Marine biogenics in sea spray aerosols interact with the mTOR signaling pathway

Re-thinking human interactions with the oceans

Earth's marine ecosystems are changing rapidly, in large part owing to the damaging effects of human activities. Unless humans find better ways of interacting with the seas and oceans, the marine resources upon which we rely will diminish as more ecosystems collapse. The consequences for human health and wellbeing will be severe. The meta-discipline of Oceans and Human Health has catalogued how the oceans and their constituents benefit human lives. Examples include access to seafood, pharmaceuticals and physical and mental health benefits. This interdisciplinary research effort has also revealed how the integrated impact of anthropogenic activities has disrupted ocean processes resulting in extensive losses of marine biodiversity, increasing chemical and microbial pollution, proliferation of harmful algal blooms and increased coastal inundation, all of which threaten human populations. In response, non-governmental organizations and national governments have established various agreements and treaties to prevent further damage, restore what has been lost and grasp new economic opportunities. Nevertheless, ocean-related risks continue to escalate rapidly in the absence of political commitment. New thinking regarding the interconnectedness of all human/ocean interactions is required to remove the barriers and impediments that hamper tackling the wicked problem of fostering health and wellbeing while achieving ocean sustainability.

Genetically encoded fluorescent sensors for visualizing polyamine levels, uptake, and distribution

Polyamines are abundant and physiologically essential biomolecules that play a role in numerous processes, but are disrupted in diseases such as cancer, and cardiovascular and neurological disorders. Despite their importance, measuring free polyamine concentrations and monitoring their metabolism and uptake in cells in real-time remains impossible due to the lack of appropriate biosensors. Here we engineered, characterized, and validated the first genetically encoded biosensors for polyamines, named iPASnFRs. We demonstrate the utility of iPASnFR for detecting polyamine import into mammalian cells, to the cytoplasm, mitochondria, and the nucleus. We demonstrate that these sensors are useful to probe the activity of polyamine transporters and to uncover biochemical pathways underlying the distribution of polyamines amongst organelles. The sensors powered a high-throughput small molecule compound library screen, revealing multiple compounds in different chemical classes that strongly modulate cellular polyamine levels. These sensors will be powerful tools to investigate the complex interplay between polyamine uptake and metabolic pathways, address open questions about their role in health and disease, and enable screening for therapeutic polyamine modulators.

The immunostimulatory activity of sea spray aerosols: bacteria and endotoxins activate TLR4, TLR2/6, NF-κB and IRF in human cells

Frequent exposure to sea spray aerosols (SSA) containing marine microorganisms and bioactive compounds may influence human health. However, little is known about potential immunostimulation by SSA exposure. This study focuses on the effects of marine bacteria and endotoxins in SSA on several receptors and transcription factors known to play a key role in the human innate immune system. SSA samples were collected in the field (Ostend, Belgium) or generated in the lab using a marine aerosol reference tank (MART). Samples were characterized by their sodium contents, total bacterial counts, and endotoxin concentrations. Human reporter cells were exposed to SSA to investigate the activation of toll-like receptor 4 (TLR4) in HEK-Blue hTLR4 cells and TLR2/6 in HEK-Blue hTLR2/6 cells, as well as the activation of nuclear factor kappa B (NF-κB) and interferon regulatory factors (IRF) in THP1-Dual monocytes. These responses were then correlated to the total bacterial counts and endotoxin concentrations to explore dose-effect relationships. Field SSA contained from 3.0 × 103 to 6.0 × 105 bacteria/m3 air (averaging 2.0 ± 1.9 × 105 bacteria/m3 air) and an endotoxin concentration ranging from 7 to 1217 EU/m3 air (averaging 389 ± 434 EU/m3 air). In contrast, MART SSA exhibited elevated levels of total bacterial count (from 2.0 × 105 to 2.4 × 106, averaging 7.3 ± 5.5 × 105 cells/m3 air) and endotoxin concentration from 536 to 2191 (averaging 1310 ± 513 EU/m3 air). SSA samples differentially activated TLR4, TLR2/6, NF-κB and IRF. These immune responses correlated dose-dependently with the total bacterial counts, endotoxin levels, or both. This study sheds light on the immunostimulatory potential of SSA and its underlying mechanisms, highlighting the need for further research to deepen our understanding of the health implications of SSA exposure.

Systematic Review: Neurodevelopmental Benefits of Active/Passive School Exposure to Green and/or Blue Spaces in Children and Adolescents

Today more than half of the world's population lives in urban areas. Children spend about 40 h a week in the school environment. Knowing the influence of school exposure to green/blue spaces could improve the children's health, creating healthier environments and preventing exposure to legal/illegal drugs. This systematic review summarized the main results of published studies on active or passive exposure to green or blue spaces in different domains of child neurodevelopment. In August 2022, five databases were searched and twenty-eight eligible studies were included in the analysis. Cognitive and/or academic performance was the most frequently studied (15/28). Most studies evaluate passive exposure to green/blue spaces (19/28) versus active exposure (9/28). Only three studies addressed the relationship between blue space and neurodevelopment. The main results point toward mixed evidence of a protective relationship between green/blue space exposure and neurodevelopment, especially in improving cognitive/academic performance, attention restoration, behavior, and impulsivity. Renaturalizing school spaces and promoting "greener" capacities for school environmental health could improve children's neurodevelopment. There was great heterogeneity in methodologies and adjustment for confounding factors across studies. Future research should seek a standardized approach to delivering school environmental health interventions beneficial to children's development.

Acanthaster planci Inhibits PCSK9 Gene Expression via Peroxisome Proliferator Response Element (PPRE) and Activation of MEK and PKC Signaling Pathways in Human Liver Cells

A constantly elevated level of low-density lipoprotein cholesterol (LDL-C) is mainly associated with the development of atherosclerosis. The use of statins as a treatment for reducing plasma LDL-C levels has led, in some cases, to adverse side effects, including a decrease in hepatic LDL receptor (LDLR), the receptor responsible for the uptake of circulating LDL-C. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is an enzyme responsible for directing the LDLR–LDL-C complex to lysosomal degradation upon transport into cells, preventing the recycling of LDLR to the cell surface. Therefore, PCSK9 may offer a new target for reducing the levels of plasma LDL-C. In this study, we investigated the mechanisms of action of a selected fraction of A. planci on PCSK9 gene expression, as well as the effect of the fraction on the level of LDLR protein and the uptake of LDL-C. Using real-time PCR, it was shown that the selected A. planci fraction reduced the gene expression of PCSK9 in human liver HepG2 cells. Immunocytochemistry analysis demonstrated that the selected A. planci fraction increased the LDLR protein level and LDL-C uptake in HepG2 cells. Promoter mutational and gene expression analyses revealed that PPRE, a binding site for peroxisome proliferator–activated receptor (PPAR), was responsible for mediating the inhibitory effect of the selected fraction on PCSK9 mRNA. In addition, MAP kinase and PKC components of the signal transduction pathway were activated, inducing the action of the selected A. planci fraction in decreasing PCSK9 gene expression. These findings suggest that the selected fraction shows good potential for reducing circulating LDL-C and, thus, may be a good therapeutic intervention to prevent the progression of atherosclerosis.

Sea Spray Aerosols Contain the Major Component of Human Lung Surfactant

Marine phytoplankton influence the composition of sea spray aerosols (SSAs) by releasing various compounds. The biogenic surfactant dipalmitoylphosphatidylcholine (DPPC) is known to accumulate in the sea surface microlayer, but its aerosolization has never been confirmed. We conducted a 1 year SSA sampling campaign at the Belgian coast and analyzed the SSA composition. We quantified DPPC at a median and maximum air concentration of 7.1 and 33 pg m^-3, respectively. This discovery may be of great importance for the field linking ocean processes to human health as DPPC is the major component of human lung surfactant and is used as excipient in medical aerosol therapy. The natural airborne exposure to DPPC seems too low to induce direct human health effects but may facilitate the effects of other marine bioactive compounds. By analyzing various environmental variables in relation to the DPPC air concentration, using a generalized linear model, we established that wave height is a key environmental predictor and that it has an inverse relationship. We also demonstrated that DPPC content in SSAs is positively correlated with enriched aerosolization of Mg²⁺ and Ca²⁺. In conclusion, our findings are not only important from a human health perspective but they also advance our understanding of the production and composition of SSAs.

Phycotoxin-Enriched Sea Spray Aerosols: Methods, Mechanisms, and Human Exposure

To date, few studies have examined the role of sea spray aerosols (SSAs) in human exposure to harmful and beneficial marine compounds. Two groups of phycotoxins (brevetoxins and ovatoxins) have been reported to induce respiratory syndromes during harmful algal blooms. The aerosolization and coastal air concentrations of other common marine phycotoxins have, however, never been examined. This study provides the first (experimental) evidence and characterization of the aerosolization of okadaic acid (OA), homoyessotoxin, and dinophysistoxin-1 using seawater spiked with toxic algae combined with the realistic SSA production in a marine aerosol reference tank (MART). The potential for aerosolization of these phycotoxins was highlighted by their 78- to 1769-fold enrichment in SSAs relative to the subsurface water. To obtain and support these results, we first developed an analytical method for the determination of phycotoxin concentrations in SSAs, which showed good linearity (R² > 0.99), recovery (85.3-101.8%), and precision (RSDs ≤ 17.2%). We also investigated natural phycotoxin air concentrations by means of in situ SSA sampling with concurrent aerosolization experiments using natural seawater in the MART. This approach allowed us to indirectly quantify the (harmless) magnitude of OA concentrations (0.6-51 pg m^-3) in Belgium's coastal air. Overall, this study provides new insights into the enriched aerosolization of marine compounds and proposes a framework to assess their airborne exposure and effects on human health.

Blue space, health and well-being: A narrative overview and synthesis of potential benefits

Research into the potential health and well-being benefits from exposure to green spaces such as parks and woodlands has led to the development of several frameworks linking the different strands of evidence. The current paper builds on these to provide a model of how exposure to aquatic environments, or blue spaces such as rivers, lakes and the coast, in particular, may benefit health and well-being. Although green and blue spaces share many commonalities, there are also important differences. Given the breadth of the research, spanning multiple disciplines and research methodologies, a narrative review approach was adopted which aimed to highlight key issues and processes rather than provide a definitive balance of evidence summary. Novel aspects of our framework included the inclusion of outcomes that are only indirectly good for health through being good for the environment, the addition of nature connectedness as both a trait and state, and feedback loops where actions/interventions to increase exposure are implemented. Limitations of the review and areas for future work, including the need to integrate potential benefits with potential risks, are discussed.

CAICE Studies: Insights from a Decade of Ocean-Atmosphere Experiments in the Laboratory

Ocean-atmosphere interactions control the composition of the atmosphere, hydrological cycle, and temperature of our planet and affect human and ecosystem health. Our understanding of the impact of ocean emissions on atmospheric chemistry and climate is limited relative to terrestrial systems, despite the fact that oceans cover the majority (71%) of the Earth. As a result, the impact of marine aerosols on clouds represents one of the largest uncertainties in our understanding of climate, which is limiting our ability to accurately predict the future temperatures of our planet. The emission of gases and particles from the ocean surface constitutes an important chemical link between the ocean and atmosphere and is mediated by marine biological, physical, and chemical processes. It is challenging to isolate the role of biological ocean processes on atmospheric chemistry in the real world, which contains a mixture of terrestrial and anthropogenic emissions. One decade ago, the NSF Center for Aerosol Impacts on Chemistry of the Environment (CAICE) took a unique ocean-in-the-laboratory approach to study the factors controlling the chemical composition of marine aerosols and their effects on clouds and climate. CAICE studies have demonstrated that the complex interplay of phytoplankton, bacteria, and viruses exerts significant control over sea spray aerosol composition and the production of volatile organic compounds. In addition, CAICE experiments have explored the physical production mechanisms and their impact on the properties of marine cloud condensation nuclei and ice nucleating particles, thus shedding light on connections between the oceans and cloud formation. As these ocean-in-the-laboratory experiments become more sophisticated, they allow for further exploration of the complexity of the processes that control atmospheric emissions from the ocean, as well as incorporating the effects of atmospheric aging and secondary oxidation processes. In the face of unprecedented global climate change, these results provide key insights into how our oceans and atmosphere are responding to human-induced changes to our planet.This Account presents results from a decade of research by chemists in the NSF Center for Aerosol Impacts on Chemistry of the Environment. The mission of CAICE involves taking a multidisciplinary approach to transform the ability to accurately predict the impact of marine aerosols on our environment by bringing the full real-world chemical complexity of the ocean and atmosphere into the laboratory. Toward this end, CAICE has successfully advanced the study of the ocean-atmosphere system under controlled laboratory settings through the stepwise simulation of physical production mechanisms and incorporation of marine microorganisms, building to systems that replicate real-world chemical complexity. This powerful approach has already made substantial progress in advancing our understanding of how ocean biology and physical processes affect the composition of nascent sea spray aerosol (SSA), as well as yielded insights that help explain longstanding discrepancies in field observations in the marine environment. CAICE research is now using laboratory studies to assess how real-world complexity, such as warming temperatures, ocean acidification, wind speed, biology, and anthropogenic perturbations, impacts the evolution of sea spray aerosol properties, as well as shapes the composition of the marine atmosphere.

Lysosomes, Autophagy, and Hormesis in Cell Physiology, Pathology, and Age-Related Disease

Autophagy has been strongly linked with hormesis, however, it is only relatively recently that the mechanistic basis underlying this association has begun to emerge. Lysosomal autophagy is a group of processes that degrade proteins, protein aggregates, membranes, organelles, segregated regions of cytoplasm, and even parts of the nucleus in eukaryotic cells. These degradative processes are evolutionarily very ancient and provide a survival capability for cells that are stressed or injured. Autophagy and autophagic dysfunction have been linked with many aspects of cell physiology and pathology in disease processes; and there is now intense interest in identifying various therapeutic strategies involving its regulation. The main regulatory pathway for augmented autophagy is the mechanistic target of rapamycin (mTOR) cell signaling, although other pathways can be involved, such as 5'-adenosine monophosphate-activated protein kinase. Mechanistic target of rapamycin is a key player in the many highly interconnected intracellular signaling pathways and is responsible for the control of cell growth among other processes. Inhibition of mTOR (specifically dephosphorylation of mTOR complex 1) triggers augmented autophagy and the search is on the find inhibitors that can induce hormetic responses that may be suitable for treating many diseases, including many cancers, type 2 diabetes, and age-related neurodegenerative conditions.

General health and residential proximity to the coast in Belgium: Results from a cross-sectional health survey

The health risks of coastal areas have long been researched, but the potential benefits for health are only recently being explored. The present study compared the general health of Belgian citizens a) according to the EU's definition of coastal (<50 km) vs. inland (>50 km), and b) between eight more refined categories of residential proximity to the coast (<5 km to >250 km). Data was drawn from the Belgian Health Interview Survey (n = 60,939) and investigated using linear regression models and mediation analyses on several hypothesized mechanisms. Results indicated that populations living <5 km of the coast reported better general health than populations living at >50-100 km. Four commonly hypothesized mechanisms were considered but no indirect associations were found: scores for mental health, physical activity levels and social contacts were not higher at 0-5 km from the coast, and air pollution (PM₁₀ concentrations) was lower at 0-5 km from the coast but not statistically associated with better health. Results are controlled for typical variables such as age, sex, income, neighbourhood levels of green and freshwater blue space, etc. The spatial urban-rural-nature mosaic at the Belgian coast and alternative explanations are discussed. The positive associations between the ocean and human health observed in this study encourage policy makers to manage coastal areas sustainably to maintain associated public health benefits into the future.

Aerosolizable Marine Phycotoxins and Human Health Effects: In Vitro Support for the Biogenics Hypothesis

Respiratory exposure to marine phycotoxins is of increasing concern. Inhalation of sea spray aerosols (SSAs), during harmful Karenia brevis and Ostreopsis ovata blooms induces respiratory distress among others. The biogenics hypothesis, however, suggests that regular airborne exposure to natural products is health promoting via a downregulation of the mechanistic target of rapamycin (mTOR) pathway. Until now, little scientific evidence supported this hypothesis. The current explorative in vitro study investigated both health-affecting and potential health-promoting mechanisms of airborne phycotoxin exposure, by analyzing cell viability effects via cytotoxicity assays and effects on the mTOR pathway via western blotting. To that end, A549 and BEAS-2B lung cells were exposed to increasing concentrations (ng·L⁻¹–mg·L⁻¹) of (1) pure phycotoxins and (2) an extract of experimental aerosolized homoyessotoxin (hYTX). The lowest cell viability effect concentrations were found for the examined yessotoxins (YTXs). Contradictory to the other phycotoxins, these YTXs only induced a partial cell viability decrease at the highest test concentrations. Growth inhibition and apoptosis, both linked to mTOR pathway activity, may explain these effects, as both YTXs were shown to downregulate this pathway. This proof-of-principle study supports the biogenics hypothesis, as specific aerosolizable marine products (e.g., YTXs) can downregulate the mTOR pathway.

The hidden biotechnological potential of marine invertebrates: The Polychaeta case study

Marine biotechnology is under the spotlight, as researchers and industrialists become aware that bioprospecting through the oceans' vast biodiversity can replace the painstaking process of designing synthetic compounds. Millions of years of Natural Selection provided an almost inexhaustible source of marine products that can interfere with specific bioprocesses while being cost-effective, safer and more environmentally friendly. Still, the number of commercial applications of marine compounds, especially from eumetazoans, can seem disappointing. In most part, this results from the challenges of dealing with an immense biodiversity and with poorly known organisms with uncanny physiology. Consequently, shifting the current perspective from descriptive science to actually proposing applications can be a major incentive to industry. With this in mind, the present review focuses on one of the least studied but most representative group of marine animals: the Polychaeta annelids. Occupying nearly every marine habitat, from the deep sea to the intertidal, they can offer a wide array of natural products that are just beginning to be understood, showing properties compatible with anaesthetics, fluorescent probes, and even antibiotics and pesticides, for instance. Altogether, they are a showcase for the ocean's real biotechnological deterrent, albeit our still wispy knowledge on this vast and ancient environment.