Menopausal hormone therapy and women's health: An umbrella review.

BACKGROUND: There remains uncertainty about the impact of menopausal hormone therapy (MHT) on women's health. A systematic, comprehensive assessment of the effects on multiple outcomes is lacking. We conducted an umbrella review to comprehensively summarize evidence on the benefits and harms of MHT across diverse health outcomes. METHODS AND FINDINGS: We searched MEDLINE, EMBASE, and 10 other databases from inception to November 26, 2017, updated on December 17, 2020, to identify systematic reviews or meta-analyses of randomized controlled trials (RCTs) and observational studies investigating effects of MHT, including estrogen-alone therapy (ET) and estrogen plus progestin therapy (EPT), in perimenopausal or postmenopausal women in all countries and settings. All health outcomes in previous systematic reviews were included, including menopausal symptoms, surrogate endpoints, biomarkers, various morbidity outcomes, and mortality. Two investigators independently extracted data and assessed methodological quality of systematic reviews using the updated 16-item AMSTAR 2 instrument. Random-effects robust variance estimation was used to combine effect estimates, and 95% prediction intervals (PIs) were calculated whenever possible. We used the term MHT to encompass ET and EPT, and results are presented for MHT for each outcome, unless otherwise indicated. Sixty systematic reviews were included, involving 102 meta-analyses of RCTs and 38 of observational studies, with 102 unique outcomes. The overall quality of included systematic reviews was moderate to poor. In meta-analyses of RCTs, MHT was beneficial for vasomotor symptoms (frequency: 9 trials, 1,104 women, risk ratio [RR] 0.43, 95% CI 0.33 to 0.57, p < 0.001; severity: 7 trials, 503 women, RR 0.29, 95% CI 0.17 to 0.50, p = 0.002) and all fracture (30 trials, 43,188 women, RR 0.72, 95% CI 0.62 to 0.84, p = 0.002, 95% PI 0.58 to 0.87), as well as vaginal atrophy (intravaginal ET), sexual function, vertebral and nonvertebral fracture, diabetes mellitus, cardiovascular mortality (ET), and colorectal cancer (EPT), but harmful for stroke (17 trials, 37,272 women, RR 1.17, 95% CI 1.05 to 1.29, p = 0.027) and venous thromboembolism (23 trials, 42,292 women, RR 1.60, 95% CI 0.99 to 2.58, p = 0.052, 95% PI 1.03 to 2.99), as well as cardiovascular disease incidence and recurrence, cerebrovascular disease, nonfatal stroke, deep vein thrombosis, gallbladder disease requiring surgery, and lung cancer mortality (EPT). In meta-analyses of observational studies, MHT was associated with decreased risks of cataract, glioma, and esophageal, gastric, and colorectal cancer, but increased risks of pulmonary embolism, cholelithiasis, asthma, meningioma, and thyroid, breast, and ovarian cancer. ET and EPT had opposite effects for endometrial cancer, endometrial hyperplasia, and Alzheimer disease. The major limitations include the inability to address the varying effects of MHT by type, dose, formulation, duration of use, route of administration, and age of initiation and to take into account the quality of individual studies included in the systematic reviews. The study protocol is publicly available on PROSPERO (CRD42017083412). CONCLUSIONS: MHT has a complex balance of benefits and harms on multiple health outcomes. Some effects differ qualitatively between ET and EPT. The quality of available evidence is only moderate to poor.

Air pollution and its effects on the immune system.

A well-functioning immune system is vital for a healthy body. Inadequate and excessive immune responses underlie diverse pathologies such as serious infections, metastatic malignancies and auto-immune conditions. Therefore, understanding the effects of ambient pollutants on the immune system is vital to understanding how pollution causes disease, and how that pathology could be abrogated. The immune system itself consists of multiple types of immune cell that act together to generate (or fail to generate) immune responses and in this article we review evidence of how air pollutants can affect different immune cell types such as particle-clearing macrophages, inflammatory neutrophils, dendritic cells that orchestrate adaptive immune responses and lymphocytes that enact those responses. Common themes that emerge are of the capacity of air pollutants to stimulate pro-inflammatory immune responses across multiple classes of immune cell. Air pollution can enhance T helper lymphocyte type 2 (Th2) and T helper lymphocyte type 17 (Th17) adaptive immune responses, as seen in allergy and asthma, and dysregulate anti-viral immune responses. The clinical effects of air pollution, in particular the known association between elevated ambient pollution and exacerbations of asthma and chronic obstructive pulmonary disease (COPD), are consistent with these identified immunological mechanisms. Further to this, as inhaled air pollution deposits primarily on the respiratory mucosa this review focuses on mechanisms of respiratory disease. However, as discussed in the article, air pollution also affects the wider immune system for example in the neonate and gastrointestinal tract. Whilst the many identified actions of air pollution on the immune system are notably diverse, immunological research does suggest potential strategies to ameliorate such effects, for example with vitamin D supplementation. An in-depth understanding of the immunological effects of ambient pollutants should hopefully yield new ideas on how to reduce the adverse health effects of air pollution.

Effects of vitamin D on inflammatory and oxidative stress responses of human bronchial epithelial cells exposed to particulate matter.

BACKGROUND: Particulate matter (PM) pollutant exposure, which induces oxidative stress and inflammation, and vitamin D insufficiency, which compromises immune regulation, are detrimental in asthma. OBJECTIVES: Mechanistic cell culture experiments were undertaken to ascertain whether vitamin D abrogates PM-induced inflammatory responses of human bronchial epithelial cells (HBECs) through enhancement of antioxidant pathways. METHODS: Transcriptome analysis, PCR and ELISA were undertaken to delineate markers of inflammation and oxidative stress; with comparison of expression in primary HBECs from healthy and asthmatic donors cultured with reference urban PM in the presence/absence of vitamin D. RESULTS: Transcriptome analysis identified over 500 genes significantly perturbed by PM-stimulation, including multiple pro-inflammatory cytokines. Vitamin D altered expression of a subset of these PM-induced genes, including suppressing IL6. Addition of vitamin D suppressed PM-stimulated IL-6 production, although to significantly greater extent in healthy versus asthmatic donor cultures. Vitamin D also differentially affected PM-stimulated GM-CSF, with suppression in healthy HBECs and enhancement in asthmatic cultures. Vitamin D increased HBEC expression of the antioxidant pathway gene G6PD, increased the ratio of reduced to oxidised glutathione, and in PM-stimulated cultures decreased the formation of 8-isoprostane. Pre-treatment with vitamin D decreased CXCL8 and further decreased IL-6 production in PM-stimulated cultures, an effect abrogated by inhibition of G6PD with DHEA, supporting a role for this pathway in the anti-inflammatory actions of vitamin D. CONCLUSIONS: In a study using HBECs from 18 donors, vitamin D enhanced HBEC antioxidant responses and modulated the immune response to PM, suggesting that vitamin D may protect the airways from pathological pollution-induced inflammation.

Exogenous sex steroid hormones and asthma in females: protocol for a population-based retrospective cohort study using a UK primary care database.

INTRODUCTION: Female sex steroid hormones have been implicated in sex-related differences in the development and clinical outcomes of asthma. The role of exogenous sex steroids, however, remains unclear. Our recent systematic review highlighted the lack of high-quality population-based studies investigating this subject. We aim to investigate whether the use of hormonal contraception and hormone replacement therapy (HRT), subtypes and route of administration are associated with asthma onset and clinical outcomes in reproductive age and perimenopausal/postmenopausal females. METHODS AND ANALYSIS: Using the Optimum Patient Care Research Database (OPCRD), a national primary care database in the UK, we will construct a retrospective longitudinal cohort of reproductive age (16-45 years) and perimenopausal/postmenopausal (46-70 years) females. We will estimate the risk of new-onset asthma using Cox regression and multilevel modelling for repeated asthma outcomes, such as asthma attacks. We will adjust for confounding factors in all analyses. We will evaluate interactions between the use of exogenous sex hormones and body mass index and smoking by calculating the relative excess risk due to interaction and the attributable proportion due to interaction. With 90% power, we need 23 700 reproductive age females to detect a 20% reduction (risk ratio 0.8) in asthma attacks for use of any hormonal contraception and 6000 perimenopausal/postmenopausal females to detect a 40% (risk ratio 1.40) increased risk of asthma attacks for use of any HRT. ETHICS AND DISSEMINATION: We have obtained approval (ADEPT1317) from the Anonymised Data Ethics and Protocol Transparency Committee which grants project-specific ethics approvals for the use of OPCRD data. Optimum Patient Care has an existing NHS Health Research Authority ethics approval for the use of OPCRD data for research (15/EM/150). We will present our findings at national and international scientific meetings and publish the results in international peer-reviewed journals. TRIAL REGISTRATION NUMBER: EUPAS22967.

Urban particulate matter stimulation of human dendritic cells enhances priming of naive CD8 T lymphocytes.

Epidemiological studies have consistently shown associations between elevated concentrations of urban particulate matter (UPM) air pollution and exacerbations of asthma and chronic obstructive pulmonary disease, which are both associated with viral respiratory infections. The effects of UPM on dendritic cell (DC) -stimulated CD4 T lymphocytes have been investigated previously, but little work has focused on CD8 T-lymphocyte responses despite their importance in anti-viral immunity. To address this, we examined the effects of UPM on DC-stimulated naive CD8 T-cell responses. Expression of the maturation/activation markers CD83, CCR7, CD40 and MHC class I on human myeloid DCs (mDCs) was characterized by flow cytometry after stimulation with UPMin vitro in the presence/absence of granulocyte-macrophage colony-stimulating factor (GM-CSF). The capacity of these mDCs to stimulate naive CD8 T-lymphocyte responses in allogeneic co-culture was then assessed by measuring T-cell cytokine secretion using cytometric bead array, and proliferation and frequency of interferon-γ (IFN-γ)-producing T lymphocytes by flow cytometry. Treatment of mDCs with UPM increased expression of CD83 and CCR7, but not MHC class I. In allogeneic co-cultures, UPM treatment of mDCs enhanced CD8 T-cell proliferation and the frequency of IFN-γ+ cells. The secretion of tumour necrosis factor-α, interleukin-13, Granzyme A and Granzyme B were also increased. GM-CSF alone, and in concert with UPM, enhanced many of these T-cell functions. The PM-induced increase in Granzyme A was confirmed in a human experimental diesel exposure study. These data demonstrate that UPM treatment of mDCs enhances priming of naive CD8 T lymphocytes and increases production of pro-inflammatory cytokines. Such UPM-induced stimulation of CD8 cells may potentiate T-lymphocyte cytotoxic responses upon concurrent airway infection, increasing bystander damage to the airways.

Interleukin 10 inhibits pro-inflammatory cytokine responses and killing of Burkholderia pseudomallei.

Melioidosis, caused by Burkholderia pseudomallei, is endemic in northeastern Thailand and Northern Australia. Severe septicemic melioidosis is associated with high levels of pro-inflammatory cytokines and is correlated with poor clinical outcomes. IL-10 is an immunoregulatory cytokine, which in other infections can control the expression of pro-inflammatory cytokines, but its role in melioidosis has not been addressed. Here, whole blood of healthy seropositive individuals (n = 75), living in N. E. Thailand was co-cultured with B. pseudomallei and production of IL-10 and IFN-γ detected and the cellular sources identified. CD3- CD14+ monocytes were the main source of IL-10. Neutralization of IL-10 increased IFN-γ, IL-6 and TNF-α production and improved bacteria killing. IFN-γ production and microbicidal activity were impaired in individuals with diabetes mellitus (DM). In contrast, IL-10 production was unimpaired in individuals with DM, resulting in an IL-10 dominant cytokine balance. Neutralization of IL-10 restored the IFN-γ response of individuals with DM to similar levels observed in healthy individuals and improved killing of B. pseudomallei in vitro. These results demonstrate that monocyte derived IL-10 acts to inhibit potentially protective cell mediated immune responses against B. pseudomallei, but may also moderate the pathological effects of excessive cytokine production during sepsis.

ASTHMA - comparing the impact of vitamin D versus UVR on clinical and immune parameters.

The incidence of asthma has increased markedly since the 1960s and is currently estimated to affect more than 300 million individuals worldwide. A number of environmental factors are implicated in asthma pathogenesis, one of which is vitamin D. Vitamin D deficiency is a global health concern and has increased in parallel with asthma incidence. Epidemiological studies report associations between low vitamin D status, assessed as circulating levels of 25-hydroxyvitamin D, with asthma incidence, severity, exacerbations and responses to treatment. This has led to clinical studies to test whether increasing the levels of vitamin D improves asthma management. Despite being highly variable in dosing regimens, design and outcomes, meta-analyses suggest overall positive outcomes with respect to reduced asthma exacerbations and steroid requirements. The primary mechanism for increasing vitamin D levels in the body is through exposure of the skin to the ultraviolet B (UVB) component of ultraviolet radiation (UVR), most commonly from sun exposure. However, only a limited number of studies investigating the impact of UVR on the asthmatic response have been performed; these generally report on the impact of latitude as a surrogate of sun exposure, or address this in animal models. To the best of our knowledge no comprehensive trials to assess the impact of UVB radiation on asthma outcomes have been performed. Within this review we discuss observational and clinical studies in this field, and innate and adaptive immune mechanisms through which UVR and vitamin D may impact respiratory health, and asthma. We highlight the heterogeneity of asthmatic disease, which is likely to impact upon the efficacy of interventional studies, and briefly overview more recent findings relating to the impact of vitamin D/UVR on the development of asthma.

1α,25-dihydroxyvitamin D3 acts via transforming growth factor-ß to up-regulate expression of immunosuppressive CD73 on human CD4+ Foxp3- T cells.

Vitamin D deficiency is associated with increased incidence and severity of various immune-mediated diseases. Active vitamin D (1α,25-dihydroxyvitamin D3; 1,25(OH)2 D3) up-regulates CD4(+) T-cell expression of the purine ectonucleotidase CD39, a molecule that is associated with the generation of anti-inflammatory adenosine. Here we aimed to investigate the direct impact of 1,25(OH)2 D3 on expression of the downstream ecto-5'-nucleotidase CD73 by human CD4 T cells, and components of the transforming growth factor-ß (TGF-ß) pathway, which have been implicated in the modulation of CD73 by murine T cells. At 10(-8) to 10(-7) m, 1,25(OH)2 D3 significantly increased expression of CD73 on peripheral human CD4(+) T cells. Although 1,25(OH)2 D3 did not affect the mRNA expression of latent TGF-ß1 , 1,25(OH)2 D3 did up-regulate expression of TGF-ß-associated molecules [latency-associated peptide (LAP), glycophorin A repetitions predominant (GARP), GP96, neuropilin-1, thrombospondin-1 and αv integrin] which is likely to have contributed to the observed enhancement in TGF-ß bioactivity. CD73 was highly co-expressed with LAP and GARP following 1,25(OH)2 D3 treatment, but unexpectedly, each of these cell surface molecules was expressed primarily on CD4(+) Foxp3(-) T cells, rather than CD4(+) Foxp3(+) T cells. Notably, neutralization of TGF-ß significantly impaired 1,25(OH)2 D3-mediated induction of CD73. Collectively, we show that 1,25(OH)2 D3 enhances expression of CD73 on CD4(+) Foxp3(-) T cells in a process that is at least partially TGF-ß-dependent. These data reveal an additional contributing mechanism by which vitamin D may be protective in immune-mediated disease.

Vitamin D influences asthmatic pathology through its action on diverse immunological pathways.

The prevalence of vitamin D insufficiency and deficiency has increased markedly in recent decades to current epidemic levels (Hyppönen E, et al. Am J Clin Nutr 2007;85:860-868). In parallel, there has been an increase in the incidence of a range of immune-mediated conditions ranging from cancer to autoimmune and respiratory diseases, including chronic obstructive pulmonary disease and asthma (Holick MF. N Engl J Med 2007;357:266-281; Finklea et al. Adv Nutr 2011;2:244-253). There is also an association with increased respiratory infections, which are the most common cause of asthma exacerbations (Finklea et al. Adv Nutr 2011;2:244-253). Together, this has resulted in considerable interest in the therapeutic potential of vitamin D to prevent and improve treatment of asthma and other respiratory diseases. To this end, data from clinical trials involving supplementation with active vitamin D, or more commonly a precursor, are starting to emerge. This review considers mechanisms by which vitamin D may act on the immune system to dampen inappropriate inflammatory responses in the airway while also promoting tolerance and antimicrobial defense mechanisms that collectively maintain respiratory health.

Urban particulate matter suppresses priming of T helper type 1 cells by granulocyte/macrophage colony-stimulating factor-activated human dendritic cells.

Urban particulate matter (UPM) exacerbates asthmatic lung inflammation and depresses lung immunity. Lung dendritic cells (DCs) react to airway particulates, and have a critical role in linking innate and adaptive immunity, but the direct effects of UPM on DCs, that have been activated by granulocyte/macrophage colony-stimulating factor (GM-CSF), a product of stimulated normal human bronchial epithelial cells, has not been investigated. Human blood CD1c(+) DCs were purified and activated with UPM in the presence or absence of GM-CSF with and without LPS, and DC maturation was assessed by flow cytometry. DC stimulatory capacity and priming of 5-(and -6)-carboxyfluorescein diacetate succinimidyl ester-labeled naive CD4 T cells was investigated using the allogeneic mixed lymphocyte reaction. T cell proliferation and effector function were assessed using flow cytometry and secreted cytokines were measured by combined bead array. UPM enhanced DC maturation in an LPS-independent manner. DCs activated by UPM plus GM-CSF (UPM + GM-CSF DCs) induced higher naive CD4 T cell proliferation in the allogeneic mixed lymphocyte reaction than DCs pretreated by GM-CSF alone (GM-CSF DCs), and elicited both substantially lower levels of IFN-γ, IL-13, and IL-5 secretion, and lower frequencies of alloantigen-specific T helper (Th) type 1 effector cells than naive CD4 T cells primed by GM-CSF DCs. UPM-stimulated DCs produced IL-6 and TNF-α. Neutralization of IL-6 decreased naive CD4 T cell proliferation stimulated by UPM + GM-CSF DCs, and significantly increased the frequency of alloantigen-specific Th1 effector cells, but did not reverse UPM-induced inhibition of IFN-γ secretion. We conclude that UPM enhances GM-CSF-induced DC maturation and stimulatory capacity, but inhibits the generation of Th1 cells. Thus, UPM exposure may impair Th1 responses to pulmonary pathogens.

Vitamin D and lung disease.

The classic role of vitamin D in the regulation of calcium and phosphate metabolism, and its effects on bone health, are well established. More recently a critical role in immunity and respiratory health has been proposed. This arises from evidence for the capacity to generate the active metabolite, 1α,25-dihydroxyvitamin D3 (1,25(OH)D3), locally in many tissues beyond the kidney; expression of the vitamin D receptor (VDR) in immune and structural cells not involved in calcium-phosphate homeostasis; and control by 1,25(OH)D3 of the transcription of genes associated with numerous different biological processes through its nuclear VDR. Abnormalities in the vitamin D axis, including a high prevalence of vitamin D insufficiency worldwide, now appear important in a wide range of pulmonary diseases including viral and bacterial respiratory infection, asthma, chronic obstructive pulmonary disease, and cancer. Actions of vitamin D on innate immune responses, for example, production of antimicrobial peptides and autophagy, and on adaptive immune responses, for example, promoting regulatory lymphocytes, are believed to underpin these associations.

Ligation of TLR9 induced on human IL-10-secreting Tregs by 1alpha,25-dihydroxyvitamin D3 abrogates regulatory function.

Signaling through the TLR family of molecular pattern recognition receptors has been implicated in the induction of innate and adaptive immune responses. A role for TLR signaling in the maintenance and/or regulation of Treg function has been proposed, however its functional relevance remains unclear. Here we have shown that TLR9 is highly expressed by human Treg secreting the antiinflammatory cytokine IL-10 induced following stimulation of blood and tissue CD3+ T cells in the presence of 1alpha,25-dihydroxyvitamin D3 (1alpha25VitD3), the active form of Vitamin D, with or without the glucocorticoid dexamethasone. By contrast, TLR9 was not highly expressed by naturally occurring CD4+CD25+ Treg or by Th1 and Th2 effector cells. Induction of TLR9, but not other TLRs, was IL-10 dependent and primarily regulated by 1alpha25VitD3 in vitro. Furthermore, ingestion of calcitriol (1alpha25VitD3) by human volunteers led to an increase of both IL-10 and TLR9 expression by CD3+CD4+ T cells analyzed directly ex vivo. Stimulation of 1alpha25VitD3-induced IL-10-secreting Treg with TLR9 agonists, CpG oligonucleotides, resulted in decreased IL-10 and IFN-gamma synthesis and a concurrent loss of regulatory function, but, unexpectedly, increased IL-4 synthesis. We therefore suggest that TLR9 could be used to monitor and potentially modulate the function of 1alpha25VitD3-induced IL-10-secreting Treg in vivo, and that this has implications in cancer therapy and vaccine design.

Vitamin D, the immune system and asthma.

The effects of vitamin D on bone metabolism and calcium homeostasis have long been recognized. Emerging evidence has implicated vitamin D as a critical regulator of immunity, playing a role in both the innate and cell-mediated immune systems. Vitamin D deficiency has been found to be associated with several immune-mediated diseases, susceptibility to infection and cancer. Recently, there has been increasing interest in the possible link between vitamin D and asthma. Further elucidation of the role of vitamin D in lung development and immune system function may hold profound implications for the prevention and treatment of asthma.

Immunological intervention in human diseases.

A recent Keystone Symposium Meeting on "Immunological Intervention in Human Disease" was held in Big Sky, Montana on January, 6-11, 2007, organized by Jacques Banchereau, Federica Sallusto and Robert Coffman. It brought together basic scientists and clinicians from both academia and the pharmaceutical industry to discuss how the immune system is involved in the development of human diseases, including cancer, allergy, autoimmunity, and infectious diseases. We highlight advances in our understanding of the pathogenesis of immune-mediated diseases and future approaches in the immune therapeutic interventions. Considerable progress in the development of model systems and methodologies to monitor human immune responses will help to develop and to evaluate new immune-based therapies at pre-clinical and clinical studies.

Regulatory T cell therapy as individualized medicine for asthma and allergy.

PURPOSE OF REVIEW: Regulatory T cells have been identified as key players in the maintenance of peripheral tolerance, which prevents inappropriate immune responses to both self-antigens and innocuous allergens. This review aims to provide an update on our current understanding of the therapeutic potential of naturally occurring and adaptive regulatory T cell subsets in allergic and asthmatic disease. RECENT FINDINGS: Evidence is emerging that regulatory T cells control aberrant immune responses to allergens in health and exhibit impaired function in active disease. These data provide a rationale for developing therapeutic strategies that promote regulatory T cell numbers or function in patients. SUMMARY: Preclinical studies of adoptive transfer of antigen-specific regulatory T cells into mouse models of allergic airway disease ameliorate the inflammatory response and in some studies airway hyperresponsiveness. Although these studies are encouraging this remains an invasive and expensive therapeutic protocol for the treatment of allergic disease in humans and a number of concerns relating to safety and efficacy exist. Existing therapies, both allergen specific immunotherapy and nonspecific treatments such as glucocorticoids, induce IL-10 secreting T regulatory populations in patients. Strategies to combine allergen immunotherapy with add-on treatments or adjuvants with the potential to boost regulatory T cells, safety and efficacy remain a major research focus.

Regulatory T cells in human disease and their potential for therapeutic manipulation.

Regulatory T cells are proposed to play a central role in the maintenance of immunological tolerance in the periphery, and studies in many animal models demonstrate their capacity to inhibit inflammatory pathologies in vivo. At a recent meeting [Clinical Application of Regulatory T Cells, 7-8 April 2005, Horsham, UK, organized by the authors of this review, in collaboration with the British Society for Immunology and Novartis] evidence was discussed that certain human autoimmune, infectious and allergic diseases are associated with impaired regulatory T-cell function. In contrast, evidence from several human cancer studies and some infections indicates that regulatory T cells may impair the development of protective immunity. Importantly, certain therapies, both those that act non-specifically to reduce inflammation and antigen-specific immunotherapies, may induce or enhance regulatory T-cell function. The purpose of this review was to summarize current knowledge on regulatory T-cell function in human disease, and to assess critically how this can be tailored to suit the therapeutic manipulation of immunity.