Solitary chemosensory cells (SCCs) of the nasal cavity are specialized epithelial chemosensors that respond to irritants through the canonical taste transduction cascade involving Gα-gustducin and transient receptor potential melastatin 5. When stimulated, SCCs trigger peptidergic nociceptive (or pain) nerve fibers, causing an alteration of the respiratory rate indicative of trigeminal activation. Direct chemical excitation of trigeminal pain fibers by capsaicin evokes neurogenic inflammation in the surrounding epithelium. In the current study, we test whether activation of nasal SCCs can trigger similar local inflammatory responses, specifically mast cell degranulation and plasma leakage. The prototypical bitter compound, denatonium, a well-established activator of SCCs, caused significant inflammatory responses in WT mice but not mice with a genetic deletion of elements of the canonical taste transduction cascade, showing that activation of taste signaling components is sufficient to trigger local inflammation. Chemical ablation of peptidergic trigeminal fibers prevented the SCC-induced nasal inflammation, indicating that SCCs evoke inflammation only by neural activity and not by release of local inflammatory mediators. Additionally, blocking nicotinic, but not muscarinic, acetylcholine receptors prevents SCC-mediated neurogenic inflammation for both denatonium and the bacterial signaling molecule 3-oxo-C12-homoserine lactone, showing the necessity for cholinergic transmission. Finally, we show that the neurokinin 1 receptor for substance P is required for SCC-mediated inflammation, suggesting that release of substance P from nerve fibers triggers the inflammatory events. Taken together, these results show that SCCs use cholinergic neurotransmission to trigger peptidergic trigeminal nociceptors, which link SCCs to the neurogenic inflammatory pathway.rhinitis | innate immunity | quorum sensing | chemesthesis | airway irritation
We compared the absorption of eicosapentaenoic (EPA, 20:5n-3), docosahexaenoic (DHA, 22:6n-3), and decanoic acids in mesenteric lymph duct-cannulated rats following intragastric administration of two oils with different intramolecular triacylglycerol structures. One oil had a specific triacylglycerol structure with EPA and DHA located in the sn-2 position and decanoic acid in the sn-1 and sn-3 positions (specific M-n3-M) whereas the other oil had a random fatty acid distribution (random M-n3-M). The mol% (mol/100 mol total fatty acids) of fatty acids in the two oils was similar, with approximately 66 mol% of decanoic acid and 22 mol% of EPA and DHA. The lymphatic transport (microgram/min) of EPA and DHA as well as the mol% in the total lymph lipids were significantly (both P < 0.01) increased following intragastric administration of specific M-n3-M compared with random M-n3-M. The mol% of decanoic acid in the total lymph lipids was significantly (P < 0.01) higher after random M-n3-M compared with specific M-n3-M but the transport (microgram/min) of decanoic acid was not significantly different. We conclude that under our experimental conditions specific M-n3-M with EPA and DHA predominantly in the sn-2 position of the triacylglycerols was a more readily absorbed source of EPA and DHA and in this context should be investigated further for the potential use in clinical nutrition.
A data set consisting of 712 compounds was used for classification into two classes with respect to membrane permeation in a cell-based assay: (0) apparent permeability (P(app)) below 4 x 10(-6) cm/s and (1) P(app) on 4 x 10(-6) cm/s or higher. Nine molecular descriptors were calculated for each compound and Nearest-Neighbor classification was applied using five neighbors as optimized by full cross-validation. A model based on five descriptors, number of flex bonds, number of hydrogen bond acceptors and donors, and molecular and polar surface area, was selected by variable selection. In an external test set of 112 compounds, 104 compounds were classified and 8 compounds were judged as "unknown". Among the 104 compounds, 16 were misclassified corresponding to a misclassification rate of 15% and no compounds were falsely predicted in the nonpermeable class.
Although T lymphocytes are present in the genital mucosa, their function in sexually transmitted diseases is unproven. To determine if cervical T cells mediate HIV-specific cytolysis, mononuclear cells in cytobrush specimens from HIV-1-infected women were stimulated in vitro with antigen. Resultant cell lines lysed autologous targets expressing HIV-1 proteins in 12/19 (63%) subjects, and these responses were detected intermittently on repeated visits. All 8 subjects with blood CD4+ counts ⩾500 cells/μl had HIV-1-specific cervical CTL, whereas only 4/11 with counts <500 cells/μl had detectable responses (P = 0.008). Class II MHC– restricted CD4+ CTL clones lysed targets expressing Env gp41 or infected with HIV-1. Class I MHC-restricted CD8+ clones recognized HIV-1 Gag- or Pol-expressing targets, and the epitopes were mapped to within 9–20 amino acids. Comparisons of intra-individual cervical and blood CTL specificities indicate that epitopes recognized by CTL in the cervix were commonly recognized in the blood. These studies provide the first definitive evidence for an MHC-restricted effector function in human cervical lymphocytes.
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