Isoform-specific knockdown of long and intermediate prolactin receptors interferes with evolution of B-cell neoplasms (original) (raw)
Related papers
Prolactin Rescues Immature B-Cells from Apoptosis Induced by B-Cell Receptor Cross-Linking
Journal of Immunology Research, 2016
Prolactin has an immunomodulatory effect and has been associated with B-cell-triggered autoimmune diseases, such as systemic lupus erythematosus (SLE). In mice that develop SLE, the PRL receptor is expressed in early bone marrow B-cells, and increased levels of PRL hasten disease manifestations, which are correlated with a reduction in the absolute number of immature B-cells. The aim of this work was to determine the effect of PRL in anin vitrosystem of B-cell tolerance using WEHI-231 cells and immature B-cells from lupus prone MRL/lpr mice. WEHI-231 cells express the long isoform of the PRL receptor, and PRL rescued the cells from cell death by decreasing the apoptosis induced by the cross-linking of the B-cell antigen receptor (BCR) as measured by Annexin V and active caspase-3. This decrease in apoptosis may have been due to the PRL and receptor interaction, which increased the relative expression of antiapoptotic Bcl-xL and decreased the relative expression of proapoptotic Bad. ...
Molecular Immunology, 2017
Antibodies produced by B-cells provide protection from infectious agents. However, impaired cell death signaling pathways in B-cells can lead to cancer, immunodeficiency or autoimmune diseases. B-cell signaling molecules such as CD20, CD19, Btk, and BAFF-R are targeted by therapeutic drugs and used to treat B-cell derived lymphomas or autoimmune diseases. Nevertheless, B-cells could develop resistance to these therapeutic drugs or the therapeutic drugs may have off-target effects. For instance, repeated rituximab (anti-CD20 antibody) treatment may lead to the loss of its target cell surface molecule, CD20. In addition, in B-cell malignancies, loss of CD19 expression has been observed. Another target molecule, Btk is expressed not only in B-cells but also in mast cells, macrophages, and dendritic cells. Thus, targeting Btk could negatively regulate the functions of innate immunity. The expression of BAFF-R is thought to be restricted to B-cells but it is also expressed on Tcells. Targeting BAFF-R, therefore, may lead to depletion of T-cells in addition to B-cells. B cell receptor (BCR) expression and signaling, however, are critically important for development, differentiation and survival of Bcells. Moreover, BCR is exclusively expressed on B-cells, which makes it an excellent target to avoid off-target effects. B-lymphocytes (B-cells) are core components of adaptive immunity. The main functions of B-cells include antigen presentation and antibody production. However, defects in B-cell growth, development and selection can result in malignancy, immunodeficiency, and autoimmunity (Yanaba et al., 2008; Basso and Dalla-Favera, 2015; Ahn and Cunningham-Rundles, 2009). B cell receptor (BCR) is a transmembrane receptor protein located on the surface of B-cells. Signaling through BCR is required for normal progression of B-cell development. In humans, B-cells are produced in the bone marrow from hematopoietic precursor cells and they migrate to secondary lymphoid organs (periphery) where they encounter antigens. In the bone marrow, the VDJ recombination process produces BCR repertoires that are able to recognize a large array of antigens. In the periphery, B-cells can be activated by a variety of infectious agents through BCR. This phenomenon leads to the formation of germinal centers (GCs) (Pieper et al., 2013). In GCs, B-cells undergo somatic hypermutation (SHM), which increases BCR diversity and thereby increases chances of producing B-cells with high affinity to antigens. However, the SHM process can also lead to the production of autoreactive-B cells (Mackay and Rose, 2001). The BCR complex consists of an antigen-binding subunit and a signaling subunit. The antigen binding subunit is a membrane-bound immunoglobulin (mIg) which lacks any signaling motif. The mIg part consists of two heavy and two light chains combined to each other by disulfide bonds. The signaling subunit consists of the accessory proteins CD79a (Igα) and CD79b (Igβ) which transmit the activating signals to the celĺs interior. The recognition of specific antigens by the mIg, therefore, leads to the activation of a number of kinases such as Brutońs tyrosine kinase (Btk), phosphatidyl-inositol-3-kinase (PI3K) and extracellular signal-regulated kinases (ERKs) (Niiro and Clark, 2002; Treanor, 2012). As we demonstrate in our previous work, the early activation of ERK1 and ERK2 following BCR stimulation results in short-term survival of GC Bcells. However, in the late phase, BCR stimulation leads to inhibition of ERK1 and ERK2, which correlates with cell death (Adem et al., 2015, Fig. 1). Interestingly, BCR-mediated apoptosis of GC B-cells is reversed by CD40 signaling (Adem et al., 2015, Fig. 4). These findings indicate that B-cells which overexpress ERK1 and ERK2 might bypass the selection process. Thus, B-cells which overexpress ERK1/2 and possess memory or plasma cell transcription signatures may transform into self-reactive memory B-cells or auto-antibody producing plasma cells. In addition, it is also possible that B cells which overexpress ERK1/2 but lack differentiation specific signatures may transform into lymphoma cells. Overexpression of Rasgrf-1 amplifies the Ras-ERK pathway in chronic lymphocytic leukemia cells, thereby enhancing B-cell survival. This indicates that malignant B-cells utilize ERKs for their survival (Liao et al., 2014). Moreover, changes in the activation of Ras-ERKs pathway may lead to autoimmune manifestations (Teodorovic et al., 2014). Thus, targeting ERKs may have therapeutic benefits against these B-cell derived diseases. However, because of the critical role of ERKs in various cellular functions, the use of ERK inhibitors can lead to severe cellular toxicity. It is, therefore, imperative to selectively target B-cells in order to avoid the side-effects which could result from off-target inhibition. Rituximab is a chimeric monoclonal antibody which targets CD20, the cell surface differentiation antigen on B-cells. CD20 has a role in B-cell activation and differentiation. It is expressed in mature B-cells but not in hematological stem cells, pro-B cells, normal plasma cells or other tissues. This unique characteristic of CD20 expression makes it the suitable target to treat B-cell derived lymphomas or autoimmune diseases (Du et al., 2007). However, rituximab does not deplete autoreactive antibody-producing plasma cells, because these cells do not express CD20. Nevertheless, rituximab depletes B-cells, thereby decreasing the production of autoreactive antibody and malignant B-cells. The loss of CD20 expression, however, after repeated rituximab treatment may contribute to B-cells' resistance against rituximab (Haidar et al., 2003). A study on CD20 −/− (knockout) mouse has shown normal development and function in CD20 deficient B-cells (Uchida et al., 2004). This data further strengthen the fact that CD20 is not a critical cell surface molecule for the survival and development of B cells. CD19 is another pan B-cell marker used to target and deplete B-cell
Regulation of the B Cell Receptor Repertoire
The TNF-family cytokine BAFF (BLyS) promotes B lymphocyte survival and is overexpressed in individuals with systemic lupus erythematosus and Sjögren's Syndrome. BAFF can rescue anergic autoreactive B cells from death, but only when competition from nonautoreactive B cells is lacking. Yet, high BAFF levels promote autoantibody formation in individuals possessing diverse B cells. To better understand how excess BAFF promotes autoimmunity in a polyclonal immune system, Ig L chain usage was analyzed in 3H9 site-directed IgH chain transgenic mice, whose B cells recognize DNA and chromatin when they express certain endogenous L chains. BAFF levels were manipulated in 3H9 mice by introducing transgenes expressing either BAFF or its natural inhibitor DBAFF. B cells in BAFF/3H9 mice were elevated in number, used a broad L chain repertoire, including L chains generating high-affinity autoreactivity, and produced abundant autoantibodies. Comparison of spleen and lymph node B cells suggested that highly autoreactive B cells were expanded. By contrast, DBAFF/3H9 mice had reduced B cell numbers with a repertoire similar to that of 3H9 mice, but lacking usage of a subset of Vk genes. The results show that limiting BAFF signaling only slightly selects against higher affinity autoreactive B cells, whereas its overexpression leads to broad tolerance escape and positive selection of autoreactive cells. The results have positive implications for the clinical use of BAFF-depleting therapy.
Blood, 2007
Gene expression in cells is a dynamic process but is usually examined at a single time point. We used gene expression profiling over time to build temporal models of gene transcription after B-cell receptor (BCR) signaling in healthy and malignant B cells and chose this as a model since BCR cross-linking induces both cell proliferation and apoptosis, with increased apoptosis in chronic lymphocytic leukemia (CLL) compared to healthy B cells. To determine the basis for this, we examined the global temporal gene expression profile for BCR stimulation and developed a linear combination method to summarize the effect of BCR simulation over all the time points for all patients. Functional learning identified common early events in healthy B cells and CLL cells. Although healthy and malignant B cells share a common genetic pattern early after BCR signaling, a specific genetic program is engaged by the malignant cells at later time points after BCR stimulation. These findings identify the m...
The Journal of Experimental Medicine, 1999
A hallmark of systemic lupus erythematosus and the MRL murine model for lupus is the presence of anti–double-stranded (ds)DNA antibodies (Abs). To identify the steps leading to the production of these Abs in autoimmune mice, we have compared the phenotype and localization of anti-dsDNA B cells in autoimmune (MRL+/+ and lpr/lpr) mice with that in nonautoimmune (BALB/c) mice. Anti-dsDNA B cells are actively regulated in BALB/c mice as indicated by their developmental arrest and accumulation at the T–B interface of the splenic follicle. In the MRL genetic background, anti-dsDNA B cells are no longer developmentally arrested, suggesting an intrinsic B cell defect conferred by MRL background genes. With intact Fas, they continue to exhibit follicular exclusion; however, in the presence of the lpr/lpr mutation, anti-dsDNA B cells are now present in the follicle. Coincident with the altered localization of anti-dsDNA B cells is a follicular infiltration of CD4 T cells. Together, these data...
Clinical and Developmental Immunology, 2013
Prolactin (PRL) plays an important role in modulating the immune response. In B cells, PRL enhances antibody production, including antibodies with self-specificity. In this study, our aims were to determine the level of PRL receptor expression during bone-marrow B-cell development and to assess whether the presence of high PRL serum concentrations influences absolute numbers of developing populations and disease outcome in lupus-prone murine models. We observed that the PRL-receptor is expressed in early bone-marrow B-cell; the expression in lupus-prone mice, which had the highest level of expression in pro-B cells and immature cells, differed from that in wild-type mice. These expression levels did not significantly change in response to hyperprolactinemia; however, populations of pro-B and immature cells from lupus-prone strains showed a decrease in the absolute numbers of cells with high PRL-receptor expression in response to PRL. Because immature self-reactive B cells are consta...
Prolactin modulates the naive B cell repertoire
Journal of Clinical Investigation, 2003
Prolactin is a peptide hormone produced by the anterior pituitary gland that is critical in lactation. Prolactin can also be produced by lymphocytes, and both B and T cells express prolactin receptors. These findings have suggested that prolactin has immunomodulatory functions. Studies in spontaneously autoimmune hosts have demonstrated a role for prolactin in augmenting autoreactivity. We chose to analyze prolactin effects on anti-DNA B cells in nonspontaneously autoimmune female BALB/c mice transgenic for the heavy chain of an anti-DNA antibody. Treatment with prolactin for 4 weeks induced a lupus-like phenotype with an increased number of transgene-expressing B cells, elevated serum anti-DNA antibody titers, and glomerular immunoglobulin deposits. Prolactin caused a decrease in the population of transitional B cells and an increase in mature follicular and marginal zone B cells. The DNA-reactive B cells had a follicular cell phenotype. Anti-DNA hybridomas demonstrated that prolactin alters selection of the naive B cell repertoire. The expansion and activation of anti-DNA B cells in prolactin-treated R4A-γ2b BALB/c mice was dependent on the presence of CD4 + T cells. Finally, treatment with prolactin was unable to break tolerance in R4A-γ2b transgenic C57Bl/6 mice, suggesting that responsiveness of the immune system to prolactin is genetically determined.
Prolactin alters the mechanisms of B cell tolerance induction
Arthritis and Rheumatism, 2009
ObjectiveAutoimmune diseases predominantly affect women, suggesting that female sex hormones may play a role in the pathogenesis of such diseases. We have previously shown that persistent mild-to-moderate elevations in serum prolactin levels induce a break in self tolerance in mice with a BALB/c genetic background. The aim of this study was to evaluate the effects of hyperprolactinemia on the mechanisms of B cell tolerance induction.Autoimmune diseases predominantly affect women, suggesting that female sex hormones may play a role in the pathogenesis of such diseases. We have previously shown that persistent mild-to-moderate elevations in serum prolactin levels induce a break in self tolerance in mice with a BALB/c genetic background. The aim of this study was to evaluate the effects of hyperprolactinemia on the mechanisms of B cell tolerance induction.MethodsEffects of prolactin on splenic B cell subsets were studied in female BALB/c mice. B cell receptor (BCR)–mediated apoptosis and proliferation of transitional B cells were analyzed by flow cytometry. Expression of apoptotic genes was examined by microarrays and real-time polymerase chain reaction analysis. B cells coexpressing κ/λ light chains were assessed by flow cytometry and immunohistochemistry. Activation status of transitional type 3 (T3) B cells was evaluated by BCR-induced calcium influx studies.Effects of prolactin on splenic B cell subsets were studied in female BALB/c mice. B cell receptor (BCR)–mediated apoptosis and proliferation of transitional B cells were analyzed by flow cytometry. Expression of apoptotic genes was examined by microarrays and real-time polymerase chain reaction analysis. B cells coexpressing κ/λ light chains were assessed by flow cytometry and immunohistochemistry. Activation status of transitional type 3 (T3) B cells was evaluated by BCR-induced calcium influx studies.ResultsBCR-mediated apoptosis of the T1 B cell subset, a major checkpoint for negative selection of autoreactive specificities, was decreased in prolactin-treated mice. Microarray studies indicated that this event may be mediated by the prolactin-induced up-regulation of the antiapoptotic gene interferon-γ receptor type II and down-regulation of the proapoptotic gene Trp63. Prolactin treatment also altered the amount of receptor editing, as indicated by the increased number of transitional B cells coexpressing κ/λ light chains. Additionally, hyperprolactinemia modified the level of B cell anergy by increasing the degree of BCR-induced calcium influx in the T3 B cells.BCR-mediated apoptosis of the T1 B cell subset, a major checkpoint for negative selection of autoreactive specificities, was decreased in prolactin-treated mice. Microarray studies indicated that this event may be mediated by the prolactin-induced up-regulation of the antiapoptotic gene interferon-γ receptor type II and down-regulation of the proapoptotic gene Trp63. Prolactin treatment also altered the amount of receptor editing, as indicated by the increased number of transitional B cells coexpressing κ/λ light chains. Additionally, hyperprolactinemia modified the level of B cell anergy by increasing the degree of BCR-induced calcium influx in the T3 B cells.ConclusionPersistently elevated serum prolactin levels interfere with B cell tolerance induction by impairing BCR-mediated clonal deletion, deregulating receptor editing, and decreasing the threshold for activation of anergic B cells, thereby promoting autoreactivity.Persistently elevated serum prolactin levels interfere with B cell tolerance induction by impairing BCR-mediated clonal deletion, deregulating receptor editing, and decreasing the threshold for activation of anergic B cells, thereby promoting autoreactivity.