Infection of cord blood monocyte-derived macrophages with human immunodeficiency virus type 1

Activation of Toll-like receptor 3 inhibits HIV infection of human iPSC-derived microglia

As a key immune cell in the brain, microglia are essential for protecting the central nervous system (CNS) from viral infections, including HIV. Microglia possess functional Toll-like receptor 3 (TLR3), a key viral sensor for activating interferon (IFN) signaling pathway-mediated antiviral immunity. We, therefore, studied the effect of poly (I:C), a synthetic ligand of TLR3, on the activation of the intracellular innate immunity against HIV in human iPSC-derived microglia (iMg). We found that poly (I:C) treatment of iMg effectively inhibits HIV infection/replication at both mRNA and protein levels. Investigations of the mechanisms revealed that TLR3 activation of iMg by poly (I:C) induced the expression of both type I and type III IFNs. Compared with untreated cells, the poly (I:C)-treated iMg expressed significantly higher levels of IFN-stimulated genes (ISGs) with known anti-HIV activities (ISG15, MxB, Viperin, MxA, and OAS-1). In addition, TLR3 activation elicited the expression of the HIV entry coreceptor CCR5 ligands (CC chemokines) in iMg. Furthermore, the transcriptional profile analysis showed that poly (I:C)-treated cells had the upregulated IFN signaling genes (ISG15, ISG20, IFITM1, IFITM2, IFITM3, IFITM10, APOBEC3A, OAS-2, MxA, and MxB) and the increased CC chemokine signaling genes (CCL1, CCL2, CCL3, CCL4, and CCL15). These observations indicate that TLR3 is a potential therapy target for activating the intracellular innate immunity against HIV infection/replication in human microglial cells. Therefore, further studies with animal models and clinical specimens are necessary to determine the role of TLR3 activation-driven antiviral response in the control and elimination of HIV in infected host cells.

Antiviral Response Induced by TLR7/TLR8 Activation Inhibits HIV-1 Infection in Cord Blood Macrophages

Vertical transmission is the main mechanism of HIV-1 infection in infants, who may develop high viremia and rapidly progress to AIDS. Innate immunity agonists can control HIV-1 replication in vitro, but the protective effect in the neonatal period remains unknown. Herein, we evaluated the immunomodulatory and antiviral effects of IFN-I adjuvants on cord blood monocyte-derived macrophages upon HIV-1 infection. Despite the phenotypic and transcriptional similarities between cord blood and adult macrophages, cord blood cells were prone to viral replication when infected with HIV-1. However, treatment with CL097 efficiently promoted the antiviral and inflammatory responses and inhibited HIV-1 replication in cord blood cells in an NF-κB and autophagy activation-independent manner. Our data suggest that cord blood macrophages are able to establish antiviral responses induced by IFN-I adjuvants similar to those of their adult counterparts, revealing a potential adjuvant candidate to enhance the neonatal immune response.

The Warburg Effect Occurs Rapidly in Stimulated Human Adult but Not Umbilical Cord Blood Derived Macrophages

The Warburg effect, defined as increased glycolysis and decreased oxidative phosphorylation, occurs in murine macrophages following LPS stimulation and is required for activation. There are differences between human and murine macrophage metabolic responses to stimulation, with peak metabolite concentrations occurring earlier in humans than mice. Complex changes occur in the human immune system with age, resulting in the very young and the very old being more susceptible to infections. Anti-bacterial immune responses in umbilical cord immune cells are considered deficient but there is a paucity of data on the role that metabolism plays. We hypothesized that metabolic responses in human macrophages occur early during activation. In addition, we hypothesized that umbilical cord derived macrophages have an altered immunometabolic response compared with adult macrophages. We demonstrate that adult and cord blood monocyte derived macrophages (MDM) immediately increase glycolysis in response to stimulation with LPS or Mycobacterium tuberculosis (Mtb), however only adult MDM decrease oxidative phosphorylation. At 24 hours post stimulation, glycolysis remains elevated in both adult and cord blood MDM, oxidative phosphorylation remains unchanged in the cord blood MDM and has normalized in the adult MDM stimulated with Mtb. However, LPS stimulated adult MDM have increased oxidative phosphorylation at 24 hours, illustrating differences in metabolic responses to different stimuli, time-dependent variation in responses and differences in macrophage metabolism in adults compared with umbilical cord blood. We compared the phenotype and function of macrophages derived from adult or cord blood. Cord blood MDM secreted less TNF following Mtb stimulation and more IL-6 following LPS stimulation compared with adult MDM. Our findings demonstrate that whilst cord blood MDM exhibit an immediate increase in glycolytic flux in response to stimulation, similar to adult MDM, cord blood MDM do not concomitantly decrease oxygen consumption. This indicates that adult macrophages shift to Warburg metabolism immediately after stimulation, but cord blood macrophages do not. Understanding the differences in the metabolic profiles of macrophages over a human lifetime will enable the translation of immunometabolism into effective immuno-supportive therapies that could potentially be targeted at vulnerable populations, such as the very old and the very young.

Critical Role for Monocytes/Macrophages in Rapid Progression to AIDS in Pediatric Simian Immunodeficiency Virus-Infected Rhesus Macaques

Infant humans and rhesus macaques infected with the human or simian immunodeficiency virus (HIV or SIV), respectively, express higher viral loads and progress more rapidly to AIDS than infected adults. Activated memory CD4+ T cells in intestinal tissues are major primary target cells for SIV/HIV infection, and massive depletion of these cells is considered a major cause of immunodeficiency. Monocytes and macrophages are important cells of innate immunity and also are targets of HIV/SIV infection. We reported previously that a high peripheral blood monocyte turnover rate was predictive for the onset of disease progression to AIDS in SIV-infected adult macaques. The purpose of this study was to determine if earlier or higher infection of monocytes/macrophages contributes to the more rapid progression to AIDS in infants. We observed that uninfected infant rhesus macaques exhibited higher physiologic baseline monocyte turnover than adults. Early after SIV infection, the monocyte turnover further increased, and it remained high during progression to AIDS. A high percentage of terminal deoxynucleotidyltransferase dUTP nick end label (TUNEL)-positive macrophages in the lymph nodes (LNs) and intestine corresponded with an increasing number of macrophages derived from circulating monocytes (bromodeoxyuridine positive [BrdU+] CD163+), suggesting that the increased blood monocyte turnover was required to rapidly replenish destroyed tissue macrophages. Immunofluorescence analysis further demonstrated that macrophages were a significant portion of the virus-producing cells found in LNs, intestinal tissues, and lungs. The higher baseline monocyte turnover in infant macaques and subsequent macrophage damage by SIV infection may help explain the basis of more rapid disease progression to AIDS in infants.IMPORTANCE HIV infection progresses much more rapidly in pediatric cases than in adults; however, the mechanism for this difference is unclear. Using the rhesus macaque model, this work was performed to address why infants infected with SIV progress more quickly to AIDS than do adults. Earlier we reported that in adult rhesus macaques, increasing monocyte turnover reflected tissue macrophage damage by SIV and was predictive of terminal disease progression to AIDS. Here we report that uninfected infant rhesus macaques exhibited a higher physiological baseline monocyte turnover rate than adults. Furthermore, once infected with SIV, infants displayed further increased monocyte turnover that may have facilitated the accelerated progression to AIDS. These results support a role for monocytes and macrophages in the pathogenesis of SIV/HIV and begin to explain why infants are more prone to rapid disease progression.

IFN-λ Inhibits Drug-Resistant HIV Infection of Macrophages

Type III interferons (IFN-λs) have been demonstrated to inhibit a number of viruses, including HIV. Here, we further examined the anti-HIV effect of IFN-λs in macrophages. We found that IFN-λs synergistically enhanced anti-HIV activity of antiretrovirals [azidothymidine (AZT), efavirenz, indinavir, and enfuvirtide] in infected macrophages. Importantly, IFN-λs could suppress HIV infection of macrophages with the drug-resistant strains, including AZT-resistant virus (A012) and reverse transcriptase inhibitor-resistant virus (TC49). Mechanistically, IFN-λs were able to induce the expression of several important anti-HIV cellular factors, including myxovirus resistance 2 (Mx2), a newly identified HIV post-entry inhibitor and tetherin, a restriction factor that blocks HIV release from infected cells. These observations provide additional evidence to support the potential use of IFN-λs as therapeutics agents for the treatment of HIV infection.

Heroin inhibits HIV-restriction miRNAs and enhances HIV infection of macrophages

Although opioids have been extensively studied for their impact on the immune system, limited information is available about the specific actions of opioids on intracellular antiviral innate immunity against HIV infection. Thus, we investigated whether heroin, one of the most abused drugs, inhibits the expression of intracellular HIV restriction microRNA (miRNA) and facilitates HIV replication in macrophages. Heroin treatment of macrophages enhanced HIV replication, which was associated with the downregulation of several HIV restriction miRNAs. These heroin-mediated actions on the miRNAs and HIV could be antagonized by naltrexone, an opioid receptor antagonist. Furthermore, the in vitro negative impact of heroin on HIV-associated miRNAs was confirmed by the in vivo observation that heroin addicts had significantly lower levels of macrophage-derived HIV restriction miRNAs than those in the control subjects. These in vitro and in vivo findings indicate that heroin use compromises intracellular anti-HIV innate immunity, providing a favorable microenvironment for HIV survival in the target cells.

Comparison of antiviral activity of lambda-interferons against HIV replication in macrophages

Lambda-interferons (IFN-λs) have been demonstrated as having the ability to inhibit HIV replication in macrophages. However, specific differences in signaling transduction and anti-HIV activity in macrophages between different IFN-λs are unclear. Here, we showed that although all 3 members of (IFN-λ1, λ2, and λ3) IFN-λ family induced the expression of a number of genes of janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway in monocyte-derived macrophages, IFN-λ1 or IFN-λ3 induced higher levels of antiviral IFN-stimulated genes (ISGs) expression than did IFN-λ2. In addition, IFN-λ1 or IFN-λ3 induced higher levels of several pattern recognition receptors (PPRs) than did IFN-λ2. Incubation of IFN-λs with HIV-infected macrophages showed that IFN-λ1 or IFN-λ3 is more potent in anti-HIV activity than IFN-λ2. We also showed that IFN-λ treatment before HIV infection was more potent in HIV inhibition than that after HIV infection. Further investigations showed that the inductions of ISGs and PPRs expression by IFN-λs were largely compromised by HIV infection. These findings provide further experimental evidence that IFN-λs have therapeutic potential in treatment of HIV infection.

Are infants unique in their ability to be "functionally cured" of HIV-1?

The recent report of an infant that appears to have achieved a "functional cure" of HIV-1 following receipt of antiretroviral therapy (ART) within 30 hours of birth raises many questions: was the child infected? Was this result due to unique features of this particular infant's immune system, the immune system of infants or the very early initiation of effective ART? In this manuscript, we discuss the pathogenesis of HIV-1 in infants, highlighting the unique features of infant immune development and how these may inform efforts to cure HIV infection. We will also compare the path to infant "cure" to cures in adults.

Immunology of pediatric HIV infection

Most infants born to human immunodeficiency virus (HIV)-infected women escape HIV infection. Infants evade infection despite an immature immune system and, in the case of breastfeeding, prolonged repetitive exposure. If infants become infected, the course of their infection and response to treatment differs dramatically depending upon the timing (in utero, intrapartum, or during breastfeeding) and potentially the route of their infection. Perinatally acquired HIV infection occurs during a critical window of immune development. HIV's perturbation of this dynamic process may account for the striking age-dependent differences in HIV disease progression. HIV infection also profoundly disrupts the maternal immune system upon which infants rely for protection and immune instruction. Therefore, it is not surprising that infants who escape HIV infection still suffer adverse effects. In this review, we highlight the unique aspects of pediatric HIV transmission and pathogenesis with a focus on mechanisms by which HIV infection during immune ontogeny may allow discovery of key elements for protection and control from HIV.

The productive entry pathway of HIV-1 in macrophages is dependent on endocytosis through lipid rafts containing CD4

Macrophages constitute an important reservoir of HIV-1 infection, yet HIV-1 entry into these cells is poorly understood due to the difficulty in genetically manipulating primary macrophages. We developed an effective genetic approach to manipulate the sub-cellular distribution of CD4 in macrophages, and investigated how this affects the HIV-1 entry pathway. Pluripotent Stem Cells (PSC) were transduced with lentiviral vectors designed to manipulate CD4 location and were then differentiated into genetically modified macrophages. HIV-1 infection of these cells was assessed by performing assays that measure critical steps of the HIV-1 lifecycle (fusion, reverse transcription, and expression from HIV-1 integrants). Expression of LCK (which tethers CD4 to the surface of T cells, but is not normally expressed in macrophages) in PSC-macrophages effectively tethered CD4 at the cell surface, reducing its normal endocytic recycling route, and increasing surface CD4 expression 3-fold. This led to a significant increase in HIV-1 fusion and reverse transcription, but productive HIV-1 infection efficiency (as determined by reporter expression from DNA integrants) was unaffected. This implies that surface-tethering of CD4 sequesters HIV-1 into a pathway that is unproductive in macrophages. Secondly, to investigate the importance of lipid rafts (as detergent resistant membranes - DRM) in HIV-1 infection, we generated genetically modified PSC-macrophages that express CD4 mutants known to be excluded from DRM. These macrophages were significantly less able to support HIV-1 fusion, reverse-transcription and integration than engineered controls. Overall, these results support a model in which productive infection by HIV-1 in macrophages occurs via a CD4-raft-dependent endocytic uptake pathway.

Alcohol enhances HIV infection of cord blood monocyte-derived macrophages

Alcohol consumption or alcohol abuse is common among pregnant HIV(+) women and has been identified as a potential behavioral risk factor for the transmission of HIV. In this study, we examined the impact of alcohol on HIV infection of cord blood monocyte-derived macrophages (CBMDM). We demonstrated that alcohol treatment of CBMDM significantly enhanced HIV infection of CBMDM. Investigation of the mechanisms of alcohol action on HIV demonstrated that alcohol inhibited the expression of several HIV restriction factors, including anti-HIV microRNAs, APOBEC3G and APOBEC3H. Additionally, alcohol also suppressed the expression of IFN regulatory factor 7 (IRF-7) and retinoic acid-inducible gene I (RIG-I), an intracellular sensor of viral infection. The suppression of these IFN regulatory factors was associated with reduced expression of type I IFN. These experimental findings suggest that maternal alcohol consumption may facilitate HIV infection, promoting vertical transmission of HIV.

Methamphetamine inhibits Toll-like receptor 9-mediated anti-HIV activity in macrophages

Toll-like receptor 9 (TLR9) is one of the key sensors that recognize viral infection/replication in the host cells. Studies have demonstrated that methamphetamine (METH) dysregulated host cell innate immunity and facilitated HIV infection of macrophages. In this study, we present new evidence that METH suppressed TLR9-mediated anti-HIV activity in macrophages. Activation of TLR9 by its agonist CpG-ODN 2216 inhibits HIV replication, which was demonstrated by increased expression of TLR9, interferon (IFN)-α, IFN regulatory factor-7 (IRF-7), myeloid differentiation factor 88 (MyD88), and myxovirus resistance gene A (MxA) in macrophages. However, METH treatment of macrophages greatly compromised the TLR9 signaling-mediated anti-HIV effect and inhibited the expression of TLR9 downstream signaling factors. Dopamine D1 receptor (D1R) antagonists (SCH23390) could block METH-mediated inhibition of anti-HIV activity of TLR9 signaling. Investigation of the underlying mechanisms of the METH action showed that METH treatment selectively down-regulated the expression of TLR9 on macrophages, whereas it had little effect on the expression of other TLRs. Collectively, our results provide further evidence that METH suppresses host cell innate immunity against HIV infection by down-regulating TLR9 expression and its signaling-mediated antiviral effect in macrophages.

RIG-I activation inhibits HIV replication in macrophages

The RIG-I signaling pathway is critical in the activation of the type I IFN-dependent antiviral innate-immune response. We thus examined whether RIG-I activation can inhibit HIV replication in macrophages. We showed that the stimulation of monocyte-derived macrophages with 5'ppp-dsRNA, a synthetic ligand for RIG-I, induced the expression of RIG-I, IFN-α/β, and several IRFs, key regulators of the IFN signaling pathway. In addition, RIG-I activation induced the expression of multiple intracellular HIV-restriction factors, including ISGs, several members of the APOBEC3 family, tetherin and CC chemokines, the ligands for HIV entry coreceptor (CCR5). The inductions of these factors were associated with the inhibition of HIV replication in macrophages stimulated by 5'ppp-dsRNA. These observations highlight the importance of RIG-I signaling in macrophage innate immunity against HIV, which can be beneficial for the treatment of HIV disease, where intracellular immune defense is compromised by the virus.

Modulation of intracellular restriction factors contributes to methamphetamine-mediated enhancement of acquired immune deficiency syndrome virus infection of macrophages

Epidemiological studies have demonstrated that the use of methamphetamine (METH), a sympathomimetic stimulant, is particularly common among patients infected with HIV. In vitro studies have determined that METH enhances HIV infection of CD4+ T cells, monocyte-derived dendritic cells, and macrophages. In addition, animal studies have also showed that METH treatment increases brain viral load of SIV-infected monkeys and promotes HIV replication and viremia in HIV/hu-CycT1 transgenic mice. However, the mechanisms (s) of METH actions on HIV remain to be determined. In this study, we investigated the impact of METH on intracellular restriction factors against HIV and SIV. We demonstrated that METH treatment of human blood mononuclear phagocytes significantly affected the expression of anti-HIV microRNAs and several key elements (RIG-I, IRF-3/5, SOCS-2, 3 and PIAS-1, 3, X, Y) in the type I IFN pathway. The suppression of these innate restriction factors was associated with a reduced production of type I IFNs and the enhancement of HIV or SIV infection of macrophages. These findings indicate that METH use impairs intracellular innate antiviral mechanism(s) in macrophages, contributing to cell susceptibility to the acquired immune deficiency syndrome (AIDS) virus infection.

CD56+ T cells inhibit HIV-1 infection of macrophages

CD56+ T cells, the crucial component of the host innate immune system, play an important role in defense against viral infections. We investigated the noncytolytic anti-HIV-1 activity of primary CD56+ T cells. SNs collected from CD56+ T cell cultures inhibited HIV-1 infection and replication. This CD56+ T SN-mediated anti-HIV-1 activity was broad-spectrum, as CD56+ T SNs could inhibit infections by laboratory-adapted and clinical strains of HIV-1. The antibody to IFN-γ could partially block the CD56+ T SN-mediated anti-HIV effect. Investigation of mechanism(s) of the CD56+ T cell action on HIV-1 showed that although CD56+ T SN had little effect on HIV-1 entry coreceptor CCR5 expression, CD56+ T SN induced the expression of CC-chemokines, the ligands for CCR5. The antibodies to CC-chemokines also significantly blocked CD56+ T SN-mediated anti-HIV activity. Furthermore, CD56+ T SN up-regulated the expression of STAT-1/-2 and enhanced the expression of IRF1, -3, -7, and -9, resulting in the induction of endogenous IFN-α/β expression in macrophages. Moreover, CD56+ T SN up-regulated intracellular expression of APOBEC3G/3F, the recently identified HIV-1 restriction factors. These findings provide compelling evidence that CD56+ T cells may have a critical role in innate immunity against HIV-1 infection.

IFN-λ3 inhibits HIV infection of macrophages through the JAK-STAT pathway

BACKGROUND

Interferon lambda 3 (IFN-λ3) is a newly identified cytokine with antiviral activity, and its single nucleotide polymorphisms are strongly associated with the treatment effectiveness and development of chronic hepatitis C virus infection. We thus examined the potential of IFN-λ3 to inhibit HIV replication and the possible mechanisms of the anti-HIV action by IFN-λ3 in human macrophages.

PRINCIPAL FINDINGS

Under different conditions (before, during, and after HIV infection), IFN-λ3 significantly inhibited viral replication in macrophages, which was associated with the induction of multiple antiviral cellular factors (ISG56, MxA, OAS-1, A3G/F and tetherin) and IFN regulatory factors (IRF-1, 3, 5, 7 and 9). This anti-HIV action of IFN-λ3 could be compromised by the JAK-STAT inhibitor. In addition, IFN-λ3 treatment of macrophages induced the expression of toll-like receptor 3 (TLR3) and two key adaptors (MyD88 and TRIF) in type I IFN pathway activation. However, HIV infection compromised IFN-λ3-mediated induction of the key elements in JAK-STAT signaling pathway.

CONCLUSIONS

These data indicate that IFN-λ3 exerts its anti-HIV function by activating JAK-STAT pathway-mediated innate immunity in macrophages. Future in vivo studies are necessary in order to explore the potential for developing IFN-λ3-based therapy for HIV disease.

Morphine suppresses IFN signaling pathway and enhances AIDS virus infection

BACKGROUND

Opioids exert a profound influence on immunomodulation and enhance HIV infection and replication. However, the mechanism(s) of their action remains to be determined. We thus investigated the impact of morphine on the intracellular innate antiviral immunity.

METHODOLOGY/PRINCIPAL FINDINGS

Seven-day-cultured macrophages were infected with equal amounts of cell-free HIV Bal or SIV Delta(B670) for 2 h at 37°C after 24 h of treatment with or without morphine. Effect of morphine on HIV/SIV infection and replication was evaluated by HIV/SIV RT activity assay and indirect immunofluorescence for HIV p24 or SIV p28 antigen. The mRNA expression of cellular factors suppressed or induced by morphine treatment was analyzed by the real-time RT-PCR. We demonstrated that morphine treatment of human blood monocyte-derived macrophages significantly inhibited the expression of interferons (IFN-α, IFN-β and IFN-λ) and IFN-inducible genes (APOBEC3C/3F/3G and 3H). The further experiments showed that morphine suppressed the expression of several key elements (RIG-I and IRF-7) in IFN signaling pathway. In addition, morphine treatment induced the expression of suppressor of cytokine signaling protein-1, 2, 3 (SOCS-1, 2, 3) and protein inhibitors of activated STAT-1, 3, X, Y (PIAS-1, 3, X, Y), the key negative regulators of IFN signaling pathway.

CONCLUSIONS

These findings indicate that morphine impairs intracellular innate antiviral mechanism(s) in macrophages, contributing to cell susceptibility to AIDS virus infection.

Tetherin has negligible activity in restricting hepatitis C virus in hepatocytes

We investigated the ability of tetherin, a recently identified antiviral factor, in restricting hepatitis C virus (HCV) in the Japanese fulminant hepatitis-1 (JFH-1) infectious cell culture system. Human hepatocytes (Huh7, Huh7.5.1) expressedlow levels of endogenous tetherin, which could be induced by IFN-α. However, tetherin contributes little to IFN-α-mediated anti-HCV JFH-1 activity. Although tetherin could inhibit Vpu-deleted HIV-1 release, it had negligible activity in restricting HCV JFH-1 release from hepatocytes, which was evidenced by unaffected levels of intracellular/extracellular HCV RNA and infectious virus. The failure of tetherin's anti-HCV activity could not be related to the counteraction of HCV, as HCV infection of hepatocytes affected neither tetherin expression nor anti-HIV function of tetherin. These observations imply that tetherin has negligible activity in the restriction of HCV JFH-1 in human hepatocytes.

NMDA receptor modulation by the neuropeptide apelin: implications for excitotoxic injury

Excitotoxic neuronal damage via over-activation of the NMDA receptor has been implicated in many neurodegenerative diseases. In vitro modeling of excitotoxic injury has shown that activation of G-protein coupled receptors (GPCRs) counteracts such injury through modulation of neuronal pro-survival pathways and/or NMDA receptor signaling. We have previously demonstrated that the GPCR APJ and its endogenous neuropeptide ligand apelin can protect neurons against excitotoxicity, but the mechanism(s) of this neuroprotection remain incompletely understood. We hypothesized that apelin can promote neuronal survival by activating pro-survival signaling as well as inhibiting NMDA receptor-mediated excitotoxic signaling cascades. Our results demonstrate that (i) apelin activates pro-survival signaling via inositol trisphosphate (IP(3) ), protein kinase C (PKC), mitogen-activated protein kinase kinase 1/2 (MEK1/2), and extracellular signal-regulated kinase-1/2 (ERK1/2) to protect against excitotoxicity, and (ii) apelin inhibits excitotoxic signaling by attenuating NMDA receptor and calpain activity, and by modulating NMDA receptor subunit NR2B phosphorylation at serine 1480. These studies delineate a novel apelinergic signaling pathway that concurrently promotes survival and limits NMDA receptor-mediated injury to protect neurons against excitotoxicity. Defining apelin-mediated neuroprotection advances our understanding of neuroprotective pathways and will potentially improve our ability to develop therapeutics for excitotoxicity-associated neurodegenerative disorders.

HIV-1 co-receptor usage: influence on mother-to-child transmission and pediatric infection

Viral CCR5 usage is not a predictive marker of mother to child transmission (MTCT) of HIV-1. CXCR4-using viral variants are little represented in pregnant women, have an increased although not significant risk of transmission and can be eventually also detected in the neonates. Genetic polymorphisms are more frequently of relevance in the child than in the mother. However, specific tissues as the placenta or the intestine, which are involved in the prevalent routes of infection in MTCT, may play an important role of selective barriers. The virus phenotype of the infected children, like that of adults, can evolve from R5 to CXCR4-using phenotype or remain R5 despite clinical progression to overt immune deficiency. The refined classification of R5 viruses into R5(narrow) and R5(broad) resolves the enigma of the R5 phenotype being associated with the state of immune deficiency. Studies are needed to address more in specific the relevance of these factors in HIV-1 MTCT and pediatric infection of non-B subtypes.

Associations between use of crack cocaine and HIV-1 disease progression: research findings and implications for mother-to-infant transmission

Recent in vitro and in vivo research has suggested that cocaine has a direct effect on the pathogenesis of AIDS. These findings are confirmed by epidemiological studies linking the use of injected, inhaled, and smoked (crack) cocaine and indicators of HIV disease progression, even among adherent users of highly active antiretroviral therapy. Recent studies of vertical HIV transmission suggest that cocaine use may play a role in mother-to-child infection via alteration of maternal immune responses, enhanced viral replication in maternal immune cells, or alterations in the immune systems of neonates or infants. The purpose of this article is to review research conducted over the past several decades on associations between use of cocaine and HIV disease progression, especially among HIV+ women, and to explore its potential relevance for understanding mother-to-infant transmission of HIV.

Drugs of abuse and HIV infection/replication: implications for mother-fetus transmission

Human immunodeficiency virus (HIV) infection and progression of acquired immunodeficiency syndrome (AIDS) can be modulated by a number of cofactors, including drugs of abuse. Opioids, cocaine, cannabinoids, methamphetamine (METH), alcohol, and other substances of abuse have been implicated as risk factors for HIV infection, as they all have the potential to compromise host immunity and facilitate viral replication. Although epidemiologic evidence regarding the impact of drugs of abuse on HIV disease progression is mixed, in vitro studies as well as studies using in vivo animal models have indicated that drugs of abuse have the ability to enhance HIV infection/replication. Drugs of abuse may also be a risk factor for perinatal transmission of HIV. Because high levels of viral load in maternal blood are associated with increased risk of HIV vertical transmission, it is likely that drugs of abuse play an important role in promoting mother-fetus transmission. Furthermore, because the neonatal immune system differs qualitatively from the adult system, it is possible that maternal exposure to drugs of abuse would exacerbate neonatal immunity defects, facilitating HIV infection of neonate immune cells and promoting HIV vertical transmission. The availability and use of antiretroviral therapy for women infected with HIV increase, there is an increasing interest in determining the impact of drug abuse on efficacy of AIDS Clinical Trials Group (ACTG)-standardized treatment regimens for woman infected with HIV in the context of HIV vertical transmission.

Lambda interferon inhibits human immunodeficiency virus type 1 infection of macrophages

The newly identified type III interferon (IFN-lambda) has antiviral activity against a broad spectrum of viruses. We thus examined whether IFN-lambda has the ability to inhibit human immunodeficiency virus type 1 (HIV-1) infection of blood monocyte-derived macrophages that expressed IFN-lambda receptors. Both IFN-lambda1 and IFN-lambda2, when added to macrophage cultures, inhibited HIV-1 infection and replication. This IFN-lambda-mediated anti-HIV-1 activity is broad, as IFN-lambda could inhibit infection by both laboratory-adapted and clinical strains of HIV-1. Investigations of the mechanism(s) responsible for the IFN-lambda action showed that although IFN-lambda had little effect on HIV-1 entry coreceptor CCR5 expression, IFN-lambda induced the expression of CC chemokines, the ligands for CCR5. In addition, IFN-lambda upregulated intracellular expression of type I IFNs and APOBEC3G/3F, the newly identified anti-HIV-1 cellular factors. These data provide direct and compelling evidence that IFN-lambda, through both extracellular and intracellular antiviral mechanisms, inhibits HIV-1 replication in macrophages. These findings indicate that IFN-lambda may have therapeutic value in the treatment of HIV-1 infection.

Methamphetamine enhances HIV infection of macrophages

Epidemiological studies have demonstrated that the use of methamphetamine (meth), a sympathomimetic stimulant, is particularly common among patients infected with HIV. However, there is a lack of direct evidence that meth promotes HIV infection of target cells. This study examined whether meth is able to enhance HIV infection of macrophages, the primary target site for the virus. Meth treatment resulted in a significant and dose-dependent increase of HIV reverse transcriptase activity in human blood monocyte-derived macrophages. Dopamine D1 receptor antagonists (SCH23390 and SKF83566) blocked this meth-mediated increase in the HIV infectivity of macrophages. Investigation of the underlying mechanisms of meth action showed that meth up-regulated the expression of the HIV entry co-receptor CCR5 on macrophages. Additionally, meth inhibited the expression of endogenous interferon-alpha and signal transducer and activator of transcription-1 in macrophages. These findings provide direct in vitro evidence to support the possibility that meth may function as a cofactor in the immunopathogenesis of HIV infection and may lead to the future development of innate immunity-based intervention for meth users with HIV infection.

Natural killer cell inhibits human immunodeficiency virus replication in chronically infected immune cells

Natural killer (NK) cells are a crucial component of the host innate immune system. We investigated the noncytolytic anti-human immunodeficiency virus (HIV) activity of NK cells in chronically HIV-infected immune cells. Supernatants collected from NK cell cultures (both primary NK cells and NK cell lines, YTS and NK 92) inhibited HIV activation in peripheral blood mononuclear cells (PBMCs) from HIV-infected subjects. NK supernatants (NK SN) also suppressed tumor necrosis factor (TNF)-alpha-induced HIV activation in chronically infected cell lines (U1 and ACH-2 cells). The antibody to interferon (IFN)-gamma blocked NK SN-mediated anti-HIV effect, while the antibodies to CC-chemokines had no impact on NK SN-mediated HIV inhibition in U1 and ACH-2 cells. Investigation of mechanism(s) responsible for the NK action showed that NK SN inhibited TNF-alpha-mediated activation of HIV-long-terminal repeat (LTR), and upregulated the expression of signal transducer and activator of transcription (STAT)-1 and phosphorylated P38 mitogen-activated protein kinase (MAPK). The P38 MAPK inhibitor (SB 203580) blocked NK SN-mediated HIV inhibition. These data provide compelling evidence that NK cells have a critical role in controlling HIV activation in the reservoirs.

Differential HIV-1 replication in neonatal and adult blood mononuclear cells is influenced at the level of HIV-1 gene expression

The majority of HIV-1-infected neonates and infants have a higher level of viremia and develop AIDS more rapidly than infected adults, including differences seen in clinical manifestations. To determine the mechanisms of HIV-1 infection in neonates vs. adults, we compared the replication kinetics of HIV-1 in neonatal (cord) and adult blood T lymphocytes and monocyte-derived macrophages (MDM) from seven different donors. We found that HIV-1 replicated 3-fold better in cord blood T lymphocytes compared with adult blood T lymphocytes and 9-fold better in cord MDM than adult MDM. We also show that this differential HIV-1 replication did not depend on differences in cell proliferative capabilities, cell surface expression of CD4, CXCR4, and CCR5, or in the amount of PCR products of reverse transcription, DNA synthesis, and translocation of preintegration complex into the nucleus in cord and adult T lymphocytes and MDM. Furthermore, using a single-cycle replication competent HIV-1-NL4-3-Env(-) luciferase amphotropic virus, which measures HIV-1 transcriptional activity independent of receptor and coreceptor expression, we found there was a 3-fold increase of HIV-1 LTR-driven luciferase expression in cord T lymphocytes compared with adult T lymphocytes and 10-fold in cord MDM than in adult MDM. The HIV-1 LTR-driven luciferase expression correlated with HIV-1 LTR transcription, as measured by ribonuclease protection assay. These data suggest that the increased replication of HIV-1 in cord blood compared with adult blood mononuclear cells is regulated at the level of HIV-1 gene expression, resulting in a higher level of viremia and faster disease progression in neonates than adults.

Morphine inhibits CD8+ T cell-mediated, noncytolytic, anti-HIV activity in latently infected immune cells

Opiates have profound effects on the function of human immune cells and are a possible cofactor in the immunopathogenesis of human immunodeficiency virus (HIV) disease. We investigated the impact of morphine on CD8+ T cell-mediated, noncytotoxic, anti-HIV activity in latently infected human immune cells. Morphine inhibited the noncytotoxic, anti-HIV activity of CD8+ T cells in HIV latently infected cells (U1 and J1.1). Naltrexone abrogated the morphine-mediated, inhibitory effect on the noncytotoxic, anti-HIV activity of CD8+ T cells. Interferon-gamma (IFN-gamma), a potent antiviral cytokine produced by CD8+ T cells, was partially responsible for CD8+ T cell-mediated, noncytotoxic, anti-HIV activity. The anti-HIV activity of IFN-gamma was also compromised by morphine treatment. Further, morphine attenuated CD8+ T cell-mediated suppression of the HIV long-terminal repeat promoter activation. Morphine also inhibited CD8+ T cell-induced expression of the signal transducer and activator of transcription-1, an important transcriptional factor in the IFN signaling pathway. These data provide additional evidence to support the notion that opioids play a role in impairing the anti-HIV function of the immune system.

Down-regulation of CXCR-4 and CCR-5 expression by interferon-gamma is associated with inhibition of chemotaxis and human immunodeficiency virus (HIV) replication but not HIV entry into human monocytes

Alterations in the expression of CXCR4 and CCR5, the co-receptors for HIV entry, may be associated with susceptibility of monocytic cells to HIV infection. Interferon (IFN)-gamma has been shown to inhibit HIV replication in monocytic cells, but the molecular mechanism involved is not well understood. To determine if IFN-gamma regulates HIV replication by altering CXCR-4/CCR-5 expression and hence virus entry into monocytic cells, we investigated the effects of IFN-gamma on CXCR-4 and CCR-5 expression and its biological implications with respect to HIV entry, replication and chemotaxis towards the CXCR-4 and CCR-5 ligands SDF-1 and MIP-1alpha, respectively. IFN-gamma decreased CXCR-4 and CCR-5 expression on monocytes derived from HIV-negative adults, HIV-positive adults and HIV-negative cord blood. This down-regulation of chemokine receptor expression did not result in a corresponding change in mRNA expression but was associated with elevated levels of the endogenously produced chemokines SDF-1 and RANTES. Furthermore, IFN-gamma inhibited chemotaxis in response to SDF-1 and MIP-1alpha, inhibited HIV replication, but failed to inhibit virus entry in monocytic cells. These results suggest that although IFN-gamma-induced down-regulation of CXCR-4 and CCR-5 expression is associated with an inhibition of SDF-1-/MIP-1alpha-mediated chemotaxis, IFN-gamma-induced inhibition of HIV replication may be mediated at levels subsequent to the virus entry.

Age-related changes in expression of CXCR4 and CCR5 on peripheral blood leukocytes from uninfected infants born to human immunodeficiency virus type 1-infected mothers

Cross-sectional analysis of human immunodeficiency virus-exposed, uninfected infants revealed high proportions of CXCR4-expressing cells in their cord blood, which declined at 4.5 months and increased between 9 and 15 months to levels approaching those of uninfected adults. Proportions of CCR5-expressing cells, however, were very low in cord blood and subsequently increased with age.

Morphine enhances HIV infection of neonatal macrophages

Perinatal transmission of HIV accounts for almost all new HIV infections in children. There is an increased risk of perinatal transmission of HIV with maternal illicit substance abuse. Little is known about neonatal immune system alteration and subsequent susceptibility to HIV infection after morphine exposure. We investigated the effects of morphine on HIV infection of neonatal monocyte-derived macrophages (MDM). Morphine significantly enhanced HIV infection of neonatal MDM. Morphine-induced HIV replication in neonatal MDM was completely suppressed by naltrexone, the opioid receptor antagonist. Morphine significantly up-regulated CCR5 receptor expression and inhibited the endogenous production of macrophage inflammatory protein-1beta in neonatal MDM. Thus, morphine, most likely through alteration of beta-chemokines and CCR5 receptor expression, enhances the susceptibility of neonatal MDM to HIV infection, and may have a cofactor role in perinatal HIV transmission and infection.

CCR5 expression and beta-chemokine production during placental neonatal monocyte differentiation

The stage of maturation of monocytes affects their susceptibility to HIV infection. The beta-chemokines and their receptor CCR5 play a crucial role in inflammatory reactions and HIV infection. We therefore examined the correlation between the expression of CCR5 and beta-chemokine production and the susceptibility to HIV infection during cord monocyte (CM) differentiation into macrophages. CM and CM-derived macrophages (CMDM) were examined for beta-chemokine and CCR5 expression. The susceptibility of the CM cultured in vitro at different time points to HIV infection was also determined. Although the levels of CCR5 mRNA expression in freshly isolated CM are comparable to those in CMDM, CM had significantly lower levels of CCR5 protein on the cell surface than CMDM did. Steady increase of CCR5 protein expression on the cell surface was observed during CM differentiation into macrophages. The CCR5 expression correlated with the increased susceptibility to HIV infection by CMDM. Although there was no significant difference in endogenous beta-chemokine production between CM and CMDM, HIV infection of CMDM significantly enhanced production of macrophage inflammatory protein-1alpha and -1beta. CCR5 receptor plays a critical role in HIV infection of neonatal blood monocyte/macrophages.

The macrophage response to HIV-1: Intracellular control of X4 virus replication accompanied by activation of chemokine and cytokine synthesis

During human immunodeficiency virus (HIV)-1 infection, T lymphocytes and macrophages play dual roles. They are the primary targets for virus replication, but they are also primary effector cells in acquired and innate immunity, respectively. The authors are now investigating how these roles come together in the response of human monocyte-derived macrophages (MDM) to certain HIV-1. The authors and others have previously shown that MDM permit entry of some X4 virus strains, but control viral replication intracellularly. In the present study, viral DNA synthesis, entry into the nucleus, and transcription to RNA were all observed in X4 virus-infected MDM. MDM arrested HIV-1 replication prior to expression of mature capsid antigen p24 and production of cell-free infectious viral particles. Cell-associated transmissible HIV-1 was detected by cocultivation of infected MDM and susceptible T lymphocytes. A second protective response of MDM to specific R5 as well as X4 HIV-1 was identified in rapid and extensive secretion of tumor necrosis factor-alpha, macrophage inflammatory protein-1alpha, and RANTES. These findings support the view that MDM act aggressively to control HIV-1 replication: X4 strains by severely limiting the progeny virus production and R5 strains by producing beta-chemokines competent to block virus entry into target cells. Optimizing these innate immune responses offers another means to control HIV-1 infection in the human host.

In vitro detection of apoptosis in monocytes/macrophages infected with human coronavirus

Human coronavirus (HCoV) strain 229E infection, but not HCoV strain OC43 infection, of monocytes/macrophages from healthy donors and patients with multiple sclerosis in remission resulted in increased apoptosis, as measured by DNA changes and annexin V staining. Apoptosis correlated with the differential release of infectious virus. HCoV strain 229E titers were 10(3.5) to 10(6) 50% tissue culture-infective doses (TCID(50))/ml, and HCoV strain OC43 titers were only 10(1.2) to 10(2.7) TCID(50)/ml.

C-C chemokine profile of cord blood mononuclear cells: selective defect in RANTES production

Three C-C chemokines inhibit human immunodeficiency virus (HIV) entry into macrophages: macrophage inflammatory protein-1 (MIP-1), MIP-1β, and regulated-upon activation, normal T-cell expressed and secreted (RANTES). We studied the ability of placental cord blood mononuclear cells (CBMC) to secrete these C-C chemokines in comparison to adult blood mononuclear cells (ABMC). CBMC had diminished ability to secrete RANTES, as determined by enzyme-linked immunosorbent assay. Secretion of MIP-1 and MIP-1β were similar in CBMC and ABMC. Whereas MIP-1 and MIP-1β secretion were comparable in monocytes and lymphocytes, RANTES was secreted primarily by lymphocytes. Flow cytometric analysis of RANTES expression showed diminished intracellular RANTES expression in cord blood lymphocytes (CBL) compared to adult (peripheral) blood lymphocytes (ABL). A subset analysis of RANTES-producing CBL and ABL demonstrated that RANTES was produced predominantly by CD8+/CD45RO+ cells. CBL had a reduced proportion of CD8+/CD45RO+ cells compared with ABL, which may account for the diminished RANTES secretion by CBMC. These results may be relevant to the pathogenesis of perinatal HIV infection.

Association between the biological characteristics of HIV-1, vertical transmission of infection and clinical progression of pediatric disease

The design of effective prophylactic measures to prevent the vertical transmission of HIV-1 and of therapies to alter the natural progression of pediatric HIV disease requires a thorough understanding of basic pathogenetic principles. Maternal viral load, the biological behavior of HIV, such as replicative capacity in different types of cells, monocyte/macrophage tropism, and the capacity of the infant's cells to support infection have all been assessed for their contribution to the risk of mother-to-child transmission. Similarly, the effects of viral load and phenotype (e.g. replicative capacity, cell tropism, syncytium-inducing capacity and the use of chemokine co-receptors) have all been investigated as parameters associated with variations in the expression of clinical disease in children. Some of the extant data are conflicting, but general principles regarding pathogenesis are beginning to emerge.

Interferon-γ Upregulates CCR5 Expression in Cord and Adult Blood Mononuclear Phagocytes

The C-C chemokine receptors CCR5 and CCR3 are fusion coreceptors for human immunodeficiency virus (HIV) entry into macrophages. The regulation of their expression influences infectivity by HIV. We report here that interferon-γ (IFN-γ) a cytokine that has bidirectional effects on HIV infection of macrophages, significantly upregulated CCR5 and CCR3 cell surface expression in human mononuclear phagocytes isolated from placental cord blood and adult peripheral blood. Monocytes treated with IFN-γ showed increased chemotaxis to the CCR5 ligands macrophage inflammatory protein-1 (MIP-1) and MIP-1β, confirming the functional relevance of IFN-γ–induced CCR5 expression. However, IFN-γ suppressed HIV entry into macrophages. Interestingly, we demonstrated that IFN-γ inhibited cell surface expression of CD4, the major receptor for HIV. This finding may explain the suppressive effect of IFN-γ on HIV entry into macrophages, despite its enhancing effect on the expression of CCR5 and CCR3 by these cells. In addition, IFN-γ–induced secretion of C-C chemokines (RANTES, MIP-1, and MIP-1β) by mononuclear phagocytes may also suppress HIV entry into macrophages. These data provide further evidence for cytokine-mediated regulation of CCR5 expression and are consistent with a novel paradigm in which cytokines regulate HIV infection and leukocyte migration by reciprocal and opposing effects on the expression of CD4 and chemokine receptors.

Interferon-γ Upregulates CCR5 Expression in Cord and Adult Blood Mononuclear Phagocytes

The C-C chemokine receptors CCR5 and CCR3 are fusion coreceptors for human immunodeficiency virus (HIV) entry into macrophages. The regulation of their expression influences infectivity by HIV. We report here that interferon-γ (IFN-γ) a cytokine that has bidirectional effects on HIV infection of macrophages, significantly upregulated CCR5 and CCR3 cell surface expression in human mononuclear phagocytes isolated from placental cord blood and adult peripheral blood. Monocytes treated with IFN-γ showed increased chemotaxis to the CCR5 ligands macrophage inflammatory protein-1 (MIP-1) and MIP-1β, confirming the functional relevance of IFN-γ–induced CCR5 expression. However, IFN-γ suppressed HIV entry into macrophages. Interestingly, we demonstrated that IFN-γ inhibited cell surface expression of CD4, the major receptor for HIV. This finding may explain the suppressive effect of IFN-γ on HIV entry into macrophages, despite its enhancing effect on the expression of CCR5 and CCR3 by these cells. In addition, IFN-γ–induced secretion of C-C chemokines (RANTES, MIP-1, and MIP-1β) by mononuclear phagocytes may also suppress HIV entry into macrophages. These data provide further evidence for cytokine-mediated regulation of CCR5 expression and are consistent with a novel paradigm in which cytokines regulate HIV infection and leukocyte migration by reciprocal and opposing effects on the expression of CD4 and chemokine receptors.

Substance P C-terminal octapeptide analogues augment tumor necrosis factor-alpha release by human blood monocytes and macrophages

We have investigated the effects of the substance P C-terminal octapeptide analogues [Pro4, Glu (OBzl)11] SP4-11, [Hyp4, Glu(OBzl)11] SP4-11, [cHyp4, Glu(OBzl)11] SP4-11 and [kPro4, Glu(OBzl)11] SP4-11 on the constitutive and/or lipopolysaccharide (LPS)-induced expression of tumor necrosis factor (TNF-alpha) in both freshly isolated human blood monocytes (FIBM) and monocyte-derived macrophages (MDM). The cells were treated with substance P and the substance P analogues at various concentrations (10-14 to 10-6 M) in the presence or absence of LPS and culture supernatants were analyzed for TNF-alpha as measured by an enzyme immunosorbent assay (ELISA). Monocytes and macrophages treated with the substance P analogues alone increased TNF-alpha secretion at a magnitude similar to the effect of entire undecapeptide substance P. The stimulatory effects of the substance P analogues on TNF-alpha secretion are inhibited by substance P antagonists, spantide ([D-Arg-1-D-Trp-7-D-Trp-9-Leu-11]-SP) and CP-96,345 (a nonpeptide antagonist of the substance P receptor), indicating that these effects are specific and substance P receptor-mediated. Treatment of monocytes and macrophages with the substance P analogues in combination with LPS, however, showed no synergistic interaction in upregulation of TNF-alpha. These data indicate that the biological effect of substance P on TNF-alpha production by human monocytes and macrophages depends mainly on the sequence of the C-terminal region of the molecule.

Differential tropism and chemokine receptor expression of human immunodeficiency virus type 1 in neonatal monocytes, monocyte-derived macrophages, and placental macrophages

Laboratory-adapted (LA) macrophage-tropic (M-tropic) human immunodeficiency virus type 1 (HIV-1) isolates (e.g., HIV-1(Ba-L)) and low-passage primary (PR) isolates differed markedly in tropism for syngeneic neonatal monocytes, monocyte-derived macrophages (MDMs), and placental macrophages (PMs). Newly adherent neonatal monocytes and cultured PMs were highly refractory to infection with PR HIV-1 isolates yet were permissive for LA M-tropic isolates. Day 4 MDMs were also permissive for LA M-tropic isolates and additionally, were permissive for over half the PR isolates tested. Qualitative differences in PR HIV-1 infection of monocytes/MDMs could not be correlated with CD4 levels alone, and in all three cell types the block to PR HIV-1 strain replication preceded reverse transcription. Neonatal monocyte susceptibility to PR HIV-1 strains correlated with increasing CCR-5 expression during maturation. CCR-5 could not be detected on newly adherent (day 1) neonatal monocytes, in contrast to adult monocytes (H. Naif et al., J. Virol. 72:830-836, 1998), but was readily detectable after 4 to 7 days of culture. However, moderate CCR-5 mRNA levels were present in day 1 neonatal monocytes and remained constant during monocyte maturation. CCR-5 was not detectable on the surface of PMs, yet the receptor was present within permeabilized cells. Notably, two brain-derived PR HIV-1 isolates from a single patient, differing in their V3 loops, were discordant in their abilities to infect neonatal monocytes/MDMs and PMs, yet both isolates could infect newly adherent adult monocytes. Together these data strongly suggest that LA HIV-1 isolates are able to infect neonatal monocytes at earlier stages of maturation and lower-level expression of CCR-5 than PR isolates. The differences between neonatal and adult monocytes in susceptibility to PR isolates may also be related to the level of CCR-5 expression.

Zidovudine administered to women infected with human immunodeficiency virus type 1 and to their neonates reduces pediatric infection independent of an effect on levels of maternal virus

OBJECTIVE

To determine whether zidovudine, administered to reduce vertical transmission of human immunodeficiency virus type 1 (HIV-1), impacts the level of maternal viral DNA within the lymphocytes of infected pregnant women.

STUDY DESIGN

A prospective, nonrandomized study of 42 HIV-1 infected pregnant women. Nineteen women received zidovudine therapy to reduce HIV-1 perinatal transmission, and 23 were untreated. HIV-1 DNA was determined by polymerase chain reaction amplification of lymphocyte DNA from maternal blood samples obtained at the time of delivery. Treated and untreated, transmitting and nontransmitting groups were compared for clinical, virologic, and immunologic parameters with at test or a Fisher Exact Test, and for copies of HIV-1 DNA per 10(6) CD4+ T cells with a Mann-Whitney rank sum test.

RESULTS

Untreated pregnant women who transmitted HIV-1 to their infants had tower CD4+ T-cell counts and a greater degree of immune complex dissociated p24 antigenemia than did the untreated nontransmitting group (p < 0.01) but did not differ significantly with respect to age, race, or mode of delivery. The level of HIV-1 proviral DNA within lymphocytes was significantly greater in the untreated transmitting group than in the nontransmitting mothers (p = 0.003). Zidovudine treatment resulted in a 78% decrease in maternal transmission (p = 0.017). However, there was not a significant difference in DNA copy numbers in CD4+ T cells in the treated compared with the untreated groups.

CONCLUSION

Zidovudine reduces HIV-1 maternal transmission independent of its effect on the level of the maternal peripheral blood proviral load.

Interaction between timing of perinatal human immunodeficiency virus infection and the design of preventive and therapeutic interventions

In 1994, the hypothesis that transmission of human immunodeficiency virus (HIV) from mother to child could be interrupted became a reality when it was shown that a regimen of zidovudine given to HIV-infected pregnant women and their newborn infants could reduce the risk of perinatal transmission by two-thirds. An understanding of the pathogenesis of transmission is crucial for interpreting these results, for design of future interventions and for understanding the natural history of perinatal HIV infection. This paper will review current information regarding the timing of and risk factors for perinatal HIV transmission, and the relationship between the timing of transmission and design of efforts to interrupt transmission and to slow disease progression in infected infants.

Substance P augments interleukin-10 and tumor necrosis factor-alpha release by human cord blood monocytes and macrophages

We have investigated the effects of SP on the constitutive and/or lipopolysaccharide (LPS)-induced expression of interleukin-10 (IL-10) and tumor necrosis factor (TNF-alpha) in both freshly isolated cord blood monocytes (FICBM) and cord blood monocyte-derived macrophages (CBMDM). The cells were treated with SP at various concentrations (10(-14) to 10(-6) M) in the presence or absence of LPS and culture supernatants were analyzed for IL-10 and TNF-alpha as measured by an enzyme immunosorbent assay (ELISA). FICBM and CBMDM treated with SP alone increased TNF-alpha secretion. The stimulatory effects of SP on TNF-alpha secretion are inhibited by a anti-SP polyclonal antibody and SP antagonists, spantide ([D-Arg-1-D-Trp-7-D-Trp-9-Leu-11]-SP) and CP-96,345 (a nonpeptide antagonist of the SP receptor). Although the treatment with SP alone did not enhance IL-10 secretion by both freshly isolated and cultured cord monocytes, treatment with SP in combination with LPS leads to a synergistic interaction in upregulation of IL-10 secretion. Fragments of SP (SP1-4 and SP5-11) in the presence or absence of LPS show little effects on IL-10 secretion by FICBM. SP reverses the inhibitory effect of IFN-gamma on LPS-induced IL-10 secretion by FICBM. In addition, the two SP antagonists and the anti-SP polyclonal antibody blocked the SP effect on IL-10 secretion by FICBM, indicating that these effects are specific and SP receptor mediated. Thus, SP is likely to play an important role in certain inflammatory conditions in the immune and nervous systems.

Effect of gamma interferon on expression of Fc gamma receptors in monocytes of newborn infants and adults

Fc gamma receptors provide an essential link between cellular and humoral immunity, and little is known about their expression in monocytes of newborn infants. We compared baseline and gamma interferon (IFN-gamma)-induced expression of Fc gamma RI and Fc gamma RII protein and Fc gamma RI mRNA in monocytes from healthy, term infants and adults. Fluorescence-activated cell sorter analysis demonstrated that baseline expression of monocyte Fc gamma RI in newborn infants was not significantly different from that in adults, while Fc gamma RII protein expression in monocytes derived from newborns was significantly higher than that for adults (mean channel fluorescence [MCF] for newborns and adults, 5.53 and 4.50, respectively [P = 0.039]). In vitro treatment with recombinant IFN-gamma increased the expression of Fc gamma RI in monocytes of newborns and adults to the same extent (2.4- and 2.2-fold increase in MCF in newborns and adults, respectively, at 42 h). We developed a semiquantitative fluorescence reverse transcriptase PCR which demonstrated a significant increase in mRNA for Fc gamma RI in monocytes of newborns and adults with in vitro IFN-gamma exposure, indicating that IFN-gamma acts by increasing the transcription or transcript stability of Fc gamma RI mRNA. While there was no significant effect of IFN-gamma treatment on Fc gamma RII expression in monocytes from adults, there was a 20% increase in Fc gamma RII in monocytes from newborns (P = 0.009). Monocytes from healthy, term newborns and adults exhibit comparable baseline and IFN-gamma-induced levels of expression of Fc gamma RI and higher baseline and IFN-gamma-induced levels of expression of Fc gamma RII.

Suppression of HIV replication in human monocyte-derived macrophages induced by granulocyte/macrophage colony-stimulating factor

Susceptibility to HIV infection was examined in macrophages differentiated from human monocytes by macrophage colony-stimulating factor (M-CSF) or granulocyte/macrophage colony-stimulating factor (GM-CSF). The replication of macrophage-tropic human immunodeficiency virus type-1 (HIV-1), which was determined by reverse transcriptase (RT) activity, was significantly suppressed in macrophages induced by GM-CSF (GM-type macrophages) but not in those induced by M-CSF (M-type macrophages). Multinucleated giant cells were formed only in M-type macrophages after HIV infection. However, the expression of CD4 molecules on the surface of both types of macrophages was similar and the proviral DNA was detectable in cell lysates of both macrophages, although the amount of proviral DNA in M-type macrophages was higher than that in GM-type macrophages. Many steps have been defined in HIV infection and replication, such as adsorption of HIV to the cell surface, internalization of the viral core into the cytoplasm, uncoating of viral RNA, reverse transcription and integration of proviral DNA into cellular DNA, transcription and translation of proviral DNA, assembly of viral components, and budding of virus particles. Our findings suggested that the suppression of HIV-1 replication in macrophages induced by GM-CSF is mainly due to a disturbance at certain steps of replication after synthesis of the proviral DNA. Thus, the suppression of HIV replication in GM-type macrophages may provide a model of the latency of HIV infection in vivo.