Oral Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

Decoding neutrophil-bacterial interactions: a cross-omics exploration of the neutrophil response to M1T1 and M1UK Group A Streptococcus (118130)

Jarrad Pritchard 1 , Rachelle Balez 1 , Jan Schroeder 2 , Andrew Hayes 2 , Shane Ellis 1 , Mark Davies 2 , Ronald Sluyter 1 , Emma-Jayne Proctor 1 , Martina Sanderson-Smith 1
  1. School of Science and Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia
  2. The Peter Doherty Institute for Infection and Immunity and Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC, Australia

Group A Streptococcus (GAS), is a human-specific pathogen that can cause self-limiting infections, including pharyngitis and impetigo, as well as invasive pathologies such as necrotising fasciitis and streptococcal toxic shock syndrome. Neutrophils represent one of the most abundant immune cell in circulation and play a crucial role in the immune response during GAS infection. Previous research has demonstrated that GAS can alter neutrophil cellular pathways, including cell death and pro-inflammatory responses, however the neutrophil response to GAS still remains poorly characterised. Herein, we employed a sequential, cross-omics approach to characterise the human neutrophil response to globally disseminated emm1 lineages of GAS. Transcriptomics via bulk RNA sequencing following in vitro infection suggests that lipid metabolism and mitochondrial dysfunction are modulated in neutrophils, in response to emm1 GAS. Using a novel, single-cell mass spectrometry imaging protocol, we detect unique lipidomic fingerprints in neutrophils following GAS infection. We note the presence of phosphatidylcholine (PC) lipid classes associated with infection and sphingolipids associated with mock infection. Together, these fingerprints suggest activation of classical lipid synthesis pathways (i.e. the Kennedy pathway) and sphingolipid signalling of the NLRP3 inflammasome, which are poorly characterised during neutrophil activation by GAS. More specifically, upregulation of SPNS1, a lysophosphatidylcholine (LPC) transporter, poses a novel pathway for PC synthesis via recycling of lysosomal-derived LPC. These data point to previously unexplored, intracellular mechanisms that mediate the pro-inflammatory neutrophil response observed during GAS infection.