Paper 3: Lyn activity, DSS colitis, IL-22 Flashcards
IL-22 (2)
- targets cells in barrier organs, such as intestinal epithelium, where it induces host defence, pro-survival, and proliferation factors
- in colitis injury models, IL-22 antagonizes inflammation and promotes wound healing
which cells create IL-22 (3)
- T cell subsets
- multiple subsets of ILCs
- production of IL-22 largely influenced by innate immune cells responses to TLR signals
Lyn (3)
- protein type
- expression in cells
- activation
- Src-family tyrosine kinase (SFK)
- expressed in all leukocytes except T cells
- activated by ligand binding to adhesion molecules, cytokine receptors, immunoreceptors, and TLRs
does Lyn amplify or restrict signal transduction
- depending on cell microenvironment, developmental stage, and type of stimulus, Lyn can either restrict or amplify signal transduction
Lyn^up mice (2)
- contain mutation in endogenous Lyn gene at C-terminal negative-regulatory tyrosine phosphorylation site
- leads to increased Lyn activity as inhibition mechanism is altered
what was the purpose of figure 1A - 1D
- investigate how changes in Lyn activity and associated changes in responses to PAMPs might alter intestinal homeostasis and susceptibility to inflammation
what was observed in figure 1A, 1B, 1C
- Lyn^up mice were protected from DSS compared with wt (less weight loss, longer colon length, less rectal bleeding)
what was observed in figure 1D
- Lyn^up mice had fewer crypt loss and less epithelial sloughing and ulceration compared to WT mice
what were the findings of figure 1A - 1D
- Lyn plays a protective role in DSS-induced colitis
what was the purpose of figure 1E - 1I
- given Lyn’s protective role in acute colitis, to investigate outcome of chronic inflammation in Lyn^up mice
what was observed in figure 1E - 1I
- Lyn^up could gain weight in recovery better than wt mice
- Lyn^up mice had reduced morbidity than wt
- Lyn^up mice had significantly longer colons compared to wt, indicated reduced chronic inflammation
- Lyn^up mice had reduced tumour number and load compared to controls
what are the findings from figure 1E - 1I
- Lyn activity protects mice from acute and chronic DSS-induced intestinal inflammation and reduced incidence of colitis-associated cancer
what is the purpose of figure 2
- investigate contribution of cytokine responses in Lyn-mediated protection from DSS-colitis
how are IL-22 and IL-23 connected
- IL-23 drives production of IL-22
what was observed in figure 2A, 2B, 2C (2)
- Lyn^up colons had significantly more IL-22 and IL-23 protein and mRNA production than wt
- increase seen as early as 2 days post-treatment, with significant increase in colon and detectable increase in serum
what was observed in figure 2D
- colonic epithelial cells isolated from Lyn^up mice showed consistent increase in STAT3 activation (indicated by phosphorylation of tyrosines), which is done by IL-22
what was observed in figure 2E
- elevated expression of antimicrobial lectins RegIIIg and RegIIIb and mucus protein Muc1 mRNAs, genes responses to STAT 3 which is induced by IL-22
what was observed in figure 2f
- no differences in weight change during acute phase of DSS treatment
- IL-22 neutralization resulted in significant delay in recovery of Lyn^up mice
what were the findings from figure 2
- increased production of IL-22 in Lyn^up mice acts tp enhance intestinal repair and may contribute to protection from DSS colitis
what is the purpose of figure 3
- to access the relative contributions of adaptive vs innate immune cells in limiting colitis in Lyn^up mice
what was observed in figure 3 (3)
- protection from DSS in Lyn^up mice was exaggerated in absence of adaptive immune system (Rag-/-)
- Rag-/-Lyn^up mice showed less weight loss and rectal bleeding and had longer and less inflamed colons than Rag-/- mice
- ceca of Rag-/- mice showed many more signs of inflammation and damage than Rag-/-Lyn^up mice
what were the findings of figure 3
- enhanced Lyn activity in innate immune cells is sufficient to protect mice from DSS-induced intestinal inflammation
what was the purpose of figure 4
- determine cell types responsible for increased IL-22 production of Lyn^up mice
what was observed in figure 4A (3)
- Lyn^up splenocytes produced more IL-22 than wt in response to IL-23 with or without LPS
- adaptive immune cells were not required for enhanced IL-22 production
- Lyn^up splenocytes IL-22 production was dependent on presence of CD90+ cells