Is the epithelial barrier hypothesis the key to understanding the higher incidence and excess mortality during COVID-19 pandemic? The case of Northern Italy.

The high incidence and increased mortality of COVID-19 make Italy among the most impacted countries by SARS-CoV-2 outbreak. In the beginning of the pandemic, Northern regions accounted for 40% of cases and 45% of deaths from COVID-19 in Italy. Several factors have been suggested to explain the higher incidence and excess mortality from COVID-19 in these regions. It is noticed that Northern Italian regions, and particularly the cities in Po Valley, are the areas with the highest air pollution due to commercial vehicle traffic, industry and a stagnant meteorological condition, with one of the highest levels in Italy and Europe of fine particulate matter 2.5 micron or smaller in size (PM2.5). PM2.5, the major environmental pollutant deriving mainly by factory and automobile exhaust emissions and coal combustion, increases the expression of angiotensin-converting enzyme 2, the epithelial cell entry receptor for SARS-CoV-2, and thus increase the susceptibility to this virus. The epithelial barrier hypothesis proposes that many diverse diseases may rise from the disruption of epithelial barrier of skin, respiratory tract and gastrointestinal system, including allergic diseases, metabolic and autoimmune diseases, and chronic neuropsychiatric conditions. There is evidence of a close correlation between air pollution and airway epithelial barrier dysfunction. Air pollution, causing lung epithelial barrier dysfunction, may contribute to local chronic inflammation, microbiome dysbiosis and impaired antiviral immune response against SARS-CoV-2, all of which contribute to the high incidence and excess mortality from COVID-19. In addition, air pollution and epithelial barrier dysfunction contribute also to the higher prevalence of several comorbidities of COVID-19, such as diabetes, chronic obstructive pulmonary disease and obesity, which have been identified as risk factors for mortality of COVID-19. In this article, on the basis of epidemiological and environmental monitoring data in Northern Italy, it is suggested that epithelial barrier hypothesis may help to understand the excess burden and mortality from COVID-19.

Distribution in the brain and possible neuroprotective effects of intranasally delivered multi-walled carbon nanotubes.

Carbon nanotubes (CNTs) are currently under active investigation for their use in several biomedical applications, especially in neurological diseases and nervous system injury due to their electrochemical properties. Nowadays, no CNT-based therapeutic products for internal use appear to be close to the market, due to the still limited knowledge on their fate after delivery to living organisms and, in particular, on their toxicological profile. The purpose of the present work was to address the distribution in the brain parenchyma of two intranasally delivered MWCNTs (MWCNTs 1 and a-MWCNTs 2), different from each other, the first being non electroconductive while the second results in being electroconductive. After intranasal delivery, the presence of CNTs was investigated in several brain areas, discriminating the specific cell types involved in the CNT uptake. We also aimed to verify the neuroprotective potential of the two types of CNTs, delivering them in rats affected by early diabetic encephalopathy and analysing the modulation of nerve growth factor metabolism and the effects of CNTs on the neuronal and glial phenotypes. Our findings showed that both CNT types, when intranasally delivered, reached numerous brain areas and, in particular, the limbic area that plays a crucial role in the development and progression of major neurodegenerative diseases. Furthermore, we demonstrated that electroconductive MWCNTs were able to exert neuroprotective effects through the modulation of a key neurotrophic factor and probably the improvement of neurodegeneration-related gliosis.

Association Between Metabolic and Hormonal Derangements and Professional Exposure to Urban Pollution in a High Intensity Traffic Area.

Rationale: Studies suggest a relation between exposure to air particulate matter (PM)2.5 pollution and greater cardiovascular morbidity, as well as increased risk for obesity and diabetes. We aimed to identify association(s) between nutritional and metabolic status and exposure to environmental pollution in a cohort of policemen exposed to high levels of air pollution. Methods: We considered adult municipal policemen, working in an urban area at high-traffic density with documented high levels of air PM2.5 (exposed group) compared to non-exposed policemen. Clinical characteristics, including the presence/absence of metabolic syndrome, were recorded, and serum biomarkers, including adiponectin, leptin, and ghrelin, were assessed. Results: One hundred ninety-nine participants were enrolled, 100 in the exposed group and 99 in the non-exposed group. Metabolic syndrome was documented in 32% of exposed group and in 52.5% of non-exposed group (P = 0.008). In the exposed group, we found a positive correlation between body mass index and serum leptin as well as in the non-exposed group (P < 0.0001). Within the exposed group, subjects with metabolic syndrome showed lower serum adiponectin (P < 0.0001) and higher leptin (P = 0.002) levels with respect to those without metabolic syndrome, whereas in the non-exposed group, subjects with metabolic syndrome showed only higher leptin levels when compared to those without metabolic syndrome (P = 0.01). Among the participants with metabolic syndrome, we found lower adiponectin levels in those of the exposed group with respect to the non-exposed ones (P = 0.007). When comparing the exposed and non-exposed groups, after stratifying participants for Homeostatic Model Assessment for Insulin Resistance >2.5, we found lower adiponectin levels in those of the exposed group with respect to the non-exposed ones (P = 0.038). Conclusions: Exposure to air PM pollution was associated with lower levels of adiponectin in adult males with metabolic syndrome.

Diesel exhaust particles induce autophagy and citrullination in Normal Human Bronchial Epithelial cells.

A variety of environmental agents has been found to influence the development of autoimmune diseases; in particular, the studies investigating the potential association of systemic autoimmune rheumatic diseases with environmental micro and nano-particulate matter are very few and contradictory. In this study, the role of diesel exhaust particles (DEPs), one of the most important components of environment particulate matter, emitted from Euro 4 and Euro 5 engines in altering the Normal Human Bronchial Epithelial (NHBE) cell biological activity was evaluated. NHBE cells were exposed in vitro to Euro 4 and Euro 5 particle carbon core, sampled upstream of the typical emission after-treatment systems (diesel oxidation catalyst and diesel particulate filter), whose surfaces have been washed from well-assessed harmful species, as polycyclic aromatic hydrocarbons (PAHs) to: (1) investigate their specific capacity to affect cell viability (flow cytometry); (2) stimulate the production of the pro-inflammatory cytokine IL-18 (Enzyme-Linked ImmunoSorbent Assay -ELISA-); (3) verify their specific ability to induce autophagy and elicit protein citrullination and peptidyl arginine deiminase (PAD) activity (confocal laser scanning microscopy, immunoprecipitation, Sodium Dodecyl Sulphate-PolyAcrylamide Gel Electrophoresis -SDS-PAGE- and Western blot, ELISA). In this study we demonstrated, for the first time, that both Euro 4 and Euro 5 carbon particles, deprived of PAHs possibly adsorbed on the soot surface, were able to: (1) significantly affect cell viability, inducing autophagy, apoptosis and necrosis; (2) stimulate the release of the pro-inflammatory cytokine IL-18; (3) elicit protein citrullination and PAD activity in NHBE cells. In particular, Euro 5 DEPs seem to have a more marked effect with respect to Euro 4 DEPs.

Supplementing π-systems: eumelanin and graphene-like integration towards highly conductive materials for the mammalian cell culture bio-interface.

Organic (bio)electronics appears to be the first target for competitive exploitation in the materials science of eumelanins, black insoluble photoprotective human biopolymers. Nonetheless, the low conductivity of these pigments is limiting the implementation of eumelanin-based devices. Here we present a novel organic/organic hybrid material (EUGL) by integration of conductive graphene-like (GL) layers within the EUmelanin pigment (EU). GL layers were obtained by a two-step oxidation/reduction of carbon black. The stability of GL layers over a wide pH range and the self-assembling tendency place this material in a leading position for the fabrication of hybrid materials in aqueous media. EUGL was obtained by inducing the polymerization of eumelanin precursors (5,6-dihydroxyindole, DHI and 5,6-dihydroxyindole-2 carboxylic acid, DHICA) in aqueous media containing GL layers. The new material featured promising biocompatibility and an increased conductivity with respect to eumelanin by four orders of magnitude.

Diesel exhaust particle exposure in vitro impacts T lymphocyte phenotype and function.

BACKGROUND: Diesel exhaust particles (DEP) are major constituents of ambient air pollution and their adverse health effect is an area of intensive investigations. With respect to the immune system, DEP have attracted significant research attention as a factor that could influence allergic diseases interfering with cytokine production and chemokine expression. With this exception, scant data are available on the impact of DEP on lymphocyte homeostasis. Here, the effects of nanoparticles from Euro 4 (E4) and Euro 5 (E5) light duty diesel engines on the phenotype and function of T lymphocytes from healthy donors were evaluated. METHODS: T lymphocytes were isolated from peripheral blood obtained from healthy volunteers and subsequently stimulated with different concentration (from 0.15 to 60 µg/ml) and at different time points (from 24 h to 9 days) of either E4 or E5 particles. Immunological parameters, including apoptosis, autophagy, proliferation levels, mitochondrial function, expression of activation markers and cytokine production were evaluated by cellular and molecular analyses. RESULTS: DEP exposure caused a pronounced autophagic-lysosomal blockade, thus interfering with a key mechanism involved in the maintaining of T cell homeostasis. Moreover, DEP decreased mitochondrial membrane potential but, unexpectedly, this effect did not result in changes of the apoptosis and/or necrosis levels, as well as of intracellular content of adenosine triphosphate (ATP). Finally, a down-regulation of the expression of the alpha chain of the interleukin (IL)-2 receptor (i.e., the CD25 molecule) as well as an abnormal Th1 cytokine expression profile (i.e., a decrease of IL-2 and interferon (IFN)-γ production) were observed after DEP exposure. No differences between the two compounds were detected in all studied parameters. CONCLUSIONS: Overall, our data identify functional and phenotypic T lymphocyte parameters as relevant targets for DEP cytotoxicity, whose impairment could be detrimental, at least in the long run, for human health, favouring the development or the progression of diseases such as autoimmunity and cancer.

Inhibition of microbial growth by carbon nanotube networks.

In the last years carbon nanotubes have attracted increasing attention for their potential applications in the biomedical field as diagnostic and therapeutic nano tools. Here we investigate the antimicrobial activity of different fully characterized carbon nanotube types (single walled, double walled and multi walled) on representative pathogen species: Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and the opportunistic fungus Candida albicans. Our results show that all the carbon nanotube types possess a highly significant antimicrobial capacity, even though they have a colony forming unit capacity and induction of oxidative stress in all the microbial species to a different extent. Moreover, scanning electron microscopy analysis revealed that the microbial cells were wrapped or entrapped by carbon nanotube networks. Our data taken together suggest that the reduced capacity of microbial cells to forming colonies and their oxidative response could be related to the cellular stress induced by the interactions of pathogens with the CNT network.

Highly electroconductive multiwalled carbon nanotubes as potentially useful tools for modulating calcium balancing in biological environments.

Aiming to explore the mechanisms modulating cell-carbon nanotube interactions, we investigated whether Ca(2+) ion balancing between intra- and extracellular environments could be affected by multiwalled carbon nanotubes (MWCNTs). We analyzed the effects induced by two different kinds of MWCNTs (as prepared and annealed at 2400°C) on the intracellular Ca(2+) ion levels in rat electrically sensitive cells and on the intercellular junction integrity of rat adenocarcinoma colon cells and platelet aggregation ability, which depend on the Ca(2+) concentration in the medium. MWCNTs, purified by annealing and more electroconductive as compared to nonannealed MWCNTs, affected Ca(2+) ion balancing between extra- and intracellular environments and induced changes on Ca(2+) ion-dependent cellular junctions and platelet aggregation, behaving as the calcium chelator ethylene glycol tetraacetic acid. This could be due to the sorption of cationic Ca(2+) ions on CNTs surface because of the excess of negatively charged electrons on the aromatic units formed on MWCNTs after annealing. From the ClinicAL Editor: The authors investigated whether Ca(2+) ion balance between intra- and extracellular space can be modulated by multiwalled carbon nanotubes (MWCNTs). Annealed nanotubes induced changes on Ca(2+) dependent cellular junctions and platelet aggregation, behaving similary to ethylene glycol tetraacetic acid, an established calcium chelator.

Cytotoxicity and inflammatory potential of soot particles of low-emission diesel engines.

We evaluated, in vitro, the inflammatory and cytotoxic potential of soot particles from current low-emission (Euro IV) diesel engines toward human peripheral blood monocyte-derived macrophage cells. The result is surprising. At the same mass concentration, soot particles produced under low-emission conditions exhibit a much highertoxic and inflammatory potential than particles from an old diesel engine operating under black smoke conditions. This effect is assigned to the defective surface structure of Euro IV diesel soot, rendering it highly active. Our findings indicate that the reduction of soot emission in terms of mass does not automatically lead to a reduction of the toxic effects toward humans when the structure and functionality of the soot is changed, and thereby the biological accessibility and inflammatory potential of soot is increased.

Nanosurfaces and nanostructures for artificial orthopedic implants.

Nanomaterials and structures, such as nanoparticles, nanofibers, nanosurfaces, nanocoatings, nanoscaffolds and nanocomposites, are considered for various applications in orthopedics and traumatology. This review looks at proposed nanotechnology inspired applications for implants from the perspective of the orthopedic industry. Investigations support consistently the theory that most nanomaterials in various physical forms are able to enhance the cell response selectively for biological tissue integration or increase the strength and wear resistance of current orthopedic materials. At this stage, most of the studies are at the laboratory scale or in early in vivo testing. Significant basic and applied research and development is needed to realize their full clinical potential and biological, manufacturing, economic and regulatory issues have to be addressed. Nevertheless, a crucial factor for success is well-coordinated multimethod and multidiscipline teamwork with profound industrial and medical expertise.

Biocompatibility and applications of carbon nanotubes in medical nanorobots.

The set of nanoelectromechanical systems (NEMS) based on relative motion of carbon nanotubes walls is proposed for use in medical nanorobots. This set includes electromechanical nanothermometer, jet nanoengine, nanosyringe (the last can be used simultaneously as nanoprobe for individual biological molecules and drug nanodeliver). Principal schemes of these NEMS are considered. Operational characteristics of nanothermometer are analyzed. The possible methods of these NEMS actuation are considered. The present-day progress in nanotechnology techniques which are necessary for assembling of NEMS under consideration is discussed. Biocompatibility of carbon nanotubes is analyzed in connection with perspectives of their application in nanomedicine.