Axel Nogai

MyD88/TLR9 mediated immunopathology and gut microbiota dynamics in a novel murine model of intestinal graft-versus-host disease

Background The bacterial microflora aggravates graft-versus-host-disease (GvHD) after allogeneic stem cell transplantation, but the underlying mechanisms of manifestations of intestinal GvHD (iGvHD) in the gut remain poorly understood. Aim To analyse the gut flora composition and the impact of bacterial sensing via Toll-like receptors (TLRs) in iGvHD. Methods By mimicking clinical low-intensity conditioning regimens used in humans, a novel irradiation independent, treosulfan and cyclophosphamide-based murine allogeneic transplantation model was established. A global survey of the intestinal microflora by cultural and molecular methods was performed, the intestinal immunopathology in TLR-deficient recipient mice with iGvHD investigated and finally, the impact of anti-TLR9 treatment on iGvHD development assessed. Results The inflammatory responses in iGvHD were accompanied by gut flora shifts towards enterobacteria, enterococci and Bacteroides/Prevotella spp. Analysis of iGvHD in MyD88-/-, TRIF-/-, TLR2/4-/-, and TLR9-/- recipient mice showed that bacterial sensing via TLRs was essential for iGvHD development. Acute iGvHD was characterised by increasing numbers of apoptotic cells, proliferating cells, T cells and neutrophils within the colon. These responses were significantly reduced in MyD88-/-, TLR2/4-/-, TRIF-/- and TLR9-/- mice, as compared with wild-type controls. However, TRIF-/- and TLR2/4-/- mice were not protected from mortality, whereas TLR9-/- mice displayed increased survival rates. The important role of TLR9-mediated immunopathology was independently confirmed by significantly reduced macroscopic disease symptoms and colonic apoptosis as well as by reduced T-cell and neutrophil numbers within the colon after treatment with a synthetic inhibitory oligonucleotide. Conclusions These results emphasise the critical role of gut microbiota, innate immunity and TLR9 in iGvHD and highlight anti-TLR9 strategies as novel therapeutic options.

Multiple myeloma cells alter the senescence phenotype of bone marrow mesenchymal stromal cells under participation of the DLK1-DIO3 genomic region

BackgroundAlterations and senescence in bone marrow mesenchymal stromal cells of multiple myeloma patients (MM-BMMSCs) have become an important research focus. However the role of senescence in the pathophysiology of MM is not clear.MethodsCorrelation between senescence, cell cycle and microRNA expression of MM-BMMSCs (n = 89) was analyzed. Gene expression analysis, copy number analysis and methylation specific PCR were performed by Real-Time PCR. Furthermore, cyclin E1, cyclin D1, p16 and p21 genes were analyzed at the protein level using ELISA. Cell cycle and senescence were analyzed by FACS. MiRNA transfection was performed with miR-485-5p inhibitor and mimic followed by downstream analysis of senescence and cell cycle characteristics of MM-BMMSCs. Results were analyzed by Mann–Whitney U test, Wilcoxon signed-rank test and paired t-test depending on the experimental set up.ResultsMM-BMMSCs displayed increased senescence associated β-galactosidase activity (SA-βGalA), cell cycle arrest in S phase and overexpression of microRNAs. The overexpressed microRNAs miR-485-5p and miR-519d are located on DLK1-DIO3 and C19MC, respectively. Analyses revealed copy number accumulation and hypomethylation of both clusters. KMS12-PE myeloma cells decreased SA-βGalA and influenced cell cycle characteristics of MM-BMMSCs. MiR-485-5p was significantly decreased in co-cultured MM-BMMSCs in connection with an increased methylation of DLK1-DIO3. Modification of miR-485-5p levels using microRNA mimic or inhibitor altered senescence and cell cycle characteristics of MM-BMMSCs.ConclusionsHere, we show for the first time that MM-BMMSCs have aberrant methylation and copy number of the DLK1-DIO3 and C19MC genomic region. Furthermore, this is the first study pointing that multiple myeloma cells in vitro reduce both the senescence phenotype of MM-BMMSCs and the expression of miR-223 and miR-485-5p. Thus, it is questionable whether senescence of MM-BMMSCs plays a pathological role in active multiple myeloma or is more important when cell interaction with myeloma cells is inhibited. Furthermore, we found that MiR-485-5p, which is located on the DLK1-DIO3 cluster, seems to participate in the regulation of senescence status and cell cycle characteristics of MM-BMMSCs. Thus, further exploration of the microRNAs of DLK1-DIO3 could provide further insights into the origin of the senescence state and its reversal in MM-BMMSCs.

Multiple myeloma cells modify VEGF/IL‐6 levels and osteogenic potential of bone marrow stromal cells via Notch/miR‐223

Bone marrow mesenchymal stromal cells (BMMSCs) represent a crucial component of multiple myeloma (MM) microenvironment supporting its progression and proliferation. Recently, microRNAs have become an important point of interest for research on micro‐environmental interactions in MM with some evidence of tumor supportive roles in MM. In this study, we examined the role of miR‐223 for MM support in BMMSCs of 56 patients with MM (MM‐BMMSCs). miR‐223 expression in MM‐BMMSCs was reduced by the presence of MM cells in vitro in a cell‐contact dependent manner compared to mono‐cultured MM‐BMMSCs. Co‐cultivation of MM cells and MM‐BMMSCs induced activation of notch amongst others via jagged‐2/notch‐2 leading to increased expression of Hes1, Hey2, or Hes5 in both cell types. Cultivation of MM‐BMMSCs with increasing levels of recombinant jagged‐2 reduced miR‐223 and increased Hes1 levels in a concentration‐dependent manner. Transient reduction of miR‐223 levels increased VEGF and IL‐6 expression and secretion by MM‐BMMSCs. In addition, reduction of miR‐223 degraded the osteogenic differentiation potential of MM‐BMMSCs. Inhibition of notch signaling induced apoptosis in both MM cells and MM‐BMMSCs. Furthermore, it increased miR‐223 levels and reduced expression of VEGF and IL‐6 by both cell types. These data provide first evidence that miR‐223 participates in different MM supporting pathways in MM‐BMMSCs inlcuding regulation of cytokine secretion and expression as well as osteogenic differentiation of MM‐BMMSCs. More insights on the role of miR‐223 in MM‐BMMSCs and in cellular interactions between MM cells and MM‐BMMSCs could provide starting points for a more efficient anti‐myeloma treatment by targeting of notch signaling.

Chronic Graft versus Host Disease but not the Intensity of Conditioning has Impact on Survival after Allogeneic Hematopoietic Stem Cell Transplantation for Advanced Hematological Diseases

Background: Allogeneic hematopoietic stem cell transplantation (alloHSCT) is often performed in cases of advanced hematological diseases, but because of the associated mortality and a high risk of relapse it is life prolonging only in some patients. Patients and Methods: A retrospective multi-center analysis of 401 patients was conducted to analyze the variables associated with outcome after alloHSCT in advanced hematological diseases. The Cox proportional hazards model was used to assess the independence of overall survival (OS) and disease-free survival (DFS) from prognostic factors in a multivariate model. Results: The 5-year OS and DFS were 27.3 and 21.1% respectively. Multivariate analysis showed that the underlying malignancy had a significant influence on OS and DFS (p < 0.001 and p < 0.011, respectively), whereas development of severe acute graft versus host disease (GvHD) had a negative impact on OS (p < 0.001). Development of chronic GvHD showed a trend to a better OS (p = 0.085) and DFS (p = 0.199). No impact was seen for the intensity of conditioning. Conclusion: Development of chronic GvHD but not the conditioning regimen improved the outcome after alloHSCT for advanced malignancies, underlining the importance of immunological rather than cytotoxic effects.

A novel method to quantify and characterize leukemia-reactive natural killer cells in patients undergoing allogeneic hematopoietic stem cell transplantation following conventional or reduced-dose conditioning

The antitumor activity of natural killer (NK) cells has recently been shown to be assessable at a single-cell level via flow cytometric detection of CD107a. We used this novel method to prospectively quantify and characterize tumor-reactive NK cells in patients undergoing myeloablative or nonmyeloablative conditioning and allogeneic hematopoietic stem cell transplantation (HSCT). Degranulation of NK cells in the peripheral blood of 34 patients after HSCT (day +30, day +90) was determined by evaluating CD107a expression after coincubation of the cells with tumor targets. The percentage of degranulating NK cells was higher after nonmyeloablative conditioning than after myeloablative conditioning (P < .001), indicating a higher activation state and increased antitumor activity of NK cells after nonmyeloablative conditioning. We were able to analyze NK cell subsets separately and found that CD56bright NK cells following HSCT are functionally different from CD56bright NK cells in healthy donors, as indicated by a high percentage of degranulating NK cells in response to tumor targets in patients after HSCT. The CD107a assay is a new and feasible method to quantify and characterize tumor-reactive NK cells after HSCT. Using this method, we found that NK cells had high antitumor cytotoxic activity after nonmyeloablative conditioning, which may contribute to the effectiveness of nonmyeloablative conditioning.

Cyclophosphamide‐based stem cell mobilization in relapsed multiple myeloma patients: A subgroup analysis from the phase III trial ReLApsE

Analysis of the efficiency and toxicity of cyclophosphamide‐based stem cell mobilization in patients with relapsed multiple myeloma (RMM).

Organ siderosis and hemophagocytosis during acute graft-versus-host disease

Iron overload prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT) due to blood transfusions is associated with increased non-relapse mortality (NRM) and with low overall survival.1,2 After allo-HSCT, high iron content in liver biopsies and elevated ferritin concentrations in blood, used as a surrogate parameter for iron overload, are also related to NRM.3–6 The cellular and molecular mechanisms behind this association, however, are yet to be clarified. In particular, available data on the role of ferritin and iron metabolism during the pathophysiology of acute graft-versus-host disease (GvHD), a major contributor to NRM, are scarse. To shed light on the connection between GvHD, ferritin levels, and iron metabolism, we decided to analyse the clinical data of patients undergoing allo-HSCT as well as data from preclinical murine GvHD models.