The Pioneer Transcription Factor Foxa2 Modulates T Helper Differentiation to Reduce Mouse Allergic Airway Disease

Foxa2, a member of the Forkhead box (Fox) family of transcription factors, plays an important role in the regulation of lung function and lung tissue homeostasis. FOXA2 expression is reduced in the lung and airways epithelium of asthmatic patients and in mice absence of Foxa2 from the lung epithelium contributes to airway inflammation and goblet cell hyperplasia. Here we demonstrate a novel role for Foxa2 in the regulation of T helper differentiation and investigate its impact on lung inflammation. Conditional deletion of Foxa2 from T-cells led to increased Th2 cytokine secretion and differentiation, but decreased Th1 differentiation and IFN-γ expression in vitro. Induction of mouse allergic airway inflammation resulted in more severe disease in the conditional Foxa2 knockout than in control mice, with increased cellular infiltration to the lung, characterized by the recruitment of eosinophils and basophils, increased mucus production and increased production of Th2 cytokines and serum IgE. Thus, these experiments suggest that Foxa2 expression in T-cells is required to protect against the Th2 inflammatory response in allergic airway inflammation and that Foxa2 is important in T-cells to maintain the balance of effector cell differentiation and function in the lung.

Modulating Th2 Cell Immunity for the Treatment of Asthma

It is estimated that more than 339 million people worldwide suffer from asthma. The leading cause of asthma development is the breakdown of immune tolerance to inhaled allergens, prompting the immune system's aberrant activation. During the early phase, also known as the sensitization phase, allergen-specific T cells are activated and become central players in orchestrating the subsequent development of allergic asthma following secondary exposure to the same allergens. It is well-established that allergen-specific T helper 2 (Th2) cells play central roles in developing allergic asthma. As such, 80% of children and 60% of adult asthma cases are linked to an unwarranted Th2 cell response against respiratory allergens. Thus, targeting essential components of Th2-type inflammation using neutralizing antibodies against key Th2 modulators has recently become an attractive option for asthmatic patients with moderate to severe symptoms. In addition to directly targeting Th2 mediators, allergen immunotherapy, also known as desensitization, is focused on redirecting the allergen-specific T cells response from a Th2-type profile to a tolerogenic one. This review highlights the current understanding of the heterogeneity of the Th2 cell compartment, their contribution to allergen-induced airway inflammation, and the therapies targeting the Th2 cell pathway in asthma. Further, we discuss available new leads for successful targeting pulmonary Th2 cell responses for future therapeutics.

Dupilumab for the treatment of asthma

INTRODUCTION

Dupilumab (REGN668/SAR231893), produced by a collaboration between Regeneron and Sanofi, is a monoclonal antibody currently in phase III for moderate-to-severe asthma. Dupilumab is directed against the α-subunit of the interleukin (IL)-4 receptor and blocks the IL-4 and IL-13 signal transduction. Areas covered: Pathophysiological role of IL-4 and IL-13 in asthma; mechanism of action of dupilumab; pharmacology of IL-4 receptor; phase I and phase II studies with dupilumab; regulatory affairs. Expert opinion: Patients with severe asthma who are not sufficiently controlled with standard-of-care represent the target asthma population for dupilumab. If confirmed, efficacy of dupilumab in both eosinophilic and non-eosinophilic severe asthma phenotype might represent an advantage over approved biologics for asthma, including omalizumab, mepolizumab, and reslizumab. Head-to-head studies to compare dupilumab versus other biologics with different mechanism of action are required. Pediatric studies with dupilumab are currently lacking and should be undertaken to assess efficacy and safety of this drug in children with severe asthma. The lack of preclinical data and published results of the completed four phase I studies precludes a complete assessment of the pharmacological profile of dupilumab. Dupilumab seems to be generally well tolerated, but large studies are required to establish its long-term safety and tolerability.