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Thoracic Duct Lymph Suppresses the Release of Inflammatory Mediators from Macrophages in vitro
Author(s) -
Castillo Rudy,
Hodge Lisa
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.683.6
Subject(s) - lymph , thoracic duct , pathology , inflammation , lipopolysaccharide , immunology , tumor necrosis factor alpha , medicine
The thoracic duct distributes a large pool of lymph rich in immune cells, inflammatory mediators and lipids to blood circulation. Recent literature suggests that during gastrointestinal injury, soluble factors in mesenteric lymph redistribute to the lung, via the thoracic duct, where they initiate inflammation and contribute to multiple organ dysfunction syndrome (MODS). Alternatively, normal mesenteric lymph has been shown to suppress inflammation in vivo and in vitro . Specifically, under inflammatory conditions, normal mesenteric lymph reduced the expression of cell adhesion molecules on endothelial cells and inhibited neutrophil apoptosis in vitro . However, the role of normal lymph on macrophage function remains unknown. Importantly, macrophages have been to shown to contribute to MODS. The purpose of this study was to investigate the effect of normal lymph on macrophage function. Specifically, we hypothesized that normal thoracic duct lymph (TDL) would suppress the release of inflammatory mediators by LPS‐activated macrophages. To test this hypothesis, under anesthesia the thoracic ducts of four mongrel dogs were cannulated and lymph was collected. The TDL was centrifuged to remove cells and the TDL supernatant was frozen at −80°C. Murine RAW 264.7 macrophages were cultured in vitro with TDL at 5% total volume per well with or without of lipopolysaccharide (LPS). Twenty‐four hours after incubation at 37°C with 5% CO2, culture supernatants were assayed for nitric oxide (NO) and tumor necrosis factor‐alpha (TNF‐a) production. Macrophage viability was measured using flow cytometry with the markers Annexin V and Propidium Iodide. TDL did not augment the production of NO, TNF‐a or alter cell viability by macrophages cultured in media alone. However, when macrophages were activated with LPS, TDL suppressed the release of NO and TNF‐a. Specifically, LPS induced the release of NO (21±0.5 uM) and TNF‐a (7185±828 pg/mL). The addition of TDL suppressed the LPS‐induced release of NO (15±0.6 uM) and TNF‐a (5016±425 pg/mL). Culture with LPS and/or TDL did not alter cell viability. Our data suggests that during stimulation with LPS, a biological factor in lymph suppressed the release of inflammatory mediators by macrophages. Furthermore, cell viability was unaltered, suggesting that that TDL augments macrophage function. Future studies will focus on the ability of lymph to suppress the inflammatory response in disease models. Support or Funding Information This study was funded by the National Institutes of Health R01AT004361 (LMH).