Pregnancy loss, menopause, and the onset of rheumatoid arthritis

Reproductive history and postmenopausal rheumatoid arthritis among women 60 years or older: Third National Health and Nutrition Examination Survey

OBJECTIVE

Rheumatoid arthritis, a condition of unknown etiology, has been associated with considerable costs to society. The purpose of this study is to determine whether selected reproductive history characteristics are associated with postmenopausal rheumatoid arthritis diagnosis.

METHODS

Secondary analyses were performed using cross-sectional data from the Third National Health and Nutrition Examination Survey. Of 1,892 eligible participants, 182 fulfilled the criteria for postmenopausal rheumatoid arthritis, based on self-report and the 1987 American College of Rheumatology criteria. Logistic regression models were constructed, and odds ratios (ORs) with their 95% CIs were calculated for selected reproductive history characteristics as predictors of postmenopausal rheumatoid arthritis, after adjustment for potential confounders.

RESULTS

Multivariate logistic models suggested that age at menopause was the only reproductive characteristic that was significantly associated with the outcome of interest (OR, 0.96; 95% CI, 0.93-0.99). Compared with women experiencing menopause at 50 years of age or later, those who experienced menopause before 40 years of age (OR, 2.53; 95% CI, 1.41-4.53) had increased odds of postmenopausal rheumatoid arthritis.

CONCLUSIONS

Women who experience menopause before 40 years of age seem to be at increased risk for postmenopausal rheumatoid arthritis. Conversely, age at menarche and pregnancy history may not predict rheumatoid arthritis after menopause. Further research is needed to confirm and elucidate these epidemiological findings.

17beta-Estradiol utilizes the estrogen receptor to regulate CD16 expression in monocytes

Estrogen can significantly influence CD16 expression and alter monocytic cytokine release upon CD16 receptor activation. However, the function of the estrogen receptor (ER) alpha and beta in this response is unclear. To test whether estrogen binds ERalpha and/or ERbeta to affect CD16 expression, monocytic cells were treated with and without physiological levels of 17beta-estradiol and various doses of the ERalpha and ERbeta antagonist fulvestrant followed by measurement of CD16 transcript levels. To determine how estrogen induced changes in TNF-alpha and IL-1beta release due to CD16 activation we quantitated the amount of cytokines after treatment with estrogen, fulvestrant and antibodies that specifically bind and activate the CD16 receptor. Interaction of ERalpha and the CD16 promoter was then determined by chromatin immunoprecipitation. Furthermore, specific promoter elements utilized by estrogen to control CD16 expression were mutated and expression from a luciferase reporter quantitated after transfection. Using the luciferase reporter construct containing a wild type CD16 promoter, the role of ERalpha and ERbeta in the estrogen response was tested by treating transfected monocytes with an ERalpha specific agonist or an ERbeta specific agonist and measuring expression. Our results show that CD16 transcript levels significantly decreased in monocytic cells due to estrogen and that the observed decrease in message was blocked by the antagonist fulvestrant. Estrogen reduced CD16 expression and decreased TNF-alpha and IL-1beta release upon CD16 activation but the administration of fulvestrant blocked this decrease. ERalpha was found to interact with a region 5' of the CD16 gene in the presence of estrogen, and site-directed mutational analysis of this region indicated the necessity for an estrogen response element in modulating estrogen effects on CD16 expression. Moreover, both an ERalpha and an ERbeta agonist reduced expression of the CD16 reporter construct suggesting both receptors can play a role in CD16 regulation. In conclusion, CD16 expression can be altered by the activity of ERalpha or ERbeta and our results also show that ERalpha can associate with a region within the CD16 promoter that is important in production of transcript.

17 beta-estradiol regulates cytokine release through modulation of CD16 expression in monocytes and monocyte-derived macrophages

OBJECTIVE

Macrophages release cytokines, such as tumor necrosis factor alpha (TNF alpha), interleukin-1 (IL-1), and IL-6, which modulate the symptoms of rheumatoid arthritis (RA). Macrophage release of these cytokines can be modulated by estrogen. Fc gamma receptor type IIIA (CD16a) is a receptor expressed on macrophages that selectively binds IgG molecules, an important rheumatoid factor in RA. Binding of CD16 by anti-CD16 monoclonal antibodies stimulates macrophage cytokine release. We undertook this study to test the hypothesis that decreased concentrations of estrogen (17 beta-estradiol) directly cause an increase in CD16 expression, resulting in increased release of proinflammatory cytokines from monocytes and/or macrophages upon receptor binding.

METHODS

THP-1 cells and female human primary monocytes and monocyte-derived macrophages were treated with no 17 beta-estradiol, physiologic levels (1 x 10(-8)M) of 17 beta-estradiol, or 1 x 10(-8)M 17 beta-estradiol followed by withdrawal of 17 beta-estradiol. Surface expression of CD16 and CD16 messenger RNA was measured using fluorescence-activated cell sorting (FACS) and semiquantitative reverse transcription-polymerase chain reaction, respectively. Cytokine release from 17 beta-estradiol-treated or untreated monocytes was then quantitated by enzyme-linked immunosorbent assay and FACS after crosslinking the receptor with anti-CD16 antibodies.

RESULTS

CD16 transcript significantly increased in macrophage-like THP-1 cells and in primary, peripheral blood macrophages in the absence of 17 beta-estradiol, and the observed increase in message was dependent on transcription. CD16 receptor levels on CD14+, transforming growth factor beta-treated primary monocytes also increased in cells deprived of 17 beta-estradiol. Analysis of the cytokines released showed that CD16 crosslinking stimulated significant increases in TNF alpha, IL-1 beta, and IL-6 due to the absence of estrogen.

CONCLUSION

Estrogen can modulate proinflammatory cytokine release from activated monocytes and/or macrophages, in part through modulation of CD16 expression.