Long-term persistent accumulation of CD8+ T cells in synovial fluid of rheumatoid arthritis

Progression of pre-rheumatoid arthritis to clinical disease of joints: Potential role of mesenchymal stem cells

Rheumatoid arthritis (RA) related autoimmunity is developed at mucosal sites due to the interplay between genetic risk factors and environmental triggers. The pre-RA phase that leads to anti-citrullinated protein antibodies, rheumatoid factor, and other autoantibodies spread in the systemic circulation may not affect articular tissue for years until a mysterious second hit triggers the localization of RA-related autoimmunity in joints. Several players in the joint microenvironment mediate the synovial innate and adaptive immunological processes, eventually leading to clinical synovitis. There still exists a gap in the early phase of RA pathogenesis, i.e., the progression of diseases from the systemic circulation to joints. The lack of better understanding of these events results in the inability to answer questions about why only after a certain point of time the disease appears in joints and why in some cases, it simply remains latent and doesn't affect joints at all. In the current review, we focused on the immunomodulatory and regenerative role of mesenchymal stem cells and associated exosomes in RA pathology. We also highlighted the age-related dysregulations in activities of mesenchymal stem cells and how that might trigger homing of systemic autoimmunity to joints.

Intersection Between Large Granular Lymphocyte Leukemia and Rheumatoid Arthritis

Large granular lymphocyte (LGL) leukemia, a rare hematologic malignancy, has long been associated with rheumatoid arthritis (RA), and the diseases share numerous common features. This review aims to outline the parallels and comparisons between the diseases as well as discuss the potential mechanisms for the relationship between LGL leukemia and RA. RA alone and in conjunction with LGL leukemia exhibits cytotoxic T-cell (CTL) expansions, HLA-DR4 enrichment, RA-associated autoantibodies, female bias, and unknown antigen specificity of associated T-cell expansions. Three possible mechanistic links between the pathogenesis of LGL leukemia and RA have been proposed, including LGL leukemia a) as a result of longstanding RA, b) as a consequence of RA treatment, or c) as a driver of RA. Several lines of evidence point towards LGL as a driver of RA. CTL involvement in RA pathogenesis is evidenced by citrullination and granzyme B cleavage that modifies the repertoire of self-protein antigens in target cells, particularly neutrophils, killed by the CTLs. Further investigations of the relationship between LGL leukemia and RA are warranted to better understand causal pathways and target antigens in order to improve the mechanistic understanding and to devise targeted therapeutic approaches for both disorders.

Measuring the T-cell down-regulation of TCR-zeta, ZAP-70 and CD28 in arthritis patients: An old tool for new biomarkers

Low T-cell receptor (TCR)/CD28 signaling lymphocytes are expanded in arthritis. We asked whether the down-expression of TCR-related molecules correlates with specific arthritis characteristics and if it has clinical implications. TCR-ZETA, ZAP-70 and CD28 expression was measured by flow cytometry in synovial fluid (SF) and peripheral blood (PB)-derived T cells. In PB, ZETA-downregulation in CD4⁺ CD28⁺ and consequent CD4⁺ CD28lowZETAlow cell expansion correlate with CRP elevation, leukocyte recruitment into SF and, primarily, disease activity (DAS). In some patients, ZETA-downregulation extends to CD8⁺ CD28null and/or CD8⁺ CD28⁺ cells, and this correlates with enhanced leukocyte recruitment, multiple joint involvement, and disability index (HAQ). ZETA-downregulation in CD4⁺ CD28⁺ may also lead to CD4⁺ CD28⁺ ZETAnull cell expansion, which strongly correlates with HAQ. In SF, ZETA-downregulation in CD8⁺ CD28null and consequent CD8⁺ CD28nullZETAlow/null cell expansion correlate with CRP elevation and neutrophilic influx into SF, whereas ZAP-downregulation in CD8⁺ CD28⁺ and consequent CD8⁺ CD28lowZAPlow cell expansion strongly correlate with HAQ and DAS. ZETA-downregulation is preponderant in SF of seronegative arthritides, with seronegative rheumatoid arthritis showing significant down-regulation in CD8⁺ CD28null, and non-rheumatoid arthritides showing significant down-regulation in CD4⁺ CD28⁺ . Altogether, we identified new molecular and cellular biomarkers of arthritis-related T-cell inflammation, useful for assessing arthritis activity, predicting polyarticular progression and functional impairment, characterizing seronegative arthritides, and possibly tailoring immunotherapies.

Improved flow cytometric assessment reveals distinct microvesicle (cell-derived microparticle) signatures in joint diseases

Introduction

Microvesicles (MVs), earlier referred to as microparticles, represent a major type of extracellular vesicles currently considered as novel biomarkers in various clinical settings such as autoimmune disorders. However, the analysis of MVs in body fluids has not been fully standardized yet, and there are numerous pitfalls that hinder the correct assessment of these structures.

Methods

In this study, we analyzed synovial fluid (SF) samples of patients with osteoarthritis (OA), rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA). To assess factors that may confound MV detection in joint diseases, we used electron microscopy (EM), Nanoparticle Tracking Analysis (NTA) and mass spectrometry (MS). For flow cytometry, a method commonly used for phenotyping and enumeration of MVs, we combined recent advances in the field, and used a novel approach of differential detergent lysis for the exclusion of MV-mimicking non-vesicular signals.

Results

EM and NTA showed that substantial amounts of particles other than MVs were present in SF samples. Beyond known MV-associated proteins, MS analysis also revealed abundant plasma- and immune complex-related proteins in MV preparations. Applying improved flow cytometric analysis, we demonstrate for the first time that CD3⁺ and CD8⁺ T-cell derived SF MVs are highly elevated in patients with RA compared to OA patients (p = 0.027 and p = 0.009, respectively, after Bonferroni corrections). In JIA, we identified reduced numbers of B cell-derived MVs (p = 0.009, after Bonferroni correction).

Conclusions

Our results suggest that improved flow cytometric assessment of MVs facilitates the detection of previously unrecognized disease-associated vesicular signatures.

The spectrum of large granular lymphocyte leukemia and Felty's syndrome

PURPOSE OF REVIEW

Patients with chronic large granular lymphocyte (LGL) leukemia often have rheumatoid arthritis (RA), neutropenia and splenomegaly, thereby resembling the manifestations observed in patients with Felty's syndrome, which is a rare complication of RA characterized by neutropenia and splenomegaly. Both entities have similar clinical and laboratory presentation, as well as a common genetic determinant, HLA-DR4, indicating they may be part of the same disease spectrum. This review paper seeks to discuss the underlying pathogenesis and therapeutic algorithm of RA, neutropenia and splenomegaly in the spectrum of LGL leukemia and Felty's syndrome.

RECENT FINDINGS

We hypothesize that there may be a common pathogenic mechanism between LGL leukemia and typical Felty's syndrome. Phenotypic and functional data have strongly suggested that CD3 LGL leukemia is antigen-activated. Aberrations in the T-cell repertoire with the emergence of oligoclonal/clonal lymphoid populations have been found to play a pivotal role in pathogenesis of RA. The biologic properties of the pivotal T cell involved in RA pathogenesis are remarkably similar to those in leukemic LGL.

SUMMARY

RA-associated T-cell LGL leukemia and articular manifestations of typical Felty's syndrome are not distinguishable. A common pathogenetic link between LGL leukemia and RA is proposed.

Disturbances in B- and T-cell homeostasis in rheumatoid arthritis: suggested relationships with antigen-driven immune responses

Naïve and memory B- and T-cell subsets were examined with three-color flow cytometry in the peripheral blood of patients with rheumatoid arthritis (RA) in comparison with healthy controls, and their association with disease duration, activity and autoantibodies was investigated in order to reveal potential imprints of antigen-specific immune response in RA. The B-cell population consisted of significantly less naïve (58.1+/-3.9% versus 68.7+/-3.7%; p=0.04), and more IgD-/CD27+ memory B cells (19.6+/-2.1% versus 13.7+/-2.1%; p=0.04) compared to healthy subjects. In addition, strong correlation was demonstrated between disease duration and the percentage of memory B cells (p<0.0001). Increased CD8+ terminally differentiated effector memory/central memory T-cell ratio (1.35+/-0.35 versus 0.84+/-0.24) was also detected in RA patients compared with controls, which also correlated with the duration of RA (p=0.005). The frequency of memory B cells and CD8+ effector memory T cells correlated with the proportion of CD4+ effector memory lymphocytes, suggesting cooperation between immune cells. Our results reflect disturbances in B- and T-cell homeostasis characterized by the accumulation of memory B cells and a shift towards CD8+ terminally differentiated effector memory T cells in RA, suggesting ongoing, antigen-driven immune response and accelerated differentiation of B and T lymphocytes into effector cells.

Decreased effector memory CD45RA+ CD62L- CD8+ T cells and increased central memory CD45RA- CD62L+ CD8+ T cells in peripheral blood of rheumatoid arthritis patients

Although a role for CD8+ T cells in the pathogenesis of rheumatoid arthritis (RA) has been suggested, the precise nature of their involvement is not fully understood. In the present study we examined the central and effector memory phenotypes of CD4+ and CD8+ T cells in the peripheral blood of patients with RA and systemic lupus erythematosus. Terminally differentiated effector memory CD45RA+CD62L-CD8+ T cells were significantly decreased in RA patients, whereas the central memory CD45RA-CD62L+ CD8+ T-cell population was increased as compared with levels in healthy control individuals. Naïve and preterminally differentiated effector memory CD45RA-CD62L- CD8+ T cells did not differ between RA patients and control individuals. The CD45RA-CD62L+ central memory CD4+ T-cell subpopulation was increased in RA patients, whereas the naïve and effector memory phenotype of CD4+ T cells did not differ between RA patients and control individuals. In patients with systemic lupus erythematosus the distribution of naïve/memory CD4+ and CD8+ T cells did not differ from that in age- and sex-matched control individuals. These findings show that peripheral blood CD8+ T cells from RA patients exhibit a skewed maturation phenotype that suggests a perturbation in the homeostasis of these cells. The central memory CD45RA-CD62L+ CD4+ and CD8+ T-cell numbers were increased in RA, suggesting an accelerated maturation of naïve T cells. The decreased numbers of terminally differentiated CD45RA+CD62L- effector memory CD8+ T cells in peripheral blood of RA patients may reflect increased apoptosis of these cells or enhanced migration of these cells to sites of inflammation, which may play a role in the pathogenesis of RA.

T-cell clonotypes specific for Dermatophagoides pteronyssinus in the skin lesions of patients with atopic dermatitis

T-cell mediated immune response, toward the house dust mite (HDM) antigens in particular, has been reported to be involved in the pathogenesis of atopic dermatitis (AD). On the other hand, studies on the infiltrating lymphocytes in the skin lesion of AD revealed oligoclonal T-cell accumulation. However, it is not clear exactly what antigen(s) the accumulating T cells are exactly recognize in situ. Therefore, this study attempted to determine whether or not the clonally expanded T-cell clones in the diseased skin recognize HDM. Specifically, peripheral blood mononuclear cells (PBMC) obtained from six patients with AD, who revealed high titers of anti-HDM IgE, were stimulated with HDM antigens purified from Dermatophagoides pteronyssinus (Dp). T-cell clonotypes expanded by the stimulation were then identified by the analysis of their T-cell receptor (TCR) B-gene sequences using a combination of the reverse transcription-polymerase chain reaction and subsequent single strand conformation polymorphism separation. The Dp-responding T-cell clonotypes were compared with those that accumulated in the AD skin lesion in vivo. Nucleotide sequences of the TCR were also determined. As a result, the Dp stimulation induced oligoclonal T-cell expansion from the originally heterogeneous peripheral T-cell population of AD patients. However, only a small part of the Dp-reacting T-cell clonotypes detected in PBMC was identical to those accumulated in the AD skin lesion in vivo, and vice versa. This indicates that the frequency of the clonal expansion of Dp-specific T-cell clonotypes in the skin lesion of AD would be rather limited.

Disappearance of clonally expanded T cells after allogeneic leukocyte immunotherapy in peripheral blood of patients with habitual abortion

Allogeneic leukocyte immunotherapy is often used to improve fertility of patients with habitual abortion (HA), which probably acts through immune-mediated mechanisms. However, the involvement of T cells is not clear. This study examined the effect of allogeneic immunotherapy on T cells of patients with HA. Peripheral blood mononuclear cells were obtained from 5 healthy women and 14 women with HA. RNA was isolated from mononuclear blood cells. Reverse transcription-polymerase chain reaction (RT-PCR), followed by single-strand conformational polymorphism (SSCP) were used to analyze the gene segments of T-cell receptor beta chain (TCRbetaV) variable regions. Oligoclonal accumulation of T cells was identified in peripheral blood of nonpregnant patients with a history of HA. It was also revealed, however, that immunostimulation reduced the number of accumulating T-cell clones (p = 0.0004). The results, together with the clinical effectiveness of immunotherapy, suggest that accumulation of T-cell clonotypes, which probably resulted from antigenic stimulation, is involved in the pathogenesis of HA.

Gene-transferred oligoclonal T cells predominantly persist in peripheral blood from an adenosine deaminase-deficient patient during gene therapy

Adenosine deaminase (ADA) deficiency is the primary cause of severe combined immunodeficiency disease and has become a focus for developing innovative approaches to gene therapy. We previously described successful treatment of a Japanese ADA-deficient patient by periodic infusions of genetically modified autologous T lymphocytes transduced with a retroviral vector containing human ADA cDNA. In order to investigate whether polyclonality was restored by the gene therapy and whether the gene-transduced T lymphocytes persisted in the peripheral blood of the patient, we analyzed the T cell clonotype using a T cell receptor-specific RT-PCR/SSCP method. Oligoclonal T cell expansion was observed in every Vbeta family, and the expanded T cell clones were stable throughout the periodic gene therapy. Some of these T cell clones are likely carrying the vector, since they were identical to the clones selected by G418 resistance. Therefore, although it is uncertain when oligoclonal T cells started to expand and what percentage of the oligoclones carries the vector, the peripheral blood of the patient administered the gene therapy included oligoclonal T cells, some of which were identical to the ADA-gene-transduced clones.

Effect of IL15 on T cell clonality in vitro and in the synovial fluid of patients with rheumatoid arthritis

OBJECTIVE

Recent studies have suggested that interleukin (IL) 15 induces T cell accumulation in synovial lesions of rheumatoid arthritis (RA). This study aimed at determining whether this cytokine could explain in vivo T cell clonality in RA.

METHODS

Peripheral blood mononuclear cells (PBMC) from patients with RA were stimulated in vitro with IL15 or IL2. After isolation of mRNA from stimulated cells and synovial T cells, genes coding the V-D(N)-J (CDR3) region of T cell receptor beta chains were amplified by a reverse transcriptase polymerase chain reaction. A single strand conformation polymorphism analysis was used to detect the clonotype(s) of accumulating T cells. Nucleotide and amino acid sequencing was also performed.

RESULTS

Stimulation of PBMC with IL15 resulted in oligoclonal expansion of T cells. However, IL15 induced clones from PBMC were mostly different from the dominantly expanding T cell clones in synovial fluid. Furthermore, IL15 and IL2 responding clones were only partially identical.

CONCLUSIONS

Although IL15 results in clonal accumulation of T cells, T cell clonality in rheumatoid joints could not be explained by the effect of IL15 alone. The results indicated the requirement of other factor(s), in addition to IL15, in the pathological process affecting RA joints. The results also suggested different responses by each T cell clone to IL15 or IL2.