Chemokines and chemokine receptors in inflammatory demyelinating neuropathies: a central role for IP-10

Defective autoimmune regulator-dependent central tolerance to myelin protein zero is linked to autoimmune peripheral neuropathy

Chronic inflammatory demyelinating polyneuropathy is a debilitating autoimmune disease characterized by peripheral nerve demyelination and dysfunction. How the autoimmune response is initiated, identity of provoking Ags, and pathogenic effector mechanisms are not well defined. The autoimmune regulator (Aire) plays a critical role in central tolerance by promoting thymic expression of self-Ags and deletion of self-reactive T cells. In this study, we used mice with hypomorphic Aire function and two patients with Aire mutations to define how Aire deficiency results in spontaneous autoimmune peripheral neuropathy. Autoimmunity against peripheral nerves in both mice and humans targets myelin protein zero, an Ag for which expression is Aire-regulated in the thymus. Consistent with a defect in thymic tolerance, CD4(+) T cells are sufficient to transfer disease in mice and produce IFN-γ in infiltrated peripheral nerves. Our findings suggest that defective Aire-mediated central tolerance to myelin protein zero initiates an autoimmune Th1 effector response toward peripheral nerves.

Translational strategies in peripheral neuroinflammation and neurovascular repair

Current therapies for immune-mediated inflammatory disorders in peripheral nerves are non-specific, and partly efficacious. Peripheral nerve regeneration following axonal degeneration or injury is suboptimal, with current therapies focused on modulating the underlying etiology and treating the consequences, such as neuropathic pain and weakness. Despite significant advances in understanding mechanisms of peripheral nerve inflammation, as well as axonal degeneration and regeneration, there has been limited translation into effective new drugs for these disorders. A major limitation in the field has been the unavailability of reliable disease models or research tools that mimic some key essential features of these human conditions. A relatively overlooked aspect of peripheral nerve regeneration has been neurovascular repair required to restore the homeostatic microenvironment necessary for normal function. Using Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) as examples of human acute and chronic immune-mediated peripheral neuroinflammatory disorders respectively, we have performed detailed studies in representative mouse models to demonstrate essential features of the human disorders. These models are important tools to develop and test treatment strategies using realistic outcomes measures applicable to affected patients. In vitro models of the human blood-nerve barrier using endothelial cells derived by endoneurial microvessels provide insights into pro-inflammatory leukocyte-endothelial cell interactions relevant to peripheral neuroinflammation, as well as potential mediators and signaling pathways required for vascular proliferation, angiogenesis, remodeling and tight junction specialization necessary to restore peripheral nerve function following injury. This review discusses the progress we are making in translational peripheral neurobiology and our future directions.

Nerve biopsy in chronic inflammatory neuropathies: in situ biomarkers

We collected the evidence for potential biomarkers in nerve biopsies that might be of use in diagnosis, assessment, or treatment response in chronic inflammatory demyelinating polyneuropathies (CIDPs). We performed a literature search in PubMed from 1965 to May 2010 using the key words (["chronic inflammatory polyneuropathy" or "polyradiculoneuritis" or {"chronic and neuritis"}] and "nerve biopsy") and searched manually within these references for relevant publications related to the subject. Twenty references gave information about potential biomarkers for CIDP. Evidence of demyelination alone is not specific for CIDP, but may support the diagnosis in the context of a typical clinical pattern. Although the total numbers of inflammatory cells do not distinguish well between CIDP and non-inflammatory neuropathies, the pattern of macrophage clusters around endoneurial vessels may be a simple marker of inflammation with good sensitivity and specificity. Immunohistochemistry for matrix metalloproteinase-9 may be useful for the distinction of inflammatory and non-inflammatory neuropathies. Microarrays which give a complex pattern of up- and downregulated genes also show promise for developing a biomarker. Immunohistochemistry on sural nerve biopsies has the potential to distinguish inflammatory from non-inflammatory neuropathies. More research is needed to establish the diagnostic validity of specific markers and of gene expression studies and to test whether they can distinguish between subtypes of inflammatory neuropathies.

Advances in the diagnosis, pathogenesis and treatment of CIDP

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common chronic autoimmune neuropathy. Despite clinical challenges in diagnosis-owing in part to the existence of disease variants, and different views on how many electrophysiological abnormalities are needed to document demyelination-consensus criteria seem to have been reached for research or clinical practice. Current standard of care involves corticosteroids, intravenous immunoglobulin (IVIg) and/or plasmapheresis, which provide short-term benefits. Maintenance therapy with IVIg can induce sustained remission, increase quality of life and prevent further axonal loss, but caution is needed to avoid overtreatment. Commonly used immunosuppressive drugs offer minimal benefit, necessitating the development of new therapies for treatment-refractory patients. Advances in our understanding of the underlying immunopathology in CIDP have identified new targets for future therapeutic efforts, including T cells, B cells, and transmigration and transduction molecules. New biomarkers and scoring systems represent emerging tools with the potential to predict therapeutic responses and identify patients with active disease for enrollment into clinical trials. This Review highlights the recent advances in diagnosing CIDP, provides an update on the immunopathology including new target antigens, and discusses current treatments, ongoing challenges and future therapeutic directions.

Posterior reversible encephalopathy syndrome resulting from Guillain-Barré-like syndrome secondary to West Nile virus infection

A 67-year-old woman developed hypertension, drowsiness, hemianopia, ascending flaccid tetraparesis, and areflexia. Nerve conduction studies revealed a demyelinating polyneuropathy. Brain magnetic resonance imaging demonstrated hyperintense white matter lesions. IgM antibodies against West Nile virus were positive. She was treated for hypertension and with intravenous immunoglobulins and recovered completely within 2 months. To our knowledge, this is the first case in which West Nile virus infection presented as posterior reversible encephalopathy syndrome associated with Guillain-Barré-like syndrome.

Autoimmune diseases of the peripheral nervous system

Autoimmune-mediated diseases targeting the peripheral nerve represent a group of disorders often associated with high clinical disability. At present, therapeutic options are limited. The application of innovative and cutting-edge technologies to the study of immune-mediated disorders of the peripheral nervous system (PNS) have generated a better understanding of underlying principles of the organization of the immune network present in the peripheral nerve and its dialogue with the systemic immune system. These insights may foster the development of specific and highly effective therapies for autoimmune diseases of the peripheral nerve. Of great interest in this context is the application of monoclonal antibodies, such as rituximab or alemtuzumab, which in small observational studies provided promising clinical results. But also other immunomodulatory or immunosuppressive drugs used in other indications currently find their way to PNS autoimmunity. Clearly, prospective controlled clinical trials are warranted before making firm conclusions on the feasibility of these innovative therapeutic approaches for treating immune-mediated disease of the peripheral nerve.

Decreased CXCR3 expression in CD4+ T cells exposed to asbestos or derived from asbestos-exposed patients

Asbestos causes malignant tumors such as lung cancer and malignant mesothelioma (MM). To determine whether asbestos exposure causes reduction of antitumor immunity, we established an in vitro T-cell line model of low-dose and continuous exposure to asbestos using an human adult T-cell leukemia virus-1 immortalized human polyclonal T-cell line, MT-2, and revealed that MT-2 cells exposed continuously to asbestos showed resistance to asbestos-induced apoptosis. In addition, the cells presented reduction of surface CXCR3 chemokine receptor expression and IFN-γ production. In this study, to confirm that these findings are suitable for clinical translation, surface CXCR3 and IFN-γ expression were analyzed using freshly isolated human CD4(+) T cells derived from healthy donors and patients with pleural plaque (PP) or MM. The results revealed that CXCR3 and IFN-γ expression in the ex vivo model were reduced in some cases. Additionally, CXCR3 expression in CD4(+) T cells from PPs and MMs was significantly reduced compared with that from healthy donors, and CD4(+) T cells from patients with MMs exhibited a marked reduction in IFN-γ mRNA levels after stimulation in vitro. Moreover, CD4(+)CXCR3(+) T cells in lymphocytes from MMs showed a tendency for an inverse correlation with its ligand CXCL10/IP10 in plasma. These findings show reduction of antitumor immune function in asbestos-exposed patients and indicate that CXCR3, IFN-γ, and CXCL10/IP10 may be candidates to detect and monitor disease status.

The role of cytokines in Guillain-Barré syndrome

Cytokines play an important role in the pathogenesis of autoimmune diseases including Guillain-Barré syndrome (GBS) and its animal model experimental autoimmune neuritis (EAN). In this article, we reviewed the current knowledge of the role of cytokines such as TNF-α, IFN-γ, IL-1β, IL-6, IL-12, IL-18, IL-23, IL-17, IL-10, IL-4 and chemokines in GBS and EAN as unraveled by studies both in the clinic and the laboratory. However, these studies occasionally yield conflicting results, highlighting the complex role that cytokines play in the disease process. Efforts to modulate cytokine function in GBS and other autoimmune disease have shown efficiency indicating that cytokines are important therapeutic targets.

Plasma exchange and intravenous immunoglobulins: mechanism of action in immune-mediated neuropathies

Immune-mediated neuropathies are a heterogeneous group of peripheral nerve disorders, which are classified by time course, clinical pattern, affected nerves and pathological features. Plasma exchange (PE) and intravenous immunoglobulins (IVIg) are mainstays in the treatment of immune-mediated neuropathies. Of all treatments currently used, IVIg has probably the widest application range in immune-mediated neuropathies and efficacy has been well documented in several randomized controlled trials for Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy (CIDP). Beneficial effects of IVIg have also been proven for multifocal motor neuropathy (MMN). Likewise, PE is an established treatment for GBS and CIDP, whereas it is considered to be ineffective in MMN. Different mechanisms of action are sought to be responsible for the immunemodulatory effect of PE and IVIg in autoimmune disorders. Some of those might be important for immune-mediated neuropathies, while others are probably negligible. The aim of this review is to summarize the recent advances in elucidating disease-specific mechanisms of actions of PE and IVIg in the treatment of immune-mediated neuropathies.

The blood-brain barrier, chemokines and multiple sclerosis

The infiltration of leukocytes into the central nervous system (CNS) is an essential step in the neuropathogenesis of multiple sclerosis (MS). Leukocyte extravasation from the bloodstream is a multistep process that depends on several factors including fluid dynamics within the vasculature and molecular interactions between circulating leukocytes and the vascular endothelium. An important step in this cascade is the presence of chemokines on the vascular endothelial cell surface. Chemokines displayed along the endothelial lumen bind chemokine receptors on circulating leukocytes, initiating intracellular signaling that culminates in integrin activation, leukocyte arrest, and extravasation. The presence of chemokines at the endothelial lumen can help guide the movement of leukocytes through peripheral tissues during normal immune surveillance, host defense or inflammation. The expression and display of homeostatic or inflammatory chemokines therefore critically determine which leukocyte subsets extravasate and enter the peripheral tissues. Within the CNS, however, infiltrating leukocytes that cross the endothelium face additional boundaries to parenchymal entry, including the abluminal presence of localizing cues that prevent egress from perivascular spaces. This review focuses on the differential display of chemokines along endothelial surfaces and how they impact leukocyte extravasation into parenchymal tissues, especially within the CNS. In particular, the display of chemokines by endothelial cells of the blood brain barrier may be altered during CNS autoimmune disease, promoting leukocyte entry into this immunologically distinct site. Recent advances in microscopic techniques, including two-photon and intravital imaging have provided new insights into the mechanisms of chemokine-mediated capture of leukocytes within the CNS.

Appearance of Cxcl10-expressing cell clusters is common for traumatic brain injury and neurodegenerative disorders

Traumatic brain injury (TBI) in the mouse results in the rapid appearance of scattered clusters of cells expressing the chemokine Cxcl10 in cortical and subcortical areas. To extend the observation of this unique pattern, we used neuropathological mouse models using quantitative reverse transcriptase-polymerase chain reaction, gene array analysis, in-situ hybridization and flow cytometry. As for TBI, cell clusters of 150-200 mum expressing Cxcl10 characterize the cerebral cortex of mice carrying a transgene encoding the Swedish mutation of amyloid precursor protein, a model of amyloid Alzheimer pathology. The same pattern was found in experimental autoimmune encephalomyelitis in mice modelling multiple sclerosis. In contrast, mice carrying a SOD1(G93A) mutant mimicking amyotrophic lateral sclerosis pathology lacked such cell clusters in the cerebral cortex, whereas clusters appeared in the brainstem and spinal cord. Mice homozygous for a null mutation of the Cxcl10 gene did not show detectable levels of Cxcl10 transcript after TBI, confirming the quantitative reverse transcriptase-polymerase chain reaction and in-situ hybridization signals. Moreover, unbiased microarray expression analysis showed that Cxcl10 was among 112 transcripts in the neocortex upregulated at least threefold in both TBI and ageing TgSwe mice, many of them involved in inflammation. The identity of the Cxcl10(+) cells remains unclear but flow cytometry showed increased numbers of activated microglia/macrophages as well as myeloid dendritic cells in the TBI and experimental autoimmune encephalomyelitis models. It is concluded that the Cxcl10(+) cells appear in the inflamed central nervous system and may represent a novel population of cells that it may be possible to target pharmacologically in a broad range of neurodegenerative conditions.

Posterior reversible encephalopathy syndrome as a complication of Guillain-Barré syndrome

Posterior reversible encephalopathy syndrome (PRES) is characterised by sudden hypertension that is associated with headache, seizure, visual disturbance and altered mental function. We report a 62-year-old woman with a sudden onset of complete bilateral visual loss, an admission blood pressure (BP) of 204/113mmHg, and flaccid weakness in all four limbs. The patient's cerebrospinal fluid and nerve conduction studies were consistent with a diagnosis of Guillain-Barré syndrome (GBS) and her brain MRI showed classic features of PRES. Her blood pressure was managed appropriately and her GBS was treated with plasmapheresis. Two months following presentation, the patient's vision recovered completely and she regained full power of her four limbs. She did not need any continuing antihypertensive medication. This report is the 8th of accumulating evidence that links PRES with GBS, and it shows that PRES can be the presenting feature following GBS treatment with intravenous (IV) immunoglobulins or later in recovery. Dysautonomia resulting from GBS is the most likely explanation of this strong association. GBS is mostly reversible when managed correctly; however, the literature suggests that failure to recognize or delay treatment can lead to cerebral infarction or even death.

Chronic inflammatory demyelinating polyradiculoneuropathy: diagnostic and therapeutic challenges for a treatable condition

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a chronic neuropathy of supposed immune origin. Understanding of its pathophysiology has recently improved, although its causes remain unclear. The classic presentation of CIDP includes sensory and motor symptoms in the distal and proximal segments of the four limbs with areflexia, evolving over more than 8 weeks. Raised protein concentrations in CSF and heterogeneous slowing of nerve conduction are typical of the condition. In addition to this usual phenotype, distribution of symptoms, disease course, and disability can be heterogeneous, leading to underdiagnosis of the disorder. Diagnosis is sometimes challenging and can require use of imaging and nerve biopsy. Steroids and intravenous immunoglobulin are effective, and plasma exchange can be helpful as rescue therapy. The usefulness of immunosuppressants needs to be established. The identification of specific diagnostic markers and new therapeutic strategies with conventional or targeted immunotherapy are needed to improve the outlook for patients with CIDP.

Dipyrithione inhibits IFN-gamma-induced JAK/STAT1 signaling pathway activation and IP-10/CXCL10 expression in RAW264.7 cells

Objective

This study investigates the effects of dipyrithione (PTS2) on the expression of IP-10/CXCL10, which has been observed in a wide variety of chronic inflammatory disorders and autoimmune conditions.

Methods

RAW264.7 cells (a murine macrophage-like cell line) were cultured in the absence or in the presence of PTS2 (3–10 μM) together with or without IFN-γ (10 ng/ml). IP-10/CXCL10 expression was measured by specific enzyme-amplified immunoassays and reverse transcriptase-PCR (RT-PCR). Phosphorylation of JAK1, JAK2 and STAT1 were detected by Western blot analysis.

Results

We found that PTS2 inhibited IFN-γ-induced up-regulation of IP-10/CXCL10 protein level in a dose- and time-dependent manner in RAW264.7 cells. RT-PCR experiments showed that PTS2 suppressed IFN-γ-induced IP-10/CXCL10 expression at mRNA levels. Mechanistically, PTS2 prevented phosphorylation of JAK1, JAK2 and STAT1, but did not interfere with the p38 pathway. Furthermore, the inhibitory effect of PTS2 on IP-10/CXCL10 up-regulation was slightly stronger than JAK2 inhibitor AG490.

Conclusion

PTS2 inhibits IFN-γ-induced IP-10/CXCL10 expression in RAW264.7 cells by targeting the JAK/STAT1 signaling pathway, suggesting that PTS2 could exert anti-inflammatory effects through attenuating the formation of chemokine IP-10/CXCL10.

Epidemiologic investigation of immune-mediated polyradiculoneuropathy among abattoir workers exposed to porcine brain

Background

In October 2007, a cluster of patients experiencing a novel polyradiculoneuropathy was identified at a pork abattoir (Plant A). Patients worked in the primary carcass processing area (warm room); the majority processed severed heads (head-table). An investigation was initiated to determine risk factors for illness.

Methods and Results

Symptoms of the reported patients were unlike previously described occupational associated illnesses. A case-control study was conducted at Plant A. A case was defined as evidence of symptoms of peripheral neuropathy and compatible electrodiagnostic testing in a pork abattoir worker. Two control groups were used - randomly selected non-ill warm-room workers (n = 49), and all non-ill head-table workers (n = 56). Consenting cases and controls were interviewed and blood and throat swabs were collected. The 26 largest U.S. pork abattoirs were surveyed to identify additional cases. Fifteen cases were identified at Plant A; illness onsets occurred during May 2004–November 2007. Median age was 32 years (range, 21–55 years). Cases were more likely than warm-room controls to have ever worked at the head-table (adjusted odds ratio [AOR], 6.6; 95% confidence interval [CI], 1.6–26.7), removed brains or removed muscle from the backs of heads (AOR, 10.3; 95% CI, 1.5–68.5), and worked within 0–10 feet of the brain removal operation (AOR, 9.9; 95% CI, 1.2–80.0). Associations remained when comparing head-table cases and head-table controls. Workers removed brains by using compressed air that liquefied brain and generated aerosolized droplets, exposing themselves and nearby workers. Eight additional cases were identified in the only two other abattoirs using this technique. The three abattoirs that used this technique have stopped brain removal, and no new cases have been reported after 24 months of follow up. Cases compared to controls had higher median interferon-gamma (IFNγ) levels (21.7 pg/ml; vs 14.8 pg/ml, P<0.001).

Discussion

This novel polyradiculoneuropathy was associated with removing porcine brains with compressed air. An autoimmune mechanism is supported by higher levels of IFNγ in cases than in controls consistent with other immune mediated illnesses occurring in association with neural tissue exposure. Abattoirs should not use compressed air to remove brains and should avoid procedures that aerosolize CNS tissue. This outbreak highlights the potential for respiratory or mucosal exposure to cause an immune-mediated illness in an occupational setting.

Chronic inflammatory demyelinating polyradiculoneuropathy: a role for haematopoietic stem cell transplantation?

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a clinical syndrome of a chronic progressive or relapsing and remitting, symmetrical, sensory and motor radiculoneuropathy. The immune reaction in CIDP is characterised by selective inflammation of peripheral nerves and is probably due to the interaction of cellular and humoral responses. Only three treatments for CIDP have demonstrated benefit in randomised studies, corticosteroids, plasma exchange and intravenous immunoglobulin. 25% of patients fail to respond or do not respond adequately to these treatments. Experimental data in animal models have shown that several autoimmune disorders, either congenital or acquired, can be transferred and/or treated by the transplantation of bone marrow stem cells. Haematopoietic stem cell transplantation (HSCT) has been performed with varying success in over 700 patients with autoimmune disorders throughout Europe. The experience in CIDP is very limited. This article will review current understanding of CIDP and experience of the use of HSCT in refractory CIDP.

pSTAT1, pSTAT3, and T-bet as markers of disease activity in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is considered an auto-immune disorder. We evaluated expression of pSTAT1, T-bet, and pSTAT3 in circulating T-cells, B-cells, and monocytes and spontaneous production of interleukin-17 (IL17), interferon-gamma (IFN gamma), and interleukin-10 (IL10) by peripheral blood mononuclear cells (PBMCs) from 14 active CIDP patients compared with 6 patients with long-lasting remission and 20 controls. Active disease patients showed higher pSTAT1, T-bet, and pSTAT3 in CD4(+) T-cells than controls (p < 0.001, p = 0.0002, p = 0.0097, respectively) and remission patients (p < 0.001, p = 0.0036, p = 0.0008, respectively). pSTAT1, T-bet, and pSTAT3 were also higher in monocytes from active CIDP patients than controls (p = 0.0011, p = 0.0041, p = 0.0413, respectively) and remission patients (p = 0.0073, p = 0.0274, p = 0.0251, respectively). Moreover in CD8(+) T-cells, pSTAT3 expression was higher in active CIDP patients than in remission patients (p = 0.0345) and in controls (p = 0.0023). IL17 and IFN gamma production were significantly higher in active CIDP patients than in controls (p < 0.0395, p = 0.0010, respectively); IFN gamma levels were higher also in remission CIDP patients (p = 0.0073). IL10 levels were higher in active phase patients than in controls (p = 0.0334). Our data suggest that pSTAT1, T-bet, and pSTAT3 can be considered putative markers of disease activity and potential targets for specific therapies.

Targeting of myelin protein zero in a spontaneous autoimmune polyneuropathy

Elimination of the costimulatory molecule B7-2 prevents autoimmune diabetes in NOD mice, but leads to the development of a spontaneous autoimmune polyneuropathy (SAP), which resembles the human disease chronic inflammatory demyelinating polyneuropathy (CIDP). In this study, we examined the immunopathogenic mechanisms in this model, including identification of SAP Ags. We found that B7-2-deficient NOD mice exhibit changes in cytokine and chemokine gene expression in spleens over time. There was an increase in IL-17 and a decrease in IL-10 transcript levels at 4 mo (preclinical phase), whereas IFN-gamma expression peaked at 8 mo (clinical phase). There was also an increase in transcript levels of Th1 cytokines, CXCL10, and RANTES in sciatic nerves of mice that developed SAP. Splenocytes from SAP mice exhibited proliferative and Th1 cytokine responses to myelin P0 (180-199), but not to other P0 peptides or P2 (53-78). Adoptive transfer of P0-reactive T cells generated from SAP mice induced neuropathy in four of six NOD.SCID mice. Data from i.v. tolerance studies indicate that myelin P0 is one of the autoantigens targeted by T cells in SAP in this model. The expression of P0 by peri-islet Schwann cells provides a potential mechanism linking islet autoimmunity and inflammatory neuropathy.

Distinct cellular patterns of upregulated chemokine expression supporting a prominent inflammatory role in traumatic brain injury

Cerebral gene expressions change in response to traumatic brain injury (TBI), and future trauma treatment may improve with increased knowledge about these regulations. We subjected C57BL/6J mice to injury by controlled cortical impact (CCI). At various time points post-injury, mRNA from neocortex and hippocampus was isolated, and transcriptional alterations studied using quantitative real-time polymerase chain reaction (PCR) and gene array analysis. Spatial distribution of enhanced expression was characterized by in situ hybridization. Products of the upregulated transcripts serve functions in a range of cellular mechanisms, including stress, inflammation and immune responses, and tissue remodeling. We also identified increased transcript levels characterizing reactive astrocytes, oligodendrocytes, and microglia, and furthermore, we demonstrated a novel pattern of scattered cell clusters expressing the chemokine Cxcl10. Notably, a sustained increase in integrin alpha X (Itgax), characterizing antigen-presenting dendritic cells, was found with the transcript located to similar cell clusters. In contrast, T-cell receptor alpha transcript showed only a modest increase. The induced P-selectin (Selp) expression level in endothelial cells, and chemokines from microglia, may guide perivascular accumulation of extravasating inflammatory monocytes differentiating into dendritic cells. In conclusion, our study shows that following TBI, secondary injury chiefly involves inflammatory processes and chemokine signaling, which comprise putative targets for pharmaceutical neuroprotection.

Intravenous immunoglobulins in the treatment of immune neuropathies

PURPOSE OF REVIEW

The aim of this review is to describe the value of high-dose polyclonal intravenous immunoglobulins as a treatment option in autoimmune disorders affecting the peripheral nervous system.

RECENT FINDINGS

A randomized placebo-controlled trial in patients with chronic inflammatory demyelinating polyradiculoneuropathy revealed short-term and long-term efficacy and safety of intravenous immunoglobulins as a treatment option for the chronically inflamed peripheral nervous system. Case reports suggest that the subcutaneous administration of immunoglobulins may represent a convenient alternative.

SUMMARY

Intravenous immunoglobulin represents an effective and safe treatment option in patients with autoimmune-mediated diseases affecting the peripheral nerves.

Chronic CXCL10 alters the level of activated ERK1/2 and transcriptional factors CREB and NF-kappaB in hippocampal neuronal cell culture

Signal transduction pathways may be important targets of chemokines during neuroinflammation. In the current study, Western blot analyses show that in rat hippocampal neuronal/glial cell cultures chronic CXCL10 increases the level of protein for ERK1/2 as well as for the transcriptional factors CREB and NF-kappaB. Bcl-2, an anti-apoptotic protein whose expression can be regulated by a pathway involving ERK1/2, CREB and NF-kappaB, was also increased in the CXCL10 treated cultures. These results implicate a role for ERK1/2, CREB and NF-kappaB in effects of CXCL10 on hippocampal cells and suggest that chronic CXCL10 may have a protective role during certain neuroinflammatory conditions.

Therapeutic neutralization of CXCL10 decreases secondary degeneration and functional deficit after spinal cord injury in mice

Inflammation plays a critical role in the secondary degenerative response to spinal cord injury (SCI). The influx of inflammatory cells following SCI is preceded by the expression of specific chemoattractants, including chemokines. The chemokine CXCL10 is a potent T lymphocyte recruiter and has been strongly implicated in the pathology of many CNS disorders. We have previously demonstrated that CXCL10 exacerbates secondary degeneration by blocking the function of CXCL10 prior to SCI. Here we administered neutralizing antibodies against CXCL10 1 h after SCI in order to investigate the efficacy of this therapeutic intervention in abating histologic and functional deficit following acute SCI and further assess the functional role of CXCL10 in secondary degeneration. Neutralization of CXCL10 significantly reduced inflammation, apoptosis, neuronal loss and whole tissue loss. Notably, this therapeutic treatment also promoted revascularization of the injured spinal cord and functional recovery. These data suggest that anti-CXCL10 antibody treatment is a viable therapeutic strategy for acute SCI.

From bench to bedside--experimental rationale for immune-specific therapies in the inflamed peripheral nerve

Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy are autoimmune-mediated inflammatory diseases of the PNS. In recent years, substantial progress has been made towards understanding the immune mechanisms that underlie these conditions, in large part through the study of experimental models. Here, we review the available animal models that partially mimic human Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy, and discuss the wide range of therapeutic approaches that have been successfully established in these models of inflammatory neuropathies. Transfer of this preclinical knowledge to patients has been far less successful, and inflammatory neuropathies are still associated with significant morbidity and mortality. We will summarize successful therapeutic trials in human autoimmune neuropathies to provide a vantage point for the transfer of experimental treatment strategies to clinical practice in immune-mediated diseases of the peripheral nerve.

Immune circuitry in the peripheral nervous system

PURPOSE OF REVIEW

The aim of this review is to describe the local immune circuitry in the peripheral nervous system and its dialogue with systemic immunity under pathological conditions. Specifically, interactions of the immune system with cellular and extracellular components within peripheral nerve and immune functions of tissue-resident endoneurial macrophages and Schwann cells will be discussed.

RECENT FINDINGS

New insights into the elements involved in the pathogenesis of immune-mediated disorders of the peripheral nervous system provide a better understanding of the complex interplay of these cellular and molecular components in the immunology of the peripheral nervous system.

SUMMARY

The application of innovative and cutting-edge technologies to the study of immunoinflammatory disorders of the peripheral nervous system provides a better understanding of underlying principles of the organization of the immune network present in the peripheral nerve and its dialogue with the systemic immune system. This may foster the development of specific and highly effective therapies for immune-mediated disorders of the peripheral nerve.

Challenge with innate and protein antigens induces CCR7 expression by microglia in vitro and in vivo

Since activated microglia are able to phagocytose damaged cells and subsequently express major histocompatibility complex class II (MHC-II) and co-stimulatory proteins, they are considered to function as antigen presenting cells (APCs) in the central nervous system. The maturation and migratory potential of professional APCs is associated with the expression of chemokine receptor CCR7. We therefore investigated whether the immunological activation of microglia induces CCR7 expression. We here present that activation of cultured microglia by both the innate antigen lipopolysaccharide and protein antigen ovalbumin rapidly induces CCR7 expression, accompanied by increased MHC-II expression. Moreover, it is shown that CCR7 expression in IBA-1 positive cells is induced during the symptom onset and progression of experimental autoimmune encephalomyelitis, a rodent model for multiple sclerosis. These results suggest that microglia express CCR7 under specific inflammatory conditions, corroborating the idea that microglia develop into APCs with migratory potential toward lymphoid chemokines.

Posterior reversible encephalopathy and Guillain-Barré syndrome in a single patient: Coincidence or causative relation?

We report 62-year-old female patient with coincident posterior reversible encephalopathy syndrome (PRES) and Guillain-Barré syndrome (GBS). The first presentation of PRES was a generalised tonic-clonic seizure. A risk factor for PRES was acute arterial hypertension. The diagnosis of PRES was established by MRI (magnetic resonance imaging) and hypertension was treated with labetalol 800mg daily followed by regression of symptoms of PRES. Two days after the seizure the first motor signs of GBS presented with a weakness in both upper arms. The diagnosis of GBS was finally established 6 days after the seizure by clinical evolution, lumbar puncture and electrophysiological findings. After treatment of GBS with intravenous immunoglobulins (IVIg), antihypertensive therapy could be phased out and finally stopped. The patient was discharged after 25 days without any medication. At that time she was completely recovered from PRES and recovering well from GBS. The acute arterial hypertension, the provoking factor of PRES, was probably caused by an autonomic dysfunction in the context of GBS before motor signs of GBS were present but we speculate also that there are other GBS related factors playing a role in PRES. This hypothesis is based on the relatively high coincidence of these two rare syndromes which appears from a review of the literature. One other possible mechanism can be the influence of cytokines, produced in the context of a GBS, on the permeability of blood brain barrier.

Serum and cerebral spinal fluid levels of chemokines and Th2 cytokines in Schistosoma mansoni myeloradiculopathy

Schistosomal myeloradiculopathy (SMR) is the most common neurological form of Schistosoma mansoni infection. In this study we investigated the expression of chemokines and Th2 cytokines in serum and cerebral spinal fluid (CSF) of SMR patients. SMR patients presented increased serum levels of CCL11/eotaxin and CCL24/eotaxin-2 when compared to controls. SMR patients also had higher levels of IL-13 in CSF. Thus, SMR patients present enhancement of both IL-13 and CCR3 acting chemokines, both of which may facilitate the expression of a Th2 response and Th2-dependent damage to the spinal cord. As this cytokine is responsible for promoting Th2 responses, this finding is in accordance to the view that Th2 cells are important in the immunological process against the S. mansoni.

Pathogenesis of chronic inflammatory demyelinating polyradiculoneuropathy

The acute lesions of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) consist of endoneurial foci of chemokine and chemokine receptor expression and T cell and macrophage activation. The myelin protein antigens, P2, P0, and PMP22, each induce experimental autoimmune neuritis in rodent models and might be autoantigens in CIDP. The strongest evidence incriminates P0, to which antibodies have been found in 20% of cases. Failure of regulatory T-cell mechanism is thought to underlie persistent or recurrent disease, differentiating CIDP from the acute inflammatory demyelinating polyradiculoneuropathy form of Guillain-Barré syndrome. Corticosteroids, intravenous immunoglobulin and plasma exchange each provide short term benefit but the possible long-term benefits of immunosuppressive drugs have yet to be confirmed in randomised, controlled trials.

Neutralization of the chemokine CXCL10 reduces apoptosis and increases axon sprouting after spinal cord injury

Spinal cord injury (SCI) is followed by a secondary degenerative process that includes cell death. We have previously demonstrated that the chemokine CXCL10 is up-regulated following SCI and plays a critical role in T-lymphocyte recruitment to sites of injury and inhibition of angiogenesis; antibody-mediated functional blockade of CXCL10 reduced inflammation while enhancing angiogenesis. We hypothesized, based on these findings, that the injury environment established by anti-CXCL10 antibody treatment would support greater survival of neurons and enhance axon sprouting compared with the untreated, injured spinal cord. Here, we document gene array and histopathological data to support our hypothesis. Gene array analysis of treated and untreated tissue from spinal cord-injured animals revealed eight apoptosis-related genes with significant expression changes at 3 days postinjury. In support of these data, quantification of TUNEL-positive cells at 3 days postinjury indicated a 75% reduction in the number of dying cells in treated animals compared with untreated animals. Gene array analysis of treated and untreated tissue also revealed six central nervous system growth-related genes with significant expression changes in the brainstem at 14 days postinjury. In support of these data, quantification of anterograde-labeled corticospinal tract fibers indicated a 60-70% increase in axon sprouting caudal to the injury site in treated animals compared with untreated animals. These findings indicate that anti-CXCL10 antibody treatment provides an environment that reduces apoptosis and increases axon sprouting following injury to the adult spinal cord.

Alpha-chemokine receptors CXCR1-3 and their ligands in idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of neuromuscular disorders subdivided into polymyositis (PM), sporadic inclusion body myositis (sIBM) and dermatomyositis (DM). Chemokines play an essential role in sustained inflammation associated with IIM. We studied the distribution of the alpha-chemokine receptors CXCR1, 2, 3 and their ligands interferon-gamma (IFN-gamma)-inducible T cell alpha chemoattractant (I-TAC), IFN-gamma-inducible protein of 10 kDa (IP-10), monokine induced by IFN-gamma (MIG) and growth-related oncogene (GRO) in IIM using immunohistochemistry, immunofluorescence and Western blotting. Abundant expression of IP-10 was observed on macrophages and T cells surrounding and invading non-necrotic muscle fibers in PM and sIBM and in T cells in perimysial infiltrates of DM. IP-10 was also localized to blood vessel endothelial cells in all inflammatory and normal muscle tissues. The distribution of other alpha-chemokines was variable: Only low levels of MIG and I-TAC were detected; GRO was localized to the endomysial infiltrates of some PM and sIBM samples, but not in DM. Muscle tissues were invariably CXCR1 negative, while a subset of inflammatory cells in all IIM were CXCR2 positive. Strong CXCR3 expression was observed on the majority of T cells in each IIM. We describe the differential repertoire of alpha-chemokines in IIM, and offer additional proof of the predominance of Th1-driven reactions in the immunopathogenesis of all three diagnostic subgroups. We suggest the Th1-mediated immunity in general, and the CXCR3/IP-10 interaction in particular, as potential targets for novel therapeutic intervention in IIM.

Characterization of cytokine/chemokine profiles of severe acute respiratory syndrome

RATIONALE

There is currently no optimal treatment or effective drug for severe acute respiratory syndrome (SARS), because the immunopathologic mechanism is poorly understood.

OBJECTIVES

To explore the immune mechanism underlying the pathogenesis of SARS, we studied the expression profile of cytokines/chemokines in the blood and the immunopathology of the lung and lymphoid tissues.

METHODS

Fourteen cytokines/chemokines in the blood of 23 patients with SARS were dynamically screened, using a bead-based multiassay system. Reverse transcription-polymerase chain reaction was performed to amplify mRNA. Histopathology of the lung and lymphoid tissues at autopsy was examined, using methods of immunohistochemistry and double immunofluorescence staining.

MAIN RESULTS

Interferon-inducible protein-10 (IP-10) was markedly elevated in the blood during the early stage of SARS, and remained at a high level until convalescence. Moreover, IP-10 was highly expressed in both lung and lymphoid tissues, where monocyte-macrophage infiltration and depletion of lymphocytes were observed. The levels of interleukin-6, interleukin-8, and monocyte chemoattractant protein-1 were concomitantly increased in the blood of the patients with superinfection, and the mRNAs for these cytokines were also increased in lung tissues.

CONCLUSIONS

Induction of IP-10 is a critical event in the initiation of immune-mediated acute lung injury and lymphocyte apoptosis during the development of SARS. Superinfection after the immune injury is the main cause of death. The prompt elevation of interleukin-6, interleukin-8, and monocyte chemoattractant protein-1 is a sign of superinfection, indicating a high risk of death.

Exacerbation of chronic inflammatory demyelinating polyradiculoneuropathy during interferonbeta-1b therapy in a patient with childhood-onset multiple sclerosis

Interferonbeta-1b (IFNbeta-1b) is commonly used for relapsing-remitting multiple sclerosis (MS). We report a 23-year-old woman with childhood onset relapsing-remitting MS treated with IFNbeta-1b who developed overt chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) immediately after therapy. A baseline conduction study before IFNbeta-1b therapy revealed decreased motor conduction velocities and prolonged F wave latencies in several nerves, but there was no neurological sign indicating neuropathy. The existence of subclinical demyelinating neuropathy before IFNbeta-1b treatment was suggested, although the clinical criteria for CIDP were unfulfilled. Following two months of IFNbeta-1b therapy, numbness of her right upper and lower limbs progressively worsened and all tendon reflexes were depressed. Electrophysiologically, F waves were not evoked in any limbs except for the left ulnar and tibial nerves, which showed marked prolongation of F wave latencies. Moreover, subclinical hyperthyroidism developed in association with high titers of anti-thyroglobulin and antithyroid peroxydase antibodies, which were negative before IFNbeta-1b therapy. These findings indicated that peripheral demyelination worsened at the nerve roots after IFNbeta-1b therapy. In addition to the development of autoimmune thyroid disease, the patient now fulfilled the criteria for probable CIDP. Along with the results of a previous report demonstrating IFNbeta-induced CIDP development in patients with childhood MS, this case underscores IFNbeta as a potential risk factor for CIDP in patients with childhood onset MS.

Th1 shift in CIDP versus Th2 shift in vasculitic neuropathy in CSF

To investigate the intra- and extracellular levels of various cytokines and chemokines in CSF in chronic inflammatory demyelinating polyneuropathy (CIDP) and vasculitic neuropathy (VN), 16 cytokines, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12 (p70), IL-13, IL-17, IFN-gamma, TNF-alpha, G-CSF, MCP-1 and MIP-1beta, were measured in CSF supernatant by a multiplexed fluorescent bead-based immunoassay and intracellular production of IFN-gamma and IL-4 in CSF CD4+ T cells were simultaneously measured by flow cytometry in 14 patients with CIDP, 8 patients with VN and 25 patients with other noninflammatory neurologic diseases (OND). In the CSF supernatant, a significant increase of IL-17, IL-8 and IL-6, and a significant decrease of IL-4, IL-5 and IL-7 levels were detected in pretreated CIDP as compared with OND. A significant increase of IL-6, IL-8 and IL-10 levels was found in pretreated VN. Both IL-17 and IL-8 levels correlated strongly with CSF protein levels in CIDP, although the correlation of IL-6 levels was weak. In CSF CD4+ T cells, IFN-gamma+ IL-4- cell percentages were markedly elevated in CIDP compared with OND, but not in VN, resulting in a significant increase of intracellular IFN-gamma/IL-4 ratio in CIDP, even in the absence of CSF pleocytosis. The nonresponders to intravenous immunoglobulins (IVIGs) showed a significantly lower IFN-gamma- IL-4+ CD4+ T cell percentage, and tended to have a higher intracellular IFN-gamma/IL-4 ratio than the responders in CSF. Marked upregulation of Th1 cytokine, IL-17, and downregulation of Th2 cytokines, together with infiltration of IFN-gamma-producing CD4+ T cells are useful markers for CIDP, while several Th2 cytokines are upregulated in VN in CSF.

Acute exposure to CXC chemokine ligand 10, but not its chronic astroglial production, alters synaptic plasticity in mouse hippocampal slices

Brain levels of CXC chemokine ligand 10 (CXCL10) are elevated in a number of neuropathological conditions. To determine its impact on neuronal function, we measured synaptic transmission and plasticity in hippocampal slices prepared from transgenic (TG) mice with chronic astroglial production of CXCL10. We also tested the acute effect of recombinant CXCL10 applied to slices from normal C57Bl/6J mice, CXCL10 TG mice and CXCR3 knock out (KO) mice. Chronic production of CXCL10 did not alter synaptic plasticity. By contrast, exogenous CXCL10 (10 ng/ml) significantly inhibited long-term potentiation (LTP) in slices from normal C57Bl/6J mice and CXCL10 TG. The effect was probably receptor-mediated because CXCL10-induced inhibition of LTP was not observed in CXCR3 KO mice. Our findings suggest that acute exposure to CXCL10 alters synaptic plasticity via CXCR3 in mouse hippocampus.

CXCR3 marks CD4+ memory T lymphocytes that are competent to migrate across a human brain microvascular endothelial cell layer

Chemokines and their receptors may be implicated in leukocyte ingress into brain during inflammation observed during the course of multiple sclerosis (MS). To address receptor modulation on CD4+ memory T lymphocytes during diapedesis, we used an in vitro model of the blood-brain barrier (BBB). We found that only memory (CD45RO+) cells transmigrated and type 3 CXC chemokine receptor (CXCR3) was enriched on transmigrated cells. CXCR3 depletion of the input population did not affect transmigration capability. CXCR3 reemerged on CXCR3 depleted cells independently of endothelial cell exposure, but was susceptible to incubation at 4 degrees C, indicating receptor recycling. We propose that CXCR3 serves as a surface marker for cells that have the capacity to cross the BBB, but does not play an essential role in extravasation.

CCR5 deficiency does not prevent P0 peptide 180–199 immunized mice from experimental autoimmune neuritis

Experimental autoimmune neuritis (EAN) is an inflammatory autoimmune demyelinating disease of peripheral nervous system (PNS) and represents an animal model of Guillain-Barré syndrome (GBS) in man. The inflammatory cell infiltrating into the PNS is a prerequisite for developing EAN. To explore the role of CC chemokine receptor 5 (CCR5) in the inflammatory process of EAN, we induced EAN in CCR5-deficient (CCR5(-/-)) mice with P0 protein peptide 180-199. We found that CCR5(-/-) mice showed a similar EAN clinical course and severity as well as profile of infiltrating macrophages and T cells in cauda equina (CE) of EAN and the same levels of spleen mononuclear cell (MNC) response to antigen and mitogen when compared with CCR5(+/+) control mice. However, increased IP-10 and MIP-1beta production in sciatic nerves were seen in CCR5(-/-) mice. These results suggest that CCR5 deficiency does not prevent P0 peptide 180-199-immunized mice from EAN. Increased MIP-1beta and IP-10 in sciatic nerves may compensate the CCR5 deficiency and contribute to inflammatory cells infiltrating to the PNS.

Advances in understanding and treatment of immune-mediated disorders of the peripheral nervous system

During recent years, novel insights in basic immunology and advances in biotechnology have contributed to an increased understanding of the pathogenetic mechanisms of immune-mediated disorders of the peripheral nervous system. This increased knowledge has an impact on the management of patients with this class of disorders. Current advances are outlined and their implication for therapeutic approaches addressed. As a prototypic immune-mediated neuropathy, special emphasis is placed on the pathogenesis and treatment of the Guillain-Barré syndrome and its variants. Moreover, neuropathies of the chronic inflammatory demyelinating, multifocal motor, and nonsystemic vasculitic types are discussed. This review summarizes recent progress with currently available therapies and--on the basis of present immunopathogenetic concepts--outlines future treatment strategies.

Increased serum levels of interferon-gamma-inducible protein 10 and monokine induced by gamma interferon in patients with haemophagocytic lymphohistiocytosis

We measured serum interferon-gamma-inducible protein 10 (IP-10) and monokine induced by gamma interferon (MIG) levels to investigate the role of these molecules in the pathophysiology of haemophagocytic lymphohistiocytosis (HLH). Serum IP-10 and MIG levels were significantly increased in patients with active HLH compared with those of healthy controls. Serum MIG levels decreased gradually during the course of disease in a patient who recovered without therapy. On the other hand, rapid reduction of MIG and IP-10 levels was observed after chemotherapy in a patient with severe HLH. IP-10 and MIG mRNA expression was enhanced in liver and spleen, and IP-10 mRNA expression was enhanced in bone marrow in the patients, suggesting activated macrophages that infiltrated in these organs as one of the main producers of these cytokines. Serum IP-10 and MIG levels showed a significant correlation with serum IFN-gamma levels. In addition, these chemokines had a significant correlation with fever and serum LDH levels, which are clinical indicators of disease activity of HLH. These results suggest that IP-10 and MIG which are produced by activated macrophages by the stimulation of IFN-gamma, play an important role in the pathophysiology of HLH, by recruitment of activated Th1 cells into the tissues or organs.

Aberrated levels of cerebrospinal fluid chemokines in Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy

Infiltration of spinal nerve roots and peripheral nerves by macrophages and T cells are rather consistent immunopathologic findings in patients with Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Chemokines play a central role in recruitment of leukocytes to inflamed tissue. Chemokines have been implicated in the pathogenesis of the experimental autoimmune neuritis (EAN), which represents an animal model of GBS, but the role of chemokines in GBS and CIDP is not clear. Since chemokines may be released into CSF from inflamed spinal nerve roots, we studied the concentrations of the chemokines MCP-1, MIP-1beta, MIP-3beta, IP-10, SDF-1alpha, RANTES, and SLC in the CSF by sandwich ELISA in patients over the course of GBS and CIDP, before and after immunomodulatory treatment. Controls consisted of patients with noninflammatory neurological disorders. Patients examined in the acute phase of GBS prior to treatment with intravenous high dose immunoglobulins (IvIg) had elevated CSF levels of MCP-1 (a chemoattractant for blood monocytes and dendritic cells) and IP-10 (a chemoattractant for T cells). Patients with CIDP examined prior to immunomodulatory treatment had elevated CSF levels of MIP-3beta (a chemoattractant for mature dendritic cells, naïve and recently activated T cells) and IP-10. Levels of MIP-3beta tended to decreased during follow-up in those CIDP patients responding favorably to immunomodulatory treatment. CSF levels of MCP-1 and IP-10 correlated with the CSF:plasma albumin ratio in both GBS and CIDP patients. In CIDP patients, CSF levels of MIP-3beta also correlated with the CSF:plasma albumin ratio. These data implicate MCP-1 and IP-10 in the pathogenesis of GBS, and IP-10 and MIP-3beta in the pathogenesis of CIDP.

Longitudinal study of chemokine receptor expression on peripheral lymphocytes in multiple sclerosis: CXCR3 upregulation is associated with relapse

The interaction between chemokines and their receptors leads to selective recruitment of cells to foci of inflammation. Cross-sectional studies have reported significantly different expression of chemokine receptors CXCR3, CCR5 and CCR2 on peripheral blood lymphocytes in multiple sclerosis (MS) compared with controls. Cells expressing these receptors are likely to play a pathogenic role as suggested by studies of experimental autoimmune encephalomyelitis. Also, immunogenetic studies of nonfunctional CCR5 receptors in MS patients, due to 32delta deletion, demonstrated a delay in time to next relapse. The aims of this study were to detect any changes in the serial expression of chemokine receptors CCR2, CCR3, CCR5 and CXCR3 on peripheral blood CD4+ lymphocytes from patients with MS and to correlate the changes with relapses. Upregulation of CXCR3 expression on peripheral blood CD4+ lymphocytes was associated with all relapses and CCR5 expression was significantly affected with all relapses. Clinical recovery, with or without intravenous methylprednisolone treatment, coincided with the return of CXCR3 towards baseline in all but one case. Fluctuation in the expression of CXCR3 and CCR5 was also significantly greater in clinically stable patients with MS compared with controls, which may be due to subclinical disease activity. These findings provide further support for the view that CXCR3 and CCR5 antagonists could have a therapeutic value in MS.

IL-1beta and IFN-gamma induce the expression of diverse chemokines and IL-15 in human and rat pancreatic islet cells, and in islets from pre-diabetic NOD mice

AIMS/HYPOTHESIS

Cytokines and chemokines are important mediators of immune responses due to their ability to recruit and activate leukocytes. Using microarray analysis we observed that rat beta cells exposed to IL-1beta and IFN-gamma have increased mRNA levels of chemokines and IL-15. The aim of this study was to characterize the expression of IP-10, MIP-3alpha, fractalkine and IL-15 in rat beta cells, human pancreatic islets, and in islets isolated from NOD mice, both during the pre-diabetic period and following islet transplantation.

METHODS

FACS-purified rat beta cells and human islets were cultured with IL-1beta, IFN-gamma and/or TNF-alpha. Islets were isolated from NOD or BALB/c mice at different ages. For syngeneic islet transplantation, 2- or 3-week-old NOD islets were grafted under the kidney capsule of spontaneously diabetic NOD recipients. Chemokine and IL-15 mRNA expression and protein release were evaluated, respectively, by RT-PCR and ELISA.

RESULTS

Human islets and rat beta cells express IP-10, MIP-3alpha, fractalkine and IL-15 mRNAs upon exposure to cytokines. The expression of IL-15, IP-10 and fractalkine is regulated by IFN-gamma, while the expression of MIP-3alpha is IL-1beta-dependent. Moreover, cytokines induced IL-15, IP-10, Mig, I-TAC and MIP-3alpha protein accumulation in culture medium from human islets. In vivo, there was an age-related increase in IL-15, IP-10 and MIP-3alpha expression in islets isolated from NOD mice. Following syngeneic islet transplantation, increased expression of IL-1beta, IFN-gamma, fractalkine, IP-10, MCP-1 and MIP-3alpha mRNAs were observed in the grafts.

CONCLUSION/INTERPRETATION

Cytokine-exposed islets or beta cells express chemokines and IL-15. This could contribute to the recruitment and activation of mononuclear cells and development of insulitis in early Type 1 diabetes and during graft destruction.

Monocyte chemoattractant protein 1 and chemokine receptor CCR2 productions in Guillain-Barré syndrome and experimental autoimmune neuritis

Infiltration of activated lymphocytes and monocytes is a key phenomenon in the pathogenesis of Guillain-Barré syndrome (GBS) and experimental autoimmune neuritis (EAN). To investigate the role of chemokines, we determined the blood and nerve tissue expression of monocyte chemoattractant protein 1 (MCP-1), a major chemoattractant of monocytes and activated lymphocytes, and its receptor CCR2 in GBS and EAN. MCP-1 circulating levels (ng/ml) in GBS were increased at the time of progression, peaked at the time of plateau and normalized with recovery. MCP-1 circulating levels were the highest in the most disabled patients. The number of circulating CCR2 positive cells was lower in patients with GBS than in healthy subjects (p<0.004). In GBS, MCP-1 expression was observed in epineurial and endoneurial vessels, on infiltrating cells, Schwann cells and in the endoneurial extracellular matrix. Some CCR2 positive cells were observed in nerve biopsies of GBS patients. In EAN, a slight positivity for MCP-1 was observed in the sciatic nerve. There was no circulating CCR2 positive cells. However, at the time of plateau, a conspicuous infiltration of CCR2 positive cells was observed in the sciatic nerve that was no longer observed at the time of recovery. These results suggest that MCP-1 and CCR2 may participate to the recruitment of circulating mononuclear cells in nerve tissue in EAN and GBS.