The proapoptotic BH3-only proteins Bim and Puma are downstream of endoplasmic reticulum and mitochondrial oxidative stress in pancreatic islets in response to glucotoxicity.

Apoptosis of pancreatic beta cells is a feature of type 2 diabetes and its prevention may have therapeutic benefit. High glucose concentrations induce apoptosis of islet cells, and this requires the proapoptotic Bcl-2 homology domain 3 (BH3)-only proteins Bim and Puma. We studied the stress pathways induced by glucotoxicity in beta cells that result in apoptosis. High concentrations of glucose or ribose increased expression of the transcription factor CHOP (C/EBP homologous protein) but not endoplasmic reticulum (ER) chaperones, indicating activation of proapoptotic ER stress signaling. Inhibition of ER stress prevented ribose-induced upregulation of Chop and Puma mRNA, and partially protected islets from glucotoxicity. Loss of Bim or Puma partially protected islets from the canonical ER stressor thapsigargin. The antioxidant N-acetyl-cysteine also partially protected islets from glucotoxicity. Islets deficient in both Bim and Puma, but not Bim or Puma alone, were significantly protected from killing induced by the mitochondrial reactive oxygen species donor rotenone. Our data demonstrate that high concentrations of glucose induce ER and oxidative stress, which causes cell death mediated by Bim and Puma. We observed significantly higher Bim and Puma mRNA in islets of human donors with type 2 diabetes. This indicates that inhibition of Bim and Puma, or their inducers, may prevent beta-cell destruction in type 2 diabetes.

The development of atopic dermatitis is independent of Immunoglobulin E up-regulation in the K14-IL-4 SKH1 transgenic mouse model.

BACKGROUND: We have successfully generated an IgE-associated (extrinsic/allergic) mouse model of atopic dermatitis in K14-IL-4-Tg/CByB6 mice. The newly described subset of non-IgE-associated (intrinsic/non-allergic) atopic dermatitis in human patients raises the question on the role of IgE in the pathogenesis. OBJECTIVE: The aim of this study was to develop a non-IgE-associated atopic dermatitis model in K14-IL-4-Tg/SKH1 mice. METHODS: K14-IL-4-Tg/CByB6 mice were crossed with SKH1 mice to produce K14-IL-4-Tg/SKH1 mice. Phenotypes of clinical and histological, cytokine expression in the skin lesions, and total serum IgE in K14-IL-4-Tg/CByB6 and K14-IL-4-Tg/SKH1 mice were compared. The CD40 and CD40L on T and B cells were also studied to differentiate their roles in IgE production. RESULTS: K14-IL-4-Tg/SKH1mice had a normal total serum IgE level and manifested a chronic inflammatory skin phenotype identical to that of K14-IL-4-Tg/CByB6 IgE-mediated mice in clinical morphology, histology, infiltration of mononuclear cells/eosinophils/mast cells, mast cell degranulation, and up-regulation of chronic lesional cytokine mRNA expression of IL-1 beta, IL-3, IL-4, IL-6, IL-10, IL-12, IL-13, IFN-gamma, TNF-alpha, and TNF-beta. We also found that the inability of CD4(+) T cells of the K14-IL-4-Tg/SKH1mice to up-regulate CD40L expression upon stimulation might account for their inability to up-regulate the IgE level. B cell abnormality was ruled out as CD19(+) B cells of K14-IL-4-Tg/SKH1 mice synthesized the same amount of IgE in vitro compared with K14-IL-4-Tg/CByB6 mice in the presence of IL-4 and soluble CD40L. Our studies further suggested that the defect of early growth response-1 in T cells might be responsible for the impaired CD40L up-regulation in K14-IL-4-Tg/SKH1 mice. CONCLUSION: K14-IL-4-Tg/SKH1 mice developed skin inflammation that resembled human intrinsic atopic dermatitis. Therefore, this model may be suitable to study the pathogenesis of intrinsic atopic dermatitis.

Involvement of 4-1BB (CD137)-4-1BBligand interaction in the modulation of CD4 T cell-mediated inflammatory colitis.

4-1BB ligand (4-1BBL) expressed on antigen-presenting cells interacts with 4-1BB on activated T cells (especially CD8+ cells) and co-stimulates the latter to secrete cytokines and to proliferate. The role of 4-1BB-4-1BBL interaction was studied here in a model of colitis based on naive CD4+ T cell transfer to SCID mice, a disease model in which CD8 cells do not take part. We found that CD4+ T cells from 4-1BB-deficient mice, after transfer in SCID mice, proliferated more rapidly compared to wild-type CD4+ T cells. Mice reconstituted with naive CD4+ T cells from 4-1BB-deficient mice developed colitis, however, with a mixed Th1/Th2 response, in contrast to the Th1-type response in mice reconstituted with wild-type naive CD4+ T cells. Importantly, this altered cytokine response did not temper colitis severity. Although it has been reported previously that 4-1BB co-stimulation may contribute to regulatory T cell functioning, we found that CD4+CD25+ regulatory T cells from 4-1BB-deficient mice were perfectly able to prevent naive CD4+ T cell-induced colitis. In conclusion, our data provide evidence that 4-1BB-4-1BBL interaction modulates the effector CD4+ T cell-driven immune response and cytokine production in experimental colitis without affecting regulatory T cell function.

1Alpha,25-dihydroxyvitamin D3 restores thymocyte apoptosis sensitivity in non-obese diabetic (NOD) mice through dendritic cells.

AIMS/HYPOTHESIS: Resistance of NOD thymocytes to apoptosis-inducing signals is restored by 1alpha,25-dihydroxyvitamin D3 (1alpha,25OH2D3), a therapy preventing diabetes in NOD mice. We studied whether modulation of thymocyte apoptosis is due to direct effects on thymic T lymphocytes or indirect effects via thymic dendritic cells, since both cell types constitute known targets for 1alpha,25OH2D3. METHODS AND RESULTS: Female NOD mice were treated with 1alpha,25OH2D3 (5microg/kg/2d) from 21 to 70 days. Vehicle-treated NOD and NOR mice served as controls. Analysis of thymic T lymphocytes from 1alpha,25OH2D3)-treated mice revealed a decrease in number of apoptosis-resistant CD4+CD8+ and CD4+CD8-HSA(high) T lymphocyte subsets, higher pro-apoptotic IL-2 and FasL, and lower anti-apoptotic Bclx-L mRNA expression levels. Thymic dendritic cells from 1alpha,25OH2D3-treated NOD mice had increased CD8alpha+FasL+ and CD80+/86+ expression compared to control NOD mice. In a syngeneic co-culture system of thymocytes and thymic dendritic cells, apoptosis levels were 20% higher only in co-cultures where both T cell- and dendritic cell-compartments originated from 1alpha,25OH2D3-treated mice. Activation-induced cell death-sensitivity in peripheral T lymphocytes was comparable to levels present in NOR mice, confirming better thymic selection in 1alpha,25OH2D3-treated mice. CONCLUSION/INTERPRETATION: We conclude that 1alpha,25OH2D3 needs both thymic T cell- and dendritic cell-compartments to exert its apoptosis-restorative effects in NOD thymocytes.

Early up-regulation of Th2 cytokines and late surge of Th1 cytokines in an atopic dermatitis model.

We investigated cytokine profiles in interleukin (IL)-4 transgenic (Tg) mice with a skin inflammatory disease resembling human atopic dermatitis. cDNA microarray revealed that the mRNAs encoding IL-1beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-13, tumour necrosis factor (TNF)-alpha, TNF-beta and interferon (IFN)-gamma were up-regulated in the skin of late lesion Tg mice and to a lesser degree in non-lesion Tg mice when compared to those of non-Tg mice. Real time reverse transcription-polymerase chain reaction (RT-PCR) analyses indicated that the cDNA copy numbers of IL-1beta, IL-4, IL-6, IL-10, TNF-alpha and IFN-gamma from the skin of late, early and non-lesions increased significantly compared to non-Tg mice. IL-2 and IL-12p40 cDNA copy numbers were increased significantly in early, but not late, lesions. Interestingly, IL-1beta, IL-3, IL-4, IL-5, IL-6, IL-10, IL-13, TNF-alpha, and IFN-gamma cDNAs were increased significantly the skin of before-onset and/or non-lesion mice. Flow cytometry analyses demonstrated an increased percentage of keratinocytes producing IL-4 as the disease progressed. The percentage of IL-2, IL-4, IL-10 and IFN-gamma-producing T cells and IL-12-producing antigen-presenting cells in skin-draining lymph nodes and inflammatory skin also increased, particularly in mice with late lesion. These results suggest that disease induction is primarily triggered by Th2 cytokines and that Th1, Th2 and non-Th proinflammatory cytokines are all involved in the disease process.

NOD macrophages produce high levels of inflammatory cytokines upon encounter of apoptotic or necrotic cells.

During the development of type 1 diabetes, pancreatic beta-cells are subject to an immune attack, leading to their apoptotic or necrotic cell death. Apoptotic beta-cells are also present during periods of tissue remodeling, such as in early life. Macrophages should clear apoptotic cells silently without production of pro-inflammatory cytokines. The aim of the present study was to investigate the cytokine pattern of NOD macrophages exposed to apoptotic or necrotic cells in vitro. In contrast to the limited response of macrophages from C57BL/6 or NOR mice, NOD macrophages reacted aberrantly to both necrotic and apoptotic cells, with secretion of inappropriately high amounts of IL1beta and TNFalpha. Further exploration of the macrophage behavior showed an excessive response of NOD macrophages when exposed to LPS (high iNOS and IL12p40 levels), accompanied by hyper-activation of NF-kappaB(p65). In contrast, NOD macrophages failed to up-regulate IL1beta and IL12p40 in response to IFNgamma. This failure correlated with low protein levels and a low phosphorylation state of STAT1alpha. We conclude that NOD macrophages have severely aberrant cytokine expression patterns that could contribute to the initiation or continuation of an immune attack towards the pancreatic beta-cells and thus onset and progression of type 1 diabetes.

The use of real-time reverse transcriptase PCR for the quantification of cytokine gene expression.

Real-time reverse transcriptase polymerase chain reaction (RT-PCR) is becoming a widely used method to quantify cytokines from cells, tissues, or tissue biopsies. The method allows for the direct detection of PCR product during the exponential phase of the reaction, combining amplification and detection in a single step. Using TaqMan chemistry (Applied Biosystems, Foster City, CA) and the ABI Prism 7700 Sequence Detection System (Applied Biosystems), we validated a large panel of murine and human cytokines, as we as other factors playing a role in the immune system, such a chemokines and apoptotic markers. Although the method allows fast, sensitive, and accurate quantification, different control assays are necessary for the method to be reliable. By construction of complementary DNA (cDNA) plasmid clones, standard curves are generated that allow direct quantification of every unknown sample. Furthermore, the choice of a reliable housekeeping gene is very important. Finally, co-amplification of contaminating genomic DNA is avoided by designing sets of primers located in different exons or or intron-exon junctions. In conclusion, the real-time RT-PCF technique is very accurate and sensitive, allows high through put, and can be performed on very small samples. The development of real-time RT-PCR has resulted in an exponential increase in its use over the last couple of years, and the method has undoubtedly become the standard for quantifying cytokine patterns, clarifying many functional properties of immune cells and their associated diseases.

A murine interleukin-4-Ig fusion protein regulates the expression of Th1- and Th2-specific cytokines in the pancreas of NOD mice.

Interleukin (IL)-4 is a key cytokine in T-helper type 2 (Th2) immune response. We have constructed a dimeric IL-4 molecule consisting of the murine IL-4 and the murine Fc part of IgG2a. We first tested the biological activity of the chimeric protein by in vitro studies using isolated murine spleen cells. IL-4-Ig was found to downregulate LPS-induced IFN-gamma and TNF-alpha production. The immunomodulatory potential of the fusion protein was also analyzed in non-obese diabetic (NOD) mice, an animal model for human type 1 diabetes. Female NOD mice aged 10 weeks were treated once with cyclophosphamide to accelerate and synchronize the progression of insulitis. Treatment with IL-4-Ig induced strong modulation of the pancreatic cytokine balance. Expression was downregulated for both Th1-specific cytokine IFN-gamma and the Th2-specific cytokine IL-10. IL-12p40 expression was only slightly affected. Interestingly, infiltration increased in the islets of IL-4-Ig-treated animals, and therefore did not correlate with the decreased IFN-gamma expression. Hence, IL-4-Ig did not prevent the progression from peri- to intra-insulitis, but suppressed inflammatory cytokine production. In most experiments, the biological activity of IL-4-Ig and IL-4 was comparable. We conclude that treatment with the chimeric protein IL-4-Ig effectively downregulates Th1 responses but simultaneously augments intra-islet infiltration.

Transforming growth factor-beta inhibits lymphokine activated killer cytotoxicity of bone marrow cells: implications for the graft-versus-leukemia effect in irradiation allogeneic bone marrow chimeras.

BACKGROUND: We have previously shown that allogeneic bone marrow (BM) chimeras preconditioned with total lymphoid irradiation and low-dose total body irradiation (TLI/TBI) develop a stronger graft-versus-leukemia (GVL) effect than chimeras preconditioned with high-dose total body irradiation only (TBI). Here, we report on the possible role of cytokines in the mechanism underlying this GVL effect. METHODS: Splenic mRNA levels of the cytokines interleukin (IL)-1, IL-2, IL-4, IL-6, IL-7, IL-10, IL-12, IL-15, interferon-gamma, tumor necrosis factor-alpha, and transforming growth factor-beta (TGF-beta), and of inducible nitric oxide synthetase were determined by reverse transcription-polymerase chain reaction in TLI/TBI- or TBI-conditioned C3H/AKR BM chimeras challenged with AKR-type BW5147.3 leukemia cells. Ex vivo TGF-beta protein production by splenocytes was determined using ELISA. The possibility that cytokines influence the GVL effect by modulating the activity of IL-2-activated lymphocytes (LAK cells) was investigated by in vitro assays on donor-type BM cells. RESULTS: Of all cytokine mRNA levels studied, those of TGF-beta and IL-7 were different between groups; both were significantly more elevated in TBI- than in TLI/ TBI-conditioned or normal mice. Differences were apparent after conditioning and were not influenced by additionally injected BM or leukemia cells. Cultured splenocytes of TBI-conditioned animals produced significantly more TGF-beta protein than those of TLI/TBI-conditioned ones or normal controls. r-TGF-beta but not r-IL-7 suppressed in vitro LAK activity of donor-type BM cells against BW5147.3 cells in a dose-dependent way. CONCLUSIONS: High-dose TBI-induced, host-derived splenic TGF-beta may inhibit generation of LAK cells from subsequently transplanted donor BM cells, suppressing their capacity to generate cytotoxicity upon injection of leukemia cells. The cytokine profile, induced by irradiation in host hematopoietic organs, can significantly modify posttransplant immunological processes such as the GVL effect and graft-versus-host disease (GVHD).

Streptococcal wall component OK432 restores sensitivity of non-obese diabetic (NOD) thymocytes to apoptotic signals.

AIMS/HYPOTHESIS: The streptococcal wall component, OK432, prevents diabetes in NOD mice and BB rats by elimination of effector cells. Based on the knowledge of a link between autoimmunity and resistance of immune cells to elimination by apoptosis, we investigated whether OK432 treatment restored the sensitivity of NOD lymphocytes to apoptotic signals centrally (thymus) or peripherally (spleen) or both and we examined the pathways for the enhanced apoptosis rate. METHODS: We treated NOD mice with OK432 (0.1 mg/kg i.p. weekly from 21 to 70 days). Apoptosis was measured by TUNEL 16 h after cyclophosphamide (70 mg/kg) and 24 h after dexamethasone (0.2 mg/mouse). Real time quantitative RT-PCR was used to investigate changes in gene expression. RESULTS: Thymocyte apoptosis levels after cyclophosphamide were restored by OK432 treatment to levels observed in C57BL/6 mice: in NOD males apoptosis increased from 8 +/- 1% to 18 +/- 5% (p < 0.05) compared with 20 +/- 4% in C57BL/6 males, and in NOD females from 6+/- 2% to 11 +/- 2% (p < 0.05) compared with 12 +/- 2% in C57BL/6 females. The dexamethasone-induced thymocyte apoptosis rate was equally restored by OK432 treatment (58 +/- 4% vs 41 +/- 3% in control males (p < 0.0005) and 39 +/- 5% vs 26 +/- 3% in control females (p < 0.05)]. No change in apoptosis levels was on the contrary observed in splenocytes after OK432 treatment. By RT-PCR analysis of a panel of apoptosis-related genes in thymocytes we showed a down-regulation of anti-apoptotic Bcl-xL and c-myc by OK432 treatment. CONCLUSIONS/INTERPRETATION: Our data suggest that OK432 prevents diabetes in NOD mice by better elimination of effector cells through increased sensitivity to apoptotic signals centrally in the thymus.

Prevention of experimental colitis in SCID mice reconstituted with CD45RBhigh CD4+ T cells by blocking the CD40-CD154 interactions.

Increased expression of CD40 and CD40 ligand (CD40L or CD154) has been found in inflamed mucosa of human inflammatory bowel disease (IBD), and interactions between these molecules seem to be involved in local cytokine production by macrophages. However, the precise role of CD40 signaling in the pathogenesis of IBD is still poorly understood. The aim of the present study was to investigate the in vivo relevance of CD40 signaling in experimental colitis in SCID mice reconstituted with syngeneic CD45RBhighCD4+ T cells. The results demonstrated that CD40+ and CD40L+ cells as well as their mRNA levels were significantly increased in inflamed mucosa. Administration of anti-CD40L neutralizing mAb over an 8-wk period starting immediately after CD45RBhighCD4+ T cell reconstitution completely prevented symptoms of wasting disease. Intestinal mucosal inflammation was effectively prevented, as revealed by abrogated leukocyte infiltration and decreased CD54 expression and strongly diminished mRNA levels of the proinflammatory cytokines IFN-gamma, TNF, and IL-12. When colitic SCID mice were treated with anti-CD40L starting at 5 wk after T cell transfer up to 8 wk, this delayed treatment still led to significant clinical and histological improvement and down-regulated proinflammatory cytokine secretion. These data suggest that the CD40-CD40L interactions are essential for the Th1 inflammatory responses in the bowel in this experimental model of colitis. Blockade of CD40 signaling may be beneficial to human IBD.

Identification and immune regulation of 25-hydroxyvitamin D-1-alpha-hydroxylase in murine macrophages.

Receptors for 1,25(OH)2vitaminD3 are found in most immune cells and important immunological effects have been described in vitro, reflected by its capacity to prevent autoimmunity and to prolong graft survival. The aim of this study was to examine the presence and nature of the enzyme responsible for final activation of the molecule, 1-alpha-hydroxylase, in murine macrophages and to analyse its regulation and possible role in the immune system. Peritoneal macrophages from C57Bl/6 mice were incubated with lipopolysaccharide (LPS; 100 microg/ml), interferon-gamma (IFN-gamma; 500 U/ml) or a combination of both. By quantitative reverse transcriptase-polymerase chain reaction, using primers based on the murine renal cDNA sequence, low levels of 1-alpha-hydroxylase mRNA were detected in freshly isolated cells (18 +/- 7 x 10-6 copies/beta-actin copies). Analysis of the cDNA sequence of the gene revealed identical coding sequences for the macrophage and renal enzymes. mRNA levels rose three-fold with LPS (NS), but a six-fold increase was seen after IFN-gamma stimulation (P < 0.05). Combining LPS and IFN-gamma did not result in a major additional increase, but addition of cyclosporin A further increased levels 2.5-fold both in IFN-gamma- and combination-stimulated cells (P < 0.05). Time course analysis revealed that up-regulation of 1-alpha-hydroxylase was a late phenomenon, preceded by the up-regulation of activating macrophage products such as IL-1 and tumour necrosis factor-alpha. Finally, a defect in 1-alpha-hydroxylase up-regulation by immune stimuli was found in autoimmune non-obese diabetic mice. In conclusion, we propose that the up-regulation of 1-alpha-hydroxylase in activated macrophages, resulting in the synthesis of 1,25(OH)2D3, might be a negative feedback loop in inflammation. A defect in this system might be an additional element in tipping the balance towards autoimmunity.

Influence of the additional injection of host-type bone marrow on the immune tolerance of minor antigen-mismatched chimeras: possible involvement of double-negative (natural killer) T cells.

BACKGROUND: It has previously been demonstrated that adding T cell-depleted (TCD) host bone marrow (BM) to an MHC-mismatched BM inoculum allows for induction of long-term stable chimeras without graft-versus-host disease (GVHD) even when non-TCD allogeneic BM was used. AIMS: The present study was undertaken to investigate immune tolerance mechanisms in minor antigen-mismatched allogeneic BM chimeras when host-type BM was added to the BM inoculum. METHODS: C3H (H2k, Thy 1.2, Mls 2a) recipients were conditioned with 9.5 gray (Gy) of total body irradiation. To exclude any interference with possible subclinical GVHD, 5x10(6) TCD AKR (H2k, Thy 1.1, Mls 1a) BM cells were injected with (syn + allo) or without (allo) 5x 10(6) TCD C3H BM cells. Chimerism, clonal deletion, and T lymphocyte subsets were scored using FACS and anti-mouse Thy, Vbeta6, Vbeta3, CD3, CD4, or CD8 monoclonal antibodies. The stability of tolerance was studied by investigating mixed lymphocyte reaction and cytotoxic T cell induction in chimeras after immunization with host, donor, or third-party (BALB/c) splenocytes. Breaking of chimerism was attempted by injecting nontolerant 40x10(6) host-type splenocytes 2 months after BM transplantation. Cytokines and Valpha14 mRNA were assayed using real time quantitative reverse transcriptase-polymerase chain reaction at 4 and 48 hr, respectively, after injection of nontolerant host-type splenocytes. RESULTS: Both groups of mice became long-term stable mixed chimeras without any clinical sign of GVHD. Neither group was able to produce antihost nor antidonor cytotoxic T cells, even after immunization. The addition of syngeneic BM to the allogeneic inoculum reduced the overall level of allogeneic chimerism (from approximately 70% or approximately 85% in peripheral blood lymphocytes and spleen, respectively, in allo chimeras versus approximately 35% and approximately 60% in syn + allo chimeras). Moreover, it resulted in complete clonal deletion of both host-reactive (Vbeta3) and donor-reactive (Vbeta6) lymphocytes in syn + allo chimeras in contrast to in allo chimeras, in which only donor-reactive lymphocytes were completely deleted. After nontolerant C3H splenocyte injection, high levels of interleukin 2 mRNA were produced and chimerism decreased in syn + allo chimeras. In contrast, in allo chimeras, this maneuver was followed by the production of higher levels of interleukin 4 and interferon-gamma, and of Valpha14 mRNA, as well as by the proliferation of CD3+CD4-CD8- (double-negative) T cells and by an increase of donor chimerism. CONCLUSION: The addition of host-type BM to the allogeneic inoculum has an influence on the level of chimerism, the extent of clonal deletion, and the reaction of chimeras after the injection of nontolerant host-type splenocytes. In the latter phenomenon, cytokine production and proliferation of Valpha14+ CD3+CD4-CD8- (double-negative, natural killer T) lymphocytes may be involved.

Effect of staphylococcal enterotoxin B injection on the development of experimental autoimmune encephalomyelitis: influence of cytokine and inducible nitric oxide synthase production.

Possible mechanisms involved in the protective effect of staphylococcal enterotoxin B (SEB) injection on the subsequent development of experimental autoimmune encephalomyelitis (EAE) were investigated. Only partial clonal deletion and anergy of Vbeta8 + T-lymphocytes were documented after myelin basic protein immunization in SEB injected mice. Brain permeability was not influenced. Within the brain or during in vitro rechallenge assays SEB protected mice produced significantly more IL-10, IL-4, TNF-alpha and iNOS. It is suggested that the immune deviating effect of SEB may be involved in its EAE protective effect.

alpha2-macroglobulin- and murinoglobulin-1- deficient mice. A mouse model for acute pancreatitis.

Mice deficient in either or both mouse alpha2-macroglobulin (MAM) and murinoglobulin-1 (MUG1) were generated and proved phenotypically normal under standard conditions. Acute pancreatitis was induced with a diet deficient in choline and methionine, supplemented with ethionine. The mortality was less than 25% in wild-type mice, as opposed to at least 56% in knockout mice, and was highest (70%) in MAM-/- mice, with earliest onset at 2 days. Plasma amylase and lipase levels were increased, but pancreatic tissue appeared histologically variable in individual mice. The clinical symptoms were most severe in MAM-/- mice and, surprisingly, were not aggravated in the double knockout mice, suggesting that the lack of proteinase inhibition capacity was not the major problem. Therefore, we analyzed the expression of 21 different cytokines and polypeptide factors in the pancreas of all experimental groups of mice. Interleukin-1-receptor antagonist mRNA was consistently induced by the diet in the pancreas of MAM-/- mice, and transforming growth factor-beta, tumor necrosis factor-alpha, tumor necrosis factor-beta, beta-lymphotoxin, and interferon-gamma mRNA levels were also increased. The data demonstrate the important role of alpha2-macroglobulin (A2M) in acute pancreatitis as both a proteinase inhibitor and a cytokine carrier. Mice deficient in MAM and/or MUG thus offer new experimental models for defining in vivo the role of the macroglobulins in pancreatitis and in other normal and pathological processes.

Prevention of type I diabetes in nonobese diabetic mice by late intervention with nonhypercalcemic analogs of 1,25-dihydroxyvitamin D3 in combination with a short induction course of cyclosporin A.

In nonobese diabetic (NOD) mice, type I diabetes can be prevented without generalized immunosuppression by nonhypercalcemic analogs of vitamin D3 when treatment is started early, i.e. before the autoimmune attack, reflected by insulitis, occurs. The aim of this study was to investigate whether these substances can arrest progression to clinically overt diabetes when administered in a more advanced disease stage, namely when the autoimmune attack is ongoing, reflecting the situation in prediabetic subjects in whom immune intervention is being considered. We, therefore, evaluated the protective potential of MC1288 (20-epi-1,25-dihydroxyvitamin D3) a nonhypercalcemic analog of 1,25-dihydroxyvitamin D3, both alone and in combination with a short induction course of cyclosporin A, in NOD mice that already have insulitis, as demonstrated in pancreatic biopsies performed 15 days before the start oftherapy. Subsequently, mice were randomized into a control group, receiving the treatment vehicle (n = 26), and three treatment groups, receiving, respectively, 7.5 mg/kg x day cyclosporin A (CyA) from days 85-105 (n = 19), 0.1 microg/kg x 2 days MC1288 from days 85-200 (n = 20), or the combination of these two regimens (n = 20). At the time of the pancreatic biopsy (day 70), insulitis was evenly distributed in all groups, and 27.7% of the islets scored showed signs of destructive insulitis. Diabetes outcome by 200 days was 74% (14 of 19) in the CyA-treated group, comparable to the diabetes incidence in control mice (65%; 17 of 26; P = NS). Treatment with MC1288 alone could not reduce disease incidence (70%; 14 of 20), but the combination therapy reduced diabetes incidence to 35% (7 of 20; P < 0.05 vs. untreated; P < 0.01 vs. CyA group; P < 0.025 vs. MC1288). All treatments were well tolerated, without major side-effects on calcium or bone metabolism and without signs of generalized immunosuppression. Cotransfer experiments could not reveal the induction of suppressor cells. Reverse transcription-PCR on pancreatic tissue revealed significantly lower levels of interferon-gamma and higher levels of interleukin-4 in the combination group. In conclusion, nonhypercalcemic analogs of 1,25-dihydroxyvitamin D3 administered to NOD mice when the autoimmune disease is already active can prevent clinical diabetes when this therapy is combined with a short induction course of an immunosuppressant such as CyA.

Targeted inactivation of the mouse alpha 2-macroglobulin gene.

The mouse alpha 2-macroglobulin gene was inactivated in embryonic stem cells by homologous recombination. Liver alpha 2-macroglobulin mRNA and plasma protein was absent in homozygotes and reduced to 50% in heterozygotes. alpha 2-Macroglobulin-deficient mice were viable and produced normally sized litters with normal sex ratio over 3 generations. Characterization of adult homozygotes included diets with different fat content, treatments with endotoxin, bleomycin, carbon tetrachloride, and ethionine to test for immune system, lung, liver, and pancreas toxicity, respectively. Knock-out mice were more resistant to endotoxin but more sensitive to a choline-free diet supplemented with ethionine. Regulation of murinoglobulin mRNA expression during pregnancy was analyzed as a possible back-up mechanism for the deficiency in alpha 2-macroglobulin. In addition, expression of mRNA was studied, coding for alpha 2-macroglobulin receptor/lipoprotein receptor-related protein, low density lipoprotein receptor, and very low density lipoprotein receptor and for some common ligands, i.e. apolipoprotein E, lipoprotein lipase, and the 44-kDa heparin binding protein. Their differential regulation in the knock-out mice relative to C57B1 mice was evident and is discussed. The impressive 15-fold increase in maternal liver murinoglobulin mRNA at partum in the knock-out mice indicated increased consumption, compared to only 4-fold in normal mice. Thus, murinoglobulin appears as the major proteinase inhibitor around partum, obviously solicited to a much greater extend in alpha 2-macroglobulin-deficient mice.

Molecular cloning and sequencing of the murine alpha-2-macroglobulin receptor cDNA.

We have molecularly cloned and sequenced the mouse alpha-2-macroglobulin receptor cDNA. The cDNA contained 14849 bases with one large open reading frame of 4545 codons which is one more than in the corresponding human cDNA. Comparison of the predicted mouse and human receptor proteins revealed the very conserved nature of this receptor with an overall amino acid identity of more than 97%. A dramatic example of this is the presence of 331 cysteine residues predicted in the mouse protein, of which 327 are positionally conserved relative to human.