title: Intravital imaging of intestinal lacteals unveils lipid drainage through contractility.
abstract: Lacteals are lymphatic vessels located at the center of each intestinal villus and provide essential transport routes for lipids and other lipophilic molecules. However, it is unclear how absorbed molecules are transported through the lacteal. Here, we used reporter mice that express GFP under the control of the lymphatic-specific promoter Prox1 and a custom-built confocal microscope and performed intravital real-time visualization of the absorption and transport dynamics of fluorescence-tagged fatty acids (FAs) and various exogenous molecules in the intestinal villi in vivo. These analyses clearly revealed transepithelial absorption of these molecules via enterocytes, diffusive distribution over the lamina propria, and subsequent transport through lacteals. Moreover, we observed active contraction of lacteals, which seemed to be directly involved in dietary lipid drainage. Our analysis revealed that the smooth muscles that surround each lacteal are responsible for contractile dynamics and that lacteal contraction is ultimately controlled by the autonomic nervous system. These results indicate that the lacteal is a unique organ-specific lymphatic system and does not merely serve as a passive conduit but as an active pump that transports lipids. Collectively, using this efficient imaging method, we uncovered drainage of absorbed molecules in small intestinal villus lacteals and the involvement of lacteal contractibility.
authors.forename: Kibaek
authors.initials: K
authors.lastname: Choe
authors.forename: Jeon Yeob
authors.initials: JY
authors.lastname: Jang
authors.forename: Intae
authors.initials: I
authors.lastname: Park
authors.forename: Yeseul
authors.initials: Y
authors.lastname: Kim
authors.forename: Soyeon
authors.initials: S
authors.lastname: Ahn
authors.forename: Dae-Young
authors.initials: DY
authors.lastname: Park
authors.forename: Young-Kwon
authors.initials: YK
authors.lastname: Hong
authors.forename: Kari
authors.initials: K
authors.lastname: Alitalo
authors.forename: Gou Young
authors.initials: GY
authors.lastname: Koh
authors.forename: Pilhan
authors.initials: P
authors.lastname: Kim
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology; D001692:Biological Transport; D004396:Coloring Agents / Q000493:pharmacokinetics; D004041:Dietary Fats / Q000493:pharmacokinetics*; D020895:Enterocytes / Q000378:metabolism*; D005227:Fatty Acids / Q000493:pharmacokinetics*; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis; D018398:Homeodomain Proteins / Q000235:genetics; D007408:Intestinal Absorption / Q000502:physiology*; D007413:Intestinal Mucosa / Q000648:ultrastructure*; D007421:Intestine, Small / Q000378:metabolism*; D000069416:Intravital Microscopy; D042601:Lymphatic Vessels / Q000187:drug effects / Q000294:innervation / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D018715:Microscopy, Video; D008871:Microvilli / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000235:genetics; D000098551:Prospero-Related Homeobox 1 Protein
chemical_list: D004396:Coloring Agents; D004041:Dietary Fats; D005227:Fatty Acids; D005456:Fluorescent Dyes; D018398:Homeodomain Proteins; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; D049452:Green Fluorescent Proteins; D009638:Norepinephrine