Disturbed Laminar Blood Flow Causes Impaired Fibrinolysis and Endothelial Fibrin Deposition In Vivo

Endothelial expression of tissue-type plasminogen activator (t-PA) is crucial for maintaining an adequate endogenous fibrinolysis. It is unknown how endothelial t-PA expression and fibrinolysis are affected by blood flow in vivo. In this study, we investigated the impact of different blood flow profiles on endothelial t-PA expression and fibrinolysis in the arterial vasculature. Induction of disturbed laminar blood flow (D-flow) in the mouse carotid artery potently reduced endothelial t-PA messenger ribonucleic acid and protein expression, and caused fibrin deposition. En face immunohistochemistry demonstrated that arterial areas naturally exposed to D-flow had markedly lower endothelial t-PA levels than areas with sustained laminar blood flow (S-flow), and displayed pronounced fibrin deposition despite an intact endothelium. In t-PA and plasminogen-deficient mice, fibrin deposition did not extend into S-flow areas, indicating that areas of D-flow and S-flow differ, not only in fibrinolytic capacity, but also in coagulation. Furthermore, plasminogen accumulation was found at D-flow areas, and infusion of recombinant t-PA activated fibrinolysis and significantly reduced the fibrin deposits. In conclusion, D-flow potently impairs the fibrinolytic capacity and causes endothelial fibrin deposition in vivo. Our data also indicate that t-PA is the limiting factor for efficient fibrinolysis at the thrombosis-prone D-flow areas in the arterial vasculature.

Vimentin deficiency in macrophages induces increased oxidative stress and vascular inflammation but attenuates atherosclerosis in mice

The aim was to clarify the role of vimentin, an intermediate filament protein abundantly expressed in activated macrophages and foam cells, in macrophages during atherogenesis. Global gene expression, lipid uptake, ROS, and inflammation were analyzed in bone-marrow derived macrophages from vimentin-deficient (Vim-/-) and wild-type (Vim+/+) mice. Atherosclerosis was induced in Ldlr-/- mice transplanted with Vim-/- and Vim+/+ bone marrow, and in Vim-/- and Vim+/+ mice injected with a PCSK9 gain-of-function virus. The mice were fed an atherogenic diet for 12-15 weeks. We observed impaired uptake of native LDL but increased uptake of oxLDL in Vim-/- macrophages. FACS analysis revealed increased surface expression of the scavenger receptor CD36 on Vim-/- macrophages. Vim-/- macrophages also displayed increased markers of oxidative stress, activity of the transcription factor NF-κB, secretion of proinflammatory cytokines and GLUT1-mediated glucose uptake. Vim-/- mice displayed decreased atherogenesis despite increased vascular inflammation and increased CD36 expression on macrophages in two mouse models of atherosclerosis. We demonstrate that vimentin has a strong suppressive effect on oxidative stress and that Vim-/- mice display increased vascular inflammation with increased CD36 expression on macrophages despite decreased subendothelial lipid accumulation. Thus, vimentin has a key role in regulating inflammation in macrophages during atherogenesis.

Effects of polychlorinated biphenyls (PCB) on California sea lion (Zalophus californianus) lymphocyte functions upon in vitro exposure

Polychorinated biphenyl (PCB) congeners are a cause for concern due to their persistence in the environment, their lipophilic properties that cause them to bio-accumulate in top predators, and their adverse effects on mammalian health. For example, the common urogenital carcinoma reported in California sea lions (Zalophus californianus) (CSL) is associated with high tissue levels of PCBs, but the mechanisms responsible for this association are unknown. This study investigated the effect of exposure to six PCB congeners and a congener mix at low and environmentally relevant concentrations on NK cell-like and T cell activity using in vitro assays on cryopreserved lymph node mononuclear cells isolated from dead CSL. Non dioxin-like congeners 153 and 180 increased lymphocyte proliferation at 5 and 10 ppm, while congener 138 decreased proliferation by up to 43% at 15 ppm. Dioxin-like PCBs 118 and 169 did not affect lymphocyte proliferation, while the effects of congener 105 depended on the mitogen concentration; these did not correlate with their predicted toxic equivalent factors. NK cell-like activity was affected only by the highest concentration of PCBs tested; it was increased by non-dioxin-like congeners 138 and 153, and decreased by dioxin-like congener 169. The PCB congener mix suggested that the effects of PCB congeners were not simply additive. Our results concur with effects of PCBs reported for other pinniped's lymphocytes and add further experimental support to the observation that dioxin-like PCBs are not the most toxic congeners for marine mammals, contrary to effects in other species. This is the first evidence of in vitro suppression of NK cell-like cytotoxicity by a dioxin-like congener in a pinniped. More importantly, the observed results suggest that PCBs can modulate the CSL immune system, increasing exposed individuals' susceptibility to viral and oncogenic challenges.

Endothelial repair is dependent on CD11c+ leukocytes to establish regrowing endothelial sheets with high cellular density

Endothelial injury makes the vessel wall vulnerable to cardiovascular diseases. Injured endothelium regenerates by collective sheet migration, that is, the endothelial cells coordinate their motion and regrow as a sheet of cells with retained cell-cell contacts into the wounded area. Leukocytes appear to be involved in endothelial repair in vivo; however, little is known about their identity and role in the reparative sheet migration process. To address these questions, we developed a high-quality en face technique that enables visualizing of leukocytes and endothelial cells simultaneously following an endoluminal scratch wound injury of the mouse carotid artery. We discovered that regrowing endothelium forms a broad proliferative front accompanied by CD11c⁺ leukocytes. Functionally, the leukocytes were dispensable for the initial migratory response of the regrowing endothelial sheet, but critical for the subsequent formation and maintenance of a front zone with high cellular density. Marker expression analyses, genetic fate mapping, phagocyte targeting experiments, and mouse knock-out experiments indicate that the CD11c⁺  leukocytes were mononuclear phagocytes with an origin from both Ly6C^high and Ly6C^low monocytes. In conclusion, CD11c⁺ mononuclear phagocytes are essential for a proper endothelial regrowth following arterial endoluminal scratch injury. Promoting the endothelial-preserving function of CD11c⁺  leukocytes may be a strategy to enhance endothelial repair following surgical and endovascular procedures.

Toxicity of pristine and paint-embedded TiO2 nanomaterials

Little is known on the toxicity of nanomaterials in the user phase. Inclusion of nanomaterials in paints is a common nanotechnology application. This study focuses on the toxicity of dusts from sanding of paints containing nanomaterials. We compared the toxicity of titanium dioxide nanomaterials (TiO₂NMs) and dusts generated by sanding boards coated with paints with different amounts of two different types of uncoated TiO₂NMs (diameters:10.5 nm and 38 nm). Mice were intratracheally instilled with a single dose of 18, 54 and 162 µg of TiO₂NMs or 54, 162 and 486 µg of sanding dusts. At 1, 3 and 28 days post-instillation, we evaluated pulmonary inflammation, liver histology and DNA damage in lung and liver. Pulmonary exposure to both pristine TiO₂NMs and sanding dusts with different types of TiO₂NMs resulted in dose-dependently increased influx of neutrophils into the lung lumen. There was no difference between the sanding dusts from the two paints. For all exposures but not in vehicle controls, mild histological lesions were observed in the liver. Pulmonary exposure to pristine TiO₂NMs and paint dusts with TiO₂NMs caused similar type of histological lesions in the liver.

Intimal hyperplasia induced by vascular intervention causes lipoprotein retention and accelerated atherosclerosis

Accelerated atherosclerosis diminishes the long term patency of vascular interventions, such as percutaneous coronary intervention and implantation of saphenous vein grafts. However, the cause of this accelerated atherosclerosis is unclear. In this study, we tested the hypothesis that intimal hyperplasia formed following vascular intervention promotes retention of atherogenic lipoproteins. Intimal hyperplasia was surgically induced in the mouse common carotid artery. The surgery was combined with different mouse models of hypercholesterolemia to obtain different cholesterol levels and to control the onsets of hypercholesterolemia. Three weeks after surgery, samples were immunostained for apoB lipoproteins, smooth muscle cells and leukocytes. Already at mild hypercholesterolemia (193 mg/dL), pronounced apoB lipoprotein retention was found in the extracellular matrix in both intimal hyperplasia and the injured underlying media. In contrast, minimal retention was detected in the uninjured proximal region of the same vessel, or in vessels from mice with normal cholesterol levels (81 mg/dL). Induction of aggravated hypercholesterolemia 3 weeks after surgery, when a mature intimal hyperplasia had been formed, caused a very rapid development of atherosclerotic lesions. Mechanistically, we show that lipoprotein retention was almost exclusively dependent on electrostatic interactions to proteoglycan glycosaminoglycans, and the lipoprotein retention to intimal hyperplasia could be inhibited in vivo using glycosaminoglycan‐binding antibodies. Thus, formation of intimal hyperplasia following vascular intervention makes the vessel wall highly susceptible for lipoprotein retention and accelerated atherosclerosis. The increased lipoprotein retention in intimal hyperplasia can be targeted by blocking the interaction between apoB lipoproteins and glycosaminoglycans in the extracellular matrix.

Epidermal growth factor receptor function in the human urothelium

PURPOSE

Epidermal growth factor receptor (EGFr)-targeted therapy may be used in subgroups of patients with urinary bladder cancer. Here we assessed the role of EGFr in urothelial proliferation and migration in a two- and three-dimensional cell culture system.

METHODS

UROtsa cells derived from normal urothelium and malignant T24 cells were cultured in a Type I collagen gel. Proliferation and migration of urothelial cells, in the absence and presence of the EGFr inhibitor cetuximab, were assessed with a proliferation test (ATCC) and with the Axioplan 2 imaging microscope with a motorized stage (Carl Zeiss), respectively. The expressions of cytokeratin (CK) 17, CK20, EGFr, pEGFr, laminin, occludin and zonula occludens 1 (ZO-1) were assessed with immunohistochemistry and/or western blot.

RESULTS

UROtsa spheroids were formed after 7 days in culture, while T24 cells did not form spheroids. UROtsa expressed CK20 but not laminin or CK17 and consequently resembled umbrella cells. In UROtsa and T24, cetuximab inhibited urothelial proliferation, induced cleavage of EGFr and/or pEGFR but did not affect urothelial migration. The tight junction protein occludin was cleaved, and the formation of cellular spheroids was inhibited in UROtsa by the presence of cetuximab.

CONCLUSIONS

EGFr modulates urothelial proliferation and the formation of the three-dimensional structure of the urothelium possibly by interfering with occludin. The present data also show a cell culture technique enabling phenotypically normal urothelial cells to form epithelial structures in contrast to malignant urothelial cells.

National clinical practice guidelines for allergen immunotherapy: An international assessment applying AGREE-II

BACKGROUND

Since 1988, numerous allergen immunotherapy guidelines (AIT-GLs) have been developed by national and international organizations to guide physicians in AIT. Even so, AIT is still severely underused.

OBJECTIVE

To evaluate AIT-GLs with AGREE-II, developed in 2010 by McMaster University methodologists to comprehensively evaluate GL quality.

METHODS

Allergist, from different continents, knowledgeable in AIT and AGREE-II trained were selected into the project team. The project received methodologists' guidance. AIT-GLs in any language were sought from 1980 to 2016; AIT-GLs were AGREE II-evaluated by at least 2 team members, independently; discrepancies were resolved in a second round, by team discussion or methodologists' consulting.

RESULTS

We found 31 AIT-GLs (15 post-2010), ranging from local consensus reports to international position papers (EAACI, AAAAI-ACAAI, WAO). Pre-2010 GLs scored 1.6-4.6 (23%-67%) and post-2010 GLs scored 2.1-6 (30%-86%), on a 7-point Likert scale. The highest scores went to: German-Austrian-Swiss (6.0), Mexican (5.1), and the AAAAI/ACAAI AIT-GL (4.7). These were also the only 3 GLs that received "yes" of both evaluators to the item: "I would recommend this GL for use." The domains of "Stakeholder involvement" and "Rigor of Development" only scored 3/7, and "Applicability" scored the lowest. Strikingly, newer GLs only scored clearly better in "Editorial independence" and "Global evaluation."

CONCLUSIONS

In AIT-GLs, there is still a lot of room for improvement, especially in domains crucial for the dissemination. For some GLs, the "Scientific rigor" domain flawed. When resources are limited, transculturizing a high-quality GL might be preferable over developing a GL from zero. Our study and AGREE-II could help to select the best candidate.

CLINICAL IMPLICATIONS

We here evaluate allergen immunotherapy guideline (AIT-GL) quality. Only high-quality AIT-GLs should be consulted for AIT management decisions. In low-resource settings, transculturization of these is preferred over developing low-quality guidelines.

Identifying environmental barriers to participation: Usability of a health-literacy informed problem-identification approach for parents of young children with developmental disabilities

BACKGROUND

Parents of very young children recently diagnosed with developmental disabilities (DD) need to identify environmental barriers to their children's participation and adopt an adaptive orientation to solving these problems. Given the health service disparities for diverse families, parents may benefit from easy to use problem-identification approaches that address environmental barriers stemming from community and policy contexts. This feasibility study evaluated the usability of a health literacy-informed, structured, environment-focused problem-identification approach for parents of young children with DD.

METHODS

We used purposeful, convenience sampling to enrol 9 mothers of children ages 1-3 with DD (4 racial/ethnic minorities, 3 high school education, 4 annual household income <$20,000). We developed a structured problem-identification approach guided by a social ecological model featuring home, community, and policy contexts. The approach was applied to 3 short stories during a narrative elicitation interview. Two researchers independently coded parent responses for the type of barrier and solution identified with and without the approach.

RESULTS

Parents identified 121 environmental barriers without the approach. When using the approach and prompted to consider home, community, and policy barriers, parents identified an additional 222 environmental barriers; the greatest number of barriers were aligned with International Classification of Functioning, Disability, and Health-Children and Youth environment Chapter 5 "Services, systems, and policies." Using the approach, parents with a postgraduate education and annual household income >$80,000 identified the most environmental barriers, and parents reporting the lowest annual household incomes identified the fewest environmental barriers. When parents attributed participation challenges to an environmental barrier, ~57% of solutions required parents to interact with individuals at the community or policy level.

CONCLUSIONS

This study suggests that parents with a range of background characteristics can use a structured, environment-focused problem-identification approach. With the approach, parents are more likely to attribute participation challenges to environmental barriers and adopt a problem-solving orientation focused on changes to the community and policy context.

Zoonotic helminth exposure and risk of allergic diseases: A study of two generations in Norway

BACKGROUND

Animal and human studies indicate that definitive host helminth infections may confer protection from allergies. However, zoonotic helminths, such as Toxocara species (spp.), have been associated with increased allergies.

OBJECTIVE

We describe the prevalence of Toxocara spp. and Ascaris spp. seropositivity and associations with allergic diseases and sensitization, in 2 generations in Bergen, Norway.

METHODS

Serum levels of total IgG4, anti-Toxocara spp. IgG4 and Ascaris spp. IgG4 were established by ELISA in 2 cohorts: parents born 1945-1972 (n = 171) and their offspring born 1969-2003 (n = 264). Allergic outcomes and covariates were recorded through interviews and clinical examinations including serum IgEs and skin prick tests.

RESULTS

Anti-Ascaris spp. IgG4 was detected in 29.2% of parents and 10.3% of offspring, and anti-Toxocara spp. IgG4 in 17.5% and 8.0% of parents and offspring, respectively. Among offspring, anti-Toxocara spp. IgG4 was associated with pet keeping before age 15 (OR = 6.15; 95% CI = 1.37-27.5) and increasing BMI (1.16[1.06-1.25] per kg/m² ). Toxocara spp. seropositivity was associated with wheeze (2.97[1.45- 7.76]), hayfever (4.03[1.63-9.95]), eczema (2.89[1.08-7.76]) and cat sensitization (5.65[1.92-16.6]) among offspring, but was not associated with allergic outcomes among parents. Adjustment for childhood or current pet keeping did not alter associations with allergies. Parental Toxocara spp. seropositivity was associated with increased offspring allergies following a sex-specific pattern.

CONCLUSIONS & CLINICAL RELEVANCE

Zoonotic helminth exposure in Norway was less frequent in offspring than parents; however, Toxocara spp. seropositivity was associated with increased risk of allergic manifestations in the offspring generation, but not among parents. Changes in response to helminth exposure may provide insights into the increase in allergy incidence in affluent countries.

Tissue Factor Pathway Inhibitor (TFPI) Levels in the Plasma and Urine of Children with Meningococcal Disease

Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of the TF-dependent coagulation system. In meningococcal disease, up-regulation of tissue factor expression on blood monocytes and possibly on endothelial cells has the potential to trigger the activation of the TF-dependent pathway of coagulation. Intravascular coagulation is considered to be a major pathogenic factor in meningococcal disease. We postulated that imbalance between TF expression and TFPI concentration might lead to uncontrolled coagulation in meningococcal disease. The aim of this study was to assess the levels of total TFPI in the plasma of patients with meningococcal disease and assess whether increased leaking of the TFPI was occurring. TFPI antigen levels and activity were measured in the plasma of 54 patients with meningococcal disease, and 13 healthy control children. TFPI antigen level were also determined in the urines of 14 of the 54 and 9 healthy control children. Plasma TFPI activity was reduced in the meningococcal diseased patients (mean of 0.503 ± 0.341 U/ml; control, 1.010 ± 0.199 U/ml; p <0.0001), as was the TFPI antigen levels (mean of 54.85 ± 35.05 ng/ ml; Control, 94.51 ± 11.44 ng/ml; p <0.0001). In contrast, TFPI antigen levels were increased in the urine of these patients when compared to the levels found in the urine of the healthy control children (mean of 12.96 ± 5.392 ng/mmol creatinine; Control, 0.239 ± 0.191 ng/mmol creatinine; p <0.035). A lack of correlation between TFPI-activity and TFPI-antigen plasma levels was observed (r = 0.002, p = 0.85). This data is consistent with the hypothesis that in meningococcal disease there is increased inactivation of plasma TFPI by the up regulation of tissue factor expression but in addition increased clearance of TFPI in urine is occurring.

Stable Transmission of Borrelia burgdorferi Sensu Stricto on the Outer Banks of North Carolina

The spirochaete (Borrelia burgdorferi) associated with Lyme disease was detected in questing ticks and rodents during a period of 18 years, 1991-2009, at five locations on the Outer Banks of North Carolina. The black-legged tick (Ixodes scapularis) was collected at varied intervals between 1991 and 2009 and examined for B. burgdorferi. The white-footed mouse (Peromyscus leucopus), house mouse (Mus musculus) marsh rice rat (Oryzomys palustris), marsh rabbit (Sylvilagus palustris), eastern cottontail (Sylvilagus floridanus) and six-lined racerunner (Cnemidophorus sexlineatus) were live-trapped, and their tissues cultured to isolate spirochaetes. Borrelia burgdorferi isolates were obtained from questing adult I. scapularis and engorged I. scapularis removed from P. leucopus, O. palustris and S. floridanus. The prevalence of B. burgdorferi infection was variable at different times and sites ranging from 7 to 14% of examined questing I. scapularis. Mitochondrial (16S) rRNA gene phylogenetic analysis from 65 adult I. scapularis identified 12 haplotypes in two major clades. Nine haplotypes were associated with northern/Midwestern I. scapularis populations and three with southern I. scapularis populations. Sixteen isolates obtained from tick hosts in 2005 were confirmed to be B. burgdorferi by amplifying and sequencing of 16S rRNA and 5S-23S intergenic spacer fragments. The sequences had 98-99% identity to B. burgdorferi sensu stricto strains B31, JD1 and M11p. Taken together, these studies indicate that B. burgdorferi sensu stricto is endemic in questing I. scapularis and mammalian tick hosts on the Outer Banks of North Carolina.