Antigen-independent induction of Tim-3 expression on human T cells by the common γ-chain cytokines IL-2, IL-7, IL-15, and IL-21 is associated with proliferation and is dependent on the phosphoinositide 3-kinase pathway.

T cell Ig mucin domain-containing molecule 3 (Tim-3) is a glycoprotein found on the surface of a subset of CD8(+) and Th1 CD4(+) T cells. Elevated expression of Tim-3 on virus-specific T cells during chronic viral infections, such as HIV-1, hepatitis B virus, and hepatitis C virus, positively correlates with viral load. Tim-3(+) cytotoxic T cells are dysfunctional and are unable to secrete effector cytokines, such as IFN-γ and TNF-α. In this study, we examined potential inducers of Tim-3 on primary human T cells. Direct HIV-1 infection of CD4(+) T cells, or LPS, found to be elevated in HIV-1 infection, did not induce Tim-3 on T cells. Tim-3 was induced by the common γ-chain (γc) cytokines IL-2, IL-7, IL-15, and IL-21 but not IL-4, in an Ag-independent manner and was upregulated on primary T cells in response to TCR/CD28 costimulation, as well as γc cytokine stimulation with successive divisions. γc cytokine-induced Tim-3 was found on naive, effector, and memory subsets of T cells. Tim-3(+) primary T cells were more prone to apoptosis, particularly upon treatment with galectin-9, a Tim-3 ligand, after cytokine withdrawal. The upregulation of Tim-3 could be blocked by the addition of a PI3K inhibitor, LY 294002. Thus, Tim-3 can be induced via TCR/CD28 costimulation and/or γc cytokines, likely through the PI3K pathway.

Process Evaluation of a Hub-and-Spoke Model to Deliver Coordinated Care for Children with Medical Complexity across Ontario: Facilitators, Barriers and Lessons Learned.

BACKGROUND: Complex Care for Kids Ontario (CCKO) is a multi-year strategy aimed at expanding a hub-and-spoke model to deliver coordinated care for children with medical complexity (CMC) across Ontario. OBJECTIVE: This paper aims to identify the facilitators, barriers and lessons learned from the implementation of the Ontario CCKO strategy. METHOD: Alongside an outcome evaluation of the CCKO strategy, we conducted a process evaluation to understand the implementation context, process and mechanisms. Semi-structured interviews were conducted with 38 healthcare leaders, clinicians and support staff from four regions involved in CCKO care delivery and/or governance. RESULTS: Facilitators to CCKO implementation were sustained engagement of system-wide stakeholders, inter-organizational partnerships, knowledge sharing and family engagement. Barriers to CCKO implementation were resources and funding, fragmentation of care, aligning perspectives between providers and clinical staff recruitment and retention. CONCLUSION: A flexible approach is required to implement a complex, multi-centre policy strategy. Other jurisdictions considering such a model of care delivery would benefit from attention to contextual variations in implementation setting, building cross-sector engagement and buy-in, and offering continuous support for modifications to the intervention as and when required.

Pharmacologic HIV-1 Nef blockade promotes CD8 T cell-mediated elimination of latently HIV-1-infected cells in vitro.

Eradication of the HIV-1 latent reservoir represents the current paradigm to developing a cure for AIDS. HIV-1 has evolved multiple mechanisms to evade CD8 T cell responses, including HIV-1 Nef-mediated downregulation of MHC-I from the surface of infected cells. Nef transcripts and protein are detectable in samples from aviremic donors, suggesting that Nef expression in latently HIV-1-infected CD4 T cells protects them from immune-mediated clearance. Here, we tested 4 small molecule inhibitors of HIV-1 Nef in an in vitro primary CD4 T cell latency model and measured the ability of autologous ex vivo or HIV-1 peptide-expanded CD8 T cells to recognize and kill latently infected cells as a function of inhibitor treatment. Nef inhibition enhanced cytokine secretion by autologous CD8 T cells against latently HIV-1-infected targets in an IFN-γ release assay. Additionally, CD8 T cell-mediated elimination of latently HIV-1-infected cells was significantly enhanced following Nef blockade, measured as a reduction in the frequency of infected cells and Gag protein in cultures following viral outgrowth assays. We demonstrate for the first time to our knowledge that Nef blockade, in combination with HIV-specific CD8 T cell expansion, might be a feasible strategy to target the HIV-1 latent reservoir that should be tested further in vivo.

In Women's Eyes: Key Barriers to Women's Access to HIV Treatment and a Rights-Based Approach to their Sustained Well-Being.

There is rightly a huge global effort to enable women living with HIV to have long productive lives, through treatment access. However, many women living with HIV experience violence against women (VAW), in both domestic and health care settings. The ways in which VAW might prevent treatment access and adherence for women has not to date been reviewed coherently at the global level, from women's own perspectives. Meanwhile, funding for global health care, including HIV treatment, is shrinking. To optimize women's health and know how best to optimize facilitators and minimize barriers to access and adherence, especially in this shrinking funding context, we need to understand more about these issues from women's own perspectives. In response, we conducted a three-phase review: (1) a literature review (phase one); (2) focus group discussions and interviews with nearly 200 women living with HIV from 17 countries (phase two); and (3) three country case studies (phase three). The results presented here are based predominantly on women's own experiences and are coherent across all three phases. Recommendations are proposed regarding laws, policies, and programs which are rights-based, gendered, and embrace diversity, to maximize women's voluntary, informed, confidential, and safe access to and adherence to medication, and optimize their long-term sexual and reproductive health.

HIV delays IFN-α production from human plasmacytoid dendritic cells and is associated with SYK phosphorylation.

Plasmacytoid dendritic cells (pDC) are the major producers of type I interferons (IFNs) in humans and rapidly produce IFN-α in response to virus exposure. Although HIV infection is associated with pDC activation, it is unclear why the innate immune response is unable to effectively control viral replication. We systematically compared the effect of HIV, Influenza, Sendai, and HSV-2 at similar target cell multiplicity of infection (M.O.I.) on human pDC function. We found that Influenza, Sendai, HSV-2 and imiquimod are able to rapidly induce IFN-α production within 4 hours to maximal levels, whereas HIV had a delayed induction that was maximal only after 24 hours. In addition, maximal IFN-α induction by HIV was at least 10 fold less than that of the other viruses in the panel. HIV also induced less TNF-α and MIP-1ß but similar levels of IP-10 compared to other viruses, which was also mirrored by delayed upregulation of pDC activation markers CD83 and CD86. BDCA-2 has been identified as an inhibitory receptor on pDC, signaling through a pathway that involves SYK phosphorylation. We find that compared to Influenza, HIV induces the activation of the SYK pathway. Thus, HIV delays pDC IFN-α production and pDC activation via SYK phosphorylation, allowing establishment of viral populations.

Loss of the signaling adaptor TRAF1 causes CD8+ T cell dysregulation during human and murine chronic infection.

The signaling adaptor TNFR-associated factor 1 (TRAF1) is specifically lost from virus-specific CD8 T cells during the chronic phase of infection with HIV in humans or lymphocytic choriomeningitis virus (LCMV) clone 13 in mice. In contrast, TRAF1 is maintained at higher levels in virus-specific T cells of HIV controllers or after acute LCMV infection. TRAF1 expression negatively correlates with programmed death 1 expression and HIV load and knockdown of TRAF1 in CD8 T cells from viral controllers results in decreased HIV suppression ex vivo. Consistent with the desensitization of the TRAF1-binding co-stimulatory receptor 4-1BB, 4-1BBL-deficient mice have defects in viral control early, but not late, in chronic infection. TGFß induces the posttranslational loss of TRAF1, whereas IL-7 restores TRAF1 levels. A combination treatment with IL-7 and agonist anti-4-1BB antibody at 3 wk after LCMV clone 13 infection expands T cells and reduces viral load in a TRAF1-dependent manner. Moreover, transfer of TRAF1(+) but not TRAF1(-) memory T cells at the chronic stage of infection reduces viral load. These findings identify TRAF1 as a potential biomarker of HIV-specific CD8 T cell fitness during the chronic phase of disease and a target for therapy.

HERV-K-specific T cells eliminate diverse HIV-1/2 and SIV primary isolates.

The genetic diversity of HIV-1 represents a major challenge in vaccine development. In this study, we establish a rationale for eliminating HIV-1-infected cells by targeting cellular immune responses against stable human endogenous retroviral (HERV) antigens. HERV DNA sequences in the human genome represent the remnants of ancient infectious retroviruses. We show that the infection of CD4+ T cells with HIV-1 resulted in transcription of the HML-2 lineage of HERV type K [HERV-K(HML-2)] and the expression of Gag and Env proteins. HERV-K(HML-2)-specific CD8+ T cells obtained from HIV-1-infected human subjects responded to HIV-1-infected cells in a Vif-dependent manner in vitro. Consistent with the proposed mode of action, a HERV-K(HML-2)-specific CD8+ T cell clone exhibited comprehensive elimination of cells infected with a panel of globally diverse HIV-1, HIV-2, and SIV isolates in vitro. We identified a second T cell response that exhibited cross-reactivity between homologous HIV-1-Pol and HERV-K(HML-2)-Pol determinants, raising the possibility that homology between HIV-1 and HERVs plays a role in shaping, and perhaps enhancing, the T cell response to HIV-1. This justifies the consideration of HERV-K(HML-2)-specific and cross-reactive T cell responses in the natural control of HIV-1 infection and for exploring HERV-K(HML-2)-targeted HIV-1 vaccines and immunotherapeutics.