Title: Microvesicle-mediated signalling during acute lung injury: Defining the role of acid sphingomyelinase
Funder: The Academy of Medical Sciences

Abstract: Acute respiratory distress syndrome (ARDS) has significant mortality and morbidity, complicated by a lack of effective treatments. Microvesicles (MVs) are mediators of cellular communication carrying a variety of molecular cargo to target cells and play an important pathophysiological role during acute lung injury (ALI)/ARDS. Based on my preliminary data, cells lacking acid sphingomyelinase (ASM), a key cellular enzyme activated in response to a variety of cellular stresses, produced reduced numbers of MVs in vitro and those MVs were devoid of inflammatory molecular cargo embedded within them. Therefore I hypothesise that ASM plays a critical role in the pathophysiology of ALI/ARDS by generating pro-inflammatory MVs and redirecting molecular cargo within MVs for inter-cellular signalling. I aim to investigate this hypothesis focusing on three central objectives: 1. To confirm in vivo that ASM knockout (-/-) alveolar cells produce reduced number of MVs 2. To investigate biological cargo carried within MVs produced from ASM-/- alveolar cells and identify the mechanisms by which ASM is responsible for packaging cargo within MVs. 3. To determine the functional activity of MVs from ASM-/- alveolar cells and the significance of ASM in MV mediated signalling during ALI. We will utilise in vivo mouse models and in vitro cell culture experiments combining physiological, immunological and molecular methodologies. Pharmacological inhibition and genetically modified mice will be used to elucidate the physiological significance of ASM in MV production and cargo trafficking. The results will provide crucial information on MV-mediated signalling during ALI, potentially identifying novel, previously unexplored therapeutic strategies.

Lay abstract: Acute lung injury (ALI) is a life-threatening lung condition, frequently diagnosed in critically unwell patients on intensive care. Unfortunately, patients with ALI have a 40% chance of dying and those that survive have severe long-term physical and psychological problems. Therefore urgent research is needed to improve scientific knowledge of this lethal condition and identify new therapies. Microvesicles are extremely small particles released by cells and carry messages between cells. We have demonstrated that these vesicles have a fundamental role in the development of ALI, and could be a potential target for future novel therapies. However we need to understand why cells release microvesicles and how cells package their cargo within these vesicles. Acid sphingomyelinase (ASM) is a key cellular signalling molecule that is activated during cell injury or damage. It has been shown that mice that lack ASM do not develop ALI but the reasons behind this protection are currently unknown. My preliminary data demonstrate that isolated cells without ASM produced less microvesicles and these vesicles lacked an important cellular cargo key to the development of ALI. Therefore I hypothesis that ASM plays a vital role in ALI by generating microvesicles and packaging important cargo within these vesicles. We will use mice where ASM has been deleted genetically to investigate this and understand the mechanistic and functional importance of ASM. Identification of the mechanisms which generate ALI will allow development of new medicines that can modulate microvesicles and thus treat this deadly disease.

Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING;2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: RESPIRATORY