Effect of Mycobacterium vaccae on cytokine responses in children with atopic dermatitis

Mycobacterium vaccae immunization in rats ameliorates features of age-associated microglia activation in the amygdala and hippocampus

Aging and reduced exposure to environmental microbes can both potentiate neuroinflammatory responses. Prior studies indicate that immunization with the immunoregulatory and anti-inflammatory bacterium, Mycobacterium vaccae (M. vaccae), in aged rats limits neuroimmune activation and cognitive impairments. However, the mechanisms by which M. vaccae immunization ameliorates age-associated neuroinflammatory “priming” and whether microglia are a primary target remain unclear. Here, we investigated whether M. vaccae immunization protects against microglia morphological changes in response to aging. Adult (3 mos) and aged (24 mos) Fisher 344 × Brown Norway rats were immunized with either M. vaccae or vehicle once every week for 3 weeks. Aging led to elevated Iba1 immunoreactivity, microglial density, and deramification of microglia processes in the hippocampus and amygdala but not other brain regions. Additionally, aged rats exhibited larger microglial somas in the dorsal hippocampus, suggestive of a more activated phenotype. Notably, M. vaccae treatment ameliorated indicators of microglia activation in both the amygdala and hippocampus. While changes in morphology appeared to be region-specific, gene markers indicative of microglia activation were upregulated by age and lowered in response to M. vaccae in all brain regions evaluated. Taken together, these data suggest that peripheral immunization with M. vaccae quells markers of age-associated microglia activation.

Effects of immunization with heat-killed Mycobacterium vaccae on autism spectrum disorder-like behavior and epileptogenesis in a rat model of comorbid autism and epilepsy

Autism spectrum disorders (ASDs) and epilepsy are often comorbid. The basis for this co-occurrence remains unknown; however, inflammatory stressors during development are a shared risk factor. To explore this association, we tested the effect of repeated immunizations using a heat-killed preparation of the stress-protective immunoregulatory microbe Mycobacterium vaccae NCTC 11,659 (M. vaccae) on the behavioral and epileptogenic consequences of the combined stress-terbutaline (ST) rat model of ASD-like behavior/epilepsy. Repeated immunization of the dam with M. vaccae during pregnancy, followed by immunization of the pups after terbutaline injections, prevented the expression of ASD-like behavior but did not appear to protect against, and may have even enhanced, the spontaneous epileptogenic effects of ST. Maternal M. vaccae injections transferred an anti-inflammatory immunophenotype to offspring, and repeated injections across development prevented ST-induced increases in microglial density at early developmental time points in a region-specific manner. Despite epidemiological comorbidity between ASD/epileptic conditions and shared environmental risk factors, our results suggest that the expression of ASD-like behaviors, but perhaps not epileptogenesis, is sensitive to early anti-inflammatory intervention. These data provide support for the exploration of immunoregulatory strategies to prevent the negative neurodevelopmental behavioral effects of stressors during early critical periods.

Role of hygienic factors in the etiology of allergic disorders in children

BACKGROUND/AIM

We investigated the role of body flora and chronic inflammatory infections in the etiology of allergic disorders in Turkish children.

MATERIALS AND METHODS

Forty pediatric asthma patients with positive skin prick tests and 40 age-matched healthy subjects with negative skin prick tests were enrolled in this cross-sectional study. Serum H. pylori IgG, viral hepatitis serology, IL-10, and TGF-beta levels were measured. Stool and throat cultures were taken and tested for occurrence of microorganisms.

RESULTS

A significantly higher percentage of nonatopic subjects tested positive for anti-H. pylori antibodies compared to atopic subjects (60% vs. 20%). Serum IL-10 levels were also significantly higher in nonatopic subjects. No significant differences in direct microscopy and culture specimens of stools were observed. Examination of throat flora showed significantly higher occurrences of Neisseria and beta-hemolytic Streptococcus in nonatopic subjects, but higher occurrences of gram-positive bacilli in atopic subjects.

CONCLUSION

Higher prevalence of anti-H. pylori antibody and higher serum levels of IL-10 in nonatopic subjects suggest that chronic infection and inflammation may protect against atopic disease. Higher occurrences of Neisseria and beta-hemolytic Streptococcus in throat cultures from nonatopic subjects are novel findings that lend further support to the hygiene hypothesis.

Neonatal, atopic and infectious disease outcomes among children born to mothers with latent tuberculosis infection

Exposure to microbes may result in maternal immune responses that can affect fetal immune development. Several lines of evidence have shown that mycobacterial antigens can change the onset of atopic disease. We hypothesized that infants born to mothers with a positive tuberculosis (TB) test and a negative chest radiograph, may exhibit differential development of atopic disease during early childhood. The study was designed as a case control study. Birth records for infants born to untreated mothers with a positive TB skin test (TST), as defined by ≥10 mm induration were reviewed (n = 145 cases) and compared to a randomly selected unmatched control cohort of 46 women with a negative TST who delivered during the same time period at Scripps Hospital in San Diego, CA, USA. Childhood outcome parameters reviewed were: (1) the onset of physician diagnosed asthma; (2) lower respiratory tract infection (LRTI) with wheezing, latent tuberculosis infection/wheezing diagnosed on physical examination; (3) nonsurgical hospitalization; (4) atopic disease (eye/skin/nasal-sinus disease); (5) infections: ear, LRTI, sinus. LRTI was defined as an infection of the lower airways, eg, pneumonia. Outcomes at the end of years 1, 2, and 3–5 years combined were analyzed. Fisher exact test, Chi-square analysis or Poisson regression analysis were used as appropriate and a P-value of <0.05 was defined as significant. The cases and controls had similar birth weights, gestational ages, maternal ages: 3.34 versus 3.35 kg; 38.3 versus 39.2 weeks, 27.4 versus 26 years (P = non-significant). The childhood outcome parameters of the new onset of asthma was significantly higher than controls by age 2 years, but not at other ages studied, based on available clinic follow up data (P = 0.02). There was a difference in the risk for lung infection at age 2 and 3–5 years (P < 0.0001). There were no differences in the other outcome parameters studied (P = ns). There were no cases of infants with a positive TST, maternal Bacille Calmette-Guerin vaccination or active maternal TB, based on our study findings. There was a higher occurrence of asthma and lung infections at age 2 years among controls (P = 0.02). Our study defines for the first time a possible influence of maternal latent TB infection on fetal and childhood illness.

Complete genome sequence of Mycobacterium vaccae type strain ATCC 25954

Mycobacterium vaccae is a rapidly growing, nontuberculous Mycobacterium species that is generally not considered a human pathogen and is of major pharmaceutical interest as an immunotherapeutic agent. We report here the annotated genome sequence of the M. vaccae type strain, ATCC 25954.

The effects of Mycobacteria vaccae derivative on allergen-specific responses in children with atopic dermatitis

The capacity of microbial products to inhibit allergic inflammation make them logical candidates for novel therapies in allergic diseases such as atopic dermatitis. To assess the effects of intradermal Mycobacterium vaccae derivative on allergen-specific immune responses in children with moderate to severe atopic dermatitis. Peripheral blood mononuclear cells were isolated from children aged 5-16 years who received intradermal injections of M. vaccae derivative AVAC(TM) (n = 26) or placebo (n = 34) three times at 2-weekly intervals, weeks 0, 2 and 4. Cytokine [interleukin (IL)-13, interferon (IFN)-γ and IL-10] responses to allergen [house dust mite (HDM)], mitogen [phytohaemagglutinin (PHA)], Staphylococcal enterotoxin B (SEB) and Toll-like receptor (TLR) ligands were assessed. At week 8 (1 month after all injections given) children in the AVAC group showed a significant increase in IL-10 (P = 0·009), T helper type 1 (Th1) IFN-γ (P = 0·017) and Th2 IL-13 (P = 0·004) responses to HDM compared with baseline (week 0). There were no significant changes in any cytokine production in the placebo. HDM-specific IL-10 responses remained significantly higher (P = 0·014) than at baseline in the AVAC group by week 12; however, the HDM-specific IL-13 and IFN-γ responses were no longer significantly different from baseline. IL-13 (r = 0·46, P < 0·001) and IL-10 (r = 0·27, P = 0·044) responses to HDM were correlated with total immunoglobulin E but not with disease severity. There were no effects of AVAC on mitogen, SEB, TLR-2- or TLR-4-mediated responses. This M. vaccae derivative appeared to modulate responses to HDM selectively, suggesting the capacity for in vivo effects on allergen-specific immune responses.

An open study to assess the efficacy clinically and immunologically ofM. vaccaevaccine in patients with atopic dermatitis

OBJECTIVE

To assess clinical and immunological changes in a group of atopic dermatitis patients treated with Mycobacterium vaccae (M. vaccae).

METHODS

In an open, randomized, placebo-controlled, clinical observer-blinded trial, 20 patients with moderately severe to severe atopic dermatitis were treated with two subcutaneous M. vaccae injections 3 months apart. Clinical scoring and total serum IgE estimation were performed at the start, during and 3 months after the end of the study.

RESULTS

Modest clinical improvement was seen in the patients after M. vaccae immunotherapy. There was no significant change in patients' total serum IgE levels.

CONCLUSIONS

This study has shown limited improvement clinically in a group of patients with atopic dermatitis treated with two M. vaccae injections. It is suggested that further trials using four to six injections would produce much greater benefit.

Mycobacterium vaccae immunization to OVA sensitized pregnant BALB/c mice suppressed placental and postnatal IL-5 and inducing IFN-gamma secretion

Although the development of atopy in the newborn is determined by a multitude of factors, an intense Th1 stimulus early in life could be protective by facilitating a switch away from Th2. Aimed to determine the effect of single Mycobacterium vaccae (M. vaccae) immunization to OVA-sensitized pregnant mice on IL-5 and IFN-gamma secretion from placental lymphocytes and splenocytes of offspring. Pregnant BALB/c mice were divided into 4 groups, OVA-sensitized + M. vaccae immunized, OVA-sensitized, M. vaccae immunized and controls. Sensitization with OVA was initiated before mating, and aerosol OVA challenge were performed during pregnancy. M. vaccae immunization was performed on the 12(th) day of pregnancy. IL-5 and IFN-gamma levels of placental lymphocytes were analyzed on the 18(th) day of pregnancy and splenocytes of offspring on the 2(nd) and 28(th) days during postnatal period. A single administration of M. vaccae to OVA-sensitized pregnant mice downregulated IL-5 secretion and induced IFN-gamma secretion from placental lymphocytes. On the other hand, after M. vaccae immunization downregulation of IL-5 levels and upregulation of IFN-gamma secretion persisted in offspring when determined on 2(nd) and 28(th) days of life. Vaccination with M. Vaccae to OVA-sensitized pregnant BALB/c mice prevented Th2 immune responses by enhancing secretion of IFN-gamma and lowering IL-5 levels during pregnancy and the effect persisted during the postnatal period in offspring.

Mycobacteria and allergies

Exposure to mycobacteria was inevitable throughout mammalian evolution. Most mycobacteria are saprophytic environmental organisms that are enormously abundant in soil and untreated water and evoke immune responses in the residents of developing countries. A few species are pathogens. For example Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), infects approximately 1/3 of the world's population. Many individuals also receive vaccination with the Bacille Calmette Guérin (BCG), which is an attenuated form of the organism causing bovine TB. In order to understand the possible role that mycobacteria might have in the increases in allergic disorders over the last decades, it is necessary to dissect out these different mycobacterial influences. Above all it is essential, when analysing tuberculin test results, to distinguish between individuals who have latent TB and those who do not. Only then can probable effects of diverse types of exposure emerge. There is no doubt that in animal models mycobacteria can both prevent and treat allergic responses either by boosting Th1 or by driving allergen-specific regulatory T cells (RegT). Clinical trials in man remain inconclusive.

The production of a new extracellular putative long-chain saturated polyester by smooth variants of Mycobacterium vaccae interferes with Th1-cytokine production

Mycobacterium vaccae is of major pharmaceutical interest as an immunotherapeutic agent. Although M. vaccae 15483 ATCC(T) strain displays smooth and rough colonial morphologies on solid culture media, it is not known in which conditions M. vaccae switches from one colonial morphotype to the other or whether there are biological differences, especially immunological, between them. We have found that the change from a smooth to rough stable variant occurs spontaneously at 30 degrees C. The analysis of the composition of the cell wall in both variants showed that the smooth morphotype presents an extracellular material that has never previously been described and was identified as a long-chain saturated polyester that, interestingly, is not produced by the rough morphotype. Our results also indicate that this compound could be implicated in the spreading ability of smooth colonies. Proliferation, IFN-gamma and IL-12(p40) production by splenocyte cultures was significantly higher in mice immunised with the rough variant compared with those immunised with the smooth one. This latter finding suggests that the different colonial morphology of M. vaccae may affect the immunomodulatory effects induced from M. vaccae preparations.

Toll-like receptors—novel targets in allergic airway disease (probiotics, friends and relatives)

Experimental and epidemiological studies enabled to hypothesize that stimulation of the immune system by selected microbial products may prevent or treat allergic diseases. According to recent advances in molecular immunology, this stimulation acts via group of conserved receptors present on antigen presenting cells, known as toll-like receptors (TLRs). These receptors play an essential role in antigen presentation and latter development of immune response into pro-allergic (Th2), cellular (Th1) or regulatory (Tr1) responses. Since toll-like receptors govern decisive points in immune regulation, an extensive research focuses on agents interfering with their immunomodulatory activities. In this report, we review information on the potential use of microbial products in allergy prevention and therapy, which are believed to target toll-like receptor network. Current toll-like receptor-based approaches, as well as potential use of lipopolysaccharide (and derivates), oligonucleotides, mycobacteria, bacterial extracts, and probiotics are discussed herein.