N. J. Galbraith1, S. Walker1, M. Cahill1, S. Gardner1, H. C. Polk1 1Price Institue Of Surgical Research,Department Of Surgery,Louisville, KY, USA
Introduction:
Major trauma often leads to impaired host defenses. Specifically, subnormal monocyte function (seen in approximately a sixth of all such patients) has repeatedly been shown to be associated with infection-related complications. However, identifying the ‘at risk’ patient, as well as understanding the pathophysiology behind this disturbance, continues to elude the investigators. MicroRNAs hold the potential as stable biomarkers that fine tune host defenses. We aim to identify novel microRNA (miRNA) associated with the impaired monocyte response.
Methods:
We produced ‘impaired’ human monocytes by exposure to LPS 10ng/mL (each containing 2.5 x 105 monocytes) and compared them to similarly incubated naïve monocytes. Both preparations were then challenged with LPS 100ng/mL and the production of TNFα, IL-6 and IL-10 (ELISA) and HLA-DR expression (flow cytometry) were determined. MiRNA profiling was undertaken using microfluidic array technology (n = 4 for each determination).
Results:
Monocytes exposed to LPS 10ng/mL were found to have lower TNFα, IL-6 and IL-10 production in response to an LPS 100ng/mL challenge, when compared to the naïve monocyte (p < 0.05, paired T-test). Furthermore, these impaired cells had lower HLA-DR expression (p<0.05). MiRNA profiling revealed that when compared to the naïve monocyte, the LPS-impaired cells had upregulated miRNA- 487a & miRNA-655, yet downregulated miRNA-433 & miRNA-450a (p = <0.05).
Conclusion:
The precise processes behind immune dysfunction that appear following major trauma remain unclear. We have identified four dysregulated miRNAs associated with the impaired monocyte inflammatory response. Further study of these, and approximately 20 more differentially expressed miRNAs based on our preliminary data and literature consultation, may identify other markers, some of which may be associated with important signaling mechanisms present in the high risk patient.