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*
Dipartimento di Medicina Sperimentale, Università Magna Graecia di Catanzaro, Catanzaro, Italy;
Department of Pediatric Gastroenterology, St. Bartholomew’s and the Royal London School of Medicine and Dentistry, London, United Kingdom;
Dipartimento di Pediatria, Università di Napoli Federico II, Naples, Italy; and
§
Dipartimento di Medicina Interna, Università di Roma tor Vergata, Rome, Italy
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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. Transcripts for
IL-12/p40 were detected in CD, HP-positive, and
Salmonella colitis patients, but not in celiac disease,
indicating that IL-12Rß2 up-regulation occurs only in
IL-12-associated Th1 gastrointestinal diseases. Finally, we showed that
stimulation of lamina propria mononuclear cells with IL-12 enhanced
IL-12Rß2, suggesting that IL-12 regulates IL-12Rß2 expression in
human gastrointestinal mucosa. The data show that the signaling pathway
used by IL-12 to induce Th1 differentiation is increased at the site of
disease in CD, further supporting the view that IL-12/IL-12R signals
contribute to the inflammatory response in this
condition. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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-secreting cells in
this condition (2, 3, 4, 5). Furthermore, studies in murine
models have demonstrated that neutralization of IL-12 leads to rapid
and complete recovery of experimental colitis resembling CD
(6). Signal transduction by IL-12 results in rapid
phosphorylation and activation of STAT molecules (7).
Although IL-12 can activate both STAT3 and STAT4, the effect of IL-12
on Th1 cell differentiation depends specifically on the expression of
STAT4. Indeed, T cells from STAT4-deficient mice manifest impaired
IFN- production in response to IL-12 and are unable to promote
the development of colitis when transferred to immunodeficient mice
(8, 9). In contrast, overexpression of STAT4 in
transgenic mice results in the induction of Th1-mediated colitis
(10). Taken together these observations support the
concept that the IL-12/STAT4 signaling pathway is important in
promoting Th1 cell activation and causing tissue injury in the
intestine (11, 12). The T cell response to IL-12 is dependent on the expression of high affinity IL-12R composed of two subunits, termed IL-12Rß1 and IL-12Rß2 (13). Studies in both humans and experimental models have demonstrated that the responsiveness to IL-12 of Th1 cells and the lack of responsiveness of Th2 cells correlate with the differential expression of the IL-12R chains in these two cell types. Th1 cells express both the IL-12Rß1 and IL-12Rß2 subunits, whereas Th2 cells express only the IL-12Rß1 chain. Although Th1 and Th2 cells can bind IL-12, only Th1 cells are capable of signaling in response to IL-12 (14, 15). These observations indicate that the IL-12Rß2 chain is the signaling component of the IL-12R. This is in agreement with the demonstration that IL-12Rß2, in contrast to IL-12Rß1, contains tyrosine residues in its cytoplasmic domain and directly interacts with STAT4 (13, 16). The level of IL-12Rß2 can therefore be crucial in determining the balance of Th1/Th2 cytokines during the course of an immune response (17). Consistent with this idea, a preferential expression of IL-12Rß2 has been documented in human diseases characterized by a typical Th1-type inflammatory response (18, 19).
In this study we investigated IL-12Rß2 expression in CD
tissue. The hypothesis tested was that increased IL-12Rß2 expression
can contribute to the polarization of the Th1-type cytokine profile in
CD by promoting IL-12 signaling through the STAT4 pathway. We show here
that IL-12Rß2 is enhanced at the site of disease in CD, and that
IL-12Rß2 expression correlates with the activation of STAT4 proteins
and IFN- accumulation. In addition, we provide evidence that
up-regulation of IL-12Rß2 occurs in IL-12-associated Th1
gastrointestinal diseases, suggesting that IL-12 enhances the
expression of its own receptor in human gastrointestinal mucosa. In
aggregate, our data support the concept that IL-12/IL-12R-mediated
signals contribute to the local immune inflammatory response in
CD.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Mucosal samples were taken from freshly obtained intestinal resection specimens of four patients with CD. The primary site of involvement was ileal in one and ileocolonic in three patients. The disease was active in all patients, as defined by a CD activity index >200 (20). At the time of surgery two patients were taking corticosteroids (CS) and two were taking mesalazine plus antibiotics. In all patients indication for surgery was a chronic active course poorly responsive to medical treatment. From patients with ileocolonic involvement, mucosal samples were taken from involved (gross lesions) and spared, ileal and colonic areas.
Additional mucosal samples were taken during endoscopy from 13 CD patients. In these patients the primary site of involvement was ileal in five, ileocolonic in three, and colonic in five. At the time of endoscopy, 11 patients had active disease. Five patients were taking CS, five were taking mesalazine, one was taking mesalazine plus antibiotics, and the remaining two were not receiving treatment.
Controls included colonic mucosal samples taken from involved areas of nine ulcerative colitis (UC) patients undergoing endoscopy, 13 patients with irritable bowel syndrome (IBS) undergoing endoscopy for recurrent abdominal pain, and one patient with diverticular disease. Both IBS and diverticular disease patients were categorized as the non-IBD control group. In addition, biopsy specimens were taken from three patients with infectious (salmonella) colitis. All UC patients had active disease at the time of the study, as defined by clinical criteria (21) supplemented by endoscopic and histopathologic data (22, 23). Disease activity was moderate in two and mild in seven patients. Disease extent was substantial in four and distal in five patients. Two patients were taking CS, five were taking mesalazine, and the remaining two were not receiving treatment.
Autologous PBMC were obtained from three CD and three UC patients, and three non-IBD controls. Biopsy specimens from the distal duodenum of four patients with untreated celiac disease and four normal controls were obtained during upper gastrointestinal endoscopy. Diagnosis of celiac disease was made according to the original or revised European Society for Pediatric Gastroenterology and Nutrition criteria for celiac disease (24, 25). The histopathologic diagnosis was based on typical mucosal lesions with crypt cell hyperplasia, villous atrophy, and increased number of intraepithelial lymphocytes. All celiac disease patients were positive for anti-endomysial and anti-gliadin Abs. Control patients were under investigation for gastrointestinal symptoms, but had normal histology and were anti-endomysial and anti-gliadin Ab negative. Additional samples were taken from the gastric antrum of three patients with documented diagnosis of Helicobacter pylori (HP)-associated gastritis and three normal controls (HP-negative subjects). Biopsy specimens were snap-frozen in liquid nitrogen and stored at -80°C until used.
The study was approved by the department ethical committee.
Lamina propria mononuclear cell (LPMC) isolation and culture
LPMC were isolated by the DTT-EDTA-collagenase sequence as previously described (2, 5, 23). The isolated cells were counted and checked for viability using 0.1% trypan blue (viability ranged from 90–94%). PBMC were isolated by density gradient centrifugation (Lymphoprep, Nycomed Pharma, Oslo, Norway) from 10-ml heparinized blood samples.
To analyze which cells express IL-12Rß2, CD3+ lamina propria lymphocytes (LPL) were isolated from biopsy specimens of three patients with CD and three normal controls. CD3+ LPL were purified incubating LPMC with immunomagnetic beads armed with mAb for CD3 according to the instructions of the manufacturer (Dynal, Oslo, Norway). Purified cells were >93% as determined by FACS analysis.
To investigate whether IL-12 enhances IL-12Rß2 expression, normal
LPMC were resuspended in complete medium (RPMI 1640 supplemented with
10% FCS, 1% L-glutamine, 100 U/ml penicillin, and 100
µg/ml streptomycin; all from Sigma, St. Louis, MO) at a concentration
of 2 x 106 cells/ml and cultured in 24-well
plates in the presence of PHA (1 µg/ml; Sigma) for 12 h. After
that, nonadherent LPMC were collected, washed twice with 1x PBS, and
cultured in the absence or the presence of graded doses of recombinant
human IL-12 (Sigma; final concentration ranging from 0.1–10 ng/ml) for
6 h. To parallel LPMC cultures were added 10 ng/ml IL-12 and
either a neutralizing IL-12 or IFN- Ab (both used at a final
concentration of 1 µg/ml; both purchased from Sigma). To verify the
efficiency of the anti-IFN- Ab, nonadherent LPMC cultures were
also stimulated with 10 ng/ml IFN- in the presence or the absence of
anti-IFN- (1 µg/ml). In additional experiments LPMC were
isolated from the inflamed colon of four patients with CD and cultured
(2 x 106 cells/ml) in the presence of a
neutralizing IL-12 Ab or a nonrelevant control Ab (rabbit IgG; 1
µg/ml; both purchased from Sigma) for 24 h. At the end of the
culture, LPMC were collected and used for RNA extraction.
Tissue homogenate preparation
Biopsy or surgical mucosal samples taken from all patients enrolled in this study were used for both RNA and protein analysis on freshly obtained whole tissue. Mucosal samples were separately placed in sterile tubes containing 1–2 ml of cold guanidine thiocyanate buffer (for RNA extraction) or 0.5 ml of lysis buffer (for protein extraction). The latter contained 0.0625 mol/L Tris (pH 6.8), 2% SDS, 3% 2-ME, 10% glycerol, 100 mmol/L sodium fluoride, 10 µg/ml aprotinin, 10 µg/ml leupeptin, and 1 mmol/L PMSF (all from Sigma). Tissue samples were homogenized using a tissue homogenizer (Ystral, Dottingen, Germany).
RNA and cDNA preparation and semiquantitative RT-PCR
Total RNA extracted from freshly obtained mucosal samples and
(both unstimulated and stimulated) LPMC, CD3+
LPL, and CD3+-depleted LPMC were used to prepare
cDNA as previously described (2, 5). In preliminary
experiments we established the optimal number of cycles for obtaining a
PCR product within the linear portion of the curve. For this purpose an
equivalent amount of cDNA per sample (2 µl/reaction) was amplified
using specific primers for ß-actin (for 16, 18, 22, 24, and 26
cycles) or for each IL-12R subunit, IFN-, IL-4, or IL-5 (for 18, 20,
23, 26, and 28 cycles). PCR were performed in a total volume of 50 µl
as previously described (2, 26). For Southern blotting
experiments cDNA samples were incubated for 18 cycles with ß-actin
primers or for 23 cycles with primers for each IL-12R subunit,
IL-12/p40, IFN-, IL-4, and IL-5 and were detected using specific
cDNA probes (26). The cDNA probes were DNA fragments
encoding the full-length PCR product. RT-PCR products were used as
probes only after each product was cloned and its sequence verified.
PCR primers (Genosys, Cambridge, U.K.) were as follows: IL-12Rß1,
5'-CTTCCAGAAGGCTGTCAAG-3' and 3'-CTGTGATTCAATGCAATACG-5'; IL-12Rß2,
5'-GGATGCTCATTGGCATTTAT-3' and 3'-CAGGCCAGTTTGCAGACAA-5'; IL-12/p40,
5'-CATTCGCTCCTGCTGCTTCAC-3' and 3'-TACTCCTTGTTGTCCCCTCTG-5';
IFN-, 5'-AATGCAGGTCATTCAGATG-3' and 3'-TTGGACATTCAAGTCAGTT-5';
IL-4, 5'-GCTAGCATGTGCCGGCAACTT-3' and 3'-CAACGTACTCTGGTTGGCTTC-5';
IL-5, 5'-GAGGATTCCTGTTCCTGT-3' and 3'-GCGCAACAAACCAGTTTAG-5'; and
ß-actin, 5'-CGAGGCCCAGAGCAAGAGA-3' and
3'-CGTGACATTAAGGAGAAGCTGTG-5'. The level of RNA transcripts was
measured by laser densitometry and expressed as arbitrary units.
Determination of phosphorylated STAT4 level
Total proteins were extracted from freshly obtained mucosal samples by using the above-mentioned lysis buffer. After cell lysis the supernatant was collected, run at 4000 x g for 40 min (4°C), and stored at -80°C until assay. Total proteins (500 µg/sample) were incubated with anti-STAT4 (C-20; Santa Cruz Biotechnology, Santa Cruz, CA) at 4°C for 2 h. Immune complexes were collected by incubation with protein A/G agarose (Santa Cruz Biotechnology), washed three times with lysis buffer, and heated for 5 min in a boiling water bath in sample buffer for SDS-PAGE. Immunoprecipitates from extracts containing the same amount of protein were analyzed by Western blotting with Ab against phosphotyrosine (p-Tyr; Santa Cruz Biotechnology) and subsequent incubation with HRP-conjugated goat anti-mouse IgG mAb (Santa Cruz Biotechnology). The Ab reaction was detected with a chemiluminescence detection kit (Amersham International, Arlington Heights, IL). After p-Tyr analysis, blots were stripped by incubation for 30 min at 50°C in stripping medium (2% SDS, 0.05 M Tris, and 0.1 M 2-ME) and then incubated with Ab against STAT4 (H-119; Santa Cruz Biotechnology).
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Transcripts for IL-12Rß2 were detected in tissue homogenates
from both affected and unaffected intestinal mucosal areas of CD
patients. Similarly, transcripts for IL-12Rß2 were found in mucosal
samples taken from patients with UC and non-IBD controls. In addition,
IL-12Rß2 was expressed in freshly isolated LPMC from CD and UC
patients as well as in those from non-IBD controls. When the IL-12Rß2
content was examined by a semiquantitative RT-PCR, an increased
accumulation was seen in whole mucosal samples from CD compared with UC
and non-IBD controls (Fig. 1
). In CD,
IL-12Rß2 expression was more abundant in mucosal samples taken from
affected areas compared with that in spared mucosa (Fig. 1). No
difference in terms of IL-12Rß2 RNA transcripts was observed between
spared mucosa of CD patients and UC or normal controls. IL-12Rß2 RNA
level in active UC did not differ from that in non-IBD controls (Fig. 1). To establish which cells express IL-12Rß2, total RNA was
extracted from both CD3+ LPL and
CD3+-depleted LPMC and analyzed by Southern
blotting after PCR amplification. As shown in Fig. 2, both CD3+ LPL
and CD3+-depleted LPMC contained transcripts for
IL-12Rß2. However, an enhanced accumulation of IL-12Rß2 RNA
transcripts was observed only in CD3+ LPL from CD
compared with controls (Fig. 2).
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).
Both IL-12Rß1 and IL-12Rß2 were barely detectable in PBMC (data not
shown).
In CD, IL-12Rß2 expression strictly correlates with tyrosine
phosphorylation of STAT4 and IFN- expression
STAT4 is an essential component of the IL-12-dependent pathway for
IFN- production (7, 8). There is good evidence that the
phosphorylation and activation of STAT4 in response to IL-12 are
dependent on the presence of IL-12Rß2 (14, 16, 27, 28).
To examine whether up-regulation of IL-12Rß2 was associated with a
pronounced expression of active STAT4, protein extracts from whole
mucosal samples were immunoprecipitated with anti-STAT4 Ab and
immunoblotted with anti-phosphotyrosine Ab. The level of STAT4
phosphorylation in affected mucosal areas of CD was greater than that
in UC and non-IBD controls, although all these groups expressed
comparable amounts of the STAT4 proteins (Fig. 3). In paired mucosal biopsy specimens
available from three CD patients, three UC patients, and three non-IBD
controls, the profile of regulatory cytokines was analyzed by Southern
blotting. As shown in Fig. 4, a strong
accumulation of transcripts for IFN- was detected in CD mucosal
samples. Transcripts for IL-4 were expressed at very low levels in both
CD and UC as well as non-IBD control mucosa (Fig. 4). IL-5 RNA
transcripts were detected only in UC (Fig. 4).
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To investigate whether up-regulation of IL-12Rß2 is a feature of
Crohn’s disease or occurs in other Th1-mediated gastrointestinal
diseases, the content of IL-12Rß2 RNA was measured in mucosal samples
taken from the distal duodenum of patients with celiac disease and the
gastric antrum of patients with HP-associated gastritis. In addition,
IL-12Rß2 RNA transcripts were analyzed in mucosal samples of patients
with infectious colitis. For all these groups of patients appropriate
controls were included. As shown in Fig. 5, the amount of transcripts for
IL-12Rß2 in the gastric mucosa of HP-infected patients was greater
than that detected in the mucosa of HP-negative subjects. Similarly,
the level of IL-12Rß2 RNA was greater in patients with infectious
colitis than in normal controls (Fig. 5). In contrast, the IL-12Rß2
RNA level in celiac disease duodenum did not differ from that in normal
duodenal mucosa (Fig. 5).
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). In addition,
transcripts for IL-12/p40 were barely detectable in patients with UC
(Fig. 6) and non-IBD controls, confirming previous observations
(2, 3, 4). Together, these data indicate that up-regulation
of the IL-12Rß2 chain occurs only in IL-12-associated Th1
gastrointestinal diseases.
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Recent reports have demonstrated that IL-12 can regulate the
expression of IL-12Rß2 on T cells (15, 29). These data
together with the documented observation that IL-12Rß2 is enhanced in
IL-12-associated Th1 gastrointestinal diseases prompted us to
investigate whether IL-12 can enhance IL-12Rß2 expression in human
gastrointestinal mucosa. To address this issue, nonadherent LPMC
isolated from normal controls were cultured with exogenous IL-12, and
the amount of IL-12Rß2 RNA transcripts was examined by Southern
blotting after PCR amplification. As shown in Fig. 7 (upper panel), IL-12
enhanced LPMC IL-12Rß2, and this effect was inhibited by the addition
of a neutralizing anti-IL-12 Ab. As IL-12 is a potent inducer of
IFN-, and IFN- has the ability to enhance IL-12Rß2, we next
examined whether the effect of IL-12 on IL-12Rß2 was dependent by the
induction of IFN-. For this purpose, in parallel experiments
nonadherent LPMC were cultured with exogenous IL-12 in the presence of
a neutralizing anti-IFN- Ab, and the amount of IL-12Rß2 RNA
transcripts was examined by Southern blotting after PCR amplification.
Interestingly, the anti-IFN- reduced, but did not completely
abrogate, the induction of IL-12Rß2 RNA by IL-12 (Fig. 7, upper
panel). Finally, we showed that addition of anti-IL-12 Ab to
the CD LPMC cultures resulted in a marked inhibition of IL-12Rß2
(Fig. 7, lower panel).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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One important finding of the present study is that CD LPMC, but not
autologous PBMC, express high levels of IL-12Rß2. CD is a chronic
inflammatory disorder of the gastrointestinal tract characterized by an
infiltration of the inflamed regions with CD4+ T
cells and macrophages (1). These cells are functionally
activated and produce high levels of IFN- and TNF-
, indicative of
a Th1 cytokine profile (30, 31, 32, 33). Consistently, we and
others have recently found elevated levels of IL-12, the major Th1
inducing factor, in CD mucosa and have shown that boosting lamina
propria Th1 cell responses with IL-12 produces severe mucosal
degradation (2, 3, 4, 12). These observations together with
the demonstration that activation of the IL-12/STAT4 pathway in murine
models results in CD-like colitis support the pathogenic role of IL-12
in CD (6, 9, 10, 11). Data from the present study confirm and
expand these observations showing that in CD mucosa, up-regulation of
the IL-12Rß2 chain is tightly correlated with the accumulation of
both active STAT4 and IFN-. Because IL-12Rß2 directly interacts
with STAT4, it is conceivable that the increased expression of
IL-12Rß2 contributes to stabilize the polarized Th1 phenotype in CD
by maintaining mucosal T cells in a state of functional responsiveness
to IL-12 and thereby promoting IL-12 signaling through the STAT4
pathway (13, 14, 15, 16, 17).
In this study the expression of IL-12Rß2 was analyzed at the mRNA level only, because no commercially Ab capable of specifically and selectively recognizing the distinct subunit of IL-12R is as yet available. The possibility that the content of transcripts for IL-12Rß2 is not associated with a pronounced induction of the IL-12Rß2 protein should therefore be considered. However, it is worth noting that in other systems IL-12-dependent signaling correlates with the selective expression of the transcripts encoding the IL-12Rß2 chain (14, 15).
Although the mechanism by which IL-12Rß2 expression is regulated in the human gastrointestinal mucosa remains to be clarified, some observations made in the present study suggest that bacteria and bacterial products/components may contribute to modulate IL-12Rß2. Indeed, IL-12Rß2 was increased in HP-associated gastritis and Salmonella colitis, two infectious entities, and in CD, a disease characterized by an abnormal mucosal immune response to microbial agents derived from the intestinal luminal flora (34). In contrast, no increase in IL-12Rß2 was seen in UC. These data fit into the concept that the immune response in CD differs from that in UC (1) and suggest that UC may be the atypical response to infectious etiologies, whereas the response in CD is the same as that in infections.
Studies in several experimental models of bacterial infections and in
human diseases support the role of the IL-12/IL-12R pathway in the
anti-microbial immune defense (35). Evidence indicates
that IL-12 is required both for early control of infection, through the
stimulation of NK cell IFN- production, and for generation and
perhaps maintenance of acquired memory response, directed by Th1 cells
(35, 36, 37). Importantly, in diseases due to intracellular
pathogens, such as Mycobaterium tuberculosis and
Salmonella, reduced expression of IL-12R has been associated
with severe manifestations of the diseases due to an impaired ability
to mount a protective IL-12-dependent Th1 response (36).
It can thus be assumed that during Salmonella colitis,
up-regulation of IL-12Rß2 is an essential requirement to maintain
cell responsiveness to IL-12 and to establish a protective immunity
against the pathogen (38).
The fact that IL-12Rß2 is increased in CD, HP-associated gastritis,
and Salmonella colitis is consistent with previous studies
showing that IL-12Rß2 is highly expressed in Th1 cell lines and
established Th1-mediated diseases (14, 15, 18, 19).
However, we were able to detect no increase in IL-12Rß2 in duodenal
samples from patients with celiac disease, a gluten-sensitive
Th1-mediated enteropathy (39, 40). Our data also indicate
that in the gastrointestinal mucosa up-regulation of IL-12Rß2 occurs
only in IL-12-associated diseases and suggest that IL-12 may directly
influence the level of IL-12Rß2 on T cells. First, we detected
transcripts for IL-12 in CD, HP-associated gastritis, and
Salmonella colitis, but not in celiac disease, confirming
the recent observation that IL-12 is undetectable in celiac disease
mucosa (39). Second, we showed that a neutralizing IL-12
Ab dramatically down-regulated IL-12Rß2 expression in CD LPMC.
Finally, we demonstrated that the addition of IL-12 to normal LPMC
cultures resulted in an increase in IL-12Rß2. The effect of IL-12 on
LPMC IL-12Rß2 expression was reduced, but was not completely
abrogated, by a neutralizing IFN- Ab. This supports results from
studies of other systems showing that IL-12 can enhance IL-12Rß2
through a mechanism that is only in part dependent on IFN-
(14, 15, 17, 29).
Transcripts for IL-12Rß1 were detected in all intestinal mucosal samples analyzed. This result apparently contrasts with our previous negative finding of IL-12Rß1 RNA in purified normal lamina propria T lymphocytes (5). Differences in the samples and the amount of RNA analyzed as well as in the methods used might well account for such discrepancy. In contrast to IL-12Rß2, the content of IL-12Rß1 in CD mucosa did not differ from that in UC or non-IBD controls, clearly indicating that the expression of the IL-12R subunit is differently regulated in the human intestine during chronic inflammation.
In conclusion, our data show that the signal pathway used by IL-12 to promote Th1 cell development is enhanced at the mucosal level in CD, further supporting the idea that IL-12/IL-12R signals contribute to the local inflammatory response in CD. Studies are now in progress to explore whether molecules inhibiting the binding of IL-12Rß2 with STAT4 can dampen IL-12-driven Th1 responses in the intestinal mucosal microenvironment.
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Francesco Pallone, Cattedra di Gastroenterologia, Dipartimento di Medicina Sperimentale Policlinico Universitario, Via T. Campanella, 88100 Catanzaro, Italy.
3 Abbreviations used in this paper: CD, Crohn’s disease; CS, corticosteroids; LPMC, lamina propria mononuclear cells; LPL, lamina propria lymphocytes; UC, ulcerative colitis; IBD, inflammatory bowel diseases; HP, Helicobacter pylori.
Received for publication February 7, 2000. Accepted for publication September 6, 2000.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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-producing CD4+ T cells that respond to bacterial antigens. J. Immunol. 162:1884. secretion and not restricted to T and NK cells. J. Immunol. 163:5257. by intestinal lamina propria lymphocytes in Crohn’s disease: kinetics of in vitro response to interferon inducers. Gut 32:403., whereas ulcerative colitis LP cells manifest increased secretion of IL-5. J. Immunol. 157:1261.[Abstract]
secreting T cells in normal and diseased human intestinal mucosa. Immunology 78:127.[Medline]
in patients with celiac disease. Gastroenterology 115:551.[Medline]
producing cells in the lamina propria in coeliac disease. Digest. Dis. Sci. 39:2243.
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I Monteleone, P Vavassori, L Biancone, G Monteleone, and F Pallone Immunoregulation in the gut: success and failures in human disease Gut, May 1, 2002; 50(90003): iii60 - 64. [Abstract] [Full Text] [PDF]
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R. Rad, M. Gerhard, R. Lang, M. Schoniger, T. Rosch, W. Schepp, I. Becker, H. Wagner, and C. Prinz The Helicobacter pylori Blood Group Antigen-Binding Adhesin Facilitates Bacterial Colonization and Augments a Nonspecific Immune Response J. Immunol., March 15, 2002; 168(6): 3033 - 3041. [Abstract] [Full Text] [PDF]
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J Bauditz, S Wedel, and H Lochs Thalidomide reduces tumour necrosis factor {alpha} and interleukin 12 production in patients with chronic active Crohn's disease Gut, February 1, 2002; 50(2): 196 - 200. [Abstract] [Full Text] [PDF]
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 N. S. Goncalves, M. Ghaem-Maghami, G. Monteleone, G. Frankel, G. Dougan, D. J. M. Lewis, C. P. Simmons, and T. T. MacDonald Critical Role for Tumor Necrosis Factor Alpha in Controlling the Number of Lumenal Pathogenic Bacteria and Immunopathology in Infectious Colitis Infect. Immun., November 1, 2001; 69(11): 6651 - 6659. [Abstract] [Full Text] [PDF]
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