Immune response to pertussis vaccine in COPD patients

Exacerbation triggered by respiratory infection is an important cause of morbidity and mortality in chronic obstructive pulmonary disease (COPD) patients. Strategies aiming to preventing infection may have significant public health impact. Our previous study demonstrated decreased immunological response to seasonal flu vaccination in COPD patients, questioning the efficiency of other vaccines in this group of patients. We performed a prospective, monocenter, longitudinal study that evaluated the humoral and cellular responses upon pertussis vaccination. We included 13 patients with stable COPD and 8 healthy volunteers. No difference in circulating B and T cell subsets at baseline was noted. Both groups presented similar levels of TFH, plasmablasts and pertussis specific antibodies induction after vaccination. Moreover, monitoring T cell immunity after ex-vivo peptide stimulation revealed equivalent induction of functional and specific CD4+ T cells (IFNγ, TNFα and IL-2-expressing T cells) in both groups. Our results highlight the immunological efficiency of pertussis vaccination in this particularly vulnerable population and challenge the concept that COPD patients are less responsive to all immunization strategies. Healthcare providers should stress the necessity of decennial Tdap booster vaccination in COPD patients.

Differences in HIV cure clinical trial preferences of French people living with HIV and physicians in the ANRS-APSEC study: a discrete choice experiment

INTRODUCTION

Despite the advent of HIV cure-related clinical trials (HCRCT) for people living with HIV (PLWH), the risks and uncertainty involved raise ethical issues. Although research has provided insights into the levers and barriers to PLWH and physicians' participation in these trials, no information exists about stakeholders' preferences for HCRCT attributes, about the different ways PLWH and physicians value future HCRCT, or about how personal characteristics affect these preferences. The results from the present study will inform researchers' decisions about the most suitable HCRCT strategies to implement, and help them ensure ethical recruitment and well-designed informed consent.

METHODS

Between October 2016 and March 2017, a discrete choice experiment was conducted among 195 virally controlled PLWH and 160 physicians from 24 French HIV centres. Profiles within each group, based on individual characteristics, were obtained using hierarchical clustering. Trade-offs between five HCRCT attributes (trial duration, consultation frequency, moderate (digestive disorders, flu-type syndrome, fatigue) and severe (allergy, infections, risk of cancer) side effects (SE), outcomes) and utilities associated with four HCRCT candidates (latency reactivation, immunotherapy, gene therapy and a combination of latency reactivation and immunotherapy), were estimated using a mixed logit model.

RESULTS

Apart from severe SE - the most decisive attribute in both groups - PLWH and physicians made different trade-offs between HCRCT attributes, the latter being more concerned about outcomes, the former about the burden of participation (consultation frequency and moderate SE). These different trades-offs resulted in differences in preferences regarding the four candidate HCRCT. PLWH significantly preferred immunotherapy, whereas physicians preferred immunotherapy and combined therapy. Despite the heterogeneity of characteristics within the PLWH and physician profiles, results show some homogeneity in trade-offs and utilities regarding HCRCT.

CONCLUSIONS

Severe SE, not outcomes, was the most decisive attribute determining future HCRCT participation. Particular attention should be paid to providing clear information, in particular on severe SE, to potential participants. Immunotherapy would appear to be the best HCRCT candidate for both PLWH and physicians. However, if the risk of cancer could be avoided, gene therapy would become the preferred strategy for the latter and the second choice for the former.

Effects of recombinant human interleukin 7 on T-cell recovery and thymic output in HIV-infected patients receiving antiretroviral therapy: results of a phase I/IIa randomized, placebo-controlled, multicenter study

BACKGROUND

The immune deficiency of human immunodeficiency virus (HIV) infection is not fully corrected with ARV therapy. Interleukin-7 (IL-7) can boost CD4 T-cell counts, but optimal dosing and mechanisms of cellular increases need to be defined.

METHODS

We performed a randomized placebo-controlled dose escalation (10, 20 and 30 µg/kg) trial of 3 weekly doses of recombinant human IL-7 (rhIL-7) in ARV-treated HIV-infected persons with CD4 T-cell counts between 101 and 400 cells/µL and plasma HIV levels <50 copies/mL. Toxicity, activity and the impact of rhIL-7 on immune reconstitution were monitored.

RESULTS

Doses of rhIL-7 up to 20 µg/kg were well tolerated. CD4 increases of predominantly naive and central memory T cells were brisk (averaging 323 cells/µL at 12 weeks) and durable (up to 1 year). Increased cell cycling and transient increased bcl-2 expression were noted. Expanded cells did not have the characteristics of regulatory or activated T cells. Transient low-level HIV viremia was seen in 6 of 26 treated patients; modest increases in total levels of intracellular HIV DNA were proportional to CD4 T-cell expansions. IL-7 seemed to increase thymic output and tended to improve the T-cell receptor (TCR) repertoire in persons with low TCR diversity.

CONCLUSIONS

Three weekly doses of rhIL-7 at 20 µg/kg are well tolerated and lead to a dose-dependent CD4 T-cell increase and the broadening of TCR diversity in some subjects. These data suggest that this rhIL-7 dose could be advanced in future rhIL-7 clinical studies.

CLINICAL TRIALS REGISTRATION

NCT0047732.

A novel mechanism for HIV1-mediated bystander CD4+ T-cell death: neighboring dying cells drive the capacity of HIV1 to kill noncycling primary CD4+ T cells

CD4+ T-cell death is a crucial feature of AIDS pathogenesis, but the mechanisms involved remain unclear. Here, we present in vitro findings that identify a novel process of HIV1 mediated killing of bystander CD4+ T cells, which does not require productive infection of these cells but depends on the presence of neighboring dying cells. X4-tropic HIV1 strains, which use CD4 and CXCR4 as receptors for cell entry, caused death of unstimulated noncycling primary CD4+ T cells only if the viruses were produced by dying, productively infected T cells, but not by living, chronically infected T cells or by living HIV1-transfected HeLa cells. Inducing cell death in HIV1-transfected HeLa cells was sufficient to obtain viruses that caused CD4+ T-cell death. The addition of supernatants from dying control cells, including primary T cells, allowed viruses produced by living HIV1-transfected cells to cause CD4+ T-cell death. CD4+ T-cell killing required HIV1 fusion and/or entry into these cells, but neither HIV1 envelope-mediated CD4 or CXCR4 signaling nor the presence of the HIV1 Nef protein in the viral particles. Supernatants from dying control cells contained CD95 ligand (CD95L), and antibody-mediated neutralization of CD95L prevented these supernatants from complementing HIV1 in inducing CD4+ T-cell death. Our in vitro findings suggest that the very extent of cell death induced in vivo during HIV1 infection by either virus cytopathic effects or immune activation may by itself provide an amplification loop in AIDS pathogenesis. More generally, they provide a paradigm for pathogen-mediated killing processes in which the extent of cell death occurring in the microenvironment might drive the capacity of the pathogen to induce further cell death.

Caspase-dependent and -independent T-cell death pathways in pathogenic simian immunodeficiency virus infection: relationship to disease progression

Studies of human immunodeficiency virus (HIV) and nonhuman primate models of pathogenic and nonpathogenic simian immunodeficiency virus (SIV) infections have suggested that enhanced ex vivo CD4 T-cell death is a feature of pathogenic infection in vivo. However, the relative contributions of the extrinsic and intrinsic pathways to programmed T-cell death in SIV infection have not been studied. We report here that the spontaneous death rate of CD4+ T cells from pathogenic SIVmac251-infected rhesus macaques ex vivo is correlated with CD4 T-cell depletion and plasma viral load in vivo. CD4+ T cells from SIVmac251-infected macaques showed upregulation of the death ligand (CD95L) and of the proapoptotic proteins Bim and Bak, but not of Bax. Both CD4+ and CD8+ T cells from SIVmac251-infected macaques underwent caspase-dependent death following CD95 ligation. The spontaneous death of CD4+ and CD8+ T cells was not prevented by a decoy CD95 receptor or by a broad-spectrum caspase inhibitor (zVAD-fmk), suggesting that this form of cell death is independent of CD95/CD95L interaction and caspase activation. IL-2 and IL-15 prevented the spontaneous death of CD4+ and CD8+ T cells, whereas IL-10 prevented only CD8 T-cell death and IL-7 had no effect on T-cell death. Our results indicate that caspase-dependent and caspase-independent pathways are involved in the death of T cells in pathogenic SIVmac251-infected primates.

Possible mechanism of toxicity of zidovudine by induction of apoptosis of CD4+ and CD8+ T-cells in vivo

Some HIV-infected patients have a discordant response to highly active antiretroviral therapy with a low virus load and an incomplete restoration of CD4+ T-cell counts. Zidovudine may limit CD4+ restoration by a hematotoxic mechanism. Apoptosis and T-cell counts were assessed in two patients before and after they switched from zidovudine to stavudine. Whereas CD4+ T-cell apoptosis fell from 52% and 66% before the zidovudine switch to 7% and 12%, respectively, after the switch, the patients' CD4+ counts rose gradually to +183 and +150 cells, respectively. It was therefore hypothesized that zidovudine directly induced apoptosis. Zidovudine withdrawal could be tested before immunological interventions such as interleukin-2 therapy are considered.

Role of CD95-activated caspase-1 processing of IL-1beta in TCR-mediated proliferation of HIV-infected CD4(+) T cells

CD95 plays a critical role in the homeostasis of the immune system, and has been reported to participate in T cell death during HIV infection. Here we report that the response to CD3-TCR stimulation of CD4(+) T cells from HIV-infected individuals and CD4(+) T cells from healthy donors incubated in vitro with HIV-1(Lai) depends on the manner the CD3-TCR complex is engaged. While stimulation by anti-CD3 antibodies in solution induced CD4 T cell apoptosis both in the absence or presence of anti-CD95 antibodies, stimulation by immobilized anti-CD3 antibodies rendered CD4(+) T cells resistant to CD95-mediated death and led to increased CD4 T cell proliferation in response to CD95 ligation. CD95 ligation of CD4(+) T cells led to the activation of caspases, while costimulation induced by anti-CD3 and anti-CD95 mAb prevented the full processing of caspase-3 and caspase-8. Proliferation of CD4(+) T cells induced by CD3-TCR and CD95 costimulation was decreased by treatments with a caspase-1 inhibitor or with neutralizing antibodies to IL-1ss, indicating a requirement for caspase-1-mediated IL-1beta processing and secretion. Our findings suggest a novel mechanism whereby in addition to its role in inducing T cell apoptosis, CD95 signaling during HIV infection may also provide a costimulatory signal leading to an enhancement of CD4 T cell proliferation in response to CD3-TCR complex engagement.