Impaired neutrophil function in patients with AIDS or AIDS-related complex: a comprehensive evaluation

Cells of the Innate and Adaptive Immune Systems in Kaposi's Sarcoma

Kaposi's sarcoma (KS) is an angioproliferative malignancy whose associated etiologic agent is the Kaposi's sarcoma-associated herpesvirus (KSHV). KS is the most prevalent malignancy among HIV-infected individuals globally and is considered an AIDS-defining malignancy. The different forms of KS including HIV-associated KS, iatrogenic (immunosuppression-related) KS, and classical KS in elderly males suggest that immune cell dysregulation is among the key components in promoting KS development in KSHV-infected individuals. It is therefore expected that different cell types of the immune system likely play distinct roles in promoting or inhibiting KS development. This narrative review is focused on discussing cells of the innate and adaptive immune systems in KSHV infection and KS pathogenesis, including how these cells can be useful in the control of KSHV infection and treatment of KS.

Treating bacterial pneumonia in people living with HIV

Introduction: Bacterial pneumonia remains an important cause of morbidity and mortality in people living with HIV (PLWH) in the antiretroviral therapy (ART) era. In addition to being immunocompromised, as reflected by low CD4 cell counts and elevated HIV viral loads, PLWH often have other behaviors associated with an increased risk of pneumonia including smoking and injected drug use. As PLWH are aging, comorbid conditions such as chronic obstructive pulmonary disease (COPD), cancers, and cardiovascular, renal and liver diseases are emerging as additional risk factors for pneumonia. Pathogens are often similar to those in HIV-uninfected individuals; however, PLWH are at risk for unusual and/or multi-drug resistant organisms causing bacterial pneumonia based, in part, on their CD4 cell counts and other exposures. Areas covered: In this review, we focus on the recognition and management of bacterial community-acquired pneumonia (CAP) in PLWH. Along with antimicrobial treatment, we discuss prevention strategies such as vaccination and smoking cessation. Expert opinion: Early initiation of ART after HIV infection can decrease the risk of pneumonia. Improved efforts at vaccination, smoking cessation, and reduction of other substance use are urgently needed in PLWH to decrease the risk for bacterial pneumonia. As PLWH are aging, comorbidities are additional risk factors for bacterial CAP.

The Dual Role of Neutrophils in HIV Infection

PURPOSE OF REVIEW

We summarize what is known about neutrophils in HIV infection, focusing on their potential roles in HIV protection, acquisition, and pathogenesis.

RECENT FINDINGS

Recent studies have demonstrated that neutrophil-associated proteins and cytokines in genital tissue pre-infection associate with HIV acquisition. However, recent in vivo assessment of highly exposed seronegative individuals and in vitro studies of anti-HIV functions of neutrophils add to older literature evidence that neutrophils may be important in a protective response to HIV infection. Neutrophils are important for containment of pathogens but can also contribute to tissue damage due to their release of reactive oxygen species, proteases, and other potentially harmful effector molecules. Overall, there is a clear evidence for both helpful and harmful roles of neutrophils in HIV acquisition and pathogenesis. Further study, particularly of tissue neutrophils, is needed to elucidate the kinetics, phenotype, and functionality of neutrophils in HIV infection to better understand this dichotomy.

Pulmonary Innate Immune Dysfunction in Human Immunodeficiency Virus

The advent of antiretroviral therapy has transformed infection by the type 1 human immunodeficiency virus (HIV) from a rapidly fatal disease to a chronic illness with excellent long-term survival rates. Although HIV primarily targets the adaptive arm of host immunity, it simultaneously impacts the innate immune system, and has profound implications for lung health, even when viral suppression is achieved with antiretroviral therapy. The lung has evolved a unique array of innate immune defenses, and the pathophysiological interactions between HIV and the pulmonary innate immune system deserve particular attention. In this review, we discuss work that elucidates how the components of innate immunity both respond to and are perturbed by infection with HIV.

The Host Cytokine Responses and Protective Immunity in Oropharyngeal Candidiasis

Over the last three decades, the prevalence of oropharyngeal fungal infections has increased enormously, mainly due to an increasing population of immunocompromised patients, including individuals with HIV infection, transplant recipients, and patients receiving cancer therapy. The vast majority of these infections are caused by Candida species. The presence of cytokines in infected tissues ultimately dictates the host defense processes that are specific to each pathogenic organism. During oral infection with Candida, a large number of pro-inflammatory and immunoregulatory cytokines are generated in the oral mucosa. The main sources of these cytokines are oral epithelial cells, which maintain a central role in the protection against fungal organisms. These cytokines may drive the chemotaxis and effector functions of innate and/or adaptive effector cells, such as infiltrating neutrophils and T-cells in immunocompetent hosts, and CD8+ T-cells in HIV+ hosts. Epithelial cells also have direct anti- Candida activity. Several studies have provided a potential link between lower levels of certain pro-inflammatory cytokines and susceptibility to oral C. albicans infection, suggesting that such cytokines may be involved in immune protection. The exact role of these cytokines in immune protection against oropharyngeal candidiasis is still incompletely understood and requires further investigation. Identification of such cytokines with the ability to enhance anti-fungal activities of immune effector cells may have therapeutic implications in the treatment of this oral infection in the severely immunocompromised host.

Effect of Antiretroviral Therapy on HIV-mediated Impairment of the Neutrophil Antimycobacterial Response

RATIONALE

Experimental and epidemiological evidence suggests that neutrophils are important in the host response to tuberculosis. HIV infection, which increases the risk of tuberculosis, adversely affects neutrophil function.

OBJECTIVES

To determine the impact of HIV and antiretroviral therapy on neutrophil antimycobacterial activity.

METHODS

We performed a cross-sectional comparison of neutrophil functions in 20 antiretroviral-naive HIV-infected and 20 HIV-uninfected individuals using luminescence-, flow cytometry-, and ELISA-based assays. We then conducted a prospective study in the HIV-infected individuals investigating these parameters during the first 6 months of antiretroviral therapy. Surface markers of neutrophil activation were investigated in a separate cohort using flow cytometry.

MEASUREMENTS AND MAIN RESULTS

HIV infection impaired control of Mycobacterium tuberculosis by neutrophils (mean ratio of mycobacterial luminescence in neutrophil samples vs. serum controls at 1 hour in HIV-infected participants, 0.88 ± 0.13 vs. HIV-uninfected participants, 0.76 ± 0.14; P = 0.01; at 24 hours, 0.82 ± 0.13 vs. 0.71 ± 0.13; P = 0.01). The extent of impairment correlated with log[HIV viral load]. Neutrophil cell death after 24 hours' incubation with M. tuberculosis was higher in the HIV-infected cohort (85.3 ± 11.8% vs. 57.9 ± 22.4% necrotic cells; P < 0.0001). Neutrophils from HIV-infected participants demonstrated significantly more CD62L-negative cells (median, 23.0 vs. 8.5%; P = 0.008) and CD16-negative cells (3.2 vs. 1.3%, P = 0.03). Antiretroviral therapy restored mycobacterial restriction and pattern of neutrophil death toward levels seen in HIV-uninfected persons.

CONCLUSIONS

Neutrophils in antiretroviral-naive HIV-infected persons are hyperactivated, eliminate M. tuberculosis less effectively than in HIV-uninfected individuals, and progress rapidly to necrotic cell death. These factors are ameliorated by antiretroviral therapy.

Human Immunodeficiency Virus Infection and Host Defense in the Lungs

Immunosuppression associated with human immunodeficiency virus (HIV) infection impacts all components of host defense against pulmonary infection. Cells within the lung have altered immune function and are important reservoirs for HIV infection. The host immune response to infected lung cells further compromises responses to a secondary pathogenic insult. In the upper respiratory tract, mucociliary function is impaired and there are decreased levels of salivary immunoglobulin A. Host defenses in the lower respiratory tract are controlled by alveolar macrophages, lymphocytes, and polymorphonuclear leukocytes. As HIV infection progresses, lung CD4 T cells are reduced in number causing a lack of activation signals from CD4 T cells and impaired defense by macrophages. CD8 T cells, on the other hand, are increased in number and cause lymphocytic alveolitis. Specific antibody responses by B-lymphocytes are decreased and opsonization of microorganisms is impaired. These observed defects in host defense of the respiratory tract explain the susceptibility of HIV-infected persons for oropharyngeal candidiasis, bacterial pneumonia, Pneumocystis pneumonia, and other opportunistic infections.

Neutrophils Turn Plasma Proteins into Weapons against HIV-1

As a consequence of innate immune activation granulocytes and macrophages produce hypochlorite/hypochlorous acid (HOCl) via secretion of myeloperoxidase (MPO) to the outside of the cells, where HOCl immediately reacts with proteins. Most proteins that become altered by this system do not belong to the invading microorganism but to the host. While there is no doubt that the myeloperoxidase system is capable of directly inactivating HIV-1, we hypothesized that it may have an additional indirect mode of action. We show in this article that HOCl is able to chemically alter proteins and thus turn them into Idea-Ps (Idea-P = immune defence-altered protein), potent amyloid-like and SH-groups capturing antiviral weapons against HIV-1. HOCl-altered plasma proteins (Idea-PP) have the capacity to bind efficiently and with high affinity to the HIV-1 envelope protein gp120, and to its receptor CD4 as well as to the protein disulfide isomerase (PDI). Idea-PP was able to inhibit viral infection and replication in a cell culture system as shown by reduced number of infected cells and of syncytia, resulting in reduction of viral capsid protein p24 in the culture supernatant. The unmodified plasma protein fraction had no effect. HOCl-altered isolated proteins antithrombin III and human serum albumin, taken as representative examples of the whole pool of plasma proteins, were both able to exert the same activity of binding to gp120 and inhibition of viral proliferation. These data offer an opportunity to improve the understanding of the intricacies of host-pathogen interactions and allow the generation of the following hypothetical scheme: natural immune defense mechanisms generate by posttranslational modification of plasma proteins a potent virucidal weapon that immobilizes the virus as well as inhibits viral fusion and thus entry into the host cells. Furthermore simulation of this mechanism in vitro might provide an interesting new therapeutic approach against microorganisms.

Reproductive assistance in HIV serodiscordant couples

BACKGROUND

Three quarters of individuals infected with human immunodeficiency virus (HIV) are in their reproductive years and may consider pregnancy planning. Techniques have been developed which can minimize the risk of HIV transmission in these couples, and the current literature on this topic is reviewed here.

METHODS

We reviewed the literature for the following topics: risk of HIV transmission, effects of HIV infection on fertility, reproductive assistance in industrialized and low-income countries, pre-exposure chemoprophylaxis (PrEP) and timed intercourse in HIV-discordant couples for both male and female positivity. Relevant publications were identified through searches of the EMBASE Medline and PubMed databases, the Google-indexed scientific literature and periodic specialized magazines from the on-line Library Service of the University of Milan, Italy.

RESULTS

In serodiscordant couples in which the man is positive, the primary method used to prevent HIV transmission is 'sperm washing', followed by IUI or IVF. Data show that sperm washing in HIV-positive men has not produced seroconversion in women or their offspring; however, the evidence is limited. Recently, increasing evidence describing PrEP for HIV prevention has been published and PrEP could be an alternative to ART for fertile couples. Usually HIV-infected women undergo self-insemination around the time of ovulation. Few studies have been published on IVF outcome in HIV-infected women.

CONCLUSIONS

Assisted reproduction programmes should be integrated into global public health services against HIV. For HIV serodiscordant couples with infected men, sperm washing should be the first choice. However, timed intercourse and PrEP for HIV prevention has been reported. Recent data highlight the possible impairment of fertility in HIV-infected women. Efforts to design a multicentric study should be strengthened.

Tumour necrosis factor-alpha and interleukin-8 inhibit neutrophil migration in vitro and in vivo

Pretreatment of human neutrophils with recombinant tumour necrosis factor-alpha (rTNF-alpha) and/or interleukin-8 (rIL-8), but not with either transforming growth factor-beta, interleukin-6 or interferon-gamma, rendered these cells less responsive to FMLP, in microchemotaxis assays. This inhibitory effect was dose dependent and more powerful when neutrophils were pretreated with a mixture of both cytokines. Intravenous injection of human rIL-8 (hrIL-8) and/or murine rTNF-alpha (mrTNF-alpha) also significantly reduced in vivo neutrophil migration into peritoneal cavities of rats stimulated with carrageenan. These data suggest that the defect in neutrophil migration during septicaemia or endotoxaemia may be the result of the continuous release of IL-8 and TNF-alpha into the circulation. Thus, either the selective control or blockade of releasing of these cytokines as well as of its effects on neutrophils may be clinically useful in reestablishing the cell defence mechanisms.

HIV infection and aging of the innate immune system

The increased life expectancy of HIV-infected individuals due to improved treatment has revealed an unexpected increase in non-AIDS comorbidities that are typically associated with older age including cardiovascular disease, dementia and frailty. The majority of these diseases arise as the result of dysregulated systemic inflammation, and both the aged and HIV-infected individuals exhibit elevated basal levels of inflammation. In the elderly, increased inflammation and age-related diseases are associated with a state of impaired immunity called immunosenescence, which is thought to result from a lifetime of immune stimulation. It is now apparent that HIV induces premature immunosenescence within T-cells; however, the impact of HIV on aging of cells of the innate arm of the immune system is unknown. Innate immune cells play a central role in inflammation and are thus critical for the pathogenesis of inflammatory diseases. Limited evidence suggests HIV infection mimics age-related changes to innate immune cells; however, the extent of this effect and the mechanism underlying these changes remain to be defined. This review focuses on the impact of HIV infection on the function and aging of innate immune cells and discusses potential drivers of premature immunosenescence including chronic endotoxaemia, residual viraemia, telomere attrition and altered cellular signalling.

Use of Filgrastim (r-metHuG-CSF) in Human Immunodeficiency Virus Infection

In 2008, an estimated 33.4 million individuals worldwide were infected with the human immunodeficiency virus (HIV) [1]. Only a few years ago, infection with HIV almost invariably culminated in the development of the acquired immunodeficiency syndrome (AIDS), characterized by severe depletion of CD4⁺ lymphocytes leading to derangements predominantly affecting cell-mediated immunity, but affecting humoral immunity as well [2]. In the later stages of AIDS, neutropenia and neutrophil functional deficits were common sequelae of HIV infection, other opportunistic infections, or HIV- or opportunistic infection-related treatment [3]. The care of the HIV-infected patient was palliative in nature, and the possibility that use of filgrastim (rHuG-CSF) might extend survival in late-stage AIDS patients with severe neutropenia or severe opportunistic infections, or might be a treatment for HIV infection itself, was explored [4]. Subsequently, however, the development of protease inhibitors and the widespread adoption of their use in multidrug regimens of highly active antiretroviral therapy (HAART) revolutionized the care of HIV-infected patients, and the number of patients dying from HIV decreased dramatically [5].

Impact of macrolide therapy on mortality of HIV-infected patients with community-acquired pneumonia in a tertiary teaching hospital

BACKGROUND

Bacterial pneumonia is one of the main causes of morbidity and mortality in patients infected by the human immunodeficiency virus (HIV). The main objective of this study was to evaluate the effect of macrolide therapy in combination with a beta-lactam based empiric regimen for inpatients with community-acquired pneumonia and HIV.

METHODS

This is a retrospective cohort study of hospitalized patients. Adult patients who had received treatment with ceftriaxone or ceftriaxone plus clarithromycin were included.

RESULTS

76 patients met the inclusion criteria. Among baseline characteristics analyzed, only respiratory rate showed significant difference: patients who had received clarithromycin were more likely to have a respiratory rate > 30/min than patients who received only ceftriaxone (64% versus 36%, p = 0.03). ICU admission was the only outcome that showed a significant difference, more frequent in the ceftriaxone plus clarithromycin group (45% versus 20%, p = 0.03).

CONCLUSIONS

This study does not support the addition of a macrolide to a beta-lactam based regimen in HIV-infected patients. This is probably related to the patients' immunodeficiency status, which impairs the immunomodulatory properties of the macrolides.

Methicillin-resistant Staphylococcus aureus in HIV-infected patients

Concordant with the emergence of methicillin-resistant Staphylococcus aureus (MRSA) in the community setting, colonization and infections with this pathogen have become a prevalent problem among the human immunodeficiency virus (HIV)-positive population. A variety of different host- and, possibly, pathogen-related factors may play a role in explaining the increased prevalence and incidence observed. In this article, we review pathophysiology, epidemiology, clinical manifestations, and treatment of MRSA in the HIV-infected population.

Decreased serum lipocalin-2 levels in human immunodeficiency virus-infected patients: increase during highly active anti-retroviral therapy

Although neutrophil gelatinase-associated lipocalin (NGAL) may play a pivotal role in the innate immune response, there are currently no data on NGAL levels in human immunodeficiency virus (HIV)-infected patients. In this study we aimed to examine the regulation of NGAL in HIV infection. The regulation of NGAL in HIV infection was examined by different experimental approaches, including studies in peripheral blood and mononuclear cells (MNC) from bone marrow aspirates before and during highly active anti-retroviral therapy (HAART). We found that: before initiating HAART, HIV-infected patients (n = 37) had significantly decreased serum NGAL levels compared with healthy controls (n = 26); (ii) during HAART, there was a gradual and significant increase in NGAL concentrations reaching levels comparable to those in healthy controls after 12 months; (iii) this increase was seen primarily in virological responders to HAART (HIV RNA level <200 copies/ml after 24 months); (iv) phytohaemagglutinin-stimulated NGAL release in MNC cells from bone marrow aspirates was decreased in untreated HIV-infected patients compared with healthy controls, but increased after 26 weeks on HAART; and (v) there was a significant positive correlation between neutrophil counts and NGAL levels at all time-points during HAART. We have shown decreased NGAL levels in HIV-infected patients, potentially reflecting decreased number and function of neutrophils as well as impaired bone marrow myelopoiesis. These abnormalities were reversed by successful HAART. Our findings underscore further the involvement of neutrophils and innate immunity in HIV-related immunodeficiency.

Direct effect of human immunodeficiency virus protease inhibitors on neutrophil function and apoptosis via calpain inhibition

Impairment of neutrophil functions and high levels of apoptotic neutrophils have been reported in human immunodeficiency virus (HIV) patients. The aim of the present study was to investigate the direct in vitro effects of the different HIV protease inhibitors (PIs) on neutrophil functions and apoptosis and to explore their mechanisms of action. The effects of nelfinavir (NFV), saquinavir (SQV), lopinavir (LPV), ritonavir (RTV), and amprenavir (APV) in the range of 5 to 100 microg/ml on neutrophil function, apoptosis, and mu-calpain activity were studied. The neutrophil functions studied included superoxide production stimulated by 5 ng/ml phorbol myristate acetate, 5 x 10(-7) M N-formyl-methionyl-leucyl-phenylalanine, and 1 mg/ml opsonized zymosan; specific chemotaxis; random migration; and phagocytosis. Apoptosis was determined by DNA fragmentation, fluorescein isothiocyanate-annexin V binding, and nuclear morphology. All three neutrophil functions, as well as apoptosis, were similarly affected by the PIs. SQV and NFV caused marked inhibition and LPV and RTV caused moderate inhibition, while APV had a minor effect. mu-Calpain activity was not affected by the PIs in neutrophil lysate but was inhibited after its translocation to the membranes after cell stimulation. SQV, which was the most potent inhibitor of neutrophil functions and apoptosis, caused significant inhibition of calpain activity, while APV had no effect. The similar patterns of inhibition of neutrophil functions and apoptosis by the PIs, which coincided with inhibition of calpain activity, suggest the involvement of calpain activity in the regulation of these processes.

Increased interleukin-17 production both in helper T cell subset Th17 and CD4-negative T cells in human immunodeficiency virus infection

Interleukin (IL)-17 is produced mainly by activated CD4(+) T cells, currently known as Th17. Human immunodeficiency virus (HIV) pathogenesis leads to CD4(+) T cell depletion. This is the first report of IL-17 in HIV infection. We assessed IL-17 expression in the CD4(+) T cells (Th17) of 40 asymptomatic HIV-infected treatment-naive patients compared with 40 HIV-seronegative volunteers. Peripheral blood mononuclear cells (PBMCs), with/without phorbol myristate acetate (PMA)/ionomycin stimulation, were stained with CD3, CD4, IL-17, and interferon (IFN)-gamma antibodies and analyzed by four-color flow cytometry. Both groups had comparable baseline data, except for age (mean+/-SD): 36 +/- 9 versus 30 +/- 9 yr (p= 0.001), CD4(+) T cell counts (median): 218 versus 623 cells/microL (p < 0.0001), CD8(+) T cell counts (median): 875.5 versus 382.5 cells/microL ((p) < 0.0001), and CD4(+)/CD8(+) cell ratios (median): 0.225 versus 1.45 (p< 0.0001). Without stimulation, the percentages of IL-17(+) CD3(+) CD4() and IL-17(+) CD3(+) CD4() cells among HIV-seropositive and -seronegative volunteers (median) were as follows: 0.68 versus 0.12% (p< 0.0001) and 0.92 versus 0.09% (p< 0.0001), respectively. With PMA/ionomycin stimulation, the percent IL-17 expression in CD4(+) cells (median) was 1.45 versus 0.65 (p< 0.0001) and in CD4() T cells it was 1.0 versus 0.12 (p< 0.0001). In conclusion, HIV infection is associated with a significant increase in IL-17 production in both CD4(+) and CD4() T cells in peripheral blood. IL-17 expression was further inducible by PMA/ionomycin stimulation in vitro only in CD4(+) T cells. The roles of IL-17 and Th17 in HIV viral replication and immunopathogenesis are under further investigation.

Community-associated methicillin-resistant Staphylococcus aureus in the patient with HIV infection

The prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increased alarmingly in both the general population and the HIV-infected community. We look at the background of MRSA including the mechanisms of resistance, genetics, and trends in the individual with HIV infection. Numerous studies have investigated the risk factors for CA-MRSA. Other studies have further characterized the incidence of and risk factors for MRSA infections in the HIV community. Although one might not readily associate advanced HIV infection with increased susceptibility to bacterial pathogens, a number of studies have explained the mechanisms of this B-cell-mediated susceptibility. Invasive MRSA infections have spread into communities, are increasingly prevalent, and pose a public health challenge for their containment, prevention, and treatment.

CD8+ T cells but not polymorphonuclear leukocytes are required to limit chronic oral carriage of Candida albicans in transgenic mice expressing human immunodeficiency virus type 1

Candida albicans causes oropharyngeal candidiasis (OPC) but rarely disseminates to deep organs in human immunodeficiency virus (HIV) infection. Here, we used a model of OPC in CD4C/HIV(Mut) transgenic (Tg) mice to investigate the role of polymorphonuclear leukocytes (PMNs) and CD8+ T cells in limiting candidiasis to the mucosa. Numbers of circulating PMNs and their oxidative burst were both augmented in CD4C/HIV(MutA) Tg mice expressing rev, env, and nef of HIV type 1 (HIV-1), while phagocytosis and killing of C. albicans were largely unimpaired compared to those in non-Tg mice. Depletion of PMNs in these Tg mice did not alter oral or gastrointestinal burdens of C. albicans or cause systemic dissemination. However, oral burdens of C. albicans were increased in CD4C/HIV(MutG) Tg mice expressing only the nef gene of HIV-1 and bred on a CD8 gene-deficient background (CD8-/-), compared to control or heterozygous CD8+/- CD4C/HIV(MutG) Tg mice. Thus, CD8+ T cells contribute to the host defense against oral candidiasis in vivo, specifically in the context of nef expression in a subset of immune cells.

Longitudinal Evaluation of Loss of Attachment in HIV-Infected Women Compared to HIV-Uninfected Women

BACKGROUND

The Women's Interagency HIV Study (WIHS) is the largest, most detailed, controlled longitudinal collection of data to evaluate the influence of human immunodeficiency virus (HIV) disease and its therapies on the periodontium.

METHODS

This report evaluates periodontal probing depth (PD), attachment loss (AL), and tooth loss from 584 HIV-seropositive and 151 HIV-seronegative women, recorded at 6-month intervals from 1995 to 2002. Using the random split-mouth method, PD and AL were recorded from four sites per tooth: mesial-buccal, buccal, distal-buccal, and lingual. Influence of viral load, CD4 count, race, smoking, drug use, low income, and level of education were evaluated.

RESULTS

At baseline, AL was 1.6 versus 1.1 mm (P = 0.003) and PD was marginally deeper (2.1 versus 2.0 mm; P = 0.02) in HIV-seropositive versus HIV-seronegative women. Adjusted longitudinal analysis showed that HIV infection did not increase the mean PD (rate ratio [RR], 1.00; 95% confidence interval [CI], 0.96 to 1.04), worst PD (RR, 1.03; 95% CI, 0.98 to 1.09), mean AL (RR, 0.97; 95% CI, 0.96 to 1.02), worst AL (RR, 1.01; 95% CI, 0.94 to 1.07), or tooth loss (RR, 1.02; 95% CI, 1.0 to 1.05).

CONCLUSIONS

CD4 count and viral load had no consistent effects on PD or AL. Among HIV-infected women, a 10-fold increase in viral load was associated with a marginal increase in tooth loss. The progression of periodontal disease measured by PD and AL did not significantly differ between HIV-infected and HIV-uninfected women. The HIV-seropositive women lost more teeth. Race, smoking, drug use, income, and education level did not influence the results for either group.

Inhibition of neutrophil function by the Kaposi's sarcoma-associated herpesvirus vOX2 protein

Kaposi's sarcoma is multifactorial, involving Kaposi's sarcoma-associated herpesvirus (KSHV) infection and immune dysfunction. A KSHV protein (vOX2), fused with the Fc domain of human immunoglobulin G1 to create vOX2:Fc, suppressed neutrophil oxidative burst and inhibited the production of pro-inflammatory chemokines (IL-8 and monocyte chemoattractant protein 1) by monocyte/macrophage cells. vOX2:Fc suppressed the acute inflammatory response in mice in which neutrophil-mediated inflammation was induced by carrageenan. The data suggest that vOX2 can contribute to immune dysfunction and could have anti-inflammatory therapeutic potential.

Quantitative and qualitative antibody response to pneumococcal conjugate vaccine among African human immunodeficiency virus-infected and uninfected children

OBJECTIVE

To determine the quantitative and qualitative antibody responses to a pneumococcal conjugate vaccine (PnCV) in human immunodeficiency virus (HIV)-exposed infected and uninfected children.

METHODS

Children were randomized to receive either a PnCV or placebo at 6, 10 and 14 weeks of age. PnCV serotype-specific antibody concentrations were measured by a standard enzyme immunoassay (EIA) and a 22F modified EIA (22F EIA) on single serum samples drawn at 21-42 days post-dose 3. Functional activities of the serotype-specific antibody to serotypes 6B, 19F and 23F were measured with an opsonophagocytic assay (OPA).

RESULTS

The geometric mean antibody concentrations (GMC) were similar in HIV-infected and HIV-uninfected PnCV recipients for 7 of the 9 vaccine serotypes. In placebo recipients, the GMCs were significantly higher in HIV-infected than in uninfected children for 7 of the serotypes. In HIV-infected PnCV recipients, the GMCs were lower for 5 of the serotypes in children with severe acquired immunodeficiency syndrome than in children who were asymptomatic or mildly symptomatic with acquired immunodeficiency syndrome. HIV-infected PnCV recipients were less likely to have measurable functional antibody (OPA titer > or =1/8) to all 3 studied serotypes (6B, 19F and 23F) than in HIV-uninfected children. HIV-infected children required a higher concentration of anticapsular antibody to achieve 50% of the maximum uptake of labeled Streptococcus pneumoniae in the OPA assay than HIV-uninfected children for 2 of the 3 serotypes, although this was significant only for serotype 6B (P = 0.0005).

CONCLUSION

HIV-infected children have similar quantitative antibody responses but poorer qualitative antibody responses to the PnCV.

Influence of HIV-infection on the phagocytic activity of monocytes/macrophages and granulocytes

Because of the great importance of phagocytosis as a key process in host defence, the influence of HIV-infection on the phagocytic activity of monocytes/macrophages (M0/MAC) and granulocytes was investigated. Therefore, blood samples from the peripheral blood of 70 HIV-infected individuals were incubated with fluorescein isothiocyanate (FITC) labeled Escherichia coli. The uptake of the bacteria was monitored by flow cytometer analysis. A strong and significant increase in the relative number of phagocytic granulocytes was observed ranging from 12.8% in an uninfected control collective to over 30% in AIDS patients. This effect was obtained for all patients and independent of the stage of disease. For monocytes, only marginal changes were found in their phagocytic function. These data suggest that the high susceptibility of HIV patients for secondary infections is not linked to a loss of phagocytic ability of monocytes/macrophages and/or granulocytes.

Immunopathogenesis of oropharyngeal candidiasis in human immunodeficiency virus infection

Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4(+) cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8(+) T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.

Increased Fas-mediated apoptosis in polymorphonuclear cells from HIV-infected patients

Neutrophils represent an important line of innate host defence against invading microorganisms and their functional detriment during HIV infection, including accelerated spontaneous cell death, has been shown to contribute to AIDS development. Neutrophils are susceptible to apoptosis via Fas and an interaction between Fas and FasL was suggested originally as a mechanism to explain constitutive neutrophil apoptosis. We have explored some intracellular pathways leading to PMN apoptosis from 28 HIV-infected patients and 24 healthy volunteers. As previously reported, accelerated spontaneous apoptosis was observed in HIV+ patients, but this did not correlate with viral load. Furthermore, an increase in the level of spontaneous apoptosis was detected in neutrophils from HIV-infected patients following inhibition of ERK, suggesting an impairment of this kinase pathway during the early stages of infection which may contribute to PMN dysfunction. An elevated susceptibility to undergo apoptosis was observed following cross-linking of Fas, which correlated both with viral load and co-expression of Fas/FasL surface molecules. Different mechanisms for spontaneous and Fas-induced apoptosis are proposed which together contribute to the neutropenia and secondary infections observed during the progression to AIDS.

Decreased serum opsonic activity against Streptococcus pneumoniae in human immunodeficiency virus-infected Ugandan adults

Type-specific immunoglobulin G (IgG) to pneumococcal capsular polysaccharide (CPS) and opsonic activity against Streptococcus pneumoniae were evaluated in serum samples from 36 Ugandan adults with community-acquired pneumonia and 58 asymptomatic Ugandan adults with or without human immunodeficiency virus type 1 (HIV-1) infection. The levels of serum IgG to CPS were significantly higher in HIV-1-infected subjects than in HIV-uninfected subjects. Serum samples from HIV-1-infected subjects that had lower IgG titers demonstrated higher opsonic activity against type 3 (titers of 7) and type 9 (titers of 7-11) pneumococcal strains. Plasma HIV-1 load also correlated inversely with serum opsonic activity against these strains, and peripheral blood CD4+ lymphocyte numbers also tended to correlate with serum opsonic activity in asymptomatic HIV-1-infected adults. Our findings suggest that the opsonic activity of type-specific IgG is impaired in the serum of HIV-1-infected African adults, which may expose them to a serious risk of invasive pneumococcal infections.

Etiology of persistent tubo-ovarian abscess in Nairobi, Kenya

OBJECTIVE

To study the microbial etiology of tubo-ovarian abscess (TOA).

METHODS

We recruited 11 women in Nairobi, Kenya who failed antibiotic therapy alone and required surgical drainage of a presumptive TOA. Pus from the nine abscesses and two pyosalpinges were collected and cultured for aerobic, facultative and anaerobic microorganisms.

RESULTS

Eleven women suspected of having a TOA were hospitalized and treated for a median of 6 days (range 3-14 days) prior to surgical drainage of the abscess. Nine (82%) specimens were culture positive. Aerobes were present in all nine specimens. Seven of the nine positive cultures (78%) were polymicrobial and five of the polymicrobial cultures contained both anaerobes and aerobes. Anaerobic Gram-negative bacilli (Prevotella sp., Porphyromonas sp. and Bacteroides sp., Escherichia coli) and Streptococcus sp. (S. viridans and S. agalactiae) were the most common microorganisms isolated. Neisseria gonorrhoeae and Chlamydia trachomatis were not isolated by culture or detected by polymerase chain reaction.

CONCLUSIONS

In Kenya, persistent TOAs are associated with endogenous flora similar to that normally found in the gastrointestinal tract.

Botryomycosis in an HIV-positive subject

A 28-year-old male AIDS patient with generalized painful skin ulcers, fever and malaise presented to us. The differential diagnosis included varicella zoster infection, herpes simplex infection, actinomycosis, sporotrichosis and botryomycosis. Histopathology revealed clusters of gram-positive coccoid bacteria in the deep dermis, surrounded by a mixed dense inflammatory infiltrate. A bacterial culture grew Staphylococcus aureus. Viral cultures remained negative. Based on these findings botryomycosis was diagnosed. Large lesions were excised surgically and with antimicrobial therapy all skin symptoms disappeared. We discuss this case with reference to a short review of the literature on botryomycosis in relation to HIV infection.

IgG subclass specific antibody response to periodontopathic organisms in HIV-positive patients

BACKGROUND

We previously reported an increased rate of progression of periodontal disease over an 18-month period in human immunodeficiency virus (HIV)-positive subjects compared to controls. The mechanism for disease progression and rapid tissue loss was unknown. Data on the microbiological studies failed to show any significant difference in the microbial characteristics of the periodontal lesions in HIV-positive patients compared to HIV-negative controls. Immunological analysis had identified neutrophils as an important component of the host defense against periodontal infection, especially against rapid tissue loss. Serum IgG reactivities to periodontal pathogens in HIV-positive patients with periodontitis were reduced. Other data provided circumstantial evidence to suggest that IgG subclass (IgG2) specific antibody might assist bacterial clearing in periodontal infection. The aim of the current study was to examine the specific IgG subclass antibody response to a panel of periodontopathic organisms: Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella Intermedia (Pi), Fusobacterium nucleatum (Fn), Campylobacter rectus (Cr), and Bacteroides forsythus (Bf) in HIV-positive patients compared to HIV-negative controls.

METHODS

Sera from 120 HIV-positive patients (40 periodontitis, 69 gingivitis, and 11 no oral diseases) were tested for IgG subclass specific antibody response to the above listed 6 organisms using enzyme-linked immunosorbent assay. Data were compared with those obtained from 40 HIV-negative control subjects (35 periodontitis, 2 gingivitis, and 3 no oral diseases).

RESULTS

In the HIV-positive group, a consistently high response rate was found in IgG1 to all the bacteria tested. In addition, high levels of IgG3 and IgG4 to Pg and IgG1 and IgG2 to Pi were also present. However, no significant difference was detected among the periodontitis, gingivitis, and no oral disease subgroups. When the periodontitis patients from the HIV-positive group were compared to the HIV-negative group, no difference in the antibody levels and response rates was noted.

CONCLUSION

We conclude that in HIV-positive patients, the specific IgG subclass antibody response to periodontopathic organisms was similar to that of HIV-negative subjects.

Iron overload exacerbates experimental meningoencephalitis by Cryptococcus neoformans

This study was aimed at investigating the effects of iron overload on the onset and outcome of cerebral cryptococcosis. To this purpose, iron dextran-administered mice were intracerebrally challenged with virulent melanogenic and avirulent non-melanogenic strains of Cryptococcus neoformans. The results shown here provide the first evidence that iron overload exacerbates the outcome of cryptococcal meningoencephalitis, irrespective of the fungal strain employed; pathogen colonization of the brain is facilitated, local cytokine response is delayed and/or prevented.

HIV-1 envelope gp41 peptides promote migration of human Fc epsilon RI+ cells and inhibit IL-13 synthesis through interaction with formyl peptide receptors

We evaluated the effects of synthetic peptides (2017, 2019, 2020, 2021, 2023, 2027, 2029, 2030, 2031, and 2035) encompassing the structure of HIV-1(MN) envelope gp41 on both chemotaxis of human basophils and the release of preformed mediators (histamine) and of cytokines (IL-13). Peptides 2019 and 2021 were potent basophil chemoattractants, whereas the other peptides examined were ineffective. Preincubation of basophils with FMLP or gp41 2019 resulted in complete desensitization to a subsequent challenge with homologous stimulus. Incubation of basophils with low concentration (5 x 10(-7) M) of FMLP, which binds with high affinity to N-formyl peptide receptor (FPR), but not to FPR-like 1, did not affect the chemotactic response to a heterologous stimulus (gp41 2019). In contrast, a high concentration (10(-4) M) of FMLP, which binds also to FPR-like 1, significantly reduced the chemotactic response to gp41 2019. The FPR antagonist cyclosporin H inhibited chemotaxis induced by FMLP, but not by gp41 2019. None of these peptides singly induced the release of histamine or cytokines (IL-4 and IL-13) from basophils. However, low concentrations of peptides 2019 and 2021 (10(-8)-10(-6) M) inhibited histamine release from basophils challenged with FMLP but not the secretion caused by anti-IgE and gp120. Preincubation of basophils with peptides 2019 and 2021 inhibited the expression of both IL-13 mRNA, and the FMLP-induced release of IL-13 from basophils. These data highlight the complexity of the interactions between viral and bacterial peptides with FPR subtypes on human basophils.

Impaired macrophage phagocytosis of apoptotic neutrophils in patients with human immunodeficiency virus type 1 infection

Dysfunction of neutrophils (polymorphonuclear leukocytes [PMNL]) and macrophagic cells occurs as a consequence of human immunodeficiency virus type 1 (HIV-1) infection. Macrophages contribute to the resolution of early inflammation ingesting PMNL apoptotic bodies. This study investigated macrophage ability to phagocytose PMNL apoptotic bodies in patients with HIV-1 infection in comparison with uninfected individuals and the effect of HIV Nef protein on apoptotic body phagocytosis to determine if phagocytic activity is impaired by HIV infection. Monocytes/macrophages were isolated from 10 HIV-1-infected patients and from five healthy volunteers, whereas PMNL were isolated from healthy volunteers. Macrophage phagocytosis of apoptotic PMNL was determined by staining of apoptotic bodies with fluorescein-conjugated concanavalin A or with fluorescein-labeled phalloidin. Our data show significant impairment of PMNL apoptotic body macrophage phagocytosis in subjects with HIV-1 infection presenting a concentration of CD4(+) T lymphocytes of >200/mm(3) and in particular in those with <200 CD4(+) T lymphocyte cells/mm(3). In addition, HIV-1 recombinant Nef protein is able to decrease phagocytosis of apoptotic PMNL from normal human macrophages in a dose-dependent manner. The results of our study suggest that impaired macrophage phagocytosis of PMNL apoptotic bodies may contribute to the persistence of the inflammatory state in HIV-infected subjects, especially during opportunistic infections that are often favored by defective phagocytic activity.

Involvement of NO in the failure of neutrophil migration in sepsis induced by Staphylococcus aureus

1. Sepsis induced by S. aureus was used to investigate whether neutrophil migration failure to infectious focus correlates with lethality in Gram-positive bacteria-induced sepsis in mice. 2. By contrast with the sub-lethal (SL-group), the lethal (L-group) intraperitoneal inoculum of S. aureus caused failure of neutrophil migration (92% reduction), high CFU in the exudate, bacteremia and impairment of in vitro neutrophil chemotactic activity. 3. Pre-treatments of L-group with adequate doses of aminoguanidine prevented the neutrophil migration failure and improved the survival of the animals (pre-treated: 43%; untreated: 0% survival). Thus, the impairment of neutrophil migration in the L-group appears to be mediated by nitric oxide (NO). 4. The injection of S. aureus SL-inoculum in iNOS deficient (-/-) or aminoguanidine-treated wild-type mice (pre- and post-treatment), which did not present neutrophil migration failure, paradoxically caused severe peritonitis and high mortality. This fact is explainable by the lack of NO dependent microbicidal activity in migrated neutrophils. 5. In conclusion, although the NO microbicidal mechanism is active in neutrophils, the failure of their migration to the infectious focus may be responsible for the severity and outcome of sepsis.

Inhibition of leukocyte rolling by nitric oxide during sepsis leads to reduced migration of active microbicidal neutrophils

We developed two models of sepsis with different degrees of severity, sublethal and lethal sepsis, induced by cecal ligation and puncture. Lethal sepsis induced by cecal ligation and puncture (L-CLP) resulted in failure of neutrophil migration to the infection site and high mortality. Treatment of septic animals with aminoguanidine (AG), a nitric oxide (NO) synthase inhibitor, precluded the failure of neutrophil migration and protected the animals from death. However, cytokine-induced NO synthase (iNOS)-deficient (iNOS(-/-)) mice subjected to L-CLP did not present neutrophil migration failure, but 100% lethality occurred. iNOS(-/-) mice subjected to sublethal sepsis induced by cecal ligation and puncture (SL-CLP) also suffered high mortality despite the occurrence of neutrophil migration. This apparent paradox could be explained by the lack of microbicidal activity in neutrophils of iNOS(-/-) mice present at the infection site due to their inability to produce NO. Notably, SL- and L-CLP iNOS(-/-) mice showed high bacterial numbers in exudates. The inhibition of neutrophil migration by NO is due to inhibition of a neutrophil/endothelium adhesion mechanism, since a reduction in leukocyte rolling, adhesion, and emigration was observed in L-CLP wild-type mice. These responses were prevented by AG treatment and were not observed in the iNOS(-/-) L-CLP group. There was no significant change in L-selectin expression in neutrophils from L-CLP mice. Thus, it seems that the decrease in leukocyte rolling is due to a defect in the expression of adhesion molecules on endothelial surfaces mediated by iNOS-derived NO. In conclusion, the results indicate that despite the importance of NO in neutrophil microbicidal activity, its generation in severe sepsis reduces neutrophil migration by inhibiting leukocyte rolling and their firm adhesion to the endothelium, in effect impairing the migration of leukocytes and consequently their fundamental role in host cell defense mechanisms.

An evaluation of antiretroviral therapy associated with alpha-tocopherol supplementation in HIV-infected patients

In HIV-infected patients, an increase in the production of oxygen-reactive species (ROS) is observed, with a consequent reduction of plasma levels of antioxidants such as alpha-tocopherol. The nuclear transcription factor-kappaB (NF-kappaB) is activated by a prooxidant state in the infected T cells through the release of its inhibitory subunit I-kappaB. The aim of the present work was to evaluate the behavior of hematological parameters and markers of anemia in HIV-infected patients who underwent antiretroviral therapy associated with 800 mg/day alpha-tocopherol supplementation. Blood samples were collected from supplemented (n=9) and not-supplemented (n=9) HIV-seropositive patients (n=18). We observed a decreased viral load in the alpha-tocopherol-supplemented group (p<0.05); other changes, such as an increase in the CD4/CD8 ratio, in the hematocrit and in the hemoglobin concentration were also observed, though lacking statistical significance. We conclude that antiretroviral therapy in association with alpha-tocopherol (800 mg/day) supplementation is more effective in reducing viral load levels and also, possibly, in recovering other hematological parameters after a 60-day period of use.

Fungemia in HIV-infected patients: a 12-year study in a tertiary care hospital

Opportunistic infections caused by fungi are common in human immunodeficiency virus (HIV)-infected patients. We focused on severe infections as indicated by detectable fungemia. Medical charts available for patients having positive blood cultures with fungi at the University of Geneva Hospital were retrospectively (1989 to 2000) reviewed. Of 328 patients with fungemia during the study period, 315 (96%) medical charts were accessible. Of these 315 patients, 37 (12.2%) were HIV-positive, and 13 (35.1%) died within 6 months from their episode of fungemia. This was a lower mortality rate than for the HIV seronegative patients (45.8%). The median and average age of the 34 HIV-positive patients was 37.2 years, and 24 (64.9%) were males. Cryptococcus neoformans (n = 14) and Candida albicans (n = 12) were the most frequently identified species, followed by Candida glabrata (n = 3), of which 3 were mixed C. albicans + C. glabrata, Histoplasma capsulatum (n = 2), and Penicillium marneffei (n = 2). The frequency decreased significantly (p < 0.007) from the time period 1993 to 1996 (n = 21) to the period 1997 to 2000 (n = 6). Fungemias in HIV-infected patients have declined significantly since 1996. This coincides with the introduction of highly active antiretroviral therapy (HAART).

Infective endocarditis in patients with human immunodeficiency virus infection

OBJECTIVES

To determine the clinical features, sites of involvement, bacteriological findings, and outcome of infective endocarditis (IE) in patients with HIV infection.

PATIENTS AND METHODS

All patients with diagnosis of IE admitted to 54 infectious disease centres in Italy over a 15-year period (1984-1999) were reviewed, and 895 cases fulfilled the Duke criteria for definite diagnosis of IE. Data were collected with regard to the clinical, laboratory, and demographic characteristics of patients, as well as results of blood cultures and data on clinical outcome.

RESULTS

There were 108 episodes of IE in 105 HIV-infected patients. The mean age of patients was 30.1 years, and the commonest predisposing condition was intravenous drug use (94.3%). Staphylococci were the predominant organisms (60.2%), and the tricuspid valve was the most frequently involved site of infection (51.9%). Left-sided heart involvement (45.4%) and multivalvular involvement (17.6%) were also frequently observed. The greater frequency of S. aureus affecting the tricuspid valve vs. other valves was statistically significant (P<0.001). Six patients (5.9%) underwent surgery, and one (16.7%) of them died. Ninety-five (94.1%) patients were treated medically, and 17 (17.9%) of them died. Overall mortality rate was 17.8%. Any left-sided heart involvement was predictive of an increased risk of death if compared with any right-sided heart involvement (P< 0.004). The mortality rate among HIV-infected patients was higher in those with CD4 cell counts below 200/mm(3).

CONCLUSIONS

IE in HIV-infected patients, for the most part intravenous drug users, is more commonly localized to the right side of the heart; however, mixed or left-side valvular infections are frequent. Severe immunosuppression and left-side valvular involvement are associated with a greater risk for mortality.

Management of complications associated with totally implantable ports in patients with AIDS

Morbidity associated with totally implantable ports is common in patients with acquired immune deficiency syndrome (AIDS). More than half of the implanted devices will have at least one complication before its removal or the patient's death. Infectious complications are the most frequent. Two patients are reported here in whom staphylococcal infection of the totally implantable port occurred; one of the devices could be saved through the antibiotic lock technique. Infectious complications of totally implantable ports occur more commonly in patients who are neutropenic or who have low CD4 cell counts (<25 cells per microliter). When patients have chamber infection (the most frequent infectious complication) with or without secondary bacteremia, the antibiotic lock technique has proven useful for device sterilization.

Defective neutrophil degranulation induced by interleukin-8 and complement 5a and down-regulation of associated receptors in children vertically infected with human immunodeficiency virus type 1

The polymorphonuclear neutrophils (PMNs) of patients infected with human immunodeficiency virus type 1 (HIV-1) show impaired microbicidal responses. The present study assessed the functional integrity of PMN degranulation responses and the expression of specific receptors that mediate these responses in a group of children vertically infected with HIV-1. PMN degranulation in response to interleukin-8 (IL-8) and complement 5a (C5a) was measured in a group of HIV-1-infected children with mild and severe clinical disease and in an uninfected control group. In addition, the expression of CXCR1, CXCR2, and CD88 on whole-blood PMNs was quantified by flow cytometry. Although CXCR1 expression was found to be largely unaltered in the HIV-1-infected children relative to that in the control children, the intensity of CXCR2 expression was significantly reduced in those with severe disease. Furthermore, there was a significant reduction in the percentage of cells expressing CD88 and in the intensity of CD88 fluorescence in the HIV-1-infected children compared to that in control children, with CD88 fluorescence intensity more significantly reduced in the presence of severe disease. PMNs from a large proportion of the HIV-1-infected children either showed reciprocal degranulation responses or were unresponsive to IL-8 and C5a, whereas the PMNs from the uninfected children showed positive responses. Inefficient agonist-induced degranulation may contribute to the increased susceptibility of HIV-1-infected children to secondary microbial infections. Furthermore, reduced expression of CXCR2 and CD88 may be suggestive of defects in other functions of PMNs from HIV-1-infected children.

N36, a synthetic N-terminal heptad repeat domain of the HIV-1 envelope protein gp41, is an activator of human phagocytes

Human immunodeficiency virus type 1 (HIV-1) envelope protein gp41 mediates viral fusion with human host cells. In this study we show that N36, a synthetic peptide derived from the N-terminus of gp41, induced directional migration and calcium mobilization in human monocytes and neutrophils. The activity of N36 on phagocytes was pertussis toxin sensitive, suggesting involvement of a Gi-coupled seven-transmembrane receptor(s). Since high concentrations of the bacterial chemotactic peptide fMet-Leu-Phe (fMLF) partially desensitized the calcium mobilizing activity of N36 in phagocytes, we postulated that N36 might use a low-affinity fMLF receptor. By using cells stably expressing fMLF receptor FPR or FPRL1, we demonstrate that N36 uses FPRL1 as a functional receptor. Our results suggest that HIV-1 gp41 may contain a fragment(s) that activates the innate host immune cells through FPRL1. Since the activation of FPRL1 in monocytes has been shown to heterologously desensitize chemokine receptors, the reduced phagocyte response to chemoattractants seen in AIDS patients may be attributed, at least in part, to heterologous desensitization.

Interleukin-15 enhances neutrophil functional activity in patients with human immunodeficiency virus infection

Polymorphonuclear leukocyte (PMN) dysfunction has been reported in human immunodeficiency virus (HIV)-infected patients. Interleukin (IL)-15 is a recently discovered cytokine that potentiates antimicrobial functions of normal PMNs. We evaluated the in vitro effect of IL-15 on chemotaxis and fungicidal activity of PMNs from 9 patients with untreated advanced HIV infection, 8 patients with viral suppression after 52 to 130 weeks of highly active antiretroviral therapy (HAART), and 12 patients with treatment failure. We also studied oxidative burst and apoptosis of PMNs in 5 patients with untreated advanced HIV infection. Twelve healthy donors were included as controls. Chemotaxis and fungicidal activity of unprimed PMNs was significantly lower in patients with untreated HIV infection compared with controls. After incubation with IL-15, a significant increase in PMN chemotaxis and fungicidal activity was found; moreover, IL-15 induced a significant reduction in the number of apoptotic HIV+ PMNs. IL-15 did not modulate oxidative burst of HIV+ PMNs as measured by chemiluminescence production. The in vitro priming of PMNs with IL-15 determined a complete reversal of defective chemotaxis and killing in all HAART-treated patients with long-term HIV suppression. IL-15 significantly enhanced chemotaxis and fungicidal activity also in patients with HAART failure. In conclusion, IL-15 is an important cytokine in the activation of the functional properties of HIV+ PMNs, by delaying apoptosis and enhancing chemotaxis and fungicidal activity. The potent stimulant effect of IL-15 on PMN function was observed in antiretroviral naive patients as well as in individuals who were receiving HAART, including those with treatment failure.