E-Poster with pre-recorded video presentation Lorne Infection and Immunity 2021

The role of intracellular pattern recognition receptors in recognition and immunomodulation of dendritic cells in response to daptomycin resistant Staphylococcus aureus. (#273)

Nazneen Jahan 1 , Jhih-Hang Jiang 2 , Anton Y Peleg 2 3 , Meredith okeeffe 1
  1. Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
  2. Department of Microbiology, Monash University, Clayton, Victoria, Australia
  3. Department of Infectious Diseases, The Alfred Hospital , Clayton, Victoria, Australia

Methicillin resistant Staphylococcus aureus (MRSA)  infection is one of the leading causes of hospital-acquired infections and is more difficult to treat than other bacterial infections1. In recent years, resistance to last line anti-staphylococcal antibiotic daptomycin has been observed during treatment of MRSA bacteremia2. Protection against MRSA infection is challenging and requires both innate and adaptive immune effector mechanisms. Being at the interface between innate and adaptive immune responses, DCs are thus central to the immune protection against S. aureus. We have previously shown that distinct and paired clinical isolates of MRSA have differential capacity to induce DC activation, with MRSA strains resistant to the last‐line antibiotic daptomycin inducing a compromised response 3. However, this study explores the molecular mechanism by which MRSA strains impede DC activation, we explored the role of intracellular PRRs in the recognition and immunomodulation of these clinical isolates. We found that the cytosolic sensors cGAS and STING are implicated in the sensing of clinical isolates of MRSA, but their use is more prominent in response to Daptomycin sensitive (DapS) strains. We also determined that the TLR3 ligand poly(I:C) induced a highly synergistic increase in the activation of DC in response to both DapS and Daptomycin resistant (DapR) MRSA. Our work, thus provides important insights for the mechanism of differential recognition of clinical isolates of MRSA and immunomodulation through engagement of PRR pathways which are critical to achieve effective and comprehensive immune defense against this pathogen.

  1. 1. Naber, C.K. Staphylococcus aureus bacteremia: epidemiology, pathophysiology, and management strategies. Clin Infect Dis 48 Suppl 4, S231-237 (2009). 2. Marty, F.M. et al. Emergence of a clinical daptomycin-resistant Staphylococcus aureus isolate during treatment of methicillin-resistant Staphylococcus aureus bacteremia and osteomyelitis. J Clin Microbiol 44, 595-597 (2006). 3. Patton, T. et al. Daptomycin resistant Staphylococcus aureus clinical isolates are poorly sensed by dendritic cells. Immunology & Cell Biology 98 (2019).