Induction and localization of Plasmodium falciparum stress proteins related to the heat shock protein 70 family

Induction of heat shock-related stress proteins Pfhsp and Pfgrp, similar in sequence to hsp70 (heat shock protein) and grp78 (glucose-regulated protein), respectively, was studied in culture-derived parasite Plasmodium falciparum. Elevation in temperature from 26 degrees C to 37 degrees C and higher caused significant induction of Pfhsp with a moderate effect on the synthesis of Pfgrp also. Synthesis of Pfgrp, however, was not induced by partial glucose deprivation. On the contrary, lack of glucose in the medium resulted in cessation of protein synthesis in the parasites. Other known inducers of grp synthesis in mammalian cells, i.e., calcium ionophore A23187 and inhibitors of glycosylation (tunicamycin, 2-deoxy glucose) were also without any apparent effect on the synthesis of Pfgrp. Heat shock-induced responses were transient in nature: removal of stress caused repression of these responses. The effect of glucose deprivation was only partially reversible with better recovery if parasites were subjected to glucose starvation at 26 degrees C than at 37 degrees C. Northern blot analysis and in vitro translation of mRNA revealed a parallel increase in the levels of mRNA for Pfhsp upon heat shock. Immuno-gold electron microscopy with cultured parasites revealed nuclear location of Pfhsp and primarily cytoplasmic (probably endoplasmic reticulum) location of Pfgrp. These findings suggest that SDEL (carboxy terminal sequence of Pfgrp) might play a similar role in the cellular localization of Pfgrp as does the sequence KDEL in mammalian cells and HDEL in yeast.

Pentoxifylline does not attenuate acute lung injury in the absence of granulocytes

Pentoxifylline (PTX), a methylxanthine, can suppress polymorphonuclear leukocyte (PMN) activation and attenuate sepsis-induced acute lung injury. We investigated whether PTX prevents non-PMN-dependent lung injury. First we studied four groups of granulocyte-depleted guinea pigs (control, PTX, Escherichia coli, and E. coli + PTX). Lung injury was assessed by wet-to-dry lung weight (W/D) ratio and lung tissue-to-plasma 125I-albumin ratio (albumin index, AI). The E. coli group showed a significant increase in the lung W/D ratio and AI compared with the control and PTX groups. However, PTX did not prevent the E. coli-induced increase in the lung W/D ratio and AI. Next we investigated the effects of PTX on endothelial cell monolayer permeability and adenosine 3',5'-cyclic monophosphate (cAMP) levels. Whereas E. coli lipopolysaccharide (LPS) alone increased the endothelial permeability, PMNs added to the endothelial monolayers and exposed to LPS enhanced the increase. PTX attenuated the permeability increase mediated by LPS-exposed PMNs. PTX did not prevent the LPS-induced increase in permeability when PMNs were not present, although PTX increased endothelial cell cAMP levels. These data demonstrate that 1) PTX does not prevent lung injury in granulocyte-depleted guinea pigs; 2) PTX does not prevent LPS-induced increases in endothelial cell permeability, despite increased cAMP levels; and 3) PTX attenuates PMN-dependent increases in endothelial cell permeability.

[Glycosaminoglycans associate with corneal transparency]

Keratoplasty specimens form 12 patients with macular corneal dystrophy, 1 patient with systemic glycosaminoglycan stored disease and 12 cases of normal cornea were studied by electron-histochemistry. The results showed that the normal cornea contains chondroitin sulfate in the basement membrane and bowman's membrane, Keratan sulfate and chondroitin sulfate between the collagen fibrils of strome, heparan sulfate on the cell membranes of various cells, and hyaluronic acid on the surface of endothelial cell. The chondroitin sulfate of the stroma of macular corneal dystrophy increases, but the keratan sulfate is absent. The keratocytes and endothelial cells of macular corneal dystrophy synthesize fibrillogranular material and abnormal glycosaminoglycan. The heparan sulfate is stored in the cytoplasm of corneal epithelial cell and keratocyte of systemic glycosaminoglycan stored disease and absent on the membrane of involved cells. The authors suggest that glycosaminoglycan play important role in maintaining corneal transparency and the changes of distribution, character and quantity of glycosaminoglycan in the cornea cause corneal opaqueness.

Attenuation of LPS-induced neutrophil thromboxane b2 release and chemiluminescence

Polymorphonuclear leukocytes (PMN) may play a key role in acute lung injury and ARDS. The mechanisms of PMN-mediated lung injury include the release of inflammatory mediators, such as oxygen free radicals which cause direct tissue injury, and arachidonic acid metabolites which cause pulmonary vasoconstriction and increased vascular permeability. The goals of this in vitro study were 1) to assess the effects of PMN-activating agents (lipopolysaccharide, LPS; phorbol myristate acetate, PMA; tumor necrosis factor, TNF) on PMN thromboxane B2 (TXB2) release and oxygen free radical production and 2) to determine the effects of agents purported to suppress PMN activity (pentoxifylline, PTX; adenosine; dibutyryl cyclic AMP, DBcAMP; and terbutaline, TBN) on activator-induced PMN TXB2 release and oxygen free radical production. PMN TXB2 release was determined by radioimmunoassay and oxygen free radical production was monitored by chemiluminescence. Our results show that 1) LPS and PMA significantly increase PMN TXB2 release, whereas tumor necrosis factor (TNF) has no effect; 2) LPS and PMA significantly increase PMN chemiluminescence; 3) DBcAMP and TBN significantly reduce LPS-induced PMN TXB2 release whereas PTX and adenosine do not; 4) TBN significantly reduces PMA-induced PMN TXB2 release whereas other agents do not; 5) All agents (PTX, adenosine, DBcAMP, and TBN) significantly reduce LPS-induced PMN chemiluminescence but none attenuate PMA-induced PMN chemiluminescence. We conclude that: LPS and PMA activate PMN manifested by TXB2 release and chemiluminescence. Additionally, all the PMN suppressing agents do attenuate some PMN functions. Of interest, PTX, adenosine, DBcAMP, and TBN have different effects depending upon functional assay and activating agent. It will be important to investigate the mechanisms by which PMN suppressing agents alter signal transduction resulting in differential effects on PMN function.

Early post-treatment with pentoxifylline or dibutyryl cAMP attenuates Escherichia coli-induced acute lung injury in guinea pigs

We examined effects of early post-treatment with the methylxanthine pentoxifylline (PTXF), or the cell-permeable adenosine 3', 5'-cyclic monophosphate (cAMP) analog dibutyryl cAMP (db-cAMP) on Escherichia-coli-induced acute lung injury in guinea pigs. Acute lung injury was assessed by measurements of lung water (lung wet/dry weight ratio; W/D ratio), the concentration ratio of 125I-albumin in bronchoalveolar lavage (BAL) fluid and lung tissue compared with plasma (albumin index; BAL-AI or tissue-AI), and total differential leukocyte count in BAL fluid. Mean arterial pressure (Pa) and peripheral WBC counts were monitored continuously over the 8-h experiment. Septicemia was induced by a bolus injection of 2 x 10(9)/kg live E. coli. Thirty minutes later the animals received a bolus injection followed by continuous infusion of PTXF (20 mg/kg + 20 mg/kg/h; n = 8) or db-cAMP (2 mg/kg + 2 mg/kg/h; n = 8) or saline (septic control; n = 8). Nonseptic control groups were also studied. The lung W/D ratio, BAL-AI, lung tissue-AI, and BAL leukocyte count increased significantly in the septic control group. The PTXF-septic and db-cAMP-septic groups showed no significant increase in lung W/D ratio, BAL-AI, and lung tissue-AI. However, there was no difference in BAL total and differential leukocyte count as compared with the septic control group. PTXF and db-cAMP had no effect on E. coli-induced changes in peripheral WBC count and Pa. Comparison in vitro experiments demonstrated that PTXF and db-cAMP inhibited the endotoxin-induced (E. coli) chemiluminescent response of isolated guinea-pig polymorphonuclear leukocytes (PMN).(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of tumor necrosis factor-induced endothelial cell cytotoxicity and neutrophil chemiluminescence

Our laboratory has previously shown that the administration of tumor necrosis factor (TNF), a cytokine produced by activated mononuclear cells, to guinea pigs produces a syndrome similar to gram-negative sepsis or ARDS. Pentoxifylline (PTX), a methylxanthine, protects against TNF-induced and sepsis-induced acute lung injury in vivo. We now report on in vitro cellular studies of PMN-mediated cellular injury and its attenuation. We studied TNF-induced bovine pulmonary artery endothelial cell (EC) cytotoxicity both with and without PMN. A 51Cr release assay was used to measure EC damage. Further, we investigated PMN function in response to TNF by measuring chemiluminescence. Agents that attenuate EC damage and PMN activation were evaluated in the above assays. Results revealed that TNF causes EC injury (p less than 0.05) and PMN increase TNF-induced EC injury. Furthermore, PTX, aminophylline (AMPH), caffeine, and forskolin attenuate TNF-induced EC cytotoxicity only in the presence of PMN (p less than 0.05). Of interest, dibutyryl cAMP (DBcAMP) protects EC from TNF-induced injury both with and without PMN. Agents that may increase cAMP levels in PMN (PTX, DBcAMP, forskolin, isobutyl methylxanthine, and terbutaline) significantly attenuate TNF-induced PMN chemiluminescence (p less than 0.05). We conclude that TNF causes EC damage and PMN increase this damage. Furthermore, PTX, AMPH, caffeine, and forskolin can attenuate TNF-induced EC injury in the presence of PMN, whereas DBcAMP attenuates TNF-induced EC injury with and without PMN. In addition, agents that may increase intracellular cAMP levels in PMN can attenuate TNF-induced PMN chemiluminescence. Thus, these agents likely attenuate TNF-induced PMN-mediated EC injury through their inhibitory effects on PMN.

Human immune response directed against Plasmodium falciparum heat shock-related proteins

Heat shock-related stress proteins present in all eucaryotes and procaryotes have been shown to be immune targets in a broad range of infections. We have analyzed sera from people exposed primarily to Plasmodium falciparum for specific antibodies against two heat shock-related proteins (proteins similar to the heat shock protein with a molecular weight of 75,000 [Pfhsp] and a glucose-regulated protein with a molecular weight of 72,000 [Pfgrp]). In an immunoprecipitation analysis with metabolically labeled parasites and synthetic peptides in an enzyme-linked immunosorbent assay, specific antibodies against Pfhsp and Pfgrp were detected in the sera of these individuals. Sera from people exposed to a different human malarial parasite, Plasmodium vivax, did not react with the peptides in an enzyme-linked immunosorbent assay. Southern blot analysis with DNA isolated from P. falciparum from different geographical locations showed a conservation of genes for these stress proteins; thus, they are likely to be immune targets in various endemic areas. Lymphocytes from two tested immune donors responded in proliferation assays to purified Pfhsp and Pfgrp and purified recombinant proteins. However, a similar response was also seen in lymphocytes from nonimmune individuals and has raised questions pertaining to a generalized responsiveness of lymphocytes to some common determinants present in heat shock-related proteins in various pathogens.

Gene targeting in normal and amplified cell lines

Targeted recombination in mammalian cells is rare compared with non-homologous integration. In Saccharomyces cerevisiae the reverse is true. Differences in targeting efficiency could arise because a target of unique DNA is 200 times more dilute in mammalian genomes than it is in yeast. We tested this possibility by measuring gene targeting in normal CHO cells with two copies of the dihydrofolate reductase (DHFR) gene and in amplified CHOC 400 cells, which carry 800 copies. If the concentration of the target gene is critical, amplified cells should show an enhanced frequency of targeted recombination relative to non-homologous integration. Using a positive/negative selection protocol, we demonstrated that the efficiency of targeting into DHFR genes is indistinguishable in normal and amplified CHO cells. As targeting does not depend on the number of targets, the search for homology is not a rate-limiting step in the mammalian pathway of gene targeting. Thus, the difference in genome size is not the basis for the different outcomes of targeting experiments in S. cerevisiae and mammals.

[Studies of the herbal and botanical origins of seman Cuscutae]

Herbalogical study shows that Seman Cuscutae originated from Cuscuta chinensis is one of the most commonly used drugs in ancient times. Survey of botanical origins indicates that there are 9 species in Genus Cuscutae and 4 of them are commodities. The Cuscuta chinensis specified in current Chinese Pharmacopoeia (1985) is not the principal one.

Allogeneic bone marrow transplantation for the treatment of leukemia

Eighteen patients with leukemia have received HLA-identical allogeneic bone marrow transplantation (BMT) at our hospital since 1981. Fifteen of these patients have been living without relapse. for prophylaxis of GVHD, MTX was used in 8 patients, and cyclosporine (CSP) together with MTX in 6 patients, 3 received multiple agents at much smaller dosage, including monoclonal antibody. All patients received intravenous placental gamma-globulin, and 16 received garlic extract. Three patients died. One, who neither received MTX, nor CSP died of hyperacute GVHD, one who did not receive garlic extract died of GMV pneumonia, and the third one died of tuberculosis 18 months after BMT.

Stage-specific gametocytocidal effect in vitro of the antimalaria drug qinghaosu on Plasmodium falciparum

Qinghaosu, an anti-malaria drug, has been found to kill not only asexual blood stages but also the early stages of gametocytes of Plasmodium falciparum. The effect of qinghaosu in vitro depends on the concentration of the drug as well as on the initial parasitemia level (IC50 = 10-20 nM with 1% initial parasitemia). Resistance of P. falciparum to other anti-malaria drugs, e.g., chloroquine and pyrimethamine, did not affect susceptibility of its asexual and sexual stages to qinghaosu. Gametocytocidal effect of qinghaosu may play a role in the interruption of malaria transmission.

Prevention of interleukin 2-induced acute lung injury in guinea pigs by pentoxifylline

We administered recombinant human interleukin 2 (IL-2) to guinea pigs to investigate whether IL-2 would cause acute lung injury. In addition, we examined the effects of pentoxifylline (PTXF) on IL-2-induced acute lung injury. Three groups of animals were studied over a period of 8 h. The saline control group was injected intravenously with 2 ml of pyrogen-free saline; the IL-2 group was injected intravenously with 4 X 10(6) U/kg recombinant IL-2; and the IL-2-PTXF group was injected with a 20-mg/kg bolus of PTXF followed by a continuous infusion (6 mg.kg-1.h-1) started 60 min before injection of 4 X 10(6) U/kg IL-2. Lung water (wet-to-dry lung weight ratio), the concentration ratios of 125I-albumin in bronchoalveolar lavage (BAL) fluid and lung tissue compared with plasma (125I-albumin BAL-to-plasma, 125I-albumin lung-to-plasma), and cell counts in BAL fluid were examined. An intravenous injection of IL-2 caused an increased lung water (P less than 0.01), an increased 125I-albumin lung-to-plasma ratio (P less than 0.05), and a significant increase in the absolute number of neutrophils, lymphocytes, and macrophages in BAL fluid compared with the saline control. In contrast, the PTXF-pretreated group did not demonstrate IL-2-induced acute lung injury (lung water, 125I-albumin lung-to-plasma) or increased accumulation of neutrophils, lymphocytes, and macrophages in the BAL. These data suggest a possible role for PTXF in attenuating the side effects of IL-2.

Effects of tumor necrosis factor on PMN chemotaxis, chemiluminescence, and elastase activity

Tumor necrosis factor (TNF) has been proposed as an important mediator of the inflammatory response in acute lung injury. To better understand polymorphonuclear leukocyte (PMN) activation during acute lung injury, we evaluated the effects of TNF on several in vitro PMN functions, including chemotaxis, chemiluminescence, and elastase activity. In the chemotaxis assay using a modified Boyden chamber, TNF alone or with N-formyl-methionyl-leucyl-phenylalanine (FMLP, 10(-8) mol/L) did not alter PMN migration. TNF suspended with 1% zymosan-activated serum (ZAS) increased PMN migration at low concentrations and decreased migration at high concentrations (control 99 +/- 4.8 microns, n = 9; TNF 0.1 ng/ml 135 +/- 9.4 microns, n = 5, p less than 0.01; TNF 1000 ng/ml 62 +/- 7.5 microns, n = 5, p less than 0.01). In the chemiluminescence assay, TNF (1000 ng/ml) induced a 3-fold increase in the PMN chemiluminescent response. However, TNF incubated with PMN did not cause an increase in supernatant elastase activity. These data reveal TNF induced the production of PMN reactive oxygen species as evidenced by an increased chemiluminescent response. Whereas TNF increased chemotaxis at low concentrations in the presence of 1% ZAS, high concentrations of TNF similar to levels detected in septic shock caused a decrease in chemotaxis that might contribute to retaining PMN in sites of inflammation. It is thus suggested that TNF may contribute to inflammation by stimulating the production of PMN-reactive oxygen species and modulating-PMN chemotaxis.

The effects of aminophylline and pentoxifylline on multiple organ damage after Escherichia coli sepsis

We studied the effects of the methylxanthines, aminophylline (AMPH) and pentoxifylline (PTXF), on multiple organ damage following Escherichia coli sepsis in guinea pigs. To assess multiple organ damage, 125I-labeled albumin accumulation was measured in bronchoalveolar lavage (BAL) fluid, lung, kidneys, liver, heart, adrenal glands, and spleen and expressed as a ratio of BAL fluid or tissue to 125I-labeled albumin plasma (albumin index: Al). Wet-to-dry lung weight (W/D) ratios were also measured. The methylxanthines were administered by a bolus injection followed by a continuous infusion. The seven experimental groups included: saline-control, AMPH-control, PTXF-control, E. coli septic-control, E. coli septic-AMPH high dose, E coli septic-AMPH low dose, and E. coli septic-PTXF. The AI of the BAL fluid and all examined organs significantly increased in the septic-control group compared to those in the saline-, AMPH-, and PTXF-control groups, In all septic-methylxanthine groups, the AI of the BAL fluid and all organs, except for the spleen, were significantly lower than those of the septic-control group. Compared to the saline-, AMPH-, and PTXF-control groups, the septic-control group revealed a significant increase in lung W/D ratios, whereas the septic-AMPH high and low dose groups and the septic-PTXF group did not. Of importance, the septic-PTXF group did not cause a significant decrease in mean arterial pressure (MAP) as compared to the control groups, whereas the septic-AMPH groups did cause a significant decrease in MAP compared to the septic-control group. Therefore, the data from this experiment demonstrate that both AMPH and PTXF attenuate the multiple organ albumin leak seen in septic guinea pigs. However, PTXF exerted this protective effect with no discernible effect on the MAP whereas the MAP of AMPH-treated guinea pigs was significantly decreased.

Primary cells and established cell lines join DNA ends with the same efficiency relative to homologous recombination

The joining of DNA ends was compared in the established CV1 cell line and in African green monkey kidney primary cells, from which the CV1 cell line was established. Using a linear SV40 genome that carries a terminal repeat of 526 nucleotide pairs, we measured the efficiency of circularization by end joining relative to circularization by homologous recombination between the terminal repeats. The ratios of end joining to homologous recombination were identical in the two types of cells regardless of whether the DNA ends were sticky, blunt, or mismatched. These studies demonstrate that the efficient end joining observed in established cell lines is not a peculiar adaptation to life in culture, but rather reflects a normal aspect of DNA metabolism in mammalian cells. Furthermore, the similar results in primary and established cells support the general validity of using data from studies of cultured cells to formulate models of recombinational processes in primary cells and potentially in multicellular organisms as well.

Specific inhibition of cell-surface T-cell receptor expression by antisense oligodeoxynucleotides and its effect on the production of an antigen-specific regulatory T-cell factor

We have used antisense oligodeoxynucleotides corresponding to genes encoding the variable (V) region of the T-cell receptor (TCR) alpha and beta chains (V alpha and V beta) to control TCR expression in T-cell hybridomas. Two hybridomas, A1.1 and B1.1, recognize a synthetic polypeptide antigen designated poly 18 (poly[Glu-Tyr-Lys-(Glu-Tyr-Ala)5]) together with I-Ad. We have found that TCR function (production of lymphokines in response to antigen) and T3 expression were removed after protease treatment of the cells and were fully recovered 48 hr later. However, when antisense oligodeoxynucleotides corresponding to the appropriate TCR V genes were present after protease treatment, little or no recovery of TCR function or T3 expression was observed. This effect was specific for the TCR V genes utilized by the T cell: antisense oligodeoxynucleotides corresponding to the TCR V regions of A1.1 had no effect on TCR expression in B1.1 and vice versa. Thus, antisense oligodeoxynucleotides can be used to temporarily block expression of a TCR gene in a T-cell hybridoma. This technique was then applied to a paradoxical phenomenon in A1.1 cells. We had observed previously that A1.1 releases an antigen-specific immunoregulatory activity that shows the same antigenic fine specificity as is displayed by the TCR of A1.1. We now report that antisense oligodeoxynucleotides corresponding to the A1.1 V alpha gene blocked the production of this soluble antigen-specific activity by the cell. Antisense oligodeoxynucleotides corresponding to A1.1 V beta, on the other hand, had no effect on the production of this antigen-specific activity. We discuss these observations in the context of recent findings on the nature of T cell-derived antigen-specific regulatory factors.

An antigen-specific helper T cell hybridoma produces an antigen-specific suppressor inducer molecule with identical antigenic fine specificity. Implications for the antigen recognition and function of helper and suppressor inducer T cells

We have previously described a T cell hybridoma, A.1.1, that responds to specific Ag (P18, a synthetic polypeptide of defined sequence) in the context of I-Ad by producing lymphokines. Herein we report that this cell also releases, into culture supernatants and ascites fluid, an Ag-specific activity that functions in the induction of suppression of anti-SRBC PFC responses. This suppressive activity requires a) Ag-non-specific accessory molecules from a T suppressor inducer factor, b) Ly-2+ T cells in the assay cultures, and c) the specific Ag (P18) conjugated to the SRBC in the assay cultures. The specificity of the A.1.1-derived activity was demonstrated by the absence of suppression in cultures containing SRBC, BSA-SRBC, or conalbumin-SRBC rather than P18-SRBC. Further, the A.1.1-derived activity bound to, and could be eluted from, P18 but not conalbumin. Using a panel of synthetic variant peptides, we have mapped the critical residues in P18 required for Ag/I-Ad induced activation of A.1.1. These peptides were tested for their ability to act as targets for the A.1.1-derived suppressive activity when conjugated to SRBC and added to assay cultures. All peptides capable of stimulating the A.1.1 T cells to release lymphokines were similarly effective in the suppressor assay. Thus, the recognition of Ag by the T cells and by the T cell-derived activity appeared to be identical. The A.1.1-derived molecule was found to be capable of inducing L3T4- T cells to act as suppressor T cells following culture. These suppressor cells were active in inhibiting anti-SRBC responses in the absence of P18 and bore the Ly-2 surface marker. Thus, it is likely that the function of this Ag-specific molecule is to induce Ly-2+ suppressor T cells and thereby cause the inhibition of the response. This function is distinct from that normally associated with helper T cells and may shed new light on the possible relationship between the cell surface T cell receptor for Ag and Ag-specific T suppressor inducer molecules.