Digestive tract microflora liberates low molecular weight peptides with immunotriggering activity

Probiotics for prevention of nosocomial infections: efficacy and adverse effects

PURPOSE OF REVIEW

In this era of increasing antimicrobial resistance, use of probiotics in infection prevention has brought new perspective. However, in 2008 the, until then considered, safe use of probiotics became an important topic after publication of a trial showing excess mortality in patients on probiotic prophylaxis. In this article, we review the concept of infection prevention by probiotics and the present knowledge of the efficacy of probiotics in prevention of infections among patients with abdominal diseases and in intensive care. Safety issues of probiotics will be discussed extensively.

RECENT FINDINGS

Over 30 clinical trials with probiotics to prevent infections have been published, some of which were prematurely stopped recently. Studies with critically ill patients and patients with abdominal diseases showed conflicting results regarding the effects of probiotics on infection rates, as did meta-analyses. These studies are difficult to compare because different probiotics were used which all have different efficacy and safety profiles.

SUMMARY

The efficacy of probiotics in infection prevention among critically ill patients is still not unequivocally determined. The safety profile differs per probiotic strain and should not be generalized towards other strains and patient populations. A well designed and well powered clinical trial with clear endpoints to demonstrate efficacy is warranted.

[Immune modulation with Kanne-Brottrunk to prevent pollinosis: a 1-year observational study with follow-up]

BACKGROUND

The immune enhancing properties of probiotics are scientifically well documented. Whether Kanne- Brottrunk (Selm-Bork, Germany) may play a preventive role in Pollinosis, was investigated in this study for the first time.

PARTICIPANTS AND METHODS

30 volunteers with pollinosis and a mean disease duration of 20 years agreed to consume 0.7 l Kanne-Brottrunk daily for one year. At the beginning and at the end of the study and one year later they retrospectively rated their pollinosis related quality of life during the previous pollinosis season with a disease specific questionnaire (FLQA: Freiburg Life Quality Assessment). Additionally, the change was rated directly and status was assessed in November 2002, January 2003, May 2003 and November 2003.

RESULTS

24 volunteers finished the study, although some of them consumed less than 0.7 l daily. 17 out of 20 assessed participants (85%) rated their pollinosis in the treatment year as 'very much better' or 'much better' (57% in the follow-up year). In 2003, the FLQA showed clinically relevant effect sizes (0.85-2.29) and statistically significant improvements (p < 0.05) for all six scales. In 2004, the improvements were slightly less pronounced (effect sizes 0.89-1.53) and were statistically significant for 4 scales (p < 0.05). 12 patients reported a relevant reduction or cessation of medication and many reported improvements of other immune related conditions.

CONCLUSIONS

The observed improvements under regular daily consumption of Kanne-Brottrunk were marked and statistically significant. A randomized controlled trial would be necessary to allow causal conclusions.

Probiotics: a practical review of their role in specific clinical scenarios

The use of probiotics (live viable microbial organisms) in the treatment of specific diseases has evolved into an extremely valuable option yet to be optimally used in clinical medicine. Probiotics have been shown to have immunomodulating properties and enhance the mucosal barrier. This review will briefly discuss the use of probiotics in inflammatory bowel disease, pancreatitis, liver transplantation, and various uses in diarrhea. When using probiotics, one must be cautious of the sometime overzealous claims that are commonly made when dealing with medical foods. As we begin to appreciate the degree of complexity that our indigenous microbial population has on health, it is only then that we can begin to understand the importance in disease. In the arena of probiotics, numerous fundamental questions remain unanswered.

Bio-ecological control of acute pancreatitis: the role of enteral nutrition, pro and synbiotics

PURPOSE OF REVIEW

Increasing knowledge, both experimental and clinical, supports the fact that early and aggressive enteral nutrition has the capacity to reduce superinflammation and prevent infections in severe acute pancreatitis. Clearly, the main role of enteral nutrition is to boost the immune system, and not, at least initially, to provide calories. Whereas enteral nutrition improves, parenteral nutrition reduces immune functions.

RECENT FINDINGS

The content of enteral nutrition solutions is more important than the route of administration per se. Antioxidants, plant fibres and live lactic acid bacteria are especially important for boosting the immune system. Recent studies support the fact that enteral nutrition and the supply of fibres and live lactic acid bacteria may significantly reduce the rate of infections. So far none of the treatments has been able to reduce the incidence of the systemic inflammatory response syndrome and multiorgan dysfunction syndrome. A recent unpublished study indicates, however, that the systemic inflammatory response syndrome and multiorgan dysfunction syndrome can also be reduced if much higher doses of lactic acid bacteria and a combination of several bioactive lactic acid bacteria are used (synbiotics).

SUMMARY

Immunosupporting enteral nutrition with synbiotics is an important tool to control superinflammation and infection, and might also reduce the multiorgan dysfunction syndrome and systemic inflammatory response syndrome. It is essential that it is supplied early, if possible in the emergency room. New autopositioning regurgitation-resistant feeding tubes are available to facilitate such a policy.

Bio-ecological control of perioperative and ITU morbidity

BACKGROUND

Perioperative and intensive therapy unit (ITU) morbidity and mortality has remained unchanged during the past several decades, and this at an unacceptably high level. It is most likely, in the EU countries annually, that more than 1 million people suffer severe sepsis and some 300,000 die. Pharmaceutical attempts at prevention and treatment have, despite extensive efforts, hitherto failed to improve outcome more significantly. Much supports the fact that sepsis and its severe consequences are results of a malfunctioning innate immune system, impaired by both lifestyle and disease. A series of mostly simple measures to prevent further deterioration of the immune system, and to boost it, is recommended. Among the measures recommended are some modifications of surgical and postoperative management: restricted use of antibiotics, attempts made to maintain salivation and GI secretions, omission of prophylactic gastric decompression, postoperative drainage and preoperative bowel preparation, restricted use of stored blood, avoidance of overload with nutrients, uninterrupted enteral nutrition but also tight blood glucose control, supply of antioxidants, administration of prebiotic fibre and probiotic lactic acid bacteria. Nutritional control of postoperative morbidity includes use of so-called synbiotics, e.g. a combination of bioactive lactic acid bacteria (LAB) and bioactive plant fibres.

RESULTS

Dramatic reduction in (in reality, almost abolishment of) septic morbidity is reported following supplementation of specific bioactive lactic bacteria in combination with prebiotic plant fibres, as tried in controlled studies in connection with extensive abdominal operations, liver transplantation and severe acute pancreatitis.

Gut microbial ecology in critical illness: is there a role for prebiotics, probiotics, and synbiotics?

Approximately 70% of the immune system is localized in the gastrointestinal tract: its glands, mucosa, and mucosa-associated lymphoid system. The system influences health conditions because it produces large amounts of important gastrointestinal secretions as rich as breast milk in health-supporting and disease-preventing factors, and because of its rich gastrointestinal flora. The intestine normally contains 10 times more microbes than there are eukaryotic cells in the entire body. The optimal function of these microbes depends on the supply of food destined for the colonic bacteria (fermentable fibers, complex proteins, gastrointestinal secretions). The consideration of these functions influences outcome. Unfortunately, the conditions (supply of drugs-especially antibiotics, and reduced supply of food-especially fruits and vegetables) in the modern ICU are extremely poor both for optimal gastrointestinal secretion and for flora and need more attention. To improve treatment, a supply of new and effective flora (probiotics) and food for the flora (prebiotics) is needed, from which numerous health-supporting products (synbiotics) will be produced and absorbed at the level of the mucosa, mainly in the lower gastrointestinal tract.

Pre-, pro- and synbiotics

Approximately 70% of the immune system is localized in the gastrointestinal tract. The saliva and gastrointestinal secretions, as well as flora (probiotics) and supplied fibres (prebiotics), are important for optimal function. Probiotic bacteria have been shown to influence the immune system through several molecular mechanisms. Pre-, pro- and synbiotics (products produced by fermentation) offer both protection against and cure of a variety of endemic and acute diseases. This review summarizes the present experience in various forms of diarrhoea, inflammatory bowel disease, and Helicobacter infections, in intensive care patients and in connection with extensive surgery.

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.

Importance of intestinal colonisation in the maturation of humoral immunity in early infancy: a prospective follow up study of healthy infants aged 0-6 months

AIM

To evaluate the role of intestinal microflora and early formula feeding in the maturation of humoral immunity in healthy newborn infants.

STUDY DESIGN

Sixty four healthy infants were studied. Faecal colonisation with Bacteroides fragilis group, Bifidobacterium-like, and Lactobacillus-like bacteria was examined at 1, 2, and 6 months of age, and also the number of IgA-secreting, IgM-secreting, and IgG-secreting cells (detected by ELISPOT) at 0, 2, and 6 months of age.

RESULTS

Intestinal colonisation with bacteria from the B fragilis group was more closely associated with maturation of IgA-secreting and IgM-secreting cells than colonisation with the other bacterial genera studied or diet. Infants colonised with B fragilis at 1 month of age had more IgA-secreting and IgM-secreting cells/10(6) mononuclear cells at 2 months of age (geometric mean (95% confidence interval) 1393 (962 to 2018) and 754 (427 to 1332) respectively) than infants not colonised (1015 (826 to 1247) and 394 (304 to 511) respectively); p = 0.04 and p = 0.009 respectively.

CONCLUSIONS

The type of bacteria colonising the intestine of newborns and the timing may determine the immunomodulation of the naive immune system.

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.

Microflora-associated defense stimulating factors

Mucosal surfaces are habitats for the physiological microflora and are closely related to the mucosal immune compartment (mucosa-associated lymphoid tissue, MALT). Recently, considerable evidence has accumulated showing that various members of the physiological microflora liberate low molecular weight substances which, apparently, are essential for the adequate immune response of the host. Antibiotic decontamination (e.g. of the BALB/c mouse gastrointestinal tract) results in a lack of generation of immunopriming microbial substances leading to immunosuppression. Biochemical analysis of the microbial substances revealed reproducible chromatographic fractions which selectively influence maturation, proliferation and activation of mononuclear immune cells.

Problems and priorities for controlling opportunistic pathogens with new antimicrobial strategies; an overview of current literature

An International Study Group on New Antimicrobial Strategies (ISGNAS) has been formed in response to the recognition that development of microbial resistance to antibiotics is becoming a serious, world-wide problem. The group met in 1993 for the first time to discuss the feasibility of developing rational alternatives to the use of antibiotics and prepared, as a result, a comprehensive overview of normal (physiological) mechanisms involved in the control of potentially pathogenic (oppotunistic) microorganisms. One objective of ISGNAS is to understand the conditions which allow opportunistic microbes present among the symbionts to cause an infection. There is a need for more coherent information concerning the habitat, growth requirements and host and pathogen properties which allow opportunistic pathogens to cause life-threatening infections. In particular, information is urgently being sought to understand the complexity of the interactions between the vast number of microbial species, and the interactions between the microbes and their host. Another goal is to inspire and enable basic and clinical research that will lead to the development of new therapies for regulating colonization, translocation and infection by opportunistic micro-organisms in patients during periods of decreased resistance. With a sufficient amount of knowledge of how healthy individuals keep opportunistic micro-organisms under control, it may become feasible for physicians to maintain host resistance and inter-microbial factors involved in the containment of opportunistic microbes. Therapies aimed at boostering natural resistance mechanisms will be of critical importance to individuals whose resistance has been compromised as a result of another clinical condition.

Propionibacterium acnes-metabolites inhibit experimental lung metastasis of murine sarcoma L-1 in BALB/c-mice

Adhesive interactions between tumor cells and host tissue occur at several stages of metastasis. Such interactions might be inhibited by microbial metabolites resembling the binding regions of matrix molecules. Certain metabolite sequences including Gly, Asp, Arg, and Ser (GAAS) proved to be critical for cell interactions, e.g. with fibronectin. In vitro, the rosette formation of murine pulmonary cells and sarcoma L-1 cells decreased significantly in the presence of Propionibacterium acnes-metabolites rich in GAAS. In vivo, coinjection of Propionibacterium acnes-metabolites and sarcoma L-1 cells significantly inhibited the formation of lung colonies in BALB/c mice. The inhibition of lung colonization by these metabolites appeared to be noncytotoxic and obviously did not result from impairment of cellular tumorigenicity.

Bacteria of human physiological microflora liberate immunomodulating peptides

Human isolates of Propionibacterium acnes and Staphylococcus saprophyticus could be shown to liberate low molecular weight peptides (MW less than 6.500 D) with immunomodulating activity. FACS analyses of BALB/c-mouse lymphoid cells from the thymus and spleen revealed an enhanced percentage of T-helper cells after peptide administration. Intestinal microflora decontamination of BALB/c-mice considerably reduced immune cell function and lymphatic tissue proliferation. Apparently, lack of peptide production or liberation correlated to immunosuppression. Substitution of peptides (from P. acnes or S. saprophyticus) to decontaminated mice reconstituted immune cell function and proliferation. Cortisone-resistant thymocytes were used as an experimental equivalent of functional cells in the thymus. Thus, cortisone treatment of BALB/c-mice significantly reduced the number of thymocytes, however, administration of microbial peptides restored the thymus population.