Biofilms formed by multidrug-resistant (MDR) Pseudomonas aeruginosa and Acinetobacter baumannii are a major cause of chronic nosocomial infections and therapeutic failure. L-form antimicrobial peptides (AMPs) are rapidly degraded by proteases, whereas D-enantiomeric peptides offer enhanced resistance to proteases. Here, we synthesized L- and D-β-casein 197, a milk-derived AMP, and systematically compared their antibiofilm activities against eight clinical isolates of P. aeruginosa and A. baumannii. The D-form reduced biofilm biomass by up to 83% during formation and by up to 88% in preformed biofilms. Mechanistic analyses revealed that the D-form caused more extensive membrane disruption, as demonstrated by flow cytometry and transmission electron microscopy. Isothermal titration calorimetry showed that the D-form bound LPS with higher affinity (KD 0.8 μM vs 3.1 μM), and molecular docking identified additional hydrogen bonds with lipid A. The D-form also more effectively inhibited bacterial motility. Both peptides exhibited low cytotoxicity toward cells (>90% viability at 100 μM), and the D-form reduced bacteria-induced cytotoxicity and bacterial internalization in infected macrophages more effectively than the L-form. In a Galleria mellonella infection model, D-β-casein 197 significantly improved survival against P. aeruginosa no. R1 and A. baumannii no. 13 challenge over 96 h compared to the L-form and untreated infected controls, while larval survival remained comparable to PBS controls, indicating negligible host toxicity. These findings identify D-β-casein 197 as a potent antibiofilm peptide against MDR Gram-negative biofilms, with enhanced activity, and LPS-neutralization assays confirmed that its antimicrobial potency is, at least in part, attributable to its stronger LPS binding affinity.
The intestinal tract is a key immune organ and microecological system, where colonization resistance (CR) mediated by gut microbiota prevents pathogen invasion. Salmonella disrupts CR via type VI and type III secretion systems (T6SS/T3SS), inducing dysbiosis, inflammasome-driven inflammation, and intestinal barrier damage. This creates a self-reinforcing cycle:dysbiosis alters microbial metabolites, sustains inflammation, and enhances pathogen fitness, favoring chronic infection. This review integrates molecular mechanisms of microbiota disruption, inflammasome activation, and metabolic imbalance to explain how Salmonella overcomes CR. We also highlight microbiota-based countermeasures, including probiotics, natural antimicrobials, and phage therapy, as promising strategies to restore gut homeostasis.
Neisseria gonorrhoeae causes the sexually transmitted infection gonorrhea and is an obligate human pathogen, colonizing mucosal epithelia of the male urethra and the female endo/ectocervix, resulting in urethritis and cervicitis. These manifestations represent uncomplicated gonorrhea and highlight the gonococcus as a primarily mucosal pathogen. However, gonococci can ascend the female reproductive tract to cause pelvic inflammatory disease and may disseminate to distant anatomical sites. The gonococcus expresses a diverse array of virulence factors that mediate transmission, mucosal colonization, immune modulation, and disease progression. In this review, we outline the mechanisms of gonococcal transmission and colonization of the genital tract epithelium, and examine host–pathogen interactions that drive inflammation, immune evasion, and immune suppression. We also discuss the mechanisms underlying dissemination and the resulting spectrum of clinical outcomes. Continued investigation of gonococcal biology and host interactions will advance understanding of pathogenesis and support the development of improved treatments and preventative vaccines.
Produced by IRG1 in macrophages, itaconate has emerged as an immunometabolic hub at the host-pathogen interface. This review integrates itaconate’s roles in antimicrobial defense. We first examine how itaconate inhibits pathogen metabolism by targeting key enzymes including isocitrate lyase, fructose-bisphosphate aldolase, and inosine monophosphate dehydrogenase. Beyond direct inhibition, itaconate reprograms host immunity through SDH suppression, Nrf2 activation, ATF3 induction, and context-dependent NLRP3 regulation, and promotes lysosomal biogenesis via TFEB. Conversely, pathogens have evolved counter strategies including enzymatic degradation, biofilm formation, and immune microenvironment remodeling. We also summarize preclinical evidence supporting itaconate and derivatives’ therapeutic potential for infection-associated conditions. Finally, we appraise theoretical gaps and methodological challenges, offering guidance for future investigation in this rapidly advancing field.
Akabane virus (AKAV) initiates transcription in the cytoplasm via the cap-snatching mechanism. Cytoplasmic host mRNAs act as the primary cap donors, whereas the impact of their subcellular localization on the cap-snatching process remains unclear. Herein, we demonstrate that the AKAV-induced disassembly of polysomes, stress granules (SGs), and processing bodies (PBs) collectively facilitates viral cap-snatching. Mechanistically, AKAV infection activates the PKR-eIF2α signaling axis, leading to the disassembly of polysomes and subsequent translational shutoff. Intriguingly, the viral N protein disassembles SGs and PBs by competing for sequestered RNAs within these granules, whereas mutations of its RNA-binding residues abolish this activity. Moreover, PKR-eIF2α inhibition impairs AKAV replication and cap-snatching efficacy. Whereas, inhibition of SGs via G3BP1 knockdown or chemical agents significantly enhances viral replication and cap-snatching efficiency, indicating that polysomes and SGs disassembly favor caps acquisition. Additionally, N protein-mediated PBs disassembly protects mRNA from degradation, and PBs inhibition enhances cap-snatching. Taken together, AKAV has evolved a sophisticated strategy to reprogram mRNA distribution to create an optimal cellular environment for viral cap-snatching.
