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SummaryThe stem cell theory that all blood cells are derived from hematopoietic stem cell (HSC) is a central dogma in hematology. However, various types of blood cells are already produced from hemogenic endothelial cells (HECs) before the first HSCs appear at embryonic day (E)11 in the mouse embryo. This early blood cell production from HECs, called HSC-independent hematopoiesis, includes primitive and definitive erythromyeloid progenitors that transiently support fetal blood homeostasis until HSC-derived hematopoiesis is established. Lymphoid potential has traditionally been detected in the extra-embryonic yolk sac (YS) and/or embryos before HSC emergence, but the actual presence of lymphoid progenitors at this stage remains unknown. In addition, whether HSCs in the fetal liver are the main source of innate-like B-1a cells has been controversial. Here, using complementary lineage tracing mouse models, we show that HSC-independent multipotent progenitors (MPPs) and HSC-independent adoptive B-lymphoid progenitors persist into adult life. Furthermore, HSCs minimally contribute to the peritoneal B-1a cell pool; most B-1a cells are originated directly from ECs in the YS and embryo and HSC-independent for life. Our discovery of extensive HSC-independent MPP and B-lymphoid progenitors in adults attests to the complex blood developmental dynamics through embryo to adult that underpin the immune system and challenges the paradigm of HSC theory in hematology.

The stem cell theory that all blood cells are derived from hematopoietic stem cell (HSC) is a central dogma in hematology. However, exceptions are the fetal hematopoiesis in which primitive and definitive type of erythromyeloid cells are already produced from hemogenic endothelial cells (HECs) before the first HSC emergence in the mouse embryo. This early blood cell production prior to HSC emergence is called HSC-independent hematopoiesis and considered to be transient during fetus. Recent lineage-tracing studies revealed that some tissue-resident innate immune cells (e.g. brain microglia, mast cells, and certain types of γδT cells) are also produced independently of HSCs from early extra-embryonic yolk-sac (YS). Definitive T&B-lymphoid potential and multi-potent progenitor (MPP) potential have been detected in the YS and/or embryos in in vitro studies, however, the physiological presence of these cells in the embryo at pre-HSC stage remains unknown. In addition, whether HSCs in the fetal liver are the main source of innate-like B-1a cells has been controversial. Here, using complementary lineage tracing mouse models, we show that HSC-independent MPPs and HSC-independent adoptive T & B-lymphocytes persist into adult life and are gradually replaced by HSC-derived cells. Furthermore, we found that HSCs minimally contribute to the peritoneal B-1a cells, and most B-1a cells are originated directly from ECs in the YS and embryo and HSC-independent for life. Our discovery of extensive HSC-independent MPP and adoptive lymphocytes in adults attests to the complex blood developmental dynamics through embryo to adult that underpin the immune system and challenges the paradigm of HSC theory in hematology. Supported by grant from NIH R01AI121197.

Innate-immune like B-1a cells are unique in its functions and developmental origin compared to conventional adaptive immune B-cells (B-2 cells). Especially, their origin and developmental pathway have been argued over four decades between two proposed models: the lineage model and the selection model. Although many transplantation studies support the lineage model in which B-1a cells are derived from fetal progenitors, contradictory results of fetal liver transplantation studies raise a question as to whether fetal liver hematopoietic stem cells (HSCs) are the primary source of the peritoneal B-1a cells. In order to address this question, we took two approaches using transplantation assays and lineage tracing mouse models that enable us to trace Tomato+ progeny of endothelial cells (ECs, Cdh5CreERT mice) and HSCs (Fgd5CreERT2 mice) at a time of Tamoxifen (Tam) injection, respectively. Results: First, we transplanted HSC-precursors (pre-HSCs) from the aorta-gonad-mesonephros (AGM) region of the mouse embryo at embryonic (E) 11.5 into irradiated NSG neonates. Interestingly, we found more B-1a repopulating capacity than multi-lineage in the pre-HSC population. The lineage tracing of hemogenic ECs revealed that B-1a progenitors and HSCs were simultaneously produced from ECs during E9.5 to 10.5, but B-1a production is diminished after E11.5 while HSC were still labeled at E11.5. The HSC-tracing model demonstrated the minimal contribution of FL HSCs to the postnatal B-1a cell pool. Conclusion: Our data addressed the long-lasting controversy and showed HSC-independent B-1a cell development in the mouse embryo.

The aim of the present study was to explore serum biomarkers for the pathology of IgA nephropathy using serum proteomics. The subjects were 57 patients with IgA nephropathy who were divided into two groups (group 1, n=25; group 2, n=32) and 14 healthy controls. Serum protein profiles were analyzed using the ProteinChip surface-enhanced laser desorption ionization (SELDI) system. Associations between signal intensities of proteins and histological findings in patients with IgA nephropathy were studied in group 1. Serum levels of a candidate biomarker protein (complement component C4a desArg) for IgA nephropathy were determined by enzyme linked-immunosorbent assay (ELISA) in group 2 and the relationships of these levels with histological findings were evaluated. There were significant differences in 93 protein signals between patients in group 1 and controls. Among these signals, 3 proteins at 8592, 8757 and 8806 m/z were significantly correlated with the severity of glomerular lesions. The protein at 8592 m/z was identified as C4a desArg and the signal intensity of 8592 m/z was strongly correlated with serum C4a levels, including C4a desArg, determined by ELISA. In addition, the serum levels of C4a (mainly C4a desArg) were significantly higher in patients in group 2 compared to controls and were correlated with the severity of glomerular lesions and with mesangial hypercellularity scores. In conclusion, the serum levels of complement C4a desArg are significantly higher in patients with IgA nephropathy compared to healthy controls and are significantly correlated with the severity of glomerular lesions and mesangial hypercellularity scores. Thus, serum C4a desArg is a potential biomarker for the severity of histological findings in patients with IgA nephropathy.

The mechanisms underlying the pathogenesis of immunoglobulin A (IgA) nephropathy (IgAN) are not well understood. In this study, we examined gene expression profiles in kidneys obtained from mice with high serum IgA levels (HIGA mice), which exhibit features of human IgAN. Female inbred HIGA, established from the ddY line, were used in these experiments. Serum IgA levels, renal IgA deposition, mesangial proliferation, and glomerulosclerosis were increased in 32-week-old HIGA mice in comparison to ddY animals. By microarray analysis, five genes were observed to be increased by more than 2.5-fold in 32-week-old HIGA in comparison to 16-week-old HIGA; these same five genes were decreased more than 2.5-fold in 32-week-old ddY in comparison to 16-week-old ddY mice. Of these five genes, insulin-like growth factor (IGF) binding protein (IGFBP)-1 exhibited differential expression between these mouse lines, as confirmed by quantitative RT-PCR. In addition, serum IGFBP-1 levels were significantly higher in patients with IgAN than in healthy controls. In patients with IgAN, these levels correlated with measures of renal function, such as estimated glomerular filtration rate (eGFR), but not with sex, age, serum IgA, C3 levels, or IGF-1 levels. Pathologically, serum IGFBP-1 levels were significantly associated with the severity of renal injury, as assessed by mesangial cell proliferation and interstitial fibrosis. These results suggest that increased IGFBP-1 levels are associated with the severity of renal pathology in patients with IgAN.

The natural history of hepatitis C virus (HCV) carriers and the effect of ursodeoxycholic acid (UDCA) have not been fully elucidated among hemodialysis (HD) patients.Eighty-four anti-HCV antibody- and HCV RNA-positive and 154 anti-HCV antibody-negative HD patients who were retrospectively observed for at least 3 years were analyzed. We investigated the factors associated with thrombocytopenia (1.3 x 10(5)/microL) and decreased platelet count (PLT) (more than 20% decrease during the follow-up period), which were considered to be indicators of hepatic fibrosis. In addition, another 16 HD patients with HCV who received 300 mg/day UDCA orally for at least 6 months were investigated. Changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT) and PLT were assessed.After the 60.3-months mean follow-up period, HCV infection was independently associated with both thrombocytopenia [odds ratio (OR) 2.589] and decreased PLT (OR 2.339) in 238 HD patients. In 84 HD patients with HCV, the average ALT levels (or = 15 IU/L) during the follow-up period was associated with thrombocytopenia (OR 3.882) and decreased PLT (OR 4.470). In addition, ALT, AST and GGT significantly decreased at 6 months after starting UDCA, but PLT did not change in 16 HD patients with HCV.These results indicate that HCV infection is a risk for thrombocytopenia which should be associated with hepatic fibrosis in HD patients. In addition, the clinical course of ALT levels predicts the progression of thrombocytopenia, and UDCA may effectively lower ALT levels in HD patients with HCV.

59歳, 女性. 2005年6月皮疹が出現し, 皮膚生検にて成人T細胞性白血病 (ATL) と診断され, 内服治療を開始した. 2006年4月まで経過は良好であったが, 5月より表在リンパ節腫脹, 7月には腎機能障害, 高カルシウム血症が出現し, 8月11日当科に入院した. 入院時尿素窒素80.9mg/dL, 血清クレアチニン5.1mg/dLと著明な上昇を認めた. さらに全身浮腫と胸腹水の貯留を認めたために急性腎不全と診断し, 血液透析を併用しながら多剤併用化学療法を行った. 化学療法前の腹部エコー検査では両側腎ともびまん性に腫大し, 皮質の輝度上昇と錐体のエコーレベルの低下も認められたが, 腎盂, 腎杯の拡張は認められなかった. 腹部単純CT検査でも腎臓は両側ともびまん性に腫大し, 内部に不整な高吸収域が散在していた. 化学療法後には両腎腫大は改善し, 腎機能も改善したために血液透析から離脱可能となったが, ATL増悪のために死亡した. 病理解剖所見では, ATL細胞浸潤が糸球体や尿細管への浸潤は認めず, 間質へのびまん性浸潤とそれによる尿細管の圧迫所見を認めた. ATLで腎腫大のみられる場合には, ATL細胞の浸潤が急性腎不全の原因となることがあり, 透析療法の併用を考慮した化学療法が必要となる場合がある.

Objective The role of oxidative stress in IgA nephropathy (IgAN), the most common type of primary glomerulonephritis, is unknown. We evaluated the clinical significance of serum levels of oxidative stress markers, thioredoxin (TRX) and manganese superoxide dismutase (MnSOD), in patients with IgAN. Methods Forty-eight patients with histologically confirmed IgAN and 14 healthy subjects were enrolled in this study. Serum samples from 14 IgAN patients were obtained after tonsillectomy, a procedure hypothesized to be an effective treatment for IgAN. Results Serum TRX levels were significantly higher in patients with IgAN than in healthy subjects (mean [ng/mL]; 49.5 vs.14.4, p

A 59-year-old woman was admitted to our hospital because of a pancreatic mass lesion. Serum gamma-globulin and IgG4 levels were elevated to 2.2 g/dL and 1,310 mg/dL, respectively. Computed tomography examination revealed multiple low-density areas without enhancement by contrast in the pancreatic body and bilateral kidneys. Endoscopic retrograde cholangiopancreatography images demonstrated diffuse narrowing of the main pancreatic duct with an irregular wall from the body to the tail of the pancreas. Positron emission tomography examination revealed intense 18F-fluorodeoxyglucose uptake by the pancreas and kidneys. Accordingly, the patient was diagnosed as having IgG4-related autoimmune pancreatitis. In addition, the findings of a renal tissue specimen obtained by biopsy demonstrated IgG4-positive plasma cell infiltration in both abnormal mass lesions and normal regions by imaging, leading to the final diagnosis of IgG4-related sclerotic disease. The patient was treated with prednisolone (30 mg/day), and the size of the pancreatic and renal lesions markedly decreased four weeks later. We report here a rare case of IgG4-related autoimmune pancreatitis with multiple renal lesions, which were confirmed by renal biopsy.