Changes in activated T cells in the blood correlate with disease activity in multiple sclerosis

The mosaic of autoimmunity - A taste for more. The 12th international congress of autoimmunity 2021 (AUTO12) virtual

Notwithstanding the fact that the 12th international congress of autoimmunity (AUTO12) was held virtual this year, the number of the abstracts submitted and those presented crossed the thousand marks. Leading investigators and researchers from all over the world presented the latest developments of their research in the domain of autoimmunity and its correlation with various diseases. In terms of mechanisms of autoimmunity, an update on the mechanisms behind the association of autoimmunity with systemic diseases focusing on hyperstimulation was presented during AUTO12. In addition, a new mechanism of ASIA syndrome caused by an intrauterine contraceptive device was revealed demonstrating a complete resolution of symptoms following device removal. In regard to the correlation between autoimmunity and neurogenerative diseases, the loss of structural protein integrity as the trigger of immunological response was shown. Schizophrenia as well, and its correlation to pro-inflammatory cytokines was also addressed. Furthermore, and as it was said AUTO12 virtual due to COVID-19 pandemic, various works were dedicated to SARS-CoV-2 infection and COVID-19 in terms of autoimmune mechanisms involved in the pathogenesis, treatment and complications of COVID-19. For instance, the correlation between autoimmunity and the severity of COVID-19 was viewed. Moreover, the presence and association of autoantibodies in COVID-19 was also demonstrated, as well as the clinical outcomes of COVID-19 in patients with rheumatic diseases. Finally, immune-mediated reactions and processes secondary to SARS-CoV-2 vaccination was displayed. Due to the immense importance of all of the topics addressed and while several hundreds of works were presented which cannot be summed up in one paper, we aimed hereby to highlight some of the outstanding abstracts and presentations during AUTO12.

Central Nervous System-Infiltrating T Lymphocytes in Stroke Are Activated via Their TCR (T-Cell Receptor) but Lack CD25 Expression

[Figure: see text].

PRMT5 Promotes Cyclin E1 and Cell Cycle Progression in CD4 Th1 Cells and Correlates With EAE Severity

Multiple Sclerosis (MS) is a debilitating central nervous system disorder associated with inflammatory T cells. Activation and expansion of inflammatory T cells is thought to be behind MS relapses and influence disease severity. Protein arginine N-methyltransferase 5 (PRMT5) is a T cell activation-induced enzyme that symmetrically dimethylates proteins and promotes T cell proliferation. However, the mechanism behind PRMT5-mediated control of T cell proliferation and whether PRMT5 contributes to diseases severity is unclear. Here, we evaluated the role of PRMT5 on cyclin/cdk pairs and cell cycle progression, as well as PRMT5's link to disease severity in an animal model of relapsing-remitting MS. Treatment of T helper 1 (mTh1) cells with the selective PRMT5 inhibitor, HLCL65, arrested activation-induced T cell proliferation at the G1 stage of the cell cycle, suggesting PRMT5 promotes cell cycle progression in CD4+ T cells. The Cyclin E1/Cdk2 pair promoting G1/S progression was also decreased after PRMT5 inhibition, as was the phosphorylation of retinoblastoma. In the SJL mouse relapsing-remitting model of MS, the highest PRMT5 expression in central nervous system-infiltrating cells corresponded to peak and relapse timepoints. PRMT5 expression also positively correlated with increasing CD4 Th cell composition, disease severity and Cyclin E1 expression. These data indicate that PRMT5 promotes G1/S cell cycle progression and suggest that this effect influences disease severity and/or progression in the animal model of MS. Modulating PRMT5 levels may be useful for controlling T cell expansion in T cell-mediated diseases including MS.

lincR-Ccr2-5′AS and THRIL as potential biomarkers of multiple sclerosis

Background

Multiple sclerosis (MS) is a demyelinating disease affecting the central nervous system (CNS). Long non-coding RNAs (lncRNAs) were believed to play a role in the pathogenesis of neurological disorders including MS. lincR-Ccr2-5′AS is expressed in the T helper2 (Th2) lineage. TNF-α heterogeneous nuclear ribonucleoprotein L (THRIL) causes the induction of TNF-α and regulates innate immune response and inflammation. We investigated the expression of lincR-Ccr2-5′AS and THRIL in MS to clarify their association with MS risk and the clinical features.

Results

LincR-Ccr2-5′AS was significantly downregulated in MS patients (fold change = 0.43±0.29, p = 0.03). The expression level was significantly low in patients with motor weakness and optic neuritis, patients with Expanded Disability Status Scale (EDSS) ≥5.5, and treatment-naïve patients. THRIL was significantly upregulated in MS patients (fold change = 6.18±2, p = 0.02). Its expression was significantly higher in patients with relapsing-remitting multiple sclerosis (RRMS), patients with motor weakness, patients with EDSS ≤5, and patients who received interferon.

Conclusion

Our results showed the downregulation of lincR-Ccr2-5′AS and the upregulation of lncRNA THRIL in MS patients. This differential expression of both lncRNAs may have an important role in MS pathogenesis.

Dipeptidyl peptidase-4 inhibitors and the risks of autoimmune diseases in type 2 diabetes mellitus patients in Taiwan: a nationwide population-based cohort study

AIMS

Dipeptidyl peptidase-4, a transmembrane glycoprotein expressed in various cell types, serves as a co-stimulator molecule to influence immune response. This study aimed to investigate associations between DPP-4 inhibitors and risk of autoimmune disorders in patients with type 2 diabetes mellitus in Taiwan.

METHODS

This retrospective cohort study used the nationwide data from the diabetes subsection of Taiwan National Health Insurance Research Database between January 1, 2009, and December 31, 2013. Cox proportional hazards models were developed to compare the risk of autoimmune disorders and the subgroup analyses between the DPP-4i and DPP-4i-naïve groups.

RESULTS

A total of 774,198 type 2 diabetic patients were identified. The adjusted HR of the incidence for composite autoimmune disorders in DPP-4i group was 0.56 (95% CI 0.53-0.60; P < 0.001). The subgroup analysis demonstrated that the younger patients (aged 20-40 years: HR 0.47, 95% CI 0.35-0.61; aged 41-60 years: HR 0.50, 95% CI 0.46-0.55; aged 61-80 years: HR 0.63, 95% CI 0.58-0.68, P = 0.0004) and the lesser duration of diabetes diagnosed (0-5 years: HR 0.48, 95% CI 0.44-0.52; 6-10 years: HR 0.48, 95% CI 0.43-0.53; ≧ 10 years: HR 0.86, 95% CI 0.78-0.96, P < 0.0001), the more significant the inverse association of DPP-4 inhibitors with the incidence of composite autoimmune diseases.

CONCLUSIONS

DPP-4 inhibitors are associated with lower risk of autoimmune disorders in type 2 diabetes mellitus patients in Taiwan, especially for the younger patients and the lesser duration of diabetes diagnosed. The significant difference was found between the four types of DPP-4 inhibitors and the risk of autoimmune diseases. This study provides clinicians with useful information regarding the use of DPP-4 inhibitors for treating diabetic patients.

Target identification among known drugs by deep learning from heterogeneous networks

Without foreknowledge of the complete drug target information, development of promising and affordable approaches for effective treatment of human diseases is challenging. Here, we develop deepDTnet, a deep learning methodology for new target identification and drug repurposing in a heterogeneous drug-gene-disease network embedding 15 types of chemical, genomic, phenotypic, and cellular network profiles. Trained on 732 U.S. Food and Drug Administration-approved small molecule drugs, deepDTnet shows high accuracy (the area under the receiver operating characteristic curve = 0.963) in identifying novel molecular targets for known drugs, outperforming previously published state-of-the-art methodologies. We then experimentally validate that deepDTnet-predicted topotecan (an approved topoisomerase inhibitor) is a new, direct inhibitor (IC50 = 0.43 μM) of human retinoic-acid-receptor-related orphan receptor-gamma t (ROR-γt). Furthermore, by specifically targeting ROR-γt, topotecan reveals a potential therapeutic effect in a mouse model of multiple sclerosis. In summary, deepDTnet offers a powerful network-based deep learning methodology for target identification to accelerate drug repurposing and minimize the translational gap in drug development.

FOXO1 transcription factor plays a key role in T cell-HIV-1 interaction

HIV-1 is dependent on the host cell for providing the metabolic resources for completion of its viral replication cycle. Thus, HIV-1 replicates efficiently only in activated CD4⁺ T cells. Barriers preventing HIV-1 replication in resting CD4⁺ T cells include a block that limits reverse transcription and also the lack of activity of several inducible transcription factors, such as NF-κB and NFAT. Because FOXO1 is a master regulator of T cell functions, we studied the effect of its inhibition on T cell/HIV-1 interactions. By using AS1842856, a FOXO1 pharmacologic inhibitor, we observe that FOXO1 inhibition induces a metabolic activation of T cells with a G0/G1 transition in the absence of any stimulatory signal. One parallel outcome of this change is the inhibition of the activity of the HIV restriction factor SAMHD1 and the activation of the NFAT pathway. FOXO1 inhibition by AS1842856 makes resting T cells permissive to HIV-1 infection. In addition, we found that FOXO1 inhibition by either AS1842856 treatment or upon FOXO1 knockdown induces the reactivation of HIV-1 latent proviruses in T cells. We conclude that FOXO1 has a central role in the HIV-1/T cell interaction and that inhibiting FOXO1 with drugs such as AS1842856 may be a new therapeutic shock-and-kill strategy to eliminate the HIV-1 reservoir in human T cells.

HIV-1 is controlled by host restriction factors that interfere with its life cycle. However, the virus has equipped itself to counter these strategies. We report a new interplay between HIV-1 and human T lymphocytes through the FOXO1 transcription factor. By using AS1842856, a drug targeting FOXO1, we found that FOXO1 inhibition triggers metabolic activation and G₀/G₁ transition of resting T cells and also by the inactivation of the SAMHD1 viral restriction factor. FOXO1 inhibition makes resting CD4⁺ T cells permissive to HIV-1 infection. We finally found that pharmacologic (AS1842856 treatment) or genetic (shRNA) silencing of FOXO1 reactivate HIV-1 latent proviruses. Thus FOXO1 appears as an important player of the HIV-1/T-cell relationship and a new potential therapeutic target for intervention during HIV-1 infection.

Is there an association between dipeptidyl peptidase-4 inhibitors and autoimmune disease? A population-based study

The association of dipeptidyl peptidase-4 inhibitors (DPP4is) with autoimmune diseases is controversial. While these agents were proposed as a novel therapeutic approach for several inflammatory diseases by blocking T cell proliferation and cytokine production, they were found to trigger inflammatroy bowel disease, inflammatory arthritis and bullous pemphigoid. Our objective is to examine the association between DPP4i and autoimmune diseases. This study was conducted as a cross-sectional study utilizing the database of Clalit Health Services. The prevalence of 15 autoimmune-/immune-mediated diseases was compared between patients on DPP4i treatment and age-, sex-, and ethnicity-matched controls. Univariate analysis was performed using chi-square and the Student t test and multivariate analysis was performed using a logistic regression model. The study included 283 patients treated with DPP4i agents and 5660 age-, sex-, and ethnicity-matched diabetic control subjects. The prevalence of Crohn's disease (1.1 vs. 0.3%; odds ratios (OR), 3.56; 95% CI, 1.04-12.21, P = 0.031), psoriasis (2.5 vs. 1.2%; OR, 2.12; 95% CI, 0.99-4.66; P = 0.050), and Hashimoto's thyroiditis (16.6 vs. 12.6%; OR, 1.38; 95% CI, 1.00-1.91; P = 0.049) was significantly higher in patients on DPP4i treatment than in controls. The prevalence of the remaining autoimmune diseases did not differ significantly between DPP4i-treated patients and their matched control subjects. In conclusion, this population-based study demonstrates an association of DPP4i intake with three autoimmune and inflammatory diseases noted to be part of a distinct autoimmune cluster that includes multiple sclerosis, psoriasis, thyroiditis, bullous pemphigoid, and inflammatory bowel disease. Experimental studies are required to define the role of DPP4i in this autoimmune cluster.

NF-κB/mTOR/MYC Axis Drives PRMT5 Protein Induction After T Cell Activation via Transcriptional and Non-transcriptional Mechanisms

Multiple sclerosis is an autoimmune disease of the central nervous system (CNS) mediated by CD4⁺ T cells and modeled via experimental autoimmune encephalomyelitis (EAE). Inhibition of PRMT5, the major Type II arginine methyltransferase, suppresses pathogenic T cell responses and EAE. PRMT5 is transiently induced in proliferating memory inflammatory Th1 cells and during EAE. However, the mechanisms driving PRMT5 protein induction and repression as T cells expand and return to resting is currently unknown. Here, we used naive mouse and memory mouse and human Th1/Th2 cells as models to identify mechanisms controlling PRMT5 protein expression in initial and recall T cell activation. Initial activation of naive mouse T cells resulted in NF-κB-dependent transient Prmt5 transcription and NF-κB, mTOR and MYC-dependent PRMT5 protein induction. In murine memory Th cells, transcription and miRNA loss supported PRMT5 induction to a lesser extent than in naive T cells. In contrast, NF-κB/MYC/mTOR-dependent non-transcriptional PRMT5 induction played a major role. These results highlight the importance of the NF-κB/mTOR/MYC axis in PRMT5-driven pathogenic T cell expansion and may guide targeted therapeutic strategies for MS.

The Short and Long-Term Effects of Pregnancy on Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

The role of pregnancy in multiple sclerosis (MS) is of importance because many patients with MS are young women in the childbearing age who require information to inform their reproductive decisions. Pregnancy is now well-known to be associated with fewer relapses of MS and reduced activity of autoimmune encephalomyelitis (EAE). However, in women with multiple sclerosis, this benefit is not always sufficient to protect against a rebound of disease activity if disease-modulating therapy is ceased for pregnancy. There is concern that use of assisted reproductive therapies can be associated with relapses of MS, but more data are required. It is thought that the beneficial effects of pregnancy are due to the pregnancy-associated changes in the maternal immune system. There is some evidence of this in human studies and studies of EAE. There is also evidence that having been pregnant leads to better long-term outcome of MS. The mechanism for this is not fully understood but it could result from epigenetic changes resulting from pregnancy or parenthood. Further studies of the mechanisms of the beneficial effects of pregnancy could provide information that might be used to produce new therapies.

[The treatment by expanded ex vivo autologous regulatory T-cells CD4+CD25+FoxP3+CD127low restores the balance of immune system in patients with remitting-relapsing multiple sclerosis]

AIM

To assess clinical efficacy and safety of the autologous (own) regulatory T-cells (Tregs)CD4+CD25+Foxp3+CD127low isolated from the blood of patients with remitting-relapsing multiple sclerosis. Patients with autoimmune diseases have the decreased number of peripheral Tregs (pTreg) and impaired suppressive ability. In order to restore levels of pTreg, it is possible to isolate precursor cells, enter expanded ex vivo autologous Treg cells and introduce an expanded amount of autologous cells as Treg vaccine.

MATERIAL AND METHODS

A method of ex vivo Tregs expansion by 30-40 times within 5-7 days has been developed. Expanded ex vivo Tregs are more than 90% CD4+CD25+Foxp3+CD127low and have high suppressor activity. Fourteen patients with remitting-relapsing multiple sclerosis were included in pilot studies.Ex vivoTregs were introduced subcutaneously in dosefrom 2.8 to 4.5 108 cell per injection. The duration of follow-up was 1 year.

RESULTS AND CONCLUSION

The numbers of pTregs in the blood of these patients elevated by 1.5-2 times. No adverse-effects, a decrease of relapses and stabilization of disability index were observed. It has been suggested that ex vivo expanded Tregs can compensate the impaired function of pTregs and can be used for adoptive immunotherapyof multiple sclerosis.

Potential disease biomarkers: dipeptidyl peptidase 4 and fibroblast activation protein

The importance of the dipeptidyl peptidase 4 (DPP4) gene family in regulating critical biochemical pathways continues to emerge. The two most well-studied members of the family, DPP4 and fibroblast activation protein (FAP), have been investigated both as therapeutic targets for disease and as diagnostic biomarkers. The interest in DPP4 and FAP as potential disease biomarkers has been driven primarily by observations of altered expression profiles in inflammatory diseases and cancer. Furthermore, the stability and persistence of soluble DPP4 and FAP in the serum make them attractive candidate serology markers. This review summarises investigations into DPP4 and FAP as biomarkers of autoimmune disease, gut inflammation, psychosomatic disorders and malignancy and discusses their potential likelihood as clinically useful tools.

Dipeptidyl peptidase-4 inhibitor use is not associated with elevated risk of severe joint pain in patients with type 2 diabetes: a population-based cohort study

This is the first large longitudinal cohort study to investigate the putative association of severe joint pain (SJP) with dipeptidyl peptidase-4 inhibitor (DPP4i) use in patients with type 2 diabetes. The propensity score-matched population-based cohort study was performed between 2009 and 2013 in a group of type 2 diabetes patients with stable metformin use. In total, 4743 patients with type 2 diabetes used a DPP4i as the second-line antidiabetic drug (ie, DPP4i users), and the same number of matched non-DPP4i users was selected. The 2 study groups were followed up until SJP diagnosis (International Classification of Diseases, Ninth Reversion, Clinical Modification code 719.4), health insurance policy termination, or the end of 2013. The incidence rate of SJP was estimated under the Poisson assumption. Multiple Cox proportional hazard model was used to estimate the covariate-adjusted hazard ratio and 95% CI of SJP in association with DPP4i use. Over a maximum follow-up of 5 years, 679 DPP4i users and 767 non-DPP4i users were newly diagnosed with SJP, representing incidence rates of 47.20 and 50.66 per 1000 person-years, respectively. Cox proportional hazard model indicated that DPP4i use slightly but nonsignificantly reduced the risk of SJP (adjusted hazard ratio: 0.92 [95% CI: 0.83-1.02]). Such null results were also observed among all age and sex stratifications and in a sensitivity analysis using all nonspecific arthropathies as the study endpoint. This study provides no support for the putative risk of SJP related to DPP4i use in type 2 diabetes patients during a maximum follow-up of 5 years.

Regional astrocyte IFN signaling restricts pathogenesis during neurotropic viral infection

Type I IFNs promote cellular responses to viruses, and IFN receptor (IFNAR) signaling regulates the responses of endothelial cells of the blood-brain barrier (BBB) during neurotropic viral infection. However, the role of astrocytes in innate immune responses of the BBB during viral infection of the CNS remains to be fully elucidated. Here, we have demonstrated that type I IFNAR signaling in astrocytes regulates BBB permeability and protects the cerebellum from infection and immunopathology. Mice with astrocyte-specific loss of IFNAR signaling showed decreased survival after West Nile virus infection. Accelerated mortality was not due to expanded viral tropism or increased replication. Rather, viral entry increased specifically in the hindbrain of IFNAR-deficient mice, suggesting that IFNAR signaling critically regulates BBB permeability in this brain region. Pattern recognition receptors and IFN-stimulated genes had higher basal and IFN-induced expression in human and mouse cerebellar astrocytes than did cerebral cortical astrocytes, suggesting that IFNAR signaling has brain region-specific roles in CNS immune responses. Taken together, our data identify cerebellar astrocytes as key responders to viral infection and highlight the existence of distinct innate immune programs in astrocytes from evolutionarily disparate regions of the CNS.

PRMT5-Selective Inhibitors Suppress Inflammatory T Cell Responses and Experimental Autoimmune Encephalomyelitis

In the autoimmune disease multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), expansion of pathogenic, myelin-specific Th1 cell populations drives active disease; selectively targeting this process may be the basis for a new therapeutic approach. Previous studies have hinted at a role for protein arginine methylation in immune responses, including T cell-mediated autoimmunity and EAE. However, a conclusive role for the protein arginine methyltransferase (PRMT) enzymes that catalyze these reactions has been lacking. PRMT5 is the main PRMT responsible for symmetric dimethylation of arginine residues of histones and other proteins. PRMT5 drives embryonic development and cancer, but its role in T cells, if any, has not been investigated. In this article, we show that PRMT5 is an important modulator of CD4⁺ T cell expansion. PRMT5 was transiently upregulated during maximal proliferation of mouse and human memory Th cells. PRMT5 expression was regulated upstream by the NF-κB pathway, and it promoted IL-2 production and proliferation. Blocking PRMT5 with novel, highly selective small molecule PRMT5 inhibitors severely blunted memory Th expansion, with preferential suppression of Th1 cells over Th2 cells. In vivo, PRMT5 blockade efficiently suppressed recall T cell responses and reduced inflammation in delayed-type hypersensitivity and clinical disease in EAE mouse models. These data implicate PRMT5 in the regulation of adaptive memory Th cell responses and suggest that PRMT5 inhibitors may be a novel therapeutic approach for T cell-mediated inflammatory disease.

Ex vivo expanded regulatory T cells CD4+CD25+FoxP3+CD127Low develop strong immunosuppressive activity in patients with remitting-relapsing multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease characterized by defect in regulatory function of CD4⁺CD25⁺ T cells. We demonstrated difference in proportion of regulatory T cells CD4⁺CD25⁺FoxP3⁺CD127^low (Tregs) within the same patients' relapse and remission. Proportion of peripheral Tregs (pTregs) dropped almost two times in the relapse compare to remission. Levels of pTregs in patients' remission were lower than in healthy donors. Suppressive ability of pTregs was decreased in MS patients compared to healthy donors. Injections of expanded ex vivo autologous Tregs (eTregs) could be helpful in bringing up the level of Tregs in patients' blood. We developed a simple method for ex vivo expansion of autologous Tregs within a short period of time. The final pool of cells consisted of 90-95% eTregs. When we started the culture with 10-20 × 10⁶ CD4⁺ T cells, we yield 300-400 × 10⁶ eTregs in a week. Expression of FoxP3 and Helios was calculated by two methods. Expanded ex vivo patients' and donors' Tregs were characterized by increased from three to five times expression of FoxP3, as well as almost doubled Helios expression. Peripheral Tregs in MS patients have decreased demethylation of FoxP3 gene promoter in comparison with donors. On the contrary, eTregs showed stable up-regulated demethylation without difference between MS patients and donors. MS patients' and donors' eTregs have much more suppressive ability than pTregs. Our data showed that eTregs can be applied as immunotherapy for MS patients and other autoimmune diseases if further investigated.

Serum immunologic markers in multiple sclerosis patients on continuous combined therapy with beta-interferon 1a, prednisone and azathioprine

Break-through symptoms (BTS) in multiple sclerosis (MS) patients on beta-interferon (beta-IFN) monotherapy are most frequently treated with a brief administration of steroids. Here, we report the results of monitoring serum immunologic markers recorded at three-month intervals for 1.5 years in responders to beta-INF 1a (Avonex) monotherapy ( n = 21) and MS patients placed on Avonex with prednisone ( n = 83) and Avonex, prednisone and azathioprine (AZA) ( n = 21) because of BTS. Compared to 23 healthy controls, patients on Avonex monotherapy and Avonex with prednisone, in individuals on Avonex, prednisone and AZA, a significant decrease in serum concentration of soluble intercellular adhesion molecule-1 (sICAM-1) ( P = 0.001) was established. Combined therapy with Avonex, prednisone and AZA was associated with a significant increase in the serum level of interleukin (IL)10 ( P < 0.001). Compared to Avonex monotherapy, combined therapy suppressed the serum level of IL12p40, antagonized elevation in the serum concentration of soluble IL2 receptor (sIL2R) and inhibited an increase in the serum soluble CD95 (sCD95) molecule. In patients studied, no significant differences in the serum level of IL18 and tumor necrosis factor-α (TNF-α) were established. These findings are important in understanding some of the immunoregulatory mechanisms induced by combined therapy in MS.

A highly immunogenic trivalent T cell receptor peptide vaccine for multiple sclerosis

Background: T cell receptor (TCR) peptide vaccination is a novel approach to treating multiple sclerosis (MS). The low immunogenicity of previous vaccines has hindered the development of TCR peptide vaccination for MS. Objective: To compare the immunogenicity of intramuscular injections of TCR BV5S2, BV6S5 and BV13S1 CDR2 peptides in incomplete Freund’s adjuvant (IFA) with intradermal injections of the same peptides without IFA. Methods: MS subjects were randomized to receive TCR peptides/IFA, TCR peptides/saline or IFA alone. Subjects were on study for 24 weeks. Results: The TCR peptides/IFA vaccine induced vigorous T cell responses in 100% of subjects completing the 24-week study (9/9) compared with only 20% (2/10) of those receiving the TCR peptides/saline vaccine (P =0.001). IFA alone induced a weak response in only one of five subjects. Aside from injection site reactions, there were no significant adverse events attributable to the treatment. Conclusions: The trivalent TCR peptide in IFA vaccine represents a significant improvement in immunogenicity over previous TCR peptide vaccines and warrants investigation of its ability to treat MS.

Serum lipid antibodies are associated with cerebral tissue damage in multiple sclerosis

Objective:

To determine whether peripheral immune responses as measured by serum antigen arrays are linked to cerebral MRI measures of disease severity in multiple sclerosis (MS).

Methods:

In this cross-sectional study, serum samples were obtained from patients with relapsing-remitting MS (n = 21) and assayed using antigen arrays that contained 420 antigens including CNS-related autoantigens, lipids, and heat shock proteins. Normalized compartment-specific global brain volumes were obtained from 3-tesla MRI as surrogates of atrophy, including gray matter fraction (GMF), white matter fraction (WMF), and total brain parenchymal fraction (BPF). Total brain T2 hyperintense lesion volume (T2LV) was quantified from fluid-attenuated inversion recovery images.

Results:

We found serum antibody patterns uniquely correlated with BPF, GMF, WMF, and T2LV. Furthermore, we identified immune signatures linked to MRI markers of neurodegeneration (BPF, GMF, WMF) that differentiated those linked to T2LV. Each MRI measure was correlated with a specific set of antibodies. Strikingly, immunoglobulin G (IgG) antibodies to lipids were linked to brain MRI measures. Based on the association between IgG antibody reactivity and each unique MRI measure, we developed a lipid index. This comprised the reactivity directed against all of the lipids associated with each specific MRI measure. We validated these findings in an additional independent set of patients with MS (n = 14) and detected a similar trend for the correlations between BPF, GMF, and T2LV vs their respective lipid indexes.

Conclusions:

We propose serum antibody repertoires that are associated with MRI measures of cerebral MS involvement. Such antibodies may serve as biomarkers for monitoring disease pathology and progression.

Dipeptidyl peptidase-4 inhibitors in type 2 diabetes may reduce the risk of autoimmune diseases: a population-based cohort study

OBJECTIVE

Dipeptidyl peptidase-4 (DPP4), also known as CD26, is a transmembrane glycoprotein that has a costimulatory function in the immune response. DPP4 inhibitors (DPP4i) are oral glucose-lowering drugs for type 2 diabetes mellitus (T2DM). This study evaluated the risk of incident rheumatoid arthritis (RA) and other autoimmune diseases (AD) such as systemic lupus erythematosus, psoriasis, multiple sclerosis and inflammatory bowel disease, associated with DPP4i in patients with T2DM.

METHODS

Using US insurance claims data (2005-2012), we conducted a population-based cohort study that included initiators of combination therapy with DPP4i (DPP4i plus metformin) and non-DPP4i (non-DPP4i plus metformin). RA and other AD were identified with ≥2 diagnoses and ≥1 dispensing for AD-specific immunomodulating drugs or steroids. Composite AD includes RA or other AD. Propensity score (PS)-stratified Cox proportional hazards models compared the risk of AD in DPP4i initiators versus non-DPP4i, controlling for potential confounders.

RESULTS

After asymmetric trimming on the PS, 73 928 patients with T2DM starting DPP4i combination therapy and 163 062 starting non-DPP4i combination therapy were selected. Risks of incident RA and composite AD were lower in the DPP4i group versus non-DPP4i with the PS-stratified HR of 0.66 (95% CI 0.44 to 0.99) for RA, 0.73 (0.51 to 1.03) for other AD and 0.68 (95% CI 0.52 to 0.89) for composite AD.

CONCLUSIONS

In this large cohort of diabetic patients, those initiating DPP4i combination therapy appear to have a decreased risk of incident AD including RA compared with those initiating non-DPP4i combination therapy. These results may suggest possible pharmacological pathways for prevention or treatment of AD.

Relapsing and progressive forms of multiple sclerosis: insights from pathology

PURPOSE OF REVIEW

The predominant clinical disease course of multiple sclerosis starts with reversible episodes of neurological disability, which transforms into progressive neurological decline. This review provides insight into the pathological differences during relapsing and progressive phases of multiple sclerosis.

RECENT FINDINGS

The clinical course of multiple sclerosis is variable, and the disease can be classified into relapsing and progressive phases. Pathological studies have been successful in distinguishing between these two forms of the disease and correlate with the clinical findings in terms of cellular responses, the inflammatory environment, and the location of lesions.

SUMMARY

Available therapies for multiple sclerosis patients, while effective during the relapsing phase, have little benefit for progressive multiple sclerosis patients. Development of therapies to benefit progressive multiple sclerosis patients will require a better understanding of the pathogenesis of progressive multiple sclerosis. This review discusses and compares the pathological findings in relapsing and progressive multiple sclerosis patients.

Low DPP4 expression and activity in multiple sclerosis

Multiple sclerosis (MS) is a prototypic Th1/Th17 chronic autoimmune disease of the central nervous system. Dipeptidyl peptidase 4 (DPP4 or CD26) is a multifunctional molecule involved in autoimmune diseases' pathophysiology. We sought to integrate disparate pieces of data and analyze the plasma levels of sDPP4, DPP activity and DPP4 surface expression on T-cells in 129 MS patients with different clinical forms and 53 healthy controls, across two independent cohorts. Herein, we provide new evidence that sDPP4 concentration and DPP activity are significantly lower in MS patients than controls (p < 0.0001 and p < 0.01, respectively). In contrast, the frequency of circulating CD8(+)DPP4(hi) T-cells (p = 0.02) was increased in MS patients. This is the first study that simultaneously analyzes DPP4 expression and function in a large cohort of MS patients. Our data indicate a putative role for DPP4 in MS pathophysiology and suggest that a deeper understanding of surface versus shed DPP4 biology is warranted.

Effect of natalizumab on circulating CD4+ T-cells in multiple sclerosis

In multiple sclerosis (MS), treatment with the monoclonal antibody natalizumab effectively reduces the formation of acute lesions in the central nervous system (CNS). Natalizumab binds the integrin very late antigen (VLA)-4, expressed on the surface of immune cells, and inhibits VLA-4 dependent transmigration of circulating immune-cells across the vascular endothelium into the CNS. Recent studies suggested that natalizumab treated MS patients have an increased T-cell pool in the blood compartment which may be selectively enriched in activated T-cells. Proposed causes are sequestration of activated T-cells due to reduced extravasation of activated and pro-inflammatory T-cells or due to induction of VLA-4 mediated co-stimulatory signals by natalizumab. In this study we examined how natalizumab treatment altered the distribution of effector and memory T-cell subsets in the blood compartment and if T-cells in general or myelin-reactive T-cells in particular showed signs of increased immune activation. Furthermore we examined the effects of natalizumab on CD4(+) T-cell responses to myelin in vitro. Natalizumab-treated MS patients had significantly increased numbers of effector-memory T-cells in the blood. In T-cells from natalizumab-treated MS patients, the expression of TNF-α mRNA was increased whereas the expression of fourteen other effector cytokines or transcription factors was unchanged. Natalizumab-treated MS patients had significantly decreased expression of the co-stimulatory molecule CD134 on CD4(+)CD26(HIGH) T-cells, in blood, and natalizumab decreased the expression of CD134 on MBP-reactive CD26(HIGH)CD4(+) T-cells in vitro. Otherwise CD4(+) T-cells from natalizumab-treated and untreated MS patients showed similar responses to MBP. In conclusion natalizumab treatment selectively increased the effector memory T-cell pool but not the activation state of T-cells in the blood compartment. Myelin-reactive T-cells were not selectively increased in natalizumab treated MS.

Endogenous and recombinant type I interferons and disease activity in multiple sclerosis

Although treatment of multiple sclerosis (MS) with the type I interferon (IFN) IFN-β lowers disease activity, the role of endogenous type I IFN in MS remains controversial. We studied CD4+ T cells and CD4+ T cell subsets, monocytes and dendritic cells by flow cytometry and analysed the relationship with endogenous type I IFN-like activity, the effect of IFN-β therapy, and clinical and magnetic resonance imaging (MRI) disease activity in MS patients. Endogenous type I IFN activity was associated with decreased expression of the integrin subunit CD49d (VLA-4) on CD4+CD26(high) T cells (Th1 helper cells), and this effect was associated with less MRI disease activity. IFN-β therapy reduced CD49d expression on CD4+CD26(high) T cells, and the percentage of CD4+CD26(high) T cells that were CD49d(high) correlated with clinical and MRI disease activity in patients treated with IFN-β. Treatment with IFN-β also increased the percentage of CD4+ T cells expressing CD71 and HLA-DR (activated T cells), and this was associated with an increased risk of clinical disease activity. In contrast, induction of CD71 and HLA-DR was not observed in untreated MS patients with evidence of endogenous type IFN I activity. In conclusion, the effects of IFN-β treatment and endogenous type I IFN activity on VLA-4 expression are similar and associated with control of disease activity. However, immune-activating effects of treatment with IFN-β may counteract the beneficial effects of treatment and cause an insufficient response to therapy.

Self-tolerance in multiple sclerosis

During the last decade, several defects in self-tolerance have been identified in multiple sclerosis. Dysfunction in central tolerance leads to the thymic output of antigen-specific T cells with T cell receptor alterations favouring autoimmune reactions. In addition, premature thymic involution results in a reduced export of naïve regulatory T cells, the fully suppressive clone. Alterations in peripheral tolerance concern costimulatory molecules as well as transcriptional and epigenetic mechanisms. Recent data underline the key role of regulatory T cells that suppress Th1 and Th17 effector cell responses and whose immunosuppressive activity is impaired in patients with multiple sclerosis. Those recent observations suggest that a defect in self-tolerance homeostasis might be the primary mover of multiple sclerosis leading to subsequent immune attacks, inflammation and neurodegeneration. The concept of multiple sclerosis as a consequence of the failure of central and peripheral tolerance mechanisms to maintain a self-tolerance state, particularly of regulatory T cells, may have therapeutic implications. Restoring normal thymic output and suppressive functions of regulatory T cells appears an appealing approach. Regulatory T cells suppress the general local immune response via bystander effects rather than through individual antigen-specific responses. Interestingly, the beneficial effects of currently approved immunomodulators (interferons β and glatiramer acetate) are associated with a restored regulatory T cell homeostasis. However, the feedback regulation between Th1 and Th17 effector cells and regulatory T cells is not so simple and tolerogenic mechanisms also involve other regulatory cells such as B cells, dendritic cells and CD56(bright) natural killer cells.

NPY suppressed development of experimental autoimmune encephalomyelitis in Dark Agouti rats by disrupting costimulatory molecule interactions

Neuropeptide Y (NPY) suppressed clinical experimental autoimmune encephalomyelitis (EAE) and reduced numbers of CD28+, CD11b+ and CD80+ cells among spinal cord infiltrating cells at the peak of disease in Dark Agouti rat strain. Suppression of EAE was accompanied by the reduced expression of costimulatory CD80 and CD86 molecules on ED1+ macrophages and OX62+ dendritic cells in draining lymph nodes during the inductive phase of EAE. An inhibitor of dipeptidyl peptidase 4, an enzyme which terminates the action of NPY on Y1 receptor subtype, did not sustain the suppressive effect of NPY on the EAE development, suggesting involvement of Y2 and Y5 receptors.

Gene expression profiling in multiple sclerosis brain

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system and the leading cause of non-traumatic neurological disability in young adults in the United States and Europe. The clinical disease course is variable and starts with reversible episodes of neurological disability in the third or fourth decade of life. Microarray-based comparative gene profiling provides a snapshot of genes underlying a particular condition. Several large scale microarray studies have been conducted using brain tissue from MS patients. In this review, we summarize existing data from different gene expression profiling studies and how they relate to understand the pathogenesis of MS.

Modulation of the central memory and Tr1-like regulatory T cells in multiple sclerosis patients responsive to interferon-beta therapy

Background: Interferon-beta is used to reduce disease activity in multiple sclerosis, but its action is incompletely understood, individual treatment response varies among patients, and biological markers predicting clinical benefits have yet to be identified. Since it is known that multiple sclerosis patients have a deficit of the regulatory T-cell subsets, we investigated whether interferon-beta therapy induced modifications of the two main categories of regulatory T cells (Tregs), natural and IL-10-secreting inducible Tr1 subset, in patients who are biologically responsive to the therapy.

Methods: T-cell phenotype was determined by flow cytometry, while real-time PCR was used to evaluate interferon-beta bioactivity through MxA determination, and to measure the RNA for IL-10 and CD46 molecule in peripheral blood mononuclear cells stimulated with anti-CD46 and anti-CD3 monoclonal antibodies, which are known to expand a Tr1-like population.

Results: Interferon-beta induced a redistribution of natural Treg subsets with a shift of naive Tregs towards the ‘central memory-like’ Treg population that expresses the CCR7 molecule required for the in vivo suppressive activity. Furthermore, in a subgroup of treated patients, the CD46/CD3 co-stimulation, probably through the Tr1-like subset modulation, increased the production of RNA for IL-10 and CD46. The same group showed a lower median EDSS score after two years of therapy.

Conclusions: The selective increase of ‘central memory-like’ subset and the involvement of the Tr1-like population may be two of the mechanisms by which interferon-beta achieves its beneficial effects. The quantification of RNA for IL-10 and CD46 could be used to identify patients with a different response to interferon-beta therapy.

Deferiprone modulates in vitro responses by peripheral blood T cells from control and relapsing-remitting multiple sclerosis subjects

T cells are important mediators of autoimmune inflammation in relapsing-remitting multiple sclerosis (RRMS). Previous studies found that deferiprone, an iron chelator, suppressed disease activity in a mouse model of multiple sclerosis, and inhibition of T cell proliferation was implicated as a putative mechanism. The objective of the present study was to examine the effects of deferiprone on suppressing in vitro responses of T cells from control and RRMS subjects. Peripheral blood T cells were co-stimulated with anti-CD3+anti-CD28 and cultured with or without interleukin 2 (IL-2). Proliferating CD4+ T cells from control and RRMS subjects, cultured with or without IL-2, decreased in response to 75 μM deferiprone, although the extent of decreased proliferation of CD4+ T cells from RRMS subjects was less than for control subjects. Proliferating CD8+ T cells from control subjects, cultured with or without IL-2, also decreased in response to 75 μM deferiprone, and this decrease was seen in proliferating CD8+ T cells from RRMS cultured with IL-2. CD4+CD25+ and CD8+CD25+ cells from control subjects, cultured with or without IL-2, declined in 75 μM deferiprone, but the decrease was smaller than for the CD4+ and CD8+ proliferative responses. CD4+CD25+ and CD8+CD25+ cells from RRMS subjects showed more variability than for control subjects, but CD4+CD25+ cultured with IL-2 and CD8+CD25+ cells cultured without IL-2 significantly declined in 75 μM deferiprone. CD4+FoxP3+ and CD4+CD25+FoxP3+ cells tended to remain constant or increase. In summary, deferiprone induced declines in proliferative responses at a dosage that is within peak serum pharmacological concentrations.

The type of responder T-cell has a significant impact in a human in vitro suppression assay

Background

In type 1 diabetes (T1D), a prototypic autoimmune disease, effector T cells destroy beta cells. Normally, CD4⁺CD25^+high, or natural regulatory T cells (Tregs), counter this assault. In autoimmunity, the failure to suppress CD4⁺CD25^low T cells is important for disease development. However, both Treg dysfunction and hyperactive responder T-cell proliferation contribute to disease.

Methods/Principal Findings

We investigated human CD4⁺CD25^low T cells and compared them to CD4⁺CD25^- T cells in otherwise equivalent in vitro proliferative conditions. We then asked whether these differences in suppression are exacerbated in T1D. In both single and co-culture with Tregs, the CD4⁺CD25^low T cells divided more rapidly than CD4⁺CD25^- T cells, which manifests as increased proliferation/reduced suppression. Time-course experiments showed that this difference could be explained by higher IL-2 production from CD4+CD25^low compared to CD4+CD25- T cells. There was also a significant increase in CD4+CD25^low T-cell proliferation compared to CD4+CD25- T cells during suppression assays from RO T1D and at-risk subjects (n = 28, p = 0.015 and p = 0.024 respectively).

Conclusions/Significance

The in vitro dual suppression assays proposed here could highlight the impaired sensitivity of certain responder T cells to the suppressive effect of Tregs in human autoimmune diseases.

Mechanisms of neuronal dysfunction and degeneration in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. Due to its high prevalence, MS is the leading cause of non-traumatic neurological disability in young adults in the United States and Europe. The clinical disease course is variable and starts with reversible episodes of neurological disability in the third or fourth decade of life. This transforms into a disease of continuous and irreversible neurological decline by the sixth or seventh decade. Available therapies for MS patients have little benefit for patients who enter this irreversible phase of the disease. It is well established that irreversible loss of axons and neurons are the major cause of the irreversible and progressive neurological decline that most MS patients endure. This review discusses the etiology, mechanisms and progress made in determining the cause of axonal and neuronal loss in MS.

Stability of immunophenotypic markers in fixed peripheral blood for extended analysis using flow cytometry

The analysis of whole blood samples by flow cytometry for pharmacodynamic and biomarker assessments in clinical studies has been limited by the necessity to test these samples within a short time frame after blood collection. In most clinical studies, blood specimens are shipped to a centralized testing facility; it is critical to demonstrate specimen stability over a period of time which will encompass the time elapsed between specimen collection and testing. A possible solution to overcome this limitation is the use of a fixative to preserve the cell surface antigen stability in whole blood. We examined the stability of markers for T lymphocytes (CD3, CD4, CD8, CD45RA, and CD45RO), B lymphocytes (CD19), NK cells (CD16+CD56), activation (CD25 and HLA-DR), chemokine receptors (CCR5 and CXCR3) and skin homing (CLA) in fixed blood over 7 days and used this information to select the markers for global clinical studies. These assays with selected markers were further validated using fit-for-purpose approach (Lee et al., 2006) and to set the sample acceptability criteria for use in clinical sample testing. Most of the markers examined were stable when collected in Cyto-Chex® BCT for one week with the exception of the activation markers on T cells.

Contribution of CD8 T lymphocytes to the immuno-pathogenesis of multiple sclerosis and its animal models

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) characterized by multi-focal demyelination, axonal loss, and immune cell infiltration. Numerous immune mediators are detected within MS lesions, including CD4(+) and CD8(+) T lymphocytes suggesting that they participate in the related pathogenesis. Although CD4(+) T lymphocytes are traditionally considered the main actors in MS immunopathology, multiple lines of evidence suggest that CD8(+) T lymphocytes are also implicated in the pathogenesis. In this review, we outline the recent literature pertaining to the potential roles of CD8(+) T lymphocytes both in MS and its animal models. The CD8(+) T lymphocytes detected in MS lesions demonstrate characteristics of activated and clonally expanded cells supporting the notion that these cells actively contribute to the observed injury. Moreover, several experimental in vivo models mediated by CD8(+) T lymphocytes recapitulate important features of the human disease. Whether the CD8(+) T cells can induce or aggravate tissue destruction in the CNS needs to be fully explored. Strengthening our understanding of the pathogenic potential of CD8(+) T cells in MS should provide promising new avenues for the treatment of this disabling inflammatory disease.

Update on inflammation, neurodegeneration, and immunoregulation in multiple sclerosis: therapeutic implications

Multiple sclerosis (MS) is an inflammatory, demyelinating, and neurodegenerative disease of the central nervous system of uncertain etiology. There is consensus that a dysregulated immune system plays a critical role in the pathogenesis of MS; therefore, we aim to summarize current hypotheses concerning the complex cellular and molecular interactions involved in the immunopathology of MS. Although CD4+ T lymphocytes have long been implicated in the immunopathology of MS, the role of other T-cell subtypes has been recognized. CD4+ and CD8+ cells have been isolated from different locations within MS lesions and gamma/delta T cells have been isolated from early MS lesions. The prevalent dogma has been that CD4+ TH1 cells release cytokines and mediators of inflammation that may cause tissue damage, although CD4+ TH2 cells may be involved in modulation of these effects. Recent evidence, however, suggests that additional T-cell subsets play a prominent role in MS immunopathology: TH17 cells, CD8+ effector T cells, and CD4+CD25+ regulatory T cells. In addition, laboratory and clinical data are accumulating on the prominent role of B lymphocytes and antigen-presenting cells in MS pathogenesis. On the basis of these observations, new therapeutic approaches for MS will need to focus on resetting multiple components of the immune system.

Clinical response to interferon-beta-1a may be linked to low baseline circulating BDCA1 myeloid dendritic cells Differential role of circulating dendritic cells and CD4+ regulatory T-cells in relapsing-remitting multiple sclerosis: a 1-year longitudinal study

Many variables with association with better response to interferon-beta-1a (IFNbeta-1a) have been described, but none has yet been shown to be predictive of clinical response. In this real-life observational 1-year longitudinal study of 23 relapsing-remitting multiple sclerosis (RRMS) patients treated with subcutaneous IFNbeta-1a, we have shown a lower proportion of circulating myeloid dendritic cells (mDCs) than in healthy controls at baseline. Both univariate (Kaplan-Meier) and multivariate (Cox regression) analyses were conducted to determine which variables (age, sex, baseline EDSS, MS relapse rates 1 year and 2 years before initiating IFNbeta-1a, mDCs and plasmacytoid (pDCs) subsets, activated and regulatory CD4(+) T-cells (T(Reg))) were associated with clinical response to IFNbeta-1a. During 1 year of treatment, we observed a shift towards lower proportions of CD123(+) pDCs expression and higher numbers and function of the T(Reg). Univariate analysis disclosed that MS activity was significantly associated with baseline BDCA1(+) mDCs below < or = 0.4% (p<0.0025). Cox model analysis revealed that baseline BDCA1(+) mDCs was the most closely associated factor with MS activity on IFN treatment during the 1-year follow-up (p<0.01). A better understanding of the rules that govern the T(Reg)-DC relationship will enable scientists to better manage the immune response in MS patients.

The challenge of multiple sclerosis: how do we cure a chronic heterogeneous disease?

Multiple sclerosis is (MS) a T-cell autoimmune disease characterized by a relapsing-remitting followed by a progressive phase. Relapses are driven by the adaptive immune system and involve waves of T helper cell 1 (Th1), Th17, and CD8 cells that infiltrate the nervous system and provoke a attack. These cells are modulated by regulatory T and B cells. Infiltration of T cells into the nervous system initiates a complex immunological cascade consisting of epitope spreading, which triggers new attacks, and activation of the innate immune system (microglia, dendritic cells, astrocytes, B cells), which leads to chronic inflammation. The secondary progressive phase is due to neurodegeneration triggered by inflammation and is driven by the innate immune system. Why a shift to the progressive stage occurs and how to prevent it is a central question in MS. Effective treatment of MS must affect multiple disease pathways: suppression of proinflammatory T cells, induction of regulatory T cells, altering traffic of cells into the nervous system, protecting axons and myelin, and controlling innate immune responses. Without biomarkers, the clinical and pathological heterogeneity of MS makes treatment difficult. Treatment is further hampered by untoward adverse effects caused by immune suppression. Nonetheless, major progress has been made in the understanding and treatment of MS. There are three definitions of cure as it applies to MS: (1) halt progression of disease, (2) reverse neurological deficits, and (3) prevent MS. Although the pathways to each of these cures are linked, each requires a unique strategy.

Genetic association of HLA DQB1 with CD4+CD25+(high) T-cell apoptosis in type 1 diabetes

Type 1 diabetes (T1D) has a strong genetic component and the major locus lies in the HLA DQB1 region. We found earlier an increased apoptosis with decreased viability and function of the CD4+CD25+(high) T-cell subset (Treg) in human subjects with recent-onset T1D and in multiple autoantibody-positive, high at-risk individuals. Tregs normally inhibit or delay onset of T1D in animal models and increased Treg apoptosis could bring on or accelerate disease from effector T-cell-mediated destruction of insulin-producing beta cells. In this study, we test the hypothesis that HLA DQB1 genotypes are associated with increased CD4+CD25+(high) T-cell apoptosis. HLA DQ-based genetic risk status was significantly associated with CD4+CD25+(high) T-cell apoptosis, after adjustment for age, gender and phenotypic status (n=83, F=4.04 (d.f.=3), P=0.01). Unaffected, autoantibody-negative high risk HLA DQB1 control subjects showed increased CD4+CD25+(high) apoptosis levels compared with low risk HLA DQB1 control subjects (n=26, P=0.002), confirming that the association precedes disease. The association of specific HLA DQB1 genotypes with Treg apoptosis was also tested, showing significance for HLA DQB1*0302, DQB1*0201 and HLA DQB1*0602 alleles. Our study shows an association of HLA DQB1 genotypes with CD4+CD25+(high) T-cell apoptosis, which implicates CD4+CD25+(high) T-cell apoptosis as a new intermediate trait for T1D.

Expression of the inhibitor of apoptosis protein family in multiple sclerosis reveals a potential immunomodulatory role during autoimmune mediated demyelination

A failure of autoreactive T cells to undergo apoptosis may contribute to the pathogenesis of multiple sclerosis (MS). The role of the inhibitor of apoptosis (IAP) family of anti-apoptotic proteins such as X-linked IAP (XIAP), human inhibitor of apoptosis-1 (HIAP-1), human inhibitor of apoptosis-2 (HIAP-2), neuronal apoptosis inhibitory protein (NAIP) and Survivin in relapsing–remitting, secondary-progressive, primary-progressive or benign forms of MS is unclear. We report here that expression of the IAP family of genes in peripheral blood samples and brain tissues from MS cases support a role for differential regulation of these potent anti-apoptotic proteins in the pathology of MS. XIAP mRNA and protein levels were elevated in peripheral blood mononuclear cells from patients with active disease relative to normal subjects. In patients with active MS, HIAP-1 and HIAP-2 mRNA levels were elevated in resting T cells while NAIP mRNA was increased in whole blood. In post-mortem MS brain tissue, XIAP and HIAP-1 in myelin lesions were co-localized with microglia and T cells, respectively. Only in primary-progressive patients was Survivin expression elevated suggestive of a distinct pathological basis for this subtype of MS. Taken together, these results suggest that patterns of inhibitor of apoptosis expression in immune cells may have value in distinguishing between MS subtypes and offer insight into the mechanisms responsible for their distinct clinical courses.

Thymic output and peripheral T lymphocyte subsets in relapsing--remitting multiple sclerosis patients treated or not by IFN-beta

We explored the parameters of central and peripheral tolerance in patients with stable relapsing-remitting multiple sclerosis, treated or not with IFN-beta. TREC-positive T cells were lower in patients compared with controls, mainly in CD4+ subset, compatible with a thymus dysfunction or an expansion of peripheral lymphocytes. Compared to controls, the frequency of activated CD4+CD25+ T cells was higher in patients without modification of the CD4+CD25(high) T cell proportion. The IFN-beta-treatment did not modify the TREC-positive cell frequency nor the naive/memory T cell subset percentage but was associated with lower blood lymphocyte count and a lower frequency of CD4+CD45RC(high) subset.

Time-series modeling of multiple sclerosis disease activity: a promising window on disease progression and repair potential?

This article discusses and reviews advanced forms of serial morphometry in the context of a disease progression model in multiple sclerosis (MS). This model of disease activity distinguishes between overall disease activity and the proportion thereof that becomes permanent damage. This translates into a progression model that features a repair potential, which, when exhausted, marks the conversion or progression from relapsing to progressive disease. The level of repair capacity at a given time determines the rate of progression. Both clinical and MRI variables appear to be in support of such a model. We examine possible MRI markers for this repair capacity, particularly the short-term behavior of new MRI lesions, quantified by methods of time-series analysis--that is, capturing lesion dynamics in the form of MRI intensity change directly, rather than shape or volume change. Lower rates of individual lesion recovery may represent lower repair and greater proximity to a progressive stage. Individuals with low transient lesion turnover appear to undergo more rapid progression and atrophy. Because disease-modifying therapies aim to alter the pathophysiological chain of inflammation, demyelination, and axonal loss, a therapeutic effect may therefore be more readily apparent as a change in lesion dynamics and recovery rate and level, rather than a change in total lesion burden or enhancing lesion number.

TGF-beta1-mediated control of central nervous system inflammation and autoimmunity through the inhibitory receptor CD26

The T cell marker CD26/dipeptidyl peptidase (DP) IV is associated with an effector phenotype and markedly elevated in the human CNS disorder multiple sclerosis. However, little is known about the in vivo role of CD26/DP IV in health and disease, and the underlying mechanism of its function in CNS inflammation. To directly address the role of CD26/DP IV in vivo, we examined Th1 immune responses and susceptibility to experimental autoimmune encephalomyelitis in CD26(-/-) mice. We show that gene deletion of CD26 in mice leads to deregulation of Th1 immune responses. Although production of IFN-gamma and TNF-alpha by pathogenic T cells in response to myelin Ag was enhanced in CD26(-/-) mice, production of the immunosuppressive cytokine TGF-beta1 was diminished in vivo and in vitro. In contrast to the reduction in TGF-beta1 production, responsiveness to external TGF-beta1 was normal in T cells from CD26(-/-) mice, excluding alterations in TGF-beta1 sensitivity as a mechanism causing the loss of immune regulation. Natural ligands of CD26/DP IV induced TGF-beta1 production in T cells from wild-type mice. However, natural ligands of CD26/DP IV failed to elicit TGF-beta1 production in T cells from CD26(-/-) mice. The striking functional deregulation of Th1 immunity was also seen in vivo. Thus, clinical experimental autoimmune encephalomyelitis scores were significantly increased in CD26(-/-) mice immunized with peptide from myelin oligodendrocyte glycoprotein. These results identify CD26/DP IV as a nonredundant inhibitory receptor controlling T cell activation and Th1-mediated autoimmunity, and may have important therapeutic implications for the treatment of autoimmune CNS disease.

Expression of ectonucleotidase CD39 by Foxp3+ Treg cells: hydrolysis of extracellular ATP and immune suppression

In the immune system, extracellular ATP functions as a "natural adjuvant" that exhibits multiple proinflammatory effects. It is released by damaged cells as an indicator of trauma and cell death but can be inactivated by CD39 (nucleoside triphosphate diphosphohydrolase-1 [NTPDase 1]), an ectoenzyme that degrades ATP to AMP. Here, we show that CD39 is expressed primarily by immune-suppressive Foxp3(+) regulatory T (Treg) cells. In mice, the enzyme is present on virtually all CD4(+)CD25(+) cells. CD39 expression is driven by the Treg-specific transcription factor Foxp3 and its catalytic activity is strongly enhanced by T-cell receptor (TCR) ligation. Activated Treg cells are therefore able to abrogate ATP-related effects such as P2 receptor-mediated cell toxicity and ATP-driven maturation of dendritic cells. Also, human Treg cells express CD39. In contrast to mice, CD39 expression in man is restricted to a subset of Foxp3(+) regulatory effector/memory-like T (T(REM)) cells. Notably, patients with the remitting/relapsing form of multiple sclerosis (MS) have strikingly reduced numbers of CD39(+) Treg cells in the blood. Thus, in humans CD39 is a marker of a Treg subset likely involved in the control of the inflammatory autoimmune disease.

Dose-dependent recruitment of CD25+ and CD26+ T cells in a novel F344 rat model of asthma

The ovalbumin (OVA)-induced airway inflammation in rats is a commonly used model to explore the pathobiology of asthma. However, its susceptibility varies greatly between rat strains, and presently Brown Norway (BN) rats are preferentially used. Since recruitment of T cells to the lungs depends on the CD26 (dipeptidyl peptidase IV, DPPIV) expression, Fischer 344 strain (F344) rats are a highly relevant rat strain, in particular because CD26-deficient substrains are available. To establish a F344 rat model of asthma, we challenged F344 rats using different doses of aerosolized antigen (0%, 1%, 2.5%, 5%, and 7.5% OVA) and compared these effects with intratracheal instillation of OVA (1.5 mg/0.3 ml). Asthmoid responsiveness was determined by analysis of early airway responsiveness (EAR), antigen-specific IgE levels, as well as airway inflammation including the composition of T cell subpopulations in the bronchoalveolar lavage (BAL) and lung tissue with special respect to the T cell activation markers CD25 and CD26. Even low allergen doses caused allergen-specific EAR and increases of antigen-specific IgE levels. However, EAR and IgE levels did not increase dose dependently. Higher concentrations of OVA led to a dose-dependent increase of several immunological markers of allergic asthma including an influx of eosinophils, T cells, and dendritic cells. Interestingly, a dose-dependent increase of CD4(+)/CD25(+)/CD26(+) T cells was found in the lungs. Summarizing, we established a novel F344 rat model of aerosolized OVA-induced asthma. Thereby, we found a dose-dependent recruitment of cellular markers of allergic asthma including the activated CD4(+)/CD25(+)/CD26(+) T cell subpopulation, which has not been described in asthma yet.

Interferon beta-1a therapy enhances CD4+ regulatory T-cell function: an ex vivo and in vitro longitudinal study in relapsing-remitting multiple sclerosis

Interferon beta-1a (IFNâ-1a) has demonstrated efficacy in multiple sclerosis (MS), although its mechanism of action remains only partly understood. We evaluated the ex vivo and in vitro effects of IFNâ-1a (Rebif) on regulatory T-cell (T(Reg)) function in 22 relapsing-remitting MS patients and 16 healthy controls. T(Reg) function was significantly enhanced after 3 and 6 months of IFNbeta-1a therapy. Furthermore, there was a trend towards increasing proportions of total CD4(+)CD25(+) and CD4(+)CD25(+)GITR(+) T(Reg) after 6 months of IFNbeta-1a therapy when compared with baseline. In conclusion, IFNbeta-1a therapy enhances T(Reg) function, and this may be relevant in the inflammatory environment of MS lesions.

CD4(+) memory T cells with high CD26 surface expression are enriched for Th1 markers and correlate with clinical severity of multiple sclerosis

An aberrant immune activation is believed to be important in the pathogenesis of multiple sclerosis (MS). Expression of CD4(+) T lymphocyte surface molecules indicative of immune activation and effector functions has been correlated with disease severity and activity. CD4(+) CD45R0(+) CD26(high) memory T lymphocytes contained the high levels of markers of Th1, activation, and effector functions and cell counts of this subset correlated with MS disease severity. This subset had lower expression of PD-1, CCR4, and L-selectin in MS than in controls. These changes were only partially normalised by treatment with interferon-beta. We point to this subset as a putative target for immunological monitoring of MS disease activity and of treatment efficacy.

CD4+CD25+FoxP3+ T lymphocytes fail to suppress myelin basic protein-induced proliferation in patients with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disorder directed against self antigens of the central nervous system. CD4(+)CD25(+)FoxP3(+) regulatory T cell (T(reg)) mediated suppression is an essential mechanism of self-tolerance. We studied whether changes in the suppressive function of a mixture of CD25(high) and CD25(intemediate) expressing T(reg) cells in myelin basic protein (MBP)-induced proliferation occurred in untreated MS patients. Suppression of MBP-induced proliferation was observed in 13 out of 29 (45%) MS patients; this was significantly (p<0.05) less compared with 17 out of 19 (89%) healthy individuals. Relative T(reg) counts was significantly increased in MS patients (mean+/-S.D.; 20+/-8%) compared with healthy individuals (15+/-5%). These findings suggest that impaired T(reg) function may be involved in pathogenesis of MS.