Modulation of human neutrophil functions in vitro by Treponema denticola major outer sheath protein

In this study of human polymorphonuclear leukocytes (PMNs), pretreatment with Treponema denticola major outer sheath protein (Msp) inhibited formyl-methionyl-leucyl-phenylalanine (fMLP)-induced chemotaxis, phagocytosis of immunoglobulin G-coated microspheres, fMLP-stimulated calcium transients, and actin assembly. Msp neither altered oxidative responses to phorbol myristate or fMLP nor induced apoptosis. Msp selectively impairs chemotaxis and phagocytosis by impacting the PMN cytoskeleton.     

Modulation of human macrophage functions by gangliosides

In human tumors of neuroectodermal origin cell surface expression of individual gangliosides is either increased or decreased relative to comparable normal cells. We have previously shown that gangliosides shed from melanoma cells can immunomodulate T cell activity. Monocytes/macrophages (m/m) are known to play an important role as accessory and effector cells in immune responses. We therefore investigated the effect of exogenous gangliosides derived from melanoma on m/m functions in vitro. Gangliosides commonly expressed on human melanoma such as GM3, GD3, GM2, and GD2 were investigated, as well as GM1, a major component of human neural tissue. Monocytes were isolated from human peripheral blood mononuclear cell populations, treated with gangliosides in vitro, and evaluated in several functional assays. Treatment of m/m with GM2 and GM3 gave the greatest inhibition of Fc receptor expression. GM1 and GD3 on the other hand most inhibited the production of interleukin-1 (IL-1) by m/m. Production of tumor necrosis factor (TNF) like monocytoxin was not affected by incubation with individual gangliosides. These studies suggest that individual melanoma gangliosides have different regulatory effects on m/m functions.     

Modulation of angiogenic functions in human macrophages by biomaterials

We examined the ability of polyvinylchloride (PVC), polytetrafluorethylene (PTFE) and tissue culture polystyrene (TCPS) to affect angiogenic functions in human monocyte-derived macrophages by measuring the mRNA expression of genes encoding angiogenic and anti-angiogenic molecules including basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1) and thrombospondin-1 (Tsp-1). The angiogenic activity of the corresponding macrophage conditioned media (CM) was measured by the proliferation of endothelial cells and the sprouting of new capillaries from fragments of human placental blood vessels. We determined that bFGF was not expressed in macrophages while VEGF and Tsp-1 mRNAs were expressed constitutively. Ang-1 was expressed in macrophages cultured up to 7 days on PTFE and TCPS independent of the culture stage. In contrast, macrophages cultured on PVC did not produce detectable amounts of Ang-1 mRNA after 7 days. CM from macrophages cultured either on PTFE or TCPS stimulated angiogenesis whereas CM from macrophages cultured on PVC inhibited it. The results demonstrate that polymers can cause differential expression of the angiogenic molecule Ang-1 in macrophages. They also induce different phenotypes of macrophages, which can either stimulate or inhibit angiogenesis suggesting a material-dependent influence on neovascularization.     

The effect of polyethylene particle chemistry on human monocyte-macrophage function in vitro

Osteolysis remains the most important problem in orthopedic implant failure. Wear debris from the implant contains polyethylene (PE) particulate which has been shown to activate monocyte-derived macrophages (MDM). Although the response of MDM has been shown to be influenced by the size, shape, and chemical type of PE, the effect of chemically altered PE on MDM has not been studied. In this study, human MDM were seeded onto glass coverslips coated with virgin high density (HD)PE and chemically modified HDPE (impregnated with ppm levels of CoCl(2) and oxidized by heat) mixed with type I collagen and cultured for 96 h. Light microscopic evaluation demonstrated consistent phagocytosis of the HDPE particulate that was confirmed by scanning electron and transmission electron microscopy with little evidence of cytotoxicity. Evaluation of pro-inflammatory mediator secretion by MDMs in response to the virgin and chemically modified HDPE revealed significant differences in interleukin (IL)-1, tumor necrosis factor (TNF)-alpha, and IL-6 secretion. A significant elevation of IL-1 secretion was observed after initial exposure to virgin HDPE particles compared with controls (p = 0.001). IL-1 secretion was also elevated in the low oxidized particle groups (p = 0.001), whereas the highly oxidized particles were not different than controls. Secretion of both IL-6 (p = 0.03) and TNF-alpha (p = 0.007) were significantly elevated by the low oxidized HDPE particles whereas the virgin and highly oxidized groups showed no difference. The different effects on MDM activation when HDPE surface chemistry was altered, highlight the importance of defining the particle properties when studying the role of MDM activation in in vitro systems and extrapolating these observations to the in vivo situation.     

Modulation of human lymphocyte functions by group A streptococci

Intact (heat-inactivated) bacteria and isolated cellular components of pathogenic group A (M type 5 or 12). B. C. and G streptococci were used to evaluate the in vitro reactivity of mononuclear cells (MNC) from peripheral blood of healthy donors and from human tonsils. High doses of A-streptococcal cells, cell walls, and cell membranes stimulated DNA synthesis, production of leukocyte migration inhibitory factor (LIF), and immunoglobulin (Ig) secretion in MNC from all donors. A streptrococci stimulated higher proliferation rates and larger numbers of plaque-forming cells (PFC) in tonsil cell cultures than in blood MNC cultures. Polyclonal activation of both tonsil and blood B lymphocytes by A-streptococcal cell components was T cell and monocyte dependent, thus showing a similarity between these structures and pokeweed mitogen (PWM), which is a polyclonal T-cell activator (PTA). Cocultivation studies demonstrated that, in the presence of A streptococci, precultured MNC and T cells can suppress the blastogenic and PFC responses of autologous fresh MNC stimulated by phytomitogen or antigen, which is very similar to the concanavalin A (Con A)-induced activation of suppressor cells. In contrast, similar group B-, C-, and G-streptococcal cell envelope biostructures failed to activate blood or tonsil lymphocytes to proliferate, differentiate, or produce LIF.     

Stress-related neuroimmunomodulation of monocyte-macrophage functions in HIV-1 infection

Monocytes/macrophages play a central role in the afferent and efferent limbs of the immune system. Macrophages perform several immunological functions both in vivo and in vitro, including antigen presentation, tumor cell killing, phagocytosis, and bacterial and viral killing. Acquired immunodeficiency syndrome (AIDS), a disease characterized by a profound immunodeficiency, induces a wide range of neuropsychological abnormalities. The occurrence of severe psychological disturbances, including stress, depression, and anxiety increase psychological and physical indices of morbidity among patients. Stress influences several immunological responses in man and animals and is usually accompanied by altered blood levels of various CNS-related peptides or neurohormones. Monocytes/macrophages express surface receptors for different CNS-secreted molecules. In ARC and AIDS patients abnormal neuropeptide levels may be related to severe psychological disturbances. Neuropeptides and neurohormones may play a central role in stressed HIV-1-infected patients by affecting monocyte-macrophage functions, which may further trigger disease progression and immunologic deficiency. It is hypothesized that stress reactions lead to altered release of neurohormones and/or neuropeptides which affect monocyte-macrophage functions and favor progression of HIV-1-related disease.     

Selenium and the immune response: 1. Modulation of alloreactive human lymphocyte functions in vitro

A role for the dietary trace mineral element selenium in the reduction of cancer incidence has been documented in numerous epidemiological and experimental studies. The precise mechanism of this antitumor effect is not well understood, but published data suggest that both inhibition of tumor cell growth and enhancement of host immunity are likely to be involved. In this study we report that selenium at physiologic concentrations can inhibit human lymphocyte proliferation in response to irradiated tumor cells in mixed lymphocyte/tumor cell cultures (MLTC). In addition, we demonstrate that the various lymphocyte functional activities generated in these cultures exhibit different levels of sensitivity to the effects of selenium. The generation of suppressor-cell activity in MLTC was strongly inhibited by the presence of physiologic levels of selenium, while the development of cytotoxic T-lymphocyte activity in identical cultures was not affected by selenium. Production of interleukin-2 in these cultures showed an intermediate sensitivity to the effects of selenium. Thus, selenium appears to be capable of selectively regulating the generation of functional lymphocyte subsets in vitro. Such selective regulation could explain the published effects of selenium on immunity and would be consistent with a role for immunity in the observed reduction of cancer incidence associated with elevated selenium intake.     

Possible role of histidine decarboxylase (HDC) and histamine in human in vitro monocyte-macrophage differentiation

Inflammation Research -     

Modulation of morphology and functions of human hepatoblastoma cells by nano-grooved substrata

It is known that cellular behavior is affected by nano-patterned topography. For example, many cell types tend to align and extend along the direction of nano-grooves/ridges structures. In this study, we investigated the impact of nano-grooves/ridges on hepatocyte morphology and functions. HepG2/C3A (C3A) cells were cultured on nano-grooved silicon or polystyrene substrata with various widths (from 100 to 500 nm) and depths (from 100 to 380 nm). Nano-grooved substrates induced dramatic changes in C3A cell morphology. The cells formed spheroids on the flat substrates, while C3A cells spread and grew confluently with elongated and aligned morphology along the nano-grooves/ridges. Albumin synthesis was enhanced on the nano-grooved silicon substrates compared to the flat surface, and was decreased with increasing groove depths. Urea conversion on the shallow grooves (400 nm wide and 100 nm deep) remained at the same level of that on the flat surfaces, but was decreased on the deeper grooves. We found that the functions of hepatocytes were enhanced on the substrates with shallow grooves. The nano-grooved substrates may be applied as in vitro culture systems of hepatocytes for both diagnostic and therapeutic applications.     

Modulation of the constitutive or cytokine-induced bronchial epithelial cell functions in vitro by fluticasone propionate

When exposed to proinflammatory mediators, human bronchial epithelial cells (HBECs) upregulate the 'constitutive' adhesion molecule expression and cytokine/chemokine release. We tested whether and to what extent the inhibitory effect of fluticasone propionate on HBECs could involve the 'constitutive' and 'cytokine-induced' proinflammatory functions. Stimulation of the HBECs with interleukin (IL)-4 plus tumour necrosis factor (TNF)-alpha was more effective in upregulating intercellular adhesion molecule (ICAM)-1 ( approximately 2.2-fold increase) than vascular adhesion molecule (VCAM)-1 ( approximately 1.6-fold increase) expression (P<0.05) and in increasing the release of 'regulated on activation normal T cell expressed' (RANTES, 5.7-fold increase) than of IL-8 (3.5-fold increase) and granulocyte macrophage-colony stimulating factor (GM-CSF, 2.8-fold increase), (P<0.01). Fluticasone propionate, at the two concentrations tested (10 and 100 nM), was more effective in inhibiting the 'IL-4 plus TNF-alpha-induced' ICAM-1 expression than VCAM-1 expression (P<0.05) and in downregulating RANTES than IL-8 or GM-CSF secretion (P<0.05). The degree of inhibition demonstrated by fluticasone propionate appeared to be related to the degree of cell activation. In addition, for both adhesion molecules, the effect of fluticasone propionate at both concentrations tested appeared to be related to a complete inhibition of 'IL-4 plus TNF-alpha-induced' expression with no involvement of the 'constitutive' expression. Slightly different results were observed for cytokine/chemokine release. Indeed, evaluating RANTES, a complete inhibition of the 'IL-4 plus TNF-alpha-induced' release with a partial inhibition also of the 'constitutive' release at both concentrations of the drug tested was found, whereas for GM-CSF and IL-8, only a partial inhibition of the 'IL-4 plus TNF-alpha-induced' release in the presence of fluticasone propionate 10 and 100 nM. Thus, HBECs can constitutively or upon activation express adhesion molecules and secrete proinflammatory proteins at various levels and the different ability of fluticasone propionate to modulate the HBEC functions appears to be mostly related to the different inhibition of the various 'IL-4 plus TNF-alpha-induced' responses.     

Modifications of sialidase activity during the monocyte-macrophage differentiation in vitro

Human mononuclear cells were isolated from peripheral blood by centrifugation over Ficoll Hypaque, followed by adherence to plastic dishes. Monocyte-derived macrophages were obtained after culture for 3 or 5 days of the adherent cells in RPMI medium containing 20% heat-inactivated foetal calf serum. The sialidase activities were assayed in the whole homogenate using sodium 4-methyl-umbelliferyl-alpha-D-neuraminate as substrate, at various pHs, ranging from 3.6 to 6. The in vitro differentiation of monocytes into macrophages from day 0 up to day 5 was accompanied by a significant (P less than or equal to 0.01) increase in the sialidase activity on both a per-cell (+360%) and a per-mg protein in the homogenate (+125%) basis.     

Quantitative assays of human monocyte-macrophage function.

Monocyte-macrophages are required for the development of cell mediated immunity to a variety of microorganisms and tumors. Quantitative assays of human monocyte-macrophage function would be most useful in the evaluation of cell mediated immune function in man. Five quantitative assays are described that provide a human monocyte-macrophage function profile. These assays parallel the physiologic steps necessary for monocyte-macrophages to function as phagocytes: 1) chemotaxis, 2) opsonization, 3) phagocytosis, 4) phagocytosis-induced metabolic stimulation and 5) destruction of foreign material. Application of these quantitative assays will allow detection and dissection of disorders of monocyte-macrophage function in man.     

Modulation of immune response in vitro and in vivo by human granulocyte factors

The adherence of granulocytes induces secretion of specific granule contents. The secreted proteins were termed granulocyte factors (GF). The experiments in vivo provide evidence that GF play an essential role in the stimulation of PFC in BALB/c mice immunized with SRBC when applied before challenge three times (5 micrograms per mouse), but 50 micrograms per mouse given in the same way diminishes the response. To elucidate this discrepancy, the effect of GF on the generation of suppressor cells (SC) and helper cells (HC) in vitro has been investigated. Antigen specific nonadherent SC or HC were induced in vitro using CBA mice spleen cells incubated with 100 micrograms/ml or 0.1 mg/ml of TNP-KLH, respectively, for 4 days. GF in concentrations of 0.1 to 1 microgram/ml abolish antigen specific SC generation. SC and HC activity was tested in cooperative cultures. Antigen specific SC in delayed hypersensitivity (DTH) to BCG were induced in an in vitro system as above using normal BALB/c spleen cells and 100 micrograms/ml PPD. Nonadherent suppressor cells were transferred intravenously into cyclophosphamide (CY)-treated syngeneic recipients. The recipients were immunized to BCG immediately after the cell transfer. DTH was measured by foot-pad reaction. This reaction was positive to PPD in CY treated mice immunized to BCG, while it was suppressed by the transfer of in vitro induced SC. When the SC were induced in the presence of 1 microgram/ml GF, the suppression was abrogated. The higher GF concentrations stimulated SC activities when they were measured in response to a nonrelated antigen and in specific anti-PPD response, but the HC inhibition could not be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)     

Modulation of polymorphonuclear neutrophil functions by astrocytes

Background  

Neuroinflammation is a complex process involving cells from the immune system and the central nerve system (CNS). Polymorphonuclear neutrophils (PMN) are the most abundant class of white blood cells, and typically the first type of leukocyte recruited to sites of inflammation. In the CNS, astrocytes are the most abundant glial cell population and participate in the local innate immune response triggered by a variety of insults. In the present study, we investigated the impacts of astrocytes on PMN function.     

Modulation of immune functions by measles virus

Measles virus remains among the most potent global pathogens killing more than 1 million children annually. A profound suppression of general immune functions occurs during and for weeks after the acute disease, which favors secondary infections. In contrast, virus-specific immune responses are efficiently generated, mediate viral control and clearance and confer a long-lasting immunity. Because they sense pathogen-associated molecular patterns, and subsequently initiate and shape adaptive immune responses, professional antigen-presenting cells (APC) such as dendritic cells are likely to play a key role in the induction and quality of the virus-specific immune response. Key features of immune suppression associated with measles virus, however, are compatible with interference with APC maturation and function and subsequent qualitative and quantitative alterations of T cell activation. Acknowledgments. The authors thank Ingo Klagge for preparing the illustrations and the Deutsche Forschungsgemeinschaft, the Bundesministerium für Bildung und Forschung, the World Health Organization and the Humboldt Foundation for financial support of their laboratory work. Correspondence to: S. Schneider-Schaulies     

Modulation of glial cell functions by adenosine receptors

Adenosine is an endogenous neuromodulator, acting on four distinctive G-protein-coupled receptors, the A1, A2A, A2B and A3 adenosine receptors. Increased neuronal activity and, hypoxia or ischemia, result in elevated levels of adenosine reflecting changes of the metabolic state. This increases activation of the adenosine receptors. It is well appreciated that adenosine has a neuroprotective role in brain injuries. Although adenosine effects have been explained mainly by actions on nerve cells, modulation of glial functions by adenosine is likely to be important as discussed in this minireview. Thus, in astrocytes adenosine receptors modulate inter alia glycogen metabolism, glutamate transporters, astrogliosis and astrocyte swelling. Microglial cells appear to be important in regulating adenosine formation from ATP and adenosine can affect many microglial signaling pathways. Adenosine receptors on oligodendrocytes regulate white matter development.     

Modulation of cell functions of human tendon fibroblasts by different repetitive cyclic mechanical stress patterns

Mechanical stress is a factor that is thought to play an essential role in tissue generation and reparation processes. The aim of the present study was to investigate the influence of different repetitive cyclic longitudinal stress patterns on proliferation, apoptosis and expression of heat shock protein (HSP) 72. To perform this study, human tendon fibroblasts were seeded on flexible silicone dishes. After adherence to the dish, cells were longitudinally stressed with three different repetitive stress patterns having a frequency of 1 Hz and an amplitude of 5%. The proliferation and apoptosis rates were investigated 0, 6, 12 and 24 hours after application of cyclic mechanical longitudinal strain. Expression of HSP 72 was tested after 0, 2, 4 and 8 hours. Control cells were also grown on silicone dishes, but did not receive any stress. Stress patterns applied during one day resulted in a significant increase in proliferation and a slight increase in apoptosis. HSP 72 expression was rather unchanged. A stress pattern applied during two days resulted in a reduced proliferation and apoptosis rate whereas the expression of HSP 72 showed a significant increase. This study shows that different stress patterns result in different cellular reactions dependent on the strength of applied stress. Repetitive stress applied during one day stimulated proliferation and apoptosis in contrast to an extended stress duration. The latter induced an inhibition of proliferation and apoptosis probably through an increased HSP 72 activity. This may be related to an excess of applied stress. Our results may implicate future modulation techniques for tissue reparation and tissue engineering.     

Inhibition of human monocyte-macrophage and lymphocyte cytotoxicity to herpes simplex-infected cells by glucan.

The effect of short term in vitro incubation of glucan--a reticuloendothelial system stimulator--on subsequent cytotoxicity of human monocyte-macrophages (MP) and lymphocytes (L) to Herpes simplex virus-infected cells in a 51Cr-release assay was analyzed. Particulate, cell-associated glucan irreversibly inhibited MP antibody-dependent cellular cytotoxicity (ADCC). In contrast, the inhibition of L-ADCC and L-natural killer cytotoxicity could be reversed by dissociation of glucan and cells utilizing serum gradient centrifugation, a process which did not remove the glucan. These experiments reveal further basic differences between MP and L-ADCC using the reagent glucan.