Oxidant-scavenging activities of ampicillin and sulbactam and their effects on neutrophil functions

Aging: A Temporal Dimension for Neutrophils

Neutrophils are first-responders, providing early protection against invading pathogens. Recent findings have revealed a temporal dimension to neutrophil function, associated with the clearance cycles for aging neutrophils, and also with a program that endows circulating neutrophils with distinct phenotypic and functional properties at different times of the day, before they are cleared from blood. We review here the process of neutrophil aging and its impact on homeostasis and inflammation. We outline the features of aged neutrophils, examine proposed mechanisms that drive aging, and discuss how these processes may contribute to tissue homeostasis and pathology. In this context we propose that neutrophil aging may optimize host defense by allowing neutrophils to anticipate infections while avoiding permanent activation and subsequent damage.

Protective role of ceftriaxone plus sulbactam with VRP1034 on oxidative stress, hematological and enzymatic parameters in cadmium toxicity induced rat model

We investigated the protective role of ceftriaxone plus sulbactam with VRP1034 (Elores) on hematological, lipid peroxidation, antioxidant enzymatic activities and Cd levels in the blood and tissues of cadmium exposed rats. Twenty-four male rats were divided into three groups of eight rats each. The control group received distilled water whereas group II received CdCl2 (1.5 mg/4 ml/body weight) through gastric gavage for 21 days. Group III received CdCl2 and was treated with ceftriaxone plus sulbactam with VRP1034 for 21 days. The hematological, biochemical, lipid peroxidation levels and enzymatic parameters were measured in plasma and tissues (brain, liver and kidney) of all groups. The Cd, Zn and Fe levels were measured in blood and tissues of all groups. Our findings showed significantly decreased cadmium (p<0.001), malonaldialdehyde (p<0.001) and myloperoxidase (MPO) levels along with significantly increased hemoglobin (p<0.01), RBC (p<0.05), hematocrit (p<0.05) levels and all antioxidant enzymatic activities (SOD, CAT, GR, GPx) in plasma and tissues of ceftriaxone plus sulbactam with VRP1034 treated group as compared to cadmium exposed group. Delta aminolevulinate dehydratase (δ-ALAD) activity was significantly (p<0.001) increased in the blood of ceftriaxone plus sulbactam with VRP1034 treated group as compared with cadmium exposed group. The levels of hepatic and renal parameters were significantly (p<0.001) decreased in ceftriaxone plus sulbactam with VRP1034 treated group as compared to cadmium exposed group. These findings indicate that ceftriaxone plus sulbactam with VRP1034 acts as a potent free radical scavenger and exhibits metal chelating properties that reduce free radical mediated tissue injury and prevent dysfunction of hepatic and renal organs during metal intoxication.

Cytotoxicity towards human endothelial cells, induced by neutrophil myeloperoxidase: protection by ceftazidime

We investigated the effects of the antibiotic ceftazidime (CAZ) on the cytolytic action of the neutrophil myeloperoxidase–hydrogen peroxide–chloride anion system (MPO/H₂O₂/Cl⁻). In this system, myeloperoxidase catalyses the conversion of H₂O₂ and CI⁻ to the cytotoxic agent HOCl. Stimulated neutrophils can release MPO into the extracellular environment and then may cause tissue injury through direct endothelial cells lysis. We showed that human umbilical vein endothelial cells (HUVEC) were capable of taking up active MPO. In presence of H₂O₂ (10⁻⁴ M), this uptake was accompanied by cell lysis. The cytolysis was estimated by the release of ⁵¹Cr from HUVEC and expressed as an index of cytotoxicity (IC). Dose dependent protection was obtained for CAZ concentrations ranging from 10⁻⁵ to 10⁻³ M;this can be attributed to inactivation of HOCl by the drug. This protection is comparable to that obtained with methionine and histidine, both of which are known to neutralize HOCl. This protection by CAZ could also be attributed to inactivation of H₂O₂, but when cytolysis was achieved with H₂O₂ or O₂^- generating enzymatic systems, no protection by CAZ was observed. Moreover, the peroxidation activity of MPO (action on H₂O₂) was not affected by CAZ, while CAZ prevented the chlorination activity of MPO (chlorination of monochlorodimedon). So, we concluded that CAZ acts via HOCl inactivation. These antioxidant properties of CAZ may be clinically useful in pathological situations where excessive activation of neutrophils occurs, such as in sepsis.

Influence of antibiotic therapy on serum levels of reactive oxygen species in ovariectomized bitches

This study was conducted on 60 ovariectomized bitches. The objectives were to measure the mean reactive oxygen species (ROS) concentrations before, during and after surgery, and to investigate the effect of the administration of five different antibiotic treatments: amoxicillin, benzylpenicillin/dihydrostreptomycin, sulfametazine/sulfamerazine/sulfathiazole, enrofloxacin, lincomycin/spectinomycin. The first value recorded represented the mean ROS concentration in anestral bitches and constitutes a reference level with which to compare the subsequent measurements. After premedication, induction of anesthesia and during maintenance and surgery, ROS serum concentrations showed constant values until the end of surgery. After surgery and during antibiotic administration, an increase in ROS concentration occurred, which differed among the five groups in relation to the antibiotics employed. The lowest increases occurred in the groups treated with the combination of lincomycin/spectinomycin, and with amoxicillin; whereas the highest increases were detected in the group treated with enrofloxacin. The three other antibiotics showed an intermediate level of influence on oxidative status.

[Modulatory effect of antimicrobial agents or aminoacids on the oxidative burst of polymorphonuclear neutrophils triggered by formylmethionyl-leucyl-phenylalanine (fMLP)]

We have compared the interplay of several antimicrobial agents and aminoacids on the neutrophil respiratory burst in response to formylmethionyl-leucyl-phenylalanine (fMLP), a chemoattractant. Mainly, an inhibitory effect has been observed in the penicillin family of agents and an enhancing effect in the cephalosporin family of agents. The molecules in which the sulfur numbered 1 in the 6-APA or 7-ACA nucleus was replaced by a carbon or an oxygen, had a different effect as compared with the other members of the family. The modulatory effects of ampicillin and cephalothine were not significant at a concentration lower than 10 mg/l and the effect of cephalothine looked maximum at 20-40 mg/l. If studies in cell-free systems demonstrated that the inhibitory effect of some antimicrobials could be due to a direct oxidant-scavenger activity mainly of HOCl, only hypotheses are proposed to explain the enhancing activity of the others. It could be in relation with (i) a synergistic effect upon fMLP receptor leading to an increase in H(2)O(2)/HOCl production or (ii) the generation of new oxydant products originating in cephalosporin lysis under HOCl attack, which would be able to react with luminol. The interplay of antimicrobial agents with the respiratory burst measured outside the cells probably has no therapeutic consequences because the bactericidal activity of neutrophils is achieved inside phagosomes where few agents are known to come into and where chemical conditions are different. On the opposite, in clinical use, this interplay could be interesting to study for a prevention of side effects.

Oxygen consumption and electron spin resonance studies of free radical production by alveolar cells exposed to anoxia: inhibiting effects of the antibiotic ceftazidime

By EPR spectroscopy, we investigated free radical production by cultured human alveolar cells subjected to anoxia/re-oxygenation (A/R), and tested the effects of ceftazidime, an antibiotic previously demonstrated to possess antioxidant properties. Two A/R models were performed on type II pneumocytes (A549 cell line), either on cells attached to culture dishes (monolayer A/R model; 3.5 h of anoxia, 30 min of re-oxygenation) or after cell detachment (suspension A/R model; 1 h of anoxia, 10 min of re-oxygenation). Ceftazidime and selective inhibitors (SOD, Tiron, L-NMMA) were added before anoxia. Free radical production was assessed by the EPR spin trapping technique. Oxygen consumption was monitored, in parallel with EPR studies, in the suspension A/R model. The production of free radical species was demonstrated by the generation of PBN-radical adducts: (a(N) = 15.2 G) in the monolayer A/R model and a six-line EPR spectrum (a(N) = 15.7 G and a(H) = 2.7 G) in the suspension A/R model. A kinetic study performed by oximetry, in parallel with EPR spectroscopy, demonstrated marked alterations of the cell respiratory function and that the free radical production started during anoxia and increased during re-oxygenation. In the suspension A/R model, the amplitude of EPR spectra were decreased upon the addition of 200 U/ml SOD (37% inhibition), 0.1 mM Tiron (67% inhibition) and 1 mM L-NMMA (43% inhibition). Addition of 1 mM ceftazidime decreased the amplitude of EPR spectra (37% inhibition) in both A/R models. Complementary in vitro EPR studies demonstrated that CAZ scavenged the hydroxyl radical (produced by the Fenton reaction). The protective effect of ceftazidime in the cell model could thus be linked to its ability to scavenge superoxide anions, nitrogen-derived species and hydroxyl radicals.

Interference of antibacterial agents with phagocyte functions: immunomodulation or "immuno-fairy tales"?

Professional phagocytes (polymorphonuclear neutrophils and monocytes/macrophages) are a main component of the immune system. These cells are involved in both host defenses and various pathological settings characterized by excessive inflammation. Accordingly, they are key targets for immunomodulatory drugs, among which antibacterial agents are promising candidates. The basic and historical concepts of immunomodulation will first be briefly reviewed. Phagocyte complexity will then be unravelled (at least in terms of what we know about the origin, subsets, ambivalent roles, functional capacities, and transductional pathways of this cell and how to explore them). The core subject of this review will be the many possible interactions between antibacterial agents and phagocytes, classified according to demonstrated or potential clinical relevance (e.g., neutropenia, intracellular accumulation, and modulation of bacterial virulence). A detailed review of direct in vitro effects will be provided for the various antibacterial drug families, followed by a discussion of the clinical relevance of these effects in two particular settings: immune deficiency and inflammatory diseases. The prophylactic and therapeutic use of immunomodulatory antibiotics will be considered before conclusions are drawn about the emerging (optimistic) vision of future therapeutic prospects to deal with largely unknown new diseases and new pathogens by using new agents, new techniques, and a better understanding of the phagocyte in particular and the immune system in general.

Interference of antibacterial agents with phagocyte functions: immunomodulation or "immuno-fairy tales"?

Professional phagocytes (polymorphonuclear neutrophils and monocytes/macrophages) are a main component of the immune system. These cells are involved in both host defenses and various pathological settings characterized by excessive inflammation. Accordingly, they are key targets for immunomodulatory drugs, among which antibacterial agents are promising candidates. The basic and historical concepts of immunomodulation will first be briefly reviewed. Phagocyte complexity will then be unravelled (at least in terms of what we know about the origin, subsets, ambivalent roles, functional capacities, and transductional pathways of this cell and how to explore them). The core subject of this review will be the many possible interactions between antibacterial agents and phagocytes, classified according to demonstrated or potential clinical relevance (e.g., neutropenia, intracellular accumulation, and modulation of bacterial virulence). A detailed review of direct in vitro effects will be provided for the various antibacterial drug families, followed by a discussion of the clinical relevance of these effects in two particular settings: immune deficiency and inflammatory diseases. The prophylactic and therapeutic use of immunomodulatory antibiotics will be considered before conclusions are drawn about the emerging (optimistic) vision of future therapeutic prospects to deal with largely unknown new diseases and new pathogens by using new agents, new techniques, and a better understanding of the phagocyte in particular and the immune system in general.

Cefoperazone prevents the inactivation of alpha(1)-antitrypsin by activated neutrophils

At sites of neutrophilic inflammation, tissue injury by neutrophil elastase is favored by phagocyte-induced hypochlorous acid-dependent inactivation of the natural elastase inhibitor alpha(1)-antitrypsin. In the present study, cefoperazone prevented alpha(1)-antitrypsin inactivation by neutrophils and reduced the recovery of hypochlorous acid from these cells. Moreover, the antibiotic reduced the free elastase activity in a neutrophil suspension supplemented with alpha(1)-antitrypsin without affecting the cells' ability to release elastase. These data suggest that the drug inactivates hypochlorous acid before its reaction with alpha(1)-antitrypsin, thereby permitting the antiprotease-mediated blockade of released elastase. In conclusion, cefoperazone appears to have the potential for limiting elastase-antielastase imbalances, attenuating the related tissue injury at sites of inflammation.

Effect of cephapirin and mecillinam on the phagocytic and respiratory burst activity of neutrophil leukocytes isolated from bovine blood

Antimicrobial therapy is the most commonly used treatment of bacterial infections in dairy cows. Polymorphonuclear neutrophil leukocytes (PMN) play an important role in the first line defence against invading bacteria and it is important that the function of PMN is not compromised by antibiotics. We investigated the in vitro effect of cephapirin, a first generation cephalosporin, and mecillinam, an amidinopenicillin with activity against mainly Gram-negative bacteria, on phagocytosis and respiratory burst activity of PMN isolated from bovine blood. After in vitro incubation of PMN with different concentrations of the antibiotics, phagocytosis was evaluated by flow cytometry and respiratory burst activity was evaluated by registration of chemiluminescence (CL) with a luminometer. None of the investigated concentrations of cephapirin and mecillinam had an effect in vitro on phagocytosis of Escherichia coli by PMN. At high concentrations (100 and 1000 microg/mL), cephapirin and mecillinam reduced the respiratory burst activity of PMN. Part of these suppressive effects could be ascribed to oxidant scavenging. Inhibitory effects of cephapirin were stronger than mecillinam. In conclusion, cephapirin and mecillinam did not seem to affect antibacterial activity of PMN isolated from bovine blood in vitro at therapeutic concentrations.

Myeloperoxidase autoantibodies distinguish vasculitis mediated by anti-neutrophil cytoplasm antibodies from immune complex disease in MRL/Mp-lpr/lpr mice: a spontaneous model for human microscopic angiitis

Anti-neutrophil cytoplasm antibodies (ANCA) with specificity for myeloperoxidase (MPO) occur in the sera of patients with microscopic angiitis, an autoimmune disease characterized by necrotizing vasculitis and crescentic glomerulonephritis. These autoantibodies have been shown to stimulate neutrophil degranulation and are believed to participate in pathogenesis. A neutrophilic vasculitis has been reported in MRL-lpr mice which has histological appearances similar to microscopic angiitis. In the present study we show that 22% of female MRL-lpr mice develop MPO autoantibodies. These animals develop a clinical syndrome of vasculitis and glomerulonephritis that is distinct from immune complex disease. Anti-MPO monoclonal antibodies derived from these mice are polyreactive and react with double-stranded DNA. They bind a conformational epitope on human MPO which is also expressed by activated human neutrophils. The results suggest that a subset of MRL-lpr mice develop ANCA-related vasculitis rather than systemic lupus erythematosus and may be used as a model for human microscopic angiitis.

Antibacterial agents--phagocytes: new concepts for old in immunomodulation

The possibility that antibacterial agents, primarily directed against microorganisms, also modify host functions is widely recognized. While a knowledge of these non-antimicrobial effects of antibiotics, sometimes considered as 'side-effects', is necessary to prevent antibiotic-associated toxicity, the development of drugs derived from antibacterial agents for use in non-infectious diseases (e.g. motilins and antidiabetic drugs) is a new field of therapeutic research. Interactions between antibacterial drugs and the immune system may contribute to therapeutic efficacy in infectious diseases [1,2]. The immune system itself is a complex pyramid of redundant cellular factors/humoral effectors/mediators, whose fine regulation is just beginning to be unraveled. Phagocytes, ubiquitous and multifaceted cells are key components of cellular immunity, being involved both in immediate defences against non-self targets (pathogens, tumour cells, exogenous molecules, etc.) and in the regulation and triggering of specific immune responses. They are thus, prime targets of immune response modifiers. This review reconsiders the widely explored problem of interactions between antibacterial agents and phagocytes, focusing on future prospects in both infectious and non-infectious diseases.

Antibiotics commonly used to treat mastitis and respiratory burst of bovine polymorphonuclear leukocytes

The in vitro effects of six doses (2 x 10(-3) to 2 x 10(-8) M) of antimicrobial drugs that are frequently used in udder infusions on the capacity of bovine blood polymorphonuclear neutrophilic leukocytes to generate reactive oxygen species were studied by the measurement of luminol-dependent chemiluminescence after stimulation with phorbol 12-myristate 13-acetate. All drugs, except cloxacillin, significantly decreased chemiluminescence at the highest dose. Doxycyline induced the most severe inhibition, followed by neomycin and dihydrostreptomycin. The effect of ampicillin was due to the scavenging of reactive oxygen species and interactions with luminol. The inhibition observed with oleandomycin, neomycin, lincomycin, and dihydrostreptomycin was not due to direct effects on the production of oxidative metabolites but rather to interference with other components involved in the production of light, such as interference with the interaction between luminol and the myeloper-oxidase-H2O2-halide system. The deleterious effects of doxycycline can be explained by several factors: decreased production of superoxide, yellow color, the scavenging of reactive oxygen species, and Ca2+ chelating effect. In conclusion, the results of this study show that antibiotics may affect neutrophil function at concentrations that are reached in the mammary gland after local and repeated administration.

Effect of antibiotics on the phagocytotic and respiratory burst activity of bovine granulocytes

The influence of antibiotics on respiratory burst (phorbol-12-myristate-13-acetate (PMA)-stimulated luminol-enhanced chemiluminescence) and phagocytosis (flow cytometry) by bovine granulocytes was studied in vitro. Phagocytosis was impaired by 1000 micrograms/ml of oxytetracycline, chloramphenicol, erythromycin and spiramycin. All antibiotics, except sulphadiazine, decreased chemiluminescence at 1000 micrograms/ml or lower concentrations. Enrofloxacin increased chemiluminescence. The inhibition by oxytetracycline and danofloxacin was due to absorption of the light emitted by luminol at 425 nm. Oxytetracycline, ceftiofur, spiramycin and erythromycin affected the myeloperoxidase-H2O2-halide system. Ceftiofur, penicillin and danofloxacin showed scavenging effects on H2O2 and OCI. Penicillin and ceftiofur might interfere with luminol. Chloramphenicol, penicillin and ceftiofur affected the production of superoxide radicals. In summary, the observed effects of antibiotics might be of importance during treatment of infectious diseases in normal and immunocompromised animals. However, before classifying a drug as immunosuppressive, attention has to be paid to possible interference with the chemiluminescence assay.

Immunomodulating effects of antibiotics: literature review

Antibiotics can interact directly with the immune system. This is a review of the immunomodulating effects of antibiotics. The Medline database on CD-ROM was searched for the years 1987 to 1994 using the following search string: "thesaurus explode antibiotics/all AND (thesaurus explode immune-system/drug effects OR thesaurus immune-tolerance/drug effects)." Aspects of the immune system studied were aspects of phagocyte functions: phagocytosis and killing, and chemotaxis and aspects of lymphocyte functions: lymphocyte proliferation, cytokine production, antibody production, delayed hypersensitivity and natural killer-cell activity. In order to quantify and to compare immunomodulatory properties of antibiotics we calculated an "immune index," defined as: number of positive statements--number of negative statements/total number of statements. Concerning phagocytosis, positive effects were observed for cefodizime, imipenem, cefoxitin, amphotericin B and clindamycin and negative effects for erythromycin, roxithromycin, cefotaxime, tetracycline, ampicillin and gentamicin. Clindamycin, cefoxition and imipenem induce enhancement of chemotaxis, whereas cefotazime, rifampicin and teicoplanin decrease chemotaxis. Regarding lymphocyte proliferation, cefodizime has the strongest stimulating effect, whereas tetracycline has the strongest negative effect. Except for erythromycin and amphotericin B the number of statements reported is too small to be conclusive for the interpretation of effects on cytokine production. Erythromycin and amphotericin B appear to stimulate cytokine production. As to antibody production, cefodizime has the strongest positive effect, whereas josamycin, rifampicin and tetracycline have marked negative effects. For delayed hypersensitivity and the natural killer-cell activity the number of statements is too small for any single antibiotic to be conclusive. There are three markedly immuno-enhancing antibiotics (imipenem, cefodizime and clindamycin) and eight markedly immuno-depressing antibiotics (erythromycin, roxithromycin, cefotaxime, tetracycline, rifampicin, gentamicin, teicoplanin and ampicillin).

Effect of beta-lactamase inhibitors on normal immune capabilities and their interactions with staphylococcal pathogenicity

The effects of the beta-lactamase inhibitors, clavulanic acid, sulbactam and tazobactam on normal immune responses were investigated. These agents did not interfere with either humoral or cell-mediated immune responses as measured by the hemolytic plaque assay and delayed type hypersensitivity reaction assay respectively. In addition, human polymorphonuclear leukocyte phagocytic activity was not altered by these agents. When these agents were tested for their effect on Staphylococcus aureas adherence to buccal epithelial cells we found that all inhibitors suppressed staphylococcal adherence at therapeutic serum concentrations. Among the inhibitors investigated, sulbactam was found to significantly inhibit the hemolysin production of S. aureus. These data suggest that beta-lactamase inhibitors do not exhibit immunomodulating activity, but they interfere with some of the virulence factors of S. aureus. These findings suggest the advantage of preparations containing these inhibitors.

Treatment of pregnant mice with antibiotics modulates the humoral response of the offspring: role of prenatal and postnatal factors

This study was designed to determine the role of prenatal and postnatal factors underlying altered humoral response of the offspring of mice treated with antibiotics during pregnancy. Pregnant random-bred NMRI mice were administered i.p. from the 11th to 15th day of pregnancy with a mixture of ampicillin and cloxacillin (2:1) in a daily dose of 21 mg/kg body weight. The litters of experimental and control mothers were cross-fostered at birth and the offspring were immunized on the 23rd or 24th postnatal day with SRBC. The primary humoral response was assayed using spectrophotometric determination of SRBC lysis mediated by anti-SRBC IgM antibodies produced by spleen cells. The offspring born of saline-treated mothers and transferred to mothers treated with antibiotics, as well as the offspring born to mothers treated with antibiotics and transferred to mothers treated with saline, produced significantly higher amounts of spleen anti-SRBC IgM than the control offspring. The results suggest that the immune response of the offspring was modulated by both the prenatally and postnatally acting factors, the latter being mediated by effects of antibiotics on the maternal organism.