Is there any rationale for prescribing hormone replacement therapy (HRT) to prevent or to treat osteoarthritis?

Using genetic instruments to estimate the causal effect of hormonal reproductive factors on osteoarthritis

Objectives

Hormonal reproductive factors have been considered to play an important role in the etiology of osteoarthritis (OA). We performed Mendelian randomization (MR) to examine whether a causal effect existed between them.

Methods

MR was performed by using publicly released genome-wide association study (GWAS) summary statistics to estimate the causal associations of three relevant exposures, including age at menarche (AAM), age at natural menopause (ANM) and age at first birth (AFB), with the risk of OA. We employed several MR methods, including inverse-variance weighted (IVW), MR-Egger regression, weighted median and weighted mode, to estimate the causality. We performed a sensitivity analysis by manually pruning pleiotropic variants associated with the known confounder body mass index (BMI).

Results

The instrumental variables that achieved genome-wide significance, including 349 AAM single nucleotide polymorphisms (SNPs), 121 AAM SNPs, 54 ANM SNPs, and 10 AFB SNPs, were incorporated into the operation. IVW analysis indicated that each additional year in AFB was associated with a decreasing risk of hip and/or knee OA and overall OA (hip and/or knee OA: OR = 0.79, 95% CI: 0.64-0.93, P = 1.33 × 10^-3; overall OA: OR = 0.80, 95% CI: 0.68-0.92, P = 1.80 × 10^-4). In addition, our results suggested that AAM exerted a causal effect on knee OA in an unfavorable manner (OR = 0.86, 95% CI: 0.76-0.95, P = 1.58 × 10^-3). After accounting for the effect of BMI, the causal effect association between AFB and hip and/or knee OA was also examined (IVW: OR = 0.78, 95% CI: 0.66-0.92, P = 3.22 × 10^-3).

Conclusion

Our findings add a growing body of evidence surrounding the unfavorable effects of early AFB on OA risk, suggesting the essential for relevant health problem management in susceptible populations.

A 12-week randomized, double-blind, placebo-controlled multicenter study of choline-stabilized orthosilicic acid in patients with symptomatic knee osteoarthritis

Background

The aim of this study was to assess the efficacy of choline-stabilized orthosilicic acid (ch-OSA) in patients with symptomatic knee osteoarthritis (OA).

Methods

In a multicenter, double-blind, placebo-controlled study, 211 patients with knee OA (Kellgren and Lawrence grade II or III) and moderate to moderately severe pain were randomly allocated to ch-OSA or placebo for 12 weeks. The primary outcome was the change in the WOMAC pain subscale from baseline to week 12. Secondary outcomes were changes from baseline to week 12 in WOMAC total, WOMAC stiffness, WOMAC physical function, Subject Global Assessment and levels of cartilage degradation biomarkers C-terminal telopeptide of collagen type II (CTX-II) and cartilage oligomeric matrix protein (COMP). Pre-specified subgroup analyses included the effect of gender.

Results

A total of 166 (120 women, 46 men) patients were included in the analysis (87 and 79 in the ch-OSA and placebo group, respectively). In the total study population, no differences were observed between the two treatment groups for the different outcomes but significant treatment x gender interactions were found. In men taking ch-OSA, a significant improvement in WOMAC total, WOMAC stiffness and WOMAC physical function as well as a lower increase in biomarker levels of cartilage degradation was observed, but not in women. The change in WOMAC pain showed a similar positive trend in men taking ch-OSA.

Conclusion

After 12 weeks of treatment, no effect was found of ch-OSA in the total study population on clinical parameters and biomarkers, but a gender interaction was observed. In men, ch-OSA was found effective in reducing symptoms of knee OA, which was associated with a slight but significant reduction of biomarkers that are related to cartilage degradation.

Trial registration

The study was registered retrospectively: ISRCTN88583133. Registration date: 2015-10-07.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1370-7) contains supplementary material, which is available to authorized users.

Vitamin E slows down the progression of osteoarthritis

Osteoarthritis is a chronic degenerative joint disorder with the characteristics of articular cartilage destruction, subchondral bone alterations and synovitis. Clinical signs and symptoms of osteoarthritis include pain, stiffness, restricted motion and crepitus. It is the major cause of joint dysfunction in developed nations and has enormous social and economic consequences. Current treatments focus on symptomatic relief, however, they lack efficacy in controlling the progression of this disease, which is a leading cause of disability. Vitamin E is safe to use and may delay the progression of osteoarthritis by acting on several aspects of the disease. In this review, how vitamin E may promote the maintenance of skeletal muscle and the regulation of nucleic acid metabolism to delay osteoarthritis progression is explored. In addition, how vitamin E may maintain the function of sex organs and the stability of mast cells, thus conferring a greater resistance to the underlying disease process is also discussed. Finally, the protective effect of vitamin E on the subchondral vascular system, which decreases the reactive remodeling in osteoarthritis, is reviewed.

Role of sex hormones in the development of osteoarthritis

Women older than 50 years have a considerably higher prevalence of osteoarthritis than men of the same age group. Although several factors have been proposed, there is some evidence that sex hormones influence the development of osteoarthritis. This article will focus on the basic science and clinical evidence that describe the current state of knowledge regarding the relationship between sex hormones and the development of osteoarthritis.

17β-estradiol reduces expression of MMP-1, -3, and -13 in human primary articular chondrocytes from female patients cultured in a three dimensional alginate system

Clinical observations have suggested a relationship between osteoarthritis and a changed sex-hormone metabolism, especially in menopausal women. This study analyzes the effect of 17β-estradiol on expression of matrix metalloproteinases-1, -3, -13 (MMP-1, -3, -13) and tissue inhibitors of metalloproteinases-1, -2 (TIMP-1, -2) in articular chondrocytes. An imbalance of matrix metalloproteinases (MMPs) specialized on degradation of articular cartilage matrix over the respective inhibitors of these enzymes (TIMPs) that leads to matrix destruction was postulated in the pathogenesis of osteoarthritis. Primary human articular chondrocytes from patients of both genders were cultured in alginate beads at 5% O(2) to which 10(-11)M-10(-5)M 17β-estradiol had been added and analyzed by means of immunohistochemistry, immunocytochemistry and real-time RT-PCR. Since articular chondrocytes in vivo are adapted to a low oxygen tension, culture was performed at 5% O(2). Immunohistochemical staining in articular cartilage tissue from patients and immunocytochemical staining in articular chondrocytes cultured in alginate beads was positive for type II collagen, estrogen receptor α, MMP-1, and -13. It was negative for type I collagen, MMP-3, TIMP-1 and -2. Using real-time RT-PCR, it was demonstrated that physiological and supraphysiological doses of 17β-estradiol suppress mRNA levels of MMP-3 and -13 significantly in articular chondrocytes of female patients. A significant suppressing effect was also seen in MMP-1 mRNA after a high dose of 10(-5)M 17β-estradiol. Furthermore, high doses of this hormone led to tendentially lower TIMP-1 levels whereas the TIMP-2 mRNA level was not influenced. In male patients, only incubations with high doses (10(-5)M) of 17β-estradiol were followed by a tendency to suppressed MMP-1 and TIMP-1 levels while TIMP-2 mRNA level was decreased significantly. There was no effect on MMP-13 expression of cells from male patients. Taken together, application of 17β-estradiol in physiological doses will improve the imbalance between the amounts of MMPs and TIMPs in articular chondrocytes from female patients. Downregulation of TIMP-2 by 17β-estradiol in male patients would not be articular cartilage protective.

Osteoarthritis in Women: Effects of Estrogen, Obesity and Physical Activity

Arthritis is the leading cause of physical disability in the USA and osteoarthritis (OA), the most common form, affects nearly 27 million people. Women have a higher prevalence of OA than men, but the underlying causes for the increased susceptibility of women to OA are not fully understood. This review discusses the associations of sex hormones, obesity and physical activity with the incidence and progression of OA in women. Although many studies have explored the relationships of estrogen and reproductive history with the risk of OA or joint replacement, there is no consensus on the role of these factors. Obesity clearly increases risk for OA, but whether obesity affects women and men differently is uncertain. Moderate levels of physical activity do not appear to increase the incidence or progression of OA and may even have a weak protective effect. Future investigations should focus on sex-specific mechanisms for the development of OA and determine whether there are modifiable factors (e.g., estrogen, obesity, physical activity) that can be targeted through prevention and treatment strategies to mitigate the increased incidence and prevalence of OA in women.

Localization of estrogen receptors alpha and beta in the articular surface of the rat femur

It has been suggested that the degradation of the articular cartilage and osteoarthritis (OA) are associated with gender and the estrogen hormone. Although many investigators have reported the presence of the estrogen receptors (ERs) α and β in the articular cartilage, the localization of these receptors and the difference in their in vivo expression have not yet been clearly demonstrated. We performed immunofluorescence staining of ERα and ERβ to elucidate the localization of the ERs and to note the effects of gender and the aging process on these receptors. The results revealed that ERα and ERβ were expressed in the articular cartilage and subchondral bone layers of adult rats of both sexes. We also observed the high expression of these receptors in immature rats. In contrast, their expression levels decreased in an ovariectomised model, as a simulation of postmenopause, and in aged female rats. Therefore, this study suggests the direct effects of estrogen and ER expression on articular surface metabolism.

Estrogen receptor alpha regulates matrix metalloproteinase-13 promoter activity primarily through the AP-1 transcriptional regulatory site

Many females develop bone diseases such as osteoporosis, and joint diseases such as osteoarthritis after menopause when estrogen levels decline. As estrogen receptors (ER) are present in such tissues, it is possible that the loss of estrogen at menopause influences the expression of enzymes such as members of the MMP family of proteinases to affect bone and connective tissue metabolism. The present study was undertaken to assess a possible relationship between ER-alpha and MMP-13 expression at the promoter level, and to determine how such a relationship could be modulated by ligands such as estrogen. Using a rabbit synovial cell line lacking endogenous ER, a transient transfection system with an ER-alpha construct, and a series of MMP-13 promoter-luciferase constructs of varying lengths and with specific mutations in transcription factor binding sites, it was found that ER-alpha can significantly enhance MMP-13 promoter activity via the AP-1 site, with modulatory influences by the Runx and PEA-3 sites on this ER-alpha dependent enhancement of the promoter activity. This enhancement by ER-alpha was significantly depressed in the presence of 17-ss-estradiol in a dose dependent manner. The influence of tamoxifen and raloxifen on the activity of the ER-alpha was consistent with their known agonist/antagonist activity. These findings indicate that loss of estrogen in vivo could potentially lead to enhanced expression of MMP-13, a proteinase that has been implicated in both osteoporosis and osteoarthritis, and thus contribute to the development and progression of these conditions.

Influence of 17beta-estradiol and insulin on type II collagen and protein synthesis of articular chondrocytes

Clinical observations have suggested a relationship between osteoarthritis and a changed estrogen metabolism in menopausal women. Type II collagen is one main structural protein of articular cartilage matrix and its synthesis is increased by insulin in growth plate cartilage. Therefore, it was investigated if [(3)H]-proline incorporation and type II collagen synthesis (immunocytochemistry, ELISA) in female bovine articular chondrocytes are affected by 17beta-estradiol and/or insulin. Articular chondrocytes were cultured in monolayers at 5% O(2) in medium containing serum for 5-9 days, followed by application of 10(-13) to 10(-9) M estradiol or 5 microg/ml insulin during a serum-free culture phase of 2-3 days. Immunostaining for type II collagen was strong in the serum-free culture phase whereas it was negative for type I collagen, indicating that cells did not dedifferentiate to fibroblast-like cells during culture in serum-free medium. Whereas insulin raised the proline incorporation and the type II collagen synthesis significantly, physiological doses of estradiol did not show significant effects. The stimulating effect of insulin on the [(3)H]-proline incorporation or the type II collagen synthesis was significantly suppressed after preincubation of cells with 10(-11) to 10(-9) M estradiol resembling an unfavorable effect for articular cartilage. The suppression was reversed if cells were incubated with 10(-11) to 10(-7) M tamoxifen or ICI 182,780 combined with 10(-11) or 10(-9) M estradiol followed by incubation with 5 microg/ml insulin, indicating an estrogen receptor-mediated process. Because the articular cartilage of diabetic patients is biomechanically less stable, further experiments are needed to clarify the role of estradiol and insulin in the metabolism of articular chondrocytes.

Extracellular matrix changes in knee joint cartilage following bone-active drug treatment

Certain drugs or treatments that are known to affect bone quality or integrity might have side effects on the extracellular matrix of articular cartilage. We investigated the effects of vitamin D and calcium deficiency, estrogen deficiency, and hypercortisolism alone or in combination with bisphosphonates or sodium fluoride in an animal model, viz., the Göttingen miniature pig (n=29). The articular cartilage from knee joints was analyzed for its content of glycosaminoglycans (GAGs, as macromolecules responsible for the elasticity of articular cartilage) by a spectrometric method with dimethylene blue chloride. In cryo- or paraffin sections, alkaline phosphatase (AP, as an enzyme indicating mineralization or reorganization of articular cartilage matrix) was localized by enzyme histochemistry, and positive cells were counted, whereas differently sulfated GAGs were stained histochemically. A significant decrease in GAG content was measured in ovariectomized and long-term glucocorticoid-treated animals compared with untreated animals. In the glucocorticoid/sodium fluoride group, GAGs were significantly diminished, and significantly fewer AP-positive chondrocytes were counted compared with the control. GAG content was slightly higher, and significantly more AP-positive chondrocytes were counted in short-term glucocorticoid-treated animals then in the control group. GAGs, as part of proteoglycans, are responsible for the water-storage capacity that gives articular cartilage its unique property of elasticity. Thus, ovariectomy and long-term glucocorticoid therapy, especially when combined with sodium fluoride, have detrimental effects on this tissue.

Human articular chondrocytes exhibit sexual dimorphism in their responses to 17beta-estradiol

OBJECTIVE

The higher incidence of osteoarthritis in females suggests that there may be intrinsic sex-specific differences in human articular chondrocytes. 17beta-Estradiol (E2) regulates rat growth plate chondrocytes through traditional nuclear receptor mechanisms, but only female cells exhibit rapid membrane-associated effects mediated through protein kinase C (PKC) alpha. Here we demonstrate sexual dimorphism in the physiological response of human articular chondrocytes to E2.

METHODS

Articular chondrocytes were obtained at the time of autopsy from three male and three female donors between 16 and 39 years of age. Second passage cultures were treated with E2 for 24 h to assess the effects of the hormone on [3H]-thymidine incorporation, [35S]-sulfate incorporation, and alkaline phosphatase specific activity. In addition, the chondrocytes were treated for 3, 9, 90 or 270 min and PKC specific activity was determined.

RESULTS

All chondrocytes were positive for aggrecan and estrogen receptor alpha mRNAs but were negative for type II collagen mRNA. Only cells from female donors responded to E2. DNA synthesis, sulfate incorporation and alkaline phosphatase activity were increased. E2 caused a rapid increase in PKC activity in the female cells within 9 min that was maximal at 90 min. Treatment with the PKC inhibitor chelerythrine blocked these effects.

CONCLUSIONS

These results provide the first definitive evidence that normal human cells exhibit an intrinsic sex-specific response to E2 and suggest that sexual dimorphism may be an important variable in assessing the pathways that modulate cell behavior.

Glucosamine sulfate reduces osteoarthritis progression in postmenopausal women with knee osteoarthritis: evidence from two 3-year studies

OBJECTIVE

To investigate the effect of glucosamine sulfate on long-term symptoms and structure progression in postmenopausal women with knee osteoarthritis (OA).

DESIGN

This study consisted of a preplanned combination of two three-year, randomized, placebo-controlled, prospective, independent studies evaluating the effect of glucosamine sulfate on symptoms and structure modification in OA and post-hoc analysis of the results obtained in postmenopausal women with knee OA. Minimal joint space width was assessed at baseline and after 3 years from standing anteroposterior knee radiographs. Symptoms were scored by the algo-functional WOMAC index at baseline and after 3 years. All primary statistical analyses were performed in intention-to-treat, comparing joint space width and WOMAC changes between groups by ANOVA.

RESULTS

Of 414 participants randomized in the two studies, 319 were postmenopausal women. At baseline, glucosamine sulfate and placebo groups were comparable for demographic and disease characteristics, both in the general population and in the postmenopausal women subset. After 3 years, postmenopausal participants in the glucosamine sulfate group showed no joint space narrowing [joint space change of +0.003 mm (95% CI, -0.09 to 0.11)], whereas participants in the placebo group experienced a narrowing of -0.33 mm (95% CI, -0.44 to -0.22; P < 0.0001 between the two groups). Percent changes after 3 years in the WOMAC index showed an improvement in the glucosamine sulfate group [-14.1% (95%, -22.2 to -5.9)] and a trend for worsening in the placebo group (5.4% (95% CI, -4.9 to 15.7) (P = 0.003 between the two groups).

CONCLUSION

This analysis, focusing on a large cohort of postmenopausal women, demonstrated for the first time that a pharmacological intervention for OA has a disease-modifying effect in this particular population, the most frequently affected by knee OA.