# Near-Infrared Laser Photobiomodulation Reduces Pro-Inflammatory Cytokines in an In Vitro Model of Bronchopulmonary Dysplasia: A Preliminary Report

## TL;DR

Near-infrared laser therapy reduced inflammation in a lab model of a lung disease in premature rabbits.

## Contribution

Demonstrates that photobiomodulation reduces pro-inflammatory cytokines in an in vitro model of BPD.

## Key findings

- PBMT protocols A and B reduced IL-6 and TNFα mRNA in lung slices.
- Protocol A was more effective than protocol B in reducing inflammation.
- Anti-inflammatory effects were more pronounced at 2 hours than at 6 hours post-treatment.

## Abstract

Background: The multifactorial pathogenesis of bronchopulmonary dysplasia (BPD) includes prematurity, inflammation, and oxidative stress. Photobiomodulation therapy (PBMT) using near-infrared (NIR) laser sources was found to have anti-inflammatory effects in several respiratory disorders. Our aim was to evaluate whether PBMT could reduce inflammation in an in vitro model of BPD. Materials and Methods: Precision-cut lung slices (PCLSs) from premature rabbits were exposed to lipopolysaccharide (LPS) and treated with three PBMT protocols (A, B, and C) differing for the treatment parameter such as fluence (energy delivered per unit area, laser A: 7.09, laser B: 7.41, laser C: 7.01 J/cm2) and exposure time (25, 20, 12 s, respectively). The expression level of TNFα and IL-6 was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR) after 2 or 6 h from PBMT. Results: PBMT protocols A and B reduced IL-6 and TNFα mRNA at both timepoints, although the effect was less pronounced after 6 h than after 2 h. Furthermore, protocol A, which involved intermediate fluence and longer laser exposure, was more effective than protocol B. Conclusions: PBMT with NIR laser sources has an effective anti-inflammatory effect in an in vitro model of BPD, such as PCLSs from premature rabbits pretreated with LPS. These encouraging results support the planning of further studies in animal models of BPD and help identify the most effective PBMT protocol to use.