PF4 and systemic sclerosis: Patients with severe dSSc exhibited a significant reduction in the number of scleroderma-specific fibroblasts, which correlated with SSc severity.8 Cellular activation in SSc is associated with excessive production of pro-inflammatory and pro-fibrotic cytokines, chemokines, and growth factors, including interleukin (IL)-1β, IL-6, IL-4, IL-10, tumor necrosis factor-α, tissue growth factor-β, CCL18, CXCL4, toll like receptor-4, interferons type 1 and 2, and others.9