Hepatic Injury Secondary to Renal Ischemia-Reperfusion (I/R) Injury:
Senior Research Presentation - Use of CO to treat ischemia reperfusion injury
Transcript of Senior Research Presentation - Use of CO to treat ischemia reperfusion injury
Carbon Monoxide For Therapy?The Protective Characteristics of Carbon Monoxide Used to Treat Ischemia Reperfusion Injury
Joshua A. Mickle
Advisor:Prof. Jennifer Hancock
Tuesday, March 30th, 2010
BackgroundIschemia reperfusion injury (IRI)
◦Damage caused by the occlusion and subsequent return of blood supply to tissue
http://hyperbaricworx.com.au/images/How2.png
Why does reperfusion cause damage?
Combination of factors◦Local and systemic inflammatory
response Leukocyte activation Adherence to vessel walls Transmigration to interstitial space Increased edema, clotting, permeability
Collard & Gelman, 2001, 1134
Why does reperfusion cause damage?
Ischemic conditions - Anaerobic Metabolism
Oxidative enzymes produce Reactive Oxygen
Species (ROS)
ROS damage cell membranes - lipid
peroxidation
Cell Death
ReperfusionLarge influx of O2
What is Carbon Monoxide (CO)?Colorless, odorless, poisonous gas
◦CO greater affinity than O2 for Hemoglobin
◦Hb Unable to deliver O2
◦Disrupts cell respiration and triggers hypoxia
http://www.jems.com/Images/CO_Fig1_tcm16-186547.jpg
Why use CO for treatment?
CO produced naturally in bodyHeme Oxygenase-1 system (HO-
1)◦ HO-1 converts heme molecule into
CO, iron, and biliverdin
http://www.bioscience.org/2007/v12/af/2130/figures.htm
Why use CO for treatment?Oxidative stress shows increase
in HO-1◦Leads to increase in CO
concentration in blood◦Possibly a mechanism of protection
against reactive oxygen speciesAvailabilityRelatively well-understood
toxicologyLOW CONCENTRATIONS
Current Treatments for IRIIschemic preconditioningTherapeutic hypothermiaAnti-leukocyte therapyIntroducing radical scavengers
and antioxidantsTreatment of symptoms following
damage
HypothesisCO therapy is a viable option for
further investigation and eventual use on humans alongside or replacing the current treatment options for IRI.
CO Treatment Following StrokeStroke induced on rats
◦(Zeynalov E, Dore`, 2008)◦90 min. occlusion of Middle Cerebral
Artery
Moore & Dalley, 2006, 929
CO TreatmentDuring reperfusion
◦subjected to various concentrations of CO
◦exposed at 0, 1, or 3 hrs following reperfusion Air
At 0h125ppm
At 0h250ppm
At 0h
250ppmAt 1h
250ppmAt 3h
All for 18h of total exposure
Analysis of RecoveryNeurological Deficit Scores (NDS)
◦Conducted at: Onset of reperfusion 24hrs 48hrs
◦Scores range from 0 – 4Scor
eDescription
0 Normal motor function
1 Flexion of torso and contralateral forelimb when held by tail
2 Circling to the contralateral side, but normal posture at rest
3 Leaning to the contralateral side at rest
4 No spontaneous movement
Good
Bad
Results
Hours after Reperfusion
Neurological Deficit Score
0ppm CO
125ppm CO
250ppm CO
250ppm CO
0h 2 2 2 2
24h 2 1.5 2 1
48h 2 2 1 1
Also AnalyzedBrain tissue
◦Sliced into 2mm sections◦Stained to show metabolic activity
Posterior
Anterior
Brain Edema◦Ipsilateral and contralateral
hemispheres separated◦% Brain Water = [(Wet – Dry)/Wet] x
100
Also Analyzed
Not only in the BrainCO treatment in rat heart
transplant model◦Akamatsu et al., 2004
Comparison of CO therapy during reperfusion to:◦HO-1 activation◦Air inhalation
ProceduresHeart transplant
◦Success/failure – % survivalCO Exposure
◦Varying exposure to donor, graft, and/or recipient
◦400ppm
• Induces HO-1 expressionCobalt
protoporphyrin (CoPPIX)
• Reverses protective effect of HO-1
Zinc protoporphyrin
(ZnPPIX)
Reagents and Results
ResultsHighest survival rate
◦Donor and graft exposure◦Donor, graft, and recipient exposure
Interesting to note◦Donor and Recipient exposure only
Other studiesSimilar results in liver and lung
grafts◦Both in vivo and ex vivo◦(Amersi et al., 2002; Kohmoto et al.,
2006)Upregulation of HO-1 system
◦Increases CO endogenously◦(Amersi et al., 1999)
Current goal◦Investigate mechanisms behind
these results
Limitations to current studiesSmall sample sizesSmall animal models (rats and
mice)Performed only on healthy
specimensAlthough better, still low survival
rate◦Need to improve before human trials
Long term effectsDosage and duration of CO
treatment
Contradiction among studiesMechanisms of action
◦Anti-inflammatory◦Anti-apoptotic◦Other HO-1 byproducts
Conclusions & Implications
Compared to no IRI treatment:◦CO therapy shows significantly
improved tissue functioningPromising for future treatments
of IRIMust further understand
mechanism before clinical implementation
References Akamatsu Y, Haga M, Tyagi S, Yamashita K, Graca-Souza AV,
Ollinger R, Czismadia E, May GA, Ifedigbo E, Otterbein LE, Bach FH, Soares MP. 2004. Heme- oxygenase-1-derived carbon monoxide protects hearts from transplant-associated ischemia reperfusion injury. The FASEB Journal. 18: 771-782.
Amersi F, Shen X, Anselmo D, Melinek J, Iyer S, Southard D J, Katori M, Volk H, Busuttil R W, Buelow R, Kupiec-Weglinski J W. 2002. Ex-vivo exposure to carbon monoxide prevents hepatic ischemia/reperfusion injury through p38MAP Kinase pathway. Hepatology. 35(4): 815-823.
Amersi F, Buelow R, Kato H, Ke B, Coito AJ, Shen X, Zhao D, Zaky J, Melinek J, Lassman CR, Kolls JK, Alam J, Ritter T, Volk HD, Farmer DG, Ghobrial RM, Busuttil RW, Kupiec-Wegelski JW. 1999. Upregulation of heme oxygenase-1 protects genetically fat Zucker rat livers from ischemia/reperfusion injury.
The Journal of Clinical Investigation. 104(11): 1631-1639. Kohmoto J, Nakao A, Kaizu T, Tsung A, Ikeda A, Tomiyama K, Billiar
TR, Choi AMK, Murase N, McCurry KR. 2006. Low-dose carbon monoxide inhalation prevents ischemia/reperfusion injury of transplanted rat lung grafts. Surgery. 140(2): 179-185.
Zynalov E, Doré S. 2009. Low doses of carbon monoxide protect against experimental focal brain ischemia. Neurotoxicity Research. 15(2): 133-137.
AcknowledgementsProf. HancockDr. BrownCapstone ClassmatesTeammates
Questions?