Collaborative Research: Macrophages: Guardians of amphibian skin antifungal defenses

合作研究：巨噬细胞：两栖动物皮肤抗真菌防御的守护者

• 批准号: 2147466
• 负责人: Leon Grayfer
• 金额: $ 67.76万
• 依托单位: George Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147466&HistoricalAwards=false
• 关键词: Collaborative; Research; Macrophages; Guardians; amphibian

Fungal infections are a growing wildlife concern because of their devastating effects on biodiversity and ecosystem health. For example, the chytrid fungus, Batrachochytrium dendrobatidis (Bd) infects amphibian skin resulting in the disease chytridiomycosis, which is a leading cause of worldwide amphibian declines and extinctions. Due to its recent appearance, broad host range, and continuing spread into new geographic areas, Bd is regarded as an emerging pathogen. Swimming Bd zoospores colonize the keratinized skin of adult amphibians and the keratinized mouthparts of tadpoles. These invading zoospores develop into urn-shaped zoosporangia in which new zoospores develop and swim out to infect other areas of the skin or new hosts. Unlike other fungal infections that progress to distal organs, Bd remains confined to the skin, causing death by interfering with the essential ion transport across the skin, thereby leading to cardiac arrest. As macrophage-lineage cells, such as Langerhans cells, are integral to skin surveillance and the ensuing immune responses, these cells are undoubtedly important to the antifungal defenses against the skin-localized Bd infections. In turn, the differentiation and functionality of all vertebrate macrophages depend on the colony-stimulating factor-1 receptor (CSF-1R), which is ligated by CSF-1 and the unrelated interleukin-34 (IL-34) cytokines. We previously showed that the Xenopus laevis frog macrophages differentiated by recombinant (r)CSF-1 and rIL-34 possess markedly distinct capacities to recognize and respond to various pathogens. Through these NSF-funded studies, we will examine how these functionally dichotomous frog macrophage subsets contribute to frog Bd susceptibility and resistance. This project will incorporate students at all levels, the PIs will host annual workshops that explore the challenges and opportunities for women and minorities in sciences and public attention will be drawn to the growing threat of Bd through pedagogy and a new collaborative website.The differentiation of Langerhans cells depends on IL-34 while the roles of CSF-1 in these processes remain to be fully defined. Pertinently, enriching X. laevis skin CSF-1-macrophages results in greater Bd susceptibility whereas frogs with more skin IL-34-macrophages exhibit significantly greater resistance against this pathogen. As such, the central hypothesis guiding our studies is that an effective immune response to Bd in the skin depends on an “alarm response” from chytrid-invaded skin cells, which in conjunction with IL-34-macrophages, results in recruitment of other effectors. Conversely, an impaired frog immune response to Bd stems from failure of the skin-resident macrophages and skin epithelial cells to mount appropriate responses due to the production of immunosuppressive factors by the fungus, the infected keratinocytes, and/or resident CSF-1-macrophages. The objectives of our studies are: to define the interactions between amphibian macrophage subsets and Bd; to define the effects of Bd on the interactions between frog macrophages and lymphocytes; and to define the cellular interactions within the frog skin in the context of Bd infections. The in-depth understanding of immune interactions between frog macrophages and Bd granted by our studies, will provide a much-needed perspective into the effectiveness and limitations of the frog immune responses to this deadly fungus.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

真菌感染因其对生物多样性和生态系统健康的破坏性影响而日益受到野生动物的关注。例如，壶菌（Batrachochytrium dendroatidis, Bd）感染两栖动物的皮肤，导致壶菌病，这是世界范围内两栖动物数量下降和灭绝的主要原因。由于其最近出现，宿主范围广泛，并继续传播到新的地理区域，因此被认为是一种新兴病原体。游动的游动孢子寄生在成年两栖动物角质化的皮肤和蝌蚪角质化的口器上。这些入侵的游动孢子发育成瓮状的游动孢子囊，新的游动孢子在其中发育并游出，感染皮肤的其他部位或新的宿主。与其他进展到远端器官的真菌感染不同，Bd仍然局限于皮肤，通过干扰皮肤上必需的离子运输而导致死亡，从而导致心脏骤停。巨噬细胞谱系细胞，如朗格汉斯细胞，是皮肤监测和随后的免疫反应中不可或缺的一部分，这些细胞无疑对皮肤局限性Bd感染的抗真菌防御很重要。反过来，所有脊椎动物巨噬细胞的分化和功能依赖于集落刺激因子-1受体（CSF-1R），该受体由CSF-1和不相关的白细胞介素-34 （IL-34）细胞因子连接。我们之前的研究表明，重组(r)CSF-1和rIL-34分化的非洲爪蟾巨噬细胞具有明显不同的识别和应答各种病原体的能力。通过这些nsf资助的研究，我们将研究这些功能上分二的青蛙巨噬细胞亚群如何影响青蛙对Bd的易感性和抗性。该项目将包括各级学生，pi将举办年度研讨会，探讨妇女和少数民族在科学领域面临的挑战和机遇，并通过教学法和一个新的合作网站将公众的注意力吸引到Bd日益增长的威胁上。朗格汉斯细胞的分化依赖于IL-34，而CSF-1在这些过程中的作用仍未完全确定。相应的，丰富的黄颡鱼皮肤csf -1巨噬细胞导致更大的Bd敏感性，而皮肤il -34巨噬细胞更多的青蛙对这种病原体表现出更大的抵抗力。因此，指导我们研究的中心假设是，皮肤中对Bd的有效免疫反应取决于来自壶菌入侵皮肤细胞的“警报反应”，该反应与il -34巨噬细胞一起，导致其他效应物的募集。相反，由于真菌、受感染的角质形成细胞和/或常驻的csf -1巨噬细胞产生免疫抑制因子，导致皮肤巨噬细胞和皮肤上皮细胞无法产生适当的反应，从而导致青蛙对Bd的免疫反应受损。我们研究的目的是：确定两栖动物巨噬细胞亚群与Bd之间的相互作用；确定Bd对青蛙巨噬细胞与淋巴细胞相互作用的影响；以及在蛙类感染的背景下定义蛙类皮肤内的细胞相互作用。通过我们的研究，深入了解青蛙巨噬细胞与Bd之间的免疫相互作用，将为青蛙对这种致命真菌的免疫反应的有效性和局限性提供一个急需的视角。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Amphibian myelopoiesis

• DOI: 10.1016/j.dci.2023.104701
• 发表时间: 2023-05-18
• 期刊: DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY
• 影响因子: 2.9
• 作者: Yaparla，Amulya;Stern，David B.;Grayfer，Leon
• 通讯作者: Grayfer，Leon