918. Infection with Staphylococcus aureus Alters Lipid Metabolism and Modulates Adipokine Secretion in Adipocytes
Session: Poster Abstract Session: Bacterial Pathogenesis
Saturday, October 22, 2011
Room: Poster Hall B1
Background: Fat tissue is an organ with endocrine and immunological properties whose functions go beyond simple energy storage. Additionally, metabolic diseases such as obesity and type 2 diabetes mellitus are associated with gram-positive infections and a worse clinical outcome. We hypothesize that adipocytes play an important role during systemic bacterial infections.

Methods: 3T3-L1 adipocytes were infected with Staphylococcus aureus (S. aureus) under normoglycemic and hyperglycemic conditions in the presence/absence of insulin. Intracellular presence and survival of S. aureus was investigated quantitatively and supernatant cytokine and adipokine concentrations were measured by ELISA. Lipid metabolism was investigated by Oil-red O staining, analysis of lipid droplet size, measurement of intracellular triglyceride and extracellular glycerol concentrations. Insulin receptor (IR) expression was analyzed by Western blot and IR signalling by Akt and MAPK phosphorylation. Additionally, adipose tissue gene expression and adipokine serum concentrations were studied in C57BL/6 mice infected with S. aureus intraperitoneally.

Results: Viable staphylococci could be demonstrated in adipocytes for up to 5 days. Intracellular persistence of S. aureus was glucose-dependent but not insulin-dependent and IR expression or IR signalling were not altered. Low bacterial inocula did not affect cell viability. Infection increased MCP-1, IL-6 and visfatin secretion whereas resistin and adiponectin were decreased. Infected adipocytes had higher intracellular triglyceride concentrations and larger lipid droplets due to a decreased lipolysis. Similarly, serum visfatin concentrations in S. aureus infected mice were increased whereas serum adiponectin concentrations were decreased.

Conclusion: The present study provides the proof that adipocytes are involved in inflammatory reactions to bacterial stimuli. Infection with S. aureus modulates adipokine secretion and lipid metabolism. These data provide a novel basis for a better understanding of infection-related metabolic disturbances.


Subject Category: B. Bacterial pathogenesis, studies in animal models, molecular pathogenicity

Frank Hanses, MD1, Andrea Kopp, PhD2, Bernd Salzberger, MD1 and Andreas Schäffler, MD2, (1)Dept. of Infectious Diseases, University Hospital Regensburg, Clinic for Internal Medicine I, Regensburg, Germany, (2)Dept. of Endocrinology, University Hospital Regensburg, Clinic for Internal Medicine I, Regensburg, Germany

Disclosures:

F. Hanses, None

A. Kopp, None

B. Salzberger, None

A. Schäffler, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.