correlation occurred between maternal antibiotic use and levels of several HMOs. Path-based analysis of HMOs shows lower activity in the path involving lactoneohexaose (LNH) in the OOM as well as higher levels of lacto-N-neotetraose (LNnT) and two long-chain FAs C-18OH (stearic acid) and C-23OH (tricosanoic acid) compared with Rochester HM. OOM and Rochester milk formed five different clusters, e.g., butyrate production was associated with Prevotellaceae, Veillonellaceae, and Micrococcaceae cluster. Development of atopic disease in early childhood was more common in Rochester and associated with lower levels of total IgA, IgA2 to dust mite, as well as of TSLP. Conclusion: Traditional, agrarian lifestyle, and antibiotic use are strong regulators of maternally derived immune and metabolic factors, which may have downstream implications for postnatal developmental programming of infant's gut microbiome and immune system.

Infant gut microbiome is enriched with Bifidobacterium longum ssp. infantis in Old Order Mennonites with traditional farming lifestyle.

BACKGROUND: Growing up on traditional, single-family farms is associated with protection against asthma in school age, but the mechanisms against early manifestations of atopic disease are largely unknown. We sought determine the gut microbiome and metabolome composition in rural Old Order Mennonite (OOM) infants at low risk and Rochester, NY urban/suburban infants at high risk for atopic diseases. METHODS: In a cohort of 65 OOM and 39 Rochester mother-infant pairs, 101 infant stool and 61 human milk samples were assessed by 16S rRNA gene sequencing for microbiome composition and qPCR to quantify Bifidobacterium spp. and B. longum ssp. infantis (B. infantis), a consumer of human milk oligosaccharides (HMOs). Fatty acids (FAs) were analyzed in 34 stool and human 24 milk samples. Diagnoses and symptoms of atopic diseases by 3 years of age were assessed by telephone. RESULTS: At a median age of 2 months, stool was enriched with Bifidobacteriaceae, Clostridiaceae, and Aerococcaceae in the OOM compared with Rochester infants. B. infantis was more abundant (p < .001) and prevalent, detected in 70% of OOM compared with 21% of Rochester infants (p < .001). Stool colonized with B. infantis had higher levels of lactate and several medium- to long/odd-chain FAs. In contrast, paired human milk was enriched with a distinct set of FAs including butyrate. Atopic diseases were reported in 6.5% of OOM and 35% of Rochester children (p < .001). CONCLUSION: A high rate of B. infantis colonization, similar to that seen in developing countries, is found in the OOM at low risk for atopic diseases.

Insights into the genome structure of four acetogenic bacteria with specific reference to the Wood-Ljungdahl pathway.

Acetogenic bacteria are obligate anaerobes with the ability of converting carbon dioxide and other one-carbon substrates into acetate through the Wood-Ljungdahl (WL) pathway. These substrates are becoming increasingly important feedstock in industrial microbiology. The main potential industrial application of acetogenic bacteria is the production of metabolites that constitute renewable energy sources (biofuel); such bacteria are of particular interest for this purpose thanks to their low energy requirements for large-scale cultivation. Here, we report new genome sequences for four species, three of them are reported for the first time, namely Acetobacterium paludosum DSM 8237, Acetobacterium tundrae DSM 917, Acetobacterium bakii DSM 8239, and Alkalibaculum bacchi DSM 221123. We performed a comparative genomic analysis focused on the WL pathway's genes and their encoded proteins, using Acetobacterium woodii as a reference genome. The Average Nucleotide Identity (ANI) values ranged from 70% to 95% over an alignment length of 5.4-6.5 Mbp. The core genome consisted of 363 genes, whereas the number of unique genes in a single genome ranged from 486 in A. tundrae to 2360 in A.bacchi. No significant rearrangements were detected in the gene order for the Wood-Ljungdahl pathway however, two species showed variations in genes involved in formate metabolism: A. paludosum harbor two copies of fhs1, and A. bakii a truncated fdhF1. The analysis of protein networks highlighted the expansion of protein orthologues in A. woodii compared to A. bacchi, whereas protein networks involved in the WL pathway were more conserved. This study has increased our understanding on the evolution of the WL pathway in acetogenic bacteria.

Two-Way Chemical Communication between Artificial and Natural Cells.

Artificial cells capable of both sensing and sending chemical messages to bacteria have yet to be built. Here we show that artificial cells that are able to sense and synthesize quorum signaling molecules can chemically communicate with V. fischeri, V. harveyi, E. coli, and P. aeruginosa. Activity was assessed by fluorescence, luminescence, RT-qPCR, and RNA-seq. Two potential applications for this technology were demonstrated. First, the extent to which artificial cells could imitate natural cells was quantified by a type of cellular Turing test. Artificial cells capable of sensing and in response synthesizing and releasing N-3-(oxohexanoyl)homoserine lactone showed a high degree of likeness to natural V. fischeri under specific test conditions. Second, artificial cells that sensed V. fischeri and in response degraded a quorum signaling molecule of P. aeruginosa (N-(3-oxododecanoyl)homoserine lactone) were constructed, laying the foundation for future technologies that control complex networks of natural cells.

The microbiome in early life: implications for health outcomes.

Recent studies have characterized how host genetics, prenatal environment and delivery mode can shape the newborn microbiome at birth. Following this, postnatal factors, such as antibiotic treatment, diet or environmental exposure, further modulate the development of the infant's microbiome and immune system, and exposure to a variety of microbial organisms during early life has long been hypothesized to exert a protective effect in the newborn. Furthermore, epidemiological studies have shown that factors that alter bacterial communities in infants during childhood increase the risk for several diseases, highlighting the importance of understanding early-life microbiome composition. In this review, we describe how prenatal and postnatal factors shape the development of both the microbiome and the immune system. We also discuss the prospects of microbiome-mediated therapeutics and the need for more effective approaches that can reconfigure bacterial communities from pathogenic to homeostatic configurations.

Microbiota-driven transcriptional changes in prefrontal cortex override genetic differences in social behavior.

Gene-environment interactions impact the development of neuropsychiatric disorders, but the relative contributions are unclear. Here, we identify gut microbiota as sufficient to induce depressive-like behaviors in genetically distinct mouse strains. Daily gavage of vehicle (dH2O) in nonobese diabetic (NOD) mice induced a social avoidance behavior that was not observed in C57BL/6 mice. This was not observed in NOD animals with depleted microbiota via oral administration of antibiotics. Transfer of intestinal microbiota, including members of the Clostridiales, Lachnospiraceae and Ruminococcaceae, from vehicle-gavaged NOD donors to microbiota-depleted C57BL/6 recipients was sufficient to induce social avoidance and change gene expression and myelination in the prefrontal cortex. Metabolomic analysis identified increased cresol levels in these mice, and exposure of cultured oligodendrocytes to this metabolite prevented myelin gene expression and differentiation. Our results thus demonstrate that the gut microbiota modifies the synthesis of key metabolites affecting gene expression in the prefrontal cortex, thereby modulating social behavior.

Supercritical CO2 induces marked changes in membrane phospholipids composition in Escherichia coli K12.

Supercritical carbon dioxide (SC-CO2) treatment is one of the most promising alternative techniques for pasteurization of both liquid and solid food products. The inhibitory effect of SC-CO2 on bacterial growth has been investigated in different species, but the precise mechanism of action remains unknown. Membrane permeabilization has been proposed to be the first event in SC-CO2-mediated inactivation. Flow cytometry, high performance liquid chromatography­electrospray ionization­mass spectrometry and NMR analyses were performed to investigate the effect of SC-CO2 treatment on membrane lipid profile and membrane permeability in Escherichia coli K12. After 15 min of SC-CO2 treatment at 120 bar and 35 °C, the majority of bacterial cells dissipated their membrane potential (95 %) and lost membrane integrity, as 81 % become partially permeabilized and 18 % fully permeabilized. Membrane permeabilization was associated with a 20 % decrease in bacterial biovolume and to a strong (>50 %) reduction in phosphatidylglycerol (PG) membrane lipids, without altering the fatty acid composition and the degree of unsaturation of acyl chains. PGs are thought to play an important role in membrane stability, by reducing motion of phosphatidylethanolamine (PE) along the membrane bilayer, therefore promoting the formation of inter-lipid hydrogen bonds. In addition, the decrease in intracellular pH induced by SC-CO2 likely alters the chemical properties of phospholipids and the PE/PG ratio. Biophysical effects of SC-CO2 thus cause a strong perturbation of membrane architecture in E. coli, and such alterations are likely associated with its strong inactivation effect.

Comparison of quantitative PCR and flow cytometry as cellular viability methods to study bacterial membrane permeabilization following supercritical CO2 treatment.

Foodborne illness due to bacterial pathogens is increasing worldwide as a consequence of the higher consumption of fresh and minimally processed food products, which are more easily cross-contaminated. The efficiency of food pasteurization methods is usually measured by c.f.u. plate counts, a method discriminating viable from dead cells on the basis of the ability of cells to replicate and form colonies on standard growth media, thus ignoring viable but not cultivable cells. Supercritical CO2 (SC-CO2) has recently emerged as one of the most promising fresh food pasteurization techniques, as an alternative to traditional, heat-based methods. In the present work, using three SC-CO2-treated foodborne bacteria (Listeria monocytogenes, Salmonella enterica and Escherichia coli) we tested and compared the performance of alternative viability test methods based on membrane permeability: propidium monoazide quantitative PCR (PMA-qPCR) and flow cytometry (FCM). Results were compared based on plate counts and fluorescent microscopy measurements, which showed that the former dramatically reduced the number of cultivable cells by more than 5 log units. Conversely, FCM provided a much more detailed picture of the process, as it directly quantifies the number of total cells and distinguishes among three categories, including intact, partially permeabilized and permeabilized cells. A comparison of both PMA-qPCR and FCM with plate count data indicated that only a fraction of intact cells maintained the ability to replicate in vitro. Following SC-CO2 treatment, FCM analysis revealed a markedly higher level of bacterial membrane permeabilization of L. monocytogenes with respect to E. coli and S. enterica. Furthermore, an intermediate permeabilization state in which the cellular surface was altered and biovolume increased up to 1.5-fold was observed in L. monocytogenes, but not in E. coli or S. enterica. FCM thus compared favourably with other methods and should be considered as an accurate analytical tool for applications in which monitoring bacterial viability status is of importance, such as microbiological risk assessment in the food chain or in the environment.

Clinical populations of Pseudomonas aeruginosa isolated from acute infections show a wide virulence range partially correlated with population structure and virulence gene expression.

Pseudomonas aeruginosa is a ubiquitous environmental bacterium responsible for a variety of infections in humans, as well as in animal hosts. While the evolution of virulence in P. aeruginosa strains isolated from chronic lung infection in cystic fibrosis (CF) patients has been extensively studied, the virulence phenotype of P. aeruginosa isolated from other infection types or from the environment is currently not well characterized. Here we report an extensive analysis of the virulence of P. aeruginosa strains isolated from acute infections compared with population structure. Virulence profiles of individual strains were also compared with the expression levels of the rhlR gene, the transcriptional regulator of the rhl quorum-sensing system, and the gene encoding Crc, a global regulator controlling catabolite repression and carbon metabolism. Additionally, the presence/absence of the two mutually exclusive genes, exoU and exoS, encoding effectors of the type III secretion system, was assessed. In order to capture the widest range of genetic variability, a collection of 120 clinical strains was initially characterized by repetitive element-based PCR genotyping, and a selection of 27 strains belonging to different clonal lineages was subsequently tested using three different virulence assays, including two Dictyostelium discoideum assays on different growth media, and a Caenorhabditis elegans fast-killing assay. We show that the parallel application of virulence assays can be used to quantitatively assess this complex, multifactorial phenotypic trait. We observed a wide spectrum of virulence phenotypes ranging from weakly to highly aggressive, indicating that clinical strains isolated from acute infections can present a reduced or altered virulence phenotype. Genotypic associations only partially correlated with virulence profiles and virulence gene expression, whereas the presence of either exoU or exoS was not significantly correlated with virulence. Interestingly, the expression of rhlR showed a significant and positive correlation with the virulence profiles obtained with the three assays, while the expression of crc was either negatively or not correlated with virulence, depending on the assay.