Human immunodeficiency virus type 1 (HIV-1)-induced GRO-alpha production stimulates HIV-1 replication in macrophages and T lymphocytes

Longitudinal patterns of inflammatory mediators after acute HIV infection correlate to intact and total reservoir

Background

Despite the beneficial effects of antiretroviral therapy (ART) initiation during acute HIV infection (AHI), residual immune activation remains a hallmark of treated HIV infection.

Methods

Plasma concentrations of 40 mediators were measured longitudinally in 39 early treated participants of a Belgian AHI cohort (HIV+) and in 21 HIV-negative controls (HIV-). We investigated the association of the inflammatory profile with clinical presentation, plasma viral load, immunological parameters, and in-depth characterization of the HIV reservoir.

Results

While levels of most soluble mediators normalized with suppressive ART, we demonstrated the persistence of a pro-inflammatory signature in early treated HIV+ participants in comparison to HIV- controls. Examination of these mediators demonstrated a correlation with their levels during AHI, which seemed to be viremia-driven, and suggested involvement of an activated myeloid compartment, IFN-γ-signaling, and inflammasome-related pathways. Interestingly, some of these pro-inflammatory mediators correlated with a larger reservoir size and slower reservoir decay. In contrast, we also identified soluble mediators which were associated with favorable effects on immunovirological outcomes and reservoir, both during and after AHI.

Conclusion

These data highlight how the persistent pro-inflammatory profile observed in early ART treated individuals is shaped during AHI and is intertwined with viral dynamics.

Differential Impact of IL-32 Isoforms on the Functions of Coronary Artery Endothelial Cells: A Potential Link with Arterial Stiffness and Atherosclerosis

Chronic inflammation is associated with higher risk of cardiovascular disease (CVD) in people living with HIV (PLWH). We have previously shown that interleukin-32 (IL-32), a multi-isoform proinflammatory cytokine, is chronically upregulated in PLWH and is linked with CVD. However, the mechanistic role of the different IL-32 isoforms in CVD are yet to be identified. In this study, we aimed to investigate the potential impact of IL-32 isoforms on coronary artery endothelial cells (CAEC), whose dysfunction represents a major factor for atherosclerosis. Our results demonstrated that the predominantly expressed IL-32 isoforms (IL-32β and IL-32γ) have a selective impact on the production of the proinflammatory cytokine IL-6 by CAEC. Furthermore, these two isoforms induced endothelial cell dysfunction by upregulating the expression of the adhesion molecules ICAM-I and VCAM-I and the chemoattractants CCL-2, CXCL-8 and CXCL-1. IL-32-mediated expression of these chemokines was sufficient to drive monocyte transmigration in vitro. Finally, we demonstrate that IL-32 expression in both PLWH and controls correlates with the carotid artery stiffness, measured by the cumulated lateral translation. These results suggest a role for IL-32-mediated endothelial cell dysfunction in dysregulation of the blood vessel wall and that IL-32 may represent a therapeutic target to prevent CVD in PLWH.

T-cell activation and B-cell interaction signatures in rectal tissues are associated with HIV replication in ex-vivo model of infection

OBJECTIVE

The rectal mucosa is a critical site of HIV vulnerability. We sought to identify transcriptomic features of rectal mucosal tissue prior to exposure associated with support or restriction of HIV replication.

DESIGN

Rectal tissue from HIV-negative cis gender men ( n  = 57) underwent concurrent RNAseq transcriptomic analyses (two biopsies/participant) and challenge with HIV in the ex-vivo explant model of infection (three biopsies challenged/participant) as part of a larger cohort study to understand the rectal mucosal immune environment among MSM.

METHODS

P24 was quantified in the explant supernatants over a culture period of 18 days via ELISA. Participant median p24 log area under the curve was correlated with bulk transcriptomic data (Illumina HiSeq3000) to identify associations between gene expression and p24 production. Significant differentially expressed genes (DEGs) were identified via DESeq2 analysis and analyzed with Reactome to identify pathways of interest.

RESULTS

In total, 183 DEG (181 upregulated, two downregulated) were associated with higher p24 accumulation in the ex-vivo challenge model, including T-cell activation, B-cell function, and chemokine DEG. Reactome analysis of the upregulated genes identified 'Adaptive Immune System', 'Cytokine Signaling in Immune System', and 'Innate Immune System' as significantly upregulated pathways.

CONCLUSION

For the first time, we identified rectal tissue transcriptomic signatures associated with increased p24 production utilizing an ex-vivo model. Our findings are highly relevant to HIV transmission and the early establishment of HIV reservoirs in humans, and future studies should examine the identified pathways as targets for new or improved biomedical prevention or treatment interventions.

Understanding the complexities of SARS-CoV2 infection and its immunology: A road to immune-based therapeutics

Emerging infectious diseases always pose a threat to humans along with plant and animal life. SARS-CoV2 is the recently emerged viral infection that originated from Wuhan city of the Republic of China in December 2019. Now, it has become a pandemic. Currently, SARS-CoV2 has infected more than 27.74 million people worldwide, and taken 901,928 human lives. It was named first 'WH 1 Human CoV' and later changed to 2019 novel CoV (2019-nCoV). Scientists have established it as a zoonotic viral disease emerged from Chinese horseshoe bats, which do not develop a severe infection. For example, Rhinolophus Chinese horseshoe bats harboring severe acute respiratory syndrome-related coronavirus (SARSr-CoV) or SARSr-Rh-BatCoV appear healthy and clear the virus within 2-4 months period. The article introduces first the concept of EIDs and some past EIDs, which have affected human life. Next section discusses mysteries regarding SARS-CoV2 origin, its evolution, and human transfer. Third section describes COVID-19 clinical symptoms and factors affecting susceptibility or resistance. The fourth section introduces the SARS-CoV2 entry in the host cell, its replication, and the establishment of productive infection. Section five describes the host's immune response associated with asymptomatic, symptomatic, mild to moderate, and severe COVID-19. The subsequent seventh and eighth sections mention the immune status in COVID-19 convalescent patients and re-emergence of COVID-19 in them. Thereafter, the eighth section describes viral strategies to hijack the host antiviral immune response and generate the "cytokine storm". The ninth section describes about transgenic humane ACE2 (hACE2) receptor expressing mice to study immunity, drugs, and vaccines. The article ends with the development of different immunomodulatory and immunotherapeutics strategies, including vaccines waiting for their approval in humans as prophylaxis or treatment measures.

High Abundance of genus Prevotella in the gut of perinatally HIV-infected children is associated with IP-10 levels despite therapy

Perinatal HIV infection is characterized by faster HIV disease progression and higher initial rate of HIV replication compared to adults. While antiretroviral therapy (ART) has greatly reduced HIV replication to undetectable levels, there is persistent elevated inflammation associated with HIV disease progression. Alteration of gut microbiota is associated with increased inflammation in chronic adult HIV infection. Here, we aim to study the gut microbiome and its role in inflammation in treated and untreated HIV-infected children. Examination of fecal microbiota revealed that perinatally infected children living with HIV had significantly higher levels of genus Prevotella that persisted despite ART. These children also had higher levels of soluble CD14 (sCD14), a marker of microbial translocation, and IP-10 despite therapy. The Prevotella positively correlated with IP-10 levels in both treated and untreated HIV-infected children, while genus Prevotella and species Prevotella copri was inversely associated with CD4 count. Relative abundance of genus Prevotella and species Prevotella copri showed positive correlation with sCD14 in ART-suppressed perinatally HIV-infected children. Our study suggests that gut microbiota may serve as one of the driving forces behind the persistent inflammation in children despite ART. Reshaping of microbiota using probiotics may be recommended as an adjunctive therapy along with ART.

Modulation of cytokine release and gene expression by the immunosuppressive domain of gp41 of HIV-1

The transmembrane envelope protein gp41 of the human immunodeficiency virus HIV-1 plays an important role during infection allowing fusion of the viral and cellular membrane. In addition, there is increasing evidence that gp41 may contribute to the immunodeficiency induced by HIV-1. Recombinant gp41 and a synthetic peptide corresponding to a highly conserved domain in gp41, the immunosuppressive (isu) domain, have been shown to inhibit mitogen-induced activation of human peripheral blood mononuclear cells (PBMCs) and to increase release of IL-6 and IL-10 from these cells. We recently reported that a single mutation in the isu domain of gp41 abrogated the immunosuppressive properties and that HIV-1 sequences containing such abrogating mutations had never been isolated from infected individuals. Here, we studied the influence of the isu peptide on the release of 66 cytokines and the expression of 27,000 genes in PBMCs. Incubation of PBMCs with isu peptide homopolymers increased the expression of 16 cytokines among them IL-6 and IL-10, and decreased that of IL-2 and CXCL9. Interestingly, the extend of cytokine modulation was donor-dependent. Among the genes up-regulated were IL-6, IL-8, IL-10 but also MMP-1, TREM-1 and IL-1beta. Most importantly, genes involved in innate immunity such as FCN1 and SEPP1 were found down-regulated. Many changes in cytokine expression demonstrated in our experiments were also found in HIV-1 infected individuals. These data indicate that the isu domain of gp41 has a broad impact on gene expression and cytokine release and therefore may be involved in HIV-1 induced immunopathogenesis.

Enhanced HIV-1 replication in ex vivo ectocervical tissues from post-menopausal women correlates with increased inflammatory responses

Knowledge about early innate immune responses at the mucosal surfaces of the female genital tract is important in understanding the pathogenesis of heterosexual transmission of human immunodeficiency virus type-1 (HIV-1). As estradiol decreases inflammatory responses, we postulated that an estradiol-deficient state such as post-menopause could enhance expression of inflammatory factors that stimulate HIV-1 replication. We compare HIV-1 integration, transcription, and viral p24 release levels among ectocervical tissues obtained from pre- and post-menopausal donors. We detected enhanced HIV-1 p24 release levels in post- compared with pre-menopausal tissues (P<0.0001), but saw no difference in HIV-1 integration. Overall, 100% of post-menopausal tissues exhibited levels of HIV-1 transcription above background compared with only 60% of pre-menopausal tissues. Increased HIV-1 transcription was associated with enhanced interleukin (IL)-1β, IL-6, monocyte chemotactic protein-1, growth-regulated oncogene-α, and interferon-γ-inducible protein-10 expression. Neutralization and nuclear factor-κB-targeting small-interfering RNA experiments both decreased HIV-1 transcription, suggesting that the early inflammatory response may facilitate HIV-1 replication in ex vivo ectocervical tissues from post-menopausal women.

Early viral replication in lymph nodes provides HIV with a means by which to escape NK-cell-mediated control

Acute HIV infection is marked by dramatic viral replication associated with preferential replication within secondary lymphoid tissues, such as lymph nodes (LNs), that is rapidly but incompletely contained to a viral setpoint. Accumulating evidence supports a role for natural killer (NK) cells in the early control of HIV infection; however, little is known about the location of their antiviral control. Given that HIV replicates profusely in LNs during early infection, we sought to define whether changes occurred in the NK cell infiltrate within these sites during the first year of HIV infection. Surprisingly, NK cell numbers and distribution were unaltered during early HIV infection. LN NK cells expressed decreased inhibitory receptors, were more highly activated, and expressed elevated TRAIL, potentially conferring a superior capacity for NK cells to become activated and control infection. Most noticeably, KIR(+) NK cells were rarely detected in the LN during HIV infection, associated with diminished migratory capacity in the setting of reduced expression of CX3CR1 and CXCR1. Thus, incomplete control of HIV viral replication during early disease may be due to the inefficient recruitment of KIR(+) NK cells to this vulnerable site, providing HIV a niche where it can replicate unabated by early NK-cell-mediated innate pressure.

Electrochemiluminescence in bioanalysis

The discovery of electrochemiluminescence (ECL) and its development as a means of detection is truly a success story. Although studies describing ECL were published in the early 1960s, most studies using ECL as a means of detection were not widely published until the mid 1990s. Incorporating ECL into assays provides increased sensitivity, several logs of dynamic range and the ability to electronically control the reaction. These characteristics provide advantages over assays that rely on radioisotopic labels, fluorescence and enzymatic activity. There have been many areas of science that have benefited from the use of ECL, including environmental microbiology, virology, neurobiology, molecular biology and immunology. ECL has improved the understanding and treatment of infectious diseases, cancer, neurodegenerative diseases and even sleep apnea disorders. Drug development has also benefited from ECL via improved assessment of pharmacodynamics, pharmacokinetics and determining immune responses against protein-based therapeutics. This review provides an overview of ECL chemistry and principles with a more detailed emphasis on the applications of ECL-based assays in different areas of science and medicine. The primary purpose of this review is to provide an in-depth discussion of the impact that ECL-based analysis has had on microbiology, immunology, virology, neurodegenerative diseases, molecular biology and drug development. Examples of ECL-based bioanalysis in each of these fields are discussed in conjunction with an overview of ECL principles and instrumentation.

Platelet factor 4 (CXCL4) facilitates human macrophage infection with HIV-1 and potentiates virus replication

Platelet factor 4 (CXCL4), a member of the CXC chemokine subfamily released in high amounts by activated platelets, has been identified as a monocyte survival factor that induces monocyte differentiation into macrophages. Although CXCL4 has been shown to have biological effects unique to chemokines, nothing is known about the role of CXCL4-derived human macrophages or CXCL4 in human immunodeficiency virus (HIV) disease. In this study, CXCL4-derived macrophages are compared with macrophage-colony stimulating factor (M-CSF)-derived macrophages for their ability to support HIV-1 replication. We show that CXCL4-derived macrophages can be infected with macrophage-tropic HIV-1 that uses either CC-chemokine receptor 5 (CCR5) or CXC-chemokine receptor 4 (CXCR4) as a co-receptor for viral entry. We also find that M-CSF and the chemokines, monocyte chemoattractant protein 1 (MCP-1; CCL2) and macrophage-inflammatory-protein-1-alpha (MIP-1alpha; CCL3) are produced upon R5- and X4-tropic HIV-1 replication in both M-CSF- and CXCL4-derived human macrophages. In addition, CXCL4 added to M-CSF-derived macrophages after virus adsorption and maintained throughout the infection enhances HIV-1 replication. We thus propose a novel role for CXCL4 in HIV disease.

Measurement of soluble inflammatory mediators in cerebrospinal fluid of human immunodeficiency virus-positive patients at distinct stages of infection by solid-phase protein array

The objective of this study was to evaluate immune cytokine expression in cerebrospinal fluid (CSF) of patients with human immunodeficiency virus-1 (HIV-1)-associated dementia (HAD) using a novel cytokine array assay. HIV-1 induces a condition resembling classical subcortical dementia, known as HAD. The immune mechanisms contributing to HAD have not been elucidated. Cytokine expression in CSF was determined by solid-phase protein array in 33 neurologically asymptomatic HIV-positive male patients and were compared to levels in non-HIV controls and patients with HAD. Neurological examinations and lumbar and venous punctures were conducted in all patients and controls. Interleukin (IL)-1, IL-4, and IL-10, were up-regulated in all treated acquired immunodeficiency syndrome (AIDS) patients independent of neurological status compared to controls. In contrast, interferon gamma (IFN-gamma), IL-1alpha, IL-15, and tumor necrosis factor alpha (TNF-alpha) were highly expressed in patients with HAD compared to undemented HIV-positive patients. These results show that solid-phase protein array can detect immunological changes in patients infected with HIV. Cytokine expression levels differ in different disease stages and in patients on different treatment paradigms. Pending further validation on a larger number of patients, this method may be a useful tool in CSF diagnostics and the longitudinal evaluation of patient with HAD.

Sulfotyrosines of the Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor promote tumorigenesis through autocrine activation

The Kaposi's sarcoma-associated herpesvirus (KSHV) G protein-coupled receptor (vGPCR) is a bona fide signaling molecule that is implicated in KSHV-associated malignancies. Whereas vGPCR activates specific cellular signaling pathways in a chemokine-independent fashion, vGPCR binds a broad spectrum of CC and CXC chemokines, and the roles of chemokines in vGPCR tumorigenesis remain poorly understood. We report here that vGPCR is posttranslationally modified by sulfate groups at tyrosine residues within its N-terminal extracellular domain. A chemokine-binding assay demonstrated that the tyrosine sulfate moieties were critical for vGPCR association with GRO-alpha (an agonist) but not with IP-10 (an inverse agonist). A sulfated peptide corresponding to residues 12 through 33 of vGPCR, but not the unsulfated equivalent, partially inhibited vGPCR association with GRO-alpha. Although the vGPCR variant lacking sulfotyrosines activated downstream signaling pathways, the ability of the unsulfated vGPCR variant to induce tumor growth in nude mice was significantly diminished. Furthermore, the unsulfated vGPCR variant was unable to induce the secretion of proliferative cytokines, some of which serve as vGPCR agonists. This implies that autocrine activation by agonist chemokines is critical for vGPCR tumorigenesis. Indeed, GRO-alpha increased vGPCR-mediated AKT phosphorylation and vGPCR tumorigenesis in a sulfotyrosine-dependent manner. Our findings support the conclusion that autocrine activation triggered by chemokine agonists via sulfotyrosines is necessary for vGPCR tumorigenesis, thereby providing a rationale for future therapeutic design targeting the tumorigenic vGPCR.

Verification of proposed peripheral biomarkers in mononuclear cells of individuals with schizophrenia

Recent studies reported gene expression alterations in peripheral blood cells (PBC) obtained from patients with schizophrenia as compared to healthy controls. These alterations can not only be regarded as potential biomarkers but can also further our understanding of the disease. In light of previous reports, expression levels of the following genes: APOBEC3B, CXCL1, DRD2, GNAO1, Kir2.3, S100A9, and SELENBP1 in PBCs were compared between 30 first-hospitalized patients with schizophrenia and 26 healthy controls using quantitative real-time PCR. A significant elevation (2.6-fold; p<0.05) was confirmed for transcripts from the gene CXCL1 but not from the other genes investigated. Within the patients group, APOBEC3B expression was inversely correlated with duration of neuroleptic treatment. These findings indicate that gene expression in PBC from patients with schizophrenia may not only vary with the methods used for analysis but also with state-related differences in gene expression.

ELR+ CXC chemokine expression in benign and malignant colorectal conditions

BACKGROUND

CXCR2 chemokine ligands CXCL1, CXCL5 and CXCL6 were shown to be involved in chemoattraction, inflammatory responses, tumor growth and angiogenesis. Here, we comparatively analyzed their expression profile in resection specimens from patients with colorectal adenoma (CRA) (n = 30) as well as colorectal carcinoma (CRC) (n = 48) and corresponding colorectal liver metastases (CRLM) (n = 16).

METHODS

Chemokine expression was assessed by microdissection, quantitative real-time PCR (Q-RT-PCR), the enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC).

RESULTS

In contrast to CXCL6, we demonstrated CXCL1 and CXCL5 mRNA and protein expression to be significantly up-regulated in CRC and CRLM tissue specimens in relation to their matched tumor neighbor tissues. Moreover, both chemokine ligands were demonstrated to be significantly higher expressed in CRC tissues than in CRA tissues thus indicating a progressive increase in the transition from the premalignant condition to the development of the malignant status. Although a comparative analysis of the CXCL1/CXCL5 protein expression profiles in CRC patients revealed that the absolute expression level of CXCL1 was significantly higher in comparison to CXCL5, mRNA- and protein overexpression of CXCL5 in CRC and CRLM tissues was much more pronounced (80- and 60- fold in CRC tissues, respectively) in comparison to CXCL1 (5- and 3.5- fold in CRC tissues, respectively).

CONCLUSION

Our results demonstrate a significant association between CXCL1 and CXCL5 expression with CRC and CRLM suggesting for both chemokine ligands a potential role in the progression from CRA to CRC and thus, in the initiation of CRC.

Human cytomegalovirus and human immunodeficiency virus type-1 co-infection in human cervical tissue

Human cytomegalovirus (HCMV) and human immunodeficiency virus type-1 (HIV-1) infect the female genital tract. A human cervical explant model was developed to study single and dual infection by these viruses in the genital compartment. An HCMV strain expressing green fluorescent protein, and two clinical HCMV strains produced peak viral DNA copies at 14 to 21 days post-infection. Peak levels of HIV-1(Ba-L) p24 antigen occurred at 7 days post-infection. HIV-1(Ba-L) appeared to enhance HCMV in co-infected tissues. Singly and dually infected explants produced increased levels of cytokines IL-6, IL-8, and GRO-alpha in culture supernatants. Immunohistochemical and flow cytometric analysis showed HCMV infection of leukocytes with the phenotype CD45+/CD1a+/CD14+/HLA-DR+ but not stromal or endothelial cells. Cells expressing both GFP and HIV-1 p24 antigen were detected in co-infected tissues. The cervical explants provide an ex vivo human model for examining mechanisms of virus-virus interaction and pathogenesis in clinically relevant tissue.

Induction of IP-10 (CXCL10) in astrocytes following Japanese encephalitis

Chemokines and their receptors are important elements for the selective attraction and activation of various subsets of leukocytes. Interferon-gamma inducible protein (IP-10 or CXCL-10) is a potent chemoattractant and has been suggested to enhance the severity of virus infection and neuronal injury. In order to assess functional importance of this chemokine in viral encephalitis, we have exploited an experimental model of Japanese encephalitis. We report for the first time that in Japanese encephalitis, astrocytes are the predominant source of IP-10. A progressive increase in IP-10 induction following viral infection is concomitant with the increase in IFN-gamma a known inducer of IP-10. However, this increase in IFN-gamma level is not sufficient to confer protection as animals eventually succumb to the infection.

GROalpha is highly expressed in adenocarcinoma of the colon and down-regulates fibulin-1

PURPOSE

The growth-related oncogene alpha (GROalpha) is a secreted interleukin-like molecule that interacts with the CXCR2 G-protein-coupled receptor. We found that the mRNA and protein products of GROalpha are more highly expressed in neoplastic than normal colon epithelium, and we studied potential mechanisms by which GROalpha may contribute to tumor initiation or growth.

EXPERIMENTAL DESIGN

Cell lines that constitutively overexpress GROalpha were tested for growth rate, focus formation, and tumor formation in a xenograft model. GROalpha expression was determined by Affymetrix GeneChip (241 microdissected colon samples), real-time PCR (n = 32), and immunohistochemistry. Primary colon cancer samples were also employed to determine copy number changes and loss of heterozygosity related to the GROalpha and fibulin-1 genes.

RESULTS

In cell cultures, GROalpha transfection transformed NIH 3T3 cells, whereas inhibition of GROalpha by inhibitory RNA was associated with apoptosis, decreased growth rate, and marked up-regulation of the matrix protein fibulin-1. Forced expression of GROalpha was associated with decreased expression of fibulin-1. Expression of GROalpha mRNA was higher in primary adenocarcinomas (n = 132), adenomas (n = 32), and metastases (n = 52) than in normal colon epithelium (P < 0.001). These results were confirmed by real-time PCR and by immunohistochemistry. Samples of primary and metastatic colon cancer showed underexpression of fibulin-1 when compared with normal samples. There were no consistent changes in gene copy number of GROalpha or fibulin-1, implying a transcriptional basis for these findings.

CONCLUSION

Elevated expression of GROalpha is frequent in adenocarcinoma of the colon and is associated with down-regulation of the matrix protein fibulin-1 in experimental models and in clinical samples. GROalpha overexpression abrogates contact inhibition in cell culture models, whereas inhibition of GROalpha expression is associated with apoptosis. Importantly, coexpression of fibulin-1 with GROalpha abrogates key aspects of the transformed phenotype, including tumor formation in a murine xenograft model. Targeting GRO proteins may provide new opportunities for treatment of colon cancer.

Host chemokine (C-C motif) ligand-2 (CCL2) is differentially regulated in HIV type 1 (HIV-1)-infected individuals

Several cytokines and chemokines including chemokine (C-C motif) ligand-2 (CCL2) are induced in HIV-1 infection. However, the impact of HIV-1 viremia on CCL2 regulation is largely unknown. We utilized a DNA oligonucleotide microarray covering 110 inflammatory genes. Five genes were induced by at least 2-fold in PBMCs of HIV-1 viremic (>100,000 RNA copies ml(-1)) as compared with aviremic (<50 RNA copies ml(-1)) individuals. These genes were CCL2, CXC chemokine ligand-10, IFN-gamma, GTP-cyclohydrolase-1 and C-C chemokine receptor-1. In addition to microarray data verification by real-time PCR, analysis of independent patient samples revealed a similar expression pattern. CCL2 was the most strongly regulated gene at mRNA level and its serum concentration was significantly elevated in viremic compared with aviremic and HIV-1 seronegative controls, indicating a positive correlation between viremia and CCL2. Flow cytometric studies demonstrated a higher percentage of CCL2-expressing CD14(+) monocytes in viremic compared with aviremic individuals. These results suggest a highly restricted modulation of host inflammatory gene response by HIV. Genes up-regulated in the viremic state, in particular CCL2, presumably serve as potential enhancing factors in HIV-1 replication, represented by high viral load in HIV-1 viremic patients. Inhibition of increased CCL2 production could provide a new therapeutic intervention in HIV-1 infection.

Reovirus Strain-Dependent Inflammatory Cytokine Responses and Replication Patterns in a Human Monocyte Cell Line

Mammalian Orthoreoviruses are important models for studies of viral pathogenesis. In the rat lung, Reovirus strain type 3 Dearing (T3D) induces substantially more inflammation than does strain type 1 Lang (T1L). To better understand mechanisms underlying differences in the host inflammatory response elicited by T1L and T3D, we characterized cytokine expression patterns induced by those strains after infection of THP-1 monocyte cells. THP-1 cells were adsorbed with either viable or ultraviolet- inactivated T1L and T3D and assayed for mRNA and protein production of growth-regulated oncogene-alpha (GRO-alpha), interleukin-8 (IL-8), or tumor necrosis factor-alpha (TNF-alpha). T3D stimulated mRNA and protein production of all three cytokines, whereas T1L stimulated mRNA and protein production of IL-8 and TNF-alpha but not GRO-alpha. In each case, T3D induced greater cytokine mRNA and protein expression than did T1L. Nonviable virus did not stimulate detectable cytokine secretion, suggesting a requirement for viral RNA synthesis in cytokine induction by THP-1 cells. A greater percentage of THP-1 cells was infected with T1L than T3D as assessed by infectious center assay, and T1L achieved higher yields of infectious progeny than did T3D in infected THP-1 cells as determined by plaque assay. These strain-dependent differences in cytokine responses and corresponding replication patterns in monocyte cells parallel findings made in studies of rat models of pneumonia and provide clues about how Reovirus interfaces with the host innate immune response to produce pulmonary disease.

Anti-human immunodeficiency virus type 1 microbicide cellulose acetate 1,2-benzenedicarboxylate in a human in vitro model of vaginal inflammation

The sexual transmission of human immunodeficiency virus type 1 (HIV-1) is facilitated by inflammation and related epithelial barrier perturbation. Microbicides for vaginal applications are currently being developed to reduce the risk of HIV-1 transmission. However, little is known about their interference with epithelial immune function. In recent clinical trials, nonoxynol-9 (N-9), a virucide with a long history of intravaginal use as a contraceptive, failed to protect against HIV-1 possibly due to mucosal inflammatory damage. Cellulose acetate 1,2-benzenedicarboxylate, also named CAP (for "controls AIDS pandemic"), is an anti-HIV-1 microbicide selected from pharmaceutical excipients that are regarded as safe for oral administration but have not been assessed for potential effects on inflammatory factors in the vaginal environment. Here we use a sensitive human cell culture system to evaluate proinflammatory profiles of soluble CAP in reference to N-9 and known epithelial activators such as tumor necrosis factor alpha (TNF-alpha) and bacterial lysates. Within 6 h of exposure, TNF-alpha and N-9 triggered NF-kappaB and AP-1/cFos activation and upregulated interleukins and an array of chemokines by vaginal and polarized cervical epithelial cells. The induced proinflammatory status continued after removal of stimuli and was confirmed by enhanced transepithelial neutrophil migration. While sustaining stability and anti-HIV-1 activity in the epithelial environment, CAP did not increase the production of proinflammatory mediators during or after exposure, nor did it modify the epithelial resistance to leukocyte traffic. CAP attenuated some TNF-alpha-induced responses but did not interfere with epithelial cytokine responsiveness to gonococcal determinants. The described system may be useful for predicting proinflammatory side effects of other microbicide candidates for vaginal application.

The C-X-C chemokine IP-10 stimulates HIV-1 replication

Chemokines play critical roles in HIV-1 infection, serving both to modulate viral replication and to recruit target cells to sites of infection. Interferon-gamma-inducible protein 10 (IP-10/CXCL10) is a C-X-C chemokine that acts specifically upon activated T cells and macrophages and attracts T cells into the cerebrospinal fluid (CSF) in HIV-associated neurological disease. We now demonstrate that IP-10 stimulates HIV-1 replication in monocyte-derived macrophages and peripheral blood lymphocytes. We further demonstrate that neutralization of endogenous IP-10 or blocking the function of its receptor, CXCR3, reduces HIV-1 replication in these same cells. Therefore, blocking the interaction between IP-10 and CXCR3 represents a possible new target for anti-retroviral therapy.

Role of trophic factors on neuroimmunity in neurodegenerative infectious diseases

Viral infection of the central nervous system elicits a myriad of cellular, vascular, and neuroimmune factors that contribute to acute, subacute, and chronic damage to the brain. In response to cellular damage, the host is capable of producing trophic factors that may protect neuronal, glial, and endothelial cell populations. Both neurotrophic and angiotrophic factors can also operate by modulating the neuroimmune response, which plays a central role in the pathogenesis of the neurodegenerative process. In this regard, crosstalk signaling among host cells, components of the neuroimmune response, and virus could influence cell fate by production of trophic factors that protect or rescue neurons vulnerable to viral damage. In this context, the main objective of this review is to provide an overview of evidence in support of the role of trophic factors in regulating the neuroimmune response in chronic viral infections of the central nervous system. Special emphasis is placed on the interaction of the human immunodeficiency virus (HIV) Tat protein with endothelial, astroglial, microglial, and neuronal cells, resulting in altered expression of vascular endothelial growth factor, fibroblast growth factor, interleukin-8, and regulation of calcium flux via CXCR2, which directly influences neuronal cell fitness.

Interleukin-8 and growth-regulated oncogene alpha mediate angiogenesis in Kaposi's sarcoma

The development of the complex neoplasm Kaposi's sarcoma is dependent on infection with the Kaposi's sarcoma-associated herpesvirus (KSHV) and appears to be greatly enhanced by cytokines and human immunodeficiency virus type 1 (HIV-1) Tat. Interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) are chemokines involved in chemoattraction, neovascularization, and stimulation of HIV-1 replication. We have previously demonstrated that production of GRO-alpha is stimulated by exposure of monocyte-derived macrophages (MDM) to HIV-1. Here we show that exposure of MDM to HIV-1, viral Tat, or viral gp120 leads to a substantial increase in IL-8 production. We also demonstrate that IL-8 and GRO-alpha are induced by KSHV infection of endothelial cells and are crucial to the angiogenic phenotype developed by KSHV-infected endothelial cells in cell culture and upon implantation into SCID mice. Thus, the three known etiological factors in Kaposi's sarcoma pathogenesis-KSHV, HIV-1 Tat, and cellular growth factors-might be linked, in part, through induction of IL-8 and GRO-alpha.

HIV envelope induces a cascade of cell signals in non-proliferating target cells that favor virus replication

Certain HIV-encoded proteins modify host-cell gene expression in a manner that facilitates viral replication. These activities may contribute to low-level viral replication in nonproliferating cells. Through the use of oligonucleotide microarrays and high-throughput Western blotting we demonstrate that one of these proteins, gp120, induces the expression of cytokines, chemokines, kinases, and transcription factors associated with antigen-specific T cell activation in the absence of cellular proliferation. Examination of transcriptional changes induced by gp120 in freshly isolated peripheral blood mononuclear cells and monocyte-derived-macrophages reveals a broad and complex transcriptional program conducive to productive infection with HIV. Observations include the induction of nuclear factor of activated T cells, components of the RNA polymerase II complex including TFII D, proteins localized to the plasma membrane, including several syntaxins, and members of the Rho protein family, including Cdc 42. These observations provide evidence that envelope-mediated signaling contributes to the productive infection of HIV in suboptimally activated T cells.

The nonstructural NS5A protein of hepatitis C virus: an expanding, multifunctional role in enhancing hepatitis C virus pathogenesis

The hepatitis C virus (HCV) NS5A gene product is a phosphorylated 56- to 58-kD nonstructural protein that displays a multitude of activities related to enhancement of viral pathogenesis. Although associated with other viral encoded proteins as part of the viral replicase complex positioned on the cytoplasmic side of the endoplasmic reticulum, a role for NS5A in viral replication has not been defined. Post-translational modifications of NS5A include phosphorylation and potential proteolytic processing to smaller molecular weight forms able to translocate to the nucleus. Both the identification of a putative interferon (IFN) sensitivity-determining region within NS5A, as well as the direct interaction with and inhibition of the IFN-induced double-stranded RNA-dependent protein kinase (PKR) by NS5A remain controversial. Truncated versions of NS5A can act as transcriptional activators, while other recently characterized interactions of NS5A with cellular proteins indicate its pleiotropic role in HCV-host interactions. NS5A itself has no direct effect on IFN-alpha signaling or activation, but other abundant interactions with members of the cellular signaling apparatus, transcription activation machinery and cell cycle-regulatory kinases have been described (e.g. growth factor receptor-bound protein 2, p53, p21/waf and cyclins). Many of these interactions block the apoptotic cellular response to persistent HCV infection. More recently, another altogether different mechanism attenuating the IFN-alpha response was reported based on induction of interleukin (IL)-8. IL-8, in model systems, potentiates viral replication and mutes the nonspecific intracellular IFN antiviral response. Evidence supporting a complex multimechanistic role of NS5A in promoting viral persistence, pathogenesis and, indirectly, viral-related hepatocarcinogenesis indicates its key role in HCV pathobiology.

Interleukin-8 stimulates human immunodeficiency virus type 1 replication and is a potential new target for antiretroviral therapy

Production of the C-X-C chemokines interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) in macrophages is stimulated by exposure to human immunodeficiency virus type 1 (HIV-1). We have demonstrated previously that GRO-alpha then stimulates HIV-1 replication in both T lymphocytes and macrophages. Here we demonstrate that IL-8 also stimulates HIV-1 replication in macrophages and T lymphocytes. We further show that increased levels of IL-8 are present in the lymphoid tissue of patients with AIDS. In addition, we demonstrate that compounds which inhibit the actions of IL-8 and GRO-alpha via their receptors, CXCR1 and CXCR2, also inhibit HIV-1 replication in both T lymphocytes and macrophages, indicating potential therapeutic uses for these compounds in HIV-1 infection and AIDS.