Role of Substance P-Dependent Chemotactic Signaling in Postoperative Adhesion Formation

Area of Science:

• Surgical complications
• Inflammation and immunology
• Molecular and cellular biology

Background:

• Postoperative adhesions are a serious complication of abdominal surgery.
• Substance P (SP) acting via the neurokinin-1 receptor (NK-1R) is an early mediator of adhesion formation, regulating the fibrinolytic system.
• SP also drives neurogenic inflammation by recruiting leukocytes like neutrophils and macrophages.

Purpose of the Study:

• To investigate the role of SP-dependent leukocyte recruitment via CXCR2 in postsurgical adhesion formation.
• To determine if CXCR2 signaling contributes to adhesion formation through the fibrinolytic system.

Main Methods:

• A mouse cecal cauterization model was employed to induce intra-abdominal adhesions.
• Expression of chemokines (CXCL1, CXCL2) and CXCR2 was quantified post-surgery.
• The effects of NK-1R and CXCR2 antagonists, and IFN-γ knockout were assessed.

Main Results:

• Both NK-1R and CXCR2 antagonists significantly inhibited postsurgical adhesion formation.
• Neutrophil chemokine and CXCR2 expression peaked at 3-6 hours post-surgery, partially dependent on SP and IFN-γ.
• NK-1R antagonism affected PAI-1 expression, but CXCR2 antagonism did not, indicating distinct mechanisms.

Conclusions:

• Postsurgical adhesiogenesis involves SP- and IFN-γ-dependent chemokine signaling.
• While SP impacts fibrinolysis, CXCR2-mediated signaling contributes to adhesion formation through pathways independent of PAI-1-mediated fibrinolysis inhibition.