BACKGROUND:Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction secondary to sepsis; however, its pathogenesis remains poorly defined. This study characterizes gut-microbiota-brain axis dysbiosis and aberrant tryptophan metabolism in SAE, providing a multi-dimensional framework to understand the underlying pathways. METHODS:SAE was induced in rats via cecal ligation and puncture, with Sham and fecal microbiota transplantation (FMT) groups as controls. Cognitive and emotional functions were assessed using the open field and novel object recognition tests. Gut microbiota and metabolite profiles were analyzed through 16S rDNA sequencing and untargeted metabolomics. Hippocampal neuroinflammation and neuronal apoptosis were quantified via ELISA, TUNEL staining, Western blot, and flow cytometry. In vitro CD4+ T cell cultures and AhR inhibitor (CH-223191) interventions were performed to verify the mechanism of tryptophan metabolite-mediated immune regulation via the AhR pathway. RESULTS:SAE rats exhibited cognitive deficits, anxiety- and depression-like behaviors, hippocampal neuronal injury, and elevated pro-inflammatory cytokines (IL-17A, IL-1β, TNF-α), alongside gut dysbiosis and disrupted tryptophan metabolism. FMT effectively restructured gut microbiota, partially reversed metabolic abnormalities, alleviated neurobehavioral deficits, and attenuated neuroinflammation. In vitro analyses demonstrated that SAE-associated microbial metabolites upregulated AhR expression, inducing a Th17/Treg imbalance. Inhibiton of AhR signaling (via CH-223191-mediated blockade of aberrant signaling) mitigated neuronal injury, an effect reversed by exogenous IL-1β. CONCLUSION:This study delineates a gut-brain axis mechanism in which sepsis-induced dysbiosis perturbs tryptophan metabolism and AhR signaling, driving a Th17/Treg imbalance that mediates IL-17A/IL-1β-driven hippocampal injury. These findings validate FMT and AhR modulation as potential therapeutic strategies for SAE.
Scuticociliatosis, caused by the parasitic ciliate Philasterides dicentrarchi, is one of the most important infectious diseases affecting turbot (Scophthalmus maximus) aquaculture. Despite the critical role of parasite surface antigens in host-parasite interactions, their molecular diversity and expression dynamics remain poorly understood. Here, we applied an integrated multi-omics approach combining genome mining, transcriptomics, structural annotation, phylogenetic analysis, proteomics and immunological assays to identify and characterize a repertoire of putative variant surface protein-like (VSP-like) antigens in P. dicentrarchi. Throughout this study, the term VSP-like is used as a descriptive designation for cysteine-rich surface proteins sharing structural characteristics with both Giardia variant-specific surface proteins (VSPs) and ciliate immobilization antigens (i-antigens), without implying functional or evolutionary equivalence with either protein family. Genome and transcriptome analyses identified a diverse repertoire of cysteine-rich surface proteins displaying predicted N-terminal signal peptides, cysteine-rich extracellular domains and C-terminal membrane-associated regions compatible with glycosylphosphatidylinositol (GPI) anchoring. Phylogenetic reconstruction resolved these proteins into several distinct clades, whereas LC-MS/MS analysis confirmed the expression of multiple VSP-like families in trophozoites. Integration of structural, phylogenetic and proteomic data with B-cell epitope prediction enabled the rational prioritization of putative candidate vaccine antigens for future experimental evaluation. Comparative analyses further revealed dynamic modulation of the VSP-like-associated antigenic profile during successive parasite passages. RT-qPCR demonstrated differential VSP2 transcript abundance between early and late infective passages, whereas ELISA and two-dimensional immunoblot analyses revealed marked differences in anti-rVSP2 antigen recognition among parasite populations. Moreover, sequencing of cloned transcripts and exposure of trophozoites to immune turbot serum revealed shifts in the expressed antigenic repertoire, suggesting that host immune factors may contribute to modulation of VSP-like expression. Together, these findings provide the first comprehensive molecular characterization of a repertoire of putative VSP-like surface antigens in P. dicentrarchi. They reveal a dynamic antigenic repertoire associated with parasite adaptation and host immune interactions, establish a framework for investigating antigenic variation in parasitic scuticociliates, and provide a rational basis for the future experimental evaluation of vaccine antigens against scuticociliatosis.
With the rapid expansion of the meat goat farming industry in China and intensified interregional movement of goats, respiratory diseases have become increasingly prevalent across domestic goat farms-particularly under suboptimal husbandry conditions-posing a significant challenge to effective disease prevention and control. Mannheimia haemolytica, a primary bacterial pathogen implicated in caprine respiratory disease, exhibits marked geographic variation in key phenotypic and genotypic traits, including serotype distribution and antimicrobial resistance profiles. To address this critical animal health concern, Mannheimia haemolytica was isolated from clinical specimens collected from multiple commercial goat farms in Jingmen City, Hubei Province, and performed an integrated phenotypic and genomic characterization, including Gram staining, biochemical identification, molecular biological identification, virulence gene identification, genetic and evolutionary analysis, antimicrobial susceptibility testing, pathogenicity assays, whole-genome sequencing, and qPCR detection. Our analysis identified a Mannheimia haemolytica strain belonging to serotype A2. Whole-genome analysis confirmed the presence of six core virulence-associated genes: LKT-C, gs60, fbpA, SodA, gapA, and dnaA. The isolated strain displayed a defined antimicrobial resistance profile and induced significant dysregulation of pro-inflammatory cytokine expression in infected murine lung tissue, thereby revealing mechanistic insights into its pathogenicity. Collectively, this study delivers a rigorously characterized reference isolate of caprine-derived Mannheimia haemolytica serotype A2, advances knowledge of its genomic landscape, virulence repertoire, and host-pathogen interplay, and provides a foundational evidence base to inform targeted, science-driven interventions against respiratory disease in goat production.
BACKGROUND:Moraxella catarrhalis is a Gram-negative opportunistic pathogen of the human respiratory tract, historically considered a commensal but now established as a leading cause of otitis media in children and acute exacerbations of chronic obstructive pulmonary disease (COPD) in adults. While phylogenomic studies have revealed two deeply divergent evolutionary lineages, Sero resistant (SR) and Sero sensitive (SS), with distinct virulence and resistance profiles, the molecular dialogue between this bacterium and its host remains incompletely understood. OBJECTIVE:This review moves beyond traditional virulence factor enumeration to explore emerging frontiers in host-pathogen interaction at the RNA and epigenetic levels. We critically synthesize recent advances in three areas: (i) potential manipulation of host microRNA networks by M. catarrhalis and its extracellular vesicles, (ii) the hypothesized role of bacterial small RNAs in interkingdom communication and immune modulation, and (iii) epigenetic regulatory mechanisms, including phasevarions and DNA methylation, that govern phenotypic heterogeneity and vaccine evasion. PROPOSED FRAMEWORK:We propose a mechanistic model wherein M. catarrhalis may actively reprogram host gene expression post-transcriptionally and exploit epigenetic phase-variation to evade immunity. However, we emphasize that much of this model remains hypothetical; direct experimental evidence in M. catarrhalis is currently limited. By integrating findings from transcriptomic profiling, extracellular vesicle biology, and epigenetics, we provide a contemporary framework that reframes M. catarrhalis not as a passive opportunist but as a potential active manipulator of host cellular machinery, a hypothesis that requires rigorous testing. We identify critical knowledge gaps, propose mechanistic models for miRNA-mediated pathogenesis, and outline priority areas for therapeutic and preventive intervention.
BACKGROUND:Pseudomonas aeruginosa (P. aeruginosa) is a common opportunistic pathogen responsible for skin infections. Tannic acid, a representative hydrolysable tannin, has broad-spectrum antibacterial properties and potential applications in wound healing. OBJECTIVE:To characterize the concentration-dependent antibacterial and anti-virulence effects of TA against P. aeruginosa, identify associated transcriptional responses, and evaluate its therapeutic potential in an infected wound model. RESULTS:High concentrations of tannic acid disrupted the integrity of the P. aeruginosa cell membrane, leading to leakage of intracellular components, and were associated with marked alterations in bacterial protein profiles. At sub-inhibitory concentrations (sub-MICs), tannic acid significantly attenuated bacterial virulence by suppressing pyocyanin and rhamnolipid biosynthesis, biofilm formation, proteinase activity, and bacterial motility. TA treatment at 64 μg/mL was associated with transcriptional changes in genes involved in biofilm formation and efflux functions. In a rat wound model infected with P. aeruginosa, tannic acid treatment significantly decreased bacterial burden, attenuated histopathological injury, contained infection progression, and expedited wound closure. CONCLUSION:This study evaluated the antibacterial and anti-virulence effects of tannic acid against P. aeruginosa, characterized associated transcriptional responses using RNA sequencing, and assessed its therapeutic potential in an infected wound model.
Silymarin is a flavonolignan complex traditionally used for hepatoprotection, but its interactions with the gastrointestinal microbiota of ruminants remain poorly characterized. This study evaluated the effects of dietary silymarin on ruminal and intestinal microbiota in lactating Jersey cows. Twelve cows were assigned to a crossover design and received either a control diet or the same diet fed with silymarin (5 g/cow/day). Rumen fluid and fecal samples were collected on day 28 of the first experimental period and analyzed by 16S rRNA gene sequencing, alongside ruminal protozoa enumeration. Silymarin intake did not alter alpha or beta diversity of either ruminal or intestinal microbiota. However, differential abundance analyses revealed selective modulation of specific microbial taxa in both compartments. In the rumen, silymarin reduced the relative abundance of taxa previously associated with denitrification and redox processes, while increasing taxa previously associated with diverse nitrogen metabolic capabilities. These changes were accompanied by a significant reduction in ruminal protozoa counts and an enrichment of predicted functional pathways related to nitrogen metabolism, which may be related to the differences in ruminal fermentation. In the intestinal microbiota, silymarin promoted selective taxonomic shifts without disrupting community structure and was associated with enrichment of predicted functional pathways related to NOD-like receptor signaling, indicating differences in the predicted functional potential of the gut microbiota that may be associated with microbiota-host interactions. Overall, silymarin intake selectively modulated the gastrointestinal microbiota without altering its overall community structure, as indicated by the absence of significant changes in alpha and beta diversity, and was associated with changes in predicted functional pathways. Together, these findings are consistent with the hypothesis that silymarin supplementation was associated with selective modulation of the gastrointestinal microbiota and its predicted functional potential, which may be associated with the fermentative and metabolic responses.
Zaire Ebola virus (EBOV) is one of the main pathogens causing Ebola hemorrhagic fever. The whole human monoclonal antibody Mab114, which can specifically recognize EBOV, has good functions of neutralizing the virus and improving the survival rate of infected animals. The longer in vivo half-life of antibody drugs is mainly achieved through pH dependent binding of the receptor FcRn. This study used computer simulation methods to construct the spatial conformation of human Fc and human FcRn complexes based on molecular docking and mechanical optimization. The key structural domains and important amino acid sites for the binding of human Fc and human FcRn were determined. Based on this, two Fc mutants were designed, and two Fc mutant antibodies Mab114-M5 and Mab114-M6 were constructed using whole human monoclonal antibody Mab114 as the model antibody. The affinity, in vivo and in vitro neutralization function, in vivo serum metabolism of human FcRn transgenic mice, and in vivo antiviral activity were verified through experiments. The results showed that the mutant antibody had a significantly longer retention time in mice compared to Mab114, and also exhibited similar activity in neutralizing EBOV as the maternal antibody Mab114. Fc mutants have the potential to have a long half-life in vivo, thereby reducing medication frequency and providing new ideas for the development of long-acting antibody therapy drugs.
This study reports, for the first time, the nematicidal potential of the cell-free culture filtrate of Planococcus plakortidis against the citrus nematode Tylenchulus semipenetrans. In vitro bioassays revealed a strong nematicidal activity, reaching 83.06% mortality after five days of incubation. The highest nematicidal effect coincided with the maximum bacterial population density (5.6 × 106 cells ml-1), suggesting a close association between the exponential growth phase of the bacterium and the production of bioactive metabolites. Under greenhouse conditions, application of the culture filtrate through irrigation significantly reduced nematode populations and enhanced the growth performance of Citrus aurantium and Citrange Carrizo plants infested with T. semipenetrans. These findings highlight the potential of P. plakortidis-derived metabolites as an environmentally friendly and sustainable biological alternative for the management of citrus plant-parasitic nematodes.
Bacterial biofilms constitute a critical challenge to public health worldwide. The prevalence of antibiotic-resistant Gram-negative bacteria implicated in biofilm formation has increased globally, especially among pathogens connected to healthcare facilities. Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen, known for its antibiotic-resistant strains that cause healthcare-associated infections (HAIs). The clinical strains of A. baumannii can develop biofilms on various biotic and abiotic surfaces, enhancing colonization of medical devices, thereby contributing to healthcare-associated infections. However, the lack of effective treatment options raises significant concerns regarding human infections caused by A. baumannii strains. The limited availability of effective antibiotics has encouraged the development of alternative antimicrobial approaches, such as using bacterial metabolites. Here, a Shigella flexneri strain was isolated from the human gastrointestinal tract and its crude extracellular metabolite was extracted. The antibiofilm efficacy of Shigella flexneri-derived crude extracellular metabolite (SFEM) was evaluated by using the crystal violet assay and fluorescence imaging. Substantial growth inhibition was observed at 100 μg/mL, while the minimum bactericidal concentration (MBC) was determined as 100 μg/mL. The MTT assay for cytotoxicity on Jurkat cells showed that SFEM did not significantly lower cell viability across the range of concentrations tested. The study demonstrates the potential of bacterial metabolites as antibiofilm agents against A. baumannii biofilms and supports further investigation of their bioactive properties. The overall experimental workflow of the present study is illustrated in the graphical abstract.
This study documents the first disease outbreak associated with Thaparocleidus caecus infection in Pangasius nasutus, representing a new host record for the parasite in Malaysia. In January 2025, an investigation was initiated following persistent mortality among the broodstock of P. nasutus. The affected fish exhibited clinical signs including respiratory distress, refusal to feed, erratic swimming behaviour, flashing, and scraping against the tank bottom. Gill inspection revealed operculum erosion, pale gill colouration, and signs of gill hyperplasia. Histopathological examination of the gills revealed severe epithelial hyperplasia of the secondary lamellae, lamellar necrosis, aneurysms of the capillary vessels, epithelial lifting (intraepithelial oedema), and massive leucocyte infiltration. Wet-mount examination identified the monogenean as T. caecus based on its sclerite morphology and morphometric assessment. PCR amplification and sequencing of the 28S rRNA gene further supported the species identification, with the obtained sequence forming a monophyletic clade with the reference sequences. The outbreak resulted in a cumulative mortality rate of 52% among the broodstock, with estimated losses of USD 1300. These findings highlight that Thaparocleidus infection poses a significant threat to P. nasutus aquaculture and conservation, especially during hatchery operations.
Mastitis is one of the most severe diseases in dairy cows worldwide, causing substantial economic losses to the dairy industry. However, effective prevention and control strategies, remain to be further elucidated. This study aims to investigate the protective effects of Lactobacillus reuteri (L. reuteri) and its extracellular vesicles (EVs) against S. aureus-induced mastitis and to explore the potential molecular mechanisms. We established a murine mastitis model induced by S. aureus, followed by treatment with extracellular vesicles secreted by L. reuteri. Histopathological alterations in mammary tissues were assessed using hematoxylin and eosin (HE) staining. Enzyme-linked immunosorbent assay (ELISA) was performed to quantify the concentrations of pro-inflammatory cytokines. Western blotting was utilized to characterize the expression levels of key proteins involved in the NF-κB signaling cascade. We demonstrate that L. reuteri effectively ameliorates S. aureus-induced mastitis in mice, accompanied by inhibited inflammatory responses and restored integrity of the blood-milk barrier in mammary tissues. Further studies revealed that EVs derived from L. reuteri exert similar protective effects, significantly alleviating pathological injury in mammary tissues. Mechanistically, S. aureus infection was associated with upregulation of NF-κB/NLRP3 signaling components and increased TLR2 expression in mammary tissues, whereas L. reuteri-derived EVs markedly suppressed this inflammatory cascade in parallel with reduced TLR2 expression, attenuating inflammatory cytokine release and maintaining blood-milk barrier integrity Collectively, our findings indicate that L. reuteri-derived EVs effectively alleviate S. aureus-induced mastitis in association with suppression of the NF-κB/NLRP3 inflammatory cascade and restoration of mammary barrier integrity. This study highlights the protective role of probiotics and their derived EVs against mastitis pathogenesis, providing promising preventive and therapeutic strategies as well as candidate biomaterials for the management of this disease.
BACKGROUND:Legionnaires' disease (LD) primarily presents with fever and pneumonia. Legionella pneumophila (L. pneumophila), a facultative intracellular pathogen capable of forming structured biofilms, poses two well-recognized clinical challenges for LD treatment: antibiotic resistance and the difficulty of eradicating persistent intracellular infections. Ferroptosis, an iron-dependent regulated cell death modality, is implicated in the pathogenesis of diverse bacterial infections, but its specific regulatory mechanism in L. pneumophila infection remains largely uncharacterized. This study aims to identify key ferroptosis-related genes during L. pneumophila infection via bioinformatics analysis and molecular biological validation, to provide theoretical support for subsequent research. METHODS:Transcriptomic datasets of L. pneumophila infection models were retrieved from the Gene Expression Omnibus. Differentially expressed genes were screened, intersected with curated Ferroptosis Database, and validated in independent mouse infection cohorts. Candidate genes were characterized via protein-protein interaction network analysis, functional enrichment analysis, immune infiltration correlation analysis, and quantitative real-time polymerase chain reaction validation. RESULTS:A total of 23 ferroptosis-associated shared differentially expressed genes were identified, with 7 core candidates (Cav1, Hif1α, Hspa1b, Stat3, CD44, Cxcl10, Ptgs2) showing consistent statistically significant differential expression across validation cohorts and experimental assays. These core genes act via independent regulatory pathways, suggesting ferroptosis is triggered by multiple mechanisms during infection, and mediate activation of multiple immune cell subsets. CONCLUSIONS:This study confirms ferroptosis plays a critical role in Legionnaires' disease pathogenesis, and the 7 core genes provide novel insights into the molecular mechanisms of the disease.
Fig (Ficus carica L.) canker is an important disease affecting the productivity and longevity of fig orchards. During surveys of symptomatic orchards in northern Iran, Diaporthe sp. isolates were consistently recovered from trunk and branch cankers associated with extensive vascular discoloration and wood necrosis. This study characterized these isolates using morphological, physiological, and molecular identification. Their pathogenicity, aggressiveness, and interactions with different fig genotypes were also evaluated. Based on cultural and microscopic features, the isolates were separated into two distinct morphotypes. Phylogenetic analyses of translation elongation factor 1-α (tef1) and β-tubulin (tub2) sequences placed the isolates within the broadly circumscribed D. arecae complex, with tef1 data indicating two subclades corresponding to Morphotypes A and B. The two morphotypes differed in colony characteristics, growth responses, conidial morphology, and phylogenetic placement. Pathogenicity assays on one-year-old fig saplings and detached leaves demonstrated that all isolates were pathogenic, with symptom reproduction and morphological re-isolation of colonies consistent with the inoculated isolates. Significant differences in aggressiveness were detected among isolates. Comparative inoculations on six fig genotypes revealed significant isolate × genotype interactions across all evaluated disease traits. 'Gilasi' and 'Payves' were the most susceptible genotypes, whereas 'Matti' and 'Sabz' consistently exhibited reduced lesion development and lower pycnidial production. Extensive internal vascular necrosis frequently exceeded visible external symptoms, whether this reflects latent fungal colonization remains a hypothesis that was not directly tested in this study. This study provides a preliminary characterization of D. arecae isolates associated with fig canker from a single locality and indicates that morphological, phylogenetic, and pathogenic variation can occur within a broadly circumscribed species. The results contribute to our understanding of D. arecae associated with fig canker and provide a basis for future investigations of diversity, pathogenicity, and host responses within this species.
Echinococcosis, caused by the larval stage of the tapeworm Echinococcus species, threatens global public health and livestock economics. Currently, quantitative reverse transcription polymerase chain reaction (RT-qPCR) is essential for mRNA quantification, and its accuracy relies on stably expressed reference genes that must be validated under specific experimental conditions. In this study, we systematically evaluated the expression stability of twelve candidate reference genes in the liver, lung, and spleen of E. multilocularis-infected and healthy controls (n = 6 per group). Based on raw cycle threshold (Ct) values generated by RT-qPCR, the stability of each candidate gene was evaluated using both unstratified (samples from the same tissue were treated as a single cohort) and stratified (samples grouped by experimental condition) strategies. Then multiple algorithms including NormFinder, geNorm, BestKeeper, and Delta-Ct were employed to generate a comprehensive stability ranking of candidate genes. The validated optimal reference gene combinations were subsequently used to normalize gene expression via the comparative Ct (2-ΔΔCt) method. Our findings demonstrated that optimal reference genes were tissue-specific under E. multilocularis infection. For example, stratified analysis identified Actb as the most stable in both the liver (stability value = 0.16) and lung (stability value = 0.29), and Rpl13a (stability value = 0.10) in the spleen. Consequently, distinct reference gene combinations were validated and recommended respectively for liver, lung, and spleen, providing a reliable basis for accurate gene expression analysis by RT-qPCR. The reference sets will facilitate future investigations into echinococcosis, including disease pathogenesis, antiparasitic drug efficacy assessment, and therapeutic target discovery.
Toxoplasma gondii is an intracellular parasite that causes toxoplasmosis, which can have significant health impacts, particularly in immunocompromised individuals. The total extract from T. gondii contains multiple antigens that are promising vaccine candidates. Thus, the present research aimed to optimise PLGA nanoparticles loaded with total T. gondii tachyzoite antigen through an empirical, stepwise approach. The nanocarriers were designed to target the nasal mucosa and trigger an effective and protective immune response against T. gondii infection. The optimized formulation exhibited favourable physicochemical properties, including an appropriate particle size and low polydispersity, which ensured efficient dendritic cell uptake. Notably, the optimized nanocarriers permeated human nasal epithelial cells, were internalized, and upregulated MHC class II expression in bone marrow-derived dendritic cells. These findings highlight the potential of the formulated PLGA nanoparticles as a promising platform for intranasal vaccines, activating dendritic cells and thus initiating an immune response against T. gondii.
BACKGROUND:Chromoblastomycosis (CBM) is a chronic subcutaneous infection caused by the dematiaceous fungi. The chronic persistence of CBM brings great distress to patients. Myeloid-derived suppressor cells (MDSCs) are implicated in immunosuppression during chronic infections, yet the role of MDSCs in CBM remains elusive. OBJECTIVES:This study aimed to investigate how Fonsecaea monophora (F. monophora) reprograms polymorphonuclear myeloid-Derived suppressor cells (PMN-MDSCs) to suppress T-cell immunity. METHODS:We detected CD11b + CD15+ PMN-MDSCs in CBM patient lesions via immunofluorescence. Using the HL60 cell model, we examined the induction of PMN-MDSCs by F. monophora conidia and assessed the immunosuppressive function through T-cell proliferation assay (EdU assay) and Annexin V/PI apoptosis staining. Underlying mechanisms were probed through RNA-sequencing, analysis of autophagic flux (LC3B, p62), and measurement of reactive oxygen species. Interventions involved the autophagy activator rapamycin and the ROS scavenger N-acetylcysteine. RESULTS:PMN-MDSCs were significantly enriched in CBM lesions compared to healthy and acute infection controls. F. monophora conidia effectively induced the differentiation of functional PMN-MDSCs in vitro, which suppressed T-cell proliferation and viability. In conidia-induced PMN-MDSCs, transcriptomic and functional analyses revealed that immunosuppression is mediated through impaired autophagic flux and subsequent ROS accumulation, rather than the classical ARG1/NOS2 pathways. Crucially, the immunosuppressive effects were reversed by interventions targeting autophagy or ROS. CONCLUSION:F. monophora drives PMN-MDSCs-mediated immunosuppression through an autophagy impairment-ROS accumulation axis, providing a mechanistic basis for CBM chronicity and a therapeutic strategy targeting MDSCs.
Cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae increasingly limit therapeutic options, necessitating novel antimicrobial strategies. This study investigated the antibacterial and immunomodulatory potential of a bioactive Streptomyces isolate (SGM-12) and its silver nanoparticle (AgNP) formulations using integrated experimental and computational approaches. In silico docking and ADME profiling predicted metabolite-target interactions, while molecular dynamics simulations evaluated AgNP-bacterial membrane interactions. The isolate was cultured, extracted, and fractionated into six fractions (F1-F6), and tested against resistant pathogens using agar-diffusion, MIC/MBC, and time-kill assays. AgNPs synthesized from crude-extract and active-fractions (F3, F4) were characterized by UV-Vis, DLS, TEM, and FTIR, with ion release behavior assessed via quantum chemical analysis. Bioactivity assays included biofilm inhibition, membrane permeability, ROS generation, intracellular leakage, cytotoxicity, hemolysis, and macrophage -profiling. In vivo efficacy was assessed in a murine systemic-infection model. F3 exhibited the strongest antibacterial activity, producing inhibition zones of 22.6 mm against E. coli and 20.9 mm against Klebsiella. F3-AgNP reduced MICs to 16 and 32 μg/mL, respectively, representing a 4-16-fold improvement. Docking revealed strong binding of a F3-derived polyketide (m/z 345.17) to RNA polymerase (-8.2 kcal/mol), outperforming fluoroquinolones. F3-AgNP inhibited biofilm formation by 88% and reduced bacterial burden by 3.8 log10 CFU in vivo, comparable to imipenem. It also modulated host immunity by reducing TNF-α and IL-6 while increasing IL-10, with low cytotoxicity and hemolysis. Pharmacokinetic analysis showed rapid systemic exposure with a 4.1 h half-life. F3-AgNP demonstrated potent antibacterial, antibiofilm, and immunomodulatory effects, supporting its potential as a translational candidate against resistant Gram-negative infections.
The body's coagulation system is best known for stopping bleeding, but during bacterial infections, it plays a much more complex role. On one hand, it helps trap and isolate bacteria by forming clots that prevent their spread, a frontline defense strategy known as immunothrombosis. On the other hand, many bacteria have learned to hijack this very system to their advantage. Some trigger clot formation to shield themselves from immune cells, while others dissolve clots to escape and invade new tissues. This review looks at how key pathogens, including Staphylococcus aureus, Streptococcus pyogenes, and Escherichia coli, interact with and manipulate the host's coagulation system. These microbial mechanisms can worsen infections and lead to serious complications like sepsis, blood clots, organ damage, and even death. By unpacking the delicate balance between protection and harm, we aim to highlight why understanding these interactions matters, not just for basic science, but also for improving how we diagnose and treat infection-related clotting disorders.
