Antibody-producing cells in peripheral blood and tonsils after oral treatment of children with bacterial ribosomes

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.

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.

Ribosomal therapy in the treatment of recurrent acute adenoiditis

The aim of this study was to evaluate the efficacy of an oral ribosomal immunotherapy in the management of children with recurrent acute adenoiditis (RAA). 60 children with RAA were included and randomly assigned into two groups (group A and B). Group A children underwent ribosomal prophylaxis, while group B received a placebo. Before, at the end and 6 months after start of the therapy, children underwent medical history, ENT examination, plasma levels of immunoglobulins class E, A, G, M (IgE, IgA, IgG, IgM), tympanometry, active anterior rhinomanometry and VAS scores by children' parents. After the treatment and at the end of the study, in the group A, the serum concentration of IgE was significantly (P < 0.05) lower than in group B (77.34 +/- 6.23 vs. 95.49 +/- 7.07 mg/dl; 74.82 +/- 6.26 vs. 94.44 +/- 7.44 mg/dl), IgA titers were significantly (P < 0.05) higher than in group B (312.04 +/- 18.41 vs. 213.20 +/- 11.82; 309.07 +/- 18.33 vs. 211.73 +/- 11.54 mg/dl) as well as serum concentration of IgG (1401.12 +/- 118.81 vs. 1101.81 +/- 109.64 mg/dl; 1412.19 +/- 116.43 vs. 1144.06 +/- 103.58 mg/dl). At the end of the study, comparison between the two groups showed, in group A: 77% of children (n = 23), versus 23% (n = 7) of group B, with a type A tympanogram; significant (P < 0.05) nasal flow decrease at the rhinomanometric measures; VAS scores were significantly (P < 0.05) improved (1.8 +/- 0.22 vs. 5.1 +/- 0.59) and frequency, severity and social impact of RAA episodes were significantly (P < 0.05) lower than group B. Our results show the therapeutic effectiveness of this approach in the prophylaxis of recurrent acute adenoiditis.

Ribosomal therapy in the prophylaxis of recurrent pharyngotonsillitis in children

OBJECTIVE

Although much has been written on how to manage recurrent pharyngotonsillitis, it remains a controversial topic. The composition of normal commensal oropharynx bacteria may be disrupted by frequently using antimicrobials, by inhibiting sensitive organisms and by allowing resistant organisms to overgrowth. This may cause the recurrence of acute episodes. The aim of this study was to evaluate the efficacy of ribosomal immunotherapy in the prophylaxis of recurrent pharyngotonsillitis.

METHODS

A total of 160 children aged between 5 and 14 years with recurrent pharyngotonsillitis were ramdomized to receive either ribosomal immunotherapy (group A one tablet a day, 8 days a month for 3 months) or a placebo (group B same dosage for the same period).

RESULTS

At the end of the study, each patient treated with Immucytal presented a subjective decrease of symptoms. Compared with group B, group A experienced a significant improvement of some clinical parameters.

CONCLUSIONS

The results show that ribosomal immunotherapy causes a significant improvement of both specific and non-specific immunity and may be effective in the prophylaxis of recurrent pharyngotonsillitis and in preventing recurrences without entailing side effects or bacterial resistance.

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 immunotherapy for recurrent respiratory tract infections in children

Recurrent respiratory tract infections are common in children. They reflect the immaturity of the immune system in its encounter with environmental antigens. Little or no specific protective immune response has yet been established. These infections represent an important public health problem in terms of both treatment (anti-inflammatory or antibacterial drugs for children) and economy. Immunotherapy has been proposed as a means of preventing these recurrent infections by providing children with small doses of inactive bacterial antigens liable to trigger specific and protective immune responses. Among such drugs, ribosomal preparations (to which this review is limited) appear to be not only well tolerated, but also ideally targeted to induce mucosal responses. One preparation of ribosomal mucosal vaccine is commercially available in several countries. Numerous clinical trials in the world have confirmed the positive role of this mucosal ribosomal bacterial vaccine in significantly reducing the number of infections, courses of antibacterials, and absenteeism. In vitro and ex vivo investigations have confirmed that such vaccines indeed trigger protective specific immune responses.

Anti-myelin oligodendrocyte glycoprotein B-cell responses in multiple sclerosis

Humoral auto-immunity to the myelin oligodendrocyte glycoprotein (MOG) is likely involved in the pathogenesis of multiple sclerosis (MS). In 44 MS patients and 30 controls, Ig-producing B cells were identified by their isotype and as MOG-specific spot-forming cells (SFC). Peripheral anti-MOG antibodies were assayed in ELISA as well as anti-butyrophilin antibodies to investigate for molecular mimicry. MS patients had significantly higher levels of IgA- and MOG-SFC than controls, as well as significantly higher antibody responses to MOG and butyrophilin. These data provide added support for the implication of anti-MOG humoral immunity in the pathophysiology of MS, and suggest a balance of systemic (anti-self) and mucosal (environment-modulated) immune reactions in an attempt at regulating the pathogenic specific immune response.

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.

Translocation of ribosomal immunostimulant through an in vitro-reconstituted digestive barrier containing M-like cells

Ribosomal preparations of pathogenic micro-organisms of the upper respiratory tract can be delivered orally for the prevention of recurrent infectious episodes, because they induce mucosal and protective immune responses. The mechanism of mucosal barrier translocation is difficult to study in animal models, little is therefore known about this process. In order to circumvent these problems, we have examined the uptake of ribosomal preparations in three experimental systems that model human intestinal cells. We found that M-like cells displayed a 8.7-fold increase in the uptake of a ribosomal immunostimulant when compared to absorptive or crypt enterocyte-like cells. The product was taken up, translocated, and delivered in the basolateral compartment by cultured M-like cells. No translocation was observed across monolayers of T84 cells (model of crypt cells). Only minimal translocation occured through monolayers of Caco-2 cells (model of absorptive enterocytes). This suggests that, in vivo, colyophilisat is delivered mainly through the M cells overlying lymphoid follicles (Peyer's patches) or nodules of the gut-associated mucosal lymphoid tissue, which are the major inductor sites of mucosal responses. Use of the M-like cell cultured model could be a key step for the development of even more efficient immunostimulators in animals and human.

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).

Inhibition of Streptococcus pneumoniae adhesion by specific salivary IgA after oral immunisation with a ribosomal immunostimulant

Oral 'Ribomunyl' has been shown to increase levels of specific salivary IgA. The ability of specific salivary IgA to inhibit the adhesion of Streptococcus pneumoniae to buccal epithelial cells was investigated in vitro using 13 saliva samples from healthy volunteers who received 'Ribomunyl' therapy for 3 weeks. The S. pneumoniae strain contained in 'Ribomunyl' was [3H]thymidine-labelled and pretreated with dilutions of saliva for 1 hour at 37 degrees C. Bacterial adhesion was measured after 2 hours' contact with human oral epidermal cell monolayers at 37 degrees C under CO2. Nonadherent bacteria were washed off, and the residual radio-activity of the monolayers was compared with that of bacteria not pretreated with saliva. A significant decrease (p < 0.05) in S. pneumoniae adhesion was observed with 6 saliva samples with high levels of specific IgA. This decrease was seen at all dilutions from 1/5 to 1/1000. In contrast, no significant modification of adhesion was seen in the 7 saliva samples with unmodified levels of IgA. These data demonstrate that the increase in salivary IgA levels during 'Ribomunyl' therapy was linked with the capacity of saliva samples to specifically and efficiently inhibit adhesion of S. pneumoniae to buccal epithelial cells in vitro.

Pharmacology of ribosomal immunotherapy

The use of immunostimulating drugs is one way to intervene in the immune system. Many of these agents are of bacterial origin and most are able to stimulate the nonspecific immune response by acting on polymorphonuclear cells (PMNs) and macrophages. Ribosomal immunotherapy ('Ribomunyl') contains both proteoglycans from Klebsiella pneumoniae and ribosomes from 4 different bacterial strains. It can stimulate not only macrophages but also specific antibody production. 'Ribomunyl' has been shown to stimulate many of the functions of PMNs, specifically the formation of oxygenated free radicals, chemotaxis and adhesion. The effect of 'Ribomunyl' immunostimulant on the properties of macrophages is of special interest, as these cells participate in both the nonspecific immune response (phagocytosis, proinflammatory cytokine production) and the specific immune response (antigen processing and presentation, lymphocyte proliferation). 'Ribomunyl' has been shown to increase the production of many cytokines [interleukin (IL)-1, IL-6, IL-8, tumour necrosis factor-alpha and colony-stimulating factor], leading to the activation of the cytokine network. 'Ribomunyl' was also able to stimulate natural killer cells involved in viral immunity. Because of the presence of ribosomes from 4 frequently encountered bacterial strains, 'Ribomunyl' has specific immunostimulant properties. This has been clearly demonstrated in animals and humans, where specific antibody-forming B cells were found in the tonsils after oral administration. However, specific T-cell response has not been reported, suggesting that 'Ribomunyl' could act directly on B cells such as T-cell-independent bacterial antigens.

From Peyer's patches to tonsils. Specific stimulation with ribosomal immunotherapy

Ribosomal immunotherapy has been successfully used since the 1960s to boost the immune system and provide protection against microbial infections. We have investigated both whether and how these immunostimulants behave as natural immunogens in the mucosa-associated immune system. According to current understanding of the physiology of the mucosal immune response, intestinal Peyer's patches and the related solitary nodules are the primary inductive sites involved in the immune protection of all mucosal surfaces. Sensitised lymphocytes generated at these sites reach the general circulation through lymphatic drainage and relocate in mucosal areas by means of specialised 'high endothelial venules'. We hypothesised that orally administered ribosomal preparations would yield sensitised B cells specific for bacterial antigens from the parent strains. These cells should then be detectable in the peripheral blood after ribosomal intake, and identifiable as plasma cells in mucosae-associated tissues after completing their terminal differentiation. Ultimately, specific IgA should appear in secretions. To this end, we studied the immune responses generated in children and adults after 'Ribomunyl' administration, according to various consecutive protocols. The initial hypothesis was confirmed by the identification of specific B cells in the peripheral blood, plasma cells in the tonsillar tissue and specific IgA in the saliva. An animal model involving the use of twin sheep enabled detection of the specific cells in mesenteric and cervical lymph nodes. Analysis of these data indicates that ribosomal preparations trigger the production of lymphocytes specific for both ribosomes themselves and whole bacterial antigens. This supports the fact that small antigenic motifs are carried as partly synthesised peptides on the ribosomal particles. Therefore, ribosomes boost an array of B cells that are specific for many antigenic determinants of the bacteria from which they are extracted. We were also able to show that the stimulation provided was specific, since no response to other bacteria could be detected. Finally, analysis of the kinetics of this stimulation confirmed that oral immunisation generates rapid and transient secretory responses, building increased numbers of memory cells that are readily available to respond to further challenges by either more ribosomal preparations or potential pathogens.

Kinetics of specific salivary IgA responses in man after oral challenge by ribosomal immunostimulant

The kinetics of specific IgA mucosal responses was assessed in 12 healthy volunteers over 3 weeks of treatment by oral administration of an immunostimulant, Ribomunyl, composed of ribosomes from the four bacteria Streptococcus pyogenes, Streptococcus pneumoniae, Klebsiella pneumoniae and Haemophilus influenzae. The levels of IgA specific for these four bacteria increased after each immunization and, after the third week of treatment, were significantly higher than baseline day 0 values. This study demonstrates that oral ribosomal immunostimulation results in the production of specific salivary antibodies liable to recognize whole bacteria antigens, and therefore likely to confer protection. The kinetic analysis performed also demonstrates the rapidity of specific mucosal immune responses after oral stimulation in man, a feature still seldom explored.

Bacterial crude extracts or ribosomes are recognized similarly by peripheral and mucosal B cells

Bacterial ribosomes have been shown to induce effective humoral and cellular immunological responses to whole microorganisms. In this study, the numbers of specific antibody producing cells directed towards Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae ribosomes or whole bacteria sonicates were compared in the peripheral blood and tonsils of 7 children, and in the tonsils, mesenteric and cervical lymph nodes of 10 sheep. No significant difference was noted between the two types of antigens, confirming that ribosomal preparations are able to mimic the immunogenicity of whole bacteria in the mucosae-associated lymphoid tissue.

Compartmentalization of specific B-cells in sheep mucosae associated lymphoid organs

Numerous studies have shown that Peyer's patches (PP) contribute to the seeding of other lymphoid organs in sheep. This was demonstrated by perfusing labeled lymphocytes in PP, and later investigating their presence in drainage lymph nodes, spleen, peripheral blood or bone marrow. These data showed that PP export considerable numbers of cells every day, but provided no information as to their specificity. In this work, we used the enzyme-linked immunosorbent assay (ELISA) spot method to investigate, in the peripheral blood, mesenteric and cervical lymph nodes and tonsils from ten sheep, the numbers of specific B-cells, directed to four common bacteria of the oro-pharyngeal area of mammals: Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae or Klebsiella pneumoniae. The data were obtained from five sets of monozygous sheep, one animal of each pair being previously fed ribosomal preparations of these bacteria. Both prior to and after oral challenge, specific B-cells could be found in all the tissues tested. They were mostly IgG-producing cells and preferentially located in oro-pharyngeal drainage lymph nodes and tonsils. Their numbers increased in these lymph nodes after stimulation, while they decreased in mesenteric lymph nodes. These observations are consistent with the current hypothesis suggesting intestinal sensitization, proliferation and fast emigration of specific B-cells after oral challenge.