Treatment with a tissue-selective oestrogen complex does not affect disease pathology but reduces pre-BI cells in lupus-prone mice

OBJECTIVE

Systemic lupus erythematosus (SLE or lupus) is an autoimmune disease characterized by B-cell dysfunction, production of autoantibodies, and immune complex formation. Lupus is overrepresented in females, indicating that sex hormones play a role in the pathophysiology. Treatment with a tissue-selective oestrogen complex (TSEC) containing conjugated oestrogens and the selective oestrogen receptor modulator bazedoxifene (BZA) protects against postmenopausal vasomotor symptoms and osteoporosis, but its impact on organ damage in lupus is not fully understood.

METHOD

We used ovariectomized MRL/lpr mice, treated with two different physiological doses of 17β-oestradiol-3-benzoate (E2), BZA, or TSEC (E2 plus BZA), to assess early and late B-cell development and to determine histological disease manifestations in the kidneys and salivary glands.

RESULTS

TSEC treatment reduced the frequency of the pre-BI population in bone marrow to levels equivalent to treatment with physiological doses of E2 alone but did not affect any of the other examined B-cell populations. Our earlier studies indicated that TSEC treatment did not aggravate disease development in ovariectomized MRL/lpr mice, while protecting against trabecular bone loss. Here, we follow up on our previous study and show that neither ovariectomy alone nor TSEC treatment of ovariectomized MRL/lpr mice influenced perivascular lymphocyte infiltration to the kidneys or salivary glands.

CONCLUSION

TSEC does not aggravate a mouse model of lupus, when given in doses that protect against postmenopausal lupus-associated bone loss. This indicates that further investigations into TSEC as a treatment for osteoporosis or vasomotor symptoms in postmenopausal women with SLE are warranted.

AB0022 SELECTIVE ESTROGEN RECEPTOR MODULATORS AND TISSUE-SELECTIVE ESTROGEN COMPLEX DO NOT SHARE ESTROGENIC EFFECTS ON IGG SIALYLATION IN AUTOIMMUNE CONDITIONS

Background

Women entering menopause, with a decrease in estrogen levels, display an increased incidence of rheumatoid arthritis (RA). Estrogen (E2) treatment has beneficial effects on IgG pathogenicity by altering the sialylation grade which affect the binding ability to FcR1. E2 replacement may therefore be beneficial in pre-RA patients having autoantibodies. Exposure to estrogen is associated with negative side effects, therefore selective estrogen receptor modulators (SERMs) have been developed with estrogenic protective effect on bone but minimal impact on the reproductive system2. The SERM, Bazeodoxifene (BZA), as well as tissue-selective estrogen complex (TSEC), a combination of conjugated estrogen and BZA, have been approved for treatment of postmenopausal bone loss3-5

Objectives

The purpose of this study was to investigate the impact of BZA and TSEC on IgG sialylation grade which affects the pathogenicity as well as to determine the effects on total serum protein sialylation.

Methods

C57Bl6 mice were subjected to ovariectomy to stop the endogenous E2 production and mimicked the postmenopausal status. Mice were then treated with E2, BZA, TSEC, or vehicle, followed by ovalbumin (OVA) immunization to induce the IgG levels. Blood was collected before treatment started and at termination. In serum total IgG, OVA specific IgG and the degree of IgG-sialylation were quantified with ELISA. Sialyation of total serum proteins was determined with sialic acid assay quantification kit. Expression of sialyltransferase protein was analyzed in the bone marrow (BM) and spleen cell compartment using flow cytometry. The mRNA expression of glycosyltransferase was analyzed by qPCR analysis.

Results

Neither BZA nor TSEC significantly altered the total IgG levels or sialylation grade of IgG. Indeed, E2 significantly altered IgG sialylation. We showed that BZA increased sialyltransferase protein in plasma cells in a similar manner as E2. Further, neither E2, BZA or TSEC had any significant impact on sialic acids in whole serum protein and not in the mRNA expression of glycosyltransferase in the liver, BM, or gonadal fat.

Conclusion

In this study, we were not able to detect any alteration by TSEC or BZA treatment on IgG-sialylation grade and thereby pathogenicity of the IgG. Neither E2 nor BAZ or TSEC show any significant alteration on general sialylation, but our results suggest that further studies are required to understand E2, SERM, and TSEC full effect on protein sialylation in autoimmune conditions.

Keywords: IgG sialylation, protein glycosylation, SERMs

References

[1]Engdahl C, Bondt A, Harre U, et al. Estrogen induces St6gal1 expression and increases IgG sialylation in mice and patients with rheumatoid arthritis: a potential explanation for the increased risk of rheumatoid arthritis in postmenopausal women. Arthritis Research & Therapy. 2018/05/02 2018;20(1):84. doi:10.1186/s13075-018-1586-z

[2]Pinkerton JV, Thomas S. Use of SERMs for treatment in postmenopausal women. J Steroid Biochem Mol Biol. Jul 2014;142:142-54. doi:10.1016/j.jsbmb.2013.12.011

[3]Miller PD, Chines AA, Christiansen C, et al. Effects of bazedoxifene on BMD and bone turnover in postmenopausal women: 2-yr results of a randomized, double-blind, placebo-, and active-controlled study. J Bone Miner Res. Apr 2008;23(4):525-35. doi:10.1359/jbmr.071206

[4]Pinkerton JV, Pickar JH, Racketa J, Mirkin S. Bazedoxifene/conjugated estrogens for menopausal symptom treatment and osteoporosis prevention. Climacteric. Oct 2012;15(5):411-8. doi:10.3109/13697137.2012.696289

[5]Silverman SL, Christiansen C, Genant HK, et al. Efficacy of bazedoxifene in reducing new vertebral fracture risk in postmenopausal women with osteoporosis: results from a 3-year, randomized, placebo-, and active-controlled clinical trial. J Bone Miner Res. Dec 2008;23(12):1923-34. doi:10.1359/jbmr.080710

Disclosure of Interests

None declared

Factors associated with changes in volumetric bone mineral density and cortical area in men with ankylosing spondylitis: a 5-year prospective study using HRpQCT

Patients with ankylosing spondylitis (AS) have impaired volumetric bone mineral density (vBMD) assessed with high-resolution peripheral computed tomography (HRpQCT). This first longitudinal HRpQCT study in AS shows that cortical and trabecular vBMD decreased at tibia and that signs of inflammation were associated with cortical bone loss at tibia and radius.

INTRODUCTION

Patients with ankylosing spondylitis (AS) have reduced volumetric bone mineral density (vBMD) in the peripheral skeleton assessed with high-resolution peripheral quantitative computed tomography (HRpQCT). The aims were to investigate longitudinal changes in vBMD, cortical area, and microarchitecture and to assess factors associated with changes in vBMD and cortical area in men with AS.

METHODS

HRpQCT of radius and tibia was performed in 54 men with AS at baseline and after 5 years. Univariate and multivariable linear regression analyses were used.

RESULTS

At tibia, there were significant decreases exceeding least significant changes (LSC) in cortical and trabecular vBMD, mean (SD) percent change -1.0 (1.9) and -2.7 (5.0) respectively (p<0.001). In multivariable regression analyses, increase in disease activity measured by ASDAS_CRP from baseline to follow-up was associated with decreases in cortical vBMD (β -0.86, 95% CI -1.31 to -0.41) and cortical area (β -1.66, 95% CI -3.21 to -0.10) at tibia. At radius, no changes exceeded LSC. Nonetheless, increase in ASDAS_CRP was associated with decreases in cortical vBMD, and high time-averaged ESR was associated with decreases in cortical area. Treatment with TNF inhibitor ≥ 4 years during follow-up was associated with increases in cortical vBMD and cortical area at tibia, whereas exposure to bisphosphonates was associated with increases in cortical measurements at radius. No disease-related variables or treatments were associated with changes in trabecular vBMD.

CONCLUSION

The findings in this first longitudinal HRpQCT study in patients with AS strengthen the importance of controlling disease activity to maintain bone density in the peripheral skeleton.

Osteoporosis in a murine model of postmenopausal lupus

BACKGROUND/OBJECTIVE

Postmenopausal women with systemic lupus erythematosus have an increased risk of osteoporosis and associated fractures. Their increased osteoporosis risk is probably caused by a high level of inflammation, use of glucocorticoids, impaired kidney function, and early menopause as these are known risk factors for osteoporosis. Due to these risk factors and the lack of safe and effective treatments, new therapies for the treatment of osteoporosis in this group of patients are needed. Ovariectomized MRL/lpr mice constitute a well-established model for studies of postmenopausal systemic lupus erythematosus; however, it is not clear to what extent this experimental model is associated with the development of osteoporosis. Thus, the aim of this study was to characterize the skeleton of ovariectomized MRL/lpr mice to determine the suitability of this model in studies of prospective new therapies for osteoporosis in postmenopausal systemic lupus erythematosus patients.

METHODS

Skeletal parameters were measured in MRL/lpr mice and MRL/++ control mice, using peripheral quantitative computed tomography, high-resolution micro-computed tomography and biomechanical analyses. mRNA expression of bone-remodeling markers was measured by quantitative polymerase chain reaction and serological markers of lupus disease were evaluated using ELISA.

RESULTS

Total bone mineral density was reduced in MRL/lpr mice compared with MRL/++ mice and MRL/lpr mice had reduced cortical and trabecular bone thickness compared with MRL/++ mice. In line with the low bone mass of MRL/lpr mice, gene expression analysis of cortical bone from these mice indicated an increased osteoclast activity as well as a decreased osteoblastogenesis and osteoblast activity, compared with MRL/++ mice.

CONCLUSION

Ovariectomized MRL/lpr mice constitute a valuable experimental model for studies of osteoporosis development in postmenopausal systemic lupus erythematosus and this model is thus suitable for future studies of osteoporosis treatment in systemic lupus erythematosus.

Hepatocyte growth factor is a potential biomarker for osteoproliferation and osteoporosis in ankylosing spondylitis

We explored relations between serum hepatocyte growth factor (HGF), disease activity, osteoproliferation, and bone mineral density (BMD) in ankylosing spondylitis (AS), in comparison with healthy controls. HGF was increased especially in male AS patients and smokers and associated with both lower BMD and more chronic radiographic changes in the spine.

INTRODUCTION

Ankylosing spondylitis (AS) is characterized by both osteoproliferation and increased bone loss. Biomarkers are requested to predict the processes. The aims of this study were to compare serum levels of hepatocyte growth factor (HGF), matrix metalloproteinase-3 (MMP-3), and vascular endothelial growth factor (VEGF) in AS patients with healthy controls (HC) and to explore the associations with disease activity, osteoproliferation, and bone mineral density (BMD).

METHODS

Serum from AS patients (modified NY-criteria) and HC was analyzed for HGF, MMP-3, and VEGF with ELISA. Disease activity parameters were collected. Osteoproliferation was assessed with modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) and BMD was measured in femoral neck.

RESULTS

Totally, 204 AS patients and 80 sex and age matched HC were included. Serum HGF was higher in the AS patients compared with the HC, whereas serum MMP-3 and VEGF were not. Serum HGF was also higher in smokers and in the male AS patients positively correlated with age, BASMI, and mSASSS, and negatively correlated with BMD. The biomarkers were all positively associated with ESR, CRP, and WBC. In multiple linear regression analysis serum HGF remained associated with higher mSASSS and lower BMD, after adjusting for age, sex, CRP, smoking, and body mass index.

CONCLUSIONS

Serum HGF was increased in male AS patients and associated with higher mSASSS and lower BMD. In addition, serum HGF was positively associated with risk factors for osteoproliferation such as age, CRP and smoking. HGF could be a potential biomarker of importance for the bone metabolism in AS.

TRIAL REGISTRATION

NCT00858819.

ERα expression in T lymphocytes is dispensable for estrogenic effects in bone

Estrogen treatment has positive effects on the skeleton, and we have shown that estrogen receptor alpha (ERα) expression in cells of hematopoietic origin contributes to a normal estrogen treatment response in bone tissue. T lymphocytes are implicated in the estrogenic regulation of bone mass, but it is not known whether T lymphocytes are direct estrogen target cells. Therefore, the aim of this study was to determine the importance of ERα expression in T lymphocytes for the estrogenic regulation of the skeleton using female mice lacking ERα expression specifically in T lymphocytes (Lck-ERα^-/-) and ERα^flox/flox littermate (control) mice. Deletion of ERα expression in T lymphocytes did not affect bone mineral density (BMD) in sham-operated Lck-ERα^-/- compared to control mice, and ovariectomy (ovx) resulted in a similar decrease in BMD in control and Lck-ERα^-/- mice compared to sham-operated mice. Furthermore, estrogen treatment of ovx Lck-ERα^-/- led to an increased BMD that was indistinguishable from the increase seen after estrogen treatment of ovx control mice. Detailed analysis of both the appendicular (femur) and axial (vertebrae) skeleton showed that both trabecular and cortical bone parameters responded to a similar extent regardless of the presence of ERα in T lymphocytes. In conclusion, ERα expression in T lymphocytes is dispensable for normal estrogenic regulation of bone mass in female mice.

Decreased serum levels of TGF-β1 are associated with renal damage in female patients with systemic lupus erythematosus

INTRODUCTION

Transforming growth factor β1 (TGF-β1) has a large role in the control of autoimmunity. TGF-β1 production by lymphocytes is reduced in systemic lupus erythematosus (SLE). Decreased levels of TGF-β1 might associate to disease susceptibility, activity and organ damage in SLE. However, the correlation between TGF-β1 levels and severity of renal damage in SLE has not been examined.

METHODS

The present study was undertaken to assess the serum levels of total and active TGF-β1 in 150 female patients with SLE and 31 healthy women. Simple and multiple regression analyses between TGF-β1 levels and the diseases-related variables were performed in patients with SLE.

RESULTS

Serum levels of both total and active TGF-β1 were significantly reduced in patients with SLE compared with levels in healthy controls (p < 0.01). Total TGF-β1 levels correlated positively with white blood cell, platelet counts, calculated glomerular filtration rate (GFR), and active TGF-β1 level, and inversely with erythrocyte sedimentation rate (ESR). In multiple regression analysis, ESR and platelet counts remained determinants of total TGF-β1. Total TGF-β1 levels were lower in patients with high disease activity (SLEDAI > 10) and severe organ damage (SLICC > 3). Significantly lower levels of total TGF-β1 were found in patients with severe renal damage, i.e. lower TGF-β1 in patients with 24-h urine protein over 3.5 g than in those with below 3.5 g (p < 0.05); lower TGF-β1 in patients with GFR less than 50 ml/min than in those with over 50 ml/min (p < 0.05). In contrast, active TGF-β1 only correlated with platelet counts. There was no association between renal damage and the levels of active TGF-β1.

CONCLUSION

This study demonstrates significantly reduced serum levels of both total and active TGF-β1 in women with SLE compared with healthy women. Total TGF-β1 levels are correlated negatively with ESR and positively with blood platelets. Total TGF-β1 levels were lower in SLE patients with high disease activity and severe organ damage. Importantly, the severity of the renal damage was associated with decreased serum levels of total TGF-β1, suggesting that TGF-β1 might be involved in pathogenesis of renal damage caused by lupus nephritis.

Effects of oestradiol and raloxifene on the induction and effector phases of experimental postmenopausal arthritis and secondary osteoporosis

Oestradiol and the selective oestrogen receptor modulator (SERM) raloxifene have been shown to ameliorate collagen-induced arthritis (CIA) in rats and in mice. One aim was to investigate if raloxifene exerts its anti-arthritic and anti-osteoporotic effects during the induction or effector phase of arthritis. A second aim was to analyse if raloxifene activates the oestrogen response element (ERE) to produce its immune-modulator effects. CIA or collagen-antibody-induced arthritis (CAIA) was induced in ovariectomized DBA/1-mice. CIA was used for evaluation of treatment during the induction, and CAIA for the effector phase of arthritis and osteoporosis development. Raloxifene, oestradiol or vehicle was administered 5 days/week. The clinical disease was evaluated continuously. Bone marrow density (BMD) was analysed with peripheral quantitative computer tomography, paws were collected for histological examination, and sera were analysed for markers of bone and cartilage turnover and proinflammatory cytokines. Transgenic luciferase (Luc)-ERE mice were immunized with collagen (CII), and after 10 days injected once with raloxifene, oestradiol or vehicle before termination. Spleens were analysed for luciferase activity to measure ERE activation. Treatment with oestradiol or raloxifene during the induction phase of CIA failed to affect arthritis. Raloxifene did not hamper disease activity in CAIA, whereas oestradiol delayed the onset and ameliorated the severity. Both raloxifene and oestradiol preserved BMD in CAIA. CII-immunization increased the oestradiol-induced ERE activation in spleen, and raloxifene activated the ERE at about 25% the intensity of oestradiol. Further experiments are needed to elucidate the exact mechanisms behind this finding.

The role of the G protein-coupled receptor GPR30 in the effects of estrogen in ovariectomized mice

In vitro studies suggest that the membrane G protein-coupled receptor GPR30 is a functional estrogen receptor (ER). The aim of the present study was to determine the possible in vivo role of GPR30 as a functional ER primarily for the regulation of skeletal parameters, including bone mass and longitudinal bone growth, but also for some other well-known estrogen-regulated parameters, including uterine weight, thymus weight, and fat mass. Three-month-old ovariectomized (OVX) GPR30-deficient mice (GPR30(-/-)) and wild-type (WT) mice were treated with either vehicle or increasing doses of estradiol (E(2); 0, 30, 70, 160, or 830 ng.mouse(-1).day(-1)). Body composition [bone mineral density (BMD), fat mass, and lean mass] was analyzed by dual-energy-X ray absorptiometry, while the cortical and trabecular bone compartments were analyzed by peripheral quantitative computerized tomography. Quantitative histological analyses were performed in the distal femur growth plate. Bone marrow cellularity and distribution were analyzed using a fluorescence-activated cell sorter. The estrogenic responses on most of the investigated parameters, including increase in bone mass (total body BMD, spine BMD, trabecular BMD, and cortical bone thickness), increase in uterine weight, thymic atrophy, fat mass reduction, and increase in bone marrow cellularity, were similar for all of the investigated E(2) doses in WT and GPR30(-/-) mice. On the other hand, E(2) treatment reduced longitudinal bone growth, reflected by decreased femur length and distal femur growth plate height, in the WT mice but not in the GPR30(-/-) mice compared with vehicle-treated mice. These in vivo findings demonstrate that GPR30 is not required for normal estrogenic responses on several major well-known estrogen-regulated parameters. In contrast, GPR30 is required for a normal estrogenic response in the growth plate.

The impact of hormone replacement therapy on humoral and cell-mediated immune responses in vivo in post-menopausal women with rheumatoid arthritis

It is well known that oestrogen has immunomodulatory properties. We have previously shown disease ameliorating effects of hormone replacement therapy (HRT) in post-menopausal women with rheumatoid arthritis (RA). The aim of this study was to investigate the effects of HRT and the patients inflammatory state on humoral and cell-mediated immune responses. Eighty-eight post-menopausal RA women were allocated to receive HRT (oestradiol and noretisterone acetate), vitamin D3 and calcium or vitamin D3 and calcium alone in a 2-year randomized controlled trial. Immunoglobulins (IgM, IgG and IgA) in serum were measured by nephelometry and rheumatoid factor (RF) concentration by enzyme-linked immunosorbent assay. Immunization with influenza vaccine was performed to quantitate humoral response to recall antigen and tuberculin skin test with purified protein derivative (PPD) to test T-cell-mediated immune response. These immune related measures were correlated with demographic and disease-related variables. HRT during 2 years did not alter concentrations of Ig, RF, IgM response to influenza vaccine or the PPD reaction. The increase in IgM against influenza vaccine was significantly positively correlated with signs of disease activity; C-reactive protein, disease activity score 28 and inversely with haemoglobin. In contrast, PPD reactivity was inversely associated with disease activity. In conclusion, long-term HRT in RA does not influence Ig or autoantibody concentrations in serum and has no significant impact on humoral and cell-mediated immune responses to recall antigens. Interestingly, high disease activity was associated to increased humoral but decreased cell-mediated immune responses irrespectively of hormone treatment.

Resistin in serum is associated with higher levels of IL-1Ra in post-menopausal women with rheumatoid arthritis

OBJECTIVES

The aim of this study was to investigate associations between serum levels of resistin, an adipokine and markers of inflammation, bone metabolism, plasma lipids and kidney function in post-menopausal RA patients and to evaluate if HRT during 2 yrs affected resistin levels.

METHODS

Eighty-eight women were randomly allocated to receive HRT, vitamin D(3) and calcium or vitamin D(3) and calcium alone. Serum levels of resistin, IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-6 soluble receptor, TNF-alpha were measured by ELISA, markers of bone metabolism, carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and carboxyterminal propeptide of type I procollagen by RIA, ESR, CRP, Hb, creatinine and lipids by standard laboratory techniques, BMD and total lean mass (TLM) by DXA and joint destruction by Larsen score. Resistin was also measured in 42 healthy control women.

RESULTS

There was no difference in resistin concentration between patients and healthy controls. Resistin was significantly correlated with IL-1Ra, CRP, TNF-alpha, ICTP, glucocorticosteroids and Larsen score and inversely with BMD, hip and with TLM. In multiple regression analysis, IL-1Ra, TLM and use of corticosteroids remained determinants of resistin. Patients treated with HRT displayed significant increase in resistin compared with controls in the first but not the second year.

CONCLUSIONS

Resistin was associated with increased inflammation, particularly by the acute-phase reactant IL-1Ra antagonizing IL-1beta, joint destruction, glucocorticosteroids and with reduced BMD and TLM. These findings suggest resistin being a significant mediator in the inflammatory process in RA. Further studies examining the mechanisms behind the relation between resistin and IL-1Ra are encouraged. HRT does not seem to have important long-term effect on resistin.

Long-term anti-arthritic and anti-osteoporotic effects of raloxifene in established experimental postmenopausal polyarthritis

Both oestrogen deficiency and the inflammatory disease contribute to the generalized bone loss seen in postmenopausal rheumatoid arthritis (RA). Oestradiol and the selective oestrogen receptor modulator raloxifene have been shown to ameliorate the disease in collagen-induced arthritis (CIA), a well-established animal model for human RA. The aim of this study was to investigate whether raloxifene-treatment would be beneficial in long-term treatment of established CIA, both regarding anti-arthritic and anti-osteoporotic properties. Female dilute brown agouti mice were ovariectomized and CIA was induced. Raloxifene or vehicle treatment was administered 5 days per week, and the clinical arthritis score was evaluated continuously. At termination, bone mineral density was analysed, paws were collected for histological examination and sera were analysed for markers of bone and cartilage turnover, as well as antibodies to type II collagen and levels of interleukin (IL)-6. Treatment with raloxifene is beneficial in long-term treatment of established CIA. It hampers the disease severity and frequency, protects the joints from destruction and protects against the development of osteoporosis. The proinflammatory cytokine IL-6 was down-regulated in raloxifene-treated mice compared with controls. The serum levels of antibodies to collagen were not affected by raloxifene-treatment. Long-term treatment with raloxifene has both anti-arthritic and anti-osteoporotic effects in established experimental postmenopausal polyarthritis.

Identification of target cells for the genomic effects of estrogens in bone

Estrogen has bone protective effects, but the exact mechanism behind these effects remains unclear. The aim of the present study was to identify the primary target cells in bone for the classical genomic effects of estrogens in vivo. For this purpose we have used reporter mice with a luciferase gene under the control of three estrogen-responsive elements (EREs), enabling detection of in vivo activation of gene transcription. Three-month-old ovariectomized mice were treated with a single dose (50 mug/kg) 17beta-estradiol (E2). Luciferase activity was analyzed in several tissues and in different bone marrow-derived lymphocyte enriched/depleted preparations using MacsMouse CD19 (for B lymphocytes) or CD90 (for T lymphocytes) MicroBeads (Miltenyi Biotec GmbH, Bergisch Gladbach, Germany). Histological characterization of cells with high luciferase content was performed using immunohistochemistry. Both cortical bone and bone marrow displayed a rapid (within 1 h) and pronounced E2-induced increase in luciferase activity. The luciferase activity in total bone marrow and in bone marrow depleted of lymphocytes was increased six to eight times more than in either B-lymphocyte or T-lymphocyte enriched cell fractions 4 h after the E2 injection, demonstrating that mature lymphocytes are not major direct targets for the genomic effect of estrogens in bone. Immunohistochemistry identified clear luciferase staining in hypertrophic growth plate chondrocytes, megakaryocytes, osteoblasts, and lining cells, whereas no staining was seen in proliferative chondrocyte. Although most of the osteocytes did not display any detectable luciferase staining, a subpopulation of osteocytes both in cortical and trabecular bone stained positive for luciferase. In conclusion, hypertrophic growth plate chondrocytes, megakaryocytes, osteoblasts, lining cells, and a subpopulation of osteocytes were identified to respond to estrogen via the classical ERE-mediated genomic pathway in bone. Furthermore, our findings indicate that possible direct estrogenic effects on the majority of osteocytes, not staining positive for luciferase, on proliferative chondrocytes and on mature lymphocytes are mediated by non-ERE actions.

17Beta-estradiol expands IgA-producing B cells in mice deficient for the mu chain

Oestrogen is not only a sex hormone but also an important regulator of the immune system. Expression of the heavy chain of IgM (mu) is essential for B-cell differentiation. However, a small number of IgA-positive B cells can be found in mice lacking the mu chain (muMT-/-). The aim of this study was to investigate the effects of oestrogen on this alternative B-cell pathway in muMT-/- mice. Our results clearly demonstrate that oestrogen increases the frequency of IgA-producing B cells in muMT-/- mice in both bone marrow and spleen cells. We also show that mature IgM-producing B cells are not required for oestrogen-mediated suppression of granulocyte-mediated inflammation or thymic involution. In conclusion, we demonstrate that 17beta-estradiol benzoate increases the frequency of IgA-producing B cells in muMT-/- mice, suggesting that oestrogen can influence the alternative B-cell pathway found in muMT-/- mice.

Prevalence and risk factors of osteoporosis in female SLE patients-extended report

OBJECTIVES

To determine the frequency of osteoporosis and possible risk factors of low bone mineral density (BMD) in women with systemic lupus erythematous (SLE) in western Sweden. In addition, to evaluate if adequate anti-osteoporotic treatment was provided.

METHODS

BMD was measured at radius, lumbar spine and hip by dual X-ray absorptiometry (DXA). An 'expected' control BMD was calculated for each patient. Simple and multiple linear regression analyses were performed to determine associations between BMD and demographic and disease-related variables.

RESULTS

One hundred and sixty-three women were included. Median age was 47 (20-82) yrs, 89 (55%) were post-menopausal and 85 (52%) were taking glucocorticosteroids. BMD was significantly reduced in all measured sites compared with expected BMD. Thirty-seven (23%), 18 (11%) and 6 (4%) of the patients were osteoporotic in at least one, two and three or more measured locations. Bisphosphonates were used by 23 (27%) of patients taking glucocorticosteroids and 13 (35%) with osteoporosis. High age and low weight or BMI were associated with low BMD in all measured sites. In total hip, high SLICC/American Collage of Rheumatology (ACR), ESR and 'combinations of DMARD' were additional markers of low BMD. High S-creatinine was associated with low BMD in lumbal spine whereas high S-creatinine and CRP were markers in radius.

CONCLUSION

Women with SLE are at greater risk of osteoporosis compared with controls and few are treated adequately. Factors associated with low BMD in SLE are high age and low weight but also markers of inflammation, impaired kidney function and disease damage, however glucocorticosteroids were not associated.

Liver-derived IGF-I is permissive for ovariectomy-induced trabecular bone loss

INTRODUCTION

Estrogen deficiency results in trabecular bone loss, associated with T-cell proliferation in the bone marrow. Insulin-like growth factor I (IGF-I) is involved in the regulation of both bone metabolism and lymphopoiesis. A major part of serum IGF-I is derived from the liver. The aim of the present study was to investigate the role of liver-derived IGF-I for ovariectomy (ovx)-induced trabecular bone loss.

MATERIALS AND METHODS

Mice with adult liver-specific IGF-I inactivation (LI-IGF-I-/-) and wild type mice (WT) were either ovx or sham operated. After 5 weeks, the skeletal phenotype was analyzed by pQCT and microCT. The bone marrow cellularity was analyzed using FACS technique, and mRNA levels were quantified using real-time PCR.

RESULTS

Ovx resulted in a pronounced reduction in trabecular bone mineral density (-52%, P < 0.001), number (-45%, P < 0.01) and thickness (-13%, P < 0.01) in WT mice while these bone parameters were unaffected by ovx in LI-IGF-I-/- mice. Furthermore, ovx increased the number of T-cells in the bone marrow of the femur in WT but not in LI-IGF-I-/- mice. Interleukin 7 (IL-7) has been reported to stimulate the formation and function of osteoclasts by inducing the expression of receptor activator of NF-kappaB ligand (RANKL) on T-cells. IL-7 mRNA levels and the RANKL/osteoprotegerin ratio in bone were increased by ovx in WT but not in LI-IGF-I-/- mice.

CONCLUSIONS

Liver-derived IGF-I is permissive for ovx-induced trabecular bone loss. Our studies indicate that IGF-I might exert this permissive action by modulation of the number of T-cells and the expression of IL-7, which in turn is of importance for the RANKL/OPG ratio and consequently osteoclastogenesis in the bone marrow.

Estrogenic agonism and antagonism of the soy isoflavone genistein in uterus, bone and lymphopoiesis in mice

The isoflavone genistein (Gen) is a naturally occurring phytoestrogen found in high concentrations in soy. The biological effects of Gen have been extensively studied. The immunomodulating properties of Gen are, however, less well investigated and the results are contradictory. Our aim was to study possible estrogen agonistic and antagonistic properties of Gen in uterus, bone, lymphopoiesis and B-cell function by comparing effects in castrated and intact female mice, respectively. Oophorectomized (OVX) and sham-operated mice were treated with s.c. doses of 17beta-estradiol (E2) (0.16 mg/kg), Gen (50 mg/kg), or vehicle (olive oil) as control. Effects on bone mineral density (BMD) were studied using peripheral quantitative computerized tomography, uterine and thymus weights were examined, lymphopoiesis in thymus and bone marrow was analyzed using flow cytometry, and the frequency of immunoglobulin-producing B cells in bone marrow and spleen was studied using an ELISPOT assay. Gen was clearly antagonizing endogenous estrogen in sham-operated female mice as shown by inhibiting the uterine weight and by increasing the frequency of B lymphopoietic cells in bone marrow. The only agonistic effect of Gen was shown by increased BMD in OVX mice. Our results are discussed in the context of estrogen receptor biology.

Estren-mediated inhibition of T lymphopoiesis is estrogen receptor-independent whereas its suppression of T cell-mediated inflammation is estrogen receptor-dependent

Estrogen has extensive effects on the immune system. The aim of the present experiments was to compare the effects of 17beta-estradiol (E2) and 4-estren-3alpha,17beta-diol (estren) on T lymphopoiesis and T cell-dependent inflammation. In order to investigate the role of estrogen receptors (ER) in the effects of E2 and estren on the immune system, ER knock-out mice lacking both ERalpha and ERbeta (DERKO) were used. T lymphopoiesis and T cell-dependent inflammation were studied by investigating thymus cellularity, the delayed-type hypersensitivity (DTH) reaction, CD4(+) T cells in spleen and serum levels of interleukin (IL)-6. As expected, the presence of ERs was mandatory for all the effects of E2. In contrast, treatment with estren reduced thymus cellularity in ER knock-out mice, indicating an effect through ER-independent pathways. Interestingly, estren suppressed only DTH, the frequency of CD4(+) T cells in spleen and serum levels of IL-6 in wild-type (WT) mice, but not in mice lacking ERs. Thus, our study is the first to show that estren inhibits T lymphopoiesis via ER-independent pathways, whereas its suppressive effects on inflammation are ER-dependent.

Influence of oestrogen receptor alpha and beta on the immune system in aged female mice

Oestrogen has a dichotomous effect on the immune system. T and B lymphopoiesis in thymus and bone marrow is suppressed, whereas antibody production is stimulated by oestrogen. In this study the importance of the oestrogen receptors (ER) ER-alpha and ER-beta in the aged immune system was investigated in 18 months old-wild type (WT), ER-alpha (ERKO), ER-beta (BERKO) and double ER-alpha and ER-beta (DERKO) knock-out mice, and compared with 4 months old WT mice. Cell phenotypes in bone marrow, spleen and thymus, and the frequency of immunoglobulin (Ig) spot forming cells (SFC) were determined. We show here that the 17-beta-oestradiol (E2)-induced downregulation of B lymphopoietic cells in bone marrow of young ovariectomized mice can be mediated through both ER-alpha and ER-beta. However, only ER-alpha is required for the age-related increased frequency of immunoglobulin M (IgM) SFC in the bone marrow, as well as for the increased production of interleukin-10 (IL-10) from cultured splenocytes in aged mice. Furthermore, increased age in WT mice resulted in lower levels of both pro- and pre-B cells but increased frequency of IgM SFC in the bone marrow, as well as increased frequency of both IgM and IgA SFC in the spleen. Results from this study provide valuable information regarding the specific functions of ER-alpha and ER-beta in the aged immune system.

Radiographic joint destruction in postmenopausal rheumatoid arthritis is strongly associated with generalised osteoporosis

OBJECTIVES

To investigate determinants of joint destruction and reduced bone mineral density (BMD) in postmenopausal women with active rheumatoid arthritis (RA) not treated with bisphosphonates or hormone replacement therapy and to evaluate if there are common markers of erosive disease and bone loss.

METHODS

BMD was measured using dual x ray absorptiometry and joint damage was examined by x ray examination according to the Larsen method in 88 patients with RA. Associations between BMD and Larsen score, and between demographic and disease related variables, including proinflammatory cytokines, HLA-DR4 epitopes, and markers of bone and cartilage turnover, were examined bivariately by simple and multiple linear regression analyses.

RESULTS

49/88 (56%) patients had osteoporosis in at least one site. Reduced BMD and increased joint destruction were associated with: at the forearm and femoral neck, high Larsen score, low weight, and old age (R(2)=0.381, p<0.001; R(2)=0.372, p<0.001, respectively); at the total hip, low weight, high Larsen score, and dose of injected glucocorticosteroids (R(2)=0.435, p<0.001); at the lumbar spine, low weight, reduced cartilage oligomeric matrix protein, and increased carboxyterminal propeptide of type I procollagen (R(2)=0.248, p<0.001). Larsen score was associated with long disease duration and increased C reactive protein (CRP) (R(2)=0.545, p<0.001).

CONCLUSIONS

Osteoporosis is common in postmenopausal patients with RA. Low weight and high Larsen score were strongly associated with BMD reduction. Increased CRP and long disease duration were determinants of erosive disease in postmenopausal women with RA. These findings indicate common mechanisms of local and generalised bone loss in RA.

Oestrogen receptor specificity in oestradiol-mediated effects on B lymphopoiesis and immunoglobulin production in male mice

Oestrogen treatment down-regulates B lymphopoiesis in the bone marrow of mice. Meanwhile it up-regulates immunoglobulin production. To understand better the oestrogen action on bone marrow male mice lacking oestrogen receptor alpha (ERalpha; ERKO mice), lacking ERbeta (BERKO mice), lacking both receptors (DERKO mice) or wild-type (wt) littermates were castrated and treated for 2.5 weeks with 30 microg/kg 17beta-oestradiol (E2) or vehicle oil as controls. The B lymphopoiesis in the bone marrow was examined by flow cytometry and mature B-cell function was studied using an ELISPOT assay enumerating the B cells in bone marrow and spleen that were actively producing immunoglobulins. In wt mice the frequency of B-lymphopoietic (B220+) cells in the bone marrow decreased from 15% to 5% upon E2 treatment. In ERKO and BERKO mice significant reduction was seen but not of the same magnitude. In DERKO mice no reduction of B lymphopoiesis was seen. In addition, our results show that E2 mediated reduction of different steps in B lymphopoiesis require only ERalpha or both receptors. In wt and BERKO mice E2 treatment resulted in significantly increased levels of B cells actively producing immunoglobulin, while in ERKO and DERKO mice no such change was seen. Similar results were found in both bone marrow and spleen. In conclusion our results clearly show that both ERalpha and ERbeta are required for complete down-regulation of B lymphopoiesis while only ERalpha is needed to up-regulate immunoglobulin production in both bone marrow and spleen.

Raloxifene- and estradiol-mediated effects on uterus, bone and B lymphocytes in mice

Raloxifene is a selective estrogen receptor modulator approved for the prevention of osteoporosis in postmenopausal women. It is selective by having estrogen-agonistic effects on bone, vessels and blood lipids while it is antagonistic on mammary and uterine tissue. Our aim was to study the agonistic and antagonistic properties of the raloxifene analogue LY117018 (LY) on uterus, bone, B lymphopoiesis and B cell function. Oophorectomized and sham-operated animals were treated with s.c. injections of equipotent anti-osteoporotic doses of 17beta-estradiol (E2) (0.1 mg/kg) or LY (3 mg/kg) or vehicle as controls. Effects on bone mineral density (BMD) were studied using peripheral quantitative computed tomography, uterine weight was examined, B lymphopoiesis was examined using flow cytometry and B cell function in bone marrow and spleen was studied by the use of an ELISPOT assay. E2 and LY had similar effects on BMD and bone marrow B lymphopoiesis, while LY had a clear antagonistic effect on endogenous estrogen in uterine tissue and no stimulating effect on the frequency of Ig-producing B cells in sham-operated animals. Our results are discussed in the context of estrogen receptor biology, relations between the immune system and bone metabolism and also with respect to the estrogen-mediated effects on rheumatic diseases.

Estrogen receptor specificity for the effects of estrogen in ovariectomized mice

Estrogen exerts a variety of important physiological effects, which have been suggested to be mediated via the two known estrogen receptors (ERs), alpha and beta. Three-month-old ovariectomized mice, lacking one or both of the two estrogen receptors, were given estrogen subcutaneously (2.3 micro g/mouse per day) and the effects on different estrogen-responsive parameters, including skeletal effects, were studied. We found that estrogen increased the cortical bone dimensions in both wild-type (WT) and double ER knockout (DERKO) mice. DNA microarray analysis was performed to characterize this effect on cortical bone and it identified four genes that were regulated by estrogen in both WT and DERKO mice. The effect of estrogen on cortical bone in DERKO mice might either be due to remaining ERalpha activity or represent an ERalpha/ERbeta-independent effect. Other effects of estrogen, such as increased trabecular bone mineral density, thymic atrophy, fat reduction and increased uterine weight, were mainly ERalpha mediated.

Estrogen receptor alpha, but not estrogen receptor beta, is involved in the regulation of the OPG/RANKL (osteoprotegerin/receptor activator of NF-kappa B ligand) ratio and serum interleukin-6 in male mice

Estrogens are important for the male skeleton. Osteoprotegerin (OPG), receptor activator of NF-kappa B ligand (RANKL), interleukin-6 (IL-6), IL-1 and tumor necrosis factor alpha (TNFalpha) have been suggested to be involved in the skeletal effects of estrogen. We treated orchidectomized mice with estradiol for 2 weeks and observed a 143% increase in the trabecular bone mineral density of the distal metaphysis of femur that was associated with a decreased OPG/RANKL mRNA ratio in vertebral bone. A similar decreased OPG/RANKL ratio was also seen after estrogen treatment of ovariectomized female mice. The effect of estrogen receptor (ER) inactivation on the OPG/RANKL ratio was dissected by using intact male mice lacking ER alpha (ERKO), ER beta (BERKO) or both receptors (DERKO). The expression of OPG was increased in ERKO and DERKO but not in BERKO male mice, resulting in an increased OPG/RANKL ratio. Furthermore, serum levels of IL-6 and tartrate-resistant acid phosphatase 5b (TRAP 5b) were decreased in ERKO and DERKO, but not in BERKO male mice. These results demonstrate that ER alpha, but not ER beta, is involved in the regulation of the vertebral OPG/RANKL ratio, serum levels of IL-6 and TRAP 5b in male mice.

Inosine monophosphate dehydrogenase (IMPDH) inhibition in vitro suppresses lymphocyte proliferation and the production of immunoglobulins, autoantibodies and cytokines in splenocytes from MRLlpr/lpr mice

The aim of this study was to evaluate the effects of the immunomodulating drug mycophenolic acid (MPA) on splenocytes in an animal model of systemic lupus erythematosus (SLE), using MRLlpr/lpr mice. MPA reversibly inhibits inosine 5'-monophosphate dehydrogenase, an enzyme involved in the de novo guanosine synthesis. Splenocytes were treated with MPA (at 1 or 10 microM), and stimulated with either lipopolysaccharide (LPS; 10 microg/ml) or concanavalin A (ConA; 1.25 microg/ml). In blocking experiments, guanosine (100 microM) was added to the cultures to inhibit the effects of MPA. Lymphocyte proliferation, enumeration of immunoglobulin producing cells (using ELISPOT) and quantification of anti-double-stranded (ds) DNA antibodies, IFN-gamma and IL-10 (by ELISA) in supernatants were performed. In addition, cell viability was evaluated using propidium iodide and flow cytometry. We found that MPA-treated splenocytes had dramatically decreased mitogen-induced proliferation and number of immunoglobulin producing cells, down-regulated production of IFN-gamma, IL-10 and IgM anti-dsDNA antibodies. The viability of MPA-treated cells was also decreased. All of the effect modulated by MPA could be neutralized by the addition of guanosine. We conclude that MPA has potent immunomodulating effects on both B and T lymphocytes, modulating not only proliferation, but also the production of cytokines, immunoglobulins and autoantibodies.

Role of oestrogen receptors alpha and beta in immune organ development and in oestrogen-mediated effects on thymus

Oestrogens affect the development and regulation of the immune system. To determine the role of oestrogen receptors alpha (ER-alpha) and beta (ER-beta) on the development of the immune system, male ER-alpha (ERKO) and ER-beta (BERKO) mice, as well as alphabeta-double knockout (DERKO) mice, were studied. Deletion of ER-alpha led to hypoplasia of both thymus and spleen. Interestingly, a higher frequency of immature double CD4+ CD8+ thymocytes was found in ER-alpha(-) mice compared with ER-alpha(+) mice. Female oophorectomized BERKO mice given oestradiol (E2) displayed a similar degree of thymic atrophy compared with the wild-type strain but showed only limited involution of thymus cortex and no alteration of thymic CD4/CD8 phenotype expression. Our data demonstrate that expression of ER-alpha, but not ER-beta, is mandatory in males for development of full-size thymus and spleen, whereas expression of ER-beta is required for E2-mediated thymic cortex atrophy and thymocyte phenotype shift in females. A potential background for the above findings may be down-regulated activity in the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis in males lacking ER-alpha and suppressed sensitivity of females lacking ER-beta to E2-mediated suppression of IGF-1.

Intrathecal cytokines in systemic lupus erythematosus with central nervous system involvement

Symptoms originating from central nervous system (CNS) are frequently occuring in patients with systemic lupus erythematosus (SLE). Reliable diagnostic markers for this condition are presently lacking. Importantly, CNS involvement in lupus patients is associated with increased morbidity and mortality. The aim of this retrospective evaluate was to study the diagnostic value of cerebrospinal fluid (CSF) cytokine levels in SLE patients with CNS involvement. 34 patients with SLE were hospitalized and investigated for the presence of CNS lupus. These patients were evaluated clinically and with magnetic resonance imaging (MRI) and CSF analyses, as well as with neuropsychiatric tests. 13 patients were found to have CNS lupus whereas another four of the patients fulfilled the criteria for CNS involvement but were excluded from this group due to other causes of CNS involvement. Lastly, in 17 SLE cases, the diagnosis of CNS lupus could not be confirmed. CSF levels of interleukin-6 (IL-6) and IL-8, as well as the CSF/serum IL-6 ratio, were elevated in the CNS lupus group, compared with the 17 SLE patients not fullfilling a diagnosis of cerebral lupus. Interestingly, follow-up of five patients being successfully treated for CNS lupus revealed profound decrease of intrathecal IL-6 levels. These results indicate that analysis of CSF cytokine levels, especially IL-6 and IL-8, may be useful in the diagnostics and possibly follow-up of SLE patients with cerebral lupus.

Effects of raloxifene, a selective estrogen receptor modulator, on thymus, T cell reactivity, and inflammation in mice

Raloxifene is a selective estrogen receptor modulator approved for prevention of osteoporosis in postmenopausal women. It is selective by virtue of having estrogen agonistic effects in bone, vessels, and blood lipids, while it is antagonistic with mammary and uterine tissue. The aim of the study was to examine whether the raloxifene analogue LY117018 (LY) has estrogenic effects on the thymus, T cell responsiveness, and inflammation. Oophorectomized normal mice were treated with subcutaneous injections of equipotent antiosteoporotic doses of LY (3 mg/kg) and 17beta-estradiol (E2) (0.1 mg/kg) or vehicle as controls. Effects on thymus were studied by analyses of thymus weight, cellularity, and CD4 and CD8 phenotype expression and histology, while inflammation was determined as T-cell-mediated delayed-type hypersensitivity (DTH) and granulocyte-mediated footpad swelling. LY lacked the suppressive properties of E2 on DTH and granulocyte-mediated inflammation. Furthermore, LY induced only minor thymus atrophy compared with E2 and did not, in contrast to E2, alter the thymic CD4/CD8 phenotypes. These results clearly demonstrate that raloxifene principally lacks the modulatory effects of estrogen on T cell responsiveness and inflammation. Our data are discussed in the context of recent findings in estrogen receptor biology and also with respect to estrogen-mediated alteration of autoimmune rheumatic diseases.

Action of dexamethasone in the suppression of delayed-type hypersensitivity in reconstituted SCID mice

OBJECTIVE AND DESIGN

It is not known whether the amelioration of inflammation by corticosteroids is mediated through a direct effect on the T cells or by effects on other inflammatory cells and/or their products. To explore the mechanisms whereby corticosteroids exert their effects on T cell dependent inflammation we have used severe combined immunodeficiency (SCID) mice. These mice are largely devoid of functional T and B lymphocytes, hence being unable to raise delayed type hypersensitivity (DTH), but display intact antigen presenting capacity. The aim of this study was to analyse the target cell population participating in DTH and being affected by corticosteroid treatment.

MATERIALS AND METHODS

SCID mice were reconstituted with naive thymocytes from congeneic C.B-17 mice. The day after cell transfer, recipient SCID mice were sensitised by epicutaneous application with oxazolone (OXA). One week later all the mice were challenged with OXA and DTH reaction was registered. Recipient SCID mice were administered a single dose of Dexamethasone (Dex) either one day before cell transfer or one day before the challenge. A group of donor mice was treated with Dex prior to cell preparation for transfer. Also intact C57B1/6 (B6) mice were treated with corticosteroids either before sensitisation or before challenge.

RESULTS

In B6 mice, a single injection of Dex significantly decreased DTH when given one day before challenge but had no effect when given one day before sensitisation. In SCID mice treated with various doses of Dex one day before challenge, a profound depression (P < 0.01-0.001) of DTH reactivity was observed, compared to controls. In contrast, administration of Dex to recipient SCID mice before cell transfer resulted in an increased rather than decreased DTH response among SCID recipients. SCID mice receiving Dex exposed thymocytes displayed no significant differences in DTH response, compared to the controls.

CONCLUSIONS

Our results indicate that corticosteroids exert suppressive impact on the effector phase of DTH response in mice by anti-inflammatory properties of the hormone or by effects on OXA-sensitised memory T cells.

Mycophenolate mofetil ameliorates perivascular T lymphocyte inflammation and reduces the double-negative T cell population in SLE-prone MRLlpr/lpr mice

Effects on T lymphocyte mediated pathology, phenotypes, and functions in MRLlpr/lpr mice given mycophenolate mofetil (MMF) (100 mg/kg/day) via drinking water or controls given ip cyclophosphamide (CYC) injections (1.8 mg/mouse/week) or water were described. Both MMF and CYC treatment diminished kidney and large salivary gland perivascular cell infiltrates, reduced profoundly double-negative (DN) T cell frequencies, decreased total lymphocyte number in spleen, and increased in vitro proliferative response to Con A. IFN-gamma and IL-10 in supernatants from Con A stimulated spleen cells were augmented after MMF but not CYC treatment. MMF treatment increased whereas CYC reduced IL-12 in serum. Kidney expressions of IFN-gamma, IL-10, and IL-12 mRNA were unaffected by MMF but decreased by CYC. Our results demonstrate that MMF and CYC suppress perivascular T lymphocyte inflammation by reducing the DN T cell population and by amelioration of T cell function. The varying cytokine patterns suggest different mechanisms of the two drugs.

Beneficial effect of the inosine monophosphate dehydrogenase inhibitor mycophenolate mofetil on survival and severity of glomerulonephritis in systemic lupus erythematosus (SLE)-prone MRLlpr/lpr mice

The aim of the present study was to evaluate the therapeutic effect of mycophenolate mofetil (MMF) on the course of disease in SLE-prone MRLlpr/lpr mice. Three-months-old mice displaying clinical symptoms of glomerulonephritis were given MMF (100 mg/kg per day) orally via the drinking water. Control mice received i.p. injections of cyclophosphamide (CYC) (1.8 mg/mouse per week) or saline. Survival, albuminuria and haematuria, immunoglobulin levels and anti-dsDNA antibodies in serum, frequencies of immunoglobulin-producing B lymphocytes and glomerular deposits of immunoglobulin and C3 were analysed. The results showed that MMF treatment significantly prolonged survival and reduced the occurrence of albuminuria and haematuria in MRLlpr/lpr mice. In addition, the number of immunoglobulin-producing B cells and serum levels of IgG and IgG anti-dsDNA antibodies were reduced after MMF and CYC treatment. MMF treatment significantly reduced the extent of deposition of C3 in glomeruli. We conclude that the reduced severity of glomerulonephritis following treatment of lupus-prone mice with MMF was as efficacious as that of CYC. These results warrant clinical trials of MMF in SLE patients with glomerulonephritis.

T lymphocytes are not the target for estradiol-mediated suppression of DTH in reconstituted female severe combined immunodeficient (SCID) mice

Oestrogen has the capacity to suppress T cell-dependent DTH. To explore the mechanisms whereby oestrogen exerts its effects on the immune system we have used SCID mice which are largely devoid of functional T and B lymphocytes, hence being unable to raise DTH, but display intact antigen-presenting capacity. Transfer of lymphocytes to SCID mice restores the DTH capacity. In order to analyse if oestrogen down-regulates DTH by a direct action on T cells we reconstituted SCID mice with either splenocytes or thymocytes from congenic C.B-17 or allogeneic B6 donor mice. Either donor or recipient mice were exposed to estradiol before cell transfer. DTH response was registered in recipient SCID mice 1 and 3 weeks after challenge with oxazolone (OXA). SCID mice receiving estradiol-exposed spleen cells from congenic or allogeneic donor mice displayed lower DTH responses compared with control mice. In contrast, SCID mice receiving estradiol-exposed thymocytes from congenic donor mice showed no significant difference in DTH response compared with control mice. Estradiol-treated SCID mice, transferred with either spleen cells or thymocytes from congenic, hormonally non-treated donors, displayed a significantly lower DTH response compared with control mice. In contrast, estradiol-treated SCID mice receiving hormonally non-treated allogeneic spleen cells showed no difference in DTH response compared with control mice. The results show that T lymphocytes are not the target cell population for estradiol-mediated suppression of DTH in reconstituted female SCID mice.

Expression of the mucosal lymphocyte integrin alphaEbeta7 and its ligand E-cadherin in salivary glands of patients with Sjögren's syndrome

The expression of the mucosal lymphocyte integrin alphaEbeta7 and its ligand E-cadherin was analyzed in sialadenitic lesions of patients with Sjögren's syndrome in order to assess the potential interactions between the mucosal and the systemic immunological compartments. Immunohistochemical evaluation of the inflammatory infiltrates in the salivary gland tissues in Sjögren's syndrome patients revealed presence of alphaEbeta7-integrin-expressing lymphocytes, in 18 of 20 biopsies examined. The ligand for alphaEbeta7, E-cadherin was also found in 18 of 20 salivary gland biopsies analysed. These results suggest homing of lymphocytes derived from the gut epithelium through the blood stream to inflamed salivary gland tissue followed by in situ interaction with E-cadherin expressing cells, the ligand for alphaEbeta7 expressing T lymphocytes.