SEST October 7th 2011 Slide 1 Louise Henningsen, PhD-student Dendritic cells serve their purpose in our immune system by eating and drinking -phagocytosis versus macropinocytosis and the effect on the immune response

SEST October 7th 2011 Slide 2 The immunologists on the 5th floor Hanne Frøkiær, Professor Stine Metzdorff, Assistent Professor Gudrun Weiss, post. doc. Kristina M. Udsen, PhD-student Dina S. M. Damlund, PhD-student Lisbeth Drozd Lund, PhD-student Mathilde B. Kristensen, PhD-student Anita Nalla, PhD-student Anni Mehlsen, Lab tech. Marianne K. Petersen, Lab tech. Sajeda Hamid Shaltagh, Lab tech. traninee Eva Fuglsang, M.Sc.-student Julie La Cour Karottki, B.Sc.-student Kasper....., B.Sc.-student

SEST October 7th 2011 Slide 3 Dendrites Fluorescent antibodies Confocal microscope = we can see the cells! Image by Julie La Cour Karottki Dendritic cells have dendrites The dendritic cell was discovered and described by Ralph M. Steinman in 1973 He receives this years Nobel Prize in Medicine. Sadly he passed away only a few days before the announcement 

SEST October 7th 2011 Slide 4 When put on a glass slide they try to eat it...and 2 movies

SEST October 7th 2011 Slide 5 What do they do? Dendritic cells patrol our bodies to see if there is anything we should activate our immune system against They are very important in regulating our immune system Dendritic cells in the intestine

SEST October 7th 2011 Slide 6 They activate our immune system if needed Martien L. Kapsenberg, Nature Reviews Immunology 3, (December 2003) 1. Recognition and internalisation 2. Interaction 3. Activation

SEST October 7th 2011 Slide 7 My interest: 1. Recognition and uptake Receptors on the surface of the cells recognise conserved structures on viruses, bacteria, etc.

SEST October 7th 2011 Slide 8 Illustration by: Julie la Cour Karottki Makropinocytosis = big gulp Phagocytosis = eating Then the cells eat and drink Specific Zipper-like mechanism Non-specific

SEST October 7th 2011 Slide 9 Makropinocytosis = big gulp Phagocytosis = eating Then the cells eat and drink Specific Zipper-like mechanism Non-specific Araki et al. Journal of Cell Science 116,

SEST October 7th 2011 Slide 10 Hypothesis Depending on the way bacteria is taken up by the dendritic cell, different immune responses are initiated

SEST October 7th 2011 Slide 11 Some stimuli trigger macropinocytosis Macropinocytosis is measured by the amount of small inert dextran particles the dendritic cells drink Laser Illustration by: Julie la Cour Karottki

SEST October 7th 2011 Slide 12 Some stimuli trigger macropinocytosis

SEST October 7th 2011 Slide 13 We can also see this in the microscope

SEST October 7th 2011 Slide 14 Now more on the immune response in the dendritic cells

SEST October 7th 2011 Slide 15 The central dogma of molecular biology TranscriptionTranslation DNA mRNA Protein

SEST October 7th 2011 Slide 16 When we stimulate a cell we get mRNA and protein Protein

SEST October 7th 2011 Slide 17 Kinetics in gene transcription Interferon-β is a central signaling molecule in viral immunity Lactobacillus acidophilus is a strong inducer of IFN-β Results: Gudrun Weiss

SEST October 7th 2011 Slide 18...until we activate macropinocytosis before adding the bacteria L. Acidophilus alone

SEST October 7th 2011 Slide 19 We can also measure the proteins produced Protein signaling molecules (cytokines and chemokines) are produced by the dendritic cells to tell the rest of the immune system to activate or down-regulate Proinflammatory cytokine L. Acidophilus alone

SEST October 7th 2011 Slide 20 Formation of signaling platforms To make the zipper-like movement many receptors are needed in close proximity to the bacterium Sphingolipids in the cell membrane (ceramide) can form rafts/domains Receptors can be concentrated in these domains Illustration by: Julie la Cour Karottki

SEST October 7th 2011 Slide 21 Hypothesis Zipper-like mechanism (phagocytosis)  A high receptor concentration which may allow signaling platforms and strong immune responses Example: Lactobacillus acidophilus is normally taken up by phagocytosis Illustration by: Julie la Cour Karottki

SEST October 7th 2011 Slide 22 Hypothesis cont.... If it it taken up by the macropinocytosis instead  no concentration of receptors needed  no signaling platforms are formed  only a weak IFN- β response Illustration by: Julie la Cour Karottki

SEST October 7th 2011 Slide 23 Image by Julie La Cour Karottki So this is where we’re at... Dendritic cells are very important for keeping a balance in our immune system To monitor what is present in our body they must eat and drink what they encounter and respond appropriately to alert and regulate the immune response There are different ways of eating and drinking, but we don’t really know what impact these different ways have But it looks like they may play a very important role!

SEST October 7th 2011 Slide 24 Thank you for your attention