Activation of the human immunodeficiency virus long terminal repeat in THP-1 cells by a staphylococcal extracellular product.

Staphylococcal strains can release a factor that strongly activates the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) in THP-1 cells transfected with the HIV-1 LTR-driven luciferase reporter gene (THP-1 LTRluc). The factor is present in the overnight culture fluid and is readily released from the organisms into aqueous medium by vigorous mixing. Staphylococcal extracellular material is a complex mixture of polysaccharide and protein containing peptidoglycan and teichoic acid, released in part by cell wall turnover. The importance of the carbohydrate component is emphasized by concanavalin A (Con A) inhibition of staphylococcal product-induced LTR activation but not of activation by phorbol 12-myristate 13-acetate or tumor necrosis factor. The effect of Con A was decreased or abolished by sugars in the order methyl alpha-D-mannopyranoside > methyl alpha-D-glucopyranoside > mannose > glucose = fructose > N-acetylglucosamine. Wheat germ agglutinin was less inhibitory than Con A; in this instance N-acetylglucosamine decreased inhibition, whereas methyl alpha-D-mannopyranoside or methyl alpha-D-glucopyranoside did not. The induction of luciferase activity in THP-1 LTRluc by the staphylococcal extracellular product also was inhibited by fetal bovine and normal human serum. A comparison of 31 staphylococcal isolates (9 Staphylococcus aureus, 11 Staphylococcus epidermidis, 2 Staphylococcus haemolyticus, 4 Staphylococcus hominis, 2 Staphylococcus capitis, 2 Staphylococcus warneri, 1 Staphylococcus saprophyticus) revealed wide variation in LTR activating activity that did not correlate closely with slime production. Our findings, using induction of luciferase in THP-1 LTRluc as a model for upregulation of HIV infection, raise the possibility that staphylococci, as well as certain other microorganisms, release carbohydrate-containing exopolymers, which can activate the HIV-1 LTR, thus influencing progression of HIV infection.

Stimulation of the bactericidal activity of polymorphonuclear leukocytes by manganese.

An antioxidant effect of manganese (Mn) complexes due to the scavenging of the superoxide anion (O2-.) or to the decomposition of hydrogen peroxide (H2O2) has been described. We report here that Mn also can exert a prooxidant effect under certain experimental conditions. Thus Mn2+ in phosphate buffer increased the bactericidal effect of phorbol myristate acetate-stimulated polymorphonuclear leukocytes (PMNs) on extracellular Escherichia coli. This effect was inhibited by azide, catalase, and a decrease in chloride concentration and was not observed when normal PMNs were replaced by those of patients with chronic granulomatous disease or myeloperoxidase (MPO) deficiency. Mn2+ could be replaced by Mn3+ or by superoxide dismutase (SOD). These findings suggest that Mn (or SOD), by increasing the conversion of O2-. to H2O2, can increase the activity of the MPO-H2O2-chloride antimicrobial system released by stimulated PMNs.

Effects of gamma-interferon on human neutrophils: protection from deterioration on storage.

Human polymorphonuclear leukocytes (PMN) preincubated overnight with 100 U/mL gamma-interferon (IFN-gamma) had an increased metabolic response, as measured by iodination and/or superoxide production, to stimulation by tumor necrosis factor (TNF), granulocyte-macrophage colony-stimulating factor (GM-CSF), formylmethionyl-leucyl-phenylalanine (FMLP), opsonized zymosan, and lipopolysaccharide (LPS), as compared with cells comparably preincubated in the absence of IFN-gamma. The decline in the staphylocidal activity of the stored PMN was also prevented in part by IFN-gamma, as was the depressed adherence of PMN stimulated with phorbol myristate acetate (PMA), FMLP, TNF, GM-CSF, and LPS. This protective effect of IFN-gamma on PMN function was associated with the prolonged surface expression of the complement receptor three (CR3) alpha-chain (CD11b), CR3 beta-chain (CD18), FcRII (CD32), and FcRIII (CD16), and the appearance of surface FcRI (CD64). The polymerase chain reaction (PCR) was used to amplify neutrophil RNA-derived cDNA recognized by synthetic oliogonucleotides designed from published nucleotide sequences for specific proteins. Using this procedure, mRNA for gp91-phox, p67-phox, p47-phox, CD64, two forms of CD32, CD16, CD11b, CD18, and actin were found to be depressed after overnight storage of neutrophils, and this decrease in steady-state mRNA levels was in part or totally prevented by IFN-gamma. CD64 and gp91-phox mRNA were generally increased by IFN-gamma to a level greater than that of freshly isolated neutrophils. Northern analysis of CD64 and p47 phox mRNAs confirmed the findings with the PCR method. These findings suggest that storage of PMN in a functionally active state is favored by the presence of IFN-gamma.