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PubMed1987

Neuropeptides modulating macrophage function.

The immune system and the neuroendocrine system affect each other via molecules and receptors shared by both systems. Neuroendocrine hormones may act either positively or negatively in regulating the activities of a key cell of the immune system, the macrophage. For example, adenocorticotropic hormone (ACTH), somatostatin, and substance P are all capable of increasing the cytotoxicity of macrophages against tumor cells. However, ACTH and somatostatin, but not substance P, can also block the tumoricidal activity of macrophages induced by recombinant gamma interferon (IFN-gamma), a non-neuroendocrine immunomodulating hormone. In contrast, substance P increased tumoricidal activity, both independent of IFN-gamma and in addition to IFN-gamma. Neurotensin, alpha-endorphin, beta-endorphin, met-enkephalin, vasopressin, and substance K did not affect tumoricidal function, either alone or in combination with IFN-gamma. Substance P, but not the other neuropeptides, increased substantially the proportion of macrophages able to secrete superoxide ions, suggesting a possible influence on macrophage capacity to deal with microbial infection. Such positive and negative modulation of macrophage effector functions could contribute to the influence of cognitive stimuli in infection and neoplasia.

Adjuvants, Immunologic↗
PubMed1989

Genetic profile of a nalidixic acid analog: a model for the mechanism of sister chromatid exchange induction.

In recent years, evidence has accumulated that suggests that mammalian topoisomerase may play a role in the formation of spontaneous or chemically induced sister chromatid exchange (SCE). In microbial systems, nalidixic acid is known to disrupt the function of a topoisomerase-like enzyme, DNA gyrase. To explore the possible relationship to topoisomerase function and SCE formation in mammalian cells, an analog of nalidixic acid with potent topoisomerase II inhibitory activity was selected for examination in a variety of genetic toxicology assays. This analog, CP-67,015, proved to be a positive direct-acting mutagen in the L5178Y/TK+/-, CHO/HGPRT, and V79/HGPRT systems. However, no gene mutational activity was observed using the Ames test in direct plate, mouse and rat metabolic activation, and mouse urine tests. In vitro cytogenetic studies showed strong clastogenic activity in human lymphocytes and in CHO cells. Compound-induced chromosome damage was also observed in vivo in mouse bone marrow cells. Surprisingly, SCE studies in vitro in human lymphocytes or CHO cells showed only slight increases, even at levels producing severe chromosome breakage. Mouse bone marrow showed no significant elevation of SCE following parenteral treatment with CP-67,015. These results, taken together, demonstrate that CP-67,015 is a direct-acting mutagen in mammalian cells with both gene and chromosomal level effects. The relative ineffectiveness in producing SCEs suggests that CP-67,015 may interfere with a DNA replicative/repair process, perhaps by alteration of one or more DNA polymerase activities. This suggestion is based in part on the known effect of the analog nalidixic acid on DNA gyrase in microbial cells and on topoisomerase in mammalian cells. The profile of genetic activity of CP-67,015, coupled with its inhibitory effect on topoisomerase function, gives rise to a model for SCE formation that is based on anomalies of topoisomerase activity during DNA synthesis.

4-Quinolones↗
PubMed2026

Oral bacteriome in pediatric patients with malignancies prior to chemotherapy: a pilot study using full-length 16S rRNA sequencing.

OBJECTIVE: To characterize the composition, diversity, and ecological features of the oral bacteriome in pediatric patients with malignancies prior to chemotherapy initiation. METHODS: In this prospective pilot study,supragingival plaque samples were collected from 10 pediatric cancer patients prior to the initiation of chemotherapy. Bacterial genomic DNA was extracted from each sample, and the full-length 16S rRNA gene was amplified and sequenced on the PacBio Sequel II platform using circular consensus sequencing (CCS). Raw CCS reads were quality-filtered and denoised into amplicon sequence variants (ASVs) using DADA2, and taxonomic assignment was performed against the SILVA 138 reference database. Alpha diversity was assessed using the Chao1, Shannon, Simpson, and Faith's phylogenetic diversity (PD whole tree) indices, while beta diversity was evaluated through principal coordinate analysis (PCoA), and non-metric multidimensional scaling (NMDS). Microbial co-occurrence networks were constructed to characterize bacterial interactions, and functional potential was predicted using PICRUSt2, and BugBase. RESULTS: A total of 614,473 high-quality CCS reads were generated, yielding 1,697 ASVs. Alpha diversity analysis revealed substantial inter-individual variation in microbial richness and diversity among the pediatric cancer patients. The bacterial community was dominated by the phyla Firmicutes, Proteobacteria, Bacteroidota, Actinobacteriota. At the genus level, Streptococcus, Prevotella, Neisseria, and Haemophilus were the most abundant taxa. Beta diversity analysis revealed distinct clustering patterns, indicating highly individualized microbial profiles. Co-occurrence network analysis identified several keystone taxa and potential pathogenic associations within the supragingival plaque community. Functional prediction indicated that the dominant metabolic pathways were related to amino acid metabolism, carbohydrate metabolism, and membrane transport. CONCLUSION: These preliminary findings reveal a taxonomically diverse, highly individualized pre-chemotherapy oral bacteriome, providing foundational baseline profiles to guide future longitudinal investigations of chemotherapy-induced dysbiosis and personalized interventions.

Humans↗
PubMed2000

Nuclear factor-kappa B activation and innate immune response in microbial pathogen infection.

Human pathogenic microorganisms have developed a variety of strategies to infect the host organism successfully, whereas the host has evolved a series of defense mechanisms. In most cases, the epithelial cell layer represents the first barrier for the bacterial pathogen and triggers the innate and inflammatory responses in the host. Epithelial cells release proinflammatory mediators including cytokines and chemokines, leading to the subsequent attraction of monocytes/macrophages. Therefore, epithelial cells represent an immediate-early warning system in the host organism. Subsequent to the colonization of the epithelial layer, invasive microbial pathogens often induce an acute inflammatory response, which functions to activate residential macrophages and recruits blood leukocytes to the site of infection. Distinct receptors of the Toll family on the cell surface of immune cells mediate antibacterial responses in mammals as well as in Drosophila. One of the most important cellular factors involved in the regulation of the host innate antimicrobial response is the immediate-early response transcription factor nuclear factor (NF)-kappa B. Microbial pathogens activate cellular signal transduction pathways that induce NF-kappa B activation, but pathogens also find ways to overcome the innate immune response through active manipulation of the NF-kappa B signal transduction pathways. Exploration of the mechanisms that influence NF-kappa B activity could contribute to a better understanding of the molecular pathogenesis of microbial infections and could be important for potential therapeutic intervention that may be relevant in a wide variety of inflammatory diseases.

Animals↗
PubMed1998

Pilus biogenesis via the chaperone/usher pathway: an integration of structure and function.

The molecular basis of how pathogenic bacteria cause disease has been studied by blending a well-developed genetic system with X-ray crystallography, protein chemistry, high resolution electron microscopy, and cell biology. Microbial attachment to host tissues is one of the key events in the early stages of most bacterial infections. Attachment is typically mediated by adhesins that are assembled into hair-like fibers called pili on bacterial surfaces. This article focuses on the structure-function correlates of P pili, which are produced by most pyelonephritic strains of Escherichia coli. P pili are assembled via a chaperone/usher pathway. Similar pathways are responsible for the assembly of over 30 adhesive organelles in various Gram-negative pathogens. P pilus biogenesis has been used as a model system to elucidate common themes in bacterial pathogenesis, namely, the protein folding, secretion, and assembly of virulence factors. The structural basis for pilus biogenesis is discussed as well as the function and consequences of microbial attachment.

Amino Acid Sequence↗
PubMed2003

Pharmaceuticals, direct-fed microbials, and enzymes for enhancing growth and feed efficiency of beef.

This article provides a brief review of the types of products commonly used in one or more countries of North America to enhance the performance of growing beef cattle. Performance-enhancing products primarily target metabolism (e.g., anabolic implants, zilpaterol, and melengestrol acetate) or gut function (e.g., ionophores, low-level antibiotics, direct-fed microbials, and enzymes). Using currently available performance-enhancing products, rate and efficiency of growth typically are improved from 5% to 20% and 3% to 10%, respectively.

Animal Feed↗
PubMed2002

Microbial alkaline pectinases and their industrial applications: a review.

The biotechnological potential of pectinolytic enzymes from microorganisms has drawn a great deal of attention from various researchers worldwide as likely biological catalysts in a variety of industrial processes. Alkaline pectinases are among the most important industrial enzymes and are of great significance in the current biotechnological arena with wide-ranging applications in textile processing, degumming of plant bast fibers, treatment of pectic wastewaters, paper making, and coffee and tea fermentations. The present review features the potential applications and uses of microbial alkaline pectinases, the nature of pectin, and the vast range of pectinolytic enzymes that function to mineralize pectic substances present in the environment. It also emphasizes the environmentally friendly applications of microbial alkaline pectinases thereby revealing their underestimated potential. The review intends to explore the potential of these enzymes and to encourage new alkaline pectinase-based industrial technology.

Bacteria↗
PubMed2024

A metabolomics pipeline highlights microbial metabolism in bloodstream infections.

The growth of antimicrobial resistance (AMR) highlights an urgent need to identify bacterial pathogenic functions that may be targets for clinical intervention. Although severe infections profoundly alter host metabolism, prior studies have largely ignored microbial metabolism in this context. Here, we describe an iterative, comparative metabolomics pipeline to uncover microbial metabolic features in the complex setting of a host and apply it to investigate gram-negative bloodstream infection (BSI) in patients. We find elevated levels of bacterially derived acetylated polyamines during BSI and discover the enzyme responsible for their production (SpeG). Blocking SpeG activity reduces bacterial proliferation and slows pathogenesis. Reduction of SpeG activity also enhances bacterial membrane permeability and increases intracellular antibiotic accumulation, allowing us to overcome AMR in culture and in vivo. This study highlights how tools to study pathogen metabolism in the natural context of infection can reveal and prioritize therapeutic strategies for addressing challenging infections.

Metabolomics↗
PubMed2006

The Wingless homolog WNT5A and its receptor Frizzled-5 regulate inflammatory responses of human mononuclear cells induced by microbial stimulation.

Microarray--assisted gene--expression screens of human macrophages revealed WNT5A, a homolog of Wingless, a key regulator of Drosophila melanogaster embryonic segmentation and patterning, to be consistently up-regulated following stimulation with different mycobacterial species and conserved bacterial structures. The expression of WNT5A required Toll-like receptor signaling and NF-kappaB activation, which identifies a novel induction pathway for a Wingless homolog. We show that human peripheral-blood mononuclear cells express the WNT5A receptor Frizzled-5 (FZD5). Both WNT5A and FZD5 also were detected in granulomatous lesions in the lungs of Mycobacterium tuberculosis-infected patients. Functional studies showed that WNT5A and FZD5 regulate the microbially induced interleukin-12 response of antigen-presenting cells and interferon-gamma production by mycobacterial antigen-stimulated T cells. Our findings implicate the evolutionarily conserved WNT/Frizzled signaling system in bridging innate and adaptive immunity to infections.

Antigen-Presenting Cells↗
PubMed2002

Evolution of glycosaminoglycans and their glycosyltransferases: Implications for the extracellular matrices of animals and the capsules of pathogenic bacteria.

Glycosaminoglycans (linear polysaccharides with a repeating disaccharide backbone containing an amino sugar) are essential components of extracellular matrices of animals. These complex molecules play important structural, adhesion, and signaling roles in mammals. Direct detection of glycosaminoglycans has been reported in a variety of organisms, but perhaps more definitive tests for the glycosyltransferase genes should be utilized to clarify the distribution of glycosaminoglycans in metazoans. Recently, glycosyltransferases that form the hyaluronan, heparin/heparan, or chondroitin backbone were identified at the molecular level. The three types of glycosyltransferases appear to have evolved independently based on sequence comparisons and other characteristics. All metazoans appear to possess heparin/heparan. Chondroitin is found in some worms, arthropods, and higher animals. Hyaluronan is found only in two of the three main branches of chordates. The presence of several types of glycosaminoglycans in the body allows multiple communication channels and adhesion systems to operate simultaneously. Certain pathogenic bacteria produce extracellular coatings, called capsules, which are composed of glycosaminoglycans that increase their virulence during infection. The capsule helps shield the microbe from the host defenses and/or modulates host physiology. The bacterial and animal polysaccharides are chemically identical or at least very similar. Therefore, no immune response is generated, in contrast to the vast majority of capsular polymers from other bacteria. In microbial systems, it appears that in most cases functional convergent evolution of glycosaminoglycan glycosyltransferases occurred, rather than direct horizontal gene transfer from their vertebrate hosts.

Amino Acid Sequence↗
PubMed1997

NKR-P1A protein, an activating receptor of rat natural killer cells, binds to the chitobiose core of uncompletely glycosylated N-linked glycans, and to linear chitooligomers.

NKR-P1 represent a family of activating receptors in rodent natural killer cells related to C-type animal lectins. We identify here the elements involved in the reactivity of the major receptor of rat, NKR-P1A, with N-linked oligosaccharides of glycoproteins. Plate inhibition assays with isolated, structurally defined N-glycans as inhibitors of binding of NKR-P1A to GlcNAc16-BSA revealed that the removal of both the external sialic acids and the penultimate galactose residues resulted in attaining of significant inhibitory activities. Surprisingly, additional plate inhibition and glycoprotein overlay experiments brought evidence that the core chitobiose, depending on its substitution, can per se support the interaction with NKR-P1A. In a series of linear chitooligomers (n = 2-7), the inhibitory activities reached a maximum for the chitotetraose. The ability of NKR-P1 to recognize both the periphery and the core region of complex type oligosaccharides may define its dual specificity towards carbohydrate components of eukaryotic (e.g., tumor) cell surfaces, but also reflect an evolutionarily conserved reactivity with microbial saccharides important in immune recognition and signaling functions.

Animals↗
PubMed1975

Evidence for the activation of 3-methylcholanthrene as a carcinogen in vivo and asa mutagen in vitro by P1 -450 from inbred strains of mice.

Genetic differences in aromatic hydrocarbon "responsiveness" exist among various mouse strains. New formation of cytochrome P1-450 and the induction aryl hydrocarbon (benzo [a ])pyrene) hydroxylase (as well as numerous other monooxygenase activities) appear to be associated ultimately with genes that cosegregate at a small number of genetic loci. By comparing "responsive" and "nonresponsive" siblings, we can evaluate the susceptibility of each individual to various mutagenic chemicals in vitro or carcinogenic agents in vivo.

Animals↗
PubMed2002

TLR4 as the mammalian endotoxin sensor.

For more than a century, the ability to sense endotoxin (later known also as lipopolysaccharide; LPS) stood as the archetypal innate immune response: even before the phrase 'innate immunity' became popular. Yet the mechanism by which LPS initiated a signal remained unknown. The problem was solved in 1998 by positional cloning, which revealed that Toll-like receptor (TLR) 4, one of ten mammalian paralogues with homology to the Drosophila protein Toll, is the central component of the LPS receptor. During the 3 years that followed, gene knockout work supported the view that the TLRs perceive a number of indispensable molecular structures shared by diverse representatives of the microbial world. The highly specific LPS-sensing function of TLR4 is remarkable for its prevalence in Mammalia, which to the present time is the only class of the phylum Chordata known to have a gene encoding TLR4, and known to display exquisite sensitivity to LPS. The fact that LPS signals are elicited through a single biochemical pathway has raised important pharmacotherapeutic opportunities as well.

Animals↗
PubMed1987

Preliminary studies on the inflammatory stimulus induced proteins in mouse resident peritoneal macrophages.

Chemotaxis, release of lysosomal enzymes, synthesis of eicosanoids and phagocytosis are some of the important functions mediated by macrophages. Active protein synthesis have been implicated as an essential step in the mediation of these vital physiological functions. The proteins synthesized during the inflammation with microbial agents have not been identified. In the current investigation, we report the synthesis of five proteins of molecular weights 72,000; 70,000; 40,000; 34,000; and 32,000 in mouse peritoneal macrophages after incubation with inflammatory stimuli derived from microorganisms. A possible role for these proteins in phagocytosis was suggested.

Animals↗
PubMed2002

Metabolic engineering towards biotechnological production of carotenoids in microorganisms.

Carotenoids are important natural pigments produced by many microorganisms and plants. Traditionally, carotenoids have been used in the feed, food and nutraceutical industries. The recent discoveries of health-related beneficial properties attributed to carotenoids have spurred great interest in the production of structurally diverse carotenoids for pharmaceutical applications. The availability of a considerable number of microbial and plant carotenoid genes that can be functionally expressed in heterologous hosts has opened ways for the production of diverse carotenoid compounds in heterologous systems. In this review, we will describe the recent progress made in metabolic engineering of non-carotenogenic microorganisms for improved carotenoid productivity. In addition, we will discuss the application of combinatorial and evolutionary strategies to carotenoid pathway engineering to broaden the diversity of carotenoid structures synthesized in recombinant hosts.

Bacteria↗
PubMed1994

Chemokine receptors and molecular mimicry.

Chemokines are small pro-inflammatory peptides that are best known for their leukocyte-chemoattractant activity. The cloned leukocyte chemokine receptors, interleukin 8 receptor (IL-8R) types A and B and the macrophage inflammatory protein 1 alpha (MIP-1 alpha)/RANTES receptor, are related by sequence and chemokine binding to two herpesvirus products, and to the Duffy antigen that mediates erythrocyte invasion by the malaria-causing parasite Plasmodium vivax. Here, Sunil Ahuja, Ji-Liang Gao and Philip Murphy suggest that, in addition to the activation of leukocytes, chemokines may be important in the function of erythrocytes and, through molecular mimicry, in microbial pathogenesis.

Animals↗