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At least 91 records · Page 5Linked to original sources
PubMed2003

Epicutaneous natural rubber latex sensitization induces T helper 2-type dermatitis and strong prohevein-specific IgE response.

In addition to immediate type I allergy symptoms, natural rubber latex allergy may manifest as protein contact dermatitis on the hands of health-care workers and other natural rubber latex glove users. We examined whether repeated application of natural rubber latex on mouse skin causes sensitization to natural rubber latex and dermatitis. Epicutaneous sensitization with natural rubber latex produced a significant influx of mononuclear cells, CD4+ CD3+ cells, and eosinophils to the sensitized skin sites. The number of degranulated mast cells in natural rubber latex-sensitized skin sites was significantly higher compared with control sites treated with phosphate-buffered saline. The expression of interleukin-1beta and interleukin-4 mRNA was markedly increased in natural rubber latex-sensitized skin sites. Moreover, significant increases in the mRNA expression of chemokines CCL2 (monocyte chemoattractant protein-1), CCL11 (eotaxin-1), CCL3 (macrophage inflammatory protein-1alpha), and CCL4 (macrophage inflammatory protein-1beta) were found. In addition to the cutaneous inflammatory response, epicutaneous sensitization with natural rubber latex induced a striking increase in the total and specific immunoglobulin E levels but not in the immunoglobulin G2a levels. Intraperitoneal immunization with natural rubber latex induced a strong natural rubber latex-specific immunoglobulin G2a response, but only a weak immunoglobulin E response. We also studied the role of two major natural rubber latex allergens, the highly hydrophilic prohevein and the hydrophobic rubber elongation factor. Cutaneous application of natural rubber latex elicited a strong immunoglobulin E response against prohevein, but not against rubber elongation factor. On the contrary, intraperitoneal immunization with natural rubber latex elicited strong immunoglobulin G2a production to rubber elongation factor but not to prohevein. These results demonstrate that epicutaneous sensitization with natural rubber latex induces T helper 2-dominated dermal inflammation and strong immunoglobulin E response in this murine model of natural rubber latex induced protein contact dermatitis. Epicutaneous sensitization to natural rubber latex proteins eluting from latex gloves may therefore contribute to the development of hand dermatitis and also natural rubber latex-specific immunoglobulin E antibodies.

Allergens↗
PubMed2003

The micromorphology and protein characterization of rubber particles in Ficus carica, Ficus benghalensis and Hevea brasiliensis.

Rubber biosynthesis takes place on the surface of rubber particles. These particles are surrounded by a monolayer membrane in which the rubber transferase is anchored. In order to gain better insight into whether rubber particles from different plant species share common structural characteristics, the micromorphology of rubber particles from Ficus carica, Ficus benghalensis, and Hevea brasiliensis was examined by electron microscopy. Rubber particles of all three species were spherical in shape, and the size of rubber particles of H. brasiliensis was much smaller than those of F. carica and F. benghalensis. In addition, investigations were undertaken to compare the cross-reactivity of the antibody raised against either the H. brasiliensis small rubber particle protein (SRPP) which is suggested to be involved in rubber biosynthesis, or the cis-prenyltransferase (CPT) which has an activity similar to rubber transferase. Both western analysis and TEM-immunogold labelling studies showed that rubber particles of F. carica and F. benghalensis do not contain the SRPP. None of the rubber particles in F. carica, F. benghalensis and H. brasiliensis contained the CPT, suggesting that the CPT itself could not catalyse the formation of high molecular weight rubber. These results indicate that rubber particles in the three different plant species investigated share some degree of similarity in architecture, and that the SRPP and CPT themselves are not the core proteins necessary for rubber biosynthesis.

Blotting, Western↗
PubMed1989

Rubber elongation by farnesyl pyrophosphate synthases involves a novel switch in enzyme stereospecificity.

A prenyltransferase purified from the commercial rubber tree, Hevea brasiliensis, that elongates existing cis-polyisoprene rubber molecules also catalyzes the formation of all trans-farnesyl pyrophosphate (t,t-FPP) from dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP). In assays of the latter activity trans-geranyl pyrophosphate is the only other product identified. In contrast to this limited addition of IPP to DMAPP, we measured 7000 additions of isoprene per rubber molecule in a previous titration of active allylic ends of rubber molecules by purified prenyltransferase (Light, D. R., and Dennis, M. S. (1989) J. Biol. Chem. 264, 18589-18597). In order to confirm that purified prenyltransferase extensively elongates rubber molecules, doubly labeled [1-14C]isopentenyl [U-32P]pyrophosphate ([14C,32P]IPP) was synthesized. Using this reagent we show that both prenyltransferase purified from H. brasiliensis and prenyltransferase purified from avian liver (FPP synthase) add greater than 15 isoprene units to existing rubber molecules, consistent with the previous titration data. For confirmation that the prenyltransferase purified from H. brasiliensis adds isoprene units to rubber to make cis-polyisoprene, chirally tritiated [14C]IPP ([14C,2S-3H]IPP) was synthesized. Retention of the tritium label in FPP synthesized from [14C,2S-3H]IPP and DMAPP, geranyl pyrophosphate, or neryl pyrophosphate by prenyltransferase from H. brasiliensis or avian liver confirms trans addition to these substrates. In contrast, when [14C,2S-3H]IPP is incubated with serum-free rubber particles and prenyltransferase purified from H. brasiliensis, avian liver, or yeast, no tritium is incorporated into the rubber particles indicating cis addition. Thus, rubber particles have the ability to alter the stereoselective removal of the 2R-prochiral proton in favor of the removal of the 2S-prochiral proton. This apparent inversion of carbon 2 of IPP during the proton abstraction step by rubber particles represents a novel example of a switch in enzyme stereospecificity. In addition to being enzymatically similar to other prenyltransferases, rubber transferase also appears to be related immunologically to FPP synthases, since polyclonal antibodies to the H. brasiliensis prenyltransferase cross-react with the purified yeast prenyltransferase. In order to investigate potential primers of greater molecular weight than that of FPP, cis-undecaprenyl pyrophosphate (C55PP) was synthesized. C55PP stimulates the incorporation of [14C]IPP into rubber particles suggesting that it may prime new rubber molecules. However, in contrast to DMAPP, C55PP is not incorporated into any detectable products when incubated with prenyltransferase and [14C]IPP in the absence of rubber particles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2001

Similarities and differences in rubber biochemistry among plant species.

This report reviews aspects of the biochemical regulation of rubber yield and rubber quality in three contrasting rubber-producing species, Hevea brasiliensis, Parthenium argentatum and Ficus elastica. Although many similarities are revealed, considerable differences also exist in enzymatic mechanisms regulating biosynthetic rate and the molecular weight of the rubber biopolymers produced. In all three species, rubber molecule initiation, biosynthetic rate and molecular weight, in vitro, are dependent upon substrate concentration and the ratio of isopentenyl pyrophosphate (IPP, the elongation substrate, or monomer) and farnesyl pyrophosphate (FPP, an initiator), but these parameters are affected by intrinsic properties of the rubber transferases as well. All three rubber transferases are capable of producing a wide range of rubber molecular weight, depending upon substrate concentration, clearly demonstrating that the transferases are not the prime determinants of product size in vivo. However, despite these commonalities, considerable differences exist between the species with respect to cosubstrate effects, binding constants, effective concentration ranges, and the role of negative cooperativity in vitro. The P. argentatum rubber transferase appears to exert more control over the molecular weight it produces than the other two species and may, therefore, provide the best prospect for the source of genes for transformation of annual crop species. The kinetic data, from the three contrasting rubber-producing species, also were used to develop a model of the rubber transferase active site in which, in addition to separate IPP and allylic-PP binding sites, there exists a hydrophobic region that interacts with the linear portion of allylic-PP initiator proximal to the pyrophosphate. Substrate affinity increases until the active site is traversed and the rubber interior of the rubber particle is reached. The kinetic data suggest that the hydrophobic region in H. brasiliensis and F. elastica is about 1.8 nm long but only 1.3 nm in P. argentatum. The estimates are supported by measurements of the rubber particle monolayer membrane using electron paramagnetic resonance spectroscopy.

Plants↗