Flow chart of the study implementation.

COX-2 functions in the tumor microenvironment.

Trends in age-adjusted prevalence of chronic obstructive pulmonary disease (COPD) among adults aged ≥50 years, stratified by gender and race, the Health and Retirement Study, the United States, 2000–2020. (A) Trends in COPD prevalence by gender; (B) trends in COPD prevalence by race.

Integrated digital health in a possible future chronic obstructive pulmonary disease clinic.

Nonspecific and specific immune responses during primary and secondary infections. The innate immune cells are activated after immune recognition and initiate the innate immune response leading to adaptive immunity stimulation, cytokine secretion, pathogen elimination, and trained immunity. The classical adaptive immune memory involves gene recombination in T and B cells, which confers often long-term and pathogen-specific protection. Trained immunity enhances inflammatory and antimicrobial properties in innate immune cells. Both of them provide protection from re-infection.

The lungs possess a strong defense system of mucus, structural cells, immune cells, and extracellular matrix that clears or inactivates causative agents. The immune defense mechanism of the lungs consists of innate immunity and adaptive immunity, and mucociliary clearance is the first line of defense in innate immunity. Cells such as alveolar epithelial cells, macrophages, and dendritic cells bind to pathogen-associated molecular patterns on their surfaces through pattern recognition receptors when a pathogen breaks through the immune defenses of airway epithelial surfaces and recognizes the corresponding pathogen. Various Tissue-Resident Lymphocytes in the lungs secrete different cytokines stimulated by antigens, recruit effector cell subsets and provoke corresponding immune responses, eliminating pathogens. Adaptive immunity mainly includes cellular immunity mediated by T cells and humoral immunity mediated by B cells. The normal flora in the lungs also plays a good protective role for the host. They can also contend for ecological niches with opportunistic pathogens and foreign pathogens, decreasing the likelihood of pathogenic infection colonization.

Flow of the study

Grayscale CT image statistics accurately distinguish the severity of COVID-19-related lung conditions