Delta Hemolysin and Phenol-Soluble Modulins, but Not Alpha Hemolysin or Panton-Valentine Leukocidin, Induce Mast Cell Activation

Hodille, Elisabeth; Cuerq, Charlotte; Badiou, Cédric; Bienvenu, F.; Steghens, Jean‐Paul; Cartier, R; Bes, Michèle; Tristan, Anne; Pleşa, Adriana; Le, Vien T. M.; Diep, Binh An; Lina, Gérard; Dumitrescu, Oana

doi:10.3389/fcimb.2016.00180

Cited by 28 publications

(27 citation statements)

References 54 publications

(75 reference statements)

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“…The expression of the virulence-related protein delta-hemolysin (Hld) was inhibited during the resuscitation of freezing survived S. aureus . By activating the mast cells of the host, Hld causes itchiness, which leads to scratching, during S. aureus infection ( Hodille et al, 2016 ). Predictably, the accessory gene regulator A (AgrA), which controls the expressions of Hld ( Hodille et al, 2016 ), is also downregulated during resuscitation.…”

Section: Resultsmentioning

confidence: 99%

“…By activating the mast cells of the host, Hld causes itchiness, which leads to scratching, during S. aureus infection ( Hodille et al, 2016 ). Predictably, the accessory gene regulator A (AgrA), which controls the expressions of Hld ( Hodille et al, 2016 ), is also downregulated during resuscitation. This result suggests that the expression of Hld and AgrA during resuscitation after a prolonged freezing is closely associated.…”

Section: Resultsmentioning

confidence: 99%

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Comparative Proteomic and Morphological Change Analyses of Staphylococcus aureus During Resuscitation From Prolonged Freezing

Suo

Yang

Wang³

et al. 2018

Front. Microbiol.

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When frozen, Staphylococcus aureus survives in a sublethally injured state. However, S. aureus can recover at a suitable temperature, which poses a threat to food safety. To elucidate the resuscitation mechanism of freezing survived S. aureus, we used cells stored at -18°C for 90 days as controls. After resuscitating the survived cells at 37°C, the viable cell numbers were determined on tryptic soy agar with 0.6% yeast extract (TSAYE), and the non-injured-cell numbers were determined on TSAYE supplemented with 10% NaCl. The results showed that the total viable cell number did not increase within the first 3 h of resuscitation, but the osmotic regulation ability of freezing survived cells gradually recovered to the level of healthy cells, which was evidenced by the lack of difference between the two samples seen by differential cell enumeration. Scanning electron microscopy (SEM) showed that, compared to late exponential stage cells, some frozen survived cells underwent splitting and cell lysis due to deep distortion and membrane rupture. Transmission electron microscopy (TEM) showed that, in most of the frozen survived cells, the nucleoids (low electronic density area) were loose, and the cytoplasmic matrices (high electronic density area) were sparse. Additionally, a gap was seen to form between the cytoplasmic membranes and the cell walls in the frozen survived cells. The morphological changes were restored when the survived cells were resuscitated at 37°C. We also analyzed the differential proteome after resuscitation using non-labeled high-performance liquid chromatography–mass spectrometry (HPLC-MS). The results showed that, compared with freezing survived S. aureus cells, the cells resuscitated for 1 h had 45 upregulated and 73 downregulated proteins. The differentially expressed proteins were functionally categorized by gene ontology enrichment, KEGG pathway, and STRING analyses. Cell membrane synthesis-related proteins, oxidative stress resistance-related proteins, metabolism-related proteins, and virulence factors exhibited distinct expression patterns during resuscitation. These findings have implications in the understanding of the resuscitation mechanism of freezing survived S. aureus, which may facilitate the development of novel technologies for improved detection and control of foodborne pathogens in frozen food.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Comparative Proteomic and Morphological Change Analyses of Staphylococcus aureus During Resuscitation From Prolonged Freezing

Suo

Yang

Wang³

et al. 2018

Front. Microbiol.

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“…For PSM quantification, bacterial supernatants were diluted 1:5 in methanol at 4°C, and incubated for 10 min at 4°C for cold precipitation to eliminate particulate matter. After centrifugation at 10,000 × g for 5 min, PSMε and δ-toxin (variant ED99 and variant HKU10-03) were quantified using a targeted approach by HPLC—mass spectrometry (HPLC-MS) in an Agilent® system as described previously (Hodille et al, 2016 ).…”

Section: Methodsmentioning

confidence: 99%

“…The positive control (Cpos) was obtained using complete cell lysis solution (Triton X100 0.1%). As previously described, cell lysis due to toxins was expressed as percentages using the following formula:

(Hodille et al, 2016 ).…”

Section: Methodsmentioning

confidence: 99%

Understanding the Virulence of Staphylococcus pseudintermedius: A Major Role of Pore-Forming Toxins

Maali¹,

Badiou²,

Martins-Simões³

et al. 2018

Front. Cell. Infect. Microbiol.

Self Cite

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Staphylococcus pseudintermedius is responsible for severe and necrotizing infections in humans and dogs. Contrary to S. aureus, the pathophysiological mechanisms involved in this virulence are incompletely understood. We previously showed the intracellular cytotoxicity induced after internalization of S. pseudintermedius. Herein, we aimed to identify the virulence factors responsible for this cytotoxic activity. After addition of filtered S. pseudintermedius supernatants in culture cell media, MG63 cells, used as representative of non-professional phagocytic cells (NPPc), released a high level of LDH, indicating that the cytotoxicity was mainly mediated by secreted factors. Accordingly, we focused our attention on S. pseudintermedius toxins. In silico analysis found the presence of two PSMs (δ-toxin and PSMε) as well as Luk-I leukotoxin, the presence of which was confirmed by PCR in all clinical strains tested (n = 17). Recombinant Luk-I leukotoxin had no cytotoxic activity on NPPc but the ectopic expression of the CXCR2 receptor in U937 cells conferred cytotoxity to Luk-I. This is in agreement with the lack of Luk-I effect on NPPc and the previous report of Luk-I cytoxic activity on immune cells. Contrary to Luk-I, synthetic δ-toxin and PSMε had a strong cytotoxic activity on NPPc. The secretion of δ-toxin and PSMε at cytotoxic concentrations by S. pseudintermedius in culture supernatant was confirmed by HPLC-MS. In addition, the supplementation of such supernatants with human serum, known to inhibit PSM, induced a complete abolition of cytotoxicity which indicates that PSMs are the key players in the cytotoxic phenotype of NPPc. The results suggest that the severity of S. pseudintermedius infections is, at least in part, explained by a combined action of Luk-I that specifically targets immune cells expressing the CXCR2 receptor, and PSMs that disrupt cell membranes whatever the cell types. The present study strengthens the key role of PSMs in virulence of the different species belonging to Staphylococcus genus.

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“…In addition, S. aureus strains may also harbor pore-forming toxins involved in the pathophysiology of skin infections, such as Panton-Valentine Leukocidin (PVL) [11], and antibiotic-resistance genes, including methicillin resistance mediated by the mecA gene chromosomally located in the staphylococcal cassette chromosome mec (SCC mec ) [12]. …”

Section: Introductionmentioning

confidence: 99%

Molecular Epidemiology of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Ovine Dairy Chain and in Farm-Related Humans

Macori

Giacinti

Bellio

et al. 2017

Toxins

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Staphylococcus aureus is a major cause of clinical infections in humans and its enterotoxins cause foodborne disease. In the present study, we tested a total of 51 isolates of S. aureus from small-ruminant dairy farms with artisan dairy facilities, all located in Latium, Italy. The farms have a known history of a high prevalence of methicillin-resistant S. aureus (MRSA). Most of the MRSA isolates (27 of 51) belonged to spa-type t127 (43.1%), followed by t2678 (3.9%), t044 (2%), t1166 (2%), and t1773 (2%). PFGE performed on mecA positive strains identified one cluster (≥ 80% of similarity), comprising 22 MRSA. Nine of twenty-two MRSA isolates were assigned human host origin, and 13 isolates did not belong to a specific host. During the characterization study, one strain isolated from bulk tank milk samples harbored the pvl gene; the strain was not enterotoxigenic with a non-specific host according to the biotyping scheme, highlighting the possible emerging risk of transmission of bacterial virulence factors by foods, the environment, and foodhandlers. These findings stress the importance of hygienic measures at all processing steps of the food production chain and underline that monitoring for the presence of MRSA throughout the food chain is essential for public health.

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Delta Hemolysin and Phenol-Soluble Modulins, but Not Alpha Hemolysin or Panton-Valentine Leukocidin, Induce Mast Cell Activation

Cited by 28 publications

References 54 publications

Comparative Proteomic and Morphological Change Analyses of Staphylococcus aureus During Resuscitation From Prolonged Freezing

Comparative Proteomic and Morphological Change Analyses of Staphylococcus aureus During Resuscitation From Prolonged Freezing

Understanding the Virulence of Staphylococcus pseudintermedius: A Major Role of Pore-Forming Toxins

Molecular Epidemiology of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Ovine Dairy Chain and in Farm-Related Humans

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