Aili Aierken

Bovine mastitis is a major infectious disease in dairy cattle, and the increasing prevalence of antimicrobial-resistant pathogens has created an urgent need for the development of effective antimicrobial agents. In this study, bovine enteric β-defensin (EBD) from Xinjiang Brown Cattle was cloned, expressed, and preliminarily evaluated for its antibacterial and protective effects against Enterococcus faecalis-induced mastitis. Bioinformatic analysis identified EBD as a secreted protein belonging to the bovine β-defensin family. The recombinant PCDH-EBD construct was successfully transfected into 293T cells, resulting in markedly increased EBD mRNA expression and detectable recombinant EBD protein expression, as confirmed by SDS-PAGE and Western blotting. In vitro agar diffusion assays showed that the EBD-containing preparation exhibited inhibitory activity against E. faecalis. In a murine mastitis model, EBD treatment significantly attenuated mammary histopathological lesions and reduced the expression of Mpo, Tnf, and Il6 compared with the mastitis group. 16S rRNA sequencing of mammary gland tissues showed that EBD treatment was associated with a reduced relative abundance of Enterococcus and partial restoration of microbial diversity. Transcriptomic analysis further revealed that EBD treatment was associated with alterations in NOD-like receptor signaling- and phagosome-related pathways, suggesting that these processes may contribute to its protective effects. Collectively, these findings indicate that enteric β-defensin EBD from Xinjiang Brown Cattle possesses antibacterial and anti-inflammatory potential, making it a candidate for developing antimicrobial agents against bovine mastitis.

Maintaining gut microbial homeostasis is crucial for host health, whereas infection with Escherichia coli (E. coli) is a major contributor to intestinal inflammation and microbial dysbiosis. Recent research has focused on probiotic strategies for managing enteric inflammatory disorders. Previous studies have shown that beneficial microorganisms show protection through modulating host immune responses, enhancing intestinal epithelial barrier integrity, and inhibiting pathogenic bacteria. To evaluate the prophylactic effectiveness of a recently isolated strain, Lacticaseibacillus casei 2S-1, in a murine model of E. coli-induced enteritis, this study focuses on interactions within the microbiota–intestinal–immune axis, together with host transcriptional responses and pathway enrichment associated with oxidative stress and mitochondrial function. In vitro analysis of probiotic features, including growth dynamics, acidogenic capacity, and tolerance to acidic and bile salt environments, as well as genetic safety profiling, followed the methodical isolation and taxonomic identification of L. casei 2S-1. A preventive intervention protocol was established, and a murine model of enteritis was induced by exposure to E. coli. Histopathological analyses were performed to observe in vivo safety and protective efficacy. Changes in gut microbial structure were characterized by 16S rRNA gene sequencing, while host responses were identified by intestinal immunohistochemistry and transcriptome profiling. L. casei 2S-1 showed probiotic properties. In vitro analyses showed that the strain exhibited tolerance to acidic and bile salt conditions, and its untreated culture supernatant showed antimicrobial activity against pathogenic bacteria. Its safety profile was supported by genomic analysis, which verified the lack of virulence-associated genes and antibiotic resistance factors. In vivo, L. casei 2S-1 pretreatment reduced mortality and intestinal inflammation, modulated gut microbial composition, and preserved intestinal barrier-associated protein expression in infected mice. This study provides experimental evidence supporting the prophylactic effects of L. casei 2S-1 and its associations with gut microbiota modulation and host transcriptional responses, providing a foundation for further investigation of probiotic-based preventive strategies against intestinal infections.

This study investigated the pathological processes by which two Salmonella strains induce orchitis and impair spermatogenesis in mice, with emphasis on inflammation and blood–testis barrier (BTB) integrity. Thirty male Kunming mice were randomly assigned to the human-derived Salmonella enterica serovar Enteritidis H71 group, the sheep-derived Salmonella enterica serovar Agona W42 group, or the phosphate-buffered saline control group (n = 10 per group). An acute orchitis model was established by intrascrotal injection. Histopathological examination revealed marked testicular and epididymal lesions, disruption of the spermatogenic epithelium, and reduced sperm abundance in infected mice. Transcriptomic analysis identified 4546 differentially expressed genes shared by the two infected groups and showed enrichment of the Toll-like receptor (TLR), nuclear factor kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) signaling pathways. Real-time quantitative PCR further showed increased expression of interleukin 6 (Il6), interleukin 1 beta (Il1b), and tumor necrosis factor (Tnf), accompanied by reduced expression of tight junction protein 1 (Tjp1), occludin (Ocln), and synaptonemal complex protein 3 (Sycp3) in infected mice (p < 0.05), except for Tjp1 in the W42 group. These findings indicate that Salmonella-induced inflammatory activation is associated with BTB disruption and impaired spermatogenesis, providing a basis for further investigation of bacterial orchitis and zoonotic reproductive risks.

Bovine mastitis is among the most prevalent and economically detrimental diseases in the dairy industry, with a high global incidence. Antimicrobial resistance among causative pathogens has become increasingly severe, while antibiotic therapy poses risks of drug residues and public health concerns. Enterococcus faecalis (E. faecalis), a major environmental pathogen associated with bovine mastitis, possesses strong intrinsic resistance and responds poorly to conventional antimicrobial interventions. Xinjiang Brown Cattle show inherent disease-resistance traits; however, the antimicrobial activity of their β-defensin EBD remains insufficiently characterized. This study aimed to clone the β-defensin EBD gene from Xinjiang Brown Cattle, evaluate its anti-E. faecalis activity in vitro and in vivo, and investigate the mechanisms underlying its protective effects against bovine mastitis, thus providing a potential candidate for antibiotic-free prevention and treatment. The EBD gene was successfully cloned and confirmed to encode a secreted cationic hydrophobic protein belonging to the bovine β-defensin family. The recombinant construct PCDH-EBD achieved efficient protein expression in 293T cells. In vitro antibacterial assays showed significant inhibitory activity of recombinant PCDH-EBD against E. faecalis. In a murine mastitis model, 16S rRNA high-throughput sequencing revealed that EBD administration reshaped the intestinal microbiota, significantly reducing the abundance of E. faecalis and other pathogens while increasing the abundance of beneficial bacteria such as Lactobacillus. Transcriptomic analysis further revealed that EBD attenuates mammary inflammation by regulating the NLR signaling pathway and enhances bactericidal activity via the phagosomal pathway. EBD reduced the expression of pro-inflammatory genes, including TNF-α, IL-6, and CCL12, and mitigated pathological damage in mammary tissue. EBD from Xinjiang Brown Cattle combines direct antibacterial and immunomodulatory activities, effectively alleviating E. faecalis-induced mammary inflammatory injury. These findings identify EBD as a promising alternative to antibiotics for the prevention and management of bovine mastitis and provide a scientific basis for developing disease-resistant germplasm resources in Xinjiang Brown Cattle.

The liver, as the largest metabolic and detoxification organ in mammals, metabolizes approximately 80–90% of drugs. However, drug-induced liver injury (DILI) is common and driven by factors such as individual variability, differences in liver metabolism, and improper drug use. Mesenchymal stem cells (MSCs), with their self-renewal and multipotent differentiation capabilities, offer therapeutic potential, but face challenges such as limited proliferation and increased apoptosis during in vitro expansion. Although MSCs exhibit low immunogenicity, they are often cleared by the host immune system, which limits their survival and engraftment. Glutathione peroxidase 3 (GPX3) is a key antioxidant enzyme that reduces reactive oxygen species (ROS), protecting cells from oxidative damage. CD47, also known as integrin-associated protein (IAP), helps cells evade immune clearance by binding to signal regulatory protein alpha (SIRPα) on the immune cells. Here, we used an acetaminophen (APAP)-induced DILI mouse model to evaluate the therapeutic efficacy of intravenously infused MSCs overexpressing GPX3 and CD47. Compared to unmodified MSCs, modified MSCs showed improved survival, reduced liver inflammation, and alleviated oxidative damage, offering enhanced protection against APAP-induced DILI.