Mycoplasma gallisepticum (MG) is recognized as a principal causative agent of avian chronic respiratory disease, inflicting substantial economic losses upon the poultry industry. However, the extensive use of conventional antibiotics has resulted in the emergence of drug resistance and various challenges in their clinical application. Consequently, there is an urgent need to identify effective therapeutic agents for the prevention and treatment of mycoplasma-induced respiratory disease in avian species. AMP-activated protein kinase (AMPK) holds significant importance as a regulator of cellular energy metabolism and possesses the capacity to exert an anti-inflammatory effect by virtue of its downstream protein, SIRT1. This pathway has shown promise in counteracting the inflammatory responses triggered by pathogenic infections, thus providing a novel target for studying infectious inflammation. Quercetin possesses anti-inflammatory activity and has garnered attention as a potential alternative to antibiotics. However, there exists a gap in knowledge concerning the impact of this activation on MG-induced inflammatory damage. To address this knowledge gap, we employed AlphaFold2 prediction, molecular docking, and kinetic simulation methods to perform a systematic analysis. As expected, we found that both quercetin and the AMPK activator AICAR activate the chicken AMPKγ1 subunit in a similar manner, which was further validated at the cellular level. Our project aims to unravel the underlying mechanisms of quercetin’s action as an agonist of AMPK against the inflammatory damage induced by MG infection. Accordingly, we evaluated the effects of quercetin on the prevention and treatment of air sac injury, lung morphology, immunohistochemistry, AMPK/SIRT1/NF-κB pathway activity, and inflammatory factors in MG-infected chickens. The results confirmed that quercetin effectively inhibits the secretion of pro-inflammatory cytokines such as IL-1β, TNF-α, and IL-6, leading to improved respiratory inflammation injury. Furthermore, quercetin was shown to enhance the levels of phosphorylated AMPK and SIRT1 while reducing the levels of phosphorylated P65 and pro-inflammatory factors. In conclusion, our study identifies the AMPK cascade signaling pathway as a novel cellular mediator responsible for quercetin’s ability to counter MG-induced inflammatory damage. This finding highlights the potential significance of this pathway as an important target for anti-inflammatory drug research in the context of avian respiratory diseases.

Hyperlipidemia is a risk factor for the development of fatty liver and cardiovascular diseases such as atherosclerosis and coronary heart disease, and hence, cholesterol-lowering drugs are considered important and effective in preventing cardiovascular diseases. Thus, researchers in the field of new drug development are endeavoring to identify new types of cholesterol-lowering drugs. 3β-hydroxysterol-Δ(24)-reductase (DHCR24) catalyzes the conversion of desmosterol to cholesterol, which is the last step in the cholesterol biosynthesis pathway. We speculated that blocking the catalytic activity of DHCR24 could be a novel therapeutic strategy for treating hyperlipidemia. In the present study, by virtually screening the DrugBank database and performing molecular dynamics simulation analysis, we selected four potential DHCR24 inhibitor candidates: irbesartan, risperidone, tolvaptan, and conivaptan. All four candidates showed significant cholesterol-lowering activity in HepG2 cells. The experimental mouse model of hyperlipidemia demonstrated that all four candidates improved high blood lipid levels and fat vacuolation in the livers of mice fed with a high-fat diet. In addition, Western blot analysis results suggested that irbesartan reduced cholesterol levels by downregulating the expression of the low-density lipoprotein receptor. Finally, the immune complex activity assay confirmed the inhibitory effect of irbesartan on the enzymatic activity of DHCR24 with its half-maximal inhibitory concentration (IC50) value of 602 nM. Thus, to the best of our knowledge, this is the first study to report that blocking the enzymatic activity of DHCR24 via competitive inhibition is a potential strategy for developing new cholesterol-lowering drugs against hyperlipidemia or multiple cancers. Furthermore, considering that irbesartan is currently used to treat hypertension combined with type 2 diabetes, we believe that irbesartan should be a suitable choice for patients with both hypertension and hyperlipidemia.

Since the outbreak of the novel Corona Virus Disease 2019 (COVID-19) infected by SARS-CoV-2 at the end of 2019, clinical specific antiviral drugs have been lacking. A Chinese patent medicine called ‘Toujiequwen Granules’ has been promoted in the treatment of COVID-19. The present study was designed to reveal the molecular mechanism of Toujiequwen Granules against COVID-19. A network pharmacological method was applied to screen the main active ingredients of Tongjiequwen Granules. Network analysis of 149 active ingredients and 330 drug targets showed the most active ingredients interacting with many drug targets are quercetin., drug targets most affected by the active ingredients are PTGS2, PTGS1, and DPP4. Drug target disease enrichment analysis showed drug targets are significantly enriched in cardiovascular diseases, digestive tract diseases and so forth. An ‘active ingredient-target-disease’ network showed that 57 active ingredients from Toujiequwen Granules, interact with 15 key targets of coronary pneumonia. There are 53 ingredients that can act on DPP4, suggesting that DPP4 may become a potential new key target for the treatment of COVID-19. The GO analysis results showed that key targets were mainly enriched in the cellular response to lipopolysaccharide, cytokine activity and other functions. KEGG analysis showed they were mainly concentrated in viral protein interaction with cytokine and cytokine receptors endocrine resistance pathway, and others. These evidences suggest that Toujiequwen Granules might play an effective role through improving the symptoms of underlying diseases in patients with COVID-19 and multi-target interventions against multiple signaling pathways related to the pathogenesis of SARS-CoV-2.