Cytokine regulation of ICAM-1 expression on human renal tubular epithelial cells in vitro.

Regulation of the intercellular adhesion molecule-1 (ICAM-1) expression on human renal tubular epithelial cells in culture (hKEC-1) was investigated. A large proportion of hKEC-1 cells from the primary cultures expressed the ICAM-1 antigen. Supernatants from mixed lymphocyte reaction (MLR) of both specific and third-party combinations augmented the expression of the ICAM-1 antigen, in a dose-dependent manner. A kinetic study revealed maximal augmentation by MLR supernatant on the first day, with a gradual decrease thereafter. Among several recombinant human cytokines tested, i.e., interferon-gamma, tumor necrosis factor-alpha, interleukin 1 alpha and beta, and IL-4, IFN-gamma, TNF-alpha, and IL-1 alpha/beta were shown to augment the expression of ICAM-1. MLR supernatants and IFN-gamma were more effective in augmenting ICAM expression than TNF-alpha and IL-1 alpha/beta. IFN-gamma upregulated ICAM-1 expression in a dose-dependent manner, and maximal augmentation was achieved on the first day. The MLR supernatants were shown to contain IFN-gamma and TNF-alpha, and the activity of the MLR supernatant was partially inhibited by neutralizing antibody against IFN-gamma. These data suggest that cytokines, especially IFN-gamma, TNF-alpha, and IL-1 alpha/beta, released by T cells and antigen-presenting cells upon recognition of alloantigens upregulate ICAM-1 expression on renal tubular epithelial cells. This may result in an increase in the attachment of graft-infiltrating T cells to the renal tubular cells, by the ICAM-1-LFA-1 interaction.     

Adhesion molecules in human islet beta-cells. De novo induction of ICAM-1 but not LFA-3.

Understanding how T lymphocytes recognize beta-cell autoantigens is essential for the elucidation of the pathogenesis of insulin-dependent diabetes mellitus. The increased and ectopic expression of HLA class I and II molecules detected in human beta-cells may facilitate this interaction. T-lymphocyte recognition of surface antigens also involves adhesion accessory molecules: intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 3 (LFA-3). These molecules not only allow cell contact but can also provide costimulatory signals for T-lymphocyte activation. Levels of ICAM-1 and LFA-3 expression in normal human islet cells and regulation of their expression by cytokines interferon-gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), and IL-6 have been studied by two-color immunofluorescence staining of pancreatic cryostat sections and fluorescence-activated cell sorter analysis. Neither ICAM-1 nor LFA-3 could be demonstrated in sections or in fresh cell preparations, but after 18 h of culture, beta-, alpha-, and delta-cells expressed spontaneously moderate levels of ICAM-1 (but not LFA-3). IFN-gamma and TNF-alpha alone or in combination strongly enhanced this spontaneous expression of ICAM-1 in a time- and/or dose-dependent and additive manner but had no effect on LFA-3. An SV40-transformed islet cell line showed high basal levels of both ICAM-1 and LFA-3, but the response to cytokines followed the same pattern as primary cultures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human renal epithelial cells express iNOS in response to cytokines but not bacteria

BACKGROUND: Epithelial cells form the mucosal barriers that prevent the entry of mucosal pathogens, and respond to bacterial infections by producing various host defense molecules. In this study, we examined the inducible nitric oxide synthase (iNOS) response of primary human renal tubular epithelial cells (HRTEC) following infection with uropathogenic Escherichia coli Hu734, or stimulation with lipopolysaccharide (LPS) or cytokines. METHODS: Induction of iNOS was examined by RT-PCR, Western blot, immunohistochemistry and nitrite measurements. The effects of endogenously produced nitric oxide (NO), and exogenously applied DETA/NO, SIN-1 and H2O2 on cell viability were analyzed using a respiration assay. RESULTS: HRTEC did not produce NO following infection with E. coli Hu734, LPS alone, or in combination with interferon-gamma (IFN-gamma), even though these agents caused a marked increase in iNOS expression by RAW 264.7, a macrophage cell line. In contrast, iNOS protein and mRNA expression by HRTEC increased after exposure to a cytokine mixture consisting of interleukin (IL)-1beta, tumor necrosis factor-alpha (TNF-alpha) and IFN-gamma. This was due to the combination of IL-1beta and IFN-gamma, but the individual cytokines had no effect. Inducible NOS-expressing cell cultures showed reduced viability, and this effect was inhibited with the NOS inhibitor L-NMMA in RAW 264.7 cells, but not in HRTEC. HRTEC were more sensitive to oxidative stress induced by H2O2 than to nitrogen stress induced by DETA/NO. CONCLUSIONS: We conclude that uropathogenic E. coli that attach to HRTEC fail to directly activate iNOS expression, and that iNOS expression during bacterial infection is more likely to result from stimulation by local cytokines such as IL-1beta and IFN-gamma.     

Intestinal graft versus native liver cytokine expression in a rat model of intestinal transplantation: effect of donor-specific cell augmentation

INTRODUCTION: Immunomodulation by portal vein delivery of donor antigen reduces intestinal graft rejection. We investigated the impact of portal venous donor-specific cell augmentation (blood versus bone marrow) on cytokine expression in intestinal grafts versus native livers. METHODS: Ten groups of intestinal transplants (brown Norway male to Lewis female rats) varied by (1). the type of donor-specific cell augmentation and (2). the use and dose of tacrolimus-based immunosuppression. Tissue samples for histologic analysis and cytokine mRNA analysis were obtained at designated time points. RESULTS: Without immunosuppression, no type of cell augmentation reduced the rate of rejection. With immunosuppression, outcome was significantly better after portal donor-specific blood transfusion (versus bone marrow infusion). Irrespective of the type of cell augmentation, severe rejection caused strong intragraft expression of IL-1alpha, IL-1beta, IFN-gamma, and TNF-alpha; liver expression mainly involved TNF-alpha. Of note, nonimmunosuppressed, cell-augmented rats showed hardly any differences in cytokine expression in their grafts versus significant increases in their native livers. With immunosuppression, bone marrow infusion (versus blood transfusion) increased intragraft cytokine expression of IL-1alpha, IL-1beta, IFN-gamma, as well as TNF-alpha, and liver expression of IL-1beta. CONCLUSIONS: (1). Rejection and donor-specific cell augmentation independently caused differences in intragraft versus native liver cytokine expression after intestinal transplants. (2). Portal donor-specific blood transfusion (versus bone marrow infusion) lowered the incidence of rejection and diminished intragraft cytokine up-regulation. (3). In our study, TNF-alpha appeared to be the cytokine most strongly associated with rejection.     

Intestinal graft versus native liver cytokine expression in a rat model of intestinal transplantation with and without donor-specific cell augmentation

BACKGROUND: Immunomodulatory strategies such as donor-specific bone marrow or blood transfusions have been used to promote engraftment after intestinal transplants. We previously showed that delivery of donor antigen via the portal vein can effectively reduce the rate of intestinal graft rejection. The purpose of our current study was to investigate the impact of donor-specific cell augmentation (blood versus bone marrow) via the portal vein on cytokine expression in intestinal grafts versus native livers. MATERIAL AND METHODS: We performed heterotopic small intestinal transplants between male Brown-Norway (donor) and female Lewis (recipient) rats. We studied 10 groups according to the type of donor-specific cell augmentation and the use and dose of immunosuppressive therapy. For cell augmentation, donor-specific blood or bone marrow was transfused via the donor portal vein immediately before graft implantation. For immunosuppression, tacrolimus was used post-transplant at a high or low dose. Control rats received neither immunosuppression nor cell augmentation. Tissue samples for histological assessment were obtained at designated time points. RNA was extracted from intestinal graft and native liver biopsies for cytokine measurements (IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IFN-gamma, TNF-alpha, and TNF-beta). Chimerism levels were determined using Q-PCR analysis. RESULTS: Without concurrent immunosuppression, neither portal donor-specific blood nor bone marrow transfusion reduced the rate of rejection. With immunosuppression, outcome was significantly better after portal donor-specific blood (versus bone marrow) transfusion. Irrespective of the type of donor-specific cell augmentation, severe rejection caused strong cytokine expression in the grafts of IL-1 alpha, IL-1 beta, IFN-gamma, and TNF-alpha; in the native livers, mainly of TNF-alpha (with IFN-gamma showing hardly any increase). In general, rejection caused stronger cytokine expression in the grafts than in the native livers. Mild rejection correlated well with strong intragraft expression of IL-6, TNF-alpha, and TNF-beta (early rejection markers); severe rejection with IL-1 alpha, IL-1 beta, IFN-gamma, and TNF-alpha (late rejection markers).In addition to cell augmentation per se, the type of cell augmentation also had an impact on cytokine expression in both grafts and native livers. Cell-augmented (versus tacrolimus-treated) rats showed hardly any differences in intragraft cytokine expression, but the expression of almost all cytokines was significantly stronger in the native livers. With immunosuppression, bone marrow infusion increased intragraft cytokine expression of IL-1 alpha, IL-1 beta, IFN-gamma, and TNF alpha, as well as liver cytokine expression of IL-1 beta, compared to blood transfusion. This finding reflected the more advanced rejection stages in the bone marrow infused group; different types of donor-specific cell augmentation had similar effects on liver cytokine expression. In the absence of myoablative therapy, chimerism levels were low, in both cell-augmented and non-cell-augmented groups. CONCLUSIONS: Rejection and donor-specific cell augmentation independently causes differences in intragraft versus native liver cytokine expression after intestinal transplants. Portal donor-specific blood transfusion, as compared with donor-specific bone marrow infusion, lowered the incidence of rejection and diminished intragraft cytokine up-regulation.     

Fetal pig beta cells are resistant to the toxic effects of human cytokines

BACKGROUND: The cytokine tumour necrosis factor-alpha (TNF-alpha) is thought to be responsible for primary nonfunction of islets when transplanted. This, and two other cytokines, interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) are also implicated in the autoimmune destruction of beta cells. It is unknown if the fetal pig beta cell, which is being transplanted as a treatment for type 1 diabetes, is affected by these cytokines. METHODS: We compared the effects of the cytokines on the function and viability of adult and fetal pig beta cells. The cells were cultured for up to 3 days in the presence of 2000 pg/ml of human IL-1beta, 1000 U/ml of TNF-alpha, and 1000 U/ml of IFN-gamma, as well as 1000 U/ml of porcine IFN-gamma. Cumulative insulin levels, insulin content, metabolic activity, and viability of these cells were examined. Additionally, nitric oxide production and the activity of antioxidant enzymes in these cells were also determined. RESULTS: TNF-alpha and the combination of the three human cytokines caused a transient increase in cumulative insulin levels. TNF-alpha alone enhanced insulin content on day 3. There was no effect of these human cytokines on mitochondrial function and viability. In contrast, porcine IFN-gamma inhibited fetal pig beta cell function and also caused their death. Adult pig islets are sensitive to the toxic effects of human TNF-alpha, IL-1beta, the combination of the three cytokines, and porcine IFN-gamma. The activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase were significantly higher in fetal pig beta cells than in adult islets, implying that this may be the reason for the lack of adverse effects of the cytokines on the fetal beta cell. CONCLUSION: Fetal pig beta cells are resistant to the toxic effect of the human cytokines, TNF-alpha and IL-1beta, in vitro. This resistance suggests that fetal, but not adult beta cells, when transplanted into humans with type 1 diabetes may be protected from primary nonfunction and will be partially protected from autoimmune destruction.     

Cloning of porcine intercellular adhesion molecule-1 and characterization of its induction on endothelial cells by cytokines

BACKGROUND: The transplantation of pig organs into humans requires a detailed knowledge of similarities and differences between the two species in the molecular physiology of host defense mechanisms. We therefore set out to identify porcine intercellular adhesion molecule (ICAM)-1 and to characterize its expression by endothelial cells. METHODS: Porcine ICAM-1 cDNA was isolated from an endothelial cell cDNA library. An anti-pig ICAM-1 monoclonal antibody was generated and used to investigate the regulation by cytokines of ICAM-1 expression by porcine aortic endothelial cells (PAEC), using flow cytometry. RESULTS: We found that porcine ICAM-1 was similar in primary structure to human ICAM-1, with five Ig-like domains. COS-7 cells transfected with porcine ICAM-1 supported beta2 but not alpha4 integrin-dependent adhesion of human T lymphoblasts. There was a low-level surface expression of ICAM-1 on unstimulated PAEC and increased expression after stimulation with tumor necrosis factor (TNF)-alpha. However expression of ICAM-1 seemed to be significantly lower than that of vascular cell adhesion molecule-1, both on unstimulated and TNF-alpha-activated PAEC. Recombinant porcine interferon-gamma weakly stimulated ICAM-1 expression when incubated alone with PAEC but had an inhibitory effect on the increase in ICAM-1 due to TNF-alpha, both at 8 and 24 hr. CONCLUSIONS: Our observations confirm the existence of ICAM-1 in the pig and provide novel insights into how porcine and human endothelial cells differ in terms of adhesion molecule expression and cytokine responsiveness. Such differences are potentially important in interpreting models of inflammation in the pig and also in understanding the process of rejection of porcine xenografts.     

Regulation of inducible class II MHC,costimulatory molecules,and cytokine expression in TGF-beta1 knockout renal epithelial cells: effect of exogenous TGF-beta1

As reports of mice genetically deficient for TGF-beta1 demonstrated aberrant renal class II MHC expression, we investigated inducible class II MHC expression on renal tubular epithelial cells derived from TGF-beta1 knockout (-/-) and wild-type (+/+) mice. IFN-gamma markedly upregulated class II MHC (I-A(b)) expression in both (-/-) and (+/+) tubular epithelial cells. Coincubation studies of (+/+) and (-/-) tubular epithelial cells with IFN-gamma+LPS, or pretreatment of these cells with TGF-beta1, revealed inhibition of IFN-gamma-induced I-A(b) mRNA and cell surface expression that occurred via a decrease in class II transactivator gene expression in both (+/+) and (-/-) tubular epithelial cells. In addition, ICAM-1 was constitutively expressed on both (+/+) and (-/-) tubular epithelial cells and was upregulated by IFN-gamma or IFN-gamma+LPS. ICAM-1 expression in (+/+) and (-/-) tubular epithelial cells, however, was decreased by TGF-beta1. Parallel analysis evaluating B7-1 expression detected low levels of B7-1 in unstimulated (+/+) and (-/-) tubular epithelial cells that were increased by IFN-gamma, LPS, and IFN-gamma+LPS. IFN-gamma+LPS-mediated upregulation of B7-1 was also blocked by pretreatment with TGF-beta1. Cytokine analysis detected significantly higher levels of TNF-alpha and MIP-1alpha mRNA in all treated (-/-) preparations than in (+/+) tubular epithelial cell controls. These studies demonstrate normal patterns of class II MHC, ICAM-1, and B7 expression in TGF-beta1 (-/-) tubular epithelial cells in response to IFN-gamma, LPS, and TGF-beta1. Upregulated cytokine expression at baseline and in response to proinflammatory mediators is apparent in (-/-) tubular epithelial cells, however, and suggests that dysregulation of cytokine expression in inflammatory responses may be a primary event in multifocal inflammation observed in TGF-beta1-deficient animals.     

The effect of anaesthesia and surgery on plasma cytokine production

The aim of this study was to investigate cytokine production in response to anaesthesia [total intravenous anaesthesia (TIVA) with propofol, sufentanil and atracurium] and surgery (laparoscopic vs. open cholecystectomy). Forty adult patients, ASA I-II, undergoing elective laparoscopic (group 1) or open (group 2) cholecystectomy were studied. Venous blood samples for measurement of interleukin (IL)-1beta, IL-2, IL-4, IL-6, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were taken before the induction of anaesthesia, pre-incisionaly, at the end of anaesthesia and surgery and 24-h postoperatively. Pre-incisionaly, in both groups, IL-1beta, IL-4, IL-6, TNF-alpha and IFN-gamma did not show a significant change, whereas IL-2 showed a significant decrease (p < 0.005 in group 1 and p < 0.001 in group 2) compared with pre-induction levels. By the end of anaesthesia and surgery, IL-1beta, IL-2, IL-4, IL-6 and TNF-alpha showed a significant increase in group 2 (p < 0.005 for IL-1beta, IL-2 and IL-4, and p < 0.05 for IL-6 and TNF-alpha); while in group 1, only IL-2 showed a significant increase (p < 0.01) and IFN-gamma showed a significant decrease (p < 0.05) compared with pre-incisional levels. By 24-h postoperatively, IL-1beta, IL-4, IL-6 and TNF-alpha had decreased significantly in group 2 (p < 0.005 for IL-4 and p < 0.05 for the others); whereas in group 1, IL-2 and IFN-gamma showed a significant increase (p < 0.005) compared with the end of anaesthesia and surgery level. In conclusion, TIVA with propofol, sufentanil and atracurium does not seem to have a significant effect on IL-1beta, IL-4, IL-6, TNF-alpha and IFN-gamma release. IL-2 was the only cytokine to show a significant decrease due to the effect of anaesthesia alone in both groups. The cytokine response to open cholecystectomy stimulated both the pro-inflammatory (IL-1beta, IL-6 and TNF-alpha) and the anti-inflammatory (IL-4) components, while this response was absent in laparoscopic cholecystectomy.     

Critical involvement of stress-activated mitogen-activated protein kinases in the regulation of intracellular adhesion molecule-1 in serosal fibroblasts isolated from patients with Crohn's disease

BACKGROUND: Stricture formation in Crohn's disease occurs as a result of persistent fibroblast activation. Chronic inflammation seen in patients with Crohn's disease leads to enhanced adhesion molecule expression in fibroblasts. Stress-activated mitogen-activated protein kinases are critical signaling pathways that control expression of intracellular adhesion molecule-1 (ICAM-1) in inflammation. The purpose of this study was to investigate the involvement of stress-activated mitogen-activated protein kinases in the regulation of ICAM-1 expression by tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in serosal fibroblasts isolated from patients with Crohn's disease. STUDY DESIGN: Fibroblasts were isolated from serosal biopsies of strictures in patients with Crohn's disease and normal colon in patients with colorectal carcinoma. Cell surface and whole cell ICAM-1 expression were evaluated by flow cytometry and Western blot analysis, respectively. Cells were stimulated with TNF-alpha and IL-1beta. To determine the mitogen-activated protein kinase signaling pathway required for ICAM-1 induction, cells were pretreated with inhibitors to Jun N-terminal kinase, p38 kinase, and p42/44 kinase. RESULTS: Baseline ICAM-1 expression was higher (p < 0.001) in fibroblasts isolated from strictures in patients with Crohn's disease (3.2 +/- 0.3) as compared with nonstrictured Crohn's fibroblasts (2.1 +/- 0.3) and control fibroblasts (1.6 +/- 0.1). TNF-alpha and IL-1beta increased ICAM-1 expression in both control and Crohn's disease. Pretreatment of fibroblasts with the Jun N-terminal kinase inhibitor dimethylaminopurine abolished TNF-alpha- and IL-1beta-stimulated ICAM-1 expression. CONCLUSIONS: Serosal fibroblasts isolated from strictures of patients with Crohn's disease demonstrate enhanced expression of ICAM-1. TNF-alpha and IL-1beta upregulate ICAM-1 expression in serosal fibroblasts through a Jun N-terminal kinase signaling pathway. Specific inhibition of inflammatory signaling pathways could provide novel therapeutic targets for treatment of Crohn's disease.     

Generation of complement C3 and expression of cell membrane complement inhibitory proteins by human bronchial epithelium cell line

BACKGROUND: The interrelationship between human airway epithelium and complement proteins may affect airway defence, airway function, and airway epithelial integrity. A study was undertaken to determine (1) whether unstimulated human bronchial epithelium generates complement proteins and expresses cell membrane complement inhibitory proteins (CIP) and (2) whether stimulation by proinflammatory cytokines affects the generation of complement and expression of cell membrane CIP by these cells. METHODS: Human bronchial epithelium cell line BEAS-2B was cultured in a serum-free medium. Cells were incubated with and without proinflammatory cytokines to assess unstimulated and stimulated generation of complement C3, C1q and C5 (by ELISA), and to examine the expression of cell membrane CIP decay accelerating factor (DAF; CD55), membrane cofactor protein (MCP; CD46), and CD59 (protectin) by flow cytometry analysis. RESULTS: Unstimulated human bronchial epithelial cell line BEAS-2B in serum-free medium generates complement C3 (mean 32 ng/10(6) cells/72 h, range 18-52) but not C1q and C5, and expresses cell membrane DAF, MCP, and CD59. Interleukin (IL)-1alpha (100 U/ml/72 h) and tumour necrosis factor (TNF-alpha; 1000 U/ml/72 h) increased generation of C3 up to a mean of 78% and 138%, respectively, above C3 generation by unstimulated cells. DAF was the only cell membrane CIP affected by cytokine stimulation. Interferon (IFN)-gamma (10 U/ml/72 h) and TNF-alpha (1000 U/ml/72 h) increased DAF expression up to a mean of 116% and 45%, respectively, above that in unstimulated cells. MCP and CD59 expression was not consistently affected by IL-1alpha, TNF-alpha, or IFN-gamma. CONCLUSIONS: Local generation of complement C3 and expression of cell membrane CIP by human bronchial epithelium and its modulation by proinflammatory cytokines might be an additional regulatory mechanism of local airway defence and may affect airway function and epithelial integrity in health and disease.     

Cytokine pattern in aneurysmal and occlusive disease of the aorta.

BACKGROUND: Prominent inflammatory infiltrates of macrophages and T-lymphocytes are found in both aortic occlusive disease (AOD) and abdominal aortic aneurysms (AAA). These cells secrete different cytokines that might affect matrix turnover through modulation of matrix metalloproteinase expression. A different cytokine pattern might account for the evolution of AOD vs AAA. MATERIALS AND METHODS: Six different cytokines were examined to determine whether AOD and AAA could be characterized by unique cytokine patterns. AOD (n = 8) and AAA (n = 8) tissues were collected and serially treated with salt, dimethyl sulfoxide, and urea buffers to extract the soluble matrix or cell-bound cytokines. Levels of IL-1 beta, TNF-alpha, IL-10, IL-12, and IFN-gamma were measured by immunoenzymatic methods. Additionally, RNA levels of IL-12 and IFN-gamma were measured. RESULTS: AAA tissue contained higher levels of IL-10 compared to AOD tissue (P < 0.05). Higher levels of the proinflammatory cytokines IL-1 beta, TNF-alpha, and IL-6 were found in AOD (P < 0.05). mRNA levels of IL-12 and IFN-gamma did not differ between the diseases. Aortic tissues contained large amounts of matrix or cell-bound cytokines. CONCLUSIONS: AAA is characterized by greater levels of IL-10 while IL-1 beta, TNF-alpha, and IL-6 are higher in AOD. Targeted deletion of these cytokines in animal models might help in identifying their role in the progression of AAA.     

Effect of histamine on intercellular adhesion molecule-1 expression and production of interferon-gamma and interleukin-12 in mixed lymphocyte reaction stimulated with interleukin-18

BACKGROUND: Interleukin (IL)-18 was identified as an interferon (IFN)-gamma-inducing factor and was demonstrated to up-regulate the expression of intercellular adhesion molecule (ICAM)-1 on human monocytes. In organ transplantation, elevation of plasma IL-18 levels has been reported during acute rejection. In the present study, we examined the effect of IL-18 on human mixed lymphocyte reaction (MLR), an in vitro model of acute rejection after organ transplantation. We also investigated the modulatory effects of histamine on IL-18 action because histamine has been demonstrated to be a modulator of IL-18 effect and a mediator of inflammation. METHODS: We measured the expression of ICAM-1 on human monocytes in MLR in the presence or absence of IL-18 by flow cytometer and determined the associated production of IFN-gamma and IL-12 by ELISA. The modulatory effects of histamine and the relevant histamine receptor subtypes were characterized pharmacologically. RESULTS: The expression of ICAM-1 on monocytes in MLR was markedly enhanced by the addition of IL-18 in a concentration- and time-dependent manner. In parallel to ICAM-1 up-regulation, IL-18 significantly enhanced the production of IFN-gamma and IL-12 in MLR. Histamine concentration-dependently inhibited ICAM-1 expression and cytokine production in MLR stimulated with IL-18, whereas histamine alone did not show any effects on these responses in the absence of IL-18. The effects of histamine on both ICAM-1 expression and cytokine production were mimicked by the selective H2-receptor agonists 4-methylhistamine and dimaprit and were antagonized by the H2-receptor antagonist famotidine but not by H1- and H3-receptor antagonists. CONCLUSION: IL-18 strongly enhanced human MLR with respect to ICAM-1 expression and cytokine production. The fact that histamine could inhibit the IL-18-stimulated MLR implies that immunomodulation by histamine and selective H2-receptor agonists may have an important role in future immunosuppressive strategies.     

Variations in IB1/JIP1 expression regulate susceptibility of beta-cells to cytokine-induced apoptosis irrespective of C-Jun NH2-terminal kinase signaling

We previously reported that interleukin-1beta (IL-1beta) alone does not cause apoptosis of beta-cells, whereas when combined with gamma-interferon (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), it exerts a distinct apoptotic effect. Studies in beta-cell lines indicated that IL-1beta reduced expression of islet brain (IB)-1/JNK interacting protein (JIP)-1, a JNK scaffold protein with antiapoptotic action. We examined whether variations in IB1/JIP-1 expression in purified primary beta-cells affect their susceptibility to cytokine-induced apoptosis. Exposure to IL-1beta for 24 h decreased cellular IB1/JIP-1 content by 66 +/- 17%; this IL-1beta effect was maintained in the presence of TNF-alpha + IFN-gamma, which did not influence IB1/JIP-1 levels by themselves. Addition of IL-1beta to TNF-alpha + IFN-gamma increased apoptosis from 20 +/- 2% to 59 +/- 5%. A similar increase in TNF-alpha + IFN-gamma-induced apoptosis was produced by adenoviral expression of antisense IB1/JIP-1 and was not further enhanced by addition of IL-1beta, indicating that IL-1beta-mediated suppression of IB1/JIP-1 in beta-cells increases their susceptibility to cytokine-induced apoptosis. However, adenovirally mediated overexpression of IB1/JIP-1 also potentiated TNF-alpha + IFN-gamma-induced apoptosis, suggesting that the antiapoptotic effect of IB1/JIP-1 depends on well-defined cellular levels. We conclude that the IB1/JIP-1 level in beta-cells can control their susceptibility to apoptosis independent of JNK signaling.     

Agonist of peroxisome proliferator-activated receptor-gamma, rosiglitazone, reduces renal injury and dysfunction in a murine sepsis model.

BACKGROUND: Agonists of the peroxisome proliferator-activated receptor-gamma may help to regulate inflammation by modulating the production of inflammatory mediators and adhesion molecules. The purpose of this study was to determine the protective effects of rosiglitazone on renal injury in a sepsis model and to explore the mechanism. METHODS: In lipopolysaccharide (LPS)-induced mouse sepsis, we examined the effect of rosiglitazone on LPS-induced overproduction of inflammatory mediators, on the expression of adhesion molecules in renal tubular epithelial cells and on renal function. The mechanism of the protective effect was investigated in vitro using human renal tubular epithelial cells. RESULTS: Rosiglitazone significantly decreased serum tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta levels during sepsis. The levels of blood urea nitrogen and creatinine were significantly lower in mice pre-treated with rosiglitazone than that in LPS-treated mice. Rosiglitazone reduced the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in tubular epithelial cells and interstitium of LPS-treated mice. Pre-treatment with rosiglitazone reduced the infiltration of macrophages/monocytes in renal tissue. In cultured tubular epithelial cells, rosiglitazone significantly decreased the expression of ICAM-1 and VCAM-1 induced by TNF-alpha or IL-1beta, inhibited the degradation of inhibitor kappaBalpha (IkappaBalpha) and blocked the activation of the p65 subunit of nuclear factor (NF)-kappaB. CONCLUSIONS: These results indicate that pre-treatment with rosiglitazone attenuated the production of TNF-alpha and IL-1beta and reduced adhesion molecule expression in renal tubular epithelial cells of LPS-treated mice. Rosiglitazone has an anti-inflammatory effect in renal tubular epithelial cells through the inhibition of NF-kappaB activation.     

Intracellular monocyte cytokine production and CD 14 expression are up-regulated in severe vs mild chronic heart failure.

BACKGROUND: The role of circulating monocytes in the process of low-grade inflammation, characteristic of chronic heart failure (CHF), has recently been questioned. Lipopolysaccharide (LPS) desensitization has been proposed to mediate reduced monocyte cytokine elaboration in patients with severe CHF. METHODS: Intracellular monocyte production of interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha, and monocyte CD 14 expression were measured flow-cytometrically without and after 8-hour LPS stimulation in 46 patients with CHF and in a healthy control group. RESULTS: Basal cytokine concentrations were similar for the control and the mild CHF groups (New York Heart Association [NYHA] Class I or II). After LPS stimulation, IL-6 (p=0.002) and TNF-alpha levels (p=0.001) were lower in the latter group, whereas IL-1 beta production was comparable. For the moderate-severe CHF patients, unstimulated IL-1 beta (p=0.04) was higher, whereas IL-6 (p=0.2) and TNF-alpha (p=0.1) levels were not different from the controls. Measurement of LPS-stimulated cytokine production showed no differences between the control group and patients with moderate-severe CHF (all p= 0.5). Upon comparing mild vs moderate-severe CHF patients, higher levels of unstimulated cytokine production (IL-1 beta, p=0.002; IL-6, p=0.01; TNF-alpha, p=0.003), stimulated IL-1 beta (p=0.002) and IL-6 (p=0.008) were found in the latter patients. CD 14 expression in the moderate-severe CHF group was higher than in the mild-CHF group (p = 0.03) and was strongly related to stimulated IL-1 beta (r=0.62, p<0.0001), IL-6 (r=0.56, p=0.0002) and TNF-alpha (r=0.41, p=0.006) production. CONCLUSIONS: CD 14 expression and monocyte cytokine production, both unstimulated and after LPS stimulation, are increased in moderate-severe CHF when compared with mild CHF. These data suggest that circulating monocytes, possibly via increased CD 14 expression, may play a significant role in the immunologic dysbalance observed in advanced CHF.     

Effects of mycophenolic acid on IL-6 expression of human renal proximal and distal tubular cells in vitro.

BACKGROUND: Interleukin-6 (IL-6) is a multifunctional cytokine which regulates immune responses and host defence mechanisms. IL-6 has been found to be increased in certain inflammatory conditions of the kidney, in which tubular epithelial cells play a pivotal role. Human renal tubular cells express IL-6. Until now no data about the effect of the immunosuppressant drug mycophenolic acid (MPA) on IL-6 expression were available. METHODS: Proximal and distal tubular epithelial cells (PTC/DTC) have been isolated immunomagnetically. Confluent monolayers were stimulated with interleukin-1beta (IL-1beta; 25 U/ml), IL-1beta+ MPA (0.25-50 micro M) or MPA alone for 48 h. Release of IL-6 protein into the supernatant was evaluated with an enzyme immunoassay, IL-6 mRNA expression was evaluated using the Quantikine mRNA kit. RESULTS: After IL-1beta stimulation, a highly significant 2.6- (PTC) and 3.8-fold (DTC) upregulation of IL-6 expression was detectable. IL-6 mRNA was upregulated by IL-1beta [1.57- (PTC) and 2.03-fold (DTC)]. MPA inhibited this cytokine-induced IL-6 expression in a dose-dependent manner. Incubation with the lowest MPA concentration had no effect on the stimulated upregulation, whereas all higher doses significantly decreased IL-6 expression. Dexamethasone significantly inhibited the cytokine-induced IL-6 protein release in PTC, but not in DTC. CONCLUSIONS: In this study we demonstrated for the first time an inhibitory effect of MPA on the stimulated IL-6 expression of renal tubular epithelial cells. In contrast to older data, which showed a synergistic upregulation of the expression of a CC-chemokine by a combination of cytokines and MPA, in the present study we could demonstrate an immunosuppressive effect of MPA on the expression of an important cytokine.