Levels Of Flt3L Research Articles

Flt3L, a Cytokine and Growth Factor, Is Reduced in the Urine of Felines With Interstitial Cystitis

ObjectivesFeline idiopathic cystitis (FIC) is characterized by bladder pain with difficulties in urination and increased urinary frequency. It is one of the most common forms of Feline lower urinary tract disease (FLUTD). While the pathogenesis of FIC is not clear, inflammation plays a major role in its progression. We conducted a retrospective study to investigate whether cytokine levels change prior to the diagnosis of FIC, in order to identify a reliable non-invasive marker. MethodsWe assessed protein levels of inflammatory markers using ELISA in the blood and urine of cats clinically diagnosed with FIC (n = 6), FLUTD (n = 3), painful bladder (n = 13) as well as healthy controls (n = 23). Urine samples were obtained by cystocentesis. Mixed model/factorial analysis was performed by using JMP pro v15.0 with health conditions and the collection year of the samples as fixed effect and animal as random effect. ResultsMean urinary Fms-like tyrosine kinase 3 ligand (Flt3L) was significantly reduced in all cats with interstitial cystitis compared with healthy cats (39.9 vs 119.5 pg/ml respectively, P < 0.001). Interestingly, such lower levels of Flt3-L were observed in cats with cystitis at 4 to 5 years before the clinical diagnosis of cystitis. Conversely, Flt3L levels were higher in healthy cats over the same time period assessed in the study. Other cytokines including stem cell factor and IL12p40 were also significantly reduced in cats with cystitis compared with healthy cats. Flt3-L is a ligand for the receptor Flt3 that is expressed in hematopoietic progenitor cells, and is crucial for dendritic cell development and enhances lymphoid progenitor cells. Flt3L has been reported to have both pro-inflammatory and anti-inflammatory effects, but administration of Flt3L in human subjects increases the number of Treg cells and a subsequent reduction in inflammation. Surprisingly serum Flt3L level was not significantly different between cystitis and healthy cats although there was an increase in serum IL-18, a pro-inflammatory cytokine, when compared to controls (ns) ConclusionsOur results suggest that Flt3L level in urine may serve as a potential diagnostic biomarker for FIC. Nutritional interventions including polyphenols and antioxidants aimed at increasing levels of Flt3L may be important in mitigating the progression of cystitis in cats. Funding SourcesHills PNC.

DNGR-1 limits Flt3L-mediated antitumor immunity by restraining tumor-infiltrating type I conventional dendritic cells

BackgroundConventional type 1 dendritic cells (cDC1s) are central to antitumor immunity and their presence in the tumor microenvironment associates with improved outcomes in patients with cancer. DNGR-1 (CLEC9A) is a...

The Impact of Sorafenib on Phospho-FLT3 Inhibition and FLT3-ITD MRD after Chemotherapy: Correlative Studies from the Phase 2 Randomized Study of Sorafenib Versus Placebo in Combination with Intensive Chemotherapy in Previously Untreated Patients with FLT3-ITD Acute Myeloid Leukemia (ALLG AMLM16)

The Impact of Sorafenib on Phospho-FLT3 Inhibition and FLT3-ITD MRD after Chemotherapy: Correlative Studies from the Phase 2 Randomized Study of Sorafenib Versus Placebo in Combination with Intensive Chemotherapy in Previously Untreated Patients with FLT3-ITD Acute Myeloid Leukemia (ALLG AMLM16)

Mesenchymal stem cell therapy induces FLT3L and CD1c+ dendritic cells in systemic lupus erythematosus patients

Allogeneic mesenchymal stem cells (MSCs) exhibit immunoregulatory function in human autoimmune diseases such as systemic lupus erythematosus (SLE), but the underlying mechanisms remain incompletely understood. Here we show that the number of peripheral tolerogenic CD1c+ dendritic cells (DCs) and the levels of serum FLT3L are significantly decreased in SLE patients especially with lupus nephritis, compared to healthy controls. Transplantation of allogeneic umbilical cord-derived MSCs (UC-MSCs) significantly up-regulates peripheral blood CD1c+DCs and serum FLT3L. Mechanistically, UC-MSCs express FLT3L that binds to FLT3 on CD1c+DCs to promote the proliferation and inhibit the apoptosis of tolerogenic CD1c+DCs. Conversely, reduction of FLT3L with small interfering RNA in MSCs abolishes the up-regulation of tolerogenic CD1c+DCs in lupus patients treated with MSCs. Interferon-γ induces FLT3L expression in UC-MSCs through JAK/STAT signaling pathway. Thus, allogeneic MSCs might suppress inflammation in lupus through up-regulating tolerogenic DCs.

The FMS-like tyrosine kinase-3 ligand/lung dendritic cell axis contributes to regulation of pulmonary fibrosis

RationaleDendritic cells (DC) accumulate in the lungs of patients with idiopathic lung fibrosis, but their pathogenetic relevance is poorly defined.ObjectivesTo assess the role of the FMS-like tyrosine kinase-3 ligand (Flt3L)-lung...

The Prognostic Value of Serum Cytokines in Patients with Acute Ischemic Stroke.

The inflammatory response is an unavoidable process and contributes to the destruction of cerebral tissue during the acute ischemic stroke (AIS) phase and has not been addressed fully to date. Insightful understanding of correlation of inflammatory mediators and stroke outcome may provide new biomarkers or therapeutic approaches for ischemic stroke. Here, we prospectively recruited 180 first-ever AIS patients within 72 hrs after stroke onset. We used the National Institutes of Health Stroke Scale (NIHSS) to quantify stroke severity and modified Rankin scale (mRS) to assess the 3-month outcome for AIS patients. Initially, we screened 35 cytokines, chemokines, and growth factors in sera from 75 AIS patients and control subjects. Cytokines that were of interest were further investigated in the 180 AIS patients and 14 heathy controls. We found that IL-1RA, IL-1β, IL-4, IL-5, IL-6, IL-7, IL-9, IL-10, IL-13, IL-15, EGF, G-CSF, Flt-3L, GM-CSF and Fractalkine levels were significantly decreased in severe stroke patients. In particular, IL-1β, IL-4, IL-5, IL-7, IL-9, IL-10, IL-15, G-CSF and GM-CSF were significantly reduced in AIS patients with poor outcome, compared to those with good prognosis. IL-6 was notably higher in the poor outcome group. Only IL-9 level decreased in the large infarct volume group. After adjusting for confounders, we found that IL-5 was an independent protective factor for prognosis in AIS patients with an adjusted OR of 0.042 (P = 0.007), whereas IL-6 was an independent risk predictor for AIS patients with an adjusted OR of 1.293 (P = 0.003). Our study suggests the levels of serum cytokines are related to stroke severity, short-term prognosis and cerebral infarct volume in AIS patients.

ICOSL+ Plasmacytoid Dendritic Cells As Biomarker and Inducer of Graft-Versus-Host Disease

Acute graft-versus-host disease (GVHD) remains one of the leading causes of death post allogeneic hematopoietic cell transplantation (HCT). Gastrointestinal GVHD (GI-GVHD), the most fatal type of GVHD, would benefit from additional biomarkers that are therapeutic targets. Using state-of-the-art quantitative proteomics we previously identified and validated an increased CD4+CD146+ T cell population in GI-GVHD patients. This population expressed a Th1 and Th17 phenotype and was induced by Inducible COStimulator (ICOS), a critical costimulatory molecule for the development of pathogenic Th17 (Li W. et al, J. Clin. Invest. Insights, 2016).ICOS binds its ligand, ICOSL, which is expressed on dendritic cells (DCs) that prime naïve T cells to initiate immune responses. This prompted us to examine ICOSL expression on the two blood DCs subsets that can be identified in human peripheral blood: Lineage-HLADR+CD11c+ myeloid DCs (mDCs) and Lineage-HLADR+CD123+ plasmacytoid DCs (pDCs). Using the same cohort of patients aforementioned, the frequency of ICOSL was significantly higher on pDCs in 64 GI-GVHD patients when compared to 22 non-GVHD enteritis patients, 35 skin GVHD patients, and 39 patients without GVHD (Figure 1). The numbers and frequencies of total DCs, mDCs and pDCs were similar between groups.The growth factor fms-related tyrosine kinase 3 ligand (Flt3l) is necessary for the development and differentiation of pDCs, and the transcription factor, Stat3, is required for Flt3l-dependent dendritic cell differentiation in mice. The role of pDCs in acute GVHD is still controversial (tolerogenic or initiator of GVHD depending on the murine model), and confirmatory studies about their functions are necessary before a therapeutic approach based on this mechanism can be contemplated. Based on the patients' data and previous knowledge, we hypothesized that absence of ICOSL signaling in donor DCs would protect against GVHD through Flt3l, Stat3, or both. We first found that knocking out (KO) ICOSL in the donor bone marrow (BM) extended survival compared to wild-type (WT) mice in the major mismatch (B6, H-2b à BALB/c, H-2d) experimental HCT model, while recipients of Stat3KO BM did not show any difference in GVHD mortality (Figure 2A). We also found a significant decrease of Flt3l levels in plasma collected at day 3 from ICOSLKO BM recipients compared to WT mice (Figure 2B). We then analyzed the recipients' infiltrating intestinal immune cells at day 10 post-HCT for the infiltration of pDCs and pathogenic Th17 cells. We found significantly lower frequencies of intestinal pDCs (CD11b-CD11c+B220+CD103+) (Figure 2C), and intestinal T cells coexpressing interferon (IFN)g and IL-17 (Figure 2D) in recipients of ICOSLKO BM compared to recipients of WT BM. Absolute counts of these two populations followed the same trend (data not shown). To confirm these data were not strain-specific, we performed similar analyses in the haplo-identical (B6, H-2b à B6D2F1, H-2d) experimental model showing similar outcomes for pDCs and IFNγ+IL-17+ T cells frequencies and counts in recipients of ICOSLKO BM compared to recipients of WT BM. Importantly, and in contrast to human T cells, CD146 is not expressed on naïve murine T cells and thus cannot be measured in vivo in acute GVHD models. Transcriptome analyses by Nanostring technology (Immunology panels) comparing 14 days post-HCT of sorted pDCs from ICOSLKO BM versus WT haplo-identical recipients showed increased expression of key molecules required for development (Itgax, Nos2, Socs1, Tcf4 and Bst2), costimulation (Cd80, Cd48, Cd74 and Cd86), and function (Tyrobp, Ikbkg, Nod2 and Irf7) of pDCs (Figure 3A). Lastly, we found increased T cell activation markers including Prf1, Il17a, eomes in sorted CD4+ T cells from ICOSLKO BM compared to WT recipients (Figure 3B).We conclude that early quantification of ICOSL+ pDCs frequency may allow identification of patients at risk of GI-GVHD development. Targeting ICOSL may represent a new avenue to treat acute GVHD. [Display omitted] DisclosuresPaczesny:Viracor IBT Laboratories: Patents & Royalties.

Abstract A43: Induction of systemic immune response by oxaliplatin-based neoadjuvant therapy and survival without metastatic progression in high-risk rectal cancer

Abstract In locally advanced rectal cancer (LARC), local recurrence rates are low due to contemporary multimodal treatment regimens involving neoadjuvant chemoradiotherapy (CRT) and surgery. Metastatic progression however, represents a major challenge and is reported by 30-40% of cases in recent trials. Ongoing effort to combine treatment modalities, including immunotherapy, to best target systemic progression of colorectal cancer, would benefit from a better understanding of the biological and immune responses invoked from the different treatment modalities. In this report we investigated systemic immune activity invoked in LARC patients undergoing neoadjuvant regimens containing oxaliplatin (an agent known to cause immunogenic cell death), by assessing circulating levels of the fms-related tyrosine kinase 3 ligand (Flt3L). Flt3L is a potent hematopoietic factor with proliferating effects on mature dendritic cells (DC), whose elevated levels have also been demonstrated to reflect therapy-induced myelosuppression. LARC patients with mainly T3-4 disease from two independent cohorts (Oslo and Copenhagen) received neoadjuvant chemotherapy (NACT) and sequential CRT. All of the Oslo cohort patients underwent NACT consisting of 4 weeks of the Nordic FLOX regimen (oxaliplatin 85 mg/m2 on day 1 and bolus fluorouracil 500 mg/m2 and folinic acid 100 mg on days 1 and 2 every second week) followed by long-course CRT (radiation to a total dose of 50 Gy and concomitant weekly oxaliplatin 50 mg/m2 and capecitabine 825 mg/m2 twice daily), and then surgery 8-12 weeks later. Eighty percent of Copenhagen cohort patients underwent NACT as 6-8 weeks of oxaliplatin 85 mg/m2 every second week and continuous capecitabine 650 mg/m2 twice daily. Less than 90% of patients had concomitant weekly oxaliplatin 50 mg/m2 during the long-course CRT to a total radiation dose of 54 Gy. Finally, 57% of patients received an additional 1-2 cycles of capecitabine with or without oxaliplatin following CRT completion. Patients had surgery 2-19 weeks after CRT completion. In both cohorts, Flt3L levels were measured in serum collected at baseline, following NACT and then the sequential CRT. Serum samples were stored at –80°C until analysis and Flt3L was quantified using ELISA or a customized Luminex Multiplex Assay (both from R&amp;D Systems). In 39 randomly chosen samples covering all three sampling points, a strong correlation (r=0.96, p&amp;lt;0.01) was found between Flt3L levels measured by the single-parameter and multiplex assays. We found that median serum Flt3L levels were elevated upon completion of each sequential modality in both cohorts (n=73 and n=65). In the principal cohort (Oslo), an increase in levels of Flt3L upon NACT completion was correlated with a decline in hemoglobin and neutrophil counts (r=–0.38, p&amp;lt;0.01 and r= –0.36, p=0.01), possibly reflecting the myelosuppressive effect. Progression-free survival (PFS), with the majority of events being metastatic progression, was 68% and 71% in the two cohorts. For T4 cases in the Oslo cohort, a high Flt3L level following NACT was associated with a low risk for a PFS event (HR=0.22, 95% CI=0.06-0.72, p=0.01). Additionally, oxaliplatin dose reduction during CRT, aimed at maintaining patient compliance to radiotherapy, was also associated with advantageous PFS (HR=0.40, 95% CI=0.17-0.92, p=0.03). In conclusion, the neoadjuvant regimens might have caused repetitive myelosuppression resulting in elevated circulating Flt3L levels, thereby enhancing proliferation of mature dendritic cells and mediation of systemic tumor-targeting effects. Oxaliplatin-containing neoadjuvant therapy that causes normal tissue toxicity but does not compromise patient compliance to the radiotherapy, may condition DC to present shed tumor antigens to cytotoxic T cells, and thus enable eradication of occult microscopic tumor at distant sites in LARC patients prone to develop metastatic disease. Citation Format: Erta Kalanxhi, Sebastian Meltzer, Jakob Vasehus Schou, Finn Ole Larsen, Svein Dueland, Kjersti Flatmark, Benny Vittrup Jensen, Knut Håkon Hole, Therese Seierstad, Kathrine Røe Redalen, Dorte Lisbet Nielsen, Anne Hansen Ree. Induction of systemic immune response by oxaliplatin-based neoadjuvant therapy and survival without metastatic progression in high-risk rectal cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr A43.

Abstract CT008: A pilot trial of the combination of transgenic NY-ESO-1-reactive adoptive cellular therapy with dendritic cell vaccination with or without ipilimumab in patients with sarcoma and melanoma

Abstract Background: Transgenic adoptive cell therapy (ACT) targeting the tumor antigen NY-ESO-1 can be effective for the treatment of sarcoma and melanoma. Preclinical models have shown that this therapy can be improved with the addition of dendritic cell (DC) vaccination and immune checkpoint blockade. In this study, we report the results of the safety, feasibility, and antitumor efficacy of this approach alone and in combination with the CTLA-4 blockade with ipilimumab. Methods: NY-ESO-1 specific T-cell receptor (TCR) transgenic lymphocytes were adoptively transferred together with NY-ESO-1 peptide-pulsed DC vaccination in HLA-A*0201-positive subjects with (ESO, NCT02070406) or without ipilimumab (INY, NCT01697527) in patients with advanced sarcoma and melanoma under Investigator New Drug IND#15167. Patients received autologous retrovirally TCR-transduced T cells following a lymphodepleting preparative chemotherapy regimen. NY-ESO-1157-165 peptide-pulsed autologous DCs were administered on Days 1, 14 and 30, and low-dose IL-2 was given twice daily for 7-14 days. In the INY cohort, ipilimumab (1mg/kg) was given on day 0 or 1, and every three weeks for a maximum of four doses. Response rates were evaluated by RECIST. Results: Four patients with synovial sarcoma, two patients with melanoma, one patient with osteosarcoma, one patient with liposarcoma, and one patient with malignant peripheral nerve sheath tumor were enrolled into these cohorts. Two patients (one treated per ESO, and another treated per INY) experienced cytokine release syndrome requiring hospitalization. Patients treated per INY had significantly higher serum levels of the cytokine FLT-3L. Two out of four patients treated per INY, and four out of six patients treated per ESO demonstrated an objective clinical response by day 30. One patient treated per ESO (17%) has had an ongoing complete response for 3 years. One patient was treated per ESO and, following disease progression after an objective clinical response, was subsequently enrolled in INY. TCR sequencing of dextramer-positive cells demonstrated that the NY-ESO TCR integrated across a highly polyclonal population of endogenous TCR clonotypes. Tracking of transgenic T cells to the tumor and acquisition of PD-1 expression was demonstrated by TCR sequencing and immunohistochemistry of on-treatment biospies, respectively. Conclusions: ACT of fresh NY-ESO-1 transgenic T cells prepared via a short ex vivo protocol and given with DC vaccination and low dose IL-2, with or without ipilimumab, is feasible and results in transient antitumor activity, with no apparent clinical benefit of the addition of ipilimumab. Improvements are needed to maintain tumor responses. Citation Format: Theodore S. Nowicki, Beata Berent-Maoz, Rong Rong Huang, Xiaoyan Wang, Gardenia Cheung-Lau, Paula Kaplan-Lefko, Paula Cabrera, Justin Tran, Ignacio Baselga Carretero, Catherine S. Grasso, Siwen Hu-Lieskovan, Bartosz Chmielowski, Begoña Comin-Anduix, Arun Singh, Antoni Ribas. A pilot trial of the combination of transgenic NY-ESO-1-reactive adoptive cellular therapy with dendritic cell vaccination with or without ipilimumab in patients with sarcoma and melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT008.

Nlrp3-dependent IL-1β inhibits CD103+ dendritic cell differentiation in the gut.

Inflammatory bowel disease (IBD) is associated with enhanced levels of the IL-1 family cytokines IL-1β and IL-18, which are activated by the Nlrp3 inflammasome. Here, we investigated the role of inflammasome-driven cytokine release on T cell polarization and DC differentiation in steady state and T cell transfer colitis. In vitro and in vivo data showed that IL-1β induces Th17 polarization and increases GM‑CSF production by T cells. Reduced IL-1β levels in Nlrp3-/- mice correlated with enhanced FLT3L levels and increased frequency of tolerogenic CD103+ DC. In the T cell transfer colitis model, Nlrp3 deficiency resulted in lower IL‑1β levels, reduced Th17 immunity, and less severe colitis. Unaltered IL-18 levels in both mouse strains pointed toward Nlrp3-independent processing. Importantly, cohousing revealed that the gut microbiome had no impact on the observed Nlrp3-/- phenotype. This study demonstrates that NLRP3 acts as a molecular switch of intestinal homeostasis by shifting local immune cells toward an inflammatory phenotype via IL-1β.

Flt3 ligand expands bona fide innate lymphoid cell precursors in vivo

A common helper-like innate lymphoid precursor (CHILP) restricted to the innate lymphoid cells (ILC) lineage has been recently characterized. While specific requirements of transcription factors for CHILPs development has been partially described, their ability to sense cytokines and react to peripheral inflammation remains unaddressed. Here, we found that systemic increase in Flt3L levels correlated with the expansion of Lineage (Lin)negα4β7+ precursors in the adult murine bone marrow. Expanded Linnegα4β7+ precursors were bona fide CHILPs as seen by their ability to differentiate into all helper ILCs subsets but cNK in vivo. Interestingly, Flt3L-expanded CHILPs transferred into lymphopenic mice preferentially reconstituted the small intestine. While we did not observe changes in serum Flt3L during DSS-induced colitis in mice or plasma from inflammatory bowel disease (IBD) patients, elevated Flt3L levels were detected in acute malaria patients. Interestingly, while CHILP numbers were stable during the course of DSS-induced colitis, they expanded following increased serum Flt3L levels in malaria-infected mice, hence suggesting a role of the Flt3L-ILC axis in malaria. Collectively, our results indicate that Flt3L expands CHILPs in the bone marrow, which might be associated with specific inflammatory conditions.

High levels of FLT3-ligand in bone marrow and peripheral blood of patients with advanced multiple myeloma.

IntroductionMultiple myeloma (MM) is still incurable due to resistance against various therapies. Thus, the identification of biomarkers predicting progression is urgently needed. Here, we evaluated four biomarkers in bone marrow and peripheral blood of MM patients for their prognostic significance.Materials & methodsBone marrow- and peripheral blood plasma levels of FLT3-L, soluble TIE2, endostatin, and osteoactivin were determined in patients with monoclonal gammopathy of undetermined significance (MGUS, n = 14/n = 4), patients with newly diagnosed MM (NDMM, n = 42/n = 31) and patients with relapsed/refractory MM (RRMM, n = 27/n = 16) by sandwich ELISA.ResultsMedian FLT3-L expression increased from MGUS (58.77 pg/ml in bone marrow; 80.40 pg/ml in peripheral blood) to NDMM (63.15 pg/ml in bone marrow; 85.05 pg/ml in peripheral blood) and was maximal in RRMM (122 pg/ml in bone marrow; 160.47 pg/ml in peripheral blood; NDMM vs. RRMM p<0.001). A cut-off value of FLT3-L >92 pg/ml in bone marrow and >121 pg/ml in peripheral blood was associated with relapse or refractoriness in MM patients. FLT3-L was found to be a high predictive marker for discrimination between NDMM and RRMM as well in bone marrow as in peripheral blood (AUC 0.75 in bone marrow; vs 0.84 in peripheral blood).ConclusionHigh levels of FLT3-L in bone marrow and peripheral blood of MM patients identify patients with progressive disease and are associated with relapse or refractoriness in MM patients. FLT3-L could be useful as a marker to identify RRMM patients and should be evaluated as target for future therapies.

Serum Levels of Soluble FLT3 Ligand in Patients with Active Multiple Myeloma Constitute Marker of Bone Marrow Plasma Cell Proliferative Activity.

The FLT3-ligand is a molecule implicated in hematopoiesis. The aim of the present study was to detect any possible connections between serum levels of FLT3-L and multiple myeloma (MM) proliferation markers, such as serum levels of interleukin-6 (IL-6), B-cell activating factor (BAFF), beta-2 microglobulin (B2M), CRP and LDH, as well the percentage of bone marrow infiltration and the plasma cells' proliferation marker Ki-67 PI. We measured the above parameters in 58 patients with active MM. All circulating markers were significantly higher in MM patients compared to controls (p < 0.001 for all cases), and all values were increasing in parallel with disease stage (p < 0.001 for all cases). Positive correlations between FLT3-L were noted with serum levels of BAFF (p < 0.003), IL-6 (p < 0.002), CRP (p < 0.0001), LDH (p < 0.001), and BM Ki-67 PI (p = 0.012), whereas only trends of correlation were noted with the B2M value and the percentage of infiltration. It seems that the increased serum levels of circulating FLT3-L, in parallel with MM activity, reflect their increased presence in the bone marrow microenvironment, probably as an effect of increased angiogenesis and myelosuppression. Consequently, they are potential markers of disease activity.

Maternal and neonatal Fms-like tyrosine kinase 3 ligand (Flt-3L) levels: Modulation of neonatal immune maturity and childhood immune diseases

Maternal and neonatal Fms-like tyrosine kinase 3 ligand (Flt-3L) levels: Modulation of neonatal immune maturity and childhood immune diseases

Maternal and neonatal Fms-like tyrosine kinase 3 ligand (Flt-3L) levels: Modulation of neonatal immune maturity and childhood immune diseases

Maternal and neonatal Fms-like tyrosine kinase 3 ligand (Flt-3L) levels: Modulation of neonatal immune maturity and childhood immune diseases

Gamma-Tocotrienol Modulates Radiation-Induced MicroRNA Expression in Mouse Spleen.

Ionizing radiation causes depletion of hematopoietic cells and enhances the risk of developing secondary hematopoietic malignancies. Vitamin E analog gamma-tocotrienol (GT3), which has anticancer properties, promotes postirradiation hematopoietic cell recovery by enhancing spleen colony-forming capacity, and provides protection against radiation-induced lethality in mice. However, the underlying molecular mechanism involved in GT3-mediated postirradiation survival is not clearly understood. Recent studies have shown that natural dietary products including vitamin E provide a benefit to biological systems by modulating microRNA (miR) expression. In this study, we show that GT3 differentially modulates the miR footprint in the spleen of irradiated mice compared to controls at early times (day 1), as well as later times (day 4 and 15) after total-body irradiation. We observed that miR expression was altered in a dose- and time-dependent manner in GT3-pretreated spleen tissues from total-body irradiated mice. GT3 appeared to affect the expression of a number of radiation-modulated miRs known to be involved in hematopoiesis and lymphogenesis. Moreover, GT3 pretreatment also suppressed the upregulation of radiation-induced p53, suggesting the function of GT3 in the prevention of radiation-induced damage to the spleen. In addition, we have shown that GT3 significantly reduced serum levels of Flt3L, a biomarker of radiation-induced bone marrow aplasia. Further in silico analyses of the effect of GT3 implied the association of p38 MAPK, ERK and insulin signaling pathways. Our study provides initial insight into the mechanism by which GT3 mediates protection of spleen after total-body irradiation.

Stromal-Derived Factor-1α and Interleukin-7 Treatment Improves Homeostatic Proliferation of Naïve CD4+ T Cells after Allogeneic Stem Cell Transplantation

Graft-versus-host disease (GVHD) impairs immune reconstitution after allogeneic stem cell transplantation (allo-SCT) and effective therapies aimed at restoring T cell counts in GVHD patients have yet to be developed. During GVHD, CD4+ T cell reconstitution is particularly affected and current models hold that GVHD insult to the peripheral lymphoid niche is responsible for this effect. Here, we show that naïve CD4+ T cell homeostatic proliferation (HP) is lost during GVHD because of low systemic IL-7 and impaired dendritic cell (DC) regeneration. We assessed factors involved in DC differentiation and found that although fms-like tyrosine kinase 3 ligand (Flt3-L) levels were normal, stromal-derived factor-1α (SDF-1α) was diminished in the blood of GVHD mice. Unlike Flt3-L treatment, the administration of SDF-1α specifically increased CD8α+ DC numbers and did not worsen GVHD. Importantly, CD4+ T cell HP was enhanced only when IL-7 and SDF-1α or Flt3L were coadministered, confirming the crucial role of DCs and IL-7 in restoring CD4+ T cell regeneration during GVHD. Altogether, our results indicate that CD8α+ DCs are part of the peripheral niche that controls CD4+ T cell HP and that their depletion, combined with low systemic IL-7, explains how GVHD constrains naïve CD4+ T cell reconstitution after allo-SCT.

CSF Neurofilament Light Chain but not FLT3 Ligand Discriminates Parkinsonian Disorders.

The differentiation between multiple system atrophy (MSA) and Parkinson’s disease (PD) is difficult, particularly in early disease stages. Therefore, we aimed to evaluate the diagnostic value of neurofilament light chain (NFL), fms-like tyrosine kinase ligand (FLT3L), and total tau protein (t-tau) in cerebrospinal fluid (CSF) as biomarkers to discriminate MSA from PD. Using commercially available enzyme-linked immunosorbent assays, we measured CSF levels of NFL, FLT3L, and t-tau in a discovery cohort of 36 PD patients, 27 MSA patients, and 57 non-neurological controls and in a validation cohort of 32 PD patients, 25 MSA patients, 15 PSP patients, 5 CBS patients, and 56 non-neurological controls. Cut-offs obtained from individual assays and binary logistic regression models developed from combinations of biomarkers were assessed. CSF levels of NFL were substantially increased in MSA and discriminated between MSA and PD with a sensitivity of 74% and specificity of 92% (AUC = 0.85) in the discovery cohort and with 80% sensitivity and 97% specificity (AUC = 0.94) in the validation cohort. FLT3L levels in CSF were significantly lower in both PD and MSA compared to controls in the discovery cohort, but not in the validation cohort. t-tau levels were significantly higher in MSA than PD and controls. Addition of either FLT3L or t-tau to NFL did not improve discrimination of PD from MSA above NFL alone. Our findings show that increased levels of NFL in CSF offer clinically relevant, high accuracy discrimination between PD and MSA.

Rapid Exercise-Induced Mobilization of Dendritic Cells Is Potentially Mediated by a Flt3L- and MMP-9-Dependent Process in Multiple Sclerosis.

In healthy individuals, one exercise bout induces a substantial increase in the number of circulating leukocytes, while their function is transiently suppressed. The effect of one exercise bout in multiple sclerosis (MS) is less studied. Since recent evidence suggests a role of dendritic cells (DC) in the pathogenesis of MS, we investigated the effect of one combined endurance/resistance exercise bout on the number and function of DC in MS patients and healthy controls. Our results show a rapid increase in the number of DC in response to physical exercise in both MS patients and controls. Further investigation revealed that in particular DC expressing the migratory molecules CCR5 and CD62L were increased upon acute physical activity. This may be mediated by Flt3L- and MMP-9-dependent mobilization of DC, as demonstrated by increased circulating levels of Flt3L and MMP-9 following one exercise bout. Circulating DC display reduced TLR responsiveness after acute exercise, as evidenced by a less pronounced upregulation of activation markers, HLA-DR and CD86, on plasmacytoid DC and conventional DC, respectively. Our results indicate mobilization of DC, which may be less prone to drive inflammatory processes, following exercise. This may present a negative feedback mechanism for exercise-induced tissue damage and inflammation.

Protein biomarkers for enhancement of radiation dose and injury assessment in nonhuman primate total-body irradiation model.

Development and validation of early-response radiation injury biomarkers are critical for effective triage and medical management of irradiated individuals. Plasma protein and haematological profiles were evaluated using multivariate linear-regression analysis to provide dose-response calibration curves for photon-radiation dose assessment in 30 rhesus macaques total-body-irradiated to 1-8.5 Gy with (60)Co gamma rays (0.55 Gy min(-1)). Equations for radiation dose received were established based on different combinations of protein biomarkers [i.e. C-reactive protein (CRP), serum amyloid A (SAA), interleukin 6 (IL-6) and Flt3 Ligand (Flt3L)] at samples collection time-points 6 h, 1, 2, 3, 4 and 7 d post-total-body irradiation. Dynamic changes in the levels of CRP, SAA, IL-6 and Flt3L may function as prognostic indicators of the time course and severity of acute radiation sickness (ARS). The combination of protein biomarkers provides greater accuracy for early radiation assessment than any one biomarker alone.