Journal of leukocyte biology
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θ-Defensins are pleiotropic, macrocyclic peptides that are expressed uniquely in Old World monkeys. The peptides are potent, broad-spectrum microbicides that also modulate inflammatory responses in vitro and in animal models of viral infection and polymicrobial sepsis. θ-Defensins suppress proinflammatory cytokine secretion by leukocytes stimulated with diverse Toll-like receptor (TLR) ligands. Studies were performed to delineate anti-inflammatory mechanisms of rhesus θ-defensin 1 (RTD-1), the most abundant θ-defensin isoform in macaque granulocytes. ⋯ RTD-1 inhibited IκBα degradation and p38 MAPK phosphorylation, and stimulated Akt phosphorylation in LPS-treated human primary monocytes and THP-1 macrophages. Specific inhibition of phosphatidylinositol 3-kinase (PI3K) blocked RTD-1-stimulated Akt phosphorylation and reversed the suppression of NF-κB activation by the peptide. These studies indicate that the anti-inflammatory properties of θ-defensins are mediated by activation of the PI3K/Akt pathway and suppression of proinflammatory signals in immune-stimulated cells.
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Comparative Study
STAT5 phosphorylation in T cell subsets from septic patients in response to recombinant human interleukin-7: a pilot study.
Septic shock is characterized by lymphocyte alterations associated with increased risk of nosocomial infections and mortality. IL-7, a cytokine required for T cell survival, is thought as a novel therapy for septic patients with severe lymphopenia. We assessed CD4(+) lymphocyte responsiveness to rhIL-7 in septic shock patients ex vivo. ⋯ Importantly, low doses of rhIL-7 preferentially activated Teff versus Treg in patients and nonsurvivors tended to present with decreased pSTAT5 expression. This pilot study is the first to highlight, in septic patients, the interest of pSTAT5 measurement in whole blood for the monitoring of rhIL-7 therapy. Such a method could represent an innovative, biologic tool for monitoring leukocyte pharmacological responses to biotherapies in daily clinical practice in other clinical contexts.
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This study tested the hypothesis that besides the spleen, LNs, peripheral blood, and thymus contain a regulatory IL-10-producing CD19(+)CD5(+)CD1d(high) B cell subset that may play a critical role in the maintenance of immune homeostasis. Indeed, this population was identified in the murine thymus, and furthermore, when cocultured with CD4(+) T cells, this population of B cells supported the maintenance of CD4(+)Foxp3(+) Tregs in vitro, in part, via the CD5-CD72 interaction. Mice homozygous for Cd19(Cre) (CD19(-/-)) express B cells with impaired signaling and humoral responses. ⋯ Consistent with these results, transfer of thymic CD19(+)CD5(+)CD1d(hi) B cells into CD19(-/-) mice resulted in significantly up-regulated numbers of CD4(+)Foxp3(+) Tregs with a concomitant reduction in CD4(+)CD8(-) and CD4(-)CD8(+) T cell populations in the thymus, spleen, and LNs but not in the BM of recipient mice. In addition, thymic CD19(+)CD5(+)CD1d(hi) B cells significantly suppressed autoimmune responses in lupus-like mice via up-regulation of CD4(+)Foxp3(+) Tregs and IL-10-producing Bregs. This study suggests that thymic CD19(+)CD5(+)CD1d(hi)IL-10(+) Bregs play a critical role in the maintenance of immune homeostasis.
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Conventional wisdom presumes that the α7nAChR product of CHRNA7 expression mediates the ability of the vagus nerve to regulate the inflammatory response to injury and infection. Yet, 15 years ago, a 2nd structurally distinct and human-specific α7nAChR gene was discovered that has largely escaped attention of the inflammation research community. The gene, originally called dupα7nAChR but now known as CHRFAM7A, has been studied exhaustively in psychiatric research because of its association with mental illness. ⋯ Because of its potential for the injury research community, its possible significance to human leukocyte biology, and its relevance to human inflammation, we review the discovery and structure of the dupα7nAChR/CHRFAM7A gene, the distribution of its mRNA, and its biologic activities and then discuss its possible role(s) in specifying human inflammation and injury. In light of emerging concepts that point to a role for human-specific genes in complex human disease, the existence of a human-specific α7nAChR regulating inflammatory responses in injury underscores the need for caution in extrapolating findings in the α7nAChR literature to man. To this end, we discuss the translational implications of a uniquely human α7nAChR-like gene on new drug target discovery and therapeutics development for injury, infection, and inflammation.
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The causative microorganisms dictate the type of MDSC generated in sepsis patients, and a large proportion of PMN-MDSCs in gram-positive sepsis includes immunosuppressive myeloid blasts. MDSCs constitute a heterogeneous population of immature myeloid cells that potently suppress immune responses. They were identified originally in cancer patients and have since been reported to occur also in chronic inflammation, autoimmunity, and even bacterial infections. ⋯ We found a high frequency of typical CD14(+)HLA-DR(low) Mo-MDSCs in all sepsis patients, whereas the typical PMN-MDSCs, as well as a prominent CD14(low) PMN-MDSC-like population, appeared preferentially in gram-positive cases. The CD14(low) PMN-MDSC variant was demonstrated to suppress T cell proliferation in vitro via a ROS-dependent mechanism, to display an increased IL-10:TNF-α ratio, and to present with signs of immaturity: blast morphology and low cytokine levels. We conclude that a spectrum of cells with MDSC features is enriched in sepsis and that the microbial origin of sepsis contributes to the substantial interindividual patient variation in the MDSC pattern.