Characterisation of Eubacterium cell wall: peptidoglycan structure determines arthritogenicity

Probiotics as efficient immunopotentiators: translational role in cancer prevention

Accumulating evidences indicate that some diseases are triggered by abnormalities of the gut microbiota. Among these, immune-related diseases can be the promising targets for probiotcs. Several studies have proved the efficacy of probiotics for preventing such diseases including cancers, infections, allergies, inflammatory bowel diseases and autoimmune diseases. Lactobacillus casei strain Shirota (LcS) is one of the most popular probiotics, benefits of which in health maintenance and disease control have been supported by several science-based evidences. This review summarizes human clinical trials with this probiotic against cancer development and also discusses the possible immunomodulatory mechanisms by which LcS exerts anti-cancer activity.

The effectiveness of Echinacea extract or composite glucosamine, chondroitin and methyl sulfonyl methane supplements on acute and chronic rheumatoid arthritis rat model

The study aimed to investigate the effect of the oral administration for 15 days of either Echinacea (E) or genuphil (a composite of chondroitin sulphate, glucosamine and methyl sulfonyl methane [GCM]) nutraceutical supplements on female rat model of acute or chronic arthritis induced by bacterial outer membrane protein (OMP) from faecal flora of healthy and rheumatic humans. Anti-cyclic citrullinated peptide (anti-CCP2), C-reactive protein (CRP) and rheumatoid factor (RF) values increased ( p < 0.05) in both arthritic groups as compared to normal values. The rheumatic markers anti-CCP2, CRP and RF values decreased significantly in E- and GCM-treated groups compared to arthritic none-treated acute or chronic groups. The results of RF values of GCM-treated groups in acute and chronic models decreased exhibiting no statistical difference compared with the normal value. Histological examinations of the hind paw sections revealed moderate inflammation, oedema and mild proliferation of synovial cells in acute arthritic rats and more damage to cartilage and bone with severe inflammation in chronic ones. Echinacea acute treated group showed edema with proliferated synovial membrane and partial damage in cartilage and bone. While in the E -chronic treated group, rough edge with destructed cartilage and bone existed. However, the acute GCM group revealed mild cartilage damage. But the chronic GCM group showed mild synovial cells proliferation and revealed no inflammation with mild cartilage damage edge. Results demonstrated the OMP arthropathic property and through promising light on arthritis treatment using E- or GCM, with the advantage of GMC results over that of E -. The composite GCM is needed for further studies over the dose and duration to assess its preventive effects against the bacterial OMP arthrogenicity.

Peptidoglycan from lactobacilli inhibits interleukin-12 production by macrophages induced by Lactobacillus casei through Toll-like receptor 2-dependent and independent mechanisms

We previously showed that Lactobacillus strains having a rigid cell wall resistant to intracellular digestion can stimulate macrophages to induce large a quantity of interleukin-12 (IL-12). In this study, we examined the influence of lactobacilli and bacterial cell wall components on IL-12 production by macrophages that was induced by Lactobacillus casei, which has a rigid cell wall. Easily digestible lactobacilli such as Lactobacillus johnsonii and Lactobacillus plantarum or their intact cell walls (ICWs) weakly or very weakly induced IL-12 production by macrophages, and inhibitedL. casei-induced IL-12 production. While the ICW of L. casei was resistant to intracellular digestion and did not inhibit L. casei-induced IL-12 production, its polysaccharide-depleted ICW, i.e. intact peptidoglycan, was sensitive to intracellular digestion and inhibited L. casei-induced IL-12 production. Furthermore, the peptidoglycans of L. johnsonii, L. plantarum and Staphylococcus aureus also inhibited L. casei-induced IL-12 production. Peptidoglycans from lactobacilli suppressed L. casei-induced expression of IL-12p40 but not IL-12p35 mRNA. Inhibition of IL-12 production by peptidoglycan was mitigated in Toll-like receptor 2 (TLR2)-deficient macrophages compared with the inhibition in wild-type macrophages. A derivative of the minimal structural unit of peptidoglycan (6-O-stearoyl-muramyl dipeptide) recognized by nucleotide-binding oligomerization domain 2 (NOD2) could also suppress L. casei-induced IL-12 production. These findings demonstrate that easily digestible bacteria and peptidoglycan suppress IL-12 production through pattern recognition receptors such as TLR2 and NOD2. IL-12 production in the gut may be negatively regulated by the simultaneous inhibitory actions of various resident bacteria that are susceptible to intracellular digestion.

Hypothalamic nonapeptidergic regulation of cell and tissue homeostasis: interactions of pro- and eukaryotes

Data on the structural-functional organization of the hypothalamic nonapeptidergic neurosecretory system in mammals and its role in regulating the adaptive reactions of animals are presented; reports describing the biological features of interactions between pro- and eukaryotes in in situ conditions and on cultivation and in experimental pathology are summarized. Morphofunctional criteria are established on the basis of contemporary morphological approaches to allow effective evaluation of the range of histoblastic and organotypic potentials of the visceral organs and their compensatory-adaptive capacities realized under hypothalamic neuroendocrine control and seen on interactions with bacterial pathogens. Emphasis is placed on experimental histological grounds for new methods for the complex treatment of wound and purulent-necrotic processes, including the use of hypothalamic nonapeptides (oxytocin).

Bacillus anthracis peptidoglycan stimulates an inflammatory response in monocytes through the p38 mitogen-activated protein kinase pathway

We hypothesized that the peptidoglycan component of B. anthracis may play a critical role in morbidity and mortality associated with inhalation anthrax. To explore this issue, we purified the peptidoglycan component of the bacterial cell wall and studied the response of human peripheral blood cells. The purified B. anthracis peptidoglycan was free of non-covalently bound protein but contained a complex set of amino acids probably arising from the stem peptide. The peptidoglycan contained a polysaccharide that was removed by mild acid treatment, and the biological activity remained with the peptidoglycan and not the polysaccharide. The biological activity of the peptidoglycan was sensitive to lysozyme but not other hydrolytic enzymes, showing that the activity resides in the peptidoglycan component and not bacterial DNA, RNA or protein. B. anthracis peptidoglycan stimulated monocytes to produce primarily TNFα; neutrophils and lymphocytes did not respond. Peptidoglycan stimulated monocyte p38 mitogen-activated protein kinase and p38 activity was required for TNFα production by the cells. We conclude that peptidoglycan in B. anthracis is biologically active, that it stimulates a proinflammatory response in monocytes, and uses the p38 kinase signal transduction pathway to do so. Given the high bacterial burden in pulmonary anthrax, these findings suggest that the inflammatory events associated with peptidoglycan may play an important role in anthrax pathogenesis.

Induction of Interleukin-12 by Lactobacillus Strains Having a Rigid Cell Wall Resistant to Intracellular Digestion

Some strains of lactobacilli can stimulate macrophages and dendritic cells to secrete IL-12, which plays a key role in activating innate immunity. We examined the IL-12-inducing ability of 47 Lactobacillus strains belonging to 10 species in mouse peritoneal macrophages, and characterized the properties important for the induction of IL-12. Although considerable differences in IL-12-inducing ability were observed among the strains tested, almost all strains belonging to the Lactobacillus casei group (L. casei, Lactobacillus rhamnosus, and Lactobacillus zeae) or to Lactobacillus fermentum induced high levels of IL-12. Phagocytosis of lactobacilli was necessary for IL-12 induction, and the strains with strong IL-12 induction were relatively resistant to lysis in the macrophages. The sensitivity of Lactobacillus strains to in vitro treatment with M-1 enzyme, a member of the N-acetylmuramidases, was negatively correlated with IL-12-inducing ability. Using a probiotic strain, L. casei strain Shirota (LcS), we showed that the cell wall of LcS could be digested by long-term treatment with a high dose of M-1 enzyme and that the IL-12-inducing ability was diminished according to the duration of the enzyme treatment. The soluble polysaccharide-peptidoglycan complex released from the cell wall of LcS did not induce IL-12, whereas the insoluble intact cell wall of LcS induced IL-12. These results suggest that the intact cell wall structure of lactobacilli is an important element in the ability to induce IL-12 and that Lactobacillus strains having a rigid cell wall resistant to intracellular digestion effectively stimulate macrophages to induce IL-12.

Animal models of rheumatoid arthritis and their relevance to human disease

Rodent models of rheumatoid arthritis (RA) are useful tools to study the pathogenic process of RA. Among the most widely used models of RA are the streptococcal cell wall (SCW) arthritis model and the collagen-induced arthritis (CIA). Both innate and adaptive immune mechanisms are involved in these rodent models. While no models perfectly duplicate the condition of human RA, they are easily reproducible, well defined and have proven useful for development of new therapies for arthritis, as exemplified by cytokine blockade therapies. Besides SCW and CIA models, there are numerous others including transgenic models such as K/BxN, induced models such as adjuvant-induced and pristane models, and spontaneous models in certain mouse strains, that have been used to help understand some of the underlying mechanisms. This review provides an update and analysis of RA models in mice and rats. The array of models has provided rheumatologists and immunologists a means to understand the multifactorial disease in humans, to identify new drug targets, and to test new therapies.

Chemokine secretion of rheumatoid arthritis synovial fibroblasts stimulated by Toll-like receptor 2 ligands

To analyze the role of Toll-like receptors (TLR) in the pathogenesis of rheumatoid arthritis, we have assessed the effects of stimulation of cultured synovial fibroblasts by the TLR-2 ligand bacterial peptidoglycan. By using high density oligonucleotide microarray analysis we identified 74 genes that were up-regulated >2.5-fold. Fourteen CC and CXC chemokine genes were among the genes with the highest up-regulation. Quantitative real-time PCR analysis confirmed up-regulation of granulocyte chemotactic protein (GCP)-2, RANTES, monocyte chemoattractant protein (MCP)-2, IL-8, growth-related oncogene-2, and to a lesser extent, macrophage-inflammatory protein 1alpha, MCP-1, EXODUS, and CXCL-16. GCP-2, RANTES, and MCP-2 were detected in culture supernatants of synovial fibroblasts stimulated with peptidoglycan. Chemokine secretion induced by stimulation of rheumatoid arthritis synovial fibroblasts via TLR-2 was functionally relevant as demonstrated by chemotaxis assays. GCP-2 and MCP-2 expression, which have not been reported previously in rheumatoid arthritis, was demonstrated in synovial tissue sections of patients diagnosed with rheumatoid arthritis but not in those with osteoarthritis. Correspondingly, synovial fluid levels were significantly higher in patients diagnosed with rheumatoid arthritis as compared with osteoarthritis. Thus, we present evidence for an induction of chemokine secretion by activation of synovial fibroblasts via TLR-2, possibly contributing to the formation of inflammatory infiltrates characteristically found in rheumatoid arthritis joints.

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.

Innate immunity in host-microbial interactions: beyond B27 in the spondyloarthropathies

The spondyloarthropathies are diseases influenced by genetic predisposition and, to a varying extent, infectious triggers. A causal role for bacterial infections is most clear for reactive arthritis. Recent insights into arthritogenic components of bacteria may set the stage for a better understanding of disease pathogenesis, the role of heat shock proteins in antigen processing and immune activation, and the adjuvant effect of CpG-DNA. Recent developments in the area of innate immunity broaden current concepts of genetically defined factors in host-pathogen interactions. In particular, the biology of toll-like receptors as important elements in the innate immune response to pathogens is being defined. These factors in innate immunity may have important implications for sequelae of infections, such as reactive arthritis.

Enzyme degradation and proinflammatory activity in arthritogenic and nonarthritogenic Eubacterium aerofaciens cell walls

Two almost-identical strains of Eubacterium aerofaciens isolated from the normal human gut flora were used. The cell wall (CW) of one strain with a peptidoglycan (PG) type A4alpha induces chronic arthritis in the rat after a single intraperitoneal injection, whereas CW of the other with PG type A4beta induces only a transient acute arthritis. The CW of the arthritogenic E. aerofaciens was a twofold-more-potent stimulator of the proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and monocyte chemoattractant protein 1 (MCP-1) than the nonarthritogenic CW. After degradation with mutanolysin, the capacity of the arthritogenic PG to stimulate production of TNF-alpha and MCP-1 was significantly increased, whereas that of the nonarthritogenic PG was significantly decreased. In other words, after enzyme degradation the arthritogenic PG had a four- to fivefold-stronger stimulatory capacity than that of the enzyme-treated nonarthritogenic PG. These findings indicate that the arthritogenicity of CW or a PG is not dependent on the enzyme resistance alone but also on how the PG fragments released by enzyme degradation stimulate the production of proinflammatory cytokines.

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.

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.