Mechanistic Insights into the Effects of Astaxanthin on Asthma in Mice: A Combined Transcriptomic and Metabolomic Analysis

Background Asthma is a complex disease characterised by chronic airway inflammation and airway remodelling, and its pathogenesis involves a variety of factors such as inflammatory response, oxidative stress and immunomodulatory imbalance. Although existing treatments (e.g., glucocorticosteroids and β2 agonists) are effective in controlling symptoms, some patients still suffer from treatment resistance or drug side effects, so it is important to explore new therapeutic strategies and targets. In recent years, astaxanthin has received much attention for its potent antioxidant and anti-inflammatory activities. Astaxanthin is able to play a protective role in a variety of inflammatory, immune diseases by scavenging free radicals and inhibiting inflammatory pathways such as NF-κB. However, studies on astaxanthin in asthma are still relatively limited and mostly focus on a single mechanism using a single histological technique, which makes it difficult to comprehensively reveal the regulatory network of astaxanthin at the gene and metabolic levels. The aim of this study was to investigate the ameliorative effects of oral astaxanthin on asthma symptoms by integrating metabolomics and transcriptomics analyses, and to screen potential asthma-related biomarkers and therapeutic targets. Method Seventy-five female BALB/C mice (SPF grade, 6-8 weeks old) were divided into five groups on the basis of randomisation: the blank control group (NC), the model group (OVA), the dexamethasone group (DEX), the astaxanthin low-dose group (ASTA-L), and the astaxanthin high-dose group (ASTA-H), and the mice in the remaining four groups were injected intraperitoneally with 0.01% ovoacidin (OVA) and 0.01% ovoacidin (OVA) on days 0, 7, and 14, respectively. The asthma model was constructed by intraperitoneal injection of 0.01% ovalbumin on days 0, 7 and 14, and nebulisation of 2.5% ovalbumin every other day from day 21 onwards. dexamethasone and astaxanthin were administered to the DEX group, the ASTA-L group (25 mg/kg), and the ASTA-H group (50 mg/kg) by gavage 3 hours before each nebulisation. The body weight and food intake of mice in each group were observed weekly. After 4 weeks of continuous nebulisation, 5 mice in each group were anaesthetised and bronchoalveolar lavage was performed to collect the lavage fluid to calculate the total cell count. The remaining 10 eyes were blood sampled and killed, and serum interleukin 4 (IL-4), interleukin 6 (IL-6), interleukin 13 (IL-13), immunoglobulin E (IgE), superoxide dismutase (SOD) levels were measured, and the lung wet/dry ratios were calculated, and the lung tissues were subjected to histological staining by HE, MASSON, and PAS, and analyses of transcriptomics and nontarget metabolomics. Screening of differentially expressed genes(DEGs) and metabolites(DEGs), joint study to construct gene metabolic network to analyse core pathways. Result (1) Compared with the OVA group, the lung dry-to-wet ratio and the total number of cells in the bronchoalveolar lavage fluid were reduced in the ASTA-L and ASTA-H groups (P<0.001) ASTA-H group was more obvious. (2) HE, MASSON, and PAS staining analysis showed that compared with the OVA group, the airway wall inflammatory cell infiltration, pulmonary septal thickness, collagen deposition, and glycogen deposition area were improved in the ASTA-L and ASTA-H groups, but the improvement was more significant in the ASTA-H group compared with the ASTA-L group. (3) Serum levels of IL-4, IL-6, IL-13, and IgE were reduced and SOD activity was increased in the ASTA-H group compared with the OVA group (P<0.001). (4) Transcriptomics analysed 20 genes including Gstt1, Gstm1 and Adh1, and metabolomics analysed 8 metabolites including glyceraldehyde-1,3-bisphosphate. These genes and metabolites were mainly involved in key processes such as inflammatory response, oxidative stress and immune regulation. (5) Combined analyses further revealed that astaxanthin up-regulates Adh1 expression by activating the expression of glyceraldehyde-1,3-bisphosphate, and the up-regulation of Adh1 further contributes to the synthesis of retinyl acetate. Conclusion Astaxanthin attenuates airway inflammation, oxidative stress and immune stress in asthmatic mice. The mechanism may be related to the activation of glyceraldehyde-1,3-bisphosphate up-regulation of Adh1 expression contributing to the synthesis of retinyl acetate.