Yusuke Meguri

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.

Graft-versus-leukemia effect with a WT1-specific T-cell response induced by azacitidine and donor lymphocyte infusions after allogeneic hematopoietic stem cell transplantation

BACKGROUND Azacitidine (Aza) and donor lymphocyte infusion (DLI) therapy has recently been reported as an effective salvage therapy for relapsed acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Despite the high response rate and relatively long period of remission, most patients relapse again. The immunologic mechanism of the response and limited efficacy remain unknown. CASE REPORT Aza + DLI therapy was performed for a patient with therapy-related MDS (t-MDS), who had relapsed after allogeneic peripheral blood stem cell transplantation. We observed a powerful graft-versus-leukemia (GVL) effect accompanied by an evident Wilms tumor antigen 1 (WT1)-specific CD8 T-cell response. Remission continued for 15 months, but finally the patient relapsed. The kinetics of the WT1-specific CD8 T cells were inversely associated with WT1 messenger RNA (mRNA), suggesting a WT1-driven GVL effect. DISCUSSION A difference of T-cell phenotype between the whole T cells and the WT1-specific CD8 T cells was observed. It is of note that the memory phenotype of the WT1-specific T cell was limited and decreased early. The immunoescape mechanism was partly supported by loss of the memory phenotype due to failure of expansion and differentiation. CONCLUSION Our data suggested that a WT1-specific T-cell response at least partly contributes to the GVL effect induced by Aza + DLI. A strategy for maximizing and maintaining the memory phenotype of the CTL may be required for durable remission.

Intraocular Relapse with Hypopyon and Retinal Infiltrates after Chemotherapy and Peripheral Blood Stem Cell Transplantation for Extranodal NK/T-Cell Lymphoma

We report a case of intraocular relapse of extranodal NK/T-cell lymphoma with anterior chamber hypopyon and retinal infiltrates. A 55-year-old man developed fever, malaise, anorexia, and hepatosplenomegaly, and was diagnosed with NK/T-cell lymphoma by liver biopsy. He underwent 2 courses of SMILE (dexamethasone, methotrexate, ifosfamide, L-asparaginase, and etoposide) chemotherapy, followed by myeloablative peripheral blood stem cell transplantation, donated by his brother. Two months later, he developed high-grade fever, hepatosplenomegaly, and peritoneal lymphadenopathy, and the relapse with hemophagocytic syndrome was diagnosed by bone marrow biopsy. He underwent 2 courses of SMILE salvage chemotherapy, followed by non-myeloablative peripheral blood stem cell transplantation, donated by his son. Two months later, he noticed blurred vision in both eyes. The right eye had aqueous cells and keratic precipitates, but no retinal lesions. The left eye had hypopyon in the anterior chamber with numerous aqueous cells, and retinal white infiltrates with retinal hemorrhages. The aqueous cells, obtained by anterior chamber paracentesis, were positive for CD3, CD56, and Epstein-Barr virus-encoded RNA, but negative for CD20 by immunocytochemical staining. Head magnetic resonance imaging demonstrated white matter lesions in the anterior to parietal lobes on the right side. The patient underwent intrathecal methotrexate injection and external beam radiation at 40 Gy, covering the entire brain and both eyes. The retinal lesions and hypopyon disappeared. Two months later, the patient died of renal failure, and autopsy demonstrated multi-organ involvement of lymphoma cells. In conclusion, we report a case of NK/T-cell lymphoma relapse with intraocular lesions, after combined chemotherapy and hematopoietic stem cell transplantation.

A case report of TAFRO syndrome successfully treated by immunosuppressive therapies with plasma exchange

Dear Editor, TAFRO syndrome is an emerging clinical entity, presenting as systemic inflammatory disorder characterized by thrombocytopenia (T), anasarca (A), fever (F), reticulin fibrosis, renal failure (R), and organomegaly (O). Together, these clinical features have been described as TAFRO syndrome, which is considered to be the aggressive variant of multicentric Castleman’s disease (MCD) [1]. We report the first case for which plasma exchange (PE) was effective in treating severe clinical symptoms presenting as multi-organ failure (MOF). A 52-year-old woman presented with fever and systemic edema. The blood examination showed thrombocytopenia, anemia, renal failure, and elevated inflammation markers (CRP, 25.3 mg/dl; interleukin [IL]-6, 250 pg/ml). Computed tomography revealed multiple lymphadenopathies. The histopathological findings of the mediastinal mass and the bone marrow biopsy showing reticulin fibrosis were compatible with TAFRO syndrome. Steroid pulse, cyclophosphamide, tocilizumab, and rituximab were given under mechanical vent i l a t ion for resp i ra tory fa i lu re , and cont inuous hemodiafiltration (CHDF) was given for renal failure. However, clinical features, including hyper-bilirubinemia (T.Bil, 17 mg/dl), rapidly worsened. We started PE for MOF with liver dysfunction. After the initiation of PE, the jaundice quickly declined, renal function began to improve, and systemic edema lessened. Eventually, CHDF was discontinued. While the patient’s prognosis was complicated by the development of severe Stenotorophomonous maltophilia (S. maltophilia) pneumonia and bacterial sepsis, the features of TAFRO, including renal dysfunction and jaundice, began to improve. Consequently, she recovered from MOF and the severe infections, and was eventually discharged with complete recovery. The primary purpose of treatment of TAFRO is to control systemic inflammation, as the aberrant increase of inflammatory cytokines, including IL-6 and vascular endothelial growth factor, have been suggested as the pathogenesis of TAFRO syndrome. In some case series of TAFRO syndrome [2], the majority of patients were treated with corticosteroids, and cyclosporine or tocilizumabwere also reported to be effective [3]. Chemotherapies such as CHOP, rituximab, bortezomib, and thalidomide have also been used [4]. Intriguingly, one case achieved a remission of clinical symptoms for 6 months through only a debulking surgery of a large mediastinal mass [5]. Thus, both reduction and suppression of cytokineproducing cells seem to be important for treating TAFRO syndrome. In the current case, severe symptoms and bilirubinemia persisted after intensive treatment with immunosuppressive therapies. However, immediately after initiation of PE, severe clinical features were improved, suggesting that PE might be a useful therapeutic option in patients with TAFRO syndrome refractory to intensive immunosuppressive therapies. PE has been widely used to remove pathogenic substances, such as cytokines, antibodies, antigen-complexes, and bilirubin, from patients’ plasma. Although IL-6 is generally thought to have a strong correlation with the pathogenesis of MCD * Toru Kiguchi kiguchi-t@umin.ac.jp

A case of reversible cerebral vasoconstriction syndrome developing during treatment of adult aplastic anemia

Dear Editor, Reversible cerebral vasoconstriction syndrome (RCVS) refers to a group of disorders character ized by Bthunderclap headaches^ and diffuse narrowing of the cerebral arteries [1]. RCVS sometimes develops after the use of immunosuppressants that are frequently used to treat hematological diseases. However, only two pediatric cases of RCVS in patients with a hematological disease have been reported [2, 3]. Herein, we report the first adult case of RCVS in a patient with aplastic anemia (AA). A 58-year-old female presented with a severe headache and hypertension on day 5 after commencement of oral cyclosporine A (CsA) and rabbit anti-thymocyte globulin (ATG) to treat severe AA. Initially, she was given analgesics for the headache and CsA because head CT scans showed no evidence of bleeding of the brain. However, her headache persisted, and we stopped CsA on day 11. Thereafter, her headache ceased, but on day 13, she complained of a bilateral visual field defect. Magnetic resonance imaging revealed multiple small cerebral infarctions, and magnetic resonance angiography (MRA) revealed diffuse vasoconstrictions of the cerebral arteries (Fig. 1). Her neurological findings and cerebral images gradually improved. On day 217, she was retreated with low-dose CsA and exhibited no neural sequelae. The blood cell numbers increased, but she remained transfusion-dependent (except for platelets); we scheduled monthly erythrocyte transfusions. It is important to reduce or stop a drug that is causing RCVS, such as CsA and rabbit-ATG [2, 3]. The hypertension and thunderclap headaches ceased immediately after CsA was stopped, but the possibility that rabbit-ATG induced RCVS cannot be discounted. Magnesium sulfate [4] and calcium antagonists [3, 5] are useful RCVS therapies, reducing blood pressure and dilating the cerebral vessels. Retreatment of AA with CsA is sometimes inevitable; Ueki et al. retreated AA by CsA with lomerizine without relapsing RCVS [3]. As the hypertension improved after CsA was stopped, we did not use calcium antagonists. We commenced CsA at a low dose and controlled the blood level because side-effect development depends on the CsA blood concentration [6]. A switch to tacrolimus is one possible strategy when posterior reversible encephalopathy syndrome (PRES) develops [7]. Tacrolimus also causes RCVS [8], but is effective against AA [9]. The class effect of the various calcineurin inhibitors on RCVS remains poorly known; these materials may be useful treatment options. A diagnosis of RCVS requires MRA, but MRA findings are sometimes not initially apparent; repeat MRA is recommended ≥ 1 week after onset [10]. Only two cases of RCVS in patients with hematological diseases have been reported despite many such patients taking drugs * Toru Kiguchi kiguchi-t@umin.ac.jp