Antitumor effects and hematotoxicity of C60-Cis-Pt nanocomplex in mice with Lewis lung carcinoma

BACKGROUND

Cisplatin (Cis-Pt) is a widely used anticancer drug but its therapeutic efficiency is limited by hemato-, cardio-, hepato-, nephro- and neurotoxicity. Complexation of Cis-Pt with C₆₀ fullerene nanoparticle will allow to enhance the antitumor activity of the drug and to reduce its side toxic effects.

AIM

To estimate the antitumor effects of С60-Cis-Pt nanocomplex in Lewis lung carcinoma (LLC) and analyze hematological toxicity in tumor-bearing mice.

MATERIALS AND METHODS

Complexation of C₆₀ fullerene and Cis-Pt molecule was studied by computer simulation. С60-Cis-Pt nanocomplex was i.p. injected to LLC-bearing mice in a total dose of 7.5 mg/kg (C₆₀:Cis-Pt as 3.75:3.75 mg/kg). The survival of tumor-bearing mice and the relative reduction of tumor weight was recorded. Blood indices were determined using the Particle Counter PCE-210 automatic hematology analyzer.

RESULTS

Computer simulation demonstrated the formation of С60-Cis-Pt nanocomplex in physiological medium and its stability due to the hydrophobic interactions. Treatment with C₆₀-Cis-Pt nanocomplex increased survival time of LLC-bearing mice by 32%, normalized hemoglobin content (up to 100 g/l), erythrocyte and platelet count as compared to the untreated LLC-bearing mice. Tumor weight decreased by 35.5%; the mitotic index of tumor cells decreased by 78%, and apoptotic index increased by 75%. The revealed effects of the C₆₀-Cis-Pt nanocomplex were more pronounced than the effects of Cis-Pt or C₆₀ fullerene alone in equivalent dose.

CONCLUSION

Treatment with C₆₀-Cis-Pt nanocomplex prolonged the survival of LLC-bearing mice and reduced anemia in LLC-bearing mice.

Fullerene C60 Penetration into Leukemic Cells and Its Photoinduced Cytotoxic Effects

Fullerene C₆₀ as a representative of carbon nanocompounds is suggested to be promising agent for application in photodynamic therapy due to its unique physicochemical properties. The goal of this study was to estimate the accumulation of fullerene C₆₀ in leukemic cells and to investigate its phototoxic effect on parental and resistant to cisplatin leukemic cells. Stable homogeneous water colloid solution of pristine C₆₀ with average 50-nm diameter of nanoparticles was used in experiments. Fluorescent labeled C₆₀ was synthesized by covalent conjugation of C₆₀ with rhodamine B isothiocyanate. The results of confocal microscopy showed that leukemic Jurkat cells could effectively uptake fullerene C₆₀ from the medium. Light-emitting diode lamp (100 mW cm^-2, λ = 420-700 nm) was used for excitation of accumulated C₆₀. A time-dependent decrease of viability was detected when leukemic Jurkat cells were exposed to combined treatment with C₆₀ and visible light. The cytotoxic effect of photoexcited C₆₀ was comparable with that induced by H₂O₂, as both agents caused 50% decrease of cell viability at 24 h at concentrations about 50 μM. Using immunoblot analysis, protein phosphotyrosine levels in cells were estimated. Combined action of C₆₀ and visible light was followed by decrease of cellular proteins phosphorylation on tyrosine residues though less intensive as compared with that induced by H₂O₂ or protein tyrosine kinase inhibitor staurosporine. All tested agents reduced phosphorylation of 55, 70, and 90 kDa proteins while total suppression of 26 kDa protein phosphorylation was specific only for photoexcited C₆₀.The cytotoxic effect of C₆₀ in combination with visible light irradiation was demonstrated also on leukemic L1210 cells both sensitive and resistant to cisplatin. It was shown that relative value of mitochondrial membrane potential measured with tetramethylrhodamine ethyl ester perchlorate (TMRE) probe was lower in resistant cells in comparison with sensitive cells and the drop of mitochondrial potential corresponded to further decrease of resistant cell viability after C₆₀ photoexcitation. The data obtained allow to suggest that C₆₀-mediated photodynamic treatment is a candidate for restoration of drug-resistant leukemic cell sensitivity to induction of mitochondrial way of apoptosis.

Cytotoxic Effects of Dimorfolido-N-Trichloroacetylphosphorylamide and Dimorfolido-N-Benzoylphosphorylamide in Combination with C60 Fullerene on Leukemic Cells and Docking Study of Their Interaction with DNA

Dimorfolido-N-trichloroacetylphosphorylamide (HL1) and dimorfolido-N-benzoylphosphorylamide (HL2) as representatives of carbacylamidophosphates were synthesized and identified by the methods of IR, ¹H, and ³¹P NMR spectroscopy. In vitro HL1 and HL2 at 1 mM concentration caused cell specific and time-dependent decrease of leukemic cell viability. Compounds caused the similar gradual decrease of Jurkat cells viability at 72 h (by 35%). HL1 had earlier and more profound toxic effect as compared to HL2 regardless on leukemic cell line. Viability of Molt-16 and CCRF-CEM cells under the action of HL1 was decreased at 24 h (by 32 and 45%, respectively) with no substantial further reducing up to 72 h. Toxic effect of HL2 was detected only at 72 h of incubation of Jurkat and Molt-16 cells (cell viability was decreased by 40 and 45%, respectively).It was shown that C₆₀ fullerene enhanced the toxic effect of HL2 on leukemic cells. Viability of Jurkat and CCRF-CEM cells at combined action of C₆₀ fullerene and HL2 was decreased at 72 h (by 20 and 24%, respectively) in comparison with the effect of HL2 taken separately.In silico study showed that HL1 and HL2 can interact with DNA and form complexes with DNA both separately and in combination with C₆₀ fullerene. More stable complexes are formed when DNA interacts with HL1 or C₆₀ + HL2 structure. Strong stacking interactions can be formed between HL2 and C₆₀ fullerene. Differences in the types of identified bonds and ways of binding can determine distinction in cytotoxic effects of studied compounds.

C60 Fullerene as Promising Therapeutic Agent for the Prevention and Correction of Skeletal Muscle Functioning at Ischemic Injury

The therapeutic effect of pristine C60 fullerene aqueous colloid solution (C60FAS) on the functioning of the rat soleus muscle at ischemic injury depending on the time of the general pathogenesis of muscular system and method of administration C60FAS in vivo was investigated. It was found that intravenous administration of C60FAS is the optimal for correction of speed macroparameters of contraction for ischemic muscle damage. At the same time, intramuscular administration of C60FAS shows pronounced protective effect in movements associated with the generation of maximum force responses or prolonged contractions, which increase the muscle fatigue level. Analysis of content concentration of creatine phosphokinase and lactate dehydrogenase enzymes in the blood of experimental animals indicates directly that C60FAS may be a promising therapeutic agent for the prevention and correction of ischemic-damaged skeletal muscle function.

Comparative Analysis of the Antineoplastic Activity of C60 Fullerene with 5-Fluorouracil and Pyrrole Derivative In Vivo

The antitumor activity of pristine C60 fullerene aqueous solution (C60FAS) compared to 5-fluorouracil (5-FU) and pyrrole derivative 1-(4-Cl-benzyl)-3-Cl-4-(CF3-fenylamino)-1H-pyrrol-2.5-dione (MI-1) cytostatic drugs was investigated and analyzed in detail using the model of colorectal cancer induced by 1.2-dimethylhydrazine (DMH) in rats. The number, size, and location of the tumors were measured, and the pathology was examined. It was found that the number of tumors and total lesion area decreased significantly under the action of C60FAS and MI-1. Because these drugs have different mechanisms of action, their simultaneous administration can potentially increase the effectiveness and significantly reduce the side effects of antitumor therapy.

Structural self-organization of C60 and cisplatin in physiological solution

The specific features of structural self-organization of C60 fullerene and antitumor drug cisplatin (Cis) in physiological solution (0.9% NaCl) have been investigated by means of small-angle neutron scattering, scanning electron and atomic force microscopies, as well as isothermal titration calorimetry, dynamic light scattering and UV-Vis spectroscopy. The formation of C60 + Cis complexes, has been reported, unveiling the mechanism of medico-biological synergy observed during administration of the mixture of these drugs.

Photocytotoxic effect of C60 fullerene against L1210 leukemic cells is accompanied by enhanced nitric oxide production and p38 MAPK activation

AIM

To estimate the combined action of C60 fullerene and light irradiation on viability of L1210 leukemic cells, nitric oxide (NO) generation, p38 mitogen-activated protein kinase (MAPK) activity and cell cycle distribution.

METHODS

Cell viability was assessed by MTT test. Light-emitting diode lamp (λ = 410-700 nm, 2.45 J/cm(2) ) was used for C60 fullerene photoexcitation. Nitrite level and NO-synthase activity were measured by Griess reaction and by conversion of L-arginine to L-citrulline, respectively. p38 MAPK activity was assessed by Western blot analysis. Cell cycle distribution was determined by flow cytometry.

RESULTS

It was shown that light irradiation of C60 fullerene-treated L1210 cells was accompanied by 55% decrease of their viability at 48 h of culture. Nitrite level measured as an index of reactive NO generation was increased at the early period after C60 fullerene photoexcitation due to activation of both constitutive and inducible NO-synthase isoforms. The simultaneous activation of p38 MAPK was detected. Accumulation of L1210 cells in sub-G1 phase of cell cycle was observed after C60 fullerene photoexcitation.

CONCLUSION

Photoexcited C60 fullerene exerts cytotoxic effect, at least in part, through triggering production of reactive NO species and activation of p38 kinase apoptotic pathways in L1210 leukemic cells.

Hepatoprotective effect of orally applied water-soluble pristine C60 fullerene against CCl4-induced acute liver injury in rats

Oral administration of water-soluble pristine C₆₀ fullerene in small dose prevents acute liver injury caused by carbon tetrachloride in rats.

Study of the complexation between Landomycin A and C60 fullerene in aqueous solution

We report here the first investigation of the non-covalent complexation between C₆₀ fullerene and angucycline antibiotic Landomycin A.

Characterization of C60 fullerene complexation with antibiotic doxorubicin

The aim of this paper was to provide the physico-chemical characterization of a key process leading to amplification of the antitumor effect of antibiotic Doxorubicin (Dox) in vivo and in vitro and occurring at the molecular level through complexation with C60 fullerene. A wide range of physico-chemical tools was used such as UV/Vis and NMR spectroscopies, atomic force microscopy, isothermal titration calorimetry and zeta-potential methods. The unusual thermodynamic behavior of the complexation process was reported, featuring unexpected and, to a certain extent, contradictory experimental observations. The explanation of the obtained results was proposed resulting in creation of a general view on aromatic drug binding with C60 fullerene. Based on these results some important practical outcomes for anticancer therapy were formulated.

Impact of C 60 fullerene on the dynamics of force-speed changes in soleus muscle of rat at ischemia-reperfusion injury

The effect of C60 fullerene nanoparticles (30-90 nm) on dynamics of force response development to stimulated soleus muscle of rat with ischemic pathology, existing in muscle during the first 5 hours and first 5 days after 2 hours of ischemia and further reperfusion, was investigated using the tensometric method. It was found that intravenous and intramuscular administration of C60 fullerene with a single dose of 1 mg/kg exert different therapeutic effects dependent on the investigated macroparameters of muscle contraction. The intravenous drug administration was shown to be the most optimal for correction of the velocity macroparameters of contraction due to muscle tissue ischemic damage. In contrast, the intramuscular administration displays protective action with respect to motions associated with generation of maximal force response or continuous contractions elevating the level of muscle fatigue. Hence, C60 fullerene, being a strong antioxidant, may be considered as a promising agent for effective therapy of pathological states of the muscle system caused by pathological action of free radical processes.

Application of C60 Fullerene-Doxorubicin Complex for Tumor Cell Treatment In Vitro and In Vivo

Development of nanocarriers for effective drug delivery to molecular targets in tumor cells is a real problem in modern pharmaceutical chemistry. In the present work we used pristine C60 fullerene as a platform for delivery of anticancer drug doxorubicin (Dox) to its biological targets. The formation of a complex of C60 fullerene with Dox (C60 + Dox) is described and physico-chemical characteristics of such complex are presented. It was found that Dox conjugation with C60 fullerene leads to 1.5-2-fold increase in Dox toxicity towards various human tumor cell lines, compared with such effect when the drug is used alone. Cytotoxic activity of C60 + Dox complex is accompanied by an increased level of cell produced hydrogen peroxide at early time point (3 h) after its addition to cultured cells. At the same time, cellular production of superoxide radicals does not change in comparison with the effect of Dox alone. Cytomorphological studies have demonstrated that C60 + Dox complexes kill tumor cells by apoptosis induction. The results of in vivo experiments using Lewis lung carcinoma in mice confirmed the enhancement of the Dox toxicity towards tumor cells after drug complexation with C60 fullerene. The effect of such complex towards tumor-bearing mice was even more pronounced than that in the in vitro experiment with targeting human tumor cells. The tumor volume decreased by 2.5 times compared with the control, and an average life span of treated animals increased by 63% compared with control. The obtained results suggest a great perspective of application of C60 + Dox complexes for chemotherapy of malignant tumors.

C60 fullerene prevents genotoxic effects of doxorubicin in human lymphocytes in vitro

The self-ordering of C60 fullerene, doxorubicin and their mixture precipitated from aqueous solutions was investigated using atomic-force microscopy. The results suggest the complexation between the two compounds. The genotoxicity of doxorubicin in complex with C60 fullerene (C 60+Dox) was evaluated in vitro with comet assay using human lymphocytes. The obtained results show that the C60 fullerene prevents the toxic effect of Dox in normal cells and, thus, C60+Dox complex might be proposed for biomedical application.

On the origin of C₆₀ fullerene solubility in aqueous solution

In this work, we report that the surface hydroxylation of C60 molecules is the most likely mechanism for pristine C60 fullerenes/C60 fullerene aggregate stabilization in water, being independent of the method of C60 fullerene aqueous solution preparation.

Effect of fullerene C60 on ATPase activity and superprecipitation of skeletal muscle actomyosin

Creation of new biocompatible nanomaterials, which can exhibit the specific biological effects, is an important complex problem that requires the use of last accomplishments of biotechnology. The effect of pristine water-soluble fullerene C60 on ATPase activity and superprecipitation reaction of rabbit skeletal muscle natural actomyosin has been revealed, namely an increase of actomyosin superprecipitation and Mg2+, Ca(2+)- and K(+)-ATPase activity by fullerene was investigated. We conclude that this finding offers a real possibility for the regulation of contraction-relaxation of skeletal muscle with fullerene C60.

Water-soluble pristine fullerenes C60 increase the specific conductivity and capacity of lipid model membrane and form the channels in cellular plasma membrane

The aim of the present work was the investigation of the interaction of water-soluble pristine fullerenes C60 with bimolecular lipid model membrane (BLM) and cellular plasma membrane (PM). The findings demonstrate that the fullerenes C60 at low concentrations, namely in the concentration range of 1.0 x 10(-4) - 1.0 mg x ml(-1), are preferentially incorporated into the hydrophobic region of BLM, increasing, thus, its specific conductivity and specific capacity. Furthermore, upon interaction of fullerenes C60 with PM, pores or other type of local defects are formed, which are wide enough in order to permit the passage of water molecules across the cell membrane resulting to the externalization of phosphatidylserine from the inner to the outer PM leaflet.

Effect of iron-doped multi-walled carbon nanotubes on lipid model and cellular plasma membranes

The aim of the present work was the study of the interaction of multi-walled carbon nanotubes filled with iron (Fe-MWCNTs) with bimolecular lipid model membrane (BLM) and cellular plasma membrane (PM). The findings demonstrate that the Fe-MWCNTs adsorb on the BLM surface with possible partial build up in the hydrophobic area of fatty acid residues of lipids and increase its specific conductivity and capacity. Furthermore, upon interaction with the PM, the Fe-MWCNTs form channels which allow the flow of water to the cells and the externalization of phosphatidylserine from the inner to the outer PM leaflet.

Using C60 fullerenes for photodynamic inactivation of mosquito iridescent viruses

This article describes the photodynamic inactivation of mosquito iridescent virus (MIV) Aedes flavescens in the presence of water-soluble C(60) fullerenes. It has been observed that the photodynamic inactivation of MIV for about 1 h reduces the infectious titre of the virus in large wax-moth larvae Galleria mellonella to 4.5 lg ID(50)/mL. The influence of the C(60) concentration on its anti-viral activity was tested in the concentration range from 1 to 0.001 mg/mL. It has been found that C(60) is able to inactivate the iridovirus even in low concentrations. Consequently, the findings of this work suggest that photoexcited C(60) fullerenes can be successfully used for the inactivation of iridoviruses in biological systems.

Pristine C(60) fullerenes inhibit the rate of tumor growth and metastasis

AIM

To estimate the impact of C(60) fullerene aqueous solution (C(60)FAS) on the rate of transplanted malignant tumor growth and metastasis.

METHODS

Lewis lung carcinoma was transplanted into С57Bl/6J male mice. Conventional methods for the evaluation of antitumor and antimetastatic effects have been used.

RESULTS

The C(60)FAS at low single therapeutic dose of 5 mg/kg inhibited the growth of transplanted malignant tumor (antitumor effect) and metastasis (antimetastatic effect): the maximum therapeutic effect was found to be of 76.5% for the tumor growth inhibition; the increase of animal life span by 22% was found; the metastasis inhibition index was estimated as 48%.

CONCLUSION

It was found that water-soluble pristine С(60) fullerenes efficiently inhibit the transplanted malignant tumor growth and metastasis.

Using water-soluble C60 fullerenes in anticancer therapy

Growth experiments of transplanted malignant tumors in the presence of water-soluble C₆₀ fullerenes were performed on groups of mice. It was found that C₆₀ fullerenes efficiently inhibit the growth of transplanted malignant tumors. This behavior can be explained through their high antioxidant activity and the blocking of the specific cell receptors (for example, endothelial growth factor). The findings demonstrate the possibility of using C₆₀ fullerenes in anticancer therapy.

Low-temperature 1H-NMR spectroscopic study of doxorubicin influence on the hydrated properties of nanosilica modified by DNA

The effect of the anticancer drug--doxorubicin (Dox) on hydration properties of a nanocomposite material deposited on silica and modified by small amount of DNA (0.6 wt%) was studied by means of (1)H NMR spectroscopy at low temperatures (in the range of 200-280 K). Signals of either weakly (WAW) or strongly (SAW) associated water, as well as water associated with electrondonor groups of the composite surface (ASW), were observed. The findings reveal that, depending on the temperature and the composition of the dispersion medium, fast molecular exchange takes place between different forms of interphase water. The presence of Dox (0.1-0.2 wt%) in the dispersion medium leads to change of the relative concentrations of different forms of water.

Hyperthermic effect of multi-walled carbon nanotubes stimulated with near infrared irradiation for anticancer therapy: in vitro studies

It is proposed to use the novel paradigm of treating cancer with hyperthermic therapy using multi-walled carbon nanotubes (MWCNT) stimulated with near infrared (NIR) irradiation.

AIM

To establish the capacity of MWCNT stimulated with NIR irradiation to destroy Erlich ascitic carcinoma (EAC) cells.

MATERIALS AND METHODS

EAC cells suspension was irradiated with NIR heating lamp with a wavelength of 0.78-1.40 mm and power density of 3.5 W/cm2 over 1.5 min in the presence of MWCNT (0.1 mg/ml). The changes in the temperature of suspension with the NIR exposure time was measured using the differential cooper-constantan thermocouple. The viability of EAC cells was evaluated by trypan blue staining.

RESULTS

The death of 95.2% of EAC cells in the presence of MWCNT was observed after 1.5 min of NIR light irradiation: thermal ablation temperature was approximately 50 degrees C.

CONCLUSIONS

It was demonstrated that addition of MWCNT to EAC cell suspension results in the photo-ablative destruction of cells exposed to short time NIR irradiation.

Effect of the visible light irradiation of fullerene-containing composites on the ROS generation and the viability of tumor cells

AIM

To study the effect of fullerene-containing composites, irradiated by visible light, on the radical oxygen species (ROS) generation in thymocytes, ascitic cells from Erlich's tumor and leukemia cells L1210; to investigate viability of these cells in the presence of fullerene-containing composites under irradiation conditions.

MATERIALS AND METHODS

The viability of cells was evaluated by staining with 0.4% solution of the trypan blue; ROS were detected with the use of electron paramagnetic resonance (EPR) spectroscopy and spin traps; solutions of fullerene-containing composites were irradiated with mercury-vapor lamp.

RESULTS

We demonstrated that under irradiation conditions fullerene-containing composites increase the rate of ROS generation and decrease the number of viable tumor cells.

CONCLUSIONS

The obtained data allow to consider the fullerene-containing composites as potential agents for photodynamic therapy.

Design and evaluation of chemically synthesized siRNA targeting the NPM-ALK fusion site in anaplastic large cell lymphoma (ALCL)

The NPM-ALK fusion protein is found in up to 75% of pediatric anaplastic large cell lymphomas (ALCL). The ALK kinase becomes constitutively activated and triggers malignant transformation. Molecular targeting of the tumor-specific NPM-ALK fusion by gene-silencing methods seems to be a promising approach both for the treatment of ALCL and to decipher signaling pathways used by NPM-ALK. We designed and evaluated three chemically synthesized small interfering RNAs (siRNAs) for downregulation of the NPM-ALK fusion mRNA. Compared to HeLa cells transfected with the NPM-ALK expression plasmid only and to an siRNA containing two point mutations, the most potent anti-NPM-ALK siRNA reduced NPM-ALK protein expression in HeLa cells to almost undetectable levels, and the number of cells stained positively for NPM-ALK decreased by 80%. With respect to signaling, expressing of NPM-ALK increased the activity of AKT and ERK in HeLa cells, and this effect could be blocked by the specific siRNA targeting NPM-ALK. Expression of endogenous NPM-ALK mRNA in SR786 ALCL cells decreased by 50%-60% in cells transfected with the NPM-ALK siRNA. However, the amount of NPM-ALK protein was not influenced by a single transfection of the siRNAs against NPM-ALK. Repeated transfections over 8 days led to a significant reduction in NPM-ALK protein but without induction of apoptosis. We believe that the long protein half-life of NPM-ALK, at least 48 hours, limits the application of transiently transfected siRNAs. Nevertheless, RNA interference (RNAi) offers a suitable technique to dissect signaling pathways employed by NPM-ALK and may potentially be used to develop siRNA-based gene therapeutic approaches against NPM-ALK-positive lymphomas.

Rapidly fatal leishmaniasis in resistant C57BL/6 mice lacking TNF

The resolution of infections with the protozoan parasite Leishmania major in mice requires a Th1 response that is closely associated with the expression of IL-12, IFN-gamma, and inducible NO synthase. Previous Ab neutralization studies or the use of mice deficient for both TNF receptors suggested that TNF plays only a limited role in the control of parasite replication in vivo. In this study we demonstrate that resistant C57BL/6 (B6.WT) mice locally infected with L. major rapidly succumb to progressive visceral leishmaniasis after deletion of the TNF gene by homologous recombination. A reduction of the parasite inoculum to 3000 promastigotes did not prevent the fatal outcome of the disease. An influence of the altered morphology of secondary lymphoid organs in C57BL/6-TNF(-/-) (B6.TNF(-/-)) mice on the course of disease could be excluded by the generation of reciprocal bone marrow chimeras. Although infected B6.TNF(-/-) mice mounted an L. major-specific IFN-gamma response and expressed IL-12, the onset of the immune reaction was delayed. After in vitro stimulation, B6.TNF(-/-) inflammatory macrophages released 10-fold less NO in response to IFN-gamma than B6.WT cells. However, in the presence of a costimulus, e.g., L. major infection or LPS, the production of NO by B6.WT and B6.TNF(-/-) macrophages was comparable. In vivo, inducible NO synthase protein was readily detectable in skin lesions and draining lymph nodes of B6.TNF(-/-) mice, but its expression was more disperse and less focal in the absence of TNF. These are the first data to demonstrate that TNF is essential for the in vivo control of L. major.

Monocyte chemotactic protein-1 stimulates the killing of leishmania major by human monocytes, acts synergistically with IFN-gamma and is antagonized by IL-4

We recently demonstrated that monocyte chemotactic protein-1 (MCP-1) is strongly expressed in lesions of patients with self-healing localized cutaneous leishmaniasis (LCL) whereas it is scarce in those of chronic diffuse cutaneous leishmaniasis (DCL). This finding indicated that MCP-1 may contribute to the healing process. In the present study, we analyzed the capacity of MCP-1 to trigger leishmanicidal activities. The results show that MCP-1 directly stimulates the elimination of intracellular Leishmania parasites by human monocytes, a potential that correlates with the induction of reactive oxygen intermediates. Release of NO was not detected. To understand the cross-talk between the chemokine and T cell-associated cytokines, we studied the influence of the Th1 cytokine IFN-gamma and the Th2 cytokine IL-4 on MCP-1-mediated activation of human monocytes. The data demonstrate that IFN-gamma and MCP-1 synergistically activate monocytes to clear intracellular parasites, whereas IL-4 abrogates the effect of MCP-1. Furthermore, IL-4 inhibits MCP-1 expression by infected monocytes, a finding that may explain the lack of MCP-1 in chronic lesions. The data suggest a novel model for macrophage activation in cutaneous leishmaniasis. In lesions of LCL, the synergistic action of MCP-1 and IFN-gamma may stimulate the killing of parasites by macrophages and promote healing, whereas the presence of IL-4 in DCL lesions may favor the suppression of MCP-1 and, together with the lack of IFN-gamma, the progression of disease.

The chemokine repertoire of human dermal microvascular endothelial cells and its regulation by inflammatory cytokines

Activation of endothelium is a critical event during the initiation of inflammatory processes and is associated with the induction of cell adhesion molecules and cytokines. The latter include chemotactically active cytokines (chemokines) that promote leukocyte diapedesis from the circulation to sites of evolving inflammation. In this study we evaluated the chemokine repertoire of human endothelial cells derived from the skin (HDMECs) and regulation of these chemokines by cytokines. HDMECs and an immortalized human dermal microvascular endothelial cell line, HMEC-1, were investigated for the expression of C-X-C and C-C chemokines at mRNA and protein levels. Upon stimulation with interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), both HDMECs and HMEC-1 expressed high levels of IL-8, GRO, and monocyte chemoattractant protein-1 (MCP-1). RANTES was only weakly induced; however, concomitant treatment with TNF-alpha and interferon-gamma (IFN-gamma) led to upregulation of RANTES, indicating a synergy between these two cytokines. The C-X-C chemokine IFN-inducible protein-10 was upregulated by IFN-gamma but not by other cytokines studied. Macrophage inflammatory protein-1alpha and beta, 1-309, and ENA-78 could not be induced. The chemokine repertoires of HDMECs and HMEC-1 were compared to those of human umbilical vein endothelium and found to be rather similar with the important exception that IFN-gamma and IL-4 up-regulated MCP-1 only in macrovascular endothelium. Our data indicate that HDMECs contribute to the dermal cytokine network by selective production of MCP-1, IL-8, GRO, RANTES, and IP-10, which may critically influence the site-specific recruitment of leukocyte subsets.

Differential expression of GRO-alpha and IL-8 mRNA in psoriasis: a model for neutrophil migration and accumulation in vivo

Dense focal accumulation of neutrophils in the upper epidermis is a hallmark of psoriasis. Because the signals for neutrophil diapedesis and migration in vivo are not fully understood, psoriatic lesions with pronounced migration of neutrophils may serve as an important model for studying neutrophil chemotaxis. In this study, we present evidence for differential expression of the neutrophil chemotactic cytokines growth-related oncogene alpha, interleukin-8, and ENA-78 (epithelial cell derived and neutrophil-activating properties, 78 amino acids) in psoriatic lesions. In situ hybridization and immunohistochemistry of serial sections were employed to identify and microanatomically localize the cells producing these chemokines. High levels of focal interleukin-8 message were found to be expressed in the upper epidermis by keratinocytes and, most importantly, neutrophils themselves. Growth-related oncogene alpha transcripts were detected in clusters of keratinocytes of the upper epidermis at the same sites where interleukin-8 mRNA was abundant. In contrast to interleukin-8, growth-related oncogene alpha was also detected in the papillary dermis produced by vessel-associated cells. Sites of interleukin-8 and growth-related oncogene alpha mRNA expression were associated with infiltration of neutrophils. Interestingly, mRNA expression of the highly homologous chemokine ENA-78 was quiescent. In conclusion, our data indicate that growth-related oncogene alpha is an important chemoattractant for neutrophil diapedesis in vivo, whereas further migration of neutrophils and formation of micropustules appears to be influenced by the cooperative action of both growth-related oncogene alpha and interleukin-8.

Leishmania major infection in major histocompatibility complex class II-deficient mice: CD8+ T cells do not mediate a protective immune response

In order to evaluate the role of CD8+ T cells in cutaneous leishmaniasis, major histocompatibility complex (MHC) class II-deficient mice of C57BL/6 background lacking functional CD4+ T cells were infected with Leishmania major. In contrast to C57BL/6 wild-type mice which are resistant to infection with L. major, these mice developed severe skin lesions that did not heal. In comparison to susceptible BALB/c mice, however, lesion development in MHC class II-deficient mice was very much retarded, even though the increase in the parasite load in lymphoid organs was only slightly delayed. Lymph node cells from L. major-infected MHC class II-deficient mice produced very low levels of interferon-gamma upon stimulation with L. major antigen, whereas the response to the mitogen concanavalin A was not impaired. Interestingly, they did not release lymphokines associated with disease exacerbation (interleukin 4 and interleukin 10) either, suggesting that the delayed lesion development is caused by the lack of disease-promoting CD4+ cells rather than by the presence of protective CD8+ cells. The lack of L. major-reactive immunoglobulins in the serum of infected MHC class II-deficient mice indicates that B cells also cannot respond to parasite antigens in the absence of MHC class II-mediated helper signals. The data demonstrate that MHC class II-deficient mice are unable to restrict the spreading of L. major, although they contain highly increased proportions of CD8+ T cells. Thus, MHC class II-restricted immune responses, most likely mediated by functional CD4+ T cells, are essential for the control of primary infections with L. major.

Differential expression of chemokines in patients with localized and diffuse cutaneous American leishmaniasis

The abundance of macrophages in localized cutaneous leishmaniasis (LCL) and diffuse cutaneous leishmaniasis (DCL) lesions and differences in the composition of T cell subsets indicate involvement of cell-specific chemotaxis processes. The expression of macrophage chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1 alpha and -1 beta, RANTES (regulated on activation, normal T cell expressed and secreted), I-309, and interleukin-8 were investigated in lesions of patients with LCL or DCL. In LCL, high levels of MCP-1 and moderate levels of MIP-1 alpha were detected. In DCL, MCP-1 expression was significantly lower and MIP-1 alpha expression was predominant. All other chemokines investigated were minimally expressed or absent. These findings suggest that MCP-1 and MIP-alpha are responsible for the recruitment of macrophages and T cells in cutaneous leishmaniasis. The results show that self-healing LCL is associated with higher levels of MCP-1, which may stimulate macrophage microbicidal mechanisms, and nonhealing DCL is associated with higher levels of MIP-alpha.

Cutaneous leishmaniasis: a model for analysis of the immunoregulation by accessory cells

In the mammalian host, Leishmania are obligate intracellular parasites and invade macrophages and Langerhans cells. The accessory functions of both types of host cells are important for regulation of the specific cellular immune response and involve the following activities: infiltration into the site of infection, initiation of a T cell response, maintenance of immunity and the effector mechanisms that control intracellular parasite replication.

[The microbe colonization of the palatine tonsils of healthy school age children]

In 1988-1992 the tonsillar flora of 1799 children, six years of age and staying at certain kindergartens in Bavaria (Bayern), was examined. The microbiological investigations, directed at five indicator-germs showed the following results: 28.6% of the children were carriers of beta-haemolytic Streptococci, 17.4% of Enterobacteriaceae and 11.8% of Candida spp., Pseudomonadales and moulds could be found in 0.6% of the specimens.

[Simple in vitro test systems for determining the toxicity of environmental chemicals: microcultures of human lymphocytes and monoxenic ciliate cultures]

Two test methods were developed to assess (I) the cytotoxicity, (II) the environmental toxicity of chemicals. Test parameter for (I) is the growth inhibition of human T-lymphocytes stimulated by PHA (test period 6-7 days), for (II) the inhibition of cell multiplication of the ciliate Tetrahymena pyriformis grown monoxenically in a chemically defined medium which contained glucose and citrate as only carbon source (test period 13-14 days). The EC50 values (mol/l) of Pb, Cd, Hg, dichlorvos, atrazine and lindane were for (I): greater than or equal to 10(-2,5), 10(-5,4), 10(-5,6), 10(-5,0), 10(-4,75) and 10(-3,95) respectively, for (II): 10(-6,72), less than or equal to 10(-6,66), 10(-7,84), 10(-3,61), 10(-3,93) and 10(-4,75) respectively. The advantages of the described bioassays are simple handling and high sensitivity.