Immunologic effects of trauma and transfusion

Hemoglobin matters: Perioperative blood management for oncology patients

As the number of cancer cases rise each year in Canada, so does the number of surgical oncology cases. Surgery presents a unique and heightened stressor for the body already experiencing volatility from factors such as disease and treatments. Perioperative red blood cell (RBC) transfusions are critical to stabilize hemoglobin levels and correct anemia, as well as provide a buffer against anticipated intraoperative blood loss. Thoroughly examining and anticipating risk factors related to the potential need for perioperative blood transfusions is necessary to improve outcomes. Research evidence in recent years related to perioperative blood management of oncology patients has specifically recommended active, coordinated programs to reduce the need and amount of blood transfusions administered pre-, intra-, and post-surgery. Coordination between surgical oncologists and a local or provincial patient blood management (PBM) program is an important strategy that allows patients at risk of perioperative complications to be identified and receive early interventions and ongoing observation.

L’importance de l’hémoglobine : gestion périopératoire du sang pour les patients en oncologie

Au Canada, le nombre de cas de cancer augmente chaque année et, par conséquent, le nombre de patients en oncologie qui subissent une opération. La chirurgie cause un stress particulièrement intense à l’organisme déjà fragilisé par la maladie et les traitements. Les transfusions périopératoires de globules rouges sont essentielles pour stabiliser le taux d’hémoglobine et soigner l’anémie, ainsi que pour gérer la perte de sang attendue pendant l’opération. Il est nécessaire d’examiner en profondeur et d’anticiper les facteurs de risque associés aux transfusions sanguines périopératoires pour améliorer le devenir des patients. Ces dernières années, la recherche sur la gestion périopératoire du sang des patients en oncologie recommande tout spécialement la création de programmes d’intervention coordonnés pour réduire la nécessité et le nombre de transfusions sanguines administrées avant, pendant et après l’opération. Pour recenser les patients à risque de complications périopératoires et leur faire bénéficier d’interventions rapides et d’une observation continue, la bonne stratégie est de mettre en lien les chirurgiens oncologues avec un programme local ou provincial de conservation du sang.

Coronary artery bypass grafting is associated with immunoparalysis of monocytes and dendritic cells

Coronary artery bypass grafting (CABG) triggers a systemic inflammatory response that may contribute to adverse outcomes. Dendritic cells (DC) and monocytes are immunoregulatory cells potentially affected by CABG, contributing to an altered immune state. This study investigated changes in DC and monocyte responses in CABG patients at 5 time-points: admission, peri-operative, ICU, day 3 and day 5. Whole blood from 49 CABG patients was used in an ex vivo whole blood culture model to prospectively assess DC and monocyte responses. Lipopolysaccharide (LPS) was added in parallel to model responses to an infectious complication. Co-stimulatory and adhesion molecule expression and intracellular mediator production was measured by flow cytometry. CABG modulated monocyte and DC responses. In addition, DC and monocytes were immunoparalysed, evidenced by failure of co-stimulatory and adhesion molecules (eg HLA-DR), and intracellular mediators (eg IL-6) to respond to LPS stimulation. DC and monocyte modulation was associated with prolonged ICU length of stay and post-operative atrial fibrillation. DC and monocyte cytokine production did not recover by day 5 post-surgery. This study provides evidence that CABG modulates DC and monocyte responses. Using an ex vivo model to assess immune competency of CABG patients may help identify biomarkers to predict adverse outcomes.

Platelet vesicles are potent inflammatory mediators in red blood cell products and washing reduces the inflammatory phenotype

BACKGROUND

Studies suggest that washing red cell concentrates (RCCs) to remove soluble mediators and/or inflammatory components, such as extracellular vesicles (EVs), may lead to better clinical outcomes. This study tested the hypothesis that non-red blood cell (RBC) generated vesicles in RCC are potent inflammatory mediators in vitro and washing RCCs can reduce these vesicles and subsequently decrease the inflammatory activity of RCCs.

STUDY DESIGN AND METHODS

Sixteen RCCs were pooled and split into four groups based on pre-wash storage time (Day 2 or 14; n = 4/group). Each group was tested 24 hours and 7 days post-wash. Characteristics of RBCs and EVs, cytokines released by monocytes, and expression of human umbilical vein endothelial cells (HUVECs) adhesion molecules were assessed.

RESULTS

All RCCs meet quality standards for hemolysis, hematocrit, and hemoglobin. Washing did not remove residual platelets from RCCs but led to a significant reduction in platelet-EV count regardless of the group. Supernatant of RCCs washed on Day 14 and stored for 24 hours had significantly lower concentrations of RBC-EVs and white blood cell EVs compared to unwashed controls. Supernatant of unwashed RCCs showed higher production of inflammatory cytokines/chemokines MCP-1, IL-8, and TNF-α, and heightened expression of HUVEC VCAM-1, which were significantly reduced by washing. Spiking washed RCC supernatants with platelet-EVs showed significant increase in IL-8, MCP-1, VCAM-1, and E-selection in groups washed on Day 14.

CONCLUSIONS

Platelet-EVs in RCCs are associated with pro-inflammatory activity. As washing significantly reduced RCC immunomodulatory activity, implementation of this process may improve transfusion outcomes.