Biology subjects

Azzopardi, K.

Publications and source records attributed to Azzopardi, K..

3 recordsLinked to original sources

bioRxiv2026

Streptococcus pyogenes transforms the salivary proteome during controlled human infection

Streptococcus pyogenes (Group A Streptococcus, GAS) is among the leading causes of infectious mortality and primarily manifests as acute pharyngitis. The development of an effective vaccine continues to be hindered by an incomplete understanding of the host immune response, particularly in the oropharynx. Here, we provided detailed insights into the dynamic salivary proteome during acute illness in a human clinical trial of controlled infection of 20 healthy adults (CHIVAS-M75 trial). Deep profiling of salivary proteins via mass spectrometry revealed a striking increase in pro-inflammatory plasma proteins such as alpha1-antitrypsin and elements of the complement system during peak infection as a clear indication of the acute phase response in the oral environment. Many of these proteins, such as fibrinogen, are well-defined targets of key streptococcal virulence factors, with others, such as vitronectin, suggested to play a role in the host-pathogen relationship. Several salivary proteins with known antimicrobial properties, such as mucin-7 and cystatin, decreased universally across the infected cohort. For the first time, we have described the local and immediate protein response to acute pharyngitis in the oral cavity, highlighting a general host inflammatory signature and an abundance of GAS virulence targets infiltrating to the site of infection.

molecular biology↗

bioRxiv2026

Characterisation and manufacture of a Neisseria gonorrhoeae challenge agent for use in an oropharyngeal controlled human infection model

BackgroundDespite the importance of oropharyngeal gonorrhoea in transmission, suboptimal antimicrobial responses and propensity for horizontal transfer of antimicrobial resistance at this site, it remains understudied. An oropharyngeal N. gonorrhoeae controlled human infection model (CHIM) represents a promising tool to study infection and undertake translational research. MethodsA panel of five contemporary N. gonorrhoeae isolates were subject to detailed characterisation to assess antimicrobial susceptibility, in vitro infectivity, cytotoxicity and serum sensitivity to inform challenge agent selection. A method for challenge agent manufacture, including release testing, was developed and validated. FindingsAll candidate isolates were able to infect the surface of pharyngeal and cervical cells in vitro. One isolate displayed an invasive phenotype, induced higher inflammatory cytokine production and displayed elevated serum resistance and was excluded. The remaining four isolates were minimally inflammatory, did not induce cytotoxicity and were susceptible to serum killing. Three of the four isolates grew in a defined liquid medium. Together these results led to the selection of a contemporary N. gonorrhoeae isolate suitable for use in CHIM. A challenge agent manufacture workflow was established and shown to reliably and reproducibly generate doses suitable for direct inoculation in an oropharyngeal CHIM. ConclusionPhenotypic characterization of candidate N. gonorrhoeae challenge agents led to the successful identification of a contemporary isolate suitable for implementation in a novel oropharyngeal gonorrhoea CHIM. We demonstrate the feasibility of a challenge inoculum manufacturing process that aligns with international best practice guidelines.

microbiology↗

bioRxiv2026

Attenuated interferon signalling in alveolar epithelium limits resistance to Streptococcus pyogenes

The upper respiratory tract is a primary niche for Streptococcus pyogenes colonisation and disease. Lower respiratory tract infection (pneumonia) is the most common invasive S. pyogenes syndrome. Studies have not previously examined how epithelial cells, from the airway to the alveolus, respond to S. pyogenes infection. Here, we established a scalable human in vitro model by differentiating induced pluripotent stem cells (iPSCs) into mature pseudostratified airway epithelium or alveolar type 2 epithelial cells, cultured at air-liquid interface and infected with S. pyogenes (M1UK and M75 strains). Both strains attached to iPSC-derived lung epithelial cells, with significantly greater adherence to the airway epithelium by M75 compared to M1UK. Moreover, invasion by both S. pyogenes strains of alveolar epithelial cells was greater than for the airway epithelium. Dynamic S. pyogenes gene expression changes were evident between 6 and 24 hours after infection, which was influenced by the infected cell type; however, virulence genes were not significantly altered. While infection of the airway epithelium induced rapid and dynamic inflammatory signalling, the alveolar epithelium demonstrated augmented cell death and mounted a transcriptional pro-inflammatory and proliferative response that was uncoupled from cytokine secretion. The airway epithelium model exhibited consistently higher baseline type I interferon (IFN) signalling than the alveolar epithelium. Invasion by S. pyogenes and inflammation was significantly reduced in IFN-{beta}-treated alveolar epithelial cells. In summary, we have established the first model of S. pyogenes infection in physiologically relevant airway and alveolar epithelial cells. Our findings suggest that host responses to infection are influenced by lung compartment, the S. pyogenes strain type, and infection timepoint, highlighting context-specific pathways that could be leveraged therapeutically.

microbiology↗