Structure and function of B-cell linker and its role in the development of B cell-related diseases / 南方医科大学学报

B cell linker (BLNK) is a key linker protein of B cell receptor (BCR) signaling pathway. BLNK participates in the regulation of PLC-γactivity and the activation of Ras pathway through its typical structure and interaction network with other proteins, and is thus widely involved in the regulation of B cell proliferation, differentiation, apoptosis and signal transduction. Furthermore, it is closely related to anaphylactic diseases, multiple sclerosis, chromosomal aneuploidy, aneuglobulinemia, B lymphocytic leukemia and lymphoma. Herein we review the structure and biological function of BLNK and its role in B cell-related diseases. BLNK can cooperate with a series of effective proteins to activate BCR signaling pathway, thereby regulating the development, maturation and function of B cells. The functional mutation of BLNK can destroy the homeostasis of B cells and affect the development and maturation of B cells, which leads to the occurrence of B cell related diseases. A comprehensive understanding of the biological functions of BLNK not only provides insights into the pathogenesis of B cell-related diseases, but also inspires new ideas and helps to find breakthroughs for the treatment of these diseases with BLNK as the therapeutic target.

Progress of microRNAs and B-cell receptor signaling pathway in chronic lymphocytic leukemia / 白血病·淋巴瘤

Many studies have confirmed that dysregulation of microRNAs (miRNAs) expression can cause disruption of the hematopoietic system and contribute to leukemogenesis by regulating the expression of some oncogenes and anti-oncogenes. Chronic lymphocytic leukemia (CLL) is a malignant proliferative disease of B lymphocytes with significant heterogeneity in the incidence of individuals, disease progression, treatment response and clinical prognosis. The increasing studies have shown that the mutation or abnormal expression of miRNAs is closely related to CLL occurrence, progression, prognosis and curative efficacy. Certain miRNAs are involved in the intricate interplay with B-cell receptor (BCR) signaling pathway. The review discusses the latest progress of miRNAs expression in BCR signaling pathway and CLL onset and progression.

Characteristics of IgH-CDR3 repertoire of peripheral B cells in a patient with primary biliary cholangitis: a preliminary study using high-throughput sequencing / 中华肝脏病杂志

Objective@#To analyze the characteristics of immunoglobulin heavy chain complementarity-determining region (IgH-CDR3) repertoire of peripheral B cells in a patient with primary biliary cholangitis (PBC) and to investigate the diversity of the immune system.@*Methods@#Arm-PCR was used to amplify the IgH-CDR3 region of circulating B cells isolated from a PBC patient, and high-throughput sequencing was used to analyze the amplified product. The characteristics of immune repertoire were analyzed by bioinformatics.@*Results@#In total, 329219 sequence reads were generated from the sample, with 325540 total CDR3 sequences and 72774 distinct CDR3 sequences, and the D50 of IGH-CDR3 was 7.7. The dominant CDR3 length of the sample was 45 nt (9.6%); the N addition with the highest frequency ranged from 13 to 14 nt (5.25%); the J trimming with the highest frequency was 0 nt (12.7%); the three most frequent V alleles were V4-59 (9.5%), V3-23 (8.1%), and V1-69 (6.4%).@*Conclusion@#The diversity of IgH-CDR3 repertoire is relatively low in this patient with PBC, with several B-cell clonal expansions. The specificity needs to be further verified after increasing the sample size.

Application and resistance mechanism of B-cell receptor signaling pathway inhibitors in lymphoma:reports from the 57th American Society of Hematology annual meeting / 白血病·淋巴瘤

With the recent success of B-cell receptor (BCR) signaling pathway inhibitor in the treatment of patients with relapsed or refractory non-Hodgkin lymphoma (NHL), a number of new agents targeting the BCR signaling pathway are in a clinical research stage. In addition, multiple trials combining these agents with conventional cytotoxic chemotherapy, immunomodulatory agents, monoclonal antibodies, or other kinase inhibitors are underway. Studies have also found the drug resistance of BCR signaling pathway inhibitors, drawing attention of the mechanism and the way to overcome the drug resistance. Combined with the research progress reported in 57th American Society of Hematology (ASH) annual meeting, this article summarized the recent progress of BCR signaling pathway inhibitors and their resistance mechanism to provide new information on clinical therapy.

Research progress of B cell receptor pathway inhibitors in the treatment of chronic lymphocytic leukemia:reports from the 57th American Society of Hematology annual meeting / 白血病·淋巴瘤

With the recent success of the Bruton's tyrosine kinase (BTK) inhibitor, ibrutinib, and the phosphoinositide-3-kinase (PI3K) inhibitor idelalisib in the treatment of patients with relapsed or refractory chronic lymphocytic leukemia (CLL), a number of new agents targeting the B cell receptor (BCR) pathway are in clinical development. In the 57th American Society of Hematology (ASH) annual meeting, great interests are still focused on these two drugs, either monotherapy or combination in the treatment of CLL. On the other hand, SYK inhibitors, new BTK and PI3K antagonists are also coming to the forefront, casting a new light on the treatment of ibrutinib/idelalisb-resistant patients. The progresses of BCR pathway inhibitors in CLL will be summarized in this paper based on the reports in the 57th ASH annual meeting.

Targeting B-cell receptor signaling: Changing the treatment landscape of B-cell Lymphoma.

Introduced in 1998, the anti-CD20 monoclonal antibody rituximab, with its unique mechanism of action, was the first agent to improve survival in patients with B-cell lymphoma (BCL) treated with chemotherapy. Laboratory investigation of the B-cell receptor signaling pathway identified the critical nature of this pathway for normal B-cell development, survival and proliferation. Further investigation showed that lymphoma cell lines were also dependent upon this pathway and hence small molecule inhibitors of critical proteins in the pathway were synthesized and shown to be cytotoxic. Subsequent translation to the clinic has shown impressive activity in some types of B-cell lymphoma. The aim of this article is to provide an overview of the constituents of the BCR signaling pathway, to illustrate how addiction to this pathway is critical for survival of some BCL, and to summarize the clinical experience with novel small molecule inhibitors of specific proteins in the BCR pathway. We speculate that combination of these agents with newer drugs, each with a unique mechanism of action might lead to improved therapy and the eventual elimination of standard chemotherapy from our therapeutic arsenal.

Study progress of the stereotyped B-cell receptor in chronic lymphocytic leukemia: reports in the 54 ASH annual meeting / 白血病·淋巴瘤

B-cell receptors play an important role in the mechanism of chronic lymphocytic leukemia.Distinct CLL B-cell receptors exhibit particular biological features and behaviors to specific modes of microenvironmental interactions leading to clonal evolution and adverse outcome.

Next generation sequencing: new tools in immunology and hematology

One of the hallmarks of the adaptive immune system is the specificity of B and T cell receptors. Thanks to somatic recombination, a large repertoire of receptors can be generated within an individual that guarantee the recognition of a vast number of antigens. Monoclonal antibodies have limited applicability, given the high degree of diversity among these receptors, in BCR and TCR monitoring. Furthermore, with regard to cancer, better characterization of complex genomes and the ability to monitor tumor-specific cryptic mutations or translocations are needed to develop better tailored therapies. Novel technologies, by enhancing the ability of BCR and TCR monitoring, can help in the search for minimal residual disease during hematological malignancy diagnosis and follow-up, and can aid in improving bone marrow transplantation techniques. Recently, a novel technology known as next generation sequencing has been developed; this allows the recognition of unique sequences and provides depth of coverage, heterogeneity, and accuracy of sequencing. This provides a powerful tool that, along with microarray analysis for gene expression, may become integral in resolving the remaining key problems in hematology. This review describes the state of the art of this novel technology, its application in the immunological and hematological fields, and the possible benefits it will provide for the hematology and immunology community.

CD40 Co-stimulation Inhibits Sustained BCR-induced Ca2+ Signaling in Response to Long-term Antigenic Stimulation of Immature B Cells

Regulation of B cell receptor (BCR)-induced Ca2+ signaling by CD40 co-stimulation was compared in long-term BCR-stimulated immature (WEHI-231) and mature (Bal-17) B cells. In response to long-term pre-stimulation of immature WEHI-231 cells to alpha-IgM antibody (0.5~48 hr), the initial transient decrease in BCR-induced [Ca2+]i was followed by spontaneous recovery to control level within 24 hr. The recovery of Ca2+ signaling in WEHI-231 cells was not due to restoration of internalized receptor but instead to an increase in the levels of PLCgamma2 and IP3R-3. CD40 co-stimulation of WEHI-231 cells prevented BCR-induced cell cycle arrest and apoptosis, and it strongly inhibited the recovery of BCR-induced Ca2+ signaling. CD40 co-stimulation also enhanced BCR internalization and reduced expression of PLCgamma2 and IP3R-3. Pre-treatment of WEHI-231 cells with the antioxidant N-acetyl-L-cysteine (NAC) strongly inhibited CD40-mediated prevention of the recovery of Ca2+ signaling. In contrast to immature WEHI-231 cells, identical long-term alpha-IgM pre-stimulation of mature Bal-17 cells abolished the increase in BCR-induced [Ca2+]i, regardless of CD40 co-stimulation. These results suggest that CD40-mediated signaling prevents antigen-induced cell cycle arrest and apoptosis of immature B cells through inhibition of sustained BCR-induced Ca2+ signaling.

Identification of Eight Novel Alternative Splicing Forms of CD72 and Their Differential Expression in a Mouse Model of SLE / 生物化学与生物物理进展

CD72 is a B cell specific receptor that exists in multiple alternative splicing forms. Eight novel alternative splicing forms of CD72 were identified from the spleenocytes of BALB/C mice. Two very unique intron sequences were found in those alternative splicing forms. One kind of splicing variants retained the intron1 in the mRNA. This intron can be translated into 32 amino acid residues without changing the reading frame of the whole proteins. Another kind of splicing variants used an alternative 3' splice site in intron 3(3'AS) which led to premature termination of its encoded protein. The differential expression of the CD72 splicing variants were compared in BALB/C and NZB/W mice that were at different stage of systematic lupus erythematosis(SLE) disease development. It was found that 1) splicing forms containing 3'AS was rare in all samples examinated; 2) splicing forms containing two ITIM domains and transmembrane domains were more abundant in BALB/C mice than in NZB/W mice, even in some cases the two ITIM domains were separated by the intron 1; 3) a shorter splicing form with both exon2 and exon3 missing was expressed highly in terminally diseased NZB/W mice.These results suggested an important role of CD72 alternative splicing forms in B cell receptor signaling and in SLE.

Application of Gene Rearrangement Analysis for Diagnosis of Malignant Lymphoma

To evaluate the utility of gene rearrangement analysis, eight cases of malignant lymphoma, one case of Hodgkin's disease, two cases of angioiminunoblastic lymphadenopathy (AILD) and two cases of non-specific lymphadenitis were studied by immunohistochemical and genetic analysis. Southern blot analysis was perfon-ned by a using vacuum transfer system and a biotin labelled probe. This method was faster, safer, and more convenient than conventional methods. Gene rearrangement study showed rearranged novel bands in five of six cases of B cell lymphoma, in all cases of T cell lymphoma, and in all cases of AILD. No rearrangement of the B cell receptor(BCR) or of the T cell receptor(TCR) was seen in Hodgkin's disease or in nonspecific lymphadenitis. These results suggest that gene rearrangement analysis of BCR and TCR is a recommended method for the diagnosis of clonality in lymphoproliferative disorders. It would allow pathologists to differentiate lymphoma from polyclonal lymphoid proliferation and to provide information for cell lineage.