Increased Frequency of Memory CD4+ T-Cell Responses in Individuals With Previously Treated Extrapulmonary Tuberculosis.

Extrapulmonary TB (EPTB) occurs with increased frequency in persons with underlying immunodeficiency. Even after recovery from acute illness, differences in immune phenotype and activation persist. Studies defining characteristics of immune responses after recovery from extrapulmonary TB may provide insights into factors that increase TB risk. We performed two case-control studies (in the United States and Brazil) among HIV-seronegative adults with previous EPTB (n = 9; 25), previous pulmonary TB (n = 7; 25), latent M. tuberculosis (Mtb) infection (n = 11; 25), and uninfected TB contacts (n = 10; 25). We assessed the frequency of dual CD4+ interferon-γ and tumor necrosis factor-α responses after stimulation with overlapping Mtb peptides from ESAT-6 or CFP-10, or gamma-irradiated Mtb H37Rv, proliferative responses to Mtb antigens, T-regulatory cell (Treg) frequency and phenotype. In both study populations, individuals with prior EPTB had the highest frequency of intracellular cytokine-producing cells in response to Mtb antigens (p < 0.05; p <.0001). Persons with prior EPTB in Brazil had the highest levels of CD4 proliferation to Mtb antigens (p < 0.0001), and the highest expression of CD39 on Tregs (p < 0.0001). Individuals with treated EPTB maintained high frequencies of Mtb-specific memory responses and active Treg cells, suggesting that susceptibility to EPTB occurs despite the ability to develop and maintain enhanced adaptive immune responses.

Kawasaki Disease Substantially Impacts Health-Related Quality of Life.

OBJECTIVE: To prospectively evaluate the acute impact of Kawasaki disease (KD) on health-related quality of life (HRQoL) and to assess deterioration in the HRQoL experienced by children with KD compared with other childhood diseases. STUDY DESIGN: We merged the Outcomes Assessment Program database obtained prospectively with the existing KD database and queried for KD admissions between 1 month and 13 years of age. HRQoL was evaluated with the parent-proxy Pediatric Quality of Life Inventory (PedsQL) 4.0 Generic Core and Infant Scales. We compared the KD HRQoL results with those obtained from newly diagnosed patients with cancer and pneumonia, matched for age, sex and race. PedsQL total scores over time were assessed with ANCOVA models, adjusted for matching variables and PedsQL score prior to admission. RESULTS: We identified 89 patients with KD and compared 65 subjects with an equal number with pneumonia and with 67 subjects with newly diagnosed cancer. Patients with demonstrated lower PedsQL total score on admission and suffered a significantly greater HRQoL decline from baseline to admission than the other groups. KD diagnostic subtype (complete or incomplete) and coronary artery dilatation were not associated with HRQoL outcomes. However, non-intravenous immunoglobulin responders showed greater HRQoL decline than responders (P = .03). CONCLUSIONS: Children with KD suffer acute and significant HRQoL impairment exceeding that of children newly diagnosed with cancer. Lack of immediate treatment response may exert an additional HRQoL burden, whereas KD subtype and coronary artery dilatation do not.

Chronic HIV-1 Infection Impairs Superantigen-Induced Activation of Peripheral CD4+CXCR5+PD-1+ Cells, With Relative Preservation of Recall Antigen-Specific Responses.

Peripheral CD4+CXCR5+PD-1+ T cells are a putative circulating counterpart to germinal center T follicular helper (TFH) cells. They show both phenotypic and functional similarities to TFH cells, which provide necessary help for the differentiation of B cells to antibody-secreting plasmablasts. In this study, we evaluated the frequency, phenotypes, and responses of peripheral TFH-like (pTFH) cells to superantigen and recall antigen stimulation in 10 healthy and 34 chronically infected treatment-naive HIV-1+ individuals. There was no difference in the frequency of pTFH cells between HIV+ and HIV- individuals. Surface expression of ICOS, but not CD40L, was higher on pTFH cells at baseline in HIV+ individuals. Compared with HIV- individuals, pTFH cells from HIV+ individuals had decreased maximal expression of ICOS and CD40L in response to in vitro superantigen stimulation. This decreased response did not correlate with viral control, CD4 T-cell count, duration of infection, or the degree of neutralizing antibody breadth. Despite a decreased maximal response, pTFH responses to HIV Gag and tetanus toxoid recall antigens were preserved.

Antiretroviral therapy reduces the magnitude and T cell receptor repertoire diversity of HIV-specific T cell responses without changing T cell clonotype dominance.

After initiation of antiretroviral therapy (ART), HIV loads and frequencies of HIV epitope-specific immune responses decrease. A diverse virus-specific T cell receptor (TCR) repertoire allows the host to respond to viral epitope diversity, but the effect of antigen reduction as a result of ART on the TCR repertoire of epitope-specific CD8(+) T cell populations has not been well defined. We determined the TCR repertoires of 14 HIV-specific CD8(+) T cell responses from 8 HIV-positive individuals before and after initiation of ART. We used multiparameter flow cytometry to measure the distribution of memory T cell subsets and the surface expression of PD-1 on T cell populations and T cell clonotypes within epitope-specific responses from these individuals. Post-ART, we noted decreases in the frequency of circulating epitope-specific T cells (P = 0.02), decreases in the number of T-cell clonotypes found within epitope-specific T cell receptor repertoires (P = 0.024), and an overall reduction in the amino acid diversity within these responses (P < 0.0001). Despite this narrowing of the T cell response to HIV, the overall hierarchy of dominant T cell receptor clonotypes remained stable compared to that pre-ART. CD8(+) T cells underwent redistributions in memory phenotypes and a reduction in CD38 and PD-1 expression post-ART. Despite extensive remodeling at the structural and phenotypic levels, PD-1 was expressed at higher levels on dominant clonotypes within epitope-specific responses before and after initiation of ART. These data suggest that the antigen burden may maintain TCR diversity and that dominant clonotypes are sensitive to antigen even after dramatic reductions after initiation of ART.

Identification of calcium-modulating cyclophilin ligand as a human host restriction to HIV-1 release overcome by Vpu.

The HIV-1 Vpu protein is required for efficient viral release from human cells. For HIV-2, the envelope (Env) protein replaces the role of Vpu. Both Vpu and HIV-2 Env enhance virus release by counteracting an innate host-cell block within human cells that is absent in African green monkey (AGM) cells. Here we identify calcium-modulating cyclophilin ligand (CAML) as a Vpu-interacting host factor that restricts HIV-1 release. Expression of human CAML (encoded by CAMLG) in AGM cells conferred a strong restriction of virus release that was reversed by Vpu and HIV-2 Env, suggesting that CAML is the mechanistic link between these two viral regulators. Depletion of CAML in human cells eliminated the need for Vpu in enhancing HIV-1 and murine leukemia virus release. These results point to CAML as a Vpu-sensitive host restriction factor that inhibits HIV release from human cells. The ability of CAML to inhibit virus release should illuminate new therapeutic strategies against HIV.

The pericentriolar recycling endosome plays a key role in Vpu-mediated enhancement of HIV-1 particle release.

The HIV-1 accessory gene product Vpu is required for efficient viral particle release from infected human cells. The mechanism by which Vpu enhances particle assembly or release is not yet defined. Here, we identify an intracellular site that is critical for Vpu-mediated enhancement of particle release. Vpu was found to co-localize with markers for the pericentriolar recycling endosome. Expression of dominant negative mutants of Rab11a and myosin Vb that disrupt protein sorting through the recycling endosome abrogated the ability of Vpu to augment particle release. Remarkably, the effects of blocking recycling endosome function on HIV particle release were demonstrable only in human cell lines known to be responsive to Vpu, while no effect on particle release was seen in African green monkey cells. Inhibition of recycling endosome function in human cells also blocked the ability of HIV-2 envelope to enhance particle release. These studies indicate that Vpu and HIV-2 envelope glycoprotein enhance particle release via a common mechanism that requires the activity of the pericentriolar recycling endosome.

Viral protein U counteracts a human host cell restriction that inhibits HIV-1 particle production.

Human cells resist viral infections by a variety of mechanisms. Viruses must overcome host cell restrictions to successfully reproduce their genetic material. Here, we identify a host restriction to viral replication that acts at the stage of particle assembly. Viral protein U (Vpu) is an HIV-1 accessory protein that enhances particle assembly and release in most human cells, but not in simian cells. By using human-simian cell heterokaryons, we show that the inhibition of assembly in human cells is dominant. Vpu overcomes the block to assembly in human cells and in human-simian heterokaryons. The HIV-1 vpu gene may have evolved to counteract an assembly restriction that is present in human cells.

Human immunodeficiency virus type-1 activates lytic cycle replication of Kaposi's sarcoma-associated herpesvirus through induction of KSHV Rta.

Human immunodeficiency virus type-1 (HIV-1) infection dramatically increases the risk of development of Kaposi's sarcoma (KS) in individuals infected with Kaposi's sarcoma-associated herpesvirus (KSHV). In a primary effusion lymphoma (PEL) tissue culture model system, HIV-1 replication potently induced the lytic replication of KSHV and led to the secretion of soluble factors capable of inducing lytic KSHV replication in bystander cells. Here we demonstrate that HIV induces KSHV lytic replication through activation of the KSHV Rta. HIV gene expression activated the KSHV Rta promoter following viral infection or after transfection of proviral DNA. Although HIV-1 Tat has previously been implicated as an activator of KSHV lytic replication, Tat alone was unable to activate lytic replication and failed to activate the Rta promoter. We conclude that HIV activates KSHV lytic replication by inducing the KSHV Rta promoter and that factors other than HIV-1 Tat are required to mediate this effect.