Function and Biogenesis of Lipopolysaccharides

Selenomethionine attenuates Klebsiella pneumoniae-induced jejunal injury in rabbits by inhibiting the TLR4/NF-κB pathway

Klebsiella pneumoniae (KP) infection often causes diarrhoea and intestinal barrier damage in young rabbits. The objective of this study was to explore whether selenomethionine (SeMet) can attenuate the jejunal injury caused by KP in rabbits. Therefore, we investigated the protective effect of SeMet by performing haematoxylin-eosin (HE), alcian blue periodic acid Schiff (AB-PAS), proliferating nuclear antigen (PCNA), TUNEL and immunofluorescence staining. In addition, the concentrations of Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Tumor necrosisfactor-α (TNF-α) and Interleukin-10 (IL-10) in the jejunal tissue were detected by enzyme-linked immunosorbent assay (ELISA). The results showed that after KP infection, the productivity of rabbits decreased, and the mucosal barrier of the jejunum was damaged. Moreover, KP induced jejunal inflammation, activated the TLR4/NF-κB signalling pathway, and promoted the expression of the IL-1β, IL-6, and TNF-α. In addition, KP increased the apoptotic response of intestinal cells and upregulated the expression of caspase-3 and caspase-9. SeMet pretreatment significantly decreased the degree of intestinal epithelial cell apoptosis. Therefore, we showed that SeMet can reduce inflammation and enhance intestinal barrier function to improve the production performance of rabbits infected with KP.

Rapid identification of key antibiotic resistance genes in E. coli using high-resolution genome-scale CRISPRi screening

Bacteria possess a vast repertoire of genes to adapt to environmental challenges. Understanding the gene fitness landscape under antibiotic stress is crucial for elucidating bacterial resistance mechanisms and antibiotic action. To explore this, we conducted a genome-scale CRISPRi screen using a high-density sgRNA library in Escherichia coli exposed to various antibiotics. This screen identified essential genes under antibiotic-induced stress and offered insights into the molecular mechanisms underlying bacterial responses. We uncovered previously unrecognized genes involved in antibiotic resistance, including essential membrane proteins. The screen also underscored the importance of transcriptional modulation of essential genes in antibiotic tolerance. Our findings emphasize the utility of genome-wide CRISPRi screening in mapping the genetic landscape of antibiotic resistance. This study provides a valuable resource for identifying potential targets for antibiotics or antimicrobial strategies. Moreover, it offers a framework for exploring transcriptional regulatory networks and resistance mechanisms in E. coli and other bacterial pathogens.

A combined in silico and MD simulation approach to discover novel LpxC inhibitors targeting multiple drug resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa), a member of the ESKAPE family, is the major cause of infections leading to increased morbidity and mortality due to multidrug resistance (MDR). One of the main proteins involved in the Raetz pathway is LpxC, which plays a significant role in anti-microbial resistance (AMR). Our study aimed to identify a novel compound to combat MDR due to the LpxC protein. It involved in silico methods comprising molecular docking, simulations, ADMET profiling, and DFT calculations. First, an ADMET and bioactivity evaluation of the 25 top-hit compounds retrieved from ligand-based virtual screening was performed, followed by molecular docking. The results revealed compound P-2 as the lead compound, which was further subjected to DFT analysis and molecular dynamics (MD) simulations. With these analyses, our in silico study identified P-2, 3-[(dimethylamino)methyl]-N-[(2 S)-1-(hydroxyamino)-1-oxobutan-2-yl]benzamide as a potential lead compound that may behave as a very potent inhibitor of LpxC for the development of targeted therapies against MDR P. aeruginosa.

Piezo1 activation protects against sepsis-induced myocardial dysfunction in a pilot study

To explore the role and underlying mechanisms of Piezo1 in sepsis-induced myocardial dysfunction (SIMD). A SIMD model was established in mice via intraperitoneal lipopolysaccharide (LPS) injection. Cardiac function, histology, Piezo1 protein expression, and cardiac troponin T (cTnT) were assessed. Piezo1's role in SIMD was investigated using the agonist Yoda1, inhibitor GsMTx-4, and cardiomyocyte-specific Piezo1 knockout (Piezo1ΔCM) mice. Dual Specificity Phosphatase 3 (DUSP3) protein levels were also assessed to explore potential mechanisms. SIMD mice exhibited significantly impaired cardiac function, along with increased Piezo1 protein and cTnT levels. Piezo1 activation improved cardiac function and reduced tissue damage, while inhibition worsened SIMD. Piezo1ΔCM mice exhibited more severe cardiac dysfunction and injury, especially with LPS treatment. DUSP3 protein levels were significantly elevated in Piezo1ΔCM and LPS-treated hearts. Piezo1 exerted a protective role in SIMD, potentially through the modulation of DUSP3.

Bactericidal activity of mammalian histones is caused by large membrane pore formation

Histones have an important role in eukaryotic innate immunity, wherein histones co-localize with antimicrobial peptides (AMPs). The mechanism of histone cooperation with AMPs and the extent to which histones form pores both remain a mystery. Here, we show that histones form large pores in bacterial membranes that lack lipopolysaccharide (LPS) and that their antimicrobial effect is significantly stronger than that of the clinical AMP polymyxin B. We find that histones and AMPs together produce potent antimicrobial synergy through the formation of 26 nm pores, whereby the pore-forming activity of AMPs on LPS-containing membranes enables histones to enter the periplasmic space and subsequently attack unprotected membranes to create pores. We provide a mechanistic explanation for the long-standing observations of histone antimicrobial activity and demonstrate how antimicrobial synergy arises. The ubiquity of histones and AMPs in innate immunity has significant implications for organismal defense and can be leveraged for novel antibiotic strategies.

Identifying potential novel widespread determinants of bacterial pathogenicity using phylogenetic-based orthology analysis

Introduction

The global rise in antibiotic resistance and emergence of new bacterial pathogens pose a significant threat to public health. Novel approaches to uncover potential novel diagnostic and therapeutic targets for these pathogens are needed.

Methods

In this study, we conducted a large-scale, phylogenetic-based orthology analysis (OA) to compare the proteomes of pathogenic to humans (HP) and non-pathogenic to humans (NHP) bacterial strains across 734 strains from 514 species and 91 families.

Results

Using a dedicated workflow, we identified 4,383 hierarchical orthologous groups (HOGs) significantly associated with the HP label, many of which are linked to critical factors such as stress tolerance, metabolic versatility, and antibiotic resistance. Both known virulence factors (VFs) and potential novel widespread pathogenicity determinants were uncovered, supported by both statistical testing and complementary protein domain analysis.

Discussion

By integrating curated strain-level pathogenicity annotations from BacSPaD with phylogeny-based OA, we introduce a novel approach and provide a novel resource for bacterial pathogenicity research.

Indole-3-Carbinol Mechanisms Combating Chemicals and Drug Toxicities

The toxicity of chemicals and drugs is a common crisis worldwide. Therefore, the search for protective compounds is growing. Natural compounds such as indole-3-carbinol (I3C) derived from cruciferous vegetables are preferred since they are safe for humans and the environment. This review focuses on I3C potential role in preventing and repairing damage caused by chemicals and drugs. Interestingly, I3C ameliorates hepatotoxicity induced by carbon tetrachloride (CCl4), diethylnitrosamine (DENA), alcohol, gold nanoparticles, and microbial toxins. Additionally, it inhibits carcinogenesis induced by different chemicals and prevents the deleterious effects of different antineoplastic drugs including cisplatin, doxorubicin (DOX), and trabectidin on normal tissues. Moreover, it reduces fetal malformation and protects against micronuclei formation and calstogenecity induced by cyclophosphamide (CP) in bone marrow cells. It also attenuates methotrexate (MTX)-induced hepatotoxicity, mitigates neurotoxicity caused by thioacetamide and clonidine, and protects against aspirin side effects in gastric mucosa. Furthermore, its nanoparticles inhibit neuronal damage caused by glutamate and rotenone. Thus, I3C prevents the toxicities caused by chemicals in the surrounding environment as well as those of consumed drugs.

Surface-mediated bacteriophage defense incurs fitness tradeoffs for interbacterial antagonism

Bacteria in polymicrobial habitats are constantly exposed to biotic threats from bacteriophages (or "phages"), antagonistic bacteria, and predatory eukaryotes. These antagonistic interactions play crucial roles in shaping the evolution and physiology of bacteria. To survive, bacteria have evolved mechanisms to protect themselves from such attacks, but the fitness costs of resisting one threat and rendering bacteria susceptible to others remain unappreciated. Here, we examined the fitness consequences of phage resistance in Salmonella enterica, revealing that phage-resistant variants exhibited significant fitness loss upon co-culture with competitor bacteria. These phage-resistant strains display varying degrees of lipopolysaccharide (LPS) deficiency and increased susceptibility to contact-dependent interbacterial antagonism, such as the type VI secretion system (T6SS). Utilizing mutational analyses and atomic force microscopy, we show that the long-modal length O-antigen of LPS serves as a protective barrier against T6SS-mediated intoxication. Notably, this competitive disadvantage can also be triggered independently by phages possessing LPS-targeting endoglycosidase in their tail spike proteins, which actively cleave the O-antigen upon infection. Our findings reveal two distinct mechanisms of phage-mediated LPS modifications that modulate interbacterial competition, shedding light on the dynamic microbial interplay within mixed populations.

Progress in Characterization of Lipopolysaccharides and Lipid A by Mass Spectrometry

Lipopolysaccharides (LPS) are complex molecules embedded in the outer membrane of Gram-negative bacteria. LPS are highly heterogeneous across species and strains, posing a significant analytical challenge. This review article explores recent advances in the identification and characterization of LPS, with a particular focus on the role of mass spectrometry (MS) techniques. The review highlights how MS, in conjunction with various separation methods and spanning different ionization techniques and dissociation modes, has enabled more precise and sensitive determination of LPS composition, with a focus on lipid A structure. Finally, emerging trends in MS applications for LPS research are discussed and its potential to provide deeper insights into the development of antibiotic resistance among pathogenic bacteria.

Fasting-induced ketogenesis sensitizes bacteria to antibiotic treatment

Fasting metabolism is a commonly observed motivational response to acute infections and is conceptualized as being beneficial for host survival. Here, we show that fasting potentiates antibiotic treatment for murine sepsis caused by Salmonella Typhimurium, Klebsiella pneumoniae, and Enterobacter cloacae, resulting in increased bacterial clearance and improved host immune responses and survival. This effect is mediated by fasting-induced ketogenesis and could be alternatively implemented by combination therapy with antibiotics and ketone bodies. We show that the ketone body acetoacetate is an effector that sensitizes bacteria to antibiotic treatment by increasing antibiotic lethality and outer and inner membrane permeability. Our results demonstrate that acetoacetate depletes bacterial amino acids, particularly positively charged amino acids and putrescine, leading to cell membrane malfunctions and redox-related lethality. This study reveals an unrecognized role of ketogenesis in antibiotic treatment and a potential ketone body-based treatment strategy for bacterial sepsis.

Optimal functioning of the Lpt bridge depends on a ternary complex between the lipocalin YedD and the LptDE translocon

The outer membrane is an efficient permeability barrier that protects gram-negative bacteria against external assaults, including many antibiotics. The unique permeability features of the outer membrane are due to the presence of lipopolysaccharide (LPS) molecules in its outer leaflet. LPS transport relies on the essential lipopolysaccharide transport (Lpt) pathway, which forms a bridge from the inner to the outer membrane. The LptDE translocon inserts LPS into the outer leaflet. Here, we identify the lipocalin YedD as a component of the translocon. Cryoelectron microscopy of the YedD-LptDE complex reveals that YedD binds LptD at a critical interface between its β-barrel and periplasmic β-taco domain. The YedD-LptDE complex is functionally relevant: under conditions where the connectivity of the β-taco and Lpt bridge is compromised, the absence of YedD decreases cell viability and causes LPS accumulation in the inner membrane. Our findings establish YedD as an Lpt component required for optimal LPS transport.

Recent insights into Wzy polymerases and lipopolysaccharide O-antigen biosynthesis

Bacteria synthesize a plethora of complex surface-associated polysaccharides which enable them to persist and thrive in distinct niches. These glycans serve an array of purposes pertaining to virulence, colonization, antimicrobial resistance, stealth, and biofilm formation. The Wzx/Wzy-dependent pathway is universally the predominant system for bacterial polysaccharide synthesis. This system is responsible for the production of lipopolysaccharide (LPS) O-antigen (Oag), enterobacterial common antigen, capsule, and exopolysaccharides, with orthologs present in both Gram-negative and Gram-positive microbes. Studies focusing principally on Pseudomonas, Shigella, and Salmonella LPS Oag synthesis have provided much of the framework underpinning the biochemical and molecular mechanism behind polysaccharide synthesis via this pathway. LPS Oag production via the Wzx/Wzy-dependent pathway occurs through the stepwise activity of multiple key biosynthetic enzymes, including primarily the polymerase, Wzy, which is responsible for the Oag assembly, and the polysaccharide co-polymerase, Wzz, which effectively modulates the length of the glycan produced. In this review, we provide a comprehensive summary of the latest genetic, structural, and mechanistic data for the main protein candidates of the Wzx/Wzy-dependent pathway, in addition to an examination of their substrate specificities. Furthermore, we have reviewed recent insights pertaining to the dynamics/kinetics of glycan synthesis by this mechanism, including the interplay of the key proteins among themselves and in complex with their substrate. Lastly, we outline key gaps in the literature and suggest future research avenues, with the aim to stimulate ongoing research into this critical pathway responsible for the production of key virulence factors for numerous debilitating and lethal pathogens.

Clinical characteristics and risk factors of late-stage lung adenocarcinoma patients with bacterial pulmonary infection and its relationship with cellular immune function

Background

To research the clinical characteristics, risk factors, the correlation between bacterial pulmonary infection and immune function of advanced lung adenocarcinoma patients complicated with bacterial pulmonary infection.

Methods

334 stage III and IV lung adenocarcinoma patients admitted to the first affiliated hospital of Zhengzhou University from January 2020 to March 2023 were selected and divided into an infection group (n = 240) and a control group (n= 72) according to whether complicated with bacterial pulmonary infection. The clinical characteristics were analyzed. The pulmonary microbiota and human T lymphocyte subsets (CD3+, CD4+, CD8+) were detected. Multivariate logistic regression analysis was performed to explore the risk factors for pulmonary bacterial infection in advanced lung adenocarcinoma patients.

Results

Among 334 patients, 264 cases were complicated with pulmonary bacterial infection, and 70 cases had no pulmonary bacterial infection. In total, 544 pathogenic bacteria were isolated from the patients. Of these, 170 strains (31.25%) were Gram-negative bacilli, 162 strains (29.78%) were Gram-positive cocci, 27 strains (4.96%) Gram-positive bacilli. There were statistically significant differences in age, smoking, combined diseases, TNM staging, CD3+ T cell percentage, and CD4+ T cell percentage between the two groups (P < 0.05). Multivariate logistic regression analysis revealed smoking, bronchiectasis, and diabetes were independent risk factors leading to late-stage lung adenocarcinoma patients with bacterial pulmonary infection (P < 0.05). In those patients on immune checkpoint inhibitors, the lung Gram-positive group has a higher number of CD4+ T cells and CD4+/CD8+ T cell ratio than the Gram-negative group (P < 0.05).

Conclusion

Smoking, bronchiectasis, and diabetes are risk factors for lung bacterial infection in patients with advanced lung adenocarcinoma. The effect of immune checkpoint inhibitor treatment on T cells is more pronounced in Gram positive bacteria.

In silico analysis of zosurabalpin-LptB2FG binding in Acinetobacter spp., Klebsiella pneumoniae, and Shigella flexneri: mechanisms underlying its differential efficacy

Zosurabalpin, a novel tethered macrocyclic peptide antibiotic, exhibits potent activity against Acinetobacter spp., particularly carbapenem-resistant Acinetobacter baumannii (CRAB). Zosurabalpin inhibits lipopolysaccharide (LPS) transport by targeting the LptB2FG protein complex, resulting in toxic LPS accumulation and bacterialdeath. This study investigates zosurabalpin's molecular specificity against Acinetobacter spp., its ineffectiveness against Klebsiella pneumoniae, and its potential efficacy against Shigella flexneri. Comparative analysis of LptB2FG sequences and structures, revealed significant differences in LptB2FG protein conformations, pocket geometry and electrostatic surface surrounding the binding pocket among the three species, which may influence zosurabalpin binding. Docking results for zosurabalpin showed lower binding affinities for K. pneumoniae and S. flexneri compared to Acinetobacter baylyi. Additionally, other zosurabalpin derivatives were tested showing improved binding affinities for K. pneumoniae but not for S. flexneri. These findings underscore the need for tailored zosurabalpin derivatives to enhance efficacy against a broader spectrum of Gram-negative bacteria.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-025-00343-3.

Microbiota-induced inflammation mediates the impacts of a Western diet on hippocampal-dependent memory

Obesity is associated with impaired hippocampal-dependent memory, but the mechanisms driving this pathology are not fully understood. Western diets (WD) contribute to obesity, and previous reviews have described a role for WD in impaired hippocampal-dependent memory. However, there is need for a more detailed description of the pathways by which WD may impair memory. The short vs long-term effect of specific dietary components on brain structure and functions as well as the precise mechanism and molecular pathways involved are still not fully understood. This review focuses on the mechanisms and effects of gut microbiota-driven neuroinflammation. WD leads to changes and imbalance in bacterial taxa abundances that are deleterious to the host health (gut dysbiosis) and studies in rodent models show these changes are sufficient to impair hippocampal-dependent memory. Here, we discuss a variety of proposed mechanisms linking microbiota composition to hippocampal function, with a focus on neuroinflammation. Gut microbiota impacts gastrointestinal barrier function, leading to increased circulating proinflammatory bacterial products, increased blood-brain barrier permeability, and neuroinflammation.

Functional and structural characterization of Staphylococcus aureus N-acetylglucosamine 1-phosphate uridyltransferase (GlmU) reveals a redox-sensitive acetyltransferase activity

The bifunctional enzyme N-acetylglucosamine 1-phosphate uridyltransferase (GlmU) is a promising antibiotic drug target, as it facilitates the biosynthesis of uridine 5'-diphospho-N-acetylglucosamine, an essential precursor of cell wall constituents. We identified that Staphylococcus aureus GlmU (SaGlmU), which was previously targeted for inhibitor development, possesses a dual-cysteine variation (C379/C404) within the acetyltransferase active site. Enzyme assays performed under reducing and non-reducing conditions revealed that the acetyltransferase activity of SaGlmU is redox-sensitive, displaying ~15-fold lower turnover and ~3-fold higher KM value for the acetyl CoA substrate under non-reducing conditions. This sensitivity was absent in a C379A SaGlmU mutant. Analysis of SaGlmU by mass spectrometry, x-ray crystallography, and in silico modeling support that C379 and C404 act as a reversible, redox-sensitive switch by forming a disulfide under non-reducing conditions that impedes acetyl CoA recognition and turnover. Therefore, we recommend that future in vitro screening and characterization of SaGlmU inhibitors consider both reducing and non-reducing conditions.

Completing the BASEL phage collection to unlock hidden diversity for systematic exploration of phage-host interactions

Research on bacteriophages, the viruses infecting bacteria, has fueled the development of modern molecular biology and inspired their therapeutic application to combat bacterial multidrug resistance. However, most work has so far focused on a few model phages which impedes direct applications of these findings in clinics and suggests that a vast potential of powerful molecular biology has remained untapped. We have therefore recently composed the BASEL collection of Escherichia coli phages (BActeriophage SElection for your Laboratory), which made a relevant diversity of phages infecting the E. coli K-12 laboratory strain accessible to the community. These phages are widely used, but their assorted diversity has remained limited by the E. coli K-12 host. We have therefore now genetically overcome the two major limitations of E. coli K-12, its lack of O-antigen glycans and the presence of resident bacterial immunity. Restoring O-antigen expression resulted in the isolation of diverse additional viral groups like Kagunavirus, Nonanavirus, Gordonclarkvirinae, and Gamaleyavirus, while eliminating all known antiviral defenses of E. coli K-12 additionally enabled us to isolate phages of Wifcevirus genus. Even though some of these viral groups appear to be common in nature, no phages from any of them had previously been isolated using E. coli laboratory strains, and they had thus remained largely understudied. Overall, 37 new phage isolates have been added to complete the BASEL collection. These phages were deeply characterized genomically and phenotypically with regard to host receptors, sensitivity to antiviral defense systems, and host range. Our results highlighted dominant roles of the O-antigen barrier for viral host recognition and of restriction-modification systems in bacterial immunity. We anticipate that the completed BASEL collection will propel research on phage-host interactions and their molecular mechanisms, deepening our understanding of viral ecology and fostering innovations in biotechnology and antimicrobial therapy.

(p)ppGpp and DksA play a crucial role in reducing the efficacy of β-lactam antibiotics by modulating bacterial membrane permeability

The key signaling molecules in the bacterial stress-sensing pathway, the alarmone (p)ppGpp and the transcription factor DksA, play a crucial role in bacterial survival during nutritional deprivation and exposure to xenobiotics by modulating cellular metabolic pathways. In Vibrio cholerae, (p)ppGpp metabolism is solely linked with the functions of three proteins: RelA, SpoT, and RelV. The effects of threshold or elevated concentrations of (p)ppGpp on cellular metabolites and proteins, both in the presence and absence of DksA, have not yet been comprehensively studied in V. cholerae or other bacteria. We engineered the genome of V. cholerae to develop DksA null mutants in the presence and absence of (p)ppGpp biosynthetic enzymes. We observed that the N16:ΔrelAΔrelVΔspoTΔdksA V. cholerae mutant, which lacks both (p)ppGpp and DksA, exhibits higher sensitivity to different ꞵ-lactam antibiotics compared with the wild-type (WT) strain. Our whole-cell metabolomic and proteome analysis revealed that the cell membrane and peptidoglycan biosynthesis pathways are significantly altered in the N16:ΔrelAΔrelVΔspoT, N16:ΔdksA, and N16:ΔrelAΔrelVΔspoTΔdksA V. cholerae strains. Furthermore, the mutant strains displayed enhanced inner and outer membrane permeabilities in comparison to the WT strains. These results correlate with V. cholerae's tolerance and survival against β-lactam antibiotics and may inform the development of adjuvants that inhibit stringent response modulators.IMPORTANCEThe (p)ppGpp biosynthetic pathway is widely conserved in bacteria. Intracellular levels of (p)ppGpp and the transcription factor DksA play crucial roles in bacterial multiplication and viability in the presence of antibiotics and/or other xenobiotics. The present findings have shown that (p)ppGpp and DksA significantly reduce the efficacy of ꞵ-lactam and other antibiotics by modulating the availability of peptidoglycan and cell membrane-associated metabolites by reducing membrane permeability. Nevertheless, the whole-cell proteome analysis of N16:ΔrelAΔrelVΔspoT, N16:ΔdksA, and N16:ΔrelAΔrelVΔspoTΔdksA strains identified the biosynthetic pathways and associated enzymes that are directly modulated by the stringent response effector molecules. Thus, the (p)ppGpp metabolic pathways and DksA could be a potential target for increasing the efficacy of antibiotics and developing antibiotic adjuvants.

O-antigen of uropathogenic Escherichia coli is required for induction of neutrophil extracellular traps

BACKGROUND

Urinary tract infections (UTIs) are prevalent bacterial infection, with uropathogenic Escherichia coli (UPEC) as the primary causative agent. The outer membrane of UPEC contains a lipopolysaccharide (LPS), which plays crucial roles in the host's immune response to infection. Neutrophils use neutrophil extracellular traps (NETs) are mechanism by which neutrophils defend against bacterial infections. However, the exact mechanism by which a bacterial LPS induces NET formation is not well understood. Therefore, the objective of this study is to identify the possible mechanism of LPS-mediated NETs and dissect the LPS domains of UPEC that predominantly modulate NET formation and NET-mediated killing.

METHODS

To investigate the mechanism of bacterial LPS-induced NET formation, we constructed UPEC CFT073 mutants that had rfaD, rfaL and the wzzE deleted with individual LPS biosynthetic genes including the inner core synthase, O-antigen ligase and O-antigen polymerase, respectively. Subsequently, we evaluated the NET/reactive oxygen species (ROS)/IL-1β induction abilities and assessed the activation of toll-like receptor 4 (TLR4)/JNK signaling by CFT073 and its mutants.

RESULTS

The results showed that the O-antigen of CFT073 LPS is essential for inducing NET formation through TLR4/JNK/NOX pathways. Inhibition of either pathway significantly decreased the production of ROS, induction of NETs, and secretion of IL-1β.

CONCLUSION

Our results demonstrate that CFT073 LPS is essential for inducing ROS-dependent NETs and IL-1β secretion from neutrophils. This study also provides evidence for the crucial roles of O-antigen in the immune response to UPEC infection, as well as its potential as a therapeutic target for the treatment of UTIs.

Maternal balanced energy-protein supplementation reshapes the maternal gut microbiome and enhances carbohydrate metabolism in infants: a randomized controlled trial

Balanced energy-protein (BEP) supplementation during pregnancy and lactation can improve birth outcomes and infant growth, with the gut microbiome as a potential mediator. The MISAME-III randomized controlled trial (ClinicalTrial.gov: NCT03533712) assessed the effect of BEP supplementation, provided during pregnancy and the first six months of lactation, on small-for-gestational age prevalence and length-for-age Z-scores at six months in rural Burkina Faso. Nested within MISAME-III, this sub-study examines the impact of BEP supplementation on maternal and infant gut microbiomes and their mediating role in birth outcomes and infant growth. A total of 152 mother-infant dyads (n = 71 intervention, n = 81 control) were included for metagenomic sequencing, with stool samples collected at the second and third trimesters, and at 1-2 and 5-6 months postpartum. BEP supplementation significantly altered maternal gut microbiome diversity, composition, and function, particularly those with immune-modulatory properties. Pathways linked to lipopolysaccharide biosynthesis were depleted and the species Bacteroides fragilis was enriched in BEP-supplemented mothers. Maternal BEP supplementation also accelerated infant microbiome changes and enhanced carbohydrate metabolism. Causal mediation analyses identified specific taxa mediating the effect of BEP on birth outcomes and infant growth. These findings suggest that maternal supplementation modulates gut microbiome composition and influences early-life development in resource-limited settings.

Expanded Gram-Negative Activity of Marinopyrrole A

The rise of bacterial infections is a global health issue that calls for the development and availability of additional antimicrobial agents. Known for its in vitro effects on Gram-positive organisms, the drug-like small molecule marinopyrrole A was re-examined for the potential of broader efficacy against a wider array of microbes. We uncovered selective efficacy against an important subset of Gram-negative bacteria from three genera: Neisseria, Moraxella, and Campylobacter. This susceptibility is correlated with the absence of canonical LPS in these specific Gram-negative species, a phenomenon observed with other hydrophobic anti-microbial compounds. Further, when exposed to molecules which inhibit the LpxC enzyme of the LPS synthesis pathway, previously resistant LPS-producing Gram-negative bacteria showed increased susceptibility to marinopyrrole A. These results demonstrate marinopyrrole A's efficacy against a broader range of Gram-negative bacteria than previously known, including N. gonorrhea, a species identified as a priority pathogen by the WHO.

Fighting Antimicrobial Resistance: Innovative Drugs in Antibacterial Research

In the fight against bacterial infections, particularly those caused by multi-resistant pathogens known as "superbugs", the need for new antibacterials is undoubted in scientific communities and is by now also widely perceived by the general population. However, the antibacterial research landscape has changed considerably over the past years. With few exceptions, the majority of big pharma companies has left the field and thus, the decline in R&D on antibacterials severely impacts the drug pipeline. In recent years, antibacterial research has increasingly relied on smaller companies or academic research institutions, which mostly have only limited financial resources, to carry a drug discovery and development process from the beginning and through to the beginning of clinical phases. This review formulates the requirements for an antibacterial in regard of targeted pathogens, resistance mechanisms and drug discovery. Strategies are shown for the discovery of new antibacterial structures originating from natural sources, by chemical synthesis and more recently from artificial intelligence approaches. This is complemented by principles for the computer-aided design of antibacterials and the refinement of a lead structure. The second part of the article comprises a compilation of antibacterial molecules classified according to bacterial target structures, e.g. cell wall synthesis, protein synthesis, as well as more recently emerging target classes, e.g. fatty acid synthesis, proteases and membrane proteins. Aspects of the origin, the antibacterial spectrum, resistance and the current development status of the presented drug molecules are highlighted.

Gut microbiota-derived hexa-acylated lipopolysaccharides enhance cancer immunotherapy responses

The gut microbiome modulates immunotherapy treatment responses, and this may explain why immune checkpoint inhibitors, such as anti-PD-1, are only effective in some patients. Previous studies correlated lipopolysaccharide (LPS)-producing gut microbes with poorer prognosis; however, LPS from diverse bacterial species can range from immunostimulatory to inhibitory. Here, by functionally analysing faecal metagenomes from 112 patients with melanoma, we found that a subset of LPS-producing bacteria encoding immunostimulatory hexa-acylated LPS was enriched in microbiomes of clinical responders. In an implanted tumour mouse model of anti-PD-1 treatment, microbiota-derived hexa-acylated LPS was required for effective anti-tumour immune responses, and LPS-binding antibiotics and a small-molecule TLR4 antagonist abolished anti-PD-1 efficacy. Conversely, oral administration of hexa-acylated LPS to mice significantly augmented anti-PD-1-mediated anti-tumour immunity. Penta-acylated LPS did not improve anti-PD-1 efficacy in vivo and inhibited hexa-acylated LPS-induced immune activation in vitro. Microbiome hexa-acylated LPS therefore represents an accessible predictor and potential enhancer of immunotherapy responses.

Photocrosslinking and capture for the analysis of carbohydrate-dependent interactions

Carbohydrates play crucial roles in biological systems, including by mediating cell and protein interactions. The complexity and transient nature of carbohydrate-dependent interactions pose significant challenges for their characterization, as traditional techniques often fail to capture these low-affinity binding events. This review highlights the increasing utility of photocrosslinkers in studying carbohydrate-mediated interactions. Photocrosslinkers, such as aryl azides, benzophenones, and diazirines, allow for the capture of fleeting interactions by forming covalent bonds upon UV irradiation, enabling the downstream application of standard biochemical techniques. I discuss the three primary strategies for incorporating photocrosslinkers: synthetic small molecules, metabolic labeling, and exo-enzymatic labeling. I predict that the continued development and application of these methodologies will enhance our understanding of glycan-mediated interactions and their implications in health and disease.

Mechanisms of Salmonella typhimurium Resistance to Cannabidiol

The emergence of multi-drug resistance (MDR) poses a huge risk to public health globally. Yet these recalcitrant pathogens continue to rise in incidence rate with resistance rates significantly outpacing the speed of antibiotic development. This therefore presents related health issues such as untreatable nosocomial infections arising from organ transplants and surgeries, as well as community-acquired infections that are related to people with compromised immunity, e.g., diabetic and HIV patients, etc. There is a global effort to fight MRD pathogens spearheaded by the World Health Organization, thus calling for research into novel antimicrobial agents to fight multiple drug resistance. Previously, our laboratory demonstrated that Cannabidiol (CBD) is an effective antimicrobial against Salmonella typhimurium (S. typhimurium). However, we observed resistance development over time. To understand the mechanisms S. typhimurium uses to develop resistance to CBD, we studied the abundance of bacteria lipopolysaccharide (LPS) and membrane sterols of both CBD-susceptible and CBD-resistant S. typhimurium strains. Using real-time quantitative polymerase chain reaction (rt qPCR), we also analyzed the expression of selected genes known for aiding resistance development in S. typhimurium. We found a significantly higher expression of blaTEM (over 150 mRNA expression) representing over 55% of all the genes considered in the study, fimA (over 12 mRNA expression), fimZ (over 55 mRNA expression), and integron 2 (over 1.5 mRNA expression) in the CBD-resistant bacteria, and these were also accompanied by a shift in abundance in cell surface molecules such as LPS at 1.76 nm, ergosterols at 1.03 nm, oleic acid at 0.10 nm and MPPSE at 2.25nm. For the first time, we demonstrated that CBD-resistance development in S. typhimurium might be caused by several structural and genetic factors. These structural factors demonstrated here include LPS and cell membrane sterols, which showed significant differences in abundances on the bacterial cell surfaces between the CBD-resistant and CBD-susceptible strains of S. typhimurium. Specific key genetic elements implicated for the resistance development investigated included fimA, fimZ, int2, ompC, blaTEM, DNA recombinase (STM0716), leucine-responsive transcriptional regulator (lrp/STM0959), and the spy gene of S. typhimurium. In this study, we revealed that blaTEM might be the highest contributor to CBD-resistance, indicating the potential gene to target in developing agents against CBD-resistant S. typhimurium strains.

Determining the Bordetella LPS structural features that influence TLR4 downstream signaling

Upon recognizing bacterial lipopolysaccharide (LPS), human TLR4 initiates two distinct signaling pathways: the MyD88 pathway from the cell surface or the TRIF pathway following endocytosis. While the first is associated with strong pro-inflammatory responses, the latter is linked to dendritic cell maturation and T cell priming. Changes in LPS structure can influence the activation of either or both pathways. This study investigates the influence of specific structural features of Bordetella LPS on these pathways: the O antigen, the number of acyl chains in lipid A and the glucosamine modification of the phosphates of the lipid A diglucosamine backbone. Systematically engineered Bordetella LPS differing in one or more of these features were studied by quantifying NFκB and IRF3 activation-indicators of MyD88 and TRIF pathway activation, respectively. The findings reveal that the glucosamine modification of lipid A plays a dominant role in TLR4-mediated signaling, overriding the influence of the O antigen and lipid A acylation. The absence of glucosamine modification significantly reduced the activation of both MyD88 and TRIF pathways, underscoring its importance in promoting TLR4 dimerization. Furthermore, under-acylation of LPS (with 4 or 5 acyl chains) partially reduced NFκB activation, while completely abrogating TRIF pathway activation. In contrast, hexa-and hepta-acylated LPS equally and robustly activated both pathways. Lastly, the Bordetella O antigen selectively biased signaling towards the TRIF pathway without affecting the MyD88 pathway. This study provides valuable insights into how specific LPS structural modifications can be leveraged to tailor TLR4-mediated signaling.

Methyl-esterification, degree of polymerization and ∆4,5-unsaturation of galacturonic acid oligosaccharides as determinants of immunomodulation

In recent years, immunomodulation by pectin and pectin-derived galacturonic acid oligosaccharides has been the subject of wide-spread scientific research due to the potential of different pectin structures as bioactive biomolecules. Yet, gaps remain in understanding the structure-dependent immunomodulation of galacturonic acid. This study describes in vitro immunomodulatory effects of well-characterized galacturonic acid oligosaccharides. Both methyl-esterified and non-methyl-esterified galacturonic acid oligosaccharides with a saturated non-reducing end (degree of polymerization 1-10) significantly induced cytokine production by THP-1 macrophages and directly activated TLR2 and TLR4 in transfected HEK-293 cells, even when accounting for minor endotoxin contamination. In contrast, both methyl-esterified and non-methyl-esterified galacturonic acid oligosaccharides with a Δ4,5-unsaturated non-reducing end (degree of polymerization 1-7) did not activate TLR2 and TLR4 and led to significantly reduced cytokine production (p < 0.05), suggesting Δ4,5-(un)saturation as a pivotal factor for immunomodulation by galacturonic acid oligosaccharides. Exposure to non-methyl-esterified saturated galacturonic acid oligosaccharides resulted in significantly lower TNF-α production, IL-1β production and TLR4 activation (p < 0.05) compared to methyl-esterified saturated galacturonic acid oligosaccharides, while IL-10 production and TLR2 activation remained unchanged. These findings establish galacturonic acid oligosaccharides as versatile immunomodulators with TLR2 and TLR4 binding capacity, fit for different immunomodulatory applications depending on their structural characteristics.

Exploring the functional diversity and metabolic activities of the human gut microbiome in Thai adults in response to a prebiotic diet

Exploring dietary methods to alter microbial communities and metabolic functions is becoming an increasingly fascinating strategy for improving health. Copra meal hydrolysate (CMH) is alternatively used as a gut health supplement. However, the functional diversity and metabolic activities in gut microbiome in relation to CMH treatment remain largely unknown. Therefore, this study aimed to identify key predominant groups of bacterial species toward diversified metabolic functions, activities, and routes using metaproteomics. As a result, the integrative analysis of metaproteomic data revealed that seven key families across 11 dominant gut bacterial species were concerted. Consistently, across 76,206 proteins assigned to the metabolism of the 255,964 annotated proteins, short-chain fatty acid (SCFA) biosynthesis, lipopolysaccharide (LPS) biosynthesis, and bile acid (BA) metabolism were positively associated with CMH. Further identification of cooperative metabolic routes promisingly highlighted the importance of glycolysis/gluconeogenesis, tricarboxylic acid (TCA) cycle, inositol phosphate metabolism, steroid hormone biosynthesis, O-antigen repeat unit biosynthesis, and chloroalkane and chloroalkene degradation. This work presents an initial study of metaproteomics associated with prebiotic diet in a Thai population-based cohort in a developing Southeast Asian country.IMPORTANCEStudies primarily focused on the impact of CMH on gastrointestinal symptoms and gut microbial compositions. However, as the field moves toward understanding the relationship between microbiome and diet in relation to gut health, it is critical to evaluate how changes in metabolic activities relate to cooperative metabolic routes in the gut microbiome for promoting human health. Through the use of metaproteomics, our findings highlighted the key predominant groups of bacterial species, potential proteins, and their metabolic routes involved in gut metabolism. This study provides comprehensive insights into the fundamental relationship between microbiome and dietary supplements and suggests that metaproteomics is a powerful method for monitoring metabolic functions, activities, and routes in the gut microbiome.

mTOR/HIF-1α pathway-mediated glucose reprogramming and macrophage polarization by Sini decoction plus ginseng soup in ALF

BACKGROUND

Acute liver failure (ALF) has a high mortality rate, and despite treatment advancements, long-term outcomes remain poor.

PURPOSE

This study explores the therapeutic targets and pathways of Sini Decoction plus Ginseng Soup (SNRS) in ALF using bioinformatics and network pharmacology, focusing on its impact on macrophage polarization through glucose metabolism reprogramming. The efficacy of SNRS was validated in an LPS/D-GalN-induced ALF model, and its optimal concentration was determined for in vitro macrophage intervention.

STUDY DESIGN AND METHODS

Differentially expressed genes (DEGs) in HBV-induced and acetaminophen-induced ALF were identified from GEO datasets. The correlation between target gene expression and immune cell infiltration in ALF liver tissue was analyzed. AST, ALT, TNF-α, HMGB1, IL-1β, IL-6, and IL-10 levels were measured, and liver histopathology was assessed. Macrophage polarization was analyzed via immunofluorescence, flow cytometry, and Western blot. Glycolysis-related enzymes and metabolites, including HK2, PFK-1, PKM2, and LDHA, were quantified. Cellular ultrastructure was examined by transmission electron microscopy.

RESULTS

Five key glycolysis-regulating genes (HK2, CDK1, SOD1, VEGFA, GOT1) were identified, with significant involvement in the HIF-1 signaling pathway. Immune infiltration was markedly higher in ALF liver tissue. SNRS improved survival, reduced ALT/AST levels, alleviated liver injury, and modulated macrophage polarization by decreasing CD86 and increasing CD163 expression. In vitro, SNRS inhibited LPS-induced inflammatory cytokine release, lactate production, p-mTOR/mTOR ratio, and HIF-1α expression.

CONCLUSION

SNRS modulates macrophage polarization and glucose metabolism reprogramming via the mTOR/HIF-1α pathway, showing promise as a treatment for ALF.

A review on gut microbiota and miRNA crosstalk: implications for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline and progressive neuronal damage. Recent research has highlighted the significant roles of the gut microbiota and microRNAs (miRNAs) in the pathogenesis of AD. This review explores the intricate interaction between gut microbiota and miRNAs, emphasizing their combined impact on Alzheimer's progression. First, we discuss the bidirectional communication within the gut-brain axis and how gut dysbiosis contributes to neuroinflammation and neurodegeneration in AD. Changes in gut microbiota composition in Alzheimer's patients have been linked to inflammation, which exacerbates disease progression. Next, we delve into the biology of miRNAs, focusing on their roles in gene regulation, neurodevelopment, and neurodegeneration. Dysregulated miRNAs are implicated in AD pathogenesis, influencing key processes like inflammation, tau pathology, and amyloid deposition. We then examine how the gut microbiota modulates miRNA expression, particularly in the brain, potentially altering neuroinflammatory responses and synaptic plasticity. The interplay between gut microbiota and miRNAs also affects blood-brain barrier integrity, further contributing to Alzheimer's pathology. Lastly, we explore therapeutic strategies targeting this gut microbiota-miRNA axis, including probiotics, prebiotics, and dietary interventions, aiming to modulate miRNA expression and improve AD outcomes. While promising, challenges remain in fully elucidating these interactions and translating them into effective therapies. This review highlights the importance of understanding the gut microbiota-miRNA relationship in AD, offering potential pathways for novel therapeutic approaches aimed at mitigating the disease's progression.

Biomass-Derived Nanoporous Carbon Honeycomb Monoliths for Environmental Lipopolysaccharide Adsorption from Aqueous Media

After undergoing biological treatment, wastewater still contains substances with endotoxic activity, such as lipopolysaccharide. However, due to the increasing practice of treating wastewater to make it suitable for drinking (potable reuse), the removal of these endotoxic active materials is crucial. These substances can be harmful to human health, leading to a condition called endotoxaemia. Furthermore, environmental endotoxins pose risks to pharmaceutical manufacturing processes and the quality of the final pharmaceutical products. Ultimately, the most significant concern lies with the patient, as exposure to such substances can have adverse effects on their health and well-being. Activated carbon has a proven efficiency for endotoxin removal; rice husk (RH), as a type of natural lignocellulosic agricultural waste, is a unique carbon precursor material in terms of its availability, large-scale world production (over 140 million tons annually), and is characterized by the presence of nanoscale silica phytoliths, which serve as a template to create additional meso/macropore space within the nanoscale range. High surface area RH/lignin-derived honeycomb monoliths were prepared in this study via extrusion, followed by carbonization and physical and chemical activation to develop additional pore space. The nanoporosity of the carbon honeycomb monoliths was established by means of low-temperature nitrogen adsorption studies, using calculations based on QSDFT equilibrium and BJH models, as well as mercury intrusion porosimetry (MIP) and SEM investigations. An alternative method for the elimination of the bacterial lipopolysaccharide (LPS)-a conventional marker-using filtration in flowing recirculation systems and the adsorbent activity of the monoliths towards LPS was investigated. Since LPS expresses strong toxic effects even at very low concentrations, e.g., below 10 EU/mL, its removal even in minute amounts is essential. It was found that monoliths are able to eliminate biologically relevant LPS levels, e.g., adsorption removal within 5, 30, 60, 90, and 120 min of circulation reached the values of 49.8, 74.1, 85.4, 91.3%, and 91.6%, respectively.

Identifying Opportunity Targets in Gram-Negative Pathogens for Infectious Disease Mitigation

Antimicrobial drug resistance (AMR) is a pressing global human health challenge. Humans face one of their grandest challenges as climate change expands the habitat of vectors that bear human pathogens, incidences of nosocomial infections rise, and new antibiotics discovery lags. AMR is a multifaceted problem that requires a multidisciplinary and an "all-hands-on-deck" approach. As chemical microbiologists, we are well positioned to understand the complexities of AMR while seeing opportunities for tackling the challenge. In this Outlook, we focus on vulnerabilities of human pathogens and posit that they represent "opportunity targets" for which few modulatory ligands exist. We center our attention on proteins in Gram-negative organisms, which are recalcitrant to many antibiotics because of their external membrane barrier. Our hope is to highlight such targets and explore their potential as "druggable" proteins for infectious disease mitigation. We posit that success in this endeavor will introduce new classes of antibiotics that might alleviate some of the current pressing AMR concerns.

The Janus Effect: The Biochemical Logic of Antibiotic Resistance

Antibiotics are essential medicines threatened by the emergence of resistance in all relevant bacterial pathogens. The engagement of the molecular targets of antibiotics offers multiple opportunities for resistance to emerge. Successful target engagement often requires passage of the antibiotic from outside into the cell interior through one or two distinct membrane barriers. Resistance can occur by preventing the accumulation of antibiotics in sufficient quantities outside the cell, decreasing the rates of entry into the cell, and modifying the antibiotic or the target once inside the cell. These competing equilibria and rates are the lens through which the balance of antibiotic efficacy or failure can be viewed. The two faces of antibiotics, cell growth inhibition or resistance, are reminiscent of Janus, the Roman god of doorways and beginnings and endings, and offer a framework through which antibiotic discovery, use, and the emergence of resistance can be rationally viewed.

Airborne Escherichia coli bacteria biosynthesize lipids in response to aerosolization stress

Gram-negative bacteria pose an increased threat to public health because of their ability to evade the effects of many antimicrobials with growing antibiotic resistance globally. One key component of gram-negative bacteria resistance is the functionality and the cells' ability to repair the outer membrane (OM) which acts as a barrier for the cell to the external environment. The biosynthesis of lipids, particularly lipopolysaccharides, or lipooligosaccharides (LPS/LOS) is essential for OM repair. Here we show the phenotypic and genotypic changes of Escherichia coli MG1655 (E. coli) before and after exposure to short-term aerosolization, 5 min, and long-term indoor aerosolization, 30 min. Short-term aerosolization samples exhibited major damages to the OM and resulted in the elongation of the cells. Long-term aerosolization seemed to lead to cell lysis and aggregation of cell material. Disintegrated OM rendered some of the elongated cells susceptible to cytoplasmic leakage and other damages. Further analysis of the repairs the E. coli cells seemed to enact after short-term aerosolization revealed that the repair molecules were likely lipid-containing droplets that perfectly countered the air pressure impacting the E. coli cells. If lipid biosynthesis to counter the pressure is inhibited in bacteria that are exposed to environmental conditions with high air velocity, the cells would lyse or be exposed to more toxins and thus become more susceptible to antimicrobial treatments. This article is the first to show lipid behavior in response to aerosolization stress in airborne bacteria both genotypically and phenotypically. Understanding the relationship between environmental conditions in ventilated spaces, lipid biosynthesis, and cellular responses is crucial for developing effective strategies to combat bacterial infections and antibiotic resistance. By elucidating the repair mechanisms initiated by E. coli in response to aerosolization, this study contributes to the broader understanding of bacterial adaptation and vulnerability under specific environmental pressures. These insights may pave the way for novel therapeutic approaches that target lipid biosynthesis pathways and exploit vulnerabilities in bacterial defenses, ultimately improving treatment outcomes.

Oxidative Challenges Do Not Impact Pheomelanin-Dependent Coloration in Male Japanese Quails

Colorful traits play an important role in animal communication. Melanin-based colorations are the most extended color traits in animals and are produced by two types of endogenous melanic pigments: eumelanins and pheomelanins, the last ones being the least studied in the context of communication. The production of pheomelanin requires a semi-essential amino acid, cysteine, which is also used for the synthesis of an important endogenous antioxidant, glutathione. Hence, it has been proposed that the synthesis of pheomelanin and glutathione may compete for the cysteine available in the organism. In that case, pheomelanic colorations are predicted to be less intense when the individual is facing an oxidative challenge, and therefore, they would provide information on the oxidative status of the bearer. Here, we experimentally evaluated this hypothesis using male Japanese quails (Coturnix japonica) as a model of study, a species with pheomelanin-based plumage in the breast and cheeks. During feather growth, individuals were exposed to one of three possible conditions: Control (saline), an endogenous oxidative challenge (Escherichia coli lipopolysaccharide injections), or an exogenous oxidative challenge (paraquat injections). Contrary to predictions, we found that: (1) Birds from the three groups exhibited less intense pheomelanic colorations in feathers after the experimental manipulation, and the magnitude of this change did not differ among groups. (2) There was no effect of the experimental treatments on the proportion reduced/oxidized glutathione, an index of oxidative status. (3) Lipid peroxidation was lower after the experimental manipulation, with birds exposed to the paraquat challenge experiencing a stronger decline than other groups. (4) Cysteine and total glutathione levels decreased after the experimental manipulation, with no differences per group in the magnitude of the decline. Taken together the results do not support the hypothesis that oxidative status plays a key role at determining the variation in the intensity of pheomelanic colorations.

Mustard Meal Extract as an Alternative to Zinc Oxide for Protecting the Intestinal Barrier Against E. coli-Lipopolysaccharide Damage

The present study aimed to investigate the ability of an aqueous extract derived from mustard seed meal to counteract the effects of E. coli endotoxin lipopolysaccharide (LPS) on the intestinal epithelium. Caco-2 cells were cultured together with HT29-MTX and used as a cellular model to analyze critical intestinal parameters, such as renewal, integrity, innate immunity, and signaling pathway. Byproducts of mustard seed oil extraction are rich in soluble polysaccharides, proteins, allyl isothiocyanates, and phenolic acids, which are known as powerful antioxidants with antimicrobial and antifungal properties. Cells were seeded at a ratio of nine (Caco-2) to one (HT29-MXT) and treated for 2 h with mustard meal extract (ME, dilution 1/50) and zinc oxide (ZnO, 50 μM) after reaching 80-100% confluence. Then, they were challenged with 5 μg/mL E. coli-LPS and incubated for another 4 h. The results show that LPS did not alter the cell viability but decreased proliferation compared to the control, ME and ZnO treatments. LPS altered the cell membrane integrity and monolayer permeability by decreasing the transepithelial electrical resistance and tight-junction protein expression. In addition, LPS increased the activity of LDH and the expression of Toll-like receptors. The mechanisms by which LPS induces these disturbances involves the overexpression of PKC, p38 MAPK, and NF-κB signaling molecules. The pretreatment with mustard meal and ZnO succeeded in counteracting the impairment of epithelial renewal, the damage of the membrane integrity and permeability as well as in restoring the gene expression of tight-junction proteins.

The Effect of Oral Care Product Ingredients on Oral Pathogenic Bacteria Transcriptomics Through RNA-Seq

Various ingredients are utilized to inhibit the growth of harmful bacteria associated with cavities, gum disease, and bad breath. However, the precise mechanisms by which these ingredients affect the oral microbiome have not been fully understood at the molecular level. To elucidate the molecular mechanisms, a high-throughput bacterial transcriptomics study was conducted, and the gene expression profiles of six common oral bacteria, including two Gram-positive bacteria (Actinomyces viscosus, Streptococcus mutans) and four Gram-negative bacteria (Porphyromonas gingivalis, Tannerella forsythia, Fusobacterium nucleatum, and Prevotella pallens), were analyzed. The bacteria were exposed to nine common ingredients in toothpaste and mouthwash at different concentrations (stannous fluoride, stannous chloride, arginine bicarbonate, cetylpyridinium chloride, sodium monofluorophosphate, sodium fluoride, potassium nitrate, zinc phosphate, and hydrogen peroxide). Across 78 ingredient-microorganism pairs with 360 treatment-control combinations, significant and reproducible ingredient-based transcriptional response profiles were observed, providing valuable insights into the effects of these ingredients on the oral microbiome at the molecular level. This research shows that oral care product ingredients applied at biologically relevant concentrations manifest differential effects on the transcriptomics of bacterial genes in a variety of oral periodontal pathogenic bacteria. Stannous fluoride, stannous chloride, and cetylpyridinium chloride showed the most robust efficacy in inhibiting the growth or gene expression of various bacteria and pathogenic pathways. Combining multiple ingredients targeting different mechanisms might be more efficient than single ingredients in complex oral microbiomes.

Dual-functional PCN-242 (Fe2Co) MOF for sensitive bacterial endotoxin detection

Endotoxin detection is paramount for monitoring bacterial contamination in food, pharmaceuticals, and clinical diagnostics. The limulus amebocyte lysate (LAL) test, which relies on horseshoe crab blood, has long been the gold standard for endotoxin detection. However, the widespread adoption of this method is constrained by ethical concerns and the high costs associated with harvesting endangered species. Although nanozyme-based colorimetric methods present a more cost-effective and straightforward alternative, their application is limited by suboptimal selectivity and sensitivity. In this study, we report the synthesis and rigorous characterization of the bimetallic PCN-242 (Fe2Co) metal-organic framework (MOF), synthesized using 2-amino terephthalic acid and a pre-synthesized [Fe2Co(μ3-O)(CH3COO)6] cluster. Steady-state kinetic analyses revealed that PCN-242 (Fe2Co) MOF exhibits a significantly higher affinity for hydrogen peroxide (H2O2) compared to horseradish peroxidase (HRP) and other iron-based MOFs. The development of a PCN-242 (Fe2Co)-based colorimetric sensor demonstrated a low limit of detection (LOD) of 1.36 μg mL-1 for endotoxins, with excellent selectivity and reproducibility, thereby enabling effective detection of bacterial endotoxins. Recognizing the potential of the PCN-242 (Fe2Co) MOF beyond endotoxin detection, we explored its utility in glucose biosensing. Moreover, incorporating glucose oxidase (GOx) into the PCN-242 (Fe2Co) MOF framework further enhanced its peroxidase-like catalytic activity. This integration enabled sensitive glucose detection, achieving LODs of 4.24 μM for glucose and 2.2 μM for H2O2 within a linear range of 1 to 150 μM. The dual functionality of PCN-242 (Fe2Co) MOF as a peroxidase mimic and biosensor platform highlights its potential for advanced catalytic and diagnostic applications, offering a versatile and ethical alternative to conventional methods.

Maternal and neonatal IgG against Klebsiella pneumoniae are associated with lower risk of neonatal sepsis: A case-control study of hospitalized neonates in Botswana

Sepsis is the leading postnatal cause of neonatal mortality worldwide. Globally Klebsiella pneumoniae is the leading cause of sepsis in hospitalized neonates. This study reports the development and evaluation of an ELISA for anti-Klebsiella IgG using dried blood spot (DBS) samples and evaluates the association of anti-Klebsiella IgG (anti-Kleb IgG) antibodies in maternal and neonatal samples with the risk of neonatal sepsis. Neonates and their mothers were enrolled at 0-96 hours of life in the neonatal unit of a tertiary referral hospital in Gaborone, Botswana and followed until death or discharge to assess for episodes of blood culture-confirmed neonatal sepsis. Neonates with sepsis had significantly lower levels of Kleb-IgG compared to neonates who did not develop sepsis (Mann-Whitney U, p = 0.012). Similarly, samples from mothers of neonates who developed sepsis tended to have less Kleb-IgG compared to mothers of controls. The inverse correlation between Kleb-IgG levels and all-cause bacteremia suggests that maternal Kleb-IgG may be protective through cross-reactivity with common bacterial epitopes. These data support the continued use of immunoglobulin assays using DBS samples to explore the role of passive immunity on neonatal sepsis risk and reaffirm the critical need for research supporting the development of maternal vaccines for neonatal sepsis.

Yielding behaviour of chemically treated Pseudomonas fluorescens biofilms

The mechanics of biofilms are intrinsically shaped by their physicochemical environment. By understanding the influence of the extracellular matrix composition, pH and elevated levels of cationic species on the biofilm rheology, novel living materials with tuned properties can be formulated. In this study, we examine the role of a chaotropic agent (urea), two divalent cations and distilled deionized water on the nonlinear viscoelasticity of a model biofilm Pseudomonas fluorescens. The structural breakdown of each biofilm is quantified using tools of non-linear rheology. Our findings reveal that urea induced a softening response, and displayed strain overshoots comparable to distilled deionized water, without altering the microstructural packing fraction and macroscale morphology. The absorption of divalent ferrous and calcium cations into the biofilm matrix resulted in stiffening and a reduction in normalized elastic energy dissipation, accompanied by macroscale morphological wrinkling and moderate increases in the packing fraction. Notably, ferrous ions induced a predominance of rate dependent yielding, whereas the calcium ions resulted in equal contribution from both rate and strain dependent yielding and structural breakdown of the biofilms. Together, these results indicate that strain rate increasingly becomes an important factor controlling biofilm fluidity with cation-induced biofilm stiffening. The finding can help inform effective biofilm removal protocols and in development of bio-inks for additive manufacturing of biofilm derived materials.

Botulinum toxin A dampened inflammatory response in BV-2 microglial cells

Our previous studies have demonstrated the analgesic effects of botulinum toxin type A (BoNT/A) in a pre-clinical model of rheumatoid arthritis of the temporomandibular joint, where we proposed that BoNT/A decreases the neurogenic milieu after reaching the subnucleus caudalis. However, it is unknown whether BoNT/A directly regulates microglial cell activity. Therefore, the present study investigates the effects of BoNT/A on a microglial murine cell lineage (BV-2) in different inflammatory conditions. Cellular viability and proliferation were carried out with different concentrations of BoNT/A (ranging from 0.3125 to 20 U/mL) for 24 h. Cells were primed with carrageenan (300 μg/mL) or Lipopolysaccharides (LPS) (20 ng/mL). The gene expression of IL-1β, IL-6, IL-18, TNF-α, Ikkβ, p65, Iba1 were quantified using PCR-RT. The supernatant was used to determine IL-1β, IL-6, and TNF-α levels. For all data, the significance level was set at 5%. Overall, data analysis revealed that BoNT/A 1.25 U/mL exhibited the greatest effect cell viability and proliferation. In addition, genes associated with inflammatory response in both stimuli (carrageenan and LPS) were downregulated in the presence of BoNT/A. Lastly, BoNT/A mitigates the protein levels of IL-1β and TNF-α in a time and dose-dependent manner. In conclusion, our results revealed that BoNT/A directly modulates the microglial cells' activities in an inflammatory context, opening new perspectives for using BoNT/A, considering its potential immunomodulatory effect.

Lessons learned from contamination with endotoxin originated from the supplement in the cell culture medium

Introduction

Endotoxin is a typical pyrogen derived from the outer membrane of Gram-negative bacteria. In fabricating cell-based medicinal products, it is necessary to control endotoxin in the process and the products. In the quality control tests of our clinical study, endotoxin concentration in the culture supernatant of autologous oral mucosal epithelial cell sheets exceeded the criterion value. Therefore, endotoxin measurements were conducted to clarify the cause of the endotoxin contamination.

Methods

The reagents used to prepare the culture medium, the unused culture medium, and the culture supernatants were diluted with pure water. Endotoxin concentrations in the diluted samples were measured.

Results

Endotoxin was detected in both the unused culture medium and the culture supernatant of the epithelial cell sheets at higher concentrations than the criterion value. Therefore, endotoxin concentrations in the reagents used to prepare the culture medium were measured and were found to be below the criterion value, except for cholera toxin. On the other hand, three lots of cholera toxin products were used for the measurement, and the endotoxin concentrations were higher than the criterion value. The results indicate that the endotoxin contamination is caused by the cholera toxin product.

Conclusions

To prevent endotoxin contamination in cell-based medicinal products, endotoxin concentrations in reagents used for the fabrication should be measured in the facility conducting clinical research or confirmed by an adequate certificate of analysis from the manufacturers of the reagents.

Fighting the enemy within: Systemic immune defense against mucosal Salmonella infection

Salmonella infection remains a persistent global health threat, as different serovars induce a range of clinical disease, depending upon bacterial virulence and host susceptibility. While some Salmonella serovars induce gastroenteritis in healthy individuals, others can cause more serious systemic enteric fever or invasive nontyphoidal Salmonellosis. The rise of antibiotic resistance, coupled with the absence of effective vaccines for most serovars, perpetuates the spread of Salmonella in endemic regions. A detailed mechanistic understanding of immunity to Salmonella infections has been aided by the availability of mouse models that have served as a valuable tool for understanding host-pathogen interactions under controlled laboratory conditions. These mouse studies have delineated the processes by which early inflammation is triggered after infection, how adaptive immunity is initiated in lymphoid tissues, and the contribution of lymphocyte memory responses to resistance. While recent progress has been made in vaccine development for some causes of enteric fever, deeper understanding of Salmonella-specific immune memory might allow the formation of new vaccines for all serovars. This review will provide a summary of our understanding of vaccination and protective immunity to Salmonella with a focus on recent developments in T cell memory formation.

Colistin Resistance Mechanism and Management Strategies of Colistin-Resistant Acinetobacter baumannii Infections

The emergence of antibiotic-resistant Acinetobacter baumannii (A. baumannii) is a pressing threat in clinical settings. Colistin is currently a widely used treatment for multidrug-resistant A. baumannii, serving as the last line of defense. However, reports of colistin-resistant strains of A. baumannii have emerged, underscoring the urgent need to develop alternative medications to combat these serious pathogens. To resist colistin, A. baumannii has developed several mechanisms. These include the loss of outer membrane lipopolysaccharides (LPSs) due to mutation of LPS biosynthetic genes, modification of lipid A (a constituent of LPSs) structure through the addition of phosphoethanolamine (PEtN) moieties to the lipid A component by overexpression of chromosomal pmrCAB operon genes and eptA gene, or acquisition of plasmid-encoded mcr genes through horizontal gene transfer. Other resistance mechanisms involve alterations of outer membrane permeability through porins, the expulsion of colistin by efflux pumps, and heteroresistance. In response to the rising threat of colistin-resistant A. baumannii, researchers have developed various treatment strategies, including antibiotic combination therapy, adjuvants to potentiate antibiotic activity, repurposing existing drugs, antimicrobial peptides, nanotechnology, photodynamic therapy, CRISPR/Cas, and phage therapy. While many of these strategies have shown promise in vitro and in vivo, further clinical trials are necessary to ensure their efficacy and widen their clinical applications. Ongoing research is essential for identifying the most effective therapeutic strategies to manage colistin-resistant A. baumannii. This review explores the genetic mechanisms underlying colistin resistance and assesses potential treatment options for this challenging pathogen.

The role of the essential GTPase ObgE in regulating lipopolysaccharide synthesis in Escherichia coli

During growth, cells need to synthesize and expand their envelope, a process that requires careful regulation. Here, we show that the GTPase ObgE of E. coli contributes to the regulation of lipopolysaccharide (LPS) synthesis, an essential component of the Gram-negative outer membrane. Using a dominant-negative mutant (named 'ObgE*'), we show a direct interaction between ObgE and LpxA, which catalyzes the first step in LPS synthesis. This interaction is enhanced by the mutation in ObgE* which, when bound to GTP, leads to inhibition of LpxA, decreased LPS synthesis, and cell death. Although wild-type ObgE does not exert the same strong effects as ObgE* on LpxA or LPS synthesis, our data indicate that ObgE participates in the regulation of cell envelope synthesis in E. coli. Because ObgE also influences other cellular functions (i.e., ribosome assembly, DNA replication, etc.), it seems increasingly plausible that this GTPase coordinates several processes to finetune cell growth.

Glycomolecules: from "sweet immunity" to "sweet biostimulation"?

Climate changes and environmental contaminants are daunting challenges that require an urgent change from current agricultural practices to sustainable agriculture. Biostimulants are natural solutions that adhere to the principles of organic farming and are believed to have low impacts on the environment and human health. Further, they may contribute to reducing the use of chemical inputs while maintaining productivity in adverse environments. Biostimulants are generally defined as formulated substances and microorganisms showing benefits for plant growth, yield, rhizosphere function, nutrient-use efficiency, quality of harvested products, or abiotic stress tolerance. These biosolutions are categorized in different subclasses. Several of them are enriched in glycomolecules and their oligomers. However, very few studies have considered them as active molecules in biostimulation and as a subclass on their own. Herein, we describe the structure and the functions of complex polysaccharides, glycoproteins, and glycolipids in relation to plant defense or biostimulation. We also discuss the parallels between sugar-enhanced plant defense and biostimulation with glycomolecules and introduce the concept of sweet biostimulation or glycostimulation.

Non-antibiotic compounds associated with humans and the environment can promote horizontal transfer of antimicrobial resistance genes

Horizontal gene transfer plays a key role in the global dissemination of antimicrobial resistance (AMR). AMR genes are often carried on self-transmissible plasmids, which are shared amongst bacteria primarily by conjugation. Antibiotic use has been a well-established driver of the emergence and spread of AMR. However, the impact of commonly used non-antibiotic compounds and environmental pollutants on AMR spread has been largely overlooked. Recent studies found common prescription and over-the-counter drugs, artificial sweeteners, food preservatives, and environmental pollutants, can increase the conjugative transfer of AMR plasmids. The potential mechanisms by which these compounds promote plasmid transmission include increased membrane permeability, upregulation of plasmid transfer genes, formation of reactive oxygen species, and SOS response gene induction. Many questions remain around the impact of most non-antibiotic compounds on AMR plasmid conjugation in clinical isolates and the long-term impact on AMR dissemination. By elucidating the role of routinely used pharmaceuticals, food additives, and pollutants in the dissemination of AMR, action can be taken to mitigate their impact by closely monitoring use and disposal. This review will discuss recent progress on understanding the influence of non-antibiotic compounds on plasmid transmission, the mechanisms by which they promote transfer, and the level of risk they pose.

Microbiota-gut-brain axis: Natural antidepressants molecular mechanism

BACKGROUND

Major depressive disorder (MDD) is a severe mental health condition characterized by persistent depression, impaired cognition, and reduced activity. Increasing evidence suggests that gut microbiota (GM) imbalance is closely linked to the emergence and advancement of MDD, highlighting the potential significance of regulating the "Microbiota-Gut-Brain" (MGB) axis to impact the development of MDD. Natural products (NPs), characterized by broad biological activities, low toxicity, and multi-target characteristics, offer unique advantages in antidepressant treatment by regulating MGB axis.

PURPOSE

This review was aimed to explore the intricate relationship between the GM and the brain, as well as host responses, and investigated the mechanisms underlying the MGB axis in MDD development. It also explored the pharmacological mechanisms by which NPs modulate MGB axis to exert antidepressant effects and addressed current research limitations. Additionally, it proposed new strategies for future preclinical and clinical applications in the MDD domain.

METHODS

To study the effects and mechanism by which NPs exert antidepressant effects through mediating the MGB axis, data were collected from Web of Science, PubMed, ScienceDirect from initial establishment to March 2024. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as flavonoids,alkaloids,polysaccharides,saponins, terpenoids, can treat MDD by regulating the MGB axis. Its mechanism includes balancing GM, regulating metabolites and neurotransmitters such as SCAFs, 5-HT, BDNF, inhibiting neuroinflammation, improving neural plasticity, and increasing neurogenesis.

CONCLUSIONS

NPs display good antidepressant effects, and have potential value for clinical application in the prevention and treatment of MDD by regulating the MGB axis. However, in-depth study of the mechanisms by which antidepressant medications affect MGB axis will also require considerable effort in clinical and preclinical research, which is essential for the development of effective antidepressant treatments.

The implication of dendritic cells in lung diseases: Immunological role of toll-like receptor 4

The immune responses play a profound role in the progression of lung lesions in both infectious and non-infectious diseases. Dendritic cells, as the "frontline" immune cells responsible for antigen presentation, set up a bridge between innate and adaptive immunity in the course of these diseases. Among the receptors equipped in dendritic cells, Toll-like receptors are a group of specialized receptors as one type of pattern recognition receptors, capable of sensing environmental signals including invading pathogens and self-antigens. Toll-like receptor 4, a pivotal member of the Toll-like receptor family, was formerly recognized as a receptor sensitive to the outer membrane component lipopolysaccharide derived from Gram-negative bacteria, triggering the subsequent response. Moreover, its other essential roles in immune responses have drawn significant attention in the past decade. A better understanding of the implication of Toll-like receptor 4 in dendritic cells could contribute to the management of pulmonary diseases including pneumonia, pulmonary tuberculosis, asthma, acute lung injury, and lung cancer.

Therapeutic Interventions for Pseudomonas Infections in Cystic Fibrosis Patients: A Review of Phase IV Trials

Pseudomonas aeruginosa (Pa) poses a significant threat to individuals with cystic fibrosis (CF), as this bacterium is highly adaptable and resistant to antibiotics. While early-stage Pa infections can often be eradicated with aggressive antibiotic therapy, chronic infections are nearly impossible to eliminate and require treatments that focus on long-term bacterial suppression. Without such suppression, these persistent infections can severely damage the lungs, leading to serious complications and a reduced life expectancy for CF patients. Evidence for a specific treatment regimen for managing Pa infections in CF patients remains limited. This narrative review provides a detailed analysis of antimicrobial therapies assessed in completed phase IV trials, focusing on their safety and efficacy, especially with prolonged use. Key antibiotics, including tobramycin, colistin, meropenem, aztreonam, ceftolozane/tazobactam, ciprofloxacin, and azithromycin, are discussed, emphasizing their use, side effects, and delivery methods. Inhaled antibiotics are preferred for their targeted action and minimal side effects, while systemic antibiotics offer potency but carry risks like nephrotoxicity. The review also explores emerging treatments, such as phage therapy and antibiofilm agents, which show promise in managing chronic infections. Nonetheless, further research is necessary to enhance the safety and effectiveness of existing therapies while investigating new approaches for better long-term outcomes.