The effect of three different miniaturized blood purification devices on plasma cytokine concentration in an ex vivo model of endotoxinemia

What blood temperature for an ex vivo extracorporeal circuit?

Ex vivo circuits are commonly used to evaluate biomaterials or devices used for extracorporeal blood purification. However, various aspects of the ex vivo circuit, apart from the circuit materials, may affect inflammation and coagulation. One such aspect is temperature. The aim of this study was to evaluate the influence of different blood temperature conditions on inflammation parameters in an ex vivo circuit. Blood was collected from 20 healthy volunteers and run through three different experimental conditions for 4 h: a miniaturized ex vivo extracorporeal circuit equipped with a blood warmer set to 37°C, the same circuit without the warmer (23°C), and a tube placed in an incubator at 37°C (no circuit). We measured the granulocyte macrophage colony-stimulating factor, the tumor necrosis factor, and the interleukin (IL)-1β, IL-6, IL-8, and IL-10 concentrations at baseline, 15, 60, 120, and 240 min. Human leukocyte antigen (HLA)-DR, CD11b, CD11a, CD62L, tumor necrosis factor alpha converting enzyme, annexin V expression, and NFkB DNA binding were measured in monocytes and polymorphonuclear neutrophils (PMNs) using flow cytometry at baseline, 120 min, and 240 min. While cytokine production over time was very slight at room temperature, levels increased by more than 100-fold in the two heated conditions. Differences in the expression of some surface markers were also observed between the room temperature circuit and the two heated conditions (CD11b PMN, P < 0.0001; HLA-DR Mono, P=0.0019; and CD11a PMN, P<0.0001). Evolution of annexin V expression was also different over time between the three groups (P=0.0178 for monocytes and P=0.0011 for PMNs). A trend for a greater NFkB DNA binding was observed in the heated conditions. Thus, for ex vivo studies using extracorporeal circuits, heating blood to maintain body temperature results in significant activation of inflammatory cells while hypothermia (room temperature) seems to suppress the leukocyte response. Both strategies may lead to erroneous conclusions, possibly masking some specific effects of the device being studied. Investigators in this field must be aware of the fact that blood temperature is a crucial confounding parameter and the type of "background noise" they will face depending on the strategy adopted.

Cytokines in blood from septic patients interact with surface-immobilized heparin

When passing blood from septic patients through a column packed with surface heparinized beads, we were able to significantly reduce concentrations of the proinflammatory cytokine tumor necrosis factor (TNF)-alpha from initially very high levels. Passage of blood over nonheparinized beads did not affect the TNF levels. Meanwhile, concentrations of the regulated on activation, normal T-cells expressed, and secreted leukocyte activating cytokine (RANTES) remained unchanged following passage through the heparinized column, but rose significantly after passage through a column packed with the nonheparinized control beads. We conclude that surface heparinization may be a useful technique for selectively regulating the levels of heparin-binding cytokines from whole blood. This may have potential implications for the treatment of hyper-inflammatory conditions such as severe sepsis. Our data also suggests that surface activation and its associated inflammatory response may be avoided by using heparinization of the extracorporeal circuit.

Differences in cytokine levels due to gender in colorectal cancer patients

INTRODUCTION

Female gender is associated with longer survival after treatment for colorectal cancer (CRC). Reasons behind this phenomenon are not entirely clear. In addition, higher interleukin-6 (IL-6) and interleukin-1 (IL-1) levels have been found to be associated with poorer prognosis in CRC patients. The aim of this study was to investigate if cytokine levels were different in male and female CRC patients.

METHODS

Pre- and post-operative levels of IL-1, interleukin-1 receptor antagonist (IL-1ra), IL-6 and tumour necrosis factor-alpha (TNF-alpha) were measured using standard solid phase sandwich ELISA in 104 consecutive eligible patients undergoing elective resection for CRC.

RESULTS

Seventy (67.3%) participants were male and the mean age of the group was 67.6years (standard deviation 10.4years, range 39-86years). Pre-operative IL-1beta and post-operative IL-6 levels were significantly higher in males compared with females (U=486.5, p=0.03, U=424, p=0.04), values approaching statistical significance were obtained for pre-operative IL-6 (U=508.5, p=0.06) and post-operative IL-1beta (U=448, p=0.07). Differences in the levels of TNF-alpha and IL-1ra were not statistically significant. Multiple regression analysis using TNM stage as a covariate, showed that gender was an independent predictor of post-operative IL-6 levels (p=0.04).

CONCLUSION

IL-1beta and IL-6 levels were significantly higher in men than in women. This provides evidence of a possible link between gender and cytokine levels in patients with colorectal cancer.