The RESPImmun Faculty

	Eva BÖHM, PhD The role of JAK / STAT signaling in allergic asthma
Otto Loewi Research Centre, Division of Pharmacology, Medical University of Graz, Neue Stiftingtalstraße 6, A-8010 Graz; phone: +43-316-385 74103, fax: +43-316-385 79613, ✉ e-mail
websites: [RESPImmun]
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Eva Böhm is a pharmacologist with a major interest in allergy and asthma. She paved the way for the basophil activation test for Hymenoptera venom allergy into clinical routine diagnostics and made important contributions to the opposing roles of PGD₂ and PGE₂ and their receptors, DP₂ and EP₄, in eosinophil function and asthma models. With the help of Horst Olschewski and Peter Valentin Tomazic she intends to elucidate the alterations of the JAK / STAT signaling cascade as a predictive marker and therapeutic target in asthma and CRS. In vivo relevance will be shown with acute animal models (Leigh Marsh).

Project

Project 5: The role of JAK / STAT signaling in allergic asthma
Co-PI: Philipp Douschan

Background

Most proinflammatory cytokines and growth factors utilize the Janus kinases (JAK) signal transduction and activator of transcription (STAT) pathway, which has been linked to various inflammatory and autoimmune diseases. In mammals, there are four members of the JAK family and seven STATs. JAK1 and JAK3 play critical roles in the initiation of inflammation and have been investigated as potent therapeutic targets in a variety of inflammatory diseases. Ruxolitinib, a selective JAK1/2 inhibitor, has been used in the treatment of myelofibrosis and shown to impair dendritic cell functions. Tofacitinib, which mainly targets JAK1/3, has been effective in rheumatoid arthritis, inflammatory bowel disease, psoriasis, transplant rejection, or hematopoietic disorders such as myelofibrosis. Baricitinib, a selective JAK1/2 inhibitor has been developed for the treatment of rheumatoid arthritis, atopic dermatitis and systemic lupus erythematosus. Indeed, current literature indicates that JAK / STAT inhibitors promote regulatory effects on inflammatory cells in vivo and in vitro; however, the exact mechanisms are fully unclear. Moreover, so far neither in vitro nor in vivo studies have specifically investigated the role of JAK / STAT signaling in eosinophil function and allergic asthma.

Hypothesis and objectives

Our recent data provide evidence that JAK / STAT signaling plays a crucial role in the pathophysiology of allergic disorders by regulating eosinophil function. In this project we will investigate the activation pattern of the JAK / STAT pathway in peripheral blood leukocytes from allergic and non-allergic asthmatic patients as compared to healthy controls. As JAK / STAT signaling can change upon cell activation, we will define the JAK / STAT activation status of infiltrated leukocytes in nasal mucus from patients. To prove the in vivo relevance of these approaches an acute model of house dust mite-induced asthma will be used.

Methodology

Year 1: The PhD student will learn how to isolate leukocytes, especially eosinophils, from peripheral blood. JAK / STAT expression will be quantified by real-time PCR, western blot, fluorescence microscopy and flow cytometry. Year 2: The student will investigate the biological relevance of JAK1/2 inhibition on human eosinophils by shape change, integrin up-regulation and chemotaxis using flow cytometry. In vivo relevance will be demonstrated by investigation of chemotaxis of ex-vivo cultured bone-marrow eosinophils installed into eosinophil-deficient ΔdblGATA recipient mice. Year 3 – 4: In a translational aspect, the student will use well established experimental mouse models for allergic asthma to investigate the therapeutic effect of JAK1/2 inhibition on lung function (using Flexivent measurements) and leukocyte recruitment (multicolor flow cytometry). Cytokine profiles will be determined by multiplex ELISA. Lung tissue will be stained by immunohistochemistry. Lipid mediators will be determined by LC-MS.

Input from collaborations within the RESPImmun programme

Horst Olschewski will recruit asthmatic patients and collect blood and plasma samples,
Julia Kargl will train the student in isolation techniques for inflammatory cells from lung tissue,
Leigh Marsh will train the student in experimental mouse models of allergy and asthma,
Peter Valentin Tomasic will collect nasal mucus samples from allergic patients,
Gerald Höfler will support the student with his expertise on lung pathology,
Andrea Olschewski will support with in vivo cell calcium imaging.