Multiple Cytokine Pathways Involved in Pulmonary Inflammation and Fibrosis

Pulmonary inflammation and fibrosis are driven by a complex interplay of multiple cytokine pathways. These pathways involve various cytokines, chemokines, growth factors, and their receptors that regulate immune cell recruitment, fibroblast activation, extracellular matrix deposition, and tissue remodeling within the lung. The dysregulation or persistent activation of these signaling networks leads to chronic inflammation and progressive fibrotic changes characteristic of diseases such as idiopathic pulmonary fibrosis (IPF) and systemic sclerosis-associated pulmonary fibrosis (SSc-PF). Key cytokines involved include TGF-β1, PDGF, IL-6, IL-11, TNF-α, IL-17, IL-4 and IL-13. Important chemokine axes are CXCL12–CXCR4, CCL2–CCR2, CCL3–CCR5, and CCL21–CCR7. Cellular sources of these cytokines are immune cells (Th17/Th2 lymphocytes, macrophages) and structural lung cells (alveolar epithelial/endothelial cells, fibroblasts/myofibroblasts). Targeted responses include modulation of gene expression via receptor-mediated signaling cascades such as NF-kB or JAK/STAT pathways leading to altered cellular behavior. Therapeutic implications include the potential for multi-target approaches modulating several key nodes within these networks.