Impact of Intestinal Microbiota on Reconstitution of Circulating Monocyte, Dendritic Cell, and Natural Killer Cell Subsets in Adults Undergoing Single-Unit Cord Blood Transplantation.

The intestinal microbiota plays a fundamental role in the development of host innate immune cells, such as monocytes, dendritic cells (DCs), and natural killer (NK) cells. We examined the association between intestinal microbiota and subsequent immune reconstitution of circulating monocyte, DC, and NK cell subsets in 38 adult patients undergoing single-unit cord blood transplantation (CBT). A higher diversity of intestinal microbiota at 1 month was significantly associated with higher counts of plasmacytoid DCs at 7 months after CBT, as measured by the Chao1 index. Principal coordinate analysis of unweighted UniFrac distances showed significant differences between higher and lower classical monocyte reconstitution at 7 months post-CBT. The families Neisseriaceae, Burkholderiaceae, Propionibacteriaceae, and Coriobacteriaceae were increased in higher classical monocyte reconstitution at 7 months post-CBT, whereas the family Bacteroidaceae was increased in lower classical monocyte reconstitution at 7 months post-CBT. These data show that intestinal microbiota composition affects immune reconstitution of classical monocyte and plasmacytoid DCs following single-unit CBT.

Reconstitution of Circulating Mucosal-Associated Invariant T Cells after Allogeneic Hematopoietic Cell Transplantation: Its Association with the Riboflavin Synthetic Pathway of Gut Microbiota in Cord Blood Transplant Recipients.

Mucosal-associated invariant T (MAIT) cells are a type of innate lymphocyte and recognize riboflavin (vitamin B2) synthesis products presented by MHC-related protein 1. We investigated long-term reconstitution of MAIT cells and its association with chronic graft-versus-host disease (cGVHD) in a cross-sectional cohort of 173 adult patients after allogeneic hematopoietic cell transplantation. According to donor source, the number of MAIT cells significantly correlated with time after cord blood transplantation (CBT) but not with time after bone marrow transplantation or peripheral blood stem cell transplantation. The number of MAIT cells was significantly lower in patients with cGVHD compared with patients without cGVHD. We also examined the association between MAIT cell reconstitution and gut microbiota as evaluated by 16S ribosomal sequencing of stool samples 1 mo post-CBT in 27 adult patients undergoing CBT. The diversity of gut microbiota was positively correlated with better MAIT cell reconstitution after CBT. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis indicated that amounts of ribB and ribA genes were significantly higher in the microbiomes of patients with subsequent MAIT cell reconstitution after CBT. In conclusion, long-term MAIT cell reconstitution is dependent on the type of donor source. Our data also unveiled an important role for the interaction of circulating MAIT cells with gut microbiota in humans.

T memory stem cells after allogeneic haematopoietic cell transplantation: unique long-term kinetics and influence of chronic graft-versus-host disease.

T memory stem cells (TSCMs) are a subset of primitive T cells capable of both self-renewal and differentiation into all subsets of memory and effector T cells. Therefore, TSCMs may play a role in immune reconstitution and graft-versus-host disease (GVHD) in patients receiving allogeneic haematopoietic cell transplantation (HCT). We conducted a cross-sectional study to evaluate the proportions, absolute counts, phenotypes and functions of TSCMs in 152 adult patients without disease recurrence at least 12 months after undergoing HCT. CD4+ TSCMs were negatively correlated with number of months after transplantation in HCT patients that received cord blood transplantation, but not in patients that received bone marrow transplantation or peripheral blood stem cell transplantation. The proportions and absolute counts of CD4+ TSCMs and expression levels of inducible co-stimulator (ICOS) in CD8+ TSCMs were significantly higher in patients with mild and moderate/severe cGVHD compared to patients without cGVHD. These data suggested that, more than 12 months after allogeneic HCT, the kinetics of CD4+ TSCMs were dependent on the type of donor source, and further that CD4+ TSCMs and ICOS levels in CD8+ TSCMs were associated with cGVHD.

Circulating monocyte subsets in human chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a major cause of late morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT). Monocytes/macrophages play a central role in inflammation, tissue repair, and fibrosis, which are the main clinical features of cGVHD. Here, we examined the expression levels of activation markers, chemokine receptors, and scavenger receptors for each circulating monocyte subset in 145 patients without disease recurrence at least 12 months after undergoing allogeneic HCT. There were no significant differences in the numbers and the proportions of each monocyte subset between patients without cGVHD and those with mild or moderate/severe cGVHD. Lower expression of CCR5 on classical monocytes, and higher expression of CD204 and lower expression of CX3CR1 on non-classical monocytes were associated with joint, and lung cGVHD, respectively. These data showed that alterations of activation markers and chemokine and scavenger receptors in each circulating monocyte subset were associated with the development of organ-specific cGVHD. Alterations of surface markers in each circulating monocyte subset may be candidate biomarkers for cGVHD.

Monocyte subsets and their phenotypes during treatment with BCR-ABL1 tyrosine kinase inhibitors for Philadelphia chromosome-positive leukemia.

BCR-ABL1 tyrosine kinase inhibitors (TKIs) are effective agents in the treatment of Philadelphia chromosome-positive leukemia. However, vascular events have developed in some patients receiving each TKI. The perturbation of circulating monocyte subsets and their expressions of chemokine and scavenger receptors are associated with the development of cardiovascular events. Here, we examined the subsets of circulating monocytes and their phenotypes in 51 patients treated with imatinib, nilotinib, and dasatinib, and 11 healthy subjects in our institute. Except for a negative association between the number of classical monocytes and imatinib treatment, the proportions and numbers of monocyte subsets were not significantly associated with TKI treatment. However, chemokine receptors, CCR2, CX3CR1 on classical monocytes, and scavenger receptor, CD204, on intermediate and non-classical monocytes were significantly associated with TKIs. These data demonstrated the relationships between alterations of chemokine and scavenger receptors on different monocyte subsets and the TKI treatments.

Cytokine Profiles of Pre-Engraftment Syndrome after Single-Unit Cord Blood Transplantation for Adult Patients.

Clinical manifestation of high-grade fever and skin rash before neutrophil engraftment, termed pre-engraftment syndrome (PES) or pre-engraftment immune reaction, has been frequently observed after cord blood transplantation (CBT). The pathophysiology of PES is poorly understood, but cytokine storm during the early phase of CBT is thought to be 1 of the main cause of PES. However, the cytokine profiles of PES after CBT are unclear. Therefore, we examined the relationship between serum cytokine profiles and PES in 44 adult patients who received CBT in our institution between February 2013 and June 2016. Serum levels of 21 cytokines, IL-1ß, IL-2, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-12p70, IL-13, IL-17A, IL-17F, IL-18, IL-21, IL-22, IL-23, IL-33, monocyte chemoattractant protein-1, IFN-α, IFN-γ, and TNF-α, were measured by multiplex bead assays using a flow cytometer. The median time until the absolute neutrophil count was >.5 × 109/L was 21 days (range, 15 to 41 days). The cumulative incidence of PES was 79.6% (95% confidence interval, 63.3% to 88.5%) at 60 days after CBT. Serum levels of IL-5 (P = .009) and IL-6 (P = .01) at 2 weeks were significantly higher in patients who developed PES compared with those who did not develop PES. The conversion from naïve to effector or central memory phenotype of T cells was observed in PES. These data indicate that elevations of IL-5 and IL-6 around the time of clinical manifestation may be possible biomarkers for PES after CBT.