B-cell agonists up-regulate AID and APOBEC3G deaminases, which induce IgA and IgG class antibodies and anti-viral function

B cells express two critical deaminases in the development of adaptive and innate immunity. Activation-induced cytidine deaminase (AID) functions in class switch recombination, somatic hypermutation and may result in affinity maturation of antibodies. Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G (APOBEC3G; A3G) is an innate anti-retroviral factor that inhibits HIV replication. We have studied a number of B-cell agonists with the aim of identifying the most effective agents that will up-regulate both deaminases and thereby enhance adaptive and innate immunity. CD40 ligand (CD40L) with interleukin-4 or HLA-class II antibodies significantly up-regulated both AID and A3G in isolated human CD19(+) B cells. The functions of these deaminases were demonstrated by enhancement of B-cell surface expression of IgA and IgG and inducing significantly higher IgA and IgG4 antibodies. An enhanced A3G function was then demonstrated by inhibition of HIV-1 replication in co-culture of CD4(+) T cells with autologous B cells, treated with CD40L and CD4 or HLA antibodies, compared with unstimulated human B cells. The dual B-cell-induced deaminase functions may be critical in IgA and IgG antibodies inhibiting pre-entry and A3G that of post-entry HIV-1 transmission and suggests a novel strategy of immunization, especially relevant to mucosal infections.

Innate immunity and HIV-1 infection

HIV-1 is predominantly transmitted through mucosal tissues, targeting CD4(+)CCR5(+) T cells, 50% of which are destroyed within 2 weeks of infection. Conventional vaccination strategies have so far failed to prevent HIV-1 infection. Neither antibodies nor cytotoxic lymphocytes are capable of mounting a sufficiently rapid immune response to prevent early destruction of these cells. However, innate immunity is an early-response system, largely independent of prior encounter with a pathogen. Innate immunity can be classified into cellular, extracellular, and intracellular components, each of which is exemplified in this review by γδ T cells, CC chemokines, and APOBEC3G, respectively. First, γδ T cells are found predominantly in mucosal tissues and produce cytokines, CC chemokines, and antiviral factors. Second, the CC chemokines CCL-3, CCL-4, and CCL-5 can be upregulated by immunization of macaques with SIVgp120 and gag p27, and these can bind and downmodulate CCR5, thereby inhibiting HIV-1 entry into the host cells. Third, APOBEC3G is generated and maintained following rectal mucosal immunization in rhesus macaques for over 17 weeks, and the innate anti-SIV factor is generated by CD4(+)CD95(+)CCR7(-) effector memory T cells. Thus, innate anti-HIV-1 or SIV immunity can be linked with immune memory, mediated by CD4(+) T cells generating APOBEC3G. The multiple innate functions may mount an early anti-HIV-1 response and either prevent viral transmission or contain the virus until an effective adaptive immune response develops.

[Locking plates for osteosyntheses of corrective osteotomies in paediatric orthopaedic and neuroorthopaedic patients]

BACKGROUND

Modern locking plates are widely used for the treatment of adult orthopaedic and trauma patients. Sporadic descriptions of their advantages now exist for paediatric trauma patients. Publications concerning their implantation in paediatric orthopaedic and neuroorthopaedic patients are still scarce even though it is well known that the compliance of children and adolescents is limited and that rapid mobilisation is essential for patients with disorders of neurological origin or bone metabolism to avoid developmental setbacks and perioperative fractures.

PATIENTS AND METHODS

The principle of the locking plate system also described as internal fixateur is based on the thread bolting of the screwheads within the plate. This results in high initial stability and thus high initial loading capacity. Furthermore, it is possible to preserve soft tissue and periosteum which leads to less impaired biological bone healing. Between February 2008 and March 2010 locking plates were used for osteosynthesis in our department in 16 paediatric patients with 20 corrective osteotomies. All patients suffered from either neurological disorders or diseases with alteration of the bone metabolism. The outcome was analysed concerning safety, complications, practicability, mobilisation, consolidation of the osteotomy, loss of correction, as well as complications with the removal of the implants.

RESULTS

Seven of the treated patients suffered from neurological disorders such as cerebral palsy or spina bifida, 9 patients had diseases with local or systemic alteration of their bone metabolism such as vitamin D deficiency and phosphate diabetes. The average age of the patients at the time of surgery was 11.18 (5-18) years. Implant-associated complications were not seen in this patient group, especially no implant failures. Mobilisation was achieved without cast treatment with at least partial weight-bearing within the first postoperative week in most cases. Loss of correction or problems with implant removal did not occur. 18 of the 20 osteotomy sites were completely healed at the 12 week follow-up.

CONCLUSION

Locking plates are a safe and effective treatment device not only for adult trauma patients but also for the treatment of children and adolescents. When stabilisation of corrective osteotomies is performed with locking plates especially young patients benefit from this technique since mobilisation can be started earlier as compared to the use of non-angle stable plates or wires and cast immobilisation becomes unneccessary. The surgeon needs to know the range of products to pick the best implant regarding the growing skeleton's special anatomy. When choosing implants for patients with reduced bone density or impaired motor abilities as in cerebral palsy, spina bifida, and other systemic disorders, locking plates have to be taken into account to facilitate mobilisation and to avoid setbacks in motor development as well as pressure ulcers from casts. Clinical studies have to evaluate if early mobilisation combined with shorter inpatient treatment and less time and cost consuming postoperative physiotherapy or rehabilitation justify the use of the more expensive locking plates for the treatment of otherwise healthy patients.

The melanocortin receptor agonist NDP-MSH impairs the allostimulatory function of dendritic cells

As alpha-melanocyte-stimulating hormone (alpha-MSH) is released by immunocompetent cells and has potent immunosuppressive properties, it was determined whether human dendritic cells (DCs) express the receptor for this hormone. Reverse transcription-polymerase chain reaction detected messenger RNA specific for all of the known melanocortin receptors in DCs. Mixed lymphocyte reactions also revealed that treatment with [Nle(4), DPhe(7)]-alpha-MSH (NDP-MSH), a potent alpha-MSH analogue, significantly reduced the ability of DCs to stimulate allogeneic T cells. The expression of various cell surface adhesion, maturation and costimulatory molecules on DCs was also investigated. Although treatment with NDP-MSH did not alter the expression of CD83 and major histocompatibility complex class I and II, the surface expression of CD86 (B7.2), intercellular adhesion molecule (ICAM-1/CD54) and CD1a was reduced. In summary, our data indicate that NDP-MSH inhibits the functional activity of DCs, possibly by down-regulating antigen-presenting and adhesion molecules and that these events may be mediated via the extracellular signal-regulated kinase 1 and 2 pathway.

The effect of allogeneic in vitro stimulation and in vivo immunization on memory CD4(+) T-cell APOBEC3G expression and HIV-1 infectivity

Allogeneic immunity is one of the most potent natural immune responses. APOBEC3G (A3G) is an intracellular anti-viral factor that deaminates cytidine to uridine. Allogeneic stimulation of human CD4(+) T cells in vitro upregulated A3G mRNA and a significant correlation was found between the mixed leukocyte reaction and A3G mRNA. The mechanism of upregulation of A3G mRNA involves interaction between HLA on DC and TCR of CD4(+) T cells, which is ZAP70 and downstream ERK phosphokinase signalling dependent and induces CD40L and A3G mRNA expression in CD4(+) T cells. Alloimmune-induced A3G was found to be significantly increased in CD45RA(-), CCR5(+) and CD45RA(-)CCR7(-) subsets of effector memory T cells. In vivo studies of women alloimmunized with their partners' PBMC also showed a significant increase in A3G protein in CD4(+) T cells, CD45RO(+) memory and CCR7(-) effector memory T cells. The functional effect of allostimulation upregulating A3G mRNA was demonstrated by a significant decrease in in vitro infectivity, using GFP-labelled pseudovirus and confirmed by a decrease in HIV-1 (BaL) infection of primary CD4(+) T cells. The results suggest that alloimmunization offers an alternative or complementary strategy in inducing an innate anti-viral factor that inhibits HIV-1 infection.

Mucosal immunization in macaques upregulates the innate APOBEC 3G anti-viral factor in CD4(+) memory T cells

APOBEC3G is an innate intracellular anti-viral factor which deaminates retroviral cytidine to uridine. In vivo studies of APOBEC3G (A3G) were carried out in rhesus macaques, following mucosal immunization with SIV antigens and CCR5 peptides, linked to the 70kDa heat shock protein. A progressive increase in A3G mRNA was elicited in PBMC after each immunization (p<0.0002 to p< or =0.02), which was maintained for at least 17 weeks. Analysis of memory T cells showed a significant increase in A3G mRNA and protein in CD4(+)CCR5(+) memory T cells in circulating (p=0.0001), splenic (p=0.0001), iliac lymph nodes (p=0.002) and rectal (p=0.01) cells of the immunized compared with unimmunized macaques. Mucosal challenge with SIVmac 251 showed a significant increase in A3G mRNA in the CD4(+)CCR5(+) circulating cells (p<0.01) and the draining iliac lymph node cells (p<0.05) in the immunized uninfected macaques, consistent with a protective effect exerted by A3G. The results suggest that mucosal immunization in a non-human primate can induce features of a memory response to an innate anti-viral factor in CCR5(+)CD4(+) memory and CD4(+)CD95(+)CCR7(-) effector memory T cells.

VISA

To gain insight into today's large data resources, data mining extracts interesting patterns. To generate knowledge from patterns and benefit from human cognitive abilities, meaningful visualization of patterns are crucial. Clustering is a data mining technique that aims at grouping data to patterns based on mutual (dis)similarity. For high dimensional data, subspace clustering searches patterns in any subspace of the attributes as patterns are typically obscured by many irrelevant attributes in the full space. For visual analysis of subspace clusters, their comparability has to be ensured. Existing subspace clustering approaches, however, lack interactive visualization and show bias with respect to the dimensionality of subspaces.

In this work, dimensionality unbiased subspace clustering and a novel distance function for subspace clusters are proposed. We suggest two visualization techniques that allow users to browse the entire subspace clustering, to zoom into individual objects, and to analyze subspace cluster characteristics in-depth. Bracketing of different parameter settings enable users to immediately see the effect of parameters on their data and hence to choose the best clustering result for further analysis. Usage of user analysis for feedback to the subspace clustering algorithm directly improves the subspace clustering. We demonstrate our visualization techniques on real world data and confirm results through additional accuracy measurements and comparison with existing subspace clustering algorithms.

Extended query refinement for medical image retrieval

The impact of image pattern recognition on accessing large databases of medical images has recently been explored, and content-based image retrieval (CBIR) in medical applications (IRMA) is researched. At the present, however, the impact of image retrieval on diagnosis is limited, and practical applications are scarce. One reason is the lack of suitable mechanisms for query refinement, in particular, the ability to (1) restore previous session states, (2) combine individual queries by Boolean operators, and (3) provide continuous-valued query refinement. This paper presents a powerful user interface for CBIR that provides all three mechanisms for extended query refinement. The various mechanisms of man-machine interaction during a retrieval session are grouped into four classes: (1) output modules, (2) parameter modules, (3) transaction modules, and (4) process modules, all of which are controlled by a detailed query logging. The query logging is linked to a relational database. Nested loops for interaction provide a maximum of flexibility within a minimum of complexity, as the entire data flow is still controlled within a single Web page. Our approach is implemented to support various modalities, orientations, and body regions using global features that model gray scale, texture, structure, and global shape characteristics. The resulting extended query refinement has a significant impact for medical CBIR applications.

Evidence for reduced B-cell progenitors in early (low-risk) myelodysplastic syndrome

Early, low-risk International Prognostic Scoring System (IPSS) myelodysplastic syndrome (MDS) is a heterogeneous disorder where the molecular and cellular hematopoietic defects are poorly understood. To gain insight into this condition, we analyzed gene expression profiles of marrow CD34+ progenitor cells from normal-karyotype, low-blast-count MDS patients, age-matched controls, and patients with non-MDS anemia. Given the heterogeneity of early MDS, a surprisingly consistent finding was decreased expression of B-cell lineage-affiliated genes in MDS patients compared with healthy controls and 3 of 5 samples with non-MDS anemia. Both patients with non-MDS anemia with reduced B-cell gene expression were on chemotherapy. In 25 of 27 of the original samples and 9 further MDS samples, Taqman real-time polymerase chain reaction (PCR) confirmed these data. Flow cytometry on unfractionated marrow from independent samples also demonstrated reduced B-cell progenitors in MDS patients compared with healthy controls. These novel findings suggest a common perturbation in early MDS hematopoiesis. They also provide the rationale for a larger study to evaluate the diagnostic utility of reduced B-cell progenitor number as a diagnostic biomarker of early low-risk MDS, which can pose a diagnostic challenge.

Molecular signatures of self-renewal, differentiation, and lineage choice in multipotential hemopoietic progenitor cells in vitro

The molecular mechanisms governing self-renewal, differentiation, and lineage specification remain unknown. Transcriptional profiling is likely to provide insight into these processes but, as yet, has been confined to "static" molecular profiles of stem and progenitors cells. We now provide a comprehensive, statistically robust, and "dynamic" analysis of multipotent hemopoietic progenitor cells undergoing self-renewal in response to interleukin-3 (IL-3) and multilineage differentiation in response to lineage-affiliated cytokines. Cells undergoing IL-3-dependent proliferative self-renewal displayed striking complexity, including expression of genes associated with different lineage programs, suggesting a highly responsive compartment poised to rapidly execute intrinsically or extrinsically initiated cell fate decisions. A remarkable general feature of early differentiation was a resolution of complexity through the downregulation of gene expression. Although effector genes characteristic of mature cells were upregulated late, coincident with morphological changes, lineage-specific changes in gene expression were observed prior to this, identifying genes which may provide early harbingers of unilineage commitment. Of particular interest were genes that displayed differential behavior irrespective of the lineage elaborated, many of which were rapidly downregulated within 4 to 8 h after exposure to a differentiation cue. These are likely to include genes important in self-renewal, the maintenance of multipotentiality, or the negative regulation of differentiation per se.