HLA class II induction in human islet cells by interferon-gamma plus tumour necrosis factor or lymphotoxin

Cathepsin S inhibitor prevents autoantigen presentation and autoimmunity

The cysteine endoprotease cathepsin S mediates degradation of the MHC class II invariant chain Ii in human and mouse antigen-presenting cells. Studies described here examine the functional significance of cathepsin S inhibition on autoantigen presentation and organ-specific autoimmune diseases in a murine model for Sjögren syndrome. Specific inhibitor of cathepsin S (Clik60) in vitro markedly impaired presentation of an organ-specific autoantigen, 120-kDa alpha-fodrin, by interfering with MHC class II-peptide binding. Autoantigen-specific T cell responses were significantly and dose-dependently inhibited by incubation with Clik60, but not with inhibitor s of cathepsin B or L. Clik60 treatment of mouse salivary gland cells selectively inhibited autopeptide-bound class II molecules. Moreover, the treatment with Clik60 in vivo profoundly blocked lymphocytic infiltration into the salivary and lacrimal glands, abrogated a rise in serum autoantibody production, and led to recovery from autoimmune manifestations. Thus, inhibition of cathepsin S in vivo alters autoantigen presentation and development of organ-specific autoimmunity. These data identify selective inhibition of cysteine protease cathepsin S as a potential therapeutic strategy for autoimmune disease processes.

Polymorphisms of interferon-gamma gene CA-repeat and interleukin-10 promoter region (-592A/C) in Japanese type I diabetes

We investigated the association of the polymorphisms of interferon-gamma gene (IFNG) CA-repeat and IL-10-592A/C with clinical heterogeneity of type I diabetes as well as susceptibility to type I diabetes. Two hundred seven Japanese type I diabetic patients and 160 healthy control subjects were studied in this case-control study. No significant differences of global IFNG allele frequencies were found between controls and type I diabetic patients, and between each subgroup of the patients and controls. When compared with controls, the a12 allele was increased in the patients with age at onset <25 years (p 0.0241, p(c) = 0.1205), and a significant increased frequency of the a12 positive genotype was observed in the patients with age at onset <25 years (p(c) = 0.0121). There were no differences of IL-10-592 genotype and allele frequencies between controls and type I diabetes. However, the frequency of the -592*C allele was significantly increased in the patients with highly positive-GADab compared with controls (p(c) = 0.0060) or compared with the GADab-negative type I patients (p(c) = 0.0276). These results suggest that the IFNG CA-repeat and the IL-10-592A/C polymorphisms are not strong determinants of susceptibility to the development of type I diabetes in Japanese individuals. However, both the IFNG CA-repeat and the IL-10-592A/C polymorphisms are associated with clinical heterogeneity in type I diabetes.

Tumor necrosis factor receptor p55 and p75 deficiency protects mice from developing experimental autoimmune myasthenia gravis

The precise pathogenic role of proinflammatory cytokines belonging to the tumor necrosis factor (TNF) family has not been investigated yet in antibody-mediated myasthenia gravis (MG) and experimental autoimmune myasthenia gravis (EAMG). In this study we report that TNF receptor p55(-/-) p75(-/-) mice were resistant to the development of clinical EAMG induced by acetylcholine receptor (AChR) immunizations. The resistance was associated with reduced serum levels of IgG, IgG(1), IgG(2a), and IgG(2b) anti-AChR antibody isotypes. However, IgM anti-AChR antibodies were not reduced, suggesting defective anti-AChR IgG class switching in TNF receptor p55(-/-) p75(-/-) mice. We thus demonstrate the genetic evidence for the role of TNF receptor p55 and p75 in EAMG pathogenesis, and their requirement for the generation of anti-AChR IgG antibodies.

Vaccines and the risk of insulin-dependent diabetes (IDDM): potential mechanism of action

Immunization with a number of different vaccines, including live and killed vaccines, has been linked to the development of insulin-dependent (type 1) diabetes in humans and animals. Multiple different mechanisms have been proposed to explain the association between vaccines and diabetes. The current paper reviews multiple different mechanisms by which vaccines are known to manipulate the immune system and can induce an autoimmune disease such as type 1 diabetes. Genetic variability may determine which of these pathways, or possible other pathways, predominate in an individual following immunization.

IL-2-induced tumor necrosis factor (TNF)-beta expression: further analysis in the IL-2 knockout model, and comparison with TNF-alpha, lymphotoxin-beta, TNFR1 and TNFR2 modulation

IL-2 induces the stimulation of inflammatory and immune reactions, and the apoptosis of antigen-activated cells. However, the molecular basis of these pleiotropic functions is largely unknown. We have previously reported that IL-2 induces genes involved in cytoskeleton organization, oncogene regulation and transcriptional control. In an IL-2-dependent cell line, we have also shown that IL-2 induces tumor necrosis factor (TNF)-beta mRNA through the Jak-STAT pathway. Here, we first demonstrate in vitro that IL-2 induces mature and partially spliced TNF-beta mRNA in the splenocytes and lymph node cells of both IL-2(-/-) and IL-2(+/-) mice. Under the same experimental conditions, IL-2 is seen to induce TNF-alpha mRNA. mRNA expression is followed by semiquantitative RT-PCR and this analysis is then extended in vivo by studying different lymphoid organs from IL-2(-/-)animals. Strikingly, the expression of TNF-beta mRNA is noted to be extremely low in the spleens and lymph nodes of IL-2(-/-) mice. Similarly, TNF-alpha, lymphotoxin (LT)-beta, TNFR1 and TNFR2 mRNA levels are also low in the spleens of IL-2(-/-) animals, whereas IFN-gamma and IL-4 mRNA levels remain unaffected in these animals. The experimental values are significantly different (P < or = 0.05) from those of control IL-2(+/-) animals. Western blot analysis of TNF-alpha expression confirmed and extended the results at the protein level. For the first time, we demonstrate that IL-2 directly or indirectly regulates genes of the TNF-TNFR family in secondary lymphoid organs. Furthermore, IL-2(-/-) animals in which thymopoiesis is unaffected show normal expression of these genes. Altogether, our data further define the pleiotropic effects of IL-2 at the molecular level.

Control of target cell survival in thyroid autoimmunity by T helper cytokines via regulation of apoptotic proteins

After autoimmune inflammation, interactions between CD95 and its ligand (CD95L) mediate thyrocyte destruction in Hashimoto's thyroiditis (HT). Conversely, thyroid autoimmune processes that lead to Graves' disease (GD) result in autoantibody-mediated thyrotropin receptor stimulation without thyrocyte depletion. We found that GD thyrocytes expressed CD95 and CD95L in a similar manner to HT thyrocytes, but did not undergo CD95-induced apoptosis either in vivo or in vitro. This pattern was due to the differential production of TH1 and TH2 cytokines. Interferon gamma promoted caspase up-regulation and CD95-induced apoptosis in HT thyrocytes, whereas interleukin 4 and interleukin 10 protected GD thyrocytes by potent up-regulation of cFLIP and Bcl-xL, which prevented CD95-induced apoptosis in sensitized thyrocytes. Thus, modulation of apoptosis-related proteins by TH1 and TH2 cytokines controls thyrocyte survival in thyroid autoimmunity.

Coreceptor restriction within the HLA-DQ locus for Epstein-Barr virus infection

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that causes infectious mononucleosis and is etiologically associated with malignancies of multiple origins. EBV enters cells through a cascade of interactions between its envelope glycoprotein gp350 and the gp42-gH-gL complex with cellular receptors. Membrane fusion is catalyzed by the binding of gp42, a member of the C type lectin family, to HLA class II molecule HLA-DR, -DP, or -DQ. Here we demonstrate that only a subset of HLA-DQ alleles mediates EBV entry, indicating that individuals expressing these alleles may offer unique sites for EBV infection and subsequent sequelae. Additionally, the specific site within HLA-DQ determined to be essential for EBV entry is homologous to a site within MHC class I shown by structural studies to bind to the C type-lectin-like natural killer receptor, providing insight into the biochemical nature of the gp42-HLA class II interaction.

Human TNF can induce nonspecific inflammatory and human immune-mediated microvascular injury of pig skin xenografts in immunodeficient mouse hosts

TNF activates endothelial cells to express cell surface molecules that are necessary to recruit a local infiltrate of leukocytes. Because the actions of this proinflammatory cytokine are not species restricted, we investigated whether human TNF can up-regulate porcine endothelial adhesion molecules to elicit human T cell infiltration and damage of pig skin xenografts in a chimeric immunodeficient mouse model. We have previously demonstrated the vigorous rejection of human skin allografts and the absence of injury to porcine skin xenografts in human PBMC-SCID/beige mice. Intradermal administration of human TNF at high doses (600 or 2000 ng) caused nonspecific inflammatory damage of pig skin grafts, whereas low concentrations of TNF (60 or 200 ng) resulted in human PBMC-dependent injury of porcine endothelial cells. There was a strong correlation among pig skin xenograft damage, human T cell infiltration, and the TNF-induced up-regulation of swine MHC class I and class II molecules, VCAM-1, and, in particular, the de novo expression of porcine E-selectin. The microvascular damage and leukocytic infiltration elicited by TNF were enhanced by porcine IFN-gamma, suggesting that xenografts may be less prone to cytokine-mediated injury due to the species-restricted effects of recipient IFN-gamma. Our results indicate that maintenance of a quiescent endothelium, which does not express E-selectin or other activation-dependent adhesion molecules, is important in preventing human anti-porcine T cell xenoresponses in vivo and that TNF signaling molecules and TNF-responsive gene products are appropriate therapeutic targets to protect against human T cell-mediated rejection of pig xenografts.

Defective tumour necrosis factor-alpha production in mother's milk is related to cow's milk allergy in suckling infants

BACKGROUND

The precise role of leucocytes in human milk is still unresolved.

OBJECTIVE

To assist in clarifying the immune mechanisms involved in the development of CMA in suckling infants, we studied the role of immunoregulatory leucocytes and their mediators in human breast milk.

METHODS

The study population consisted of 43 lactating mothers and their infants, aged 0.25-8.0 months, followed-up prospectively from birth. Of these mothers, 27 had an infant with challenge-proven cow's milk allergy manifested with either skin (n = 23), gastrointestinal (n = 2) or skin and gastrointestinal symptoms (n = 3). Sixteen mothers with a healthy infant served as controls. We evaluated the spontaneous and mitogen-induced tumour necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) production of human milk leucocytes and isolated peripheral blood lymphocytes in vitro with a commercial ELISA kit.

RESULTS

TNFalpha production of breast milk leucocytes was significantly lower in the mothers with a cow's milk-allergic infant, whereas IFNgamma production of these cells was comparable in the two groups.

CONCLUSION

Our results suggest that in the breast milk of mothers having an infant with cow's milk allergy, the number and function of TNFalpha-producing cells is defective. This might lead to a disturbance in the development of oral tolerance and thereby to the development of CMA in suckling infants. These novel results may help in clarifying the etiopathogenesis of CMA.

Immunopathogenesis of hepatitis B virus recurrence after liver transplantation

BACKGROUND AND AIMS

Hepatitis B virus (HBV) recurrence after orthotopic liver transplantation is associated with inflammatory graft changes, despite immunosuppression and donor/recipient HLA mismatch. We investigated whether immune mechanisms are involved in the pathogenesis of hepatitis B after liver transplantation.

METHODS

The virus-specific T helper (Th) cell response, activation of Th1/Th2 subpopulations, donor/recipient HLA, and expression of tumor necrosis factor (TNF)-alpha/TNF receptors were determined in 28 patients who underwent transplantation for HBV-related cirrhosis (17 with HBV recurrence and 11 without recurrence) in comparison to 30 nontransplant patients with chronic hepatitis B.

RESULTS

Orthotopic liver transplantation recipients with HBV recurrence showed significant hepatitis B core antigen-specific T-cell proliferation, comparable to nontransplant patients, which was not present in transplant recipients without recurrence. In addition, hepatic and serum interleukin (IL)-2, interferon-gamma, and TNF-alpha were enhanced, without changes in IL-4 and IL-10. Phenotypically, hepatic infiltrates in allografts with HBV recurrence were comprised of CD4+ lymphocytes and macrophages with a correlation between interferon-gamma- and TNF-alpha-producing cells and the degree of necroinflammatory activity. There was a marked up-regulation of both TNF-alpha receptors, significantly greater than in nontransplant patients.

CONCLUSIONS

These findings suggest that despite immunosuppression, HLA class I-independent immune mechanisms have a significant pathogenic role in liver damage associated with HBV recurrence after liver transplantation.

A Defective Protein Kinase C Anchoring System Underlying Age-Associated Impairment in TNF-α Production in Rat Macrophages

The ability of macrophages to secrete cytokines is important in host responses to infections inflammatory stimuli, both of which are altered with aging. In this study, age-associated changes in the release of TNF-α from LPS-stimulated rat alveolar macrophages were determined and correlated with a decrease in the level of RACK1, the anchoring protein involved in protein kinase C translocation and activation. Macrophages from aged rats produced ∼50% less TNF-α than those from young rats. This effect was observed independently from the concentration of LPS used and the time considered. The decrease observed was associated with a defective PKC translocation, due to a reduction in the expression of RACK1, whereas no differences were detected in the expression of LPS receptor (CD14) or total PKC isoforms (α and βΙΙ) in old and young rats. Use of RACK1 antisense oligonucleotide reduced the ability of young macrophages to respond to LPS, further supporting the idea that a deficit in RACK1 contributes to the functional impairment in aged macrophages and that age-induced macrophage immunodeficiencies are associated with alteration in signal transduction pathways.

HLA microsatellite associations with insulin-dependent diabetes mellitus in Singaporean Chinese

Singaporean Chinese with insulin-dependent diabetes mellitus (IDDM) have previously been shown to be associated with the DRB1*0301 haplotype and the joint occurrence of DRB1*0301/*0901 and DRB1*0301/*04. The present study extended previous HLA associations by investigating the HLA region using four microsatellites (TNFa, D6S273, TAP1, DQCARII). Seventy-five IDDM patients and 80 healthy controls were studied. TNFa*3 (RR = 2.26), TNFa*12 (RR = 3.30), TAP1*9 (RR = 2.55) showed increased frequencies while TNFa*11 (RR = 0.29), TAP1*4 (RR = 0.50) showed decreased frequencies in patients compared to controls. Linkage analysis suggested that the positive associations of TNFa*3 and TAP1*9 were secondary to that of DRB1*0301. However, TNFa*12 appeared to provide additional risks to IDDM besides the DRB1*0301 haplotype, whereas TNFa*11 and TAP1*4 conferred an independent protective effect against IDDM. Our findings reinforce the notion that susceptibility to and protection against IDDM may include TNF region. In the present study, TNFa*12 seemed to be the primary association in the DRB1*0405 haplotype and may play an independent role in the pathogenesis of IDDM through TNF-alpha function.

Inhibition of tumor necrosis factor-alpha (TNF-alpha)/TNF-alpha receptor binding by structural analogues of suramin

Suramin, a symmetrical polysulfonated urea derivative, promotes the dissociation of trimeric human tumor necrosis factor-alpha (TNF-alpha) into biologically inactive subunits and prevents the interaction of TNF-alpha with its cellular receptors. The aim of this work was to identify compounds structurally related to suramin which inhibit the binding of TNF-alpha to its receptor. Molecular modeling studies were performed on suramin and TNF-alpha molecules and likely interaction sites were identified in the docked complex. On this basis, Evans blue, trypan blue, sulfonazo III, beryllon II, and 1,3,6-naphthalenetrisulfonic acid trisodium salt were identified as polysulfonated compounds endowed, to various extents, with the structural characteristics responsible for interaction with TNF-alpha. N,N-bis(3,5-di-tert-butylphenyl)-3,4,9,10-perylenedicarboximide was used as an unrelated structure. The capacity of these molecules to inhibit the binding of TNF-alpha with its receptor p55 was tested in vitro by means of a specific immunoenzymatic assay using suramin as reference compound. Evans blue and trypan blue inhibited TNF-alpha/p55 binding with an IC50 of 0.75 and 1.00 mM, respectively (suramin IC50: 0.65 mM); no effect was observed with the other molecules. Molecular modeling analyses on Evans blue and trypan blue docked into the TNF-alpha molecule support these experimental results by demonstrating that these compounds share with suramin a similar binding mode to TNF-alpha. The results of this work provide a new insight into and useful hints for the design of new chemical entities endowed with a potent and selective activity on TNF-alpha.

Genetic polymorphisms at the tumour necrosis factor loci (TNFA and TNFB) in cardiac sarcoidosis

Many studies have previously confirmed high TNFalpha (tumor necrosis factor-alpha) production in sarcoidosis, and have shown that TNFalpha plays an important role in granuloma formation. We investigated TNFA and TNFB (lymphotoxin-alpha) gene polymorphisms in 26 cardiac sarcoidosis patients of Japanese origin. These studies revealed a significant increase in the more uncommon TNFA2 allele in the patient group, suggesting that the TNFA gene controls the genetic susceptibility to cardiac sarcoidosis.

The effect of anaesthesia and surgery on plasma cytokine production

The aim of this study was to investigate cytokine production in response to anaesthesia [total intravenous anaesthesia (TIVA) with propofol, sufentanil and atracurium] and surgery (laparoscopic vs. open cholecystectomy). Forty adult patients, ASA I-II, undergoing elective laparoscopic (group 1) or open (group 2) cholecystectomy were studied. Venous blood samples for measurement of interleukin (IL)-1beta, IL-2, IL-4, IL-6, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were taken before the induction of anaesthesia, pre-incisionaly, at the end of anaesthesia and surgery and 24-h postoperatively. Pre-incisionaly, in both groups, IL-1beta, IL-4, IL-6, TNF-alpha and IFN-gamma did not show a significant change, whereas IL-2 showed a significant decrease (p < 0.005 in group 1 and p < 0.001 in group 2) compared with pre-induction levels. By the end of anaesthesia and surgery, IL-1beta, IL-2, IL-4, IL-6 and TNF-alpha showed a significant increase in group 2 (p < 0.005 for IL-1beta, IL-2 and IL-4, and p < 0.05 for IL-6 and TNF-alpha); while in group 1, only IL-2 showed a significant increase (p < 0.01) and IFN-gamma showed a significant decrease (p < 0.05) compared with pre-incisional levels. By 24-h postoperatively, IL-1beta, IL-4, IL-6 and TNF-alpha had decreased significantly in group 2 (p < 0.005 for IL-4 and p < 0.05 for the others); whereas in group 1, IL-2 and IFN-gamma showed a significant increase (p < 0.005) compared with the end of anaesthesia and surgery level. In conclusion, TIVA with propofol, sufentanil and atracurium does not seem to have a significant effect on IL-1beta, IL-4, IL-6, TNF-alpha and IFN-gamma release. IL-2 was the only cytokine to show a significant decrease due to the effect of anaesthesia alone in both groups. The cytokine response to open cholecystectomy stimulated both the pro-inflammatory (IL-1beta, IL-6 and TNF-alpha) and the anti-inflammatory (IL-4) components, while this response was absent in laparoscopic cholecystectomy.

In autoimmune diabetes the transition from benign to pernicious insulitis requires an islet cell response to tumor necrosis factor alpha

The islet-infiltrating and disease-causing leukocytes that are a hallmark of insulin-dependent diabetes mellitus produce and respond to a set of cytokine molecules. Of these, interleukin 1beta, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma are perhaps the most important. However, as pleiotropic molecules, they can impact the path leading to beta cell apoptosis and diabetes at multiple points. To understand how these cytokines influence both the formative and effector phases of insulitis, it is critical to determine their effects on the assorted cell types comprising the lesion: the effector T cells, antigen-presenting cells, vascular endothelium, and target islet tissue. Here, we report using nonobese diabetic chimeric mice harboring islets deficient in specific cytokine receptors or cytokine-induced effector molecules to assess how these compartmentalized loss-of-function mutations alter the events leading to diabetes. We found that islets deficient in Fas, IFN-gamma receptor, or inducible nitric oxide synthase had normal diabetes development; however, the specific lack of TNF- alpha receptor 1 (p55) afforded islets a profound protection from disease by altering the ability of islet-reactive, CD4(+) T cells to establish insulitis and subsequently destroy islet beta cells. These results argue that islet cells play a TNF-alpha-dependent role in their own demise.

Type 1 diabetes: the facts fit a deficient inhibitory signal given by MHC class II

This paper presents a hypothesis regarding the aetiology of Type 1 (autoimmune) diabetes, which suggests that autoimmunity is normally prevented by an inhibitory or negative signal delivered by MHC molecules, and that in Type 1 diabetes it is the inability of beta cells to deliver sufficient negative signal from MHC Class II that drives the underlying autoimmune process. Based on a broad survey of the diabetes literature, a list of clinical, pathological, experimental and epidemiological 'facts' about Type 1 diabetes is presented which are considered to be widely accepted as proven. The new theory is then compared to other recent theories on the aetiology of diabetes with regard to its ability to explain these accepted 'facts'.

Expression of Fas-Fas ligand antigens and apoptotic marker APO2.7 by the human conjunctival epithelium. Positive correlation with class II HLA DR expression in inflammatory ocular surface disorders

Fas antigen (CD95) is a membrane receptor that plays a major role in induction of apoptosis. In surface conjunctival epithelial cells the expressions of Fas, Fas ligand, the apoptotic marker APO2.7 and of HLA DR class II antigen, a membrane marker known to be expressed in inflammatory conditions were investigated. Impression cytology specimens were collected in 65 patients: 20 normal ones, 15 contact lens wearers, 20 receiving chronic topical antiglaucoma treatment and 10 with nonspecific chronic conjunctivitis. Cells were processed for flow cytometry, using monoclonal antibodies to Fas, Fas ligand, APO2.7, HLA DR antigens and a negative isotypic control. Percentages of positive cells were recorded and levels of fluorescence quantified using fluorescent beads at standardized fluorescence intensities. In addition, a human conjunctival cell line was incubated with anti-Fas stimulating antibodies in order to test Fas-induced apoptosis in vitro. Fas was found in all specimens in most of the conjunctival cells, but quantitation of levels of fluorescence showed a significantly higher expression in pathologic eyes than in normal ones. Fas ligand and APO2.7 were variably expressed by conjunctival cells, but in a significantly higher percentage of cells in pathological eyes than in normal ones. In these eyes a strong expression of HLA DR was also observed, whereas normal eyes showed lowest levels. Highly significant correlations were found between Fas, Fas ligand, APO2.7 and HLA DR levels. Anti-Fas antibodies in vitro induced strong apoptosis in epithelial cells as confirmed by APO2.7 expression and DAPI staining. This study confirms that conjunctival epithelial cells normally express Fas antigen, and more inconstantly its ligand, as do corneal ones or keratinocytes. Fluorescence quantitation by flow cytometry showed much higher expression in inflammatory eyes than in normal ones, and demonstrated a strong correlation between apoptotic and inflammatory pathways in the ocular surface.

Myasthenia gravis and tumor necrosis factor beta polymorphisms: linkage disequilibrium but no association beyond HLA-B8

Tumor necrosis factor (TNF) may contribute to the susceptibility for autoimmune diseases. We examined TNFbeta gene polymorphisms detected by AspHI and NcoI digestion of genomic DNA in patients with myasthenia gravis (n=105) and healthy controls (n=114). In both groups, the frequencies of TNFbeta alleles were not different. AspHI and NcoI polymorphisms of TNFbeta showed a strong association with HLA-B8 (p < 0.03 resp. p < 0.0001 for AspHI and Ncol) both in patients and controls. Our results imply linkage disequilibrium of TNFbeta alleles with HLA-B8 and in myasthenia gravis we were unable to show a stronger association beyond HLA-B8.

Protective role of gamma interferon during the recall response to influenza virus

During secondary immune responses to influenza virus, virus-specific T memory cells are a major source of gamma interferon (IFN-gamma). We assessed the contribution of IFN-gamma to heterologous protection against the A/WSN/33 (H1N1) virus of wild-type and IFN-gamma-/- mice previously immunized with the A/HK/68 (H3N2) virus. The IFN-gamma-/- mice displayed significantly reduced survival rates subsequent to a challenge with various doses of the A/WSN/33 virus. This was associated with an impaired ability of the IFN-gamma-/- mice to completely clear the pulmonary virus by day 7 after the challenge, although significant reduction of the virus titers was noted. However, the IFN-gamma-/- mice developed type A influenza virus cross-reactive cytotoxic T lymphocytes (CTLs) similar to the wild-type mice, as demonstrated by both cytotoxicity and a limiting-dilution assay for the estimation of CTL precursor frequency. The pulmonary recruitment of T cells in IFN-gamma-/- mice was not dramatically affected, and the percentage of CD4(+) and CD8(+) T cells was similar to that of wild-type mice. The T cells from IFN-gamma-/- mice did not display a significant switch toward a Th2 profile. Furthermore, the IFN-gamma-/- mice retained the ability to mount significant titers of WSN and HK virus-specific hemagglutination-inhibiting antibodies. Together, these results are consistent with a protective role of IFN-gamma during the heterologous response against influenza virus independently of the generation and local recruitment of cross-reactive CTLs.

Hypotheses on the role of cytokines in peptic ulcer disease

Helicobacter pylori is the cause of chronic type B gastritis and occurs in almost all patients with duodenal ulcers. Infection with H. pylori is characterized by an increased production of several inflammatory cytokines. Increasing evidence suggests a central role of these cytokines in the pathogenesis of H. pylori-associated gastritis and peptic ulcer disease. Cytokines may be crucial in the recruitment and activation of inflammatory cells and in stimulation of gastrin release. In addition to their proinflammatory properties, cytokines may also inhibit the ulcer occurrence by stimulation of prostaglandins and somatostatin release and by direct impairment of acid secretion. The balance of these factors may determine the clinical outcome of H. pylori infection.

Effects of interferon-gamma and tumor necrosis factor alpha on the expression of the genes encoding aggrecan, biglycan, and decorin core proteins in cultured human chondrocytes

OBJECTIVE

To determine the effects of interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha), alone or in combination, on the expression of aggrecan, biglycan, and decorin core protein genes in human chondrocytes.

METHODS

Isolated human chondrocytes were cultured on poly(2-hydroxyethyl methacrylate)-coated plastic dishes to prevent the loss of cartilage-specific phenotype, and the effects of IFN gamma and TNF alpha, alone or in combination, on aggrecan, biglycan, and decorin core protein gene transcription and steady-state messenger RNA (mRNA) levels were examined.

RESULTS

The addition of IFN gamma (1.5 pM) or TNF alpha (0.3 pM) caused a decrease in the steady-state level of aggrecan mRNA (-25% and -15%, respectively), and the combination of these low-concentration cytokines caused a potent inhibition (-66%). These effects were the result of a decrease (-50%) in the transcription rate of the corresponding gene. At the concentrations used, IFN gamma did not alter the levels of biglycan mRNA or the transcription rates of the biglycan core protein gene. In contrast, TNF alpha decreased biglycan steady-state mRNA levels (-62%) and the biglycan core protein gene transcription rate (-18%). The combination of IFN gamma and TNF alpha resulted in a potentiation of the inhibitory effects of TNF alpha on biglycan mRNA levels (-79%) and transcription rate of the biglycan core protein gene (-46%). IFN gamma produced a modest decrease in decorin mRNA levels (-23%) and decorin core protein gene transcription rate (-17%). In contrast, TNF alpha resulted in a marked increase in decorin mRNA levels (+260%) that was not the result of transcriptional regulation. Notably, the combination of IFN gamma and TNF alpha potentiated the inhibitory effects of IFN gamma on decorin mRNA (-80%) and on the transcription of the corresponding gene (-43%). Similar results were obtained in fetal and adult articular chondrocytes.

CONCLUSION

These data demonstrate that 1) the expression of the core protein genes encoding the cartilage proteoglycans aggrecan, biglycan, and decorin is differentially regulated by IFN gamma and TNF alpha; 2) these effects are mediated by transcriptional and posttranscriptional mechanisms; and 3) the combination of the 2 cytokines causes a potent inhibitory effect on the expression of the genes for the core proteins of these 3 proteoglycans, which occurs largely at the transcriptional level. The inhibition of aggrecan, decorin, and biglycan core protein gene expression by the combination of IFN gamma and TNF alpha may contribute to the cartilage destruction that is characteristic of inflammatory joint diseases.

Effects of interferon-gamma and tumor necrosis factor alpha on the expression of the genes encoding aggrecan, biglycan, and decorin core proteins in cultured human chondrocytes

OBJECTIVE

To determine the effects of interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha), alone or in combination, on the expression of aggrecan, biglycan, and decorin core protein genes in human chondrocytes.

METHODS

Isolated human chondrocytes were cultured on poly(2-hydroxyethyl methacrylate)-coated plastic dishes to prevent the loss of cartilage-specific phenotype, and the effects of IFN gamma and TNF alpha, alone or in combination, on aggrecan, biglycan, and decorin core protein gene transcription and steady-state messenger RNA (mRNA) levels were examined.

RESULTS

The addition of IFN gamma (1.5 pM) or TNF alpha (0.3 pM) caused a decrease in the steady-state level of aggrecan mRNA (-25% and -15%, respectively), and the combination of these low-concentration cytokines caused a potent inhibition (-66%). These effects were the result of a decrease (-50%) in the transcription rate of the corresponding gene. At the concentrations used, IFN gamma did not alter the levels of biglycan mRNA or the transcription rates of the biglycan core protein gene. In contrast, TNF alpha decreased biglycan steady-state mRNA levels (-62%) and the biglycan core protein gene transcription rate (-18%). The combination of IFN gamma and TNF alpha resulted in a potentiation of the inhibitory effects of TNF alpha on biglycan mRNA levels (-79%) and transcription rate of the biglycan core protein gene (-46%). IFN gamma produced a modest decrease in decorin mRNA levels (-23%) and decorin core protein gene transcription rate (-17%). In contrast, TNF alpha resulted in a marked increase in decorin mRNA levels (+260%) that was not the result of transcriptional regulation. Notably, the combination of IFN gamma and TNF alpha potentiated the inhibitory effects of IFN gamma on decorin mRNA (-80%) and on the transcription of the corresponding gene (-43%). Similar results were obtained in fetal and adult articular chondrocytes.

CONCLUSION

These data demonstrate that 1) the expression of the core protein genes encoding the cartilage proteoglycans aggrecan, biglycan, and decorin is differentially regulated by IFN gamma and TNF alpha; 2) these effects are mediated by transcriptional and posttranscriptional mechanisms; and 3) the combination of the 2 cytokines causes a potent inhibitory effect on the expression of the genes for the core proteins of these 3 proteoglycans, which occurs largely at the transcriptional level. The inhibition of aggrecan, decorin, and biglycan core protein gene expression by the combination of IFN gamma and TNF alpha may contribute to the cartilage destruction that is characteristic of inflammatory joint diseases.

Cytokine gene expression in pancreatic islet grafts in the rat

We examined the production of cytokine message in allogeneic and syngeneic rat pancreatic islet grafts using specific primers and polymerase chain reaction. Freshly isolated islet preparations contained transcripts for interleukin (IL)-1alpha, IL-6, IL-10, and interferon-gamma (IFN-gamma) but not for IL-2. IL-1alpha in allogeneic grafts showed increased and consistently high expression from 1 to 7 days after transplantation, but the level in syngeneic grafts fell quickly to pretransplant levels. IL-2 and IFN-gamma transcripts were found in allogeneic grafts at 1, 3, 5, and 7 days after transplantation with a peak at day 5, but these cytokines were almost absent from syngeneic grafts. The peak of IL-6 expression was 1 day after transplantation in both syngeneic and allogeneic grafts, and then the level fell quickly. IL-10 was produced at approximately the same high level at all time points in both syngeneic and allogeneic grafts. The results show that freshly isolated islet preparations contain IL-1alpha, IL-6, IL-10, and IFN-gamma transcripts at the time of transplantation. The initial production of cytokines in islet grafts, especially IL-1, may explain phenomena such as graft nonfunction, rapid rejection, and lack of response to immunosuppression.

Proteasome subunits, low-molecular-mass polypeptides 2 and 7 are hyperexpressed by target cells in autoimmune thyroid disease but not in insulin-dependent diabetes mellitus: implications for autoimmunity

Autoimmune thyroid diseases (AITD) and insulin-dependent diabetes mellitus (IDDM) are two autoimmune syndromes of unknown etiology with common immune features. One is that the target cells, thyrocytes and pancreatic islet beta cells respectively, hyperexpress several proteins encoded in the HLA region: HLA class I, HLA class II and transporter associated with antigen processing (TAP-1): the clinical course and many aspects of the immunopathology are, however, quite different. Low-molecular-mass polypeptides 2 and 7 (LMP2 and LMP7) are proteasome subunits that increase the efficiency of endogenous antigen processing and are encoded in close vicinity to the TAP genes. We investigated whether LMP2 and LMP7 are hyperexpressed in thyrocytes and islet cells in AITD and IDDM. Thyroid tissue from Graves' disease patients (GD, n = 8) and Hashimoto thyroiditis (HT, n = 1) and pancreatic tissue from IDDM patients (n = 4) as well as control tissues were examined by the two-color indirect immunofluorescence technique. The results demonstrate that, in normal glands, thyrocytes and pancreatic islet cells express comparable moderate to low levels of LMP2 and LMP7. In AITD and IDDM, expression of LMP2/7 in the endocrine cells was disparate: while in AITD glands there was hyperexpression of LMP2 and 7 parallel to that of HLA class I and TAP-1, in the islet cells of recent onset diabetic pancreases (n = 2) the level of LMP2 and 7 expression was totally normal, including islets that were infiltrated by lymphocytes and hyperexpressed HLA class I and TAP-1. These observations suggest different mechanisms of endogenous peptides generation at the target cells in AITD from IDDM. Since this is a key step for the maintenance of peripheral tolerance, it may help to understand some of the different clinical features of the two autoimmune diseases.

Prevention of onset in an insulin-dependent diabetes mellitus model, NOD mice, by oral feeding of Lactobacillus casei

The effect of Lactobacillus casei (LC) on the onset of diabetes in an insulin-dependent diabetes mellitus model, nonobese diabetic (NOD) mice, were examined. From the age of 4 weeks, female NOD mice were fed a diet of either standard laboratory chow (n = 12) or the same chow containing 0.05% weight heat-killed cells of LC (n = 12), and the onset of diabetes was thereafter recorded. The incidence of diabetes in the control group (10/12) was significantly higher than that in the LC-treated group (3/12) (p < 0.01). Pathological analysis in the LC-treated group revealed strong inhibition of the disappearance of insulin-secreting beta cells in Langerhans islets caused by autoimmune disease. The proportion of CD45R+ B-cells in the spleen was increased and that of CD8+ T-cells in spleen cells was decreased in the LC-treated group. Analysis of cytokine production revealed lower interferon-gamma production in the LC-treated group compared to the control group, while the interleukin (IL)-2 production was higher. The levels of IL-4, IL-5, IL-6 and IL-10 in the LC-treated group were somewhat higher than in the control group. Taken together, these findings clearly demonstrated that oral feeding of LC to NOD mice effectively inhibited the occurrence of diabetes and regulated the host immune response.

Bacterial cell wall products increase monocyte HLA-DR and ICAM-1 without affecting lymphocyte CD18 expression

Bacterial cell wall products such as lipopolysaccharide (LPS) and muramyl dipeptide (MDP) have the capacity to enhance immune responses to antigens. The expression of surface class II major histocompatibility antigens and the costimulatory receptors CD18 and CD54/ICAM-1 (intercellular adhesion molecule) was used to evaluate the comparative influence of these immunostimulators. On monocytes, both LPS and MDP increased the expression of human leukocyte antigen (HLA)-DR (maximal at 6 hr), CD18 (maximal at 1-3 hr), and ICAM-1 (maximal at 18-24 hr for LPS and 12 hr for MDP) without increasing the production of superoxide. MDP-induced ICAM-1 expression on monocytes returned to baseline values after 12 hr. On lymphocytes, only LPS increased ICAM-1 (after 18 hr) without affecting CD18, and a differential analysis demonstrated a generalized ICAM-1 upregulation in lymphocyte subsets after 18 hr: the most pronounced effect was measured in natural killer cells, followed by CD8(+) T cells, B cells, and CD4(+) T cells. MDP did not alter ICAM-1 or CD18 expression on lymphocytes. These similar but smaller effects of MDP may, in part, explain the lesser toxicity of MDP when compared to LPS.

Rheumatoid arthritis synovial fibroblast and U937 macrophage/monocyte cell line interaction in cartilage degradation

OBJECTIVE

To examine the interaction between synovial fibroblasts and macrophages in the context of cartilage degradation.

METHODS

An in vitro model of human cartilage degradation was used, in which purified populations of fibroblasts and macrophages were added to a radiolabeled cartilage disc. Cartilage destruction was measured by the percentage of radiolabel release.

RESULTS

Fibroblasts, obtained from either rheumatoid arthritis (RA) or osteoarthritis synovial tissue, could mediate cartilage degradation if cocultured with the U937 macrophage cell line. Skin and RA bone marrow fibroblasts had no degradative effect on cartilage. Fibroblast-macrophage contact was not required for cartilage degradation. Cartilage degradation by synovial fibroblasts was inhibited by antibodies to tumor necrosis factor alpha (TNF alpha), interleukin-1 beta (IL-1 beta), and IL-6. Cartilage degradation was almost completely abrogated by a combination of antibodies to TNF alpha and IL-1 beta. Contact between fibroblasts and cartilage was shown to be essential. Antibodies to CD44, but not to intercellular adhesion molecule 1, markedly inhibited cartilage degradation.

CONCLUSION

TNF alpha, IL-1 beta, and IL-6 were involved in the activation of synovial fibroblasts to cause cartilage degradation. Cartilage degradation occurred only when fibroblasts were in contact with cartilage. CD44 was demonstrated to be involved in the fibroblast-cartilage interaction.

Analysis of an interferon-gamma gene (IFNG) polymorphism in Danish and Finnish insulin-dependent diabetes mellitus (IDDM) patients and control subjects. Danish Study Group of Diabetes in Childhood

A CA-repeat polymorphism within the first intron of the interferon (IFN)-gamma gene was analyzed. This polymorphism was recently demonstrated to be associated with insulin-dependent diabetes mellitus (IDDM) in Japanese subjects. We typed 266 IDDM patients and 195 control subjects of Danish Caucasoid origin. No significant differences in allele or genotype frequencies between patients and control were observed. In addition, we typed 168 IDDM and 110 control subjects of Finnish origin. A significant disease association of the studied IFN-gamma allelic pattern was found (p = 0.029). Analysis of data according to HLA-DQB1 susceptibility status did not reveal heterogeneity of risk at the IFN-gamma locus in either of the populations. Fifty-five Danish and 94 Finnish IDDM multiplex families with at least two affected siblings (660 individuals) were typed to test for transmission disequilibrium (TDT). No evidence for overall transmission disequilibrium using either an allele-wise (p = 0.42; combined data) or a genotype-wise analysis (p = 0.21; combined data) could be detected. Thus, the modest significance level observed in the Finnish case-control study and the failure to replicate it by the TDT provide little support for the hypothesis that the IFN-gamma gene microsatellite is associated with IDDM.

Interaction of genetic and environmental factors in the pathogenesis of insulin-dependent diabetes mellitus

The current concept of the pathogenesis of insulin-dependent diabetes mellitus (IDDM) is based on the view that environmental factors, either alone or in combination, trigger in a genetically, susceptible individual an autoimmune process which leads to the destruction of the insulin-secreting beta cells. The identification of environmental risk factors for IDDM is of utmost importance with regard to possibilities for implementing preventive measures. Studies on the interaction between genetic and environmental factors may be complicated by the observations that genetic markers, e.g. HLA risk alleles, may vary from one population to another, and combinations of predisposing genes may differ between populations. In addition, the role of a given environmental trigger in initiating the autoimmune process may be variable in various individuals depending on the genetic set-up and other host-related characteristics. As prevention trials are already being initiated, and genetic screening is essential in the identification of individuals at increased risk of IDDM, it is crucial to learn more about the interaction of genetic and environmental factors in this disease.

Local expression of transgene encoded TNF alpha in islets prevents autoimmune diabetes in nonobese diabetic (NOD) mice by preventing the development of auto-reactive islet-specific T cells

Lately, TNF alpha has been the focus of studies of autoimmunity; its role in the progression of autoimmune diabetes is, however, still unclear. To analyze the effects of TNF alpha in insulin-dependent diabetes mellitus (IDDM), we have generated nonobese diabetic (NOD) transgenic mice expressing TNF alpha under the control of the rat insulin II promoter (RIP). In transgenic mice, TNF alpha expression on the islets resulted in massive insulitis, composed of CD4+ T cells, CD8+ T cells, and B cells. Despite infiltration of considerable number of lymphoid cells in islets, expression of TNF alpha protected NOD mice from IDDM. To determine the mechanism of TNF alpha action, splenic cells from control NOD and RIP-TNF alpha mice were adoptively transferred to NOD-SCID recipients. In contrast to the induction of diabetes by splenic cells from control NOD mice, splenic cells from RIP-TNF alpha transgenic mice did not induce diabetes in NOD-SCID recipients. Diabetes was induced however, in the RIP-TNF alpha transgenic mice when CD8+ diabetogenic cloned T cells or splenic cells from diabetic NOD mice were adoptively transferred to these mice. Furthermore, expression of TNF alpha in islets also downregulated splenic cell responses to autoantigens. These data establish a mechanism of TNF alpha action and provide evidence that local expression of TNF alpha protects NOD mice from autoimmune diabetes by preventing the development of autoreactive islet-specific T cells.

Tumor necrosis factor (TNF) microsatellite haplotypes in relation to extended haplotypes, susceptibility to diseases associated with the major histocompatibility complex and TNF secretion

TNFabc microsatellite haplotypes were determined on normal, type I diabetes and multiple sclerosis Caucasian MHC haplotypes in family studies. Although independent examples of conserved extended haplotypes usually had the same TNFabc haplotypes, there were a number of exceptions, suggesting that these loci are more mutable than most loci in the human MHC. Some TNFabc haplotypes were characteristic of only one extended haplotype, whereas others were shared by several different extended haplotypes. From the analysis of TNFabc on extended haplotype fragments, and assuming that the fragments arose by ancient homologous crossing over, it was possible to "map" TNF and how that it was somewhat closer to HLA-B than the complement region, corresponding to the physical map of this region. TNF haplotype associations with type I diabetes and multiple sclerosis were attributable to the known extended haplotype associations of these diseases. There was also a trend for higher TNF-alpha secretion by peripheral blood mononuclear cells from individuals homozygous for [HLA-B8, SC01, DR3] than from individuals homozygous for [HLA-B7, SC31, DR2].

Interferon-gamma in autoimmunity

Autoimmune disorders are characterized by abrogation of self-tolerance, resulting in emergence of activated self-reactive lymphocyte clones that trigger or maintain inflammatory reactions in specific organs. Interferon-gamma (IFN-gamma), as well as other cytokines, plays an important role as a regulator of the activation of self-reactive lymphocytes and of bystander and accessory cells that are involved in the autoimmune inflammatory response. In experimental models of autoimmunity, endogenous IFN-gamma has invariably been found to profoundly affect the disease course. However, it acts in one way in some diseases and in the opposite way in others.

Cytokines and production of surfactant components

The production of pulmonary surfactant, a complex of lipids and proteins that reduces surface tension at the alveolar air-liquid interface, is developmentally regulated. Several hormones, most notably glucocorticoids, are known to accelerate maturation of the surfactant system. Cytokines are polypeptides that act mostly in a paracrine fashion and possess a wide spectrum of activities on multiple types of cells. Many cytokines are produced by different lung cells a various stages of fetal development or under pathological conditions affecting the fetus. In addition, cytokines present in amniotic fluid or in the blood stream may reach the fetal lungs. Some cytokines, including epidermal growth factor, transforming growth factor-alpha, and interferon-gamma have been shown to stimulate the production of surfactant components. On the other hand, tumor necrosis factor and transforming growth factor-beta downregulate the production of surfactant lipids and proteins. We have recently shown that the proinflammatory cytokine interleukin-1 (IL-I) enhances the expression of surfactant protein A (SP-A) in fetal rabbit lung explants. In addition, injection of IL-I into the amniotic fluid of fetal rabbits enhances the expression of surfactant proteins and improves the lung compliance of preterm animals. Preterm delivery is often associated with subclinical intraamniotic infection. In these cases, amniotic fluid concentrations of IL-I are often elevated. We propose that this cytokine accelerates maturation of the surfactant system in fetal lungs and thus prepares the fetus for extrauterine life.

The pathology of the endocrine pancreas in type 1 (insulin-dependent) diabetes mellitus

Type 1 diabetes is an organ-specific autoimmune disease in which the insulin-secreting B cell is destroyed. Both genetic factors (linked to class II MHC genes) and environmental agents (viruses, diet) appear to be involved in the aetiology. Study of autopsy pancreases of children who die at presentation of their disease has proved elucidating. In such pancreases islets before, during and after B cell destruction, are all visible. The earliest defined immunological event in the disease process appears to be expression of interferon-alpha by insulin-containing B cells. Secretion of this cytokine is associated with hyperexpression of class I MHC by all the endocrine cells within insulin-containing islets. Another immunological phenomenon which is unique to type I diabetes is the presence of aberrant class II MHC molecule expression by B cells. This may induce autoimmunity by allowing antigen presentation of B cell specific antigens. If the onset of the disease process is marked by interferon-alpha expression by B cells then a search for the presence of a continuing viral infection in these cells may prove profitable, although no viruses have been found in them to date.

An association in non-insulin-dependent diabetes mellitus subjects between susceptibility to retinopathy and tumor necrosis factor polymorphism

In IDDM an association between diabetic retinopathy and polymorphic markers of MHC has been described. However, these associations are complicated by a primary association between the MHC and IDDM. Because the pathogenesis of retinopathy is likely to be the same in IDDM and NIDDM, NIDDM subjects with retinopathy would be the ideal population to study for an association with MHC markers. The following South Indian subjects were therefore studied: unselected NIDDM (n = 76), unselected IDDM (n = 99), non-diabetic controls (n = 96), NIDDM subjects with maculopathy (MAC), n = 55, NIDDM subjects with proliferative retinopathy (PR), n = 53, and without retinopathy (LTD), n = 46. DNA was amplified and studied using a microsatellite polymorphism located 3.5 kb upstream of TNF-beta within the MHC class III region on the short arm of chromosome 6. No differences in allelic distribution were observed between the random NIDDM subjects and controls (p = 0.17). Differences in allelic distribution were found between unselected IDDM and controls (P = 0.016) and between the NIDDM subjects with maculopathy and/or proliferative retinopathy and no retinopathy (P = 0.006). This association could be accounted for by those patients with proliferative retinopathy (MAC vs LTD, p = 0.23; MAC vs PR, p = 0.07; and PR vs LTD, p = 0.002).

The immunology of thyroid cancer

This article reviews the immunologic aspects of thyroid cancer, including thyroid-specific effector elements on thyroid cancer, and discusses the potential antigens, unique molecular markers, and transcription factors that could serve as targets for immunotherapy. The potential role of this type of treatment for thyroid cancer is examined also.

No primary association between the 308 polymorphism in the tumor necrosis factor alpha promoter region and insulin-dependent diabetes mellitus

Whereas TNF-alpha has been implicated in the pathogenesis of IDDM, its possible role as a primary genetic susceptibility factor has not been well investigated. In this study, we analyzed a biallelic polymorphism in the TNF-alpha promotor region in a large collection of IDDM patients and controls ascertained from two ethnic populations (U.S. Caucasians and Chinese in Taiwan). We report that the associations with TNF-alpha are due to linkage disequilibrium between TNF-alpha and the DR3-DQB1*0201 haplotype in both ethnic populations. Our analyses of extended haplotypes for the HLA region further substantiate the conclusion that no primary association exists between IDDM and the TNF-alpha promoter polymorphism.

Cytokine gene expression and autoantibody production in Sjögren's syndrome of MRL/lpr mice

In an attempt to elucidate the mechanism of development of organ-specific autoimmune lesions resembling human Sjögren's syndrome of MRL/lpr mice, we have analyzed local cytokine gene expressions and organ-specific autoantibody production in vivo. We have demonstrated that a major proportion of T cells bearing CD4 and V(beta)8 molecules are essentially responsible for triggering the autoimmunity in the salivary glands of MRL/lpr mice. The local cytokine gene expressions including interferon(IFN)-gamma, IL-12(p40) mRNAs were observed during the course of murine Sjogren's syndrome in MRL/lpr autoimmune strain. In particular, a high level of local expressions of IL-12 mRNA was detected earlier in the proinflammatory stage of autoimmune lesions. A significant level of local expression of MHC class-II(I-Ak) mRNA was detected before the onset of inflammatory lesions in the salivary glands, and I-Ak-positive epithelial duct cells were frequently observed in the salivary glands of MRL/lpr mice. In addition, we found the salivary gland-specific autoantibody in sera from MRL/lpr mice with early phase of autoimmune lesions by immunoblot analysis. These results suggest that cytokine gene stimulation and autoantibody production are essentially involved in the development of organ-specific autoimmune lesions in Sjögren's syndrome of MRL/lpr mice.

Elevated serum levels of macrophage-derived cytokines precede and accompany the onset of IDDM

To determine whether cytokines could have a role in the development of insulin-dependent diabetes mellitus (IDDM), we measured serum levels of cytokines derived from T helper 1 (interleukin-2 and interferon-gamma), T helper 2 (interleukin-4 and interleukin-10) lymphocytes and macrophages (tumour necrosis factor-alpha, interleukin-1 alpha and interleukin-1 beta) in patients before and after the onset of IDDM. Recently diagnosed IDDM patients had significantly higher levels of interleukin-2, interferon-gamma, tumour necrosis factor-alpha and interleukin-1 alpha than patients with either long-standing IDDM, non-insulin-dependent diabetes (NIDDM), Graves' disease, or control subjects (p < 0.05 for all). Compared with control subjects, patients with long-standing IDDM and those with NIDDM had higher interleukin-2 and tumour necrosis factor-alpha levels (p < 0.01 for all). Interleukin-4 and interleukin-10 were detectable in sera of patients with Graves' disease only, while interleukin-1 beta was not detectable in the serum of any control or test subject. To investigate whether high cytokine levels precede the onset of IDDM, we studied 28 non-diabetic identical co-twins of patients with IDDM, followed-up prospectively for up to 6 years after the diagnosis of the index. Levels of tumour necrosis factor-alpha and interleukin-1 alpha were elevated above the normal range more frequently in the eight twins who developed diabetes than in those 20 who did not (p < 0.005). Analysis of T helper 1 and T helper 2 profiles of the twin groups did not reveal a clear difference between prediabetic twins and twins remaining non-diabetic. These results support the notion that T helper 1 lymphocytes may play a role in the development of IDDM. This is associated with release of macrophage-derived cytokines, which is also a feature of the prediabetic period. The lack of evidence of a dominant T helper 1 profile of cytokine release before diabetes onset suggests that additional events, activating this arm of the cellular immune response, are required in the immediate prediabetic period.

The contribution of insulitis to diabetes development in tumor necrosis factor transgenic mice

The inflammatory response mediated by cytokines such as TNF can promote recruitment of lymphocytes to a tissue. Moreover, if other conditions are met, this can provide a predisposing role to autoimmune disease. TNFs induce the appearance of adhesion molecules (and presumably, therefore, extravasation of lymphocytes into tissue from the vasculature) and increase the levels of MHC class I on tissue. However, it is not clear which of these effects plays the key role in induction of disease. This should be the subject of further study. The data substantiate the hypothesis that chronic inflammation might play a precipitating role in autoimmunity and could be one of the environmental factors of importance in the development of so many autoimmune diseases.

TNF-alpha inhibits glucose-induced insulin secretion in a pancreatic beta-cell line (INS-1)

Recent studies suggest that TNF-alpha affects various biochemical and physiological processes which may be linked to the etiology of non-insulin-dependent diabetes mellitus (NIDDM). For example, TNF-alpha interferes with the signaling of the insulin receptor and the metabolism of glucose transporters. The possibility that TNF-alpha might directly reduce glucose-stimulated insulin secretion in pancreatic beta-cells was examined by using an established pancreatic beta-cell line (INS-1). TNF-alpha did not affect glucose-induced acute insulin secretion (30 min). However, over a longer time period (24 h), TNF-alpha decreased glucose-induced insulin secretion without affecting the total amount of insulin in the cell. In the presence of TNF-alpha levels of 0, 10, 100 and 1000 U/ml, the respective 20 mM glucose-induced insulin secretion was 1.736 +/- 0.166, 1.750 +/- 0.302, 1.550 +/- 0.200, and 1.400 +/- 0.112 mU/ml per 3 x 10(5) cells in 24 h.

Genetic polymorphism of the human tumor necrosis factor region in insulin-dependent diabetes mellitus. Linkage disequilibrium of TNFab microsatellite alleles with HLA haplotypes

The TNF region within the MHC includes a number of immunologically important genes. Microsatellites TNFa and TNFb adjacent to TNF exhibit extensive polymorphism. Employing a PCR-based technique, we identified TNFab haplotypes and defined their distribution in 97 controls and 48 diabetics of Caucasoid origin in a search for other genes within the MHC potentially associated with IDDM. Twenty-five different TNFab haplotypes were identified. A significant difference (p < 0.0005) in frequency between patients and controls was found for TNFa1b5 (relative risk 53). However, no other TNFab microsatellites demonstrated significantly different frequencies. Among diabetics TNFa1b5 was found to be in linkage disequilibrium with HLA-DR3-B18, a haplotype known to be associated with IDDM. Thus the increased frequency of TNFa1b5 among diabetics could reflect a linkage disequilibrium with a gene within the TNF region or with other genes, including the HLAs, which characterize this haplotype. In both controls and diabetics TNFa2b3 and TNFa7b4 were in linkage disequilibrium with DR3-B8 and DR7, respectively. Among diabetics, TNFa2b1 and TNFa6b5 were in linkage disequilibrium with DR4-B62 and DR4-B44, respectively. It is intriguing that TNFab haplotypes, represented by a short piece of about 200 nucleotides in the untranslated region upstream of TNF beta gene, maintain strong linkage disequilibria with different HLA haplotypes extending over 1 million base pairs. The identification of TNFab microsatellites exhibiting a high polymorphic index in a region lacking known polymorphic markers may provide potentially important information regarding the association of HLA haplotypes with autoimmune diseases, as they are in close proximity to other genes of immunologic importance.

Major histocompatibility class II peptide occupancy, antigen presentation, and CD4+ T cell function in mice lacking the p41 isoform of invariant chain

We used a "hit and run" gene targeting strategy to generate mice expressing only the p31 isoform of the conserved invariant (Ii) chain associated with major histocompatibility complex (MHC) class II molecules. Spleen cells from these mice appear indistinguishable from wild type with respect to class II subunit assembly, transport, peptide acquisition, surface expression, and the ability to present intact protein antigens. Moreover, these mutant mice have normal numbers of thymic and peripheral CD4+ T cells, and intact CD4+ T-dependent proliferative responses towards a soluble antigen. In short, MHC class II expression and function are surprisingly unaffected in mice lacking p41 invariant chain, implying that the p31 and p41 isoforms may be functionally redundant in the intact animal.

Functional roles of the transcription factor Oct-2A and the high mobility group protein I/Y in HLA-DRA gene expression

The class II major histocompatibility complex gene HLA-DRA is expressed in B cells, activated T lymphocytes, and in antigen-presenting cells. In addition, HLA-DRA gene expression is inducible in a variety of cell types by interferon-gamma (IFN-gamma). Here we show that the lymphoid-specific transcription factor Oct-2A plays a critical role in HLA-DRA gene expression in class II-positive B cell lines, and that the high mobility group protein (HMG) I/Y binds to multiple sites within the DRA promoter, including the Oct-2A binding site. Coexpression of HMG I/Y and Oct-2 in cell lines lacking Oct-2 results in high levels of HLA-DRA gene expression, and in vitro DNA-binding studies reveal that HMG I/Y stimulates Oct-2A binding to the HLA-DRA promoter. Thus, Oct-2A and HMG I/Y may synergize to activate HLA-DRA expression in B cells. By contrast, Oct-2A is not involved in the IFN-gamma induction of the HLA-DRA gene in HeLa cells, but antisense HMG I/Y dramatically decreases the level of induction. We conclude that distinct sets of transcription factors are involved in the two modes of HLA-DRA expression, and that HMG I/Y may be important for B cell-specific expression, and is essential for IFN-gamma induction.