Lactadherin Inhibits Secretory Phospholipase A2 Activity on Pre-Apoptotic Leukemia Cells

Secretory phospholipase A2 (sPLA2) is a critical component of insect and snake venoms and is secreted by mammalian leukocytes during inflammation. Elevated secretory PLA2 concentrations are associated with autoimmune diseases and septic shock. Many sPLA2’s do not bind to plasma membranes of quiescent cells but bind and digest phospholipids on the membranes of stimulated or apoptotic cells. The capacity of these phospholipases to digest membranes of stimulated or apoptotic cells correlates to the exposure of phosphatidylserine. In the present study, the ability of the phosphatidyl-L-serine-binding protein, lactadherin to inhibit phospholipase enzyme activity has been assessed. Inhibition of human secretory phospholipase A2-V on phospholipid vesicles exceeded 90%, whereas inhibition of Naja mossambica sPLA2 plateaued at 50–60%. Lactadherin inhibited 45% of activity of Naja mossambica sPLA2 and >70% of human secretory phospholipase A2-V on the membranes of human NB4 leukemia cells treated with calcium ionophore A23187. The data indicate that lactadherin may decrease inflammation by inhibiting sPLA2

Correction to: Rewiring of glucose metabolism defines trained immunity induced by oxidized low-density lipoprotein

The correct name of the 17th Author is presented in this paper. In the paragraph “Metabolic analysis” of the Method section “an XFp Analyzer” should be changed to “an XFe96 Analyzer”.</p

The role of Toll-like receptor 10 in modulation of trained immunity

Toll-like receptor 10 (TLR10) is the only member of the human Toll-like receptor family with an inhibitory function on the induction of innate immune responses and inflammation. However, its role in the modulation of trained immunity (innate immune memory) is unknown. In the present study, we assessed whether TLR10 modulates the induction of trained immunity induced by beta-glucan or bacillus Calmette-Guerin (BCG). Interleukin 10 receptor antagonist production was increased upon activation of TLR10 ex vivo after BCG vaccination, and TLR10 protein expression on monocytes was increased after BCG vaccination, whereas anti-TLR10 antibodies did not significantly modulate beta-glucan or BCG-induced trained immunity in vitro. A known immunomodulatory TLR10 missense single-nucleotide polymorphism (rs11096957) influenced trained immunity responses by beta-glucan or BCG in vitro. However, the in vivo induction of trained immunity by BCG vaccination was not influenced by TLR10 polymorphisms. In conclusion, TLR10 has a limited, non-essential impact on the induction of trained immunity in humans

Particulate matter exposure during pregnancy is associated with birth weight, but not gestational age, 1962-1992: a cohort study

<p>Abstract</p> <p>Background</p> <p>Exposure to air pollutants is suggested to adversely affect fetal growth, but the evidence remains inconsistent in relation to specific outcomes and exposure windows.</p> <p>Methods</p> <p>Using birth records from the two major maternity hospitals in Newcastle upon Tyne in northern England between 1961 and 1992, we constructed a database of all births to mothers resident within the city. Weekly black smoke exposure levels from routine data recorded at 20 air pollution monitoring stations were obtained and individual exposures were estimated via a two-stage modeling strategy, incorporating temporally and spatially varying covariates. Regression analyses, including 88,679 births, assessed potential associations between exposure to black smoke and birth weight, gestational age and birth weight standardized for gestational age and sex.</p> <p>Results</p> <p>Significant associations were seen between black smoke and both standardized and unstandardized birth weight, but not for gestational age when adjusted for potential confounders. Not all associations were linear. For an increase in whole pregnancy black smoke exposure, from the 1^st(7.4 μg/m³) to the 25^th(17.2 μg/m³), 50^th(33.8 μg/m³), 75^th(108.3 μg/m³), and 90^th(180.8 μg/m³) percentiles, the adjusted estimated decreases in birth weight were 33 g (SE 1.05), 62 g (1.63), 98 g (2.26) and 109 g (2.44) respectively. A significant interaction was observed between socio-economic deprivation and black smoke on both standardized and unstandardized birth weight with increasing effects of black smoke in reducing birth weight seen with increasing socio-economic disadvantage.</p> <p>Conclusions</p> <p>The findings of this study progress the hypothesis that the association between black smoke and birth weight may be mediated through intrauterine growth restriction. The associations between black smoke and birth weight were of the same order of magnitude as those reported for passive smoking. These findings add to the growing evidence of the harmful effects of air pollution on birth outcomes.</p

Microparticle Phosphatidylserine Mediates Coagulation: Involvement in Tumor Progression and Metastasis

Tumor progression and cancer metastasis has been linked to the release of microparticles (MPs), which are shed upon cell activation or apoptosis and display parental cell antigens, phospholipids such as phosphatidylserine (PS), and nucleic acids on their external surfaces. In this review, we highlight the biogenesis of MPs as well as the pathophysiological processes of PS externalization and its involvement in coagulation activation. We review the available evidence, suggesting that coagulation factors (mainly tissue factor, thrombin, and fibrin) assist in multiple steps of tumor dissemination, including epithelial–mesenchymal transition, extracellular matrix remodeling, immune escape, and tumor angiogenesis to support the formation of the pre-metastatic niche. Platelets are not just bystander cells in circulation but are functional players in primary tumor growth and metastasis. Tumor-induced platelet aggregation protects circulating tumor cells (CTCs) from the blood flow shear forces and immune cell attack while also promoting the binding of CTCs to endothelial cells and extravasation, which activates tumor invasion and sustains metastasis. Finally, in terms of therapy, lactadherin can inhibit coagulation by competing effectively with coagulation factors for PS binding sites and may similarly delay tumor progression. Furthermore, we also investigate the therapeutic potential of coagulation factor inhibitors within the context of cancer treatment. The development of multiple therapies targeting platelet activation and platelet–tumor cell interactions may not only reduce the lethal consequences of thrombosis but also impede tumor growth and spread

Mechanical reconfiguration mediates swallowing and rejection in Aplysia californica

Muscular hydrostats, such as tongues, trunks or tentacles, have fewer constraints on their degrees of freedom than musculoskeletal systems, so changes in a structure&apos;s shape may alter the positions and lengths of other components (i.e., induce mechanical reconfiguration) . We studied mechanical reconfiguration during rejection and swallowing in the marine mollusk Aplysia californica. During rejection, inedible material is pushed out of an animal&apos;s buccal cavity. The grasper (radula/ odontophore) closes on inedible material, and then a posterior muscle, I2, pushes the grasper toward the jaws (protracts it). After the material is released, an anterior muscle complex (the I1/I3/jaw complex) pushes the grasper toward the esophagus (retracts it). During swallowing, the grasper is protracted open, and then retracts closed, pulling in food. Grasper closure changes its shape. Magnetic resonance images show that grasper closure lengthens I2. A kinetic model quantified the changes in the ability of I2 and I1/I3 to exert force as grasper shape changed. Grasper closure increases I2&apos;s ability to protract during rejection, and increases I1/I3&apos;s ability to retract during swallowing. Motor neurons controlling radular closure may therefore a#ect the behavioral outputs of I2&apos;s and I1/I3&apos;s motor neurons. Thus, motor neurons may modulate the outputs of other motor neurons through mechanical reconfiguration

Inhibitory activity of lactadherin toward sPLA₂’s on human leukemia cells.

<p>(<b>A</b>) NB4 cells were treated with 6 µM A23187 for 10 minutes at 22°C prior to addition of phospholipases. This treatment resulted in 61.6% pre-apoptotic cells. Phospholipase activity was detected as release of free fatty acids using the ADIFAB reagent. Each curve was run as a set in quadruplicates using a single mixture of ADIFAB and PLA₂. Curves were run in separate sets. The initial reaction rates for nmPLA₂ and hsPLA₂-V were calculated by linear regression to the first 5 and 15 seconds respectively, were r² = 0.85–0.95. (<b>B</b>) 0.06 U/ml nmPLA₂ phospholipase activity on quiescent, stressed cells and stressed with 300 nM lactadherin were measured. Lactadherin was added to the cell mix immediately before adding the ionophore, proceeding with 10 minute incubation. Control curves from similar treated cells without added enzyme were subtracted as background and extrapolated Y values at injection point found using Eq. 3. Sum curves of quadruplicate sets are displayed (<b>C</b>) The experiment was repeated as in panel B using 0.06 U/ml hsPLA₂-V. The initial reaction rate was calculated the same way as panel B. See panel <b>4D</b> and <b>4E</b> for quadruplicate results of nmPLA₂ and hsPLA₂-V respectively, SD displayed with *denoting p<0.05 and **denoting p<0.001. To discount any adverse interactions between A23187 and lactadherin, cells were stressed using 40 µM etoposide as described in materials and methods. As seen in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077143#pone-0077143-g004" target="_blank">Figure <b>4F</b></a>, inhibition of hsPLA₂-V to near quiescent levels by addition of 300 nM lactadherin was observed, producing very similar inhibition ratios as found when using the quick, A23187 and lactadherin co-incubation protocol. Statistical significance using a one-tailed T-test assuming unequal variance showed a significance of p<0.03.</p

Relationship between PLA₂ concentration, phospholipid concentration, and phospholipase activity.

<p>(<b>A</b>) Varying concentrations of sonicated vesicles of composition PS:PE:PC:bbPC 4∶20:75∶1 were allowed to equilibrate at 4°C for 5 minutes before adding 0.125 U/ml nmPLA₂. The resulting curve replicates were standardized and fitted to a two-phase exponential association model (Eq. 1) and solved for global rate constants (fitted curves). (<b>B</b>) Total Y_max obtained from fitted curves was plotted against phospholipid concentrations and fitted to a Michaelis-Menten equation. (<b>C</b>) The initial reaction rate was obtained from the original datasets using linear regression from 0–5 seconds and plotted against phospholipid concentration. A Michaelis-Menten equation was fitted to the data and of high fit quality. The results indicate a saturable dose-response relationship. Experiments at each phospholipid or phospholipase concentration were performed a minimum of two times, and values averaged.</p

Cleavage of fluorescent phospholipid by nmPLA₂ and inhibition by lactadherin.

<p>Sonicated phospholipid vesicles, 10 µM, of composition PS:PE:PC:bbPC 4∶20:75∶1 were pre-incubated for 15 minutes in PBS, pH 7.2 at 22°C with, or without, pure lipid-free bovine lactadherin before addition to a quartz cuvette of 3×3×45 mm. Vesicles were incubated for 5 minutes at 4°C in the Peltier-thermostatted sample chamber of the fluorometer before adding nmPLA₂ to a final concentration of 0.06 U/ml. Reaction curves are normalized to baseline fluorescence intensity before addition of phospholipase as per Eq. 2.</p