Foxo3 Promotes Apoptosis of B Cell Receptor-Stimulated Immature B Cells, Thus Limiting the Window for Receptor Editing

Increased B Cell Understanding Puts Improved Vaccine Platforms Just Over the Horizon

In the face of an endlessly expanding repertoire of Ags, vaccines are constantly being tested, each more effective than the last. As viruses and other pathogens evolve to become more infectious, the need for efficient and effective vaccines grows daily, which is especially obvious in an era that is still attempting to remove itself from the clutches of the severe acute respiratory syndrome coronavirus 2, the cause of coronavirus pandemic. To continue evolving alongside these pathogens, it is proving increasingly essential to consider one of the main effector cells of the immune system. As one of the chief orchestrators of the humoral immune response, the B cell and other lymphocytes are essential to not only achieving immunity, but also maintaining it, which is the vital objective of every vaccine.

B Cell Activation Results in IKK-Dependent, but Not c-Rel- or RelA-Dependent, Decreases in Transcription of the B Cell Tolerance-Inducing Gene Ets1

Ets1 is a key transcription factor in B cells that is required to prevent premature differentiation into Ab-secreting cells. Previously, we showed that BCR and TLR signaling downregulate Ets1 levels and that the kinases PI3K, Btk, IKK, and JNK are required for this process. PI3K is important in activating Btk by generating the membrane lipid phosphatidylinositol (3,4,5)-trisphosphate, to which Btk binds via its PH domain. Btk in turn is important in activating the IKK kinase pathway, which it does by activating phospholipase Cγ2→protein kinase Cβ signaling. In this study, we have further investigated the pathways regulating Ets1 in mouse B cells. Although IKK is well known for its role in activating the canonical NF-κB pathway, IKK-mediated downregulation of Ets1 does not require either RelA or c-Rel. We also examined the potential roles of two other IKK targets that are not part of the NF-κB signaling pathway, Foxo3a and mTORC2, in regulating Ets1. We find that loss of Foxo3a or inhibition of mTORC2 does not block BCR-induced Ets1 downregulation. Therefore, these two pathways are not key IKK targets, implicating other as yet undefined IKK targets to play a role in this process.

FoxO1 suppresses IL-10 producing B cell differentiation via negatively regulating Blimp-1 expression and contributes to allergic asthma progression

IL-10-producing B cells (B10) are involved in the prevention of autoimmune and allergic responses but its mechanisms remain poorly understood. We took advantage of the ovalbumin-induced asthma mouse model to demonstrate that the activity of FoxO1 is upregulated in lung B cells and correlates inversely with B10 cells, while showing decreased activity in ex vivo and in vitro induced B10 cells. We further observed that FoxO1 deficiency leads to increased frequency of B10 cells. These observations have in vivo clinical evidence, as B cell specific FoxO1 deficiency leads to reduced lung eosinophils and asthma remission in mice, and there are reduced regulatory B cells and increased FoxO1 activity in B cells of asthma patients. Single cell RNA-sequencing data demonstrated a negative correlation between the expression of Foxo1 and Il10 in B cells from the mouse spleen and lung and the human lung. For a biological mechanism, FoxO1 inhibits the expression of Prdm1, which encodes Blimp-1, a transcription factor of B10 cells. Our experimental evidence in both murine and human asthma demonstrates that FoxO1 is a negative regulator of B10 cell differentiation via negatively regulating Prdm1 and its expression in B cells contributes to allergic asthma disease.

Regulatory Non-Coding RNAs Modulate Transcriptional Activation During B Cell Development

B cells play a significant role in the adaptive immune response by secreting immunoglobulins that can recognize and neutralize foreign antigens. They develop from hematopoietic stem cells, which also give rise to other types of blood cells, such as monocytes, neutrophils, and T cells, wherein specific transcriptional programs define the commitment and subsequent development of these different cell lineages. A number of transcription factors, such as PU.1, E2A, Pax5, and FOXO1, drive B cell development. Mounting evidence demonstrates that non-coding RNAs, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), modulate the expression of these transcription factors directly by binding to the mRNA coding for the transcription factor or indirectly by modifying cellular pathways that promote expression of the transcription factor. Conversely, these transcription factors upregulate expression of some miRNAs and lncRNAs to determine cell fate decisions. These studies underscore the complex gene regulatory networks that control B cell development during hematopoiesis and identify new regulatory RNAs that require additional investigation. In this review, we highlight miRNAs and lncRNAs that modulate the expression and activity of transcriptional regulators of B lymphopoiesis and how they mediate this regulation.

Association of FOXO3a gene polymorphisms and ankylosing spondylitis susceptibility in Eastern Chinese Han population

OBJECTIVE

To investigate the association of FOXO3a polymorphisms and ankylosing spondylitis (AS) susceptibility in Eastern Chinese Han population.

METHODS

FOXO3a polymorphisms rs12206094, rs12212067, rs2253310, rs3800232, and rs4946933 were genotyped in 650 AS patients and 646 controls by the improved Multiple Ligase Detection Reaction.

RESULTS

The distribution of genotype in rs12212067 polymorphism was significantly different between AS patients and controls (P = 0.020), especially in male population (P = 0.009). There was significant difference of the genotype frequency distribution at rs3800232 between patients and controls in male population. The results of binary regression analysis showed that the rs12212067 GG genotype and rs3800232 TT genotype were obviously correlated with elevated AS risk, and the associations were still significant after being adjusted by age and gender (all P < 0.05). Interestingly, rs12212067 and rs3800232 genotypes were associated with disease activity of patients. Additionally, haplotype block rs12212067^G- rs3800232^T (OR = 1.403, 95%CI = 1.011-1.949) was further shown to confer promoting effect on developing AS.

CONCLUSION

Among Eastern Chinese Han population, FOXO3a polymorphism rs12212067 and rs3800232 may contribute to increased risk of developing AS, but well-designed multicenter studies are needed to further confirm these preliminary findings in the future.

RNA Methylation in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with complicated clinical manifestations. Although our understanding of the pathogenesis of SLE has greatly improved, the understanding of the pathogenic mechanisms of SLE is still limited by disease heterogeneity, and targeted therapy is still unavailable. Substantial evidence shows that RNA methylation plays a vital role in the mechanisms of the immune response, prompting speculation that it might also be related to the occurrence and development of SLE. RNA methylation has been a hot topic in the field of epigenetics in recent years. In addition to revealing the modification process, relevant studies have tried to explore the relationship between RNA methylation and the occurrence and development of various diseases. At present, some studies have provided evidence of a relationship between RNA methylation and SLE pathogenesis, but in-depth research and analysis are lacking. This review will start by describing the specific mechanism of RNA methylation and its relationship with the immune response to propose an association between RNA methylation and SLE pathogenesis based on existing studies and then discuss the future direction of this field.

Role of Forkhead box O3a transcription factor in autoimmune diseases

Forkhead box O3a (FOXO3a) transcription factor, the most important member of Forkhead box O family, is closely related to cell proliferation, apoptosis, autophagy, oxidative stress and aging. The downregulation of FOXO3a has been verified to be associated with the poor prognosis, severer malignancy and chemoresistance in several human cancers. The activity of FOXO3a mainly regulated by phosphorylation of protein kinase B. FOXO3a plays a vital role in promoting the apoptosis of immune cells. FOXO3a could also modulate the activation, differentiation and function of T cells, regulate the proliferation and function of B cells, and mediate dendritic cells tolerance and immunity. FOXO3a accommodates the immune response through targeting nuclear factor kappa-B and FOXP3, as well as regulating the expression of cytokines. Besides, FOXO3a participates in intercellular interactions. FOXO3a inhibits dendritic cells from producing interleukin-6, which inhibits B-cell lymphoma-2 (BCL-2) and BCL-XL expression, thereby sparing resting T cells from apoptosis and increasing the survival of antigen-stimulated T cells. Recently, plentiful evidences further illustrated the significance of FOXO3a in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, ankylosing spondylitis, myositis, multiple sclerosis, and systemic sclerosis. In this review, we focused on the biological function of FOXO3a and related signaling pathways regarding immune system, and summarized the potential role of FOXO3a in the pathogenesis, progress and therapeutic potential of autoimmune diseases.

Proliferation and Apoptosis of B-Cell Lymphoma Cells under Targeted Regulation of FOXO3 by miR-155

This study aimed to explore B-cell lymphoma cells' proliferation and apoptosis under targeted regulation of FOXO3 by miR-155. We analyzed the differences between B-cell lymphoma cells and B lymphocytes in expressions of miR-155 and FOXO3, explored the effects of miR-155 on proliferation and apoptosis of B-cell lymphoma cells, and relevant mechanisms, and also analyzed the relationship between expressions of miR-155 and FOXO3 in 42 patients with diffuse large B-cell lymphoma (DLBCL) and clinical characteristics of them. B-cell lymphoma cells showed a higher expression of miR-155 and a low expression of FOXO3 than B lymphocytes (both P<0.05). B-cell lymphoma cells transfected with miR-155-inhibitor showed significantly decreased expression of miR-155, significantly weakened cell proliferation ability, and increased cell apoptosis rate (all P<0.05), and they also showed upregulated expression of FOXO3 (P<0.05). Dual-luciferase reporter assay revealed that there were targeted binding sites between miR-155 and FOXO3. Compared with B-cell lymphoma cells transfected with miR-155-inhibitor alone, those with co-transfection showed lower expression of FOXO3, higher proliferation and lower cell apoptosis rate (all P<0.05). The expression of miR-155 in DLBCL tissues was higher than that in tumor-adjacent tissues (P<0.05), and the expressions of miR-155 and FOXO3 were closely related to the international prognostic index (IPI) and the 5-year prognosis and survival of the patients (P<0.05). miR-155 can promote the proliferation of B-cell lymphoma cells and suppress apoptosis of them by targeted inhibition of FOCXO3, and both over-expression of miR-155 and low expression of FOXO3 are related to poor prognosis of DLBCL patients.