The following is a summary of “Asthmatic patients with high serum amyloid A have proinflammatory HDL: Implications for augmented systemic and airway inflammation,” published in the April 2024 issue of Allergy & Immunology by Yao, et al.
Serum amyloid A (SAA) is associated with high-density lipoproteins (HDL) in the bloodstream, and its elevation has been observed in patients with asthma. However, the impact of elevated SAA levels on asthma severity remained unclear. For a study, researchers sought to identify the clinical characteristics of patients with asthma who exhibit high levels of SAA and to investigate whether HDL derived from these individuals contributes to proinflammatory responses.
SAA levels in serum samples from subjects with and without asthma were measured using ELISA. HDL isolated from patients with asthma with high SAA levels stimulated human monocytes in vitro and intravenously administered to BALB/c mice.
A threshold SAA level of ≥108.8 μg/mL was established to categorize 11% of the asthmatic cohort (n = 146) as SAA-high. Patients with asthma exhibiting high SAA levels displayed increased serum levels of C-reactive protein, IL-6, and TNF-α, along with older age and a higher prevalence of obesity and severe asthma. HDL isolated from patients with SAA-high asthma contained elevated levels of SAA compared to HDL from patients with SAA-low and induced the secretion of proinflammatory cytokines (IL-6, IL-1β, and TNF-α) from human monocytes via a formyl peptide receptor 2/ATP/P2X purinoceptor 7 axis. Intravenous administration of SAA-high HDL, but not normal HDL, to mice induced systemic inflammation and exacerbated allergen-induced neutrophilic airway inflammation and goblet cell metaplasia.
Patients with asthma have elevated SAA levels were characterized by systemic inflammation, advanced age, and a higher prevalence of obesity and severe asthma. HDL derived from these patients exhibits proinflammatory properties, and when administered intravenously to mice, it triggers systemic inflammation and exacerbates allergen-induced airway inflammation. The findings suggested that systemic inflammation induced by SAA-high HDL may contribute to the severity of asthma.
Reference: sciencedirect.com/science/article/abs/pii/S0091674923024132