Autoantibodies against the melanoma differentiation-associated protein 5 in patients with dermatomyositis target the helicase domains

OBJECTIVES

Clinical observations in patients with dermatomyositis (DM) and autoantibodies against the melanoma differentiation-associated protein 5 (MDA5) suggest that the autoantibodies contribute to the pathogenesis of MDA5(+) DM. To gain insight into the role of the anti-MDA5 autoantibodies, we aimed to identify their binding sites on the different domains of the MDA5 protein.

METHODS

We developed an in-house ELISA to assess the reactivity against the MDA5 domains (conformational epitopes) in plasma (n = 8) and serum (n = 24) samples from MDA5(+) patients with varying clinical manifestations and disease outcomes. The reactivities were also assessed using western blot (linearized epitopes). An ELISA-based depletion assay was developed to assess cross-reactivity among the different MDA5 domains.

RESULTS

All eight plasma samples consistently showed reactivity towards conformational and linearized epitopes on the helicase domains of the MDA5 protein. The ELISA-based depletion assay suggests that anti-MDA5 autoantibodies specifically target each of the three helicase domains. Twenty-two of the 24 serum samples showed reactivity in the in-house ELISA and all 22 displayed reactivity towards the helicase domains of the MDA5 protein.

CONCLUSIONS

Our data revealed that the main immunogenic targets of anti-MDA5 autoantibodies from MDA5(+) patients are the helicase domains. Considering that the helicase domains are responsible for the enzymatic activity and subsequent triggering of an inflammatory response, our findings suggest that binding of anti-MDA5 autoantibodies could alter the canonical activity of the MDA5 protein and potentially affect the downstream induction of a pro-inflammatory cascade.

Single-cell profiling of muscle-infiltrating T cells in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) are rare autoimmune systemic diseases characterized by muscle weakness and the presence of muscle-infiltrating T cells. IIM represent a clinical challenge due to heterogeneity of symptoms and variability of response to immunosuppressive treatment. Here, we performed in-depth single-cell sequencing on muscle-infiltrating T cells and peripheral blood memory T cells in six patients with recently diagnosed IIM. We identified tissue resident memory T-cell (TRM ) signatures including the expression of HOBIT, XCL1 and CXCR6 in the muscle biopsies of all patients with IIM. Clonally expanded T-cell clones were mainly found among cytotoxic and TRM implying their role in the disease pathogenesis. Finally, identical expanded T-cell clones persisting at follow-up in the muscle tissue of two patients suggest their involvement in disease chronicity. Our study reveals a muscle tissue resident memory T-cell signature in patients with IIM and a transcriptomic map to identify novel therapeutic targets in IIM.

Occurrence and localization of FOXP3 + cells in kidney biopsies in lupus nephritis and ANCA-associated vasculitis

The study aims to increase the understanding regarding the role of regulatory T cells (Tregs) in lupus nephritis (LN) and ANCA-associated vasculitis (AAV) by comparing their localization in renal tissue and changes following immunosuppressive therapy. Kidney biopsies from 12 patients with LN and 7 patients with AAV were examined. Kidney biopsies had been performed both at active disease and following immunosuppressive treatment. Clinical data was collected at both biopsy occasions. Expression of Forkhead Box P 3 (Foxp3) in renal tissue was assessed by immunohistochemistry. An arbitrary scale was used to estimate the number of Foxp3+ cells. In LN, 8/12 (67%) had positive tissue staining for Foxp3 at baseline, most pronounced in inflammatory infiltrates, but also interstitially and in a peri-glomerular pattern. At second biopsies, after immunosuppressive treatment, 4/12 (33%) still had detectable Foxp3+ cells, found in persisting inflammatory infiltrates and some in the interstitium. Patients with a good clinical response to treatment had high grade of Foxp3+ cells in first biopsies. In AAV, only 2/7 (29%) had positive staining for Foxp3 at baseline, in inflammatory infiltrates and to a lesser extent in the interstitium, despite large areas of inflammatory infiltrates in all patients. At follow-up, 2/7 (29%) biopsies were positive for Foxp3. Our data show a higher presence of Foxp3+ cells in renal tissue from LN patients compared to AAV, suggesting that Tregs may be differently involved in the control of inflammatory mechanisms in these diseases. These findings could have further implication for therapeutic approaches aiming at restoring the immunological tolerance. Key Points • Foxp3+-cells are present in larger amount in renal tissue in lupus nephritis vs. ANCA-associated vasculitis. • Our data suggest that Foxp3+ regulatory T cells are involved in the control of inflammatory processes in lupus nephritis.

Diversity and Clonality of T Cell Receptor Repertoire and Antigen Specificities in Small Joints of Early Rheumatoid Arthritis

OBJECTIVE

CD4+ T cells are implicated in rheumatoid arthritis (RA) pathology from the strong association between RA and certain HLA class II gene variants. This study was undertaken to examine the synovial T cell receptor (TCR) repertoire, T cell phenotypes, and T cell specificities in small joints of RA patients at time of diagnosis before therapeutic intervention.

METHODS

Sixteen patients, of whom 11 patients were anti-citrullinated protein antibody (ACPA)-positive and 5 patients were ACPA-, underwent ultrasound-guided synovial biopsy of a small joint (n = 13) or arthroscopic synovial biopsy of a large joint (n = 3), followed by direct sorting of single T cells for paired sequencing of the αβ TCR together with flow cytometry analysis. TCRs from expanded CD4+ T cell clones of 4 patients carrying an HLA-DRB1*04:01 allele were artificially reexpressed to study antigen specificity.

RESULTS

T cell analysis demonstrated CD4+ dominance and the presence of peripheral helper T-like cells in both patient groups. We identified >4,000 unique TCR sequences, as well as 225 clonal expansions. Additionally, T cells with double α-chains were a recurring feature. We identified a biased gene usage of the V_β chain segment TRBV20-1 in CD4+ cells from ACPA+ patients. In vitro stimulation of T cell lines expressing selected TCRs with an extensive panel of citrullinated and viral peptides identified several different virus-specific TCRs (e.g., human cytomegalovirus and human herpesvirus 2). Still, the majority of clones remained orphans with unknown specificity.

CONCLUSION

Minimally invasive biopsies of the RA synovium allow for single-cell TCR sequencing and phenotyping. Clonally expanded, viral-reactive T cells account for part of the diverse CD4+ T cell repertoire. TRBV20-1 bias in ACPA+ patients suggests recognition of common antigens.

Modulating T-cell activation with antisense oligonucleotides targeting lymphocyte cytosolic protein 2

Dysregulated T-cell activation is a hallmark of several autoimmune diseases such as rheumatoid arthritis (RA) and multiple sclerosis (MS). The lymphocyte cytosolic protein 2 (LCP2), also known as SLP-76, is essential for the development and activation of T cells. Despite the critical role of LCP2 in T-cell activation and the need for developing drugs that modify T-cell activation, no LCP2 inhibitors have been developed. This can be explained by the "undruggable" nature of LCP2, lacking a structure permissive to standard small molecule inhibitor modalities. Here, we explored an alternative drug modality, developing antisense oligonucleotides (ASOs) targeting LCP2 mRNAs, and evaluated its activity in modulating T-cell activation. We identified a set of 3' UTR targeting LCP2 ASOs, which knocked down LCP2 in a human T-cell line and primary human T cells and found that these suppressed T-cell receptor mediated activation. We also found that the ASOs suppressed FcεR1-mediated mast cell activation, in line with the role of LCP2 in mast cells. Taken together, our data provide examples of how immunomodulatory ASOs that interfere with undruggable targets can be developed and propose that such drug modalities can be used to treat autoimmune diseases.

POS0905 CHARACTERISATION OF SWEDISH MYOSITIS PATIENTS WITH ANTI-MDA5 AUTOANTIBODIES AND CORRELATION OF CLINICAL FEATURES WITH AUTOANTIBODY LEVELS

Background

The association between anti-melanoma differentiation association protein 5 autoantibodies (aMDA5) and rapidly progressive interstitial lung disease (RP-ILD) in clinically amyopathic dermatomyositis is well established in Asian population cohorts. In western cohorts, ILD has been strongly associated with aMDA5 but data regarding RP-ILD have been more conflicting. It is also suggested that western cohorts have more pronounced myopathic features than Asian.

Objectives

To characterise the disease manifestations of a Swedish aMDA5 positive idiopathic inflammatory myositis (IIM) cohort and to explore antigen reactivity of the MDA5 protein.

Methods

First available serum samples collected from 28 consecutive patients with IIM and positive aMDA5 ever tested by ELISA, Line Blot (LB) or Immunoprecipitation, attending Karolinska University Hospital between 1999 and 2021, were included. Clinical data including presence of anti-SSA autoantibodies by ELISA or LB was retrieved retrospectively. An in-house ELISA was used to screen serum samples for reactivity against a recombinant MDA5 protein (rMDA5, aa A110-D1025, UniProt ID Q9BYX4) and seven MDA5-derived constructs containing different domains. Correlations between aMDA5 reactivity levels and clinical data were explored.

Results

Nine patients showed no reactivity to any of the rMDA5 constructs by ELISA and were excluded from further analysis.

Reactivity against rMDA5 was confirmed by ELISA in 19 patients (median 184.7 µg/mL (interquartile range (IQR) 277.07). The cohort included 13 male and 6 female patients, 94% Caucasian, with mean age at diagnosis of 41.05 years (standard deviation (SD) 10.5). Median disease duration at time of sampling was 0 months (IQR 1). All patients except one had signs of muscle involvement (muscle weakness, elevated muscle enzymes, muscle oedema or muscle biopsy consistent with myositis). At diagnosis 63.2% of patients reported muscle weakness (21.1 % had a manual muscle test 8 score <75). Dermatological findings were observed in 17/19 (89.7 %). During disease course nine patients (47.4%) had confirmed arthritis.

ILD was diagnosed in 16/19 patients (84.2%), four of these (25%) developed a RP-ILD. One patient passed away due to RP-ILD and one required a lung transplant. Patients with ILD had a statistically significant higher mean age at diagnosis than those without (42.8.5 (SD 10.3) vs 31.3 (SD 4.7) years, p=0.02). Patients developing RP-ILD were not significantly older than patients with chronic ILD. Respiratory symptoms were reported by 75% of patients with ILD at time of diagnosis. The mean total lung capacity (TLC) of the ILD cohort was 68% (SD 17), mean diffusion capacity of carbon monoxide (DLCO) was 59% (SD 15) and mean forced vital capacity (FVC) was 62% (SD 19). There was a higher proportion of patients with CRP ≥ 3 times the reference range at diagnosis amongst patients with FVC <70 % than patients with FVC >70 % (88.9 % vs 16.7 %, p= 0.01).

Ten patients (52.6%) had anti-SSA autoantibodies, all had ILD. Anti-SSA positive patients had a statistically significant lower TLC than those without (62% vs 79% respectively, p=0.04) and a lower FVC (57% vs 76% respectively, p=0.05).

We found a weak non-statistically significant negative correlation between titres of aMDA5 and TLC, DLCO and FVC (Pearson coefficients -0.187, -0.289, -0.130 respectively). Frequency of ILD was higher in patients with aMDA5 titres >100 µg/mL than those with titers <100, but not statistically significant (81.3% vs 18.8%, respectively).

Conclusion

In this Caucasian cohort of aMDA5 positive IIM patients, ILD was present in over 80% of patients, of these, one quarter had RP-ILD. Older patients were more likely to present with ILD. Anti-SSA positivity and higher CRP levels were associated with worse lung function. We found a weak negative correlation between aMDA5 titres and lung function tests, as well as a trend of higher frequency of ILD in patients with higher aMDA5 titres. Muscle and skin involvement were found in a high proportion of patients.

Acknowledgements

D. Demirdal & E. Van Gompel contributed equally to this abstract.

Disclosure of Interests

Deniz Demirdal: None declared, Eveline Van Gompel: None declared, Edvard Wigren: None declared, Maryam Dastmalchi: None declared, Begum Horuluoglu: None declared, Angeles Shunashy Galindo-Feria: None declared, Susanne Gräslund: None declared, Karine Chemin: None declared, Ingrid E. Lundberg Shareholder of: Roche and Novartis., Consultant of: Consulting fees from Corbus Pharmaceuticals Inc, Astra Zeneca, Bristol Myer´s Squibb, Corbus Pharmaceutical, EMD Serono Research & Development Institute, Argenx, Octapharma, Kezaar, Orphazyme, and Janssen, Grant/research support from: Research grants from Astra Zeneca, Antonella Notarnicola Speakers bureau: compensation for lecture at conference sponsored by Boehringer Ingelheim.

Rituximab in Systemic Lupus Erythematosus: Transient Effects on Autoimmunity Associated Lymphocyte Phenotypes and Implications for Immunogenicity

B cell abnormalities are common in systemic lupus erythematosus (SLE), and include expansion of double negative (DN) and age-associated-like B cells (ABC-like). We aimed to investigate rituximab (RTX) effects on DN and ABC-like B-cell subsets and, when possible, also secondary effects on T cells. Fifteen SLE patients, fulfilling the ACR 1982 criteria, starting RTX and followed longitudinally up to two years, were analyzed for B- and T- lymphocyte subsets using multicolor flow cytometry. DN were defined as IgD-CD27- and ABC-like as CD11c+CD21- within the DN gate. Additional phenotyping was performed adding CXCR5 in the B-cell panel. Cellular changes were further analyzed in the context of the generation of anti-drug antibodies (ADA) against RTX and clinical information. The SLE patients were mainly females (86.6%), of median age 36.7 (29.8-49.4) years and disease duration of 6.1 (1.6-11.8) years. Within the DN subset, ABC-like (IgD-CD27-CD11c+CD21-) B cell frequency reduced from baseline median level of 20.4% to 11.3% (p=0.03), at early follow-up. The DN B cells were further subdivided based on CXCR5 expression. Significant shifts were observed at the early follow-up in the DN2 sub-cluster (CD11c+CXCR5-), which reduced significantly (-15.4 percentage points, p=0.02) and in the recently described DN3 (CD11c-CXCR5-) which increased (+13 percentage points, p=0.03). SLE patients treated with RTX are at high risk of developing ADA. In our cohort, the presence of ADA at 6 months was associated with lower frequencies of DN cells and to a more pronounced expansion of plasmablasts at early follow-up. The frequency of follicular helper T cells (T_FH, CD4+PD-1+CXCR5+) and of peripheral helper T cells (T_PH, CD4+PD-1+CXCR5-) did not change after RTX. A sub-cluster of PD-1^highCD4+ T cells showed a significant decrease at later follow-up compared to early follow-up (p=0.0039). It is well appreciated that RTX transiently influences B cells. Here, we extend these observations to cell phenotypes which are believed to directly contribute to autoimmunity in SLE. We show early transient effects of RTX on ABC-like memory B cells, later effects on PD-1^high CD4+ cells, and possible implications for RTX immunogenicity. Further insight in such effects and their monitoring may be of clinical relevance.

Effect of Dentin Moisture in Posterior Restorations Performed with Universal Adhesive: A Randomized Clinical Trial

OBJECTIVES

This double-blind, randomized clinical trial evaluated the influence of dentin moisture on postoperative sensitivity (POS), as well as, on clinical performance in posterior bulk-fill composite restorations, using a universal adhesive, until 12 months after clinical service.

METHODS AND MATERIALS

In accordance with a split-mouth design, 45 patients received posterior restorations, restored with a bulk-fill resin composite (Filtek Bulk Fill, 3M Oral Care) and a universal adhesive used in etch-and-rinse mode (SBU; Single Bond Universal Adhesive), which were applied on dry or moist dentin, with a cavity depth of at least 3 mm. Three operators placed 90 Class I/Class II restorations. Patients were evaluated for spontaneous and stimulated POS in the baseline, and after 48 hours, 7 days, and at 6 and 12 months. In addition, secondary parameters (marginal discoloration, marginal adaptation, fracture, and recurrent caries) were evaluated by World Dental Federation (FDI) criteria after 7 days and at 6 and 12 months. Statistical analyzes were performed using the Chi-square, Fisher exact, Friedman, Kruskall-Wallis, and Mann-Whitney tests (α=0.05).

RESULTS

No significant spontaneous and stimulated POS was observed when SBU was applied in dry and moist dentin (p>0.05). A significant and higher risk of spontaneous POS (20.0%; 95%CI 10.9-33.82 for dry dentin and 22.22%; 95%CI 12.54-36.27 for moist dentin) occurred up to 48 hours after restoration placement for the dry and moist dentin groups (p<0.02). However, the POS intensity was mild up to 48 hours with no significant difference between dry and moist dentin groups (p>0.79). When secondary parameters were evaluated, no significant differences between the groups were observed.

CONCLUSION

Dentin moisture did not influence POS in posterior bulk-fill composite restorations when associated with a universal adhesive applied in etch-and-rinse mode.

Evaluation of At-home Bleaching Times on Effectiveness and Sensitivity with 10% Hydrogen Peroxide: A Randomized Controlled Double-blind Clinical Trial

OBJECTIVES

The aim of this randomized double-blind controlled clinical trial was to evaluate different protocols for at-home use of 10% hydrogen peroxide in whitening effectiveness and tooth sensitivity.

METHODS

Seventy-two patients were selected according to the inclusion and exclusion criteria, with the upper central incisors having color A2 or darker according to the Vita Classical scale (VITA Zahnfabrik, Bad Säckingen, Germany) and randomized into two groups: 10% hydrogen peroxide applied once daily for 15 minutes (HP 15) or applied once daily for 30 minutes (HP 30). Bleaching was performed for 14 days in both groups. The color was evaluated before bleaching, during bleaching (1st and 2nd weeks), and 1 month after the bleaching treatment using the Vita Classical, Vita Bleachedguide 3D-MASTER, and Vita Easyshade spectrophotometer (VITA Zahnfabrik). Dental sensitivity was recorded by the patients using the numerical rating scale (0-4) and visual analogue scale (0-10 cm). Color data were evaluated by two-way analysis of variance (ANOVA) of repeated measures (group vs. treatment time). The Mann-Whitney test was performed to contrast the means (α=0.05). Tooth sensitivity was assessed by Fisher's exact test (p=1.00) and intensity of tooth sensitivity was evaluated by the Mann-Whitney test (α=0.05) for both scales.

RESULTS

A significant whitening effect was observed after 2 weeks of bleaching for all color measurements (p=0.01), with no difference between HP 15 and HP 30 (p>0.05). Also, the absolute risk and intensity of tooth sensitivity were similar (47%; p>0.05).

CONCLUSIONS

The effectiveness and tooth sensitivity of at-home bleaching carried out with 10% hydrogen peroxide applied for 15 minutes or 30 minutes are similar.

POS0003 RITUXIMAB THERAPY IN SYSTEMIC LUPUS ERYTHEMATOSUS – TRANSIENT EFFECTS ON AGE ASSOCIATED B-CELLS

Background:

Immune system’s abnormalities in SLE involve several subsets of the B-cell compartment, including double negative B-cells (DN) and CD11c+CD21- B cells (also referred to as ABC-age associated B cells), which are expanded in the disease. ABC cells are also known to interact with T helper cells, T follicular and peripheral helper cells (1). Rituximab, a chimeric anti- CD20 antibody, depleting B cells, is commonly used off-label as treatment for SLE patients, especially in lupus nephritis. Little is known on the impact of B-cell depletion on such B-cell subsets and on B-T-cell interactions.

Objectives:

to investigate the effects of rituximab (RTX) on the frequencies of double negative B-cell subsets and CD11c+CD21- ABC cells and as well as T follicular helper (TFH, CXCR5+ PD-1+) and T peripheral helper (TPH, PD-1high) CD4+ T-cell subsets.

Methods:

15 SLE patients, starting RTX and followed longitudinally up to two years, were analyzed for lymphocyte subsets using multicolor flow cytometry. Cryopreserved PBMC were thawed and stained at the same time together with one buffy coat. Around 1 x 106 PBMC for each panel were labeled and further stained with fluorescent antibodies for B and T-cell markers. For the B-cell panel, PBMC were stained with anti-CD3, CD14, CD16, CD19, IgD, CD27, CD38, CD11c, CD21 and in some samples with anti-CXCR5 antibodies. For the T-cell panel, PBMC were labeled with anti-CD16, CD14, CD19 and CD3, CD4, CD8, PD-1, CCR7, CXCR5, CD45RA antibodies. All patients fulfilled the ACR 1982 classification criteria for SLE. Cellular changes were analyzed in the context of clinical information.

Results:

in the present cohort, the SLE patients were mainly female (86.6%) and of median age of 36.7 (29.8-49.4) with a disease duration of 6.1(1.6-11.8) years, and active disease with SLEDAI-2K at baseline 12.0 (8.0-16.0). The frequency of age-associated B cells (ABCs; CD27-IgD-CD11c+ CD21-) decreased by 13% (p=0.03) in the first two to four months after rituximab start, while globally the DN (IgD-CD27-) B cells transiently increased by around 3% (p=0.15) at the first follow-up. This increase could not be attributed to the DN1 (CXCR5+CD11c-) or DN2 (CXCR5-CD11c+) subsets but to the CD11c-CXCR5- DN (DN3) B cells (increase= 6.7%, p=0.03). In parallel, T effector cells (CCR7- CD45RA+) and TEMRA (CD45RA+ CCR7-) frequencies increased after first follow up in both CD4+ and CD8+ T cells. The frequency of TFH (CXCR5+ PD-1+) cells did not change after rituximab, however a decrease of PD-1high CD4+ cells was observed in most patients, although not significant, after 2-4 month of treatment. In most patients the frequency of PD-1high CD4+ cells either reduce or stay the same after RTX treatment (reduction= 0.53, p=0.28). After 11-15 months of RTX treatment the frequency of PD-1high CD4+ T cell reduces by a -0.5% in comparison to 2-4 months (p=0.039). The SLEDAI at baseline did not correlate with the frequency of PD-1high CD4+ T cells (r=0.03, p=0.9).

Conclusion:

the importance of T cell - B cell interactions in SLE pathogenesis was recently strengthened by the identification of the lymphocyte subsets TFH/TPH and ABCs respectively. Here, in the context of rituximab treated SLE, we could detect a reduction in the frequencies of both ABCs and PD-1high T cells after treatment with rituximab, while the DN3 and effector memory T cells frequencies increased. Our data suggests that anti-CD20 mediated B-cell depletion affects both B-cell and T-cell subsets frequencies, and that monitoring these specific cell subsets may be clinically relevant.

References:

[1]Bocharnikov AV, Keegan J, Wacleche VS, Cao Y, Fonseka CY, Wang G, et al. PD-1hiCXCR5- T peripheral helper cells promote B cell responses in lupus via MAF and IL-21. JCI insight. 2019;4(20)

Disclosure of Interests:

Francesca Faustini Speakers bureau: More than two years ago and not in relation to any aspect of the present research, Natalie Sippl: None declared, Ragnhild Stålesen: None declared, Karine Chemin: None declared, Iva Gunnarsson: None declared, Vivianne Malmström: None declared.

OP0072 SINGLE CELL SEQUENCING REVEALS CLONALLY EXPANDED CYTOTOXIC CD4+ T CELLS IN THE JOINTS OF ACPA+ RA PATIENTS

Background:

CD4+ T cells with cytotoxic functions (CD4+ CTL) have gained attention in recent years. Accumulating evidence supports their importance in defense against human viral infections such as CMV1, EBV2, dengue3, HIV4, 5 and SARS-CoV-26. Moreover, expansion of so called CD28null cytotoxic CD4+ T cells have been reported in the blood of patients with rheumatic diseases such as rheumatoid arthritis (RA)7, myositis8 and vasculitis9 as well as in cardiovascular diseases10.

Objectives:

Here, we aimed to investigate the presence and clonal expansion of CD4+ CTL in the peripheral blood (PB) and synovial fluid (SF) of RA patients using single cell technologies.

Methods:

We assessed the expression of cytotoxic effector molecules and transcription factors in CD4+ T cells in synovial fluid (n=21) and paired peripheral blood (n=16) from ACPA- and APCA+ RA patients by multi-parameter flow cytometry. We performed single cell sequencing, in combination with 5´ TCRab sequencing, on purified CD4+ T cells from the peripheral blood (PB) and synovial fluid (SF) of ACPA+ RA patients (n=7).

Results:

Flow cytometry experiments show that Granzyme-B+ Perforin-1+ CD4+ CTL are significantly increased in the SF of ACPA+ RA patients as compared to ACPA- RA patients (p=0.0072). The presence of CD4+ CTL could be confirmed by single cell sequencing in SF of each ACPA+ RA patient tested (n=7). Moreover, we found that the adhesion G-protein coupled receptor GPR56 is selectively expressed on the recently described peripheral helper (TPH) T-cell subset11 and associates with the expression of tissue resident memory markers LAG-3, CXCR6 and CD69. In blood, we confirmed a previous report12 showing that GPR56 delineates cytotoxic CD4+ T cells. Finally, expanded TCR clones expressing cytotoxic effector molecules were identified in synovial fluid of ACPA+ RA patients and, for some patients, in their corresponding peripheral blood.

Conclusion:

We identified GPR56 as a marker of TPH cells in SF of ACPA+ RA patients that associates with tissue residency receptors. The combination of single cell sequencing and multi-parameter flow cytometry highlights the importance of CD4+ CTL in ACPA+ RA and suggests a potential therapeutic target (Figure 1).

References:

[1]Casazza J. P. et al., J Exp Med2006,203 (13), 2865-77.

[2]Landais E. et al., Blood2004,103 (4), 1408-16.

[3]Kurane I. et al. J Exp Med1989,170 (3), 763-75.

[4]Appay V. et al. J Immunol2002,168 (11), 5954-8.

[5]Juno J. A. et al. Front Immunol2017,8, 19.

[6]Meckiff B. J. et al. Cell2020,183 (5), 1340-1353 e16.

[7]Schmidt D. et al. J Clin Invest1996,97 (9), 2027-37.

[8]Fasth A. E. et al. J Immunol2009,183 (7), 4792-9.

[9]Moosig F. et al. Clin Exp Immunol1998,114 (1), 113-8.

[10]Sato K. et al. J Exp Med2006,203 (1), 239-50.

[11]Rao D. A., et al. Nature2017,542 (7639), 110-114.

[12]Peng Y. M. et al. J Leukoc Biol2011,90 (4), 735-40.

Acknowledgements:

We thank the patients who donated samples and the medical staff at the Rheumatology Clinic of Karolinska University Hospital. Julia Boström, Gloria Rostvall, and Susana Hernandez Machado are acknowledged for organizing the sampling, storage, and administration of biomaterial. This study is supported by grants from Dr. Margaretha Nilssons, the Nanna Svartz, the Ulla and Gustaf af Ugglas foundations and the Swedish association against rheumatism.

Disclosure of Interests:

Alexandra Argyriou: None declared, Marc H Wadsworth II Employee of: Pfizer, Inc, Cambridge, MA 02139, United States, Adrian Lendvai: None declared, Stephen Christensen Employee of: Pfizer, Inc, Cambridge, MA 02139, United States, Aase Hensvold: None declared, Christina Gerstner: None declared, Kellie Kravarik Employee of: Pfizer, Inc, Cambridge, MA 02139, United States, Aaron Winkler Employee of: Pfizer, Inc, Cambridge, MA 02139, United States, Vivianne Malmström: None declared, Karine Chemin: None declared

OP0321 DELINEATING THE IMMUNOGENIC DOMAINS OF MDA5 USING PATIENT DERIVED AUTOANTIBODIES

Background:

The presence of myositis specific anti-melanoma differentiation associated protein 5 (MDA5) autoantibodies is associated with mucocutaneous ulcerations, rapidly progressing interstitial lung disease (RPILD), arthritis and mild muscle involvement in patients. RPILD is the major cause of mortality. At present it is unknown which domain of the MDA5 protein is the main elicitor of an immunogenic response.

Objectives:

The aim of this study is to delineate the domains in the MDA5 protein that are the target of autoantibodies.

Methods:

Anti-MDA5 IgG were isolated from MDA5(+) patient plasma (7 UPMC, 1 KI and 1 KULeuven) by affinity chromatography using an in-house affinity column as described earlier in Ossipova et al, 2014(1). 8 constructs covering different regions of the MDA5 protein were recombinantly produced in E.coli (Uniprot ID Q9BYX4, Figure 1). An in-house ELISA was developed to identify the domains with the main epitope(s) by measuring the reactivity of the plasma samples and purified autoantibodies against these MDA5 protein constructs, similar to what was reported by Fernandes-Cerqueira et al, 2018(2). The biotinylated MDA5 proteins were immobilized on streptavidin coated plates and subsequently incubated with primary antibodies (purified autoantibodies(2) or original plasma) and a HRP-conjugated secondary antibody. The ELISA was developed by the addition of TMB substrate and the optical density (OD) was measured at 450 nm.

Figure 1.

Graphical presentation of the constructs representing different (combinations of) domains of the MDA5 protein.

Results:

The preliminary data suggest the main reactivity of the plasma samples and the corresponding purified autoantibodies is directed towards the helicase domains and that there is variability between the patients in the reactivity towards domains located at the end of the protein.

Conclusion:

The study aims to resolve the main immunogenic domain of the MDA5 protein, which will lead to more insight in the disease mechanisms. The preliminary results suggest this domain is in the center of the MDA5 protein, but further experiments are necessary. We will use this set up to study differences in reactivity between patients (from different cohorts) and assess if differences in antibody reactivity could be linked to clinical features such as RPILD. Such correlations might be beneficial to predict the disease progression and to apply personal treatment approaches.

References:

[1]Ossipova E, Cerqueira CF, Reed E, Kharlamova N, Israelsson L, et al. Affinity purified anti-citrullinated protein/peptide antibodies target antigens expressed in the rheumatoid joint. Arthritis Res Ther. 2014;16(4):R167.

[2]Fernandes-Cerqueira C, Renard N, Notarnicola A, Wigren E, Gräslund S, et al. Patients with anti-Jo1 antibodies display a characteristic IgG Fc-glycan profile which is further enhanced in anti-Jo1 autoantibodies. Scientific reports. 2018;8(1):17958.

Disclosure of Interests:

Eveline Van Gompel: None declared, Catia Cerqueira: None declared, Edvard Wigren: None declared, Susanne Gräslund: None declared, Karine Chemin: None declared, Begum Horuluoglu: None declared, Ellen De Langhe: None declared, Olivier Benveniste: None declared, Ingrid E. Lundberg Consultant of: Consulting fees from Corbus Pharmaceuticals, Inc, Grant/research support from: Research grants from Bristol Myers Squibb and AstraZeneca.

OP0003 AUTOREACTIVE CD4+ T CELLS AND THEIR TCR REPERTOIRE IN PR3-ANCA ASSOCIATED VASCULITIS

Background:

ANCA-associated vasculitis (AAV) with proteinase 3 (PR3) ANCA is genetically associated with HLA-DP [1], is often relapsing in nature, and has a predisposition for kidneys, lungs and ear-nose-throat involvement [2]. Despite the presence of PR3+ANCA, indicating CD4+T-cell help in the disease, the knowledge about autoreactive CD4+T cells is scarce. Activated T cells have been shown at site of inflammation [3] and involvement of proinflammatory cytokines in circulation is also reported [4, 5].

Objectives:

Identification of autoreactive T cells may help to identify the drivers of the immune responses and chronicity. We therefore aimed to investigate PR3-specific CD4+T-cell responses in peripheral blood of AAV patients with a focus on both phenotype and T-cell receptor (TCR) repertoires.

Methods:

The study included sixty-six patients: 26 with active PR3 autoantibody+ AAV, 21 with inactive but PR3+ AAV and 19 with inactive PR3- AAV. In-vitro cultures with PR3 protein were established to assess antigen-specific cytokine responses in a 3-color fluorospot assay. Deep immunophenotyping was performed by flow cytometry. Antigen-responsive CD4+ T cells were isolated and single cell TCRαβ sequences were generated and analyzed from PR3+ AAV patients (n=5) using a previously published protocol [6].

Results:

PBMCs from AAV patients demonstrated an HLA-DP associated cytokine responses to PR3 stimulation including IFN-γ and IL-10, but not IL-17A. This T-cell autoreactivity was found to be confined to a highly differentiated CD4+ T cell population characterized by perforin and GPR56 expression, implicating a cytotoxic feature of the response. Active disease involved a reduction in expression of several markers associated with cytotoxicity amongst the CD4+GPR56+ T cells. Their frequency was also negatively associated with the doses of prednisolone. A similar phenotype was shared with T cells activated by human cytomegalovirus (HCMV) peptides in the same patient cohort. Single cell sequencing of paired alpha beta T-cell receptors (TCRs) revealed different patterns of gene usage between PR3 and HCMV reactive T cells. Moreover, we could identify shared (public) PR3-reactive T-cell clones between different HLA-DPB1*04:01+ patients.

Conclusion:

PR3 is an autoantigen which provokes ANCA responses in AAV patients. Our study identified PR3-reactive CD4+ T cells at the level of their phenotype and TCR repertoire. The autoreactive CD4+ T cells, present in both active and inactive disease, implicate chronic antigen exposure and the persistence of long-lived T-cell clones. The presence of public autoreactive clones between HLA-DPB1*04:01+ patients suggests an active role for these cells in pathogenesis of AAV and validates the link with predisposed genotype.

References:

[1]Lyons PA, Rayner TF, Trivedi S, Holle JU, Watts RA, Jayne DR, et al. Genetically distinct subsets within ANCA-associated vasculitis. New England Journal of Medicine. 2012; 367(3):214-223.

[2]Kumar Sharma R, Lövström B, Gunnarsson I, Malmström V. Proteinase 3 autoreactivity in Anti-Neutrophil Cytoplasmic Antibody-associated vasculitis–immunological versus clinical features. Scandinavian Journal of Immunology. 2020:e12958.

[3]Wilde B, Thewissen M, Damoiseaux J, van Paassen P, Witzke O, Tervaert JWCJAr, et al. T cells in ANCA-associated vasculitis: what can we learn from lesional versus circulating T cells? 2010; 12(1):204.

[4]Hoffmann JC, Patschan D, Dihazi H, Müller C, Schwarze K, Henze E, et al. Cytokine profiling in anti neutrophil cytoplasmic antibody-associated vasculitis: a cross-sectional cohort study. Rheumatology international. 2019; 39(11):1907-1917.

[5]Berti A, Warner R, Johnson K, Cornec D, Schroeder D, Kabat B, et al. Circulating Cytokine Profiles and ANCA Specificity in Patients with ANCA-Associated Vasculitis. Arthritis & rheumatology (Hoboken, NJ). 2018; 70(7):1114.

[6]Han A, Glanville J, Hansmann L, Davis MM. Linking T-cell receptor sequence to functional phenotype at the single-cell level. Nature biotechnology. 2014; 32(7):684-692.

Disclosure of Interests:

None declared

POS0008 IDENTIFICATION AND CHARACTERIZATION OF HISRS+ CD4+ T CELLS PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOPATHIES

Background:

Idiopathic inflammatory myopathies (IIM) also known as myositis, are rare chronic autoimmune disorders which are represented by muscle weakness and extra-muscular features such as skin rash, interstitial lung disease (ILD) and arthritis. One of the most common autoantibodies in myositis, with a prevalence of 25-35%, is the anti Jo-1 autoantibodies, targeting the histidyl-transfer RNA synthetase (HisRS). Although the exact mechanism of how these antibodies are developed is unknown, we have previously shown that upon stimulation of both peripheral blood mononuclear cells (PBMC) and bronchoalveolar lavage fluid cells (BALF) with HisRS protein, CD4+ T cells were activated and produced inflammatory cytokines. Hitherto the presence of antigen specific autoreactive T cells has not been established in myositis, however previous studies by our group showed a strong indication of their presence with a reactivity to a specific HisRS peptide.

Objectives:

The main aim of this project is to detect and characterize HisRS specific CD4+T cells using HLA Class II tetramers. HLA Class II tetramers allow the detection of rare antigen specific CD4+ T cells and are widely used in studies of immunity, vaccine development, allergy monitoring and in autoimmunity. These cells are of specific interest to understand autoimmunity and to develop new therapies in autoimmune diseases

Methods:

HLA-DRB1*03:01 monomers with selected tetanus and HisRS peptides were in-house in E.coli system. The peptides of interest were attached to the N-terminus of the HLA b-chain via a flexible peptide linker. HLA-tetramers were assembled using a commercial fluorescently labeled streptavidin. The efficacy of the peptide-HLA tetramers was validated by stimulating PBMCs from HLA-matched healthy controls with tetanus peptide. The drequency of tetanus specific CD4+ T cells were detected at different time points (6,13 and 21 days) from the cultures using tetanus peptides bound HLA-DRB1*0301 tetramers. The presence of tetanus specific T cells was confirmed by the secretion of significantly higher IFNg levels upon re-stimulation of cells with tetanus peptide. The same protocol is applied for the HisRS-peptide tetramers. Peripheral blood cells are analysed from anti-Jo1+ and HLA-DRB1*0301 positive patients with IIM.

Results:

Applying this method, our preliminary findings demonstrate the presence of HisRS+CD4+ T cells in peripheral blood from Jo-1+ patients (n=3) using HisRS tetramers following stimulation with the respective peptide. We are now including more patient samples to confirm our findings, and further characterize their phenotype and functionalities by flow cytometry and ELISA/fluorospot assays

Conclusion:

Myositis is a rare and chronic autoimmune disorder, with no currently available cure. Previous studies indicate the importance of T cells in this disease. However, the phenotype, functionality and role of these cells in the disease pathogenesis has not been fully established. Characterization of this autoreactive T-cell population will help us enhance our understanding of the disease pathogenesis and thus to develop better treatment options.

Acknowledgements:

This work has been supported by grants from Karolinska Instiutet Resarch Foundation, Professor Nanna Svartz Stiftelse, Hjärt-Lung Fonden and Vetenskapsrådet in Sweden.

Disclosure of Interests:

Begum Horuluoglu: None declared, Angeles Shunashy Galindo-Feria: None declared, Karine Chemin: None declared, Genadiy Kozhukh: None declared, Anatoly Dubnovitsky: None declared, Vivianne Malmström: None declared, Ingrid E. Lundberg Consultant of: Consulting fees from Corbus Pharmaceuticals, Ind, Grant/research support from: Research grants from Bristol Myers Squibb and Astra Zeneca.

Arthritis in systemic lupus erythematosus is characterized by local IL-17A and IL-6 expression in synovial fluid

Arthritis is a common clinical feature of systemic lupus erythematosus (SLE) and is usually non‐erosive, as opposed to rheumatoid arthritis (RA). While RA synovial pathology has been extensively studied, little is known about the pathophysiology of lupus arthritis. Here, we aimed to explore the cytokine and cellular compartments in synovial fluids of SLE patients with arthritic manifestations. Acellular synovial fluid and paired serum samples from SLE patients (n = 17) were analyzed with cytokine bead array for T helper‐associated cytokines. From two SLE patients, synovial fluid mononuclear cells (SFMC) could also be captured and were analyzed by multiparameter flow cytometry to dissect T cell, B cell, monocyte and dendritic cell phenotypes. SLE‐derived SFMC were further stimulated in vitro to measure their capacity for producing interferon (IFN)‐γ and interleukin (IL)‐17A. All patients fulfilled the ACR 1982 classification criteria for SLE. Clinical records were reviewed to exclude the presence of co‐morbidities such as osteoarthritis or overlap with RA. IL‐17A and IL‐6 levels were high in SLE synovial fluid. A clear subset of the synovial CD4⁺ T cells expressed CCR6⁺, a marker associated with T helper type 17 (Th17) cells. IL‐17A‐production was validated among CD4⁺CCR6⁺ T cells following in‐vitro stimulation. Furthermore, a strong IFN‐γ production was observed in both CD4⁺ and CD8⁺ cells. Our study shows high IL‐17A and IL‐6 levels in synovial fluids of patients with lupus arthritis. The Th17 pathway has been implicated in several aspects of SLE disease pathogenesis and our data also point to Th17 involvement for lupus arthritis.

Natural killer cells and type II interferon in Ro/SSA and La/SSB autoantibody-exposed newborns at risk of congenital heart block

OBJECTIVE

Congenital heart block (CHB) with immune cell infiltration develops in the fetus after exposure to maternal Ro/La autoantibodies. CHB-related serology has been extensively studied, but reports on immune-cell profiles of anti-Ro/La-exposed neonates are lacking. In the current study, we characterised circulating immune-cell populations in anti-Ro/La+mothers and newborns, and explored potential downstream effects of skewed neonatal cell populations.

METHODS

In total, blood from mothers (n=43) and neonates (n=66) was sampled at birth from anti-Ro/La+ (n=36) and control (n=30) pregnancies with or without rheumatic disease and CHB. Flow cytometry, microarrays and ELISA were used for characterising cells and plasma.

RESULTS

Similar to non-pregnant systemic lupus erythematosus and Sjögren-patients, anti-Ro/La+mothers had altered B-cell subset frequencies, relative T-cell lymphopenia and lower natural killer (NK)-cell frequencies. Surprisingly, their anti-Ro/La exposed neonates presented higher frequencies of CD56^dimCD16^hi NK cells (p<0.01), but no other cell frequency differences compared with controls. Type I and II interferon (IFN) gene-signatures were revealed in neonates of anti-Ro/La+ pregnancy, and exposure of fetal cardiomyocytes to type I IFN induced upregulation of several NK-cell chemoattractants and activating ligands. Intracellular flow cytometry revealed IFNγ production by NK cells, CD8⁺ and CD4⁺ T cells in anti-Ro/La exposed neonates. IFNγ was also detectable in their plasma.

CONCLUSION

Our study demonstrates an increased frequency of NK cells in anti-Ro/La exposed neonates, footprints of type I and II IFN and an upregulation of ligands activating NK cells in fetal cardiac cells after type I IFN exposure. These novel observations demonstrate innate immune activation in neonates of anti-Ro/La+pregnancy, which could contribute to the risk of CHB.

THU0046 A PIPELINE TO STUDY ANTIGEN-SPECIFIC CD4+ T CELLS IN RHEUMATOID ARTHRITIS

Background:

Autoimmunity to citrullinated autoantigens forms a critical component of disease pathogenesis in rheumatoid arthritis (RA). Presence of anti-citrullinated protein antibodies (ACPAs) in patients has high diagnostic value. Recently, several citrullinated antigen specific CD4+T cells have been described. However, detailed studies of their T-cell receptor usage and in-vivo profile suffer from the disadvantage that these cells are present at very low frequencies. In this context, we here present a pipeline for TCR repertoire analysis of antigen-specific CD4+T cells from RA patients, including both citrulline and influenza (control) specificities using in-vitro peptide challenge induced-cell expansion.

Objectives:

To enable studies of the T cell repertoire of citrullinated antigen-specific CD4+T cells in rheumatoid arthritis

Methods:

Peripheral blood mononuclear cells (PBMCs) (n=7) and synovial fluid mononuclear cells (SFMCs) (n=5) from HLA-DR*0401-postive RA patients were cultured in the presence of citrullinated Tenascin C peptide cocktails or influenza peptides (positive control). Citrulline reactive cells were further supplemented with recombinant human IL-15 and IL-7 on day 2. All cultures were replenished with fresh medium on day 6 and rIL-2 was added every 2 days from then. Assessment of proportion of peptide-HLA-tetramer positive cells was performed using flow cytometry whereby individual antigen-specific CD4+T cells were sorted into 96-well plates containing cell lysis buffer, followed by PCR-based alpha/beta TCR sequencing. TCR sequencing data was demultiplexed and aligned for TCR gene usage using MiXCR. Some tetramer positive cells were sorted into complete medium containing human IL-2 and PHA for expansion of antigen-specific cells. Cells were supplemented with irradiated allogenic PBMCs (30 times number of antigen specific cells). Clones of antigen specific CD4+T cells were further subjected to tetramer staining to confirm expansion of cells.

Results:

As evidenced by increase in frequency of tetramer positive CD4+T cells, in vitro peptide stimulation resulted in expansion of both influenza specific (Fig. 1a) and citrullinated antigen specific (Fig. 1b) CD4+T cells. Polyclonal in-vitro expansion of tenascin C tetramer positive sorted cells followed by tetramer staining further confirmed antigen specificity and enrichment for antigen specific CD4+T cells after polyclonal stimulation (Fig.1c). TCR repertoire analysis in PB and SF dataset from the first patient showed clonal expansion of influenza specific cells in both sites. Synovial fluid had more diversity of expanding clones as compared to paired PB, with few expanded clones being shared among SF and PB. We observed a more diverse TCR repertoire in citrulline specific CD4+T cells. We also observed sharing of TCR alpha chains among different citrulline specific CD4+T cell clones.

Fig. 1

In-vitroexpansion of antigen specific CD4+T cells:

Conclusion:

This method provides a highly suitable approach for investigating TCR specificities of antigen specific CD4+T cells under conditions of low cell yields. Building on this dataset will allow us to assess specific features of TCR usage of autoreactive T cells in RA.

PBMCs were cultured in presence of (a) influenza (HA, MP54) and (b) citrullinated tenascin peptides. The proportion of antigen specific CD4+T cells was assessed using HLA-class II tetramer staining. We observed an increase in frequency of (a) Infleunza specific cells (red dots in upper left and lower right quadrants) and (b) citrullinated tenascin C specific cells (red dots in lower right quadrant), at day 13 post culture as compared to day 3. (c) Sorting of citrullinated tenascin specific CD4+T cells, followed by PHA expansion resulted in visible increase in proportion of citrullinated tenascin specific CD4+T cells.

Disclosure of Interests:

Ravi kumar: None declared, Niyaz Yoosuf: None declared, Christina Gerstner: None declared, Sara Turcinov: None declared, Karine Chemin: None declared, Vivianne Malmström Grant/research support from: VM has had research grants from Janssen Pharmaceutica

Multi-HLA class II tetramer analyses of citrulline-reactive T cells and early treatment response in rheumatoid arthritis

BACKGROUND

HLA class II tetramers can be used for ex vivo enumeration and phenotypic characterisation of antigen-specific CD4+ T cells. They are increasingly applied in settings like allergy, vaccination and autoimmune diseases. Rheumatoid arthritis (RA) is a chronic autoimmune disorder for which many autoantigens have been described.

RESULTS

Using multi-parameter flow cytometry, we developed a multi-HLA class II tetramer approach to simultaneously study several antigen specificities in RA patient samples. We focused on previously described citrullinated HLA-DRB1*04:01-restricted T cell epitopes from α-enolase, fibrinogen-β, vimentin as well as cartilage intermediate layer protein (CILP). First, we examined inter-assay variability and the sensitivity of the assay in peripheral blood from healthy donors (n = 7). Next, we confirmed the robustness and sensitivity in a cohort of RA patients with repeat blood draws (n = 14). We then applied our method in two different settings. We assessed lymphoid tissue from seropositive arthralgia (n = 5) and early RA patients (n = 5) and could demonstrate autoreactive T cells in individuals at risk of developing RA. Lastly, we studied peripheral blood from early RA patients (n = 10) and found that the group of patients achieving minimum disease activity (DAS28 < 2.6) at 6 months follow-up displayed a decrease in the frequency of citrulline-specific T cells.

CONCLUSIONS

Our study demonstrates the development of a sensitive tetramer panel allowing simultaneous characterisation of antigen-specific T cells in ex vivo patient samples including RA 'at risk' subjects. This multi-tetramer approach can be useful for longitudinal immune-monitoring in any disease with known HLA-restriction element and several candidate antigens.

Effector Functions of CD4+ T Cells at the Site of Local Autoimmune Inflammation-Lessons From Rheumatoid Arthritis

Infiltration of memory CD4+ T cells in synovial joints of Rheumatoid Arthritis (RA) patients has been reported since decades. Moreover, several genome wide association studies (GWAS) pinpointing a key genetic association between the HLA-DR locus and RA have led to the generally agreed hypothesis that CD4+ T cells are directly implicated in the disease. Still, RA is a heterogeneous disease and much effort has been made to understand its different facets. T cell differentiation is driven by mechanisms including antigen stimulation, co-stimulatory signals and cytokine milieu, all of which are abundant in the rheumatic joint, implying that any T cells migrating into the joint may be further affected locally. In parallel to the characterization and classification of T-cell subsets, the contribution of different effector T cells to RA has been investigated in numerous studies though sometimes with contradictory results. In particular, the frequency of Th1 and Th17 cells has been assessed in the synovial joints with various results that could, at least partly, be explained by the stage of the disease. For regulatory T cells, it is largely accepted that they accumulate in RA synovial fluid and that the equilibrium between regulatory T cells and effector cells is a key factor in controlling inflammation processes involved in RA. Recent phenotypic studies describe the possible implication of a novel subset of peripheral T helper cells (Tph) important for T-B cell cross talk and plasma cell differentiation in the RA joint of ACPA+ (autoantibodies against citrullinated proteins) RA patients. Finally, cytotoxic CD4+ T cells, historically described as increased in the peripheral blood of RA patients have attracted new attention in the last years. In view of the recently identified peripheral T-cell subsets, we will integrate immunological data as well as information on genetic variants and therapeutic strategy outcomes into our current understanding of the width of effector T cells. We will also integrate tissue-resident memory T cell aspects, and discuss similarities and differences with inflammatory conditions in skin (psoriasis) and mucosal organs (Crohn's disease).

Tooth Sensitivity After Dental Bleaching With a Desensitizer-containing and a Desensitizer-free Bleaching Gel: A Systematic Review and Meta-analysis

Objectives:

A systematic review and meta-analysis were performed to evaluate the risk and intensity of tooth sensitivity (TS) after dental bleaching with a desensitizer-containing and a desensitizer-free bleaching gel in adult patients. Color change and risk of gingival sensitivity was also evaluated.

Methods:

A comprehensive search was performed MEDLINE via PubMed, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database (LILACS), Brazilian Library in Dentistry (BBO), EMBASE and Cochrane Library, and System for Information on Grey Literature in Europe (SIGLE) without restrictions to identify randomized clinical trials. Abstracts from the annual conference of the International Association for Dental Research (1990–2016), unpublished and ongoing trials registries, dissertations, and theses were also searched. The quality of the evidence was rated using the Grading of Recommendations: Assessment, Development and Evaluation (GRADE) approach.

Data:

After duplicates were removed, 1352 articles were identified. After title and abstract screening, only 47 studies remained for qualitative evaluation. Most of the studies had unclear risk of bias. No difference between groups were observed for the risk ratio of TS (risk ratio = 0.99; 95% confidence interval [CI] = 0.74–1.33); intensity of TS (standardized difference in means [SMD] = 0.04; 95% CI = 0.79–0.70); color change in shade guide units (SMD – 0.04; 95% CI = 0.50–0.42); color change in ΔE* (SMD = 0.41 (95% CI = 0.07–0.89); and risk ratio of gingival irritation (SMD = 1.05; 95% CI = 0.81–1.36). Except for the risk of TS, graded as moderate quality of evidence, all other outcomes were rated as low and very low quality.

Conclusions:

Incorporating desensitizers in the bleaching gel did not reduce the risk of TS, and the quality of this evidence was considered moderate. On the other hand, the intensity of TS, color change, and risk of gingival irritation was similar between groups, but the quality of the evidence for these outcomes was graded as low or very low, thus reducing the level of confidence in these outcomes.

FoxP3+ CXCR5+ CD4+ T cell frequencies are increased in peripheral blood of patients with primary Sjögren's syndrome

We recently explored the expression of CXCR5 on T and B cells from peripheral blood of patients with primary Sjögren's syndrome (SS). Here we investigated the frequency of CD25⁺ FoxP3⁺ CD4⁺ regulatory T cells (T_regs ) among CXCR5⁺ CD4⁺ follicular cells in the same cohort of patients. We confirm that the frequency of T_regs among follicular T cells is increased in SS patients and also provide novel data showing an increased frequency of PD-1 expressing cells among CXCR5⁺ FoxP3⁺ CD4⁺ T cells.

Differential ACPA Binding to Nuclear Antigens Reveals a PAD-Independent Pathway and a Distinct Subset of Acetylation Cross-Reactive Autoantibodies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) associated anti-citrullinated protein autoantibodies (ACPA) target a wide range of modified proteins. Citrullination occurs during physiological processes such as apoptosis, yet little is known about the interaction of ACPA with nuclear antigens or apoptotic cells. Since uncleared apoptotic cells and neutrophil extracellular trap (NET) products have been postulated to be central sources of autoantigen and immunostimulation in autoimmune disease, we sought to characterize the anti-nuclear and anti-neutrophil reactivities of ACPA. Serology showed that a subset of anti-CCP2 seropositive RA patients had high reactivity to full-length citrullinated histones. In contrast, seronegative RA patients displayed elevated IgG reactivity to native histone compared to controls, but no citrulline-specific reactivity. Screening of 10 single B-cell derived monoclonal ACPA from RA patients revealed that four ACPA exhibited strong binding to apoptotic cells and three of these had anti-nuclear (ANA) autoantibody reactivity. Modified histones were confirmed to be the primary targets of this anti-nuclear ACPA subset following immunoprecipitation from apoptotic cell lysates. Monoclonal ACPA were also screened for reactivities against stimulated murine and human neutrophils, and all the nuclear-reactive monoclonal ACPA bound to NETs. Intriguingly, one ACPA mAb displayed a contrasting cytoplasmic perinuclear neutrophil binding and may represent a different NET-reactive ACPA subset. Notably, studies of CRISPR-Cas9 PAD4 KO cells and cells from PAD KO mice showed that the cytoplasmic NET-binding was fully dependent on PAD4, whilst nuclear- and histone-mediated NET reactivity was largely PAD-independent. Our further analysis revealed that the nuclear binding could be explained by consensus-motif driven ACPA cross-reactivity to acetylated histones. Specific acetylated histone peptides targeted by the monoclonal antibodies were identified and the anti-modified protein autoantibody (AMPA) profile of the ACPA was found to correlate with the functional activity of the antibodies. In conclusion, when investigating monoclonal ACPA, we could group ACPA into distinct subsets based on their nuclear binding-patterns and acetylation-mediated binding to apoptotic cells, neutrophils, and NETs. Differential anti-modified protein reactivities of RA-autoantibody subsets could have an important functional impact and provide insights in RA pathogenesis.

Effectiveness of and Dental Sensitivity to At-home Bleaching With 4% and 10% Hydrogen Peroxide: A Randomized, Triple-blind Clinical Trial

OBJECTIVES

To evaluate the risk for and intensity of tooth sensitivity and color change of at-home dental bleaching with 4% and 10% hydrogen peroxide (HP).

METHODS

For this study, 78 patients were selected according to the inclusion and exclusion criteria and randomized into two groups: HP 4 (White Class 4%, FGM) and HP 10 (White Class 10%, FGM). In both groups, the at-home bleaching was performed for a period of 30 minutes twice a day for two weeks. The color was assessed by Vita Classical, Vita Bleachedguide 3D-MASTER and spectrophotometer Vita Easyshade (Vita Zahnfabrik) at baseline, during bleaching (first and second weeks) and after bleaching (one month). Patients recorded their tooth sensitivity using a numeric rating scale (0-4) and visual analog scale (0-10). Data from color change (DeltaE data) was submitted to two-way analysis of variance. The color change data in Delta SGU from the two shade guide units were compared with the Mann Whitney test. The risk of tooth sensitivity was evaluated by χ² test and the intensity of tooth sensitivity from both scales was evaluated by a Mann-Whitney test (α=0.05).

RESULTS

The absolute risk and intensity of tooth sensitivity was higher in the group that used HP 10 than the one that used HP 4. Data from change in the number of shade guide units and color variation after one month of bleaching for both groups showed significant whitening, with no difference between groups.

CONCLUSIONS

At-home bleaching is effective with 4% and 10% HP concentrations, but 10% HP increased the absolute risk and intensity of tooth sensitivity during at-home bleaching.

T-cell transcriptomics from peripheral blood highlights differences between polymyositis and dermatomyositis patients

BACKGROUND

Polymyositis (PM) and dermatomyositis (DM) are two distinct subgroups of idiopathic inflammatory myopathies, a chronic inflammatory disorder clinically characterized by muscle weakness and inflammatory cell infiltrates in muscle tissue. In PM, a major component of inflammatory cell infiltrates is CD8+ T cells, whereas in DM, CD4+ T cells, plasmacytoid dendritic cells, and B cells predominate. In this study, with the aim to differentiate involvement of CD4+ and CD8+ T-cell subpopulations in myositis subgroups, we investigated transcriptomic profiles of T cells from peripheral blood of patients with myositis.

METHODS

Total RNA was extracted from CD4+ T cells (PM = 8 and DM = 7) and CD8+ T cells (PM = 4 and DM = 5) that were isolated from peripheral blood mononuclear cells via positive selection using microbeads. Sequencing libraries were generated using the Illumina TruSeq Stranded Total RNA Kit and sequenced on an Illumina HiSeq 2500 platform, yielding about 50 million paired-end reads per sample. Differential gene expression analyses were conducted using DESeq2.

RESULTS

In CD4+ T cells, only two genes, ANKRD55 and S100B, were expressed significantly higher in patients with PM than in patients with DM (false discovery rate [FDR] < 0.05, model adjusted for age, sex, HLA-DRB1*03 status, and RNA integrity number [RIN]). On the contrary, in CD8+ T cells, 176 genes were differentially expressed in patients with PM compared with patients with DM. Of these, 44 genes were expressed significantly higher in CD8+ T cells from patients with PM, and 132 genes were expressed significantly higher in CD8+ T cells from patients with DM (FDR < 0.05, model adjusted for age, sex, and RIN). Gene Ontology analysis showed that genes differentially expressed in CD8+ T cells are involved in lymphocyte migration and regulation of T-cell differentiation.

CONCLUSIONS

Our data strongly suggest that CD8+ T cells represent a major divergence between PM and DM patients compared with CD4+ T cells. These alterations in the gene expression in T cells from PM and DM patients might advocate for distinct immune mechanisms in these subphenotypes of myositis.

Systematic approach demonstrates enrichment of multiple interactions between non-HLA risk variants and HLA-DRB1 risk alleles in rheumatoid arthritis

OBJECTIVE

In anti-citrullinated protein antibody positive rheumatoid arthritis (ACPA-positive RA), a particular subset of HLA-DRB1 alleles, called shared epitope (SE) alleles, is a highly influential genetic risk factor. Here, we investigated whether non-HLA single nucleotide polymorphisms (SNP), conferring low disease risk on their own, interact with SE alleles more frequently than expected by chance and if such genetic interactions influence the HLA-DRB1 SE effect concerning risk to ACPA-positive RA.

METHODS

We computed the attributable proportion (AP) due to additive interaction at genome-wide level for two independent ACPA-positive RA cohorts: the Swedish epidemiological investigation of rheumatoid arthritis (EIRA) and the North American rheumatoid arthritis consortium (NARAC). Then, we tested for differences in the AP p value distributions observed for two groups of SNPs, non-associated and associated with disease. We also evaluated whether the SNPs in interaction with HLA-DRB1 were cis-eQTLs in the SE alleles context in peripheral blood mononuclear cells from patients with ACPA-positive RA (SE-eQTLs).

RESULTS

We found a strong enrichment of significant interactions (AP p<0.05) between the HLA-DRB1 SE alleles and the group of SNPs associated with ACPA-positive RA in both cohorts (Kolmogorov-Smirnov test D=0.35 for EIRA and D=0.25 for NARAC, p<2.2e-16 for both). Interestingly, 564 out of 1492 SNPs in consistent interaction for both cohorts were significant SE-eQTLs. Finally, we observed that the effect size of HLA-DRB1 SE alleles for disease decreases from 5.2 to 2.5 after removal of the risk alleles of the two top interacting SNPs (rs2476601 and rs10739581).

CONCLUSION

Our data demonstrate that there are massive genetic interactions between the HLA-DRB1 SE alleles and non-HLA genetic variants in ACPA-positive RA.

Diminished CXCR5 expression in peripheral blood of patients with Sjögren's syndrome may relate to both genotype and salivary gland homing

Genetic investigations of Sjögren's syndrome (SS) have identified a susceptibility locus at p23.3 of chromosome 11, which contains the CXCR5 gene. C-X-C motif chemokine receptor 5 (CXCR5) is a chemokine receptor expressed on B and T cell subsets, and binds the chemotactic ligand C-X-C motif chemokine ligand 13 (CXCL13). In this study we aimed to link the genetic association with functional effects and explore the CXCR5/CXCL13 axis in SS. Expression quantitative trait loci analysis of the 11q23.3 locus was performed using B cell mRNA expression data from genotyped individuals. Lymphocyte surface markers were assessed by flow cytometry, and CXCL13 levels by a proximity extension assay. CXCR5+ and CXCL13+ cells in minor salivary glands were detected using immunohistochemistry. Our results demonstrated that SS-associated genetic polymorphisms affected the expression of CXCR5 (P < 0·01). Notably, a decreased percentage of CXCR5+ cells, with lower CXCR5 expression, was observed for most circulating B and T cell subsets in SS patients, reaching statistical significance in CD19+ CD27+ immunoglobulin (Ig)D+ marginal zone (P < 0·001), CD19+ CD27+ IgD- memory (P < 0·05) and CD27-IgD double-negative (P < 0·01) B cells and CD4+ CXCR3- CCR6+ Th17 cells (P < 0·05). CXCL13 levels were increased in patient plasma (P < 0·001), and immunohistochemical staining revealed expression of CXCL13 and higher numbers of CXCR5+ cells (P < 0·0001) within focal infiltrates and interstitially in salivary glands of SS patients. In conclusion, we link a genetic susceptibility allele for SS to a functional phenotype in terms of decreased CXCR5 expression. The decrease of CXCR5+ cells in circulation was also related to homing of B and T cells to the autoimmune target organ. Therapeutic drugs targeting the CXCR5/CXCL13 axis may be useful in SS.

EOMES-positive CD4+ T cells are increased in PTPN22 (1858T) risk allele carriers

The presence of the PTPN22 risk allele (1858T) is associated with several autoimmune diseases including rheumatoid arthritis (RA). Despite a number of studies exploring the function of PTPN22 in T cells, the exact impact of the PTPN22 risk allele on T-cell function in humans is still unclear. In this study, using RNA sequencing, we show that, upon TCR-activation, naïve human CD4⁺ T cells homozygous for the PTPN22 risk allele overexpress a set of genes including CFLAR and 4-1BB, which are important for cytotoxic T-cell differentiation. Moreover, the protein expression of the T-box transcription factor Eomesodermin (EOMES) was increased in T cells from healthy donors homozygous for the PTPN22 risk allele and correlated with a decreased number of naïve CD4⁺ T cells. There was no difference in the frequency of other CD4⁺ T-cell subsets (Th1, Th17, Tfh, Treg). Finally, an accumulation of EOMES⁺ CD4⁺ T cells was observed in synovial fluid of RA patients with a more pronounced production of Perforin-1 in PTPN22 risk allele carriers. Altogether, we propose a novel mechanism of action of PTPN22 risk allele through the generation of cytotoxic CD4⁺ T cells and identify EOMES⁺ CD4⁺ T cells as a relevant T-cell subset in RA pathogenesis.

T cells are influenced by a long non-coding RNA in the autoimmune associated PTPN2 locus

Non-coding SNPs in the protein tyrosine phosphatase non-receptor type 2 (PTPN2) locus have been linked with several autoimmune diseases, including rheumatoid arthritis, type I diabetes, and inflammatory bowel disease. However, the functional consequences of these SNPs are poorly characterized. Herein, we show in blood cells that SNPs in the PTPN2 locus are highly correlated with DNA methylation levels at four CpG sites downstream of PTPN2 and expression levels of the long non-coding RNA (lncRNA) LINC01882 downstream of these CpG sites. We observed that LINC01882 is mainly expressed in T cells and that anti-CD3/CD28 activated naïve CD4⁺ T cells downregulate the expression of LINC01882. RNA sequencing analysis of LINC01882 knockdown in Jurkat T cells, using a combination of antisense oligonucleotides and RNA interference, revealed the upregulation of the transcription factor ZEB1 and kinase MAP2K4, both involved in IL-2 regulation. Overall, our data suggests the involvement of LINC01882 in T cell activation and hints towards an auxiliary role of these non-coding SNPs in autoimmunity associated with the PTPN2 locus.

A Novel HLA-DRB1*10:01-Restricted T Cell Epitope From Citrullinated Type II Collagen Relevant to Rheumatoid Arthritis

OBJECTIVE

Antibodies against citrullinated type II collagen (Cit-CII) are common in the sera and synovial fluid of patients with rheumatoid arthritis (RA); however, the known T cell epitope of CII is not dependent on citrullination. The aim of this study was to identify and functionally characterize the Cit-CII-restricted T cell epitopes that are relevant to RA.

METHODS

Peripheral blood mononuclear cells (PBMCs) from HLA-DRB1*10:01-positive patients with RA and healthy donors were stimulated in vitro with candidate CII peptides. CD154 up-regulation was measured as a marker of antigen-specific activation, and anti-HLA-DR-blocking experiments confirmed HLA restriction. Cytokine production was measured using a Luminex technique. Direct peptide-binding assays using HLA-DRB1*10:01 and HLA-DRB1*04:01 monomeric proteins were performed. The T cell receptor (TCR) β-chain of CD154-enriched antigen-specific T cells was analyzed using high-throughput sequencing.

RESULTS

A novel Cit-CII peptide was identified based on its ability to activate CD4+ T cells from HLA-DRB1*10:01-positive individuals. When stimulated in vitro, Cit-CII autoreactive T cells produced proinflammatory cytokines. Cit-CII(311-325) bound (with low affinity) to HLA-DRB1*10:01 but not to HLA-DRB1*04:01, while the native form was unable to bind either protein. In addition, highly expanded clones were identified in the TCRβ repertoire of Cit-CII(311-325) -stimulated PBMCs.

CONCLUSION

These results illustrate the ability of the citrullination process to create T cell epitopes from CII, a cartilage-restricted protein that is relevant to RA pathogenesis. The exclusive binding of Cit-CII(311-325) to HLA-DRB1*10:01 suggests that recognition of citrullinated epitopes might vary between individuals carrying different RA-associated HLA-DR molecules.

Development of autoantibodies against muscle-specific FHL1 in severe inflammatory myopathies

Mutations of the gene encoding four-and-a-half LIM domain 1 (FHL1) are the causative factor of several X-linked hereditary myopathies that are collectively termed FHL1-related myopathies. These disorders are characterized by severe muscle dysfunction and damage. Here, we have shown that patients with idiopathic inflammatory myopathies (IIMs) develop autoimmunity to FHL1, which is a muscle-specific protein. Anti-FHL1 autoantibodies were detected in 25% of IIM patients, while patients with other autoimmune diseases or muscular dystrophies were largely anti-FHL1 negative. Anti-FHL1 reactivity was predictive for muscle atrophy, dysphagia, pronounced muscle fiber damage, and vasculitis. FHL1 showed an altered expression pattern, with focal accumulation in the muscle fibers of autoantibody-positive patients compared with a homogeneous expression in anti-FHL1-negative patients and healthy controls. We determined that FHL1 is a target of the cytotoxic protease granzyme B, indicating that the generation of FHL1 fragments may initiate FHL1 autoimmunity. Moreover, immunization of myositis-prone mice with FHL1 aggravated muscle weakness and increased mortality, suggesting a direct link between anti-FHL1 responses and muscle damage. Together, our findings provide evidence that FHL1 may be involved in the pathogenesis not only of genetic FHL1-related myopathies but also of autoimmune IIM. Importantly, these results indicate that anti-FHL1 autoantibodies in peripheral blood have promising potential as a biomarker to identify a subset of severe IIM.

Surface expression of CD39 identifies an enriched Treg-cell subset in the rheumatic joint, which does not suppress IL-17A secretion

Treg cells are important for the maintenance of self-tolerance and are implicated in autoimmunity. Despite enrichment of Treg cells in joints of rheumatoid arthritis (RA) patients, local inflammation persists. As expression of the ATP-hydrolyzing enzymes CD39 and CD73 and the resulting anti-inflammatory adenosine production have been implicated as an important mechanism of suppression, we characterized FOXP3(+) Treg cells in blood and synovial fluid samples of RA patients in the context of CD39 and CD73 expression. Synovial FOXP3(+) Treg cells displayed high expression levels of rate-limiting CD39, whereas CD73 was diminished. FOXP3(+) CD39(+) Treg cells were also abundant in synovial tissue. Furthermore, FOXP3(+) CD39(+) Treg cells did not secrete the proinflammatory cytokines IFN-γ and TNF after in vitro stimulation in contrast to FOXP3(+) CD39(-) T cells. FOXP3(+) CD39(+) Treg cells could be isolated by CD39 and CD25 coexpression, displayed a demethylated Treg-specific demethylated region and coculture assays confirmed that CD25(+) CD39(+) T cells have suppressive capacity, while their CD39(-) counterparts do not. Overall, our data show that FOXP3(+) CD39(+) Treg cells are enriched at the site of inflammation, do not produce proinflammatory cytokines, and are good suppressors of many effector T-cell functions including production of IFN-γ, TNF, and IL-17F but do not limit IL-17A secretion.

Cytokine secretion by CD4+ T cells at the immunological synapse requires Cdc42-dependent local actin remodeling but not microtubule organizing center polarity

Cytokine secretion by T lymphocytes plays a central role in mounting adaptive immune responses. However, little is known about how newly synthesized cytokines, once produced, are routed within T cells and about the mechanisms involved in regulating their secretions. In this study, we investigated the role of cytoskeleton remodeling at the immunological synapse (IS) in cytokine secretion. We show that a key regulator of cytoskeleton remodeling, the Rho GTPase Cdc42, controls IFN-γ secretion by primary human CD4+ T lymphocytes. Surprisingly, microtubule organizing center polarity at the IS, which does not depend on Cdc42, is not required for cytokine secretion by T lymphocytes, whereas microtubule polymerization is required. In contrast, actin remodeling at the IS, which depends on Cdc42, controls the formation of the polymerized actin ring at the IS, the dynamic concentration of IFN-γ-containing vesicles inside this ring, and the secretion of these vesicles. These results reveal a previously unidentified role of Cdc42-dependent actin remodeling in cytokine exocytosis at the IS.

Force generation upon T cell receptor engagement

T cells are major players of adaptive immune response in mammals. Recognition of an antigenic peptide in association with the major histocompatibility complex at the surface of an antigen presenting cell (APC) is a specific and sensitive process whose mechanism is not fully understood. The potential contribution of mechanical forces in the T cell activation process is increasingly debated, although these forces are scarcely defined and hold only limited experimental evidence. In this work, we have implemented a biomembrane force probe (BFP) setup and a model APC to explore the nature and the characteristics of the mechanical forces potentially generated upon engagement of the T cell receptor (TCR) and/or lymphocyte function-associated antigen-1 (LFA-1). We show that upon contact with a model APC coated with antibodies towards TCR-CD3, after a short latency, the T cell developed a timed sequence of pushing and pulling forces against its target. These processes were defined by their initial constant growth velocity and loading rate (force increase per unit of time). LFA-1 engagement together with TCR-CD3 reduced the growing speed during the pushing phase without triggering the same mechanical behavior when engaged alone. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was monitored simultaneously to verify the cell commitment in the activation process. [Ca(2+)](i) increased a few tens of seconds after the beginning of the pushing phase although no strong correlation appeared between the two events. The pushing phase was driven by actin polymerization. Tuning the BFP mechanical properties, we could show that the loading rate during the pulling phase increased with the target stiffness. This indicated that a mechanosensing mechanism is implemented in the early steps of the activation process. We provide here the first quantified description of force generation sequence upon local bidimensional engagement of TCR-CD3 and discuss its potential role in a T cell mechanically-regulated activation process.

T cell polarity at the immunological synapse is required for CD154-dependent IL-12 secretion by dendritic cells

Ag-specific interaction between T lymphocytes and dendritic cells (DCs) leads to both T cell and DC activation. CD154 (CD40 ligand)/CD40 interactions have been shown to play a major, although not exclusive, role in this functional cross-talk. Interactions between T cells and DCs are structured by an immunological synapse (IS), characterized by polarization of the T cell microtubule cytoskeleton toward the interacting DCs. Yet the role T cell polarization may play in T cell-induced DC activation is mostly unknown. In this study, we address the role of T cell polarity in CD154-dependent activation of DCs in a human model, using two different tools to block T cell polarity (i.e., a microtubule depolymerizing drug and an inhibitor of atypical protein kinase C). We show that CD154 is recruited and concentrated at the IS formed between human primary T cells and autologous DCs and that this recruitment requires T cell polarity at the IS. Moreover, we show that T cell polarization at the IS controls T cell-dependent CD154-CD40 signaling in DCs as well as CD154-dependent IL-12 secretion by DCs. This study shows that T cell polarity at the IS plays a key role in CD154/CD40-dependent cross-talk between CD4(+) T cells and DCs.

The Ets-1 transcription factor controls the development and function of natural regulatory T cells

Regulatory T cells (T reg cells) constitute a population of CD4(+) T cells that limits immune responses. The transcription factor Foxp3 is important for determining the development and function of T reg cells; however, the molecular mechanisms that trigger and maintain its expression remain incompletely understood. In this study, we show that mice deficient for the Ets-1 transcription factor (Ets-1(-/-)) developed T cell-mediated splenomegaly and systemic autoimmunity that can be blocked by functional wild-type T reg cells. Spleens of Ets-1(-/-) mice contained mostly activated T cells, including Th2-polarized CD4(+) cells and had reduced percentages of T reg cells. Splenic and thymic Ets-1(-/-) T reg cells expressed low levels of Foxp3 and displayed the CD103 marker that characterizes antigen-experienced T reg cells. Thymic development of Ets-1(-/-) T reg cells appeared intrinsically altered as Foxp3-expressing cells differentiate poorly in mixed fetal liver reconstituted chimera and fetal thymic organ culture. Ets-1(-/-) T reg cells showed decreased in vitro suppression activity and did not protect Rag2(-/-) hosts from naive T cell-induced inflammatory bowel disease. Furthermore, in T reg cells, Ets-1 interacted with the Foxp3 intronic enhancer and was required for demethylation of this regulatory sequence. These data demonstrate that Ets-1 is required for the development of natural T reg cells and suggest a role for this transcription factor in the regulation of Foxp3 expression.

Detection and follow-up of fibroblast growth factor receptor 3 expression on bone marrow and circulating plasma cells by flow cytometry in patients with t(4;14) multiple myeloma

The t(4;14)(p16;q32) translocation, found in 15% of multiple myeloma (MM) cases, indicates a poor prognosis. Plasma cells (PC) with t(4;14) ectopically express the fibroblast growth factor receptor 3 (FGFR3) tyrosine kinase receptor, which has potential transforming activity and may represent a therapeutic target. To detect FGFR3 protein expression, bone marrow (BM) aspirate from 200 consecutive newly diagnosed (n = 116) or relapsing (n = 74) MM patients was studied by flow cytometry (FC) using anti-CD138 and anti-FGFR3 antibodies. FC data was compared to real time quantitative-polymerase chain reaction (RQ-PCR) of the IGH-MMSET and FGFR3 transcripts. An IGH-MMSET transcript was found in 24/200 patients (12%). In 20 of these, FC detected CD138(+)/FGFR3(+) cells. No expression of FGFR3 was detected in the 4 FGFR3(-) cases by RQ-PCR. FGFR3 was never expressed on PC without t(4;14). Circulating PC (CPC) were detected in patients with (11/11) and patients without (13/41) t(4;14). In 2/8 t(4;14) cases studied longitudinally, coexisting FGFR3(+) and FGFR3(-) CPC were observed. Fluorescent in situ hybridisation (FISH) analysis of the FGFR3(-) subclones showed deletion of the der(14) in one patient. In conclusion, as a supplemental method to RQ-PCR or FISH, FC analysis of FGFR3 expression is a reliable and routinely available method for the detection and management of new therapeutic approaches of t(4;14) MM.

Identification, activation, and selective in vivo ablation of mouse NK cells via NKp46

Natural killer (NK) cells contribute to a variety of innate immune responses to viruses, tumors and allogeneic cells. However, our understanding of NK cell biology is severely limited by the lack of consensus phenotypic definition of these cells across species, by the lack of specific marker to visualize them in situ, and by the lack of a genetic model where NK cells may be selectively ablated. NKp46/CD335 is an Ig-like superfamily cell surface receptor involved in human NK cell activation. In addition to human, we show here that NKp46 is expressed by NK cells in all mouse strains analyzed, as well as in three common monkey species, prompting a unifying phenotypic definition of NK cells across species based on NKp46 cell surface expression. Mouse NKp46 triggers NK cell effector function and allows the detection of NK cells in situ. NKp46 expression parallels cell engagement into NK differentiation programs because it is detected on all NK cells from the immature CD122(+)NK1.1(+)DX5(-) stage and on a minute fraction of NK-like T cells, but not on CD1d-restricted NKT cells. Moreover, human NKp46 promoter drives NK cell selective expression both in vitro and in vivo. Using NKp46 promoter, we generated transgenic mice expressing EGFP and the diphtheria toxin (DT) receptor in NK cells. DT injection in these mice leads to a complete and selective NK cell ablation. This model paves a way for the in vivo characterization and preclinical assessment of NK cell biological function.

Distinct and overlapping roles of interleukin-10 and CD25+ regulatory T cells in the inhibition of antitumor CD8 T-cell responses

Lack of antitumor immunity is often related to impaired CD8 T-cell responses that could result from a poor priming capacity by tumor-infiltrating dendritic cells (TIDC) and/or further inhibition by regulatory T cells (T(reg)). Interleukin-10 (IL-10) has been implicated in the inhibition of TIDC as well as in the generation and functions of T(reg). Here, we address some of the respective and possibly overlapping roles of IL-10 and CD25+ T(reg) in CD8 antitumor immunity. Whereas tumor antigen-specific CD8 T cells proliferated in vivo in the presence of IL-10 or T(reg), optimal effector functions were observed in mice lacking both IL-10 and T(reg). Indeed, tumors grown in normal but not in IL-10-deficient or CD25-depleted mice induced tumor antigen-specific CD8 suppressor T cells. Suppression involved transforming growth factor-beta. Similarly, both IL-10 and T(reg) were responsible for impaired CD8 T cell priming by TIDCs, but IL-12 production by TIDCs was prevented only by T(reg)-independent IL-10. Subsequently, IL-10 defect and T(reg) depletion were required to achieve optimal induction of CD8 T-cell effectors by TIDC following CpG activation. Our results point out major redundant and nonredundant roles for IL-10 and T(reg) in the inhibition of TIDC-mediated generation of antitumor CD8 T-cell response.

Type I interferon dependence of plasmacytoid dendritic cell activation and migration

Differential expression of Toll-like receptor (TLR) by conventional dendritic cells (cDCs) and plasmacytoid DC (pDCs) has been suggested to influence the type of immune response induced by microbial pathogens. In this study we show that, in vivo, cDCs and pDCs are equally activated by TLR4, -7, and -9 ligands. Type I interferon (IFN) was important for pDC activation in vivo in response to all three TLR ligands, whereas cDCs required type I IFN signaling only for TLR9- and partially for TLR7-mediated activation. Although TLR ligands induced in situ migration of spleen cDC into the T cell area, spleen pDCs formed clusters in the marginal zone and in the outer T cell area 6 h after injection of TLR9 and TLR7 ligands, respectively. In vivo treatment with TLR9 ligands decreased pDC ability to migrate ex vivo in response to IFN-induced CXCR3 ligands and increased their response to CCR7 ligands. Unlike cDCs, the migration pattern of pDCs required type I IFN for induction of CXCR3 ligands and responsiveness to CCR7 ligands. These data demonstrate that mouse pDCs differ from cDCs in the in vivo response to TLR ligands, in terms of pattern and type I IFN requirement for activation and migration.

The development of early and mature B?cells is impaired in mice deficient for the Ets-1 transcription factor

The Ets-1 transcription factor is essential for normal development of the natural killer and T cell lineages; however, its role in B cell development remains poorly understood. To address this issue, we used gene targeting to inactivate Ets-1 in mice (Ets-1(-/-)). We show here that the development of B cell precursors, particularly steps requiring pre-B cell receptor function, is defective in Ets-1(-/-) mice. Peripheral B cell subsets were analyzed in RAG2-deficient mice reconstituted with Ets-1(-/-) fetal liver cells. In such Ets-1(-/-) chimeric mice, B cell precursors develop into IgM/IgD-bearing cells, but B-1a cells as well as transitional-2 and marginal zone B cell subsets of the spleen are absent. In response to B cell receptor stimulation, Ets-1(-/-) splenic B cells fail to express the CD69 and CD25 activation markers. Furthermore, despite activation of ERK and JNK signaling pathways, Ets-1-deficient B cells do not proliferate and die following BCR engagement. These findings demonstrate that the effect of Ets-1 inactivation is not restricted to the terminal B cell differentiation stage, but also affects the development and function of earlier B cell subsets.

The Ets-1 transcription factor is required for complete pre-T cell receptor function and allelic exclusion at the T cell receptor beta locus

The pre-T cell receptor (TCR) functions as a critical checkpoint during alphabeta T cell development. Signaling through the pre-TCR controls the differentiation of immature CD4(-)CD8(-)CD25(+)CD44(-) [double-negative (DN)3] thymocytes into CD4(+)CD8(+) double-positive (DP) cells through the CD4(-)CD8(-)CD25(-)CD44(-)(DN4) stage. In addition, pre-TCR activity triggers expansion and survival of thymocytes and inhibits TCRbeta gene rearrangement through a process referred to as allelic exclusion. Whereas many proteins involved in the pre-TCR transduction cascade have been identified, little is known about the nuclear factors associated with receptor function. Here, we use gene targeting to inactivate the Ets-1 transcription factor in mice and analyze pre-TCR function in developing Ets-1-deficient (Ets-1(-/-)) thymocytes. We find that inactivation of Ets-1 impairs the development of DN3 into DP thymocytes and induces an elevated rate of cell death in the DN4 subset. This defect appears specific to the alphabeta lineage because gammadelta T cells maturate efficiently. Finally, the percentage of thymocytes coexpressing two different TCRbeta chains is increased in the Ets-1(-/-) background and, in contrast with wild type, forced activation of pre-TCR signaling does not block endogenous TCRbeta gene rearrangement. These data identify Ets-1 as a critical transcription factor for pre-TCR functioning and for allelic exclusion at the TCRbeta locus.

Lactobacillus casei reduces CD8+ T cell-mediated skin inflammation

Probiotics, including Lactobacilli, have been postulated to alleviate allergic and inflammatory diseases, but evidence that they exert an anti-inflammatory effect by immune modulation of pathogenic T cell effectors is still lacking. The aim of this study was to examine whether L. casei could affect antigen-specific T cell-mediated skin inflammation. To this end, we used contact hypersensitivity to the hapten 2,4-dinitrofluorobenzene, a model of allergic contact dermatitis mediated by CD8+ CTL and controlled by CD4+ regulatory T cells. Daily oral administration of fermented milk containing L. casei or L. casei alone decreased skin inflammation by inhibiting the priming/expansion of hapten-specific IFN-gamma-producing CD8+ effector T cells. The down-regulatory effect of the probiotics required the presence of CD4+ T cells, which control the size of the hapten-specific CD8+ T cell pool primed by skin sensitization. L. casei cell wall was as efficient as live L. casei to regulate both the CHS response and the hapten-specific CD8+ T cell response, suggesting that cell wall components contribute to the immunomodulatory effect of L. casei. This study provides the first evidence that oral administration of L. casei can reduce antigen-specific skin inflammation by controlling the size of the CD8+ effector pool.

Regulation of dendritic cell recruitment by chemokines

Dendritic cells (DC) are a heterogeneous family of cells that function as sentinels of the immune system. This article summarizes observations suggesting that inflammatory chemokines secreted at the site of pathogen invasion determine the DC subset recruited and influence the class of the immune response initiated. Langerhans cells are selectively recruited by MIP-3alpha/CCL20. In contrast, CCR7 ligands have a key role in the accumulation of antigen-loaded mature DC in T cell-rich areas of the draining lymph node. Improved understanding of the regulation of DC trafficking might offer new opportunities for therapeutic interventions to control immune responses.

Measles virus exploits dendritic cells to suppress CD4+ T-cell proliferation via expression of surface viral glycoproteins independently of T-cell trans-infection

Dendritic cells (DC) have been proposed to play a pivotal role in transient immune suppression induced by measles virus (MV) infection. In the present study, we show that DC-induced suppression of T-cell proliferation was not mediated by IL-10 or IFNalpha/beta, which are released following infection of DC, but required cell contacts between MV-infected DC and T cells. Human sera containing neutralizing anti-MV antibodies, as well as anti-MV hemagglutinin (HA) or fusion protein (F) mAbs, were found (i) to reverse suppression and (ii) to restore DC allostimulatory capacity. Interestingly, DC-induced T-cell suppression was associated with both phenotypic and functional DC maturation, as demonstrated by IL-12 production and chemotaxis to MIP-3beta. These data suggest that MV infection turns on the maturation program of DC allowing migration to draining lymph nodes, where potent T-cell immune suppression might be achieved via cell surface expression of HA and F glycoproteins, independently of T cell trans-infection.

Dendritic cells recruitment and in vivo priming of CD8+ CTL induced by a single topical or transepithelial immunization via the buccal mucosa with measles virus nucleoprotein

The buccal mucosa, a prototype of pluristratified mucosal epithelia, contains a network of directly accessible class II(+) epithelial dendritic cells (DC), similar to skin Langerhans cells. We showed that a single buccal immunization with measles virus nucleoprotein (NP), by either topical application onto or intradermal injection in the buccal mucosa, induced in vivo priming of protective class I-restricted specific CD8(+) CTL. Both routes of immunization with NP induced a rapid recruitment of DC into the mucosa, which peaked at 2 h and decreased by 24 h. Treatment of mice with Flt3 ligand resulted in an increased number of DC in the buccal mucosa and enhanced the frequency of IFN-gamma-producing NP-specific effectors and the NP-specific CTL response generated after buccal immunization with NP. Finally, NP-pulsed bone marrow-derived DC induced NP-specific IFN-gamma-producing cells upon adoptive transfer to naive mice. These data demonstrate that a viral protein delivered to DC of the buccal mucosa induces in vivo priming of protective anti-viral CD8(+) CTL.