Reduced bioenergetics and toll-like receptor 1 function in human polymorphonuclear leukocytes in aging.

Aging is associated with a progressive decline in immune function (immunosenescence) resulting in an increased susceptibility to viral and bacterial infections. Here we show reduced expression of Toll-like receptor 1 (TLR1) in polymorphonuclear leukocytes (PMN) and an underlying age-dependent deficiency in PMN bioenergetics. In older (>65 years) adults, stimulation through TLR1 led to lower activation of integrins (CD11b and CD18), lower production of the chemokine IL-8, and lower levels of the phosphorylated signaling intermediate p38 MAP kinase than in PMN from younger donors (21-30 years).

Plunder of Human Blood Leukocytes Containing Ingested Material, by Other Leukocytes: Where Is the Fusagen That Allows Preservation of Membrane Integrity and Motile Function?

In studying phagocytosis of zymosan particles by human blood monocytes in phase-contrast videomicroscopy, we found that monocytes loaded with zymosan particles became chemotactic for polymorphonuclear leukocytes (PMN) which closed on them and purloined their particle content. This despoliation usually occurred in monocytes that had begun to swell-prefiguring their death. The violent seizure of their contents by the aggressing PMN often tore the monocytes apart.

Infection-induced NETosis is a dynamic process involving neutrophil multitasking in vivo.

Neutrophil extracellular traps (NETs) are released as neutrophils die in vitro in a process requiring hours, leaving a temporal gap that invasive microbes may exploit. Neutrophils capable of migration and phagocytosis while undergoing NETosis have not been documented. During Gram-positive skin infections, we directly visualized live polymorphonuclear cells (PMNs) in vivo rapidly releasing NETs, which prevented systemic bacterial dissemination.

Inflammatory gout: observations over a half-century.

This is a discussion of acute gouty arthritis, seen for over 50 years of engagement. It addresses the evolution of our current understanding of the interaction between urate crystals and key cellular components of the gouty inflammatory paroxysm, with new material on pathogenesis.

Anaplasma phagocytophilum induces actin phosphorylation to selectively regulate gene transcription in Ixodes scapularis ticks.

Anaplasma phagocytophilum, the agent of human anaplasmosis, persists in ticks and mammals. We show that A. phagocytophilum induces the phosphorylation of actin in an Ixodes ricinus tick cell line and Ixodes scapularis ticks, to alter the ratio of monomeric/filamentous (G/F) actin.

Increased TLR4 expression and downstream cytokine production in immunosuppressed adults compared to non-immunosuppressed adults.

Background: An increasing number of patients have medical conditions with altered host immunity or that require immunosuppressive medications. While immunosuppression is associated with increased risk of infection, the precise effect of immunosuppression on innate immunity is not well understood. We studied monocyte Toll-like receptor (TLR) expression and cytokine production in 137 patients with autoimmune diseases who were maintained on immunosuppressive medications and 419 non-immunosuppressed individuals.

Tonic inhibition of chemotaxis in human plasma.

We found exaggerated chemotaxis in plasma treated with EDTA and thought that the EDTA might itself be inhibiting a tonic inhibitor(s) of chemotaxis. Our plasma fractionations suggested that evidence should be sought for a lipid moiety carrying this activity, and on spectrometry (LC-MS-MS together with GC-MS analyses), the biologically active but not the inactive fraction contained oleic and arachidonic acids. Because fatty acids are largely protein bound, we flooded plasma preparations with delipidated albumin, reasoning that it would bind enough fatty acids, including inhibitory ones, to counter their tonic inhibition.

Dysregulation of TLR3 impairs the innate immune response to West Nile virus in the elderly.

West Nile virus (WNV), a mosquito-borne flavivirus, has recently emerged in North America, and the elderly are particularly susceptible to severe neurological disease and death from infection with this virus. We have investigated the innate immune response of primary human macrophages to WNV in vitro and have found significant differences between the responsiveness of macrophages derived from younger donors and that from older donors. Binding of the glycosylated WNV envelope protein to the C-type lectin dendritic cell-specific intercellular adhesion molecule 3 (ICAM3) grabbing nonintegrin (DC-SIGN) leads to a reduction in the expression of Toll-like receptor 3 (TLR3) in macrophages from young donors via the signal transducer and activator of transcription 1 (STAT1)-mediated pathway.

Clocking the Lyme spirochete.

In order to clear the body of infecting spirochetes, phagocytic cells must be able to get hold of them. In real-time phase-contrast videomicroscopy we were able to measure the speed of Borrelia burgdorferi (Bb), the Lyme spirochete, moving back and forth across a platelet to which it was tethered. Its mean crossing speed was 1,636 microm/min (N = 28), maximum, 2800 microm/min (N = 3).

Phagocytic function of human blood polymorphonuclear leukocytes in the presence of carrageenan, a potential vaginal microbicide.

Carrageenan is currently undergoing clinical trials as the active constituent of a vaginal gel product for use as a female-controlled option to prevent the transmission of HIV during sexual intercourse. Here we show that in the presence of 0.5 mg/ml of carrageenan, human blood polymorphonuclear leukocytes (PMN) do not ingest this material, as evidenced by a lack of progressive vacuolization, but can ingest microorganisms present in the medium, excluding adjacent carrageenan.

Recruitment of macrophages and polymorphonuclear leukocytes in Lyme carditis.

Lyme arthritis, caused by the spirochete Borrelia burgdorferi, can be recurrent or prolonged, whereas Lyme carditis is mostly nonrecurring. A prominent difference between arthritis and carditis is the differential representation of phagocytes in these lesions: polymorphonuclear leukocytes (PMN) are more prevalent in the joint, and macrophages predominate in the heart lesion. We have previously shown differential efficiency of B.

Human neutrophil calprotectin reduces the susceptibility of Borrelia burgdorferi to penicillin.

Borrelia burgdorferi, the spirochetal agent of Lyme disease, is susceptible to killing by a variety of polymorphonuclear leukocyte (PMN) components. Some are most effective against metabolically active B. burgdorferi.

Cryopreservable neutrophil surrogates: granule-poor, motile cytoplasts from polymorphonuclear leukocytes home to inflammatory lesions in vivo.

Cytokineplasts (CKP) are anucleate, motile, granule-poor fragments induced from polymorphonuclear leukocytes on surfaces by the brief application of heat. Derived from the peripheral cytoplasm and membranes of PMN, they retain the sensing, transducing, and effector mechanisms necessary for chemotaxis and phagocytosis, and appear to represent a functional, self-purification of the motile apparatus. Unlike their parent PMN, CKP are cryopreservable.

Recruitment of the cross-linked opsonic receptor CD32A (FcgammaRIIA) to high-density detergent-resistant membrane domains in human neutrophils.

We have previously shown that CD32A (or FcgammaRIIA), one of the main opsonin receptors, was rapidly insolubilized and degraded in intact neutrophils after its cross-linking. In view of these experimental difficulties, the early signalling steps in response to CD32A activation were studied in purified plasma membranes of neutrophils. After CD32A cross-linking in these fractions, the tyrosine phosphorylation of two major substrates, the receptor itself and the tyrosine kinase Syk, was observed.

Tick saliva reduces adherence and area of human neutrophils.

During natural infection with the agent of Lyme disease, Borrelia burgdorferi, spirochetes are delivered with vector saliva, which contains anti-inflammatory and antihemostatic activities. We show here that the saliva of ixodid ticks reduces polymorphonuclear leukocyte (PMN) adhesion via downregulation of beta2-integrins and decreases the efficiency of PMN in the uptake and killing of spirochetes. Inhibition of integrin adhesion and signaling reduces anti-inflammatory functions of PMN.

Calprotectin, an abundant cytosolic protein from human polymorphonuclear leukocytes, inhibits the growth of Borrelia burgdorferi.

We previously showed that numerous polymorphonuclear leukocyte (PMN) granule components efficiently kill Borrelia burgdorferi, the agent of Lyme disease. In addition, motile, granule-poor cytoplasts (U-Cyt) from human blood PMN can exert anti-Borrelia activity against opsonized B. burgdorferi independently of oxidative mechanisms.

Chemotaxis of non-compressed blood polymorphonuclear leukocytes from an adolescent with severe leukocyte adhesion deficiency.

We have defined the defect in a child with severe leukocyte adhesion deficiency-1 (LAD) as resulting from a single amino acid shift in CD18 (from a C to T mutation at position 533) that prevents heterodimerization with the CD11 antigens to produce beta(2) integrins-the first reported patient homozygous for this defect. Although beset by frequent infections, the patient has survived to adolescence despite the lack of these important adhesion molecules. Consistent with his clinical course is the ability of his PMN to respond chemotactically in slide preparations, albeit with difficulty because of their poor purchase on substrate.

Double-decker chemotaxis: no evidence for photonic stimulation of directed locomotion by human blood polymorphonuclear leukocytes.

The study was carried out under direct videomicroscopic control to ascertain whether electromagnetic forces (photons) can initiate directed cell motility of human polymorphonuclear neutrophils (PMN). Cell suspensions containing a mixture of randomly motile white blood cells and erythrocytes (red cells) were placed in a double-decked preparation created by a glass slide and two cover slips and sealed by paraffin. Erythrocytes in the upper or lower chamber were destroyed by a single burst from a narrow ruby laser beam.

Superoxide anion production during Anaplasma phagocytophila infection.

Anaplasma phagocytophila persists within neutrophils and prevents the respiratory burst by inhibiting gp91(phox). Mutations in gp91(phox) result in chronic granulomatous disease (CGD), which is diagnosed by use of the nitroblue tetrazolium (NBT) and Fc-Oxyburst assays that examine whether cells produce O2-. This study assessed whether the NBT and Fc-Oxyburst assays could detect a respiratory burst during A.

Chemotactic activity of human blood leukocytes in plasma treated with EDTA: chemoattraction of neutrophils about monocytes is mediated by the generation of NAP-2.

In slide preparations of human blood leukocytes in autologous plasma containing EDTA, many adherent monocytes are initially chemotactic for neutrophils (PMN). We have identified the chemotactic factor that they generate as neutrophil-activating peptide-2 (NAP-2), as evidenced by distraction of the gradient by authentic human NAP-2, the importance of platelets in the media, which elaborate the precursor of NAP-2, and suppression of the chemotactic response by serine protease inhibitors, which would block the monocyte-derived serine esterase that creates NAP-2 from its immediate precursor. Consistent with this conclusion is inhibition of the chemotactic response to monocytes by agents that block CXCR2, the receptor that NAP-2 uses.

Human phagocytic cells in the early innate immune response to Borrelia burgdorferi.

During natural infection with the agent of Lyme disease, Borrelia burgdorferi, polymorphonuclear leukocytes (PMNL) are the first cells of the innate immune system to arrive at the site of spirochete deposition in the skin. This study examined the degree of spirochete clearance likely to occur with PMNL or mononuclear cells before the development of the secondary immune response. Without specific antibody in vitro, there was very limited uptake of spirochetes by PMNL or monocytes and no intracellular colocalization of PMNL granule products with spirochetes.

Borrelia burgdorferi are susceptible to killing by a variety of human polymorphonuclear leukocyte components.

The killing of Borrelia burgdorferi by intact human polymorphonuclear leukocytes (PMNL) and by individual PMNL components was compared. Intact PMNL killed B. burgdorferi 6.

Misoprostol Stimulates cAMP Generation in Human Leukocytes: Synergy with Colchicine Suggests a New Potential for Established Drugs.

In isolated leukocytes, elevation of cAMP can inhibit various proinflammatory and immune functions. The prostaglandins E (PGEs) are known to stimulate leukocyte cAMP production, and for years they have been viewed as potential immunosuppressive and/or anti-inflammatory agents. However, their clinical use is severely limited by extreme metabolic instability and by poor oral absorption, which necessitates administration by infusion or injection.