On-demand erythrocyte disposal and iron recycling requires transient macrophages in the liver

Iron is an essential component of the erythrocyte protein hemoglobin and is crucial to oxygen transport in vertebrates. In the steady state, erythrocyte production is in equilibrium with erythrocyte removal1. In various pathophysiological conditions, however, erythrocyte life span is severely compromised, which threatens the organism with anemia and iron toxicity2,3. Here we identify an on-demand mechanism that clears erythrocytes and recycles iron. We show that Ly-6Chigh monocytes ingest stressed and senescent erythrocytes, accumulate in the liver via coordinated chemotactic cues, and differentiate to ferroportin 1 (FPN1)-expressing macrophages that can deliver iron to hepatocytes. Monocyte-derived FPN1+ Tim-4neg macrophages are transient, reside alongside embryonically-derived Tim-4high Kupffer cells, and depend on Csf1 and Nrf2. The spleen likewise recruits iron-loaded Ly-6Chigh monocytes, but these do not differentiate into iron-recycling macrophages due to the suppressive action of Csf2. Inhibiting monocyte recruitment to the liver leads to kidney and liver damage. These observations identify the liver as the primary organ supporting rapid erythrocyte removal and iron recycling and uncover a mechanism by which the body adapts to fluctuations in erythrocyte integrity

Preliminary Report for the Development of a Multiparameter Protocol for the Identification of Sinusoidal Obstruction Syndrome including Abdominal Ultrasound before and after Allogeneic Stem Cell Transplantation

Sinusoidal obstruction syndrome (SOS) is a rare complication after allogeneic hematopoietic stem cell transplantation (alloHSCT) caused by endothelial dysfunction. Previous definitions and diagnostic criteria for the presence of SOS include bilirubinemia, hepatomegaly and weight gain, but histological evaluation is still the only way to prove the diagnosis of SOS. However, biopsy remains an invasive technique and is therefore undesirable in the alloHSCT scenario. Hence, a non-invasive diagnostic strategy is critical. Besides thorough clinical assessment and laboratory values, ultrasound examination remains part of the diagnostic workflow in clinical routine. Previous studies defined sonographic abnormalities, which are associated with the occurrence of SOS, but a standardized protocol to perform reliable abdominal ultrasound has not been finally defined. In this study, we evaluated a multi-parameter protocol including laboratory values as well as ultrasound examination pre- and post-alloHSCT. The application of this protocol was feasible in clinical practice and achieved a high inter- and intra-rater reliability. In our population, no case of SOS was identifiable and, in line with previous studies, no changes known to be associated with SOS were detected by ultrasound examination in our cohort. Additionally, we investigated subgroups of patients partly fulfilling SOS diagnostic criteria analyzing correlations between the fulfilled criteria and aberrances in ultrasound measurements pre- and post-alloHSCT. Although statistical examination may be limited by a small sample size and missing SOS cases, hyperbilirubinemia, thrombocytopenia and weight gain showed only a coincidence with selected, enlarged liver dimensions in few patients. This may underline the fact that hepatomegaly occurs as an unspecific finding after alloHSCT. Our protocol, including the ultrasound examination pre- and post-alloHSCT and laboratory parameters, may help to rule out SOS early, but validation in a greater population and different transplantation centers is required to warrant broader appliance. Nevertheless, we aim to contribute to an elaborate and standardized work-flow in peri-alloHSCT patient care

Selective ABO immunoadsorption in hematopoietic stem cell transplantation with major ABO incompatibility

Objective ABO mismatch between donor and recipient occurs in 40% of allogeneic hematopoietic stem cell transplantations (HCT). Different strategies have been described to reduce isohemagglutinins (IHA) before HCT. We describe the effect of selective ABO immunoadsorption (ABO IA) on erythrocyte transfusion rate and the development of post-transplant pure red cell aplasia (ptPRCA). Methods 63 patients with major ABO incompatibility were retrospectively analyzed. Nine patients with major ABO incompatibility and high-IHA titer were treated by ABO IA before HCT. We analyzed the need for transfusion and the occurrence of ptPRCA. We compared the outcome with patients treated by other methods to reduce IHA. Results In all nine patients treated by ABO IA, IHA decreased in a median four times. PtPRCA occurred in one patient. The median number of transfusions was 8 (range: 0-36) between d0 and d100. In 25 patients with high-IHA titer without treatment or treated by other methods to reduce IHA, the need for transfusions was comparable. No difference in the incidence of ptPRCA was observed. Conclusions Selective ABO IA is a feasible, safe, and effective method to reduce IHA before HCT in major ABO incompatibility. No effect on transfusion rate or ptPRCA compared to other strategies could be observed

Fecal microbiota transfer for refractory intestinal graft-versus-host disease - Experience from two German tertiary centers

Rationale Steroid refractory graft-vs-host disease (sr-GvHD) represents a challenging complication after allogeneic hematopoietic cell transplantation (allo-HCT). Intestinal microbiota (IM) diversity and dysbiosis were identified as influencing factors for the development of acute GvHD. Fecal microbiota transfer (FMT) is hypothesized to restore IM dysbiosis, but there is limited knowledge about the significance of FMT in the treatment of sr-GvHD. Objectives We studied the effects of FMT on sr-GvHD in allo-HCT patients from two German tertiary clinical centers (n = 11 patients; period: March 2017 until July 2019). To assess safety and clinical efficacy, we analyzed clinical data pre- and post-FMT (day -14 to +30 relative to FMT). Moreover, IM were analyzed in donor samples and in a subset of patients pre- and post-FMT by 16S rRNA sequencing. Results Post-FMT, we observed no intervention-associated, systemic inflammatory responses and only minor side effects (5/11 patients: abdominal pain and transformation of peristalsis-each 3/11 and vomiting-1/11). Stool frequencies and volumes were significantly reduced [pre- vs post-FMT (d14): P < .05, respectively] as well as clear attenuation regarding both grading and staging of sr-GvHD was present upon FMT. Moreover, IM analyses revealed an increase of alpha diversity as well as a compositional shifts toward the donor post-FMT. Conclusions In our study, we observed positive effects on sr-GVHD after FMT without the occurrence of major adverse events. Although these findings are in line with published data on beneficial effects of FMT in sr-GvHD, further randomized clinical studies are urgently needed to better define the clinical validity including mode of action

The role of checkpoint blockade after allogeneic stem cell transplantation in diseases other than Hodgkin’s Lymphoma

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment option for many malignant high-risk hematological diseases. The Graft-vs.-Tumor (GvT) effect is the major hallmark of this treatment approach. However, disease relapse remains a major limitation. Boosting the GvT effect by checkpoint inhibitors (CI) is an attractive option in this desperate situation although potentially triggering Graft-vs.-Host Disease (GvHD). Early reports in patients with Hodgkin's lymphoma support the idea that CI therapy after HSCT is feasible and effective. We have retrospectively analyzed CI therapy for treatment of disease recurrence after allo-HSCT other than Hodgkin's lymphoma including 21 patients from eight German transplant centers. The median follow-up was 59 days. The overall response rate (ORR) was 43%. Patients receiving donor lymphocyte infusion (DLI) in combination with CI had superior response (ORR 80%). Severe acute GvHD grade III-IV and moderate to severe chronic GvHD were observed in 29% of all patients. Taken together, CI therapy in relapsed patients after HSCT, especially in combination with DLI, is effective but induces severe GvHD in a considerable proportion of patients. Thus, prospective trials or EBMT registry-based validation of different dosing and application schedules including immunosuppressive regimens in those patients are urgently needed

Real-world experience of CPX-351 as first-line treatment for patients with acute myeloid leukemia

To investigate the efficacy and toxicities of CPX-351 outside a clinical trial, we analyzed 188 patients (median age 65 years, range 26-80) treated for therapy-related acute myeloid leukemia (t-AML, 29%) or AML with myelodysplasia-related changes (AML-MRC, 70%). Eighty-six percent received one, 14% two induction cycles, and 10% received consolidation (representing 22% of patients with CR/CRi) with CPX-351. Following induction, CR/CRi rate was 47% including 64% of patients with available information achieving measurable residual disease (MRD) negativity (<10(-3)) as measured by flow cytometry. After a median follow-up of 9.3 months, median overall survival (OS) was 21 months and 1-year OS rate 64%. In multivariate analysis, complex karyotype predicted lower response (p = 0.0001), while pretreatment with hypomethylating agents (p = 0.02) and adverse European LeukemiaNet 2017 genetic risk (p < 0.0001) were associated with lower OS. Allogeneic hematopoietic cell transplantation (allo-HCT) was performed in 116 patients (62%) resulting in promising outcome (median survival not reached, 1-year OS 73%), especially in MRD-negative patients (p = 0.048). With 69% of patients developing grade III/IV non-hematologic toxicity following induction and a day 30-mortality of 8% the safety profile was consistent with previous findings. These real-world data confirm CPX-351 as efficient treatment for these high-risk AML patients facilitating allo-HCT in many patients with promising outcome after transplantation