NDRG1 is induced by antigen-receptor signaling but dispensable for B and T cell self-tolerance

Ndrg3 is a critical regulator of peripheral T cell maturation and homeostasis

To provide protection, anticipatory T cell-dependent immunity is reliant on the generation and maintenance of a naïve T cell repertoire, which is sufficiently diverse to ensure recognition of newly encountered antigens. Therefore, under steady-state conditions, a given individual needs to maintain a large pool of naïve T cells, ready to respond to potential threats. Here, we demonstrate that N-myc downstream-regulated gene 3 (Ndrg3) is essential for naïve T cell stability. Mice with T cell-specific Ndrg3 loss are lymphopenic, with reduced numbers of conventional T cells and natural killer T cells. We show that in the absence of Ndrg3, naïve CD8+ T cells exhibit high rates of both proliferation and apoptosis, phenotypes that could be partially rescued by transgenic expression of a high-avidity T cell receptor. Furthermore, Ndrg3-deficient cells were refractory to interleukin-4, resulting in reduced Eomes induction, and a decreased virtual memory population. Our study therefore identifies Ndrg3 as an unexpected, pleiotropic regulator of T cell homeostasis.

POU2F2 activates the Akt/mTOR signalling pathway and enhances B lymphocyte function during diabetic kidney disease by promoting PIK3CD transcription

BACKGROUND

Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta (PIK3CD) is the predominant isoform of the catalytic subunit of PI3K in lymphocytes. Based on comprehensive bioinformatics, this study explores the functions of PIK3CD in diabetic kidney disease (DKD) progression in mice and B lymphocyte activity.

METHODS

Non-obese diabetic (NOD) mice that spontaneously develop DKD were applied as animal models. Lentiviral vector-mediated PIK3CD silencing was introduced in mice, followed by histological staining and biomarker assessments to evaluate DKD-associated symptoms. The activity of the Akt/mTOR signalling pathway was determined by western blot analysis. Following bioinformatics analyses, the interaction between POU class 2 homeobox 2 (POU2F2) and PIK3CD in B lymphocytes was determined by chromatin immunoprecipitation and luciferase reporter assays. Their functions in B cell function were identified by MTT, flow cytometry and IgG deposition assessment.

RESULTS

PIK3CD was found to be highly expressed in the kidney of DKD mice. Knockdown of PIK3CD inactivated the Akt/mTOR signalling, thus ameliorating tissue injury and fibrosis, enhancing the expression of AQP1 and decreasing urinary NGAL contents, UACR, BUN and β-NAG/creatinine ratio. These effects were negated by the Akt-specific activator SC79. POU2F2 was found to promote PIK3CD transcription by binding to its promoter, thus activating the Akt/mTOR pathway. Knockdown of POU2F2 suppressed B cell proliferation in vitro and decreased B cell population and IgG deposition in the mouse kidney. However, these trends were reversed upon additional PIK3CD overexpression.

CONCLUSION

This study demonstrates that POU2F2 mediates PIK3CD-dependent Akt/mTOR signalling activation, thus enhancing B lymphocyte function and promoting DKD progression.

NDRG1 overcomes resistance to immunotherapy of pancreatic ductal adenocarcinoma through inhibiting ATG9A-dependent degradation of MHC-1

AIMS

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease that is resistant to immune checkpoint blockade (ICB) therapies. Emerging evidence suggests that NDRG1 may be an important target for the development of new therapies for PDAC. Herein, we investigated the novel roles of NDRG1 and Combretastatin A-4 (CA-4) in the treatment of PDAC ICB resistance.

METHODS

Enrichment of MHC class I was detected by RNA sequence and verified by RT-qPCR and immunoblotting in NDRG1-knockdown human pancreatic cancer cell lines. The protein degradation mode was found by stimulation with various inhibitors, and the autophagy degradation pathway was found by immunoprecipitation and immunolocalization. The roles of NDRG1 and MHC-I in immunotherapy were investigated by orthotopic solid tumors, histology, immunohistochemistry, multiplex immunofluorescence staining and flow cytometry.

RESULTS

Here, we identified a previously undescribed role of NDRG1 in activating major histocompatibility complex class 1 (MHC-1) expression in pancreatic ductal adenocarcinoma (PDAC) cells through lysosomal-autophagy-dependent degradation. In mouse models of PDAC, either tumor cell overexpression or pharmacologic activation of NDRG1 leads to MHC-1 upregulation in tumor cells, which in turn promotes the infiltration and activity of CD8 + T cells, enhances anti-tumor immunity, and overcomes resistance to ICB therapy. Moreover, combination therapy of CA-4 and ICB overcomes the drug resistance of pancreatic cancer to ICB therapy. In PDAC patients, NDRG1 expression correlates with high MHC-1 expression and better survival.

CONCLUSION

Our results reveal NDRG1 in PDAC cancer cells as a tumor suppressor and suggest that pharmaceutically targeting NDRG1 is a promising way to overcome pancreatic cancer resistance to immunotherapy and provides a potential therapeutic strategy for the treatment of pancreatic cancer patients.

Upregulated Fcrl5 disrupts B cell anergy and causes autoimmune disease

B cell anergy plays a critical role in maintaining self-tolerance by inhibiting autoreactive B cell activation to prevent autoimmune diseases. Here, we demonstrated that Fc receptor-like 5 (Fcrl5) upregulation contributes to autoimmune disease pathogenesis by disrupting B cell anergy. Fcrl5-a gene whose homologs are associated with human autoimmune diseases-is highly expressed in age/autoimmunity-associated B cells (ABCs), an autoreactive B cell subset. By generating B cell-specific Fcrl5 transgenic mice, we demonstrated that Fcrl5 overexpression in B cells caused systemic autoimmunity with age. Additionally, Fcrl5 upregulation in B cells exacerbated the systemic lupus erythematosus-like disease model. Furthermore, an increase in Fcrl5 expression broke B cell anergy and facilitated toll-like receptor signaling. Thus, Fcrl5 is a potential regulator of B cell-mediated autoimmunity by regulating B cell anergy. This study provides important insights into the role of Fcrl5 in breaking B cell anergy and its effect on the pathogenesis of autoimmune diseases.