CpG methylation of the IFNG gene as a mechanism to induce immunosuppression [correction of immunosupression] in tumor-infiltrating lymphocytes

The execution of appropriate gene expression patterns during immune responses is of eminent importance where CpG methylation has emerged as an essential mechanism for gene silencing. We have charted the methylation status of regulatory elements in the human IFNG gene encoding the signature cytokine of the Th1 response. Surprisingly, human naive CD4(+) T lymphocytes displayed hypermethylation at the IFNG promoter region, which is in sharp contrast to the completely demethylated status of this region in mice. Th1 differentiation induced demethylation of the IFNG promoter and the upstream conserved nucleotide sequence 1 enhancer region, whereas Th2-differentiated lymphocytes remained hypermethylated. Furthermore, CD19(+) B lymphocytes displayed hypomethylation at the IFNG promoter region with a similar pattern to Th1 effector cells. When investigating the methylation status among tumor-infiltrating CD4(+) T lymphocytes from patients with colon cancer, we found that tumor-infiltrating lymphocytes cells are inappropriately hypermethylated, and thus not confined to the Th1 lineage. In contrast, CD4(+) T cells from the tumor draining lymph node were significantly more demethylated than tumor-infiltrating lymphocytes. We conclude that there are obvious interspecies differences in the methylation status of the IFNG gene in naive CD4(+) T lymphocytes, where Th1 commitment in human lymphocytes involves demethylation before IFNG expression. Finally, investigations of tumor-infiltrating lymphocytes and CD4(+) cells from tumor draining lymph node demonstrate methylation of regulatory regions within key effector genes as an epigenetic mechanism of tumor-induced immunosuppression.

Different regulation of eosinophil activity in Crohn's disease compared with ulcerative colitis

The aim of this investigation was to study the involvement of eosinophil and neutrophil granulocytes in different stages of Crohn's disease (CD) and ulcerative colitis (UC). Biopsy samples were taken from the right flexure of the colon and from the rectum in patients with active (n=12) and inactive colonic CD (n=7), patients with active (n=33) and inactive UC (n=24), and from control subjects (n=11). Cell suspensions from biopsies and blood were analyzed by flow cytometry with regards to activation markers and viability. Immunohistochemistry was used to evaluate cell number and degranulation. Blood eosinophils were cultured with Th1 and Th2 cytokines, and the expression of activity markers was assessed by flow cytometry. Eosinophil number, viability, and activity were increased during active CD and UC compared with controls. The activity, assessed as CD44 expression, tended to diminish during inactive CD but was increased further in quiescent UC. Neutrophil number and activity were increased only during inflammation in both diseases. Culture of blood eosinophils with IL-5 and IL-13 caused increased CD44 expression, whereas IL-5 and IFN-gamma induced elevated CD69 expression. We observed different patterns of eosinophil activation in CD and UC, with the highest CD44 expression during quiescent UC. Our in vitro experiments with recombinant cytokines suggest that the diverse mechanisms of eosinophil activation in CD and UC are a result of different cytokine milieus (Th1 vs. Th2). In contrast, neutrophil activation reflects the disease activity in CD and UC, irrespective of Th cell skewing.

Decreased numbers of FoxP3-positive and TLR-2-positive cells in intestinal mucosa are associated with improvement in patients with active inflammatory bowel disease following selective leukocyte apheresis

BACKGROUND

Impaired immunological tolerance to commensal enteric flora is considered one possible pathogenic mechanism of inflammatory bowel disease (IBD). Given that regulatory T cells and Toll-like receptor (TLR)-positive cells are key actors in mucosal immune regulation, we aimed to identify the dynamics of these actors in the intestinal mucosa in relation to clinical improvement following selective leukapheresis treatment.

METHODS

Ten patients with active IBD despite treatment with corticosteroids, immunomodulators, or anti-tumor necrosis factor therapy were assessed by immunohistochemical staining of colorectal mucosal biopsies obtained before and after five sessions (week 7) of granulocyte and monocyte adsorption apheresis (GCAP). The presence of FoxP3-positive regulatory T cells, macrophages, dendritic cells, and TLR-2 and-4 positive cells was determined in relation to short-(week 7) and long-term (week 52) clinical outcome data.

RESULTS

Following GCAP, the number of FoxP3-(P = 0.012) and TLR-2 (P = 0.008)-positive cells significantly decreased in biopsies after 7 weeks, in parallel with both clinical improvement at week 7 and a longstanding response after 12 months.

CONCLUSIONS

Downregulation of FoxP3 and TLR-2 cells in the colorectal mucosa mirrors both short-and long-term improvement in patients with active IBD responding to GCAP. This observation suggests a potential role of these cells in the pathogenesis of IBD and the induction of immunological tolerance in the mucosa.

Antibodies to amino acid 200-239 (p200) of Ro52 as serological markers for the risk of developing congenital heart block

Maternal autoantibodies to the p200-epitope of Ro52 have been suggested to correlate with development of congenital heart block. The aim of the present study was to evaluate the clinical relevance and predictive value of p200-antibodies in high-risk pregnancies. Sera from 515 Finnish, Swedish and American women were included in the study. Sera originated from 202 mothers with an infant affected by second- or third-degree atrioventricular block (AVB), 177 mothers with rheumatic disease having infants with normal heart rate and female blood donors (n = 136). A novel serological assay for Ro52 p200-antibodies with intra- and inter-assay variability of 3% and 3.8% respectively was developed. Mothers of children affected by AVB II-III had significantly higher p200-antibody levels than mothers with rheumatic disease having children with normal heart rate (P < 0.001). In the Swedish cohort, a distinction between foetuses with normal conduction, AVB I, AVB II and III was possible. A significant difference in anti-p200 levels between AVB I and AVB II-III groups compared with foetuses with normal conduction (P < 0.05 and P < 0.01) was observed. Using p200-antibodies as a second step analysis in Ro52-positive pregnancies increased the positive predictive value for foetal cardiac involvement (AVB I, II or III) from 0.39 (0.27-0.51) to 0.53 (0.37-0.68). In conclusion, Ro52 p200-antibodies may occur in women with unaffected children, but levels are significantly higher in mothers of children with congenital heart block and are suggested as a relevant marker in evaluating the risk for foetal AV block.

Detection of Immune Responses in Sentinel Nodes Draining Human Urinary Bladder Cancer

Being the first lymph node to receive drainage from the tumour area, the sentinel node offers a unique possibility to obtain tumour‐reactive lymphocytes. We investigated antitumour immune responses in sentinel nodes from patients with bladder cancer, by assaying tumour‐specific proliferation and TCR Vβ repertoires. During tumour surgery, sentinel lymph nodes were identified by peri‐tumoural injection of blue dye. Fresh specimens of tumour, sentinel and nonsentinel lymph nodes were obtained, and single‐cell suspensions were prepared. Cells were assayed for reactivity against autologous tumour extract in [³H]‐thymidine incorporation assays and characterized by flow cytometry. Parallel analyses of the expression of Vβ gene families were performed with padlock probes, linear oligonucleotides which upon target recognition can be converted to circular molecules by a ligase. Probes were reacted with cDNA prepared from magnetically separated CD4⁺ cells, and the TCR repertoire was determined by hybridizing the products to oligonucleotide microarrays. Dose‐dependent proliferation in response to tumour extract could be detected in sentinel lymph nodes. Common clonal expansions were detected among tumour‐infiltrating lymphocytes and in sentinel lymph nodes. Nonsentinel lymph nodes displayed a divergent TCR Vβ repertoire. These results indicate an ongoing immune response against tumour antigens in sentinel nodes, draining urinary bladder cancer. Identification of sentinel lymph nodes makes it possible to obtain tumour‐reactive lymphocytes for use in adoptive immunotherapy.

Aire deficiency causes increased susceptibility to streptozotocin-induced murine type 1 diabetes

Aire-deficient mice are a model of the human monogenic disorder autoimmune polyendocrine syndrome type I (APS I) characterized by a progressive autoimmune destruction of multiple endocrine glands such as the adrenal cortex, the parathyroids and the beta-cells of the pancreas. The disease is caused by mutations in the autoimmune regulator (AIRE) gene, a putative transcription factor expressed in thymic medullary epithelial cells and in antigen-presenting cells of the myeloid lineage in peripheral lymphoid organs. As Aire(-/-) mice do not spontaneously develop endocrinopathies, we wanted to evaluate the autoimmune multiple low-dose streptozotocin (MLDSTZ) diabetes model in Aire(-/-) mice. Surprisingly, Aire heterozygote mice were most susceptible to MLDSTZ-induced diabetes, whereas Aire(-/-) mice displayed an intermediate sensitivity to diabetes. Furthermore, Aire(-/-) macrophages produced higher levels of TNF-alpha and lower levels of IL-10 following streptozotocin stimulation, and Aire(-/-) mice developed a higher frequency of islet cells autoantibodies as a sign of increased activation. However, the number of islet infiltrating F4/80(+) Aire(-/-) macrophages was significantly decreased which was attributed to an increased susceptibility to streptozotocin cytotoxicity of Aire(-/-) macrophages. In conclusion, Aire(-/-) macrophages display an increased activation after STZ stimuli, but suffer from increased susceptibility to STZ cytotoxicity. These results support an important function of Aire in the control of peripheral tolerance through myeloid antigen-presenting cells.

Metinel node--the first lymph node draining a metastasis--contains tumor-reactive lymphocytes

Background

We previously identified tumor-reactive lymphocytes in the first lymph nodes that drain the primary tumor. In this study, we performed lymphatic mapping to investigate the possibility of finding the first lymph nodes that drain metastases, and of learning whether these lymph nodes contained tumor-reactive lymphocytes suitable for adoptive immunotherapy.

Methods

Nineteen patients were studied. The primary tumor site was colorectal cancer in seven patients, malignant melanoma in four, ovarian cancer and breast cancer in two, and one each with pancreatic cancer, cholangiocarcinoma, leiomyosarcoma, and squamous cellular cancer of the tongue. By injection of Patent blue dye or radioactive tracers around the metastases, we identified draining lymph nodes from liver metastases (n = 9), intra-abdominal local recurrences (n = 3), and regional lymph node metastases (n = 7). In six patients, a preoperative lymphoscintigraphy was performed.

Results

We located the first draining lymph node or nodes from metastases or local recurrences; we named them “metinel nodes.” Lymphocytes from the metinel nodes proliferated, showed clonal expansion, and produced interferon gamma (via in vitro expansions on stimulation with tumor homogenate) and interleukins, all of which demonstrate the characteristics of tumor-reactive lymphocytes. Eight of the nineteen patients received immunotherapy on the basis of tumor-reactive T cells derived from the metinel nodes.

Conclusions

We demonstrate that it is possible to locate the first lymph nodes draining subcutaneous, lymphatic, and visceral metastases, the so-called metinel nodes. Metinel node–derived lymphocytes may be used to treat disseminated solid cancer, and clinical trials should evaluate the effect of such treatment.

FOXP3 promoter demethylation reveals the committed Treg population in humans

BACKGROUND

Naturally occurring thymus derived regulatory T cells (Tregs) are central in the maintenance of self-tolerance. The transcription factor FOXP3 is crucial for the suppressive activity of Tregs and is considered the most specific marker for this population. However, human non regulatory T cells upregulate FOXP3 transiently upon activation which calls for other means to identify the Treg population. Since epigenetic mechanisms are involved in the establishment of stable gene expression patterns during cell differentiation, we hypothesized that the methylation profile of the FOXP3 promoter would allow the distinction of truly committed Tregs.

METHODOLOGY/PRINCIPAL FINDINGS

Human CD4(+)CD25(hi) Tregs displayed a demethylated FOXP3 promoter (1.4%+/-0.95% SEM methylated) in contrast to CD4(+)CD25(lo) T cells which were partially methylated (27.9%+/-7.1%). Furthermore, stimulated CD4(+)CD25(lo) T cells transiently expressed FOXP3 but remained partially methylated, suggesting promoter methylation as a mechanism for regulation of stable FOXP3 expression and Treg commitment. In addition, transient FOXP3 expressing cells exhibited suppressive abilities that correlate to the methylation status of the FOXP3 promoter. As an alternative to bisulphite sequencing, we present a restriction enzyme based screening method for the identification of committed Tregs and apply this method to evaluate the effect of various culturing conditions. We show that a partial demethylation occurs in long-term cultures after activation, whereas the addition of TGF-beta and/or IL-10 does not induce any additional change in methylation level.

CONCLUSIONS/SIGNIFICANCE

The unique FOXP3 promoter methylation profile in Tregs suggests that a demethylated pattern is a prerequisite for stable FOXP3 expression and suppressive phenotype. Presently, FOXP3 is used to identify Tregs in several human diseases and there are future implications for adoptive Treg transfer in immunotherapy. In these settings there is a need to distinguish true Tregs from transiently FOXP3(+) activated T cells. The screening method we present allows this distinction and enables the identification of cells suitable for in vitro expansions and clinical use.

Class A scavenger receptors regulate tolerance against apoptotic cells, and autoantibodies against these receptors are predictive of systemic lupus

Apoptotic cells are considered to be a major source for autoantigens in autoimmune diseases such as systemic lupus erythematosus (SLE). In agreement with this, defective clearance of apoptotic cells has been shown to increase disease susceptibility. Still, little is known about how apoptotic cell-derived self-antigens activate autoreactive B cells and where this takes place. In this study, we find that apoptotic cells are taken up by specific scavenger receptors expressed on macrophages in the splenic marginal zone and that mice deficient in these receptors have a lower threshold for autoantibody responses. Furthermore, antibodies against scavenger receptors are found before the onset of clinical symptoms in SLE-prone mice, and they are also found in diagnosed SLE patients. Our findings describe a novel mechanism where autoantibodies toward scavenger receptors can alter the response to apoptotic cells, affect tolerance, and thus promote disease progression. Because the autoantibodies can be detected before onset of disease in mice, they could have predictive value as early indicators of SLE.

Defect internalization and tyrosine kinase activation in Aire deficient antigen presenting cells exposed to Candida albicans antigens

Patients with Autoimmune polyendocrine syndrome type I (APS I) present with multiple endocrine failures due to organ-specific autoimmune disease, thought to be T-cell-mediated. Paradoxically, APS I patients suffer from chronic mucocutaneous candidiasis. The mutated gene has been identified as the Autoimmune regulator (AIRE). Aire is expressed in medullary epithelial cells of the thymus and in antigen presenting cells in the periphery. T cells from Aire deficient mice and men displayed an enhanced proliferative response against Candida antigen in vitro, suggesting that Aire deficient T cells are competent in recognizing Candida albicans. In contrast, monocytes from APS I patients displayed a decreased and delayed internalization of zymosan. Furthermore, Candida antigen activated monocytes from APS I patients show decreased and altered phoshotyrosine kinase activation. In conclusion, Aire deficient APCs have a defect receptor mediated internalization of Candida which affects kinase activation, likely altering the innate Candida immune response.

Aire-deficient mice develop hematopoetic irregularities and marginal zone B-cell lymphoma

Autoimmune polyendocrine syndrome type I (APS I) is an inherited recessive disorder with a progressive immunological destruction of many tissues including the adrenal cortex, the parathyroid glands, and the gonads. APS I is caused by mutations in the AIRE gene (autoimmune regulator), expressed in cells of the thymus and spleen, suggesting a role in central and peripheral tolerance. Aire(-/-) mice replicate the autoimmune features of APS I patients with the presence of multiple autoantibodies and lymphocytic infiltrates in various tissues, but young mice appear clinically healthy. We here report the investigation of 15- to 24-month-old Aire(-/-) mice. We did not observe any endocrinological abnormalities, nor did sera from these mice recognize known APS I autoantigens. Interestingly, however, there was a high frequency of marginal zone B-cell lymphoma in Aire(-/-) mice and liver infiltrates of B cells, suggesting chronic antigen exposure and exaggerated activation. Furthermore, increased numbers of monocytes in blood were identified as well as augmented numbers of metallophilic macrophages in the spleen. We propose that Aire, in addition to its function in the thymus, also has a peripheral regulatory role by controlling the development of antigen-presenting cells (APCs) and marginal zone B-cell activation.

Sentinel node lymphocytes: tumour reactive lymphocytes identified intraoperatively for the use in immunotherapy of colon cancer

The sentinel node is the first lymph node to receive lymphatic drainage from a tumour and is usually the first site of metastases. Today, the sentinel node is used for tumour staging. Here, we focus on its immunological role and investigate lymphocytic function in sentinel nodes, identified intraoperatively by peritumoural dye injection, from 15 patients with colon cancer. Tumour infiltrating lymphocytes, sentinel and nonsentinel lymph node cells and peripheral blood leukocytes were studied by flow cytometry, proliferation assays and interferon-γ secretion after activation with autologous tumour homogenate. Whereas tumour-infiltrating lymphocytes were nonresponsive in the proliferation assays, lymphocytes from sentinel nodes proliferated dose dependently and secreted interferon-γ upon stimulation with tumour homogenate. The responses were of varying magnitude and tended to be weaker in metastatic sentinel nodes. Sentinel node lymphocytes represents an enriched source of tumour reactive lymphocytes, and may be useful in future trials of adoptive immunotherapy.

Increased antigen presenting cell-mediated T cell activation in mice and patients without the autoimmune regulator

Patients with autoimmune polyendocrine syndrome type I (APS I)suffer from endocrine and non-endocrine disorders due to mutations in the autoimmune regulator gene (AIRE). Mouse Aire is expressed both in thymic medullary epithelial cells and in peripheral antigen-presenting cells, suggesting a role in both central and peripheral tolerance. We here report that Aire(-/-) dendritic cells (DC) activate naive T cells more efficiently than do Aire(+/+) DC. Expression array analyses of Aire(-/-) DC revealed differential regulation of 68 transcripts, among which, the vascular cell adhesion molecule-1 (VCAM-1) transcript was up-regulated in Aire(-/-) DC. Concurrently, the expression of the VCAM-1 protein was up-regulated on both Aire(-/-) DC and monocytes from APS I patients. Blocking the interaction of VCAM-1 prevented enhanced Aire(-/-) DC stimulation of T cell hybridomas. We determined an increased number of DC in spleen and lymph nodes and of monocytes in the blood from Aire(-/-) mice, and an increased number of blood monocytes in APS I patients. Our findings imply a role for Aire in peripheral DC regulation of T cell activation, and suggest that Aire participates in peripheral tolerance.

Eosinophil granulocytes are activated during the remission phase of ulcerative colitis

AIM

The aim of this study was to establish a method of investigating intestinal eosinophil and neutrophil granulocytes by flow cytometry, and to compare the distribution and activity of these cells in different stages of ulcerative colitis (UC).

METHODS

Biopsy samples were taken from six locations of the entire colon and from the terminal ileum in 10 patients with active total UC, 10 patients with inactive total UC, eight patients with active distal UC, and 11 control subjects. Cell suspensions from biopsies and from peripheral blood were incubated with fluorophore conjugated monoclonal antibodies. The use of scatter plot-gating and specific antibodies was established in a flow cytometry assay.

RESULTS

Eosinophils were more numerous and more active in patients with active UC than in controls. Interestingly, during inactive UC, the number of activated eosinophils was even larger. Eosinophil activity was high in the rectum of patients with distal colitis but was also slightly elevated in the proximal colon. Neutrophils were increased in number and activity during active but not inactive UC. In patients with distal colitis, activated neutrophils were only found in the sigmoid colon and rectum.

CONCLUSION

With this method, we confirm that neutrophils participate in the inflammatory process during active UC, and that they express a resting phenotype during remission. The finding of activated eosinophils in inflamed intestine strengthens the view of these cells as proinflammatory and tissue damaging. Nevertheless, our new finding of high eosinophil activation during inactive UC suggests that eosinophils play a role in repair of injured epithelium.

Detection of immune responses against urinary bladder cancer in sentinel lymph nodes

OBJECTIVE

The lymphatic drainage from a tumour is received in the sentinel node where the immune system encounters tumour derived antigens. We investigated anti-tumoural lymphocyte function in sentinel nodes from patients with urinary bladder cancer.

METHODS

In 14 patients undergoing cystectomy due to bladder cancer, radioactive tracer and blue dye were used to identify the sentinel node. Cell suspensions from the tumour, sentinel- and non-sentinel nodes and peripheral blood were analyzed by flow cytometry with antibodies against lymphocyte surface antigens and against the tumour cell marker cytokeratin-20. Reactivity against autologous tumour extract and the mitogen Concanavalin A was tested in proliferation assays with 3H-Thymidine incorporation. Lymphocytes were put in long-term culture with IL-2 and autologous tumour extract.

RESULTS

Sentinel nodes were detected in 12 of the 14 patients. Antigen dependent proliferation in response to autologous tumour extract was detected in 6 patients, in 5 cases in sentinel nodes, in the remaining case in a non-sentinel node. Proliferation against Concanavalin A was vigorous in lymph nodes from all patients, whereas tumour infiltrating lymphocytes were unresponsive. Lymphocytes from sentinel nodes could be expanded in vitro.

CONCLUSION

Tumour reactive lymphocytes are present in sentinel nodes draining human bladder cancers. These cells display immunologic function upon restimulation in vitro, and provide a promising source for expansion and subsequent adoptive T cell immunotherapy.

Analysis of T-cell receptor V beta gene repertoires after immune stimulation and in malignancy by use of padlock probes and microarrays

BACKGROUND

Detection of expanded T-cell clones, identified by their receptor (TCR) repertoires, can assist diagnosis and guide therapy in infectious, inflammatory, and autoimmune conditions as well as in tumor immunotherapy. Analysis of tumor-infiltrating lymphocytes often reveals preferential use of one or a few TCR V beta genes, compared with peripheral blood, indicative of a clonal response against tumor antigens.

METHODS

To simultaneously measure the relative expression of all V beta gene families, we combined highly specific and sensitive oligonucleotide reagents, called padlock probes, with a microarray read-out format. T-Cell cDNA was combined with a pool of V beta subfamily-specific padlock probes. Reacted probes were selectively amplified and the products hybridized to a microarray, from which the V beta subfamily distribution in each sample could be determined relative to a control sample.

RESULTS

In lymphocytes stimulated with the superantigen staphylococcal enterotoxin B, we detected expansions at the mRNA level of TCR subfamilies previously shown to respond to staphylococcal enterotoxin B. Expansions of the same V beta families could also be detected by flow cytometry. In samples from two bladder cancer patients, we detected predominant representations of specific V beta subfamilies in both tumor-infiltrating lymphocytes and in the draining lymph nodes, but not in non-tumor-draining lymph nodes or peripheral blood. Several expression profiles from draining lymph nodes in patients with malignant melanoma were divergent from profiles seen in non-tumor-draining lymph nodes.

CONCLUSION

Padlock probe-based parallel analysis of TCR V beta gene distributions provides an efficient method for screening multiple samples for T-cell clonal expansions with reduced labor and time of analysis compared with traditional methods.

Identification of sentinel nodes in patients with colon cancer

AIMS

Lymphatic mapping and sentinel node biopsy entails better staging in malignant melanoma and breast cancer and we used this technique in patients with colon cancer to possibly improve detection of lymphatic spread.

METHODS

Thirty patients with invasive adenocarcinomas were investigated. The tumour status in identified sentinel node(s) was compared with the status in all other harvested regional nodes for each patient. Patients were followed at regular visits for more than 30 months.

RESULTS

Sentinel nodes were identified in all cases, either per-operatively (28 cases) or at dissection of the formalin-fixed specimen (2 cases). The sentinel nodes were diagnostic for the entire lymphatic field in 28 patients and the false negative rate was 2/12. In four cases, the sentinel nodes were the only metastatic nodes. After at minimum 30 months, three patients had died of colon cancer metastases.

CONCLUSION

This method improved the identification of patients with lymph-node metastases, especially those with only few metastatic nodes. Patients dying from metastatic disease had lymph-node metastases at diagnosis.

[APS I--a severe autoimmune disease with endocrine and non-endocrine symptoms]

Autoimmune polyglandular syndrome type I (APS I) is an autosomal recessive disorder characterized by a combination of autoimmune manifestations affecting endocrine and non-endocrine organs. APS I usually presents in childhood. The three most common manifestations are chronic mucocutaneous candidiasis, hypoparathyroidism and Addison's disease. At least two of these must be present to fulfill the diagnostic criteria of this syndrome. The spectrum of other associated diseases includes gonadal insufficiency, alopecia, vitiligo and chronic active hepatitis. APS I is caused by a mutation in the AIRE-gene (autoimmune regulator) located on chromosome 21. Analysis of specific autoantibodies against intracellular enzymes, particularly enzymes in the synthesis of steroids and neurotransmittors, can be used in the diagnosis of APS I and to predict different manifestations of the disease.

Autoantibodies against 21-hydroxylase and side-chain cleavage enzyme in autoimmune Addison's disease are mainly immunoglobulin G1

OBJECTIVE

Immunoglobulin G (IgG) antibodies to the steroidogenic enzymes 21-hydroxylase (21OH) and side-chain cleavage enzyme (SCC) are important diagnostic markers for autoimmune Addison's disease and autoimmune polyendocrine syndromes (APS) types I and II. The characterization of autoantibody (IgG) subclasses may reveal information on how tIssue destruction takes place; therefore, IgG subtypes of anti-21OH and anti-SCC antibodies from sera of patients with Addison's disease, APS I and APS II were determined using recombinant 21OH and SCC.

METHODS

SCC(51-521) and his-SCC(51-521) were expressed by pET-scc in the Escherichia coli strain BL21 Star (DE3) and inclusion bodies were purified. Full-length, human 21OH fused to an N-terminal 6x histidine affinity tag was expressed in insect cells by using the baculovirus expression system bac-to-bac. Western blots were used to investigate the IgG subtype(s) of the autoantibodies against 21OH and SCC in patients and healthy blood donors.

RESULTS

All anti-SCC positive sera (n=10) contained autoantibodies of the IgG1 subclass, while four out of ten also contained IgG3. All anti-21OH positive sera (n=16) had autoantibodies exclusively against IgG1. Sera from 20 healthy subjects did not show any reactivity against 21OH or SCC.

CONCLUSIONS

The finding of a predominating IgG1 response against 21OH and SCC may suggest that T helper (Th) cells of the Th1 subclass are involved in destruction of the adrenal cortex in patients with autoimmune Addison's disease.

Analysis of H2-O influence on antigen presentation by B cells

HLA-DM (DM; in mouse H2-DM) promotes the exchange of MHC class II-associated peptides, resulting in the accumulation of stable MHC class II-peptide complexes. In naive (but not germinal center) B cells, a large part of DM is tightly associated with HLA-DO (DO; in mouse H2-O), but the functional consequence of this association for Ag presentation is debated. Here, we have extended previous studies by examining the presentation of multiple epitopes after Ag internalization by fluid phase endocytosis or receptor-mediated uptake by membrane Ig (mIg) receptors. We find that the effects of H2-O are more complex than previously appreciated; thus, while only minor influences on Ag presentation could be detected after fluid phase uptake, many epitopes were substantially affected after mIg-mediated uptake. Unexpectedly, the presentation of different epitopes was found to be enhanced, diminished, or unaffected in the absence of H2-O, depending on the specificity of the mIg used for Ag internalization. Interestingly, epitopes from the same Ag did not necessarily show the same H2-O dependency. This finding suggests that H2-O may control the repertoire of peptides presented by B cells depending on the mIg-Ag interaction. The absence of DO/H2-O from germinal center B cells suggests that this control may be released during B cell maturation.

RELP, a novel human REG-like protein with up-regulated expression in inflammatory and metaplastic gastrointestinal mucosa

We screened expressed sequence tag databases for genes with up-regulated expression in inflammatory bowel diseases. A gene encoding a regenerating protein (REG)-like protein called RELP was identified and characterized. The relp gene encodes a major transcript of 1518 nucleotides, and two truncated splice variants. Unlike the reg genes, which form a cluster in chromosome 2, relp maps to chromosome 1p12-13.1. The predicted translation product is a 158-amino acid preprotein, showing 43% to 47% similarity to the REG proteins. It contains a 22-amino acid signal peptide, and a conserved calcium-dependent carbohydrate-recognition domain. Complementary DNA for the orthologous mouse gene was also cloned. The RELP protein is constitutively expressed in epithelial neuroendocrine cells of the small intestine and in parietal cells of the gastric mucosa. An up-regulated expression of RELP was seen in epithelial cells of inflammatory mucosa in ulcerative colitis and Crohn's disease, in regenerating epithelial borders of gastric ulcers, and in metaplastic epithelium in the antrum and the esophagus. Our findings suggest that RELP might be involved in inflammatory and metaplastic responses of the gastrointestinal epithelium.

Autoantibodies to alpha-fodrin in primary Sjögren's syndrome and SLE detected by an in vitro transcription and translation assay

OBJECTIVE

To investigate the prevalence of alpha-fodrin autoantibodies in primary Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE) with and without secondary SS, using an in vitro transcription and translation assay (ITT).

METHODS

cDNA encoding JS-1, the amino-terminal portion of alpha-fodrin, was used for ITT. Immunoprecipitation was performed with sera from 56 primary SS patients and 67 SLE patients, 14 with and 53 without secondary SS. Correlations to RF, ANA, anti-dsDNA, anti-SS-A and anti-SS-B antibodies, hypergammaglobulinemia, labial salivary gland biopsy grade, extraglandular manifestations and a modified SLE disease activity index (mSLEDAI) were made.

RESULTS

Autoantibodies against alpha-fodrin were detected in 16/56 (29%) of primary SS patients and in 25/53 (47%) of sera from SLE patients without secondary SS. In SLE patients with secondary SS the prevalence was 3/14 (21%). None of the blood donors showed alpha-fodrin reactivity. Correlations were found to RF, ANA, anti-dsDNA antibodies and a positive mSLEDAI score.

CONCLUSION

The frequency of alpha-fodrin autoantibodies detected by this method is similar in sera from primary SS patients and SLE patients with or without secondary SS. The presence of alpha-fodrin autoantibodies seems to reflect non-organ-specific autoimmunity in primary SS and SLE and to be of limited discriminating value.

Aire deficient mice develop multiple features of APECED phenotype and show altered immune response

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a monogenic autosomal recessive disease caused by mutations in the AIRE gene. Here we have produced knock-out mice for the Aire gene. The Aire-/- mice develop normally; however, autoimmune features of APECED in Aire-/- mice are evident, including multiorgan lymphocytic infiltration, circulating autoantibodies and infertility. The distribution of B and T cells and thymic maturation as well as activation of T cells appear normal, while the TCR-Vbeta repertoire is altered in peripheral T cells of Aire-/- mice. When mice are challenged with immunization, the peripheral T cells of Aire-/- mice have a 3-5-fold increased proliferation. These findings suggest that the Aire gene is not necessary for normal T cell education and development, while a defect in immune response detected in challenged Aire-/- mice underlines the crucial role of AIRE/Aire in maintaining homeostatic regulation in the immune system.

Impaired immunoproteasome assembly and immune responses in PA28-/- mice

In vitro PA28 binds and activates proteasomes. It is shown here that mice with a disrupted PA28b gene lack PA28a and PA28b polypeptides, demonstrating that PA28 functions as a hetero-oligomer in vivo. Processing of antigenic epitopes derived from exogenous or endogenous antigens is altered in PA28-/- mice. Cytotoxic T lymphocyte responses are impaired, and assembly of immunoproteasomes is greatly inhibited in mice lacking PA28. These results show that PA28 is necessary for immunoproteasome assembly and is required for efficient antigen processing, thus demonstrating the importance of PA28-mediated proteasome function in immune responses.