Defective proliferative capacity and accelerated telomeric loss of hematopoietic progenitor cells in rheumatoid arthritis

T cell aging as a risk factor for autoimmunity

Immune aging is a complex process rendering the host susceptible to cancer, infection, and insufficient tissue repair. Many autoimmune diseases preferentially occur during the second half of life, counterintuitive to the concept of excess adaptive immunity driving immune-mediated tissue damage. T cells are particularly susceptible to aging-imposed changes, as they are under extreme proliferative pressure to fulfill the demands of clonal expansion and of homeostatic T cell repopulation. T cells in older adults have a footprint of genetic and epigenetic changes, lack mitochondrial fitness, and fail to maintain proteostasis, diverging them from host protection to host injury. Here, we review recent progress in understanding how the human T-cell system ages and the evidence detailing how T cell aging contributes to autoimmune conditions. T cell aging is now recognized as a risk determinant in two prototypic autoimmune syndromes; rheumatoid arthritis and giant cell arteritis. The emerging concept adds susceptibility to autoimmune and autoinflammatory disease to the spectrum of aging-imposed adaptations and opens new opportunities for immunomodulatory therapy by restoring the functional intactness of aging T cells.

Functions and regulatory mechanisms of resting hematopoietic stem cells: a promising targeted therapeutic strategy

Hematopoietic stem cells (HSCs) are the common and essential precursors of all blood cells, including immune cells, and they are responsible for the lifelong maintenance and damage repair of blood tissue homeostasis. The vast majority (> 95%) of HSCs are in a resting state under physiological conditions and are only activated to play a functional role under stress conditions. This resting state affects their long-term survival and is also closely related to the lifelong maintenance of hematopoietic function; however, abnormal changes may also be an important factor leading to the decline of immune function in the body and the occurrence of diseases in various systems. While the importance of resting HSCs has attracted increasing research attention, our current understanding of this topic remains insufficient, and the direction of clinical targeted treatments is unclear. Here, we describe the functions of HSCs, analyze the regulatory mechanisms that affect their resting state, and discuss the relationship between resting HSCs and different diseases, with a view to providing guidance for the future clinical implementation of related targeted treatments.

The regulatory feedback of inflammatory signaling and telomere/telomerase complex dysfunction in chronic inflammatory diseases

Inflammation is believed to play a role in the progression of numerous human diseases. Research has shown that inflammation and telomeres are involved in a feedback regulatory loop: inflammation increases the rate of telomere attrition, leading to telomere dysfunction, while telomere components also participate in regulating the inflammatory response. However, the specific mechanism behind this feedback loop between inflammatory signaling and telomere/telomerase complex dysfunction has yet to be fully understood. This review presents the latest findings on this topic, with a particular focus on the detailed regulation and molecular mechanisms involved in the progression of aging, various chronic inflammatory diseases, cancers, and different stressors. Several feedback loops between inflammatory signaling and telomere/telomerase complex dysfunction, including NF-κB-TERT feedback, NF-κB-RAP1 feedback, NF-κB-TERC feedback, STAT3-TERT feedback, and p38 MAPK-shelterin complex-related gene feedback, are summarized. Understanding the latest discoveries of this feedback regulatory loop can help identify novel potential drug targets for the suppression of various inflammation-associated diseases.

Age-related mechanisms in the context of rheumatic disease

Ageing is characterized by a progressive loss of cellular function that leads to a decline in tissue homeostasis, increased vulnerability and adverse health outcomes. Important advances in ageing research have now identified a set of nine candidate hallmarks that are generally considered to contribute to the ageing process and that together determine the ageing phenotype, which is the clinical manifestation of age-related dysfunction in chronic diseases. Although most rheumatic diseases are not yet considered to be age related, available evidence increasingly emphasizes the prevalence of ageing hallmarks in these chronic diseases. On the basis of the current evidence relating to the molecular and cellular ageing pathways involved in rheumatic diseases, we propose that these diseases share a number of features that are observed in ageing, and that they can therefore be considered to be diseases of premature or accelerated ageing. Although more data are needed to clarify whether accelerated ageing drives the development of rheumatic diseases or whether it results from the chronic inflammatory environment, central components of age-related pathways are currently being targeted in clinical trials and may provide a new avenue of therapeutic intervention for patients with rheumatic diseases.

T-Cell Aging-Associated Phenotypes in Autoimmune Disease

The aging process causes profound restructuring of the host immune system, typically associated with declining host protection against cancer and infection. In the case of T cells, aging leads to the accumulation of a diverse set of T-cell aging-associated phenotypes (TASP), some of which have been implicated in driving tissue inflammation in autoimmune diseases. T cell aging as a risk determinant for autoimmunity is exemplified in two classical autoimmune conditions: rheumatoid arthritis (RA), a disease predominantly affecting postmenopausal women, and giant cell arteritis (GCA), an inflammatory vasculopathy exclusively occurring during the 6th-9th decade of life. Pathogenic T cells in RA emerge as a consequence of premature immune aging. They have shortening and fragility of telomeric DNA ends and instability of mitochondrial DNA. As a result, they produce a distinct profile of metabolites, disproportionally expand their endoplasmic reticulum (ER) membranes and release excess amounts of pro-inflammatory effector cytokines. Characteristically, they are tissue invasive, activate the inflammasome and die a pyroptotic death. Patients with GCA expand pathogenic CD4⁺ T cells due to aberrant expression of the co-stimulatory receptor NOTCH1 and the failure of the PD-1/PD-L1 immune checkpoint. In addition, GCA patients lose anti-inflammatory Treg cells, promoting tissue-destructive granulomatous vasculitis. In summary, emerging data identify T cell aging as a risk factor for autoimmune disease and directly link TASPs to the breakdown of T cell tolerance and T-cell-induced tissue inflammation.

Molecular Mechanisms of Immunosenescene and Inflammaging: Relevance to the Immunopathogenesis and Treatment of Multiple Sclerosis

Aging is characterized, amongst other features, by a complex process of cellular senescence involving both innate and adaptive immunity, called immunosenescence and associated to inflammaging, a low-grade chronic inflammation. Both processes fuel each other and partially explain increasing incidence of cancers, infections, age-related autoimmunity, and vascular disease as well as a reduced response to vaccination. Multiple sclerosis (MS) is a lifelong disease, for which considerable progress in disease-modifying therapies (DMTs) and management has improved long-term survival. However, disability progression, increasing with age and disease duration, remains. Neurologists are now involved in caring for elderly MS patients, with increasing comorbidities. Aging of the immune system therefore has relevant implications for MS pathogenesis, response to DMTs and the risks mediated by these treatments. We propose to review current evidence regarding markers and molecular mechanisms of immunosenescence and their relevance to understanding MS pathogenesis. We will focus on age-related changes in the innate and adaptive immune system in MS and other auto-immune diseases, such as systemic lupus erythematosus and rheumatoid arthritis. The consequences of these immune changes on MS pathology, in interaction with the intrinsic aging process of central nervous system resident cells will be discussed. Finally, the impact of immunosenescence on disease evolution and on the safety and efficacy of current DMTs will be presented.

Bridging Insights From Lymph Node and Synovium Studies in Early Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease of unknown etiology characterized by inflammation of the peripheral synovial joints leading to pannus formation and bone destruction. Rheumatoid Factor (RF) and anti-citrullinated protein antibodies (ACPA) are present years before clinical manifestations and are indicative of a break in tolerance that precedes chronic inflammation. The majority of studies investigating disease pathogenesis focus on the synovial joint as target site of inflammation while few studies explore the initial break in peripheral tolerance which occurs within secondary lymphoid organs such as lymph nodes. If explored during the earliest phases of RA, lymph node research may provide innovative drug targets for disease modulation or prevention. RA research largely centers on the role and origin of lymphocytes, such as pro-inflammatory T cells and macrophages that infiltrate the joint, as well as growing efforts to determine the role of stromal cells within the synovium. It is therefore important to explore these cell types also within the lymph node as a number of mouse studies suggest a prominent immunomodulatory role for lymph node stromal cells. Synovium and proximal peripheral lymph nodes should be investigated in conjunction with one another to gain understanding of the immunological processes driving RA progression from systemic autoimmunity toward synovial inflammation. This perspective seeks to provide an overview of current literature concerning the immunological changes present within lymph nodes and synovium during early RA. It will also propose areas that warrant further exploration with the aim to uncover novel targets to prevent disease progression.

Telomeres: New players in immune-mediated inflammatory diseases?

Telomeres are repetitive DNA sequences located at the ends of linear chromosomes that preserve the integrity and stability of the genome. Telomere dysfunctions due to short telomeres or altered telomere structures can ultimately lead to replicative cellular senescence and chromosomal instability, both mechanisms being hallmarks of ageing. Chronic inflammation, oxidative stress and finally telomere length (TL) dynamics have been shown to be involved in various age-related non-communicable diseases (NCDs). Immune-mediated inflammatory diseases (IMIDs), including affections such as inflammatory bowel disease, psoriasis, rheumatoid arthritis, spondyloarthritis and uveitis belong to this group of age-related NCDs. Although in recent years, we have witnessed the emergence of studies in the literature linking these IMIDs to TL dynamics, the causality between these diseases and telomere attrition is still unclear and controversial. In this review, we provide an overview of available studies on telomere dynamics and discuss the utility of TL measurements in immune-mediated inflammatory diseases.

External environmental agents influence telomere length and telomerase activity by modulating internal cellular processes: Implications in human aging

External environment affects cellular physiological processes and impact the stability of our genome. The most important structural components of our linear chromosomes which endure the impact by these agents, are the chromosomal ends called telomeres. Telomeres preserve the integrity of our genome by preventing end to end fusions and telomeric loss through by inhibiting DNA damage response (DDR) activation. This is accomplished by the presence of a six membered shelterin complex at telomeres. Further, telomeres cannot be replicated by normal DNA polymerase and require a special enzyme called telomerase which is expressed only in stem cells, few immune cells and germ cells. Telomeres are rich in guanine content and thus become extremely prone to damage arising due to physiological processes like oxidative stress and inflammation. External environmental factors which includes various physical, biological and chemical agents also affect telomere homeostasis by increasing oxidative stress and inflammation. In the present review, we highlight the effect of these external factors on telomerase activity and telomere length. We also discuss how the external agents affect the physiological processes, thus modulating telomere stability. Further, we describe its implication in the development of aging and its related pathologies.

Inflammation as a regulator of hematopoietic stem cell function in disease, aging, and clonal selection

Inflammation is an evolutionarily selected defense response to infection or tissue damage that involves activation and consumption of immune cells in order to reestablish and maintain organismal integrity. In this process, hematopoietic stem cells (HSCs) are themselves exposed to inflammatory cues and via proliferation and differentiation, replace mature immune cells in a demand-adapted fashion. Here, we review how major sources of systemic inflammation act on and subsequently shape HSC fate and function. We highlight how lifelong inflammatory exposure contributes to HSC inflamm-aging and selection of premalignant HSC clones. Finally, we explore emerging areas of interest and open questions remaining in the field.

The immunology of rheumatoid arthritis

The immunopathogenesis of rheumatoid arthritis (RA) spans decades, beginning with the production of autoantibodies against post-translationally modified proteins (checkpoint 1). After years of asymptomatic autoimmunity and progressive immune system remodeling, tissue tolerance erodes and joint inflammation ensues as tissue-invasive effector T cells emerge and protective joint-resident macrophages fail (checkpoint 2). The transition of synovial stromal cells into autoaggressive effector cells converts synovitis from acute to chronic destructive (checkpoint 3). The loss of T cell tolerance derives from defective DNA repair, causing abnormal cell cycle dynamics, telomere fragility and instability of mitochondrial DNA. Mitochondrial and lysosomal anomalies culminate in the generation of short-lived tissue-invasive effector T cells. This differentiation defect builds on a metabolic platform that shunts glucose away from energy generation toward the cell building and motility programs. The next frontier in RA is the development of curative interventions, for example, reprogramming T cell defects during the period of asymptomatic autoimmunity.

Regulatory T Cells: Concept, Classification, Phenotype, and Biological Characteristics

Regulatory T cells (Treg) play an indispensable role in maintaining the body's immune nonresponse to self-antigens and suppressing the body's unwarranted and potentially harmful immune responses. Their absence, reduction, dysfunction, transformation, and instability can lead to numerous autoimmune diseases. There are several distinct subtypes of the Treg cells, although they share certain biological characteristics and have unique phenotypes with different regulatory functions, as well as mechanistic abilities. In this book chapter, we introduce the latest advances in Treg cell subtypes pertaining to classification, phenotype, biological characteristics, and mechanisms. We also highlight the relationship between Treg cells and various diseases, including autoimmune, infectious, as well as tumors and organ transplants.

Association of telomere length with risk of rheumatoid arthritis: a meta-analysis and Mendelian randomization

OBJECTIVE

To evaluate the telomere length (TL) in patients with RA relative to that in controls and to test whether TL is causally associated with risk of RA.

METHODS

Systematic review and meta-analysis of relevant literature was conducted to evaluate the association between TL and RA. Standardized mean differences with 95% CIs of TL in RA patients relative to controls were pooled using fixed or random-effects models. TL-related single-nucleotide polymorphisms were selected from a genome-wide association study of 37 684 individuals, and summary statistics of RA were obtained from a genome-wide association study meta-analysis including 14 361 RA patients and 43 923 controls. Mendelian randomization was performed using the inverse-variance weighted, weighted-median and likelihood-based methods. Sensitivity analyses were performed to test the robustness of the association.

RESULTS

In the meta-analysis of 911 RA patients and 2498 controls, we found that patients with RA had a significantly shorter TL compared with controls (standardized mean differences = -0.50; 95% CI -0.88, -0.11; P = 0.012). In the Mendelian randomization analysis, we found that genetically predicted longer TL was associated with a reduced risk of RA [odds ratio = 0.68; 95% CI 0.54, 0.86; P = 0.002 using the inverse-variance weighted method]. Sensitivity analyses using alternative Mendelian randomization approaches yielded similar findings, suggesting the robustness of the causal association.

CONCLUSION

Our study provides evidence for a negative causal association of TL with risk of RA. Further studies are warranted to elucidate the underlying mechanism for the role of telomeres in the development of RA.

Association between shorter leukocyte telomeres and multiple sclerosis

Relative telomere length (TL) is regarded as a biomarker of biological age. Accelerated immune aging, as represented by TL reduction, has been demonstrated in autoimmune diseases, including multiple sclerosis (MS). However, it is still unresolved whether telomere shortening is the cause or the consequence of the pathogenic events underlying autoimmunity. Assessing TL in whole blood DNA samples in 138 MS patients and 120 healthy controls showed reduced TL in patients as compared with controls There seems to be a prelude of accelerated telomere shortening, which may increase the risk for development of MS.

Heterogeneous Responses of Hematopoietic Stem Cells to Inflammatory Stimuli Are Altered with Age

Long-term hematopoietic stem cells (LT-HSCs) maintain hematopoietic output throughout an animal's lifespan. However, with age, the balance is disrupted, and LT-HSCs produce a myeloid-biased output, resulting in poor immune responses to infectious challenge and the development of myeloid leukemias. Here, we show that young and aged LT-HSCs respond differently to inflammatory stress, such that aged LT-HSCs produce a cell-intrinsic, myeloid-biased expression program. Using single-cell RNA sequencing (scRNA-seq), we identify a myeloid-biased subset within the LT-HSC population (mLT-HSCs) that is prevalent among aged LT-HSCs. We identify CD61 as a marker of mLT-HSCs and show that CD61-high LT-HSCs are uniquely primed to respond to acute inflammatory challenge. We predict that several transcription factors regulate the mLT-HSCs gene program and show that Klf5, Ikzf1, and Stat3 play an important role in age-related inflammatory myeloid bias. We have therefore identified and isolated an LT-HSC subset that regulates myeloid versus lymphoid balance under inflammatory challenge and with age.

Where to Stand with Stromal Cells and Chronic Synovitis in Rheumatoid Arthritis?

The synovium exercises its main function in joint homeostasis through the secretion of factors (such as lubricin and hyaluronic acid) that are critical for the joint lubrication and function. The main synovium cell components are fibroblast-like synoviocytes, mesenchymal stromal/stem cells and macrophage-like synovial cells. In the synovium, cells of mesenchymal origin modulate local inflammation and fibrosis, and interact with different fibroblast subtypes and with resident macrophages. In pathologic conditions, such as rheumatoid arthritis, fibroblast-like synoviocytes proliferate abnormally, recruit mesenchymal stem cells from subchondral bone marrow, and influence immune cell activity through epigenetic and metabolic adaptations. The resulting synovial hyperplasia leads to secondary cartilage destruction, joint swelling, and pain. In the present review, we summarize recent findings on the molecular signature and the roles of stromal cells during synovial pannus formation and rheumatoid arthritis progression.

Telomeres, Telomerase and Ageing

Telomeres are specialised structures at the end of linear chromosomes. They consist of tandem repeats of the hexanucleotide sequence TTAGGG, as well as a protein complex called shelterin. Together, they form a protective loop structure against chromosome fusion and degradation. Shortening or damage to telomeres and opening of the loop induce an uncapped state that triggers a DNA damage response resulting in senescence or apoptosis.Average telomere length, usually measured in human blood lymphocytes, was thought to be a biomarker for ageing, survival and mortality. However, it becomes obvious that regulation of telomere length is very complex and involves multiple processes. For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. In addition, telomeres can be transcribed, and the transcription products called TERRA are involved in telomere length regulation.Thus, telomere length and their integrity are regulated at many different levels, and we only start to understand this process under conditions of increased oxidative stress, inflammation and during diseases as well as the ageing process.This chapter aims to describe our current state of knowledge on telomeres and telomerase and their regulation in order to better understand their role for the ageing process.

Pro-inflammatory cytokine blockade attenuates myeloid expansion in a murine model of rheumatoid arthritis

Rheumatoid arthritis (RA) is a debilitating autoimmune disease characterized by chronic inflammation and progressive destruction of joint tissue. It is also characterized by aberrant blood phenotypes including anemia and suppressed lymphopoiesis that contribute to morbidity in RA patients. However, the impact of RA on hematopoietic stem cells (HSC) has not been fully elucidated. Using a collagen-induced mouse model of human RA, we identified systemic inflammation and myeloid overproduction associated with activation of a myeloid differentiation gene program in HSC. Surprisingly, despite ongoing inflammation, HSC from arthritic mice remain in a quiescent state associated with activation of a proliferation arrest gene program. Strikingly, we found that inflammatory cytokine blockade using the interleukin-1 receptor antagonist anakinra led to an attenuation of inflammatory arthritis and myeloid expansion in the bone marrow of arthritic mice. In addition, anakinra reduced expression of inflammation-driven myeloid lineage and proliferation arrest gene programs in HSC of arthritic mice. Altogether, our findings show that inflammatory cytokine blockade can contribute to normalization of hematopoiesis in the context of chronic autoimmune arthritis.

Seno-suppressive molecules as new therapeutic perspectives in rheumatic diseases

Over the past years, through in vitro studies and unique animal models, biologists and clinicians have demonstrated that cellular senescence is at the root of numerous age-related chronic diseases including osteoarthritis and osteoporosis. This non-proliferative cellular syndrome can modify other surrounding tissue-resident cells through the establishment of a deleterious catabolic and inflammatory microenvironment. Targeting these deleterious cells through local or systemic seno-therapeutic agent delivery in pre-clinical models improves dramatically clinical signs and extends health span. In this review, we will summarize the current knowledge on cellular senescence, list the different strategies for identifying seno-suppressive therapeutic agents and their translations to rheumatic diseases.

Telomere dysfunction-related serological markers and oxidative stress markers in rheumatoid arthritis patients: correlation with diseases activity

Rheumatoid arthritis (RA) is an inflammatory autoimmune polyarthritis with progressive destruction of the synovial joints associated with systemic manifestations. RA is characterized by infiltration of the synovial joints with inflammatory immune cells with premature immunosenescence. Shorter telomere length in the peripheral blood cells and increase in the oxidative stress have been detected in patients with RA. The aim of the present study was to study the association of markers of telomere shortening and oxidative stress with RA disease activity. Sixty-one RA patients and 15 healthy controls were enrolled in the study. Demographic data, clinical examination, and disease activity status were evaluated for the RA patients. Serum levels of chitinase and NAG (telomere markers) were determined by biochemical reactions using colloidal chitin and NAG as substrates, respectively. Nitric oxide and superoxide dismutase (oxidative stress markers) were determined colometrically and spectrophotometrically, respectively, in the sera of RA patients and controls. Results were correlated with disease activity. Indices of telomere shortening and oxidative markers were significantly higher in RA patients compared to controls. These indices were correlated with signs of disease activity (including number of swollen and tender joints, DAS-28, and inflammatory markers). Rheumatoid arthritis is a disease in which markers of telomere shortening and elevated oxidant stress correlate with disease activity.

Mycophenolic acid induces senescence of vascular precursor cells

OBJECTIVE

Endothelial dysfunction is central to the pathogenesis of many rheumatic diseases, typified by vascular inflammation and damage. Immunosuppressive drugs induce disease remission and lead to improved patient survival. However, there remains a higher incidence of cardiovascular disease in these patients even after adequate disease control. The purpose of this study was to determine the effect of mycophenolic acid (MPA), a commonly used immunosuppressive drug in rheumatology, on blood vessel or circulating endothelial colony forming cell number and function.

METHODS

We tested whether mycophenolic acid exerts an inhibitory effect on proliferation, clonogenic potential and vasculogenic function of endothelial colony forming cell. We also studied potential mechanisms involved in the observed effects.

RESULTS

Treatment with MPA decreased endothelial colony forming cell proliferation, clonogenic potential and vasculogenic function in a dose-dependent fashion. MPA increased senescence-associated β-galactosidase expression, p21 gene expression and p53 phosphorylation, indicative of activation of cellular senescence. Exogenous guanosine supplementation rescued diminished endothelial colony forming cell proliferation and indices of senescence, consistent with the known mechanism of action of MPA.

CONCLUSION

Our findings show that clinically relevant doses of MPA have potent anti-angiogenic and pro-senescent effects on vascular precursor cells in vitro, thus indicating that treatment with MPA can potentially affect vascular repair and regeneration. This warrants further studies in vivo to determine how MPA therapy contributes to vascular dysfunction and increased cardiovascular disease seen in patients with inflammatory rheumatic disease.

Aging of the Immune System. Mechanisms and Therapeutic Targets

Beginning with the sixth decade of life, the human immune system undergoes dramatic aging-related changes, which continuously progress to a state of immunosenescence. The aging immune system loses the ability to protect against infections and cancer and fails to support appropriate wound healing. Vaccine responses are typically impaired in older individuals. Conversely, inflammatory responses mediated by the innate immune system gain in intensity and duration, rendering older individuals susceptible to tissue-damaging immunity and inflammatory disease. Immune system aging functions as an accelerator for other age-related pathologies. It occurs prematurely in some clinical conditions, most prominently in patients with the autoimmune syndrome rheumatoid arthritis (RA); and such patients serve as an informative model system to study molecular mechanisms of immune aging. T cells from patients with RA are prone to differentiate into proinflammatory effector cells, sustaining chronic-persistent inflammatory lesions in the joints and many other organ systems. RA T cells have several hallmarks of cellular aging; most importantly, they accumulate damaged DNA. Because of deficiency of the DNA repair kinase ataxia telangiectasia mutated, RA T cells carry a higher burden of DNA double-strand breaks, triggering cell-indigenous stress signals that shift the cell's survival potential and differentiation pattern. Immune aging in RA T cells is also associated with metabolic reprogramming; specifically, with reduced glycolytic flux and diminished ATP production. Chronic energy stress affects the longevity and the functional differentiation of older T cells. Altered metabolic patterns provide opportunities to therapeutically target the immune aging process through metabolic interference.

Increased IL-6 secretion by aged human mesenchymal stromal cells disrupts hematopoietic stem and progenitor cells' homeostasis

Hematopoietic stem and progenitor cell (HSPC) homeostasis declines with age, leading to impaired hematopoiesis. Mesenchymal stromal cells (MSC) are critical components of the bone marrow niche and key regulators of the balance between HSPC proliferation and quiescence. Accrual of DNA damage, a hallmark of cellular aging, occurs in aged MSC. Whether MSC aging alters the bone marrow niche triggering HSPC dysfunction is unknown. Using a human MSC-HSPC co-culture system, we demonstrated that DNA damaged MSC have impaired capacity to maintain CD34⁺CD38⁻ HSPC quiescence. Furthermore, human MSC from adult donors display some hallmarks of cellular senescence and have a decreased capacity to maintain HSPC quiescence and the most primitive CD34⁺CD38⁻ subset compared to MSC from pediatric donors. IL-6 neutralization restores the MSC-HPSC crosstalk in senescent and adult MSC-HSPC co-cultures highlighting the relevance of the local microenvironment in maintaining HSPC homeostasis. These results provide new evidence implicating components of the MSC secretome in HSPC aging.

Inflammation: a key regulator of hematopoietic stem cell fate in health and disease

Hematopoietic stem cells (HSCs) are responsible for lifelong production of blood cells. At the same time, they must respond rapidly to acute needs such as infection or injury. Significant interest has emerged in how inflammation regulates HSC fate and how it affects the long-term functionality of HSCs and the blood system as a whole. Here we detail recent advances and unanswered questions at the intersection between inflammation and HSC biology in the contexts of development, aging, and hematological malignancy.

High levels of soluble GPR56/ADGRG1 are associated with positive rheumatoid factor and elevated tumor necrosis factor in patients with rheumatoid arthritis

BACKGROUND

GPR56/ADGRG1 is a member of the adhesion-class G protein-coupled receptor (aGPCR) family important in brain development, oncogenesis and tumor metastasis. Like other aGPCRs, GPR56 is cleaved at the GPCR proteolysis site (GPS) motif into an N-terminal fragment (NTF) and a C-terminal fragment (CTF). Existence of soluble GPR56 (sGPR56) has been shown in vitro, however the underlying mechanism and its pathophysiologic role remains undetermined.

OBJECTIVE

To assess the presence of sGPR56 in human serum using ELISA assay and compare the serum sGPR56 levels among patients of various chronic inflammatory diseases and healthy subjects.

PATIENTS AND METHODS

In this study, serum samples from patients with systemic lupus erythematosus (SLE) (n = 57), rheumatoid arthritis (RA) (n = 95), Sjögren's syndrome (SS) (n = 29), ankylosing spondylitis (AS) (n = 51), and normal controls (n = 81) were analyzed using sGPR56-specific ELISA.

RESULT

We show that serum sGPR56 levels are increased in patients of RA, but not in those with SLE, SS and AS. Intriguingly, serum sGPR56 levels in RA patients correlated with positive rheumatoid factor, a marker of bone erosion and poor outcome. In addition, an elevated sGPR56 level is also noted in RA patients with higher tumor necrosis factor level.

CONCLUSION

we conclude that sGPR56 is present in vivo and sGPR56 level is elevated in certain chronic inflammatory diseases such as RA. Hence, sGPR56 might be considered a potential biomarker for RA disease progression.

Development of software and modification of Q-FISH protocol for estimation of individual telomere length in immunopathology

Telomere length is an important indicator of proliferative cell history and potential. Decreasing telomere length in the cells of an immune system can indicate immune aging in immune-mediated and chronic inflammatory diseases. Quantitative fluorescent in situ hybridization (Q-FISH) of a labeled (C3TA[Formula: see text] peptide nucleic acid probe onto fixed metaphase cells followed by digital image microscopy allows the evaluation of telomere length in the arms of individual chromosomes. Computer-assisted analysis of microscopic images can provide quantitative information on the number of telomeric repeats in individual telomeres. We developed new software to estimate telomere length. The MeTeLen software contains new options that can be used to solve some Q-FISH and microscopy problems, including correction of irregular light effects and elimination of background fluorescence. The identification and description of chromosomes and chromosome regions are essential to the Q-FISH technique. To improve the quality of cytogenetic analysis after Q-FISH, we optimized the temperature and time of DNA-denaturation to get better DAPI-banding of metaphase chromosomes. MeTeLen was tested by comparing telomere length estimations for sister chromatids, background fluorescence estimations, and correction of nonuniform light effects. The application of the developed software for analysis of telomere length in patients with rheumatoid arthritis was demonstrated.

DNA damage-dependent mechanisms of ageing and disease in the macro- and microvasculature

A decline in the function of the macro- and micro-vasculature occurs with ageing. DNA damage also accumulates with ageing, and thus DNA damage and repair have important roles in physiological ageing. Considerable evidence also supports a crucial role for DNA damage in the development and progression of macrovascular disease such as atherosclerosis. These findings support the concept that prolonged exposure to risk factors is a major stimulus for DNA damage within the vasculature, in part via the generation of reactive oxygen species. Genomic instability can directly affect vascular cellular function, leading to cell cycle arrest, apoptosis and premature vascular cell senescence. In contrast, the study of age-related impaired function and DNA damage mechanisms in the microvasculature is limited, although ageing is associated with microvessel endothelial dysfunction. This review examines current knowledge on the role of DNA damage and DNA repair systems in macrovascular disease such as atherosclerosis and microvascular disease. We also discuss the cellular responses to DNA damage to identify possible strategies for prevention and treatment.

The Telomere/Telomerase System in Chronic Inflammatory Diseases. Cause or Effect?

Telomeres are specialized nucleoprotein structures located at the end of linear chromosomes and telomerase is the enzyme responsible for telomere elongation. Telomerase activity is a key component of many cancer cells responsible for rapid cell division but it has also been found by many laboratories around the world that telomere/telomerase biology is dysfunctional in many other chronic conditions as well. These conditions are characterized by chronic inflammation, a situation mostly overlooked by physicians regarding patient treatment. Among others, these conditions include diabetes, renal failure, chronic obstructive pulmonary disease, etc. Since researchers have in many cases identified the association between telomerase and inflammation but there are still many missing links regarding this correlation, the latest findings about this phenomenon will be discussed by reviewing the literature. Our focus will be describing telomere/telomerase status in chronic diseases under the prism of inflammation, reporting molecular findings where available and proposing possible future approaches.

Rheumatoid Arthritis, Immunosenescence and the Hallmarks of Aging

Age is the most important risk factor for the development of infectious diseases, cancer and chronic inflammatory diseases including rheumatoid arthritis (RA). The very act of living causes damage to cells. A network of molecular, cellular and physiological maintenance and repair systems creates a buffering capacity against these damages. Aging leads to progressive shrinkage of the buffering capacity and increases vulnerability. In order to better understand the complex mammalian aging processes, nine hallmarks of aging and their interrelatedness were recently put forward.

RA is a chronic autoimmune disease affecting the joints. Although RA may develop at a young age, the incidence of RA increases with age. It has been suggested that RA may develop as a consequence of premature aging (immunosenescence) of the immune system. Alternatively, premature aging may be the consequence of the inflammatory state in RA. In an effort to answer this chicken and egg conundrum, we here outline and discuss the nine hallmarks of aging, their contribution to the pre-aged phenotype and the effects of treatment on the reversibility of immunosenescence in RA.

Control of stress signaling in stem cells: crossroads of stem cells and cancer

Tumorigenesis is a relatively rare event in the human body considering the enormous number of cells composing our body and the frequent occurrence of genetic mutations in each cell. Nevertheless, the cells that happen to meet the minimum requirements can be transformed when stressed by a variety of oncogenic stimulations, then progress to form tumors. The vigorous competition between oncogenic signaling and tumor-suppressor defense is a critical determinant of cellular fate, which can be either tumorigenic transformation or cellular senescence/apoptosis depending on "who wins the battle." Recently, a number of cancers have been reported to originate from stem cells, whose self-renewing properties are normally reduced by innate tumor suppressors. Therefore, exploring the innate mechanism by which stem cells modulate tumor suppressors to maintain their "stemness" may provide valuable clues to characterize the distinctive oncogenic susceptibility of stem cells. This review is focused on the recent advances in the field of tumorigenesis of stem cells and on the associated molecular mechanisms.

CD3(+)CD8(+)CD28(-) T Lymphocytes in Patients with Lupus Nephritis

The results of studies on the CD3⁺CD8⁺CD28⁻ cells in SLE are inconsistent since several analyses describe CD3⁺CD8⁺CD28⁻ as either immunosuppressive or cytotoxic. The aim of this study is to inquire whether the quantitative changes of CD3⁺CD8⁺CD28⁻ T lymphocytes subpopulation are related to the clinical status of patients with lupus nephritis. Evaluation of Foxp3 expression on CD3⁺CD8⁺CD28⁻ cells may shed some light on functional properties of these cells. 54 adult SLE patients and 19 sex and age matched healthy volunteers were enrolled in the study. There were 15 patients in inactive (SLEDAI ≤ 5) and 39 in active (SLEDAI > 5) phase of disease. We determined absolute count of CD3⁺CD8⁺CD28⁻ and CD3⁺CD8⁺CD28⁻Foxp3⁺ subpopulations by flow cytometry. We observed a statistically significant increase in absolute count and percentage of CD3⁺CD8⁺CD28⁻ in SLE patients compared to HC (p < 0.001). Moreover there was significant positive correlation between increasing absolute count of CD3⁺CD8⁺CD28⁻ cells and disease activity measured by SLEDAI (rs = 0.281, p = 0.038). Active LN patients had increased absolute count of CD3⁺CD8⁺CD28⁻ cells compared to HC. Positive correlation of CD3⁺CD8⁺CD28⁻ number with disease activity, and lack of Foxp3 expression on these cells, suggests that CD3⁺CD8⁺CD28⁻ lymphocytes might be responsible for an increased proinflammatory response in the exacerbation of SLE.

Telomere Length and Coronary Atherosclerosis in Rheumatoid Arthritis

OBJECTIVE

Telomeres protect against chromosomal end damage and shorten with each cell division; their length may be a marker of cardiovascular and overall biological aging. We examined the hypothesis that reduced telomere length is associated with increased coronary atherosclerosis in rheumatoid arthritis (RA).

METHODS

We performed a cross-sectional study in 145 patients with RA and 87 control subjects frequency-matched for age, race, and sex. Coronary artery calcium score was determined by noncontrast cardiac computed tomography. Telomere length was measured from whole blood DNA, using real-time quantitative polymerase chain reaction and expressed as telomeric product to a single-copy gene product ratio (T/S ratio). Associations between telomere length, coronary artery calcium score, and 28-joint Disease Activity Score (DAS28) were assessed with Spearman correlation, proportional odds logistic regression, and linear regression, adjusting for age, race, and sex.

RESULTS

Telomere length was significantly inversely correlated with age in patients with RA (ρ = -0.37, p < 0.001) and control subjects (ρ = -0.39, p = 0.001). Among patients with RA, for every interquartile range (IQR) decrease in telomere length (T/S ratio), the odds of higher coronary artery calcium score increased by 38% (95% CI: 4-60) after adjusting for age, race, and sex (p adjusted = 0.03). Telomere length was not associated with DAS28 (p adjusted = 0.17). Telomere length was not significantly different in patients with RA [median (IQR): 1.02 units (0.9-1.11)] compared to control subjects [1.05 units (0.95-1.17); p = 0.10].

CONCLUSION

Telomere length is inversely associated with coronary artery calcium score, independent of age, race, and sex in patients with RA.

Connective tissue diseases, multimorbidity and the ageing lung

Connective tissue diseases encompass a wide range of heterogeneous disorders characterised by immune-mediated chronic inflammation often leading to tissue damage, collagen deposition and possible loss of function of the target organ. Lung involvement is a common complication of connective tissue diseases. Depending on the underlying disease, various thoracic compartments can be involved but interstitial lung disease is a major contributor to morbidity and mortality. Interstitial lung disease, pulmonary hypertension or both are found most commonly in systemic sclerosis. In the elderly, the prevalence of connective tissue diseases continues to rise due to both longer life expectancy and more effective and better-tolerated treatments. In the geriatric population, connective tissue diseases are almost invariably accompanied by age-related comorbidities, and disease- and treatment-related complications, which contribute to the significant morbidity and mortality associated with these conditions, and complicate treatment decision-making. Connective tissue diseases in the elderly represent a growing concern for healthcare providers and an increasing burden of global health resources worldwide. A better understanding of the mechanisms involved in the regulation of the immune functions in the elderly and evidence-based guidelines specifically designed for this patient population are instrumental to improving the management of connective tissue diseases in elderly patients.

A Prospective Study Investigating Prediagnostic Leukocyte Telomere Length and Risk of Developing Rheumatoid Arthritis in Women

OBJECTIVE

To prospectively examine the association between leukocyte telomere length (LTL) and subsequent rheumatoid arthritis (RA) development in women.

METHODS

Using a case-control design nested within the prospective Nurses' Health Study (NHS), NHS II (NHSII), and Women's Health Study (WHS), each validated case of RA with a prediagnostic blood sample was matched to 3 controls by cohort, age, menopausal status, postmenopausal hormone therapy, and blood collection covariates. We measured telomere length in genomic DNA extracted from stored buffy coat samples using quantitative PCR. We used unconditional logistic regression to determine OR and 95% CI, and random-effects metaanalysis to combine study results.

RESULTS

In total, we analyzed 296 incident RA cases and 827 matched controls. Mean age of diagnosis among women who developed RA was 60.5 in NHS/NHSII and 61.3 in WHS. Metaanalysis demonstrated that longer prediagnostic LTL was associated with increased RA risk when women in the longest versus shortest LTL tertile were compared (OR 1.51, 95% CI 1.03-2.23, Pheterogeneity = 0.27). However, statistically significant between-study heterogeneity was observed for the intermediate tertile category (Pheterogeneity = 0.008). We did not observe heterogeneity by menopausal status, inflammatory cytokine levels, age at diagnosis, age at blood collection, body mass index, seropositivity, or HLA-DRβ1 shared epitope status.

CONCLUSION

Our results do not support an involvement for short LTL preceding RA development.

Ageing and the telomere connection: An intimate relationship with inflammation

Telomeres are the heterochromatic repeat regions at the ends of eukaryotic chromosomes, whose length is considered to be a determinant of biological ageing. Normal ageing itself is associated with telomere shortening. Here, critically short telomeres trigger senescence and eventually cell death. This shortening rate may be further increased by inflammation and oxidative stress and thus affect the ageing process. Apart from shortened or dysfunctional telomeres, cells undergoing senescence are also associated with hyperactivity of the transcription factor NF-κB and overexpression of inflammatory cytokines such as TNF-α, IL-6, and IFN-γ in circulating macrophages. Interestingly, telomerase, a reverse transcriptase that elongates telomeres, is involved in modulating NF-κB activity. Furthermore, inflammation and oxidative stress are implicated as pre-disease mechanisms for chronic diseases of ageing such as neurodegenerative diseases, cardiovascular disease, and cancer. To date, inflammation and telomere shortening have mostly been studied individually in terms of ageing and the associated disease phenotype. However, the interdependent nature of the two demands a more synergistic approach in understanding the ageing process itself and for developing new therapeutic approaches. In this review, we aim to summarize the intricate association between the various inflammatory molecules and telomeres that together contribute to the ageing process and related diseases.

Reactivity of rat bone marrow-derived macrophages to neurotransmitter stimulation in the context of collagen II-induced arthritis

Introduction

Numerous observations indicate that rheumatoid arthritis (RA) has a bone marrow component. In parallel, local synovial changes depend on neuronal components of the peripheral sympathetic nervous system. Here, we wanted to analyze whether collagen II-induced arthritis (CIA) has an impact on number, adhesion, apoptosis, and proliferation of the macrophage subset of bone marrow cells and how alterations in neurotransmitter microenvironment affect these properties.

Methods

Bone marrow-derived macrophages (BMMs) were isolated from Dark Agouti rats at different stages of CIA, and number, adhesion, caspase 3/7 activity, and proliferation were analyzed in the presence of acetylcholine (ACh), noradrenaline (NA), and vasoactive intestinal peptide (VIP).

Results

Opposed to enhanced CD11b⁺ (cluster of differentiation 11b-positive) and EMR1⁺ (epidermal growth factor-like module-containing mucin-like hormone receptor-like 1-positive) cells, characterizing the macrophage subset, in native bone marrow of rats with acute inflammatory arthritis, we found decreased numbers of CIA macrophages after enrichment and culture in comparison with healthy (control) animals. Adhesion studies revealed significantly reduced attachment to plastic in acute arthritis and collagen type I and fibronectin in chronic arthritis. Additionally, we found a strong reduction in proliferation of BMMs at CIA onset and in the chronic phase of CIA. Apoptosis remained unaffected. Neurotransmitter stimulation profoundly affected proliferation, adhesion, and apoptosis of BMMs from CIA and control rats, depending on disease time point. Cultured BMMs from CIA and control animals expressed neurotransmitter receptors for ACh, VIP and NA, but the expression profile seemed not to be affected by CIA.

Conclusions

Induction of CIA distinctly inhibits proliferation of BMMs in low- and non-inflammatory phases and reduces attachment to plastic at the acute inflammatory arthritis stage and adhesion to collagen I and fibronectin at the chronic stage. Influence of neurotransmitter stimulation on adhesion, apoptosis, and proliferation is altered by CIA depending on disease stage. We suggest an altered reactivity of BMMs to neurotransmitter stimulation caused by CIA and maybe also by aging.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0684-4) contains supplementary material, which is available to authorized users.

Association of Average Telomere Length with Body-Mass Index and Vitamin D Status in Juvenile Population with Type 1 Diabetes

Background

Type 1 diabetes (T1D) is an autoimmune chronic disease where hyperglycemia, increased risk of oxidative stress, advanced glycation end-products and other genetic and environmental factors lead to T1D complications. Shorter telomeres are associated with hyperglycemic levels and lower serum vitamin D levels.

Methods

Average telomere length (ATL) in whole blood DNA samples was assessed with qPCR method in 53 Slovenian T1D children/adolescents (median age 8.7 years, 1:1.3 male/female ratio). Body mass index standard deviation score (BMI-SDS), glycated haemoglobin and serum level of vitamin D metabolite (25-(OH)-D3) and the age at the onset of T1D were collected from the available medical documentation.

Results

Results indicate shorter ATL in subjects with higher BMI-SDS when compared to those with longer ATL (0.455 ± 0.438, −0.63 ± 0.295; p=0.049). Subjects with higher BMI-SDS had lower serum vitamin D levels when compared to those with lower BMI-SDS (40.66 ± 3.07 vs. 52.86 ± 4.85 nmol/L; p=0.045). Vitamin D serum levels did not significantly differ between subjects with longer/shorter ATL.

Conclusion

T1D children/adolescents with shorter ATL tend to have higher BMI-SDS. Lower serum vitamin D levels were associated with higher BMI-SDS, while associations between vitamin D serum levels, age at the onset of T1D, glycated haemoglobin and ATL were not observed. Additional studies with more participants are required to clarify the role of the telomere dynamics in T1D aetiology and development of complications.

Premature senescence of T-cell subsets in axial spondyloarthritis

OBJECTIVE

To investigate the possible occurrence of early thymic failure and premature senescence of naïve and memory T-cells in patients with axial spondyloarthritis (aSpA).

METHODS

Prospective, cross-sectional study of consecutive patients with aSpA (n=51), rheumatoid arthritis (RA, n=51) and healthy controls (HCs, n=50). Demographic, clinical and laboratory parameters were collected in all patients and we isolated naïve (CD45RA(+)) and memory (CD45RO(+)) CD4(+) and CD8(+) T-cell subsets by MACS technology. T-cell receptor rearrangement excision circle (TREC) and telomere length were measured by real-time PCR. We used TRECs as a surrogate for thymus function and telomere length as an indicator of cellular senescence. Telomerase activity was analysed with the Telomeric Repeat Amplification Protocols.

RESULTS

We observed a premature decline of thymic output in patients with aSpA and patients with RA compared with HCs as indicated by a reduction of TREC levels in naive T-cells (aSpA: age adjusted regression coefficient (regcoeff) for CD4(+)CD45RA(+) T-cells -2.566, p=0.023; RA regcoeff=-2.844, p=0.008). Telomere length of all CD4(+) and CD8(+) T-cell subsets was reduced in young patients with aSpA compared with HCs, whereas data for patients with RA were comparable with HCs. Telomerase activity was inversely correlated with telomere length in HCs (correlation coefficient (corcoeff)=-0.532, p<0.001) but not in patients with aSpA (corcoeff=-0.056, p=0.697) and RA (corcoeff=-0.003, p=0.982).

CONCLUSIONS

Our data indicate an age-inappropriate shrinkage of thymic output, an inappropriate shortening of telomeres in young patients with aSpA and an impaired telomerase enzyme in patients with aSpA and RA.

Stem cell therapies for systemic sclerosis

The presence of autoimmune diseases, including Systemic Sclerosis (SSc), suggest failure of the normal immune regulatory processes leading to activation and expansion of autoreactive effector immune cells. Recently, stem cell transplantation emerged as a novel rescue therapy for a variety of refractory autoimmune diseases. The therapeutic strategy involves the ablation of the aberrant self-reactive immune cells by chemotherapy and the regeneration of a new self-tolerant immune system formed by the transplanted stem cells. In the last few years, thousands of patients worldwide have received haematopoietic stem cell transplantation (HSCT), mostly autologous, as treatment for severe irreversible autoimmune diseases, with promising results. Here we review the results of published small series of SSc patients treated with allogeneic and autologous HSCT, as well as three randomized trials, exploring the safety and efficacy of autologous HSCT in SSc. Although the results are encouraging, nonetheless, the correct application of stem cell transplantation remains an area of active investigation. Results of larger randomized, double blind clinical trials, will certainly improve our knowledge of the appropriate clinical use of stem cell therapy in SSc patients.

T-cell aging in rheumatoid arthritis

PURPOSE OF REVIEW

With progressive age, the immune system and the propensity for abnormal immunity change fundamentally. Individuals greater than 50 years of age are not only more susceptible to infection and cancer, but also at higher risk for chronic inflammation and immune-mediated tissue damage. The process of immunosenescence is accelerated in rheumatoid arthritis (RA).

RECENT FINDINGS

Premature T-cell senescence occurs not only in RA, but also has been involved in morbidity and mortality of chronic HIV infection. Senescent cells acquire the 'senescence-associated secretory phenotype', which promotes and sustains tissue inflammation. Molecular mechanisms underlying T-cell aging are beginning to be understood. In addition to the contraction of T-cell diversity because of uneven clonal expansion, senescent T cells have defects in balancing cytoplasmic kinase and phosphatase activities, changing their activation thresholds. Also, leakiness in repairing DNA lesions and uncapped telomeres imposes genomic stress. Age-induced changes in the tissue microenvironment may alter the T-cell responses.

SUMMARY

Gain-of-function and loss-of-function in senescent T cells undermine protective immunity and create the conditions for chronic tissue inflammation, a combination typically encountered in RA. Genetic programs involved in T-cell signaling and DNA repair are of high interest in the search for underlying molecular defects.

Gap junction blockade induces apoptosis in human endometrial stromal cells

One of the most dynamic adult human tissues is the endometrium. Through coordinated, cyclical proliferation, differentiation, leukocyte recruitment, apoptosis, and desquamation, the uterine lining is expanded and shed monthly, unless pregnancy is established. Errors in these steps potentially cause endometrial dysfunction, abnormal uterine bleeding, failed embryonic implantation, infertility, or endometrial carcinoma. Our prior studies showed that gap junctions comprised of Gap junction alpha-1 (GJA1) protein, also known as connexin 43 (CX43), subunits are critical to endometrial stromal cell differentiation. The current studies were undertaken to explore the mechanism of endometrial dysfunction when gap junction intercellular communication (GJIC) is disrupted. Gap junction blockade by two distinct GJIC inhibitors, 18α-glycyrrhetinic acid (AGA) and octanol (OcOH), suppressed proliferation and induced apoptosis in endometrial stromal cells, as manifested by reduced biomarkers of cell viability, increased TUNEL staining, caspase-3 activation, sub-G1 chromosomal DNA complement, as well as shortened telomere length. Unexpectedly, we also observed that the chemical inhibitors blocked CX43 gene expression. Moreover, when endometrial stromal cells were induced to undergo hormonal decidualization, following a 7-day exposure to 10 nM 17β-estradiol + 100 nM progesterone + 0.5 mM dibutyryl cAMP, characteristic epithelioid changes in cell shape and secretion of prolactin were blunted in the presence of AGA or OcOH, recapitulating effects of RNA interference of CX43. Our findings indicate that endometrial stromal cell proliferation and maintenance of decidualized endometrial function are GJIC-dependent, and that disruption of gap junctions induces endometrial stromal cell apoptosis. These observations may have important implications for several common clinical endometrial pathologies.

Targets of immune regeneration in rheumatoid arthritis

Many of the aging-related morbidities, including cancer, cardiovascular disease, neurodegenerative disease, and infectious susceptibility, are linked to a decline in immune competence with a concomitant rise in proinflammatory immunity, placing the process of immune aging at the center of aging biology. Immune aging affects individuals older than 50 years and is accelerated in patients with the autoimmune disease rheumatoid arthritis. Immune aging results in a marked decline in protective immune responses and a parallel increase in tissue inflammatory responses. By studying immune cells in patients with rheumatoid arthritis, several of the molecular underpinnings of the immune aging process have been delineated, such as the loss of telomeres and inefficiencies in the repair of damaged DNA. Aging T cells display a series of abnormalities, including the unopposed up-regulation of cytoplasmic phosphatases and the loss of glycolytic competence, that alter their response to stimulating signals and undermine their longevity. Understanding the connection between accelerated immune aging and autoimmunity remains an area of active research. With increasing knowledge of the molecular pathways that cause immunosenescence, therapeutic interventions can be designed to slow or halt the seemingly inevitable deterioration of protective immunity with aging.

Rheumatoid arthritis and cardiovascular disease

BACKGROUND

Rheumatic disease and heart disease share common underpinnings involving inflammation. The high levels of inflammation that characterize rheumatic diseases provide a "natural experiment" to help elucidate the mechanisms by which inflammation accelerates heart disease. Rheumatoid arthritis (RA) is the most common of the rheumatic diseases and has the best studied relationships with heart disease.

METHODS

A review of current literature on heart disease and RA was conducted.

RESULTS

Patients with RA have an increased risk of developing heart disease that is not fully explained by traditional cardiovascular risk factors. Therapies used to treat RA may also affect the development of heart disease; by suppressing inflammation, they may also reduce the risk of heart disease. However, their other effects, as in the case of steroids, may increase heart disease risk.

CONCLUSIONS

Investigations of the innate and adaptive immune responses occurring in RA may delineate novel mechanisms in the pathogenesis of heart disease and help identify novel therapeutic targets for the prevention and treatment of heart disease.

The influence of ageing on the development and management of rheumatoid arthritis

The population of elderly individuals with rheumatoid arthritis (RA) is expanding, due mainly to increasing life expectancy. A variety of theories have been proposed to explain the ageing process, including accumulation of DNA damage and resultant changes in biological processes. Such changes can influence the development and/or course of disease. Furthermore, alterations in biological function determine the biological age-as opposed to chronological age-of an individual, which strongly influences their ability to cope with disease. Moreover, comorbidities are more frequent in elderly individuals. Together, these factors complicate treatment of disease and necessitate careful patient management. Indeed, although evidence from clinical trials suggests that DMARDs and biologic agents have good efficacy and are well tolerated in elderly patients with RA, such individuals are often undertreated and inadequately managed. Unfortunately, insufficient data are available for the development of evidence-based guidelines for this population, as elderly patients are often excluded from clinical trials owing to age restrictions or comorbidities. Thus, additional clinical studies in elderly patients are warranted, with treatment regimens tailored according to vitality or frailty parameters. This Review focuses on the pathophysiological aspects of ageing and their implications for the management of RA in elderly patients.

The janus head of T cell aging - autoimmunity and immunodeficiency

Immune aging is best known for its immune defects that increase susceptibility to infections and reduce adaptive immune responses to vaccination. In parallel, the aged immune system is prone to autoimmune responses and many autoimmune diseases increase in incidence with age or are even preferentially encountered in the elderly. Why an immune system that suboptimally responds to exogenous antigen fails to maintain tolerance to self-antigens appears to be perplexing. In this review, we will discuss age-associated deviations in the immune repertoire and the regulation of signaling pathways that may shed light on this conundrum.

Understanding immunosenescence to improve responses to vaccines

In the older adult, the benefits of vaccination to prevent infectious disease are limited, mainly because of the adaptive immune system's inability to generate protective immunity. The age-dependent decrease in immunological competence, often referred to as 'immunosenescence', results from the progressive deterioration of innate and adaptive immune responses. Most insights into mechanisms of immunological aging have been derived from studies of mouse models. In this Review, we explore how well such models are applicable to understanding the aging process throughout the 80-100 years of human life and discuss recent advances in identifying and characterizing the mechanisms that underlie age-associated defective adaptive immunity in humans.

Anaemia may add information to standardised disease activity assessment to predict radiographic damage in rheumatoid arthritis: a prospective cohort study

OBJECTIVE

Anaemia in rheumatoid arthritis (RA) is prototypical of the chronic disease type and is often neglected in clinical practice. We studied anaemia in relation to disease activity, medications and radiographic progression.

METHODS

Data were collected between 1996 and 2007 over a mean follow-up of 2.2 years. Anaemia was defined according to WHO (♀ haemoglobin<12 g/dl, ♂: haemoglobin<13 g/dl), or alternative criteria. Anaemia prevalence was studied in relation to disease parameters and pharmacological therapy. Radiographic progression was analysed in 9731 radiograph sets from 2681 patients in crude longitudinal regression models and after adjusting for potential confounding factors, including the clinical disease activity score with the 28-joint count for tender and swollen joints and erythrocyte sedimentation rate (DAS28ESR) or the clinical disease activity index (cDAI), synthetic antirheumatic drugs and antitumour necrosis factor (TNF) therapy.

RESULTS

Anaemia prevalence decreased from more than 24% in years before 2001 to 15% in 2007. Erosions progressed significantly faster in patients with anaemia (p<0.001). Adjusted models showed these effects independently of clinical disease activity and other indicators of disease severity. Radiographic damage progression rates were increasing with severity of anaemia, suggesting a 'dose-response effect'. The effect of anaemia on damage progression was maintained in subgroups of patients treated with TNF blockade or corticosteroids, and without non-selective nonsteroidal anti-inflammatory drugs (NSAIDs).

CONCLUSIONS

Anaemia in RA appears to capture disease processes that remain unmeasured by established disease activity measures in patients with or without TNF blockade, and may help to identify patients with more rapid erosive disease.

Stem cells in autoimmune diseases: Implications for pathogenesis and future trends in therapy

In this review we report the recent progresses, available in the literature, concerning the biology and the potential therapeutic role of both mesenchymal stem cells (MSCs) and hematopoietic stem cells in autoimmune diseases. Mesenchymal stem cells (MSCs) are responsible for the normal turnover and maintenance of adult mesenchymal tissues and their pleiotropic nature allows them to sense and respond to an event in the local environment, be it injury or inflammation. Recently, MSCs have been shown to have immune-modulatory properties and immunosuppressive capacities, acting on different immune cells both in vitro and in vivo, in addition to an immunologically privileged phenotype. Moreover, several works suggest that MSCs are defective in autoimmune diseases. These aspects are now considered the most intriguing aspect of their biology, introducing the possibility that these cells might be used as effective therapy in autoimmune diseases. Autoimmune diseases represent a failure of normal immune regulatory processes as they are characterized by activation and expansion of immune cell subsets in response to non-pathogenic stimuli. As autoimmune diseases can be transferred, or alternatively, cured, by stem cell transplantation, a defect in the hemopoietic stem cell as a cause of autoimmune diseases may be postulated. The rationale for autologous hematopoietic stem cell transplantation (HSCT) in autoimmune diseases is the ablation of an aberrant or self-reactive immune system by chemotherapy and regeneration of a new and hopefully self-tolerant immune system from hematopoietic stem cells. In the past 15years, more than 1500 patients worldwide have received HSCT, mostly autologous, as treatment for a severe autoimmune disease and the majority were affected by multiple sclerosis, systemic sclerosis, systemic lupus erythematosus, rheumatoid arthritis, juvenile idiopathic arthritis and idiopathic cytopenic purpura.