|M.Sc Student||Koren Carmi Ifat|
|Subject||FSL-1 Induced Inflammatory Factors Involved in Atopic|
Dermatitis Like Model in Keratinocytes - The
Involvment of p38 MAPK and NF-kB
|Department||Department of Medicine||Supervisors||Professor Abraham Reznick|
|Professor Snait Tamir|
|Full Thesis text|
Background: Atopic diseases such as asthma and atopic dermatitis are characterized by epithelial secretion of thymic stromal lymphopoietin (TSLP), interleukin 33 (IL33) and interleukin 25 (IL25), which have been shown to drive TH2 immune reaction. Nuclear factor κB (NFκB) is a master regulator of inflammation known to be involved in the production of numerous inflammatory agents and reactive oxygen species (ROS), which are known to mediate the inflammatory response and to cause tissue damage.
Understanding signal transduction pathways and factors involved in producing atopic response is crucial to the achievement of new and effective therapy and relief to patients.
Aim & Methods: This research aimed to reveal factors involved in signaling pathways in an atopic dermatitis-like model based on FSL-1 (diacylated lipoprotein)-stimulated in HaCat keratinocytes. Cytokine expression of cells treated with the stimulator FSL-1 and inhibitors to: TLR2/6 (human monoclonal anti TLR6 antibody), oxidative stress (N-actylcysteine), p38 MAPK (mitogen activated protein kinase) (SB202190, SB203580) and IKK (IMD0354) was measured by real time PCR. NF-kB and p38 MAPK activation of these cells was studied by western blot. Intracellular oxidative level was monitored by dichlorofluorescein (DCF) assay.
Results: HaCat keratinocytes, stimulated with 1μg/ml FSL-1 expressed higher levels of IL33 mRNA (dependent on NF-κB activation) and higher levels of TNFα mRNA (dependent on p38 activation) than non-stimulated cells. ROS were produced via binding of FSL-1 to TLR2/6. TSLP and IL25 mRNA expression was found to be dependent on TLR2/6 binding by FSL-1 and p38 MAPK activation. Endogenously-produced oxidative stress was revealed to take part in the activation of NF-κB and expression of TNFα, IL33 and TSLP, according to the decrease in their expression when cells were exposed to NAC.
Conclusions: The mechanisms by which FSL-1 activates mRNA expression of AD-related cytokines involve multifaceted signal transduction pathways, including those of p38 MAPK and NF-kB. Oxidative stress has a secondary role in these pathways.
Although this research revealed substantial components of the signal transduction pathways induced by FSL-1, more studies are required to elucidate the interaction between these pathways and to produce an in vitro model for atopic dermatitis.