Synovial B cells of rheumatoid arthritis express ZAP-70 which increases the survival and correlates with the inflammatory and autoimmune phenotype

The unanticipated contribution of Zap70 in retinal degeneration: Implications for microglial inflammatory activation

Inflammation is a major mechanism of photoreceptor cell death in the retina during macular degeneration leading to the blindness. In this study, we investigated the role of the kinase molecule Zap70, which is an inflammatory regulator of the systemic immune system, to elucidate the control mechanism of inflammation in the retina. We observed activated microglial cells migrated and populated the retinal layer following blue LED-induced photoreceptor degeneration and activated microglial cells in the LED-injured retina expressed Zap70, unlike the inactive microglial cells in the normal retina. Visual function was considerably decreased in blue-LED light-exposed mice, and animals with Zap70 mutations were adversely affected. Furthermore, extensive photoreceptor cell death was observed in the SKG mice, bearing a Zap70 mutation that induces autoimmune disease. In the blue-LED light-exposed groups, SKG retinas had significantly higher levels of inflammatory cytokines than those in wild-type mice. Furthermore, regulating Zap70 activity has a significant influence on microglial inflammatory state. We discovered that active microglial cells expressing Zap70 could modify vascular endothelial growth factor A (Vegfa) signaling in primary retinal pigment epithelial (RPE) cells. Our novel study revealed that the production of Zap70 by retinal microglial cells is responsible for inflammatory signals that promote apoptosis in photoreceptor cells. Furthermore, Zap70-positive microglial cells were capable of regulating Vegfa signaling in RPE cells, which matches the hallmark of macular degeneration. Overall, we discovered Zap70's inflammatory activity in the retina, which is necessary for upregulating multiple inflammatory cytokines and cell death. Zap70 represents a novel therapeutic target for treating retinal degeneration.

Normal B cells express ZAP70 in chronic lymphocytic leukemia: A link between autoimmunity and lymphoproliferation?

ZAP70 has a prognostic value in chronic lymphocytic leukemia (CLL), through altered B-cell receptor signaling, which is important in CLL pathogenesis. A good correlation between ZAP70 expression in CLL cells and the occurrence of autoimmune phenomena has been reported. Yet, the great majority of CLL-associated autoimmune cytopenia is due to polyclonal immunoglobulin (Ig) G synthesized by nonmalignant B cells, and this phenomenon is poorly understood. Here, we show, using flow cytometry, that a substantial percentage of CD5- nonmalignant B cells from CLL patients expresses ZAP70 compared with CD5- B cells from healthy subjects. This ZAP70 expression in normal B cells from CLL patients was also evidenced by the detection of ZAP70 mRNA at single-cell level with polyclonal Ig heavy- and light-chain gene transcripts. ZAP70+ normal B cells belong to various B-cell subsets and their presence in the naïve B-cell subset suggests that ZAP70 expression may occur during early B-cell development in CLL patients and potentially before malignant transformation. The presence of ZAP70+ normal B cells is associated with autoimmune cytopenia in CLL patients in our cohort of patients, and recombinant antibodies produced from these ZAP70+ nonmalignant B cells were frequently autoreactive including anti-platelet reactivity. These results provide a better understanding of the implication of ZAP70 in CLL leukemogenesis and the mechanisms of autoimmune complications of CLL.

Significance of PPARA as a Treatment Target for Chronic Lymphocytic Leukemia

Peroxisome proliferator-activated receptor alpha (PPARA) has been suggested as a therapeutic target for chronic lymphocytic leukemia (CLL). However, the underlying molecular mechanism remains largely unclear. In this study, we analyzed DNA next-generation sequencing (NGS) data and clinical information from 86 CLL patients to identify gene markers related to treatment-free survival (TFS) length. We then constructed a genetic network that includes CLL promoters, treatment targets, and TFS-related marker genes. To assess the significance of PPARA within the network, we utilized degree centrality (DC) and pathway enrichment score (EScore). Clinical and NGS data revealed 10 TFS length-related gene markers, including RPS15, FOXO1, FBXW7, KMT2A, NOTCH1, GNA12, EGR2, GNA13, KDM6A, and ATM. Through literature data mining, 83 genes were identified as CLL upstream promoters and treatment targets. Among them, PPARA exhibited a stronger connection to CLL and TFS-related gene markers, as evidenced by its ranking at No. 13 based on DC, compared to most of the other promoters (>84%). Additionally, PPARA co-functions with 70 out of 92 in-network genes in various functional pathways/gene groups related to CLL pathology, such as regulation of cell adhesion, inflammation, reactive oxygen species, and cell differentiation. Based on our findings, PPARA is considered one of the critical genes within a large genetic network that influences the prognosis and TFS of CLL through multiple pathogenic pathways.

Identification of key genes and immune profile in limited cutaneous systemic sclerosis-associated pulmonary arterial hypertension by bioinformatics analysis

AIMS

Limited cutaneous systemic sclerosis-associated pulmonary arterial hypertension (lcSSc-PAH) is a complex multi-system disease with high morbidity and mortality. The purpose of this study is to identify the hub genes and immune characteristics of limited cutaneous systemic sclerosis (lcSSc) and lcSSc-PAH through bioinformatics.

MAIN METHODS

LcSSc-PAH raw data were obtained from the GEO database (GSE19617). Weighted gene Co-expression Network analysis (WGCNA) was used to evaluate key modules. Then, we performed Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis with R software and verified the diagnostic value of the hub genes. Finally, Immune Cell Abundance Identifier (ImmuCellAI) was used to analyze the immune characteristics of the normal subjects, lcSSc and lcSSc-PAH patients, the results were displayed graphically.

KEY FINDINGS

Enrichment of two important modules by GO and KEGG identified key biological processes and pathways related to pathogen infection and immune function. Three hub genes (BID, IFNGR1, ZAP70) related to immune function were identified. The analysis of immune characteristics showed that the correlation and abundance of immune cells such as inducible regulatory T (iTreg) cells, B cells, macrophages, natural killer (NK) cells, CD8T cells, mucosal-associated invariant T(MAIT) cells and dendritic cells(DCs) were significantly different in the normal subjects, lcSSc and lcSSc-PAH patients.

SIGNIFICANCE

Pathogen infection, changes in the number and function of immune cells, and interactions among immune cells may preliminarily reveal the pathological mechanism of lcSSc-PAH. The hub genes, pathways and immune characteristics identified in this research remains to be further studied.

Novel compound heterozygous mutations in ZAP70 in a Chinese patient with leaky severe combined immunodeficiency disorder

In humans, the complete lack of tyrosine kinase ZAP70 function results in combined immunodeficiency (CID), with abnormal thymic development and defective T cell receptor (TCR) signaling of peripheral T cells, characterized by the selective absence of CD8⁺ T cells. So far, 15 unique ZAP70 mutations have been identified in approximately 20 patients with CID, with variable clinical presentations. Herein, we report the first case from China of novel compound heterozygous mutations in ZAP70 (c.598-599delCT, p.L200fsX28; c.847 C>T, R283H). The patient suffered from early-onset and recurrent infections, but showed normal growth and development without signs of failure to thrive, thus presenting as leaky SCID. The patient also had clinical manifestations of autoimmunity, such as eczematous skin lesion, inflammatory bowel disease (IBD), and intractable diarrhea, suggesting compromised T cell tolerogenic functions. Residual ZAP70 expression was identified. Immunological analysis revealed the selective absence of CD8⁺ T cells in the periphery and the presence of CD4⁺ T cells that failed to respond to phytohemagglutinin. Stimulation with lectin from pokeweed mitogen also failed to stimulate B cell proliferation in the patient. The frequency of Tfhs and Tregs in the patient was lower compared with the normal reference. Compared with the age-matched healthy control, the level of IL-17 was higher and the levels of IFN-γ, IL-4, and IL-21 were lower. Infants with selected CD8 deficiency and severe autoimmune disorders or exaggerated inflammation should be screened for ZAP70 deficiency.

Collagen Specific T-Cell Repertoire and HLA-DR Alleles: Biomarkers of Active Refractory Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by chronic joint inflammation and associates with HLA-DRB1*04. The Collagen IIp_261-273-specific T cell repertoire in the peripheral blood of DR4 + patients at the onset of the disease shows a restricted TCR-beta chain usage among which the most frequent is TRBV25.

To define whether this group of DR4-restricted collagen-specific shared T cell could represent markers of active-severe disease and response to therapy, 90 subjects affected by early-RA were enrolled in the study; peripheral blood mononuclear cells were cultured with or without the human collagen II peptide p261-273 and were examined by immunoscope analysis for the usage of the previously identified shared TCR-beta chains.

We report that the presence of T cells carrying rearrangement TRBV25 associated with HLA-DR haplotype and disease activity. HLA-DRB1* haplotypes 04–04, 04–01 and 04–11 were significantly associated with usage of TRBV25, higher disease activity at the onset of disease and poor response to DMARDs.

Finally, the HLA-DRB1* haplotype appeared complementary with current serologic tools to predict good and poor responders in a treat to target strategy. The data reported here offer clues to predict the course of the disease and to foresee personalized treatments in RA patients.

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In DR4 + RA patients disease activity is associated with detection of Collagen_261-273-specific T cells carrying TRBV25.

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HLA-DR 04/04, 04/01 and 04/11 alleles were associated with TRBV25, DAS at the onset, and poor response to DMARDs.

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These findings could lead to tailor the treatment in the subgroup of patients with an active refractory disease.

In the era of costly medical care with monoclonal antibodies and new molecules, and of an increasing request of a personalized medicine, a relevant socio-economic problem in the management of Rheumatoid Arthritis patients is the possible identification of the subgroups of poor responders to treatment. Our study aimed to detect the refractory active patients using an HLA-DR test (available in most hospital centers) combined with a relatively new biomarker of active disease expressed on the cell surface of autoreactive T cells. These tests appear complementary tools to identify the best and the poor responders to a “treat to target strategy”.

Identifying genes related with rheumatoid arthritis via system biology analysis

Rheumatoid arthritis (RA) is a chronic, inflammatory joint disease that mainly attacks synovial joints. However, the underlying systematic relationship among different genes and biological processes involved in the pathogenesis are still unclear. By analyzing and comparing the transcriptional profiles from RA, OA (osteoarthritis) patients as well as ND (normal donors) with bioinformatics methods, we tend to uncover the potential molecular networks and critical genes which play important roles in RA and OA development. Initially, hierarchical clustering was performed to classify the overall transcriptional profiles. Differentially expressed genes (DEGs) between ND and RA and OA patients were identified. Furthermore, PPI networks were constructed, functional modules were extracted, and functional annotation was also applied. Our functional analysis identifies 22 biological processes and 2 KEGG pathways enriched in the commonly-regulated gene set. However, we found that number of set of genes differentially expressed genes only between RA and ND reaches up to 244, indicating this gene set may specifically accounts for processing to disease of RA. Additionally, 142 biological processes and 19 KEGG pathways are over-represented by these 244 genes. Meanwhile, although another 21 genes were differentially expressed only in OA and ND, no biological process nor pathway is over-represented by them.

Memory B cell subsets and plasmablasts are lower in early than in long-standing rheumatoid arthritis

BACKGROUND

Alterations of B cell subset distribution have been described in the peripheral blood (PB) of rheumatoid arthritis (RA) patients, but no data are available on differences between the onset and the established phases of the disease. The purpose of the study was to clarify whether a peculiar distribution of B cell subsets characterizes RA onset, thus leading to a more favorable clinical response to treatment, and to evaluate the possible association of a particular B cell subpopulation with response to therapy.

RESULTS

122 RA patients were enrolled: 25 had symptom duration less than 3 months and were defined as having "very early RA" (VERA), and 43 had symptom duration from more than 3 months up to one year (early-RA: ERA). The other 54 RA patients had long-standing RA (LSRA). At baseline and at 6-month follow-up visit peripheral blood samples were collected and analyzed by flow cytometry for the distribution of circulating B cell subsets by staining with surface markers CD45, CD19, CD38, CD27 and IgD and intracellular marker ZAP70.VERA and ERA patients showed higher percentages and absolute counts of circulating antigen inexperienced naïve B cells (IgD + CD27-) and lower percentages and absolute numbers of double negative (IgD-CD27-) memory B cells and plasmablasts (CD38 + CD27+) compared to LSRA patients. At the multivariate analysis, a higher frequency of naïve B cells (IgD + CD27-) at baseline arose as significant predictor of CDAI remission, together with "having VERA disease" and a low disease activity at baseline.

CONCLUSIONS

The onset of RA is characterized by higher percentages and absolute numbers of naïve B cells and lower numbers of plasmablasts and double negative memory B cells compared to established RA. Naïve B cells could represent a promising biomarker of outcome.

Relationship between redox status and cell fate in immunity and autoimmunity

SIGNIFICANCE

The signaling function of redox molecules is essential for an efficient and proper execution of a large number of cellular processes, contributing to the maintenance of cell homeostasis. Excessive oxidative stress is considered as playing an important role in the pathogenesis of autoimmune diseases by enhancing inflammation and breaking down the immunological tolerance through protein structural modifications that induce the appearance of neo/cryptic epitopes.

RECENT ADVANCES

There is a complex reciprocal relationship between oxidative stress and both apoptosis and autophagy, which is essential to determine cell fate. This is especially relevant in the context of autoimmune disorders in which apoptosis and autophagy play a crucial pathogenic role.

CRITICAL ISSUES

In this review, we describe the latest developments with regard to the involvement of redox molecules in the initiation and progression of autoimmune disorders, focusing on their role in cell fate regulation. We also discuss new therapeutic approaches that target oxidative stress in the treatment of these disorders. The administration of antioxidants is scarcely studied in autoimmunity, and future analyses are needed to assess its beneficial effects in preventing or ameliorating these diseases.

FUTURE DIRECTIONS

Deciphering the intricate relationships between oxidative stress and both apoptosis and autophagy in the context of autoimmunity could be critical in elucidating key pathogenic mechanisms and could lead to novel interventions for the clinical management of autoimmune diseases.

ZAP-70+ B cell subset influences response to B cell depletion therapy and early repopulation in rheumatoid arthritis

OBJECTIVE

To define the role of ZAP-70+ B cells (CD19+/ZAP-70+) as a biomarker of response to B cell depletion therapy (BCDT), their relationship with clinical outcome, and their behavior during repopulation of peripheral blood in patients with rheumatoid arthritis (RA).

METHODS

Thirty-one patients with RA underwent BCDT and were followed for 12 months. Disease activity was assessed with the European League Against Rheumatism (EULAR) criteria. Cytofluorimetric analysis of peripheral blood B cell subsets at baseline and at 6- and 12-month intervals after BCDT was performed using surface markers (CD45, CD3, CD56, CD19, IgD, CD38, CD27) and intracellular ZAP-70.

RESULTS

A moderate/good EULAR response was achieved in 66.6% of the RA cohort. The baseline percentage of CD19+/ZAP-70+ cells was lower in good responder patients (1.8% ± 1.7%) compared to poor responders (5.6% ± 4.9%; p = 0.02). A decrease of plasmablasts (IgD-CD27+CD38+) and pre-switch memory (IgD+CD27+) B cells occurred after BCDT. Recovery of B cells in peripheral blood after the first course of BCDT was characterized by the reappearance of B cell subtypes that showed a naive, activated phenotype, coupled with a decrease in memory cells. B cells carrying intracytoplasmic ZAP-70 increased significantly from the baseline value of 4.4% ± 4.5% to 12.4% ± 9.2% (p = 0.001) at the 6-month and to 9.4% ± 6.4% (p = 0.002) at the 12-month followup.

CONCLUSION

Baseline percentage of CD19+/ZAP-70+ cells is associated with the clinical outcome after BCDT in patients with RA. Depletion of plasmablasts and pre-switch memory B cells and increase of CD19+/ZAP-70+ cells are features of the recovery of the B cell pool after BCDT.

Initiation but no execution - modulation of peripheral blood lymphocyte apoptosis in rheumatoid arthritis - a potential role for heat shock protein 70

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disease, which causes synovial damage. Persistence of lymphocyte infiltrates in the rheumatoid synovium has been attributed to abnormal apoptosis. While not comprehensively investigated, perturbations in peripheral blood lymphocyte (PBL) apoptosis may also be involved in perpetuation of autoimmune processes in RA.

Methods

We investigated total, CD4+ and CD19+ PBL apoptosis in our study cohort by monitoring the translocation of phosphatidylserine using the Annexin-V assay. To examine the role of death receptor mediated apoptosis as well as activation-induced-cell-death (AICD), PBLs were labeled with CD95/Fas and CD69 markers and enumerated by flow cytometry. Proteolytic activity of initiator and executioner caspases was determined by luminometry. DNA fragmentation assays were used to examine whether apoptotic signals were transduced to the nucleus. Quantitative PCR arrays were used to investigate apoptotic pathways associated with RA-PBLs. Since heat-shock-protein-70 (HSP70) is an inducible protein which modulates apoptotic signals, we determined HSP70 levels by intra-cellular flow cytometry and western blots.

Results

The RA-PBLs showed signs of elevated apoptosis whilst in circulation. These include increases in the loss of plasma membrane asymmetry, indicated by increased externalization of phosphatidylserine (especially in B-lymphocytes). RA-PBLs showed a bias to CD95/Fas mediated apoptotic pathways, but low levels of the CD69 marker suggested that this was not associated with immune activation. Although downstream markers of apoptosis such as caspase-3/7 activity, were increased, no DNA fragmentation was observed in RA-PBLs. Interestingly, elevated levels of apoptosis did not correlate with absolute lymphocyte counts in RA patients. Levels of HSP70 were highly elevated in RA-PBLs compared to controls.

Conclusion

The results suggest that while apoptosis may be initiated in RA-PBLs, they may lack commitment to fully executing the apoptotic program. This may be related to inhibition on apoptotic transduction by HSP70. This study provides evidence that abnormalities in RA-PBLs apoptosis may occur whilst still in circulation and may contribute to pathogenesis of the disease.

Pathogenetic, clinical and pharmaco-economic assessment in rheumatoid arthritis (RA)

Rheumatoid arthritis (RA) has become one of the most studied autoimmune chronic inflammatory diseases (ACIDs), either from the pathogenetic or from the therapeutic point of view. It is recognized that synovial fibroblasts, TH1 and TH17 cells likely play along with the B cells the most relevant role. The disease has a polygenic background that characterizes the seropositive and the seronegative subsets. Over the years, we realized that no more than 15-20% of long-standing RA (LSRA) treated with conventional drugs can reach full remission, whereas the most recent data in early RA (ERA) have demonstrated that 40-60% can be put into clinical and biological remission. This of course is of crucial importance to avoid any progression of the structural damage that leads to functional disability. If we consider that a disability index score (Health Assessment Questionnaire 0-3) of a severe arthritis can cost up to 21,000 EUs, while a mild disease will cost not more than 5,500 EUs per year, it appears very clear that a low disease activity (LDA) or a remission state (Rem) should be the aim in each single patient, in order to keep the workability and maintain the productivity. This is and should be the major aim in each RA patient.

B-cell subsets in the joint compartments of seropositive and seronegative rheumatoid arthritis (RA) and No-RA arthritides express memory markers and ZAP70 and characterize the aggregate pattern irrespectively of the autoantibody status

The aim of the present study was to determine whether different subsets of B cells characterize synovial fluid (SF) or synovial tissue (ST) of seropositive or seronegative rheumatoid arthritis (RA) with respect to the peripheral blood (PB). PB, SF and ST of 14 autoantibody (AB)-positive (rheumatoid factor [RF]-IgM, RF-IgA, anti-citrullinated peptide [CCP]), 13 negative RA and 13 no-RA chronic arthritides were examined for B-cell subsets (Bm1-Bm5 and IgD-CD27 classifications), zeta-associated protein kinase-70 (ZAP70) expression on B cells and cytokine levels (interleukin [IL]-1β, tumor necrosis factor [TNF]-α, IL-6, IL-8 and monocyte chemotactic protein [MCP]-1). Synovial tissues were classified as aggregate and diffuse patterns. No differences were found in B-cell percentages or in subsets in PB and SF between AB(+) and AB(-) RA and no-RA. In both AB(+) and AB(-) RA (and no-RA), the percentage of CD19(+)/ZAP70(+) was higher in SF than in PB (AB(+): P = 0.03; AB(-): P = 0.01; no-RA: P = 0.01). Moreover, SF of both AB(+) and AB(-) RA (and no-RA) patients was characterized by a higher percentage of IgD-CD27(+) and IgD-CD27(-) B cells and lower percentage of IgD(+)CD27(-) (P < 0.05) B cells compared to PB. In SF, ZAP70 positivity is more represented in B cell CD27(+)/IgD(-)/CD38(-). The aggregate synovitis pattern was characterized by higher percentages of Bm5 cells in SF compared with the diffuse pattern (P = 0.05). These data suggest that no difference exists between AB(+) and AB(-) in B-cell subset compartmentalization. CD27(+)/IgD(-)/ZAP70(+) memory B cells accumulate preferentially in the joints of RA, suggesting a dynamic maturation of the B cells in this compartment.