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Host Innate Immune System (host + innate_immune_system)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Identification, structure and differential expression of novel pleurocidins clustered on the genome of the winter flounder, Pseudopleuronectes americanus (Walbaum)

FEBS JOURNAL, Issue 18 2003
Susan E. Douglas
Antimicrobial peptides form one of the first lines of defense against invading pathogens by killing the microorganisms and/or mobilizing the host innate immune system. Although over 800 antimicrobial peptides have been isolated from many different species, especially insects, few have been reported from marine fish. Sequence analysis of two genomic clones (15.6 and 12.5 kb) from the winter flounder, Pseudopleuronectes americanus (Walbaum) resulted in the identification of multiple clustered genes for novel pleurocidin-like antimicrobial peptides. Four genes and three pseudogenes (,) are encoded in these clusters, all of which have similar intron/exon boundaries but specify putative antimicrobial peptides differing in sequence. Pseudogenes are easily detectable but have incorrect initiator codons (ACG) and often contain a frameshift(s). Potential promoters and binding sites for transcription factors implicated in regulation of expression of immune-related genes have been identified in upstream regions by comparative genomics. Using reverse transcription-PCR assays, we have shown for the first time that each gene is expressed in a tissue-specific and developmental stage-specific manner. In addition, synthetic peptides based on the sequences of both genes and pseudogenes have been produced and tested for antimicrobial activity. These data can be used as a basis for prediction of antimicrobial peptide candidates for both human and nonhuman therapeutants from genomic sequences and will aid in understanding the evolution and transcriptional regulation of expression of these peptides. [source]

Alcohol Suppresses IL-2,Induced CC Chemokine Production by Natural Killer Cells

ALCOHOLISM, Issue 9 2005
Ting Zhang
Background: Natural killer (NK) cells are a critical component of the host innate immune system. We investigated whether alcohol impairs NK cell function, particularly production of CC chemokines induced by interleukin (IL)-2, the natural ligands for CCR5 receptor. Methods: Primary NK cells and NK cell line (YTS) were cultured with or without alcohol (10 to 80 mM) for three hours. The culture supernatants were then harvested and used to treat human peripheral blood monocyte-derived macrophages and a HeLa cell line, which expresses CD4, CCR5, and CXCR4 receptors (MAGI cells). CC chemokine expression by YTS and primary NK cells treated with or without alcohol was analyzed with the real-time RT-PCR and ELISA. Ca2+i and Western blot assays were used to determine calcium-mediated intracellular signaling pathway and NF-,B p65 expression. HIV strains (Bal and UG024) were used to infect macrophages and MAGI cells. In addition, ADA (macrophage-tropic strain) and murine leukemia virus (MLV) envelope-pseudotyped HIV infection was carried out in macrophages. HIV infectivity was determined by HIV reverse transcriptase (RT) and ,-galactosidase activity assays. Results: Alcohol inhibited IL-2,induced CC chemokine (CCL3 and CCL4) expression by NK cells. Functional tests demonstrated that this reduced expression of CC chemokines was associated with diminished anti-HIV ability of NK cells. Alcohol also reduced the ability of NK cells to response to CCL3-mediated chemotaxis. Alcohol inhibited IL-2,induced NF-,B p65 protein expression and calcium mobilization by NK cells. Conclusions: Alcohol, through the inhibition of IL-2,induced NF-,B p65 protein expression and intracellular calcium mobilization, suppressed NK cell production of CC chemokines. This suppression of CC chemokine production was associated with diminished anti-HIV activity of NK cells. Thus, by inhibiting NK cell,mediated innate immunity against HIV, alcohol consumption may have a cofactor role in the immunopathogenesis of HIV disease. [source]

Hericium erinaceum induces maturation of dendritic cells derived from human peripheral blood monocytes

PHYTOTHERAPY RESEARCH, Issue 1 2010
Sun Kyung Kim
Abstract Hericium erinaceum, a medicinal mushroom, has long been used as a therapeutic due to its immuno-regulating potentials eliciting anticarcinogenic and antimicrobial efficacies. Since maturation of dendritic cells (DC) is an important process in the initiation and regulation of immune responses, the ability of water-soluble components from H. erinaceum (WEHE) to regulate DC maturation was investigated. Immature DC were prepared by differentiating human peripheral blood CD14-positive cells with GM-CSF and IL-4. DC were stimulated with WEHE at 2,20 µg/mL for 48 h and subjected to flow cytometric analysis to determine the expression of indicative maturation markers. The endocytic capacity of WEHE-stimulated DC was examined by a Dextran-FITC uptake assay. An enzyme-linked immunosorbent assay was performed to examine the secretion of TNF- , and IL-12p40. DC stimulated with WEHE showed representative features upon DC maturation: enhanced expression of CD80, CD83 and CD86, and both MHC class I and II molecules, decreased endocytic capacity of DC, increased expression of CD205, and decreased expression of CD206. However, interestingly, WEHE could not induce the production of TNF- , and IL-12p40, whereas lipopolysaccharide substantially increased the production of both cytokines. Collectively, these results suggest that H. erinaceum induces the maturation of human DC, which might reinforce the host innate immune system. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Functional basis for complement evasion by staphylococcal superantigen-like 7

CELLULAR MICROBIOLOGY, Issue 10 2010
Jovanka Bestebroer
Summary The human pathogen Staphylococcus aureus has a plethora of virulence factors that promote its colonization and survival in the host. Among such immune modulators are staphylococcal superantigen-like (SSL) proteins, comprising a family of 14 small, secreted molecules that seem to interfere with the host innate immune system. SSL7 has been described to bind immunoglobulin A (IgA) and complement C5, thereby inhibiting IgA-Fc,RI binding and serum killing of Escherichia coli. As C5a generation, in contrast to C5b-9-mediated lysis, is crucial for immune defence against staphylococci, we investigated the impact of SSL7 on staphylococcal-induced C5a-mediated effects. Here, we show that SSL7 inhibits C5a generation induced by staphylococcal opsonization, slightly enhanced by its IgA-binding capacity. Moreover, we demonstrate a strong protective activity of SSL7 against staphylococcal clearance in human whole blood. SSL7 strongly inhibited the C5a-induced phagocytosis of S. aureus and oxidative burst in an in vitro whole-blood inflammation model. Furthermore, we found that SSL7 affects all three pathways of complement activation and inhibits the cleavage of C5 by interference of its binding to C5 convertases. Finally, SSL7 effects were also demonstrated in vivo. In a murine model of immune complex peritonitis, SSL7 abrogated the C5a-driven influx of neutrophils in mouse peritoneum. [source]