Detection and Localization of IL-8 and CXCR1 in Rainbow Trout Larvae in Response to Pseudomonas aeruginosa Lipopolysaccharide.

The salmonid industry faces challenges due to the susceptibility of fish to opportunistic pathogens, particularly in early developmental stages. Understanding the immunological capacity during these stages is crucial for developing effective disease control strategies. IL-8R, a member of the G-protein-coupled receptor family, acts as a receptor for Interleukin 8 (IL-8). The binding of IL-8 to IL-8R plays a major role in the pathophysiology of a wide spectrum of inflammatory conditions. This study focused on the immune response capacity of rainbow trout (Oncorhynchus mykiss) larvae by analyzing IL-8/CXCR1 response to lipopolysaccharide (LPS) from Pseudomonas aeruginosa. Previous research demonstrated that LPS from P. aeruginosa acts as a potent immunostimulant in teleost, enhancing pro-inflammatory cytokines. The methodology included in silico analysis and the synthesis and characterization of an omCXCR1-derived epitope peptide, which was used to produce omCXCR1-specific anti98 serum in mice. The research revealed that rainbow trout larvae 19 days post-hatching (dph) exhibited pronounced immune responses post-stimulation with 1 µg/mL of LPS. This was evidenced by the upregulated protein expression of IL-8 and omCXCR1 in trout larvae 2 and 8 h after LPS challenge, as analyzed by ELISA and immunohistochemistry. Furthermore, fluorescence microscopy successfully revealed the colocalization of IL-8 and its receptor in cells from mucosal tissues after LPS challenge in larvae 19 dph. These findings underscore the efficacy of LPS immersion as a method to activate the innate immune system in trout larvae. Furthermore, we propose IL-8 and its receptor as molecular markers for evaluating immunostimulation in the early developmental stages of salmonids.

Wettability of Amino Acid-Functionalized PSMA Electrospun Fibers for the Modulated Release of Active Agents and Its Effect on Their Bioactivity.

The ideal treatment for chronic wounds is based on the use of bioactive dressings capable of releasing active agents. However, the control of the rate at which these active agents are released is still a challenge. Bioactive polymeric fiber mats of poly(styrene-co-maleic anhydride) [PSMA] functionalized with amino acids of different hydropathic indices and L-glutamine, L-phenylalanine and L-tyrosine levels allowed obtaining derivatives of the copolymers named PSMA@Gln, PSMA@Phe and PSMA@Tyr, respectively, with the aim of modulating the wettability of the mats. The bioactive characteristics of mats were obtained by the incorporation of the active agents Calendula officinalis (Cal) and silver nanoparticles (AgNPs). A higher wettability for PSMA@Gln was observed, which is in accordance with the hydropathic index value of the amino acid. However, the release of AgNPs was higher for PSMA and more controlled for functionalized PSMA (PSMAf), while the release curves of Cal did not show behavior related to the wettability of the mats due to the apolar character of the active agent. Finally, the differences in the wettability of the mats also affected their bioactivity, which was evaluated in bacterial cultures of Staphylococcus aureus ATCC 25923 and methicillin-resistant Staphylococcus aureus ATCC 33592, an NIH/3T3 fibroblast cell line and red blood cells.

Coaxial fibers of poly(styrene-co-maleic anhydride)@poly(vinyl alcohol) for wound dressing applications: Dual and sustained delivery of bioactive agents promoting fibroblast proliferation with reduced cell adherence.

The prevalence of chronic and acute wounds, as well as the complexity of their treatment represent a great challenge for health systems around the world. In this context, the development of bioactive wound dressings that release active agents to prevent infections and promote wound healing, appears as the most promising solution. In this work, we develop an antibacterial and biocompatible wound dressing material made from coaxial electrospun fibers of poly(styrene-co-maleic anhydride) and poly(vinyl alcohol) (PSMA@PVA). The coaxial configuration of the fibers consists of a shell of poly (styrene-co-maleic anhydride) containing a variable concentration of silver nanoparticles (AgNPs) 0.1-0.6 wt% as antibacterial agent, and a core of PVA containing 1 wt% allantoin as healing agent. The fibers present diameters between 0.72 and 1.7 µm. The release of Ag+ in a physiological medium was studied for 72 h, observing a burst release during the first 14 h and then a sustained and controlled release during the remaining 58 h. Allantoin release curves showed significant release only after 14 h. The meshes showed an antibacterial activity against Pseudomonas aeruginosa and Bacillus subtilis that correlates with the amount of AgNPs incorporated and the release rate of Ag+. Indeed, meshes containing 0.3 and 0.6 wt% of AgNPs showed a 99.99% inhibition against both bacteria. The adherence and cell viability of the meshes were evaluated in mouse embryonic fibroblasts NIH/3T3, observing a significant increase in cell viability after 72 h of incubation accompanied by a reduced adhesion of fibroblasts that decreased in the presence of the active agents. These results show that the material prepared here is capable of significantly promoting fibroblast cell proliferation but without strong adherence, which makes it an ideal material for wound dressings with non-adherent characteristics and with potential for wound healing.

Glass Transition in Crosslinked Nanocomposite Scaffolds of Gelatin/Chitosan/Hydroxyapatite.

The development of biopolymeric scaffolds crosslinked with nanoparticles is an emerging field. Gelatin/chitosan scaffolds are gaining interest in medical areas, e.g., bone tissue engineering, given their suitability for nano-hydroxyapatite incorporation. The glass transition temperature is a thermodynamic property of polymer scaffolds that changes with crosslinker or nanofiller concentration. Here, we report the experimental change in glass transition temperature of gelatin/chitosan scaffolds modified by hydroxyapatite nanoparticles and crosslinker concentration. Our results show synergic effects between nanoparticles and crosslinking, which leads to a non-linear behavior of the glass transition temperature. Furthermore, a theoretical model to predict glass transition is proposed. This model can be used as a mathematical tool for the design of future scaffolds used in bone tissue engineering.