The effect of cytokines and pharmacologic agents on chronic HIV infection

Men with HIV have increased alveolar bone loss

BACKGROUND

Periodontal health in men with HIV remains understudied, despite suggestions of associations between HIV infection and gingival pocketing, periodontal attachment loss, and gingival inflammation. As antiretroviral therapy (ART) has improved the quality of life for people living with HIV (PLWH), aging-related risk factors and comorbidities, including periodontitis, have emerged. This study aims to assess alveolar bone height, gingival crevicular fluid (GCF) cytokines, and periodontal disease activity in men with and without HIV.

METHODS

Ninety-three men (50 HIV+, 43 HIV-) aged 35-70 years were recruited from Columbia University Irving Medical Center clinics. Periodontal examination, GCF collection, and intraoral radiographs were collected. Statistical analysis was conducted with t-tests for continuous variables and chi-squared tests for categorical variables.

RESULTS

While no significant differences were observed in bleeding on probing, clinical attachment loss and pocket depths, men with HIV exhibited significantly greater alveolar crestal height on radiographs compared to men without HIV (HIV + 3.41+/-1.35 mm, HIV- 2.64+/-1.01 mm; p = 0.004), reflecting greater alveolar bone loss.

CONCLUSIONS

Men living with HIV demonstrate increased alveolar bone loss compared to those without HIV, possibly mediated by elevated IL6 levels. These results underscore the importance of comprehensive oral health management in PLWH and highlight the need for further research understanding the mechanisms linking HIV infection, cytokine dysregulation, and periodontal health.

Men with HIV Have Increased Alveolar Bone Loss

Background

Periodontal health in men with HIV remains understudied, despite suggestions of associations between HIV infection and gingival pocketing, periodontal attachment loss, and gingival inflammation. As antiretroviral therapy (ART) has improved the quality of life for people living with HIV (PLWH), aging-related risk factors and comorbidities, including periodontitis, have emerged. This study aims to assess alveolar bone height, gingival crevicular fluid (GCF) cytokines, and periodontal disease activity in men with and without HIV.

Methods

Ninety-three men (50 HIV+, 43 HIV‒) aged 35-70 years were recruited from Columbia University Irving Medical Center clinics. Periodontal examination, GCF collection, and intraoral radiographs were conducted.

Results

While no significant differences were observed in bleeding on probing, clinical attachment loss and pocket depths, men with HIV exhibited significantly greater alveolar crestal height on radiographs compared to men without HIV (HIV + 3.41+/-1.35 mm, HIV- 2.64+/-1.01 mm; p = 0.004), reflecting greater alveolar bone loss. GCF IL6 levels showed a trend towards elevation in men with HIV (HIV + 0.349+/-0.407 pg/ml, HIV- 0.220+/-0.228 pg/ml; p = 0.059).

Conclusions

Men with HIV demonstrate increased alveolar bone loss compared to those without HIV, possibly mediated by elevated IL6 levels. These results underscore the importance of comprehensive oral health management in PLWH and highlight the need for further research understanding the mechanisms linking HIV infection, cytokine dysregulation, and periodontal health.

The cytokine/chemokine response in Leishmania/HIV infection and co-infection

HIV infection progressively weakens the immune system by infecting and destroying cells involved in host defense. Viral infection symptoms are generated and aggravated as immunosuppression progresses, triggered by the presence of opportunistic infections: among these is leishmaniasis, a disease caused by the intracellular parasite Leishmania. The incidence of this co-infection is growing progressively due to the geographic distribution overlap. Both pathogens infect monocytes/macrophages and dendritic cells, although they can also modulate the activity of other cells without co-infecting, such as T and B lymphocytes. Leishmania/HIV co-infection could be described as a system comprising modulations of cell surface molecule expression, production of soluble factors, and intracellular death activities, leading ultimately to the potentiation of infectivity, replication, and spread of both pathogens. This review describes the cytokine/chemokine response in Leishmania/HIV infection and co-infection, discussing how these molecules modulate the course of the disease and analyzing the therapeutic potential of targeting this network.

CD8+ Lymphocytes from Healthy Blood Donors Secrete Antiviral Levels of Interferon-Alpha

The adaptive immune response to viral infections features the antigen-driven expansion of CD8+ T cells. These cells are widely recognized for their cytolytic activity that is mediated through the secretion of cytokines such as perforin and granzymes. Less appreciated is their ability to secrete soluble factors that restrict virus replication without killing the infected cells. In this study we measured the ability of primary anti-CD3/28-stimulated CD8+ T cells from healthy blood donors to secrete interferon-alpha. Supernatants collected from CD8+ T cell cultures were screened for their ability to suppress HIV-1 replication in vitro and their interferon-alpha concentrations were measured by ELISA. Interferon-alpha concentrations in the CD8+ T cell culture supernatants ranged from undetectable to 28.6 pg/mL. The anti-HIV-1 activity of the cell culture supernatants was observed to be dependent on the presence of interferon-alpha. Appreciable increases in the expression levels of type 1 interferon transcripts were observed following T cell receptor stimulation, suggesting that the secretion of interferon-alpha by CD8+ T cells is an antigen-driven response. In 42-plex cytokine assays, the cultures containing interferon-alpha were also found to contain elevated levels of GM-CSF, IL-10, IL-13, and TNF-alpha. Together, these results demonstrate that the secretion of anti-viral levels of interferon-alpha is a common function of CD8+ T cells. Furthermore, this CD8+ T cell function likely plays broader roles in health and disease.

β-Catenin Regulates Wound Healing and IL-6 Expression in Activated Human Astrocytes

Reactive astrogliosis is prominent in most neurodegenerative disorders and is often associated with neuroinflammation. The molecular mechanisms regulating astrocyte-linked neuropathogenesis during injury, aging and human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) are not fully understood. In this study, we investigated the implications of the wingless type (Wnt)/β-catenin signaling pathway in regulating astrocyte function during gliosis. First, we identified that HIV-associated inflammatory cytokines, interleukin (IL)-1β and tumor necrosis factor (TNF)-α induced mediators of the Wnt/β-catenin pathway including β-catenin and lymphoid enhancer-binding factor (LEF)-1 expression in astrocytes. Next, we investigated the regulatory role of β-catenin on primary aspects of reactive astrogliosis, including proliferation, migration and proinflammatory responses, such as IL-6. Knockdown of β-catenin impaired astrocyte proliferation and migration as shown by reduced cyclin-D1 levels, bromodeoxyuridine incorporation and wound healing. HIV-associated cytokines, IL-1β alone and in combination with TNF-α, strongly induced the expression of proinflammatory cytokines including C-C motif chemokine ligand (CCL)2, C-X-C motif chemokine ligand (CXCL)8 and IL-6; however, only IL-6 levels were regulated by β-catenin as demonstrated by knockdown and pharmacological stabilization. In this context, IL-6 levels were negatively regulated by β-catenin. To better understand this relationship, we examined the crossroads between β-catenin and nuclear factor (NF)-κB pathways. While NF-κB expression was significantly increased by IL-1β and TNF-α, NF-κB levels were not affected by β-catenin knockdown. IL-1β treatment significantly increased glycogen synthase kinase (GSK)-3β phosphorylation, which inhibits β-catenin degradation. Further, pharmacological inhibition of GSK-3β increased nuclear translocation of both β-catenin and NF-κB p65 into the nucleus in the absence of any other inflammatory stimuli. HIV+ human astrocytes show increased IL-6, β-catenin and NF-κB expression levels and are interconnected by regulatory associations during HAND. In summary, our study demonstrates that HIV-associated inflammation increases β-catenin pathway mediators to augment activated astrocyte responses including migration and proliferation, while mitigating IL-6 expression. These findings suggest that β-catenin plays an anti-inflammatory role in activated human astrocytes during neuroinflammatory pathologies, such as HAND.

Interleukin-18 in Health and Disease

Interleukin (IL)-18 was originally discovered as a factor that enhanced IFN-γ production from anti-CD3-stimulated Th1 cells, especially in the presence of IL-12. Upon stimulation with Ag plus IL-12, naïve T cells develop into IL-18 receptor (IL-18R) expressing Th1 cells, which increase IFN-γ production in response to IL-18 stimulation. Therefore, IL-12 is a commitment factor that induces the development of Th1 cells. In contrast, IL-18 is a proinflammatory cytokine that facilitates type 1 responses. However, IL-18 without IL-12 but with IL-2, stimulates NK cells, CD4⁺ NKT cells, and established Th1 cells, to produce IL-3, IL-9, and IL-13. Furthermore, together with IL-3, IL-18 stimulates mast cells and basophils to produce IL-4, IL-13, and chemical mediators such as histamine. Therefore, IL-18 is a cytokine that stimulates various cell types and has pleiotropic functions. IL-18 is a member of the IL-1 family of cytokines. IL-18 demonstrates a unique function by binding to a specific receptor expressed on various types of cells. In this review article, we will focus on the unique features of IL-18 in health and disease in experimental animals and humans.

Clastogenic Factors as Potential Biomarkers of Increased Superoxide Production

The formation of clastogenic factors (CF) and their damaging effects are mediated by superoxide, since superoxide dismutase is regularly protective. CF are produced via superoxide and stimulate the production of superoxide by monocytes and neutrophils. This results in a selfsustaining and longlasting process of clastogenesis, which may exceed the DNA repair system and ultimately lead to cancer (Emerit, 1994). An increased cancer risk is indeed observed in conditions accompanied by CF formation. These include irradiated persons, patients with chronic inflammatory diseases, HIV-infected persons and the chromosomal breakage syndromes ataxia telangiectasia, Bloom's syndrome and Fanconi's anemia. Biochemical analysis has identified lipid peroxidation products, arachidonic acid metabolites, nucleotides of inosine and cytokines, in particular tumor necrosis factor alpha, as the clastogenic and also superoxide stimulating components of CF. Due to their chromosome damaging effects, these oxidants can be detected with classical cytogenetic techniques. Their synergistic action renders the CF-test particularly sensitive for the detection of a pro-oxidant state. Correlations were observed between CF and other biomarkers of oxidative stress such as decreases in total plasma thiols or increases in TBARS or chemiluminescence. Correlations between CF and disease activity, between CF and radiation exposure, suggest the study of CF for monitoring these conditions. CF may also be useful as biochemical markers and intermediate endpoints for the evaluation of promising antioxidant drugs.

CF formation represents a link between chronic inflammation and carcinogenesis. Prophylactic use of superoxide scavengers as anticarcinogens is therefore suggested.

T Cell Costimulation by Derivatives of Benzoic Acid

A number of analogues of benzoic acid were evaluated in a T cell costimulation assay. One compound, the sodium salt of 2-chloro-5-nitrobenzoic acid (CNBA-Na) was chosen for further study and was found to be a potent costimulator of anti-CD3-induced proliferation of both H9 lymphoblastoid cells ( P<0.001) and human peripheral blood mononuclear cells ( P=0.001) in a dose-dependent manner. The costimulatory effect of CNBA-Na on CD3-triggered DNA synthesis did not enhance human immunodeficiency virus replication in infected cells. Studies with blocking monoclonal antibodies against B7-1 or B7-2 indicated that the immunopotentiatory effect of CNBA-Na required a macromolecular interaction between CD28 (a costimulatory receptor on T cells) and its counter receptor B7 expressed on antigen-presenting cells. The discovery that this low molecular weight compound causes T cell proliferation highlights a potentially novel therapeutic approach to immunodeficiency diseases.

IL-8 Alterations in HIV-1 Infected Children With Disease Progression

Disease progression in HIV-1 infected children is faster than in adults. Less than 5% of the infected children maintain stable CD4 counts beyond 7 years of infection and are termed long-term nonprogressors (LTNPs). Delineating the host immune response in antiretroviral naïve (ART) and treated HIV-1 infected children at different disease stages will help in understanding the immunopathogenesis of the disease.A total of 79 asymptomatic, perinatally HIV-1 infected children (50 ART naïve and 29 ART treated) and 8 seronegative donors were recruited in this study. T- and B-cell activation PCR arrays were performed from the cDNA, using total RNA extracted from the peripheral blood mononuclear cells (PBMCs) of 14 HIV-1 infected children at different stages of the disease. The differentially expressed genes were identified. Quantitative RT-PCR was performed for the (interleukin-8) IL-8 gene and its transcriptional mediators, that is, SHP2, GRB2, and IL-8R (IL-8 receptor/CXCR1). Plasma levels of IL-8 were measured by flow cytometry.Gene array data revealed a higher expression of IL-8 in the ART naïve HIV-1 infected progressors and in ART nonresponders than LTNPs and ART responders, respectively. Quantitative RT-PCR analysis demonstrated a significant higher expression of IL-8 (P < 0.001), its receptor CXCR1 (P = 0.03) and the upstream signaling molecule SHP2 (P = 0.04) in the progressors versus LTNPs. Plasma levels of IL-8 were significantly higher in progressors versus LTNPs (P < 0.001), and ART nonresponders versus ART responders (P < 0.001). A significant negative correlation of plasma levels of IL-8 with CD4 counts (cells/μL) was observed in HIV-1 infected ART naïve subjects (r = -0.488; P < 0.001), while the IL-8 levels positively correlated with viral load in the ART treated children (r = 0.5494; P < 0.001). ART naïve progressors on follow up demonstrated a significant reduction in the mRNA expression (P = 0.05) and plasma levels of IL-8 (P = 0.05) post 6 months of ART initiation suggesting the beneficial role of ART therapy in reducing inflammation in infected children.Our data suggest that IL-8 may serve as a potential prognostic marker in adjunct with CD4 counts to monitor disease progression in the HIV-1 infected children and the efficacy of ART.

Heme oxygenase-1 dysregulation in the brain: implications for HIV-associated neurocognitive disorders

Heme oxygenase-1 (HO-1) is a highly inducible and ubiquitous cellular enzyme that subserves cytoprotective responses to toxic insults, including inflammation and oxidative stress. In neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease and multiple sclerosis, HO-1 expression is increased, presumably reflecting an endogenous neuroprotective response against ongoing cellular injury. In contrast, we have found that in human immunodeficiency virus (HIV) infection of the brain, which is also associated with inflammation, oxidative stress and neurodegeneration, HO-1 expression is decreased, likely reflecting a unique role for HO-1 deficiency in neurodegeneration pathways activated by HIV infection. We have also shown that HO-1 expression is significantly suppressed by HIV replication in cultured macrophages which represent the primary cellular reservoir for HIV in the brain. HO-1 deficiency is associated with release of neurotoxic levels of glutamate from both HIV-infected and immune-activated macrophages; this glutamate-mediated neurotoxicity is suppressed by pharmacological induction of HO-1 expression in the macrophages. Thus, HO-1 induction could be a therapeutic strategy for neuroprotection against HIV infection and other neuroinflammatory brain diseases. Here, we review various stimuli and signaling pathways regulating HO-1 expression in macrophages, which could promote neuronal survival through HO-1-modulation of endogenous antioxidant and immune modulatory pathways, thus limiting the oxidative stress that can promote HIV disease progression in the CNS. The use of pharmacological inducers of endogenous HO-1 expression as potential adjunctive neuroprotective therapeutics in HIV infection is also discussed.

Plasma levels of Transforming Growth Factor Beta in HIV-1 patients with oral candidiasis

BACKGROUND AND PURPOSE

TGF-β is a potent regulator and suppressor of the immune system and overproduction of this cytokine may contribute to immunosuppression in HIV-infected patients. Increasing population of immunosuppressed patients has resulted in increasingly frequent of fungal infections, including oral candidiasis. The aim of this study was to evaluate the plasma levels of TGF-β under in vivo conditions.

MATERIALS AND METHODS

Seventy- two samples were obtained from the oral cavities of HIV-positive Iranian patients and cultured on Sabouraud's dextrose agar and CHROMagar. Also blood samples were obtained to assess TGF-β levels using ELISA technique.

RESULTS

Thirty-three out of 72 oral samples yielded candida isolates, Candida albicans in 14 and non-albicans candida in 19.Fungal infection decreased significantly more TGF-β level than non-fungal infection also HIV negative were significantly more TGF-β than HIV positive.

CONCLUSION

Our findings suggest a significant interaction between fungal infection and HIV on expression of Transforming Growth Factor Beta.

Retrocyclin RC-101 blocks HIV-1 transmission across cervical mucosa in an organ culture

BACKGROUND

Cervical tissue-based organ cultures have been used successfully to evaluate microbicides for toxicity and antiviral activity. The antimicrobial peptide retrocyclin RC-101 has been shown to have potent anti-HIV activity in cell culture.

OBJECTIVE

To evaluate RC-101 in organ culture for toxicity and its ability to block HIV-1 transmission across cervical mucosa.

METHODS

A cervical tissue-based organ culture was used to measure antiviral activity of RC-101. Cytotoxicity in tissues was determined by immunostaining of cellular proteins and by measuring inflammatory cytokines using real-time reverse transcriptase-polymerase chain reaction and Luminex technology.

RESULTS

RC-101 blocked transmission of both R5 and X4 HIV-1 across cervical mucosa in this organ culture model. Furthermore, film-formulated RC-101 exhibited potent antiviral activity in organ culture. Such antiviral activity of RC-101 was retained in the presence of semen and vaginal fluid. RC-101 showed no cytotoxicity in cervical tissue. Furthermore, RC-101 did not induce proinflammatory cytokine response in tissues. RC-101 also did not have any effect on natural killer cell activity and proliferation of CD4 and CD8 cells and did not show chemotactic activity.

CONCLUSIONS

Therefore, because of strong antiviral activity and low cytotoxicity in cervical tissues, RC-101 should be considered as an excellent microbicide candidate against HIV-1.

Soluble mediators of inflammation in HIV and their implications for therapeutics and vaccine development

From early in the HIV epidemic it was appreciated that many inflammatory markers such as neopterin and TNF-α were elevated in patients with AIDS. With the advent of modern technology able to measure a broad array of cytokines, we now know that from the earliest points of infection HIV induces a cytokine storm. This review will focus on how cytokines are disturbed in HIV infection and will explore potential therapeutic uses of cytokines. These factors can be used directly as therapy during HIV infection, either to suppress viral replication or prevent deleterious immune effects of infection, such as CD4+ T cell depletion. Cytokines also show great promise as adjuvants in the development of HIV vaccines, which would be critical for the eventual control of the epidemic.

Leishmania induces survival, proliferation and elevated cellular dNTP levels in human monocytes promoting acceleration of HIV co-infection

Leishmaniasis is a parasitic disease that is widely prevalent in many tropical and sub-tropical regions of the world. Infection with Leishmania has been recognized to induce a striking acceleration of Human Immunodeficiency Virus Type 1 (HIV-1) infection in coinfected individuals through as yet incompletely understood mechanisms. Cells of the monocyte/macrophage lineage are the predominant cell types coinfected by both pathogens. Monocytes and macrophages contain extremely low levels of deoxynucleoside triphosphates (dNTPs) due to their lack of cell cycling and S phase, where dNTP biosynthesis is specifically activated. Lentiviruses, such as HIV-1, are unique among retroviruses in their ability to replicate in these non-dividing cells due, at least in part, to their highly efficient reverse transcriptase (RT). Nonetheless, viral replication progresses more efficiently in the setting of higher intracellular dNTP concentrations related to enhanced enzyme kinetics of the viral RT. In the present study, in vitro infection of CD14+ peripheral blood-derived human monocytes with Leishmania major was found to induce differentiation, marked elevation of cellular p53R2 ribonucleotide reductase subunit and R2 subunit expression. The R2 subunit is restricted to the S phase of the cell cycle. Our dNTP assay demonstrated significant elevation of intracellular monocyte-derived macrophages (MDMs) dNTP concentrations in Leishmania-infected cell populations as compared to control cells. Infection of Leishmania-maturated MDMs with a pseudotyped GFP expressing HIV-1 resulted in increased numbers of GFP+ cells in the Leishmania-maturated MDMs as compared to control cells. Interestingly, a sub-population of Leishmania-maturated MDMs was found to have re-entered the cell cycle, as demonstrated by BrdU labeling. In conclusion, Leishmania infection of primary human monocytes promotes the induction of an S phase environment and elevated dNTP levels with notable elevation of HIV-1 expression in the setting of coinfection.

Leishmaniasis is a parasitic disease that infects several human host immune cells, including neutrophils, monocytes, and macrophages. Moreover, while HIV-1 infects monocytes and macrophages, only the infected macrophages productively release viral progenies. Importantly, patients coinfected with both pathogens progress more rapidly to AIDS. In this study, we examine how Leishmania major changes the cellular environment of monocytes in vitro. We found that Leishmania-infected monocytes actively mature into macrophages in the absence of GM-CSF, and that these cells up-regulate the expression of ribonucleotide reductase, an enzyme that catalyzes the formation of deoxynucleoside triphosphates (dNTPs). We confirmed the elevation of dNTP concentrations using a very sensitive dNTP assay for monocytes and monocyte-maturated macrophages. Collectively, these data support a model in which infection of monocytes with Leishmania elevates the intracellular dNTP pools, which is one of the natural anti-viral blocks to HIV-1 infection in monocytes and macrophages in patients.

Variations in the heme oxygenase-1 microsatellite polymorphism are associated with plasma CD14 and viral load in HIV-infected African-Americans

Heme oxygenase-1 (HO-1) is an anti-inflammatory enzyme that maintains homeostasis during cellular stress. Given previous findings that shorter length variants of a HO-1 promoter region GT(n) microsatellite polymorphism are associated with increased HO-1 expression in cell lines, we hypothesized that shorter variants would also be associated with increased levels of HO-1 expression, less inflammation and lower levels of inflammation-associated viral replication in human immunodeficiency virus (HIV)-infected subjects. Healthy donors (n = 20) with shorter GT(n) repeats had higher HO-1 mRNA transcript in peripheral blood mononuclear cells stimulated with lipopolysaccharide (r = -0.38, P = 0.05). The presence of fewer GT(n) repeats in subjects with untreated HIV disease was associated with higher HO-1 mRNA levels in peripheral blood (r = -0.41, P = 0.02); similar observations were made in CD14(+) monocytes from antiretroviral-treated subjects (r = -0.36, P = 0.04). In African-Americans, but not Caucasians, greater GT(n) repeats were correlated with higher soluble CD14 levels during highly active antiretroviral therapy (r = 0.38, P = 0.007) as well as higher mean viral load off-therapy (r = 0.24, P = 0.04). These data demonstrate that the HO-1 GT(n) microsatellite polymorphism is associated with higher levels of HO-1 expression and that this pathway may have important effects on the association between inflammation and HIV replication.

Effects of HIV-1 Nef on virus co-receptor expression and cytokine release in human bladder, laryngeal, and intestinal epithelial cell lines

HIV infections are mainly acquired by mucosal transmission, through oral, rectal, or genital mucosa. Epithelial cells (EC) are the first cells encountered by HIV during infection through sexual transmission and breastfeeding. EC express several receptors critical for both primary HIV infection and secondary transmission. The regulation of co-receptor expression correlates with changes in susceptibility to infection by HIV-1 strains with different tropism. Moreover, inflammatory responses at mucosal surfaces after HIV-1 transmission may influence disease outcome. In the present study, we analyzed the effect of the accessory HIV-1 Nef protein on mucosal EC, using unstimulated or IFN-γ-stimulated HEp-2, T24, and Caco2 cell lines as models for homeostatic or inflamed mucosal tracts. We found that Nef significantly upregulated the expression of CXCR4 on the Caco-2 cell surface and the expression of galactosylceramide on the T24 cell surface. In addition, Nef significantly upregulated IL-6 production by T24 and Caco-2 cells, and TNF-α release by all three cell lines analyzed. Notably, Nef abrogated the IFN-γ-induced modulation of co-receptor expression and cytokine secretion. Our findings suggest that Nef differently regulates co-receptor expression and cytokine secretion at the epithelial level, depending on the anatomical derivation of the cells and the inflammatory status.

Nuclear receptor signaling inhibits HIV-1 replication in macrophages through multiple trans-repression mechanisms

Sexually transmitted pathogens activate HIV-1 replication and inflammatory gene expression in macrophages through engagement of Toll-like receptors (TLRs). Ligand-activated nuclear receptor (NR) transcription factors, including glucocorticoid receptor (GR), peroxisome proliferator-activated receptor gamma (PPARγ), and liver X receptor (LXR), are potent inhibitors of TLR-induced inflammatory gene expression. We therefore hypothesized that ligand-activated NRs repress both basal and pathogen-enhanced HIV-1 replication in macrophages by directly repressing HIV-1 transcription and by ameliorating the local proinflammatory response to pathogens. We show that the TLR2 ligand PAM3CSK4 activated virus transcription in macrophages and that NR signaling repressed both basal and TLR-induced HIV-1 transcription. NR ligand treatment repressed HIV-1 expression when added concurrently with TLR ligands and in the presence of cycloheximide, demonstrating that they act independently of new cellular gene expression. We found that treatment with NR ligands inhibited the association of AP-1 and NF-κB subunits, as well as the coactivator CBP, with the long terminal repeat (LTR). We show for the first time that the nuclear corepressor NCoR is bound to HIV-1 LTR in unstimulated macrophages and is released from the LTR after TLR engagement. Treatment with PPARγ and LXR ligands, but not GR ligands, prevented this TLR-induced clearance of NCoR from the LTR. Our data demonstrate that both classical and nonclassical trans-repression mechanisms account for NR-mediated HIV-1 repression. Finally, NR ligand treatment inhibited the potent proinflammatory response induced by PAM3CSK4 that would otherwise activate HIV-1 expression in infected cells. Our findings provide a rationale for studying ligand-activated NRs as modulators of basal and inflammation-induced HIV-1 replication.

Exogenous HIV-1 Nef upsets the IFN-γ-induced impairment of human intestinal epithelial integrity

Background

The mucosal tissues play a central role in the transmission of HIV-1 infection as well as in the pathogenesis of AIDS. Despite several clinical studies reported intestinal dysfunction during HIV infection, the mechanisms underlying HIV-induced impairments of mucosal epithelial barrier are still unclear. It has been postulated that HIV-1 alters enterocytic function and HIV-1 proteins have been detected in several cell types of the intestinal mucosa. In the present study, we analyzed the effect of the accessory HIV-1 Nef protein on human epithelial cell line.

Methodology/Principal Findings

We used unstimulated or IFN-γ-stimulated Caco-2 cells, as a model for homeostatic and inflamed gastrointestinal tracts, respectively. We investigated the effect of exogenous recombinant Nef on monolayer integrity analyzing its uptake, transepithelial electrical resistance, permeability to FITC-dextran and the expression of tight junction proteins. Moreover, we measured the induction of proinflammatory mediators. Exogenous Nef was taken up by Caco-2 cells, increased intestinal epithelial permeability and upset the IFN-γ-induced reduction of transepitelial resistance, interfering with tight junction protein expression. Moreover, Nef inhibited IFN-γ-induced apoptosis and up-regulated TNF-α, IL-6 and MIP-3α production by Caco-2 cells while down-regulated IL-10 production. The simultaneous exposure of Caco-2 cells to Nef and IFN-γ did not affect cytokine secretion respect to untreated cells. Finally, we found that Nef counteracted the IFN-γ induced arachidonic acid cascade.

Conclusion/Significance

Our findings suggest that exogenous Nef, perturbing the IFN-γ-induced impairment of intestinal epithelial cells, could prolong cell survival, thus allowing for accumulation of viral particles. Our results may improve the understanding of AIDS pathogenesis, supporting the discovery of new therapeutic interventions.

HSV-2 infection of dendritic cells amplifies a highly susceptible HIV-1 cell target

Herpes simplex virus type 2 (HSV-2) increases the risk of HIV-1 infection and, although several reports describe the interaction between these two viruses, the exact mechanism for this increased susceptibility remains unclear. Dendritic cells (DCs) at the site of entry of HSV-2 and HIV-1 contribute to viral spread in the mucosa. Specialized DCs present in the gut-associated lymphoid tissues produce retinoic acid (RA), an important immunomodulator, able to influence HIV-1 replication and a key mediator of integrin α₄β₇ on lymphocytes. α₄β₇ can be engaged by HIV-1 on the cell-surface and CD4⁺ T cells expressing high levels of this integrin (α₄β₇ (high)) are particularly susceptible to HIV-1 infection. Herein we provide in-vivo data in macaques showing an increased percentage of α₄β₇ (high) CD4⁺ T cells in rectal mucosa, iliac lymph nodes and blood within 6 days of rectal exposure to live (n = 11), but not UV-treated (n = 8), HSV-2. We found that CD11c⁺ DCs are a major target of HSV-2 infection in in-vitro exposed PBMCs. We determined that immature monocyte-derived DCs (moDCs) express aldehyde dehydrogenase ALDH1A1, an enzyme essential for RA production, which increases upon HSV-2 infection. Moreover, HSV-2-infected moDCs significantly increase α₄β₇ expression on CD4⁺ T lymphocytes and HIV-1 infection in DC-T cell mixtures in a RA-dependent manner. Thus, we propose that HSV-2 modulates its microenviroment, influencing DC function, increasing RA production capability and amplifying a α₄β₇ (high)CD4⁺ T cells. These factors may play a role in increasing the susceptibility to HIV-1.

Differential response of primary and immortalized CD4+ T cells to Neisseria gonorrhoeae-induced cytokines determines the effect on HIV-1 replication

To compare the effect of gonococcal co-infection on immortalized versus primary CD4(+) T cells the Jurkat cell line or freshly isolated human CD4(+) T cells were infected with the HIV-1 X4 strain NL4-3. These cells were exposed to whole gonococci, supernatants from gonococcal-infected PBMCs, or N. gonorrhoeae-induced cytokines at varying levels. Supernatants from gonococcal-infected PBMCs stimulated HIV-1 replication in Jurkat cells while effectively inhibiting HIV-1 replication in primary CD4(+) T cells. ELISA-based analyses revealed that the gonococcal-induced supernatants contained high levels of proinflammatory cytokines that promote HIV-1 replication, as well as the HIV-inhibitory IFNα. While all the T cells responded to the HIV-stimulatory cytokines, albeit to differing degrees, the Jurkat cells were refractory to IFNα. Combined, these results indicate that N. gonorrhoeae elicits immune-modulating cytokines that both activate and inhibit HIV-production; the outcome of co-infection depending upon the balance between these opposing signals.

TRIM22 inhibits HIV-1 transcription independently of its E3 ubiquitin ligase activity, Tat, and NF-kappaB-responsive long terminal repeat elements

Previous studies identified clones of the U937 promonocytic cell line that were either permissive or nonpermissive for human immunodeficiency virus type 1 (HIV-1) replication. These clones were investigated further in the search for host restriction factors that could explain their differential capacity to support HIV-1 replication. Among known HIV-1 restriction factors screened, tripartite motif-containing protein 22 (TRIM22) was the only factor constitutively expressed in nonpermissive and absent in permissive U937 cells. Stable TRIM22 knockdown (KD) rescued HIV-1 long-terminal-repeat (LTR)-driven transcription in KD-nonpermissive cells to the levels observed in permissive cells. Conversely, transduction-mediated expression of TRIM22 in permissive cells reduced LTR-driven luciferase expression by ∼7-fold, supporting a negative role of TRIM22 in HIV-1 transcription. This finding was further confirmed in the human T cell line A3.01 expressing TRIM22. Moreover, overexpression of TRIM22 in 293T cells significantly impaired basal and phorbol myristate acetate-ionomycin-induced HIV-1 LTR-driven gene expression, whereas inhibition of tumor necrosis factor alpha-induced viral transcription was a consequence of lower basal expression. In agreement, TRIM22 equally inhibited an LTR construct lacking the tandem NF-κB binding sites. In addition, TRIM22 did not affect Tat-mediated LTR transactivation. Finally, these effects were independent of TRIM22 E3 ubiquitin-ligase activity. In the context of replication-competent virus, significantly higher levels of HIV-1 production were observed in KD-nonpermissive versus control nonpermissive U937 cells after infection. In contrast, lower peak levels of HIV-1 replication characterized U937 and A3.01 cells expressing TRIM22 versus their control transduced counterpart. Thus, nuclear TRIM22 significantly impairs HIV-1 replication, likely by interfering with Tat- and NF-κB-independent LTR-driven transcription.

Role of selenium in HIV infection

HIV infection is a global disease that disproportionately burdens populations with nutritional vulnerabilities. Laboratory experiments have shown that selenium has an inhibitory effect on HIV in vitro through antioxidant effects of glutathione peroxidase and other selenoproteins. Numerous studies have reported low selenium status in HIV-infected individuals, and serum selenium concentration declines with disease progression. Some cohort studies have shown an association between selenium deficiency and progression to AIDS or mortality. In several randomized controlled trials, selenium supplementation has reduced hospitalizations and diarrheal morbidity, and improved CD4(+) cell counts, but the evidence remains mixed. Additional trials are recommended to study the effect of selenium supplementation on opportunistic infections, and other HIV disease-related comorbidities in the context of highly active antiretroviral therapy in both developing and developed countries.

Selective serotonin reuptake inhibitor suppression of HIV infectivity and replication

OBJECTIVE

To test the hypothesis that the selective serotonin reuptake inhibitor (SSRI) citalopram would down-regulate human immunodeficiency virus (HIV) infectivity and that the greatest effects would be seen in people with depression. Depression is a risk factor for morbidity and mortality in HIV/acquired immune deficiency syndrome. Serotonin (5-HT) neurotransmission has been implicated in the pathobiology of depression, and pharmacologic therapies for depression target this system. The 5-HT transporter and 5-HT receptors are widely distributed throughout the central nervous and immune systems. Depression has been associated with suppression of natural killer cells and CD8(+) lymphocytes, key regulators of HIV infection.

METHODS

Ex vivo models for acute and chronic HIV infection were used to study the effects of citalopram on HIV viral infection and replication in 48 depressed and nondepressed women. For both the acute and chronic infection models, HIV reverse transcriptase activity was measured in the citalopram treatment condition and the control condition.

RESULTS

The SSRI significantly down-regulated the reverse transcriptase response in both the acute and chronic infection models. Specifically, citalopram significantly decreased the acute HIV infectivity of macrophages. Citalopram also significantly decreased HIV viral replication in the latently infected T-cell line and in the latently infected macrophage cell line. There was no difference in down-regulation by depression status.

CONCLUSIONS

These studies suggest that an SSRI enhances natural killer/CD8 noncytolytic HIV suppression in HIV/acquired immune deficiency syndrome and decreases HIV viral infectivity of macrophages, ex vivo, suggesting the need for in vivo studies to determine a potential role for agents targeting serotonin in the host defense against HIV.

Peripheral blood CCR4+CCR6+ and CXCR3+CCR6+CD4+ T cells are highly permissive to HIV-1 infection

There is limited knowledge on the identity of primary CD4(+) T cell subsets selectively targeted by HIV-1 in vivo. In this study, we established a link between HIV permissiveness, phenotype/homing potential, and lineage commitment in primary CD4(+) T cells. CCR4(+)CCR6(+), CCR4(+)CCR6(-), CXCR3(+)CCR6(+), and CXCR3(+)CCR6(-) T cells expressed cytokines and transcription factors specific for Th17, Th2, Th1Th17, and Th1 lineages, respectively. CCR4(+)CCR6(+) and CXCR3(+)CCR6(+) T cells expressed the HIV coreceptors CCR5 and CXCR4 and were permissive to R5 and X4 HIV replication. CCR4(+)CCR6(-) T cells expressed CXCR4 but not CCR5 and were permissive to X4 HIV only. CXCR3(+)CCR6(-) T cells expressed CCR5 and CXCR4 but were relatively resistant to R5 and X4 HIV in vitro. Total CCR6(+) T cells compared with CCR6(-) T cells harbored higher levels of integrated HIV DNA in treatment-naive HIV-infected subjects. The frequency of total CCR6(+) T cells and those of CCR4(+)CCR6(+) and CXCR3(+)CCR6(+) T cells were diminished in chronically infected HIV-positive subjects, despite viral-suppressive therapy. A high-throughput analysis of cytokine profiles identified CXCR3(+)CCR6(+) T cells as a major source of TNF-alpha and CCL20 and demonstrated a decreased TNF-alpha/IL-10 ratio in CXCR3(+)CCR6(-) T cells. Finally, CCR4(+)CCR6(+) and CXCR3(+)CCR6(+) T cells exhibited gut- and lymph node-homing potential. Thus, we identified CCR4(+)CCR6(+) and CXCR3(+)CCR6(+) T cells as highly permissive to HIV replication, with potential to infiltrate and recruit more CCR6(+) T cells into anatomic sites of viral replication. It is necessary that new therapeutic strategies against HIV interfere with viral replication/persistence in discrete CCR6(+) T cell subsets.

Influence of a vaccination schedule on viral load rebound and immune responses in successfully treated HIV-infected patients

Vaccination is recommended for HIV-infected patients. Transient increases of viral load (VL) and risk of developing resistance to HAART have been described. In addition, VL rebounds could increase HIV-specific immune responses. Twenty-six successfully treated HIV-infected adults were randomized to receive a vaccination schedule or placebo during 12 months. Afterward, HAART was discontinued. Influences of vaccination over VL, genotypic mutations, different T cell subsets, and HIV-1-specific immune responses were evaluated. Patients did not present any secondary effect. No differences in incidence of detectable VL determinations were detected between groups [relative risk 0.54 (95% CI 0.23-1.26)]. No relevant resistance mutations were detected. The vaccinated group showed a significant drop in CD4(+) T cells (p = 0.046) associated with increases in activated T cells. HIV-1-specific lymphoproliferative responses increased more in the vaccinated group during the vaccination period. Viral rebound dynamics after interrupting HAART were similar in both groups. A vaccination schedule in successfully treated HIV patients was safe, was not associated with an increase in detectable VL, and did not increase the risk of developing resistance mutations. However, it induced an increase in T cell activation and a drop in CD4(+) T cells, although these changes did not influence the VL rebound dynamics after HAART interruption.

Evaluation of local tolerance of the antiretroviral spermicide (WHI-07)-loaded gel-microemulsion in the porcine female reproductive tract

The local tolerance of the antiretroviral spermicide, WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate)-loaded gel-microemulsion was evaluated in a physiologically relevant and sensitive porcine model. Gilts (Duroc) in nonestrus stages of the reproductive cycle received either a single or a daily intravaginal application of 2.0% WHI-07 via a gel-microemulsion for 6 days. Cervicovaginal lavage (CVL) fluid was obtained for up to 72 h after a single exposure and the cellular profile and levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) were quantitated by flow cytometry and chemiluminescence-based multiplex immunoassay, respectively. The reproductive tract (vagina, cervix, uteri and Fallopian tubes) harvested on day 7 was scored histologically for evidence of mucosal irritation using a new scoring criterion for ten histological endpoints that reflect pathological changes in the epithelial/ subepithelial and vascular/perivascular compartments. When compared with irritant reactions caused by the detergent-type spermicide, benzalkonium chloride (BZK), the scatter profile of CVL immune cells and basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in CVL fluid were unaffected by intravaginal exposure to 2% WHI-07. Unlike BZK, endpoint histology of the proximal and distal regions of the reproductive tract from gilts treated with 2.0% WHI-07 via gel-microemulsion for 6 days did not result in mucosal irritation or alteration in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues and underlying/surrounding muscles. Based on surrogate markers for inflammation, leukocyte profile and histologic data for local tolerance, repeated intravaginal administration of WHI-07 via gel-microemulsion as a prophylactic contraceptive is unlikely to cause vaginal irritation.

Preclinical evaluation of a dual-acting microbicidal prodrug WHI-07 in combination with vanadocene dithiocarbamate in the female reproductive tract of rabbit, pig, and cat

The mucosal safety of the combination antiretroviral spermicide,WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxy alaninyl phosphate] and vanadocene dithiocarbamate (VDDTC), was evaluated in 3 different animal models. Twenty-seven NZW rabbits in four subgroups were exposed intravaginally to a gel-microemulsion (GM) with and without three dose levels of WHI-07 plus VDDTC (0.5+0.06%, 1.0+0.12% and 2.0+0.25%) or 4% nonoxynol-9 (N-9; Conceptrol) for 14 consecutive days. Ten nonestrus gilts (Duroc) in three subgroups received either a single or daily intravaginal application of GM with and without 2.0% WHI-07 plus 0.25% VDDTC or 2.0% benzalkonium chloride (BZK)-containing gel for 6 and 4 consecutive days, respectively. Five cats received a single intravaginal application of GM incorporating 2.0% WHI-07 plus 0.25% VDDTC. Genital tract histopathology was performed in the pig and rabbit at the end of dosing period but after 18 weeks post-dosing in the cat. Porcine cervicovaginal lavage (CVL) fluid was obtained for up to 72 hours after a single exposure and changes in the levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma, and TNF-alpha) were quantitated by a multiplexed chemiluminescence-based immunoassay. Rabbit vaginal tissues were evaluated for localized cellular inflammation and in situ apoptosis by immunohistochemical staining for CD45, nuclear factor (NF)-kappa B, and terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick-end labeling (TUNEL) using confocal laser scanning microscopy (CLSM), respectively. Vanadium content in selected organs and body fluids from rabbits and pigs was determined by atomic absorption spectroscopy. When compared with 4% N-9 (total irritation score 13-14 out of a possible 16), none of the rabbits given WHI-07 plus VDDTC intravaginally, developed histological alterations such as epithelial erosion, edema, leukocyte influx or vascular congestion characteristic of inflammation (total irritation score 4-6). CD45 and NF-kappa B immunoreactivity was limited to cells within the vascular lumen of both control and WHI-07 plus VDDTC-treated vaginal tissues. TUNEL assay revealed lack of increased apoptotic cells in vaginal mucosa exposed to increasing concentrations of WHI-07 plus VDDTC. Basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in porcine CVL were unaffected by intravaginal exposure to WHI-07 plus VDDTC when compared with BZK used as a positive control. Endpoint histology of the reproductive tract from cats and pigs after a single or repeated intravaginal exposure to WHI-07 plus VDDTC, respectively, revealed lack of irritation/inflammation in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues, and underlying/surrounding muscles. Vanadium was not preferentially incorporated into rabbit or porcine tissues and body fluids at levels above 1 microg/g. Based on comparative histologic data and surrogate markers for inflammation, repeated intravaginal administration of WHI-07 plus VDDTC via a gel-microemulsion did not result in vaginal irritation, mucosal toxicity, or systemic absorption of vanadium. Therefore, the combined use of WHI-07 and VDDTC via gel-microemulsion appears safe for topical use as a prophylactic anti-HIV microbicide.

HIV-1 p17 binds heparan sulfate proteoglycans to activated CD4(+) T cells

We have previously shown that HIV-1 p17 binds to activated peripheral blood mononuclear cells and enhances secretion of pro-inflammatory cytokines, but we were unable to define a ligand on activated cells. In this work we evaluate the hypothesis that HIV-1 p17 may be a heparin/heparan sulfate-binding protein. HIV-1 p17 contains C- and N-terminal sequences with positively charged residues and a consensus cluster for heparin binding. We demonstrated by affinity chromatography that HIV-1 p17 binds strongly to heparin-agarose at physiological pH. Soluble heparins and heparan sulfate but not chondroitin 4-sulfate and dextran sulfate inhibit binding of HIV-1 p17 to heparin solid phase and to activated CD4(+) T cells. Furthermore the inhibition of cell sulfatation by chlorate treatment completely counteracts HIV-1 p17 binding to activated cells. These results indicate for the first time that HIV-1 p17 can be ascribed to the heparin binding protein family and suggest that this interaction might play a key role in the ability of the protein to induce an inflammatory effect on activated cells.

HIV-1 Nef impairs the dynamic of DC/NK crosstalk: different outcome of CD56(dim) and CD56(bright) NK cell subsets

Dendritic cells (DCs) and natural killer (NK) cells are essential components of the innate immunity and play a critical role in the first phase of host defense against infection. Interactions between DCs and NK cells have been demonstrated in a variety of settings, with evidence emerging of complex bidirectional crosstalk between the two cell types. The accessory HIV-1 Nef protein is a crucial determinant for viral replication and pathogenesis. We previously demonstrated that Nef, hijacking DC functional activity, subverts the DC arm of immune response to escape the adaptive immune attack. Here, we monitor the effect of Nef on the outcome of the innate immune response, focusing on the impact of Nef on DC/NK crosstalk. We demonstrate that Nef up-regulates the ability of DCs to stimulate the immunoregulatory NK cells (CD56(bright)) as assessed by the activated phenotype, up-regulation of their proliferative response and INF-gamma release. On the other hand, Nef-pulsed DCs inhibit cytotoxic NK cells (CD56(dim)), as assessed by the reduced HLA-DR surface expression, reduced proliferation and cytotoxic activity. Moreover, in the presence of Nef-pulsed DCs, we found a significant up-regulation of TNF-alpha secretion and a significant reduction of IL-10, GM-CSF, MIP-1alpha and RANTES secretion. Our findings suggest that the Nef-induced dysregulation in the DC/NK cell crosstalk may represent a potential mechanism through which HIV escapes innate immune surveillance.

Comprehensive Proteomic Analysis of Human Cervical−Vaginal Fluid

Cervical-vaginal fluid (CVF) is a potential rich source of biomarkers for enhancing our understanding of human parturition and pathologic conditions affecting pregnancy. In this study, we performed a comprehensive survey of the CVF proteome in pregnancy utilizing multidimensional liquid chromatography (2D-LC) coupled with mass spectrometry and gel-electrophoresis-based protein separation and identification. In total, 150 unique proteins were identified using multiple protein identification algorithms. Metabolism (32%) and immune response-related (22%) proteins are the major functional categories represented in the CVF proteome. A comparison of the CVF, serum, and amniotic fluid proteomes showed that 77 proteins are unique to CVF, while 56 and 17 CVF proteins also occur in serum and amniotic fluid, respectively. This data set provides a foundation for evaluation of these proteins as potential CVF biomarkers for noninvasive diagnosis of pregnancy-related disorders.

Early immune activation in gut-associated and peripheral lymphoid tissue during acute HIV infection

OBJECTIVE

To study innate and adaptive immune responses in gut-associated lymphoid tissue (GALT) as well as peripheral lymphoid tissue (pLT) obtained from individuals with acute HIV-1 infection syndrome.

DESIGN

The expression of chemokines [regulated upon activation: normal T cell expressed/secreted (RANTES), macrophage-inflammatory protein (MIP) 1alpha/beta], cytokines (IL-1beta, TNF-alpha, IL-12, IL-4, IL-10, IL-2, IFN-gamma) and cytotoxic effector molecules (granzyme A, perforin) and cell marker (CD8) were analysed at the single cell level in GALT and pLT of patients experiencing acute HIV-1 infection (day -3 to 48 days from onset of acute symptoms).

RESULTS

Substantial pro-inflammatory immune responses (TNF-alpha, IL-1beta, IL-12) and expansion in the CD8 T-cell population were noted in both compartments compared with uninfected controls. This was associated with an early increased expression of beta-chemokines (RANTES, MIP-1alpha/beta) and granzyme, but not with an increase in the expression of perforin. The upregulation of IL-2, IL-12 and IL-4 was noted in both pLT and GALT, whereas IL-10 expression was mainly increased in GALT.

CONCLUSION

Taken together, these findings demonstrate that there was a broad and early immune activation in GALT and pLT during acute HIV-1 infection. The relative lack of perforin expression in both GALT and pLT, however, questions the functional efficacy of the observed immune activation in generating cytotoxic T cells that were able to eliminate HIV-infected cells.

HIV-1 Matrix Protein p17 Modulatesin VivoPreactivated Murine T-Cell Response and Enhances the Induction of Systemic and Mucosal Immunity Against Intranasally Co-administered Antigens

HIV-1 p17 is a viral cytokine that acts on preactivated, but not on resting, human T cells promoting proliferation, proinflammatory cytokines release and HIV-1 replication, after binding to a cellular receptor (p17R). Here, we demonstrate that p17Rs are expressed on activated murine T cells, which respond to p17 stimulation similarly to their human counterpart. We developed a mouse model of abortive HSV-1 infection to induce T cell activation in vivo. Preactivated cells expressed p17Rs and were highly susceptible to p17 stimulation, which triggered proinflammatory cytokines release and promoted CD4+ T cell survival and expansion. Coculture of in vivo activated splenocytes with macrophages in the presence of p17 further increased their ability to produce IFN-gamma. The presence of macrophages and activated T cells at mucosal sites prompted us to investigate the immunomodulatory activities of p17 in vivo. Intranasal coadministration of p17 with beta-galactosidase (beta-gal) resulted in improved beta-gal specific cellular and humoral immune responses at systemic and mucosal levels. It is well established that HIV-1 replication is driven in an autocrine/paracrine manner by endogenously produced proinflammatory cytokines. Our results highlight the role of p17 in sustaining cellular activation and inflammation, thereby promoting a permissive microenvironment for HIV-1 replication. In addition, p17 is a promising candidate antigen, exhibiting immunomodulatory/adjuvant properties, that need to be exploited in the development of HIV/AIDS vaccines.

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.

Dawn of non-nucleoside inhibitor-based anti-HIV microbicides

The emergence of HIV/AIDS as a disease spread through sexual intercourse has prompted the search for safe and effective vaginal and rectal microbicides for curbing mucosal viral transmission via semen. Since endogenous reverse transcription is implicated in augmenting the sexual transmission of HIV-1 infection, potential microbicides should have the inherent ability to optimally inhibit both wild-type and drug-escape mutants. The non-nucleoside reverse transcriptase inhibitors (NNRTIs), which bind to an allosteric site on RT, are an important arsenal of drugs against HIV-1. The clinical success of NNRTI-based HIV/AIDS therapies has led to extensive structural and molecular modelling studies of enzyme complexes and chemical synthesis of second- and third-generation NNRTIs. Rationally designed NNRTIs deduced from changes in binding pocket size, shape and residue character that result from clinically observed NNRTI resistance-associated mutations exhibit high binding affinity for HIV-1 RT and robust anti-HIV activity against the wild-type and drug-escape mutants without cytotoxicity. Notably, membrane permeable tight binding NNRTIs have the ability to inactivate cell-free as well as cell-associated HIV-1 in semen without metabolic activation. Consequently, NNRTIs currently under development as experimental microbicides include thiourea-PETT (where PETT stands for phenethylthiazolylthiourea) derivatives (PHI-236, PHI-346 and PHI-443), urea-PETT derivatives (MIV-150), oxypyrimidines (S-DABOs), thiocarboxanilides (UC-781) and diarylpyrimidines (TMC-120). Mucoadhesive formulations of these NNRTIs have been studied for safety and efficacy in animal models and some have entered Phase I safety testing in humans. This review focuses on the structural, biological and preclinical studies relevant to the clinical development of these NNRTIs as molecular virucides intended to prevent the sexual transmission of HIV-1.

HIV p17 reverses the anti-inflammatory activity of IL-4 on IL-15 stimulated monocytes and modulates their ability to secrete MIP-1 alpha

Monocytes play a central role in the immune system by producing and reacting to different soluble factors. Cytokine dysregulation is an hallmark in HIV-infected individuals and it is one of the most significant factors leading to impaired immunity in HIV/AIDS disease. This study investigates the possibility of modulation in the secretion of some inflammatory cytokines and chemokines induced by HIV p17 in monocytes. The results show that p17, while ineffective on resting monocytes, exerts an inflammatory action on IL-4 mediated inhibition of TNF-alpha and IFN-gamma production induced by IL-15 stimulation. In addition, p17 is able to reduce MIP-1alpha secretion, but unable to influence IL-6 production. The ability of HIV p17 to contribute to an altered pattern of secreted soluble factors might imply a key role for this viral protein in the development of AIDS pathogenesis.

Modulatory effect of mannose-binding lectin on cytokine responses: possible roles in HIV infection

BACKGROUND

Mannose-binding lectin (MBL) is a soluble receptor of the innate immune system, probably contributing to antimicrobial defence. The possible role of MBL in HIV infection is unclear.

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMCs) from 28 HIV-infected patients and 13 healthy controls were stimulated with MBL and costimulated with HIV-1 gp120 or mannan from Saccharomyces cerevisiae before inflammatory responses in PBMC cultures were examined by enzyme-linked immunosorbent assay (ELISA) and flow cytometry. HIV-1 RNA replication in vitro was assessed by quantitative reverse transcription polymerase chain reaction (RT-PCR) in supernatants from patients with measurable HIV-1 RNA levels.

RESULTS

(i) Enhanced TNF-alpha responses were observed when PBMCs from healthy controls and HIV-infected patients were stimulated with MBL and costimulated with HIV-1 gp120 or mannan. (ii) MBL stimulation induced increased HIV RNA replication in culture supernatants when costimulated with mannan.

CONCLUSIONS

The present study suggests a modulatory role of MBL on cytokine responses, and HIV replication after stimulation with microbial products. These effects of MBL on inflammatory responses and viral replication may be clinically relevant for HIV infection.

Serum Neopterin, an Immune Activation Marker, Independently Predicts Disease Progression in Advanced HIV-1 Infection

BACKGROUND

CD4+ T lymphocyte (CD4) counts and plasma human immunodeficiency virus (HIV) type 1 RNA concentrations predict clinical outcome in HIV-1 infection. Our objective was to assess the independent prognostic value for disease progression of soluble markers of immune system activation.

METHODS

This retrospective marker-validation study utilized previously obtained clinical and laboratory data, including CD4+ cell counts, and made use of stored frozen serum samples to assay for levels of beta2-microglobulin, neopterin, endogenous interferon, triglycerides, interleukin-6, soluble tumor necrosis factor- alpha receptor II, and HIV-1 RNA, and to determine HIV genotypic reverse-transcriptase inhibitor resistance. The 152 patients who participated in this study represented a subsample of participants in AIDS Clinical Trials Group (ACTG) 116B/117, a randomized trial that demonstrated the clinical benefit of didanosine over zidovudine monotherapy in persons with advanced HIV-1 infection. Marker data were analyzed in relation to protocol-defined clinical disease progression, using Cox proportional hazards models.

RESULTS

The median duration of follow-up was 344 days. Elevated baseline values for neopterin (P=.0009), endogenous interferon (P=.00039) and interleukin-6 (P=.0007) were each associated with greater subsequent risk of clinical disease progression. In a head-to-head comparison that was adjusted for CD4+ cell count (P=.0165) and HIV-1 RNA level (P=.1220), we found that elevated values for neopterin (P=.0002) and, to a lesser extent, endogenous interferon (P=.0053) were the strongest predictors of increased risk of clinical disease progression 6 months later.

CONCLUSIONS

Soluble markers of immune activation add prognostic information to CD4 counts and viral load for risk of disease progression in advanced HIV-1 infection. The robust performance of neopterin, an inexpensive and reliably measured serum marker, supports its potential suitability for patient monitoring, particularly in resource-limited settings.

Chronic immune activation associated with chronic helminthic and human immunodeficiency virus infections: role of hyporesponsiveness and anergy

Chronic immune activation is one of the hallmarks of human immunodeficiency virus (HIV) infection. It is present also, with very similar characteristics, in very large human populations infested with helminthic infections. We have tried to review the studies addressing the changes in the immune profiles and responses of hosts infected with either one of these two chronic infections. Not surprisingly, several of the immune derangements and impairments seen in HIV infection, and considered by many to be the "specific" effects of HIV, can be found in helminth-infected but HIV-noninfected individuals and can thus be accounted for by the chronic immune activation itself. A less appreciated element in chronic immune activation is the immune suppression and anergy which it may generate. Both HIV and helminth infections represent this aspect in a very wide and illustrative way. Different degrees of anergy and immune hyporesponsiveness are present in these infections and probably have far-reaching effects on the ability of the host to cope with these and other infections. Furthermore, they may have important practical implications, especially with regard to protective vaccinations against AIDS, for populations chronically infected with helminths and therefore widely anergic. The current knowledge of the mechanisms responsible for the generation of anergy by chronic immune activation is thoroughly reviewed.

Adverse hepatic drug reactions: inflammatory episodes as consequence and contributor

Susceptibility to drug toxicity is influenced by a variety of factors, both genetic and environmental. The focus of this article is the evidence addressing the hypothesis that inflammation is both a result of and a susceptibility factor for drug toxicity, with an emphasis on liver as a target organ. Results of studies suggesting a role for inflammatory mediators in the hepatotoxicity caused by acetaminophen or ethanol are discussed. For several drugs, the evidence from animal models that concurrent inflammation increases injury is presented. In addition, the occurrence of adverse drug reactions in people with preexisting inflammatory diseases is considered. The special case of idiosyncratic drug reactions is discussed and the potential raised for development of animal models for this type of drug toxicity. The conclusion is that inflammatory factors should be considered as determinants of sensitivity to adverse drug reactions.

Effect of pregnancy and human immunodeficiency virus infection on intracellular interleukin-2 production patterns

Human immunodeficiency virus type 1 (HIV-1) infection decreases the production of interleukin-2 (IL-2) from CD4+ and CD8+ T cells. Recombinant IL-2 (rIl-2) has been given to HIV-infected individuals to generate significant increases in CD4+ T-cell counts. There are limited data regarding the effects of pregnancy and HIV infection on IL-2 production in humans. To investigate the effects of human pregnancy, HIV infection, and HIV therapy on IL-2 production, we evaluated 61 women. Intracellular IL-2 production by CD4+ T cells from nonpregnant HIV-infected women was significantly lower than in that in uninfected women (45% +/- 8% versus 52% +/- 8%, P = 0.04). In contrast, there was no difference in levels of intracellular IL-2 production between HIV-infected and uninfected pregnant women. These observations suggest that pregnancy may down-regulate IL-2 production regardless of HIV infection status. Future studies should evaluate IL-2 production patterns in larger cohorts of women so that the physiological significance of IL-2 down-regulation in pregnancy can be further evaluated. This information is essential to assess the possible use of IL-2 supplementation therapy as a means of enhancing immune responses among HIV-infected pregnant women.

Markers of local immunity in cervico-vaginal secretions of HIV infected women: implications for HIV shedding

OBJECTIVES

To link local proinflammatory cytokines with HIV related nucleic acids in cervico-vaginal secretions and the factors associated with them.

METHODS

An observational study on 60 HIV positive women attending the department of obstetrics and gynaecology, University of Pavia, Italy. HIV-1 RNA in plasma, proviral HIV-1-DNA, cell associated and cell free HIV-1 RNA in cervico-vaginal secretions were evaluated by competitive polymerase chain reaction (c-PCR) and reverse transcriptase PCR (cRT-PCR). IL-1beta, IL-6, and TNF-alpha were measured by ELISA in cervico-vaginal lavages. Multiple regression analysis on ordinal categorical variables was used to test for the simultaneous associations of clinical and microbiological variables on quartiles of cytokine concentrations in lavage samples.

RESULTS

Proviral HIV-1 DNA, cell associated and cell free HIV-1 RNA were detected in 76.7% (46/60), 70% (42/60), and 71.7% (43/60) of the patients, respectively. IL-1beta concentration was directly correlated with proviral HIV-DNA (Spearman rho = 0.35, p = 0.01) and cell associated HIV-RNA levels (Spearman rho = 0.263, p = 0.05). IL-1beta concentration (153.9 pg/ml) was higher (p<0.05) among women with cytological squamous intraepithelial lesion (SIL) than negative controls (73.4 pg/ml). In women with vaginal infection both IL-1beta (41.7 pg/ml) and IL-6 (10.2 pg/ml) were lower (p<0.05) in comparison to negative controls (144.9 pg/ml and 23.7 pg/ml, respectively). Women receiving stable antiretroviral therapy had significantly lower TNF-alpha (34.4 pg/ml versus 44.4 pg/ml, p = 0.04) and higher IL-6 (24.0 pg/ml versus 1.4 pg/ml, p = 0.004) levels in lavage samples compared to untreated women. The associations between the presence of SIL, antiretroviral treatment, vaginal infection and cytokine concentrations in cervico-vaginal secretions were confirmed in multiple regression analysis.

CONCLUSIONS

Local immune activation may modulate HIV-1 shedding in cervico-vaginal secretion with possible influence on vaginal physiology and host defence. Pharmacological agents lowering HIV-1 replication cause a shift to a pattern of cytokine production which seems less favourable to the transmission of the disease.

Cytokine networks are pre-activated in T cells from HIV-infected patients on HAART and are under the control of cAMP

OBJECTIVE

Cytokines seem to play a critical role in HIV infection. The cAMP/protein kinase A (PKA) type I pathway is shown to be hyper-activated and contributes to T-cell immune dysfunction in HIV infection. Here, we analysed firstly the levels of cytokine gene expression in unstimulated CD3+T cells from HIV-infected patients on HAART, and secondly the regulation of cytokine and cytokine-related genes by cAMP agonist and antagonist in anti-CD3 activated T cells in order to understand their effects on cytokine networks.

METHODS

Cytokine Macro Array and real-time RT-PCR techniques were used to study cytokine gene expression in T cells of HIV-positive patients.

RESULTS

Of the cytokine-related genes analysed 45% were expressed at twofold or higher levels in unstimulated T cells from HIV-infected patients as compared with healthy controls, and one-third of these genes were hypo-responsive upon activation as compared with controls. Furthermore, cAMP modulated levels of expression of a number of cytokine-related genes differently in patient and control T cells. CXCR4, CCR5 and amphiregulin were up-regulated by cAMP agonist, whereas other cytokine-related genes including macrophage inflammatory protein 1 beta, tumour necrosis factor-alpha and lymphotoxin-beta were markedly down-regulated by cAMP agonist in T cells from both HIV-infected patients and controls. Moreover, members of the chemokine/chemokine receptor family were over-represented among genes regulated by cAMP agonist/antagonist in patient T cells.

CONCLUSIONS

Our data indicate that T cells from HIV-infected patients are in a pre-activated state and that a set of cytokine genes is hypo-responsive to activation and under tonic regulation by cAMP in these T cells.

The induction of Toll-like receptor tolerance enhances rather than suppresses HIV-1 gene expression in transgenic mice

Microbial-induced proinflammatory pathways are thought to play a key role in the activation of human immunodeficiency virus type 1 (HIV-1) gene expression. The induction of Toll-like receptor (TLR) tolerance leads to a complex reprogramming in the pattern of inflammatory gene expression and down-modulates tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1, and IL-6 production. Using transgenic (Tg) mice that incorporate the entire HIV-1 genome, including the long-terminal repeat, we have previously demonstrated that a number of different TLR ligands induce HIV-1 gene expression in cultured splenocytes as well as purified antigen-presenting cell populations. Here, we have used this model to determine the effect of TLR-mediated tolerance as an approach to inhibiting microbial-induced viral gene expression in vivo. Unexpectedly, Tg splenocytes and macrophages, rendered tolerant in vitro to TLR2, TLR4, and TLR9 ligands as assessed by proinflammatory cytokine secretion and nuclear factor-kappaB activation, showed enhanced HIV-1 p24 production. A similar enhancement was observed in splenocytes tolerized and then challenged with heterologous TLR ligands. Moreover, TLR2- and TLR4-homotolerized mice demonstrated significantly increased plasma p24 production in vivo despite lower levels of TNF-alpha. Together, these results demonstrate that HIV-1 expression is enhanced in TLR-reprogrammed host cells, possibly reflecting a mechanism used by the virus to escape the effects of microbial-induced tolerance during natural infection in vivo.

Thalidomide Inhibits Tumor Necrosis Factor-α Production and Antigen Presentation by Langerhans Cells

Thalidomide is an effective treatment for several inflammatory and autoimmune disorders including erythema nodosum leprosum, Behcet's syndrome, discoid lupus erythematosus, and Crohn's disease. Thalidomide is believed to exert its anti-inflammatory effects, at least in part, by inhibiting tumor necrosis factor-alpha (TNF-alpha) production by monocytes. We studied the effects of thalidomide on epidermal Langerhans cells (LC). LCs are epidermal antigen-presenting dendritic cells that play important roles in skin immune responses. Using the murine epidermis-derived dendritic cell lines, XS106A from A/J mice and XS52 from BALB/c mice as surrogates for LC, we found that thalidomide inhibited TNF-alpha production in a concentration-dependent manner. Northern blot analysis revealed that thalidomide significantly decreased the peak-induced mRNA level of TNF-alpha in XS106A cells and XS52 cells. We then examined the effect of thalidomide on fresh LC enriched to approximately 98% using positive selection of Ia+ cells with antibodies conjugated to magnetic microspheres. TNF-alpha production was reduced by 67.7% at a thalidomide concentration of 200 microg per mL. Thalidomide also had a profound inhibitory effect on the ability of LC to present antigen to a responsive TH1 clone. Thalidomide inhibits TNF-alpha production and the antigen-presenting ability of epidermal LCs. These mechanisms may contribute to the therapeutic effects observed with this agent.

Detection of infectious human immunodeficiency virus type 1 in female genital secretions by a short-term culture method

Infectious human immunodeficiency virus type 1 (HIV-1) is difficult to detect in female genital secretions by standard virus culture techniques. To improve detection of cell-free HIV-1 in female genital secretions, we adapted a short-term assay that uses the multinuclear-activation galactosidase indicator (MAGI) assay. When vaginal lavages from HIV-1-infected women were tested with the adapted MAGI assay, 25 (64%) of 39 lavages with detectable, cell-free HIV-1 RNA were shown to have infectious virus. No infectious virus was found in 10 vaginal lavages from HIV-1-infected women with undetectable vaginal viral loads. Significantly (P < 0.01) more lavages from HIV-1-infected women tested positive for infectious virus by the MAGI assay than by standard peripheral blood mononuclear cell (PBMC) coculture, which detected infectious virus in only 6 (17%) of 35 vaginal lavages. Lavages with viral loads of >10,000 copies per lavage yielded significantly (P < 0.01) more positive cultures than those with <10,000 copies by using the MAGI assay. Detection of infectious HIV-1 in vaginal lavages was not associated with the presence of genital tract infections or CD4(+)-T-cell counts. However, although the results were not significant (P = 0.08), the MAGI assay detected infectious virus from more vaginal lavages at a vaginal pH of >/=4.5 than at a pH of <4.5. These results indicate that the MAGI assay is more sensitive than PBMC culture methods for detecting infectious virus in female genital secretions. Accurate measurements of infectious virus in genital secretions will improve studies that evaluate sexual transmission of HIV-1.

Virion-bound ICAM-1 and activated LFA-1: a combination of factors conferring resistance to neutralization by sera from human immunodeficiency virus type 1-infected individuals independently of the disease status and phase

The role of the supplementary interaction between virion-bound host ICAM-1 and LFA-1 on target cells in sensitivity to neutralization of human immunodeficiency virus type 1 (HIV-1) is poorly studied. Serum samples from four long-term nonprogressors (LTNPs) and sequential sera from one progressor were used to assess neutralization sensitivity of isogenic ICAM-1-negative and ICAM-1-bearing HIV-1(NL4-3), a prototype of T-cell-line-adapted viruses. We found that virus neutralization sensitivity to the studied sera is not modified by the additional interaction between virally embedded ICAM-1 and LFA-1 under an inactive state. However, expression on the target cell surface of an activated LFA-1 form renders ICAM-1-bearing virus particles, but not viruses devoid of ICAM-1, more refractory to neutralization by sera from three out of four LTNPs and all sequential sera from the person who has experienced a progression of the HIV-1-associated disease. Although no conclusive correlation could be drawn between virus susceptibility to neutralization and the disease status or stages of HIV-1 infection, these findings demonstrate that other nonspecific virus-cell interactions mediated by virion-anchored host proteins and their normal cognate ligands on target cells represent factors that can affect the mechanism of HIV-1 neutralization.

Induction of apoptosis by HIV-1-infected monocytic cells

We have previously described a soluble 6000-Da peptide produced by an HIV-1-infected human macrophage cell line, clone 43(HIV), which induces apoptosis in T and B cells. We have identified this factor as the novel cDNA clone FL14676485 that encodes for the human hypothetical protein, FLJ21908. The FL14676485 cDNA clone was isolated from a 43(HIV) lambda ZAP Escherichia coli expression library and screened with a panel of rabbit and mouse anti-apoptotic Abs. We transfected the FL14676485 clone into Bosc cells and non-HIV-1-infected 43 cells. Western blot analysis of lysates from the FL14676485-transfected 43 cells and Bosc cells using anti-proapoptotic factor Abs revealed a protein with a molecular mass of 66 kDa corresponding to the size of the full-length gene product of the FL14676485 clone, while Western blot of the supernatant demonstrated a doublet of 46-kDa and 6000-Da peptide that corresponds to our previously described proapoptotic factor. Primary HIV-1(BaL)-infected monocytes also produce the FLJ21908 protein. Supernatants from these transfected cells induced apoptosis in PBMC, CD4(+), and CD8(+) T and B cells similar to the activity of our previously described proapoptotic factor. PCR analysis of 43 cells and 43(HIV) cells revealed a base pair fragment of 420 bp corresponding to the FL14676485 gene product in 43(HIV) cells, but not in 43 cells. The FLJ21908 protein induces apoptosis through activation of caspase-9 and caspase-3. We have further demonstrated that the FLJ21908 protein has apoptotic activity in the SH-SY5Y neuronal cell line and can be detected in brain and lymph tissue from HIV-1-infected patients who have AIDS dementia. The FLJ21908 protein may contribute to the apoptosis and dementia observed in AIDS patients.

HIV-1 matrix protein p17 enhances the proliferative activity of natural killer cells and increases their ability to secrete proinflammatory cytokines

We investigated the effects of human immunodeficiency type-1 virus (HIV-1) matrix protein p17 on freshly isolated and purified human natural killer (NK) cells. HIV-1 p17 increased the cytokines interleukin (IL) 2, IL-12 and IL-15, and induced natural killer cell proliferation, but not cytotoxicity. This effect was specific because it was abrogated by anti-p17 monoclonal antibody. Moreover, HIV-1 p17 enhanced the cytokine-induced production of tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma by NK cells. IL-4 downregulated IFN-gamma and TNF-alpha secretion in IL-2- and IL-15-treated NK cells. HIV-1 p17 restored the ability of NK cells to produce both cytokines when added to the cultures simultaneously with IL-4. The property of p17 to increase the production of TNF-alpha and IFN-gamma might be a mechanism used by HIV-1 to modulate the immune system to support its replication and spreading.