Plasma levels of interleukin-12 (IL-12), interleukin-18 (IL-18) and transforming growth factor beta (TGF-beta) in Plasmodium falciparum malaria

The interaction between pro- and anti-inflammatory cytokines such as interleukin 12 (IL-12), interleukin 18 (IL-18) and transforming growth factor beta (TGF-beta) may play an important role in malaria pathogenesis and outcome. IL-18 cooperates with IL-12 in the IFN-gamma production by T, B, and NK cells, and synergizes with IL-12 for IFN-gamma production by Th1 cells. Recently it has been demonstrated that these cytokines modulate the immunoresponse in Plasmodium falciparum malaria. The aim of this study was to measure the plasma levels of IL-12, IL-18 and TGF-beta in 105 African children with various degrees of malaria, and correlate the production of these cytokines with the severity of the disease. IL-12, IL-18 and TGF-beta levels were determined using enzyme-linked immunosorbent assay. The severity of malaria was established by parasitemia, clinical symptoms and haematological parameters. The levels of IL-12, IL-18 and TGF-beta were found to be significantly elevated (15.6 + / - 12.3, 22.7 + / - 13.8 pg/ml and 25.14 + / - 13.22 pg/ml respectively) in all of the children. IL-12 and IL-18 levels were significantly lower (13.2 + / - 5.53 and 21.5 + / - 10 pg/ml pg/ml) in children with severe disease, whereas the level of TGF-beta was higher (28.09 + / - 12.39 pg/ml). In contrast, IL-12 and IL-18 levels were found to be higher (17.32 + / - 7.8 pg/ml and 25.7 + / - 7.6 pg/ml) in patients with mild disease, whereas the level of TGF-beta was lower (20.92 + / - 12.76 pg/ml) compared to the severe malaria group. The correlation between IL-12 and IL-18 demonstrated a progressive relationship up to a value of IL-12 < 25 pg/ml, while IL-18 remained stable at higher levels of IL-12. An inverse correlation was found between IL-12 and TGF-beta up to a value of IL-12 < 30, after which the level of TGF-beta remained stable. This finding suggests that fine mechanisms regulate the interaction between IL-12, IL-18 and TGF-beta in the immune response to Plasmodium falciparum.     

Serum levels of interleukin-18 in patients with uncomplicated Plasmodium falciparum malaria

Interleukin (IL)-18, a newly discovered cytokine produced primarily by macrophages, has been shown to induce gamma interferon (IFN-gamma) production by natural killer cells, to induce the T helper type 1 response. To further elucidate the role of this cytokine in uncomplicated malaria caused by Plasmodium falciparum, serum levels of IL-18, and gamma interferon (IFN-gamma), determined by an immunoenzymatic assay, were analyzed in 40 adult patients, and in 15 healthy control subjects. A significant increase in serum levels of IL-18 was observed in patients with uncomplicated P. falciparum malaria on admission, whereas serum levels of IFN-gamma tended to increase although not significantly. Serum levels of IL-18 decreased three days later, but still remained significantly high, whereas IFN-gamma levels returned to normal levels compared to the controls. No significant correlation was found between parasitemia and serum levels of IL-18 and IFN-gamma. The increase of IL-18 levels during acute and recovery phases of uncomplicated P. falciparum malaria may reflect a proinflammatory role of IL-18 in these patients. An early and effective immune response regulated by proinflammatory Th1 cytokines, including tumor necrosis factor (TNF), interleukin (IL)-12, and possibly IFN-gamma may limit the progression from uncomplicated malaria to severe and life-threatening complications.     

Frequency of cytokine-producing CD4-CD8- peripheral blood mononuclear cells in patients with Plasmodium falciparum malaria.

The frequency of cytokine-producing CD4-/CD8- mononuclear cells was assessed in patients of different age groups (29 infants, aged 1-5 years; 30 schoolchildren, aged 6-14 years, 26 adults, aged > 15 years) with acute Plasmodium falciparum malaria, from Gabon. Fifteen patients were followed up before antimalarial treatment (day 0), during parasite clearance (day 3) and after resolution of parasitemia (day 10). By using flow cytometry for intracellular detection of cytokines, a striking expansion of CD4-/CD8- cells producing the type 1 cytokines interleukin (IL)-2-/interferon (IFN)-gamma+, IL-2+/IFN-gamma+ and IL-2+/IFN-gamma- was observed in adults as compared with children. Type 2 cytokine expression (IL-4+/IFN-gamma-, IL-13+/IFN-gamma-) and type 0 cells (IL-4+/IFN-gamma+, IL-13+/IFN-gamma+) were not significantly different between the three age groups. Patients with severe malaria had a significantly increased frequency of type 2 cytokine-producing CD4-/CD8- cells. Drug-induced clearance of parasitemia was characterized by a decrease of IL-2+/IFN-gamma- and type 2 cytokine expressing CD4-/CD8- cells and by a gradual increase of IL-10+/IFN-gamma- expression. The type 1/type 2 dichotomy observed within the CD4-/CD8- cell population is likely to be of significance in the host response against P. falciparum malaria.     

Plasmodium falciparum-specific interleukin-2 and tumor necrosis factor-alpha expressing-T cells are associated with resistance to reinfection and severe malaria in healthy African children

The frequency of P. falciparum-specific interleukin (IL)-2-, interferon (IFN)-gamma-, tumor necrosis factor (TNF)-alpha- and IL-10-expressing CD3+ cells was studied in healthy Gabonese children segregated according to their clinical presentation at admission to a longitudinal study of severe and mild malaria. The percentage of IL-2- and TNF-alpha- expressing P. falciparum-specific CD3+ cells was significantly higher in the children with prior mild malaria and less frequent reinfections compared to the children with prior severe malaria and more frequent reinfections. No differences were shown for P. falciparum-specific IFN-gamma and IL-10 expression within CD3+ cells and parasite-non-specific expression of IL-2, IL-4, IL-6, IL-10, IL-13, TNF-alpha, and IFN-gamma within the CD4+, CD8+, TCRgamma\delta+ CD3+ and CD94+ CD3- cell populations, indicating that immunological determinants regulating the susceptibility to malaria in age-matched children are parasite-specific. The ability of P. falciparum-specific T cells to mount a rapid IL-2 and TNF-alpha response might be of significance in preventing severe disease and reinfection.     

Serum evaluation of the balance between soluble interleukin-2 and interleukin-4 receptors

To elucidate the usefulness of the simultaneous analysis of the multiple kinds of soluble cytokine receptors, we determined both the soluble interleukin 2 receptor (sIL-2R, Th1-type cytokine receptor) and the soluble interleukin 4 receptor (sIL-4R, Th2-type cytokine receptor) levels in the sera of healthy subjects as reference values and preliminarily applied to evaluate the patients with diarrhea positive (D+) hemolytic uremic syndrome (HUS) as the diagnostic parameter of the severity. Both sIL-2R and sIL-4R levels in the sera of healthy children were significantly higher than those of healthy adults (p<0.01). The serum sIL-2R level of the patients with severe HUS (n=4) was higher than that of the patients with mild/moderate HUS (n=6) at the initial stage (p<0.01) or healthy children (n=51, p<0.01). Whereas, the serum sIL-4R level of both the severe and mild/moderate groups was lower than that of the healthy control children, although there was no significant difference among the three groups. Namely, the soluble receptor balance (sIL-2R/sIL-4R) in the patients with severe HUS may shift. We considered that the evaluation of the balance between soluble cytokine receptors might be informative for the evaluation of the immune states, as well as the conventional cytokine balance (Th1/Th2).     

Th1/Th2 cytokines and ICAM-1 levels post-liver transplant do not predict early rejection

Th1 derived cytokines IFN-gamma and IL-2, Th2 cytokine IL-4, and ICAM-1 have been implicated in liver allograft rejection. In order to determine whether monitoring of cytokine profiles during the first days post-liver transplant can predict early rejection we measured IFN-gg, IL-2, sIL-2 receptor, IL-4 and ICAM-1 in 22 patients, in plasma samples obtained within 4 h after liver perfusion (baseline) and between postoperative days (POD) 3-6. ICAM-1 and sIL-2R levels at POD 3-6 were significantly higher than at baseline but did not differ in presence or absence of rejection. Mean percentage increase of ICAM-1 levels was significantly lower in patients with Muromonab-C3 Orthoclone OKT3 (J.C. Health Care) (OKT3) whereas percentage increase of sIL-2R levels was higher in OKT3-treated patients. IFN-gamma levels at POD 3-6 increased from baseline while IL-4 levels were unchanged. Levels of IFN-gamma, IL-4 and their ratios did not correlate with rejection or immunosuppressive therapy. Thus, Th1/Th2 cytokine monitoring during the first week post-transplant does not predict early rejection and immunosuppressive therapy is the predominant factor affecting ICAM and sIL-2R levels after liver transplantation.     

Effect of a combination therapy between IL-12 and soluble IL-4 receptor (sIL-4R) on Candida albicans and herpes simplex virus type I infections in thermally injured mice

The effectiveness of a combination using IL-12 and soluble IL-4 receptor (sIL-4R) to treat severe infections of herpes simplex virus type 1 (HSV-1) and Candida albicans in thermally injured mice was investigated. Although sIL-4R decreased burn-associated type 2 T-cell responses, the effect of sIL-4R was minimal on the morbidity and mortality of thermally injured mice exposed to 250 times LD50 of HSV-1 or 10 times LD50 of C. albicans. Compared with 100% mortality in control mice, mortality for HSV-1 and C. albicans was 40 and 20%, respectively, in thermally injured mice that received IL-12 and sIL-4R in combination. After stimulation with anti-CD3 monoclonal antibody, splenic T cells from thermally injured mice exposed to large amounts of HSV-1 or C. albicans did not produce gamma interferon (IFN-gamma) into their culture fluids. However, IFN-gamma was produced by splenic T cells from thermally injured and infected mice treated with IL-12 and sIL-4R in combination. These results suggest that therapeutic treatment with a combination of IL-12 and sIL-4R may be effective by inducing type 1 T-cell responses in thermally injured mice exposed to large amounts of HSV-1 or C. albicans.     

The clinical significance of serum soluble interleukin 2 receptor (sIL-2R) concentration in lung cancer

The activated mononuclear cells can release a soluble form of interleukin 2 receptor (sIL-2R) in the blood. Serum sIL-2R level is a sensitive and quantitative marker of circulating peripheral blood mononuclear cell activation. This molecule acts as an antagonist of IL-2-mediated responses. The present study was carried out to analyze the circulating levels of sIL-2R in lung cancer in relation to the histological type of the tumour, clinical stage, response to therapy, time survival for patients. The study included 62 patients (30 SCLC, 32 NSCLC) and 10 healthy subjects as controls. SIL-2R serum levels were measured with a sandwich enzyme immunoassay using commercial kits (ENDOGEN). The mean serum values of sIL-2R were significantly higher in cancer patients than in controls (p=0.01). There was no significant difference in relation to tumour histological type. Within the NSCLC chemotherapy group, sIL-2R mean levels observed at the end of chemotherapy were higher in the progressing patients than in the responding patients. The metastatic patients had higher levels of sIL-2R than those with locally limited disease. In the case of SCLC classified to extensive disease mean levels of sIL-2R were higher than SCLC classified to limited disease. The mean serum values of sIL-2R were significantly higher in weight loss patients than no weight ones (p=0.03). Within NSCLC group there was a correlation between sIL-2R mean levels and the age of patients (p=0.04). In SCLC group there was a correlation between levels of sIL-2R and time survival for patients (p=0.009).     

Soluble interleukin-1 receptor type II, IL-18 and caspase-1 in mild cognitive impairment and severe Alzheimer's disease

In the present study, we have determined levels of soluble interleukin-1 (IL-1) receptor type II (sIL-1RII), interleukin-18 (IL-18) and caspase-1 in cerebrospinal fluid and serum from mild cognitive impairment patients that later progressed to Alzheimer's disease (AD) and severe AD patients. Previous studies have shown that a chronic local inflammatory process is a part of AD neuropathology. In this process, activated microglial production of IL-1 seems to play an important role. In a previous study, we have shown increased levels of sIL-1RII in CSF from AD patients in a mild-moderate disease stage. In the present study, we found no significant differences in CSF or serum levels of sIL-1RII in either mild cognitive impairment or advanced AD patients as compared to control subjects. Likewise, there was no significant difference between mild cognitive impairment and severe AD patients. The same was true for caspase-1 and IL-18 serum levels, whereas CSF levels of caspase-1 and IL-18 were below detection limits. Our data indicate that the IL-1 system is relatively intact in the early and late stages of AD.     

Circulating interleukin-18 and osteopontin are useful to evaluate disease activity in patients with tuberculosis

BACKGROUND: T helper type 1 (Th1) responses have been implicated in the protective immunity, pathophysiology and development of tuberculosis. However, it is still unclear which molecule(s) reflect disease activity in patients with tuberculosis. METHODS: By specific enzyme immunoassays, circulating interferon-gamma. (IFN-gamma), interleukin-12 (IL-12), IL-18 and osteopontin (OPN) were measured in 47 patients with pulmonary tuberculosis and 7 patients with miliary tuberculosis before anti-tuberculosis therapy, and also measured in 19 patients with tuberculosis before and after anti-tuberculosis therapy. RESULTS: Circulating IFN-gamma, IL-18 and OPN levels were significantly higher in patients with pulmonary tuberculosis than in healthy controls, while there was no significant difference in levels of circulating IL-12 between tuberculosis patients and controls. Circulating IFN-gamma, IL-12, IL-18 and OPN paralleled the extent of lung lesions, and circulating IFN-gamma, IL-18 and OPN paralleled the magnitude of fever in patients with pulmonary tuberculosis. Patients with miliary tuberculosis had extremely high levels of circulating OPN, IFN-gamma and IL-18. Circulating IL-18 and OPN were significantly decreased with anti-tuberculosis therapy, whereas circulating IL-12 and IFN-gamma were not. CONCLUSIONS: Among Th1 response associated molecules, circulating levels of IL-18 and OPN, but not IFN-gamma or IL-12, reflect disease activity in patients with tuberculosis.     

Interleukin-2 receptor positive cells and circulating soluble interleukin-2 receptors in patients with solid tumors are not correlated

Activated lymphocytes can release a soluble form of IL-2 receptor (sIL-2R), which retains the capacity to bind IL-2. Abnormally high values of sIL-2R have been observed in patients with advanced solid tumors. In an attempt to further understand the biological significance of sIL-2R in solid tumors, this study investigated the relation between sIL-2R and Tac-positive cells. sIL-2R serum levels and Tac-positive cells were determined in 18 patients with solid tumors metastatic, 108 non-metastatic. Tumor types were: breast 7; lung 6; colon 2; stomach 1; testis 1; larynx 1. No correlation was found between circulating sIL-2R values and Tac-positive cells, and there was no difference between Tac-positive cell mean number in patients with high and normal sIL-2R levels. These preliminary results suggest that different mechanisms are responsible for sIL-2R release in the blood and IL-2 receptor expression on the immune cell surface.     

Changes in cytokine production of breast cancer patients treated with interferons

A clinical randomized study was performed on advanced breast cancer patients who were treated by interferons (IFN) beta and gamma in combination with hormonotherapy (Megace or Tamoxifen). Cytokine levels (IL-1beta, IL-2, IL-6, TNF-alpha, IFN-gamma) and sIL-2R of individual patients before, during (3 months) and after (6 months) therapy were evaluated and correlated to clinical response according to UICC criteria (responder patients-partial or Complete Response versus non-responder patients-Stable/Progression). Decreases in IL-1beta, IL-6 and sIL-2R were associated with clinical response to therapy versus increases in their levels which corresponded to progression of disease. A significant and dramatic increase in IFN-gamma levels was associated with a favourable response to therapy in the IFNs-treated patients, mainly in the group of Tamoxifen. Baseline levels of sIL-2R and of IFN-gamma were prognostic of clinical response and were found to be the most sensitive cytokine parameters for defining the clinical utility of the combination of IFNs and hormonotherapy in breast cancer patients.     

Possible modulation by male sex hormone of Th1/Th2 function in protection against Plasmodium chabaudi chabaudi AS infection in mice

Zhang, Z.-H., Chen, L., Saito, S., Kanagawa, O., and Sendo, F. 2000. Possible modulation by male sex hormone of Th1/Th2 function in protection against Plasmodium chabaudi chabaudi AS infection in mice. Experimental Parasitology 96, 121-129. We examined the mortality, survival time, and parasitemia in interferon gamma receptor (IFN-gamma R)-deficient (IFN-gamma R(-/-)) and IL-4-deficient (IL-4(-/-)) mice infected with Plasmodium chabaudi AS and compared them with the wild type counterparts (IFN-gamma R(+/+) and IL-4(+/+), respectively). (1) Mortality was higher and survival time was shorter in males of both IFN-gamma R(-/-) and IL-4(-/-) mice infected with P. chabaudi AS, compared with their wild type counterparts, whereas such a difference was not observed in female mice. (2) These differences between males and females were not observed when male mice were castrated; however, female castration had no effect on the data. (3) The rate of parasitemia in both male and female IFN-gamma R(-/-) and IL-4(-/-) mice was higher at some points during the observation than in the wild type counterparts. (4) These results on susceptibility vs resistance to P. chabaudi AS infection can be explained partially by the levels of expression of Th1/Th2 cytokine and chemokine mRNAs in the spleen cells of the infected mice. These results suggest that male sex hormones modulate the function of Th1/Th2 cells and that these T cells counteract the activity of these hormones in protection against P. chabaudi AS infection in mice.     

Therapeutic protective effects of IL-12 combined with soluble IL-4 receptor against established infections of herpes simplex virus type 1 in thermally injured mice.

The effect of combination therapy between IL-12 and soluble IL-4R (sIL-4R) on the established infection of HSV-1 in thermally injured mice (TI mice) was investigated. All of the TI mice infected with lethal amounts of HSV-1 died when IL-12 was given therapeutically at a dose of 500 U/mouse. However, 80% of these mice treated prophylactically with IL-12 survived compared with 0% survival of the same mice treated with saline. The therapeutic administration of IL-12 to TI mice currently infected with HSV-1 caused an 80% survival of these mice when the treatment was combined with sIL-4R. Although IL-12 did not stimulate IFN-gamma production in cultures of splenic T cells from TI mice, IFN-gamma was produced by stimulation with IL-12 when the producer cells were prepared from TI mice that had been treated previously with sIL-4R. After stimulation with anti-CD3 mAb, splenic T cells from TI mice with the established infection of HSV-1 produced IL-4 into their culture fluids. However, IL-4 was not produced by splenic T cells that were prepared from the same infected mice treated with IL-12 and sIL-4R in combination. The results obtained herein indicate that the efficacies of the combination therapy against the established infection of HSV-1 may result from the IFN-gamma production stimulated by IL-12 in TI mice that are treated with sIL-4R for reducing burn-associated type 2 T cell responses.     

The role of IL-18 in blood-stage immunity against murine malaria Plasmodium yoelii 265 and Plasmodium berghei ANKA

A possible protective role of IL-18 in host defense against blood-stage murine malarial infection was studied in BALB/c mice using a nonlethal strain, Plasmodium yoelii 265, and a lethal strain, Plasmodium berghei ANKA. Infection induced an increase in mRNA expression of IL-18, IL-12p40, IFN-gamma, and TNF-alpha in the case of P. yoelii 265 and an increase of IL-18, IL-12p40, and IFN-gamma in the case of P. berghei ANKA. The timing of mRNA expression of IL-18 in both cases was consistent with a role in the induction of IFN-gamma protein expression. Histological examination of spleen and liver tissues from infected controls treated with PBS showed poor cellular inflammatory reaction, massive necrosis, a large number of infected parasitized RBCs, and severe deposition of hemozoin pigment. In contrast, IL-18-treated infected mice showed massive infiltration of inflammatory cells consisting of mononuclear cells and Kupffer cells, decreased necrosis, and decreased deposition of the pigment hemozoin. Treatment with rIL-18 increased serum IFN-gamma levels in mice infected with both parasites, delayed onset of parasitemia, conferred a protective effect, and thus increased survival rate of infected mice. Administration of neutralizing anti-IL-18 Ab exacerbated infection, impaired host resistance and shortened the mean survival of mice infected with P. berghei ANKA. Furthermore, IL-18 knockout mice were more susceptible to P. berghei ANKA than were wild-type C57BL/6 mice. These data suggest that IL-18 plays a protective role in host defense by enhancing IFN-gamma production during blood-stage infection by murine malaria.     

Factors associated with inflammation markers, a cross-sectional analysis

Epidemiological studies have reported associations between circulating inflammation markers and risk of chronic diseases. It is of interest to examine whether risk factors for these diseases are associated with inflammation. We conducted a cross-sectional analysis to evaluate whether reproductive and lifestyle factors and circulating vitamin D were associated with inflammation markers, including C-reactive protein, cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-12p70, IL-13, TNFα), and cytokine modulators (IL-1RA, sIL-1RII, sIL-2Ra, sIL-4R, sIL-6R, sTNF-R1/R2), among 616 healthy women. We confirmed associations of several inflammation markers with age and BMI. We also observed significantly higher levels of certain inflammation markers in postmenopausal vs. premenopausal women (TNFα, sIL-1RII, sIL-2Ra), with increasing parity (IL-12p40), and with higher circulating 25(OH) vitamin D (IL-13) and lower levels among current users of non-steroidal anti-inflammatory drugs (NSAIDs) (IL-1β, IL-2, IL-10, IL-12p70, and IL-12p40), current smokers (IL-4, IL-13, IL-12p40), and women with a family history of breast or ovarian cancer (IL-4, IL-10, IL-13). Our findings suggest that risk factors for chronic diseases (age, BMI, menopausal status, parity, NSAID use, family history of breast and ovarian cancer, and smoking) are associated with inflammation markers in healthy women.     

Soluble IL-2 receptor as an agent of serum-mediated suppression in human visceral leishmaniasis

In visceral leishmaniasis (VL), patient's lymphocytes are not activated by leishmania Ag stimulation, and their sera exhibit a potent nonspecific suppressive effect on the responses of normal lymphocytes. Sera were obtained from 33 VL patients, eight patients with subclinical VL, and from 27 normal volunteers. Only sera from VL patients markedly reduced Con A-induced lymphocyte proliferative responses, as well as IL-2 or IFN-gamma production by normal lymphocytes. Addition of exogenous human rIL-2 to cultures containing VL patient sera partially reversed the normal lymphocyte proliferative capacity and restored IFN-gamma production. This phenomenon was consistent with the presence of greatly elevated levels of soluble IL-2R (sIL-2R) in VL patients' sera (4299 +/- 2351 U/ml), well above those of normal sera (180 +/- 94 U/ml), or of sera from patients with subclinical leishmania infection without immunosuppression (1002 +/- 281 U/ml). Furthermore, the removal of sIL-2R reduced VL serum suppressive activity as evaluated by effects on IL-2 and on IFN-gamma production. These data suggest the participation of high levels of sIL-2R in the serum-mediated suppression in VL.     

Severe malarial anemia associated with increased soluble Fas ligand (sFasL) concentrations in Gabonese children

To investigate if severe malarial anemia is associated with specific cytokine overproduction, we evaluated serum levels of soluble Fas ligand (sFasL), tumor necrosis factor (TNF-alpha) and interleukin-10 (IL-10) from three groups of young children with Plasmodium falciparum infection (asymptomatic cases, uncomplicated malaria cases and severe malarial anemia cases), in a hyperendemic area of Gabon. In uncomplicated cases, only TNF levels were significantly (p < 0.001) increased in comparison to asymptomatic cases with P. falciparum infection. High levels of sFasL, TNF-alpha and IL-10 were associated with low hemoglobin concentrations, sFasL levels were significantly higher in children with severe malarial anemia (p < 0.001) as compared to both other groups. The parasite density was positively correlated with IL-10, TNF-alpha and sFasL levels. TNF-alpha and sFasL, but not IL-10 or parasitemia, were independent predictors of hemoglobin concentrations. These results suggest that, in malaria, a specific dysregulation of the cytokine balance may lead to complications such as severe anemia.     

Shedding of Endogenous Interleukin-6 Receptor (IL-6R) Is Governed by A Disintegrin and Metalloproteinase (ADAM) Proteases while a Full-length IL-6R Isoform Localizes to Circulating Microvesicles

Generation of the soluble interleukin-6 receptor (sIL-6R) is a prerequisite for pathogenic IL-6 trans-signaling, which constitutes a distinct signaling pathway of the pleiotropic cytokine interleukin-6 (IL-6). Although in vitro experiments using ectopically overexpressed IL-6R and candidate proteases revealed major roles for the metalloproteinases ADAM10 and ADAM17 in IL-6R shedding, the identity of the protease(s) cleaving IL-6R in more physiological settings, or even in vivo, remains unknown. By taking advantage of specific pharmacological inhibitors and primary cells from ADAM-deficient mice we established that endogenous IL-6R of both human and murine origin is shed by ADAM17 in an induced manner, whereas constitutive release of endogenous IL-6R is largely mediated by ADAM10. Although circulating IL-6R levels are altered in various diseases, the origin of blood-borne IL-6R is still poorly understood. It has been shown previously that ADAM17 hypomorphic mice exhibit unaltered levels of serum sIL-6R. Here, by quantification of serum sIL-6R in protease-deficient mice as well as human patients we also excluded ADAM10, ADAM8, neutrophil elastase, cathepsin G, and proteinase 3 from contributing to circulating sIL-6R. Furthermore, we ruled out alternative splicing of the IL-6R mRNA as a potential source of circulating sIL-6R in the mouse. Instead, we found full-length IL-6R on circulating microvesicles, establishing microvesicle release as a novel mechanism for sIL-6R generation.     

Cytokines in Gaucher's disease.

Gaucher's disease (GD) is characterized by hepatosplenomegaly, bone marrow infiltration, osteonecrosis, which may all be associated with the presence of pathological macrophages that contain undegraded glycosphingolipids. Levels of serum cytokines, which are soluble products of mononuclear phagocytes (MNP), were evaluated in 24 GD patients. Levels of interleukin-1beta (IL-1beta), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and soluble interleukin-2 receptor (sIL-2R) in GD patients were significantly higher than in normal controls. We attempted to correlate cytokine levels with disease severity. Type I GD patients with more severe clinical manifestations had significantly higher levels of IL-1beta, IL-1Ra and IL-6, relative to type I patients with milder disease. Three patients homozygous for the 1448C mutation with neuropathic type III disease, had significantly higher levels of sIL-2R than type I patients or controls. We speculate that cytokine over-expression may relate to the pathophysiology of some of the clinical manifestations of GD. Thus, the elevated IL-1beta, TNF-alpha and IL-6 levels may induce the bone manifestations, the neutrophil chemotaxis and the increased incidence of hyper-gammaglobulinemia present in GD patients.