Takeru Asano

PD-1 modulates regulatory T-cell homeostasis during low-dose interleukin-2 therapy

CD4+Foxp3+ regulatory T cells (Tregs) play a central role in the maintenance of immune tolerance after hematopoietic stem cell transplantation. We previously reported that low-dose interleukin-2 (IL-2) therapy increased circulating Tregs and improved clinical symptoms of chronic graft-versus-host-disease (cGVHD); however, the mechanisms that regulate Treg homeostasis during IL-2 therapy have not been well studied. To elucidate these regulatory mechanisms, we examined the role of inhibitory coreceptors on Tregs during IL-2 therapy in a murine model and in patients with cGVHD. Murine studies demonstrated that low-dose IL-2 selectively increased Tregs and simultaneously enhanced the expression of programmed cell death 1 (PD-1), especially on CD44+CD62L+ central-memory Tregs, whereas expression of other inhibitory molecules, including CTLA-4, LAG-3, and TIM-3 remained stable. PD-1-deficient Tregs showed rapid Stat5 phosphorylation and proliferation soon after IL-2 initiation, but thereafter Tregs became proapoptotic with higher Fas and lower Bcl-2 expression. As a result, the positive impact of IL-2 on Tregs was completely abolished, and Treg levels returned to baseline despite continued IL-2 administration. We also examined circulating Tregs from patients with cGVHD who were receiving low-dose IL-2 and found that IL-2-induced Treg proliferation was promptly followed by increased PD-1 expression on central-memory Tregs. Notably, clinical improvement of GVHD was associated with increased levels of PD-1 on Tregs, suggesting that the PD-1 pathway supports Treg-mediated tolerance. These studies indicate that PD-1 is a critical homeostatic regulator for Tregs by modulating proliferation and apoptosis during IL-2 therapy. Our findings will facilitate the development of therapeutic strategies that modulate Treg homeostasis to promote immune tolerance.

Vigorous inflammatory responses in noninfectious pulmonary complication induced by donor lymphocyte infusion

Donor lymphocyte infusion (DLI) is used for treatment of hematologic malignancy relapse or mixed chimerism after allogeneic hematopoietic stem cell transplantation. Although graft‐versus‐host disease is well recognized as one of the adverse effects of DLI, there are limited reports on noninfectious pulmonary complications (NIPCs) after DLI.

Complete resolution of steroid-resistant organizing pneumonia associated with myelodysplastic syndrome following allogeneic hematopoietic cell transplantation

Pulmonary complications in patients with hematological malignancies are often caused by infection but are sometimes associated with an underlying disease such as organizing pneumonia (OP). Here, we report a case of life-threatening steroid-resistant OP associated with myelodysplastic syndrome (MDS) and successfully performed allogeneic hematopoietic cell transplantation (HSCT). A 33-year-old female with refractory anemia with excess blasts-1 that had progressed from refractory anemia with ringed sideroblasts and concomitant Sweet’s syndrome was admitted. Multiple pulmonary infiltrates were revealed on a chest computed tomography scan, which progressively worsened even after chemotherapy and corticosteroid therapy. No evidence of infection was observed in bronchoalveolar lavage fluid. A histological examination of a transbronchial lung biopsy specimen showed lymphocyte invasion with fibrosis, indicating that the pulmonary infiltrates were OP associated with MDS. Before transplantation, she suffered from respiratory failure and required oxygen supplementation. She developed idiopathic pneumonitis syndrome on day 61 that responded well to corticosteroid therapy, and the OP pulmonary infiltrates improved gradually after HSCT, She was discharged on day 104 and is well without recurrence of OP or MDS 2 years after HSCT.

Asymmetrical and Isolated Hypoglossal Nerve Palsy Accompanied by a New Subset of Anti-ganglioside Antibodies in a Patient with Diffuse Large B Cell Lymphoma

Malignant lymphoma sometimes involves peripheral nerves due to paraneoplastic syndrome associated with anti-ganglioside antibodies. We report a very rare case of malignant lymphoma accompanied by an asymmetrical and isolated hypoglossal nerve palsy associated with a new subset of anti-ganglioside antibodies. Magnetic resonance imaging and 18F-2-deoxy-2-fluoro-D-glucose position emission tomography showed no abnormalities of the hypoglossal nerve nucleus; however, the patient’s serum was positive for anti-sulfated glucuronyl paragloboside IgM antibodies as well as anti-GM1 IgM and anti-GQ1b IgM antibodies. The present case might suggest a paraneoplastic asymmetrical and isolated hypoglossal nerve palsy associated with a new subset of anti-ganglioside antibodies.

Progressive multifocal leukoencephalopathy after T‐cell replete HLA‐haploidentical transplantation with post‐transplantation cyclophosphamide graft‐versus‐host disease prophylaxis

A 52‐year‐old man suffered from progressive multifocal leukoencephalopathy (PML) after human leukocyte antigen (HLA)‐haploidentical transplantation with post‐transplantation cyclophosphamide (PTCY). Mirtazapine, mefloquine, and cytarabine failed to improve his symptoms, and he finally died 4.5 months after PML onset. This is the first case report of a patient with PML after HLA‐haploidentical transplantation with PTCY. Although T‐cell replete HLA‐haploidentical transplantation with PTCY has enabled early immune reconstitution, PML should be considered if a patients mental condition deteriorates.