Cellular Microenvironment Stiffness Regulates Eicosanoid Production and Signaling Pathways.

Area of Science:

• Biochemistry
• Cell Biology
• Pulmonary Medicine

Background:

• Pathological matrix stiffening in idiopathic pulmonary fibrosis (IPF) promotes fibroblast activity and impairs prostaglandin E2 (PGE2) synthesis.
• Reduced expression of cyclooxygenase-2 (COX-2) and prostaglandin E synthase (PTGES) is observed in IPF lungs.

Purpose of the Study:

• To investigate the role of PTGES in IPF.
• To examine the impact of microenvironment stiffness on prostanoid biosynthesis in IPF and non-IPF fibroblasts.
• To explore the involvement of p38 mitogen-activated protein kinase (MAPK) signaling.

Main Methods:

• Analysis of PTGES expression in IPF patient lungs.
• Culture of human lung fibroblasts in soft hydrogels and spheroids versus stiff plastic.
• Assessment of COX-2, PTGES, prostaglandin E receptor 4 (EP4), and cytosolic phospholipase A2 (cPLA2) expression.
• Inhibition studies using SB203580 (p38 MAPK inhibitor).
• Measurement of PGE2 levels.

Main Results:

• Lower PTGES expression in IPF lungs.
• Substantial induction of COX-2, PTGES, EP4, and cPLA2 in soft microenvironments (hydrogels, spheroids).
• p38 MAPK inhibition partially reduced COX-2, cPLA2, and PTGES induction in spheroids.
• Increased PGE2 levels observed only in non-IPF fibroblast spheroids.

Conclusions:

• IPF fibroblasts exhibit dysregulated prostanoid biosynthesis and signaling pathways.
• Soft microenvironments partially restore these pathways but do not fully abrogate dysregulation in IPF.
• Biomechanical cues significantly influence prostanoid synthesis and signaling in lung fibroblasts.