T cell vaccination eliminates antigen-specific T cells and prevents antigen-induced eosinophil recruitment into the tissue

Mechanism of Inflammation in Murine Eosinophilic Myocarditis Produced by Adoptive Transfer with Ovalbumin Challenge

BACKGROUND

Interleukin (IL)-5, RANTES and CC chemokine receptor 3 (CCR3) are essential for induction of eosinophil recruitment in organs, but the precise pathogenesis of eosinophilic myocarditis is still unclear. We investigated the relationships between these cytokines and receptors in the development of inflammation in murine myocarditis produced by adoptive transfer, with reference to eosinophil infiltration and signal transduction.

METHODS

The splenocytes from male donor DBA/2 mice were separated after ovalbumin (OVA) sensitization. These cells had a CD4/CD8 ratio of approximately 3.0. Cells (2.0 x 10(7)) were individually transfused to recipient adoptive male DBA/2 mice, and OVA challenge was performed serially. The heart and spleen of the recipient were analyzed to determine the kinetics of IL-5, RANTES, CCR3 and eosinophil production with simultaneous determination of Janus kinase 3 (JAK3) mRNA.

RESULTS

Approximately 85% of recipient mice developed myocarditis; 35% had recognizable cell infiltration in the left ventricular endocardium, an effect which was absent in control mice. Eosinophilic myocarditis was usually associated with animals having several degenerative changes in myocardial cells, and IL-5, RANTES and CCR3 expressions were usually present in these eosinophils (p < 0.05). CCR3 and JAK3 mRNAs were detected in the spleens and hearts of recipient animals providing histological evidence for kinetics related to eosinophil infiltration.

CONCLUSION

The murine model of adoptive transferred myocarditis is suitable for studying the mechanism of eosinophilic myocarditis. A unique pathogenesis of this disorder may be controlled by the synergism of CD4 dominancy in the donor and JAK-STAT signaling in the recipient, which may cause recruitment of eosinophils into heart lesions.

Do mouse models of allergic asthma mimic clinical disease?

Experimental mouse models of allergic asthma established almost 10 years ago offered new opportunities to study disease pathogenesis and to develop new therapeutics. These models focused on the factors governing the allergic immune response, on modeling clinical behavior of allergic asthma, and led to insights into pulmonary pathophysiology. Although mouse models rarely completely reproduce all the features of human disease, after sensitization and respiratory tract challenges with antigen, wild-type mice develop a clinical syndrome that closely resembles allergic asthma, characterized by eosinophilic lung inflammation, airway hyperresponsiveness (AHR), increased IgE, mucus hypersecretion, and eventually, airway remodeling. There are, however, differences between mouse and human physiology that threaten to limit the value of mouse models. Three examples of such differences relate to both clinical manifestations of disease and underlying pathogenesis. First, in contrast to patients who have increased methacholine-induced AHR even when they are symptom-free, mice exhibit only transient methacholine-induced AHR following allergen exposure. Second, chronic allergen exposure in patients leads to chronic allergic asthma, whereas repeated exposures in sensitized mice causes suppression of disease. Third, IgE and mast cells, in humans, mediate early- and late-phase allergic responses, though both are unnecessary for the generation of allergic asthma in mice. Taken together, these observations suggest that mouse models of allergic asthma are not exact replicas of human disease and thus, question the validity of these models. However, observations from mouse models of allergic asthma support many existing paradigms, although some novel discoveries in mice have yet to be verified in patients. This review presents an overview of the clinical aspects of disease in mouse models of allergic asthma emphasizing (1). the factors influencing the pathophysiological responses during the initiation and perpetuation of disease, (2). the utility of mouse models for studying clinical manifestations of disease, and (3). the applicability of mouse models for testing new treatments for allergic asthma.