A novel pH-sensitive liposome formulation containing oleyl alcohol

AbstractpH-sensitive liposomes are designed to undergo acid-triggered destabilization. First generation pH-sensitive liposomes, based on the cone-shaped lipid dioleoylphosphatidylethanolamine (DOPE), have been shown to lose fusogenicity in the presence of serum. Here, we report the design and evaluation of novel serum-resistant pH-sensitive liposome formulations that are based on the composition of egg phosphatidylcholine (PC), cholesteryl hemisuccinate (CHEMS), oleyl alcohol (OAlc), and Tween-80 (T-80). When loaded with the fluorescent probe calcein, these liposomes exhibited excellent stability at pH 7.4 and underwent rapid destabilization upon acidification as shown by calcein dequenching and particle size increase. Adjusting the mole percentages of T-80 and OAlc in the formulation could regulate the stability and pH-sensitive properties of these liposomes. Liposomes with a higher T-80 content exhibited greater stability but were less sensitive to acid-induced destabilization. Meanwhile, formulations with a higher OAlc content exhibited greater content release in response to low pH. The pH-triggered liposomal destabilization did not produce membrane fusion according to an octadecylrhodamine B chloride (R18) lipid-mixing assay. Compared to DOPE-based pH-sensitive liposomes, the above formulations showed much better retention of their pH-sensitive properties in the presence of 10% serum. These liposomes were then evaluated for intracellular delivery of entrapped cytosine-β-d-arabinofuranoside (araC) in KB human oral cancer cells, which have elevated folate receptor (FR) expression. The FR, which is amplified in many types of human tumors, has been shown to mediate the internalization of folate-derivatized liposomes into an acidic intracellular compartment. FR-targeted OAlc-based pH-sensitive liposomes, entrapping 200 mM araC, showed ∼17-times greater FR-dependent cytotoxicity in KB cells compared to araC delivered via FR-targeted non-pH-sensitive liposomes. These data indicated that pH-sensitive liposomes based on OAlc, combined with FR-mediated targeting, are promising delivery vehicles for membrane impermeable therapeutic agents

Filtration of Macrophage Migration Inhibitory Factor (MIF) in Patients with End Stage Renal Disease Undergoing Hemodialysis

<div><p>Background</p><p>End stage renal disease (ESRD) patients are characterized by increased morbidity and mortality due to highest prevalence of cardiovascular disease. Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that controls cellular signaling in human physiology, pathophysiology, and diseases. Increased MIF plasma levels promote vascular inflammation and development of atherosclerosis. We have shown that MIF is associated with vascular dysfunction in ESRD patients. Whether hemodialysis (HD) affects circulating MIF plasma levels is unknown. We here aimed to investigate whether HD influences the circulating MIF pool in ESRD patients.</p><p>Methods and Results</p><p>An observational single-center study was conducted. MIF plasma levels in ESRD patients were assessed before, during, and after a HD session (n = 29). Healthy age-matched volunteers served as controls to compare correlations of MIF plasma levels with inflammatory plasma components (n = 20). MIF removed from the circulating blood pool could be detected in the dialysate and allowed for calculation of totally removed MIF (MIF content in dialysate 219±4 μg/HD-session). MIF plasma levels were markedly decreased 2 hour after initiation of HD (MIF plasma level pre-HD 84.8±6 ng/ml to intra-HD 61.2±5 ng/ml p<0.001) and were replenished already 20 min after termination of HD to basal levels (intra-HD 61.2±5 ng/ml to post-HD 79.8±5 ng/ml, p<0.001).</p><p>Conclusion</p><p>MIF is a dialyzable plasma component that is effectively filtrated during HD from the patient blood pool in large amounts. After removal of remarkable amounts of MIF during a single HD session, MIF plasma pool is early reconstituted after termination of HD from unknown sources.</p></div

Additional file 3: Figure S3. of Evaluating the effectiveness of IV iron dosing for anemia management in common clinical practice: results from the Dialysis Outcomes and Practice Patterns Study (DOPPS)

Distribution of 3-month IV iron dose. (PPTX 546 kb

Platelets are associated with MIF plasma levels in ESRD patients but not in healthy controls.

<p><b>A</b>) Platelets count does not differ between ESRD patients and healthy controls. <b>B</b>) Platelets count correlates with MIF plasma levels in ESRD patients (p<0.02). <b>C</b>) Healthy subjects show no correlation between platelets and circulating MIF levels (p = ns).</p

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06 janvier 18821882/01/06 (A11,N4538)-1882/01/06.Appartient à l’ensemble documentaire : PoitouCh

MIF plasma level decrease during HD and restore after termination of renal replacement therapy.

<p><b>A</b>) MIF plasma level decrease during HD (Intra-HD) compared to baseline levels (Pre-HD) (p<0.01). After termination of HD (Post-HD), MIF plasma level return to baseline values (Pre-HD vs. Post-HD; p = ns). <b>B</b>) MIF can be measured in the ultrafiltrate (UF) immediately after beginning of HD (HD start). Concentration of MIF in UF does not change over time as demonstrated by measurements at the end of HD session (HD end)(p = ns). <b>C</b>) The absolute amount of removed MIF is associated with the baseline amounts of MIF plasma levels in ESRD patients (p<0.01).</p

Hemodialysis removes large amounts of MIF from the circulating MIF plasma pool.

<p>Illustration of the experiment shows the estimated amount of circulating MIF levels in our patient cohort. Plasma levels were calculated being 5% of body weight (4.3L). Multiplication with the measured average MIF plasma level revealed an amount of 370 μg/patient. An average amount of 219±39 μg MIF was removed in a single HD session.</p

Increased MIF levels in ESRD show no association with inflammation.

<p>Inflammatory parameters (C reactive protein; CRP, white blood cells; WBC, oxidized LDL; oxLDL) were measured in ESRD after termination of HD and in healthy controls under resting conditions. Neither in ESRD nor in control MIF levels correlate with inflammatory parameters.</p

Flowchart of recruited patients.

<p>The included ESRD patients represent a random sample of a larger group of patients (n = 57) in which the influence of flavanols on vascular function in ESRD patients is investigated. Of these, n = 29 were consecutively assigned for analysis of MIF plasma level before, during and after hemodialysis (HD). The different time points for blood sample collection were 20 min before start of HD (t₁), 2 hours after start of HD (t₂) and 20 min after termination of HD (t₃).</p