Download The Mechanosensitive TRPV4 Ion Channel

The Mechanosensitive TRPV4 Ion
Channel Mediates the
Pro-resolution/Anti-fibrotic
Macrophage Response to LPS
Rachel G. Scheraga, MD
Cleveland Clinic
Cleveland, OH
Bacterial pneumonia in
Idiopathic pulmonary fibrosis (IPF)
• Recurrent pneumonia in IPF patients
causes progressive decline in lung
function
• Infection-associated lung injury leads to
edema and inflammatory cell infiltration
causing increased matrix stiffness and
secretion of cytokines
Molyneaux et al. Am J Respir Crit Care Med, 2014
Murray et al. Nat Rev Immunol , 2001
Wynn et al. Nature, 2013
Macrophage phagocytosis
• Critical to lung host defense and lung
injury, repair, and fibrosis
• Requires orchestration of macrophage
surface receptors, the particle itself, and
extracellular matrix
Rougerie et al. Immunol. Rev, 2013
Wynn et al. Nature, 2013
Blakney et al. J Biomed Mater Res A, 2012
Transient receptor potential vanilloid 4
(TRPV4)
• Mechanosensitive cation-permeable channel that
is activated by chemical and physical stimuli,
including plasma membrane stretching
• Ubiquitous cell type and tissue expression
• Our lab is the first to investigate the significance
of TRPV4 in lung fibrosis
Montell et al. Cell, 2002; Everaerts et al; Prog Biophys Mol Biol, 2010
Hypothesis
TRPV4 integrates the extracellular
matrix stiffness and LPS signals to
mediate infection-associated lung
injury and repair
TRPV4 mediates macrophage
phagocytosis of IgG-coated beads
UT
LPS
400
*
300
*
200
si
R
H
C
N
O
K
TR
PV
4
T
W
A
100
0
TRPV4 KO-UT
*
4
WT-LPS
+
TR
PV
WT-UT
Fluorescence Intensity (AU)
500
TRPV4 KO-LPS
Scheraga et al. J Immunol, In press
TRPV4 mediates macrophage
phagocytosis of E. coli particles
AM
BMDM
80
C
H
N
4
PV
TR
TR
PV
si
4
R
K
T
O
40
A
60
*
80
60
40
O
100
100
K
120
4
*
*
120
TR
PV
*
140
T
160
UT
LPS
W
UT
LPS
Fluorescence Intensity (AU)
(Normalized to WT UT)
140
W
Fluorescence Intensity (AU)
(Normalized to WT UT)
180
+
+
Scheraga et al. J Immunol, In press
40
20
ss
G
la
kP
a
25
kP
a
8
kP
a
0
80
60
# #
# #
40
20
0
ss
60
100
G
la
+
120
WT-No HC (TRPV4 inhibitor)
TRPV4 KO-No HC
WT+HC
25
kP
a
80
Phagocytosis, % Induction by LPS
(Fluorescence Intensity per cell)
+
100
1
Phagocytosis, % Induction by LPS
(Fluorescence Intensity per cell)
The TRPV4-mediated phagocytic effect
depends on matrix stiffness
Scheraga et al. J Immunol, In press
**
200
150
100
50
0
WT
KO
LPS-stimulated IL-10
(% Increase above UT)
LPS-stimulated IL-1b
(% Increase above UT)
TRPV4 modulates an anti-inflammatory
cytokine profile in response to LPS
120
100
80
*
60
40
20
0
WT
KO
Scheraga et al. J Immunol, In press
TRPV4 mediates macrophage phagocytosis
of IgG-coated beads in live mice
Saline
LPS
WT
# beads/macrophage
20
KO
+
IT SALINE
IT LPS
15
10
*
5
0
WT
KO
Scheraga et al. J Immunol, In press
# Macs
# PMNs
# Lymph
400
*
300
*
200
100
Day 3
O
K
T
WT
TRPV4 KO
*
600
500
400
300
200
100
PV
4
W
TR
PV
4
W
K
T
O
0
700
Total protein (mg/mL)
[ g/ml]
500
TR
Absolute # BAL cells (x100/mL)
TRPV4 limits lung injury and initiates
resolution in a bacterial pneumonia model
Day 8
0
Day 3
Day 8
Conclusions
• These data suggest :
- TRPV4 mediates the
phagocytic and cytokine
profile response to
infection
- stiffness-dependent
manner
• May play a role in progressive
fibrosis seen in patients with
IPF after infection
Acknowledgements
Cleveland Clinic - Pathobiology
Dr. Mitchell Olman
Dr. Brian Southern
Dr. Lisa Grove
Susamma Abraham
Kathryn Niese
Cleveland Clinic - Immunology
Dr. Thomas Hamilton
Dr. Chenyang Zhao
Dr. Olman’s Lab
Questions?