Use of silver nanowires to determine thresholds for fibre length-dependent pulmonary inflammation and inhibition of macrophage migration in vitro

<p>Abstract</p> <p>Background</p> <p>The objective of this study was to examine the threshold fibre length for the onset of pulmonary inflammation after aspiration exposure in mice to four different lengths of silver nanowires (AgNW). We further examined the effect of fibre length on macrophage locomotion in an <it>in vitro</it> wound healing assay. We hypothesised that exposure to longer fibres causes both increased inflammation and restricted mobility leading to impaired clearance of long fibres from the lower respiratory tract to the mucociliary escalator <it>in vivo</it>.</p> <p>Methods</p> <p>Nine week old female C57BL/6 strain mice were exposed to AgNW and controls via pharyngeal aspiration. The dose used in this study was equalised to fibre number and based on 50 μg/ mouse for AgNW₁₄. To examine macrophage migration <it>in vitro</it> a wound healing assay was used. An artificial wound was created in a confluent layer of bone marrow derived macrophages by scraping with a pipette tip and the number of cells migrating into the wound was monitored microscopically. The dose was equalised for fibre number and based on 2.5 μg/cm² for AgNW_14.</p> <p>Results</p> <p>Aspiration of AgNW resulted in a length dependent inflammatory response in the lungs with threshold at a fibre length of 14 μm. Shorter fibres including 3, 5 and 10 μm elicited no significant inflammation. Macrophage locomotion was also restricted in a length dependent manner whereby AgNW in the length of ≥5 μm resulted in impaired motility in the wound closure assay.</p> <p>Conclusion</p> <p>We demonstrated a 14 μm cut-off length for fibre-induced pulmonary inflammation after aspiration exposure and an <it>in vitro</it> threshold for inhibition of macrophage locomotion of 5 μm. We previously reported a threshold length of 5 μm for fibre-induced pleural inflammation. This difference in pulmonary and pleural fibre- induced inflammation may be explained by differences in clearance mechanism of deposited fibres from the airspaces compared to the pleural space. Inhibition of macrophage migration at long fibre lengths could account for their well-documented long term retention in the lungs compared to short fibres. Knowledge of the threshold length for acute pulmonary inflammation contributes to hazard identification of nanofibres.</p

Change in the prevalence of obesity and use of health care in Denmark:an observational study

PURPOSE: The purpose of this study was to examine the influence of the increasing prevalence of obesity on the development of health care utilization in Denmark in the period 1987–2005. PATIENTS AND METHODS: From a random sample of adult Danes (19,142 women and 18,335 men) who participated in the Danish Health Interview Surveys in 1987, 1994, 2000, and 2005, self-reported data on type of health care utilization within the previous 3 months and on height and weight were obtained. RESULTS: Adjusted odds ratios (ORs) showed that an increased use of health care among obese men compared with those of normal weight was pronounced and significant for those aged 45–64 years, whereas it was weaker and borderline significant for those aged 25–44 and 65+ years. Among obese men, there was an increasing use of health care until 2005. Among women, there was also an increased use of health care among the obese women in comparison with the normal weight women. An increase in the use of health care was found among obese women during 1987–2000, followed by a leveling of utilization during 2000–2005. CONCLUSIONS: In conclusion, this study showed that the increase in health care utilization in Denmark could, in part, be attributed to an increase in prevalence of obesity and to an increase in health care utilization among obese men in particular

Impact of renal insufficiency on mortality in patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention

BACKGROUND: Chronic kidney disease is associated with increased risk of mortality. We examined the impact of moderate and severe renal insufficiency (RI) on short- and long-term mortality among unselected patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). METHODS: From January 1, 2002 to December 31, 2010 all patients with STEMI treated with primary PCI were identified. The hazard ratio (HR) for death was estimated using a Cox regression model, controlling for potential confounders. RI was defined as creatinine clearance (CrCl) < 60 mL/min (moderate RI: CrCl ≤30 < 60 mL/min and severe RI: CrCl < 30 mL/min). RESULTS: The study cohort consisted of 4,116 patients of whom 898 (21.8%) had RI and 3,218 (78.2%) had a CrCl ≥ 60 mL/min. Compared to patients without RI, patients with RI were older, more often female and more likely to have diabetes mellitus, hypertension and to present with a higher Killip class. Among patients with a preserved kidney function and patients with RI, 30-day all-cause mortality was 3.5% vs. 20.9% (log-rank p < 0.001); 1-year all-cause mortality was 5.7% vs. 29.4% (log-rank p < 0.001); 5-year all-cause mortality was 13.4% vs. 47.4% (log-rank p < 0.001). Moderate and severe RI were associated with higher 1-year mortality compared to patients with a preserved renal function (CrCl ≤30 < 60 mL/min: adjusted HR 2.71 [95% CI 2.09-3.51], p < 0.001), and (CrCl < 30 mL/min: adjusted HR 7.09 [4.82-10.44], p < 0.001). CONCLUSION: In unselected STEMI patients treated with primary PCI, moderate and severe RI were associated with increased risk of mortality

Roles of neutrophils in the regulation of the extent of human inflammation through delivery of IL-1 and clearance of chemokines

This study examined the establishment of neutrophilic inflammation in humans. We tested the hypotheses that neutrophil recruitment was associated with local CXCL8 production and that neutrophils themselves might contribute to the regulation of the size of the inflammatory response. Humans were challenged i.d. with endotoxin. Biopsies of these sites were examined for cytokine production and leukocyte recruitment by qPCR and IHC. Additional in vitro models of inflammation examined the ability of neutrophils to produce and sequester cytokines relevant to neutrophilic inflammation. i.d. challenge with 15 ng of a TLR4-selective endotoxin caused a local inflammatory response, in which 1% of the total biopsy area stained positive for neutrophils at 6 h, correlating with 100-fold up-regulation in local CXCL8 mRNA generation. Neutrophils themselves were the major source of the early cytokine IL-1β. In vitro, neutrophils mediated CXCL8 but not IL-1β clearance (>90% clearance of ≤2 nM CXCL8 over 24 h). CXCL8 clearance was at least partially receptor-dependent and modified by inflammatory context, preserved in models of viral infection but reduced in models of bacterial infection. In conclusion, in a human inflammatory model, neutrophils are rapidly recruited and may regulate the size and outcome of the inflammatory response through the uptake and release of cytokines and chemokines in patterns dependent on the underlying inflammatory stimulus

Regulation of neutrophil senescence by microRNAs

Neutrophils are rapidly recruited to sites of tissue injury or infection, where they protect against invading pathogens. Neutrophil functions are limited by a process of neutrophil senescence, which renders the cells unable to respond to chemoattractants, carry out respiratory burst, or degranulate. In parallel, aged neutrophils also undergo spontaneous apoptosis, which can be delayed by factors such as GMCSF. This is then followed by their subsequent removal by phagocytic cells such as macrophages, thereby preventing unwanted inflammation and tissue damage. Neutrophils translate mRNA to make new proteins that are important in maintaining functional longevity. We therefore hypothesised that neutrophil functions and lifespan might be regulated by microRNAs expressed within human neutrophils. Total RNA from highly purified neutrophils was prepared and subjected to microarray analysis using the Agilent human miRNA microarray V3. We found human neutrophils expressed a selected repertoire of 148 microRNAs and that 6 of these were significantly upregulated after a period of 4 hours in culture, at a time when the contribution of apoptosis is negligible. A list of predicted targets for these 6 microRNAs was generated from http://mirecords.biolead.org and compared to mRNA species downregulated over time, revealing 83 genes targeted by at least 2 out of the 6 regulated microRNAs. Pathway analysis of genes containing binding sites for these microRNAs identified the following pathways: chemokine and cytokine signalling, Ras pathway, and regulation of the actin cytoskeleton. Our data suggest that microRNAs may play a role in the regulation of neutrophil senescence and further suggest that manipulation of microRNAs might represent an area of future therapeutic interest for the treatment of inflammatory disease

Combining creative writing and narrative analysis to deliver new insights into the impact of pulmonary hypertension

Introduction Pulmonary hypertension is life-limiting. Delays in diagnosis are common, and even after treatment has been initiated, pulmonary hypertension has marked effects on many aspects of social and physical function. We believed that a new approach to examining disease impact could be achieved through a combination of narrative research and creative writing. Methods Detailed unstructured narrative interviews with people with pulmonary hypertension were analysed thematically. Individual moments were also summarised and studied using creative writing, in which the interviewer created microstories from narrative and interview data. Stories were shared with their subjects, and with other patients, clinicians, researchers and the wider public. The study was carried out in hospital and in patients’ homes. Results Narrative analysis generated a rich data set which highlighted profound effects of pulmonary hypertension on identity, and demonstrated how the disease results in very marked personal change with ongoing and unpredictable requirement for adaptation. The novel methodology of microstory development proved to be an effective tool to summarise, communicate, and explore the consequences of pulmonary hypertension and the clinical challenges of caring for patients with this illness. Conclusions A holistic approach to treatment of chronic respiratory diseases such as pulmonary hypertension requires and benefits from explicit exploration of the full impacts of the illness. Narrative analysis and the novel approach of targeted microstory development can form a valuable component of the repertoire of approaches to effectively comprehend chronic disease and can also facilitate patient-focused discussion and interventions