Type 1 and type 2 cytokine profiles in children exposed to or infected with vertically transmitted human immunodeficiency virus

Monocyte-derived interleukin-10 depresses the Bordetella pertussis- specific gamma interferon response in vaccinated infants

Antigen-specific gamma interferon (IFN-gamma) has been demonstrated to participate in protection against Bordetella pertussis infection. Circulating mononuclear cells from B. pertussis-infected and from pertussis-vaccinated infants secrete high amounts of IFN-gamma after in vitro stimulation by B. pertussis antigens, but with a large variation in the secreted IFN-gamma levels between individuals. We show here that the inhibition of the specific IFN-gamma response can be at least partially attributed to IL-10 secretion by monocytes. This IL-10 secretion was not associated with polymorphisms at positions -1082, -819, and -592 of the IL-10 gene promoter, suggesting that other genetic or environmental factors affect IL-10 expression and secretion.

Microbial translocation, the innate cytokine response, and HIV-1 disease progression in Africa

Reports from the United States have demonstrated that elevated markers of microbial translocation from the gut may be found in chronic and advanced HIV-1 infection and are associated with an increase in immune activation. However, this phenomenon's role in HIV-1 disease in Africa is unknown. This study examined the longitudinal relationship between microbial translocation and circulating inflammatory cytokine responses in a cohort of people with varying rates of HIV-1 disease progression in Rakai, Uganda. Multiple markers for microbial translocation (lipopolysaccharide, endotoxin antibody, and sCD14) did not change significantly during HIV-1 disease progression. Moreover, circulating immunoreactive cytokine levels either decreased or remained virtually unchanged throughout disease progression. These data suggest that microbial translocation and its subsequent inflammatory immune response do not have a causal relationship with HIV-1 disease progression in Africa.

Interleukin-12 is necessary for the priming of CD4+ T cells required during the elicitation of HIV-1 gp120-specific cytotoxic T-lymphocyte function

The mechanism of the T-cell response and cytokine induction to restrict human immunodeficiency virus 1 (HIV-1) infection is not clear. During early infection, HIV-infected individuals have a high frequency of virus-specific cytotoxic T lymphocytes (CTLs) that effectively reduces the viral load. However, the CTLs are unable to clear the virus at later stages of infection, leading to disease progression. Dysregulation of cytokines like interleukin-12 (IL-12) and interferon-gamma (IFN-gamma) as a result of the interaction of HIV-1-specific T cells with antigen-presenting cells is one of the possible causes of CTL dysfunction. Secretion of IL-12 is reduced with the progression of HIV infection, correlating with impaired CTL function; however, the role of IL-12 in CTL regulation awaits elucidation. Here, we have studied the role of IL-12 in CTL dysfunction by using DNA immunization of wild-type (WT) and IL-12-deficient mice with HIV-1 gp120 complementary DNA. It was observed that the CTL response in IL-12-deficient mice was significantly less than that in WT mice. Our results further demonstrated that coimmunization with IL-12 vector restored the impaired CTL response in IL-12-deficient mice. However, immunization with IL-12 vector failed to rescue the CTL response in IFN-gamma deficient mice, suggesting that the CTL-promoting function of IL-12 is IFN-gamma-mediated. Our data suggest a phase-specific role of IL-12 in the CTL response, specifically in the priming of CD4+ T cells that provide help to CD8+ T cells. Our results also suggest that IL-12 is vital for the priming of antigen-specific T cells and plays an essential role in IFN-gamma induction in T cells.

The relevance of cytokines for development of protective immunity and rational design of vaccines

Cytokines are key regulators of the immune system that shape innate and adaptive immune responses. An adequate balance of the cytokine environment is critical to achieve protective immunity and to avoid immunopathology. Present knowledge allows a deeper understanding of the cytokine network and their sometimes conflicting roles in the development of immune responses, as well as their relevance in the establishment and maintenance of immunological memory. New insights have been gained into the role of different T cell subsets for protection against infection or tumor growth. The incorporation of cytokines as molecular adjuvants in vaccines has been attempted to strengthen vaccine-induced immune responses, and as a rational approach to modulate cytokine milieu in vivo and tailor host immunity for specific situations. These approaches have been tried in experimental models and veterinary species, and a few of them have entered into clinical trials. However, manipulating the cytokine network to modulate immune responses is not a simple task, because cytokine functions are complex and the final effects on the immune response will depend on timing and length of exposure, cell(s) targeted and other cytokines present in the same microenvironment. Here, we will review our present understanding on the role of cytokines in the development of effector and memory T cell responses. Also the potential use of cytokines as molecular adjuvant for vaccines against infectious diseases and cancer will be revised.

IL-2 and IL-10 serum levels in HIV-1-infected patients with or without active antiretroviral therapy

We analyzed IL-2 and IL-10 serum levels in 26 HIV-1-infected patients naive of antiretroviral treatment and in 34 patients receiving highly active antiretroviral therapy (HAART). All patients without treatment were asymptomatic. When they were stratified according to levels of CD4+ T cells, IL-2 levels were significantly increased in patients with > or =200 CD4+/microl and IL-10 levels were significantly increased in patients with <200 CD4+/microl compared to controls. A significant negative correlation was observed between IL10 levels and CD4+ T-cell counts. No correlation was observed between IL-2 and IL-10 levels and viral load due to the wide range of variability in the number of HIV copies/ml present in the different patients. However, IL-2 levels were higher in patients with high viral load than in patients with low viral load. In patients with HAART, IL-2 and IL-10 levels were similar to the control group and no differences were detected respecting CD4+ T cells counts and viral load. Our findings show that the modifications in IL-2 and IL-10 serum levels in HIV-1-infected patients naive of antiretroviral treatment are associated with the progression of immunological damage. Furthermore, they show a dysbalance of type-1/type-2 cytokines with an involvement of type-2 cytokines in later stages of HIV infection. Cytokine dysregulation can be reversed by HAART in the context of immune restoration and viral suppression.

Phase I/II trial of intravenous recombinant interleukin-2 in HIV-infected children

OBJECTIVES

To define the tolerated dose of recombinant interleukin-2 (rIL-2) in HIV-infected children (part A), and to determine the safety and immunologic effects of the tolerated rIL-2 dose in a cohort of HIV-infected children (part B).

DESIGN

Open-label, dose-escalation.

SETTING

Multiple center study.

SUBJECTS

Twenty HIV-infected children, aged 3-12 years.

INTERVENTION

In part A six subjects received 1 x 10(6) IU/m2 and four subjects received 4 x 10(6) IU/m2 rIL-2 by continuous intravenous infusion for 5 days every 8 weeks for three cycles. In part B 10 different subjects received 1 x 10(6) IU/m2 for 5 days every 8 weeks for six cycles.

MAIN OUTCOME MEASURES

Toxicity, CD4 cell count and percentage, and viral load.

RESULTS

The tolerated dose of rIL-2 was 1 x 10(6) IU/m2. The most common side effects were fever and vomiting. Of 10 subjects enrolled in part B of the study, five discontinued rIL-2 therapy for a variety of reasons, most related to administration of study drug. Comparable rises in CD4 cell count and percentage were observed in each of the treatment arms. Six cycles of rIL-2 therapy did not appear to be better than three cycles with respect to improvement of CD4 parameters. Transient rises in plasma HIV-1 RNA levels were detected in some subjects.

CONCLUSIONS

These results suggest that rIL-2 therapy can raise CD4 cell counts and percentages in some HIV-infected children, although a high proportion of HIV-infected children may have to discontinue intravenous therapy because of drug- or administration-related toxicity. Controlled trials of rIL-2 in this patient population are warranted.

TH1 and TH2 cytokine mRNA and protein levels in human immunodeficiency virus (HIV)-seropositive and HIV-seronegative youths

The roles of cytokines in the progression of human immunodeficiency virus (HIV)-associated disease are controversial. The patterns of innate cytokine production have been postulated to shift from TH1- to TH2-type cytokines with the progression of HIV-associated disease. Although there have been studies of cytokines in children and adults, no data are available on cytokine production in healthy or HIV-infected adolescents. We analyzed and characterized cytokine mRNA and protein levels for gamma interferon, interleukin 2 (IL-2), IL-4, and tumor necrosis factor alpha and protein levels of IL-6 in both stimulated and unstimulated peripheral blood mononuclear cells obtained from a large longitudinal, observational cohort study of HIV-seropositive and -seronegative adolescents. We correlated cytokine results with viral load and CD4(+)-T-cell counts as critical markers of disease progression in HIV-infected adolescents. These data were used to examine hypotheses related to the TH1-to-TH2 cytokine shift in a sample of HIV-infected adolescents. Five hundred twenty subjects participating in the REACH (Reaching for Excellence in Adolescent Care and Health) Project of the Adolescent Medicine HIV/AIDS Research Network contributed blood samples. Samples selected for the cross-sectional data set analyzed had to meet selection criteria developed to minimize the potential confounding effects of acute intercurrent illnesses or infections, recent vaccination for hepatitis, and altered hormone status and to optimize congruence of cytokine measurements with assays of viral load and CD4(+)-T-cell counts. Group differences in the proportions of subjects with detectable levels of each cytokine marker were compared. In the subset of subjects with detectable cytokine values, differences in detected values were compared across subgroups defined by HIV serostatus and among HIV-seropositive subjects by three viral load classifications. The study sample was 65% HIV seropositive, 71% African-American, and 75% female with a mean age of 17.4 years. HIV-seropositive subjects were relatively healthy with mean and median CD4(+)-T-cell counts of 534 and 499 cells/mm(3), respectively. Only 8.1% of subjects had CD4(+)-T-cell counts below 200 cells/mm(3), and 25% had viral loads that were below the threshold of detection (<400 copies/ml). Detailed analyses of these data indicate that there were no differences in cytokines detected in HIV-seropositive and HIV-seronegative adolescents, and there was no apparent relationship between the cytokine measurements and the viral load or CD4(+)-T-cell categorization, the parameters selected as markers of HIV-associated disease status. These adolescents, including the HIV-seropositive subjects, were relatively healthy, and the HIV-infected subjects were at an early stage in the course of their HIV-associated disease. On the basis of our data, we conclude that, early in the course of HIV-associated disease in adolescents, there are no detectable shifts from TH1 to TH2 cytokine production.

Magnitude of IFN-gamma production in HIV-1-infected children is associated with virus suppression

BACKGROUND

Little is known about the cytokine production by peripheral blood cells of pediatric patients who have suppressed HIV-1 replication after highly active antiretroviral therapy (HAART).

OBJECTIVE

We sought to determine the effect of HAART on the production of T(H)1 and T(H)2 cytokines by HIV-infected children who have suppressed HIV replication.

METHODS

At 3- to 6-month intervals over a 5-year period, CD4(+) T cells were enumerated, plasma HIV-1 RNA was measured, and levels of cytokine production by whole blood cultures were determined in 21 HIV-1-infected children.

RESULTS

Ten patients achieved an HIV-1 RNA level of less than 3000 copies/mL of plasma and maintained that level for at least 15 months (virus-suppressed [VS] group). Eleven patients had a mean HIV-1 RNA level of greater than 10(4) copies/mL of plasma and a mean CD4(+) T-cell count of less than 500/microL of blood (active infection group). The median levels of anti-CD3-induced IL-2, IFN-gamma, and IL-10 in the active infection group were significantly lower than those in the VS group after suppression of the virus. The median slope of IFN-gamma production by means of PHA-stimulated culture after achieving VS status (4.04) was significantly higher than the level before VS status (-1.31, P =.004). The difference in the median slopes for IL-10 production by anti-CD3-stimulated cultures before (0.21) and after (-0.16) achieving VS status was statistically different (P =.027).

CONCLUSION

The immune restoration of HIV-1-infected children receiving HAART might be related to an increase in IFN-gamma production and a decrease in the rate of IL-10 production after virus suppression.

Interleukin (IL)-4 inhibits phorbol-ester induced HIV-1 expression in chronically infected U1 cells independently from the autocrine effect of endogenous tumour necrosis factor-alpha, IL-1beta, and IL-1 receptor antagonist

The anti-inflammatory cytokine interleukin 4 (IL-4) has shown both inductive and inhibitory effects on the replication of the human immunodeficiency virus type 1 (HIV-1) in primary CD4+ T cells and mononuclear phagocytes. In this study, IL-4 did not induce virus production, but inhibited phorbol esters (PMA)-stimulated HIV expression in chronically infected promonocytic U1 cells. This effect, however, was not accounted for by a decreased secretion of endogenous TNF-alpha induced by phorbol myristate acetate (PMA). We also observed that PMA upregulated the production of both IL-1beta and of IL-1 receptor antagonist (IL-1ra). IL-4 inhibited the secretion of IL-1beta and strongly increased that of IL-1ra; however, these effects were not responsible of IL-4-mediated inhibition of PMA-induced HIV expression since anti-IL-1ra antibodies did not revert IL-4 mediated suppression. U1 cells were transiently transfected with both wild-type (WT) long terminal repeat (LTR) constructs, or with LTR plasmids containing deletions of either the NF-kappaB or the Sp-1 binding sites. IL-4 inhibited LTR-driven transcription triggered by PMA stimulation of U1 cells, and this effect was dependent upon intact NF-kappaB but not Sp-1 binding sites. Thus, IL-4 may favour a state of microbiological quiescence in infected monocytic cells bypassing the induction of HIV expression mediated by pro-inflammatory cytokines.

Interferon-gamma and interleukin-10 production among HIV-1-infected and uninfected infants of HIV-1-infected mothers

Immunologic consequences of exposure to HIV-1 in utero are still poorly understood. This study investigates relationships between type-1 [interferon-gamma (IFN-gamma)] and type-2 (IL-10) cytokine production and maternal-infant HIV-1 transmission. Cord blood leukocytes from deliveries of 71 HIV-1-infected and 11 uninfected mothers were tested for in vitro IFN-gamma and IL-10 production after phytohemagglutinin (PHA) stimulation. The infants of these HIV-1-infected mothers were followed prospectively after birth to determine HIV vertical transmission, and IFN-gamma and IL-10 production was measured again at 6 mo. Median PHA-stimulated IFN-gamma production was 210 pg/mL in cord blood cells from infected and 73 pg/mL from uninfected mothers (p = 0.12), and median PHA-stimulated IL-10 production was 491 pg/mL in cord blood cells from infected and 161 pg/mL from uninfected mothers (p = 0.004). PHA-stimulated IFN-gamma and IL-10 production alone were not significantly associated with transmission, but relationships between the two cytokines differed among infected and uninfected infants of HIV-1-infected mothers. PHA-stimulated IFN-gamma and IL-10 production was positively correlated among infected (r = 0.7, p = 0.12 in cord blood and r = 0.66, p = 0.03 at 6 mo) but not uninfected infants, and stronger relative production of IFN-gamma to IL-10 was observed among exposed uninfected than among infected infants (p = 0.04). Exposure in utero to HIV-1 may augment production of IL-10 detectable in fetal cord blood. Stronger relative production of IFN-gamma to IL-10 in cord blood cells from infants of HIV-1-infected mothers may be associated with protection against perinatal HIV infection.

Enhanced interferon-gamma by CD8+ CD28- lymphocytes from HIV+ patients

Flow cytometric analysis of T cells from HIV+ and normal individuals activated for 15 hr showed that the percentage of cells producing interferon-gamma (INFgamma) was enhanced approximately threefold (39 compared to 14%) in the HIV+ CD8+ population. Activation modes, other than anti-CD3 with PMA, were ineffective, and in no case did the percentage of HIV+ CD4+ T cells show increased INFgamma production over controls. Enhanced INFgamma production was not induced by either anti-CD3 or PMA alone, or anti-CD3 or ConA with anti-CD28, or enhanced by N-acetylcysteine. In contrast to INFgamma production, the percentage of CD4+ T cells producing interleukin-2 (Il-2) greatly exceeded that of the CD8+ T cells. The results from flow cytometry analyses of HIV+ CD8+ T cells was supported by quantitative analysis of INFgamma mRNA (by PCR) and INFgamma secretion by ELISA. These methods showed a sixfold and three- to fivefold increase, respectively, on a per cell basis. As HIV infection progresses, as shown by loss of CD4+ T cells, the proportion of CD8+ CD28- T cells increases, and it is this T cell subset that is responsible for 80% or more of the enhanced INFgamma production. The enhanced INFgamma in HIV+ patients derives from two factors: the increase in CD8+ CD28- cells to 70% and the percentage producing INFgamma (60%, compared to 21% for CD8+ CD28+ cells). Our findings of a substantial increase in INFgamma production in HIV infection arising from the increased number of CD8+ CD28- T cells are compatible with clinical studies which show elevated INFgamma in HIV+ serum and INFgamma producing CD8+ T cells dominating HIV+ lymph nodes. We also found a significantly decreased proliferative response of the HIV+-derived CD8+ T cell fraction with coactivator anti-CD-28, in contrast to PMA (with anti-CD3), which is probably a reflection of the diminished population of CD8+ CD28+ T cells in HIV+ donors compared to normal donors (30.7 compared to 67.9%).

Synthesis of IFN-gamma by CD8(+) T cells is preserved in HIV-infected women with HPV-related cervical squamous intraepithelial lesions

OBJECTIVE

The aim of this study was to investigate whether coinfection with HIV affects the synthesis of Th1 and Th2 cytokines by peripheral blood T cells of women infected with human papillomavirus (HPV).

METHODS

Cervical swabs and peripheral blood were obtained from women referred for colposcopy. HPV DNA by Digene's hybrid capture assay, HIV RNA by Roche's Amplicor assay, and cytokine synthesis of T-cell subsets by flow cytometry were assessed. HPV-associated cervical and HIV-associated immune deficiency diseases were staged using the Bethesda System and the Centers for Disease Control criteria, respectively.

RESULTS

Patients with HIV and/or HPV infections had lower percentages of IL-2(+) and higher percentages of IL-10(+) T cells than healthy women. Furthermore, women with both virus infections (HIV(+)/HPV(+)) had significantly fewer IL-2(+) CD4(+), IFN-gamma(+) CD4(+), and TNF-alpha(+) CD4(+) T cells than women with HPV infection alone (HPV(+)). Whereas HIV(+) and healthy women had similar numbers of IFN-gamma(+) CD8(+) T cells, HPV(+) women had significantly fewer IFN-gamma(+) CD8(+) T cells than healthy women.

CONCLUSION

HIV infection adversely affects the synthesis of Th1 cytokines by CD4(+), but not IFN-gamma synthesis by CD8(+) T cells of women with active HPV infection. The increase in IFNgamma(+) CD8(+) T cells, a phenotype consistent with cytotoxic T lymphocytes, may account for the stable HIV disease of the women studied. However, the increase in IFN-gamma(+) CD8(+) T cells is less likely to be HPV-specific as there was a higher incidence of HPV-related cervical SIL in HIV(+)/HPV(+) women compared with HPV(+) women.

HIV infection and AIDS

The entry of one HIV virion into a human being has the potential to cause death by the inexorable replication of the virus within the principal T lymphocyte, the CD4+ T cell. Although combination antiretroviral therapy, particularly therapy with protease inhibitors, decreases the viral burden to very low, even undetectable, levels, sequestration of the virus in privileged sites, including a long-lived CD4+ T cell, has frustrated efforts at eradication of HIV. Activation of the immune system, therefore, appears essential before this infection can be conquered. Powerful vaccines capable of preventing infection remain the hope of the world.

Cytokine production in cell culture by peripheral blood mononuclear cells from immunocompetent hosts

The production of interleukin 2 (IL-2) gamma interferon, IL-4, tumor necrosis factor alpha (TNF-alpha), TNF-beta, IL-5, and IL-10 in vitro by peripheral blood mononuclear cells cultured from healthy immunocompetent subjects after mitogen stimulation was determined. The mitogens used were concanavalin A, phytohemagglutinin, pokeweed mitogen, and Staphylococcus aureus Cowen. The results obtained provide a normal range for the production of these cytokines under specified conditions in vitro.