Colonic Insult Impairs Lymph Flow, Increases Cellular Content of the Lymph, Alters Local Lymphatic Microenvironment, and Leads to Sustained Inflammation in the Rat Ileum.
BACKGROUND
Lymphatic dysfunction has been linked to inflammation since the 1930s. Lymphatic function in the gut and mesentery is grossly underexplored in models of inflammatory bowel disease despite the use of lymphatic occlusion in early models of inflammatory bowel disease. Activation of the innate and adaptive immune system is a hallmark of TNBS-induced inflammation and is linked to disruption of the intrinsic lymph pump. Recent identification of crosstalk between lymphatic vessel resident immune cells and regulation of lymphatic vessel contractility underscore the importance of the timing of lymphatic dysfunction during tissue inflammation in response to TNBS.


METHODS
To evaluate lymphatic function in TNBS induced inflammation, lymph was collected and flow measured from mesenteric lymphatics. Cellularity and cytokine profile of the lymph was also measured. Histopathology was performed to determine severity of injury and immunofluorescent staining of the mesentery was done to evaluate changes in the population of immune cells that reside near and on gastro-intestinal collecting lymphatics.


RESULTS
Lymph transport fell 24 hours after TNBS administration and began recovering at 72 hours. Significant reduction of lymph flow preceded significant increase in histopathological score and occurred simultaneously with increased myeloperoxidase activity. These changes were preceded by increased MHCII cells surrounding mesenteric lymphatics leading to an altered lymphatic environment that would favor dysfunction.


CONCLUSIONS
Alterations in environmental factors that effect lymphatic function occur before the development of gross GI inflammation. Reduced lymphatic function in TNBS-mediated inflammation is likely an early factor in the development of injury and that recovery of function is associated with resolution of inflammation.
*Division of Lymphatic Biology, Department of Medical Physiology, Texas A&M University Health Science Center College of Medicine, Temple, Texas; †Department of Physiology and Pharmacology, Inflammation Research Network, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada; and ‡Department of Surgery, Center for Cell Death and Differentiation, Texas A&M University Health Science Center College of Medicine, Temple, Texas.
Walter
W
Cromer
Wei
W
Wang
Scott D
SD
Zawieja
Pierre-Yves
PY
von der Weid
M Karen
MK
Newell-Rogers
David C
DC
Zawieja
D000818:Animals; D003106:Colon / Q000098:blood supply*; D003713:Dendritic Cells / Q000276:immunology* / Q000473:pathology; D004195:Disease Models, Animal; D007079:Ileitis / Q000209:etiology* / Q000276:immunology / Q000473:pathology; D007082:Ileum / Q000098:blood supply / Q000276:immunology / Q000473:pathology*; D007111:Immunity, Cellular; D007150:Immunohistochemistry; D007511:Ischemia / Q000150:complications* / Q000276:immunology / Q000473:pathology; D042601:Lymphatic Vessels / Q000473:pathology*; D051381:Rats