Deficient phytohemagglutinin-induced interleukin-2 activity in patients with inactive systemic lupus erythematosus is correctable by the addition of phorbol myristate acetate

Casitas B lineage lymphoma b is a key regulator of peripheral tolerance in systemic lupus erythematosus

OBJECTIVE

To analyze whether the expression and modulation of T cell receptor (TCR) signaling is dependent on Casitas B lineage lymphoma b (Cbl-b) in T cells from patients with systemic lupus erythematosus (SLE) upon stimulation with a tolerogenic substance.

METHODS

Peripheral blood mononuclear cells were obtained from 20 patients with SLE (active disease or in remission) and 20 healthy controls. Levels of Cbl-b expression were measured using reverse transcription-polymerase chain reaction and Western blotting in peripheral CD4+ T cells from SLE patients and healthy controls upon anergy induction. Cell proliferation was measured using the carboxyfluorescein diacetate succinimidyl ester dilution method. Cytokine production was analyzed by luminometry, and surface expression of activation markers was assessed by flow cytometry. Transfection assays were performed to induce overexpression of Cbl-b, and phosphorylation of TCR-associated kinases was evaluated.

RESULTS

CD4+ T cells from SLE patients displayed resistance to anergy (as evidenced by increased cell proliferation, interleukin-2 production, and expression of activation and costimulatory markers), and this was associated with altered Cbl-b expression. Upon ionomycin treatment, primary T cells showed enhanced MAPK activity and decreased Akt phosphorylation, which was representative of the anergic state. In T cells from lupus patients, Cbl-b overexpression led to increased expression of phosphorylated MAPK, thus indicating the reversibility of anergy resistance.

CONCLUSION

These findings suggest that abnormal peripheral tolerance in SLE is caused by a deficiency in Cbl-b, and that this ubiquitin ligase plays a key role in regulating TCR signaling during the induction of peripheral tolerance.

Transcriptional regulation of interleukin 2 in SLE T cells

Interleukin-2 (IL-2) is a central cytokine required for the activation of T, B, and NK cells. It propagates the immune response and terminates it by promoting the activation induced cell death of T cells. IL-2 production is altered in T cells of patients with systemic lupus erythematosus (SLE). The consequence of reduced IL-2 production in SLE is decreased immune response to infectious agents. Decreased IL-2 production by SLE T cells is the result of transcriptional repression of the IL-2 gene. This article will review the defective transcription regulation of IL-2 in SLE T cells, which is the result of decreased expression of the enhancers NF-kappa B and AP1 and the increased expression of the transcriptional repressor CREM.

Pathogenesis of systemic lupus erythematosus

The exact patho-aetiology of systemic lupus erythematosus (SLE) remains elusive. An extremely complicated and multifactorial interaction among various genetic and environmental factors is probably involved. Multiple genes contribute to disease susceptibility. The interaction of sex, hormonal milieu, and the hypothalamo-pituitary-adrenal axis modifies this susceptibility and the clinical expression of the disease. Defective immune regulatory mechanisms, such as the clearance of apoptotic cells and immune complexes, are important contributors to the development of SLE. The loss of immune tolerance, increased antigenic load, excess T cell help, defective B cell suppression, and the shifting of T helper 1 (Th1) to Th2 immune responses leads to B cell hyperactivity and the production of pathogenic autoantibodies. Finally, certain environmental factors are probably required to trigger the disease.

The expression and significance of intracellular T helper cytokines in systemic lupus erythematosus

To analyze the Th1 and Th2 paradigm of peripheral T helper cells in patients with systemic lupus erythematosus (SLE). The intracellular Th1 and Th2 cytokines were analyzed in fresh blood T cells from 20 SLE patients who had not yet received any treatment. Th1 and Th2 cells were quantitated based on their intracellular cytokine content as assessed by flow cytometry. Cytokine expressions were correlated with clinical features, laboratory findings, and disease activities. There was no difference in the expression of intracellular IFN-y, or IL-4 between SLE patients and healthy controls. However, the IL-2 and IL-10 levels were significantly higher and lower respectively in the lupus patients than in the control group. In addition, patients with arthritis had higher IFN-gamma expression than patients without arthritis. Moreover, patients with serositis or CNS involvement had higher IL-4 expression than in patients without these manifestations. There was no correlation between the SLEDAI scores and the cytokine expression levels. However, patients with serum anti-ds DNA antibodies had higher IL-10 levels than in those without these antibodies. The present study demonstrates that a Th1 pattern of intracellular cytokines predominates in patients with SLE prior to treatment. The pattern of particular intracellular T cell cytokines may suggest specific clinical manifestations and disease progression of SLE.

Neuroendocrine and immune aspects of fibromyalgia

Fibromyalgia is a form of non-articular rheumatism characterised by long term (>3 months) and widespread musculoskeletal aching, stiffness and pressure hyperalgesia at characteristic soft tissue sites, called soft tissue tender points. The biophysiology of fibromyalgia, however, has remained elusive and the treatment remains mainly empirical. This article reviews the neuroendocrine-immune pathophysiology of fibromyalgia. There is no major evidence that fibromyalgia is accompanied by activation of the inflammatory response system, by immune activation or by an inflammatory process. There is some evidence that fibromyalgia is accompanied by some signs of immunosuppression, suggesting that immunomodifying drugs could have potential in the treatment of fibromyalgia. Recent trials with cytokines, such as interferon-alpha, have been undertaken in patients with fibromyalgia. Immunotherapy with these agents, however, may induce symptoms reminiscent of fibromyalgia and depression in a considerable number of patients. Lowered serum activity of prolyl endopeptidase (PEP), a cytosolic endopeptidase that cleaves peptide bonds on the carboxyl side of proline in proteins of relatively small molecular mass, may play a role in the biophysiology of fibromyalgia through diminished inactivation of algesic and depression-related peptides, e.g. substance P. Trials with PEP agonists could be worthwhile in fibromyalgia. The muscle energy depletion hypothesis of fibromyalgia is supported by findings that this condition is accompanied by lowered plasma levels of branched chain amino acids (BCAAs), i.e. valine, leucine and isoleucine. Since there is evidence that BCAA supplementation decreases muscle catabolism and has ergogenic values, a supplemental trial with BCAAs in fibromyalgia appears to be justified.

Interleukin-2 and systemic lupus erythematosus--fifteen years later

Systemic lupus erythematosus (SLE) is a highly heterogeneous disorder in which multiple immunologic abnormalities have been described. In this review, we thoroughly analyse the impaired T cell production of, and response to, interleukin-2 (IL-2) characteristic of patients with SLE. Since it was first reported, several articles have provided us with enlightening, but somewhat confusing, data that reveal the complexity of the subject. The IL-2 production by T cells is part of a complex network in which a discrete alteration is capable of disrupting the whole system. On the other hand, regulatory mechanisms exist that, in an attempt to compensate the primary alteration, provoke secondary defects. Evidence indicates that this defect is not intrinsic, but rather, results from multiple microenvironmental influences that act on the T cell and modify its activation state and its cytokine production. Abnormalities in co-stimulatory mechanisms and in cytokines that may be related to the IL-2 production deficiency, have been described in patients with SLE. We also consider the information derived from murine SLE models, IL-2 knockout models and reports concerning the immune dysregulation present in patients with SLE.

Dysregulation of T helper cell cytokines in autoimmune prone NZB x NZW F1 mice

Multifactorial involvement in the pathogenesis of autoimmune NZB/W F1 mice has been well documented. To further elucidate the role of cytokines in the disease development of murine lupus, single spleen cells isolated from NZB/W F1 and non-autoimmune C57BL/6 mice were stimulated with T cell mitogens or anti-CD3 antibody at pre-determined optimal concentration. Supernatants were collected and assayed for production of cytokines including IL-2, gamma-IFN, IL-3, IL-4, IL-5 and IL-10. In both young and old mice, cytokine profiles by mitogen-stimulated T cells showed higher TH2 (type 2 T helper) cell-related cytokine production in NZB/W F1 mice compared to those in non-autoimmune C57BL/6 mice. In contrast, cytokines produced by TH1 (type 1 T helper) cells, such as gamma-IFN and IL-2, were lower in NZB/W F1 mice by stimulation with either mitogen or anti-CD3 antibody. In addition, cytokine production at different time points also demonstrated decreased gamma-IFN and increased IL-4 levels by anti-CD3 stimulated splenic cells in autoimmune NZB/W F1 mice. Furthermore, the IL-10 levels produced by lipopolysaccharide (LPS)-stimulated splenic and peritoneal exudate cells were higher in young NZB/W F1 mice compared to those in C57BL/6 mice. Our data suggest that dysregulation between TH1 and TH2 cells may play an important role in the pathogenesis of autoimmunity in NZB/W F1 mice.

Low serum levels of dehydroepiandrosterone may cause deficient IL-2 production by lymphocytes in patients with systemic lupus erythematosus (SLE)

The principal cause of IL-2 deficiency, a common feature of both murine lupus and human SLE, remains obscure. Recent studies of our own as well as others have shown that dehydroepiandrosterone (DHEA), an intermediate compound in testosterone synthesis, significantly up-regulates IL-2 production of T cells, and that administration of exogenous DHEA or IL-2 via a vaccinia construct to murine lupus dramatically reverses their clinical autoimmune diseases. Thus, we have examined serum levels of DHEA in patients with SLE to test whether abnormal DHEA activity is associated with IL-2 deficiency of the patients. We found that nearly all of the patients examined have very low levels of serum DHEA. The decreased DHEA levels were not simply a reflection of a long term corticosteroid treatment which may cause adrenal atrophy, since serum samples drawn at the onset of disease, which are devoid of corticosteroid treatment, also contained low levels of DHEA. In addition, exogenous DHEA restored impaired IL-2 production of T cells from patients with SLE in vitro. These results indicate that defects of IL-2 synthesis of patients with SLE are at least in part due to the low DHEA activity in the serum.

Cytokines in rheumatic diseases

IL-1 and related cytokines have multiple biologic activities relevant to the rheumatic diseases. In addition to mediating inflammatory and immune responses, these proteins regulate many aspects of connective tissue metabolism. The cytokines interact in complex cascades: because of this, and various technical reasons, the exact role of cytokines in the pathogenesis of rheumatic diseases remains uncertain. However, considerable experimental data suggest that the abnormal regulation of cytokines contributes to such siseases as inflammatory arthritis, systemic lupus erythematosus, scleroderma, and dermatomyositis. Animal models of these diseases have contributed to understanding the role of cytokines in pathogenesis. Furthermore, drugs useful in treating these diseases affect cytokine pathways; some cytokines, their antagonists, or related substances have been used therapeutically to treat rheumatic diseases. The therapeutic use of these agents will likely increase as knowledge about the role of cytokines in the pathogenesis of rheumatic diseases expands.

B7/BB1 provides an important costimulatory signal for CD3-mediated T lymphocyte proliferation in patients with systemic lupus erythematosus (SLE)

Successful T cell activation via the T cell receptor (TCR)/CD3 complex requires at least one contact-dependent second signal delivered by costimulatory molecules, including the B7/BB1 molecule, that are present on antigen-presenting cells (APC). SLE is characterized by multiple complex lymphocyte abnormalities of undefined molecular origin. It is currently unclear whether an intrinsic defect of T cell or an underlying APC dysfunction is responsible for defective in vitro proliferation of T cells from patients with SLE. We planned the present experiments to ask whether the TCR/CD3-mediated and B7/BB1-costimulated T cell proliferation is normal in these patients. We used enriched T cell populations that were stimulated with an anti-CD3 MoAb in the presence of controlled quantities of functional B7/BB1 antigen. Freshly isolated T cells from 17 SLE patients (10 and seven patients with either active or inactive disease, respectively) and 11 normal individuals were cocultured with irradiated B7/BB1-transfected P815 cells or parental P815 cells in the presence of OKT3 MoAb at optimal and suboptimal concentrations for 2.5-7 days. Normal or SLE T cells responded similarly to stimulation via anti-CD3, in the absence of B7/BB1 antigen. A several-fold increase in T cell proliferation in the presence of B7/BB1 antigen was observed. Proliferation was inhibited in the presence of anti-B7/BB1 MoAb, but not with control MoAbs. Interestingly, dose-response curves and time kinetics of B7/BB1 costimulation were similar in T cells from patients with either active or inactive SLE at the time of study, and normal individuals. In addition, no differences in the IL-2 receptor release by T cells cultured under these conditions were observed between SLE patients and normal individuals. These results demonstrate that CD28 signalling is not intrinsically impaired in patients with SLE; further studies to investigate whether abnormal B7/BB1 expression is involved in the autoimmune process are needed.

Rapamycin prolongs survival and arrests pathophysiologic changes in murine systemic lupus erythematosus

OBJECTIVE

To evaluate the effects of oral rapamycin (RAPA), a macrolide immunosuppressant that has been shown to interfere with T cell activation events, on the course of spontaneous disease progression in the MRL/MpJ/lpr/lpr (MRL/l) mouse model of lupus.

METHODS

RAPA treatment (6, 12, or 25 mg/kg 3 times per week) was evaluated by monitoring survival rates, autoantibody levels, and urinary albumin levels. Additionally, concanavalin A responsiveness, interleukin-2 (IL-2) production, lymphoid organ size, and histopathology were evaluated ex vivo.

RESULTS

RAPA prevented the typical rise in anti-double-stranded DNA antibody and urinary albumin levels and prolonged survival. Spleen and lymph node sizes were significantly decreased, inflammatory changes in the lung, liver, kidney, spleen, lymph node, and thymus were significantly reduced, and T cell mitogen-stimulated splenocyte proliferation and IL-2 production were restored.

CONCLUSION

Data from 3 independent experiments demonstrated that RAPA significantly reduced or prevented many pathologic features of lupus normally seen in the MRL/l mouse, and suggest that RAPA may be useful as a therapeutic agent in SLE in humans.

Lithium in vitro enhances interleukin-2 production by T cells from patients with systemic lupus erythematosus

Cellular immunity is impaired in patients with systemic lupus erythematosus (SLE). A decreased production of interleukin-2 by T cells isolated from blood of patients with SLE was found. The decrease correlated with severity of the disease. It was shown that incubation in vitro of T cells with 5 mM of lithium chloride augmented interleukin-2 production. The increase in cultures of T cells from patients with SLE was higher that than in healthy individuals. It is believed that lithium increases the cytosol inositol triphosphate level and subsequently augmented impaired intracellular signal transduction in the T cells from patients with SLE.

The putative role of cytokines in the induction of primary anti-phospholipid syndrome in mice

Antiphospholipid syndrome (APLS) is characterized by thrombocytopenia, thromboembolic phenomena and recurrent fetal loss, associated with anti-cardiolipin antibodies (ACA) and/or lupus anticoagulant. The syndrome may be primary or may be associated with other conditions such as systemic lupus erythematosus (SLE). In this study we induced primary APLS following immunization of BALB/c mice with a human monoclonal ACA (H-3). Analysis of the cytokine profile of the mice with experimental APLS indicated low production of IL-2, IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) by concanavalin A (Con A)-stimulated splenocytes of H-3 immunized mice. It seems that the low levels of IL-3 and GM-CSF have a potential role in the fetal loss of the APLS. Whatever the mechanism of IL-3 and GM-CSF in preventing fetal loss, these results may have therapeutic bearing on the reproductive outcome in women and other species with APLS.

A defect in the protein kinase C system in T cells from patients with systemic lupus erythematosus

To determine whether there is an intrinsic defect in T cells from patients with systemic lupus erythematosus (SLE), we studied signal transduction systems, assaying the total protein kinase C (PKC) levels and the phorbol myristate acetate (PMA)-induced activation of PKC in PHA-treated T cells. T cells from SLE patients showed a decrease in proliferation in response to PMA, but not to PHA, thereby suggesting the existence of an intrinsic abnormality in the PKC-mediated activation pathway. Total PKC activity in the T cells from SLE patients was significantly decreased. Although stimulation with PMA induced a translocation of PKC from the cytosol to the particulate fraction, translocated PKC activity after 2 nM PMA treatment was decreased in the SLE T cells. Furthermore, PMA-induced phosphorylation of 80-kDa substrates was also decreased in SLE T cells. These results suggest that there is a reduced PKC activity and an impaired PKC activation in response to PMA in the SLE T cells, a finding which may explain, if partially, the defect in T cell activation in patients with SLE.

Altered interleukin-2 secretion in patients with primary fibromyalgia syndrome

Interleukin-2 (IL-2) production was studied in T lymphocytes and isolated CD4+ T lymphocytes from 12 patients with primary fibromyalgia syndrome and 10 healthy volunteers. The dose and time kinetics of IL-2 production by concanavalin A-stimulated T cells and CD4+ T cells of fibromyalgia patients differed from findings in controls by 1) a need for a higher concentration of mitogen in order to achieve optimal IL-2 secretion, and 2) a delay in the peak time of optimal IL-2 secretion. Unlike normal IL-2 secretion, which was higher after removal of CD8+ T cells, the pattern and degree of IL-2 secretion by cells from fibromyalgia patients were not changed following removal of CD8+ T cells. Addition of calcium ionophore in assays using suboptimal concanavalin A concentrations did not correct the reduction in IL-2 secretion by fibromyalgia patient T cells, but addition of phorbol myristate acetate induced normal secretion of IL-2. These findings suggest that there is a defect in the IL-2 pathway, which is related to protein kinase C activation and does not involve impairment of Ca2+ elevation, in patients with fibromyalgia.

Defective CD2 pathway T cell activation in systemic lupus erythematosus

CD2 (T11; sheep erythrocyte receptor) is the surface component of an alternative, antigen-independent pathway of human T cell activation. The response to certain anti-CD2 antibodies is relatively independent of accessory cell signals and therefore provides a direct measurement of T cell function. The CD2 pathway may be important in the differentiation of thymocytes, on which the expression of CD2 precedes the appearance of the CD3-T cell receptor complex. In view of the impaired T cell regulation of immune responses in patients with systemic lupus erythematosus (SLE), we examined the activation of peripheral blood lymphocytes by anti-CD2 antibodies in 57 SLE patients and 32 normal control subjects. The CD2 pathway response was lower in the SLE patients (P less than 0.0001); 18 of the 57 SLE patients had a lower response than any of the control subjects. The SLE low-responder patients did not differ from the normal-responder patients in terms of disease activity or use of antiinflammatory and immunosuppressive medications. Low responses to anti-CD2 were corrected to normal by the coaddition of a submitogenic amount of phorbol myristate acetate (1 ng/ml). In some low-responder patients, the responses were normalized by the removal of non-T cells. The data indicate that some SLE patients have impaired responses to CD2 pathway activation and that this may reflect intrinsic T cell defects and/or regulatory influences of non-T cells.

Impaired T-cell activation in patients with systemic lupus erythematosus

Interleukin-2 (IL-2) production was studied in T lymphocytes from 32 patients with systemic lupus erythematosus (SLE) and 27 healthy volunteers. The IL-2 production by phytohemagglutinin (PHA)-stimulated cells from SLE patients was significantly depressed compared to control values, with a correlation between degree of depression and disease activity. The depressed IL-2 production by SLE T cells are largely reversed by the addition of either phorbol ester (PMA) or partially by a calcium ionophore. SLE T cells had significantly lower peak increases in intracellular free calcium [( Ca2+]i) than controls after stimulation by PHA or by a monoclonal antibody against the CD3 antigen. This abnormality was found even in T cells from patients with mild disease activity or in those whose T cells produced normal amounts of IL-2. Calcium ionophore produced similar increases in [Ca2+]i in SLE patients as in normals. These results suggest that a major component of the defect responsible for decreased IL-2 production by SLE lymphocytes is proximal to protein kinase C activation and may involve impaired signal transduction after activation of the antigen receptor complex.

Familial occurrence of impaired interleukin-2 activity and increased peripheral blood B cells actively secreting immunoglobulins in systemic lupus erythematosus

PURPOSE

We tested the hypothesis that some abnormalities of immune functions are genetically controlled in patients with systemic lupus erythematosus (SLE).

SUBJECTS AND METHODS

We used a phytohemagglutinin-induced interleukin-2 (IL-2) activity assay and a spontaneous plaque-forming cell assay to evaluate T-cell and B-cell function, respectively, in 34 clinically healthy family members of six SLE probands.

RESULTS

Impaired IL-2 activity was found in 15 of the 29 consanguineous relatives. There was no relation between the household relatives and the nonhousehold relatives; none of the five nonconsanguineous household persons had abnormal results. Results for the B-cell assay were abnormal in 22 of the 29 consanguineous relatives. The B-cell abnormalities were more commonly observed in the consanguineous household relatives; four of the five nonconsanguineous household relatives also had abnormal assay results.

CONCLUSION

The findings indicate that the impaired IL-2 activity in relatives appears to strongly correlate with a genetic relationship. Although the evidence favors a genetic basis for the B-cell abnormalities, environmental effects may also contribute to the familial occurrence of these abnormalities.

Induction of excessive B cell proliferation and differentiation by an in vitro stimulus in culture in human systemic lupus erythematosus

B cell hyperactivity present in the body in patients with systemic lupus erythematosus (SLE) can be detectable via almost any measure of B cell function. Nonetheless, the basis for the B cell hyperactivity is difficult to study in vitro. In this study, we have obtained the resting B cells from patients with entirely inactive SLE by collecting them sedimenting in a high density fraction on a Percoll density gradient. These resting SLE B cells proliferated in vitro at a higher rate than normal B cells when exposed to Staphylococcus aureus Cowan I (SAC). In addition, significant proliferation was observed earlier in the course of culture in SLE patients than in normal controls. Moreover, the SLE resting B cells, once triggered by SAC produced abnormally high numbers of immunoglobulin-secreting cells in response to T cell-derived soluble factors. There was less frequency of circulating Leu 1+ B cells in the SLE patients than in normal controls. Moreover, not only Leu 1+ B cells but also Leu 1- B cells of SLE patients were more responsive to SAC than those of normal controls. The results indicate that the B cell hyperactivity in human SLE can be induced by in vitro stimuli, and may not be limited to the Leu 1+ B cell subset.