Mooring Stone-Like Arg114 Pulls Diverse Bulged Peptides: First Insight into African Swine Fever Virus-Derived T Cell Epitopes Presented by Swine Major Histocompatibility Complex Class I.

African swine fever virus (ASFV) is the causative agent of African swine fever (ASF), which is a devastating pig disease threatening the global pork industry. However, currently, no commercial vaccines are available. During the pig immune response, major histocompatibility complex class I (MHC-I) molecules select viral peptide epitopes and present them to host cytotoxic T lymphocytes, thereby playing critical roles in eliminating viral infections. Here, we screened peptides derived from ASFV and determined the molecular basis of ASFV-derived peptides presented by the swine leukocyte antigen 1*0101 (SLA-1*0101). We found that peptide binding in SLA-1*0101 differs from the traditional mammalian binding patterns. Unlike the typical B and F pockets used by the common MHC-I molecule, SLA-1*0101 uses the D and F pockets as major peptide anchor pockets. Furthermore, the conformationally stable Arg114 residue located in the peptide-binding groove (PBG) was highly selective for the peptides. Arg114 draws negatively charged residues at positions P5 to P7 of the peptides, which led to multiple bulged conformations of different peptides binding to SLA-1*0101 and creating diversity for T cell receptor (TCR) docking. Thus, the solid Arg114 residue acts as a "mooring stone" and pulls the peptides into the PBG of SLA-1*0101. Notably, the T cell recognition and activation of p72-derived peptides were verified by SLA-1*0101 tetramer-based flow cytometry in peripheral blood mononuclear cells (PBMCs) of the donor pigs. These results refresh our understanding of MHC-I molecular anchor peptides and provide new insights into vaccine development for the prevention and control of ASF. IMPORTANCE The spread of African swine fever virus (ASFV) has caused enormous losses to the pork industry worldwide. Here, a series of ASFV-derived peptides were identified, which could bind to swine leukocyte antigen 1*0101 (SLA-1*0101), a prevalent SLA allele among Yorkshire pigs. The crystal structure of four ASFV-derived peptides and one foot-and-mouth disease virus (FMDV)-derived peptide complexed with SLA-1*0101 revealed an unusual peptide anchoring mode of SLA-1*0101 with D and F pockets as anchoring pockets. Negatively charged residues are preferred within the middle portion of SLA-1*0101-binding peptides. Notably, we determined an unexpected role of Arg114 of SLA-1*0101 as a "mooring stone" which pulls the peptide anchoring into the PBG in diverse "M"- or "n"-shaped conformation. Furthermore, T cells from donor pigs could activate through the recognition of ASFV-derived peptides. Our study sheds light on the uncommon presentation of ASFV peptides by swine MHC-I and benefits the development of ASF vaccines.

Treating Autoimmune Diseases by Targeting IL-23 with Gene-Silencing Pyrrole-Imidazole Polyamide.

Autoimmune diseases are a physiological state that immune responses are directed against and damage the body's own tissues. Numerous studies have demonstrated promising therapeutic effects in certain autoimmune diseases by targeting IL-23/IL-17 axis, mostly through using Abs against IL-23 or IL-17A. Pyrrole-imidazole polyamides are nuclease-resistant compounds that inhibit gene expression through binding to the minor groove of DNA. To develop a novel gene-silencing agent that targets IL-23/IL-17 axis, we designed polyamide that specifically binds to the transcription factor c-Rel-binding site located in the promoter of IL-23p19 subunit. Our study showed that this polyamide is capable of entering into nucleus with high efficiency in dendritic cells and macrophage. In addition, it prevented the binding of c-Rel to the promoter of IL-23p19 in vivo and specifically inhibited the expression of IL-23. More importantly, we demonstrated that this polyamide is therapeutically effective using both the imiquimod-induced psoriasis and experimental autoimmune uveitis mouse models. Taken together, these results indicate that pyrrole-imidazole polyamide targeting IL-23p19 could be a novel and feasible therapeutic strategy for patients with autoimmune diseases.

A selective membrane-targeting repurposed antibiotic with activity against persistent methicillin-resistant Staphylococcus aureus.

Treatment of Staphylococcus aureus infections is complicated by the development of antibiotic tolerance, a consequence of the ability of S. aureus to enter into a nongrowing, dormant state in which the organisms are referred to as persisters. We report that the clinically approved anthelmintic agent bithionol kills methicillin-resistant S. aureus (MRSA) persister cells, which correlates with its ability to disrupt the integrity of Gram-positive bacterial membranes. Critically, bithionol exhibits significant selectivity for bacterial compared with mammalian cell membranes. All-atom molecular dynamics (MD) simulations demonstrate that the selectivity of bithionol for bacterial membranes correlates with its ability to penetrate and embed in bacterial-mimic lipid bilayers, but not in cholesterol-rich mammalian-mimic lipid bilayers. In addition to causing rapid membrane permeabilization, the insertion of bithionol increases membrane fluidity. By using bithionol and nTZDpa (another membrane-active antimicrobial agent), as well as analogs of these compounds, we show that the activity of membrane-active compounds against MRSA persisters positively correlates with their ability to increase membrane fluidity, thereby establishing an accurate biophysical indicator for estimating antipersister potency. Finally, we demonstrate that, in combination with gentamicin, bithionol effectively reduces bacterial burdens in a mouse model of chronic deep-seated MRSA infection. This work highlights the potential repurposing of bithionol as an antipersister therapeutic agent.

[Short-term effectiveness of staged management in treatment of complex tibial plateau fracture with severe soft tissue injury].

Objective: To evaluate short-term effectiveness of staged management for complex tibial plateau fracture with severe soft tissue injury. Methods: A clinical data of 12 patients with complex tibial plateau fractures and severe soft tissue injuries between July 2017 and March 2021 and met the selection criteria was retrospectively analyzed. There were 7 males and 5 females with an average age of 43.1 years (range, 33-58 years). All patients were traffic accident injuries and admitted to hospital within 24 hours after injury. The tibial plateau fractures were closed fractures. According to the Schatzker classification standard, the fractures were rated as type Ⅳ in 3 cases, type Ⅴ in 4 cases, and type Ⅵ in 5 cases. According to the Tscherne classification standard, the soft tissue injuries were rated as grade Ⅱ in 4 cases and grade Ⅲ in 8 cases. The treatment of all patients was divided into 3 stages. In the first stage, emergency trans-articular fracture fixation with external fixator was performed; in the second stage, the fracture reduction and internal fixation were performed and bone cement was implanted to fill the bone defect; in the third stage, the bone cement was removed and the bone graft was performed to repair defect. All patients performed joint function exercise after operation as early as possible. Results: There was no neurological symptom after all staged managements, the incisions healed by first intention, and no complications such as incision infection or necrosis occurred. All patients were followed up 6-32 months (mean, 16.9 months). The fractures were all anatomical reduction confirmed by the X-ray films after operation. During follow-up, there was no obvious loss of reduction, loosening and rupture of internal fixator, or collapse of the articular surface. All fractures healed after 14-20 weeks (mean, 17.6 weeks). The posterior slope angle of the tibial plateau was (9.7±2.3)° and the varus angle was (3.9±1.9)° immediately after bone grafting, and were (8.5±2.9)° and (4.3±1.9)° respectively at 6 months after operation. There was no significant difference between the two time points ( t=0.658, P=0.514; t=-1.167, P=0.103). At last follow-up, the Hospital for Special Surgery (HSS) score was 85-96 (mean, 91.2), and the range of motion of knee was 110°-135° (mean, 120.9°). Conclusion: The staged management for complex tibial plateau fracture with severe soft tissue injury can obtain good short-term effectiveness, but the long-term effectiveness needs to be further followed up.

Nanomaterials applied in wound healing: Mechanisms, limitations and perspectives.

Internal and external factors cause various types of wounds on the skin. Infections, nonhealing chronic wounds, and aesthetic and functional recovery all cause challenges for clinicians. The development of nanotechnology in biomedicine has brought many new materials, methods and therapeutic targets for the treatment of wounds, which are believed to have great prospects. In this work, the nanomaterials applied in different stages to promote wound healing and systematically expounded their mechanisms were reviewed. Then, the difficulties and defects of the present research and suggested methods for improvement were pointed out. Moreover, based on the current application status of nanomaterials in wound treatment, some new ideas for subsequent studies were proposed and the feasibility of intelligent healing by real-time monitoring, precision regulation, and signal transmission between electronic signals and human nerve signals in the future were discussed. This review will provide valuable directions and spark new thoughts for researchers.

[[Chiral separation of five arylpropionic acid drugs and determination of their enantiomers in pharmaceutical preparations by reversed-phase high performance liquid chromatography with cellulose-tris-(4-methylbenzoate) stationary phase]].

Chromatographic behaviors for enantiomeric separation of arylpropionic acid drugs were systematically developed by reversed phase-high performance liquid chromatography (RP-HPLC) using cellulose-tris-(4-methylbenzoate) (CTMB) as chiral stationary phase (CSP). The effects of the composition of the mobile phase, additives and temperature on chiral separation of flurbiprofen, pranoprofen, naproxen, ibuprofen and loxoprofen were further investigated. The enantiomers had been successfully separated on CSP of CTMB by the mobile phase of methanol-0.1% (v/v) formic acid except naproxen by acetonitrile-0.1% (v/v) formic acid at 25 °C. The mechanisms of the racemic resolution for the above mentioned five drugs are discussed thermodynamically and structurally. The resolutions between respective enantiomers for arylpropionic acid drugs on CTMB had significant differences due to their chromatographic behaviors. The order of resolutions ranked pranoprofen, loxoprofen, flurbiprofen, ibuprofen and naproxen. The method established has been successfully applied to the determination of the enantiomers of the five drugs in commercial preparations under the optimized conditions. It proved that the method is simple, reliable and accurate.

[A novel retractor designed for mouse microsurgery].

OBJECTIVE: To introduce a novel retractor with magnetic fixator for mouse microsurgery. METHODS: The retractor was consisted of a magnet, a screw, two screw nuts and a hook made of dental stainless wire. The screw was connected to the magnet with magnetic force, and then was assembled to be a so-called magnetic fixator. The hook was clamped by two screw nuts on the screw, and these makes up of the retractor finally. Comparison has been done between the novel retractor and traditional retractor in the clinical application of the otocyst exposure. RESULTS: The retractor can quickly claw and retract massive tissue like muscles and vessels to the target position, thus, this properties would tend to offer a clear and expanded operative field. In addition, the height, orientation and strength of traction was all adjustable. By Comparison with tradition retractor, the operative incision can be shorten via the application of the retractor, also, it would reduce the trauma of muscles and vessels as well as the accidental rate of bleeding in the process of operation. CONCLUSIONS: The retractor can offer a expanded operative field of the mouse otocyst conveniently. It could be a simple, powerful and minimal invasive tool for mouse microsurgery.