MicroRNA-155—at the critical interface of innate and adaptive immunity in arthritis

MicroRNAs (miRNAs) are small non-coding RNAs that fine-tune the cell response to a changing environment by modulating the cell transcriptome. MiR-155 is a multifunctional miRNA enriched in cells of the immune system and is indispensable for the immune response. However, when deregulated, miR-155 contributes to the development of chronic inflammation, autoimmunity, cancer and fibrosis. Herein, we review the evidence for the pathogenic role of miR-155 in driving aberrant activation of the immune system in Rheumatoid Arthritis, and its potential as a disease biomarker and therapeutic target

Thymosin β4 and β10 in Sjögren's syndrome: Saliva proteomics and minor salivary glands expression

Background: In the present study, we investigated whether thymosin β (Tβ) in saliva and in minor salivary glands is differentially expressed in patients with primary Sjögren's syndrome (pSS) and patients with autoimmune diseases (systemic sclerosis [SSc], systemic lupus erythematosus [SLE], and rheumatoid arthritis [RA], with and without sicca syndrome [ss]). Methods: Saliva specimens of nine patients with pSS, seven with ss/SSc, seven with ss/SLE, seven with ss/RA, seven with SSc, seven with SLE, and seven with RA, as well as ten healthy subjects, were analyzed using a high-performance liquid chromatograph coupled with a mass spectrometer equipped with an electrospray ionization source to investigate the presence and levels of Tβ4, Tβ4 sulfoxide, and Tβ10. Immunostaining for Tβ4 and Tβ10 was performed on minor salivary glands of patients with pSS and ss. Results: Tβ4 levels were statistically higher in patients with pSS with respect to the other subgroups. Tβ10 was detectable in 66.7 % of patients with pSS and in 42.8 % of those with ss/SSc, while Tβ4 sulfoxide was detectable in 44.4 % of patients with pSS and in 42.9 % of those with ss/SSc. Tβ10 and Tβ4 sulfoxide were not detectable in patients without associated ss and in healthy control subjects. Regarding thymosin immunostaining, all patients had immunoreactivity for Tβ10, and a comparable distribution pattern in the four different subgroups of patients was observed. Tβ4 immunoreactivity was present in patients with ss/SSc and those with ss/SLE, while it was completely absent in patients with pSS and those with ss/RA. Conclusions: Our data show that higher salivary Tβ expression characterizes patients with pSS, while Tβ4 sulfoxide and Tβ10 salivary expression was selectively present in patients with sicca symptoms. Moreover, at the immunohistochemical level in patients with pSS, minor salivary glands showed a peculiar pattern characterized by immunostaining for Tβ10 in acinar cells in the absence of any reactivity for Tβ4. These findings, taken together, suggest a different role for Tβ4 and Tβ10 in patients with pSS who have ss and other autoimmune disease

MicroRNA-155 influences B-cell function through PU.1 in rheumatoid arthritis

MicroRNA-155 (miR-155) is an important regulator of B cells in mice. B cells have a critical role in the pathogenesis of rheumatoid arthritis (RA). Here we show that miR-155 is highly expressed in peripheral blood B cells from RA patients compared with healthy individuals, particularly in the IgD-CD27- memory B-cell population in ACPA+ RA. MiR-155 is highly expressed in RA B cells from patients with synovial tissue containing ectopic germinal centres compared with diffuse synovial tissue. MiR-155 expression is associated reciprocally with lower expression of PU.1 at B-cell level in the synovial compartment. Stimulation of healthy donor B cells with CD40L, anti-IgM, IL-21, CpG, IFN-α, IL-6 or BAFF induces miR-155 and decreases PU.1 expression. Finally, inhibition of endogenous miR-155 in B cells of RA patients restores PU.1 and reduces production of antibodies. Our data suggest that miR-155 is an important regulator of B-cell activation in RA

Citrullination: the loss of tolerance and development of autoimmunity in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial inflammation and pannus formation, which can lead to severe destruction of cartilage and bone. Several self proteins have been suggested to be disease-driving autoantigens. Moreover the presence of autoantibodies to citrullinated proteins in sera of patients with RA enhances the strength of this hypothesis. Proteins are encoded by a limited number of genes in our genome. Post-translational modifications such as phosphorylation, glycosylation and citrullination can increase the morphological and the functional diversity of the proteome

analysis of the kinetic of expression of tristetraprolin and hur by rheumatoid arthritis patients pheripheral blood mononuclear cells stimulated with lipopolysaccharide

Objective. Given the role of TNF-α in Rheumatoid Arthritis (RA) we decided to define the characteristics of the TNF- α synthesis by peripheral blood mononuclear cells (PBMNCs) obtained from active-aggressive RA patients giving a particular attention to the modulation of the expression of two fundamental proteins in TNF-α mRNA stability regulation, Tristetraprolin (TTP) and HuR. Methods. 11 RA patients with active disease were enrolled in the study before their entry in 2 double blind protocols: Infliximab versus MTX and Etanercept versus MTX. 9 healthy blood donors were taken as controls. PBMNCs obtained by Ficoll centrifugation and plastic adherence were stimulated with lipopolysaccharide (LPS) and TNF-α was measured in the supernatant during 8 hours by ELISA. At each time point the cells were harvested and analysed for TNF- α, TTP and HuR mRNA expression by semi-quantitative PCR. Results. MNCs TNF-α secretion after LPS stimulation did not differ significantly between RA and control subjects, even if a tendency towards a more prompt response was observed in the patients. More importantly only the DMARDs responsive patients (DAS <3.7 at the 6th month, with a minimal reduction of 1.2 points) disclosed precociously (at the first month) a significant change in the profile of TNF-α secretion and maintained it until the 6th month. The "normalization" of the synthetic behaviour was accompanied by the resetting in the regulation of the expression of the TTP, that appeared significantly different in the patients before and after therapy. Conclusions. Independently from the type of therapy, responsive patients demonstrate a rapid change in the cellular biology at the systemic level that might drive the resolution of the phlogistic process at the synovial level

JAK inhibition by methotrexate (and csDMARDs) may explain clinical efficacy as monotherapy and combination therapy

Methotrexate (MTX) is recognized as the anchor drug in the algorithm treating chronic arthritis (RA, psoriatic arthritis), as well as a steroid sparing agent in other inflammatory conditions (polymyalgia rheumatica, vasculitis, scleroderma). Its main mechanism of action has been related to the increase in extracellular adenosine, which leads to the effects of A2A receptor in M1 macrophages that dampens TNFα and IL12 production and increases IL1Ra and TNFRp75. By acting on A2B receptor on M2 macrophages it enhances IL10 synthesis and inhibits NF‐kB signaling. MTX has also been shown to exert JAK inhibition of JAK2 and JAK1 when tested in Drosophila melanogaster as a model of kinase activity and in human cell lines (nodular sclerosis Hodgkin's lymphoma and acute myeloid leukemia cell lines). These effects may explain why MTX leads to clinical effects similar to anti‐TNFα biologics in monotherapy, but is less effective when compared to anti‐IL6R in monotherapy, which acting upstream exerts major effects downstream on the JAK1‐STAT3 pathway. The MTX effects on JAK1/JAK2 inhibition also allows to understand why the combination of MTX with Leflunomide, or JAK1/JAK3 inhibitor leads to better clinical outcomes than monotherapy, while the combination with JAK1/JAK2 or JAK1 specific inhibitors does not seem to exert additive clinical benefit

Allele *2 of the HS1,2A enhancer of the Ig regulatory region associates with rheumatoid arthritis

Objective: To investigate the role of the HS1.2 enhancer polymorphisms as a new candidate marker for rheumatoid arthritis (RA) and to define the possible association with autoantibody positivity and clinical outcome. Methods: Genomic DNA was obtained from two cohorts of patients with RA (100 with early RA (ERA) and 114 with longstanding RA (LSRA)) and from 248 gender-matched controls from the same geographical area. Clinical and immunological characteristics were recorded for all the patients. Results: The percentage of the 2/2 genotype was higher In patients with ERA (27.0%), and In patients with LSRA (34.2%), than In controls (14.9%) (ERA: OR = 2.11 (95% Cl 1.20 to 3.70) vs controls; LSRA: OR = 2.96 (95% Cl 1.76 to 5.00) vs controls). A lower representation of allele *3 was present In patients with ERA (2.0%) than In controls (6.0%; OR = 0.32 (95% Cl 0.11 to 0.91)). No significant associations were found between polymorphisms and autoantibodies positivity. Conclusion: The HS1.2A allele *2 associates with early and longstanding RA

Characterization of inflammatory cell infiltrate of scleroderma skin: B cells and skin score progression.

Background: The purpose of this study was to investigate the frequency and the distribution of inflammatory cell infiltrate in two sets of cutaneous biopsies derived from clinically involved and uninvolved skin of patients with systemic sclerosis (SSc) and to find correlations between the cell infiltrate and the progression of skin involvement. Methods: Immunohistochemistry was carried out to identify CD68, CD3, CD20 and CD138-positive (+) cells in clinically involved and uninvolved skin of 28 SSc patients. Patients were followed for 6 months and the characteristics of the infiltrate were analyzed according to disease duration, clinical features and skin involvement progression. Results: In all SSc cutaneous specimens, cellular infiltrates were found in a perivascular location predominantly in the mid and deeper portions of the dermis. All the analysed biopsies showed a CD3+ and CD68+ cell infiltrate and the mean number of CD3+, as well as CD68+ cells, was higher in clinically involved skin (CD3+: 71.7\ub134.6 and CD68+: 26.3\ub18.4) than in clinically uninvolved skin (CD3+: 45.7\ub136.0; CD68+: 13.6\ub16.1), (p&lt;0.001 for both comparisons). CD20+ cells were found in 17 (60.7%) patients and in these patients the mean number of CD20+ cells was higher in involved (4.7\ub15.9) than in uninvolved skin (1.9\ub12.9), (p=0.04). Early SSc had a greater number of CD20+ cells compared with patients with long-standing disease. CD138+ cells were found in 100% of involved skin biopsies and in 89.3% of uninvolved skin samples. The mean number of CD138+ cells was higher in clinically involved skin (3.6\ub12.3) than in clinically uninvolved skin (1.9\ub11.7), (p&lt;0.001). Considering the 7 patients that experienced a worsening of skin score higher than 20% after 6-month of follow-up, all of them had presented a CD20+ skin infiltrate in the involved skin biopsy. Conclusions: Our results confirm that mononuclear cells are present in the skin of all SSc patients underlining the role of inflammatory cell infiltrates in skin involvement in SSc. B cells in the skin seem to characterize patients with early diffuse skin disease and to correlate with skin progression

Differential synovial tissue biomarkers among psoriatic arthritis and rheumatoid factor/anti-citrulline antibody-negative rheumatoid arthritis

Background: Differential diagnosis among psoriatic arthritis (PsA) and seronegative rheumatoid arthritis (Ab neg RA) can be challenging particularly in the clinical setting of peripheral phenotype and autoantibodies seronegativity. The aim of the study was to identify synovial tissue (ST) biomarkers differentially expressed in PsA and Ab neg RA and test their predictive value of therapeutic response. Methods: Thirty-four PsA patients [12 DMARD naive and 22 non-responder to methotrexate (MTX-IR)] with peripheral joint involvement and 55 Ab neg RA (27 DMARD naive and 28 MTX-IR) underwent US-guided ST biopsy and immunohistochemistry (IHC) for CD68 + , CD3 + , CD20 + , CD21 + , CD117 + , and CD138 + cells. After study entry, each DMARD-naive patient started MTX therapy and was followed in an outpatient setting for at least 6 months to define the achievement of Minimal Disease Activity (PsA) and DAS remission (Ab neg RA) status respectively. Each IR-MTX patient was treated according to EULAR recommendations. Results: At study entry, IHC analysis revealed that PsA patients had comparable levels of lining and sublining CD68 + and sublining CD21 + , CD20 + , and CD3 + cells than Ab neg RA, despite the therapeutic regimen. Moreover, regardless of the therapeutic scheme, PsA patients showed higher IHC score of CD117 + cells (p = 0.0004 and p = 0.0005 for naive and MTX-IR patients respectively) compared to Ab neg RA patients. Conversely, Ab neg RA patients showed higher IHC score of CD138 + cells, irrespective to the therapeutic scheme (p = 0.04 and p = 0.002 for naive and MTX-IR patients respectively). Analyzing the response rate to the therapeutic scheme, naive PsA patients reaching MDA status at 6 months follow-up, showed, at the study entry, lower IHC score of CD3 + cells compared to PsA patients not reaching this outcome (p = 0.02); conversely, naive Ab neg RA patients reaching DAS remission status at 6 months follow-up, showed, at the study entry, lower IHC score of sublining CD68 + cells compared to Ab neg RA patients not reaching this outcome (p &lt; 0.001). Conclusions: CD117 + and CD138 + cells are differentially distributed among PsA and Ab neg RA. Histological analysis of ST may help to solve the clinical overlap between the two diseases and provides prognostic data about the therapy success