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Biomedical subjects

S S Lefkowitz

Publications and source records attributed to S S Lefkowitz.

At least 37 records · Page 2Linked to original sources
PubMed1995

Neutrophil-macrophage interaction: a paradigm for chronic inflammation.

Autoimmune diseases, such as rheumatoid arthritis and inflammatory bowel disease are characterized by chronic inflammatory responses resulting in tissue damage. These diseases have a number of common denominators including: abnormal cytokine expression, aberrant antigen-antibody complexes, T cell anomalies, and increased numbers of neutrophils and macrophages. We propose that the interaction between neutrophils and macrophages induces a state of chronic inflammation which contributes to the disease state. One of the central players in this scenario is myeloperoxidase (MyPo). This enzyme functions in the 'cytotoxic triad' and is involved in cell killing. Studies done by the present investigators have known that MyPo, which is released from neutrophils, induces macrophages to secrete interleukin-1, interferon alpha beta and tumor necrosis factor alpha. Furthermore, our studies have suggested a major immunoregulatory role of this enzyme. We propose that the release of MyPo from neutrophils and subsequent binding to macrophages initiates a cascade of events which enhance the production of reactive oxygen intermediates and cytokine expression resulting in the chronic inflammatory state associated with autoimmune diseases.

Animals↗
PubMed1995

Exogenous myeloperoxidase enhances bacterial phagocytosis and intracellular killing by macrophages.

It is well documented that myeloperoxidase (MyPo) contributes to the bacterial activities of neutrophils and monocytes. Since mature macrophages (M phi) are devoid of this enzyme, its participation in M phi-mediated phagocytes and bacterial killing has not been completely defined. The present study demonstrates the exogenously added MyPo, at physiological levels, enhances both phagocytosis and killing of Escherichia coli. Murine peritoneal M phi were exposed to various concentrations of MyPo for different time intervals. Viable opsonized E. coli was added either prior to or after addition of MyPo. Thioglycolate-induced but not resident M pho exhibited an increase in the number of phagocytizing cells. Both resident and thioglycolate-induced M phi demonstrated increased bactericidal activity. Physiological levels of soluble MyPo also induced a significant increase in chemiluminescence. Since luminol-dependent chemiluminescence measures reactive oxygen intermediate production, studies were done to determine whether superoxide anion or H2O2 was involved in MyPo-induced M pho killing. Both superoxide dismutase and catalase ablated MyPo-induced bactericidal activity. The above data suggest that soluble MyPo, released from neutrophils at a site of infection or inflammation, can enhance both phagocytosis and killing of microorganisms.

Animals↗
PubMed1994

The effects of cocaine and its metabolites on the production of reactive oxygen and reactive nitrogen intermediates.

Cocaine, a naturally occurring alkaloid, is known to affect the immune system. The present authors have demonstrated that peritoneal macrophages, isolated from mice injected with cocaine, have an increased capacity for the production of reactive oxygen intermediates (ROI) and a decreased capacity for the production of reactive nitrogen intermediates (RNI). The present studies were done to determine the effects of certain cocaine metabolites on the induction of ROI and RNI by peritoneal macrophages. C57BL/6 mice were injected i.p. with either saline or 5 mg/kg of one of the following: cocaine, norcocaine, benzoylecgonine, ecgonine methyl ester HCl or ecgonine HCl. The ROI were measured using a chemiluminescence assay and the RNI were measured as nitrite secretion following exposure of isolated M phi to interferon gamma and LPS. Isolated peritoneal M phi from mice injected i.p. with cocaine, norcocaine and benzoylecgonine exhibited an increase in the production of ROI and a concomitant decrease in the production of RNI. However, injections of either ecgonine methylester HCl or ecgonine HCl had no effect on the induction of either ROI or RNI by murine peritoneal M phi. The cocaine metabolites, norcocaine and benzoylecgonine, have been reported to cause hepatic and/or cerebral toxicity. The present study also demonstrated that injection of these metabolites in vivo, also altered M phi functions which were measured in vitro.

Animals↗
PubMed1993

Cocaine alters the respiratory burst and phagocytic activity of murine macrophages.

The effects of cocaine on the respiratory burst (RB) and the phagocytic activity of murine macrophages (M phi) were studied. C57BL/6 mice were injected intraperitoneally with various concentrations of cocaine or appropriate vehicle. Peritoneal and alveolar M phi were isolated from mice and cultured in vitro. Both alveolar and peritoneal M phi from cocaine-exposed mice exhibited an increase in the RB when compared with M phi from saline-injected controls. This increase in the RB was apparent 60 min after injection and persisted for at least 48 hr. Injection of the cocaine metabolites, ecgonine methyl ester hydrochloride and ecgonine hydrochloride, did not affect the RB. The increase in the RB was correlated with an increase in phagocytosis of opsonized zymosan in vitro. However, an in vivo phagocytic assay using mice injected ip with cocaine, which was subsequently followed by sheep erythrocytes, demonstrated the opposite effect. Fewer peritoneal M phi from cocaine-injected mice were observed with ingested erythrocytes. These data underscore the complex effects of cocaine on M phi functions.

Animals↗
PubMed1993

Effects of cocaine on the respiratory burst of murine macrophages.

Cocaine is a central nervous stimulant with a major potential for abuse. It is used clinically as a local anesthetic and vasoconstrictor. The effects of cocaine on the immune system have not been studied in depth. In this study, we have investigated the effects of cocaine on the respiratory burst (RB) of murine macrophages (M phi). The RB was measured by determining the increase in chemiluminescence. Both peritoneal and alveolar M phi were isolated from cocaine-exposed mice and saline-exposed controls. Cocaine was administered by the intraperitoneal, intravenous, and intramuscular route. Both peritoneal and alveolar M phi from cocaine-exposed mice showed an increase in chemiluminescence when compared with M phi from matched controls. This effect was seen as early as one hour after cocaine exposure and lasted for up to 48 hours. Intraperitoneal injection of cocaine metabolites did not affect the RB. Macrophages exposed to cocaine in vitro failed to respond by an increase in RB. These findings indicate that cocaine induces the production of reactive oxygen intermediates (ROI) and suggests possible changes in M phi functions.

Animals↗
PubMed1993

The effects of alcohol on murine macrophage function.

Animal models used to measure the effects of alcohol on lymphoid cells and their functions provide useful ways to evaluate the multisystem effects of this substance. The effects of ethanol ingestion on the function of murine peritoneal macrophages (M phi) was evaluated. Both the production of reactive oxygen intermediates (ROI) and the ingestion of foreign particles (phagocytosis) were studied. Mice were pair fed ad libitum a nutritionally complete liquid diet containing 7% v/v ethanol or a calorically balanced control diet. Two regimens were employed for the administration of the diets. One regimen represented "binge" drinking (short term-4 days) while the other represented "chronic" consumption (long term-14 days). Following the short term administration of the diets, an increase in the respiratory burst (RB), as well as a decrease in phagocytosis, were observed with M phi from the ethanol fed mice. The decrease in phagocytosis, was noted using either in vitro or in vivo methods. Results observed after long term administration indicated no significant change in the RB or in in vitro phagocytosis between the ethanol and control groups. Phagocytosis measured in vivo, however, was decreased in M phi from ethanol fed mice following long term administration. These results indicate an alteration in murine peritoneal M phi function following short term an long term administration of alcohol.

Alcohol Drinking↗
PubMed1993

Regulation of macrophage function by human recombinant myeloperoxidase.

Myeloperoxidase is an enzyme which is found in the azurophilic granules of neutrophils and is associated with bactericidal, fungicidal, and tumoricidal activity. The present studies show that human recombinant myeloperoxidase (rec-MyPo) can regulate a number of macrophage (M phi) capacities and functions. Macrophages from mice exposed to rec-MyPo in vitro released reactive oxygen intermediates, tumor necrosis factor alpha (TNF alpha), and interferon alpha/beta (IFN alpha/beta). Enhanced target cell killing was also demonstrated with TNF alpha sensitive but not TNF alpha insensitive cells. Intravenous injection of rec-MyPo induced high titers of systemic TNF alpha and IFN alpha/beta. These results indicate that MyPo can function as an immunomodulator both in vitro and in vivo. Because of these actions, it is apparent that MyPo represents a previously unrecognized endogenous immunomodulator.

Adjuvants, Immunologic↗
PubMed1993

Cocaine reduces macrophage killing by inhibiting reactive nitrogen intermediates.

The present study describes the inhibition of macrophage-mediated cytotoxicity (MMC) by cocaine and suggests a possible mechanism. Mice (C57BL/6) were injected i.p. with cocaine. At various intervals after exposure to cocaine, peritoneal macrophages (M phi) were removed, cultured in the presence of interferon gamma and LPS, then incubated with 51Cr labeled target cells. A single injection of > or = 10 mg/kg cocaine was sufficient to inhibit cytotoxicity to P815 cells. This inhibition was evident 3 h after exposure to cocaine and could still be demonstrated 24 h later. Since reactive nitrogen intermediates (RNI) have been reported to be one of the major mechanisms by which M phi kill, the amounts of NO2- produced by M phi from cocaine-injected animals were compared with that produced by equivalent controls. Cocaine reduced the level of NO2- in a dose-dependent manner which correlated with MMC. There was a significant reduction in NO2- produced by activated M phi, 3 h after i.p. injection of cocaine but not at 24 h, using > or = 5 mg/kg. At 12 h there were differences between M phi from control animals and animals receiving > or = 10 mg/kg cocaine. By 24 h there were no differences between control and cocaine-injected animals even at the highest dose employed (25 mg/kg). These results suggest that cocaine reduces the killing ability of murine M phi through a temporary reduction of RNI.

Animals↗
PubMed1992

Macrophage activation and immunomodulation by myeloperoxidase.

Myeloperoxidase (MyPo) is an enzyme found in neutrophils and monocytes that plays an important role in the microbicidal and cytocidal activities of these cells. The present studies show that this enzyme can also affect both capacities and functions of macrophages. When resident peritoneal macrophages from C57BL/6 mice were exposed to preparations of either human or canine enzyme in vitro, tumor necrosis factor (TNF) was released. The amount of TNF produced was dose dependent and could be neutralized with polyclonal anti-TNF. Low levels of interferon were also produced by these cells. In addition, exposure of murine macrophages in vitro to this enzyme resulted in increased ability to destroy 3T12 target cells. Intravenous injection of mice with myeloperoxidase induced the production of both TNF and interferon, which could be detected in the sera. Possible mechanisms of TNF induction include radical production by myeloperoxidase or ligand-receptor interaction by the binding of this enzyme to the mannosyl-fucosyl receptor. These results, when taken in their entirety, suggest that this enzyme can modulate the immune response through effects on macrophage function.

Analysis of Variance↗
PubMed1992

Induction of interferon synthesis and cytotoxicity by murine peritoneal macrophages exposed to glycoprotein ligands.

Thioglycollate-induced murine C57BL/6 and C3H/HeN peritoneal macrophages synthesized interferon-beta (IFN-beta) in response to exposure to glycoproteins such as horseradish peroxidase (HRP) or mannosyl or fucosyl bovine serum albumin (BSAman of BSAfuc, respectively), but not glucosylated or galactosylated BSA (BSAglu or BSAgal, respectively). These results suggest participation of the mannosyl-fucosyl receptor (MFR) in this response. IFN synthesis was augmented by culturing macrophages in L cell-conditioned medium prior to exposure to these substances. Macrophages obtained from lipopolysaccharide (LPS)-resistant C3H/HeJ mice did not produce IFN in response to HRP. Furthermore, IFN-induction by HRP was blocked by polymyxin B. In addition, exposure of macrophages to HRP or BSAman induced cytotoxicity against NIH 3T12 cells. Cytotoxicity was not inhibited by the presence of anti-IFN-alpha/beta. In contrast to IFN induction, however, macrophages activation was LPS-independent, since this activity was demonstrated in macrophages from C3H/Hej mice. The carbohydrate specificity of these responses suggests that the MFR or an another scavenger receptor may be involved in the responses to these substances, and that cytotoxicity and IFN-induction by glycoproteins follow unique pathways.

Animals↗
PubMed1991

Induction of tumor necrosis factor and macrophage-mediated cytotoxicity by horseradish peroxidase and other glycosylated proteins: the role of enzymatic activity and LPS.

Recent studies by these investigators have shown that horseradish peroxidase (HRP) can cause murine thioglycollate-induced peritoneal macrophages (M phi) to produce both tumor necrosis factor (TNF) and enhance macrophage-mediated cytotoxicity (MMC) to 3T12 target cells. The present study identifies the roles of both enzymatic activity and contaminating lipopolysaccharides (LPS) (less than or equal to 1 ng) on these activities. The addition of 100 ng/ml of polymyxin B (PB) to enzymatically active HRP significantly reduced TNF production but did not affect MMC. Enzymatically inactive HRP (DHRP) was more effective than HRP in both TNF production and MMC but was not affected by PB. The inability of PB to modify DHRP-induced TNF suggests that LPS was not required. The induction of TNF and MMC in the absence of LPS was also corroborated by similar studies using M phi from endotoxin-resistant C3H/HeJ mice. Glycosylated proteins such as HRP, DHRP, and mannosylated bovine serum albumin (M-BSA) are known to bind to mannose receptors (mannosyl-fucosyl receptor [MFR]) on the surface of M phi. In the present studies, M-BSA behaved similarly to DHRP in that it induced both TNF secretion and MMC. These results suggest that binding to the MFR may be sufficient to induce TNF secretion and MMC. In addition, the data suggest that neither enzymatic activity nor LPS was required for DHRP-induced TNF.

Animals↗
PubMed1989

Peroxidases enhance macrophage-mediated cytotoxicity via induction of tumor necrosis factor.

Tumor necrosis factor (TNF) is a monokine which is involved in macrophage-mediated cytotoxicity (MMC). We have previously reported that peroxidases can activate thioglycollate-induced macrophages to the tumoricidal state in vitro. The present study was undertaken in an attempt to correlate peroxidase-induced MMC with production of TNF. Horseradish peroxidase (HRP) was used as the principal model for these studies. Resident and thioglycollate-induced macrophages exposed to peroxidases were examined for both MMC against 3T12 cells and production of TNF. Thioglycollate-induced macrophages exposed to HRP, bovine lactoperoxidase, or human myeloperoxidase demonstrated enhanced secretion of TNF. When exposed to HRP, both resident and thioglycollate-induced macrophages secreted significant amounts of TNF and acquired the ability to lyse 3T12 cells. However, resident macrophages were considerably less efficient in both their cytotoxic activity and TNF secretion. Macrophage-mediated cytotoxicity was eliminated by the addition of specific antisera to TNF. In addition, replacement of culture supernatants within 24 hr after exposure of the macrophages to HRP increased tumor cell killing in the absence of additional detectable TNF production, suggesting that other factors may be involved in peroxidase-induced MMC. These results indicate that TNF is intimately associated with peroxidase-induced MMC and suggest a possible role for peroxidases as immunomodulators via augmentation of macrophage capacities and functions.

Animals↗
PubMed1988

Peroxidase-induced enhancement of chemiluminescence by murine peritoneal macrophages.

A number of substances have been shown to enhance the respiratory burst (RB) of macrophages. Many of these substances are not normally found in vivo. The present study suggests that a group of enzymes characterized as peroxidases have the ability to significantly enhance the RB and concomitant phagocytosis by murine peritoneal macrophages. Horseradish peroxidase (HRP), lactoperoxidase (LPO), and microperoxidase (MPO) can significantly augment these functions. Both resident and thioglycollate-induced macrophages exhibited enhanced chemiluminescence (CL) upon exposure to HRP, however, the effect was more pronounced with the latter. The increase in CL was correlated with an increase in production of superoxide, which was measured by reduction of cytochrome c. Horseradish peroxidase immobilized on an inert carrier, was capable of enhancing the RB suggesting that it does not have to enter the cell in order to function. Hemin, hematoheme and hematoporphyrin had little effect on macrophage stimulated CL. All of the peroxidases tested caused increased phagocytosis of opsonized zymosan. These studies indicate that peroxidases are capable of stimulating the RB, phagocytosis and possibly other macrophage functions.

Animals↗
PubMed1988

The differential effects of calcium starvation on Duchenne muscular dystrophy fibroblasts.

The effects of nutrient deprivation on normal and Duchenne muscular dystrophy fibroblasts were examined. The requirements for Ca2+ and fetal bovine serum were assessed by their effects on the cells' ability to support viral replication, and by ability of the cells to divide in the presence of low levels of these nutrients. When grown in Ca2+-deficient media, Duchenne fibroblasts supported viral replication at a rate 2- to 2.5-fold greater than did normal fibroblasts. At normal Ca2+ levels, Duchenne fibroblasts supported viral replication at levels slightly lower than their normal counterparts. After 48 hr in medium containing 0.2 mM Ca2+, the growth of normal cells was arrested, while Duchenne fibroblasts were relatively unaffected. When grown in medium containing either 0.2 or 2.0% serum, the growth of normal cells was arrested within 48 hr, with cell death occurring within 72 hr. Duchenne fibroblasts continued to divide at these serum levels for 72 hr, reaching higher cell densities than normal cells. These results suggest that a defect related to Ca2+ metabolism may be part of the Duchenne phenotype, which could be used to identify Duchenne muscular dystrophy cells.

Calcium↗
PubMed1986

Effects of NO2 on immune responses.

The effects of NO2 on immune responses of mice were investigated. Mice were exposed to various concentrations of NO2 in inhalation chambers. After exposure the following parameters were measured: phagocytosis of polystyrene beads by both peritoneal and alveolar macrophages, production of antibody-forming cells from mice immunized with sheep erythrocytes, lymphocyte blastogenesis of splenic cells, and susceptibility to influenza virus. The production of antibody-forming cells was reduced in mice that were exposed to 5 ppm NO2. The serum antibody titers, phagocytosis, and other immune parameters measured were not affected. Exposure to NO2 did not affect mortality to influenza virus. These data indicate that certain immune parameters were altered by exposure to NO2; however, NO2 does not appear to be a major immunosuppressive factor at the concentrations tested.

Animals↗
PubMed1986

Activation of macrophages by peroxidases.

Peritoneal macrophages from C57BL/6 mice were activated in vitro with various peroxidases and their cytotoxic activity toward 3T12 cells was determined. Destruction of 3T12 cells by macrophages stimulated with horseradish peroxidase, lactoperoxidase, and microperoxidase was observed at peroxidase concentrations as low as 9, 1.6, and 200 nM, respectively. A 50% cytotoxic effect was obtained at peroxidase concentrations of 0.9, 1.6, and 1.5 microM, respectively. The macrophage-stimulating activity of horseradish peroxidase was not destroyed by boiling. This, together with the high activity of microperoxidase, indicates that the macrophage-stimulating activity of the peroxidases is probably associated with the heme portion of the enzymes. On a molar basis the peroxidases are much less potent macrophage activators than interferon (alpha + beta) and endotoxin. Nevertheless, our data clearly indicate that peroxidases are a group of enzymes capable of inducing macrophage activation, resulting in cytostatic and/or cytocidal activity.

Animals↗