Respiratory syncytial virus increases eosinophil extracellular traps in a murine model of asthma

BACKGROUND: Respiratory viral infections are the leading cause of asthma exacerbations. Eosinophil activation results in the formation of eosinophil extracellular traps (EETs), which release web-like structures of DNA and proteins that bind, disarm and extracellularly kill pathogens. OBJECTIVE: We investigated whether the respiratory syncytial virus (RSV) in vitro could induce EETs in bronchoalveolar lavage fluid eosinophils in a murine model of asthma. METHODS: BALB/cJ mice (6–8 weeks old) were sensitized with 2 subcutaneous injections of ovalbumin (20 μg) on days 0 and 7, followed by three intranasal challenges with ovalbumin (100 μg) on days 14, 15, and 16 of the protocol. The control group received Dulbecco's phosphate-buffered saline. Bronchoalveolar lavage fluid eosinophils of ovalbumin group or control group were stimulated with RSV (103 PFU/mL) in vitro for 3 hours. After that, culture supernatant was collected to perform the analyses proposed in this study. RESULTS: We verified an increase in extracellular DNA concentration in bronchoalveolar lavage fluid eosinophils from ovalbumin group stimulated with RSV (10³ PFU/mL) in vitro, which was confirmed by confocal microscopy. We demonstrated that most cells are negative for annexin V and propidium iodide in all groups evaluated. Also, RSV in vitro decreased interferon-ɣ in culture supernatant when compared to the ovalbumin group. CONCLUSION: In this study, we demonstrated for the first time that RSV in vitro induces EETs formation in eosinophils from asthmatic mice.

Nasal eosinophilia and eosinophil peroxidase in children and adolescents with rhinitis / 소아과

BACKGROUND: Researchers have shown that eosinophil peroxidase (EPO) is a relatively accurate marker of eosinophilia and eosinophil activity. However, its use as a marker of eosinophilic inflammation in nasal secretions is limited because the diagnostic cutoff values of EPO for use as a one-time test for allergic diseases such as allergic rhinitis have not been established. PURPOSE: To identify the correlation between nasal eosinophil count and EPO in children and adolescents with rhinitis. METHODS: We recruited patients <18 years of age with rhinitis for more than 2 weeks or more than 2 episodes a year whose nasal eosinophil and EPO were measured at a single allergy clinic. The eosinophil percentage was calculated by dividing the eosinophil count by the number of total cells under light microscopy at ×1,000 magnification. EPO and protein were measured from nasal secretions. We retrospectively analyzed the correlation between nasal eosinophils and protein-corrected EPO (EPO/protein) value. RESULTS: Of the 67 patients enrolled, 41 were male (61.2%); the mean age was 8.2±4.0 years. The median nasal eosinophil count was 1 and percentage was 1%. The median protein-corrected EPO value was 12.5 ng/μg (range, 0–31 ng/μg). There was a statistically significant correlation between eosinophil count and percentage (P<0.001). However, the eosinophil percentage and EPO did not correlate. The eosinophil count and EPO had a statistically significant correlation (P =0.01). The EPO cutoff value examined for nasal eosinophil counts of 2, 5, 10, and 20 was 17.57 ng/μg regardless of the reference count. The largest area under the curve value was obtained when the receiver operating characteristic curve was drawn using the eosinophil count of 2. CONCLUSION: Nasal eosinophil count was significantly associated with protein-corrected EPO.

Evidence for eosinophil recruitment, leukotriene B4 production and mast cell hyperplasia following Toxocara canis infection in rats

It is well known that eosinophilia is a key pathogenetic component of toxocariasis. The objective of the present study was to determine if there is an association between peritoneal and blood eosinophil influx, mast cell hyperplasia and leukotriene B4 (LTB4) production after Toxocara canis infection. Oral inoculation of 56-day-old Wistar rats (N = 5-7 per group) with 1000 embryonated eggs containing third-stage (L3) T. canis larvae led to a robust accumulation of total leukocytes in blood beginning on day 3 and peaking on day 18, mainly characterized by eosinophils and accompanied by higher serum LTB4 levels. At that time, we also noted increased eosinophil numbers in the peritoneal cavity. In addition, we observed increased peritoneal mast cell number in the peritoneal cavity, which correlated with the time course of eosinophilia during toxocariasis. We also demonstrated that mast cell hyperplasia in the intestines and lungs began soon after the T. canis larvae migrated to these compartments, reaching maximal levels on day 24, which correlated with the complete elimination of the parasite. Therefore, mast cells appear to be involved in peritoneal and blood eosinophil infiltration through an LTB4-dependent mechanism following T. canis infection in rats. Our data also demonstrate a tight association between larval migratory stages and intestinal and pulmonary mast cell hyperplasia in the toxocariasis model.

A distribuição dos eosinófilos nas diferentes fases de evolução do granuloma hepático em camundongos infectados pelo Schistosoma mansoni / Distribution of eosinophils at different stages of hepatic granuloma evolution in mice infected with Schistosoma mansoni

No presente estudo, avaliou-se a distribuição dos eosinófilos nas diferentes fases da formação do granuloma hepático de camundongos infectados pelo Schistosoma mansoni. A partir dos resultados obtidos sugerimos uma nova classificação para a evolução do granuloma hepático em camundongos montada a partir de fases descritas por outros autores. Em cada fase há um padrão diferente de distribuição dos eosinófilos. Na fase necrótico-exudativa os eosinófilos encontram-se concentrados na periferia e no centro do granuloma e na área de necrose eles são escassos; na "produtiva" os eosinófilos estão ainda distribuídos de maneira difusa por todo o granuloma; na de cura por fibrose se concentram na periferia e no centro do granuloma. Os eosinófilos estavam em contato direto com os ovos em todos os estágios de evolução dos granulomas. Conclui-se então que a dinâmica dos eosinófilos possui papel importante na formação da reação granulomatosa do hospedeiro e resolução do processo inflamatório causado pelo ovo do parasita, além de acrescentar novos dados na classificação dos granulomas hepáticos.

In the present study, the distribution of eosinophils at different stages of the formation of hepatic granuloma in mice infected with Schistosoma mansoni was evaluated. From the results obtained, we suggest a new classification for the evolution of hepatic granuloma in mice, constructed from the phases described by other authors. In each phase, there is a different pattern of eosinophil distribution. In the exudative-necrotic phase, the eosinophils are concentrated in the periphery and center of the granuloma, and are scarce in the necrotic area; in the productive phase, the eosinophils are dispersed throughout the granuloma; and in the cure due to fibrosis phase, the eosinophils are concentrated in the periphery and center of the granuloma. Eosinophils were found in direct contact with the eggs at all stages of evolution of the granuloma. It was concluded that the dynamics of eosinophils have an important role in forming the granulomatous reaction of the host and in resolving the inflammatory process caused by the parasite egg, as well as adding new data regarding hepatic granuloma classification.