scholarly journals CHIP: is clonal hematopoiesis a surrogate for aging and other disease?

Hematology ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. 384-389
Author(s):  
Lukasz P. Gondek

Abstract Somatic mutations are an unavoidable consequence of aging tissues. Even though most mutations are functionally silent, some may affect genes critical to proper tissue self-renewal and differentiation, resulting in the outgrowth of affected cells, also known as clonal expansion. In hematopoietic tissue such clonal dominance is known as clonal hematopoiesis (CH). Sporadic CH is frequent in aging and affects over 10% of individuals beyond the fifth decade of life. It has been associated with an increased risk of hematologic malignancies and cardiovascular disease. In addition to aging, CH has been observed in other hematologic conditions and confers an adaptation of hematopoietic stem cells (HSCs) to various environmental stressors and cell-intrinsic defects. In the presence of extrinsic stressors such as genotoxic therapies, T-cell-mediated immune attack, or inflammation, somatic mutations may result in augmentation of HSC fitness. Such attuned HSCs can evade the environmental insults and outcompete their unadapted counterparts. Similarly, in inherited bone marrow failures, somatic mutations in HSCs frequently lead to the reversion of inherited defects. This may occur via the direct correction of germline mutations or indirect compensatory mechanisms. Occasionally, such adaptation may involve oncogenes or tumor suppressors, resulting in malignant transformation. In this brief article, we focus on the mechanisms of clonal dominance in various clinical and biological contexts.

2017 ◽  
Vol 1 (26) ◽  
pp. 2572-2578 ◽  
Author(s):  
Stephen S. Chung ◽  
Christopher Y. Park

Abstract The aging hematopoietic system undergoes numerous changes, including reduced production of red blood cells and lymphocytes as well as a relative increase in the production of myeloid cells. Emerging evidence indicates that many of these changes are due to selection pressures from cell-intrinsic and cell-extrinsic factors that result in clonal shifts in the hematopoietic stem cell (HSC) pool, resulting in predominant HSC clones that exhibit the functional characteristics associated with HSC aging. Given the recent descriptions of clonal hematopoiesis in aged populations, the increased risk of developing hematologic malignancies in individuals with clonal hematopoiesis, and the many similarities in hematopoietic aging and acquired bone marrow failure (BMF) syndromes, such as myelodysplastic syndromes (MDS), this raises significant questions regarding the relationship between aging hematopoiesis and MDS, including the factors that regulate HSC aging, whether clonal hematopoiesis is required for the development of MDS, and even whether BMF is an inevitable consequence of aging. In this article, we will review our current understanding of these processes and the potential intersections among them.


Hematology ◽  
2017 ◽  
Vol 2017 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Stephen S. Chung ◽  
Christopher Y. Park

Abstract The aging hematopoietic system undergoes numerous changes, including reduced production of red blood cells and lymphocytes as well as a relative increase in the production of myeloid cells. Emerging evidence indicates that many of these changes are due to selection pressures from cell-intrinsic and cell-extrinsic factors that result in clonal shifts in the hematopoietic stem cell (HSC) pool, resulting in predominant HSC clones that exhibit the functional characteristics associated with HSC aging. Given the recent descriptions of clonal hematopoiesis in aged populations, the increased risk of developing hematologic malignancies in individuals with clonal hematopoiesis, and the many similarities in hematopoietic aging and acquired bone marrow failure (BMF) syndromes, such as myelodysplastic syndromes (MDS), this raises significant questions regarding the relationship between aging hematopoiesis and MDS, including the factors that regulate HSC aging, whether clonal hematopoiesis is required for the development of MDS, and even whether BMF is an inevitable consequence of aging. In this article, we will review our current understanding of these processes and the potential intersections among them.


Leukemia ◽  
2021 ◽  
Author(s):  
Malte von Bonin ◽  
Helena Klara Jambor ◽  
Raphael Teipel ◽  
Friedrich Stölzel ◽  
Christian Thiede ◽  
...  

AbstractThe accumulation of somatic mutations in hematopoietic stem cells during aging, leading to clonal expansion, is linked to a higher risk of cardiovascular mortality and hematologic malignancies. Clinically, clonal hematopoiesis is associated with a pro-inflammatory phenotype of hematopoietic cells and their progeny, inflammatory conditions and a poor outcome for patients with hematologic neoplasms and solid tumors. Here, we review the relevance and complications of clonal hematopoiesis for the treatment of hematologic malignancies with cell therapeutic approaches. In autologous and allogeneic hematopoietic stem cell transplantation native hematopoietic and immune effector cells of clonal origin are transferred, which may affect outcome of the procedure. In chimeric antigen receptor modified T-cell therapy, the effectiveness may be altered by preexisting somatic mutations in genetically modified effector cells or by unmodified bystander cells harboring clonal hematopoiesis. Registry studies and carefully designed prospective trials will be required to assess the relative roles of donor- and recipient-derived individual clonal events for autologous and allogeneic cell therapies and to incorporate novel insights into therapeutic strategies.


2020 ◽  
Author(s):  
Kira Young ◽  
Elizabeth Eudy ◽  
Rebecca Bell ◽  
Matthew Loberg ◽  
Tim Stearns ◽  
...  

AbstractHematopoietic stem cells (HSCs) are responsible for lifelong maintenance and regeneration of the blood system. With aging, loss of HSC function is a major contributor to decline in overall hematopoietic function, leading to increased rate of infection, poor vaccination response, clonal hematopoiesis, and increased risk of hematologic malignancies. While cellular and molecular hallmarks of HSC aging have been defined1–3, the lack of understanding of the nature and timing of the initiating events that cause HSC aging is a barrier to achieving the goal of extending healthy hematopoietic function into older age. Here we discover that hallmarks of HSC aging and myeloid-biased hematopoiesis accumulate by middle age in mice, and that the bone marrow (BM) microenvironment at middle age induces and is indispensable for hematopoietic aging phenotypes. Using unbiased transcriptome-based approaches, we identify decreased production of IGF1 by cells in the middle-aged BM microenvironment as a factor causing hematopoietic stem and progenitor cell aging and show that direct stimulation with IGF1 rescues hallmarks of hematopoietic aging. Declining IGF1 in the BM microenvironment at middle age represents a compelling target for intervention using prophylactic therapies to effectively extend healthspan and to prevent functional decline during aging.


2020 ◽  
Author(s):  
Kelly L. Bolton ◽  
Youngil Koh ◽  
Michael B. Foote ◽  
Hogune Im ◽  
Justin Jee ◽  
...  

ABSTRACTAcquired somatic mutations in hematopoietic stem and progenitor cells (clonal hematopoiesis or CH) are associated with advanced age, increased risk of cardiovascular and malignant diseases, and decreased overall survival.1–4 These adverse sequelae may be mediated by altered inflammatory profiles observed in patients with CH.2,5,6 A pro-inflammatory immunologic profile is also associated with worse outcomes of certain infections, including SARS-CoV-2 and its associated disease Covid-19.7,8 Whether CH predisposes to severe Covid-19 or other infections is unknown. Among 515 individuals with Covid-19 from Memorial Sloan Kettering (MSK) and the Korean Clonal Hematopoiesis (KoCH) consortia, we found that CH was associated with severe Covid-19 outcomes (OR=1.9, 95%=1.2-2.9, p=0.01). We further explored the relationship between CH and risk of other infections in 14,211 solid tumor patients at MSK. CH was significantly associated with risk of Clostridium Difficile (HR=2.0, 95% CI: 1.2-3.3, p=6×10−3) and Streptococcus/Enterococcus infections (HR=1.5, 95% CI=1.1-2.1, p=5×10−3). These findings suggest a relationship between CH and risk of severe infections that warrants further investigation.


Blood ◽  
2020 ◽  
Author(s):  
Siddhartha Jaiswal

Clonal expansions of mutated hematopoietic cells, termed clonal hematopoiesis, are common in aging humans. One expected consequence of mutation-associated clonal hematopoiesis is an increased risk of hematologic cancers, which has now been shown in several studies. However, the hematopoietic stem cells that acquire these somatic mutations also give rise to mutated immune effector cells, such as monocytes, granulocytes, and lymphocytes. These effector cells can potentially influence many disease states, especially those with a chronic inflammatory component. Indeed, several studies have now shown that clonal hematopoiesis associates with increased risk of atherosclerotic cardiovascular disease. Emerging data also associate clonal hematopoiesis to other non-hematologic diseases. Here, we will review recent studies linking clonal hematopoiesis to altered immune function, inflammation, and non-malignant diseases of aging.


Author(s):  
Oriol Pich ◽  
Iker Reyes-Salazar ◽  
Abel Gonzalez-Perez ◽  
Nuria Lopez-Bigas

AbstractMutations in genes that confer a selective advantage to hematopoietic stem cells (HSCs) in certain conditions drive clonal hematopoiesis (CH). While some CH drivers have been identified experimentally or through epidemiological studies, the compendium of all genes able to drive CH upon mutations in HSCs is far from complete. We propose that identifying signals of positive selection in blood somatic mutations may be an effective way to identify CH driver genes, similarly as done to identify cancer genes. Using a reverse somatic variant calling approach, we repurposed whole-genome and whole-exome blood/tumor paired samples of more than 12,000 donors from two large cancer genomics cohorts to identify blood somatic mutations. The application of IntOGen, a robust driver discovery pipeline, to blood somatic mutations across both cohorts, and more than 24,000 targeted sequenced samples yielded a list of close to 70 genes with signals of positive selection in CH, available at http://www.intogen.org/ch. This approach recovers all known CH genes, and discovers novel candidates. Generating this compendium is an essential step to understand the molecular mechanisms of CH and to accurately detect individuals with CH to ascertain their risk to develop related diseases.


Blood ◽  
2020 ◽  
Vol 135 (18) ◽  
pp. 1548-1559 ◽  
Author(s):  
Steffen Boettcher ◽  
C. Matthias Wilk ◽  
Jochen Singer ◽  
Fabian Beier ◽  
Elodie Burcklen ◽  
...  

Abstract Clonal hematopoiesis (CH) is associated with age and an increased risk of myeloid malignancies, cardiovascular risk, and all-cause mortality. We tested for CH in a setting where hematopoietic stem cells (HSCs) of the same individual are exposed to different degrees of proliferative stress and environments, ie, in long-term survivors of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and their respective related donors (n = 42 donor-recipient pairs). With a median follow-up time since allo-HSCT of 16 years (range, 10-32 years), we found a total of 35 mutations in 23 out of 84 (27.4%) study participants. Ten out of 42 donors (23.8%) and 13 out of 42 recipients (31%) had CH. CH was associated with older donor and recipient age. We identified 5 cases of donor-engrafted CH, with 1 case progressing into myelodysplastic syndrome in both donor and recipient. Four out of 5 cases showed increased clone size in recipients compared with donors. We further characterized the hematopoietic system in individuals with CH as follows: (1) CH was consistently present in myeloid cells but varied in penetrance in B and T cells; (2) colony-forming units (CFUs) revealed clonal evolution or multiple independent clones in individuals with multiple CH mutations; and (3) telomere shortening determined in granulocytes suggested ∼20 years of added proliferative history of HSCs in recipients compared with their donors, with telomere length in CH vs non-CH CFUs showing varying patterns. This study provides insight into the long-term behavior of the same human HSCs and respective CH development under different proliferative conditions.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1541-1541
Author(s):  
Angela R. Smith ◽  
Erica D. Warlick ◽  
Rachel K. Fonstad ◽  
Michelle A. Roesler ◽  
Jenny N. Poynter ◽  
...  

Abstract Background MDS is a clonal hematopoietic stem cell disorder characterized by dysplastic changes in the bone marrow, ineffective hematopoiesis and an increased risk for developing acute myeloid leukemia (AML). The majority of MDS cases are sporadic, but rare familial cases have been described and are often ascertained through clinic-based referrals. To our knowledge, no population based study of MDS has examined the frequency of family history of hematologic malignancies and disorders in patients, nor associations with disease characteristics and outcomes. Methods Newly diagnosed MDS cases are being identified by rapid case ascertainment by the Minnesota Cancer Surveillance System (MCSS), a population-based cancer registry in Minnesota. Eligibility criteria include all newly diagnosed cases of MDS during the period April 1, 2010-October 31, 2014, between 20-85 years, Minnesota resident, and ability to understand English or Spanish. Proxy interviews are not being conducted. Medical records and biologic samples are obtained and questionnaires are filled out by participants. Centralized pathology and cytogenetics review confirm diagnosis and classify by subtype and risk score including the Revised International Prognostic Scoring System (IPSS-R). Since 2010, information on family history has been obtained through questionnaire responses and/or medical record review on 353 MDS patients. Cases were considered to have a positive family history if they reported a first degree relative with MDS, leukemia, lymphoma or other hematologic condition (multiple myeloma [n=4], Waldenstrom’s macroglobulinemia [n=1] and idiopathic thrombocytopenic purpura [n=1]). Treatment related MDS cases were excluded leaving 330 MDS patients for analysis. Unconditional logistic regression was used to calculate crude odds ratios (ORs) and 95% confidence intervals (CI) overall and by sex. Results A total of 61/330 (18.5%) cases reported a family history of a hematologic condition. The mean age at diagnosis was 71.3 years in those with a family history compared to 72.2 years in those without a family history (p=0.53). There was no difference in the sex distribution between the two groups. Though not statistically significant, the odds of having abnormal cytogenetics or an IPSS-R of High/Very High was lower for those having a positive family history (OR 0.57 [CI 0.25-1.33, p=0.19 and 0.67 [CI 0.24-1.84, p=0.29], respectively). The odds of survival at one year after diagnosis was significantly higher in those with a family history (OR 2.79 [CI 1.04-7.51, p=0.04]) compared to those without (Table). Further stratification by sex revealed that this association was strongest for males (OR=4.23, [CI 0.94-19.0, p=0.06] compared to females (OR=1.84 [CI=0.47-7.19, p=0.38]). Discussion In this population based study of adults with MDS, the prevalence of MDS cases having a positive family history was higher than previous reports. Additionally, cases reporting a family history of hematologic malignancies and disorders appear to experience lower risk disease and have significantly improved overall survival, especially males. It is possible that patients with a family history of hematologic conditions are diagnosed earlier in the course of their disease secondary to increased awareness about blood disorders and/or more active screening within the family. Our analysis is limited by relatively small numbers, but enrollment is ongoing so subsequent analyses with larger numbers of subjects may be more revealing. Additionally, a prospective study to examine these families further, including detailed medical histories and collection of biospecimens (saliva, blood, skin) for genetic analyses is underway in order to identify potential mechanisms and mutations involved in the development of MDS and progression to AML. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3894-3894
Author(s):  
Tatsuya Imi ◽  
Takamasa Katagiri ◽  
Kazuyoshi Hosomichi ◽  
Noriharu Nakagawa ◽  
Yoshitaka Zaimoku ◽  
...  

Abstract [Background] Clonal hematopoiesis is currently known to be common in patients with acquired aplastic anemia (AA). One of the most common abnormalities underlying clonal hematopoiesis in AA patients is copy-number neutral loss of heterozygosity (LOH) in the short of 6 chromosome (6pLOH) caused by acquired uniparental disomy. Hematopoietic stem/progenitor cells (HSPCs) having undergone 6pLOH are thought to evade attack by cytotoxic T lymphocytes (CTLs) specific to auto-antigens by lacking particular HLA-A alleles. These HSPCs then produce HLA class I allele-lacking [HLA(-)] leukocytes to support hematopoiesis in patients with AA patients in remission. Our recent study showed that HLA(-) granulocytes are detected in about 24% of newly-diagnosed AA patients, and the aberrant granulocytes often account for more than 95% of the total granulocytes and persist for many years. The sustainability of 6pLOH(+) HSPC clones suggests that these HSPCs may suffer from secondary somatic mutations that confer a proliferative advantage on them over normal HSPCs. Alternatively, 6pLOH(+) HSPCs may persist and continue to support hematopoiesis according to their inherent sustainability, just like the PIGA mutant HSPCs we previously described (Katagiri et al. Stem Cells, 2013). To test these hypotheses, we determined the sequences of genes associated with the clonal expansion of HSPCs in HLA(-) granulocytes. [Patients and Methods] Eleven AA patients whose percentages of HLA(-) granulocytes ranged 6.4%-99.8% (median 94.2%) of the total granulocyte population were chosen for this study. The patients (male/female, 5/6 and age 27-79 [median 53] years) had been diagnosed with severe (n=5) or non-severe (n=6) AA 2-25 [median 12.5] years earlier, and 7 and 4 patients achieved complete response and partial response, respectively after treatments with cyclosporine (CsA) alone (n=4), CsA+antithymocyte globulin (ATG, n=3), CsA+anabolic steroids (AS, n=2), AS+romiplostim (n=1), and AS alone (n=1). The lineage combinations of HLA(-) cells were granulocyte, monocytes, B cells and T cells (GMBT) in 6, GMB in 4 and GM in 1. HLA(-) and normal [HLA(+)] granulocytes were sorted from the blood leukocytes of the 11 patients and the DNA of each cell population as well as that of buccal mucosa cells was subjected to target sequencing of 61 myelodysplastic syndrome (MDS)-related genes with MiSeq. DNA samples from 5 patients including 4 patients whose HLA(-) cell percentages were greater than 95% were further analyzed by whole-exome sequencing (WES) using HiSeq. The percentage of 6pLOH(+) cells in the total granulocytes or sorted HLA(-) granulocytes were estimated using digital droplet PCR or deep sequencing of HLA alleles. [Results] Target sequencing of 8 of the 11 patients revealed somatic mutations in the HLA(-) granulocytes of 3 patients. HLA(-) granulocytes-specific mutations were found in DNMT3A, PRR5L, SMC3A, and LRCH1 (Table). The variant allele frequencies (VAF) of these mutations were far lower (5.1%-20%) than those of HLA(-) granulocytes that accounted for 95% of sorted cells. WES revealed 22 non-synonymous and 9 synonymous mutations in the HLA(-) granulocytes from 4 of the 5 patientsthat included 3 new patients and 2 patients whose samples were negative for mutations revealed by the target sequencing. The VAF of these mutations ranged from 20.7-52.5% (median 44.1%, Table). Very-high VAFs of several mutant genes suggested that these mutations occurred simultaneously with or soon after the occurrence of 6pLOH. A patient who achieved remission after romiplostim therapy without ATG showed various gene mutations that were thought to have occurred after 6pLOH. Despite of their highly biased hematopoiesis supported by single or few clones, recurrent or MDS-related oncogenic mutations were not detected in any of the 11 patients. Of note, the percentages of 6pLOH(+) cells in the sorted HLA(-) granulocytes were ≤75% (36.7%, 46%, 74%, and 75%) in 4 patients, indicating the presence of granulocytes lacking HLA-A alleles through mechanisms other than 6pLOH. [Conclusions] HLA(-) HSPCs caused by 6pLOH or other unknown mechanisms support long-term hematopoiesis without the development of oncogenic driver mutations that are associated with clonal hematopoiesis of MDS; as such, clonal hematopoiesis by 6pLOH(+) HSPCs may not portend a poor prognosis. Disclosures Nakao: Alexion Pharmaceuticals: Honoraria, Research Funding.


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