Regulation of cytokines and chemokines during the progression of acute inflammation in the human whole blood model.

摘要

Traumatic injuries or infectious challenges activate the innate immune response, initiating inflammation and cytokines and chemokines that are released into the circulation in distinct kinetic patterns. In the clinic, patients often present after the onset of inflammation, however few studies have investigated if the difference in cytokine and chemokine kinetics affects their ability to be regulated by anti-inflammatory reagents. To address this, the whole blood model was used to (1) characterize 24 hour acute inflammation; (2) determine if postponing the addition of the anti-inflammatory glucocorticoid dexamethasone (DEX) until after an inflammatory stimulus had any consequences on its ability to regulate cytokines and chemokines; and (3) determine if the effects of post-stimulus DEX were cell-type specific. The Toll-like Receptor 4 (TLR4) agonist lipopolysaccharide (LPS) or the TLR2 agonist Pam3-Cysteine-Serine-Lysine 4 (Pam) was used to activate the inflammatory response in whole blood. The levels of pro-inflammatory cytokines tumor necrosis factor, interleukin-1 beta, and IL-6 and IL-8 and Growth Related Oncogene alpha (GROalpha) chemokines were indicators of inflammation. LPS stimulation of whole blood induced rapid TNF, IL-beta and IL-6 protein and messenger Ribonucleic Acid (mRNA) over 24 hours. Pam stimulation caused slower induction of IL-10 and IL-6 protein. Both stimuli induced a continuous increase in IL-8 and GROalpha protein and mRNA levels. Concomitant addition of LPS or Pam and DEX to whole blood significantly suppressed cytokine and chemokine protein levels compared with either stimulus alone. Six hour DEX significantly suppressed IL-8 and GROalpha mRNA at 24 hours compared with LPS alone. Pam-induced cytokine and chemokine protein was also suppressed by 6 hour DEX. Additional experiments designed to determine if these effects were cell-type specific indicated that 24 hours after LPS stimulation, isolated neutrophils produced a substantial amount of IL-8 mRNA. Administration of DEX 6 hours after LPS stimulation suppressed IL-8 mRNA levels in neutrophils and monocytes. These data indicate that the administration of anti-inflammatory reagents to a patient presenting in the clinic as little as 6 hours after the onset of inflammation more likely improves inflammation by suppressing the message and thus protein of inflammatory mediators, such as chemokines, which persist beyond 6 hours.