Transcript Slide 1

Part I: Fundamentals of Immunology
Part II: The Role of Genetics in
Immunosuppression
John Ryan, Ph.D.
Professor, VCU Department of
Biology
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My shameless recruiting plug…
• URMs represent 25% of the U.S. population
• The number of URMs receiving science and engineering PhDs increased 400%
from 1955-2006….
• But this is still less than 5% of the PhDs awarded
• VCU has a URM population of approximately 25% in Biology, Chemistry, and
related fields. We are committed to encouraging their participation in research.
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The Basic Immune Response
Tissue
Blood
APC
APC
Lymph Node
Th
Th
Th
Th
Th
Th
B
B
B
B
B
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Immunity: The Game
Antigen Table
Antigen Presenting cells
T cells
B cells
Lymph Node Table
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Fundamentals of Asthma Pathogenesis
John Ryan, Ph.D.
Professor, Biology Department
Virginia Commonwealth University
Asthma Pathophysiology
•Allergic asthma begins as an acute reaction, with mast cells driving bronchoconstriction,
coughing, tissue swelling, and clogging of the small lower respiratory tract airways with mucus.
•The result is air-trapping. White blood cells can be recruited.
•Chronic asthma is maintenance of this inflamed condition, where the infiltrating white blood
cells remain in the lung due to constant allergen exposure. While the response is similar to the
acute asthma, the severity grows. Airways can become totally occluded with mucus. Damage to
the epithelium leaves the bronchioles hyperresponsive, with bronchoconstriction following
many chemicals or irritants.
•Bacterial and viral infections can follow, and their eliciting a strong Th2 response worsens the
asthma. Rhinovirus in particular causes asthma exacerbations in children.
Ag
Th2
B
Mast Cell
Inflammatory mediators
causing cells to invade,
airways to be
hyperresponsive
Asthma Pathology
Recall that Fαr4
Tissue sections from pt who
died of allergic asthma. MP
represents mucus plug in
airway. Panel B shows
eosinophilic infiltration around
the lumen of the airway (L).
Global asthma rates
Nature, 2011
Oddities include Puerto Rico, with asthma rates of 30% among
children, 3X higher than other Hispanics, even when living in the
U.S. mainland. By comparison, Mexican Americans have very low
asthma rates.
Why is asthma so common?
The Hygiene Hypothesis
•Because the increase in asthma in particular is most overt in developed western nations, and fairly
uncommon in third world countries, one theory has received much support.
• Helper T cells (Th) organize the immune response. A specialized form of helper T cells, called Th2,
promote allergic disease. Th2 cells appear to develop in the absence of significant bacterial infection.
Since modern countries have protection from infection, this may be increasing the Th2 response in a
way that is pathological.
Th1
Protective
Parasitic infection
Th2
Kill intracellular pathogens
Kill extracellular pathogens
Th0
Pathological
Th2
Asthma
Th2
Asthma
Therapeutic Strategies for Treating Allergic Disease
•Avoidance of allergens.
•Allergen Immunotherapy. Accomplished by injecting Ag in hopes of including Th2 cell anergy
or Th1 responses to shift balance toward Th1/IgG production.
• Allergen Desensitization involves slowly injecting the patient with an increasing dose of the
antigen over a period of hours. This appears to “tolerize” the mast cells to the antigen. This is
mostly used to treat patients with drug to which they are reactive (e.g. oxaliplatin)
•Pharmacologic:
•Bronchodilator/Vasoconstrictors, like albuterol for asthma; epinephrine for systemic
anaphylaxis.
•Antihistamines (anti-H1) used to treat rhinitis, urticaria. (Claritin)
•Leukotriene inhibitors for asthma (Singulaire).
•Costicosteroids for asthma, rhinitis, eczema. (Nasonex)
•Cromolyn sodium for rhinitis and asthma.(Nasocrom)
• New therapy with an anti-IgE blocking antibody appears to block mast cell activation
(Xolair).
Effect of HMG-CoA reductase inhibitors (statins)
on mast cells: Genetic Background Matters
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Mevalonic Acid Pathway
Mevalonic Acid Pathway
Mevalonic Acid Pathway
Mevalonic Acid Pathway
Studying the effects of Fluvastatin on mast cells
from different genetic backgrounds
Bone marrow derived mast cells
C57BL/6
Th1-skewed immune response
129/Sv
Th2-skewed immune response
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Studying the effects of Fluvastatin on mast cell
function and survival
Bone marrow-derived mast cells
IgE+/- Fulvastatin 16hrs
Antigen
Supernatants collected after 16 hours
Measure cytokines by ELISA
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M
S
Fl O
u
Fl va 5
uv
a
Fl 1 0
uv
a
Fl 2 0
uv
a
4
D 0
M
S
Fl O
u
Fl va 5
uv
a
Fl 1 0
uv
a
Fl 2 0
uv
a
40
D
IL-13 pg/mL
M
2000
B.6
S
Fl O
u
Fl va 5
uv
a
F l 10
uv
a
F l 20
uv
a
4
D 0
M
S
Fl O
u
Fl va 5
uv
a
F l 10
uv
a
F l 20
uv
a
40
B.6
M
3000
MCP-1pg/mL
4000
D
S
Fl O
u
Fl v a 5
uv
a
F l 10
uv
a
F l 20
uv
a
4
D 0
M
S
Fl O
u
Fl v a 5
uv
a
F l 10
uv
a
F l 20
uv
a
40
D
TNF pg/mL
Th2 Genetic Background can Yield Resistance to Fluvastatin
20000
129
B.6
1000
5000
0
0
2500
2000
129
1500
1000
500
0
129
15000
10000
a+
M
A
10
A
00
10
a
XL
00
XL
1000
M
uv
a
XL
Fl
uv
SO
TNF pg/mL
N.S
Fl
uv
uv
a+
Fl
M
on
t
0
D
XL
****
C
00
00
4000
SO
10
10
6000
M
A
A
XL
8000
D
M
M
a
IL-6 pg/ml
10000
Fl
a+
uv
a+
a
XL
on
t
Fl
uv
SO
C
Fl
uv
M
SO
D
M
2000
Fl
uv
Fl
D
Mevalonic Acid Reverses the effects of
Fluvastatin
4000
NS
3000
2000
**
0
Fluvastatin Induces Mast Cell Death
100
Cells
Dead
%%
apoptosis
80
60
B6
40
129
20
0
0
10
20
30
mM of Fluvastatin
Fluvastatin (mM)
40
50
Fluvastatin Suppresses Mast Cell Migration
Fold Migration
50
40
30
20
10
0
Control SCF
DMSO
Control
SCF Control
Fluvastatin
C57BL/6
SCF
Control
DMSO
129/Sv
SCF
Fluvastatin
Conclusions
Fluvastatin treatment
in C57BL/6 strain Ag
FcЄRI
SCF
LAT1
C-KIT
Lyn
Grb2
SOS
Syk
Ras
Ras
SOS
Vav1
GTP
GTP
MAPK (ERK1/2/JNK/p38)
MAPK (ERK1/2/JNK/p38)
Cell survival
Migration/adhesion
Production of
inflammatory factors
The Ryan Lab, 2013
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The effect of Fluvastatin on IgE receptor signaling
C57BL/6 Cells
Asthma
(from ALA Report, 2012)
• A chronic inflammatory condition of the lungs that causes difficulty breathing.
• Not a form of COPD, since it is reversible.
• Epidemiology data of interest:
• Nearly 26 million Americans have asthma, of which 7 million are children.
Asthma rates nationally rose 59% from 1982-1996. Total direct health care
costs are approximately $16B annually.
• Highest rate is among 5-17 year-olds. Most common chronic illness of kids.
•Among children, asthma is slightly more common in boys – but among adults,
asthma is about 50% more common in women
• Issues that exacerbate asthma include 2nd hand smoke and obesity, either of
which increases asthma incidence 2-fold.
• 3388 people died from asthma in 2009, but the death rate has been declining steadily for
10 years. Major negative predictors for asthma death include: older, female, africanamerican or Puerto Rican. Death rate for Americans >65yo is about 5X higher than for
teenagers.
• A number of genetic polymorphisms predispose to asthma severity or
incidence. These include immune response genes that predispose to allergy
and other issues like beta-adrenergic receptor polymorphisms that decrease
drug responsiveness.
Allergic vs Non-Allergic Asthma
• It is important to note that a significant proportion of asthma patients, perhaps almost
half, present with a non-allergic form of the disease. This is also referred to as “intrinsic”
asthma.
• These patients differ from allergic asthmatics in a few interesting and important ways:
Allergic
Non-Allergic
Childhood onset
Adult onset
Family history
No family history
Symptoms induced by allergens
Elevated IgE
Significant Lung remodeling
Symptoms induced by stress, cold, exercise
Normal or reduced IgE
Little remodeling
Eosinophil influx
Neutrophil influx
Steroid responsive
Less steroid responsive
Mast cell
 Resident cell in many tissues
Best known for the causative agent
in allergic disease
 Inflammatory mediators released –
1. Granule-associated mediators – Histamine, Serotonin, proteases
2. Eicosanoids - Prostaglandin D2, Leukotriene C4
3. Cytokines and chemokines– IL-2, IL-13, IL-6, MCP-1, TNF α, CXCL-8
Mast Cell Activation
Mast Cell Activation
Mast Cell Activation
Mast Cell Activation
Mast Cell Activation
Mast Cell Activation
Mast Cell Activation
Mast Cell Activation
Mast Cell Activation