Conserved and Unique Functions of Blimp1 in Immune Cells

Epigenetic recording of stimulation history reveals BLIMP1-BACH2 balance in determining memory B cell fate upon recall challenge

Memory B cells (MBCs) differentiate into plasma cells (PCs) or germinal centers (GCs) upon antigen recall. How this decision is programmed is not understood. We found that the relative strength between two antagonistic transcription factors, B lymphocyte-induced maturation protein 1 (BLIMP1) and BTB domain and CNC homolog 2 (BACH2), progressively increases in favor of BLIMP1 in antigen-responding B cells through the course of primary responses. MBC subsets that preferentially produce secondary GCs expressed comparatively higher BACH2 but lower BLIMP1 than those predisposed for PC development. Skewing the BLIMP1-BACH2 balance in otherwise fate-predisposed MBC subsets could switch their fate preferences. Underlying the changing BLIMP1-over-BACH2 balance, we observed progressively increased accessibilities at chromatin loci that are specifically opened in PCs, particularly those that contain interferon-sensitive response elements (ISREs) and are controlled by interferon regulatory factor 4 (IRF4). IRF4 is upregulated by B cell receptor, CD40 or innate receptor signaling and it induces graded levels of PC-specifying epigenetic imprints according to the strength of stimulation. By analyzing history-stamped GC B cells, we found progressively increased chromatin accessibilities at PC-specific, IRF4-controlled gene loci over time. Therefore, the cumulative stimulation history of B cells is epigenetically recorded in an IRF4-dependent manner, determines the relative strength between BLIMP1 and BACH2 in individual MBCs and dictates their probabilities to develop into GCs or PCs upon restimulation.

Early-Life Supplementation Enhances Gastrointestinal Immunity and Microbiota in Young Rats

Immunonutrition, which focuses on specific nutrients in breast milk and post-weaning diets, plays a crucial role in supporting infants' immune system development. This study explored the impact of maternal supplementation with Bifidobacterium breve M-16V and a combination of short-chain galacto-oligosaccharide (scGOS) and long-chain fructo-oligosaccharide (lcFOS) from pregnancy through lactation, extending into the early childhood of the offspring. The synbiotic supplementation's effects were examined at both mucosal and systemic levels. While the supplementation did not influence their overall growth, water intake, or food consumption, a trophic effect was observed in the small intestine, enhancing its weight, length, width, and microscopic structures. A gene expression analysis indicated a reduction in FcRn and Blimp1 and an increase in Zo1 and Tlr9, suggesting enhanced maturation and barrier function. Intestinal immunoglobulin (Ig) A levels remained unaffected, while cecal IgA levels decreased. The synbiotic supplementation led to an increased abundance of total bacteria and Ig-coated bacteria in the cecum. The abundance of Bifidobacterium increased in both the intestine and cecum. Short-chain fatty acid production decreased in the intestine but increased in the cecum due to the synbiotic supplementation. Systemically, the Ig profiles remained unaffected. In conclusion, maternal synbiotic supplementation during gestation, lactation, and early life is established as a new strategy to improve the maturation and functionality of the gastrointestinal barrier. Additionally, it participates in the microbiota colonization of the gut, leading to a healthier composition.

Human and Murine Toll-like Receptor-Driven Disease in Systemic Lupus Erythematosus

The pathogenesis of systemic lupus erythematosus (SLE) is linked to the differential roles of toll-like receptors (TLRs), particularly TLR7, TLR8, and TLR9. TLR7 overexpression or gene duplication, as seen with the Y-linked autoimmune accelerator (Yaa) locus or TLR7 agonist imiquimod, correlates with increased SLE severity, and specific TLR7 polymorphisms and gain-of-function variants are associated with enhanced SLE susceptibility and severity. In addition, the X-chromosome location of TLR7 and its escape from X-chromosome inactivation provide a genetic basis for female predominance in SLE. The absence of TLR8 and TLR9 have been shown to exacerbate the detrimental effects of TLR7, leading to upregulated TLR7 activity and increased disease severity in mouse models of SLE. The regulatory functions of TLR8 and TLR9 have been proposed to involve competition for the endosomal trafficking chaperone UNC93B1. However, recent evidence implies more direct, regulatory functions of TLR9 on TLR7 activity. The association between age-associated B cells (ABCs) and autoantibody production positions these cells as potential targets for treatment in SLE, but the lack of specific markers necessitates further research for precise therapeutic intervention. Therapeutically, targeting TLRs is a promising strategy for SLE treatment, with drugs like hydroxychloroquine already in clinical use.

Tyrosine kinase 2 modulates splenic B cells through type I IFN and TLR7 signaling

Tyrosine kinase 2 (TYK2) is involved in type I interferon (IFN-I) signaling through IFN receptor 1 (IFNAR1). This signaling pathway is crucial in the early antiviral response and remains incompletely understood on B cells. Therefore, to understand the role of TYK2 in B cells, we studied these cells under homeostatic conditions and following in vitro activation using Tyk2-deficient (Tyk2-/-) mice. Splenic B cell subpopulations were altered in Tyk2-/- compared to wild type (WT) mice. Marginal zone (MZ) cells were decreased and aged B cells (ABC) were increased, whereas follicular (FO) cells remained unchanged. Likewise, there was an imbalance in transitional B cells in juvenile Tyk2-/- mice. RNA sequencing analysis of adult MZ and FO cells isolated from Tyk2-/- and WT mice in homeostasis revealed altered expression of IFN-I and Toll-like receptor 7 (TLR7) signaling pathway genes. Flow cytometry assays corroborated a lower expression of TLR7 in MZ B cells from Tyk2-/- mice. Splenic B cell cultures showed reduced proliferation and differentiation responses after activation with TLR7 ligands in Tyk2-/- compared to WT mice, with a similar response to lipopolysaccharide (LPS) or anti-CD40 + IL-4. IgM, IgG, IL-10 and IL-6 secretion was also decreased in Tyk2-/- B cell cultures. This reduced response of the TLR7 pathway in Tyk2-/- mice was partially restored by IFNα addition. In conclusion, there is a crosstalk between TYK2 and TLR7 mediated by an IFN-I feedback loop, which contributes to the establishment of MZ B cells and to B cell proliferation and differentiation.

Children with perinatally acquired HIV exhibit distinct immune responses to 4CMenB vaccine

Children with perinatally acquired HIV (PHIV) have special vaccination needs, as they make suboptimal immune responses. Here, we evaluated safety and immunogenicity of 2 doses of 4-component group B meningococcal vaccine in antiretroviral therapy-treated children with PHIV and healthy controls (HCs). Assessments included the standard human serum bactericidal antibody (hSBA) assay and measurement of IgG titers against capsular group B Neisseria meningitidis antigens (fHbp, NHBA, NadA). The B cell compartment and vaccine-induced antigen-specific (fHbp+) B cells were investigated by flow cytometry, and gene expression was investigated by multiplexed real-time PCR. A good safety and immunogenicity profile was shown in both groups; however, PHIV demonstrated a reduced immunogenicity compared with HCs. Additionally, PHIV showed a reduced frequency of fHbp+ and an altered B cell subset distribution, with higher fHbp+ frequency in activated memory and tissue-like memory B cells. Gene expression analyses on these cells revealed distinct mechanisms between PHIV and HC seroconverters. Overall, these data suggest that PHIV presents a diverse immune signature following vaccination. The impact of such perturbation on long-term maintenance of vaccine-induced immunity should be further evaluated in vulnerable populations, such as people with PHIV.

Investigation and drug design for novel molecules from natural products as inhibitors for controlling multiple myeloma disease using in-silico tools

Multiple myeloma (MM) is a disease that causes plasma cell growth in the bone marrow and immune globulin buildup in blood and urine. Despite recent advances in MM therapy, many still die due to its high mortality rate. A study using computational simulations analyzed 100 natural ingredients from the SANC database to determine if they inhibited the IgH domain, a known cause of multiple myeloma. Natural component Diospyrin inhibited the IgH enzyme with the best binding energy of -10.3 kcal/mol and three carbon-hydrogen bonds, followed by Parviflorone F complex with a binding energy of -10.1 kcal/mol and two conventional-hydrogen bonds. As a result, the Molecular Dynamic simulation was used to test the stability of the two complexes. During the simulation, the Diospyrin molecule dissociated from the protein at roughly 67.5 ns, whereas the Parviflorone F molecule stayed attached to the protein throughout. The latter was the subject of the investigation. The analysis of the production run data revealed that the Parviflorone F molecule exhibits a variety of conformations within the binding pocket while keeping a relatively constant distance from the protein's center of mass. The analysis of the production run data revealed that the Parviflorone F molecule exhibited a variety of conformations within the binding pocket while keeping a relatively constant distance from the protein's center of mass. The root mean square deviation (RMSD) plots for both the protein and complex showed a stable and steady average value of 4.4 Å for the first 82 nanoseconds of manufacture. As a result, the average value increased to 8.3 Å. Furthermore, the components of the binding free energy, as computed by MM-GBSA, revealed that the mean binding energy of the Parviflorone F molecule was -23.88 kcal/mol. Finally, after analyzing all of the examination data, Parviflorone F was identified as a powerful inhibitor of the IgH domain and hence of the MM disease, which requires further in-vivo conformation.Communicated by Ramaswamy H. Sarma.

Temporal Tracking of Plasma Cells in vivo Using J-chain CreERT2 Reporter System

Plasma cells (PCs) are essential for humoral immunity, as they are responsible for the production of antibodies and contribute to immunological memory. Despite their importance, differentiating between long-lived and short-lived PCs in vivo remains a challenge due to a lack of specific markers to distinguish these populations. Addressing this gap, our study introduces a novel J-chain CreERT2 GFP allele (IgJCreERT2) for precise genetic studies of PCs. This model takes advantage of PC-restricted expression of the J-chain gene, enabling temporal and cell-specific tracking of PCs utilizing a tamoxifen-inducible Cre recombinase. Our in vitro and in vivo validation studies of the inducible Cre allele confirmed the fidelity and utility of this model and demonstrated the model's ability to trace the long-lived PC population in vivo following immunization. The IgJCreERT2 model allowed for detailed analysis of surface marker expression on PCs, revealing insights into PC heterogeneity and characteristics. Our findings not only validate the IgJCreERT2 mouse as a reliable tool for studying PCs but also facilitate the investigation of PC dynamics and longevity, particularly in the context of humoral immunity and vaccine responses. This model represents a significant advancement for the in-depth study of PCs in health and disease, offering a new avenue for the exploration of PC biology and immunological memory.

Biallelic NFATC1 mutations cause an inborn error of immunity with impaired CD8+ T-cell function and perturbed glycolysis

The nuclear factor of activated T cells (NFAT) family of transcription factors plays central roles in adaptive immunity in murine models; however, their contribution to human immune homeostasis remains poorly defined. In a multigenerational pedigree, we identified 3 patients who carry germ line biallelic missense variants in NFATC1, presenting with recurrent infections, hypogammaglobulinemia, and decreased antibody responses. The compound heterozygous NFATC1 variants identified in these patients caused decreased stability and reduced the binding of DNA and interacting proteins. We observed defects in early activation and proliferation of T and B cells from these patients, amenable to rescue upon genetic reconstitution. Stimulation induced early T-cell activation and proliferation responses were delayed but not lost, reaching that of healthy controls at day 7, indicative of an adaptive capacity of the cells. Assessment of the metabolic capacity of patient T cells revealed that NFATc1 dysfunction rendered T cells unable to engage in glycolysis after stimulation, although oxidative metabolic processes were intact. We hypothesized that NFATc1-mutant T cells could compensate for the energy deficit due to defective glycolysis by using enhanced lipid metabolism as an adaptation, leading to a delayed, but not lost, activation responses. Indeed, we observed increased 13C-labeled palmitate incorporation into citrate, indicating higher fatty acid oxidation, and we demonstrated that metformin and rosiglitazone improved patient T-cell effector functions. Collectively, enabled by our molecular dissection of the consequences of loss-of-function NFATC1 mutations and extending the role of NFATc1 in human immunity beyond receptor signaling, we provide evidence of metabolic plasticity in the context of impaired glycolysis observed in patient T cells, alleviating delayed effector responses.

Identification of the promoter region regulating the transcription of the REV7 gene

REV7 is involved in various biological processes including DNA repair and mutagenesis, cell cycle regulation, gene transcription, and carcinogenesis. REV7 is highly expressed in adult testicular germ cells as well as several malignant tumors. REV7 expression levels are associated with prognosis in several human cancers, however, the mechanism of REV7 transcriptional regulation has not been elucidated. In this study, we characterized the promoter region of the REV7 gene. A luciferase reporter assay using the human germ cell tumor cell line NEC8 was utilized to examine the upstream genomic region of REV7 for transcriptional activity, and two transcriptional activation regions were identified. We determined a small genomic region important for transcriptional activation using site-directed mutagenesis; this region is shared by several putative binding motifs for transcription factors, including the cAMP-responsive element modulator (CREM), cAMP-response element binding protein (CREB), and B-lymphocyte-induced maturation protein-1 (BLIMP-1). Exogenous CREM and CREB expression had no effect on the transcriptional activity in NEC8 cells or the human embryonic kidney cell line HEK293T. In contrast, exogenous BLIMP-1 expression increased luciferase reporter activity in HEK293T cells but unexpectedly decreased activity in NEC8 cells. Chromatin immunoprecipitation analysis demonstrated that BLIMP-1 binds to the genomic region near the binding motif in the REV7 promoter. Additionally, BLIMP-1 overexpression promoted endogenous REV7 expression in HEK293T cells. These findings suggest that BLIMP-1 may be a putative transcriptional regulator of REV7 in mammalian cells.

Exploring the putative role of PRDM1 and PRDM2 transcripts as mediators of T lymphocyte activation

BACKGROUND

T cell activation and programming from their naïve/resting state, characterized by widespread modifications in chromatin accessibility triggering extensive changes in transcriptional programs, is orchestrated by several cytokines and transcription regulators. PRDM1 and PRDM2 encode for proteins with PR/SET and zinc finger domains that control several biological processes, including cell differentiation, through epigenetic regulation of gene expression. Different transcripts leading to main protein isoforms with (PR +) or without (PR-) the PR/SET domain have been described. Although many studies have established the critical PRDM1 role in hematopoietic cell differentiation, maintenance and/or function, the single transcript contribution has not been investigated before. Otherwise, very few evidence is currently available on PRDM2. Here, we aimed to analyze the role of PRDM1 and PRDM2 different transcripts as mediators of T lymphocyte activation.

METHODS

We analyzed the transcription signature of the main variants from PRDM1 (BLIMP1a and BLIMP1b) and PRDM2 (RIZ1 and RIZ2) genes, in human T lymphocytes and Jurkat cells overexpressing PRDM2 cDNAs following activation through different signals.

RESULTS

T lymphocyte activation induced an early increase of RIZ2 and RIZ1 followed by BLIMP1b increase and finally by BLIMP1a increase. The "first" and the "second" signals shifted the balance towards the PR- forms for both genes. Interestingly, the PI3K signaling pathway modulated the RIZ1/RIZ2 ratio in favor of RIZ1 while the balance versus RIZ2 was promoted by MAPK pathway. Cytokines mediating different Jak/Stat signaling pathways (third signal) early modulated the expression of PRDM1 and PRDM2 and the relationship of their different transcripts confirming the early increase of the PR- transcripts. Different responses of T cell subpopulations were also observed. Jurkat cells showed that the acute transient RIZ2 increase promoted the balancing of PRDM1 forms towards BLIMP1b. The stable forced expression of RIZ1 or RIZ2 induced a significant variation in the expression of key transcription factors involved in T lymphocyte differentiation. The BLIMP1a/b balance shifted in favor of BLIMP1a in RIZ1-overexpressing cells and of BLIMP1b in RIZ2-overexpressing cells.

CONCLUSIONS

This study provides the first characterization of PRDM2 in T-lymphocyte activation/differentiation and novel insights on PRDM1 and PRDM2 transcription regulation during initial activation phases.

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

Epidemiological evidence supports an association between cow’s milk consumption and the risk of diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin lymphoma worldwide. This narrative review intends to elucidate the potential impact of milk-related agents, predominantly milk-derived exosomes (MDEs) and their microRNAs (miRs) in lymphomagenesis. Upregulation of PI3K-AKT-mTORC1 signaling is a common feature of DLBCL. Increased expression of B cell lymphoma 6 (BCL6) and suppression of B lymphocyte-induced maturation protein 1 (BLIMP1)/PR domain-containing protein 1 (PRDM1) are crucial pathological deviations in DLBCL. Translational evidence indicates that during the breastfeeding period, human MDE miRs support B cell proliferation via epigenetic upregulation of BCL6 (via miR-148a-3p-mediated suppression of DNA methyltransferase 1 (DNMT1) and miR-155-5p/miR-29b-5p-mediated suppression of activation-induced cytidine deaminase (AICDA) and suppression of BLIMP1 (via MDE let-7-5p/miR-125b-5p-targeting of PRDM1). After weaning with the physiological termination of MDE miR signaling, the infant’s BCL6 expression and B cell proliferation declines, whereas BLIMP1-mediated B cell maturation for adequate own antibody production rises. Because human and bovine MDE miRs share identical nucleotide sequences, the consumption of pasteurized cow’s milk in adults with the continued transfer of bioactive bovine MDE miRs may de-differentiate B cells back to the neonatal “proliferation-dominated” B cell phenotype maintaining an increased BLC6/BLIMP1 ratio. Persistent milk-induced epigenetic dysregulation of BCL6 and BLIMP1 expression may thus represent a novel driving mechanism in B cell lymphomagenesis. Bovine MDEs and their miR cargo have to be considered potential pathogens that should be removed from the human food chain.

scANANSE gene regulatory network and motif analysis of single-cell clusters

The recent development of single-cell techniques is essential to unravel complex biological systems. By measuring the transcriptome and the accessible genome on a single-cell level, cellular heterogeneity in a biological environment can be deciphered. Transcription factors act as key regulators activating and repressing downstream target genes, and together they constitute gene regulatory networks that govern cell morphology and identity. Dissecting these gene regulatory networks is crucial for understanding molecular mechanisms and disease, especially within highly complex biological systems. The gene regulatory network analysis software ANANSE and the motif enrichment software GimmeMotifs were both developed to analyse bulk datasets. We developed scANANSE, a software pipeline for gene regulatory network analysis and motif enrichment using single-cell RNA and ATAC datasets. The scANANSE pipeline can be run from either R or Python. First, it exports data from standard single-cell objects. Next, it automatically runs multiple comparisons of cell cluster data. Finally, it imports the results back to the single-cell object, where the result can be further visualised, integrated, and interpreted. Here, we demonstrate our scANANSE pipeline on a publicly available PBMC multi-omics dataset. It identifies well-known cell type-specific hematopoietic factors. Importantly, we also demonstrated that scANANSE combined with GimmeMotifs is able to predict transcription factors with both activating and repressing roles in gene regulation.

Disruption to the FOXO-PRDM1 axis resulting from deletions of chromosome 6 in acute lymphoblastic leukaemia

A common problem in the study of human malignancy is the elucidation of cancer driver mechanisms associated with recurrent deletion of regions containing multiple genes. Taking B-cell acute lymphoblastic leukaemia (B-ALL) and large deletions of 6q [del(6q)] as a model, we integrated analysis of functional cDNA clone tracking assays with patient genomic and transcriptomic data, to identify the transcription factors FOXO3 and PRDM1 as candidate tumour suppressor genes (TSG). Analysis of cell cycle and transcriptomic changes following overexpression of FOXO3 or PRDM1 indicated that they co-operate to promote cell cycle exit at the pre-B cell stage. FOXO1 abnormalities are absent in B-ALL, but like FOXO3, FOXO1 expression suppressed growth of TCF3::PBX1 and ETV6::RUNX1 B-ALL in-vitro. While both FOXOs induced PRDM1 and other genes contributing to late pre-B cell development, FOXO1 alone induced the key transcription factor, IRF4, and chemokine, CXCR4. CRISPR-Cas9 screening identified FOXO3 as a TSG, while FOXO1 emerged as essential for B-ALL growth. We relate this FOXO3-specific leukaemia-protective role to suppression of glycolysis based on integrated analysis of CRISPR-data and gene sets induced or suppressed by FOXO1 and FOXO3. Pan-FOXO agonist Selinexor induced the glycolysis inhibitor TXNIP and suppressed B-ALL growth at low dose (ID50 < 50 nM).

Progressive differentiation toward the long-lived plasma cell compartment in the bone marrow

The longevity of plasma cells is dependent on their ability to access and reside in so-called niches that are predominantly located in the bone marrow. Here, by employing a traceable method to label recently generated plasma cells, we showed that homeostatic plasma cells in the bone marrow and spleen were continuously replenished by newly generated B220hiMHC-IIhi populations that progressively differentiated into B220loMHC-IIlo long-lived plasma cell (LLPC) populations. We also found that, in the bone marrow, germinal center (GC)-independent and GC-dependent plasma cells decayed similarly upon NP-CGG engagement, and both entered the B220loMHC-IIlo LLPC pool. Compared with NP+B220hiMHC-IIhi plasma cells, NP+B220loMHC-IIlo cells were more immobilized in the bone marrow niches and showed better survival potential. Thus, our results suggest that the adhesion status of bone marrow plasma cells is dynamically altered during their differentiation and is associated with provision of survival signals.

Fundamentals to therapeutics: Epigenetic modulation of CD8+ T Cell exhaustion in the tumor microenvironment

In the setting of chronic antigen exposure in the tumor microenvironment (TME), cytotoxic CD8+ T cells (CTLs) lose their immune surveillance capabilities and ability to clear tumor cells as a result of their differentiation into terminally exhausted CD8+ T cells. Immune checkpoint blockade (ICB) therapies reinvigorate exhausted CD8+ T cells by targeting specific inhibitory receptors, thus promoting their cytolytic activity towards tumor cells. Despite exciting results with ICB therapies, many patients with solid tumors still fail to respond to such therapies and patients who initially respond can develop resistance. Recently, through new sequencing technologies such as the assay for transposase-accessible chromatin with sequencing (ATAC-seq), epigenetics has been appreciated as a contributing factor that enforces T cell differentiation toward exhaustion in the TME. Importantly, specific epigenetic alterations and epigenetic factors have been found to control CD8+ T cell exhaustion phenotypes. In this review, we will explain the background of T cell differentiation and various exhaustion states and discuss how epigenetics play an important role in these processes. Then we will outline specific epigenetic changes and certain epigenetic and transcription factors that are known to contribute to CD8+ T cell exhaustion. We will also discuss the most recent methodologies that are used to study and discover such epigenetic modulations. Finally, we will explain how epigenetic reprogramming is a promising approach that might facilitate the development of novel exhausted T cell-targeting immunotherapies.

Multi-target regulation of pro-inflammatory cytokine production by transcription factor Blimp-1

OBJECTIVE

Cytokine storm syndrome is a fatal condition related to infectious and autoimmune diseases. Here, we aim to investigate the regulatory mechanisms of Blimp-1 on multiple cytokine production.

METHODS

The Blimp1 shRNA was transfected into RAW264.7 macrophages, followed by Toll-like receptor (TLR) ligand stimulation. The mRNA and protein levels of cytokines were detected by real-time PCR and flow cytometric bead array. The nuclear translocation of AP-1 and NF-κB p65 was measured by immunofluorescence staining. The transcriptional activity was detected by luciferase reporter assay with 5 × NF-κB reporter or with IL6 promoter reporter.

RESULTS

Blimp-1 significantly inhibited the expression and secretion of IL-1β, IL-6, and IL-18 in macrophages during stimulation with a variety of TLR ligands. The immunofluorescence staining results showed that Blimp-1 strictly controlled the nuclear translocation of NF-κB p65 in LPS-challenged macrophages. Furthermore, Blimp-1 directly inhibited the transcriptional activity of NF-κB and the transcription of IL6 gene.

CONCLUSION

Blimp-1 represses the production of multiple pro-inflammatory cytokines by directly binding the genomic region and restricting the nuclear translocation and transcriptional activity of NF-κB. This finding may provide potential therapeutic strategies for the cytokine storm-related diseases.

The FES Gene at the 15q26 Coronary-Artery-Disease Locus Inhibits Atherosclerosis

BACKGROUND

Genome-wide association studies have discovered a link between genetic variants on human chromosome 15q26.1 and increased coronary artery disease (CAD) susceptibility; however, the underlying pathobiological mechanism is unclear. This genetic locus contains the FES (FES proto-oncogene, tyrosine kinase) gene encoding a cytoplasmic protein-tyrosine kinase involved in the regulation of cell behavior. We investigated the effect of the 15q26.1 variants on FES expression and whether FES plays a role in atherosclerosis.

METHODS AND RESULTS

Analyses of isogenic monocytic cell lines generated by CRISPR (clustered regularly interspaced short palindromic repeats)-mediated genome editing showed that monocytes with an engineered 15q26.1 CAD risk genotype had reduced FES expression. Small-interfering-RNA-mediated knockdown of FES promoted migration of monocytes and vascular smooth muscle cells. A phosphoproteomics analysis showed that FES knockdown altered phosphorylation of a number of proteins known to regulate cell migration. Single-cell RNA-sequencing revealed that in human atherosclerotic plaques, cells that expressed FES were predominately monocytes/macrophages, although several other cell types including smooth muscle cells also expressed FES. There was an association between the 15q26.1 CAD risk genotype and greater numbers of monocytes/macrophage in human atherosclerotic plaques. An animal model study demonstrated that Fes knockout increased atherosclerotic plaque size and within-plaque content of monocytes/macrophages and smooth muscle cells, in apolipoprotein E-deficient mice fed a high fat diet.

CONCLUSIONS

We provide substantial evidence that the CAD risk variants at the 15q26.1 locus reduce FES expression in monocytes and that FES depletion results in larger atherosclerotic plaques with more monocytes/macrophages and smooth muscle cells. This study is the first demonstration that FES plays a protective role against atherosclerosis and suggests that enhancing FES activity could be a potentially novel therapeutic approach for CAD intervention.

Aberrant DNA methylation in multiple myeloma: A major obstacle or an opportunity?

Drug resistance (DR) of cancer cells leading to relapse is a huge problem nowadays to achieve long-lasting cures for cancer patients. This also holds true for the incurable hematological malignancy multiple myeloma (MM), which is characterized by the accumulation of malignant plasma cells in the bone marrow (BM). Although new treatment approaches combining immunomodulatory drugs, corticosteroids, proteasome inhibitors, alkylating agents, and monoclonal antibodies have significantly improved median life expectancy, MM remains incurable due to the development of DR, with the underlying mechanisms remaining largely ill-defined. It is well-known that MM is a heterogeneous disease, encompassing both genetic and epigenetic aberrations. In normal circumstances, epigenetic modifications, including DNA methylation and posttranslational histone modifications, play an important role in proper chromatin structure and transcriptional regulation. However, in MM, numerous epigenetic defects or so-called ‘epimutations’ have been observed and this especially at the level of DNA methylation. These include genome-wide DNA hypomethylation, locus specific hypermethylation and somatic mutations, copy number variations and/or deregulated expression patterns in DNA methylation modifiers and regulators. The aberrant DNA methylation patterns lead to reduced gene expression of tumor suppressor genes, genomic instability, DR, disease progression, and high-risk disease. In addition, the frequency of somatic mutations in the DNA methylation modifiers seems increased in relapsed patients, again suggesting a role in DR and relapse. In this review, we discuss the recent advances in understanding the involvement of aberrant DNA methylation patterns and/or DNA methylation modifiers in MM development, progression, and relapse. In addition, we discuss their involvement in MM cell plasticity, driving myeloma cells to a cancer stem cell state characterized by a more immature and drug-resistant phenotype. Finally, we briefly touch upon the potential of DNA methyltransferase inhibitors to prevent relapse after treatment with the current standard of care agents and/or new, promising (immuno) therapies.

A Potential Prognostic Marker PRDM1 in Pancreatic Adenocarcinoma

Pancreatic adenocarcinoma (PAAD) is a major threat to people's health. PRDM1 is a transcription factor with multiple functions, and its functions have been validated in a variety of tumors; however, there are few studies reported on PRDM1 in PAAD. Using the GEPIA2 database, this research found that PRDM1 expression in PAAD was significantly higher than that in normal pancreatic tissue. The Kaplan-Meier Plotter database showed that high expression of PRDM1 in PAAD has a poor prognosis, suggesting that PRDM1 may be a potential prognostic marker in PAAD. The cBioPortal database shows that the expression of PRDM1 in PAAD is significantly correlated with its methylation degree. Further analysis on the coexpressed genes of PRDM1 in PAAD was performed by using LinkedOmics database to explore potential mechanisms. Based on gene enrichment analysis, PRDM1 was implicated in many pathways involved in tumor progression. In the construction of a PPI network of PRDM1 and its coexpressed gene protein via the STRING database, we found that PRDM1 may be involved in the pathogenesis and development of PAAD. TIMER database suggested that a high level of PRDM1 has a significant positive correlation with macrophages, neutrophils, and DCs. Potential methylation sites of PRDM1 were found through DNMIVD database, and MethSurv database explored eight sites which were significantly related with the prognosis of PAAD. In conclusion, PRDM1 may work as a prognostic marker or even provide a potential therapeutic strategy in PAAD.