Hyun Jik Kim

Background The cultures of human nasal epithelial cells (NECs) are good surrogate models for studying immune responses. Three-dimensional (3D) organoids have emerged as an alternative for nasal epithelium, serving as robust platforms for modeling respiratory viral infections. We aimed to generate human NEC organoids and to determine their cellular characteristics as an in vitro model for air-liquid interface (ALI) culture and influenza A virus (IAV) infection. Methods Primary human nasal mucosal tissues were obtained from healthy donors undergoing nasal surgery, and nasal epithelial cell (NEC) organoids were established using Matrigel-based three-dimensional culture. Differentiated NEC organoids and air–liquid interface (ALI) cultures were characterized by histology, immunostaining, electron microscopy, and quantitative real-time PCR, followed by influenza A virus (A/WSN/33 H1N1) infection assays. In addition, single-cell RNA sequencing (scRNA-seq) was performed to analyze cellular heterogeneity and differentiation trajectories of NEC organoids. Results We successfully developed human NEC organoids with using a Matrigel-based 3D culture system that recapitulates the structural characteristics and cellular composition of the human nasal epithelium. Histological results, real-time PCR, and single-cell RNA sequencing (scRNA-seq) revealed that the organoids consisted of seven different cell types and displayed a difference in the composition between the cells. The organoids displayed a much higher rate of basal progenitor cells whereas ciliated cells were less dominant. Unlike ALI cultures in which passage (P) 2 was the limit, the organoids exhibited successful and subsequent passages up to P5. Our data determined that NEC organoids are an adequate in vitro model for IAV infection and showed a sharp induction of mRNA levels for interferons (IFNs) and IFN-stimulated genes following IAV infection. Conclusions This study’s results demonstrate that human NEC organoids serve as a robust in vitro model, successfully recapitulating the biological characteristics of nasal epithelium, and could be an innovative tool for exploring distinct IFN-related innate immune responses following influenza infection.

Background and Objectives: Adherence to positive airway pressure (PAP) is often suboptimal, and current monitoring relies on device logs that, by design, cannot detect respiratory events outside the therapy window. This creates a physiological blind spot during periods of non-usage. This study aimed to demonstrate the clinical necessity of independent, continuous monitoring using a smartphone-based home sleep apnea test (S-HSAT) by validating treatment effectiveness on adherent nights and quantifying the untreated apnea burden caused by partial adherence. Methods: We prospectively monitored 63 obstructive sleep apnea (OSA) patients commencing PAP therapy. Nightly apnea–hypopnea index (AHI) and usage time were recorded simultaneously by an S-HSAT (ApnoTrack) and the PAP device over a 30-day period. Nights were categorized by the duration discrepancy between S-HSAT and PAP (full-use, ≤5 min; intermediate-use, 5–30 min; partial-use, >30 min) using physiologically and operationally derived thresholds. Results: Final analysis included 39 participants contributing 667 nights (24 participants excluded due to non-use of one or both devices). Full-use nights (46.2%) showed close agreement between S-HSAT and PAP mean AHI (2.8 ± 4.3 vs. 2.5 ± 2.0 events/h; p = 0.13). On intermediate-use and partial-use nights (20.7% and 33.1%, respectively), substantial AHI discrepancies emerged (7.3 ± 5.5 vs. 3.8 ± 3.3 and 11.0 ± 7.4 vs. 2.8 ± 2.5 events/h, respectively; both p < 0.001). Conclusions: Independent S-HSAT monitoring quantified an untreated apnea burden that is invisible to PAP logs alone, while confirming therapeutic efficacy on well-adherent nights. These findings suggest that continuous independent monitoring may help bridge the gap between prescribed therapy and actual physiological outcomes in OSA care.

Objective: Obstructive sleep apnea (OSA) frequently results from multilevel upper airway obstruction involving the palate, lateral walls, and tongue base. Among various techniques, endoscope‐guided coblation for tongue base reduction (TBR) provides precise resection with excellent hemostasis and minimal morbidity. This study aimed to evaluate the therapeutic efficacy and safety of endoscope‐guided coblation for TBR as a component of multilevel surgery in patients with moderate to severe OSA. Study Design: Case series. Setting: Single‐institution academic tertiary medical center. Subjects and Methods: The study included 92 OSA patients (85 males and 7 females) with identified tongue base (TB) narrowing in a single tertiary center. Patient demographics, subjective symptoms, polysomnography parameters, drug‐induced sleep endoscopy findings, positive airway pressure data, and postoperative complications following endoscopic coblation TBR were retrospectively reviewed. Results: The mean age of the patients was 40.8 ± 12.8 years, and the mean body‐mass index was 26.8 ± 4.0 kg/m ² . The success rate of endoscopic coblation TBR was 56.1% in moderate or severe OSA patients, with 66.7% showing significant improvement in sleep parameters. The preoperative apnea‐hypopnea index (AHI) was 47.3 ± 22.2 events/hr, which decreased to 27.8 ± 23.8 events/hr postoperatively at 6 months. Supine AHI, apnea index (AI), and lowest oxygen saturation (SpO ₂ ) were also significantly improved. Sleep efficiency and REM percentage increased substantially. Postoperative complications were minimal, with pain being the most common complaint, which rarely lasted longer than a week. Conclusion: Endoscope‐guided coblation TBR, when incorporated into multilevel sleep surgery, significantly improves polysomnographic outcomes, including AHI, oxygen saturation, and sleep efficiency, while maintaining a favorable safety profile. This approach offers a practical, cost‐effective, and minimally invasive alternative, broadening access to effective upper airway surgery for OSA patients.

The surgical treatment of obstructive sleep apnea (OSA) has evolved beyond traditional uvulopalatopharyngoplasty, which often yields inconsistent success reports. This article presents a systematic surgical protocol that tailors the type of pharyngoplasty to fit specific airway collapse patterns identified by drug-induced sleep endoscopy (DISE). In this protocol, all surgical candidates undergo DISE to evaluate the collapse pattern, with a focus on retropalatal circumferential collapse. Based on these findings, patients are selected for one of three procedures: uvuloplasty with soft palatal webbing flap pharyngoplasty for mild cases, relocation pharyngoplasty for moderate cases, or expansion sphincter pharyngoplasty for severe cases. This personalized strategy has been reported with notable improvements in surgical outcomes in appropriately selected patients. This highlights that a one-size-fits-all approach is insufficient and that a surgical strategy guided by a thorough DISE assessment is essential to select the appropriate technique and maximize success in OSA surgery.

Objectives: Here, we characterised the diversity and persistence of immunological memory cells—particularly tissue‐resident memory T (T _RM ) and B (B _RM ) cells—in the nasopharyngeal lymphoid tissues of healthy vaccinated (HV) individuals and those who experienced SARS‐CoV‐2 breakthrough infection (BR). Methods: Nasopharynx (NP) samples were obtained using brushing from HV and BR subjects. Immune cell populations were analysed using transcriptomic profiling and flow cytometry. Results: Transcriptomic profiling revealed that the NP of SARS‐CoV‐2‐infected individuals exhibited distinctive signatures of lymphocyte‐mediated immunity, underscoring its role as a key site for viral invasion and immune activation. Effector memory CD4+ and CD8+ T (T _EM ) cells, along with non‐germinal center (GC) B cells, predominated in the NP. Although overall frequencies of memory T cells were comparable between HV and BR groups, CD4+ T _EM and GC B cells were significantly enriched in the NP of BR individuals at least 1 year post infection. Notably, over 80% of CD4+ T _EM and 40% of CD8+ T _EM cells were T _RM , and more than 30% of memory B cells exhibited a B _RM phenotype. These populations of CD4+, CD8+ T _RM and B _RM persisted in the NP for over 2 years following SARS‐CoV‐2 infection or vaccination. In particular, CD4+ T _RM cells were significantly more abundant and durably maintained in the NP mucosa of BR individuals. Conclusion: Our findings identify the nasopharynx as a key site of long‐lived immunological memory, marked by persistent T _RM and B _RM cells after SARS‐CoV‐2 exposure.

Objective: While palatal surgery is an established treatment for obstructive sleep apnea (OSA), variability in outcomes has prompted investigation into factors predicting surgical success. This study aimed to evaluate whether preoperative polysomnographic (PSG) parameters, along with drug‐induced sleep endoscopy (DISE) findings, can predict surgical outcomes in patients with OSA. Methods: This retrospective study included 56 adult patients with OSA who completed both pre‐ and postoperative PSG and DISE assessments. Patients were classified into a successful outcome group (SG; ≥ 20 events/h reduction in apnea–hypopnea index [AHI]) or a worse outcome group (WG; ≥ 20 events/h increase in AHI). Baseline PSG and DISE findings were compared between groups, and multivariate regression analysis was used to identify independent predictors of surgical success. Results: Patients in the SG exhibited significantly higher preoperative AHI and larger tonsil size compared to those in the WG. While DISE collapse patterns did not differ significantly between groups, key differences emerged in PSG metrics. SG patients had a significantly greater proportion of non‐REM stage N3 sleep within non‐REM sleep and a lower arousal index, both of which were independently associated with improved surgical outcomes. Additionally, respiratory events were more prominent during non‐rapid eye movement sleep in SG patients. Multivariate analysis confirmed that a greater proportion of non‐REM stage N3 sleep and lower arousal index were strong predictors of postoperative AHI reduction. Conclusions: These findings may offer more reliable predictors of which OSA patients will benefit from sleep surgery and underscore the importance of incorporating detailed PSG analysis into preoperative evaluations. Level of Evidence: 4.