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CD8+ T-cell senescence and skewed lymphocyte subsets in young Dyskeratosis Congenita patients with PARN and DKC1 mutations.

ABSTRACT: BACKGROUND:Dyskeratosis congenita (DC) is a syndrome resulting from defective telomere maintenance. Immunodeficiency associated with DC can cause significant morbidity and lead to premature mortality, but the immunological characteristics and molecular hallmark of DC patients, especially young patients, have not been described in detail. METHODS:We summarize the clinical data of two juvenile patients with DC. Gene mutations were identified by whole-exome and direct sequencing. Swiss-PdbViewer was used to predict the pathogenicity of identified mutations. The relative telomere length was determined by QPCR, and a comprehensive analysis of lymphocyte subsets and CD57 expression was performed by flow cytometry. RESULTS:Both patients showed typical features of DC without severe infection. In addition, patient 1 (P1) was diagnosed with Hoyeraal-Hreidarsson syndrome due to cerebellar hypoplasia. Gene sequencing showed P1 had a compound heterozygous mutation (c.204G > T and c.178-245del) in PARN and P2 had a novel hemizygous mutation in DKC1 (c.1051A > G). Lymphocyte subset analysis showed B and NK cytopenia, an inverted CD4:CD8 ratio, and decreased naïve CD4 and CD8 cells. A significant increase in CD21low B cells and skewed numbers of helper T cells (Th), regulatory T cells (Treg), follicular regulatory T cells (Tfr), and follicular helper T cells (Tfh) were also detected. Short telomere lengths, increased CD57 expression, and an expansion of CD8 effector memory T cells re-expressing CD45RA (TEMRA) were also found in both patients. CONCLUSION:Unique immunologic abnormalities, CD8 T-cell senescence, and shortened telomere together as a hallmark occur in young DC patients before progression to severe disease.

SUBMITTER: Zeng T

PROVIDER: S-EPMC7521304 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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CD8<sup>+</sup> T-cell senescence and skewed lymphocyte subsets in young Dyskeratosis Congenita patients with PARN and DKC1 mutations.

Zeng Ting T Lv Ge G Chen Xuemei X Yang Lu L Zhou Lina L Dou Ying Y Tang Xuemei X Yang Jun J An Yunfei Y Zhao Xiaodong X

Journal of clinical laboratory analysis 20200525 9

<h4>Background</h4>Dyskeratosis congenita (DC) is a syndrome resulting from defective telomere maintenance. Immunodeficiency associated with DC can cause significant morbidity and lead to premature mortality, but the immunological characteristics and molecular hallmark of DC patients, especially young patients, have not been described in detail.<h4>Methods</h4>We summarize the clinical data of two juvenile patients with DC. Gene mutations were identified by whole-exome and direct sequencing. Swi ...[more]

PMID: 32452087

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Project description:Aging is the consequence of intra- and extracellular events that promote cellular senescence. Dyskeratosis congenita (DC) is an example of a premature aging disorder caused by underlying telomere/telomerase-related mutations. Cells from these patients offer an opportunity to study telomere-related aging and senescence. Our previous work has found that telomere shortening stimulates DNA damage responses (DDR) and increases reactive oxygen species (ROS), thereby promoting entry into senescence. This work also found that telomere elongation via TERT expression, the catalytic component of the telomere-elongating enzyme telomerase, or p53 shRNA could decrease ROS by disrupting this telomere-DDR-ROS pathway. To further characterize this pathway, we performed a CRISPR/Cas9 knockout screen to identify genes that extend lifespan in DC cells. Of the cellular clones isolated due to increased lifespan, 34% had a guide RNA (gRNA) targeting CEBPB while gRNAs targeting WSB1, MED28 and p73 were observed multiple times. CEBPB is a transcription factor associated with activation of proinflammatory response genes suggesting that inflammation may be present in DC cells. The inflammatory response was investigated using RNA-Seq to compare DC and control cells. Expression of inflammatory genes were found to be significantly elevated (p<0.0001) in addition to a key subset of these inflammation-related genes (IL1B, IL6, IL8, IL12A, CXCL1 (GROa), CXCL2 (GROb), and CXCL5) which are regulated by CEBPB. Exogenous TERT expression led to downregulation of RNA/protein CEBPB expression and the inflammatory response genes suggesting a telomere-length dependent mechanism to regulate CEBPB. Furthermore, unlike exogenous TERT and p53 shRNA, CEBPB shRNA did not significantly decrease ROS suggesting that CEBPB’s contribution in DC cells’ senescence is ROS-independent. Our findings demonstrate a key role for CEBPB in engaging senescence by mobilizing an inflammatory response within DC cells.

Dataset Information

CD8+ T-cell senescence and skewed lymphocyte subsets in young Dyskeratosis Congenita patients with PARN and DKC1 mutations.

Publications

CD8<sup>+</sup> T-cell senescence and skewed lymphocyte subsets in young Dyskeratosis Congenita patients with PARN and DKC1 mutations.

Similar Datasets

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