Identification of novel innate immune mechanisms regulating inflammation in the gastrointestinal tract

The Gastro-Intestinal (GI) tract is a unique region in the body. Our innate immune system retains a fine homeostatic balance between avoiding inappropriate inflammatory responses against the myriad commensal microbes residing in the gut while also remaining active enough to prevent invasive pathogenic attack. The intestinal epithelium represents the frontline of this interface. It has long been known to act as a physical barrier preventing the lumenal bacteria of the gastro-intestinal tract from activating an inflammatory immune response in the immune cells of the underlying mucosa. However, in recent years, an appreciation has grown surrounding the role played by the intestinal epithelium in regulating innate immune responses, both in the prevention of infection and in maintaining a homeostatic environment through modulation of innate immune signalling systems. The aim of this thesis was to identify novel innate immune mechanisms regulating inflammation in the GI tract. To achieve this aim, we chose several aspects of regulatory mechanisms utilised in this region by the innate immune system. We identified several commensal strains of bacteria expressing proteins containing signalling domains used by Pattern Recognition Receptors (PRRs) of the innate immune system. Three such bacterial proteins were studied for their potentially subversive roles in host innate immune signalling as a means of regulating homeostasis in the GI tract. We also examined differential responses to PRR activation depending on their sub-cellular localisation. This was investigated based on reports that apical Toll-Like Receptor (TLR) 9 activation resulted in abrogation of inflammatory responses mediated by other TLRs in Intestinal Epithelial Cells (IECs) such as basolateral TLR4 activation. Using the well-studied invasive intra-cellular pathogen Listeria monocytogenes as a model for infection, we also used a PRR siRNA library screening technique to identify novel PRRs used by IECs in both inhibition and activation of inflammatory responses. Many of the PRRs identified in this screen were previously believed not to be expressed in IECs. Furthermore, the same study has led to the identification of the previously uncharacterised TLR10 as a functional inflammatory receptor of IECs. Further analysis revealed a similar role in macrophages where it was shown to respond to intracellular and motile pathogens such as Gram-positive L.monocytogenes and Gram negative Salmonella typhimurium. TLR10 expression in IECs was predominantly intracellular. This is likely in order to avoid inappropriate inflammatory activation through the recognition of commensal microbial antigens on the apical cell surface of IECs. Moreover, these results have revealed a more complex network of innate immune signalling mechanisms involved in both activating and inhibiting inflammatory responses in IECs than was previously believed. This contribution to our understanding of innate immune regulation in this region has several direct and indirect benefits. The identification of several novel PRRs involved in activating and inhibiting inflammation in the GI tract may be used as novel therapeutic targets in the treatment of disease; both for inducing tolerance and reducing inflammation, or indeed, as targets for adjuvant activation in the development of oral vaccines against pathogenic attack.

Clinical autonomy and nurse/physician collaboration in emergency nurses

Aim: To investigate clinical autonomy and Nurse/Physician collaboration among emergency nurses and the relationship between these concepts, personal characteristics and organisational influences. Background: Nurses have been identified as having a significant role in addressing the challenges of providing modern healthcare. Emergency nurses have reported competence in a wide range of emergency care skills. However, there is evidence that Emergency Department (ED) nurses may have lower levels of clinical autonomy than other areas of practice. Levels of clinical autonomy appear to be influenced by levels of collaboration with physicians and the organisations in which nurses work Methods: A descriptive correlational study using a survey design with a purposive convenience sample of 141 ED staff nurses (response 70.9%) from 3 EDs in Ireland. Data were collected using the Dempster Practice Behaviours Scale (DPBS) the Nurse/Physician Collaboration Scale (NPCS) and the newly developed Organisational Influences on Nursing Scale. Demographic information was also sought from participants. Results: Participants were largely female (87%), relatively young (mean age 35.57, SD=7.83) and educated to degree level (48%) or higher (31%) with 40% posessing specialist emergency nursing qualifications. Participants reported moderate levels of clinical autonomy and Nurse/Physician collaboration. No relationships were found between sample characteristics and clinical autonomy and Nurse/Physician collaboration among emergency nurses. Relationships were found between levels of clinical autonomy and Nurse/Physician collaboration (r=-0.395, n=100, p<0.001), and organisational influence on nursing (r=0.455, p<0.001) and also between Nurse/Physician collaboration and organisational influence on nursing (r=-0.413, p<0.001). Discussion: Clinical autonomy of nurses has been linked with quality outcomes in healthcare. The quest for quality in modern healthcare in a challenging environment should acknowledge that strategies need to focus beyond education and skills provision and include essential elements such as Nurse/Physician collaboration and the organisational influence on nursing to ensure the greater involvement of nurses in patient care.