Caterina Serra

HIV-1 kills renal tubular epithelial cells in vitro by triggering an apoptotic pathway involving caspase activation and Fas upregulation.

HIV-infected patients suffer several renal syndromes, which can progress rapidly from renal insufficiency to end-stage renal disease. Histologically, HIV-induced nephropathy is characterized by prominent tubulopathy with apoptosis of tubular cells. Clinical and experimental evidence suggests that renal injury may be directly related to virus infection. Although HIV-1 is a polytropic and not solely lymphotropic pathogen, the susceptibility of renal cells to HIV-1 remains to be determined. This paper demonstrates in vitro the permissiveness of proximal tubular epithelial cells (PTEC) to HIV-1 and describes the effects of PTEC infection to explain the pathogenesis of tubular damage in vivo. The results indicate that PTEC express HIV-specific receptor and coreceptors and sustain virus replication. We observed that HIV-1 infection causes the death of tubular cells by triggering an apoptotic pathway involving caspase activation. Fas upregulation but not Fas ligand expression was found in the infected PTEC. However, after HIV-1 infection, tubular cells became susceptible to apoptosis induced through Fas stimulation. Caspase inhibition prevented the death of the infected PTEC in spite of persistent viral replication. These findings may explain the prominent histopathology of HIV-associated nephropathy and demonstrate that the apoptosis of nonlymphoid cells can be directly induced by HIV-1.

Increased replication of T-cell-tropic HIV strains and CXC-chemokine receptor-4 induction in T cells treated with macrophage inflammatory protein (MIP)-1α, MIP-1β and RANTES β-chemokines

Objective and design: To study, in T-lymphoid cells, the effects of macrophage inflammatory protein (MIP)-1α, MIP-1β and RANTES β-chemokines on the replication of T-cell-tropic HIV-1 strains, since it has been reported that β-chemokines interfere with the replication of macrophage-tropic HIV-1 strains, but not T-cell-tropic strains. Methods: Freshly phytohaemagglutinin (PHA)-activated peripheral blood lymphocytes (PBL) and cultured PHA-activated T cells from healthy volunteers, as well as the C8166 T-cell line, were treated overnight with β-chemokines before infection with T-cell-tropic HIV-1 isolates, or human T-lymphotropic virus type IIIB. HIV replication was followed by detecting the production of infectious particles, p24 antigen, and viral sequences. CXC-chemokine receptor (CXCR)-4 expression was followed by detection and quantification of specific transcripts. Results: Pretreatment of T cells with MIP-1α, MIP-1β and RANTES affected T-cell-tropic strains, increased the replication of HIV-1P1 and HIV-1RPdT strains dose-dependently, as well as virus absorption and provirus DNA accumulation. These findings were associated with increased accumulation of CXCR-4 transcripts, and mediated by the protein tyrosine kinase signalling. Moreover, β-chemokines stimulated PBL proliferation. Conclusions: β-Chemokines increase the adsorption and replication of at least some T-cell-tropic HIV-1 strains, and this is related to stimulated expression of the CXCR-4 coreceptor.

Multiple sclerosis–associated retrovirus (MSRV) in Sardinian MS patients

Abstract—Blood and CSF of Sardinian patients with MS and neurologic control subjects were tested for MS-associated retrovirus (MSRV). CSF detection in MS was 50% at clinical onset, increasing with temporal disease progression, and 40% in control subjects. In blood, MSRV was detected in all MS patients, in most patients with inflammatory neurologic diseases, and rarely in healthy blood donors. MSRV may represent a marker of neurologic diseases of inflammatory origin.

Productive HIV-1 infection of normal human mammary epithelial cells.

Objective, and designTo determine the susceptibility of mammary epithelial cells (MEC) to HIV-1 as breastfeeding is an established route of HIV transmission, although the origin of virus in breastmilk is unclear. MethodsPrimary epithelial cell cultures were derived from the mammary glands of healthy donors; immortalized MEC lines were also used. HIV infection was followed by detection of infectious particle production, p24 antigen, and viral sequences. ResultsSeven out of 11 primary MEC cultures, and two out of three MEC lines were productively infected by HIV-1. Virus replication significantly reduced cell proliferation, although cell viability was only slightly affected. Cytopathic changes were not observed. MEC cultures expressed low levels of surface CD4, galactosylceramide, and CD26, but essentially no human leukocyte antigen (HLA)-DR. Infection of HIV-permissive MEC cells was associated with the upregulation of surface HLA-DR, and CD26. In contrast, the expression of CD4, tissue-specific markers, adhesion molecules, and growth-factor receptors was downregulated. To a lesser extent, similar effects were also observed in non-permissive cells. Hormones (triiodothyronine plus β-estradiol, and prolactin) enhanced HIV replication, possibly through the stimulation of cellular DNA synthesis. ConclusionsWe concluded that HIV-1 replication in ductal/alveolar MEC may be, in part, responsible for the presence of HIV-1 in milk; that hormones may stimulate virus replication;, and that infection reduces the growth of epithelial cells. Although in vitro HIV is produced by MEC to a lesser extent than lymphoid cells, MEC-derived HIV might have selective advantages for the infection of mucosal epithelial cells during breastfeeding.

Human Immunodeficiency Virus-1 Tat Induces Hyperproliferation and Dysregulation of Renal Glomerular Epithelial Cells

Human immunodeficiency virus-associated nephropathy (HIVAN) is etiologically related to the viral infection, but the mechanisms of virus-induced renal injury remain undetermined. Peculiar histopathological features of HIVAN are the enhanced proliferation and the loss of differentiation markers of glomerular epithelial cells (podocytes). We found that podocytes were not permissive to HIV-1 replication. In this study we investigated the effects of the HIV-1 regulatory protein Tat on primary cultures and on a continuous line of podocytes. Our results demonstrated that Tat induced hyperproliferation of these cells in a dose-dependent manner. This activity was primarily mediated by the basic domain of the viral protein. Proteoglycans were required for this phenomenon because Tat-induced increase of podocyte growth was significantly impaired by inhibition of proteoglycan synthesis with beta-D-xyloside. In podocyte cultures Tat promoted both the transcription and the release of basic fibroblast growth factor, which contributed to the enhanced cell proliferation. Moreover, Tat deregulated the podocyte phenotype causing down-regulation of maturity markers such as WT-1 and synaptopodin, alteration of cytoarchitecture, and impairment of permselectivity. Together, these results demonstrate that the interaction of extracellular Tat with podocytes can induce alterations that mimic the pathological changes of podocytes detected in HIVAN.

Expression and activation by Epstein Barr virus of human endogenous retroviruses-W in blood cells and astrocytes: inference for multiple sclerosis.

Background Proposed co-factors triggering the pathogenesis of multiple sclerosis (MS) are the Epstein Barr virus (EBV), and the potentially neuropathogenic MSRV (MS-associated retrovirus) and syncytin-1, of the W family of human endogenous retroviruses. Methodology/Principal Findings In search of links, the expression of HERV-W/MSRV/syncytin-1, with/without exposure to EBV or to EBV glycoprotein350 (EBVgp350), was studied on peripheral blood mononuclear cells (PBMC) from healthy volunteers and MS patients, and on astrocytes, by discriminatory env-specific RT-PCR assays, and by flow cytometry. Basal expression of HERV-W/MSRV/syncytin-1 occurs in astrocytes and in monocytes, NK, and B, but not in T cells. This uneven expression is amplified in untreated MS patients, and dramatically reduced during therapy. In astrocytes, EBVgp350 stimulates the expression of HERV-W/MSRV/syncytin-1, with requirement of the NF-κB pathway. In EBVgp350-treated PBMC, MSRVenv and syncytin-1 transcription is activated in B cells and monocytes, but not in T cells, nor in the highly expressing NK cells. The latter cells, but not the T cells, are activated by proinflammatory cytokines. Conclusions/Significance In vitro EBV activates the potentially immunopathogenic and neuropathogenic HERV-W/MSRV/syncytin-1, in cells deriving from blood and brain. In vivo, pathogenic outcomes would depend on abnormal situations, as in late EBV primary infection, that is often symptomatic, or/and in the presence of particular host genetic backgrounds. In the blood, HERV-Wenv activation might induce immunopathogenic phenomena linked to its superantigenic properties. In the brain, toxic mechanisms against oligodendrocytes could be established, inducing inflammation, demyelination and axonal damage. Local stimulation by proinflammatory cytokines and other factors might activate further HERV-Ws, contributing to the neuropathogenity. In MS pathogenesis, a possible model could include EBV as initial trigger of future MS, years later, and HERV-W/MSRV/syncytin-1 as actual contributor to MS pathogenicity, in striking parallelism with disease behaviour.

In vitro modulation of the multiple sclerosis (MS)-associated retrovirus by cytokines: Implications for MS pathogenesis

Multiple sclerosis (MS)-associated retrovirus (MSRV) is a component of the human endogenous retrovirus (HERV)-W family, with gliotoxic and superantigenic properties, related to MS clinical progression, and transactivated by viral agents. The authors studied MSRV modulation by cytokines involved in vivo in MS course, utilizing peripheral blood mononuclear cells from MSRV-positive and MRSV-negative individuals. Cultured cells from MSRV-negative subjects did not produce virus, whereas spontaneous MSRV release was detected in cultures from MSRV-positive donors; virus release was increased by interleukin (IL)-4 and IL-6 and, to a greater extent, by the detrimental cytokines interferonγ and tumor necrosis factor (TNF)α. Interferonβ, used in MS therapy, inhibits MSRV release. A parallel between the effects of these cytokines on MSRV production in vitro and on MS disease in vivo is observed, which deserves further elucidations.

Multiple sclerosis–associated retrovirus and MS prognosis An observational study

Abstract—MS-associated retrovirus (MSRV) in the CSF may have gliotoxic properties and could be associated with a more disabling MS. The authors tested this hypothesis in 15 untreated patients with MS: 6 MSRV− and 9 MSRV+ at the time of CSF withdrawal. After a 3-year mean follow-up, MSRV− patients showed a stable MS course, whereas MSRV+ patients had a progressive course (p = 0.01).

Multiple sclerosis and multiple sclerosis-associated retrovirus in Sardinia.

Abstract. The island of Sardinia has a high and increasing incidence of multiple sclerosis (MS). In a search for environmental factors that may account for this anomalously high incidence, we looked for evidence of multiple sclerosis-associated retrovirus (MSRV) that has previously been found in the plasma and cerebrospinal fluid of MS patients. We studied 25 MS patients and 25 matched healthy controls of ascertained Sardinian lineage. Blood samples were processed for extracellular RNA extraction. RNAs underwent reverse transcription/nested polymerase chain reaction (RT-PCR) with primers specific for MRSV-pol gene. We found a striking correlation between MSRV positivity and MS disease, but the virus was found also only in controls (100% and 12% respectively; Fishers exact test, p<0.00001). It is unclear whether MSRV exerts any pathogenic role in MS. It is possible that this is simply an epiphenomenon, but even then, it may constitute a diagnostic marker.

Novel reliable real-time PCR for differential detection of MSRVenv and syncytin-1 in RNA and DNA from patients with multiple sclerosis

Two components of the HERV-W family of human endogenous retroviruses are activated during multiple sclerosis (MS) and proposed immunopathogenic co-factors: MSRV (MS-associated retrovirus), and ERVWE1 (whose env protein, syncytin-1, reaches the plasma membrane). MSRVenv and syncytin-1 are closely related, and difficult to distinguish each other. The sequences of extracellular MSRVenv and of syncytin-1 available in GenBank were compared with those found in MS patients and controls of the cohort under study. With respect to syncytin-1, MSRVenv sequences have a 12-nucleotide insertion in the trans-membrane moiety. Based on this insertion, discriminatory real-time PCR assays were developed, that can amplify selectively either MSRVenv or syncytin-1. The data of MS patients and controls indicated that MSRV and ERVWE1 are both expressed in the brain of MS patients, while only MSRV is present in the blood; MSRV was released in culture by PBMCs of MSRV-producer individuals. These cells expressed the complete MSRVenv gene in the absence of syncytin-1 expression, up to the final, fully glycosylated envelope protein product, since western blot staining with anti-HERV-Wenv antibody detected two bands of the same molecular weight (73 and 61kDa) of the fully glycosylated and partially glycosylated HERV-Wenv uncleaved proteins. Beyond MSRVenv DNA copy numbers were more abundant in MS patients than in healthy humans, while syncytin-1 were unchanged. These findings reinforce the link between MSRV and MS.