Pierre Portales

CD4+ T Cell Surface CCR5 Density as a Determining Factor of Virus Load in Persons Infected with Human Immunodeficiency Virus Type 1

The intensity of expression of the chemokine receptor CCR5 is involved in in vitro cell infectability by human immunodeficiency virus (HIV)-1 R5 isolates. Because CCR5 expression varies among individuals, the hypothesis that this expression could determine virus load in HIV-1-infected persons was tested. The mean number of CCR5 molecules per cell was measured on peripheral blood CD4+ T lymphocytes (CCR5 density) from HIV-1-infected, asymptomatic, nontreated adults. There was a strong correlation between HIV RNA plasma level and CCR5 density (P=.009) that was independent of cell activation and was not due to an HIV-induced CCR5 up-regulation. These data are compatible with the hypothesis that CCR5 density is a key factor governing cell infectability and in vivo virus production and explain the protective effect of the Delta32CCR5 deletion, which results in low CCR5 expression. CCR5 density might be of critical predictive value in HIV infection.

Cell surface CCR5 density determines the postentry efficiency of R5 HIV-1 infection

We have recently reported that the mean number of CCR5 coreceptors at the surface of CD4+ T cells (CCR5 density) correlates with viral load and disease progression in HIV-1-infected persons. Here, we definitively establish that CCR5 density determines the level of virus production and identify the stages of HIV-1 replicative cycle modulated by this effect. We show, by transducing the CCR5 gene into CCR5+ cells, that CCR5 overexpression resulted in an HIV-1 overinfectability. We sorted HOS-CD4+-CCR5+ cells into two subpopulations, HOShigh and HOSlow, the former expressing seven times more cell surface CCR5 molecules than the latter. Virus production was 30–80 times higher in HOShigh cells than in HOSlow cells after a single round of infection. In contrast, only twice as many viral particles entered the cytosol of HOShigh cells as compared with the cytosol of HOSlow cells. Yet, seven times as many early, and 24 times as many late, reverse transcription products were found in HOShigh cells as compared with HOSlow cells. Moreover, a 24- to 30-fold difference in the number of copies of integrated HIV-1 DNA was observed. No difference in HIV-1 LTR activation between the two cell lines was evident. Finally, we show that the higher virus production observed in HOShigh cells is inhibited by pertussis toxin, a Gαi protein inhibitor. Thus, CCR5 density mainly modulates postentry steps of the virus life cycle, particularly the reverse transcription. These data explain why CCR5 density influences HIV-1 disease progression and underline the therapeutic interest of lowering CCR5 expression.

CD4 T cell surface CCR5 density as a host factor in HIV-1 disease progression.

Objective and designWe have recently shown that the number of CCR5 molecules at the surface of peripheral blood CD4 T cells (CCR5 density) correlates with the viral RNA plasma level in HIV-1-infected individuals. As viral load is a strong predictor of outcome in HIV infection, the present study examines the correlation between CCR5 density and HIV-1 disease progression. MethodsUsing a quantitative flow cytometry assay, we measured CCR5 density in HIV-1-infected adults and control healthy volunteers. The CCR5 genotype (presence of a Δ32 allele) was also determined. ResultsCCR5 density was stable over time on non-activated, HLA-DR−CD4 T cells of infected individuals. In a study cohort of 25 patients, asymptomtic and non-treated, we observed a correlation between CCR5 density on HLA-DR−CD4 T cells and the CD4 T cell slope (P = 0.026), which was independent of the presence or absence of the Δ32CCR5 deletion. In particular, slow progressors expressed lower CCR5 densities than non-slow progressors (P = 0.004) and non-infected control subjects (P = 0.002). ConclusionThese results are compatible with the hypothesis that CCR5 density, which is a key factor of HIV-1 infectability, determines in-vivo HIV production, and thereby the rate of CD4 cell decline. Consequently, CCR5 density quantitation could be a new valuable prognostic tool in HIV-1 infection. Moreover, these data emphasize the therapeutic potential of treatments that reduce functional CCR5 density.

Small-Molecule Inhibition of HIV pre-mRNA Splicing as a Novel Antiretroviral Therapy to Overcome Drug Resistance

The development of multidrug-resistant viruses compromises antiretroviral therapy efficacy and limits therapeutic options. Therefore, it is an ongoing task to identify new targets for antiretroviral therapy and to develop new drugs. Here, we show that an indole derivative (IDC16) that interferes with exonic splicing enhancer activity of the SR protein splicing factor SF2/ASF suppresses the production of key viral proteins, thereby compromising subsequent synthesis of full-length HIV-1 pre-mRNA and assembly of infectious particles. IDC16 inhibits replication of macrophage- and T cell–tropic laboratory strains, clinical isolates, and strains with high-level resistance to inhibitors of viral protease and reverse transcriptase. Importantly, drug treatment of primary blood cells did not alter splicing profiles of endogenous genes involved in cell cycle transition and apoptosis. Thus, human splicing factors represent novel and promising drug targets for the development of antiretroviral therapies, particularly for the inhibition of multidrug-resistant viruses.

Low dose antithymocyte globulins in renal transplantation: daily versus intermittent administration based on T-cell monitoring.

BACKGROUND Despite the long history of use of antithymocyte globulins (ATG) in renal transplantation, ideal doses and duration of ATG administration based on the monitoring of T lymphocytes have yet to be defined. METHODS Two immunosuppressive regimens based on low-dose rabbit ATG (Thymoglobuline; Imtix-Sang-stat, Lyon, France) were assessed during the first year after transplantation: daily ATG (DATG; n=23) where 50 mg of ATG was given every day and intermittent ATG (IATG; n=16) where similar doses of ATG were given for the first 3 days and then intermittently only if CD3+ T lymphocytes (measured by flow cytometry) were > 10/mm3. Both groups received steroids, azathioprine, and cyclosporine. RESULTS ATG-induced depletion was similar for peripheral blood lymphocytes and T cells in both groups: it began at day 1 after transplantation, was submaximal at day 3, and reached maximum intensity between days 6 and 8, from which time cell counts progressively increased. However, T-cell depletion was still present at day 20. The total ATG dose per patient (381.5+/-121 vs. 564+/-135 mg/patient) and the mean cumulative daily dose of ATG (0.60+/-0.17 vs. 0.80+/-0.14 mg/kg/day) were significantly lower in the IATG group (P=0.0001 and 0.0006, respectively). The overlap of ATG and cyclosporine treatment was 6.7+/-3 vs. 7.4+/-4.3 days (P=NS), and the mean duration of ATG therapy was 11.3+/-3.2 vs. 11.6+/-2.7 days in the IATG and DATG groups, respectively (P=NS). ATG was given in an average of one dose every 1.6 days in the IATG group compared with one dose daily in the DATG group (P=7 x 10(-7)). There was no significant difference in renal graft function, the number of acute graft rejections, or ATG-related side effects and complications. Despite the daily immunological follow-up, there was a net saving of

A3.10 IL-6 Receptor Blockade Enhances CD39+ Regulatory T-Cell Development in Rheumatoid Arthritis and in Experimental Arthritis

760/patient in the cost of treatment in the IATG group. CONCLUSION IATG had the advantage of a reduction in the dose of ATG and in the cost of treatment, while offering similar T-cell depletion and effective immunosuppression. This approach could be proposed as an induction protocol, particularly for patients with poor graft function in whom cyclosporine introduction has to be delayed or those with increased risk of cytomegalovirus infections or secondary malignancies.

A new autoinflammatory and autoimmune syndrome associated with NLRP1 mutations: NAIAD (NLRP1-associated autoinflammation with arthritis and dyskeratosis)

Background and Objectives Studies have demonstrated the clinical efficacy of tocilizumab, a humanised anti-IL-6 receptor (R) antibody (Ab), in patients with rheumatoid arthritis (RA). The rational for blocking IL-6 in this disease mainly lays on the pro-inflammatory role of this cytokine in the disease. However, only few works have studied the consequences of anti-IL-6R treatment on Tregs cells and mainly focuses on their frequency. Our objective was to elucidate anti-IL-6R mode of action on Tregs in RA patients treated with tocilizumab and in a RA model. Methods Mice with collagen-induced arthritis (CIA) were treated at day 0 by MR16–1 (a rat anti-mouse IL-6 receptor monoclonal Ab provided by Chugai Pharmaceutical Co. LTD, Japan) and the evolution of CD4+ FoxP3+ Tregs during arthritis course was assessed at key time points (day 8–18–28 and 42 after CIA induction) by studying their number, frequency and phenotype (expression of GITR, ICOS, Helios, CD62L, CTLA-4 and CD39) in lymph nodes (LN), thymus and spleen by flow cytometry. Numerical analysis of Th17 and Th1 cells was also performed by flow cytometry. Twenty patients with severe and active RA were recruited and treated with 8 mg/kg of tocilizumab monthly. Peripheral blood was recovered at day 0, as well as 1 and 3 month, and Th17and Tregs were analysed by flow cytometry. Results Clinical and histological evaluation of arthritides in mice treated with anti-mouse IL-6R mAb showed, as expected, a less severe disease as compared to control Ig treated mice. Th17 frequency was unchanged, but Tregs frequency was enhanced in the LN of MR16–1 treated mice. In the thymus, we observed an enhanced frequency of Tregs CD4+CD8−FoxP3+. Tregs phenotype was also modified in treated mice, with an increased frequency of CD39+ Tregs (LN and spleen), suggesting an enhanced ATP hydrolysis immunosuppressive activity of Tregs. In RA patients, Th17 frequencies were not modified by tocilizumab therapy and did not differ between responders and non-responders. Interestingly, CD39+ Treg cell among CD4+ cells frequencies were significantly higher in responders than in non-responders after 3 months of tocilizumab therapy. Conclusions Tregs, but not Th17, are modified by anti-IL-6R treatment in both CIA and RA. These results support a beneficial effect in RA of treatments responsible for CD39+ Tregs enhancement and emphasise the relevance of the monitoring cell populations after cytokine blockade used to treat arthritis.

Response to Treatment and Disease Progression Linked to CD4+ T Cell Surface CC Chemokine Receptor 5 Density in Human Immunodeficiency Virus Type 1 Vertical Infection

Objectives Inflammasomes are multiprotein complexes that sense pathogens and trigger biological mechanisms to control infection. Nucleotide-binding oligomerisation domain-like receptor (NLR) containing a PYRIN domain 1 (NLRP1), NLRP3 and NLRC4 plays a key role in this innate immune system by directly assembling in inflammasomes and regulating inflammation. Mutations in NLRP3 and NLRC4 are linked to hereditary autoinflammatory diseases, whereas polymorphisms in NLRP1 are associated with autoimmune disorders such as vitiligo and rheumatoid arthritis. Whether human NLRP1 mutation is associated with autoinflammation remains to be determined. Methods To search for novel genes involved in systemic juvenile idiopathic arthritis, we performed homozygosity mapping and exome sequencing to identify causative genes. Immunoassays were performed with blood samples from patients. Results We identified a novel disease in three patients from two unrelated families presenting diffuse skin dyskeratosis, autoinflammation, autoimmunity, arthritis and high transitional B-cell level. Molecular screening revealed a non-synonymous homozygous mutation in NLRP1 (c.2176C>T; p.Arg726Trp) in two cousins born of related parents originating from Algeria and a de novo heterozygous mutation (c.3641C>G, p.Pro1214Arg) in a girl of Dutch origin. The three patients showed elevated systemic levels of caspase-1 and interleukin 18, which suggested involvement of NLRP1 inflammasome. Conclusions We demonstrate the responsibility of human NLRP1 in a novel autoinflammatory disorder that we propose to call NAIAD for NLRP1-associated autoinflammation with arthritis and dyskeratosis. This disease could be a novel autoimmuno-inflammatory disease combining autoinflammatory and autoimmune features. Our data, combined with that in the literature, highlight the pleomorphic role of NLRP1 in inflammation and immunity. Trial registration number NCT02067962; Results.

The strength of the chemotactic response to a CCR5 binding chemokine is determined by the level of cell surface CCR5 density

The factors governing interindividual variability in disease progression among children vertically infected with human immunodeficiency virus type 1 (HIV-1) remain unclear. Because it has recently been shown in infected adults that the density of CC chemokine receptor 5 (CCR5) molecules at the surface of nonactivated (human leukocyte antigen [HLA]-DR(-)) CD4+ T cells correlates with disease progression, the same correlation was sought in children. HLA-DR(-)CD4+ T cell surface CCR5 density was constant over time and correlated with the bioclinical stage and with the CD4 cell slope observed before antiretroviral treatment. In addition, CCR5 density was negatively correlated with the intensity of the decrease in viremia during antiretroviral therapy and was positively correlated with CD4 cell slope since birth. These results are compatible with the hypothesis that CCR5 density is a key factor governing disease progression in pediatric HIV-1 infection and, thereby, an indicator of prognosis. Moreover, they suggest that therapies aimed at reducing CCR5 accessibility should slow down HIV disease evolution in children.

G-Protein Signaling Triggered by R5 Human Immunodeficiency Virus Type 1 Increases Virus Replication Efficiency in Primary T Lymphocytes

We have shown that the intensity of expression of the C‐C chemokine receptor CCR5 at the single CD4+ cell level strongly determines the efficiency of its function as a coreceptor for human immunodeficiency virus type 1. By analogy, we examined if the number of CCR5 molecules at the cell surface might determine its chemotactic response to CCR5 ligands. To test this hypothesis, we measured by flow cytometry the migration of primary human T cells towards the CCR5‐binding chemokine CCL5 in vitro. First, we observed a dose‐dependent blockage of this migration exerted by an anti‐CCR5 monoclonal antibody. Second, we sorted peripheral blood mononuclear cells into five subpopulations expressing various cell surface CCR5 densities, and observed a correlation between the intensity of migration towards CCL5 and the level of CCR5 expression on these subpopulations. Third, we transduced CCR5+ peripheral blood mononuclear cells with the CCR5 gene, and observed that the CCR5 over‐expression induced an over‐migration towards CCL5. Finally, we observed in healthy donors a correlation between the chemotactic response of peripheral blood CD8+ T cell to CCL5 and their level of surface CCR5 expression. T‐cell surface CCR5 density, which is constant over time for a given individual, but varies drastically among individuals, might therefore be an important personal determinant of T‐cell migration in many biological situations where CCR5‐binding chemokines play a role, such as graft rejection, T helper 1‐mediated auto‐immune diseases, and infectious diseases involving CCR5. Moreover, our data highlight the therapeutic potential of CCR5 antagonists in these situations.