Effect of lipoteichoic acid purified from Lactobacillus rhamnosus GG on dendritic cells activation

ADRIAN FRIEDRICH; VALERIA CAMPO; MARIELA PAZ; JULIANA LEONI; DANIEL GONZÁLEZ MAGLIO

Congreso; LXII Reunión Anual Sociedad Argentina de Inmunología; 2014

Sociedad Argentina de Inmunología

Lipoteichoic acid (LTA) is a highly immunorreactive surface molecule found in Gram positive bacteria cell wall. It is involved in the development of sepsis, as well as in multiple organ dysfunctional syndrome, caused by these microorganisms. On the other hand, LTA purified from probiotic bacteria has shown to modulate the immune response in many animal models of different types of pathologies, like inflammatory bowel disease, cancer and allergy. In this context, our hypothesis is that one of the major cells that are modulated by LTA are Dendritic cells (DCs), increasing or decreasing the coestimulatory molecules expression. We used Bone Marrow-derived DCs (BMDCs) from SKH:1 mice to assess the effect of LTA purified from Lactobacillus rhamnosus GG (LGG) on DCs activation. There are many different protocols to differentiate BMDCs regarded to time of culture and concentration of GM-CSF that yield in different degrees of maturation and amounts of DCs. Therefore, we evaluated by Flow Citometry different culture times and GM-CSF concentration conditions to yield large quantities of immature DCs (iDCs), which could then be madurated by the addition of E. coli LPS (mDCs). We chose a 9 days culture period and the addition of 30% of J558 supernatant (GM-CSF source). This procedure yielded 70% CD11c+ cells. Futhermore, iDCs and mDCs were obtained as shown by: 23.2% CD80+CD40+, 30.6% MHC-II+CD80+ and 30.7% MHC-II+CD40+ that increased to 59,9% CD80+CD40+, 58.1% MHC-II+CD80+,  66.1% MHC-II+CD40+ upon stimulation with 1 ug/ml LPS for 24 hs. The stimulation of iDCs with 1 ug LTA from LGG showed a 1.5 fold decrease in CD40+ mean flurescence intensity (MFI) compared to unstimulated iDCs and 2 fold compared to mDCs. Then, we evaluated the expression of CD40 in mDCs pulsed for 4 hs with LTA from LGG. These cells decreased 1.3 fold in CD40+ MFI compared to mDCs. No differences were observed in CD80 or MHC-II. This work shows preliminarily that LTA from LGG could affect DCs activation by decreasing co-stimulatory molecules in order to modulate the immune response.