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 siliconates 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 min). 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 h 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 versus 2.81 ± 0.82 U/mg lung tissue in postshock versus 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 versus 0.10 ± 0.01 micromoles MDA per mg lung tissue in lymph cross-transfusion versus instrumented control, n = 6 in each group, P = 0.046). Furthermore, transfusion of PSML provoked lung injury (BAL protein 0.77 ± 0.18 versus 0.15 ± 0.02 mg/mL protein in BALF, postshock versus 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.

Figure 1

The method of real-time cross-transfusion of mesenteric lymph from a donor rat undergoing trauma and hemorrhagic shock to a naïve recipient is illustrated.

Figure 2

PMN accumulation in the lungs was substantially elevated in the postshock lymph cross-transfused group (9.42±1.55 vs. 2.81±0.82 U/mg lung tissue in postshock vs. sham lymph cross-transfusion, indicated by an asterisk, p=0.02). The sham lymph cross-transfusion group levels were comparable to the instrumented controls (2.81±0.82 vs. 2.47±0.02 U/mg lung tissue, indicated by a number sign, p=0.35).

Figure 3

Oxidative lung injury was increased in the lymph transfused animals (MDA 0.21 ± 0.03 vs. 0.10 ± 0.01 micromoles MDA per mg lung tissue in lymph cross-transfusion vs. instrumented control, p = 0.046)

Figure 4

Transfusion of mesenteric lymph provoked acute lung injury (BAL protein 0.77±0.18 vs. 0.15±0.02 vs. 0.14±0.06 mg/ml protein in BALF, postshock lymph vs. sham lymph cross-transfusion, indicated by an asterisk, p=0.004). The sham lymph cross-transfusion group levels were comparable to the instrumented controls (0.15±0.02 vs. 0.14±0.06 mg/ml, indicated by a number sign, p=0.38).