a study of the influence of macrophages activation on its capacity to bind bacterial antigens using...
TRANSCRIPT
A Study of the Influence of Macrophages Activation on its Capacity to Bind
Bacterial Antigensusing Atomic Force Microscopy
Marta Targosz1,
Pawel Czuba1, Magdalena Strus3, Janusz Marcinkiewicz2, and Marek Szymonski1
1Institute of Physics, Jagiellonian University, 2Chair of Immunology, Jagiellonian University Medical College, 3Chair of Microbiology, Jagiellonian University Medical College,
„Probiotic bacteria enhancing the immune response. Studies have suggested that consumption of yogurt or milk that contains specific strains of Lactobacillus or supplements with Lactobacillus or Bifidobacterium may improve the natural immuneresponse. Further research is needed to confirm these early findingsand to best understand how the improved immune function may or may not help inwarding off infections.” (University of Maryland Medical Center http://www.umm.edu)
Our results can increase understanding of the role of probiotic bacteria in organisms and their positive influence on the protective function of immune cells,like macrophages.
Motivation for studies of the influence of probiotic bacteria
like Lactobacillus on the function of macrophages to bind bacterial antigens:
... are located in the outer part of bacterial walls
... have polymer structure
... cause inflammation
... trigger macrophage phagocytosis
Bacterial antigens
bacterial antigen
(endotoxin)
Bacterial antigens in our experiments
Lipopolysaccharides (LPS):
pathogenic bacteria
elicit inflammation
extracted from Escherichia coli
Exopolysaccharides (EPS)
probiotic bacteria
do not elicit inflammation
extracted from Lactobacillus
Macrophages
... play an important role in immunological system
... recognise pathogenic factors and kill them (in
phagocytosis process)
... have receptors on the membrane that recognize and
bind bacterial antigens.
Macrophage activation by bacterial antigen
After bindingbacterial antigens
Before bindingbacterial antigens
The activation of the macrophage is a consequence of binding bacterial antigen by receptors
5 m
Experimental set-up tip of the AFM modification and sample preparation
Force spectroscopy
force-distance curve
polymer extension
Specific interaction
Non-specific interaction
Specific interaction
Example of a force-distance curve
By analyzing the force-distance curves it is possible to directly measure the force needed to destroy a ligand-receptor bond (rupture force)
x 500
Probability of adhesion events
PA = Nwith adhesive jump / Ntotal
N – number of force-distance curves
Non-specific interaction
Results obtained for the EPS-activated macrophages
1. Modified system I: EPS-activated macrophages - LPS on the tip
2. Modified system II:Lactobacillus-activated macrophages – LPS on the tip
3. Reference systems: non-activated macrophages - LPS on the tip
PA = 0.58 / PA = 0.4 PA = 0.58 / PA = 0.46
EPS-activated macrophages – LPS on the tip
Lactobacillus-activated macrophages – LPS on the tip
EPS/Lactobacillus activated macrophages maintain or even increase their ability to bind LPS.
Results obtained for the LPS-activated macrophages
1. Modified system I: LPS-activated macrophages - EPS on the tip
2. Modified system II: E coli-activated macrophages - EPS on the tip
3. Reference systems: non-activated macrophages - EPS on the tip
LPS-activated macrophages – EPS on the tip
E. coli-activated macrophages – EPS on the tip
The activation of macrophages by both LPS molecules and bacteria E.coli decreases their ability to bind EPS
PA = 0.7 / PA = 0.22 PA = 0.7 / PA = 0.14
Conclusions
By using atomic force spectroscopy we were able to directly determine the changes in interactions between bacterial antigens and receptors after activation of macrophages.
LPS / Escherichia coli activated macrophages decrease their ability to bind EPS.
EPS / Lactobacillus activated macrophages maintain or even increase their ability to bind LPS. This may suggest that in vivo probiotic bacteriawill enhance the defence potential of local macrophages against pathogens expressing LPS.
These results are promising for improving the understanding of the role of probiotic bacteria in organisms and their interaction with immune cells, like macrophages (main motivation of this work)
Collaborations
Department of Immunology, Jagiellonian University Medical College
Department of Microbiology, Jagiellonian University Medical College
Institute of Immunology and Experimental Therapy, Polish Academy of Sciences,
This work was supported by the Grants: 1 P03B 098 28 and 3 T11E 033 26, from the Committee for Scientific Research (MNII) of Poland.
Atomic Force Microscopy (AFM)
liquid cell with sample
cantilever
piezo-scanner
detector
laser
•AFM provides three dimensional
images of biological specimens surfaces in ambient liquid and in gas environments
•AFM doesn’t require destructive methods of sample preparation,
such as coating or freezing
•AFM can probe elastic or adhesion
properties on surfaces by measurement of a so called
“force-distance curves”
Experimental set-up
PA = 0.58 PA = 0.12
Reference systems: non-activated macrophages - LPS on the tip
Receptor TLR4 is responsible for the bio-recognition of the LPS by macrophages.
PA = 0.7 PA = 0.37
Reference system: non-activated macrophages - EPS on the tip
The lack of significant changes in the average rupture force obtainedfor both systems suggest that TLR4 receptor doesn’t (or very weakly)contributed to the EPS binding.