Tonsil-derived mesenchymal progenitor cells acquire a follicular dendritic cell phenotype under cytokine stimulation

Tonsils comprise part of the mucosal immune system and contain lymphocytes, macrophages, and follicular dendritic cells (FDCs). FDCs are located in the B cell area of the follicles of secondary lymphoid organs, such as the spleen, tonsils, or lymph nodes, and they trap and retain immune complexes on their surfaces to regulate B cell activation and maturation. Stromal cells from the palatine tonsils are often used for FDC in vitro studies, and it has been reported that human palatine tonsils may be a good source of multipotent mesenchymal cells. Therefore, we assessed whether tonsil-derived mesenchymal stromal cells could differentiate into a FDC-like phenotype. We discovered that stromal cells isolated from human tonsils not only had the potential to differentiate into various cell types of mesenchymal origin, but they also could differentiate into FDC-like cells under cytokine stimulation in vitro.     

Growth of ammonia-oxidizing archaea and bacteria in cattle manure compost under various temperatures and ammonia concentrations

A recent study showed that ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) coexist in the process of cattle manure composting. To investigate their physiological characteristics, liquid cultures seeded with fermenting cattle manure compost were incubated at various temperatures (37°C, 46°C, or 60°C) and ammonium concentrations (0.5, 1, 4, or 10?mM NH (4) (+) -N). The growth rates of the AOB and AOA were monitored using real-time polymerase chain reaction analysis targeting the bacterial and archaeal ammonia monooxygenase subunit A genes. AOB grew at 37°C and 4 or 10?mM NH (4) (+) -N, whereas AOA grew at 46°C and 10?mM NH (4) (+) -N. Incubation with allylthiourea indicated that the AOB and AOA grew by oxidizing ammonia. Denaturing gradient gel electrophoresis and subsequent sequencing analyses revealed that a bacterium related to Nitrosomonas halophila and an archaeon related to Candidatus Nitrososphaera gargensis were the predominant AOB and AOA, respectively, in the seed compost and in cultures after incubation. This is the first report to demonstrate that the predominant AOA in cattle manure compost can grow and can probably oxidize ammonia under moderately thermophilic conditions.     

RG-II from Panax ginseng C.A. Meyer suppresses asthmatic reaction

In asthma, T helper 2 (T(H)2)-type cytokines such as interleukin (IL)-4, IL-5, and IL-13 are produced by activated CD4(+) T cells. Dendritic cells played an important role in determining the fate of naive T cells into either T(H)1 or T(H)2 cells. We determined whether RG-II regulates the T(H)1/T(H)2 immune response by using an ovalbumin-induced murine model of asthma. RG-II reduced IL-4 production but increased interferon- gamma production, and inhibited GATA-3 gene expression. RG-II also inhibited asthmatic reactions including an increase in the number of eosinophils in bronchoalveolar lavage fluid, an increase in inflammatory cell infiltration in lung tissues, airway luminal narrowing, and airway hyperresponsiveness. This study provides evidence that RG-II plays a critical role in ameliorating the pathogenic process of asthmatic inflammation in mice. These findings provide new insights into the immunotherapeutic role of RG-II in terms of its effects in a murine model of asthma.     

A cry for help from leaf to root: Aboveground insect feeding leads to the recruitment of rhizosphere microbes for plant self-protection against subsequent diverse attacks

Plants have evolved general and specific defense mechanisms to protect themselves from diverse enemies, including herbivores and pathogens. To maintain fitness in the presence of enemies, plant defense mechanisms are aimed at inducing systemic resistance: in response to the attack of pathogens or herbivores, plants initiate extensive changes in gene expression to activate “systemic acquired resistance” against pathogens and “indirect defense” against herbivores. Recent work revealed that leaf infestation by whiteflies, stimulated systemic defenses against both an airborne pathogen and a soil-borne pathogen, which was confirmed by the detection of the systemic expression of pathogenesis-related genes in response to salicylic acid and jasmonic acid-signaling pathway activation. Further investigation revealed that plants use self protection mechanisms against subsequent herbivore attacks by recruiting beneficial microorganisms called plant growth-promoting rhizobacteria/fungi, which are capable of reducing whitefly populations. Our results provide new evidence that plant-mediated aboveground to belowground communication and vice versa are more common than expected.Key words: aboveground, induced systemic resistance, pepper, plant growth-promoting rhizobacteria, underground, whiteflyAs sessile organisms, plants are unable to actively avoid the attack of predators. To overcome this, plants have evolved a multilayer immune system against herbivores and pathogens.¹ Plants, unlike animals, lack adaptive immunity. Instead, plants are dependent on a heritable, innate immunity based on the recognition by receptors of the presence of microbial triggers (cues) including effector proteins and microbe-associated molecular patterns.¹ The perception of microbial cues leads to the induction of a broad spectrum of plant defenses called systemic acquired resistance (SAR).² Until recently, SAR was thought to be limited to the induction of plant defenses against foliar microbial pathogens. However, recent results suggested that plants can activate signal exchanges between aboveground (AG) and belowground (BG) responses.³ Three phenomena indicate that plants can make use of cues that are systemically indicative of future enemy attack: (1) induced resistance against AG pathogens by BG microbes and vice versa, (2) indirect defenses against AG insects by AG herbivore infestation and (3) BG pathogen infection leading to root exudate-mediated recruitment of BG bacteria. First, many strains of rhizosphere microbes referred to as plant growth-promoting rhizobacteria/fungi (PGPR/PGPF) have beneficial effects by positively affecting plant growth and resistance against foliar plant pathogens—a process known as induced systemic resistance (ISR).⁴ Inducible defense responses triggered by the foliar pathogen Pseudomonas syringae pv. tomato DC3000 included the induction of root secretions such as L-malic acid that effectively recruited a PGPR strain, Bacillus subtilis FB17, in Arabidopsis roots.⁵ Second, herbivore attacks on plants trigger the induction of distinct resistance responses referred to as “indirect defenses.”⁶ In addition to the “direct defense” reaction mediated by the de novo production of toxic secondary compounds against enemies, plants also defend themselves by releasing volatile organic compounds (VOCs) or extrafloral nectar (EFN) to attract natural enemies (carnivores) of the herbivores AG.⁷ Third, as plant root exudates function as BG signaling molecules that affect the composition of rhizosphere microbial populations,⁸ certain rhizobacteria express antifungal-associated genes such as the 2,4-diacetylphloroglucinol biosynthesis gene phlA. The expression of these genes is in turn influenced by root exudates, which are modulated by soilborne fungal infections.⁹In prior studies, only one-way signal transduction was considered, such as AG to BG, AG to AG or BG to BG (Fig. 1).^10–13 The above three examples provide evidence of induced resistance against the same or a similar group of organisms, such as resistance against insects by insects, or against microbes by microbes. However, there are few studies addressing insect-microbe combinations during the elicitation of induced resistance. More specifically, indirect defenses by symbiotic root interactions AG were found, such as the volatile blends released by plants with arbuscular mycorrhizal fungi, which were more attractive to aphid parasitoids than the blends from plants without mycorrhiza.¹⁴ The BG to AG defense responses of plants are not limited to arbuscular mycorrhizal fungi against herbivores. In addition to mycorrhiza-altered insect feeding preferences, a combination of Pseudomonas spp. strains affected the development of leaffolder pest and actively enhanced resistance against leaffolder attack by triggering the synthesis of systemic defense enzymes such as chitinase and proteinase inhibitors in rice plants.¹⁵ Bacillus sp. PGPR strain treatment of tomato triggered ISR to Tomato mottle virus under natural conditions by reducing the population of the silverleaf whitefly vector.¹⁶Open in a separate windowFigure 1Putative model of plant-mediated aboveground to belowground communication and vice versa during the induction of systemic resistance via tritrophic (insect-plant-rhizobacteria) interactions. (A) A plant under normal condition. (B) Whitefly infestation elicits plant systemic defenses against leaf and root pathogens. Chemical cues from root exudates secreted from AG whitefly infestation trigger the recruitment of beneficial microbes including saprophytic fungi, Gram-positive bacteria and actinomycetes. (C) The induction of systemic resistance by colonization by beneficial microbes confers plant self-protection against subsequent herbivore attacks.Recently, we found another type of induced resistance response: bidirectional signal exchanges between AG and BG (Fig. 1).¹⁷ Our study demonstrated that the phloem feeding whiteflies can induce systemic resistance against both a leaf bacterial pathogen and a soil-borne bacterial pathogen. A similar study using the whitefly as an AG feeding insect to test the induction of plant defenses only observed its effects against conspecific insect herbivore competitors AG.¹⁸ However, in our study, foliar attack by the whitefly not only elicited AG resistance against a leaf pathogenic bacterium, Xanthomonas axonopodis pv. vesicatoria, but also enhanced resistance against the soil-borne pathogenic bacterium, Ralstonia solanacearum. The induction of systemic resistance was confirmed by significant upregulation of the SA and JA defense signaling pathway marker genes, Capsicum annuum pathogenesis-related protein (CaPR)1, CaPR4, CaPR10 and Ca protease inhibitor (CaPIN) in both leaves (AG) and roots (BG) after whitefly feeding. Interestingly, AG white-fly feeding significantly increased the population density of beneficial BG microflora including Gram-positive bacteria, actinomycetes and saprophytic fungi that may induce systemic resistance (Fig 1).⁴ Among BG microbial groups, several Grampositive Bacillus sp. strains significantly elicited plant systemic defenses against the whitefly population in the tomato field.¹⁶ Our studies provide a new understanding of tritrophic (insect-plant-PGPR) interactions and their role in the induction of defense mechanisms. In the near future, it will be important to define plant defense signaling molecules from AG to BG and to dissect the signaling transduction pathways using “omics” technology to reveal the mechanisms by which plants protect themselves against enemy attacks.     

Denatured human alpha-defensin attenuates the bactericidal activity and the stability against enzymatic digestion

alpha-Defensin is an antimicrobial peptide which plays an important role in innate immunity. Human defensin (HD)-5 is stored in the Paneth cells of the small intestine as a pro-form and is cleaved by trypsin, which is co-secreted from the Paneth cell granules. The mature HD-5 is protected from further digestion by the proteolysis enzyme. We generated both recombinant HD-5 and proHD-5, and the reduced form of each peptide in order to determine their physiological roles of the disulfide bonds. The reduced proHD-5 attenuated the bactericidal activity and the stability against the trypsin digestion. Human defensin was protected from the enzymatic degradation by disulfide bridges. We further purified the HD-5 with a disulfide variation in the small intestine of Crohn's disease patients. The HD-5 was sensitive to the trypsin treatment. These observations evidently predict that a defensin deficiency may be caused by a disulfide disorder in the disease.     

Characterization of two-substrate fermentation processes for xylitol production using recombinant Saccharomyces cerevisiae containing xylose reductase gene

Fermentation characteristics of recombinant Saccharomyces cerevisiae containing a xylose reductase gene from Pichia stipitis were investigated in an attempt to convert xylose to xylitol, a natural five-carbon sugar alcohol used as a sweetener. Xylitol was produced with a maximum yield of 0.95 g g⁻¹ xylitol xylose consumed in the presence of glucose used as a co-substrate for co-factor regeneration. Addition of glucose caused inhibition of xylose transport and accumulation of ethanol. Such problems were solved by adopting glucose-limited fed-batch fermentations where a high ratio of xylose to glucose was maintained during the bioconversion phase. The optimized two-substrate fed-batch fermentation carried out with S. cerevisiae EH13.15:pY2XR at 30°C resulted in 105.2 g l⁻¹ xylitol concentration with 1.69 g l⁻¹ h⁻¹ productivity.     

Development of an optimal medium for continuous ferrous iron oxidation by immobilized Acidothiobacillus ferrooxidans cells

This study was aimed at developing an immobilized bioreactor system in which long-term continuous ferrous iron oxidation can be realized with no formation of jarosite, which causes clogging of support pores and reactor lines. For this purpose, a medium with no jarosite formation was developed first by selecting optimal nitrogen and phosphate sources and their concentrations. Then with the developed medium containing ammonium phosphate instead of ammonium sulfate and potassium phosphate, repeated batch and continuous operations of ferrous iron oxidation by Acidothiobacillus ferrooxidans cells immobilized in a depth filter were successfully performed for an extended period of time. For about 510 h of operation including 450 h of continuous operation at dilution rates of 0.1, 0.2, and 0.3 h(-)(1), no formation of jarosite and thus no clogging of the reactor system were observed. The maximum ferrous iron oxidation rate was as high as 2.6 g/(L.h) at a dilution rate of 0.3 h(-)(1).     

Calcium Binding Proteins Immunoreactivity in the Rat Basolateral Amygdala Following Myocardial Infarction

In this study, we examined changes in immunoreactivities of calcium binding proteins, such as parvalbumin (PV), calbindin (CB), and calretinin (CR), in the rat basolateral amygdala (BLA) 14 days after myocardial infarction (MI). In the MI-operated group, numbers of PV and CB immunoreactive (⁺) neurons in the BLA were significantly reduced compared to those in the sham-operated group. However, numbers of CR⁺ neurons were slightly, not significantly, reduced in the MI-operated group. These results indicate that MI may decrease the immunoreactivities of PV and CB, not CR, in the rat BLA.