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

Deciphering the impact of TERT/telomerase on immunosenescence and T cell revitalization

Immunosenescence impacts both the innate and adaptive immune systems, predominantly affecting certain immune cell types. A notable manifestation of immunosenescence is the diminished efficacy of adaptive immunity. The excessive senescence of immune cells, particularly T cells, leads to marked immune deficiency, consequently escalating the risk of infections, tumors, and age-associated disorders. Lymphocytes, especially T cells, are subject to both replicative and premature senescence. Telomerase reverse transcriptase (TERT) and telomerase have multifaceted roles in regulating cellular behavior, possessing the ability to counteract both replicative and premature senescence in lymphocytes. This review encapsulates recent advancements in understanding immunosenescence, with a focus on T cell senescence, and the regulatory mechanisms involving TERT/telomerase. Additionally, it comprehensively discusses strategies aimed at inhibiting immunosenescence by augmenting TERT/telomerase activity.

A rare homozygous variant in TERT gene causing variable bone marrow failure, fragility fractures, rib anomalies and extremely short telomere lengths with high serum IgE

By whole exome sequencing, we identified a homozygous c.2086 C→T (p.R696C) TERT mutation in patients who present with a spectrum of variable bone marrow failure (BMF), raccoon eyes, dystrophic nails, rib anomalies, fragility fractures (FFs), high IgE level, extremely short telomere lengths (TLs), and skewed numbers of cytotoxic T cells with B and NK cytopenia. Haploinsufficiency in the other family members resulted in short TL and osteopenia. These patients also had the lowest bone mineral density Z-score compared to other BMF-patients. Danazol/zoledronic acid improved the outcomes of BMF and FFs. This causative TERT variant has been observed in one family afflicted with dyskeratosis congenita (DC), and thus, we also define a second report and new phenotype related to the variant which should be suspected in severe cases of DC with co-existent BMF, FFs, high IgE level and rib anomalies.

A pan-cancer analysis of Dyskeratosis congenita 1 (DKC1) as a prognostic biomarker

BACKGROUND

Dyskeratosis congenita 1 (DKC1), a critical component of telomerase complex, is highly expressed in a variety of human cancers. However, the association of DKC1 with cancer occurrence and development stages is not clear, making a pan-cancer analysis crucial.

METHODS

We conducted a study using various bioinformatic databases such as TIMER, GEPIA, UALCAN, and KM plotter Analysis to examine the different expressions of DKC1 in multiple tissues and its correlation with pathological stages. Through KEGG analysis, GO enrichment analysis and Venn analysis, we were able to reveal DKC1-associated genes and signaling pathways. In addition, we performed several tests including the CCK, wound healing assay, cell cycle arrest assay, transwell assay and Sa-β-gal staining on DKC1-deleted MDA-231 cells.

RESULTS

Our study demonstrates that DKC1 has relatively low expression specificity in different tissues. Furthermore, we found that in ACC, KICH, KIRP and LIHC, the expression level of DKC1 is positively correlated with pathological stages. Conversely, in NHSC, KIRP, LGG, LIHC, MESO and SARC, we observed a negative influence of DKC1 expression level on the overall survival rate. We also found a significant positive correlation between DKC1 expression and Tumor Mutational Burden in 14 tumors. Additionally, we observed a significantly negative impact of DKC1 DNA methylation on gene expression at the promoter region in BRCA. We also identified numerous phosphorylation sites concentrated at the C-terminus of the DKC1 protein. Our GO analysis revealed a correlation between DKC1 and ribosomal biosynthesis pathways, and the common element UTP14A was identified. We also observed decreased rates of cell proliferation, migration and invasion abilities in DKC1-knockout MDA-MB-231 cell lines. Furthermore, DKC1-knockout induced cell cycle arrest and caused cell senescence.

CONCLUSIONS

Our findings suggest that the precise expression of DKC1 is closely associated with the occurrence and developmental stages of cancer in multiple tissues. Depletion of DKC1 can inhibit the abilities of cancer cells to proliferate, migrate, and invade by arresting the cell cycle and inducing cell senescence. Therefore, DKC1 may be a valuable prognostic biomarker for the diagnosis and treatment of cancer in various tissues.

Inherited bone marrow failure syndromes: a review of current practices and potential future research directions

PURPOSE OF REVIEW

Recent advances in diagnosis and treatment of inherited bone marrow failure syndromes (IBMFS) have significantly improved disease understanding and patient outcomes. Still, IBMFS present clinical challenges that require further progress. This review aims to provide an overview of the current state of diagnosis and treatment modalities of the major IBMFS seen in paediatrics and present areas of prioritization for future research.

RECENT FINDINGS

Haematopoietic cell transplantation (HCT) for IBMFS has greatly improved in recent years, shifting the research and clinical focus towards cancer predispositions and adverse effects of treatment. Each year, additional novel genes and pathogenic variants are described, and genotype-phenotype mapping becomes more sophisticated. Moreover, novel therapeutics exploring disease-specific mechanisms show promise to complement HCT and treat patients who cannot undergo current treatment options.

SUMMARY

Research on IBMFS should have short-term and long-term goals. Immediate challenges include solidifying diagnostic and treatment guidelines, cancer detection and treatment, and continued optimization of HCT. Long-term goals should emphasize genotype-phenotype mapping, genetic screening tools and gene-targeted therapy.

Construction of m7G subtype classification on heterogeneity of sepsis

Sepsis is a highly heterogeneous disease and a major factor in increasing mortality from infection. N7-Methylguanosine (m7G) is a widely RNA modification in eukaryotes, which involved in regulation of different biological processes. Researchers have found that m7G methylation contributes to a variety of human diseases, but its research in sepsis is still limited. Here, we aim to establish the molecular classification of m7G gene-related sepsis, reveal its heterogeneity and explore the underlying mechanism. We first identified eight m7G related prognostic genes, and identified two different molecular subtypes of sepsis through Consensus Clustering. Among them, the prognosis of C2 subtype is worse than that of C1 subtype. The signal pathways enriched by the two subtypes were analyzed by ssGSEA, and the results showed that the amino acid metabolism activity of C2 subtype was more active than that of C1 subtype. In addition, the difference of immune microenvironment among different subtypes was explored through CIBERSORT algorithm, and the results showed that the contents of macrophages M0 and NK cells activated were significantly increased in C2 subtype, while the content of NK cells resting decreased significantly in C2 subtype. We further explored the relationship between immune regulatory genes and inflammation related genes between C2 subtype and C1 subtype, and found that C2 subtype showed higher expression of immune regulatory genes and inflammation related genes. Finally, we screened the key genes in sepsis by WGCNA analysis, namely NUDT4 and PARN, and verified their expression patterns in sepsis in the datasets GSE131761 and GSE65682. The RT-PCR test further confirmed the increased expression of NUDTA4 in sepsis patients. In conclusion, sepsis clustering based on eight m7G-related genes can well distinguish the heterogeneity of sepsis patients and help guide the personalized treatment of sepsis patients.

Case Report: A Missense Mutation in Dyskeratosis Congenita 1 Leads to a Benign Form of Dyskeratosis Congenita Syndrome With the Mucocutaneous Triad

BACKGROUND

Dyskeratosis congenita (DC) is a rare inheritable disorder characterized by bone marrow failure and mucocutaneous triad (reticular skin pigmentation, nail dystrophy, and oral leukoplakia). Dyskeratosis congenita 1 (DKC1) is responsible for 4.6% of the DC with an X-linked inheritance pattern. Almost 70 DKC1 variations causing DC have been reported in the Human Gene Mutation Database.

RESULTS

Here we described a 14-year-old boy in a Chinese family with a phenotype of abnormal skin pigmentation on the neck, oral leukoplakia, and nail dysplasia in his hands and feet. Genetic analysis and sequencing revealed hemizygosity for a recurrent missense mutation c.1156G > A (p.Ala386Thr) in DKC1 gene. The heterozygous mutation (c.1156G > A) from his mother and wild-type sequence from his father were obtained in the same site of DKC1. This mutation was determined as disease causing based on silico software, but the pathological phenotypes of the proband were milder than previously reported at this position (HGMDCM060959). Homology modeling revealed that the altered amino acid was located near the PUA domain, which might affect the affinity for RNA binding.

CONCLUSION

This DKC1 mutation (c.1156G > A, p.Ala386Thr) was first reported in a Chinese family with mucocutaneous triad phenotype. Our study reveals the pathogenesis of DKC1 c.1156G > A mutation to DC with a benign phenotype, which expands the disease variation database, the understanding of genotype-phenotype correlations, and facilitates the clinical diagnosis of DC in China.

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

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.