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

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

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

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

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

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

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

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

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

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

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

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?

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