Zhongqiong Yin's research while affiliated with Sichuan Agricultural University and other places

Novel therapeutic strategies against difficult-to-treat bacterial infections are desperately needed, and the faster and cheaper way to get them might be by repurposing existing antibiotics. Nanodelivery systems enhance the efficacy of antibiotics by guiding them to their targets, increasing the local concentration at the site of infection. While recently described nanodelivery systems are promising, they are generally not easy to adapt to different targets, and lack biocompatibility or specificity. Here, nanodelivery systems are created that source their targeting proteins from bacteriophages. Bacteriophage receptor-binding proteins and cell-wall binding domains are conjugated to nanoparticles, for the targeted delivery of rifampicin, imipenem, and ampicillin against bacterial pathogens. They show excellent specificity against their targets, and accumulate at the site of infection to deliver their antibiotic payload. Moreover, the nanodelivery systems suppress pathogen infections more effectively than 16 to 32-fold higher doses of free antibiotics. This study demonstrates that bacteriophage sourced targeting proteins are promising candidates to guide nanodelivery systems. Their specificity, availability, and biocompatibility make them great options to guide the antibiotic nanodelivery systems that are desperately needed to combat difficult-to-treat infections.

Pullorum disease (PD) is a bacterial infection caused by Salmonella pullorum (S. pullorum) that affects poultry. It is highly infectious and often fatal. Antibiotics are currently the mainstay of prophylactic and therapeutic treatments for PD, but their use can lead to the development of resistance in pathogenic bacteria and disruption of the host's intestinal flora. We added neomycin sulfate and different doses of tannic acid (TA) to the drinking water of chicks at 3 days of age and infected them with PD by intraperitoneal injection of S. pullorum at 9 days of age. We analyzed intestinal histopathological changes and the expression of immune-related genes and proteins by using the plate smear method, histological staining, real-time fluorescence quantitative PCR, ELISA kits, and 16S rRNA Analysis of intestinal flora. The results demonstrate that S. pullorum induces alterations in the immune status and impairs the functionality of the liver and intestinal barrier. We found that tannic acid significantly ameliorated S. pullorum-induced liver and intestinal damage, protected the intestinal physical and chemical barriers, restored the intestinal immune barrier function, and regulated the intestinal flora. Our results showed that TA has good anti-diarrhoeal, growth-promoting, immune-regulating, intestinal barrier-protecting and intestinal flora-balancing effects, and the best effect was achieved at an additive dose of 0.2%.

Lead and cadmium are foodborne contaminants that threaten human and animal health. It is well known that lead and cadmium produce hepatotoxicity; however, defense mechanisms against the co-toxic effects of lead and cadmium remain unknown. We investigated the mechanism of autophagy (defense mechanism) against the co-induced toxicity of lead and cadmium in rat hepatocytes (BRL-3A cells). Cultured rat liver BRL-3A cell lines were co-cultured with 10, 20, 40 μM lead and 2.5, 5, 10 μM cadmium alone and in co-culture for 12 h and exposed to 5 mM 3-Methyladenine (3-MA), 10 μM rapamycin (Rapa), and 50 nM Beclin1 siRNA to induce cellular autophagy. Our results show that treatment of BRL-3A cells with lead and cadmium significantly decreased the cell viability, increased intracellular reactive oxygen species levels, decreased mitochondrial membrane potential levels, and induced apoptosis, which are factors leading to liver injury, and cell damage was exacerbated by co-exposure to lead–cadmium. In addition, the results showed that lead and cadmium co-treatment induced autophagy. We further observed that the suppression of autophagy with 3-MA or Beclin1 siRNA promoted lead–cadmium-induced apoptosis, whereas enhancement of autophagy with Rapa suppressed lead–cadmium-induced apoptosis. These results demonstrated that co-treatment with lead and cadmium induces apoptosis in BRL-3A cells. Interestingly, the activation of autophagy provides cells with a self-protective mechanism against induced apoptosis. This study provides insights into the role of autophagy in lead–cadmium-induced apoptosis, which may be beneficial for the treatment of lead–cadmium-induced liver injury.

Novel therapeutic strategies against difficult-to-treat bacterial infections are desperately needed, and the faster and cheaper way to get them might be by repurposing existing antibiotics. Nanodelivery systems enhance the efficacy of antibiotics by guiding them to their targets, increasing the local concentration at the site of infection. While recently described nanodelivery systems are promising, they are generally not easy to adapt to different targets, and lack biocompatibility or specificity. Here, nanodelivery systems are created that source their targeting proteins from bacteriophages. Bacteriophage receptor-binding proteins and cell-wall binding domains were conjugated to nanoparticles, for the targeted delivery of rifampicin against bacterial pathogens. They showed excellent specificity against their targets, and accumulated at the site of infection to deliver their antibiotic payload. Moreover, the nanodelivery systems suppressed pathogen infections more effectively than higher doses of free antibiotic. This study demonstrates that bacteriophage sourced targeting proteins are promising candidates to guide nanodelivery systems. Their specificity, availability, and biocompatibility make them great options to guide the antibiotic nanodelivery systems that are desperately needed to combat difficult-to-treat infections.

The antibiotic resistance of Acinetobacter baumannii poses a significant threat to global public health, especially those strains that are resistant to carbapenems. Therefore, novel strategies are desperately needed for the treatment of infections caused by antibiotic-resistant A. baumannii . In this study, we report that brevicidine, a bacterial non-ribosomally produced cyclic lipopeptide, shows synergistic effects with multiple outer membrane-impermeable conventional antibiotics against A. baumannii . In particular, brevicidine, at a concentration of 1 μM, lowered the minimum inhibitory concentration of erythromycin, azithromycin, and rifampicin against A. baumannii strains by 32–128-fold. Furthermore, mechanistic studies were performed by employing erythromycin as an example of an outer membrane-impermeable conventional antibiotic, which showed the best synergistic effects with brevicidine against the tested A. baumannii strains in the present study. The results demonstrate that brevicidine disrupted the outer membrane of A. baumannii at a concentration range of 0.125–4 μM in a dose-dependent manner. This capacity of brevicidine could help the tested outer membrane-impermeable antibiotics enter A. baumannii cells and thereafter exert their antimicrobial activity. In addition, the results show that brevicidine–erythromycin combination exerted strong A. baumannii killing capacity by the enhanced inhibition of adenosine triphosphate biosynthesis and accumulation of reactive oxygen species, which are the main mechanisms causing the death of bacteria. Interestingly, brevicidine and erythromycin combination showed good therapeutic effects on A. baumannii -induced mouse peritonitis–sepsis models. These findings demonstrate that brevicidine is a promising sensitizer candidate of outer membrane-impermeable conventional antibiotics for treating A. baumannii infections in the post-antibiotic age.

Duck Tembusu virus (DTMUV) infection causes severe infectious diseases in poultry and can induce apoptosis in host cells. In this study, the mechanisms underlying DTMUV-induced apoptosis were investigated. First, DTMUV infection can activate the endoplasmic reticulum stress (ERS), and administration of the ERS inhibitor 4-phenylbutyric acid can protect cells from DTMUV-induced apoptosis, indicating that ERS is involved in DTMUV-induced apoptosis. Interestingly, suppression of either apoptosis or ERS led to impaired DTMUV proliferation. Then, we found that DTMUV activated three branches of unfolded protein response signaling [RNA-activated protein kinase-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1, and activating transcription factor 6] in duck embryo fibroblasts. Further study revealed that activation of PERK-eukaryotic initiation factor 2α up-regulated CCAAT/enhancer-binding protein homologous protein and DNA damage-inducible protein 34, which subsequently promoted apoptosis. Moreover, we found that among the DTMUV viral proteins, the nonstructural protein 3 (NS3) is the main inducer of apoptosis. On the one hand, the PERK/PKR pathway is involved in the NS3-mediated mitochondrial apoptosis pathway. On the other hand, NS3 interacts with voltage-dependent anion channel 2 (VDAC2) and inhibits the anti-apoptotic protein VDAC2 to induce apoptosis, which is accompanied by the depolarization of mitochondrial membrane potential and accumulation of intracellular reactive oxygen species. This study provides a theoretical basis for revealing the pathogenic mechanism of DTMUV infection and lays a foundation for finding antiviral targets. IMPORTANCE Duck Tembusu virus (DTMUV) is an emerging pathogenic flavivirus that replicates well in mosquito, bird, and mammalian cells. An in vivo study revealed that BALB/c mice and Kunming mice were susceptible to DTMUV after intracerebral inoculation. Moreover, there are no reports about DTMUV-related human disease, but antibodies against DTMUV and viral RNA were detected in the serum samples of duck industry workers. This information implies that DTMUV has expanded its host range and poses a threat to mammalian health. Thus, understanding the pathogenic mechanism of DTMUV is crucial for identifying potential antiviral targets. In this study, we discovered that NS3 can induce the mitochondria-mediated apoptotic pathway through the PERK/PKR pathway; it can also interact with voltage-dependent anion channel 2 to induce apoptosis. Our findings provide a theoretical basis for understanding the pathogenic mechanism of DTMUV infection and identifying potential antiviral targets and may also serve as a reference for exploring the pathogenesis of other flaviviruses.

Eriodictyol occurs naturally in a variety of fruits and vegetables, and has drawn significant attention for its potential health benefits. This study aims to look into the effects of eriodictyol on acute liver injury (ALI) induced by LPS/D-GalN and elucidate its potential molecular biological mechanisms. A total of 47 targets were predicted for the treatment of ALI with eriodictyol, and the PI3K/AKT signaling pathway played a key role in the anti-ALI processing of this drug. The in vivo experiment showed that eriodictyol can effectively reduce liver function-related biochemical indicators such as ALT, AST, and AKP. Eriodictyol can also up-regulate the levels of SOD and GSH, and inhibit the release of IL-1β, IL-6, and TNF-α. Additionally, TUNEL staining, immunohistochemistry, and RT-PCR experiments showed that eriodictyol activated the PI3K/AKT pathway and decreased the expression of Bax, caspase3, and caspase8 while increasing the expression of Bcl-2 m-RNA. Finally, molecular docking experiments and molecular dynamics simulations confirmed the stable binding between eriodictyol and PI3K, AKT molecules. This study showed that eriodictyol can activate the PI3K/AKT signaling pathway to alleviate ALI-related oxidative stress and apoptosis.

Puerarin (Pue) is a kind of isoflavone compound extracted from Pueraria lobata, which has significant antioxidant activity. Excessive use of acetaminophen (APAP) can cause oxidative stress in the liver and eventually lead to acute liver injury. The purpose of this study was to investigate the protective effect and the mechanism of puerarin on APAP‐induced liver oxidative damage. In in vitro experiments, puerarin significantly increased the cell activity of HepG2 cells, reduced the ROS accumulation, alleviated the oxidative damage and mitochondrial dysfunction. In in vivo studies, our results showed that puerarin enhanced antioxidant activity and alleviated histopathological damage. Further studies showed that puerarin decreased the expression of Keap1, promoted the nuclear migration of Nrf2, and up‐regulated the expression of GCLC, GCLM, HO‐1 and NQO1. This study demonstrated that puerarin can protect APAP‐induced liver injury via alleviating oxidative stress and mitochondrial dysfunction by affecting the nuclear migration of Nrf2 via inhibiting Keap1.