Affibody-based hBCMA x CD16 dual engagers for NK cell-mediated killing of multiple myeloma cells.

We describe the development and characterization of the (to date) smallest Natural Killer (NK) cell re-directing human B Cell Maturation Antigen (hBCMA) x CD16 dual engagers for potential treatment of multiple myeloma, based on combinations of small 58 amino acid, non-immunoglobulin, affibody affinity proteins. Affibody molecules to human CD16a were selected from a combinatorial library by phage display resulting in the identification of three unique binders with affinities (KD) for CD16a in the range of 100 nM-3 µM. The affibody exhibiting the highest affinity demonstrated insensitivity towards the CD16a allotype (158F/V) and did not interfere with IgG (Fc) binding to CD16a. For the construction of hBCMA x CD16 dual engagers, different CD16a binding arms, including bi-paratopic affibody combinations, were genetically fused to a high-affinity hBCMA-specific affibody. Such 15-23 kDa dual engager constructs showed simultaneous hBCMA and CD16a binding ability and could efficiently activate resting primary NK cells and trigger specific lysis of a panel of hBCMA-positive multiple myeloma cell lines. Hence, we report a novel class of uniquely small NK cell engagers with specific binding properties and potent functional profiles.

Perturbed NK-cell homeostasis associated with disease severity in chronic neutropenia.

Neutrophils have been thought to play a critical role in terminal differentiation of NK cells. Whether this effect is direct or a consequence of global immune changes with effects on NK-cell homeostasis remains unknown. In this study, we used high-resolution flow and mass cytometry to examine NK-cell repertoires in 64 patients with neutropenia and 27 healthy age- and sex-matched donors. A subgroup of patients with chronic neutropenia showed severely disrupted NK-cell homeostasis manifesting as increased frequencies of CD56bright NK cells and a lack of mature CD56dim NK cells. These immature NK-cell repertoires were characterized by expression of the proliferation/exhaustion markers Ki-67, Tim-3, and TIGIT and displayed blunted tumor target cell responses. Systems-level immune mapping revealed that the changes in immunophenotypes were confined to NK cells, leaving T-cell differentiation intact. RNA sequencing of NK cells from these patients showed upregulation of a network of genes, including TNFSF9, CENPF, MKI67, and TOP2A, associated with apoptosis and the cell cycle, but different from the conventional CD56bright signatures. Profiling of 249 plasma proteins showed a coordinated enrichment of pathways related to apoptosis and cell turnover, which correlated with immature NK-cell repertoires. Notably, most of these patients exhibited severe-grade neutropenia, suggesting that the profoundly altered NK-cell homeostasis was connected to the severity of their underlying etiology. Hence, although our data suggest that neutrophils are dispensable for NK-cell development and differentiation, some patients displayed a specific gap in the NK repertoire, associated with poor cytotoxic function and more severe disease manifestations.

Transcriptome network analysis identifies protective role of the LXR/SREBP-1c axis in murine pulmonary fibrosis.

Pulmonary fibrosis (PF) is an intractable disorder with a poor prognosis. Although lung fibroblasts play a central role in PF, the key regulatory molecules involved in this process remain unknown. To address this issue, we performed a time-course transcriptome analysis on lung fibroblasts of bleomycin- and silica-treated murine lungs. We found gene modules whose expression kinetics were associated with the progression of PF and human idiopathic PF (IPF). Upstream analysis of a transcriptome network helped in identifying 55 hub transcription factors that were highly connected with PF-associated gene modules. Of these hubs, the expression of Srebf1 decreased in line with progression of PF and human IPF, suggesting its suppressive role in fibroblast activation. Consistently, adoptive transfer and genetic modification studies revealed that the hub transcription factor SREBP-1c suppressed PF-associated gene expression changes in lung fibroblasts and PF pathology in vivo. Moreover, therapeutic pharmacological activation of LXR, an SREBP-1c activator, suppressed the Srebf1-dependent activation of fibroblasts and progression of PF. Thus, SREBP-1c acts as a protective hub of lung fibroblast activation in PF. Collectively, the findings of the current study may prove to be valuable in the development of effective therapeutic strategies for PF.

Extracorporeal photopheresis with TC-V in Japanese patients with steroid-resistant chronic graft-versus-host disease.

There are few established therapies for chronic graft-versus-host disease (cGVHD) refractory to first-line treatment with steroids. We evaluated the efficacy and safety of extracorporeal photopheresis (ECP) with a third-generation TC-V device in Japanese patients with cGVHD. Fifteen patients with steroid-resistant or -intolerant cGVHD after allogeneic hematopoietic stem cell transplantation participated in this multicenter open-label study. Extracorporeal photopheresis was conducted on days 1-3, week 1; days 1-2, weeks 2-12; and days 1-2, weeks 16, 20, and 24. The composite primary endpoint consisted of evaluation of response and changes in steroid dose 24 weeks after ECP initiation. Secondary endpoints included response over time, concomitant drug dose, quality of life, and safety. Twelve patients completed scheduled ECP therapy; eight (66.7%) showed a response at week 24. In all 15 patients, the mean (± standard deviation) steroid dose decreased 0.115 ± 0.230 mg/kg/day from screening to week 24. Five serious, potentially treatment-related adverse events (heart failure, thrombosis in the device, pneumonia, edema, and wheezing) occurred; none were fatal. This study confirmed that ECP using the TC-V device was effective, with an acceptable toxicity profile. Further studies in larger cohorts are clearly warranted to determine its optimal use in Japanese patients with cGVHD.

Combination of anti-CD4 antibody treatment and donor lymphocyte infusion ameliorates graft-versus-host disease while preserving graft-versus-tumor effects in murine allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is not only a well-established immunotherapy for hematologic malignancies, but is potentially useful for treating solid tumors refractory to available therapies. However, application of allo-HSCT to solid tumors is limited, despite the beneficial antitumor effects, by the risk of graft-versus-host disease (GVHD). CD4+ T cells have been implicated in several aspects of GVHD, and suppress antitumor CD8+ T-cell responses. In the present study, we investigated clinically applicable allo-HSCT protocols designed to maximize antitumor effects while reducing the risk of GVHD. We used a mouse model of allo-HSCT with s.c. tumors. We found that myeloablative conditioning was associated with better inhibition of tumor growth but with severe acute GVHD. Early treatment with anti-CD4 mAb substantially ameliorated GVHD while preserving antitumor effects, leading to improved survival in myeloablative allo-HSCT. Late treatment with anti-CD4 mAb also ameliorated GVHD to some extent. Donor lymphocyte infusion in GVHD mice treated with anti-CD4 mAb further suppressed tumor growth without exacerbating GVHD. Collectively, our results suggest that myeloablative allo-HSCT followed by anti-CD4 mAb treatment and donor lymphocyte infusion could be a potent and safe immunotherapy for patients with cancers refractory to available therapies.

Disseminated toxoplasmosis after hematopoietic stem cell transplantation showing unusual magnetic resonance images.

We herein report a patient who had disseminated toxoplasmosis after hematopoietic stem cell transplantation showing atypical clinical presentation and neuroimaging. Parkinsonism symptoms such as muscle rigidity, bradykinesia, tremor, and postural instability were initial manifestations. Magnetic resonance imaging showed diffuse symmetrical lesions of bilateral basal ganglia lacking ringed enhancement. Post-mortem analysis revealed multiple tachyzoites of Toxoplasma gondii in the basal ganglia, mid brain, cerebellum, and cardiac muscle.

Long-Lasting Graft-Derived Donor T Cells Contribute to the Pathogenesis of Chronic Graft-versus-Host Disease in Mice.

Chronic graft-versus-host disease (cGVHD) is a major complication in long-term survivors of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Graft-derived T cells (TG) have been implicated in the induction of cGVHD; however, the extent of their contribution to the pathogenesis of cGVHD remains unclear. Using a mouse model of cGVHD, we demonstrate that TG predominate over hematopoietic stem cell-derived T cells generated de novo (THSC) in cGVHD-affected organs such as the liver and lung even at day 63 after allo-HSCT. Persisting TG, in particular CD8+ TG, not only displayed an exhausted or senescent phenotype but also contained a substantial proportion of cells that had the potential to proliferate and produce inflammatory cytokines. Host antigens indirectly presented by donor HSC-derived hematopoietic cells were involved in the maintenance of TG in the reconstituted host. Selective depletion of TG in the chronic phase of disease resulted in the expansion of THSC and thus neither the survival nor histopathology of cGVHD was ameliorated. On the other hand, THSC depletion caused activation of TG and resulted in a lethal TG-mediated exacerbation of GVHD. The findings presented here clarify the pathological role of long-lasting TG in cGVHD.

Cytogenetically Unrelated Clones in Acute Myeloid Leukemia Showing Different Responses to Chemotherapy.

We report a case of acute myeloid leukemia (AML) with two cytogenetically unrelated clones. The patient was a 45-year-old male who was diagnosed with acute monoblastic leukemia (AMoL). Initial G-band analysis showed 51,XY,+6,+8,inv(9)(p12q13)c,+11,+13,+19[12]/52,idem,+Y[8], but G-band analysis after induction therapy showed 45,XY,-7,inv(9)(p12q13)c[19]/46,XY,inv(9)(p12q13)c[1]. Retrospective FISH analysis revealed a cryptic monosomy 7 clone in the initial AML sample. The clone with multiple trisomies was eliminated after induction therapy and never recurred, but a clone with monosomy 7 was still detected in myelodysplastic marrow with a normal blast percentage. Both clones were successfully eliminated after related peripheral blood stem cell transplantation, but the patient died of relapsed AML with monosomy 7. We concluded that one clone was de novo AMoL with chromosome 6, 8, 11, 13, and 19 trisomy and that the other was acute myeloid leukemia with myelodysplasia-related changes(AML-MRC) with chromosome 7 monosomy showing different responses to chemotherapy. Simultaneous onset of cytogenetically unrelated hematological malignancies that each have a different disease status is a rare phenomenon but is important to diagnose for a correct understanding of the disease status and for establishing an appropriate treatment strategy.

Allogeneic hematopoietic stem cell transplantation following reduced-intensity conditioning for mycosis fungoides and Sezary syndrome.

Advanced-stage mycosis fungoides and Sezary syndrome (MF/SS) have a poor prognosis. Allogeneic hematopoietic stem cell transplantation (HSCT), particularly using a reduced-intensity conditioning (RIC) regimen, is a promising treatment for advanced-stage MF/SS. We performed RIC-HSCT in nine patients with advanced MF/SS. With a median follow-up period of 954 days after HSCT, the estimated 3-year overall survival was 85.7% (95% confidence interval, 33.4-97.9%) with no non-relapse mortality. Five patients relapsed after RIC-HSCT; however, in four patients whose relapse was detected only from the skin, persistent complete response was achieved in one patient, and the disease was manageable in other three patients by the tapering of immunosuppressants and donor lymphocyte infusion, suggesting that graft-versus-lymphoma effect and 'down-staging' effect from advanced stage to early stage by HSCT improve the prognosis of advanced-stage MF/SS. These results suggest that RIC-HSCT is an effective treatment for advanced MF/SS.

Reduced supply of monocyte-derived macrophages leads to a transition from nodular to diffuse lesions and tissue cell activation in silica-induced pulmonary fibrosis in mice.

Pulmonary fibrosis (PF) is an intractable disorder with a poor prognosis. Lung macrophages have been reported to regulate both progression and remission of bleomycin-induced diffuse PF. However, it remains unclear how macrophages contribute to silica-induced progressive nodular PF and the associated tissue cell responses in vivo. We found that lack of monocyte-derived macrophages results in the formation of diffuse PF after silica instillation. We found that the proportion and the number of monocyte-derived macrophages were persistently higher in silica-induced progressive PF compared with bleomycin-induced PF. Surprisingly, in Ccr2(-/-) mice, in which monocyte-derived macrophage infiltration is impaired, silica administration induced diffuse PF with loose nodule formation and greater activation of tissue cells. In the diffuse lesions, the distribution of epithelial cells, distribution of myofibroblasts, and architecture of the basement membrane were disrupted. Consistent with the development of diffuse lesions, genes that were differentially expressed in CD45(-) tissue cells from the lung of wild-type and Ccr2(-/-) mice were highly enriched in human diffuse, progressive PF. In gene ontology network analyses, many of these genes were associated with tissue remodeling and included genes not previously associated with PF, such as Mmp14, Thbs2, and Fgfr4. Overall, these results indicate that monocyte-derived macrophages prevent transition from nodular to diffuse silica-induced PF, potentially by regulating tissue cell responses.

Ultra-high level of serum soluble interleukin-2 receptor at diagnosis predicts poor outcome for angioimmunoblastic T-cell lymphoma.

Angioimmunoblastic T-cell lymphoma (AITL) is a rare subtype of non-Hodgkin lymphoma and displays an aggressive clinical course with poor outcome. To identify prognostic factors for AITL, we retrospectively analyzed 36 patients with AITL. The median age was 74 years with 83% of the patients having advanced stage. Eighty-three percent received CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone)-like chemotherapies, resulting in an overall response rate of 63%. With a median follow-up of 9 years, the estimated overall survival at 5 years was 33.3%. Median serum level of soluble interleukin-2 receptor (sIL-2R) was 5615 U/mL at diagnosis, and over 10 000 U/mL of sIL-2R was identified as a significant poor prognostic factor, independent of the International Prognostic Index, Prognostic Index for peripheral T-cell lymphoma and Prognostic index for AITL (hazard ratio [HR], 4.42; 95% confidence interval [CI], 1.49-13.11; log-rank, p < 0.01). Our study shows that an ultra-high level of serum sIL-2R at diagnosis is a significant poor prognostic biomarker for AITL.

Loss of lymph node fibroblastic reticular cells and high endothelial cells is associated with humoral immunodeficiency in mouse graft-versus-host disease.

Graft-versus-host disease (GVHD) is a major risk factor for prolonged humoral immunodeficiency and vaccine unresponsiveness after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the underlying mechanisms for this immunodeficiency are poorly understood. In this article, we describe previously overlooked impacts of GVHD on lymph node (LN) stromal cells involved in humoral immune responses. In major- and minor-mismatched mouse allo-HSCT models, recipients with CD8(+) T cell-mediated GVHD suffered severe and irreversible damage to LN structure. These mice were susceptible to pathogenic infection and failed to mount humoral immune responses despite the presence of peripheral T and B cells. These humoral immune defects were associated with the early loss of fibroblastic reticular cells, most notably the CD157(+) cell subset, as well as structural defects in high endothelial venules. The disruption to these LN stromal cells was dependent on alloantigens expressed by nonhematopoietic cells. Blockade of the Fas-FasL pathway prevented damage to CD157(+) fibroblastic reticular cells and ameliorated LN GVHD. However, blockade of CD62L- or CCR7-dependent migration of CD8(+) T cells to the LN was insufficient to prevent stromal cell injury. Overall, our results highlight GVHD-associated loss of functional stromal cells and LN GVHD as a possible explanation for the prolonged susceptibility to infectious disease that is experienced by allo-HSCT patients.

Tracking of intertissue migration reveals the origins of tumor-infiltrating monocytes.

Myeloid cells such as monocytes and monocyte-derived macrophages promote tumor progression. Recent reports suggest that extramedullary hematopoiesis sustains a sizable reservoir of tumor-infiltrating monocytes in the spleen. However, the influence of the spleen on tumor development and the extent to which spleen monocytes populate the tumor relative to bone marrow (BM) monocytes remain controversial. Here, we used mice expressing the photoconvertible protein Kikume Green-Red to track the redistribution of monocytes from the BM and spleen, and mice expressing fluorescent ubiquitination-based cell-cycle indicator proteins to monitor active hematopoiesis in these tissues. In mice bearing late-stage tumors, the BM, besides being the major site of monocyte production, supplied the expansion of the spleen reservoir, replacing 9% of spleen monocytes every hour. Deployment of monocytes was equally rapid from the BM and the spleen. However, BM monocytes were younger than those in the spleen and were 2.7 times more likely to migrate into the tumor from the circulation. Partly as a result of this intrinsic difference in migration potential, spleen monocytes made only a minor contribution to the tumor-infiltrating monocyte population. At least 27% of tumor monocytes had traveled from the BM in the last 24 h, compared with only 2% from the spleen. These observations highlight the importance of the BM as the primary hematopoietic tissue and monocyte reservoir in tumor-bearing mice, despite the changes that occur in the spleen monocyte reservoir during tumor development.

Bone marrow graft-versus-host disease: evaluation of its clinical impact on disrupted hematopoiesis after allogeneic hematopoietic stem cell transplantation.

Idiopathic cytopenias are frequently observed in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We have previously reported the effect of graft-versus-host disease (GVHD) on bone marrow (BM) in murine models, indicating that the osteoblast injury mediated by donor T cells was associated with bone marrow suppression and delayed immune reconstitution. In this study, we prospectively evaluated the relevance of these findings in 51 patients. Patients with chronic GVHD manifested the loss of osteoblasts, contributing to cytopenic symptoms (P = .0427 compared with patients without cytopenic symptoms). The loss of osteoblasts was significantly associated with the extensive type of chronic GVHD (P = .012), and flow cytometric analyses revealed lower numbers of CD19(+) B cells and a significantly increased CD4 to CD8 ratio (P = .0002) in these patients. Our data, for the first time to our knowledge, summarize the detailed analyses of the effect of GVHD on BM in the clinical allo-HSCT patients.