Fat and bone: the multiperspective analysis of a close relationship

Abstract

The study of bone has for many years been focused on the study of its mineralized component, and one of the main objects of study as radiology developed as a medical specialty. The assessment has until recently been almost limited to its role as principal component of the scaffolding of the human body. Bone is a very active tissue, in continuous cross-talk with other organs and systems, with functions that are endocrine and paracrine and that have an important involvement in metabolism, ageing and health in general. Bone is also the continent for the bone marrow, in the form of "yellow marrow" (mainly adipocytes) or "red marrow" (hematopoietic cells and adipocytes). Recently, numerous studies have focused on these adipocytes contained in the bone marrow, often referred to as marrow adipose tissue (MAT). Bone marrow adipocytes do not only work as storage tissue, but are also endocrine and paracrine cells, with the potential to contribute to local bone homeostasis and systemic metabolism. Many metabolic disorders (osteoporosis, obesity, diabetes) have a complex and still not well-established relationship with MAT. The development of imaging methods, in particular the development of cross-sectional imaging has helped us to understand how much more laid beyond our classical way to look at bone. The impact on the mineralized component of bone in some cases (e.g., osteoporosis) is well-established, and has been extensively analyzed and quantified through different radiological methods. The application of advanced magnetic resonance techniques has unlocked the possibility to access the detailed study, characterization and quantification of the bone marrow components in a non-invasive way. In this review, we will address what is the evidence on the physiological role of MAT in normal skeletal health (interaction with the other bone components), during the process of normal aging and in the context of some metabolic disorders, highlighting the role that imaging methods play in helping with quantification and diagnosis.

Osteoporosis and osteoblasts cocultured with adipocytes inhibit osteoblast differentiation by downregulating histone acetylation

“…Hu et al, 2018). Considering that the adipose tissue from bone marrow contains a heterogeneous cell population that may be affected by several pathophysiological conditions with consequences to the function of adipocytes (AparisiGómez et al, 2020), the extrapolation of our results to all these situations is complex, as, in our study, the adipocytes had differentiated from the adipose tissue MSCs of healthy animals. Additionally, it remains to be determined whether the osteoblast modifications induced by adipocytes significantly contribute to the bone loss in osteoporosis, if these modifications are permanent, and by what means can these modifications be reverted.…”

Distinct Shades of Adipocytes Control the Metabolic Roles of Adipose Tissues: From Their Origins to Their Relevance for Medical Applications

“…Indeed, bone marrow adipocytes (BM-adipocytes) appear as negative regulators of hematopoiesis by promoting quiescence of progenitor cells [38]. This tissue increases with age and people with prevalent vertebral fractures display higher mean BM-AT [39]. As for the other fat depots; human BM-adipocytes depots secrete adipokines [40].…”

The results of immunohistochemical study of antibodies to CYP11B2 in primary hyperaldosteronism

“…В течение долгого времени предполагалось, что КМАД является исключительно негативным регулятором остеосинтеза и гемопоэза. Увеличение объема КМЖТ зачастую ассоциировано со снижением минеральной плотности костной ткани и повышением риска переломов у людей пожилого возраста [71]. У животных при ожирении и старении повышение содержания костномозговой жировой ткани сопровождается нарушением функции ГСК и МСК [14].…”

“…В отличие от подкожной жировой ткани, экспансия КМЖТ на фоне избыточного питания не сопровождается повышением экспрессии провоспалительных генов; инфильтрации макрофагами, развития фиброза и инсулинорезистентности не наблюдается [60,81]. Учитывая инвазивность процедуры костной биопсии, изучение КМЖТ у человека в основном проводится с помощью МРТ, КТ либо ПЭТ/КТ [71]. Оценка взаимосвязи между ИМТ и состоянием КМЖТ у людей началась сравнительно недавно.…”