1,25-Dihydroxyvitamin D3 upregulates functional CXCR4 human immunodeficiency virus type 1 coreceptors in U937 minus clones: NF-kappaB-independent enhancement of viral replication

U937 cell clones which sustain efficient or poor replication of human immunodeficiency virus type 1 (HIV-1) (referred to herein as plus clones and minus clones, respectively) have been previously described. 1,25-Dihydroxyvitamin D3 (vitamin D3) potently induced HIV-1 replication and proviral DNA accumulation in minus clones but not in plus clones. Vitamin D3 did not induce NF-kappaB activation but selectively upregulated CXCR4 expression in minus clones. The CXCR4 ligand stromal-cell derived factor-1 induced Ca2+ fluxes and inhibited both constitutive and vitamin D3-enhanced HIV replication in minus clones.

Evaluation of trickle bed air biofilter performance as a function of inlet VOC concentration and loading, and biomass control

The 1990 Amendments to the Clear Air Act have stimulated strong interest in the use of biofiltration for the economical, engineered control of volatile organic compounds (VOCs) in effluent air streams. Trickle bed air biofilters (TBABs) are especially applicable for treating VOCs at high loadings. For long-term stable operation of highly loaded TBABs, removal of excess accumulated biomass is essential. Our previous research demonstrated that suitable biomass control for TBABs was achievable by periodic backwashing of the biofilter medium. Backwashing was performed by fluidizing the pelletized biological attachment medium with warm water to about a 40% bed expansion. This paper presents an evaluation of the impact of backwashing on the performance of four such TBABs highly loaded with toluene. The inlet VOC concentrations studied were 250 and 500 ppmv toluene, and the loadings were 4.1 and 6.2 kg COD/m3 day (55 and 83 g toluene/m3 hr). Loading is defined as kg of chemical oxygen demand per cubic meter of medium per day. Performance deterioration at the higher loading was apparently due to a reduction of the specific surface of the attached biofilm resulting from the accumulation of excess biomass. For a toluene loading of 4.1 kg COD/m3 day, it was demonstrated that the long-term performance of biofilters with either inlet concentration could be maintained at over 99.9% VOC removal by employing a backwashing strategy consisting of a frequency of every other day and a duration of 1 hr.

Interleukin 10 increases CCR5 expression and HIV infection in human monocytes

The immunosuppressive and antiinflammatory cytokine interleukin (IL) 10 selectively upregulates the expression of the CC chemokine receptors CCR5, 2, and 1 in human monocytes by prolonging their mRNA half-life. IL-10-stimulated monocytes display an increased number of cell surface receptors for, and better chemotactic responsiveness to, relevant agonists than do control cells. In addition, IL-10-stimulated monocytes are more efficiently infected by HIV BaL. This effect was associated to the enhancement of viral entry through CCR5. These data add support to an emerging paradigm in which pro- and antiinflammatory molecules exert reciprocal and opposing influence on chemokine agonist production and receptor expression.

Control of toxic metal emissions from combustors using sorbents: a review

This paper constitutes a review of the control of toxic metal emissions using sorbents. The objective of sorbent-injection methods is to effectively capture the metal species (preferably transform it to an environmentally benign form) and to suppress the fraction in the submicrometer mode. The design of an effective sorbent-injection methodology thus requires an understanding of the fate of the metallic species and its transformation pathways (transfer to the gas phase, subsequent chemistry at high temperatures, and aerosol formation and growth dynamics) in the combustor. Several different sorbent methodologies used for metals capture are discussed, and a mechanistic description is provided. The need for further experimentation and pilot scale testing is also emphasized.

Interleukin-6 induces monocyte chemotactic protein-1 in peripheral blood mononuclear cells and in the U937 cell line

Induction of chemokine gene expression from peripheral blood mononuclear cells (PBMCs) stimulated by proinflammatory cytokines plays an important role in both wound repair and response to infectious agents. In the present study, we show that the proinflammatory cytokine interleukin-6 (IL-6) potently induced mRNA expression and secretion of the CC chemokine monocyte chemotactic protein 1 (MCP-1) in PBMCs. In addition, because human immunodeficiency virus (HIV) infection in vivo and in vitro has been shown to dysregulate the production of and/or the response to cytokines, PBMCs from both healthy uninfected and HIV-infected individuals were studied for their constitutive and IL-6-induced expression of MCP-1. No substantial differences were observed between the two groups of individuals. In addition, IL-6 upregulated MCP-1 expression in the promonocytic cell line U937 and in its chronically HIV-infected counterpart, U1. In these cell lines, IL-6 selectively induced MCP-1 and not other chemokines, including regulated upon activation normal T cells expressed and secreted (RANTES), macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and IL-8. IL-6 induction of MCP-1 was partially inhibited by hydrocortisone in U1 cells. Thus, IL-6 activates PBMCs to secrete MCP-1, a CC chemokine pivotal for monocyte recruitment in tissue and organs in which important inflammatory events occur.

Primary pulmonary hypertension in non-cirrhotic portal fibrosis

BACKGROUND

Primary pulmonary hypertension (PPH) has been reported in association with cirrhosis and extrahepatic portal venous obstruction; reports of PPH in noncirrhotic portal fibrosis (NCPF) are few.

AIM

To evaluate pulmonary arterial pressure in patients with NCPF.

METHODS

Twenty two patients with NCPF underwent hemodynamic studies for pulmonary arterial pressure after excluding secondary causes of pulmonary hypertension. Hemodynamic studies were carried out through the femoral route using 7F Swan-Ganz catheter. Splenoportal venography was done by percutaneous splenic puncture.

RESULTS

The mean pulmonary arterial pressure was 12.9 +/- 3.1 mmHg with pulmonary capillary wedge pressure of 8.3 +/- 2.1 mmHg in 20 of 22 cases; in the remaining two cases, the corresponding pressures were 30 mmHg and 28 mmHg and 13 mmHg and 12 mmHg, respectively.

CONCLUSION

Two of 22 patients with NCPF had PPH. PPH can thus develop without hepatocellular failure or recurrent embolization from portal axis thrombosis as has been described in cirrhosis.

Role of pro-inflammatory cytokines and beta-chemokines in controlling HIV replication

Several members of the cytokine network play an important role in controlling the replication of the human immunodeficiency virus (HIV) in several experimental systems. Their effects can be categorized in the following three functional groups: (1) HIV-inductive cytokines; (2) HIV-suppressive cytokines; (3) cytokines with both activating and inhibiting capacities. Studies on the mechanism of action of these molecules have highlighted the fact that several steps of the retrovirus life cycle, from binding to budding of progeny virions from the infected cell, are affected by cytokines. This general concept has been recently substantiated by the discovery that certain beta-chemokines can act as blockers of viral entry by interfering with HIV co-receptors. Finally, it is important to recognize that cytokines have gone beyond their role as potential pathogenetic or protective endogenous cofactors in HIV replication and disease progression, and are becoming experimental therapeutic agents for HIV disease, best illustrated thus far by the case of interleukin-2.

Understanding utero-placental blood flow in normal and hypertensive pregnancy through a mathematical model

Normal development of utero-placental circulation is crucial not only for the survival and growth of the fetus in utero, but also for maternal well-being. Any disturbance or abnormality may reflect underlying pathology. Geometric conversion of a pre-pregnant spiral vessel into a divergent low-resistance vessel is believed to be responsible for the increased utero-placental blood flow in normal pregnancy. Known biomedical investigative techniques have failed to explain many such underlying haemodynamic changes taking place in the utero-placental system. Therefore, proper understanding of the system using a mathematical model has been found to be useful. The physiological fluid dynamic study is the first in this branch of physiology. Abnormal pressure gradient, axial velocity, volume flow and shear rate are obtained for various slowly changing geometries such as, tapering, divergence, local constrictions and sinusoidal tube for low Womersley parameters. The model can explain many enhanced patho-physiological changes, such as persistence or the appearance of local constriction in the utero-placental vessels. Such pathological changes are considered to be responsible for very high utero-placental resistance, leading to blood flow insufficiency in pre-eclampsia or intra-uterine growth retardations. It is believed that these changes may be caused by low shear rate on the pre-existing deranged or abnormal endothelium. Furthermore, this derangement is caused by an abnormal proliferation of either spiral vessels or the invading non-villous trophoblasts. Doppler flow study can explain and validate some of the theoretically derived flow velocity results. The study opens up a new area of research into utero-placental physiological fluid dynamics.

Linkage of blepharophimosis syndrome in a large Indian pedigree to chromosome 7p

Blepharophimosis syndrome (BPES) is an autosomal dominant disorder involving abnormal eyelid development. Cytogenetic and linkage analyses have previously implicated the chromosome 3q23 region in multiple cases of this syndrome. However, in a few cases cytogenetic analyses have implicated other chromosomal regions in this condition. Here we report linkage of BPES in a large Indian pedigree to chromosome 7p13-p21; affected only two-point and multipoint analyses using D7S488, D7S2551 and D7S2562 both showed peak lod scores of 3.61 coincident with D7S2562. Recombinations in affected individuals placed the critical region between D7S488 and D7S629. When both affected and unaffected individuals were considered, a maximum two-point lod score of 3.38 at theta = 0.08 was obtained with D7S2551 while a peak multipoint lod score of 3.64 was obtained between D7S488 and D7S2551. Segregation analysis revealed two unaffected individuals carrying the affected haplotype accounted for the difference in peak, relative to the affected only analysis. The chromosome 7p candidate genes inhibin beta A and epidermal growth factor receptor map outside this region whereas the HOX1 gene cluster may map inside this region. Although BPES is sometimes associated with female infertility due to premature ovarian failure, in the current family affected females were fertile. The current finding together with the previous evidence implicating chromosome 3q2 provides strong evidence that BPES involves locus heterogeneity; this point should be considered when counselling affected families.

PKC alpha regulates thrombin-induced PDGF-B chain gene expression in mesangial cells

Thrombin is a potent mitogen for mesangial cells and stimulates PDGF B-chain gene expression in these cells. It also activates phospholipase C (PLC) resulting in an increase in cytosolic Ca2+ and diacylglycerol (DAG) that are the physiological activators of protein kinase C (PKC). Immunoprecipitation of specific PKC isotypes from thrombin-stimulated mesangial cells with subsequent measurement of their enzymatic activity shows activation of Ca(2+)-dependent PKC alpha and Ca(2+)-independent PKC zeta in a time dependent manner. Optimum activation of both of these isozymes was obtained at 60 minutes. PKC alpha activity increased 83% over basal while activity of PKC zeta increased 104%. Prolonged exposure of mesangial cells to phorbol myristate acetic acid (PMA) inhibited the enzymatic activity of PKC alpha but not PKC zeta. This inhibition of PKC alpha had no effect on thrombin-induced DNA synthesis but abolished PDGF B-chain gene expression induced by thrombin. These data provide the first evidence that PKC alpha activation is necessary for thrombin-induced PDGF B-chain gene expression but not for thrombin-induced DNA synthesis.

Cross-linking of CD30 induces HIV expression in chronically infected T cells

CD30, a member of the tumor necrosis factor (TNF) receptor family, is expressed constitutively on the surface of the human T cell line ACH-2, which is chronically infected with human immunodeficiency virus type-1 (HIV)-1. We demonstrate that cross-linking CD30 with an anti-CD30-specific monoclonal antibody, which mimics the described biological activities of the CD30 ligand (CD30L), results in HIV expression. CD30 cross-linking does not alter proliferation of ACH-2 cells and the induction of HIV expression is not mediated by endogenous TNF alpha/beta. Furthermore, cross-linking of CD30 leads to NF-kappa B activation and enhanced HIV transcription. Thus, CD30-CD30L interactions mediate the induction of HIV expression by a kappa B-dependent pathway that is independent of TNF. This mechanism may be important in the activation of HIV expression from latently infected CD4+ T cells, especially in lymphoid organs where cell to cell contact is conducive to receptor-ligand interactions.

Effect of cellular differentiation on cytokine-induced expression of human immunodeficiency virus in chronically infected promonocytic cells: dissociation of cellular differentiation and viral expression

Cellular differentiation is thought to play an important role in the susceptibility of monocytic lineage cells to human immunodeficiency virus (HIV) infection as well as in their ability to support virus replication. In addition, virus replication in monocytes/macrophages has been demonstrated in vitro to be strongly modulated by several cytokines such as tumor necrosis factor alpha and granulocyte-macrophage colony-stimulating factor. The purpose of the present study was to investigate the interaction between cellular differentiation and cytokines in the regulation of HIV expression from chronically infected monocytic lineage cells. U1, a persistently HIV-infected promonocytic cell line, is characterized by low levels of virus expression which can be modulated by several cytokines. 1 alpha,-25-Dihydroxyvitamin D3 (Vit.D3), a well-known differentiating agent for myelomonocytic cells which has been previously reported to modulate HIV replication in other in vitro systems, induced maturation of U1 cells toward a macrophage-like phenotype, as demonstrated by the induction of the differentiation-associated cell surface markers CD14 and CD11b. Vit.D3-induced differentiation did not result in induction of HIV expression; however, when U1 cells were stimulated with tumor necrosis factor alpha in the presence of Vit.D3, a synergistic induction of cell differentiation and viral expression was demonstrated. In contrast, Vit.D3 suppressed the induction of HIV expression in U1 cells stimulated with gamma interferon, interleukin-6, and granulocyte-macrophage colony-stimulating factor, although synergy between Vit.D3 and these cytokines was observed in terms of cellular differentiation. These data suggest that differentiation of monocytic cells does not necessarily correlate with increased HIV expression.

Activation of mesangial cells by the phosphatase inhibitor vanadate. Potential implications for diabetic nephropathy

The metalion vanadate has insulin-like effects and has been advocated for use in humans as a therapeutic modality for diabetes mellitus. However, since vanadate is a tyrosine phosphatase inhibitor, it may result in undesirable activation of target cells. We studied the effect of vanadate on human mesangial cells, an important target in diabetic nephropathy. Vanadate stimulated DNA synthesis and PDGF B chain gene expression. Vanadate also inhibited total tyrosine phosphatase activity and stimulated tyrosine phosphorylation of a set of cellular proteins. Two chemically and mechanistically dissimilar tyrosine kinase inhibitors, genistein and herbimycin A, blocked DNA synthesis induced by vanadate. Vanadate also stimulated phospholipase C and protein kinase C. Downregulation of protein kinase C abolished vanadate-induced DNA synthesis. Thus, vanadate-induced mitogenesis is dependent on tyrosine kinases and protein kinase C activation. The most likely mechanism for the effect of vanadate on these diverse processes involves the inhibition of cellular phosphotyrosine phosphatases. These studies demonstrating that vanadate activates mesangial cells may have major implications for the therapeutic potential of vanadate administration in diabetes. Although vanadate exerts beneficial insulin-like effects and potentiates the effect of insulin in sensitive tissue, it may result in undesirable activation of other target cells, such as mesangial cells.

Long term follow-up of percutaneous transluminal renal angioplasty with special reference to aorto-arteritis

Percutaneous transluminal renal angioplasty (PTRA) was attempted in 96 patients of renovascular hypertension (RVHT) admitted during the period 1986 to 1992. The patients' age ranged from 14-70 (mean: 38.7 +/- 18.8) years. There were 42 (43.8%) males and 54 (56.2%) females. The cause of renal artery stenosis (RAS) was aorto-arteritis in 44 (45.8%), atherosclerosis in 28 (29.2%) and fibromuscular dysplasia in 24 (25%). Bilateral RAS was found in 16 (16.7%). PTRA was angiographically successful in 92 (95.8%) patients. The mean pressure gradient decreased from 82.6 +/- 8.2 to 11.2 +/- 3.6 mm Hg in aorto-arteritis, 75.2 +/- 13.2 to 9.6 +/- 6.4 mm Hg in atherosclerosis and from 86.4 +/- 10.6 to 13.2 +/- 8.2 mm Hg in fibromuscular dysplasia respectively. The patients were followed up for 43.2 +/- 24.1 (range: 6-77) months. Remission or satisfactory lowering of blood pressure was achieved in 80 (86.9%) patients. Clinical success rate (remission or satisfactory lowering of BP) at the end of follow-up period was 75.3 percent. Randomly selected repeat angiography was done in 45 out of 92 (49.1%) patients at the end of 24 months of follow-up. Restenosis was detected in 12 (26.7%) patients and was commonest in the atherosclerotic group (42.8%), followed by fibromuscular dysplasia (14.3%) and least common in aorto-arteritis (11.8%). Repeat angioplasty was done successfully in 10 (83.3%) patients.(ABSTRACT TRUNCATED AT 250 WORDS)

A family of serine proteases expressed exclusively in myelo-monocytic cells specifically processes the nuclear factor-kappa B subunit p65 in vitro and may impair human immunodeficiency virus replication in these cells

Two groups of U937 promonocytic cells were obtained by limiting dilution cloning which differed strikingly in their ability to support human immunodeficiency virus 1 (HIV-1) replication. "Plus" clones replicated the virus efficiently, whereas "minus" clones did not. We examined these clones for differences in nuclear factor (NF)-kappa B activity which might account for the observed phenomenon. Stimulation of plus clones liberated the classical p50-p65 complex from cytoplasmic pools, whereas minus clones produced an apparently novel, faster-migrating complex, as judged by electrophoretic mobility shift assays. It is surprising that the faster-migrating complex was composed also of p50 and p65. However, the p65 subunit was COOH-terminally truncated, as shown by immunoprecipitation. The truncation resulted from limited proteolysis of p65 during cellular extraction which released particular lysosomal serine proteases, such as elastase, cathepsin G, and proteinase 3. These specific proteases are coordinately expressed and were present exclusively in the minus U937 clones, but not in the plus clones, as demonstrated in the case of cathepsin G. In addition, these proteases were detected in certain subclones of THP-1 and HL-60 cells and in primary monocytes, in each case correlating with the truncated from of p65. We demonstrate in vitro cleavage of p65 by purified elastase and cathepsin G. It is possible that particular serine proteases may have inhibiting effects on the replication of HIV-1 in myelo-monocytic cells. The data also demonstrate that special precautions must be taken when making extracts from myelo-monocytic cells.

Mitogenic signaling of thrombin in mesangial cells: role of tyrosine phosphorylation

Thrombin elicits multiple biological effects on a variety of cells. We have previously shown that thrombin is a potent mitogen for human glomerular mesangial cells. This mitogenic effect of thrombin is associated with activation of phospholipase C (PLC) and induction of platelet-derived growth factor (PDGF) gene expression. The thrombin receptor, which belongs to the guanine nucleotide binding protein (G protein)-coupled receptor family, has recently been shown to induce rapid tyrosine phosphorylation of cellular proteins. In the present study, we investigated the role of protein-tyrosine phosphorylation in mediating the cellular responses elicited by thrombin in human glomerular mesangial cells. Amino acid labeling followed by immunoprecipitation with phosphotyrosine antibodies demonstrate that thrombin stimulates tyrosine phosphorylation of a set of cellular proteins. Treatment of mesangial cells with thrombin followed by immunoblotting with phosphotyrosine antibodies showed three major bands of tyrosine-phosphorylated proteins approximately 130, 70, and 44-42 kDa. Phosphorylation of these proteins was inhibited by two tyrosine kinase inhibitors, herbimycin A and genistein. Both compounds inhibited DNA synthesis and PDGF B-chain gene expression but had no effect on inositol phosphates production or increases in cytosolic calcium in response to thrombin. These data demonstrate that protein-tyrosine phosphorylation is not required for thrombin-induced PLC activation with inositol phosphate formation and subsequent intracellular calcium release, but it is an absolute requirement for thrombin-induced DNA synthesis and PDGF B-chain gene expression.

Interferons in the pathogenesis and treatment of human immunodeficiency virus infection

There still remains several unanswered questions concerning the pathogenesis of human immunodeficiency virus (HIV) infection. Interferons (IFNs), as well as other cytokines, are both dysregulated in HIV infection and serve as effector molecules that modulate the replicative capacity of HIV. Acid-labile IFN-alpha, an aberrant form of interferon earlier described in certain autoimmune diseases, has been detected in HIV-infected individuals. Conversely, a deficient expression of IFN-alpha may occur usually associated with HIV disease. Although conflicting findings have been reported on whether IFN-gamma, a product of activated T and natural killer (NK) cells, is elevated in the peripheral blood (PB) compartment, high levels of its expression have been observed in the germinal centers of the lymph nodes during HIV disease. IFN-alpha and IFN-beta have shown potent anti-retroviral effects in several in vitro systems of both acute and chronic HIV infection. These findings have served as the basis of the rationale for their therapeutic application, resulting in some positive effects at least in those patients with relatively high CD4+ T cell counts and healthy immune functions. Furthermore, IFN-alpha has shown important therapeutic effects on HIV-associated Kaposi's sarcoma (KS). Both suppressive and inductive effects on HIV replication in vitro have been described for IFN-gamma, whereas no clear clinical benefits have been reported following its administration to HIV-infected individuals. In conclusion, IFNs are involved in several pathogenic aspects of HIV infection and AIDS, and certain IFNs may serve as important tools to limit the spread of the virus and the progression of disease.

PDGF-mediated activation of phosphatidylinositol 3 kinase in human mesangial cells

Platelet-derived growth factor (PDGF) stimulates mitogenesis and exerts other biologic activities in glomerular mesangial cells. The precise mechanism of PDGF-induced mitogenesis in these cells is not clear. The activation of a signal transducing enzyme, phosphatidylinositol 3 kinase (PI 3 kinase) is associated with mitogenesis. Activation of PI 3 kinase results from stimulation of tyrosine kinase and G-protein-coupled classes of receptors. The synthesis of D3 phosphorylated inositides, the products of this enzymatic reaction, in non-nucleated cells such as blood platelets is dependent upon protein kinase C activation and G-proteins. We studied the activation of PI 3 kinase in response to PDGF in human glomerular mesangial cells. Using a PI 3 kinase 85 kD subunit specific antibody, we detected mesangial cell PI 3 kinase protein as 110 and 85 kD heterodimer. PDGF stimulated PI 3 kinase activity in antiphosphotyrosine immunoprecipitates in a dose-dependent manner showing maximum activation at 12 ng/ml. The antiphosphotyrosine associated PI 3 kinase activity showed biphasic kinetics with a fast peak within two minutes followed by a second peak at 10 minutes. Antiphosphotyrosine and PI 3 kinase immunoprecipitation studies indicated the association of the 85 kD PI 3 kinase subunit with PDGFR. Direct immunoprecipitation with PDGFR beta antibody showed the association of PI 3 kinase activity with the PDGF-receptor. The isoquinoline sulfonyl piperazine compound H7 at concentrations that inhibit PDGF-stimulated PKC activity had no effect on PDGF-stimulated PI 3 kinase activity in antiphospotyrosine immunoprecipitates. These data indicate that PI3 kinase activation is insensitive to PKC. Treatment of mesangial cells with pertussis toxin at concentrations that partially inhibited PDGF-induced DNA synthesis in human mesangial cells did not inhibit PDGF-induced PI 3 kinase activation. These data indicate that PDGF activates PI 3 kinase in mesangial cells and that pertussis toxin-sensitive G-proteins are not involved in PI 3 kinase activation. The data further dissociate activation of PI 3 kinase from mitogenesis in human mesangial cells.

Cytokine-mediated induction of human immunodeficiency virus (HIV) expression and cell death in chronically infected U1 cells: do tumor necrosis factor alpha and gamma interferon selectively kill HIV-infected cells?

Infection with several DNA or RNA viruses induces a state of increased sensitivity to cell lysis mediated by tumor necrosis factor (TNF), particularly in the presence of gamma interferon (IFN-gamma). Infection of human cells with the human immunodeficiency virus (HIV) may induce a similar phenomenon. However, TNF and IFN-gamma are known upregulators of HIV replication, raising the question of the potential role of these cytokines in the selective elimination of cells infected with this virus. The present study demonstrates that chronically infected U1 cells were killed with much greater efficiency by costimulation with TNF-alpha and IFN-gamma than their uninfected parental cell line U937. However, synergistic induction of viral expression also occurred in U1 cells as a consequence of treatment with the two cytokines. Cell death in U1 cells was not caused by the massive production of virions, in that costimulation with glucocorticoid hormones and TNF-alpha or IFN-gamma resulted in high levels of virion production without cytopathicity. To investigate the nature of the selective cytotoxic effect observed in U1 cells costimulated with TNF-alpha plus IFN-gamma, a panel of uninfected cell clones was generated by limiting dilution of U937 cells and tested for response to TNF-alpha and/or IFN-gamma. In contrast to the uncloned bulk parental U937 cell line, most uninfected cell clones showed a very high susceptibility to being killed by TNF-alpha and IFN-gamma. Similar findings were obtained when both infected U1 cells and several uninfected U937 cell clones were costimulated with an anti-Fas monoclonal antibody in the presence of IFN-gamma, although, unlike cells stimulated with TNF-alpha, cells treated with anti-Fas antibody did not express virus. Therefore, the increased susceptibility to cytokine-mediated lysis observed in cell lines infected with HIV is likely due to the selection of preexisting cell clones rather than viral infection.

Involvement of PKC-alpha in PDGF-mediated mitogenic signaling in human mesangial cells

Platelet-derived growth factor (PDGF) is a potent mitogen for a variety of cells. The calcium/phospholipid-dependent protein kinase C (PKC) represents a major signal transduction pathway for many growth stimuli including PDGF. Various isoforms of PKC are differentially expressed in the same or in different cells and tissues, and diverse stimuli may selectively activate one or more PKC isoforms. We studied the effect of PDGF on DNA synthesis and on the activity of PKC in human mesangial cells and vascular pericytes in the glomerular microvascular bed. PKC activity was measured as the amount of phosphorylated myelin basic protein-derived peptide substrate in the absence and presence of an inhibitor, a peptide spanning the pseudosubstrate region of PKC. PDGF (15 ng/ml) stimulated PKC activity within 5 min, and the effect was sustained for 60 min. Pretreatment of mesangial cells with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), an inhibitor of PKC, abolished the stimulation of PKC and DNA synthesis in response to PDGF. This effect of H-7 was specific, because H-7 did not inhibit the tyrosine phosphorylation of the PDGF receptor in vivo when added to the cells or the in vitro kinase activity in the PDGF beta-receptor immunoprecipitates. Utilizing isotype-specific antibodies against PKC-alpha, -beta, or -gamma for immunoprecipitation of PDGF-treated mesangial cell extracts, followed by assay of PKC activity, we demonstrated the activation of PKC-alpha only. Northern blot analysis of mRNA prepared from mesangial cells also revealed two transcripts, 3.7 kb and 1.8 kb, that hybridized with cDNA specific for PKC-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Simvastatin inhibits PDGF-induced DNA synthesis in human glomerular mesangial cells

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A-(HMGCoA) reductase ameliorate glomerular pathology and renal dysfunction in different models of glomerular disease. This effect has generally been attributed to a decrease in the circulating levels of cholesterol. Focal or diffuse mesangial cell proliferation is a common feature of glomerular pathology. There is now evidence from studies in vitro and in vivo that platelet-derived growth factor (PDGF) is an important mediator of glomerular hypercellularity. The activity of HMGCoA reductase has previously been shown to be a requirement for cell growth. In the present study, we examined the effect of simvastatin, and HMGCoA reductase inhibitor, on PDGF-induced DNA synthesis and PDGF B chain gene expression in human glomerular mesangial cells. In addition, we investigated the effect of simvastatin on phospholipase C (PLC) and protein kinase C (PKC) activation stimulated by PDGF. We demonstrate that treatment of the cells with simvastatin completely inhibits PDGF-induced DNA synthesis. This inhibition is reversed by mevalonate but not by cholesterol or farnesol, two major metabolites of the mevalonate pathway. On the other hand inhibition of HMGCoA reductase does not influence PDGF-induced activation of PLC and PKC, or PDGF B chain gene expression. These data suggest that simvastatin acts at a late step in the PDGF mitogenic pathway without interfering with other early cellular responses elicited by this growth factor. These studies also raise the possibility that the ameliorative effect of HMGCoA reductase inhibitors on glomerular pathology may be mediated, at least in part, by a direct cellular effect.

Glucocorticoids synergize with tumor necrosis factor alpha in the induction of HIV expression from a chronically infected promonocytic cell line

In this study we have investigated the effects of glucocorticoids (GCs) on the expression of human immunodeficiency virus (HIV) in a chronically infected promonocytic cell line, U1. Although no increase in virus production was observed in U1 cells stimulated with physiological concentrations of GC alone, costimulation with dexamethasone plus tumor necrosis factor alpha (TNF-alpha) synergistically enhanced TNF-alpha-dependent HIV expression. Molecular analysis demonstrated that GCs plus TNF-alpha resulted in an accumulation of steady state HIV RNA secondary to either an increase in transcription or an increase in message stability. These findings may be of physiological relevance because GCs are used in the treatment of certain disorders associated with HIV infection and TNF-alpha levels have been reported to be elevated in the plasma and cerebrospinal fluid of certain HIV-infected individuals.

Interferon gamma induces the expression of human immunodeficiency virus in persistently infected promonocytic cells (U1) and redirects the production of virions to intracytoplasmic vacuoles in phorbol myristate acetate-differentiated U1 cells

Interferon gamma (IFN-gamma), a lymphokine that exerts multiple immunoregulatory effects, has been found to be elevated in the plasma, cerebrospinal fluid, and lymph nodes of human immunodeficiency virus (HIV)-infected individuals and has shown variable effects on HIV replication in acutely infected cells. In the present study, we have demonstrated that IFN-gamma is a potent modulator of HIV expression in persistently infected U1 promonocytic cells in which virus production is characterized by a constitutive state of relative latency. Direct stimulation of U1 cells with IFN-gamma (10-1,000 U/ml) activated HIV expression, as measured by reverse transcriptase (RT) activity in the culture supernatant and increased levels of cell-associated viral protein and mRNAs. These effects on virus expression were not accounted for by the induction of endogenous TNF-alpha secretion, as previously described in U1 cells stimulated with phorbol myristate acetate (PMA). At the ultrastructural level, the stimulatory activity of IFN-gamma was correlated with HIV particle production in intracytoplasmic vacuoles along with the differentiation of U1 into macrophage-like cells. Furthermore, costimulation of U1 cells with IFN-gamma and PMA significantly increased the accumulation of vacuole-associated HIV concomitant with decreasing membrane-associated particles and RT activity production, as compared with cells stimulated with PMA alone. No evidence of spontaneous secretion of intracellular vacuole-associated virus was obtained by kinetic analysis of the RT activity released in the supernatants throughout the culture period unless cells were deliberately disrupted. These findings suggest that vacuole-associated virions likely represent a relatively stable intracellular reservoir of HIV, as previously described in primary macrophages infected in vitro or in infected macrophages in the brains of patients with acquired immune deficiency syndrome. The reduced levels of RT activity observed in the culture supernatants of U1 cells stimulated with PMA in the presence of IFN-gamma were not indicative of a suppressive effect of IFN-gamma on PMA-induced expression of HIV proteins and mRNAs, either directly or mediated by the release of IFN-alpha/beta. This study suggests that IFN-gamma may play an important role as an inducer of HIV expression in infected mononuclear phagocytes.

Allergen- and bacterial antigen-specific T-cell clones established from atopic donors show a different profile of cytokine production

We have established a large panel of T-cell clones (TCCs) specific for Dermatophagoides pteronyssinus and Lolium perenne group I grass pollen allergens (total, 61) and for tetanus toxoid and protein purified derivative bacterial antigens (total, 38) from the peripheral blood of two atopic individuals and then analyzed their ability to produce interleukin 4 (IL-4), IL-5, and interferon gamma (IFN-gamma). Upon stimulation with phorbol 12-myristate 13-acetate plus anti-CD3 antibody, the great majority of TCCs specific for bacterial components was able to produce both IL-4 and IFN-gamma, whereas most D. pteronyssinus- and L. perenne group I-specific TCCs produced IL-4, but no, or limited, IFN-gamma. Moreover, the mean amounts of IL-4 and IFN-gamma released by allergen-specific TCCs were significantly higher and lower, respectively, than the mean amounts produced by TCCs specific for bacterial components. Under the same experimental conditions, virtually all allergen-specific TCCs, but only one-third of tested TCCs specific for bacterial components, expressed IL-5 RNA and secreted IL-5 in their supernatants. Eighteen TCCs (nine specific for allergens and nine specific for bacterial components) were also assessed for their ability to induce IgE synthesis by autologous B cells in response to stimulation with the specific antigen. Under these experimental conditions, all allergen-specific TCCs, but only one-third of TCCs specific for bacterial components that produced IL-4 but no, or little, IFN-gamma induced the synthesis of detectable amounts of IgE. The demonstration that most allergen-specific helper T cells in atopic individuals are able to produce high amounts of IL-4 (and IL-5), but no IFN-gamma, may explain why allergens induce production of IgE antibodies and increase eosinophils.

Accumulation of Th-2-like helper T cells in the conjunctiva of patients with vernal conjunctivitis

A total number of 132 T cell clones (TCC) were obtained by PHA-stimulation of single T cells from mononuclear cell suspensions of conjunctival flogistic infiltrates of three patients with vernal conjunctivitis (VC). The phenotype and functional properties of these TCC were compared with those of 122 TCC contemporarily established from PB mononuclear cell suspensions of the same patients, 120 TCC established from lymph nodes of three patients with nonspecific hyperplastic lymphoadenitis and 159 TCC established from thyroid lymphocyte infiltrates of three patients with Graves' disease. The great majority of conjunctival TCC displayed the CD4+ CD8- phenotype (CD4/CD8 ratios ranging from 6.1 to 7.0), whereas the mean CD4/CD8 ratios for control TCC ranged from 0.9 to 2.4. After stimulation with either PHA or PMA plus anti-CD3 mAb, conjunctival TCC differed from control TCC for their ability to produce cytokines. In particular, a large number of conjunctival TCC produced IL-4, but no, or limited amounts of, IFN-gamma, whereas no difference was observed between conjunctival and control TCC with regard to the production of IL-2. The failure of IFN-gamma production by conjunctival TCC was apparently not caused by delay or block in cytokine production, but actually reflected the lack of IFN-gamma transcription. Virtually all conjunctival TCC able to produce IL-4, but not IFN-gamma, as well as most of those producing both cytokines, provided helper function for IgE synthesis in allogeneic normal B cells. The accumulation in the conjunctiva of patients with vernal conjunctivitis of CD4+ T cells that, apart from the production of IL-2, resembles murine Th2 cells for their profile of cytokine production and helper function suggests a possible role for these cells in the pathogenesis of the disease.

Accumulation of Th-2-like helper T cells in the conjunctiva of patients with vernal conjunctivitis

A total number of 132 T cell clones (TCC) were obtained by PHA-stimulation of single T cells from mononuclear cell suspensions of conjunctival flogistic infiltrates of three patients with vernal conjunctivitis (VC). The phenotype and functional properties of these TCC were compared with those of 122 TCC contemporarily established from PB mononuclear cell suspensions of the same patients, 120 TCC established from lymph nodes of three patients with nonspecific hyperplastic lymphoadenitis and 159 TCC established from thyroid lymphocyte infiltrates of three patients with Graves' disease. The great majority of conjunctival TCC displayed the CD4+ CD8- phenotype (CD4/CD8 ratios ranging from 6.1 to 7.0), whereas the mean CD4/CD8 ratios for control TCC ranged from 0.9 to 2.4. After stimulation with either PHA or PMA plus anti-CD3 mAb, conjunctival TCC differed from control TCC for their ability to produce cytokines. In particular, a large number of conjunctival TCC produced IL-4, but no, or limited amounts of, IFN-gamma, whereas no difference was observed between conjunctival and control TCC with regard to the production of IL-2. The failure of IFN-gamma production by conjunctival TCC was apparently not caused by delay or block in cytokine production, but actually reflected the lack of IFN-gamma transcription. Virtually all conjunctival TCC able to produce IL-4, but not IFN-gamma, as well as most of those producing both cytokines, provided helper function for IgE synthesis in allogeneic normal B cells. The accumulation in the conjunctiva of patients with vernal conjunctivitis of CD4+ T cells that, apart from the production of IL-2, resembles murine Th2 cells for their profile of cytokine production and helper function suggests a possible role for these cells in the pathogenesis of the disease.

In vitro infection with HIV of antigen-specific T cell clones derived from HIV-seronegative individuals. Effects on cytokine production and helper function

Three human T cell clones (TCC) specific for purified protein derivative of Mycobacterium tuberculosis were incubated in the presence of polybrene and phytohemagglutinin with irradiated mononuclear cells from one individual exhibiting seropositivity for human immunodeficiency virus (HIV) and high levels of circulating p24 antigen. After three weeks, TCC showed HIV integration in their DNA, as shown by polymerase chain reaction analysis and Southern blot technique. All the three HIV-infected TCC maintained their ability to recognize the specific antigen, even if their proliferative ability was reduced. The ability of the HIV-infected TCC to produce IL-2, IL-4 and IFN-gamma in response to phorbol myristate acetate plus anti-CD3 monoclonal antibody was decreased, whereas their ability to produce TNF-alpha was unaffected or even enhanced. Two out of the three HIV-infected TCC showed the ability to provide helper function for polyclonal immunoglobulin production when cocultured with autologous B cells in the absence of any stimulant. These data suggest that in vitro infection of normal human TCC may provide a useful model for the study of immunological alterations induced by HIV.

Noncognate contact-dependent B cell activation can promote IL-4-dependent in vitro human IgE synthesis

We have previously shown that IL-4 is an essential mediator for the synthesis of human IgE in vitro. In this study we demonstrate that prior physical contact with T cells is required by B cells to synthesize IgE in response to IL-4. Both autologous and allogeneic freshly prepared T cells were consistently able to support IL-4-dependent IgE synthesis, provided that they were added to B cells together with, or before, the addition of IL-4. In addition, most CD4+, as well as a proportion of CD8+, PHA-induced T cell clones (TCC) established from two HLA-DR incompatible donors, supported, in the presence of exogenous IL-4, the synthesis of IgE in B cells from the majority of individuals tested including both donors of cloned T cells. An alloreactive TCC able to produce IL-4 in response to HLA-DR4+ B cells and to induce HLA-DR4+ B cells to synthesize IgE, acquired the ability to support IgE synthesis by B cells lacking the appropriate alloantigen provided that exogenous IL-4 was added. Although the ability of freshly prepared T cells to support IgE synthesis was consistently abrogated by fixation with paraformaldehyde (PF), such a treatment variably affected the IgE-inducing ability of TCC. Preactivation with anti-CD3 before treatment with PF maintained or even enhanced the ability of TCC to support IL-4-dependent IgE synthesis. More importantly, preactivation with anti-CD3, followed by fixation with PF, enabled TCC, apparently devoid of IgE-inducing activity in unfixed condition, to support IL-4-dependent IgE synthesis. Taken together these data suggest that at least two signals are involved in the triggering of human B cells to IgE production: the first is delivered by a T-B cell contact and the second by IL-4. The physical signal delivered by T cells does not necessarily consist of cognate interaction. Non-cognate contact-dependent induction of B cells to IgE synthesis in response to IL-4 appears to be related to molecule(s) distinct from the TCR/CD3 complex, but fully expressed on the membrane of TCR/CD3-activated T cells.

Noncognate contact-dependent B cell activation can promote IL-4-dependent in vitro human IgE synthesis

We have previously shown that IL-4 is an essential mediator for the synthesis of human IgE in vitro. In this study we demonstrate that prior physical contact with T cells is required by B cells to synthesize IgE in response to IL-4. Both autologous and allogeneic freshly prepared T cells were consistently able to support IL-4-dependent IgE synthesis, provided that they were added to B cells together with, or before, the addition of IL-4. In addition, most CD4+, as well as a proportion of CD8+, PHA-induced T cell clones (TCC) established from two HLA-DR incompatible donors, supported, in the presence of exogenous IL-4, the synthesis of IgE in B cells from the majority of individuals tested including both donors of cloned T cells. An alloreactive TCC able to produce IL-4 in response to HLA-DR4+ B cells and to induce HLA-DR4+ B cells to synthesize IgE, acquired the ability to support IgE synthesis by B cells lacking the appropriate alloantigen provided that exogenous IL-4 was added. Although the ability of freshly prepared T cells to support IgE synthesis was consistently abrogated by fixation with paraformaldehyde (PF), such a treatment variably affected the IgE-inducing ability of TCC. Preactivation with anti-CD3 before treatment with PF maintained or even enhanced the ability of TCC to support IL-4-dependent IgE synthesis. More importantly, preactivation with anti-CD3, followed by fixation with PF, enabled TCC, apparently devoid of IgE-inducing activity in unfixed condition, to support IL-4-dependent IgE synthesis. Taken together these data suggest that at least two signals are involved in the triggering of human B cells to IgE production: the first is delivered by a T-B cell contact and the second by IL-4. The physical signal delivered by T cells does not necessarily consist of cognate interaction. Non-cognate contact-dependent induction of B cells to IgE synthesis in response to IL-4 appears to be related to molecule(s) distinct from the TCR/CD3 complex, but fully expressed on the membrane of TCR/CD3-activated T cells.

Role for T cells, IL-2 and IL-6 in the IL-4-dependent in vitro human IgE synthesis

The role of T cells and monocytes, as well as that of cytokines, such as IL-1, IL-2 and IL-6, on the IL-4-dependent in vitro human IgE synthesis was investigated. Recombinant IL-4, IL-4-containing T-cell clone supernatants and different combinations of recombinant cytokines failed to induce highly purified B cells to synthesize IgE. IL-4-dependent IgE synthesis was restored by addition to purified B cells of either untreated or mitomycin C-treated autologous T lymphocytes. Addition to purified B cells of autologous monocytes did not restore the IgE response, but usually it exerted a potentiating effect on the synthesis of IgE induced by IL-4 in the presence of suboptimal concentrations of T cells. The activity of T cells apparently preceded that of IL-4 and required a physical contact with B cells. The presence in culture of IL-2 also appeared to be necessary for the T-cell and IL-4-dependent IgE synthesis. Even though not essential, IL-6 was able to potentiate IgE synthesis in most experiments, whereas IL-1 did not display any modulatory effect.

Role of interleukins in induction and regulation of human IgE

The studies on human IgE synthesis here summarized provide further insight into the cellular and molecular mechanisms involved in IgE regulation, as well as in the alterations responsible for IgE disregulation in some pathological conditions. They have clearly demonstrated that IL-4 is the essential factor for the induction of human IgE synthesis, since no substantial IgE production in vitro could be obtained in the absence of this lymphokine. Another T cell-derived lymphokine, IFN gamma, negatively regulates the IgE synthesis induced by IL-4. These two lymphokines can be produced by different T helper cells, as shown in mice, but they can also be the product of the same T cell clones. In such a case, the possibility that a given clone provides helper function for IgE seems to be dependent on the balance between the amounts of the two lymphokines produced. The IgE helper activity of rIL-4 appeared to be dependent on the presence in culture of appropriate concentrations of T lymphocytes, suggesting that T-B cell contact or other interleukins, such as IL-2 and IL-6, are needed in IL-4-dependent IgE synthesis. Finally, alterations of one or more of these regulatory mechanisms may play a crucial role in the pathogenesis of diseases characterized by a hyperproduction of IgE.

Increased production of IgE protein and IgE antibodies specific for fungal antigens in patients with the acquired immunodeficiency syndrome

Levels of IgE protein and IgE antibodies specific for 8 different allergenic extracts were measured in the serum of a large series of patients infected by the human immunodeficiency virus (HIV) and in HIV-seronegative subjects belonging to the same risk groups (intravenous drug-users, homosexual men and hemophiliacs). The proportion of subjects showing elevated IgE levels was higher among HIV-infected patients with group IV disease than among HIV-infected patients with group II-III diseases or seronegative individuals. In addition, many HIV-infected patients with elevated IgE levels showed the presence in their serum of IgE antibodies specific for fungal antigens.