Lower hypoxic ventilatory response in smokers compared to non-smokers during abstinence from cigarettes

The role of sulfur compounds in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease that brings about great social and economic burden, with oxidative stress and inflammation affecting the whole disease progress. Sulfur compounds such as hydrogen sulfide (H₂S), thiols, and persulfides/polysulfides have intrinsic antioxidant and anti-inflammatory ability, which is engaged in the pathophysiological process of COPD. Hydrogen sulfide mainly exhibits its function by S-sulfidation of the cysteine residue of the targeted proteins. It also interacts with nitric oxide and acts as a potential biomarker for the COPD phenotype. Thiols’ redox buffer such as the glutathione redox couple is a major non-enzymatic redox buffer reflecting the oxidative stress in the organism. The disturbance of redox buffers was often detected in patients with COPD, and redressing the balance could delay COPD exacerbation. Sulfane sulfur refers to a divalent sulfur atom bonded with another sulfur atom. Among them, persulfides and polysulfides have an evolutionarily conserved modification with antiaging effects. Sulfur compounds and their relative signaling pathways are also associated with the development of comorbidities in COPD. Synthetic compounds which can release H₂S and persulfides in the organism have gradually been developed. Naturally extracted sulfur compounds with pharmacological effects also aroused great interest. This study discussed the biological functions and mechanisms of sulfur compounds in regulating COPD and its comorbidities.

Aging, tobacco use and lung damages

The main two functions of the lung are the respiratory functions, dependent on ventilatory mechanics and gas exchange, and the nonrespiratory functions such as metabolic, immunological, and endocrine ones. Lung aging is secondary to the age-dependent impairment of one or more of these functions. Tobacco use accelerates lung aging and touches biological, structural and respiratory and non-respiratory functions. These changes contribute to the development of chronic pulmonary diseases and predispose to pulmonary infections in older individuals. The knowledge of these changes is very useful for better management of elderly. Lung health in aging can be improved by strategies that slow the age-related decline in lung function by acting on the environmental parameters. It is also possible to improve lung development in children and to strengthen the lungs' resistance to environmental challenges and thus to extrinsic lung aging.

Effect of Hypercapnia, an Element of Obstructive Respiratory Disorder, on Pancreatic Cancer Chemoresistance and Progression

BACKGROUND

Chronic obstructive respiratory disorders (ORDs) are linked to increased rates of cancer-related deaths. Little is known about the effects of hypercapnia (elevated CO₂) on development of pancreatic ductal adenocarcinoma (PDAC) and drug resistance.

STUDY DESIGN

Two PDAC cell lines were exposed to normocapnic (5% CO₂) and hypercapnic (continuous/intermittent 10% CO₂) conditions, physiologically similar to patients with active ORD. Cells were assessed for proliferation rate, colony formation, and chemo-/radiotherapeutic efficacy. In a retrospective clinical study design, patients with PDAC who had undergone pancreatic resection between 2002 and 2014 were reviewed. Active smokers were excluded to remove possible smoking-related protumorigenic influence. Clinical data, pathologic findings, and survival end points were recorded. Kaplan-Meier and Cox regression analyses were performed.

RESULTS

Exposure to hypercapnia resulted in increased colony formation and proliferation rates in vitro in both cell lines (MIA-PaCa-2: 111% increase and Panc-1: 114% increase; p < 0.05). Hypercapnia exposure induced a 2.5-fold increase in oxaliplatin resistance (p < 0.05) in both cell lines and increased resistance to ionizing radiation in MIA-PaCa-2 cells (p < 0.05). Five hundred and seventy-eight patients were included (52% were male, median age was 68.7 years [interquartile range 60.6 to 76.8 years]). Cox regression analysis, assessing TNM staging, age, sex, and ORD status, identified ORD as an independent risk factor for both overall survival (hazard ratio 1.64; 95% CI, 1.2 to 2.3; p < 0.05) and disease-free survival (hazard ratio 1.68; 95% CI, 1.06 to 2.67).

CONCLUSIONS

PDAC cells exposed to hypercapnic environments, which is common in patients with ORD, showed tumor proliferation, radioresistance, and chemoresistance. Patients with a history of ORD had a worse overall prognosis, suggesting that hypercapnic conditions play a role in the development and progression of PDAC and stressing the need for patient-tailored care.