Analysis of Inflammatory Response, Immune Checkpoints and Macrophage Recruitment in the Repair Process of Abdominal Stretch Marks

• Grant number: 22/12292-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2022
• End date: November 30, 2023
• Field of knowledge: Biological Sciences - Morphology - Anatomy
• Principal Investigator: Wagner José Fávaro
• Grantee: Milena Olivieri Roston
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Stretch marks are common skin lesions, resulting from stretching or distension of the skin, due to the rupture of elastic and collagen fibers. Its treatment is quite challenging, whether in the prophylactic or preventive form and so far, no therapy is sufficiently effective and with minimal adverse effects. In this sense, it is necessary to develop new therapeutic approaches for the treatment of stretch marks. Platelet Rich Plasma (PRP) is a concentration of platelets in a small volume of plasma, with the presence of growth factors (GFs), which are released when activated. Furthermore, platelets contribute to immune regulation, participating in adaptive and innate immune functions, mediated by Toll-like receptors (TLRs). Activation of TLRs is a key element in initiating and mediating inflammation after tissue injury. Targeting TLRs or their signaling pathways may provide new therapeutic strategies for tissue repair, including the treatment of abdominal striae. Our preliminary studies aimed at evaluating the effects of PRP treatment on abdominal striae of Caucasian patients, allowed us to characterize and compare the structural alterations of collagen and elastic fibers in the abdominal striae of patients undergoing treatment with PRP; in addition to establishing possible mechanisms of action of this treatment involving the signaling pathway of the immune system receptors (TLRs) and GFs. The results obtained showed that the treatment with PRP, especially the application by quadrant, was effective in reducing the area of the abdominal striae, with consequent stimulation of the synthesis and remodeling of collagen and elastic fibers. Immunohistochemical analyzes showed that treatment with PRP per quadrant promoted an increase in immunoreactivities for TLR2 and TLR4, with a consequent increase in TNF-±. Thus, it can be concluded that the use of PRP in patients with stretch marks constituted a promising therapeutic approach, since it promoted modulation of inflammatory cytokines and growth factors, with consequent remodeling of the fibrillar elements of the extracellular matrix, culminating in tissue improvement. In view of the above, a retrospective study is proposed, with the objective of evaluating the inflammatory response of immunological checkpoints and recruitment of inflammatory cells, especially macrophages with M1 profile, in the repair process of abdominal striae in Caucasian patients treated with PRP.