Differential Activation of Eosinophils by Bacteria Associated with Asthma

Abstract

Background: It has been suggested that there is a complex interaction between microbiota and various human diseases. Some bacteria have been reported to be involved in the inception and progression of asthma, and others in the protection against asthma. We know very little about the mechanisms by which bacteria do harm or good with regard to asthma. This study investigated whether bacteria exert differential effects on the functions of eosinophils, major effector cells in airway inflammation in asthma. Methods: Eosinophils were purified from healthy adult volunteers by Percoll density gradient centrifugation and negative immunomagnetic bead selection using anti-CD16 microbeads. Three kinds of heat-killed bacteria that have been implicated in asthma, namely Staphylococcus aureus (SA), Haemophilus influenzae (HI) and a Prevotella sp. (PS), were tested for their effects on the secretion of eosinophil-derived neurotoxin (EDN), the generation of superoxides and the production of cytokines/chemokines. Results: SA, but not HI or PS, induced significant EDN release in a dose-dependent manner. Superoxide generation was significantly enhanced by each of the bacterial species, but most strongly by SA, which induced significantly greater TNF-α production by eosinophils than either HI or PS. Conversely, interleukin 10, an anti-inflammatory cytokine, was more strongly induced by HI and PS than by SA. Conclusions: Bacteria exert differential effects on eosinophils. Based on these results, SA may be involved in the exacerbation of, and HI and PS in the inhibition of, eosinophilic inflammation in asthma.

Increased Systemic Cytokine/Chemokine Expression in Asthmatic and Non‐asthmatic Patients with Bacterial, Viral or Mixed Lung Infection

“…The cytokine/chemokine response pattern observed in this study was not related to the microbial infection type (viral, bacterial or mixed); however, bacterial infection had lower cytokine/chemokine inducer effect. We have no clear explanation for this finding; however, it has been reported that bacteria exert differential effects on eosinophils (important cell in respiratory pathology), resulting in the exacerbation or the inhibition of inflammation in lung infection . As patients with ARI were infected by different bacteria, the serum values observed in bacterial infected patients could represent the result of those responses.…”

Eosinophil-Derived Neurotoxin (EDN/RNase 2) and the Mouse Eosinophil-Associated RNases (mEars): Expanding Roles in Promoting Host Defense

“…Hosoki and colleagues [ 66 ] reported that eosinophils responded with prominent release of EDN when challenged with pathogenic bacteria, such as Clostridium difficile , in contrast to a probiotic strain, such as Bifidobacteria , which did not induce EDN release. In a subsequent study, eosinophils again released EDN selectively, notably in response to provocation with Staphylococcus aureus , but not Hemophilus or Prevotella species [ 67 ]. The way in which eosinophils differentiate between distinct bacterial strains remains to be elucidated.…”

Comparison Study of Oropharyngeal Microbiota in Case of Bronchial Asthma and Chronic Obstructive Pulmonary Disease in Different Severity Levels

“…Для большинства микроорганизмов этого рода характерна противовоспа-лительная активность в случае БА, которая заключается, в частности, в индукции синтеза интерлейкина 10 Т клет-ками [12]. Однако при тяжелой БА на фоне снижения общей представленности рода Prevotella отмечается более выраженное присутствие вида P. nanceiensis.…”