Monocyte-derived IL12, CD86 (B7-2) and CD40L expression in relapsing and progressive multiple sclerosis

Genetics of immune response to Epstein-Barr virus: prospects for multiple sclerosis pathogenesis

Epstein-Barr virus (EBV) infection has been advocated as a prerequisite for developing multiple sclerosis (MS) and possibly the propagation of the disease. However, the precise mechanisms for such influences are still unclear. A large-scale study investigating the host genetics of EBV serology and related clinical manifestations, such as infectious mononucleosis (IM), may help us better understand the role of EBV in MS pathogenesis. This study evaluates the host genetic factors that influence serological response against EBV and history of IM and cross-evaluates them with MS risk and genetic susceptibility in the Swedish population. Plasma IgG antibody levels against EBV nuclear antigen-1 [EBNA-1, truncated = amino acids (aa) (325-641), peptide = aa(385-420)] and viral capsid antigen p18 (VCAp18) were measured using bead-based multiplex serology for 8744 MS cases and 7229 population-matched control subjects. The MS risk association for high/low EBV antibody levels and history of IM was compared to relevant clinical measures along with sex, age at sampling, and associated HLA allele variants. Genome-wide and HLA allele association analyses were also performed to identify genetic risk factors for EBV antibody response and IM history. Higher antibody levels against VCAp18 [odds ratio (OR) = 1.74, 95% confidence interval (CI) = 1.60-1.88] and EBNA-1, particularly the peptide (OR = 3.13, 95% CI = 2.93-3.35), were associated with an increased risk for MS. The risk increased with higher anti-EBNA-1 IgG levels up to 12× the reference risk. We also identified several independent HLA haplotypes associated with EBV serology overlapping with known MS risk alleles (e.g. DRB1*15:01). Although there were several candidates, no variants outside the HLA region reached genome-wide significance. Cumulative HLA risk for anti-EBNA-1 IgG levels, particularly the peptide fragment, was strongly associated with MS. In contrast, the genetic risk for high anti-VCAp18 IgG levels was not as strongly associated with MS risk. IM history was not associated with class II HLA genes but negatively associated with A*02:01, which is protective against MS. Our findings emphasize that the risk association between anti-EBNA-1 IgG levels and MS may be partly due to overlapping HLA associations. Additionally, the increasing MS risk with increasing anti-EBNA-1 levels would be consistent with a pathogenic role of the EBNA-1 immune response, perhaps through molecular mimicry. Given that high anti-EBNA-1 antibodies may reflect a poorly controlled T-cell defence against the virus, our findings would be consistent with DRB1*15:01 being a poor class II antigen in the immune defence against EBV. Last, the difference in genetic control of IM supports the independent roles of EBNA-1 and IM in MS susceptibility.

cis-B7:CD28 interactions at invaginated synaptic membranes provide CD28 co-stimulation and promote CD8+ T cell function and anti-tumor immunity

B7 ligands (CD80 and CD86), expressed by professional antigen-presenting cells (APCs), activate the main co-stimulatory receptor CD28 on T cells in trans. However, in peripheral tissues, APCs expressing B7 ligands are relatively scarce. This raises the questions of whether and how CD28 co-stimulation occurs in peripheral tissues. Here, we report that CD8+ T cells displayed B7 ligands that interacted with CD28 in cis at membrane invaginations of the immunological synapse as a result of membrane remodeling driven by phosphoinositide-3-kinase (PI3K) and sorting-nexin-9 (SNX9). cis-B7:CD28 interactions triggered CD28 signaling through protein kinase C theta (PKCθ) and promoted CD8+ T cell survival, migration, and cytokine production. In mouse tumor models, loss of T cell-intrinsic cis-B7:CD28 interactions decreased intratumoral T cells and accelerated tumor growth. Thus, B7 ligands on CD8+ T cells can evoke cell-autonomous CD28 co-stimulation in cis in peripheral tissues, suggesting cis-signaling as a general mechanism for boosting T cell functionality.

Gene-environment interactions increase the risk of pediatric-onset multiple sclerosis associated with ozone pollution

BACKGROUND

We previously reported a relationship between air pollutants and increased risk of pediatric-onset multiple sclerosis (POMS). Ozone is an air pollutant that may play a role in multiple sclerosis (MS) pathoetiology. CD86 is the only non-HLA gene associated with POMS for which expression on antigen-presenting cells (APCs) is changed in response to ozone exposure.

OBJECTIVES

To examine the association between county-level ozone and POMS, and the interactions between ozone pollution, CD86, and HLA-DRB1*15, the strongest genetic variant associated with POMS.

METHODS

Cases and controls were enrolled in the Environmental and Genetic Risk Factors for Pediatric MS study of the US Network of Pediatric MS Centers. County-level-modeled ozone data were acquired from the CDC's Environmental Tracking Network. Participants were assigned ozone values based on county of residence. Values were categorized into tertiles based on healthy controls. The association between ozone tertiles and having MS was assessed by logistic regression. Interactions between tertiles of ozone level and the GG genotype of the rs928264 (G/A) single nucleotide polymorphism (SNP) within CD86, and the presence of DRB1*15:01 (DRB1*15) on odds of POMS were evaluated. Models were adjusted for age, sex, genetic ancestry, and mother's education. Additive interaction was estimated using relative excess risk due to interaction (RERI) and attributable proportions (APs) of disease were calculated.

RESULTS

A total of 334 POMS cases and 565 controls contributed to the analyses. County-level ozone was associated with increased odds of POMS (odds ratio 2.47, 95% confidence interval (CI): 1.69-3.59 and 1.95, 95% CI: 1.32-2.88 for the upper two tertiles, respectively, compared with the lowest tertile). There was a significant additive interaction between high ozone tertiles and presence of DRB1*15, with a RERI of 2.21 (95% CI: 0.83-3.59) and an AP of 0.56 (95% CI: 0.33-0.79). Additive interaction between high ozone tertiles and the CD86 GG genotype was present, with a RERI of 1.60 (95% CI: 0.14-3.06) and an AP of 0.37 (95% CI: 0.001-0.75) compared to the lowest ozone tertile. AP results indicated that approximately half of the POMS risk in subjects can be attributed to the possible interaction between higher county-level ozone carrying either DRB1*15 or the CD86 GG genotype.

CONCLUSIONS

In addition to the association between high county-level ozone and POMS, we report evidence for additive interactions between higher county-level ozone and DRB1*15 and the CD86 GG genotype. Identifying gene-environment interactions may provide mechanistic insight of biological processes at play in MS susceptibility. Our work suggests a possible role of APCs for county-level ozone-induced POMS risk.

Safety and Immune Effects of Blocking CD40 Ligand in Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Costimulation by CD40 and its ligand CD40L (CD154) is important for the functional differentiation of T cells. Preclinical studies have recognized the importance of this costimulatory interaction in the pathogenesis of experimental models of multiple sclerosis (MS). To determine safety, pharmacokinetics, and immune effect of a humanized monoclonal antibody (mAb) against CD40 ligand (toralizumab/IDEC-131) in patients with relapsing-remitting MS (RRMS).

METHODS

This single-institution open-label dose-escalation study (phase I) enrolled 12 patients with RRMS to receive 4 doses of 1, 5, 10, or 15 mg/kg of humanized αCD40L (toralizumab) IV infusion every other week. Patients were followed up to 18 weeks, annually, and finally at 5 years. In addition to safety and pharmacokinetics, other secondary and exploratory measurements are immune effects, clinical, MRI, laboratory, and neuropsychological evaluations.

RESULTS

Fifteen adverse events, all of mild to moderate severity, were considered to be of possible or of unknown relationship to treatment. No serious adverse events, including thromboembolic events, occurred during the 18-week defined study period. Annual and long-term follow-up at 5 years revealed no delayed toxicity. Pharmacokinetics were nonlinear between the 5 and 10 mg/kg dose groups. The serum half-life of toralizumab was consistent between the dose groups with a mean of 15.3 days (SD = 1.9). Flow cytometry revealed no depletion of lymphocyte subsets. An increase in the CD25+/CD3+ and CD25+/CD4+ ratio and a shift toward an anti-inflammatory cytokine response were seen after treatment.

DISCUSSION

Our study suggests that blocking CD40L is safe and well tolerated in patients with RRMS while increasing CD25 + T cells and anti-inflammatory cytokine profile. These findings support further studies to assess the efficacy of blocking CD40L as a potential treatment of RRMS.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence on the safety, pharmacokinetics, and immune effects of an mAb to CD40L in patients with RRMS.

Effects of probiotic administration on immune responses of children and adolescents with type 1 diabetes to a quadrivalent inactivated influenza vaccine

This study was planned to evaluate whether a 3-month treatment with Lactobacillus rhamnosus GG (LGG) can modify immune system functions in children and adolescents with type 1 diabetes (T1D), leading to an increased immune response to an injectable quadrivalent inactivated influenza vaccine (QIV). A total of 87 pediatric patients with T1D were screened, although 34 patients in the Probiotic group and 30 in the Control group accepted to be vaccinated with QIV and completed the study. Vaccine immunogenicity and safety and the inflammatory cytokine response were studied. Results showed that QIV was immunogenic and safe in T1D pediatric patients and pre-administration of LGG for three months did not substantially modify the QIV humoral immunity. The combination of QIV and LGG reduced inflammatory responses (i.e., IFN-γ, IL17A, IL-17F, IL-6, and TNF-α) from activated PBMCs of pediatric patients with T1D, without dampening the production of seroprotective antibodies. In conclusion, QIV is associated with an adequate immunogenicity in children and adolescents with T1D in presence of a good safety profile. Although a systematic administration of LGG did not result in an improvement of humoral responses to an influenza vaccine, the probiotic did induce important anti-inflammatory effects.

Phenotypic and functional alterations of myeloid-derived suppressor cells during the disease course of multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system involving dysregulated encephalitogenic T cells. Myeloid-derived suppressor cells (MDSCs) have been recognized for their important function in regulating T-cell responses. Recent studies have indicated a role for MDSCs in autoimmune diseases, but their significance in MS is not clear. Here, we assessed the frequencies of CD14⁺ HLA-DR^low monocytic MDSCs (Mo-MDSCs) and CD33⁺ CD15⁺ CD11b⁺ HLA-DR^low granulocytic MDSCs (Gr-MDSCs) and investigated phenotypic and functional differences of Mo-MDSCs at different clinical stages of MS and in healthy subjects (HC). Increased frequencies of Mo-MDSCs (P < 0.05) and Gr-MDSCs (P < 0.05) were observed in relapsing-remitting MS patients during relapse (RRMS-relapse) compared to stable RRMS (RRMS-rem). Secondary progressive MS (SPMS) patients displayed a decreased frequency of Mo-MDSCs and Gr-MDSCs compared to HC (P < 0.05). Mo-MDSCs within RRMS patients expressed significantly higher cell surface protein levels of CD86 and CD163 compared to SPMS patients. Mo-MDSCs within SPMS exhibited decreased mRNA expression of interleukin-10 and heme oxygenase 1 compared to RRMS and HC. Analysis of T-cell regulatory function of Mo-MDSCs demonstrated T-cell suppressive capacity in RRMS and HCs, while Mo-MDSCs of SPMS promoted autologous T-cell proliferation, which aligned with a differential cytokine profile compared to RRMS and HCs. This study is the first to show phenotypic and functional shifts of MDSCs between clinical stages of MS, suggesting a role for MDSCs as a therapeutic target to prevent MS disease progression.

GM-CSF Promotes Chronic Disability in Experimental Autoimmune Encephalomyelitis by Altering the Composition of Central Nervous System-Infiltrating Cells, but Is Dispensable for Disease Induction

GM-CSF has been portrayed as a critical cytokine in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and, ostensibly, in multiple sclerosis. C57BL/6 mice deficient in GM-CSF are resistant to EAE induced by immunization with myelin oligodendrocyte glycoprotein (MOG)_35-55 The mechanism of action of GM-CSF in EAE is poorly understood. In this study, we show that GM-CSF augments the accumulation of MOG_35-55-specific T cells in the skin draining lymph nodes of primed mice, but it is not required for the development of encephalitogenic T cells. Abrogation of GM-CSF receptor signaling in adoptive transfer recipients of MOG_35-55-specific T cells did not alter the incidence of EAE or the trajectory of its initial clinical course, but it limited the extent of chronic CNS tissue damage and neurologic disability. The attenuated clinical course was associated with a relative dearth of MOG_35-55-specific T cells, myeloid dendritic cells, and neutrophils, as well as an abundance of B cells, within CNS infiltrates. Our data indicate that GM-CSF drives chronic tissue damage and disability in EAE via pleiotropic pathways, but it is dispensable during early lesion formation and the onset of neurologic deficits.

The CD40-CD40L Dyad in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

The CD40-CD40L dyad is an immune checkpoint regulator that promotes both innate and adaptive immune responses and has therefore an essential role in the development of inflammatory diseases, including multiple sclerosis (MS). In MS, CD40 and CD40L are expressed on immune cells present in blood and lymphoid organs, affected resident central nervous system (CNS) cells, and inflammatory cells that have infiltrated the CNS. CD40-CD40L interactions fuel the inflammatory response underlying MS, and both genetic deficiency and antibody-mediated inhibition of the CD40-CD40L dyad reduce disease severity in experimental autoimmune encephalomyelitis (EAE). Both proteins are therefore attractive therapeutic candidates to modulate aberrant inflammatory responses in MS. Here, we discuss the genetic, experimental and clinical studies on the role of CD40 and CD40L interactions in EAE and MS and we explore novel approaches to therapeutically target this dyad to combat neuroinflammatory diseases.

Increased frequency of IL-6-producing non-classical monocytes in neuromyelitis optica spectrum disorder

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system that preferentially affects the optic nerves, spinal cord, and area postrema. A series of evidence suggested that B cells play a fundamental role in the pathogenesis of NMOSD. However, there are still gaps left to be answered in NMOSD pathogenesis suggesting the roles of other immune cells. This study aimed to investigate the monocyte inflammatory characteristics, monocyte subset frequency and cytokine production, and cell-surface molecule expression in NMOSD, multiple sclerosis (MS), and healthy controls (HC).

METHODS

Peripheral blood mononuclear cells of 20 aquaporin 4IgG-positive NMOSD patients, 20 MS patients, and 20 healthy controls were collected to analyze the monocyte subsets and to purify monocytes. To mimic the adaptive immunity, we have activated the monocytes using CD40L and IFN-γ to observe the production of cytokines and expression of cell-surface molecules.

RESULTS

NMOSD monocytes showed a remarkable increase in the production of pro-inflammatory cytokines (IL-6, IL-1β) and increased expression of cell-surface molecules (CD80, HLA, ICAM-1, CD16), as well as a decrease in the levels of anti-inflammatory cytokine IL-10, compared to healthy control (HC) monocytes. As expected, MS monocytes also exhibit increased inflammatory cytokine production and increased cell-surface molecule expression compared to HC monocytes. Further analysis of monocyte subsets revealed that NMOSD monocytes have an increased frequency of the non-classical monocyte subset (CD14⁺CD16⁺⁺) and a decreased frequency of the classical monocyte subset (CD14⁺⁺CD16⁺) compared to HC monocytes. This finding was distinctly different from that of MS monocytes, which had an increased intermediate monocyte (CD14⁺CD16⁺) subset. In addition, these NMOSD non-classical monocyte subsets were highly dedicated, IL-6-producing monocytes.

CONCLUSIONS

Increased expression of cell-surface molecules and a reciprocal dysregulation of inflammatory and anti-inflammatory cytokines in NMOSD monocytes suggest an altered monocyte inflammatory response. CD14⁺CD16⁺⁺ non-classical monocyte subset was more abundant in NMOSD monocytes than in HC or MS monocytes, and NMOSD non-classical monocyte subset had dysregulated IL-6 production, a phenotype which has been reported to be highly associated with NMOSD pathogenesis.

The Role of Dendritic Cell Maturation in the Induction of Insulin-Dependent Diabetes Mellitus

Dendritic cells (DCs) are the dominant class of antigen-presenting cells in humans and are largely responsible for the initiation and guidance of innate and adaptive immune responses involved in maintenance of immunological homeostasis. Immature dendritic cells (iDCs) phagocytize pathogens and toxic proteins and in endosomal vesicles degrade them into small fragments for presentation on major histocompatibility complex (MHC) II receptor molecules to naïve cognate T cells (Th0). In addition to their role in stimulation of immunity, DCs are involved in the induction and maintenance of immune tolerance toward self-antigens. During activation, the iDCs become mature. Maturation begins when the DCs cease taking up antigens and begin to migrate from their location in peripheral tissues to adjacent lymph nodes or the spleen where during their continued maturation the DCs present stored antigens on surface MHCII receptor molecules to naive Th0 cells. During antigen presentation, the DCs upregulate the biosynthesis of costimulatory receptor molecules CD86, CD80, CD83, and CD40 on their plasma membrane. These activated DC receptor molecules bind cognate CD28 receptors presented on the Th0 cell membrane, which triggers DC secretion of IL-12 or IL-10 cytokines resulting in T cell differentiation into pro- or anti-inflammatory T cell subsets. Although basic concepts involved in the process of iDC activation and guidance of Th0 cell differentiation have been previously documented, they are poorly defined. In this review, we detail what is known about the process of DC maturation and its role in the induction of insulin-dependent diabetes mellitus autoimmunity.

Dysregulation of MS risk genes and pathways at distinct stages of disease

Objective:

To perform systematic transcriptomic analysis of multiple sclerosis (MS) risk genes in peripheral blood mononuclear cells (PBMCs) of subjects with distinct MS stages and describe the pathways characterized by dysregulated gene expressions.

Methods:

We monitored gene expression levels in PBMCs from 3 independent cohorts for a total of 297 cases (including clinically isolated syndromes (CIS), relapsing-remitting MS, primary and secondary progressive MS) and 96 healthy controls by distinct microarray platforms and quantitative PCR. Differential expression and pathway analyses for distinct MS stages were defined and validated by literature mining.

Results:

Genes located in the vicinity of MS risk variants displayed altered expression in peripheral blood at distinct stages of MS compared with the healthy population. The frequency of dysregulation was significantly higher than expected in CIS and progressive forms of MS. Pathway analysis for each MS stage–specific gene list showed that dysregulated genes contributed to pathogenic processes with scientific evidence in MS.

Conclusions:

Systematic gene expression analysis in PBMCs highlighted selective dysregulation of MS susceptibility genes playing a role in novel and well-known pathogenic pathways.

CD40 Signaling in Graves Disease Is Mediated Through Canonical and Noncanonical Thyroidal Nuclear Factor κB Activation

CD40, a tumor necrosis factor receptor, is a major immune-modulating susceptibility gene for Graves disease (GD) as well as for a variety of other autoimmune diseases. Its broad association with autoimmunity underscores its paramount role in the development of a normal adaptive immune response, primarily in coordinating effective antigen presentation. The molecular pathways by which CD40 activation in the thyroid induces GD are unknown. In this study, we investigated whether NF-κB, a ubiquitious family of transcription factors, mediates the downstream effects of thyroid-specific CD40 activation. Cultured primary human thyrocytes, from patients with and without GD, underwent CD40 stimulation. Once stimulated, cytokines and transcription factors specific for either the canonical nuclear factor κB (NF-κB)1 pathway [interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α], which primarily recruits cells for innate immunity, or the noncanonical NF-κB2 pathway [B cell-activating factor of the TNF family, CC chemokine ligand (CCL)21], which directs B cell viability, were analyzed. Significant upregulation in the messenger RNA and protein levels of both canonical and noncanonical pathway cytokines was observed. Western blot analyses of the specific transcription factors for the NF-κB1 and NF-κB2 pathways (p65 and p100/p52, respectively) demonstrated that p65 is constitutively expressed. In contrast, CD40 stimulation robustly increased the expression of the NF-κB2 p52 transcription factor, and the upregulation was significantly more profound in the GD tissue than in the normal thyroid tissue. Our data show that CD40 activity in thyrocytes is prominently mediated via NF-κB and furthermore suggest that the NF-κB1 and NF-κB2 pathways both contribute to the triggering and the progression of GD.

An emerging role for eotaxins in neurodegenerative disease

Eotaxins are C-C motif chemokines first identified as potent eosinophil chemoattractants. They facilitate eosinophil recruitment to sites of inflammation in response to parasitic infections as well as allergic and autoimmune diseases such as asthma, atopic dermatitis, and inflammatory bowel disease. The eotaxin family currently includes three members: eotaxin-1 (CCL11), eotaxin-2 (CCL24), and eotaxin-3 (CCL26). Despite having only ~30% sequence homology to one another, each was identified based on its ability to bind the chemokine receptor, CCR3. Beyond their role in innate immunity, recent studies have shown that CCL11 and related molecules may directly contribute to degenerative processes in the central nervous system (CNS). CCL11 levels increase in the plasma and cerebrospinal fluid of both mice and humans as part of normal aging. In mice, these increases are associated with declining neurogenesis and impaired cognition and memory. In humans, elevated plasma levels of CCL11 have been observed in Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, and secondary progressive multiple sclerosis when compared to age-matched, healthy controls. Since CCL11 is capable of crossing the blood-brain barrier of normal mice, it is plausible that eotaxins generated in the periphery may exert physiological and pathological actions in the CNS. Here, we briefly review known functions of eotaxin family members during innate immunity, and then focus on whether and how these molecules might participate in the progression of neurodegenerative diseases.

Update on CD40 and CD154 blockade in transplant models

Generation of an effective immune response against foreign antigens requires two distinct molecular signals: a primary signal provided by the binding of antigen-specific T-cell receptor to peptide-MHC on antigen-presenting cells and a secondary signal delivered via the engagement of costimulatory molecules. Among various costimulatory signaling pathways, the interactions between CD40 and its ligand CD154 have been extensively investigated given their essential roles in the modulation of adaptive immunity. Here, we review current understanding of the role CD40/CD154 costimulation pathway has in alloimmunity, and summarize recent mechanistic and preclinical advances in the evaluation of candidate therapeutic approaches to target this receptor-ligand pair in transplantation.

Immunogenetics of autoimmune thyroid diseases: A comprehensive review

Both environmental and genetic triggers factor into the etiology of autoimmune thyroid disease (AITD), including Graves' disease (GD) and Hashimoto's thyroiditis (HT). Although the exact pathogenesis and causative interaction between environment and genes are unknown, GD and HT share similar immune-mediated mechanisms of disease. They both are characterized by the production of thyroid autoantibodies and by thyroidal lymphocytic infiltration, despite being clinically distinct entities with thyrotoxicosis in GD and hypothyroidism in HT. Family and population studies confirm the strong genetic influence and inheritability in the development of AITD. AITD susceptibility genes can be categorized as either thyroid specific (Tg, TSHR) or immune-modulating (FOXP3, CD25, CD40, CTLA-4, HLA), with HLA-DR3 carrying the highest risk. Of the AITD susceptibility genes, FOXP3 and CD25 play critical roles in the establishment of peripheral tolerance while CD40, CTLA-4, and the HLA genes are pivotal for T lymphocyte activation and antigen presentation. Polymorphisms in these immune-modulating genes, in particular, significantly contribute to the predisposition for GD, HT and, unsurprisingly, other autoimmune diseases. Emerging evidence suggests that single nucleotide polymorphisms (SNPs) in the immunoregulatory genes may functionally hinder the proper development of central and peripheral tolerance and alter T cell interactions with antigen presenting cells (APCs) in the immunological synapse. Thus, susceptibility genes for AITD contribute directly to the key mechanism underlying the development of organ-specific autoimmunity, namely the breakdown in self-tolerance. Here we review the major immune-modulating genes that are associated with AITD and their potential functional effects on thyroidal immune dysregulation.

Stage-specific immune dysregulation in multiple sclerosis

A large body of data indicates that multiple sclerosis (MS) is an autoimmune disease which is initiated by CD4(+) T-helper 1 (Th1) and Th17 cells that are reactive against proteins in the myelin sheath. MS typically begins with a relapsing-remitting course, punctuated by clinical exacerbations associated with the development of focal inflammatory lesions in central nervous system white matter, followed by a secondary progressive (SP) phase, characterized by a gradual accumulation of neurological disability associated with widespread microglial activation and axonal loss. The molecular and cellular basis for this transition is unclear, and the role of inflammation during the SP stage is a subject of active debate. As of now, no immunological biomarkers have been identified in MS that are predictive of the clinical course or therapeutic responsiveness to disease-modifying agents, or that correlate with new lesion development, cumulative lesion load, or degree of disability. The discovery of such biomarkers would greatly facilitate clinical management and provide power for smaller and shorter clinical trials. In this article, we discuss the literature on immunological biomarkers in MS with a focus on stage-specific differences and similarities.

Dysregulation of the IL-23/IL-17 axis and myeloid factors in secondary progressive MS

OBJECTIVE

In the current exploratory study, we longitudinally measured immune parameters in the blood of individuals with relapsing-remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS), and investigated their relationship to disease duration and clinical and radiologic measures of CNS injury.

METHODS

Peripheral blood mononuclear cells (PBMCs) and plasma were obtained from subjects with RRMS, SPMS, and from healthy controls on a monthly basis over the course of 1 year. MRI and Expanded Disability Status Scale evaluations were performed serially. PBMCs were analyzed by enzyme-linked immunosorbent spot assay to enumerate myelin basic protein-specific interleukin (IL)-17- and interferon (IFN)-γ-producing cells. Plasma concentrations of proinflammatory factors were measured using customized Luminex panels.

RESULTS

Frequencies of myelin basic protein-specific IL-17- and IFN-γ-producing PBMCs were higher in individuals with RRMS and SPMS compared to healthy controls. Patients with SPMS expressed elevated levels of IL-17-inducible chemokines that activate and recruit myeloid cells. In the cohort of patients with SPMS without inflammatory activity, upregulation of myeloid-related factors correlated directly with MRI T2 lesion burden and inversely with brain parenchymal tissue volume.

CONCLUSIONS

The results of this exploratory study raise the possibility that Th17 responses and IL-17-inducible myeloid factors are elevated during SPMS compared with RRMS, and correlate with lesion burden. Our data endorse further investigation of Th17- and myeloid-related factors as candidate therapeutic targets in SPMS.

Differential expression of the costimulatory molecules CD86, CD28, CD152 and PD-1 correlates with the host-parasite outcome in leprosy

Leprosy is a spectral disease exhibiting two polar sides, namely, lepromatous leprosy (LL) characterised by impaired T-cell responses and tuberculoid leprosy in which T-cell responses are strong. Proper T-cell activation requires signalling through costimulatory molecules expressed by antigen presenting cells and their ligands on T-cells. We studied the influence of costimulatory molecules on the immune responses of subjects along the leprosy spectrum. The expression of the costimulatory molecules was evaluated in in vitro-stimulated peripheral blood mononuclear cells of lepromatous and tuberculoid patients and healthy exposed individuals (contacts). We show that LL patients have defective monocyte CD86 expression, which likely contributes to the impairment of the antigen presentation process and to patients anergy. Accordingly, CD86 but not CD80 blockade inhibited the lymphoproliferative response to Mycobacterium leprae. Consistent with the LL anergy, there was reduced expression of the positive signalling costimulatory molecules CD28 and CD86 on the T-cells in these patients. In contrast, tuberculoid leprosy patients displayed increased expression of the negative signalling molecules CD152 and programmed death-1 (PD-1), which represents a probable means of modulating an exacerbated immune response and avoiding immunopathology. Notably, the contacts exhibited proper CD86 and CD28 expression but not exacerbated CD152 or PD-1 expression, suggesting that they tend to develop a balanced immunity without requiring immunosuppressive costimulatory signalling.

miR-155 as a multiple sclerosis-relevant regulator of myeloid cell polarization

OBJECTIVE

To define the functional significance of increased miR-155 expression in myeloid cells in multiple sclerosis (MS).

METHODS

miR-155 expression levels were measured in CD14+ monocytes from untreated relapsing-remitting MS patients and compared to healthy controls. Similar microRNA (miRNA) analyses were performed in laser-captured CD68+ cells from perivascular (blood-derived macrophages) and parenchymal (microglia) brain regions in both active MS lesions and noninflammatory cases. Using human adult blood-derived macrophages and brain-derived microglia, in vitro experiments were performed to demonstrate how miR-155 influences the polarization state, phenotype, and functional properties of myeloid cells, in addition to their ability to subsequently impact adaptive T-cell responses.

RESULTS

In MS, miR-155 expression was significantly increased in both peripheral circulating CD14+ monocytes and active lesions (CD68+ cells) compared to control donor monocytes and parenchymal microglia, respectively. In vitro, miR-155 was significantly increased in both M1-polarized primary human macrophages and microglia. Transfection of an miR-155 mimic increased proinflammatory cytokine secretion and costimulatory surface marker expression in both cell types; an miR-155 inhibitor decreased proinflammatory cytokine expression. Coculture experiments demonstrated that allogeneic T-cell responses were significantly enhanced in the presence of miR-155-transfected myeloid cells compared to controls.

INTERPRETATION

Our results demonstrate that miR-155 regulates proinflammatory responses in both blood-derived and central nervous system (CNS)-resident myeloid cells, in addition to impacting subsequent adaptive immune responses. Differential miRNA expression may therefore provide insight into mechanisms responsible for distinct phenotypic and functional properties of myeloid cells, thus impacting their ability to influence CNS injury and repair.

Systemic inflammation in progressive multiple sclerosis involves follicular T-helper, Th17- and activated B-cells and correlates with progression

Pathology studies of progressive multiple sclerosis (MS) indicate a major role of inflammation including Th17-cells and meningeal inflammation with ectopic lymphoid follicles, B-cells and plasma cells, the latter indicating a possible role of the newly identified subset of follicular T-helper (T_FH) cells. Although previous studies reported increased systemic inflammation in progressive MS it remains unclear whether systemic inflammation contributes to disease progression and intrathecal inflammation. This study aimed to investigate systemic inflammation in progressive MS and its relationship with disease progression, using flow cytometry and gene expression analysis of CD4⁺ and CD8⁺T-cells, B-cells, monocytes and dendritic cells. Furthermore, gene expression of cerebrospinal fluid cells was studied. Flow cytometry studies revealed increased frequencies of ICOS⁺T_FH-cells in peripheral blood from relapsing-remitting (RRMS) and secondary progressive (SPMS) MS patients. All MS subtypes had decreased frequencies of Th1 T_FH-cells, while primary progressive (PPMS) MS patients had increased frequency of Th17 T_FH-cells. The Th17-subset, interleukin-23-receptor⁺CD4⁺T-cells, was significantly increased in PPMS and SPMS. In the analysis of B-cells, we found a significant increase of plasmablasts and DC-SIGN⁺ and CD83⁺B-cells in SPMS. ICOS⁺T_FH-cells and DC-SIGN⁺B-cells correlated with disease progression in SPMS patients. Gene expression analysis of peripheral blood cell subsets substantiated the flow cytometry findings by demonstrating increased expression of IL21, IL21R and ICOS in CD4⁺T-cells in progressive MS. Cerebrospinal fluid cells from RRMS and progressive MS (pooled SPMS and PPMS patients) had increased expression of T_FH-cell and plasmablast markers. In conclusion, this study is the first to demonstrate the potential involvement of activated T_FH-cells in MS. The increased frequencies of Th17-cells, activated T_FH- and B-cells parallel findings from pathology studies which, along with the correlation between activated T_FH- and B-cells and disease progression, suggest a pathogenic role of systemic inflammation in progressive MS. These observations may have implications for the treatment of progressive MS.

LTβR and CD40: working together in dendritic cells to optimize immune responses

Generating an immune response tailored to destroy an infecting organism while limiting bystander damage involves guiding T-cell activation using a variety of cues taken from the immunogen (antigen type, dose, and persistence, accompanying danger signals) as well as the host (tissue environment, T-cell frequency, and affinity for antigen). Dendritic cells (DCs) serve as translators of much of this information and are critically required for effective pathogen and tumor clearance. Moreover, dysregulation of DC activation can lead to autoimmunity. Inhibition of the lymphotoxin (LT) and CD40 pathways has been shown to be effective at quieting inflammation in settings where DC-T-cell interactions are key instigators of disease progression. In this review, we compare and contrast the CD40 and LT pathways in the context of receptor/ligand expression, signal transduction, and DC biology. We provide evidence that these two pathways play complementary roles in DC cytokine secretion, thus indirectly shaping the nature of the CD8(+) T-cell response to foreign antigen. Given the distinct role of these pathways in the context of DC function, we propose that dual therapies targeted at both the CD40 and LTβ receptor may have therapeutic potential in silencing DC-driven autoimmunity or in promoting tumor clearance.

Involvement of CD40-CD40 ligand in uncomplicated and refractory celiac disease

OBJECTIVES

Cognate interaction between CD40 on antigen-presenting cells and CD40 ligand (CD40L) on T cells is a crucial costimulatory signal in T-cell activation. In this study, we investigated CD40-CD40L expression in the duodenum of uncomplicated and refractory celiac disease patients, and explored the ex vivo effects of CD40L blockade on cytokine production and the T-helper cell type 1-specific transcription factor T-bet.

METHODS

CD40L and colocalization of CD40 with the dendritic cell markers CD11c and CD123 were investigated by confocal microscopy on tissue sections of duodenal biopsy samples obtained from 14 uncomplicated celiac patients before and after 12 months of gluten-free diet, 5 refractory celiac patients, and 12 controls. CD40 was also analyzed by flow cytometry on single cell suspension of mucosal biopsies. Treated celiac biopsies were stimulated with peptic-tryptic digest of gliadin (PT-gliadin) with or without an anti-CD40L-neutralizing antibody. Interferon (IFN)-γ and interleukin (IL)-17 were measured by ELISA (enzyme-linked immunosorbent assay). T-bet, CD40, and CD40L were determined by immunoblotting.

RESULTS

CD40 and CD40L expression was higher in uncomplicated untreated and refractory celiac patients than in controls; the expression returned to normal after gluten-free diet in uncomplicated patients. Flow cytometric analysis confirmed that most CD40(+) cells were dendritic cells. The addition of the anti-CD40L antibody to treated celiac biopsies significantly inhibited the PT-gliadin-induced production of IFN-γ and IL-17, and mucosal T-bet.

CONCLUSIONS

Our results indicate that the CD40-CD40L pathway has a key role in celiac disease. Disruption of CD40-CD40L interaction may offer a therapeutic alternative in refractory celiac disease.

Constitutive CD40L expression on B cells prematurely terminates germinal center response and leads to augmented plasma cell production in T cell areas

CD40/CD40L engagement is essential to T cell-dependent B cell proliferation and differentiation. However, the precise role of CD40 signaling through cognate T-B interaction in the generation of germinal center and memory B cells is still incompletely understood. To address this issue, a B cell-specific CD40L transgene (CD40LBTg) was introduced into mice with B cell-restricted MHC class II deficiency. Using this mouse model, we show that constitutive CD40L expression on B cells alone could not induce germinal center differentiation of MHC class II-deficient B cells after immunization with T cell-dependent Ag. Thus, some other MHC class II-dependent T cell-derived signals are essential for the generation of germinal center B cells in response to T cell-dependent Ag. In fact, CD40LBTg mice generated a complex Ag-specific IgG1 response, which was greatly enhanced in early, but reduced in late, primary response compared with control mice. We also found that the frequency of Ag-specific germinal center B cells in CD40LBTg mice was abruptly reduced 1 wk after immunization. As a result, the numbers of Ag-specific IgG1 long-lived plasma cells and memory B cells were reduced. By histology, large numbers of Ag-specific plasma cells were found in T cell areas adjacent to Ag-specific germinal centers of CD40LBTg mice, temporarily during the second week of primary response. These results indicate that CD40L expression on B cells prematurely terminated their ongoing germinal center response and produced plasma cells. Our results support the notion that CD40 signaling is an active termination signal for germinal center reaction.

Role of platelets in neuroinflammation: a wide-angle perspective

OBJECTIVES

This review summarizes recent developments in platelet biology relevant to neuroinflammatory disorders. Multiple sclerosis (MS) is taken as the "Poster Child" of these disorders but the implications are wide. The role of platelets in inflammation is well appreciated in the cardiovascular and cancer research communities but appears to be relatively neglected in neurological research.

ORGANIZATION

After a brief introduction to platelets, topics covered include the matrix metalloproteinases, platelet chemokines, cytokines and growth factors, the recent finding of platelet PPAR receptors and Toll-like receptors, complement, bioactive lipids, and other agents/functions likely to be relevant in neuroinflammatory diseases. Each section cites literature linking the topic to areas of active research in MS or other disorders, including especially Alzheimer's disease.

CONCLUSION

The final section summarizes evidence of platelet involvement in MS. The general conclusion is that platelets may be key players in MS and related disorders, and warrant more attention in neurological research.

High-dose cyclophosphamide in the treatment of multiple sclerosis

High dose cyclophosphamide (HDC) has been successfully used for the treatment of a variety of autoimmune diseases. In this study, we sought to determine whether the use of high dose cyclophosphamide provided stabilization of relapsing remitting MS (RRMS), secondary progressive MS (SPMS), or primary progressive MS (PPMS). The parameters evaluated were EDSS scores, lesion load and brain volumes by MRI and frequency of relapses. Twenty-three patients underwent immunoablative therapy with HDC and were followed for 3.5 years. Nine were relapsing remitting (RRMS), 11 secondary progressive (SPMS), and 3 primary progressive (PPMS). Four of 9 RRMS have had no clinical progression up to 3.5 years following treatment. Three of 9 patients maintained a normal neurologic examination with improved EDSS scores. Seven of the nine RRMS patients had reduction in flare frequency which was maintained for 3.5 years following treatment or no immunomodulating agents. Subgroup analysis in the RRMS patients of lesion load and brain parenchymal volume revealed a favorable trend in these parameters which did not reach statistical significance. The treatment was generally ineffective for SPMS and failed in the 2 PPMS patients. HDC was well tolerated, demonstrated a good safety profile and had minimal adverse effects. These results along with previous reports suggest that early use of HDC therapy in RRMS is promising.

1Alpha,25-dihydroxyvitamin D3 inhibits CD40L-induced pro-inflammatory and immunomodulatory activity in human monocytes

CD40 ligand (CD40L) stimulation induces proinflammatory and immunomodulatory activity in monocytes. Here, we report on the effects of the steroid hormone 1alpha,25-dihydroxyvitamin D3 (1,25D3) on human blood monocytes that have been stimulated with the CD40L ligand. Co-treatment of CD40L-stimulated monocytes with 1,25D3 resulted in reduced production and secretion of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, as well as in reduced expression of the surface co-stimulatory molecules CD80 and CD86. In addition, costimulation of CD4+ T lymphocytes by monocytes co-treated with CD40L and 1,25D3 resulted in reduced cell proliferation and diminished interferon (IFN)-gamma but enhanced IL-10 production by CD4+ T cells. Finally, 1,25D3 interfered with the ability of CD40L to rescue monocytes from apoptosis induced by serum withdrawal. These findings suggest that 1,25D3 may regulate the interaction of monocytes with T cells or other cell types that express CD40L, thus influencing the outcome of the immune or inflammatory response.

Expansion of CD4+CD28- T cells producing high levels of interferon-{gamma} in peripheral blood of patients with multiple sclerosis

CD4(+) T cells that lack surface expression of the CD28 co-stimulatory molecule (CD4(+)CD28(-) T cells) were expanded in peripheral blood of patients with multiple sclerosis (MS) [5.20 +/- 1.67% vs 13.00 +/- 2.68% (healthy controls (HC) versus patients with MS)]. Both the CD4(+)CD28(+) and CD4(+)CD28(-) T-cell populations of patients with MS produced higher levels of interferon (IFN)-gamma compared with those in HC. In particular, the proportion of IFN-gamma(+) cells among CD4(+)CD28(-) T cells from patients with MS was considerably high. However, expression of co-stimulatory molecules including inducible costimulator (ICOS), activating natural killer receptors, or members of tumor necrosis factor receptor family that replace CD28 in CD4(+)CD28(-) T cells of patients with MS could not be identified. A unique subpopulation bearing the CD45RA(high)CCR7(-) phenotype was identified among the CD4(+)CD28(-) T cells of some patients with MS. Because only MS samples contained this CD45RA(high)CCR7(-) population attributed to terminally differentiated effector memory cells and lacked naive CD45RA(high)CCR7(+) cells, we suggest that CD4(+)CD28(-) T cells of patients with MS represent a cell population which is in more differentiated state than healthy subjects. In patients treated with IFN-beta-1b, IFN-gamma production from CD4(+)CD28(+) T cells was suppressed compared with that in untreated patients. On the contrary, in the CD4(+)CD28(-) population, production of IFN-gamma in IFN-beta-1b-treated patients was not significantly suppressed compared with that in untreated patients with MS. Thus, an additional treatment strategy that specifically targets this cell population may enhance the beneficial effect of IFN-beta on MS.

Effects of interferon-β on co-signaling molecules: upregulation of CD40, CD86 and PD-L2 on monocytes in relation to clinical response to interferon-β treatment in patients with multiple sclerosis

Interferon-beta (IFN-β) reduces disease activity in a subgroup of patients with relapsing remitting multiple sclerosis (MS). The mechanism of action as well as the pathophysiological basis of responsiveness to IFN-β is not well understood. Since T-cell activation plays an important part in the pathophysiology of MS, we here investigated the effect of IFN-β on the expression of co-signaling pathways (CD28—CD80/CD86, CD154—CD40, ICOS—ICOSL, PD-1—PD-L1/2) in MS patients and correlated the results with the clinical response to IFN-β in individual patients. Expression of co-signaling molecules was measured by flow cytometry in vitro on peripheral blood mononuclear cells after incubation with IFN-β, and in vivo in whole blood samples of 32 untreated and 24 IFN-β treated MS patients, including 13 patients longitudinal. IFN-β treatment induced upregulation of CD40, CD80, CD86, PD-L1 and PD-L2 on monocytes as well as PD-L1 on CD4+-T-cells in vitro and in vivo. IFN-β treated MS patients were grouped into responders and non-responders on the basis of Kurtzkés EDSS (expanded disability status scale) progression and relapse rate. Upregulation of CD40, CD86 and PD-L2 on monocytes was associated with treatment response to IFN-β ( P < 0.001, P = 0.028 and P = 0.028, respectively). Our results show that IFN-β upregulates co-stimulatory as well as co-inhibitory molecules in vitro and in vivo implicating that modulation of the balance between positive and negative co-stimulatory signals might be an important part of the mechanism of action of IFN-β in MS. Upregulation of the expression of CD40, CD86 and PD-L2 may be useful as a predictive marker for clinical response to IFN-β treatment at early timepoints during IFN-β therapy. Multiple Sclerosis 2008; 14: 166—176. http://msj.sagepub.com

Increased serum levels of circulating CD40 ligand in patients with bullous pemphigoid: preliminary results

BACKGROUND

Autoimmune bullous diseases are characterized by autoantibodies against specific adhesion molecules of the skin and/or mucous membrane. While these autoantibodies are known to play a primary role in the disease manifestation, it remains unknown how disease-specific autoreactive B cells and autoantibodies are induced. Recent studies have indicated the importance of the CD40 and CD40 ligand (CD40L) receptor-ligand pair in the immunopathogenesis of autoimmune diseases. CD40L circulates in soluble form, and some reports suggest that serum soluble CD40L (sCD40L) levels are increased in various autoimmune diseases.

OBJECTIVES

To determine serum sCD40L levels in patients with pemphigus vulgaris (PV) and bullous pemphigoid (BP), and to determine their correlation with clinical findings and laboratory findings.

PATIENTS AND METHODS

Sera from 10 PV patients, 35 BP patients and 12 normal controls were subjected to ELISA assays to measure serum levels of sCD40L, anti-desmoglein-3 antibody and anti-BP180 antibody.

RESULTS AND CONCLUSIONS

Circulating sCD40L levels were significantly elevated in BP patients, but not in PV patients. Serum sCD40L levels increased in the early stage of disease onset and recurrence in BP patients. In conclusion, circulating sCD40L levels may be a useful marker for early activation of autoimmune diathesis and, furthermore, an effective therapeutic target in patients with BP.

Interferon-beta mediates opposing effects on interferon-gamma-dependent Interleukin-12 p70 secretion by human monocyte-derived dendritic cells

Interferon-beta (IFN-beta) exposure during tumour necrosis factor-alpha (TNF-alpha)-induced human monocyte-derived dendritic cell (DC) maturation augments the capacity of DC to promote the generation of T helper 1 (Th1) cells, while IFN-beta exposure during naive Th cell stimulation inhibits Th1 cell generation (Nagai et al., J Immunol, 2003 171:5233-43). Investigating these contradictory outcomes of IFN-beta exposure, we find that isolated DC matured with both TNF-alpha and IFN-beta secrete more IL-12 p70 upon CD40L stimulation than DC matured with TNF-alpha alone. mAb blocking studies indicate that the basis for this enhanced IL-12 p70 production is augmentation of two successive CD40-dependent autocrine pathways in the DC: (1) a pathway in which low levels of IL-12 p70, IL-27, IL-18 and, possibly, IL-23 act to mediate autocrine induction of DC IFN-gamma secretion; and (2) an IFN-gamma-initiated autocrine pathway promoting optimal DC IL-12 p70 secretion. In contrast to the IL-12 p70 promoting effects of IFN-beta during DC maturation, IFN-beta pre-treatment before CD40L stimulation was found to inhibit IFN-gamma-mediated enhancement of DC IL-12 p70 secretion. Thus, IFN-beta exposure during TNF-alpha-mediated DC maturation may promote Th1 polarization by increasing DC IL-12 p70 secretion, through enhancement of autocrine-acting IFN-gamma production by the DC. Moreover, IFN-beta exposure during naive Th cell stimulation may inhibit Th1 cell generation by blocking the IFN-gamma-induced signals required for optimal CD40L-induced DC IL-12 p70 secretion. IFN-beta pre-treatment was also observed to inhibit CD40L-induced DC IL-23 secretion. Our findings may account for some of the beneficial effects of IFN-beta therapy in patients with relapsing remitting multiple sclerosis.

The role of CD4 T cells in the pathogenesis of multiple sclerosis

T lymphocytes play a central role in the pathogenesis of multiple sclerosis (MS) (Zhang et al., 1992). Both CD4+ and CD8+ T cells have been demonstrated in MS lesions, with CD4+ T cells predominating in acute lesions and CD8+ T cells being observed more frequently in chronic lesions (Raine, 1994). Additionally, T cells are found in all four of the described histopathologic subtypes of MS (Lucchinetti et al., 2000). Activated myelin-reactive CD4+ T cells are present in the blood and cerebrospinal fluid (CSF) of MS patients; in contrast, only nonactivated myelin-reactive T cells are present in the blood of controls (Zhang et al., 1994). The success of several T-cell-targeted therapies in MS reinforces the importance of the role of the T cell in MS pathogenesis. Here, we outline basic concepts in CD4+ T-cell immunology and summarize the current understanding of the role of CD4+ T cells in the pathogenesis of MS.

B cells play a cooperative role via CD40L-CD40 interaction in T cell-mediated experimental autoimmune neuritis in Lewis rats

The expression of co-stimulatory molecules CD40 and CD40L was examined over the course of experimental autoimmune neuritis (EAN) induced in Lewis rats by immunization with bovine peripheral nerve myelin. In draining lymph nodes, highest level of CD40L expression was seen on day 7 post immunization (p.i.), i.e. before onset of clinical signs of EAN, while CD40 expression was increased on day 14 p.i., i.e. at peak of clinical disease. In contrast, both CD40 and CD40L expressing cells in sciatic nerves, a target organ of EAN, peaked on day 14 p.i., large numbers of both expressing cells were mainly detected on day 14-21 p.i. After co-culture with EAN rat B cells bearing CD40, P0 peptide 180-199-specific T cell line cells exhibited a rapid down-regulation of CD40L expression. Furthermore, EAN rats had enhanced P0 peptide 180-199-specific antibody responses on day 14 p.i., which might have contributed to their aggravated EAN and further demonstrated the role of antibodies in EAN. The results indicate that CD40L-CD40 interactions are involved in the initiation of the antigen-specific T cell responses associated with the generation and development of EAN, and may mediate autoantibody production in EAN. Evidently, B cells play a cooperative role via CD40L-CD40 interaction in T cell-mediated EAN of Lewis rats.

Elevated levels of soluble CD40 ligand (sCD40L) in serum of patients with systemic autoimmune diseases

The CD40-CD40L costimulatory pathway is involved in the evolution of many autoimmune diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and Sjögren's syndrome (SS). Increased levels of sCD40L in the serum have been associated with disease activity in SLE. The aim of this study was to investigate the role of sCD40L in the development of lupus nephritis and examine its possible association with cryoglobulinemia in Sjögren's syndrome. We used a 2-site sandwich ELISA to measure the levels of sCD40L in sera, from 64 patients with SLE, RA and SS and 17 healthy blood donors. Biological specimens from the affected tissues such as urine from patients with lupus nephritis and saliva from patients with SS were also tested. In this regard, paired sera and first morning urine samples from 6 SLE patients (3 with active lupus nephritis and 3 with inactive lupus nephritis) were tested with the sCD40L ELISA protocol as well as paired sera and salivary samples from 5 patients with SS and cryoglobulinemia, 5 patients with SS and anti-Ro or anti-La autoantibodies and 5 age-matched healthy control donors. We also examined possible correlations of sCD40L levels with several laboratory and clinical parameters in SS and SLE. We found that sera from SLE and SS patients had significantly higher levels of sCD40L compared to sera from healthy control donors. No sCD40L was detected, in urine samples of patients with either active or inactive nephritis and in salivary samples from SS patients or normal subjects. Soluble CD40L is elevated in sera of SS and SLE patients but further investigation is needed to determine its possible role in SLE nephritis and Sjögren's syndrome.

Effects of sex hormones on costimulatory molecule expression in multiple sclerosis

Sex hormones play a central role as modulators of immune responses and autoimmune diseases. We hypothesized that suppression of MS disease during pregnancy may be mediated by sex steroid hormones via regulation of costimulatory molecules such as CD40L or CD80/CD86 (B7-1/B7-2). We tested two sex hormones that are implicated in immune suppression during pregnancy: estriol and progesterone. We also examined whether this regulation is gender-specific or disease-related. PBMC from untreated relapsing remitting multiple sclerosis (RR MS) patients and controls were examined for expression of T cell and monocyte costimulatory molecules following mitogen stimulation in the presence or absence of sex hormones. In the absence of hormones, we confirmed that mitogen stimulation induced significantly more CD40L on the surface of CD4(+)T cells in MS patients compared to controls, and we extend these findings by showing there were no gender differences in induction of CD40L. Although supra-physiologic doses of hormones mildly suppressed CD40L expression on activated T cells, in vitro exposure to typical pregnancy-related physiologic doses of estriol or progesterone showed very little or no suppression of CD40L. On monocytes, neither estriol nor progesterone significantly altered the expression of CD80/CD86. These results suggest that physiologic doses of estriol or progesterone cannot alter CD40L on T cells or CD80/CD86 on monocytes sufficiently to explain the improvement observed in MS during pregnancy. Thus, although amelioration of MS and other autoimmune diseases during pregnancy is thought to be due to increased sex hormones, the present results do not support a role for suppression of costimulation via estriol or progesterone.

Intergenomic consensus in multifactorial inheritance loci: the case of multiple sclerosis

Genetic linkage and association studies define chromosomal regions, quantitative trait loci (QTLs), which influence the phenotype of polygenic diseases. Here, we describe a global approach to determine intergenomic consensus of those regions in order to fine map QTLs and select particularly promising candidate genes for disease susceptibility or other polygenic traits. Exemplarily, human multiple sclerosis (MS) susceptibility regions were compared for sequence similarity with mouse and rat QTLs in its animal model experimental allergic encephalomyelitis (EAE). The number of intergenomic MS/EAE consensus genes (295) is significantly higher than expected if the animal model was unrelated to the human disease. Hence, this approach contributes to the empirical evaluation of animal models for their applicability to the study of human diseases.

CD40/CD154 interactions at the interface of tolerance and immunity

Development of the acquired immune response is dependent on the signaling of CD40 by its ligand, CD154. These molecules govern both the magnitude and quality of humoral- and cell-mediated immunity. A litany of studies have conclusively documented that blockade of this ligand-receptor pair can prevent, and also intervene in, the progression of antibody- and cell-mediated autoimmune diseases, and can instill long-lived allogeneic and xenogeneic graft tolerance. Many effector mechanisms of inflammation are abolished as a result of CD154 blockade, but we are now beginning to understand that CD154 blockade may, in some instances, engender long-lived, antigen-specific tolerance. In the context of transplantation tolerance, we present a hypothesis that alpha CD154 blockade is most effective at inducing long-lived allospecific tolerance if anergy and regulation can be elicited prior to the onslaught of inflammation that is induced by grafting (preemptive tolerance). This facet of alpha CD154-induced tolerance appears to co-opt the normal processes of peripheral tolerance induced by immature DCs and can be exploited to induce long-lived antigen-specific tolerance. The underlying science and the prospects for inducing long-lived antigen-specific tolerance in a model of allograft tolerance through CD154 blockade are presented and discussed.

Association of common T cell activation gene polymorphisms with multiple sclerosis in Australian patients

Susceptibility to multiple sclerosis (MS) may be influenced by the interaction of several genes within a biological pathway. T cell activation and costimulation may be potentially important in MS pathogenesis. We have therefore investigated associations between MS and polymorphisms in the CD152 (CTLA-4), CD28, CD80 and CD86 genes in Australian patients. We found no significant MS association with CTLA-4 exon 1 +49 alleles, and meta-analysis showed no significant association across nine comparable datasets (OR=1.04, p=0.54), nor with primary progressive MS across seven datasets (OR=1.19, p=0.21). Haplotype analysis showed a trend towards a decrease of the CTLA-4-1722C, -1577G, +49G haplotype in +49 G positive MS patients compared with controls (p=0.06). Screening of CD28, CD80 and CD86 genes identified novel polymorphisms in the putative promoter regions of CD28 (-372 G/A) and CD86 (exon 2 -359 deletionAAG). There was a significant increase of the CD28 -372 G allele frequency in MS patients vs. controls (p=0.045) and a trend towards a significant interaction between this allele and the CTLA-4 +49 G allele (OR=4.00, p=0.058). Our results suggest that the CTLA-4 +49 alone is not associated with overall susceptibility to MS, but may be important in clinical subsets of patients and/or may interact epistatically with other gene polymorphisms.

Role of costimulatory pathways in the pathogenesis of multiple sclerosis and experimental autoimmune encephalomyelitis

Multiple sclerosis is an immune-mediated disorder of the central nervous system. T lymphocytes are thought to play a central role in the initiation and potentially in the propagation of this disease. Two signals are required for T-cell activation. The first signal consists of the interaction of the T-cell receptor with antigen presented by the MHC molecule on antigen-presenting cells. The second signal requires engagement of costimulatory receptors on T cells with their ligands on antigen-presenting cells. Several costimulatory pathways have been shown to play an important role in T-lymphocyte activation. Here we will review the current literature on the contribution of the B7-1/2-CD28/CTLA-4, inducible costimulatory molecule-B7h, programmed death pathway 1-programmed death pathway ligand 1/ligand 2, CD40-CD154, OX40-OX40 ligand, and CD137-CD137 ligand pathways to the pathogenesis of multiple sclerosis and their potential roles as therapeutic targets.

Monocyte-derived cytokines in multiple sclerosis

MS is an inflammatory, presumably autoimmune, disease mediated by the activation of T cells, B cells and monocytes (MO). Inflammation is thought to occur early during the relapsing-remitting phase of MS (RRMS), whereas in the later phases of MS such as secondary progressive MS (SPMS), inflammation tends to diminish. Our objective was to compare the types and amounts of proinflammatory and regulatory cytokines produced by MO from relapsing-remitting patients with or without treatment with IFN-beta (RRMS+ therapy, RRMS- therapy), respectively, from secondary progressive patients (SPMS) and from healthy controls (HC). MO were isolated by a density-gradient technique and three different techniques (RNase protection assay, ELISA and intracellular cytokine staining) were used to assess cytokine levels. An increase in IL6, IL12 and TNF-alpha was observed by all three methods for RRMS- therapy and for SPMS patients compared to HC and RRMS+ therapy patients. We conclude that proinflammatory and regulatory monokines can be derived from MO of MS patients and that these levels are modulated by IFN-beta therapy. Although it is believed that inflammation tends to diminish in SPMS patients, our data show that inflammatory cytokines continue to be released at high levels, suggesting that IFN-beta or IL10 treatment may be beneficial for this group.