Circulating Th1 and Th2 cytokines in patients with hepatitis C virus infection.

The imbalance of T-helper (Th) lymphocyte cytokine production may play an important role in immunopathogenesis of persistent hepatitis C virus (HCV) infection. To know whether an imbalance between Th1 and Th2 cytokines is present in chronic HCV infection, serum levels of Th1 cytokines, interferon gamma (IFN-gamma) and interleukin (IL)-2, and Th2 cytokines, IL-4 and IL-10, were measured using enzyme-linked immunosorbent assay in this study. Eighteen individuals with chronic HCV infection, 11 healthy subjects as normal controls and 10 chronic HBV infected patients as disease controls were observed. The results showed that the levels of Th2 cytokines (IL-4 and IL-10) were significantly increased in chronic HCV infected patients compared with normal controls (IL-4: 30.49+/-17.55 vs. 14.94+/-13.73, pg/ml, P<0.025; IL-10: 50.30+/-19.59 vs. 17.87+/-9.49, pg/ml, P<0.001). Similarly, the levels of Th1 cytokine, IL-2, was also elevated in individuals with chronic HCV infection when compared with normal controls (IL-2: 118.53+/-95.23 vs. 61.57+/-28.70, pg/ml, P<0.05). However, Th1 cytokine IFN-gamma level was not significantly changed during HCV infection (IFN-gamma: 28.09+/-15.65 vs. 24.10+/-15.61, pg/ml, P>0.05). Furthermore, the elevated levels of Th2 cytokines are greater than Th1 cytokines in HCV infection. Thus, the study indicates that an enhanced Th2 responses are present during chronic HCV infection, which may partly be responsible for the persistence of HCV infection.     

Elevated levels of interleukin-13 and IL-18 in patients with dengue hemorrhagic fever

Interleukin (IL)-13 is produced by T helper 2 (Th2)-type cells and inhibits the production of proinflammatory cytokines by activated monocytes, while IL-18 is a pleiotropic cytokine that induces interferon-gamma and plays an important role in the development of Th1-type cells. Role of the shift from a Th1-type response to Th2-type has been suggested in the pathogenesis of dengue hemorrhagic fever (DHF). This study was undertaken to investigate the possible protective/pathogenic role of IL-13 and IL-18 in patients with DHF. Sera were collected from a total of 84 patients with various grades of dengue illness and 21 normal healthy controls and tested for IL-13 and IL-18 levels using commercial enzyme-linked immunosorbent assay kits. The results showed that very low levels of IL-13 (4+/-3 pg ml(-1)) and IL-18 (15+/-4 pg ml(-1)) were detected in the sera of healthy controls. In dengue patients, the levels of IL-13 and IL-18 were the highest in the patients with DHF grade IV (205+/-103 pg ml(-1) and 366+/-155 pg ml(-1), respectively) and the lowest in patients with dengue fever (22+/-12 pg ml(-1) and 76+/-50 pg ml(-1), respectively). Both the cytokines appeared (IL-13=20+/-11 pg ml(-1) and IL-18=70+/-45 pg ml(-1)) during the first 4 days of illness and reached peak levels (IL-13=204+/-96 pg ml(-1) and IL-18=360+/-148 pg ml(-1)) by day 9 onwards. The presence of high levels of IL-13 and IL-18 during severe illness and late phases of the disease suggests that both of these cytokines may contribute to the shift from a Th1- to Th2-type response and thus to the pathogenesis of DHF.     

Interleukin-18 enhances HIV-1 production in a human chronically-infected T cell line (H9-V)

Interleukin-18 (IL-18) is a recently identified immunoregulatory cytokine expressed by activated macrophages, that induces production of interferon-gamma (IFN-gamma) and Th-1 development. Recently some investigators reported controversial in vitro data on IL-18 stimulation of HIV-1 replication in several cell lines. In the present study the effect of IL-18 on HIV replication in a human chronically HIV-1-infected lymphocytic T cell line (H9-V) was investigated. HIV-1 replication was determined by an immunoassay method in order to evaluate the content of p24 antigen in the cell culture supernatants. Stimulation of H9-V cells with IL-18 resulted in increased production of p24, especially at concentrations of 0.01 microg ml(-1) and 0.10 microg ml(-1). Moreover a significant and persistent IL-18 stimulation of HIV-1 replication was observed at a concentration of 0.01 microg ml(-1) during a 7-day period. Pre-treatment of IL-18 with a specific neutralizing monoclonal antibody significantly reduced HIV-1 replication. These experiments show that IL-18 promotes the increase of HIV-1 replication in human chronically-infected lymphocytic T cells and confirm the role of IL-18 as a proimflammatory cytokine in stimulating and maintaining HIV-1 replication during the course of the disease. In a successive set of experiments, since one of the main activities of IL-18 is the induction of IFN-gamma, we evaluated the effect of this biological modifier on H9-V cells. In particular, IFN-gamma shows a significant effect on cell replication and on reduction of CD4 and CD71 surface expression.     

Cervico-vaginal dysplasia--papillomavirus-induced and HIV-1 infection: role of correlated markers for prognostic evaluation

Sexually-transmitted diseases (STD) can facilitate the progression of HIV-1 infection. Among them, as we have previously demonstrated, cervico-vaginal dysplasia-papillomavirus (HPV)-induced, together with HSV-2 co-infection, seems to be correlated with a more evident immunodepression in HIV-positive women, compared with other sexually transmitted diseases. Here we have analysed some of the main correlated markers of HIV-1 infection progression: CD4 + T lymphocyte concentration, CD4 +/CD8 + T cells ratio, HIV-1 RNA loads and haemoglobin (Hb) concentration in 30 HIV-1 positive women co-infected with HPV, and suffering from cervico-vaginal dysplasia, in different stages. In particular, we noticed a positive correlation, evaluated by Spearman's test, between the degree of progression of dysplastic stages (CIN1 --> 3) until invasive carcinoma (IC) and HIV-1 RNA loads (C(s) = +0.78; p < 0.001), and in contrast, a negative correlation between the same stages of progression and respectively CD4 + T cell concentration (C(s) = -0.54; p = 0.01), ratio (C(s) = - 0.63; p = 0.002) and Hb concentration (C(s) = -0.85; p < 0.001). In conclusion, it is important to underline that low levels of Hb generally paralleled the degree of immunodepression. In fact CD4 + T cell levels and ratio positively correlated with Hb concentrations respectively, with C(s) = + 0.83; p < 0.001 and C(s) = + 0.90; p < 0.001. Finally, the most efficacious antiretroviral combined therapy (HAART = Highly Active Antiretroviral Therapy) can improve the above described laboratory parameters in HIV-1/HPV co-infected women and seems to prevent the progression of CIN1 to the following stages of the dysplastic disease.     

IL-10 and IL-12 are the main regulatory cytokines in visceral leishmaniasis

Visceral leishmaniasis (VL) is characterized by the absence of cytokines such as IFN-gamma and IL-12. Cure of VL is associated with a restoration of the ability to make these cytokines. The aim of the present study was to evaluate the role of IL-12 in the recovery of the ability to produce IFN-gamma and to test whether or not IL-4 IL-10 and/or TGF-beta could suppress IFN-gamma production by PBMC from treated VL patients. High stimulation index (SI) of proliferation was observed in PBMC from subjects stimulated with Leishmania chagasi antigen (181+/-83). Neutralizing IL-12 inhibited lymphoproliferation [stimulation index (SI) of 210+/-114 to 1+/-0.6 (P<0.01)] and/or the production of IFN-gamma [2792+/-402 pg/ml to 407+/-449 pg/ml (P<0.01)]. Recombinant IL-10 abrogated the lymphoproliferation (SI=2+/-3) while recombinant IL-4 or TGF-beta had no effect on this response (147+/-22 and 194+/-12 respectively). IFN-gamma was high when PBMCs were stimulated with L. chagasi (873+/-400 pg/ml) and this was abrogated by the addition of IL-10 (5+/-2 pg/ml). In contrast neither IL-4 or TGF-beta suppressed IFN-gamma production (837+/-244 pg/ml and 759+/-523 pg/ml). These results indicate that IL-12 plays an important role in the ability of treated VL patients to make IFN-gamma and that IL-10 but not IL-4 or TGF-beta inhibits this response.     

Identification of a novel cytokine, ML-1, and its expression in subjects with asthma

A novel gene, designated ML-1, was identified from a human genomic DNA clone and human T cell cDNA sequences. The second exon of ML-1 gene shares significant sequence identity with the gene encoding IL-17 (IL-17). ML-1 gene expression was up-regulated in activated PBMCs, CD4(+) T cells, allergen-specific Th0, Th1, and Th2 clones, activated basophils, and mast cells. Increased expression of the ML-1 gene, but not IL-17, was seen following allergen challenge in four asthmatic subjects, suggesting its role in allergic inflammatory responses. ML-1 from transiently transfected COS-7 cells was able to induce gene expression and protein production for IL-6 and IL-8 (at 10 ng/ml of ML-1: for IL-6, 599.6 +/- 19.1 pg/ml; for IL-8, 1724.2 +/- 132.9 pg/ml; and at 100 ng/ml of ML-1: for IL-6, 1005.3 +/- 55.6 pg/ml; for IL-8, 4371.4 +/- 280.5 pg/ml; p < 0.05 for both doses vs baseline) in primary bronchial epithelial (PBE) cells. Furthermore, increased expression of ICAM-1 was found in ML-1-stimulated PBE cells (mean fluorescence intensity (MFI) = 31.42 +/- 4.39 vs baseline, MFI = 12.26 +/- 1.77, p < 0.05), a functional feature distinct from IL-17 (MFI = 11.07 +/- 1.22). This effect was not inhibited by a saturating amount of IL-17. These findings demonstrate that ML-1 is a novel cytokine with a distinct function, and suggest a different receptor for ML-1 on PBE cells.     

Serum levels of interleukin-13 and interferon-gamma from adult patients with asthma in Mysore

Serum protein analysis for noninvasive quantification of airway inflammation in asthma is a promising research tool in the field of lung diseases. Cytokines are believed to have major role in inflammatory process of the airways of the lung. There is an imbalance between T-helper (Th)-2 cells, which secrete interleukin (IL)-4 and interleukin (IL)-13, and Th1 cells, which secrete interferon (IFN)-gamma in asthma. To test the hypothesis that serum IL-13 and IL-4 levels may be elevated whereas IFN-gamma would be decreased in this cohort of patients, a property that could make them possible candidate biomarkers in determining asthma occurrence and severity, we measured concentrations of IL-4, IL-13 and IFN-gamma in serum samples of 88 subjects (44 normal, 12 with mild asthma, 16 with moderate asthma, and 16 with severe asthma). Serum Levels of IL-4, IL-13, and IFN-gamma were determined by an enzyme-linked immune-sorbent assay (ELISA). Median serum level of IFN-gamma in asthmatic patients was 8.0pg/ml, while it was 11.4pg/ml in healthy controls. However, the difference was not significant. Among the different age groups in whom IFN-gamma was assessed, the highest median value in both cases and controls was observed in the age group of 31-40years. The median serum level of IL-13 was 40.0pg/ml in asthmatic patients and 58.25pg/ml in healthy controls. The difference was not significant. On subgroup analysis, no significant difference of IFN-gamma and IL-13 between asthma of different severities was observed. The study also revealed nonsignificant difference of serum cytokines with the duration of asthma, number of allergens, and severity of sensitization. Normal serum levels of IFN-gamma and IL-13 in asthmatic patients suggest their neutral role in the inflammatory process; however, more studies are required to establish the effect of these cytokines in adulthood asthma in different ethnic populations.     

CXCL10/IP-10 release is induced by incubation of whole blood from tuberculosis patients with ESAT-6, CFP10 and TB7.7

IFN-gamma responses to Mycobacterium tuberculosis specific antigens are used as in vitro diagnostic tests for tuberculosis infection. The tests are sensitive and specific for latent and active tuberculosis disease, but sensitivity may be reduced during immunosuppression. The objective of the study was to explore new ways to improve the diagnosis of tuberculosis infection using CXCL10 and IL-2 as alternative markers to IFN-gamma. CXCL10, IL-2, and IFN-gamma responses to stimulation with ESAT-6/CFP10/TB7.7 were assessed in 12 Quantiferon positive, 8 Quantiferon negative tuberculosis patients and 11 Quantiferon negative controls. CXCL10 and IL-2 were determined by multiplex and IFN-gamma by the Quantiferon ELISA. The median antigen specific CXCL10, IFN-gamma, and IL-2 responses in patients with tuberculosis were 870 pg/ml (range 261-1576 pg/ml), 217 pg/ml (81-1273 pg/ml), 59 pg/ml (14-276 pg/ml) respectively, and the CXCL10 responses were significantly higher than any of the other cytokines measured (p=0.001). In 4/7 individuals with a negative (n=6) or indeterminate (n=1) Quantiferon test, antigen specific CXCL10 responses were detectable at high levels ranging from 196-532 pg/ml. In conclusion CXCL10 was strongly induced after M. tuberculosis specific stimulation and sensitivity appeared superior to the Quantiferon test. Our findings suggest that CXCL10 may serve as an alternative or additional marker for the immunodiagnosis of tuberculosis.     

TH1/TH2 cytokine levels as an indicator for disease progression in human immunodeficiency virus type 1 infection and response to antiretroviral therapy

A recent theory stipulates that during the course of HIV infection, there is a shift in immune response from T-helper 1 to T-helper 2 responses, characterised by elevated secretions of relevant cytokines. Cytokine profiles of 15 asymptomatic (treatment na?ve) and 26 symptomatic (undergoing treatment) HIV-1 patients was determined to investigate the validity of this theory. HIV-1 RNA was quantified using the COBAS TaqMan HIV-1 test, CD4 T-cell counts with the FACSCalibur flow cytometer and IL-1, IL-4, IL-6, IL-10 and IFN-gamma cytokine levels by ELISA method. The asymptomatic group had significantly higher RNA levels (p-value; 0.000006) and lower CD4 T-cell counts than the symptomatic group indicating ongoing disease progression in the absence of antiretroviral treatment and a positive response to HIV treatment by the symptomatic group. IL-1, IL-4 and IFN-gamma were undetectable in most study subjects. IL-10 and IL-6 levels was relatively lower in the asymptomatic group (mean value; 206.352 pg/ml, 10.516 pg/ml) than the symptomatic group (mean value; 417.539, 18.387 pg/ml). Lower levels of proinflammatory cytokines (IL-1, IFN-gamma) in both study groups and elevated levels of anti-inflammatory cytokine IL-10, confirms that there is a shift in immune response as HIV infection progress to AIDS. In addition, the presence of a progressive trend of anti-inflammatory cytokine, IL-10 and proinflammatory cytokine, IL-6 in 12 symptomatic patients tested 3 months after antiretroviral therapy indicates an attempt by antiretrovirals to restore immune function.     

Serum levels of TNF-alpha,sIL-2R,IL-6, and IL-8 are increased and associated with elevated lipid peroxidation in patients with Behçet's disease

AIM: Behçet''s disease (BD) is asystemic immunoinflammatory disorder and the aetiopathogenesis is to be specified. Cytokines play a role in immune response and in many inflammatory diseases. The aim of this case-control study is to investigate serum pro-inflammatory cytokine tumour necrosis factor (TNF)-alpha, interleukin-1beta (IL-1beta), soluble IL-2 receptor (sIL-2R), IL-6, and chemokine IL-8 levels in patients with BD. We also determined the end product of lipid peroxidation (malondialdehyde (MDA)) in BD patients as an index for oxidative stress. METHODS: A total of 37 patients (19 men, 18 women) with BD (active, n = 17; inactive, n = 20) and 20 age-matched and sex-matched healthy control subjects (11 men, nine women) included in this cross-sectional, blinded study. Serum TNF-alpha, IL-1beta, sIL-2R, IL-6 and IL-8 levels were determined by a spectrophotometer technique using the immulite chemiluminescent immunometric assay. Lipid peroxidation was evaluated by Wasowicz et aL The levels of cytokines and lipid peroxidation in the active period were compared with the inactive period of the disease. Results are expressed as mean +/- standard error. RESULTS: IL-1beta levels were below the detection limits of the assay (< 5 pg/ml) in all samples. Mean levels of MDA (8.1+/-0.7 micromol/l), sIL-2R (800+/-38 U/ml), IL-6 (12.6+/-1.1 pg/ml), IL-8 (7.2+/-0.4 pg/ml), and TNF-alpha (7.9+/-0.5 pg/ml) in active BD patients were significantly higher than those in inactive patients (4.3+/-0.5 micromol/l, p < 0.01; 447+/-16 U/ml, p < 0.001; 8.3+/-0.6 pg/ml, p = 0.006; 5.3+/-0.1 pg/ml, p < 0.001; and 5.1 0.2 pg/ml, p < 0.001; respectively) or control subjects (2.1+/-0.2 micromol/l, p < 0.001; 446+/-20 U/ml, p < 0.001; 6.4+/-0.2 pg/ml, p < 0.001; 5.4+/-0.1 pg/ml, p < 0.001; and 4.7+/-0.1 pg/ml, p < 0.001, respectively). On the contrary, only the mean IL-6 level was significantly different between inactive BD and control subjects (p = 0.02). All acute phase reactants were significantly higher in active BD than in inactive period (for each, p < 0.01). Conclusions: High levels of sIL-2R, IL-6, IL-8 and TNF-alpha indicate the activation of immune system in BD. Serum sIL-2R, IL-6, IL-8 and TNF-alpha seem to be related to disease activity. Increased lipid peroxidation suggests oxidative stress in BD and therefore tissue damage in such patients. Amelioration of clinical manifestations would be envisaged by targeting these cytokines, chemokines and lipid peroxidation with pharmacological agents.     

Simultaneous measurement of multiple Th1 and Th2 serum cytokines in psoriasis and correlation with disease severity

BACKGROUND: Psoriatic plaques have been shown to contain increased levels of proinflammatory cytokines. Serum levels of interleukin (IL)-6, IL-7, IL-8, and interferon (IFN)-gamma have been reported elevated in psoriatic patients. AIM: To evaluate serum cytokine profiles in psoriasis patients by improved enzyme-linked immunosorbent assay (ELISA) technique and to correlate these levels with disease severity. METHODS: We analyzed single serum samples from 10 patients with active untreated psoriasis, two patients with active treated psoriasis, and five healthy volunteers for major T helper type 1 and T helper type 2 cytokines using the LINCOplex ELISA multi-analyte detection system that permits simultaneous detection of multiple cytokines from a single sample. The disease severity, including erythema, induration, scale, and surface area, was assessed. RESULTS: IFN-gamma was markedly elevated in all sera from psoriasis patients, 33.8 +/- 1.3 pg/ml (mean +/- standard error) versus 8 +/- 1.5 pg/ml for normal controls (p < 0.01), and positively correlated with all indices of disease severity (Spearman r > 0.6). IL-8 was also increased in psoriasis patients (24.4 +/- 1.8 pg/ml) versus normal controls (3.6 +/- 1.2 pg/ml) (p < 0.05) and positively correlated with the degree of erythema (Spearman r > 0.6). Mean IL-12 levels were decreased in sera from psoriasis patients (8.5 +/- 1.2 pg/ml) compared with normal controls (42.2 +/- 5.3 pg/ml) (p < 0.01). Also, serum IL-10 levels were below detection levels in psoriatics compared with controls (6.4 +/- 1.3 pg/ml). CONCLUSIONS: This new ELISA system allowed rapid and reliable detection of numerous cytokines in single serum samples from patients with psoriasis. We observed that IFN-gamma and IL-8 cytokines were elevated in psoriatics and correlated with parameters of disease severity while IL-10 and IL-12 were decreased.     

IFN-gamma is not induced through increased plasma concentrations of interleukin-12/interleukin-18 during human endotoxemia

Endotoxin administration to animals and humans is an accepted experimental model of Gram-negative sepsis, and endotoxin is believed to play a major role in triggering the activation of cytokines. In septic patients, the IL-12/IL-18/IFN-gamma axis is activated and correlates with mortality. Our aim was to investigate the effects of endotoxin administration in humans on the activation of the IL-12/IL-18/IFN-gamma axis. Seven healthy volunteers received E. coli endotoxin (O:113). Hemodynamics, temperature and the course of plasma concentrations of TNF-alpha, IL-1beta, IL-12, IL-18 and IFN-gamma were determined. Endotoxin administration resulted in the expected flu-like symptoms, a temperature of 38.8 +/- 0.3(o)C (p < 0.003), a decrease in mean arterial blood pressure of 14.8 +/- 1.8 mmHg (p < 0.0002) and an increase in heart rate of 27.5 +/- 4.8 bpm (p < 0.002) compared to baseline values. TNF-alpha increased from 16.6 +/- 8.2 to 927 +/- 187 pg/mL (p < 0.003). IL-1beta increased from 8.6 +/- 0.5 to 25.3 +/- 2.0 pg/mL (p < 0.0001). IL-12 showed no significant increase (8.2 +/- 0.2 to 9.3 +/- 0.8 pg/mL, p = 0.13), and all IL-18 measurements remained below the level of detection. In contrast, IFN-gamma showed an increase from 106.6 +/- 57.1 to 152.7 +/- 57.8 (p < 0.005). These results indicate that pathways other than the IL-12/IL-18 axis may induce IFN-gamma production in human endotoxemia.     

Regulation of interleukin-18 by THP-1 monocytoid cells stimulated with HIV-1 and Nef viral protein

Interleukin (IL)-18 is a proinflammatory cytokine that plays an important role in both innate and adaptive immune responses against several infectious pathogens. Relatively little is known about its production in HIV-1 infection, and there are controversial data on the influence of IL-18 on HIV-1 replication in vitro. In this study, we investigated the effect of HIV-1 infection, and challenge with recombinant HIV-1 proteins, on IL-18 production by THP-1 cells. This is a monocytoid cell line spontaneously producing IL-18, and consequently is particularly suitable for the study of HIV-1 effects on this type of cytokine regulation. The results reported here demonstrate a significant reduction in IL-18 secretion during HIV-infection. In fact, low levels of IL-18 were released until 120 h from viral challenge (15 +/- 11 pg/mL at 24 h and 17 +/- 13 at 96 h and < 12.5 at 120 h), whereas IL-18 production by uninfected control cells was 193 +/- 104 pg/mL and 214 +/- 114 pg/mL at 24 h and 120 h respectively. At 168 h of incubation, IL-18 production by infected and uninfected cells was found to be 164 +/- 88 pg/mL and 325 +/- 101 pg/mL respectively (p = 0.001). Of the following viral proteins: gp 120, p24 and Nef, only the last one induced decreased IL-18 secretion in the supernatants of THP-1 cells. This effect is more evident with the concentrations of 5 -1.25 microg/mL of Nef protein (p < 0.0001). In conclusion, our data show that HIV-1 and its regulatory protein, Nef, are able to down-regulate the release of IL-18, in vitro. These results confirm that a variety of modulating effects on the immune response, induced by HIV-infection, may facilitate progression of HIV-1 infection.     

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.     

Subcutaneous adipose tissue exerts proinflammatory cytokines after minimal trauma in humans

Inflammatory cytokines released from adipose tissue play an important role in different pathological processes. In the present study, we investigated the inflammatory cytokine response of human subcutaneous adipose tissue (SAT) by applying the open-flow microperfusion technique. Four standard 18-gauge microperfusion catheters were inserted into periumbilical SAT of eight healthy male volunteers [29 +/- 3 yr, BMI 24.3 +/- 1.9 (mean +/- SD)]. SAT probe effluents were collected at 60-min intervals for 8 h after catheter insertion. Different perfusion fluids were used to measure the local effect of insulin and/or glucose on the cytokine response. SAT probe effluents were analyzed for IL-1beta, IL-6, CXCL8 (IL-8), and TNF-alpha. SAT concentrations of IL-1beta increased 100-fold from 1.0 +/- 0.2 pg/ml (mean +/- SE) to 101.5 +/- 23.2 pg/ml (P < 0.001) after 8 h. A 130-fold increase was observed for CXCL8, from 49 +/- 29 to 6,554 +/- 1,713 pg/ml (P < 0.001). Furthermore, a 20-fold increase of IL-6 was observed within the first 5 h (from 159 +/- 123 to 3,554 +/- 394 pg/ml; P < 0.001), and a significant decline to 2,154 +/- 216 pg/ml (P < 0.01) was seen thereafter. Finally, TNF-alpha increased from 1.4 +/- 0.6 to 2.5 +/- 0.5 pg/ml (P < 0.05) in hour 2 and remained stable thereafter. Local administration of insulin exerted a stimulatory effect on the inflammatory response of IL-6. In conclusion, SAT exerts a highly reproducible and consistent proinflammatory cytokine response after minimally invasive trauma caused by the insertion of a catheter in humans.     

A novel IL-18BP ELISA shows elevated serum IL-18BP in sepsis and extensive decrease of free IL-18

IL-18 binding protein (IL-18BP) is a circulating antagonist of the proinflammatory Th1 cytokine IL-18. It effectively blocks IL-18 by forming a 1:1 high affinity (Kd=400 pM) complex, exhibiting a very low dissociation rate. We have developed a sandwich ELISA for IL-18BPa and determined its limit of detection (62 pg/ml). Interference by IL-18 and related cytokines, as well as cross reactivity with other IL-18BP isoforms (b, c, and d) were determined. Using this ELISA, we measured serum IL-18BPa in large cohorts of healthy individuals and in septic patients. Serum IL-18BPa in healthy individuals was 2.15+/-0.15 ng/ml (range 0.5-7 ng/ml). In sepsis, the level rose to 21.9+/-1.44 ng/ml (range 4-132 ng/ml). Total IL-18 was measured in the same sera by an electrochemiluminescence assay and free IL-18 was calculated based on the mass action law. Total IL-18 was low in healthy individuals (64+/-17 pg/ml) and most of it ( approximately 85%) was in its free form. Total IL-18 and IL-18BPa were both elevated in sepsis patients upon admission (1.5+/-0.4 ng/ml and 28.6+/-4.5 ng/ml, respectively). At these levels, most of the IL-18 is bound to IL-18BPa, however the remaining free IL-18 is still higher than in healthy individuals. We conclude that IL-18BPa considerably inhibits circulating IL-18 in sepsis. Yet, exogenous administration of IL-18BPa may further reduce circulating IL-18 activity.     

Studies on the allostimulatory function of dendritic cells from HCV-HIV-1 co-infected patients

There is increasing recognition of the potential morbidity and mortality associated with HIV- 1 and hepatitis C (HCV) co-infection. HIV appears to adversely affect HCV disease while the reciprocal effect of HCV on HIV remains controversial.We therefore studied the effect of co-infection on dendritic cell function versus HIV infection alone, as previous work has shown that HCV impairs dendritic cell (DC) function. HIV-1 positive individuals with HCV were matched for CD4 count, HIV-1 RNA viral load and therapy, to HIV-1 positive patients without HCV. Monocyte-derived DC were generated and mixed leukocyte reactions were performed. We assessed allostimulatory capacity with and without administration of exogenous Thl cytokines, using thymidine uptake and cell division analyses with the vital dye CFSE. We found that monocyte-derived DC from co-infected individuals showed no significant differences in allostimulatory capacity to ex vivo generated DC from HIV-1 infected individuals without HCV. Unlike the situation with HCV infection alone, this impairment was not reversed by increasing concentrations of either interleukin-2 or -12. Monocyte-derived DC from HIV- 1 and HCV co-infected individuals have a similar allostimulatory capacity to DC from matched patients with HIV-1 alone. These findings are compatible with results of prior clinical studies that found no evidence that HCV co-infection altered HIV disease progression and has implications for immunotherapeutic approaches in co-infected individuals.     

Plasma interleukin-18 is associated with viral load and disease progression in HIV-1-infected patients

Recent studies demonstrate persistent elevation of interleukin-18 (IL-18) concentration in human immunodeficiency virus type 1 (HIV-1)-infected patients. Due to pleiotropic action of IL-18 on the immune system, dysregulation of its synthesis may lead to inappropriate immune activation. The aim of this study was to determine possible correlation between IL-18 levels and the natural stages of HIV-1 infection. IL-18 plasma concentrations were determined in 42 patients in different stages of an HIV-1 infection and in 15 healthy controls. HIV infection resulted in a more than fourfold increase of plasma IL-18 concentration compared to healthy individuals (865 +/- 87 vs. 206 +/- 32 pg/ml, P < 0.001). Moreover, a positive correlation between plasma IL-18 concentration and HIV viral load was found (r = 0.44, P < 0.01). Further analysis showed marked elevation of IL-18 levels in late-stage symptomatic patients. Plasma IL-18 concentrations in patients receiving high-activity antiretroviral treatment (HAART) were significantly lower than in those not undergoing antiretroviral treatment. Individuals who did not reach viral suppression showed higher IL-18 plasma concentration than the group with achieved viral suppression. Excessive production of IL-18 observed in our study may promote viral replication and disease progression in advanced, especially late-stage HIV-infected patients. Furthermore, reduction of IL-18 concentration can be an important step in HAART-related immune restoration.