Interferon regulatory factor 1 is induced by interferon-gamma equally in neurons and glial cells

Class I MHC protein is induced in glia but not mature neurons by IFN-gamma. We have compared IFN-gamma signal transduction in these populations. There were identical levels of STAT1 homodimers and IRF-1 by gel-shift and IRF-1 mRNA was induced equally. However class I MHC, beta2-microglobulin and interleukin 1-beta converting enzyme mRNA levels were greatly reduced in neurons. These experiments show that there is no defect in expression of IRF-1 in response to IFN-gamma in mature mouse neurons but that insufficient class I MHC gene expression is induced for detectable cell surface protein expression.

Protection of NIT-1 pancreatic beta-cells from immune attack by inhibition of NF-kappaB

We have recently observed that inhibition of NF-kappaB in NIT-1 insulinoma cells protects them from tumour necrosis factor (TNF)-induced cell death in vitro, possibly because expression of interleukin-1 (IL-1)beta-converting enzyme (ICE), a member of the cysteine protease pathway of cell death, is decreased. In the current study we have examined the effect of the same inhibitor of NF-kappaB on class I major histocompatibility complex (MHC) protein expression in NIT-1 cells and shown that inhibition of NF-kappaB activation decreased basal and TNF-induced class I MHC levels. Although inducible nitric oxide synthase (iNOS) may also be inhibited by inhibition of NF-kappaB, this could not be demonstrated in NIT-1/delta sp cells because wild-type NIT-1 cells express very little iNOS. When NIT-1/delta sp12 cells, expressing high levels of the NF-kappaB inhibitor, are transplanted into immunodeficient NOD/scid mice, tumorigenesis and death by hypoglycemia proceed similarly to untransfected NIT-1 cells. Untransfected NIT-1 cells were killed by co-transfer of splenic T cells from diabetic but not non-diabetic NOD mice. NIT-1/delta sp12 cells were protected from killing in vivo by T cells from diabetic mice, in that tumours developed in four out of five mice and the kinetics of tumour development were not significantly delayed. NIT-1/delta sp12 cells were not protected from killing by T cells from mice previously primed with NIT-1 cells. In conclusion, inhibition of NF-kappaB is likely to suppress several different pathways of immune-mediated cell death in beta-cells and protects NIT-1 cells from immune attack by diabetogenic T cells in vivo. Inhibition of NF-kappaB is a potentially effective strategy for protection of pancreatic beta-cells in autoimmune diabetes.

Lymphocytopenia in a hospital population--what does it signify?

BACKGROUND

Lymphocytopenia is a common finding in hospital patients especially since the advent of automated differential leukocyte counters. The causes and significance of lymphocytopenia are generally poorly understood. There has been no large-scale study of its significance for 25 years. The HIV epidemic, and the recently described idiopathic CD4+ T-lymphocytopenia have raised interest in this finding.

AIMS

To describe the spectrum of lymphocytopenia in an adult teaching hospital and investigate its clinical significance.

METHODS

Using the available computer facilities, patients with significant lymphocytopenia (< 0.6 x 10(9)/L) were identified over a 102 day period and diagnoses, operations and medication lists obtained. Where necessary, patient histories were examined to supplement the above information. If feasible, previous and subsequent lymphocyte counts were checked to establish if the lymphocytopenia were temporary or longstanding.

RESULTS

One thousand and forty-two patients were identified, with a mean age of 59.6 years, of whom 563 were male, and 757 were inpatients. Thirty-six patients were pancytopenic. We checked previous and subsequent counts for 698 patients and found 45 patients who were consistently lymphocytopenic, some for more than ten years. Thirty-four patients with previously normal counts remained lymphocytopenic throughout follow up, while 457 had at least one subsequent lymphocyte count > 1 x 10(9)/L. We found only one patient who was suspected of having idiopathic CD4+ T-lymphocytopenia. Patients fell into several categories (with some overlap): bacterial/fungal sepsis (250), post-operative (228), corticosteroid therapy (definite 159, suspected 53, inhaled steroids alone 14), malignancy (174 definite, six probable), cytotoxic therapy and/or radiotherapy (90), trauma or haemorrhage (86), transplants (73-38 renal and 35 bone marrow), 'viral infections' (26) and HIV infection (13). Thirty-four patients died within the study period.

CONCLUSIONS

Lymphocytopenia in hospital patients is most frequently reversible, and due to acute illness, notably sepsis and trauma (including surgery). Malignancy, with or without chemotherapy, and steroid use are also common causes, but HIV infection is a relatively uncommon cause in our hospital.

Monozygotic twins discordant for congenital complete heart block

OBJECTIVE

Isolated congenital complete heart block (CCHB) occurs in 1/20,000 live births. More than 85% of mothers giving birth to affected infants are anti-Ro antibody positive, but only approximately 1% of babies with anti-Ro-positive mothers develop CCHB. We studied 2 sets of monozygotic twins discordant for CCHB.

METHODS

Monozygosity was determined using placental examination and DNA microsatellite analysis. HLA typing was performed. Autoantibody studies were performed using counterimmunoelectrophoresis, immunoblotting, Ro 52 and Ro 60 enzyme-linked immunosorbent assay (ELISA), and indirect immunofluorescence (IIF) on Ro 60- and Ro 52-transfected HEp-2 cells.

RESULTS

Both sets of twins were monozygotic. They had similar birth weights. Twin 2 in the second set required a pacemaker at age 2 months. Both mothers were positive for anti-Ro 52 and anti-Ro 60 antibody, and neither had anti-La antibody on immunoblot. One set of twins was studied at birth. Similar titers of anti-Ro 52 and anti-Ro 60 antibody were found by IIF and ELISA.

CONCLUSION

There are no previous well-documented reports of monozygotic twins discordant for CCHB. These cases demonstrate that there is still discordance in the development of CCHB despite identical genetics and environmental exposure to anti-Ro antibody.

Transgenic expression of mouse proinsulin II prevents diabetes in nonobese diabetic mice

IDDM in humans and in nonobese diabetic (NOD) mice is a T-cell-dependent autoimmune disease in which the beta-cells of the pancreatic islets are destroyed. Several putative beta-cell autoantigens have been identified, but insulin and its precursor, proinsulin, are the only ones that are beta-cell specific. (Pro)insulin may be a key autoantigen in IDDM. To address the role of proinsulin in the development of IDDM, we generated NOD mice transgenic for the mouse proinsulin II gene driven off a major histocompatibility complex (MHC) class II promoter to direct expression of the transgene to MHC class II bearing cells, including those in the thymus, with the aim of deleting proinsulin-reactive T-cells. The mononuclear cell infiltration of the islets (insulitis) is almost completely absent, and diabetes is prevented in these transgenic NOD mice. The mononuclear cell infiltration of the salivary glands (sialitis) and immune responses to ovalbumin (OVA) are not altered, indicating that the protective effect of the transgene is specific for islet pathology and not due to general immunosuppression. We conclude that autoimmunity to proinsulin plays a pivotal role in the development of IDDM.

RIP-beta 2-microglobulin transgene expression restores insulitis, but not diabetes, in beta 2-microglobulin null nonobese diabetic mice

Beta2m-deficient nonobese diabetic (NODbeta2mnull) do not develop insulitis or diabetes. Expression of a beta2m transgene controlled by the rat insulin promoter (RIP-beta2m) in NODbeta2mnull mice resulted in reconstitution of IFN-gamma-inducible cell surface MHC class I protein on pancreatic beta-cells. These mice developed insulitis, but did not develop diabetes. Transfer of T cells from diabetic NOD mice to NODbeta2mnull recipients resulted in insulitis, which took several months to progress to diabetes. In contrast, transgenic RIP-beta2m/NODbeta2mnull mice with islet MHC class I reconstitution developed diabetes rapidly after transfer of diabetic NOD spleen cells. Administration of cyclophosphamide, which accelerates diabetes in NOD mice, resulted in 43% of RIPbeta2m/NODbeta2mnull mice becoming diabetic compared with 75% of wild-type mice and 0% of NODbeta2mnull mice. Acceleration of diabetes by cyclophosphamide was prevented by anti-CD8 mAb treatment. FACS analysis of peripheral blood and lymphoid organs from transgene-bearing animals did not show an increase in the number of CD8+ T cells compared with that in NODbeta2mnull mice. In summary, beta-cell expression of beta2m in NODbeta2mnull mice resulted in a return of insulitis, but not spontaneous diabetes. These studies demonstrate that beta2m and cell surface MHC class I expression on beta-cells are essential for the initiation of diabetes in the NOD mouse and further confirm that efficient progression to diabetes requires both CD4+ and CD8+ T cells.

RIP-beta 2-microglobulin transgene expression restores insulitis, but not diabetes, in beta 2-microglobulin null nonobese diabetic mice

Beta2m-deficient nonobese diabetic (NODbeta2mnull) do not develop insulitis or diabetes. Expression of a beta2m transgene controlled by the rat insulin promoter (RIP-beta2m) in NODbeta2mnull mice resulted in reconstitution of IFN-gamma-inducible cell surface MHC class I protein on pancreatic beta-cells. These mice developed insulitis, but did not develop diabetes. Transfer of T cells from diabetic NOD mice to NODbeta2mnull recipients resulted in insulitis, which took several months to progress to diabetes. In contrast, transgenic RIP-beta2m/NODbeta2mnull mice with islet MHC class I reconstitution developed diabetes rapidly after transfer of diabetic NOD spleen cells. Administration of cyclophosphamide, which accelerates diabetes in NOD mice, resulted in 43% of RIPbeta2m/NODbeta2mnull mice becoming diabetic compared with 75% of wild-type mice and 0% of NODbeta2mnull mice. Acceleration of diabetes by cyclophosphamide was prevented by anti-CD8 mAb treatment. FACS analysis of peripheral blood and lymphoid organs from transgene-bearing animals did not show an increase in the number of CD8+ T cells compared with that in NODbeta2mnull mice. In summary, beta-cell expression of beta2m in NODbeta2mnull mice resulted in a return of insulitis, but not spontaneous diabetes. These studies demonstrate that beta2m and cell surface MHC class I expression on beta-cells are essential for the initiation of diabetes in the NOD mouse and further confirm that efficient progression to diabetes requires both CD4+ and CD8+ T cells.

Pancreatic expression of B7 co-stimulatory molecules in the non-obese diabetic mouse

Expression of the co-stimulatory molecule B7-1 (CD80) on pancreatic beta cells can overcome peripheral T cell tolerance in transgenic models of autoimmune disease. This study aimed to determine if aberrant B7-1 or B7-2 (CD86) expression on pancreatic beta cells is involved in the pathogenesis of autoimmune diabetes in non-obese diabetic (NOD) mice. Immunohistochemical analysis of NOD pancreas sections revealed no evidence of B7-1 or B7-2 expression on pancreatic beta cells at any stage prior to the onset of either spontaneously arising or cyclophosphamide-accelerated diabetes. Likewise, the NOD-derived NIT-1 beta cell line did not express surface B7 or B7-1 mRNA either constitutively or following exposure to IFN-gamma and TNF-alpha, two cytokines known to be present in the insulitis lesion of NOD mice, or cAMP which can induce B7-1 expression on B cells. Both B7-1 and B7-2 were, however, highly expressed on the majority of islet-infiltrating inflammatory cells in NOD mice between days 7 and 12 after the administration of cyclophosphamide which results in accelerated beta cell destruction. Likewise B7-1 and B7-2 were extensively expressed on islet-infiltrating cells present at the time of diabetes onset in NOD SCID mice with adoptively transferred diabetes. By immunohistochemistry and flow cytometry, it was determined that the phenotype of B7+ cells in the pancreas of NOD mice 9 days after cyclophosphamide included a mixture of macrophages and both CD4+ and CD8+ T cells. B7-2 was also expressed on islet-infiltrating cells in the spontaneously occurring diabetes of female NOD mice, but the levels of B7-1 expression were low in comparison with the accelerated models of diabetes. RIP-IL-2 transgenic mice, which have extensive islet infiltration but no autoimmune beta cell destruction, also had virtually no B7-1 expression and a minority of B7-2-expressing inflammatory cells. Thus, the activation of beta cell-specific T cells in NOD mice does not appear to be a result of aberrant expression of B7 on the beta cells. Expression of B7-1 and B7-2 on islet-infiltrating cells is, however, associated with autoimmune beta cell destruction, suggesting a role for the B7-CD28 interaction in this process.

Gonadotropin-releasing hormone stimulates glycoprotein hormone alpha-subunit messenger ribonucleic acid (mRNA) levels in alpha T3 cells by increasing transcription and mRNA stability

Pulsatile GnRH stimulates gonadotropin secretion, whereas continuous exposure to GnRH causes pituitary desensitization and suppressed levels of LH and FSH. At the level of gene expression, continuous GnRH also causes partial or complete suppression of the LH beta and FSH beta genes, but expression of the alpha-subunit gene is stimulated without evidence of desensitization. In this report, we examined the transcriptional and posttranscriptional mechanisms by which GnRH controls alpha-gene expression using the gonadotrope-derived alpha T3 cell line. Continuous GnRH caused a 4- to 5-fold accumulation of alpha mRNA over 72 h, without evidence of a decline. In contrast, measurements of alpha-gene transcription, either by nuclear run-on assays or using a stably integrated alpha LUC reporter gene, revealed that GnRH caused a transient increase in alpha-promoter activity, followed by a decline after 4-6 h. The prolonged accumulation of alpha mRNA at a time when transcriptional activity had abated was accounted for by independent effects of GnRH on alpha mRNA stability. After prior treatment with GnRH, its removal either by washout or using a GnRH receptor antagonist caused an abrupt decline in steady state alpha mRNA levels (t1/2, < 2 h). Readdition of GnRH prevented the decay in alpha mRNA, and experiments using the transcriptional inhibitor actinomycin-D confirmed that this effect of GnRH did not require transcription. Consistent with these results, pulse-chase analyses of mRNA stability demonstrated that GnRH increased the alpha mRNA half-life 6.7-fold, from 1.2 h in the absence of GnRH to 8.0 h in the presence of GnRH. We conclude that GnRH induces a transient burst of alpha-gene transcription that is accompanied by marked induction of mRNA stability.

Gonadotropin-releasing hormone causes transcriptional stimulation followed by desensitization of the glycoprotein hormone alpha promoter in transfected alpha T3 gonadotrope cells

Pulsatile GnRH regulates the biosynthesis and secretion of gonadotropins. Continuous administration of GnRH is known to desensitize gonadotropin secretion, but its effects on gonadotropin gene expression are less well characterized. We used a cell line of gonadotrope lineage (alpha T3 cells) to examine GnRH regulation of glycoprotein hormone alpha-subunit gene transcription. The alpha-subunit promoter, linked to a luciferase reporter gene (alpha LUC), was stably transfected into alpha T3 cells. Treatment with GnRH stimulated alpha LUC activity 3-fold. Stimulation of alpha LUC by GnRH was transient, with maximal activity after 6 h of treatment, followed by a return to baseline after 24 h. Stimulation of alpha-promoter activity by GnRH was inhibited entirely by a 10-fold molar excess of antide, a GnRH antagonist. Antide partially blocked GnRH stimulation even when added 4 h after GnRH, suggesting that a brief exposure to GnRH is not sufficient for maximal transcriptional stimulation. alpha LUC activity was also stimulated by treatment with 8-bromo-cAMP (3.5-fold), phorbol 12-myristate 13-acetate (TPA; 2.6-fold), or Bay K 8644 (3.3-fold). To assess whether the transient nature of GnRH stimulation was due to transcriptional desensitization, cells were pretreated with GnRH, followed by a second treatment with GnRH, cAMP, TPA, or Bay K. After pretreatment with GnRH, no further stimulation was seen after the addition of GnRH or TPA, but alpha LUC activity was further stimulated after the addition of either cAMP or Bay K. These findings indicate that the pathway for transcriptional activation by GnRH is desensitized and suggest that GnRH also desensitizes TPA-mediated stimulation. Similarly, pretreatment with TPA, but not cAMP or Bay K, prevented subsequent stimulation by GnRH. We conclude that GnRH transiently stimulates alpha gene transcription and that desensitization occurs with continuous exposure to GnRH, probably because of down-regulation of the protein kinase-C pathway.

Localization of promoter sequences required for thyrotropin-releasing hormone and thyroid hormone responsiveness of the glycoprotein hormone alpha-gene in primary cultures of rat pituitary cells

The glycoprotein hormone alpha-gene is regulated by multiple hormones in different pituitary and placental cell types. In thyrotropes, the alpha-gene is stimulated by TRH and repressed by thyroid hormone (T3). We used transient expression assays in primary cultures of rat pituitary cells to examine regulation of the alpha-promoter (alpha Luc) by TRH and T3. The -846 alpha Luc activity was stimulated 3.4-fold by TRH and repressed 44% by T3. GnRH and cAMP stimulated -846 alpha Luc by 8.3- and 8.6-fold, respectively. T3 blocked TRH stimulation, but it had no effect on stimulation by GnRH or cAMP, suggesting that the T3-mediated effects are thyrotrope specific. TRH and T3 responsiveness was preserved with deletions to -346 basepairs (bp). TRH responsiveness was lost after deletion to -280 bp, whereas T3-mediated repression was eliminated by further deletion to -180 bp. A series of DNA fragments between -420 and -180 was linked to -132 alpha Luc to study TRH and T3 responses in greater detail. Sequences between -346 to -180 bp conferred TRH responsiveness and T3 inhibition. TRH responsiveness was not seen after 3'-deletions of this fragment to -244 or -280 bp. These results together with the 5'-deletions provide evidence for two interdependent TRH regulatory regions: one between -346 to -280 bp and another between -244 to -180 bp. T3-dependent repression only requires sequences between -244 and -180 bp. Site-directed cluster mutations were created in each of these two regulatory domains. A mutation in region 1 (-346 to -328 bp) eliminated TRH stimulation, but retained basal suppression by T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of a gonadotropin-releasing hormone-responsive region in the glycoprotein hormone alpha-subunit promoter

Transcriptional regulation of the glycoprotein hormone alpha-subunit gene has been studied extensively in placental cells, but much less is known about its regulation in the pituitary gland. In this study, transcriptional control of the human alpha-subunit gene by GnRH was analyzed using transient expression assays in primary cultures of rat pituitary cells using alpha promoter constructs linked to a luciferase reporter gene. Deletion mutants between -846 and -156 basepairs (bp) had little effect on basal expression, but further deletion to -132 bp reduced basal activity by approximately 50%. Deletion of a cAMP response element between -132 and -99 bp caused a marked loss of basal activity, reducing expression to that of background luciferase activity. The same constructs were analyzed for cAMP responsiveness in primary pituitary cells. The degree of stimulation with 1 mM 8-bromo-cAMP (3.6- to 6.0-fold) was relatively unaffected by deletions from -846 to -132 bp, whereas cAMP stimulation was decreased by further deletion to -99 bp, consistent with the presence of previously defined cAMP response elements in this region of the alpha promoter. GnRH stimulation of alpha promoter activity was highly dependent upon the time of hormone addition after transfection, being most effective when added soon after transfection. Under optimal conditions, GnRH stimulated -846 alpha LUC expression by 20-fold. GnRH responsiveness was retained with deletion to -346 bp, but it was decreased by 55% after deletion to -280 bp and by 79% with deletion to -244 bp.(ABSTRACT TRUNCATED AT 250 WORDS)

Overexpression of class I major histocompatibility complex accompanies insulitis in the non-obese diabetic mouse and is prevented by anti-interferon-gamma antibody

Overexpression of class I major histocompatibility complex (MHC) proteins on pancreatic islet cells is a characteristic of autoimmune Type 1 (insulin-dependent) diabetes mellitus in humans and in animal models. Studies of post-mortem pancreases from humans with Type 1 diabetes suggest that overexpression of class I MHC proteins may precede mononuclear cell infiltration of the islets (insulitis). Pancreatic histology from the earliest stages of human Type 1 diabetes is rarely available. We have used the non-obese diabetic mouse, given cyclophosphamide to accelerate Beta-cell destruction, to investigate the temporal relationship between the overexpression of class I MHC protein and mRNA and other pathological changes associated with Beta-cell destruction. Prior to cyclophosphamide, immunoperoxidase staining showed that expression of class I MHC proteins was greater on islet cells and infiltrating inflammatory cells of the non-obese diabetic mouse than on islet cells of other mouse strains, whereas staining on exocrine cells was similar. On day three after cyclophosphamide administration, when insulitis had regressed, islet class I MHC protein expression had diminished. A dramatic increase in class I MHC protein expression occurred between days seven and nine, concomitant with reinfiltration of the islets by mononuclear cells; overexpression was seen both on islet cells and on surrounding exocrine cells, but only in the presence of mononuclear cell infiltration. By day 21, class I MHC protein overexpression was again confined to the islets, the exocrine pancreas being free of infiltration. Class I mRNA also increased dramatically by day eight but had virtually returned to normal by day 12.2+ effected by cytokines secreted by activated immuno-inflammatory cells. Class I MHC overexpression should enhance targeting of cytotoxic T cells to Beta cells bearing autoantigen.

Novel cyclic adenosine 3',5'-monophosphate response element in the human chorionic gonadotropin beta-subunit gene

CG is encoded by separate alpha- and beta-subunit genes. Expression of both genes is stimulated by cAMP, but the kinetics of activation are different, with cAMP stimulation of the alpha gene preceding that of the beta gene. The cAMP response element (CRE) in the alpha gene contains a palindromic DNA sequence, TGACGTCA, that binds the transcription factor CREB, a nuclear phosphoprotein that is activated by protein kinase-A. Previously, detailed characterization of a CRE in the CG beta gene had been difficult due to low levels of expression in transfected cells. In this study the 5'-flanking sequence of the CG beta gene was fused to a sensitive luciferase (LUC) reporter gene, allowing delineation of a CG beta CRE in transient expression assays performed in JEG-3 choriocarcinoma cells. The full-length CG beta promoter, -3700 to 362 basepairs (bp), was stimulated 8- to 14-fold by treatment with 1 mM 8-bromo-cAMP. Analyses of a series of deletion mutants in the CG beta promoter demonstrated that -311 CG beta LUC retained nearly complete cAMP stimulation, but deletion to -187 bp eliminated cAMP responsiveness. Overlapping DNA fragments between -311 and -30 bp were fused to a heterologous promoter (-99 alpha LUC) to further define the locations of basal elements and CREs. Basal expression required a combination of at least two distinct elements between -311 and -30 bp, whereas cAMP responsiveness was conferred by sequences between -311 and -202 bp. Shorter DNA sequences within this region were insufficient for cAMP stimulation, suggesting that more than one element may be required. DNase-I footprinting and gel mobility shift studies demonstrated at least three distinct protein-binding sites within the CG beta CRE sequence. Recombinant CREB (expressed in E. coli) did not bind to these sites, and they share no sequence homology with the alpha gene CRE, indicating that a cAMP-responsive transcription factor other than CREB interacts with the CG beta promoter.

Characterization of pancreatic T lymphocytes associated with beta cell destruction in the non-obese diabetic (NOD) mouse

Pancreatic beta cell destruction in the non-obese diabetic (NOD) mouse is mediated by T lymphocytes and macrophages and accelerated by cyclophosphamide. We purified pancreatic T lymphocytes from the NOD mouse for comparative phenotypic and functional analysis with T lymphocytes from spleen, peripheral blood and regional lymph nodes. Pancreatic T lymphocytes from NOD-Wehi mice, which have an incidence of spontaneous diabetes of less than 5%, had a CD4:CD8 ratio of 1.25 +/- 0.23 compared with 2.44 +/- 0.31 for peripheral blood lymphocytes. After cyclophosphamide, the CD4:CD8 ratio of pancreatic lymphocytes increased to 2.30 +/- 0.24 at day 7. T lymphocytes bearing IL-2 receptors increased two- to three-fold in number and their secretion of GM-CSF/IL-3 and IFN-gamma increased to a maximum on day 7. Pancreatic insulin content and mRNA levels declined sharply between days 10 and 12, at which time the majority of pancreatic T lymphocytes in hyperglycaemic mice were CD8+ (CD4:CD8 ratio 0.63 +/- 0.04 compared to 4.14 +/- 1.05 in peripheral blood). The pancreatic T lymphocyte CD4:CD8 ratio in prediabetic NOD-Lt mice, which have an incidence of spontaneous diabetes of about 60% at 150 days, was similar to that in untreated NOD-Wehi mice, but 25% of their pancreatic CD8 T lymphocytes were IL-2-receptor positive. Thus, significant changes in the phenotype of NOD pancreatic T lymphocytes following cyclophosphamide were not reflected in peripheral blood or spleen T lymphocytes. The earliest change after cyclophosphamide was an increase in activated, predominantly CD4+ T lymphocytes; with the development of beta cell destruction and hyperglycaemia, pancreatic T lymphocytes were, as in human IDDM, predominantly CD8+.

Essential role for interferon-gamma and interleukin-6 in autoimmune insulin-dependent diabetes in NOD/Wehi mice

Experimental studies in vitro suggest that cytokines are important mediators in the pathogenesis of autoimmune insulin-dependent diabetes mellitus (IDDM). However, there is little evidence for the role of cytokines in vivo, either in humans or in the spontaneous animal models of IDDM such as the NOD mouse or BB rat. To address this question, we used the model of cyclophosphamide (CYP)-induced autoimmune diabetes in the NOD/Wehi mouse to examine for (a) the production of IFN-gamma and IL-6 from isolated islets, and (b) the effect of anti IFN-gamma or anti IL-6 monoclonal antibodies on the development of diabetes. After cyclophosphamide, the majority of these mice develop of mononuclear cell infiltrate (insulitis) which by 10-14 d is associated with beta cell destruction. IFN-gamma activity at low levels (2.7 +/- 0.3 U/ml) could be detected only in culture supernatants from islets isolated at day 7 post-cyclophosphamide. In contrast, IL-6 activity progressively increased from 457 +/- 44 U/ml at day 0 to 6,020 +/- 777 U/ml at day 10. Culture of islets with anti-CD3 monoclonal antibody resulted in a significant increase in IFN-gamma activity from 41 +/- 7 U/ml at day 0 to 812 +/- 156 U/ml at day 10. Mice given either anti-IFN-gamma or anti-IL-6 antibody had a significantly reduced (P less than 0.001) incidence of diabetes and especially with IFN-gamma, decreased severity of insulitis. We conclude that IFN-gamma and IL-6 have essential roles in the pathogenesis of pancreatic islet beta cell destruction in this model.

Murine models of autoimmune diabetes: nonspecific cytotoxic lymphocytes derived from pancreatic islets in the presence of IL-2

Our aim was to derive T lymphocyte lines that specifically recognize islet antigens in murine models of autoimmune diabetes. Islets of Langerhans infiltrated with lymphocytes were isolated either from mice previously injected with multiple low doses of streptozotocin or from NOD-WEHI mice and were cultured in the presence of the T cell growth factor, interleukin 2 (IL-2). With islets from both models of autoimmune diabetes, rapidly proliferating, large granular lymphocytes emerged after 7-10 days and destroyed the islets and other cells such as fibroblasts in the cultures. Cytotoxicity assays showed that these cells were capable of destroying both P815 and YAC-1 tumor cells. In contrast to lymphocytes present initially in the islet infiltrates which express predominantly the L3T4 marker, the large granular lymphocytes were shown to be Ly-2 positive. They also expressed the alpha beta T cell receptor and contained mRNA for the alpha beta T cell receptor demonstrable by in situ hybridization. While morphologically similar to NK cells these large granular lymphocytes bear T cell markers and destroy a broader range of targets. They may represent a minor population of T lymphocytes particularly responsive to IL-2 although other studies show that T cells generally can develop a similar phenotype after prolonged culture with IL-2. The lack of target cell specificity indicates that these IL-2-stimulated large granular lymphocytes are unlikely to mediate the immunopathogenesis of diabetes in these animal models.

Determinants of restenosis and lack of effect of dietary supplementation with eicosapentaenoic acid on the incidence of coronary artery restenosis after angioplasty

The effect of an eicosapentaenoic acid-rich encapsulated preparation of fish oil on the incidence of early restenosis after coronary angioplasty was assessed by a randomized double-blind placebo-controlled study. A total of 108 patients received either 10 capsules of fish oil (1.8 g eicosapentaenoic acid, 1.2 g docosahexaenoic acid) or 10 control capsules (50% olive oil, 50% corn oil), commencing the day before angioplasty and continuing for 4 months after angioplasty, in addition to treatment with aspirin and verapamil. In 101 (94%) of the 108 patients, follow-up angiographic or postmortem result was evaluated at a mean (+/- SD) of 100 (+/- 22) days. Angiographic restenosis was observed in 34% of patients (29% of lesions) in the fish oil-treated group and 33% of patients (31% of lesions) in the control group (no significant difference). The overall incidence of angiographic restenosis was significantly higher in patients with 1) recurrent angina pectoris, 2) a positive exercise test at follow-up after angioplasty, 3) residual stenosis greater than 30% immediately after angioplasty, and 4) dilation of the left anterior descending or right coronary artery. Biochemical investigations showed a greater decrease in the serum triglyceride levels in the fish oil-treated group versus the control group (p less than 0.05) but no differences between the two groups in cholesterol levels or platelet counts over the 4 month period. In conclusion, in this study, the administration of fish oil at a dose of 10 capsules/day did not reduce the incidence of early restenosis after coronary angioplasty.

Treatment of non-toxic multinodular goiter with radioactive iodine

Fourteen patients with large non-toxic multinodular goiters were treated with 20 to 100 mCi (740 to 3,700 MBq) of radioactive iodine (iodine-131). In seven, the goiter had recurred after a partial thyroidectomy and four of these had had two operations. Eight had symptoms of respiratory obstruction, two had dysphagia, and the others sought treatment for cosmetic reasons. After administration of iodine-131, there was a significant decrease in goiter size in 11 of the 14 patients, and all those with obstructive symptoms showed improvement. No significant local side effects occurred, but hypothyroidism and Graves' disease each occurred once during follow-up from one to 13 years. Radioactive iodine in doses of 20 to 100 mCi is an effective, safe therapeutic alternative in patients with large non-toxic multinodular goiter, particularly when there is recurrence following surgery or when there are contraindications to surgery.

64,000-Mr autoantigen in type I diabetes. Evidence against its surface location on human islets

The sera of type I (insulin-dependent) diabetic subjects are reported to contain autoantibodies against a 64,000-Mr protein identified in [35S]methionine biosynthetically labeled pancreatic islet cells. We have attempted to localize this autoantigen to the surface of the beta-cell and to define its properties. Sera from 10 newly diagnosed type I diabetic subjects, including five of the index sera originally used to identify the autoantigen, were shown to specifically precipitate a reduced protein of 67,000 Mr from Triton-solubilized, surface 125I-labeled cultured adult human islet and rat insulinoma (RINm5F) cells but not from fresh rat spleen cells. Further characterization revealed that this protein was bovine serum albumin (BSA) adsorbed to cells from fetal calf serum (FCS)-supplemented culture medium and precipitated by BSA antibodies present in many diabetic sera. No labeled proteins were specifically precipitated when surface 125I-labeled and solubilized human islet or RINm5F cells were precleared with anti-BSA immunoglobulins or when cells were first cultured in human serum. In contrast, a 64,000-Mr protein, clearly not BSA, was precipitated by diabetic globulins from human islets but not from RINm5F cells labeled with [35S]methionine. In addition, a protein of the same size as well as proteins of approximately 35,000, 43,000, 140,000, and 200,000 Mr were specifically precipitated by diabetic globulins from freshly isolated human islets solubilized in Triton X-100 and then labeled with 125I. These findings suggest that the 64,000-Mr antigen is not expressed on the surface of human islet cells, at least in culture, and therefore question its relevance as a target for islet cell surface antibodies in initiating beta-cell damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Heel ulcers in patients with long-standing diabetes who wear antiembolism stockings

Four patients with long-standing insulin-dependent diabetes mellitus developed heel ulceration while wearing correctly fitted antiembolism stockings after major surgery. These patients all had evidence of peripheral vascular disease and peripheral neuropathy. Heel ulceration appears to be a significant side-effect of this form of prophylaxis against venous thromboembolism in patients with long-standing diabetes mellitus. The use of antiembolism stockings in such patients, who are likely to have vascular and neurological impairment, should be undertaken with great care, if at all.

Relative sensitivity of fetal and newborn mice to induction of hapten-specific B cell tolerance

Mice were rendered tolerant to the hapten fluorescein (FLU) by a single injection of FLU-human gamma globulin (FLU5HGG) 2-3 d after birth or via the maternal circulation at 14.5 d of fetal life. After 7-9 d, the degree of functional nonresponsiveness induced in vivo among splenic FLU-specific B cells of tolerized mice was assessed by limiting-dilution analysis in vitro, and the serum levels of trace-labeled tolerogen were determined. When tolerogen was introduced before the appearance of any B cells, and was thus present during the pre-B to B cell transition stage, a concentration of 5.4 x 10(-13) M effectively silenced 50% of the clonable anti-FLU PFC precursors; but a similar reduction on newborns required a minimal tolerogen concentration of 1.3 x 10(-10) M, > 300-fold less than has previously been shown to equally affect adult B cells, but at least 240-fold more than in the in utero situation. Neonatally induced tolerance using a relatively high tolerogen dose lasted approximately 12 wk.