The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Xuming Deng - One of the best experts on this subject based on the ideXlab platform.
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Chalcone Attenuates Staphylococcus aureus Virulence by Targeting Sortase A and Alpha-Hemolysin.
Frontiers in microbiology, 2017Co-Authors: Bing Zhang, Xuming Deng, Xiaodi Niu, Zihao Teng, Jianfeng WangAbstract:Staphylococcus aureus (S. aureus) resistance, considered a dilemma for the clinical treatment of this bacterial infection, is becoming increasingly intractable. Novel anti-virulence strategies will undoubtedly provide a path forward in combating these resistant bacterial infections. Sortase A (SrtA), an enzyme responsible for anchoring virulence-related surface proteins, and Alpha-Hemolysin (Hla), a pore-forming cytotoxin, have aroused great scientific interest, as they have been regarded as targets for promising agents against S. aureus infection. In this study, we discovered that chalcone, a natural small compound with little anti-S. aureus activity, could significantly inhibit SrtA activity with an IC50 of 53.15 μM and Hla hemolysis activity with an IC50 of 17.63 μM using a fluorescence resonance energy transfer (FRET) assay and a hemolysis assay, respectively. In addition, chalcone was proven to reduce protein A (SpA) display in intact bacteria, binding to fibronectin, formation of biofilm and S. aureus invasion. Chalcone could down-regulate the transcriptional levels of the hla gene and the agrA gene, thus leading to a reduction in the expression of Hla and significant protection against Hla-mediated A549 cell injury; more importantly, chalcone could also reduce mortality in infected mice. Additionally, molecular dynamics simulations and mutagenesis assays were used to identify the mechanism of chalcone against SrtA, which implied that the inhibitory activity lies in the bond between chalcone and SrtA residues Val168, Ile182 and Arg197. Taken together, the in vivo and in vitro experiments suggest that chalcone is a potential novel therapeutic compound for S. aureus infection via targeting SrtA and Hla.
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Imperatorin inhibits the expression of Alpha-Hemolysin in Staphylococcus aureus strain BAA-1717 (USA300)
Antonie van Leeuwenhoek, 2016Co-Authors: Ping Ouyang, Mao Sun, Zhongqiong Yin, Gang Shu, Junjie Chen, Juchun Lin, Lv Cheng, Xuming DengAbstract:Both community-associated and hospital-acquired infections with methicillin-resistant Staphylococcus aureus (MRSA) have been increasingly reported around the world in the past 20 years. In 2006, the Centers for Disease Control and Prevention reported that 64 % of MRSA isolates were of the USA300 clonal type in infected patients in USA. The aim of our study was to estimate the in vitro effect of imperatorin on MRSA strain BAA-1717 (USA300). The effects of imperatorin on Alpha-Hemolysin (Hla) production, when strain BAA-1717 was co-cultured with sub-inhibitory concentrations of imperatorin, were analysed using susceptibility testing, hemolysis assays, western blotting and real-time PCR. Live/Dead analysis and cytotoxicity assays were employed to examine the protective effect of imperatorin against the strain BAA-1717-mediated injury of human alveolar epithelial cells (A549). The results showed that imperatorin has no anti-S. aureus activity at the tested concentrations in vitro. However, imperatorin can observably inhibit the production of Hla in culture supernatants and reduce the transcriptional levels of hla (the gene encoding Hla) and arg (the accessory gene regulator). Imperatorin prevented Hla-mediated A549 epithelial cell injury in a co-culture system. In conclusion, our results suggested that imperatorin has the potential to be developed as a new anti-virulence drug candidate for managing S. aureus infection.
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Isorhamnetin Attenuates Staphylococcus aureus-Induced Lung Cell Injury by Inhibiting Alpha-Hemolysin Expression.
Journal of microbiology and biotechnology, 2016Co-Authors: Lanxiang Jiang, Xuming Deng, Laiying Wang, Zexin Song, Lei Shi, Jianfeng WangAbstract:Staphylococcus aureus, like other gram-positive pathogens, has evolved a large repertoire of virulence factors as a powerful weapon to subvert the host immune system, among which Alpha-Hemolysin (Hla), a secreted pore-forming cytotoxin, plays a preeminent role. We observed a concentration-dependent reduction in Hla production by S. aureus in the presence of sub-inhibitory concentrations of isorhamnetin, a flavonoid from the fruits of Hippophae rhamnoides L., which has little antibacterial activity. We further evaluate the effect of isorhamnetin on the transcription of the Hla-encoding gene hla and RNAIII, an effector molecule in the agr system. Isorhamnetin significantly down-regulated RNAIII expression and subsequently inhibited hla transcription. In a co-culture of S. aureus and lung cells, topical isorhamnetin treatment protected against S. aureus-induced cell injury. Isorhamnetin may represent a leading compound for the development of anti-virulence drugs against S. aureus infections.
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phloretin derived from apple can reduce Alpha Hemolysin expression in methicillin resistant staphylococcus aureus usa300
World Journal of Microbiology & Biotechnology, 2015Co-Authors: Xuan Zhou, Shui Liu, Bing Zhang, Bowen Liu, Xuming Deng, Yan Liu, Liping PengAbstract:Methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly important because it is the most common cause of hospital-acquired infections, which have become globally epidemic. Our study specifically focused on the MRSA strain USA300, which was shown in 2014 to be responsible for the most current pandemic of highly virulent MRSA in the United States. We aimed to evaluate the in vitro effect of phloretin on USA300. Susceptibility testing, western blotting assays, hemolysis assays and real-time RT-PCR were employed to examine the in vitro effects of phloretin on Alpha-Hemolysin (Hla) production when the bacterium was co-cultured with phloretin. The protective effect of phloretin against the USA300-mediated injury of human alveolar epithelial cells (A549) was tested using the live/dead analysis and cytotoxicity assays. We showed that sub-inhibitory concentrations of phloretin have no effect on bacterial viability; however, they can markedly inhibit the production of Hla in culture supernatants and the transcriptional levels of hla (the gene encoding Hla) and agrA (the accessory gene regulator). Phloretin, at a final concentration of 16 µg/ml, could protect A549 cells from injury caused by USA300 in the co-culture system. Our study suggests that phloretin might have a potential application in the development of treatment for MRSA infections.
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Diosmetin inhibits the expression of Alpha-Hemolysin in Staphylococcus aureus
Antonie van Leeuwenhoek, 2015Co-Authors: Shui Liu, Xuan Zhou, Hong Zhang, Bing Zhang, Bowen Liu, Xuming Deng, Liping PengAbstract:Staphylococcus aureus is a significant human pathogen that causes a wide range of diseases. Alpha-Hemolysin (Hla), a pore-forming cytotoxin that is produced by most S. aureus strains, can cause tissue injury and plays a critical role in the virulence of this pathogen. In the present study, we discovered that diosmetin, a natural flavonoid that occurs primarily in citrus fruits and exhibits little anti-S. aureus activity, could diminish the production of Hla in culture supernatants in a concentration-dependent manner. The analysis of cytotoxicity in the co-culture system of S. aureus and A549 epithelial cells showed that such inhibition confers significant protection against S. aureus-mediated injury. Our results suggested that diosmetin has the potential to be a new anti-virulence drug for S. aureus infection, particularly for the targeting of Hla.
Jianfeng Wang - One of the best experts on this subject based on the ideXlab platform.
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Chalcone Attenuates Staphylococcus aureus Virulence by Targeting Sortase A and Alpha-Hemolysin.
Frontiers in microbiology, 2017Co-Authors: Bing Zhang, Xuming Deng, Xiaodi Niu, Zihao Teng, Jianfeng WangAbstract:Staphylococcus aureus (S. aureus) resistance, considered a dilemma for the clinical treatment of this bacterial infection, is becoming increasingly intractable. Novel anti-virulence strategies will undoubtedly provide a path forward in combating these resistant bacterial infections. Sortase A (SrtA), an enzyme responsible for anchoring virulence-related surface proteins, and Alpha-Hemolysin (Hla), a pore-forming cytotoxin, have aroused great scientific interest, as they have been regarded as targets for promising agents against S. aureus infection. In this study, we discovered that chalcone, a natural small compound with little anti-S. aureus activity, could significantly inhibit SrtA activity with an IC50 of 53.15 μM and Hla hemolysis activity with an IC50 of 17.63 μM using a fluorescence resonance energy transfer (FRET) assay and a hemolysis assay, respectively. In addition, chalcone was proven to reduce protein A (SpA) display in intact bacteria, binding to fibronectin, formation of biofilm and S. aureus invasion. Chalcone could down-regulate the transcriptional levels of the hla gene and the agrA gene, thus leading to a reduction in the expression of Hla and significant protection against Hla-mediated A549 cell injury; more importantly, chalcone could also reduce mortality in infected mice. Additionally, molecular dynamics simulations and mutagenesis assays were used to identify the mechanism of chalcone against SrtA, which implied that the inhibitory activity lies in the bond between chalcone and SrtA residues Val168, Ile182 and Arg197. Taken together, the in vivo and in vitro experiments suggest that chalcone is a potential novel therapeutic compound for S. aureus infection via targeting SrtA and Hla.
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Isorhamnetin Attenuates Staphylococcus aureus-Induced Lung Cell Injury by Inhibiting Alpha-Hemolysin Expression.
Journal of microbiology and biotechnology, 2016Co-Authors: Lanxiang Jiang, Xuming Deng, Laiying Wang, Zexin Song, Lei Shi, Jianfeng WangAbstract:Staphylococcus aureus, like other gram-positive pathogens, has evolved a large repertoire of virulence factors as a powerful weapon to subvert the host immune system, among which Alpha-Hemolysin (Hla), a secreted pore-forming cytotoxin, plays a preeminent role. We observed a concentration-dependent reduction in Hla production by S. aureus in the presence of sub-inhibitory concentrations of isorhamnetin, a flavonoid from the fruits of Hippophae rhamnoides L., which has little antibacterial activity. We further evaluate the effect of isorhamnetin on the transcription of the Hla-encoding gene hla and RNAIII, an effector molecule in the agr system. Isorhamnetin significantly down-regulated RNAIII expression and subsequently inhibited hla transcription. In a co-culture of S. aureus and lung cells, topical isorhamnetin treatment protected against S. aureus-induced cell injury. Isorhamnetin may represent a leading compound for the development of anti-virulence drugs against S. aureus infections.
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apigenin alleviates the symptoms of staphylococcus aureus pneumonia by inhibiting the production of Alpha Hemolysin
Fems Microbiology Letters, 2013Co-Authors: Jing Dong, Xuming Deng, Jianfeng Wang, Jiazhang Qiu, Xiaohan Dai, Yu Zhang, Xin Wang, Wei Tan, Xiaodi Niu, Shuhua ZhaoAbstract:Staphylococcus aureus is a common human pathogenic bacteria that can cause serious infections, including lethal staphylococcal pneumonia. The development of antimicrobial resistance has limited treatment options for this pathogen; consequently, novel antibiotics and strategies are urgently desired to combat these infections. In recent years, virulence factors secreted by pathogenic microorganisms have been developed as targets for drug discovery. Alpha-Hemolysin, a pore-forming cytotoxin that is secreted by most S. aureus strains, is essential for the pathogenesis of S. aureus pneumonia. In this study, we report that apigenin, a compound extracted from parsley that has no antimicrobial activity vs. S. aureus in vitro, can remarkably decrease the production of α-Hemolysin at low concentrations. When added to the A549 cells and S. aureus co-culture system, apigenin protected A549 cells from α-Hemolysin-mediated injury. Furthermore, in vivo tests indicated that apigenin alleviated injury of the lung tissue and decreased cytokine levels in the bronchoalveolar lavage fluid in the mouse model of S. aureus pneumonia.
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Apigenin alleviates the symptoms of Staphylococcus aureus pneumonia by inhibiting the production of Alpha‐Hemolysin
FEMS microbiology letters, 2012Co-Authors: Jing Dong, Jianfeng Wang, Jiazhang Qiu, Xiaohan Dai, Yu Zhang, Xin Wang, Wei Tan, Xiaodi Niu, Xuming DengAbstract:Staphylococcus aureus is a common human pathogenic bacteria that can cause serious infections, including lethal staphylococcal pneumonia. The development of antimicrobial resistance has limited treatment options for this pathogen; consequently, novel antibiotics and strategies are urgently desired to combat these infections. In recent years, virulence factors secreted by pathogenic microorganisms have been developed as targets for drug discovery. Alpha-Hemolysin, a pore-forming cytotoxin that is secreted by most S. aureus strains, is essential for the pathogenesis of S. aureus pneumonia. In this study, we report that apigenin, a compound extracted from parsley that has no antimicrobial activity vs. S. aureus in vitro, can remarkably decrease the production of α-Hemolysin at low concentrations. When added to the A549 cells and S. aureus co-culture system, apigenin protected A549 cells from α-Hemolysin-mediated injury. Furthermore, in vivo tests indicated that apigenin alleviated injury of the lung tissue and decreased cytokine levels in the bronchoalveolar lavage fluid in the mouse model of S. aureus pneumonia.
Juliane Bubeck Wardenburg - One of the best experts on this subject based on the ideXlab platform.
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Host Response Signature to Staphylococcus aureus Alpha-Hemolysin Implicates Pulmonary Th17 Response
Infection and immunity, 2012Co-Authors: Karen M. Frank, Tong Zhou, Liliana Moreno-vinasco, Brian P. Hollett, Joe G.n. Garcia, Juliane Bubeck WardenburgAbstract:ABSTRACT Staphylococcus aureus pneumonia causes significant morbidity and mortality. Alpha-Hemolysin (Hla), a pore-forming cytotoxin of S. aureus, has been identified through animal models of pneumonia as a critical virulence factor that induces lung injury. In spite of considerable molecular knowledge of how this cytotoxin injures the host, the precise host response to Hla in the context of infection remains poorly understood. We employed whole-genome expression profiling of infected lungs to define the host response to wild-type S. aureus compared with the response to an Hla-deficient isogenic mutant in experimental pneumonia. These data provide a complete expression profile at 4 and at 24 h postinfection, revealing a unique response to the toxin-expressing strain. Gene ontogeny analysis revealed significant differences in the extracellular matrix and cardiomyopathy pathways, both of which govern cellular interactions in the tissue microenvironment. Evaluation of individual transcript responses to Hla-secreting staphylococci was notable for upregulation of host cytokine and chemokine genes, including the p19 subunit of interleukin-23. Consistent with this observation, the cellular immune response to infection was characterized by a prominent Th17 response to the wild-type pathogen. These findings define specific host mRNA responses to Hla-producing S. aureus, coupling the pulmonary Th17 response to the secretion of this cytotoxin. Expression profiling to define the host response to a single virulence factor proved to be a valuable tool in identifying pathways for further investigation in S. aureus pneumonia. This approach may be broadly applicable to the study of bacterial toxins, defining host pathways that can be targeted to mitigate toxin-induced disease.
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targeting of Alpha Hemolysin by active or passive immunization decreases severity of usa300 skin infection in a mouse model
The Journal of Infectious Diseases, 2010Co-Authors: Adam D Kennedy, Juliane Bubeck Wardenburg, Donald J Gardner, Daniel Long, Adeline R Whitney, Kevin R Braughton, Olaf Schneewind, Frank R DeleoAbstract:Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are predominantly those affecting skin and soft tissues. Although progress has been made, our knowledge of the molecules that contribute to the pathogenesis of CA-MRSA skin infections is incomplete. We tested the hypothesis that Alpha-Hemolysin (Hla) contributes to the severity of USA300 skin infections in mice and determined whether vaccination against Hla reduces disease severity. Isogenic hla-negative (Deltahla) strains caused skin lesions in a mouse infection model that were significantly smaller than those caused by wild-type USA300 and Newman strains. Moreover, infection due to wild-type strains produced dermonecrotic skin lesions, whereas there was little or no dermonecrosis in mice infected with Deltahla strains. Passive immunization with Hla-specific antisera or active immunization with a nontoxigenic form of Hla significantly reduced the size of skin lesions caused by USA300 and prevented dermonecrosis. We conclude that Hla is a potential target for therapeutics or vaccines designed to moderate severe S. aureus skin infections.
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anti Alpha Hemolysin monoclonal antibodies mediate protection against staphylococcus aureus pneumonia
Infection and Immunity, 2009Co-Authors: Brook Ragle, Juliane Bubeck WardenburgAbstract:Staphylococcus aureus pneumonia is one of the most common invasive diseases caused by this human pathogen. S. aureus Alpha-Hemolysin, a pore-forming cytotoxin, is an essential virulence factor in the pathogenesis of pneumonia. Vaccine-based targeting of this toxin provides protection against lethal staphylococcal pneumonia in a murine model system, suggesting that a monoclonal antibody-based therapy may likewise prove to be efficacious for prevention and treatment of this disease. We report the generation of two distinct anti-Alpha-Hemolysin monoclonal antibodies that antagonize toxin activity, preventing human lung cell injury in vitro and protecting experimental animals against lethal S. aureus pneumonia. Each of these two monoclonal antibodies recognized an epitope within the first 50 amino acid residues of the mature toxin and blocked the formation of a stable Alpha-Hemolysin oligomer on the target cell surface. Active immunization with the first 50 amino acids of the toxin also conferred protection against S. aureus pneumonia. Together, these data reveal passive and active immunization strategies for prevention or therapy of staphylococcal pneumonia and highlight the potential role that a critical epitope may play in defining human susceptibility to this deadly disease.
Dominique Missiakas - One of the best experts on this subject based on the ideXlab platform.
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staphylococcus aureus Alpha Hemolysin impairs corneal epithelial wound healing and promotes intracellular bacterial invasion
Experimental Eye Research, 2019Co-Authors: Ilham Putra, Behnam Rabiee, Khandaker N Anwar, Sanaz Gidfar, Xiang Shen, Mehrdad Babalooee, Mahmood Ghassemi, Neda Afsharkhamseh, Saaquib R Bakhsh, Dominique MissiakasAbstract:Colonization by Staphylococcus aureus (S. aureus) has been implicated in many infectious and wound healing disorders. This study was performed to characterize the pathogenic role of S. aureus Alpha-Hemolysin (Alpha-toxin) in corneal epithelial wound healing and infectious keratitis in the setting of a corneal wound. The effect of wild-type and isogenic Hla mutant (α-Hemolysin gene deleted) S. aureus bacteria and conditioned media on corneal epithelial wound healing was tested in vitro using a scratch assay and in vivo using a murine epithelial debridement model. The invasiveness of wild-type and Hla mutant S. aureus was evaluated in vitro in human corneal epithelial cells and in vivo in a murine model of infectious keratitis following total epithelial debridement. S. aureus and its conditioned media significantly delayed epithelial wound closure both in vitro (P < 0.05) and in vivo (P < 0.05). The effect of S. aureus on wound healing was significantly diminished with the Hla mutant strain (P < 0.05). Likewise, compared to the wild-type strain, the Hla mutant strain demonstrated significantly reduced ability to invade corneal epithelial cells in vitro (P < 0.05) and infect murine corneas following total epithelial debridement in vivo (P < 0.05). In conclusion, S. aureus Alpha-Hemolysin plays a major role in the pathologic modulation of corneal epithelial wound healing and the intracellular invasion of the bacteria. Limiting colonization by S. aureus and/or blocking Alpha-Hemolysin may provide a therapeutic approach for corneal wound healing and infectious disorders.
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Staphylococcus aureus Alpha-Hemolysin impairs corneal epithelial wound healing and promotes intracellular bacterial invasion
Experimental eye research, 2019Co-Authors: Ilham Putra, Behnam Rabiee, Khandaker N Anwar, Sanaz Gidfar, Xiang Shen, Mehrdad Babalooee, Mahmood Ghassemi, Neda Afsharkhamseh, Saaquib R Bakhsh, Dominique MissiakasAbstract:Colonization by Staphylococcus aureus (S. aureus) has been implicated in many infectious and wound healing disorders. This study was performed to characterize the pathogenic role of S. aureus Alpha-Hemolysin (Alpha-toxin) in corneal epithelial wound healing and infectious keratitis in the setting of a corneal wound. The effect of wild-type and isogenic Hla mutant (α-Hemolysin gene deleted) S. aureus bacteria and conditioned media on corneal epithelial wound healing was tested in vitro using a scratch assay and in vivo using a murine epithelial debridement model. The invasiveness of wild-type and Hla mutant S. aureus was evaluated in vitro in human corneal epithelial cells and in vivo in a murine model of infectious keratitis following total epithelial debridement. S. aureus and its conditioned media significantly delayed epithelial wound closure both in vitro (P
Xiaodi Niu - One of the best experts on this subject based on the ideXlab platform.
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Chalcone Attenuates Staphylococcus aureus Virulence by Targeting Sortase A and Alpha-Hemolysin.
Frontiers in microbiology, 2017Co-Authors: Bing Zhang, Xuming Deng, Xiaodi Niu, Zihao Teng, Jianfeng WangAbstract:Staphylococcus aureus (S. aureus) resistance, considered a dilemma for the clinical treatment of this bacterial infection, is becoming increasingly intractable. Novel anti-virulence strategies will undoubtedly provide a path forward in combating these resistant bacterial infections. Sortase A (SrtA), an enzyme responsible for anchoring virulence-related surface proteins, and Alpha-Hemolysin (Hla), a pore-forming cytotoxin, have aroused great scientific interest, as they have been regarded as targets for promising agents against S. aureus infection. In this study, we discovered that chalcone, a natural small compound with little anti-S. aureus activity, could significantly inhibit SrtA activity with an IC50 of 53.15 μM and Hla hemolysis activity with an IC50 of 17.63 μM using a fluorescence resonance energy transfer (FRET) assay and a hemolysis assay, respectively. In addition, chalcone was proven to reduce protein A (SpA) display in intact bacteria, binding to fibronectin, formation of biofilm and S. aureus invasion. Chalcone could down-regulate the transcriptional levels of the hla gene and the agrA gene, thus leading to a reduction in the expression of Hla and significant protection against Hla-mediated A549 cell injury; more importantly, chalcone could also reduce mortality in infected mice. Additionally, molecular dynamics simulations and mutagenesis assays were used to identify the mechanism of chalcone against SrtA, which implied that the inhibitory activity lies in the bond between chalcone and SrtA residues Val168, Ile182 and Arg197. Taken together, the in vivo and in vitro experiments suggest that chalcone is a potential novel therapeutic compound for S. aureus infection via targeting SrtA and Hla.
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apigenin alleviates the symptoms of staphylococcus aureus pneumonia by inhibiting the production of Alpha Hemolysin
Fems Microbiology Letters, 2013Co-Authors: Jing Dong, Xuming Deng, Jianfeng Wang, Jiazhang Qiu, Xiaohan Dai, Yu Zhang, Xin Wang, Wei Tan, Xiaodi Niu, Shuhua ZhaoAbstract:Staphylococcus aureus is a common human pathogenic bacteria that can cause serious infections, including lethal staphylococcal pneumonia. The development of antimicrobial resistance has limited treatment options for this pathogen; consequently, novel antibiotics and strategies are urgently desired to combat these infections. In recent years, virulence factors secreted by pathogenic microorganisms have been developed as targets for drug discovery. Alpha-Hemolysin, a pore-forming cytotoxin that is secreted by most S. aureus strains, is essential for the pathogenesis of S. aureus pneumonia. In this study, we report that apigenin, a compound extracted from parsley that has no antimicrobial activity vs. S. aureus in vitro, can remarkably decrease the production of α-Hemolysin at low concentrations. When added to the A549 cells and S. aureus co-culture system, apigenin protected A549 cells from α-Hemolysin-mediated injury. Furthermore, in vivo tests indicated that apigenin alleviated injury of the lung tissue and decreased cytokine levels in the bronchoalveolar lavage fluid in the mouse model of S. aureus pneumonia.
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Apigenin alleviates the symptoms of Staphylococcus aureus pneumonia by inhibiting the production of Alpha‐Hemolysin
FEMS microbiology letters, 2012Co-Authors: Jing Dong, Jianfeng Wang, Jiazhang Qiu, Xiaohan Dai, Yu Zhang, Xin Wang, Wei Tan, Xiaodi Niu, Xuming DengAbstract:Staphylococcus aureus is a common human pathogenic bacteria that can cause serious infections, including lethal staphylococcal pneumonia. The development of antimicrobial resistance has limited treatment options for this pathogen; consequently, novel antibiotics and strategies are urgently desired to combat these infections. In recent years, virulence factors secreted by pathogenic microorganisms have been developed as targets for drug discovery. Alpha-Hemolysin, a pore-forming cytotoxin that is secreted by most S. aureus strains, is essential for the pathogenesis of S. aureus pneumonia. In this study, we report that apigenin, a compound extracted from parsley that has no antimicrobial activity vs. S. aureus in vitro, can remarkably decrease the production of α-Hemolysin at low concentrations. When added to the A549 cells and S. aureus co-culture system, apigenin protected A549 cells from α-Hemolysin-mediated injury. Furthermore, in vivo tests indicated that apigenin alleviated injury of the lung tissue and decreased cytokine levels in the bronchoalveolar lavage fluid in the mouse model of S. aureus pneumonia.