Cell adhesion and polarity during immune interactions

Genome-wide survey reveals the genetic background of Xinjiang Brown cattle in China

Introduction: Xinjiang Brown cattle are a famous dual-purpose (dairy-beef) cultivated breed in China that occupy a pivotal position within the cattle breeding industry in Xinjiang, China. However, little information is available on the genetic background of this breed. To fill this research gap, we conducted a whole-genome screen using specific-locus amplified fragment sequencing to examine the genetic structure and diversity of 130 Xinjiang Brown cattle-grazing type (XBG, traditional type) cattle. Methods: A subsequent joint analysis incorporating two ancestral breeds, specifically 19 Brown Swiss (BS) foreign and nine Kazakh (KZ) Chinese cattle, as well as 20 Xinjiang Brown cattle-housing type (XBH) cattle, was used to explore the genetic background of the Xinjiang Brown cattle. Results: The results showed that, after nearly a century of crossbreeding, XBG cattle formed a single population with a stable genetic performance. The genetic structure, genetic diversity, and selection signature analysis of the two ancestral types showed highly different results compared to that of XBH cattle. Local ancestry inference showed that the average proportions of XGB cattle within the BS and KZ cattle lineages were 37.22% and 62.78%, respectively, whereas the average proportions of XBH cattle within the BS and KZ cattle lineages were 95.14% and 4.86%, respectively. Thus, XGB cattle are more representative of all Xinjiang Brown cattle, in line with their breeding history, which involves crossbreeding. Two complementary approaches, fixation index and mean nucleotide diversity, were used to detect selection signals in the four aforementioned cattle breeds. Finally, the analysis of 26 candidate genes in Xinjiang Brown cattle revealed significant enrichment in 19 Gene Ontology terms, and seven candidate genes were enriched in three pathways related to disease resistance (CDH4, SIRPB1, and SIRPα) and the endocrine system (ADCY5, ABCC8, KCNJ11, and KCNMA1). Finally, development of the core SNPs in XBG cattle yielded 8,379 loci. Conclusion: The results of this study detail the evolutionary process of crossbreeding in Xinjiang Brown cattle and provide guidance for selecting and breeding new strains of this species.

ICAM-1 mediated cell-cell adhesion exerts dual roles on human B cell differentiation and IgG production

Intercellular adhesion molecule 1 (ICAM-1) plays prominent roles in mediating cell-cell adhesion which also facilitates B cell activation and differentiation with the help from CD4+ T cells. Here, we have reported a unique phenomenon that increased ICAM-1 on purified human CD4+ T cells upon anti-CD3/CD28 stimulation enhanced CD4+ T-B cell adhesion whereas induced less B cell differentiation and IgG production. This was largely due to increased PD-1 expression on CD19hi B cells after coculturing with hyperactivated CD4+ T cells. Consequently, ICAM-1 blockade during CD4+ T cell-B cell coculture promoted IgG production with the activation of ERK1/2 and Blimp-1/IRF4 upregulation. Consistently, CD4+ T cells from moderate-to-severe SLE patients with high ICAM-1 expression mediated less IgG production after T-B coculture. Therefore, ICAM-1-mediated human CD4+ T-B cell adhesion provides dual roles on B cell differentiation and IgG production partially depending on expression levels of PD-1 on B cells, supporting cell adhesion and subsequent PD-1 induction as an alternative intrinsic checkpoint for B cell differentiation.

Focal adhesion signaling pathway involved in skin immune response of tongue sole Cynoglossus semilaevis to Vibrio vulnificus infection

Focal adhesion (FA) plays a key role in cell adhesion, migration and antibacterial immune, but it remained unclear in fish. In this study, half-smooth tongue sole Cynoglossus semilaevis were infected with Vibrio vulnificus, and then immune-related protein in the skin, especially for FA signaling pathway were screened and identified by iTRAQ analysis. Results showed that the differentially expressed proteins (DEPs) in skin immune response (eg., ITGA6, FN, COCH, AMBP, COL6A1, COL6A3, COL6A6, LAMB1, LAMC1, FLMNA) were firstly found in FA signaling pathway. Furthermore, the validation analysis of FA-related genes were basically consistent with the iTRAQ data at 36 hpi (r = 0.678, p < 0.01), and their spatio-temporal expressions were confirmed by qPCR analysis. The molecular characterization of vinculin of C. semilaevis was described. This study will provide a new perspective for understanding the molecular mechanism of FA signaling pathway in the skin immune response in marine fish.

Single cell multi-omic reference atlases of non-human primate immune tissues reveals CD102 as a biomarker for long-lived plasma cells

In response to infection or immunization, antibodies are produced that provide protection against re-exposure with the same pathogen. These antibodies can persist at high titers for decades and are maintained by bone marrow-resident long-lived plasma cells (LLPC). However, the durability of antibody responses to immunization varies amongst vaccines. It is unknown what factors contribute to the differential longevity of serum antibody responses and whether heterogeneity in LLPC contributes to this phenomenon. While LLPC differentiation has been studied extensively in mice, little is known about this population in humans or non-human primates (NHP). Here, we use multi-omic single-cell profiling to identify and characterize the LLPC compartment in NHP. We identify LLPC biomarkers including the marker CD102 and show that CD102 in combination with CD31 identifies LLPC in NHP bone marrow. Additionally, we find that CD102 is expressed by LLPC in mouse and humans. These results further our understanding of the LLPC compartment in NHP, identify biomarkers of LLPC, and provide tissue-specific single cell references for future studies.

Gene Set Enrichment Analysis Detected Immune Cell-Related Pathways Associated with Primary Sclerosing Cholangitis

Aim

To explore various immune cell-related causal pathways for primary sclerosing cholangitis (PSC).

Methods

Immune cell-related pathway association study was conducted via integrative analysis of PSC GWAS summary and five immune cell-related eQTL datasets. The GWAS summary data of PSC was driven from 4,796 PSC cases and 19,955 healthy controls. The eQTL datasets of CD4+ T cells, CD8+ T cells, B cells, natural killer cells (NK), monocytes, and peripheral blood cells (PB) were collected from recently eQTL study. The PSC GWAS summary dataset was first aligned with eQTL datasets of six blood cells to obtain the GWAS summary data at overlapped eQTL loci, separately. For each type of cell, the obtained PSC GWAS summary dataset of eQTLs was subjected to pathway enrichment analysis. 853 biological pathways from Kyoto Encyclopedia of Genes and Genomes, BioCarta, and Reactome pathway databases were analyzed.

Results

We identified 36 pathways for B cells, 33 pathways for CD4+ T cells, 28 pathways for CD8+ T cells, 33 pathways for monocytes (MN), 35 pathways for NK cells, and 33 for PB cells (all empirical P values <5.0 × 10-5). Comparing the pathway analysis results detected 25 pathways shared by five immune cells, such as KEGG_CELL_ADHESION_MOLECULES_CAMS (P value <5.0 × 10-5) and REACTOME_MHC_CLASS_II_ANTIGEN_ PRESENTATION (P value <5.0 × 10-5). Several cell-specific pathways were also identified, including BIOCARTA_INFLAM_PATHWAY (P value <5 × 10-5) for B cell.

Conclusion

Our study holds potential to identify novel candidate causal pathways and provides clues for revealing the complex genetic mechanism of PSC.

CD28 and chemokine receptors: Signalling amplifiers at the immunological synapse

T cells are master regulators of the immune response tuning, among others, B cells, macrophages and NK cells. To exert their functions requiring high sensibility and specificity, T cells need to integrate different stimuli from the surrounding microenvironment. A finely tuned signalling compartmentalization orchestrated in dynamic platforms is an essential requirement for the proper and efficient response of these cells to distinct triggers. During years, several studies have depicted the pivotal role of the cytoskeleton and lipid microdomains in controlling signalling compartmentalization during T cell activation and functions. Here, we discuss mechanisms responsible for signalling amplification and compartmentalization in T cell activation, focusing on the role of CD28, chemokine receptors and the actin cytoskeleton. We also take into account the detrimental effect of mutations carried by distinct signalling proteins giving rise to syndromes characterized by defects in T cell functionality.

Combined assessment of S- and N-specific IL-2 and IL-13 secretion and CD69 neo-expression for discrimination of post-infection and post-vaccination cellular SARS-CoV-2-specific immune response

BACKGROUND

Antibody-based tests are available for measuring SARS-CoV-2-specific immune responses but fast T-cell assays remain scarce. Robust T cell-based tests are needed to differentiate specific cellular immune responses after infection from those after vaccination.

METHODS

One hundred seventeen individuals (COVID-19 convalescent patients: n = 40; SARS-CoV-2 vaccinees: n = 41; healthy controls: n = 36) were evaluated for SARS-CoV-2-specific cellular immune responses (proliferation, Th1, Th2, Th17, and inflammatory cytokines, activation-induced marker [AIM] expression) by incubating purified peripheral blood mononuclear cells (PBMC) or whole blood (WB) with SARS-CoV-2 peptides (S, N, or M), vaccine antigens (tetanus toxoid, tick borne encephalitis virus) or polyclonal stimuli (Staphylococcal enterotoxin, phytohemagglutinin).

RESULTS

N-peptide mix stimulation of WB identified the combination of IL-2 and IL-13 secretion as superior to IFN-γ secretion to discriminate between COVID-19-convalescent patients and healthy controls (p < .0001). Comparable results were obtained with M- or S-peptides, the latter almost comparably recalled IL-2, IFN-γ, and IL-13 responses in WB of vaccinees. Analysis 10 months as opposed to 10 weeks after COVID-19, but not allergic disease status, positively correlated with IL-13 recall responses. WB cytokine responses correlated with cytokine and proliferation responses of PBMC. Antigen-induced neo-expression of the C-type lectin CD69 on CD4⁺ (p < .0001) and CD8⁺ (p = .0002) T cells informed best about the SARS-CoV-2 exposure status with additional benefit coming from CD25 upregulation.

CONCLUSION

Along with N- and S-peptide-induced IL-2 and CD69 neo-expression, we suggest to include the type 2 cytokine IL-13 as T-cellular recall marker for SARS-CoV-2 specific T-cellular immune responses after infection and vaccination.

Mouse Liver B Cells Phagocytose Streptococcus pneumoniae and Initiate Immune Responses against Their Antigens

Recent studies have revealed that mammalian B cells ingest particulate Ags, such as bacteria, although little is known about the effect of this function on acquired immunity. We investigated the role of bacterium-phagocytosing B cells in acquired host immune responses. Cultured mouse liver B cells substantially phagocytosed serum-opsonized Streptococcus pneumoniae and produced IgM. On adoptive transfer of liver B cells that phagocytose S. pneumoniae labeled with pHrodo Red succinimidyl ester, recipient mice showed elevated plasma levels of IgG specific for bacterial Ags. In particular, the levels of IgG2a and IgG2b specific for pneumococcal surface protein A, as well as IgG3 for pneumococcal polysaccharide, were markedly increased compared with total IgG specific for each Ag. When phagocytic liver B cells were cultured with spleen CD4⁺ T cells obtained from mice primed with heat-killed S. pneumoniae 7 d before, they induced IL-2 production and proliferation of the CD4⁺ T cells, along with Th1 cytokine production. However, they induced neither the CD4⁺ T cell production of IL-21, a suggested marker promoting B cell proliferation and differentiation, nor the expression of genes important for somatic hypermutation or isotype switching; such responses were particularly evident when splenic B cells merely capturing S. pneumoniae without processing them were cultured with spleen CD4⁺ T cells. These findings suggest that phagocytic liver B cells may be involved in acquired immune responses by presenting derivative peptides to CD4⁺ T cells without their own somatic hypermutation or isotype switching.

Synapse topology and downmodulation events determine the functional outcome of anti-CD19 T cell-redirecting strategies

Cancer immunotherapy strategies based on the endogenous secretion of T cell-redirecting bispecific antibodies by engineered T lymphocytes (STAb-T) are emerging as alternative or complementary approaches to those based on chimeric antigen receptors (CAR-T). The antitumor efficacy of bispecific anti-CD19 × anti-CD3 (CD19×CD3) T cell engager (BiTE)-secreting STAb-T cells has been demonstrated in several mouse models of B-cell acute leukemia. Here, we have investigated the spatial topology and downstream signaling of the artificial immunological synapses (IS) that are formed by CAR-T or STAb-T cells. Upon interaction with CD19-positive target cells, STAb-T cells form IS with structure and signal transduction, which more closely resemble those of physiological cognate IS, compared to IS formed by CAR-T cells expressing a second-generation CAR bearing the same CD19-single-chain variable fragment. Importantly, while CD3 is maintained at detectable levels on the surface of STAb-T cells, indicating sustained activation mediated by the secreted BiTE, the anti-CD19 CAR was rapidly downmodulated, which correlated with a more transient downstream signaling. Furthermore, CAR-T cells, but not STAb-T cells, provoke an acute loss of CD19 in target cells. Such differences might represent advantages of the STAb-T strategy over the CAR-T approach and should be carefully considered in order to develop more effective and safer treatments for hematological malignancies.

Molecular Identification of Nocardia seriolae and Comparative Analysis of Spleen Transcriptomes of Hybrid Snakehead (Channa maculata Female × Channa argus Male) With Nocardiosis Disease

Hybrid snakehead (Channa maculata female × Channa argus male) is a new freshwater aquaculture fish species in southern China. During intensive aquaculture, hybrid snakeheads are often infected by Nocardia seriolae. In this study, hybrid snakehead infected suspiciously by N. seriolae in an artificial breeding pond were examined. Diseased hybrid snakeheads swam slowly without food intake, and the clinical symptoms included skin wound, anal swelling and ascites, and white granulomatous in liver, spleen, and kidney of fish. Through bacterial isolation, 16S rDNA sequencing, fluorescence in situ hybridization (FISH) and artificial infection experiment, the pathogen was identified as N. seriolae. Furthermore, the spleen samples from diseased and healthy male hybrid snakeheads in the same pond were used for RNA-Seq analysis. A total of 3,512 unique transcripts (unigenes) were identified as differentially expressed genes (DEGs), and 1,886 of them were up-regulated in diseased fish. The expression patterns of 20 DEGs were verified by quantitative polymerase chain reaction (qPCR). Several immune-related pathways and many immune-related genes were identified. qPCR results showed that the expression patterns of immune-related genes in the liver and kidney of diseased fish were comparable to that in the spleen. This study provides deep-sequencing data of hybrid snakehead spleen and will help understand the immune response of hybrid snakehead to N. seriolae. It is also helpful for the biomarker screening of fish-borne Nocardia spp. and the breeding of nocardiosis-resistant fish species.

The dynamic immune responses of Mandarin fish (Siniperca chuatsi) to ISKNV in early infection based on full-length transcriptome analysis and weighted gene co-expression network analysis

Mandarin fish (Siniperca chuatsi) been seriously harmed by infectious spleen and kidney necrosis virus (ISKNV) in recent years, but the early immune response mechanism of infection is still unknown. Here, we performed RNA sequencing on the spleens of mandarin fish infected with ISKNV at 0, 12, 24, 48, and 72 h post-infection (hpi) using short-read Illumina RNA sequencing and long-read Pacific Biosciences isoform sequencing to generate a full-length transcriptome. The immune responses of mandarin fish infected with ISKNV at the molecular level were characterized by RNA-seq analysis and weighted gene co-expression network analysis (WGCNA). A total of 26,528 full-length transcript sequences were obtained. There were 2,729 (1,680 up-regulated and 1,112 down-regulated), 1,874 (1,136 up-regulated and 738 down-regulated), 2,032 (1,158 up-regulated and 847 down-regulated), and 4,176 (2,233 up-regulated and 1,943 down-regulated) differentially expressed genes (DEGs) in mandarin fish at 12, 24, 48, and 72 hpi, compared with uninfected fish, respectively. A total of four modules of co-expressed DEGs identified by WGCNA were significantly positively correlated to the four time points after infection, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the immune-related DEGs in all these modules were mainly enriched in Phagosome, Endocytosis, Herpes simplex infection, and Cytokine-cytokine receptor interaction pathways. Further analysis showed that oher signaling pathways, including CAMs, NOD-like receptor and ER protein processing, Intestinal immune network for IgA production, TLR pathway, and Apoptosis significantly enriched in four modules corresponding to 12, 24, 48, and 72 hpi respectively, had specifically participated in the immune response. Hub genes identified based on the high-degree nodes in the WGCN, including CAM3, IL-8, CCL21, STING, SNX1, PFR and TBK1, and some DEGs such as MHCI, MHCII, TfR, STING, TNF α, TBK1, IRF1, and NF-kB, BCR, IgA and Bcl-XL had involved in dynamic molecular response of mandarin fish to ISKNV infection. In sum, this study provides a set of full-length transcriptome of the spleen tissue of mandarin fish for the first time and revealed a group of immune genes and pathways involved in different temporal responses to ISKNV infection, which has implications for resource conservation and aiding the development of strategies to prevent virus early infection for mandarin fish.

Transcriptomic comparison of ovarian granulosa cells between adult sheep and prepubertal lambs

BACKGROUND

The oocyte development ability of prepubertal animals is significantly lower than that of adult animals. Granulosa cells (GCs) have an important function on regulation of follicular and oocyte development. Therefore, analysis of GC characteristics can be used to explore the developmental mechanism of follicles and oocytes.

RESULTS

In order to understand the possible reasons for the differences in follicle and oocyte development between lambs and adult sheep, we utilized high-throughput sequencing technique to analyze the transcriptome of GCs from follicle-stimulating hormone (FSH) superstimulated adult ewes and prepubertal lambs. Adult ewes were treated with FSH for 3 days (group A) and lambs were FSH-treated for 2 days (group B) or 3 days (group C). Transcriptome analysis of GCs showed that there were 405 and 159 differentially expressed genes from A vs. B and A vs. C, respectively. The results indicated that prolonging the FSH-treatment of lambs made the GC state of lambs more similar to the adult ewes, but there were still a large number of differentially expressed genes between adult ewes and lambs. Further analysis showed that many differently expressed genes were implicated in cell proliferation and apoptosis, oocyte development and follicular ovulation. Cellular examination demonstrated that fatty acid binding protein 4 (FABP4), which was highly expressed in lamb GCs, had a potential of promoting cell apoptosis. Cytoplasmic phospholipase A2 (PLA2G4A), which was expressed lowly in lamb GCs, may be responsible for reduced synthesis of prostaglandins in cells and impaired follicle/oocyte development. In contrast, glutathione S-transferase β-1 (GSTT2B) and forkhead boxO6 (FOXO6) had no apparent effect on the proliferation and apoptosis of GCs.

CONCLUSIONS

Our study found dramatic transcriptomic differences in GCs between lambs and adult sheep, which may explain the possible reasons for the defects of follicle and oocyte development in lambs compared to adult sheep. Our data provides important information for further understanding the mechanism of follicular development in prepubertal animals and improving their oocyte developmental competence.

TSMiner: a novel framework for generating time-specific gene regulatory networks from time-series expression profiles

Time-series gene expression profiles are the primary source of information on complicated biological processes; however, capturing dynamic regulatory events from such data is challenging. Herein, we present a novel analytic tool, time-series miner (TSMiner), that can construct time-specific regulatory networks from time-series expression profiles using two groups of genes: (i) genes encoding transcription factors (TFs) that are activated or repressed at a specific time and (ii) genes associated with biological pathways showing significant mutual interactions with these TFs. Compared with existing methods, TSMiner demonstrated superior sensitivity and accuracy. Additionally, the application of TSMiner to a time-course RNA-seq dataset associated with mouse liver regeneration (LR) identified 389 transcriptional activators and 49 transcriptional repressors that were either activated or repressed across the LR process. TSMiner also predicted 109 and 47 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways significantly interacting with the transcriptional activators and repressors, respectively. These findings revealed the temporal dynamics of multiple critical LR-related biological processes, including cell proliferation, metabolism and the immune response. The series of evaluations and experiments demonstrated that TSMiner provides highly reliable predictions and increases the understanding of rapidly accumulating time-series omics data.

Structure-based identification of inhibitors disrupting the CD2-CD58 interactions

The immune system has very intricate mechanisms of fighting against the invading infections which are accomplished by a sequential event of molecular interactions in the body. One of the crucial phenomena in this process is the recognition of T-cells by the antigen-presenting cells (APCs), which is initiated by the rapid interaction between both cell surface receptors, i.e., CD2 located on T-cells and CD58 located on APCs. Under various pathological conditions, which involve undesired immune response, inhibiting the CD2-CD58 interactions becomes a therapeutically relevant opportunity. Herein we present an extensive work to identify novel inhibiting agents of the CD2-CD58 interactions. Classical molecular dynamics (MD) simulations of the CD2-CD58 complex highlighted a series of crucial CD58 residues responsible for the interactions with CD2. Based on such results, a pharmacophore map, complementary to the CD2-binding site of CD58, was created and employed for virtual screening of ~ 300,000 available compounds. On the ~ 6000 compounds filtered from pharmacophore mapping, ADME screening leads to ~ 350 molecules. Molecular docking was then performed on these molecules, and fifteen compounds emerged with significant binding energy (< - 50 kcal/mol) for CD58. Finally, short MD simulations were performed in triplicate on each complex (i) to provide a microscopic view of the ligand binding and (ii) to rule out possibly weak binders of CD58 from the identified hits. At last, we suggest eight compounds for in vitro testing that were identified as promising hits to bind CD58 with a high binding affinity.

T cell interactions with B cells during germinal center formation, a three-step model

Establishment of effective immunity against invading microbes depends on continuous generation of antibodies that facilitate pathogen clearance. Long-lived plasma cells with the capacity to produce high affinity antibodies evolve in germinal centers (GCs), where B cells undergo somatic hypermutation and are subjected to affinity-based selection. Here, we focus on the cellular interactions that take place early in the antibody immune response during GC colonization. Clones bearing B-cell receptors with different affinities and specificities compete for entry to the GC, at the boundary between the B-cell and T-cell zones in lymphoid organs. During this process, B cells compete for interactions with T follicular helper cells, which provide selection signals required for differentiation into GC cells and antibody secreting cells. These cellular engagements are long-lasting and depend on activation of adhesion molecules that support persistent interactions and promote transmission of signals between the cells. Here, we discuss how interactions between cognate T and B cells are primarily maintained by three types of molecular interactions: homophilic signaling lymphocytic activation molecule (SLAM) interactions, T-cell receptor: peptide-loaded major histocompatibility class II (pMHCII), and LFA-1:ICAMs. These essential components support a three-step process that controls clonal selection for entry into the antibody affinity maturation response in the GC, and establishment of long-lasting antibody-mediated immunity.

Excitable networks controlling cell migration during development and disease

The directed movements of individual, groups, or sheets of cells at specific times in particular locations bring about form and complexity to developing organisms. Cells move by extending protrusions, such as macropinosomes, pseudopods, lamellipods, filopods, or blebs. Although many of the cytoskeletal components within these structures are known, less is known about the mechanisms that determine their location, number, and characteristics. Recent evidence suggests that control may be exerted by a signal transduction excitable network whose components and activities, including Ras, PI3K, TorC2, and phosphoinositides, self-organize on the plasma membrane and propagate in waves. The waves drive the various types of protrusions, which in turn, determine the modes of cell migration. Acute perturbations at specific points in the network produce abrupt shifts in protrusion type, including transitions from pseudopods to filopods or lamellipods. These observations have also contributed to a delineation of the signal transduction network, including candidate fast positive and delayed negative feedback loops. The network contains many oncogenes and tumor suppressors, and other molecules which have recently been implicated in developmental and metabolic abnormalities. Thus, the concept of signal transduction network excitability in cell migration can be used to understand disease states and morphological changes occurring in development.

MicroRNA Changes in Firefighters

Objectives:

Firefighters have elevated cancer incidence and mortality rates. MicroRNAs play prominent roles in carcinogenesis, but have not been previously evaluated in firefighters.

Methods:

Blood from 52 incumbent and 45 new recruit nonsmoking firefighters was analyzed for microRNA expression, and the results adjusted for age, obesity, ethnicity, and multiple comparisons.

Results:

Nine microRNAs were identified with at least a 1.5-fold significant difference between groups. All six microRNAs with decreased expression in incumbent firefighters have been reported to have tumor suppressor activity or are associated with cancer survival, and two of the three microRNAs with increased expression in incumbent firefighters have activities consistent with cancer promotion, with the remaining microRNA associated with neurological disease.

Conclusion:

Incumbent firefighters showed differential microRNA expression compared with new recruits, providing potential mechanisms for increased cancer risk in firefighters.

The actomyosin network is influenced by NMHC IIA and regulated by CrpF46, which is involved in controlling cell migration

When a cell migrates, the centrosome positions between the nucleus and the leading edge of migration via the microtubule system. The protein Crp^F46 (centrosome-related protein F46) has a known role during mitosis and centrosome duplication. However, how Crp^F46 efficiently regulates centrosome-related cell migration is unclear. Here, we report that knockdown of Crp^F46 resulted in the disruption of microtubule arrangement, with impaired centrosomal reorientation, and slowed down cell migration. In cells that express low levels of Crp^F46, stress fibers were weakened, which could be rescued by recovering Flag-Crp^F46. We also found that Crp^F46 interacted with non-muscle myosin high chain IIA (NMHC IIA) and that its three coiled-coil domains are pivotal for its binding to NMHC IIA. Additionally, analyses of phosphorylation of NMHC IIA and RLC (regulatory light chain) demonstrated that Crp^F46 was associated with myosin IIA during filament formation. Indirect immunofluorescence images indicated that NM IIA filaments were inhibited when Crp^F46 was under-expressed. Thus, Crp^F46 regulates cell migration by centrosomal reorientation and altering the function of the actomyosin network by controlling specific phosphorylation of myosin.

Identification of an intercellular cell adhesion molecule-1 homologue from grass carp: Evidence for its involvement in the immune cell adhesion in teleost

Intercellular cell adhesion molecule-1 (ICAM-1) is a single-chain transmembrane glycoprotein which plays key roles in transendothelial migration of leukocytes and interaction between antigen presenting cells and T cells. In teleost, information of cell adhesion-related molecules is still lacking. In this study, we identified a gene from grass carp sharing similar exon and intron organization with human ICAM-1. Cloning and in silico analysis of its homologues in zebrafish and other two cyprinid fishes, respectively demonstrated the existence of the gene in these fishes. Moreover, the molecular features of these genes in fishes were conserved compared with human ICAM-1. In grass carp, the transcripts of this gene were detected with high levels in heart and liver and its mRNA expression in headkidney leukocytes was induced by Il-1β. Overexpression of this molecule in COS-7 cells could increase the adhesion of the cells with grass carp peripheral blood lymphocytes (PBLs), and the adhesion was further enhanced by lipopolysaccharide stimulation on PBLs. Further studies revealed that the mRNA levels of lymphocyte function-associated antigen-1, a ligand for ICAM-1, were much higher in the PBLs adhering to the COS-7 cells with overexpressing this molecule than in the PBLs alone. These results collectively showed that the newly cloned cDNA encodes grass carp intercellular cell adhesion molecule-1 (Icam-1) and it can mediate the adhesion of PBLs. This provides functional evidence for the existence of Icam-1 in teleost and will facilitate investigation on the transendothelial migration of leukocytes in fish species.

Quantitative N-glycoproteomics of milk fat globule membrane in human colostrum and mature milk reveals changes in protein glycosylation during lactation

The present study profiled the N-glycoproteome and quantified the changes of N-glycosylation site occupancy of MFGM proteins during lactation.

Qualitative differences in T-cell activation by dendritic cell-derived extracellular vesicle subtypes

Exosomes, nano-sized secreted extracellular vesicles (EVs), are actively studied for their diagnostic and therapeutic potential. In particular, exosomes secreted by dendritic cells (DCs) have been shown to carry MHC-peptide complexes allowing efficient activation of T lymphocytes, thus displaying potential as promoters of adaptive immune responses. DCs also secrete other types of EVs of different size, subcellular origin and protein composition, whose immune capacities have not been yet compared to those of exosomes. Here, we show that large EVs (lEVs) released by human DCs are as efficient as small EVs (sEVs), including exosomes, to induce CD4+ T-cell activation in vitro When released by immature DCs, however, lEVs and sEVs differ in their capacity to orient T helper (Th) cell responses, the former favouring secretion of Th2 cytokines, whereas the latter promote Th1 cytokine secretion (IFN-γ). Upon DC maturation, however, these functional differences are abolished, and all EVs become able to induce IFN-γ. Our results highlight the need to comprehensively compare the functionalities of EV subtypes in all patho/physiological systems where exosomes are claimed to perform critical roles.

ICAMs support B cell interactions with T follicular helper cells and promote clonal selection

The molecular mechanism governing affinity-based B cell selection for germinal center colonization is unclear. Zaretsky et al. show that B cell ICAMs promote efficient B cell selection for clonal expansion by supporting sustained interactions with T follicular helper cells.

The germinal center (GC) reaction begins with a diverse and expanded group of B cell clones bearing a wide range of antibody affinities. During GC colonization, B cells engage in long-lasting interactions with T follicular helper (Tfh) cells, a process that depends on antigen uptake and antigen presentation to the Tfh cells. How long-lasting T–B interactions and B cell clonal expansion are regulated by antigen presentation remains unclear. Here, we use in vivo B cell competition models and intravital imaging to examine the adhesive mechanisms governing B cell selection for GC colonization. We find that intercellular adhesion molecule 1 (ICAM-1) and ICAM-2 on B cells are essential for long-lasting cognate Tfh–B cell interactions and efficient selection of low-affinity B cell clones for proliferative clonal expansion. Thus, B cell ICAMs promote efficient antibody immune response by enhancement of T cell help to cognate B cells.

Orchestrating Lymphocyte Polarity in Cognate Immune Cell-Cell Interactions

The immune synapse (IS) is a specialized structure established between different immune cells that fulfills several functions, including a role as a communication bridge. This intimate contact between a T cell and an antigen-presenting cell promotes the proliferation and differentiation of lymphocytes involved in the contact. T-cell activation requires the specific triggering of the T-cell receptor (TCR), which promotes the activation of different signaling pathways inducing the polarization of the T cell. During this process, different adhesion and signaling receptors reorganize at specialized membrane domains, concomitantly to the polarization of the tubulin and actin cytoskeletons, forming stable polarization platforms. The centrosome also moves toward the IS, driving the movement of different organelles, such as the biosynthetic, secretory, degrading machinery, and mitochondria, to sustain T-cell activation. A proper orchestration of all these events is essential for T-cell effector functions and the accomplishment of a complete immune response.

MINDEC-An Enhanced Negative Depletion Strategy for Circulating Tumour Cell Enrichment

Most current methods of circulating tumour cell (CTC) enrichment target the epithelial protein EpCAM, which is commonly expressed in adenocarcinoma cells. However, such methods will not recover the fraction of CTCs that have a non-epithelial phenotype due to epithelial–mesenchymal transition. For phenotype-independent CTC enrichment, we developed a new enhanced negative depletion strategy—termed MINDEC—that is based on multi-marker (CD45, CD16, CD19, CD163, and CD235a/GYPA) depletion of blood cells rather than targeted enrichment of CTCs. Here we validated the performance of MINDEC using epithelial and mesenchymal cancer cell lines, demonstrating a mean recovery of 82 ± 10%, high depletion (437 ± 350 residual white blood cells (WBCs)/mL peripheral blood), linearity between spiked and recovered cells (correlation coefficient: r = 0.995), and a low detection limit (≥1 cell recovered in all four replicates spiked with 3 cells). For clinical validation of this method, we enumerated CTCs in peripheral blood samples from patients with metastatic pancreatic cancer, detecting CTCs in 15 of 21 blood samples (71%) from 9 patients. The promising performance of the MINDEC enrichment strategy in our study encourages validation in larger clinical trials.

The role of epithelial cells in the initiation and perpetuation of autoimmune lesions: lessons from Sjögren’s syndrome (autoimmune epithelitis)

Sjögren’s syndrome (SS) is a chronic autoimmune disease affecting epithelial tissues. Exocrine glands are the primary target and their functional impairment comes as a result of immune attack of epithelial cells of the affected organs (autoimmune epithelitis). In this interplay, the role of the epithelial cell is pivotal. Extensive data point to an intrinsically activated status. Moreover, the epithelial cells possess all the features needed in order to act as non-professional antigen presenting cells. Through apoptosis and exosomes release endocellular antigens contributing to tolerance breakdown. In addition, produce cytokines and chemokines that recruit lymphocytes in the immunopathogenic lesion. Herein, we review all the aforementioned aspects of the epithelial activity that lead to the perpetuation of the lesion as well as the probable viral factors for the intrinsic activation. Finally, we propose a model for SS pathogenesis that integrates the knowledge accumulated during the last decade.

Signaling networks that regulate cell migration

SUMMARY

Stimuli that promote cell migration, such as chemokines, cytokines, and growth factors in metazoans and cyclic AMP in Dictyostelium, activate signaling pathways that control organization of the actin cytoskeleton and adhesion complexes. The Rho-family GTPases are a key convergence point of these pathways. Their effectors include actin regulators such as formins, members of the WASP/WAVE family and the Arp2/3 complex, and the myosin II motor protein. Pathways that link to the Rho GTPases include Ras GTPases, TorC2, and PI3K. Many of the molecules involved form gradients within cells, which define the front and rear of migrating cells, and are also established in related cellular behaviors such as neuronal growth cone extension and cytokinesis. The signaling molecules that regulate migration can be integrated to provide a model of network function. The network displays biochemical excitability seen as spontaneous waves of activation that propagate along the cell cortex. These events coordinate cell movement and can be biased by external cues to bring about directed migration.

Location, location, location: the impact of migratory heterogeneity on T cell function

T cell migration is crucial for an effective adaptive immune response to invading pathogens. Naive and memory T cells encounter pathogen antigens, become activated, and differentiate into effector cells in secondary lymphoid tissues, and then migrate to the site(s) of infection where they exert effector activities that control and eliminate pathogens. To achieve activation, efficient effector function, and good memory formation, T cells must traffic between lymphoid and non-lymphoid tissues within the body. This complex process is facilitated by chemokine receptors, selectins, CD44, and integrins that mediate the interactions of T cells with the environment. The expression patterns of these migration receptors (MR) dictate the tissues into which the effector T cells migrate and enable them to occupy specific niches within the tissue. While MR have been considered primarily to facilitate cell movement, we highlight how the heterogeneity of signaling through these receptors influences the function and fate of T cells in situ. We explore what drives MR expression heterogeneity, how this affects migration, and how this impacts T cell effector function and memory formation.

The reorientation of cell nucleus promotes the establishment of front-rear polarity in migrating fibroblasts

The establishment of cell polarity is an essential step in the process of cell migration. This process requires precise spatiotemporal coordination of signaling pathways that in most cells create the typical asymmetrical profile of a polarized cell with nucleus located at the cell rear and the microtubule organizing center (MTOC) positioned between the nucleus and the leading edge. During cell polarization, nucleus rearward positioning promotes correct microtubule organizing center localization and thus the establishment of front-rear polarity and directional migration. We found that cell polarization and directional migration require also the reorientation of the nucleus. Nuclear reorientation is manifested as temporally restricted nuclear rotation that aligns the nuclear axis with the axis of cell migration. We also found that nuclear reorientation requires physical connection between the nucleus and cytoskeleton mediated by the LINC (linker of nucleoskeleton and cytoskeleton) complex. Nuclear reorientation is controlled by coordinated activity of lysophosphatidic acid (LPA)-mediated activation of GTPase Rho and the activation of integrin, FAK (focal adhesion kinase), Src, and p190RhoGAP signaling pathway. Integrin signaling is spatially induced at the leading edge as FAK and p190RhoGAP are predominantly activated or localized at this location. We suggest that integrin activation within lamellipodia defines cell front, and subsequent FAK, Src, and p190RhoGAP signaling represents the polarity signal that induces reorientation of the nucleus and thus promotes the establishment of front-rear polarity.

Roles of substance P and ATP in the subepithelial fibroblasts of rat intestinal villi

The ingestion of food and water induces chemical and mechanical signals that trigger peristaltic reflexes and also villous movement in the gut. In the intestinal villi, subepithelial fibroblasts under the epithelium form contractile cellular networks and closely contact to the varicosities of substance P and nonsubstance P afferent neurons. Subepithelial fibroblasts of the duodenal villi possess purinergic receptor P2Y1 and tachykinin receptor NK1. ATP and substance P induce increase in intracellular Ca(2+) and cell contraction in subepithelial fibroblasts. They are highly mechanosensitive and release ATP by mechanical stimuli. Released ATP spreads to form an ATP "cloud" with nearly 1μM concentration and activates the surroundings via P2Y1 and afferent neurons via P2X receptors. These findings suggest that villous subepithelial fibroblasts and afferent neurons interact via ATP and substance P. This mutual interaction may play important roles in the signal transduction of mechano reflex pathways including a coordinate villous movement and also in the maturation of the structure and function of the intestinal villi.

Genome-wide expression analysis in Down syndrome: insight into immunodeficiency

Down syndrome (DS) is caused by triplication of Human chromosome 21 (Hsa21) and associated with an array of deleterious phenotypes, including mental retardation, heart defects and immunodeficiency. Genome-wide expression patterns of uncultured peripheral blood cells are useful to understanding of DS-associated immune dysfunction. We used a Human Exon microarray to characterize gene expression in uncultured peripheral blood cells derived from DS individuals and age-matched controls from two age groups: neonate (N) and child (C). A total of 174 transcript clusters (gene-level) with eight located on Hsa21 in N group and 383 transcript clusters including 56 on Hsa21 in C group were significantly dysregulated in DS individuals. Microarray data were validated by quantitative polymerase chain reaction. Functional analysis revealed that the dysregulated genes in DS were significantly enriched in two and six KEGG pathways in N and C group, respectively. These pathways included leukocyte trans-endothelial migration, B cell receptor signaling pathway and primary immunodeficiency, etc., which causally implicated dysfunctional immunity in DS. Our results provided a comprehensive picture of gene expression patterns in DS at the two developmental stages and pointed towards candidate genes and molecular pathways potentially associated with the immune dysfunction in DS.

Microspectroscopy reveals mechanisms of lymphocyte activation

The immunological synapse (IS) regulates immune responses by integrating extracellular stimuli into intracellular signalling networks, which causes leukocyte differentiation and effector functions. The dynamic spatial organisation of molecules at the IS was initially characterised by wide-field fluorescence microscopy of cell conjugates and cells interacting with planar lipid bilayers. These methods showed stable supramolecular clusters of several microns in size, which were proposed to be responsible for sustained signalling and cell-cell adhesion. The recent emergence of microspectroscopy techniques with higher spatial and temporal resolution nonetheless reveals the complex dynamics of molecular reactions that mediate IS assembly and function. This review describes microspectroscopy-based in vitro experimental approaches for imaging the molecular dynamics at the IS, as well as their contributions and open questions in the field. It also describes experimental methods to obtain quantitative parameters of dynamic biochemical reactions in living cells, and discusses about the important role of quantitative imaging and theoretical science in our understanding of molecular mechanisms underlying lymphocyte activation.

Mechanisms and mediators of inflammation: potential models for skin rejection and targeted therapy in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) is an effective treatment option for patients suffering from limb loss or severe disfigurement. However, postoperative courses of VCA recipients have been complicated by skin rejection, and long-term immunosuppression remains a necessity for allograft survival. To widen the scope of this quality-of-life improving procedure minimization of immunosuppression in order to limit risks and side effects is needed. In some aspects, the molecular mechanisms and dynamics of skin allograft rejection seem similar to inflammatory skin conditions. T cells are key players in skin rejection and are recruited to the skin via activation of adhesion molecules, cytokines, and chemokines. Blocking these molecules has not only shown success in the treatment of inflammatory dermatoses, but also prolonged graft survival in various models of solid organ transplantation. In addition to T cell recruitment, ectopic lymphoid structures within the allograft associated with chronic rejection in solid organ transplantation might contribute to the strong alloimmune response towards the skin. Selectively targeting the molecules involved offers exciting novel therapeutic options in the prevention and treatment of skin rejection after VCA.

Interplay of polarity proteins and GTPases in T-lymphocyte function

Polarity refers to the asymmetric distribution of different cellular components within a cell and is central to many cell functions. In T-cells, polarity regulates the activation, migration, and effector function of cytotoxic T-cells (CTLs) during an immune response. The regulation of asymmetric cell division by polarity proteins may also dictate CTL effector and memory differentiation following antigen presentation. Small GTPases, along with their associated polarity and adaptor proteins, are critical for mediating the polarity changes necessary for T-cell activation and function, and in turn, are regulated by guanine exchange factors (GEFS) and GTPase activating proteins (GAPS). For example, a novel GEF, dedicator of cytokinesis 8 (DOCK8) was recently identified as a regulator of immune cell function and mutations in DOCK8 have been detected in patients with severe combined immunodeficiency. Both B and T-cells from DOCK8 mutant mice form defective immunological synapses and have abnormal functions, in addition to impaired immune memory development. This paper will discuss the interplay between polarity proteins and GTPases, and their role in T-cell function.

Effects of SCR-3 on the immunosuppression accompanied with the systemic inflammatory response syndrome

Steroid receptor coactivator-3 (SRC-3) is a multifunctional protein that plays an important role in mammary gland growth, development, and tumorigenesis. In this study, SCR-3 gene knockout mice were used to study the effects of SCR-3 on the immunosuppression accompanied with systemic inflammatory response syndrome (SIRS). Bacterial clearance assay was performed by blood culture and frozen sections, and the results showed that the absence of SCR-3 protein serious damaged the innate immune system and the body's ability to inactivate or phagocytosis of bacteria was significantly decreased, and the absence of SCR-3 protein also weakened phagocytes' ability to degrade bacteria and their metabolites. Furthermore, animal model of inflammatory reaction was established and the immune function was determined, and the results revealed that SRC-3 protein may play an important role in maintenance of T-cells' immune function, and severe T-cell immune function disorder would be resulted once SRC-3 protein is missing. In addition, the results of our study showed the steady-state of lymphocyte subsets was destroyed after SIRS, leading the suppression of cellular immune function, and the absence of SCR-3 protein may aggravate the suppression of T-lymphocyte function. Therefore, the present study demonstrated that the absence of SCR-3 protein would aggravate immunosuppression. In addition, SRC-3 protein is a significant regulator of infection and inflammation, and SRC-3 protein play an essential role in the development of immunosuppression accompanied with SIRS.

Interaction of allergens, major histocompatibility complex molecules, and T cell receptors: a 'ménage à trois' that opens new avenues for therapeutic intervention in type I allergy

T cells are major players in the initiation and perpetuation of the allergic immune response. In this review, we summarize the current knowledge on allergen recognition by T lymphocytes and address the components of the trimeric recognition complex: T cell receptors, major histocompatibility complex molecules, and allergen-derived peptides. Furthermore, possible implications of this scientific background for future therapeutic developments are discussed.

The neuronal protein Kidins220/ARMS associates with ICAM-3 and other uropod components and regulates T-cell motility

Kinase D interacting substrate of 220 kDa (Kidins220), also known as ankyrin repeat-rich membrane spanning (ARMS), is a protein that is mainly expressed in brain and neural cells where its function is only starting to be characterized. Here, we show that Kidins220/ARMS is also expressed in T lymphocytes where it is highly concentrated at the uropod of polarized T cells. In this cellular model, Kidins220/ARMS colocalizes with typical uropod T-cell molecules and coimmunoprecipitates with ICAM-3. Furthermore, Kidins220/ARMS associates with raft domains at the uropod and coimmunoprecipitates with caveolin-1, a molecule we show here to be also expressed in T cells. Importantly, induction of morphological polarization in primary T lymphocytes and Jurkat cells enhances Kidins220/ARMS colocalization with ICAM-3. Conversely, disruption of cell polarity provokes Kidins220/ARMS redistribution from the uropod to other cellular regions and drastically impairs its association with ICAM-3 in a protein kinase C-dependent manner. Finally, Kidins220/ARMS knockdown in human polarized T-cell lines promotes both basal and stromal cell-derived factor-1α-induced directed migration, identifying a novel function for this molecule. Altogether, our findings show that Kidins220/ARMS is a novel component of the uropod involved in the regulation of T-cell motility, an essential process for the immune response.

PI3K links NKG2D signaling to a CrkL pathway involved in natural killer cell adhesion, polarity, and granule secretion

The NK cell-activating receptor NKG2D plays a critical role in the destruction of malignant cells, but many of the cell-signaling mechanisms governing NKG2D-mediated cellular cytotoxicity are unknown. We have identified an NKG2D-mediated signaling pathway that governs both conjugate formation and cytotoxic granule polarization. We demonstrate that an interaction between the regulatory subunit of PI3K, p85, and the adaptor protein CrkL is required for efficient NKG2D-mediated cellular cytotoxicity. We show decreased NK cell-target cell conjugate formation in NK cells treated with PI3K inhibitors or depleted of CrkL. Independent of adhesion, we find that microtubule organization center polarization toward target cells expressing the NKG2D ligand MICA or toward anti-NKG2D-coated beads is impaired in the absence of CrkL. Ab-stimulated granule release is also impaired in NK cells depleted of CrkL. Furthermore, our data indicate that the small Ras family GTPase Rap1 is activated downstream of NKG2D engagement in a PI3K- and CrkL-dependent manner and is required for conjugate formation, MTOC (microtubule organizing center) polarization, and NKG2D-dependent cellular cytotoxicity. Taken together, our data identify an NKG2D-activated signaling pathway that collectively orchestrates NK cell adhesion, cell polarization, and granule release.

HLA-Cw4 expression on porcine endothelial cells reduces cytotoxicity and adhesion mediated by CD158a+ human NK cells

BACKGROUND

Human natural killer (NK) cell-mediated cytotoxicity represents a hurdle in pig-to-human xenotransplantation. It was previously reported that the expression of human major histocompatibility complex class I molecules, including HLA-B27, -Cw3, -E, and -G, partially protects porcine endothelial cells (pEC) from human NK-mediated cytotoxicity and that HLA-G inhibits NK adhesion to pEC. Here, we tested if HLA-Cw4 expression on pEC alone, or concurrently with HLA-Cw3, prevents human NK adhesion and cytotoxicity against pEC via recognition of the killer-cell immunoglobulin-like receptors (KIR) CD158a (KIR2DL1) and CD158b (KIR2DL2/3), respectively.

METHODS

Two pEC lines (2A2 and PEDSV.15) were transfected with HLA-Cw3 and HLA-Cw4. HLA and KIR expression on porcine and human cells were analyzed by flow cytometry. The effect of HLA expression on pEC on human NK-mediated cytotoxicity and adhesion was tested by (51)Cr-release and dynamic adhesion assays, respectively.

RESULTS

HLA-Cw4 expression on pEC reduced cytotoxicity mediated by CD158a(+) polyclonal human NK cells by an average of 58%, and by CD158a(bright) NK cell clones by 68%, but not by NK cells expressing low levels of CD158. Co-expression of HLA-Cw3 and HLA-Cw4 on pEC did not mediate further protection against NK cytotoxicity. The expression of HLA-Cw4 reduced the adhesion of human NK cells on pEC by a mean of 53%.

CONCLUSIONS

While transgenic expression of HLA-Cw4 on pEC reduces NK cell adhesion and cytotoxicity, co-expression with HLA-Cw3 is not sufficient to completely overcome human NK-mediated cytotoxicity in vitro.

Modulation of allergen-specific T-lymphocyte function by virus-like particles decorated with HLA class II molecules

BACKGROUND

T(H)2 lymphocytes play an important role in the induction and maintenance phase of type I allergy. Modulation of the responses of T(H)2 lymphocytes by novel forms of antigen-presenting platforms may help shape the immune response to allergen and palliate allergic diseases.

OBJECTIVE

To present HLA class II/allergen-peptide complexes on virus-like particles (VLPs) and to evaluate their potential to modulate allergen-specific T-cell responses.

METHODS

Virus-like particles that express the immunodominant T-cell epitope Art v 1(25-34) of the major mugwort pollen allergen in the context of HLA-DR1 and costimulatory molecules were produced by transfection of 293 cells. The effect of VLPs on IL-2 promoter activity, proliferation, and cytokine production of allergen-specific T cells derived from donors with and without mugwort pollen allergy was determined.

RESULTS

Flow-cytometric analyses showed that HLA class II molecules, invariant chain::Art v 1 fusion proteins, and costimulatory molecules were expressed on 293 cells. Biochemical analyses confirmed that these molecules were efficiently targeted to VLPs. The engineered VLPs activated Art v 1-specific T cells in a costimulation-dependent manner. VLPs lacking costimulators induced T-cell unresponsiveness, which was overcome by addition of exogenous IL-2. Costimulation could be provided by CD80, CD86, or CD58 and induced distinct cytokine profiles in allergen-specific T cells. Unlike the other costimulatory molecules, CD58 induced IL-10/IFN-gamma-secreting T cells.

CONCLUSION

Virus-like particles represent a novel, modular, acellular antigen-presenting system able to modulate the responses of allergen-specific T cells in a costimulator-dependent fashion. Allergen-specific VLPs show promise as tools for specific immunotherapy of allergic diseases.

Disturbances of acquired immunity in hemodialysis patients

Acquired immunity disturbances in hemodialysis (HD) patients are many and diverse. They are caused by uremia per se, the HD procedure, chronic renal failure complications, and therapeutic interventions for their treatment. Current data suggest that acquired immunity disturbances in HD patients concern mainly the T-lymphocyte and the antigen-presenting cell (APC). The T-lymphocyte-dependent immune response is deficient, predisposing to infections and inadequate response to vaccinations. In addition, APCs are preactivated, which seems to be responsible for the malnutrition-inflammation-atherosclerosis syndrome, and also affects T-lymphocyte function. At the molecular level it is assumed that the interaction between the APC and the T-lymphocyte is impaired. This disturbance is likely to concern the signal that results from the interaction between the major histocompatibility complex:peptide complex on APC surfaces and T-cell receptors on T-lymphocyte surfaces, or the signal that results from the interaction among the co-receptors of these two cells. The aim of the present review was to collect and classify the available clinical and experimental data in this area. Although many pieces are still missing from the puzzle, a better understanding of the responsible molecular mechanisms, will potentially lead to increased survival and a better quality of life in HD patients.

Polarization of endosomal SNX27 in migrating and tumor-engaged Natural Killer cells

Polarization is a critical mechanism for the proper functioning of many cell types. For lymphocytes, it is essential in a variety of processes, including migration from the blood to other tissue sites and vice versa. In NK cells and CTLs, the cytotoxic granule delivery mechanism requires polarization for granule movement to the immunological synapse (IS), in killing tumor and virus-infected cells. Recently, it has become apparent that endosomes are also involved in the cytotoxic mechanism. Using an in vitro conjugation approach, we show that in NK-92 cells, endosomal Sorting Nexin 27 (SNX27) polarizes to the IS during tumor cell engagement in a distinct compartment adjacent to the cytotoxic granules. We also show that SNX27 polarizes to the apical membrane, opposite the uropod, during NK cell migration. These previously unreported results indicate that SNX27 is a participant in NK cell polarization, as a mediator or target of the mechanism.

Depressed T cell-derived IFN-gamma following trauma-hemorrhage: a potential mechanism for diminished APC responses

INTRODUCTION

Prolonged immunosuppression has been demonstrated after trauma-hemorrhage resulting in an increased susceptibility to sepsis. The contribution of antigen-presenting cells (APC) vs T cells to this diminished immune response, however, remains unknown.

MATERIALS AND METHODS

To study this, male mice were trauma-hemorrhaged (35 +/- 5 mmHg for 90 min and resuscitation) or sham operated. At 24 h thereafter, spleens were harvested and T cells (via Microbeads) and APC (via adherence) were isolated. Cocultures of combined T cells and APC were established for 48 h, stimulated with ConA and LPS. The T cell-derived cytokine IFN-gamma and IL-12 for APC responses were measured in the supernatants by the multiplex assay.

RESULTS

The release of IFN-gamma was suppressed by T cells after trauma-hemorrhage irrespective of whether sham or trauma-hemorrhage APC were added. Trauma-hemorrhaged APC did not affect T cells-derived IFN-gamma release by sham T cells. In contrast, trauma-hemorrhaged T cells depressed the release of IL-12 by APC. The release of IL-12 by trauma-hemorrhaged APC was not altered when sham T cells were cocultured.

CONCLUSION

Prolonged immunosuppression after trauma-hemorrhage appears to be predominantly due to diminished T cell function. Thus, attempts to prevent immunodysfunction should be directed towards T cells.

Protein transduction as a means of effective manipulation of Cdc42 activity in primary T cells

The Rho family GTPase Cdc42 is a critical regulator of cellular polarization from yeast to man. An analysis of its function in T cell activation is therefore of interest. This analysis poses two substantial challenges, similar to the analysis of many other critical T cell signaling intermediates. First, Cdc42 is required for development and cell survival, necessitating short-term manipulation of its activity. Second, Cdc42 is likely involved in multiple signaling pathways, requiring approaches to distinguish multiple roles. To address these challenges, we first determined and quantified spatio-temporal patterns of Cdc42 activity using live cell video fluorescence microscopy. This generates hypotheses at which times and locations Cdc42 might play possibly distinct roles. Second and as the focus of this manuscript, we employed protein transduction to manipulate Cdc42 activity for the generation of causality. Protein transduction allows such manipulation to be short-term, quantitative, and with multiple reagents. Here, we characterize uptake, retention, and subcellular distribution of protein transduction reagents. We describe how a more quantitative single cell analysis of Cdc42 activity provides superior distinction between experimental conditions. And we show how we have used dose responses of the protein transduction reagents to minimize side effects while retaining efficacy. We suggest that our strategy is an important complement to more established techniques to study protein function in primary T cells, in particular in the investigation of signaling intermediates that are essential for cell survival and regulate multiple aspects of T cell activation.

Relevance of DC-SIGN in DC-induced T cell proliferation

The role of dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) in DC-T cell communication was assessed by analyzing the effect of DC-SIGN-blocking mAb in MLR. The results show that the degree of inhibition by DC-SIGN and LFA-1 mAb depends on the magnitude of the MLR and the maturation status of the DC. Addition of DC-SIGN mAb at several time-points during MLR showed that DC-SIGN is involved early on in DC-T cell contacts. This initial role is masked by strong adhesive and costimulatory mechanisms, indicating a short-lived effect of DC-SIGN in DC-T cell interactions. To examine this concept in more detail, the percentage of PBL capable of binding DC-SIGN was determined. Analysis of several donors revealed that 1-20% PBL bind to beads coated with recombinant DC-SIGN, and the DC-SIGN-binding cells comprised all major cell subsets found in blood. PBL isolated from a donor with high DC-SIGN-binding capacity were more prone to blocking by DC-SIGN mAb in MLR than PBL from a donor with low DC-SIGN-binding capacity. This study indicates an initial and transient role for DC-SIGN in T cell proliferation, which becomes apparent when T cell proliferation is low and when the percentage of DC-SIGN binding PBL is high.