Skin TLR7 Triggering Promotes Accumulation of Respiratory Dendritic Cells and Natural Killer Cells

The TLR7 agonist imiquimod has been used successfully as adjuvant for skin treatment of virus-associated warts and basal cell carcinoma. The effects of skin TLR7 triggering on respiratory leukocyte populations are unknown. In a placebo-controlled experimental animal study we have used multicolour flow cytometry to systematically analyze the modulation of respiratory leukocyte subsets after skin administration of imiquimod. Compared to placebo, skin administration of imiquimod significantly increased respiratory dendritic cells (DC) and natural killer cells, whereas total respiratory leukocyte, alveolar macrophages, classical CD4+ T helper and CD8+ T killer cell numbers were not or only moderately affected. DC subpopulation analyses revealed that elevation of respiratory DC was caused by an increase of respiratory monocytic DC and CD11b(hi) DC subsets. Lymphocyte subpopulation analyses indicated a marked elevation of respiratory natural killer cells and a significant reduction of B lymphocytes. Analysis of cytokine responses of respiratory leukocytes after stimulation with Klebsiella pneumonia indicated reduced IFN-γ and TNF-α expression and increased IL-10 and IL-12p70 production after 7 day low dose skin TLR7 triggering. Additionally, respiratory NK cytotoxic activity was increased after 7d skin TLR7 triggering. In contrast, lung histology and bronchoalveolar cell counts were not affected suggesting that skin TLR7 stimulation modulated respiratory leukocyte composition without inducing overt pulmonary inflammation. These data suggest the possibility to modulate respiratory leukocyte composition and respiratory cytokine responses against pathogens like Klebsiella pneumonia through skin administration of a clinically approved TLR7 ligand. Skin administration of synthetic TLR7 ligands may represent a novel, noninvasive means to modulate respiratory immunity.     

Uptake mechanism of ApoE-modified nanoparticles on brain capillary endothelial cells as a blood-brain barrier model

Background

The blood-brain barrier (BBB) represents an insurmountable obstacle for most drugs thus obstructing an effective treatment of many brain diseases. One solution for overcoming this barrier is a transport by binding of these drugs to surface-modified nanoparticles. Especially apolipoprotein E (ApoE) appears to play a major role in the nanoparticle-mediated drug transport across the BBB. However, at present the underlying mechanism is incompletely understood.

Methodology/Principal Findings

In this study, the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells was investigated to differentiate between active and passive uptake mechanism by flow cytometry and confocal laser scanning microscopy. Furthermore, different in vitro co-incubation experiments were performed with competing ligands of the respective receptor.

Conclusions/Significance

This study confirms an active endocytotic uptake mechanism and shows the involvement of low density lipoprotein receptor family members, notably the low density lipoprotein receptor related protein, on the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells. This knowledge of the uptake mechanism of ApoE-modified nanoparticles enables future developments to rationally create very specific and effective carriers to overcome the blood-brain barrier.     

Retinal ganglion cell loss is accompanied by antibody depositions and increased levels of microglia after immunization with retinal antigens

Background

Antibodies against retinal and optic nerve antigens are detectable in glaucoma patients. Recent studies using a model of experimental autoimmune glaucoma demonstrated that immunization with certain ocular antigens causes an immun-mediated retinal ganglion cell loss in rats.

Methodology/Principal Findings

Rats immunized with a retinal ganglion cell layer homogenate (RGA) had a reduced retinal ganglion cell density on retinal flatmounts (p = 0.007) and a lower number of Brn3⁺retinal ganglion cells (p = 0.0001) after six weeks. The autoreactive antibody development against retina and optic nerve was examined throughout the study. The levels of autoreactive antibodies continuously increased up to 6 weeks (retina: p = 0.004; optic nerve: p = 0.000003). Additionally, antibody deposits were detected in the retina (p = 0.02). After 6 weeks a reactive gliosis (GFAP density: RGA: 174.7±41.9; CO: 137.6±36.8, p = 0.0006; %GFAP⁺ area: RGA: 8.5±3.4; CO: 5.9±3.6, p = 0.006) as well as elevated level of Iba1⁺ microglia cells (p = 0.003) was observed in retinas of RGA animals.

Conclusions/Significance

Our findings suggest that these antibodies play a substantial role in mechanisms leading to retinal ganglion cell death. This seems to lead to glia cell activation as well as the invasion of microglia, which might be associated with debris clearance.     

Age Differences in Neural Activity during Slot Machine Gambling: An fMRI Study

This study aimed to assess the potential association between age-related prefrontal brain changes and slot machine gambling, an activity that has become increasingly popular among older adults. Functional magnetic resonance imaging was used to assess healthy older and younger adults whilst playing a slot machine. Results revealed that the older group over-recruited several bilateral and contralateral brain structures relative to the younger group. Specifically, older adults exhibited increased neural activation in the superior prefrontal cortex and left orbitofrontal cortex, indicating greater reliance on these structures. These results suggest a compensatory mechanism, by which older adults recruit a greater number of neural networks from both hemispheres to complete the same gambling task as their younger peers. The broader implications of these findings are discussed in relation to theories of neurocognitive and degenerative change that occurs in late adulthood.     

Differences of cardiac output measurements by open-circuit acetylene uptake in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a cohort study

Background

As differences in gas exchange between pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have been demonstrated, we asked if cardiac output measurements determined by acetylene (C₂H₂) uptake significantly differed in these diseases when compared to the thermodilution technique.

Method

Single-breath open-circuit C₂H₂ uptake, thermodilution, and cardiopulmonary exercise testing were performed in 72 PAH and 32 CTEPH patients.

Results

In PAH patients the results for cardiac output obtained by the two methods showed an acceptable agreement with a mean difference of -0.16 L/min (95% CI -2.64 to 2.32 L/min). In contrast, the agreement was poorer in the CTEPH group with the difference being -0.56 L/min (95% CI -4.96 to 3.84 L/min). Functional dead space ventilation (44.5 ± 1.6 vs. 32.2 ± 1.4%, p < 0.001) and the mean arterial to end-tidal CO₂ gradient (9.9 ± 0.8 vs. 4.1 ± 0.5 mmHg, p < 0.001) were significantly elevated among CTEPH patients.

Conclusion

Cardiac output evaluation by the C₂H₂ technique should be interpreted with caution in CTEPH, as ventilation to perfusion mismatching might be more relevant than in PAH.     

Pulmonary hypertension in patients with Martorell hypertensive leg ulcer: a case control study

Background

Martorell hypertensive ischemic leg ulcer (Martorell ulcer) is characterized by distinct alterations in the arteriolar wall of subcutaneous vessels, leading to progressive narrowing of the vascular lumen and increase of vascular resistance. These changes are similar to the alterations observed in pulmonary arterioles in patients with chronic pulmonary hypertension (PH). This study was aimed to assess an association between the two disorders.

Methods

In this case–control study, 14 patients with Martorell ulcer were clinically assessed for the presence of pulmonary hypertension using transthoracic Doppler echocardiography. Data from patients were compared to 28 matched hypertensive controls.

Results

Systolic pulmonary arterial pressure (sPAP) in patients with Martorell ulcer was significantly higher than in the control group (33.8 ± 16.9 vs 25.3 ± 6.5 mmHg, p = 0.023); the prevalence of pulmonary hypertension was 31% (5/14) in patients and 7% (2/28) in controls (p = 0.031). No differences were seen in left heart size and function between patients and controls.

Conclusion

This study provides first evidence that subcutaneous arteriolosclerosis, the hallmark of Martorell ulcer, is associated with PH. These findings suggest that patients with Martorell leg ulcer might be at significant risk to develop elevated pulmonary arterial pressure. Patients with leg ulcers who present with dyspnea should be evaluated by echocardiography for the presence of pulmonary hypertension.     

Wnt7a-Fzd7 signalling directly activates the Akt/mTOR anabolic growth pathway in skeletal muscle

Wnt7a signals through its receptor Fzd7 to activate the planar-cell-polarity pathway and drive the symmetric expansion of satellite stem cells resulting in enhanced repair of skeletal muscle. In differentiated myofibres, we observed that Wnt7a binding to Fzd7 directly activates the Akt/mTOR growth pathway, thereby inducing myofibre hypertrophy. Notably, the Fzd7 receptor complex was associated with Gα(s) and PI(3)K and these components were required for Wnt7a to activate the Akt/mTOR growth pathway in myotubes. Wnt7a-Fzd7 activation of this pathway was completely independent of IGF-receptor activation. Together, these experiments demonstrate that Wnt7a-Fzd7 activates distinct pathways at different developmental stages during myogenic lineage progression, and identify a non-canonical anabolic signalling pathway for Wnt7a and its receptor Fzd7 in skeletal muscle.     

The effect of fat mass on educational attainment: Examining the sensitivity to different identification strategies

The literature that examines the relationship between child or adolescent Body Mass Index (BMI) and academic attainment generally finds mixed results. This may be due to the use of different data sets, conditioning variables, or methodologies: studies either use an individual fixed effects (FE) approach and/or an instrumental variable (IV) specification. Using one common dataset, the Avon Longitudinal Study of Parents and Children, and a common set of controls, this paper compares the different approaches (including using different types of IV's), discusses their appropriateness, and contrasts their findings. We show that, although the results differ depending on the approach, most estimates cannot be statistically distinguished from OLS, nor from each other. Examining the potential violations of key assumptions of the different approaches and comparing their point estimates, we conclude that fat mass is unlikely to be causally related to academic achievement in adolescence.