Staff Profile

Research Statement
Dendritic cells (DCs) are professional antigen presenting cells capable of generating strong T cell dependent primary immune responses.  Langerhans cells (LCs) constitute a specialized subset of DCs that reside in their immature state in the epidermis of the skin and pluri-stratified mucosal epithelia, which migrate toward cutaneous-draining lymph nodes (CLNs) upon antigen capture and maturation.  The current ‘LC paradigm' suggests that LCs act as sentinels in the skin by detecting incoming skin pathogens, integrating the information on both the foreign threat and state of inflammation of the tissue where they originated, and conveying all of this information to T cells in CLNs, which subsequently determines both the magnitude and the functional polarization of adaptive immune response to skin antigens.  In addition, under "steady-state" non-inflammatory conditions it is thought that LCs play an important role in tolerance. 

My previous research was to establish the exact role of LCs and dermal-derived DCs using genetically engineered mouse models. We recently engineered knock-in mice that express an enhanced green fluorescent protein (EGFP) under the control of the langerin (CD207) gene, a C-Type lectin expressed by LCs which enabled us to further characterize LCs, and directly study the dynamics of LCs both in vivo and ex vivo.  A second knock-in was developed to specifically eliminate LCs in vivo by placing the human diphtheria toxin receptor under the control of the langerin gene.  These transgenic lines will enable us to study the development and function of LCs during both steady-state conditions (tolerance) and in inflammatory contexts.

My research currently focuses on the role of pulmonary DC subsets in different models of lung inflammation.  Recently a major DC population defined to be integrin aE-b7+CD207+CD11b- was found to be specifically localised at the basal lamina of the bronchial epithelia and arterioles of the lung, suggesting that they may be specifically involved in antigen capture and transport to mediastinal lymph nodes of the lung.  Integrin aE-b7+ mediates adhesion of intraepithelial lymphocytes and DCs to E-cadherin, an epithelial specific cadherin involved in cell to cell adhesion.   It is becoming increasingly clear that different DC subsets are involved in specialized roles and effector function. Together these observations suggest that pulmonary CD207+CD11b- DCs are key antigen-presenting cells of the lung capable of migrating across the airway epithelia for antigen sampling, transport and presentation to memory and/or effector cells in regional MLNs. Therefore, the LangEGFP and LangDTR models offer the unique possibility of addressing the role of CD207+ pulmonary DCs both during steady-state and inflammatory conditions, such as viral infection and experimentally induced asthma.  The ability to track and specifically ablate these cells both in vivo and ex vivo may identify these lung DCs as the key proinflammatory cells necessary for Th1 and/or Th2 cell stimulation during airway inflammation.

Furthermore, to align myself with the immunology group within the CII, we are currently investigating the involvement of SOCS proteins in DC cytokine signalling and determining the impact of SOCS protein ablation on DC and T cell development and cell mediated immune responses, and their role in autoimmune disease (in collaboration with Prof Jim Johnston).  I am also investigated the role of ARF6 (GTP binding protein) in T cell activation and anergy through the use of in vitro models and the development of an ARF6 conditional knockout model.

As part of the DEL All-Ireland Research Base grant I am also collaborating with key members of the CII to establish key in vivo models of respiratory and infectious disease.  Four Home Office project licences have been written and are awaiting ethical approval to commence work with these models.