Truncated stathmin-2 is a marker of TDP-43 pathology in frontotemporal dementia.

No treatment for frontotemporal dementia (FTD), the second most common type of early-onset dementia, is available, but therapeutics are being investigated to target the 2 main proteins associated with FTD pathological subtypes: TDP-43 (FTLD-TDP) and tau (FTLD-tau). Testing potential therapies in clinical trials is hampered by our inability to distinguish between patients with FTLD-TDP and FTLD-tau. Therefore, we evaluated truncated stathmin-2 (STMN2) as a proxy of TDP-43 pathology, given the reports that TDP-43 dysfunction causes truncated STMN2 accumulation. Truncated STMN2 accumulated in human induced pluripotent stem cell-derived neurons depleted of TDP-43, but not in those with pathogenic TARDBP mutations in the absence of TDP-43 aggregation or loss of nuclear protein. In RNA-Seq analyses of human brain samples from the NYGC ALS cohort, truncated STMN2 RNA was confined to tissues and disease subtypes marked by TDP-43 inclusions. Last, we validated that truncated STMN2 RNA was elevated in the frontal cortex of a cohort of patients with FTLD-TDP but not in controls or patients with progressive supranuclear palsy, a type of FTLD-tau. Further, in patients with FTLD-TDP, we observed significant associations of truncated STMN2 RNA with phosphorylated TDP-43 levels and an earlier age of disease onset. Overall, our data uncovered truncated STMN2 as a marker for TDP-43 dysfunction in FTD.

Altered cord blood gammadelta T cell repertoire in Nigeria: possible impacts of environmental factors on neonatal immunity.

Infectious diseases during pregnancy can impact the development of fetal immunity, leading to reduced neonatal resistance to infection and decreased responses to pediatric vaccines. Plasmodium falciparum causes placental infection in low parity pregnant women and is among the pathogens that affect fetal immunity. Recognizing the relationship between malaria and gammadelta T lymphocytes in adults, we asked whether neonatal gammadelta T cells would be altered in malaria-endemic regions as a marker for changes in fetal immunity. Our initial studies compared cord blood gammadelta T cells from deliveries to HIV- mothers in Jos (Nigeria) where malaria is endemic, or in Rome (Italy). We noted substantial differences in the Vgamma2 repertoire for cord blood collected in Jos or Rome; differences were consistent with a negative selection mechanism operating on the fetal Vgamma2 chain repertoire in neonates from Jos. A specific disruption affected the fraction of gammadelta T cells that we expect will respond to Bacille Calmette-Guerin (BCG). Fetal gammadelta T cell depletion might be a mechanism for impaired neonatal immunity and lowered responses to pediatric vaccines.

Postmortem Cortex Samples Identify Distinct Molecular Subtypes of ALS: Retrotransposon Activation, Oxidative Stress, and Activated Glia.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. While several pathogenic mutations have been identified, the vast majority of ALS cases have no family history of disease. Thus, for most ALS cases, the disease may be a product of multiple pathways contributing to varying degrees in each patient. Using machine learning algorithms, we stratify the transcriptomes of 148 ALS postmortem cortex samples into three distinct molecular subtypes. The largest cluster, identified in 61% of patient samples, displays hallmarks of oxidative and proteotoxic stress. Another 19% of the samples shows predominant signatures of glial activation. Finally, a third group (20%) exhibits high levels of retrotransposon expression and signatures of TARDBP/TDP-43 dysfunction. We further demonstrate that TDP-43 (1) directly binds a subset of retrotransposon transcripts and contributes to their silencing in vitro, and (2) pathological TDP-43 aggregation correlates with retrotransposon de-silencing in vivo.

Failure to restore the Vgamma2-Jgamma1.2 repertoire in HIV-infected men receiving highly active antiretroviral therapy (HAART).

Gammadelta (gammadelta) T cells expressing the Vgamma2-Jgamma1.2Vdelta2 (Vgamma9-JPVdelta2, alternate nomenclature) T cell receptor (TCR) constitute the major peripheral blood population of gammadelta T cells in adult humans and are specifically depleted during human immunodeficiency virus (HIV) disease. Vgamma2-Jgamma1.2Vdelta2 T cells provide a convenient model for assessing the impact of antiretroviral therapy on cell populations that are not susceptible to direct infection because they do not express CD4 and depletion occurs by indirect mechanisms. We obtained longitudinal PBMC samples from 16 HIV-infected individuals who enrolled in the Multicenter AIDS Cohort Study (MACS) and were starting highly active antiretroviral therapy (HAART). Vgamma2-Jgamma1.2Vdelta2 T cells were depleted in these individuals as a result of HIV infection. Despite evidence for clinical benefits of HAART, the Vgamma2-Jgamma1.2Vdelta2 T cell repertoire did not recover after HAART initiation irrespective of treatment duration. These studies highlight important defects among cell subsets lost due to indirect effects of HIV.

Innate-like gammadelta T cell responses to mycobacterium Bacille Calmette-Guerin using the public V gamma 2 repertoire in Macaca fascicularis.

The V gamma 2 V delta 2 T cell subset responds to Bacille Calmette-Guerin (BCG) immunization in macaques and may be a component of protective immunity against tuberculosis. We characterized the effects of BCG on the V gamma 2 V delta 2 T cell receptor repertoire by comparing the starting population of V gamma 2 chains in cynomolgus macaques with the repertoire found after priming or booster immunization with BCG. The starting repertoire was dominated by public V gamma 2 chain sequences that were found repeatedly among unrelated animals. Primary exposure to BCG triggered expansion of cells expressing public V gamma 2 chains and booster immunization was often associated with contraction of these same subsets. Thus, BCG-reactive V gamma 2 chains were present at high frequency in the repertoire of mycobacteria-naïve macaques and they comprised the major response to primary or booster immunization. Normal selection processes that created the naïve V gamma 2 repertoire in macaques, also encoded the capacity for rapid responses to mycobacteria. The unusual composition of a normal V gamma 2 repertoire helps to explain the powerful gammadelta T cell responses to BCG immunization.

HIV-mediated gammadelta T cell depletion is specific for Vgamma2+ cells expressing the Jgamma1.2 segment.

Circulating Vgamma2/Vdelta2(+) T cells, normally constituting 3-6% of all CD3(+) T cells in blood, are severely depleted after HIV infection. The mechanism(s) for Vgamma2/Vdelta2(+) T cell depletion are unknown, partly because these cells are CD4(-) and resistant to HIV infection. To determine whether this cell depletion was general for all Vgamma2(+) cells or specific for an individual subset, we analyzed the Vgamma2 repertoire and found consistent differences between HIV(+) and uninfected control samples. The change in Vgamma2 repertoire was the result of preferentially depleting only those Vgamma2 cells that express the Jgamma1.2 segment. The specific loss of Vgamma2-Jgamma1.2(+) cells was polyclonal, as the Vgamma subset retained normal diversity even after HIV infection, and loss occurred without significant changes in the paired chain (Vdelta2) repertoire, or in the alternate Vdelta1 chain repertoire. Specific depletion of Vgamma2-Jgamma1.2/Vdelta2 T cells is the first evidence of a common, T cell receptor-dependent cell loss in HIV disease and it provides a clear example of bystander cell depletion. Vgamma2-Jgamma1.2/Vdelta2 T cells mediate potent responses to microbial pathogens including HIV, and loss of this subset is an important aspect of AIDS pathogenesis.

Vaccinia virus inhibits T cell receptor-dependent responses by human gammadelta T cells.

Vaccinia virus (VV) is an effective vaccine and vector but has evolved multiple mechanisms for evading host immunity. We characterized the interactions of VV (TianTan and New York City Board of Health strains) with human gammadelta T cells because of the role they play in immune control of this virus. Exposure to VV failed to trigger proliferative responses in gammadelta T cells from unprimed individuals, but it was an unexpected finding that VV blocked responses to model antigens by the Vgamma2Vdelta2 T cell subset. Infectious or ultraviolet light-inactivated VV inhibited proliferative Vgamma2Vdelta2 T cell responses to phosphoantigens and tumor cells, prevented cytolysis of Daudi B cells, and reduced cytokine production. Inhibiting Vgamma2Vdelta2 T cells may be a mechanism for evading host immunity and increasing VV virulence. Increased VV replication or expression in the absence of gammadelta T cell responses might contribute to its potency as a vaccine against poxvirus and recombinant antigens.

Gamma interferon secretion by human Vgamma2Vdelta2 T cells after stimulation with antibody against the T-cell receptor plus the Toll-Like receptor 2 agonist Pam3Cys.

Circulating Vgamma2Vdelta2 T-cell populations in healthy human beings are poised for rapid responses to bacterial or viral pathogens. We asked whether Vgamma2Vdelta2 T cells use the Toll-like receptor (TLR) family to recognize pathogen-associated molecular pattern molecules and to regulate cell functions. Analysis of expanded Vgamma2Vdelta2 T-cell lines showed the abundant presence of TLR2 mRNA, implying that these receptors are important for cell differentiation or function. However, multiple efforts to detect TLR2 protein on the cell surface or in cytoplasmic compartments gave inconsistent results. Functional assays confirmed that human Vgamma2Vdelta2 T cells could respond to the TLR2 agonist (S)-(2,3-bis(palmitoyloxy)-(2RS)-propyl)-N-palmitoyl-(R)-Cys-(S)-Ser(S)-Lys4-OH trihydrochloride (Pam3Cys), but the response required coincident stimulation through the gammadelta T-cell receptor (TCR). Dually stimulated cells produced higher levels of cytoplasmic or cell-free gamma interferon and showed increased expression of the lysosome-associated membrane protein CD107a on the cell surface. A functional TLR2 that requires coincident TCR stimulation may increase the initial potency of Vgamma2Vdelta2 T-cell responses at the site of infection and promote the rapid development of subsequent acquired antipathogen immunity.

The Vgamma2/Vdelta2 T-cell repertoire in Macaca fascicularis: functional responses to phosphoantigen stimulation by the Vgamma2/Jgamma1.2 subset.

Circulating Vgamma2/Vdelta2 T cells in human and non-human primates respond to small molecular weight non-peptidic phosphoantigens in a major histocompatibility complex (MHC)-unrestricted manner. These responses are encoded by the Vgamma2/Jgamma1.2 chain of the T-cell receptor and are positively selected during early development to create a biased repertoire in adults. We characterized the Vgamma2 chain in cynomolgus macaques (Macaca fascicularis) to develop a non-human primate model for studying the effects of infection and therapy on the circulating Vgamma2/Vdelta2 T-cell subset. The cynomolgus macaque Vgamma2 chain was highly homologous to the Vgamma2 chain from human beings and rhesus macaques (Macaca mulatta), though we noted conserved substitutions in critical residues within the CDR3 for both macaque species. Despite these substitutions, Vgamma2/Vdelta2+ T cells from cynomolgus monkeys exhibited polyclonal responses to two different phosphoantigens. Proliferative responses were observed with both isopentenylpyrophosphate and alendronate, but stronger interferon-gamma secretory responses were observed with isopentenylpyrophosphate. In vitro stimulation and expansion led to selective outgrowth of the Vgamma2/Jgamma1.2 subset, with a marked shift in the Vgamma2 spectratype. As a result of the less biased starting repertoire for Vgamma2, the cynomolgus macaque constitutes a sensitive model for examining the effects of in vitro or in vivo treatments on the Vgamma2/Vdelta2 T-cell population. Our studies establish the value of cynomolgus macaques as a model for Vgamma2/Vdelta2 T-cell responses to non-peptidic antigens, and further evidence the remarkable evolutionary conservation of this unusual, phosphoantigen-responsive T-cell subset that is found only in primate species.

Association between longer duration of HIV-suppressive therapy and partial recovery of the V gamma 2 T cell receptor repertoire.

Human immunodeficiency virus (HIV) infection alters the function and repertoire of peripheral blood gamma delta T cells expressing the V gamma 2/V delta 2 T cell receptor (TCR). A cross-sectional comparison of the V gamma 2 TCR repertoire was performed for 56 HIV-infected subjects, 51 of whom were receiving highly active antiretroviral therapy (HAART), to measure changes in the V gamma 2 TCR repertoire. Longer durations of HAART were associated with partial recovery of the normal TCR repertoire, and recovery was greatest in subjects with complete virus suppression. Changes in the V gamma 2 TCR repertoire are sensitive measures for the effects of HAART and of residual HIV replication.