Impaired CpG Demethylation in Common Variable Immunodeficiency Associates With B Cell Phenotype and Proliferation Rate.

Common Variable Immunodeficiency (CVID) is characterized by impaired antibody production and poor terminal differentiation of the B cell compartment, yet its pathogenesis is still poorly understood. We first reported the occurrence of epigenetic alterations in CVID by high-throughput methylation analysis in CVID-discordant monozygotic twins. Data from a recent whole DNA methylome analysis throughout different stages of normal B cell differentiation allowed us to design a new experimental approach. We selected CpG sites for analysis based on two criteria: one, CpGs with potential association with the transcriptional status of relevant genes for B cell activation and differentiation; and two, CpGs that undergo significant demethylation from naïve to memory B cells in healthy individuals. DNA methylation was analyzed by bisulfite pyrosequencing of specific CpG sites in sorted naïve and memory B cell subsets from CVID patients and healthy donors. We observed impaired demethylation in two thirds of the selected CpGs in CVID memory B cells, in genes that govern B cell-specific processes or participate in B cell signaling. The degree of demethylation impairment associated with the extent of the memory B cell reduction. The impaired demethylation in such functionally relevant genes as AICDA in switched memory B cells correlated with a lower proliferative rate. Our new results reinforce the hypothesis of altered demethylation during B cell differentiation as a contributing pathogenic mechanism to the impairment of B cell function and maturation in CVID. In particular, deregulated epigenetic control of AICDA could play a role in the defective establishment of a post-germinal center B cell compartment in CVID.

Maraviroc Is Associated with Latent HIV-1 Reactivation through NF-κB Activation in Resting CD4+ T Cells from HIV-Infected Individuals on Suppressive Antiretroviral Therapy.

Maraviroc is a CCR5 antagonist used in the treatment of HIV-1 infection. We and others have suggested that maraviroc could reactivate latent HIV-1. To test the latency-reversing potential of maraviroc and the mechanisms involved, we performed a phase II, single-center, open-label study in which maraviroc was administered for 10 days to 20 HIV-1-infected individuals on suppressive antiretroviral therapy (EudraCT registration no. 2012-003215-66). All patients completed full maraviroc dosing and follow-up. The primary endpoint was to study whether maraviroc may reactivate HIV-1 latency, eliciting signaling pathways involved in the viral reactivation. An increase in HIV-1 transcription in resting CD4+ T cells, estimated by levels of HIV-1 unspliced RNA, was observed. Moreover, activation of the NF-κB transcription factor was observed in these cells. To elucidate the mechanism of NF-κB activation by maraviroc, we have evaluated in HeLa P4 C5 cells, which stably express CCR5, whether maraviroc could be acting as a partial CCR5 agonist, with no other mechanisms or pathways involved. Our results show that maraviroc can induce NF-κB activity and that NF-κB targets gene expression by CCR5 binding, since the use of TAK779, a CCR5 inhibitor, blocked NF-κB activation and functionality. Taking the results together, we show that maraviroc may have a role in the activation of latent virus transcription through the activation of NF-κB as a result of binding CCR5. Our results strongly support a novel use of maraviroc as a potential latency reversal agent in HIV-1-infected patients.IMPORTANCE HIV-1 persistence in a small pool of long-lived latently infected resting CD4+ T cells is a major barrier to viral eradication in HIV-1-infected patients on antiretroviral therapy. A potential strategy to cure HIV-1-infection is the use of latency-reversing agents to eliminate the reservoirs established in resting CD4+ T cells. As no drug has been shown to be completely effective so far, the search for new drugs and combinations remains a priority for HIV cure. We examined the ability of maraviroc, a CCR5 antagonist used as an antiretroviral drug, to activate latent HIV-1 in infected individuals on antiretroviral therapy. The study showed that maraviroc can activate NF-κB and, subsequently, induce latent HIV-1-transcription in resting CD4+ T cells from HIV-1-infected individuals on suppressive antiretroviral therapy. Additional interventions will be needed to eliminate latent HIV-1 infection. Our results suggest that maraviroc may be a new latency-reversing agent to interfere with HIV-1 persistence during antiretroviral therapy.