Background/Objectives: Chronic rhinosinusitis with nasal polyps (CRSwNP) is associated with epithelial remodeling, impaired mucociliary clearance, and altered nitric oxide (NO) metabolism. However, cell type-specific mechanisms underlying epithelial NO signaling remain poorly understood. This study investigated NO-related signaling in differentiated human sinonasal epithelial cells. Methods: Human sinonasal tissues were obtained from patients with CRSwNP (n = 20) and control subjects (n = 20). Air–liquid interface (ALI) cultures were established from donor-derived epithelial cells. Ciliated and non-ciliated cells were identified by immunostaining for acetylated α-tubulin and BCAM. Expression of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) was analyzed by quantitative RT-PCR. Intracellular NO-related fluorescence signals were evaluated using DAF-FM fluorescence imaging. Results: CRSwNP tissues exhibited significantly increased iNOS expression and elevated iNOS/eNOS ratios, whereas eNOS expression did not differ significantly from that in controls. ALI cultures reproduced differentiated sinonasal epithelium containing both ciliated and non-ciliated cell populations. DAF-FM fluorescence signals were significantly higher in ciliated cells than in non-ciliated cells (80.3 ± 25.3 vs. 49.3 ± 21.1). Non-selective NOS inhibition markedly reduced fluorescence signals in both cell types, whereas selective iNOS inhibition reduced but did not abolish signals in ciliated cells. Conclusions: NO-related signaling appears to differ among epithelial cell subtypes. Persistence of fluorescence signals after selective iNOS inhibition suggests a contribution of constitutive NOS activity in ciliated cells, whereas non-ciliated cells appear to rely more heavily on iNOS-dependent pathways. These findings support the hypothesis that altered epithelial NO signaling contributes to epithelial dysfunction and impaired mucociliary homeostasis in CRSwNP.

Background/Objectives: Chronic rhinosinusitis with nasal polyps (CRSwNP) is charac-terized by epithelial remodeling, impaired mucociliary clearance, and altered nitric oxide (NO) metabolism. However, the cell type–specific mechanisms of NO production and the functional roles of nitric oxide synthase (NOS) isoforms in sinonasal epithelial cells remain unclear. This study investigated NO production dynamics in air–liquid in-terface (ALI) cultures of human sinonasal epithelial cells. Methods: Human sinonasal epithelial cells were differentiated under ALI conditions. Expression of inducible NOS (iNOS) and endothelial NOS (eNOS) was analyzed by quantitative RT-PCR. Intracellular NO production was evaluated using the NO-sensitive fluorescent probe DAF-FM com-bined with laser scanning confocal microscopy. Cell type–specific NO production was examined in ciliated and non-ciliated epithelial cells using the NOS inhibitors L-NAME and 1400W. Results: CRSwNP tissues demonstrated significantly increased iNOS ex-pression and elevated iNOS/eNOS ratios compared with controls, whereas eNOS ex-pression showed no significant difference. ALI cultures successfully reproduced dif-ferentiated sinonasal epithelium containing ciliated and basal cells. DAF-FM fluores-cence revealed significantly greater NO production in ciliated epithelial cells than in non-ciliated cells. Non-selective NOS inhibition by L-NAME markedly suppressed NO production in both cell types, whereas selective iNOS inhibition by 1400W reduced but did not abolish NO production in ciliated cells. Conclusions: NO production mecha-nisms differ according to sinonasal epithelial cell subtype. Ciliated epithelial cells maintain both eNOS- and iNOS-dependent NO production, whereas non-ciliated cells predominantly rely on iNOS-derived NO. Dysregulated spatial NO signaling associated with ciliated cell loss may contribute to epithelial dysfunction and chronic inflammation in CRSwNP.

Backgrounds: Many reported rates of positive results by nicking enzyme amplification reaction (NEAR) applied together with the Abbott ID NOW™ COVID-19 (AIN) test and dry patient samples is lower than rates provided by other nucleic acid amplification tests. Few studies have used fresh samples, however. Methods: We conducted this retrospective study using fresh samples to determine the correlations among fever, associated symptoms, and the NEAR detection rate. Quarantined cases of suspected SARS-CoV-2 infection at Kunimoto ENT clinic (Jan 14, 2022–May 7, 2023) who had been in close contact with SARS-CoV-2-infected individuals were enrolled. Specimens were collected by the thin-diameter nasal sterile swab from the nasopharynx and examined immediately. We evaluated the positive-result rates, fever, and symptoms. Results: The total number of close-contact patients evaluated was 661 and AIN-positive cases was 427. The detection rate in the fever ≥37.4°C patients was 97% (257/266), significantly higher than the corresponding rate in the <37.4°C patients (170/395) (p<0.00001). The detection rate in the patients with ≤1 symptoms other than fever was 98% (394/402). Conclusions: These results suggest that the AIN results are sufficiently dependable when fresh samples are obtained from patients with a fever ≥37.4°C, and with more than one symptom.