Metabolic regulation and microangiopathy in a cohort of Japanese IDDM-patients

In Caucasian patients with insulin-dependent diabetes mellitus (IDDM) proliferative diabetic retinopathy (PDR) and persistent proteinuria (PP) are associated, and major risk factors for development of microangiopathy have been identified. The aim of the present study was to evaluate whether these risk factors are also relevant and whether an association exists between the microangiopathic complications in Japanese IDDM-patients. A clinic-based cohort of 324 Japanese IDDM-patients was followed (a mean follow-up of 7 years). Annual examination for development of PDR and PP was performed. Fifty-eight patients developed PDR and 24 developed PP. Development of PDR was associated to high HbA1c-levels, i.e., the 4th quartile (RR 7.9, P < 0.0001), background retinopathy at admission (RR 9.9, P < 0.0001), high age at diabetes onset (RR 2.9, P < 0.0001) and female gender (RR 1.7, P < 0.05). Development of PP was associated to high HbA1c-levels (RR 2.8, P < 0.001) and background background retinopathy at admission (RR 7.9, P < 0.0001). The risk of developing PP was 9 times higher in patients developing PDR than in patients not developing PDR (P < 0.0001). The effect of metabolic control in our cohort was similar to that found in the DCCT and SDIS studies. In conclusion, development of PP is closely associated with PDR, also in Japanese IDDM-patients. The effect of metabolic control is the same as in Caucasian patients. Development of malignant angiopathy in IDDM-patients is not confined to Caucasian IDDM-patients, and the incidence rates are comparable to those found in Caucasian IDDM.

Expression of cytokine-induced neutrophil chemoattractant in rat cardiac myocytes

Accumulation and adhesion of leukocytes to cardiac myocytes play important roles in the pathogenesis of inflammation-mediated myocardial injury such as ischaemia/reperfusion and myocarditis. The involvement of leukocyte chemotactic factors has been speculated in these processes. We investigated the expression of cytokine-induced neutrophil chemoattractant (CINC) in rat cardiac myocytes. CINC is a rat equivalent of human interleukin-8. On exposure to interleukin-1 alpha (IL-1 alpha), cultured neonatal rat cardiac myocytes released appreciable levels of CINC both dose- and time-dependently. Tumor necrosis factor-alpha and lipopolysaccharide also significantly increased CINC accumulation in the culture supernatant. CINC mRNA expression was not observed in unstimulated myocytes, however, the expression was markedly induced by exposure to IL-1 alpha with a peak elevation at 3 h. Potent chemotactic activity for neutrophils was detected in the supernatant of cultured rat cardiac myocytes by stimulation with IL-1 alpha. This IL-1 alpha-induced chemotactic activity was significantly inhibited by polyclonal anti-CINC antiserum. Addition of dexamethasone, genistein, actinomycin D or cycloheximide significantly suppressed the IL-1 alpha-induced CINC accumulation. Under hypoxia (95%N2 + 5%CO2), CINC accumulation was increased in a time-dependent manner, and reoxygenation after hypoxia further intensified CINC accumulation. This hypoxia reoxygenation-induced CINC expression was significantly inhibited by pretreatment with dexamethasone. In conclusion, inflammatory stimuli induce the expression of CINC in rat cardiac myocytes, which may lead to myocardial injury via accumulation and activation of neutrophils.

Role of ADF/TRX and its inhibitor on the release of major basic protein from human eosinophils

Adult T cell leukemia-derived factor (ADF)/Thioredoxin (TRX), originally defined as an IL-2 receptor alpha-chain/p55 inducer, has many cytokine-like activities. We reported that the release of major basic protein (MBP) from mature eosinophils stimulated with cytochalasin B and C5a were augmented after preincubation with recombinant ADF/TRX. The addition of a TRX specific inhibitor, BE40644, suppressed the augmentation of MBP release from mature eosinophils. It is suggested that BE40644 is applicable in allergic diseases associated with eosinophils.

Expression of monocyte chemoattractant protein-1 in vascular tissue

We investigated monocyte chemoattractant protein-1 (MCP-1) mRNA expression in rat vascular smooth muscle cells (VSMC) and in human atherosclerotic arteries to test the involvement of MCP-1 in the pathogenesis of atherosclerosis. In Northern blot analysis, MCP-1 mRNA expression was not observed in unstimulated cultured rat vascular smooth muscle cells (VSMC), but its expression was clearly observed by exposure to tumour necrosis factor-alpha (100 U/ml) for 2-6 h. Mitogen-activated protein kinase activity in VSMC incubated in serum-free culture medium was increased by exposure to 0.5% fetal bovine serum, while the effect was significantly suppressed in the presence of MCP-1 (100 ng/ml). We then evaluated MCP-1 mRNA expression in atherosclerotic arteries obtained from 12 patients undergoing bypass revascularization through reverse transcription-polymerase chain reaction analysis and observed MCP-1 mRNA expression in all atherosclerotic arteries studied. These results support the premise that MCP-1 is secreted by VSMC in atherosclerotic plaques as well as by endothelial cells and macrophages and contributes to the pathogenesis of atherosclerosis.

Monocyte chemoattractant protein-1 stimulates tumor necrosis and recruitment of macrophages into tumors in tumor-bearing nude mice: increased granulocyte and macrophage progenitors in murine bone marrow

Monocyte chemoattractant protein-1 (MCP-1) belongs to the newly recognized "chemokine" superfamily of activation-inducible cytokines. We report here that MCP-1 gene-transferred mouse myeloma cells modulate tumor necrosis in myeloma-bearing nude mice. We established an MCP-1-producing myeloma cell line (X63-MCP-1) by transfection with human MCP-1 cDNA as well as interleukin-8-producing X63 cells (X63 IL-8). Each cell line showed the same growth characteristics in vitro, and 1 x 10(7) cells per mouse were injected into the peritoneal cavity resulting in the formation of tumors. Hematologic studies, including peripheral white blood cell counts and differentiation, showed no differences among the groups. They formed tumors in the same manner, which we observed from weeks 2.5 to 9. MCP-1 mice showed more tumor necrosis and infiltration of the macrophages into the tissue surrounding the tumor. In situ hybridization, using a partial cDNA as a probe, showed that macrophages contained MCP-1 mRNA. Bone marrow cell colony-forming assay showed a greater number of both granulocyte and macrophage colonies in MCP-1 mouse femur than in those of controls or interleukin-8 mice. MCP-1 has no direct stimulatory activity on stem cells, but longer exposure to MCP-1 in vivo might stimulate both granulocyte and macrophage progenitors and recruitment of macrophages into tumors, and it might explain the antitumor activity of macrophages in tumor-bearing nude mice.

Preparation of specific antibodies against murine IL-1ra and the establishment of IL-1ra as an endogenous regulator of bacteria-induced fulminant hepatitis in mice

Blocking monoclonal antibodies (mAbs) specific to mouse interleukin-1 receptor antagonist (IL-1ra) were prepared by immunizing Armenian hamsters with recombinant mouse IL-1ra. A sensitive and specific ELISA against mouse IL-1ra was also established. In Propionibacterium acnes-induced liver injury, P. acnes induced transient increase of serum tumor necrosis factor-alpha levels but not those of IL-1ra, IL-1, and IL-6. However, subsequent lipopolysaccharide (LPS) challenge induced the increase of serum levels of all these cytokines and the peak serum IL-1ra level was more than 20 times as high as serum IL-1 levels. Immunohistochemical analysis demonstrated that IL-1ra was predominantly produced by hepatocytes during the course of the priming phase by P. acnes and eliciting phase by LPS challenge. Furthermore, the administration of a mAb to mouse IL-1ra exacerbates the liver injury induced by P. acnes and sublethal dose of LPS, suggesting a protective role of endogenous IL-1ra in this liver injury model.

Chemokines in bronchoalveolar lavage fluid in summer-type hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a granulomatous interstitial lung disease caused by the inhalation of a variety of antigens and is characterized by a dramatic accumulation of inflammatory cells, including neutrophils, lymphocytes and macrophages, in the lung. The mechanisms implicated in the inflammatory cell recruitment observed in hypersensitivity pneumonitis are unknown. We examined the concentrations of two important chemokines, interleukin-8 (IL-8) and monocyte chemoattractant protein-1/monocyte chemotactic and activating factor (MCP-1/MCAF), in the bronchoalveolar lavage fluid (BALF) of patients with summer-type hypersensitivity pneumonitis (n = 8), and compared them with those in patients with sarcoidosis (n = 13) and with controls (n = 8). In the BALF of summer-type hypersensitivity pneumonitis, the levels both of IL-8 and MCP-1 were significantly increased compared with levels measured in control subjects. On the other hand, compared to the control value, the MCP-1 level in the BALF of the sarcoidosis patients was significantly increased, but IL-8 was only slightly and nonsignificantly increased. Since IL-8 is a chemoattractant for neutrophils and T-lymphocytes, whereas MCP-1 acts mainly on monocytes/macrophages, our findings may indicate that these two chemokines participate in the cellular accumulation observed in hypersensitivity pneumonitis.

Induction of monocyte chemoattractant protein-1 synthesis in human monocytes during transendothelial migration in vitro

Monocyte chemoattractant protein-1 (MCP-1, or monocyte chemotactic and activating factor) plays important roles in the recruitment of monocytes and thus in the development of atherosclerosis. In this study, we determined whether MCP-1 synthesis was induced by the cellular interaction between monocytes and endothelial cells during the process of transendothelial migration. We found that when human peripheral blood monocytes (2.5 x 10(6) cells) and umbilical vein endothelial cells (HUVECs; 5.0 x 10(5) cells) were cocultured for 5 hours, 7.9 ng/mL MCP-1 was secreted into the medium, whereas when the two were cultured separately, MCP-1 levels were 1.0 and 0.9 ng/mL, respectively. Furthermore, the use of interleukin-1 beta (IL-1 beta)-pretreated HUVECs in cocultures induced twice the levels of MCP-1 as in unstimulated HUVEC culture. Conditioned medium had transendothelial chemotactic activity for monocytes, and this activity was completely abolished by addition of anti-MCP-1 antibody. Although MCP-1 mRNA levels were very low or undetectable in HUVECs or monocytes alone, message could be detected after 2 hours of coculture in total mRNA preparations from both monocytes and HUVECs. mRNA levels increased by 4 hours and had declined slightly by 24 hours. The rapid induction of message suggests that cell contact between monocytes and HUVECs induces the de novo synthesis of MCP-1 protein. Anti-interleukin (IL)-1 alpha/beta and anti-tumor necrosis factor-alpha antibodies, or anti-lymphocyte function-associated antigen-1 and very late antigen-4 antibodies, had little or no inhibitory effects on MCP-1 secretion by cocultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical localization of Na(+)-dependent glucose transporter in the rat digestive tract

Glucose is actively absorbed in the intestine by the action of the Na(+)-dependent glucose transporter. Using an antibody against the rabbit intestinal Na(+)-dependent glucose transporter (SGLT1), we examined the localization of SGLT1 immunohistochemically along the rat digestive tract (oesophagus, stomach, duodenum, jejunum, ileum, colon and rectum). SGLT1 was detected in the small intestine (duodenum, jejunum and ileum), but not in the oesophagus, stomach, colon or rectum. SGLT1 was localized at the brush border of the absorptive epithelium cells in the small intestine. Electron microscopical examination showed that SGLT1 was localized at the apical plasma membrane of the absorptive epithelial cells. SGLT1 was not detected at the basolateral plasma membrane. Along the crypt-villus axis, all the absorptive epithelial cells in the villus were positive for SGLT1, whose amount increased from the bottom of the villus to its tip. On the other hand, cells in the crypts exhibited little or no staining for SGLT1. Goblet cells scattered throughout the intestinal epithelium were negative for SGLT1. These observations show that SGLT1 is specific to the apical plasma membrane of differentiated absorptive epithelial cells in the small intestine, and suggest that active uptake of glucose occur mainly in the absorptive epithelial cells in the small intestine.

Effects of endogenous endothelial interleukin-8 on neutrophil migration across an endothelial monolayer

OBJECTIVE

Recent studies suggest that interleukin-8 (IL-8) is involved in the neutrophil infiltration of subendothelial myocardial tissue in the ischaemia/reperfusion injury associated with acute myocardial infarction. The aim of this study was to investigate the effects of IL-8 on transendothelial neutrophil migration using an in vitro three dimensional double chamber migration assay system.

METHODS

Human neutrophils were incubated with human endothelial cell monolayers for 1 h, and adherent and migrated neutrophils were then counted. Expression of IL-8 mRNA and secretion of its protein by endothelial cells were analysed respectively by northern blotting and ELISA.

RESULTS

Recombinant human (rh) IL-8 (50 ng.ml-1) placed in the lower compartment significantly increased neutrophil adhesion 1.7-fold and transmigration 2.3-fold, compared with control conditions using medium alone in both compartments. In contrast, rh IL-8 (50 ng.ml-1) in the upper compartment significantly inhibited neutrophil adhesion and transmigration by 53% and 61% respectively compared with controls. Neutrophil adhesion and transmigration was dependent on the IL-8 concentration gradient between upper and lower compartments. Unstimulated endothelial cells showed no IL-8 expression, but endothelial cells pretreated with IL-1 beta (25 U.ml-1) markedly induced endogenous IL-8 mRNA and protein accumulation. When endothelial cells were cocultured with neutrophils, enhanced endogenous IL-8 production was observed. Pretreatment of endothelial cells with IL-1 beta for 4 and 24 h increased neutrophil transmigration 2.8-fold and 3.0-fold respectively, compared with unstimulated endothelial cells. The addition of anti-IL-8 monoclonal antibody (12.5 micrograms.ml-1) to the upper compartment with IL-1 beta-pretreated endothelial cells further enhanced transmigration from 2.8- to 3.3-fold and from 3.0- to 4.3-fold respectively.

CONCLUSIONS

Endogenous endothelial IL-8, secreted from activated endothelial cells into the apical side of endothelial cell monolayers, has an inhibitory effect on transendothelial migration of neutrophils, suggesting that IL-8 may prevent excessive neutrophil infiltration of myocardial tissue from circulating blood in the reperfusion injury associated with acute myocardial infarction.

Suppressive role of endogenous endothelial monocyte chemoattractant protein-1 on monocyte transendothelial migration in vitro

Monocyte chemoattractant protein-1 (MCP-1, or monocyte chemotactic and activating factor) is thought to play an important role in monocyte infiltration into tissue, but little is known about its effect on monocyte-endothelium interaction. We examined the effect of MCP-1 produced by cytokine-activated endothelial cells (ECs) on monocyte-endothelium adhesion and subsequent transendothelial migration by using a double-chamber vessel model. Unstimulated ECs showed no MCP-1 expression, but exposure to interleukin-1 beta (IL-1 beta, 25 U/mL) induced marked MCP-1 mRNA expression and protein synthesis. When placed in the lower compartment, recombinant human (rh) MCP-1 (100 ng/mL) produced a 1.9-fold and a 2.7-fold increase in adhesion and migration, respectively, compared with a corresponding 51% and 59% decrease when placed in the upper compartment. Migration of monocytes was dependent on a gradient of rh-MCP-1 from the apical to basilar side of the EC layer. Furthermore, a forward gradient of MCP-1 induced adherent cells to increase their subsequent migration, whereas a reverse gradient induced the cells to detach and completely inhibited their subsequent migration. Pretreatment with IL-1 beta for 4 and 24 hours produced a 20% and 63% increase in monocyte migration, respectively. In the presence of anti-MCP-1 antibody, the increase was further enhanced by 52% and 152%, respectively. These results suggest that endogenous endothelial MCP-1, when secreted by IL-1-stimulated ECs, suppresses monocyte migration in the presence of MCP-1 on the basilar side of the EC layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppressive effects of central opioids on delayed type hypersensitivity to trinitrochlorobenzene: comparative study with morphine and electroacupuncture

We reported previously that electroacupuncture (Acu) applied to the acu-point equivalent to GV4 in the mouse just before the 2,4,6-trinitrochlorobenzene (TNCB) challenge suppressed the delayed type hypersensitivity (DTH) through endogenous opioidergic systems in the brain, and the pituitary was pivotal in this immunosuppression. The purpose of the present study was to compare the suppressive effects of Acu with those of single, acute doses of morphine on TNCB-DTH in intact and hypophysectomized (HPX) mice. Subcutaneous morphine 10 mg/kg in ddY mice, 30 mg/kg in BALB/c mice or intracisternal morphine 40 micrograms/mouse in BALB/c mice given just before TNCB challenge suppressed (40-53%) the maximal extent of ear swelling at 24 hrs after challenge in intact mice. In HPX mice, the suppressive effects of intracisternal morphine 10 and 100 micrograms/mouse were less pronounced than those observed in intact mice and there was no significant difference between intact and HPX groups. In addition, suppressive effects observed with Acu or subcutaneous morphine (30 mg/kg) were effectively antagonized by pretreatment with intracisternal naloxone at a dose of as low as 2 micrograms/mouse. Naloxone alone had no effect of its own. These results suggest that 1) the activation of opioid receptor-mediated pathways in the brain, which occurs when opioids are endogenously released (Acu) or exogenously given (morphine), is important in the suppression of TNCB-induced DTH, a cell-mediated immune response, and 2) the pituitary is less pivotal in the suppressive effects of acute morphine than in those of Acu.

Expression of leukocyte chemotactic cytokines in myocardial tissue

Cytotoxic action of leukocytes may be involved in the pathogenesis of inflammatory heart muscle disorders. We investigated the expression of rat leukocyte chemotactic cytokines--cytokine induced neutrophil chemoattractant (CINC) and JE--in cultured neonatal rat cardiac myocytes; CINC belongs to the interleukin 8 (IL-8) family and JE is a homologue of human monocyte chemoattractant protein 1 (MCP-1). In Northern blot analysis, CINC and JE transcripts were not clearly observed in unstimulated rat cardiac myocytes. However, their expression was clearly observed after exposure to tumour necrosis factor-alpha (TNF-alpha; 100 U/ml) for 2-6 h. We then evaluated IL-8 and MCP-1 mRNA expression in human endomyocardial biopsy specimens from seven patients with idiopathic dilated cardiomyopathy by polymerase chain reaction analysis. Both IL-8 and MCP-1 mRNA transcripts were recognized in all patients studied. These results show for the first time that leukocyte chemotactic cytokines, IL-8 and MCP-1, are expressed in myocardial tissue, which might contribute to the pathogenesis of inflammatory heart muscle disorders.

Monocyte chemoattractant protein 1 inhibits growth of rat vascular smooth muscle cells

The early atherosclerotic lesion is characterized by the migration of inflammatory cells, including monocytes, which may serve as a source of cytokines such as monocyte chemoattractant protein 1 (MCP-1), a homologue of mouse JE. We investigated the effect of MCP-1 on the growth of vascular smooth muscle cells (VSMC) isolated from rat aortae. In Northern blot analysis, MCP-1/JE transcripts were not observed in unstimulated VSMC, but its expression was clearly observed by exposure to lipopolysaccharide (1 micrograms/ml) for 6 h. Human recombinant MCP-1 inhibited the uptake of [3H]thymidine by VSMC cultured in 0.5% fetal bovine serum (FBS) containing Dulbecco's modified Eagle's medium (DMEM) in a dose-dependent manner. The inhibitory effect of MCP-1 on the growth of VSMC was also confirmed by a change in cell counts. The antiproliferative effect of MCP-1 was significantly blocked in the presence of an anti-MCP-1 antibody. MCP-1-induced inhibition of [3H]thymidine uptake was not affected in the presence of indomethacin (1 micrograms/ml) or NG-monomethyl-L-arginine (0.1 mM), and MCP-1 showed no effect on 6-ketoprostaglandin F1 alpha, guanosine 3',5'-cyclic monophosphate, and adenosine 3',5'-cyclic monophosphate syntheses in VSMC. These results indicate that MCP-1 inhibits the proliferation of VSMC in vitro and that its effect is independent of prostaglandin or nitric oxide generation.

Mechanisms of eosinophilia in BALB/c-nu/+ and congenitally athymic BALB/c-nu/nu mice infected with Toxocara canis

We studied the mechanism of eosinophilia in BALB/c-nu/+ (nu/+) and BALB/c-nu/nu (nu/nu) mice infected with Toxocara canis. Eosinophilia with two peaks on days 11 and 21 of infection was observed in infected nu/+ mice, and with a peak on day 11 in nu/nu mice. Interleukin-5 (IL-5) mRNA was expressed on day 5 of infection in the lung and spleen of nu/+ mice and in the lung of nu/nu mice, but not in the spleen of nu/nu mice. Large numbers of eosinophils and lymphocytes infiltrated the lung of both mice 1 week after infection. The number of larvae in the lung was the largest on day 5. Anti-IL-5 monoclonal antibody (mAb) treatment completely inhibited eosinophilia of both mice, with no change of larval distribution. Administration of anti-CD4 or anti-CD3 mAb markedly reduced the second peak of eosinophilia on day 21 of infection in nu/+ mice, and slightly reduced the first peak of eosinophilia on day 11 in both mice. Anti-CD8 mAb had no effect on the eosinophilia. These results suggest that eosinophilia in both mice is caused by IL-5, and that IL-5 is produced by cells other than CD4+ T cells, in addition to CD4+ T cells.

Molecular analysis of the cytokine network involved in cachexia in colon 26 adenocarcinoma-bearing mice

Two clones, one cachexigenic (clone 20) and the other noncachexigenic (clone 5), from a murine colon adenocarcinoma, colon 26 cells, were used to analyze the involvement of immune reactions as well as the cytokine network in cachexia. Clone 20 induced cachexia in nude and SCID mice as well as in normal BALB/c mice, suggesting that lymphocytes played little, if any, role in the process. Both clones failed to express mRNA of interleukin (IL) 1 alpha, IL-1 beta, IL-6, and tumor necrosis factor alpha in vitro with or without the coculture of NIH3T3 cells or spleen cells. However, IL-6 mRNA was selectively detected at the tumor site of clone 20 but not at that of clone 5-bearing mice. In contrast, tumor necrosis factor alpha mRNA was detected at tumor sites and in spleens of only clone 5-bearing mice, suggesting a potential role of IL-6, but not tumor necrosis factor alpha, in inducing cachexia. Anti-IL-6 antibody partially reversed the weight loss induced by clone 20, whereas the continuous infusion of IL-6 failed to cause weight loss, despite being associated with an elevation of a serum acute phase protein. These results suggest that IL-6 is necessary but not sufficient for the induction of cachexia. Both clones expressed IL-6 mRNA in the presence of IL-1 in vitro, and mice bearing either clone expressed IL-1 beta mRNA at the tumor site. Moreover, IL-1 receptor antagonist (IL-1Ra) mRNA was detected at the tumor site of clone 5-bearing mice but not at that of clone 20-bearing mice, suggesting that IL-1Ra might block IL-1 activity to reduce IL-6 production in clone 5-bearing mice. However, the transfection of clone 20 with IL-1Ra cDNA failed to abolish its capacity to produce IL-6 and to cause cachexia. Collectively, additional factor(s) besides IL-1Ra and IL-1 beta may control IL-6 and some other cachexigenic factor production, thereby causing cachexia in this model.

Chemotactic agonists induce cytokine generation in eosinophils

Recent studies have shown that eosinophils are capable of generating and releasing cytokines, providing a novel biologic aspect of eosinophils for regulating allergic inflammation by an autocrine or paracrine mechanism. Eosinophils synthesize various cytokines; however, the physiologic stimuli that trigger eosinophils to generate cytokines have not been fully elucidated. We examined the effect of chemotactic agonists on eosinophil cytokine generation by employing the determination of IL-8 as the main parameter. Both C5a and FMLP stimulated eosinophils to release IL-8, whereas platelet-activating factor and C-C chemokines did not exert any significant effects. On a molar basis, C5a was two orders of magnitude more potent than FMLP. The generation of IL-8 by chemoattractants was absolutely dependent on the presence of cytochalasin B. Pertussis toxin completely attenuated C5a- and FMLP-induced IL-8 production, indicating the involvement of pertussis toxin-sensitive G-proteins in the signal-transduction process leading to these responses. Experiments of in situ hybridization and PCR amplification revealed that both C5a and FMLP promoted eosinophil IL-8 production through transcriptional gene activation. Pyrrolidine dithiocarbamate completely abrogated chemoattractant-induced IL-8 production, indicating the involvement of NF-kappa B in the cytoplasmic/nuclear signal-transduction process. Furthermore, chemoattractant-induced cytokine production was not limited to IL-8; C5a and FMLP but not platelet-activating factor induced significant secretion of granulocyte-macrophage-CSF from eosinophils. These results indicate that C5a and FMLP stimulate eosinophils to elaborate cytokines, which could be an important mechanism in the regulation of allergic inflammation.

Chemotactic agonists induce cytokine generation in eosinophils

Recent studies have shown that eosinophils are capable of generating and releasing cytokines, providing a novel biologic aspect of eosinophils for regulating allergic inflammation by an autocrine or paracrine mechanism. Eosinophils synthesize various cytokines; however, the physiologic stimuli that trigger eosinophils to generate cytokines have not been fully elucidated. We examined the effect of chemotactic agonists on eosinophil cytokine generation by employing the determination of IL-8 as the main parameter. Both C5a and FMLP stimulated eosinophils to release IL-8, whereas platelet-activating factor and C-C chemokines did not exert any significant effects. On a molar basis, C5a was two orders of magnitude more potent than FMLP. The generation of IL-8 by chemoattractants was absolutely dependent on the presence of cytochalasin B. Pertussis toxin completely attenuated C5a- and FMLP-induced IL-8 production, indicating the involvement of pertussis toxin-sensitive G-proteins in the signal-transduction process leading to these responses. Experiments of in situ hybridization and PCR amplification revealed that both C5a and FMLP promoted eosinophil IL-8 production through transcriptional gene activation. Pyrrolidine dithiocarbamate completely abrogated chemoattractant-induced IL-8 production, indicating the involvement of NF-kappa B in the cytoplasmic/nuclear signal-transduction process. Furthermore, chemoattractant-induced cytokine production was not limited to IL-8; C5a and FMLP but not platelet-activating factor induced significant secretion of granulocyte-macrophage-CSF from eosinophils. These results indicate that C5a and FMLP stimulate eosinophils to elaborate cytokines, which could be an important mechanism in the regulation of allergic inflammation.

Specific increase in interleukin-8 concentrations in dialysis fluid of patients with peritonitis receiving continuous ambulatory peritoneal dialysis

AIMS

To evaluate the influence of interleukin-8 (IL-8) and other inflammatory cytokines (IL-6, IL-1 beta and tumour necrosis factor alpha (TNF alpha)) on the occurrence of peritonitis in patients receiving continuous ambulatory peritoneal dialysis (CAPD).

METHODS

The study population comprised 12 patients with peritonitis, 33 without peritonitis, all undergoing CAPD, and five patients undergoing peritoneal catheter implantation. Cytokine concentrations in dialysis fluid were determined by immunoassay and their values compared.

RESULTS

Concentrations of both IL-8 (median 147 pg/ml, range 20-2273 pg/ml; n = 12) and IL-6 (median 1120 pg/ml, range 96-10,600 pg/ml) were substantially elevated, while the IL-1 beta concentration was lower and TNF alpha was not detectable in patients at diagnosis. The IL-6 concentration was also elevated in patients undergoing catheter implantation as well as in those with peritonitis. The IL-8 concentration, however, was elevated only upon infection. Intraperitoneal production of IL-8 was evident on determination of paired serum and dialysis fluid cytokine concentrations, and immunostaining of peritoneal cells with monoclonal anti-IL-8 antibody.

CONCLUSIONS

These results suggest that determination of the IL-8 concentration in dialysis fluid maybe useful as a specific marker for following patients with peritonitis receiving CAPD.

Induction of eosinophil cytokine generation by chemoattractants

Recent studies have shown that eosinophils are capable of generating and releasing cytokines, illustrating a novel biologic aspect of eosinophils in regulating allergic inflammation by either autocrine or paracrine mechanisms. The effect of chemotactic agonists on eosinophil cytokine generation was examined by determination of interleukin-8 (IL-8) as a main parameter. Both complement C5a and N-formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated eosinophils to release IL-8, but platelet activating factor (PAF) did not exert any significant effects. The generation of IL-8 by chemoattractants was absolutely dependent on the presence of cytochalasin B. Pertussis toxin completely attenuated C5a- and FMLP-induced IL-8 production, indicating the involvement of pertussis toxin-sensitive G proteins in the signal transduction process. In situ hybridization showed that both C5a and FMLP promoted eosinophil IL-8 production via transcriptional gene activation. Furthermore, C5a and FMLP, but not PAF, induced significant secretion of granulocyte-macrophage colony-stimulating factor from eosinophils. These results indicate that C5a and FMLP stimulate eosinophils to elaborate cytokines, which could be an important mechanism in the regulation of allergic inflammation.

Detection and localization of interleukin-8 mRNA and protein in human placenta and decidual tissues

It has been reported that interleukin-8 (IL-8) is secreted from the placental and decidual tissues and that IL-8 levels in the amniotic fluids are significantly elevated by chorioamnionitis or labor pain. The present study was aimed at defining the localization of IL-8 mRNA as well as IL-8 protein at the feto-maternal interface using in situ hybridization and immunohistochemical staining. Both IL-8 mRNA and protein were localized in cytotrophoblast, syncytiotrophoblast and Hofbauer cells of the placenta, decidual stromal cells, decidual lymphocytes and endometrial gland cells. IL-8 secretion from glandular cells has not previously been reported. In addition, we confirmed IL-8 mRNA expression and secretion of IL-8 by an endometrial cancer cell line (Ishikawa) using the reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) methods, respectively.

Changes of QRS axis in transient myocardial ischaemia induced by percutaneous transluminal coronary angioplasty

The QRS axis of 130 consecutive patients with coronary artery disease undergoing percutaneous transluminal coronary angioplasty (PTCA) were measured before balloon inflation and just before balloon deflation. Patients were divided into two groups. Group A (103) had angina pectoris and/or non-transmural old myocardial infarction with no abnormal Q waves; group B (27) had an old transmural myocardial infarction with abnormal Q waves. In group A, the QRS axis had significantly shifted to the left in patients with left anterior descending artery (LAD) occlusion (from 68.0 +/- 42.7 degrees to 40.2 +/- 44.6 degrees, P < 0.001); however in those patients without involvement of the major septal branch, significant axis changes were not observed (from 53.6 +/- 34.1 degrees to 49.8 +/- 33.1 degrees). When the right coronary artery (RCA) was occluded in group A, the QRS axis shifted to the right significantly (from 63.2 +/- 40.0 degrees to 89.8 +/- 30.1 degrees. P < 0.01); during left circumflex artery (LCX) occlusion, no significant axis shift was observed. In group B, no significant axis shift was observed either in patients with occlusion of the LAD or the RCA. It is concluded that transient left axis deviation reflects an obstructive lesion of the proximal portion of the LAD with involvement of the major septal branch, and transient right axis deviation reflects an obstructive lesion of the RCA.