IL-15 and macrophage secretory factors facilitate immune activation of neonatal natural killer cells by lipoteichoic acid

Neonates possess a relatively “naive”, yet inducible immune system. Our hypothesis is that upon strategic antigen exposure, cytokine priming and sensitization by accessory cells, natural killer (NK) cells could be activated to become a functional phenotype. We investigated the in vitro stimulation of cord blood (CB) and adult NK cells upon challenge with lipoteichoic acid (LTA), interleukin (IL)-15 and LTA-primed autologous macrophage-conditioned medium, using CD107a and CD69 phenotypes as indicators of activation. We also examined response of CB macrophages to LTA, in terms of P44/42 extracellular signal-regulated kinases (ERK1/2) activation and cytokine secretion. LTA significantly induced secretion of inflammatory cytokines tumor necrotic factor (TNF)-α, IL-6, IL-12 and activated the upstream signal of ERK1/2 phosphorylation in neonatal macrophages. The magnitude of responses to stimulation differed between neonatal and adult NK cells. Co-stimulation with IL-15 was critical for expansion of the CD69 and CD107a NK subpopulations in both neonatal and adult cells, upon a LTA challenge. NK cell activation could be enhanced by LTA-primed autologous macrophages through secretory factors. Our results indicated that neonatal macrophages and NK cells can evoke immunologic responses to a Gram-positive bacterial antigen. The combinatory priming strategy is relevant for development of novel protocols, such as IL-15 treatment, to compensate for the immaturity of the innate immune system in newborns against bacterial infections.     

Computational Fluid Dynamics Modeling of Symptomatic Intracranial Atherosclerosis May Predict Risk of Stroke Recurrence

Background

Patients with symptomatic intracranial atherosclerosis (ICAS) of ≥70% luminal stenosis are at high risk of stroke recurrence. We aimed to evaluate the relationships between hemodynamics of ICAS revealed by computational fluid dynamics (CFD) models and risk of stroke recurrence in this patient subset.

Methods

Patients with a symptomatic ICAS lesion of 70–99% luminal stenosis were screened and enrolled in this study. CFD models were reconstructed based on baseline computed tomographic angiography (CTA) source images, to reveal hemodynamics of the qualifying symptomatic ICAS lesions. Change of pressures across a lesion was represented by the ratio of post- and pre-stenotic pressures. Change of shear strain rates (SSR) across a lesion was represented by the ratio of SSRs at the stenotic throat and proximal normal vessel segment, similar for the change of flow velocities. Patients were followed up for 1 year.

Results

Overall, 32 patients (median age 65; 59.4% males) were recruited. The median pressure, SSR and velocity ratios for the ICAS lesions were 0.40 (−2.46–0.79), 4.5 (2.2–20.6), and 7.4 (5.2–12.5), respectively. SSR ratio (hazard ratio [HR] 1.027; 95% confidence interval [CI], 1.004–1.051; P = 0.023) and velocity ratio (HR 1.029; 95% CI, 1.002–1.056; P = 0.035) were significantly related to recurrent territorial ischemic stroke within 1 year by univariate Cox regression, respectively with the c-statistics of 0.776 (95% CI, 0.594–0.903; P = 0.014) and 0.776 (95% CI, 0.594–0.903; P = 0.002) in receiver operating characteristic analysis.

Conclusions

Hemodynamics of ICAS on CFD models reconstructed from routinely obtained CTA images may predict subsequent stroke recurrence in patients with a symptomatic ICAS lesion of 70–99% luminal stenosis.     

Expression of ORAI1, a Plasma Membrane Resident Subunit of the CRAC Channel,in Rodent and Non-rodent Species

We determined the expression of ORAI1 protein in rodent and non-rodent tissues using a monoclonal antibody directed against an extracellular loop of the protein. Previous reports using antibodies directed at the C-terminus of ORAI1 have not detected central nervous system (CNS) expression. Our results demonstrate broad tissue expression that includes the CNS using a unique monoclonal antibody specific to an extracellular loop of ORAI1. In addition, we present in situ hybridization (ISH) results using a probe within the middle of the mouse coding region showing CNS expression of Orai1 RNA. We contrast the patterns of rodent and human tissue expression and conclude that rodents have similar expression of ORAI1 in most tissue types when compared to primates, with an important exception being the male reproductive system, where human-specific expression is observed.     

Regulation of Induced Pluripotent Stem (iPS) Cell Induction by Wnt/β-Catenin Signaling

Wnt signaling has been implicated in promoting somatic cell reprogramming. However, its molecular mechanisms remain unknown. Here we report that Wnt/β-catenin enhances iPSCs induction at the early stage of reprogramming. The augmented reprogramming induced by β-catenin is not due to increased total cell population or activation of c-Myc. In addition, β-catenin interacts with reprogramming factors Klf4, Oct4, and Sox2, further enhancing expression of pluripotency circuitry genes. These studies reveal novel mechanisms underlying the regulation of reprogramming somatic cells to pluripotency by Wnt/β-catenin signaling.     

An extracellular retinol-binding glycoprotein in the rat eye—characterization,localization and biosynthesis

We have identified and partially purified interstitial retinol-binding protein (IRBP) from the subretinal space of the rat. It appeared to be glycosylated. Its apparent mol. wt was 270,000 by gel-filtration and 144,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Rat IRBP cross-reacted with anti-bovine IRBP sheep and rabbit sera, bound all-trans-[15-³H] retinol and was bound by concanavalin A. IRBP was not detected in the cytosols of the neural retina or retinal pigment epithelium and choroid. This distribution was confirmed by immunocytochemistry using a fluorescence-labeled second antibody. Immunospecific fluorescence was most intense in the interphotoreceptor matrix in a 6.5 μm band adjacent to the retinal pigment epithelium. It was less intense over the remainder of the rod outer segment layer and was comparatively faint over the inner segment region. Its occurrence in the interstitial space between the photoreceptors and retinal pigment epithelium coupled with the fact it bound all-trans-[15-³H] retinol supports the concept that it may be implicated in the transport of retinoids between the retina and the retinal pigment epithelium during the visual cycle. When incubated with [³H]leucine or [³H]glucosamine, isolated retinas (but not retinal pigment epithelium and choroid) secreted labeled IRBP into the medium. This suggests that the retina plays a role in regulating the amount of IRBP in the subretinal space.     

Isolation and evaluation of kaempferol glycosides from the fern Neocheiropteris palmatopedata

Kaempferol glycosides, named palmatosides A (1), B (2) and C (3), together with three known kaempferol glycosides, multiflorins A (4) and B (5), and afzelin (6), were isolated from the roots of the fern Neocheiropteris palmatopedata. Palmatosides A (1) and B (2) each possessed an unusual sugar moiety containing a 4,4-dimethyl-3-oxo-butoxy substituent group. The isolated compounds were evaluated for their cancer chemopreventive potential based on their ability to inhibit tumor necrosis factor alpha (TNF-α)-induced NF-κB activity, nitric oxide (NO) production, aromatase, quinone reductase 2 (QR2) and COX-1/-2 activities. Palmatosides B (2) and C (3) inhibited TNF-α-induced NF-κB activity with IC₅₀ values of 15.7 and 24.1 μM, respectively; multiflorin A (4) inhibited aromatase enzyme with an IC₅₀ value of 15.5 μM; afzelin (6) showed 68.3% inhibition against QR2 at a concentration of 11.5 μg/ml; palmatoside A (1) showed 52% inhibition against COX-1 enzyme at a concentration of 10 μg/ml; and multiflorin B (5) showed 52% inhibition against nitric oxide production at a concentration of 20 μg/ml. In addition, compounds 3–6 were shown to bind QR2 enzyme using LC–MS ultrafiltration binding assay.     

Upward cascading effects of nutrients: shifts in a benthic microalgal community and a negative herbivore response

We evaluated the effects of nutrient addition on interactions between the benthic microalgal community and a dominant herbivorous gastropod, Cerithidea californica (California horn snail), on tidal flats in Mugu Lagoon, southern California, USA. We crossed snail and nutrient (N and P) addition treatments in enclosures on two tidal flats varying from 71 to 92% sand content in a temporally replicated experiment (summer 2000, fall 2000, spring 2001). Diatom biomass increased slightly (~30%) in response to nutrient treatments but was not affected by snails. Blooms of cyanobacteria (up to 200%) and purple sulfur bacteria (up to 400%) occurred in response to nutrient enrichment, particularly in the sandier site, but only cyanobacterial biomass decreased in response to snail grazing. Snail mortality was 2–5 times higher in response to nutrient addition, especially in the sandier site, corresponding to a relative increase in cyanobacterial biomass. Nutrient-related snail mortality occurred only in the spring and summer, when the snails were most actively feeding on the microalgal community. Inactive snails in the fall showed no response to nutrient-induced cyanobacterial growths. This study demonstrated strongly negative upward cascading effects of nutrient enrichment through the food chain. The strength of this upward cascade was closely linked to sediment type and microalgal community composition.     

Identification of the erythropoietin receptors of erythroleukemic cells

Erythropoietin (epo) is the physiologic regulator of red blood cell development. We have demonstrated the presence of epo receptors on two erythroleukemia cell lines, IW32 and IW201. IW32 produces epo constitutively while IW201 is a nonproducing cell line. Neither cell lines respond to epo to differentiate. In this study, we have shown that these cells bound 125I-epo specifically. Binding could be displaced by the presence of unlabeled epo but not by insulin or epidermal growth factor. In contrast to that found in epo responsive cells isolated from Friend virus infected mouse spleen, which were reported to contain both "high" and "low" affinity receptors, our finding indicated only a single class of "low" affinity receptors with apparent dissociation constants of 1.7 nM and 2.0 nM for IW32 and IW201 cell lines, respectively. It is suggested that the absence of "high" affinity receptors may account for the lack of responsiveness of these cells to epo.