Female Preponderance for Development of Arthritis in Rats is Influenced by both Sex Chromosomes and Sex Steroids

Autoimmune arthritis was induced after a single injection of the non-immunogenic adjuvant (avridine) or with autologous rat type II collagen. Females of two different rat strains, DA and LEW, were found to be more susceptible than males. To investigate further the mechanisms behind the female preponderance, we selected the avridine induced arthritis model. This is known to be a chronic jointspecific disease which is T-cell dependent and associated with MHC genes and, therefore, is an appropriate model for rheumatoid arthritis. To address the possibility of sex chromosome involvement, reciprocal F1 hybrids were produced. Female (DAxLEW)_F1 rats were found to be more prone to arthritis than their male counterparts. This difference could be explained, at least partly, by the influence of sex chromosomes since reciprocal (LEWXDA)_F1 rats showed no sex linkage. However, the sex linkage was more pronounced in normal rats when compared to castrated (DAxLEW)_F1, rats indicating a role for sex hormones in conjunction with the sex chromosome-linked effect. Both oestrogen and testosterone had a suppressive effect on the development of arthritis. The findings presented here suggest the presence of a sex chromosome gene, which mediates its function only in the presence of sex hormones and is associated with a female preponderance for development of arthritis.     

Estrogen induced suppression of collagen arthritis. V: Physiological level of estrogen in DBA/1 mice is therapeutic on established arthritis, suppresses anti-type II collagen T-cell dependent immunity and stimulates polyclonal B-cell activity

Immunization of castrated female DBA/1 mice with rat type II collagen (CII) induces severe polyarthritis with an onset 3-5 weeks after immunization and with 80-100% incidence. Estrogen treatment, inducing physiological 17 beta-estradiol (E2) levels, during a limited period before and after the immunization, or during another period before the expected onset of arthritis, delayed the arthritic onset by approximately 10 days but did not affect the incidence of severity of arthritis. Treatment with physiological doses of E2 after onset of arthritis decreased severity and duration of disease. The T-cell dependent anti-CII autoantibody response was suppressed if the E2 treatment was given immediately before and after CII immunization and was not significantly affected if E2 treatment was given after CII immunization. Neither the total anti-CII Ig levels nor the anti-CII IgG2a levels correlated with development of arthritis. We also titrated the serum levels of estrogen and recorded the vaginal smear response after injections of various doses of E2. This enabled us to work in a physiological range of estrogen levels, spanning the levels found at the end of pregnancy and those found during the normal estrous cycle. These levels were found to suppress antigen-specific T-cell functions but enhance certain B-cell activities since the delayed type hypersensitivity (DTH) reaction against CII was suppressed while the total number of splenic Ig-secreting cells increased. These findings suggest that estrogen in physiological doses is therapeutic for the development of collagen-induced arthritis and that estrogen exerts dualistic effects on the immune system by suppressing T-cell functions and stimulating certain B-cell activities. The suppressive effect on arthritis could not be explained by suppression of anti-CII autoantibody response and must therefore depend on other T-cell-mediated functions.     

Oestrogen induced suppression of collagen arthritis: I. Long term oestradiol treatment of DBA/1 mice reduces severity and incidence of arthritis and decreases the anti type II collagen immune response.

Experimental animal models can be used to help understand how oestrogen modulates autoimmune arthritis. We have previously shown that castration of female DBA/1 mice exaggerates arthritis induced with type II collagen. This report shows that treatment of castrated DBA/1 mice with low doses (0.2 micrograms twice a week) of beta-oestradiol reduces the incidence (37% vs 78% in controls) and severity (3.9 vs 5.6 mean scores) of arthritis. Levels of IgG anti type II collagen antibodies are decreased whereas levels of IgM antibodies are increased in the beta-oestradiol treated mice. The T cell response, as measured by a 3H-thymidine assay, is reduced in the beta-oestradiol treated mice. The results suggest that treatment with low doses of beta-oestradiol exerts a suppressive effect on both development of collagen arthritis as well as T cell dependent immune reactivity towards type II collagen.     

Oestrogen-Induced Suppression of Collagen Arthritis

Immunization of female Lewis rats with bovine type II collagen induces a severe polyarthritis with an incomplete penetration. Castration of the rats increased the incidence to 94% compared with 50% among sham-operated controls. When castrated female rats were implanted with silicone capsules containing beta-oestradiol they developed arthritis with a delayed onset and a decreased severity compared with castrated rats implanted with empty Silastic capsules. The levels of anti-type II collagen auto-antibodies were not affected by castration or oestrogen treatment. These findings show that oestrogen suppresses the development of collagen arthritis in rats and that this effect is mediated by mechanisms other than anti-type II collagen auto-antibodies.     

Differential effects of oestrogen in murine lupus: acceleration of glomerulonephritis and amelioration of T cell-mediated lesions.

Oestrogen is known to accelerate glomerulonephritis and autoantibody production in human and murine systemic lupus erythematosus (SLE). In this study we demonstrate that treatment of castrated autoimmune MRL +/+ mice with physiological doses of oestrogen results in enhanced immunoglobulin and autoantibody production as well as increased deposition of IgG in renal glomeruli. Accelerated development of glomerulonephritis was also evident from the increase of albuminuria. Interestingly, in contrast to these deteriorative effects of oestrogen on immune complex-mediated disease we now show that the lymphocytic infiltrations in the submandibular glands and perivascular lesions in the kidneys were significantly diminished after exposure to oestrogen. This remarkable impact of physiological oestrogen levels on the outcome of SLE in MRL +/+ mice is postulated to be the result of a differential effect on T and B cell-mediated immune responses.     

Oestrogen-Mediated Suppression of Collagen-Induced Arthritis in Rats

Administration of oestrogen to castrated female rats has previously been shown to exert a suppressive effect both on the development of collagen-induced arthritis (CIA) and on the delayed-type hypersensitivity (DTH) reaction to collagen II (CII). The present study is concerned with the mechanisms responsible for this suppression, particularly as to the role of the thymus and the CD8+ T lymphocytes; both the thymic epithelial cells and the CD8+ T cells have earlier been implicated as responsible for oestrogen-mediated immunomodulation on the basis of their expression of oestrogen receptors. Adult thymectomy alone did not affect either the incidence or severity of arthritis. Furthermore, adult thymectomy did not change the observed suppressive effects of oestrogen treatment on arthritis development or auto-anti-CII T-cell immunity. Elimination of CD8+ T cells was subsequently achieved in groups of thymectomized rats by utilizing the fact that efficient depletion of CD8+ T cells occurs after in vivo treatment with OX8 monoclonal antibodies; depletion of peripheral CD8+ T cells failed to influence the suppressive effect of oestrogen on CIA and on the in vitro proliferative response of lymph-node cells to CII. Depletion of CD8+ T cells did, however, in itself reduce the incidence of CIA in non-oestrogen-treated and thymectomized rats. We conclude that oestrogen may exert its suppressive effect on development of CIA and on T-cell responsiveness via mechanisms independent of both the thymus and the CD8+ T-cell subpopulation, but that CD8+ T cells are nevertheless involved in the regulation and/or effectuation of the immune reactions responsible for development of collagen arthritis in rats.     

Histocompatibility Complex Gene Products and Exposure to Oestrogen: Two Independent Disease Accelerating Factors in Murine Lupus

A number of studies have demonstrated that oestrogen exerts a significant impact on the course of experimental autoimmune diseases. Exposure to oestrogen aggravates SLE glomerulonephritis whereas the opposite outcome has been demonstrated in experimental arthritis, vasculitis, thyroiditis, and sialadenitis. In this report we have analysed the respective impact of H-2^z linked gene products and long-term treatment with physiological doses of oestradiol on clinical and immunological variables in castrated backcrosses of lupus prone NZB/W and NZB mice. Our results demonstrate that H-2^z linked gene products accelerate B-cell activation and stimulate autoantibody production resulting in aggravation of glomerulonephritis and precocious death in renal failure. These H-2^z linked gene products do not influence T-cell mediated sialadenitis. Irrespectively of the H-2 haplotype of the mice, administration of oestrogen resulted in intense polyclonal B cell activation and aggravation of glomerulonephritis. However, exposure to oestrogen resulted in amelioration of sialadenitis. Notably, our result indicates that B-cell activation achieved by oestrogen and H-2^z gene linked products, respectively is mediated by independent mechanisms. In addition, we have developed a predictive in vivo test that permits forecasts regarding efficiency of oestrogen treatment for suppression of T-cell mediated lesions. Using this test procedure in young, clinically healthy SLE mice we have been able to prove that animals displaying suppressed delayed type hypersensitivity (DTH) after short-term oestrogen exposure showed significantly lower long-term morbidity regarding development of sialadenitis upon continuous treatment with physiological doses of oestradiol.     

Both common and unique susceptibility genes in different rat strains with pristane-induced arthritis

Pristane-induced arthritis (PIA) in rats is an animal model for rheumatoid arthritis (RA). We have previously identified seven quantitative trait loci (QTLs), which regulate arthritis development using a cross between the susceptible DA strain and the resistant E3 strain of rats (Pia2-8). In the present study the inbred rat strain LEW.1F was used as the susceptible strain in a cross with the E3 strain. The results confirmed the locus Pia4 on chromosome 12, which previously was shown to be associated with PIA, and also with experimental allergic encephalomyelitis, in crosses between the rat strains E3 and DA. On chromosome 1, linked to the albino locus, we identified a novel QTL, Pia9 in the LEW.F1 cross. This locus was associated with arthritis severity in the early phase of disease. A locus on chromosome 16, denoted Pia11, was also associated with arthritis severity in the early phase of the disease. A suggestive locus was detected on chromosome 14, which was associated with arthritis severity at the time when PIA progresses into a chronic phase. Using a congenic LEW.1F strain, which carries E3 alleles at the Pia9 locus, we confirmed that the E3 allele significantly suppresses arthritis severity during the early phase of the disease. The results revealed synergistic effects between different susceptibility loci using ANOVA analysis. These interactions were influenced by gender. Rats with Pia9 alleles from LEW.1F and Pia11 alleles from E3, were shown to suffer from much more severe arthritis in the early stage of the disease. On the other hand, the Pia9 and the suggestive locus on chromosome 14 affected only males during the chronic phase of the disease. These findings provide clues to how genetic factors by themselves, and in interaction with each other, regulate the development of a disease, which displays many similarities to RA.     

Collagen type II-specific monoclonal antibody-induced arthritis in mice: description of the disease and the influence of age, sex, and genes

Transfer of collagen type II (CII)-specific monoclonal antibodies induces an acute form of arthritis (collagen type II antibody-induced arthritis, CAIA) in na?ve mice. Arthritis was induced using a pair of monoclonal antibodies M2139 and CIIC1, binding to J1 and C1(I) epitopes of CII, respectively. Thereafter, lipopolysaccharide injection was used to increase the incidence and severity of the disease. This model was used to investigate the effect of genes, age, and sex as well as effector cells in the end-stage effector phase of arthritis pathogenesis. Injection of a single monoclonal antibody induced arthritis only after lipopolysaccharide stimulation. CAIA showed differences in disease penetration among the susceptible strains indicating the importance of non-major histocompatibility complex genes on the antibody effector pathway. B-cell-deficient mice were susceptible to CAIA and in some genetic backgrounds B-cell deficiency leads to enhanced arthritis. Histology of the affected paws revealed massive infiltrations of neutrophils along with bone and cartilage erosion, pannus formation, and fibrin deposition. Depletion of neutrophils significantly reduced the incidence and severity of the disease. CAIA susceptibility increased with age. Males were more susceptible than females and estrogen treatment decreased the development of arthritis. We conclude that CAIA is an acute arthritis triggered by antibody binding and neutrophils bypassing immune activation but with many characteristics in common with collagen-induced arthritis.     

The effects of female sex steroids on the development of autoimmune thyroiditis in thymectomized and irradiated rats

Female PVG/c strain rats are more susceptible to the induction of autoimmune thyroiditis initiated by thymectomy and irradiation (Tx-X) than similarly treated males. Pre-pubertal ovariectomy was found to further augment this susceptibility. The administration of oestrogen or progesterone to groups of 4 week old ovariectomized Tx-X animals over a period of 15 weeks significantly altered the course of the events leading to the induction of this condition. Thus oestrogen administered repeatedly at dose levels of 1 microgram and 10 micrograms/100 g body weight resulted in partial suppression of thyroiditis with a corresponding change in the incidence of antibodies to thyroglobulin. Similarly, oestrogen administered by a single implantation had a suppressive effect on the development of autoimmunity in ovariectomized Tx-X females. Oestrogen given by either of these procedures also reduced the incidence of both thyroiditis and autoantibody induction in orchidectomized male Tx-X rats. In contrast to the inhibitory effects of oestrogen, the repeated administration of progesterone at a dose of 250 ng and 1,500 micrograms/100 g body weight appeared to augment the levels of autoimmunity. It is concluded that the differential susceptibility to the induction of autoimmunity by thymectomy and irradiation is the direct consequence of sex hormonal influences. Furthermore, the higher incidence of the disease in the female would appear to be determined by the balance between the activity of oestrogen and progesterone which would further appear to have antagonistic influences in this particular situation.     

Influence of neonatal androgen on the display of territorial marking behavior in the gerbil.

The effect of the presence or absence of androgen during the neonatal period on territorial marking behavior in the Mongolian gerbil was studied. Scent marking frequency was 20-40 fold greater in males than in females. Gonadectomy depressed marking in males but not in females. Testosterone propionate (TP) therapy completely restored marking in male but increased marking in intact and ovariectomized females to only one fourth that in males. Genetic males castrated within 2 days postpartum did not mark more frequently than TP-treated females after TP treatment in adulthood. Genetic females given a single TP injection within 6 days postpartum marked at male levels after TP treatment in adulthood. Males castrated after Day 2 and females given TP after Day 6 displayed marking frequencies intermediate between normal male and female levels after TP treatment in adulthood. This study suggests that sexual dimorphism in territorial marking behavior is due to a sex difference in the competency to respond to androgen, and it appears that development of this competency occurs during the neonatal period and is regulated, at least in part, by androgen. The onset of this differentiation process occurs earlier in the male than in the female.     

Ejaculatory and postejaculatory behavior of male and female rats: effects of sex hormones and electric shock

Ejaculatory patterns were observed in normally reared, postpuberally castrated male and female rats treated with sex hormones and electrical shock in adulthood. In a preliminary experiment, 3 females treated with 50 microgram estradiol benzoate (EB) and 500 microgram progesterone (P) showed intromission and ejaculatory behavior when subjected to shock. Refractory periods were abnormally short and there was almost no postejaculatory vocalization. In Experiment 1, males and females were tested with electrical shock following daily treatment with 32 microgram EB with and without 500 microgram P on the test day. There was no difference between males and females in preejaculatory behavior, but females displayed abbreviated refractory periods and no postejaculatory vocalization. Progesterone had no observed effect. In Experiment 2 castrated males and females were subjected to shock after treatment with 8 microgram EB per day for 3 weeks. No P was given. Again females showed drastically reduced refractory periods and little vocalization. In Experiment 3, males and females treated with TP and shock displayed ejaculatory patterns, normal refractory periods and vocalization. Results show that female rats are capable of exhibiting the ejaculatory response without sex hormone treatment in perinatal life or androgen treatment in adulthood. It was also demonstrated that there is a sex difference in the postejaculatory behavior shown by estrogen-treated male and female rats.     

Oestradiol suppression of delayed-type hypersensitivity in autoimmune (NZB/NZW)F1 mice is a trait inherited from the healthy NZW parental strain.

In this paper we report that treatment with 17 beta-oestradiol depresses cutaneous delayed-type hypersensitivity (DTH) to oxazolone (OXA) in female oophorectomized NZB/W mice. Analysis of the parental strains revealed that this oestrogen-induced inhibition of DTH mice is a trait inherited from the healthy NZW and not from the autoimmune NZB strain. The down-regulating effect of oestradiol on DTH in female NZB/W mice was found both in the sensitization and effector phase of the DTH response. Decreased DTH reactivity to OXA was demonstrated in oophorectomized NZB/W and NZW mice after administration of both low, physiological doses (s.c. injections) and high, pharmacological doses (siliac tube implantation) of oestradiol. In addition, s.c. implantation of testosterone containing siliac tubes suppressed DTH reactivity to OXA in castrated male NZW mice. This down-regulating effect was not found in male NZB or NZB/W mice similarly treated. Serological analysis revealed that high doses of oestradiol increased whereas testosterone depressed the IgG anti-OXA antibody responses in female NZB/W mice. Our results indicate that one possible contribution of the NZW parental strain to the lupus disease in NZB/W mice is a trait of oestrogen sensitivity leading to the acceleration of the autoimmune disease, the latter feature being inherited from NZB mice.     

Oestrogen is a potent disease accelerator in SLE-prone MRL lpr/lpr mice.

The influence of oestrogen on the lupus disease in MRL/l mice has been investigated. Adult, castrated male and female MRL/l mice were administered with s.c. injections of 3.2 micrograms of 17 beta-oestradiol twice a week. The results clearly demonstrate that a relatively small dose of oestrogen is a potent accelerator of the lupus disease in this mouse strain. Thus, administration of oestrogen accelerates glomerulonephritis, lymphoproliferation and mortality. Our results also indicate that oestrogen exerts a dual effect on the immune system of MRL/l mice by depression of antigen-specific and mitogen-induced T cell responses as well as enhancement of polyclonal B cell activation and autoantibody formation. In addition, even short-term administration of oestrogen in the preclinical phase of the disease resulted in long-lasting effects as evaluated by reduced longevity and aggravation of renal disease.     

睾酮干预雄兔膝骨关节炎软骨中胰岛素样生长因子1的表达

背景：睾酮对骨关节炎的作用尚无一致的观点,其调节软骨代谢的作用鲜有文献报道。 目的：观察睾酮对膝骨关节炎雄兔关节软骨中胰岛素样生长因子1表达的影响。 方法：24只雄兔随机分成4组,采用改良Hulth法建立右膝骨关节炎模型;假去势组不切除睾丸,其余3组切除双侧睾丸。第8周末处死假去势组和去势8周组兔取材。第9周开始,激素组肌注生理剂量十一酸睾酮(6 mg/kg, 2周1次),去势16周组正常喂养,并于16周末处死并取材。 结果与结论：大体和组织学观察显示各组兔膝关节软骨的病变程度为假去势组优于去势8周组,激素组优于去势16周组。免疫组化染色显示胰岛素样生长因子1在所有兔膝关节软骨中均有表达,阳性细胞个数假去势组高于去势8周组(P < 0.05),激素组高于去势16周组(P < 0.05),去势8周组与去势16周组差异无显著性意义(P > 0.05)。说明睾酮可通过上调去势雄兔关节软骨中胰岛素样生长因子1的表达,延缓软骨退变。     

Sex differences in body growth in the rat.

Adult male rats are larger than females, due to a persistent difference in the growth rate from puberty onward. Gonadectomy at birth abolished, whereas gonadectomy on Day 21 caused a diminution of the sex differences. There were no differences in growth pattern between females spayed at birth and females spayed on Day 21. In male rats this was different: males castrated at birth became lighter and smaller than males castrated on Day 21. Thus males castrated at birth and females spayed at either age grew at comparable rates which were below the growth rate of males castrated at 21 days. This demonstrated the significant role of the neonatal testes on subsequent growth; prepuberal ovaries did not seem to play an important role. The administration of testosterone propionate (TP) to female rats prenatally suppressed growth of intact, but not of females spayed at birth. This TP effect is ovary-dependent. TP given neonatally promoted growth independently of the ovaries. It is concluded that neonatal androgens organize mechanisms which regulate subsequent body growth in the male rat, and that from puberty on ovarian secretions suppress the growth rate. These opposite actions of the gonads cause the sex differences in body growth of the rat.     

Dose-dependent cardiac effect of oestrogen replacement in mice post-myocardial infarction

Hormonal replacement therapy (HRT) has recently been shown to increase the risk of cardiovascular events in women. However, it is not clear whether the adverse effect of HRT is related to dosage and/or the presence of progestin. Using a mouse model of myocardial infarction (MI), we studied the dose-effect of oestrogen replacement on mortality and cardiac remodelling and dysfunction post-MI in the absence of progestin. Six-week-old females were subjected to ovariectomy (OVX). A pellet containing a low, moderate or high dose of 17beta-oestradiol (E(2); 0.42, 4.2 or 18.8 microg day(-1)) or placebo was implanted subcutaneously on the day of OVX. Myocardial infarction was induced 8 weeks later, and cardiac morphology and function were evaluated 8 weeks after MI. We found that E(2) at moderate and high doses adversely affected mortality. A low dose of E(2) that restored plasma oestrogen close to physiological levels had no significant effect on mortality but tended to improve cardiac function and remodelling, associated with reduced fibrosis and increased capillary density. At the moderate dose, E(2) exacerbated cardiac fibrosis, hypertrophy, dysfunction and dilatation, associated with liver and kidney enlargement and ascites. Protein kinase C and extracellular signal-regulated kinase were increased by MI but were not affected by E(2). In summary, E(2) at a low dose tended to be cardioprotective. At increased doses that raised plasma oestrogen far beyond the physiological level, E(2) was detrimental to the heart. Our data suggest that dosage should be an important consideration when studying the effect of oestrogen replacement on the heart.     

Immunoglobulins from rats that are resistant to adjuvant arthritis suppress the disease in arthritis-susceptible rats

The therapeutic effect of high doses of polyclonal immunoglobulins has been well established in various B cell-associated autoimmune diseases. In the present work we have examined the effect of low doses of immunoglobulins in adjuvant arthritis, a T cell-associated disease in the Lewis rat. Lewis rats were treated with purified rat immunoglobulins as well as their Fc and F(ab′)₂ fragments and their protective effect on adjuvant arthritis was evaluated. We found that early as well as late treatment with low doses of rat immunoglobulins induced refractoriness to disease induction. The effect was found to be carried out by the F(ab′)₂ part of the immunoglobulins and could be adsorbed by affinity purification on Mycobacterium tuberculosis. The protective antibodies were present in Fisher and BN rats that are resistant to adjuvant arthritis, but not in the arthritis susceptible Lewis and Wistar strains. We suggest that resistance to autoimmune arthritis is associated with the presence of protective immunoglobulins and that their effect is carried out through the antigen recognition part of the molecule.     

Gonadectomy and the development of age-dependent polydipsia and the intake of NaCl solutions in the SWR/J mouse.

Gonadectomies were performed at 25 days of life in SWR/J mice, a strain known to develop age-dependent nephrogenic diabetes insipidus with females drinking far more than males. Effect of gonadectomy was different for each of the 3 nonreproductive behaviors studied. (1) Ovariectomy reduced the age-dependent polydipsia seen in females, but castration was without effect in males. (2) Castration of males resulted in a lower intake of an isotonic NaCl solution, making the castrated males similar to the sham-operated and ovariectomized females which did not differ. (3) For the short-term activity measurement sham-operated males did not differ from sham-operated females and castrated males did not differ from ovariectomized females. In each sex, gonadectomy reduced activity.     

Neonatal hormone experience and adult lordosis and fighting in the golden hamster.

Androgenization by testicular secretions or exogenous testosterone propionate (TP treatments administered 24-48 hr post partum) suppressed sexual receptivity in the golden hamster. In response to prolonged adult estradiol benzoate (EB) treatment, gonadectomized normal females and neonatally castrated males exhibited significantly longer total lordosis durations than normal male or neonatally TP-treated (20 mug or 200 mug) females. These results suggest that one aspect of androgen-induced masculinization in the hamster involves reduced estrogen sensitivity. Responses to sequential EB followed by progesterone treatment were also lower in the androgenized groups. Neonatally castrated males did not differ significantly from normal females in their lordosis behavior. Irrespective of adult hormone treatment, androgenized animals fought more than normal females or neonatally castrated males. A genital mask was used to reduce sex differences in peripheral stimulation during testing.