Rat models of postintracerebral hemorrhage pneumonia induced by nasal inoculation with Klebsiella pneumoniae or intratracheal inoculation with LPS

• DOI: 10.3389/fimmu.2024.1477902
• Publication Date: 2025-01-08T05:11:35Z
• Authors: Ruihua Wang; Changlian Gan; Rui Mao; Yang Chen; Ru Yan; Geng Li; Tianqin Xiong; Jianwen Guo
• Keywords: Klebsiella pneumoniae; 16S rRNA sequencing and untargeted metabolomics; stroke-associated pneumonia; lipopolysaccharide; Immunology; Immunologic diseases. Allergy; RC581-607; intracerebral hemorrhage

A stable and reproducible experimental bacterial pneumonia model postintracerebral hemorrhage (ICH) is necessary to help investigating the pathogenesis novel treatments of Stroke-associated (SAP). To establish a Gram-negative pneumonia-complicating ICH rat an acute lung injury (ALI)-complicating model. We established two standardized models post-ICH by nasal inoculation with Klebsiella pneumoniae (Kp) or intratracheal lipopolysaccharide (LPS). Survival neurological scores were monitored. Magnetic resonance imaging was performed evaluate hematoma volume. Abdominal aortic blood collected for leukocyte counting, serum isolated determine concentrations S100β proinflammatory cytokines using ELISAs. Histopathological changes brain, gut assessed hematoxylin-eosin staining. Lung immunofluorescence staining myeloperoxidase (MPO). Bronchoalveolar lavage fluid supernatant prepared measure MPO activity. Ileum tight junction proteins ZO-1 γδ TCRs/IL-17A Alcian blue-nuclear fast red acidic mucins. Feces collected, 16S rRNA sequencing, untargeted metabolomics Spearman's correlation analyses explore microbiota, metabolites their interactions. In Kp-induced rats, we demonstrated that Kp challenge caused more severe deficits, brain damage, neuroinflammation, aggravated injury. Disruptions intestinal structure barrier reductions protective IL-17A-producing γδT cells also observed. exacerbated microbiota dysbiosis fecal metabolic profile disorders, which characterized abnormal sphingolipid metabolism especially elevated ceramide levels; increased levels neurotoxic quinolinic acid upregulation tryptophan (Trp)-serotonin-melatonin pathway. further revealed reduction depletion some beneficial bacteria, such as Allobaculum Faecalitalea, blooming opportunistic pathogens, Turicibacter, Dietzia, Corynebacterium Clostridium_sensu_stricto_1 in SAP rats associated disordered Trp metabolism. Using LPS-induced ALI complicating model, SAP-induced histopathology injuries; peripheral immune disorders intense pulmonary inflammatory responses. These may be highly useful screening optimizing potential SAP. Moreover, differential genera identified above seem promising therapeutic targets.