Staphylococcal Enterotoxin B Initiates Protein Kinase C Translocation and Eicosanoid Metabolism While Inhibiting Thrombin-Induced Aggregation in Human Platelets

Tran, Uyen; Boyle, Thomas; Shupp, Jeffrey W.; Hammamieh, Rasha; Jett, Marti

doi:10.1007/s11010-006-9134-6

Cited by 6 publications

(4 citation statements)

References 30 publications

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“…Staphylococcal enterotoxin (an exotoxin from Staph. aureus) is heat stable and can induce platelet dysfunction (Tran et al, 2006) and immunosuppression through effects on bovine T cells (Seo et al, 2007). It is a cause of foodborne disease in people, affecting the very young and the very old more seriously (Balaban and Rasooly, 2000).…”

Section: Discussionmentioning

confidence: 99%

Quality assessments of waste milk at a calf ranch

Moore

Taylor²,

Hartman

et al. 2009

Journal of Dairy Science

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Nonsaleable whole milk from dairy farms is potentially an economical, nutritious source of feed for neonatal calves but it can have serious quality problems. Many calf-rearing operations that utilize this milk have no system in place to assess or manage quality problems other than pasteurization. The purpose of this investigation was to evaluate the quality of nonsaleable whole milk from dairy farms being used to feed neonatal calves using a set of standard milk quality monitors. In this study, nonsaleable whole milk samples from 12 dairies supplying both milk and calves to one calf ranch were collected and evaluated for total solids (TS) percentage, bacterial counts, coagulation with ethanol, somatic cell counts, and pH. Milk quality was not uniform among the farms. Bacterial counts provided relatively little useful information to assess milk quality, because most samples (9/12) had very high bacteria counts. The most variable quality finding was TS percentage. Many samples were low in TS, contributing to a low TS percentage in pooled milk being fed to calves, which created a poor nutritional product delivered to them. Although there are advantages to feeding nonsaleable whole milk to preweaned calves, there can be significant disadvantages if the quality of the product is poor. Microbial quality is an important aspect of milk, but most of the samples were highly contaminated and the need for pasteurization was assumed. Simpler and more immediate monitoring methods such as milk pH, the alcohol test, and TS could be used at the ranch to make decisions on whether to use the milk. On the study ranch, a program to evaluate the TS of nonsaleable whole milk was implemented and a chart to add solids was devised for the producer so that the neonatal calves would not be underfed nutrients. Implementing these measures will help improve the health and growth of young calves.

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Section: Discussionmentioning

confidence: 99%

Quality assessments of waste milk at a calf ranch

Moore

Taylor²,

Hartman

et al. 2009

Journal of Dairy Science

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“…This enzyme, essential for platelet response, is therefore no longer found in physiological conditions and therefore cannot ensure its function. This explains why platelets incubated with SEB are incapable of ensuring correct aggregation in response to thrombin (122). …”

Section: Platelets–bacteria: Focus On Staphylococcus Aureus Infectionmentioning

confidence: 99%

Platelets and Infections â€“ Complex Interactions with Bacteria

et al. 2015

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Platelets can be considered sentinels of vascular system due to their high number in the circulation and to the range of functional immunoreceptors they express. Platelets express a wide range of potential bacterial receptors, including complement receptors, FcγRII, Toll-like receptors but also integrins conventionally described in the hemostatic response, such as GPIIb–IIIa or GPIb. Bacteria bind these receptors either directly, or indirectly via fibrinogen, fibronectin, the first complement C1q, the von Willebrand Factor, etc. The fate of platelet-bound bacteria is questioned. Several studies reported the ability of activated platelets to internalize bacteria such as Staphylococcus aureus or Porphyromonas gingivalis, though there is no clue on what happens thereafter. Are they sheltered from the immune system in the cytoplasm of platelets or are they lysed? Indeed, while the presence of phagolysosome has not been demonstrated in platelets, they contain antimicrobial peptides that were shown to be efficient on S. aureus. Besides, the fact that bacteria can bind to platelets via receptors involved in hemostasis suggests that they may induce aggregation; this has indeed been described for Streptococcus sanguinis, S. epidermidis, or C. pneumoniae. On the other hand, platelets are able to display an inflammatory response to an infectious triggering. We, and others, have shown that platelet release soluble immunomodulatory factors upon stimulation by bacterial components. Moreover, interactions between bacteria and platelets are not limited to only these two partners. Indeed, platelets are also essential for the formation of neutrophil extracellular traps by neutrophils, resulting in bacterial clearance by trapping bacteria and concentrating antibacterial factors but in enhancing thrombosis. In conclusion, the platelet–bacteria interplay is a complex game; its fine analysis is complicated by the fact that the inflammatory component adds to the aggregation response.

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“…117 Staphylococcus aureus enterotoxin B similarly inhibits platelet aggregation. 118 LTA from S. aureus has also been reported to inhibit platelet activation through platelet-activating factor (PAF) receptor and raised cyclic adenosine monophosphate (cAMP), 119 as well as to inhibit platelet aggregation, [120][121][122] but may support platelet adhesion to Staphylococcus epidermidis. 123 Additional products released by S. aureus also have opposing functions on platelet aggregation.…”

Section: Bacterial Products Affect Platelet Functionsmentioning

confidence: 99%

A Champion of Host Defense: A Generic Large-Scale Cause for Platelet Dysfunction and Depletion in Infection

Pagé

Pretorius

2020

Semin Thromb Hemost

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Thrombocytopenia is commonly associated with sepsis and infections, which in turn are characterized by a profound immune reaction to the invading pathogen. Platelets are one of the cellular entities that exert considerable immune, antibacterial, and antiviral actions, and are therefore active participants in the host response. Platelets are sensitive to surrounding inflammatory stimuli and contribute to the immune response by multiple mechanisms, including endowing the endothelium with a proinflammatory phenotype, enhancing and amplifying leukocyte recruitment and inflammation, promoting the effector functions of immune cells, and ensuring an optimal adaptive immune response. During infection, pathogens and their products influence the platelet response and can even be toxic. However, platelets are able to sense and engage bacteria and viruses to assist in their removal and destruction. Platelets greatly contribute to host defense by multiple mechanisms, including forming immune complexes and aggregates, shedding their granular content, and internalizing pathogens and subsequently being marked for removal. These processes, and the nature of platelet function in general, cause the platelet to be irreversibly consumed in the execution of its duty. An exaggerated systemic inflammatory response to infection can drive platelet dysfunction, where platelets are inappropriately activated and face immunological destruction. While thrombocytopenia may arise by condition-specific mechanisms that cause an imbalance between platelet production and removal, this review evaluates a generic large-scale mechanism for platelet depletion as a repercussion of its involvement at the nexus of responses to infection.

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Staphylococcal Enterotoxin B Initiates Protein Kinase C Translocation and Eicosanoid Metabolism While Inhibiting Thrombin-Induced Aggregation in Human Platelets

Cited by 6 publications

References 30 publications

Quality assessments of waste milk at a calf ranch

Quality assessments of waste milk at a calf ranch

Platelets and Infections â€“ Complex Interactions with Bacteria

A Champion of Host Defense: A Generic Large-Scale Cause for Platelet Dysfunction and Depletion in Infection

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