Enhancement of cutaneous immune response to bacterial infection after low-level light therapy with 1072 nm infrared light: a preliminary study.

ABSTRACT

We investigated the photobiomodulation effects of 1072 nm infrared light on the natural immune response involved in anti-bacterial and wound healing processes. Thirty mice infected with MRSA on the skin were divided into two groups. The experimental group was treated with 1072 nm infrared light (irradiance 20 mW/cm(2), fluence 12 J/cm(2) for 10 min) at 2, 4, 8, 12, 24 h, 3 and 5 days after inoculation and the control group with sham light. Serial changes of the mRNA levels of TLR2, IL-1ß, TNF-α, IL-6, iNOS, MCP-1, TGF-ß, bFGF and VEGF were studied by real time RT-PCR and those of the expression level of VEGF, bFGF, TGF-ß and NF-κB by immunohistochemistry. The mRNA levels of the cytokines involved in the early phase of anti-bacterial immune response (IL-1ß, TNF-α, IL-6, MCP-1) increased significantly in the 1072 nm group, peaking between 12 and 24 h post-inoculation. These levels normalized after 3-5 days. Immunohistochemistry revealed a notably stronger expression of VEGF in the 1072 nm group from 8-h post-inoculation to 5-day post-inoculation. We concluded that 1072 nm infrared light had a photobiomodulation effect which resulted in an enhanced biological immune response to the bacterial infection by MRSA and also increased the expression of VEGF to a significant level.