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

Exploring the anti-inflammatory effects of postbiotic proteins from Lactobacillus delbrueckii CIDCA 133 on inflammatory bowel disease model

Lactobacillus delbrueckii CIDCA 133 is a promising health-promoting bacterium shown to alleviate intestinal inflammation. However, the specific bacterial components responsible for these effects remain largely unknown. Here, we demonstrated that consuming extractable proteins from the CIDCA 133 strain effectively relieved acute ulcerative colitis in mice. This postbiotic protein fraction reduced the disease activity index and prevented colon shortening in mice. Furthermore, histological analysis revealed colitis prevention with reduced inflammatory cell infiltration into the colon mucosa. Postbiotic consumption also induced an immunomodulatory profile in colitic mice, as evidenced by both mRNA transcript levels (Tlr2, Nfkb1, Nlpr3, Tnf, and Il6) and cytokines concentration (IL1β, TGFβ, and IL10). Additionally, it enhanced the levels of secretory IgA, upregulated the transcript levels of tight junction proteins (Hp and F11r), and improved paracellular intestinal permeability. More interestingly, the consumption of postbiotic proteins modulated the gut microbiota (Bacteroides, Arkkemansia, Dorea, and Oscillospira). Pearson correlation analysis indicated that IL10 and IL1β levels were positively associated with Bacteroides and Arkkemansia_Lactobacillus abundance. Our study reveals that CIDCA 133-derived proteins possess anti-inflammatory properties in colonic inflammation.

Maternal breast milk microbiota and immune markers in relation to subsequent development of celiac disease in offspring

The potential impact of the composition of maternal breast milk is poorly known in children who develop celiac disease (CD). The aim of our study was to compare the microbiota composition and the concentrations of immune markers in breast milk from mothers whose offspring carried the genetic predisposition to CD, and whether they did or did not develop CD during follow-up for the first 3 years of life. Maternal breast milk samples [CD children (n = 6) and healthy children (n = 18)] were collected 3 months after delivery. Enzyme-linked immunosorbent assays were used to measure TGF-β1, TGF-β2, sIgA, MFG-E8 and sCD14. For microbiota analysis, next generation (Illumina) sequencing, real-time PCR and denaturing gradient gel electrophoresis were used. Phylotype abundance and the Shannon ‘H’ diversity index were significantly higher in breast milk samples in the CD group. There was higher prevalence of the phyla Bacteroidetes and Fusobacteria, the classes Clostridia and Fusobacteriia, and the genera Leptotrichia, Anaerococcus, Sphingomonas, Actynomyces and Akkermansia in the CD group. The immunological markers were differently associated with some Gram-negative bacterial genera and species (Chryseobacterium, Sphingobium) as well as Gram-positive species (Lactobacillusreuteri, Bifidobacteriumanimalis). In conclusion, the microbiota in breast milk from mothers of genetically predisposed offspring who presented CD showed a higher bacterial phylotype abundance and diversity, as well as a different bacterial composition, as compared with the mothers of unaffected offspring. These immune markers showed some associations with bacterial composition and may influence the risk for development of CD beyond early childhood.

Identification of common vaginal Lactobacilli immunoreactive proteins by immunoproteomic techniques

Lactobacilli are considered as the most important microorganisms in regulating immune system and maintaining vaginal health. The uses and benefits of Lactobacilli as probiotics, particularly the regulation of immune system, are dependent on the strain used and a comprehensive understanding of their effects on the host. Several factors have been identified in Lactobacilli that influence the immune response, such as exopolysaccharides and proteins. The current study was designed to investigate the serum immunoreactivity of healthy women against common vaginal Lactobacilli immunoreactive proteins. Three common vaginal Lactobacillus strains (L. crispatus L1, L. gasseri L9, and L. fermentum L2) were compared for immune response. The ELISA results showed that the levels of total immunoglobulin (Ig-total) antibody for L. crispatus L1, L. fermentum L2, and L. gasseri L9 were 47%, 45% and 29%, respectively. Regarding the lower prevalence of L. fermentum L2 in comparison with the other two strains, the approximately equal levels of Ig-total compared to L. crispatus L1 and more than L. gasseri L9 indicate that L. fermentum L2 has the greater antigenicity ability. Accordingly, the immunoreactive proteins of L. fermentum L2 were identified using MALDI-TOF-MS detected by SDS-PAGE and Western blotting. These proteins included 30s ribosomal protein S4 and 50s ribosomal protein L5. Antigenic epitopes on the 3D structure of these proteins was also predicted using bioinformatics analysis. The presence of antibody in serum of healthy pre-menopausal women indicates that Lactobacilli (normal flora) proteins can stimulate host immune response. Purification and further studies of the proteins may allow their potential use as an adjuvant to improve the efficacy of vaccines.

Identification of Lactobacillus proteins with different recognition patterns between immune rabbit sera and nonimmune mice or human sera

Background

The genus Lactobacillus belongs to a large heterogeneous group of low G + C Gram-positive anaerobic bacteria, which are frequently used as probiotics. The health-beneficial effects, in particular the immunomodulation effect, of probiotics depend on the strain and dose used. Strain variations may be related to diversity of the cell surface architecture of bacteria and the ability to express specific antigens or secrete compounds. The use of Lactobacillus as probiotic requires a comprehensive understanding of its effect on host immune system. To evaluate the potential immunoreactive properties of proteins isolated from four Lactobacillus strains: L. johnsonii 142 and L. johnsonii 151, L. rhamnosus LOCK 0900 and L. casei LOCK 0919, the polyclonal sera obtained from mouse and human have been tested as well as with sera from rabbits immunized with whole lactobacilli cells.

Results

The reactivity of isolated proteins detected by SDS-PAGE and Western blotting was heterogeneous and varied between different serum samples. The proteins with the highest immunoreactivity were isolated, purified and sequenced, in particular the fractions were identified as phosphoglycerate kinase (L. johnsonii 142), glyceraldehyde 3-phosphate dehydrogenase (L. johnosnii 142, L. rhamnosus LOCK 0900), hypothetic protein JDM1_1307 (L. johnsonii 151) and fructose/tagatose-bisphosphate-aldolase (L. casei LOCK 0919).

Conclusion

The different prevalence of reactions against tested antigens in rabbit, mouse and human sera may indicate significant differences in immune system and commensal cross-talk in these groups. The identification of immunoreactive lactobacilli proteins opens the possibility to use them as an antigens for development of vaccines.

A functional analysis of the formyl-coenzyme A (frc) gene from Lactobacillus reuteri 100-23C

AIM

To examine the role of the Lactobacillus reuteri 100-23C frc gene product in oxalate metabolism, host colonization and the acid stress response.

METHODS AND RESULTS

Genes encoding putative formyl-CoA transferase (frc) and oxalyl-CoA decarboxylase (oxc) enzymes are present in the genome sequences of Lact. reuteri strains. Two strains isolated from humans harboured an IS200 insertion sequence in the frc ORF and a group 2 intron-associated transposase downstream of the frc gene, both of which were lacking in two strains of animal origin, which contained intact frc and oxc genes. An frc(-) insertional mutant of Lact. reuteri 100-23C was compared with the parent strain with respect to oxalate degradation, colonization of an RLF-mouse host model and growth in the presence of acids. Neither parent nor mutant degraded oxalate in vitro or in vivo. However, the parent outcompeted the frc(-) mutant in the mouse intestine during co-colonization and the frc(-) mutant showed a reduced growth rate in the presence of hydrochloric acid.

CONCLUSIONS

Intact oxc and frc genes do not ensure oxalate degradation under the conditions tested. The frc gene product is important during host colonization and survival of acid stress by Lact. reuteri 100-23C.

SIGNIFICANCE AND IMPACT OF THE STUDY

Oxalate metabolism by oxalate-degrading intestinal bacterial strains may be important in preventing urolithiasis and might lead to the derivation of probiotic products. To produce safe and efficacious probiotics, however, an understanding of the genetic characteristics of potential oxalate degraders must be obtained, together with knowledge of their functional ramifications.

Antibodies to Lactobacilli and Bifidobacteria in young children with different propensity to develop islet autoimmunity

The intestinal microbiota is essential to the maturation and homeostasis of the immune system. Immunoblot assays were used to establish the prevalence of serum IgG, IgM, and IgA antibodies specific for Bifidobacterium adolescentis, Bifidobacterium longum, and Lactobacillus rhamnosus GG proteins in young children presenting with or without type 1 diabetes (T1D). We demonstrated that children between the ages of 6 and 12 months had a substantial increase in the frequency of IgG antibodies specific for L. rhamnosus GG proteins. We measured IgG, IgM, and IgA class antibody reactivity against B. adolescentis DSM 20083, B. adolescentis DSM 20086, and B. longum DSM 20088 proteins demonstrating significantly higher IgA responses against B. adolescentis DSM 20083 strain proteins in children who developed islet autoimmunity and T1D later in life. B. adolescentis strains showed more IgM type antibodies in children who developed T1D later in life, but the difference was not statistically significant. B. longum proteins were recognized by IgG and IgA antibodies to a higher extent compared to other bacteria studied. These results confirm that differences in immune reactivity against some commensal strains in young children may represent a different risk factor for developing T1D.

Metabiotics: novel idea or natural development of probiotic conception

Traditionally, probiotics on the base of live microorganisms are considered to be both beneficial and safe. Unfortunately, their effects may have short-term success or are absent or uncertain. Some symbiotic (probiotic) microorganisms with known beneficial health affects may cause opportunistic infections, increase incidence of allergic sensitization and autoimmune disorders, produce microecological imbalance, modify gene expression, transfer antibiotic resistant and virulence genes, cause disorders in epigenome and genome integrity, induce chromosomal DNA damage, and activate signaling pathways associated with cancer and other chronic diseases. The commercially available probiotics should be considered as a first generation means of correcting microecological disorders. Further, their development will include the selection of natural metabiotics and/or working out the synthetic (or semi-synthetic) metabiotics that will be analogies or improved copies of natural bioactives, produced by symbiotic (probiotic) microorganisms. Metabiotics are the structural components of probiotic microorganisms and/or their metabolites and/or signaling molecules with a determined (known) chemical structure that can optimize host-specific physiological functions, regulator, metabolic and/or behavior reactions connected with the activity of host indigenous microbiota. Metabiotics have some advantages because of their exact chemical structure, well dosed, very safe and long shelf-life. Thus, now metabiotics should not consider myth; they are the result of the natural evolution of probiotic conception.

Celiac disease in patients with type 1 diabetes: a condition with distinct changes in intestinal immunity?

Two common chronic childhood diseases-celiac disease (CD) and type 1 diabetes (T1D)-result from complex pathological mechanisms where genetic susceptibility, environmental exposure, alterations in intestinal permeability and immune responses play central roles. In this study, we investigated whether these characteristics were universal for CD independently of T1D association. For this purpose, we studied 36 children with normal small-bowel mucosa and 26 children with active CD, including 12 patients with T1D. In samples from the small-bowel mucosa, we detected the lowest expression of tight junction protein 1 (TJP1) mRNA in CD patients with T1D, indicating an increase in intestinal permeability. Furthermore, these samples displayed the highest expression of forkhead box P3 (FoxP3) mRNA, a marker for regulatory T cells, as compared with other patient groups. At the same time, serum levels of IgA antibodies specific for the CD-related antigens deamidated gliadin and tissue transglutaminase (tTG) were the highest in CD patients with T1D. In contrast, no significant differences were found in IgA or IgG antibodies specific for bovine beta-lactoglobulin or Bifidobacterium adolescentis DSM 20083-derived proteins. There were also no differences in the transamidating activity of serum autoantibodies between patients and control individuals. Our results show that patients with T1D and newly detected CD exhibit severely altered intestinal permeability, strong local immune activation and increased immunoregulatory mechanisms in the small bowel. Further study is required to determine whether these extreme changes in this CD subgroup are due to some specific environmental factors (virus infections), unknown genetic effects or autoimmune reactions to antigenic targets in intracellular tight junctions.

Gut microbial gene expression in mother-fed and formula-fed piglets

BACKGROUND

Effects of diet on the structure and function of gut microbial communities in newborn infants are poorly understood. High-resolution molecular studies are needed to definitively ascertain whether gut microbial communities are distinct in milk-fed and formula-fed infants.

METHODOLOGY/PRINCIPAL FINDINGS

Pyrosequencing-based whole transcriptome shotgun sequencing (RNA-seq) was used to evaluate community wide gut microbial gene expression in 21 day old neonatal piglets fed either with sow's milk (mother fed, MF; n = 4) or with artificial formula (formula fed, FF; n = 4). Microbial DNA and RNA were harvested from cecal contents for each animal. cDNA libraries and 16S rDNA amplicons were sequenced on the Roche 454 GS-FLX Titanium system. Communities were similar at the level of phylum but were dissimilar at the level of genus; Prevotella was the dominant genus within MF samples and Bacteroides was most abundant within FF samples. Screened cDNA sequences were assigned functional annotations by the MG-RAST annotation pipeline and based upon best-BLASTX-hits to the NCBI COG database. Patterns of gene expression were very similar in MF and FF animals. All samples were enriched with transcripts encoding enzymes for carbohydrate and protein metabolism, as well as proteins involved in stress response, binding to host epithelium, and lipopolysaccharide metabolism. Carbohydrate utilization transcripts were generally similar in both groups. The abundance of enzymes involved in several pathways related to amino acid metabolism (e.g., arginine metabolism) and oxidative stress response differed in MF and FF animals.

CONCLUSIONS/SIGNIFICANCE

Abundant transcripts identified in this study likely contribute to a core microbial metatranscriptome in the distal intestine. Although microbial community gene expression was generally similar in the cecal contents of MF and FF neonatal piglets, several differentially abundant gene clusters were identified. Further investigations of gut microbial gene expression will contribute to a better understanding of normal and abnormal enteric microbiology in animals and humans.