Human cytokine responses induced by gram-positive cell walls of normal intestinal microbiota

Effects of Vigiis 101-LAB on a healthy population's gut microflora, peristalsis, immunity, and anti-oxidative capacity: A randomized, double-blind, placebo-controlled clinical study

Vigiis 101-LAB capsules are produced from the fermentation of Lactobacillus paracasei subsp. paracasei NTU 101. We tested effects of Vigiis 101-LAB capsules I or II (5 or 10 billion CFU/day, respectively) on gut microflora in clinical trial I, and on peristalsis, immunity, and anti-oxidative capacity in clinical trial II, during a 4-week randomized, double-blind, placebo-controlled, adaptive-design study. In trial I, 36 subjects were divided into capsule I and placebo groups. After 4 weeks, Bifidobacterium spp. and Lactobacillus spp. counts were significantly higher in the feces of treatment subjects, with increases of 4.01- and 4.25-fold, respectively. In trial II, 52 subjects were divided into capsule II and placebo groups. After 4 weeks, the treatment group was found to have improved motility, decreased food transit time, and significantly increased immunoglobulin G, immunoglobulin M, and antioxidant activity. Thus, daily administration of Vigiis 101 capsule II can improve peristalsis, immunity, and anti-oxidative capacity.

Lifestyle alters GUT-bacteria function: Linking immune response and host

Microbiota in human is a "mixture society" of different species (i.e. bacteria, viruses, funguses) populations with a different way of relationship classification to Human. Human GUT serves as the host of the majority of different bacterial populations (GUT flora, more than 500 species), which are with us ("from the beginning") in an innate manner known as the commensal (no harm to each other) and symbiotic (mutual benefit) relationship. A homeostatic balance of host-bacteria relationship is very important and vital for a normal health process. However, this beneficial relationship and delicate homeostatic state can be disrupted by the imbalance of microbiome-composition of gut microbiota, expressing a pathogenic state. A strict homeostatic balance of microbiome-composition strongly depends on several factors; 1- lifestyle, 2- geography, 3- ethnicities, 4- "mom" as prime of the type of bacterial colonization in infant and 5- the disease. With such diversity in individuals combined with huge number of different bacterial species and their interactions, it is wise to perform an in-depth systems biology (e.g. genomics, proteomics, glycomics, and etcetera) analysis of personalized microbiome. Only in this way, we are able to generate a map of complete GUT microbiota and, in turn, to determine its interaction with host and intra-interaction with pathogenic bacteria. A specific microbiome analysis provides us the knowledge to decipher the nature of interactions between the GUT microbiota and the host and its response to the invading bacteria in a pathogenic state. The GUT-bacteria composition is independent of geography and ethnicity but lifestyle well affects GUT-bacteria composition and function. Microbiome knowledge obtained by systems biology also helps us to change the behavior of GUT microbiota in response to the pathogenic microbes as protection. Functional microbiome changes in response to environmental factors will be discussed in this review.

Immune system stimulation by probiotic microorganisms

Probiotic organisms are claimed to offer several functional properties including stimulation of immune system. This review is presented to provide detailed informations about how probiotics stimulate our immune system. Lactobacillus rhamnosus GG, Lactobacillus casei Shirota, Bifidobacterium animalis Bb-12, Lactobacillus johnsonii La1, Bifidobacterium lactis DR10, and Saccharomyces cerevisiae boulardii are the most investigated probiotic cultures for their immunomodulation properties. Probiotics can enhance nonspecific cellular immune response characterized by activation of macrophages, natural killer (NK) cells, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in strain-specific and dose-dependent manner. Mixture and type (gram-positive and gram-negative) of probiotic organisms may induce different cytokine responses. Supplementation of probiotic organisms in infancy could help prevent immune-mediated diseases in childhood, whereas their intervention in pregnancy could affect fetal immune parameters, such as cord blood interferon (IFN)-γ levels, transforming growth factor (TGF)-β1 levels, and breast milk immunoglobulin (Ig)A. Probiotics that can be delivered via fermented milk or yogurt could improve the gut mucosal immune system by increasing the number of IgA(+) cells and cytokine-producing cells in the effector site of the intestine.

Role of natural killer and dendritic cell crosstalk in immunomodulation by commensal bacteria probiotics

A cooperative dialogue between natural killer (NK) cells and dendritic cells (DCs) has been elucidated in the last years. They help each other to acquire their complete functions, both in the periphery and in the secondary lymphoid organs. Thus, NK cells' activation by dendritic cells allows the killing of transformed or infected cells in the periphery but may also be important for the generation of adaptive immunity. Indeed, it has been shown that NK cells may play a key role in polarizing a Th1 response upon interaction with DCs exposed to microbial products. This regulatory role of DC/NK cross-talk is of particular importance at mucosal surfaces such as the intestine, where the immune system exists in intimate association with commensal bacteria such as lactic acid bacteria (LAB). We here review NK/DC interactions in the presence of gut-derived commensal bacteria and their role in bacterial strain-dependent immunomodulatory effects. We particularly aim to highlight the ability of distinct species of commensal bacterial probiotics to differently affect the outcome of DC/NK cross-talk and consequently to differently influence the polarization of the adaptive immune response.

Adherence and cytokine induction in Caco-2 cells by bacterial populations from a three-stage continuous-culture model of the large intestine

Adherence of bacteria to epithelial cells is an important step in colonization and immune modulation in the large bowel. The aims of this study were to use a three-stage continuous-culture system (CCS) to investigate how environmental factors affect bacterial attachment to Caco-2 cells and modulation of cytokine expression by gut microorganisms, including a probiotic Bifidobacterium longum strain, DD2004. The CCS simulated environmental conditions in the proximal large intestine (vessel 1 [V1]) and distal colon (V2 and V3) at two different system retention times (R) within the range of normal colonic transits (20 and 60 h). The model was inoculated with human fecal material, and fluorescence in situ hybridization (FISH) was used to characterize microbial populations and to assess bacterial attachment to Caco-2 cells. Real-time quantitative PCR (qPCR) was employed to measure cytokine gene expression following challenge with bacteria from different components of the CCS in the presence and absence of B. longum. At an R of 60 h, bacterial adherence increased from V1 to V3, but this trend was reversed at an R of 20 h. Atopobia were the predominant adherent organisms detected at both system retention times in each culture vessel. Modulation of transforming growth factor β1 (TGF-β1), interleukin 6 (IL-6), and IL-18 gene expression by CCS bacteria was marked at an R of 60 h, while at an R of 20 h, IL-4, IL-10, TGF-β2, IL-1α, and tumor necrosis factor alpha (TNF-α) were significantly affected. The addition of B. longum affected cytokine expression significantly at both retention times. This study demonstrates that environmental determinants regulate the adherence properties of intestinal bacteria and their abilities to regulate cytokine synthesis.

Probiotic modulation of dendritic cells and T cell responses in the intestine

Over the past decade it has become clear that probiotic and commensal interactions with mucosal dendritic cells in the lamina propria or epithelial cells lining the mucosa can modulate specific functions of the mucosal immune system. Innate pattern-recognition receptors such as TLRs, NLRs and CLRs play a crucial role in the host recognition of probiotics and other microorganism. Signalling via these receptors directly influences the chemokine and cytokine response of dendritic cells as well as the crosstalk between the epithelium and the immune cells in the lamina propria. This can influence the population of effector and regulatory T cell subsets in the mucosa. Immune assays with probiotics have shown that the in vitro immune response is both species and strain-specific. Such assays may be useful for the selection of probiotic strains that have beneficial effects on the regulation of intestinal inflammation but more comparative studies are needed to confirm recent findings. A better understanding of the molecular mechanisms of probiotics, the effect of dose, and frequency of administration on microbial sampling by mucosal APC will also help to clarify the value of immune assays as selection criteria for probiotics.

Lactobacillus strains differentially modulate cytokine production by hPBMC from pollen-allergic patients

The objective of this study was to assess the potential immunomodulatory effect of six Lactobacillus strains on human peripheral blood mononuclear cells (hPBMC) isolated from allergic patients. hPBMC from patients allergic to birch pollen or grass pollen were cultured in vitro in the presence or absence of selective bacterial strains. Cultures were left unstimulated or stimulated with αCD3/αCD28 or Bet v 1. After 1, 4 and 8 days, cells and culture supernatants were harvested and the effect on cellular proliferation and the supernatant levels of several cytokines was assessed. All strains had the ability to repress IL-13 production but did show a differential effect on IFN-γ induction. Both strains B223 and B1697 showed a lower IFN-γ, IL-12 and TNF-α induction as compared with the other tested strains. Strain B633 showed the best proliferation-suppressive properties in αCD3/αCD28-stimulated cells. Suppression of the T-helper type 2 (Th2) cytokine induction and induction of the Th1 cytokine production by specific strains might be beneficial for allergic patients having a disturbed Th1/Th2 immune balance. Furthermore, hPBMC of patients with seasonal allergy outside the pollen season can be used to determine the immunomodulatory activities of probiotic bacteria.

Antigenic proteins of Lactobacillus acidophilus that are recognised by serum IgG antibodies in children with type 1 diabetes and coeliac disease

Immune responses to lactobacilli have been so far insufficiently investigated in patients with autoimmune diseases. We used whole-cell lysate of an indigenous Lactobacillus acidophilus strain isolated from an Estonian child to study serum IgG antibodies in children groups with type 1 diabetes [insulin dependent diabetes mellitus (IDDM)] (n = 21, age 4-18 yr) and with acute coeliac disease (CD) (n = 20, age 0.6-15 yr) and to compare the results with the controls (n = 24, age 2-17 yr). We found that our developed 1-D immunoblot assay readily enables to reveal antibodies against 28 L. acidophilus antigenic proteins in patients' and controls' sera. As verified by immunoproteomics analysis with 2-D and LC ESI-MS/MS the antigens of L. acidophilus were mainly common cytoplasmic proteins GroEL (HSP60), enolase, transcription factor EF-Ts and EF-Tu. However, in addition we identified formyl-CoA transferase being target for antibodies in every tested IDDM patients' serum. We have characterized for the first time the antigenic profile of L. acidophilus whole-cell lysate using sera from children with IDDM, CD, and controls. The different prevalence of reactions against tested antigens in patients and controls sera may indicate significant differences in immune system and commensal bacteria cross-talk in these groups.

Differential effects of Lactobacillus acidophilus and Lactobacillus plantarum strains on cytokine induction in human peripheral blood mononuclear cells

Lactic acid bacterial strains have received interest for their immunomodulating activities and potential use in probiotic products. A wide variety of strain-dependent properties have been reported, but comparative studies at the species level are scarce. The objective of this study was to assess the immunomodulatory effect of Lactobacillus species on the cytokine profiles and proliferative response of human peripheral blood mononuclear cells (hPBMC), and in particular, on the comparison between the species Lactobacillus acidophilus and Lactobacillus plantarum. hPBMC from healthy donors were stimulated in the presence or absence of the lactic acid bacteria, and cytokine production, surface marker staining, proliferation and cell death were determined after 1 and 4 days of culture. All Lactobacillus strains tested were capable of inducing the production of interleukin (IL)-1beta, IL-10, interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). The bacterial strains did not differentially influence the amount of proliferating, viable, apoptotic and necrotic cells. Generally, L. plantarum showed a significantly higher induction capacity of IFN-gamma, IL-12 and TNF-alpha compared with L. acidophilus. We conclude that the variation in immunomodulatory effects between species is even larger than the variation between the strains of the same species. In addition, we demonstrate that L. plantarum strains are most potent in skewing the T-cell differentiation toward a putative Th1 response.

Suppressive effect on activation of macrophages by Lactobacillus casei strain Shirota genes determining the synthesis of cell wall-associated polysaccharides

Although many Lactobacillus strains used as probiotics are believed to modulate host immune responses, the molecular natures of the components of such probiotic microorganisms directly involved in immune modulation process are largely unknown. We aimed to assess the function of polysaccharide moiety of the cell wall of Lactobacillus casei strain Shirota as a possible immune modulator which regulates cytokine production by macrophages. A gene survey of the genome sequence of L. casei Shirota hunted down a unique cluster of 10 genes, most of whose predicted amino acid sequences had similarities to various extents to known proteins involved in biosynthesis of extracellular or capsular polysaccharides from other lactic acid bacteria. Gene knockout mutants of eight genes from this cluster resulted in the loss of reactivity to L. casei Shirota-specific monoclonal antibody and extreme reduction of high-molecular-mass polysaccharides in the cell wall fraction, indicating that at least these genes are involved in biosynthesis of high-molecular-mass cell wall polysaccharides. By adding heat-killed mutant cells to mouse macrophage cell lines or to mouse spleen cells, the production of tumor necrosis factor alpha, interleukin-12 (IL-12), IL-10, and IL-6 was more stimulated than by wild-type cells. In addition, these mutants additively enhanced lipopolysaccharide-induced IL-6 production by RAW 264.7 mouse macrophage-like cells, while wild-type cells significantly suppressed the IL-6 production of RAW 264.7. Collectively, these results indicate that this cluster of genes of L. casei Shirota, which have been named cps1A, cps1B, cps1C, cps1D, cps1E, cps1F, cps1G, and cps1J, determine the synthesis of the high-molecular-mass polysaccharide moiety of the L. casei Shirota cell wall and that this polysaccharide moiety is the relevant immune modulator which may function to reduce excessive immune reactions during the activation of macrophages by L. casei Shirota.

Murine immunomodulation of IL-10 and IL-12 induced by new isolates from avian type 2 Lactobacillus acidophilus

Several bacterial and immunogenic factors are involved in the host response to probiotic strains of Lactobacillus . Here, we report the isolation of new intestinal lactobacilli from chicken, with different immunomodulating properties on lymphoid cells from SJL and C57BL/6 mice. Analysis of biochemical markers in the Lactobacillus acidophilus CBA4P, CBA3P, and TPA3P isolates reveal that these bacterial isolates belong to the type 2 prototype, although they differ from each other. The effect of conditioned media (CM) from SJL- and C57BL/6-derived peritoneal macrophages incubated with the 3 sonicated bacterial isolates from chicken, as well as with Lactobacillus rhamnosus 9595, Escherichia coli lipopolysaccharide, or Staphylococcus aureus peptidoglycan were compared. Our results show that the CM of macrophages from C57BL/6 and SJL mice treated with the CBA4P isolate stimulated syngeneic splenic lymphocytes at a level similar to the one induced with CM from peptidoglycan-stimulated macrophages. In contrast, the CM from TPA3P- and CBA3P-treated macrophages promoted low or no stimulation of lymphoid cells. Incubation of splenic cells with CM from macrophages treated with L. rhamnosus or TPA3P led to a relative decrease in the percentages of splenic CD4+ T cells, whereas the relative percentages of B cells increased. The CBA4P and CBA3P isolates induced higher levels of gamma interferon when compared with the TPA3P isolate. The effects of the lactobacilli isolates differed according to the mouse strain used but correlated with the production of macrophagic tumor necrosis factor alpha and interleukins 6, 10, and 12 and with the modulation of the p38 mitogen-activated protein kinase (MAPK). Taken together, these results indicate that the immunomodulating properties of the new L. acidophilus isolates depend on their capacity to induce production of interleukins 10 and 12 by macrophages, which is under genetic control and depends on the p38 MAPK pathway.

Non–digestible oligosaccharides and defense functions: lessons learned from animal models

Animals are constantly exposed to a diversity of health challenges and the gastrointestinal tract (GIT) is a major, if not the principal, site of exposure. Animal models and a limited number of human clinical studies have shown that the assemblages and metabolic activities of the resident bacteria are important determinants of the effectiveness of the various host defense mechanisms and thereby influence the ability of animals to respond to health challenges. The assemblages of bacteria resident in the GIT provide a first line of defense that can exclude invading pathogens, reduce the proliferation of opportunistic pathogens already resident in the GIT, and reduce the availability, carcinogenicity, or toxicity of noxious chemicals. The mucosa of the GIT is a second, multilayered line of defense that includes the mucous and other secretions, the epithelial cells, and immune-associated cells scattered within and under the epithelium. The final line of defense contends with pathogens or noxious chemicals that transcend the mucosal barrier and enter the host and consists of the innate and acquired components of the systemic immune system and the xenobiotic metabolizing enzymes. The lactic acid producing bacteria (LAB) are considered to be immunomodulatory and directly or indirectly influence the GIT and systemic defense functions. Corresponding with this, supplementing the diet with inulin, oligofructose, or other nondigestible oligosaccharides that increase the densities and metabolic capacities of the LAB enhances defense mechanisms of the host, increases resistance to various health challenges, and accelerates recovery of the GIT after disturbances.

Immune responses generated by Lactobacillus as a carrier in DNA immunization against foot-and-mouth disease virus

To exploit Lactobacillus acidophilus as a carrier in DNA immunization against foot-and-mouth disease virus (FMDV), a recombinant eukaryotic expression plasmid (pRc/CMV2-VP1-Rep. 8014) harboring pRc/CMV2 vector, the FMDV VP1 gene, and a replication origin from Lactobacillus plantarum ATCC 8014 strain was constructed. To detect the VP1 protein, pRc/CMV2-VP1-Rep. 8014 was expressed in PK 15 cells and transfected into a L. acidophilus SW1 strain (L. acidophilus SFMD-1). To evaluate the immunization effect of L. acidophilus SFMD-1, anti-FMDV VP1 antibody, T-cell proliferation, antigen-specific delayed-type hypersensitivity (DTH), and tissue distribution were investigated using intramuscular, intraperitoneal, intranasal, and oral administration delivery routes. The results showed that L. acidophilus SFMD-1 was able to elicit a detectable antibody level on day 21. The VP1 antibody levels induced by L. acidophilus SFMD-1 and commercial inactivated FMDV vaccine rose rapidly to 0.84 and 0.70, respectively, by day 42, then sustained a high level by day 49. The route of administration had an impact on the magnitude of the systemic antigen-specific IgG responses, with intramuscularly applied L. acidophilus SFMD-1 generating the greatest FMDV VP1 antibody response, followed by intraperitoneal, intranasal, and oral administration delivery routes. Using the T-cell proliferation assay, the stimulation index of a group immunized with L. acidophilus SFMD-1 reached 2.78 versus 5.08 in a group immunized with pRc/CMV2-VP1-Rep. 8014 plasmid. Mice immunized with L. acidophilus SFMD-1 were able to induce T-cell-mediated antigen-specific DTH. In addition, the VP1 gene was detected in the muscle, kidney, spleen, and heart, but not in the liver. The results demonstrate clearly that Lactobacillus as a carrier is a promising approach of DNA vaccination, and is a potentially guard against FMDV.

Combination treatment of rat adjuvant-induced arthritis with methotrexate, probiotic bacteria Enterococcus faecium, and selenium

The effects of the probiotic bacteria Enterococcus faecium (EF) and selenium were studied on methotrexate (MTX) treatment in rats with adjuvant arthritis. Arthritic rats were treated orally with the following substances: lyophilized EF (15 mg/kg/day, 5 days a week), sodium selenite pentahydrate (SSe; 0.050 mg/kg containing 0.015 mg/kg selenium, 5 days a week), MTX (0.6 mg/kg/week), and their combinations for the period of 50 days from adjuvant application. Levels of serum albumin, serum nitrite/nitrate concentrations, hind paw swelling, arthrogram scores, whole-body bone mineral density (BMD), and bone erosions were evaluated as markers of inflammation and destructive changes associated with arthritis. Long-term preventive treatment with low-dose MTX significantly inhibited the markers of both inflammation and arthritis. EF or SSe when administered singly or in combination had no significant effect on the given parameters in arthritic rats. EF, but not SSe, potentiated the beneficial effects of MTX, which resulted in a more significant reduction of hind paw swelling, arthrogram scores, and whole-body BMD decrease. EF also had a tendency to improve the effect of MTX on serum albumin and nitrite/nitrate concentrations. Our results indicate that EF may increase the preventive effect of MTX treatment in rat adjuvant arthritis by improving its anti-inflammatory and antiarthritic effects.

Induction of a Regulatory Phenotype in Human CD4+ T Cells by Streptococcal M Protein

Regulatory T cells (Tregs) participate in the control of the immune response. In the human system, an IL-10-secreting, T regulatory type 1 cell (Tr1)-like subset of Tregs can be induced by concurrent cross-linking of the TCR and CD46 on naive CD4(+) T cells. Because many viral and bacterial pathogens, including the major human pathogen Streptococcus pyogenes, bind to CD46, we asked whether this bacterium can directly induce Tr1-like cells through the streptococcal ligand for CD46, the M protein. The M5 and M22 proteins were found to induce T cells to develop into the IL-10-producing Tr1-like phenotype. Moreover, whole M5-expressing bacteria, but not isogenic M-negative bacteria, led to proliferation and IL-10 secretion by T cells. The interaction between the M5 protein and T cells was dependent on CD46 and the conserved C repeat region of M5. Supernatants derived from T cells stimulated with M proteins or M protein-expressing bacteria suppressed bystander T cell proliferation through IL-10 secretion. In addition, activation of CD46 through streptococcal M protein induced the expression of granzyme B, providing a second means for these cells to regulate an immune response. These findings suggest that binding to CD46 and exploiting its signaling pathway may represent a strategy employed by a number of important human pathogens to induce directly an immunosuppressive/regulatory phenotype in T cells.

Antagonistic activities of lactobacilli and bifidobacteria against microbial pathogens

The gastrointestinal tract is a complex ecosystem that associates a resident microbiota and cells of various phenotypes lining the epithelial wall expressing complex metabolic activities. The resident microbiota in the digestive tract is a heterogeneous microbial ecosystem containing up to 1 x 10(14) colony-forming units (CFUs) of bacteria. The intestinal microbiota plays an important role in normal gut function and maintaining host health. The host is protected from attack by potentially harmful microbial microorganisms by the physical and chemical barriers created by the gastrointestinal epithelium. The cells lining the gastrointestinal epithelium and the resident microbiota are two partners that properly and/or synergistically function to promote an efficient host system of defence. The gastrointestinal cells that make up the epithelium, provide a physical barrier that protects the host against the unwanted intrusion of microorganisms into the gastrointestinal microbiota, and against the penetration of harmful microorganisms which usurp the cellular molecules and signalling pathways of the host to become pathogenic. One of the basic physiological functions of the resident microbiota is that it functions as a microbial barrier against microbial pathogens. The mechanisms by which the species of the microbiota exert this barrier effect remain largely to be determined. There is increasing evidence that lactobacilli and bifidobacteria, which inhabit the gastrointestinal microbiota, develop antimicrobial activities that participate in the host's gastrointestinal system of defence. The objective of this review is to analyze the in vitro and in vivo experimental and clinical studies in which the antimicrobial activities of selected lactobacilli and bifidobacteria strains have been documented.

Cell surface-associated elongation factor Tu mediates the attachment of Lactobacillus johnsonii NCC533 (La1) to human intestinal cells and mucins

The aim of this work was to identify Lactobacillus johnsonii NCC533 (La1) surface molecules mediating attachment to intestinal epithelial cells and mucins. Incubation of Caco-2 intestinal epithelial cells with an L. johnsonii La1 cell wall extract led to the recognition of elongation factor Tu (EF-Tu) as a novel La1 adhesin-like factor. The presence of EF-Tu at the surface of La1 was confirmed by analysis of purified outer surface protein extract by immunoblotting experiments, by electron microscopy, and by enzyme-linked immunosorbent assays of live bacteria. Furthermore, tandem mass spectrometry analysis proved that EF-TU was expressed at the La1 surface as an intact molecule. Using recombinant La1 EF-Tu protein, we were able to determine that its binding to intestinal cells and to mucins is pH dependent. Competition experiments suggested that EF-Tu has an important role in La1 mucin binding capacity. In addition, immunomodulation studies performed on HT29 cells showed that EF-Tu recombinant protein can induce a proinflammatory response in the presence of soluble CD14. Our in vitro results indicate that EF-Tu, through its binding to the intestinal mucosa, might participate in gut homeostasis.

Comparison of Type 1 and Type 2 Cytokine Production by Mononuclear Cells Cultured With Streptococcus mutans and Selected Other Caries Bacteria

A feature of pulpal immune responses is the predominance of type 1 cytokine mRNA under shallow caries and a mixed (type 1/type 2) profile under deep caries. These results prompted an examination of the cytokine profiles induced by bacteria in shallow caries (Streptococcus mutans and Actinomyces viscosus) and deep caries (Lactobacillus casei, Pseudoramibacter alactolyticus, and Prevotella intermedia). All isolates induced interferon-gamma and interleukin-10, whereas interleukin-4 and interleukin-2 titers were low to undetectable. S. mutans was the most potent and persistent interferon-gamma inducer. Differences in interleukin-10 were apparent at low doses but were less dramatic, with L. casei the dominant producer. S. mutans induced substantially more interferon-gamma than interleukin-10 over all doses and time points, suggesting strong type 1 polarization. P. alactolyticus induced significantly more interleukin-10 than interferon-gamma at higher concentrations, suggesting polarization toward type 2. A similar amount of interferon-gamma and interleukin-10 induced by L. casei, A. viscosus, and P. intermedia reflected a mixed profile. A better understanding of pulpal immune response to caries bacteria may enable us to develop an immune system-based pulp therapy in the future.

Effects of probiotic therapy on the activity and activation of mild rheumatoid arthritis--a pilot study

OBJECTIVE

To study the effects of Lactobacillus rhamnosus GG (LGG) on rheumatoid arthritis (RA).

METHODS

Twenty-one RA patients were randomised to receive 2 capsules of LGG or a placebo twice daily in double-blind fashion for 12 months. Arthritis activity was evaluated by clinical examination, HAQ index, and laboratory tests (e.g. ESR, CRP, pro- and anti-inflammatory cytokines).

RESULTS

There were no statistical differences in the clinical parameters, biochemical variables and HAQ index between the study groups over the intervention period. The mean number of tender and swollen joints decreased from 8.3 to 4.6 in the Lactobacillus group and from 5.5 to 4.8 in the placebo group (p = 0.41). According to the global assessment the RA activity was reduced in 71% (LGG group) vs. 30% (controls) (p = 0.15). Serum IL-1 beta increased slightly in the LGG group (p = 0.07), but no differences were seen in IL-6, TNF-alpha, MPO, IL-10 or 1L-12.

CONCLUSIONS

Although there were no statistical significant differences in the activity of RA, more subjects in the LGG group reported subjective well being. More studies on the effects of probiotic bacteria in RA are needed.

Role of peptidoglycan subtypes in the pathogenesis of bacterial cell wall arthritis

BACKGROUND

Bacterial cell wall (CW) arthritis develops in susceptible strains of rats after a single intraperitoneal injection of the CW from certain bacterial species, both pathogenic and non-pathogenic. For the development of chronic bacterial CW arthritis, the structure of the bacterial peptidoglycan (PG) has been found to be decisive.

OBJECTIVE

To define the role of PG subtypes in the pathogenesis of chronic bacterial CW arthritis.

METHOD

Arthritis was induced with CWs of Lactobacillus plantarum, L casei B, L casei C, and L fermentum. Gas chromatography-mass spectrometry was used to measure the presence of CW derived muramic acid in the liver and to determine PG subtypes. CWs were also tested for their resistance to lysozyme in vitro.

RESULTS

These results and those published previously indicate that PGs of CWs which induce chronic arthritis, no matter whether they were derived from strains of Streptococcus, Bifidobacterium, Collinsella, or Lactobacillus, all have lysine as the third amino acid of the PG stem peptide, representing PG subtypes A3alpha and A4alpha. Those strains which induce only transient acute arthritis or no arthritis at all do not have lysine in this position, resulting in different PG subtypes.

CONCLUSIONS

In vivo degradation of only those PGs with the subtypes A3alpha and A4alpha leads to the occurrence of large CW fragments, which persist in tissue and have good proinflammatory ability. CWs with other PG subtypes, even if they are lysozyme resistant, do not cause chronic arthritis, because the released fragments are not phlogistic. It is emphasised that a variety of microbial components not causing inflammation have been found in animal and human synovial tissue.

Normal intestinal microbiota in the aetiopathogenesis of rheumatoid arthritis

A series of observations have led to the hypothesis that normal intestinal microbiota in patients with rheumatoid arthritis may harbour, for genetic reasons, bacteria with cell walls capable of inducing arthritis. Differences occur between bacterial species, and even between strains of a single species, because some cell walls induce experimental chronic arthritis, whereas some others induce only a transient acute arthritis or no arthritis at all. In susceptible subjects, with continuous seeding of bacterial products from the gut, the synovial inflammation is followed by erosion, exposition of cartilage antigens, and self perpetuating chronic arthritis.

Bacterial components in the synovial tissue of patients with advanced rheumatoid arthritis or osteoarthritis: analysis with gas chromatography-mass spectrometry and pan-bacterial polymerase chain reaction

OBJECTIVE

To study the presence of bacterial components in the synovial tissue (ST) of patients with advanced rheumatoid arthritis (RA).

METHODS

ST was collected during joint surgery from 41 RA patients. Tissue from 39 patients with osteoarthritis (OA), 4 patients with undifferentiated inflammatory arthritis (UA), and 3 cases of accidental deaths served as controls. The pan-bacterial polymerase chain reaction (PCR) with primers for the 23S ribosomal RNA (rRNA) and 16S rRNA genes was used to detect bacterial DNA. In addition, synovial fluid (SF) samples from patients with chlamydial reactive arthritis (ReA) were also examined by the same method. The positive controls, bacterial DNA or ST spiked with different living bacteria, were analyzed alongside clinical samples. Most of the ST samples were also analyzed by gas chromatography-mass spectrometry (GC-MS) for determining the presence of bacteria-derived muramic acid. Strict precautions were followed in the clinics and the laboratory to prevent contamination.

RESULTS

In GC-MS analysis, muramic acid was observed in the ST from 4 of 35 RA patients and from 2 of 14 OA patients, but not in ST from 2 patients with UA and 3 cadavers. Bacterial DNA was not detected by either one of the PCR primers used in ST from 42 patients with RA and 39 patients with OA. However, 5 of 15 SF samples from ReA patients were PCR positive. The sensitivity of GC-MS to detect muramic acid was 2 pg/injected amount (227 pg muramic acid/mg ST), and that of the pan-bacterial PCR was 2-20 bacteria colony forming units/reaction.

CONCLUSION

These results indicate that a bacterial component, muramic acid, is detectable by GC-MS in ST from a few patients with advanced RA or OA. However, no bacterial DNA was detectable by PCR.

Adjuvant properties and colonization potential of adhering and non-adhering Lactobacillus spp following oral administration to mice

This study aimed to determine whether adhesive strains of Lactobacillus possessed an increased ability to colonize the gastrointestinal tract and to examine the adjuvant capacities of these strains for the 50000 molecular-mass fragment C of tetanus toxin (TTFC) following oral administration. The three strains used in this study showed different patterns of adhesion to tissue from all regions of the gastrointestinal tract, with two strains adhering in high numbers and one strain showing negligible association with all tissue types. The colonization patterns in the gastrointestinal tract of C57BL/6 mice following oro-gastric dosing was also monitored, and it was found that adhesive Lactobacillus strains could be detected for at least 24 h, in association with either fecal material and/or with gastrointestinal tissue or contents. In addition, mice were given an oro-gastric dose of the lactobacilli (5 x 10(8) colony forming units) with TTFC (10 and 50 micro g), and the serum-specific IgM and IgG antibody responses monitored in serum. The adhesive strains, which persisted within the gastrointestinal tract for at least 24 h, showed enhanced antigen-specific serum IgG and IgM antibody responses in comparison to a non-adhesive strain that failed to be detected in the gastrointestinal tract. Adhesion to the gastrointestinal tract is a factor affecting the capacity of lactobacilli to persist within the gastrointestinal tract and to act as an adjuvant for orally administered antigen.

Suppression of antigen-specific lymphocyte proliferation by Gram-positive bacterial cell walls

It is largely unknown how bacterial cell walls (BCW) modulate human immune responses. In the present work the effect of Gram-positive BCW on lymphocyte proliferation responses towards several microbial antigens (Ag) or mitogens was studied. Gram-positive BCW were derived from four indigenous bacterial strains and from one pathogen (Streptococcus pyogenes). All BCW preparations used non-specifically suppressed the proliferation responses of peripheral blood mononuclear cells (PBMC) against bacterial and viral Ag, but not against mitogens. Both lymphocytes and macrophages or their secreted products mediated the suppressive effects of BCW, which were not IL-10 dependent. Furthermore, the expression of HLA-DR and CD86 on monocytes/macrophages was downregulated by BCW. Unlike in LPS-induced suppression, the CD14 pathway was not used by BCW of Lactobacillus casei (L.c.). The observed results indicate that Gram-positive BCW suppress antigen-specific lymphocyte proliferation through several mechanisms. This non-specific immunosuppression might be a general function of BCW in the bacteria-host interaction, being of importance for bacterial survival and pathogenicity.

Low ileal interleukin 10 concentrations are predictive of endoscopic recurrence in patients with Crohn's disease

BACKGROUND

Endoscopic recurrence after surgery in Crohn's disease is frequent and unpredictable. Abnormal intestinal production of pro- (interleukin (IL)-1 beta, tumour necrosis factor alpha (TNF-alpha)) and anti- (IL-10) inflammatory cytokines has been associated with severe outcome in experimental models of colitis.

PATIENTS AND METHODS

We evaluated if ileal TNF-alpha, IL-1 beta, or IL-10 mRNA levels measured at the time of surgery predict endoscopic recurrence, and if ileal IL-10 levels are associated with particular IL-10 promoter alleles. Ileal biopsies were obtained peroperatively from the healthy neoileum of patients undergoing a right ileocolectomy for Crohn's disease. Mucosal TNF-alpha, IL-1 beta, and IL-10 mRNA levels were quantified by competitive polymerase chain reaction. A cut off value was determined using a receiver operating curve. IL-10.G promoter haplotypes were analysed using a polymorphic dinucleotide repeat in the IL-10 promoter region.

RESULTS

Three months after surgery, 53% of patients had endoscopic recurrence while 47% remained free of disease. The risk of endoscopic recurrence correlated with ileal IL-10 mRNA concentrations (r(2)=0.81). Endoscopic recurrence occurred more frequently in patients classified as low IL-10 producers than in those that were high producers (80% v 40%) (p=0.02). Patients with at least one of the two alleles G7-8 or G10-13 produced, respectively, higher (p=0.006) and lower (p=0.029) ileal IL-10 mRNA. The distribution of IL-10.G microsatellite genotypes was similar in patients with or without endoscopic recurrence.

CONCLUSION

Low ileal IL-10 mRNA concentration is a good marker of endoscopic recurrence in Crohn's disease but the distribution of IL-10.G haplotypes cannot predict the postoperative evolution of the disease.

Experimental chronic arthritis and granulomatous inflammation induced by bifidobacterium cell walls

Effects of cell walls (CWs) from two almost identical strains of Bifidobacterium adolescentis were studied in rats, using three different doses. A single i.p. injection of both CWs triggered a long-lasting arthritis with CW degradation products present in the joint tissue. Histologically, the arthritis was characterized by inflammatory cells, synovial hyperplasia, pannus formation and bone erosion, closely resembling human rheumatoid arthritis (RA). In addition, CWs of the other strain induced a remarkable granuloma formation in the spleen and liver. Both CWs have the same peptidoglycan (PG) type A4alpha/beta, but differ from each other in three aspects. CW of the granuloma inducing strain: firstly has more lysine and less ornithine in PG stem peptides; secondly is more resistant to lysozyme degradation, and thirdly is better retained in the spleen. All these in comparison to the other strain used. Such characteristics are associated with the capacity to induce chronic arthritis, but it remains open how crucial they are for the granuloma formation.

Can immunoregulatory lactic acid bacteria be used as dietary supplements to limit allergies?

Studies in gnotobiotic animals have suggested that the intestinal bacterial flora may play an important role in priming the immune system during ontogeny to limit dysfunctional responses, including allergy. Prospective clinical studies have identified a higher incidence of allergy expression in early childhood among children who have low enteric populations of lactic acid bacteria (LAB), such as lactobacilli and bifidobacteria, further supporting a role for gut-colonizing bacteria in regulating immunological atopy. There is some evidence to suggest that supplementing the human diet with probiotic LAB might combat both allergy development and expression of atopy in allergy sufferers; however, definitive information, in the form of controlled intervention trials, remains scant. Recent immunological evidence has indicated that certain strains of LAB can stimulate the production of type I and II interferons and pro-interferon monokines (IL-12 and IL-18), following contact with the immune system; therefore, probiotic forms of immunoregulatory LAB could be used as dietary supplements to modify the gut microflora and provide pro-T helper cell 1 (Th1) STAT-activating signals sufficient to deviate the immune phenotype and correct the Th2-type bias which promotes allergy. This review outlines the clinical and laboratory evidence of a role for LAB in combating allergies, and attempts to explain this phenomenon in terms of our current understanding of immunoregulatory signals produced by gut-colonizing microbes.

Anti-allergy properties of fermented foods: an important immunoregulatory mechanism of lactic acid bacteria?

Clinical reports have suggested that dietary consumption of fermented foods, such as yogurt, can alleviate some of the symptoms of atopy and might also reduce the development of allergies, possibly via a mechanism of immune regulation. Controlled studies have indicated that consumption of fermented milk cultures containing lactic acid bacteria (LAB) can enhance production of Type I and Type II interferons at the systemic level. In animal models, LAB have been shown to promote interferon expression, and to reduce allergen-stimulated production of IL-4 and IL-5 in some cases. Recent results have shown that LAB are potent inducers of pro-interferon monokines (IL-12 and IL-18), and that cytokine secretion is stimulated by the interaction of Gram-positive cell wall components with surface receptors of mononuclear phagocytes, via NF-kappa B and STAT signalling pathways. However, it is clear that the extent and quality of LAB-induced immunoregulation is strain-dependent. This review discusses the clinical and laboratory evidence for anti-allergy properties of fermented foods, and proposes a model for the mechanism by which some well-defined strains of immunoregulatory LAB might down-regulate a Th2 allergic phenotype.

From reactive arthritis to rheumatoid arthritis

Reactive arthritis was initially described as a sterile synovitis, without microbial components present in the joint tissue. It has, however, become evident that bacterial degradation products, and even bacterial DNA, are present in the synovium of patients with this disease. Since intestinal pathogens are important causes of reactive arthritis, and since cellular homing allows transport of bacterial products from the gut to synovium, we have approached the etiology of rheumatoid arthritis from this point of view. A series of observations has led to a hypothesis that patients with rheumatoid arthritis might favour, for genetic reasons, intestinal bacteria which are capable of inducing arthritis. In the long-run, with continuous seeding of bacterial products from the gut, the synovial inflammation is followed by erosion, exposition of cartilage antigens, and autoimmunity.

Cytokine production in arthritis susceptible and resistant rats: a study with arthritogenic and non-arthritogenic Lactobacillus cell walls

The basis of the different susceptibility to bacterial cell wall-induced arthritis between Lewis and Fischer rats is unclear. Likewise, it is not known why cell walls of some species of Lactobacillus are arthritogenic and those of others are not. With these two questions in mind, we investigated the role of anti-inflammatory (interleukin (IL)-10, IL-4) and proinflammatory (tumour necrosis factor (TNF)-alpha, IL-1 beta) cytokines in Lewis and Fischer rats injected intraperitoneally with cell walls from arthritogenic or nonarthritogenic species of Lactobacillus. Cytokine levels in the serum and in vitro production by peritoneal macrophages and splenocytes were studied. The results obtained indicate that the differences in the production of IL-10, IL-4, TNF-alpha or IL-1 beta do not explain the difference in the arthritis susceptibility between Lewis and Fischer rats. Likewise, the arthritogenicity of different Lactobacillus cell walls appears not to be dependent on their capacity to stimulate cytokine production.

Bacterial translocation can increase plasma corticosterone and brain catecholamine and indoleamine metabolism

The potential contribution of stress-induced bacterial translocation to the activation of the hypothalamo-pituitary-adrenocortical (HPA) axis and brain biogenic amines was assessed. Mice were restrained for various periods, and brain concentrations of tryptophan, catecholamines, serotonin, and their metabolites, plasma corticosterone, and the translocation of viable bacteria from the gastrointestinal tract to the mesenteric lymph nodes, spleen, and liver were measured. Restraint induced the translocation of indigenous gram-positive bacteria in only a small proportion of animals, but translocation of gram-negative bacteria did not occur. Restraint induced short-lived increases in plasma corticosterone and brain amine metabolism, whereas bacterial translocation was slower and persisted long after the HPA axis and neurochemical responses had dissipated. When mice were infected with Salmonella typhimurium, spontaneous translocation occurred and plasma corticosterone, interleukin-6 concentrations, and brain catecholamine and indoleamine metabolism were elevated. These findings indicate that the translocation of indigenous gastrointestinal bacteria did not contribute to the HPA axis and neurochemical changes induced by restraint. However, translocation of nonindigenous S. typhimurium with or without restraint did induce HPA and neurochemical responses.

Cytokine induction by Streptococcus mutans and pulpal pathogenesis

Chronic pulpal inflammation under caries appears to be elicited by bacterial antigens that diffuse into the pulp through dentinal tubules. This prompted the hypothesis that cytokines elicited by antigens from Streptococcus mutans, which frequently dominates shallow lesions, could play a major role in eliciting the initial T-cell response in the pulp. To test this, we examined the ability of S. mutans to stimulate T cells and elicit cytokines and used Lactobacillus casei, which often predominates in deep carious lesions where B cells and plasma cells predominate, as a control. In addition, the presence of cytokines in the pulp was analyzed at the mRNA level. S. mutans elicited potent gamma interferon (IFN-gamma) responses in peripheral blood mononuclear cell cultures and reduced the CD4/CD8 ratio by promoting CD8(+) T cells. Multiple inflammatory cytokine mRNAs (IFN-gamma, interleukin 4 [IL-4], and IL-10) were detected in human dental pulp. A higher prevalence of IFN-gamma (67%) than IL-4 (19%) or IL-10 (29%) was obtained in shallow caries, suggesting a type 1 cytokine mechanism in early pulpitis where S. mutans predominates. In contrast, in deep caries no differences in cytokine frequency were observed. Furthermore, the presence of IFN-gamma in the pulp correlated with the presence of S. mutans. The extraordinary induction of type 1 cytokines and the preferential activation of CD8(+) T cells by S. mutans offers an explanation for the etiology of the CD8(+) T-cell-dominant lesion in early pulpitis and suggests that S. mutans may have a major impact on the initial lesion and pulpal pathology.