Konstantin A. Sobyanin

Objectives: The study aimed to evaluate the antibacterial and wound-healing potential of the engineered lysin GRC-ML07 in a mouse model of full-thickness wounds infected with multidrug-resistant Pseudomonas aeruginosa under immunosuppression. Methods: Male BALB/c mice (22–24 g) were immunocompromised with cyclophosphamide. Three days later, full-thickness excisional wounds were created and infected with P. aeruginosa (10⁷ cells/wound). The lysin GRC-ML07 incapsulated into an alginate gel was applied topically to the wound area twice a day for four days after infection. Wound swabs for microbiological assays and scab tissues for cytokine and cellular profiling were collected on days 4 and 7. Histological samples were taken on days 4, 7, 14, and 21. Results: Lysin GRC-ML07 induced bacterial lysis accompanied by low activation of TLR2, TLR4, or TLR7/8 signaling pathways and pro-inflammatory cytokine production in vitro. Its application in vivo resulted in decreased levels of GM-CSF, IL-1β, IL-6, IL-17A, and TNF-α in the wound, accompanied by a 46% increase in neutrophil counts on day 4 compared to control and placebo (alginate gel) groups. By day 7, lysin treatment reduced bacterial load by 2 log, decreased neutrophil counts in wounds, and led a transition of the wounds to the granulation and epithelialization phase with scab desquamation. Conclusions: It was first shown that engineered lysin GRC-ML07 exhibits not only antibacterial, but pronounced pro-healing effects in immunocompromised mice, promoting resolution of inflammation and transition to the granulation/epithelialization phase.

This study investigates the therapeutic potential of a new compound, potassium 2-[2-(2-oxo-4-phenylpyrrolidin-1-yl) acetamido]ethanesulfonate (Compound I), in depression. Willner’s chronic unpredictable mild stress model of male Wistar rats was used as a depression model. The rats were randomized into four groups, including an intact group, a Compound I group, a Fluoxetine group, and a control group with saline. Behavioral tests, such as the Porsolt forced swim test, hole-board test, elevated plus maze test, and light–dark box, were used to assess the animals’ conditions. Our results demonstrated that Compound I effectively reduced the immobilization time of rats in the forced swim test, increased orientation and exploratory behavior, and decreased the latency period of going into the dark compartment compared to the control group. Hippocampal and striatal serotonin concentrations were increased in the Compound I group, and the compound also reduced the level of corticosterone in the blood plasma of rats compared to the intact animals. These results suggest that Compound I has reliable antidepressant activity, comparable to that of the reference antidepressant Fluoxetine.

This study investigates the therapeutic potential of new compound, potassium 2-[2-(2-oxo-4-phenylpyrrolidin-1-yl) acetamido]ethanesulfonate (Compound I), in depression. Willner's chronic unpredictable mild stress model of depression in 48 male Wistar rats was used a depression model. The rats were randomized into four groups, including an intact group, a Compound I group, a Fluoxetine group, and a control group receiving saline. Behavioral tests, such as the Porsolt forced swim test, hole-board test, elevated plus maze test, and light-dark box, were used to assess the animals' conditions. Our results demonstrated that Compound I effectively reduced the immobilization time of rats in the forced swim test, increased orientation and exploratory behavior, and decreased the latency period of going into the dark compartment compared to the control group. Hippocampal and striatal serotonin concentrations were increased in the Compound I group, and the compound also reduced the level of corticosterone in the blood plasma of rats compared to intact animals. These results suggest that Compound I has a reliable antidepressant activity, comparable to that of the reference antidepressant Fluoxetine.

The pathogenic Gram-positive bacterium Listeria monocytogenes has been evolving into a few phylogenetic lineages. Phylogenetically defined substitutions were described in the L. monocytogenes virulence factor InlB, which mediates active invasion into mammalian cells via interactions with surface receptors c-Met and gC1q-R. InlB internalin domain (idInlB) is central to interactions with c-Met. Here we compared activity of purified recombinant idInlB isoforms characteristic for L. monocytogenes phylogenetic lineage I and II. Size exclusion chromatography and intrinsic fluorescence were used to characterize idInlBs. Western blotting was used to study activation of c-Met-dependent MAPK- and PI3K/Akt-pathways. Solid-phase microplate binding and competition assay was used to quantify interactions with gCq1-R. Isogenic recombinant L. monocytogenes strains were used to elucidate the input of idInlB isoforms in HEp-2 cell invasion. Physicochemical parameters of idInlB isoforms were similar but not identical. Kinetics of Erk1/2 and Akt phosphorylation in response to purified idInlBs was lineage specific. Lineage I but not lineage II idInlB specifically bound gC1q-R. Antibody against gC1q-R amino acids 221–249 inhibited invasion of L. monocytogenes carrying lineage I but not lineage II idInlB. Taken together, obtained results suggested that phylogenetically defined substitutions in idInlB provide functional distinctions and might be involved in phylogenetically determined differences in virulence potential.

HGF (hepatocyte growth factor)/HGFR (HGF receptor) signaling pathway is a key pathway in liver protection and regeneration after acute toxic damage. Listeria monocytogenes toxin InlB contains a HGFR-interacting domain and is a functional analog of HGF. The aim of this work was to evaluate the hepatoprotective activity of the InlB HGFR-interacting domain. The recombinant HGFR-interacting domain InlB321/15 was purified from E. coli. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test was used to measure InlB321/15 mitogenic activity in HepG2 cells. Activation of MAPK- and PI3K/Akt-pathways was tracked with fluorescent microscopy, Western blotting, and ELISA. To evaluate hepatoprotective activity, InlB321/15 and recombinant human HGF (rhHGF) were intravenously injected at the same concentration of 2 ng·g⁻¹ to BALB/c mice 2 h before liver injury with CCl₄. InlB321/15 caused dose-dependent activation of MAPK- and PI3K/Akt-pathways and correspondent mitogenic effects. Both InlB321/15 and rhHGF improved macroscopic liver parameters (liver mass was 1.51, 1.27 and 1.15 g for the vehicle, InlB321/15 and rhHGF, respectively, p < 0.05), reduced necrosis (24.0%, 16.18% and 21.66% of the total area for the vehicle, InlB321/15 and rhHGF, respectively, p < 0.05). Obtained data suggest that InlB321/15 is a promising candidate for a tissue repair agent.

The facultative intracellular pathogenListeria monocytogenescauses a severe food-borne infection in humans and animals.L. monocytogenesinvasion factor InlB interacts with the tyrosine kinase c-Met via the N-terminal internalin domain. Previously, distinct variants of the InlB internalin domain (idInlB) have been described inL. monocytogenesfield isolates. Three variants were used to restore full-length InlB expression in theL. monocytogenesstrain EGDeΔinlB. Obtained isogenicL. monocytogenesstrains were tested in the invasion assay and intravenous, intraperitoneal, and intragastric models of infection in mice. All idInlBs were functional, restored InlB activity as an invasion factor, and improved invasion of the parental strain EGDeΔinlB into human kidney HEK23 cells. Meanwhile, distinct idInlBs provided different mortality rates and bacterial loads in internal organs. When recombinant strains were compared, the variant designated idInlB14 decreased severity of disease caused by intravenous and intraperitoneal bacterial administration, whereas this variant improved intestine colonization and stimulated intragastric infection. Obtained results demonstrated that naturally occurring idInlBs differed in their impact on severity ofL. monocytogenesinfection in mice in dependence on the infection route.