Effect of beta2-adrenergic receptor agonists on intercellular adhesion molecule (ICAM)-1, B7, and CD40 expression in mixed lymphocyte reaction

BACKGROUND

The plasma interleukin (IL)-18 level is elevated in acute rejection after organ transplantation. Although beta2-adrenergic receptor (AR) agonists suppress the rejection of organ and tissue transplants, little is known about their action mechanisms. We examined the effects of endogenous catecholamines and beta2-AR agonists on the expression of intercellular adhesion molecule (ICAM)-1, B7.1, B7.2, CD40, and CD40 ligand (CD40L) in human mixed lymphocyte reaction (MLR) and in an in vitro model of acute rejection in the presence or absence of IL-18.

METHODS

ICAM-1, B7.1 B7.2, CD40, and CD40L expression on monocytes was measured by flow cytometry, and the production of interferon (IFN)-gamma and IL-12 was determined by enzyme-linked immunosorbent assay. Lymphocytes proliferation in MLR was measured by [3H]-thymidine uptake. The relevant AR subtypes were characterized using subtype-selective agonists and antagonists.

RESULTS

beta2-AR agonists inhibited the expression of ICAM-1 and CD40 during MLR in the absence of IL-18. Among IL-18-induced expression of ICAM-1, B7.1, B7.2, CD40, and CD40L, beta2-AR agonists inhibited ICAM-1 and CD40 expression. beta2-AR agonists prevented the production of IFN-gamma and IL-12 in the presence of IL-18 but had no effect in the absence of IL-18. beta2-AR agonists inhibited lymphocyte proliferation in IL-18-treated MLR.

CONCLUSIONS

We found that beta2-AR agonists strongly inhibited the expression of ICAM-1 and CD40, irrespective of the presence or absence of IL-18, which is different from that of histamine and prostaglandin E2.

[Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2002 and March 2003]

Tendency of isolated bacteria from infections in general surgery during the period from April 2002 to March 2003 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 334 strains were isolated from 131 (75.3%) of 174 patients with surgical infections. One hundred and seventy-one strains were isolated from primary infections, and 163 strains were isolated from post-operative infections. From primary infections, anaerobic Gram-positive bacteria were predominant, while aerobic Gram-positive bacteria were predominant from postoperative infections. Among aerobic Gram-positive bacteria, although the isolation rate of Staphylococcus aureus was the highest, followed by that of Enterococcus faecalis from primary infections, the isolation rate of E. faecalis was the highest from postoperative infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae and Pseudomonas aeruginosa in this order, and from postoperative infections, E. coli was the most predominantly isolated, followed by P. aeruginosa, Enterobacter cloacae, and Citobacter freundii. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both types of infections. The isolation rate of aerobic Gram-negative bacteria from primary infections and that of aerobic Gram-positive bacteria from postoperative infections were high in the last several years. We noticed no vancomycin-resistant Gram-positive cocci nor P. aeruginosa producing metallo-beta-lactamase. But we noticed cefazolin-resistant E. coli probably producing extended spectrum beta-lactamase.

Histamine downregulates CD14 expression via H2 receptors on human monocytes

Lipopolysaccharide (LPS) binds to LPS-binding protein (LBP) in plasma and is delivered to the cell surface receptor CD14 on human monocyte. LPS is transferred to the transmembrane signaling receptor toll-like receptor (TLR) 4. In the present study, the effect of histamine on the expression of CD14 on human monocytes was investigated. Histamine concentration- and time-dependently decreased the expression of cell surface CD14, whereas histamine did not decrease mRNA for CD14 nor increase soluble CD14 (sCD14). The inhibitory effects of histamine on CD14 expression were antagonized by H2-receptor antagonist, but not by H1 and H3/H4 antagonist. The effects of selective H2-receptor agonists, 4-methylhistamine and dimaprit, on CD14 expression mimicked that of histamine indicating that histamine regulated CD14 expression through the stimulation of H2-receptors. The pretreatment with histamine partially inhibited the LPS-induced TNF-alpha production in human peripheral blood mononuclear cells (PBMC). Such inhibition might be due to the down-regulation of CD14 expression on monocytes by histamine.

MAP kinase-mediated proliferation of DLD-1 carcinoma by the stimulation of protease-activated receptor 2

Protease-activated receptor-2 (PAR-2) has been demonstrated to be highly expressed in the gastrointestinal tract. In the present study, we investigated the effects of PAR-2 stimulation on the cell signaling and proliferation of DLD-1, a human colon carcinoma cell line, in comparison with the PAR-1 stimulation. PAR-2 stimulation by agonist peptide SLIGKV concentration-dependently induced the increase in [Ca2+]i and the proliferation of DLD-1 whereas the inverse peptide LSIGKV did not. Trypin (10(-9) M), an agonist protease for PAR-2, also enhanced the proliferation of DLD-1. The proliferative response of DLD-1 to PAR-2 stimulation was associated with the transient phosphorylation of MEK and MAP kinase, but not p38 MAP kinase and JNK. Inhibition of MEK by PD98059 (50 microM) completely inhibited the proliferation-stimulating effects as well as the phosphorylation of MAP kinase induced by PAR-2 agonist peptide (100 microM) and trypsin (10(-9) M). The prolonged treatment with PAR-2 agonist peptide for more than one hour was required for the enhanced proliferative response, suggesting the existence of unknown long-lasting cooperative signaling with MAP kinase cascade. PAR-1 stimulation by the agonist peptide SFLLRN (100 microM) or thrombin (10(-8) M) produced Ca2+ signaling, however, the stimulation neither produced the cell proliferative response nor the activation of MEK-MAP kinase cascade. These results indicated that Ca2+ signaling induced by PARs activation was not enough for inducing the cell proliferation in DLD-1 cells and that stimulation of PAR-2 can induce the activation of MEK-MAP kinase cascade, leading to the growth promoting response.

Unique regulation profile of prostaglandin e1 on adhesion molecule expression and cytokine production in human peripheral blood mononuclear cells

In the present study, we examined the effects of prostaglandin E1 (PGE1) on the expression of intercellular adhesion molecule (ICAM)-1, B7.1, B7.2, CD40, and CD40 ligand (CD40L) on peripheral blood mononuclear cells (PBMC) using fluorescence-activated cell sorting analysis as well as its effects on cytokine production using enzyme-linked immunosorbent assay. Whereas no inhibitor of spontaneous expression of adhesion molecules was reported, we found that PGE1 inhibited spontaneous ICAM-1, B7.2, and CD40 expression on monocytes in a concentration-dependent manner but had no effect on the expression of B7.1 and CD40L. Although interleukin (IL)-18 induced the expression of ICAM-1, B7.2, CD40, and CD40L, PGE1 prevented IL-18-induced expression of ICAM-1, B7.2, and CD40. We examined the involvement of five subtypes of PGE1 receptors (IP, EP1, EP2, EP3, and EP4) in the effect of PGE1 on the expression of these adhesion molecules using subtype-specific agonists. Among EP receptor agonists, EP2 and EP4 receptor agonists inhibited IL-18-elicited ICAM-1, B7.2, and CD40 expression. ONO-1301 (IP receptor agonist) prevented the expression of ICAM-1, B7.2, and CD40 regardless of the presence of IL-18 with the same potency as PGE1. The effect of a combination of ONO-1301 and 11-deoxy (D)-PGE1 (EP2/EP4 receptor agonist) on ICAM-1, B7.2, and CD40 expression mimicked that of PGE1. Moreover, PGE1 inhibited the production of IL-12 and interferon-gamma in PBMC in the presence and absence of IL-18, whereas PGE1 induced IL-10 production. In conclusion, IP receptor and EP2/EP4 receptor play an important role in the action of PGE1 on the expression of adhesion molecules on monocytes and cytokine production.

Induction of indirect donor-specific hyporesponsiveness by transportal RT1-peptide pulse in rat skin transplantation

In the present study, we examined whether transportal pulse of class I major histocompatibility complex (MHC) allopeptides can induce indirect (non-chimeric) donor-specific hyporesponsiveness, using a high-responder rat skin transplantation model. Two donor-specific 8-amino acid peptides corresponding to residues 58-65 and 70-77 in the alpha(1) helical region of RT1.A(a) were synthesized. In order to test immunogenicity of these peptides, mixed lymphocyte reaction (MLR) was performed. Then, 100-microg portions of peptides were injected into recipient Lewis (LEW, RT1.A(l)) rats via the portal vein 14 days before skin transplantation. Skin allografts from August Copenhagen Irish (ACI, RT1(a)) or Wistar King A (WKA, RT1(k), third-party) donors were transplanted to LEW (RT1(l)) recipients. Transportal pulse of residues 58-65 and 70-77 prolonged graft survival significantly in ACI-to-LEW skin transplantation (17.6+/-0.40 and 18.0+/-0.45 days) compared with control (14.2+/-0.37 days). However, pulse of residues 106-113, a non-donor-specific control, did not prolong graft survival time (14.6+/-0.40 days) in the same combination. Regarding the third-party donor, residues 58-65 injected into LEW recipients had no effect on survival time of skin grafts (19.0+/-0.84 days) derived from WKA donors compared with the untreated WKA-to-LEW control (19.4+/-0.93 days). Transportal pulse of RT1.A(a) peptides induced donor-specific hyporesponsiveness even in a high-responder rat skin transplantation model. Our results suggest that graft enhancement by transportal exposure to donor cells may not be induced by a chimeric process but, instead, by an indirect mechanism not involving intervention of viable donor cells.

Intraportal donor bone marrow transplantation improves intestinal allograft survival in rats under FK506-based immunosuppression

Donor-specific immunosuppression is important in transplant surgery. We examined the effect of intraportal donor-specific bone marrow transplantation on heterotopic small bowel transplantation in the high responder rat combination, ACI to Lewis. The study comprised five treatment groups: untreated controls (group 1); FK506 alone (group 2); low-dose predonine + FK506 (group 3); high-dose predonine + FK506 (group 4); and intraportal donor-specific bone marrow transplantation + FK506 (group 5). Intraportal transplantation was performed pre-operatively and FK506 and predonine given post-operatively. Intestinal allograft survival and changes of intragraft cytokine expression were analysed using the reverse transcription polymerase chain reaction. Allograft survival (mean +/- SD) was lowest in group 1 and greatest in group 5. The group 5 treatment regimen also down-regulated interferon-gamma and interleukin-2 transcription in the transplanted intestine. Intraportal donor bone marrow transplant combined with FK506 immunosuppression was found therefore to be the most beneficial treatment regimen.

Effect of prostaglandin E2 on intercellular adhesion molecule-1 and B7 expression in mixed lymphocyte reaction

BACKGROUND

The elevation of plasma interleukin (IL)-18 levels and the expression of intercellular adhesion molecule (ICAM)-1 and B7 on monocytes are involved in acute rejection. Prostaglandin (PG) E2 suppresses the rejection in animal transplantation models; however, little is known about its action mechanism. We examined the effect of PGE2 on the expression of ICAM-1 and B7 in the human mixed leukocyte reaction (MLR) in the presence or absence of IL-18.

METHODS

We measured the expression of ICAM-1, B7.1, and B7.2 on human monocytes by flow cytometry and determined the associated production of interferon-gamma and IL-12 by enzyme-linked immunosorbent assay. The modulatory effects of PGE2 and the relevant PGE2 receptor subtypes were characterized pharmacologically.

RESULTS

PGE2 inhibited the expression of ICAM-1, B7.1, and B7.2 on monocytes in MLR in a concentration-dependent manner. Whereas IL-18 significantly induced the expression of ICAM-1, B7.1, and B7.2 on monocytes in MLR and the production of interferon-gamma and IL-12, PGE2 inhibited these IL-18-initiated enhancements. The effects of PGE2 were mimicked by selective EP2 and EP4 agonists, but not by EP1 and EP3 agonists.

CONCLUSION

PGE2 strongly inhibited MLR with respect to the expression of ICAM-1, B7.1, and B7.2 via the EP2 and EP4 receptors, irrespective of the presence or absence of IL-18. In the previous study, histamine inhibited ICAM-1 expression in the presence of IL-18 but had no effect in the absence of IL-18. These results indicate that the inhibitory effect of PGE2 may be more general and stronger than that of histamine and may play an important role in future immunosuppressive strategies.

Activated T cells and soluble molecules in the portal venous blood of patients with cholestatic and hepatitis C virus-positive liver cirrhosis. Possible promotion of Fas/FasL-mediated apoptosis in the bile-duct cells and hepatocyte injury

We investigated the immune responses of patients with cholestatic and hepatitis C virus-positive (HCV-positive) liver cirrhosis by analysing T-cell subsets and cytokine levels in the portal and peripheral veins, using flow cytometry and enzyme-linked immunosorbent assay. In cholestatic liver cirrhosis, the proportion of natural-killer (NK) T cells and interleukin (IL) 6 and IL-18 levels in the portal venous blood were significantly higher than those in the peripheral venous blood. In HCV-positive liver cirrhosis, the proportions of NK T cells and Fas+ T cells and IL-6 and soluble Fas levels in the portal venous blood were significantly higher than those in the peripheral venous blood. These results suggest that in these diseases, activated T cells and soluble molecules in portal venous blood may promote Fas/FasL-mediated apoptosis of the bile-duct cells and hepatocytes, and contribute to the deterioration in liver function as an inevitable result of positive feedback.

[Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2001 and March 2002]

Isolated bacteria from infections in general surgery during the period from April 2001 to March 2002 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, four hundred and twenty strains were isolated from 175 (79.2%) of 221 patients with surgical infections. One hundred and eighty-six strains were isolated from primary infections, and 234 strains were isolated from postoperative infections. From primary infections, anaerobic Gram-positive bacteria were predominant, while from postoperative infections, aerobic Gram-positive bacteria were predominant. Among aerobic Gram-positive bacteria, although the isolation rate of Staphylococcus aureus was the highest, followed by that of Enterococcus faecalis from primary infections, the isolation rate of E. faecalis was the highest from postoperative infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae and Pseudomonas aeruginosa in this order, and from postoperative infections, P. aeruginosa was the most predominantly isolated, followed by Enterobacter spp., E. coli and Klebsiella spp. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both types of infections. The isolation rate of aerobic Gram-negative bacteria from primary infections and that of aerobic Gram-positive bacteria from postoperative infections were high in the last several years. We noticed no vancomycin-resistant Gram-positive cocci.

The analysis of the usefulness of laparoscopic microwave coagulation therapy for hepatocellular carcinoma in patients with poor hepatic reserve by serial measurements of IL-6, cytokine antagonists, and C-reactive protein

BACKGROUND

Little is known about the effectiveness of laparoscopic microwave coagulation therapy (L-MCT) for hepatocellular carcinoma (HCC) in patients with liver cirrhosis and poor hepatic reserve. Here, we analyzed the usefulness of laparoscopic MCT by comparing the serum levels of IL-6, cytokine antagonists, and C-reactive protein (CRP) following L-MCT with those following MCT with the open method (O-MCT).

METHODS

Sixteen patients with hepatocellular carcinoma (HCC) were separated into L-MCT and O-MCT groups according to ICGR15 (ICGR15 30%<:L-MCT, 30%> :O-MCT). Nine patients with poorer hepatic reserve received L-MCT, while seven patients with relatively good hepatic reserve received O-MCT. Serum levels of cytokine antagonists (interleukin-6, IL-6; interleukin-1 receptor antagonist, IL-1ra; soluble tumor necrosis factor receptor type I, sTNF-R55) and C-reactive protein (CRP) were simultaneously measured on serial postoperative days (POD) by immunoassay.

RESULTS

Postoperative serum levels of IL-6, IL-1ra, and CRP were significantly elevated on POD-1 and returned to the preoperative levels on POD-7 in both L-MCT and O-MCT groups. In contrast, no significant elevation of sTNF-R55 was found during the period in both groups. In addition, no statistical differences were found in the levels of IL-6, IL-1ra, sTNF-R, and CRP between the groups, except that the level of IL-6 on POD-1 in L-MCT group was significantly lower than that in the O-MCT group.

CONCLUSION

These results suggested that the surgical stress by L-MCT in patients with poorer hepatic reserve were almost equal to that by O-MCT in patients with relatively good hepatic reserve, indicating the usefulness of L-MCT for HCC patients with poorer hepatic reserve. We recommend the laparoscopic approach for future patients with the criterion that ICGR15 is over 30%.

Histamine inhibits lipopolysaccharide-induced tumor necrosis factor-alpha production in an intercellular adhesion molecule-1- and B7.1-dependent manner

Lipopolysaccharide (LPS) is recognized as a key molecule in the pathogenesis of Gram negative sepsis and septic shock. In the present study, we demonstrate that LPS (1-1000 pg/ml) concentration dependently up-regulated the expression of intercellular adhesion molecule (ICAM)-1, B7.1, and B7.2 on human monocytes using fluorescence-activated cell sorting analysis, and that tumor necrosis factor (TNF)-alpha production induced by LPS in peripheral blood mononuclear cells (PBMCs) was inhibited by the addition of antibodies against these adhesion molecules, suggesting the dependence of TNF-alpha production on cell-cell interaction through these adhesion molecules. Moreover, we found that histamine (10(-7)-10(-4) M) concentration dependently inhibited the expression of ICAM-1 and B7.1, but not B7.2 on monocytes induced by LPS. Histamine also inhibited the responses of TNF-alpha production induced by LPS. The modulatory effects of histamine on ICAM-1 and B7.1 expression and TNF-alpha production were all concentration dependently antagonized by famotidine but not by d-chlorpheniramine and thioperamide, and were mimicked by selective H2-receptor agonists but not by H1-, H3-, and H4-receptor agonists, indicating the involvement of H2-receptors in the histamine action. Dibutyryl cAMP down-regulated ICAM-1 and B7.1 expression on monocytes stimulated by LPS, suggesting the mediation by the cyclic adenosine monophosphate-protein kinase A pathway of H2-receptor activation. These results as a whole indicated that histamine via H2-receptor inhibited the LPS-induced TNF-alpha production through the regulation of ICAM-1 and B7.1 expression, leading to the reduction of innate immune response stimulated by LPS.

Effect of beta 2-adrenergic receptor stimulation on interleukin-18-induced intercellular adhesion molecule-1 expression and cytokine production

beta-Adrenergic receptor (AR) agonists have been demonstrated to modulate the production of inflammatory mediators. Recent studies implied that beta 2-AR agonists might be useful for chronic inflammatory diseases caused by interleukin (IL)-18. In the present study, we found that norepinephrine, epinephrine, or isoproterenol down-regulated IL-18 (100 ng/ml)-induced intercellular adhesion molecule (ICAM)-1 expression on monocytes in a dose-dependent manner (10(-8)-10(-4) M), but did not effect B7.1 and B7.2 expression after 24-h incubation. The modulatory effect of these catecholamines on ICAM-1 expression was antagonized by beta 2-AR antagonist, but not by alpha 1-, alpha 2-, or beta 1-AR antagonist. beta 2-AR-selective agonists salbutanol and terbutaline down-regulated IL-18-induced ICAM-1 expression on monocytes, but alpha 1-, alpha 2-, or beta1-AR agonist had no effect. In the same manner, salbutanol and terbutaline as well as norepinephrine, epinephrine, and isoproterenol regulated the IL-18-induced cytokine production, including IL-12, tumor necrosis factor-alpha or interferon-gamma through the stimulation of beta 2-AR. Together with the previous finding that ICAM-1/lymphocyte function-associated antigen-1 interaction plays a crucial role in the IL-18-initiated cytokine network, the present study strongly suggested that the stimulation of beta 2-AR inhibited the IL-18-activated cytokine cascade through the inhibitory effect on ICAM-1 expression, contributing to finding a new method for clinical treatment.

[Bacteria isolated from surgical infections and their susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2000 and March 2001]

Tendency of isolated bacteria from infections in general surgery and their antimicrobial susceptibilities during the period from April 2000 to March 2001 were investigated in a multicenter study in Japan, and the following results were obtained. The number of cases investigated as objectives was 234 for one year. A total of 388 strains (136 strains from primary infections and 252 strains from postoperative infections) were isolated from 165 cases (70.5% of total cases). In primary infections, anaerobic Gram-positive bacteria were predominant, while from postoperative infections, aerobic Gram-positive bacteria were predominant. Among aerobic Gram-positive bacteria, the isolation rate of Enterococcus faecalis was the highest, followed by that of Staphylococcus aureus from postoperative infections. Among anaerobic Gram-positive bacteria, the isolation rate of Peptostreptococcus spp. was the highest from both types of infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae and Pseudomonas aeruginosa in this order, and from postoperative infections, P. aeruginosa was the most predominantly isolated, followed by Enterobacter spp. and Klebsiella spp. Among anaerobic Gram-negative bacteria, the isolation rate of Bacteroides fragilis group was the highest from both types of infections. There was no vancomycin-resistant S. aureus nor Enterococcus spp. Among anaerobic bacteria, there were many resistant strains against penicillins and cephems with MICs higher than 100 micrograms/ml, and the same trend was observed among other Bacteroides spp. and Prevotella spp.

[Bacteria isolated from surgical infections and their susceptibilities to antimicrobial agents. Special references to bacteria isolated between April 1999 and March 2000]

The annual multicenter studies on isolated bacteria from infections in general surgery and their antimicrobial susceptibility have been conducted in Japan since July 1982. In this paper, the results obtained in the academic year 1999 (from April 1999 to March 2000) have been summarized. Two hundred seven cases were investigated, and 411 strains were isolated from 169 cases (81.6%). Of those strains, 184 and 227 strains were from primary infections and postoperative infections, respectively. In primary infections, the isolation rates of anaerobes, Streptococcus spp., and Escherichia coli were higher than in postoperative infections, while in postoperative infections, those of Gram-positive aerobes were higher than in primary infections. Staphylococcus aureus were most frequently isolated among Gram-positive aerobes, Peptostreptococcus prevotii among Gram-positive anaerobes, E. coli among Gram-negative aerobes, and Bacteroides fragilis among Gram-negative anaerobes. In primary infections, the percentage of Gram-negative aerobes, which gradually increased by the year 1998, decreased in the year 1999. The percentage of Gram-negative anaerobes increased, while that of Gram-negative bacteria was equivalent to that in the last year. In postoperative infections, the percentage of Gram-negative anaerobes, which continuously increased after the year 1990, decreased, while that of Gram-positive aerobes, which decreased in the last year, increased. Methicillin-resistant S. aureus accounted for 70.7% of S. aureus (41 strains). Either the number of strain or the percentage of MRSA decreased. The susceptibilities of E. coli and Klebsiella pneumoniae decreased against third and forth generation cephems, oxacephems, and monobactams. The susceptibilities of P. aeruginosa to carbapenems tend to decrease after the year 1997. S. aureus showed good susceptibilities to the tested drugs including arbekacin, vancomycin, and teicoplanin.

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.

Analysis of host response to hepatectomy by simultaneous measurement of cytokines in the portal vein, caval vein and radial artery

We analysed the host response to hepatectomy by simultaneous measurement of various cytokines and their antagonists in the portal vein, caval vein and radial artery in 10 patients with hepatocellular carcinoma. Concentrations of tumour necrosis factor-alpha (TNF), interleukin (IL) 1 beta, IL-2, IL-6, IL-10, soluble TNF receptor type I (sTNF-R), soluble IL-2 receptor (sIL-2R), IL-1 receptor antagonist (IL-1ra), soluble CD14 (sCD14) and endotoxin were determined just before and 1 h after hepatectomy. The values of IL-6, sTNF-R and IL-1ra were significantly increased after hepatectomy at each sampling site. In contrast, the levels of sIL-2R and sCD14 after hepatectomy were significantly decreased, and the levels of IL-1 beta, IL-2 and IL-10 were below the detection limits. Differences in cytokine concentrations between sampling sites revealed that the surgical stress of hepatectomy induced significant IL-1ra production in the liver and sTNF-R and IL-6 production in the lungs. These results suggest that hepatic resection is followed by the production of cytokine antagonists, such as IL-1ra, sTNF-R and IL-6, which could represent an important regulatory mechanism against surgical stress.

Prostaglandin E(2) inhibits IL-18-induced ICAM-1 and B7.2 expression through EP2/EP4 receptors in human peripheral blood mononuclear cells

Costimulatory molecules play important roles in immune responses. In the present study we investigated the effects of PGE(2) on the expression of ICAM-1, B7.1, and B7.2 on monocytes in IL-18-stimulated PBMC using FACS analysis. Addition of PGE(2) to PBMC inhibited ICAM-1 and B7.2 expression elicited by IL-18 in a concentration-dependent manner. We examined the involvement of four subtypes of PGE(2) receptors, EP1, EP2, EP3, and EP4, in the modulatory effect of PGE(2) on ICAM-1 and B7.2 expression elicited by IL-18, using subtype-specific agonists. ONO-AE1-259-01 (EP2R agonist) inhibited IL-18-elicited ICAM-1 and B7.2 expression in a concentration-dependent manner with a potency slightly less than that of PGE(2), while ONO-AE1-329 (EP4R agonist) was much less potent than PGE(2). The EP2/EP4R agonist 11-deoxy-PGE(1) mimicked the effect of PGE(2) with the same potency. ONO-D1-004 (EP1R agonist) and ONO-AE-248 (EP3R agonist) showed no effect on IL-18-elicited ICAM-1 or B7.2 expression. These results indicated that EP2 and EP4Rs were involved in the action of PGE(2). Dibutyryl cAMP and forskolin down-regulated ICAM-1 and B7.2 expression in IL-18-stimulated monocytes. As EP2 and EP4Rs are coupled to adenylate cyclase, we suggest that PGE(2) down-regulates IL-18-induced ICAM-1 and B7.2 expression in monocytes via EP2 and EP4Rs by cAMP-dependent signaling pathways. The fact that anti-B7.2 as well as anti-ICAM-1 Ab inhibited IL-18-induced cytokine production implies that PGE(2) may modulate the immune response through regulation of the expression of particular adhesion molecules on monocytes via EP2 and EP4Rs.

Essential role of ICAM-1/LFA-1 interaction in synergistic effect of IL-18 and IL-12 on IFN-gamma production in human PBMC

IL-18 (0-100 ng/ml) specifically upregulated ICAM-1 expression on monocytes in human PBMC as demonstrated in our previous study. In the present study, we examined whether the synergistic upregulation of ICAM-1 occurred after the stimulation with the combination of IL-18 and IL-12 and whether the synergistic production of IFN-gamma was dependent on the interaction between ICAM-1 on monocytes and LFA-1 on NK/T cells. The effect of IL-12 on ICAM-1 expression on monocytes was marginal even at the highest concentration (100 ng/ml). However, in the presence of IL-12 (100 ng/ml), the expression of ICAM-1 induced by IL-18 was significantly enhanced as compared with that obtained by IL-18 alone. In addition to the expression of ICAM-1 on monocytes, IFN-gamma production was synergistically stimulated by IL-18 and IL-12. Anti-ICAM-1 and anti-LFA-1 Abs exhibited significant inhibitory effect on enhanced production of IFN-gamma by the combination of two cytokines, in particular, anti-ICAM-1 showing the complete inhibition. These results as a whole indicated that synergistic effect of IL-18 and IL-12 on IFN-gamma production in human PBMC is ascribed to the synergism of the effect of two cytokines on ICAM-1 expression on monocytes and that the subsequent ICAM-1/LFA-1 interaction plays an important role in the enhanced production of IFN-gamma.

Effect of steroids on lipopolysaccharide/interleukin 2-induced interleukin 18 production in peripheral blood mononuclear cells

Interleukin (IL) 18, a powerful inducer of the immunoregulatory cytokine interferon-gamma (IFN-gamma), presents upstream of the cytokine activation cascade in the inflammatory response. The anti-inflammatory properties of steroids permit their use in various conditions, although effects are transient and pathological states are not fully relieved by short-term steroidal use. We examined the effect of lipopolysaccharide (LPS)/IL-2 on the cytokine cascade in human peripheral blood mononuclear cells (PBMCs). We also examined the effect of steroids on LPS/IL-2-induced cytokine production in human PBMCs taken from healthy volunteers. Cell-free supernatant fractions were assayed for IL-18, IL-12, IL-2, IFN-gamma and IL-10 protein, using enzyme-linked immunosorbent assays, and synergy between LPS and IL-2 in enhanced production of IL-18 was observed. Steroids suppressed the production of IL-18 and other secondary cytokines in LPS/IL-2-stimulated PBMCs, in a concentration- and time-dependent manner, although inhibition was incomplete even at high concentrations. Effects of steroid treatment on expression of membrane-bound LPS receptor antigen (mCD14) and intercellular adhesion molecule-1 (ICAM-1) in PBMCs were studied by flow cytometric analysis. Steroid treatment up-regulated mCD14 expression in a concentration-dependent manner, with no effect on ICAM-1 expression. These results suggest that the incomplete counteraction of steroids in the LPS/IL-2-initiating cytokine cascade is due, at least partly, to the up-regulation of mCD14 by steroid preparations, which increases susceptibility to bacterial endotoxins.

Differential cytokine response in host defence mechanisms triggered by gram-negative and gram-positive bacteria, and the roles of gabexate mesilate, a synthetic protease inhibitor

Bacterial infection results in the production of inflammatory mediators and may be involved in the pathogenesis of sepsis and/or systemic inflammatory response syndrome. The effect of lipopolysaccharide (LPS), a major component of the outer surface of Gram-negative bacteria, and Staphylococcal enterotoxin B (SEB), a superantigen of Gram-positive bacteria, on cytokine production in peripheral blood mononuclear cells (PBMCs) was examined. LPS significantly increased the production of proinflammatory and anti-inflammatory cytokines, and SEB enhanced the production of helper T lymphocyte type cytokines. These results illustrated the different responses to Gram-negative and Gram-positive bacterial infections. The effect of gabexate mesilate, a synthetic protease inhibitor, on cytokine production and expression of the toll-like receptor (TLR) was also examined. The results suggest that gabexate mesilate-induced inhibition of tumour necrosis factor-alpha (TNF-alpha) and interleukin-18 (IL-18) production in LPS-stimulated PBMCs is due to the inhibition of the nuclear factor-kappa B activation pathway and/or inhibition of the processing pathway of pro-TNF-alpha and pro-IL-18, not to down-regulation of TLR-2 or TLR-4.

Histamine regulation of interleukin-18-initiating cytokine cascade is associated with down-regulation of intercellular adhesion molecule-1 expression in human peripheral blood mononuclear cells

In the previous study, we demonstrated that interleukin (IL)-18 up-regulated intercellular adhesion molecule-1 (ICAM-1) expression on monocytes in human peripheral blood mononuclear cells (PBMC) and that heterotypic interaction between monocytes/T or NK cells through ICAM-1/LFA-1 intensified the production of IL-12, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) in PBMC. In the present study, we demonstrate that histamine inhibited the ICAM-1 expression in monocytes induced by IL-18 using flow cytometry and that the responses of IL-12, IFN-gamma, and TNF-alpha induced by IL-18 were concentration dependently inhibited by coexisting histamine, whereas IL-18-inhibited IL-10 production was reversed by the same concentrations of histamine. The modulatory effects of histamine on ICAM-1 expression and cytokine production were all concentration dependently antagonized by famotidine but not by d-chlorpheniramine and thioperamide, and were mimicked by selective H(2)-receptor agonists but not by H(1)- and H(3)-receptor agonists, indicating the involvement of H(2)-receptors in histamine action. The inhibition of IL-18-induced IFN-gamma by histamine was ascribed to the strong inhibition of IL-12 production by histamine. Histamine thus operates the negative feedback mechanism against IL-18-activated cytokine cascade through the strong inhibitory effect on ICAM-1 expression and IL-12 production in monocytes, contributing to the formation of diverse pattern of cytokine activation from Th1 to Th2, depending on the monocyte/macrophage activation and cytokine environment.

Post-operative adjuvant chemotherapy for colorectal cancer with 5-fluorouracil (5-FU) infusion combined with 1-hexylcarbamoyl-5-fluorouracil (HCFU) oral administration after curative resection

BACKGROUND

Although surgical resectability is an important prognostic factor, recurrences are commonly noted in advanced colorectal cancer patients, even after apparently curative surgery. Since such recurrences cannot be cured, better adjuvant chemotherapies are urgently required.

PATIENTS AND METHODS

We studied the effect of post-operative chemotherapy using oral administration of 1-hexylcarbamoyl-5-fluorouracil (HCFU) with 5-fluorouracil (5-FU) infusion for curatively-resected Stage IIIa and IIIb colorectal cancers. This study was prospectively randomized and controlled and 314 (97.8%) out of 321 patients were determined to be candidates for statistical assessment. Group A and Group B received 5-FU intravenous injection at, respectively, 333 mg/m2 and 1000 mg/m2 body surface area/24 hours continuously for 72 hours beginning on post-operative day 0 and day 6, with oral HCFU 300 mg daily for 52 weeks beginning 2 weeks after surgery.

RESULTS

There were no differences in overall 5-year survival or disease-free survival between Group A and Group B. A retrospective subset analysis. however, suggested that the protocol of Group B tended to yield better 5-year survival (68.3%) for rectal cancer than that of Group A (58.8%).

CONCLUSION

Inductive therapy with high-dose 5-FU in combination with oral HCFU appears to be beneficial as adjuvant chemotherapy for advanced rectal cancer with lymph node metastasis.