Metformin, an anti‐diabetic drug, possesses anti‐inflammatory property beyond its glucose‐lowering activity, but its regulatory effect on mast cells and allergic responses remains unknown, wherein ...the aryl hydrocarbon receptor (AhR)‐ligand axis is critical in controlling mast cell activation. Herein, we provide evidence supporting the role of metformin in modulating mast cell activation by FcεR1‐, AhR‐mediated signaling or their combination. Metformin at relatively low doses was shown to suppress FcεR1‐mediated degranulation, IL‐13, TNF‐α and sphingosine‐1‐phosphate (S1P) secretion in murine bone marrow‐derived mast cells (BMMCs). In contrast, metformin at the same doses potently inhibited all parameters in mast cells stimulated with an AhR ligand, 5,11‐dihydroindolo3,2‐bcarbazole‐6‐carbaldehyde (FICZ). Further, metformin was shown to inhibit FcεR1‐ and AhR‐mediated passive cutaneous anaphylaxis (PCA) in vivo, reversible by a S1P receptor 2 antagonist, JTE‐013. Using AhR reporter cells, Huh7‐DRE‐Luc cells, a human mast cell line, HMC‐1, and BMMCs, metformin's inhibitory effect was mediated through the suppression of FICZ‐induced AhR activity, calcium mobilization and ROS generation. Notably, FICZ‐mediated oxidation of S1P lyase (S1PL) and its reduced activity were reversed by metformin, resulting in decreased levels of S1P. Collectively, these results suggested the potential utility of metformin in treating allergic diseases, particularly in cases with comorbid type II diabetes mellitus.
A model for Metformin (Met)‐mediated suppression of aryl hydrocarbon receptor (AhR)‐ and IgE‐induced mast cell response via inhibiting (1) AhR's activity, (2) oxidative stress (ROS), resulting in reduced levels of calcium mobilization and oxidized S1PL (S1P lyase, a S1P degrading enzyme) and hence decreased S1P, and suppressing (3) IgE‐mediated signaling.
Club cells are critical in maintaining airway integrity via, in part, secretion of immunomodulatory Club cell 10 kd protein (CC10) and xenobiotic detoxification. Aryl hydrocarbon receptor (AhR) is ...important in xenobiotic metabolism, but its role in Club cell function is unclear. To this end, an AhR ligand, 6-formylindolo3,2-bcarbazole (FICZ, 10 nM) was found to induce, in a ligand and AhR-dependent manner, endoplasmic reticulum stress, phospholipid remodeling, free fatty acid and triglyceride synthesis, leading to perilipin 2-dependent lipid droplet (LD) biogenesis in a Club cell-like cell line, NL20. The increase in LDs was due, in part, to the blockade of adipose triglyceride lipase to LDs, while perilipin 5 facilitated LDs-mitochondria connection, leading to the breakdown of LDs via mitochondrial β-oxidation and acetyl-coA generation. In FICZ-treated cells, increased CC10 secretion and its intracellular association with LDs were noted. Administration of low (0.28 ng), medium (1.42 ng), and high (7.10 ng) doses of FICZ in C57BL/6 mice significantly enhanced lipopolysaccharide (LPS, 0.1 μg)-induced airway inflammation, mucin secretion, pro-inflammatory cytokines and CC10 in the bronchoalveolar lavage fluids, as compared to those seen in mice receiving LPS alone, suggesting the importance of AhR signaling in controlling the metabolic homeostasis and functions of Club cells.
•Colorimetric method using gold nanoparticles in a micro-concentrator.•Using ion concentration polarization near an ion-selective membrane to concentrate.•Acquiring the concentrated spots of gold ...nanoparticles with phone camera.•Validated urine protein determination using color intensity of concentration spot.
In this paper, we use an ion-exchange membrane disk to develop miniaturized concentration device, which employs gold nanoparticle (GNP) colorimetric assay to determine human serum albumin content in artificial urine samples.
When an external field is applied across cation exchange substrate, the ion depletion appears on the anodic side when the ions are enriched on the cathodic side to fulfill mass conservation and electrical neutrality constrains. In particular when the ion exchange substrates are of round shape, the field lines passing through the membrane disk are focused at the exit pole to further enhance concentration polarization to result in a superconcentraiton spot.
GNP colorimetric assays to determine albumin are carried out using the miniaturized concentration chip containing a Nafion® cation-exchange membrane disk. Under alkaline condition when GNP solution is spiked with albumins to concentrate using the membrane disk, anionic albumins can prevent the concentrated GNP’s from aggregation and the concentrated GNP’s remain in red color even in highly salty solutions. On the other hand without efficient protections by absorbed albumins, GNP’s aggregate and change color to blue. Using smart phone camera to acquire the concentration images of non-aggregated nanoparticles, one linear correlation is found between the red color intensity and the logarithm values of albumin concentration to quantify albumin amounts. This colorimetric assay is validated to determine the samples of the main urine protein, human serum albumin at the range of clinical significance (0.1–20μM) in artificial urine matrix containing creatinine and urine. These results prove the feasibility of using the membrane-based micro-concentration device with mobile phone camera.
Aryl hydrocarbon receptor (AhR), a cellular chemical sensor, controls cellular homeostasis, and sphingosine-1-phosphate (S1P), a bioactive intermediate of sphingolipid metabolism, is believed to have ...a role in immunity and inflammation, but their potential crosstalk is currently unknown. We aimed to determine whether there is a functional linkage between AhR signaling and sphingolipid metabolism. We showed that AhR ligands, including an environmental polycyclic aromatic hydrocarbon (PAH), induced S1P generation, and inhibited S1P lyase (S1PL) activity in resting cells, antigen/IgE-activated mast cells, and mouse lungs exposed to the AhR ligand alone or in combination with antigen challenge. The reduction of S1PL activity was due to AhR-mediated oxidation of S1PL at residue 317, which was reversible by the addition of an antioxidant or in cells with knockdown of the ORMDL3 gene encoding an ER transmembrane protein, whereas C317A S1PL mutant-transfected cells were resistant to the AhR-mediated effect. Furthermore, analysis of AhR ligand-treated cells showed a time-dependent increase of the ORMDL3-S1PL complex, which was confirmed by FRET analysis. This change increased the S1P levels, which in turn, induced mast cell degranulation via S1PR2 signaling. In addition, elevated levels of plasma S1P were found in children with asthma compared to non-asthmatic subjects. These results suggest a new regulatory pathway whereby the AhR-ligand axis induces ORMDL3-dependent S1P generation by inhibiting S1PL, which may contribute to the expression of allergic diseases.
When a centrifugation-enriched sample of 100 μL containing the surface-enhanced Raman scattering (SERS) tag-bound bacteria (Salmonella in this study) is siphoned onto a glass slide next to an ...embedded thermoelectric heating chip, such a sessile droplet is quickly evaporated. As the size of the sample droplet is significantly reduced during the heating process, ionic wind streams from a corona discharge needle, stationed above the sample, sweep across the liquid surface to produce centrifugal vortex flow. Tag-bound Salmonella in the sample are then dragged and trapped at the center of droplet bottom. Finally, when the sample is dried, unlike the "coffee ring" effect, the SERS tag-bound Salmonella is concentrated in one small spot to allow sensitive detection of a Raman signal. Compared with our previous electrohydrodynamic concentration device containing only a corona discharge needle, this thermoelectric evaporation-assisted device is more time-effective, with the time of concentrating and drying about 100 μL sample reduced from 2 h to 30 min. Hence, sample throughput can be accelerated with this device for practical use. It is also more sensitive, with SERS detection of a few cells of Salmonella in neat samples achievable. We also evaluated the feasibility of using this device to detect Salmonella in food samples without performing the culturing procedures. Having spiked a few Salmonella cells into ice cubes and lettuce leaves, we use filtration and ultracentrifugation steps to obtain enriched tag-bound Salmonella samples of 200 μL. After loading an aliquot of 100 μL of sample onto this concentration device, the SERS tag signals from samples of 100 g ice cubes containing two Salmonella cells and 20 g lettuce leaf containing 5 Salmonella cells can be successfully detected.
Helicobacter pylori infection is associated with the development of several gastric diseases including gastric cancer. To reach a long-term colonization in the host stomach, H. pylori employs ...multiple outer membrane adhesins for binding to the gastric mucosa. However, due to the redundancy of adhesins that complement the adhesive function of bacteria, targeting each individual adhesin alone usually achieves nonideal outcomes for preventing bacterial adhesion. Here, we report that key adhesins AlpA/B and BabA/B in H. pylori are modified by glycans and display a two-step molecular weight upshift pattern from the cytoplasm to the inner membrane and from the inner membrane to the outer membrane. Nevertheless, this upshift pattern is missing when the expression of some enzymes related to lipopolysaccharide (LPS) biosynthesis, including the LPS O-antigen assembly and ligation enzymes WecA, Wzk, and WaaL, is disrupted, indicating that the underlying mechanisms and the involved enzymes for the adhesin glycosylation are partially shared with the LPS biosynthesis. Loss of the adhesin glycosylation not only reduces the protease resistance and the stability of the tested adhesins but also changes the adhesin-binding ability. In addition, mutations in the LPS biosynthesis cause a significant reduction in bacterial adhesion in the in vitro cell-line model. The current findings reveal that H. pylori employs a general protein glycosylation system related to LPS biosynthesis for adhesin modification and its biological significance. The enzymes required for adhesin glycosylation rather than the adhesins themselves are potentially better drug targets for preventing or treating H. pylori infection.
This paper reports notable observations regarding the ion charge states of thermally stable cytochrome c, generated using an alternating current (AC) electrospray ionization (ESI) device. An AC ESI ...sprayer entrains low‐mobility ions to accumulate at the meniscus cone tip prior to the ejection of detached aerosols to produce analyte ions. Therefore, as the solvent acidity varies, protein ions entrained in the AC cone tip are found to change conformation less significantly compared with those in the direct current (DC) cone. We acquired the AC ESI mass spectra of cytochrome c at pH range from 2 to 4. Unlike the DC ESI mass spectra showing clear conformation changes due to denaturing, the AC spectra indicated that only partial denaturing occurs even at extremely acidic pH 2. More native cytochrome c in lower charge states therefore remained. Moreover, with a solvent mixture of aqueous buffer and acetonitrile (70:30), partially denatured cytochrome c was still preserved at pH 2 by using AC ESI. Completely denatured proteins are observed at pH 2 by using DC ESI.
When solvent acidity changes, the conformation of protein ions entrained in the alternating current (AC) cone tip changes less significantly compared to those in the direct current (DC) cone. In the pH range from 2 to 4, unlike DC electrospray ionization mass spectra exhibited clear conformational changes due to denaturation, the AC spectra indicated that only partial denaturation occurred even at extremely acidic pH 2.
Special issue in memory of Prof. King‐Chuen Lin Wang, Shau‐Chun; Huang, Jer‐Shing; Chang, Yuan‐Pin ...
Journal of the Chinese Chemical Society (Taipei),
June 2023, 2023-06-00, 20230601, Letnik:
70, Številka:
6
Journal Article
Tissue stroma is known to be important in regulating Hp-mediated inflammation, but its interaction with Hp and dendritic cells (DCs) remains to be determined. To this end, the potential crosstalk ...between H. pylori (Hp) infected gastric stromal cells (Hp-GSCs) and DCs was investigated. Primary GSCs from cancerous and adjacent normal tissues were generated from gastric cancer patients, and monocyte-derived DCs were obtained from healthy individuals. Levels of cytokines and prostaglandin E
(PGE
) were measured by ELISA, and C-type lectin expression in GSCs was assessed by flow cytometry and immunohistochemistry. In a trans-well co-culture system, significantly upregulated DC-derived IL-23 expression was found when DCs were co-cultured with Hp-infected GSCs (Hp-GSCs). Further, PGE
from Hp-GSCs was discovered to possess the priming effect, which could be inhibited by anti-COLEC12 (Collectin subfamily member 12) Abs, COLEC12 knockdown or when alpha3-fucosyltransferase-null (futB; HP0651) strain of Hp was used. Also, the expression of COLEC12 was co-localized with CD90
stromal cells in cancerous tissues. Hp-GSCs-conditioned DCs were able to induce the expression of IL-17 from CD4
T cells, which could be inhibited by IL-23-neutralizing Abs. These results suggested the importance of COLEC12 as a receptor involved in Hp-stromal cell interaction and its subsequent conditioning effect on DCs.
The global pandemic of COVID-19 has created an unrivalled need for sensitive and rapid point-of-care testing (POCT) methods for the detection of infectious viruses. For the novel coronavirus ...SARS-CoV-2, the nucleocapsid protein (N-protein) is one of the most abundant structural proteins of the virus and it serves as a useful diagnostic marker for detection. Herein, we report a fiber optic particle plasmon resonance (FOPPR) biosensor which employed a single-stranded DNA (ssDNA) aptamer as the recognition element to detect the SARS-CoV-2 N-protein in 15 min with a limit of detection (LOD) of 2.8 nM, meeting the acceptable LOD of 106 copies/mL set by the WHO target product profile. The sensor chip is a microfluidic chip based on the balance between the gravitational potential and the capillary force to control fluid loading, thus enabling the power-free auto-flowing function. It also has a risk-free self-contained design to avoid the risk of the virus leaking into the environment. These findings demonstrate the potential for designing a low-cost and robust POCT device towards rapid antigen detection for early screening of SARS-CoV-2 and its related mutants.
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