Biodiesel feedstock determines exhaust toxicity in 20% biodiesel: 80% mineral diesel blends

To address climate change concerns, and reduce the carbon footprint caused by fossil fuel use, it is likely that blend ratios of renewable biodiesel with commercial mineral diesel fuel will steadily increase, resulting in biodiesel use becoming more widespread. Exhaust toxicity of unblended biodiesels changes depending on feedstock type, however the effect of feedstock on blended fuels is less well known. The aim of this study was to assess the impact of biodiesel feedstock on exhaust toxicity of 20% blended biodiesel fuels (B20). Primary human airway epithelial cells were exposed to exhaust diluted 1/15 with air from an engine running on conventional ultra-low sulfur diesel (ULSD) or 20% blends of soy, canola, waste cooking oil (WCO), tallow, palm or cottonseed biodiesel in diesel. Physico-chemical exhaust properties were compared between fuels and the post-exposure effect of exhaust on cellular viability and media release was assessed 24 h later. Exhaust properties changed significantly between all fuels with cottonseed B20 being the most different to both ULSD and its respective unblended biodiesel. Exposure to palm B20 resulted in significantly decreased cellular viability (96.3 ± 1.7%; p < 0.01) whereas exposure to soy B20 generated the greatest number of changes in mediator release (including IL-6, IL-8 and TNF-α, p < 0.05) when compared to air exposed controls, with palm B20 and tallow B20 closely following. In contrast, canola B20 and WCO B20 were the least toxic with only mediators G-CSF and TNF-α being significantly increased. Therefore, exposure to palm B20, soy B20 and tallow B20 were found to be the most toxic and exposure to canola B20 and WCO B20 the least. The top three most toxic and the bottom three least toxic B20 fuels are consistent with their unblended counterparts, suggesting that feedstock type greatly impacts exhaust toxicity, even when biodiesel only comprises 20% of the fuel.

Toxicity of different biodiesel exhausts in primary human airway epithelial cells grown at air-liquid interface

Biodiesel is created through the transesterification of fats/oils and its usage is increasing worldwide as global warming concerns increase. Biodiesel fuel properties change depending on the feedstock used to create it. The aim of this study was to assess the different toxicological properties of biodiesel exhausts created from different feedstocks using a complex 3D air-liquid interface (ALI) model that mimics the human airway. Primary human airway epithelial cells were grown at ALI until full differentiation was achieved. Cells were then exposed to 1/20 diluted exhaust from an engine running on Diesel (ULSD), pure or 20% blended Canola biodiesel and pure or 20% blended Tallow biodiesel, or Air for control. Exhaust was analysed for various physio-chemical properties and 24-h after exposure, ALI cultures were assessed for permeability, protein release and mediator response. All measured exhaust components were within industry safety standards. ULSD contained the highest concentrations of various combustion gases. We found no differences in terms of particle characteristics for any of the tested exhausts, likely due to the high dilution used. Exposure to Tallow B100 and B20 induced increased permeability in the ALI culture and the greatest increase in mediator response in both the apical and basal compartments. In contrast, Canola B100 and B20 did not impact permeability and induced the smallest mediator response. All exhausts but Canola B20 induced increased protein release, indicating epithelial damage. Despite the concentrations of all exhausts used in this study meeting industry safety regulations, we found significant toxic effects. Tallow biodiesel was found to be the most toxic of the tested fuels and Canola the least, both for blended and pure biodiesel fuels. This suggests that the feedstock biodiesel is made from is crucial for the resulting health effects of exhaust exposure, even when not comprising the majority of fuel composition.

In Vitro primary human airway epithelial whole exhaust exposure

The method outlined in this article is a customization of the whole exhaust exposure method generated by Mullins et al. (2016) using reprogrammed primary human airway epithelial cells as described by Martinovich et al. (2017). It has been used successfully to generate recently published data (Landwehr et al. 2021). The goal was to generate an exhaust exposure model where exhaust is collected from a modern engine, real-world exhaust concentrations are used and relevant tissues exposed to assess the effects of multiple biodiesel exposures. Exhaust was generated, gently vacuumed into a dilution chamber where it was diluted 1/15 with air and then vacuumed into an incubator containing the primary cell cultures for exposure. Exhaust physico-chemical properties including combustion gas concentrations and particle spectra were then analyzed using a combustion gas analyzer and a Universal Scanning Mobility Particle Sizer. 24 h after exposure, cellular viability and mediator release were measured using Annexin-V/PI staining and meditator multiplexing kits respectively. This method was generated to test biodiesel exhaust exposures but can be easily adapted for any type of engine exhaust exposure or even potentially other respirable environmental exposures such as woodsmoke.

The main customization points for this method are:•

Exhaust generated by a diesel engine equipped with EURO VI exhaust after treatment devices including diesel particulate filter and diesel oxidation catalyst.

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The generated exhaust was diluted 1/15 with air to replicate real world exposure concentrations.

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Used primary human airway epithelial cells obtained from bronchoscope brushings from multiple volunteers and reprogrammed to allow multiple, comparative exposures from the same individual.

Fuel feedstock determines biodiesel exhaust toxicity in a human airway epithelial cell exposure model

BACKGROUND

Biodiesel is promoted as a sustainable replacement for commercial diesel. Biodiesel fuel and exhaust properties change depending on the base feedstock oil/fat used during creation. The aims of this study were, for the first time, to compare the exhaust exposure health impacts of a wide range of biodiesels made from different feedstocks and relate these effects with the corresponding exhaust characteristics.

METHOD

Primary airway epithelial cells were exposed to diluted exhaust from an engine running on conventional diesel and biodiesel made from Soy, Canola, Waste Cooking Oil, Tallow, Palm and Cottonseed. Exhaust properties and cellular viability and mediator release were analysed post exposure.

RESULTS

The exhaust physico-chemistry of Tallow biodiesel was the most different to diesel as well as the most toxic, with exposure resulting in significantly decreased cellular viability (95.8 ± 6.5%) and increased release of several immune mediators including IL-6 (+223.11 ± 368.83 pg/mL) and IL-8 (+1516.17 ± 2908.79 pg/mL) above Air controls. In contrast Canola biodiesel was the least toxic with exposure only increasing TNF-α (4.91 ± 8.61).

CONCLUSION

This study, which investigated the toxic effects for the largest range of biodiesels, shows that exposure to different exhausts results in a spectrum of toxic effects in vitro when combusted under identical conditions.

Development and validation of a miniaturized bacteriophage host range screening assay against antibiotic resistant Pseudomonas aeruginosa

Antimicrobial resistance is a current global health crisis, and the increasing emergence of multidrug resistant infections has led to the resurgent interest in bacteriophages as an alternative treatment. Prior to clinical application, phage suitability is assessed, via susceptibility testing and breadth of host range to bacteriophage, however, these are both large-scale manual processes and labor-intensive. The aim of the study was to establish and validate a scaled down methodology for high-throughput screening to reduce procedural footprint. In this paper, we describe a scaled-down adapted methodology that can successfully screen bacteriophages, isolated and purified from wastewater samples. Furthermore, we describe a miniaturized host range assay against clinical Pseudomonas aeruginosa isolates using a spot test (2 μL/ drop) that was found to be both sensitive (94.6%) and specific (94.7%). It also demonstrated a positive predictive value (PPV) of 86.4% and negative predictive value (NPV) of 98%. The breadth of host range of bacteriophages that exhibited lytic activity on P. aeruginosa isolates was corroborated using the scaled down assay. The high correlation achieved in this study confirms miniaturization as the first step in future automation that could test phage diversity and efficacy as antimicrobials.

Nasal airway epithelial repair after very preterm birth

Preterm birth rates are increasing and now account for >11% of global births. Simultaneously, advances in neonatal care have led to increased survival of lower gestation neonates. A complication of preterm birth, and the biggest determinant of survival, is lung and airway immaturity. After preterm birth, the immature respiratory system is exposed to pro-inflammatory stimuli like injury from resuscitation and oxygen toxicity. The airway epithelium, the physical barrier between insults and the airways, is particularly vulnerable to injury. If epithelial barrier integrity cannot be restored rapidly following damage (i.e. via aberrant repair), the respiratory system is left unprotected, increasing the risk of infection, inflammation and tissue damage. Altered epithelial repair may play an important role in the ongoing respiratory health problems experienced by preterm survivors, including severe respiratory infections throughout early life, or low and declining lung function [1–3]. Deficits are further exacerbated in those with bronchopulmonary dysplasia (BPD). The mechanisms contributing to ongoing respiratory problems are currently unknown, although probably begin in early life. Until now, understanding the role of the preterm epithelial barrier has been limited by a lack of appropriate cellular models. Our study aimed to assess the reparative capacity of the airway epithelium in survivors of preterm birth and its association with early life outcomes, with the hypothesis that preterm airway epithelial cells have an abnormal repair mechanism.

Nasal epithelialcells from very preterm infants have a functional defect in their ability to repair beyond the first year of life, and failed repair may be associated with antenatal steroid exposurehttps://bit.ly/39OFJs7

Ivacaftor or lumacaftor/ivacaftor treatment does not alter the core CF airway epithelial gene response to rhinovirus

BACKGROUND

Aberrant responses by the cystic fibrosis airway epithelium during viral infection may underly the clinical observations. Whether CFTR modulators affect antiviral responses by CF epithelia is presently unknown. We tested the hypothesis that treatment of CF epithelial cells with ivacaftor (Iva) or ivacaftor/lumacaftor (Iva/Lum) would improve control of rhinovirus infection.

METHODS

Nineteen CF epithelial cultures (10 homozygous for p.Phe508del as CFTR Class 2, 9 p.Phe508del/p.Gly551Asp as Class 3) were infected with rhinovirus 1B at multiplicity of infection 12 for 24 h. Culture RNA and supernatants were harvested to assess gene and protein expression respectively.

RESULTS

RNA-seq analysis comparing rhinovirus infected cultures to control identified 796 and 629 differentially expressed genes for Class 2 and Class 3, respectively. This gene response was highly conserved when cells were treated with CFTR modulators and were predicted to be driven by the same interferon-pathway transcriptional regulators (IFNA, IFNL1, IFNG, IRF7, STAT1). Direct comparisons between treated and untreated infected cultures did not yield any differentially expressed genes for Class 3 and only 68 genes for Class 2. Changes were predominantly related to regulators of lipid metabolism and inflammation, aspects of epithelial biology known to be dysregulated in CF. In addition, CFTR modulators did not affect viral copy number, or levels of pro-inflammatory cytokines produced post-infection.

CONCLUSIONS

Though long-term clinical data is not yet available, results presented here suggest that first generation CFTR modulators do not interfere with core airway epithelial responses to rhinovirus infection. Future work should investigate the latest triple modulation therapies.

Aberrant cell migration contributes to defective airway epithelial repair in childhood wheeze

Abnormal wound repair has been observed in the airway epithelium of patients with chronic respiratory diseases, including asthma. Therapies focusing on repairing vulnerable airways, particularly in early life, present a potentially novel treatment strategy. We report defective lower airway epithelial cell repair to strongly associate with common pre-school-aged and school-aged wheezing phenotypes, characterized by aberrant migration patterns and reduced integrin α5β1 expression. Next generation sequencing identified the PI3K/Akt pathway as the top upstream transcriptional regulator of integrin α5β1, where Akt activation enhanced repair and integrin α5β1 expression in primary cultures from children with wheeze. Conversely, inhibition of PI3K/Akt signaling in primary cultures from children without wheeze reduced α5β1 expression and attenuated repair. Importantly, the FDA-approved drug celecoxib - and its non-COX2-inhibiting analogue, dimethyl-celecoxib - stimulated the PI3K/Akt-integrin α5β1 axis and restored airway epithelial repair in cells from children with wheeze. When compared with published clinical data sets, the identified transcriptomic signature was also associated with viral-induced wheeze exacerbations highlighting the clinical potential of such therapy. Collectively, these results identify airway epithelial restitution via targeting the PI3K-integrin α5β1 axis as a potentially novel therapeutic avenue for childhood wheeze and asthma. We propose that the next step in the therapeutic development process should be a proof-of-concept clinical trial, since relevant animal models to test the crucial underlying premise are unavailable.

Soy Biodiesel Exhaust is More Toxic than Mineral Diesel Exhaust in Primary Human Airway Epithelial Cells

As global biodiesel production increases, there are concerns over the potential health impact of exposure to the exhaust, particularly in regard to young children who are at high risk because of their continuing lung development. Using human airway epithelial cells obtained from young children, we compared the effects of exposure to exhaust generated by a diesel engine with Euro V/VI emission controls running on conventional diesel (ultra-low-sulfur mineral diesel, ULSD), soy biodiesel (B100), or a 20% blend of soy biodiesel with diesel (B20). The exhaust output of biodiesel was found to contain significantly more respiratory irritants, including NO_x, CO, and CO₂, and a larger overall particle mass. Exposure to biodiesel exhaust resulted in significantly greater cell death and a greater release of immune mediators compared to both air controls and ULSD exhaust. These results have concerning implications for potential global health impacts, particularly for the pediatric population.

Azithromycin reduces airway inflammation induced by human rhinovirus in lung allograft recipients

BACKGROUND AND OBJECTIVE

Human rhinovirus (RV) is a common upper and lower respiratory pathogen in lung allograft recipients causing respiratory tract exacerbation and contributing towards allograft dysfunction and long-term lung decline. In this study, we tested the hypothesis that RV could infect both the small and large airways, resulting in significant inflammation.

METHODS

Matched large and small airway epithelial cells (AEC) were obtained from five lung allograft recipients. Primary cultures were established, and monolayers were infected with RV1b over time with varying viral titre. Cell viability, receptor expression, viral copy number, apoptotic induction and inflammatory cytokine production were also assessed at each region. Finally, the effect of azithromycin on viral replication, induction of apoptosis and inflammation was investigated.

RESULTS

RV infection caused significant cytotoxicity in both large AEC (LAEC) and small AEC (SAEC), and induced a similar apoptotic response in both regions. There was a significant increase in receptor expression in the LAEC only post viral infection. Viral replication was elevated in both LAEC and SAEC, but was not significantly different. Prophylactic treatment of azithromycin reduced viral replication and dampened the production of inflammatory cytokines post-infection.

CONCLUSION

Our data illustrate that RV infection is capable of infecting upper and lower AEC, driving cell death and inflammation. Prophylactic treatment with azithromycin was found to mitigate some of the detrimental responses. Findings provide further support for the prophylactic prescription of azithromycin to minimize the impact of RV infection.

Allergic sensitivity confirmed by the release of histamine from small blood samples

An enzymatic-isotopic microassay that can measure picogram amounts of histamine in 20 microliter samples of plasma has been used to confirm diagnosis of allergic sensitivity to extracts of house dust mite, cat dander, grass, plantain, Cladosporium mould and bee sting venom by the skin test procedure. Multiple assays for allergic histamine release can be performed on minimal blood samples resulting in a qualitative and quantitative prediction of allergic sensitivity from an in vitro biochemical procedure.

A comparative trial of intra-nasal beclomethasone dipropionate and sodium cromoglycate in patients with chronic perennial rhinitis

A double-blind crossover study has compared intra-nasal sodium cromoglycate (SCG) with beclomethasone dipropionate (BDP), and both drugs with placebo, in fifty-two chronic perennial rhinitis patients. BDP was significantly more effective in relieving symptoms than SCG (76.9% and 50% of the patients improved respectively, P < 0.01). Both drugs were more active than placebos but while BDP was very clearly more effective (P < 0.0005) SCG was only marginally better than its placebo (P < 0.05, Fisher; P = 0.068, chi 2). BDP was selected by 56% of the patients as the best agent for continuing therapy at the end of the trial. By contrast SCG was preferred by the same number of patients as chose the two placebos (11.5%).