Smoking and Lung Disease

Smoking and Lung Disease

Introduction

• Speaker: Stephan C. Jahn, Ph.D.
• Affiliation: Pharmacology and Therapeutics, University of Florida

Chronic Obstructive Pulmonary Disease (COPD)

• Prevalence:
    - Among the Top 10 diseases in terms of prevalence.
    - 4th leading cause of death in the U.S., following heart disease, cancer, and accidents.
• Nature of Disease:
    - Considered a progressive disease characterized by increasing severity over time.
• Symptoms:
    - Patients typically experience shortness of breath and a productive cough.
• Global Definitions:
    - COPD is defined differently across various countries and regions, indicating variability in diagnostic criteria and understanding.

Pathophysiology of COPD

• Cilia Loss:
    - Loss of cilia function, which are essential for clearing mucus and debris from the airways.
• Mucous Gland Hyperplasia:
    - Increase in the number and size of mucous glands leading to excessive mucus production.
• Inflammation:
    - Chronic inflammation in the airways contributes to obstruction and destruction.
• Fibrosis:
    - Formation of fibrous tissue, further limiting lung function.
• Loss of Elasticity:
    - The lungs lose their natural elasticity, impacting airflow.
• Alveolar Destruction:
    - Damage to the alveoli, the functional units of the lung, impairs gas exchange.

Molecular Pathogenesis of COPD

• Nrf-2 Pathway:
    - Nrf-2: A transcription factor that regulates antioxidant and anti-inflammatory genes.
    - Sequestration by Keap-1:
      - Nrf-2 is kept inactive in the cytoplasm by its interaction with Keap-1.
    - Release Mechanism:
      - Nrf-2 is released in response to Reactive Oxygen Species (ROS).
    - Diminished Activity in COPD:
      - Studies show that Nrf-2 activity is decreased in patients with COPD (Hikichi et al., J Thorac Dis. 2019;11(Suppl 17):S2129–S2140).

• Pattern Recognition Receptors (PRRs):
    - Include Toll-like receptors, which identify products of cell damage and death.
    - Cytokine Release:
      - These receptors trigger the release of interleukins, activating the innate immune system.
    - Inflammatory Response:
      - Results in increased inflammation, which is overactive in COPD (Hikichi et al., J Thorac Dis. 2019;11(Suppl 17):S2129–S2140).

• Impact of Aging:
    - Loss of elasticity and alveolar function naturally occurs with aging.
    - This process is accelerated in COPD due to ROS activation pathways linked to inflammation.
    - Specific Pathway:
      - Pathways affected include those that are PI3K-dependent (Hikichi et al., J Thorac Dis. 2019;11(Suppl 17):S2129–S2140).

Asthma

• Effects of Smoking in Adults:
    - Smoking increases bronchial reactivity to insults in adults.
    - Experimental settings show elevated levels of IgE and histamine.
    - There is no definitive connection found between adult smoking and diagnosed asthma.

• Second-hand Smoke:
    - Clear connection exists between exposure to second-hand smoke and reduced lung function.
    - FCR (Forced Expiratory Flow Rate) and FEV1 (Forced Expiratory Volume in 1 second) are critical measures.
    - Clinical correlational studies indicate a connection between mothers who smoke and children diagnosed with asthma, along with higher levels of IgE in affected children.

Smoking and Pneumonia

• Infection Rates:
    - Smokers generally do not contract a higher frequency of respiratory infections, but infections they do get are more likely to lead to deeper (more severe) infections.
    - Severe symptoms are commonly associated with pneumonia cases in smokers.
• Correlation with Influenza:
    - Smokers experience nearly twice the number of pneumonia-related deaths compared to non-smokers.
    - Rates of influenza are notably higher among smokers during epidemic periods.