In Vitro Affinity Maturation of Nanobodies against Mpox Virus A29 Protein Based on Computer-Aided Design.

Mpox virus (MPXV), the most pathogenic zoonotic orthopoxvirus, caused worldwide concern during the SARS-CoV-2 epidemic. Growing evidence suggests that the MPXV surface protein A29 could be a specific diagnostic marker for immunological detection. In this study, a fully synthetic phage display library was screened, revealing two nanobodies (A1 and H8) that specifically recognize A29. Subsequently, an in vitro affinity maturation strategy based on computer-aided design was proposed by building and docking the A29 and A1 three-dimensional structures. Ligand-receptor binding and molecular dynamics simulations were performed to predict binding modes and key residues. Three mutant antibodies were predicted using the platform, increasing the affinity by approximately 10-fold compared with the parental form. These results will facilitate the application of computers in antibody optimization and reduce the cost of antibody development; moreover, the predicted antibodies provide a reference for establishing an immunological response against MPXV.

HMSCs exosome-derived miR-199a-5p attenuates sulfur mustard-associated oxidative stress via the CAV1/NRF2 signalling pathway.

Sulfur mustard (SM) is a blister-producing chemical warfare agent which could lead to a cascade of systemic damage, especially severe acute lung injury. Oxidative stress is considered to be vital processes for the SM toxicity mechanism. We previously proved the therapeutic effect of exosomes derived from bone marrow mesenchymal stromal cells in promoting the repair of alveolar epithelial barrier and inhibiting apoptosis. However, the key functional components in exosomes and the underlying mechanisms have not been fully elaborated. This research shed light on the function of the key components of human umbilical cord mesenchymal stem cell-derived exosomes (HMSCs-Ex). We noted that HMSCs-Ex-derived miR-199a-5p played a vital role in reducing pneumonocyte oxidative stress and apoptosis by reducing reactive oxygen species, lipid peroxidation products and increasing the activities of antioxidant enzymes in BEAS-2B cells and mouse models after exposure to SM for 24 h. Furthermore, we demonstrated that the overexpression of miR-199a-5p in HMSCs-Ex treatment induced a further decrease of Caveolin1 and the activation of the mRNA and protein level of NRF2, HO1 and NQO1, compared with HMSCs-Ex administration. In summary, miR-199a-5p was one of the key molecules in HMSCs-Ex that attenuated SM-associated oxidative stress via regulating CAV1/NRF2 signalling pathway.

MiR-146a-5p delivered by hucMSC extracellular vesicles modulates the inflammatory response to sulfur mustard-induced acute lung injury.

BACKGROUND: Sulfur mustard (SM) is a highly toxic chemical warfare agent that has caused numerous casualties during wars and conflicts in the past century. Specific antidotes or therapeutic strategies are rare due to the complicated mechanism of toxicity, which still awaits elucidation. Clinical data show that acute lung injury (ALI) is responsible for most mortality and morbidity after SM exposure. Extracellular vesicles are natural materials that participate in intercellular communication by delivering various substances and can be modified. In this study, we aim to show that extracellular vesicles derived from human umbilical cord mesenchymal stromal cells (hucMSC-EVs) could exert therapeutic effects on SM-induced ALI, and to explain the underlying mechanism of effects. METHODS: MiR-146a-5p contained in hucMSC-EVs may be involved in the process of hucMSC-EVs modulating the inflammatory response to SM-induced ALI. We utilized miR-146a-5p delivered by extracellular vesicles and further modified hucMSCs with a miR-146a-5p mimic or inhibitor to collect miR-146a-5p-overexpressing extracellular vesicles (miR-146a-5p+-EVs) or miR-146a-5p-underexpressing extracellular vesicles (miR-146a-5p--EVs), respectively. Through in vivo and in vitro experiments, we investigated the mechanism. RESULTS: The effect of miR-146a-5p+-EVs on improving the inflammatory reaction tied to SM injury was better than that of hucMSC-EVs. We demonstrated that miR-146a-5p delivered by hucMSC-EVs targeted TRAF6 to negatively regulate inflammation in SM-induced ALI models in vitro and in vivo. CONCLUSION: In summary, miR-146a-5p delivered by hucMSC-EVs targeted TRAF6, causing hucMSC-EVs to exert anti-inflammatory effects in SM-induced ALI; thus, hucMSC-EVs treatment may be a promising clinical therapeutic after SM exposure.

Rapid detection of nerve agents in environmental and biological samples using a fluorescent probe.

Nerve agents are highly toxic chemical warfare agents that are easy to synthesize and have recently been applied many times in local wars and terrorist attacks. Fluorescent probes have been widely used in life science and medical research due to their features of short reaction time, high sensitivity and good selectivity. Herein, two fluorescent compounds, NMU-1 and NMU-2, were synthesized for the selective detection of nerve agents. NMU-1 exhibited good detection performance for nerve agents. With increasing nerve agent concentration, the fluorescence signal of NMU-1 at 498 nm gradually decreased with an excellent linear relationship. NMU-1 exhibited a low LOD (4.6 µM for DCP and 8.41 µM for soman), a rapid response (less than 3 min) and a large Stokes shift (98 nm) along with obvious color changes. Due to its high sensitivity and good selectivity, NMU-1 was successfully applied to image nerve agents in living PC12 cells. Furthermore, NMU-1 was used as a key element to develop chemical warfare agent test paper, which exhibited significant fluorescent changes under hand-held 365-nm UV light upon contact with nerve agents.

BMSC-derived exosomes ameliorate sulfur mustard-induced acute lung injury by regulating the GPRC5A-YAP axis.

Sulfur mustard (SM) is a highly toxic chemical warfare agent that causes acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS). There are no effective therapeutic treatments or antidotes available currently to counteract its toxic effects. Our previous study shows that bone marrow-derived mesenchymal stromal cells (BMSCs) could exert therapeutic effects against SM-induced lung injury. In this study, we explored the therapeutic potential of BMSC-derived exosomes (BMSC-Exs) against ALI and the underlying mechanisms. ALI was induced in mice by injection of SM (30 mg/kg, sc) at their medial and dorsal surfaces. BMSC-Exs (20 µg/kg in 200 µL PBS, iv) were injected for a 5-day period after SM exposure. We showed that BMSC-Exs administration caused a protective effect against pulmonary edema. Using a lung epithelial cell barrier model, BMSC-Exs (10, 20, 40 µg) dose-dependently inhibited SM-induced cell apoptosis and promoted the recovery of epithelial barrier function by facilitating the expression and relocalization of junction proteins (E-cadherin, claudin-1, occludin, and ZO-1). We further demonstrated that BMSC-Exs protected against apoptosis and promoted the restoration of barrier function against SM through upregulating G protein-coupled receptor family C group 5 type A (GPRC5A), a retinoic acid target gene predominately expressed in the epithelial cells of the lung. Knockdown of GPRC5A reduced the antiapoptotic and barrier regeneration abilities of BMSC-Exs and diminished their therapeutic effects in vitro and in vivo. BMSC-Exs-caused upregulation of GPRC5A promoted the expression of Bcl-2 and junction proteins via regulating the YAP pathway. In summary, BMSC-Exs treatment exerts protective effects against SM-induced ALI by promoting alveolar epithelial barrier repair and may be an alternative approach to stem cell-based therapy.

Two birds with one stone: The detection of nerve agents and AChE activity with an ICT-ESIPT-based fluorescence sensor.

Nerve agents are among the world's deadliest poisons, and the target enzyme is acetylcholinesterase (AChE). To better diagnosis nerve agent poisonings, a reliable diagnostic method for both nerve agents and AChE is desirable. Herein, we synthesized a series of fluorescent sensors for both real nerve agents and acetylcholinesterase activity detection. Among these sensors, HBQ-AE exhibited a fast response rate (within 10 s for nerve agent and 8 min for AChE), good sensitivity (the limit of detection is 6 nM and 0.2 U/mL) and a high off/on contrast. To the best of our knowledge, HBQ-AE is the first fluorescence sensor for nerve agents and AChE activity detection. The fluorescent change of HBQ-AE from nonfluorescence to blue fluorescence (nerve agent) or orange fluorescence (AChE) by excitation at 365 nm can be easily observed with the naked eye. HBQ-AE was successfully applied to image nerve agents and AChE activity in living cells. Moreover, HBQ-AE is the vital member to construct a test paper that can be employed to detect and diagnose chemical warfare agents.

[A systematic pharmacological investigation of pharmacologically active ingredients in Toujie Quwen granules for treatment of COVID-19].

OBJECTIVE: To explore the pharmacologically active ingredients in Toujie Quwen granules (TJQW) for treatment of coronavirus disease 2019 (COVID-19) in light of systemic pharmacology. METHODS: We performed database search, literature mining and drug-like index screening to identify the bioactive components in TJQW, the positive drugs for disease treatment and their therapeutic targets. The core disease target was investigated based on the cross-linking interaction of the bioactive components, positive drug and potential disease target, and the target proteins at the key nodes were analyzed by GO and KEGG analyses. Based on the therapeutic targets for COVID-19, virtual screening was conducted to screen the compounds in TJQW and construct the network cross-linking the key bioactive molecules in TJQW, key node targets of the disease, and the related biological pathways. RESULTS: We identified 159 compounds in TJQW and obtained 18 core proteins based on the cross-linking of the bioactive components, positive drugs and disease targets. The key node targets consisted of 22 targets including the latest 4 COVID-19 proteins. Virtual screening results showed that at least 14 compounds could bind with the core disease target proteins. The material basis of TJQW for COVID-19 treatment was explained in multi-pathway, multi-component and multi-target perspectives. In terms of the structural characteristics of the compounds, we screened the top 30 molecules with strong binding with the target proteins, among which flavonoids were the predominant components. CONCLUSIONS: This investigation reveals the therapeutic mechanism of TJQW for COVID-19 involving multiple components, targets and pathways from the perspective of key bioactive molecules, disease key node targets and related biological pathways. We screened 30 active precursors from TJQW, which provides reference for the clinical application and further development of TJQW.

Development of a Series of Fluorescent Probes for the Early Diagnostic Imaging of Sulfur Mustard Poisoning.

Sulfur mustard is one of the most harmful chemical warfare agents and can induce skin, eye, and lung injuries. However, it is hard for medical stuff to diagnose sulfur mustard poisoning early because of the incubation period after sulfur mustard exposure. Detecting intact sulfur mustard in vivo might be an effective approach for the early diagnosis of sulfur mustard poisoning. A series of fluorescent probes for intact sulfur mustard detection were developed in this study. All of the developed probes could react with sulfur mustard selectivity. Among these probes, SiNIR-SM exhibited an extremely good response rate and a high off/on contrast. To the best of our knowledge, SiNIR-SM is the first near-infrared fluorescent probe for the sulfur mustard detection. Both SiNIR-SM and OxSM-1 were successfully applied to image sulfur mustard in living cells. Using SiNIR-SM, we found that sulfur mustard accumulates in the mitochondria of living cells. This result could provide a new insight for the treatment of sulfur mustard injuries. We also found that SiNIR-SM is suitable for the early diagnostic imaging of sulfur mustard poisoning in SKH-1 mice via the detection of intact sulfur mustard.

An off-on fluorescent probe for the detection of mitochondria-specific protein persulfidation.

Protein persulfidation is a newly defined oxidative posttranslational modification and plays important roles in many biological processes. Detection of protein persulfidation in living systems is urgently needed to advance the study of H2S/H2Sn-based signalling and cellular redox regulation. Here, we developed a novel off-on fluorescent probe for the detection of persulfidation using a chemical sensor, HQO-SSH, in biological systems. HQO-SSH features fast reaction, good selectivity and high sensitivity. Due to the distinctive features of HQO-SSH, this probe was successfully applied to image protein persulfidation changes in pulmonary cells. We also demonstrated that the probe is suitable for imaging protein persulfidation in lung tissues. In addition, confocal imaging with this method revealed that sulfur mustard, a commonly used chemical warfare agent, decreased mitochondrial protein persulfidation in living lung cells and tissues. Due to these results, this probe holds great promise for exploring the role of protein persulfidation in a variety of pathophysiological conditions.