Transcript Group_2_Presentation - Mast Cell

Group 2: Animal models for mast cell research
Trainer: Katerina Tiligada
Introduction
In vivo animal models for Mast cell research:
1. Guinea Pig
2. Humanized Mice
3. Zebrafish
Aim: comparison of established versus new in vivo models
Background: insufficiency of mouse models due to differences between
human and mice MC distribution, mediator release and phenotype
Aim: to evaluate a combination treatment in an animal model of early
allergic reaction in the lung by using the established guinea pig model
Treatment with pyrilamine in combination with montelukast or/and
indomethacin reduced EAR
P: Pyrilamine - H1 antagonist
M: Montelukast - cysLT inhibitor
I: Indomethacin – COX inhibitor - NSAID
Summary
The sensitized guinea pig is a well accepted and validated
model for the study of pharmacological approaches related to
allergy treatment
Limitations of the study
Methodological shortcomings (e.g. no dose-response-curve, no
justification for the selection of drugs to be investigated)
Limited novel information
Background: lack of mice model which reflects human allergy response
Aim: To generate a humanized mouse strain that develops human
granulocytes and mast cells
Differentiation of myeloid and lymphoid cells in
hu-HSC NOG IL-3/GM-Tg mice
Differentiation of myeloid and lymphoid cells in
hu-HSC NOG IL-3/GM-Tg mice
Extravasation of Evans blue dye in the skin
of hu-HSC NOG IL-3/GM-Tg mice
Summary
The first human IL-3 and GM-CSF producing mice able to develop
human granulocytes and mast cells
A new model which enables the research on human cell in vivo
Limitations of the study
Lack of cell-cell interactions of the same species origin
Mast cells can differentiate depending on the (micro)environment
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Zebrafish is a robust model for studying vertebrate hematopoiesis
Presence of mast cells, basophils and eosinophils
Orthologs of toll-like receptors (TLRs) and myd88
Structural and functional similarities between zebrafish and mammalian MCs
Aim: Investigation of the FcεRI-mediated MC response upon stimulation
Release of tryptase is induced by C48/80 and A. salmonicida
while being inhibited by ketotifen
Release of tryptase is induced by anti-IgE:DNP complex
Summary
Zebrafish represents a potential new model for studying MC-mediated
responses in vivo
Limitationsof the study
Functional studies to support the preliminary findings not conducted
Inhibition of the IgE-mediated pathway not investigated
Experimental settings are not specific for zebrafish
Overall summary
• The attempts of calibration & development of suitable models are
continuous. Overall, we are slowly getting closer to (patho)physiological
relevance
• Functional and behavioral studies on MCs are being researched in few
models, each one being suitable for a limited range of research
questions/hypotheses
• No universal model is available; depending on the question to be
answered, acceptable models have to be selected
Preliminary data
Guinea pig
Humanized mice
Zebrafish
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Validated
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Group 2: Animal models for mast cell research
Trainer: Katerina Tiligada
Points following discussion
Difficulties in in vivo studies: validation protocols; different markers, triggers, agents, etc
• Need for harmonization & standardization of the essential protocols/methodologies for
validation of novel in vivo models in various species: consideration of strain, gender, age
differences/variations; visibility of negative results is essential
• In vivo drug administration: consideration of strain-related differences, ligand specificity,
ligand-directed signaling, threshold/baseline/placebo responses, dose-response curves,
selection of the appropriate control drug
• Inter/intra species cell-cell interaction and immune responses in in vivo models
(particularly concerning Tg & humanised models)
• Comparative definition of mast cell/basophil (rodent models are different from human,
including MC/basophil phenotypes & behaviour): need for a (minimal) list of
characteristics and comparison between species