Sequence of the proteinase-inhibitor cystatin homologue from the pollen of Ambrosia artemisiifolia (short ragweed)

Ragweed Pollen Allergy: Burden, Characteristics, and Management of an Imported Allergen Source in Europe

Ambrosia artemisiifolia, also known as common or short ragweed, is an invasive annual flowering herbaceous plant that has its origin in North America. Nowadays, ragweed can be found in many areas worldwide. Ragweed pollen is known for its high potential to cause type I allergic reactions in late summer and autumn and represents a major health problem in America and several countries in Europe. Climate change and urbanization, as well as long distance transport capacity, enhance the spread of ragweed pollen. Therefore ragweed is becoming domestic in non-invaded areas which in turn will increase the sensitization rate. So far 11 ragweed allergens have been described and, according to IgE reactivity, Amb a 1 and Amb a 11 seem to be major allergens. Sensitization rates of the other allergens vary between 10 and 50%. Most of the allergens have already been recombinantly produced, but most of them have not been characterized regarding their allergenic activity, therefore no conclusion on the clinical relevance of all the allergens can be made, which is important and necessary for an accurate diagnosis. Pharmacotherapy is the most common treatment for ragweed pollen allergy but fails to impact on the course of allergy. Allergen-specific immunotherapy (AIT) is the only causative and disease-modifying treatment of allergy with long-lasting effects, but currently it is based on the administration of ragweed pollen extract or Amb a 1 only. In order to improve ragweed pollen AIT, new strategies are required with higher efficacy and safety.

Ragweed-induced allergic rhinoconjunctivitis: current and emerging treatment options

Ragweed (Ambrosia spp.) is an annually flowering plant whose pollen bears high allergenic potential. Ragweed-induced allergic rhinoconjunctivitis has long been seen as a major immunologic condition in Northern America with high exposure and sensitization rates in the general population. The invasive occurrence of ragweed (A. artemisiifolia) poses an increasing challenge to public health in Europe and Asia as well. Possible explanations for its worldwide spread are climate change and urbanization, as well as pollen transport over long distances by globalized traffic and winds. Due to the increasing disease burden worldwide, and to the lack of a current and comprehensive overview, this study aims to review the current and emerging treatment options for ragweed-induced rhinoconjunctivitis. Sound clinical evidence is present for the symptomatic treatment of ragweed-induced allergic rhinoconjunctivitis with oral third-generation H1-antihistamines and leukotriene antagonists. The topical application of glucocorticoids has also been efficient in randomized controlled clinical trials. Combined approaches employing multiple agents are common. The mainstay of causal treatment to date, especially in Northern America, is subcutaneous immunotherapy with the focus on the major allergen, Amb a 1. Beyond this, growing evidence from several geographical regions documents the benefit of sublingual immunotherapy. Future treatment options promise more specific symptomatic treatment and fewer side effects during causal therapy. Novel antihistamines for symptomatic treatment are aimed at the histamine H3-receptor. New adjuvants with toll-like receptor 4 activity or the application of the monoclonal anti-immunoglobulin E antibody, omalizumab, are supposed to enhance conventional immunotherapy. An approach targeting toll-like receptor 9 by synthetic cytosine phosphate–guanosine oligodeoxynucleotides promises a new treatment paradigm that aims to modulate the immune response, but it has yet to be proven in clinical trials.

Kiwifruit allergies

While kiwifruit has a high nutritive and health value, a small proportion of the world's population appears to be allergic to the fruit. IgE-mediated kiwifruit allergy is often associated with birch and grass pollinosis as well as with latex allergy. Isolated allergy to kiwifruit is also relatively common and often severe. Eleven green kiwifruit (Actinidia deliciosa cv. Hayward) allergens recognized to date are termed as Act d 1 through Act d 11. Bet v 1 homologue (Act d 8) and profilin (Act d 9) are important allergens in polysensitized subjects, whereas actinidin (Act d 1) is important in kiwifruit monosensitized subjects. Differences in allergenicity have been found among kiwifruit cultivars. Allergy sufferers might benefit from the selection and breeding of low-allergenic kiwifruit cultivars.

Immunologic analysis of monoclonal and immunoglobulin E antibody epitopes on natural and recombinant Amb a 1

BACKGROUND

Amb a 1 is the major allergen from ragweed pollen and more than 90% of ragweed-allergic patients react with this protein. Although Amb a 1 was cloned and sequenced in 1991, little is known of the specificity of anti-Amb a 1 antibodies or of the immunologic properties of the recombinant allergen.

OBJECTIVE

To compare binding of monoclonal antibodies (mAb) and IgE antibodies to purified natural Amb a 1 (nAmb a 1) and recombinant Amb a 1 (rAmb a 1).

METHODS

Binding of a panel of anti-Amb a 1 mAb and IgE antibodies to nAmb a 1 or rAmb a 1 was compared by immunoblotting. Chimeric ELISA was used to measure specific IgE to these allergens using 89 ragweed-allergic sera from Austria, Italy, Canada and the United States.

RESULTS

The 8 mAb bound to a 38 kDa Amb a 1 band in ragweed pollen extract and a subset of 5 mAb also bound to the 26 kDa chain of nAmb a 1. A two-site ELISA was developed using a mAb pair, which was approximately 10-fold more sensitive to rAmb a 1. There was a significant correlation between IgE antibody binding to nAmb a 1 and rAmb a 1 (n=89, r=0.79, P<0.001). A subset of approximately 40% of patients showed greater reactivity to nAmb a 1 than to rAmb a 1.

CONCLUSIONS

The data suggest that there is less reactivity of human IgE to rAmb a 1 compared with nAmb a 1. The development of more sensitive, quantitative ELISA for Amb a 1 will require the production of new mAb especially directed against nAmb a 1.

Protein proteinase inhibitor genes in combat against insects, pests, and pathogens: natural and engineered phytoprotection

The continual need to increase food production necessitates the development and application of novel biotechnologies to enable the provision of improved crop varieties in a timely and cost-effective way. A milestone in this field was the introduction of Bacillus thuringiensis (Bt) entomotoxic proteins into plants. Despite the success of this technology, there is need for development of alternative strategies of phytoprotection. Biotechnology offers sustainable solutions to the problem of pests, pathogens, and plant parasitic nematodes in the form of other insecticidal protein genes. A variety of genes, besides (Bt) toxins that are now available for genetic engineering for pest resistance are genes for vegetative insecticidal proteins, proteinase inhibitors, alpha-amylase inhibitors, and plant lectins. This review presents a comprehensive summary of research efforts that focus on the potential use and advantages of using proteinase inhibitor genes to engineer insect- and pest-resistance. Crop protection by means of PI genes is an important component of Integrated Pest Management programmes.

Plant seed cystatins and their target enzymes of endogenous and exogenous origin

Cystatins are protein inhibitors of cysteine proteinases of the papain family, and those of animal origin have long been studied from medical and physiological aspects. In the meantime, oryzacystatin cloned from rice seeds in 1987 was recognized as the first well-defined cystatin of plant origin. Cloning studies followed to disclose various plant cytstatins including those of corn and soybean origin, their similarities to and differences from animal cystatins being analyzed in detail. Plant seed cystatins are now understood as factors controlling germination by inhibition of endogenous cysteine proteinases. They can also recognize insect midgut proteinases as exogenous target enzymes to control. This paper discusses chemical and phytophysiological relationships between cystatins and their targets.

Purification and characterization of a novel endopeptidase in ragweed (Ambrosia artemisiifolia) pollen

Ragweed (Ambrosia artemisiifolia), the major cause of late summer hay fever (allergic rhinitis) in the United States and Canada, is clinically the most important source of the seasonal aeroallergens. A novel endopeptidase was extracted from the pollen of this plant and purified by a series of column chromatographic steps. It has a molecular mass of 82 kDa according to gel filtration and SDS-polyacrylamide gel electrophoresis and a pH optimum near 9.0, and its activity is unaffected by chelating or reducing agents. A 17-amino acid amino-terminal sequence of this protein showed no similarity with any other proteases. The enzyme was inhibited by diisopropyl fluorophosphate, a general serine class inhibitor, and more specifically N-p-tosyl-L-phenylalanine chloromethyl ketone, a chymotrypsin-like proteinase inhibitor. Various synthetic substrates were efficiently cleaved with a strong preference for Phe in the P1 and P3 position and Pro in the P2 position. This specificity was confirmed through inhibition studies with both peptidyl chloromethyl ketone and organophosphate inhibitors. In addition to synthetic substrates, the neuropeptides, vasoactive intestinal peptide and substance P, which are required for normalized lung functions, were also rapidly hydrolyzed. Activity toward protein substrates was not detected with the exception of the inactivation of alpha-1-proteinase inhibitor, which occurred through cleavage within the reactive site loop. These results indicate that the purified enzyme is a novel endopeptidase, which may be involved in both the degradation of neuropeptides and the inactivation of protective proteinase inhibitors during pollen-initiated allergic reactions.

IgE-binding trypsin inhibitors in plant pollen extracts

In an attempt to access the possible role of protease-antiprotease mechanisms of non-immune defence in pollinosis, only low levels of trypsin-, kallikrein- or plasmin-like proteinases could be detected in aqueous pollen extracts. In contrast, several pollen species displayed appreciable trypsin inhibitory activity, e.g. Parietaria, Olea, Ambrosia, Rumex, Chenopodium, Holcus and Poa spp. These proteins of the serpin family of anti-proteinases were found to bind specific IgE-antibodies from the serum of hay fever patients. As examples, the IgE-binding trypsin inhibitors from the pollen of Parietaria judaica and Ambrosia elatior were purified and characterized as acidic proteins with pI 4.2 and a molecular weight of 20-24 kDa.

Inhibition of cysteine proteinases by Carica papaya cystatin produced in Escherichia coli

A papaya cystatin (Cst)-encoding cDNA clone was isolated from a papaya leaf cDNA library and the active protein produced in Escherichia coli. The amino-acid sequence reveals a protein of 11,262 Da with over 40% identity to other published plant Cst. Unique features of the papaya Cst include a single Cys residue, variation in the papain-binding region, and the first reported inhibition of papaya proteinase IV by a Cst.