IgE and IgG4 epitopes of the peanut allergens shift following oral immunotherapy

Background Oral immunotherapy (OIT) with peanut (Arachis hypogaea) allergen powder-dnfp (PTAH; Aimmune Therapeutics) is an FDA-approved treatment to desensitize peanut allergic participants. Objective Here we assessed shifts in IgE and IgG4 binding to peanut allergens and their epitopes recognized by United States (US) peanut allergic participants (n = 20) enrolled in phase 3 PTAH OIT clinical trials. Methods Pre- and post- trial participant sera were collected approximately 12 months apart and tested for IgE binding to intact peanut proteins via ImmunoCAP ISAC immunoassays. IgE and IgG4 linear epitopes were identified based on binding to synthetic overlapping 15-mer linear peptides of 10 peanut allergens (Ara h 1-11) synthesized on microarray slides. Results Statistically significant decreases in IgE binding were identified for intact Ara h 2, 3, and 6, and known and newly identified IgE epitopes were shown to exhibit shifts towards IgG4 binding post-OIT, with most linear peptides having increased IgG4 binding after treatment with PTAH. While PTAH does not seem to alter the actual peptide binding patterns significantly after one year of treatment, the IgE and IgG4 binding ratios and intensity are altered. Conclusion At a population level, the linear IgE and IgG4 epitopes of 10 peanut allergens overlap and that increase in IgG4 with OIT results in displacement of IgE binding to both conformational and linear epitopes. Furthermore, it appears as though the increase in IgG4 is more important to achieve desensitization at the 12-month timepoint than the decrease in IgE. This type of knowledge can be useful in the identification of IgE and IgG4-binding allergen and peptide biomarkers that may indicate desensitization or sustained unresponsiveness of allergic individuals to peanut

Bacterial proliferation on clay nanotube Pickering emulsions for oil spill bioremediation

© 2018 Elsevier B.V. Halloysites (tubular aluminosilicate) are introduced as inexpensive natural nanoparticles that form and stabilize oil-water emulsions. Pickering emulsification can proceed with energies low enough to be afforded by ocean turbulence and the stability of droplets extends over more than a week. The oil/water interface is shown to be roughened and bacteria, which are added for oil degradation, are better attached to such oil droplets than to droplets without halloysites. The metabolic activity of Alcanivorax borkumensis, alkanotrophic bacteria widely distributed in marine environments, is enhanced by halloysite addition. A halloysite-based dispersant system is therefore environmentally friendly and promising for further optimization. The key elements of the described formulations are natural clay nanotubes, which are abundantly available in thousands of tons, thus making this technology scalable for environmental remediation

Biofilm Formation by Hydrocarbon-Degrading Marine Bacteria and Its Effects on Oil Dispersion

Biodegradation of oil by marine bacteria is a significant pathway to oil spill remediation. Marine hydrocarbon degrading bacteria are known to form biofilms consisting of exopolymer and interconnected bacterial cells. This work indicates that microbial biofilm aids in the stabilization of dispersed oil droplets through the formation of biofilm at the oil-water interface and is therefore an environmentally benign and sustainable method to aid dispersion of spilled oil. Using a model hydrocarbon degrading organism Alcanivorax borkumensis, we show, through a combination of optical and high-resolution cryogenic scanning electron microscopy, that these microbes sequester into biofilm at the oil-water interface. We show that the bacterial culture incubated for 3 days and containing biofilm can disperse oil slicks moderately well (40-50%) as estimated by the baffled flask test and can thus be used as an environmentally benign response to oil spills. The dispersion occurs through bacterial adsorption at the oil-water interface together with the aid of naturally secreted biosurfactants that lower the oil-water interfacial tension by a factor of 2 to around 23 mN/m. When the bacterial culture is incubated for a week, the presence of biofilm at the interface can have a hindering effect at oil dispersion through formation of a rigid interfacial layer of biofilm. We show that the dispersion effectiveness of the commercial dispersant Corexit 9500A decreased approximately 25% in the presence of a mature microbial biofilm at the interface. Hexadecane biodegradation by the microbial culture was estimated, and it was found that approximately 90% of hexadecane was degraded in the period of 5 days. This work provides a comprehensive view on marine microbial biofilm from a detailed characterization at the formation stage to the overall role in the context of oil spill dispersion and further biodegradation. Bacterial biofilm and biosurfactants represent fully environmentally sustainable and natural materials for oil spill dispersion

Engineered Clays as Sustainable Oil Dispersants in the Presence of Model Hydrocarbon Degrading Bacteria: The Role of Bacterial Sequestration and Biofilm Formation

Copyright © 2018 American Chemical Society. Particle stabilized emulsions provide an environmentally friendly alternative to the chemical dispersion of oil in the event of a spill over water. Mineral clay particles present in abundance in marine environments adsorb at oil-water interfaces forming stable emulsion droplets. We describe the carbonization of these clays using the sustainable biopolymer, chitosan, to optimize wetting characteristics and generate extremely stable 150 μm clay-armored droplets using a model crude (Anadarko). In addition to such droplet stabilization, the work is comprehensive in elucidating the microbial processes involved in oil biodegradation. Using a model alkane degrading organism Alcanivorax borkumensis acclimatized on n-hexadecane, the colonization of oil droplets and the growth of biofilm are clearly visualized through high-resolution cryo-scanning electron microscopy. The results indicate ubiquitous colonization of the organism on the surface and between platelets of the armored droplet with extensive biofilm formation bridging these particle stabilized droplets. Such oil-mineral aggregates stay buoyant, although excess clay particles embedded in biofilm sediment carry out small amounts of entrapped oil. Biodegradation is monitored through the loss of hexadecane doped into the crude oil, and it is found that 90% of the hexadecane is lost over a 6-day experiment. These findings provide a comprehensive description of oil dispersion by mineral clay particles in the presence of marine oil-degrading bacterium, with the potential of developing technology for the mitigation of the environmental impacts of oil spills

Investigation of Amphiphilic Polypeptoid-Functionalized Halloysite Nanotubes as Emulsion Stabilizer for Oil Spill Remediation

© 2019 American Chemical Society. Halloysite nanotubes (HNTs), naturally occurring and environmental benign clay nanoparticles, have been successfully functionalized with amphiphilic polypeptoid polymers by surface-initiated polymerization methods and investigated as emulsion stabilizers toward oil spill remediation. The hydrophilicity and lipophilicity balance (HLB) of the grafted polypeptoids was shown to affect the wettability of functionalized HNTs and their performance as stabilizers for oil-in-water emulsions. The functionalized HNTs having relatively high hydrophobic content (HLB = 12.0-15.0) afforded the most stable oil-in-water emulsions containing the smallest oil droplet sizes. This has been attributed to the augmented interfacial activities of polypeptoid-functionalized HNTs, resulting in more effective reduction of interfacial tension, enhancement of thermodynamic propensity of the HNT particles to partition at the oil-water interface, and increased emulsion viscosity relative to the pristine HNTs. Cell culture studies have revealed that polypeptoid-functionalized HNTs are noncytotoxic toward Alcanivorax borkumensis, a dominant alkane degrading bacterium found in the ocean after oil spill. Notably, the functionalized HNTs with higher hydrophobic polypeptoid content (HLB = 12.0-14.3) were shown to induce more cell proliferation than either pristine HNTs or those functionalized with less hydrophobic polypeptoids. It was postulated that the functionalized HNTs with higher hydrophobic polypeptoid content may promote the bacterial proliferation by providing larger oil-water interfacial area and better anchoring of bacteria at the interface