Mechanochemical interplay between Extracellular Matrix and cellular responses in Idiopathic Pulmonary Fibrosis (Ref: 4659)

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Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with a median survival of only 3-5 years after diagnosis - a prognosis worse than many cancers. Normal lung is irreversibly replaced by scar tissue, which makes breathing progressively more difficult. Around 32,000 people in the UK are estimated to have IPF, with 6,000 new cases estimated to occur annually - and it is responsible for >1% of all UK deaths.Lung cell behaviour is influenced by a tissue-specific macromolecular structure called the extracellular matrix (ECM), which gives tissues physical support and is crucial to healthy organ function. However, an excessive accumulation of ECM and remodelling of the lung architecture is a pathological characteristics of IPF. Changes to the biomechanical properties of the fibrotic ECM, such as increased tissue stiffness, may affect the quantity of pro-fibrotic growth factors available to cells, their behaviours, and how phenotypes are determined. For instance, ECM substrate stiffness greater than 8 kPA may cause fibroblast contractility, cytoskeletal changes, ECM secretion, and differentiation of fibroblasts to myofibroblasts - the central effector cell in IPF. However, the specific interactions between the ECM elements and the processes that cause fibrosis to occur in the majority of individuals are still poorly understood. The word "matrisome" has been coined to characterise the constituents found in the tissue ECM, which include fibrillar proteins, glycoproteins, proteoglycans, and their associated modifying agents (such as metalloproteases and matricellular proteins).Current guidelines for diagnosing IPF are based on a high-resolution computed tomography (CT) findings and occasionally on the histological analysis of a lung biopsy for confirmation of diagnosis. Histology is also essential in pathophysiological investigations of experimental samples, allowing investigation of microstructure. A growing, multidisciplinary area of label-free optical technologies offers the inherent benefit of avoiding the laborious steps of traditional histology, with the added possibility of in-vivo use (e.g. via bronchoscopy), to overcome these limitations. Label-free technologies are especially promising for multimodal platforms since they do not need artificial contrast agents that might interfere with other integrated measurement methods.The study of intact, unstained tissue using multiphoton microscopy (MPM), which relies on endogenous sources of nonlinear signals, is gaining popularity in the fields of biomedicine and bioengineering. In particular, the intrinsic second harmonic generation (SHG) of fibrillar collagen can be observed in tandem with cellular and extracellular 2-Photon Excited Fluorescence (2PEF) endogenous signals, allowing researchers to explore the ECM macromolecular architecture. The polarisation sensitive SHG microscopy can image structure and composition at the microscopic scale, and report a measure of organisation at the molecular scale. Raman spectroscopy (RS) is another label-free spectroscopic method that permits in-depth investigation of the biochemical of materials by using the inelastic scattering of photons by molecules with discrete rotational or vibrational energy links. How the precise mechanochemical properties of the ECM can influence cellular behaviour in IPF is not well understood. It is also unclear whether the altered phenotype of disease fibroblasts can directly modify the ECM to propagate pathology. This research will add to our understanding of the ECM features that influence lung fibroblast behaviour and how this interaction works, with a focus on mechano-transduction signalling.The project Aim is therefore to investigate the bi-directional mechanochemical relationship between the extracellular matrix and lung fibroblasts in the context of IPF using tissue samples, organoids, multiphoton microscopy and Raman spectroscopy.