DEFECTIVE NEUTROPHIL CHEMOTAXIS AND HYPERIMMUNOGLOBULINEMIA E—A REVERSIBLE DEFECT?

Abstract. An eleven-month-old boy is presented with chronic atopic dermatitis and recurrent infections of the skin and respiratory tract, including subcutaneous abscesses. Immunological studies disclosed a neutrophil chemotactic defect, blood eosinophilia and serum hyper IgE. The clinical and analytical data are similar to those of patients previously described by Hill & Quie. A diet free of the allergens which were responsible for the atopic dermatitis reversed the chemotactic defect, the blood eosinophilia and the clinical symptoms.     

Developmental alterations in sensory neuroanatomy of the Caenorhabditis elegans dauer larva

The anterior sensory ultrastructure of the C. elegans dauer larva was examined in several specimens and compared with that of the second-stage (L2) larva, which immediately precedes the dauer stage. In some instances comparisons were made with L3, postdauer L4, and adult stages. Whereas sensory structures in different nondauer stages closely resemble each other, including the inner labial sensilla, amphids, and deirids. The relative positions of the afferent tips of the two types of inner labial neurons are reversed in the dauer stage compared to the L2 and postdauer L4 stages. Inner labial neuron 1 rather than neuron 2 is more anterior in each of the six sensilla, and neuron 1 has an enlarged tip. The neuron 2 cilia are only one-third as long as those in the L2. Amphidial neurons c, d, g, and i and the amphidial sheath cell are altered in shape or position in the dauer stage. Neurons g and i are displaced posteriorly within the dauer amphidial channel. Neuron d has significantly more microvillar projections than do the d cells in L2, L3, or postdauer L4 larvae. Winglike processes of dauer neuron c form a 200 degrees-240 degrees arc in transverse section, including extensive overlap of the two cells. The arc in an L2 seldom spans more than 100 degrees, and overlap does not occur. While L2 larvae possess two separate bilateral amphidial sheath cells, the left and right sheath cells are often continuous in the dauer larva. Deirid sensory dendrites exhibit a dauer-specific structure and orientation. The tip of each neuron is attached to the body wall cuticle by a substructure not observed in L2 or postdauer L4 stages, and the neurons are oriented parallel to the longitudinal axis of the dauer larva. The deirid sensory terminals are oriented perpendicular to the cuticle in other stages. Reversible alterations in neural structure are discussed in the context of dauer-specific behavior.     

EXPLORING COW'S MILK AND SOY PROTEIN SENSITIVITY IN HUMAN INFANTS

Depressed neutrophil chemotaxis and enhanced random migration were found in 11 infants with active cow's milk or soy protein intolerance. The depressed chemotaxis returned to normal in four recovered infants.     

Switching direction in electric-signal-induced cell migration by cyclic guanosine monophosphate and phosphatidylinositol signaling

Switching between attractive and repulsive migration in cell movement in response to extracellular guidance cues has been found in various cell types and is an important cellular function for translocation during cellular and developmental processes. Here we show that the preferential direction of migration during electrotaxis in Dictyostelium cells can be reversed by genetically modulating both guanylyl cyclases (GCases) and the cyclic guanosine monophosphate (cGMP)-binding protein C (GbpC) in combination with the inhibition of phosphatidylinositol-3-OH kinases (PI3Ks). The PI3K-dependent pathway is involved in cathode-directed migration under a direct-current electric field. The catalytic domains of soluble GCase (sGC) and GbpC also mediate cathode-directed signaling via cGMP, whereas the N-terminal domain of sGC mediates anode-directed signaling in conjunction with both the inhibition of PI3Ks and cGMP production. These observations provide an identification of the genes required for directional switching in electrotaxis and suggest that a parallel processing of electric signals, in which multiple-signaling pathways act to bias cell movement toward the cathode or anode, is used to determine the direction of migration.     

WIP and WASP play complementary roles in T cell homing and chemotaxis to SDF-1alpha

Homing of lymphocytes to tissues is a biologically important multistep process that involves selectin-dependent rolling, integrin-dependent adhesion and chemokine-directed chemotaxis. The actin cytoskeleton plays a central role in lymphocyte adhesion and motility. Wiskott-Aldrich syndrome protein (WASP), the product of the gene mutated in Wiskott-Aldrich syndrome, and its partner, the Wiskott-Aldrich syndrome protein-interacting protein (WIP), play important roles in actin re-organization in T lymphocytes. We used mice with disruption of the WASP and WIP genes to examine the role of WASP and WIP in T cell homing. T cell homing to spleen and lymph nodes in vivo was deficient in WASP-/- and WIP-/- mice and severely impaired in WASP-/-WIP-/- double knockout (DKO) mice. Deficiency of WASP, WIP or both did not interfere with selectin-dependent rolling or integrin-dependent adhesion of T cells in vitro. Chemotaxis to stromal cell-derived factor-1alpha (SDF-1alpha) in vitro was mildly reduced in T cells from WASP-/- mice. In contrast, it was significantly impaired in T cells from WIP-/- mice and severely reduced in T cells from DKO mice. Cellular F-actin increase following SDF-1alpha stimulation was normal in WASP-/- and WIP-/- T cells, but severely reduced in T cells from DKO mice. Actin re-organization and polarization in response to SDF-1alpha was abnormal in T cells from all knockout mice. Early biochemical events following SDF-1alpha stimulation that are important for chemotaxis and that included phosphorylation of Lck, cofilin, PAK1 and extracellular regulated kinase (Erk) and GTP loading of Rac-1 were examined in T cells from DKO mice and found to be normal. These results suggest that WASP and WIP are not essential for T lymphocyte rolling and adhesion, but play important and partially redundant roles in T cell chemotaxis in vitro and homing in vivo and function downstream of small GTPases.     

Expression profiles of matrix metalloproteinase 9 in teleost fish provide evidence for its active role in initiation and resolution of inflammation

Matrix metalloproteinase 9 (MMP-9) belongs to a family of zinc-dependent endopeptidases. As a consequence of its ability to cleave structural extracellular matrix molecules, mammalian MMP-9 is associated with vital inflammatory processes such as leucocyte migration and tissue remodelling and regeneration. Interestingly, MMP-9 genes have been identified in fish, but functional data are still limited and focus on the involvement of MMP-9 in embryonic development, reproduction and post-mortem tenderization. Here, we describe the involvement of MMP-9 in the innate immunity of carp. In carp, MMP-9 was most notably expressed in classical fish immune organs and in peritoneal and peripheral blood leucocytes, indicating a role of MMP-9 in immune responses. In our well-characterized zymosan-induced peritonitis model for carp, we analysed expression of the MMP-9 gene and the gelatinolytic levels of both pro- and activated forms of MMP-9. The biphasic profile of MMP-9 mRNA expression indicated involvement during the initial phase of inflammation and during the later phase of tissue remodelling. Also, in vitro stimulation of carp phagocytes with lipopolysaccharide or concanavalin A increased MMP-9 gene expression, with a peak at 24 hr. The increase of MMP-9 mRNA correlated with the peak of MMP-9 gelatinolytic level in culture supernatants. These results provide evidence for an evolutionarily conserved and relevant role of MMP-9 in the innate immune response.     

α-Synuclein,a chemoattractant,directs microglial migration via H2O2-dependent Lyn phosphorylation

Malformed α-Synuclein (α-syn) aggregates in neurons are released into the extracellular space, activating microglia to induce chronic neuroinflammation that further enhances neuronal damage in α-synucleinopathies, such as Parkinson’s disease. The mechanisms by which α-syn aggregates activate and recruit microglia remain unclear, however. Here we show that α-syn aggregates act as chemoattractants to direct microglia toward damaged neurons. In addition, we describe a mechanism underlying this directional migration of microglia. Specifically, chemotaxis occurs when α-syn binds to integrin CD11b, leading to H₂O₂ production by NADPH oxidase. H₂O₂ directly attracts microglia via a process in which extracellularly generated H₂O₂ diffuses into the cytoplasm and tyrosine protein kinase Lyn, phosphorylates the F-actin–associated protein cortactin after sensing changes in the microglial intracellular concentration of H₂O₂. Finally, phosphorylated cortactin mediates actin cytoskeleton rearrangement and facilitates directional cell migration. These findings have significant implications, given that α-syn–mediated microglial migration reaches beyond Parkinson’s disease.Although progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) is a pathological hallmark of Parkinson’s disease (PD), the disorder also features activated microglia-mediated chronic inflammation and the accumulation of α-Synuclein (α-syn) in affected regions of the SNpc, suggesting that both activated microglia and α-syn contribute to the pathogenesis of PD.α-Synuclein, a soluble protein that performs multiple physiological functions (1, 2), aggregates under challenging genetic or environmental conditions (3, 4). Accumulations of α-syn in neurons are toxic (5), most likely via impairment of ubiquitin-proteasomal and autophagy-lysosomal pathways, increased chronic endoplasmic reticulum stress, and mitochondrial dysfunction, among other mechanisms (6–9). In vitro and in vivo studies also have demonstrated that α-syn species, predominantly oligomers, can be released from neurons into the extracellular space (10, 11), stimulating microglial activation (10, 12) and initiating neuroinflammation. If unregulated, microglial activation may induce the release of inflammatory mediators, such as TNF-α, monocyte chemotactic protein-1 (MCP-1), and reactive oxygen species (ROS), to sites of neuroinflammation, causing progressive neuronal damage (13, 14).Currently little is known about the mechanism by which α-syn affects microglial activity, especially motility. Several studies have reported that the extent of microglial activation in the SNpc correlates with α-syn accumulation. This result, together with the finding that microglia preferentially colocalize with aggregated α-syn in the SNpc (15, 16), led us to hypothesize that α-syn aggregates may act as chemoattractants to direct microglial migration toward neurons releasing α-syn into the interstitial tissue.Here we show that the binding of α-syn to CD11b on microglia is sufficient and necessary for microglial directional migration. Furthermore, H₂O₂ originating from activated NADPH oxidase (Nox2), a key enzyme in microglia, serves as a direct signal that drives microglial migration. Finally, we identify a unique molecular event as critical to microglial directional migration: Lyn, a Src family kinase (SFK), senses changes in the intracellular concentration of H₂O₂ in microglia and phosphorylates the F-actin–associated protein cortactin, resulting in actin filament rearrangement and microglial directional migration.     

Release of neutrophil chemotactic factors from gastric tissue

This study was designed to characterize neutrophil chemotactic factors released by gastric tissue. Full-thickness rabbit stomach (organ culture) was prepared and incubated in Ringer's solution at 37°C. Culture supernatants were collected at 1, 2, 3, and 4 hr and assayed for neutrophil chemotactic activity in modified Boyden chambers. High levels of chemotactic activity were seen at 3 hr of incubation. Antral and fundic tissue were equally capable of producing neutrophil chemotactic activity. In addition, high levels of activity were seen from both the serosal and mucosal surfaces. Initial biochemical characterization of these gastricderived factors revealed that: (1) a majority of the activity (80–90%) exhibited molecular weight values of greater than 300 kDa, (2) the chemotactic activity was heat stable but was partially reduced by treatment with a protease, subtilisin (37% inhibition), and (3) 70–80% of the activity in the supernatants was extracted into organic solvent (ethyl acetate). These factors may prove to be important in recruitment of neutrophils to areas of gastric injury.Support by a Department of Surgery Research Grant.Presented in part at the annual meeting of the American Gastroenterological Association, May, 1988, New Orleans.     

Chemotactic response of vascular smooth muscle cells to acetoacetylated low-density lipoprotein

Summary We studied the effect of acetoacetylated low-density lipoprotein (LDL), which is recognized by the scavenger receptor, on the migration of fetal bovine aortic smooth muscle cells in culture, using a Neuro Probe 48-well microchemotaxis chamber. Acetoacetylated LDL is chemotactic and chemokinetic for the smooth muscle cells, and the effect is maximal with 50µg/ml of protein, while native LDL has no significant chemotactic activity. These results suggest that denatured LDL might play an important role in the recruitment of smooth muscle cells from the media into the intima in atherosclerosis.