Immunomodulation: the future cure for allergic diseases

The Foetal Origins of Allergy and Potential Nutritional Interventions to Prevent Disease

The first nine months from conception to birth involves greater changes than at any other time in life, affecting organogenesis, endocrine, metabolic and immune programming. It has led to the concept that the “first 1000 days” from conception to the second birthday are critical in establishing long term health or susceptibility to disease. Immune ontogeny is predominantly complete within that time and is influenced by the maternal genome, health, diet and environment pre-conception and during pregnancy and lactation. Components of the immunological protection of the pregnancy is the generation of Th-2 and T-regulatory cytokines with the consequence that neonatal adaptive responses are also biased towards Th-2 (allergy promoting) and T-regulatory (tolerance promoting) responses. Normally after birth Th-1 activity increases while Th-2 down-regulates and the evolving normal human microbiome likely plays a key role. This in turn will have been affected by maternal health, diet, exposure to antibiotics, mode of delivery, and breast or cow milk formula feeding. Complex gene/environment interactions affect outcomes. Many individual nutrients affect immune mechanisms and variations in levels have been associated with susceptibility to allergic disease. However, intervention trials employing single nutrient supplementation to prevent allergic disease have not achieved the expected outcomes suggested by observational studies. Investigation of overall dietary practices including fresh fruit and vegetables, fish, olive oil, lower meat intake and home cooked foods as seen in the Mediterranean and other healthy diets have been associated with reduced prevalence of allergic disease. This suggests that the “soup” of overall nutrition is more important than individual nutrients and requires further investigation both during pregnancy and after the infant has been weaned. Amongst all the potential factors affecting allergy outcomes, modification of maternal and infant nutrition and the microbiome are easier to employ than changing other aspects of the environment but require large controlled trials before recommending changes to current practice.

Dose-response relationship of specific allergen exposure-induced immunological tolerance: a mouse model

BACKGROUND

It is believed that adequate allergen preimmunization exposure could induce immunologic tolerance. The purpose of this study was to investigate the dose-dependent mechanisms related to antigen-specific tolerance induction in a mouse model.

METHODS

Mice were assigned to 5 groups: the control (Cont) group received phosphate-buffered saline (PBS) preimmunization exposure and PBS sham immunization; the other 4 groups were exposed preimmunization to PBS (PBS group) or ovalbumin (OVA) (first mucosal doses: 1.25%, 2.5%, or 5% wt/vol aerosol from days -3 to -1) prior to OVA immunization. The OVA-immunized mice received intraperitoneal doses of 20 μg OVA (on days 1, 7, and 14), and then a second set of mucosal doses with 0.5% wt/vol OVA aerosol (on days 18 to 20). After assessment of airway hyperresponsiveness (AHR), the mice were euthanized and their blood, bronchoalveolar lavage fluids (BALFs), and lung tissues were collected for further analyses.

RESULTS

OVA-immunized mice exposed to OVA preimmunization had reduced AHR and immunoglobulin E production when compared to the PBS group. OVA preimmunization exposure inhibited eosinophilic inflammation in lung tissues. The proportions of BALF eosinophil counts from the groups exposed to OVA preimmunization were significantly decreased when compared with those exposed to PBS preimmunization. The balance of T helper 2 (Th2) and T regulatory (Treg) cytokines in BALFs were additionally observed in this mouse model.

CONCLUSION

Our results suggest that preimmunization exposure to an appropriate dose of a specific antigen could suppress allergic airway inflammation by induction of immunological tolerance.

Allergen-specific immunotherapy in food anaphylaxis

Specific immunotherapy (SIT) protocols for nutritional allergens have only recently been established with a focus on oral allergy syndrome because of pollen cross-reacting antibodies. For these patients, a substantial number of studies have been published suggesting benefits from SIT. The situation in true anaphylaxis to food allergens such as peanut allergy is more complex, and therapeutic strategies are based on individual protocols rather than controlled studies. However, in defined cases, SIT represents a promising approach for a durable protection from life-threatening risks after accidental ingestion.

Safety immunopharmacology: evaluation of the adverse potential of pharmaceuticals on the immune system

The ICH S6R1 and S8 guidelines define a general framework for the immunotoxicity evaluation of biotechnology-derived pharmaceuticals and human pharmaceuticals, respectively. As severe and unpredicted adverse events dramatically showed in the recent years that the immune system is a critical aspect of drug safety, this framework needs to be revisited to enhance the prediction of nonclinical immune safety evaluation. Safety immunopharmacology is deemed to contribute to this awaited improvement by enabling early screening of the potential for drug candidates to induce unexpected immunosuppressive and immunostimulatory effects as well as nonimmune-mediated hypersensitivity reactions. Dedicated safety immunopharmacology can also generate mechanistic data to determine which relevant additional immunotoxicity studies should be conducted. Immunological assays and models that can be considered for use in the context of safety pharmacology studies are presented as well as perspectives for their timely development.

Modular antigen-translocation as a novel vaccine strategy for allergen-specific immunotherapy

PURPOSE OF REVIEW

The purpose of the present review is to describe recent approaches aimed at improving the treatment of allergic diseases through allergen-specific immunotherapy (SIT). Special emphasis will be given to the approach based on specific targeting of the major histocompatibility complex (MHC) class-II antigen-presentation pathway.

RECENT FINDINGS

It is well recognized that IgE-mediated allergic diseases including rhinitis, atopic eczema and allergic asthma are increasing worldwide to a pandemic dimension. The only curative treatment remains allergen-SIT, which, however, requires a long treatment time of 3-5 years with up to 80 injections to confer protection. Recent findings strongly indicate that the treatment time and the number of injections could be drastically reduced by turning immunotherapy to a true vaccination. Direct injection of allergen extracts into the inguinal lymph nodes and targeting the MHC class-II antigen-presentation pathway by recombinant modular antigen-translocating vaccines have the potential to cure allergic diseases in a very short time.

SUMMARY

The mechanisms of allergic inflammation can be divided into four distinct stages: T cell activation, organ-selective homing, survival/reactivation and effector functions. On the basis of this new knowledge several novel concepts aimed at treating allergic diseases have been developed. The area of allergen-SIT is experiencing exciting developments. Reciprocal regulation of effector and regulatory T cell subsets is being more and more used to develop novel strategies for immunomodulation.

A review of immunomodulators with reference to Canova

Immunomodulators are substances which modify the immunity of an individual to favour a particular immunological response. The immune response and the function of the immune response regulation process are described, with special reference to cancer and autoimmune disease. Homeopathy and its role in immune regulation are discussed with special reference to Canova. Canova is a homeopathic product produced, according to the Hahnemannian homeopathic method, in Brazil. Its role in cancer, bone marrow and haematopoiesis as well as macrophage and monocyte activation is reviewed. Canova seems to stabilize platelet morphology in human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). The data suggest that the future of immunomodulators and homeopathic products which appear to have an effect on the immune response requires a better understanding of the relative need for immune activation versus immune modulation. Homeopathic products specifically need more attention.

Metastatic-promoting effects of LPS: sexual dimorphism and mediation by catecholamines and prostaglandins

Inflammation is implicated in several medical conditions that are sexually dimorphic, including depression, cardiovascular diseases, autoimmunity, and presumably cancer progression. Here we studied the effects of the proinflammatory agent, LPS, on MADB106 lung tumor retention (LTR), and sought to elucidate underlying mechanisms and sexual dimorphism. F344 male and female rats were administered with LPS (0.001-1mg/kg i.v.) simultaneously with tumor cell inoculation, and treated with a beta-blocker (nadolol, 0.2-0.3mg/kg s.c.), a COX inhibitor (indomethacin, 4mg/kg s.c.) or both drugs. To study the role of NK cells, numbers and cytotoxicity of marginating-pulmonary NK cells were studied, and selective in vivo NK-depletion was employed. Serum levels of corticosterone, IL-6, and TNF-alpha were also assessed. The findings indicated that LPS increased LTR in both sexes, but 10-fold higher doses were needed in females to reach the increase evident in males. Additionally, nadolol and indomethacin reduced the effects of LPS, more so in males. In vivo NK-depletion and ex vivo NK activity studies suggested that LPS affected LTR through both NK-independent and NK-dependent mechanisms, the latter mediated through prostaglandin release in males. Corticosterone, IL-6, and TNF-alpha responses to LPS were sexually dimorphic, but were not associated with LPS or drugs' impacts on LTR. Overall, our findings demonstrate sexual dimorphism in LPS-induced elevated susceptibility to MADB106 experimental metastasis, and in potential humoral underlying mechanisms. Further studies are needed to elucidate additional immunological and non-immunological mediators of these dimorphisms, as well as to assess their involvement in other sexually dimorphic pathologies that are associated with inflammation.

Allergen dose dependency of the early- and late-phase cutaneous response in the cynomolgus monkey

BACKGROUND

Cutaneous administration of allergen provides a means to confirm an allergic status, investigate the pathogenesis of allergic diseases, and/or provide a mechanism to evaluate the benefit of new potential therapeutics.

OBJECTIVE

Studies were performed to characterize the allergen-induced cutaneous early- and late-phase response (EPR and LPR) in the cynomolgus monkey.

METHODS

Following intradermal injections of Ascaris suum allergen, the cutaneous weal and flare EPR was measured 15 min post-injection, and skin biopsies were collected at 8-24 h to determine the optimal time of LPR occurrence. Biopsies were analysed for epidermal and dermal inflammatory changes.

RESULTS

The EPR was dose related with a reproducible, measurable response at 1 : 10 000 and maximal at a 1 : 100 allergen dilution. In contrast, the threshold dose required for a reproducible LPR was much greater requiring a dilution of 6 : 100, suggesting independent mechanisms for the EPR and LPR. The LPR 20 h post-allergen injection induced an inflammatory response in the upper and deep dermis. The response was characterized by a moderate perivascular to diffuse inflammation consisting of mononuclear cells, neutrophils and eosinophils. Dexamethasone, while having no effect on the EPR, reduced dermal inflammation (upper dermis, P=0.004; deep dermis, P=0.03). Similarly, dermal eosinophilia was also reduced (upper dermis, P<0.001; deep dermis, P=0.02).

CONCLUSION

Collectively, the results indicate the dose dependency of the EPR and LPR. Furthermore, our observations indicate the value of the LPR response in the cynomolgus monkey to evaluate new therapeutics for the treatment of allergic diseases such as atopic dermatitis.

Pollen generates nitric oxide and nitrite: a possible link to pollen-induced allergic responses

Reactive nitrogen species (RNS), such as nitric oxide (NO), are ubiquitous and diverse signalling molecules involved in a wide range of physiological and pathophysiological processes in both animals and plants. Nitrite, a metabolite of NO turnover, has also been recently characterised as an important mediator of fundamental physiological mechanisms in mammalian cells, and is a substrate for NO production in several plant cell signalling processes. A previous study demonstrated that during plant reproductive processes, intracellular NO is produced by pollen, and that such NO could be important in signalling interactions between pollen and stigma. The aim of this study was to establish whether pollen releases NO and nitrite, using a wide range of plant species. Using a fluorimetric assay in conjunction with electron paramagnetic resonance (EPR) spectroscopy, the present study demonstrated that all hydrating pollen examined released NO, although some appeared to have more activity than others. Additionally, gas phase ozone-based chemiluminescence data showed that nitrite is also released from hydrating pollen. Given that pollen has interactions with other cells, for example in allergenic rhinitis (hay fever) in humans, it suggests that NO might be involved in mediating the responses of both plant and animal cells to pollen. These findings may have important implications for future allergy research, as it is possible that pollen-derived NO and nitrite may impact on mammalian cells during pollen-induced allergic responses.