Search Results (699)

Rheumatoid nodules are the most common extra-articular manifestation of rheumatoid arthritis. Long-term immunomodulatory therapies, including corticosteroids, used in the management of rheumatoid arthritis are associated with a higher risk of infections. Leishmaniasis is a neglected protozoal infection that may arise in these patients. Cutaneous presentation is the most common and is characterized by a wide spectrum of clinical manifestations and courses, depending on the interplay between species involved and the host’s immune response. Here, we report the rare and intriguing case of a patient with long-standing rheumatoid arthritis, chronically treated with systemic prednisone, whose rheumatoid nodules were colonized by Leishmania major. In this context, therapeutic strategies must be tailored to species and patient factors. This report expands the differential diagnosis of rheumatoid nodule, highlighting the importance of considering opportunistic infections in exuberant presentations, particularly in immunosuppressed patients coming from or travelling in endemic regions. Intracellular pathogens may exploit the localized immunological niche represented by the rheumatoid nodule of an immunocompromised host to survive and replicate undisturbed. It also underscores the value of the clinico-pathological correlation and the importance of integrating molecular analyses to identify unexpected microorganisms that can be hidden by concomitant disease, avoiding misdiagnosis, ensuring timely treatment, and improving patients outcomes. Full article

Background: Trypanosoma cruzi, the causative agent of Chagas disease, remains a major public health concern, and there is a continued need for new antitrypanosomal agents. Thiosemicarbazone (TSC) derivatives have emerged as a promising class of compounds with potential antiparasitic activity. Objectives: This study aimed to report the synthesis, characterization, and biological profiling of a novel series of thiosemicarbazone derivatives as antitrypanosomal agents against Trypanosoma cruzi. Methods: Fourteen new compounds and six previously described analogues were prepared and characterized by ¹H/¹³C nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). As a preliminary in vitro screen, activity was assessed by direct parasite counting in epimastigote and bloodstream trypomastigote forms, as tractable models of replicative and infective stages sharing core metabolic targets with intracellular amastigotes. Epimastigote potency was quantified as half-maximal effective concentrations (EC₅₀) derived from dose–response curves, whereas trypomastigote response was evaluated as percent viability after treatment at a fixed concentration of 20 µM. Mechanistic profiling included inhibition assays against the cysteine protease cruzipain (CZP) and selected redox defense enzymes, complemented by in silico similarity clustering and binding-pose affinity scoring. Results: A nitro-methoxy-substituted TSC showed potent CZP inhibition but limited trypomastigote efficacy, whereas brominated analogues displayed dual-stage activity independent of CZP inhibition. Tanimoto similarity analysis identified distinct structure–activity clusters, linking nitro-methoxy substitution to epimastigote selectivity and brominated scaffolds to broader antiparasitic profiles, with hydrophobicity and steric complementarity as key determinants. Enzymatic assays revealed no significant inhibition of cytosolic tryparedoxin peroxidase (cTXNPx) or glutathione peroxidase type I (TcGPx-I), suggesting redox disruption is not a primary mode of action. In vitro and in silico analyses showed low or no non-specific cytotoxicity under the tested conditions, supporting further optimization of these derivatives as antitrypanosomal preliminary hits. Key hits included derivative 3e (epimastigote EC₅₀ = 0.36 ± 0.02 µM) and brominated analogues 2c and 2e (epimastigote EC₅₀ = 3.92 ± 0.13 and 4.36 ± 0.10 µM, respectively), while docking supported favorable binding-pose affinity (e.g., ΔG_S-pose = −20.78 ± 2.47 kcal/mol for 3e). Conclusions: These results support further optimization of the identified thiosemicarbazone derivatives as preliminary antitrypanosomal hits and provide insight into structure–activity relationships and potential mechanisms of action. Full article

Host–virus relationships regulate every phase of viral infection and critically influence course of illness and the effectiveness of treatment. Viruses utilize host receptors, intracellular trafficking routes, metabolic programs, and immunological signaling networks to introduce infection, while host cells use innate and adaptive immune responses that both limit viral replication and, in certain situations, cause tissue damage. Given the fast viral evolution and drug resistance linked to virus-directed therapy, there is growing proof that these host-dependent mechanisms are appealing and underutilized targets for antiviral treatment. Recent developments in single-cell technology, proteomics, and functional genomics have made it possible to systematically identify host dependency and restriction factors shared by different viral families, exposing common molecular vulnerabilities that might be targeted therapeutically. This review integrates current knowledge of virus–host interplay via a translational lens, highlighting processes that directly guide the formation of host-directed antivirals and immune-regulating treatments. We emphasize host processes involved in viral entry, replication, and immune signaling that have shown therapeutic significance, while illustrating the difficulties of balancing antiviral effectiveness with immunopathology. By framing host–virus interactions through a therapeutic lens, this review attempts to offer a targeted and translationally relevant viewpoint for next-generation antiviral research. Full article

Background/Objectives: Rotavirus remains a major cause of severe acute gastroenteritis in infants worldwide. The suboptimal efficacy of current vaccines underscores the need for alternative microbiome-based interventions, including postbiotics. Extracellular vesicles (EVs) from probiotic and commensal E. coli strains have been shown to mitigate diarrhea and enhance immune responses in a suckling-rat model of rotavirus infection. Here, we investigate the regulatory mechanisms activated by EVs in rotavirus-infected enterocytes. Methods: Polarized Caco-2 monolayers were used as a model of mature enterocytes. Cells were pre-incubated with EVs from the probiotic E. coli Nissle 1917 (EcN) or the commensal EcoR12 strain before rotavirus infection. Intracellular Ca²⁺ concentration, ROS levels, and the expression of immune- and barrier-related genes and proteins were assessed at multiple time points post-infection. Results: EVs from both strains exerted broad protective effects against rotavirus-induced cellular dysregulation, with several responses being strain-specific. EVs interfered with viral replication by counteracting host cellular processes essential for rotavirus propagation. Specifically, EV treatment significantly reduced rotavirus-induced intracellular Ca²⁺ mobilization, ROS production, and COX-2 expression. In addition, both EV types reduced virus-induced mucin secretion and preserved tight junction organization, thereby limiting viral access to basolateral coreceptors. Additionally, EVs enhanced innate antiviral defenses via distinct, strain-dependent pathways: EcN EVs amplified IL-8-mediated responses, whereas EcoR12 EVs preserved the expression of interferon-related signaling genes. Conclusions: EVs from EcN and EcoR12 act through multiple complementary mechanisms to restrict rotavirus replication, spread, and immune evasion. These findings support their potential as effective postbiotic candidates for preventing or treating rotavirus infection. Full article

The COVID-19 pandemic has profoundly affected societies around the world. Although the emergency phase of coronavirus disease 2019 (COVID-19) has ended, the threat it poses remains persistent. This review aims to clarify the mechanisms of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection to support effective management of the disease. A central focus is the host cellular response to the viral infection, with particular emphasis on the role of cytokines. Cytokines play a dual role in antiviral defense: they contribute to the inhibition of viral replication and facilitate the clearance of pathogens, yet dysregulated cytokine responses can result in severe immunopathology. Interferons (type I, type II, and type III) and other cytokines are pivotal in activating intracellular antiviral mechanisms and in orchestrating the recruitment of immune cells through extracellular signaling. Effective immune responses to viral infections are governed not only by primary immune cells—such as dendritic cells, T lymphocytes, and B lymphocytes—but also by the local cytokine milieu shaped by infected and neighboring cells. Given the presence of endogenous inhibitors and autoantibodies in vivo, it is essential to evaluate the functional activity of cytokines in clinical samples. We propose a novel approach to quantify biologically active cytokine levels. Full article

Cisplatin, a platinum-based compound, is a cornerstone of modern chemotherapy and remains widely used against a variety of solid tumors, including testicular, ovarian, lung, bladder, and head and neck cancers. Its anticancer activity is primarily attributed to the formation of DNA crosslinks, which obstruct replication and repair, ultimately leading to apoptosis. However, the clinical value of cisplatin is constrained by two major challenges: its toxic profile and the development of resistance. Cisplatin toxicity arises from its interaction not only with tumor DNA but also with proteins and nucleic acids in healthy tissues, resulting in a range of adverse effects, including, but not limited to, nephrotoxicity, ototoxicity, neurotoxicity, and gastrointestinal injury. In pediatric patients, permanent hearing loss represents a particularly debilitating complication. On the other hand, tumor cells can evade cisplatin cytotoxicity through diverse mechanisms, including reduced intracellular drug accumulation, enhanced DNA repair, detoxification by thiol-containing molecules, and alterations in apoptotic signaling. These resistance pathways severely compromise treatment outcomes and often necessitate alternative or combination strategies. This review examines the chemical structure of cisplatin, the molecular mechanisms of cisplatin cytotoxicity and cisplatin-induced resistance, as well as the main applications in cancer management and the complications associated with its clinical use. Full article

Abnormal lipid metabolism is a key feature of many diseases. Therefore, investigating its underlying mechanisms is of great importance. Recently, blue light has shown promise as a drug-free way to influence energy metabolism, relying on the light-sensitive protein Opsin 3 (Opn3). This study aimed to investigate the effects of blue light irradiation on lipid droplet degradation in cells and its molecular mechanism, while also evaluating its potential antiviral effects. The results demonstrate that exposure to 470–480 nm blue light significantly reduced oleic-acid-induced intracellular lipid droplet accumulation and decreased triglyceride and total cholesterol levels, an effect dependent on the Opn3. It was found that blue light affects the Pparα signaling pathway through Opn3, and, at the same time, blue light and Opn3 promote autophagy mediated by p62 protein, thereby cooperatively regulating lipid droplet degradation. In Opn3 knockout cells, blue-light-induced lipid droplet degradation, nuclear accumulation of Pparα, and autophagic effects were all suppressed. Additionally, the study unexpectedly observed that blue light, via Opn3, significantly suppressed the replication of VSV, H1N1 and EMCV and alleviated virus-induced cell death and inflammatory responses. This study reveals the critical role of the blue light–Opn3-Pparα/p62 axis in regulating lipid droplet degradation in hepatocytes and identifies a novel antiviral function of Opn3-mediated blue light exposure. These findings provide a new theoretical basis and potential targets for innovative therapeutic strategies against metabolic diseases and viral infections. Full article

Outcomes of influenza virus infection vary widely across individuals, reflecting not only viral genetics and host factors but also the composition and function of the airway microbiome. Over the past few years, mechanistic work has clarified how specific commensals (for example, Staphylococcus epidermidis and Streptococcus oralis) restrict influenza replication by priming epithelial interferon-λ programs, reshaping intracellular metabolite pools (notably polyamines), dampening host protease activity, and maintaining barrier integrity; meanwhile, pathobionts (notably Staphylococcus aureus and Streptococcus pneumoniae) can enhance viral fitness via secreted proteases and neuraminidases that activate hemagglutinin and remodel sialylated glycoconjugates and mucus, setting the stage for secondary bacterial disease. Recent studies also highlight the gut–lung axis: gut microbiota-derived short-chain fatty acids (SCFAs), especially acetate, protect tight junctions and modulate antiviral immunity in influenza models. Together, these insights motivate translational strategies—from intranasal live biotherapeutics (LBPs) to metabolite sprays and decoy/dual neuraminidase approaches—that complement vaccines and antivirals. We synthesize recent evidence and outline a framework for leveraging the airway microbiome to prevent infection, blunt severity, and reduce transmission. Key priorities include strain-level resolution of commensal effects, timing/dosing windows for metabolites and LBPs, and microbiome-aware clinical pathways for anticipating and averting bacterial coinfection. Overall, the airway microbiome emerges as a tractable lever for influenza control at the site of viral entry, with several candidates moving toward clinical testing. Full article

Vimentin is a type III intermediate filament protein that maintains cellular integrity, organelle positioning, and resilience to mechanical stress, but it is increasingly recognized for its dynamic change in viral infection. Viral infection causes vimentin filament disassembly into soluble oligomers with hydrophobic and acidic interfaces conducive to viral binding. These oligomers are recruited to the cell surface, where they act as viral co-receptors, facilitating viral attachment and entry. Upon entry, the viral protein induces post-translational modifications in intracellular vimentin filaments undergoing rearrangement processes, including disassembly into oligomers and then reassembly into cage-like structures that encapsulate viral replication complexes. Whether these structures promote viral replication or represent a host-imposed defense remains open. Our findings highlight the pro-viral “shield” and anti-viral “sabotage” role, a context-dependent role of vimentin during viral infection. Importantly, we offer a perspective encompassing structural biology and molecular and cellular signaling insights into vimentin dynamics, an approach that has not been explored in the current literature. We further propose that targeting vimentin is an innovative strategy for anti-viral intervention. Full article

Chronic hepatitis B virus (HBV) infection remains a global public health challenge, and the currently approved medications can not achieve a cure. Synthetic triterpenoids have shown promising therapeutic potential for liver pathologies. In our search for novel antiviral agents against HBV, we found that two triterpenoids, 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) and CDDO-ethyl amide (CDDO-EA), significantly inhibited HBV DNA replication. Further mechanistic investigation indicated that these two compounds did not significantly alter the levels of total HBV pgRNA, but dramatically reduced extracellular pgRNA and intracellular encapsidated pgRNA in a dose-dependent manner. Western blot analysis indicated minimal effects on core protein expression. Interestingly, using a particle gel assay, we observed that CDDO and CDDO-EA promoted the formation of empty capsids with no alteration in electrophoretic mobility. Moreover, we demonstrated that both compounds modulated the phosphorylation status of the core protein. Further cellular thermal shift assay (CETSA), surface plasmon resonance (SPR) assay, and molecular docking analyses collectively suggested that CDDO and CDDO-EA could bind directly to the dimer–dimer interfaces of HBV core protein. Finally, a synergistic effect was observed between CDDO-EA and lamivudine in reducing intracellular and extracellular HBV DNA levels. Our findings indicate that triterpenoids CDDO and CDDO-EA are new mechanistically type of HBV capsid assembly modulators and warranted for further development as lead compounds against HBV. Full article

White-nose syndrome (WNS) is an infectious disease of bats caused by the psychrophilic fungus Pseudogymnoascus destructans. Phenazine-1-carboxylic acid (PCA) is a microbial secondary metabolite with broad-spectrum antifungal activity. Previous studies show that PCA suppresses the growth of P. destructans at low concentrations, yet its mechanism remains unclear. Here, we evaluated the in vitro antifungal activity of PCA. We then investigated its potential mechanism using physiological and biochemical assays, as well as integrated transcriptomic and metabolomic analyses. PCA showed effective antifungal activity against P. destructans (EC₅₀ = 32.9 μg/mL). Physiological and biochemical assays indicated that PCA perturbed cell wall organization and increased membrane permeability, leading to leakage of intracellular contents. It also induced oxidative stress, DNA damage, and apoptosis. Multi-omics integration revealed that PCA markedly perturbed cell wall and membrane metabolism, virulence factor expression, and energy metabolism. It provoked oxidative stress while downregulating genes involved in the cell cycle, DNA replication, and repair. Together, these findings delineate the inhibitory effects of PCA on P. destructans in vitro, provide initial mechanistic insights into its antifungal action, and suggest that PCA merits further evaluation as a possible component of environmentally compatible strategies for WNS management. Full article

RNA viruses, such as SARS-CoV-2 and influenza, pose a persistent threat to global public health. Their high mutation rates undermine the effectiveness of conventional direct-acting antivirals (DAAs) and facilitate drug resistance. As obligate intracellular parasites, RNA viruses rely extensively on host cellular machinery and metabolic pathways throughout their life cycle. This dependency has prompted a strategic shift in antiviral research—from targeting the mutable virus to targeting relatively conserved host dependency factors (HDFs). In this review, we systematically analyze how RNA viruses exploit HDFs at each stage of infection: utilizing host receptors for entry; remodeling endomembrane systems to establish replication organelles; hijacking transcriptional, translational, and metabolic systems for genome replication and protein synthesis; and co-opting trafficking and budding machinery for assembly and egress. By comparing strategies across diverse RNA viruses, we highlight the broad-spectrum potential of HDF-targeting approaches, which offer a higher genetic barrier to resistance, providing a rational framework for developing host-targeting antiviral therapies. Full article

Background/Objectives: Chagas disease, caused by Trypanosoma cruzi, remains a major neglected tropical disease with limited therapeutic options restricted to benznidazole and nifurtimox, both associated with significant toxicity and reduced efficacy during chronic infection. Seeking novel, safe, and sustainable chemotherapeutic candidates, two new saturated cardanol-derived phospholipid analogs—LDT10 and LDT119—were rationally designed based on the molecular scaffold of miltefosine and biosourced from cashew nut shell liquid (CNSL). This study aimed to evaluate the pharmacokinetic properties of these compounds in silico and assess their antiparasitic activity, cytotoxicity, and morphological and ultrastructural effects on all developmental forms of T. cruzi in vitro. Materials and Methods: In silico ADMET predictions (SwissADME, pkCSM) were performed to determine bioavailability, pharmacokinetic behavior, CYP inhibition, mutagenicity, and hepatotoxicity. Antiproliferative activity was evaluated in epimastigotes, trypomastigotes, and intracellular amastigotes using dose–response assays and flow cytometry. Cytotoxicity was assessed in HEPG2 and HFF-1 cells using resazurin-based viability assays. Morphological and ultrastructural alterations were investigated through scanning (SEM) and transmission (TEM) electron microscopy. Reactive oxygen species (ROS) generation was quantified with H₂DCFDA after 4 h and 24 h of exposure. Results: In silico analyses indicated favorable drug-like profiles, high intestinal absorption (>89%), absence of mutagenicity or hepatotoxicity, and non-penetration of the blood–brain barrier. LDT10 was not a P-gp substrate, and LDT119 acted as a P-gp inhibitor, suggesting reduced efflux and higher intracellular retention. Both compounds inhibited epimastigote proliferation with low IC₅₀ values (LDT10: 0.81 µM; LDT119: 1.2 µM at 48 h) and reduced trypomastigote viability (LD₅₀ LDT10: 2.1 ± 2 µM; LDT119: 1.8 ± 0.8 µM). Intracellular amastigotes were highly susceptible (IC₅₀ LDT10: 0.48 µM; LDT119: 0.3 µM at 72 h), with >90% inhibition at higher concentrations. No cytotoxicity was observed in mammalian cells up to 20 µM. SEM revealed membrane wrinkling, pore-like depressions, rounded cell bodies, and multiple flagella, indicating cell division defects. TEM showed Golgi disorganization, autophagic vacuoles, mitochondrial vesiculation, and abnormal kinetoplast replication, while host cells remained structurally preserved. Both compounds induced significant ROS production in trypomastigotes after 24 h in a dose-dependent manner. Conclusions: LDT10 and LDT119 exhibited potent and selective in vitro activity against all developmental stages of T. cruzi, with low micromolar to submicromolar IC₅₀/LD₅₀ values, minimal mammalian cytotoxicity, and extensive morphological and ultrastructural damage consistent with disruption of phospholipid biosynthesis pathways. Combined with favorable in silico pharmacokinetic predictions, these CNSL-derived phospholipid analogs represent promising candidates for future Chagas disease chemotherapy and warrant further in vivo evaluation. Full article

Streptococcus suis is an important zoonotic pathogen responsible for severe infections in pigs and humans. Its capacity to survive within phagocytic cells is considered a key virulence mechanism that contributes to dissemination and persistence in host tissues. This study employed comparative proteomic profiling to investigate intracellular adaptation of S. suis serotypes 2 (SS2) and 14 (SS14) during infection of human U937 macrophages. Five isolates originating from humans and pigs were analyzed using gel electrophoresis with liquid chromatography–tandem mass spectrometry (GeLC–MS/MS), revealing 118 differentially expressed proteins grouped into 11 functional categories. Translation-related proteins represented the largest group (48%), including upregulated ribosomal subunits (30S: S2, S5, S7, S8, S12, S15; 50S: L1, L5, L18, L22, L24, L33, L35) and translation factors such as GidA/TrmFO and RimP. Enrichment of carbohydrate metabolism and DNA replication proteins, including phosphoenolpyruvate carboxylase (PEP), UDP-N-acetylglucosamine pyrophosphorylase (GlmU), and ATP-dependent DNA helicase RuvB, indicated metabolic reprogramming and stress adaptation under intracellular conditions. Stress-response proteins such as molecular chaperone DnaK were also induced, supporting their multifunctional, “moonlighting” roles in virulence and host interaction. Comparative analysis showed that SS2 expressed a broader range of adaptive proteins than SS14, consistent with its higher virulence potential. These findings reveal conserved intracellular responses centered on translation, energy metabolism, and stress tolerance, which enable S. suis to survive within human macrophages. Integration of these intracellular proteomic signatures with previous exoproteomic, peptidomic, and network-based studies highlights translational and metabolic proteins—particularly DnaK, enolase, elongation factor EF-Tu, and GlmU—as multifunctional candidates linking survival and immunogenicity. This work establishes a comparative proteomic foundation for understanding S. suis intracellular adaptation and highlights potential targets for future vaccine or therapeutic development against this zoonotic pathogen. Full article

Autophagy is a highly conserved catabolic process in eukaryotic cells that maintains cellular homeostasis by degrading damaged or superfluous intracellular components. Autophagy plays a dual, paradoxical role during viral infection. However, for most viruses, the induction of autophagy provides a favorable intracellular environment for the full completion of their life cycles. Most viruses that benefit from autophagy adopt a “regulate but not destroy” strategy, i.e., they initiate the autophagic process while suppressing their immune system through mechanisms such as blocking autophagosome-lysosome fusion. This allows them to avoid self-elimination while redirecting other functions of the autophagic machinery—for instance, utilizing autophagy-derived structures such as autophagosomes and double-membrane vesicles (DMVs) as specialized sites for viral genome replication, particle assembly, and maturation. The maintenance of cellular homeostasis by autophagy is crucial for the establishment of viral infection, as it provides a viable cellular microenvironment for viral replication; after infection occurs, inhibiting the degradative function of autophagy becomes a key strategy for viruses. Although canonical degradative autophagy exerts a negative effect on most viruses, redirected nondegradative autophagic structures and repurposed autophagic mechanisms are essential for the efficient replication of various viruses. In-depth analysis of this dynamic virus-autophagy interplay will provide important insights for elucidating virus-host interactions and developing autophagy-targeted antiviral strategies. Full article