Neutrophil-mediated innate immune resistance to bacterial pneumonia is dependent on Tet2 function

Individuals with clonal hematopoiesis of indeterminate potential (CHIP) are at increased risk of aging related health conditions and all-cause mortality, but whether CHIP impacts risk of infection is much less clear. Using UK Biobank data, we revealed a positive association between CHIP and incident pneumonia in 438,421 individuals. We show that inflammation enhanced pneumonia risk, as CHIP carriers with a hypomorphic IL6 receptor polymorphism were protected. To better characterize the pathways of susceptibility, we challenged hematopoietic Tet Methylcytosine Dioxygenase 2 knockout (Tet2-/-) and floxed control mice (Tet2f/f) with Streptococcus pneumoniae. As with human CHIP carriers, Tet2-/- mice had hematopoietic abnormalities resulting in the expansion of inflammatory monocytes and neutrophils in peripheral blood. Yet, these cells were insufficient in defending against S. pneumoniae and resulted in increased pathology, impaired bacterial clearance, and higher mortality in Tet2-/- mice. We delineated the transcriptional landscape of Tet2-/- neutrophils and found that while inflammation-related pathways were upregulated in Tet2-/- neutrophils, migration and motility pathways were compromised. Using live-imaging techniques, we demonstrated impairments in motility, pathogen uptake and neutrophil extracellular trap (NET) formation by Tet2-/- neutrophils. Collectively, we show that CHIP is a risk factor for bacterial pneumonia related to innate immune impairments.

Clonal hematopoiesis of indeterminate potential is associated with acute kidney injury

Age is a predominant risk factor for acute kidney injury (AKI), yet the biological mechanisms underlying this risk are largely unknown. Clonal hematopoiesis of indeterminate potential (CHIP) confers increased risk for several chronic diseases associated with aging. Here we sought to test whether CHIP increases the risk of AKI. In three population-based epidemiology cohorts, we found that CHIP was associated with a greater risk of incident AKI, which was more pronounced in patients with AKI requiring dialysis and in individuals with somatic mutations in genes other than DNMT3A, including mutations in TET2 and JAK2. Mendelian randomization analyses supported a causal role for CHIP in promoting AKI. Non-DNMT3A-CHIP was also associated with a nonresolving pattern of injury in patients with AKI. To gain mechanistic insight, we evaluated the role of Tet2-CHIP and Jak2V617F-CHIP in two mouse models of AKI. In both models, CHIP was associated with more severe AKI, greater renal proinflammatory macrophage infiltration and greater post-AKI kidney fibrosis. In summary, this work establishes CHIP as a genetic mechanism conferring impaired kidney function recovery after AKI via an aberrant inflammatory response mediated by renal macrophages.

Clonal haematopoiesis, ageing and kidney disease

Clonal haematopoiesis of indeterminate potential (CHIP) is a preclinical condition wherein a sizeable proportion of an individual's circulating blood cells are derived from a single mutated haematopoietic stem cell. CHIP occurs frequently with ageing - more than 10% of individuals over 65 years of age are affected - and is associated with an increased risk of disease across several organ systems and premature death. Emerging evidence suggests that CHIP has a role in kidney health, including associations with predisposition to acute kidney injury, impaired recovery from acute kidney injury and kidney function decline, both in the general population and among those with chronic kidney disease. Beyond its direct effect on the kidney, CHIP elevates the susceptibility of individuals to various conditions that can detrimentally affect the kidneys, including cardiovascular disease, obesity and insulin resistance, liver disease, gout, osteoporosis and certain autoimmune diseases. Aberrant pro-inflammatory signalling, telomere attrition and epigenetic ageing are potential causal pathophysiological pathways and mediators that underlie CHIP-related disease risk. Experimental animal models have shown that inhibition of inflammatory cytokine signalling can ameliorate many of the pathological effects of CHIP, and assessment of the efficacy and safety of this class of medications for human CHIP-associated pathology is ongoing.

Clonal hematopoiesis of indeterminate potential-associated non-small cell lung cancer risk is potentiated by small particulate matter air pollution among non-smokers: a novel somatic variant-environment interaction

Small particulate matter air pollution (PM 2.5 ) is a recognized driver of non-small cell lung cancer (NSCLC) among non-smoking individuals. Inhaled PM 2.5 recruits pro-inflammatory macrophages to the air-lung interface, which promotes malignant lung epithelial cell growth and progression to overt cancer. We sought to determine whether clonal hematopoiesis of indeterminate potential (CHIP), a common age-related condition characterized by hyperinflammatory macrophages, exacerbates PM 2.5 -associated NSCLC in non-smokers using genetic, environmental, and phenotypic data from 413,901 individuals in the UK Biobank. Among non-smokers, PM 2.5 is not associated with NSCLC and not associated with prevalence of CHIP, but CHIP is associated with a doubling of NSCLC risk (hazard ratio (HR) 2.01, 95% confidence interval (CI): 1.34-3.00). Moreover, CHIP-associated NSCLC risk is exacerbated in the setting of above-median PM 2.5 levels (HR 2.70, 95% CI: 1.60-4.55). PM 2.5 × CHIP is also associated with significantly greater markers of systemic inflammation (CRP, IL-6, and IL-1β) than expected. Altogether, these results suggest CHIP and PM 2.5 form a novel gene × environment interaction promoting NSCLC tumorigenesis in non-smokers.

Germline and Somatic Mutations in DNA Methyltransferase 3A (DNMT3A) Predispose to Pulmonary Arterial Hypertension (PAH) in Humans and Mice: Implications for Associated PAH

Background

Mutations are found in 10-20% of idiopathic PAH (IPAH) patients, but none are consistently identified in connective tissue disease-associated PAH (APAH), which accounts for ∼45% of PAH cases. TET2 mutations, a cause of clonal hematopoiesis of indeterminant potential (CHIP), predispose to an inflammatory type of PAH. We now examine mutations in another CHIP gene, DNMT3A , in PAH.

Methods

We assessed DNMT3A mutation prevalence in PAH Biobank subjects as compared with controls, first using whole exome sequencing (WES)-derived CHIP calls in 1832 PAH Biobank patients versus 7509 age-and sex-matched gnomAD controls. We then performed deep, targeted panel sequencing of CHIP genes on a subset of 710 PAH Biobank patients and compared the prevalence of DNMT3A mutations therein to an independent pooled control cohort (N = 3645). In another cohort of 80 PAH patients and 41 controls, DNMT3A mRNA expression was studied in peripheral blood mononuclear cells (PBMCs). Finally, we evaluated the development of PAH in a conditional, hematopoietic, Dnmt3a knockout mouse model.

Results

DNMT3A mutations were more frequent in PAH cases versus control subjects in the WES dataset (OR 2.60, 95% CI: 1.71-4.27). Among PAH patients, 33 had DNMT3A variants, most of whom had APAH (21/33). While 21/33 had somatic mutations (female:male 17:4), germline variants occurred in 12/33 (female:male 11:1). Hemodynamics were comparable with and without DNMT3A mutations (mPAP=58±21 vs. 52±18 mmHg); however, patients with DNMT3A mutations were unresponsive to acute vasodilator testing. Targeted panel sequencing identified that 14.6% of PAH patients had CHIP mutations (104/710), with DNMT3A accounting for 49/104. There was a significant association between all CHIP mutations and PAH in analyses adjusted for age and sex (OR 1.40, 95% CI: 1.09-1.80), though DNMT3A CHIP alone was not significantly enriched (OR:1.15, 0.82-1.61). DNMT3A expression was reduced in patient-derived versus control PAH-PBMCs. Spontaneous PAH developed in Dnmt3a -/- mice, and it was exacerbated by 3 weeks of hypoxia. Dnmt3a -/- mice had increased lung macrophages and elevated plasma IL-13. The IL-1β antibody canakinumab attenuated PAH in Dnmt3a -/- mice.

Conclusions

Germline and acquired DNMT3A variants predispose to PAH in humans. DNMT3A mRNA expression is reduced in human PAH PBMCs. Hematopoietic depletion of Dnmt3a causes inflammatory PAH in mice. DNMT3A is a novel APAH gene and may be a biomarker and therapeutic target.

The Role of Clonal Hematopoiesis of Indeterminant Potential and DNA (Cytosine-5)-Methyltransferase Dysregulation in Pulmonary Arterial Hypertension and Other Cardiovascular Diseases

DNA methylation is an epigenetic mechanism that regulates gene expression without altering gene sequences in health and disease. DNA methyltransferases (DNMTs) are enzymes responsible for DNA methylation, and their dysregulation is both a pathogenic mechanism of disease and a therapeutic target. DNMTs change gene expression by methylating CpG islands within exonic and intergenic DNA regions, which typically reduces gene transcription. Initially, mutations in the DNMT genes and pathologic DNMT protein expression were found to cause hematologic diseases, like myeloproliferative disease and acute myeloid leukemia, but recently they have been shown to promote cardiovascular diseases, including coronary artery disease and pulmonary hypertension. We reviewed the regulation and functions of DNMTs, with an emphasis on somatic mutations in DNMT3A, a common cause of clonal hematopoiesis of indeterminant potential (CHIP) that may also be involved in the development of pulmonary arterial hypertension (PAH). Accumulation of somatic mutations in DNMT3A and other CHIP genes in hematopoietic cells and cardiovascular tissues creates an inflammatory environment that promotes cardiopulmonary diseases, even in the absence of hematologic disease. This review summarized the current understanding of the roles of DNMTs in maintenance and de novo methylation that contribute to the pathogenesis of cardiovascular diseases, including PAH.

Clonal Hematopoiesis: Updates and Implications at the Solid Tumor-Immune Interface

Recent larger-scale studies of patients with cancer and longitudinal population cohorts have revealed how age-related expansions of mutant hematopoietic cells (clonal hematopoiesis [CH]) have differential associations with incident and prevalent cancers and their outcomes. Increasing recognition and deeper understanding of genetic subtypes of CH are yielding insights into the tumor-immune interface that may help to explain the heterogeneous impact of CH on tumorigenesis and treatment. Herein, we update the expanding influence of CH in precision oncology and propose important research and clinical questions to address to effectively manage and harness CH in oncology patients.

Clonal Hematopoiesis of Indeterminate Potential is Associated with Acute Kidney Injury

Age is a predominant risk factor for acute kidney injury (AKI), yet the biological mechanisms underlying this risk are largely unknown and to date no genetic mechanisms for AKI have been established. Clonal hematopoiesis of indeterminate potential (CHIP) is a recently recognized biological mechanism conferring risk of several chronic aging diseases including cardiovascular disease, pulmonary disease and liver disease. In CHIP, blood stem cells acquire mutations in myeloid cancer driver genes such as DNMT3A, TET2, ASXL1 and JAK2 and the myeloid progeny of these mutated cells contribute to end-organ damage through inflammatory dysregulation. We sought to establish whether CHIP causes acute kidney injury (AKI). To address this question, we first evaluated associations with incident AKI events in three population-based epidemiology cohorts (N = 442,153). We found that CHIP was associated with a greater risk of AKI (adjusted HR 1.26, 95% CI: 1.19-1.34, p<0.0001), which was more pronounced in patients with AKI requiring dialysis (adjusted HR 1.65, 95% CI: 1.24-2.20, p=0.001). The risk was particularly high in the subset of individuals where CHIP was driven by mutations in genes other than DNMT3A (HR: 1.49, 95% CI: 1.37-1.61, p<0.0001). We then examined the association between CHIP and recovery from AKI in the ASSESS-AKI cohort and identified that non-DNMT3A CHIP was more common among those with a non-resolving pattern of injury (HR 2.3, 95% CI: 1.14-4.64, p = 0.03). To gain mechanistic insight, we evaluated the role of Tet2-CHIP to AKI in ischemia-reperfusion injury (IRI) and unilateral ureteral obstruction (UUO) mouse models. In both models, we observed more severe AKI and greater post-AKI kidney fibrosis in Tet2-CHIP mice. Kidney macrophage infiltration was markedly increased in Tet2-CHIP mice and Tet2-CHIP mutant renal macrophages displayed greater proinflammatory responses. In summary, this work establishes CHIP as a genetic mechanism conferring risk of AKI and impaired kidney function recovery following AKI via an aberrant inflammatory response in CHIP derived renal macrophages.

A DNA methylation based measure outperforms circulating CRP as a marker of chronic inflammation and partly reflects the monocytic response to long-term inflammatory exposure: A Canadian longitudinal study of aging analysis

A key hallmark in the age-related dysfunction of physiological systems is disruption related to the regulation of inflammation, often resulting in a chronic, low-grade inflammatory state (i.e., inflammaging). In order to understand the causes of overall system decline, methods to quantify the life-long exposure or damage related to chronic inflammation are critical. Here, we characterize a comprehensive epigenetic inflammation score (EIS) based on DNA methylation loci (CpGs) that are associated with circulating levels of C-reactive protein (CRP). In a cohort of 1446 older adults, we show that associations to age and health-related traits such as smoking history, chronic conditions, and established measures of accelerated aging were stronger for EIS than CRP, while the risk of longitudinal outcomes such as outpatient or inpatient visits and increased frailty were relatively similar. To determine whether variation in EIS actually reflects the cellular response to chronic inflammation we exposed THP1 myelo-monocytic cells to low levels of inflammatory mediators for 14 days, finding that EIS increased in response to both CRP (p = 0.011) and TNF (p = 0.068). Interestingly, a refined version of EIS based only on those CpGs that changed in vitro was more strongly associated with many of the aforementioned traits as compared to EIS. In conclusion, our study demonstrates that EIS outperforms circulating CRP with regard to its association to health-traits that are synonymous with chronic inflammation and accelerated aging, and substantiates its potential role as a clinically relevant tool for stratifying patient risk of adverse outcomes prior to treatment or following illness.

A practical approach to curate clonal hematopoiesis of indeterminate potential in human genetic data sets

Clonal hematopoiesis of indeterminate potential (CHIP) is a common form of age-related somatic mosaicism that is associated with significant morbidity and mortality. CHIP mutations can be identified in peripheral blood samples that are sequenced using approaches that cover the whole genome, the whole exome, or targeted genetic regions; however, differentiating true CHIP mutations from sequencing artifacts and germ line variants is a considerable bioinformatic challenge. We present a stepwise method that combines filtering based on sequencing metrics, variant annotation, and population-based associations to increase the accuracy of CHIP calls. We apply this approach to ascertain CHIP in ∼550 000 individuals in the UK Biobank complete whole exome cohort and the All of Us Research Program initial whole genome release cohort. CHIP ascertainment on this scale unmasks recurrent artifactual variants and highlights the importance of specialized filtering approaches for several genes, including TET2 and ASXL1. We show how small changes in filtering parameters can considerably increase CHIP misclassification and reduce the effect size of epidemiological associations. Our high-fidelity call set refines previous population-based associations of CHIP with incident outcomes. For example, the annualized incidence of myeloid malignancy in individuals with small CHIP clones is 0.03% per year, which increases to 0.5% per year among individuals with very large CHIP clones. We also find a significantly lower prevalence of CHIP in individuals of self-reported Latino or Hispanic ethnicity in All of Us, highlighting the importance of including diverse populations. The standardization of CHIP calling will increase the fidelity of CHIP epidemiological work and is required for clinical CHIP diagnostic assays.

Clonal Hematopoiesis of Indeterminate Potential and Kidney Function Decline in the General Population

RATIONALE & OBJECTIVE

Clonal hematopoiesis of indeterminate potential (CHIP), defined by the age-related ontogenesis of expanded leukemogenic variants indicative of a genetically distinct clonal leukocyte population, is associated with risk of hematologic malignancy and cardiovascular disease. In experimental models, recapitulation of CHIP promotes kidney interstitial fibrosis with direct tissue infiltration of donor macrophages. We tested the hypothesis that CHIP is associated with kidney function decline in the general population.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

12,004 individuals from 3 community-based cohorts in the TOPMed Consortium.

EXPOSURE

CHIP status from whole-genome sequences obtained from DNA extracted from peripheral blood.

OUTCOME

Risk of 30% decline in estimated glomerular filtration rate (eGFR) and percent eGFR decline per year during the follow-up period.

ANALYTICAL APPROACH

Cox proportional hazards models for 30% eGFR decline end point and generalized estimating equations for annualized relative change in eGFR with meta-analysis. Study-specific estimates were combined using fixed-effect meta-analysis.

RESULTS

The median baseline eGFR was 84mL/min/1.73m2. The prevalence of CHIP was 6.6%, 9.0%, and 12.2% in persons aged 50-60, 60-70, and>70 years, respectively. Over a median follow-up period of 8 years, for the 30% eGFR outcome 205 events occurred among 1,002 CHIP carriers (2.1 events per 100 person-years) and 2,041 events in persons without CHIP (1.7 events per 100 person-years). In meta-analysis, CHIP was associated with greater risk of a 30% eGFR decline (17% [95% CI, 1%-36%] higher; P=0.04). Differences were not observed between those with baseline eGFR above or below 60mL/min/1.73m2, of age above or below 60 years, or with or without diabetes.

LIMITATIONS

Small number of participants with moderate-to-advanced kidney disease and restricted set of CHIP driver variants.

CONCLUSIONS

We report an association between CHIP and eGFR decline in 3 general population cohorts without known kidney disease. Further studies are needed to investigate this novel condition and its potential impact among individuals with overt kidney disease.

A Lower Frequency of Spliceosome Mutations Distinguishes Clonal Cytopenias of Undetermined Significance From Low-Risk Myelodysplastic Syndromes, Despite Inherent Similarities in Genomic, Laboratory, and Clinical Features

Clonal cytopenias of undetermined significance (CCUS) are associated with an increased risk of developing a myelodysplastic syndrome (MDS); however, the mechanism and factors associated with evolution remain unclear. We propose that next-generation sequencing (NGS) of cytopenic cases with equivocal morphologic dysplasia will improve patient clinical care and that serial sequencing of such equivocal cases could identify the factors that predict evolution to MDS. We performed targeted NGS of samples from 193 individuals with confirmed or suspected MDS or MDS/myeloproliferative neoplasm, including sequential investigation for 28 individuals at the time of diagnosis and during follow-up. NGS facilitated the diagnosis of all suspicious cases as myeloid neoplasm (21%), CCUS (34%), or idiopathic cytopenias of undetermined significance (45%) when no variants were detected. We found that there was no significant difference in most measured clinical features or clonal phenotypes, such as cell counts, number of variants, variant allele frequencies, and overall survival, between CCUS and International Prognostic Scoring System-Revised-defined low-risk MDS. However, there was a significant difference in the types of variants between CCUS and low-risk MDS, with a significantly lower number of splicing factor mutations in CCUS cases (P < .001). Moreover, we observed an increased probability of evolution to MDS of individuals with CCUS compared with that in those with idiopathic cytopenias of undetermined significance over the first 5 years (P = .045). Our analyses revealed no conclusive pattern associating clonal expansion or the number of variants with the evolution of CCUS to MDS, perhaps further supporting the similarity of these diseases and the clinical importance of recognizing and formally defining CCUS as a category of precursor myeloid disease state in the next revision of the World Health Organization guidelines.

Expression of TCF3 target genes defines a subclass of diffuse large B-cell lymphoma characterized by up-regulation of MYC target genes and poor clinical outcome following R-CHOP therapy

TCF3 is a lymphopoietic transcription factor that acquires somatic driver mutations in diffuse large B-cell lymphoma (DLBCL). Hypothesizing that expression patterns of TCF3-regulated genes can inform clinical management, we found that unsupervised clustering analysis with 15 TCF3-regulated genes and eight additional ones resolved local DLBCL cases into two main clusters, denoted Groups A and B, of which Group A manifested inferior overall survival (OS, p = 0.0005). We trained a machine learning model to classify samples into the Groups based on expression of the 23 transcripts in an independent validation cohort of 569 R-CHOP-treated DLBCL cases. Group A overlapped with the ABC cell-of-origin subgroup but its prognostic power was superior. GSEA analysis demonstrated asymmetric expression of 30 gene sets between the Groups, pointing to biological differences. We present, validate and make available a novel method to assign DLBCL cases into biologically-distinct groups with divergent OS following R-CHOP therapy.

Association of Clonal Hematopoiesis of Indeterminate Potential with Worse Kidney Function and Anemia in Two Cohorts of Patients with Advanced Chronic Kidney Disease

BACKGROUND

Clonal hematopoiesis of indeterminate potential (CHIP) is an inflammatory premalignant disorder resulting from acquired genetic mutations in hematopoietic stem cells. This condition is common in aging populations and associated with cardiovascular morbidity and overall mortality, but its role in CKD is unknown.

METHODS

We performed targeted sequencing to detect CHIP mutations in two independent cohorts of 87 and 85 adults with an eGFR<60 ml/min per 1.73m2. We also assessed kidney function, hematologic, and mineral bone disease parameters cross-sectionally at baseline, and collected creatinine measurements over the following 5-year period.

RESULTS

At baseline, CHIP was detected in 18 of 87 (21%) and 25 of 85 (29%) cohort participants. Participants with CHIP were at higher risk of kidney failure, as predicted by the Kidney Failure Risk Equation (KFRE), compared with those without CHIP. Individuals with CHIP manifested a 2.2-fold increased risk of a 50% decline in eGFR or ESKD over 5 years of follow-up (hazard ratio 2.2; 95% confidence interval, 1.2 to 3.8) in a Cox proportional hazard model adjusted for age, sex, and baseline eGFR. The addition of CHIP to 2-year and 5-year calibrated KFRE risk models improved ESKD predictions. Those with CHIP also had lower hemoglobin, higher ferritin, and higher red blood cell mean corpuscular volume versus those without CHIP.

CONCLUSIONS

In this exploratory analysis of individuals with preexisting CKD, CHIP was associated with higher baseline KFRE scores, greater progression of CKD, and anemia. Further research is needed to define the nature of the relationship between CHIP and kidney disease progression.

The Myeloid-Kidney Interface in Health and Disease

Kidney homeostasis is highly dependent upon the correct functioning of myeloid cells. These cells form a distributed surveillance network throughout the kidney, where they play an integral role in the response to organ threat. Dysregulation of resident proinflammatory and profibrotic macrophages leads to kidney structural damage and scarring after kidney injury. Fibrosis throughout the kidney parenchyma contributes to the progressive functional decline observed in CKD, independent of the etiology. Circulating myeloid cells bearing intrinsic defects also affect the kidney substructures, such as neutrophils activated by autoantibodies that cause GN in ANCA-associated vasculitis. The kidney can also be affected by disorders of myelopoiesis, including myeloid leukemias (acute and chronic myeloid leukemias) and myelodysplastic syndromes. Clonal hematopoiesis of indeterminate potential is a common, newly recognized premalignant clinical entity characterized by clonal expansion of hyperinflammatory myeloid lineage cells that may have significant kidney sequelae. A number of existing therapies in CKD target myeloid cells and inflammation, including glucocorticoid receptor agonists and mineralocorticoid receptor antagonists. The therapeutic indications for these and other myeloid cell-targeted treatments is poised to expand as our understanding of the myeloid-kidney interface evolves.

Circulating Foamy Macrophages in the Golden Syrian Hamster (Mesocricetus auratus) Model of Leptospirosis

Leptospirosis is a world-wide zoonotic disease caused by pathogenic Leptospira and can be asymptomatic or can cause clinical signs ranging from influenza-like to multi-organ failure and death in severe cases. While species and strain specificity can play a major role in disease presentation, the hamster is susceptible to most leptospiral infections and is the model of choice for vaccine efficacy testing. During evaluation of blood smears from hamsters challenged with different species and strains of Leptospira, a circulating population of large, mononuclear, lipid-filled cells, most similar to foamy macrophages (FMs), was detected. Circulating FMs were identified by Giemsa staining and verified by scanning and transmission electron microscopy. FMs were found in the circulating blood of all Leptospira-challenged hamsters, indicating that the finding was not species or strain specific, although higher numbers of FMs tended to correlate with severity of disease. The unique finding of circulating FMs in the hamster model of leptospirosis can yield additional insights into the pathogenesis of leptospirosis and other diseases that induce circulating FMs.

Clonal hematopoiesis is associated with risk of severe Covid-19

Acquired 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. These adverse sequelae may be mediated by altered inflammatory profiles observed in patients with CH. A pro-inflammatory immunologic profile is also associated with worse outcomes of certain infections, including SARS-CoV-2 and its associated disease Covid-19. Whether CH predisposes to severe Covid-19 or other infections is unknown. Among 525 individuals with Covid-19 from Memorial Sloan Kettering (MSK) and the Korean Clonal Hematopoiesis (KoCH) consortia, we show that CH is associated with severe Covid-19 outcomes (OR = 1.85, 95%=1.15-2.99, p = 0.01), in particular CH characterized by non-cancer driver mutations (OR = 2.01, 95% CI = 1.15-3.50, p = 0.01). We further explore the relationship between CH and risk of other infections in 14,211 solid tumor patients at MSK. CH is significantly associated with risk of Clostridium Difficile (HR = 2.01, 95% CI: 1.22-3.30, p = 6×10-3) and Streptococcus/Enterococcus infections (HR = 1.56, 95% CI = 1.15-2.13, p = 5×10-3). These findings suggest a relationship between CH and risk of severe infections that warrants further investigation.

Validation, Implementation, and Clinical Impact of the Oncomine Myeloid Targeted-Amplicon DNA and RNA Ion Semiconductor Sequencing Assay

The identification of clinically significant genes recurrently mutated in myeloid malignancies necessitates expanding diagnostic testing with higher throughput, such as targeted next-generation sequencing. We present validation of the Thermo Fisher Oncomine Myeloid Next-Generation Sequencing Panel (OMP), targeting 40 genes and 29 fusion drivers recurrently mutated in myeloid malignancies. The study includes data from a sample exchange between two Canadian hospitals demonstrating high concordance for detection of DNA and RNA aberrations. Clinical validation demonstrates high accuracy, sensitivity, and specificity of the OMP, with a lower limit of detection of 5% for single-nucleotide variants and 10% for insertions/deletions. Prospective sequencing was performed for 187 samples from 168 unique patients presenting with suspected or confirmed myeloid malignancy and other hematological conditions to assess clinical impact of identifying variants. Of detected variants, 48% facilitated or clarified diagnoses, 29% affected prognoses, and 25% had the potential to influence clinical management. Of note, OMP was essential to identifying patients with premalignant clonal states likely contributing to cytopenias. We also found that the detection of even a single variant by the OMP assay, versus 0 variants, was predictive of overall survival, independent of age, sex, or diagnosis (P = 0.03). This study demonstrates that molecular profiling of myeloid malignancies with the OMP represents a promising strategy to advance molecular diagnostics.

A DNA methylation-based liquid biopsy for triple-negative breast cancer

Here, we present a next-generation sequencing (NGS) methylation-based blood test called methylation DETEction of Circulating Tumour DNA (mDETECT) designed for the optimal detection and monitoring of metastatic triple-negative breast cancer (TNBC). Based on a highly multiplexed targeted sequencing approach, this assay incorporates features that offer superior performance and included 53 amplicons from 47 regions. Analysis of a previously characterised cohort of women with metastatic TNBC with limited quantities of plasma (<2 ml) produced an AUC of 0.92 for detection of a tumour with a sensitivity of 76% for a specificity of 100%. mDETECT_TNBC was quantitative and showed superior performance to an NGS TP53 mutation-based test carried out on the same patients and to the conventional CA15-3 biomarker. mDETECT also functioned well in serum samples from metastatic TNBC patients where it produced an AUC of 0.97 for detection of a tumour with a sensitivity of 93% for a specificity of 100%. An assay for BRCA1 promoter methylation was also incorporated into the mDETECT assay and functioned well but its clinical significance is currently unclear. Clonal Hematopoiesis of Indeterminate Potential was investigated as a source of background in control subjects but was not seen to be significant, though a link to adiposity may be relevant. The mDETECT_TNBC assay is a liquid biopsy able to quantitatively detect all TNBC cancers and has the potential to improve the management of patients with this disease.

Clonal hematopoiesis is associated with risk of severe Covid-19

Acquired 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.

Novel Mutations and Decreased Expression of the Epigenetic Regulator TET2 in Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a lethal vasculopathy. Hereditary cases are associated with germline mutations in BMPR2 and 16 other genes; however, these mutations occur in <25% of patients with idiopathic PAH and are rare in PAH associated with connective tissue diseases. Preclinical studies suggest epigenetic dysregulation, including altered DNA methylation, promotes PAH. Somatic mutations of Tet-methylcytosine-dioxygenase-2 (TET2), a key enzyme in DNA demethylation, occur in cardiovascular disease and are associated with clonal hematopoiesis, inflammation, and adverse vascular remodeling. The role of TET2 in PAH is unknown.

METHODS

To test for a role of TET2, we used a cohort of 2572 cases from the PAH Biobank. Within this cohort, gene-specific rare variant association tests were performed using 1832 unrelated European patients with PAH and 7509 non-Finnish European subjects from the Genome Aggregation Database (gnomAD) as control subjects. In an independent cohort of 140 patients, we quantified TET2 expression in peripheral blood mononuclear cells. To assess causality, we investigated hemodynamic and histological evidence of PAH in hematopoietic Tet2-knockout mice.

RESULTS

We observed an increased burden of rare, predicted deleterious germline variants in TET2 in PAH patients of European ancestry (9/1832) compared with control subjects (6/7509; relative risk=6; P=0.00067). Assessing the whole cohort, 0.39% of patients (10/2572) had 12 TET2 mutations (75% predicted germline and 25% somatic). These patients had no mutations in other PAH-related genes. Patients with TET2 mutations were older (71±7 years versus 48±19 years; P<0.0001), were more unresponsive to vasodilator challenge (0/7 versus 140/1055 [13.2%]), had lower pulmonary vascular resistance (5.2±3.1 versus 10.5±7.0 Wood units; P=0.02), and had increased inflammation (including elevation of interleukin-1β). Circulating TET2 expression did not correlate with age and was decreased in >86% of PAH patients. Tet2-knockout mice spontaneously developed PAH, adverse pulmonary vascular remodeling, and inflammation, with elevated levels of cytokines, including interleukin-1β. Long-term therapy with an antibody targeting interleukin-1β blockade resulted in regression of PAH.

CONCLUSIONS

PAH is the first human disease related to potential TET2 germline mutations. Inherited and acquired abnormalities of TET2 occur in 0.39% of PAH cases. Decreased TET2 expression is ubiquitous and has potential as a PAH biomarker.

Clonal hematopoiesis and inflammation: Partners in leukemogenesis and comorbidity

Clonal hematopoiesis (CH) of indeterminate potential (CHIP), defined as the presence of a somatic mutation in the peripheral blood at a variant allele frequency (VAF) ≥2%, affects at least 10% of individuals older than 65, but low-VAF clones can be detected in 95% of individuals older than 50. CHIP associates with a wide range of comorbidities from atherosclerosis to pulmonary disease. A growing body of evidence, primarily from studies involving Tet2-knockout and stem cell transplant models of CH, suggest that dysregulated inflammation contributes to clonal expansion and associated comorbidities. Mutant leukocytes from animal models contribute to an inflammatory milieu that may confer a selective advantage to the clone, thus perpetuating a cycle of inflammation and expansion. Although it is unclear whether inflammation or expansion sets this cycle in motion, some evidence suggests that inflammation from infections or pre-existing comorbidities initiates this cycle. The pro-inflammatory phenotypes of macrophages from mutant clones and their contributions to disease are well characterized in murine models, but have not yet been confirmed in humans. Furthermore, the roles of other cell types that can carry mutations of CHIP are not fully understood. We propose a rationale for further investigation of neutrophils, other granulocytes and T, B, and NK cells as they may play a role in CHIP-associated comorbidities. As the understanding of CH has advanced, potential interventions, especially those targeting aberrant inflammation, have been proposed. We are hopeful that as studies continue to unravel the complex links between CHIP, inflammation, and leukocyte dysfunction, CHIP-related comorbidities may be more effectively managed.

Racial and ethnic disparities in utilization of total knee arthroplasty among older women

OBJECTIVE

To evaluate racial and ethnic disparities in utilization of total knee arthroplasty (TKA) in relation to demographic, health, and socioeconomic status variables.

DESIGN

Prospective study of 102,767 Women's Health Initiative postmenopausal women initially aged 50-79, examining utilization rates of primary TKA between non-Hispanic Black/African American, non-Hispanic White, and Hispanic/Latina women (hereafter referred to as Black, White, and Hispanic). A total of 8,942 Black, 3,405 Hispanic, and 90,420 White women with linked Medicare claims data were followed until time of TKA, death, or transition from fee-for-service coverage. Absolute disparities were determined using utilization rates by racial/ethnic group and relative disparities quantified using multivariable hazards models in adjusting for age, arthritis, joint pain, mobility disability, body mass index, number of comorbidities, income, education, neighborhood socioeconomic status (SES), and geographic region.

RESULTS

TKA utilization was higher among White women (10.7/1,000 person-years) compared to Black (8.5/1,000 person-years) and Hispanic women (7.6/1,000 person-years). Among women with health indicators for TKA including diagnosis of arthritis, moderate to severe joint pain, and mobility disability, Black and Hispanic women were significantly less likely to undergo TKA after adjusting for age [Black: HR (95% confidence interval) = 0.70 (0.63-0.79); Hispanic: HR = 0.58 (0.44-0.77)]. Adjustment for SES modestly attenuated the measured disparity, but significant differences remained [Black: HR = 0.75 (0.67-0.89); Hispanic: HR = 0.65 (0.47-0.89)].

CONCLUSIONS

Compared to White women, Black and Hispanic women were significantly less likely to undergo TKA after considering need and appropriateness for TKA and SES. Further investigation into personal-level and provider-level factors that may explain these disparities is warranted.

Genomic Biomarkers to Predict Resistance to Hypomethylating Agents in Patients With Myelodysplastic Syndromes Using Artificial Intelligence

PURPOSE

We developed an unbiased framework to study the association of several mutations in predicting resistance to hypomethylating agents (HMAs) in patients with myelodysplastic syndromes (MDS), analogous to consumer and commercial recommender systems in which customers who bought products A and B are likely to buy C: patients who have a mutation in gene A and gene B are likely to respond or not respond to HMAs.

METHODS

We screened a cohort of 433 patients with MDS who received HMAs for the presence of common myeloid mutations in 29 genes that were obtained before the patients started therapy. The association between mutations and response was evaluated by the Apriori market basket analysis algorithm. Rules with the highest confidence (confidence that the association exists) and the highest lift (strength of the association) were chosen. We validated our biomarkers in samples from patients enrolled in the S1117 trial.

RESULTS

Among 433 patients, 193 (45%) received azacitidine, 176 (40%) received decitabine, and 64 (15%) received HMA alone or in combination. The median age was 70 years (range, 31 to 100 years), and 28% were female. The median number of mutations per sample was three (range, zero to nine), and 176 patients (41%) had three or more mutations per sample. Association rules identified several genomic combinations as being highly associated with no response. These molecular signatures were present in 30% of patients with three or more mutations/sample with an accuracy rate of 87% in the training cohort and 93% in the validation cohort.

CONCLUSION

Genomic biomarkers can identify, with high accuracy, approximately one third of patients with MDS who will not respond to HMAs. This study highlights the importance of machine learning technologies such as the recommender system algorithm in translating genomic data into useful clinical tools.

Targeted, Amplicon-Based, Next-Generation Sequencing to Detect Age-Related Clonal Hematopoiesis

Aging hematopoietic stem cells acquire mutations that sometimes impart a selective advantage. Next-generation DNA sequencing (NGS) can be used to detect expanded peripheral blood progeny of a mutant clone, usually carrying just one cancer-driver mutation, most often in the epigenetic regulator genes, DNMT3A or TET2. This phenomenon is known as clonal hematopoiesis (CH), age-related CH (ARCH) when considering its association with age, and CH of indeterminate potential (CHIP) when the variant allele fraction (VAF) is at least 2% in peripheral leukocytes. CHIP is present in at least 10-15% of adults older than 65 years and is a risk factor for hematological neoplasms and diseases exacerbated by mutant, hyper-inflammatory, monocytes/macrophages, such as atherosclerotic cardiovascular disease. Therefore, the detection of CHIP has important clinical consequences. Herein, we present a protocol for the generation of targeted, amplicon-based, NGS libraries for ion semiconductor sequencing and CHIP detection, using Ion Torrent platforms.

The effect of age on fitness among female firefighters

Background

The physical demands of firefighting require both cardiovascular and muscular fitness, which both decline with age. While much has been published on age-related changes among male firefighters (FFs), data on female FFs are lacking.

Aims

To describe cardiorespiratory fitness (CRF) and muscular fitness in a sample of female career FFs ranging in age from 25 to 60 years and determine whether ageing affects their achievement of the current recommended professional CRF standards of 12 metabolic equivalents (METs).

Methods

Data were collected on female FFs over an 11-year period. A cross-sectional analysis using one-way analysis of variance with Bonferroni post hoc comparisons was used to compare age groups.

Results

There were 96 study participants. Maximum METs was significantly higher (P < 0.01) in the 25- to 34-year age group (14.6 ± 2.1) compared with the 35-44 age group (12.9 ± 2.0 METs) and the 45-54 age group (12.2 ± 1.8 METs, P < 0.001). While the mean values of all measured age groups met or exceeded the 12-MET profession standard, as many as one-third of FFs <45 years of age and 43% of FFs >45 years of age fell below the benchmark of 12 METs. Muscular fitness as measured by maximum number of push-ups, sit-ups and back endurance was not significantly different between age groups.

Conclusions

Fire departments should recognize and take steps to ensure all female FFs maintain CRF and muscular fitness throughout their careers.

Abstract 5434: Screen for immune-related transcriptional targets of the Hippo pathway in human breast cancer cells

The Hippo signaling pathway has recently emerged as a cellular network that is dysregulated in cancer. In breast cancer cells, aberrant activation of the Hippo transducers (and transcriptional co-activators) TAZ and YAP leads to altered expression of their downstream gene targets and endows cells with multiple “hallmarks of cancer”. While several transcriptional targets of TAZ and YAP underlying their pro-tumorigenic activity have been described (e.g. CTGF, CYR61), gene targets of TAZ and YAP that modulate immune cell behavior in the tumor microenvironment are poorly understood. We have performed a comprehensive screen for immune-related transcriptional targets of TAZ and YAP in human breast cells. We have identified many candidate genes that are potentially regulated by TAZ and YAP including the immune checkpoint molecules PD-L1 and PD-L2, the lymphocyte regulator S1PR1 and the inflammasome component NLRP3. We have further validated PD-L1 as a bona fide transcriptional target of TAZ and YAP. These findings reveal new functions for the Hippo pathway in modifying immune responses and implicate TAZ and YAP in cancer immune evasion.

Citation Format: Helena J. Janse van Rensburg, Taha Azad, Min Ling, Yawei Hao, Lori M. Minassian, Brooke Snetsinger, Prem Khanal, Michael J. Rauh, Charles H. Graham, Xiaolong Yang. Screen for immune-related transcriptional targets of the Hippo pathway in human breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5434.

The Hippo Pathway Component TAZ Promotes Immune Evasion in Human Cancer through PD-L1

The Hippo pathway component WW domain-containing transcription regulator 1 (TAZ) is a transcriptional coactivator and an oncogene in breast and lung cancer. Transcriptional targets of TAZ that modulate immune cell function in the tumor microenvironment are poorly understood. Here, we perform a comprehensive screen for immune-related genes regulated by TAZ and its paralog YAP using NanoString gene expression profiling. We identify the immune checkpoint molecule PD-L1 as a target of Hippo signaling. The upstream kinases of the Hippo pathway, mammalian STE20-like kinase 1 and 2 (MST1/2), and large tumor suppressor 1 and 2 (LATS1/2), suppress PD-L1 expression while TAZ and YAP enhance PD-L1 levels in breast and lung cancer cell lines. PD-L1 expression in cancer cell lines is determined by TAZ activity and TAZ/YAP/TEAD increase PD-L1 promoter activity. Critically, TAZ-induced PD-L1 upregulation in human cancer cells is sufficient to inhibit T-cell function. The relationship between TAZ and PD-L1 is not conserved in multiple mouse cell lines, likely due to differences between the human and mouse PD-L1 promoters. To explore the extent of divergence in TAZ immune-related targets between human and mouse cells, we performed a second NanoString screen using mouse cell lines. We show that many targets of TAZ may be differentially regulated between these species. These findings highlight the role of Hippo signaling in modifying human/murine physiologic/pathologic immune responses and provide evidence implicating TAZ in human cancer immune evasion.Significance: Human-specific activation of PD-L1 by a novel Hippo signaling pathway in cancer immune evasion may have a significant impact on research in immunotherapy. Cancer Res; 78(6); 1457-70. ©2018 AACR.

Overexpression of Arginase 1 is linked to DNMT3A and TET2 mutations in lower-grade myelodysplastic syndromes and chronic myelomonocytic leukemia

Immune dysregulation is a common feature of myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML), particularly in early stages. However, the genetic basis remains poorly understood. We recently reported that macrophages from mice deficient in tet methylcytosine dioxygenase 2 (Tet2), a model of MDS/CMML, are hyperinflammatory and have increased expression of arginase 1 (Arg1). In macrophages and myeloid derived suppressor cells (MDSCs) expression of Arg1 contributes to T-cell suppression and immune evasion by L-arginine depletion, in the setting of chronic inflammation and cancer. Since human MDS and CMML are driven by TET2 mutations and associated with chronic inflammation, we hypothesized that arginase enzymatic activity and ARG1 expression would be increased in human MDS/CMML bone marrow. Elevated arginase activity was observed in bone marrow mononuclear cells of MDS and CMML patients with lower-grade features. Immunohistochemical studies confirmed that myelomonocytic cells overexpress ARG1. Additionally, mutations in the epigenetic regulators TET2 and DNMT3A corresponded to high ARG1 expression and activity. These findings suggest ARG1 is a biomarker of immune dysregulation in early MDS and CMML. Recent murine findings have implicated Tet2 and Dnmt3a in regulation of innate immunity. Our study suggests similar changes may be driven by human TET2 and DNMT3A mutations.

An inflammatory environment containing TNFα favors Tet2-mutant clonal hematopoiesis

Clonal hematopoiesis of aging and indeterminate potential (ARCH or CHIP), driven mainly by mutations in DNMT3A and TET2, is an emerging public health issue, affecting at least 10-15% of adults older than 65 years. CHIP is associated with increased risks of de novo and therapy-related hematological neoplasms and serves as a reservoir for leukemic relapse. CHIP is also associated with increased all-cause mortality and risk of cardio-metabolic disease. The latter association may be explained, at least in part, by the effects of inactivating mutations in TET2 on progeny macrophages. We and others have shown recently that TET2-deficient macrophages are hyperinflammatory and this may exacerbate processes such as atherosclerosis. We postulated an inflammatory state associated with TET2 inactivation and/or unhealthy aging may also favor TET2-mutant hematopoietic stem and progenitor cell (HSPC) expansion. Herein, we demonstrate a clonogenic advantage for Tet2-knockout murine and TET2-mutant human HSPCs in an in vitro environment that contains the proinflammatory cytokine tumor necrosis factor-alpha (TNFα). This phenotype emerges on chronic TNFα exposure and is associated with myeloid skewing and resistance to apoptosis. To our knowledge, this is the first evidence to suggest that TET2 mutations promote clonal dominance with aging by conferring TNFα resistance to sensitive bone marrow progenitors while also propagating such an inflammatory environment. Normalizing the immune environment may present a novel strategy to control or eradicate mutant CHIP clones.

Tet2 restrains inflammatory gene expression in macrophages

Tet methylcytosine dioxygenase 2 (TET2) is one of the earliest and most frequently mutated genes in clonal hematopoiesis of indeterminate potential (CHIP) and myeloid cancers, including myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML). TET2 catalyzes the oxidation of 5-methylcytosine to 5-hydroxymethylcytosine, leading to DNA demethylation, and also affects transcription by recruiting histone modifiers. Inactivating TET2 mutations cause epigenetic dysregulation, clonal hematopoietic stem cell (HSC) dominance, and monocytic lineage skewing. Here, we found that Tet2 was the most highly expressed Tet enzyme in murine macrophage (MΦ) differentiation. Tet2 transcription was further induced by lipopolysaccharide (LPS), but not interleukin (IL)-4, stimulation, potentially in a nuclear factor κβ-dependent manner. Tet2 loss did not affect early LPS gene responses in vitro, but increased Il-1b, Il-6, and Arginase 1 (Arg1) mRNA expression at later stages of stimulation in bone-marrow-derived MΦs (BMMΦs). Tet2-deficient peritoneal MΦs, however, demonstrated profound, constitutive expression of LPS-induced genes associated with an inflammatory state in vivo. In contrast, Tet2 deficiency did not affect alternative MΦ gene expression significantly in response to IL-4. These results suggested impaired resolution of inflammation in the absence of Tet2 both in vitro and in vivo. For the first time, we also detected TET2 mutations in BMMΦs from MDS and CMML patients and assayed their effects on LPS responses, including their potential influence on human IL-6 expression. Our results show that Tet2 restrains inflammation in murine MΦs and mice, raising the possibility that loss of TET2 function in MΦs may alter the immune environment in the large elderly population with TET2-mutant CHIP and in TET2-mutant myeloid cancer patients.

Randomized Phase II Study of Azacitidine Alone or in Combination With Lenalidomide or With Vorinostat in Higher-Risk Myelodysplastic Syndromes and Chronic Myelomonocytic Leukemia: North American Intergroup Study SWOG S1117

Purpose Azacitidine is standard, first-line therapy in higher-risk myelodysplastic syndromes (MDS). Whether azacitidine-based combinations with lenalidomide or vorinostat produce superior overall response rates (ORRs) to azacitidine is not known. Patients and Methods North American Intergroup Study S1117 is a phase II/III trial that randomly assigned patients with higher-risk MDS and chronic myelomonocytic leukemia (CMML) 1:1:1 to azacitidine (75 mg/m²/day on days 1 to 7 of a 28-day cycle); azacitidine plus lenalidomide (10 mg/day on days 1 to 21); or azacitidine plus vorinostat (300 mg twice daily on days 3 to 9). The primary phase II end point was improved ORR. Results Of 277 patients from 90 centers, 92 received azacitidine, 93 received azacitidine plus lenalidomide, and 92 received azacitidine plus vorinostat. Median age was 70 years (range, 28 to 93 years), 85 patients (31%) were female, and 53 patients (19%) had CMML. Serious adverse events were similar across arms, although combination-arm patients were more likely to undergo nonprotocol-defined dose modifications ( P < .001).With a median follow-up of 23 months (range, 1 to 43 months), the ORR was 38% for patients receiving azacitidine, 49% for azacitidine plus lenalidomide ( P = .14 v azacitidine), and 27% for azacitidine plus vorinostat ( P = .16 v azacitidine). For patients with CMML, ORR was higher for azacitidine plus lenalidomide versus azacitidine (68% v 28%, P = .02) but similar for all arms across cytogenetic subgroups, as was remission duration and overall survival. ORR was higher with mutations in DNMT3A and lower for SRSF2, whereas ORR duration improved with fewer mutations. Lenalidomide dose reduction was associated with worse overall survival (hazard ratio, 1.30; P = .05). Conclusion Patients with higher-risk MDS treated with azacitidine-based combinations had similar ORR to azacitidine monotherapy, although patients with CMML benefitted from azacitidine plus lenalidomide. The efficacy of combination regimens may have been affected by dose modifications.

A multistate framework for the analysis of subsequent injury in sport (M-FASIS)

Physical activity is beneficial for many aspects of health but is associated with a risk of injury. Studies that assess causal risk factors of injury and reinjury provide valuable information to help develop and improve injury prevention programs. However, the underlying assumptions of analytical approaches often used to estimate causal factors in injury and subsequent injury research are often violated. This means that ineffective or even harmful interventions could be proposed because the underlying analyses produced unreliable or invalid causal effect estimates. We describe an adapted version of the multistate framework [multistate framework for the analysis of subsequent injury in sport (M-FASIS)] that makes investigator choices more transparent with respect to outcome and healing time. In addition, M-FASIS incorporates all previous sport injury analytical frameworks and accounts for injuries or conditions that heal or do not heal to 100%, acute and overuse injuries, illnesses, and competing event outcomes.

Microangiopathic hemolytic anemia and leukoerythroblastic blood film heralding bone marrow metastatic gastroesophageal adenocarcinoma

Despite modern technological advancements in laboratory hematology, the blood film remains an important diagnostic aid. Herein, we report the case of a patient with a history of gastric cancer, who presented seven years following apparently successful surgery and adjuvant chemo-radio-therapy, with blood film findings of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and leukoerythroblastosis (LEB). Although mimicking features of thrombotic thrombocytopenic purpura (TTP), subsequent bone marrow examination instead revealed an association with occult recurrence of necrotic, metastatic gastric adenocarcinoma. This case report and literature review highlight these rare, but important, hematological manifestations of gastric cancer, and the importance of astute laboratory and bone marrow investigations in preventing delays in appropriate treatment of the underlying malignancy.

The role of SHIP in macrophages

The SH2-containing inositol-5'-phosphatase, SHIP, represses the proliferation, survival, and activation of hematopoietic cells, in large part by translocating to membranes following extracellular stimulation and hydrolysing the phosphatidylinositol-3-kinase (PI3K)-generated second messenger PI-3,4,5-P3 (PIP3) to PI-3,4-P2. SHIP-/- mice have, as a result, an increased number of monocyte/macrophages because their progenitors display enhanced survival and proliferation, as well as more rapid differentiation. Interestingly, SHIP-/- mice do not display lipopolysaccharide (LPS)- or CpG oligonucleotide-induced tolerance because this blunting of inflammatory mediator production is contingent upon LPS- and CpG-induced upregulation of SHIP in their macrophages and mast cells. This upregulation is mediated via the production of autocrine-acting TGFbeta which is induced via the MyD88-dependent pathway. The increased levels of SHIP then inhibit both MyD88-dependent and independent signaling. Intriguingly, SHIP-/- peritoneal and alveolar macrophages produce less nitric oxide (NO) than wild-type macrophages because they have constitutively high arginase I levels and this enzyme competes with inducible nitric oxide synthase (iNOS) for the substrate L-arginine. It is likely that, in the face of chronically elevated PIP3 levels in their myeloid progenitors, SHIP-/- mice display a skewed development away from M1 (killer) macrophages towards M2 (healing) macrophages. This suggests that SHIP plays a critical role in programming macrophages.

SHIP represses the generation of alternatively activated macrophages

We recently reported that SHIP restrains LPS-induced classical (M1) activation of in vitro differentiated, bone marrow-derived macrophages (BMMPhis) and that SHIP upregulation is essential for endotoxin tolerance. Herein, we show that in vivo differentiated SHIP-/- peritoneal (PMPhis) and alveolar (AMPhis) macrophages, unlike their wild-type counterparts, are profoundly M2 skewed (alternatively activated), possessing constitutively high arginase I (ArgI) and Ym1 levels and impaired LPS-induced NO production. Consistent with this, SHIP-/- mice display M2-mediated lung pathology and enhanced tumor implant growth. Interestingly, BMMPhis from SHIP-/- mice do not display this M2 phenotype unless exposed to TGFbeta within normal mouse plasma (MP) during in vitro differentiation. Our results suggest that SHIP functions in vivo to repress M2 skewing and that macrophage polarization can occur during differentiation in response to TGFbeta if progenitors have elevated PIP3.

The role of SHIP1 in macrophage programming and activation

The SHIP1 (SH2-containing inositol-5′-phosphatase 1) acts as a negative regulator of proliferation, survival and end cell activation in haemopoietic cells. It does so, at least in part, by translocating to membranes after extracellular stimulation and hydrolysing the phosphoinositide 3-kinase-generated second messenger, PtdIns(3,4,5)P3 to PtdIns(3,4)P2. SHIP1−/− mice have, as a result, an increased number of neutrophils and monocyte/macrophages because their progenitors display enhanced survival and proliferation. These mice also suffer from osteoporosis because of an increased number of hyperactive osteoclasts and a significant neutrophil infiltration of the lungs. Interestingly, SHIP1−/− mice do not display endotoxin tolerance and we have found that lipopolysaccharide-induced endotoxin tolerance is contingent on up-regulating SHIP1, through the production of autocrine-acting transforming growth factor-β, in bone-marrow-derived macrophages and mast cells. Intriguingly, unlike bone-marrow-derived macrophages, SHIP1−/− peritoneal and alveolar macrophages produce 10-fold less NO than wild-type macrophages because these in vivo-generated macrophages have very high arginase I levels and this enzyme competes with inducible nitric oxide synthase for the substrate L-arginine. It is probable that, in the face of chronically increased PtdIns(3,4,5)P3 levels in their myeloid progenitors, SHIP1−/− mice display a skewed development away from M1 (killer) macrophages (which have high inducible nitric oxide synthase levels and produce NO to kill microorganisms and tumour cells), towards M2 (healing) macrophages (which have high arginase levels and produce ornithine to promote host-cell growth and collagen formation). This skewing probably occurs to avoid septic shock and suggests that the phosphoinositide 3-kinase pathway plays a critical role in programming macrophages.

LPS-induced upregulation of SHIP is essential for endotoxin tolerance

An initial exposure to lipopolysaccharide (LPS) induces a transient state of hyporesponsiveness to a subsequent challenge with LPS. The mechanism underlying this phenomenon, termed endotoxin tolerance, remains poorly understood despite a recent resurgence of interest in this area. We demonstrate herein that SHIP(-/-) bone marrow-derived macrophages (BMmphis) and mast cells (BMMCs) do not display endotoxin tolerance. Moreover, an initial LPS treatment of wild-type BMmphis or BMMCs increases the level of SHIP, but not SHIP2 or PTEN, and this increase is critical for the hyporesponsiveness to subsequent LPS stimulation. Interestingly, this increase in SHIP protein is mediated by the LPS-induced production of autocrine-acting TGFbeta and neutralizing antibodies to TGFbeta block LPS-induced endotoxin tolerance. In vivo studies with SHIP(+/+) and SHIP(-/-) mice confirm these in vitro findings and show a correlation between the duration of endotoxin tolerance and elevated SHIP levels.

The role of SHIP in cytokine-induced signaling

The phosphatidylinositol (PI)-3 kinase (PI3K) pathway plays a central role in regulating many biological processes via the generation of the key second messenger PI-3,4,5-trisphosphate (PI-3,4,5-P3). This membrane-associated phospholipid, which is rapidly, albeit transiently, synthesized from PI-4,5-P2 by PI3K in response to a diverse array of extracellular stimuli, attracts pleckstrin homology (PH) domain-containing proteins to membranes to mediate its many effects. To ensure that the activation of this pathway is appropriately suppressed/terminated, the ubiquitously expressed tumor suppressor PTEN hydrolyzes PI-3,4,5-P3 back to PI-4,5-P2 while the 145-kDa hemopoietic-restricted SH2-containing inositol 5'- phosphatase, SHIP (also known as SHIP1), the 104-kDa stem cell-restricted SHIP (sSHIP) and the more widely expressed 150-kDa SHIP2 hydrolyze PI-3,4,5-P3 to PI-3,4-P2. In this review we will concentrate on the properties of the three SHIPs, with special emphasis being placed on the role that SHIP plays in cytokine-induced signaling.

SHIP, SHIP2, and PTEN activities are regulated in vivo by modulation of their protein levels: SHIP is up-regulated in macrophages and mast cells by lipopolysaccharide

The phosphatidylinositol-3 kinase (PI3K) pathway plays a central role in regulating numerous biologic processes, including survival, adhesion, migration, metabolic activity, proliferation, differentiation, and end cell activation through the generation of the potent second messenger PI-3,4,5-trisphosphate (PI-3,4,5-P(3)). To ensure that activation of this pathway is appropriately suppressed/terminated, the ubiquitously expressed 54-kDa tumor suppressor PTEN hydrolyzes PI-3,4,5-P(3) to PI-4,5-P(2), whereas the 145-kDa hematopoietic-restricted SH2-containing inositol 5'-phosphatase SHIP (also known as SHIP1), the 104-kDa stem cell-restricted SHIP sSHIP, and the more widely expressed 150-kDa SHIP2 break it down to PI-3,4-P(2). In this review, we focus on the properties of these phospholipid phosphatases and summarize recent data showing that the activities of these negative regulators often are modulated by simply altering their protein levels. We also highlight the critical role that SHIP plays in lipopolysaccharide-induced macrophage activation and in endotoxin tolerance.

Role of Src homology 2-containing-inositol 5'-phosphatase (SHIP) in mast cells and macrophages

The haemopoietic-restricted Src homology 2-containing inositol 5'-phosphatase (SHIP) acts as a negative regulator of myeloid cell proliferation, survival and end-cell activation. It does so, at least in part, by hydrolysing the phosphoinositide 3-kinase (PI3K)-generated second messenger, PtdIns(3,4,5) P (3) (PI-3,4,5-P(3)) to PtdIns(3,4) P (2). As a result, the myeloid progenitors in SHIP-knockout mice display enhanced survival and proliferation and the mice have increased numbers of neutrophils and monocytes/macrophages. Interestingly, although SHIP is not required for mast cell or macrophage development, it restrains their differentiation since progenitors from SHIP(-/-) mice differentiate into mature mast cells and macrophages significantly faster than their wild-type counterparts. This could suggest that elevated PI-3,4,5-P(3) levels accelerate myeloid differentiation. In bone-marrow-derived mast cells, SHIP prevents degranulation by IgE alone, restrains IgE-antigen-induced degranulation and limits the production of inflammatory cytokines. On the other hand, in peritoneal macrophages, SHIP is a positive regulator of NO production, since SHIP(-/-) peritoneal macrophages produce 5-10-fold less NO than their wild-type counterparts, even though they show greater lipopolysaccharide/interferon-gamma-induced nuclear factor kappa B activation and more rapid inducible NO synthase (iNOS) generation. This is a result of 10-fold higher levels of arginase I in the SHIP(-/-) macrophages, which redirects the iNOS substrate, L-arginine, from NO to ornithine production. This suggests that the chronically elevated PI-3,4,5-P(3) levels in SHIP(-/-) mice may convert M1 (killing) macrophages, which produce NO to kill micro-organisms and tumour cells, into M2 (healing) macrophages, which produce ornithine to promote host cell growth and fibrosis.