1. Modulation of Gene Expression via Disruption Of NF-kB Signaling by a
Bacterial Small Molecule
Kravchenko et al. Science 2008
Paulina Blazejewska

2. Innate Immunity & Pathogen
Two phases of the innate response
Recognition:
nonspecific &
specific effectors
Innate Immunity
0-4 hours
Infection
Removal
Early induced
Innate response
4-96 hours
Recognition:
microbial-associated
molecular patterns
Recognition:
microbial-associated
molecular patterns
Infection
Inflammation/
effector cells
Removal

3. Conserved receptor e.g. TLR4 TLR4-independent mechanism
LPS
C12 ?
Conserved receptor e.g. TLR4
TLR4-independent
mechanism
NFκB
IkB
IkB kinase (IKK) activity
IκBα & RelA P
proinflammatory cytokines e.g. TNFα
p38 protein kinase pathway
Pathogen elimination
Bacteremia & persistant infection

4. Objectives
What is the strategy used by pathogens to attenuate the innate immune system ?
How to maintain local persistent infection ?

5. Experimental approach
Comparison the macrophages response and the phosphorylation of p38 after infection with Salmonella typhimurium , Staphylococcus aureus or Pseudomonas aeruginosa
Biochemical effect of LPS and C12 and their combination
C12 in the late stage of LPS stimulation
Role of C12 in mice

6. Comparison the macrophages response and the phosphorylation of p38 after infection with S. typhimurium , S. aureus or P. aeruginosa
similar amount of p-p38
upon activation with S. typhimurium and S. aureus the patterns of IκBα degradation and resynthesis were comparable
substantial delay in IκBα resynthesis after infection with
P. aeruginosa
- P. aeruginosa deficient in lasL (C12 synthesis) showed the normal profile in IκBα
C12 affects the NFκB pathway in macrophages

7. Experimental approach
Comparison the macrophages response and the phosphorylation of p38 after infection with Salmonella typhimurium , Staphylococcus aureus or Pseudomonas aeruginosa
Biochemical effect of LPS and C12 and their combination
C12 in the late stage of LPS stimulation
Role of C12 in mice

8. Biochemical effect of LPS and C12 and their combination
C12 impairs the expression and phosphorylation of IκBα
C12 modulates the phosphorylation of RelA but not expression
- IκBβ degradation was disrupted in the presence of C12
p-IκBβ remains bound to RelA in the absence of IκBα
C12 reduces the early phase of IKK activation by LPS

9. Experimental approach
Comparison the macrophages response and the phosphorylation of p38 after infection with Salmonella typhimurium , Staphylococcus aureus or Pseudomonas aeruginosa
Biochemical effect of LPS and C12 and their combination
C12 in the late stage of LPS stimulation
Role of C12 in mice

10. C12 in the late stage of LPS stimulation
the addition of C12 to the macrophages (pretreated with LPS) resulted in rapid reduction of p-IκBα and p-RelA
C12 also impairs other NFkB-regulated genes
- C12 acts as a general modulator of the NFkB pathway

11. Experimental approach
Comparison the macrophages response and the phosphorylation of p38 after infection with Salmonella typhimurium , Staphylococcus aureus or Pseudomonas aeruginosa
Biochemical effect of LPS and C12 and their combination
C12 in the late stage of LPS stimulation
Role of C12 in mice

12. Role of C12 in mice
LPS-induced responses were suppressed by C12
inhibition of TNF by C12 in LPS-stimulated leukocytes may be beneficial for the survival of both pathogen and host
C12 mediated disruption of NFkB attenuates TLR-4-dependent innate responses – promoting persistent infection with P. aeruginosa
What is a mammalian C12 receptor?

13. Thank you
for your attention
&
Merry Christmas
and a Happy New Year !