Uller L, Rydell-Tormanen K, Persson CG, Erjefalt JSAnti-Fas mAb-induced apoptosis and cytolysis of airway tissue eosinophils aggravates rather than resolves established inflammation. Respir Res 6:90

Dept. Experimental Medical Science, Lund University, BMC F10, 221 84, Lund, Sweden.
Respiratory research (Impact Factor: 3.09). 02/2005; 6(1):90. DOI: 10.1186/1465-9921-6-90
Source: PubMed


Fas receptor-mediated eosinophil apoptosis is currently forwarded as a mechanism resolving asthma-like inflammation. This view is based on observations in vitro and in airway lumen with unknown translatability to airway tissues in vivo. In fact, apoptotic eosinophils have not been detected in human diseased airway tissues whereas cytolytic eosinophils abound and constitute a major mode of degranulation of these cells. Also, Fas receptor stimulation may bypass the apoptotic pathway and directly evoke cytolysis of non-apoptotic cells. We thus hypothesized that effects of anti-Fas mAb in vivo may include both apoptosis and cytolysis of eosinophils and, hence, that established eosinophilic inflammation may not resolve by this treatment.
Weeklong daily allergen challenges of sensitized mice were followed by airway administration of anti-Fas mAb. BAL was performed and airway-pulmonary tissues were examined using light and electron microscopy. Lung tissue analysis for CC-chemokines, apoptosis, mucus production and plasma exudation (fibrinogen) were performed.
Anti-Fas mAb evoked apoptosis of 28% and cytolysis of 4% of eosinophils present in allergen-challenged airway tissues. Furthermore, a majority of the apoptotic eosinophils remained unengulfed and eventually exhibited secondary necrosis. A striking histopathology far beyond the allergic inflammation developed and included degranulated eosinophils, neutrophilia, epithelial derangement, plasma exudation, mucus-plasma plugs, and inducement of 6 CC-chemokines. In animals without eosinophilia anti-Fas evoked no inflammatory response.
An efficient inducer of eosinophil apoptosis in airway tissues in vivo, anti-Fas mAb evoked unprecedented asthma-like inflammation in mouse allergic airways. This outcome may partly reflect the ability of anti-Fas to evoke direct cytolysis of non-apoptotic eosinophils in airway tissues. Additionally, since most apoptotic tissue eosinophils progressed into the pro-inflammatory cellular fate of secondary necrosis this may also explain the aggravated inflammation. Our data indicate that Fas receptor mediated eosinophil apoptosis in airway tissues in vivo may cause severe disease exacerbation due to direct cytolysis and secondary necrosis of eosinophils.

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    • "e numbers , have pro - duced quite severe aggravation of hollow organ ( airways ) inflammation . Explaining such deleterious effects , increased accumulation of infiltrated inflammatory cells in mucosal wall and / or parenchyma , indicating impeded transepithelial elimination , has been demonstrated ( Gerwin et al . , 1999 ; Corry et al . , 2002 ; Uller et al . , 2005 ) ( Figure 2 ) . Animal model data further suggest that infectious agents can impede transepithelial egression / elimination of leuco - cytes . For example , aggravated responses to allergen chal - lenges post viral infection ( Sorkness et al . , 2007 ) could be explained by impeded transepithelial migration causing increased airway tis"
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