• Andreas A Kroon, Jinxia Wang, Zhen Huang, Lei Cao, Maciej Kuliszewski, and Martin Post.
• Lung Biology Research, Physiology and Experimental Medicine Program, Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1X8, Canada.
• Pediatr. Res. 2010 Jul 1; 68 (1): 63-9.

AbstractHerein, we determined the contribution of mechanical ventilation, hyperoxia and inflammation, individually or combined, to the cytokine/chemokine response of the neonatal lung. Eight-day-old rats were ventilated for 8 h with low ( approximately 3.5 mL/kg), moderate ( approximately 12.5 mL/kg), or high ( approximately 25 mL/kg) tidal volumes (VT) and the cytokine/chemokine response was measured. Next, we tested whether low-VT ventilation with 50% oxygen or a preexisting inflammation induced by lipopolysaccharide (LPS) would modify this response. High-, moderate-, and low-VT ventilation significantly elevated CXCL-2 and IL-6 mRNA levels. Low-VT ventilation with 50% oxygen significantly increased IL-6 and CXCL-2 expression versus low-VT ventilation alone. LPS pretreatment combined with low-VT ventilation with 50% oxygen amplified IL-6 mRNA expression when compared with low VT alone or low VT + 50% O2 treatment. In contrast, low VT up-regulated CXCL-2 levels were reduced to nonventilated levels when LPS-treated newborn rats were ventilated with 50% oxygen. Thus, low-VT ventilation triggers the expression of acute phase cytokines and CXC chemokines in newborn rat lung, which is amplified by oxygen but not by a preexisting inflammation. Depending on the individual cytokine or chemokine, the combination of both oxygen and inflammation intensifies or abrogates the low VT-induced inflammatory response.

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