The long-term goal of this project is to understand how the dysregulation of certain keratinocyte functions, by altering the cells' interactions with te skin microbiome, can impair epidermal barrier function, leading to features resembling those of atopic dermatitis (AD) and the development of high serum levels of IgE. Mouse RabGEF1 was discovered as a negative regulator of mast cell activation, and mice globally deficient in RabGEF1 rapidly develop AD-like skin [pathology]. However, conditional deletion of Rabgef1 specifically in mouse keratinocytes is sufficient to drive AD-like skin [pathology] and the development of high levels of serum IgE (as is also seen in AD patients). Moreover, the severe skin disease observed in RabGEF1- deficient mice critically depends on keratinocyte-intrinsic expression of MyD88, an adaptor molecule that mediates signaling by several Toll-like receptors (TLRs). [Expression of RabGEF1 protein] is markedly decreased in lesional skin from patients with AD as compared to healthy skin, whereas MYD88 mRNA expression is significantly increased in lesional skin specimens from AD patients. Since skin is continuously exposed to microorganisms that are a rich source of TLR ligands, we will evaluate to what extent the skin microbiome and keratinocyte TLRs can contribute to the MyD88-dependent AD-like skin [pathology] observed when keratinocytes lack RabGEF1. We will use RabGEF1-deficient mouse and human keratinocytes to analyze in vitro the molecular mechanisms by which RabGEF1 regulates MyD88-dependent signaling pathways. Finally, we will assess how keratinocyte-restricted [complete or partial] reductions in RabGEF1 expression can influence systemic sensitization to allergens via the skin, with the later development of allergic inflammation in distant organs such as the lung. We propose three specific aims to test the General Hypothesis: The development of skin pathology with features of atopic dermatitis, and elevated serum IgE, in RabGEF1-deficient mice reflects the ability of RabGEF1 to maintain skin [barrier and immune] functions by down-regulating pathways initiated by MyD88-dependent signaling in keratinocytes.
Aim 1 : Define the contributions of MyD88, Toll-like receptors (TLRs), and the skin microflora in the AD-like skin [pathology] induced by keratinocyte-specific Rabgef1 deletion in vivo.
Aim 2 : Determine the mechanisms by which RabGEF1 negatively regulates MyD88-dependent functional responses and signaling in keratinocytes.
Aim 3 : Determine the mechanisms by which RabGEF1 deficiency in keratinocytes influences skin sensitization to allergens and the development of the atopic march. This project will clarify how an intrinsic impairment in keratinocyte function due to diminished RabGEF1 can contribute to AD-like skin [pathology]. Ultimately, pursuing such work may enable the discovery of novel therapeutic targets for the prevention or treatment of AD and perhaps other atopic or inflammatory disorders.
Atopic dermatitis ('eczema') affects up to 15-25% of children and 3% of adults in the US. It is the most common inflammatory skin disease with substantial medical and socio-economic impact on the affected families and high costs to the health care system. By defining how RabGEF1, a natural protein of the skin, can maintain skin barrier function and suppress skin inflammation, this project may lead to the discovery of new approaches to reduce the burden of this clinically and economically important disorder.
|Klein, Ofir; Roded, Amit; Hirschberg, Koret et al. (2018) Imaging FITC-dextran as a Reporter for Regulated Exocytosis. J Vis Exp :|
|Mukai, Kaori; Tsai, Mindy; Saito, Hirohisa et al. (2018) Mast cells as sources of cytokines, chemokines, and growth factors. Immunol Rev 282:121-150|
|Tsai, Cheng-Ting; Mukai, Kaori; Robinson, Peter V et al. (2018) Isotype-specific agglutination-PCR (ISAP): A sensitive and multiplex method for measuring allergen-specific IgE. J Allergy Clin Immunol 141:1901-1904.e15|
|Gaudenzio, Nicolas; Marichal, Thomas; Galli, Stephen J et al. (2018) Genetic and Imaging Approaches Reveal Pro-Inflammatory and Immunoregulatory Roles of Mast Cells in Contact Hypersensitivity. Front Immunol 9:1275|
|Yu, Mang; Mukai, Kaori; Tsai, Mindy et al. (2018) Thirdhand smoke component can exacerbate a mouse asthma model through mast cells. J Allergy Clin Immunol 142:1618-1627.e9|
|Reber, Laurent L; Hernandez, Joseph D; Galli, Stephen J (2017) The pathophysiology of anaphylaxis. J Allergy Clin Immunol 140:335-348|
|Klein, Ofir; Roded, Amit; Zur, Neta et al. (2017) Rab5 is critical for SNAP23 regulated granule-granule fusion during compound exocytosis. Sci Rep 7:15315|
|Galli, Stephen J; Starkl, Philipp; Marichal, Thomas et al. (2017) Mast Cells and IgE can Enhance Survival During Innate and Acquired Host Responses to Venoms. Trans Am Clin Climatol Assoc 128:193-221|
|Boyd, Scott Dexter; Hoh, Ramona Amy; Nadeau, Kari Christine et al. (2017) Immune monitoring for precision medicine in allergy and asthma. Curr Opin Immunol 48:82-91|
|Laiño, Jonathan; Wangorsch, Andrea; Blanco, Frank et al. (2017) Targeting of Immune Cells by Dual TLR2/7 Ligands Suppresses Features of Allergic Th2 Immune Responses in Mice. J Immunol Res 2017:7983217|
Showing the most recent 10 out of 24 publications