Trauma is a leading cause of death worldwide with 5.8 million deaths occurring yearly. Almost 40% of trauma deaths are due to bleeding and occur in the first few hours after injury. Of the remaining severely injured patients up to 25% develop a dysregulated immune response leading to multiple organ failure (MOF). Despite improvements in trauma care, the morbidity and mortality of this condition remains very high. Massive traumatic injury can overwhelm endogenous homeostatic mechanisms even with prompt treatment. The underlying mechanisms driving MOF are also not fully elucidated. As a result, successful therapies for trauma-related MOF are lacking. Trauma causes tissue damage that releases a large number of endogenous damage-associated molecular patterns (DAMPs). Mitochondrial DAMPs released in trauma, such as mitochondrial DNA (mtDNA), could help to explain part of the immune response in trauma given the structural similarities between mitochondria and bacteria. MtDNA, like bacterial DNA, contains an abundance of highly stimulatory unmethylated CpG DNA motifs that signal through Toll-like receptor (TLR)-9 to produce inflammation. MtDNA has been shown to be highly damaging when injected into healthy animals causing acute organ injury to develop. Elevated circulating levels of mtDNA have been reported in trauma patients but an association with clinically meaningful outcomes has not been established in a large cohort. The first aim of this PhD thesis was to determine whether mtDNA released after trauma haemorrhage is sufficient for the development of MOF. Secondly, I then aimed to determine the extent of mtDNA release with varying degrees of tissue injury and haemorrhagic shock in a clinically relevant rodent model. My final aim was to determine whether neutralising mtDNA at a clinically relevant time point in vivo would reduce the severity of organ injury in this model.

Final publication is available at http://ajp.amjpathol.org/ / 京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19583号 / 医博第4090号 / 新制||医||1014(附属図書館) / 32619 / 京都大学大学院医学研究科医学専攻 / (主査)教授 小池 薫, 教授 中山 健夫, 教授 福田 和彦 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

<p dir="ltr">Wound healing is a complex biological process orchestrated by intricate cellular and biochemical interactions. This study leverages a multiscale modeling approach, integrating agent-based and ordinary differential equation (ODE) methods within CompuCell3D, to investigate wound detection and calcium signaling in juvenile zebrafish. Calcium as a ubiquitous secondary messenger plays a crucial role in translating wound stimuli into cellular responses. We focus on the initial phase of wound detection, a multi-step process beginning at the subcellular level with the release of Damage-Associated Molecular Patterns (DAMPs) and subsequent calcium signaling. We hypothesize that an ATP diffusion wave acts as the primary trigger, initiating a downstream calcium signaling cascade mediated by inositol triphosphate (IP3). Calcium and IP3 production and movement from the injured cells to healthy ones would then coordinate a tightly regulated wound response. To investigate this hypothesis, we adapted existing equations from a Drosophila wing disc injury model. We carefully modified them to accurately represent the zebrafish system in our in-silico setup, specifically focusing on relevant agonists. Model predictions were rigorously compared to the zebrafish’s experimental data to validate the computational approach. Our findings provide preliminary evidence suggesting that ATP diffusion through the interstitial spaces of injured tissue may be a potent agonist, triggering localized calcium release closely resembling experimental observations. This multiscale modeling framework offers a promising avenue for significant advancements in wound healing research. It has the potential to facilitate the development of novel therapeutic strategies and discoveries by enabling the integration of cell signaling pathways and tissue engineering.</p>