Figure 4.

Schematic representation of the inflammatory profile at the initiation of the age-related lobular involution (A) and once it is completed (B) and SFRP1 expression modulation during a woman’s life considering the parity status (C). (A) SFRP1 induces the initiation of the age-related involution. Its expression is correlated with inflammatory molecules produced by epithelial cells (leptin, TNF-α, IL-6, and CRP) involved in the immune system activation and the involution-related adipogenesis. Microcalcifications’ development, which is exacerbated by advanced age at first delivery, is positively correlated with the expression of SFRP1 expression but negatively with CRP expression in nulliparous women specifically. (B) After lobular involution, SFRP1 is less expressed. Inflammatory molecules that were once produced by epithelial cells are now produced by adipocytes when lobular involution is completed. The absence of SFRP1 expression is also responsible for the decrease in adipogenesis, the downregulation of monocytes and pre-adipocytes’ differentiation into mature adipocytes and the decrease of the immune system activation. Lactoferrin is downregulated in nulliparous women. (C) The peak of SFRP1 expression occurs during age-related lobular involution in nulliparous women, resulting in a fast process followed by a dramatic fall in SFRP1 expression. On the other hand, the peak of SFRP1 expression occurs during the late phase of lactation in parous women, resulting in a progressive lobular involution followed by a slight decrease in the expression of SFRP1 expression.