Mucosal-associated invariant T (MAIT) cells are an evolutionarily conserved antimicrobial MR1-restricted T-cell subset. MAIT cells are CD161+, express a Vα7.2 TCR, are primarily CD8+ and numerous in ...blood and mucosal tissues. However, their role in HIV-1 infection is unknown. In this study, we found levels of MAIT cells to be severely reduced in circulation in patients with chronic HIV-1 infection. Residual MAIT cells were highly activated and functionally exhausted. Their decline was associated with time since diagnosis, activation levels, and the concomitant expansion of a subset of functionally impaired CD161− Vα7.2+ T cells. Such cells were generated in vitro by exposure of MAIT cells to Escherichia coli. Notably, whereas the function of residual MAIT cells was at least partly restored by effective antiretroviral therapy, levels of MAIT cells in peripheral blood were not restored. Interestingly, MAIT cells in rectal mucosa were relatively preserved, although some of the changes seen in blood were recapitulated in the mucosa. These findings are consistent with a model in which the MAIT-cell compartment, possibly as a result of persistent exposure to microbial material, is engaged, activated, exhausted, and progressively and persistently depleted during chronic HIV-1 infection.
•Antimicrobial CD8+ MAIT cells are activated, exhausted, and progressively and persistently depleted during chronic HIV-1 infection.•This decline in MAIT cell level and function may seriously impair the ability to mount immune responses to bacterial and fungal pathogens.
FK506 binding proteins (FKBPs), also called immunophilins, are prolyl-isomerases (PPIases) that participate in a wide variety of cellular functions including hormone signaling and protein folding. ...Recent studies indicate that proteins that contain PPIase activity can also alter the processing of Alzheimer's Amyloid Precursor Protein (APP). Originally identified in hematopoietic cells, FKBP52 is much more abundantly expressed in neurons, including the hippocampus, frontal cortex, and basal ganglia. Given the fact that the high molecular weight immunophilin FKBP52 is highly expressed in CNS regions susceptible to Alzheimer's, we investigated its role in Aβ toxicity. Towards this goal, we generated Aβ transgenic Drosophila that harbor gain of function or loss of function mutations of FKBP52. FKBP52 overexpression reduced the toxicity of Aβ and increased lifespan in Aβ flies, whereas loss of function of FKBP52 exacerbated these Aβ phenotypes. Interestingly, the Aβ pathology was enhanced by mutations in the copper transporters Atox1, which interacts with FKBP52, and Ctr1A and was suppressed in FKBP52 mutant flies raised on a copper chelator diet. Using mammalian cultures, we show that FKBP52 (−/−) cells have increased intracellular copper and higher levels of Aβ. This effect is reversed by reconstitution of FKBP52. Finally, we also found that FKBP52 formed stable complexes with APP through its FK506 interacting domain. Taken together, these studies identify a novel role for FKBP52 in modulating toxicity of Aβ peptides.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Tissue-resident memory (T
) CD8
T-cells are non-recirculating, long-lived cells housed in tissues that can confer protection against mucosal pathogens. Human immunodeficiency virus-1 (HIV-1) is a ...mucosal pathogen and the gastrointestinal tract is an important site of viral pathogenesis and transmission. Thus, CD8
T
cells may be an important effector subset for controlling HIV-1 in mucosal tissues. This study sought to determine the abundance, phenotype, and functionality of CD8
T
cells in the context of chronic HIV-1 infection. We found that the majority of rectosigmoid CD8
T-cells were CD69
CD103
S1PR1
and T-bet
Eomesodermin
, indicative of a tissue-residency phenotype similar to that described in murine models. HIV-1-specific CD8
T
responses appeared strongest in individuals naturally controlling HIV-1 infection. Two CD8
T
subsets, distinguished by CD103 expression intensity, were identified. CD103
CD8
T
primarily displayed a transitional memory phenotype and contained HIV-1-specific cells and cells expressing high levels of Eomesodermin, whereas CD103
CD8
T
primarily displayed an effector memory phenotype and were Eomesodermin
. These findings suggest a large fraction of CD8
T-cells housed in the human rectosigmoid mucosa are tissue-resident and that T
contribute to the anti-HIV-1 immune response. Further exploration of CD8
T
will inform development of anti-HIV-1 immune-based therapies and vaccines targeted to the mucosa.
Abstract
The gastrointestinal tract (GIT) is an important site of HIV transmission and pathogenesis. Preventing or curing HIV infection will likely entail maintenance of protective anti-HIV immune ...responses in the GIT. Tissue resident memory T-cells (TRM) are long-lived, non-recirculating memory T-cells localized in tissues including the GIT. Positioned near sites of infection, TRM have protective efficacy against several pathogens. The precise role CD8+ TRM in HIV infection is not known. Blood and GIT CD8+ TRM cells from HIV+ and HIV- adults were identified by flow cytrometry using CD45RO, CD69, CD103, S1PR1, T-bet, and Eomesodermin (Eomes). Functionality was assessed in a 6-hour ex vivo stimulation assay. Cells were stimulated with DMSO, Gag, or Staphylococcal Enterotoxin B, and stained for CD107a, IFNγ, Mip-1β, TNFα, and IL-2. The frequency of CD103+CD69+S1PR1− CD8+ T-cells was significantly greater (P=0.005) in gut compared to blood (medians 54.8% and 0.10% respectively), indicative of tissue residency. CD45RO+ cells in this subset were classified as TRM. Consistent with murine studies, CD8+TRM were mainly T-betLowEomesNeg; however a population of EomesHigh CD8+ TRM emerged in HIV+ individuals not on antiretroviral therapy. Although polyfunctional Gag-specific CD8+ TRM responses (CD107a+, IFNγ+, Mip-1β+) appeared strongest in participants who control HIV without therapy (“controllers”), they constituted a smaller proportion of the total rectal Gag-specific CD8+ T-cell response compared to viremic participants not on ART (approximately 15% and 29% respectively). In summary, a large subset of CD8+ T-cells in rectal mucosa are TRM and likely play an important role in HIV-1 containment.
The central nervous system (CNS) is an important target of HIV, and cerebrospinal fluid (CSF) can provide a window into host-virus interactions within the CNS. The goal of this study was to determine ...whether HIV-specific CD8(+) T cells are present in CSF of HIV controllers (HC), who maintain low to undetectable plasma viremia without antiretroviral therapy (ART). CSF and blood were sampled from 11 HC, defined based on plasma viral load (VL) consistently below 2,000 copies/ml without ART. These included nine elite controllers (EC, plasma VL <40 copies/ml) and two viremic controllers (VC, VL 40-2,000 copies/ml). All controllers had CSF VL <40 copies/ml. Three comparison groups were also sampled: six HIV noncontrollers (NC, VL >10,000 copies/ml, no ART); seven individuals with viremia suppressed due to ART (Tx, VL <40 copies/ml); and nine HIV-negative controls. CD4(+) and CD8(+) T cells in CSF and blood were analyzed by flow cytometry to assess expression of CCR5, activation markers CD38 and HLA-DR, and memory/effector markers CD45RA and CCR7. HIV-specific CD8(+) T cells were quantified by major histocompatibility complex class I multimer staining. HIV-specific CD8(+) T cells were detected ex vivo at similar frequencies in CSF of HC and noncontrollers; the highest frequencies were in individuals with CD4 counts below 500 cells/μl. The majority of HIV-specific CD8(+) T cells in CSF were effector memory cells expressing CCR5. Detection of these cells in CSF suggests active surveillance of the CNS compartment by HIV-specific T cells, including in individuals with long-term control of HIV infection in the absence of therapy.
The gastrointestinal mucosa is an important site of HIV acquisition, viral replication, and pathogenesis. Immune cells in mucosal tissues frequently differ in phenotype and function from their ...non-mucosal counterparts. Although perforin-mediated cytotoxicity as measured in blood is a recognized correlate of HIV immune control, its role in gastrointestinal tissues is unknown. We sought to elucidate the cytotoxic features of rectal mucosal CD8+ T-cells in HIV infected and uninfected subjects. Perforin expression and lytic capacity were significantly reduced in rectal CD8+ T-cells compared with their blood counterparts, regardless of HIV clinical status; granzyme B (GrzB) was reduced to a lesser extent. Mucosal perforin and GrzB expression were higher in participants not on antiretroviral therapy compared with those on therapy and controls. Reduction in perforin and GrzB was not explained by differences in memory/effector subsets. Expression of T-bet and Eomesodermin was significantly lower in gut CD8+ T-cells compared with blood, and in vitro neutralization of TGF-β partially restored perforin expression in gut CD8+ T-cells. These findings suggest that rectal CD8+ T-cells are primarily non-cytotoxic, and phenotypically shaped by the tissue microenvironment. Further elucidation of rectal immune responses to HIV will inform the development of vaccines and immunotherapies targeted to mucosal tissues.
The Central Nervous system (CNS) is an important target of HIV-1 infection. Cerebrospinal fluid (CSF) sampling from HIV infected individuals can provide a window into host-virus interactions within ...the CNS. Cytotoxic CD8+ T-cells in the CNS can kill virally-infected target cells in an MHC Class I-restricted manner. HIV-specific CD8+ T cells present in the CNS/CSF could be involved in virus control, but alternatively could initiate pro-inflammatory processes in the CNS. One goal of the study was to understand the functions of cytotoxic CD8+ T cells in the CSF and the immunity mediated by them in chronic HIV infected individuals. This was done using tetrameric MHC Class I-peptide complexes, to directly stain antigen specific CD8+ T cells, and the frequency and characteristics of these cells was analyzed using flow cytometry. Another goal of this study was to explore the potential role of T cells in controlling CNS infection in chronic HIV infection, focusing on a rare subset of HIV-infected individuals known as "HIV Controllers". HIV-specific CD8+ T cells were detected in CSF of both HIV Controllers (HC) and Non-Controllers (NC). The CCR5+ HIV-specific CD8+ T cells in CSF of HC showed the highest median percentage compared to any other T cell population observed in HC in this study. The majority of CSF T cells in all patient groups were effector or central memory T cells. There was a difference in percentage of central memory CD8+ and CD4+ T cells in CSF between HC and NC suggesting that central memory T cells in CSF may play a primarily beneficial role in immune surveillance of the CNS. In both HC and NC, over 50% of HIV-specific CD8+ T cells in CSF and blood were effector memory cells. A relative lack of immune activation seen in the CSF of HC compared to NC suggests that both HIV replication and inflammation are relatively well controlled in the CSF of HC. Thus, Controllers are able to control HIV-1 infection in the CNS, possibly due to the presence of a strong antiviral immune surveillance mediated by memory T cells.
Antibiotics that have multiple cellular targets theoretically reduce the frequency of resistance evolution, but adaptive trajectories and resistance mechanisms against such antibiotics are ...understudied. Here we investigate these in methicillin resistant Staphylococcus aureus (MRSA) using experimental evolution upon exposure to delafloxacin (DLX), a novel fluoroquinolone that targets both DNA gyrase and topoisomerase IV. We show that selection for coding sequence mutations and genomic amplifications of the gene encoding a poorly characterized efflux pump, SdrM, leads to high DLX resistance, circumventing the requirement for mutations in both target enzymes. In the evolved populations, sdrM overexpression due to genomic amplifications containing sdrM and two adjacent genes encoding efflux pumps results in high DLX resistance, while the adjacent hitchhiking efflux pumps contribute to streptomycin cross-resistance. Further, lack of sdrM necessitates mutations in both target enzymes to evolve DLX resistance, and sdrM thus increases the frequency of resistance evolution. Finally, sdrM mutations and amplifications are similarly selected in two diverse clinical isolates, indicating the generality of this DLX resistance mechanism. Our study highlights that instead of reduced rates of resistance, evolution of resistance to multi-targeting antibiotics can involve alternate high-frequency evolutionary paths, that may cause unexpected alterations of the fitness landscape, including antibiotic cross-resistance.
Background: Mechanical neck pain (MNP) is one of the most prevalent musculoskeletal pathologies in the present time. Physiotherapy management strategies comprising manual therapy and exercise therapy ...are routinely administered in patients with MNP.
Objective: To compare the immediate effect of craniocervical flexion (CCF) exercise and Mulligan mobilisation on pain, active cervical range of motion (CROM) and CCF test performance in patients with MNP.
Methods: This prospective, randomised, single-blinded study involved 26 patients with MNP (16 females; mean age; Formula: see text years) randomised to a single session of active CCF exercise (3 sets of 10 repetitions) or Mulligan mobilisation (3 sets of 6–10 repetitions). Pain intensity was measured on a numerical pain rating scale (NPRS), active CROM was measured using CROM device, and CCF test performance with surface electromyography (EMG) from bilateral sternocleidomastoid (SCM) and anterior scalene (AS) muscles recorded pre- and immediately post-intervention by an assessor blinded to the treatment groups. Mann–Whitney U test was used to analyse between groups and Wilcoxon signed rank test was used to analyse within-group significance for pain and CROM, Cochran–Mantel–Haenszel correlation test was used to analyse the CCF test performance on EMG from the bilateral SCM and AS muscles.
Results: Comparison between pre- and post-intervention readings revealed statistically significant within-group (Formula: see text) and no between-group significant difference for pain, ROM, and CCF test performance, indicating both interventions were equally effective.
Conclusion: Patients with MNP who received active CCF exercise or Mulligan mobilisation exhibited similar reduction in pain intensity and increased CROM and CCF test performance post-intervention. Surprisingly, AS surface EMG amplitudes were increased post-intervention in both groups warranting further exploration of its role in neck pain.
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