Properties and functions of lactosylceramide from mouse neutrophils.

Lactosylceramide (LacCer), which is essential for many cellular processes, is highly expressed on the plasma membranes of human neutrophils and mediates innate immune functions. Less is known, however, about the properties and biological functions of LacCer in mouse neutrophils. This study therefore analyzed the properties of mouse neutrophil LacCer.

Pseudomonas-derived ceramidase induces production of inflammatory mediators from human keratinocytes via sphingosine-1-phosphate.

Ceramide is important for water retention and permeability barrier functions in the stratum corneum, and plays a key role in the pathogenesis of atopic dermatitis (AD). A Pseudomonas aeruginosa-derived neutral ceramidase (PaCDase) isolated from a patient with AD was shown to effectively degrade ceramide in the presence of Staphylococcus aureus-derived lipids or neutral detergents. However, the effect of ceramide metabolites on the functions of differentiating keratinocytes is poorly understood.

Anti-neutral glycolipid antibodies in encephalomyeloradiculoneuropathy.

Objective: The aim of this study was to review 4 patients with encephalomyeloradiculoneuropathy (EMRN) and assess for autoantibodies against neutral glycolipids.

Methods: We studied the progression of clinical, radiologic, neurophysiologic, and CSF findings, as well as anti-neutral glycolipid antibodies in sera.

Results: All patients developed acute or subacute motor weakness and impaired consciousness.

Cytotoxicity and glycan-binding properties of an 18 kDa lectin isolated from the marine sponge Halichondria okadai.

A divalent cation-independent lectin-HOL-18, with cytotoxic activity against leukemia cells, was purified from a demosponge, Halichondria okadai. HOL-18 is a 72 kDa tetrameric lectin that consists of four non-covalently bonded 18 kDa subunits. Hemagglutination activity of the lectin was strongly inhibited by chitotriose (GlcNAcβ1-4GlcNAcβ1-4GlcNAc), fetuin and mucins from porcine stomach and bovine submaxillary gland.

Di-(2-ethylhexyl) phthalate induces production of inflammatory molecules in human macrophages.

Objective And Design: To investigate whether di-(2-ethylhexyl) phthalate (DEHP) affects the production of inflammatory cytokines by human macrophages.

Materials And Methods: Differentiated macrophage-like THP-1 cells were exposed to 200 μM DEHP for 3 h, followed by incubation in the presence or absence of opsonized zymosan A, and the concentrations of TNF-α, IL-1β, IL-8, and IL-6 in the culture media were determined by ELISA. DNA microarray and quantitative real-time RT-PCR analyses were performed to identify genes that showed changes in expression in response to DEHP.

Cytotoxicity and glycan-binding profile of a D-galactose-binding lectin from the eggs of a Japanese sea hare (Aplysia kurodai).

A divalent cation-independent 16 kDa D-galactose binding lectin (AKL-2) was isolated from eggs of sea hare, Aplysia kurodai. The lectin recognized D-galactose and D-galacturonic acid and had a 32 kDa dimer consisting of two disulfide-bonded 16 kDa subunits. Eighteen N-terminus amino acids were identified by Edman degradation, having unique primary structure.

Involvement of cholesterol-enriched microdomains in class A scavenger receptor-mediated responses in human macrophages.

Objective: Lipid rafts are cholesterol-enriched microdomains on cell membranes. We hypothesized that these microdomains could involve modified low-density lipoprotein (LDL) uptake.

Methods And Results: Co-localizations of cholesterol-enriched microdomains and CD204 during the uptake of acetyl LDL (AcLDL) and oxidized LDL were observed using Alexa488-labeled polyethylene glycol cholesteryl ester, which is a sensitive probe used to analyze the dynamics of cholesterol-rich lipid microdomains in living cells.

Different responses to oxidized low-density lipoproteins in human polarized macrophages.

Background: Oxidized low-density lipoprotein (oxLDL) uptake by macrophages plays an important role in foam cell formation. It has been suggested the presence of heterogeneous subsets of macrophage, such as M1 and M2, in human atherosclerotic lesions. To evaluate which types of macrophages contribute to atherogenesis, we performed cDNA microarray analysis to determine oxLDL-induced transcriptional alterations of each subset of macrophages.

Significance of glycosphingolipid fatty acid chain length on membrane microdomain-mediated signal transduction.

Lactosylceramide (LacCer), a neutral glycosphingolipid, is abundantly expressed on human neutrophils, and specifically recognizes several pathogenic microorganisms. LacCer forms membrane microdomains coupled with the Src family kinase Lyn on the plasma membrane, and ligand binding to LacCer activates Lyn, resulting in neutrophil functions. In contrast, neutrophilic differentiated HL-60 cells do not have Lyn-associated LacCer-enriched microdomains and lack LacCer-mediated functions.

Role of glycosphingolipid-enriched microdomains in innate immunity: microdomain-dependent phagocytic cell functions.

The innate immune system is the first line of defense against pathogenic microorganisms, such as bacteria, fungi, and viruses. Phagocytes, such as neutrophils and macrophages, play an important role in the innate immune system by recognizing, engulfing, and eliminating pathogens. It has been suggested that lipid membrane microdomains/rafts of phagocytes are involved in these innate immune responses, including superoxide generation, cell migration, and phagocytosis.