Systemic neutrophil priming by lipid mediators in post-shock mesenteric lymph exists across species.
BACKGROUND
Post-hemorrhagic shock mesenteric lymph (PHSML) has been linked with neutrophil (PMN) priming, endothelial cell (EC) activation, and acute lung injury (ALI) in rodent models. We have previously identified the lipid fraction of PHSML as containing the causative agent(s). Due to the lesson learned from the rodent gut bacterial translocation experience, we sought to confirm this phenomenon using a large animal model; hypothesizing that lymph collected from the porcine gut following ischemia/reperfusion (I/R) would cause PMN priming.


METHODS
Mesenteric lymph was collected from adult pigs before, during, and for 2 hours after non-lethal hemorrhagic shock (mean arterial pressure = 30 mm Hg x 45 minutes). Whole lymph and the extracted lipid fractions of the lymph were then added to isolated human and porcine PMNs and superoxide production was measured by cytochrome C reduction.


RESULTS
Hemorrhagic shock profoundly affected mesenteric lymph flow from baseline (pre-shock) flow rates of 75.63 +/- 8.86 mL/hr to 49.38 +/- 5.76 mL/hr during shock and increasing to 253.38 +/- 27.62 mL/hr after 2 hours of resuscitation. Human PMNs exposed to both whole lymph (PHSML) and its extracted lipids (PHSML Lipid) collected 2 hours after shock exhibited more than a two-fold increase in superoxide release upon activation compared with pre-shock samples: PHSML- 6.27 +/- 0.83 versus 2.56 +/- 0.60 nmolO2(-)/ 3.75 cells/mL/min, respectively (p = 0.007), PHSML Lipid- 4.93 +/- 0.34 versus 2.49 +/- 0.11 nmolO2(-)/ 3.75 cells/mL/min (p < 0.001). Similarly, porcine PMNs exhibited close to a two-fold activation when exposed to the lymph and lipid fraction: PHSML- 4.51 +/- 0.42 versus 1.06 +/- 0.28 nmolO2(-)/ 3.75 cells/mL/min (p = 0.008), PHSML Lipid-4.80 +/- 0.81 versus 1.55 +/- 0.23 nmolO2(-)/ 3.75 cells/mL/min (p = 0.002).


CONCLUSIONS
Mesenteric lymphatics serve as the conduit for inflammatory mediators elaborated by the post-ischemic gut in both small and large animal models. Further, the causal agent(s) exist in the lipid fraction of the lymph and are active on both human and animal PMNs.
Sarin
Eric L
EL
Departments of Surgery, Denver Health Medical Center and University of Colorado Health Sciences Center, Denver, Colorado 80204, USA.
Moore
Ernest E
EE
Moore
John B
JB
Masuno
Tomohiko
T
Moore
Jessica L
JL
Banerjee
Anirban
A
Silliman
Christopher C
CC
D000818:Animals; D045304:Cytochromes c / Q000097:blood; D004195:Disease Models, Animal; D008055:Lipids / Q000097:blood*; D008208:Lymphatic System / Q000098:blood supply* / Q000293:injuries; D009504:Neutrophils / Q000502:physiology*; D051381:Rats; D015427:Reperfusion Injury / Q000097:blood / Q000503:physiopathology; D012771:Shock, Hemorrhagic / Q000097:blood* / Q000503:physiopathology; D012774:Shock, Traumatic / Q000097:blood* / Q000503:physiopathology; D013152:Splanchnic Circulation / Q000502:physiology*; D013481:Superoxides / Q000097:blood; D013552:Swine
D008055:Lipids; D013481:Superoxides; D045304:Cytochromes c