1. Figure 4 Intestinal lacteal absorption and immune cell trafficking
Figure 4 | Intestinal lacteal absorption and immune cell trafficking. a | Intestinal lymphatics are the main route of absorption for fat, cholesterol, fat-soluble vitamins, food antigens, bacteria-derived lipopolysaccharides (LPS) and incretin hormones, such as glucagon-like peptide 1 (GLP1). In enterocytes, long-chain fatty acids, cholesterol and the fat-soluble vitamins A, D, E and K, and LPS are packaged into chylomicrons, which are then secreted basolaterally into the lamina propria. These chylomicrons, which are prevented from entering the fenestrated villus blood capillaries by size exclusion, enter the lacteal through flap valves formed by button junctions. Although glucose and peptide YY (PYY) are absorbed equally by villus blood capillaries and lacteals in mice, GLP1 is selectively transported by lymphatic vessels, probably owing to low expression of the GLP1 protease dipeptidyl peptidase 4, by lymphatic endothelial cells103. b | Intestinal lymphatic transport of dendritic cells and innate lymphoid cells (ILCs). Intestinal lumen antigens or circulating antigens are bound by CX3CR1+ macrophages, and transferred to CD103+ dendritic cells. Alternatively, dendritic cells can acquire antigens directly through the lumen or from goblet cells. CCR7+ dendritic cells and ILC3s migrate through lymphatic capillary flap valves to the mesenteric lymph node in response to a CCL21 gradient produced by lymphatic endothelial cells. MLN, mesenteric lymph node.
Bernier-Latmani, J. & Petrova, T. V. (2017) Intestinal lymphatic vasculature: structure, mechanisms and functions
Nat. Rev. Gastroenterol. Hepatol. doi: /nrgastro