Table 3. Different immunological phases in local site of trauma and systemic circulation following sterile trauma.
|
Immunological events following sterile trauma |
||||
|---|---|---|---|---|
|
Activation phase |
Suppression phase |
|||
| Local | Systemic | Local | Systemic | |
| Macrophages | Inflammatory M1 polarization | — | Anti-inflammatory M2 polarization | Anti-inflammatory M2 polarization |
| Monocyte | Inflammatory phenotype | Monocytosis | Differentiation into anti-inflammatory phenotype | Increase in the number of anti-inflammatory phenotypes. |
| Neutrophil | Migration into the site of injury | Neutrophilia | Apoptosis of neutrophils at the site of injury | Overall increase in number of neutrophils however probably immature or less active |
| Lymphocyte | Inflammatory Th1 pathway | Increase in lymphocyte apoptosis | Anti-inflammatory Th2 pathway | Anti-inflammatory Th2 pathway |
| NK cells | — | — | Decrease in NK cell function | Decrease in NK cell function |
| DAMPs | Elevated levels of DAMPs trigger immediate release of cytokines to facilitate inflammation | — | Elevated levels of DAMPs direct anti-inflammatory activities to favor wound healing | DAMPs direct anti-inflammatory activities to favor systemic PTI |
| HPA axis | Immediate HPA axis-mediated signaling to initiate injury induced responses | — | Cortisol- and prostaglandin-mediated suppression to favor healing | Cortisol and prostaglandin also have role in systemic suppression |
| Acute phase proteins | Immediate release as part of body's inflammatory activities | Decreased levels of positive APPs | Trigger local immunosuppressive responses | Trigger immunosuppressive responses |
| MDSCs | — | Release of MDSCs from the source | Possible recruitment of MDSCs to the site of injury to facilitate local healing | Sustained release of MDSCs probably direct towards systemic suppression |
| Cytokines | Immediate release of different inflammatory and anti-inflammatory cytokines | Continued release of anti-inflammatory cytokines, whereas downregulation of pro-inflammatory cytokine release | Reductions in inflammatory cytokines such as IL-1β, IL-2, TNF-α, IFN-γ and IL-17A, whereas elevations in anti-inflammatory IL-5 | |
Abbreviations: AAP, acute phase protein; DAMP, damage-associated molecular pattern; IL, interleukin; HPA, hypothalamus–pituitary–adrenal; MDSC, myeloid-derived suppressor cell; NK, natural killer; TNF, tumor necrosis factor.