Differential expression of CC chemokines and the CCR5 receptor in the pancreas is associated with progression to type I diabetes

Islet expression of M3 uncovers a key role for chemokines in the development and recruitment of diabetogenic cells in NOD mice

OBJECTIVE

Type 1 diabetes is an autoimmune disease characterized by a local inflammatory reaction in and around islets followed by selective destruction of insulin-secreting beta-cells. We tested the hypothesis that chemokines affect different mechanisms responsible for the development of diabetes in NOD mice.

RESEARCH DESIGN AND METHODS

We examined chemokine expression in islets of NOD mice and tested their functional relevance to development of diabetes using transgenic mice expressing the mouse herpesvirus 68-encoded chemokine decoy receptor M3 (NOD-M3 mice) in insulin-secreting beta-cells.

RESULTS

Multiple chemokines were expressed in pancreatic islets of NOD mice before development of diabetes. Islet-specific expression of the pan-chemokine inhibitor M3 dramatically reduced leukocyte infiltration and islet destruction and completely blocked development of diabetes in NOD-M3 mice. M3 blocked diabetes by inhibiting the priming of diabetogenic cells in the pancreatic lymph nodes and their recruitment into the islets. This effect was specific to the pancreatic islets because M3 expression did not affect other ongoing autoimmune processes.

CONCLUSIONS

These results demonstrate that chemokines mediate afferent and efferent immunity in type 1 diabetes and suggest that broad chemokine blockade may represent a viable strategy to prevent insulitis and islet destruction.

Induction of monocyte chemoattractant protein-1 expression by angiotensin II in the pancreatic islets and beta-cells

Angiotensin II (AngII), the principal hormone of the renin-angiotensin system, is actively generated in the pancreas and has been suggested as a key mediator of inflammation. Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that plays an important role in the recruitment of mononuclear cells into the pancreatic islets. In this study, we investigated the potential molecular basis for the role of AngII in islet inflammation through studying its effect on MCP-1. AngII significantly increased the expression of MCP-1 mRNA and protein in the RINm5F beta-cell line and activated MCP-1 promoter. AngII-MCP-1 mRNA induction was inhibited by an AngII type 1 receptor antagonist but was unchanged by an AngII type 2 receptor antagonist. AngII-MCP-1 induction was inhibited by the tyrosine kinase inhibitor genistein, suggesting a MAPK signaling mechanism. AngII activated the phosphorylation of ERK1/2 but not p38 or c-Jun NH(2)-terminal MAPKs. Inhibition of ERK1/2 activation reduced the AngII-induced MCP-1 synthesis. In nonobese diabetic mice pancreata, the temporal pattern of angiotensin-converting enzyme expression correlated well with progression of insulitis and beta-cell destruction. Immunostaining of pancreatic serial sections show colocalization of angiotensin-converting enzyme with MCP-1 in beta-cells in the islets. In freshly isolated islets from normoglycemic mice, AngII alone and in combination with IL-1beta elicited an inflammatory response by stimulation of MCP-1. Our data suggest a positive autocrine/paracrine action for the local pancreatic AngII-generating system during insulitis and provide the first insight into an AngII-initiated signal transduction pathway that regulates MCP-1 as a possible inflammatory mechanism in the islets.

Quantification of chemokines by real-time reverse transcriptase PCR: applications in type 1 diabetes

Type 1 diabetes is a T-cell mediated autoimmune disease, characterized by the destruction of insulin-producing pancreatic beta-cells. This review will discuss the role of chemokines in the recruitment of immune cells leading to the pathology of this disease. There will be a focus on the quantification of chemokines and chemokine receptors by the recently developed real-time reverse transcriptase PCR technique. Today, this technique is in widespread use for analysis of chemokines in cells, tissues and tissue biopsies. The minute amount of tissue needed for analysis, as well as the very high sensitivity of this method, make it the method of choice for analysis of chemokines, which are often expressed at very low levels in target tissues. However, validation and optimization of the technique is of crucial importance for obtaining reliable results.

Adenosine receptor activation ameliorates type 1 diabetes

Growing evidence indicates that adenosine receptors could be promising therapeutic targets in autoimmune diseases. Here we studied the role of adenosine receptors in controlling the course of type 1 diabetes. Diabetes in CD-1 mice was induced by multiple-low-dose-streptozotocin (MLDS) treatment and in nonobese diabetic (NOD) mice by cyclophosphamide injection. The nonselective adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) prevented diabetes development in both MLDS-challenged mice and in cyclophosphamide-treated NOD mice. The effect of NECA was reversed by the selective A2B receptor antagonist N-(4-cyanophenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)phenoxy]acetamide (MRS 1754). The selective A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA) and A3 receptor agonist N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) were less efficacious in ameliorating the course of diabetes. NECA inhibited diabetes in A2A receptor KO mice and the selective A2A receptor agonist 2-p-(2-carboxyethyl)phenethyl-amino-5'-N-ethyl-carboxamidoadenosine (CGS21680) had no effect in normal mice, indicating a lack of role of A2A receptors. NECA failed to prevent cytokine-induced beta-cell death in vitro, but NECA strongly suppressed expression of the proinflammatory cytokines TNF-alpha, MIP-1alpha, IL-12, and IFN-gamma in pancreata, endotoxin, or anti-CD3-stimulated splenic cells, and T helper 1 lymphocytes, indicating that the beneficial effect of NECA was due to immunomodulation. These results demonstrate that adenosine receptor ligands are potential candidates for the treatment of type 1 diabetes.

The Chemokine Binding Protein M3 Prevents Diabetes Induced by Multiple Low Doses of Streptozotocin

Multiple injections of low-dose streptozotocin (MLDS) induce lymphocytic insulitis and diabetes in rodents. To test whether the influx of inflammatory cells was associated with changes in the expression of chemokines, we measured the expression of all known chemokine ligands by real-time quantitative PCR in isolated islets. With the exception of CCL20 and CCL19, chemokines were not significantly expressed in islets from wild-type mice before MLDS treatment. Ten days after treatment, the expression of several chemokines, including CXCL9, CCL1, CXCL10, and CCL21, was dramatically up-regulated. The expression of CCL1, CXCL9, and CCL21 protein was confirmed by immunohistochemistry and was mostly associated with the infiltrating cells. The mouse herpesvirus 68-encoded chemokine decoy receptor M3 can broadly engage these chemokines with high affinity. To test whether a blockade of chemokine function would alter the onset or magnitude of insulitis and diabetes, we used transgenic mice expressing M3 in beta cells (rat insulin promoter (RIP)-M3 mice). RIP-M3 mice were normoglycemic and responded normally to glucose challenge but were remarkably resistant to diabetes induced by MLDS. Islets from MLDS-treated RIP-M3 mice had fewer inflammatory cells and expressed lower levels of chemokines than those from MLDS-treated controls. The role of M3 in chemokine blockade during insulitis was further supported by in vitro experiments demonstrating that multiple chemokines up-regulated during islet inflammation are high-affinity M3 ligands that can be simultaneously sequestered. These results implicate chemokines as key mediators of insulitis and suggest that their blockade may represent a novel strategy to prevent insulitis and islet destruction.

CCL4 protects from type 1 diabetes by altering islet beta-cell-targeted inflammatory responses

We previously reported that interleukin (IL)-4 treatment of nonobese diabetic (NOD) mice elevates intrapancreatic CCL4 expression and protects from type 1 diabetes. Here, we show that antibody neutralization of CCL4 abrogates the ability of T-cells from IL-4-treated NOD mice to transfer protection against type 1 diabetes. Intradermal delivery of CCL4 via a plasmid vector stabilized by incorporation of the Epstein-Barr virus EBNA1/oriP episomal maintenance replicon (pHERO8100-CCL4) to NOD mice beginning at later stages of disease progression protects against type 1 diabetes. This protection was associated with a Th2-like response in the spleen and pancreas; decreased recruitment of activated CD8(+) T-cells to islets, accompanied by diminished CCR5 expression on CD8(+) T-cells; and regulatory T-cell activity in the draining pancreatic lymph nodes. Thus, inflammatory responses that target islet beta-cells are suppressed by CCL4, which implicates the use of CCL4 therapeutically to prevent type 1 diabetes.

Alloantigen-enhanced accumulation of CCR5+ 'effector' regulatory T cells in the gravid uterus

Regulatory T cells play an essential role in preventing fetal rejection by the maternal immune system. Here we show that, based on the expression of CCR5, regulatory T cells can be divided into a highly suppressive CCR5+ and a far less suppressive CCR5- subpopulation, suggesting that the former represent the effector arm of regulatory T cells. Although regulatory T cells from CCR5-/- gene deletion mutants still suppress, they are less effective mediators of maternal-fetal tolerance. The accumulation of CCR5+ regulatory T cells at this site appears to be enhanced by alloantigen. This finding is in stark contrast to the systemic expansion of regulatory T cells during pregnancy, which appears to be alloantigen-independent. The fact that CCR5+ regulatory T cells preferentially accumulate in the gravid uterus and that expression of CCR5 on regulatory T cells can be induced by activation lead us to propose that CCR5 is responsible for the accumulation of those regulatory T cells that have been activated by paternal antigens.

The chemokine decoy receptor M3 blocks CC chemokine ligand 2 and CXC chemokine ligand 13 function in vivo

Chemokines and their receptors play a key role in immune homeostasis regulating leukocyte migration, differentiation, and function. Viruses have acquired and optimized molecules that interact with the chemokine system. These virus-encoded molecules promote cell entry, facilitate dissemination of infected cells, and enable the virus to evade the immune response. One such molecule in the murine gammaherpesvirus 68 genome is the M3 gene, which encodes a secreted 44-kDa protein that binds with high affinity to certain murine and human chemokines and blocks chemokine signaling in vitro. To test the hypothesis that M3 directly interferes with diverse chemokines in vivo, we examined the interaction of M3 with CCL2 and CXCL13 expressed in the pancreas of transgenic mice. CCL2 expression in the pancreas promoted recruitment of monocytes and dendritic cells; CXCL13 promoted recruitment of B and T lymphocytes. Coexpression of M3 in the pancreas blocked cellular recruitment induced by both CCL2 and CXCL13. These results define M3 as multichemokine blocker and demonstrate its use as a powerful tool to analyze chemokine biology.

Salmonella typhimurium infection in nonobese diabetic mice generates immunomodulatory dendritic cells able to prevent type 1 diabetes

Infection, commencing across a wide age range, with a live, attenuated strain of Salmonella typhimurium, will halt the development of type 1 diabetes in the NOD mouse. The protective mechanism appears to involve the regulation of autoreactive T cells in a manner associated with long lasting changes in the innate immune compartment of these mice. We show in this study that autoreactive T cell priming and trafficking are altered in mice that have been infected previously by S. typhimurium. These changes are associated with sustained alterations in patterns of chemokine expression. We find that small numbers of dendritic cells from mice that have been previously infected with, but cleared all trace of a S. typhimurium infection are able to prevent the development of diabetes in the highly synchronized and aggressive cyclophosphamide-induced model. The effects we observe on autoreactive T cell trafficking are recapitulated by the immunomodulatory dendritic cell transfers in the cyclophosphamide model.

Immunohistochemical study of monocyte chemoattractant protein-1 in the pancreas of NOD mice following cyclophosphamide administration and during spontaneous diabetes

In type 1 diabetes mellitus (T1DM), the processes which control the recruitment of immune cells into pancreatic islets are poorly defined. Complex interactions involving adhesion molecules, chemokines and chemokine receptors may facilitate this process. The chemokine, monocyte chemoattractant protein-1 (MCP-1), previously shown to be important in leukocyte trafficking in other disease systems, may be a key participant in the early influx of blood-borne immune cells into islets during T1DM. In the non-obese diabetic (NOD) mouse, the expression of MCP-1 protein has not been demonstrated. We employed dual-label immunohistochemistry to examine the intra-islet expression, distribution and cellular source of MCP-1 in the NOD mouse following cyclophosphamide administration. NOD mice were treated with cyclophosphamide at day 72-73 and MCP-1 expression studied at days 0, 4, 7, 11 and 14 after treatment and comparisons were made between age-matched NOD mice treated with diluent and non-diabetes-prone CD-1 mice. Pancreatic expression of MCP-1 was also examined in NOD mice at various stages of spontaneous diabetes. In the cyclophosphamide group at day 0, MCP-1 immunolabelling was present in selective peri-islet macrophages but declined at day 4. It increased slightly at day 7 but was more marked from day 11, irrespective of diabetes development. The pattern of MCP-1 expression in macrophages was different over time in both the cyclophosphamide and control groups. In the cyclophosphamide group, there was a change over time with an increase at day 11. In the control group, there was little evidence of change over time. There was no significant difference in the mean percentage of MCP-1 positive macrophages between the cyclophosphamide-treated diabetic and non-diabetic mice. During spontaneous diabetes in the NOD mouse, only a few peri-islet MCP-1 cells appeared at day 45. These became more numerous from day 65 but were absent at diabetes onset. We speculate that a proportion of early islet-infiltrating macrophages which express MCP-1 may attract additional lymphocytes and macrophages into the early inflamed islets and intensify the process of insulitis.

The autoimmune diabetes locus Idd9 regulates development of type 1 diabetes by affecting the homing of islet-specific T cells

Several genetic insulin-dependent diabetes (Idd) intervals that confer resistance to autoimmune diabetes have been identified in mice and humans, but the mechanisms by which they protect against development of diabetes have not been elucidated. To determine the effect of Idd9 on the function of islet-specific T cells, we established novel BDC-Idd9 mice that harbor BDC2.5 TCR transgenic T cells containing the Idd9 of diabetes-resistant B10 mice. We show that the development and functional responses of islet-specific T cells from BDC-Idd9 mice are not defective compared with those from BDC mice, which contain the Idd9 of diabetes-susceptible NOD mice. Upon transfer, BDC T cells rapidly induced severe insulitis and diabetes in NOD.scid mice, whereas those from BDC-Idd9 mice mediated a milder insulitis and induced diabetes with a significantly delayed onset. BDC and BDC-Idd9 T cells expanded comparably in recipient mice. However, BDC-Idd9 T cells accumulated in splenic periarteriolar lymphatic sheaths, whereas BDC T cells were mainly found in pancreatic lymph nodes and pancreata of recipients, indicating that the transferred T cells differed in their homing. We provide evidence that the migration pattern of transferred BDC and BDC-Idd9 T cells at least partly depends on their differential chemotaxis toward the CCR7 ligand CCL19. Taken together, our data show that the Idd9 locus regulates development of type 1 diabetes by affecting the homing of islet-specific T cells.

Induction of tolerance in type 1 diabetes via both CD4+CD25+ T regulatory cells and T regulatory type 1 cells

Success in developing novel therapies to recommence self-tolerance in autoimmunity depends on the induction of T regulatory (Tr) cells. Here, we report that rapamycin combined with interleukin (IL)-10 efficiently blocks type 1 diabetes development and induces long-term immunotolerance in the absence of chronic immunosuppression in nonobese diabetic (NOD) mice. Rapamycin mediates accumulation in the pancreas of suppressive CD4(+)CD25(+)FoxP3(+) Tr cells, which prevent diabetes. IL-10 induces Tr type 1 (Tr1) cells, which reside in the spleen and prevent migration of diabetogenic T-cells to the draining lymph nodes. These two Tr cell subsets act in concert to control diabetogenic T-cells that are still present in long-term tolerant mice. Rapamycin plus IL-10 treatment, promoting distinct subsets of Tr cells, may constitute a novel and potent tolerance-inducing protocol for immune-mediated diseases.

Altered chemokine levels in individuals at risk of Type 1 diabetes mellitus

AIMS

The hypothesis was tested in an exploratory study that individuals at high risk of developing Type 1 diabetes mellitus have altered systemic levels of cytokines and chemokines.

SUBJECTS AND METHODS

Forty-two non-diabetic first-degree relatives of patients with Type 1 diabetes mellitus were recruited. Of these, 18 had multiple islet autoantibodies (islet cell antibody, glutamic acid decarboxylase antibody, IA-2 antibody). Follow-up for 9-11 years confirmed high vs. moderate diabetes risk in islet autoantibody-positive vs. -negative relatives. Cytokines and chemokines were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Serum concentrations of classic Th1-associated cytokines (IFN-gamma, IL-12, IL-18) or Th2/Treg-associated cytokines (IL-5, IL-10, IL-13) did not significantly differ in high vs. moderate diabetes risk group. However, of six chemokines analysed, levels of CCL3 and CCL4 were increased (P = 0.0442 and P = 0.0334) while CCL2 was decreased (P = 0.0318) in the multiple islet autoantibody-positive group. No significant differences were seen for CCL5, CCL11, CXCL10. There was a significant correlation between the two closely related chemokines CCL3 and CCL4 in individuals at risk (r = 0.84, P = 0.00005), but not in the autoantibody-negative group.

CONCLUSION

Relatives at high risk of developing Type 1 diabetes mellitus have abnormal cellular immune regulation at the level of systemic chemokines. The up-regulation of CCL3 and CCL4 vs. down-regulation of CCL2 suggests opposed functions of these chemokines in the disease process. These findings need to be confirmed by independent studies.

Effector function of diabetogenic CD4 Th1 T cell clones: a central role for TNF-alpha

Effector function of T cells in autoimmune diabetes has been widely studied with mixed populations of lymphoid T cells stimulated ex vivo, but this approach does not permit evaluation of the contribution by a single T cell clone in the inflammatory site during pathogenesis. We have investigated cytokine production both in vitro and in vivo in a panel of diabetogenic CD4 Th1 T cell clones derived from the NOD mouse. SuperArray analysis showed a common pattern of mRNA expression for inflammatory cytokines and receptors in vitro after TCR stimulation. Ex vivo intracellular cytokine staining demonstrated that two important inflammatory cytokines, IFN-gamma and TNF-alpha, were being made by these T cells recovered from the pancreas 6 days following adoptive transfer. TNF-alpha produced in the pancreas by pathogenic T cell clones and recruited macrophages was not the membrane-bound form. Secreted TNF-alpha can lead to production of multiple inflammatory chemokines, as were observed in the pathogenic clones by intracellular cytokine staining. Our results not only define the nature of an inflammatory cytokine response critical to development of diabetes, but also suggest its role in the regulation of other events during pathogenesis induced by CD4 T cells. Similar analyses in other models demonstrated that disease induced by CD4 T cell clones closely resembles spontaneous autoimmune diabetes in which both CD4 and CD8 T cells are required. Thus, cloned T cells in effect amplify effector function of T cells which otherwise may be difficult to detect without ex vivo stimulation.

Chemokines and their receptors: roles in specific clinical conditions and measurement in the clinical laboratory

Considerable progress has been achieved in our knowledge of the function of the chemokine system and in understanding its role in the pathophysiology of human diseases. This complex system, presently including approximately 50 cytokines and 20 receptors, coordinates leukocyte recruitment in a variety of human diseases, ranging from infectious and inflammatory diseases to cancer. A large body of literature has been published describing various assays for the measurement of chemokines in biologic fluids and tissues. We review information available on the role of chemokines in selected human diseases and provide examples of clinical situations in which chemokine determination might be of practical value, and we describe the currently available assays for their measurement.

Evidence for an enhanced adhesion of DC to fibronectin and a role of CCL19 and CCL21 in the accumulation of DC around the pre-diabetic islets in NOD mice

The non-obese diabetic (NOD) mouse is a widely used animal model for the study of human diabetes. The lymphocytic (peri-)insulitis is preceded by an early accumulation of dendritic cells (DC) around the islets of Langerhans. This DC accumulation is thought to derive from an influx of monocytes attracted by pro-inflammatory chemokines. Besides chemokines, extracellular matrix (ECM) proteins play an important role in the accumulation of leukocytes in tissues. We studied the expression of the chemokines CCL2, CCL5, CXCL10, CCL19 and CCL21 over time in pancreases of NOD and control mice by ELISA on pancreas lysates as well as by immunohistochemistry. In addition, we studied the adhesive capacity of bone marrow-derived DC (BMDC) to ECM components. DC in the NOD pancreas accumulated at sites with an intense expression of fibronectin. In vitro, NOD BMDC showed increased fibronectin adhesion and increased VLA-5 expression. At the time of early DC accumulation (<10 wk), the lymphoid tissue-related chemokines CCL19 and CCL21 were increased. Our findings support the view that the early accumulation of DC around the NOD islets is not the consequence of an enhanced attraction of precursors and immature DC by pro-inflammatory chemokines. It rather might be the consequence of an aberrantly enhanced adhesion and retention of NOD DC.

The clinical potential of chemokine receptor antagonists

Chemokines belong to a family of chemotactic cytokines that direct the migration of immune cells towards sites of inflammation. They mediate their biological effects by binding to cell surface receptors, which belong to the G protein-coupled receptor superfamily. Since chemokines and their receptors have been implicated in the pathophysiology of a number of autoinflammatory diseases, chemokine receptor antagonists could prove to be useful therapeutics to target these diseases. Here, we review the role of chemokines in autoimmunity, concentrating mainly on the chemokine receptors CCR1 and CCR5, and discuss the potential utility of antagonists that target these 2 receptors as they progress through the clinic.

Expression of the NK-1 receptor on islet cells and invading immune cells in the non-obese diabetic mouse

The underlying mechanistic causes of immune cell infiltration in the islets of Langerhans and beta cell failure in the non-obese diabetic (NOD) mouse is still to be completely revealed. Substance P (SP) is a substance known to have pro-inflammatory, endocrine, neuromodulatory and trophic effects, and its preferred receptor, the neurokinin receptor 1 (NK-1 R), is reported to be involved in extravasation of granulocytes and in inflammation and tissue derangement. Therefore, we have investigated the expression of NK-1 R during development of insulitis in the NOD mouse. We show that the magnitude of immunoreactivity scoring NK-1 R expression in the islets was increased in the 12-week-old NOD mouse. Expression of NK-1 R co-localized with expression of glucagon. In line with this expression pattern, we did not detect any effect of SP on glucose-induced insulin release. NK-1 R expression was particularly observed in islet cells in association with the clusters of immune cells. Expression of NK-1 R was also demonstrated in a fraction of the infiltrating B and T lymphocytes, as well as on infiltrating macrophages and dendritic cells. The observations show that the level of NK-1 R expression is increased in 12-week-old NOD mice, being correlated with the occurrence of islet mononuclear infiltration. Our data suggest that SP may act as a chemoattractant, contributing to the pathogenic mononuclear infiltration process in the NOD mouse. On the whole, the observations suggest that SP and the NK-1 R to certain extents are involved in the changes that occur during the development of insulitis in the NOD mouse.

Dendritic cells and macrophages are essential for the retention of lymphocytes in (peri)-insulitis of the nonobese diabetic mouse: a phagocyte depletion study

Dendritic cells (DC) and macrophages (Mphi) are present in high numbers in the pancreas of the non-obese diabetic (NOD) mouse during the diabetogenic process from very early stages onwards. In this study, we used clodronate-loaded liposomes to mediate the temporary systemic depletion of these phagocytic cells and monocytic precursors in order to modulate the pancreatic inflammation. Two intraperitoneal injections given with a 2-day interval to 8-week-old NOD mice depleted monocytes from the circulation and monocytes, DC and Mphi from the spleen within the first days after the injections. Monocytes, DC and Mphi reappeared in the circulation and the spleen within one week and had an unchanged phenotype and antigen presenting function. Interestingly, this treatment caused a delayed disappearance (7-21 days postinjection) of DC and Mphi from the endocrine pancreas at a time when monocytes, DC and Mphi had already repopulated the circulation and the spleen. The depletion of DC and Mphi from the endocrine pancreas was accompanied by a total disappearance of lymphocytes from the pancreas. DC, Mphi and lymphocytes reappeared in the pancreatic inflammatory infiltrates in treated mice from 28 days postdepletion onwards. Importantly, the treatment significantly postponed the onset of diabetes, leading to a strongly decreased incidence by 35 weeks of age. Taken together, our data show an essential role of phagocytic cells, that is, DC and Mphi, in the recruitment of lymphocytes to the pancreatic islets in NOD mice.

G-CSF treatment prevents cyclophosphamide acceleration of autoimmune diabetes in the NOD mouse

Cyclophosphamide (CY) accelerates autoimmune diabetes in the NOD mouse at different levels, including critical targeting of a regulatory T cell subset, exacerbation of pro-Th1 IFN-gamma production and promotion of inflammation in pancreatic islets. Here we evaluated the ability of G-CSF to antagonize the acceleration of the disease induced by CY. Human recombinant G-CSF, administered daily at 200 microg/kg by s.c. injection, protected NOD mice from CY-accelerated onset of glycosuria and insulitis. G-CSF accelerated the recovery of the T cell compartment after the depletion of the lymphoid compartment triggered by CY injection. It selectively prevented the loss of the immunoregulatory T cells expressing the CD4(+)CD25+ phenotype that also stained CD62L+ in peripancreatic lymph nodes and promoted their expansion in the spleen. In addition to this, it abrogated the robust cytokine--particularly IFN-gamma- and chemokine burst triggered in immune cells by CY. G-CSF promoted only slight changes in the inflammatory effects of CY at the target tissue site, assessed by chemokine induction within the pancreas. Thus the immunoregulatory properties of G-CSF were critical in the early control of the accelerating effects of CY on autoimmune diabetes in the NOD mouse.

Somatostatin receptors and autoimmune-mediated diabetes

Somatostatin (SST) peptide is produced by various SST-secreting cells throughout the body and acts as a neurotransmitter or paracrine/autocrine regulator in response to ions, nutrients, peptides hormones and neurotransmitters. SST is also widely distributed in the periphery to regulate the inflammatory and immune cells in response to hormones, growth factors, cytokines and other secretive molecules. SST peptides are considered the most important physiologic regulator of the islet cell, gastrointestinal cell and immune cell functions, and the importance of SST production levels has been implicated in several diseases including diabetes. The expression of SST receptors has also been found in T lymphocytes and primary immunologic organs. Interaction of SST and its receptors is also involved in T-cell proliferation and thymocyte selection. SSTR gene-ablated mice developed diabetes with morphologic, physiologic and immunologic alterations in the endocrine pancreas. Increased levels of mononuclear cell infiltration of the islets are associated with the increased levels of antigen-presenting cells located in the islets and peripancreatic lymph nodes. Increased levels of SST were also found in antigen-presenting cells and are associated with a significant increase of CD8 expression levels on CD4(+)/CD8(+) immature thymocytes. These findings highlight the crucial role of this neuroendocrine peptide and its receptors in regulating autoimmune functions.

Homing of human autoreactive T cells into pancreatic tissue of NOD-scid mice

AIMS/HYPOTHESIS

An important prerequisite for the initiation of pancreatic islet inflammation is the recruitment of pathogenic T cells. We investigated the in vivo migration patterns of human islet-reactive T cell clones after transfer into compromised hosts.

METHODS

NOD-scid mice were injected with a mixture of human autoreactive T cells and antigen-presenting cells. Survival and migration of T cells was analysed by fluorescence-activated cell sorter and immunohistochemical analysis of various tissues.

RESULTS

Autoreactive T cells and antigen-presenting cells survived at least 14 days in vivo and accumulated in spleen, pancreatic tissue and pancreas draining lymph nodes, but not elsewhere, as early as 4 days after transfer. This homing was dependent on co-injection of human antigen-presenting cells loaded with autoantigen. Finally, we found that this process is enhanced by streptozotocin treatment. Streptozotocin treatment did not affect the constitutive homing to pancreas draining lymph nodes. Histological analysis of pancreatic tissue sections showed some autoreactive T cells around the islets of Langerhans, comparable to early peri-islet insulitis. However, the majority of pancreas-infiltrating T cells accumulated around blood vessels in the exocrine pancreas. All T cell clones expressed the chemokine receptor CXCR3 that is associated with homing to insulitic lesions in men and mice.

CONCLUSIONS/INTERPRETATION

Our study provides the first evidence of in vivo accumulation in pancreatic tissue of islet-reactive T cells derived from type 1 diabetic patients. The fact that such T cells do not penetrate islets is in line with the concept that additional factors may be required for the entry of T cells into inflamed islets to become diabetogenic.

Polymorphisms of chemokine and chemokine receptor genes in Type 1 diabetes mellitus and its complications

Cytokines and chemokines have been implicated in the pathogenesis of Type 1 diabetes mellitus (T1DM) and its microvascular complications. Recently, genetic variants of monocyte chemotactic protein-1 (MCP-1), CC-chemokine receptor 2 (CCR2), CC-chemokine receptor 5 (CCR5) genes have been identified. The aim was to investigate whether genetic variants of the MCP-1 G(-2518)A, CCR2B 64I, CCR5 G(59029)A, and CCR5 Delta32 are associated with T1DM and its microvascular complications. Two hundred and sixty patients with T1DM with and without diabetic microvascular complications, and 104 normal controls were recruited for this study. Genotypes of the MCP-1 G(-2518)A, CCR2B 64I, CCR5 G(59029)A, and CCR5 delta32 were performed by polymerase chain reaction followed by digestion with appropriate restriction endonucleases. Frequencies of the MCP-1 A(-2518) allele (74.6% vs. 63.5%, p < 0.003) and A/A genotype (54.5% vs. 34.6%, p < 0.001, Pc = 0.002) were significantly higher in patients with T1DM compared with normal controls. CCR5 G(59029) was slightly increased in the patients with microvascular complications compared with the uncomplicated (21.4% vs. 10%, p < 0.03, Pc = ns). The frequency of haplotype G/G/W was slightly increased in the patients with diabetic complications compared to the uncomplicated (39.6% vs. 28.8%, p < 0.02, Pc = ns). These results suggest that polymorphisms of the MCP-1, CCR2 and CCR5 genes may be associated with T1DM and its complications.

CXC Chemokine Ligand 10 Neutralization Suppresses the Occurrence of Diabetes in Nonobese Diabetic Mice through Enhanced β Cell Proliferation without Affecting Insulitis

We have shown that neutralization of IFN-inducible protein 10/CXCL10, a chemokine for Th1 cells, breaks Th1 retention in the draining lymph nodes, resulting in exacerbation in Th1-dominant autoimmune disease models induced by immunization with external Ags. However, there have been no studies on the role of CXCL10 neutralization in Th1-dominant disease models induced by constitutive intrinsic self Ags. So, we have examined the effect of CXCL10 neutralization using a type 1 diabetes model initiated by developmentally regulated presentation of beta cell Ags. CXCL10 neutralization suppressed the occurrence of diabetes after administration with cyclophosphamide in NOD mice, although CXCL10 neutralization did not significantly inhibit insulitis and gave no influence on the trafficking of effector T cells into the islets. Because both CXCL10 and CXCR3 were, unexpectedly, coexpressed on insulin-producing cells, CXCL10 was considered to affect mature and premature beta cells in an autocrine and/or paracrine fashion. In fact, CXCL10 neutralization enhanced proliferative response of beta cells and resultantly increased beta cell mass without inhibiting insulitis. Thus, CXCL10 neutralization can be a new therapeutic target for beta cell survival, not only during the early stage of type 1 diabetes, but also after islet transplantation.

Tissue-specific effect of estradiol on endothelial cell-dependent lymphocyte recruitment

Estrogen profoundly affects onset and severity of many immune-mediated diseases. In our murine model of drug-induced autoimmunity, female-specific, estrogen-dependent increase in splenic lymphocyte homing was directly implicated in increased disease severity. The present study evaluated the effect of estradiol on microvascular endothelial cells from the spleen compared to endothelial cells from the dermis, which has no disease manifestation in this model. Estradiol increased spleen endothelial cell estrogen receptor (ER) alpha 2.9-fold and decreased estrogen receptor beta 2.1-fold while decreasing both receptors on dermal cells. Estradiol enhanced adhesion of D10 cells to spleen but not dermal endothelial cells 1.53-fold (P < 0.001), an increase that was inhibited by antibodies to VCAM-1 and ICAM-1, and by the estrogen receptor antagonists tamoxifen and ICI 182,780. Estradiol induced greater VCAM-1 expression on spleen than dermal endothelial cells (P < 0.05). Estradiol increased spleen endothelial cell estrogen receptor alpha 2.9-fold and decreased estrogen receptor beta 2.1-fold while decreasing both receptors on the dermal cells. Estrogen specifically and preferentially promoted spleen chemokine protein expression for MCP-1 and MCP-3, while having no effect on dermal protein expression for these chemokines. Estradiol-mediated effects on splenic chemokines were abrogated by tamoxifen and ICI 182,780. The gender-specific increase in lymphocyte homing to spleen may be attributable, at least in part, to tissue-specific estrogen-mediated effects on microvascular endothelial cells.

Analysis of the CCL3-L1 gene for association with HIV-1 susceptibility and disease progression

CCL-L1 binds more potently to CCR5 than any other chemokine; it inhibits HIV-1 infection in vitro, and its gene occurs in variable copy numbers, some individuals failing to produce it. We analysed the frequency of the absence of CCL3-L1 in 268 Caucasian Australian HIV-1 patients and 260 uninfected individuals. A CCL-L1-negative genotype frequency of 2.3% was found in HIV-1 negative individuals. No association was found between the absence of CCL3-L1 and susceptibility to, or rate of progression of, HIV-1 infection.

Insulin-like growth factor (IGF)-I/IGF-binding protein-3 complex: therapeutic efficacy and mechanism of protection against type 1 diabetes

IGF-I regulates islet beta-cell growth, survival, and metabolism and protects against type 1 diabetes (T1D). However, the therapeutic efficacy of free IGF-I may be limited by its biological half-life in vivo. We investigated whether prolongation of its half-life as an IGF-I/IGF binding protein (IGFBP)-3 complex affords increased protection against T1D and whether this occurs by influencing T cell function and/or islet beta-cell growth and survival. Administration of IGF-I either alone or as an IGF-I/IGFBP-3 complex reduced the severity of insulitis and delayed the onset of T1D in nonobese diabetic mice, but IGF-I/IGFBP-3 was significantly more effective. Protection from T1D elicited by IGF-I/IGFBP-3 was mediated by up-regulated CCL4 and down-regulated CCL3 gene expression in pancreatic draining lymph nodes, activation of the phosphatidylinositol 3-kinase and Akt/protein kinase B signaling pathway of beta-cells, reduced beta-cell apoptosis, and stimulation of beta-cell replication. Reduced beta-cell apoptosis resulted from elevated Bcl-2 and Bcl-X(L) activity and diminished caspase-9 activity, indicating a novel role for a mitochondrial-dependent pathway of beta-cell death. Thus, IGF-I/IGFBP-3 affords more efficient protection from insulitis, beta-cell destruction, and T1D than IGF-I, and this complex may represent an efficacious therapeutic treatment for the prevention of T1D.

The stromal cell-derived factor-1alpha/CXCR4 ligand-receptor axis is critical for progenitor survival and migration in the pancreas

The SDF-1α/CXCR4 ligand/chemokine receptor pair is required for appropriate patterning during ontogeny and stimulates the growth and differentiation of critical cell types. Here, we demonstrate SDF-1α and CXCR4 expression in fetal pancreas. We have found that SDF-1α and its receptor CXCR4 are expressed in islets, also CXCR4 is expressed in and around the proliferating duct epithelium of the regenerating pancreas of the interferon (IFN) γ–nonobese diabetic mouse. We show that SDF-1α stimulates the phosphorylation of Akt, mitogen-activated protein kinase, and Src in pancreatic duct cells. Furthermore, migration assays indicate a stimulatory effect of SDF-1α on ductal cell migration. Importantly, blocking the SDF-1α/CXCR4 axis in IFNγ-nonobese diabetic mice resulted in diminished proliferation and increased apoptosis in the pancreatic ductal cells. Together, these data indicate that the SDF-1α–CXCR4 ligand receptor axis is an obligatory component in the maintenance of duct cell survival, proliferation, and migration during pancreatic regeneration.

Use of Microarray Analysis to Unveil Transcription Factor and Gene Networks Contributing to β Cell Dysfunction and Apoptosis

The beta cell fate following immune-mediated damage depends on an intricate pattern of dozens of genes up- or downregulated in parallel and/or sequentially. We are utilizing microarray analysis to clarify the pattern of gene expression in primary rat beta cells exposed to the proapoptotic cytokines, IL-1beta and/or IFN-gamma. The picture emerging from these experiments is that beta cells are not passive bystanders of their own destruction. On the contrary, beta cells respond to damage by activating diverse networks of transcription factors and genes that may either lead to apoptosis or preserve viability. Of note, cytokine-exposed beta cells produce and release chemokines that may contribute to the homing and activation of T cells and macrophages during insulitis. Several of the effects of cytokines depend on the activation of the transcription factor, NF-kappaB. NF-kappaB blocking prevents cytokine-induced beta cell death, and characterization of NF-kappaB-dependent genes by microarray analysis indicated that this transcription factor controls diverse networks of transcription factors and effector genes that are relevant for maintenance of beta cell differentiated status, cytosolic and ER calcium homeostasis, attraction of mononuclear cells, and apoptosis. Identification of this and additional "transcription factor networks" is being pursued by cluster analysis of gene expression in insulin-producing cells exposed to cytokines for different time periods. Identification of complex gene patterns poses a formidable challenge, but is now technically feasible. These accumulating evidences may finally unveil the molecular mechanisms regulating the beta cell "decision" to undergo or not apoptosis in early T1DM.

CC-chemokine receptor CCR5-del32 mutation as a modifying pathogenetic factor in type I diabetes

The purpose of this study was to determine the CCR5-del32 allele frequency in type I (insulin-dependent) and type II (noninsulin-dependent) diabetes patients, and to test whether and how this mutation is associated with both types of diabetes. Thirty-eight type I diabetes and 111 type II diabetes patients' genotyping was performed by polymerase chain reaction assaying, and amplified products were digested with restriction enzyme EcoRI. The results were analyzed using statistical methods. No statistical differences were found in CCR5-del32 allele frequencies in types I and II diabetes patients compared with the control group of native Estonians. However, an association exists between CCR5 gene polymorphism and the clinical course of type I diabetes. In the case of wild-type CCR5, the disease starts at an earlier age. In type II diabetes, there was a difference between genotypes in morbidity to concomitant diseases, being higher in the CCR5 wild-type genotype.

Chemokine receptor CCR5 is not required for development of experimental autoimmune gastritis

Experimental autoimmune gastritis (EAG) is a model of human autoimmune gastritis, the underlying cause of pernicious anaemia. It is characterised by gastric mononuclear cell infiltrates, destruction of parietal and zymogenic cells, and autoantibodies to parietal cell-associated H(+)/K(+) ATPase. Here, we have investigated the role of CCR5 in the development of EAG. We found that the development of EAG was not prevented in CCR5-deficient mice. Using reverse-transcriptase analysis of stomachs from normal and gastritic mice we found no difference in expression of CCR5 and its chemokine ligands MIP-1alpha, MIP-1beta, and RANTES. We also found that the CCR5 antagonist met-RANTES failed to prevent the development of EAG induced by neonatal thymectomy. These observations suggest that the CC chemokine receptor CCR5 is not essential for development of EAG.

Adenovirus transduction induces expression of multiple chemokines and chemokine receptors in murine beta cells and pancreatic islets

Adenoviral vectors are highly efficient for transferring genes to islets. However, the inflammatory and immune responses stimulated by adenovirus may be detrimental to islet survival. Given the role of chemokines and their receptors in inflammation, we analyzed their expression in isolated murine islets, in a murine beta cell line and in syngeneic islet grafts after adenovirus transduction (AdRSVLacZ). AdRSVLacZ transduction enhanced and induced the expression of a variety of chemokines. Transduced syngeneic transplanted islets showed significantly enhanced expression of multiple chemokines and receptors, including monocyte chemoattractant protein-1 (MCP-1), CC chemokine receptor 2 (CCR2) and regulated upon activation, normal T cell expressed and secreted (RANTES), compared with untransduced islet grafts. AdRSVLacZ-transduced islet grafts had significant mononuclear infiltrates, and in situ hybridization demonstrated intragraft expression of MCP-1, CCR2 and RANTES. Although adenovirus transduction did not impair in vitro insulin secretion, diabetes was reversed in only one of six recipients of a marginal mass of AdRSVLacZ-transduced islets, compared with six of six control recipients. In conclusion, multiple chemokines and chemokine receptors are expressed by murine islets constitutively and in response to adenovirus transduction. Adenovirus transduction impairs engraftment of marginal mass of transplanted islets. This is not because of direct vector toxicity of islet secretory capacity, but may be related to host innate immunity in response to adenovirus vector.

Interferon regulatory factor-1 down-regulates cytokine-induced IP-10 expression in pancreatic islets

BACKGROUND

Interferon (IFN)-gamma acts synergistically with interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha to activate isoform of nitric oxide synthetase (iNOS) gene expression, induce apoptosis, and impair glucose-stimulated insulin release (GSIR) in pancreatic islets. This effect is an important mechanism of islet dysfunction in models of pancreatitis, type I diabetes, and islet allograft rejection. We tested the hypothesis that transcription factor interferon regulatory factor (IRF)-1 plays a regulatory role in both this cytokine-induced islet injury and cytokine-induced gene expression for chemotactic chemokines.

METHODS

Isolated islets from wild-type (WT) or IRF-1(-/-) C57BL/6 mice were cultured in a mixture of IL-1beta, TNF-alpha, and IFN-gamma +/- the iNOS inhibitor L-NMMA. The following end points were assessed: i) GSIR; ii) rates of apoptosis; and iii) gene expression for iNOS, IRF-1 and inducible protein (IP)-10, monocyte chemoattractive protein (MCP)-1, macrophage inflammatory protein-1alpha, and macrophage inflammatory protein-1beta.

RESULTS

Cytokine-treated WT islets demonstrated an increase in IRF-1 and iNOS gene expression, inhibition of GSIR, increased rates of apoptosis, and increased gene transcription and protein release for IP-10 and MCP-1. Cytokine-treated IRF-1(-/-) islets demonstrated relatively less iNOS gene expression, preserved GSIR, reduced rates of apoptosis, and a more marked increase in transcription for IP-10 and MCP-1 and in IP-10 protein release. L-NMMA-cotreated WT islets were completely resistant to cytokine-induced dysfunction and apoptosis but demonstrated the same degree of cytokine-induced chemokine gene expression as cytokine-treated WT without L-NMMA.

CONCLUSIONS

IFN-gamma, IL-1beta, and TNF-alpha in combination induce chemokine gene expression in pancreatic islets. Transcription factor IRF-1 mediates cytokine-induced islet dysfunction, apoptosis, and iNOS gene expression but down-regulates IP-10 gene expression.

Acceleration of idiopathic pneumonia syndrome (IPS) in the absence of donor MIP-1 alpha (CCL3) after allogeneic BMT in mice

Idiopathic pneumonia syndrome (IPS) is a significant cause of morbidity and mortality after bone marrow transplantation (BMT) in humans. We developed a murine IPS model in which lethal pre-BMT conditioning and allogeneic T cells results in the recruitment of host monocytes and then donor T cells into the lung by day 7 after BMT, concomitant with development of severe lung dysfunction. We reported the T cell-dependent production of the T cell-attracting chemokine macrophage inflammatory protein-1 alpha (MIP-1 alpha) in the lungs of such recipient mice. We reasoned that MIP-1 alpha might be a critical mediator of IPS. Lethally conditioned mice received transplants of major histocompatibility complex-disparate marrow and either wild-type (MIP-1 alpha(+/+)) or knockout (MIP-1 alpha(-/-)) spleen cells. Recipients of MIP-1 alpha(-/-) cells exhibited accelerated mortality and a decrease in specific compliance that appeared earlier than in recipients of MIP-1 alpha(+/+) cells. Donor CD4(+) and CD8(+) T cell expansion was increased in the spleens of recipients of MIP-1 alpha(-/-) cells. Lungs of recipients of MIP-1 alpha(-/-) cells had earlier recruitment of both T-cell subsets by day 3 after BMT, concomitant with the influx of cells expressing the cytolysins granzymes A and B. Monocyte recruitment was not altered. Levels of inflammatory cytokines were not increased and levels of T cell-attracting chemokines were decreased. The level of the anti-inflammatory cytokine interleukin 13 (IL-13) was lower in the serum and lungs of recipients of MIP-1 alpha(-/-) cells, indicating a skewing toward a more inflammatory T helper cell type 1 (Th1) cytokine milieu. Donor-derived MIP-1 alpha may play a role in allogeneic-induced IPS by limiting aggressive expansion of CD4(+) and CD8(+) T cells.

Proinflammatory cytokines induce NF-kappaB-dependent/NO-independent chemokine gene expression in MIN6 beta cells

BACKGROUND

Interactions between chemokines IP-10, MCP-1, and RANTES and their receptors may mediate graft rejection following islet transplantation. The mechanisms regulating chemokine gene expression in pancreatic islet cells have not been well characterized. We examined the cytokine-induced gene expression profiles for several chemokines in a transformed pancreatic beta-cell line (MIN6) cotreated with an inhibitor of nitric oxide synthase and in a mutated clone of MIN6 made to overexpress a dominant negative inhibitor of NF-kappaB (IkappaBalphaM).

METHODS

MIN6 and MIN6-IkappaBalphaM (Bm) cells were cultured in mixtures of IL-1beta and TNF-alpha or IL-1beta, TNF-alpha, and IFN-gamma plus/minus the iNOS inhibitor L-NMMA. RT-PCR and RNase Protection Assay were used to measure mRNA expression for the following chemokines: IP-10, MIP-1alpha, MIP-1beta, MCP-1, and RANTES. Enzyme linked immunosorbant assay was used to measure IP-10 and MCP-1 protein release.

RESULTS

Cytokine-treated MIN6 and Bm demonstrated increased expression of genes for IP-10 and MCP-1. Expression in MIN6 was first detected at 2 h of incubation and peaked at 6 h. MIN6 demonstrated a more marked increase in chemokine gene expression for both IP-10 and MCP-1 and a more marked increase in IP-10 protein release than did Bm. There was no detectable gene expression for MIP-1alpha, MIP-1beta, or RANTES from MIN6 or Bm. L-NMMA completely blocked NO production from MIN6 and Bm but had no effect on chemokine gene expression in either MIN6 or Bm.

CONCLUSIONS

These results suggest that beta cells produce a complement of rejection-relevant chemokines in response to a proinflammatory stimulus and that pathways governing cytokine-induced chemokine gene expression in MIN6 are dependent on NF-kappaB but independent of NO.

Relation of CD30 molecules on T-cell subsets to the severity of autoimmune thyroid disease

The prognosis of patients with autoimmune thyroid disease (AITD) varies. To clarify the immunologic differences among patients with various severities of AITD, we examined two types of molecules on peripheral T lymphocytes: CD195 (CCR5), which express dominantly on CD4(+) type 1 helper T (T(H)1) cells, and CD30, which is known as a marker of CD4(+) type 2 helper T (T(H)2) cells and a regulatory molecule of CD8(+) autoreactive cytotoxic T cells. We found presence of patients with high proportion (> 9%) of CD30 expression in CD4(+) cells in a group of patients with Graves' disease (GD) in remission compared to the patients with intractable GD and a decrease in the intensity of CD30 expression on CD8(+) cells from patients with severe Hashimoto's disease (HD) treated for hypothyroidism compared to patients with untreated and euthyroid HD. There was no difference in CD195 expression between these patients with GD or HD with different severities, but there was a decreased intensity of CD195(+) cells in thyrotoxic patients with GD. These results indicate that CD30 molecules on CD4(+) and CD8(+) cells may be related to the severities of GD and HD, respectively.

Janus-like role of regulatory iNKT cells in autoimmune disease and tumour immunity

Invariant CD1D-restricted natural killer T (iNKT) cells function during innate and adaptive immunity and regulate numerous immune responses, such as autoimmune disease, tumour surveillance, infectious disease and abortions. However, the molecular basis of their functions and the nature of disease-associated defects of iNKT cells are unclear and have been the subject of recent controversy. Here, we review recent findings that underscore the potential importance of interactions between iNKT cells and dendritic cells (DCs) that indicate that iNKT cells regulate DC activity to shape both pro-inflammatory and tolerogenic immune responses. The ability to modulate iNKT-cell activity in vivo using the ligand alpha-galactosylceramide and to treat patients with autoimmune disease or cancer is evaluated also.

Molecular regulation of monocyte chemoattractant protein-1 expression in pancreatic beta-cells

Pancreatic beta-cells are selectively destroyed during the course of type 1 diabetes. In the early stages of the disease, inflammatory infiltrates of mononuclear cells, containing predominantly monocytes and T-cells, are present in the islets (insulitis). Chemokines, such as monocyte chemoattractant protein-1 (MCP-1), play a key role in the recruitment and activation of these immunocytes. We have previously described cytokine-induced MCP-1 gene expression in human and rat pancreatic islets. In the present study, the transcriptional regulation by cytokines of the rat MCP-1 gene in fluorescence-activated cell sorting-purified rat beta-cells, insulin-producing INS-1E cells, and RINm5F cells was investigated. Transient transfections with luciferase-reporter constructs identified an interleukin (IL)-1beta-responsive enhancer region between -2,180 bp and -2,478 bp. Mutation of either of the two nuclear factor (NF)-kappaB sites present in this region abrogated IL-1beta-induced MCP-1 promoter activity. Binding of NF-kappaB to the two sites was shown in vitro by gel shift assays, while supershift assays revealed the presence of p65/p50 heterodimers and p65 homodimers. In vivo binding of NF-kappaB was confirmed by chromatin immunoprecipitation assay. Blocking of NF-kappaB activation in cytokine-exposed primary beta-cells by an adenovirus overexpressing a nondegradable form of IkappaBalpha or by pyrrolidine dithiocarbamate decreased IL-1beta-induced MCP-1 mRNA expression. We conclude that NF-kappaB plays an important role for MCP-1 expression in beta-cells. This transcription factor may be an interesting target for ex vivo gene therapy before islet transplantation.

Macrophage activating properties of the tryptophan catabolite picolinic acid

Recent studies have suggested a role for aminoacid catabolites as important regulators of macrophage (Mphi) activities. We reported previously that picolinic acid (PA), a tryptophan catabolite produced under inflammatory conditions and a costimulus with IFNgamma of Mphi effector functions, is a selective inducer of the Mphi inflammatory protein-1alpha (MIP-1alpha) and -1beta (MIPs), two CC-chemokines involved in the elicitation of the inflammatory reactions and in the development of the Th1 responses. In this study, we have investigated the effects of IFNgamma on PA-induced MIPs expression and secretion by mouse Mphi as well as the regulation of MIP-1alpha/beta receptor, CCR5, by both stimuli alone or in combination. We demonstrated that IFNgamma inhibited MIPs mRNA stimulation by PA in a dose-and time-dependent fashion, despite its ability to induce other CC- or CXC chemokines. MIPs mRNA down-regulation was associated with decreased intracellular chemokine expression and secretion and was dependent on both mRNA destabilization and gene transcription inhibition. Moreover, IFNgamma inhibitory effects were stimulus-specific because MIPs induction by PA was either unaffected or increased by the anti-inflammatory cytokines, IL-10 and IL-4, or the pro-inflammatory stimulus, LPS, respectively. In contrast, we found that IFNgamma increased CCR5 basal expression, whereas PA down-regulated both constitutive and IFNgamma-induced CCR5 mRNA and protein levels. These results demonstrate that IFNgamma and PA have reciprocal effects on the production of MIPs chemokines and the expression of their receptor. The concerted action of IFNgamma and PA on MIP-1alpha/beta chemokine/receptor system is likely to be of pathophysiological significance and to represent an important regulatory mechanism for leukocyte recruitment and distribution into damaged tissues during inflammatory responses.

Inosine protects against the development of diabetes in multiple-low-dose streptozotocin and nonobese diabetic mouse models of type 1 diabetes

Inosine, a naturally occurring purine, was long considered to be an inactive metabolite of adenosine. However, recently inosine has been shown to be an immunomodulator and anti-inflammatory agent. The aim of this study was to determine whether inosine influences anti-inflammatory effects and affects the development of type 1 diabetes in murine models. Type 1 diabetes was induced either chemically by streptozotocin or genetically using the nonobese diabetic mouse (NOD) model. Mice were treated with inosine (100 or 200 mg kg(-1)d(-1)d) and diabetes incidence was monitored. The effect of inosine on pancreas immune cell infiltration, oxidative stress, and cytokine profile also was determined. For the transplantation model islets were placed under the renal capsule of NOD mice and inosine (200 mg kg(-1)d d(-1)d) treatment started the day of islet transplantation. Graft rejection was diagnosed by return of hyperglycemia accompanied by glucosuria and ketonuria. Inosine reduced the incidence of diabetes in both streptozotocin-induced diabetes and spontaneous diabetes in NOD mice. Inosine decreased pancreatic leukocyte infiltration and oxidative stress in addition to switching the cytokine profile from a Th1 to a Th2 profile. Inosine prolonged pancreatic islet graft survival, increased the number of surviving beta cells, and reduced the number of infiltrating leukocytes. Inosine protects against both the development of diabetes and against the rejection of transplanted islets. The purine exerts anti-inflammatory effects in the pancreas, which is its likely mode of action. The use of inosine should be considered as a potential preventative therapy in humans susceptible to developing Type 1 diabetes and as a possible antirejection therapy for islet transplant recipients.

Chemokines in autoimmunity: from pathology to therapeutics

Leukocyte recruitment, accumulation, and activation have been both a unifying and enigmatic feature of a variety of autoimmune pathologies. While these processes were not well-known for decades, recent scientific discoveries have underscored the importance of specific chemokines in the evolution of autoimmunity. This has been supported by in vivo data from clinical studies and animal model experiments. Although chemokines are an attractive target for drug development, there are hurdles that need to be cleared. Nonetheless, the quest to understand chemokine biology and develop effective therapies continues to capture the imagination of scientists in academia and pharma alike.

Antagonistic effect of picolinic acid and interferon-gamma on macrophage inflammatory protein-1alpha/beta production

The L-tryptophan catabolite, picolinic acid (PA), is an activator of macrophage effector functions and an inducer of macrophage inflammatory protein-1alpha (MIP-1alpha) and -1beta (MIPs). We have investigated the regulation of PA-induced MIPs production in mouse macrophages. We demonstrated a dose- and time-dependent downregulation of MIPs mRNA by the Th1 cytokine, IFN-gamma, that was associated with inhibition of intracellular chemokine production and secretion. This effect was IFN-gamma-specific because MIPs induction was unaffected by the Th2 cytokines, IL-10 and IL-4, or the proinflammatory stimulus, LPS. Moreover, MIPs downregulation by IFN-gamma was dependent on both mRNA destabilization and gene transcription inhibition. These results demonstrate that MIP-1alpha/beta production by macrophages is a tightly regulated process resulting from the interaction between inhibitory stimuli derived from the immune system and stimulatory signals of non-immunologic origin. The antagonistic effect of PA and IFN-gamma on MIPs production may be important for the regulation of the inflammatory responses in vivo.

Reduced expression of Th1-associated chemokine receptors on peripheral blood lymphocytes at diagnosis of type 1 diabetes

We investigated the expression of Th1- and Th2-associated chemokine receptors on peripheral blood lymphocytes at diagnosis and in the first phase of type 1 diabetes. Peripheral blood mononuclear cells (PBMCs) of 25 patients with newly diagnosed type 1 diabetes, 10 patients with longstanding type 1 diabetes, and 35 healthy control subjects were examined for expression of the chemokine receptors CXCR4 (naive T-cells), CCR5 and CXCR3 (Th1 associated), and CCR3 and CCR4 (Th2 associated) on CD3+ lymphocytes. Furthermore, we analyzed chemokine serum levels (monocyte chemoattractant protein [MCP]-1, macrophage inflammatory protein [MIP]-1alpha, MIP-1beta, and RANTES [regulated on activation, normal T-cell expressed and secreted]) and phytohemagglutinin (PHA)-stimulated cytokine secretion of Th1- (gamma-interferon [IFN-gamma] and tumor necrosis factor-alpha [TNF-alpha]) and Th2 (interleukin [IL]-4 and -10)-associated cytokines by PBMC. The patients with newly diagnosed type 1 diabetes were followed for these parameters at 6-12 months after diagnosis. The PBMCs of patients with newly diagnosed but not with longstanding type 1 diabetes showed reduced expression of the Th1-associated chemokine receptors CCR5 (P < 0.001 vs. control subjects) and CXCR3 (P < 0.002 vs. control subjects). This reduction correlated with reduced IFN-gamma and TNF-alpha production of PBMCs after PHA stimulation and reversed 6-12 months after diagnosis to normal levels. CCR4 cells were reduced in both newly diagnosed and longstanding type 1 diabetic patients, which correlated to reduced PHA-stimulated IL-4 production. MIP-1alpha and MIP-1beta levels were considerably elevated in a subgroup of patients with newly diagnosed diabetes. We assume that Th1-associated peripheral T-cells are reduced in a narrow time window at the time of diagnosis of diabetes, possibly due to extravasation in the inflamed pancreas. Thus, chemokine receptor expression of peripheral blood lymphocytes may be a useful surrogate marker for the immune activity of type 1 diabetes (e.g., in intervention trials).

Double-stranded RNA cooperates with interferon-gamma and IL-1 beta to induce both chemokine expression and nuclear factor-kappa B-dependent apoptosis in pancreatic beta-cells: potential mechanisms for viral-induced insulitis and beta-cell death in type 1 diabetes mellitus

Viral infections may trigger the autoimmune assault leading to type 1 diabetes mellitus. Double-stranded RNA (dsRNA) is produced by many viruses during their replicative cycle. The dsRNA, tested as synthetic poly(IC) (PIC), in synergism with the proinflammatory cytokines interferon-gamma (IFN-gamma) and/or IL-1 beta, results in nitric oxide production, Fas expression, beta-cell dysfunction, and death. Activation of the transcription nuclear factor-kappa B (NF-kappa B) is required for PIC-induced inducible nitric oxide synthase expression in beta-cells, and we hypothesized that this transcription factor may also participate in PIC-induced Fas expression and beta-cell apoptosis. This hypothesis, and the possibility that PIC induces expression of additional chemokines and cytokines (previously reported as NF-kappa B dependent) in pancreatic beta-cells, was investigated in the present study. We observed that the PIC-responsive region in the Fas promoter is located between nucleotides -223 and -54. Site-directed mutations at the NF-kappa B and CCAAT/enhancer binding protein-binding sites prevented PIC-induced Fas promoter activity. Increased Fas promoter activity was paralleled by enhanced susceptibility of PIC + cytokine-treated beta-cells to apoptosis induced by Fas ligand. beta-Cell infection with the NF-kappa B inhibitor AdI kappa B((SA)2) prevented both necrosis and apoptosis induced by PIC + IL-1 beta or PIC + IFN-gamma. Messenger RNAs for several chemokines and one cytokine were induced by PIC, alone or in combination with IFN-gamma, in pancreatic beta-cells. These included IP-10, interferon-gamma-inducible protein-10, IL-15, macrophage chemoattractant protein-1, fractalkine, and macrophage inflammatory protein-3 alpha. There was not, however, induction of IL-1 beta expression. We propose that dsRNA, generated during a viral infection, may contribute for beta-cell demise by both inducing expression of chemokines and IL-15, putative contributors for the build-up of insulitis, and by synergizing with locally produced cytokines to induce beta-cell apoptosis. Activation of the transcription factor NF-kappa B plays a central role in at least part of the deleterious effects of dsRNA in pancreatic beta-cells.