Eosinophils

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Eosinophils DiseaseCurrent Concepts  
Gerald J. Gleich M.D. Professor of Dermatology
Medicine University of Utah Salt Lake City, UT
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Eosinophils Disease

• The seasons of the eosinophil
• Present concepts
• Anti-IL-5 treatment

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Erhlich Eosinophil Function

• Ehrlich eosinophil granules storage depots the
  stored substance discharged
• But the functions of the cell the stored
  substance unknown

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Association with Asthma Helminths

• 1889 Gollasch association between eosinophilia
  asthma
• 1898 Brown association between trichinosis
  eosinophilia

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Association with Anaphylaxis

• 1912 Schlecht Schwenker association between
  lung eosinophilia anaphylaxis
• This finding focused attention on the notion that
  eosinophils modify/neutralize mediators of
  anaphylaxis

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Association with Anaphylaxis

• 1975 Goetzl et al eosinophils neutralize
  histamine (via histaminase) SRS-A (by
  arylsulfatase). Thus, eosinophils might dampen
  the activity of mast cell products.
• A test of this hypothesis (by ablating
  eosinophils in guinea pigs with an
  anti-eosinophil serum) showed that allergic
  reactions were comparably active in the presence
  and absence of the eosinophil.

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Eosinophils Disease

• The seasons of the eosinophil
• Present concepts
• Anti-IL-5 treatment

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Eosinophils DiseasePresent Concepts

• Eosinophil products
• Observations on granule proteins
• Eosinophils asthma

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Crystalline core
Eosinophil granule
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Chromatography of Eosinophil Granule Proteins on
Sephadex G-50
Granules solubilized in 100 mM HCl, column
equilibrated with pH 4.3 acetate buffer
containing 150 mM NaCl
EPO
MBP1
EDN
ECP
MBP2
From Plager D et al, J Biol Chem 1999 27414464
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Eosinophil Structure
EM of Eosinophil and Eosinophil Granule
Eosinophil with characteristic cytoplasmic
granules
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Secretory Products of Eosinophils
Granule-derived proteins
Lipid mediators
Leukotriene C4/D4
Platelet activating factor
5-HETE
MBP homolog(MBP2)
5,15- and 8,15-diHETE
Prostaglandin E
, E
2
1
Reactive oxygen intermediates
Thromboxane B2
O
-
2
H
O
2
2
Hydroxyl radicals
Singlet oxygen
Enzymes
Antigen presentation
Collagenase 92 kDa Gelatinase (MMP-9) EPO-dependen
t brominating oxidants
Cytokines
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Numerous Cytokines And Growth Factors Are
Produced by Eosinophils
IL-1ß IL-2 IL-3 IL-4 IL-5 IL-6 IL-8 IL-10 IL-11
IL-12 IL-13 IL-16 RANTES Eotaxin MIP-1?
TGF-? TGF-?1 PDGF
GM-CSF TNF-? SCF
NGF BDGF NT-3
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Eosinophils DiseasePresent Concepts

• Eosinophil products
• Observations on granule proteins
• Eosinophils asthma

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Eosinophils Tissue DamagePresent concepts

• Granule proteins
• are cationic toxins able to disrupt membranes
• are toxic to helminths bacteria
• are toxic to cells from numerous organs,
  including bronchial epithelium, keratinocytes,
  pneumocytes, gut epithelium

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Eosinophils Tissue DamagePresent concepts

• Toxic concentrations of granule proteins are
  present at sites of tissue injury.
• These diseases include asthma, helminth
  infections, eye diseases, GI diseases, heart
  diseases, skin diseases and malignancies.

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Eosinophils Tissue DamagePresent concepts

• Eosinophil granule proteins activate cells,
  including eosinophils themselves, basophils,
  neutrophils, mast cells bronchial epithelial
  cells.
• In turn, many of these activated cells produce
  new molecules (such that it is a challenge to
  know precisely who is doing what to whom when
  intact eosinophils released granule proteins
  are present).

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Eosinophils Tissue DamagePresent concepts

• Granule proteins interact with other molecules,
  such as M2 muscarinic receptors, clotting and
  complement components, altering their functions.
• Granule proteins with RNase activity neutralize
  viruses, and this antiviral activity is
  critically dependent on possession of RNase
  activity.

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Eosinophils Tissue DamagePresent
conceptsGranule proteins summary

• Many aspects of eosinophil function can be
  explained by the activities of the granule
  proteins.
• Importantly, granule proteins are deposited in
  tissues in the virtual absence of intact
  eosinophils (indicating the need to test for
  their presence in certain cases).

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Early sclerosing mediastinitis (top) Section
stained with antibody to MBP
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Sclerosing cholangitis (top) Section stained
with antibody to MBP
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Eosinophilic fasciitis in a patient with the
eosinophilia-myalgia syndrome (top) Section
stained with antibody to MBP
(bottom) Section counterstained with H E X400
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Eosinophils DiseasePresent Concepts

• Eosinophil products
• Observations on granule proteins
• Eosinophils asthma

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In the complete absence of eosinophils,
ovalbumin sensitization/aerosol
challenge-induced airways hyperresponsiveness
does not develop
WT asthmatic mouse
PHIL mouseIm cured!
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Bronchial Hyperresponsiveness in Double/Triple
Transgenic mice
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Eosinophils Disease

• The seasons of the eosinophil
• Present concepts
• Anti-IL-5 treatment

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Mepolizumab study design
Stratification and 11 randomization Day 1
(baseline)
Mepolizumab 750 mg IV every 4 weeks until Week 32
Week 1 start flexible prednisone taper period,
based on blood eosinophil count and clinical
presentation
Washout of HES medications Prednisone
run-in/stabilization
Saline (placebo) IV every 4 weeks until Week 32
Screening/stabilization period of up to 6 weeks
36-week treatment period
Safety follow up (3 months after last dose)
Week 36
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Efficacy of Mepolizumab Rx
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Efficacy of Mepolizumab Rx
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Efficacy of Mepolizumab Rx
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Eosinophils Tissue Damage
This study shows that treatment with mepolizumab,
an agent designed to target eosinophils, results
in glucocorticoid sparing for patients negative
for FIP1L1PDGFRA who have the hypereosinophilic
syndrome.

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Eosinophils Disease

• The seasons of the eosinophil
• Present concepts
• Anti-IL-5 treatment

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Catapult-like release of mitochondrial DNA
byeosinophils contributes to antibacterial
defense

• LPS activates IL-5 stimulated eosinophils to
  release mitochondrial DNA (independent of cell
  death) in a catapult-like mannerin less than one
  second.
• Mitochondrial DNA granule proteins form
  extracellular structures able to bind and kill
  bacteria.
• After cecal ligation puncture, IL-5-tg mice
  show intestinal eosinophil infiltration
  extracellular DNA deposition in association with
  protection against microbial sepsis.
• These results suggest an eosinophil function that
  might be crucial for maintaining the intestinal
  barrier function after inflammation-associated
  epithelial cell damage, thus preventing the host
  from uncontrolled invasion of bacteria.

Shida Yousefi et al Nature Medicine, In press