Physiological heating augments the anti-inflammatory reactions during granulocyte/monocyte apheresis: A in vitro study.

Granulocyte and monocyte adsorptive apheresis (GMA), an effective therapy for inflammatory disorders, exerts an anti-inflammatory influence by utilizing the biological reaction between blood and cellulose acetate (CA) beads, which are the carriers of the GMA column. Although the biological reaction has an optimum temperature, blood contacts the CA beads below body temperature as GMA is performed in an extracorporeal circulation system. We investigated various soluble factors in blood treated with CA beads at 25°C and 37°C. Here, the optimal temperature for IL-1 receptor antagonist (IL-1ra) release induced by CA beads was 37°C, and IL-6 production from monocytic cells was inhibited by the addition of plasma prepared from the CA bead-treated blood at 37°C, rather than at 25°C. These results indicated that physiological heating of the apheresis carrier augmented the anti-inflammatory reaction in vitro. Thus, heating during GMA may be a new approach for augmenting clinical efficacy.

Cellulose acetate beads activate the complement system but inactivate the anaphylatoxins generated.

The generation of anaphylatoxins, particularly C5a, is important in extracorporeal circulation therapies such as granulocyte/monocyte apheresis, which activates the complement system and elevates C5a levels. However, no side effects of granulocyte/monocyte apheresis using cellulose acetate beads have been reported. To investigate the mechanism of complement activation, we prepared plasma from cellulose acetate bead-treated blood (P-CAB) and compared it with zymosan-activated plasma (ZAP). Anaphylaxis activity was measured by skin test, and the activity of carboxypeptidase, which inactivates C5a, was measured by colorimetric assay. Pro-carboxypeptidase R and neutrophil elastase concentrations were measured by enzyme-linked immunosorbent assay. Although C5a was generated in P-CAB, the anaphylaxis activity of P-CAB was lower than that of ZAP. Carboxypeptidase activity and pro-carboxypeptidase R levels were suppressed in P-CAB, but not in ZAP. Furthermore, neutrophil elastase levels increased in P-CAB. The decreases in carboxypeptidase activity and inactivation of anaphylatoxin were inhibited by a neutrophil elastase inhibitor. These results suggest that cellulose acetate beads initiate the activation of carboxypeptidase R via elastase release, thereby inducing the inactivation of anaphylatoxin.

Induction of Foxp3 expression in T cells by cellulose acetate beads in vitro.

Gene expression of transforming growth factor-beta (TGF-beta) is needed to induce expression of transcription factor forkhead box P3 (Foxp3), which is required for the development and function of regulatory T (Treg) cells. The number of circulating Treg cells and the level of Foxp3 expression increase during granulocyte and monocyte apheresis (GMA), a useful therapy for ulcerative colitis. However, the mechanism underlying GMA-induced Foxp3 expression is unknown. We found that the level of TGF-beta mRNA in peripheral blood mononuclear cells (PBMCs) was augmented just after treatment of peripheral blood with a GMA carrier, cellulose acetate beads, in vitro and that Foxp3 expression in PBMCs increased after culturing these cells for 5 days after the treatment. The augmentation of TGF-beta expression was observed in CD3(-) PBMCs but not in CD3(+) T cells. Furthermore, the increase in Foxp3 expression in T cells depended on co-culture with CD3(-) PBMCs. We conclude that cellulose acetate beads have an ability to induce Foxp3 expression in peripheral blood T cells via augmentation of TGF-beta expression in CD3(-) PBMCs.

Adsorption of Soluble Immunoglobulin-Type Adhesion Molecules to Cellulose Acetate Beads.

Circulating levels of soluble intercellular adhesion molecule-1 (sICAM-1) and vascular adhesion molecule-1 (sVCAM-1) are elevated in patients with inflammatory bowel disease. Cellulose acetate (CA) beads are used as carriers for granulocyte and monocyte (GM) adsorptive apheresis (GMA). We investigated the effect of CA beads on sICAM-1 and sVCAM-1 plasma concentrations in vitro. Because GM adsorption to CA beads increased with a rise in the incubation temperature in our previous study, peripheral blood was incubated with and without CA beads at 5, 25, 37, or 43 °C and plasma sICAM-1 and sVCAM-1 was measured. The sICAM-1 and sVCAM-1 concentrations in samples incubated with CA beads were significantly lower than those without CA beads at all four temperatures. However, no significant differences were observed both sICAM-1 and sVCAM-1 plasma levels at the four different temperatures after incubation with CA beads. These results suggest that independent of incubation temperature, sICAM-1 and sVCAM-1 are likely to adsorb CA beads. These molecules may be a new index for predicting the therapeutic effects of GMA.

Effect of Temperature on Granulocyte and Monocyte Adsorption to Cellulose Acetate Beads.

Granulocyte and monocyte (GM) adsorptive apheresis (GMA) is an effective therapy for inflammatory disorders including inflammatory bowel disease (IBD). During GMA, the blood of a patient with IBD passes through a column to contact cellulose acetate (CA) beads at a temperature below body temperature, likely close to room temperature. Here we investigated the effect of temperature on GM adsorption to CA beads in vitro. We incubated peripheral blood with and without CA beads at 5°C, 25°C, 37°C, and 43°C and calculated the ratios of adsorbed GMs. The ratios of adsorbed GMs increased as the temperature was raised. Additionally, we measured complement activation fragment concentrations. C3a and C5a concentrations also increased as the temperature was raised, and C5a concentrations had a positive correlation with the ratios of adsorbed GMs. These results suggest that warming the column during GMA might increase GM adsorption to CA beads, thereby enhancing the clinical efficacy of GMA.

Studies on the mechanisms of leukocyte adhesion to cellulose acetate beads: an in vitro model to assess the efficacy of cellulose acetate carrier-based granulocyte and monocyte adsorptive apheresis.

Granulocyte and monocyte adsorptive apheresis (GMA) using a column filled with cellulose acetate (CA) beads (carriers) has been associated with a significant clinical efficacy in patients with rheumatoid arthritis and ulcerative colitis. To obtain further understanding on the mechanisms of disease modification by cellulose acetate-carrier-based GMA, in the present study, we investigated the mechanisms of granulocyte and monocyte adhesion to CA beads following exposure of human peripheral blood to the carriers at 37 degrees C for up to 60 min under controlled conditions. Cellulose acetate beads selectively adsorbed granulocytes, monocytes. CD19+ (B cells) and CD56+ (NK cells) lymphocyte subpopulations. The granulocyte and monocyte adsorption was inhibited by heat-inactivated plasma and EDTA, indicating that the adsorption was plasma protein (immunoglobulin, complement) and calcium dependent. Accordingly, granulocyte and monocyte adsorption was markedly enhanced by coating the carriers with IgG. Similarly, C3b was adsorbed onto the CA beads as a marker of complement activation. The results indicated that IgG and active complement fragments mediated leukocyte adhesion to CA beads via the FcgammaR and/or leukocyte complement receptor like CR3. Additionally, CA beads induced loss of expression of TNF receptors on CD16- granulocytes and CD14+ monocytes, but not on CD3+ lymphocytes In conclusion, CA beads might be an appropriate biomaterial for inducing extracorporeal immunomodulation as a treatment for auto-immune diseases which are associated with pathological leukocyte activity.

Fabrication of 2D and 3D constructs from reconstituted decellularized tissue extracellular matrices.

We demonstrated a novel process to reconstitute a decellularized extracellular matrix (Recon-ECM) of heart and liver tissue using a combination of mechanical homogenization and enzymatic digestion. Such Recon-ECM was used as a biomaterial to produce flat or micro-patterned 2D films after crosslinking using replica molding. The mechanical properties of the resulting films were tuned by changing the type of crosslinking reagents. We also demonstrated the fabrication of mechanically robust 3D scaffolds by freeze-drying of the Recon-ECM solution. The porosity of the 3D scaffold was controlled by changing the concentration of the Recon-ECM. HepG2 cells were used to investigate the potential substrate of these engineered 2D patterned and 3D porous structures. The cell attachment, proliferation, and urea synthesis were evaluated, and the results indicate that the scaffold generated from Recon-ECM provides a biologically friendly environment for cells to grow. This method provides a new way to use decellularized ECM as a source of biomaterial to produce novel scaffolds with better controlled micro- and nano-scale structures, tunable physicochemical properties with desired biological functions.

Quantitative evaluation of fibroblast migration on a silk fibroin surface and TGFBI gene expression.

Cell migration plays important roles in natural processes involving embryonic development, inflammation, wound healing, cancer metastasis and angiogenesis. Cell migration on various biomaterials is also believed to improve the rate of wound healing and implant therapies in the tissue-engineering field. This study measured the distance traversed, or mileage, of mouse fibroblasts on a silk fibroin surface. Fibroblasts on the fibroin surface moved with better progress during 24 h than cells on collagen or fibronectin surfaces. Results obtained by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) revealed that fibroblasts on the fibroin surface expressed transforming growth factor ß-induced protein (TGFBI), which is an extracellular matrix (ECM) protein, stronger than on other surfaces in the early cell-culture stages. These results demonstrate that the fibroin surface shows higher potential to enhance cell migration and the production of ECM than a collagen or fibronectin surface.

Effect of RGDS-expressing fibroin dose on initial adhesive force of a single chondrocyte.

Initial chondrocyte-material interactions are important for cell behaviors such as proliferation, phenotypic expression and matrix synthesis. Previously, we showed that chondrocytes cultured in/on silk fibroin scaffolds proliferate without dedifferentiating into fibroblast-like cells and that RGDS sequences genetically interfused in the fibroin light chain protein enhance cartilage tissue formation. In the present study, the adhesive force of chondrocytes was measured on fibroin substrates containing RGDS-expressing fibroin molecules produced by transgenic silkworms at the different densities of 0, 0.6, 1.5 and 3.0 mol%. The degree of chondrocyte attachment to fibroin substrates increased with the number of RGDS-expressing fibroin molecules. Moreover, the adhesive force per unit spreading area of a single cultured chondrocyte exhibited a peak that was higher with increased RGDS concentrations. The results of this study indicate that the RGDS sequences genetically interfused in the fibroin light chain protein exert effects on chondrocytes' adhesive behavior and can enhance cartilage tissue organization.

Release of interleukin-1 receptor antagonist by combining a leukocyte adsorption carrier with ulinastatin.

Both granulocyte/monocyte adsorptive apheresis (GMA) and ulinastatin, a serine protease inhibitor, are reported to be effective in patients with ulcerative colitis; however, combination therapy with GMA and ulinastatin has not been attempted. Investigating the effect of ulinastatin on GMA is required for combination therapy since the inhibition of serine protease suppresses the reaction of GMA. To clarify the effects of ulinastatin on GMA, we investigated whether granulocyte adsorption to cellulose acetate beads (carriers for GMA) and interleukin-1 receptor antagonist (IL-1ra) release were inhibited by ulinastatin. Peripheral blood containing ulinastatin, a different serine protease inhibitor (gabexate mesilate), or signal-transduction inhibitors was incubated with cellulose acetate beads in vitro, and the ratios of adsorbed granulocytes and IL-1ra release were measured. Granulocyte adsorption and IL-1ra release were significantly suppressed with increasing gabexate mesilate concentrations; however, the adsorption was not significantly inhibited by ulinastatin. Furthermore, IL-1ra release was augmented by the addition of a high dose of ulinastatin or PD98059 as compared to a low dose. The activation levels of extracellular signal-regulated protein kinase may regulate IL-1ra release induced by the carrier, because both ulinastatin and PD98059 inhibit extracellular signal-regulated protein kinase. High concentrations of ulinastatin increased IL-1ra release without inhibiting granulocyte adsorption to cellulose acetate beads. This result warrants clinical trials of a combination of ulinastatin and GMA for the treatment of ulcerative colitis.

Biological effect of anaphylatoxin C5a on the generation of anti-inflammatory substances in leukocyte adsorption.

Anaphylatoxins, which are involved in both pro-inflammatory processes and a variety of anti-inflammatory effects, are produced during granulocyte and monocyte adsorptive apheresis. We noticed the anti-inflammatory effects of C5a, the strongest anaphylatoxin, in granulocyte and monocyte adsorptive apheresis. The aim of this study was to investigate the effect of C5a on interleukin-1 receptor antagonist (IL-1ra) and hepatocyte growth factor (HGF) generation in granulocyte and monocyte adsorption. Peripheral blood containing nafamostat mesilate as an endogenous complement activation inhibitor was divided into four groups: (1) no recombinant C5a added, no contact with cellulose acetate (CA) beads (control group); (2) no C5a added, contact with CA beads; (3) C5a added, no contact with CA beads; and (4) C5a added, contact with CA beads. After incubation, IL-1ra and HGF in plasma were measured. IL-1ra was significantly higher in group 3, in which only C5a was added in the absence of CA beads, compared to groups 2 (P < 0.01) and 4 (P < 0.05). HGF was significantly higher only in group 4, in which C5a was added in the presence of CA beads (P < 0.05), but did not increase in the absence of CA beads. C5a can directly induce IL-1ra generation without the granulocyte and monocyte adsorption stimuli to CA beads, but can synergistically induce HGF generation with the adsorption stimuli, indicating C5a has different effects on IL-1ra and HGF generation.

Complement activation is involved in biological responses to leukocyte adsorptive apheresis.

We examined the effects of complement activation on the biological responses of cellulose acetate (CA) beads. Peripheral blood containing the complement activation inhibitor nafamostat mesilate (NM) or heparin was incubated with CA beads in vitro. Thereafter, the fraction of adsorbed granulocytes as well as the generation of complement activation fragments (C3a and C5a) and interleukin 1 receptor antagonist (IL-1ra) were measured. Granulocyte adsorption, complement activation, and IL-1ra release were significantly inhibited in the presence of NM. Adsorption was significantly increased onto CA beads pretreated with plasma containing heparin even in the presence of NM and adding C3a or C5a enhanced IL-1ra release. These results suggested that bound complement fragment (e.g., C3b) on CA beads plays a central role in granulocyte adsorption to CA beads and that C3a and C5a augment the release of anti-inflammatory substances. We therefore conclude that complement activation is involved in these biological responses of leukocyte apheresis.