The Role of Selective Photodynamic Inactivation in Infections Influencing Skin Cancer Progression

• Grant number: 25/07428-3
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: January 01, 2026
• End date: November 30, 2027
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Vanderlei Salvador Bagnato
• Grantee: Rebeca Vieira de Lima
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 13/07276-1 - CEPOF - Optics and Photonic Research Center, AP.CEPID

Abstract

The skin microbiota plays a fundamental role in skin homeostasis, acting as both an immunological and metabolic barrier against pathogens. However, environmental factors such as ultraviolet (UV) radiation can cause dysbiosis. This condition favors the proliferation of pathogens such as Staphylococcus aureus, whose exacerbated colonization is associated with chronic inflammation and skin cancer. In contrast, Staphylococcus epidermidis exhibits antitumor properties and can inhibit both the colonization and biofilm formation of pathogenic S. aureus. Conventional treatments, such as antibiotics, may compromise the healthy microbiota and induce bacterial resistance. In this context, Photodynamic Inactivation (PDI) emerges as a selective and promising approach that employs photosensitizers activated by visible light to eliminate pathogens without disrupting eubiosis. This study investigates in vitro its impact on modulating the skin microbiota and inhibiting skin cancer progression, using mixed cultures of S. aureus and S. epidermidis to infect healthy and cancerous epithelial cells, thereby simulating different microbiological conditions. The effectiveness of PDI will be analyzed in terms of pathogen elimination, cancer cell anti-proliferation, and mitigation of microbiota disruption. The expected outcomes may contribute to the development of new treatments focused on preserving the microbiota in skin infections and preventing associated skin cancer. (AU)