Background CD22 is a trans-membrane protein exclusively expressed on B cells which regulates adhe... more Background CD22 is a trans-membrane protein exclusively expressed on B cells which regulates adhesion/migration and inhibits cellular responses to B-cell receptor (BCR) stimulation[1]. Spleen tyrosine kinase (Syk) and subsequent phospholipase C (PLC)-γ2-triggered Ca2+ fluxes are rapidly activated after BCR stimulation. CD22 binds specifically to α-2,6-sialic acid residues present on a broad number of proteins, including CD22 itself. Sialo-interactions appear to be crucial for optimal function of CD22 and can occur in cis (to ligands on the same cell surface) or trans (to ligands on neighboring cells). Objectives The humanized anti-CD22 monoclonal antibody epratuzumab, currently being tested in clinical trials, modulates adhesion molecule expression and B cell migration in vitro[2] however, the potential of CD22-ligation with cis and trans sialic acid to regulate BCR signaling has not been delineated. Methods In vitro effects of epratuzumab on BCR-induced signaling were evaluated by analyzing the phosphorylation of BCR-signaling molecules (Syk/PLC-γ2) and Ca2+ flux. The influence of epratuzumab on the phosphorylation of the BCR signaling molecules Syk and PLC-γ2 was studied in vitro by flow cytometry in PBMCs from healthy donors. To investigate the effect of sialo-interaction on the effects by epratuzumab, PBMCs were treated with neuraminidase (to remove sialic acic) and BCR induced phosphorylation (Syk and PLC-γ2) was detected with or without epratuzumab incubation. To monitor the concentration of intracellular Ca2+, B cells pre-loaded with Indo-1AM were incubated with or without F(ab’)2-epratuzumab for 60 minutes at 37°C and were subsequently stimulated with F(ab’)2 anti-IgM/IgG. Intracellular Ca2+ concentrations were monitored by flow cytometry over 10 minutes after activation. Results Epratuzumab inhibited Syk and PLC-γ2 phosphorylation after in vitro BCR stimulation by 23±9% and 33±5, respectively. Interestingly, preventing sialo-interactions of CD22 partially reduced the inhibitory effect of epratuzumab on Syk and PLC-γ2 phosphorylation to 12±6% and 22±4%, respectively. The inhibition of kinase phosphorylation was demonstrated in both CD27- and CD27+ memory B cells and appeared to be independent of FcR signaling since a F(ab’)2 fragment of epratuzumab induced comparable results to the full antibody. In addition, a F(ab’)2 fragment of epratuzumab reduced the BCR-induced calcium flux. These data are consistent with the potential of targeting CD22 to raise the threshold of BCR activation which also provides additional control of B cell function. Conclusions Intracellular BCR signals can be partially inhibited by CD22 ligation with epratuzumab, providing further understanding of targeting CD22 biology in human autoimmune diseases. This study was supported by Sonderforschungsbereich 650 and DFG491/7-1 and in part by UCB Pharma Inc. References Nitschke L. The role of CD22 and other inhibitory co-receptors in B-cell activation. Current opinion in immunology 2005;17:290–7. Daridon C, Blassfeld D, Reiter K, et al. Epratuzumab targeting of CD22 affects adhesion molecule expression and migration of B-cells in systemic lupus erythematosus. Arthritis Research & Therapy 2010;12:R204. Disclosure of Interest N. Sieger: None Declared, S. Fleischer: None Declared, H. Mei: None Declared, K. Reiter: None Declared, A. Shock Employee of: UCB Pharma inc., G. Burmester: None Declared, C. Daridon: None Declared, T. Dörner Grant/Research support from: Immunomedics
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-... more Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-tolerance, autoantibody production, B cell hyperreactivity and an impaired B cell homeostasis. Recent data suggested that an impaired B cell response could also lead to autoimmunity. In this study, the BCR downstream signaling spleen tyrosine kinase Syk of healthy donors (HD), SLE, rheumatoid arthritis (RA) and primary Sjögren’s syndrome (pSS) patients was analyzed in detail and revealed new insights into peripheral B cell abnormalities based on intracellular characteristics. Interestingly, SLE B cells showed a significantly lower but long-lasting Syk (Y352) phosphorylation after BCR engagement compared to HD (p<0.05). Furthermore, a significant enlarged frequency of Syk(bright) B cell population has been identified within the CD27(-) B cell subset in the blood of SLE patients (p<0.001), but no correlation with the disease activity was observed. Notably, the frequency of Syk(bright) B cells was not increased in RA or pSS patients. Further characterization showed that Syk(bright) cells exhibit an increased basal level of phosphorylated Syk, expressed higher levels of CD19 and CD95 and mainly do not express CD38 as compared to Syk(dim) cells. Thus, SLE patients show a diminished but long-lasting BCR response and exhibit an enlarged unique Syk(bright) B cell subset that could be responsible for the hyperactivity of SLE B cells.
During mucosal immune responses, IgA-secreting plasmablasts are generated from mucosal B cells. W... more During mucosal immune responses, IgA-secreting plasmablasts are generated from mucosal B cells. We previously demonstrated that at steady-state, most human peripheral blood antibody-secreting cells produce IgA and express mucosal homing receptors, and suggested their generation in mucosal immune responses. In the current study, we analyzed the blood of patients who received B cell depletion therapy with rituximab (anti-CD20) for treatment of rheumatoid arthritis before and at 2-9months after rituximab infusion by flow cytometry. While CD20+ B cells were reduced to <0.02% of their intial numbers before therapy, CD19+/CD27hi/CD20- antibody-secreting cells remained detectable in the blood at 26-119% of their initial numbers. These circulating antibody-secreting cells expressed IgA that bound to bacterial antigens, beta7 integrin and CCR10 before and during B cell depletion, suggesting their mucosal origin. High expression of HLA-DR and Ki-67 and in vitro migration towards CCL28 and CXCL12 qualified these cells as recently activated plasmablasts, reflecting the survival of functional B cells during rituximab treatment. Consistently, IgA+ plasmablasts and plasma cells were identified in the lamina propria during B cell depletion. Our data implicate that a population of mucosal B cells is resistant to rituximab and self-sufficient in adult humans and not replenished by CD20+ B cells immigrating from blood, lymphoid tissue, or bone marrow, that is, B cells depleted by rituximab.
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-... more Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-tolerance, autoantibody production, B cell hyperreactivity and an impaired B cell homeostasis. Recent data suggested that an impaired B cell response could also lead to autoimmunity. In this study, the BCR downstream signaling spleen tyrosine kinase Syk of healthy donors (HD), SLE, rheumatoid arthritis (RA) and primary Sjögren’s syndrome (pSS) patients was analyzed in detail and revealed new insights into peripheral B cell abnormalities based on intracellular characteristics. Interestingly, SLE B cells showed a significantly lower but long-lasting Syk (Y352) phosphorylation after BCR engagement compared to HD (p<0.05). Furthermore, a significant enlarged frequency of Syk(bright) B cell population has been identified within the CD27(-) B cell subset in the blood of SLE patients (p<0.001), but no correlation with the disease activity was observed. Notably, the frequency of Syk(brigh...
ObjectiveTo identify the cells that produce BAFF in the salivary glands of patients with primary ... more ObjectiveTo identify the cells that produce BAFF in the salivary glands of patients with primary Sjögren's syndrome (SS), and to analyze BAFF receptor expression by local T and B lymphocytes.MethodsWe used 3 methods to identify the source of BAFF: in situ hybridization of the transcripts for BAFF combined with staining of membrane markers, regular and real‐time reverse transcription–polymerase chain reaction (RT‐PCR) of cultured epithelial cells, and RT‐PCR of sorted single‐cell T and B lymphocytes eluted from salivary glands. Cells expressing TACI, BCMA, and B lymphocyte stimulator receptor 3 (BR‐3) were disclosed by combining each specific staining of the receptors with each specific staining of the cells. The function of BAFF generated by epithelial cells on B lymphocytes was determined in short‐term cocultures.ResultsTranscripts for BAFF were seen in epithelial cells and infiltrating T lymphocytes and, for the first time, were detected in local B cells. It is interesting tha...
Background CD22, a transmembrane protein exclusively expressed on B cells, mediates migration by ... more Background CD22, a transmembrane protein exclusively expressed on B cells, mediates migration by cell–cell interaction and negatively regulates B-cell receptor (BCR) signaling. CD22 acts as an inhibitory co-receptor of the BCR via de-phosphorylation of signaling molecules such as spleen tyrosine kinase (Syk) and subsequent phospholipase C (PLC)-γ2-triggered Ca2+ fluxes. The humanized anti-CD22 monoclonal antibody epratuzumab modulates adhesion molecule expression and B-cell migration in vitro. However, the potential of CD22 to regulate BCR signaling has not been fully delineated. Objectives As toll-like receptor (TLR)-dependent activation of B cells represents an important pathway of B-cell hyperactivity in autoimmunity, our studies addressed whether epratuzumab might be able to modulate BCR signaling pathways in TLR9 pre-activated B cells or whether TLR9 activation abrogates the inhibitory effect of epratuzumab on the BCR signaling. Methods Our study focused on the influence of epratuzumab on the B cells’ response to BCR alone or in combination with TLR9. The recruitment of CD22 to the BCR (CD79α) after epratuzumab incubation on B cells from healthy volunteers was analyzed by confocal microscopy. The in vitro effects of epratuzumab on BCR-induced signaling were evaluated by analyzing the phosphorylation status of BCR-signaling molecules, Syk and PLC-γ2 by flow cytometry with or without TLR9 pre-activation. The concentration of intracellular Ca2+ was monitored by flow cytometry after BCR stimulation. Finally, to evaluate the origin of the Ca2+ flux, extracellular Ca2+ was chelated with 1 mM ethylene glycol tetraacetic acid (EGTA). Results B cells incubated with epratuzumab showed a specific co-localization of CD22 to the BCR-associated molecule CD79α on B cells. In addition, pre-treatment with epratuzumab led to a reduction in the MFI of phosphorylated Syk and PLC-γ2 induced by BCR stimulation compared with IgG1 isotype control. Similar results were observed when the cells were pre-incubated with F(ab’)2 fragment of epratuzumab, which excludes an inhibitory effect dependent on FcR signaling. Interestingly, the reduction of BCR induced kinase phosphorylation was demonstrated in both CD27- and CD27+ memory B cells. In addition, pre-activation of B cells by TLR9 did not circumvent the influence of epratuzumab on BCR signaling, as shown by a reduction in the MFI of phosphorylated Syk and PLC-γ2 in comparison to non-activated cells. Finally, a F(ab’)2 fragment of epratuzumab reduced BCR-induced calcium mobilization. Conclusions Intracellular BCR signals can be modulated by CD22 ligation using epratuzumab, and pre-activation with TLR9 did not circumvent this effect. These data expand the potential mechanisms of action of epratuzumab. Disclosure of Interest N. Sieger Grant/research support from: UCB Pharma, S. Fleischer Grant/research support from: UCB Pharma, K. Reiter Grant/research support from: UCB Pharma, H. Mei Grant/research support from: UCB Pharma, A. Shock Employee of: UCB Pharma, G. Burmester Grant/research support from: UCB Pharma, C. Daridon Grant/research support from: UCB Pharma, T. Dörner Grant/research support from: UCB Pharma, Consultant for: UCB Pharma
Background:Glucocorticoid (GC) therapy has strong anti-inflammatory effects and helps slow radiog... more Background:Glucocorticoid (GC) therapy has strong anti-inflammatory effects and helps slow radiographic progression in RA1; however, GCs can be associated with adverse events (AEs) such as infection, especially with long-term use and higher doses.Objectives:To evaluate the impact of baseline GCs on the efficacy and safety of upadacitinib (UPA) with or without concomitant conventional synthetic DMARDs (csDMARDs).Methods:In this ad hoc analysis of three Phase 3 studies, patients with inadequate response to MTX (MTX-IR) receiving UPA 15 mg once daily (QD) or placebo (PBO) + csDMARDs in SELECT-NEXT, and MTX-IR/MTX-naïve patients receiving UPA 15 mg QD monotherapy or MTX monotherapy in SELECT-MONOTHERAPY/SELECT-EARLY, respectively, were included. Efficacy outcomes, including measures of remission and low disease activity (LDA) determined by DAS in 28 joints using CRP (DAS28[CRP]; <2.6/≤3.2) and Clinical Disease Activity Index (CDAI; ≤2.8/≤10), were assessed and stratified by baseline ...
The binding of antigen to the B cell receptor (BCR) results in a cascade of signalling events tha... more The binding of antigen to the B cell receptor (BCR) results in a cascade of signalling events that ultimately drive B cell activation. Uncontrolled B cell activation is regulated by negative feedback loops that involve inhibitory co-receptors such as CD22 and CD32B that exert their functions following phosphorylation of immunoreceptor tyrosine-based inhibition motifs (ITIMs). The CD22-targeted antibody epratuzumab has previously been shown to inhibit BCR-driven signalling events, but its effects on ITIM phosphorylation of CD22 and CD32B have not been properly evaluated. The present study therefore employed both immunoprecipitation and flow cytometry approaches to elucidate the effects of epratuzumab on direct phosphorylation of key tyrosine (Tyr) residues on both these proteins, using both transformed B cell lines and primary human B cells. Epratuzumab induced the phosphorylation of Tyr(822) on CD22 and enhanced its co-localisation with SHP-1. Additionally, in spite of high basal ph...
Background CD22 is a trans-membrane protein exclusively expressed on B cells which regulates adhe... more Background CD22 is a trans-membrane protein exclusively expressed on B cells which regulates adhesion/migration and inhibits cellular responses to B-cell receptor (BCR) stimulation[1]. Spleen tyrosine kinase (Syk) and subsequent phospholipase C (PLC)-γ2-triggered Ca2+ fluxes are rapidly activated after BCR stimulation. CD22 binds specifically to α-2,6-sialic acid residues present on a broad number of proteins, including CD22 itself. Sialo-interactions appear to be crucial for optimal function of CD22 and can occur in cis (to ligands on the same cell surface) or trans (to ligands on neighboring cells). Objectives The humanized anti-CD22 monoclonal antibody epratuzumab, currently being tested in clinical trials, modulates adhesion molecule expression and B cell migration in vitro[2] however, the potential of CD22-ligation with cis and trans sialic acid to regulate BCR signaling has not been delineated. Methods In vitro effects of epratuzumab on BCR-induced signaling were evaluated by analyzing the phosphorylation of BCR-signaling molecules (Syk/PLC-γ2) and Ca2+ flux. The influence of epratuzumab on the phosphorylation of the BCR signaling molecules Syk and PLC-γ2 was studied in vitro by flow cytometry in PBMCs from healthy donors. To investigate the effect of sialo-interaction on the effects by epratuzumab, PBMCs were treated with neuraminidase (to remove sialic acic) and BCR induced phosphorylation (Syk and PLC-γ2) was detected with or without epratuzumab incubation. To monitor the concentration of intracellular Ca2+, B cells pre-loaded with Indo-1AM were incubated with or without F(ab’)2-epratuzumab for 60 minutes at 37°C and were subsequently stimulated with F(ab’)2 anti-IgM/IgG. Intracellular Ca2+ concentrations were monitored by flow cytometry over 10 minutes after activation. Results Epratuzumab inhibited Syk and PLC-γ2 phosphorylation after in vitro BCR stimulation by 23±9% and 33±5, respectively. Interestingly, preventing sialo-interactions of CD22 partially reduced the inhibitory effect of epratuzumab on Syk and PLC-γ2 phosphorylation to 12±6% and 22±4%, respectively. The inhibition of kinase phosphorylation was demonstrated in both CD27- and CD27+ memory B cells and appeared to be independent of FcR signaling since a F(ab’)2 fragment of epratuzumab induced comparable results to the full antibody. In addition, a F(ab’)2 fragment of epratuzumab reduced the BCR-induced calcium flux. These data are consistent with the potential of targeting CD22 to raise the threshold of BCR activation which also provides additional control of B cell function. Conclusions Intracellular BCR signals can be partially inhibited by CD22 ligation with epratuzumab, providing further understanding of targeting CD22 biology in human autoimmune diseases. This study was supported by Sonderforschungsbereich 650 and DFG491/7-1 and in part by UCB Pharma Inc. References Nitschke L. The role of CD22 and other inhibitory co-receptors in B-cell activation. Current opinion in immunology 2005;17:290–7. Daridon C, Blassfeld D, Reiter K, et al. Epratuzumab targeting of CD22 affects adhesion molecule expression and migration of B-cells in systemic lupus erythematosus. Arthritis Research & Therapy 2010;12:R204. Disclosure of Interest N. Sieger: None Declared, S. Fleischer: None Declared, H. Mei: None Declared, K. Reiter: None Declared, A. Shock Employee of: UCB Pharma inc., G. Burmester: None Declared, C. Daridon: None Declared, T. Dörner Grant/Research support from: Immunomedics
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-... more Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-tolerance, autoantibody production, B cell hyperreactivity and an impaired B cell homeostasis. Recent data suggested that an impaired B cell response could also lead to autoimmunity. In this study, the BCR downstream signaling spleen tyrosine kinase Syk of healthy donors (HD), SLE, rheumatoid arthritis (RA) and primary Sjögren’s syndrome (pSS) patients was analyzed in detail and revealed new insights into peripheral B cell abnormalities based on intracellular characteristics. Interestingly, SLE B cells showed a significantly lower but long-lasting Syk (Y352) phosphorylation after BCR engagement compared to HD (p&lt;0.05). Furthermore, a significant enlarged frequency of Syk(bright) B cell population has been identified within the CD27(-) B cell subset in the blood of SLE patients (p&lt;0.001), but no correlation with the disease activity was observed. Notably, the frequency of Syk(bright) B cells was not increased in RA or pSS patients. Further characterization showed that Syk(bright) cells exhibit an increased basal level of phosphorylated Syk, expressed higher levels of CD19 and CD95 and mainly do not express CD38 as compared to Syk(dim) cells. Thus, SLE patients show a diminished but long-lasting BCR response and exhibit an enlarged unique Syk(bright) B cell subset that could be responsible for the hyperactivity of SLE B cells.
During mucosal immune responses, IgA-secreting plasmablasts are generated from mucosal B cells. W... more During mucosal immune responses, IgA-secreting plasmablasts are generated from mucosal B cells. We previously demonstrated that at steady-state, most human peripheral blood antibody-secreting cells produce IgA and express mucosal homing receptors, and suggested their generation in mucosal immune responses. In the current study, we analyzed the blood of patients who received B cell depletion therapy with rituximab (anti-CD20) for treatment of rheumatoid arthritis before and at 2-9months after rituximab infusion by flow cytometry. While CD20+ B cells were reduced to &lt;0.02% of their intial numbers before therapy, CD19+/CD27hi/CD20- antibody-secreting cells remained detectable in the blood at 26-119% of their initial numbers. These circulating antibody-secreting cells expressed IgA that bound to bacterial antigens, beta7 integrin and CCR10 before and during B cell depletion, suggesting their mucosal origin. High expression of HLA-DR and Ki-67 and in vitro migration towards CCL28 and CXCL12 qualified these cells as recently activated plasmablasts, reflecting the survival of functional B cells during rituximab treatment. Consistently, IgA+ plasmablasts and plasma cells were identified in the lamina propria during B cell depletion. Our data implicate that a population of mucosal B cells is resistant to rituximab and self-sufficient in adult humans and not replenished by CD20+ B cells immigrating from blood, lymphoid tissue, or bone marrow, that is, B cells depleted by rituximab.
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-... more Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a breakdown of self-tolerance, autoantibody production, B cell hyperreactivity and an impaired B cell homeostasis. Recent data suggested that an impaired B cell response could also lead to autoimmunity. In this study, the BCR downstream signaling spleen tyrosine kinase Syk of healthy donors (HD), SLE, rheumatoid arthritis (RA) and primary Sjögren’s syndrome (pSS) patients was analyzed in detail and revealed new insights into peripheral B cell abnormalities based on intracellular characteristics. Interestingly, SLE B cells showed a significantly lower but long-lasting Syk (Y352) phosphorylation after BCR engagement compared to HD (p<0.05). Furthermore, a significant enlarged frequency of Syk(bright) B cell population has been identified within the CD27(-) B cell subset in the blood of SLE patients (p<0.001), but no correlation with the disease activity was observed. Notably, the frequency of Syk(brigh...
ObjectiveTo identify the cells that produce BAFF in the salivary glands of patients with primary ... more ObjectiveTo identify the cells that produce BAFF in the salivary glands of patients with primary Sjögren's syndrome (SS), and to analyze BAFF receptor expression by local T and B lymphocytes.MethodsWe used 3 methods to identify the source of BAFF: in situ hybridization of the transcripts for BAFF combined with staining of membrane markers, regular and real‐time reverse transcription–polymerase chain reaction (RT‐PCR) of cultured epithelial cells, and RT‐PCR of sorted single‐cell T and B lymphocytes eluted from salivary glands. Cells expressing TACI, BCMA, and B lymphocyte stimulator receptor 3 (BR‐3) were disclosed by combining each specific staining of the receptors with each specific staining of the cells. The function of BAFF generated by epithelial cells on B lymphocytes was determined in short‐term cocultures.ResultsTranscripts for BAFF were seen in epithelial cells and infiltrating T lymphocytes and, for the first time, were detected in local B cells. It is interesting tha...
Background CD22, a transmembrane protein exclusively expressed on B cells, mediates migration by ... more Background CD22, a transmembrane protein exclusively expressed on B cells, mediates migration by cell–cell interaction and negatively regulates B-cell receptor (BCR) signaling. CD22 acts as an inhibitory co-receptor of the BCR via de-phosphorylation of signaling molecules such as spleen tyrosine kinase (Syk) and subsequent phospholipase C (PLC)-γ2-triggered Ca2+ fluxes. The humanized anti-CD22 monoclonal antibody epratuzumab modulates adhesion molecule expression and B-cell migration in vitro. However, the potential of CD22 to regulate BCR signaling has not been fully delineated. Objectives As toll-like receptor (TLR)-dependent activation of B cells represents an important pathway of B-cell hyperactivity in autoimmunity, our studies addressed whether epratuzumab might be able to modulate BCR signaling pathways in TLR9 pre-activated B cells or whether TLR9 activation abrogates the inhibitory effect of epratuzumab on the BCR signaling. Methods Our study focused on the influence of epratuzumab on the B cells’ response to BCR alone or in combination with TLR9. The recruitment of CD22 to the BCR (CD79α) after epratuzumab incubation on B cells from healthy volunteers was analyzed by confocal microscopy. The in vitro effects of epratuzumab on BCR-induced signaling were evaluated by analyzing the phosphorylation status of BCR-signaling molecules, Syk and PLC-γ2 by flow cytometry with or without TLR9 pre-activation. The concentration of intracellular Ca2+ was monitored by flow cytometry after BCR stimulation. Finally, to evaluate the origin of the Ca2+ flux, extracellular Ca2+ was chelated with 1 mM ethylene glycol tetraacetic acid (EGTA). Results B cells incubated with epratuzumab showed a specific co-localization of CD22 to the BCR-associated molecule CD79α on B cells. In addition, pre-treatment with epratuzumab led to a reduction in the MFI of phosphorylated Syk and PLC-γ2 induced by BCR stimulation compared with IgG1 isotype control. Similar results were observed when the cells were pre-incubated with F(ab’)2 fragment of epratuzumab, which excludes an inhibitory effect dependent on FcR signaling. Interestingly, the reduction of BCR induced kinase phosphorylation was demonstrated in both CD27- and CD27+ memory B cells. In addition, pre-activation of B cells by TLR9 did not circumvent the influence of epratuzumab on BCR signaling, as shown by a reduction in the MFI of phosphorylated Syk and PLC-γ2 in comparison to non-activated cells. Finally, a F(ab’)2 fragment of epratuzumab reduced BCR-induced calcium mobilization. Conclusions Intracellular BCR signals can be modulated by CD22 ligation using epratuzumab, and pre-activation with TLR9 did not circumvent this effect. These data expand the potential mechanisms of action of epratuzumab. Disclosure of Interest N. Sieger Grant/research support from: UCB Pharma, S. Fleischer Grant/research support from: UCB Pharma, K. Reiter Grant/research support from: UCB Pharma, H. Mei Grant/research support from: UCB Pharma, A. Shock Employee of: UCB Pharma, G. Burmester Grant/research support from: UCB Pharma, C. Daridon Grant/research support from: UCB Pharma, T. Dörner Grant/research support from: UCB Pharma, Consultant for: UCB Pharma
Background:Glucocorticoid (GC) therapy has strong anti-inflammatory effects and helps slow radiog... more Background:Glucocorticoid (GC) therapy has strong anti-inflammatory effects and helps slow radiographic progression in RA1; however, GCs can be associated with adverse events (AEs) such as infection, especially with long-term use and higher doses.Objectives:To evaluate the impact of baseline GCs on the efficacy and safety of upadacitinib (UPA) with or without concomitant conventional synthetic DMARDs (csDMARDs).Methods:In this ad hoc analysis of three Phase 3 studies, patients with inadequate response to MTX (MTX-IR) receiving UPA 15 mg once daily (QD) or placebo (PBO) + csDMARDs in SELECT-NEXT, and MTX-IR/MTX-naïve patients receiving UPA 15 mg QD monotherapy or MTX monotherapy in SELECT-MONOTHERAPY/SELECT-EARLY, respectively, were included. Efficacy outcomes, including measures of remission and low disease activity (LDA) determined by DAS in 28 joints using CRP (DAS28[CRP]; <2.6/≤3.2) and Clinical Disease Activity Index (CDAI; ≤2.8/≤10), were assessed and stratified by baseline ...
The binding of antigen to the B cell receptor (BCR) results in a cascade of signalling events tha... more The binding of antigen to the B cell receptor (BCR) results in a cascade of signalling events that ultimately drive B cell activation. Uncontrolled B cell activation is regulated by negative feedback loops that involve inhibitory co-receptors such as CD22 and CD32B that exert their functions following phosphorylation of immunoreceptor tyrosine-based inhibition motifs (ITIMs). The CD22-targeted antibody epratuzumab has previously been shown to inhibit BCR-driven signalling events, but its effects on ITIM phosphorylation of CD22 and CD32B have not been properly evaluated. The present study therefore employed both immunoprecipitation and flow cytometry approaches to elucidate the effects of epratuzumab on direct phosphorylation of key tyrosine (Tyr) residues on both these proteins, using both transformed B cell lines and primary human B cells. Epratuzumab induced the phosphorylation of Tyr(822) on CD22 and enhanced its co-localisation with SHP-1. Additionally, in spite of high basal ph...
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