Improved preparation of leukocytes for chemiluminescent study of human phagocytic leukocyte-generated reactive oxygen species

Anti-inflammatory effect of granulocyte and monocyte adsorption apheresis in a rabbit model of immune arthritis

In active rheumatoid arthritis, large numbers of granulocytes and macrophages are found in the inflamed joints. These leucocytes can promote inflammation and tissue injury by releasing inflammatory cytokines, proteinases and oxygen derivatives. To see if granulocyte and monocyte (GM) depletion produces anti-inflammatory effect, GM adsorption apheresis was performed in rabbits with immune arthritis by using a column (Adacolumn) filled with cellulose diacetate beads (G-1 beads) as adsorptive carriers which selectively adsorb CD11b positive GMs. Injection of ovalbumin into the knee joints of ovalbumin-sensitized rabbits caused a marked increase in peripheral blood leucocytes, joint swelling, increased granulocyte adhesion to G-1 beads and elevated TNF-alpha production by peripheral blood mononuclear cells (PBMC). When rabbits received a 60 min adsorption apheresis, there was suppression of CD11b positive leucocyte infiltration into the joint and reduced joint swelling (P < 0.01) compared with controls. Additionally, there was a significant (p < 0.01) suppression of TNF-alpha production by PBMC in the post column blood. These results suggest that GM depletion may serve as a non-pharmacological strategy to modify inflammatory disorders.

Is the neutrophil reactive oxygen species production measured by luminol and lucigenin chemiluminescence intra or extracellular? Comparison with DCFH-DA flow cytometry and cytochrome c reduction

BACKGROUND

Polymorphonuclear neutrophils (PMNs) are crucial in host defense against invading microorganisms through reactive oxygen species (ROS) production. However, generated ROS released in excess into media can damage the host tissue. It is therefore essential, when exploring oxygen species production, to discriminate between its intracellular (IC) and extracellular (EC) localization. Several methods of ROS detection are commonly used. However, the literature shows that it is not always clear whether the species detected are IC or EC, especially with the chemiluminescence technique.

METHODS

We compared PMN ROS production, determined by chemiluminescence, using two different probes (luminol and lucigenin) with that measured by 2'-7'-dichlorofluorescin diacetate (DCFH-DA) flow cytometry for IC production and by cytochrome c reduction for EC production.

RESULTS

We found that luminol-dependent chemiluminescence explored IC ROS production more specifically (r=0.77, p<0.01: correlation between luminol-amplified chemiluminescence and DCFH-DA flow cytometry). Lucigenin-amplified chemiluminescence and cytochrome c reduction were closely related (r=0.55, p<0.01).

CONCLUSION

Luminometry detection can thus afford reproducible information on intracellular ROS kinetic production using luminol and extracellular ROS detection using lucigenin, simply and at low cost.

Safety and efficacy of granulocyte and monocyte adsorption apheresis in patients with active ulcerative colitis: a multicenter study

Active ulcerative colitis (UC) is characterized by activation and infiltration of granulocytes and monocytes/macrophages into the colonic mucosa. The infiltrated leukocytes can cause mucosal damage by releasing degradative proteases, reactive oxygen derivatives, and proinflammatory cytokines. The aim of this trial (conducted in 14 specialist centers) was to assess safety and efficacy of granulocyte and monocyte adsorption apheresis in patients with active UC most of whom were refractory to conventional drug therapy. We used a new adsorptive type extracorporeal column (G-1 Adacolumn) filled with cellulose acetate beads (carriers) of 2 mm in diameter, which selectively adsorb granulocytes and monocytes/macrophages. Patients (n = 53) received five apheresis sessions, each of 60 minutes duration, flow rate 30 ml per minute for 5 consecutive weeks in combination with 24.4 +/- 3.60 mg prednisolone (mean +/- SE per patient per day, baseline dose). During 60 minutes apheresis, 26% of granulocytes, 19.5% of monocytes and 2% of lymphocytes adsorbed to the carriers. At week 7, 58.5% of patients had remission or improved, the dose of prednisolone was reduced to 14.2 +/- 2.25 mg (n = 37). The apheresis treatment was fairly safe, only eight non-severe side effects (in 5 patients) were reported. Based on our results, we believe that in patients with active severe UC, patients who are refractory to conventional drugs, granulocyte and monocyte adsorption apheresis is a useful adjunct to conventional therapy. This procedure should have the potential to allow tapering the dose of corticosteroids, shorten the time to remission and delay relapse.

Adenosine 5'-diphosphate as a factor in platelet aggregation induced by human plasma remnant lipoproteins

The action of lipoprotein lipase on chylomicrons (CM) and very low density lipoproteins (VLDL) produces remnant lipoproteins (RLP) which are rich in triglycerides, cholesterol and apolipoprotein E (apo E). Apo E serves as a ligand for uptake of RLP by macrophages, platelets, endothelial cells and other cells expressing the LDL-receptor or the remnant receptor, thus having a major role in the clearance of plasma cholesterol and triglycerides, but at the same time, uptake of apo E-bearing RLP can profoundly alter the physiology of these cells and promote atherosclerosis. Like RLP, blood platelets also have roles in atherosclerosis and thrombosis, hence it is likely that RLP influence platelet activity as well. RLP derived from normal human plasma VLDL and CM were prepared using two monoclonal antibodies, anti-apo B-100 (JI-H) and anti-apo A-I (H-12) coupled to Sepharose 4B gel to form an immunoaffinity column. Lipoproteins containing apo B-100 including VLDL and LDL adsorb to (JI-H)-gel, while CM and HDL with apo A-I adsorb to (H-12)-gel. The particles in the unbound fraction (RLP) are rich in apo B-48, apo E and apo B-100 containing particles with multiple molecules of apo E. The RLP fraction with a total triglyceride of 14+/-3.2 mg/ml; cholesterol, 0.39+/-0.1 mg/ml and protein, 0.78+/-0.24 mg/ml (n=19) was added to aliquots of blood of man, rabbits, guinea pigs, mice, and rats at protein equivalents of 0.98 to 78 microg/ml blood and agitated gently at 37 degrees C for 40 sec. Platelet aggregation was measured as a fall in single platelet count. RLP induced aggregation of platelets in man (p<0.005) rabbit (p<0.0005), guinea pig (p<0.002) and mouse (p<0.0001), but no RLP induced platelet aggregation was observed in the rat blood. Scanning electron microscopy revealed that in the presence of RLP, platelets had adhered to and formed aggregates on red cells. The platelet response to RLP was inhibited by apyrase known to scavenge ADP, by 5 microM 2-chloroadenosine, a platelet ADP receptor antagonist and by 3.4 microM cilostazol, a phosphodiesterase type III inhibitor known to raise cyclic AMP level in platelets. It is thought that RLP cause leakage of ADP from red cells which then mediates platelet aggregation.

A role for granulocyte and monocyte apheresis in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory condition, the etiology of which is not well understood. Recent reports indicate a major role of granulocytes in the pathogenesis of RA; arthritic joints are infiltrated with phagocytic leukocytes, granulocytes, and monocytes/macrophages, and it is believed that these cells, by releasing degradative proteinases, cytokines, and reactive oxygen species, contribute to joint destruction. Hence, the apheresis of granulocytes and monocytes may benefit patients with RA. Granulocyte and monocyte apheresis was carried out in 143 patients with RA using an apheresis column (G-1) packed with 220 g cellulose acetate beads, which selectively adsorb granulocytes and monocytes. Patients received 1 or 2 apheresis sessions, each of 1 h duration per week over a 4 week period at a flow rate of 30 ml/min. Apheresis significantly reduced swollen and tender joint counts and the duration of morning stiffness, and it increased grip strength, together with suppression of tumor necrosis factor-alpha and interleukin-1beta production by peripheral blood monocytes. It is concluded that this alternative treatment induces a kind of immunomodulation.

Effect of plaunotol on gastric injury induced by ischaemia-reperfusion in rats

Plaunatol, an anti-ulcer drug, increases prostaglandin content in gastric tissue but its effect on radical-mediated gastric damage or activity against reactive oxygen species is unknown. We examined the effects of oral administration of plaunotol (Kelnac) on the acute gastric mucosal lesion and its progression to ulcer lesion induced by ischaemia-reperfusion in rats. Plaunotol (30 and 100 mg kg-1, 15 min before ischaemia) significantly reduced the total erosion area observed immediately after ischaemia-reperfusion. When plaunotol (30 and 100 mg kg-1, once a day) was administrated orally 60 min after reperfusion, it prevented the progression from erosion to ulcer. At 72 h after ischaemia-reperfusion, the total area of ulcers lesions was significantly reduced compared with that without plaunotol administration. Furthermore, treatment with plaunotol (100 mg kg-1) significantly increased prostaglandin E2 content in gastric tissues of both acute gastric mucosal lesion and gastric ulcer lesion. In in-vitro experiments, plaunotol (1-3 mg mL-1) reduced the superoxide radicals generated by leucocytes, but not by xanthine oxidase. These results indicate that plaunotol has protective effects on both the onset of acute gastric mucosal injury and its progression to ulcer lesion induced by ischaemia-reperfusion. Both effects of plaunotol on increase in prostaglandin content in gastric tissues and inhibition of superoxide radical from leucocytes may play important roles on the protection against gastric mucosal injury.

Granulocytapheresis in the treatment of patients with rheumatoid arthritis

The G-1 column is an extracorporeal type granulocytapheresis device packed with 220 g cellulose acetate beads to which granulocytes and monocytes specifically adhere. A total of 59 rheumatoid arthritis patients with elevated granulocyte counts from 4 hospitals in Japan received 2 apheresis sessions of 1 h duration/week for a total of 8 times over a period of 4 weeks. About 55% of the leukocytes which entered the G-1 column were adsorbed onto the beads: 95% were granulocytes, 3.5% monocytes, and 0.4% lymphocytes. Clinical and efficacy assessments showed improvements in swollen joints (p < 0.01), tender joints (p < 0.001), the active joint score (p < 0.001), duration of morning stiffness (p < 0.01), and grip strength (p < 0.001). In good responders, the improvements were observed for up to 12 weeks following the last apheresis. Exacerbation was noted in 2 patients. It is suggested that the efficacy of the G-1 column is attributable to the removal or suppression of hyperactive leukocytes and inflammatory cytokines, inducing a kind of immunomodulation.

A chemiluminescent detection of superoxide radical produced by adherent leucocytes to the subendothelium following thrombolysis: studies with a photochemically induced thrombosis model in the guinea pig femoral artery

Reocclusion following thrombolysis is a major limitation of thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA) because denuded vessel wall exposed to blood following thrombolysis is a favourable surface for platelet and leucocyte deposition. We have applied a chemiluminescence technique to detect superoxide radical (0(-2)) produced by leucocytes adherent to the femoral artery 24 h after photochemically induced thrombogenesis in the guinea pig in vivo and subsequent thrombolysis by rt-PA. Intravenous administration of MCLA, a specific chemiluminescence reagent for detecting O(-2), markedly increased photon emission. the photon emission was markedly potentiated by phorbol myristate acetate and was suppressed by superoxide dismutase. Reocclusion 24 h after rt-PA induced thrombolysis was observed in 10 of 16 animals. Histological observations revealed extensive polymorphonuclear leucocytes adherent to the vessel wall at the site of thrombogenesis and thrombolysis. A higher level of 0(-2) could be detected from the arteries in which thrombolysis was induced compared with those without thrombolysis. Further, the level 0(-2) detected was greater in reoccluded arteries compared with those in which reflow was established. These observations suggest that 0(-2) is produced by adherent leucocytes at the site of thrombolysis and that leucocytes are involved in reocclusion after thrombolysis.

Impairment of phagocytic cell respiratory burst by UVA in the presence of fluoroquinolones: an oxygen-dependent phototoxic damage to cell surface microvilli

Fluoroquinolones are widely used clinically as broad-spectrum antimicrobial agents. One of their side effects is UVA-dependent photosensitivity, observed after the skin is exposed to sunlight. We have investigated five fluoroquinolones and have found that their phototoxicity is oxygen dependent. Human phagocytic leucocytes were stimulated with serum opsonized zymosan to produce superoxide radical (O2-) (respiratory burst) in the presence of a sensitive O2(-)-specific cypridina luciferin analogue, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazol (1,2-alpha) pyrazin-one hydrochloride (MCLA), as chemiluminescence reagent with which O2- can react to induce photon emission. The photon count was used as a measure of respiratory burst activity. When leucocytes were irradiated with UVA for 10 min in the presence of 3 micrograms ml-1 lomefloxacin, ciprofloxacin or norfloxacin, a marked decrease in respiratory burst activity was observed; in this respect, ofloxacin and tosufloxacin were weak. Scanning electron microscopy revealed that the cell surface microvilli were destroyed. The phototoxicity of fluoroquinolones could be abolished if oxygen in the tests was replaced by nitrogen or if the aminothiol DL-cysteine (1.5 mg ml-1) was added prior to irradiation. It is suggested that an oxygen species derived from UVA-excited drug molecules and oxygen mediates the phototoxicity of these fluoroquinolones.

Effect of cystathionine as a scavenger of superoxide generated from human leukocytes or derived from xanthine oxidase in vitro

We studied the direct effects of cystathionine on human leukocyte-generated or xanthine-xanthine oxidase-derived superoxide radicals in vitro. Washed leukocyte suspensions (10(6) cells/ml) prepared from healthy male volunteers were stimulated with phorbol myristate acetate (1 mu M) or opsonized zymosan (1 mg/ml) to generate superoxide radicals, which were measured with a 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo[1,2-alpha] pyrazin-3-one hydrochloride (MCLA)-chemiluminescence method. Cystathionine (30 mu M to 10 mM) significantly reduced superoxide radical-dependent chemiluminescence in the leukocyte system in a concentration-dependent manner. In addition, in the two different methods of determination of superoxide radicals (MCLA chemiluminescence and nitroblue tetrazolium reduction), cystathionine significantly scavenged the superoxide radicals derived from the xanthine-xanthine oxidase system. However, cystathionine did not inhibit the activity of xanthine oxidase during superoxide generation. On the other hand, cystathionine did not show a scavenging effect against hydroxyl radicals derived from Fe2+ -H2O2 on the erythrocyte membrane. These results indicate that cystathionine itself may possess a scavenging function against superoxide radicals rather than against hydroxyl radicals in vitro.

Improvement in rheumatoid arthritis following application of an extracorporeal granulotrap column, G-1

Patients with rheumatoid arthritis (RA) showed significantly (P < 0.01) increased numbers of granulocytes in their peripheral blood compared with normal donors and patients with osteoarthritis, and this finding correlated with interleukin-6 and C-reactive protein levels and active joint score. Then, 17 patients with RA were treated eight times in 4 weeks with a newly developed extracorporeal granulotrap column containing cellulose acetate beads (G-1 column). This column reduced granulocytes in the outflow blood by 50.2% compared with inflow counts. To evaluate the efficacy of G-1 therapy, 17 patients were followed for 12 weeks from the beginning of this therapy. The modified Lansbury index (LI) for monitoring RA activity significantly improved from a pretreatment mean score of 60.8% to a posttreatment score of 51.3%. The lowered scores were maintained up to 12 weeks after the initiation of therapy. Of the four LI items, tender and swollen joint scores showed the most significant improvement, with the tender joint score showing a particularly significant decrease throughout the study period. No serious side-effects were observed. These findings suggested that G-1 therapy was effective for RA.

Direct measurement of superoxide-dependent chemiluminescence from rat skin following UV-dependent fluoroquinolone-induced dermatitis

Fluoroquinolones are widely used for the treatment of bacterial infection. However, some members of the group cause UV-dependent dermatitis. Therefore, animal models are required to screen and predict if a derivative is likely to cause photodermatitis. Under anaesthesia, the hair on the dorsal side of rats was shaved, then a fluoroquinolone derivative, Y-26611 or ofloxacin was administered subcutaneously (SC) followed by irradiation of a 3 cm diameter circular area of the skin with UV-B(ultraviolet-B) for 45 min. Peak photodermatitis was observed 24 h after irradiation in Y-2611-treated skin. Leucocyte infiltration into the skin, mostly polymorphonuclear leucocytes, was verified by histological techniques. O2.- radical generated by activated leucocytes was detected directly from the skin by SC application of a sensitive O2.- -dependent luminescence reagent, MCLA. O2.- -dependent photon emission (chemiluminescence) from the skin was amplified by phorbol myristate acetate and was markedly suppressed by superoxide dismutase. This is the first report of direct detection of chemiluminescence from the skin of a living animal.