Estrone/17β-estradiol conversion to, and tumor necrosis factor inhibition by, estrogen metabolites in synovial cells of patients with rheumatoid arthritis and patients with osteoarthritis

The potential causal association between systemic lupus erythematosus and endocrine and metabolic disorders in the East Asian population: A bidirectional two-sample Mendelian randomization study

OBJECTIVES

Observational studies indicate a significant correlation between systemic lupus erythematosus (SLE) and endocrine and metabolic disorders, but the causal association between SLE and endocrine and metabolic disorders remains unclear due to the reverse causality and confounding biases commonly presented in conventional observational research. This study endeavors to uncover the causal association between SLE and three common endocrine and metabolic disorders, including Graves' disease (GD), type 2 diabetes mellitus (T2DM), and osteoporosis (OP).

METHODS

We used genome-wide association study data for SLE and three endocrine and metabolic disorders in an East Asian population, employing bidirectional two-sample Mendelian randomization (MR) analysis and sensitivity analysis to ascertain the causal association between SLE and endocrine and metabolic disorders.

RESULTS

A multiplicative random-effect inverse-variance weighted approach revealed a significant positive correlation between SLE and an elevated risk of GD with an odds ratio (OR) of 1.12 (95% CI: 1.04-1.22, p < .01), and inverse-variance weighted (IVW) analysis also indicated that SLE increased the risk of OP with an OR of 1.035 (95% CI: 1.003-1.068, p < .05). Additionally, GD causally affected SLE in an IVW analysis after Bonferroni correction, with an OR of 1.33 (95% CI: 1.19-1.49, p < .05/3), but the application of multivariable MR analysis resulted in the absence of a causal association of GD on SLE (OR 1.047, 95% CI: 0.952-1.151, p > .05). Lastly, the robustness and validity of the findings were verified through a sensitivity analysis.

CONCLUSIONS

We confirmed that SLE has a causal effect on GD as well as OP, but no evidence exists to substantiate a causal link between SLE and T2DM. Our study offers valuable contributions for uncovering the etiology of SLE and endocrine and metabolic disorders and furthering disease risk research while providing potential targets for disease monitoring and therapeutic intervention.

Differential inflammation-mediated function of prokineticin 2 in the synovial fibroblasts of patients with rheumatoid arthritis compared with osteoarthritis

Prokineticin 2 (PK2) is a secreted protein involved in several pathological and physiological processes, including the regulation of inflammation, sickness behaviors, and circadian rhythms. Recently, it was reported that PK2 is associated with the pathogenesis of collagen-induced arthritis in mice. However, the role of PK2 in the pathogenesis of rheumatoid arthritis (RA) or osteoarthritis (OA) remains unknown. In this study, we collected synovial tissue, plasma, synovial fluid, and synovial fibroblasts (SF) from RA and OA patients to analyze the function of PK2 using immunohistochemistry, enzyme-linked immunosorbent assays, and tissue superfusion studies. PK2 and its receptors prokineticin receptor (PKR) 1 and 2 were expressed in RA and OA synovial tissues. PKR1 expression was downregulated in RA synovial tissue compared with OA synovial tissue. The PK2 concentration was higher in RA synovial fluid than in OA synovial fluid but similar between RA and OA plasma. PK2 suppressed the production of IL-6 from TNFα-prestimulated OA-SF, and this effect was attenuated in TNFα-prestimulated RA-SF. This phenomenon was accompanied by the upregulation of PKR1 in OA-SF. This study provides a new model to explain some aspects underlying the chronicity of inflammation in RA.

Estrogen receptor Alpha in human knee articular cartilage of healthy and osteoarthritic females

Objective

Estrogen and osteoarthritis association has previously been proposed. This study evaluates the presence of estrogen receptors (ER)-α in articular cartilage, and its association.

Methods

A prospective cohort study of women undergoing anterior cruciate ligament reconstruction (controls) or total knee arthroplasty (cases) was performed. Cartilage samples were processed and ER-α expression was quantified.

Results

Twenty patients were included: 12 cases and 8 controls. ER-α expression was higher in the case subjects.

Conclusion

Increased ER-α expression is associated with age, and degeneration. This suggests estrogen deficiency is a risk for osteoarthritis and is inversely related to proliferative looking chondrocytes.

Wechselwirkungen zwischen neuroendokrinem System und Immunsystem bei chronisch-entzündlichen Systemerkrankungen

Hormonelle und neuronale Signalwege können die Manifestation einer chronisch-entzündlichen Systemerkrankung entweder begünstigen oder verhindern. Bei bereits manifester Erkrankung modulieren Hormone und Neurotransmitter den Krankheitsverlauf, in dem sie die Krankheitsaktivität erhöhen oder abschwächen. Beispiele hierfür sind der entzündungshemmende Einfluss der körpereigenen und exogenen Glukokortikoide und die entzündungsfördernden Effekte von Stress bei chronisch-entzündlichen Systemerkrankungen. Bei chronisch-entzündlichen Systemerkrankungen ringt das aktivierte Immunsystem mit dem Gehirn und anderen Organsystemen um Energie, was zu vielfältigen Erkrankungsfolgen und Folgeerkrankungen führt: „sickness behaviour“ mit Fatigue-Symptomatik und depressiven Symptomen, Schlafstörungen, Anorexie, Fehl- und Mangelernährung, Knochenabbau, Muskelabbau und kachektische Fettsucht, Insulinresistenz mit Hyperinsulinämie (begleitet von einer Resistenz gegenüber dem Insulin-like growth factor 1), Dyslipidämie, Veränderungen der Steroidhormonachsen, Störungen der Hypothalamus-Hypophysen-Gonaden-Achse, erhöhter Sympathikotonus, herabgesetzte Aktivität des parasympathischen Nervensystems, arterielle Hypertonie und Volumenbelastung, Entzündungsanämie und zirkadiane Rhythmik der Symptomausprägung. Diese für die Patienten gravierenden Folgeerkrankungen, welche den chronisch-entzündlichen Systemerkrankungen inhärent sind, sollten konsequent therapiert werden.

Interactions of neuroimmune signaling and glutamate plasticity in addiction

Chronic use of drugs of abuse affects neuroimmune signaling; however, there are still many open questions regarding the interactions between neuroimmune mechanisms and substance use disorders (SUDs). Further, chronic use of drugs of abuse can induce glutamatergic changes in the brain, but the relationship between the glutamate system and neuroimmune signaling in addiction is not well understood. Therefore, the purpose of this review is to bring into focus the role of neuroimmune signaling and its interactions with the glutamate system following chronic drug use, and how this may guide pharmacotherapeutic treatment strategies for SUDs. In this review, we first describe neuroimmune mechanisms that may be linked to aberrant glutamate signaling in addiction. We focus specifically on the nuclear factor-kappa B (NF-κB) pathway, a potentially important neuroimmune mechanism that may be a key player in driving drug-seeking behavior. We highlight the importance of astroglial-microglial crosstalk, and how this interacts with known glutamatergic dysregulations in addiction. Then, we describe the importance of studying non-neuronal cells with unprecedented precision because understanding structure-function relationships in these cells is critical in understanding their role in addiction neurobiology. Here we propose a working model of neuroimmune-glutamate interactions that underlie drug use motivation, which we argue may aid strategies for small molecule drug development to treat substance use disorders. Together, the synthesis of this review shows that interactions between glutamate and neuroimmune signaling may play an important and understudied role in addiction processes and may be critical in developing more efficacious pharmacotherapies to treat SUDs.

Incidental findings of temporomandibular joint osteoarthritis and its variability based on age and sex

Purpose

This study investigated the prevalence of temporomandibular joint osteoarthritis (TMJ-OA) using the Research Diagnostic Criteria for Temporomandibular Disorders image analysis criteria, assessed the severity of incidental osteoarthritic changes affecting the TMJ, and evaluated the correlations of sex and age with the prevalence and severity of TMJ-OA.

Materials and Methods

This retrospective study assessed 145 randomly selected cone-beam computed tomography scans (261 TMJs) from the authors' institutional maxillofacial radiology archive following the application of inclusion and exclusion criteria. The criteria described by Ahmad et al. were used to determine whether each TMJ was affected by OA, and the severity of the osteoarthritic changes was scored for each joint based on the method described by Alexiou et al. The chi-square, McNemar, Bhapkar chi-square, and Stuart-Maxwell chi-square tests were applied to evaluate the significance of the relationships between variables (age and sex).

Results

Sixteen TMJs (6.1%) had no OA, 74 (28.6%) were indeterminate for OA, and 171 (65.5%) had OA. Flattening and sclerosis were observed in 86.6% and 12.3% of cases, respectively, while resorption was observed in 7.3% of the joints. Only 21 (8.1%) of the examined TMJs had subchondral cysts. Erosion of the articular eminence was observed in 58 (22.1%) cases, while sclerosis and resorption were found in 68 (25.9%) and 16 (6.1%) TMJs, respectively.

Conclusion

Female patients had a higher prevalence and severity of TMJ-OA than male patients. The prevalence and severity of TMJ-OA increased with age, with peaks in the fifth and seventh decades of life.

High susceptibility to collagen-induced arthritis in mice with progesterone receptors selectively inhibited in osteoprogenitor cells

Background

Progesterone receptor (PR) affects immunomodulation, and lack of PR in osteoprogenitor cells primarily affects pathways associated with immunomodulation, especially in males. In this study, we selectively deleted PR from osteoprogenitor cells using Prx1-Cre to evaluate the tissue-specific effects of PR on the pathegenesis of inflammatary arthritis (IA).

Methods

Collagen-induced arthritis (CIA) was used as an IA animal model. Both male and female PR^ΔPrx1 mice and their wild-type (WT) littermates were immunized with collagen II (CII) emulsified complete Freund’s adjuvant (CFA). Joint erosion, inflammation, and cartilage damage were assessed using a semiquantitative histologic scoring system. Bone volume and erosions in knee and ankle joints were quantitated using microCT and histology.

Results

Bone erosions developed in both paw joints in 37.5% and 41.7% of the WT and PR^ΔPrx1 female mice and in 45.4 and 83.3% of the WT and PR^ΔPrx1 male mice, respectively. Also, both joint damage and subchondral bone erosions were significantly more severe in male PRcKO-CIA mice than in male WT-CIA mice. Female PR^ΔPrx1 mice also developed higher bone loss in the knee joints than the KO-normal or WT-CIA females although with less severity compared to the male mice.

Conclusions

The presence of PR in osteoprogenitor cells decreased the development of collagen-induced arthritis and might help to explain the sex differences observed in human inflammatory arthritis.

Metabolic linkages between indoor negative air ions, particulate matter and cardiorespiratory function: A randomized, double-blind crossover study among children

BACKGROUND

Ionization air purifiers, which purify particulate matter (PM) by producing vast number of negative air ions (NAI), are widely used. Recent study implied that ionization air purification could bring respiratory benefits but deterioration of heart rate variability (HRV). However, its underlying molecular mechanisms remain unclear.

OBJECTIVES

To explore the molecular linkages between indoor NAI, decreased PM and the cardiorespiratory effect after purification.

METHODS

Urine samples were collected from 44 healthy children three times of each study period (real and sham purification) in an existing randomized, double-blind crossover study. Ultra-high performance liquid chromatography/mass spectrometry was conducted in metabolomics analysis, the associations between indoor NAI, decreased PM and the cardiorespiratory function were investigated via the meet-in-metabolite approach (MIMA) based on statistical and metabolic pathway analysis. Mixed-effect models were used to establish associations between exposure, health parameters and metabolites.

RESULTS

Twenty-eight and fourteen metabolites were identified with significant correlations to NAI and PM, respectively. Besides, eight and eighteen metabolites were separately associated with respiratory function and HRV. The increased NAI and decreased PM improved respiratory function mainly with eight pathways, promoting energy production, anti-inflammation and anti-oxidation capacity. Decreased PM ameliorated HRV with six main pathways, increasing energy production and anti-inflammation capacity while increased NAI deteriorated HRV with five main pathways, lowering energy generation and anti-oxidation capacity.

CONCLUSIONS

Increased NAI and decreased PM ameliorated respiratory function by increasing energy production, improving anti-inflammation and anti-oxidation capacity. Decreased PM improved cardiac autonomic function by increasing energy production and anti-inflammation capacity, while these benefits were overcast by massive NAI via lowering energy generation and anti-oxidation capacity with different metabolic pathways.

A thyroid hormone network exists in synovial fibroblasts of rheumatoid arthritis and osteoarthritis patients

While patients with rheumatoid arthritis (RA) sometimes demonstrate thyroidal illness, the role of thyroid hormones in inflamed synovial tissue is unknown. This is relevant because thyroid hormones stimulate immunity, and local cells can regulate thyroid hormone levels by deiodinases (DIO). The study followed the hypothesis that elements of a thyroid hormone network exist in synovial tissue. In 12 patients with RA and 32 with osteoarthritis (OA), we used serum, synovial fluid, synovial tissue, and synovial fibroblasts (SF) in order to characterize the local thyroid hormone network using ELISAs, immunohistochemistry, imaging methods, tissue superfusion studies, cell-based ELISAs, flow cytometry, and whole genome expression profiling. Serum/synovial fluid thyroid hormone levels were similar in RA and OA (inclusion criteria: no thyroidal illness). The degradation product termed reverse triiodothyronine (reverse T3) was much lower in serum compared to synovial fluid indicating biodegradation of thyroid hormones in the synovial environment. Superfusion experiments with synovial tissue also demonstrated biodegradation, particularly in RA. Cellular membrane transporters of thyroid hormones, DIOs, and thyroid hormone receptors were present in tissue and SF. Density of cells positive for degrading DIOs were higher in RA than OA. TNF increased protein expression of degrading DIOs in RASF and OASF. Gene expression studies of RASF revealed insignificant gene regulation by bioactive T3. RA and OA synovial tissue/SF show a local thyroid hormone network. Thyroid hormones undergo strong biodegradation in synovium. While bioactive T3 does not influence SF gene expression, SF seem to have a relay function for thyroid hormones.

Estradiol levels are elevated in older men with diffuse cutaneous SSc and are associated with decreased survival

BACKGROUND

Systemic sclerosis (SSc) is a female-predominant disease, characterized by excessive extracellular matrix deposition (ECM) with dermal and internal organ fibrosis. Considering the sex-based disparity in disease incidence, estradiol (E2), an estrogen form with pro-fibrotic effects, may play a role in SSc. We reported that post-menopausal women with diffuse cutaneous (dc)SSc have higher serum E2 levels compared to similar aged, healthy controls. Since males with SSc tend to have more severe disease, we examined serum E2 in dcSSc males in relation to disease characteristics and survival.

METHODS

We measured serum E2 in 83 dcSSc men > 50 years old from the University of Pittsburgh Scleroderma Center and similar aged healthy controls. Using statistical modeling, we examined the associations between serum E2, internal organ involvement, autoantibody profiles, and survival.

RESULTS

Male dcSSc patients had significantly higher serum E2 levels compared to healthy males and similar aged dcSSc post-menopausal women. Male dcSSc patients with high serum E2 had significantly more heart involvement, a trend for higher skin thickness progression rate, and worse survival. Using Cox regression modeling, increased serum E2 levels in anti-Scl-70 antibody-positive dcSSc males were associated with an increased risk of death.

CONCLUSIONS

dcSSc males > 50 years old have higher levels of serum E2 compared to healthy controls and dcSSc post-menopausal women. Elevated serum E2 levels in dcSSc males are associated with heart involvement, trend to progression of dermal fibrosis, and, if anti-Scl-70 antibody positive, worse survival. Our study expands on previous work implicating E2 in dermal fibrosis in SSc and associates E2 levels with internal organ involvement and survival. These data suggest a role for estrogen imbalance in dcSSc.

A phase II study evaluating the efficacy of zoledronic acid in prevention of aromatase inhibitor-associated musculoskeletal symptoms: the ZAP trial

PURPOSE

Aromatase inhibitor-associated musculoskeletal symptoms (AIMSS) are common adverse events of AIs often leading to drug discontinuation. We initiated a prospective clinical trial to evaluate whether bisphosphonates are associated with reduced incidence of AIMSS.

METHODS

In the single-arm trial, the Zoledronic Acid Prophylaxis (ZAP) trial, we compared the incidence of AIMSS against historical controls from the Exemestane and Letrozole Pharmacogenomics (ELPh) trial. Eligible women were postmenopausal with stage 0-III breast cancer planning to receive adjuvant AIs. AIMSS was assessed using the Health Assessment Questionnaire and Visual Analog Scale over 12 months in both trials. Participants in the ZAP trial received zoledronic acid prior to initiating letrozole and after 6 months; ELPh participants included in the analysis were taking letrozole but not bisphosphonates. We analyzed patient-reported outcomes (PROs) and bone density in the ZAP trial using mixed-effects linear regression models and paired t tests, respectively.

RESULTS

From 2011 to 2013, 59 postmenopausal women enrolled in ZAP trial. All 59 (100%) women received baseline and 52 (88%) received 6-month zoledronic acid, and had similar characteristics to historical controls from the ELPh trial (n = 206). Cumulatively during the first year of AI, 37 and 67% of ZAP and ELPh participants reported AIMSS (p < 0.001), respectively. Within the ZAP trial, we did not observe significant changes in other PROs; however, we report improvements in bone mineral density.

CONCLUSIONS

Compared to historical controls, zoledronic acid administered concomitantly with adjuvant AIs was associated with a reduced incidence of AIMSS. A randomized controlled trial is required to confirm these findings.

Detection of 16α-Hydroxyestrone-histone 1 Adduct as High-Affinity Antigen for Rheumatoid Arthritis Autoantibodies

Increased concentrations of 16α-hydroxyestrone (16α-OHE₁) have been observed in rheumatoid arthritis (RA), but the underlying mechanism of this remains elusive. Here we aimed to identify the role played by 16α-OHE₁ in RA. In 40 RA patients, the specificities of antibodies from the sera of these patients were checked by direct binding, inhibition ELISA, and quantitative precipitation titration. Competition ELISA was also used for the estimation of 16α-OHE₁ in the serum of different RA patients. RA IgG from a patient's sera showed strong recognition to 16α-OHE₁-H₁ (histone 1) adduct in comparison to control subjects (p < 0.001), as the formation of this adduct brings out various biochemical changes that might generate neo-epitopes, which have been well-recognized by these antibodies. The affinity of RA antibodies for 16α-OHE₁-H₁ (1.10 × 10^- 7 M) was high, as detected by the Langmuir plot. Comparing RA patients to the controls, no significant differences were detected in the level of 16α-OHE₁ or 2-hydroxyestrone/16α-OHE₁ ratio. 16α-OHE₁-H₁ might have an antigenic role and function as a high-affinity antigen for RA autoantibodies and, therefore, could be used as a biomarker for this disease.

An intracrine view of sex steroids, immunity, and metabolic regulation

Background

Over the past two decades, parallel recognition has grown of the importance of both sex steroids and immune activity in metabolic regulation. More recently, these discrete areas have been integrated in studies examining the metabolic effects of sex steroid immunomodulation. Implicit in these studies has been a traditional, endocrine model of sex steroid delivery from the gonads to target cells, including immune cells. Thus, research to date has focused on the metabolic effects of sex steroid receptor signaling in immune cells. This endocrine model, however, overlooks the extensive capacity of immune cells to generate and metabolize sex steroids, enabling the production of sex steroids for intracrine signaling – that is, sex steroid production for signaling within the cell of origin. Intracrine function allows highly cell-autonomous regulation of sex steroid exposure, and sex steroid secretion by immune cells could confer paracrine signaling effects in neighboring cells within metabolic tissues. In this review, immune cell intracrinology will denote sex steroid production within immune cells for either intracrine or paracrine signaling. This intracrine capacity of immune cells has been well established, and prior work has supported its importance in autoimmune disorders, trauma, and cancer. The potential relevance of immune cell intracrine function to the regulation of energy balance, body weight, body composition, and insulin sensitivity has yet to be explored.

Scope of review

The following review will detail findings to date regarding the steroidogenic and steroid metabolizing capacity of immune cells, the regulation of immune cell intracrine function, and the biological effects of immune-derived sex steroids, including the clinical relevance of immune cell intracrinology in fields other than metabolism. These findings will serve as the basis for a proposed model of immune cell intracrinology constituting a new frontier in metabolism research.

Major conclusions

The development of highly sensitive mass spectrometric methods for sex steroid measurement and quantitation of metabolic flux now allows unprecedented ability to interrogate sex steroid production, metabolism and secretion by immune cells. Immune cell intracrinology could reveal key mechanisms underlying immune cell-mediated metabolic regulation.

•

Sex steroids exert immunomodulatory effects that may influence metabolic health.

•

Immune cells can synthesize, modify, and metabolize sex steroids.

•

Immune cell-derived sex steroids may play intracrine, autocrine, paracrine, and possibly even endocrine roles.

•

Immune cell steroidogenesis is a largely unexplored area of metabolism research.

Stress differentially affects the systemic and leukocyte estrogen network in common carp

Both systemic and locally released steroid hormones, such as cortisol and estrogens, show immunomodulatory actions. This research gives evidence that circulating and leukocyte-derived estrogens can be involved in the regulation of the immune response in common carp, during homeostasis and upon restraining stress. It was found that stress reduced level of blood 17β-estradiol (E2) and down-regulated the gene expression of components of the "classical" estrogen system: the nuclear estrogen receptors and the aromatase CYP19, in the hypothalamus, the pituitary and in the ovaries. In contrast, higher gene expression of the nuclear estrogen receptors and cyp19a was found in the head kidney of stressed animals. Moreover, stress induced changes in the E2 level and in the estrogen sensitivity at local/leukocyte level. For the first time in fish, we showed the presence of physiologically relevant amounts of E2 and the substrates for its conversion (estrone - E1 and testosterone - T) in head kidney monocytes/macrophages and found that its production is modulated upon stress. Moreover, stress reduced the sensitivity of leukocytes towards estrogens, by down-regulation the expression of the erb and cyp19 genes in carp phagocytes. In contrast, era expression was up-regulated in the head kidney monocytes/macrophages and in PBLs derived from stressed animals. We hypothesize that, the increased expression of ERα, that was observed during stress, can be important for the regulation of leukocyte differentiation, maturation and migration. In conclusion, these results indicate that, in fish, the estrogen network can be actively involved in the regulation of the systemic and local stress response and the immune response.

Mixing omics: combining genetics and metabolomics to study rheumatic diseases

Metabolomics is an exciting field in systems biology that provides a direct readout of the biochemical activities taking place within an individual at a particular point in time. Metabolite levels are influenced by many factors, including disease status, environment, medications, diet and, importantly, genetics. Thanks to their dynamic nature, metabolites are useful for diagnosis and prognosis, as well as for predicting and monitoring the efficacy of treatments. At the same time, the strong links between an individual's metabolic and genetic profiles enable the investigation of pathways that underlie changes in metabolite levels. Thus, for the field of metabolomics to yield its full potential, researchers need to take into account the genetic factors underlying the production of metabolites, and the potential role of these metabolites in disease processes. In this Review, the methodological aspects related to metabolomic profiling and any potential links between metabolomics and the genetics of some of the most common rheumatic diseases are described. Links between metabolomics, genetics and emerging fields such as the gut microbiome and proteomics are also discussed.

Autophagy-related IRGM genes confer susceptibility to ankylosing spondylitis in a Chinese female population: a case-control study

It is known that ankylosing spondylitis (AS) and inflammatory bowel disease (IBD) shared a common genetic component. The gist of current study is to assess the role of IBD-associated autophagy gene IRGM on AS susceptibility in a Chinese Han population. A total of 1270 unrelated subjects (643 AS and 627 controls) were enrolled. Two tag single-nucleotide polymorphisms (SNPs) (rs10065172 and rs4958846) were selected and were genotyped by iMLDR Assay technology. Genotypes and haplotype analysis were conducted by using SPSS 16.0 and haploview 4.2 software. Among two tag SNPs of IRGM, no correlation was observed between rs10065172 and AS susceptibility. For rs4958846, genotype and allelic frequencies were marginally discrepant between female cases and controls before, not after, Bonferroni correction (P=0.049; P=0.031). Logistic regression analysis revealed that carriers with CT+TT or CT genotype had a significantly decreased risk for developing AS among female subjects when compared with CC genotype (OR=0.514, 95% CI=0.301-0.876, P=0.014; OR=0.518, 95% CI=0.297-0.902, P=0.020, respectively). Additionally, a risk haplotype rs4958846^C-rs10065172^C (OR=2.093, 95% CI=1.301-3.368) and a protective haplotype rs4958846^T-rs10065172^C (OR=0.652, 95% CI=0.441-0.964) were also identified to be associated with female AS. IBD-associated IRGM gene is also associated with AS susceptibility in the Chinese female population, indicating that autophagy pathway may involve in AS genetic predisposition.

Rheumatoid arthritis onset in postmenopausal women: Does the ACPA seropositive subset result from genetic effects, estrogen deficiency, skewed profile of CD4(+) T-cells, and their interactions?

Rheumatoid arthritis (RA) incidence displays a differentiated age-dependent female-to-male ratio in which women outnumber men. Evidence that the peak incidence of RA in women coincides with menopause age, suggests a potential estrogenic role to disease etiology. Estrogens exert physiologically both stimulatory and inhibitory effects on the immune system. Epidemiologic and animal model studies with estrogen deprivation or supplementation suggested estrogens as to play, mainly, a protective role in RA immunopathology. In this review, we propose that some yet unidentified disturbances associated with estrogen circulating levels, differentiated by the menopausal status, play a major role in women's RA susceptibility. We focus on the interaction between estrogen deprivation and genetic risk alleles for anti-citrullinated protein antibodies (ACPA) seropositive RA, as a major driving force for increased immune reactivity and RA susceptibility, in postmenopausal women. This opens up new fields for research concerning the association among different irregular estrogenic conditions, the cytokine milieu, and age/menopausal status bias in RA.

Environmental estrogen bisphenol A and autoimmunity

Over the past few years, there has been evidence of the increasing prevalence of autoimmune diseases. Autoimmune diseases consist of many complex disorders of unknown etiology resulting in immune responses to self-antigens. The immune system, and its function, is under complex and integrated control and its disruption can be triggered by multiple factors. Autoimmunity development is influenced by multiple factors and is thought to be a result of interactions between genetic and environmental factors. Here, we review the role of a specific environmental factor, bisphenol A (BPA), in the pathogenesis of autoimmune diseases. BPA belongs to the group of environmental estrogens that have been identified as risk factors involved in the development of autoimmune diseases.

Current understanding of pathogenesis and treatment of TMJ osteoarthritis

Osteoarthritis is a common disease that can cause severe pain and dysfunction in any joint, including the temporomandibular joint (TMJ). TMJ osteoarthritis (TMJOA) is an important subtype in the classification of temporomandibular disorders. TMJOA pathology is characterized by progressive cartilage degradation, subchondral bone remodeling, and chronic inflammation in the synovial tissue. However, the exact pathogenesis and process of TMJOA remain to be understood. An increasing number of studies have recently focused on inflammation and remodeling of subchondral bone during the early stage of TMJOA, which may elucidate the possible mechanism of initiation and progression of TMJOA. The treatment strategy for TMJOA aims at relieving pain, preventing the progression of cartilage and subchondral bone destruction, and restoring joint function. Conservative therapy with nonsteroidal anti-inflammatory drugs, splint, and physical therapy, such as low-energy laser and arthrocentesis, are the most common treatments for TMJOA. These therapies are effective in most cases in relieving the signs and symptoms, but their long-term therapeutic effect on the pathologic articular structure is unsatisfactory. A treatment that can reverse the damage of TMJOA remains unavailable to date. Treatments that prevent the progression of cartilage degradation and subchondral bone damage should be explored, and regeneration for the TMJ may provide the ideal long-term solution. This review summarizes the current understanding of mechanisms underlying the pathogenesis and treatment of TMJOA.

Analysis of the effect of the oral contraceptive pill on clinical outcomes in women with ankylosing spondylitis

OBJECTIVE

There are unexplained sex-specific changes in the clinical expression of ankylosing spondylitis (AS). We sought to examine the potential effect of exogenous estrogen in the form of oral contraceptive pills (OCP) on AS initiation and severity.

METHODS

This cross-sectional study consisted of women with AS from the membership of the Spondylitis Association of America. Measures of disease severity included use of biological agents and hip replacement surgery, while Bath AS Functional Index (BASFI) scores served as a surrogate marker of disability. Information was obtained using a patient questionnaire on patient demographics, OCP use, pregnancy history, AS duration, medication use, and hip replacement.

RESULTS

There were 571 women with AS who participated in our study, consisting of 448 OCP ever-users and 123 non-OCP users. The mean age of OCP users was 42.7 yrs (± 11.5) and of non-OCP users, 48.4 yrs (± 12.1). No difference was noted in the age at initial onset of back pain. However, OCP users were significantly younger at the time of diagnosis of AS (36.5 yrs vs 39.1 yrs, p = 0.02). There were no significant differences between the 2 groups in tumor necrosis factor inhibitor or opioid use, BASFI scores, pregnancy complications, or hip surgery.

CONCLUSION

The use of exogenous estrogens in the form of OCP is not associated with a measurable effect on initiation or severity of AS. Biologic and social factors may contribute to earlier diagnosis of AS in OCP users. This is the largest study to date investigating the potential effect of exogenous estrogens in women with AS.

Aromatase and regulation of the estrogen-to-androgen ratio in synovial tissue inflammation: common pathway in both sexes

Sex hormones play an active role in inflammatory responses, with androgens being anti-inflammatory, whereas estrogens have both pro- and anti-inflammatory effects. In rheumatoid arthritis (RA) patients, low levels of androgens and high levels of estrone are found in the synovial fluid. Aromatase is the key enzyme for the conversion of androgens into estrogens. Proinflammatory cytokines stimulate aromatase activity so that the inflammatory milieu can induce conversion of androgens to estrogens. Moreover, testosterone inhibits aromatase activity. As local androgen levels are low in RA, this can contribute to high aromatase activity in the synovium. Importantly, aromatase-converted estrogens are converted into proproliferative and proinflammatory 16-hydroxylated estrogens. A hormone involved in aromatase activity is vitamin D, which downregulates aromatase in human RA macrophages. Collectively, evidence suggests a key role of aromatase in sex hormone balance during chronic inflammation and points to the importance of vitamin D as a possible new tool for aromatase modulation.

Role of neuroendocrine and neuroimmune mechanisms in chronic inflammatory rheumatic diseases--the 10-year update

BACKGROUND

Neuroendocrine immunology in musculoskeletal diseases is an emerging scientific field. It deals with the aspects of efferent neuronal and neurohormonal bearing on the peripheral immune and musculoskeletal systems. This review aims to add new information that appeared since 2001.

SEARCH STRATEGY

The following PubMed search sentence was used to find a total of 15,462 references between 2001 and March 2013: "(rheum* OR SLE OR vasculitis) AND (nerve OR hormone OR neurotransmitter OR neuropeptide OR steroid)." In a continuous process, year by year, this search strategy yielded relevant papers that were screened and collected in a database, which build the platform of this review.

RESULTS

The main findings are the anti-inflammatory role of androgens, the loss of androgens (androgen drain), the bimodal role of estrogens (support B cells and inhibit macrophages and T cells), increased conversion of androgens to estrogens in inflammation (androgen drain), disturbances of the gonadal axis, inadequate amount of HPA axis hormones relative to inflammation (disproportion principle), biologics partly improve neuroendocrine axes, anti-corticotropin-releasing hormone therapies improve inflammation (antalarmin), bimodal role of the sympathetic nervous system (proinflammatory early, anti-inflammatory late-most probably due to catecholamine-producing local cells), anti-inflammatory role of alpha melanocyte-stimulating hormone, vasoactive intestinal peptide, and the Vagus nerve via α7 nicotinergic receptors. Circadian rhythms of hypothalamic origin are responsible for circadian rhythms of symptoms (neuroimmune link revealed). Important new pain-sensitizing immunological pathways were found in the last decade.

CONCLUSIONS

The last decade brought much new information that gave birth to the first therapies of chronic inflammatory diseases on the basis of neuroendocrine immune targets. In addition, a new theory linked evolutionary medicine, neuroendocrine regulation of distribution of energy-rich fuels, and volume regulation that can explain many disease sequelae in patients with chronic inflammatory diseases.

Sympathetic nerve fiber repulsion: testing norepinephrine, dopamine, and 17β-estradiol in a primary murine sympathetic neurite outgrowth assay

Loss of sympathetic nerve fibers (SNFs) occurs in inflamed tissue; and select semaphorins, upregulated during inflammation, stimulate repulsion/loss of SNFs. However, it is unknown whether other factors released locally in inflamed tissue, such as norepinephrine, dopamine, and 17β-estradiol, are also repellent. In order to study the effects of hormones on SNF repulsion, an SNF outgrowth assay was used. The repellent activity of semaphorins 3C was weaker than of semaphorin 3F. Tumor necrosis factor α (TNF-α) repelled nerve fibers with moderate to strong effects (from 0-100% repulsion). High concentrations of dopamine and norepinephrine (10(-6) M) induced weak but significant nerve fiber repulsion (up to 20%). Norepinephrine at 10(-8) M was comparable with 10(-6) M at inducing nerve fiber outgrowth. Stimulation with low concentrations of 17β-estradiol (10(-10) M, but not 10(-8) M) repelled SNFs. These results demonstrate that not only specific axon guidance molecules, such as semaphorins 3F and 3C, but also hormonal factors and TNF-α influence SNF repulsion and outgrowth.

Sexual dimorphisms in the immune system of catechol-O-methyltransferase knockout mice

The enzyme catechol-O-methyltransferase (COMT) is part of the metabolic pathway of 17β-estradiol, converting 2-hydroxyestradiol to 2-methoxyestradiol. We recently showed that administration of the COMT product 2-methoxyestradiol has anti-inflammatory and anti-osteoporotic effects. We have now investigated whether COMT affects the immune system, by immunologically phenotyping COMT deficient (COMT(-/-)) mice. Immunoglobulin production, T lymphocyte proliferation, NK cell cytotoxicity and oxygen radical production were assessed. In male COMT(-/-)-mice, the total number of T-, and B-lymphocytes from spleen increased but the T-cell proliferative response decreased. The NK cell population shifted toward less mature cells, leaving cytotoxic capacity unaffected. In COMT(-/-)-females, a higher frequency of neutrophils was found but the oxygen radical production was unaltered. In conclusion, only minor changes of the immune system were seen in COMT deficient mice, and the changes were usually seen in males. This study provides clues into how COMT activity, and hence gender differences, affects the immune system.

Estrogen metabolism and autoimmunity

Epidemiological and experimental immunological evidence suggest that estrogens enhance the humoral immune response, and at the same time, seem to play important roles in pathophysiology of autoimmune rheumatic diseases. Estrogens in human subjects are generally considered as enhancers of cell proliferation (anti-apoptotic), however, rather than through their serum levels (that may exert opposite dose-related effects), they play important roles through their peripheral metabolites especially in autoimmune rheumatic diseases. Several investigations strongly support an accelerated aromatase-mediated peripheral metabolic conversion of upstream androgen precursors to estrogen metabolites in peripheral tissues affected by immune/inflammatory reactions, both, in male and female patients. In RA synovial tissue, biological effects of these metabolites as a consequence of altered peripheral sex hormone synthesis (intracrine, e.g., at the level of macrophages and fibroblasts) mainly results in stimulation of cell proliferation and cytokine production (i.e. TNF). It was shown that RA synovial cells mainly produce the cell proproliferative 16alpha-hydroxyestrone which, in addition to 16alpha-hydroxy-17beta-estradiol, is the downstream estrogen metabolite that interferes with monocyte proliferation. Therefore, a preponderance of 16alpha-hydroxylated estrogens is an unfavorable sign, at least, in synovial inflammation and possibly related synovial tissue hyperplasia. Interestingly, urinary concentration and total urinary loss of 2-hydroxyestrogens was found 10 times higher in healthy subjects compared to RA or SLE patients irrespective of prior prednisolone treatment or sex. The intracrine synthesis of active estrogen metabolites at the level of cells involved in the immune response (e.g. macrophages and fibroblasts) represents a common pathway that characterizes a similar final immune reactivity in both male and female patients.

Mapping the CRF-urocortins system in human osteoarthritic and rheumatoid synovial fibroblasts: effect of vasoactive intestinal peptide

In addition to the brain and pituitary gland, the corticotrophin-releasing factor (CRF) system is expressed in peripheral tissues. In this study we characterize the expression of CRF, urocortins (UCN1, UCN2, and UCN3), and their receptors (CRFR1 and CRFR2) in osteoarthritis (OA) and rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS). Moreover, we analyze the vasoactive intestinal peptide (VIP) effect on the CRF system, as well as its physiological consequences on mediators of inflammatory/destructive processes. CRF and UCNs exhibit differential pattern in OA and RA-FLS. By real-time PCR we detected more expression of CRF and UCN1 in RA, and UCN2 and UCN3 in OA, while the CRFR2 expression was similar. In RA-FLS VIP treatment resulted in a significant decrease of the proinflammatory peptides, CRF and UCN1, and a significant increase of the potential anti-inflammatory agents, UCN3 and CRFR2. Using Western blot assays, we showed that the ratio between phospho-CREB (p-CREB) and c-AMP response element-binding (CREB) is higher in OA and significantly lower in RA-FLS after VIP treatment, with consequences upon cAMP response element in CRF and UCN1 genes. Real-time PCR and EIA proved that VIP significantly inhibits cycloxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in RA-FLS. In all cases, we consider significant data when P < 0.05. These data indicate a role of endogenous CRF, UCNs, and CRFR2 in the OA and RA joint microenvironment. We confirm the anti-inflammatory function of VIP, through the modulation of the expression of CRF system that impacts in a reduction of mediators with inflammatory/destructive functions, supporting its therapeutic potential in rheumatic diseases.

Estrogens in rheumatoid arthritis; the immune system and bone

Rheumatoid arthritis (RA) is an autoimmune disease that is more common in women than in men. The peak incidence in females coincides with menopause when the ovarian production of sex hormones drops markedly. RA is characterized by skeletal manifestations where production of pro-inflammatory mediators, connected to the inflammation in the joint, leads to bone loss. Animal studies have revealed distinct beneficial effects of estrogens on arthritis, and a positive effect of hormone replacement therapy has been reported in women with postmenopausal RA. This review will focus on the influence of female sex hormones in the pathogenesis and progression of RA.

Role of 2-methoxyestradiol as inhibitor of arthritis and osteoporosis in a model of postmenopausal rheumatoid arthritis

In postmenopausal rheumatoid arthritis, both the inflammatory disease and estrogen deficiency contribute to the development of osteoporosis. As hormone replacement therapy is no longer an option, we hypothesized that 2-methoxyestradiol (2me2) could be beneficial, and asked if such therapy was associated with effects on reproductive organs. Mice were ovariectomized and arthritis was induced, whereafter mice were administered 2me2, estradiol, or placebo. Clinical and histological scores of arthritis, together with bone mineral density were evaluated. Uteri weight, reactive oxygen species (ROS) from spleen cells, and characterization of cells from joints and lymph nodes were analyzed. In addition, in vivo activation of estrogen response elements (ERE) by 2me2 was evaluated. Treatment with 2me2 and estradiol decreased the frequency and severity of arthritis and preserved bone. Joint destruction was reduced, neutrophils diminished and ROS production decreased. The uterine weight increased upon long-term 2me2 exposure, however short-term exposure did not activate ERE in vivo.

A validated and rapid high-performance liquid chromatography method for the quantification of conversion of radio-labelled sex steroids

The 17β-hydroxysteroid dehydrogenase enzymes modify the availability of potent sex steroids and have thus attracted interest in the study of several steroid-dependent pathologies including breast, endometrial and prostate cancers. An increased awareness of the importance of steroidogenic enzymes has brought forth a demand for efficient assays to study the effects of individual enzymes on steroid levels. Methods used for assessing steroid conversion are often laborious and frequently involve hazardous sample preparation steps. We developed and validated an optimised simple method for sample preparation of sex steroids using protein precipitation by the addition of zinc sulphate/sodium hydroxide. The interconversion of radio-labelled oestrogens and androgens was quantified using high-performance liquid chromatography separation of oestrone, oestradiol, androstenedione and testosterone followed by online radiometric flow scintillation analysis. The method, which can be applied for assessing, e.g., the efficacy of inhibitors of steroidogenic enzymes, was successfully used for evaluating oestrogenic interconversion in breast cancer cell lines MCF7 and T-47D.