IL-6-Mediated Upregulated miRNAs in Extracellular Vesicles Derived from Lund Human Mesencephalic (LUHMES) Cells: Effects on Astrocytes and Microglia.

Psychological stress plays a major role in depression, and interleukin-6 (IL-6) is elevated during depression and psychological stress. MicroRNAs (miRNAs) in extracellular vesicles (EVs), including exosomes and microvesicles, suppress mRNA expression in other cells when endocytosed. In this study, we analyzed the effect of IL-6 on EVs secreted by neural precursor cells. Cells from the human immortalized neural precursor cell line LUHMES were treated with IL-6. EVs were collected using a nanofiltration method. We then analyzed the uptake of LUHMES-derived EVs by astrocytes (ACs) and microglia (MG). Microarray analysis of miRNAs was performed using EV-incorporated RNA and intracellular RNA from ACs and MG to search for increased numbers of miRNAs. We applied the miRNAs to ACs and MG, and examined the cells for suppressed mRNAs. IL-6 increased several miRNAs in the EVs. Three of these miRNAs were originally low in ACs and MG (hsa-miR-135a-3p, hsa-miR-6790-3p, and hsa-miR-11399). In ACs and MG, hsa-miR-6790-3p and hsa-miR-11399 suppressed four mRNAs involved in nerve regeneration (NREP, KCTD12, LLPH, and CTNND1). IL-6 altered the types of miRNAs in EVs derived from neural precursor cells, by which mRNAs involved in nerve regeneration were decreased in ACs and MG. These findings provide new insights into the involvement of IL-6 in stress and depression.

Advanced light-tolerant microalgae-nitrifying bacteria consortia for stable ammonia removal under strong light irradiation using light-shielding hydrogel.

The consortium of microalgae and nitrifying bacteria has attracted attention owing to its advantages, such as energy- and cost-efficiency in terms of using only light irradiation without aeration. However, high light intensity can easily cause photoinhibition of nitrifying bacteria, resulting in process breakdown of the consortium. This challenge limits its practical application in outdoor environment. In a previous study, we developed a "light-shielding hydrogel" which entrapped nitrifying bacteria in carbon black-added alginate hydrogel beads and confirmed its effectiveness of protecting the nitrifying bacteria from intense light up to 1600 µmol photons m-2 s-1. However, the applicability of the light-shielding hydrogel to microalgae-nitrifying bacteria consortia under strong light irradiation has not yet been clarified. In this study, we aimed to establish consortia of Chlorella sorokiniana and nitrifying bacteria immobilised in light-shielding hydrogel and evaluate their nitrification performance under strong light. Three nitrifying bacteria conditions were used: light-shielding hydrogel, hydrogel containing only nitrifying bacteria without carbon black ('hydrogel'), and dispersed nitrifier without immobilisation ('dispersion') as a control. At 1600 µmol photons m-2 s-1, the dispersion afforded a significant decrease in nitrification activity and subsequent process breakdown. In contrast, light-shielding hydrogel achieved complete nitrification without nitrite accumulation and had nitrification rates of approximately nine and two times higher than those for the dispersion and hydrogel conditions, respectively. Based on the overall evaluation, a possible sequence of process breakdown under strong light was also proposed. This study demonstrated for the first time that the light-shielding hydrogel/consortia combination had potential for applications, which require mitigation of photoinhibition under strong light irradiation. Further, it is expected that the proposed method will contribute to realise the practical application of microalgae-nitrifying bacteria consortia in various countries that experience high sunlight intensity due to their location in the sunbelt areas.