The Probable Protective Effect of Photobiomodulation on the Inflammation of the Airway and Lung in COVID-19 Treatment: A Preclinical and Clinical Meta-Analysis.

Preliminary studies also show that many of the fatalities of COVID-19 are due to over-activity of the immune system, and photobiomodulation (PBM) therapy mainly accelerates wound healing and reduces pain and inflammation. Therefore, this systematic review and meta-analysis was conducted to evaluate the probable effect of the PBM therapy on the lung inflammation or ARDS and accelerate the regeneration of the damaged tissue. We systematically searched major indexing databases, including PubMed/Medline, ISI web of science (WOS), Scopus, Embase, and Cochrane central, using standard terms without any language, study region, or type restrictions. Of the 438 studies found through initial searches, 13 met the inclusion criteria. After applying the exclusion criteria, the main properties of 13 articles on 384 animals included in this meta-analysis with a wide range of species include rat (n = 10) and rabbit (n = 3). The analysis revealed that PBM therapy reduced TNFα (SMD:-3.75, 95% CI: -4.49, -3.02, P < 0.00001, I 2  = 10%), IL-1β (SMD:-4.65, 95% CI: -6.15, -3.16, P < 0.00001, I 2  = 62%), and IL-6 (SMD:-4.20, 95% CI: -6.42, -1.97, P = 0.0002, I 2  = 88%) significantly compared with the model controls. Hence, PBM therapy increased IL-10 significantly compared with the model controls (SMD:-4.65, 95% CI: -6.15, -3.16, P < 0.00001, I 2  = 62%). PBM therapy also reduced MPO activity (SMD:-2.13, 95% CI: -3.38, -0.87, P = 0.0009, I 2  = 64%) and vascular permeability (SMD:-2.59, 95% CI: -4.40, -0.77, P = 0.0052, I 2  = 71%) in the lung using the Evans blue extravasation technique significantly compared with the model controls. This systematic review and meta-analysis revealed that the PBM therapy does utilize beneficial anti-inflammatory effect, modulation of the immune system, lung permeability, or bronchoalveolar lavage on lung damage in both animal models and clinical studies. However, animal model and clinical studies appear limited considering the quality of the included evidences; therefore, large clinical trials are still required.