Expression changes of nerve cell adhesion molecules L1 and semaphorin 3A after peripheral nerve injury

The expression of nerve cell adhesion molecule L1 in the neuronal growth cone of the central nervous system is strongly associated with the direction of growth of the axon, but its role in the regeneration of the peripheral nerve is still unknown. This study explored the problem in a femoral nerve section model in rats. L1 and semaphorin 3A m RNA and protein expressions were measured over the 4-week recovery period. Quantitative polymerase chain reaction showed that nerve cell adhesion molecule L1 expression was higher in the sensory nerves than in motor nerves at 2 weeks after injury, but vice versa for the expression of semaphorin 3A. Western blot assay results demonstrated that nerve cell adhesion molecule L1 expression was higher in motor nerves than in the sensory nerves at the proximal end after injury, but its expression was greater in the sensory nerves at 2 weeks. Semaphorin 3A expression was higher in the motor nerves than in the sensory nerves at 3 days and 1 week after injury. Nerve cell adhesion molecule L1 and semaphorin 3A expressions at the distal end were higher in the motor nerves than in the sensory nerves at 3 days, 1 and 2 weeks. Immunohistochemical staining results showed that nerve cell adhesion molecule L1 expression at the proximal end was greater in the sensory nerves than in the motor nerves; semaphorin 3A expression was higher in the motor nerves than in the sensory nerves at 2 weeks after injury. Taken together, these results indicated that nerve cell adhesion molecules L1 and semaphorin 3A exhibited different expression patterns at the proximal and distal ends of sensory and motor nerves, and play a coordinating role in neural chemotaxis regeneration.     

Universal architecture of bacterial chemoreceptor arrays

Chemoreceptors are key components of the high-performance signal transduction system that controls bacterial chemotaxis. Chemoreceptors are typically localized in a cluster at the cell pole, where interactions among the receptors in the cluster are thought to contribute to the high sensitivity, wide dynamic range, and precise adaptation of the signaling system. Previous structural and genomic studies have produced conflicting models, however, for the arrangement of the chemoreceptors in the clusters. Using whole-cell electron cryo-tomography, here we show that chemoreceptors of different classes and in many different species representing several major bacterial phyla are all arranged into a highly conserved, 12-nm hexagonal array consistent with the proposed “trimer of dimers” organization. The various observed lengths of the receptors confirm current models for the methylation, flexible bundle, signaling, and linker sub-domains in vivo. Our results suggest that the basic mechanism and function of receptor clustering is universal among bacterial species and was thus conserved during evolution.     

Neutrophil migration during liver cirrhosis in rabbits

1. The aim of the present study was to investigate neutrophil chemotaxis during the induction of liver cirrhosis in rabbits. 2. Liver cirrhosis was induced in male New Zealand white rabbits. The study consisted of three experimental groups: (i) group A (n=16) served as the control and received only normal chow and all rabbits in this group were killed at 16 weeks; (ii) group B rabbits (n=8) were killed immediately after the chemotaxis assay, which was performed 24 h after CCl4 administration, at weeks 2, 4, 6 and 8; and (iii) in group C rabbits (n=19), the chemotaxis assay was performed every second week on the day before CCl4 administration for 16 weeks and all animals in this group were killed at 16 weeks. 3. Four of six rabbits in group B had liver cirrhosis at week 8. In group C, liver cirrhosis occurred in seven of eight animals. All rabbits with liver cirrhosis had an inflammatory infiltrate of neutrophils. In group B, there was a significant increase in polymorphonuclear cells and neutrophil chemotaxis and a significant reduction in mononuclear leucocytes at week 8. The rabbits in group C showed a significant increase in total leucocyte and polymorphonuclear numbers at week 10. A significant increase in neutrophil chemotaxis was also observed from week 2 through to week 6. 4. The presence of neutrophils in the liver of all rabbits with cirrhosis, associated with an increase in polymorphonuclear cell chemotaxis during this process, supports the view that this cell type has an important role in the development of toxic liver damage.     

In vitro immunomodulatory activity of verbascoside from Nepeta ucrainica L

Nepeta ucrainica L. is used as a herbal tea in Kazakhistan. Phytochemical investigations of the aerial parts of the plant resulted in the isolation of verbascoside (1) and 1,5,9-epi-deoxyloganic acid (2). The structures of the compounds were elucidated by spectral (UV, IR, (1)H-NMR and (13)C-NMR) methods and HPLC analysis. The in vitro immunomodulatory activity of verbascoside was investigated by assessing neutrophil function; chemotaxis and intracellular killing activity. Verbascoside showed an increased chemotactic activity in all doses applied compared with the medium used as a negative control and had a positive effect on respiratory burst of neutrophils, but there was an opposite effect with increasing doses, pointing to a possible suppression of neutrophil intracellular killing activity.     

Inhibition of endothelial cell functions and of angiogenesis by the metastasis inhibitor NAMI-A

NAMI-A is a ruthenium-based compound with selective anti-metastasis activity in experimental models of solid tumours. We studied whether this activity was dependent on anti-angiogenic ability of NAMI-A. We thus investigated its in vitro effects on endothelial cell functions necessary for angiogenesis to develop, as well as its in vivo effects in the chick embryo chorioallantoic membrane model. Endothelial cell proliferation, chemotaxis, and secretion of the matrix-degrading enzyme metalloproteinase-2 were inhibited by NAMI-A in a dose-dependent manner, and without morphologic signs of cell apoptosis or necrosis. Lastly, NAMI-A displayed a dose-dependent in vivo anti-angiogenic activity in the chorioallantoic membrane model. These data suggest that the anti-angiogenic activity of NAMI-A can contribute to its anti-metastatic efficacy in mice bearing malignant solid tumours.     

Histamine-induced inhibition of neutrophil chemotaxis and T-lymphocyte proliferation in man

Histamine inhibits in vitro human neutrophil chemotaxis and T-lymphocyte proliferation via H2 receptors. The aim of this study was to verify these inhibitory effects of histamine in man in vivo. Healthy volunteers were challenged with histamine by intravenous (1 mg), subcutaneous (1 mg) and inhalatory (2.4 mg) routes. Venous blood was taken before and at different times after challenge. Neutrophil chemotaxis was studied by the Boyden assay and T-lymphocyte proliferation by counting H3-thymidine incorporation in cultured mononuclear cells. Plasma histamine was measured by radioimmunoassay. Histamine infusion caused transient systemic symptoms as well as a significant decrease of neutrophil chemotaxis (mean - 26% +/- 6) and of PHA-pulsed T-lymphocyte proliferation (mean - 16% +/- 6) 4 h after histamine challenge. Subcutaneous injection of histamine caused only a significant decrease of neutrophil chemotaxis (mean - 24% +/- 15) 4 h after injection. Histamine inhalation was well tolerated and caused a significant depression of neutrophil chemotaxis (mean - 40% +/- 15) and of T-lymphocyte proliferation (mean - 27% +/- 6) 2 and 4 h after the challenge. Histamine challenges were always accompanied by a rapid and transient rise in plasma histamine. Inhalation of an H2 agonist (impromidine) but not of an H1 agonist (betahistine) caused a decrease of neutrophil chemotaxis and of T-lymphocyte proliferation. Oral pretreatment with an H2 antagonist (cimetidine) before histamine inhalation prevented histamine-induced decrease of neutrophil chemotaxis and T-lymphocyte proliferation, whereas astemizole, an H1 antagonist, had no effect. In conclusion, during the few hours following administration, exogenous histamine in man causes a depression of neutrophil chemotaxis and T-lymphocyte proliferation via H2 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

ELEVATED LEVELS OF CHEMOTAXIS INHIBITORY ACTIVITY IN SERA OF PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS

An inhibitory activity against neutrophil chemotactic factors was found in normal human serum. Elevated levels of this chemotaxis inhibitory activity were demonstrated in sera of patients with systemic lupus erythematosus (SLE). The physico-chemical characteristics of this chemotaxis inhibitory substance(s) in SLE serum were almost identical to those of the inhibitory substance(s) in normal human serum; both the inhibitory substances were heat labile, soluble in 45% saturated ammonium sulphate, worked directly on chemotactic factor and affected various chemotactic factors. A study using Sephadex G- 100 chromatography showed that the molecular sizes of both inhibitory substances were almost identical. No correlation was found between the levels of the chemotaxis inhibitory activity in SLE sera and other clinical parameters including erythrocyte sedimentation rate, and serum concentration of either the third component of complement (C3) or the fourth component of complement (C4). Specimens from patients with the following diseases failed to demonstrate elevated levels of chemotaxis inhibitory activities; rheumatoid arthritis, urticaria, psoriasis vulgaris, atopic dermatitis and discoid lupus erythematosus (DLE).     

Alteration of Human Leukocyte Chernotaxis, Chemiluminescence, and HMP Shunt Activity Caused By Mechanical Trauma

The effect of graded shear stress exposure (0 to 800 dynes/cm² at 35°C) on human leukocyte function was examined in vitro, using a concentric cylinder viscometer. Boyden Chamber chemotaxis was significantly reduced at stress levels above 150 dynes/cm², and was over a factor of three lower after exposure to trauma levels of 450 dynes/cm² Hexose monophosphate (HMP) shunt activity following particle ingestion was also significantly lower after exposure to shear stresses of 150 dynes/cm² or more for ten minutes. PMN chemiluminescence was reduced following stress trauma of 450 dynes/cm² using whole blood, and after 150 dynes/cm² using leukocyte suspensions. All the functional alterations reported appear to be bulk shear stress effects and not due to surface interaction, as changing the surface-to-volume ratio in the viscometer by over a factor of three did not change the damage caused at a given stress level. These functional alterations caused by mechanical trauma may be important in hemodialysis, cardiopulmonary bypass, venovenous perfu-sion, and in any blood-contacting artificial organ. The stress levels required for damage are of the same order as those required for platelet functional alteration, and much lower than those required for erythrocyte hemolysis for the same exposure times.     

Defective chemotaxis and adherence in granulocytes from chronic myeloid leukemia (CML) patients

Adherence and motility of granulocytes from chronic myeloid leukemia (CML) patients was compared with that of granulocytes from normal subjects. The percentage of non-adherent granulocytes was significantly higher in untreated CML patients and patients in relapse and acute blastic crisis (ABC) (P less than 0.01). Chemotactic Index (C.I.) of granulocytes moving in a gradient of a synthetic chemoattractant F-Met-Leu-Phe was measured by time-lapse cinématography. While 84.5 +/- 3.53% of normal granulocytes were motile, only 30.3 +/- 14.7% granulocytes from untreated patients, 33.8 +/- 21.3% granulocytes from relapse patients and 36 +/- 9.9% granulocytes from ABC patients were found to be motile. The C.I. of motile granulocytes from CML patients was significantly lower in untreated patients (P less than 0.05), in patients in relapse (P less than 0.01) and in patients in ABC (P less than 0.05), as compared to that of normal granulocytes. Visualization of cytoplasmic actin by indirect immunofluorescence, revealed the presence of actin in granulocytes from patients in all stages of the disease. Thus, granulocytes from CML patients were defective in directional locomotion. Organized actin filaments were found in the small percentage of motile cells still found in CML patients.     

Dentin Sialoprotein and Phosphoprotein Induce Neutrophil Recruitment: A Mechanism Dependent on IL-1β, TNF-α, and CXC Chemokines

Dentin is a reservoir of several potentially active molecules, and dentin sialoprotein (DSP) and dentin phosphoprotein (DPP) are the two major noncollagenous proteins. It has been established that dentin molecules are released as a consequence of osteoclast action during the resorption process. Along with osteoclasts, inflammatory cells seem to play an important role at sites of root resorption. Although the role of dentin molecules in dentinogenesis is well known, their role in pathological processes associated with dentin matrix dissolution is unclear. Recent studies have suggested that dentin components may function as chemotactic and activator signals for inflammatory cells at these sites. Herein we present evidence that demineralized dentin crude extract, DSP, and DPP induced dose- and time-dependent neutrophil migration into the peritoneal cavity of mice and that this activity was inhibited by dexamethasone, but not by indomethacin or MK886. The blockade of tumor necrosis factor- (TNF-) and interleukin-1 (IL-1) receptors inhibited neutrophil accumulation. The neutrophil migration was also diminished in the absence of the chemokines cytokine-induced neutrophil chemoattractant (KC) and macrophage inflammatory protein-2 (MIP-2), but not in the absence of macrophage inflammatory protein-1 (MIP-1). These results demonstrate that dentin induces neutrophil migration via the synthesis of IL-1, TNF-, and chemokines and they suggest that dentin matrix proteins may have an active role in inflammatory cell recruitment during pathological processes associated with dentin and bone matrix dissolution.