Characteristics of mesenteric adipose tissue attached to different intestinal segments and their roles in immune regulation

Abstract

Background: Mesenteric adipose tissue (MAT) plays a critical role in the intestinal physiological ecosystems. Small and large intestines have evidently intrinsic and distinct characteristics. However, whether there exist any mesenteric differences adjacent to the small and large intestines (SMAT and LMAT) has not been properly characterized. We studied the important facets of these differences, such as morphology, gene expression, cell components and immune regulation of MATs, to characterize the mesenteric differences. Methods: The SMAT and LMAT of mice were utilized for comparison of tissue morphology. Paired mesenteric samples were analyzed by RNA-seq to clarify gene expression profiles. MAT partial excision models were constructed to illustrate the immune regulation roles of MATs, and 16S-seq was applied to detect the subsequent effect on microbiota. Results: Our data show that different segments of mesenteries have different morphological structures. SMAT not only has smaller adipocytes but also contains more fat-associated lymphoid clusters than LMAT. The gene expression profile is also discrepant between these two MATs in mice. B-cell markers were abundantly expressed in SMAT, while development-related genes were highly expressed in LMAT. Adipose-derived stem cells of LMAT exhibited higher adipogenic potential and lower proliferation rates than those of SMAT. In addition, SMAT and LMAT play different roles in immune regulation and subsequently affect microbiota components. Finally, our data clarified the described differences between SMAT and LMAT in humans. Conclusions: There were significant differences in cell morphology, gene expression profiles, cell components, biological characteristics, and immune and microbiota regulation roles between regional MATs.

The Metabolic Syndrome, a Human Disease

“…The masses of WAT tend to differentiate and occupy body spaces in which their presence causes only limited functional problems (or where their mechanical/thermic buffering becomes an asset), and are correlated with the massive presence of intracellular fat depots and the presence, but also of interspersed cells or small groups of WAT cells within a number of organs and tissues, such as the muscle: intramuscular [753][754][755], pericardial [756], perivascular [757,758]; other specialized tissues, bone marrow [759,760], or mammary tissue [761]; as well as surrounding them for physical/thermal protection, nurture, and regulation: perigonadal [762,763], subcutaneous [764][765][766], perirenal [767], and mesenteric [768,769] adipose tissues. The location and close relationship with specific organs, sharing contact and direct metabolic and humoral-regulatory connections, result in a high level of sub-specialization in both cell composition, depot size, and metabolic activity [770][771][772]. There has been considerable discussion on the pathogenic significance of their gross excess of energy, which is finally converted into adipocyte depots in the form of defined WAT masses, and of groups of adipocytes interspersed with other tissue cells in organs and tissues.…”

A New Organ: The Mesentery and Non-Vascular Mesenteric Diseases

“…Mesenteric fat contains white adipose tissue and plays a significant role in maintaining energy homeostasis and intestinal physiological ecology by storing and releasing lipids according to metabolic and nutritional needs. However, excessive mesenteric fat can lead to metabolic disorders [9]. Mesenteric adipocytes can phagocytose bacteria translocated from the intestine and thus prevent systemic bacteria dissemination.…”