Lymphocyte recirculation

1
Lymphocyte recirculation
2
The step model of leukocyte recruitment
sleeping cell
3
Adhesion molecules and activating factorsa)
mediate the different phases of leukocyte-
endothelial cell interaction
4
(No Transcript)
5
Adhesion molecules and activating factorsb)
act in combination to generate diversity in
leukocyte recruitment and immune response
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
Chemokines involved in rapid integrin activation

• CXC chemokines
• CXCL8 (IL-8, NAP-1)
• CXCL9 (Mig)
• CXCL10 (IP-10)
• CXCL12 (SDF1-a)
• CC chemokines
• -CCL2 (MCP-1)
• CCL11 ((Eotaxin)
• CCL17 (TARC)
• CCL19 (MIP3-b, ELC)
• CCL21 (6Ckine,SLC, exodus-2)
• CCL22 (MDC)

10
Modalities of rapid integrin activation by
chemokines
11
(No Transcript)
12
LFA-1
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
PI(3)K-dependent LFA-1 rapid lateral mobility is
not required to lymphocyte homing to secondary
lymphoid organs
17
(No Transcript)
18
Signaling to rapid adhesion triggering by
chemokines
19
RhoA mediates rapid integrin triggering by
chemokines
20
Which is the role of RhoA in different modalities
of LFA-1 triggering by chemokines?Is RhoA
involved in the regulation of in vivo lymphocyte
homing?
21
Tools to study RhoA function
- C3 convertase (exoenzyme C3) ---- gt
ADP-ribosylation on Asp41 - Transfection with
dominant positive or negative
- Not effector domain-selective - Not suitable to
study normal, primary, cells under
physiological conditions
22
Antennapedia homeodomain(60 aa)
Helix 2
Helix 3 (16 aa Penetratin-1) is responsible of
the translocation capability of the entire
protein.
Helix 3
Helix 1
23
Antennapedia-derived trojan peptides from the
effector regions of RhoA
24
RhoA trojan peptides inhibit stress fibers
induction by LPA
25
Effect of RhoA peptides on CCL21-induced naïve
lymphocyte rapid adhesion to low density ICAM-1
(500 sites/mm2)
26
Effect of RhoA peptides on CCL21-induced naïve
lymphocyte rapid adhesion to high density ICAM-1
(5000 sites/mm2)
27
Efficiency of plasma membrane translocation of
RhoA trojan peptides in lymphocytes
28
RhoA activation by CCL21(pull-down assay)
29
The 23-40 effector region of RhoA delivers
downstream signals controlling rapid LFA-1 high
affinity state induced by CCL21
30
23-40 and 92-119 effector regions of RhoA deliver
downstream signals controlling rapid LFA-1
clustering induced by CCL21
31
23-40 and 92-119 effector regions of RhoA deliver
signals controlling rapid LFA-1 clustering
induced by CCL21(statistical analysis)
32
MALT (Mucosal Associated Lymphoid Tissue)
33
RhoA-controlled LFA-1 high affinity state
mediates lymphocyte in vivo homing to Peyers
pathces
34
Distinct effector regions of RhoA differently
controls the complex modality of LFA-1 triggering
by chemokines
35
Acknowledgements
Cinzia GiagulliMatteo Bolomini-VittoriGabriela
ConstantinBarbara RossiLinda Ottoboni