Abnormal Fas/FasL and caspase-3-mediated apoptotic signaling pathways of T lymphocyte subset in patients with systemic lupus erythematosus

CD4 T lymphocyte subsets display heterogeneous susceptibility to apoptosis induced by serum from patients with systemic lupus erythematosus

BACKGROUND

Serum from systemic lupus erythematosus (SLE) patients has been shown to induce T-lymphocyte (TL) apoptosis. Given that different cells of the immune system display different sensitivity to apoptosis, we set to evaluate the in vitro effect of SLE serum on regulatory T-cells (Treg), Th17, Th1 and Th2 from SLE patients and healthy controls.

METHODS

Peripheral blood mononuclear cells from SLE patients or normal controls were exposed to a pool of sera from SLE patients or normal controls. Annexin V was used to label cells in apoptosis or necrosis. Annexin V-labeled Treg, Th17, Th1 and Th2 cells were determined using flow cytometry.

RESULTS

Total CD3 + and CD4 + cells from SLE patients showed higher frequency of spontaneous apoptosis/necrosis, whereas Th1 cells from SLE patients presented reduced spontaneous apoptosis/necrosis rate as compared with cells from controls. Incubation with SLE serum induced increased frequency of apoptotic/necrotic CD3 + , CD4 + and Th2 cells from normal controls or from SLE patients as compared with cultures incubated with normal human serum (NHS) or without human serum at all. Incubation with SLE serum did not increase the apoptosis/necrosis rate in Th1 or Th17 cells. Treg cells from SLE patients were more prone to apoptosis/necrosis induced by SLE serum than Treg cells from normal individuals. Th1, Th2, and Th17 cells presented increased apoptosis rates in cultures without human serum.

CONCLUSION

Our findings indicate that the serum of patients with active SLE stimulates apoptosis of CD4 + T cells in general and exhibit differentiated effects on CD4 + T-cell subsets.

Ras family signaling pathway in immunopathogenesis of inflammatory rheumatic diseases

The Ras (rat sarcoma virus) is a GTP-binding protein that is considered one of the important members of the Ras-GTPase superfamily. The Ras involves several pathways in the cell that include proliferation, migration, survival, differentiation, and fibrosis. Abnormalities in the expression level and activation of the Ras family signaling pathway and its downstream kinases such as Raf/MEK/ERK1-2 contribute to the pathogenic mechanisms of rheumatic diseases including immune system dysregulation, inflammation, and fibrosis in systemic sclerosis (SSc); destruction and inflammation of synovial tissue in rheumatoid arthritis (RA); and autoantibody production and immune complexes formation in systemic lupus erythematosus (SLE); and enhance osteoblast differentiation and ossification during skeletal formation in ankylosing spondylitis (AS). In this review, the basic biology, signaling of Ras, and abnormalities in this pathway in rheumatic diseases including SSc, RA, AS, and SLE will be discussed.

Correlation between peripheral blood lymphocyte subpopulations and primary systemic lupus erythematosus

This study explored the correlation between peripheral blood CD3＋, CD3＋/CD4＋, CD3+/CD8+, CD4＋/CD8＋, CD3-/CD16+ CD56+, and CD3-CD19+ and disease activity of different subtypes of systemic lupus erythematosus (SLE). The percentages of CD3+, CD3+/CD4+, CD3+/CD8+, CD4+/CD8+, CD3-/CD16+ CD56+, and CD3-CD19+ in the peripheral blood of patients (n = 80) classified into lupus nephritis, blood involvement, and joint involvement and SLE in different active stages were detected by flow cytometry. Their correlations with baseline clinical experimental indicators of SLE patients' SLE disease activity index score (SLEDAI) and complement C3 were analyzed. The results showed that CD3+, CD3+/CD4+, and CD3+/CD8+ at baseline level were negatively correlated with SLEDAI scores. These were positively correlated with C3. In conclusion, T-lymphocyte subpopulations are closely related to SLE activity and can be used as reference indicators to evaluate the SLE activity.

Down-regulated ALKBH5 Expression Could Affect the Function of T Cells in Systemic Lupus Erythematosus Patients

BACKGROUND

N6-methyladenosine (m6A) modification is widespread in eukaryotic mRNA, regulated by m6A demethylase, AlkB homolog 5 (ALKBH5). However, the role of m6A in systemic lupus erythematosus (SLE) is still obscure. We explored ALKBH5 expression in SLE patients and its effects on T cells.

METHODS

100 SLE patients and 110 healthy controls were recruited to investigate the expression of ALKBH5 in peripheral blood mononuclear cells (PBMCs). An additional 32 SLE patients and 32 health controls were enrolled to explore the expression of ALKBH5 in T cells. Then we explored the function of ALKBH5 in T cells by lentivirus.

RESULTS

The expressions of ALKBH5 were downregulated in both PBMCs and T cells in SLE patients (all P<0.05). In PBMCs: ALKBH5 mRNA levels were associated with complement C4 level in plasma (P<0.05). In T cells: ALKBH5 mRNA levels were downregulated in SLE patients with low complement levels, high anti-dsDNA, anti-Sm, anti-RNP, and proteinuria compared with those without, respectively (all P<0.05); ALKBH5 mRNA levels were negatively related with SLE disease activity index score, erythrocyte sedimentation rate, and anti-dsDNA levels (all P<0.05), and positively correlated with complement C3 and C4 level (all P<0.05). Functionally, the overexpression of ALKBH5 promoted apoptosis and inhibited the proliferation of T cells (all P<0.05).

CONCLUSION

ALKBH5 expression is downregulated in SLE patients and could affect the apoptosis and proliferation of T cells, but the exact mechanism still needs to be further explored.

Regulation of activated T cell survival in rheumatic autoimmune diseases

Adaptive immune responses rely on the proliferation of T lymphocytes able to recognize and eliminate pathogens. The magnitude and duration of the expansion of activated T cell clones are finely regulated to minimize immunopathology and avoid autoimmunity. In patients with rheumatic autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis, activated lymphocytes survive and exert effector functions for prolonged periods, defying the mechanisms that normally curb their capacities during acute and chronic infections. Here, we review the molecular mechanisms that limit the duration of immune responses in health and discuss the factors that alter such regulation in the setting of systemic lupus erythematosus and rheumatoid arthritis. We highlight defects that could contribute to the development and progression of autoimmune disease and describe how chronic inflammation can alter the regulation of activated lymphocyte survival, promoting its perpetuation. These concepts might contribute to the understanding of the mechanisms that underlie the chronicity of inflammation in the context of autoimmunity.

Expression Pattern of Telomerase Reverse Transcriptase (hTERT) Variants and Bcl-2 in Peripheral Lymphocytes of Systemic Lupus Erythematosus Patients

Background & Objective:

It is not clear whether activated lymphocytes of patients with systemic lupus erythematosus (SLE) are more proliferative or less apoptotic. We aimed to delineate potential differences between B and T cells of SLE patients compared to healthy controls regarding the telomerase activity and apoptosis status.

Methods:

In this cross-sectional case control study, Blood samples were taken from 10 SLE patients and 10 healthy controls. B and T cells were separated using magnetic cell sorting system. Telomeric repeat amplification protocol (TRAP) assay and real-time PCR were used to determine the telomerase activity and the expression of alternatively spliced variants.

Results:

Four patients under treatment showed significant telomerase activity in their T cells. Four of the newly diagnosed patients showed telomerase activity in their B cells (20% of all patients and 40% of new onset patients). There was no specific pattern of human telomerase reverse transcriptase variant expression within the patients’ lymphocytes. A significantly reduced expression of Bcl-2 was detected in B cells (P=0.018) and a trend toward lower Bcl-2 expression in T cells was seen in SLE patients compared to healthy controls.

Conclusion:

Although not definitive, our results may suggest that B cells may have more active roles during the earlier phases of the disease attack, while T cells take over when the disease reaches its chronic stages.

[Total glucosides of paeony inhibits proliferation and promotes activation- induced cell death of mouse T cells in vitro]

OBJECTIVE

To investigate the effects of total glucosides of paeony (TGP) on the proliferation and activation-induced cell death of mouse T cells and the mechanism underlying the immunosuppressive effects of TGP.

METHODS

Purified total T cells isolated from the spleen of C57BL/6 mice were treated with TGP at 0, 50, 100, or 200 μg/mL and stimulated by anti-CD3/ CD28. Flow cytometry was performed to detect the cell death and the proliferation of CFSE-labeled T cells. The expression of Fas/FasL mRNA was detected using RT-PCR, and flow cytometry was used to analyze the expression of Fas/FasL proteins on activated T cells. Western blotting was used to detect the expression of Bcl-2 in the cells.

RESULTS

TGP treatment for 48 h significantly reduced the total number and percentage of viable T cells and dose-dependently lowered the percentage of divided T cells. TGP treatment obviously up-regulated the cellular expression of Fas mRNA, enhanced Fas expression on the surface of the T cells, and decreased the expression level of Bcl-2 protein in the cells.

CONCLUSIONS

TGP significantly inhibits proliferation and promotes activation-induced cell death of mouse T cell by increasing the expression of Fas and downregulating the expression of Bcl-2.

Altered peripheral lymphocyte subsets in untreated systemic lupus erythematosus patients with infections

The leading cause of death in systemic lupus erythematosus (SLE) patients is infection. The objective of this study was to evaluate the distribution of lymphocyte subsets in untreated SLE patients with infections. This was a cross-sectional study. Data from January 2017 to May 2018 were collected. Flow cytometry was used to measure the peripheral lymphocyte subsets including CD3+T cells, CD4+T cells, CD8+T cells, CD19+B cells, CD3-CD16+CD56NK cells, and CD3+CD16+CD56NKT cells in 25 healthy controls and 52 treatment-naive SLE patients, among whom 13 were complicated with infections. Association between the lymphocyte subsets and infections was further analyzed. SLE patients with infections (n=13) showed a significantly higher incidence rate of fever (84.6 vs 28.2%) and serositis (84.6 vs 23.1%), increased level of erythrocyte sedimentation rate (60.5±30.1 vs 37.4±27.1 mm/h), serum C-reactive protein (CRP) (102.7±94.9 vs 9.4±14.9 mg/L), procalcitonin (PCT) (1.07±0.08 vs 0.16±0.13 μg/L), and lower blood hemoglobin (Hb) (93.0±20.5 vs 110.4±16.0 g/L) level compared with non-infection patients (n=39) (all P<0.05). In comparison with non-infectious SLE patients (387.9±261.6/μL), CD4+T cells count decreased significantly in infectious SLE patients (217.8±150.4/μL) (P<0.05), and it was negatively correlated with infection-related indicators including PCT (r=-0.573, P=0.041) and CRP (r=-0.596, P=0.032) levels. Our findings suggested that abnormalities of peripheral lymphocyte subsets were related to the immune disorder of lupus itself, regardless of immunosuppressive treatment. Monitoring lymphocyte subsets, especially CD4+T cells, may be helpful for identifying the presence of infection in SLE patients.

Role of MiR-98 and Its Underlying Mechanisms in Systemic Lupus Erythematosus

Objective.

T-lymphocyte apoptosis plays a critical role in the pathogenesis of systemic lupus erythematosus (SLE). However, the underlying regulatory mechanisms of apoptosis in SLE remain unclear. The aim of this study was to explore the role of miR-98 in SLE and its underlying mechanisms.

Methods.

Western blotting and quantitative reverse transcription PCR (qRT-PCR) were used to analyze miR-98 and Fas expression. Luciferase reporter assays were performed to identify miR-98 targets. To modify miRNA levels, miR-98 mimics and inhibitor were transfected into cells. A lentiviral construct was used to overexpress the level of Fas in SLE CD4+ T cells. Gene and protein expression were determined by qRT-PCR and Western blotting. Apoptosis levels were evaluated by annexin V staining and flow cytometry.

Results.

Compared to those of healthy donors, miR-98 was downregulated in SLE CD4+ T cells, whereas Fas mRNA and protein expression were upregulated. Upregulation of miR-98 by mimic transfection protected Jurkat cells against Fas-mediated apoptosis at both mRNA and protein levels, while miR-98 inhibitor induced the completely opposite effect. Luciferase reporter assays demonstrated that miR-98 directly targeted Fas mRNA. Further, miR-98 inhibitor induced apoptosis in primary healthy CD4+ T cells through the Fas-caspase axis, while upregulation of miR-98 in SLE CD4+ T cells led to the opposite effect.

Conclusion.

The current study revealed that downregulation of miR-98 induces apoptosis by modulating the Fas-mediated apoptotic signaling pathway in SLE CD4+ T cells. These results suggest that miR-98 might serve as a potential target for SLE treatment.

Evaluation of polymorphic variants in apoptotic genes and their role in susceptibility and clinical progression to systemic lupus erythematosus

Background Systemic lupus erythematosus (SLE) is an autoimmune disease marked by the disruption of the immune homeostasis. Patients exhibit a wide range of clinical manifestations, and environmental and genetic factors are involved in SLE pathogenesis. Evidence suggests that abnormalities in the cellular and molecular events that coordinate apoptosis may favour the generation of autoantigens involved in autoimmunity. In this way, the apoptotic deregulation may be affected by polymorphic variants in apoptotic-related genes. Methods We analyzed FAS, FASL, BCL-2 and BAX polymorphisms in order to correlate to SLE susceptibility and clinical features. A total of 427 SLE patients from the Hospital de Clínicas de Porto Alegre and 543 controls from southern Brazil were evaluated. Results We observed higher frequencies of the FASL -844CC genotype and -844C allele, as well as of the FASL-844C/IVS2nt-124A haplotype in African-derived SLE patients when compared to controls ( P < 0.001). FASL -844C, which is related to high FasL expression, could contribute to increased apoptosis and to the breakdown of immunological tolerance, favouring autoantibody production and inflammation. On the other hand, the BAX -248GA genotype and the -248A allele , related to low protein expression, were observed as a protective factor against SLE in this same population. The rate of apoptosis and cell death was evaluated in peripheral lymphocytes, and SLE patients presented a higher percentage of dead lymphocytes (CD3⁺Annexin V⁺ 7-AAD⁺) compared to the control group. Conclusion Our data support a role for apoptosis in SLE susceptibility.

Elevated levels of TRAIL in systemic lupus erythematosus are associated to the presence of anti-SSA/SSB antibodies

The objective of this study was to determine potential relationship between the levels of serum TNF-related apoptosis inducing ligand (TRAIL) and osteoprotegerin (OPG) and clinical markers in systemic lupus erythematosus (SLE) patients. Forty SLE patients with inactive disease were enrolled in this study. For comparison, 20 Sjögren's syndrome (SS) patients and 30 normal controls were also analysed. Serum levels of TRAIL and OPG were determined by ELISA. Serum TRAIL and OPG concentrations in SLE patients were significantly ( P < 0.05) higher than those in healthy volunteers. Of note, serum TRAIL but not OPG was significantly ( P < 0.05) higher in the SLE patient subset characterized by the presence of anti-SSA/SSB antibodies. The relationship between high levels of TRAIL and SSA/SSB antibodies was further supported by the analysis of SS patients characterized by SSA/SSB antibodies positivity, in which TRAIL levels resulted comparable to the subgroup of anti-SSA/SSB positive SLE patients. The presence of SSA/SSB antibodies, targeting a specific subset of SLE and SS patients, is related to increased serum levels of TRAIL but not of OPG. Lupus (2007) 16, 479—482.

Analysis of CD95 and CCR7 expression on circulating CD4(+) lymphocytes revealed disparate immunoregulatory potentials in systemic lupus erythematosus

Emerging data have implicated a critical role for CD4 in the pathogenesis of systemic lupus erythematosus (SLE). This study was designed to delineate the contribution of CD4(+) T cells in the pathogenesis of SLE disease. Forty-four patients (3 male: 41 female) and 20 healthy volunteers (4 male: 16 female) were included in the study. CD4(+) lymphocytes analysis was done using three-color flow cytometry with antibodies against human-CD95, a prototype cell death receptor, and the chemokine receptor-7 (CCR7) after gating for lymphocytes based on the forward and side scatter. Serum levels of IL-6, IL-12, IL-17, TNF-α and IL-10 cytokines were assayed using ELISA. Disease activity was assessed using the SLE disease activity index (SLEDAI). Based on the expression of CCR7 and CD95, CD4(+) lymphocytes were subdivided into three particular subsets; CD4(+)CD95(+)CCR7(+) cells, CD4(+)CD95(-)CCR7(+) cells and CD4(+)CD95(+)CCR7(-) cells. Percentage of CD4(+)CD95(+)CCR7(+) cell subset was significantly higher in patients with SLE with active disease (SLEDAI > 6) and inactive (SLEDAI < 6) as compared with controls (P = 0.005), and it showed a significant positive correlation with ANA titer (P = 0.01), and a negative correlation with WBCs count (P = 0.001). CD4(+)CD95(+)CCR7(-) cell subset was significantly higher in active SLE patients in comparison to patients with inactive disease and controls (P = 0.05, P = 0.005 respectively), and it correlates positively with SLEDAI, IL-6 and IL-17 levels (P = 0.001, 0.05, 0.01 respectively), and negatively with blood WBCs counts (P = 0.001). The third CD4(+)CD95(-)CCR7(+)cell subset was found significantly lower in SLE patients compared with controls, and it was found negatively correlated with IL-10, IL-6, and IL-17. The results show that CD4(+)CD95(+)subset lacking expression of CCR7 is associated with cell mediated inflammatory response as manifested by its correlation with signs of inflammation, inflammatory cytokines and disease activity index. Whereas, CD4(+)CD95(+)CCR7(+) correlate more with antibody immune responses as manifested by association with serum ANA. These data suggest disparate roles of these cell subsets in the pathophysiology of SLE. A better understanding of the characteristics of CD4 cell subsets may shed light on the pathogenesis of autoimmune diseases, particularly SLE.

Role of altered mitochondria functions in the pathogenesis of systemic lupus erythematosus

Mitochondria, main producers of reactive-oxygen species (ROS), were studied to examine their role in the pathogenesis of systemic lupus erythematosus (SLE). PBMCs and mitochondria were isolated from SLE patients and healthy volunteers for various parameters. Mitochondrial ROS, swelling, hyperpolarization and levels of cytochrome c, caspase3 in the cells were assessed by flow cytometry. ROS was significantly increased in SLE patients (SLE vs controls: 1.83 ± 1.03 vs 1.10 ± 0.35; p < 0.0001). Depolarized state of mitochondria was greater in patients (SLE vs controls: 7.10 ± 5.50% vs 2.5 ± 1.8%; p < 0.05). Mitochondria swelling was found to be significantly altered in patients (SLE vs controls: 112.65 ± 36.56 vs 60.49 ± 20.69; p < 0.001). Expression of cytochrome c and caspase 3 (SLE vs controls: 1.37 ± 0.37% vs 1.01 ± 0.03%; 1.57 ± 0.46% vs 1.06 ± 0.07%; p < 0.05) respectively was found to be significantly increased in SLE. Further, the enzymatic activity of mitochondrial complex was assessed in isolated mitochondria. A significant decrease in activity of Complex I (SLE vs controls: 11.79 ± 3.18 vs 15.10 ± 6.38 nmol NADH oxidized/min/mg protein, p < 0.05); Complex IV (SLE vs control: 9.41 ± 5.16 vs 13.56 ± 5.92 nmol cytochrome c oxidized/min/mg protein, p < 0.05) and Complex V (SLE vs controls: 4.85 ± 1.39 vs 6.17 ± 2.02 nmol ATP hydrolyzed/min/mg protein, p < 0.05) was found in SLE patients in comparison to healthy controls. However, Complex II did not show significant variation in either group (SLE vs controls: 42.2 ± 28.6 vs 61.71 ± 42.3 nmol succinate oxidized/min/mg protein; ns). The decrease in enzyme activities of mitochondrial Complexes I, IV and V on one hand and ROS, hyperpolarization and apoptosis on the other points toward a possible role of mitochondria in the pathogenesis of lupus.

Increased Tim-3 expression on peripheral T lymphocyte subsets and association with higher disease activity in systemic lupus erythematosus

Background

Both the T cell immunoglobulin domain- and mucin domain-containing molecule-3 (Tim-3) and the death receptor Fas contribute to the pathogenesis of various autoimmune diseases, including systemic lupus erythematosus (SLE). The aim of the present study was to determine whether Tim-3 and Fas are co-expressed on certain peripheral T lymphocyte subsets, and whether this expression is associated with greater disease activity in SLE.

Methods

Peripheral blood mononuclear cells were isolated from 46 patients newly diagnosed with SLE and 28 age- and sex-matched healthy controls (HCs). Expression of Tim-3 and Fas on T subsets was analyzed by flow cytometry, while mRNA levels of the Tim-3 ligand galectin-9 and Fas ligand FasL were assayed using real-time RT-PCR.

Results

The proportions of CD3⁺CD4⁺ and CD3⁺CD4^- T cells expressing Tim-3⁺ and Tim⁺Fas⁺ were significantly higher in patients than in HCs (p < 0.05), while the proportions of these subtypes expressing Fas were similar for the two groups. Patients with active SLE, as defined by their score on the SLE Disease Activity Index, had lower proportions of CD3⁺CD4⁺ T cells and higher proportions of CD3⁺CD4⁺Tim-3⁺ and CD3⁺CD4⁺Tim-3⁺Fas⁺ T cells than did patients with stable SLE. Serum levels of complement C3 and C4 proteins, considered as a marker of SLE activity, correlated negatively with proportions of CD3⁺CD4⁺ and CD3⁺CD4^- T cells expressing Tim-3.

Conclusions

Expression of Tim-3 and co-expression of Tim-3 and Fas on certain peripheral T subsets are associated with disease activity in SLE patients. Future research should examine whether the same is true of other T subsets implicated in SLE, and should explore the potential role(s) of Tim-3 in the disease pathway.

Virtual slides

http://www.diagnosticpathology.diagnomx.eu/vs/1855527845145188

Increased serum IL-10 in lupus patients promotes apoptosis of T cell subsets via the caspase 8 pathway initiated by Fas signaling

We sought to investigate the expression of Fas and FasL on T cell surface and caspase 8 involvement in T cell apoptosis promoted by serum IL-10 in systemic lupus erythematosus (SLE) patients. Cells and sera were obtained from 35 SLE patients. Apoptosis of T cells in patients with SLE was increased and associated with the SLE disease activity index (SLEDAI). Elevated expression of Fas and FasL on T cell surface contributed to increased apoptosis of T cells. Increased IL-10 in the sera of SLE patients was capable of inducing Fas and FasL expression on CD4⁺T cell surface, promoting apoptosis of this cell subset. Decreased IL-10 serum levels and low expression of Fas were found in 5 patients of the first follow-up group after 2-month treatment. In another group with one-year treatment, the SLEDAI declined to inactive scores. Serum IL-10 was decreased significantly, and expression of Fas and FasL on T cells was also reduced. Declined apoptosis was predominant only in CD4⁺T cell subset. When sera with high level of IL-10 were used to culture PBMCs from healthy controls, activated caspase 8 was elevated in CD3⁺T, CD4⁺T and CD8⁺T cells. The study showed that serum IL-10 induced apoptosis of T cell subsets via the caspase 8 pathway initiated by Fas signaling. Increased apoptosis of T cells contributes to autoantigen burden, which is pathogenic in the development of SLE.

The effect of esculentoside A on lupus nephritis-prone BXSB mice

INTRODUCTION

EsA was reported to have the effect of modulating immune response, cell proliferation and apoptosis as well as anti-inflammatory effects in acute and chronic experimental models. However, the effects of EsA on LN remain poorly understood. To investigate the roles of EsA in LN, the effects of EsA were tested on BXSB mice, a SLE model, in which male SB/Le mice and female C57BL/6 mice were hybridized through recombinant inbred species.

MATERIAL AND METHODS

Twenty four BXSB mice were divided into three groups. After 4 weeks, blood samples, urine samples and kidney tissues were collected. Measurement of cytokine levels was carried out using sandwich ELISA reagent kits. Apoptotic scores were obtained with a TUNEL assay. PCNA and Caspase-3 mRNA was detected using the In Situ Hybridization Detection Kit.

RESULTS

The results demonstrated that compared with the control group, EsA administration markedly controlled urine protein excretion, improved renal function, alleviated kidney damage and promoted the apoptosis of glomerular intrinsic cells and renal tubular epithelial cells in animals of the treated group (p < 0.05). Meanwhile, EsA reduced the serum IL-6 and TNF-α levels (p < 0.05), inhibited the expression of PCNA and promoted the expression of caspase-3, Fas and FasL in animals of the treated group (p < 0.05). The effects of EsA on BXSB mice were similar to dexamethasone.

CONCLUSIONS

All these findings indicated that EsA might play significant roles in the treatment of BXSB mice through modulation of inflammatory cytokines, inhibition of renal cell proliferation and induction of apoptosis. The special targets of EsA in lupus nephritis are worth further exploration.

Interaction between glutathione and apoptosis in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by imbalance redox state and increased apoptosis. The activation, proliferation and cell death of lymphocytes are dependent on intracellular levels of glutathione and controlled production of reactive oxygen species (ROS). Changes in the intracellular redox environment of cells, through oxygen-derived free radical production known as oxidative stress, have been reported to be critical for cellular immune dysfunction, activation of apoptotic enzymes and apoptosis. The shift in the cellular GSH-to-GSSG redox balance in favor of the oxidized species, GSSG, constitutes an important signal that can decide the fate of the abnormal apoptosis in the disease. The current review will focus on four main areas: (1) general description of oxidative stress markers in SLE, (2) alteration of redox state and complication of disease, (3) role of redox mechanisms in the initiation and execution phases of apoptosis, and (4) intracellular glutathione and its checkpoints with lymphocyte apoptosis which represent novel targets for pharmacological intervention in SLE.

Emerging and critical issues in the pathogenesis of lupus

Systemic lupus erythematosus (SLE) is a multisystemic, autoimmune disease, encompassing either mild or severe manifestations. SLE was originally labeled as being an immune complex-mediated disease, but further knowledge suggested its pathogenesis is motlier than that, involving complex interactions between predisposed individuals and their environment. People affected with SLE have their immune system skewed toward aberrant self-recognition usually after encountering a triggering agent. Defeats in early and late immune checkpoints contribute to tolerance breakdown and further generation and expansion of autoreactive cell-clones. B and T cells play a master role in SLE, however clues are emerging about other cell types and new light is being shed on SLE autoantibodies, since some of them display really harmful potential (pathogenic antibodies), while others are just connected with disease development (pathological antibodies) and may even be protective. Autoantibody generation is elicited by abnormal apoptosis and inefficient clearance of cellular debris causing intracellular autoantigens (e.g. nucleosomes) to persist in the extracellular environment, being further recognized by autoreactive cells. Here we explore the complexity of SLE pathogenesis through five core issues, i.e. genetic predisposition, B and T cell abnormalities, abnormal autoantigen availability, autoantibody generation and organ damage, relying on current knowledge and recent insights into SLE development.

Altered redox state and apoptosis in the pathogenesis of systemic lupus erythematosus

An altered redox status and increased lymphocyte apoptosis have been implicated in the development of systemic lupus erythematosus (SLE). In this study, we evaluated the relationship between glutathione (GSH) depletion, reactive oxygen species (ROS) and, the progression of apoptosis and their association with SLE severity. Significant low levels of intracellular glutathione, total thiol and altered redox state (GSH/GSSG) were found in SLE patients, in which lymphocyte apoptosis and activated caspase-3 expression in the lymphocytes were remarkably increased. The severity of disease was positively allied with the increased levels of lymphocyte apoptosis and caspase-3, but negatively with the decreased levels of total thiol, depleted intracellular glutathione and altered redox state (GSH/GSSG). The lymphocyte apoptosis and activated caspase-3 expression were negatively associated with intracellular levels of GSH and redox state and positively associated with the elevated levels of multiple oxidative stress markers; ROS and lipid peroxidation measured as malondialdehyde (MDA). These results suggest that GSH depletion and elevated oxidative stress trigger apoptosis and may be coupled with the severity of the disease.

Expression and prognostic value of FAS receptor/FAS ligand and TrailR1/TrailR2 in acute myeloid leukemia

We studied the expressions of FR, FL, TR1, and TR2 on blasts and T cells from 71 patients with acute myeloid leukemia (AML) and correlated expression rates with the clinical course. Compared to AML-blasts we found higher co-expressions on healthy myeloid and T cells. Expression of all markers on blasts and on T cells was similar in different subtypes and acute stages of AML. Compared to the non-responders (n = 7) responders to the AML Cooperative Group-therapy (n = 22) presented with higher proportions of blasts co-expressing the four markers (FR: 32 vs 15%; FL: 15 vs 13%; TR1: 72 vs 37%; TR2: 24 vs 23%) or T cells (FR: 88 vs 71%; FL: 76 vs 56%; TR1: 96 vs 44%; TR2: 54 vs 42%). Patients with higher expression rates of TR1 on blasts (≥ 48%) and on T cells (≥ 67%) were characterized by a prolonged survival. In summary, our data show a variable expression of FR, FL, TR1 and TR2 on blasts or T cells in different subgroups of AML. Higher co-expression rates of FR, FL, TR1 and TR2 were characterized by a better prognosis for the patients with respect to achieve a remission and to survive. Functional analyses should be performed to find out those patients in who induced upregulation of these markers could contribute to overcome drug resistance.

The pathway of estradiol-induced apoptosis in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a disease with unknown etiology. The pathologic role of sex hormones and apoptosis in SLE has often been discussed. We studied the effects of estradiol in the pathway of induced apoptosis in Iranian SLE patients. T lymphocytes from 35 SLE patients and 20 age-matched controls were isolated and cultured in the presence of 10(-8) M 17-β estradiol. The expression levels of Fas, Fas ligand (FasL), Bcl-2, caspase-8, and caspase-9 mRNAs were determined semiquantitatively in comparison to the expression level of beta actin RNA. Estradiol exposure did not have any significant effects on the expression levels of Fas, Bcl-2, and caspase-9 in SLE patients and controls. However, the expression levels of FasL and caspase-8 were significantly increased in SLE patients, but not in controls. This suggests the probable involvement of extrinsic apoptosis pathway in estradiol-induced apoptosis in SLE.

Induction of PP2A Bβ, a regulator of IL-2 deprivation-induced T-cell apoptosis, is deficient in systemic lupus erythematosus

The activity and substrate specificity of the ubiquitously expressed phosphatase PP2A is determined by the type of regulatory (B) subunit that couples to the catalytic/scaffold core of the enzyme. We determined that the Bβ subunit (PPP2R2B) is expressed in resting T cells, its transcription is down-regulated during T-cell activation, and up-regulated in conditions of low IL-2. Specifically, high levels of PP2A Bβ were produced during IL-2 deprivation-induced apoptosis, whereas Fas ligation had no effect. Forced expression of the Bβ subunit in primary human T cells was sufficient to induce apoptosis, whereas silencing using siRNA protected activated T cells from IL-2 withdrawal-induced cell death. Because T-cell apoptosis is known to be altered in T cells from patients with systemic lupus erythematosus, we analyzed the regulation of PP2A Bβ in this autoimmune disease. We found that levels of PP2A Bβ did not increase upon IL-2 deprivation in 50% of the patients. Remarkably, this defect was accompanied by resistance to apoptosis. Importantly, kinetics of cell death were normal in cells of patients that up-regulated PP2A Bβ in a normal manner. We have identified a unique role for the phosphatase PP2A, particularly the holoenzyme formed by PP2A Bβ. Bβ appears to trigger apoptosis of T cells in the absence of IL-2 and probably contributes to the termination of a no-longer-needed immune response. We propose that defective production of PP2A Bβ upon IL-2 deprivation results in apoptosis resistance and longer survival of autoreactive T cells, in a subset of SLE patients.

Association between T lymphocyte sub-sets apoptosis and peripheral blood mononuclear cells oxidative stress in systemic lupus erythematosus

Increased oxidative stress and lymphocyte apoptosis are a hallmark of the autoimmune disease systemic lupus erythematosus (SLE). However, the association between oxidative stress and T lymphocytes apoptosis has still to be elucidated in SLE. In order to appraise the interaction between oxidative stress and T lymphocyte apoptosis with the severity of disease, oxidative stress profile and T lymphocytes apoptosis were studied. Increased levels of ROS, MDA and CD4(+) lymphocyte apoptosis were positively associated with disease activity while decreased levels of GSH and percentage expression of CD4(+) lymphocyte were negatively associated with disease activity. The decrease in intracellular levels of GSH was negatively associated with T lymphocyte, CD4(+) lymphocyte, CD8(+) lymphocyte apoptosis and intracellular caspase-3 expression. The present study suggests that increased T lymphocyte sub-sets apoptosis may be mediated by decreased intracellular glutathione concentration and severity of disease might be enhanced together by over-production of ROS in SLE.

(S)-armepavine from Chinese medicine improves experimental autoimmune crescentic glomerulonephritis

OBJECTIVE

Intra-renal T cells and macrophages play a key pathogenic role in the development and progression of glomerular crescents. We aimed to establish (S)-armepavine [(S)-ARM], a major bioactive compound of a Chinese medicinal plant, Nelumbo nucifera, as a potential therapeutic agent in the treatment of autoimmune crescentic glomerulonephritis (ACGN).

METHODS

A mouse ACGN model associated with T-cell dysregulation, was used to evaluate the therapeutic effects of (S)-ARM on the rapidly progressive glomerular disorder.

RESULTS

The results showed that (S)-ARM administered in the established phase of ACGN is capable of dramatically decreasing glomerular crescents in the kidney and improving proteinuria and renal dysfunction. These effects were associated with greatly inhibited infiltration of T cells/macrophages and suppressed nuclear factor (NF)-κB activation in the kidney, lowered serum levels of autoantibodies and both serum and intra-renal levels of pro-inflammatory cytokines, suppressed T/B-cell activation and T-cell proliferation of the spleen, reduced glomerular immune deposits and apoptosis in both the spleen and kidney in (S)-ARM-treated ACGN mice, compared with the vehicle-treated (disease control) group of ACGN mice.

CONCLUSION

We demonstrated therapeutic effects of (S)-ARM on ACGN as a result of: (i) early systemic negative modulation of T/B cells; (ii) intra-renal regulation of combined NF-κB activation and mononuclear leucocytic infiltration, thereby preventing glomerular crescent formation; and (iii) protection from apoptosis in both the spleen and kidney.

Increased T-lymphocyte apoptosis in lupus correlates with disease activity and may be responsible for reduced T-cell frequency: a cross-sectional and longitudinal study

Apoptosis of lymphocytes is increased in patients with lupus. This may be pathogenic leading to increased load of autoantigens or may be a bystander effect of immune activation. A major unresolved issue is whether apoptosis is related to disease activity. Also its association with lymphocyte frequencies, anti-nucleosomal antibodies and serum IL 10 levels needs to be explored further. The aims of this study are to measure T- and B-lymphocyte apoptosis in patients with lupus and look at the effect of disease activity in a cross-sectional and longitudinal design and to determine frequency of T and B cells, level of anti-nucleosomal antibodies and serum IL 10 and assess their relationship with apoptosis. This study included 41 patients with SLE and 20 controls. A cutoff value of 4 in systemic lupus erythematosus disease activity index (SLEDAI) was used to separate active from inactive SLE. The frequency and degree of apoptosis of T and B lymphocyte were enumerated by flow cytometry using peripheral blood mononuclear cells (PBMCs) stained with CD3/CD19 and annexin V/PI. The data for T/B cell frequency are represented as % of these cells in the PBMC population, whereas percentage of apoptotic cells is out of total T or B cells. Serum anti-nucleosomal antibodies and IL 10 were assayed using ELISA. A repeat assessment of these parameters was carried out in 11 active patients when they became inactive. We found higher T-lymphocyte apoptosis in patients with SLE versus controls (14.8 +/- 9.2, 7.2 +/- 3.0; P < 0.05) and a lower frequency of T cells (72.7 +/- 12.6, 79.9 +/- 5.8; P < 0.05). T-lymphocyte apoptosis was higher in patients with active disease compared with inactive (18.5 +/- 11.3, 11.6 +/- 5.4; P = 0.05). Further, T-lymphocyte apoptosis directly correlated with SLEDAI (r = 0.37, P < 0.05) and inversely with T-cell frequency (r = -0.29, P < 0.05). Anti-nucleosomal antibodies correlated with SLEDAI but not apoptosis. On longitudinal follow-up, a decline in T-cell apoptosis was seen in patients with SLE, however this was not statistically significant. We confirmed a higher degree of apoptosis in T-lymphocytes in patients with SLE and found a direct correlation of T-cell apoptosis with disease activity. Patients had reduced T-cell frequency, which inversely correlated with T-cell apoptosis and may suggest a cause-effect relationship.

Upregulated BclG(L) expression enhances apoptosis of peripheral blood CD4+ T lymphocytes in patients with systemic lupus erythematosus

Increased lymphocyte apoptosis has been suggested to contribute to the development of systemic lupus erythematosus (SLE), but the critical factors involved in the apoptotic pathways are still unknown. By long serial analysis of gene expression (LongSAGE) profiles and microarray analyses, a novel apoptosis-related gene BclG(L) expression was found significantly increased in peripheral blood CD4+ T cells of SLE patients, which was correlated with the enhanced CD4+ T cells apoptosis, anti-nuclear antibody (ANA) titer and proteinuria. In vitro, BclG(L) expression could be specially upregulated by SLE serum stimulation and positively correlated with induced CD4+ T cell apoptosis. Enforcing BclG(L) overexpression by lentivirus could directly enhance CD4+ T cell apoptosis, but these apoptosis-inducing effects could be partially inhibited by knockdown of BclG(L) expression. Collectively, these results indicate that increased BclG(L) expression may contribute to the aberrant CD4+ T cell apoptosis which causes an inappropriate immune response and impaired homeostasis in SLE.

Incomplete Killing And Enhanced Activation of Islet-Reactive CD8+ T Cells by FasL-Expressing Dendritic Cells Limits Protection from Diabetes

AIMS

Autologous dendritic cells (DC) are a promising tool for induction of cytotoxic CD8+ T cell immunity against tumors and chronic viral infections. When armed with the death-inducing Fas-ligand (FasL, CD195), DC attenuate delayed-type hypersensitivity reactions and allotransplant rejection by promoting activation-induced cell death in T cells. We investigated the possibility of using FasL-expressing DC to induce deletion of islet-reactive CD8+ T cells in vivo, and to prevent destruction of pancreatic islets in a model of autoimmune diabetes.

METHODS

DC, propagated from mouse bone marrow cells, were purified and made to express FasL and islet-antigen via plasmid transfection. CD8+ T cells (OT-I cells) recognizing the antigen, ovalbumin, were adoptively transferred to transgenic mice expressing ovalbumin in islets (RIP-OVA(lo) mice), and these mice were primed with ovalbumin. To test the potential of DC to prevent diabetes in this model, the mice were later intravenously vaccinated with the transfected DC.

RESULTS

Transfected DC induced partial deletion of antigen-reactive CD8+ T cells in vivo and reduced the level of lymphocyte infiltration into pancreatic islets. Diabetes developed less frequently in vaccinated mice, but this effect was limited. Further in vitro analysis showed that FasL-expressing DC not only deleted many of the responding CD8+ T cells but also promoted the expansion of surviving cells and their IFN-gamma production.

CONCLUSIONS

FasL-expressing DC can also have stimulatory effects on CD8+ T cells warranting further investigation into the optimal design of tolerance-promoting DC-vaccination to prevent autoimmune diabetes.

Features associated with, and the impact of, hemolytic anemia in patients with systemic lupus erythematosus: LX, results from a multiethnic cohort

OBJECTIVE

To examine the clinical and genetic correlates of hemolytic anemia and its impact on damage accrual and mortality in systemic lupus erythematosus (SLE) patients.

METHODS

SLE patients (American College of Rheumatology [ACR] criteria) of Hispanic (Texan or Puerto Rican), African American, and Caucasian ethnicity from the LUMINA (LUpus in MInorities, NAture versus nurture) cohort were studied. Hemolytic anemia was defined as anemia with reticulocytosis (ACR criterion). The association between degrees of hemolytic anemia and socioeconomic/demographic, clinical, pharmacologic, immunologic, psychological, and behavioral variables was examined by univariable and multivariable (proportional odds model) analyses. Genetic variables (FCGR and Fas/Fas ligand polymorphisms) were examined by 2 degrees of freedom test of association and Cochran-Armitage trend tests. The impact of hemolytic anemia on damage accrual and mortality was examined by multivariable linear and Cox regression analyses, respectively.

RESULTS

Of 628 patients studied, 90% were women, 19% were Texan Hispanic, 16% were Puerto Rican Hispanic, 37% were African American, and 28% were Caucasian. Sixty-five (10%) patients developed hemolytic anemia at some time during the disease course, 83% at or before diagnosis. Variables independently associated with degrees of hemolytic anemia were African American ethnicity, thrombocytopenia, and the use of azathioprine. Hemolytic anemia was associated with damage accrual after adjusting for variables known to affect this outcome; however, hemolytic anemia was not associated with mortality.

CONCLUSION

The association of hemolytic anemia with thrombocytopenia suggests a common mechanism in their pathophysiology. Hemolytic anemia is an early disease manifestation and is associated with African American ethnicity and the use of azathioprine; it appears to exert an impact on damage but not on mortality.

Systemic lupus erythematosus: new molecular targets

T cells from patients with systemic lupus erythematosus exhibit a notable array of defects that probably contribute to the origin and development of the disease. Such abnormalities include an abnormal response to stimulation, aberrant expression of molecules that play key roles in intracellular signalling pathways, altered transcription factor activation and binding, and skewed gene expression. The combination of these alterations leads the cell to the expression of a particular phenotype that intense research has gradually uncovered over the last years. The aim of this article is to review the findings that have allowed us to better understand the behaviour of the lupus T cell and highlight the molecules that represent potential therapeutic targets.

Targeting Notch signaling in autoimmune and lymphoproliferative disease

Patients with autoimmune lymphoproliferative syndrome (ALPS) and systemic lupus erythematosis (SLE) have T-cell dysregulation and produce abnormal, activated T lymphocytes and an atypical peripheral T-cell population, termed double negative T cells (DNTs). T-cell functions, including DNT transition in T-cell development and T-cell activation, are critically dependent on Notch signaling. We hypothesized that inhibiting Notch signaling would be effective in ALPS and SLE by reducing the production of abnormal DNTs and by blocking aberrant T-cell activation. We tested this hypothesis using murine models of ALPS and SLE. Mice were randomized to treatment with the notch pathway inhibitor (gamma-secretase inhibitor), N-S-phenyl-glycine-t-butyl ester (DAPT), or vehicle control. Response to treatment was assessed by measurement of DNTs in blood and lymphoid tissue, by monitoring lymph node and spleen size with ultrasound, by quantifying cytokines by bead-array, by ELISA for total IgG and anti-double-stranded DNA (dsDNA) specific antibodies, and by histopathologic assessment for nephritis. We found a profound and statistically significant decrease in all disease parameters, comparing DAPT-treated mice to controls. Using a novel dosing schema, we avoided the reported toxicities of gamma-secretase inhibitors. Inhibiting the Notch signaling pathway may thus present an effective, novel, and well-tolerated treatment for autoimmune and lymphoproliferative diseases.

The role of Ras signaling in lupus T lymphocytes: biology and pathogenesis

Ras is a GTP-binding protein that plays multiple important roles in cell activation, including proliferative and inflammatory responses. Ras regulation is complex and depends upon post-translational processing, organelle-specific localization and the activation/deactivation of Ras by a number of regulatory molecules. Ras activation in T lymphocytes demonstrates unique features, including its dependence on the T cell receptor and the ability of Ras to signal from both the plasma membrane and the Golgi. Abnormalities of Ras expression, activation and signaling pathways in T lymphocytes appear to play important roles in the development of autoimmunity in general, and systemic lupus erythematosus in particular. In this manuscript, we review the basic biology of Ras in T lymphocytes, and the ways in which T lymphocyte Ras abnormalities may contribute to the development of a lupus phenotype.

Decoy receptor 3 ameliorates an autoimmune crescentic glomerulonephritis model in mice

Autoimmune crescentic glomerulonephritis (ACGN) is a variant of crescentic glomerulonephritis. The outcome of treatment of crescentic glomerulonephritis is poor. Binding of decoy receptor 3 (DCR3) to its ligand is capable of downregulating the alloresponsiveness of T cells. DCR3 has also been shown to benefit an experimental autoimmune model of diabetes. This study tested the hypothesis that a potential immune regulator, DCR3, could prevent the evolution of ACGN. With the use of an established ACGN model in mice, mice were treated with 100 microg/10 g body wt human DCR3 by hydrodynamics-based gene delivery at 14-d intervals. The results showed that the gene therapy resulted in (1) suppression of T and B cell activation and T cell proliferation; (2) a reduction in serum levels of proinflammatory cytokines; (3) improvement of proteinuria and renal dysfunction; (4) prevention of glomerular crescent formation, renal interstitial inflammation, and glomerulosclerosis; (5) a reduction in serum levels of autoantibodies and glomerular immune deposits; (6) inhibition of apoptosis in the spleen and kidney; (7) prevention of T cell and macrophage infiltration of the kidney; and (8) suppression of fibrosis-related gene expression in the kidney compared with empty vector-treated (disease control) ACGN mice. On the basis of these findings, it is proposed that human DCR3 exerts its preventive and protective effects on ACGN through modulation of T cell activation/proliferation, B cell activation, protection against apoptosis, and suppression of mononuclear leukocyte infiltration in the kidney.