314 - Blood screening for elevated inflammatory biomarkers as early identifiers of later mortality in a rat model of neonatal endotoxemia.

Publication Number: 314.3961

Catherine Mayer, UH Rainbow Babies & Children's Hospital, Cleveland, OH, United States; Peter M. MacFarlane, Case Western Reserve University School of Medicine, Cleveland, OH, United States

Background: Rats exhibit a lethal sensitivity to lipopolysaccharide (LPS) during the second week of postnatal life, suggesting a highly developmentally regulated immune system and a unique vulnerability to endotoxin. Specifically, we showed previously that LPS administration to postnatal (P) 10 day old rats results in ~50% mortality within 8 h of exposure. The mortality is unique to the P10 day old age group since younger (P5) and older (P20) age groups are relatively unaffected by LPS (Rourke et al., 2016). The cause of the unique developmental lethality of LPS expressed by some rat pups, but not others (i.e. litter mates) is unknown. Here, we investigated whether a blood screen for elevated systemic inflammatory biomarkers can be used for early identification of rats who exhibit a uniquely lethal vulnerability to LPS.

Objective: We hypothesize that elevated serum cytokine/chemokines in P10 day old rats identify individuals that exhibit a lethal vulnerability to endotoxemia.

Design/Methods: P10 day old male and female sprague Dawley rat pups were injected IP with 0.1mg/kg of LPS or saline as control. Two hours post-LPS or saline injection, serum was collected and then screened for multiple cytokine/chemokines using multiplex arrays. Eight hours post-LPS injection, mortality rates were determined and correlated with 2 hour serum cytokine/chemokines levels.

Results: LPS injected rats had a 43% mortality rate at 8 h compared to 0% in saline injected rat pups. In the LPS non-survivor group (LPS-NS), serum levels of IL-1 beta (1,841 +/- 448 ng/ml), IL-6 (321 +/- 57 ng/ml), TNF alpha (1,055 +/- 189 ng/ml) and mip-2 (23,087 +/- 3,473 ng/ml) were uniquely elevated (p < 0.05) at 2 h post-LPS, when compared to survivors of LPS (LPS-S) (IL-1 beta: 873 +/- 326 ng/ml; IL-6: 115 +/- 34 ng/ml; TNF alpha: 282 +/- 69 ng/ml; MIP-2: 1,1381 +/- 3555 ng/ml) and also compared to saline controls (C)(IL-1 beta: 12 +/- 0.5 ng/ml; IL-6: 0.09 +/- 0.09 ng/ml; TNF alpha: 3.31 +/- 0.5 ng/ml; MIP-2: 0.00 +/- 0.00 ng/ml). Other cytokines (including INF gamma, IL-10, IL17-A) were not different between groups.

Conclusion(s): In conclusion, elevations in distinct serum cytokines/chemokines may be useful biomarkers for early identification of neonates exhibiting a lethal vulnerability to endotoxemia. These data may provide insight into the unique vulnerabilities of neonatal infants to endotoxic shock during critical windows of postnatal development and reveal potential biomarkers for screening for earlier intervention for prevention of mortality from endotoxic shock.