Photobiomodulation Therapy Restores IL-10 Secretion in a Murine Model of Chronic Asthma: Relevance to the Population of CD4+CD25+Foxp3+ Cells in Lung.

Ana Paula Ligeiro de Oliveira,Flávio Aimbire,Aurileia Aparecida de Brito,Renata Kelly da Palma,Karine Zanella Herculano,Tawany Gonçalves Santos,Cristiano Rodrigo de Alvarenga Nascimento,Cintia Estefano-Alves,Maria Cristina Chavantes,Nicole Cristine Rigonato-Oliveira

doi:10.3389/fimmu.2021.789426

Abstract

It is largely known that photobiomodulation (PBM) has beneficial effects on allergic pulmonary inflammation. Our previous study showed an anti-inflammatory effect of the PBM in an acute experimental model of asthma, and we see that this mechanism is partly dependent on IL-10. However, it remains unclear whether the activation of regulatory T cells is mediated by PBM in a chronic experimental model of asthma. In this sense, the objective of this study was to verify the anti-inflammatory role of the PBM in the pulmonary inflammatory response in a chronic experimental asthma model. The protocol used for asthma induction was the administration of OVA subcutaneously (days 0 and 14) and intranasally (3 times/week, for 5 weeks). On day 50, the animals were sacrificed for the evaluation of the different parameters. The PBM used was the diode, with a wavelength of 660 nm, a power of 100 mW, and 5 J for 50 s/point, in three different application points. Our results showed that PBM decreases macrophages, neutrophils, and lymphocytes in the bronchoalveolar lavage fluid (BALF). Moreover, PBM decreased the release of cytokines by the lung, mucus, and collagen in the airways and pulmonary mechanics. When we analyzed the percentage of Treg cells in the group irradiated with laser, we verified an increase in these cells, as well as the release of IL-10 in the BALF. Therefore, we conclude that the use of PBM therapy in chronic airway inflammation attenuated the inflammatory process, as well as the pulmonary functional and structural parameters, probably due to an increase in Treg cells.

Highlights

Bronchial asthma is among the most common chronic respiratory diseases [1,2,3]
The results showed a significant increase in the total influx of leukocytes (Figure 1A), as well as in the number of macrophages, lymphocytes, neutrophils, and eosinophils (Figures 1B–E) recovered in BAL in the OVA group when compared to the Basal group
The results showed a significant increase in the levels of the proinflammatory cytokines IL-5 (Figure 2A), IL-4 (Figure 2B), and IL-13 (Figure 2C) and a reduction of IL-10 (Figure 2D) in the supernatant of BAL, in the asthmatic group (OVA) when compared to the Basal group

Summary

Introduction

Bronchial asthma is among the most common chronic respiratory diseases [1,2,3]. This disease generates a pulmonary inflammatory response that is mitigated by non-curative treatments that have serious side effects [4, 5]. Several studies have already demonstrated the effectiveness of PBM therapy in experimental models of acute lung injury [12], asthma [13, 14], COPD [15], and idiopathic pulmonary fibrosis [16] These studies demonstrate in general that the transcutaneous application of laser at low intensity reaches the lungs and positively interferes in the inflammatory/immunological processes of acute lung injury, whether induced by the administration of lipopolysaccharide (LPS) and ovalbumin (OVA), or by intestinal ischemia and reperfusion [17,18,19]. It seems reasonable to us that the success of this therapy depends on a greater understanding of biological processes associated with its anti-inflammatory effects, both in the treatment of lung diseases and in the treatment of other diseases

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Conclusion