146 research outputs found
Interleukin 7 from Maternal Milk Crosses the Intestinal Barrier and Modulates T- Cell Development in Offspring
Background
Breastfeeding protects against illnesses and death in hazardous environments, an
effect partly mediated by improved immune function. One hypothesis suggests that
factors within milk supplement the inadequate immune response of the offspring,
but this has not been able to account for a series of observations showing that
factors within maternally derived milk may supplement the development of the
immune system through a direct effect on the primary lymphoid organs. In a
previous human study we reported evidence suggesting a link between IL-7 in
breast milk and the thymic output of infants. Here we report evidence in mice of
direct action of maternally-derived IL-7 on T cell development in the offspring.
Methods and Findings
We have used recombinant IL-7 labelled with a fluorescent dye to trace the
movement in live mice of IL-7 from the stomach across the gut and into the
lymphoid tissues. To validate the functional ability of maternally derived IL-
7 we cross fostered IL-7 knock-out mice onto normal wild type mothers. Subsets
of thymocytes and populations of peripheral T cells were significantly higher
than those found in knock-out mice receiving milk from IL-7 knock-out mothers.
Conclusions/Significance Our study provides direct evidence that interleukin 7,
a factor which is critical in the development of T lymphocytes, when maternally
derived can transfer across the intestine of the offspring, increase T cell
production in the thymus and support the survival of T cells in the peripheral
secondary lymphoid tissue
The Environment of the Malnourished Child
capítulo de libro -- Universidad de Costa Rica, 1976The study of the relation of man to his environment in developing countries
emphasizes the inevitable need for societies to recognize the true causes of
infection, malnutrition, and poverty. The need is for improvement in the quality
of human life in less developed nations, a recommendation easy to prescribe but
difficult to accomplish. Although our pool of knowledge is incomplete, it is
adequate to suggest ways to diminish infection, increase food production, utilize
food more efficiently, improve education, and provide systems of justice to
protect the classes most in need.
The physical environment in tropical and subtropical regions, and the
socioeconomic characteristics of the population inhabiting such regions, favor
maintenance and transmission of a variety of viruses, bacteria, and parasites that
make agricultural progress and social development difficult, and that contribute
to poor fetal growth, nutrient wastage, and deficient postnatal physical growth.
accounting for most of the childhood morbidity and mortality. In this regard.
infections contribute indirectly to the overall food problem in a similar fashion
as pests do in terms of food losses and spoilage. The overall effect could be
comparable or greater than that resulting from an inadequate capacity to
produce or to purchase the food needed.
Thus, my objective has been to stress, within the whole environment, the
importance of infection and the need to diminish it. Waysto control and prevent
infection are readily known. They have to do with education of the population to improve personal and environmental hygiene. Economic investment is necessary
to improve housing and water supply sYstems, waste disposal, and such
preventive measures as immunization programs. Although such measures may
appear expensive when first implemented, they have long-lasting effects and
many require minimal expenditure once they are established. Large segments of
the population stand to benefit, and other development interventions can then
be introduced. However, these measures should not be implemented singly. They
should be accompanied by community development, family planning, social
legislation-in other words, the holistic approach to health and welfare. To do
otherwise may aggravate the problem by stimulating demographic growth, perpetuating
malnutrition and infection, and maintaining underdevelopmentUniversidad de Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA
Mechanistic Insights into a Novel Exporter-Importer System of Mycobacterium tuberculosis Unravel Its Role in Trafficking of Iron
Elucidation of the basic mechanistic and biochemical principles underlying siderophore mediated iron uptake in mycobacteria is crucial for targeting this principal survival strategy vis-à-vis virulence determinants of the pathogen. Although, an understanding of siderophore biosynthesis is known, the mechanism of their secretion and uptake still remains elusive.Here, we demonstrate an interplay among three iron regulated Mycobacterium tuberculosis (M.tb) proteins, namely, Rv1348 (IrtA), Rv1349 (IrtB) and Rv2895c in export and import of M.tb siderophores across the membrane and the consequent iron uptake. IrtA, interestingly, has a fused N-terminal substrate binding domain (SBD), representing an atypical subset of ABC transporters, unlike IrtB that harbors only the permease and ATPase domain. SBD selectively binds to non-ferrated siderophores whereas Rv2895c exhibits relatively higher affinity towards ferrated siderophores. An interaction between the permease domain of IrtB and Rv2895c is evident from GST pull-down assay. In vitro liposome reconstitution experiments further demonstrate that IrtA is indeed a siderophore exporter and the two-component IrtB-Rv2895c system is an importer of ferrated siderophores. Knockout of msmeg_6554, the irtA homologue in Mycobacterium smegmatis, resulted in an impaired M.tb siderophore export that is restored upon complementation with M.tb irtA.Our data suggest the interplay of three proteins, namely IrtA, IrtB and Rv2895c in synergizing the balance of siderophores and thus iron inside the mycobacterial cell
The immune system and the impact of zinc during aging
The trace element zinc is essential for the immune system, and zinc deficiency affects multiple aspects of innate and adaptive immunity. There are remarkable parallels in the immunological changes during aging and zinc deficiency, including a reduction in the activity of the thymus and thymic hormones, a shift of the T helper cell balance toward T helper type 2 cells, decreased response to vaccination, and impaired functions of innate immune cells. Many studies confirm a decline of zinc levels with age. Most of these studies do not classify the majority of elderly as zinc deficient, but even marginal zinc deprivation can affect immune function. Consequently, oral zinc supplementation demonstrates the potential to improve immunity and efficiently downregulates chronic inflammatory responses in the elderly. These data indicate that a wide prevalence of marginal zinc deficiency in elderly people may contribute to immunosenescence
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