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Defective thymic output in WAS patients is associated with abnormal actin organization.

ABSTRACT: Wiskott-Aldrich syndrome protein (WASp) is a key regulator of the actin cytoskeleton. Defective T - cell function is a major cause for immune deficiency in Wiskott-Aldrich syndrome (WAS) patients. T cells originate in the bone marrow and develop in the thymus, and then migrate to peripheral tissues. TCR excision circles (TRECs) present in thymic output cells stably, which is used as a molecular marker for thymic output. We found that CD8+ T naïve cells of classic WAS patients were significantly reduced, and TRECs in patients with classic WAS and X-linked thrombocytopenia (XLT) dramatically decreased compared with that of HCs. TRECs were also reduced in WAS (KO) mice. These suggest that defective thymic output partially accounts for T cell lymphopenia in WAS patients. However, the correlation between the defect of thymic output and actin organization still remains elusive. We found that the subcellular location and the levels of of F-actin were altered in T cells from both WAS and XLT patients compared to that of HCs with or without stimulation. Our study shows that WASp plays a critical role in thymic output, which highly correlates with the subcellular location and level of F-actin in T cells.

SUBMITTER: Li W

PROVIDER: S-EPMC5607224 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Defective thymic output in WAS patients is associated with abnormal actin organization.

Li Wenyan W Sun Xiaoyu X Wang Jinzhi J Zhao Qin Q Dai Rongxin R Wang Yanping Y Zhou Lina L Westerberg Lisa L Ding Yuan Y Zhao Xiaodong X Liu Chaohong C

Scientific reports 20170920 1

Wiskott-Aldrich syndrome protein (WASp) is a key regulator of the actin cytoskeleton. Defective T - cell function is a major cause for immune deficiency in Wiskott-Aldrich syndrome (WAS) patients. T cells originate in the bone marrow and develop in the thymus, and then migrate to peripheral tissues. TCR excision circles (TRECs) present in thymic output cells stably, which is used as a molecular marker for thymic output. We found that CD8<sup>+</sup> T naïve cells of classic WAS patients were sig ...[more]

PMID: 28931895

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Project description:BackgroundChronic kidney disease (CKD) is age-related disease, and decreased renal function is associated with the premature aging of T cells and increased incidence of other age-related diseases. However, the relationship between T cell senescence and CKD progression remains unclear. Here, we investigated the relationship between T cell senescence, as indicated by decreased thymic output and increased proportion of highly differentiated CD28- T cells, and CKD progression.ResultsA total of 175 patients with non-dialysis-dependent CKD were enrolled in this study. Thymic output was assessed based on the CD45RA+CD31+CD4+ cell (recent thymic emigrant [RTE]) counts (RTEs) (/mm3) and the proportion of RTE among CD4+ T cells (RTE%). Highly differentiated T cells were assessed based on the proportion of CD28- cells among CD4+ T cells (CD28-/CD4+) and CD28- cells among CD8+ T cells (CD28-/CD8+). The primary outcome was estimated glomerular filtration rate (eGFR) decline of ≥40% or initiation of renal replacement therapy. The association between T cell senescence and renal outcomes was examined using Cox proportional hazards models and restricted cubic splines. The median age was 73 years, 33% were women, and the median eGFR was 26 mL/min/1.73 m2. The median RTEs, RTE%, CD28-/CD4+, and CD28-/CD8+ were 97.5/mm3, 16.2, 5.3, and 49.7%, respectively. After a median follow-up of 1.78 years, renal outcomes were observed in 71 patients. After adjusting for age, sex, eGFR, proteinuria, diabetes, and cytomegalovirus seropositivity, decreased RTEs, which corresponded to decreased thymic output, significantly and monotonically increased the risk of poor renal outcome (p = 0.04), and decreased RTE% and increased highly differentiated CD28-/CD4+ T cells also tended to monotonically increase the risk (p = 0.074 and p = 0.056, respectively), but not CD28-/CD8+ T cells.ConclusionsDecreased thymic output in CKD patients, as well as increased highly differentiated CD4+ T cells, predicted renal outcomes. Thus, the identification of patients prone to CKD progression using T cell senescence, particularly decreased RTE as a biomarker, may help to prevent progression to end-stage kidney disease.

Project description:Background: Visceral leishmaniasis/HIV-co-infected patients (VL/HIV) accounts for around 8% of VL reported cases in Brazil. Relapses of Leishmania infection after anti-leishmanial treatment constitute a great challenge in the clinical practice because of the disease severity and drug resistance. We have shown that non-relapsing-VL/HIV (NR-) evolved with increase of CD4+ T-cell counts and reduction of activated CD4+ and CD8+ T cells after anti-leishmanial treatment. This immune profile was not observed in relapsing-VL/HIV patients (R-), indicating a more severe immunological compromising degree. Elevated activation status may be related to a deficient immune reconstitution and could help to explain the frequent relapses in VL/HIV co-infection. Our aim was to evaluate if this gain of T cells was related to changes in the peripheral TCRV? repertoire and inflammatory status, as well as the possible thymus involvement in the replenishment of these newly formed T lymphocytes. Methods: VL/HIV patients, grouped into non-relapsing (NR- = 6) and relapsing (R- = 12) were evaluated from the active phase up to 12 months post-treatment (mpt). HIV-infected patients (non-VL) and healthy subjects (HS) were included. The TCRV? repertoire was evaluated ex vivo by flow cytometry, whereas the plasmatic cytokine levels were assessed by Luminex assay. To evaluate the thymic output, DNA was extracted from PBMCs for TCR rearrangement excision circles (TREC) quantification by qPCR. Results: VL/HIV cases presented an altered mobilization profile (expansions or retractions) of the TCRV? families when compared to HS independent of the follow-up phase (p < 0.05). TCRV? repertoire on CD4+ T-cells was more homogeneous in the NR-VL/HIV cases, but heterogeneous on CD8+ T-cells, since different V?-families were mobilized. NR-VL/HIV had the inflammatory pattern reduced after 6 mpt. Importantly, VL/HIV patients showed number of TREC copies lower than controls during all follow-up. An increase of recent thymic emigrants was observed in NR-VL/HIV individuals at 10 mpt compared to R- patients (p < 0.01), who maintained lower TREC contents than the HIV controls. Conclusions: VL/HIV patients that maintain the thymic function, thus generating new T-cells, seem able to replenish the T lymphocyte compartment with effector cells, then enabling parasite control.

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Defective thymic output in WAS patients is associated with abnormal actin organization.

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Defective thymic output in WAS patients is associated with abnormal actin organization.

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