Hedgehog signalling in gut inflammation and allergy

Background:
The project will impact on our understanding of food allergies, gut inflammation and gut homeostasis. An understanding of the molecular mechanisms that influence immune regulation in the gut is essential for the development of new strategies to treat childhood diseases of the gastro intestinal tract, such as inflammatory bowel disease (IBD). We have previously shown that Hedgehog signalling regulates peripheral T-cell responses and T helper differentiation and that the pathway is involved in other allergic diseases (asthma and atopic dermatitis), and the Hedgehog signalling pathway regulates gut development and homeostasis1-5. Here, we will investigate the impact of genetic manipulation of components of the Hedgehog signalling pathway on lymphocytes and leucocytes in the gut, in order to understand the influence of this pathway on gut allergy and inflammation.

Aims/Objectives:
The purpose of this project is to test the hypothesis that Hedgehog signalling influences lymphocyte and leucocyte populations in the gut, and thereby impacts on induction of gut inflammation, food allergy and inflammatory bowel disease. We will complete the following objectives:
1. We will test if T-cell and leucocyte populations isolated from the gut are influenced by mutation of Hedgehog pathway components.
2. We will test impact of mutation of components of the Hedgehog pathway (Gli3, Gli2, Shh, Ihh) or Hh-target genes on gut microbiota.
3. We will compare induction and severity of disease between Wildtype (WT) and Hedgehog pathway mutants in a mouse model of milk allergy.
4. We will compare induction and severity of disease between WT and Hedgehog pathway mutants in a mouse model of inflammatory bowel disease.

Methods:
This project will use constitutive and conditional mutant mouse models, in combination with in vitro functional assays and immunisations to investigate hedgehog signalling in gut inflammation an allergy. The project will involve flow cytometry, microscopy, molecular biology, RNA-sequencing and bioinformatics, analysis of microbiome, computational analyses, using methods described in 1-4.

Timeline:
Year one: Objective 1 and Objective 2;
Year two: Objective 3;
Year three: Objective 4.

References:
1. Furmanski AL, Barbarulo A, Solanki A, Lau CI, Sahni H, Saldana JI, D'Acquisto F, Crompton T. (2015) The transcriptional activator Gli2 modulates T-cell receptor signalling through attenuation of AP-1 and NFκB activity. J Cell Sci. 128, 2085.
2. Furmanski AL, Saldana JI, Ono M, Sahni H, Paschalidis N, D'Acquisto F, Crompton T. (2013) Tissue- derived hedgehog proteins modulate th differentiation and disease. J Immunol. 190, 2641.
3. Standing AS, Yánez DC, Ross R, Crompton T, Furmanski AL. (2017) Shh production and Gli signaling is activated in vivo in lung, enhancing the Th2 response during a murine model of allergic asthma. J Leukoc Biol. Feb 24. doi: 10.1189/jlb.3HI1016-438RR.
4. Papaioannou E, Yánez DC, Ross S, Lau CI, Solanki A, Chawda MM, Virasami A, Ranz I, Ono M, O’Shaughnessy RFL and Crompton T (2019). Sonic Hedgehog signalling limits atopic dermatitis via Gli2-driven immune regulation. Journal of Clinical Investigation (in press).
5. van den Brink, G.R., Hedgehog signaling in development and homeostasis of the gastrointestinal tract. Physiol Rev, 2007. 87(4): p. 1343-75.