Comparative assessment of antimicrobial, antiradical and cytotoxic activities of cannabidiol and its propyl analogue cannabidivarin

Cannabidiol and cannabidivarin are phytocannabinoids produced by Cannabis indica and Cannabis sativa. Cannabidiol has been studied more extensively than its propyl analogue cannabidivarin. Therefore, we performed a battery of in vitro biological assays to compare the cytotoxic, antiradical and antibacterial activities of both cannabinoids. Potential mitochondrial metabolism alterations, DNA synthesis inhibition, and plasma membrane damage were studied by MTT assay, BrdU-ELISA and LDH assay of cancer and normal human cells exposed to cannabinoids. ABTS and DPPH assays were performed to observe the effects of the cannabinoids on free radicals. Microbial susceptibility tests were performed to study the activity of the cannabinoids in two bacterial species implicated in human infections, Escherichia coli and Staphylococcus aureus. The results showed that the cannabinoids induced medium levels of cytotoxicity in cancer and normal cells at concentrations ranging from 15.80 to 48.63 and from 31.89 to 151.70 µM, respectively, after 72 h of exposure. Cannabinoids did not exhibit a strong antioxidant capacity in scavenging ABTS or DPPH radicals. No evident differences were observed between the two cannabinoids in antimicrobial activity, except with respect to S. aureus, which showed greater susceptibility to cannabidiol than to cannabidivarin after 72 h of exposure.

Prediction and Utilization of Malondialdehyde in Exotic Pine Under Drought Stress Using Near-Infrared Spectroscopy

Drought is a major abiotic stress that adversely affects the growth and productivity of plants. Malondialdehyde (MDA), a substance produced by membrane lipids in response to reactive oxygen species (ROS), can be used as a drought indicator to evaluate the degree of plasma membrane damage and the ability of plants to drought stress tolerance. Still measuring MDA is usually a labor- and time-consuming task. In this study, near-infrared (NIR) spectroscopy combined with partial least squares (PLS) was used to obtain rapid and high-throughput measurements of MDA, and the application of this technique to plant drought stress experiments was also investigated. Two exotic conifer tree species, namely, slash pine (Pinus elliottii) and loblolly pine (Pinus taeda), were used as plant material exposed to drought stress; different types of spectral preprocessing methods and important feature-selection algorithms were applied to the PLS model to calibrate it and obtain the best MDA-predicting model. The results show that the best PLS model is established via the combined treatment of detrended variable–significant multivariate correlation algorithm (DET-sMC), where latent variables (LVs) were 6. This model has a respectable predictive capability, with a correlation coefficient (R2) of 0.66, a root mean square error (RMSE) of 2.28%, and a residual prediction deviation (RPD) of 1.51, and it was successfully implemented in drought stress experiments as a reliable and non-destructive method to detect the MDA content in real time.

Real-time studies of plasma membrane damage trigger cell apoptosis from sulfhydryl nanoparticles to support safety assessment of nanoscale materials

Background: Sulfhydryl groups are present on the surface of nanoparticles in unburned vehicle exhaust and most air pollutants produced by combustion, which raises the risk for exposure of human. Sulfhydride nanoparticles not only penetrate the skin range from the stratum corneum to pass below the dermis, they also entering the systemis circulation from cell endocytosis pass way. The potential risk of skin and body healthy associated from sulfhydride nanoparticles were attach much attentions. It is important to illuminate the underlying toxicity of sulfhydride nanoparticles to humanbody, but the mechanisms underlying the toxicity of nanoparticles on cells remain unclear, especially the relationship from the damage of cells plasma membrane and the cell cycle.Methods: We performed time-response studies and cells-membrane interaction studies in C6 cells to observe the effects of 50nm and 200nm sulfhydryl nanoparticles on the activities, cell metabolism and cell cycle. The cells were exposed to 0, 10 or 20 Nano particles for 12, 36, 24, 48 or 72h to finish the particle- response studies. On the time of treatment, cells were collected to assess the expression of tight junction-associated proteins, P21, FBW7 and cyclin E. To further investigate the mechanisms underlying nanoparticle-induced dysregulation of tight junction-associated protein, we studied the change of lipid bilayers. Sum frequency generation optic spectrum was carried out to study the membrane change. Results: The results show that the smaller particles penetrate the plasma membrane and without bilayer disruption, whereas the larger one will pilled off one leaflet of the membrane, they are mostly trapped in endosomes. The larger ones result in slow but unrepairable cell necrosis and caused cell cycle regulation disorders via disturbing the expression of p21, cyclin E, and FBW-7. Conclusion: The results suggest that the destruction of membrane structure by the particles will cause irreversible biological damage, and particles entering cells through protein assisted process will increase the expression of cell cycle related proteins and cells self-repair can be observed from the in vitro experiments. From the interactions between mitochondria lipid model and nanoparticles, we deduced that, the efficiencies of nano-scaled drugs could be enhanced by altering the interaction models of nano systems and mitochondria. In the future, mitochondria membrane proteins would also be carefully explored to confirm their roles in the active mitochondrial uptake of nanoparticles and provide new channels for safe and effective mitochondria targeting drug delivery. Real-time studies of plasma membrane damage from sulfhydryl nanoparticles, and analysis the triggering of cell apoptosis, will support safety assessment of nanoscale materials.

Ferroptosis in infection, inflammation, and immunity

Ferroptosis is a type of regulated necrosis that is triggered by a combination of iron toxicity, lipid peroxidation, and plasma membrane damage. The upstream inducers of ferroptosis can be divided into two categories (biological versus chemical) and activate two major pathways (the extrinsic/transporter versus the intrinsic/enzymatic pathways). Excessive or deficient ferroptotic cell death is implicated in a growing list of physiological and pathophysiological processes, coupled to a dysregulated immune response. This review focuses on new discoveries related to how ferroptotic cells and their spilled contents shape innate and adaptive immunity in health and disease. Understanding the immunological characteristics and activity of ferroptotic death not only illuminates an intersection between cell death and immunity but may also lead to the development of novel treatment approaches for immunopathological diseases.

Plasma membrane integrity: implications for health and disease

Plasma membrane integrity is essential for cellular homeostasis. In vivo, cells experience plasma membrane damage from a multitude of stressors in the extra- and intra-cellular environment. To avoid lethal consequences, cells are equipped with repair pathways to restore membrane integrity. Here, we assess plasma membrane damage and repair from a whole-body perspective. We highlight the role of tissue-specific stressors in health and disease and examine membrane repair pathways across diverse cell types. Furthermore, we outline the impact of genetic and environmental factors on plasma membrane integrity and how these contribute to disease pathogenesis in different tissues.

Plasma membrane damage limits replicative lifespan in yeast and human fibroblasts

Plasma membrane damage (PMD) occurs in all cell types due to environmental perturbation and cell-autonomous activities. However, cellular outcomes of PMD remain largely unknown except for recovery or death. Here, using yeast and human fibroblasts, we show that cellular senescence, irreversible cell cycle arrest contributing to organismal aging, is the third outcome of PMD. To identify the genes essential for PMD response, we performed a systematic yeast genome-wide screen. The screen identified 48 genes. The top hits in the screen are the endosomal sorting complexes required for transport (ESCRT) genes. Strikingly, the replicative lifespan regulator genes are enriched in our 48 hits, and indeed, PMD limits the replicative lifespan in budding yeast; the ESCRT activator AAA-ATPase VPS4-overexpression extends it. In normal human fibroblasts, PMD induces cellular senescence via p53. Our study demonstrates that PMD limits replicative lifespan in two different eukaryotic cell types and highlights an underappreciated but ubiquitous senescent cell subtype, namely PMD-dependent senescent cells.

A cryo–electron tomography workflow reveals protrusion-mediated shedding on injured plasma membrane

Cryo–electron tomography (cryo-ET) provides structural context to molecular mechanisms underlying biological processes. Although straightforward to implement for studying stable macromolecular complexes, using it to locate short-lived structures and events can be impractical. A combination of live-cell microscopy, correlative light and electron microscopy, and cryo-ET will alleviate this issue. We developed a workflow combining the three to study the ubiquitous and dynamic process of shedding in response to plasma membrane damage in HeLa cells. We found filopodia-like protrusions enriched at damage sites and acting as scaffolds for shedding, which involves F-actin dynamics, myosin-1a, and vacuolar protein sorting 4B (a component of the ‘endosomal sorting complex required for transport’ machinery). Overall, shedding is more complex than current models of vesiculation from flat membranes. Its similarities to constitutive shedding in enterocytes argue for a conserved mechanism. Our workflow can also be adapted to study other damage response pathways and dynamic cellular events.

A surfactant polymer wound dressing protects human keratinocytes from inducible necroptosis

Chronic wounds show necroptosis from which keratinocytes must be protected to enable appropriate wound re-epithelialization and closure. Poloxamers, a class of synthetic triblock copolymers, are known to be effective against plasma membrane damage (PMD). The purpose of this study is to evaluate the efficacy of a specific poloxamer, surfactant polymer dressing (SPD), which is currently used clinically as wound care dressing, against PMD in keratinocytes. Triton X-100 (TX100) at sub-lytic concentrations caused PMD as demonstrated by the efflux of calcein and by the influx of propidium iodide and FM1-43. TX100, an inducer of necroptosis, led to mitochondrial fragmentation, depletion of nuclear HMGB1, and activation of signaling complex associated with necroptosis (i.e., activation of RIP3 and phosphorylation of MLKL). All responses following exposure of human keratinocytes to TX100 were attenuated by pre- or co-treatment with SPD (100 mg/ml). The activation and translocation of phospho-MLKL to the plasma membrane, taken together with depletion of nuclear HMGB1, characterized the observed cell death as necroptosis. Thus, our findings show that TX100-induced plasma membrane damage and death by necroptosis were both attenuated by SPD, allowing keratinocyte survival. The significance of such protective effects of SPD on keratinocytes in wound re-epithelialization and closure warrant further studies.