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The oral cavity, a unique ecosystem harboring diverse microorganisms, maintains health through a balanced microflora. Disruption may lead to disease, emphasizing the protective role of gingival epithelial cells (GECs) in preventing harm from pathogenic oral microbes. Shifting GECs’ response from proinflammatory to antimicrobial could be a novel strategy for periodontitis. Photobiomodulation therapy (PBMT), a nonpharmacologic host modulatory approach, is considered an alternative to drugs. While the host cell response induced by a single type of pathogen-associated molecular patterns (PAMPs) was widely studied, this model does not address the cellular response to intact microbes that exhibit multiple PAMPs that might modulate the response. Inspired by this, we developed an in vitro model that simulates direct interactions between host cells and intact pathogens and evaluated the effect of PBMT on the response of human gingival keratinocytes (HGKs) to challenge viable oral microbes at both the cellular and molecular levels. Our data demonstrated that LED pretreatment on microbially challenged HGKs with specific continuous wavelengths (red: 615 nm; near-infrared: 880 nm) induced the production of various antimicrobial peptides, enhanced cell viability and proliferation, promoted reactive oxygen species scavenging, and down-modulated proinflammatory activity. The data also suggest a potential explanation regarding the superior efficacy of near-infrared light treatment compared with red light in enhancing antimicrobial activity and reducing cellular inflammation of HGKs. Taken together, the findings suggest that PBMT enhances the overall barrier function of gingival epithelium while minimizing inflammation-mediated breakdown of the underlying structures.
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Assessing recovery of Drosophila melanogaster photoreceptors with different wavelengths of red and infrared light
It has previously been shown that near-infrared light can positively affect the physiology of damaged tissue. This is likely mediated by the modulation of metabolic activity via cytochrome c oxidase (COX), the rate of ATP production, and generation of reactive oxygen species. It has been suggested that this process can be influenced by light, with different wavelengths potentially having different efficacy. The impact of these effects on retinal health is not yet well understood. To answer this question, we first induced photoreceptor damage in the eyes of white mutant D. melanogaster through prolonged exposure to bright light. We then investigated the recovery of retinal health following exposure to different wavelengths of near-infrared light (670, 750, 810, 850, and 950 nm) over the course of 10 days. Retinal health was assessed through electroretinograms and fluorescent imaging of live photoreceptors. We found that all treatments except for 950 nm light facilitated the recovery of the electroretinogram response in previously light-damaged flies — though efficacy varied across treatments. All near-infrared exposed groups showed at least some improvement in retinal organization and auto-fluorescence compared to an untreated recovery control. We also showed that our results do not stem from a fly specific artifact relating to opsin photoconversion. Finally, we made use of a bioassay to show enhanced ATP levels in light treatments. This study represents a much-needed direct comparison of the effect of a multitude of different wavelengths and contributes to an emerging body of literature that highlights the promise of phototherapy.
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- Award ID(s):
- 1856241
- PAR ID:
- 10572145
- Publisher / Repository:
- The Company of Biologists
- Date Published:
- Journal Name:
- Journal of Experimental Biology
- ISSN:
- 0022-0949
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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