Tfl deletion induces extraordinary Cxcl13 secretion and cachexia in VavP-Bcl2 transgenic mice

STATEMENT OF SIGNIFICANCE

Loss of TFL, found in several types of lymphoma, induces excessive CXCL13 secretion through RNA dysregulation contributing to body weight loss and early death in lymphoma model mice. Follicular lymphoma (FL) is associated with overexpressed BCL-2 and other genetic aberrations, including 6q-. We identified a novel gene on 6q25, "Transformed follicular lymphoma (TFL)," from a transformed FL. TFL regulates several cytokines via mRNA degradation, which has been suggested to underlie resolving inflammation. Fluorescence in situ hybridization revealed a deletion of TFL occurred in 13.6% of various B-cell lymphoma samples. We developed VavP-bcl2 transgenic, TFL deficit mice (Bcl2-Tg/Tfl -/-) to seek how TFL affects disease progression in this lymphoma model. While Bcl2-Tg mice developed lymphadenopathy and died around 50 weeks, Bcl2-Tg/Tfl -/- mice lost body weight around 30 weeks and died about 20 weeks earlier than Bcl2-Tg mice. Furthermore, we found a unique B220-IgM+ cell population in the bone marrow of Bcl2-Tg mice. cDNA array in this population revealed that Cxcl13 mRNA in Bcl2-Tg/Tfl -/- mice expressed significantly higher than Bcl2-Tg mice. In addition, bone marrow extracellular fluid and serum showed an extremely high Cxcl13 concentration in Bcl2-Tg/Tfl -/- mice. Among bone marrow cells, the B220-IgM+ fraction was the main producer of Cxcl13 in culture. A reporter assay demonstrated TFL regulates CXCL-13 via induction of 3'UTR mRNA degradation in B lineage cells. These data suggest Tfl regulates Cxcl13 in B220-IgM+ cells in the bone marrow, and a very high concentration of serum Cxcl13 arising from these cells may contribute to early death in lymphoma-bearing mice. Since several reports have suggested the association of CXCL13 expression with lymphoma, these findings provide new insights into cytokine regulation via TFL in lymphoma.

Mobilization efficiency is critically regulated by fat via marrow PPARδ

The mobilization efficiency of hematopoietic stem/progenitor cells from bone marrow (BM) to circulation by granulocyte colony-stimulating factor (G-CSF) is dramatically dispersed in humans and mice with no mechanistic lead for poor mobilizers. The regulatory mechanism for mobilization efficiency by dietary fat was assessed in mice. Fat-free diet (FFD) for 2 weeks greatly increased mobilization compared to normal diet (ND). The BM mRNA level of peroxisome proliferator-activated receptor δ (PPARδ), a receptor for lipid mediators, was markedly up-regulated by G-CSF in mice fed with ND and displayed strong positive correlation with widely scattered mobilization efficiency. It was hypothesized that BM fat ligand for PPARδ might inhibit mobilization. The PPARδ agonist inhibited mobilization in mice fed with ND and enhanced mobilization by FFD. Treatment with the PPARδ antagonist and chimeric mice with PPARδ+/- BM showed enhanced mobilization. Immunohistochemical staining and flow cytometry revealed that BM PPARδ expression was enhanced by G-CSF mainly in mature/immature neutrophils. BM lipid mediator analysis revealed that G-CSF treatment and FFD resulted in the exhaustion of ω3-polyunsaturated fatty acids such as eicosapentaenoic acid (EPA). EPA induced the up-regulation of genes downstream of PPARδ, such as carnitine palmitoyltransferase-1α and angiopoietin-like protein 4 (Angptl4), in mature/immature neutrophils in vitro and inhibited enhanced mobilization in mice fed with FFD in vivo. Treatment of wild-type mice with the anti-Angptl4 antibody enhanced mobilization together with BM vascular permeability. Collectively, PPARδ signaling in BM mature/immature neutrophils induced by dietary fatty acids negatively regulates mobilization, at least partially, via Angptl4 production.

FGF-23 from erythroblasts promotes hematopoietic progenitor mobilization

Fibroblast growth factor 23 (FGF-23) hormone is produced by bone-embedded osteocytes and regulates phosphate homeostasis in kidneys. We found that administration of granulocyte colony-stimulating factor (G-CSF) to mice induced a rapid, substantial increase in FGF-23 messenger RNA in bone marrow (BM) cells. This increase originated mainly from CD45-Ter119+CD71+ erythroblasts. FGF-23 protein in BM extracellular fluid was markedly increased during G-CSF-induced hematopoietic progenitor cell (HPC) mobilization, but remained stable in the blood, with no change in the phosphate level. Consistent with the BM hypoxia induced by G-CSF, low oxygen concentration induced FGF-23 release from human erythroblast HUDEP-2 cells in vitro. The efficient mobilization induced by G-CSF decreased drastically in both FGF-23-/- and chimeric mice with FGF-23 deficiency, only in hematopoietic cells, but increased in osteocyte-specific FGF-23-/- mice. This finding suggests that erythroblast-derived, but not bone-derived, FGF-23 is needed to release HPCs from BM into the circulation. Mechanistically, FGF-23 did not influence CXCL-12 binding to CXCR-4 on progenitors but interfered with their transwell migration toward CXCL-12, which was canceled by FGF receptor inhibitors. These results suggest that BM erythroblasts facilitate G-CSF-induced HPC mobilization via FGF-23 production as an intrinsic suppressor of chemoattraction.

Repeated social defeat stress induces neutrophil mobilization in mice: maintenance after cessation of stress and strain-dependent difference in response

BACKGROUND AND PURPOSE

Inflammation has been associated with stress-related mental disturbances. Rodent studies have reported that blood-borne cytokines are crucial for stress-induced changes in emotional behaviours. However, the roles and regulation of leukocytes in chronic stress remain unclear.

EXPERIMENTAL APPROACH

Adult male C57BL/6N mice were subjected to repeated social defeat stress (R-SDS) with two protocols which differed in stress durations, stress cycles, and housing conditions, followed by the social interaction test. The numbers of leukocyte subsets in the bone marrow, spleen, and blood were determined by flow cytometry shortly after or several days after R-SDS. These leukocyte changes were studied in two strains of mice with different stress susceptibility, C57BL/6N and BALB/c mice.

KEY RESULTS

R-SDS with both protocols similarly induced social avoidance in C57BL/6N mice. In the bone marrow, neutrophils and monocytes were increased, and T cells, B cells, NK cells, and dendritic cells were decreased with both protocols. In the blood, neutrophils and monocytes were increased with both protocols, whereas T cells, B cells, NK cells, and dendritic cells were decreased with one of these. Neutrophils and monocytes were also increased in the spleen. Changes in the bone marrow and increased levels of circulating neutrophils were maintained for 6 days after R-SDS. BALB/c mice showed greater social avoidance and increase in circulating neutrophils than C57BL/6N mice.

CONCLUSION AND IMPLICATIONS

In two strains of mice, chronic stress induced neutrophil mobilization and its maintenance. These effects were strain-related and may contribute to the pathology of mental illness.

LINKED ARTICLES

This article is part of a themed issue on Neurochemistry in Japan. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.4/issuetoc.

Bone: a key aspect to understand phenomena in clinical hematology

The bone marrow (BM) is located inside the bone. Now, it appears that bone tissue functionally communicates with the BM hematopoietic system. Osteoblast lineage cells serve as a part of the microenvironment for immature hematopoietic (stem/progenitor) cells. In contrast, mature hematopoietic cells such as neutrophils and macrophages play a critical role to regulate osteoblast activity. A progressive distortion of this precise inter-organ communication between hematopoietic and skeletal systems may lead to hematologic disorders. Recent studies have revealed that vitamin D receptor is a pivotal bridging molecule for this network and for the pathogenesis of myelofibrosis.

Transformed Follicular Lymphoma (TFL) Predicts Outcome in Advanced Endometrial Cancer

Background: Transformed follicular lymphoma (TFL, ZC3H12D) was identified as a candidate tumor suppressor gene that contributes to cell-cycle arrest through regulation of Rb phosphorylation, but the clinical impact of TFL is unknown. The goal of this study was to evaluate the prognostic significance of TFL expression in advanced endometrial cancer.Methods: Tissue samples were obtained from 103 patients with Federation Internationale des Gynaecologistes et Obstetristes stage III-IV endometrial cancer. Associations between TFL expression and outcomes were evaluated using the Kaplan-Meier method and multivariate Cox proportional hazards regression models.Results: There were 24 TFL-low cases (23.3%) and the 10-year progression-free survival (PFS) and overall survival (OS) in these cases were lower than those for patients with normal TFL expression in univariate analysis (PFS, P = 0.003; OS, P = 0.106). In multivariate analysis, TFL status was a significant predictor for PFS [HR = 2.76; 95% confidence interval (CI), 1.45-5.28; P = 0.002] and OS (HR = 1.94; 95% CI, 0.91-4.11; P = 0.085), adjusted for covariates. The TFL gene maps to human chromosome 6q25.1, where estrogen receptor alpha (ERα) gene ESR1 is also located. Lack of ERα expression is a poor prognostic factor in early endometrial cancer. Among 41 ERα-low patients, 10-year PFS was significantly lower in 15 TFL-low cases (univariate analysis, P = 0.055; multivariate analysis, HR = 4.70; 95% CI, 1.68-13.20; P = 0.003).Conclusions: We identified TFL as a strong independent prognostic factor, regardless of ERα status.Impact: An investigation of the mechanism underlying tumor suppression by TFL may lead to new therapies for patients with advanced endometrial cancer. Cancer Epidemiol Biomarkers Prev; 27(8); 963-9. ©2018 AACR.

[Thrombopoietin receptor agonists administration for acute exacerbation of chronic idiopathic thrombocytopenic purpura and subsequent anticoagulant therapy for accompanying deep venous thrombosis of the lower limbs]

We report two patients (70- and 49-year-old Japanese men) with acute exacerbation of chronic idiopathic thrombocytopenic purpura (ITP) and deep venous thrombosis of the lower extremities. Both were successfully managed with thrombopoietin receptor agonist (TPO-RA) administration. Both had ITP refractory to steroid treatment. Their immature platelet fraction (absolute-IPF) counts were increased and paralleled the platelet recoveries after TPO-RA (eltrombopag and romiplostim, respectively) without progression of thrombosis. Although ITP has recently been evaluated as a thrombophilic disorder, reports on acute exacerbation of ITP with newly diagnosed thrombosis are limited, and the pathophysiology and association between ITP and thrombosis remain to be elucidated. Moreover, the influences of TPO-RA on thrombosis are still controversial. To our knowledge, this is the first case report describing patients with exacerbation of ITP who developed thrombosis and were treated with TPO-RA. The outcomes of our cases underscore the importance of monitoring thrombosis and not delaying the initiation of anticoagulation treatment during the use of TPO-RA.

Posttranscriptional modulation of cytokine production in T cells for the regulation of excessive inflammation by TFL

Posttranscriptional machinery regulates inflammation and is associated with autoimmunity as well as tumorigenesis in collaboration with transcription factors. We previously identified the tumor suppressor gene transformed follicular lymphoma (TFL) on 6q25 in a patient with follicular lymphoma, which transformed into diffuse large B cell lymphoma. TFL families have a common RNase domain that governs macrophage-mediated inflammation. In human peripheral blood, TFL is dominantly expressed at the glycine- and tryptophan-rich cytoplasmic processing bodies of T lymphocytes, and it is persistently upregulated in activated T cells. To address its physiological role, we established TFL(-/-) mice in which TFL(-/-) lymphocytes proliferated more rapidly than TFL(+/+) upon stimulation with inappropriate cytokine secretion, including IL-2, IL-6, and IL-10. Moreover, TFL inhibited the synthesis of cytokines such as IL-2, IL-6, IL-10, TNF-α, and IL-17a by 3' untranslated region RNA degradation. Experimental autoimmune encephalitis induced in TFL(-/-) mice demonstrated persistent severe paralysis. CNS-infiltrated CD4(+) T cells in TFL(-/-) mice contained a higher proportion of Th17 cells than did those in TFL(+/+) mice during the resolution phase, and IL-17a mRNA levels were markedly increased in TFL(-/-) cells. These results suggest that TFL may play an important role in attenuating local inflammation by suppressing the infiltration of Th17 cells in the CNS during the resolution phase of experimental autoimmune encephalitis. TFL is a novel gradual and persistent posttranscriptional regulator, and the TFL-driven attenuation of excessive inflammation could contribute to recovery from T cell-mediated autoimmune diseases.

[Diminished expression of CD5 and/or CD7 surface antigens as the first clue of diagnosis for monoclonal T lymphocytosis]

The significance of precursor status for mature T-cell neoplasms has not been elucidated. Diagnosis of T-cell neoplasms is often challenging and sometimes overlooked when leukocytosis is not evident and neoplastic cell morphology is hardly distinguishable. Here, we report two cases of monoclonal T lymphocytosis (MTL) without evident lymphocytosis and lymphadenopathies that show slightly diminished CD5 and/or CD7 surface antigens as the first clue of diagnosis. Recently, some reports have demonstrated the possibility that monoclonal lymphocytosis precedes leukemia/lymphoma. Although its clinical significance is unknown, flow cytometric analysis of peripheral blood is useful for detection of occult MTL and careful follow-up is required.

Successful management of obstructive jaundice due to gallstones with eculizumab in a patient with paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) makes patients susceptible to intravascular hemolysis and thrombosis, and it can be life-threatening in stressful situations. Eculizumab, a humanized monoclonal antibody that inhibits the complement protein C5, has been evaluated as a novel therapy for PNH. We herein describe the case of a 59-year-old Japanese woman with classic PNH, who had been successfully treated with eculizumab, but who later developed acute cholecystitis/cholangitis from gallstones. Although the severe obstructive jaundice requiring endoscopic therapy following cholecystectomy was complicated, critical intravascular hemolysis and thrombosis were not observed. Therefore, utilizing eculizumab during the peri-operative management of PNH patients should be carefully taken into consideration.