TH17 Cells Mediate Steroid-Resistant Airway Inflammation
and Airway Hyperresponsiveness in Mice1
Laura McKinley,* John F. Alcorn,* Alanna Peterson,* Rachel B. DuPont,* Shernaaz Kapadia,*
Alison Logar,* Adam Henry,†Charles G. Irvin,‡Jon D. Piganelli,* Anuradha Ray,†
and Jay K. Kolls2*
Steroid-resistant asthma comprises an important source of morbidity in patient populations. TH17 cells represent a distinct
population of CD4?Th cells that mediate neutrophilic inflammation and are characterized by the production of IL-17, IL-22, and
IL-6. To investigate the function of TH17 cells in the context of Ag-induced airway inflammation, we polarized naive CD4?T cells
from DO11.10 OVA-specific TCR-transgenic mice to a TH2 or TH17 phenotype by culturing in conditioned medium. In addition,
we also tested the steroid responsiveness of TH2 and TH17 cells. In vitro, TH17 cytokine responses were not sensitive to dexa-
methasone (DEX) treatment despite immunocytochemistry confirming glucocorticoid receptor translocation to the nucleus fol-
lowing treatment. Transfer of TH2 cells to mice challenged with OVA protein resulted in lymphocyte and eosinophil emigration
into the lung that was markedly reduced by DEX treatment, whereas TH17 transfer resulted in increased CXC chemokine
secretion and neutrophil influx that was not attenuated by DEX. Transfer of TH17 or TH2 cells was sufficient to induce airway
hyperresponsiveness (AHR) to methacholine. Interestingly, AHR was not attenuated by DEX in the TH17 group. These data
demonstrate that polarized Ag-specific T cells result in specific lung pathologies. Both TH2 and TH17 cells are able to induce AHR,
whereas TH17 cell-mediated airway inflammation and AHR are steroid resistant, indicating a potential role for TH17 cells in
steroid-resistant asthma. The Journal of Immunology, 2008, 181: 4089–4097.
IL-9, and IL-13 accompanied by eosinophil recruitment to the air-
ways has been considered integral to the pathogenesis of asthma.
Inflammatory cell recruitment to the lung results in tissue damage,
mucus hypersecretion, bronchoconstriction, and airway hyperre-
sponsiveness (AHR).3Glucocorticoid use attenuates airway eosin-
ophilia by inducing eosinophil apoptosis and inhibiting the re-
sponse to IL-5 and GM-CSF survival signals (1, 2). The broad
distribution of the glucocorticoid receptor in the airways suggests
there are multiple cell targets including not only inflammatory
cells, such as mast cells and the aforementioned eosinophil, but
epithelial and airway smooth muscle cells (3). Studies have shown
that 50% of asthma cases are noneosinophilic and in these cases
he CD4?Th cells are classified as TH1, TH2, and TH17
based on their cytokine expression profile. Classically, re-
cruitment of TH2 lymphocytes that secrete IL-4, IL-5,
CXCL8-mediated neutrophil inflammation in the airways is pre-
TH17 cells are a distinct population of CD4?T cells that secrete
IL-17A, IL-17F, and IL-22 (5, 6). The importance of TH17 cells in
neutrophilic inflammation lies in the ability of IL-17 to induce
granulopoiesis, neutrophil chemotaxis, and the antiapoptotic prop-
erties of G-CSF (7, 8). IL-17 is increased in the sputum of asth-
matic patients and correlates with CXCL8 levels and the number
of neutrophils in the sputum. PBMCs from both atopic and nona-
topic asthmatics secrete IL-17 in response to anti-CD3 and anti-
CD28 Ab stimulation (9). Apoptosis of neutrophils is inhibited by
glucocorticoids (10) and numerous studies have suggested non-
eosinophilic asthma is associated with poor response to cortico-
steroid treatment (11, 12). Based on this, we hypothesized that
TH17 cells mediate airway inflammation and hyperresponsiveness
associated with noneosinophilic asthma and are not responsive to
Models using adjuvant-induced Ag sensitization with alum have
shown that IL-17A and IL-17RA KO mice have reduced delayed-
type hypersensitivity reactions in tissue (13) and reduced priming
of TH2-immune responses in lung lymph nodes (Ref. 14 and our
unpublished observations). This may be due to the recently de-
scribed role of IL-17 in germinal center formation and setting up
chemokine gradients in lymph nodes (15). Thus, upon Ag chal-
lenge, IL-17RA KO mice have shown reduced recruitment of both
neutrophils and eosinophils into the airway (14). Whether this is
due to a role for IL-17RA in T cell priming in the lymph nodes or
in the effector phase after Ag challenge remains unclear (14).
Moreover it remains unclear from the studies published to date
whether TH17 cells in and of themselves mediate airway hyperre-
sponsiveness and goblet cell hyperplasia independent of Th1 or
TH2 cells. Based on these data, we used a model that had previ-
ously been used to study the effect of TH2 cells in inducing airway
inflammation and airway hyperresponsiveness utilizing adoptive
*Department of Pediatrics, Lung Immunology and Host Defense Laboratory and†De-
partment of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine,
University of Pittsburgh, Pittsburgh, PA 15213; and‡Department of Medicine, Ver-
mont Lung Center, University of Vermont, Burlington, VT 05405
Received for publication May 7, 2008. Accepted for publication July 20, 2008.
The costs of publication of this article were defrayed in part by the payment of page
charges. This article must therefore be hereby marked advertisement in accordance
with 18 U.S.C. Section 1734 solely to indicate this fact.
1This work was supported by National Heart, Ling, and Blood Institute Grant
R01HL079142 and National Institute of Allergy and Infectious Disease Grant
2Address correspondence and reprint requests to Dr. Jay K. Kolls, Children’s Hos-
pital of Pittsburgh, Suite 3765, 3705 Fifth Avenue, Pittsburgh, PA 15213. E-mail
3Abbreviations used in this paper: AHR, airway hyperresponsiveness; Ad, adenovi-
rus; BAL, bronchoalveolar lavage; DEX, dexamethasone; GR, glucocorticoid recep-
tor; i.t., intratracheal; LH, lung homogenate; KO, knockout; rm, recombinant mouse;
WT, wild type; PMN, polymorphonuclear neutrophil; PAS, periodic acid-Schiff.
Copyright © 2008 by The American Association of Immunologists, Inc. 0022-1767/08/$2.00
The Journal of Immunology
transfer of polarized T cell populations to SCID mice (16). SCID
mice were chosen to isolate the contribution of the transferred cells
as opposed to contaminating endogenous CD4?T cell popula-
tions. Additionally, this model does not use adjuvant priming in
vivo which has recently been questioned in terms of its relevance
to airway sensitization, which is what occurs in human allergen
Presently, we report that in vitro-polarized TH17 cells are non-
responsive to glucocorticoids. Adoptive transfer of these cells in a
model of Ag-induced airway inflammation resulted in increased
CXC chemokine secretion and G-CSF in the lung that was asso-
ciated with neutrophil influx to the airways. Treatment of TH17
cell reconstituted mice with dexamethasone (DEX) did not alter
airway inflammation but did attenuate TH2-induced airway inflam-
mation. Reconstitution of mice with either TH2 or TH17 cells re-
sulted in increased AHR to methacholine challenge. Surprisingly,
DEX treatment significantly reduced AHR in mice that received
TH2 cells but not in TH17-reconstituted animals. These data dem-
onstrate the significance of TH17 cellular responses in airway dis-
ease and implicate these cells as having a role in steroid-resistant
Materials and Methods
Six- to 8-wk-old, male BALB/c mice and SCID mice were purchased from
The National Cancer Institute. C.DO11.10 TCR-transgenic mice were ob-
tained from The Jackson Laboratory. IL-17R null mice have been previ-
ously described (17). All animals were housed in a pathogen-free environ-
ment and given food and water ad libitum. All experiments were approved
by the Children’s Hospital of Pittsburgh Animal Research and Care
Abs and reagents
Cell culture. Recombinant mouse (rm) IL-2, rmIL-4, rmIL-6, rmIL-23,
porcine TGF-?, anti-mouse IL-4 (clone 30340.11), and anti-mouse IFN-?
(clone 37895) were purchased from R&D Systems.
Immunofluorescence. Rabbit anti-mouse glucocorticoid receptor (GR; Af-
finity BioReagents) and goat anti-rabbit IgG conjugated to Alexa Fluor 555
(Invitrogen) were used.
Western blot. Polyclonal rabbit anti-mouse GR (Affinity BioReagents),
mouse monoclonal IgG1 anti-chicken ?-actin (Santa Cruz Biotechnology),
goat anti-rabbit IgG conjugated to alkaline phosphatase (AP; Bio-Rad), and
goat anti-mouse IgG conjugated to AP (Santa Cruz Biotechnology)
In vitro differentiation of Th cell subsets
CD4?T cells from the spleens and lymph nodes of C.DO11.10 TCR-
transgenic mice were enriched by negative selection using magnetic beads
(Miltenyi Biotec). CD4?CD62L?CD25?cells were sorted on a FACSAria
(BD Biosciences); purity was consistently ?99%. Cells were cultured with
irradiated APCs pulsed with OVA peptide 323–339 (OVA323–339) under
polarizing conditions as previously reported (18). Briefly, medium was
supplemented with 20 U/ml IL-2, 5 ng/ml rmIL-4, and 10 ?g/ml anti-
IFN-? (for TH2 polarization), or 10 ng/ml rmIL-23, 1 ng/ml TGF-?, 20
ng/ml rmIL-6, 10 ?g/ml anti-IL-4, and anti-IFN-? (for TH17 polarization).
Cultures were split 1:2 on day 3 and harvested on day 6. The total number
of cells was determined by counting on a hemocytometer; viable cells were
defined by trypan blue exclusion. APCs alone were CD4negor CD4dimand
proliferating CD4?T cells were CD4brightand stained positively with
KJ1-26 (eBioscience) and anti-Do11.01 TCR Ab. CD4brightcells were se-
lected for immunohistochemistry studies.
In vitro assays
To confirm the phenotype of the Th cell subsets, cells were stimulated with
in vitro with PMA/ionomycin for ELISPOT assays (R&D Systems) or
anti-CD3/anti-CD28-coated microbeads (Dynal) for cytokine assays.
Where indicated, cells were pretreated with increasing doses of DEX (Sicor
Pharmaceuticals) for 2 h before the addition of microbeads. After 36 h in
culture, cell supernatants were collected and stored at ?80° until analysis.
To measure NFAT activity of polarized T cells, primary culture mouse T
cells (1 ? 106/1.5 ml) were transfected with 4 ?g of NFAT-luciferase
plasmid (gift from S. Gaffen, State University of New York, Buffalo, NY)
and 1 ?g of SV40-Renilla. Transfection was conducted with the Mouse T
Cell Nucleofector Kit (Amaxa Biosystems) using the X-005 program on
the Nucleofector II instrument (Amaxa Biosystems). Following transfec-
tion, T cells were cultured for 18 h and were then treated with or without
1 ?M DEX for 2 h before treatment with anti-CD3/anti-CD28-coated
Dynabeads (Invitrogen Dynal) for 6 h at 37oC. After stimulation, luciferase
activity was determined using the Dual-luciferase Reporter Assay System
(Promega). NFAT-luciferase levels were normalized to SV40-Renilla as an
internal transfection control.
Superfrost Plus Micro Slides (VWR International) of 100,000 cells CD4?
cells (selected by Miltenyi beads) were fixed in 100% ice-cold methanol
for 10 min. Slides were stained with rabbit anti-mouse GR and visualized
with goat anti-rabbit IgG conjugated to Alexa Fluor 555 (Invitrogen) as
previously described (19). Accumulation of GR in the nucleus was ob-
served by epifluorescence illumination with a Zeiss Axioplan 2 microscope
equipped with a ?63, 1.4 aperture oil immersion objective. Quantitation of
fluorescence was performed by analyzing regions of interests (drawn over
the 4?,6-diamidino-2-phenylindole nuclear signal) of 100 cells captured
with a charge-coupled device camera (Intelligent Imaging Innovations) and
relative intensity values were determined and averaged with SlideBook
software (Intelligent Imaging Innovations).
Western blot analysis
Nuclear and cytoplasmic protein fractions were extracted from differenti-
ated T cells after DEX treatment using the Nuclear Extract Kit (Active
Motif) according to the manufacturer’s instructions. Protein concentration
was determined using a BCA Protein Assay Kit (Pierce Biotechnology).
AP development was visualized by the AP Conjugate Substrate Kit (Bio-
Rad) according to the manufacturer’s instructions.
Adoptive transfer model
BALB/c SCID mice were challenged with OVA protein (50 ?g/mouse,
intratracheal (i.t.); Sigma-Aldrich) on day ?1. On day 0, 1 ? 106differ-
entiated Th cells were adoptively transferred by retro-orbital injection.
Mice were challenged with OVA for 3 consecutive days after cell transfer
(50 ?g/mouse/day, i.t.). Animals were sacrificed 24 h after the last airway
challenge. Where indicated, mice were treated with 2.5 mg/kg DEX or PBS
control 2 h before cell transfer on day 0 and before OVA challenge on day
2. In separate experiments, wild-type (WT) BALB/c mice and IL-17R null
mice on a BALB/c background underwent the same adoptive transfer and
OVA challenge protocol.
Bronchoalveolar lavage (BAL) fluid and lung tissue collection
Lungs were lavaged with five 1-ml volumes of calcium- and magnesium-
free PBS. The supernatant from the first 1-ml aliquot was stored at ?80°C
for later analysis. Cell pellets from both aliquots were pooled in 1 ml and
total white blood cells in BAL fluid were counted using a particle counter
(Z1; Beckman Coulter). Cytospins of 100,000 cells were prepared using a
Shandon Cytospin 4 (Thermo Electron), slides were stained with HEMA 3
(Fisher Scientific), and differentials were quantified by counting 100 cells.
Lungs were harvested following the collection of lavage fluid. The right
lungs were homogenized in 1 ml of PBS containing 0.05% Triton X-100
and Complete Protease Inhibitor (Roche). Homogenate was centrifuged at
12,000 ? g for 15 min and supernatant was stored at ?80°C for later
Cell supernatants, BAL fluid, and lung homogenate (LH) samples were
analyzed for protein levels of G-CSF, IL-4, IL-5, IL-6, IL-13, IL-17,
IFN-?, and KC using a Luminex multiplex suspension cytokine array
(Linco) according to the manufacturer’s instructions. The data were ana-
lyzed using Bio-Plex Manager software (Bio-Rad). IL-22 was measured
using a commercial ELISA (R&D Systems) following instructions pro-
vided by the manufacturer.
Overexpression of IL-4 and IL-17 in the lungs
Adenovirus expressing IL-4, IL-17, or luciferase as a control was given at
108PFU i.t. on day 0 and AHR was determined 72 h later. Overexpression
of IL-4, IL-13, and IL-17 was determined by Luminex in both the BAL
fluid and LH of recipient mice.
4090TH17 CELLS AND AIRWAY INFLAMMATION
Determination of AHR
Airway responsiveness to methacholine challenge was determined on day
4 as previously described using anesthetized, intubated mice connected to
a computer-controlled small-animal mechanical ventilator (flexiVent; SCI-
REQ) (20). Airway resistance values (Rn) were calculated in response to
progressive concentrations of methacholine administered by i.v. injection.
Data are reported as mean ? SEM. GraphPad Prism version 4.0 was used
to calculate p values using one-way ANOVA with a Tukey multiple com-
parison posttest. A value of p ? 0.05 was considered statistically
TH17 cells are resistant to DEX treatment in vitro
Studies have shown that glucocorticoids inhibit the production of
IL-4, IL-5, and IL-13 from TH2 cells (21). To test the sensitivity of
TH17 cells to glucocorticoids, naive CD4?T cells from DO11.10
TCR-transgenic mice were differentiated in the presence of IL-6,
IL-23, TGF-?, anti-IL-4, and anti-IFN-? (18). As a positive con-
trol, naive CD4?T cells were polarized toward a TH2 phenotype
by conditioning with IL-2, IL-4, and anti-IFN-?. After 6 days in
culture, polarization was confirmed by PMA/ionomycin stimula-
tion and ELISPOT analysis (Fig. 1, A and B) and secreted cytokine
analysis (Fig. 1, C–F). Only TH17 cells produced IL-17 (Fig. 1A),
whereas in TH2 conditions the precursor frequency of IL-4-pro-
ducing T cells was 5.6-fold greater in TH2 cells compared with T
cells grown in TH17 conditions (Fig. 1B). Cells were also har-
vested on day 6 and treated with increasing doses of DEX for 2 h
before stimulation with anti-CD3/anti-CD28-coated microbeads.
As expected, TH2 cells secreted IL-4 (data not shown), IL-5, and
IL-13 (Fig. 1, C and D) following CD3/CD28 stimulation and
TH17 cells secreted high levels of IL-17 and IL-22 (Fig. 1, E
and F). Although both IL-5 and IL-13 generation from TH2
cells were inhibited at all doses of DEX studied, TH17 cell
cytokine production was not sensitive to DEX treatment at any
dose tested. Apoptosis was analyzed by annexin V and 7-ami-
noactinomycin D staining and ?85% of the TH2 and TH17 cells
were annexin V and 7-aminoactinomycin negative (viable) after
1 ?M DEX treatment (data not shown).
DEX treatment inhibits Ag-specific TH2-mediated airway
inflammation but not TH17-mediated airway inflammation in an
adoptive transfer model
To determine the Ag-specific immune response elicited by effector
TH17 cells in vivo, an adoptive transfer model of airway Ag-in-
duced inflammation was used (Fig. 2A). In vitro-polarized THcell
subsets were transferred i.v. to SCID mice on a BALB/c back-
ground that had been challenged with OVA protein i.t. 1 day be-
fore cell transfer to promote cell migration to the airways (16).
Following cell transfer, mice were challenged with OVA i.t. for 3
consecutive days and sacrificed on day 4, 24 h after the last OVA
challenge. Mice were treated with DEX (2.5 mg/kg) or PBS con-
trol by i.p. injection 2h before cell transfer on day 0 and again 2 h
before OVA challenge on day 2. Control mice reconstituted with
TH2 cells that were challenged with OVA had increased levels of
IL-5 and IL-13 in LH (Fig. 2, B and C). Mice transferred TH2 cells
without OVA challenge or scid mice challenged with OVA with-
out T cell transfer had LH levels of IL-5 and IL-13 that were ?50
sitive to DEX treatment in vitro.
CD4?CD62L?CD25?naive T cells
isolated from DO11.10 OVA TCR-
transgenic mice were cultured with WT
BALB/c splenocytes that had been
pulsed with OVA323–339under polariz-
ing conditions. On day 6, cells were
collected and stimulated with PMA/
ionomycin for precursor frequency by
ELISPOT or pretreated for 2 h with the
indicated doses of DEX before stimula-
tion with CD3/CD28 beads ? IL-2. A,
Spot frequencies of IL-17-producing T
ing T cells. Cells were plated under the
following conditions: T cells indicate un-
stimulated T cells cultured without bead
stimulation; 1 ?M DEX indicates T cells
pretreated with 1 ?M DEX but not stim-
ulated with CD3/CD28 microbeads;
beads indicates untreated T cells stimu-
lated with CD3/CD28 microbeads; ?M
DEX ? bead indicates T cells pretreated
ulated with CD3/CD28 microbeads. Cell
culture supernatant was collected at 36 h
after stimulation and the levels of TH2
and TH17 cytokines were determined by
multiplex suspension array assay. C,
IL-5 levels from TH2 cells. D, IL-13
levels from TH2 cells. E, IL-17 levels
from TH17 cells. F, IL-22 levels from
TH17 cells. All data are graphed as
TH17 cells are not sen-
4091 The Journal of Immunology
pg/ml (data not shown). Treatment with DEX significantly inhib-
ited the lung levels of IL-5 and IL-13 (Fig. 2, B and C). Groups
reconstituted with TH17 cells showed an increase in IL-17, G-CSF,
and the mouse homolog of CXCL8 KC in LH that was not ob-
served in mice receiving TH2 cells (Fig. 2, D–F). Mice transferred
TH17 cells without OVA challenge or scid mice challenged with
OVA without T cell transfer had LH levels of IL-17 and G-CSF
that were ?100 pg/ml; KC levels were ?500 pg/ml in these con-
trol mice (data not shown). Concurrent with the in vitro glucocor-
ticoid resistance, DEX treatment did not attenuate the TH17-in-
duced inflammatory cytokine response; in fact, there was a trend
toward increased levels of KC in the LH of DEX-treated TH17-
reconstituted mice compared with the TH17 PBS control.
Transfer of either TH2 or TH17 cells resulted in specific cellular
influx into the airways. We initially assessed lymphocyte recruit-
ment into the lung 24 h after adoptive transfer. Both transfer
of TH2 cells and TH17 cells resulted in 0.15 ? 0.06 ? 106and
0.18 ? 0.07 ? 106CD3/CD4?cells in BAL (p ? NS). However,
after three challenges with OVA, differential counting of BAL
fluid cytospins showed that TH2 reconstitution resulted in airway
inflammation consisting of both eosinophils and lymphocytes and
to a lesser extent polymorphonuclear neutrophils (Fig. 3, A–C).
Mice transferred TH2 cells without OVA challenge or scid mice
challenged with OVA without T cell transfer had BAL eosin-
ophil counts that were ?0.1 ? 106/ml (data not shown). The
influx of lymphocytes and eosinophils was highly sensitive to
DEX (Fig. 3, A and B), whereas the small numbers of polymor-
phonuclear neutrophils in the BAL were not inhibited by DEX
treatment (Fig. 3C). As expected, TH17 transfer resulted in a
primarily neutrophilic airway response (Fig. 3C). Mice trans-
ferred TH17 cells without OVA challenge or scid mice chal-
lenged with OVA without T cell transfer had BAL neutrophil
counts that were ?0.2 ? 106/ml (data not shown). In contrast to
mice receiving TH2 cells, DEX treatment exacerbated airway
neutrophilia in TH17-reconstituted mice.
To determine whether the airway responses of reconstituted
mice were mediated by IL-17 per se or another product of TH17
cells, we adoptively transferred TH17 cells into IL-17R KO mice
on a BALB/c background were challenged with OVA protein (50 ?g/mouse) i.t. on day ?1. On day 0, mice were pretreated with DEX (2.5 mg/kg, i.p.)
or PBS control 2 h before cell transfer (1 ? 106in vitro-polarized THcells). Mice were subsequently challenged with 50 ?g/mouse OVA for 3 consecutive
days. Animals were pretreated with DEX on day 2, 2 h before challenge. Mice were sacrificed on day 4, 24 h after the last airway challenge. Cytokine and
chemokine levels in the BAL fluid (data not shown, unless indicated) and LH (B–E) were determined by multiplex suspension cytokine array. Data are
graphed as mean ? SEM for n ? 4–8; ?, p ? 0.05 TH2_PBS vs TH2_DEX.
In vivo cytokine and chemokine profiles induced by TH17 cell transfer and allergen provocation are not attenuated by DEX. A, SCID mice
4092TH17 CELLS AND AIRWAY INFLAMMATION
on a BALB/c background and challenged them with OVA 1 day
before and for 3 consecutive days after cell transfer as before (Fig.
2A). IL-17R KO mice had significantly attenuated KC, G-CSF, and
IL-6 responses compared with WT BALB/c controls (Fig. 4, A–C).
Consistent with the decrease in CXC chemokine production in
IL-17R KO mice, there was a significant decrease in the number of
neutrophils in the airways (Fig. 4D). Again, there was not a sig-
nificant increase in eosinophil recruitment to the lung in either WT
or IL-17R KO mice transferred TH17 cells and challenged with
OVA (Fig. 4E). These data indicate that the inflammatory cytokine
response and cellular influx associated with TH17 cell transfer in
this model system is mediated primarily by IL-17 signaling
through the IL-17R.
Ag-induced AHR following adoptive transfer of TH17 cells is
not attenuated by DEX treatment
Having established the airway inflammation induced by TH17 cell
transfer, we wanted to determine whether TH17 cells are sufficient
to induce mucus hyperplasia and AHR at a level comparable to
way inflammation and AHR. BAL fluid dif-
ferential was determined by counting at least
100,000 cells. Data for A, lymphocytes; B,
eosinophils; C, neutrophils; and D, macro-
phages are graphed as mean ? SEM per-
centage of total cells for n ? 4–6; ?, p ?
0.05 PBS vs DEX in same transfer group; #,
p ? 0.05 TH2_PBS vs TH17_PBS.
TH2- and TH17-mediated air-
BALB/c controls that had been challenged with OVA 1 day before transfer. Mice were challenged with 50 ?g of OVA per mouse for 3 consecutive days
after transfer. BAL fluid differential and LH levels of cytokines and chemokines 24 h after the last airway challenge were determined. Levels of KC (A),
G-CSF (B), and IL-6 (C) in the LH were determined by multiplex suspension cytokine array. BAL fluid neutrophils (D), and eosinophils (E) are expressed
as cells/ml ? 106. Data are graphed as mean ? SEM for n ? 4–6; ?, p ? 0.05 compared with WT control.
The inflammatory response associated with TH17 cell transfer is mediated by IL-17. TH17 cells were transferred to IL-17R KO mice and
4093 The Journal of Immunology
that observed following transfer of TH2 cells. A significant hall-
mark of allergic airway disease is mucus hyperplasia; to address
this, LH expression of gob5 was determined by real-time PCR.
Data are normalized to control mice that had been challenged with
OVA on days ?1, 1, 2, and 3 but received a mock PBS transfer on
day 0. TH2 transfer resulted in a marked significant increase in
gob5 gene expression in the lung (Fig. 5A), which was decreased
in the DEX treatment group (Fig. 5B). Expression of gob5 in TH17
cell transfer groups was also significantly elevated over mock-
transferred animals (200-fold increase compared with OVA-chal-
lenged mice without cell transfer) but was ?10-fold lower than
that of the TH2 transfer groups (Fig. 5A). However, compared with
the TH2 transfer groups, DEX treatment had no effect on gob5
gene expression in the TH17 cell transfer group. Expression of
gob5 was confirmed by periodic acid-Schiff (PAS) staining of lung
sections; Fig. 5B is representative sections from TH2 and TH17 cell
recipient animals treated with PBS or DEX, respectively. Both
TH2 and TH17 transfer groups exhibit positive PAS staining in
airway epithelial cells.
To date, there are no data to demonstrate whether TH17 cells
are sufficient to induce AHR. IL-17 levels in the sputum cor-
relate with AHR to methacholine in asthmatic and chronic bron-
chitis patients (11). To determine whether IL-17 was sufficient
to induce AHR, an adenovirus (Ad) overexpressing IL-17
(AdIL-17) was administered i.t. to WT BALB/c mice and AHR
to methacholine was measured 72 h later. As controls, separate
normalized to the housekeeping gene 18S. Data are graphed as mean ? SEM for n ? 4; ?, p ? 0.05 vs TH2_PBS. B, Expression data were confirmed by
PAS staining of lung sections from TH2, and TH17, transferred animals. C, An adenovirus overexpressing IL-4, IL-17, or luciferase control was given i.t.
to WT BALB/c (108PFU/mouse) and airway responsiveness to methacholine was determine on day 3. ?, p ? 0.05 AdIL-4 vs Adluc; ?, p ? 0.5 AdIL-17
vs Adluc. D, Methacholine dose-response curves in control, TH2 vehicle-treated, or TH2 DEX-treated mice. Control mice received all OVA challenges but
PBS i.v. at time of cell transfer to experimental groups. Data are graphed as mean ? SEM for n ? 6–8; ?, p ? 0.05 for TH2 vs TH2 ? DEX. E,
Methacholine dose-response curves in control, TH17 vehicle- treated, or TH17 ? DEX-treated mice. Control mice received all OVA challenges but PBS
i.v. at time of cell transfer to experimental groups. Data are graphed as mean ? SEM for n ? 6–8.
IL-17 is sufficient to induce mucus secretion and AHR. A, gob5 expression was determined in whole lung by quantitative real-time PCR and
4094TH17 CELLS AND AIRWAY INFLAMMATION
groups of mice were given an adenovirus overexpressing lucif-
erase (Adluc) or IL-4 (AdIL-4) which induces local IL-13 and
increase in AHR in response to methacholine (mean IL-13 con-
centrations in AdIL-4-treated mice was 358 ? 68 pg/ml vs
5.6 ? 2.2 in Adluc-treated mice). Overexpression of IL-4 or
IL-17 in the lung was sufficient to cause significant increases in
airway resistance in response to methacholine challenge (Fig.
5C). AdIL-4 caused a greater shift in the methacholine dose-
response curve with significantly higher airway resistance (Rn)
values in mice administered the mid-range dose of 12.5 mg/ml.
At the 6.25-mg/ml dose and the 25-mg/ml dose, there was no
difference between AdIL-4 and AdIL-17, but both were signif-
icantly higher than Adluc control mice. These data that show
IL-17 overexpression is sufficient to induce AHR to methacho-
line in WT mice.
We next examined the AHR mediated by TH2 and TH17 cells
in the adoptive transfer model of Ag-specific airway inflamma-
tion (Fig. 2A). AHR to methacholine was determined 24 h after
the last airway challenge. Fig. 5D depicts the dose response of
methacholine in control mice, mice that received TH2 cells
treated with vehicle, or mice transferred TH2 cells treated with
DEX. Ag-challenged mice that received TH2 cells and vehicle
treatment showed a significant leftward shift of the methacho-
line dose-response curve compared with Ag- challenged control
mice that did not receive T cells (Fig. 5D). This shift was sig-
nificantly attenuated with DEX treatment (Fig. 5D). Ag-chal-
lenged mice that received TH17 cells and vehicle treatment also
showed a significant leftward shift of the methacholine dose-
response curve compared with Ag-challenged control mice that
did not receive T cells (Fig. 5E). However, in contrast to TH2
cell-transferred mice, this shift was significantly attenuated
with DEX treatment (Fig. 5E).
Mechanism of enhanced TH17 cellular responses to DEX
Glucocorticoids exert their effects through binding the GR, result-
ing in nuclear translocation and transactivation of genes containing
glucocorticoid-response elements (12). To determine whether
TH17 cells showed a defect in GR? binding to DEX resulting in
diminished translocation to the nucleus, GR? localization was vi-
sualized by immunocytochemistry in in vitro-polarized THcell
subsets (Fig. 6A). Fluorescent staining showed that the GR? is
primarily cytoplasmic before treatment with DEX, and DEX treat-
ment resulted in a significant increase in nuclear GR? in both cell
types. This observation was confirmed by Western blot, which
showed a decrease in cytoplasmic GR? content (Fig. 6B). Fluo-
rescent microscopy analysis showed a significant increase in nu-
clear GR? in both TH2 and TH17 cells 30 min after DEX treatment
(Fig. 6C). These results indicate that TH17 cells do express GR?
and are not deficient in their ability to translocate GR? to the
nucleus upon glucocorticoid treatment.
Although the ability of GR? to bind glucocorticoids and trans-
locate to the nucleus is intact, the defect may lie at the level of
DNA binding. Suppression of IL-5 by glucocorticoids involves
repression of GATA-3 signaling mediated by GR? binding to the
IL-5 NFAT/AP-1-response element and subsequent recruitment of
histone deacetylase (22). Studies have shown that IL-17 expression
in mouse and human CD4?T cells is dependent on the NFAT and
MAPK pathways (23, 24). Activated GR? may be unable to re-
press NFAT binding to the IL-17 locus, which would explain the
fact that IL-17 production is not attenuated by DEX. Although
there are several mechanisms by which TH17 cells might prevent
activated GR? from repressing NFAT activity, up-regulation of
NFAT expression in response to DEX is one way by which the cell
could mask the drug’s effects. To test this hypothesis, polarized
immunofluorescent microscopy in DEX-treated (1 ?M) and nontreated TH2 and TH17 cells. B, Cytoplasmic protein fractions of DEX-treated and nontreated
TH2 and TH17 cells were immunoblotted for GR? and ?-actin. Samples were loaded in the following order: TH2_PBS, TH2_DEX, TH17_PBS, and
TH17_DEX. C, Florescent intensity of nuclear GR? staining in TH2 and TH17 cells with and without DEX treatment. Data are graphed as mean ? SEM;
?, p ? 0.05 for DEX compared with no DEX conditions. D and E, TH2 (C) or TH17 (D) cells were transfected with NFAT-luciferase before stimulation
with anti-CD3 and anti-CD28 microbeads (6 h) with or without pretreatment (2 h before beads) with DEX; ?, p ? 0.05 control (CNTRL) vs CD3/CD28;
#, p ? 0.05 CD3/CD28 vs CD3/CD28 ? DEX.
Mechanism of TH17 cell resistance to DEX treatment. TH17 cells are not deficient in their ability to translocate GR?. A, GR staining by
4095The Journal of Immunology
TH2 and TH17 cells were transfected with a NFAT luciferase re-
porter plasmid and were stimulated with anti-CD3 and anti-CD28
microbeads in the presence or absence of DEX (Fig. 6, C and D).
DEX significantly inhibited NFAT luciferase activity in TH17
cells, discounting the concept that NFAT activity is steroid inde-
pendent in TH17 cells.
We have shown that reconstitution of SCID mice with TH2 or
TH17 cells in a model of Ag-induced airway inflammation lead to
differential chemokine profiles and cellular influx to the airways.
Adoptive transfer of TH17 cells resulted in increased levels of
CXC chemokines and G-CSF in the BAL fluid and LH following
Ag provocation. We do not believe this is due to homeostatic pro-
liferation due to the short time frame of the transfer model (25) as
well as similar findings were observed in WT mice (Fig. 4). More-
over, the experiment in WT mice vs IL-17RA KO mice demon-
strated that IL-17RA signaling is required for the induction of KC
and G-CSF, as well as neutrophil recruitment after TH17 T cell
transfer (Fig. 4). This was associated with neutrophil influx to the
airways and is exacerbated by DEX treatment. Animal-transferred
TH2 cells in this model exhibit a typical TH2 phenotype charac-
terized by the influx of lymphocytes and eosinophils to the airways
and are sensitive to DEX treatment. The chemokine and inflam-
matory responses elicited by TH17 cell transfer primarily involves
signaling through the IL-17R. This is consistent with the recent
study by Liang et al. (26) that showed that IL-22, another product
of TH17 cells, played a limited role in neutrophil recruitment in an
adoptive transfer model compared with IL-17A or IL-17A/F het-
erodimer. Despite differential chemokine and cellular responses,
both TH2 and TH17 recipient animals exhibited increased AHR
and mucus secretion. TH17 cells secrete IL-17A and F, IL-6, IL-
22, and TNF-? (5). Transfer of TH17 cells to IL-17R KO mice
showed a substantial decrease in CXC chemokine expression, G-
CSF, IL-6 and lung neutrophilia confirming that the TH17 cells are
migrating to the airways to initiate a response and IL-17R signal-
ing is necessary for the phenotype associated with their transfer.
However, the individual contributions of IL-17A or IL-17F ho-
modimers and IL-17A/F heterodimers in AHR remains to be
It has been suggested that IL-17 modulates allergic airway in-
flammation by dampening Th2 cytokine responses (14, 27). One
study showed that Ab neutralization of IL-17 before OVA chal-
lenge in sensitized mice resulted in decreased neutrophil influx to
the airways but increased airway eosinophilia that those authors
attributed to enhanced serum and BAL fluid IL-5 levels in these
animals (27). We found that the transfer of TH17 cells to WT
BALB/c mice resulted in very low and variable Th2 cytokine re-
sponses and the IL-17R KO mice did not exhibit an exacerbated
Th2 response. One explanation of these divergent findings is that
IL-17 signaling is required for the initiation of Ag-mediated air-
way inflammation but functions to dampen Th2 responses there-
after. This was suggested by studies showing that IL-17R KO mice
exhibited decreased airway eosinophilia and IL-5 in an OVA-in-
duced model of pulmonary inflammation, while treating WT ani-
mals with exogenous IL-17 reduced Th2 cytokine levels in BAL
and LH and eosinophil influx (14). The former IL-17R KO data are
in agreement with what we have found in our model of TH17-
induced airway inflammation. To date, the ability of TH17 cells to
directly regulate Th2 cells has not been shown. However, regula-
tion between Th2 and TH17 may not be as important as the pos-
sibility that these Th cell populations are mediating distinct endo-
phenotypes of asthma. Asthma can be classified as atopic (allergic)
and nonallergic. Patients with nonatopic asthma do not have ele-
vated IgEs, tend to have more airway neutrophilia, and are clini-
cally steroid resistant (12). The data presented in our model system
support a role for TH17 cells in nonatopic disease.
DEX treatment of TH17 cell-reconstituted animals resulted in
increased numbers of neutrophils in the airways following allergen
challenge. The mechanism of increased neutrophil numbers in
DEX-treated animals reconstituted with TH17 cells is not clear.
The expression of IL-17 and CXCL8 is increased in the sputum of
asthmatic patients and positively correlates with each other and
with neutrophil levels in the sputum (28). Our data suggest that
increased levels of neutrophil chemoattractants and G-CSF, which
has been shown to be an important survival factor for neutrophils,
may be a mechanism of enhanced recruitment and survival of neu-
trophils following DEX treatment in TH17-reconstituted animals.
This is fitting with published reports that corticosteroids down-
regulate the CC chemokines CCL2 and CCL11 while exacerbating
the CXCL8 response in the airways of asthmatic patients (29). This
same study found that corticosteroids decreased airway eosino-
philia but increased the number of neutrophils in the airways. Neu-
trophils are relatively steroid resistant compared with T cells and
eosinophils and glucocorticoids enhance survival of neutrophils in
vitro (10, 30). In vitro neutralization of another neutrophil survival
factor GM-CSF did not alter neutrophil survival following glu-
cocorticoid treatment (31). Glucocorticoids exert their effects
through binding the GR, resulting in nuclear translocation and
transactivation of genes containing glucocorticoid-response ele-
ments (32). It has been suggested that human neutrophils express
higher levels of the dominant-negative isoform of the GR, GR?
(19), rendering them nonresponsive to glucocorticoids. However,
murine cells do not express GR? and we observed equivalent nu-
clear translocation of GR to the nucleus of Th2 and TH17 cells and
a similar ability to inhibit NFAT transcriptional activation.
Multiple mechanisms of steroid-resistant asthma have been de-
scribed. One study found that steroid-resistant asthmatics fell into
two categories based on GR-binding and expression patterns; one
group of patients exhibited increased GR number but reduced GR
binding affinity for glucocorticoids, whereas another subset of ste-
roid-resistant patients had a GR-binding affinity similar to that of
steroid-sensitive patients, but reduced GR expression per cell (33).
Future studies will need to examine GR? binding to regions within
the Il17 and Il22 loci.
In contrast to the TH17 transfer model, in the Th2 transfer model
both lymphocyte and eosinophil recruitment to the airways of Th2
recipient animals treated with DEX and AHR was reduced by
DEX treatment. The reduction in lymphocytes may be due to dif-
ferential DEX sensitivity of chemokines necessary for T cell re-
cruitment or proliferation in vivo. We did not observe differences
in T cell apoptosis of Th2 or TH17 cells in vitro. Both cells showed
?85% viability after DEX treatment for 24 h (data not shown).
However, this does not exclude a potential role for differential
proliferation or apoptosis in vivo. AHR was significantly improved
with DEX treatment, but not to the same levels as the effect of
DEX on airway inflammation. AHR is a hallmark feature of
asthma and can generally be separated into two categories, variable
AHR that occurs during an allergen-induced late asthmatic re-
sponse and persistent AHR. Although some studies link airway
inflammation with AHR, it has been suggested that AHR, espe-
cially persistent AHR, can occur in the absence of airway inflam-
mation (34). Tournoy et al. (35) showed AHR occurred indepen-
dent of eosinophil influx to the airways in a model of house dust
mite-mediated airway inflammation. Clinically, administration of a
mAb to IL-5 to asthmatic patients also significantly decreased the
number or eosinophils in the sputum without altering AHR. In our
model system, AHR is mediated by the CD4?cell populations
4096TH17 CELLS AND AIRWAY INFLAMMATION
transferred to the mice in a mast cell/IgE-independent manner.
Mast cells are resident in vascularized tissue and express high
levels of the IgE receptor Fc?RI. IgE binding and Ag cross-linking
activates mast cells to release inflammatory mediators including
histamine, leukotrienes, cytokines. and chemokines, resulting in
bronchoconstriction (37). Mast cells can potentiate Th2-mediated
allergic inflammation through the release of IL-5 that is important
in eosinophil survival and the release of histamine that directs
dendritic cells to secrete IL-4- polarizing naive cells toward a Th2
phenotype (38, 39). Mast cells are sensitive to glucocorticoids;
therefore, it is possible that a mast cell-dependent model system
would show that Th2-induced AHR is more responsive to DEX
We have shown that reconstitution of SCID mice with TH17
cells in the setting of Ag provocation induces CXC chemokine and
G-CSF secretion and neutrophil influx to the airways and is suf-
ficient to induce mucus hyperplasia and AHR. In the setting of
TH17 cell transfer, chemokine secretion, cellular influx to the air-
ways, and AHR were not sensitive to DEX treatment in these
studies. Conversely, in the setting of Th2 cell transfer, cytokine
secretion, eosinophil influx to the airways, and AHR were sensi-
tive to DEX. These data highlight the complex relationships be-
tween airway inflammation and AHR and support the concept that
TH17 cells may be critical mediators of steroid-resistant airways
inflammation and AHR.
The authors have no financial conflict of interest.
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