Toxins

Streptococcal pyrogenic exotoxin C (SpeC) is a prototypical superantigen produced by group A Streptococcus. It potently activates a broad subset of T lymphocytes via a bridging interaction involving TCR{beta}-SpeC-MHC-II. Our recent work demonstrated that SpeC induced profound release of IL-8 from human pharyngeal epithelial cells and this effect was reversible through a specific point mutation in SpeC. This study systematically investigated cellular signaling pathways using integrated transcriptomic profiling and Western blot analysis, with a focus on membrane-associated receptors and downstream intracellular signaling effectors. Our results demonstrate that this biological process is critically associated with the activation of Erk1/2, p38 MAPK and NF-{kappa}B signaling cascade. This study identifies a novel mechanism through which a bacterial superantigen target epithelial cells-the body primary physical barrier and first line of innate immune defense.

BackgroundRising antimicrobial resistance rates, require new therapeutic approaches such as antimicrobial peptides (AMPs), which are part of the innate immune defense, as alternatives to antibiotics. In this study, we aim to unravel the antibacterial activity of human histone H1.2 peptide against Pseudomonas aeruginosa and its potential immune modulatory role. MethodsWe used a hemofiltrate peptide database for antimicrobial peptide prediction to identify novel human AMPs. Thirteen sequences of histone H1 were identified as putative AMPs, synthesized, and tested against bacterial ESKAPE pathogens in a radial diffusion assay. SYTOX green assay, electrophoretic mobility shift assay, and differential proteomics assays were conducted to determine the mode of action of H1.2 peptide fragment. A crystal violet assay was performed to evaluate the inhibition of biofilm formation. The cytotoxicity of the peptide was tested in LDH and Alamar assays. Finally, to visualize the contributions of H1.2 in NETs formation, scanning electron microscopy was performed. ResultsThe H1.2 peptide inhibited the growth of P. aeruginosa in a dose and pH-dependent manner without cytotoxicity towards mammalian THP-1 cells. It acts on intracellular targets to inhibit the growth of P. aeruginosa. STRING analysis from the differential proteomics assay showed that H1.2 targets the downregulation of proteins involved in the biogenesis of outer membrane proteins, including the folding and trafficking of outer membrane proteins across the cytoplasmic membrane. Scanning electron microscopy images showed that H1.2 forms NET-like structures capable of trapping and immobilizing P. aeruginosa. ConclusionThe characterized antimicrobial activity of H1.2 points to a role for human histone H1 fragments in innate immunity and may represent a promising approach for the development of novel antibacterial therapies. Graphical Summary O_FIG O_LINKSMALLFIG WIDTH=192 HEIGHT=200 SRC="FIGDIR/small/724237v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@1778ddborg.highwire.dtl.DTLVardef@26430org.highwire.dtl.DTLVardef@ffbfa2org.highwire.dtl.DTLVardef@7e38ae_HPS_FORMAT_FIGEXP M_FIG C_FIG Sec transport and BAM complex system including chaperone proteins and quality control proteases are inhibited by H1.2 in Pseudomonas aeruginosa.Outer membrane proteins (OMPs) are synthesized in the cytoplasm and transported across the inner membrane via the Sec translocase, assisted by SecA/SecB or ribosomes. In the periplasm, they are escorted by chaperones such as SurA to the BAM complex for insertion into the outer membrane. Here, we show that H1.2, an antimicrobial peptide, targets membrane biogenesis in P. aeruginosa through downregulating Sec translocase (SecA/SecB and SecYEG), SurA, and BAM complex. Therefore, leading to improper transfer, folding and insertion of OMPs into the outer membrane. Normally, misfolded proteins are degraded by the protease MucD to prevent toxic aggregation in the bacteria. However, with H1.2 inhibiting MucD the proteotoxic stress is exacerbated, ultimately compromising bacterial homeostasis and viability. Figure created using BioRender.com.

Treponema pallidum ssp. pallidum, the causative agent of syphilis, has a small proteome and encompasses numerous strains. Knowledge gaps remain in understanding the molecular mechanisms of pathogenesis of this bacterium, as well as the structure and function of the full complement of proteins encoded by T. pallidum. Here, an AI-based structure-to-function modeling workflow was used to investigate the complement of proteins encoded by T. pallidum. High-confidence structure models were generated for 976 T. pallidum proteins, covering 99% of the proteome. Analysis of the generated models using the protein structure comparison server DALI enabled high-confidence, structure-based functional annotation of 877 T. pallidum proteins, including 240 of the 323 proteins of unknown function encoded by this pathogen. Additionally, 63 putative pathogenesis related proteins (PPRPs) and seven treponemal proteins with previously uncharacterized similarity to outer membrane proteins (OMPs) from Gram-negative bacteria were identified. A workflow for B cell epitope (BCE) prediction identified 1133 surface-exposed, host-facing potential epitopes in known and predicted T. pallidum OMPs, of which 92 were prioritized based on bioinformatic analyses, biophysical properties, amino acid sequence conservation, and previous protein expression data. This work provides insight into T. pallidum pathogenesis through structure modeling-based functional annotation, including characterization of proteins of unknown function. This study also informs syphilis vaccine design by identifying new potential T. pallidum OMPs, as well as host-facing regions of T. pallidum OMPs that have conserved amino acid sequences in globally circulating strains. Statement of importance/impactThis study presents the first AI-based global structure modeling-to-function analysis of the proteome of Treponema pallidum, the bacterium that causes syphilis. Structure-based functional predictions of previously uncharacterized proteins, including proteins potentially involved in virulence, provide novel insight into mechanisms of pathogenesis. The work also informs syphilis vaccine development by the identification and structural characterization of new candidate vaccine proteins in globally circulating strains of T. pallidum.

Bacillus thuringiensis INTA Mo4-4 was characterized phenotypically, genomically, and for insecticidal activity against Alphitobius diaperinus. Microscopy revealed rare flat rectangular parasporal crystals, and SDS-PAGE identified a ca. 67 kDa protein, similar to B. thuringiensis serovar morrisoni strain tenebrionis DSM-2803, which was proteolytically processed to a ca. 55 kDa fragment. Genomic analysis showed a 5.99 Mb genome with 99.43% completeness, clustering phylogenetically with B. cereus and B. thuringiensis. High genomic similarity was observed with B. thuringiensis svar. morrisoni BGSC 4AA1, confirmed by MLST analysis assigning it to ST-23. The genome encodes an interesting arsenal of pesticidal proteins showing significant similarity to Cry3Aa, Mpp23Aa, Xpp37Aa, Mpp5Ab, Vpb1Ad, Vpb1Ae, Vpa2Ab, Vpa2Ba, Vpa2Bb and Spp1Aa, with demonstrated toxicity against coleopteran pests. Biosynthetic gene clusters for toyoncin, fengycin, and bacillibactin were identified. Dose-response bioassays showed that INTA Mo4-4 was nearly four times more toxic to A. diaperinus larvae (LC50 136.9 {micro}g/ml) than DSM-2803 (LC50 540.5 {micro}g/ml), with the difference being statistically significant. No teratological effects were observed on Musca domestica. These findings suggest that INTA Mo4-4 is a promising candidate for the biological control of A. diaperinus.

TRPA1 is a non-selective cation channel that plays a crucial role in several pain and inflammatory conditions. Agents reducing membrane cholesterol decrease TRPA1 activation, but it remains unclear how cholesterol-lowering medications affect TRPA1 function. Given that TRPA1 is activated by a wide variety of chemicals, we explored whether statins have acute effects on this channel. We found that five commonly used statins activate human and mouse TRPA1 in a reversible and concentration-dependent manner. The effective concentrations were above the micromolar range, in the order: simvastatin {approx} lovastatin < fluvastatin < atorvastatin < pravastatin. Statin-induced activation was not correlated to changes in membrane order, nor mediated by N-terminal cysteine residues contributing to electrophilic compound agonism. Molecular docking calculations and the functional characterization of single-point mutants revealed two separate putative binding sites, one situated close to the kink of transmembrane segment 5 (TM5) and the other at the interface between TM4 and TM5. The mTRPA1 inhibitor A-967079 largely abrogated the response to the electrophilic agonist allyl isothiocyanate, but had weaker and varied effects across different statins and menthol. Mutation T877L strongly altered the effect of A-967079, also in an agonist-dependent manner, suggesting competitive binding between this antagonist and the non-electrophilic agonists. The identification of two distinct agonist binding sites may help explaining how TRPA1 is able to respond to a large variety of non-electrophilic compounds, while the finding of competitive interactions at one of these sites may help guide the development of agonist-specific antagonists of therapeutic relevance.

IntroductionThe mitochondrial citrate carrier (CiC), which mediates the transport of citrate across mitochondria, has been implicated in various diseases, but its role in kidney tubules is unclear. Here, we unraveled a novel role of CiC in tubular metabolism in the context of antibiotics-induced acute tubular injury (ATI). MethodsATI was induced by administration of vancomycin and gentamycin for 48 hours in mice (V+G-ATI). Tubular-specific CiC knockout (KO) was induced by adeno-associated virus (AAV) serotype 9 encoding Cre recombinase driven by KSP promoter (AAV9-Ksp-Cre) injection. Unbiased proteomic and metabolomic analyses were performed in CiC KO mouse kidneys. We performed in vivo 13C metabolic flux analysis to elucidate metabolic alterations in ATI and the effect of CiC KO. ResultsIn this study, V+G-induced ferroptosis, oxidative damage, and extensive ATI in mice were alleviated by CiC KO. Metabolic reprogramming induced by CiC KO increased mitochondrial TCA cycle intermediates, including alpha ketoglutarate (AKG), and elevated levels of the endogenous antioxidant glutathione (GSH). Supplementation with AKG or GSH attenuated V+G-ATI in mice. Tracking of the 13C pyruvate / lactate revealed an increased flux of glucose oxidation pathway in V+G-ATI. Interestingly, tubular-specific CiC KO expands the effective TCA cycle pool reserve space, which may contribute to mitigation of ROS. The beneficial metabolic alteration in CiC KO requires AKG and glutamate, as simultaneous inhibition of mitochondrial transporters of AKG and glutamate attenuated the cytoprotective effects of CiC KO against antibiotic-induced oxidative damage. ConclusionsThis is the first study to demonstrate the role of mitochondrial CiC in kidney tubular epithelial cells, showing that it induces metabolic alterations that protect against antibiotic-induced ATI.

Coevolution proceeds through the evolution of traits that mediate ecological interactions and evolutionary outcomes. In the arms race between toxic Pacific newts (Taricha) and their garter snake predators (Thamnophis), this interface involves tetrodotoxin (TTX), an antipredator defense that inhibits nerve and muscle function by blocking voltage-gated sodium channels. In response, snakes have evolved TTX-resistant channels, in some cases leading to snake populations that are nearly invulnerable to TTX. For decades, newt TTX has been treated as a single defensive trait, yet TTX occurs as a family of structurally related analogs that may represent alternative defenses against snakes. Here, we characterize TTX analog diversity in all four species of Taricha and evaluate how these compounds interact with the sodium channels in coevolved garter snakes. Using LC-MS analysis of newt skin secretions, we detected a diverse suite of TTX analogs previously unrecognized in Pacific newts. We then used molecular docking models to evaluate interactions between various TTX analogs and variants of the skeletal muscle channel (Nav1.4) that span the range of TTX resistance in garter snakes. We found that some TTX analogs docked better than canonical TTX in resistant snake channels. Notably, we show that 11-deoxy-4-epi-TTX and 11-deoxy-TTX have favorable interactions with hydrophobic amino-acid substitutions in extremely resistant garter snake sodium channels, potentially circumventing predator resistance to canonical TTX. Our results suggest a complex arms race involving multiple newt TTX analogs and multiple snake sodium channel variants. As such, newts may keep pace with snakes by diversifying their arsenal of chemical weapons.

Malaria is caused by Plasmodium parasites, and its clinical symptoms are a result of parasite invasion of red blood cells and the subsequent cycles of replication and proliferation. In human populations, Plasmodium vivax is responsible for the most widely distributed recurring malaria infections whereas Plasmodium falciparum inflicts the most mortality and morbidity. One well-characterized family of adhesins involved in red blood cell invasion is the reticulocyte-binding-like protein homolog family, known as the RBL superfamily which includes the PfRh family in P. falciparum and PvRBP family in P. vivax. Here we report a collection of nanobodies against three members of this adhesin family, PfRh5, PfRh4 and PvRBP2b. Nanobodies against these Plasmodium adhesins bind with high affinity across several epitopes and can block receptor engagement and inhibit parasite invasion of red blood cells. Using computational design, we generated stabilized PfRh4 variants that encompass the conserved scaffold present in the PfRh and PvRBP families of adhesins and show that several variants with improved expression retained binding to mouse monoclonal antibodies, nanobodies and Complement Receptor 1, the human receptor for PfRh4. We also observed that most of the inhibitory nanobodies against the three antigens recognized the conserved structural scaffold that define this family of adhesins. These results demonstrate the potential of nanobodies to block malaria parasite invasion into red blood cells.

Syntaxin-binding protein 1 (STXBP1) mutations lead to severe epilepsy, intellectual disability, developmental delay, and movement disorder. Effective treatments for these conditions do not exist. Recent studies in Munc18-1 (STXBP1) C. elegans models demonstrate that 4-phenylbutyrate (4-PBA) or related pharmacological chaperones stabilize Munc18-1 protein levels and rescue locomotion deficits. These studies suggest a novel treatment strategy for these patients. Here, we used a stxbp1a zebrafish model with a profound movement disorder to screen 4-PBA and alternative structural analogs identified using artificial intelligence (AI)-based screening. Automated locomotion assays conducted on larval stxbp1a mutant zebrafish at 5 days post-fertilization (dpf) confirm and extend the movement disorder endophenotype. Drug treatment (4-PBA or 16 identified candidates) failed to rescue the stxbp1a mutant zebrafish locomotion deficit. Electrophysiology studies in a stxbp1b zebrafish model characterized by spontaneous seizure activity (i.e., epilepsy) failed to detect a reduction in ictal-like events with 4-PBA treatment. Taken together, our results suggest caution in repurposing 4-PBA or related compounds for treatment of STXBP1 disorders.

IntroductionErgosterol-targeting azoles are widely used in the treatment of Candida albicans infection. In addition to direct antifungal activity, azoles are known to enhance neutrophil-mediated killing of C. albicans, but the underlying mechanisms remain unclear, particularly whether ergosterol depletion directly modulates host immune responses. Gap StatementIt remains unknown whether reduced ergosterol levels alone, independent of broader disruption to sterol biosynthesis and fungal morphogenesis, influence neutrophil antifungal activity. AimThis study aimed to determine how genetic disruption of late-stage ergosterol biosynthesis affects neutrophil-mediated responses to C. albicans. MethodologyDoxycycline-repressible GRACE mutants targeting late-stage ergosterol biosynthesis genes (ERG4, ERG5, ERG3 and ERG28) were co-incubated with primary human neutrophils. Fungal survival, oxidative burst, phagocytosis, neutrophil extracellular trap (NET) formation and cell wall composition were assessed. ResultsAll ergosterol-deficient strains induced elevated neutrophil reactive oxygen species (ROS) production; however, only ERG4 depletion was associated with enhanced fungal clearance. This phenotype correlated with increased phagocytosis and reduced NET formation. Cell wall analysis revealed no changes in total chitin or mannan content but demonstrated significantly increased surface exposure of {beta}-1,3-glucan in ERG4-depleted cells. ConclusionThese findings indicate that disruption of late-stage ergosterol biosynthesis, particularly via ERG4, enhances neutrophil antifungal responses and is associated with increased {beta}-glucan exposure. This study highlights a potential role for ergosterol in immune evasion and suggests that targeting terminal steps of the pathway may improve host-mediated clearance of C. albicans.

Chitosan is an oligosaccharide derived from chitin that is protonated at acidic pH to form a polycation. Its positive charge promotes the interaction with negatively charged components of the yeast cell surface, which has been associated with increased cell permeability and growth inhibition. In this study, we investigated the interaction of chitosan with the cell surface and its permeabilizing capacity in three yeast species displaying distinct susceptibility profiles, Saccharomyces cerevisiae, Candida albicans and Debaryomyces hansenii. We evaluated the correlation between differential susceptibility and chitosan association at the cell surface, as well as cell permeabilization, by integrating growth analyses with surface-binding assays, including FITC-conjugated chitosan to monitor surface association and cellular integration over time, and ultrastructural examination by transmission electron microscopy (TEM). Our results showed that chitosan exhibited varying effects on the growth and permeability of each yeast strain, with D. hansenii being the most susceptible. Furthermore, we observed the incorporation of chitosan onto the cell surface and confirmed its role as a permeabilizing agent. Finally, we used chitosan-induced permeabilization as a method to measure the activity of selected enzymes in situ, demonstrating its potential for studying metabolic functions in permeabilized yeast cells. Overall, our findings establish chitosan as a strain-dependent antifungal agent and a useful tool for functional biochemical analyses in yeast.

Fungal contamination of food with yeast and moulds is associated with major economic losses due to spoilage and also poses health risks in the form of mycotoxin production. The strain Pantoea agglomerans APC 4211 isolated from leaves of Ilex aquifolium (holly tree) has broad spectrum antifungal activity against a variety of food spoilage fungi. Genomic analysis of the strain confirmed the presence of biosynthetic gene clusters potentially encoding for the enzymatic machinery required for the production of the antifungal lipopeptide herbicolin A. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of the cell-free supernatant (CFS) confirmed the presence of molecular masses corresponding to herbicolin A (1300.8 Da), and herbicolin B (1138 Da). Purified herbicolin A has desirable properties for biotechnological applications, including potent antifungal activity against a range of spoilage fungi, thermal stability and resistance to proteases. Herbicolin A has low cytotoxicity against epithelial cell lines and has minimum inhibitory concentrations (MICs) lower than those of some commercial antifungal drugs (0.2 - 2.5 {micro}g/ml). In a model dairy system (10% skim milk), herbicolin A demonstrated excellent solubility and stability, effectively eliminating Aspergillus niger and Penicillium notatum at a concentration of 5 {micro}g/mL. In conclusion, herbicolin A is a potent, naturally occurring antifungal agent with the potential to be applied as a biopreservative in food systems, providing a safe, clean-label, and efficient compound for synthetic preservatives replacement. HighlightsO_LIHerbicolin A has a strong potential as a natural preservative for food protection C_LIO_LIHerbicolin A shows lower MICs than several antifungal agents C_LIO_LIHerbicolin A is stable under heat and resistant to proteolytic degradation C_LIO_LIHerbicolin A has strong solubility and stability in a model dairy system C_LIO_LIHerbicolin A indicates low cytotoxicity against epithelial cell lines C_LI Data summaryThe authors confirm all supporting data, code and protocols have been provided within the article or through supplementary data files.

Shigella OspB, a conserved type 3 effector, is a cysteine protease and peptide recombinase. Developing a protease activity-based screen, we defined and validated an OspB consensus substrate recognition motif. We found that the P1 position is aspartic acid, although cysteine is tolerated, and the P6 position an uncharged nonpolar hydrophobic residue. We demonstrate their predicted proximity to OspB active site residues within a binding groove. These findings will facilitate identification of physiological substrates of OspB and its homologs.

Crush syndrome (CS) is a serious medical condition characterized by damage to the muscle cells due to pressure and is associated with high mortality, even in patients receiving fluid therapy. We focused on adrenaline (Adr), a standard medication administered by medical teams dispatched during disasters. Adr is readily available for use in disaster scenarios owing to its inclusion in standard emergency kits. The effectiveness of Adr in the treatment of CS remains a subject of ongoing debate. This study aimed to evaluate the impact of Adr on acute complications, such as heart failure, shock, and renal failure, and explore whether its influence on inflammatory pathways is correlated with improved survival in rats with CS. The CS model involved subjecting anesthetized rats to bilateral hindlimb compression using a rubber tourniquet for 5 h. Subsequently, the rats were randomly divided into eight groups. Under continuous monitoring and recording of the arterial blood pressure, blood and tissue samples were collected for biochemical analyses at designated time points before and after reperfusion. The survival rate, vital signs, and blood gas parameters were higher in the CS group than in the sham group. They were improved in the Adr-treated group (0.01 or 0.01 mg/kg), which was not significantly different from that in the CS group, despite the improvement in shock and kidney dysfunction. In conclusion, intramuscular Adr provides immediate hemodynamic stabilization and renal protection during the early stages of CS. However, its use requires careful dose titration; low doses may promote the systemic release of lethal toxins, whereas high doses may worsen metabolic acidosis. These findings highlight the importance of combining Adr with other therapies, such as fluid resuscitation, to manage systemic toxemia inherent in CS.

One major aftermath of COVID-19 pandemic is cardiovascular consequences. SARS-CoV-2 binds to ACE2 and downregulates vasodilation. Dengue favors hypotension by weakening endothelial glycocalyx leading to plasma leakage. C1q levels, immune complexes (ICs), and proteomic profiles in serum samples from 52 COVID-19 and 19 pre-pandemic Dengue cases were studied. Unlike Dengue, COVID-19 serums showed elevated coagulation proteins promoting vaso-occlusion and peripheral artery diseases. The stress-induced chaperone and atherosclerosis marker, GRP78 (gene/ protein) was found upregulated upon SARS-CoV-2 spike expression in cardiac/ lung cell lines. Elevated GRP78 levels were also observed in serum samples from COVID-19-diagnosed individuals and subjects with myocardial infarction (MI) in post COVID-era. Surprisingly, spike antibodies (Abs) showed cross-binding to GRP78 and possibly contributed to the observed higher-level ICs in COVID-19 serums (cardiovascular embolism?). Co-localization studies showed that spike Abs (analogous to pro-atherosclerotic GRP78 auto-Abs) could directly bind to upregulated cellular GRP78 (type II hypersensitivity?). Both pathways could worsen vascular injury and atherosclerosis, leading to cardiac complications in COVID-19 cases with narrowed vessels.

Inflammatory bowel disease (IBD) is characterised by chronic pain, a debilitating symptom for which effective treatments are few and far between. IBD pathogenesis includes the prevalence of a variety of pro-inflammatory cytokines, including the Interleukin-6 (IL-6) family members Il-6 and Oncostatin M (OSM). Previous research has shown disruption of OSM signaling can modulate nociceptor sensitization and activation, however the downstream signalling pathway is unknown. When an in silico analysis of murine colonic sensory neuronal populations was undertaken for receptor expression for OSM and other factors necessary for intracellular signaling, we can find diverse expression indicative of functional signaling. We were able to observe that hyper Il-6 (Il-6 bound to the soluble Il-6 receptor) and OSM can elicit activation of a subset of murine sensory neurons by finding an increase in calcium mobilization following superfusion. This could then be attenuated by the pharmacologic inhibition of all janus kinases or interestingly, TYK2 alone. Furthermore, inhibition of transient receptor potential vanilloid 1 or transient receptor potential ankyrin 1 ion channels, which are known to be sensitized by OSM in other sensory neurons also reduced the proportion of OSM-responsive neurons. This further understanding of OSM signaling in sensory neurons creates avenues for more extensive research into the molecular mechanisms occurring as well as the potential to exploit these therapeutically to induce analgesia in a subset of neurons.

BackgroundNeuropathic pain is a major source of disability and distress with few pharmacological options for treatment. Opioid drugs can be effective, but high doses are needed, leading to unwanted effects. BMS-986122 is a positive allosteric modulator of the mu opioid receptor that potentiates acute opioid antinociception without increasing opioid-induced constipation, reward, or respiratory depression. Therefore, we asked if BMS-986122 could increase the effects of low-dose opioid analgesics in chronic neuropathic pain. MethodsWe employed the spared nerve injury and tibial neuroma models in rats and assessed the tactile hypersensitivity of the hind paw and site of neuroma, respectively. ResultsAdministration of low doses of (R)-methadone, morphine, or buprenorphine slightly reduced the tactile hypersensitivity of the hind paw the in spared nerve injury model. Pretreatment with BMS-986122 significantly enhanced the reversal of hypersensitivity, reaching the effect of high-dose gabapentin, a standard of care in neuropathic pain. Pretreatment with BMS-986122 similarly increased the anti-allodynic effects of low dose (R)-methadone on neuroma pain. A similar effect of (R)-methadone in the absence of BMS-986122 was only observed at a dose where respiratory distress was seen. ConclusionsThese findings show that allosteric modulators of the mu opioid receptor such as BMS-986122 can enhance opioid activity that could translate to a safe and effective treatment for chronic neuropathic pain.

Fv-HSP72 is a rapid cell-penetrating human heat shock protein for the treatment of traumatic organ injuries. We have shown this re-engineered protein (HSP72) is capable of crossing the blood brain barrier (BBB) of rats suffering a controlled cortical impact (CCI) and remains in brain tissue for up to 12 hours; long after clearance from the cortex of uninjured rats. Peptide sequences unique to Fv-HSP72 allow for its differential detection from endogenous HSP72. Male Sprague-Dawley rats were divided into 10 groups of n=10 with those animals receiving a CCI subjected to a unilateral cortical contusion simulating a moderate to severe brain injury using an electronically controlled pneumatic impact device. Control groups were either uninjured (Sham), injured (TBI Only), or injured and given buffer (TBI+Vehicle). Rats treated with one of three Fv-HSP72 variants were dosed at 10 or 30mg/kg 15m post-impact, then sacrificed 48 hours later. Cortical tissues were extracted from the ipsilateral and contralateral hemispheres for biomarker analysis. Here we report results of our drug inhibiting neurodegeneration based on five biomarkers (NF-L, pNF-H, pTau [T181, T231, S396]). These results were statistically significant, especially for one of the Fv-HSP72 variants, when comparing differences both between treatment groups and within groups (i.e. when comparing ipsi-vs. contralateral hemispheres). Significant inhibition of oxidative stress (3-NT) and inflammatory (IL-6) biomarkers were also observed (both p<0.0001). With similar results obtained for a blast injury model being published elsewhere, the analyses suggest Fv-HSP72 is neuroprotective following a direct impact brain injury. One sentence summaryThis study describes the effectiveness of a biologic agent, Fv-HSP72, in significantly inhibiting neuronal tissue damage in the brain when administered after a direct cortical impact.

Fecal microbiota transplantation (FMT) is an effective therapy for recurrent Clostridioides difficile infection and is increasingly explored for other dysbiosis-related disorders. However, its implementation as a regulated therapeutic strategy still requires robust donor screening, biosafety frameworks, and standardized processing workflows. Here, we describe the establishment of the first fecal microbiota biobank in the south of Brazil and evaluate the incorporation of metagenomic sequencing as a complementary layer of donor safety assessment. A structured donor selection pipeline based on international guidelines was implemented, integrating clinical screening, biochemical and serological testing, and microbiological analyses. Of 100 screened candidates, only four donors met all eligibility criteria and were included in the biobank, highlighting the stringency of the selection process. Shotgun metagenomic sequencing revealed a diverse resistome across all donors, including a shared core set of resistance-related genes alongside marked interindividual variability. Dominant antibiotic resistance genes included tetracycline-associated determinants, as well as ermF, CfxA-type {beta}-lactamases, and aminoglycoside-modifying enzymes, each linked to specific gut taxa. Notably, the relatively high abundance of tetW and ermF in Bacteroides fragilis suggests that this dominant commensal species may act as a reservoir for tetracycline and multidrug resistance determinants within the intestinal microbiota. Rather than serving as exclusion criteria, such determinants highlight the importance of integrating functional genomic profiling into donor characterization. Overall, this study provides a framework for microbiota biobank implementation and supports the use of metagenomics as a complementary strategy to improve biosafety and functional assessment in FMT.

Multipotent mesenchymal stem cells (MSCs) including bone marrow stromal cells (BMSCs) have shown analgesic efficacy in recent years. Studies suggested that the therapeutic effect of MSCs was mediated by their secreted small extracellular vesicles (sEVs) mainly exosomes. The present study evaluated the antihyperalgesic effect of BMSC-related sEVs in a mouse model of neuropathic pain involving chronic constriction injury of the infraorbital nerve (CCI-ION). Our separation protocol generated EV particles mostly sized in the range of exosomes (30-170 nm) and express exosome marker proteins CD9, CD81, and Tsg101, suggesting their endosome origin. We show that intravenous injection of BMSC-related sEVs attenuated pain hypersensitivity induced by CCI-ION as indicated by decreased mechanical hypersensitivity (von Frey test) and reduced aversion to noxious stimulation (conditioned place avoidance test). The antihyperalgesic effect of sEVs was observed in both female and male animals, and the effect was dose-dependent. sEVs from NAIVE serum-treated BMSC cultures produced short-lasting antihyperalgesia in male but not female mice, suggesting a subtle sex difference. The antihyperalgesia of sEVs from BMSC culture was blocked by the pretreatment of the culture with GM4869, the antagonist of exosome secretion, suggesting that the effect was not related to other co-isolated soluble mediators but mediated by MSC-derived exosomes. Interestingly, the prior injury condition in which sEVs were isolated favors the pain-relieving effect of sEVs. sEVs isolated from the serum of BMSC-treated animals receiving tendon ligation (TL) injury attenuated hyperalgesia for 24 h, while sEVs from the serum of BMSC-treated NAIVE animals only attenuated hyperalgesia at 3 h after injection. sEVs from the BMSC culture treated with the serum of TL rats were antihyperalgesic, but sEVs from the BMSC culture treated with the serum of naive animals were ineffective. Our results indicate that BMSC-related sEVs produced antihyperalgesia similar to that produced by BMSCs. The results suggest that the interactions between BMSCs and injury conditions are crucially important for producing efficacious sEVs/exosomes and support that the effect of sEVs could be optimized by priming BMSCs with injury-related conditions.