Marco Rinaldo Oggioni, United Kingdom
University of Leicester Genetics and Genome BiologyAuthor Of 1 Presentation
CHARACTERISING THE EFFECTS OF CIRCADIAN RHYTHM ON SPLENIC MACROPHAGE CONTROL OF SYTEMIC INFECTION (ID 477)
Abstract
Background
It has been widely documented that an organism’s circadian rhythm can have a detrimental impact on its susceptibility to bacterial challenge and severity of infection. Previous literature has recorded significant differences in the survival time of mice following intraperitoneal infection at different times along the circadian cycle in experimental models of sepsis caused by Streptococcus pneumoniae, however the exact mechanisms behind this phenomenon are unknown. Following recent work in our group suggesting that the spleen is the major organ underpinning pneumococcal infection, we hypothesised that circadian-controlled processes within the spleen are responsible for inducing the differential survival times documented in vivo
Methods
We utilised in vivo experimental mouse models with intravenous infection occurring at opposite ends of the circadian cycle. Further, we performed quantitative analysis of bacterial numbers within organs recovered from these mice by utilising confocal laser scanning microscopy and quantitative pathology imaging.
Results
Here, we show that splenic bacterial burden, but not liver or blood counts, correlate with subsequent survival time. Further, intracellular bacterial foci vary in number and size specifically within a subset of splenic macrophages known as marginal zone metallophilic macrophages.
Conclusions
The survival time appears to be dependent on differential bacterial replication abilities specifically within marginal zone macrophages.