Effect of an in vivo immunostimulant treatment on PMN functions: interaction with antibiotics in vitro

Role of ribomunyl((r)) in the prevention of recurrent respiratory tract infections in adults : overview of clinical results

Recurrent respiratory tract infections (RRTIs) in adults are the result of an imbalance between lung defense mechanisms, and bacterial burden. Antibacterial treatments can temporarily restore the equilibrium between host and bacterial load, but do not prevent recurrence of infection. An alternative approach to prevent recurrence of infection is treatment with an immunostimulant, which provides immune protection against repeated bacterial and viral infection. All immunostimulant products are bacterial in origin: lysates (first generation immunostimulants), or bacterial extracts, like bacterial ribosomes, or membrane proteoglycans. This review highlights the current state of knowledge regarding the use of immunostimulants in adults with RRTIs, taking the ribosomal immunostimulant Ribomunyl((R)) as an example. Many studies are available on the mechanism of action and clinical efficacy in prevention of RRTIs in adults treated with Ribomunyl((R)). The effect of this immunostimulant on anti-infectious responses is explained by a stimulation of both nonspecific (innate) and specific (adaptive) immunity. In order to obtain a global overview of the therapeutic efficacy of Ribomunyl((R)) the most pertinent trials were selected from the literature based on adequate patient numbers and good methodology. Results of double-blind placebo-controlled trials using Ribomunyl((R)) for the treatment of different upper or lower RRTIs have demonstrated a statistically significant reduction in the number of infectious episodes and as a consequence, a decrease in antibacterial consumption, after 3 and 6 months of treatment. The tolerance profile of Ribomunyl((R)) was good in all studies. Economic evaluations suggest that savings can be made in healthcare expenditure, in patients with recurrent episodes of infection. It is concluded that Ribomunyl((R)) is effective in preventing and reducing upper and lower respiratory tract infections in adults. The product may also have an impact on reducing the development of bacterial resistance, as a result of fewer courses of antibacterials required to treat patients with RRTIs.

The increased expression of CD11c and CD103 molecules in the neutrophils of the peripheral blood treated with a formula of bacterial ribosomes and proteoglycans of Klebsiella pneumoniae

AIM

To evaluate the effect of a preparation with bacterial ribosomes and proteoglycans from Klebsiella pneumoniae «R» on the in vitro expression of CD11c and CD103 molecules in neutrophils from peripheral blood.

METHODS

Isolation of neutrophils from peripheral blood with Ficoll-Paque, incubation with R and detection of CD11c and CD103 through flow cytometry.

RESULTS

Six hours after the incubation period, CD11c expression increased significantly compared with the control with 125 and 500μg/ml of R (P=.017 and P=.006, respectively). CD103 expression induced with 125μg/ml of R after 6hours was significantly higher than that observed after 4hours at the same concentration (P=.014) and that found with 62.5μg/ml (P=.017) of R.

CONCLUSIONS

The increased expression of CD11c and CD103 induced by R in the neutrophils could contribute to the R mechanism against respiratory pathogens.

Meta-analysis of published clinical trials of a ribosomal vaccine (ribomunyl) in prevention of respiratory infections

OBJECTIVE

To perform a meta-analysis using data from all clinical trials and studies of a ribosomal vaccine (Ribomunyl((R))) in order to estimate its overall effect on the number of infections and antibacterial courses used per person.

DESIGN AND SETTING

Meta-analysis of studies performed between 1985 and 1999 in 7 European countries and also in Kazakhstan, Tunisia, Morocco and Argentina.

PATIENTS AND PARTICIPANTS

Information from 14 213 adults and children.

RESULTS

There were 9 randomised, double-blind, placebo-controlled studies, 3 randomised nonblind studies and 16 nonblind studies with no placebo arm in which the response to ribosomal vaccine was compared with historical information. The mean number of infections per person in a study period of 3 months using placebo was found to be 2.39 (standard error +/- 0.50), and in a study period of 6 months was 3.35 (+/-0.41) infections. In both study periods, ribosomal vaccine use was associated with a reduction in the number of infections per person of 1.43 (+/-0.26). In the study period, patients on placebo reported 3.02 (+/-0.44) antibacterial courses, whereas ribosomal vaccine was associated with a reduction of 1.32 (+/-0.42) antibacterial courses.

CONCLUSIONS

In spite of variability in data quality, and the small sample size in some of the studies, we conclude that in patients with recurrent respiratory infections ribosomal vaccine significantly reduces both the number of infections and the number of antibacterial courses compared with placebo. This study is a strong and objective demonstration of the efficacy of ribosomal vaccine in limiting the number of otorhinolaryngological infections in children and adults.

Prevention of recurrent respiratory tract infections in children using a ribosomal immunotherapeutic agent: a clinical review

Recurrent respiratory tract infections (RRTIs) in children constitute a serious problem worldwide. Some children experience considerable morbidity as a result of RRTIs and receive repeated courses of antibacterials that are not effective against viral infectious agents and can increase bacterial resistance. Furthermore, the direct and indirect costs of RRTIs to the community are substantial. In this article, we review the available clinical evidence relating to use of the bacterial immunostimulant Ribomunyl for the prevention of RRTIs in children. The product is composed of ribosomal fractions from four bacteria involved in RRTIs as well as a membrane fraction from one of these bacteria (Klebsiella pneumoniae). Ribomunyl stimulates production of specific humoral and secretory antibodies against the four bacterial strains included in the compound. The product also stimulates non-specific immunity. Thus, Ribomunyl stimulates both the innate and acquired immune systems and offers preventive efficacy against both bacterial and viral infections. To perform this review, we searched the MEDLINE database for articles on Ribomunyl and then included only those publications that described placebo-controlled studies, complied with Good Clinical Practice standards, used the product in official registered indications, and administered it at the recommended dosages. In this way, we were able to generate a comprehensive profile of use of the product and draw valid conclusions about its clinical role. In clinical trials of children, Ribomunyl reduced the number of upper or lower RRTIs, the primary outcome measures. Other favorable results relating to efficacy parameters that served as secondary outcome measures in these studies included a reduction in antibacterial treatments, shorter duration of recurrent episodes, reduced need for other medications such as expectorants, smaller number of lost school days or parent absenteeism from work, less fever, and reduced hearing loss. Studies focusing on particular conditions, such as otitis media, or those that included specific patient groups, such as very young children, reported similar findings. Adverse events occurred very rarely and were mild. Their frequency was similar to that reported in placebo groups, and consisted mostly of fever, otorhinolaryngologic symptoms, and cutaneous events. In conclusion, this review clearly demonstrated that Ribomunyl is effective in preventing upper and lower RRTIs in children. Ribomunyl provided a reduction in the number, duration, and severity of infectious episodes and, thereby, reduced antibacterial use and the likelihood of consequent development of bacterial resistance. Ribomunyl also decreased absence from work or school, which has important economic consequences.

Immunostimulants revisited: focus on the pharmacology of Ribomunyl

Ribomunyl is an immunostimulant that was developed and commercialized in the 1980s in France and has subsequently been made available in a large number of countries. The formulation is composed of proteoglycans from Klebsiella pneumoniae and of ribosomes from four of the most commonly encountered bacterial strains in recurrent respiratory tract infections. While it is obviously difficult to present a thorough summary of all historical data, here we revisit the mode of action of this immunostimulant and present a perspective in the context of the most recent data and hypotheses on the mechanisms of the antibacterial immune responses. We provide various examples of these mechanisms in innate immunity (phagocytosis, cell adhesion, dendritic cell maturation, Toll-like receptors, interferon production, proinflammatory cytokines, activation of natural killer cells), as well as in adaptative immunity (polyclonal activation of T and B cells, specific immunoglobulin A immune response in an integrated view of the mucosal immune system, and T helper type 1/type 2 [Th1/Th2] regulation and balance). The effect of this immunostimulant on anti-infectious responses can be explained, not only by a stimulation of the antibacterial defense directly assumed by innate immunity, but also by a stimulation of the specific (adaptative) immune response related to the activation of dendritic cells, of which the pivotal role in T-cell differentiation is already well known. This supports the potential of bacterial immunostimulants such as Ribomunyl in anti-infective therapy.

Ribosomal immunostimulation: assessment of studies evaluating its clinical relevance in the prevention of upper and lower respiratory tract infections in children and adults

OBJECTIVE

To review the efficacy of the ribosomal immunostimulant Ribomunyl in preventing upper and lower respiratory tract infections.

DESIGN AND SETTING

Review of studies of 3 and 6 months' duration comprising part of the international registration file.

PATIENTS

Data from 2117 patients (1215 children and 902 adults); ribosomal immunostimulant n = 1062, placebo n = 1055.

RESULTS

Nineteen randomised, double-blind, placebo-controlled clinical trials were performed between 1983 and 1994 in Europe. In children with ear-nose-throat (ENT) infections, 3 months' ribosomal immunostimulant treatment significantly decreased the mean number of recurrences (27-68% reduction), and reduced the duration of infection (28-66% reduction) and antibacterial requirement (29-60% reduction). Ribosomal immunostimulant was similarly effective in children with ENT and bronchopulmonary infections, reducing the mean number of recurrences by 32-61% compared with placebo. In children with otitis media, ribosomal immunostimulant reduced recurrences by 10-53% and also reduced the duration of infection, antibacterial use and local surgery requirement. Results obtained from studies of 6 months' duration confirmed or extended these results. In adult patients with ENT or mixed respiratory infections, ribosomal immunostimulant produced similar reductions to those seen in children for recurrent infections (54-78% reduction), duration of infection (42-79% reduction) and antibacterial use (38% reduction).

CONCLUSIONS

These results clearly demonstrate that ribosomal immunostimulant is effective in preventing and in reducing upper and lower respiratory tract infections in children and adults.

A preventive measure for otitis media in children with upper respiratory tract infections

Recurrent upper respiratory tract infections (URTI) are very common in patients of all ages. Rhinitis, bronchitis, chronic sinusitis and otitis appear to be the prevalent forms of recurrent respiratory infections in the paediatric population. The aim of treatment is so the solution of the respiratory pathology and the also the prevention of their complications. Antibacterial therapy is still the classical treatment approach in patients both with respiratory tract infections and with otitis media, despite the fact that antibacterials have several well known drawbacks, especially when used to treat recurrent infections. Eighty-four paediatric patients of both sexes (range: 4-14 years) with otitis were enrolled in the study. Patients were included if they had a >2 years' history of recurrent or chronic respiratory infections, and/or had experienced at least three episodes requiring medical consultations and/or treatment during the winter prior to the study. The young patients were randomised to receive Immucytal (group A) or placebo (group B) treatment according to the following protocol: (1) starting therapy (1 month): one tablet daily in the morning 4 days per week for 3 consecutive weeks; (2) maintenance period (5 months): one tablet daily in the morning 4 days per week for 1 week every month. Placebo and Immucytal tablets were identical in shape and size, in order to maintain double-blind conditions. Patients of group A with recurrent URTI had a significantly decreased incidence of ENT infections, fever and shorter duration of illness, decreased requirement for ancillary medications and fewer work-days lost. The reduction in the incidence of infectious episodes became significant vs. placebo. A significantly improved outcome vs. placebo was also observed on the incidence of fever, frequency and duration of infectious episodes, ancillary therapies. Immucytal treatment was associated with significant changes in both immunological and auditory function parameters. Serum concentrations of immunoglobulins were significantly increased in Immucytal. For both evaluations, a significant difference between treatment groups was found (P>0.001). Preventive strategies, such as ribosomal immunotherapy, may represent a valid alternative approach.

Amoxycillin/clavulanic acid combinations increase transmigration of leucocytes through endothelial cell monolayers: endothelial cells play a key role

Postoperative inflammation is still viewed as an unresolved problem. During inflammation, leucocytes play a tremendous role and migrate from intravascular spaces into the tissue to attack microorganisms. Different agents, e.g. anaesthetic drugs, are able to influence leucocyte recruitment. Previous studies have investigated the influence of amoxycillin on chemotaxis of leucocytes alone. The aim of our study was to examine the effect of amoxycillin/clavulanic acid (co-amoxiclav) on leucocyte migration through endothelial cell monolayers (ECMs). Human umbilical endothelial cells were cultured on microporous membranes, achieving a monolayer. Polymorphonuclear neutrophil leucocytes (PMNLs) were used in a migration assay. The numbers of untreated PMNLs migrating through untreated ECMs were used as control and set as 100%. PMNLs and/or ECMs were pretreated with co-amoxiclav using clinically relevant as well as higher and lower concentrations. Co-amoxiclav was able to increase PMNL migration through ECMs significantly (P<0.05) when both cell types were treated (291+/-18.7%). When PMNLs or ECMs were treated alone, it could be shown that ECMs were more affected than PMNLs. The greatest effect was shown when both cell types, PMNLs and ECMs, were treated. In conclusion, co-amoxiclav was identified as a potent drug to increase leucocyte transmigration through ECMs. ECMs were also critically involved. Co-amoxiclav also affects endothelial cells.

Effectiveness of ribosomal fractions of Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and the membrane fraction of Kp (Ribomunyl) in the prevention of clinical recurrences of infectious rhinitis. Results of a multicenter double-blind placebo-controlled study

A multicenter, double-blind, placebo-controlled study was conducted to investigate the efficacy of an immunostimulant, Ribomunyl, in the prevention of recurrences of infectious rhinitis in adults. This trial involved 327 patients (168 Ribomunyl treated and 159 placebo cases) with an average of 4.3 +/- 1.8 rhinitis episodes per patient recorded during the year preceding the study. The main criterion of efficacy was the cumulative number of recurrences of infectious rhinitis during a 6-month follow-up period, as analyzed by standard tests. An additional analysis of relative risk of recurrences used multivariate failure for time data. Ribomunyl was effective throughout the study period, starting from the first month of treatment: a mean of 1.0 +/- 1.1 recurrences was recorded in the Ribomunyl group as compared to 1.5 +/- 1.4 recurrences in the placebo group; this indicated one-third fewer infections (P = 0.001). The protective effect of Ribomunyl on the relative risk for recurrences was estimated to be 0.58 by multivariate analysis (95% CI: 0.43-0.78, P = 0.0001). Analysis of secondary criteria also favored Ribomunyl: 38.5% less antibiotic courses per patient (0.8 +/- 1.3 vs 1.3 +/- 1.6; P = 0.002) and the number of days with antibiotics (5.6 +/- 9.3 vs 9.1 +/- 12.1; P = 0.002).

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).

Reduced anti-Pseudomonas aeruginosa activity of a cephalosporin, cefodizime, in rats whose neutrophils were selectively depleted by a monoclonal antibody

In order to clarify the mechanisms of the in vivo antibacterial activity of a cephalosporin, cefodizime (CDZM), the effect of this antibiotic on Pseudomonas aeruginosa E7 infection was examined in rats whose neutrophils had been selectively depleted by monoclonal antibody RP-3. CDZM was less effective in RP-3-treated rats than in untreated rats. However, treatment of rats with recombinant human granulocyte-colony stimulating factor (rhG-CSF) augmented the in vivo activity of this antibiotic. Furthermore, the in vivo antibacterial activity of two other cephalosporins, cefpimizole (CPIZ) and cefoperazone (CPZ), was bilaterally affected by a rise or fall in the neutrophil number, although to a lesser degree than was the case with CDZM. Taken together, neutrophils play an important role in the in vivo antibacterial activity of certain cephalosporins.

The long-term antimicrobial prophylaxis of chronic bronchitis exacerbations

Infectious exacerbations are the major cause of mortality in patients with chronic bronchitis, particularly in elderly subjects. Considering that the preventive use of antibiotics has provided no clear-cut evidence of real efficacy, it has become quite common to use treatments potentially able to stimulate the immune system for prevention of exacerbations of chronic bronchitis. This treatment, based on the oral administration of bacterial extracts, should, at least in theory, stimulate the immune defenses and reduce the incidence of recurring respiratory tract infections. Although during the last few years a good effort to define better the real efficacy and role played by bacterial extracts in chronic bronchitis has been made, their clinical effectiveness is still the subject of debate and the results of some clinical trials are controversial. Particularly, its mechanism of action remains poorly understood, although a huge effort has been made in this direction.

In vitro stimulation of polymorphonuclear cell adhesion by ribomunyl and antibiotic + ribomunyl combinations: effects on CD18, CD35 and CD16 expression

Several functions of polymorphonuclear cells (PMNs) require adhesion to occur. Various membrane proteins' functions such as CD18 (beta 2 chain of integrin), CD35 (CR1) and CD16 (F c gamma Receptor III) participate in adhesion. In vivo treatment with Ribomunyl (R), an immunomodulating agent, was shown to enhance adhesion and migration of PMNs. To explore the direct effect of R on PMNs, cells from healthy subjects were treated in vitro with R. A significant increase of PMN adhesion and expression of CD18 and CD35 molecules were observed with 50 and 100 micrograms/ml of R after 2 h incubation. However, R-treatment decreased the PMN reactivity towards anti-CD16 (F c gamma RIII) monoclonal antibody. The effect of R on adhesion and membrane molecule expression was independent of the presence of serum and of polymixin B. Thus, this effect cannot be due to lipopolysaccharide (LPS) contaminants and does not require interactions with serum components. In previous studies, it was shown that in vitro amoxicillin increased some PMN functions whereas josamycin decreased them. The in vitro incubation of PMNs with R and amoxicillin (100 micrograms/ml) potentiated the positive effect of amoxicillin on adhesion and the antibiotic counterbalanced the negative effect of R on CD16 expression. In addition, R compensated the negative effect of josamycin (100 micrograms/ml) on PMN adhesion and on CD18 and CD35 expression. This study indicates: (1) the direct effect of R on PMN adhesion and on expression of molecules involved in adhesive-mediated functions, and (2) the beneficial effect of the association of R with antibiotics which can stimulate PMN activity.

The Use of the Vitality and Chemotaxis of Human Polymorphonuclear Leukocytes for the In Vitro Estimation of the Acute Toxicity of the First Ten Chemicals from the MEIC List

The acute cytotoxicity of the first ten MEIC chemicals has been estimated by others in various cell lines. In the present investigation, isolated human polymorphonuclear leukocytes (PMN) from ten healthy non-smoking laboratory personnel were used to assess in vitro toxicity of the same chemicals.

The cells were treated with different concentrations of the respective chemicals for three hours and their vitality and chemotaxis were tested. Vitality was measured by fluorescence microscopy after the addition of fluorescein diacetate and ethidium bromide. Living cells which took up and hydrolysed fluorescein diacetate, and dead cells, stained by ethidium bromide, were counted and the percentage of live cells was calculated.

Locomotion stimulated by the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (F-MLP), was measured in blind-well Boyden chambers and a chemotactic index was calculated.

The results were mathematically transformed to produce a linear curve, and then fitted by the linear least squares procedure, from which LC50 and IC50 values were obtained by interpolation. All the chemicals decreased the vitality and inhibited the chemotaxis of the PMN. Obviously the chemotactic test was more sensitive than the vitality one. A correlation (r = 0.933) was found between vitality and chemotaxis inhibition. Spearman rank correlation analysis revealed significant correlations between our results and those from in vitro experiments conducted in other laboratories, as well as with data concerning mouse, rat and human lethal doses.