Background: Pseudomembranous necrotizing laryngotracheobronchitis refers to an acute diffuse necrotizing inflammation in the mucosa of the larynx, trachea, and bronchus. It often occurs in infants and children having viral infections secondary to bacterial infections. Mycoplasma pneumoniae (M. pneumoniae) is a common pathogen that causes pneumonia in children. In recent years, serious complications due to M. pneumoniae infection, including necrotizing pneumonia, pulmonary embolism, and pleural effusion, have been increasingly reported. Case presentation: An 11-year-old girl was admitted to our unit with cough, fever, and hoarseness persistent for a week. The results of the M. pneumoniae serological test, PCR examination with bronchial aspirate and bronchoalveolar lavage fluid (BALF), next-generation sequencing (mNGS) for BALF, all suggested the presence of M. pneumoniae infection. High-resolution CT scanning of the chest showed inflammation of the middle and lower lobes of the right lung. By bronchoscopy, the necrosis of the vocal cords, trachea, and bronchial mucosa was observed; each bronchial lumen contained a large amount of white viscous sputum. Pathological findings for bronchial mucosa suggested inflammatory necrosis. After administration of azithromycin and glucocorticoids, the symptoms of the patients were ameliorated. After 2 weeks post-discharge, the X-ray scan of her chest indicated the pneumonia resolution in the right lung. Conclusions: In patients with pneumonia due to M. pneumoniae infection, which causes obvious hoarseness, bronchoscopy is necessary even if the lung lesions are not massively consolidated. When necrotizing lesions of the larynx, trachea, and bronchi are detected by bronchoscopy, the necrotic tissues in the corresponding parts should be conducted tissue biopsy for pathological examination. Apart from macrolide antibiotics, the administration of small doses of glucocorticoids is necessary.

To evaluate the role of serum cytokines in the pathogenesis of respiratory syncytial virus (RSV) infection in infants with low birth weight (LBW). A prospective observational study was performed, and hospitalized children with lower respiratory tract infection (LRTI) were recruited. Three hundred fifty-eight patients < 1 year met the inclusion criteria: 116 patients had only RSV infection (RSV group); 242 patients had no RSV or other specific pathogen (non-RSV group). Serum interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) were detected through flow cytometry. No significant differences in serum IL-2, 4, 6, 10, and IFN-γ levels were observed between the RSV and non-RSV groups. For RSV infected infants with or without wheezing, delivery mode had no obvious effect on the changes of serum cytokine levels. However, the level of IL-6 in the RSV-infected infants with LBW was significantly higher than that in infants with normal birth weight. Serum IL-6 level was significantly increased in RSV infected infants with LBW. It is likely that the specific serum cytokine pattern will contribute to our understanding of the pathogenesis of RSV infections, especially in RSV-infected infants with LBW.

Obesity, a rising global health issue, has been linked to the exacerbation of asthma, increasing both the risk of onset and disease severity. High-fat diet (HFD) has been shown to influence immune responses and worsen asthma in murine models, although the exact mechanisms remain unclear. In our study, we found that HFD significantly reduced the population of regulatory T cells (Tregs) in the lungs and led to increased eosinophilic inflammation in asthma. HFD was linked to alterations in lipid metabolism, particularly through the activation of the lipogenic enzyme acetyl-CoA carboxylase (ACC1) and inhibition of fatty acid oxidation. Additionally, treatment with Etomoxir, a CPT-1a inhibitor, diminished Treg proportions and Foxp3 expression. We also revealed that the E3 ubiquitin ligase ITCH, which regulates Treg function, was downregulated at the protein level under HFD conditions, despite unchanged mRNA levels. Overall, our research findings highlight the impact of high-fat diets on Treg function and immune regulation, providing insights for potential therapeutic strategies targeting lipid metabolism in inflammatory diseases like asthma.

BACKGROUND Subglottic stenosis (SGS) is a life-threatening airway narrowing often acquired after prolonged intubation in infants. Although severe cases have historically required open surgery, emerging endoscopic techniques such as laser therapy, balloon dilation, and cryotherapy provide less invasive alternatives with promising outcomes. This case report describes a 2-month-old female infant who developed subglottic stenosis after intubation and mechanical ventilation for acute respiratory failure due to pertussis pneumonia. CASE REPORT A 2-month-old female infant with a history of pertussis pneumonia requiring 10 days of intubation presented with respiratory distress and stridor. Diagnostic imaging and flexible laryngoscopy confirmed grade 3 SGS (Cotton-Myer classification). She underwent a multimodal endoscopic approach, including holmium laser ablation (0.5-1.0 J/pulse) for fibrotic tissue removal, balloon dilation (6 mm, 14 atmospheres) to expand the stenotic segment, and cryotherapy (-70°C) to minimize scar formation. Immediate post-procedural improvement was observed, and oxygen was gradually tapered by day 5. Follow-up fiber laryngoscopy at 1 month demonstrated sustained airway patency without restenosis. CONCLUSIONS This case supports the efficacy of combined endoscopic modalities for severe pediatric SGS, offering advantages over open surgery, including reduced morbidity and faster recovery. Long-term studies are needed to confirm durability, particularly for high-grade stenosis. Standardized protocols for laser settings, balloon sizing, and cryotherapy duration should be established to optimize outcomes.