CLEC5A (MDL-1) is a novel PU.1 transcriptional target during myeloid differentiation

C-type lectin domain family 5, member A (CLEC5A), also known as myeloid DNAX activation protein 12 (DAP12)-associating lectin-1 (MDL-1), is a cell surface receptor strongly associated with the activation and differentiation of myeloid cells. CLEC5A associates with its adaptor protein DAP12 to activate a signaling cascade resulting in activation of downstream kinases in inflammatory responses. Currently, little is known about the transcriptional regulation of CLEC5A. We identified CLEC5A as one of the most highly induced genes in a microarray gene profiling experiment of PU.1 restored myeloid PU.1-null cells. We further report that CLEC5A expression is significantly reduced in several myeloid differentiation models upon PU.1 inhibition during monocyte/macrophage or granulocyte differentiation. In addition, CLEC5A mRNA expression was significantly lower in primary acute myeloid leukemia (AML) patient samples than in macrophages and granulocytes from healthy donors. Moreover, we found activation of a CLEC5A promoter reporter by PU.1 as well as in vivo binding of PU.1 to the CLEC5A promoter. Our findings indicate that CLEC5A expression in monocyte/macrophage and granulocytes is regulated by PU.1.

One hundred fascia-sparing myocutaneous rectus abdominis flaps: An update

Major efforts have been undertaken to reduce donor-site morbidity after abdominal flaps, which eventually culminated in the introduction of the deep inferior epigastric perforator (DIEP) flap. However, due to anatomical variations (absence of dominant perforators) and the risk of ischaemic complications, the selection of patients qualifying for a DIEP flap is limited. Furthermore, DIEP flaps can only be used as free flaps. We present our long-term experience with a dissection technique of rectus abdominis myocutaneous (RAM) flaps that was developed to circumvent these drawbacks. The dissection is characterised by preventing to sacrifice any perforators nourishing the flap and by fully preserving the anterior rectus sheath, but not the muscle. The study comprises a consecutive series of prospectively assessed patients, treated between February 2000 and April 2008. A total of 100 fascia-sparing RAM flaps were operated on 97 patients (age 22-84 years, median 64 years). Free flaps were mainly used for breast reconstruction (47 flaps/24 patients), and cranially (34) or caudally (19) pedicled flaps for soft-tissue coverage after sternectomy, urogenital tumour resection or rectum amputation. Eighty patients had a total of 213 risk factors, such as cardiovascular diseases, obesity, hyperlipidaemia, diabetes mellitus, smoking or steroid medication. Partial tissue loss (skin or fat necrosis) occurred in 13 flaps, out of which seven required surgical revision. The ischaemic complications were evenly distributed between the patient subsets. At a follow-up of 2-89 months (median 20 months), one patient showed a flap harvest-related abdominal bulge after bilateral-free transverse rectus abdominis myocutaneous (TRAM) flap. We conclude that the present dissection technique provides maximal perforator-related perfusion and minimal donor-site morbidity even in pedicled flaps and high-risk patients. In free flaps, it may, therefore, be recommended as an alternative to the DIEP flap.

Inhibition of direct and indirect TLR-mediated activation of human NK cells by low molecular weight dextran sulfate

NK cells express toll-like receptors (TLR) that recognize conserved pathogen or damage associated molecular patterns and play a fundamental role in innate immunity. Low molecular weight dextran sulfate (DXS), known to inhibit the complement system, has recently been reported by us to inhibit TLR4-induced maturation of human monocyte-derived dendritic cells (MoDC). In this study, we investigated the capability of DXS to interfere with human NK cell activation triggered directly by TLR2 agonists or indirectly by supernatants of TLR4-activated MoDC. Both TLR2 agonists and supernatants of TLR4-activated MoDC activated NK cells phenotypically, as demonstrated by the analysis of NK cell activation markers (CD56, CD25, CD69, NKp30, NKp44, NKp46, DNAM-1 and NKG2D), and functionally as shown by increased NK cell degranulation (CD107a surface expression) and IFN-gamma secretion. DXS prevented the up-regulation of NK cell activation markers triggered by TLR2 ligands or supernatants of TLR4-activated MoDC and dose-dependently abrogated NK cell degranulation and IFN-gamma secretion. In summary our results suggest that DXS may be a useful reagent to inhibit the direct and indirect TLR-mediated activation of NK cells.

Current status of drug-eluting stents

First-generation drug-eluting stents (DES) with controlled release of sirolimus or paclitaxel from durable polymers compared with bare-metal stents have been consistently shown to reduce the risk of repeat revascularization procedures due to restenosis. The superior efficacy was found across a wide range of patients and lesion subsets and persisted up to 5 years whereas similar outcomes have been observed in terms of death and myocardial infarction. Newer generation DES have been developed with the goal to further improve upon the safety profile of first-generation DES while maintaining efficacy. These platforms include DES with improved and more biocompatible durable polymers, DES using bioabsorbable polymers for drug release, DES with polymer-free drug release, and fully bioabsorbable DES. Newer generation DES with durable polymers such as zotarolimus-eluting or everolimus-eluting XIENCE V stents have been directly compared with first-generation DES. Most recent results of large scale clinical trials are encouraging in terms of similar or increased efficacy while improving safety by reducing the rates of myocardial infarctions and stent thrombosis. DES using biodegradable polymers for drug release represent the next technological modification and preliminary results are favorable and demonstrate similar angiographic and clinical efficacy as first-generation DES, but only longer term follow-up and investigation in larger patient cohorts will determine whether their use is associated with improved long-term safety. Fully bioabsorbable stents represent another innovative approach. Whether this innovative concept will enter into clinical routine remains yet to be determined.

Innate-like control of human iNKT cell autoreactivity via the hypervariable CDR3beta loop

Invariant Natural Killer T cells (iNKT) are a versatile lymphocyte subset with important roles in both host defense and immunological tolerance. They express a highly conserved TCR which mediates recognition of the non-polymorphic, lipid-binding molecule CD1d. The structure of human iNKT TCRs is unique in that only one of the six complementarity determining region (CDR) loops, CDR3beta, is hypervariable. The role of this loop for iNKT biology has been controversial, and it is unresolved whether it contributes to iNKT TCR:CD1d binding or antigen selectivity. On the one hand, the CDR3beta loop is dispensable for iNKT TCR binding to CD1d molecules presenting the xenobiotic alpha-galactosylceramide ligand KRN7000, which elicits a strong functional response from mouse and human iNKT cells. However, a role for CDR3beta in the recognition of CD1d molecules presenting less potent ligands, such as self-lipids, is suggested by the clonal distribution of iNKT autoreactivity. We demonstrate that the human iNKT repertoire comprises subsets of greatly differing TCR affinity to CD1d, and that these differences relate to their autoreactive functions. These functionally different iNKT subsets segregate in their ability to bind CD1d-tetramers loaded with the partial agonist alpha-linked glycolipid antigen OCH and structurally different endogenous beta-glycosylceramides. Using surface plasmon resonance with recombinant iNKT TCRs and different ligand-CD1d complexes, we demonstrate that the CDR3beta sequence strongly impacts on the iNKT TCR affinity to CD1d, independent of the loaded CD1d ligand. Collectively our data reveal a crucial role for CDR3beta for the function of human iNKT cells by tuning the overall affinity of the iNKT TCR to CD1d. This mechanism is relatively independent of the bound CD1d ligand and thus forms the basis of an inherent, CDR3beta dependent functional hierarchy of human iNKT cells.

Attenuation of cerebrospinal fluid inflammation by the nonbacteriolytic antibiotic daptomycin versus that by ceftriaxone in experimental pneumococcal meningitis

Antibiotic-induced bacteriolysis exacerbates inflammation and brain damage in bacterial meningitis. Here the quality and temporal kinetics of cerebrospinal fluid (CSF) inflammation were assessed in an infant rat pneumococcal meningitis model for the nonbacteriolytic antibiotic daptomycin versus ceftriaxone. Daptomycin led to lower CSF concentrations of interleukin 1beta (IL-1beta), IL-10, IL-18, monocyte chemoattractant protein 1 (MCP-1), and macrophage inflammatory protein 1 alpha (MIP-1alpha) (P < 0.05). In experimental pneumococcal meningitis, daptomycin treatment resulted in more rapid bacterial killing, lower CSF inflammation, and less brain damage than ceftriaxone treatment.