Lactobacillus paracasei KW3110 Mitigates Retinal Damage Caused by Blue Light Exposure

Written by Angeline A. De Leon, Staff Writer. Study findings suggest that L. paracasei KW3110 may have a preventive effect against blue-light-induced retinal degeneration.

Exposure to blue light emitted by electronic devices like computers, smart phones, and tablets has been linked to photoreceptor degeneration and retinal diseases such as age-related macular degeneration (AMD) ¹. Retinal inflammation may play a key role in photoreceptor degeneration ², and some studies suggest that increasing dietary intake of antioxidant-rich foods can help mitigate light-induced retinal damage ³. The related mechanism of action is not yet fully understood, however, recruitment and activation of macrophages (white blood cells of the immune system) is thought to be involved in the retinal degeneration process ⁴. While M1 macrophages cause inflammatory reactions, M2 macrophages are associated with an anti-inflammatory effect ⁵, and animal research indicates that M2 macrophages can help improve retinal cell survival ⁶. Previous work has shown that lactic acid bacterium, Lactobacillus paracasei KW3110 (L. paracasei KW3110), is able to attenuate inflammation ⁷ and may improve ocular disorders associated with electronic screen time ⁸. In a 2018 study ⁹ published in Nutrients, researchers tested the potential of L. paracasei KW3110 to activate M2 macrophages and mitigate blue light-induced retinal degeneration.

In the first portion of the study, bone marrow-derived M2 macrophages were generated by extracting bone marrow cells from albino mice. Cells were then cultured and treated with L. paracasei KW3110 (at concentrations of 0.1, 1, and 10 µg/mL), and levels of interleukin (IL)-10 (an anti-inflammatory cytokine) were measured in cell culture supernatants. IL-10 gene expression was also measured in mesenteric lymph nodes (MLNs) of mice who were administered 50 mg of L. paracasei KW3110. In the second portion of the study, a litter of 18 4-week-old albino male mice was divided into three groups: a non-light exposure control group receiving a standard rodent diet, a light exposure group receiving a standard rodent diet, and a light exposure group receiving a standard rodent diet containing ~1 mg heat-killed L. paracasei KW3110. After two weeks, mice in the light exposure groups were exposed to 5000 lux of blue light for 3 hours daily for one week. Retinal cells were then harvested, and flow cytometry analyses were used to evaluate inflammatory cytokine production. The outer nuclear layer (ONL) thickness was also measured in sectioned retinal tissue as a marker of photoreceptor integrity.

Overall results revealed a prophylactic effect associated with L. paracasei KW3110: L. paracasei KW3110 at 1 and 10 µg/mL induced significant increases in IL-10 production (p < 0.01 for both), indicative of M2 macrophage activation. Relative gene expression of IL-10 also significantly increased in MLNs 6 hours following oral administration of L. paracasei KW3110 (p < 0.01). Relative to the control group, L. paracasei KW3110 mice showed significantly reduced expressions of inflammatory cytokine, tumor necrosis factor-α (TNF-α), in retinal macrophages following light exposure (p < 0.05). Finally, in mice that were exposed to blue light, intake of L. paracasei KW3110 was associated with preserved ONL thickness, comparable to that of the non-exposed control group, whereas blue light exposed mice that were fed a standard diet showed significantly reduced ONL thickness, relative to light exposed mice that were administered L. paracasei KW3110.

As a whole, findings support the potential of L. paracasei KW3110 to prevent retinal degeneration associated with blue-light exposure. In vitro and in vivo experiments revealed that L. paracasei KW3110 was capable of activating M2 macrophages, inducing anti-inflammatory cytokine production and increasing IL-10 mRNA expression. Probiotic supplementation also suppressed the production of inflammatory cytokines associated with blue light exposure, and by preserving retinal thickness, L. paracasei KW3110 effectively attenuated light-induced photoreceptor degeneration. Thus, L. paracasei KW3110 demonstrates favorable effects on retinal function and morphology and should be considered as a potential therapeutic agent against degenerative retinal diseases. Further testing in larger animals and human subjects is warranted.

Source: Morita Y, Miwa Y, Jounai K, et al. Lactobacillus paracasei KW3110 prevents blue light-induced inflammation and degeneration in the retina. Nutrients. 2018; 10: 1991. DOI: 10.3390/nu10121991.

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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Posted May 11, 2020.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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