Development of a novel infection model to test CSF1-Fc as a potential therapeutic for early onset sepsis

Sepsis is a potentially fatal dysregulation of the host immune response to infection, involving stages of hyperinflammation that mediate organ damage and dysfunction. Early onset sepsis (EOS) is defined as onset within the first 72 hours after birth. It is caused by ingestion or inhalation of infected fluids either in utero or intrapartum. The only treatments currently available are antibiotics. However, with the rise in antibiotic resistance and long-term morbidities associated with antibiotic-induced dysbiosis, an alternative therapy is required. Our laboratory proposes colony stimulating factor-1 fusion protein (CSF1-Fc) as a potential host-based therapeutic, to clear the underlying infection and limit inflammation in EOS, as it has been shown to increase the maturity of macrophages. The aim of this project was to develop a novel neonatal infection model, to be utilised in future for the testing of potential therapeutics. This involved pipette-feeding bacteria to postnatal day 0 (P0) pups. Variations of this model involved administration of a mixed bacterial culture extracted from faeces that represents the maternal microbiome, or of a pure strain of Klebsiella pneumoniae to act as a clinically relevant model. Tested bacterial doses ranged from 104 – 108 colony forming units (CFU) over a 24, 48, 72 hour or 15 day infection duration. Bacterial colonisation was evaluated by plating the blood, spleen, small intestine and perianal swabs onto agar plates and counting colony forming units. Immune cell numbers were determined through haematoxylin and eosin (H&E) staining and anti-ionized calcium-binding adaptor molecule-1 (IBA1) immunohistochemistry of liver tissue sections. Contrary to our prediction, the faecal slurry and the selected strains of K. pneumoniae were unable to establish an infection and recover bacteria in a dose-dependent manner. Instead, increased virulence of the infecting agent, higher doses and a different infection timeline could be employed to improve success. Therefore, this thesis forms the basis for future investigations and informs on methodologies that require further optimisations, in order to achieve a dose-response neonatal infection model.

Grantor dc:publisher

The University of Edinburgh

Year dc:date.issued

2025

Author dc:creator

• Nicola Ann, Li

Advisors dc:contributor.advisor

• Pridans, Clare
• Picozzi, Kim

• early onset sepsis
• Sepsis
• factor-1 fusion protein (CSF1-Fc)
• colony forming units
• haematoxylin and eosin (H&E) staining
• α-ionized calcium-binding adaptor molecule-1 (IBA1)

Language dc:language.iso

en

Identifier URI

http://dx.doi.org/10.7488/era/5595

OAI identifier oai:identifier

oai:era.ed.ac.uk:1842/43048