To analyze whether Cortex Eucommiae (CE) can inhibit pathological lung injury by regulating autophagy levels in chicks lung tissue and identify potential targets, thereby alleviating pneumonia damage caused by Haemophilus paragallinarum (Hp) infection. Experimental groups were established: Control group, Hp infection group, Hp+CE group, Hp+Rapamycin (Hp+Rapa) group, and HP+(NLR family, pyrin domain-containing 3, NLRP3) inhibitor (INF39) group. Assessments included: HE staining and pathological scoring of chick lungs, ELISA measurement of inflammatory cytokine expression, RT-PCR analysis of key autophagy genes and NLRP3/Caspase-1/IL-1β inflammatory pathway genes, Immunohistochemistry and Western blot analysis of autophagy protein (microtubule-associated protein 1 chain 3, LC3) and inflammatory proteins NLRP3, Caspase-1, and IL-1β. CE reduced pro-inflammatory cytokine secretion, inhibited NLRP3, Caspase-1, and IL-1β protein expression, and upregulated key autophagy genes and proteins, thereby promoting autophagy and subsequently alleviating Hp-induced pneumonia damage in chicks. CE alleviates Hp-induced acute lung injury in chickens by promoting autophagy and suppressing NLRP3 inflammasome expression. CE may represent a potential therapeutic agent for treating bacterial-induced acute lung injury.

The high-pathogenicity island (HPI) is a major virulence determinant in pathogenic Escherichia coli (E. coli), contributing to severe inflammation and tissue damage. Autophagy plays a critical role in clearing intracellular pathogens and modulating inflammation, but whether HPI manipulates this process remains unknown. Here, using a swine-pathogenic E. coli strain and its HPI-deficient mutant (Δirp2) generated by CRISPR/Cas9, we investigated the interplay between HPI and autophagy in RAW264.7 macrophages and a mouse intestinal infection model. We found that HPI⁺ infection induced autophagic activation, as evidenced by increased LC3 puncta (immunofluorescence), upregulated Beclin-1 and autophagy-related gene mRNA levels (qPCR), and downregulated phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) expression at both mRNA (qPCR) and protein (immunohistochemistry) levels. In a mouse model, HPI⁺ infection upregulated intestinal Microfold (M) cell markers and secretory Immunoglobulin A (IgA), triggered robust production of pro-inflammatory cytokines, and induced more severe tissue pathology than the HPI-deficient mutant. Pharmacological activation of autophagy with rapamycin alleviated HPI-induced inflammation and injury, whereas inhibition of autophagy by 3-methyladenine (3-MA) or Beclin-1 silencing exacerbated damage. These findings suggest that HPI induces autophagy, but the endogenous autophagic response is insufficient to counteract HPI-induced pathology; pharmacological enhancement of autophagy partially alleviated this insufficiency and reduced tissue damage. Notably, Beclin-1 knockdown blunted HPI-induced upregulation of PI3K and autophagy-related genes, suggesting a role for Beclin-1 in the transcriptional regulation of these responses. In conclusion, HPI simultaneously exerts direct pro-inflammatory effects and induces Beclin-1-dependent autophagy. Enhancing this autophagic response pharmacologically, rather than relying on the endogenous level triggered by HPI alone, limits excessive tissue damage. Thus, boosting autophagy may represent a promising therapeutic strategy against HPI-bearing pathogenic E. coli infections.