Candida albicans and HIV-1 Infection

Candida albicans virulence is in part mediated by fibronectin (FN) interaction. We compared the adherence level to FN (using Becton Dickinson FN-coated plates) of several strains of yeast isolated from HIV-1 infected or uninfected subjects affected by candidiasis (30 strains from HIV+ subjects and 18 from HIV- subjects). More adhesive strains were found in HIV+ patients than in HIV- subjects. In particular a mean increase of 120 per cent as regards the total number of adhesive cells and 230 per cent as regards the adhesive cells producing germ tubes was detected in the former group of strains as compared to the latter ( p < 0.001 in both cases). The enhancement of FN expression induced by HIV-1 infection, as we have previously demonstrated, can increase interest in the adherence to FN of C. albicans strains isolated from AIDS-affected patients. Moreover, we also underline the important role played by HIV Nef protein in increasing the C. albicans aggressiveness. In fact a significant inhibitory effect of Nef on the phagocytosis of this yeast by macrophages has been demonstrated and the oxidative processes of these cells seem to be down-regulated by this protein.

Multifunctional activity of recombinant p14 on lymphoid cell cultures

Some effects of recombinant p14, a protein encoded by the tat gene of immunodeficiency virus type 1 (HIV-1), were investigated on T lymphocytic cell cultures. In particular, we detected p14 adsorption to cells, the rate of cell replication, the expression of fibronectin (FN) and its receptor (FNR) and of cell surface CD4 antigen in HIV-1-infected or uninfected MT-4 and H9 cells, treated with p14. Moreover, we evaluated the proportion of apoptotic cells in uninfected and chronically infected H9 cells in the presence of p14 and the modulation of interferon (IFN) production induced by p14 in PBMC of healthy subjects. The results obtained demonstrate that p14 exerts multifunctional activities on HIV-1 infected and uninfected cells. In particular, this protein interacts in a specific manner with cell surface, especially with that of infected cells, and enhances the expression of FN and FNR but not that of the CD4 lymphocyte antigen. Moreover, p14 increases cell replication, IFN production and can exert a slight modulation of apoptosis. We also propose a model to explain a possible role in HIV-1 infection of the effects of exogenous p14.

Anti-inflammatory response of IL-4, IL-10 and TGF-beta in patients with systemic inflammatory response syndrome

The systemic inflammatory response syndrome (SIRS) is an inflammatory process seen in association with a large number of clinical infective and non-infective conditions. The aim of this study was to investigate the role of anti-inflammatory cytokines such as interleukin-4 (IL-4), interleukin-10 (IL-10), and transforming growth factor-beta (TGF-beta). Serum levels of IL-4, IL-10 and TGF-beta were determined in 45 patients with SIRS: 38 patients had SIRS of infectious origin, whereas seven patients had non-infectious SIRS. Twenty healthy subjects were used as controls. Serum levels of IL-4, IL-10 and TGF-beta were determined by an immunoenzyme assay. A significant increase of IL-4 was observed in these patients at the time of diagnosis and 5 days later. In contrast, serum levels of IL-10 were not increased at the time of diagnosis, but a slight decrease was noted after 5 days. Serum levels of TGF-beta were not increased at time of diagnosis, and a slight increase was observed after 5 days. Serum levels of IL-4 were significantly higher in patients with infectious SIRS at the time of diagnosis, whereas no significant difference between infectious and non-infectious SIRS was noted for serum levels of IL-10 and TGF-beta at the time of diagnosis and 5 days later. During SIRS, serum levels of IL-4 were significantly increased with a significant correlation between IL-4 and mortality, and only levels of IL-4 were significantly increased in the SIRS caused by infectious stimuli.

HRT and breast cancer risk: a clue for interpreting the available data

Epidemiological and biological data on HRT and breast cancer risk are reviewed. Some aspects deserve consideration. (1) The majority of epidemiological data have been gathered from populations where high estrogen doses (> or = 1.25 mg daily of conjugated estrogens) were used as first line therapy. (2) HRT does not increase the risk in overweight women, even in the series in which a risk increase (in longterm users) is found. This could be as a result of the fact that oral estrogens, through their metabolic and hepatocellular effects, reverse some biological features of obesity (e.g. increased insulin-like growth factor I activity and decreased sex hormone binding globulin level) which potentially increase breast cancer risk, so balancing the estrogen stimulation. (3) The progestin addition seems to increase the risk when the 19 nor-testosterone derivatives are used. These androgenic compounds contrast the metabolic and hepatocellular effects of oral estrogens. To sum up, the possibility does exist that even the longterm use of oral estrogens at the right ('low') dose, with the addition of a non-androgenic progestin, will be shown to be associated with a very limited breast cancer risk increase.

Effects of the exogenous Nef protein on HIV-1 target cells

Nef is a multifunctional gene of HIV which can increase virus replication either directly or by modulating the target cell's metabolism. Nevertheless the role of the exogenous Nef protein is not yet well understood. To investigate it, we studied the effects of the recombinant Nef protein on the expression of some antigens of lymphoid T-cells permissive to HIV-1 replication, and on their proliferation and on apoptosis induction. For this purpose, we utilised MT-4 and H9 T-cell lines. We evaluated FN (fibronectin), CD4 and CD71 expression in uninfected and acutely or chronically infected cells, both untreated and treated with Nef. Our studies showed a significant up-regulation of FN especially in uninfected cells, with a dose of 2.5 microg ml(-1); in contrast, a significant down-modulation of CD4 and CD71 both in uninfected and in acutely or chronically infected cells, was detected. The proliferation of H9 uninfected cells was significantly reduced 24 h after treatment with Nef protein in a dose-dependent manner (ranging from 0.02 to 2.5 microg ml(-1)); likewise a significant inhibition of proliferation of acutely and chronically infected cells was evident with 2.5 microg ml(-1). Moreover, we demonstrated a dose-dependent activity of Nef on inducing apoptosis in H9 uninfected cells and no effects of this protein on modulation of INF alpha and gamma production in peripheral blood mononucleated cells of health donors. Nef appeared to be able to increase the effect of apoptotic stimuli. In conclusion, our data suggest that in our experimental system, the exogenous Nef protein can inhibit cellular synthesis facilitating the metabolic pathway involved in virus replication. In addition it modulates the susceptibility to the HIV-1 infection and finally, that apoptosis induction or enhancement can facilitate the release of neoformed virions.

Effect of Aspergillus terreus mycotoxins on nitric oxide synthase activity in human erythroid K-562 cells

Because several stimuli of microbial origin enhance the activity of nitric oxide synthase (NOS) in human cells of the myeloid lineage, we decided to investigate whether cellular damage induced by Aspergillus terreus mycotoxins could be associated with an increase in NOS activity. A pool of mycotoxins rather than individual toxins was tested so that the natural conditions could be mimicked. In the present study, we report that a crude extract of A. terreus induces cellular damage and increases NOS activity in K-562 cells, an erythroleukaemic cell line in which NOS is particularly active. The specificity of this association was further investigated by using NOS inhibitors and by comparing, in the same cellular model, the effects of the extract with the activity of other microbial toxins of a defined mechanism of action. Canavanine, an inhibitor of NOS, significantly reduced cell death in the presence of the extract, suggesting that cellular damage, induced by the mycotoxins of A. terreus is at least in part mediated by NOS activity. Moreover, Escherichia coli lipopolysaccharide (LPS), known to be a potent NOS inducer, increased NOS activity in our experimental model as well. In contrast, Bordetella pertussis toxin did not show any effect on NOS activity. The results of this study suggest that NOS may be involved in mycotoxicoses.

Levels of circulating nitrate/nitrite and gamma interferon not increased in uncomplicated malaria

The purpose of this study was to evaluate nitric oxide (NO) activity in patients with uncomplicated malaria. Lipopolysaccharide and gamma interferon (IFN-gamma) are potent inducers of NO by inducing production of NO synthase. NO activity was determined by measuring serum levels of nitrite/nitrate (metabolic end products of NO), and IFN-gamma in patients with uncomplicated malaria, mostly caused by Plasmodium falciparum. Neither serum levels of nitrite/nitrate nor of IFN-gamma were significantly increased in patients with uncomplicated malaria, especially in patients with P. falciparum infection, and in those with high parasitaemia. These results show that NO cannot play a role in uncomplicated malaria, and it is still debatable if NO production in this infection has beneficial or detrimental effects.

Insulin-like growth factor I (IGF-I) serum level modifications during transdermal estradiol treatment in postmenopausal women: a possible bimodal effect depending on basal IGF-I values

The objective of this study was to determine the influence of transdermal estradiol administration on insulin-like growth factor I (IGF-I) serum level in a series larger than those published to date. Thirty-nine postmenopausal women with vasomotor symptoms were studied; blood samples (after overnight fast) were obtained just before and at the 6th month of treatment with transdermal estradiol 0.05 mg/day, and serum levels of IGF-I, growth hormone and sex hormone binding globulin (SHBG) were evaluated. Sixteen of the 39 women did not show variations of IGF-I values (group A), while 11 showed an increase (group B) and 12 showed a decrease (group C) by at least 20% with transdermal estradiol treatment. IGF-I basal levels were higher in group C as compared to group A (p < 0.05) and to group B (p < 0.01), intermediate in group A, and lower in group B. Group C showed a significant increase of SHBG values with transdermal estradiol treatment. Transdermal estradiol seems to induce a bimodal effect on IGF-I serum levels, depending on IGF-I basal values. This could be caused by a different responsivity to estrogen action on the liver (the major site of circulating IGF-I production) and also, possibly, by a different degree in insulin sensitivity changes caused by estrogen.

Effect of progestins on IGF-I serum level in estrogen-treated postmenopausal women

Insulin-like growth factor I (IGF-I) has a role in the whole-body anabolism and promotes both normal and abnormal cell growth in several tissues. Although IGF-I is also synthesized locally at numerous other sites, the liver does constitute the major site of its synthesis, and circulating IGF-I is mainly of hepatic derivation. The production of IGF-I is stimulated by growth hormone (GH), the secretion of which is influenced by circulating IGF-I level through a negative feed-back mechanism. Oral estrogen treatment causes a significant decrease of the IGF-I serum level, probably through a hepatocellular effect due to the first hepatic passage. Treatment with transdermal estradiol (tdE2) at the currently used doses does not cause, on average, substantial variations in the IGF-I serum level. The addition of an androgenic progestin--with strong hepatocellular actions, opposite to those of estrogen--completely reverses the IGF-I decrease induced by oral estrogens, and even causes a trend to IGF-I increase when tdE2 is used. Conversely, the addition of a non androgenic progestin, like dydrogesterone, does not cause interference with the estrogen effect.

Apoptotic DNA fragmentation, and its in vitro prevention by nicotinamide, in lymphocytes from HIV-1-seropositive patients and in HIV-1-infected MT-4 cells

Apoptosis seems to play an important role in the decline of CD4+ T-cells in patients infected with HIV-1. Moreover, extensive interest in apoptosis comes from the observation that it correlates both with the progression and the severity of HIV-1 infection. A cross-sectional study was made to evaluate whether such correlation may also extend to the early phases of ex vivo apoptosis, after 20 h of culture. DNA fragmentation, a parameter associated with apoptosis, was evaluated with the terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling (TUNEL) technique, which preferentially labels apoptosis in comparison to necrosis. The results obtained indicate that a negative correlation exists between the proportion of lymphocytes exhibiting DNA strand breaks and the absolute number of CD4+ T-cells per microliter. DNA fragmentation was significantly higher in patients with AIDS or advanced HIV-1 infection as compared to asymptomatic patients or seronegative individuals. No significant difference was found in relation to antiretroviral therapy. Furthermore, the addition of nicotinamide to the cultures significantly reduced DNA fragmentation of both in vitro HIV-1-infected MT-4 cells and lymphocytes from six HIV-1-seropositive individuals. The results of this study confirm that DNA fragmentation, as an early marker of apoptosis, correlates with the severity of HIV-1 infection and suggest that nicotinamide may be involved in the modulation of HIV-1-related apoptosis.

Detection of HIV p24 from antigen presenting monocytes for early diagnosis of HIV-1 infection

The monocytic/macrophagic lineage has an antigen presenting cell function also towards HIV. On the basis of this fact, a new method, indirect immunofluorescence (IIF) for measurement of p24 from monocytes was used. The results were compared to an amplified enzymatic test for serum dissociated p24 detection in 14 HIV negative individuals at risk for HIV and 12 HIV positive patients. Only one seronegative, who had a symptomatic primary HIV infection, had a positive IIF and also an elevated level of p24 in serum. The others had a negative IIF and, 6 months after the specimen, were not positive to the routine methods for detection of anti-HIV antibodies. Seronegative subjects not at risk for HIV were consistently negative to IIF. Among the HIV positive patients 4 were positive to IIF and the remaining 5 were positive to routine methods. Divergent results could be explained by the fact that one test measures cell derived antigen and the other serum antigen and that monocytes can loose APC function in the advanced stages of the illness. The test proved to be cheap and simple, and it is possible to hypothesize an application of it as a support test for the early diagnosis of HIV infection in laboratories not endowed with high levels of technology. Moreover, the results of the amplified p24 ELISA test in 44 seronegative at risk test are reported herein.

Influence of fibronectin on HIV-1 infection and capability of binding to platelets

We have previously demonstrated that fibronectin (FN) can bind HIV-1 envelope proteins, in particular gp 120. The aim of the present study was to determine some biological effects of this phenomenon. Pretreating HIV-1 with human FN increased the infectivity of HIV-1, when a low concentration of the virus was used. In contrast, an RGD-containing pentapeptide (Gly-Arg-Gly-Asp-Ser), which is a fundamental binding site of FN, reduced the infectivity of a suspension of HIV-1 at high concentrations of the virus. It is likely that FN bridges the cell surface and the virions, while the RGD-containing pentapeptide may saturate the HIV-1 binding sites for cell surface receptors. Moreover, gp 120 was bound to the FN present on the surface of platelets. The specificity of this binding was confirmed by the inhibition obtained by pretreating platelets with anti-FN antibodies. The consequence of the surface modifications of the platelets could explain the thrombocytopenia that frequently occurs in patients infected with HIV and suggests also the possibility that platelets could be a vehicle for the virus in the circulation.

In vitro inhibitory activity of citreoviridin against HIV-1 and an HIV-associated opportunist: Candida albicans

Citreoviridin, a mycotoxin produced by some molds of the genera Penicillium and Aspergillus, inhibits the growth of bacteria of the Bacillus genus. Since significant information was not available on the effects of citreoviridin on eukaryotic cells and viruses, this molecule was tested on CD4+ T-lymphoid cell lines, on HIV-1 and on Candida albicans, which sometimes complicates HIV-infection. Antiviral activity was detected in H9 HTLV IIIB cells, a clone chronically infected by HIV-1. Citreoviridin reduced p24 in the supernatant of H9 HTLV IIIB in a dose-dependent manner with a pharmacological selectivity index of 2.6. In C. albicans, the effects of the mold-derivative were evaluated on some parameters associated with pathogenicity and virulence: cellular proliferation, germ tube production, expression of heat shock mannoproteins, release of proteases and phospholipases. At a 12.5 microM dose, citreoviridin showed a marked inhibitory effect on all parameters analyzed. As regards the mechanism of action, it is possible to hypothesize that the effects of citreoviridin may be due to a reduction of protein synthesis, since it inhibited the replication of HIV-1 at post-integrational stages and reduced the intracellular RNA and protein content in C. albicans.

Expression of fibronectin and its receptor in some tumour cell lines and in HIV-1-infected cells

The aim of our study was to evaluate the levels of fibronectin (FN) and its classic receptor (FNR) in various transformed cells lines, especially of leukemic origin, and also the influence of HIV-1 replication on the expression of these proteins (in particular on H9-V cells, chronically infected with HIV-1, and acutely infected MT-4 cells). Monoclonal antibodies were used for indirect immunofluorescence tests; the fluorescein-conjugated recombinant p14, the product of the HIV gene tat, was used as a molecular probe. The results demonstrated a high variability of FN and FNR expression among the various cellular lines studied. Moreover, deficits of such adhesive proteins did not necessarily correlate with a severe reduction of the corresponding receptor. HIV-1 replication in MT-4 and H9-V cells increased the expression of FNR. This seems to correlate with p14-induced phenomena because pretreatment of H9-V cells with recombinant p14 showed an enhancing effect on the expression of this receptor.

Comparison of different in vitro tests for evaluating immune reactivity

We performed some in vitro tests for the detection of the immune state and compared the results. In particular we studied the production of various cytokines obtained by stimulating peripheral blood mononucleated cells (PBMC) with different inducers, using optimal and suboptimal doses. This was compared with the results of blastic transformation of lymphocytes, and with the evaluation of the capping effect of macrophages, and of the Multitest Merieux. The correlation between the different investigations was generally good. This permits a simplification of the study of immune reactivity, selecting some of the tests proposed. The use of suboptimal doses of inducers improves the evaluation of very moderate deficits and supplies an in vitro model for the study of immunomodulant drugs.

Long-term hormone replacement treatment in menopause: new choices, old apprehensions, recent findings

In recent years there has been an increase in the use of parenteral oestradiol as an alternative to the conventional oral preparations used in hormone replacement treatment (HRT) in menopause, such as conjugated equine oestrogens (CEE). The latter have been subject in the past to apprehensions, partly due to misunderstanding and oversimplification but also in relation to problems that have arisen during the history of HRT, for example the increase in endometrial cancer risk deriving from the use of non-progestogen-opposed treatment. However, confidence in long-term HRT comes from the epidemiological findings, which refer mainly to the use of oral CEE unopposed by progestogen: a reduced risk of osteoporotic fractures and of cardiovascular disease, and a very limited risk of breast cancer. Oral oestrogens produce marked hepatocellular effects. These effects are, on the whole, favourable from the point of view of cardiovascular risk. In addition, it cannot be excluded that some hepatocellular effects of oral oestrogen, for example increased sex hormone binding globulin levels and reduced circulating insulin-like growth factor I activity, offer protection to the breast. As progestogen supplementation is needed in non-hysterectomized women, priority should be given to preparations, such as progesterone or dydrogesterone, that feature good endometrial activity without opposing oestrogen hepatocellular effects.

Differential effects of oral conjugated estrogens and transdermal estradiol on insulin-like growth factor 1, growth hormone and sex hormone binding globulin serum levels

In postmenopausal women oral ethinylestradiol causes a reduction in circulating insulin-like growth factor 1 (IGF-1) and an increase in serum growth hormone levels. There are no data on the effect of conjugated estrogens, the preparation most often used in estrogen replacement treatment (ERT), on these parameters. We evaluated serum IGF-1 and growth hormone levels, together with the levels of sex hormone binding globulin (SHBG), an indicator of estrogen hepatocellular action, before and after 6 months of ERT in two comparable groups of postmenopausal women. Sixteen women were treated with oral conjugated estrogens, 0.625 mg/day, and 14 with transdermal estradiol, 0.05 mg/day. In the women treated with oral conjugated estrogens, an increase in SHBG (p < 0.001), a decrease in IGF-1 (p < 0.001) and an increase in growth hormone (p < 0.05) serum levels were observed. No such effects were seen with the use of transdermal estradiol, devoid of hepatocellular effects. Undoubtedly, oral conjugated estrogens, 0.625 mg/day, through a hepatocellular effect, cause marked modifications in the IGF-1/growth hormone axis, which may have clinical relevance. For instance, the decreased IGF-1 level, together with the increased level of SHBG, might provide some explanation of the favorable epidemiological data on breast cancer risk in women receiving oral conjugated estrogens.