Aspirin-triggered lipoxins override the apoptosisdelaying action of serum amyloid A in humanneutrophils: A novel mechanism...
Serum amyloid A• Marker of inflammation• Classical acute-phase protein• Serum concentration: <1 µg/mL to 1000 µg/mL• Progn...
Aims• whether SAA modulates constitutive neutrophil apoptosis• what signaling events are associated with this event• wheth...
SAA delays neutrophil apoptosisEl Kebir et al., J. Immunol. 179:616-622, 2007
SAA signals through ALXRSAA signals through ALXRSAAALXR** P<0.01n = 524 h cultureN-t-Boc-Phe-Leu-Phe-Leu-Phe (Boc2):antago...
Activation of Akt and ERKActivation of Akt and ERKAktERKPI-3kMEKSAAALXRSAA: 10 µg/ml
Blockade of Akt and ERK reversesBlockade of Akt and ERK reversesthe SAA actionsthe SAA actionsAktERKPI-3kMEKSAAALXRn = 5-7...
p pBADp pMcl-1BAD Mcl-1AktERKPI 3kMEKSAAALXPhosphorylation of BADChallenge: SAA, 10 µg/ml for 30 min
Aging?Mitochondrial Δψm ↓SAA prevents disruption ofSAA prevents disruption of Δψmn = 6* P<0.05** P<0.01
Mitochondrial Δψm ↓Cytochrome cAging?Cytochrome c releaseCytochrome c release***P<0.05P<0.01n = 6
Mitochondrial Δψm ↓Cytochrome cActivation ofcaspase-3Aging?SAA attenuates caspase-3 activationSAA attenuates caspase-3 act...
Mitochondrial Δψm ↓Cytochrome cActivation ofcaspase-3Aging?SAA attenuates caspase-3 activationSAA attenuates caspase-3 act...
Lipoxins do not affect neutrophil apoptosis020406080+Untreated 15-epi-LXA4 ATLa24 h culture%Viableorapoptoticcellsn = 5Joz...
15-epi-LXA4 reverses SAA suppression of apoptosisPretreatment with 15-epi-LXA4n = 5*P<0.05**P<0.01
15-epi-LXA4 inhibits SAA-induced signaling
Treatment with 15-epi-LXA4 at 60 min post-SAAn = 6
Treatment with 15-epi-LXA4 at 15 or 60 min post-SAA
SAAAnnexin-1LXA4ATLApoptosisALXR: A pleiotropic receptor
Conclusions• Our results provide evidence for a mechanism by which SAA maycontribute to inflammation by rescuing neutrophi...
Filep labLevente JózsefTarek KhreissDriss El KebirWanling PanJanos G. FilepFlow cytometry labSophie OuelletteChantal Baron...
ALXR: A pleiotropic receptorChiang et al, Pharmacol. Rev. 2006
SAA-induced phosphorylation of BAD throughactivation of Akt and ERK1/2
SAA signals through ERK1/2 and Aktn=5-7** P<0.01vs untreated††P<0.01vs. SAA24 h culture
SAA prevents disruption of ∆Ψmn=6* P<0.05** P<0.01
SAA inhibition of mitochondrial cytochrome c releaseand caspase-3 activation
SAA, caspase inhibition and neutrophil apoptosisn=5* P<0.05** P<0.0124 h culture
SAA-induced activation of Akt and ERK
Biosynthesis of lipoxins
Formyl-peptide receptors• FPR: high affinity receptor for fMLP• FPLR1/ALXR: low affinity receptor forfMLP plus many other ...
Survival signals for neutrophils
15-epi-LXA4 overcomes SAA suppression of apoptosisC SAA 15-epi-LXA4
Bioactive lipids, montreal  sept 2007
Bioactive lipids, montreal  sept 2007
Upcoming SlideShare
Loading in …5
×

Bioactive lipids, montreal sept 2007

219 views

Published on

Published in: Education, Health & Medicine
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
219
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
1
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • SAA is one of the classical acute phase proteins, and like C-reactive protein it is produced and secreted by the liver. serum concentration of SAA is below 1ug/ml in healthy subjects and could rise up to 1000ug/ml. SAA is used as prognostic factor in rheumatoid arthritis and in unstable angina. SAA was also detected at inflamed tissues. Surprisingly little is known of biological actions of SAA. There is evidence that SAA stimulates cytokines release from human neutrophils chemotaxis and promotes neutrophil adhesion to endothelial cells. Neutrophil activation is intimately linked to prolonged survival, a critical event in inflammation PMN have s short life span and die via apoptosis. However, pro-inflammatory mediators can rescue pmn from program cell death, for instance, RA and instable angina are associated with suppressed neutrophil apoptosis. Therefore we asked
  • An intriguing aspect of SAA biology is that its actions are mediated by a pleiotropic receptor, the lipoxin receptor. As I have shown SAA supresses the apoptotic machinery.Another ligand to the same receptor, annexin-1 was reported to accelerate neutrophil apoptosis, whereas the lipid mediators LXA4 and ATL by themselves had no effect on neutrophil fate. However, we have data indicating that they can override the antiapoptosis action of SAA and promotes resolution of inflammation. These findings add to the complexitiy of the biology of the LXAR, but also suggest a therapeutic potential for LXA4 and ATL when SAA formation is enhanced.
  • Bioactive lipids, montreal sept 2007

    1. 1. Aspirin-triggered lipoxins override the apoptosisdelaying action of serum amyloid A in humanneutrophils: A novel mechanism for resolution ofinflammationJános G. Filep,1Levente Jozsef,1Tarek Khreiss,1Wanling Pan,1Nicos A. Petasis,2Charles N. Serhan,3and Driss El Kebir11Research Center, Maisonneuve-Rosemont Hospital,University of Montreal, Montreal, QC, Canada H1T 2M42Department of Chemistry, University of Southern California, Los Angeles, CA 900893Center for Experimental Therapeutics and Reperfusion Injury,Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02155
    2. 2. Serum amyloid A• Marker of inflammation• Classical acute-phase protein• Serum concentration: <1 µg/mL to 1000 µg/mL• Prognostic factor in rheumatoid arthritis and unstable angina• Can be detected in inflamed tissues• Activates neutrophils• Undergo constitutive apoptosis• Can be rescued from cell death by pro-inflammatory mediators• Suppressed neutrophil apoptosis is a characteristic feature ofrheumatoid arthritis and unstable anginaNeutrophils
    3. 3. Aims• whether SAA modulates constitutive neutrophil apoptosis• what signaling events are associated with this event• whether such actions can be influenced by aspirin-triggered 15-epi-LXA4
    4. 4. SAA delays neutrophil apoptosisEl Kebir et al., J. Immunol. 179:616-622, 2007
    5. 5. SAA signals through ALXRSAA signals through ALXRSAAALXR** P<0.01n = 524 h cultureN-t-Boc-Phe-Leu-Phe-Leu-Phe (Boc2):antagonist of the fMLP receptor and ALXR
    6. 6. Activation of Akt and ERKActivation of Akt and ERKAktERKPI-3kMEKSAAALXRSAA: 10 µg/ml
    7. 7. Blockade of Akt and ERK reversesBlockade of Akt and ERK reversesthe SAA actionsthe SAA actionsAktERKPI-3kMEKSAAALXRn = 5-7** P<0.01 vs. untreated††P<0.01 vs. SAA24 h culture
    8. 8. p pBADp pMcl-1BAD Mcl-1AktERKPI 3kMEKSAAALXPhosphorylation of BADChallenge: SAA, 10 µg/ml for 30 min
    9. 9. Aging?Mitochondrial Δψm ↓SAA prevents disruption ofSAA prevents disruption of Δψmn = 6* P<0.05** P<0.01
    10. 10. Mitochondrial Δψm ↓Cytochrome cAging?Cytochrome c releaseCytochrome c release***P<0.05P<0.01n = 6
    11. 11. Mitochondrial Δψm ↓Cytochrome cActivation ofcaspase-3Aging?SAA attenuates caspase-3 activationSAA attenuates caspase-3 activationn = 5*P<0.05**P<0.01
    12. 12. Mitochondrial Δψm ↓Cytochrome cActivation ofcaspase-3Aging?SAA attenuates caspase-3 activationSAA attenuates caspase-3 activationn=5*P<0.05**P<0.01
    13. 13. Lipoxins do not affect neutrophil apoptosis020406080+Untreated 15-epi-LXA4 ATLa24 h culture%Viableorapoptoticcellsn = 5Jozsef et al., PNAS 99:13266, 2002Viable cellsAnnexin-V positive cells
    14. 14. 15-epi-LXA4 reverses SAA suppression of apoptosisPretreatment with 15-epi-LXA4n = 5*P<0.05**P<0.01
    15. 15. 15-epi-LXA4 inhibits SAA-induced signaling
    16. 16. Treatment with 15-epi-LXA4 at 60 min post-SAAn = 6
    17. 17. Treatment with 15-epi-LXA4 at 15 or 60 min post-SAA
    18. 18. SAAAnnexin-1LXA4ATLApoptosisALXR: A pleiotropic receptor
    19. 19. Conclusions• Our results provide evidence for a mechanism by which SAA maycontribute to inflammation by rescuing neutrophils from apoptosis.• SAA suppresses neutrophil apoptosis by preventing mitochondrialdysfunction and consequently inhibiting cytochrome c release andcaspase-3 activation.• 15-epi-LXA4 overrides the apoptosis delaying signals activated bySAA and thus redirecting neutrophils to apoptosis, consistent withfacilitation of the resolution of inflammation.
    20. 20. Filep labLevente JózsefTarek KhreissDriss El KebirWanling PanJanos G. FilepFlow cytometry labSophie OuelletteChantal BaronBlood donorsCollaboratorsLawrence A. Potempa (Immtech International)John S.D. Chan (CR-CHUM)Charles N. Serhan (Harvard University)Nicos A. Petasis (U. of Southern California)Acknowledgements
    21. 21. ALXR: A pleiotropic receptorChiang et al, Pharmacol. Rev. 2006
    22. 22. SAA-induced phosphorylation of BAD throughactivation of Akt and ERK1/2
    23. 23. SAA signals through ERK1/2 and Aktn=5-7** P<0.01vs untreated††P<0.01vs. SAA24 h culture
    24. 24. SAA prevents disruption of ∆Ψmn=6* P<0.05** P<0.01
    25. 25. SAA inhibition of mitochondrial cytochrome c releaseand caspase-3 activation
    26. 26. SAA, caspase inhibition and neutrophil apoptosisn=5* P<0.05** P<0.0124 h culture
    27. 27. SAA-induced activation of Akt and ERK
    28. 28. Biosynthesis of lipoxins
    29. 29. Formyl-peptide receptors• FPR: high affinity receptor for fMLP• FPLR1/ALXR: low affinity receptor forfMLP plus many other ligands• FPLR2: does not bind fMLP, ligands?
    30. 30. Survival signals for neutrophils
    31. 31. 15-epi-LXA4 overcomes SAA suppression of apoptosisC SAA 15-epi-LXA4

    ×