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Human serum paraoxonase-1 (PON-1) is a critical antioxidant defence system against lipid oxidation. Decreased PON-1 activity has been associated with systemic oxidative stress in several disease states. We conducted a systematic review and meta-analysis of plasma/serum concentrations of PON-1 in asthma, a chronic inflammatory airway disease. The electronic databases PubMed, Web of Science, Scopus and Google Scholar were searched from inception to February 2022. In total, 8 studies in 355 asthmatic patients and 289 healthy controls were included in the meta-analysis. Serum PON-1 concentrations were significantly lower in asthmatic patients (SMD = −1.58, 95% CI −2.53 to −0.63; p = 0.001). The pooled SMD values were not substantially altered in sensitivity analysis. There was no publication bias. There were non-significant differences in PON-1 concentrations in patients with severe vs. mild-to-moderate asthma (SMD = − 0.39, 95% CI − 1.00 to 0.22, p = 0.21). Our meta-analysis has shown that serum PON-1 concentrations are significantly lower in patients with asthma, suggesting the presence of an impaired antioxidant defense in this group. [ABSTRACT FROM AUTHOR]

Patients with chronic obstructive pulmonary disease (COPD) often suffer from other conditions, such as cardiovascular disease, that further increase the risk of adverse outcomes in this group. Serum homocysteine concentrations are positively associated with cardiovascular risk and have also been reported to be increased in COPD. This meta-analysis investigated the association between homocysteine concentrations and COPD. A systematic search of publications in the electronic databases PubMed, Web of Science, Scopus, and Google Scholar, from inception to September 2021, was conducted using the following terms: "Homocysteine" or "Hcy" and "Chronic Obstructive Pulmonary Disease" or "COPD". Weighted mean differences (WMDs) were calculated to evaluate differences in homocysteine concentrations between COPD patients and non-COPD subjects. Risk of bias and certainty of evidence were assessed using the Joanna Briggs Institute Critical Appraisal Checklist and GRADE, respectively. Nine studies in 432 COPD patients (mean age 65 years, 65% males) and 311 controls (mean age 65 years, 56% males) were identified. Pooled results showed that serum homocysteine concentrations were significantly higher in patients with COPD (WMD = 2.91 µmol/L, 95% CI 2.00–3.82 µmol/L; p < 0.001; high certainty of evidence). No publication bias was observed. Our results support the hypothesis that increased homocysteine concentrations are significantly associated with COPD and may account, at least in part, for the increased cardiovascular risk in these patients. [ABSTRACT FROM AUTHOR]