Inflammation
VLA, October 17, 2017
Inflammation
 Inflammation is the response of living tissue to
damage. The acute inflammatory response has
3 main functions.
 The affected area is occupied by a transient
material called the acute inflammatory
exudate. The exudate carries proteins, fluid and
cells from local blood vessels into the damaged
area to mediate local defences.
 If an infective causative agent (e.g. bacteria) is
present in the damaged area, it can be
destroyed and eliminated by components of
the exudate.
 The damaged tissue can be broken down and
partialy liquefied, and the debris removed from
the site of damage.
Etiology
 The cause of acute inflammation may be
due to physical damage, chemical
substances, micro-organisms or other
agents.
 The inflammatory response consists of
changes in blood flow, increased
permeability of blood vessels and escape of
cells from the blood into the tissues. The
changes are essentially the same whatever
the cause and wherever the site.
 Acute inflammation is short-lasting, lasting
only a few days.
Inflammation
 In all these situations, the inflammatory
stimulus will be met by a series of changes in
the human body; it will induce production of
certain cytokines and hormones which in turn
will regulate haematopoiesis, protein
synthesis and metabolism.
 Most inflammatory stimuli are controlled by a
normal immune system. The human immune
system is divided into two parts which
constantly and closely collaborate - the
innate and the adaptive immune system.
Inflammation
 The innate system reacts promptly without
specificity and memory. Phagocytic cells are
important contributors in innate reactivity
together with enzymes, complement
activation and acute phase proteins.
 When phagocytic cells are activated, the
synthesis of different cytokines is triggered.
These cytokines are not only important in
regulation of the innate reaction, but also for
induction of the adaptive immune system.
There, specificity and memory are the two
main characteristics.
Inflammation
 In order to induce a strong adaptive immune
response, some lymphocytes must have been
educated to recognise the specific antigen
on the antigen-presenting cell (APC) in
context of self major histocompatibility
molecules. The initial recognition will mediate
a cellular immune reaction, production of
antigen-specific antibodies or a combination
of both. Some of the cells which have been
educated to recognise a specific antigen will
survive for a long time with the memory of the
specific antigen intact, rendering the host
"immune" to the antigen.
Differences between innate (non-specific) and specific
(adaptive) immunologic reaction of organism
 Non-specific Immunity
 Response is antigen-
independent
 There is immediate
maximal response
 Not antigen-specific
 Exposure results in no
immunologic memory
 Specific Immunity
 Response is antigen-
dependent
 There is a lag time
between exposure and
maximal response
 Antigen-specific
 Exposure results in
immunologic memory
Changes compared with
normal state
Increase Decrease
Cellular phagocytotic cells
(in circulation and at
the site of
inflammation)
erythrocytes
Metabolic acute phase proteins
serum Cu
protein catabolism
gluconeogenesis
serum Fe
serum Zn
albumin synthesis
transthyretin
transferrin
Endocrinological glucagon
insulin
ACTH
GH
T4
cortisol
aldosterone
vasopressin
T3
TSH
Gastroenterology. 2013 August;145(2):293-308.
Role of epigenetics in pathogenesis of diseases
13.12.2017 9
13.12.2017 10VKP 20. 2. 2015
13.12.2017 11
Epigenetic remodelling of chromatin and reprogramming od genes during
acute systemic inflammation.
13.12.2017 12
Leukoc Biol. Sep 2011; 90(3): 439–446.
Integration between bioenergetics and epigenetics during
acute systemic inflammation
13.12.2017 13
Leukoc Biol. Sep 2011; 90(3): 439–446.
Chronic inflammation
potentionally takes
part in all phases of
tumorigenesis
13.12.2017 14
Systemic manifestation of
inflammation
 1. Increase of body temperature
(fever)
 2. Acute phase reaction
Systemic effects of acute inflammation
 Pyrexia
Polymorphs and macrophages produce compounds known
as endogenous pyrogens which act on the hypothalamus to
set the thermoregulatory mechanisms at a higher
temperature. Release of endogenous pyrogen is stimulated
by phagocytosis, endotoxins and immune complexes.
 Constitutional symptoms
Constitutional symptoms include malaise, anorexia and
nausea. Weight loss is common when there is extensive
chronic inflammation.
 Local or systemic Iymph node enlargement commonly
accompanies inflammation, while splenomegaly is found in
certain specific infections (e.g. malaria, infectious
mononucleosis).
Systemic effects of acute inflammation
 Haematological changes
 Increased erythrocyte sedimentation rate. An increased erythrocyte
sedimentation rate is a non-specific finding in many types of
inflammation.
 Leukocytosis. Neutrophilia occurs in pyogenic infections and tissue
destruction; eosinophilia in allergic disorders and parasitic infection;
Iymphocytosis in chronic infection (e .g. tuberculosis), many viral
infections and in whooping cough; and monocytosis occurs in infectious
mononucleosis and certain bacterial infections (e.g. tuberculosis,
typhoid). Anaemia. This may result from blood-loss in the inflammatory
exudate (e.g. in ulcerative colitis), haemolysis (due to bacterial toxins),
and 'the anaemia of chronic disorders' due to toxic depression of the
bone marrow.
 Amyloidosis
 Longstanding chronic inflammation (for example, in rheumatoid arthritis,
tuberculosis and bronchiectasis), by elevating serum amyloid A protein
(SAA), may cause amyloid to be deposited in various tissues resulting in
secondary (reactive) amyloidosis
Macroscopic appearance of
acute inflammation
 The cardinal signs of acute inflammation are modified
according to the tissue involved and the type of agent
provoking the inflammation. Several descriptive terms are
used for the appearances.
 Serous inflammation.
 Catarrhal inflammation
 Fibrinous inflammation
 Haemorrhagic inflammation
 Suppurative (purulent) inflammation
 Membranous inflammation
 Pseudomembranous inflammation
 Necrotising (gangrenous) inflammation.
 can be caused by microbial agents such
as
 viruses, bacteria, fungi and parasites
 by non-infectious inflammatory stimuli, as
in rheumatoid arthritis and graft-versushost
disease
 by tissue necrosis as in cancer
 by burns and toxic influences caused by
drugs or radiation
Acute inflammation
Early Stages of Acute Inflammation
The acute inflammatory response
involves three processes:
 changes in vessel calibre
(=vasodilation) and, consequently,
slower blood flow
 increased vascular permeability and
formation of the fluid exudate
 formation of the cellular exudate by
emigration of the neutrophil
polymorphs into the extravascular
space.
Early Stages of Acute Inflammation
The steps involved in the acute inflammatory response are:
 Small blood vessels adjacent to the area of tissue damage
initially become dilated with increased blood flow, then
flow along them slows down.
 Endothelial cells swell and partially retract so that they no
longer form a completely intact internal lining.
 The vessels become leaky, permitting the passage of
water, salts, and some small proteins from the plasma into
the damaged area (exudation). One of the main proteins
to leak out is the small soluble molecule, fibrinogen.
 Circulating neutrophil polymorphs initially adhere to the
swollen endothelial cells (margination), then actively
migrate through the vessel basement membrane
(emigration), passing into the area of tissue damage.
 Later, small numbers of blood monocytes (macrophages)
migrate in a similar way, as do Iymphocytes.
The acute phase reaction
 In the acute phase reaction, several biochemical,
metabolic, hormonal and cellular changes take place in
order to fight the stimulus and re-establish a normal
functional state in the body.
 An increase in the number of granulocytes will increase the
phagocytotic capacity, an increase in scavengers will
potentiate the capability to neutralise free oxygen radicals,
and an increase in metabolic rate will increase the energy
available for cellular activities, despite a reduced food
intake.
 Some of these changes can explain the symptoms of an
acute phase reaction, which are typically fever, tiredness,
loss of appetite and general sickness, in addition to local
symptoms from the inducer of the acute phase.
General and local clinical symptoms of the acute phase
reaction
General symptoms Local symptoms
fever calor
increased heart rate rubor
hyperventilation dolor
tiredness tumor
loss of appetite functio laesa
Biochemistry and physiology of
the acute phase reaction
 The acute phase reaction is the body's first-line
inflammatory defence system, functioning without
specificity and memory, and in front of, and in parallel
with, the adaptive immune system.
 CRP is a major acute phase protein acting mainly
through Ca2+-dependent binding to, and clearance
of, different target molecules in microbes, cell debris
and cell nuclear material.
 In an acute phase reaction there may be a more than
1000-fold increase in the serum concentration of CRP.
CRP is regarded as an important member of the family
of acute phase proteins, having evolved almost
unchanged from primitive to advanced species.

Signální transdukce pro IL-6
The acute phase proteins
 Induction of the acute phase reaction means
changes in the synthesis of many proteins
which can be measured in plasma.
 Regulation of protein synthesis takes place at
the level of both transcription (DNA, RNA) and
translation to protein.
 The cells have intricate systems for up- and
down-regulation of protein synthesis, initiated
by a complex system of signals induced in the
acute phase reaction.
The acute phase proteins
Most of the proteins with increased serum concentrations
have functions which are easily related
 to limiting the negative effects of the acute phase stimulus
or
 to the repair of inflammatory induced damage.
Examples are enzyme inhibitors limiting the negative effect
of enzymes released from neutrophils, scavengers of free
oxygen radicals, increase in some transport proteins and
increased synthesis and activity of the cascade proteins such
as coagulation and complement factors. The synthesis may
be upregulated even if plasma levels are normal, due to
increased consumption of acute phase proteins.
Function Acute phase protein Increase up to
Protease inhibitors "1-antitrypsin
"1-antichymotrypsin
4 fold
6 fold
Coagulation proteins fibrinogen
prothrombin
factor VIII
plasminogen
8 fold
Complement factors C1s
C2b
C3, C4, C5
C9
C5b
2 fold
Transport proteins haptoglobin
haemopexin
ferritin
8 fold
2 fold
4 fold
Scavenger proteins ceruloplasmin 4 fold
Miscellaneous 1-acid glycoprotein
(orosomucoid)
serum amyloid A
protein
C-reactive protein
4 fold
1000 fold
1000 fold
CRP functions
 Most functions of CRP are easily understood in the context of the
body's defences against infective agents.
 The bacteria are opsonised by CRP and increased phagocytosis is
induced.
 CRP activates complement with the split product being
chemotactic, increasing the number of phagocytes at the site of
infection. Enzyme inhibitors protect surrounding tissue from the
damage of enzymes released from the phagocytes.
 CRP binds to chromatin from dead cells and to cell debris which
are cleared from the circulation by phagocytosis, either directly or
by binding to Fc-, C3b- or CRP-specific receptors. Platelet
aggregation is inhibited, decreasing the possibility of thrombosis.
 CRP binds to low density lipoprotein (LDL) and may clear LDL from
the site of atherosclerotic plaques by binding to cell surface
receptors on phagocytic cells.
Typical changes of CRP, fibrinogen, ESR (erythrocyte sedimentation
rate) and albumin during an acute phase reaction
Classical pathway activation
Alternative pathway of complement activation
Lectin pathway activation
Lytic pathway
 The lytic (membrane attack) pathway involves the C5-9
components. C5 convertase generated by the classical or
alternative pathway cleaves C5 into C5a and C5b. C5b
binds C6 and subsequently C7 to yield a hydrophobic
C5b67 complex which attaches quickly to the plasma
membrane. Subsequently, C8 binds to this complex and
causes the insertion of several C9 molecules. bind to this
complex and lead to formation of a hole in the membrane
resulting in cell lysis.
 The lysis of target cell by C5b6789 complex is nonenzymatic
and is believed to be due to a physical change in the
plasma membrane. C5b67 can bind indiscriminately to any
cell membrane leading to cell lysis. Such an indiscriminate
damage to by-standing cells is prevented by protein S
(vitronectin) which binds to C5b67 complex and blocks its
indiscriminate binding to cells other than the primary target
The lytic pathway
Biologically active products of complement
activation
 Chemotactic factors
C5a and MAC (membrane attack complex
C5b67) are both chemotactic. C5a is also a potent
activator of neutrophils, basophils and macrophages
and causes induction of adhesion molecules on
vascular endothelial cells.
 Opsonins
C3b and C4b in the surface of microorganisms
attach to C-receptor (CR1) on phagocytic cells and
promote phagocytosis.
 Other biologically active products of C activation
Degradation products of C3 (iC3b, C3d and C3e)
also bind to different cells by distinct receptors and
modulate their function.
Biologically active products of complement
activation
 Activation of complement results in the
production of several biologically active
molecules which contribute to resistance,
anaphylaxis and inflammation.
 Kinin production
C2b generated during the classical pathway of
C activation is a prokinin which becomes
biologically active following enzymatic
alteration by plasmin.
 Anaphylotoxins
C4a, C3a and C5a (in increasing order of
activity) are all anaphylotoxins which cause
basophil/mast cell degranulation and smooth
muscle contraction.
Chemotaxis
 is directed movement of cells in concentration
gradient of soluble extracellular components.
 Chemotaxis factors, chemotaxins or
chemoattractants
 Positive chemotaxis = cells move do the places
with higher concentrations of chemotactic
factors.
 Negative chemotaxis = cells move from the
places with higher conentrations of
chemotactioc factors
 Chemoinvasion = cells move through basal
membrane
Cytokines
 The term cytokine is used as a generic name for
a diverse group of soluble proteins and
peptides which act as humoral regulators at
nano- to picomolar concentrations and which,
either under normal or pathological conditions,
modulate the functional activities of individual
cells and tissues. These proteins also mediate
interactions between cells directly and regulate
processes taking place in the extracellular
environment.
Cytokine network
 This term essentially refers to the extremely complex
interactions of cytokines by which they induce or suppress
their own synthesis or that of other cytokines or their
receptors, and antagonize or synergise with each other in
many different and often redundant ways.
 These interactions often resemble Cytokine cascades with
one cytokine initially triggering the expression of one or
more other cytokines that, in turn, trigger the expression of
further factors and create complicated feedback
regulatory circuits.
 Mutually interdependent pleiotropic cytokines usually
interact with a variety of cells, tissues and organs and
produce various regulatory effects, both local and
systemic.
Cytokines and inflammation
Cytokines
 In many respects the biological activities of cytokines resemble
those of classical hormones produced in specialized glandular
tissues. Some cytokines also behave like classical hormones in
that they act at a systemic level, affecting, for example,
biological phenomena such as inflammation , systemic
inflammatory response syndrome , and acute phase reaction ,
wound healing , and the neuroimmune network .
 In general, cytokines act on a wider spectrum of target cells
than hormones. Perhaps the major feature distinguishing
cytokines from mediators regarded generally as hormones is
the fact that, unlike hormones, cytokines are not produced by
specialized cells which are organized in specialized glands, i. e.
there is not a single organ source for these mediators.
 The fact that cytokines are secreted proteins also means that
the sites of their expression does not necessarily predict the sites
at which they exert their biological function.
Chemokines
 New generic name given to a family of proinflammatory
activation-inducible cytokines.
These proteins are mainly chemotactic for
different cell types.
 All chemokines possess a number of conserved
cysteine residues involved in intramolecular
disulfide bond formation, which allows
chemokines to be grouped into families
according to the presence or absence of one
or more conserved cysteine residues.
Chemokines
 According to the chromosomal locations of individual genes two
different subfamilies of chemokines are distinguished.
 Members of the Alpha-Chemokines are referred to also as the 4q
chemokine family because the genes encoding members of this family
map to human chromosome 4q12-21. The first two cysteine residues of
members of this family are separated by a single amino acids and these
proteins, therefore, are called also CXC-Chemokines. Some members of
the subgroup of the human CXC-Chemokines are defined by the
conserved ELR sequence motif (glutamic acid-leucine-arginine)
immediately preceding the first cysteine residue near the amino-terminal
end. Chemokines with an ELR sequence motif have been found to
chemoattract and activate primarily neutrophils. Chemokines without the
ELR sequence motif appear to chemoattract and activate monocytes,
dendritic cells, T-cells, NK-cells, B-lymphocytes, basophils, and eosinophils.
 Members of the Beta-Chemokines or 17q chemokine family map to
human chromosome 17q11-32. The first two cysteine residues are
adjacent and, therefore, these proteins are called also CC-Chemokines.
Chemokines
 Members of the small group of
chemokines with a CXXXC cysteine
signature motif are referred to as DeltaChemokines
or CX3C-Chemokines or
CXXXC-Chemokines).
Chemokines
 The biological activities of chemokines are mediated by specific
receptors and also by receptors with overlapping ligand
specificities that bind several of these proteins, which always
belong either to the CC-Chemokines or the group of CXCChemokines.
Lymphocytes require stimulation to become
responsive to most known chemokines, and this process is linked
closely to chemokine receptor expression. Chemokine receptors
belong to the large group of G-protein-coupled seven
transmembrane domain receptors that contain seven
hydrophobic alpha-helical segments that transverse the
membrane.
 The receptors that bind CXC-Chemokines are designated CXCR
followed by a number (CXCR1, CXCR2, CXCR3, CXCR4, CXCR5,
CXCR6) while those binding CC-Chemokines are designated CCR
followed by a number (CCR1, CCR2, CCR3, CCR4, CCR5, CCR6,
CCR7, CCR8, CCR9, CCR10, CCR10A, CCR10B, CCR11). The "R"
nomenclature is used for receptors that bind chemokines and
elicit intracellular signaling in response to binding of a ligand.
Chemokines
 According to their mode of expression and
function, chemokines have been categorized
as inflammatory chemokines and homeostatic
chemokines.
 Inflammatory chemokines are expressed usually
by leukocytes or related cells only upon cell
activation. These factors mediate emigration of
leukocytes.
 Homeostatic chemokines are expressed
constitutively and are involved usually in
relocation of lymphocytes or other cell types.
 Dual-function chemokines can act as
inflammatory cytokines or homeostatic
cytokines.
Chemokines
 Erythrocytes through their promiscuous chemokine
receptor play an important role in regulating the
chemokine network. Chemokines bound to the receptor
on erythrocytes are known to be inaccessible to their
normal target cells. This appears to provide a sink for
superfluous chemokines and may serve to limit the systemic
effects of these mediators without disrupting localized
processes taking place at the site of inflammation.
 Many genes encoding chemokines are expressed strongly
during the course of a number of pathophysiological
processes including autoimmune diseases, cancer,
atherosclerosis, and chronic inflammatory diseases.
Inflammasomes
 Inflammasomes are multiprotein complexes.
 An inflammasome mainly consists of cytoplasmic sensor molecule,
such as NLRP3, the adaptor (apoptosis associated speck-like protein
containing caspase recruitment domain) protein along with effector
procaspase-1.
 The inflammasome regulates caspase-1 activation, resulting in
secretion of interleukin- 1β and interleukin-18. The inflammasome
activation is linked with infection, stress, or other immunological
signals involved in inflammation.
 The pathophysiological role of NLRP3 inflammasome in immune
regulation, inflammatory receptor-ligand interactions, microbialassociated
molecular patterns, danger as well as pathogen
associated molecular patterns has been demonstrated in last few
years.
 The role of the inflammasome in peripheral and central nervous
system involved with cytokine and chemokine inflammatory
responses has been demonstrated in preclinical and clinical studies.
Schematic of ubiquitin (Ub)modifying
enzymes and
ubiquitination events regulating
NLRP3 inflammasome activity.
In addition to upregulating NLRP3 and IL1β
mRNA, priming also leads to NLRP3
deubiquitination.
NLRP3 is modified by K48- and K63-linked Ub.
Phosphorylation of NLRP3 may be linked to its
ubiquitination status.
Prior to NLRP3 inflammasome assembly, ASC
gets phosphorylated and linearly ubiquitinated.
ASC can also undergo K63-linked ubiquitination
by TRAF3.
Pro-caspase-1 undergoes K63-linked
polyubiquitination by cIAP1, cIAP2, and TRAF2.
After NLRP3 inflammasome assembly, active
caspase-1 cleaves
pro-IL-1β to IL-1β. Pro-IL-1β undergoes K63linked
polyubiquitination and binds unanchored
Ub chains. A20 restricts polyubiquitination of
pro-IL-1β in a
RIPK3-dependent manner. T
he exact character and composition of
heterogeneous Ub chains in the inflammasome
are not well understood.
J Mol Biol. 2017 Oct 12. pii: S0022-2836(17)
30471-0. doi: 10.1016/j.jmb.2017.10.001
Schematic of NLRP3
inflammasome activation.
LPS signaling through TLR4 or other
priming signal activates NFκB and
upregulates NLRP3 and IL1β mRNA. A
second signal such as potassium efflux
then activates the inflammasome.
NLRP3, NEK7, ASC, and pro-caspase-1
assemble to form the NLRP3
inflammasome. This leads to
autoproteolytic cleavage of pro-caspase-
1 yielding active caspase-1. Active
caspase-1 cleaves pro-IL-1β to mature
IL-1β for release. Cleavage of pro-IL-18
into mature IL-18 is not pictured.
Caspase-1 can also cleave gasdermin D,
releasing the N-terminal fragment that
drives pyroptosis.
PYD, pyrin domain; NACHT, NAIP, CIITA,
HET-E, and TP1 domain; LRR, leucinerich
repeat domain; CARD, caspase
recruitment domain.
J Mol Biol. 2017 Oct 12. pii: S0022-2836(17)
30471-0. doi: 10.1016/j.jmb.2017.10.001
Thank you for your
attention