Analysis of serum immune markers in seropositive and seronegative rheumatoid arthritis and in high-risk seropositive arthralgia patients

Presence of autoantibodies precedes development of seropositive rheumatoid arthritis (SP RA) and seropositive arthralgia patients (SAP) are at risk of developing RA. The aims of the study are to identify additional serum immune markers discriminating between SP and seronegative (SN) RA, and markers identifying high-risk SAP. Sera from SAP (n = 27), SP RA (n = 22), SN RA (n = 11) and healthy controls (n = 20) were analyzed using the Human Cytokine 25-Plex Panel. Selected markers were validated in independent cohorts of SP RA (n = 35) and SN RA (n = 12) patients. Eleven of 27 SAP developed RA within 8 months (median follow-up time, range 1-32 months), and their baseline serum markers were compared to 16 non-progressing SAP. SAP and SP RA patients showed a marked overlap in their systemic immune profiles, while SN RA showed a distinct immune profile. Three of 4 markers discriminating between SP and SN RA (IL-1 beta, IL-15 and Eotaxin, but not CCL5) were similarly modulated in independent cohorts. SAP progressing to RA showed trends for increases in IL-5, MIP-1 beta, IL-1RA and IL-12 compared to non-progressing SAP. ROC analysis showed that serum IL-5 most accurately discriminated between the two SAP groups (AUC > 0.8), suggesting that baseline IL-5 levels may aid the identification of high-risk SAP

Expression of Lectin-Like Transcript 1, the Ligand for CD161, in Rheumatoid Arthritis

Precursor Th17 lineage cells expressing CD161 are implicated in Rheumatoid Arthritis (RA) pathogenesis. CD4+CD161+ T-cells accumulate in RA joints and may acquire a non classical Th1 phenotype. The endogenous ligand for CD161 is lectin-like transcript 1 (LLT1). CD161/LLT1 ligation may co-stimulate T-cell IFN-γ production. We investigated the presence and identity of LLT1-expressing cells in RA synovial fluid (SF) and synovial tissue (ST). We also assessed levels of soluble LLT1 (sLLT1) in different phases of RA development.Paired samples of peripheral blood mononuclear cells (MC) and SFMC (n = 14), digested ST cells (n = 4) and ST paraffin sections (n = 6) from late-stage RA were analyzed for LLT1 expression by flow cytometry and immunohistochemistry. sLLT1 was measured using a sandwich ELISA. Sera and SF from late-stage RA (n = 26), recently diagnosed RA patients (n = 39), seropositive arthralgia patients (SAP, n = 31), spondyloarthropathy patients (SpA, n = 26) and healthy controls (HC, n = 31) were assayed.In RA SF, LLT1 was expressed by a small proportion of monocytes. In RA ST, LLT1-expressing cells were detected in the lining, sublining layer and in areas with infiltrates. The LLT1 staining pattern overlapped with the CD68 staining pattern. FACS analysis of digested ST confirmed LLT1 expression by CD68+ cells. Elevated systemic sLLT1 was found in all patient groups.In RA joints, LLT1 is expressed by cells of the monocyte/macrophage lineage. Serum levels of sLLT1 were increased in all patient groups (patients with early- and late-stage RA, seropositive arthralgia and spondyloarthropathy) when compared to healthy subjects

Systemic immune markers characterizing early stages of rheumatoid arthritis

Rheumatoid arthritis is a chronic autoimmune disease occurring in ~1% of the world population. The main feature of the disease is ongoing joint inflammation, caused by immune cells and their soluble factors, leading to irreversible bone erosions and cartilage damage. Early treatment can halt progression of the disease and development of irreversible damage. Early recognition is therefore very important. Present research is geared at recognizing development of RA as early as possible by identifying high risk individuals before definite clinical symptoms of RA develop. Interestingly, although the joints are the target of the immune system in RA, it is a systemic disease which may start elsewhere in the body. This notion is supported by the emergence of antibodies against self antigens (autoantibodies directed at citrullinated proteins (ACPA) and rheumatoid factor (RF)) and an increase of inflammatory markers in the blood, which may occur years before RA diagnosis. Several studies have shown that seropositive (ACPA and/or RF positive) arthralgia patients are at risk to develop RA. Thus, in order to prevent RA progression, it is important to identify specific alterations within the immune system that are involved in the switch from the high-risk state to full-blown disease. Our general aim was to define peripheral immune alterations in seropositive arthralgia patients and in newly diagnosed RA patients. This approach allowed the identification of systemic immune markers that may be involved in disease development. In addition, we identified immune alterations which may contribute to the worsening of joint inflammation in long-standing RA patients

Chronic autoimmune-mediated inflammation:a senescent immune response to injury

<p>The increasing prevalence of chronic autoimmune-mediated inflammatory diseases (AIMIDs) in ageing western societies is a major challenge for the drug development industry. The current high medical need for more-effective treatments is at least in part caused by our limited understanding of the mechanisms that drive chronic inflammation. Here, we postulate a role for immunosenescence in the progression of acute to chronic inflammation via a dysregulated response to primary injury at the level of the damaged target organ. A corollary to this notion is that treatment of acute versus chronic phases of disease might require differential targeting strategies.</p>

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

Altered Natural Killer Cell Subsets in Seropositive Arthralgia and Early Rheumatoid Arthritis Are Associated with Autoantibody Status

Objective. The role of natural killer (NK) cells in the immunopathogenesis of rheumatoid arthritis (RA) is unclear. Therefore, numerical and functional alterations of CD56(dim) and CD56(bright) NK cells in the early stages of RA development were studied. Methods. Whole blood samples from newly diagnosed, treatment-naive, seropositive (SP) and seronegative (SN) patients with RA (SP RA, n = 45 and SN RA, n = 12), patients with SP arthralgia (n = 30), and healthy controls (HC, n = 41) were assessed for numbers and frequencies of T cells, B cells, and NK cells. SP status was defined as positive for anticyclic citrullinated peptide antibodies (anti-CCP) and/or rheumatoid factor (RF). Peripheral blood mononuclear cells were used for further analysis of NK cell phenotype and function. Results. Total NK cell numbers were decreased in SP RA and SP arthralgia but not in SN RA. Also, NK cells from SP RA showed a decreased potency for interferon-gamma (IFN-gamma) production. A selective decrease of CD56(dim), but not CD56(bright), NK cells in SP RA and SP arthralgia was observed. This prompted investigation of CD16 (Fc gamma RIIIa) triggering in NK cell apoptosis and cytokine expression. In vitro, CD16 triggering induced apoptosis of CD56(dim) but not CD56(bright) NK cells from HC. This apoptosis was augmented by adding interleukin 2 (IL-2). Also, CD16 triggering in the presence of IL-2 stimulated IFN-gamma and tumor necrosis factor-alpha expression by CD56(dim) NK cells. Conclusion. The decline of CD56(dim) NK cells in SP arthralgia and SP RA and the in vitro apoptosis of CD56(dim) NK cells upon CD16 triggering suggest a functional role of immunoglobulin G-containing autoantibody (anti-CCP and/or RF)-immune complexes in this process. Moreover, CD16-triggered cytokine production by CD56(dim) NK cells may contribute to systemic inflammation as seen in SP arthralgia and SP RA

sLLT1 is increased in the serum of SAP, early and late-stage RA and SpA patients.

<p>A) Sera from HC (n = 31), SAP (n = 31), early RA patients (n = 39) and late RA patients (n = 26) and SpA patients (n = 26) were used to quantify the levels of soluble LLT1 using sandwich ELISA. Horizontal lines represent the mean value. Unpaired t test was used. B) Paired SF samples were used to compare the level of soluble LLT1 in PB and SF of long-standing RA (n = 26; Wilcoxon matched pairs test). Statistical significance is indicated as * for p <0.05, ** for p <0.001, and *** for p <0.0001. Rabbit polyclonal anti-LLT1 antibodies provided with a commercially available ELISA (MyBiosource) were used.</p