Flow cytometric assay detecting cytotoxicity against human endogenous retrovirus antigens expressed on cultured multiple sclerosis cells

Regulation of the expression of human endogenous retroviruses: elements in fetal development and a possible role in the development of cancer and neurological diseases

Human endogenous retroviruses (HERVs) are remnants of ancient retroviral germline infections. Most HERV sequences are silenced in somatic cells, but interest is emerging on the involvement of HERV derived transcripts and proteins in human physiology and disease. A HERV-W encoded protein, syncytin-1, has been co-opted into fetal physiology, where it plays a role in trophoblast formation. Altered HERV transcription and expression of HERV derived proteins are associated with various cancer types and neurological diseases such as multiple sclerosis (MS). The implication of HERVs as potential mediators of both health and disease suggests important roles of regulatory mechanisms and alterations of these in physiological and pathological processes. The regulation of HERV sequences is mediated by a wide variety of mechanisms, and the focus of this review is on selected aspects of these, including epigenetic mechanisms such as CpG methylation and histone modifications of the HP1-H3K9me axis, viral transactivation events, and regulatory perspectives of transient stimuli in the microenvironment. Increasing knowledge of the regulation of HERV sequences will not only contribute to the understanding of complex pathogeneses, but also may pinpoint potential targets for better diagnosis and treatment in complex diseases as MS.

A phase II baseline versus treatment study to determine the efficacy of raltegravir (Isentress) in preventing progression of relapsing remitting multiple sclerosis as determined by gadolinium-enhanced MRI: The INSPIRE study

BACKGROUND

Although the aetiology of multiple sclerosis (MS) remains elusive, it is clear that Epstein Barr virus (EBV) and possibly other viruses play a role in the pathogenesis of MS. Laboratory evidence suggests that human endogenous retroviruses (HERVs) could also have a role, but no interventional therapy has determined what will happen if HERVs are suppressed. Recent epidemiological evidence indicates patients with HIV infection have a significantly lower risk of developing MS and that HIV antiretroviral therapies may be coincidentally inhibiting HERVs, or other retroelements, that could be implicated in MS.

OBJECTIVES

To systematically investigate the effects of an HIV integrase strand inhibitor, raltegravir, on the number of gadolinium (Gd)-enhanced MRI lesions in people with active relapsing MS.

METHODS

This is a Phase 2a clinical trial where twenty participants were enrolled in a 3 month baseline phase followed by 3 months of treatment with raltegravir 400 mg twice a day. Patients had monthly Gd-enhanced MRI, saliva collection to test for EBV shedding, blood sampling for safety monitoring, virology (including HERVs), measurement of immunological and inflammatory markers; and physical, neurological and quality-of-life assessments.

RESULTS

All patients completed the six months trial period.The primary outcome measure of MS disease activity was the number of Gd-enhancing lesions observed, and raltegravir had no significant effect on the rate of development of Gd-enhancing lesions during the treatment phase compared with the baseline phase. Additionally, there was no change in secondary outcomes of either disability or quality-of-life measures that could reasonably be attributed to the intervention. There was a significant positive between HERV-W/MSRV (multiple sclerosis related virus) Gag Flix (Fluorescence index) B cells and the number of Gd-enhanced lesions at any visit (p = 0.029), which was independent of any potential influence of the trial drug administration. Regarding EBV shedding, there was no significant correlation between the amount of EBV shedding and the number of lesions. No change was detected in inflammatory markers (IL-8, IL-1β, IL-6, IL-10, TNF, IL-12p70 and HCRP), which were all within normal limits both before and after the intervention. Serum CD163 expression was also unchanged by raltegravir.

CONCLUSIONS

Raltegravir did not have any impact on MS disease activity. This could be due to the choice of antiretroviral agent used in this study, the need for a combination of agents, as used in treating HIV infection, the short treatment period or dosing regimen, or the lack of a role of HERV expression in MS once the disease is established. Borderline significance for the association between EBV shedding and the total number of lesions, probably driven by new lesion development, may indicate EBV shedding as a marker of inflammatory disease activity. In conclusion, interesting correlations between HERV-W markers, EBV shedding and new MRI lesions, independent from treatment effects, were found.

Natural killer cells in malignant hematology: A primer for the non-immunologist

Natural killer cells were first described over 40years ago, but the last 15years has shown tremendous progress in our understanding of their biology and our ability to manipulate them for clinical therapeutic effect. Despite the increased understanding by clinicians and scientists investigating these cells, their biology remains a confusing subject for many because of the wide array of receptors, complex interactions, multiple models of predicting function, and contradictory data in the literature. While they are microscopically indistinguishable from T cells and share many of the same effector functions, their mechanisms of target recognition are completely distinct from yet complimentary to T cells. In this review we provide a basic understanding of NK cell biology and HLA recognition as compared and contrasted to T cells using a metaphor of border patrol and passports. We conclude with a summary of the evidence for NK cell effects in hematologic malignancies and describe new advances in NK cell immunotherapy aimed at improving these effects.

A novel method for evaluating antibody-dependent cell-mediated cytotoxicity by flowcytometry using cryopreserved human peripheral blood mononuclear cells

Analyzing the cytotoxic functions of effector cells, such as NK cells against target cancer cells, is thought to be necessary for predicting the clinical efficacy of antibody-dependent cellular cytotoxicity (ADCC) -dependent antibody therapy. The (51)Cr release assay has long been the most widely used method for quantification of ADCC activity. However, the reproducibilities of these release assays are not adequate, and they do not allow evaluation of the lysis susceptibilities of distinct cell types within the target cell population. In this study, we established a novel method for evaluating cytotoxicity, which involves the detection and quantification of dead target cells using flowcytometry. CFSE (carboxyfluorescein succinimidyl ester) was used as a dye to specifically stain and thereby label the target cell population, allowing living and dead cells, as well as both target and effector cells, to be quantitatively distinguished. Furthermore, with our new approach, ADCC activity was more reproducibly, sensitively, and specifically detectable, not only in freshly isolated but also in frozen human peripheral blood mononuclear cells (PBMCs), than with the calcein-AM release assay. This assay, validated herein, is expected to become a standard assay for evaluating ADCC activity which will ultimately contribute the clinical development of ADCC dependent-antibody therapies.