Probable positive effects of the photobiomodulation as an adjunctive treatment in COVID-19: A systematic review

Nejatifard M, Asefi S, Jamali R, Hamblin MR, Fekrazad R. Probable positive effects of the photobiomodulation as an adjunctive treatment in COVID-19: A systematic review. Cytokine. 2021 Jan;137:155312. doi: 10.1016/j.cyto.2020.155312. Epub 2020 Oct 12. PMID: 33128927; PMCID: PMC7550078.


Background: COVID-19, as a newly-emerged viral infection has now spread all over the world after originating in Wuhan, China. Pneumonia is the hallmark of the disease, with dyspnea in half of the patients and acute respiratory distress syndrome (ARDS) in up to one -third of the cases. Pulmonary edema, neutrophilic infiltration, and inflammatory cytokine release are the pathologic signs of this disease. The anti-inflammatory effect of the photobiomodulation (PBM) has been confirmed in many previous studies. Therefore, this review study was conducted to evaluate the direct effect of PBM on the acute lung inflammation or ARDS and also accelerating the regeneration of the damaged tissues. The indirect effects of PBM on modulation of the immune system, increasing the blood flow and oxygenation in other tissues were also considered.

Methodology: The databases of PubMed, Cochrane library, and Google Scholar were searched to find the relevant studies. Keywords included the PBM and related terms, lung inflammation, and COVID-19 -related signs. Studies were categorized with respect to the target tissue, laser parameters, and their results.

Results: Seventeen related papers were included in this review. All of them were in animal models. They showed that the PBM could significantly decrease the pulmonary edema, neutrophil influx, and generation of pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), intracellular adhesion molecule (ICAM), reactive oxygen species (ROS), isoform of nitric oxide synthase (iNOS), and macrophage inflammatory protein 2 (MIP-2)).

Conclusion: Our findings revealed that the PBM could be helpful in reducing the lung inflammation and promoting the regeneration of the damaged tissue. PBM can increase the oxygenation indirectly in order to rehabilitate the affected organs. Thus, the infra-red lasers or light-emitting diodes (LEDs) are recommended in this regard.

5. Conclusion from full text

Despite the lack of available studies on the PBM effects on the COVID-19, but it is assumed that the PBM may be a helpful adjunctive treatment in management of the COVID-19 disease. PBM can reduce the lung edema, neutrophil influx and promote the regeneration of the lung tissue and better oxygenation for all the related organs. Infra-red lasers are recommended because of their higher ability for penetration into the lung tissue. Dosimetry of 6.5–7.5 J/cm2 energy density is suitable for the red lasers and an amount of 9.5–10.5 J/cm2 is a suitable dose for the infra-red lasers. Continous mode irradiation at different points of the respiratory system may be helpful in management of the COVID-19 pneumonia. PBM may be used as a preventive approach in the high -risk patients who could receive pre-treatment PBM while being still at a relatively mild stage of the disease. Also, PBM may be considered as a therapeutic approach in the hospitalized patients before their condition worsens sufficiently to require the ICU admission. Therefore, randomized clinical trials should be carried out on the PBM effects for the COVID-19 disease, and indeed some have already been started in various parts of the world.

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