急求一篇5000个词的英文文献.关于物流食品安全问题的

Novel Foods to Treat Food Allergy and
Gastrointestinal Infection
Hilary A。Perr,MD(棰樼洰銆佷綔鑰?
Address
Evolving Foods and Children鈥檚 Health,Division of Pediatric
Gastroenterology,Hepatology,and Nutrition,California Pacific
Medical Center,Box 7999,San Francisco,CA 94120,USA。
E-mail:hperr@itsa。ucsf。edu
Current Gastroenterology Reports 2004,6:254鈥?60
Current Science Inc。ISSN 1522-8037
Copyright © 2004 by Current Science Inc。
(姝ｆ枃)
The gastrointestinal tract communicates directly with the
external environment。Necessary nutrients must be absorbed
and commensal bacteria tolerated,and foreign proteins,
antigens,and pathogens must be simultaneously excluded or
destroyed。Immaturity or disruption of the mucosal immune
defenses increases vulnerability to food allergy,intolerance,
and infectious disease。Diseases resulting from ingested foreign
proteins and organisms are increasing and cause morbidity and
mortality worldwide。There is no specific treatment for food
allergy other than avoidance。Vaccination for infectious disease
is limited by the cost and logistics of distribution and
administration,particularly in developing countries。Novel
strategies are being explored to modulate the gut mucosal
immune system by altering protein expression in food。Crops
are being developed to remove deleterious allergens to
prevent immunogenic exposure while preserving nutritional
quality。Local food plants that express protein fragments of
pathogens might provide an effective means to stimulate gut
mucosal immunity while increasing vaccine accessibility。
Introduction
Aberrant immune responses to ingested foreign proteins or
pathogens may lead to the expression of allergic,autoimmune,
or infectious disease in the gastrointestinal tract。
Ideally,the mucosal immune response inactivates the foreign
protein without injuring the host。Cellular and noncellular
mechanisms participate [1]。Gastrointestinal proteolytic
enzymes,extremes in pH,and emulsification by bile reduce
antigenic potential。The mucin glycoprotein layer,secretory
immunoglobulin A (sIgA),and epithelial tight junctions
impede attachment and passage of foreign proteins。Junctional
integrity may be compromised during the perinatal
period,inflammation,and food allergy,permitting luminal
antigens and pathogens to gain access to the lamina propria。
Once the epithelial barrier is breeched,allergens may crosslink with IgE,thereby stimulating mast cell degranulation,
epithelial fluid,and electrolyte secretion。
Food allergy arises when an oral allergen provokes an
abnormal immune response。Responses occur by IgE-mediated
or non-IgE cellular mechanisms。IgE causes hives,wheezing,
and hypotension。A mixed pathology can manifest as
gastrointestinal symptoms resulting from eosinophilic
inflammation and increased vascular permeability。Clinical
forms of delayed cell-mediated non-IgE pathology include
celiac disease and protein enteropathy [2]。
Luminal presentation of an antigen,in a food or vaccine,
is an important means of stimulating mucosal immunity
[3,4]。The antigen is taken up by specialized M cells within the
intestinal lining and transferred to macrophages and B cells。
Portions of the antigen displayed on macrophage membranes
stimulate T-helper (Th) cells and activate B cells to produce
neutralizing antibodies。Later ingestion of an intact pathogen
elicits memory Th cells to produce cytotoxic T cells,which
attack infected cells。Memory Th cells also induce a brisk
secretion of antibodies by stimulated B cells。Therefore,oral
vaccines can be a particularly effective first line of defense
against many of the ingested pathogens responsible for
gastrointestinal disease。
New strategies are being explored to modulate the gut
mucosal immune system by altering protein expression in
food plants。Food allergens can be removed from food plants
by mutagenesis,gene silencing,or antisense oligonucleotides。
Conversely,novel proteins can be expressed in plants to create
edible vaccines。Recombinant DNA technology can be used to
transfer genes from other organisms to plants。Similar technology
has already been employed to make human insulin。
One method of gene transfer involves coating microscopic
metal particles with the desired DNA and accelerating the
particles directly into plant cells with a particle gun。Alternatively,
the gene of interest can be inserted into the DNA of a
bacterial or yeast plasmid。Plasmid-bearing bacteria then
transfer recombinant DNA into host plant cells,where the
recombinant DNA incorporates into the plant genome。Transfer
of the recombinant DNA into the plant cell by either
method is followed by plant cell division,eventually yielding
a plant with the transferred trait。