Atrial natriuretic peptide down-regulates neutrophil recruitment on inflamed endothelium by reducing cell deformability and resistance to detachment force

Natriuretic peptide receptor-C mediates the inhibitory effect of atrial natriuretic peptide on neutrophil recruitment to the lung during acute lung injury

Atrial natriuretic peptide (ANP) protects against acute lung injury (ALI), but the receptor that mediates this effect is not known. Transgenic mice with 0 (knockout), 1 (heterozygote), or 2 (wild-type) functional copies of Npr3, the gene that encodes for natriuretic peptide receptor-C (NPR-C), were treated with intravenous infusion of ANP or saline vehicle before oropharyngeal aspiration of Pseudomonas aeruginosa (PA103) or saline vehicle. Lung injury was assessed 4 h following aspiration by measurement of lung wet/dry (W/D) weight, whole lung leukocyte and cytokine levels, and protein, leukocyte, and cytokine concentration in bronchoalveolar lavage fluid (BALF). PA103 induced acute lung injury as evidenced by increases in lung W/D ratio and protein concentration in BALF. The severity of PA103-induced lung injury did not differ between NPR-C genotypes. Treatment with intravenous ANP infusion reduced PA103-induced increases in lung W/D and BALF protein concentration in all three NPRC genotypes. PA103 increased the percentage of leukocytes that were neutrophils and cytokine levels in whole lung and BALF in NPR-C wild-type and knockout mice. This effect was blunted by ANP in wild-type mice but not in the NPR-C knockout mice. NPR-C does not mediate the protective effect of ANP on endothelial cell permeability in settings of PA103-induced injury but may mediate the effect of ANP on inhibition of the recruitment of neutrophils to the lung and thereby attenuate the release of inflammatory cytokines.

A Tumor-on-a-Chip System with Bioprinted Blood and Lymphatic Vessel Pair

Current in vitro anti-tumor drug screening strategies are insufficiently portrayed lacking true perfusion and draining microcirculation systems, which may post significant limitation in reproducing the transport kinetics of cancer therapeutics explicitly. Herein, we report the fabrication of an improved tumor model consisting of bioprinted hollow blood vessel and lymphatic vessel pair, hosted in a three-dimensional (3D) tumor microenvironment-mimetic hydrogel matrix, termed as the tumor-on-a-chip with bioprinted blood and lymphatic vessel pair (TOC-BBL). The bioprinted blood vessel was perfusable channel with opening on both ends while the bioprinted lymphatic vessel was blinded on one end, both of which were embedded in a hydrogel tumor mass, with vessel permeability individually tunable through optimization of the composition of the bioinks. We demonstrated that systems with different combinations of these bioprinted blood/lymphatic vessels exhibited varying levels of diffusion profiles for biomolecules and anti-cancer drugs. Our TOC-BBL platform mimicking the natural pathway of drug-tumor interactions would have the drug introduced through the perfusable blood vessel, cross the vascular wall into the tumor tissue via diffusion, and eventually drained into the lymphatic vessel along with the carrier flow. Our results suggested that this unique in vitro tumor model containing the bioprinted blood/lymphatic vessel pair may have the capacity of simulating the complex transport mechanisms of certain pharmaceutical compounds inside the tumor microenvironment, potentially providing improved accuracy in future cancer drug screening.

Circulating proteomic patterns in AF related left atrial remodeling indicate involvement of coagulation and complement cascade

BACKGROUND

Left atrial (LA) electro-anatomical remodeling and diameter increase in atrial fibrillation (AF) indicates disease progression and is associated with poor therapeutic success. Furthermore, AF leads to a hypercoagulable state, which in turn promotes the development of a substrate for AF and disease progression in the experimental setting. The aim of this study was to identify pathways associated with LA remodeling in AF patients using untargeted proteomics approach.

METHODS

Peripheral blood samples of 48 patients (62±10 years, 63% males, 59% persistent AF) undergoing AF catheter ablation were collected before ablation. 23 patients with left atrial low voltage areas (LVA), defined as <0.5 mV, and 25 patients without LVA were matched for age, gender and CHA2DS2-VASc score. Untargeted proteome analysis was performed using LC-ESI-Tandem mass spectrometry in a label free intensity based workflow. Significantly different abundant proteins were identified and used for pathway analysis and protein-protein interaction analysis.

RESULTS

Analysis covered 280 non-redundant circulating plasma proteins. The presence of LVA correlated with 30 differentially abundant proteins of coagulation and complement cascade (q<0.05).

CONCLUSIONS

This pilot proteomic study identified plasma protein candidates associated with electro-anatomical remodeling in AF and pointed towards an imbalance in coagulation and complement pathway, tissue remodeling and inflammation.

Selectin-Targeting Peptide-Glycosaminoglycan Conjugates Modulate Neutrophil-Endothelial Interactions

Introduction

The glycocalyx is a layer of glycoproteins, proteoglycans and glycosaminoglycans that coats the luminal surface of most blood vessels. It effectively regulates adhesive interactions between leukocytes in flowing blood and the endothelium, where during inflammation, binding to E- and P-selectins and intercellular adhesion molecule-1 (ICAM-1) promotes cell tethering and arrest under shear flow.

Methods

In this study, we examine the targeting of E-selectin by an engineered peptide moiety bound to a dermatan sulfate backbone. We further investigate this conjugate, denoted as EC-SEAL, by observing its binding to inflamed endothelium, and quantifying its ability to modulate neutrophil–endothelium interactions.

Results

Binding data reveal that EC-SEAL recognizes domains on E-selectin, and to a lesser degree on P- and L-selectin, and ICAM-1. Further, EC-SEAL increases neutrophil rolling velocity, and decreases neutrophil arrest and migration on inflamed human microvascular endothelial cells under physiologically relevant flow conditions.

Conclusions

We conclude that simple targeting strategies can mimic glycocalyx function under inflammatory conditions, effectively reducing neutrophil recruitment.

Electronic supplementary material

The online version of this article (10.1007/s12195-018-0555-6) contains supplementary material, which is available to authorized users.

The function of TRP channels in neutrophil granulocytes

Neutrophil granulocytes are exposed to widely varying microenvironmental conditions when pursuing their physiological or pathophysiological functions such as fighting invading bacteria or infiltrating cancer tissue. Examples for harsh environmental challenges include among others mechanical shear stress during the recruitment from the vasculature or the hypoxic and acidotic conditions within the tumor microenvironment. Chemokine gradients, reactive oxygen species, pressure, matrix elasticity, and temperature can be added to the list of potential challenges. Transient receptor potential (TRP) channels serve as cellular sensors since they respond to many of the abovementioned environmental stimuli. The present review investigates the role of TRP channels in neutrophil granulocytes and their role in regulating and adapting neutrophil function to microenvironmental cues. Following a brief description of neutrophil functions, we provide an overview of the electrophysiological characterization of neutrophilic ion channels. We then summarize the function of individual TRP channels in neutrophil granulocytes with a focus on TRPC6 and TRPM2 channels. We close the review by discussing the impact of the tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) on neutrophil granulocytes. Since neutrophil infiltration into PDAC tissue contributes to disease progression, we propose neutrophilic TRP channel blockade as a potential therapeutic option.

Natriuretic Peptides: The Case of Prostate Cancer

Cardiac natriuretic peptides have long been known to act as main players in the homeostatic control of blood pressure, salt and water balance. However, in the last few decades, new properties have been ascribed to these hormones. A systematic review of English articles using MEDLINE Search terms included prostate cancer, inflammation, cardiac hormones, atrial natriuretic peptide, and brain natriuretic peptide. Most recent publications were selected. Natriuretic peptides are strongly connected to the immune system, whose two branches, innate and adaptive, are finely tuned and organized to kill invaders and repair injured tissues. These peptides control the immune response and act as anti-inflammatory and immune-modulatory agents. In addition, in cancers, natriuretic peptides have anti-proliferative effects by molecular mechanisms based on the inhibition/regulation of several pathways promoting cell proliferation and survival. Nowadays, it is accepted that chronic inflammation is a crucial player in prostate cancer development and progression. In this review, we summarize the current knowledge on the link between prostate cancer and inflammation and the potential use of natriuretic peptides as anti-inflammatory and anticancer agents.

Manifold implications of obesity in ischemic heart disease among Japanese patients according to covariance structure analysis: Low reactivity of B-type natriuretic peptide as an intervening risk factor

Background/Objectives

Obesity is believed to be one of the major risk factors for cardiovascular disease in Western countries. However, the effects of obesity should be continuously examined in the Japanese population because the average bodily habitus differs among countries. In this study, we collectively examined the significance of obesity and obesity-triggered risk factors including the low reactivity of B-type natriuretic peptide (BNP), for ischemic heart disease (IHD) in Japanese patients.

Methods and results

The study patients consisted of 1252 subjects (IHD: n = 970; non-IHD: n = 282). Multiple logistic regression analysis revealed that dyslipidemia, hypertension, diabetes, and the low reactivity of BNP were significant risk factors for IHD, but body mass index (BMI) was not. A theoretical path model was proposed by positioning BMI at the top of the hierarchical model. Exploratory factor analysis revealed that BMI did not play a causative role in IHD (P = NS). BMI was causatively linked to other risk factors (P<0.001 for hypertension; P<0.001 for dyslipidemia; P<0.001 for HbA1c; P<0.001 for LogBNP), and these factors played a causative role in IHD (P<0.001 for hypertension; P<0.001 for dyslipidemia; P<0.001 for HbA1c; P<0.001 for LogBNP). The intrinsic power of the low reactivity of BNP induced by high BMI on the promotion of IHD was fairly potent.

Conclusion

This study demonstrated that obesity per se is not a strong risk factor for IHD in Japanese patients. However, several important risk factors triggered by obesity exhibited a causative role for IHD. The low reactivity of BNP is a substantial risk factor for IHD.

The role of atrial natriuretic peptide to attenuate inflammation in a mouse skin wound and individually perfused rat mesenteric microvessels

We tested the hypothesis that the anti‐inflammatory actions of atrial natriuretic peptide (ANP) result from the modulation of leukocyte adhesion to inflamed endothelium and not solely ANP ligation of endothelial receptors to stabilize endothelial barrier function. We measured vascular permeability to albumin and accumulation of fluorescent neutrophils in a full‐thickness skin wound on the flank of LysM‐EGFP mice 24 h after formation. Vascular permeability in individually perfused rat mesenteric microvessels was also measured after leukocytes were washed out of the vessel lumen. Thrombin increased albumin permeability and increased the accumulation of neutrophils. The thrombin‐induced inflammatory responses were attenuated by pretreating the wound with ANP (30 min). During pretreatment ANP did not lower permeability, but transiently increased baseline albumin permeability concomitant with the reduction in neutrophil accumulation. ANP did not attenuate acute increases in permeability to histamine and bradykinin in individually perfused rat microvessels. The hypothesis that anti‐inflammatory actions of ANP depend solely on endothelial responses that stabilize the endothelial barrier is not supported by our results in either individually perfused microvessels in the absence of circulating leukocytes or the more chronic skin wound model. Our results conform to the alternate hypothesis that ANP modulates the interaction of leukocytes with the inflamed microvascular wall of the 24 h wound. Taken together with our previous observations that ANP reduces deformability of neutrophils and their strength of attachment, rolling, and transvascular migration, these observations provide the basis for additional investigations of ANP as an anti‐inflammatory agent to modulate leukocyte–endothelial cell interactions.