Effects of IL-1β, IL-6 and IL-8 on erythrocytes, platelets and clot viscoelasticity

Abstract

Complex interactions exist between cytokines, and the interleukin family plays a fundamental role in inflammation. Particularly circulating IL-1β, IL-6 and IL-8 are unregulated in systemic and chronic inflammatory conditions. Hypercoagulability is an important hallmark of inflammation, and these cytokines are critically involved in abnormal clot formation, erythrocyte pathology and platelet hyper-activation, and these three cytokines have known receptors on platelets. Although these cytokines are always unregulated in inflammation, we do not know how the individual cytokines act upon the structure of erythrocytes and platelets, and which of the viscoelastic clot parameters are changed. Here we study the effects of IL-1β, IL-6 and IL-8 at low physiological levels, representative of chronic inflammation, by using scanning electron microscopy and thromboelastography. All three interleukins caused the viscoelastic properties to display an increased hypercoagulability of whole blood and pathology of both erythrocytes and platelets. The most pronounced changes were noted where all three cytokines caused platelet hyper-activation and spreading. Erythrocyte structure was notably affected in the presence of IL-8, where the morphological changes resembled that typically seen in eryptosis (programmed cell death). We suggest that erythrocytes and platelets are particularly sensitive to cytokine presence, and that they are excellent health indicators.

Figure 1. The intricate relationship between inflammation and hyper-coagulation.

This diagram focuses on the bidirectional relationship between inflammation and coagulation and the role that increased pro-inflammatory cytokines in both acute and chronic systemic inflammation plays in the activation of the coagulation system.

Figure 2

(A) A low magnification to show overall view with RBCs and a platelet with slight pseudopodia formation due to contact activation. (B) Representative RBC from a healthy individual; (C) high magnification of RBC membrane; (D) platelet showing slight pseudopodia formation due to contact activation. Micrographs were taken at 1 kV using a crossbeam 540 Zeiss scanning electron microscope. No changes were done on actual figures and color enhancement was done using Adobe®Photoshop CS6® version 13.0 × 64.

Figure 3

(A,B) Representative RBCs and platelet clumps from a healthy individual, after whole blood was exposed to IL-1β; (C) high magnification of RBC membrane; (D) Platelet that shows spreading and hyper-activation. Micrographs were taken at 1 kV using a crossbeam 540 Zeiss scanning electron microscope. No changes were done on actual figures and color enhancement was done using Adobe®Photoshop CS6® version 13.0 × 64.

Figure 4

(A,B) Representative RBCs and platelet clumps from a healthy individual, after whole blood was exposed to IL-6; (C) high magnification of RBC membrane; (D) Platelet that shows spreading and hyper-activation. Micrographs were taken at 1 kV using a crossbeam 540 Zeiss scanning electron microscope. No changes were done on actual figures and color enhancement was done using Adobe®Photoshop CS6® version 13.0 × 64.

Figure 5

(A,B) Representative RBCs and platelet clumps from a healthy individual, after whole blood was exposed to IL-8; eryptotic cells indicated with arrows. (C) High magnification of RBC membrane, showing ultrastructural changes; (D) Platelet that shows hyper-activation. Micrographs were taken at 1 kV using a crossbeam 540 Zeiss scanning electron microscope. No changes were done on actual figures and color enhancement was done using Adobe®Photoshop CS6® version 13.0 × 64.

Figure 6. Micrographs from inflammatory diseases where IL-1β, IL-6 and IL-8 upregulation plays a fundamental role in the pathogenesis and hypercoagulability of the diseases.

(A) Alzheimer’s disease; (B) Parkinson’s disease; (C) type 2 diabetes; (D) rheumathoid arthritis. Micrographs were taken at 1 kV using a crossbeam 540 Zeiss scanning electron microscope. No changes were done on actual figures and color enhancement was done using Adobe®Photoshop CS6® version 13.0 × 64.