Host Defence Peptides in Diabetes Mellitus Type 2 Patients with Periodontal Disease. A Systematic Review

The aim of the study was to critically assess and review the latest evidence relating the associations between host defence peptides (HDPs), periodontal diseases (PD) and diabetes mellitus type 2 (DM2). To explore studies on HDPs, periodontal disease, and DM2, researchers utilised specific key phrases to search the electronic databases PubMed (National Library of Medicine), Embase (Ovid), Medline (EBSCO), and Dentistry and Oral Sciences (EBSCO). Quality assessment was conducted by means of the Newcastle Ottawa scale and the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool. Following a thorough screening process, a total of 12 papers (4 case-control, 6 cross-sectional, 1 animal, and 1 in vitro) fulfilled the selection criteria and were included. The majority of research found that HDPs were upregulated in DM2 patients with PD. Three investigations, however, found that HDPs were downregulated in DM2 patients with PD. HDPs play a part in the pathophysiology of PD and DM2. Nonetheless, more human, animal and laboratory investigations are needed to fully understand validation of the link, as the evidence is limited. Understanding HDPs as common moderators is critical, aimed at unlocking their potential as therapeutic and diagnostic agents.

The Role of Bovine Cathelicidins in Host Defence

<p>Cattle are constantly exposed to environmental pathogens and are susceptible to a number of diseases which cause significant economic loss or animal welfare concerns. The mucosal surface is a key barrier to infection and a greater understanding of bovine mucosal immunology may lead to improved disease management strategies. The cathelicidins are a family of host defence proteins which may play an important role in this defensive barrier. The cathelicidins are composed of a globular cathelin-like domain (CLD) and a C-terminal antimicrobial peptide (AMP) domain. The CLD is highly conserved across all species in which cathelicidins are found, yet the role of the CLD during infection has not been firmly established. The first aim of this thesis was to produce functional recombinant bovine CLD as a precursor to further experiments. However, the recombinant protein bound less lipopolysaccharide, was unable to agglutinate microbes, and was unable to permeabilise neutrophil membranes when compared to the activity of a native CLD preparation. Although further studies were not carried out with recombinant CLD, these results demonstrated that cell death induced by the native CLD and the agglutination of microbes potentially contribute to a broad anti-inflammatory role for the CLD during infection. In contrast to humans and mice where only one cathelicidin isoform is expressed, bovine express seven cathelicidins, with variable AMP domains. Therefore the second aim of this thesis was to profile the effect of bovine cathelicidin AMPs on neutrophil function. The bovine AMPs were able to modify a number of activities. Migration and reactive oxygen species (ROS) production were enhanced by several peptides while ROS production was inhibited by others. When investigated in further detail, linear Bac1 (bactenecin), Bac5 and BMAP-34 (bovine myeloid antimicrobial peptide) were able to dose-dependently induce or inhibit several key neutrophil functions including migration, degranulation, respiratory burst and phagocytosis, indicating significant roles in differential modulation of immune responses. In particular, Bac5 was able to differentially modify neutrophil respiratory burst without significant disruption to cellular homeostasis, which suggested Bac5 was acting via an intracellular mechanism. The third aim of this thesis was to investigate the mechanism by which Bac5 modulated neutrophil function. The results demonstrated the ability of Bac5 to be internalised by neutrophils and that Bac5 inhibition of p47phox binding to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is a possible explanation for the differential induction and inhibition of extracellular ROS production. β-actin was identified as a major intracellular target for Bac5 and is consistent with the ability of Bac5 to modulate multiple neutrophil functions. In summary, this thesis demonstrates that the bovine cathelicidins have multiple roles in host defence. The conserved CLD appears to have an anti-inflammatory role through an as yet undefined mechanism. The variable AMPs together have multifaceted roles which may act in concert to promote elimination of pathogens and regulate excessive detrimental neutrophil activity. The combined effect of these roles will facilitate clearance of pathogens during infection and aid in the resolution of the innate inflammatory response at mucosal surfaces.</p>

The Role of Bovine Cathelicidins in Host Defence

<p>Cattle are constantly exposed to environmental pathogens and are susceptible to a number of diseases which cause significant economic loss or animal welfare concerns. The mucosal surface is a key barrier to infection and a greater understanding of bovine mucosal immunology may lead to improved disease management strategies. The cathelicidins are a family of host defence proteins which may play an important role in this defensive barrier. The cathelicidins are composed of a globular cathelin-like domain (CLD) and a C-terminal antimicrobial peptide (AMP) domain. The CLD is highly conserved across all species in which cathelicidins are found, yet the role of the CLD during infection has not been firmly established. The first aim of this thesis was to produce functional recombinant bovine CLD as a precursor to further experiments. However, the recombinant protein bound less lipopolysaccharide, was unable to agglutinate microbes, and was unable to permeabilise neutrophil membranes when compared to the activity of a native CLD preparation. Although further studies were not carried out with recombinant CLD, these results demonstrated that cell death induced by the native CLD and the agglutination of microbes potentially contribute to a broad anti-inflammatory role for the CLD during infection. In contrast to humans and mice where only one cathelicidin isoform is expressed, bovine express seven cathelicidins, with variable AMP domains. Therefore the second aim of this thesis was to profile the effect of bovine cathelicidin AMPs on neutrophil function. The bovine AMPs were able to modify a number of activities. Migration and reactive oxygen species (ROS) production were enhanced by several peptides while ROS production was inhibited by others. When investigated in further detail, linear Bac1 (bactenecin), Bac5 and BMAP-34 (bovine myeloid antimicrobial peptide) were able to dose-dependently induce or inhibit several key neutrophil functions including migration, degranulation, respiratory burst and phagocytosis, indicating significant roles in differential modulation of immune responses. In particular, Bac5 was able to differentially modify neutrophil respiratory burst without significant disruption to cellular homeostasis, which suggested Bac5 was acting via an intracellular mechanism. The third aim of this thesis was to investigate the mechanism by which Bac5 modulated neutrophil function. The results demonstrated the ability of Bac5 to be internalised by neutrophils and that Bac5 inhibition of p47phox binding to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is a possible explanation for the differential induction and inhibition of extracellular ROS production. β-actin was identified as a major intracellular target for Bac5 and is consistent with the ability of Bac5 to modulate multiple neutrophil functions. In summary, this thesis demonstrates that the bovine cathelicidins have multiple roles in host defence. The conserved CLD appears to have an anti-inflammatory role through an as yet undefined mechanism. The variable AMPs together have multifaceted roles which may act in concert to promote elimination of pathogens and regulate excessive detrimental neutrophil activity. The combined effect of these roles will facilitate clearance of pathogens during infection and aid in the resolution of the innate inflammatory response at mucosal surfaces.</p>

Blood Compatibility of Widely used Central Venous Catheters; an Experimental Study

Background: An inserted central venous catheter (CVC) is considered foreign material by the inert host defence systems and induce inflammation and thrombus formation. The objective of this study was to evaluate blood compatibility of six commonly used CVCs.Methods: Three coated and three uncoated CVC materials were tested in a modified Chandler loop model. Each catheter material circulated in blood from ten different healthy volunteers for 1 hour. Blood cell counts and measurements of the inert host defence systems were performed on blood samples from the loop.Results: All the tested catheters demonstrated impact on blood cells, contact coagulation, the complement system, or inflammatory markers, although the impact varied significantly.Conclusions: Of the catheters we evaluated, the most unfavourable blood compatibility profile was found for the polyurethane CVC coated with chlorohexidine and silver sulfadiazine. The greatest variation in blood compatibility between test runs was noted for the silicone dialysis catheter. Poor blood compatibility should be taken seriously but given the experimental design of the current study the clinical significance remains to be evaluated.

A pro-resolving phenotype underpins the anti-inflammatory effects of inorganic nitrate

Introduction Increasing evidence highlights the critical role of chronic inflammation in cardiovascular disease (CVD). Targeting inflammatory pathways in patients with CVD has been associated with improved CV function in pre-clinical (Gee, 2017), early clinical (Yndestad, 2006; Velmurugan 2013; Jones, 2016) and large phase III studies (Ridker, 2017). The resolution of inflammation is an active process and its failure has also been proposed to contribute to CVD progression. At least one mechanism thought to underlie this failure is dysfunction of the canonical pathway for anti-inflammatory nitric oxide (NO) production. Restoring NO through provision of inorganic nitrate (NO3-) and subsequent bioactivation via the non-canonical pathway may offer therapeutic benefit. Aim To test whether dietary NO3–derived NO accelerates resolution of inflammation. Methods Randomised, double-blind, placebo-controlled, parallel limb study of 8–10mmol dietary NO3- supplementation versus NO3–deplete placebo beetroot juice in 36 healthy male volunteers (NCT03183830). Using a cantharadin-induced skin blister model (Day, 2001), acute (24h) and chronic (72h)-phase blisters were harvested pre- and post-treatment. Blister exudate was analysed for leucocyte activation state (CD11b, CD62L, CD162) by flow cytometry and cytokine/chemokine composition by ELISA. Ozone chemiluminescence established NO3-/NO2- levels in key biological matrices: plasma, urine and saliva. Results 9.3mmol inorganic NO3- led to a significant rise (versus placebo, p&lt;0.001) of NO3-/NO2- in plasma, saliva and urine NO2- (p&lt;0.02). No differences were seen in blister volumes, cell counts or markers of systemic inflammation. Whilst no differences were seen in the proportions of cellular infiltrate in 24h blisters, there were significant reductions of neutrophil (p=0.017) and intermediate monocyte proportions (p=0.001) and cellular adhesion molecules across inflammatory, intermediate and resolving monocytes at 72h (Figure 1). Generally, no differences in blister cytokine/chemokine profile was evident except for borderline significant suppression of TNFα at 24hrs with dietary NO3- treatment (P=0.057). Conclusion Whilst dietary inorganic NO3- does not impair the essential host defence response it does accelerate resolution: enhanced pro- to anti-inflammatory monocyte subtype switching and curtailed neutrophil recruitment, likely via attenuated TNFα production. These actions offer a novel, easy to administer, approach to influence inflammatory responses without impairing host defence. FUNDunding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Derek Willoughby Trust and British Heart Foundation

Airway inflammation in severe asthmatics with acid gastro-oesophageal reflux

The relationship between childhood asthma and gastro-oesophageal reflux (GOR) is contentious. Recent studies in adult asthmatics suggest that GOR is associated with worse control and differences in sputum proteomics related to epithelial integrity, systemic inflammation and host defence. We assessed 127 children with severe asthma undergoing bronchoscopy and pH study. There were no differences in asthma control or measures of airway inflammation or remodelling when those with acid GOR were compared with those without. These results suggest that acid GOR is not an important comorbidity in paediatric severe asthma.