Leukocyte extravasation | leukocyte adhesion and rolling
Summary
TLDRDieses Videotutorial aus der Reihe 'Shaman's Biology' konzentriert sich auf das Immunsystem und die Immunologie. Im fünften Teil der Serie werden Leukozyten-Rolling, Adhäsion und Freisetzung von Leukozyten aus Gefäßen in infizierte Gewebebereiche, ein Prozess namens Transendotheliale Migration, behandelt. Die Erklärung umfasst die Rolle von Makrophagen und Dendritischen Zellen, die als erste Verteidigungslinie gegen Pathogene dienen, sowie die Freisetzung von Interleukinen nach der Aufnahme von Bakterien. Die Interaktion dieser Interleukine mit den Leukozyten führt zur chemotaktischen Migration der Leukozyten durch die Endothelwand der Blutgefäße und schließlich in das infizierte Gewebe. Der Prozess besteht aus vier Phasen: Kontakt, Rolling, feste Anheftung und Migration. Dieser Mechanismus ist ein zentraler Bestandteil der angeborenen Immunantwort und fördert die Inflammation, die wiederum weitere Leukozyten in das infizierte Gewebe zieht.
Takeaways
- 🛡️ **Leukozyten-Rolling**: Leukozyten (Weißzellen) nutzen ein spezifisches Protein-Muster, um sich langsamer zu bewegen und von der Blutbahn aus auf das infizierte Gewebe aufzuschließen.
- 🔬 **Rolling-Mechanismus**: Die Interaktion zwischen Selektinen auf der Endothelzelle und Leukozyten ermöglicht ein langsames Rollen an der Gefäßwand.
- 🧬 **Leukozyten-Bindung**: LFA-1 (Leukozytenfunktionell Antigen 1) und ICAM-1 (Integrin-assoziiertes Zelladhesionsmolekül 1) interagieren, um das Leukozyten-Rolling zu stoppen und eine feste Bindung herzustellen.
- 🚑 **Chemotaxis**: Leukozyten migrieren in Richtung der höheren Konzentration von Chemokinen wie Interleukin 8, was als chemotaxis bezeichnet wird.
- 🏃 **Transendotheliale Migration**: Nach der festen Bindung durchqueren Leukozyten die Endothelzellschicht und migrieren in das infizierte Gewebe.
- 📈 **Inflammationsantwort**: Die Freisetzung von Interleukinen und anderen Zytokinen erhöht die lokale Konzentration und fördert die Migration von Leukozyten zur Infektionsstelle.
- 🔴 **Endothelzellen-Aktivierung**: Endothelzellen reagieren auf erhöhte Interleukinkonzentrationen, indem sie Selektine und Integrine auf ihrer Oberfläche exprimieren.
- 🤝 **Zell-Zell-Interaktion**: Die Interaktion zwischen Leukozyten und Endothelzellen ist entscheidend für den Eintritt der Leukozyten ins Gewebe.
- 🚨 **Pathogen-Erkennung**: Makrophagen und Dendritische Zellen erkennen Pathogenassoziierte molekulare Muster (PAMPs) und reagieren darauf, indem sie Phagozytose durchführen und Interleukine freisetzen.
- 🛤️ **Barriereüberwindung**: Leukozyten müssen die Blutgefäßwand überwinden, ohne sie zu beschädigen, um ins angrenzende Gewebe zu migrieren.
- 🔒 **Feste Bindung**: Die Interaktion von LFA-1 mit ICAM-1, verstärkt durch Interleukin 8, ermöglicht eine starke und dauerhafte Bindung der Leukozyten an die Endothelzellen.
Q & A
Was ist der Hauptinhalt des fünften Videos der Immunologie-Vorlesung?
-Das fünfte Video der Immunologie-Vorlesung konzentriert sich auf die Leukozytenrolle, die Adhäsion und die Freisetzung von Leukozyten aus dem Gefäß in das infizierte Gewebe, auch als liquide Sekretion bezeichnet.
Wie wird der Beginn der Infektion im menschlichen Körper hervorgerufen?
-Der Beginn einer Infektion wird normalerweise durch Verletzungen hervorgerufen, die bakterielle Eindringungen ermöglichen, wie im Video durch blaue farbige Strukturen dargestellt.
Welche Zellen sind für die Aufnahme von Bakterien in Geweben verantwortlich?
-Makrophagen und Dendritische Zellen sind für die Aufnahme von Bakterien in Geweben verantwortlich und sind Teil der ersten Verteidigungslinien des Körpers.
Was sind Interleukine und welche Rolle spielen sie im Immunsystem?
-Interleukine sind Teile der Chemokine-Moleküle, die von Makrophagen und Dendritischen Zellen freigesetzt werden, nachdem sie Bakterien aufgenommen haben. Sie spielen eine wichtige Rolle bei der chemotaktischen Bewegung von Leukozyten zum Infektionsherd.
Wie wird die chemotaktische Bewegung der Leukozyten beschrieben?
-Die chemotaktische Bewegung der Leukozyten ist ein Prozess, bei dem Leukozyten aufgrund einer erhöhten Konzentration von Interleukinen und Cytokinen aus den Blutgefäßen in das angrenzende infizierte Gewebe migrieren.
Was sind die vier Phasen des Prozesses der Leukozytenmigration aus den Blutgefäßen?
-Die vier Phasen sind: 1) Kontakt oder Haken, 2) Rollen, 3) Festhaften und 4) Migration des Leukozyten in das infizierte Gewebe.
Wie interagieren Selektine mit Leukozyten?
-Selektine sind Zelloberflächenmolekül, die von Endothelzellen exprimiert werden, wenn sie Interleukine spüren. Sie interagieren mit sialyl-Lewis-X-Molekülen auf der Leukozytenoberfläche und ermöglichen so den Kontakt und das Rollen der Leukozyten.
Welche Rolle spielen LFA-1 und ICAM-1 bei der Adhäsion von Leukozyten?
-LFA-1 (Leukozytenfunktionsassoziierte Antigenregulator 1) auf der Leukozytenoberfläche interagiert mit ICAM-1 (Integrin-assoziierte Zelladhäsionsmolekül 1) auf der Endothelzelloberfläche, was zur Stoppierung des Rollens und zur festen Adhäsion führt.
Wie wird die Transendotheliale Migration von Leukozyten beschrieben?
-Die Transendotheliale Migration ist der Prozess, bei dem Leukozyten durch die Endothelschicht der Blutgefäße in das umliegende Gewebe migrieren, ohne die Zellwand zu beschädigen.
Welche Faktoren erhöhen die Effektivität von Integrin-ICAM-1 Wechselwirkungen?
-Die Interaktion von LFA-1 mit ICAM-1 wird durch die Präsenz von Interleukin 8 auf der Endothelzelloberfläche und Interleukin-8-Rezeptoren auf der Leukozytenoberfläche verstärkt.
Was ist der Zweck der Leukozytenmigration in infizierte Gewebe?
-Der Zweck der Leukozytenmigration ist es, das infizierte Gewebe zu erreichen, um dort weitere Immunantworten zu unterstützen und den Körper vor Pathogenen zu schützen.
Wie hilft die Inflammation beim Leukozyten-Migrationsprozess?
-Die Inflammation fördert die Leukozytenmigration, indem sie die Konzentration von Interleukinen und anderen chemotaktischen Faktoren erhöht, die Leukozyten aus den Blutgefäßen in das infizierte Gewebe ziehen.
Outlines
😀 Grundlagen des Immunsystems und Leukozyten-Rolling
Dieser Absatz stellt die Grundlagen des Immunsystems und insbesondere des Leukozyten-Rollings vor. Es wird erklärt, wie Leukozyten von der Gefäßwand in das infizierte Gewebe migrieren. Der Prozess beginnt mit der Freisetzung von Interleukinen durch Makrophagen und Dendritische Zellen, die Bakterien aufnehmen (Phagozytose). Diese Interleukine erhöhen die Konzentration im Gewebe und lösen eine chemotaktische Bewegung der Leukozyten aus, die aus den Blutgefäßen in das angrenzende Gewebe migrieren. Der Prozess des Leukozyten-Rollings ist von großer Bedeutung für die Innate Immunantwort und die subsequente Aufnahme von Leukozyten in das infizierte Gewebe.
🏃 Leukozyten-Tethering und -Rolling
In diesem Absatz werden die drei Phasen des Leukozyten-Tethering und -Rollings erläutert. Zunächst erfolgt die Anheftung oder Kapselcheerung der Leukozyten an die Endothelzellen der Blutgefäßwand, was durch die Expression von Selectins und Sialyl-Lewis-X-Molekülen ermöglicht wird. Danach erfolgt das Rollen der Leukozyten langsam auf der Endothelzellschicht, was durch die Wechselwirkung von Selectins und Sialyl-Lewis-X vermittelt wird. Schließlich, nach dem Rollen, tritt eine starke Anheftung durch Interaktion von LFA-1 (Leukozyten) mit ICAM-1 (Endothelzellen) auf, die durch Interleukin-8 gestärkt wird und das vollständige Stoppen der Leukozyten ermöglicht.
🤝 Feste Anheftung und Extravasation von Leukozyten
Nachdem die Leukozyten rollen und fest angeheftet sind, tritt die sogenannte Extravasation auf, bei der Leukozyten durch die Endothelzellschicht migrieren. Dieser Prozess erfordert die Wechselwirkung von verschiedenen Integrins wie ICAM und VCAM mit ihren jeweiligen Liganden auf der Oberfläche der Leukozyten. Die Leukozyten ändern ihre Morphologie, indem sie Pseudopodien ausbilden, die es ihnen ermöglichen, sich durch die Endothelzellen zu bewegen, ohne diese zu beschädigen. Dieser Prozess ist Teil der zweiten Phase der Innate Immunantwort und ermöglicht es den Leukozyten, zum infizierten Gewebe zu migrieren, um das Entzündungsgeschehen zu verstärken.
📈 Chemotaxis und die Rolle von Interleukinen
Der vierte Absatz beschreibt den Prozess der Leukozyten-Migration und wie die Leukozyten durch das Gewebe gezwungen werden, sich im infizierten Bereich zu sammeln. Dies geschieht durch die chemotaktische Bewegung, bei der Leukozyten aufgrund der hohen Konzentration von Interleukinen im Gewebe angezogen werden. Die Ankunft der Leukozyten im Gewebe führt zur Zunahme der Interleukinkonzentration und zur Freisetzung von weiteren Inflammationsmediatoren wie Tumor-Nekrose-Faktoren. Dieser Zyklus verstärkt die Entzündungsreaktion und ist ein zentraler Bestandteil der Immunantwort gegen Infektionen.
Mindmap
Keywords
💡Leukocyte
💡Rolling
💡Adhäsion
💡Chemotaxis
💡Interleukine
💡Endothelzellen
💡Extravasation
💡Inflammation
💡Pathogen
💡Toll-like Receptors (TLR)
💡Integrine
Highlights
The video is part of an immunology lecture series focusing on the immune system.
Discusses leucocyte rolling, adhesion, and release from vessels into infected tissue.
Explains the importance of watching the series of videos for a comprehensive understanding.
Covers the initial defense mechanism involving innate immunity and inflammatory response.
Details the role of dendritic cells and neutrophils in engulfing bacteria through phagocytosis.
Interleukins are released by macrophages and dendritic cells after pathogen engulfment.
Interleukins act as chemoattractants for leukocytes, guiding them towards the site of infection.
Leukocytes move from blood vessels into infected tissue through a process called diapedesis.
Describes the four stages of leukocyte migration: tethering, rolling, firm adhesion, and transmigration.
Selectins on endothelial cells help leukocytes slow down and roll on the vessel wall.
Leukocyte rolling is facilitated by the interaction between selectins and sLe^X on leukocytes.
Integrins and LFA-1 on leukocytes interact with ICAM-1 on endothelial cells for firm adhesion.
Interleukin 8 stabilizes the binding of LFA-1 and ICAM-1, aiding in firm attachment.
Leukocyte transmigration through the endothelial cell layer is facilitated by additional integrins.
Leukocytes modify their shape with actin rearrangement and pseudopod production to migrate.
Chemotaxis guides leukocytes towards higher concentrations of interleukins at the infection site.
The process of leukocyte migration is crucial for the innate immune response and inflammation.
The video concludes with a call to like, share, subscribe, and continue watching the immunology series.
Transcripts
hello friends welcome to another video
tutorial from shamans biology we've been
talking about the immune system and
immunology lecture series and this is
the fifth video of the immunology
lecture and in this video we want to
talk about the leucocyte rolling
addition and release of leukocyte from
the vessel into the infected area of the
tissue which is liquid side extraversion
so we'll talk about these three things
together now remember as this is series
of videos it will be very beneficial for
you if you watch the previous video so
keep watching the videos as a series
because in the last video we talked
about the very first part of the defense
mechanism of our body which is the
integral part of innate immunity
involved with the inflammatory response
in the inflammation what happens
whenever there is a damage due to the
wound or something bacteria take entry
for example here we see the bacteria is
this blue colored things here so Mackel
is dendritic cells which are present
there in the tissue or let us say
neutrophils which can also be present in
the tissue
they will engulf those bacteria metrof
watch for example same as a phagocytosis
now after this engulfment it will also
start releasing certain factors okay
the factor is called interleukins
remember there are some molecular
patterns that are found in the bacteria
which is unique to them and this
macrophages dendritic cells which are
the prime cell so the first line of
cells against those those pathogens they
can find those pathogen associated
molecular patterns and using those
pathogen associated molecular patterns
this macrophages or dendritic cell they
can exactly sense the type of pathogen
that are entering into our body they can
sense it once the sense that pathogen
they start engulfing that pathogen
inside now this sense that pathogen with
the help of the presence
of different receptor molecules like
toll-like receptor TLR nada Regan we
talked about all these in details so
with the help of these things they can
recognize the presence of the pathogen
and then once they engulf the pathogen
they start releasing interleukins which
are the part of chemokines
molecules now the thing is once they are
releasing these interleukins which is
interleukin 1 interferon type 1
interleukin 8 and different types of
interleukins and also some other things
like histamines bloody kindness liquor
trains which are also secondary response
chemicals but these are the primary
response chemicals that are being
released in the infected tissue at the
start point of the infection
once this interleukins are released and
the cytokine is a release those things
are now filled there the concentration
of those in turn because let me change
the color let's take the green color for
the concentration so the concentration
of those interleukins are getting higher
and higher in the tissue side that thing
is acting as a chemical movement a
movement towards chemical that thing is
known as chemotaxis for the leukocytes
that are present in the blood vessel
okay so leukocytes are present in the
blood vessel it's rolling it's moving
through the blood vessels because the
blood is always circulating but once we
have high concentration of this in
cytokines like interleukin 1 interferons
this cytokine concentration is telling
this leukocytes to migrate towards
themselves that is known as a chemical
derived movement or chemotaxis so
leukocytes will move from the red blood
from these vessels into the infected
adjacent tissue area by the q axis
mechanism but there is a barrier that is
the endothelial wall of the blood vessel
you see the blood vessel wall though is
thinner but still there are cells
covering it it is a wall it's a physical
wall which these leukocytes needs to
evade to come the adjacent tissue it
cannot damage the wall because if itself
damage the wall that will be a bad thing
to do
so this is some way that cells will
migrate from this vessel into the tissue
that whole process we are going to talk
about right now and why this is
important because there are different
types of leukocytes you know all those
cells we know of T lymphocytes are there
which are different but the leukocytes
cell means your cinephile basophils
lymphocyte monocyte okay so all this
cells that we know of in this white
blood cells they are functional cells
and they are required for the helping
and the generation of some more unified
response against that pathogen that will
be known as awkward immunity one such
very important cell is neutrophil that
will be required in this area okay so in
this case they want those lymphocytes
they want all those lymphocyte cells now
before going into there they those
leukocytes cells are moving through this
blood stream and they are moving really
fast because the red blood cell is
moving and also they are moving with
themselves very very fast movement so
the first thing for taking them into
this tissue is that to slow them down
and finally stop them if you do not stop
somebody is running running like that
let us apparently this thing is running
and flowing I want to take this to my
side the first thing I should do is slow
it then stop it then take it so there
are three different stages will be there
first is the attachment or tethering of
the leucocyte into the endothelial wall
okay this is the attachment or T during
that is known as a cap cheering the
first thing capturing or tethering
second is the process called rolling
what tethering means there should be
some way this leukocytes cells will be
in contact with the endothelial cell
that is the attachment only
okay the first thing capture then we do
the rolling rolling means once we
capture those two things once we capture
the endothelial cell with the leukocytes
then we can start it rolling rolling
means is not moving and running it means
is it's just circulating it's just
rolling very very slowly then the third
part is the firm capturing or firm
attachment then going to be a proper
attachment but it will be not that
strong form very firm attachment over
there and then once the firm attachment
is done means after the end of the firm
attachment we can tell the leuco side is
now stopped then the fourth part
squeezing that leukocyte between the mm
endothelial cell this is the fourth
thing so there are four stages for the
whole process let me write those stages
here first is the contact second is
rolling the third one is firm attachment
and the fourth one is the migration of
the leucocyte into the infected tissue
these are the four stages if you break
them down for our convenience now for
this first thing of which is called
contact I told you no contact means the
leukocytes should be in direct
interaction with the endothelial cell
surface how they achieve this there are
specific proteins that leukocytes start
expressing so as now normally this
proteins are expressed in neutral
leukocytes all the time but these
endothelial cells start expressing only
when they sense this high concentration
of intelligence once this cells start
the sense of the interleukin
concentration going high the endothelial
cells start expressing a protein on the
surface of the cell which is known as
selecting okay now what is that let me
just draw simple thing this is let us
say the red blood this is the blood
vessel and these are let us say the
endothelial cells okay
and let us say this is the leucocyte
that we are talking about so the
leucocyte they are having a specific
carbohydrate moiety outside that is
known as signle lated EU is X this is a
carbohydrate structure known as silent
Lewis X molecules that will always
present there okay in the surface of
this leukocytes but the endothelial
cells do not have anything there so
normally when there is no infection
there is no interleukins
the leukocyte is moving very fast along
with the blood stream but now once there
is the presence of all those
interleukins and all those cytokines
interference and all those things the
concentration is going high in the
nearer tissue that influence this
endothelial cells to produce
selectins which is another cell surface
molecule so all these cells start
expressing another surface receptor
non-selective example of selecting is e
selecting P selecting okay with the help
of this selecting and selecting which
are present both side in the leukocytes
as well as so the Sally later lewis x
the function is selecting so it's just
like kind of looking like a hook that is
a hoop from the leuco side and the hoop
coming from the endothelial cell so once
they they create this hook so there can
be contact between leukocyte and this
surface receptor of selecting contact
could be made so as the process of
rolling rolling means slowing down a
little bit because now let us say two
types of selections that are present and
they are looking like hooks one from the
leuco side from from the endothelial
cells so as they are moving the hooks
are connecting again disconnecting
connecting and disconnecting so what is
going on they are not allowed to move
very fast but they can kind of a roll on
the surface of this selecting and the
interaction with the selecting and the
selected lewis x they can start kind of
roll look like a walking once first they
are flying they're running but now due
to the expression of this selecting we
make them to walk slowly let us known as
a rolling or leukocyte rolling so select
themes are not enough to completely slow
down but completely stop but it slows
down the movement a little bit after
some time when this getting kind of
rolling thing is going on
then this endothelial molecules and this
leukocytes both leukocytes also have
some other surface molecules known as
LFA one leukocyte rolling factor this is
called LFA one they have this LFA one on
their surface but this LFO one cannot
interact with selecting it
interact with another type of surface
receptor molecule known as integral
which is also being expressed by this
sense by this you endothelial cells so
now what we will see endothelial cells
start expressing this intervenes so once
they start expressing the integrins
which is drawn in the green color this
LFA one let's say this is the LFA one
and this is one example of integrins I
am one
so LFA one can interact with the I am
one which is present on the surface of
endothelium so this binding of LFA one
with the I cam one can actually stop the
movement and rolling of leukocytes okay
selecting interactions will slow down
leukocyte LFA 1 and I came 1
interactions we stopped the leukocytes
completely once the leukocyte rolling is
completely stopped now it is firmly
attached to some part of this
endothelial cell so it is now stopped
which is called the firm attachment so
for the firm attachment we need intake
greens for slowing down we need a
rolling we need silly things okay that
is the idea now again though they have
this LFA one from the beginning the
leukocytes and if they have even I can
but this interaction won't be that
strong if there is no Intel UK this LFA
one attachment with ikm one interaction
is not that strong usually but if there
is a presence of interleukin 8 in this
endothelial cells surface because they
they get this Intel
in this area and this showcase that on
the circus surface and then this
leukocyte have those interleukin 8
receptor so the binding of LFA 1 and I
came on gets much stabilized
once this leukocyte interacts with
interleukin 8 with the help of
interleukin 8 receptor so with the help
of this three range job binding finally
the interleukin can be stopped
okay integrins can do its job but the
integral functionality will be enhanced
in the presence of interleukin 8 okay
that thing will be done here
once the LICO side is rolling is done
and it's kind of a fixed in the area
then we need to do what is known as the
extra vision of this leukocyte so the
leucocyte migration from this
endothelial and actually through this
endothelial layer of the cells vascular
endothelial cell into the tissue which
is just in the attached proximity with
this blood vessel right and for this
fourth thing or migration they also need
the help of some integrins like I cam
peak M these are some other integrals
which help this process because you know
once it is interact and attached this
the junction between the two adjacent
cells they start they start actually
modifying their body the leukocytes
start modifying its body with the help
of acting rearrangement in acting fibers
acting fibers start to rearrange the
cell and start producing reports once
you produce pseudopods that can take
entry through this adjacent endothelial
vascular endothelial cells and this
leukocyte now can easily squeeze through
those two endothelial cells it is not
damaging it squeezing through the inner
space between these two cells into space
now as its squeezing through it it will
take some time for this whole process to
work but this squeezing is done because
they are moving the towards the
interleukin constant
which is high in this tissue compared to
the blood vessel through the process
called chemotaxis okay so that is how
the whole process of leukocyte rolling
addition and movement occur and this is
the second part of the innate immune
response because you know the first part
is the development of all those
interleukins in the first place movement
and migration of the cells to the place
causing inflammation inflammation in the
other hand drives this leukocytes to
come from the lead blood vessel into the
tissue infected tissue so that is the
second part and once this leukocytes
start coming there so they will see some
more cells start to gather in the
infected area so it will again further
rise the concentration of the other
interleukins interference even the
production of tumor necrosis factor
along with that they will start causing
more and more of a inflammatory response
because it will boost the inflammatory
response in further stream so that in a
sense is a process of leukocytes rolling
and adhesion and my tration I hope you
understand this video if you like this
video please hit the like button share
this video with your friends and
definitely subscribe to my channel to
get more videos like that and watch
through this whole series of immunology
video I hope it will help you thank you
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