Intradermal injection of heat-killed Mycobacterium vaccae in dogs with atopic dermatitis: a multicentre pilot study

Intradermal immunotherapy with actinomycetales preparations as treatment for feline atopic syndrome: a randomized, placebo-controlled, double-blinded study

BACKGROUND

Feline atopic syndrome (FAS) is a common disease. Single intradermal injections of heat-killed actinomycetales have shown beneficial effects in canine allergies.

HYPOTHESIS/OBJECTIVE

To evaluate the clinical effects of heat-killed actinomycetales [Gordonia bronchialis (GB) and Rodococcus coprophilus (RC)], alone or in combination, in FAS.

METHODS AND MATERIALS

Privately owned cats with a diagnosis of FAS were assigned randomly in three treatment groups (GB, RC and GB/RC combination) or placebo. Five intradermal injections were performed over a one year period. At each visit [Day (D)0, D20, D40, D60, D90, D180 and D365], clinical signs, global owner assessment score, use of rescue medications, clinical adverse effects, skin hydration and cutaneous pH were assessed.

RESULTS

Seventeen cats were enrolled. When compared to the placebo group and improvement in treatment GB was sustained from D90. When compared with D0 significant improvement in the GB group was seen from D60. Over one year, a complete remission of the clinical signs was seen in 30-67% of cats in the treatment groups. A reduction in the pruritus score was seen for RC after 365 days of treatment (P = 0.04). Differences in the other variables were not seen.

CONCLUSIONS AND CLINICAL IMPORTANCE

The use of multiple intradermal injections of heat-killed GB shows promise as effective and well-tolerated treatment for FAS. Because of the low cost and the lack of adverse effects, GB could be a beneficial treatment option for FAS. A larger study is needed to confirm these data and to evaluate the immunological changes occurring in the treated cats.

Identification and characterization of a novel anti-inflammatory lipid isolated from Mycobacterium vaccae, a soil-derived bacterium with immunoregulatory and stress resilience properties

RATIONALE

Mycobacterium vaccae (NCTC 11659) is an environmental saprophytic bacterium with anti-inflammatory, immunoregulatory, and stress resilience properties. Previous studies have shown that whole, heat-killed preparations of M. vaccae prevent allergic airway inflammation in a murine model of allergic asthma. Recent studies also demonstrate that immunization with M. vaccae prevents stress-induced exaggeration of proinflammatory cytokine secretion from mesenteric lymph node cells stimulated ex vivo, prevents stress-induced exaggeration of chemically induced colitis in a model of inflammatory bowel disease, and prevents stress-induced anxiety-like defensive behavioral responses. Furthermore, immunization with M. vaccae induces anti-inflammatory responses in the brain and prevents stress-induced exaggeration of microglial priming. However, the molecular mechanisms underlying anti-inflammatory effects of M. vaccae are not known.

OBJECTIVES

Our objective was to identify and characterize novel anti-inflammatory molecules from M. vaccae NCTC 11659.

METHODS

We have purified and identified a unique anti-inflammatory triglyceride, 1,2,3-tri [Z-10-hexadecenoyl] glycerol, from M. vaccae and evaluated its effects in freshly isolated murine peritoneal macrophages.

RESULTS

The free fatty acid form of 1,2,3-tri [Z-10-hexadecenoyl] glycerol, 10(Z)-hexadecenoic acid, decreased lipopolysaccharide-stimulated secretion of the proinflammatory cytokine IL-6 ex vivo. Meanwhile, next-generation RNA sequencing revealed that pretreatment with 10(Z)-hexadecenoic acid upregulated genes associated with peroxisome proliferator-activated receptor alpha (PPARα) signaling in lipopolysaccharide-stimulated macrophages, in association with a broad transcriptional repression of inflammatory markers. We confirmed using luciferase-based transfection assays that 10(Z)-hexadecenoic acid activated PPARα signaling, but not PPARγ, PPARδ, or retinoic acid receptor (RAR) α signaling. The effects of 10(Z)-hexadecenoic acid on lipopolysaccharide-stimulated secretion of IL-6 were prevented by PPARα antagonists and absent in PPARα-deficient mice.

CONCLUSION

Future studies should evaluate the effects of 10(Z)-hexadecenoic acid on stress-induced exaggeration of peripheral inflammatory signaling, central neuroinflammatory signaling, and anxiety- and fear-related defensive behavioral responses.

Therapies in Canine Atopic Dermatitis: An Update

Canine atopic dermatitis (AD) is one of the most common inflammatory skin diseases in dogs. The pathogenesis is complex and not completely understood. Many therapeutic options are available; however, because of cost, side effects, or a long lag phase, new compounds are constantly produced. This article provides a comprehensive review of the latest compounds for the treatment of canine AD. In addition, a brief review of new studies on conventional medications is provided. For a successful long-term therapeutic approach, it is important to considerate the status of the disease, as well as the patients' and their owners' needs.

Hygiene hypothesis and autoimmune diseases

Throughout the twentieth century, there were striking increases in the incidences of many chronic inflammatory disorders in the rich developed countries. These included autoimmune disorders such as Type 1 diabetes and multiple sclerosis. Although genetics and specific triggering mechanisms such as molecular mimicry and viruses are likely to be involved, the increases have been so rapid that any explanation that omits environmental change is incomplete. This chapter suggests that a series of environmental factors, most of them microbial, have led to a decrease in the efficiency of our immunoregulatory mechanisms because we are in a state of evolved dependence on organisms with which we co-evolved (and that had to be tolerated) as inducers of immunoregulatory circuits. These organisms ("Old Friends") are depleted from the modern urban environment. Rather than considering fetal programming by maternal microbial exposures, neonatal programming, the hygiene hypothesis, gut microbiota, and diet as separate and competing hypotheses, I attempt here to integrate these ideas under a single umbrella concept that can provide the missing immunoregulatory environmental factor that is needed to explain the recent increases in autoimmune disease.

Successful immunotherapy of canine flea allergy with injected Actinomycetales preparations

AIMS

Can heat-killed, borate-buffered suspensions of Gordonia bronchialis, Rhodococcus coprophilus or Tsukamurella inchonensis be used to treat canine flea allergy?

MATERIALS & METHODS

Organisms cultured on Sauton's medium into stationary phase were autoclaved in borate-buffered saline and stored at 10 mg wet weight/ml. Intradermal injections of 0.1 ml containing 1 mg of bacilli were administered on the first and 20th days of the study. G. bronchialis and R. coprophilus were most effective in a pilot study of a small number of dogs with flea allergy. A larger number of affected dogs were then randomized to receive placebo or either of the two selected reagents. The extent and severity of allergic signs and symptoms were scored and blood samples were collected just before the first injection and 28 days after the second.

RESULTS

Both selected reagents reduced the extent and severity of lesions (p < 0.001) and reduced scratching. Eosinophil numbers were reduced (p < 0.0001) between the first and second assessment.

CONCLUSIONS

Injections of G. bronchialis or R. coprophilus effectively reduce the signs and symptoms of flea allergy in dogs.

DC priming by M. vaccae inhibits Th2 responses in contrast to specific TLR2 priming and is associated with selective activation of the CREB pathway

The environmental mycobacterium, M. vaccae has been used in mouse models to support the contemporary hygiene hypothesis that non-pathogenic microorganisms reduce allergy associated T helper (Th)2 responses and inflammatory diseases by augmenting regulatory T cells. However, data for human models and possible mechanisms are limited. We tested the effect of innate immune interactions between human DC and M. vaccae on DC-dependent T cell responses. M. vaccae activation of DC via Toll like receptor (TLR)2 was compared to a specific TLR2 ligand (Pam(3)CSK4) and alternative stimulation with a TLR4 ligand (LPS). M. vaccae induced DC dependent inhibition of Th2 responses, in contrast to Pam(3)CSK4, which had the opposite effect and LPS, which had no polarizing effect. DC maturation, gene expression and cytokine production, in response to each stimulus did not correlate with the specific functional effects. Comparable DC transcriptional responses to M. vaccae and Pam(3)CSK4 suggested that TLR2 mediated transcriptional regulation was not sufficient for inhibition of Th2 responses. Transcription factor enrichment analysis and assessment of signaling events, implicated a role for selective early activation of the CREB pathway by M. vaccae. Further study of the CREB pathway may provide novel insight into the molecular mechanisms of DC-dependent T cell polarization.

Inflammation, sanitation, and consternation: loss of contact with coevolved, tolerogenic microorganisms and the pathophysiology and treatment of major depression

CONTEXT

Inflammation is increasingly recognized as contributing to the pathogenesis of major depressive disorder (MDD), even in individuals who are otherwise medically healthy. Most studies in search of sources for this increased inflammation have focused on factors such as psychosocial stress and obesity that are known to activate inflammatory processes and increase the risk for depression. However, MDD may be so prevalent in the modern world not just because proinflammatory factors are widespread, but also because we have lost contact with previously available sources of anti-inflammatory, immunoregulatory signaling.

OBJECTIVE

To examine evidence that disruptions in coevolved relationships with a variety of tolerogenic microorganisms that were previously ubiquitous in soil, food, and the gut, but that are largely missing from industrialized societies, may contribute to increasing rates of MDD in the modern world.

DATA SOURCES

Relevant studies were identified using PubMed and Ovid MEDLINE.

STUDY SELECTION

Included were laboratory animal and human studies relevant to immune functioning, the hygiene hypothesis, and major depressive disorder identified via PubMed and Ovid MEDLINE searches.

DATA EXTRACTION

Studies were reviewed by all authors, and data considered to be potentially relevant to the contribution of hygiene-related immune variables to major depressive disorder were extracted.

DATA SYNTHESIS

Significant data suggest that a variety of microorganisms (frequently referred to as the "old friends") were tasked by coevolutionary processes with training the human immune system to tolerate a wide array of non-threatening but potentially proinflammatory stimuli. Lacking such immune training, vulnerable individuals in the modern world are at significantly increased risk of mounting inappropriate inflammatory attacks on harmless environmental antigens (leading to asthma), benign food contents and commensals in the gut (leading to inflammatory bowel disease), or self-antigens (leading to any of a host of autoimmune diseases). Loss of exposure to the old friends may promote MDD by increasing background levels of depressogenic cytokines and may predispose vulnerable individuals in industrialized societies to mount inappropriately aggressive inflammatory responses to psychosocial stressors, again leading to increased rates of depression.

CONCLUSION

Measured exposure to the old friends or their antigens may offer promise for the prevention and treatment of MDD in modern industrialized societies.

Gender and the hygiene hypothesis

The hygiene hypothesis offers an explanation for the correlation, well-established in the industrialized nations of North and West, between increased hygiene and sanitation, and increased rates of asthma and allergies. Recent studies have added to the scope of the hypothesis, showing a link between decreased exposure to certain bacteria and parasitic worms, and increased rates of depression and intestinal auto-immune disorders, respectively. What remains less often discussed in the research on these links is that women have higher rates than men of asthma and allergies, as well as many auto-immune disorders, and also depression. The current paper introduces a feminist understanding of gender socialization to the epidemiological and immunological picture. That standards of cleanliness are generally higher for girls than boys, especially under the age of five when children are more likely to be under close adult supervision, is a robust phenomenon in industrialized nations, and some research points to a cross-cultural pattern. I conclude that, insofar as the hygiene hypothesis successfully identifies standards of hygiene and sanitation as mediators of immune health, then attention to the relevant patterns of gender socialization is important. The review also makes clear that adding a feminist analysis of gender socialization to the hygiene hypothesis helps explain variation in morbidity rates not addressed by other sources and responds to a number of outstanding puzzles in current research. Alternative explanations for the sex differences in the relevant morbidity rates are also discussed (e.g., the effects of estrogens). Finally, new sources of evidence for the hygiene hypothesis are suggested in the form of cross-cultural and other natural experiments.

Review series on helminths, immune modulation and the hygiene hypothesis: the broader implications of the hygiene hypothesis

Man has moved rapidly from the hunter-gatherer environment to the living conditions of the rich industrialized countries. The hygiene hypothesis suggests that the resulting changed and reduced pattern of exposure to microorganisms has led to disordered regulation of the immune system, and hence to increases in certain inflammatory disorders. The concept began with the allergic disorders, but there are now good reasons for extending it to autoimmunity, inflammatory bowel disease, neuroinflammatory disorders, atherosclerosis, depression associated with raised inflammatory cytokines, and some cancers. This review discusses these possibilities in the context of Darwinian medicine, which uses knowledge of evolution to cast light on human diseases. The Darwinian approach enables one to correctly identify some of the organisms that are important for the 'Hygiene' or 'Old Friends' hypothesis, and to point to the potential exploitation of these organisms or their components in novel types of prophylaxis with applications in several branches of medicine.

Orally administered Mycobacterium vaccae modulates expression of immunoregulatory molecules in BALB/c mice with pulmonary tuberculosis

The environmental saprophyte Mycobacterium vaccae induces a Th1 response and cytotoxic T cells that recognize M. tuberculosis, and by subcutaneous injection, it is therapeutic for pulmonary tuberculosis (TB) induced by high-dose challenge in BALB/c mice. However, M. vaccae also drives regulatory T cells that inhibit Th2 responses, and this is seen in allergy models, not only following subcutaneous injection but also after oral administration. An oral immunotherapeutic for TB would be clinically useful, so we investigated M. vaccae given orally by gavage at 28-day intervals in the TB model. We used two different protocols: starting the oral M. vaccae either 1 day before or 32 days after infection with M. tuberculosis. Throughout the infection (until 120 days), we monitored outcome (CFU), molecules involved in the development of immunoregulation (Foxp3, hemoxygenase 1, idoleamine 2,3-dioxygenase, and transforming growth factor beta [TGF-beta]), and indicators of cytokine balance (tumor necrosis factor, inducible nitric oxide synthase, interleukin-4 [IL-4], and IL-4delta2; an inhibitory splice variant of IL-4 associated with improved outcome in human TB). Oral M. vaccae had a significant effect on CFU and led to increased expression of Th1 markers and of IL-4delta2, while suppressing IL-4, Foxp3, and TGF-beta. When administered 1 day before infection, oral M. vaccae induced a striking peak of expression of hemoxygenase 1. In conclusion, we show novel information about the expression in TB of murine IL-4delta2 and molecules involved in immunoregulation and show that these can be modulated by oral administration of a saprophytic mycobacterium. A clinical trial of oral M. vaccae in extensively drug-resistant TB might be justified.

The changing microbial environment and chronic inflammatory disorders

: There is much to be gained from examining human diseases within the expanding framework of Darwinian medicine. This is particularly true of those conditions that change in frequency as populations develop from the human "environment of evolutionary adaptedness" to the living conditions of the rich industrialized countries. This development entails major changes in lifestyle, leading to reductions in contact with environmental microorganisms and helminths that have evolved a physiologic role as drivers of immunoregulatory circuits. It is suggested that a deficit in immunoregulation in rich countries is contributing not only to increases in the incidence of allergic disorders but also to increases in other chronic inflammatory conditions that are exacerbated by a failure to terminate inappropriate inflammatory reponses. These include autoimmunity, neuroinflammatory disorders, atherosclerosis, depression associated with raised inflammatory cytokines, and some cancers.

Intradermal injection of Hsp60 induces cytokine responses in canine atopic and healthy skin

The purpose of this study was to investigate the immunoregulatory potential of Hsp60 in the skin of dogs with atopic dermatitis. Three dogs with chronic atopic dermatitis and four healthy dogs were injected intradermally with Hsp60 and phosphate-buffered saline. Biopsies were taken before testing from non-injected control skin, lesional and non-lesional atopic skin, and 48 and 72 h after injection. Analysis of cytokine messenger RNA was performed using quantitative real-time polymerase chain reaction. Forty-eight hours after Hsp60 injection, a rise in interleukin (IL)-10 was found (P = 0.034) with the highest expression levels in non-lesional atopic and control skin. A rise of transforming growth factor beta (P = 0.015) and IL-12p40 (P = 0.017) was noticed 72 h after Hsp60 injection in control skin. No significant differences were observed for the expression of IL-4, IL-12p35, and interferon gamma. The results indicate that Hsp60 is able to induce cytokines of a regulatory and Th1 phenotype in the skin. Furthermore, this study seems to provide a first indication of deficient Hsp60 response in atopic dermatitis affected skin.

The hygiene hypothesis and psychiatric disorders

The hygiene hypothesis proposes that several chronic inflammatory disorders (allergies, autoimmunity, inflammatory bowel disease) are increasing in prevalence in developed countries because a changing microbial environment has perturbed immunoregulatory circuits which normally terminate inflammatory responses. Some stress-related psychiatric disorders, particularly depression and anxiety, are associated with markers of ongoing inflammation, even without any accompanying inflammatory disorder. Moreover, pro-inflammatory cytokines can induce depression, which is commonly seen in patients treated with interleukin-2 or interferon-alpha. Therefore, some psychiatric disorders in developed countries might be attributable to failure of immunoregulatory circuits to terminate ongoing inflammatory responses. This is discussed in relation to the effects of the immune system on a specific group of brain serotonergic neurons involved in the pathophysiology of mood disorders.

The hygiene hypothesis and the increasing prevalence of chronic inflammatory disorders

The 'Hygiene' or 'Old Friends' hypothesis suggests that increases in chronic inflammatory disorders (allergies, inflammatory bowel disease and autoimmunity) in developed countries are partly attributable to diminishing exposure to organisms that were part of mammalian evolutionary history. Crucial organisms, including helminths and saprophytic mycobacteria, are recognised by the innate immune system as harmless or, in the case of helminths, as organisms that once established must be tolerated. This recognition then triggers development of regulatory dendritic cells that drive regulatory T-cell responses to the 'Old Friends' themselves and to simultaneously processed 'forbidden' target antigens of the chronic inflammatory disorders.