Additional file 1: of Renal replacement therapy neutralizes elevated MIF levels in septic shock

Creatinine values. (TIFF 155 kb

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

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

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

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

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