Impact of Tetracycline Antibiotics on Skeletal Maturation

四环素抗生素对骨骼成熟的影响

• 批准号: 10660594
• 负责人: Caroline Westwater
• 金额: $ 53.21万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2028-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10660594
• 关键词: Accounting; Acne; Adolescence; Adolescent; Affect; Age; Agonist; Animals; Antibiotics; Attenuated; Bacteria; Bile Acid Biosynthesis Pathway; Bile Acids; C57BL/6 Mouse; CYP7A1 gene; Cell physiology; Circulation; Development; Distant; Dose; Doxycycline; Endocrine; Enterocytes; Euthanasia; Excretory function; FGFR4 gene; Fibroblast Growth Factor; Fracture; Germ-Free; Hepatic; Hepatocyte; High Prevalence; Homeostasis; Hydrolase; Impairment; In Situ; Indigenous; Intestines; Knockout Mice; Life; Liver; Mediating; Metagenomics; Minocycline; Mus; Osteoblasts; Osteogenesis; Osteopenia; Osteoporosis; Phase; Phenotype; Production; Publishing; Reporting; Research; Resistance; Role; Serum; Signal Transduction; Site; Skeleton; Tamoxifen; Testing; Tetracyclines; Work; antagonist; bacteriome; bile salts; bone; bone cell; bone health; bone mass; bone metabolism; clinically relevant; critical developmental period; dysbiosis; fecal microbiota; fexaramine; fracture risk; germ free condition; gut bacteria; gut dysbiosis; gut microbes; gut microbiota; in vivo; inhibitor; mechanical properties; microbiota; novel; osteoclastogenesis; skeletal; skeletal maturation

PROJECT SUMMARY/ABSTRACT Roughly 1/3 of bone mass accrual during life is realized during adolescence. Disruption of this critical window of skeletal maturation has lifelong implications for bone health and fracture risk. Systemic tetracyclines (i.e., minocycline, doxycycline) are commonly used to treat acne in adolescents, but the impact on bone is unclear. Preliminary studies were performed treating C57BL/6 mice with a clinically relevant dose of doxycycline or minocycline during pubertal/postpubertal development. Administering doxycycline or minocycline to specific- pathogen-free (SPF) mice caused dysbiotic shifts in the gut bacteriome and impaired skeletal maturation. Administering minocycline to mice reared under germ-free (GF) conditions did not affect the skeletal phenotype, which supports that tetracyclines’ effects on the maturing skeleton depend on the gut microbiota. Bile acids were identified as a novel candidate regulator contributing to gut microbiota effects on bone metabolism. Bile acids are synthesized in the liver and excreted into the intestine, where bacteria metabolize them. The intestinal FXR-FGF15 axis is a gut-liver endocrine axis that supports bile acid homeostasis. Bile acid activation of enterocyte-FXR induces the production of FGF15, which signals at hepatocyte-FGFR4 to inhibit CYP7A1- mediated bile acid synthesis. Bacteria have unique bile salt hydrolases (BSHs) that differentially deconjugate bile acids. Conjugation status affects bile acids’ potential to activate FXR. Shifts in intestinal bacteria composition alter BSHs' deconjugation of bile acids, which can disrupt the intestinal FXR-FGF15 axis. Preliminary studies showed that minocycline treatment blunted ileal FGF15 and enhanced hepatic Cyp7a1, which implies tetracyclines disrupt the intestinal FXR-FGF15 axis. Minocycline increased serum bile acids that are FXR antagonists, and this altered bile acid profile attenuated osteogenesis in cultured primary osteoblasts. Two aims will test the overall hypothesis: Tetracycline-induced gut dysbiosis disrupts the intestinal FXR- FGF15 axis, which impairs skeletal maturation through dysregulated serum bile acids that attenuate osteoblast- FXR signaling or reduced serum FGF15 activation of osteoblast-FGFR4 signaling. Aim 1 will utilize metagenomic approaches and fecal microbiota transfer from SPF to GF mice. Studies will delineate how minocycline- and doxycycline-induced changes in gut bacteria alter the transformation of intestinal bile acids to affect the FXR- FGF15 axis. Aim 2 relies on administering an intestinal-specific FXR agonist to define the role of the FXR-FGF15 axis in minocycline effects on the skeleton. Tamoxifen inducible osteoblast null mice will be used to delineate the role of osteoblast-FXR / osteoblast-FGFR4 in minocycline’s actions suppressing osteogenesis. The proposed work will define the relationship between tetracycline-induced gut dysbiosis, the FXR-FGF15 axis, osteoblast- FXR/FGFR4 signaling, and skeletal maturation. Adolescents are commonly prescribed systemic antibiotics for acne, and >70% receive tetracyclines. Gut and liver conditions have a higher prevalence of osteopenia / osteoporosis, which underscores the need to define the role of bile acids in gut microbiota effects on bone.

项目概要/摘要 一生中大约 1/3 的骨量增长是在青春期实现的。破坏这个关键窗口 骨骼成熟对骨骼健康和骨折风险具有终生影响。全身性四环素类药物（即 米诺环素、强力霉素）常用于治疗青少年痤疮，但对骨骼的影响尚不清楚。 进行了初步研究，用临床相关剂量的强力霉素或 青春期/青春期后发育期间的米诺环素。对特定人群施用多西环素或米诺环素 无病原体（SPF）小鼠会导致肠道细菌群发生菌群失调并损害骨骼成熟。 对无菌（GF）条件下饲养的小鼠施用米诺环素不会影响骨骼表型， 这支持四环素对成熟骨骼的影响取决于肠道微生物群。胆汁酸是 被确定为一种新型候选调节剂，有助于肠道微生物群对骨代谢的影响。 胆汁酸在肝脏中合成并排泄到肠道中，在那里细菌将其代谢。这 肠道 FXR-FGF15 轴是支持胆汁酸稳态的肠道-肝脏内分泌轴。胆汁酸活化 肠上皮细胞-FXR 诱导 FGF15 的产生，FGF15 向肝细胞-FGFR4 发出信号以抑制 CYP7A1- 介导胆汁酸合成。细菌具有独特的胆汁盐水解酶 (BSH)，可以差异化解偶联 胆汁酸。结合状态影响胆汁酸激活 FXR 的潜力。肠道细菌组成的变化 改变 BSH 对胆汁酸的解结合，从而破坏肠道 FXR-FGF15 轴。 初步研究表明，米诺环素治疗会减弱回肠 FGF15 并增强肝脏 Cyp7a1， 这意味着四环素会破坏肠道 FXR-FGF15 轴。米诺环素增加血清胆汁酸， 是 FXR 拮抗剂，胆汁酸谱的改变减弱了培养的原代成骨细胞的成骨作用。 有两个目标将检验总体假设： 四环素诱导的肠道菌群失调会破坏肠道 FXR- FGF15 轴，通过血清胆汁酸失调削弱成骨细胞，从而损害骨骼成熟 FXR 信号传导或降低成骨细胞 FGFR4 信号传导的血清 FGF15 激活。目标 1 将利用宏基因组 方法和粪便微生物群从 SPF 小鼠转移到 GF 小鼠。研究将描述米诺环素和 多西环素诱导的肠道细菌变化改变肠道胆汁酸的转化，从而影响 FXR- FGF15 轴。目标 2 依靠施用肠道特异性 FXR 激动剂来定义 FXR-FGF15 的作用 米诺环素对骨骼的影响轴。他莫昔芬诱导成骨细胞缺失小鼠将用于描绘 成骨细胞-FXR / 成骨细胞-FGFR4 在米诺环素抑制成骨作用中的作用。拟议的 这项工作将明确四环素诱导的肠道菌群失调、FXR-FGF15 轴、成骨细胞- FXR/FGFR4 信号传导和骨骼成熟。青少年通常会接受全身性抗生素治疗 痤疮，>70% 接受四环素治疗。肠道和肝脏疾病导致骨质减少的患病率较高/ 骨质疏松症，这强调需要确定胆汁酸在肠道微生物群对骨骼影响中的作用。