Bacterial strain-specific induction of Foxp3+ T regulatory cells is protective in murine allergy models.

BACKGROUND: The incidence of atopic disease has increased dramatically during recent decades and the potential immunoregulatory influence of the microbiota in these individuals is under investigation. OBJECTIVE: The aim of our study was to identify a bacterial strain that is protective in murine allergy models and to determine if microbial induction of T regulatory cells was associated with protection from allergic inflammation. METHODS: Three microbes (Bifidobacterium breve AH1205, B. longum AH1206 and Lactobacillus salivarius AH102) of human origin were fed to newborn, adult and germ-free animals. Induction of Foxp3(+) T regulatory cells was assessed by flow cytometry. Gene array analysis was performed on Peyer's patches. Strains were also examined for their protective effects in the ovalbumin (OVA) respiratory allergy model and the OVA-cholera toxin dietary allergy model. RESULTS: Bifidobacterium longum AH1206 consumption resulted in increased numbers of Foxp3(+) T regulatory cells in infant, adult and germ-free animals. B. breve AH1205 induced Foxp3(+) T regulatory cell expansion only in infant mice while L. salivarius AH102 did not alter T regulatory cell numbers in any animal model tested. B. longum AH1206 reduced the Peyer's patch gene expression associated with antigen presentation, TLR signalling and cytokine production while increasing the expression of genes associated with retinoic acid metabolism. B. longum AH1206 protected against airway inflammation in OVA-sensitized animals and B. longum AH1206 blocked the induction of IgE to orally administered OVA. Neither B. breve AH1205 nor L. salivarius AH102 had a protective effect in either model. CONCLUSION: Bacterial strain-specific induction of Foxp3(+) T regulatory cells in vivo is associated with protection from respiratory and oral allergy.

Analysis of the cellular immune response induced by Bacillus thuringiensis Cry1A toxins in mice: effect of the hydrophobic motif from diphtheria toxin.

Insecticidal Cry1A toxins from Bacillus thuringiensis elicit strong humoral immune response in mice. Previously, we showed that an eight hydrophobic motif amino acid substitution in Domain I did not affect the antibody inducing capacity of the Cry1A toxins, on the contrary, it was enhanced after intranasal immunization. In addition, Cry1A mutants (carrying a substitution of a motif from fragment B of diphtheria toxin into the structurally similar hydrophobic alpha-helix 7 motif of Cry1A toxins) were able to modulate the ratio of IgG subclasses, IgG1/IgG2a. However, the capacity of these toxins to induce cellular immune response has not been studied. Thus, in this work, we investigated the cytokine profile induced after in vitro stimulation with the toxins, in spleen cell cultures from unprimed mice, and intranasally primed mice, with either wild-type Cry1Aa or with mutant toxin Cry1Aa8. Spleen cells from unprimed mice stimulated with Cry1Aa produced very low levels of Th1 (IFN-gamma, IL-12p70) and Th2 type cytokines (IL-10, IL-4), whereas immunization with Cry1Aa8 toxin led to higher production of these cytokines. Restimulation of spleen cells from primed mice with the Cry1Aa induced the production of significant levels of IL-12p70 whereas with Cry1Aa8, IFN-gamma production was stimulated. Interestingly, we found that the capacity of Cry1A toxins to induce cytokine production by lymphocytes was inhibited by N-acetylgalactosamine. Altogether these data demonstrate the immunogenic properties of Cry1A toxins and show that amino acid substitution in Domain I principally affects its ability to induce Th1 cytokines in lymphocytes.

The watershed empires.

Watershed empires, founded by states in the highlands on the upper reaches of river systems, conquered the flood plains and other regions around them. Three of these, Ch'in in ancient China, Assyria in the middle east, and the Inca of Peru, are described, with emphasis on the horrific socio-political systems which they developed. All, however, were eventually overthrown by a combination of internal revolt and external pressures.

William Penn and the peace of Europe.

The Quaker William Penn proposed a European Union to ensure peace in the continent in 1693. Penn was unusual among Quakers in being of the landed upper classes. When converted, he became a leader of the Quakers and other Dissenters. He had the two related ideals of peace and religious toleration, and dreamed of realizing both ideals in the New World. A practical idealist, he took advantage of four factors: friends at Court made through his social position; King Charles II's gratitude for services rendered by his father, Admiral Sir William Penn; the King's desire to conciliate the City merchants, who were ready to invest in Penn's scheme; and above all the King's concern to get North America settled by British colonists. Penn received a charter to found Pennsylvania in 1681. In England he worked hard, especially in collaboration with James II, for toleration for the cruelly persecuted Quakers and other Dissenters. In Pennsylvania he was able to establish complete toleration and his fair and friendly treatment gave the colony 70 years of peaceful co-existence with the Indians. In his essay on the peace of Europe, he virtually invented collective security and with amazing foresight planned in detail something very like the present European Union.

Three wars that never happened.

This article discusses three serious wars that were averted and the three men who averted them. In 1478-79, Pope Sixtus IV's hatred of the Medici culminated in aggressive war against Florence, supported by his powerful ally King Ferrante of Naples. The initial stags of this war were indecisive, but it was about to become much more serious, probably involving all the Italian states and possibly meaning the total destruction of Florence. Lorenzo il Magnifico sailed to Naples, convinced Ferrante this more serious war was against his interests and obtained a generous peace. In 1861, the British Government responded to the boarding of a British ship by a vessel of the American North with a peremptory letter. Albert, Prince Consort, though dying of typhoid fever amended the letter to save Lincoln's face and thus averted war with the North. From 1871 to 1890, Otto von Bismarck worked for a stable peace between the European powers to be attained by arranging meetings of most or all of them to accustom them to solving disputes by negotiation. Two such meetings in Berlin secured 36 years of peace between the powers, despite many disputes, and in particular averted war for possessions in Africa, which could have involved them all.

Efficient system for directed integration into the Lactobacillus acidophilus and Lactobacillus gasseri chromosomes via homologous recombination.

An efficient method is described for the generation of site-specific chromosomal integrations in Lactobacillus acidophilus and Lactobacillus gasseri. The strategy is an adaptation of the lactococcal pORI system (K. Leenhouts, G. Venema, and J. Kok, Methods Cell Sci. 20:35-50, 1998) and relies on the simultaneous use of two plasmids. The functionality of the integration strategy was demonstated by the insertional inactivation of the Lactobacillus acidophilus NCFM lacL gene encoding beta-galactosidase and of the Lactobacillus gasseri ADH gusA gene encoding beta-glucuronidase.

Identification and cloning of gusA, encoding a new beta-glucuronidase from Lactobacillus gasseri ADH.

The gusA gene, encoding a new beta-glucuronidase enzyme, has been cloned from Lactobacillus gasseri ADH. This is the first report of a beta-glucuronidase gene cloned from a bacterial source other than Escherichia coli. A plasmid library of L. gasseri chromosomal DNA was screened for complementation of an E. coli gus mutant. Two overlapping clones that restored beta-glucuronidase activity in the mutant strain were sequenced and revealed three complete and two partial open reading frames. The largest open reading frame, spanning 1,797 bp, encodes a 597-amino-acid protein that shows 39% identity to beta-glucuronidase (GusA) of E. coli K-12 (EC 3.2.1.31). The other two complete open reading frames, which are arranged to be separately transcribed, encode a putative bile salt hydrolase and a putative protein of unknown function with similarities to MerR-type regulatory proteins. Overexpression of GusA was achieved in a beta-glucuronidase-negative L. gasseri strain by expressing the gusA gene, subcloned onto a low-copy-number shuttle vector, from the strong Lactobacillus P6 promoter. GusA was also expressed in E. coli from a pET expression system. Preliminary characterization of the GusA protein from crude cell extracts revealed that the enzyme was active across an acidic pH range and a broad temperature range. An analysis of other lactobacilli identified beta-glucuronidase activity and gusA homologs in other L. gasseri isolates but not in other Lactobacillus species tested.

Population crises and population cycles.

To prevent a population irretrievably depleting its resources, mammals have evolved a behavioural and physiological response to population crisis. When a mammalian population becomes dangerously dense, there is a reversal of behaviour. Co-operation and parental behaviour are replaced by competition, dominance and aggressive violence, leading to high mortality, especially of females and young, and a reduced population. The stress of overpopulation and the resulting violence impairs both the immune and the reproductive systems. Hence epidemics complete the crash of the population, and reproduction is slowed for three or four generations, giving the resources ample time to recover. In some mammal species, crisis and crisis response recur regularly, leading to cycles of population growth and relapse, oscillating about a fixed mean. Population crisis response and population cycles have been equally prominent in the history of human societies. But in man successive advances in food production have made possible growing populations, though with every such advance population soon outgrew resources again. Hence human cycles have been superimposed on a rising curve, producing a saw-tooth graph. Because advances in food production amounted to sudden disturbances in the relations between human populations and their environments, the crisis response in man has failed to avert famine and resource damage. In the large human societies evolved since the coming of settled agriculture and cities, the basic effects of violence, epidemics, famine and resource damage have been mediated by such specifically human disasters as inflation, unemployment, and political tyranny. An account of past crises, periods of relative relief from population pressure, and resulting cycles, is given for a number of regions: China, North Africa and Western Asia, the northern Mediterranean, and north-western Europe. The paper ends with an account of the present world-wide population crisis, and the solution made possible by Malthus's discovery that, unlike animals, we can choose to check population growth by reducing the birth-rate, instead of raising the death-rate, as in other mammals, by the population crisis response.