Galectin-1 is associated with hematopoietic cell engraftment in murine MHC-mismatched allotransplantation.

Haploidentical hematopoietic cell transplantation (haplo-HCT) is associated with an increased risk of allograft rejection. Here, we employed a major histocompatibility complex (MHC)-mismatched allogeneic HCT (allo-HCT) murine model to better understand the role of Gal-1 in immune tolerance. Transplanted mice were classified into either rejected or engrafted based on donor chimerism levels. We noted significantly higher frequencies of CD4+ T cells, CD8+ T cells, natural killer cells, IFN-γ and TNF-α producing CD4+ T cells, and IFN-γ producing dendritic cells and macrophages in rejected mice. Conversely, we found significantly increased frequencies of regulatory T cells (Tregs), predominantly Helios+, IL-10-producing CD4+ T cells, type 1 regulatory (Tr1) cells, and the proportion of Tr1+Gal-1+ cells in engrafted mice. Further, Gal-1 specific blockade in Tregs reduced suppression of effector T cells in engrafted mice. Lastly, effector T cells from engrafted mice were more prone to undergo apoptosis. Collectively, we have shown that Gal-1 may favor HSC engraftment in an MHC-mismatched murine model. Our results demonstrate that Gal-1-expressing Tregs, especially at earlier time points post-transplant, are associated with inducing immune tolerance and stable mixed chimerism after HCT.

Pulmonary Function after Nonmyeloablative Hematopoietic Cell Transplant for Sickle Cell Disease.

Rationale: Sickle cell disease (SCD) is a monogenetic condition with recurring vasoocclusive events causing lifelong pulmonary morbidity and mortality. There is increasing access to curative therapies, such as hematopoietic cell transplant (HCT), for people living with SCD. However, more information on pulmonary function in adults with SCD after HCT is needed to best guide decisions for HCT and post-HCT care. Objectives: To test the hypothesis that forced expiratory volume in 1 second (FEV1) and other pulmonary function testing (PFT) parameters remain stable 3 years after HCT. Methods: People living with SCD undergoing nonmyeloablative HCT in a prospective cohort at the NIH Clinical Center from 2004 to 2019 were evaluated for enrollment. Global Lung Function Initiative reference equations and descriptive statistics were calculated before HCT and annually for 3 years. Six-minute-walk distance (6MWD) testing was performed. Generalized estimating equations were employed to evaluate interindividual changes in PFT parameters and 6MWD. Results: Of 97 patients with SCD undergoing HCT, 41 (42%) were female with median (25th, 75th percentile) age 31.8 (24.8, 38.0) years. Each year of measurement included the following numbers of subjects available for analysis with PFTs: baseline (n = 97), Year 1 (n = 91), Year 2 (n = 72), and Year 3 (n = 55); and the following numbers of subjects available for analysis with 6MWD: baseline (n = 79), Year 1 (n = 73), Year 2 (n = 57), and Year 3 (n = 41). Pre-HCT FEV1 was median (25th, 75th percentile) 68.3% (61.3%, 80.3%) and 69.2% (60.8%, 77.7%) 3 years after HCT, and pre-HCT diffusing capacity of the lung for carbon monoxide (DlCO) was 60.5% (53.0%, 66.3%) and 64.6% (55.1%, 73.4%) 3 years after HCT. Generalized estimating equations estimated that DlCO percent predicted increased significantly by 3.7% (95% confidence interval, 1.0%, 6.3%), and the 6MWD significantly increased by 25.9 (6.6, 45.2) meters 3 years after HCT, whereas there was no significant change in percent predicted FEV1 or FVC compared with before HCT. Conclusions: Overall, PFT results remained stable and there was an improvement in DlCO and 6MWD in this predominantly adult cohort undergoing nonmyeloablative HCT for SCD. Allogeneic HCT for SCD may cease the cycle of vasoocclusive pulmonary injury and prevent continued damage. Multicenter studies are needed to evaluate the long-term lung health effects of HCT for SCD in adults and children.

Proteomic analyses of urinary exosomes identify novel potential biomarkers for early diagnosis of sickle cell nephropathy, a sex-based study.

Sickle cell nephropathy (SCN) is a leading cause of morbidity and mortality in sickle cell disease (SCD). Early intervention is crucial for mitigating its effects. However, current diagnostic methods rely on generic tests and may not detect SCN until irreversible renal damage occurs. Therefore, specific biomarkers for early diagnosis of SCN are needed. Urinary exosomes, membrane-bound vesicles secreted by renal podocytes and epithelial cells, contain both common and cell type-specific membrane and cytosolic proteins, reflecting the physiologic and pathophysiologic states of the kidney. Using proteomics, we analyzed the proteomes of urinary exosomes from humanized SCD mice at 2 months (without albuminuria) and 4 months (with albuminuria) of age. Excretion of 164 proteins were significantly increased and 176 proteins was significantly decreased in the exosomes when mice developed albuminuria. Based on the relevance to SCD, chronic kidney disease and Western blot confirmation in mice, we analyzed protein abundance of heparanase, cathepsin C, α2-macroglobulin and sarcoplasmic endoplasmic Ca2+ ATPase-3 (SERCA3) in the urinary exosomes and urine of 18 SCD subjects without albuminuria and 12 subjects with albuminuria using Western blot analyses. Both male and female subjects increased or tended to increase the excretion of these proteins in their urinary exosomes upon developing albuminuria, but female subjects demonstrated stronger correlations between the excretion of these proteins and urine albumin creatinine ratio (UACR) compared to male subjects. In contrast, exosomal excretion of Tamm-Horsfall protein, ß-actin and SHP-1 was independent of albuminuria. These findings provide a foundation for a time-course study to determine whether increases in the levels of these proteins precede the onset of albuminuria in patients, which will help determine the potential of these proteins as biomarkers for early detection of SCN.

TP53 mutation screening for patients at risk of myeloid malignancy.

There is increasing recognition of the risk of developing therapy-related myeloid malignancy, including after cellular therapy. While retrospective studies have implicated pre-existing TP53 mutated hematopoietic clones as a common causative mechanism, no prospective screening to identify those patients at greatest risk is currently possible. We demonstrate that ultradeep DNA-sequencing prior to therapy may be used for discovery of TP53 mutations that are subsequently associated with malignancy.

Low dose post-transplant cyclophosphamide and sirolimus induce mixed chimerism with CTLA4-Ig or lymphocyte depletion in an MHC-mismatched murine allotransplantation model.

Allogeneic hematopoietic cell transplantation (allo-HCT) offers a curative option for patients with certain non-malignant hematological diseases. High-dose post-transplant cyclophosphamide (PT-Cy) (200 mg/kg) and sirolimus (3 mg/kg), (HiC) synergistically induce stable mixed chimerism. Further, sirolimus and cytotoxic T lymphocyte-associated antigen-4 immunoglobulin (CTLA4-Ig), also known as Abatacept (Aba), promote immune tolerance and allograft survival. Here, in a major histocompatibility complex (MHC)-mismatched allo-HCT murine model, we combined Aba and/or T-cell depleting anti-Thy1.2 (Thy) with a lower dose of PT-Cy (50 mg/kg) and Sirolimus (3 mg/kg), (LoC). While mice in the LoC group showed graft rejection, the addition of Thy to LoC induced similar donor chimerism levels when compared to the HiC group. However, the addition of Aba to LoC led to graft acceptance only in younger mice. When Thy was added to the LoC+Aba setting, graft acceptance was restored in both age groups. Engrafted groups displayed significantly reduced frequencies of recipient-specific interferon-γ-producing T cells as well as an increased frequency in regulatory T cells (Tregs) except in the LoC+Aba group. Splenocytes from engrafted mice showed no proliferation upon restimulation with Balb/c stimulators. Collectively, in combination with Aba or Thy, LoC may be considered to reduce graft rejection in patients who undergo allo-HCT.

Improvement in Cardiac Morphology Demonstrated by Cardiac Magnetic Resonance Imaging and Echocardiography after Haploidentical Hematopoietic Cell Transplantation in Adults with Sickle Cell Disease.

Cardiopulmonary complications account for approximately 40% of deaths in patients with sickle cell disease (SCD). Diffuse myocardial fibrosis, elevated tricuspid regurgitant jet velocity (TRV) and iron overload are all associated with early mortality. Although HLA-matched sibling hematopoietic cell transplantation (HCT) offers a potential cure, less than 20% of patients have a suitable donor. Haploidentical HCT allows for an increased donor pool and has recently demonstrated improved safety and efficacy. Our group has reported improved cardiac morphology via echocardiography at 1 year after HCT. Here we describe the first use of cardiac magnetic resonance imaging (CMR), the gold standard for measuring volume, mass, and ventricular function, to evaluate changes in cardiac morphology post-HCT in adults with SCD. We analyzed baseline and 1-year data from 12 adults with SCD who underwent nonmyeloablative haploidentical peripheral blood HCT at the National Institutes of Health. Patients underwent noncontrast CMR at 3 T, echocardiography, and laboratory studies. At 1 year after HCT, patients showed marked improvement in cardiac chamber morphology by CMR, including left ventricular (LV) mass (70.2 to 60.1 g/m2; P = .02) and volume (114.5 to 90.6 mL/m2; P = .001). Furthermore, mean TRV normalized by 1 year, suggesting that HCT may offer a survival benefit. Fewer patients had pathologically prolonged native myocardial T1 times, an indirect marker of myocardial fibrosis at 1 year; these data showed a trend toward significance. In this small sample, CMR was very sensitive in detecting cardiac mass and volume changes after HCT and provided complementary information to echocardiography. Notably, post-HCT improvement in cardiac parameters can be attributed only in part to the resolution of anemia; further studies are needed to determine the roles of myocardial fibrosis reversal, improved blood flow, and survival impact after HCT for SCD.

Thyroid and Adrenal Dysfunction in Hemoglobinopathies Before and After Allogeneic Hematopoietic Cell Transplant.

Purpose: To determine the rate and clinical characteristics associated with abnormal thyroid and adrenal function in recipients of nonmyeloablative hematopoietic cell transplantation (HCT) for sickle cell disease (SCD) and beta-thalassemia. Methods: We retrospectively reviewed patients who enrolled in 4 nonmyeloablative HCT regimens with alemtuzumab and total body irradiation (TBI). Baseline and annual post-HCT data were compared, which included age, sex, sickle phenotype, thyroid panel (total T3, free T4, thyroid stimulating hormone, antithyroid antibodies), cortisol level, ACTH stimulation testing, ferritin, medications, and other relevant medical history. Results: Among 43 patients in haploidentical transplant and 84 patients in the matched related donor protocols with mostly SCD, the rate of any thyroid disorder pre-HCT was 3.1% (all subclinical hypothyroidism) and post-HCT was 29% (10 hypothyroidism, 4 Grave's disease, and 22 subclinical hypothyroidism). Ninety-two (72%) patients had ferritin >1000 ng/dL, of which 33 patients (35.8%) had thyroid dysfunction. Iron overload was noted in 6 of 10 patients with hypothyroidism and 12 of 22 patients with subclinical hypothyroidism.Sixty-one percent were on narcotics for pain control. With respect to adrenal insufficiency (AI) pre-HCT, 2 patients were maintained on corticosteroids for underlying rheumatologic disorder and 8 had AI diagnosed during pre-HCT ACTH stimulation testing (total 10, 7.9%). Post-HCT, an additional 4 (3%) developed AI from corticosteroid use for acute graft vs host disease, Evans syndrome, or hemolytic anemia. Conclusion: Although iron overload was common in SCD, thyroid dysfunction pre-HCT related to excess iron was less common. Exposure to alemtuzumab or TBI increased the rates of thyroid dysfunction post-HCT. In contrast, AI was more common pre-HCT, but no risk factor was identified. AI post-HCT was infrequent and associated with corticosteroid use for HCT-related complications.

Longitudinal neurocognitive effects of nonmyeloablative hematopoietic stem cell transplant among older adolescents and adults with sickle cell disease: A description and comparison with sibling donors.

Sickle cell disease (SCD) is associated with increased risk of neurocognitive deficits. However, whether functioning changes following nonmyeloablative hematopoietic stem cell transplant (HSCT) remains unclear. This study aimed to examine changes in neuropsychological functioning pre- to post-transplant among patients with SCD and compare patients and siblings. Adults with SCD (n = 47; Mage = 31.8 ± 8.9) and their sibling stem cell donors (n = 22; Mage = 30.5± 9.2) enrolled on a nonmyeloablative HCST protocol completed cognitive and patient-reported outcome assessments at baseline and 12 months post-transplant. Path analyses were used to assess associations between pre-transplant variables and sibling/patient group status and post-transplant function. Mean patient cognitive scores were average at both timepoints. Patient processing speed and somatic complaints improved from baseline to follow-up. Baseline performance predicted follow-up performance across cognitive variables; patient/sibling status predicted follow-up performance on some processing speed measures. Results suggest that patients with SCD demonstrate slower processing speed than siblings. Processing speed increased pre- to post-HSCT among patients and siblings, and on some measures patients demonstrated greater improvement. Thus, HSCT may improve processing speed in patients, although further confirmation is needed. Findings provide promising evidence that neurocognitive functioning remains stable without detrimental effects from pre- to 12-months post nonmyeloablative HSCT in individuals with SCD.

Co-expression of Foxp3 and Helios facilitates the identification of human T regulatory cells in health and disease.

Foxp3 is regarded as the major transcription factor for T regulatory (Treg) cells and expression of Foxp3 is used to identify and quantitate Treg cells in mouse models. However, several studies have demonstrated that human CD4+ T conventional (Tconv) cells activated in vitro by T cell receptor (TCR) stimulation can express Foxp3. This observation has raised doubt as to the suitability of Foxp3 as a Treg marker in man. Helios, a member of the Ikaros gene family, has been shown to be expressed by 80-90% of human Foxp3+ Treg cells and can potentially serve as a marker of human Treg. Here, we confirm that Foxp3 expression is readily upregulated by Tconv upon TCR stimulation in vitro, while Helios expression is not altered. More importantly, we show that Foxp3 expression is not elevated by stimulation of hTconv in a humanized mouse model of graft versus host disease (GVHD) and in patients with a wide variety of acute and chronic inflammatory diseases including sickle cell disease, acute and chronic GVHD, systemic lupus erythematosus, as well as critical COVID-19. In all patients studied, an excellent correlation was observed between the percentage of CD4+ T cells expressing Foxp3 and the percentage expressing Helios. Taken together, these studies demonstrate that Foxp3 is not induced upon Tconv cell activation in vivo and that Foxp3 expression alone can be used to quantitate Treg cells in humans. Nevertheless, the combined use of Foxp3 and Helios expression provides a more reliable approach for the characterization of Treg in humans.

Secondary Neoplasms After Hematopoietic Cell Transplant for Sickle Cell Disease.

PURPOSE: To report the incidence and risk factors for secondary neoplasm after transplantation for sickle cell disease. METHODS: Included are 1,096 transplants for sickle cell disease between 1991 and 2016. There were 22 secondary neoplasms. Types included leukemia/myelodysplastic syndrome (MDS; n = 15) and solid tumor (n = 7). Fine-Gray regression models examined for risk factors for leukemia/MDS and any secondary neoplasm. RESULTS: The 10-year incidence of leukemia/MDS was 1.7% (95% CI, 0.90 to 2.9) and of any secondary neoplasm was 2.4% (95% CI, 1.4 to 3.8). After adjusting for other risk factors, risks for leukemia/MDS (hazard ratio, 22.69; 95% CI, 4.34 to 118.66; P = .0002) or any secondary neoplasm (hazard ratio, 7.78; 95% CI, 2.20 to 27.53; P = .0015) were higher with low-intensity (nonmyeloablative) regimens compared with more intense regimens. All low-intensity regimens included total-body irradiation (TBI 300 or 400 cGy with alemtuzumab, TBI 300 or 400 cGy with cyclophosphamide, TBI 200, 300, or 400 cGy with cyclophosphamide and fludarabine, or TBI 200 cGy with fludarabine). None of the patients receiving myeloablative and only 23% of those receiving reduced-intensity regimens received TBI. CONCLUSION: Low-intensity regimens rely on tolerance induction and establishment of mixed-donor chimerism. Persistence of host cells exposed to low-dose radiation triggering myeloid malignancy is one plausible etiology. Pre-existing myeloid mutations and prior inflammation may also contribute but could not be studied using our data source. Choosing conditioning regimens likely to result in full-donor chimerism may in part mitigate the higher risk for leukemia/MDS.

Reduction in vaso-occlusive events following stem cell transplantation in patients with sickle cell disease.

Hematopoietic stem cell transplantation (HSCT) is potentially curative for patients with sickle cell disease (SCD). Patients with stable donor engraftment after allogeneic HSCT generally do not experience SCD-related complications; however, there are no published data specifically reporting the change in vaso-occlusive events (VOE) after HSCT. Data regarding the number of VOEs requiring medical attention in the 2 years before allogeneic HSCT were compared with the number of VOEs in the 2 years (0-12 months and 12-24 months) after allogeneic HSCT in patients with SCD. One-hundred sixty-three patients with SCD underwent allogeneic HSCT between 2005 and 2019. The average age at the time of HSCT was 21 years (range, 7 months - 64 years). Most patients underwent nonmyeloablative conditioning (75% [N = 123]) and had a matched sibling donor (72% [N = 118]). The mean number of VOEs was reduced from 5.6 (range, 0-52) in the 2 years before HSCT to 0.9 (range, 0-12) in the 2 years after HSCT (P < .001). Among the post-HSCT events, VOE was more frequent during the first 12 months (0.8 [range, 0-12]) than at 12 to 24 months after HSCT (0.1 [range, 0-8) (P < .001)). In patients who had graft rejection (12%, N = 20), VOEs were reduced from 6.6 (range, 0-24) before HSCT to 1.1 (range, 0-6) and 0.8 (range, 0-8) at 0 to 12 months and 12 to 24 months after HSCT, respectively (P < .001). VOEs requiring medical care were significantly reduced after allogeneic HSCT for patients with SCD. These data will inform the development of novel autologous HSCT gene therapy approaches.

Knowledge to date on secondary malignancy following hematopoietic cell transplantation for sickle cell disease.

Allogeneic hematopoietic cell transplantation, gene therapy, and gene editing offer a potential cure for sickle cell disease (SCD). Unfortunately, myelodysplastic syndrome and acute myeloid leukemia development have been higher than expected after graft rejection following nonmyeloablative conditioning and lentivirus-based gene therapy employing myeloablative busulfan for SCD. Somatic mutations discovered in 2 of 76 patients who rejected their grafts were identified at baseline at much lower levels. While a whole-genome sequencing analysis reported no difference between patients with SCD and controls, a study including whole-exome sequencing revealed a higher prevalence of clonal hematopoiesis in individuals with SCD compared with controls. Genetic risk factors for myeloid malignancy development after curative therapy for SCD are currently being explored. Once discovered, decisions could be made about whether gene therapy may be feasible vs allogeneic hematopoietic cell transplant, which results in full donor chimerism. In the meantime, care should be taken to perform a benefit/risk assessment to help patients identify the best curative approach for them. Long-term follow-up is necessary to monitor for myeloid malignancies and other adverse effects of curative therapies for SCD.

Allogeneic Transplant and Gene Therapy: Evolving Toward a Cure.

Curative therapies for sickle cell disease (SCD) include allogeneic human leukocyte antigen (HLA)- matched sibling and haploidentical hematopoietic cell transplant (HCT), gene therapy, and gene editing. However, comparative trial data that might facilitate selecting one curative therapy over another are unavailable. New strategies to decrease graft rejection and graft-versus-host disease (GVHD) risks are needed to expand haploidentical HCT. Myeloablative gene therapy and gene editing also has limitations. Herein, we review recent studies on curative therapies for SCD in the past 5 years.

Long-Term Health Effects of Curative Therapies on Heart, Lungs, and Kidneys for Individuals with Sickle Cell Disease Compared to Those with Hematologic Malignancies.

The goal of curing children and adults with sickle cell disease (SCD) is to maximize benefits and minimize intermediate and long-term adverse outcomes so that individuals can live an average life span with a high quality of life. While greater than 2000 individuals with SCD have been treated with curative therapy, systematic studies have not been performed to evaluate the long-term health effects of hematopoietic stem cell transplant (HSCT) in this population. Individuals with SCD suffer progressive heart, lung, and kidney disease prior to curative therapy. In adults, these sequalae are associated with earlier death. In comparison, individuals who undergo HSCT for cancer are heavily pretreated with chemotherapy, resulting in potential acute and chronic heart, lung, and kidney disease. The long-term health effects on the heart, lung, and kidney for children and adults undergoing HSCT for cancer have been extensively investigated. These studies provide the best available data to extrapolate the possible late health effects after curative therapy for SCD. Future research is needed to evaluate whether HSCT abates, stabilizes, or exacerbates heart, lung, kidney, and other diseases in children and adults with SCD receiving myeloablative and non-myeloablative conditioning regimens for curative therapy.

Clonal Hematopoiesis and the Risk of Hematologic Malignancies after Curative Therapies for Sickle Cell Disease.

Sickle cell disease (SCD) is associated with severe morbidity and early mortality. Two large population studies found an increased risk for leukemia in individuals with SCD. Notably, while the relative risk of leukemia development is high, the absolute risk is low in individuals with SCD who do not receive cell-based therapies. However, the risk of leukemia in SCD is high after graft rejection and with gene therapy. Clonal hematopoiesis (CH) is a well-recognized premalignant condition in the general population and in patients after high-dose myelotoxic therapies. Recent studies suggest that CH may be more common in SCD than in the general population, outside the cell-based therapy setting. Here, we review risk factors for CH and progression to leukemia in SCD. We surmise why patients with SCD are at an increased risk for CH and why leukemia incidence is unexpectedly high after graft rejection and gene therapy for SCD. Currently, we are unable to reliably assess genetic risk factors for leukemia development after curative therapies for SCD. Given our current knowledge, we recommend counseling patients about leukemia risk and discussing the importance of an individualized benefit/risk assessment that incorporates leukemia risk in patients undergoing curative therapies for SCD.