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Biomedical subjects

F Kierszenbaum

Publications and source records attributed to F Kierszenbaum.

At least 109 records · Page 6Linked to original sources
PubMed1984

Fibronectin enhances macrophage association with invasive forms of Trypanosoma cruzi.

Treatment of either mouse peritoneal macrophages (MPH) or invasive blood forms of Trypanosoma cruzi with human plasma fibronectin (FN) significantly enhanced their association (a term to mean surface attachment and parasite internalization) with the untreated counterpart in a dose-dependent manner. This effect involved increases in the percentage of MPH that associated with the parasites and in the number of parasites per MPH. By using indirect immunofluorescence, the percentages of FN-positive MPH and FN-positive parasites found in preparations of these cells were 26 and 13%, respectively, and increased to 70 and 73%, respectively, after incubation with FN for 60 min and multiple washings. These results demonstrated the presence of FN itself and FN-binding sites on the surface of MPH and T. cruzi. Incubation of FN-treated MPH and FN-treated parasites with gelatin, for which FN has a binding site, significantly reduced the stimulatory effect of FN. A reduction was also seen when FN-treated MPH were incubated with anti-FN antibody before adding the parasites. These observations suggested that FN might enhance association by bridging the interacting cells. The presence of excess soluble FN during MPH-parasite interaction also inhibited the association, possibly by blocking FN receptors on the MPH and parasite surfaces. Pretreatment of the MPH with FN enhanced the capacity of these cells to associate with either untreated latex beads or killed T. cruzi. These findings indicated, on the one hand, that the FN-mediated enhancement was not unique to living T. cruzi and, on the other, that this enhancement was not likely due to an FN-induced alteration of the MPH membrane that would render it more susceptible to active penetration by the parasites. Taken together, these results suggest that FN, produced by MPH, may play a role in infection of this cell type by T. cruzi.

Adjuvants, Immunologic↗
PubMed1984

Effects of treatment of trypomastigote forms of Trypanosoma cruzi or host cells with ethidium bromide on cell infection and intracellular fate of the parasite.

The effects of treatment of virulent blood forms of Trypanosoma cruzi with ethidium bromide (EtBr)-an intercalating drug that inhibits DNA synthesis-on parasite association with (a term to mean surface binding plus internalization) and multiplication within different types of host cells were investigated. EtBr markedly reduced the extent of T. cruzi association with Vero cells or rat heart myoblasts (RHM) as evidenced by significant decreases in both the number of flagellates per cell and the percentage of infected cells with respect to control values obtained with organisms treated with medium alone. In contrast, treatment of Vero cells with EtBr had no significant consequence on the extent of cell-T. cruzi association and did not affect the capacity of the parasites to transform into amastigotes and multiply intracellularly. Very few organisms were able to gain access to the cytoplasms of the host cells after treated with 1 X 10(-5) M EtBr but these were virtually unable to multiply intracellularly. Parasites treated with 1 X 10(-6) M EtBr multiplied at a slower rate than medium-treated organisms. Unlike untreated trypomastigotes, parasites treated with 1 X 10(-5) M EtBr were unable to transform into amastigotes in a cell-free medium that supported the growth of untreated organisms. A marked reduction in the rate of amastigote multiplication was seen in cells with an established infection when they were treated with EtBr. These results suggest that ongoing DNA synthesis by T. cruzi is required for it to effectively bind and infect host cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Beta-interferon inhibits cell infection by Trypanosoma cruzi.

Preparations containing alpha/beta-interferon produced by L-929 cells were found to inhibit the capacity of bloodstream forms of Trypanosoma cruzi to associate with and infect mouse peritoneal macrophages or rat heart myoblasts. Marked reductions in the number of parasites per cell as well as in the percentage of cells associated with the trypanosomes were systematically observed in cultures of these cells that contained interferon. The inhibitory effect was abrogated in the presence of specific antibodies against alpha/beta-interferon, and purified beta-interferon induced a similar inhibitory effect, indicating that the active principle in the preparation was indeed interferon. Pretreatment of the parasites with alpha/beta-interferon reduced their infectivity for untreated host cells, whereas pretreatment of either type of host cell had no consequence on the interaction. The effect of interferon on the trypanosomes was reversible; the extent of the inhibitory effect was significantly reduced after 20 min, and was undetectable after 60 min when macrophages were used as host cells. Longer periods of time were required for the inhibitory effect to begin to subside (60 min) and to become undetectable or insignificant (120 min) when rat heart myoblasts were used. The results of additional studies performed with purified preparations of alpha- or beta-interferon revealed that only the latter was inhibitory of cell-parasite association. Because interferon is known to be produced shortly after T. cruzi infection and its administration has been shown to have a marked protective effect against this infection, our results suggest that the latter may involve inhibition of cell infection by interferon.

Animals↗
PubMed1984

Role of inflammatory cells in Chagas' disease. I. Uptake and mechanism of destruction of intracellular (amastigote) forms of Trypanosoma cruzi by human eosinophils.

The ability of human eosinophils (EOS) to take up and kill intracellular (amastigote, AMA) forms of Trypanosoma cruzi was investigated as a part of our efforts to define the role of inflammatory cells, typically found in acute chagasic lesions, in clearance and destruction of the parasite. In experiments in which purified EOS and AMA were mixed and allowed to interact for 1 hr, EOS uptake of the parasites was demonstrable by electron microscopy and was confirmed by measurements of incorporation of [3H]AMA. The degree of parasite uptake increased with the AMA to EOS ratio, and was detectable as early as 20 min after the initial contact. After 1 hr, a time when minimal AMA damage was noted, 40% of the EOS were found to contain parasites. Damage inflicted on the AMA was frequently seen 2 hr after removal of free AMA; largely destroyed parasites were a common occurrence after 4 hr. The electron microscopic observations were confirmed by kinetic measurements of the release of 3H-labeled materials by EOS that had ingested radiolabeled AMA. The AMA were systematically found within the EOS vacuoles and were never seen free in the cytoplasm. Fusion of the EOS granules with AMA-containing vacuoles was frequently observed and the presence of EOS granule major basic protein (MBP) in the vacuole content was demonstrated immunocytochemically. MBP was around the AMA and bound to parasite structures, including the subpellicular microtubules. Heparin, a polyanion previously shown to abrogate MBP-mediated destruction of blood forms of T. cruzi, inhibited intracellular killing of AMA by EOS. Two other polyanions, chondroitin sulfate and dextran sulfate, had similar effects. In an EOS-free system, the presence of MBP resulted in AMA lysis; this reaction was inhibited by anti-MBP antibody. Taken together, these results favor the notion that EOS contribute to the elimination of T. cruzi AMA from infected tissues through phagocytosis, leading to an intravacuolar lytic process in which at least MBP plays a role.

Animals↗
PubMed1984

Role of inflammatory cells in Chagas' disease. II. Interactions of mouse macrophages and human monocytes with intracellular forms of Trypanosoma cruzi: uptake and mechanism of destruction.

In this study we examined the kinetics of interaction between mouse peritoneal macrophages (MPH) or human blood monocytes (HBM) with intracellular (amastigote [AMA]) forms of Trypanosoma cruzi. In electron microscopy studies, AMA were seen bound to the surface of unelicited MPH after 5 min of interaction, i.e., when the first observations were made. Internalization was visible after 8 min, and the AMA were never seen outside of phagocytic vacuoles. Signs of AMA damage were first seen after 4 hr. Amastigote disintegration was commonly observed 12 hr after their initial contact with MPH. Similar results were obtained with HBM. These kinetic patterns of AMA uptake and destruction were in agreement with the results of quantitative assays in which the number of AMA contained by 200 MPH and the percentage of infected MPH were measured. The extent of the release of 3H-labeled materials from MPH that had phagocytosed [3H]AMA was approximately 10, 90, and 99% of the total ingested radioactivity after 4, 12, and 24 hr of incubation, respectively. A comparison of the kinetic patterns of MPH interaction with noninvasive AMA and invasive trypomastigote (TRY) forms showed that, after internalization, both the percentage of AMA-containing MPH and the number of AMA per 200 MPH declined dramatically over a 70-hr incubation period, whereas the percentage of MPH infected by the TRY remained virtually constant and the number of organisms per 200 cells increased markedly. This contrast indicated that the AMA had been destroyed, whereas the TRY had managed to survive, transform into AMA, and multiply within MPH. AMA killing by MPH involved H2O2 but not other intermediates of oxygen reduction, because it was inhibited by catalase but not by scavengers of O2, OH ., and 1O2. AMA lost their viability when incubated with glucose and glucose oxidase, confirming their sensitivity to H2O2. Thus, MPH and HBM have the potential for participating in the clearance of T. cruzi AMA from chagasic tissue lesions.

Animals↗
PubMed1983

Role of cell surface mannose residues in host cell invasion by Trypanosoma cruzi.

The role of mannose residues on the membranes of Trypanosoma cruzi and its host cells in their association (surface binding plus internalization of the parasite) leading to infection was studied. Used in this work were the bloodstream (trypomastigote), intracellular (amastigote) and insect-transmissible (metacyclic trypomastigote) forms of the parasite; mouse macrophages and rat heart myoblasts were used as the host cells. Removal of mannose residues from the surface of all forms of the parasite by treatment with alpha-mannosidase produced a marked increase in their respective abilities to associate with either host cell. The increase was more pronounced with the bloodstream and insect-derived trypomastigotes (which can penetrate cell membranes) than with the amastigotes (which can not do so). By contrast, mannosidase treatment of the macrophages and the myoblasts caused a significant decrease in the ability of these cells to associate with either bloodstream or insect-derived trypomastigote forms. The capacity of mannosidase-treated macrophages to take up the non-invasive amastigotes was also reduced. These results, as a whole, suggest that mannose residues on the surface of the parasite modulate their binding to macrophages and myoblasts and that mannose residues on the surface of these host cells play a role in cell association with the parasite.

Animals↗
PubMed1983

Cross-reactivity of vector-borne metacyclic forms of Trypanosoma cruzi with mammalian and culture stages.

Metacyclic forms of Trypanosoma cruzi isolated from the hindgut of infected insect vectors (Rhodnius prolixus) were found to be immunologically cross-reactive with cultured epimastigote, amastigote, and metacyclic stages of the parasite as well as with bloodstream trypomastigote forms by direct agglutination and indirect immunofluorescence techniques. Sera specific for each of these forms of the parasite systematically yielded maximal antibody titers when measured against the homologous antigen, indicating that antigenic determinants are shared by all of the developmental forms used in this work. Supporting this conclusion were the significant reductions in anti-insect-derived metacyclic antibody titer caused by absorption with any of the other life stages of T. cruzi. These results are relevant to the potential use of laboratory-grown forms of T. cruzi in vaccination against a natural infection with this parasite.

Agglutination Tests↗
PubMed1983

Helper function of rat spleen cells reactive with guinea pig serum.

Treatment of rat spleen cells with normal guinea pig serum (GPS) has been shown to produce a significant loss of responsiveness to stimulation with either Con A or PHA. This phenomenon was seen even when the spleen cells were triggered with mitogens up to 96 hr after treatment with GPS, suggesting that GPS had produced a long-lasting alteration in some cells or removed a cell subpopulation. Glass-wool non-adherent spleen cells, known to produce greater responses that unfractionated spleen cells, also had their responses to Con A and PHA reduced by GPS treatment though the response was still greater than that of untreated, unfractionated cells, suggesting that the actual responder cells had been spared by GPS. Suppressor cells did not appear to be the target of GPS because such an effect would have resulted in increased responsiveness and the opposite result was obtained. That a helper cell was affected by GPS was suggested by the following observations: a) the virtually unresponsive GPS-treated spleen cells produced greater than normal responses after removal of glass-wool-adherent suppressor cells; b) the response of glass-wool-nonadherent spleen cells was significantly decreased after GPS treatment; and c) mixtures containing equal numbers of glass-wool-nonadherent and GPS-treated spleen cells also showed reduced responsiveness after GPS treatment.

Animals↗
PubMed1983

Susceptibility of insect-borne, metacyclic forms of Trypanosoma cruzi to antibody-mediated mechanisms of destruction.

The effect of passive antibody transfer against infection with vector-borne, metacylic forms of Trypanosoma cruzi, and possible mechanisms of immunologic lysis of these organisms, were examined in this work. Anti-T. cruzi antibodies from mice surviving an infection conferred marked protection against challenge with a lethal dose (2,000 organisms) of metacyclic flagellates isolated from the reduviid insect Rhodnius prolixus. In vitro lysis of these parasites by immune sera from mice or chronic chagasic patients was found to require complement (C) activity since the phenomenon was abrogated by heating the sera at 56 degrees C, adding the C inactivator cobra venom factor or in the absence of divalent cations. The lytic activity was provided via the alternative pathway of C activation since it was readily demonstrable in the absence of calcium ions. The metacyclic trypanosomes were also killed by human lymphocytes, neutrophils and eosinophils in the presence of anti-T. cruzi antibodies. Minimal or insignificant cytotoxicity was afforded by the cells or the antibodies when tested separately. These results emphasize the beneficial role of the humoral immune response in host defense against challenge with the form of T. cruzi responsible for natural infections.

Animals↗
PubMed1983

Immunization against a challenge with insect vector, metacyclic forms of Trypanosoma cruzi simulating a natural infection.

The protective effects of immunization with an antigen derived from epimastigote forms of Trypanosoma cruzi against challenges with vector metacyclic or bloodstream forms of the parasite were investigated. A marked degree of protection was observed in the immunized mice after challenged with bloodstream or insect-transmissible metacyclic forms. High rates of survival in the immunized groups were accompanied by relatively low, shortlasting parasitemias in some of the animals and significant percentages of immunized mice never developed a measurable parasitemia during the course of the experiments. In contrast, all of the non-immunized animals showed high levels of parasitemias. Similar results were obtained whether the metacyclic challenge was by the intraperitoneal or by the ocular route for which conditions mimicking a natural infection were selected. These results emphasize the protection that immunization confers against challenge with insect-transmissible forms of T. cruzi, and the feasibility of protecting a highly susceptible host against an otherwise lethal acute infection similar to one occurring naturally.

Animals↗
PubMed1983

Role of polymorphonuclear cells in Chagas' disease. I. Uptake and mechanisms of destruction of intracellular (amastigote) forms of Trypanosoma cruzi by human neutrophils.

The ability of human polymorphonuclear cells (PMN) to take up and destroy intracellular forms of Trypanosoma cruzi (AMA) was investigated as a part of our efforts to elucidate the mechanisms of clearing of these parasites from infected tissues. PMN were found to take up AMA and destroyed parasites were seen after 30 min of cell-parasite interaction. Under our experimental conditions, the rate of uptake of AMA by PMN was maximal during the first 30 min of interaction. AMA were found to be located and destroyed inside the phagolysosomal vacuoles of PMN. The parasite was never found outside these vacuoles despite electron microscopic examination of numerous preparations derived from several experiments. Intracellular destruction of AMA by PMN was visible by electron microscopy and could be monitored by measuring the release of 3H-labeled substances by PMN that had ingested radiolabeled AMA. PMN incubated after removal of unbound parasites destroyed over 90% of the ingested organisms within 3 hr and close to 99% after 12 hr. In cellfree systems, 44% of the AMA were destroyed in the presence of 10(-4) M H2O2 and all of the parasites died at 10(-3) M. Addition of lactoperoxidase and iodide resulted in 100% killing at 10(-5) M H2O2. These mechanisms appeared to be involved in the lysis of AMA by PMN since both H2O2 and peroxidase activity were demonstrated to be present in PMN vacuoles containing the parasite. Addition of NaN3, KCN (inhibitors of myeloperoxidase activity) or catalase (to decompose H2O2) caused a marked reduction in the extent of AMA killing by PMN. Xanthine oxidase was toxic for the AMA in the presence of acetaldehyde. This microbicidal activity was inhibited by catalase but not by heat-inactivated catalase or by reagents that scavenge the intermediate products of reduction of molecular oxygen, O - X 2, X OH, and 1O2. These results suggest that PMN have the potential of clearing AMA liberated in infected chagasic tissues and that parasite killing within the phagolysosomal vacuoles is mediated by myeloperoxidase activity and H2O2.

Animals↗
PubMed1983

Modulatory effect of guanosine-3':5' cyclic monophosphate on macrophage susceptibility to Trypanosoma cruzi infection.

The effects of agents that elevate intracellular levels of cGMP on macrophage internalization of the unicellular parasite Trypanosoma cruzi and latex particles were examined in an attempt to define characteristics of the infective process. Presence of imidazole, a drug that prevents degradation of the cGMP by inhibiting cGMP phosphodiesterase activity, during macrophage-T. cruzi interaction resulted in a marked increase in the number of parasites associated with the cells and the percentage of infected cells. Similar results were obtained when sodium nitroprusside (SNP), which increases cGMP levels by an as yet undefined mechanism, dibutyryl-cGMP, or both imidazole and dibutyryl-cGMP were added to the system. In contrast, the presence of imidazole, SNP, or dibutyryl-cGMP had no significant consequence on latex particle uptake by the macrophages. Whereas pretreatment of macrophages with imidazole plus dibutyryl-cGMP readily increased T. cruzi infection, pretreatment of the parasite with these drugs had no significant effect on the interaction. Furthermore, results of radioimmunoassays showed that imidazole and SNP indeed elevated cGMP levels in the macrophages but not in the parasites. Taken together, these results indicate that cGMP plays a facilitating role in macrophage infection by T. cruzi that contrasts with the lack of effect on the uptake of inert latex particles and the previously reported inhibitory effect of cAMP in the same system. Thus, cyclic nucleotides appear to play a role in modulating internalization of the parasite but not in the uptake of an inert particle by macrophages.

Animals↗
PubMed1983

Trypanosoma cruzi: differences in cell surface interaction of circulating (trypomastigote) and culture (epimastigote) forms with macrophages.

Characteristics of the association of circulating (trypomastigote) and cultured (epimastigote) forms of Trypanosoma cruzi with macrophages were studied. Treatment of mouse macrophages with the anti-microfilament drug cytochalasin D severely reduced the ability of these cells to bind either trypomastigotes or epimastigotes. Instead, treatment with the antimicrotubule drug colchicine or 2-deoxyglucose afforded differential effects because epimastigote but not trypomastigote association with the macrophages was significantly inhibited. Prior treatment of epimastigotes with either trypsin or neuraminidase decreased their uptake by macrophages whereas treatment of trypomastigotes with either enzyme increased it. Pretreatment of macrophages with neuraminidase did not affect epimastigote uptake but reduced that of trypomastigotes. Pretreatment of macrophages with trypsin reduced the uptake of both forms of the parasite. However, quantitative differences in the extent of such reduction were noted when varying concentrations of trypsin were used, epimastigote uptake being more drastically affected. These results suggest that the initial interaction of virulent circulating trypomastigote and the attenuated cultured epimastigote forms of T. cruzi to macrophages may involve attachment via different surface structures.

Animals↗
PubMed1983

Inhibition of mitogen-induced proliferation of mouse T and B lymphocytes by bloodstream forms of Trypanosoma cruzi.

The role of virulent forms of Trypanosoma cruzi in modulating mitogen-induced lymphocyte responses was investigated in this work. Bloodstream forms of T. cruzi inhibited normal mouse spleen cell responses to Con A and LPS in a dose-dependent manner. Reduced responses were observed over relatively large ranges of concentration of Con A (50-fold) and LPS (160-fold). The inhibitory action of the parasites could not be overcome by increasing the mitogen dose beyond optimal levels. Furthermore, absorption of mitogen solutions with four times as many parasites as used in the proliferation assays revealed that sufficient mitogen activity remained to produce optimal lymphocyte responses. Therefore, reduced lymphocyte responsiveness was not due to absorption of mitogen by the parasite. Inhibited responses were also seen when a sonicated T. cruzi preparation was used, indicating that parasite viability was not required to produce suppression. Inhibition of Con A- or LPS-induced responses by the parasites occurred only when the trypanosomes were incorporated into the system during the first 24 hr of culture. These results show that virulent forms of T. cruzi can induce suppression of T and B cell responses in vitro, and suggest that the parasite affects lymphocyte commitment to blastogenesis during the early stages of lymphocyte activation.

Animals↗