Objective:To investigate the possible mechanisms underlying the involvement of the gut microbiota metabolite trimethylamine oxide (TMAO) in the pathogenesis of chronic spontaneous urticaria (CSU) .Methods:From June 2023 to June 2024, 67 CSU patients were enrolled from the Dermatology and Cosmetic Center, the Third Affiliated Hospital of Chongqing Medical University, and 69 age-matched healthy controls were also collected at the same time. Serum TMAO levels in both groups were measured using enzyme-linked immunosorbent assay (ELISA) , and D-dimer levels were collected from the CSU patients. A degranulation model was established in rat basophilic leukemia RBL-2H3 cells using anti-DNP IgE/DNP-BSA (IgE/Ag group) ; these cells were additionally grouped to be treated with different concentrations of TMAO (IgE/Ag+10 μmol/L TMAO group, IgE/Ag + 50 μmol/L TMAO group, IgE/Ag + 100 μmol/L TMAO group) ; untreated RBL-2H3 cells served as a blank control group. To investigate the effect of the extracellular signal-regulated kinase (ERK) phosphorylation inhibitor U0126 on the action of TMAO, RBL-2H3 cells were divided into another 5 groups: blank group, IgE/Ag group, IgE/Ag + 1 μmol/L U0126 group, IgE/Ag + 100 μmol/L TMAO group, and IgE/Ag + 100 μmol/L TMAO + 1 μmol/L U0126 group. In vivo, a localized allergic reaction model was established in the ears of C57BL/6 mice using anti-DNP IgE/DNP-BSA (IgE/Ag group) , and additional groups included blank group, IgE group, IgE/Ag + solvent (DMSO) group, and IgE/Ag + 10 μg/μl TMAO group. ELISA was performed to detect levels of inflammatory mediators in cell culture supernatants and mouse serum. Toluidine blue staining was employed to observe mast cell degranulation in the cell experiment and mouse ear tissue samples, Evans blue staining to assess vascular permeability in mouse ear tissue samples, and Western blot analysis to detect the ERK phosphorylation levels. The t test was used for comparisons between two groups, and one-way analysis of variance for multiple comparisons. Results:Serum TMAO levels were significantly higher in the 67 CSU patients than in the 69 healthy controls ( t = 13.27, P < 0.001) . Among the 32 CSU patients with available data about D-dimer, serum TMAO levels were positively correlated with D-dimer levels ( r = 0.62, P < 0.001) . In RBL-2H3 cell experiments, degranulation rates were significantly higher in the IgE/Ag + 10, 50, and 100 μmol/L TMAO groups than in the IgE/Ag group; morphologically, RBL-2H3 cells treated with 10, 50, and 100 μmol/L TMAO became increasingly rounded; 50 and 100 μmol/L TMAO significantly promoted the production of β-hexosaminidase (β-Hex) , interleukin-6 (IL-6) , and tumor necrosis factor-α (TNF-α) (all P < 0.01) , and upregulated ERK phosphorylation levels ( P < 0.01) ; the levels of ERK phosphorylation, IL-6, TNF-α, and β-Hex were significantly lower in the IgE/Ag + U0126 group than in the IgE/Ag group, as well as lower in the IgE/Ag + TMAO + U0126 group than in the IgE/Ag + TMAO group (all P < 0.001) . In the mouse model of localized allergic reaction, the IgE/Ag + TMAO group showed increased vascular permeability, edema degree, and mast cell degranulation, as well as significantly elevated ERK phosphorylation levels and TNF-α expression in mouse ear tissues compared with the IgE/Ag + DMSO group (both P < 0.05) . Conclusion:Elevated serum TMAO may participate in the pathogenesis of CSU by upregulating ERK phosphorylation levels in mast cells and skin tissues, thereby promoting IgE/Ag-mediated degranulation of effector cells and production of inflammatory mediators.

Objective:To investigate the possible mechanisms underlying the involvement of the gut microbiota metabolite trimethylamine oxide (TMAO) in the pathogenesis of chronic spontaneous urticaria (CSU) .Methods:From June 2023 to June 2024, 67 CSU patients were enrolled from the Dermatology and Cosmetic Center, the Third Affiliated Hospital of Chongqing Medical University, and 69 age-matched healthy controls were also collected at the same time. Serum TMAO levels in both groups were measured using enzyme-linked immunosorbent assay (ELISA) , and D-dimer levels were collected from the CSU patients. A degranulation model was established in rat basophilic leukemia RBL-2H3 cells using anti-DNP IgE/DNP-BSA (IgE/Ag group) ; these cells were additionally grouped to be treated with different concentrations of TMAO (IgE/Ag+10 μmol/L TMAO group, IgE/Ag + 50 μmol/L TMAO group, IgE/Ag + 100 μmol/L TMAO group) ; untreated RBL-2H3 cells served as a blank control group. To investigate the effect of the extracellular signal-regulated kinase (ERK) phosphorylation inhibitor U0126 on the action of TMAO, RBL-2H3 cells were divided into another 5 groups: blank group, IgE/Ag group, IgE/Ag + 1 μmol/L U0126 group, IgE/Ag + 100 μmol/L TMAO group, and IgE/Ag + 100 μmol/L TMAO + 1 μmol/L U0126 group. In vivo, a localized allergic reaction model was established in the ears of C57BL/6 mice using anti-DNP IgE/DNP-BSA (IgE/Ag group) , and additional groups included blank group, IgE group, IgE/Ag + solvent (DMSO) group, and IgE/Ag + 10 μg/μl TMAO group. ELISA was performed to detect levels of inflammatory mediators in cell culture supernatants and mouse serum. Toluidine blue staining was employed to observe mast cell degranulation in the cell experiment and mouse ear tissue samples, Evans blue staining to assess vascular permeability in mouse ear tissue samples, and Western blot analysis to detect the ERK phosphorylation levels. The t test was used for comparisons between two groups, and one-way analysis of variance for multiple comparisons. Results:Serum TMAO levels were significantly higher in the 67 CSU patients than in the 69 healthy controls ( t = 13.27, P < 0.001) . Among the 32 CSU patients with available data about D-dimer, serum TMAO levels were positively correlated with D-dimer levels ( r = 0.62, P < 0.001) . In RBL-2H3 cell experiments, degranulation rates were significantly higher in the IgE/Ag + 10, 50, and 100 μmol/L TMAO groups than in the IgE/Ag group; morphologically, RBL-2H3 cells treated with 10, 50, and 100 μmol/L TMAO became increasingly rounded; 50 and 100 μmol/L TMAO significantly promoted the production of β-hexosaminidase (β-Hex) , interleukin-6 (IL-6) , and tumor necrosis factor-α (TNF-α) (all P < 0.01) , and upregulated ERK phosphorylation levels ( P < 0.01) ; the levels of ERK phosphorylation, IL-6, TNF-α, and β-Hex were significantly lower in the IgE/Ag + U0126 group than in the IgE/Ag group, as well as lower in the IgE/Ag + TMAO + U0126 group than in the IgE/Ag + TMAO group (all P < 0.001) . In the mouse model of localized allergic reaction, the IgE/Ag + TMAO group showed increased vascular permeability, edema degree, and mast cell degranulation, as well as significantly elevated ERK phosphorylation levels and TNF-α expression in mouse ear tissues compared with the IgE/Ag + DMSO group (both P < 0.05) . Conclusion:Elevated serum TMAO may participate in the pathogenesis of CSU by upregulating ERK phosphorylation levels in mast cells and skin tissues, thereby promoting IgE/Ag-mediated degranulation of effector cells and production of inflammatory mediators.

Background Studies showed that activation of microglia-derived nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a key role in the neurodegenerative diseases and neural cell death in central nervous system.The effect of NADPH on cone degeneration have been determined in rd rats,its role in rod degeneration is relatively less studied.Objective This study was to study the expression of NADPH oxidase in the retinal degenerative process in rd mice and further explore its role in the photoreceptor degeneration.Methods rd Mice at postnatal day 8 (P8),P10,P12,P14,P16 and P18 were collected.The mice were sacrificed,and retinal sections,RNAs and proteins were prepared in above-mentioned time points.The expressions of the gp91 phox,a major subunit of NADPH oxidase,in transcript level and protein level in the retinas were semi-quantitatively detected by real-time PCR and Western blot respectively.Expression of gp91phox was localized in the rd retinas as ageing by immunohistochemstry,and the co-expression of gp91phox with CD11b,a specific marker of microglial cells,was assayed by immunofluorescent double labeling.The C57BL/6N mice were served as controls.The use and care of the animals complied with the Guideline of ARVO.Results Real-time PCR showed that gp91phox mRNA was not expressed in the retinas of C57BL/6N mice.Gp91phox mRNA was found to have less expressed in retinas of P8 rd mice.With aging,the expression level of gp91phox mRNA (gp91phox mRNA/β-actin) in rd mouse retinas was gradually increased with the highest level in P14 mice(1.136±0.370).A significant difference was seen in the gp91 phox mRNA expression among various groups of mice (F=17.81,P =0.00),and gp91phox mRNA expression was significantly elevated in P10,P12,P14,P16 and P18 rd mice compared with P8 rd mice(all at P＜0.05).The expression level of gp91phox protein (A value) in the retinas presented with a similar trend in the rd mice,with a significant difference among the various ages of rd mice and C57BL/6N mice (F =354.00,P＜0.01).The expression level of gp91 phox protein was increased in the rd mice in comparison with the C57BL/6N mice (all at P＜0.05).Immunochemistry revealed that the positive response cells for gp91phox increased in the inner layers of retinas in P10 rd mice and peaked in P14 mice.Immunofluorescent double labeling exhibited that gp91phox were seen to present a co-expression with CD11b,showing an orange fluorescence.Conclusions Expression of NADPH oxidase in the rctinas in the rd mice up-regulates and is parallels to the microglial activation and photoreceptor degeneration,suggesting that NADPH oxidase plays a role in the retinal dystrophy associated with microglial activation.

Objective To study the development of hereditary dystrophic retina of rd mice and photoreceptors apoptosis. Methods Retinal sections of rd mice and their controls at different ages ranging from postnatal days 5 to 40 were examined by morphological(light and electronic microscope), morphometric and TUNEL analysis. Results Compared with age-matched control mice, the retinal dystrophy of rd mice began at postnatal days 10, resulting in rapid loss of photoreceptors and reaching a peak at postnatal days 18. TUNEL postitive nucleus of photoreceptor cells emerged from postnatal days 10 and reached a peak at postnatal days 14 and 16. Ultrastructure of photoreceptor cell layer showed marked nuclear pyknotosis and chromatin margination. Apoptotic bodies of photoreceptor cells were observed.Conclusion Rd mice retina degenerated during the process of maturity. Photoreceptor cell death occurred through apoptosis.