The combination of cloxacillin, thioridazine and tetracycline protects mice against Staphylococcus aureus peritonitis by inhibiting α-Hemolysin-induced MAPK/NF-κB/NLRP3 activation

Forsythoside A inhibited inflammatory response by inhibiting p38 JNK/MAPK/ERK and NF-κB signaling in Staphylococcus aureus pneumonia

BACKGROUND

S. aureus pneumonia, one of the most common S. aureus-induced diseases, is characterized by infectious inflammation in alveoli, distal airway, and lung interstitial. Forsythiaside A possesses anti-inflammatory, anti-infective, and other pharmacological properties in several diseases. The role of forsythiaside A remains unclear in S. aureus pneumonia.

AIM OF THE STUDY

We aimed to figure out the role of forsythiaside A in S. aureus pneumonia.

METHODS

RAW264.7 cells and C57BL6 mice were infected with S. aureus to construct S. aureus pneumonia cell model and animal model, respectively. A series of experiments including MTT, ELISA, Western blot, H&E staining and EBD staining were operated to figure out the role of forsythiaside A in S. aureus pneumonia.

RESULTS

In RAW264.7 cells, forsythiaside A did not induce cell toxicity but triggered cytokines (TNF-α, IL-6 and IL-1β) release in a dose-dependent manner. Moreover, forsythiaside A inhibited p38 JNK/MAPK/ERK and NF-κB pathways by repressing phosphorylation of p38, JNK, ERK and p65 proteins. For in vivo study, forsythiaside A improved survival rate of S. aureus pneumonia mice by alleviating lung injury. In addition, forsythiaside A protected from air-blood barrier destruction and pulmonary edema. At last, forsythiaside A inhibited neutrophils infiltration and inflammatory response in bronchoalveolar lavage fluid.

CONCLUSIONS

Forsythoside A inhibited inflammatory response by inhibiting p38 JNK/MAPK/ERK and NF-κB signaling in S. aureus pneumonia, which provided a novel insight for S. aureus pneumonia treatment.

Research progress on the interaction between intestinal flora and microRNA in pelvic inflammatory diseases

Pelvic inflammatory disease (PID) is a common infectious disease of the female upper reproductive tract, and its pathological basis is immune inflammatory response. The imbalance of gut microflora (GM) may lead to the development of inflammatory process. A large number of studies have shown that fecal microbiota transplantation, probiotics, bacteria, prebiotics, and dietary intervention may play a potential role in remodeling GM and treating diseases. MicroRNAs (miRNAs) are involved in cell development, proliferation, apoptosis and other physiological processes. In addition, they play an important role in the inflammatory process, participating in the regulation of proinflammatory and anti-inflammatory pathways. Differences in miRNA profiles may be PID diagnostic tools and serve as prognostic markers of the disease. The relationship between miRNA and GM has not been fully elucidated. Recent studies have shown the role of miRNA in the regulation and induction of GM dysbiosis. In turn, microbiota can regulate the expression of miRNA and improve the immune status of the body. Therefore, this review aims to describe the interaction between GM and miRNA in PID, and to find potential precise targeted therapy for PID.

Piceatannol and its analogues alleviate Staphylococcus aureus pathogenesis by targeting β-lactamase biofilms and α-hemolysin

β-Lactamases, biofilms and toxins pose challenges for combating S. aureus infection. Thus, identifying inhibitors that can restore bacterial sensitivity to antibiotics, destroy biofilms, and antitoxins is a promising way to develop alternative agents. In this study, we found that piceatannol (pit), along with its analogues resveratrol (ret) and pterostilbene (pts) bind with β-lactamase to inhibit its activity, and 96TYR, 58ILE and 66LYS were identified as the critical binding residues. Pit and pts reduced the ampicillin (Amp) and gentamicin (Gm) MICs against S. aureus and enhanced the bactericidal ability of Amp. Pit and its analogues inhibited the formation of S. aureus USA300. In addition, the pit analogues bound with α-hemolysin and suppressed the hemolysis activity of the bacterial culture supernatant. The mechanism analysis revealed that pit exhibited multiple potential binding modes with α-hemolysin. Pit significantly decreased the cytotoxicity and the adherence effect mediated by S. aureus and increased the survival rate of Galleria mellonella that infected with S. aureus, the pathological tissue damage of Galleria mellonella was alleviated by treatment with pit alone or in combination with Amp. Taken together, our findings identify promising compounds for the development of S. aureus infection inhibitors.

Liushen Wan alleviates the virulence and inflammation of Staphylococcus aureus via NLRP3 inflammasome and TLR2-NF-κB/p38 MAPK signaling pathways

Infectious diseases have been a major threat to health worldwide, with bacterial infections being particularly prominent. Staphylococcus aureus (S. aureus) infections are associated with the most deaths. Inhibition of virulence factor and excessive inflammation induced by S. aureus has become a potential antibiotic alternative/synergistic therapy without causing greater survival pressure to prevent the emergence of "superbugs" in the future. Liushen Wan (LSW), a traditional Chinese medicine, used for multiple bacterial infectious diseases. In this work, we researched its therapeutic effect and explored the potential mechanism of LSW aiming at S. aureus in vivo and in vitro. Minimal inhibitory concentration (MIC) assay, hemolysis assay, invasion assay, staphyloxanthin assay and evolution of resistance assay were performed to show that LSW alleviated the virulence of S. aureus without suppressing S. aureus activity, and short-term use of LSW did not make bacteria resistant to it. Biofilm inhibition assay demonstrated that LSW inhibited the formation of biofilm and destroyed mature biofilm of S. aureus. In vitro experiments using RT-qPCR, ELISA and western blot analysis indicated LSW inhibited the inflammatory reaction triggered by HK-S. aureus and S. aureus through NLRP3 inflammasome and TLR2-NF-κB/p38 MAPK pathway. Moreover, LSW alleviated lung damage induced by S. aureus. Taken together, LSW is a promising antibacterial, anti-virulence and anti-inflammatory drug, which could provide the pharmacological basis on the traditional application of LSW for diseases associated with S. aureus infection in clinical.

Sophoricoside ameliorates methicillin-resistant Staphylococcus aureus-induced acute lung injury by inhibiting Bach1/Akt pathway

BACKGROUND

The lack of effective treatments for methicillin-resistant Staphylococcus aureus (MRSA) infection, which often leads to severe acute lung injury (ALI), poses a grave threat to human life. Sophoricoside (SOP), an isoflavone glycoside abundant in the fruit of traditional Chinese herbal Sophora japonica l., showed anti-inflammatory effects against atopic dermatitis, allergic inflammation, and lipopolysaccharide-induced ALI. However, its effect and underlying mechanism on MRSA-induced ALI remain unclear.

PURPOSE

The aim of this study is to assess the protective effect of SOP in MRSA-induced ALI and elucidate its underlying molecular mechanisms.

METHODS

In vivo experiments were conducted using wild-type mice to establish MRSA-induced ALI mouse model, and the effects of SOP on ALI were evaluated by hematoxylin-eosin staining, flow cytometry, quantitative real-time polymerase chain reaction, and several biochemical indicators. Adoptive transfer experiments and BTB and CNC homology 1 knockout (Bach1-/-) mice were also utilized in this study. In vitro studies employed murine macrophages RAW264.7 cells, primary bone marrow-derived macrophages (BMDMs), and primary lung macrophages to explore the underlying molecular mechanisms.

RESULTS

The administration of SOP ameliorated MRSA-induced ALI by improving pulmonary histological damages, reducing neutrophil infiltration, suppressing oxidative stress levels, and decreasing the expression of inflammatory cytokines. In isolation experiments with ALI mouse lung macrophages and macrophage adoptive transfer experiments, SOP prevented macrophage activation, thereby reducing the production of proinflammatory cytokines. In vitro experiments demonstrated that SOP decreased the expression of inflammatory mediators in lipoteichoic acid (LTA)-stimulated RAW264.7 cells, BMDMs, and primary lung macrophages. Additionally, SOP inhibited protein kinase B (Akt) phosphorylation and treatment with MK2206-a specific inhibitor of Akt-eliminated SOP's ability to suppress LTA-stimulated macrophage inflammation. Furthermore, stimulation with LTA or MRSA up-regulated Bach1 expression; however, deletion of Bach1 abolished the inhibitory effect of SOP on p-Akt activation as well as inflammation and ALI development.

CONCLUSION

This study provides the first evidence that SOP effectively mitigates MRSA-induced ALI via suppressing macrophage activation through the inhibition of Bach1/Akt pathway. These findings highlight the potential of SOP as a novel therapeutic agent for treating MRSA-induced ALI.

Overexpression of the Mas1 gene mitigated LPS-induced inflammatory injury in mammary epithelial cells by inhibiting the NF-κB/MAPKs signaling pathways

Breast infection is the primary etiology of mastitis in dairy cows, leading to a reduction in the quality of dairy products and resulting in substantial economic losses for animal husbandry. Although antibiotic treatment can eliminate the pathogenic microorganisms that induce mastitis, it cannot repair the inflammatory damage of mammary epithelial cells and blood milk barrier. Mas1 is a G protein-coupled receptor, and its role in lipopolysaccharide (LPS) -induced inflammatory injury to mammary epithelial cells has not been studied. LPS treatment of EpH4 EV cells led to a significant downregulation of Mas1 transcript levels, which attracted our great interest, suggesting that Mas1 may be an important target for the treatment of mastitis. Therefore, this study intends to verify the role of Mas1 in the inflammatory injury of EpH4 EV cells by gene overexpression technology and gene silencing technology. The findings demonstrated that the overexpression of the Mas1 gene effectively reversed the activation of the nuclear factor-κB/mitogen-activated protein kinase (NF-κB/MAPK) signaling pathways induced by LPS, while also suppressing the upregulation of pro-inflammatory mediators. Furthermore, overexpression of the Mas1 gene reversed the downregulation of zonula occludens 1 (ZO-1), Occludin, and Claudin-3 caused by LPS, suggesting that Mas1 could promote to repair the blood-milk barrier. However, the silencing of the Mas1 gene using siRNA resulted in a contrasting effect. These results indicated that Mas1 alleviated the inflammatory injury of mammary epithelial cells induced by LPS.

In Vitro and In Vivo Antileishmanial Activity of Thioridazine

INTRODUCTION

Leishmaniasis is a neglected disease with high prevalence and incidence in tropical and subtropical areas. Existing drugs are limited due to cost, toxicity, declining efficacy and unavailability in endemic places. Drug repurposing has established as an efficient way for the discovery of drugs for a variety of diseases.

PURPOSE

The objective of the present work was testing the antileishmanial activity of thioridazine, an antipsychotic agent with demonstrated effect against other intracellular pathogens.

METHODS

The cytotoxicity for mouse peritoneal macrophages as well as the activity against Leishmania amazonensis, Leishmania mexicana and Leishmania major promastigotes and intracellular amastigotes, as well as in a mouse model of cutaneous leishmaniasis, were assessed.

RESULTS

Thioridazine inhibited the in vitro proliferation of promastigotes (50% inhibitory concentration-IC50-values in the range of 0.73 µM to 3.8 µM against L. amazonensis, L. mexicana and L. major) and intracellular amastigotes (IC50 values of 1.27 µM to 4.4 µM for the same species). In contrast, in mouse peritoneal macrophages, the 50% cytotoxic concentration was 24.0 ± 1.89 µM. Thioridazine inhibited the growth of cutaneous lesions and reduced the number of parasites in the infected tissue of mice. The dose of thioridazine that inhibited lesion development by 50% compared to controls was 23.3 ± 3.1 mg/kg and in terms of parasite load, it was 11.1 ± 0.97 mg/kg.

CONCLUSIONS

Thioridazine was effective against the promastigote and intracellular amastigote stages of three Leishmania species and in a mouse model of cutaneous leishmaniasis, supporting the potential repurposing of this drug as an antileishmanial agent.

Co-culture of Cronobacter sakazakii and Staphylococcus aureus: Explore the influence of mixed biofilm formation and regulation of Cronobacter sakazakii biofilm formation genes

Bacterial biofilm is a protective matrix composed of metabolites secreted by bacteria that envelop bacteria. By forming a biofilm, bacteria can considerably improve their environmental tolerance. In food-related processing environment, different types of microorganisms are often present in biofilms. The main contaminating strain in the powdered infant formula (PIF) processing environment, Cronobacter sakazakii and Staphylococcus aureus continues to pollute the PIF processing environment after biofilm production. This study selected Cronobacter sakazakii with a weak biofilm-forming ability as one of the test organisms. The coexistence of Cronobacter sakazakii and Staphylococcus aureus on the surface of production equipment was simulated to analyze the interaction. Biofilm formation in the co-culture group was significantly higher than the others. In-depth study of the effect of Staphylococcus aureus on the biofilm formation genes of Cronobacter sakazakii. Results show two bacteria can coexist on the surface of a metal device, forming a more compact hybrid biofilm structure. Under co-culture conditions, S. aureus increased bcsA and fliD expression in Cronobacter sakazakii, whereas decreased bcsC expression. Signaling molecules produced by Staphylococcus aureus (Autoinducer 2) significantly promoted the biofilm formation of Cronobacter sakazakii at the concentration of 0-500 ng/mL (0.099-0.177) and up-regulated the expression of bcsA, filD and flhD genes.

The combination of insulin and linezolid ameliorates Staphylococcus aureus pneumonia in individuals with diabetes via the TLR2/MAPKs/NLRP3 pathway

Diabetes mellitus (DM) complicated with Staphylococcus aureus (S. aureus) infection lacks effective treatment strategies. In this study, we found that insulin combined with linezolid has potential to deal with the thorny problem. In vitro, our drug sensitivity assay, bacterial growth curve and hemolytic tests showed that a combination of insulin and linezolid exerted good antibacterial and anti-α-hemolysin activity, CCK8 experiment, glucose content and glycogen content determination showed that the combination of insulin and linezolid increased murine macrophage survival rate and reduced the extracellular glucose level of high glucose-treated MH-S cells and intracellular glycogen level, and Western blot showed that the combination inhibited TLR2/MAPKs/NLRP3-related inflammatory pathways in MH-S cells. The results of in vivo experiments showed that the combination therapy stabilized glucose level, remained body weight, ameliorated lung injury including improving pulmonary edema and decreasing lung wet/dry weight ratio, reduced the CFUs and inflammation in the lung tissue in a mouse model of diabetes with S. aureus pneumonia, and inhibited the expression of TLR2, MAPKs and NLRP3 inflammatory pathway. Overall, the combination of insulin and linezolid as autolytic inhibitor exhibited the effects of significant antibacterial and improving glucose level in vitro and in vivo, and also has an anti-inflammation activity via the TLR2/MAPKs/NLRP3 pathway, this paves the way for new treatments for diabetes mellitus complicated with S. aureus infection.

Phenylalanine-arginine β-naphthylamide could enhance neomycin-sensitivity on Riemerella anatipestifer in vitro and in vivo

Riemerella anatipestifer is an important duck pathogen responsible for septicemia and infectious serositis, which has caused great economic losses to the duck industry. Phenylalanine-arginine β-naphthylamide (PAβN) is an efflux pump inhibitor, which mainly reduces the efflux effect by competing with antibiotics for efflux pump channels. Here, we found that R. anatipestifer strain GD2019 showed resistances to gentamicin, amikacin, kanamycin, and neomycin. Notably, PAβN could significantly reduce the Minimal inhibitory concentrations (MICs) of neomycin on the GD2019 strain. Moreover, PAβN combined with neomycin significantly decreased bacterial loads, relieved pathological injury and increase survival rate (p < 0.05) for the ducks lethally challenged by the GD2019 strain. Therefore, our results suggested, in vitro and in vivo, PAβN could reduce neomycin-resistant of R. anatipestifer. Importantly, finding of this study provide a new approach for treating antibiotic-resistant R. anatipestifer infection.

Excretory/secretory proteins inhibit host immune responses by downregulating the TLR4/NF-κB/MAPKs signaling pathway: A possible mechanism of immune evasion in parasitic nematode Haemonchus contortus

Haemonchus contortus is an important parasitic nematode of ruminants. Previous studies showed that H. contortus escape the immunity through complex mechanisms, including releasing excretory/secretory proteins (ESPs) to modulate the host immune response. However, the detailed mechanism through which H. contortus excretory/secretory proteins (HcESPs) promote immune evasion remains unknown. In the present study, we demonstrated that HcESPs inhibit the adaptive immune response of goats including downregulation of immune cell antigen presentation, upregulation of immune checkpoint molecules, activation of the STAT3/PD-L1 pathway, and activation of immunosuppressive regulatory T (Treg) cells. Furthermore, HcESPs reversed the LPS-induced upregulation of pro-inflammatory mediators in PBMCs by inhibiting the TLR4/NF-κB/MAPKs/NLRP3 signaling pathway. Our study provides a better understanding of the evasion mechanisms for H. contortus, which could be helpful in providing an alternative way to prevent the infection of this parasite.

MSC-ACE2 Ameliorates Streptococcus uberis-Induced Inflammatory Injury in Mammary Epithelial Cells by Upregulating the IL-10/STAT3/SOCS3 Pathway

In the dairy industry, Streptococcus uberis (S. uberis) is one of the most important pathogenic bacteria associated with mastitis in milk-producing cows, causing vast economic loss. To date, the only real effective method of treating and preventing streptococcal mastitis is antimicrobial therapy. In many inflammatory diseases, mesenchymal stem cells (MSCs) and angiotensin-converting enzyme 2 (ACE2) play an anti-inflammatory and anti-injurious role. Accordingly, we hypothesized that MSCs overexpressing ACE2 (MSC-ACE2) would ameliorate the inflammatory injury caused by S. uberis in mammary epithelial cells more efficiently than MSC alone. By activating the transcription 3/suppressor of cytokine signaling 3 (IL-10/STAT3/SOCS3) signaling pathway, MSC-ACE2 inhibited the NF-κB, MAPKs, apoptosis, and pyroptosis passways. Moreover, MSC-ACE2 overturned the downregulation of Occludin, Zonula occludens 1 (ZO-1), and Claudin-3 expression levels caused by S. uberis, suggesting that MSC-ACE2 promotes the repair of the blood-milk barrier. MSC-ACE2 demonstrated greater effectiveness than MSC alone, as expected. Based on these results, MSC-ACE2 effectively inhibits EpH4-Ev cell's inflammatory responses induced by S. uberis, and would be an effective therapeutic tool for treating streptococcal mastitis.