Pharmacokinetic profile of RU 41740, a bacterial immunomodulator, in mice, rats, and monkeys

The bacterial extract OM-85 BV protects mice against influenza and Salmonella infection

The bacterial extract OM-85 BV has been shown to provide protection against recurrent respiratory infections. We here investigated its efficacy against viral and bacterial infections in murine models. We first evaluated the role of OM-85 BV protecting from an A/PR/8/34 (H1N1) influenza virus infection. In a group treated with 1.75 mg/mouse OM-85 BV all animals survived, compared to 70% in the untreated control group and a group treated with a lower dosage. In addition, the appearance of clinical signs was delayed, their intensity was decreased, and they disappeared faster; also a marked increase in the influenza hemagglutination inhibition antibody level was observed. Since bacterial infections often superimpose viral lung infections, we also investigated on the protection of mice from a Salmonella typhimurium infection after the oral administration of OM-85 BV. Here, 100% of the OM-85 BV treated animals survived compared to 58% of the untreated control group. The mechanism of protection was further investigated: OM-85 BV acts, on the one hand, as an immunogen: the repeated administration of OM-85 BV induced a marked increase in serum antibody levels recognizing pathogenic bacterial strains. On the other hand, the extract acts as a stimulator of the nonspecific macrophage, monocyte, dendritic cell, and granulocyte response. Our findings demonstrate the antimicrobial activity of OM-85 BV against infections, as also has been shown in clinical studies.

The immunomodulating glycoprotein extract from Klebsiella pneumoniae RU 41740 exerts a suppressive effect on human monocyte death by apoptosis

Programmed cell death or apoptosis is a physiological cell suicide process that can be suppressed by survival factors. Monocytes undergo rapid apoptosis in culture, unless signalled by cytokines or the bacterial lipopolysaccharide LPS. We have investigated the effect on monocyte apoptosis of the immunostimulating agent RU 41740 (Biostim), a glycoprotein extract from the Klebsiella pneumoniae K2O1 strain that is used for the prevention of recurrent infections. RU 41740, as LPS, strongly enhanced monocyte survival in vitro, an effect related to apoptosis suppression. RU 41740 at concentration ranging from 1 ng/ml to 10 microg/ml prevented apoptosis induced both by survival factor deprival and by gamma-irradiation. Our observation suggests that enhancement of monocyte survival may represent a component of the reported immunostimulating effect of this compound.

Effect of carboxymethyl-chitin-glucan on cyclophosphamide induced mutagenicity

The effect of high molecular carboxymethyl-chitin-glucan (CMCG), administered either intraperitoneally, intravenously or orally prior to cyclophosphamide injection, on the frequency of micronucleated reticulocytes was evaluated in peripheral blood of female ICR mice. Both intraperitoneal and intravenous administration of CMCG decreased the clastogenic effect of cyclophosphamide. The protective effect of CMCG was concentration dependent, with a higher decrease achieved by 100 mg/kg than by 50 mg/kg body weight. On the other hand, not even five peroral pretreatments with CMCG in the dose of 200 mg/kg body weight during the week prior to simultaneous administration of CMCG and cyclophosphamide induced a decrease of micronucleated reticulocytes in peripheral blood. It is therefore conceivable that CMCG failed to pass through the gastrointestinal tract, probably due to its high molecular weight. The antimutagenic effect of CMCG against cyclophosphamide was manifested by its intraperitoneal and intravenous administration to female ICR mice.

Determination of the antiinfectious activity of RU 41740 (Biostim) as an example of an immunomodulator

Evaluation of the anti-infectious activity of an immunomodulator performed either in vitro or in vivo in animals as in humans must answer three questions: what are the targets? what models should be used to study the mechanism of action? what methodology should be selected for the assessment of therapeutic benefit? In the case of RU 41470 (Biostim), an immunomodulator with a known structure and of biological origin affects immunocompetent cells and two essential mediators: II1 and CSF. Because of multiple interactions between anti-infectious, anti-inflammatory and anti-allergic responses, as well as the pleiotropism of mediators, there exists no absolute predictive index of activity in vivo and, independently of models of immune deficiency, experimental infections are a particularly useful pharmacological model for study of the anti-infectious activity of any immunomodulator. In this model, RU 41470 tested by oral, intraperitoneal and aerosol administration, proved to be active regardless of the type of infectious agent for extracellular bacteria, intracellular bacteria, viruses or yeasts. Because of special local features of anti-infectious defences (pulmonary, cutaneous), the target organ must be identified when studying mechanism of action. RU 41740 stimulates the metabolic activities of alveolar macrophage and the target organ is the respiratory tract. From a clinical pharmacology standpoint, stimulation of different immune components has been investigated with RU 41470 at different dosages, using double-blind versus placebo designs. Target pathology, regardless of severity, includes a risk of infection and the existence of an immunological deficiency. Chronic bronchitis is a reference pathology since patients are subject to episodes of infection, resulting in acute decompensation and contributing to worsening of the ventilatory obstructive disorder. Clinical efficacy in terms of anti-infectious prophylaxis must be evaluated by a strict methodological approach: randomized double-blind placebo-controlled trials with prolonged follow-up. RU 41470 is effective in prophylaxis of respiratory infections in chronic bronchitis (reduction in the number of respiratory infections, their duration and in antibiotic consumption) and in prophylaxis of respiratory tract infections in children over one year old. Clinicians faced with the perplexity of the mechanism of action of immunomodulators and their number are preoccupied above all by the response which such an anti-infectious immunomodulator can offer in a context of clinical reality.(ABSTRACT TRUNCATED AT 400 WORDS)