Human γδ T cell Recognition of lipid A is predominately presented by CD1b or CD1c on dendritic cells

<p>Abstract</p> <p>Background</p> <p>The γδ T cells serve as early immune defense against certain encountered microbes. Only a few γδ T cell-recognized ligands from microbial antigens have been identified so far and the mechanisms by which γδ T cells recognize these ligands remain unknown. Here we explored the mechanism of interaction of human γδ T cells in peripheral blood with Lipid A (LA).</p> <p>Results</p> <p>First, resting γδ T cells (mainly Vδ2 T cells) displayed a strong proliferative response to LA-pulsed monocyte-derived dendritic cells (moDC) and LA-pulsed paraformaldehyde-fixed moDC, but not to free LA in a TCR γδ-dependent manner. Second, anti-CD1b or anti-CD1c antibodies could block proliferative response of resting γδ T cells to LA-loaded moDC. Besides, only LA-loaded CD1b/CD1c-transfected C1R lymphoblastoma cells (CD1b-/CD1c-C1R) were able to stimulate the proliferation of human γδ T cells. Third, the expressions of both Toll-like receptor (TLR)2 and TLR4 on surface of LA-activated γδ T cells were upregulated, whereas only anti-TLR4 antibody could partially block their response to LA; Finally LA-loaded moDCs induce γδ T cells to produce Th1 cytokines, such as IFN-γ.</p> <p>Conclusion</p> <p>Taken together, we found a novel mechanism that human γδ T cells recognize LA in a CD1b- or CD1c-restricted manner in first response against Gram-bacteria, while the interaction between TLR4 on γδ T cells and LA might strengthen the subsequent response of γδ T cells.</p> <p>Reviewers</p> <p>This article was reviewed by Hao Shen, Youwen He (nominated by Dr. Laurence C Eisenlohr), Dr. Michael Lenardo and Dr. Pushpa Pandiyan.</p

Effects of hydrodynamic cavitation on physicochemical structure and emulsifying properties of tilapia (Oreochromis niloticus) myofibrillar protein

The purpose of this research was to explore the different hydrodynamic cavitation (HC) times (0, 5, 10, 15, 20 min; power 550 W, pressure 0.14 MPa) on the emulsifying properties of tilapia myofibrillar protein (TMP). Results of pH, particle size, turbidity, solubility, surface hydrophobicity, and reactive sulfhydryl (SH) group indicated that HC changed the structure of TMP, as confirmed by the findings of intrinsic fluorescence and circular dichroism (CD) spectra. Furthermore, HC increased the emulsifying activity index (EAI) significantly (P &lt; 0.05) and changed the emulsifying stability index (ESI), droplet size, and rheology of TMP emulsions. Notably, compared with control group, the 10-min HC significantly decreased particle size and turbidity but increased solubility (P &lt; 0.05), resulting in accelerated diffusion of TMP in the emulsion. The prepared TMP emulsion showed the highest ESI (from 71.28 ± 5.50 to 91.73 ± 5.56 min), the smallest droplet size (from 2,754 ± 110 to 2,138 ± 182 nm) and the best rheological properties, as demonstrated by the microstructure photographs. Overall, by showing the effect of HC in improving the emulsifying properties of TMP, the study demonstrated HC as a potential technique for meat protein processing

Influence of photochemical loss of volatile organic compounds on understanding ozone formation mechanism

Volatile organic compounds (VOCs) tend to be consumed by atmospheric oxidants, resulting in substantial photochemical loss during transport. An observation-based model was used to evaluate the influence of photochemical loss of VOCs on the sensitivity regime and mechanisms of ozone formation. Our results showed that a VOC-limited regime based on observed VOC concentrations shifted to a transition regime with a photochemical initial concentration of VOCs (PIC-VOCs) in the morning. The net ozone formation rate was underestimated by 3 ppbh(-1) (similar to 36 ppb d(-1)) based on the measured VOCs when compared with the PIC-VOCs. The relative contribution of the RO2 path to ozone production based on the PIC-VOCs accordingly increased by 13.4 %; in particular, the contribution of alkene-derived RO(2 )increased by approximately 10.2 %. In addition, the OH-HO2 radical cycle was obviously accelerated by highly reactive alkenes after accounting for photochemical loss of VOCs. The contribution of local photochemistry might be underestimated for both local and regional ozone pollution if consumed VOCs are not accounted for, and policymaking on ozone pollution prevention should focus on VOCs with a high reactivity.Peer reviewe

Precursor apportionment of atmospheric oxygenated organic molecules using a machine learning method

Publisher Copyright: © 2023 The Author(s). Published by the Royal Society of Chemistry.Gas-phase oxygenated organic molecules (OOMs) can contribute significantly to both atmospheric new particle growth and secondary organic aerosol formation. Precursor apportionment of atmospheric OOMs connects them with volatile organic compounds (VOCs). Since atmospheric OOMs are often highly functionalized products of multistep reactions, it is challenging to reveal the complete mapping relationships between OOMs and their precursors. In this study, we demonstrate that the machine learning method is useful in attributing atmospheric OOMs to their precursors using several chemical indicators, such as O/C ratio and H/C ratio. The model is trained and tested using data acquired in controlled laboratory experiments, covering the oxidation products of four main types of VOCs (isoprene, monoterpenes, aliphatics, and aromatics). Then, the model is used for analyzing atmospheric OOMs measured in both urban Beijing and a boreal forest environment in southern Finland. The results suggest that atmospheric OOMs in these two environments can be reasonably assigned to their precursors. Beijing is an anthropogenic VOC dominated environment with ~64% aromatic and aliphatic OOMs, and the other boreal forested area has ~76% monoterpene OOMs. This pilot study shows that machine learning can be a promising tool in atmospheric chemistry for connecting the dots.Peer reviewe

Dust emission reduction enhanced gas-to-particle conversion of ammonia in the North China Plain

Liu et al. found that the formation rate of particulate ammonium is slower in the atmosphere than that observed in the laboratory, while it is sped up due to an increase in aerosol acidity driven by an emission reduction of dust in North China Plain.Ammonium salt is an important component of particulate matter with aerodynamic diameter less than 2.5 mu m (PM2.5) and has significant impacts on air quality, climate, and natural ecosystems. However, a fundamental understanding of the conversion kinetics from ammonia to ammonium in unique environments of high aerosol loading is lacking. Here, we report the uptake coefficient of ammonia (gamma(NH3)) on ambient PM2.5 varying from 2.2 x 10(-4) to 6.0 x 10(-4) in the North China Plain. It is significantly lower than those on the model particles under simple conditions reported in the literature. The probability-weighted gamma(NH3) increases obviously, which is well explained by the annual decrease in aerosol pH due to the significant decline in alkali and alkali earth metal contents from the emission source of dust. Our results elaborate on the complex interactions between primary emissions and the secondary formation of aerosols and the important role of dust in atmospheric chemistry.Peer reviewe