Malin C. Erlandsson

Role of oestrogen receptors α and β 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 α (ER‐α) and β (ER‐β) on the development of the immune system, male ER‐α (ERKO) and ER‐β (BERKO) mice, as well as αβ‐double knockout (DERKO) mice, were studied. Deletion of ER‐α led to hypoplasia of both thymus and spleen. Interestingly, a higher frequency of immature double CD4+ CD8+ thymocytes was found in ER‐α− mice compared with ER‐α+ 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‐α, but not ER‐β, is mandatory in males for development of full‐size thymus and spleen, whereas expression of ER‐β 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‐α and suppressed sensitivity of females lacking ER‐β to E2‐mediated suppression of IGF‐1.

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 α (ERα; ERKO mice), lacking ERβ (BERKO mice), lacking both receptors (DERKO mice) or wild‐type (wt) littermates were castrated and treated for 2·5 weeks with 30 μg/kg 17β‐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 ERα 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 ERα and ERβ are required for complete down‐regulation of B lymphopoiesis while only ERα is needed to up‐regulate immunoglobulin production in both bone marrow and spleen.

Influence of oestrogen receptor α and β 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‐α and ER‐β in the aged immune system was investigated in 18 months old‐wild type (WT), ER‐α (ERKO), ER‐β (BERKO) and double ER‐α and ER‐β (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‐β‐oestradiol (E2)‐induced downregulation of B lymphopoietic cells in bone marrow of young ovariectomized mice can be mediated through both ER‐α and ER‐β. However, only ER‐α 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‐α and ER‐β in the aged immune system.

Osteoporosis in experimental postmenopausal polyarthritis: the relative contributions of estrogen deficiency and inflammation

Generalized osteoporosis in postmenopausal rheumatoid arthritis (RA) is caused both by estrogen deficiency and by the inflammatory disease. The relative importance of each of these factors is unknown. The aim of this study was to establish a murine model of osteoporosis in postmenopausal RA, and to evaluate the relative importance and mechanisms of menopause and arthritis-related osteoporosis. To mimic postmenopausal RA, DBA/1 mice were ovariectomized, followed by the induction of type II collagen-induced arthritis. After the mice had been killed, paws were collected for histology, one femur for bone mineral density (BMD) and sera for analyses of markers of bone resorption (RatLaps; type I collagen cross-links, bone formation (osteocalcin) and cartilage destruction (cartilage oligomeric matrix protein), and for the evaluation of antigen-specific and innate immune responsiveness. Ovariectomized mice displayed more severe arthritis than sham-operated controls. At termination of the experiment, arthritic control mice and non-arthritic ovariectomized mice displayed trabecular bone losses of 26% and 22%, respectively. Ovariectomized mice with arthritis had as much as 58% decrease in trabecular BMD. Interestingly, cortical BMD was decreased by arthritis but was not affected by hormonal status. In addition, markers of bone resorption and cartilage destruction were increased in arthritic mice, whereas markers of bone formation were increased in ovariectomized mice. This study demonstrates that the loss of endogenous estrogen and inflammation contribute additively and equally to osteoporosis in experimental postmenopausal polyarthritis. Markers of bone remodeling and bone marrow lymphocyte phenotypes indicate different mechanisms for the development of osteoporosis caused by ovariectomy and arthritis in this model.

Inhibition of fms-like tyrosine kinase 3 alleviates experimental arthritis by reducing formation of dendritic cells and antigen presentation

TKs are intracellular signaling molecules essential for cell homeostasis. Inhibition of TKs is used in treatment of malignancies and diabetes mellitus. The present study evaluated the role of Flt3 in antigen‐induced arthritis. Mice were immunized with mBSA, and arthritis was induced by an i.a. injection of mBSA. Treatment with the Flt3 inhibitor sunitinib was started together with mBSA immunization or together with the induction of arthritis. The mBSA‐injected joints were evaluated morphologically for signs of synovitis and bone/cartilage destruction. Markers of bone metabolism and antibody responses were measured by ELISA. Maturation of DCs in the bone marrow and spleen was evaluated by flow cytometry. Sunitinib treatment reduced the intensity of synovitis and the incidence of bone destruction. The reduction in bone destruction was seen when the treatment was started at the time of immunization or at the time of arthritis induction. The antiarthritic effect was achieved by inhibition of DCs, reduction of antibody production, and bone metabolism. Inhibition of Flt3 is a potent antiarthritic mechanism reducing antigen presentation, synovial inflammation, and bone resorption. Down‐regulation of TKs may be a useful tool in the treatment of human RA.

Activation of Fms-Like Tyrosine Kinase 3 Signaling Enhances Survivin Expression in a Mouse Model of Rheumatoid Arthritis

Survivin is known as an inhibitor of apoptosis and a positive regulator of cell division. We have recently identified survivin as a predictor of joint destruction in patients with rheumatoid arthritis (RA). Flt3 ligand (Flt3L) is expressed in the inflamed joints and has adjuvant properties in arthritis. Studies on 90 RA patients (median age 60.5 years [range, 24–87], disease duration 10.5 years [range, 0–35]) show a strong positive association between the levels of survivin and Flt3L in blood. Here, we present experimental evidence connecting survivin and Flt3L signaling. Treatment of BALB/c mice with Flt3L led to an increase of survivin in the bone marrow and in splenic dendritic cells. Flt3L changed the profile of survivin splice variants, increasing transcription of the short survivin40 in the bone marrow. Treatment with an Flt3 inhibitor reduced total survivin expression in bone marrow and in the dendritic cell population in spleen. Inhibition of survivin transcription in mice, by shRNA lentiviral constructs, reduced the gene expression of Flt3L. We conclude that expression of survivin is a downstream event of Flt3 signaling, which serves as an essential mechanism supporting survival of leukocytes during their differentiation, and maturation of dendritic cells, in RA.

Changes in pain and insulin-like growth factor 1 in fibromyalgia during exercise: the involvement of cerebrospinal inflammatory factors and neuropeptides

AbstractIntroductionFibromyalgia (FM) is characterized by chronic pain. Impaired growth hormone responses and reduced serum insulin-like growth factor 1 (IGF-1) are common in FM. The aim was to examine changes in serum IGF-1, cerebrospinal fluid (CSF), neuropeptides, and cytokines during aerobic exercise in FM patients.MethodsIn total, 49 patients (median age, 52 years) with FM were included in the study. They were randomized to either the moderate- to high-intensity Nordic Walking (NW) program (n = 26) or the supervised low-intensity walking (LIW) program (n = 23). Patients participated in blood tests before and after 15 weeks of aerobic exercise. Changes in serum levels of free IGF-1, pain rating on a 0- to 100-mm scale, pain threshold, and 6-minute walk test (6MWT) were examined. CSF, neuropeptides, matrix metalloproteinase 3 (MMP-3), and inflammatory cytokines were determined. Nonparametric tests were used for group comparisons and correlation analyses.ResultsSerum free IGF-1 levels did not change during 15 weeks of exercise between the two groups, although the 6MWT significantly improved in the NW group (p = 0.033) when compared with LIW. Pain did not significantly change in any of the groups, but tended to decrease (p = 0.052) over time in the total group. A tendency toward a correlation was noted between baseline IGF-1 and a decrease of pain in response to exercise (r = 0.278; p = 0.059). When adjusted for age, this tendency disappeared. The change in serum free IGF-1 correlated positively with an alteration in CSF substance P (SP) levels (rs= 0.495; p = 0.072), neuropeptide Y (NPY) (rs = 0.802; p = 0.001), and pain threshold (rs = 0.276; p = 0.058). Differing CSF SP levels correlated positively to a change in pain threshold (rs= 0.600; p = 0.023), whereas the shift in CSF MMP-3 inversely correlated with an altered pain threshold (rs= -0.569; p = 0.034).ConclusionsThe baseline level of serum free IGF-1 did not change during high or low intensity of aerobic exercise. Changes in IGF-1 correlated positively with a variation in CSF SP, NPY, and pain threshold. These data indicate a beneficial role of IGF-1 during exercise in FM.Trial registration: ClinicalTrials.gov NCT00643006.

Estrogen regulates T helper 17 phenotype and localization in experimental autoimmune arthritis

IntroductionThe incidence and progression of many autoimmune diseases are sex-biased, which might be explained by the immunomodulating properties of endocrine hormones. Treatment with estradiol potently inhibits experimental autoimmune arthritis. Interleukin-17-producing T helper cells (Th17) are key players in several autoimmune diseases, particularly in rheumatoid arthritis. The aim of this study was to investigate the effects of estrogen on Th17 cells in experimental arthritis.MethodsOvariectomized DBA/1 mice treated with 17β-estradiol (E2) or placebo were subjected to collagen-induced arthritis (CIA), and arthritis development was assessed. Th17 cells in joints and lymph nodes were studied by flow cytometry. Lymph node Th17 cells were also examined in ovariectomized estrogen receptor α–knockout mice (ERα−/−) and wild-type littermates, treated with E2 or placebo and subjected to antigen-induced arthritis.ResultsE2-treated mice with established CIA showed reduced severity of arthritis and fewer Th17 cells in joints compared with controls. Interestingly, E2-treated mice displayed increased Th17 cells in lymph nodes during the early phase of the disease, dependent on ERα. E2 increased the expression of C-C chemokine receptor 6 (CCR6) on lymph node Th17 cells as well as the expression of the corresponding C-C chemokine ligand 20 (CCL20) within lymph nodes.ConclusionsThis is the first study in which the effects of E2 on Th17 cells have been characterized in experimental autoimmune arthritis. We report that E2 treatment results in an increase of Th17 cells in lymph nodes during the early phase of arthritis development, but leads to a decrease of Th17 in joints during established arthritis. Our data suggest that this may be caused by interference with the CCR6-CCL20 pathway, which is important for Th17 cell migration. This study contributes to the understanding of the role of estrogen in the development of autoimmune arthritis and opens up new fields for research concerning the sex bias in autoimmune disease.

Fms-like tyrosine kinase 3 ligand controls formation of regulatory T cells in autoimmune arthritis.

Fms-like tyrosine kinase 3 ligand (Flt3L) is known as the primary differentiation and survival factor for dendritic cells (DCs). Furthermore, Flt3L is involved in the homeostatic feedback loop between DCs and regulatory T cell (Treg). We have previously shown that Flt3L accumulates in the synovial fluid in rheumatoid arthritis (RA) and that local exposure to Flt3L aggravates arthritis in mice, suggesting a possible involvement in RA pathogenesis. In the present study we investigated the role of Flt3L on DC populations, Tregs as well as inflammatory responses in experimental antigen-induced arthritis. Arthritis was induced in mBSA-immunized mice by local knee injection of mBSA and Flt3L was provided by daily intraperitoneal injections. Flow cytometry analysis of spleen and lymph nodes revealed an increased formation of DCs and subsequently Tregs in mice treated with Flt3L. Flt3L-treatment was also associated with a reduced production of mBSA specific antibodies and reduced levels of the pro-inflammatory cytokines IL-6 and TNF-α. Morphological evaluation of mBSA injected joints revealed reduced joint destruction in Flt3L treated mice. The role of DCs in mBSA arthritis was further challenged in an adoptive transfer experiment. Transfer of DCs in combination with T-cells from mBSA immunized mice, predisposed naïve recipients for arthritis and production of mBSA specific antibodies. We provide experimental evidence that Flt3L has potent immunoregulatory properties. Flt3L facilitates formation of Treg cells and by this mechanism reduces severity of antigen-induced arthritis in mice. We suggest that high systemic levels of Flt3L have potential to modulate autoreactivity and autoimmunity.

High Survivin Levels Predict Poor Clinical Response to Infliximab Treatment in Patients with Rheumatoid Arthritis

OBJECTIVE To evaluate if the measurement of survivin in the blood of patients with rheumatoid arthritis (RA) undergoing infliximab treatment has predictive value for treatment response. METHODS The study included 87 consecutive RA patients (age 24-89 years, disease duration 18-526 months) treated with regular infusions of influximab. Survivin levels were measured by enzyme-linked immunosorbent assay and evaluated in relation to the total dose of infliximab, disease activity (DAS28), response to infliximab treatment (change in DAS28 >1.2), and radiographic damage (vdH-Sharp score). RESULTS Thirty-seven percent of patients were survivin-positive (survivin >0.9 ng/mL) and showed severe radiographic damage at the start of infliximab treatment compared with survivin-negative (P = 0.027). Patients with high survivin levels were unlikely to respond to infliximab treatment (OR 4.02 [1.22-14.61], P = 0.022) and achieve remission (OR 4.32[1.01-30.11], P = 0.048) compared with patients with low survivin levels. CONCLUSIONS High survivin levels are associated with severe radiographic damage at the start of treatment and a poor response to infliximab. Survivin measurement should be considered an additional tool for aiding the selection and follow-up of antirheumatic treatment.