Early in the project, we asked Mr Guo about the current status of using intestinal microbiota to heal autoimmune diseases, and verified the novelty of our project. At a later stage of the project, to ensure the biosafety, we aimed to design a suicide system in yeast. We sought a special intestinal marker, and the trigger of suicide when yeast loss the sense of this marker. We asked for Dr Guo Xiaohuan's suggestion, who is a professional in intestinal immunology and microbiota. He guided us to find metabolites of microbiota and other intestinal factors, and we eventually chose bile acid as the suicide marker.
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<p><strong>Who</strong><br>
Guo Xiaohuan, Research Fellow, Ph.D. Supervisor, and Associate Professor of the School of Medicine, Tsinghua University. He has long been engaged in the study of intestinal mucosal immunity and intestinal flora regulation, and has elucidated the mechanism of action of intestinal flora and its metabolites affecting intestinal infections, inflammation as well as the efficacy of anti-tumor therapy.
<p><strong>Why</strong><br>
After we decided on healing autoimmune disease with intestinal flora, we wanted to learn more about the current state of this kind of treatment in the medical field. Since Dr Guo Xiaohuan is an expert in intestinal flora and immunity, we emailed him for consultation.</p>
<p>In Dr Guo's reply, he indicated that clinical studies on the use of intestinal flora to heal autoimmune diseases had not yet been seen, nor had cures been reported at the mouse level. We were exploring an innovative field. He also expressed concerns about the viability of the project, pointing out a number of challenges. In fact, we were not trying to completely cure IBD through intestinal flora, but achieving relief from IBD symptoms in an enjoyable and convenient way, which we were confident to accomplish through concrete design. After talking to Dr Guo, we were clear about the direction of our project.</p>
<p>Later in the project, in addition to the nutrient-deficient type, we felt the necessity to design suicide system to ensure biosafety. This would require an intestine-specific marker-when the yeast cannot detect this marker, it indicates that it has left the intestinal environment and needs to activate the suicide system. We were at a loss when searching for the intestinal marker, so we sent an email to consult Dr Guo again. </p>
<p>Dr Guo replied to us with patience. He first guided us to clarify the issue, whether we were looking for markers of the contents or the intestinal tissue, and recommended a literature “Targeted delivery of the probiotic Saccharomyces boulardii to the extracellular matrix enhances gut residence time and recovery in murine colitis”. After we determined that we needed markers of the content, he suggested some metabolites of microbiota and factors secreted by the intestinal tract, and reminded us to pay attention to the sensitivity of the sensing. In the end, we chose bile acids as our intestinal marker, and the yeast would activate the suicide system when it could not detect bile acids.</p>
<p>Throughout the course of our project, Dr Guo offered a wealth of professional and authoritative insights, which greatly enhanced the scientific rationality of our entire project design.</p>
Challenges in drylab initially included establishing a model to validate the process of muscone diffusion in body. Valuable insights from Liang Xin, the professor of physiology in the School of Life Sciences, inspired us to seek the blood concentration of muscone and the knowledge of pharmacokinetics.
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<p><strong>Who</strong><br>
Liang Xin, Associate Professor of School of Life Sciences, Tsinghua University.
<p><strong>Why</strong><br>
A critical aspect of the rationality of our project is to demonstrate that inhaling muscone can elevate the concentration of muscone in the intestines to a level that activates the yeast signaling pathway, meaning that muscone can effectively diffuse into the intestine. However, due to the inability to conduct animal experiments, this must be verified through modeling. Initially, on the WeChat, we consulted Dr Liang, who teaches physiology, to assess the possibility of muscone diffusing into the intestines.</p>
<p>After carefully listening to our ideas, Dr Liang offered several points of caution. First, we need to consider the pathways by which gases might diffuse into the intestines before proceeding with further calculations. Additionally, we should clarify the advantages of muscone inhalation compared to other therapies. In terms of advice, Dr Liang suggested that if quantitative calculations was challenging, we could estimate based on blood concentration reported in the literature—hydrophobic molecules could cross cell membranes, and their concentration in the small intestine might be similar to that in the blood vessels. </p>
<p>Dr Liang's insights were illuminating in our initial drylab experiments. We began to conceptualize the uniqueness of inhalational therapy and meticulously analyze the various pathways through which gas diffusion could occur, which allowed us to refine our understanding of how the therapy might work and to identify the key factors that needed to be considered in our research.</p>
