Experimental Animal Models

in Respiratory Diseases

Dr. Sibel Atış

Why are men such rat?

Experimental Animal Models in Respiratory Diseases

• Observation of functional and structural changes

• Ethiopathogenesis

• Defining of inflammatory processes

• Observation of changes in airway behaviours

• Assessment of a new molecul effects

• Development of a treatment strategy

In Respiratory Diseases;

Animal model selection

Challenge system

• Animal Model - Selection Criteria– Species– Pathogenesis– Endpoints of study– Manipulations required– Cost

• Challenge System– Delivery of Agent– Challenge Dose– Strain or Form of Agent

Species

Pathogenesis

Endpoints of study

Manipulations required

Cost

Selection Criteria:

Selection of the Species

- Sensitivity to Agent

Pathogenesis

Endpoints of study

Manipulations required

Cost

Disease Animal species

Asthma mouse, murine, guinea pig, rat, dog, cat, monkey, pig

COPD Rodents, dog, monkey, pig

Lung Cancer mouse, murine, guinea pig

Tuberculosis mouse, murine, guinea pig, rat, primates (monkey)

Bacterial/viral Pneumoni Rodents, primates

Interstitial pnömonitis/fibrosis

Rodents, rat, dog, sheep, primates

Selection of the Species

Pathogenesis

- Similarity to Human Disease Process

Endpoints of study

Manipulations required

Cost

Asthma animal models:

Antigen induced asthma animal models;

- Bronchial hyperreactivity,

- Airway eosinophilic inflamation,

- mukus hipersecretion,

- high IgE levels

Asthma animal models:

- In mouse models: additionally, active Th2 cell or dendritic cell

infiltration

Asthma animal models:

Spontanous asthma animal models:

- “t bet” Knockout mice:

Allergic asthma protocols in C57BL/6 and BALB/c mice

Immünisation Aerosol allergen

OVA 25 μg/alum i.p., 0 & 5. day1% OVA, 60 min. 2 /daily, 12&13. day

OVA 10 μg in PBS i.p., 0 & 21. day1% OVA, 60 min. 2 /daily, 28&29. day

OVA presenting dendritic cell, i.p., 0. day

1% OVA, 60 min. 2 /daily7 & 8. day

Coagule egg white implant, s.c. , 0. day

1% OVA, min. 2 /daily10&11. day

Asthma animal models:

• Occupational asthma models:

– Toluene diisocyanate

– Trimellitic anhydride (TMA), respiratory sensitization,

– 1-chloro-2,4- dinitrobenzene (DNCB), dermal

sensitization,

(Vanoirbeek JAJ, et al, J Allergy Clin Immunol 2006)

COPD animal models:

Methods:

1) Elastase or exogenous agents (chemicals/particuls) induced

2) Cigarette smoke induced

3) Genetic intervention

COPD animal models :

1) Produced by elastase or exogenous agents:

• Porcine pancreatic elastase (PPE), papain and human neutrophil elastase:panasinary emphysema

- secretory cell metaplasi,

- pulmonary function impairment,

- hipoxemia,

- right ventricular hypertrophy

COPD animal models : Egzogen agents:

repeated endotoxin: neutrophil and active macrophage

Oxidants (Nitrogen dioxide): lung damage

Repeated nitrogen dioxide: focal emphysema

Osone: fibrosis Cadmium chloride:

emphysema with primary fibrosis Coul dust and silica:

focal emphysema

COPD animal models :

2) Cigarette smoke induced COPD

• Best COPD models in animals

• Emphysema, small airway lesions and secretory cell metaplasi like as in humans

• Similarities or differences between human and animals about cytokine profile, cell proliferation and apopitosis are little known.

COPD animal models :Important point in Cigarette smoke induced COPD models

a) need to time for emphysema lesions: It chages acording to;

• Animal to animals • Exposure dose • Exposure methods (nasal or whole body)

Min. 4 mounths (in some species 12 mounths )

b) Animal species• Dog: perfect emphysema• Guina pig: vasculary changes • Rat models: do not show this changes

COPD animal models :

3) Produced by Genetic intervention:

- Knockout mice

- Transgenic mice

Lung cancer models:

Best models in mouse:

1) spontouneus models

2) produced by full carcinogens

3) produced by Cigarette smoke

4) Transgenic and Knockout models

Lung cancer models :

Morphologic, histopatholojic and molecular characteristics like as human adenocancer.

Models of nonsmall cell CA shows not metastase.

Models of small cell CA shows a lot of characteristics of human cancer (including metastase)

Lung cancer models :

The important point for clinical applications of this models:

Need to be determine of their radiosensitivity and

chemosensitivity

Tuberculosis models: Robert Koch showed that M. tuberculosis inoculation induced

lesions like human disease.

Infection has been determined with M. tuberculosis cultures in a variety of animals.

Pathological reactions: Different pattern in different animals. – Rabbit / Pulmonary Tubercles– Mouse and Guinea Pig Usually Other Forms

Tuberculosis Pathogenesis in animals

Characteristics Mouse Guina pig Rabbit Monkey

Cellulary immunity

Good Poor Good Poorf

Caseous tissue

little much medium much

Disease characteristics

granuloma

Hematogendissemination Lung Destructionwith Caseous necrosis

Disease Healed witexcept ofcavity formation,

Hemathogen dissemination Lung destructionwith Caseous necrosis

Pneumonia models:

Bacterial pneumonia models:• S. pneumoniae, • K. pneumoniae, • P. Aeruginosa induced pneumonia

Bacterial pneumonia

1) Intratracheal

2) Directly nasal route (pulmonary infection rate ~ %100)

3) Whole body: aerosol exposure to bacteria

Pneumonia models:

Viral pneumonia models:

Any animal model shows not fully clinical disease spectrum of human viral pneumonia (e.g. RSV ).

Interstitial pneumonitis/fibrosis models:

Any animal model shows not fully clinical characteristics or histopathology of human disease

Models result in general fibrosis in lung paranchima

İnterstitial pneumonitis/fibrosis models:

Pulmonary fibrosis models can be produced by several exogenous agents in several animal species.

Pulmonary fibrosis models produced by

Bleomycine has been mostly used.

Pulmonay Fibrosis – Animal Models Egzogen agent Tissue damage mechanism Animal

BleomycineProinflamatory, fibrogenic

cytocines changes the transcription pathern

mouse, rat, hamster, rabbit, dog, primates

Inorganik particuls (silica, asbest)

Tip 4 hipersensitivity reactions (with or without granuloma formation

mouse, rat, hamster, rabbit, sheep

RadiationFree radical DNA damage mouse, rat, rabbit,

dog, primates, sheep

Gen transfer (TGF-, IL-1, GM-CSF)

Specific cytocine mouse, rat

Fluorescein isothiocyanat

Not fully understood mouse,

Vanadium pentoxideNot fully understood

mouse, rat,

Haptenic antigens( TBN sulfonic acidecompounds)

Remembered cellulary immunity mouse, hamster

Selection of the Species

Pathogenesis

Endpoints of study

Manipulations required

Cost

Endpoints of study:

Survival / mortality

Pathogenesis/pathology

Clininical Observation

- Pneumonia

- Respiratory and/or other symptoms (e.g. fever)

Clinical Biochemia (e.g. inflamation mediators)

Bacteriemia / Viremia

Functional / physiological assessment

Efficiency of a new molecul/ treatment agent

Vaccine efficiency

Selection of the Species

Pathogenesis

Endpoints of study

Manipulations required

Cost

Manipulations required:

– Radiography• Larger Animal Model

– Diagnostic procedures• Bronchoscopy, BAL,pulmonary catetherisation

– Physiological Monitoring • Pulmonary function, electrophysiology

– Exposure • Inhalation (Head-Only, Nose-Only, Whole-Body)• Others (Parenteral, Oral, intraperitoneal)

Selection of the Species

Pathogenesis

Endpoints of study

Manipulations required

Cost

• Animal cost:

– Rarely Unlimited Funds– Statistical Assessment Cannot Be Compromised– Cost Comparison

• Monkeys ~ $3,500-$5,000• Rabbits ~ $90-$100• Guinea Pigs ~ $45-$55• Rats ~ $25• Mice ~ $5• Genotypically Specialized Animals - Much More

Expensive

• Challenge system:

Challenge Dose

Delivery of Agent• IM, SQ, Oral, Nasal, Aerosol

Strain or Form of Agent• Different Infectivity characteristics and serotypes

Ajanın cinsi veya formu (Kullanılan ajanlar)

• Sensitize edici ajanlar (antijenler, allerjenler v.s)

• Gazlar; ozon, NO2, SO2 vb

• Partiküller; PM, çevresel partiküller, karbon, DEP,

nanopartiküller, asbest partikülleri vs

• Sigara dumanı, ürünleri

• Diğer toksik ajanlar

• Mikrobiyal ajanlar

• Lipopolisakkarit (selektif pulmoner nötrofiliye yolaçar)

• Çeşitli kanserojenler

Route of agent delivery

Animal Exposures Units

For several animalsFor one animal

CONCLUSIONS

Solunum sistemi hastalıklarında; etyopatogenez ve yeni bir tedavi ajanının etkileri başta olmak üzere daha birçok özellik hakkında detaylı bir değerlendirme imkanı verdiği için in vivo hayvan modellerine gereksinim vardır.

Solunum sistemi hastalığı ile ilgili deneysel bir hayvan modeli oluştururken, bu modelin insanlardaki kliniğe en iyi şekilde uyarlanabilmesi açısından hayvan modelinin seçimi ve model oluşturmada seçilecek ajan oldukça önemlidir.

CONCLUSIONS

Hayvan modellerinin bir takım kısıtlılıklarının da olduğu unutulmamalıdır. Spontan olarak solunumsal hastalık gelişen

model oldukça azdır. Hayvan modelleri ister istemez solunum sistemi

hastalığının tam fenotipik özelliklerini göstermez.

Her bir hayvan türünün kendine göre zayıf ve güçlü yanları olup, araştırıcı bunlar arasından test edeceği hipotez açısından en uygun modeli seçebilmelidir.

Thank you…Thank you…Doç.Dr. Sibel ATIŞDoç.Dr. Sibel ATIŞ

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