induction and function of the mucosal immune...
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Laboratory for Immunohistochemistry and Immunopathology (LIIPAT), Division of Pathology, Oslo
University Hospital, Rikshospitalet, Norway
Induction and function of themucosal immune system
• The MRKAd5 HIV-1 Gag/Pol/Nef candidate vaccine advanced to a phase 2b test-of-concept trial known as STEP, conducted by Merck & Co., Inc., and the HIV Vaccine Trials Network (HVTN).
• The vaccine neither prevented infection nor had an impact on early plasma virus levels in those who received the vaccine compared with the placebo recipients (2007).
• Additional studies with mucosal and biopsy specimens will be required to explore whether activation of cells at the mucosal sites were different between vaccine and placebo recipients.
Science 2008; 321: 530-2
Sandra Mazzoli et al. Nature Medicine 3:1250-57, 1997
HIV-specific mucosal and cellular immunity in HIV-seronegative partners of HIV-seropositive individuals
Most uninfected partners of couples discordant for HIV infection show evidence of HIV-specific secretory IgA at mucosal sites (vaginal wash)
Dimers are a girl’s best friendEditorial: Sarah Rowland-Jones:
The mucosae are an enormous battlefieldMucosal effector sites provide secretory IgA (SIgA) antibodies
Section through skin
Airways and oral cavity
Gastrointestinal mucosa
Hornified layerEpithelial cells
Mucus and cilia
GlandsPlasma cells
Surface epithelium
Glands (crypts)Plasma cells
Epithelial cells
IgAIgGNormal human colon
Plasma cellsH&E
IgA
80% of all plasma cells arelocated in gut mucosa
An adult exports 3 g of SIgA to the gut lumen per day
At the border of hell!
Local formation and export of mucosal immunoglobulins
Dimeric IgA (pIgA)
J chain
Mucus
Gland
IgA+J
SIgM
SIgA
IgM+J
LumenStroma
IgG
pIgR(mSC)
PentamericIgM IgG(±J)
Free SC
IgA+J
Plasma cells
IgA
IgA-coatedbacteria
Brandtzaeg Nature & J. Immunol. 1974; Brandtzaeg & Prydz Nature 1984
Ag‘The IgA pump’
Containment
Inductive site and effector site of gut immune system
Mod
ified
from
: Mac
Don
ald
& M
onte
leon
e S
cien
ce20
05;3
07:1
920-
25
(GALT)
Germinal center
B cell
Homing
Lamina propria
pIgR
Distantsites Normal effector site
SIgA
IgAIgG
Teff
Treg
pIgA
Lymphocyte
differentiation
Barrier function
Gut homing
IgA development
IgA export
Bug controlAntigen uptake
Immunoglobulin A (IgA) is the major antibody class in humans
Plasma cell
Secretory IgA (SIgA) with bound SC (the cleaved ectodomain of pIgR)
SC
Serum IgA(monomeric IgA)
Dimeric IgA (pIgA) with J chain (J)
IgA+J pIgA
J
?
m m m
p p p
IgA
Parotid gland
SC aff. Merge
Brandtzaeg P. Nature New Biol. 1973; 243: 142-43, Nature 1974; 252: 418-20, Mol. Immunol. 1983; 20: 941-66
pIgR
Free SC
Epithelialcell
SC (free or bound) exhibits several anti-microbial properties so the sacrificial pIgR might have originated from the innate defence system to drive the ‘IgA pump’
~40%
Plasma cell
SCIgA+J pIgA
J
? pIgR
Free SC
Epithelialcell
Immunoglobulin A (IgA) is the major antibody class in humansSecretory IgA (SIgA) with bound SC (the cleaved ectodomain of pIgR)
Serum IgA(monomeric IgA)
Dimeric IgA (pIgA) with J chain (J)
m m m
p p p
IgA
Parotid gland
SC aff. Merge
Brandtzaeg P. Nature New Biol. 1973; 243: 142-43, Nature 1974; 252: 418-20, Mol. Immunol. 1983; 20: 941-66
00
PP C-LP I-LP MLN PLN PT
Per
cent
age
J-ch
ain+
()
Per
cent
age
subc
lass
es (
)
100
80
60
40
2020
40
60
80
100
IgA+J
IgA2IgA1
Children
J-LP
Systemic antibodies: Mainly IgGMucosal antibodies: Mainly secretory IgA (SIgA)
MALT(NALT)
MALT(GALT)
Primary lymphoid organs
Secondary lymphoid
organs
Systemic and mucosa-associated lymphoid tissue (MALT)
F
F
FAE
Gut-associated lymphoid tissue (GALT)
GALT structures are strategically situated in relation to the greatest concentration of commensal bacteria (indigenous microbiota)
Peyer’s patches:distal ileum (nos. 100-250)Appendix: cecumIsolated lymphoid follicles (ILFs):distal large bowel (nos. ~ 30 000)
Maintenance of immune homeostasis in the human gut
IgA IgM
Oral tolerance(suppression)
Productive stimulation
Immune exclusion: SIgA/SIgM
IgE DTHIgG
Lymphoidfollicle
CD4
Other secretory effector tissues
Peyer's patch (GALT)
Peripheral blood
APC BT
TB
B
CD8
Thoracicduct
Mesentericlymphnode
TFDC CD4
MMM
M γ/δ
Ag
BpIgR/mSC
Mφ
CD4
Mucus
Endothelial gatekeeper function
Effector siteInductive site
IgA IgGM-cell area
FAE
GC
GC
Inductive site (GALT) Effector site (normal intestinal mucosa
M-cell area
Crypt
CD4CD8
CD20CD3
Maintenance of immune homeostasis in the human gut
IgA IgM
Oral tolerance(suppression)
Productive stimulation
Immune exclusion: SIgA/SIgM
IgE DTHIgG
Lymphoidfollicle
CD4
Other secretory effector tissues
Peyer's patch (GALT)
Peripheral blood
APC BT
TB
B
CD8
Thoracicduct
Mesentericlymphnode
TFDC CD4
MMM
M γ/δ
Ag
BpIgR/mSC
Mφ
CD4
Mucus
Endothelialgatekeeper function
Effector siteInductive site
FAE
MAdCAM-1
GCGC
GC
HEV
HEV
TAPC
M M M
B
Antigen
Effector site:normal gut mucosa
BT
IgA
SIgAB
MAdCAM-1
Mucosal leukocyte homing in the normal gut
Peripheral bloodEos.Mo PMN MC
FDC
MφAPC
Endothelial gate-keeper function
Mφ
α4β7+
Gut associated lymphoid tissue(GALT)
IgA IgG
pIgRPeyer’s patch
CCR10+
CCR9+MECTECK
Microvascular gut endothelium
Human NALT anlagen: prenatal (19 wks).Nasal ILFs in 40% < 2 yrs (inducible?).Rodent NALT: postnatal organogenesis.
Tonsils and adenoids are well designed for antigen trappingInductive sites
TALT
LALT
BALT
Peyer'spatches,appendixand solitary intestinal lymphoid follicles (GALT)
Tonsils &adenoids(NALT)
GC
Crypt
Human palatine tonsil
Scanning electron-microscopy (Owen, 1988)
Reticular cryptepithelium(cytokeratin)
43%
78%
Blood circulation
Mesentericlymph nodes
Inguinallymph nodes
Tonsils &adenoids
Cervicallymph nodes
Lacrimalgland
Bonemarrow
Peyer’spatches
63%
86%
60%
9%
67%43%
28%0%
Nasal &salivaryglands
33%60%
83% Gut
Cervixmucosa
40%
Integration and compartmentalization in the mucosal immune system
Duodenum
Colon
Freqency of various tissue samples with Cμ deletion, reflecting dissemination of sIgD+IgM– effector B cells from Waldeyer’s ring
(tonsils and adenoids) to systemic and mucosal immune compartments
Peyer’s patches
Mesenteric nodes
Inguinal nodes
Bone marrow
Cervical lymph nodes
Normal adenoids
Hyperplastic adenoids
Normal tonsils
Recurrent tonsillitis
IgA def.: tonsils& adenoids
Small bowel
IgA def.: duodenum
Salivary glands
Nasal mucosa
IgA def.:nasal mucosa
Lacrimal glands
IgA def.: lacrimal& salivary glands
IgA def.: colon
0 20 40 60 80 1000 20 40 60 80 100Percentage of positive samples Percentage of positive samples
n = 13
n = 9
n = 10
n = 5
n = 8
n = 6
n = 5
n = 7
n = 7
n = 2
n = 6
n = 8
n = 23
n = 22
n = 3
n = 26
n = 16
n = 3
Uterine endocervix n = 5
Large bowel n = 15
Compartmentalization of the integrated mucosal immune system
Femalegenitaltract
Peyer'spatches(GALT)
Tonsils andadenoids(NALT)
Lacrimal,nasal andsalivaryglands
BALT
Mammaryglands
Indu
ctiv
esi
tes
Effe
ctor
site
s
PNAd/VCAM-1MEC (CCL28)
Appendix and colonic-rectalisolated follicles(GALT)
Bronchi Small bowel
Large bowel
MAdCAM-1TECK (CCL25)
MAdCAM-1MEC (CCL28)
L-sel. (CD62L)CCR7α4β1
CCR10CCR9CCR10
α4β1α4β7
MEC (CCL28)
Shared homingmolecules (CCR10)
Johansen, Baekkevold, Carlsen, Farstad, Soler, Brandtzaeg, Blood 2005; 106:593-600
Systemic homing
The nature of secretory immunity in the female genital tract is obscure
• The most active SIgA system occurs in the gut, but secretory immunity also operates in the female genital tract; there are J chain-producing IgA+ plasma cells and pIgR/SC expression in the cervical mucosa and fallopian tubes
• The origin of these local IgA+ plasma cells remains partly undefined because organized inductive mucosa-associated lymphoid tissue (MALT) is generally absent from the genital tract
Role of the endometrium in secretory immunity
• Like cervical glandular epithelium, the endometrium can also perform pIgR-mediated external translocation of dimeric IgA
• These dimers appear to be mainly derived from serum, partly under hormonal regulation
• Paracellular diffusion of IgG and monomeric IgA through epithelia is also an important part of humoral immunity in the female genital tract
There is considerable local production as well as leakage of IgG into the female genital tract
• Human cervical mucosa often contains a substantial number of IgG-producing plasma cells
• It is possible that these plasma cells are derived from NALT or perhaps from the draining cervical lymph nodes
• Intranasal vaccination also appears to be quite efficient for systemic immunization, providing high-affinity serum IgG antibodies
Class distribution and J-chain expression of IgA- and IgG-producing plasma cells in human cervical mucosa
Imm
unoc
yte
clas
s di
strib
utio
n (%
)
0
IgA IgG IgM
20
40
60
80
100
J-ch
ain
expr
essi
on (%
)
IgA IgG0
20
40
60
80
100
Brandtzaeg and Johansen (unpublished)
IgA/IgG IgA + J chain IgG + J chain
IgA- and IgG-producing plasma cells with J-chain expression in cervical mucosa
IgA- and IgG-producing plasma cells with J-chain expression in duodenal mucosa
IgA + J chain IgG + J chain
Normal IgD:IgM:IgA:IgG:
82%62%51%2%
79%54%19%1%
Recurrent tonsillitis
82%55%29%36%
IgD:IgM:IgA:IgG:
50%63%2%
45%
IgA+J chain
Cryptepithelium
GC
IgA J chain
GC
GC
Tonsillar germinal centre (GC) and extrafollicular Ig-producing cells express J chain (% of total isotype)
Brandtzaeg & Korsrud Clin. Exp. Immunol. 1984; 58: 709-18
Tonsillar germinal centre contains IgG-producing plasmablasts which often show J-chain expression
IgG+J+
IgG J chain
IgAIgG
sIgM sIgDsIgM sIgA IgA+J
sIgD
sIgGsIgA
Extra-follicular compart-
ments
IgD
IgG
Tonsillargerminal centre
Founder cellMigration to distant secretory effector
sites
Mantle zone
J
J
J
J
JJJ
IgM+J
IgA + J chain
Lymphoidfollicle
GC
IgA J chain
Brandtzaeg Mol. Immunol. 1983; 20: 941-66
B-cell differentiation in germinal centres
The nasal route is attractive for mucosal vaccine administration
But be aware of direct communication between the olfactory bulb and CNS
Adenoids
Middle turbinate
Oral cavity
Tounge
Epiglottis
Inferior turbinate
Olfactory regionTubal tonsil
Palatine tonsil
Lingual tonsil
Skin
Waldeyer’s ringOrganized lymphoid tissue with M cells
Nasal anatomy and location of regional lymphoid tissue
Olfactory region
Ciliated mucosa
Nasal mucosaExtremely rich in dendritic cells
150-200 cm2
Jahnsen FL, Gran E, Haye R, Brandtzaeg P. Am J Respir Cell Mol Biol, 2004; 30:31-37
HLA-DRRFD-7
Human nasal mucosa
Effects of parenteral immunization with albumin on con-current penetration (2h) of human serum albumin (HSA) and transferrin (Trf) through rabbit sublingual mucosa
Bas
al c
onc.
x10
5 /api
cal
conc
. (30
mg/
ml)
Brandtzaeg & Tolo Nature 1977; 266: 262-63
HSA (69 kDa)Trf (90 kDa)
Naïve animals Immunized (IgG anti-HSA)
2
4
6
8
HSA
TrfHSA
Trf
IgG antibodies may increase mucosal permeability for bystander molecules
Confirmed in vivo (mice) that this complication is caused by IgG but not SIgA antibodiesLim & Rowley, 1982
• Mucosal vaccination offers several distinct advantages for protection of the female genital tract (SIgA balancing IgG antibodies)
• Nasal spray might be more acceptable than an intravaginal or rectal vaccine
• A combined nasal/vaginal/rectal approach would probably be most effective but perhaps socially less acceptable
Conclusions
AcknowledgementsLaboratory for Immunohistochemistry and Immunopathology
(LIIPAT) is part of Centre for Vaccinology and Immunotherapy (CEVI, 2001) and Centre of Excellence for Immune Regulation (CIR, 2007), funded by the Research Council of Norway, University of Oslo and Rikshospitalet
University Hospital
Marie Curie Training Network: CROSS-TALK(EC, 2008)