Metallic but not ceramic wear particles increase prostaglandin E2 release and interleukin-1beta gene expression in human blood monocytes in vitro.

In this study the potential of clinically relevant alumina ceramic and metal wear particles to induce an in vitro inflammatory response was assessed in human monocytes and lymphocytes isolated from healthy donors by measuring prostaglandin E2 (PGE2) levels and mRNA expression of various pro-inflammatory cytokines. Bacterial lipopolysaccharide (LPS) was used as positive control. LPS significantly increased PGE2 levels in the incubation medium of monocyte cultures after 24 h. Alumina had no effect on PGE2 production, whereas metals induced a concentration-dependent increase in PGE2 release, that was statistically significant at the dose of 0.1 mg/ml. In lymphocytes, LPS elicited a weak but significant increase in PGE2 release, whereas both alumina and metals did not modify PGE2 amounts at any of the concentrations tested. The gene expression of a number of pro- and anti-inflammatory cytokines was assessed in monocytes and lymphocytes exposed to LPS, 0.1 mg/ml alumina or 0.1 mg/ml metals for 24 h. In monocytes, LPS caused a 2-fold increase in interleukin-1beta (IL-1beta) mRNA levels. The exposure of monocytes to metals resulted in a selective increase in IL-1beta mRNA accumulation (+48% compared to control). By contrast, alumina did not modify IL-1beta mRNA levels. None of the test substances elicited any response on purified lymphocyte population. These findings suggest that PGE2 production and IL-1 mRNA expression are a reliable marker to study the pro-inflammatory effects of wear debris in vitro. The lower activity of alumina compared to metals suggests that the former should be preferred in implants for its favorable biological and mechanical behavior.

IL-10 and the cytokine network in the pathogenesis of human autoimmune hemolytic anemia.

In animal and human autoimmune hemolytic anemia (AIHA) immunologic tolerance loss against RBC self-antigens could be originated by several mechanisms: ignored self-antigens' epitopes, polyclonal lymphocyte activation, molecular mimicry between self- and foreign antigens, central or peripheral tolerance errors, or immunoregulatory disturbances including the alteration of a cytokine network. To identify the immunologic factors contributing to autoimmune onset and maintenance, several murine strains (such as NZB and NZB/NZW) that spontaneously develop a complex autoimmune syndrome, including AIHA, have been extensively studied. In human AIHA, the respective roles of IL-2, IL-4, IFN-gamma, IL-10, and IL-12 were investigated by examining the spontaneous and mitogen-induced (OKT3 or LPS) production of these cytokines. ELISA methods were used in PBMCs to evaluate whether the manipulation of IL-10/IL-12 balance can have an effect on the incidence of autoimmune diseases and whether this might be useful for the control of AIHA. Results affirmed that AIHA is a disease that exhibits an increased basal synthesis of IL-4 and decreased levels of IFN-gamma by AIHA PBMCs compared with controls and that there is a basal increase of Th2 cytokines. Th1-type cytokine decrease in the basal state occurred in parallel with an increase of constitutive IL-10 production and an IL-12 decrease. In conclusion, decreased production of Th1-type cytokines and the production of autoantibodies in AIHA may be secondary to the imbalance between IL-10 and IL-12, and the neutralization of IL-10 may be efficacious in diminishing the clinical pathology associated with Th2 subset prevalence. In the same way, the treatment with IL-12 could offer a second and independent level of blockade against the consequences of the overstimulation of B cells associated with AIHA.

IFN-gamma and TNF-alpha production in gamma-irradiated blood units by mononuclear cells and GVHD prevention.

Gamma-radiation of blood products is considered the mainstay of transfusion-associated graft-versus-host disease prevention. Previous studies have detected lymphocyte inhibition rate in blood components just one time after irradiation but there is evidence of cellular variability with production of cytokines at different storage time which could be related with irradiation activity and cellular damage repair. IFN-gamma, a Th1 cytokine, and TNF-alpha, a pro-inflammatory one, had a central role in the stimulation of cellular and inflammatory reactions. In this study whole blood was collected from five volunteer healthy donors and each donor bag was divided into two satellite bags: one of them was exposed to 137Cs-irradiation with a 2500 cGy dose. Samples for cytokine production, detected by ELISA methods, and proliferative response, evaluated by incorporation of H3 thymidine, were taken at the following storage time: 0, 24, 48, 72 and 96 h. The time-response curve of irradiated mononuclear cells from blood bags (BBMC) in mitogenic activation showed a time-related inhibition of cell proliferation with an enhanced response only after 24 h of storage and about 84% inhibition at 96 h. A similar pattern is follow by IFN-gamma production after OKT3 stimulation. TNF-alpha levels both in lipopolysaccharide stimulated or unstimulated cells were always high. This data suggest that BBMC cells maintain the ability to produce cytokines after gamma-radiation. On the ground of this study seems to be necessary to evaluate hypothetical risk associated with the administration of cytokine via irradiated blood components.

Thrombopoietin serum levels in patients with inflammatory bowel disease with and without previous thromboembolic events.

BACKGROUND/AIMS: Patients affected by inflammatory bowel disease frequently suffer from thromboembolic complications and mesenteric microvascular occlusion could be involved in the pathogenesis of inflammatory bowel disease. Increased platelet counts and abnormal platelet function seem to play a crucial role in determining the hypercoagulable state observed in inflammatory bowel disease. Thrombopoietin is considered the primary regulator of thrombopoiesis and recent studies have investigated the role of thrombopoietin in inflammatory bowel disease. However, the available data are not conclusive. The aim of this study was to assess thrombopoietin serum levels in inflammatory bowel disease patients according to platelet counts, disease activity and previous thrombotic events. METHODOLOGY: Seventy-one patients with inflammatory bowel disease [41 with ulcerative colitis and 30 with Crohn's disease] and 30 healthy controls were investigated. Eight (11%) inflammatory bowel disease patients had suffered previous thromboembolic complications, none had active thrombosis. Thrombopoietin serum levels were measured by ELISA. RESULTS: Mean thrombopoietin levels were significantly increased in inflammatory bowel disease patients with active disease compared to both healthy controls and patients with inactive disease. Platelet counts were significantly higher only in patients with active disease with respect to healthy subjects. No correlation was found between thrombopoietin levels and platelet counts in either controls or inflammatory bowel disease patients. No differences were found either in thrombopoietin levels or in platelet counts comparing inflammatory bowel disease patients with and without thromboembolic complications. CONCLUSIONS: Our data show elevated thrombopoietin levels in active inflammatory bowel disease. However, no correlation was found between platelet counts and thrombopoietin levels, supporting the hypothesis that other circulating factors than thrombopoietin interact in determining reactive thrombocytosis. Furthermore, thrombopoietin levels did not differ in inflammatory bowel disease patients with or without previous thromboembolic events. This finding could be probably explained by the lack of patients with active thrombosis at the moment of inclusion in the study.