Introduction

In vivo animal models for Mast cell research:1. Guinea Pig2. Humanized Mice3. Zebrafish

Aim: comparison of established versus new in vivo models

Group 2: Animal models for mast cell researchTrainer: Katerina Tiligada

Aim: to evaluate a combination treatment in an animal model of early allergic reaction in the lung by using the established guinea pig model

Background: insufficiency of mouse models due to differences between human and mice MC distribution, mediator release and phenotype

P: Pyrilamine - H1 antagonistM: Montelukast - cysLT inhibitorI: Indomethacin – COX inhibitor - NSAID

Treatment with pyrilamine in combination with montelukast or/and indomethacin reduced EAR

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 inhu-HSC NOG IL-3/GM-Tg mice

Differentiation of myeloid and lymphoid cells inhu-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

• 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 ValidatedGuinea pig Humanized mice Zebrafish

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

Group 2: Animal models for mast cell researchTrainer: Katerina Tiligada

Points following discussion