Cross-Transfusion of Postshock Mesenteric Lymph Provokes Acute Lung Injury

Abstract

Objective Substantial investigation has implicated mesenteric lymph as the mechanistic link between gut ischemia/reperfusion (I/R) and distant organ injury. Specifically, lymph diversion prevents acute lung injury (ALI) in vitro and bioactive lipids and proteins isolated from postshock mesenteric lymph (PSML), maintain bioactivity in vitro. However, Koch’s postulates remain to be satisfied via direct cross-transfusion into a naïve animal. We therefore hypothesized that real time cross-transfusion of postshock mesenteric lymph provokes acute lung injury. Methods One set of Sprague-Dawley rats (lymph donors) was anesthetized, with the mesenteric lymph ducts cannulated and exteriorized to drain freely into a siliconized plastic cup; concurrently, a second group of rats (lymph recipients) was anesthetized, with a cannula inserted into the animal’s right internal jugular vein. Blood was removed from the donor rats to induce hemorrhagic shock (MAP of 35 mmHg × 45 minutes). The recipient rats were positioned 10 cm below the plastic cup which emptied into the jugular vein cannula. Thus, mesenteric lymph from the shocked donor rat was delivered to the recipient rat at the rate generated during shock and the subsequent 3 hours of resuscitation. Results Neutrophil (PMN) accumulation in the lungs was substantially elevated in the postshock lymph cross-transfusion group compared to both sham lymph cross-transfusion and instrumented control (MPO: 9.42±1.55 vs. 2.81±0.82 U/mg lung tissue in postshock vs. sham lymph cross-transfusion, n=6 in each group, p=0.02). Additionally, cross-transfusion of PSML induced oxidative stress in the lung (0.21±0.03 vs. 0.10±0.01 micromoles MDA per mg lung tissue in lymph cross-transfusion vs. instrumented control, n=6 in each group, p = 0.046). Furthermore, transfusion of PSML provoked lung injury (BAL protein 0.77±0.18 vs. 0.15±0.02 mg/ml protein in BALF, postshock vs. sham lymph cross-transfusion, n=6 in each group, p=0.004). Conclusion Cross-transfusion of PSML into a naïve animal leads to PMN accumulation and provokes ALI. These data provide evidence that postshock agents released into mesenteric lymph are capable of provoking distant organ injury.

A “Clean Case” of Systemic Injury

“…We have demonstrated previously that within three hours of hemorrhagic shock, a significant inflammatory response with systemic effects occurs (11, 13, 28). This study confirms that both trauma and hemorrhagic shock can increase the presence of mitochondrial DAMPs as demonstrated by increased mitochondrial DNA in mesenteric lymph.…”

“…In 1998, Magnotti et al had confirmed that mesenteric lymph carried gut-derived mediators of endothelial permeability and lung injury following hemorrhagic shock (12). Post-shock mesenteric lymph (PSML) was subsequently shown to be a bioactive body fluid capable of inciting remote organ dysfunction in the lung (11), kidney (13), and heart (14, 15). Further, mesenteric lymph serves to prime quiescent neutrophils for enhanced respiratory burst (16) potentially via mechanisms related to the release of inflammatory lipid mediators such as phospholipase A2 and 5-lipoxygenase products (13, 17).…”

“…PSML has also been demonstrated to enhance leukocyte sequestration as elaborated by up-regulation of both neutrophil and endothelial cell adhesion molecules (18-20). Moreover, cross-transfusion of PSML into naïve rats elicited acute lung injury without the presence of T/HS (11), while mesenteric duct ligation prior to T/HS mitigated this injury (14, 18, 21). …”

“…T/HS was simulated per our established model (11). Briefly, Sprague-Dawley rats weighing 350g to 400g (Harlan Labs, Indianapolis, IN) were housed in a climate controlled barrier facility with 12-hour light/dark cycles with free access to food and water for a period of at least 1 week prior to experimental procedures.…”

The imbalance between regulatory and IL-17-secreting CD4+T cells in multiple-trauma rat

“…The proximal portion of the small intestine was quickly removed and flushed with 0.01 mol l -1 cold phosphate buffer solution (PBS, pH 7.4) and immersed for 24 h in 10% buffered formalin for assessment of intestinal histological change. [23][24][25] Flow cytometric analysis of Th17 and Treg…”