Increased spontaneous secretion of interleukin 6 and tumor necrosis factor alpha by peripheral blood lymphocytes of human immunodeficiency virus-infected children

Diminished production of monocyte proinflammatory cytokines during human immunodeficiency virus viremia is mediated by type I interferons

The effect of human immunodeficiency virus (HIV) infection and high-level HIV replication on the function of monocytes was investigated. HIV-positive patients had elevated levels of spontaneous production of some or all of the monocyte proinflammatory cytokines measured (interleukin-1beta [IL-1beta], IL-6, and tumor necrosis factor alpha [TNF-alpha]) compared to uninfected controls. In patients on therapy with high frequencies of monocytes producing proinflammatory cytokines, this frequency was diminished in the context of viremia during an interruption of therapy. Diminished production of proinflammatory cytokines during viremia was restored by culture with autologous CD4(+) T cells or monocytes from an on-therapy time point or lipopolysaccharide (LPS). Microarray analysis demonstrated that diminished monocyte production of proinflammatory cytokines was correlated with elevated type I interferon-stimulated gene transcripts. The addition of exogenous alpha 2A interferon diminished the spontaneous production of IL-1beta, IL-6, and TNF-alpha but did not affect responses to LPS, recapitulating the changes observed for HIV-viremic patients. These results suggest that monocyte function is diminished during high-level HIV viremia and that this effect is mediated by chronic stimulation by type I interferons. This effect on monocytes during viremia may play a role in diminished innate or adaptive immune system functions in HIV-infected patients. In addition, the restoration of these functions may also play a role in some immune reconstitution syndromes observed during initiation of therapy.

Potential Mechanisms for Altered Iron Metabolism in Human Immunodeficiency Virus Disease

Recently, anemia associated with human immunodeficiency virus (HIV) disease has received more attention as our understanding of the significance of anemia in this population has grown and more emphasis is placed on the quality of life of people living with HIV/AIDS. Although the diagnosis and treatment of anemia in HIV disease has been discussed in great detail, the prevalence and pathophysiology of the two most common forms of anemia, iron deficiency anemia (IDA) and the anemia of chronic disease (ACD), have not received much attention despite the difficulty and importance of differentiating between these two anemias. In addition, little attention has been given to iron overload, which has serious implications in individuals with HIV disease. This article proposes a model of altered iron metabolism in HIV disease as a basis for explaining the pathophysiology and implications of IDA, ACD, and iron overload in this population. Implications for clinical practice and recommendations for future research are discussed.

Regulation of human immunodeficiency virus type 1 replication in human T lymphocytes by nitric oxide

Addition of nitric oxide (NO) donors to mitogen-activated human immunodeficiency virus type 1 (HIV-1)-infected peripheral blood mononuclear cultures produced a significant increase in virus replication, and this effect was not associated with a change in cell proliferation. This effect was only observed with T-tropic X4 or X4R5 virus but not with R5 virus. Moreover, HIV-1 replication in mitogen-stimulated cultures was partially prevented by the specific inhibitors of the inducible nitric oxide synthase (iNOS). NO donors also enhanced HIV-1 infection of the human T-cell lines, Jurkat and MT-2. We have also observed that NO leads to an enhancement of HIV-1 replication in resting human T cells transfected with a plasmid carrying the entire HIV-1 genome and activated with phorbol ester plus ionomycin. Thus, in those cultures NO donors strongly potentiated HIV-1 replication in a dose-dependent manner, up to levels comparable to those with tumor necrosis factor alpha (TNF-alpha) stimulation. Furthermore, iNOS inhibitors decreased HIV-1 replication in HIV-1-transfected T cells to levels similar to those obtained with neutralizing anti-TNF-alpha antibodies. Moreover, HIV-1 replication induced iNOS and TNF-alpha transcription in T cells and T-cell lines. Interestingly, NO donors also stimulated long terminal repeat (LTR)-driven transcription whereas iNOS inhibitors partially blocked TNF-alpha-induced LTR transcription. Therefore, our results suggest that NO is involved in HIV-1 replication, especially that induced by TNF-alpha.

Decreased CD95 expression on naive T cells from HIV-infected persons undergoing highly active anti-retroviral therapy (HAART) and the influence of IL-2 low dose administration. Irhan Study Group

The functional recovery of the immune system in HIV-infected persons receiving HAART and the role of adjuvant immune therapy are still matters of intensive investigation. We analysed the effects of HAART combined with cytokines in 22 naive asymptomatic individuals, randomized to receive HAART (n = 6), HAART plus a low dose (1000 000 U/daily) of rIL-2 (n = 8), and HAART plus rIL-2 after previous administration of granulocyte colony-stimulating factor (n = 8). After 3 months of therapy, increased CD4+ T cell counts and diminished viral loads were observed in all patients, independently of cytokine addition. A decreased expression of CD95 (Apo 1/Fas) was evident in all groups when compared with values before therapy. The percentages of peripheral blood mononuclear cells (PBMC) expressing CD95 after therapy decreased by 15%, 22% and 18% in the three treatment groups, respectively (P < 0.05). Analysis of PBMC subsets demonstrated that CD95 expression was significantly reduced on CD45RA+CD62L+ naive T cells (25.3%, 22.4%, and 18.6%, respectively; P < 0.05) in each group, after therapy. Accordingly, all patients showed a reduced rate of in vitro spontaneous apoptosis (P < 0.05). Another effect induced by HAART was a significant increase in IL-2Ralpha expression on total PBMC (P < 0.05), independently of cytokine addition. Altogether, our results suggest that very low dose administration of rIL-2 (1000 000 U/daily) may be not enough to induce a significant improvement in the immune system as regards HAART alone. The employment of higher doses of recombinant cytokines and/or different administration protocols in clinical trials might however contribute to ameliorate the immune reconstitution in patients undergoing HAART.

Energy balance, viral burden, insulin-like growth factor-1, interleukin-6 and growth impairment in children infected with human immunodeficiency virus

OBJECTIVE

To determine the relationship between energy metabolism and growth abnormalities in HIV-infected children and to assess clinical or laboratory characteristics which may be contributing factors to their growth impairment.

DESIGN

A comparative study.

METHODS

We measured energy intake by inpatient calorie count/outpatient 24 h food recalls, resting energy expenditure by indirect calorimetry, total energy expenditure by the doubly-labeled water technique, iron metabolism, protein metabolism, and lipid metabolism markers as well as CD4 count, viral load, insulin-like growth factor-1 (IGF-1), serum interleukin-6 (IL-6), and whole blood stimulated IL-6 levels in prepubertal congenitally HIV-infected children with normal and impaired growth patterns.

RESULTS AND CONCLUSIONS

Differences in energy expenditures were not found between normal and growth-impaired HIV-infected children. Energy intake but not energy expenditure was significantly reduced when HIV-infected children were compared to expected normal values for age and gender. Advanced HIV clinical disease, severe immune suppression, increased viral burden, increased IL-6 activity, decreased total serum protein, and decreased IGF-1 levels were more likely to be found in HIV-infected children with growth impairment in comparison with HIV-infected children with normal growth.

Interleukin-6 synthesis and IgE overproduction in children with perinatal human immunodeficiency virus-type 1 infection

BACKGROUND

Unbalanced interleukin network and elevated IL-6 synthesis are suggested mechanisms of immunoglobulin overproduction in children with perinatal human immunodeficiency virus-type 1 (HIV-1) infection.

OBJECTIVE

To investigate whether elevated IL-6 synthesis is a general mechanism of immunoglobulin overproduction in perinatal HIV-1 infection.

METHODS

In vitro spontaneous and phytohaemoagglutinin (PHA)-stimulated IL-6 and IL-2 synthesis, serum IgE, IgG, IgA, and IgM levels, CD4+ T-lymphocyte counts, and HIV-1 RNA copy numbers were cross-sectionally determined in 31 children with perinatal HIV-1 infection. Children with immunoglobulin z-scores in the highest quartile were defined as children with high immunoglobulin level. Relationships between interleukin synthesis, high immunoglobulin levels, and HIV-1 related disease were studied.

RESULTS

Children with high IgE levels had higher spontaneous IL-6 synthesis (1337 +/- 138 pg/mL) compared with those without high IgE levels (861 +/- 194 pg/mL; P < .001). By contrast, spontaneous IL-6 synthesis was similar in children with or without high IgG, IgA, or IgM levels. Decreased PHA-stimulated IL-2 synthesis, low CD4+ lymphocyte counts, elevated HIV-1 RNA copy numbers, and severe disease correlated with high IgE (but not IgG, IgA, and IgM) levels. IgG, IgA, and IgM levels correlated with each other, but not with IgE levels.

CONCLUSION

The increased IL-6 synthesis in HIV-1+ children may affect IgE rather than other immunoglobulin isotype levels. Overall results suggest that IgE and IgG, IgA, IgM overproduction have distinct underlying mechanisms.

Effects of human immunodeficiency virus and colony-stimulating factors on the production of interleukin 6 and tumor necrosis factor alpha by monocyte/macrophages

Patients infected with human immunodeficiency virus (HIV) frequently have increased production of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), and these cytokines may in turn contribute to the disease pathogenesis. It has been hypothesized that secretion of these cytokines by HIV-exposed mononuclear cells or HIV-infected monocyte/macrophages (M/Ms) is the principal source of their overproduction in HIV-infected patients, and the present study was undertaken to explore this issue. We observed that in the absence of endotoxin or cytokines, M/Ms productively infected by HIV do not produce detectable IL-6 or TNF-alpha. However, granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that enhances HIV replication in M/Ms and is frequently used to propagate monocytotropic strains of HIV, can induce the relatively long-term production of IL-6 (up to 47 U/ml) and TNF-alpha (up to 47 pg/ml) by M/Ms, even in the absence of HIV. Also, HIV induced production of a relatively small (< or = 9 U/ml) quantity of IL-6 in M/Ms stimulated with macrophage-colony stimulating factor (M-CSF). Finally, while highly concentrated HIV induced production of both cytokines by either M/Ms or peripheral blood mononuclear cells (PBMCs), this production was almost completely eliminated when care was taken to avoid contamination of HIV by endotoxin. These data suggest that the excess IL-6 and TNF-alpha in HIV-infected patients does not simply result from their production by HIV-infected M/Ms and that alternative mechanisms are involved in this process.