| Biomarker | Principal activity | Lung fluid levels in BPD | Reference(s) |
| Chemokines | |||
| IL8 (CXCL8) | Chemotactic for neutrophils | Raised in infants who develop BPD, especially in week 1; associated with microbial colonisation of airways | 5, 12–18 |
| MCP-1 (CCL2) | Chemotactic for monocytes, lymphocytes | Higher concentrations in week 1 associated with BPD, especially with Ureaplasma urealyticum | 14, 16, 22 |
| MCP-2 (CCL8) | Chemotactic for mast cells, monocytes, NK cells | Higher concentrations in week 1 associated with BPD | 22 |
| MCP-3 (CCL7) | Chemotactic for monocytes, regulates macrophages | ||
| MIP-1α (CCL3) | Activates granulocytes; induces IL1, IL6, TNFα | ||
| MIP-1β (CCL4) | Activates granulocytes: induces IL1, IL6, TNFα | Maximum concentration associated with oxygen at 28 days | 22 |
| Adhesion molecules | |||
| ICAM-1 | Firm adhesion and migration of neutrophils | Increased concentrations at 10 days in infants with BPD | 21 |
| L-selectin | “Rolling” of neutrophils | Increased concentrations on day 7, but not day 0 in infants with BPD | 25 |
| Pro-inflammatory cytokines | |||
| IL1 | Activates lymphocytes, increases expression of adhesion molecules | Increased concentrations associated with duration of supplemental oxygen and duration of mechanical ventilation | 19, 27–29 |
| TNFα | Enhances leucocyte endothelial activation, activates macrophages | ||
| IL6 | Increases inflammatory cytokine production | ||
| IL8 | Neutrophil activation and degranulation | ||
| Proteases/inhibitors of proteases | |||
| MMPs | Breakdown extracellular matrix proteins | Increased concentrations, especially in relationship to low TIMP activity, associated with BPD | 34, 35 |
| TIMP | Inhibits MMP activity | ||
| Trypsin | Matrix degradation, activates MMP | Increased concentrations associated with BPD | 39 |
| Anti-inflammatory cytokines | |||
| IL10 | Inhibitor of macrophages | Levels rise earlier but drop faster in infants with BPD; lower levels in infants with BPD | 50, 51 |
| CC10 (Clara cell) | Inhibits phospholipase A2 (degrades phospholipid component of surfactant) | Lower levels of CC10 associated with increased risk of BPD | 53 |
| Growth factors | |||
| BLP | Stimulatory effect in fetal lung development | Increased concentrations in urine associated with increased risk of BPD | 45, 46 |
| TGFβ | Stimulates fibroblasts and fibrosis | Predictive marker of severe BPD | 56 |
| VEGF | Stimulates angiogenesis | Decreased in infants with BPD | 64 |
BLP, bombesine-like peptide; BPD, bronchopulmonary dysplasia; ICAM, intercellular adhesion molecule; IL, interleukin; MCP, monocyte chemoattractant protein; MIP, monocyte inflammatory protein; MMP, matrix metalloprotease; TGF, transforming growth factor; TIMP, tissue inhibitor metalloprotease; TNF, tumour necrosis factor; VEGF, vascular endothelial growth factor.