Bovine respiratory disease complex (BRDC) is a multifactorial disease of cattle which presents as bacterial and viral pneumonia. The causative agents of BRDC work in synergy to suppress the host immune response and increase the colonisation of the lower respiratory tracts by pathogenic bacteria. Environmental stress and/or viral infection predispose cattle to secondary bacterial infections via suppression of key innate and adaptive immune mechanisms. This allows bacteria to descend the respiratory tract unchallenged. BRDC is the costliest disease among feedlot cattle, and whilst vaccines exist for individual pathogens, there is still a lack of evidence for the efficacy of these vaccines and uncertainty surrounding the optimum timing of delivery. This review outlines the immunosuppressive actions of the individual pathogens involved in BRDC and highlights the key issues in the development of vaccinations against them.

E-cigarettes are a highly popular nicotine replacement therapy in the process of smoking cessation. Despite this, research on the effects of E-vapours to human health remains limited. The popularity of vaping and mass production of cheap E-liquids has led to compromised safety regulations, with contaminants such as heavy metals and alkaloids detected in multiple liquids. Vaporised E-liquids increase cellular ROS generation and inflammatory cytokine release from pulmonary macrophages. This suggests that E-cigarette usage might activate inflammasomes. Common food additives vegetable glycerine (VG) and propylene glycol (PG) form the base of all E-liquids, but little is known about their inflammatory potential once inhaled. Here, the effect of PG and VG on inflammasome activation and cytokine release was investigated in macrophages and epithelial cells exposed to E-liquids and vaporised E-liquid extract (E-vapour). Base E-liquid and E-vapour did not induce cellular cytotoxicity and non-vapourised E-liquid had no effect on IL-8 release. However, basic PG/VG E-vapour inhibited both IL-8 release and conventional inflammasome activation by known inflammatory activators in macrophages and epithelial cells. These results propose a novel inhibitory effect of basic E-vapour components to inflammatory challenges.

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