Search

Ubiquitin-specific peptidase 18 (USP18) plays an important role in the development of CD11b + dendritic cells (DCs) and Th17 cells, however, its role in the differentiation of other T cell subsets, especially in regulatory T (Treg) cells, is unknown. In our study, we used Usp18 KO mice to study the loss of USP18 on the impact of Treg cell differentiation and function. We found that USP18 deficiency upregulates the differentiation of Treg cells, which may lead to disrupted homeostasis of peripheral T cells, and downregulates INF-γ, IL-2, IL-17A producing CD4 + T cells and INF-γ producing CD8 + T cells. Mechanistically, we also found that the upregulation of Tregs is due to elevated expression of CD25 in Usp18 KO mice. Finally, we found that the suppressive function of Usp18 KO Tregs is downregulated. Altogether, our study was the first to identify the role of USP18 in Tregs differentiation and its suppressive function, which may provide a new reference for the treatment of Treg function in many autoimmune diseases, and USP18 can be used as a new therapeutic target for precise medical treatment.

Chemokines are important regulators of the immune system, inducing specific cellular responses by binding to receptors on immune cells. In SLE patients, decreased expression of CCL2 on mesenchymal stem cells (MSC) prevents inhibition of B-cell proliferation, causing the characteristic autoimmune phenotype. Nevertheless, the intrinsic role of CCL2 on B-cell autoimmunity is unknown. In this study using Ccl2 KO mice, we found that CCL2 deficiency enhanced BCR signaling by upregulating the phosphorylation of the MST1-mTORC1-STAT1 axis, which led to reduced marginal zone (MZ) B cells and increased germinal center (GC) B cells. The abnormal differentiation of MZ and GC B cells were rescued by in vivo inhibition of mTORC1. Additionally, the inhibition of MST1-mTORC1-STAT1 with specific inhibitors in vitro also rescued the BCR signaling upon antigenic stimulation. The deficiency of CCL2 also enhanced the early activation of B cells including B-cell spreading, clustering and signalosome recruitment by upregulating the DOCK8-WASP-actin axis. Our study has revealed the intrinsic role and underlying molecular mechanism of CCL2 in BCR signaling, B-cell differentiation, and humoral response.

In the original published version of the article, the red squares in the figures which indicated the corrections.

As an important chemokine receptor, the role of CX3CR1 has been studied extensively on the migration of lymphocytes including T and B cells. Although CX3CR1+ B cells have immune suppressor properties, little is known about its role on the regulation of BCR signaling and B cell differentiation as well as the underlying molecular mechanism. We have used CX3CR1 KO mice to study the effect of CX3CR1 deficiency on BCR signaling and B cell differentiation. Interestingly, we found that proximal BCR signaling, such as the activation of CD19, BTK and SHIP was reduced in CX3CR1 KO B cells upon antigenic stimulation. However, the activation of mTORC signaling was enhanced. Mechanistically, we found that the reduced BCR signaling in CX3CR1 KO B cells was due to reduced BCR clustering, which is caused by the enhanced actin accumulation by the plasma membrane via increased activation of WASP. This caused an increased differentiation of MZ B cells in CX3CR1 KO mice and an enhanced generation of plasma cells (PC) and antibodies. Our study shows that CX3CR1 regulates BCR signaling via actin remodeling and affects B cell differentiation and the humoral immune response.

Single-stage detectors depend on a simple regression network to predict category scores and regress box offsets for a fixed set of default boxes directly. The regression network needs to have high generalization capability, so as to accurately model the relationship between various object shapes and default boxes. Instead of complicating the regression network to increase generalization capability, we iteratively refine the default boxes to model this relationship sequentially. In this paper, we propose an Attention-Enhanced Progressive Learning Network (APLNet), which employs multiple stages for progressive detection to improve performance of single-stage detectors. Specifically, a progressive learning module is proposed to iteratively update the feature representation space and gradually regress the default boxes, which are pushed closer to the target objects progressively. In addition, since low-level features have less semantic information about objects, we design an attention enhancement module to generate the attention map applied to inject more semantically meaningful information into the low-level features. This module is supervised by boxes-induced segmentation annotations, i.e., no extra segmentation annotations are required. The multi-task loss function is used to train the whole network in an end-to-end way. Extensive experiments on PASCAL VOC 2007, PASCAL VOC 2012 and MS COCO datasets demonstrate the effectiveness of the proposed APLNet.

Background: Chemokine (C-C motif) receptor 2 (CCR2) contributes to autoimmune pathogenesis. However, the effect of CCR2 on B cell signaling and its role in autoimmunity remains unclear. Herein, we investigated the role of CCR2 in the B cell receptor (BCR) signaling pathway and aimed to illustrate its potential molecular mechanisms of action. Methods: To investigate the alterations in B cell signaling and the immune response, we used flow cytometry, western blotting, microscopic techniques, Seahorse assay, and immunofluorescence assay on samples from C57BL/6 mice and germinal CCR2-deletion mice. Results: The absence of CCR2 disturbed follicular B cell development. Furthermore, CCR2 absence was correlated with increased mTORC1-mediated energy metabolism and enhanced early B cell activation, which were induced by the up-regulation of BCR proximal signaling and F-actin accumulation. Mst1 and STAT1 were key factors in up-regulating the B cell activation in CCR2 deficient mice. The disrupted peripheral B cell differentiation and enhanced B cell signaling were associated with the inhibition mTORC1, Mst1, and STAT1. Moreover, loss of CCR2 caused a weakened T cell dependent antigen response, resulting in decreased antibody secreting cells and diminished antigen specific IgM levels. Conclusion: CCR2 is involved in the regulation of BCR signaling pathway by sequentially activating signaling pathways dominated by Mst1, mTORC1, and STAT1. Our study suggests that CCR2 might represent a novel therapeutic targeted for autoimmune diseases.

Dedicator of cytokinesis 2 (DOCK2) is essential for the B cell differentiation, BCR signaling and humoral immune response. However, the role of DOCK2 in the memory response of B cell is unknown. By using two DOCK2 deficient patients, we found that the memory B cells were decreased and the early activation of DOCK2 deficient memory B cells was abolished to the degree of naive B cells due to the decreased expression of CD19 and CD21 mechanistically. Interestingly the expression of LEF-1, a negative regulator of CD21, was increased in DOCK2 deficient B cells. This was linked to the increased expression of HIF-1α and cell metabolism, which in turn affected the ER structure. Finally, the reduction of memory B cells in DOCK2 patients was due to the increased apoptosis, which might be related with the increased metabolism.

These findings point to the mechanism of how STING regulates BCR signaling via feedback from actin reorganization., The adaptor protein, STING (stimulator of interferon genes), has been rarely studied in adaptive immunity. We used Sting KO mice and a patient’s mutated STING cells to study the effect of STING deficiency on B cell development, differentiation, and BCR signaling. We found that STING deficiency promotes the differentiation of marginal zone B cells. STING is involved in BCR activation and negatively regulates the activation of CD19 and Btk but positively regulates the activation of SHIP. The activation of WASP and accumulation of F-actin were enhanced in Sting KO B cells upon BCR stimulation. Mechanistically, STING uses PI3K mediated by the CD19-Btk axis as a central hub for controlling the actin remodeling that, in turn, offers feedback to BCR signaling. Overall, our study provides a mechanism of how STING regulates BCR signaling via feedback from actin reorganization, which contributes to positive regulation of STING on the humoral immune response.

Background B-cell receptor (BCR) signaling, combined with CD19 and CD21 signals, imparts specific control of B-cell responses. Dedicator of cytokinesis protein 2 (DOCK2) is critical for the migration and motility of lymphocytes. Although absence of DOCK2 leads to lymphopenia, little is known about the signaling mechanisms and physiologic functions of DOCK2 in B cells. Objective We sought to determine the underlying molecular mechanism of how DOCK2 regulates BCR signaling and peripheral B-cell differentiation. Methods In this study we used genetic models for DOCK2, Wiskott–Aldrich syndrome protein (WASP), and lymphoid enhancer–binding factor 1 deficiency to study their interplay in BCR signaling and B-cell differentiation. Results We found that the absence of DOCK2 led to downregulation of proximal and distal BCR signaling molecules, including CD19, but upregulation of SH2-containing inositol 5 phosphatase 1, a negative signaling molecule. Interestingly, DOCK2 deficiency reduced CD19 and CD21 expression at the mRNA and/or protein levels and was associated with reduced numbers of marginal zone B cells. Additionally, loss of DOCK2 reduced activation of WASP and accelerated degradation of WASP, resulting into reduced actin accumulation and early activation of B cells. Mechanistically, the absence of DOCK2 upregulates the expression of lymphoid enhancer–binding factor 1. These differences were associated with altered humoral responses in the absence of DOCK2. Conclusions Overall, our study has provided a novel underlying molecular mechanism of how DOCK2 deficiency regulates surface expression of CD21, which leads to downregulation of CD19-mediated BCR signaling and marginal zone B-cell differentiation.

As an adaptor protein, MITA has been extensively studied in innate immunity. However, its role in adaptive immunity as well as its underlying mechanism are not completely understood. We used MITA KO mice to study the effect of MITA deficiency on B cell development and differentiation, BCR signaling during BCR activation and humoral immune response. We found that MITA deficiency promotes the differentiation of marginal zone B cells, which is linked to the lupus-like autoimmune disease that develops in MITA KO mice. MITA is involved in BCR activation and negatively regulates the activation of CD19 and Btk and positively regulates the activation of SHIP. Interestingly, we found that the activation of WASP and accumulation of F-actin is enhanced in MITA KO B cells upon stimulation. Mechanistically, we found that MITA uses PI3K mediated by the CD19-Btk axis as a central hub to control the actin remodeling that, in turn, offers feedback to BCR signaling. Overall, our study has provided a new mechanism on how MITA regulates BCR signaling via feedback from actin reorganization, which may contribute to the effects of MITA on the humoral immune response.

Accurate and timely short-term traffic flow prediction plays an important role in intelligent transportation management and control. Traffic flow prediction has a long history and is still a difficult problem due to intrinsically highly nonlinear and stochastic characteristics of complex transportation systems. In this paper, we employ the long short-term memory (LSTM) recurrent neural network to analyze the effects of various input settings on the LSTM prediction performances. Flow, speed, and occupancy at the same detector station are used as inputs to predict traffic flow. The results show that the inclusion of occupancy/speed information may help to enhance the performance of the model overall. Further, we include as inputs traffic variables from the upstream and/or downstream detector stations for traffic flow prediction. The evaluation of such spatial-temporal input interactions show that the inclusion of both downstream and upstream traffic information is useful in improving prediction accuracy.