Aim: Evaluating the role of interleukin-6 (IL-6) as an early predictor of sepsis in a murine model.
Materials and methods: The study divided 26 Wistar rats into two experimental groups in which sepsis was induced through the intraperitoneal injection of different Escherichia coli cultures [Group 1: Extended-spectrum beta-lactamase (ESBL)-producing culture and Group 2: Standardized ATCC35218 culture] and a control group. IL-6 levels were determined at 5 and 24 hours post-inoculation and immunohistochemistry (IHC) was performed on tissue samples from the sacrificed animals.
Results: Mean plasma IL-6 levels in Group 1 peaked at 5 hours [37.4 pg∕mL; standard deviation (SD) = 2.4 pg∕mL] and decreased at 24 hours (34 pg∕mL; SD=3.2 pg∕mL) after inoculation. IL-6 levels in Group 1 were elevated compared to Group 2, at 5 hours (33.7 pg∕mL; SD=3.3 pg∕mL; p=0.019) and non-significantly so at 24 hours (32.5 pg∕mL; SD=2.4 pg∕mL; p=0.233). The results did not show an increase over control levels at either 5 hours (37.6 pg∕mL; SD=3.4 pg∕mL) or 24 hours (40.8 pg∕mL; SD=2.9 pg∕mL) after inoculation. The IHC shows a varying degree of IL-6 expression across all organ types studied. No statistically significant correlations were found between the tissue level quantification of IL-6 and serum values at 24 hours in either group.
Conclusions: For an early stage of infection/inflammation, serum levels of IL-6 are not correlated with tissue-level inflammation disproving a potential role of IL-6 as a very precocious diagnostic and predictor test. Accumulation of IL-6 in lung, kidney and spleen tissue can be observed from the beginning of inflammation.