151
|
Abstract
Increasingly, epidemiologic and clinical data support the hypothesis that perturbations in the gastrointestinal (GI) microbiota because of antibiotic use and dietary differences in 'industrialized' countries have disrupted the normal microbiota-mediated mechanisms of immunological tolerance in the mucosa, leading to an increase in the incidence of allergic airway disease. The data supporting this 'microflora hypothesis' includes correlations between allergic airway disease and (1) antibiotic use early in life, (2) altered fecal microbiota and (3) dietary changes over the past two decades. Our laboratory has recently demonstrated that mice can develop allergic airway responses to allergens if their endogenous microbiota is altered at the time of first allergen exposure. These experimental and clinical observations are consistent with other studies demonstrating that the endogenous microbiota plays a significant role in shaping the development of the immune system. Data are beginning to accumulate that a 'balanced' microbiota plays a positive role in maintaining mucosal immunologic tolerance long after post-natal development. Other studies have demonstrated that even small volumes delivered to the nasopharynx largely end up in the GI tract, suggesting that airway tolerance and oral tolerance may operate simultaneously. The mechanism of microbiota modulation of host immunity is not known; however, host and microbial oxylipins are one potential set of immunomodulatory molecules that may control mucosal tolerance. The cumulative data are beginning to support the notion that probiotic and prebiotic strategies be considered for patients coming off of antibiotic therapy.
Collapse
Affiliation(s)
- M C Noverr
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109-0642, USA
| | | |
Collapse
|
152
|
Tsitsigiannis DI, Keller NP. Oxylipins act as determinants of natural product biosynthesis and seed colonization in Aspergillus nidulans. Mol Microbiol 2006; 59:882-92. [PMID: 16420358 DOI: 10.1111/j.1365-2958.2005.05000.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Secreted, hormone-like lipogenic molecules, called oxylipins, mediate the balance of asexual to sexual spore ratio in Aspergillus nidulans. Oxylipin production in this fungus is dependent on developmental regulation of three conserved fatty acid oxygenases, PpoA, PpoB and PpoC. Here, we show that in addition to altering spore ratios, loss of ppo genes affect natural product biosynthesis and seed colonization. DeltappoA;DeltappoC and DeltappoA;DeltappoB;DeltappoC mutants were unable to produce the mycotoxin sterigmatocystin (ST) in vitro or in planta but in contrast overproduced the antibiotic penicillin (PN). These findings were correlated with decreased expression of genes involved in ST biosynthesis and increased expression of a PN biosynthetic gene, thus suggesting that oxylipin species regulate secondary metabolites at the transcriptional level. Additionally, the DeltappoA;DeltappoC and the DeltappoA;DeltappoB;DeltappoC mutants were defective in colonization of peanut seeds as reflected by a decrease in conidiation and production of the seed degradative enzyme lipase. These results indicate that oxylipin production is important for host colonization and mycotoxin production and may provide a promising target for future control strategies.
Collapse
|
153
|
Scupham AJ, Presley LL, Wei B, Bent E, Griffith N, McPherson M, Zhu F, Oluwadara O, Rao N, Braun J, Borneman J. Abundant and diverse fungal microbiota in the murine intestine. Appl Environ Microbiol 2006; 72:793-801. [PMID: 16391120 PMCID: PMC1352209 DOI: 10.1128/aem.72.1.793-801.2006] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Enteric microbiota play a variety of roles in intestinal health and disease. While bacteria in the intestine have been broadly characterized, little is known about the abundance or diversity of enteric fungi. This study utilized a culture-independent method termed oligonucleotide fingerprinting of rRNA genes (OFRG) to describe the compositions of fungal and bacterial rRNA genes from small and large intestines (tissue and luminal contents) of restricted-flora and specific-pathogen-free mice. OFRG analysis identified rRNA genes from all four major fungal phyla: Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota. The largest assemblages of fungal rRNA sequences were related to the genera Acremonium, Monilinia, Fusarium, Cryptococcus/Filobasidium, Scleroderma, Catenomyces, Spizellomyces, Neocallimastix, Powellomyces, Entophlyctis, Mortierella, and Smittium and the order Mucorales. The majority of bacterial rRNA gene clones were affiliated with the taxa Bacteroidetes, Firmicutes, Acinetobacter, and Lactobacillus. Sequence-selective PCR analyses also detected several of these bacterial and fungal rRNA genes in the mouse chow. Fluorescence in situ hybridization analysis with a fungal small-subunit rRNA probe revealed morphologically diverse microorganisms resident in the mucus biofilm adjacent to the cecal and proximal colonic epithelium. Hybridizing organisms comprised about 2% of the DAPI (4',6-diamidino-2-phenylindole, dihydrochloride)-positive organisms in the mucus biofilm, but their abundance in fecal material may be much lower. These data indicate that diverse fungal taxa are present in the intestinal microbial community. Their abundance suggests that they may play significant roles in enteric microbial functions.
Collapse
MESH Headings
- Animals
- Bacteria/classification
- Bacteria/genetics
- Bacteria/isolation & purification
- DNA, Bacterial/analysis
- DNA, Bacterial/isolation & purification
- DNA, Fungal/analysis
- DNA, Fungal/isolation & purification
- Female
- Fungi/classification
- Fungi/genetics
- Fungi/isolation & purification
- Genes, rRNA
- In Situ Hybridization, Fluorescence
- Intestine, Large/microbiology
- Intestine, Small/microbiology
- Male
- Mice
- Mice, Inbred C57BL
- Molecular Sequence Data
- Oligonucleotide Probes
- Polymerase Chain Reaction
- RNA, Ribosomal/genetics
- Sequence Analysis, DNA
- Specific Pathogen-Free Organisms
Collapse
|
154
|
Stanley D. Prostaglandins and other eicosanoids in insects: biological significance. ANNUAL REVIEW OF ENTOMOLOGY 2006; 51:25-44. [PMID: 16332202 DOI: 10.1146/annurev.ento.51.110104.151021] [Citation(s) in RCA: 184] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Prostaglandins and other eicosanoids are oxygenated metabolites of certain polyunsaturated fatty acids. These compounds are well known for their important actions in mammalian physiology and disease. Recent work has revealed the presence and biological actions of eicosanoids in insects and many other invertebrate animals. In insects, eicosanoids mediate cellular immunity to microbial and metazoan challenge. Notably, some infectious organisms secrete factors responsible for impairing host insect immune reactions by inhibiting biosynthesis of eicosanoids. Eicosanoids also act in insect reproductive biology, in ion transport physiology, and in fever response to infection as well as in protein exocytosis in tick salivary glands. Aside from ongoing actions in homeostasis, certain eicosanoid actions occur at crucial points in insect life histories, such as during infectious challenge and important events in reproduction.
Collapse
Affiliation(s)
- David Stanley
- USDA/ARS, Biological Control of Insects Research Laboratory, Columbia, Missouri 65203, USA.
| |
Collapse
|
155
|
Zhu P, Liu X, Labelle EF, Freedman BD. Mechanisms of hypotonicity-induced calcium signaling and integrin activation by arachidonic acid-derived inflammatory mediators in B cells. THE JOURNAL OF IMMUNOLOGY 2005; 175:4981-9. [PMID: 16210600 DOI: 10.4049/jimmunol.175.8.4981] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We previously characterized the initial steps in the activation of novel (calcium-permeant) nonselective cation channels (NSCCs) and calcium release-activated calcium channels in primary murine B lymphocytes. Phospholipase C products, namely diacylglycerol and d-myo-inositol 1,4,5-trisphosphate, were identified as proximal intracellular agonists of these respective channels following mechanical stimulation of B cells. However, neither the distal steps in NSCC activation nor the contribution of these channels to sustained mechanical signaling were defined in these previous studies. In this study, single cell measurements of intracellular Ca(2+) were used to define the mechanisms of NSCC activation and demonstrate a requirement for arachidonic acid liberated from diacylglycerol. Several arachidonic acid-derived derivatives were identified that trigger Ca(2+) entry into B cells, including the lipoxygenase product 5-hydroperoxyeicosatetranenoic acid and the cytochrome P450 hydroxylase product 20-hydroxyeicosatetraenoic; however, the cytochrome P450 epoxygenase product 5,6-epoxyeicosatrienoic acid is primarily responsible for hypotonicity-induced responses. In addition to regulating calcium entry, our data suggest that eicosanoid-activated NSCCs have a separate and direct role in regulating the avidity of integrins on B cells for extracellular matrix proteins, including ICAM-1 and VCAM-1. Thus, in addition to defining a novel osmotically activated signal transduction pathway in B cells, our results have broad implications for understanding how inflammatory mediators dynamically and rapidly regulate B cell adhesion and trafficking.
Collapse
Affiliation(s)
- Peimin Zhu
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
| | | | | | | |
Collapse
|
156
|
Prost I, Dhondt S, Rothe G, Vicente J, Rodriguez MJ, Kift N, Carbonne F, Griffiths G, Esquerré-Tugayé MT, Rosahl S, Castresana C, Hamberg M, Fournier J. Evaluation of the antimicrobial activities of plant oxylipins supports their involvement in defense against pathogens. PLANT PHYSIOLOGY 2005; 139:1902-13. [PMID: 16299186 PMCID: PMC1310568 DOI: 10.1104/pp.105.066274] [Citation(s) in RCA: 286] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Plant oxylipins are a large family of metabolites derived from polyunsaturated fatty acids. The characterization of mutants or transgenic plants affected in the biosynthesis or perception of oxylipins has recently emphasized the role of the so-called oxylipin pathway in plant defense against pests and pathogens. In this context, presumed functions of oxylipins include direct antimicrobial effect, stimulation of plant defense gene expression, and regulation of plant cell death. However, the precise contribution of individual oxylipins to plant defense remains essentially unknown. To get a better insight into the biological activities of oxylipins, in vitro growth inhibition assays were used to investigate the direct antimicrobial activities of 43 natural oxylipins against a set of 13 plant pathogenic microorganisms including bacteria, oomycetes, and fungi. This study showed unequivocally that most oxylipins are able to impair growth of some plant microbial pathogens, with only two out of 43 oxylipins being completely inactive against all the tested organisms, and 26 oxylipins showing inhibitory activity toward at least three different microbes. Six oxylipins strongly inhibited mycelial growth and spore germination of eukaryotic microbes, including compounds that had not previously been ascribed an antimicrobial activity, such as 13-keto-9(Z),11(E),15(Z)-octadecatrienoic acid and 12-oxo-10,15(Z)-phytodienoic acid. Interestingly, this first large-scale comparative assessment of the antimicrobial effects of oxylipins reveals that regulators of plant defense responses are also the most active oxylipins against eukaryotic microorganisms, suggesting that such oxylipins might contribute to plant defense through their effects both on the plant and on pathogens, possibly through related mechanisms.
Collapse
Affiliation(s)
- Isabelle Prost
- Unité Mixte de Recherche 5546 Centre National de la Recherche Scientifique-Université Paul Sabatier, Pôle de Biotechnologie Végétale, 31326 Castanet-Tolosan, France
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
157
|
van Heerden A, Kock JLF, Botes PJ, Pohl CH, Strauss CJ, van Wyk PWJ, Nigam S. Ascospore release from bottle-shaped asci in. FEMS Yeast Res 2005; 5:1185-90. [PMID: 16024297 DOI: 10.1016/j.femsyr.2005.04.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Revised: 04/13/2005] [Accepted: 04/22/2005] [Indexed: 11/19/2022] Open
Abstract
Yeasts utilize different mechanisms to release ascospores of different lengths from bottle-shaped asci. Using electron microscopy, confocal laser scanning microscopy, gas chromatography-mass spectrometry and digital live imaging, the individual release of oval ascospores from tight-fitting narrow bottle-necks, is reported in the yeast Dipodascus albidus. These ascospores are surrounded by compressible, oxylipin-coated sheaths enabling ascospores to slide past each other when forced by turgor pressure and by possible sheath contractions towards the narrowing ascus-neck. In this paper, the release mechanisms of ascospores of various lengths from bottle-shaped asci and produced by different yeasts are compared. We suggest that different release mechanisms, utilizing compressible sheaths or geared-alignment, have possibly evolved to compensate for variation in ascospore length. Alternatively, sheaths and ridges might be two evolutionary solutions to the same biomechanical problem, i.e. to release ascospores irrespective of length from bottle-shaped asci.
Collapse
Affiliation(s)
- Ané van Heerden
- UNESCO-MIRCEN, Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, P.O. Box 339, Bloemfontein 9301, South Africa
| | | | | | | | | | | | | |
Collapse
|
158
|
Alem MA, Douglas LJ. Prostaglandin production during growth of Candida albicans biofilms. J Med Microbiol 2005; 54:1001-1005. [PMID: 16192429 DOI: 10.1099/jmm.0.46172-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Both biofilms and planktonic (suspended) cells of Candida albicans synthesized extracellular prostaglandin(s) during growth at 37 degrees C, but biofilm cells secreted significantly more prostaglandin(s) when production was determined on the basis of cell dry weight. Prostaglandin synthesis by both cell types was sensitive to the cyclooxygenase inhibitors aspirin, diclofenac and etodolac. A morphological mutant blocked in two signalling pathways (cph1/cph1 efg1/efg1) produced prostaglandin levels similar to those of the parent strain, but formed yeast-only biofilms. These results suggest that prostaglandin production could be a significant virulence factor in biofilm-associated infections, although its role in C. albicans morphogenesis remains unclear.
Collapse
Affiliation(s)
- Mohammed As Alem
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - L Julia Douglas
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK
| |
Collapse
|
159
|
Liu X, Zhu P, Freedman BD. Multiple eicosanoid-activated nonselective cation channels regulate B-lymphocyte adhesion to integrin ligands. Am J Physiol Cell Physiol 2005; 290:C873-82. [PMID: 16251477 DOI: 10.1152/ajpcell.00229.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Arachidonic acid (AA) is a substrate for a variety of proinflammatory mediators, which are generated by cyclooxygenases (COXs), lipoxygenases (LOXs), and cytochrome P-450 (CYP450) enzymes. COX (e.g., PGs and prostacyclins) and LOX (e.g., leukotrienes) products have well-established proinflammatory roles; however, little is known about the functions of CYP450 products in leukocytes. We previously found that mechanical strain generated by subjecting lymphocytes to hypotonic challenge triggered AA production and that two CYP450 products of AA, 5,6-epoxyeicosatrienoic acid (5,6-EET) and 20-hydroxyeicosatetraenoic acid (20-HETE), as well as a product of LOX, 5-(S)-hydroperoxyeicosatetrenoic acid (5-HPETE), induced Ca(2+) entry into primary B cells. The main goal of the present studies, therefore, was to define the biophysically properties of eicosanoid-activated channels responsible for Ca(2+) entry and the physiological consequences of activating these channels, including their role in mechanical signaling. We found that 5,6-EET, 20-HETE, and 5-HPETE each activated distinct Ca(2+)-permeant nonselective cation channels (NSCCs) in primary B cells. These NSCCs each regulate plasma membrane potential and B-cell adhesion to integrin ligands ICAM-1 and VCAM-1. Thus our data demonstrate that proinflammatory mediators produced in response to osmotic and/or physical stress play a direct role in regulating the B-cell membrane potential and their adhesion to specific ECM proteins. These results not only have important implications for understanding normal mechanisms of B-cell activation, differentiation, and trafficking but also point to novel targets for modulating the pathogenesis of B-cell-mediated inflammatory diseases.
Collapse
Affiliation(s)
- Xiaohong Liu
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 368E Old Vet Bldg., 3800 Spruce St., Philadelphia, PA 19104, USA
| | | | | |
Collapse
|
160
|
Kandel S, Morant M, Benveniste I, Blée E, Werck-Reichhart D, Pinot F. Cloning, Functional Expression, and Characterization of CYP709C1, the First Sub-terminal Hydroxylase of Long Chain Fatty Acid in Plants. J Biol Chem 2005; 280:35881-9. [PMID: 16120613 DOI: 10.1074/jbc.m500918200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We cloned and characterized CYP709C1, a new plant cytochrome P450 belonging to the P450 family, that so far has no identified function except for clustering with a fatty acid metabolizing clade of P450 enzymes. We showed here that CYP709C1 is capable of hydroxylating fatty acids at the omega-1 and omega-2 positions. This work was performed after recoding and heterologous expression of a full-length cDNA isolated from a wheat cDNA library in an engineered yeast strain. Investigation on substrate specificity indicates that CYP709C1 metabolizes different fatty acids varying in their chain length (C12 to C18) and unsaturation. CYP709C1 is the first identified plant cytochrome P450 that can catalyze sub-terminal hydroxylation of C18 fatty acids. cis-9,10-Epoxystearic acid is metabolized with the highest efficiency, i.e. K((m)(app)) of 8 microM and V(max(app)) of 328 nmol/min/nmol P450. This, together with the fact that wheat possesses a microsomal peroxygenase able to synthesize this compound from oleic acid, strongly suggests that it is a physiological substrate. Hydroxylated fatty acids are implicated in plant defense events. We postulated that CYP709C1 could be involved in plant defense by producing such compounds. This receives support from the observation that (i) sub-terminal hydroxylation of 9,10-epoxystearic acid is induced (15-fold after 3 h) in microsomes of wheat seedlings treated with the stress hormone methyl jasmonate and (ii) CYP709C1 is enhanced at the transcriptional level by this treatment. CYP709C1 transcript also accumulated after treatment with a combination of the safener naphthalic acid anhydride and phenobarbital. This indicates a possible detoxifying function for CYP709C1 that we discussed.
Collapse
Affiliation(s)
- Sylvie Kandel
- Département Réponse Métabolique à l'Environnement Biotique, IBMP-CNRS, UPR 2357, 28 Rue Goethe, F-67083 Strasbourg Cedex, France
| | | | | | | | | | | |
Collapse
|
161
|
Tsitsigiannis DI, Bok JW, Andes D, Nielsen KF, Frisvad JC, Keller NP. Aspergillus cyclooxygenase-like enzymes are associated with prostaglandin production and virulence. Infect Immun 2005; 73:4548-59. [PMID: 16040966 PMCID: PMC1201276 DOI: 10.1128/iai.73.8.4548-4559.2005] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oxylipins comprise a family of oxygenated fatty acid-derived signaling molecules that initiate critical biological activities in animals, plants, and fungi. Mammalian oxylipins, including the prostaglandins (PGs), mediate many immune and inflammation responses in animals. PG production by pathogenic microbes is theorized to play a role in pathogenesis. We have genetically characterized three Aspergillus genes, ppoA, ppoB, and ppoC, encoding fatty acid oxygenases similar in sequence to specific mammalian prostaglandin synthases, the cyclooxygenases. Enzyme-linked immunosorbent assay analysis showed that production of PG species is decreased in both Aspergillus nidulans and A. fumigatus ppo mutants, implicating Ppo activity in generating PGs. The A. fumigatus triple-ppo-silenced mutant was hypervirulent in the invasive pulmonary aspergillosis murine model system and showed increased tolerance to H(2)O(2) stress relative to that of the wild type. We propose that Ppo products, PG, and/or other oxylipins may serve as activators of mammalian immune responses contributing to enhanced resistance to opportunistic fungi and as factors that modulate fungal development contributing to resistance to host defenses.
Collapse
|
162
|
Tsitsigiannis DI, Kowieski TM, Zarnowski R, Keller NP. Endogenous lipogenic regulators of spore balance in Aspergillus nidulans. EUKARYOTIC CELL 2005; 3:1398-411. [PMID: 15590815 PMCID: PMC539017 DOI: 10.1128/ec.3.6.1398-1411.2004] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ability of fungi to produce both meiospores and mitospores has provided adaptive advantages in survival and dispersal of these organisms. Here we provide evidence of an endogenous mechanism that balances meiospore and mitospore production in the model filamentous fungus Aspergillus nidulans. We have discovered a putative dioxygenase, PpoC, that functions in association with a previously characterized dioxygenase, PpoA, to integrate fatty acid derived oxylipin and spore production. In contrast to PpoA, deletion of ppoC significantly increased meiospore production and decreased mitospore development. Examination of the PpoA and PpoC mutants indicate that this ratio control is associated with two apparent feedback loops. The first loop shows ppoC and ppoA expression is dependent upon, and regulates the expression of, nsdD and brlA, genes encoding transcription factors required for meiospore or mitospore production, respectively. The second loop suggests Ppo oxylipin products antagonistically signal the generation of Ppo substrates. These data support a case for a fungal "oxylipin signature-profile" indicative of relative sexual and asexual spore differentiation.
Collapse
|
163
|
Tsitsigiannis DI, Kowieski TM, Zarnowski R, Keller NP. Three putative oxylipin biosynthetic genes integrate sexual and asexual development in Aspergillus nidulans. Microbiology (Reading) 2005; 151:1809-1821. [PMID: 15941990 DOI: 10.1099/mic.0.27880-0] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Oxylipins called psi factors have been shown to alter the ratio of asexual to sexual sporulation in the filamentous fungusAspergillus nidulans. Analysis of theA. nidulansgenome has led to the identification of three fatty acid oxygenases (PpoA, PpoB and PpoC) predicted to produce psi factors. Here, it is reported that deletion ofppoB(ΔppoB) reduced production of the oleic-acid-derived oxylipin psiBβand increased the ratio of asexual to sexual spore development. Generation of the triple mutant ΔppoAΔppoBΔppoCresulted in a strain deficient in producing oleic- and linoleic-acid-derived 8′-hydroxy psi factor and caused increased and mis-scheduled activation of sexual development. Changes in asexual to sexual spore development were positively correlated to alterations in the expression ofbrlAandveA, respectively. PpoB and/or its products antagonistically mediate the expression levels ofppoAandppoC, thus revealing regulatory feedback loops among these three genes. Phylogenetic analyses showed thatppogenes are present in both saprophytic and pathogenic Ascomycetes and Basidiomycetes, suggesting a conserved role for Ppo enzymes in the life cycle of fungi.
Collapse
Affiliation(s)
| | - Terri M Kowieski
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Robert Zarnowski
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Nancy P Keller
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA
| |
Collapse
|
164
|
Mulcahy G, O'Neill S, Fanning J, McCarthy E, Sekiya M. Tissue migration by parasitic helminths – an immunoevasive strategy? Trends Parasitol 2005; 21:273-7. [PMID: 15922248 DOI: 10.1016/j.pt.2005.04.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/04/2005] [Accepted: 04/11/2005] [Indexed: 11/25/2022]
Abstract
Migration through host tissues has major costs for parasitic helminths in terms of energy expenditure, risks of attrition and the need to adapt to varying physicochemical environments. Nevertheless, such migratory phases seem to confer a specific survival advantage. One reason for this might be the avoidance of specific host immune-defence mechanisms designed to protect against threats at mucosal surfaces.
Collapse
Affiliation(s)
- Grace Mulcahy
- Department of Veterinary Microbiology and Parasitology, Faculty of Veterinary Medicine and Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland.
| | | | | | | | | |
Collapse
|
165
|
Abstract
In the nineteenth century, marijuana was prescribed by physicians for maladies ranging from eating disorders to rabies. However, as newer, more effective drugs were discovered and as the potential for abuse of marijuana was recognized, its use as a therapeutic became restricted, and only recently has its therapeutic potential been re-evaluated. Recent studies in animal models and in humans have produced promising results for the treatment of various disorders - such as obesity, cancer, and spasticity and tremor due to neuropathology - with drugs based on marijuana-derived cannabinoids. Moreover, as I discuss here, a wealth of information also indicates that these drugs have immunosuppressive and anti-inflammatory properties; therefore, on the basis of this mode of action, the therapeutic usefulness of these drugs in chronic inflammatory diseases is now being reassessed.
Collapse
Affiliation(s)
- Thomas W Klein
- Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, Tampa, Florida 33612, USA.
| |
Collapse
|
166
|
Abstract
Perturbations in the gastrointestinal (GI) microbiota composition that occur as a result of antibiotics and diet in "westernized" countries are strongly associated with allergies and asthma ("hygiene hypothesis"). The microbiota ("microflora") plays a crucial role in the development of mucosal tolerance, including the airways. Significant attention has been focused on the role of the microbiota in GI development, immune adaptation and initiation of GI inflammatory diseases. This review covers the post-developmental functions that the microbiota plays in regulating immunological tolerance to allergen exposure outside the GI tract and proposes the question: is the microbiota a major regulator of the immune system?
Collapse
Affiliation(s)
- Mairi C Noverr
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-0642, USA
| | | |
Collapse
|
167
|
Noverr MC, Falkowski NR, McDonald RA, McKenzie AN, Huffnagle GB. Development of allergic airway disease in mice following antibiotic therapy and fungal microbiota increase: role of host genetics, antigen, and interleukin-13. Infect Immun 2005; 73:30-8. [PMID: 15618138 PMCID: PMC538952 DOI: 10.1128/iai.73.1.30-38.2005] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Lending support to the hygiene hypothesis, epidemiological studies have demonstrated that allergic disease correlates with widespread use of antibiotics and alterations in fecal microbiota ("microflora"). Antibiotics also lead to overgrowth of the yeast Candida albicans, which can secrete potent prostaglandin-like immune response modulators, from the microbiota. We have recently developed a mouse model of antibiotic-induced gastrointestinal microbiota disruption that is characterized by stable increases in levels of gastrointestinal enteric bacteria and Candida. Using this model, we have previously demonstrated that microbiota disruption can drive the development of a CD4 T-cell-mediated airway allergic response to mold spore challenge in immunocompetent C57BL/6 mice without previous systemic antigen priming. The studies presented here address important questions concerning the universality of the model. To investigate the role of host genetics, we tested BALB/c mice. As with C57BL/6 mice, microbiota disruption promoted the development of an allergic response in the lungs of BALB/c mice upon subsequent challenge with mold spores. In addition, this allergic response required interleukin-13 (IL-13) (the response was absent in IL-13(-/-) mice). To investigate the role of antigen, we subjected mice with disrupted microbiota to intranasal challenge with ovalbumin (OVA). In the absence of systemic priming, only mice with altered microbiota developed airway allergic responses to OVA. The studies presented here demonstrate that the effects of microbiota disruption are largely independent of host genetics and the nature of the antigen and that IL-13 is required for the airway allergic response that follows microbiota disruption.
Collapse
Affiliation(s)
- Mairi C Noverr
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-0642, USA
| | | | | | | | | |
Collapse
|
168
|
Rowley AF, Vogan CL, Taylor GW, Clare AS. Prostaglandins in non-insectan invertebrates: recent insights and unsolved problems. J Exp Biol 2005; 208:3-14. [PMID: 15601872 DOI: 10.1242/jeb.01275] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
SUMMARYProstaglandins (PG) are oxygenated derivatives of C20 polyunsaturated fatty acids including arachidonic and eicosapentaenoic acids. In mammals, these compounds have been shown to play key roles in haemostasis, sleep-wake regulation, smooth muscle tone, and vaso-, temperature and immune regulation. In invertebrates, PGs have been reported to perform similar roles and are involved in the control of oogenesis and spermatogenesis, ion transport and defence. Although there is often a detailed understanding of the actions of these compounds in invertebrates such as insects, knowledge of their mechanism of biosynthesis is often lacking. This account provides a critical review of our current knowledge on the structure and modes of biosynthesis of PGs in invertebrates, with particular reference to aquatic invertebrates. It emphasises some of the most recent findings, which suggest that some PGs have been misidentified.Prostaglandins in invertebrates can be categorised into two main types; the classical forms, such as PGE2 and PGD2 that are found in mammals, and novel forms including clavulones, bromo- and iodo-vulones and various PGA2 and PGE2 esters. A significant number of reports of PG identification in invertebrates have relied upon methods such as enzyme immunoassay that do not have the necessary specificity to ensure the validity of the identification. For example, in the barnacle Balanus amphitrite, although there are PG-like compounds that bind to antibodies raised against PGE2, mass spectrometric analysis failed to confirm the presence of this and other classical PGs. Therefore, care should be taken in drawing conclusions about what PGs are formed in invertebrates without employing appropriate analytical methods. Finally, the recent publication of the Ciona genome should facilitate studies on the nature and mode of biosynthesis of PGs in this advanced deuterostomate invertebrate.
Collapse
Affiliation(s)
- Andrew F Rowley
- School of Biological Sciences, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK.
| | | | | | | |
Collapse
|
169
|
Noverr MC, Noggle RM, Toews GB, Huffnagle GB. Role of antibiotics and fungal microbiota in driving pulmonary allergic responses. Infect Immun 2004; 72:4996-5003. [PMID: 15321991 PMCID: PMC517468 DOI: 10.1128/iai.72.9.4996-5003.2004] [Citation(s) in RCA: 246] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 06/02/2004] [Accepted: 06/16/2004] [Indexed: 11/20/2022] Open
Abstract
Over the past four decades, there has been a significant increase in allergy and asthma in westernized countries, which correlates with alterations in fecal microbiota (microflora) and widespread use of antibiotics (the "hygiene hypothesis"). Antibiotics also lead to overgrowth of the yeast Candida albicans, which can secrete potent prostaglandin-like immune response modulators. We have developed a mouse model of antibiotic-induced microbiota disruption that includes stable increases in gastrointestinal (GI) enteric bacteria and GI Candida levels with no introduction of microbes into the lungs. Mice are treated for 5 days with cefoperazone in the drinking water, followed by a single oral gavage of C. albicans. This results in alterations of GI bacterial populations and increased yeast numbers in the GI microbiota for at least 2 to 3 weeks and can drive the development of a CD4 T-cell-mediated allergic airway response to subsequent mold spore (Aspergillus fumigatus) exposure in immunocompetent mice without previous systemic antigen priming. The allergic response in the lungs is characterized by increased levels of eosinophils, mast cells, interleukin-5 (IL-5), IL-13, gamma interferon, immunoglobulin E, and mucus-secreting cells. In the absence of antibiotics, mice exposed to Aspergillus spores do not develop an allergic response in the airways. This study provides the first experimental evidence to support a role for antibiotics and fungal microbiota in promoting the development of allergic airway disease. In addition, these studies also highlight the concept that events in distal mucosal sites such as the GI tract can play an important role in regulating immune responses in the lungs.
Collapse
Affiliation(s)
- Mairi C Noverr
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-0642, USA
| | | | | | | |
Collapse
|
170
|
Alem MAS, Douglas LJ. Effects of aspirin and other nonsteroidal anti-inflammatory drugs on biofilms and planktonic cells of Candida albicans. Antimicrob Agents Chemother 2004; 48:41-7. [PMID: 14693516 PMCID: PMC310207 DOI: 10.1128/aac.48.1.41-47.2004] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prostaglandins are now known to be produced by Candida albicans and may play an important role in fungal colonization. Their synthesis in mammalian cells is decreased by inhibitors of the cyclooxygenase isoenzymes required for prostaglandin formation. In the present study, a catheter disk model system was used to investigate the effects of nonsteroidal anti-inflammatory drugs (all cyclooxygenase inhibitors) on biofilm formation by three strains of C. albicans. Seven of nine drugs tested at a concentration of 1 mM inhibited biofilm formation. Aspirin, etodolac, and diclofenac produced the greatest effects, with aspirin causing up to 95% inhibition. Celecoxib, nimesulide, ibuprofen, and meloxicam also inhibited biofilm formation, but to a lesser extent. Aspirin was active against growing and fully mature (48-h) biofilms; its effect was dose related, and it produced significant inhibition (20 to 80%) at pharmacological concentrations. Simultaneous addition of prostaglandin E(2) abolished the inhibitory effect of 25 or 50 micro M aspirin. At 1 mM, aspirin reduced the viability of biofilm organisms to 1.9% of that of controls. Surviving cells had a wrinkled appearance, as judged by scanning electron microscopy, and consisted of both yeasts and hyphae. Treatment with other cyclooxygenase inhibitors, such as etodolac, resulted in biofilms that consisted almost entirely of yeast cells. In conventional assays for germ tube formation, these drugs produced significant inhibition, whereas aspirin had little effect. Our findings suggest that cyclooxygenase-dependent synthesis of fungal prostaglandin(s) is important for both biofilm development and morphogenesis in C. albicans and may act as a regulator in these physiological processes. Our results also demonstrate that aspirin possesses potent antibiofilm activity in vitro and could be useful in combined therapy with conventional antifungal agents in the management of some biofilm-associated Candida infections.
Collapse
Affiliation(s)
- Mohammed A S Alem
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | | |
Collapse
|
171
|
Huffnagle GB, Deepe GS. Innate and adaptive determinants of host susceptibility to medically important fungi. Curr Opin Microbiol 2003; 6:344-50. [PMID: 12941402 DOI: 10.1016/s1369-5274(03)00089-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The host response is the outcome of an interplay between innate immunity, adaptive immunity (Th1, Th2, T regulatory cells, B cells and antibodies) and fungal virulence factors. Dendritic cells are the gatekeepers between innate and adaptive immunity and have been the intense focus of recent studies on innate immunity to fungi because of their ability to distinguish between different forms of a fungal species, to drive Th1 versus Th2 versus T regulatory responses, and potentially be modulated by fungal products. New mechanisms have been described by which anti-fungal antibodies can modulate infection and augment T cell immunity. Th1 responses are central to limiting infection with many fungi; thus, a great deal of attention has been focused recently on the antigen(s) that trigger such a response.
Collapse
Affiliation(s)
- Gary B Huffnagle
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Michigan, Ann Arbor, MI 48109-0642, USA.
| | | |
Collapse
|