Boosting of tau protein aggregation by CD40 and CD48 gene expression in Alzheimer's disease.

Neurodegenerative diseases result from the interplay of abnormal gene expression and various pathological factors. Therefore, a disease-specific integrative genetic approach is required to understand the complexities and causes of target diseases. Recent studies have identified the correlation between genes encoding several transmembrane proteins, such as the cluster of differentiation (CD) and Alzheimer's disease (AD) pathogenesis. In this study, CD48 and CD40 gene expression in AD, a neurodegenerative disease, was analyzed to infer this link. Total RNA sequencing was performed using an Alzheimer's disease mouse model brain and blood, and gene expression was determined using a genome-wide association study (GWAS). We observed a marked elevation of CD48 and CD40 genes in Alzheimer's disease. Indeed, the upregulation of both CD48 and CD40 genes was significantly increased in the severe Alzheimer's disease group. With the elevation of CD48 and CD40 genes in Alzheimer's disease, associations of protein levels were also markedly increased in tissues. In addition, overexpression of CD48 and CD40 genes triggered tau aggregation, and co-expression of these genes accelerated aggregation. The nuclear factor kappa B (NF-ĸB) signaling pathway was enriched by CD48 and CD40 gene expression: it was also associated with tau pathology. Our data suggested that the CD48 and CD40 genes are novel AD-related genes, and this approach may be useful as a diagnostic or therapeutic target for the disease.

Genome-wide CRISPR screens identify CD48 defining susceptibility to NK cytotoxicity in peripheral T-cell lymphomas.

Adult T-cell leukemia/lymphoma (ATLL) is one of the aggressive peripheral T-cell neoplasms with a poor prognosis. Accumulating evidence demonstrates that escape from adaptive immunity is a hallmark of ATLL pathogenesis. However, the mechanisms by which ATLL cells evade natural killer (NK)-cell-mediated immunity have been poorly understood. Here we show that CD48 expression in ATLL cells determines the sensitivity for NK-cell-mediated cytotoxicity against ATLL cells. We performed unbiased genome-wide clustered regularly interspaced short palindromic repeat (CRISPR) screening using 2 ATLL-derived cell lines and discovered CD48 as one of the best-enriched genes whose knockout conferred resistance to YT1-NK cell line-mediated cytotoxicity. The ability of CD48-knockout ATLL cells to evade NK-cell effector function was confirmed using human primary NK cells with reduced interferon-γ (IFNγ) induction and degranulation. We found that primary ATLL cells had reduced CD48 expression along with disease progression. Furthermore, other subgroups among aggressive peripheral T-cell lymphomas (PTCLs) also expressed lower concentrations of CD48 than normal T cells, suggesting that CD48 is a key molecule in malignant T-cell evasion of NK-cell surveillance. Thus, this study demonstrates that CD48 expression is likely critical for malignant T-cell lymphoma cell regulation of NK-cell-mediated immunity and provides a rationale for future evaluation of CD48 as a molecular biomarker in NK-cell-associated immunotherapies.

Hypersensitivity response has negligible impact on Hematopoietic Stem Cells.

Immune cells are generated from hematopoietic stem cells (HSCs) in the bone marrow (BM). Immune stimulation can rapidly activate HSCs out of their quiescent state to accelerate the generation of immune cells. HSCs' activation follows various viral or bacterial stimuli, and we sought to investigate the hypersensitivity immune response. Surprisingly, the Ova-induced hypersensitivity peritonitis model finds no significant changes in BM HSCs. HSC markers cKIT, SCA1, CD48, CD150, and the Fgd5-mCherry reporter showed no significant difference from control. Functionally, hypersensitivity did not alter HSCs' potency, as assayed by transplantation. We further characterized the possible impact of hypersensitivity using RNA-sequencing of HSCs, finding minor changes at the transcriptome level. Moreover, hypersensitivity induced no significant change in the proliferative state of HSCs. Therefore, this study suggests that, in contrast to other immune stimuli, hypersensitivity has no impact on HSCs.

Immunogenicity and structural efficacy of P41 of Plasmodium sp. as potential cross-species blood-stage malaria vaccine.

Vaccine based strategies offer a promising future in malaria control by generating protective immunity against natural infection. However, vaccine development is hindered by the Plasmodium sp. genetic diversity. Previously, we have shown P41 protein from 6-Cysteine shared by Plasmodium sp. and could be used for cross-species anti-malaria vaccines. Two different approaches, ancestral, and consensus sequence, could produce a single target for all human-infecting Plasmodium. In this study, we investigated the efficacy of ancestral and consensus of P41 protein. Phylogenetic and time tree reconstruction was conducted by RAXML and BEAST2 package to determine the relationship of known P41 sequences. Ancestral and consensus sequences were reconstructed by the GRASP server and Unipro Ugene software, respectively. The structural prediction was made using the Psipred and Rosetta program. The protein characteristic was analyzed by assessing hydrophobicity and Post-Translational Modification sites. Meanwhile, the immunogenicity score for B-cell, T-cell, and MHC was determined using an immunoinformatic approach. The result suggests that ancestral and consensus have a distinct protein characteristic with high immunogenicity scores for all immune cells. We found one shared conserved epitope with phosphorylation modification from the ancestral sequence to target the cross-species vaccine. Thus, this study provides detailed insight into P41 efficacy for the cross-species anti-malaria blood-stage vaccine.

FOXP3 protects conventional human T cells from premature restimulation-induced cell death.

The adaptive immune response relies on specific apoptotic programs to maintain homeostasis. Conventional effector T cell (Tcon) expansion is constrained by both forkhead box P3 (FOXP3)+-regulatory T cells (Tregs) and restimulation-induced cell death (RICD), a propriocidal apoptosis pathway triggered by repeated stimulation through the T-cell receptor (TCR). Constitutive FOXP3 expression protects Tregs from RICD by suppressing SLAM-associated protein (SAP), a key adaptor protein that amplifies TCR signaling strength. The role of transient FOXP3 induction in activated human CD4 and CD8 Tcons remains unresolved, but its expression is inversely correlated with acquired RICD sensitivity. Here, we describe a novel role for FOXP3 in protecting human Tcons from premature RICD during expansion. Unlike FOXP3-mediated protection from RICD in Tregs, FOXP3 protects Tcons through a distinct mechanism requiring de novo transcription that does not require SAP suppression. Transcriptome profiling and functional analyses of expanding Tcons revealed that FOXP3 enhances expression of the SLAM family receptor CD48, which in turn sustains basal autophagy and suppresses pro-apoptotic p53 signaling. Both CD48 and FOXP3 expression reduced p53 accumulation upon TCR restimulation. Furthermore, silencing FOXP3 expression or blocking CD48 decreased the mitochondrial membrane potential in expanding Tcons with a concomitant reduction in basal autophagy. Our findings suggest that FOXP3 governs a distinct transcriptional program in early-stage effector Tcons that maintains RICD resistance via CD48-dependent protective autophagy and p53 suppression.

Divergent Traits and Ligand-Binding Properties of the Cytomegalovirus CD48 Gene Family.

The genesis of gene families by the capture of host genes and their subsequent duplication is a crucial process in the evolution of large DNA viruses. CD48 is a cell surface molecule that interacts via its N-terminal immunoglobulin (Ig) domain with the cell surface receptor 2B4 (CD244), regulating leukocyte cytotoxicity. We previously reported the presence of five CD48 homologs (vCD48s) in two related cytomegaloviruses, and demonstrated that one of them, A43, binds 2B4 and acts as a soluble CD48 decoy receptor impairing NK cell function. Here, we have characterized the rest of these vCD48s. We show that they are highly glycosylated proteins that display remarkably distinct features: divergent biochemical properties, cellular locations, and temporal expression kinetics. In contrast to A43, none of them interacts with 2B4. Consistent with this, molecular modeling of the N-terminal Ig domains of these vCD48s evidences notable changes as compared to CD48, suggesting that they interact with alternative targets. Accordingly, we demonstrate that one of them, S30, tightly binds CD2, a crucial T- and NK-cell adhesion and costimulatory molecule. Thus, our findings show how a key host immune receptor gene captured by a virus can be subsequently remodeled to evolve new immunoevasins with altered binding properties.

Alteration of liver immunity by increasing inflammatory response during co-administration of methamphetamine and atazanavir.

Objective: Use of methamphetamine (METH) is prevalent among HIV-infected individuals. Previous research has shown that both METH and HIV protease inhibitors exert influences on mitochondrial respiratory metabolism and hepatic nervous system. This study aims to study the joint effect of METH and HIV protease inhibitors on hepatic immune function.Materials and methods: Based on the differentially expressed genes obtained from RNA-seq of the liver from mouse model, the expression levels of CD48 and Macrophage Receptor with Collagenous Structure (MARCO) were examined using qRT-PCR and flow cytometry, and the expression and secretion of cytokines IL-1ß, IL-6, IL-8, IL-10, IFN-γ, IFN-ß, and TNF-α were determined using qRT-PCR and ELISA in THP-1-derived macrophages.Results: Our results indicated that compared with the control group, CD48 molecules were significantly down-regulated by METH-atazanavir co-treatment, and the expression level of CD48 decreased as METH concentration increases. MARCO molecules were increased, especially at larger doses of METH and atazanavir treatment. In addition, in the presence of METH-atazanavir, the expression and secretion of a series of pro-inflammatory cytokines TNF-α, IL-1ß, IL-6, and IL-8 increased while the expression and secretion of anti-inflammatory cytokine IL-10 decreased.Conclusion: These results demonstrated that METH and atazanavir had a combined impact on the liver immunity, suggesting that the co-treatment could enhance inflammatory response and suppress NK cell activation via CD48.

Acute myeloid leukemia immune escape by epigenetic CD48 silencing.

Acute myeloid leukemia (AML) is a malignant disorder of hemopoietic stem cells. AML can escape immunosurveillance of natural killer (NK) by gene mutation, fusions and epigenetic modification. The mechanism of AML immune evasion is not clearly understood. Here we show that CD48 high expression is a favorable prognosis factor that is down-regulated in AML patients, which can help AML evade from NK cell recognition and killing. Furthermore, we demonstrate that CD48 expression is regulated by methylation and that a hypomethylating agent can increase the CD48 expression, which increases the NK cells killing in vitro. Finally, we show that CD48 high expression can reverse the AML immune evasion and activate NK cells function in vivo. The present study suggests that a combination the hypomethylating agent and NK cell infusion could be a new strategy to cure AML.

Development of a gp60-subtyping method for Cryptosporidium felis.

BACKGROUND: Feline cryptosporidiosis is an increasing problem, especially in catteries. In humans, close contact with cats could be a potential source of infection although the risk of contracting cryptosporidiosis caused by Cryptosporidium felis is considered to be relatively low. Sequencing of the 60-kDa glycoprotein gene is a commonly used tool for investigation of the genetic diversity and transmission dynamics of Cryptosporidium species. However, until now the sequence of gp60 from C. felis has not been available and genotyping has been limited to less discriminatory markers, such as 18S rRNA, COWP and HSP70. METHODS: We have identified the gp60 orthologue within the genome sequence of C. felis, and used the sequence to design a nested PCR for subtyping purposes. A total of 128 clinical isolates of both feline and human origin, were used to evaluate the marker. RESULTS: Sequence analysis revealed large variations between the different samples. The C. felis gp60 lack the characteristic serine-tract found in many other cryptosporidian orthologues, instead it has an insertion of variable length (361-742 nt). Also, two cases of suspected zoonotic transmission of C. felis between cats and humans were successfully confirmed. CONCLUSIONS: We have identified the gp60 gene in C. felis and show how this highly variable marker can be used in epidemiological investigations.

Molecular characterization and expression of CD48 in Nile tilapia (Oreochromis niloticus) in response to different stimulus.

CD48 is a glycosylphosphatidylinositol-anchored protein involved in lymphocyte adhesion, activation, and costimulation. In this study, the CD48 gene of tilapia (Oreochromis niloticus, named On-CD48), was cloned from the head kidney of tilapia. The coding sequences is 654 bp and encoding 217 amino acids. The deduced amino acid sequence of On-CD48 with an estimated molecular weight of 24.4 kDa and a theoretical pI of 5.03. Amino acid alignment indicated that it had two immunoglobulin-like domain conserved region. In healthy tilapia, the On-CD48 could be detected in all the examined tissues and the highest expression level in the spleen. The expression of On-CD48 in the spleen and head kidney was decreased after immunized by formalin-inactivated Streptococcus agalactiae, and the peak was observed in the spleen at 24 h and appeared again at 96 h, and in the head kidney gradual decline before 48 h then gradually increased to the original level. qPCR analysis of inactivated S. agalactiae, LPS and Poly I:C stimulated at the whole lymphocyte level showed that the stimulation of the Poly I:C was more sensitive. Prokaryotic expression results showed that efficient expression of On-CD48 protein could be realized after induced with 0.5 mmol L-1 IPTG in E. coli BL21 (DE3) for 10 h at 18 °C. The result of subcellular localization showed that On-CD48 were evenly distributed in the whole cell of HEK-293T. Western Blot confirmed that the molecular weight of the recombinant On-CD48 was about 21 kDa, consistent with the predicted result. The results of this study will lay a strong foundation for the further study of On-CD48 molecular function in tilapia.

TGF-ß regulated leukemia cell susceptibility against NK targeting through the down-regulation of the CD48 expression.

Transforming growth factor-ß (TGF-ß) is known to function as a dual role regulatory cytokine for being either a suppresser or promoter during tumor initiation and progression. In solid tumors, TGF-ß secreted from tumor microenvironment acts as a suppresser against host immunity, like natural killer (NK) cells, to favor tumor evasion. However, besides solid tumors, the underlying mechanism of how TGF-ß regulates leukemogenesis, tumor progression, immunoediting, and NK function is still not clear in detail. In this study, we found that TGF-ß induced leukemia MEG-01 and U937 cells to become less sensitive to NK-92MI targeting by down-regulating CD48, a ligand for NK activating receptor 2B4, but not down-regulating other tumor-associated carbohydrate antigens (TACAs). In CD48-knockdown cells, cells responding to NK-92MI targeting displayed a phenotype of less NK susceptibility and cell conjugation. On the other hand, when NK cells were treated with TGF-ß, TGF-ß suppressed NK recognition, degranulation, and killing activity in time-dependent manner by regulating ICAM-1 binding capacity instead of affecting expressions of activating and inhibitory receptors. Taken together, both leukemia cells and immune NK cells could be regulated by TGF-ß through suppressing leukemia cell surface CD48 to escape from host surveillance and down-regulating NK cell surface ICAM-1 binding activity to impair NK functions, respectively. Our results suggested that TGF-ß had effect in leukemia similar to that observed in solid tumors but through different regulatory mechanism.

Identification of human endogenous retrovirus transcripts in Hodgkin Lymphoma cells.

During the last decades, the prognosis for patients with Hodgkin Lymphoma (HL) has been steadily improved. Nevertheless, new and less toxic therapy strategies have to be developed especially for patients with advanced disease. The activation of human endogenous retroviruses (HERV) is suspected to occur in HL and therefore, HERV might represent interesting target structures. In order to identify transcribed HERV of the HERV-H and HERV-K families in HL we used a reverse transcription-polymerase chain reaction based cloning approach. In addition to unspliced HERV-H and HERV-K transcripts, we detected spliced HERV-K transcripts that matched genomic sequences with the expected splicing-donor and splicing-acceptor sites. Of particular interest was the expression of HERV-K18 related transcripts at the CD48 locus. Our data indicate transcriptional activity of several HERV loci in HL cells.

Multi-omics analysis identifies pathways and genes involved in diffuse-type gastric carcinogenesis induced by E-cadherin, p53, and Smad4 loss in mice.

The molecular mechanisms underlying the pathogenesis of diffuse-type gastric cancer (DGC) have not been adequately explored due to a scarcity of appropriate animal models. A recently developed tool well suited for this line of investigation is the Pdx-1-Cre;Cdh1F/+ ;Trp53F/F ;Smad4F/F (pChe PS) mouse model that spontaneously develops metastatic DGC showing nearly complete E-cadherin loss. Here, we performed a proteogenomic analysis to uncover the molecular changes induced by the concurrent targeting of E-cadherin, p53, and Smad4 loss. The gene expression profiles of mouse DGCs and in vivo gastric phenotypes from various combinations of gene knockout demonstrated that these mutations collaborate to activate cancer-associated pathways to generate aggressive DGC. Of note, WNT-mediated epithelial-to-mesenchymal transition (EMT) and extracellular matrix (ECM)-cytokine receptor interactions were prominently featured. In particular, the WNT target gene osteopontin (OPN) that functions as an ECM cytokine is highly upregulated. In validation experiments, OPN contributed to DGC stemness by promoting cancer stem cell (CSC) survival and chemoresistance. It was further found that Bcl-xL acts as a targetable downstream effector of OPN in DGC CSC survival. In addition, Zeb2 and thymosin-ß4 (Tß4) were identified as prime candidates as suppressors of E-cadherin expression from the remaining Cdh1 allele during DGC development. Specifically, Tß4 suppressed E-cadherin expression and anoikis while promoting cancer cell growth and migration. Collectively, these proteogenomic analyses broaden and deepen our understanding of the contribution of key driver mutations in the stepwise carcinogenesis of DGC through novel effectors, namely OPN and Tß4.

A Novel CD48-Based Analysis of Sepsis-Induced Mouse Myeloid-Derived Suppressor Cell Compartments.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous subset of cells that expands dramatically in many disease states and can suppress T-cell responses. MDSCs mainly include monocytic and granulocytic subpopulations that can be distinguished in mice by the expression of Ly6G and Ly6C cell surface markers. This identification system has been validated in experimental tumor models, but not in models of inflammation-associated conditions such as sepsis. We challenged growth factor independent 1 transcription repressor green fluorescent protein (Gfi1:GFP) knock-in reporter mice with cecal ligation and puncture surgery and found that CD11b+Ly6GlowLy6Chigh MDSCs in this sepsis model comprised both monocytic and granulocytic MDSCs. The evidence that conventional Ly6G/Ly6C marker analysis may not be suited to study of inflammation-induced MDSCs led to the development of a novel strategy of distinguishing granulocytic MDSCs from monocytic MDSCs in septic mice by expression of CD48. Application of this novel model should help achieve a more accurate understanding of the inflammation-induced MDSC activity.

Anti-CD48 Monoclonal Antibody Attenuates Experimental Autoimmune Encephalomyelitis by Limiting the Number of Pathogenic CD4+ T Cells.

CD48 (SLAMF2) is an adhesion and costimulatory molecule constitutively expressed on hematopoietic cells. Polymorphisms in CD48 have been linked to susceptibility to multiple sclerosis (MS), and altered expression of the structurally related protein CD58 (LFA-3) is associated with disease remission in MS. We examined CD48 expression and function in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. We found that a subpopulation of CD4+ T cells highly upregulated CD48 expression during EAE and were enriched for pathogenic CD4+ T cells. These CD48++CD4+ T cells were predominantly CD44+ and Ki67+, included producers of IL-17A, GM-CSF, and IFN-γ, and were most of the CD4+ T cells in the CNS. Administration of anti-CD48 mAb during EAE attenuated clinical disease, limited accumulation of lymphocytes in the CNS, and reduced the number of pathogenic cytokine-secreting CD4+ T cells in the spleen at early time points. These therapeutic effects required CD48 expression on CD4+ T cells but not on APCs. Additionally, the effects of anti-CD48 were partially dependent on FcγRs, as anti-CD48 did not ameliorate EAE or reduce the number of cytokine-producing effector CD4+ T cells in Fcεr1γ-/- mice or in wild-type mice receiving anti-CD16/CD32 mAb. Our data suggest that anti-CD48 mAb exerts its therapeutic effects by both limiting CD4+ T cell proliferation and preferentially eliminating pathogenic CD48++CD4+ T cells during EAE. Our findings indicate that high CD48 expression is a feature of pathogenic CD4+ T cells during EAE and point to CD48 as a potential target for immunotherapy.

sCD48 is anti-inflammatory in Staphylococcus aureus Enterotoxin B-induced eosinophilic inflammation.

BACKGROUND: Staphylococcus aureus, one of the most important pathogens, is heavily associated with allergy. S. aureus and its toxins interact with eosinophils through CD48, a GPI-anchored receptor important in allergy mainly as expressed by the eosinophils (mCD48). CD48 can exist in a soluble form (sCD48). Our aim was to investigate SEB-induced regulation of eosinophil CD48 and the possible formation and role of sCD48 in SEB-mediated eosinophil activation in vitro and in vivo. METHODS: Human peripheral blood eosinophils were activated by SEB with or without inhibitors for phospholipases (PL) (-C or -D), or cycloheximide, or brefeldin A. We evaluated eosinophil activation (CD11b expression or EPO/IL-8 release), mCD48 (flow cytometry), sCD48 (ELISA), SEB binding to sCD48 (ELISA), and chemotaxis toward SEB. C57BL/6 mice were pre-injected (ip.) with sCD48, and then, peritonitis was induced by SEB injection; peritoneal lavages were collected after 48 h and analyzed by flow cytometry and ELISA. RESULTS: SEB-activated human eosinophils formed sCD48, directly correlating with CD11b expression, through cell-associated PL-C and -D. mCD48 remained stable due to up-regulation in CD48 transcription and cellular trafficking. sCD48 bound to SEB and down-regulated SEB stimulatory effects on eosinophils as assessed by EPO and IL-8 release and eosinophil chemotaxis toward SEB. sCD48 showed anti-inflammatory activity in a SEB-induced mouse peritonitis model. CONCLUSIONS: SEB regulates CD48 dynamics on eosinophils. Our data indicate sCD48 as a SEB-induced 'decoy' receptor derived from eosinophil and therefore as a potential anti-inflammatory tool in S. aureus-induced eosinophil inflammation often associated with allergy.