Human multipotent adult progenitor cells enhance islet function and revascularisation when co-transplanted as a composite pellet in a mouse model of diabetes

AIMS/HYPOTHESIS

Hypoxia in the initial days after islet transplantation leads to considerable loss of islet mass and contributes to disappointing outcomes in the clinical setting. The aim of the present study was to investigate whether co-transplantation of human non-endothelial bone marrow-derived multipotent adult progenitor cells (MAPCs), which are non-immunogenic and can secrete angiogenic growth factors during the initial days after implantation, could improve islet engraftment and survival.

METHODS

Islets (150) were co-transplanted, with or without human MAPCs (2.5 × 10⁵) as separate or composite pellets, under the kidney capsule of syngeneic alloxan-induced diabetic C57BL/6 mice. Blood glucose levels were frequently monitored and IPGTTs were carried out. Grafts and serum were harvested at 2 and 5 weeks after transplantation to assess outcome.

RESULTS

Human MAPCs produced high amounts of angiogenic growth factors, including vascular endothelial growth factor, in vitro and in vivo, as demonstrated by the induction of neo-angiogenesis in the chorioallantoic membrane assay. Islet-human MAPC co-transplantation as a composite pellet significantly improved the outcome of islet transplantation as measured by the initial glycaemic control, diabetes reversal rate, glucose tolerance and serum C-peptide concentration compared with the outcome following transplantation of islets alone. Histologically, a higher blood vessel area and density in addition to a higher vessel/islet ratio were detected in recipients of islet-human MAPC composites.

CONCLUSIONS/INTERPRETATION

The present data suggest that co-transplantation of mouse pancreatic islets with human MAPCs, which secrete high amounts of angiogenic growth factors, enhance islet graft revascularisation and subsequently improve islet graft function.

A proteomic approach on the effects of TX527, a 1α,25-dihydroxyvitamin D3 analog, in human T lymphocytes

1α,25-Dihydroxyvitamin D3 (1α,25(OH)2D3), and its analogs (i.e. 14,20-bis-epi-19-nor-23-yne-1α,25(OH)2D3 - TX527) have been shown to prevent autoimmunity and prolong islet graft survival in the non-obese diabetic (NOD) mouse. Their effects are mediated by their action on various immune cell types, such as dendritic cells (DC) and T cells. We have previously reported important direct effects of TX527 on human T cells, on their cytokine/chemokine profiles, T regulatory cell markers, homing characteristics and chemotaxis. In order to fully understand the molecular mechanisms underlying the beneficial properties of TX527 on human T cells, we applied here 2-dimensional difference gel electrophoresis (2-D DIGE) to analyze the global protein alterations induced by TX527 on human synchronized T cells. We detected differential expression of 64 protein spots upon TX527 treatment, of which 65.6% could be successfully identified using tandem mass spectrometry (MALDI-TOF/TOF). The identified proteins function in various processes, such as metabolism and energy pathways, cytoskeleton and protein metabolism. When comparing the proteomics data to our previously performed microarray data on the same set of cells, we found an overlap of 17 different mRNAs/proteins. For some of these (e.g. PSME2, HSPA8), the direction of regulation was not similar, hereby reinforcing the important role of post-transcriptional/translational processes in the functionality of proteins. In addition, although 2-D DIGE offers the possibility of picking up post-translational processes, it lacks the ability to detect molecules with extreme molecular weight (MW) and isoelectrical point (pI) values, or very low abundant/hydrophobic proteins. This study highlights therefore the importance of combining different experimental approaches to obtain a complete picture of the underlying mechanisms and general processes being affected in T cells upon TX527 treatment. These processes lead altogether to the generation of T cells with interesting immunomodulatory features for clinical applications in the treatment of autoimmune diseases or in the prevention of graft rejection. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

Discovery of molecular pathways mediating 1,25-dihydroxyvitamin D3 protection against cytokine-induced inflammation and damage of human and male mouse islets of Langerhans

Protection against insulitis and diabetes by active vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), in nonobese diabetic mice has until now mainly been attributed to its immunomodulatory effects, but also protective effects of this hormone on inflammation-induced β-cell death have been reported. The aim of this study was to clarify the molecular mechanisms by which 1,25(OH)2D3 contributes to β-cell protection against cytokine-induced β-cell dysfunction and death. Human and mouse islets were exposed to IL-1β and interferon-γ in the presence or absence of 1,25(OH)2D3. Effects on insulin secretion and β-cell survival were analyzed by glucose-stimulated insulin release and electron microscopy or Hoechst/propidium iodide staining, respectively. Gene expression profiles were assessed by Affymetrix microarrays. Nuclear factor-κB activity was tested, whereas effects on secreted chemokines/cytokines were confirmed by ELISA and migration studies. Cytokine exposure caused a significant increase in β-cell apoptosis, which was almost completely prevented by 1,25(OH)2D3. In addition, 1,25(OH)2D3 restored insulin secretion from cytokine-exposed islets. Microarray analysis of murine islets revealed that the expression of approximately 4000 genes was affected by cytokines after 6 and 24 hours (n = 4; >1.3-fold; P < .02), of which nearly 250 genes were modified by 1,25(OH)2D3. These genes belong to functional groups involved in immune response, chemotaxis, cell death, and pancreatic β-cell function/phenotype. In conclusion, these findings demonstrate a direct protective effect of 1,25(OH)2D3 against inflammation-induced β-cell dysfunction and death in human and murine islets, with, in particular, alterations in chemokine production by the islets. These effects may contribute to the beneficial effects of 1,25(OH)2D3 against the induction of autoimmune diabetes.

IL-17A increases the expression of proinflammatory chemokines in human pancreatic islets

AIMS/HYPOTHESIS

Cytotoxic T cells and macrophages contribute to beta cell destruction in type 1 diabetes at least in part through the production of cytokines such as IL-1β, IFN-γ and TNF-α. We have recently shown the IL-17 pathway to be activated in circulating T cells and pancreatic islets of type 1 diabetes patients. Here, we studied whether IL-17A upregulates the production of chemokines by human pancreatic islets, thus contributing to the build-up of insulitis.

METHODS

Human islets (from 18 donors), INS-1E cells and islets from wild-type and Stat1 knockout mice were studied. Dispersed islet cells were left untreated, or were treated with IL-17A alone or together with IL-1β+IFN-γ or TNF-α+IFN-γ. RNA interference was used to knock down signal transducer and activator of transcription 1 (STAT1). Chemokine expression was assessed by quantitative RT-PCR, ELISA and histology. Cell viability was evaluated with nuclear dyes.

RESULTS

IL-17A augmented IL-1β+IFN-γ- and TNF-α+IFN-γ-induced chemokine mRNA and protein expression, and apoptosis in human islets. Beta cells were at least in part the source of chemokine production. Knockdown of STAT1 in human islets prevented cytokine- or IL-17A+cytokine-induced apoptosis and the expression of particular chemokines, e.g. chemokine (C-X-C motif) ligands 9 and 10. Similar observations were made in islets isolated from Stat1 knockout mice.

CONCLUSIONS/INTERPRETATION

Our findings indicate that IL-17A exacerbates proinflammatory chemokine expression and secretion by human islets exposed to cytokines. This suggests that IL-17A contributes to the pathogenesis of type 1 diabetes by two mechanisms, namely the exacerbation of beta cell apoptosis and increased local production of chemokines, thus potentially aggravating insulitis.

Glucagon-like peptide-1: modulator of β-cell dysfunction and death

Glucagon-like peptide-1 (GLP-1) is one of the hormones responsible for the incretin effect, a term that refers to the observation that orally administered glucose results in a larger increase in plasma insulin levels and insulin-dependent decrease in blood glucose concentration when compared to the same amount of glucose given intravenously. GLP-1 is secreted mainly by gut endocrine L-cells and is released under the control of carbohydrates, proteins and lipids. Upon secretion, GLP-1 targets different cell types and exerts a wide variety of actions such as potentiation of glucose-stimulated insulin secretion, reduction of appetite, delay of gastric emptying and increase in β-cell mass. These beneficial effects have resulted in the application of GLP-1-based therapies in patients with type 2 diabetes, but also exploitation of its effects in type 1 diabetes is being envisaged. In this review, we focus on the different, short- and long-term action mechanisms of GLP-1 with specific emphasis on its role as a modulator of β-cell function and survival.

Unraveling the effects of 1,25OH2D3 on global gene expression in pancreatic islets

INTRODUCTION

Vitamin D deficiency has been linked to type 1 and 2 diabetes, whereas supplementation may prevent both diseases. However, the extent of the effects of vitamin D or its metabolites directly on pancreatic islets is still largely unknown. The aim of the present study was to investigate how active vitamin D, 1,25(OH)2D3, affects beta cells directly by establishing its effects on global gene expression in healthy murine islets.

MATERIALS AND METHODS

Pancreatic islets were isolated from 2 to 3 week old C57BL/6 mice and cultured in vitro with 1,25(OH)2D3 or vehicle for 6 and 24h. Total RNA was extracted from the islets and the effects on global gene expression were analyzed using Affymetrix microarrays.

RESULTS AND DISCUSSION

Exposure to 1,25(OH)2D3 compared to vehicle resulted in 306 and 151 differentially expressed genes after 6 and 24h, respectively (n=4, >1.3-fold, p<0.02). Of these 220 were up-regulated, whereas 86 displayed a decreased expression after 6h. Furthermore, expression levels were increased for 124 and decreased for 27 genes following 24h of exposure. Formation of intercellular junctions, cytoskeletal organization, and intracellular trafficking as well as lipid metabolism and ion transport were among the most affected gene classes. Effects on several genes already identified as being part of vitamin D signaling in other cell types were observed along with genes known to affect insulin release, although with our assay we were not able to detect any effects of 1,25(OH)2D3 on glucose-stimulated insulin release from healthy pancreatic islets.

CONCLUSION

The effects of 1,25(OH)2D3 on the expression of cytoskeletal and intracellular trafficking genes along with genes involved in ion transport may influence insulin exocytosis. However, an effect of 1,25(OH)2D3 on insulin release could not be detected for healthy islets in contrast to islets subjected to pathological conditions such as cytokine exposure and vitamin D deficiency as suggested by other studies. Thus, in addition to previously identified tolerogenic effects on the immune system, 1,25(OH)2D3 may affect basic functions of pancreatic beta cells, with the potential to render them more resistant to the detrimental conditions encountered during type 1 and 2 diabetes. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Deletion of C/EBP homologous protein (Chop) in C57Bl/6 mice dissociates obesity from insulin resistance

AIMS/HYPOTHESIS

Endoplasmic reticulum (ER) stress has been implicated in the development of type 2 diabetes, via effects on obesity, insulin resistance and pancreatic beta cell health. C/EBP homologous protein (CHOP) is induced by ER stress and has a central role in apoptotic execution pathways triggered by ER stress. The aim of this study was to characterise the role of CHOP in obesity and insulin resistance.

METHODS

Metabolic studies were performed in Chop ( -/- ) and wild-type C57Bl/6 mice, and included euglycaemic-hyperinsulinaemic clamps and indirect calorimetry. The inflammatory state of liver and adipose tissue was determined by quantitative RT-PCR, immunohistology and macrophage cultures. Viability and absence of ER stress in islets of Langerhans was determined by electron microscopy, islet culture and quantitative RT-PCR.

RESULTS

Systemic deletion of Chop induced abdominal obesity and hepatic steatosis. Despite marked obesity, Chop ( -/- ) mice had preserved normal glucose tolerance and insulin sensitivity. This discrepancy was accompanied by lower levels of pro-inflammatory cytokines and less infiltration of immune cells into fat and liver.

CONCLUSIONS/INTERPRETATION

These observations suggest that insulin resistance is not induced by fat accumulation per se, but rather by the inflammation induced by ectopic fat. CHOP may play a key role in the crosstalk between excessive fat deposition and induction of inflammation-mediated insulin resistance.

Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) impairs the regulation of apoptosis in megakaryocytes by activating NF-κB: a proteomic study

We previously showed that the Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and its receptor VPAC1 are negative regulators of megakaryopoiesis and platelet function, but their downstream signaling pathway that inhibits this process still remained unknown. A combined proteomic, transcriptomic, and bioinformatic approach was here used to elucidate the molecular mechanisms underlying PACAP signaling via VPAC1 in megakaryocytes. Two-dimensional difference gel electrophoresis and tandem MS were applied to detect differentially expressed proteins in megakaryocytic CHRF cells stimulated with PACAP. The majority of the 120 proteins modulated by PACAP belong to the class of "cell cycle and apoptosis" proteins. The up- or down-regulated expression of some proteins was confirmed by immunoblot and immunohistochemical analysis. A meta-analysis of our data and 12 other published studies was performed to evaluate signaling pathways involved in different cellular models of PACAP response. From 2384 differentially expressed genes/proteins, 83 were modulated by PACAP in at least three independent studies and Ingenuity Pathway Analysis further identified apoptosis as the highest scored network with NF-κB as a key-player. PACAP inhibited serum depletion-induced apoptosis of CHRF cells via VPAC1 stimulation. In addition, PACAP switched on NF-κB dependent gene expression since higher nuclear levels of the active NF-κB p50/p65 heterodimer were found in CHRF cells treated with PACAP. Finally, a quantitative real time PCR apoptosis array was used to study RNA from in vitro differentiated megakaryocytes from a PACAP overexpressing patient, leading to the identification of 15 apoptotic genes with a 4-fold change in expression and Ingenuity Pathway Analysis again revealed NF-κB as the central player. In conclusion, our findings suggest that PACAP interferes with the regulation of apoptosis in megakaryocytes, probably via stimulation of the NF-κB pathway.

1,25-dihydroxyvitamin D3 and a superagonistic analog in combination with paclitaxel or suberoylanilide hydroxamic acid have potent antiproliferative effects on anaplastic thyroid cancer

Anaplastic thyroid cancer represents one of the most aggressive cancers. The active form of vitamin D, 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), has been shown to have antiproliferative and/or redifferentiating properties in several malignancies, including thyroid cancer. The objective of this study was to investigate the effects of 1,25(OH)(2)D(3) and the superagonistic analog CD578 in anaplastic thyroid cancer, alone or in combination with paclitaxel, a taxane, and suberoylanilide hydroxamic acid (SAHA), a potent histone deacetylase inhibitor with promising effects in undifferentiated thyroid cancer. Four human thyroid cancer cell lines (FTC-133, C643, 8505C and HTh74) were treated with 1,25(OH)(2)D(3) or CD578, alone or in combination with paclitaxel or SAHA. Effects on cell growth and differentiation were evaluated. Clear effects on growth arrest were observed in a clonogenic assay, and absolute cell counts demonstrated a 24-36% reduction in all cell lines after 72h treatment with 1,25(OH)(2)D(3) (10(-6)M) and a 60% inhibition after 120h in the most sensitive cell line HTh74. A similar growth inhibition was shown after treatment with a 1000-fold lower concentration of analog CD578. This growth arrest was explained by antiproliferative effects, further supported by an increased % of cells in the G(0)-G(1) phase of the cell cycle and by a decreased transcription factor E2F1 mRNA expression. Combination treatments of 1,25(OH)(2)D(3) or CD578 with paclitaxel or SAHA resulted in an additive and in some conditions a synergistic effect on the inhibition of proliferation. Redifferentiation analysis revealed only a modest increase in sodium iodide symporter and thyroglobulin mRNA expression after treatment with 1,25(OH)(2)D(3), without additive effect after combination treatment. No effects were observed on TSH-receptor or thyroid peroxidase mRNA expression. Our in vitro findings demonstrate that the superagonistic vitamin D analog CD578 holds promise as adjuvant antiproliferative therapy of anaplastic thyroid cancer, especially in combination with other drugs such as paclitaxel or SAHA.

Platelet Gs hypofunction and abnormal morphology resulting from a heterozygous RGS2 mutation

SUMMARY BACKGROUND

Regulator of G-protein signaling (RGS) 2 negatively regulates Gs signaling by inhibiting the activation of adenylyl cyclase (AC). RGS2 mRNA contains four translation initiation sites, leading to four isoforms with different abilities to inhibit AC activity; the largest isoform is the most pronounced inhibitor. A role for RGS2 in platelets is not known.

OBJECTIVE

To describe a heterozygous RGS2 mutation (G23D) in three related patients, leading to Gs hypofunction in their platelets, and to study the mechanism behind the effect of the RGS2 mutation on platelet function and morphology.

METHODS

Gs signaling was studied ex vivo in platelets and in vitro in transfected cells. Translation initiation was evaluated in vitro, and the interaction of wild-type and G23D RGS2 with AC was unraveled via immunoprecipitation. Platelet granule content was analyzed with proteomics.

RESULTS

The mutation leads to reduced cAMP production after stimulation of Gs-coupled receptors. The largest RGS2 isoforms, with strong AC inhibitor activity, are enriched when the mutation is present, as compared with wild-type RGS2. Moreover, the mutation results in a stronger interaction of RGS2 with AC. G23D RGS2 carriers have enlarged, round platelets with abnormal alpha-granules. Proteomics of the platelet releasate revealed altered expression of some proteins involved in actin assembly, and carriers seemed to have a reduced platelet shape change.

CONCLUSIONS

We present the first platelet Gs signaling defect caused by a heterozygous RGS2 variant that results in a unique mutational mechanism, such as the differential use of translation initiation sites resulting in different functional RGS2 isoforms.

Interferon regulatory factor-1 is a key transcription factor in murine beta cells under immune attack

AIMS/HYPOTHESIS

IFN-gamma, together with other inflammatory cytokines such as IL-1beta and TNF-alpha, contributes to beta cell death in type 1 diabetes. We analysed the role of the transcription factor interferon regulatory factor (IRF)-1, a downstream target of IFN-gamma/signal transducer and activator of transcription (STAT)-1, in immune-mediated beta cell destruction.

METHODS

Islets from mice lacking Irf-1 (Irf-1 (-/-)) and control C57BL/6 mice were transplanted in overtly diabetic NOD mice. Viability and functionality of islets were evaluated in vitro. Chemokine expression by Irf-1 (-/-) islets and INS-1E cells transfected with Irf-1 short interfering RNA (siRNA) was measured by real-time PCR as well as in functional assays in vitro.

RESULTS

IRF-1 deletion in islets was associated with higher prevalence of primary non-function (63% vs 25%, p <or= 0.05) and shorter functioning graft survival (6.0 +/- 2.6 vs 10.4 +/- 4.8 days, p <or= 0.05) in contrast to similar skin graft survival. Although Irf-1 (-/-) islets were resistant to cytokine-induced cell death, insulin secretion by them was lower than that of control C57BL/6 islets under medium and cytokine conditions. IL-1 receptor antagonist partly restored the cytokine-induced secretory defect in vitro and completely prevented primary non-function in vivo. Cytokine-exposed Irf-1 (-/-) islets and INS-1E cells transfected with Irf-1 siRNA showed increased expression of Mcp-1 (also known as Ccl2), Ip-10 (also known as Cxcl10), Mip-3alpha (also known as Ccl20) and Inos (also known as Nos2) mRNA and elevated production of monocyte chemoattractant protein-1 (MCP-1) and nitrite compared with controls. In vivo, Irf-1 (-/-) islets displayed a higher potential to attract immune cells, reflected by more aggressive immune infiltration in the grafted islets.

CONCLUSIONS/INTERPRETATION

These data indicate a key regulatory role for IRF-1 in insulin and chemokine secretion by pancreatic islets under inflammatory attack.

Cluster analysis of rat pancreatic islet gene mRNA levels after culture in low-, intermediate- and high-glucose concentrations

AIMS/HYPOTHESIS

Survival and function of insulin-secreting pancreatic beta cells are markedly altered by changes in nutrient availability. In vitro, culture in 10 rather than 2 mmol/l glucose improves rodent beta cell survival and function, whereas glucose concentrations above 10 mmol/l are deleterious.

METHODS

To identify the mechanisms of such beta cell plasticity, we tested the effects of 18 h culture at 2, 5, 10 and 30 mmol/l glucose on the transcriptome of rat islets pre-cultured for 1 week at 10 mmol/l glucose using Affymetrix Rat 230 2.0 arrays.

RESULTS

Culture in either 2-5 or 30 mmol/l instead of 10 mmol/l glucose markedly impaired beta cell function, while little affecting cell survival. Of about 16,000 probe-sets reliably detected in islets, some 5,000 were significantly up- or downregulated at least 1.4-fold by glucose. Analysis of these probe-sets with GeneCluster software identified ten mRNA profiles with unidirectional up- or downregulation between 2 and 10, 2 and 30, 5 and 10, 5 and 30 or 10 and 30 mmol/l glucose. It also identified eight complex V-shaped or inverse V-shaped profiles with a nadir or peak level of expression in 5 or 10 mmol/l glucose. Analysis of genes belonging to these various clusters using Onto-express and GenMAPP software revealed several signalling and metabolic pathways that may contribute to induction of beta cell dysfunction and apoptosis after culture in low- or high- vs intermediate-glucose concentration.

CONCLUSIONS/INTERPRETATION

We have identified 18 distinct mRNA profiles of glucose-induced changes in islet gene mRNA levels that should help understand the mechanisms by which glucose affects beta cell survival and function under states of chronic hypo- or hyperglycaemia.

Initiation and execution of lipotoxic ER stress in pancreatic beta-cells

Free fatty acids (FFA) cause apoptosis of pancreatic beta-cells and might contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum (ER) stress. We studied here the molecular mechanisms implicated in FFA-induced ER stress initiation and apoptosis in INS-1E cells, FACS-purified primary beta-cells and human islets exposed to oleate and/or palmitate. Treatment with saturated and/or unsaturated FFA led to differential ER stress signaling. Palmitate induced more apoptosis and markedly activated the IRE1, PERK and ATF6 pathways, owing to a sustained depletion of ER Ca(2+) stores, whereas the unsaturated FFA oleate led to milder PERK and IRE1 activation and comparable ATF6 signaling. Non-metabolizable methyl-FFA analogs induced neither ER stress nor beta-cell apoptosis. The FFA-induced ER stress response was not modified by high glucose concentrations, suggesting that ER stress in primary beta-cells is primarily lipotoxic, and not glucolipotoxic. Palmitate, but not oleate, activated JNK. JNK inhibitors reduced palmitate-mediated AP-1 activation and apoptosis. Blocking the transcription factor CHOP delayed palmitate-induced beta-cell apoptosis. In conclusion, saturated FFA induce ER stress via ER Ca(2+) depletion. The IRE1 and resulting JNK activation contribute to beta-cell apoptosis. PERK activation by palmitate also contributes to beta-cell apoptosis via CHOP.

Endometrial and peritoneal expression of aromatase, cytokines, and adhesion factors in women with endometriosis

OBJECTIVE

To examine messenger (m) RNA expression of aromatase, cytokines, and adhesion factors in women with and without endometriosis.

DESIGN

Patients with endometriosis were compared with control patients.

SETTING

University Hospital Gasthuisberg, Leuven, Belgium.

PATIENT(S)

A total of 35 patients who had laparoscopic surgery during the luteal phase (n = 20) or the menstrual phase (n = 15) were selected for this study based on cycle phase and presence/absence of endometriosis.

INTERVENTION(S)

Tissues of endometrium and macroscopically normal peritoneum were collected during hysteroscopy and laparoscopic surgery, respectively, from 24 women with revised American Society for Reproductive Medicine stage (rASRM) stages I-II (n = 12) and III-IV (n = 12) endometriosis and 11 control patients with normal pelvic. Tissue samples were selected from a tissue bank, based on the phase of the cycle (menstrual or luteal) and the presence/absence of endometriosis.

MAIN OUTCOME MEASURE(S)

The mRNA levels of aromatase, vimentin, vascular cell adhesion molecule 1 (VCAM-1), alpha(V) and beta(3) integrins, interleukin (IL)-1 beta, regulated on activation normal T-cell expressed and secreted (RANTES), and monocyte chemotactic protein 1 (MCP-1) were evaluated using real-time reverse transcriptase polymerase chain reaction.

RESULT(S)

During menstrual phase, increased endometrial mRNA levels of alpha(V) integrin, combined alpha(V)beta(3) integrins, and increased peritoneal IL-1 beta mRNA levels--but decreased peritoneal MCP-1 mRNA levels--were observed in women with endometriosis compared with control subjects. During luteal phase, endometrial mRNA levels of IL-1 beta and RANTES were increased in women with endometriosis compared with control subjects. Endometrial aromatase mRNA expression was higher in women with endometriosis than in control subjects in combined phases. Women with endometriosis had increased peritoneal mRNA expression of RANTES and VCAM-1 during menstrual compared with luteal phase.

CONCLUSION(S)

Aberrant mRNA expression of aromatase, cytokines, and adhesion factors in endometrium and peritoneum suggests that both tissues are involved in the pathogenesis of endometriosis.

Unaltered diabetes presentation in NOD mice lacking the vitamin D receptor

OBJECTIVE

Vitamin D deficiency increases risk for type 1 diabetes in genetically predisposed individuals, while high doses of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] prevent insulitis and diabetes in NOD mice.

RESEARCH DESIGN AND METHODS

Since 1,25(OH)(2)D(3) regulates gene transcription through the vitamin D receptor (VDR), we investigated the role of VDR in diabetes development by creating NOD mice without functional VDR.

RESULTS

VDR(-/-) NOD mice are rachitic and have lower numbers of putative regulator cells [TCR-alpha/beta(+)CD4(-)CD8(-) (natural killer T-cells) and CD4(+)CD25(+) T-cells [in central and peripheral immune organs compared with VDR(+/+) NOD littermates. Lipopolysaccharide-stimulated VDR(-/-) NOD macrophages expressed lower interleukin (IL)-1, IL-6, and CC chemokine ligand 2 mRNA, correlating with less nuclear translocation of p65 nuclear factor-kappaB compared with VDR(+/+) NOD macrophages. Thymic and lymph node dendritic cells from VDR(-/-) NOD mice displayed an even less mature CD11c(+)CD86(+) phenotype than VDR(+/+) NOD mice. Despite this immune phenotype linked to diabetes in NOD mice, VDR(-/-) NOD mice developed insulitis and diabetes at the same rate and incidence as VDR(+/+) NOD littermates.

CONCLUSIONS

Despite aggravating known immune abnormalities in NOD mice, disruption of VDR does not alter disease presentation in NOD mice in contrast to the more aggressive diabetes presentation in vitamin D-deficient NOD mice.

Deletion of STAT-1 pancreatic islets protects against streptozotocin-induced diabetes and early graft failure but not against late rejection

OBJECTIVE

Exposure of beta-cells to inflammatory cytokines leads to apoptotic cell death through the activation of gene networks under the control of specific transcription factors, such as interferon-gamma-induced signal transducer and activator of transcription (STAT)-1. We previously demonstrated that beta-cells lacking STAT-1 are resistant to cytokine-induced cell death in vitro. The aim of this study was to investigate the effect of STAT-1 elimination on immune-mediated beta-cell destruction in vivo.

RESEARCH DESIGN AND METHODS

Multiple low-dose streptozotocin (STZ) was given to C57BL/6 mice after syngeneic STAT-1(-/-) or wild-type islet transplantation. STAT-1(-/-) and wild-type islets were also transplanted in alloxan-diabetic BALB/c and spontaneously diabetic nonobese diabetic (NOD) mice. Additionally, mice were treated with interleukin (IL)-1 blockade (IL-1 receptor antagonist [IL-1ra]) and low-dose T-cell suppression (cyclosporine A [CsA]).

RESULTS

When exposed to multiple low-dose STZ in an immune-competent host, STAT-1(-/-) islets were more resistant to destruction than wild-type islets (28 vs. 100% diabetes incidence, P < or = 0.05). STAT-1 deletion also protected allogeneic islet grafts against primary nonfunction in autoimmune NOD mice (0 vs. 17% using wild-type islets). However, no difference in survival time was observed. Additionally, treating recipients with IL-1ra and CsA prolonged graft survival in chemically diabetic BALB/c mice, whereas no difference was seen between STAT-1(-/-) and C57BL/6 grafts.

CONCLUSIONS

These data indicate that STAT-1 is a key player in immune-mediated early beta-cell dysfunction and death. When considering the many effector mechanisms contributing to beta-cell death following islet transplantation, multiple combined interventions will be needed for prolongation of beta-cell survival in the autoimmune context of type 1 diabetes.

Immune regulation of 1alpha-hydroxylase in murine peritoneal macrophages: unravelling the IFNgamma pathway

The activated form of vitamin D(3), 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), plays an important role in the immune system. Indeed, receptors for 1,25(OH)(2)D(3) are found on most immune cells, and 1alpha-hydroxylase, the enzyme responsible for final activation of vitamin D(3), is expressed by monocytes/macrophages, resulting in secretion of 1,25(OH)(2)D(3) after immune stimulation. We have previously shown that in murine peritoneal macrophages 1alpha-hydroxylase is highly regulated by immune signals such as IFNgamma and LPS. In the present study we made use of two different knock-out mouse models with disruptions in two key transcription factors in the IFNgamma-signalling cascade (STAT1alpha and IRF1), to evaluate their role in the regulation of 1alpha-hydroxylase. This was performed by culturing peritoneal macrophages from these knock-out mice in the presence of IFNgamma and LPS, and evaluating the impact of the absence of the respective transcription factors on 1alpha-hydroxylase mRNA expression by real-time RT-PCR. In addition also the mRNA expression profiles of the essential transcription factors STAT1alpha, IRF1 and C/EBPbeta were investigated. The data confirm a crucial role for STAT1alpha as well as for C/EBPbeta in the regulation of 1alpha-hydroxylase in monocytes.

IL-10- and IL-12-independent down-regulation of allergic sensitization by stimulation of CD40 signaling

Interaction between CD154 (CD40 ligand) on activated T lymphocytes and its receptor CD40 has been shown to be critically involved in the generation of cell-mediated as well as humoral immunity. CD40 triggering activates dendritic cells (DC), enhances their cytokine production, up-regulates the expression of costimulatory molecules, and induces their maturation. It is unknown how stimulation of CD40 during sensitization to an airborne allergen may affect the outcome of allergic airway inflammation. We took advantage of a mouse model of allergic asthma and a stimulatory mAb to CD40 (FGK45) to study the effects of CD40-mediated DC activation on sensitization to OVA and subsequent development of OVA-induced airway inflammation. Agonistic anti-CD40 mAb (FGK45) injected during sensitization with OVA abrogated the development of allergic airway inflammation upon repeated airway challenges with OVA. Inhibition of bronchial eosinophilia corresponded with reduced Th2 cytokine production and was independent of IL-12, as evidenced by a similar down-regulatory effect of anti-CD40 mAb in IL-12 p40-deficient mice. In addition, FGK45 equally down-regulated allergic airway inflammation in IL-10-deficient mice, indicating an IL-10-independent mechanism of action of FGK45. In conclusion, our results show that CD40 signaling during sensitization shifts the immune response away from Th2 cytokine production and suppresses allergic airway inflammation in an IL-12- and IL-10-independent way, presumably resulting from enhanced DC activation during sensitization.

Increased peritoneal and endometrial gene expression of biologically relevant cytokines and growth factors during the menstrual phase in women with endometriosis

OBJECTIVE

To examine differential messenger RNA (mRNA) expression of relevant cytokines, metalloproteases, growth and adhesion factors in endometrium and peritoneum from women with endometriosis when compared with women without the disease during menstrual and luteal phases of the cycle.

DESIGN

Patients with endometriosis were compared with control patients.

SETTING

University hospital.

PATIENT(S)

A total of 35 patients (20 patients during the luteal phase and 15 patients during the menstrual phase) were selected for this study on the basis of cycle phase and presence or absence of endometriosis.

INTERVENTION(S)

In this study, endometriosis was laparoscopically and histologically confirmed in 24 women with endometriosis of revised American Society for Reproductive Medicine (ASRM) stage I-II (n = 12) and revised ASRM stage III-IV (n = 12), and the presence of a normal pelvis was documented by laparoscopy in 11 control patients. The macroscopically normal peritoneum tissues were collected from lateral wall left or right, near the colon ascendens or descendens.

MAIN OUTCOME MEASURE(S)

The expression levels were determined as ratios between the target molecules and beta-actin as housekeeping gene.

RESULT(S)

In women with endometriosis, peritoneal mRNA levels of matrix metalloproteinase (MMP)-3, transforming growth factor-beta, interleukin (IL)-6, and intercellular adhesion molecule-1 and endometrial mRNA levels of MMP-3, tumor necrosis factor (TNF)-alpha, and IL-8 were significantly higher during the menstrual phase when compared with luteal phase. During the menstrual phase of the cycle, both endometrial expression of TNF-alpha, IL-8, and MMP-3 mRNA levels and peritoneal expression of transforming growth factor-beta, IL-6, and intercellular adhesion molecule-1 mRNA levels were significantly higher in women with endometriosis when compared with controls. Immunohistochemical staining confirmed the presence of TNF-alpha in peritoneum and endometrium in both women with endometriosis and controls.

CONCLUSION(S)

Increased endometrial and peritoneal cytokine mRNA expression during menstruation may contribute to a pelvic inflammatory microenvironment favoring the development of endometriosis.

CCL27 is a critical factor for the development of atopic dermatitis in the keratin-14 IL-4 transgenic mouse model

The keratin-14 IL-4 transgenic (Tg) mouse model of atopic dermatitis (AD) is characterized by skin infiltration of T cells, early up-regulation of T(h)2 cytokines and late surge of T(h)1 cytokines. In the present study, we investigated the role of CCL27, a T cell skin-homing chemokine known to be elevated in sera of human AD patients, in disease development in our animal model of AD. The results showed that the mRNA and protein levels of CCL27 in the skin and serum were significantly increased in IL-4 Tg mice. The percentage of T cells expressing CCR10 in skin draining lymph nodes of IL-4 Tg mice was increased, consistent with the findings of >80% of skin-infiltrating T cells in Tg mice expressing CCR10. Chemotaxis transmigration assay demonstrated that CCL27 promotes a greater degree of migration of T cells in diseased Tg mice. Subcutaneous injection of neutralizing anti-CCL27 to IL-4 Tg mice with early skin lesions resulted in reduced clinical progression of inflammation, accompanied with decreased T cell and mast cell infiltration in the skin, and down-regulation of inflammatory cytokines. In conclusion, CCL27 and CCR10 interaction is important for the development of skin inflammation in our AD model.

Stimulation of A2A-adenosine receptors after myocardial infarction suppresses inflammatory activation and attenuates contractile dysfunction in the remote left ventricle

Following myocardial infarction (MI), contractile dysfunction develops not only in the infarct zone but also in noninfarcted regions of the left ventricle remote from the infarct zone. Inflammatory activation secondary to MI stimulates inducible nitric oxide synthase (iNOS) induction with excess production of nitric oxide. We hypothesized that the anti-inflammatory effects of selective A2A-adenosine receptor (A2AAR) stimulation would suppress inflammation and preserve cardiac function in the remote zone early after MI. A total of 53 mice underwent 60 min of coronary occlusion followed by 24 h of reperfusion. The A2AAR agonist (ATL146e, 2.4 μg/kg) was administered intraperitoneally 1, 3, and 6 h postreperfusion. Because of the 1-h delay in treatment after MI, ATL146e had no effect on infarct size, as demonstrated by contrast-enhanced cardiac MRI ( n = 18) performed 24 h post-MI. ATL146e did however preserve global cardiac function at that time by limiting contractile dysfunction in remote regions [left ventricle wall thickening: 51 ± 4% in treated ( n = 9) vs. 29 ± 3% in nontreated groups ( n = 9), P < 0.01]. RT-PCR, immunohistochemistry, and Western blot analysis indicated that iNOS mRNA and protein expression were significantly reduced by ATL146e treatment in both infarcted and noninfarcted zones. Similarly, elevations in plasma nitrate-nitrite after MI were substantially blunted by ATL146e ( P < 0.01). Finally, treatment with ATL146e reduced NF-κB activation in the myocardium by over 50%, not only in the infarct zone but also in noninfarcted regions ( P < 0.05). In conclusion, A2AAR stimulation after MI suppresses inflammatory activation and preserves cardiac function, suggesting the potential utility of A2AAR agonists against acute heart failure in the immediate post-MI period.

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.

Evaluation of airway inflammation by quantitative Th1/Th2 cytokine mRNA measurement in sputum of asthma patients

BACKGROUND

Asthma is a chronic inflammatory disorder of the airways driven by T cell activation. Th2 cells and their cytokines are thought to play a role in the pathophysiology of allergic as well as non-allergic asthma.

METHODS

Airway cells were obtained by sputum induction from 15 healthy and 39 asthmatic individuals and the airway T cell cytokine profiles (interleukin (IL)-4, IL-5, IL-13, IL-10 and interferon (IFN)-gamma) at the mRNA level were studied by real time RT-PCR.

RESULTS

Asthma patients had increased expression of IL-5 (p = 0.001) and IL-13 (p = 0.03) mRNA in sputum compared with non-asthmatic controls. IL-4 mRNA and IFN-gamma mRNA were detectable in the sputum of 44% and 21% of patients, respectively, but not in controls. Sputum IL-10 mRNA levels did not differ significantly between patients and controls. Sputum mRNA expression levels of IL-4, IL-5, and IL-13 were significantly correlated with the percentage of eosinophils and were higher in subjects with allergic asthma than in those with non-allergic asthma (p = 0.03, p = 0.02 and p = 0.0002, respectively); they did not differ between mild asthmatic subjects and those with moderate to severe asthma. In contrast, IFN-gamma mRNA expression was higher in non-allergic than in allergic patients (p = 0.04) and higher in patients with moderate to severe asthma than in those with mild asthma (p<0.01). Sputum IL-5 mRNA levels (but not the other cytokine mRNA levels) were also correlated with exhaled nitric oxide (eNO) and with bronchial hyperreactivity expressed as the histamine concentration resulting in a 20% decrease in forced expiratory volume in 1 second.

CONCLUSION

Real time RT-PCR analysis of mRNA in induced sputum confirms a predominance of Th2 cytokines in both allergic and non-allergic asthma. IL-5 levels reflect eosinophil infiltration as well as eNO levels and hyperreactivity, and levels of the Th1 cytokine IFN-gamma indicate asthma severity. The technique is a promising tool for use in further studies of asthma severity and disease activity.

The disease progression in the keratin 14 IL-4-transgenic mouse model of atopic dermatitis parallels the up-regulation of B cell activation molecules, proliferation and surface and serum IgE

We have previously characterized the keratin 14 interleukin-4-transgenic (IL-4-Tg) mouse model of atopic dermatitis as a chronic pruritic inflammatory skin disease typified by skin infiltration of inflammatory cells and early up-regulation of Th2 cytokines and late surge of Th1 cytokines. In the present study, we examined the involvement of B cells. Systematic examinations of the following immunological parameters on B cells were carried out in non-Tg control mice and in IL-4-Tg mice at before disease onset and early and late disease stages so that we could determine the immunological sequence of events leading to the disease development: surface expressions of IA/IE, activation and costimulatory molecules, proliferation under LPS or IgM stimulation, quantification of cell surface and serum IgE, IgG1, and IgG2a. Our results showed that as the disease progresses from before onset to early disease and to late disease, there is a parallel increase in surface markers of B cell activation (IA/IE, CD44, CD69, CD80 and CD86), in B cell proliferation, and in cell surface and serum IgE. Significant increases of Th2-driven serum IgG1 and IgE in early disease was followed by significant increase of Th1-driven IgG2a in late disease. Importantly the significant increases of activation molecule (IA/IE), proliferation (to LPS), and surface IgE on B cells of the IL-4-Tg mice precedes the up-regulation of serum IgE and disease onset. These data suggest that activated B cells may play a role in atopic dermatitis disease development by up-regulating serum IgE concentration, which serves as a marker of disease onset.

Validation of real-time RT-PCR assays for mRNA quantification in baboons

Real-time RT-PCR has been used widely, both in fundamental research and in clinical diagnostics, for instance for quantification of RNA levels in human tissues and tissue biopsies. In the present study we provide a strategy to validate primers/probes for real-time RT-PCR quantification of baboon samples. The method is based on the TaqMan system and uses primers/probes that have been designed and validated for human real-time RT-PCR. A prerequisite for the accuracy of this strategy is a similar amplification efficiency between human and baboon PCR reactions. We propose two different methods, i.e. by calculating PCR efficiencies from the slope of a dilution curve or by using the linear regression method, to compare the amplification efficiency between human and baboon samples. In conclusion, by performing a simple validation experiment, real-time PCR assays based on human sequences, which are easily available, can be applied for analysis of baboon samples.

1α,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.

Vitamin D deficiency in early life accelerates Type 1 diabetes in non-obese diabetic mice

AIMS/HYPOTHESIS

1,25-dihydroxyvitamin D(3), the active form of vitamin D, prevents Type 1 diabetes in non-obese diabetic (NOD) mice. Epidemiological data show a threefold increase in human Type 1 diabetes when vitamin D deficiency was present in the first months of life. To evaluate whether a similar dietary deficiency affects diabetes incidence in NOD mice, we generated NOD mice with vitamin D deficiency in early life.

METHODS

Breeding pairs of NOD mice, as well as their offspring (test mice), were kept in surroundings devoid of ultraviolet light and were fed a vitamin D-depleted diet for 100 days. Mice were followed for 250 days.

RESULTS

At 250 days, 35% (12/35) male and 66% (22/33) female vitamin D-deficient mice were diabetic compared to 15% (6/40, p=0.05) and 45% (13/29, p<0.01) of the control mice. At 100 days no difference in insulitis was seen, but more vitamin D-deficient mice were glucose intolerant. Higher IL1 expression was detected in islets of vitamin D-deficient mice and their peritoneal macrophages had an aberrant cytokine profile (low IL1 and IL6, high IL15). Thymus and lymph nodes of vitamin D-deficient mice contained less CD4(+)CD62L(+) cells.

CONCLUSION/INTERPRETATION

Vitamin D status increases the expression of Type 1 diabetes in NOD mice. Our data in NOD mice, as well as human epidemiological data, point to the importance of preventing vitamin D deficiency in early childhood. Controlling this dietary factor could be an easy and safe way to reduce the incidence of Type 1 diabetes in subjects who are genetically at risk.

Hen egg white lysozyme vaccination induces acute shock in NOD mice

To investigate whether vaccination could induce lethal shock and which mechanisms are involved in this phenomenon, we tested a panel of autoantigens or diabetes-irrelevant peptides or proteins in nonobese diabetic (NOD), Balb/c, and C57Bl/6 mice. Of the antigens tested, only nondiabetogenic hen egg white lysozyme induced a severe form of shock exclusively in NOD mice. The mechanism involved is suggestive of a Th(2)-mediated anaphylactic reaction possibly connected to activation of PAF and triggering of DIC.

Prevention of primary non-function of islet xenografts in autoimmune diabetic NOD mice by anti-inflammatory agents

AIMS/HYPOTHESIS

High levels of inflammation locally in the graft during the initial days after transplantation can cause primary non-function (PNF) of grafted xenogeneic islets in NOD mice. The aim of this study was to explore in a model of spontaneous diabetes, the NOD mouse, the potential of anti-inflammatory agents in the prevention of PNF after xenogeneic islet transplantation.

METHODS

Spontaneously diabetic NOD mice were transplanted with 300 rat islets. Animals were treated with acetylsalicylic acid (AsA), rofecoxib, TGF-beta or IL-1 receptor antagonist (IL-1ra). Intra-graft expression of inflammation-related molecules was measured by real time PCR 8 h post-transplantation. At the same time point, plasma nitrite levels were measured.

RESULTS

Xenogeneic islets transplanted in control spontaneously diabetic mice resulted in PNF in 16 out of 38 mice (42%). Initial graft loss was not altered by administration of rofecoxib (30%) or TGF-beta (25%). AsA reduced the rate of rapid graft loss to 8% ( p<0.05 vs controls) and administration of IL-1ra even totally prevented PNF (0%, p<0.05 vs controls). Furthermore, all therapies prolonged the mean survival time of xenogeneic islet grafts. The inhibition of PNF by AsA was associated with decreased intra-islet levels of inflammation-related molecules (IL-1, TNF-alpha, iNOS, COX-2) and chemokines (MCP-1 and MIP-3alpha). Finally, also a diminished production of systemic nitrite levels was observed in AsA- and IL-1ra-treated islet recipients.

CONCLUSIONS/INTERPRETATION

These data show that treatment with AsA or IL-1ra prevents PNF after islet transplantation in spontaneously diabetic NOD mice. Moreover, the involvement of non-specific inflammation is recognized in xenogeneic islet PNF in spontaneously diabetic NOD mice.

Defect in activation-induced cell death in non-obese diabetic (NOD) T lymphocytes

Activation-induced cell death (AICD) represents a major means of peripheral tolerance induction, eliminating effector cells. NOD mice, a widely used model for autoimmune diabetes, are characterized by high levels of circulating T lymphocytes and by resistance to several apoptosis-inducing signals. The aim of this study was to analyse AICD in peripheral NOD T lymphocytes. First, we demonstrated in an in vitro AICD model that NOD T lymphocytes are more resistant to AICD (64+/-2%) compared to non-autoimmune C57BL/6 T lymphocytes (73+/-2%), but also diabetes-resistant NOR T lymphocytes (76+/-3%, P<0.05). Moreover, both CD4(+)and CD8(+)subsets were affected. Analysis of the cellular and molecular pathways revealed lower caspase 8 levels, a central caspase proximally involved in the AICD-pathway (fluorescence of 258+/-47 in NOD vs. 441+/-16 in NOR and 414+/-61 in C57BL/6 T lymphocytes, P<0.05). Gene expression analysis using real-time RT-PCR additionally revealed low expression of Fas and FasL, the death receptor system activating caspase 8 and contributing to AICD. Additionally, low IL-2 levels, together with high TGFbeta and Bclx-L levels, confirm the presence of a NOD-specific AICD-resistance profile. In conclusion, we present cellular and molecular evidence for disturbed AICD mechanisms in NOD T lymphocytes. This resistance in AICD may contribute to defective tolerance induction to autoantigens in NOD mice.

Combination of a 1,25-dihydroxyvitamin D3 analog and a bisphosphonate prevents experimental autoimmune encephalomyelitis and preserves bone

The vitamin D analog TX527 (19-nor-14,20-bis epi-23-yne-1,25(OH)(2)D(3)), decreased disease severity (P < 0.001) and postponed disease onset (P < 0.0001) in SJL mice in which experimental autoimmune encephalomyelitis was induced. Levels of IFN-gamma and IL-2 mRNA were decreased in spinal cord and spleen in the analog-treated mice, suggesting a Th(1)-targeted effect. Adding the bisphosphonate pamidronate did not affect analog-protective efficacy, but completely prevented TX527-caused acceleration of bone turnover and increased total bone mineral content as well as femoral mineral and calcium content (P < 0.01). Less calcemic analogs of 1,25-dihydroxyvitamin D(3), in combination with bone sparing products such as bisphosphonates allow immune modulation in vivo without affecting bone.

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.

Interleukin-17 orchestrates the granulocyte influx into airways after allergen inhalation in a mouse model of allergic asthma

Interleukin (IL)-17 is produced by activated memory CD4(+) cells and induces cytokines and chemokines that stimulate neutrophil generation and recruitment. Here, we investigated the involvement of IL-17 in the bronchial influx of neutrophils in experimental allergic asthma. Inhalation of nebulized ovalbumin (OVA) by sensitized mice with bronchial eosinophilic inflammation resulting from chronic OVA exposure induced early IL-17 mRNA expression in inflamed lung tissue, concomitant with a prominent bronchial neutrophilic influx. Anti-IL-17 monoclonal antibodies (mAb) injected before allergen inhalation strongly reduced bronchial neutrophilic influx, in a manner equally as potent as the anti-inflammatory dexamethasone. Remarkably, anti-IL-17 mAb significantly enhanced IL-5 levels in both BAL fluid and serum, and aggravated allergen-induced bronchial eosinophilia. In another series of experiments, anti-IL-17 mAb were given repeatedly during the inhalatory challenge phase with OVA of sensitized mice. This treatment regimen abated bronchial neutrophilia in parallel with reduction of bone marrow and blood neutrophilia. In addition, anti-IL-17 mAb treatment elevated eosinophil counts in the bone marrow and bronchial IL-5 production, without alteration of allergen-induced bronchial hyperresponsiveness. In summary, our results demonstrate that IL-17 expression in airways is upregulated upon allergen inhalation, and constitutes the link between allergen-induced T cell activation and neutrophilic influx. Because neutrophils may be important in airway remodeling in chronic severe asthma, targeting IL-17 may hold therapeutic potential in human asthma.

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.

Treatment of autoimmune diabetes recurrence in non-obese diabetic mice by mouse interferon-beta in combination with an analogue of 1alpha,25-dihydroxyvitamin-D3

Autoimmune diabetes recurrence is in part responsible for islet graft destruction in type 1 diabetic individuals. The aim of the present study was to design treatment modalities able to prevent autoimmune diabetes recurrence after islet transplantation in spontaneously diabetic NOD mice. In order to avoid confusion between autoimmune diabetes recurrence and allograft rejection, we performed syngeneic islet transplantations in spontaneously diabetic NOD mice. Mice were treated with mouse interferon-beta (IFN-beta, 1 x 105 IU/day), a new 14-epi-1,25-(OH)2D3-analogue (TX 527, 5 microg/kg/day) and cyclosporin A (CsA, 7.5 mg/kg/day) as single substances and in combinations. Treatment was stopped either 20 days (IFN-beta and CsA) or 30 days (TX 527) after transplantation. Autoimmune diabetes recurred in 100% of control mice (MST 11 days). None of the mono-therapies significantly prolonged islet graft survival. Combining CsA with TX 527 maintained graft function in 67% of recipients as long as treatment was given (MST 31 days, P < 0.01 versus controls). Interestingly, 100% of the IFN-beta plus TX 527-treated mice had normal blood glucose levels during treatment, and even had a more pronounced prolongation of graft survival (MST 62 days, P < 0.005 versus controls). Cytokine mRNA analysis of the grafts 6 days after transplantation revealed a significant decrease in IL-2, IFN-gamma and IL-12 messages in both IFN-beta plus TX 527- and CsA plus TX 527-treated mice, while only in the IFN-beta with TX 527 group were higher levels of IL-10 transcripts observed. Therefore, we conclude that a combination of IFN-beta and TX 527 delays autoimmune diabetes recurrence in islet grafts in spontaneously diabetic NOD mice.

Blockade of CTLA-4 enhances allergic sensitization and eosinophilic airway inflammation in genetically predisposed mice

CTLA-4 (CD152) expression is restricted to subsets of activated T lymphocytes and shares homology with CD28. CTLA-4 and CD28 molecules both bind to B7 molecules on antigen-presenting cells. Whereas CD28-B7 interaction enhances T cell activation, cytokine production and survival, CTLA-4 signaling down-regulates T cell responses. Here, we studied the involvement of CTLA-4 triggering in the pathogenesis of allergen-induced airway inflammation in mice. Anti-CTLA-4 mAb were injected during i.p. sensitization with ovalbumin (OVA). This treatment favored OVA-specific IgE production and augmented blood eosinophilia in BALB/c mice. In BALB/c mice, enhanced Th2 sensitization after anti-CTLA-4 mAb injections resulted in more severe airway inflammation, and increased airway hyperresponsiveness to metacholine, bronchial eosinophilia and IL-4 and IL-5 levels in broncho-alveolar lavage (BAL) fluid following repeated allergen inhalations. Importantly, aggravation of airway inflammation and enhancement of Th2 responses were accompanied by a significant reduction of pulmonary TGF-beta levels at protein level in BAL fluid as well as on mRNA level in inflamed lung tissue. In contrast to BALB/c mice, blockade of CTLA-4 did not alter IgE production nor the phenotype of airway inflammation or TGF-beta production in C57BL/6 mice. Our data suggest that CTLA-4 triggering represents an important regulatory mechanism for Th2 sensitization in genetically predisposed mice by modulating TGF-beta production.

An overview of real-time quantitative PCR: applications to quantify cytokine gene expression

The analysis of cytokine profiles helps to clarify functional properties of immune cells, both for research and for clinical diagnosis. The real-time reverse transcription polymerase chain reaction (RT-PCR) is becoming widely used to quantify cytokines from cells, body fluids, tissues, or tissue biopsies. Being a very powerful and sensitive method it can be used to quantify mRNA expression levels of cytokines, which are often very low in the tissues under investigation. The method allows for the direct detection of PCR product during the exponential phase of the reaction, combining amplification and detection in one single step. In this review we discuss the principle of real-time RT-PCR, the different methodologies and chemistries available, the assets, and some of the pitfalls. With the TaqMan chemistry and the 7700 Sequence Detection System (Applied Biosystems), validation for a large panel of murine and human cytokines and other factors playing a role in the immune system is discussed in detail. In summary, the real-time RT-PCR technique is very accurate and sensitive, allows a high throughput, and can be performed on very small samples; therefore it is the method of choice for quantification of cytokine profiles in immune cells or inflamed tissues.

Role of interleukin-12 in the induction of mucosal inflammation and abrogation of regulatory T cell function in chronic experimental colitis

IL-12 promotes Th1 cell differentiation and cell-mediated immunity. In the present study, the potential role of IL-12 was analyzed in an experimental colitis model in scid mice reconstituted with syngeneic CD45RBhighCD4+ T cells. Real-time reverse transcription-PCR studies demonstrated that IL-12 p40 mRNA in inflamed colon is induced shortly after T cell transfer and maintained at a stable level after week 4, at the time when wasting disease starts. Administration of anti-IL-12 on days 0,14, and 28 (early treatment) or on days 28, 42, and 56 (delayed treatment) after T cell transfer, effectively prevented or, respectively cured wasting disease and colitis in scid recipients. Anti-IL-12 treatment abrogated mucosal inflammation with significantly diminished leukocyte infiltration (CD4 cells, macrophages) and CD54 expression, and down-regulated proinflammatory cytokines IFN-gamma and IL-2. Of note, although splenic CD4+ T cells are unable to induce disease as a result of the presence of regulatory CD45RBlow cells, splenic CD4+ T cells, preactivated by IL-12 and anti-CD3 in vitro, were highly pathogenic in inducing severe mucosal inflammation, suggesting that IL-12 and anti-CD3 abrogated regulatory T cell function. These findings indicate that IL-12 is important for the induction of experimental colitis through effects on proinflammatory cytokine production and on regulatory T cell function.

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.