Disease activity in multiple sclerosis correlates with T lymphocyte expression of the inhibitor of apoptosis proteins

Chasing shadows: Cytologically detected shadow cells in the cerebrospinal fluid of patients with multiple sclerosis

BACKGROUND

Pathophysiology of multiple sclerosis (MS) is dominated by both inflammation and neurodegeneration. A correlation between inflammation and regulated cell death has been suggested previously. Shadow cells in the cerebrospinal fluid (CSF) are considered apoptotic cells.

OBJECTIVE

To assess the occurrence of shadow cells in MS patients in comparison to other neurological diseases (OND).

METHODS

We conducted cytological examination of CSF in 114 MS patients and 125 patients with OND, who had diagnostic lumbar puncture at the Department of Neurology, Medical University of Innsbruck, with time to laboratory processing ≤0.5 h, showed a CSF white blood cell (WBC) count ≤50/µl and a red blood cell (RBC) count ≤500/µl. Shadow cells were counted by two blinded, independent, experienced investigators, using a standardized approach on microscopic slides.

RESULTS

The number of shadow cells did not statistically significantly differ between patients with MS (median: 12, IQR: 0-85) and OND (median 6, IQR: 0-94; p = 0.106). Multivariable regression analysis including age, sex, time to laboratory processing, CSF WBC and RBC count, CSF/serum glucose ratio, CSF/serum albumin quotient and disease group as independent variables, identified WBC count as significant predictor of shadow cells (β [ln WBC count]=0.73, p<10^-9), whereas the disease group had no impact (p = 0.466).

CONCLUSIONS

Occurrence of shadow cells in the CSF seems to depend on the extent of inflammatory cells rather than MS disease-specific mechanisms.

Contribution of Apaf-1 to the pathogenesis of cancer and neurodegenerative diseases

Deregulation of apoptosis is associated with various pathologies, such as neurodegenerative disorders at one end of the spectrum and cancer at the other end. Generally speaking, differentiated cells like cardiomyocytes, skeletal myocytes and neurons exhibit low levels of Apaf-1 (Apoptotic protease activating factor 1) protein suggesting that down-regulation of Apaf-1 is an important event contributing to the resistance of these cells to apoptosis. Nonetheless, upregulation of Apaf-1 has not emerged as a common phenomenon in pathologies associated with enhanced neuronal cell death, i.e., neurodegenerative diseases. In cancer, on the other hand, Apaf-1 downregulation is a common phenomenon, which occurs through various mechanisms including mRNA hyper-methylation, gene methylation, Apaf-1 localization in lipid rafts, inhibition by microRNAs, phosphorylation, and interaction with specific inhibitors. Due to the diversity of these mechanisms and involvement of other factors, defining the exact contribution of Apaf-1 to the development of cancer in general and neurodegenerative disorders, in particular, is complicated. The current review is an attempt to provide a comprehensive image of Apaf-1's contribution to the pathologies observed in cancer and neurodegenerative diseases with the emphasis on the therapeutic aspects of Apaf-1 as an important target in these pathologies.

Reversibility of the effects of natalizumab on peripheral immune cell dynamics in MS patients

OBJECTIVE

To characterize the reversibility of natalizumab-mediated changes in pharmacokinetics/pharmacodynamics in patients with multiple sclerosis (MS) following therapy interruption.

METHODS

Pharmacokinetic/pharmacodynamic data were collected in the Safety and Efficacy of Natalizumab in the Treatment of Multiple Sclerosis (AFFIRM) (every 12 weeks for 116 weeks) and Randomized Treatment Interruption of Natalizumab (RESTORE) (every 4 weeks for 28 weeks) studies. Serum natalizumab and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured using immunoassays. Lymphocyte subsets, α4-integrin expression/saturation, and vascular cell adhesion molecule-1 (VCAM-1) binding were assessed using flow cytometry.

RESULTS

Blood lymphocyte counts (cells/L) in natalizumab-treated patients increased from 2.1 × 10⁹ to 3.5 × 10⁹. Starting 8 weeks post last natalizumab dose, lymphocyte counts became significantly lower in patients interrupting treatment than in those continuing treatment (3.1 × 10⁹ vs 3.5 × 10⁹; p = 0.031), plateauing at prenatalizumab levels from week 16 onward. All measured cell subpopulation, α4-integrin expression/saturation, and sVCAM changes demonstrated similar reversibility. Lymphocyte counts remained within the normal range. Ex vivo VCAM-1 binding to lymphocytes increased until ≈16 weeks after the last natalizumab dose, then plateaued, suggesting reversibility of immune cell functionality. The temporal appearance of gadolinium-enhancing lesions was consistent with pharmacodynamic marker reversal.

CONCLUSIONS

Natalizumab's effects on peripheral immune cells and pharmacodynamic markers were reversible, with changes starting 8 weeks post last natalizumab dose; levels returned to those observed/expected in untreated patients ≈16 weeks post last dose. This reversibility differentiates natalizumab from MS treatments that require longer reconstitution times. Characterization of the time course of natalizumab's biological effects may help clinicians make treatment sequencing decisions.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that the pharmacodynamic markers of natalizumab are reversed ≈16 weeks after stopping natalizumab.

Recombinant human PDCD5 (rhPDCD5) protein is protective in a mouse model of multiple sclerosis

Background

In multiple sclerosis (MS) and its widely used animal model, experimental autoimmune encephalomyelitis (EAE), autoreactive T cells contribute importantly to central nervous system (CNS) tissue damage and disease progression. Promoting apoptosis of autoreactive T cells may help eliminate cells responsible for inflammation and may delay disease progression and decrease the frequency and severity of relapse. Programmed cell death 5 (PDCD5) is a protein known to accelerate apoptosis in response to various stimuli. However, the effects of recombinant human PDCD5 (rhPDCD5) on encephalitogenic T cell-mediated inflammation remain unknown.

Methods

We examined the effects of intraperitoneal injection of rhPDCD5 (10 mg/kg) on EAE both prophylactically (started on day 0 post-EAE induction) and therapeutically (started on the onset of EAE disease at day 8), with both of the treatment paradigms being given every other day until day 25. Repeated measures two-way analysis of variance was used for statistical analysis.

Results

We showed that the anti-inflammatory effects of rhPDCD5 were due to a decrease in Th1/Th17 cell frequency, accompanied by a reduction of proinflammatory cytokines, including IFN-γ and IL-17A, and were observed in both prophylactic and therapeutic regimens of rhPDCD5 treatment in EAE mice. Moreover, rhPDCD5-induced apoptosis of myelin-reactive CD4⁺ T cells, along with the upregulation of Bax and downregulation of Bcl-2, and with activated caspase 3.

Conclusions

Our data demonstrate that rhPDCD5 ameliorates the autoimmune CNS disease by inhibiting Th1/Th17 differentiation and inducing apoptosis of predominantly pathogenic T cells. This study provides a novel mechanism to explain the effects of rhPDCD5 on neural inflammation. The work represents a translational demonstration that rhPDCD5 has prophylactic and therapeutic properties in a model of multiple sclerosis.

Analysis of apoptosis-related genes in patients with clinically isolated syndrome and their association with conversion to multiple sclerosis

To analyse whether the expression of apoptotic transcripts is associated with the conversion from clinically isolated syndrome (CIS) to multiple sclerosis (MS). Eleven candidate transcripts belonging to the death receptor pathway, BCL-2, the inflammasome complex and NF-ΚB family were studied in the nonconverting and converting CIS patients during the four-year follow-up period. Conversion to MS was associated with marked variability in the expression of proapoptotic genes that were linked to TGF-B1 gene levels. The predominant expression of proapoptotic genes in patients with CIS suggests an increased potential to undergo apoptosis with the goal of terminating immune responses and regulating immune system homeostasis.

Targeting apoptosis in autoimmune hepatitis

Apoptosis is the predominant mechanism of liver cell death in autoimmune hepatitis, and interventions that can modulate this activity are emerging. The aim of this review was to describe the apoptotic mechanisms, possible aberrations, and opportunities for intervention in autoimmune hepatitis. Studies cited in PubMed from 1972 to 2014 for autoimmune hepatitis, apoptosis in liver disease, apoptosis mechanisms, and apoptosis treatment were examined. Apoptosis is overactive in autoimmune hepatitis, and the principal pathway of cell death is receptor mediated. Surface death receptors are activated by extrinsic factors including liver-infiltrating cytotoxic T cells and the cytokine milieu. The executioner caspases 3 and 7 cleave nuclear deoxyribonucleic acid, and the release of apoptotic bodies can stimulate inflammatory, immune, and fibrotic responses. Changes in mitochondrial membrane permeability can be initiated by caspase 8, and an intrinsic pathway of apoptosis can complement the extrinsic pathway. Defects in the apoptosis of activated effector cells can prolong their survival and sustain the immune response. Caspase inhibitors have been used in diverse experimental and human diseases to retard apoptosis. Oligonucleotides that inhibit the signaling of toll-like receptors can limit the presentation of auto-antigens, and inhibitors of apoptosis that extend the survival of effector cells can be blocked by antisense oligonucleotides. Mechanisms that enhance the clearance of apoptotic bodies and affect key signaling pathways are also feasible. Interventions that influence the survival of liver and effector cells by altering their apoptosis are candidates for study in autoimmune hepatitis.

Aberrant expression of the apoptosis-related proteins BAK and MCL1 in T cells in multiple sclerosis

Pathogenic T cells of multiple sclerosis (MS) patients have been suggested to be endowed with an increased resistance to apoptosis, contributing to their increased survival. We report herein increased levels of the anti-apoptotic MCL1 protein and its half-life in activated lymphocytes of MS patients, which were not associated with differences in MCL1 RNA levels or with alterations in the expression levels of the known E3 ligases of MCL1-β-TrCP and HUWE1. Concomitantly, the expression levels of the pro-apoptotic protein BAK were decreased in MS patients at relapse. These findings suggest the dysregulation of the apoptosis-related proteins MCL1 and BAK in MS.

New methods for multiple sclerosis drug discovery

INTRODUCTION

MS is a heterogeneous disorder that requires the development of better diagnostics to identify disease subtypes enabling appropriate therapeutic intervention at an early stage of the disease. Accumulating evidence indicates that members of the inhibitor of apoptosis (IAP) family play an important role in the pathogenesis of MS by reducing the apoptotic elimination of autoreactive immune cells.

AREAS COVERED

The authors describe improved animal modeling strategies to identify compounds that have immunomodulatory, neurorestorative and neuroprotective properties. In addition, the authors propose new approaches to better model cognitive dysfunction in MS, which will aid the development of novel therapeutics for this complex disorder. The paper provides the reader with an appreciation for the diagnostic and therapeutic potential of apoptosis-related proteins for MS.

EXPERT OPINION

Recent evidence suggests that increased resistance of autoreactive immune cells to apoptotic elimination is a contributing factor to both disease susceptibility and progression in MS. This occurs, at least in part, because of elevated levels of the IAP family of anti-apoptotic genes that display distinct expression profiles associated with different subtypes of MS. The authors believe that the detection and targeting of members of the IAP family can provide better drugs for MS. Particularly, the authors feel that the overexpression of IAPs in animal models can provide novel insights into MS for both its pathogenesis and the discovery of new lead compounds.

Xenobiotic exposure and autoimmune hepatitis

Although genetics contributes to the development of autoimmune diseases, it is clear that "environmental" factors are also required. These factors are thought to encompass exposure to certain drugs and environmental pollutants. This paper examines the mechanisms that normally maintain immune unresponsiveness in the liver and discusses how exposure to certain xenobiotics such as trichloroethylene may disrupt those mechanisms and promote autoimmune hepatitis.

Is the modulatory effect of pregnancy in multiple sclerosis associated with changes in blood apoptotic molecules?

OBJECTIVE

We examined whether the modulatory effect of pregnancy on multiple sclerosis (MS) is associated with changes in the apoptotic molecules in sera.

SUBJECTS AND METHODS

The serum levels of tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL), sFas, Fas ligand (sFasL) and macrophage migration inhibitory factor were analyzed from 19 MS patients and 14 controls during late pregnancy and post-partum. The obtained results were related to disease activity and the progression of MS.

RESULTS

Disease activity decreased during pregnancy. The levels of sTRAIL and sFasL increased from late pregnancy to post-partum situation in both MS patients and controls, but in MS patients the changes in the levels of sTRAIL from late pregnancy to post-partum were smaller than in controls.

CONCLUSIONS

Post-partum upregulation of TRAIL and FasL seems to be caused by physiologic reactivation of the mother's immune system after pregnancy. An increased risk of relapses in MS post-partum may be associated with changes in the immunomodulatory potential of these apoptotic molecules.

Fas activation increases neural progenitor cell survival

Although there is a sizable amount of research focusing on adult neural progenitor cells (NPCs) as a therapeutic approach for many neurodegenerative diseases, including multiple sclerosis, little is known about the pathways that govern NPC survival and apoptosis. Fas, a member of the death receptor superfamily, plays a well-characterized role in the immune system, but its function in neural stem cells remains uncertain. Our study focuses on the effects of Fas on NPC survival in vitro. Activation of Fas by recombinant Fas ligand (FasL) did not induce apoptosis in murine NPCs in culture. In fact, both an increase in the amount of viable cells and a decrease in apoptotic and dying cells were observed with FasL treatment. Our data indicate that FasL-mediated adult NPC neuroprotection is characterized by a reduction in apoptosis, but not increased proliferation. Further investigation of this effect revealed that the antiapoptotic effects of FasL are mediated by the up-regulation of Birc3, an inhibitor of apoptosis protein (IAP). Conversely, the observed effect is not the result of altered caspase activation or FLIP (Fas-associated death domain-like interleukin-1beta-converting enzyme inhibitory protein) up-regulation, which is known to inhibit caspase-8-mediated cell death in T cells. Our data indicate that murine adult NPCs are resistant to FasL-induced cell death. Activation of Fas increased cell survival by decreasing apoptosis through Birc3 up-regulation. These results describe a novel pathway involved in NPC survival.

Ability of trichloroethylene metabolite to promote immune pathology is strain-specific

Chronic low-level exposure to the environmental pollutant trichloroethylene has been shown to promote autoimmune disease in association with CD4(+) T-lymphocyte activation in lupus-prone MRL(+/+) mice. One of the primary metabolites of trichloroethylene, trichloroacetaldehyde hydrate (TCAH), was similarly shown to increase the percentage of IFNgamma-producing CD4(+) T-lymphocytes when added to the drinking water of MRL(+/+) mice. In addition, TCAH-treated MRL(+/+) mice developed skin inflammation and alopecia. In the present study TCAH was tested for its ability to accelerate the development of alopecia in C3H/HeJ mice which tend to develop the disorder spontaneously late in life. In contrast to MRL(+/+) mice, C3H/HeJ mice treated with TCAH did not develop alopecia at an increased rate. In addition, TCAH did not promote the expansion of activated IFNgamma-producing CD4(+) T-lymphocytes in C3H/HeJ mice. CD4(+) T-lymphocytes from TCAH-treated C3H/HeJ mice, unlike their MRL(+/+) counterparts, did not become resistant to activation-induced apoptosis following in vivo exposure to TCAH. Taken together, it appears that the ability of TCAH to promote immune-mediated pathology is strain-specific and may require an autoimmune-prone genetic background.

Clone clusters in autoreactive CD4 T-cell lines from probable multiple sclerosis patients form disease-characteristic signatures

We developed a method for selectively propagating disease-related autoreactive T-cell lines (auTCLs) based on their increased resistance to apoptosis. The generated auTCLs homogeneously co-express CD45RO and CD49a, adhere strongly to extracellular matrix proteins and express high interleukin-17 (IL-17) messenger RNA levels, resembling a T-cell subset proposed to transmigrate into tissues and induce systemic and local inflammation in rheumatoid arthritis. The combinations of T-cell oligoclones that comprise probable multiple sclerosis (pMS) disease-related lines use a unique portfolio of T-cell receptor beta-chain variable allele (BV genes) combinations forming 'disease-specific cluster patterns'. The auTCL derived from different patients and from different myelin epitopes display striking similarities in BV gene allele clusters and are derived primarily from a disease-prone hotspot residing in the BV gene locus between Vbeta6 and Vbeta9. Conversely, healthy subject TCLs use different BV gene allele sets, forming 'healthy responder usage formats'. These formats were absent from the pMS patient V-beta gene allele combinations evaluated in this study. Hierarchical clustering of the BV gene combinations, distinguish three pMS auTCL groups, implying existence of up to three disease-related immune response patterns. These subgroup patterns may reflect different disease subclasses or alternatively they may suggest immune reactivity to different aetiological agents. Analyses of clonal-clustering patterns may potentially aid in subclassification of MS or in characterizing aetiological agents of this disease.

Increased X-linked inhibitor of apoptosis protein (XIAP) expression exacerbates experimental autoimmune encephalomyelitis (EAE)

Dysregulated apoptotic signaling has been implicated in most forms of cancer and many autoimmune diseases, such as multiple sclerosis (MS). We have previously shown that the anti-apoptotic protein X-linked inhibitor of apoptosis (XIAP) is elevated in T cells from mice with experimental autoimmune encephalomyelitis (EAE). In MS and EAE, the failure of autoimmune cells to undergo apoptosis is thought to exacerbate clinical symptoms and contribute to disease progression and CNS tissue damage. Antisense-mediated knockdown of XIAP, in vivo, increases the susceptibility of effector T cells to apoptosis, thus attenuating CNS inflammation and thereby alleviating the clinical signs of EAE. We report for the first time, generation of transgenic mice whereby the ubiquitin promoter drives expression of XIAP (ubXIAP), resulting in increased XIAP expression in a variety of tissues, including cells comprising the immune system. Transgenic ubXIAP mice and wild-type (WT) littermates were immunized with myelin oligodendrocyte glycoprotein (MOG35-55) in complete Freund's adjuvant and monitored daily for clinical symptoms of EAE over a 21-day period. The severity of EAE was increased in ubXIAP mice relative to WT-littermates, suggesting that XIAP overexpression enhanced the resistance of T cells to apoptosis. Consistent with this finding, T cells derived from MOG35-55-immunized ubXIAP mice and cultured in the presence of antigen were more resistant to etoposide-mediated apoptosis compared to WT-littermates. This work identifies XIAP is an important apoptotic regulator in EAE and a potential pharmacological target for treating autoimmune diseases such as MS.

Diminished myelin-specific T cell activation associated with increase in CTLA4 and Fas molecules in multiple sclerosis patients treated with IFN-beta

Multiple sclerosis (MS) is a chronic inflammatory disease of the white matter of the central nervous system (CNS) characterized by focal areas of demyelination. Interferon-beta (IFN-beta) provides an effective treatment that lessens the frequency and severity of exacerbations in relapsing-remitting multiple sclerosis (RRMS), but the mechanisms by which IFN-beta is efficient remain uncertain. The data presented here demonstrate that IFN-beta impairs the proliferative response to myelin basic protein (MBP) and myelin, as well as increasing the expression of the CTLA4 intracellular molecule. Moreover, this treatment increases the expression of surface Fas molecules and of the soluble form of these molecules. Our hypothesis is that the increase in Fas and CTLA4 molecules in MS patients may lead to lymphocyte apoptosis, which suggests possible mechanisms underlying the therapeutic response to IFN-beta.

X-linked inhibitor of apoptosis regulates T cell effector function

To understand how the balance between pro- and anti-apoptotic signals influences effector function in the immune system, we studied the X-linked inhibitor of apoptosis (XIAP), an endogenous regulator of cellular apoptosis. Real-time PCR showed increased XIAP expression in blood of mice with experimental autoimmune encephalomyelitis, correlating with disease severity. Daily administration (10 mg/kg/day i.p.) of a 19-mer antisense oligonucleotide specific for XIAP (ASO-XIAP) abolished disease-associated XIAP mRNA and protein expression, and given from day of onset, alleviated experimental autoimmune encephalomyelitis and prevented relapses. Prophylactic treatment also reduced XIAP expression and prevented disease. Random or 5-base mismatched ASO was not inhibitory, and ASO-XIAP did not affect T cell priming. In ASO-XIAP-treated animals, infiltrating cells and inflammatory foci were dramatically reduced within the CNS. Flow cytometry showed an 88-93% reduction in T cells. The proportion of TUNEL(+) apoptotic CD4(+) T cells in the CNS was increased from <1.6 to 26% in ASO-XIAP-treated mice, and the proportion of Annexin V-positive CD4(+) T cells in the CNS increased. Neurons and oligodendrocytes were not affected; neither did apoptosis increase in liver, where XIAP knockdown also occurred. ASO-XIAP increased susceptibility of T cells to activation-induced apoptosis in vitro. Our results identify XIAP as a critical controller of apoptotic susceptibility of effector T cell function.

Inhibitor of apoptosis protein (IAP) profiling in experimental autoimmune encephalomyelitis (EAE) implicates increased XIAP in T lymphocytes

In multiple sclerosis (MS) and its widely accepted animal model, experimental autoimmune encephalomyelitis (EAE), the failure of autoreactive immune cells to undergo apoptosis is thought to contribute to CNS tissue damage and disease progression. Promoting apoptosis of myelin-reactive immune cells in diseases such as MS, may delay disease progression and decrease the frequency and severity of relapses. X-linked inhibitor of apoptosis (XIAP) is a potent anti-apoptotic protein that inhibits intrinsic, extrinsic, and c-Jun amino-terminal kinase mediated apoptosis and was the only member of the inhibitor of apoptosis (IAP) family upregulated in whole blood from EAE mice. Similar increases in XIAP were also observed in both peripheral and encephalitogenic T lymphocytes. Increased XIAP expression in T cells within areas of demyelination in the CNS suggests that XIAP may be enhancing cell survival and thereby contributing to disease pathology.

Detection of apoptotic cells in cerebrospinal fluid of patients suffering from neurological disease

Apoptotic elimination of pathogenic immune cells is considered one of several regulatory mechanisms in inflammatory diseases. To explore the potential relationship between detection of apoptotic cells in the cerebrospinal fluid (CSF) and different types of neurological diseases, we examined cellular apoptosis at the stage of DNA fragmentation, defined by morphological criteria and a molecular biology technique (in situ tailing). During a first phase, 3446 CSF samples derived from admitted patients suffering of inflammatory (IND) and non-inflammatory neurological diseases (NIND) were analysed in the course of routine clinical diagnostics. First, all specimens were inspected for cells displaying atypical morphology following established morphological criteria of intact lymphocytes or apoptosis. In a second phase, 76 additional CSF samples collected from individuals according to investigated clinical groups were analysed in parallel by means of in situ tailing, which indicates the advanced degree of apoptotic demise through labelling of controlled DNA fragmentation. No apoptotic processes were detected by either analytical method in CSF of clinically distinct diseases, amongst others multiple sclerosis (MS). This indicates that the detection of apoptotic cells in CSF during clinical routine diagnostics does not have sufficient explanatory power for the investigated conditions. Furthermore, based on immunohistochemistry, the proportion of CSF lymphocytes expressing the pro-apoptotic receptor Fas (CD95) tended to be higher in NIND patients compared to patients with other IND and MS, but the difference was not statistically significant. In contrast, expression of the anti-apoptotic protein Bcl-2 did not differ between investigated patient groups.

Impaired Expression of Peripheral Blood Apoptotic-Related Gene Transcripts in Acute Multiple Sclerosis Relapse

Differential expression of apoptotic genes may influence the susceptibility of activated lymphocytes to expand and induce acute relapse and persistent inflammation in patients with relapsing-remitting multiple sclerosis (RRMS). The exact relationship between alterations in apoptotic-related gene expression and clinical disease activity has not been broadly evaluated. In this study we studied peripheral blood mononuclear cells (PBMCs) expression of pro- and antiapoptotic genes in RRMS patients during acute relapse in comparison to patients in remission. Using cDNA Affymetrix microarrays platform (U133A2 microarrays) we analyzed the gene expression profile of PBMC derived from 22 RRMS patients in acute relapse (15 females, mean age 34.6 +/- 1.8 years, disease duration 5.6 +/- 0.8 years) in comparison to 20 sex- and age-matched RRMS patients in remission. One thousand five hundred seventy-eight gene transcripts significantly differentiated acute multiple sclerosis (MS) relapse from remission. This characteristic gene expression signature was enriched by an apoptotic-related pathway. The 1578 gene transcripts that significantly differentiated acute relapse from remission were enriched by 55 apoptotic-related genes in that reflected different operating pathways during the acute phase of the disease. These genes mainly involved the caspase-dependent pathway and included overexpression of the negative regulator of FAS-induced apoptosis (TOSO) and the BCL2 antiapoptotic family members (BCL2, BCL2 AA) as well as downexpression of proapoptotic genes like BAX, apoptotic protease-activating factor 1 (APAF1) and caspases 1, 2, 8, 9. and 10. An additional group of antiapoptotic genes related to T cell receptor-mediated apoptosis was also found to be overexpressed in acute relapse and included TCR-binding CD3E antigen, antiapoptotic serine threonin kinase (AKT), and NF kappa B-associated genes like reticuloendotheliosis viral oncogene homolog A (RELA) and human T cell leukemia virus type I-binding protein (Tax1BP) known to inhibit tumor necrosis factor (TNF)-induced apoptosis. Our findings demonstrate impaired apoptotic mechanisms in peripheral lymphocytes from RRMS patients during acute relapse. This suggests that the inflammatory process in active disease is targeted by inhibition of proapoptotic and repression of antiapoptotic genes that allow prolonged abnormal immune responses.

Impaired caspase-3 expression by peripheral T cells in chronic autoimmune thyroiditis and in autoimmune polyendocrine syndrome-2

CONTEXT

Activation-induced cell death (AICD) is a major mechanism in the regulation of peripheral tolerance, and caspase-3 represents its major executioner. AICD impairment contributes to the persistence of autoreactive T cells, and defective AICD has been reported in autoimmune thyroiditis as well as in type 1 diabetes mellitus.

OBJECTIVE

The objective of this study was to evaluate the involvement of caspase-3 in the regulation of AICD resistance in thyroid and polyendocrine autoimmunity. DESIGN/SETTINGS/PATIENTS/INTERVENTION: Caspase-3 expression was analyzed in peripheral blood lymphocytes from 26 adults (A-AT) and 25 children (Y-AT) affected by autoimmune thyroiditis and 13 individuals affected by chronic autoimmune thyroiditis plus Addison's disease [autoimmune polyendocrine syndrome-2 (APS-2)] in comparison with 32 age-matched normal control subjects (NC).

OUTCOME MEASURES

Caspase-3 mRNA expression in peripheral T cells was evaluated by quantitative real-time PCR; protein expression of both procaspase-3 and activated caspase-3 by Western blot analysis was followed by scanning densitometry.

RESULTS

Caspase-3 mRNA expression was significantly reduced in resting lymphocytes from both A-AT (P = 0.001) and Y-AT (P = 0.016) compared with NC. After lymphocyte activation, protein levels of caspase-3 active form were significantly reduced in A-AT (P = 0.023) and Y-AT (P = 0.001) compared with NC. The APS-2 group displayed characteristics similar to the A-AT group because both caspase-3 mRNA and protein active form levels were significantly reduced compared with NC (P = 0.004 and 0.002, respectively).

CONCLUSION

Our data show that peripheral lymphocytes of subjects affected by thyroid autoimmunity or APS-2 show defective expression of the major executioner of AICD, thus potentially contributing to AICD resistance and to the development of autoimmunity.

Exposure to a metabolite of the environmental toxicant, trichloroethylene, attenuates CD4+ T cell activation-induced cell death by metalloproteinase-dependent FasL shedding

Long-term exposure to the environmental contaminant trichloroethylene (TCE) in drinking water has been shown to promote autoimmune disease in association with the expansion of activated CD4+ T cells. The effects of TCE on CD4+ T cells were linked in the present study to the ability of TCE metabolite, trichloroacetaldehyde hydrate (TCAH), to inhibit activation-induced cell death (AICD) in CD4+ T cells. TCAH attenuated AICD in CD4+ T cells by decreasing FasL (CD178) expression but not by altering Fas (CD95) expression or by interfering with Fas-signaling events following direct engagement of the Fas receptor. The TCAH-induced decrease in FasL expression did not appear to be mediated at the transcriptional level but was instead due to increased shedding of FasL from the surface of the CD4+ T cells. The ability of TCAH to cleave FasL and thereby decrease AICD appeared to be mediated by metalloproteinases and correlated with a TCAH-induced increase in matrix metalloproteinase-7. Thus, this study presents the novel finding that the environmental contaminant TCE works via its metabolite TCAH to attenuate AICD by increasing metalloproteinase activity that cleaves FasL from CD4+ T cells. This represents a mechanism by which an environmental trigger inhibits AICD in CD4+ T cells and may thereby promote CD4+ T cell-mediated autoimmune disease.

Apoptosis of T cells in peripheral blood and cerebrospinal fluid is associated with disease activity of multiple sclerosis

Apoptotic elimination of pathogenic T cells is considered to be one of regulatory mechanisms in multiple sclerosis (MS). To explore the potential relationship between Fas-mediated apoptosis and the disease course of MS, we examined apoptosis, defined by annexin V (AV) binding, and Fas (CD95) expression in CD4+ and in CD8+ T cells in MS patients by using five-color flow cytometry. The percentage of AV+CD4+CD3+ cells and CD95+AV+CD4+CD3+ cells in peripheral blood and cerebrospinal fluid (CSF) were significantly decreased in active MS patients compared with inactive MS patients. A significantly lower proportion of CD95+AV+CD8+CD3+ cells in CSF was observed in active MS patients compared with inactive MS patients, but not in peripheral blood. These results indicate that the resistance of T cells to Fas-mediated apoptosis is involved in exacerbation of MS and/or that Fas-mediated apoptosis of T cells is associated with remission of MS.

Targeting endogenous inhibitors of apoptosis for treatment of cancer, stroke and multiple sclerosis

The inhibitor of apoptosis (IAP) genes have emerged as probably the most important intrinsic regulators of apoptosis. The members of the IAP family are highly conserved in evolutionarily distant species and perform the critical role of binding to and inhibiting distinct caspases. This inhibition is mediated by discrete baculoviral IAP repeat domains that, in a domain-specific manner, inhibit either the initiator or executioner caspases. As such the function of IAPs lies at the very centre of virtually all apoptotic pathways. Since many, if not most, human pathologies involve aberrant apoptosis, the modulation of IAP levels or their activity offers huge therapeutic potential for treatment of various disorders. Indeed, available data suggest that the therapeutic downregulation of IAPs by antisense targeting or their adenovirally-mediated overexpression, can in fact be used to successfully modulate cell death.

Detection of up-regulated genes in thrombin-stimulated human umbilical vein endothelial cells

INTRODUCTION

Thrombin, a serine protease, plays an important role in such actions as coagulation, cell proliferation and inflammation. It has been sporadically reported that endothelial cells, when stimulated by thrombin via protease-activated receptors (PAR), express various mediators and proteins including cytokines, chemokines, growth factors, and adhesion molecules. However, the pleiotropic effect of thrombin on endothelial cells has not yet been fully elucidated.

MATERIALS AND METHODS

We newly searched for the up-regulated genes in the thrombin-stimulated endothelial cells by thorough screening using a microarray chip, printed with 22,575 human genes, followed by verification using real-time PCR (n=3).

RESULTS AND CONCLUSIONS

Twelve genes, which were 4.8 times or more up-regulated in a microarray analysis, were selected and further analyzed. In real-time PCR, ICAM-1, IL-8, BIRC3, COL3A1, CXCL3, and CXCL1 were significantly up-regulated in the thrombin-stimulated cells: 16.0-, 8.81-, 5.92-, 3.74-, 1.74-, and 1.66-fold, respectively. VCAM-1, CXCL2, CCL20, CSF2, CD69, and CCL2 were up-regulated in the thrombin-stimulated cells: 12.2-, 2.44-, 1.90-, 1.82-, 1.62-, and 1.06-fold, respectively, without attaining statistical significance. We demonstrated, for the first time, that BIRC3 (anti-apoptotic protein), COL3A1 (matrix protein synthesis), and CXCL3 (chemokine) were up-regulated in the thrombin-stimulated HUVECs.

Programmed cell death of myelin basic protein-specific T lymphocytes is reduced in patients with acute multiple sclerosis

We investigated the apoptosis of myelin basic protein (MBP)-specific T lymphocytes in multiple sclerosis (MS) patients with acute (AMS) or stable (SMS) MS by evaluating the expression of apoptosis markers on peripheral cells. Cells of healthy controls (HC) were evaluated as well. Results showed that mitogen-stimulated apoptosis was comparable among patients and controls, whereas MBP-stimulated CD4+ and CD8+ 7-AAD+ and 7-AAD+ Fas+ cell (apoptotic cells) were significantly reduced in AMS patients. A reduction of the apoptotic rate of myelin-specific CD4+ and CD8+ T lymphocytes could be involved in the immune-mediated destruction of the myelin sheath seen in AMS patients.

Regulatory role of p53 in experimental autoimmune encephalomyelitis

The role of p53, a pro-apoptotic protein, in experimental autoimmune encephalomyelitis (EAE) was investigated using p53-deficient C57BL/6J mice. p53-deficient mice immunised with myelin oligodendrocyte glycoprotein (MOG) exhibited a more severe clinical course of EAE with more severe inflammation in the central nervous system (CNS) compared to wild-type littermates. While T and B cell responses of p53-deficient mice to MOG were comparable to those of wild-type littermates, significantly higher production of IL-6, granulocyte macrophage colony-stimulating factor and IL-10 was observed in lymphocytes exposed to MOG from p53-deficient mice than those from wild-type littermates. Furthermore, a flow cytometric analysis of Annexin V staining showed that apoptosis of CNS-infiltrating cells was less in p53-deficient mice with EAE compared to wild-type littermates. These results suggest that p53 may be involved in the regulatory process of EAE through the control of cytokine production and/or the apoptotic elimination of inflammatory cells.

Reduced expression of the inhibitor of apoptosis proteins in T cells from patients with multiple sclerosis following interferon-beta therapy

Treatment with interferon-beta reduces clinical exacerbations in multiple sclerosis (MS) through several immunomodulatory mechanisms that involve the augmentation of programmed cell death (apoptosis) of peripheral T lymphocytes. The recently identified family of inhibitor of apoptosis (IAP) proteins is a potent regulator of cell death. The expression of IAP-1, IAP-2, and X-linked IAP (XIAP) is upregulated in mitogen stimulated T lymphocytes from MS patients, and this expression correlates with MS disease activity. In this study, we sought to evaluate the effect of interferon-beta on cellular expression of IAP proteins and other apoptosis regulatory molecules. In a prospective study, we evaluated the expression of IAP proteins, the anti-apoptosis Bcl-2 protein, and the death receptor Fas in in vitro stimulated T lymphocytes from MS patients, before and serially after treatment with interferon-beta. We also investigated the long-term effects of interferon-beta on cellular expression of these proteins and T lymphocyte apoptosis in a cross-sectional study of MS patients receiving drug therapy for a mean of 4.8 years. Treatment with interferon-beta reduced the expression of IAP-1, IAP-2 and XIAP in stimulated T lymphocytes. This reduced expression correlated with increased T cell susceptibility to apoptosis and with clinical response to treatment. In contrast, interferon-beta therapy did not alter cellular expression of Bcl-2 protein or the death receptor Fas. This downregulatory effect of interferon-beta on cellular expression of IAP proteins was maintained following long-term therapy. Our findings suggest that interferon-beta therapy exerts a regulatory effect on peripheral T lymphocytes through an anti-apoptosis mechanism that involves the downregulation of cellular IAP proteins expression.