-to: Nicoletti F, Conget L, Di Mauro M et al. (2002) Serum concentrations of the interferon-alpha-inducible chemokine IP-10/CXCL10 are augmented in both newly-diagnosed Type I diabetes mellitus patients and subjects at risk of developing the disease. Diabetologia 45:1107-1110

Th1 Chemokines in Autoimmune Endocrine Disorders

CONTEXT

The CXC chemokine receptor CXCR3 and its chemokines CXCL10, CXCL9, and CXCL11 are implicated in the pathogenesis of autoimmune diseases. Here, we review these chemokines in autoimmune thyroiditis (AT), Graves disease (GD), thyroid eye disease (TED), type 1 diabetes (T1D), and Addison's disease (AAD).

EVIDENCE ACQUISITION

A PubMed review of the literature was conducted, searching for the above-mentioned chemokines in combination with AT, GD, TED, T1D, and AAD.

EVIDENCE SYNTHESIS

Thyroid follicular cells in AT and GD, retroorbital cells in TED (fibroblasts, preadipocytes, myoblasts), β cells and islets in T1D, and adrenal cells in AAD respond to interferon-γ (IFN-γ) stimulation producing large amounts of these chemokines. Furthermore, lymphocytes and peripheral blood mononuclear cells (PBMC) are in part responsible for the secreted Th1 chemokines. In AT, GD, TED, T1D, and AAD, the circulating levels of these chemokines have been shown to be high. Furthermore, these chemokines have been associated with the early phases of the autoimmune response in all the above-mentioned disorders. High levels of these chemokines have been associated also with the "active phase" of the disease in GD, and also in TED. Other studies have shown an association with the severity of hypothyroidism in AD, of hyperthyroidism in GD, with severity of TED, or with fulminant T1D.

CONCLUSION

The reviewed data have shown the importance of the Th1 immune response in different endocrine autoimmune diseases, and many studies have suggested that CXCR3 and its chemokines might be considered as potential targets of new drugs for the treatment of these disorders.

Chemokines as Drivers of the Autoimmune Destruction in Type 1 Diabetes: Opportunity for Therapeutic Intervention in Consideration of an Optimal Treatment Schedule

Type 1 diabetes (T1D) is mainly precipitated by the destruction of insulin-producing β-cells in the pancreatic islets of Langerhans by autoaggressive T cells. The etiology of the disease is still not clear, but besides genetic predisposition the exposure to environmental triggers seems to play a major role. Virus infection of islets has been demonstrated in biopsies of T1D patients, but there is still no firm proof that such an infection indeed results in islet-specific autoimmunity. However, virus infection results in a local inflammation with expression of inflammatory factors, such as cytokines and chemokines that attract and activate immune cells, including potential autoreactive T cells. Many chemokines have been found to be elevated in the serum and expressed by islet cells of T1D patients. In mouse models, it has been demonstrated that β-cells express chemokines involved in the initial recruitment of immune cells to the islets. The bulk load of chemokines is however released by the infiltrating immune cells that also express multiple chemokine receptors. The result is a mutual attraction of antigen-presenting cells and effector immune cells in the local islet microenvironment. Although there is a considerable redundancy within the chemokine ligand-receptor network, a few chemokines, such as CXCL10, seem to play a key role in the T1D pathogenesis. Studies with neutralizing antibodies and investigations in chemokine-deficient mice demonstrated that interfering with certain chemokine ligand-receptor axes might also ameliorate human T1D. However, one important aspect of such a treatment is the time of administration. Blockade of the recruitment of immune cells to the site of autoimmune destruction might not be effective when the disease process is already ongoing. By that time, autoaggressive cells have already arrived in the islet microenvironment and a blockade of migration might even hold them in place leading to accelerated destruction. Thus, an anti-chemokine therapy makes most sense in situations where the cells have not yet migrated to the islets. Such situations include treatment of patients at risk already carrying islet-antigen autoantibodies but are not yet diabetic, islet transplantation recipients, and patients that have undergone a T cell reset as occurring after anti-CD3 antibody treatment.

Large-Scale Discovery and Validation Studies Demonstrate Significant Reductions in Circulating Levels of IL8, IL-1Ra, MCP-1, and MIP-1β in Patients With Type 1 Diabetes

CONTEXT

Previous studies have attempted to elucidate the potential role of various cytokines and chemokines in human type 1 diabetes (T1D); however, the precise role of these serum proteins in T1D is still controversial and undetermined primarily due to the small sample sizes of the previous studies. We profiled a panel of serum cytokines and chemokines using a large-scale, two-stage study design for the discovery and validation of the serum proteins associated with T1D.

PARTICIPANTS

The participants were patients with T1D and islet autoantibody-negative control subjects from the Phenome and Genome of Diabetes Autoimmunity study.

MAIN OUTCOME MEASURES

Thirteen cytokines and chemokines were measured in serum of 4424 subjects using multiplex immunoassays.

RESULTS

Using 1378 samples in Stage 1, we found that four of the 13 proteins are significantly lower in patients with T1D than controls (IL8: odds ratio [OR] = 0.40; P = 5.7 × 10(-19); IL-1Ra: OR = 0.42; P = 1.1 × 10(-13); MCP-1: OR = 0.60; P = 6.7 × 10(-9); and MIP-1β: OR = 0.63; P = 4.2 × 10(-7)). Our confirmation data with 3046 samples in Stage 2 further confirmed the significant negative associations of these four proteins with T1D (IL8: OR = 0.43; P = 8.9 × 10(-32); IL-1Ra: OR = 0.56, P = 3.7 × 10(-27); MCP-1: OR = 0.61, P = 4.3 × 10(-17); and MIP-1β: OR = 0.69, P = 2.4 × 10(-13)). Quartile analyses also suggested that significantly more T1D cases have protein levels in the bottom quartile than in the top quartile for all four proteins: IL8 (OR = 0.09), IL-1Ra (OR = 0.18), MCP-1 (OR = 0.38), and MIP-1β (OR = 0.44). Furthermore, the negative associations between T1D and serum levels of all four proteins are stronger in genetically high-risk groups compared with the moderate and low-risk groups.

CONCLUSIONS

IL8, IL-1Ra, MCP-1, and MIP-1β are significantly lower in patients with T1D than controls.

CXCR3, CXCL10 and type 1 diabetes

Type 1 diabetes (T1D) is due to antigen-specific assaults on the insulin producing pancreatic β-cells by diabetogenic T-helper (Th)1 cells. (C-X-C motif) ligand (CXCL)10, an interferon-γ inducible Th1 chemokine, and its receptor, (C-X-C motif) receptor (CXCR)3, have an important role in different autoimmune diseases. High circulating CXCL10 levels were detected in new onset T1D patients, in association with a Th1 autoimmune response. Furthermore β-cells produce CXCL10, under the influence of Th1 cytokines, that suppresses their proliferation. Viral β-cells infections induce cytokines and CXCL10 expression, inducing insulin-producing cell failure in T1D. CXCL10/CXCR3 system plays a critical role in the autoimmune process and in β-cells destruction in T1D. Blocking CXCL10 in new onset diabetes seems a possible approach for T1D treatment.

Chemokine (C-X-C motif) ligand (CXCL)10 in autoimmune diseases

(C-X-C motif) ligand (CXCL)10 (CXCL10) belongs to the ELR(-) CXC subfamily chemokine. CXCL10 exerts its function through binding to chemokine (C-X-C motif) receptor 3 (CXCR3), a seven trans-membrane receptor coupled to G proteins. CXCL10 and its receptor, CXCR3, appear to contribute to the pathogenesis of many autoimmune diseases, organ specific (such as type 1 diabetes, autoimmune thyroiditis, Graves' disease and ophthalmopathy), or systemic (such as rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, mixed cryoglobulinemia, Sjögren syndrome, or systemic sclerosis). The secretion of CXCL10 by cluster of differentiation (CD)4+, CD8+, natural killer (NK) and NK-T cells is dependent on interferon (IFN)-γ, which is itself mediated by the interleukin-12 cytokine family. Under the influence of IFN-γ, CXCL10 is secreted by several cell types including endothelial cells, fibroblasts, keratinocytes, thyrocytes, preadipocytes, etc. Determination of high level of CXCL10 in peripheral fluids is therefore a marker of host immune response, especially T helper (Th)1 orientated T-cells. In tissues, recruited Th1 lymphocytes may be responsible for enhanced IFN-γ and tumor necrosis factor-α production, which in turn stimulates CXCL10 secretion from a variety of cells, therefore creating an amplification feedback loop, and perpetuating the autoimmune process. Further studies are needed to investigate interactions between chemokines and cytokines in the pathogenesis of autoimmune diseases and to evaluate whether CXCL10 is a novel therapeutic target in various autoimmune diseases.

Serum CXCL10 levels and neuromuscular manifestations in patients with autoimmune thyroid diseases

OBJECTIVE

Serum C-X-C motif chemokine 10 (CXCL10) levels have been shown to be elevated in autoimmune thyroid diseases (AITD). This study sought to determine whether newly diagnosed AITD patients with neuromuscular findings had higher levels of CXCL10 than those without neuromuscular manifestations.

DESIGN

A total of 80 patients were recruited to the study, which included treatment-naive hypothyroid Hashimoto's thyroiditis (n = 19) and hyperthyroid Graves' disease (GD; n = 21), euthyroid thyroid autoantibody-positive (n = 20) and -negative (n = 20) patients.

METHODS

All patients underwent a thorough sensorimotor and neuromuscular examination. Serum samples were kept in - 20°C for further CXCL10 measurements with ELISA.

RESULTS

There was a significant difference with regard to serum CXCL10 levels only between GD and euthyroid thyroid autoantibody-negative patient groups [187(12-418) vs. 37.5(2-542) pg/ml, p < 0.05]. However, a comparison of newly diagnosed AITD patients with and without neuromuscular manifestations in terms of serum CXCL10 levels yielded no significant difference. When a correlation of existence of a neuromuscular manifestation and serum CXCL10 levels was evaluated, a significantly positive correlation was noted between carpal tunnel syndrome (CTS) and serum CXCL10 levels [207 (95-748) pg/ml in CTS-positive vs. 117 (2-977) pg/ml in CTS-negative patients, p < 0.05].

CONCLUSIONS

In this study, from a number of neuromuscular manifestations, only the existence of CTS correlated with significantly higher CXCL10 levels in the whole study group. Further studies with larger numbers of patients with autoimmune-based hyper- and hypothyroidism may better clarify the hypothesis regarding a relationship between serum CXCL10 levels and neuromuscular manifestations of AITD.

Enterovirus markers and serum CXCL10 in children with type 1 diabetes

Most patients with type 1 diabetes are considered to have a T-cell mediated autoimmune disease. The chemokine CXCL10 promotes the migration of activated T-cells. Virus infections might contribute to the pathogenesis of type 1 diabetes and enterovirus protein and/or genome have been detected in beta-cells from a majority of tested newly diagnosed children with type 1 diabetes. The chemokine CXCL10 is induced in human islet cells by enterovirus infections in vivo and in vitro, but is not expressed in islets from normal organ donors. Since CXCL10 is a chemokine known to be induced by virus infections and/or cellular damage, our aim was to study if levels of CXCL10 are elevated in serum from children with type 1 diabetes and whether it correlates to the presence of enterovirus markers. CXCL10, neutralizing antibody titer rises against certain enterovirus, and antibodies against GAD65 were measured in serum, and enterovirus PCR was performed on whole blood from 83 type 1 diabetes patients at onset, 48 siblings and 69 controls. CXCL10 was also measured in serum from 46 patients with proven enterovirus infection and in serum from 46 patients with other proven virus infections. The CXCL10 serum levels were not elevated in children at onset of type 1 diabetes and there was a considerable overlap between the groups with 99 (8-498) pg/ml in serum from children with type 1 diabetes, 120 (17-538) pg/ml in serum from controls, and 117 (7-448) pg/ml in siblings of the children with type 1 diabetes. The CXCL10 serum levels in patients with proven enterovirus infection were slightly increased compared to the levels in the other groups, 172 (0-585) pg/ml but there was no statistically significant difference. In contrast, CXCL10 serum levels in patients with other proven virus infections were clearly elevated 418 (34-611) pg/ml. Despite that elevated CXCL10 levels have been demonstrated in some groups of patients with type 1 diabetes, in this study the mean CXCL10 serum levels were not elevated in patients with type 1 diabetes neither in patients with proven enterovirus infection. In contrast, in patients with other virus infections the CXCL10 levels were elevated, presumably reflecting the severity or the site of infection. This suggests that local production of CXCL10 in the affected organ cannot be measured reproducible in serum and that its potential use in clinical practice is limited.

Impaired CD4 and CD8 T cell phenotype and reduced chemokine secretion in recent-onset type 1 diabetic children

Although the role of the T cell-mediated autoimmune reaction in type 1 diabetes (T1D) is conclusive, studies including data from human circulating CD4(+) and CD8(+) lymphocytes subsets during the disease onset and posterior development are scarce. Further, chemokines and chemokine receptors are key players in the migration of pathogenic T cells into the islets of non-obese diabetic mice developing T1D, but few studies have investigated these markers in human T1D patients. We studied the expression of T helper 1 (Th1)- and Th2-associated chemokine receptors, and the two isoforms of CD45 leucocyte antigen on CD4(+) and CD8(+) lymphocytes from T1D and healthy children, as well as the secretion of chemokines in cell supernatants in peripheral blood mononuclear cells. Our results showed increased expression of CCR7 and CD45RA and reduced CD45RO on CD8(+) cells among recent-onset T1D patients. The percentages of CD4(+) cells expressing CXC chemokine receptor 3 (CXCR3), CXCR6 and CCR5, and the secretion of interferon-gamma-induced protein-10, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta was lower among diabetics. Low expression of Th1-associated receptors and secretion of chemokines, together with an increased amount of CD8(+) cells expressing CD45RA and CCR7 in T1D patients therefore might represent suboptimal Th function in T1D, leading to impaired T cytotoxic responses or alternatively reflect a selective recruitment of Th1 cells into the pancreas.

Role of chemokines in endocrine autoimmune diseases

Chemokines are a group of peptides of low molecular weight that induce the chemotaxis of different leukocyte subtypes. The major function of chemokines is the recruitment of leukocytes to inflammation sites, but they also play a role in tumoral growth, angiogenesis, and organ sclerosis. In the last few years, experimental evidence accumulated supporting the concept that interferon-gamma (IFN-gamma) inducible chemokines (CXCL9, CXCL10, and CXCL11) and their receptor, CXCR3, play an important role in the initial stage of autoimmune disorders involving endocrine glands. The fact that, after IFN-gamma stimulation, endocrine epithelial cells secrete CXCL10, which in turn recruits type 1 T helper lymphocytes expressing CXCR3 and secreting IFN-gamma, thus perpetuating autoimmune inflammation, strongly supports the concept that chemokines play an important role in endocrine autoimmunity. This article reviews the recent literature including basic science, animal models, and clinical studies, regarding the role of these chemokines in autoimmune endocrine diseases. The potential clinical applications of assaying the serum levels of CXCL10 and the value of such measurements are reviewed. Clinical studies addressing the issue of a role for serum CXCL10 measurement in Graves' disease, Graves' ophthalmopathy, chronic autoimmune thyroiditis, type 1 diabetes mellitus, and Addison's disease have been considered. The principal aim was to propose that chemokines, and in particular CXCL10, should no longer be considered as belonging exclusively to basic science, but rather should be used for providing new insights in the clinical management of patients with endocrine autoimmune diseases.