CXCL12-CXCR4 Axis Is Required for Contact-Mediated Human B Lymphoid and Plasmacytoid Dendritic Cell Differentiation but Not T Lymphoid Generation

ACKR3 in Skin Homeostasis, an Overlooked Player in the CXCR4/CXCL12 Axis

CXCL12 and its receptor CXCR4 emerge as critical regulators within the intricate network of processes ensuring skin homeostasis. In this review, we discuss their spatial distribution and function in steady-state skin; delve into their role in acute wound healing, with emphasis on fibrotic and regenerative responses; and explore their relevance in skin responses to commensals and pathogens. Given the lack of knowledge surrounding ACKR3, the atypical receptor of CXCL12, we speculate whether and how it might be involved in the processes mentioned earlier. Is ACKR3 the (a)typical friend who enjoys missing the party, or do we need to take a closer look?

Optimizing in vitro T cell differentiation by using induced pluripotent stem cells with GFP-RUNX1 and mCherry-TCF7 labelling

In vitro T-cell differentiation from pluripotent stem cells (PSCs) could potentially provide an unlimited source of T cells for cancer immunotherapy, which, however is still hindered by the inefficient obtaining functionally-matured, terminally-differentiated T cells. Here, we established a fluorescence reporter human induced pluripotent stem cell (iPSC) line termed TCF7mCherryRUNX1GFP, in which the endogenous expression of RUNX1 and TCF7 are illustrated by the GFP and mCherry fluorescence, respectively. Utilizing TCF7mCherryRUNX1GFP, we defined that the feeder cells incorporating CXCL12-expressing OP9 cells with DL4-expressing OP9 cells at a 1:3 ratio (OP9-C1D3) significantly enhanced efficiency of CD8+ T cell differentiation from PSCs. Additionally, we engineered a chimeric antigen receptor (CAR) targeting EGFR into iPSCs. The CAR-T cells differentiated from these iPSCs using OP9-C1D3 feeders demonstrated effective cytotoxicity toward lung cancer cells. We anticipate this platform will help the in vitro HSPC and T cell differentiation optimization, serving the clinical demands of these cells.

A self-assembled graphene oxide adjuvant induces both enhanced humoral and cellular immune responses in influenza vaccine

Antiviral vaccine is essential for preventing and controlling virus spreading, along with declining morbidity and mortality. A major challenge in effective vaccination lies in the ability to enhance both the humoral and cellular immune responses by adjuvants. Herein, self-assembled nanoparticles based on graphene oxide quantum dots with components of carnosine, resiquimod and Zn2+ ions, namely ZnGC-R, are designed as a new adjuvant for influenza vaccine. With its high capability for antigen-loading, ZnGC-R enhances antigen utilization, improves DC recruitment, and activates antigen-presenting cells. Single cell analysis of lymphocytes after intramuscular vaccination revealed that ZnGC-R generated multifaceted immune responses. ZnGC-R stimulated robust CD4+CCR7loPD-1hi Tfh and durable CD8+CD44hiCD62L- TEM immune responses, and simultaneously promoted the proliferation of CD26+ germinal center B cells. Besides, ZnGC-R elicited 2.53-fold higher hemagglutination-inhibiting antibody than commercial-licensed aluminum salt adjuvant. ZnGC-R based vaccine induced 342% stronger IgG antibody responses compared with vaccines with inactivated virus alone, leading to 100% in vivo protection efficacy against the H1N1 influenza virus challenge.

N6-methyladenosine-methylomic landscape of lung tissues of mice with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a common respiratory disease, can be divided into stable phase and acute exacerbation phase (AECOPD) and is characterized by inflammation and hyper-immunity. Methylation of N6-methyladenosine (m6A) is an epigenetic modification that regulates the expression and functions of genes by influencing post-transcriptional RNA modifications. Its influence on the immune regulation mechanism has attracted great attention. Herein, we present the m6Amethylomic landscape and observe how the methylation of m6A participates in the pathological process of COPD. The m6A modification of 430 genes increased and that of 3995 genes decreased in the lung tissues of mice with stable COPD. The lung tissues of mice with AECOPD exhibited 740 genes with hypermethylated m6A peak and 1373 genes with low m6A peak. These differentially methylated genes participated in signaling pathways related to immune functions. To further clarify the expression levels of differentially methylated genes, RNA immunoprecipitation sequencing (MeRIP-seq) and RNA-sequencing data were jointly analyzed. In the stable COPD group, 119 hypermethylated mRNAs (82 upregulated and 37 downregulated mRNAs) and 867 hypomethylated mRNAs (419 upregulated and 448 downregulated mRNAs) were differentially expressed. In the AECOPD group, 87 hypermethylated mRNAs (71 upregulated and 16 downregulated mRNAs) and 358 hypomethylated mRNAs (115 upregulated and 243 downregulated mRNAs) showed differential expression. Many mRNAs were related to immune function and inflammation. Together, this study provides important evidence on the role of RNA methylation of m6A in COPD.

The Monocytic Cell Line THP-1 as a Validated and Robust Surrogate Model for Human Dendritic Cells

We have implemented an improved, cost-effective, and highly reproducible protocol for a simple and rapid differentiation of the human leukemia monocytic cell line THP-1 into surrogates for immature dendritic cells (iDCs) or mature dendritic cells (mDCs). The successful differentiation of THP-1 cells into iDCs was determined by high numbers of cells expressing the DC activation markers CD54 (88%) and CD86 (61%), and the absence of the maturation marker CD83. The THP-1-derived mDCs are characterized by high numbers of cells expressing CD54 (99%), CD86 (73%), and the phagocytosis marker CD11b (49%) and, in contrast to THP-1-derived iDCs, CD83 (35%) and the migration marker CXCR4 (70%). Treatment of iDCs with sensitizers, such as NiSO4 and DNCB, led to high expression of CD54 (97%/98%; GMFI, 3.0/3.2-fold induction) and CD86 (64%/96%; GMFI, 4.3/3.2-fold induction) compared to undifferentiated sensitizer-treated THP-1 (CD54, 98%/98%; CD86, 55%/96%). Thus, our iDCs are highly suitable for toxicological studies identifying potential sensitizing or inflammatory compounds. Furthermore, the expression of CD11b, CD83, and CXCR4 on our iDC and mDC surrogates could allow studies investigating the molecular mechanisms of dendritic cell maturation, phagocytosis, migration, and their use as therapeutic targets in various disorders, such as sensitization, inflammation, and cancer.

A bifurcation concept for B-lymphoid/plasmacytoid dendritic cells with largely fluctuating transcriptome dynamics

Hematopoiesis was considered a hierarchical stepwise process but was revised to a continuous process following single-cell RNA sequencing. However, the uncertainty or fluctuation of single-cell transcriptome dynamics during differentiation was not considered, and the dendritic cell (DC) pathway in the lymphoid context remains unclear. Here, we identify human B-plasmacytoid DC (pDC) bifurcation as large fluctuating transcriptome dynamics in the putative B/NK progenitor region by dry and wet methods. By converting splicing kinetics into diffusion dynamics in a deep generative model, our original computational methodology reveals strong fluctuation at B/pDC bifurcation in IL-7Rα⁺ regions, and LFA-1 fluctuates positively in the pDC direction at the bifurcation. These expectancies are validated by the presence of B/pDC progenitors in the IL-7Rα⁺ fraction and preferential expression of LFA-1 in pDC-biased progenitors with a niche-like culture system. We provide a model of fluctuation-based differentiation, which reconciles continuous and discrete models and is applicable to other developmental systems.

Identification of CXCR4 Upregulation in Diffuse Large B-Cell Lymphoma Associated with Prognostic Significance and Clinicopathological Characteristics

Background

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous malignant lymphoma with distinct characteristics. Patients with treatment failure after the standard immunochemotherapy have worse prognosis, which implies the necessity to uncover novel targets. The C-X-C chemokine receptor 4 (CXCR4) overexpression has been identified in several hematopoietic malignancies. However, the expression signatures and prognostic significance of CXCR4 in DLBCL associated with clinicopathological features remain unclear.

Methods

Gene expression profiles of DLBCL were obtained from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Then, a meta-analysis with an integrated bioinformatic analysis was performed to assess the relationship between CXCR4 expression and clinicopathological features of DLBCL. Finally, experimental verification including immunohistochemical (IHC) staining and real-time quantitative PCR (qPCR) was carried out using patient samples. In vitro cell line viability tests were conducted using CXCR4 inhibitor WZ811.

Results

DLBCL patients with activated B-cell-like (ABC) subtype have higher expression level of CXCR4 with worse survival. Differential expressed genes in the CXCR4-upregulation group were enriched in canonical pathways associated with oncogenesis. DLBCL with CXCR4 upregulation had lower degree of CD8⁺ T cell infiltration. TIMER analysis demonstrated that the CXCR4 expression was positively correlated with the expression of CD5, MYC, NOTCH1, PDCD1, CD274, mTOR, FOXO1, and hnRNPA2B1 in DLBCL. IHC study in patient samples showed the positive correlation between CXCR4 and nongerminal center B-cell (non-GCB) subtype and mTOR expression. Meanwhile, quantitative polymerase chain reaction results revealed that high CXCR4 mRNA level was correlated to double-hit DLBCL. Finally, cell viability test showed that WZ811 exerted antiproliferation effect in DLBCL cell lines in a dose-dependent manner.

Conclusion

CXCR4 was upregulated in ABC-DLBCL associated with worse prognosis. Our analysis predicted CXCR4 as a potential target for DLBCL treatment, which may serve as an inhibitor both on BCR signaling and nuclear export warranting further investigation in clinical trials.

A Selective Neutraligand for CXCL12/SDF-1α With Beneficial Regulatory Functions in MRL/Lpr Lupus Prone Mice

Dysregulation of CXCL12/SDF-1-CXCR4/CD184 signaling is associated with inflammatory diseases and notably with systemic lupus erythematosus. Issued from the lead molecule chalcone-4, the first neutraligand of the CXCL12 chemokine, LIT-927 was recently described as a potent analogue with improved solubility and stability. We aimed to investigate the capacity of LIT-927 to correct immune alterations in lupus-prone MRL/lpr mice and to explore the mechanism of action implemented by this small molecule in this model. We found that in contrast to AMD3100, an antagonist of CXCR4 and agonist of CXCR7, LIT-927 reduces the excessive number of several B/T lymphocyte subsets occurring in the blood of sick MRL/lpr mice (including CD3⁺/CD4^-/CD8^-/B220⁺ double negative T cells). In vitro, LIT-927 downregulated the overexpression of several activation markers on splenic MRL/lpr lymphocytes. It exerted effects on the CXCR4 pathway in MRL/lpr CD4⁺ T spleen cells. The results underline the importance of the CXCL12/CXCR4 axis in lupus pathophysiology. They indicate that neutralizing CXCL12 by the neutraligand LIT-927 can attenuate hyperactive lymphocytes in lupus. This mode of intervention might represent a novel strategy to control a common pathophysiological mechanism occurring in inflammatory diseases.

CD303 (BDCA-2) - a potential novel target for therapy in hematologic malignancies

Plasmacytoid dendritic cells (pDCs) serve as immunoregulatory antigen-presenting cells that play a role in various inflammatory, viral, and malignant conditions. Malignant proliferation of pDCs is implicated in the pathogenesis of certain hematologic cancers, specifically blastic plasmacytoid dendritic cell neoplasm (BPDCN) and acute myelogenous leukemia with clonal expansion of pDC (pDC-AML). In recent years, BPDCN and pDC-AML have been successfully treated with targeted therapy of pDC-specific surface marker, CD123. However, relapsed and refractory BPDCN remains an elusive cancer, with limited therapeutic options. CD303 is another specific surface marker of human pDCs, centrally involved in antigen presentation and immune tolerance. Monoclonal antibodies directed against CD303 have been studied in preclinical models and have achieved disease control in patients with cutaneous lupus erythematosus. We performed a comprehensive review of benign and malignant disorders in which CD303 have been studied, as there may be a potential future CD303-directed therapy for many of these conditions.

CXCR4 signaling controls dendritic cell location and activation at steady state and in inflammation

Dendritic cells (DCs) encompass several cell subsets that collaborate to initiate and regulate immune responses. Proper DC localization determines their function and requires the tightly controlled action of chemokine receptors. All DC subsets express CXCR4, but the genuine contribution of this receptor to their biology has been overlooked. We addressed this question using natural CXCR4 mutants resistant to CXCL12-induced desensitization and harboring a gain of function that cause the warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome (WS), a rare immunodeficiency associated with high susceptibility to the pathogenesis of human papillomavirus (HPV). We report a reduction in the number of circulating plasmacytoid DCs (pDCs) in WHIM patients, whereas that of conventional DCs is preserved. This pattern was reproduced in an original mouse model of WS, enabling us to show that the circulating pDC defect can be corrected upon CXCR4 blockade and that pDC differentiation and function are preserved, despite CXCR4 dysfunction. We further identified proper CXCR4 signaling as a critical checkpoint for Langerhans cell and DC migration from the skin to lymph nodes, with corollary alterations of their activation state and tissue inflammation in a model of HPV-induced dysplasia. Beyond providing new hypotheses to explain the susceptibility of WHIM patients to HPV pathogenesis, this study shows that proper CXCR4 signaling establishes a migration threshold that controls DC egress from CXCL12-containing environments and highlights the critical and subset-specific contribution of CXCR4 signal termination to DC biology.

Lactoferrin is required for early B cell development in C57BL/6 mice

Lactoferrin (Lf) is widely distributed in mammalian milk, various tissues, and their exocrine fluids and has many physiological functions, such as bacteriostasis, antivirus, and immunoregulation. Here, we provide evidence that lactoferrin is required for early stages of B cell development in mice. Lactoferrin-deficient (Lf^−/−) C57BL/6 mice showed systematic reduction in total B cells, which was attributed to the arrest of early B cell development from pre-pro-B to pro-B stage. Although the Lf^−/− B cell “seeds” generated greater pro-B cells comparing to wild type (WT) littermates, the Lf^−/− mice bone marrow had less stromal cells, and lower CXCL12 expression, produced a less favorable “microenvironment” for early B cell development. The underlying mechanism was mediated through ERK and AKT signalings and an abnormality in the transcription factors related to early differentiation of B cells. The Lf^−/− mice also displayed abnormal antibody production in T cell-dependent and T cell-independent immunization experiments. In a pristane-induced lupus model, Lf^−/− mice had more serious symptoms than WT mice, whereas lactoferrin treatment alleviated these symptoms. This study demonstrates a novel role of lactoferrin in early B cell development, suggesting a potential benefit for using lactoferrin in B cell-related diseases.

Differential mast cell phenotypes in benign versus cancer tissues and prostate cancer oncologic outcomes

We reported previously that high numbers of mast cells in benign (extra-tumoral) regions of the prostate are associated with worse outcomes after radical prostatectomy including biochemical recurrence and the development of metastases. Herein, with a cohort of 384 men, we performed mast cell subtyping and report that higher minimum number of the tryptase-only (MC_T ) subset of extra-tumoral mast cells is associated with increased risk of biochemical recurrence (comparing highest to lowest tertiles: HR 2.32, 95% CI 1.37-3.93; P-trend = 0.002), metastases (HR 3.62, 95% CI 1.75-7.47; P-trend 0.001), and death from prostate cancer (HR 2.87, 95% CI 1.19-6.95; P-trend = 0.02). Preliminary RNA sequencing and comparison of benign versus cancer tissue mast cells revealed differential expression of additional site-specific genes. We further demonstrate that the genes CXCR4 and TFE3 are more highly expressed in tumor-infiltrating mast cells as well as other tumor-infiltrating immune cells and in tumor cells, respectively, and represent an altered tumor microenvironment. KIT variants were also differentially expressed in benign versus cancer tissue mast cells, with KIT variant 1 (GNNK⁺ ) mast cells identified as more prevalent in extra-tumoral regions of the prostate. Finally, using an established mouse model, we found that mast cells do not infiltrate Hi-Myc tumors, providing a model to specifically examine the role of extra-tumoral mast cells in tumorigenesis. Hi-Myc mice crossed to mast cell knockout (Wsh) mice and aged to 1 year revealed a higher degree of pre-invasive lesions and invasive cancer in wild-type mice versus heterozygous and knockout mice. This suggests a dosage effect where higher numbers of extra-tumoral mast cells resulted in higher cancer invasion. Overall, our studies provide further evidence for a role of extra-tumoral mast cells in driving adverse prostate cancer outcomes. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Transcriptomic profiling of bovine blood dendritic cells and monocytes following TLR stimulation

Dendritic cells (DC) and monocytes are vital for the initiation of innate and adaptive immune responses. Recently, we identified bona fide DC subsets in blood of cattle, revealing subset- and species-specific transcription of toll-like receptors (TLR). In the present study, we analyzed phenotypic and transcriptional responses of bovine DC subsets and monocytes to in vitro stimulation with four to six different TLR ligands. Bovine DC subsets, especially plasmacytoid DC (pDC), showed a clear increase of CCR7, CD25, CD40, CD80, CD86, and MHC-II expression both on mRNA and protein level. Flow cytometric detection of p38 MAPK phosphorylation 15 min after stimulation confirmed activation of DC subsets and monocytes in accordance with TLR gene expression. Whole-transcriptome sequencing of sorted and TLR-stimulated subsets revealed potential ligand- and subset-specific regulation of genes associated with inflammation, T-cell co-stimulation, migration, metabolic reprogramming, and antiviral activity. Gardiquimod was found to evoke strong responses both in DC subsets and monocytes, while Poly(I:C) and CpG preferentially triggered responses in cDC1 and pDC, respectively. This in-depth analysis of ligand responsiveness is essential for the rational design of vaccine adjuvants in cattle, and provides a solid basis for comparative studies on DC and monocyte biology across species.

Renal papillary tip extract stimulates BNP production and excretion from cardiomyocytes

BACKGROUND

Brain natriuretic peptide (BNP) is an important biomarker for patients with cardiovascular diseases, including heart failure, hypertension and cardiac hypertrophy. It is also known that BNP levels are relatively higher in patients with chronic kidney disease and no heart disease; however, the mechanism remains unclear.

METHODS AND RESULTS

We developed a BNP reporter mouse and occasionally found that this promoter was activated specifically in the papillary tip of the kidneys, and its activation was not accompanied by BNP mRNA expression. No evidence was found to support the existence of BNP isoforms or other nucleotide expression apart from BNP and tdTomato. The pBNP-tdTomato-positive cells were interstitial cells and were not proliferative. Unexpectedly, both the expression and secretion of BNP increased in primary cultured neonatal cardiomyocytes after their treatment with an extract of the renal papillary tip. Intraperitoneal injection of the extract of the papillary tips reduced blood pressure from 210 mmHg to 165 mmHg, the decrease being accompanied by an increase in serum BNP and urinary cGMP production in stroke-prone spontaneously hypertensive (SHR-SP) rats. Furthermore the induction of BNP by the papillary extract from rats with heart failure due to myocardial infarction was increased in cardiomyocytes.

CONCLUSIONS

These results suggested that the papillary tip express a substance that can stimulate BNP production and secretion from cardiomyocytes.