Exploring Immune Modulatory Effects of Cyclotide-Enriched Viola tricolor Preparations

Viola tricolor is a medicinal plant with documented application as an anti-inflammatory herb. The standard of care for the treatment of inflammatory bowel disease is immunosuppressive therapeutics or biologics, which often have undesired effects. We explored V. tricolor herbal preparations that are rich in an emerging class of phytochemicals with drug-like properties, so-called cyclotides. As an alternative to existing inflammatory bowel disease medications, cyclotides have immunomodulatory properties, and their intrinsic stability allows for application in the gastrointestinal tract, for instance, via oral administration. We optimized the isolation procedure to improve the yield of cyclotides and compared the cellular effects of violet-derived organic solvent-extracts, aqueous preparations, and an isolated cyclotide from this plant on primary human T lymphocytes and macrophages, i.e., cells that are crucial for the initiation and progression of inflammatory bowel disease. The hot water herbal decoctions have a stronger immunosuppressive activity towards proliferation, interferon-γ, and interleukin-21 secretion of primary human T cells than a DCM/MeOH cyclotide-enriched extract, and the isolated cyclotide kalata S appears as one of the active components responsible for the observed effects. This effect was increased by a longer boiling duration. In contrast, the DCM/MeOH cyclotide-enriched extract was more effective in reducing the levels of cytokines interleukin-6, interleukin-12, interleukin-23, tumor necrosis factor-α, and C - X-C motif chemokine ligand 10, secreted by human monocyte-derived macrophages. Defined cyclotide preparations of V. tricolor have promising pharmacological effects in modulating immune cell responses at the cytokine levels. This is important towards understanding the role of cyclotide-containing herbal drug preparations for future applications in immune disorders, such as inflammatory bowel disease.

Effects of temperature on seed dormancy and germination of the coastal dune plant Viola grayi: germination phenology and responses to winter warming

PREMISE

In temperate sand dunes, rising air temperature from climate change could not only further elevate surface soil temperatures during summers, but also drastically change the range of soil temperatures in other seasons. Winter warming may shift the timing of seed germination of dune species that require cold stratification for dormancy release.

METHODS

We assessed the effects of temperature on dormancy and germination of Viola grayi seeds and evaluated whether winter warming could affect its germination phenology by conducting germination experiments and analyzing soil temperature data in cold and warm winters.

RESULTS

Viola grayi seeds were dormant when dispersed in spring. One-month moist-chilling treatment (4°C) effectively released dormancy, while short, intermittent lower temperatures (alternating 20°/5°C) did not. Continuous higher temperatures induced secondary dormancy in nondormant seeds. During a cold, snowy winter, the surface soil temperatures of the sand dune remained at 0°-2°C for approximately 1 month owing to the accumulated snow, while the period of such stable low soil temperatures was much shorter during a warm, less-snowy winter, and the highest soil temperature reached 20°-25°C. These results suggest that dispersed seeds germinate in the following spring after winter chilling, but they may remain dormant after warm winters.

CONCLUSIONS

With winter warming, seed dormancy of V. grayi seeds could be prolonged and the associated germination delayed. Assessing the minimum requirements for dormancy release and the potential to form persistent soil seed banks is important for judging the necessity and urgency of conservation efforts for temperate dune species.

Improved resolution in extracellular vesicle populations using 405 instead of 488 nm side scatter

Improvements in identification and assessment of extracellular vesicles (EVs) have fuelled a recent surge in EV publications investigating their roles as biomarkers and mediators of disease. Meaningful scientific comparisons are, however, hampered by difficulties in accurate, reproducible enumeration and characterization of EVs in biological fluids. High-sensitivity flow cytometry (FCM) is presently the most commonly applied strategy to assess EVs, yet its utility is limited by variant ability to resolve smaller EVs. Here, we propose the use of 405 nm (violet) wavelength lasers in place of 488 nm (blue) for side scatter (SSC) detection to obtain greater resolution of EVs using high-sensitivity FCM. To test this hypothesis, we modelled EV resolution by violet versus blue SSC in silico and compared resolution of reference beads and biological EVs from plasma and bronchoalveolar lavage (BAL) fluid using either violet or blue wavelength SSC EV detection. Mie scatter modelling predicted that violet as compared to blue SSC increases resolution of small (100–500 nm) spherical particles with refractive indices (1.34–1.46) similar to EVs by approximately twofold in terms of light intensity and by nearly 20% in SSC signal quantum efficiency. Resolution of reference beads was improved by violet instead of blue SSC with two- and fivefold decreases in coefficients of variation for particles of 300–500 nm and 180–240 nm size, respectively. Resolution was similarly improved for detection of EVs from plasma or BAL fluid. Violet SSC detection for high-sensitivity FCM allows for significantly greater resolution of EVs in plasma and BAL compared to conventional blue SSC and particularly improves resolution of smaller EVs. Notably, the proposed strategy is readily implementable and inexpensive for machines already equipped with 405 nm SSC or the ability to accommodate 405/10 nm bandpass filters in their violet detector arrays.