Review on the molecular mechanisms of low-level laser therapy: gene expression and signaling pathways

Low-level laser therapy (LLLT) has been shown to influence cellular and molecular processes in irradiated tissues and cells. By altering gene expression and activating specific laser-induced signaling pathways, LLLT can impact key cellular activities such as proliferation, differentiation, migration, and metabolism. This review focuses on exploring the molecular-level effects of LLLT, examining how different wavelengths interact with various cell lines, including stem cells, to induce these changes in gene expression and signaling pathways. A comprehensive review was performed by analyzing relevant literature published between 2003 and 2024. The search utilized databases such as PubMed, Scopus, MEDLINE, EMBASE, and Google Scholar. Selection criteria were based on the presence of keywords including "gene expression," "signaling pathways," "molecular mechanisms," "photobiomodulation," and "LLLT." Among the 150 recent studies on low-level laser therapy and its molecular and cellular effects on irradiated cells, articles related to changes in gene expression and laser-induced signaling pathways were reviewed. Low-level laser therapy exhibits varying effects based on the parameters and wavelengths used. Red and infrared lasers are particularly effective for promoting cell proliferation, differentiation, reducing inflammation, and enhancing wound healing. Blue lasers tend to inhibit cell proliferation, while green lasers are effective in reducing inflammation and aiding in conditions such as intervertebral disc (IVD) degeneration. These effects are linked to changes in gene expression and laser-induced signaling pathways, highlighting the importance of selecting the appropriate laser type for specific therapeutic goals.