1. Respiratory Infection of Apo E
KO Mice Causes Excessive
Plaque Inflammation
Implication for triggering effect of flu in human
heart attack
Adeeba Akhtar MD, Silvio Litovsky, MD, Philip Wyde PhD,
Mohammad Madjid MD, Ward Casscells MD, James
Willerson MD, Morteza Naghavi MD.
2. Background
• The role of infection in atherosclerosis has been
known for years.
• A number of pathogens such as C. pneumonia,
HSV, CMV have been reported to be present in
the plaque and moreover related to CHD
• Other chronic infections such as H. pylori, and
dental infection were also found to increase
likelihood of chronic coronary heart disease.
3. Background
• However, acute effect of infection in
triggering coronary events has not received
as much attention.
• A number of retrospective epidemiological
studies have shown the relationship
between acute upper respiratory infection
and myocardial infarction.
4. Background
• The role of inflammation and inflammatory
cytokines in the development of vulnerable
plaque and plaque rupture is now well established.
• Increased circulating cytokines was shown to
accelerate plaque formation in Apo E mice.
• Influenza infection can increase thrombogenecity
of blood by increasing platelet aggregation.
• We have previously shown in a case-control study
that flu vaccination is associated with reduced
recurrence of MI.
5. Background
Therefore we have hypothesized :
• 1) Acute influenza infection of old Apo E
deficient mice may cause acute coronary
event and heart attack.
• 2) Acute influenza infection can increase
plaque inflammation and macrophage
infiltration, with or without rupture/erosion.
6. Study Design
42 ApoE Mice
Controls infected with Influenza virus
Hong Kong P9 LD50
9 Direct infection
24 Intranasal inoculation
9
33
6 sacrificed 3died
11sacrificed 13died
7. Procedure:
• We measured the baseline weight , heart rate,
pulse oximetry of all the infected mice and
measured these parameters again before
sacrificing.
• This was a short term (15 days) study and the mice
were sacrificed at 3, 5, 10, 15 days.
• After sacrifice we took the heart and aorta in
formalin and cut 5 sections for each aorta and one
mid-transverse ventricular section of the heart.
8. Examinations
• Weight (substitute for Temp)
• Oxygen sat.
• Pulse
• Lung virus titration.
• rtPCR for influenza virus.
• CBC and Hb.
• Blood smear.
• Multiple aorta and heart specimens for pathology
examinations, H&E, Movat, CD68, TUNEL, actin,
CD3 staining.
9. General Findings
• - As expected based on LD 50%, old mice
were prompted to die mainly due to
overwhelming lung infection . But we
sacrificed most of them at their maximum
load of infection.
• Significant weight loss occurred in all
infected mice but not in control mice.
55. Conclusion:
• One third of the infected mice developed this
inflammatory infiltrate associated with clusters of
platelets and occasionally fibrin overlying the
infiltrate.
• The infiltrate is polymorphic (macrophages,
smooth muscle cells, T-lymphocytes). Next set of
stainings will be done on frozen tissue to improve
antigenicity.
• Upregulation of inflammatory and procoagulant
cytokines and receptors will be investigated.
• Longer-term studies will investigate the possible
