FLT3 Ligand Levels Research Articles

A four-cell pathway orchestrated by Flt3-L-dependent cDCs controls anti-tumor responses

A study by Régnier etal. shows that Flt3-ligand (FL) levels program two distinct mechanisms of anti-tumor immunity. Low FL levels allow recruitment of T effectors and Tcell-mediated responses whereas high FL levels support recruitment of classical dendritic cells (cDC) and natural killer (NK) cells and NK-mediated anti-tumor responses.

FLT3 Ligand Kinetic Profile Predicts Response to Treatment and Event-Free Survival (EFS) in Adults with High-Risk MDS/CMML Receiving CPX-351: A GFM Study

Background: Our group recently reported, in a prospective multicentre phase 2 study of 31 patients with higher-risk (HR)-MDS or CMML receiving CPX-351 as first-line induction treatment 87% of overall responses (including 64.5% of CR/ CR according to ELN2017 criteria), and 93.5% of the patients could be bridged to transplant (GFM-CPX MDS trial, Peterlin et al. Lancet Haematol 2023). We had also previously reported, in AML, that the soluble forms of FLT3 ligand (FL) and IL6 could be prognostic factors of refractoriness to chemotherapy and overall survival (OS) (Peterlin et al. Cancer Medicine, 2021). A secondary objective of the GFM-CPX MDS trial was to assess the prognostic value of these two cytokines in HR-MDS/CMML receiving CPX-351. Methods: All patients included in the GFM-CPX MDS trial (clinicaltrials.gov#NCT04273802), induction chemotherapy with CPX-351 (44 mg Daunorubicin/100 mg Aracytine/m 2 on days 1, 3, and 5) also consented for the present biological FLAM-MDS sub-study. Using a new cytokine multiplex assay from Milliplex (MILLIPLEX®), FL levels (expressed in pg/mL) were evaluated on Day (D) 1, D8, D15 and D22 of the first cycle of induction; IL-6 (expressed in pg/mL) and CRP (known to be correlated with IL6, expressed in mg/L, normal value 0-5) levels were evaluated on D1 and D22 only. Patients who failed to achieve response (CR or CRi or MLFS, ELN2017 criteria) after the first induction cycle could receive a second one. The impact on CR/CRi rate after one cycle of CPX-351, OS and EFS of FL, IL-6 and CRP dosages and their kinetic profile during this first cycle were studied. Results: Dosages could be performed in 28 of the 31 patients included ( Table 1). Overall response (CR+CRi+MLFS) after cycle 1 was achieved in 24 (87%, MLFS n=7, CR+CRi n=17) patients; 3/4 non-responders received a second induction (1 achieved CR). Allograft was performed in 26/28 (93%). With a median follow-up of 18 months for surviving patients, 1y and 18-month OS were 79% and 75%, respectively. 1y and 18-month EFS were both 76%, respectively. Achieving CR/CRi versus MLFS/non-response was associated with better 1-y EFS (71% (52-96) vs 27% (10-72), p=0.009) but not 1-y OS (82% (66-100) vs 73% (51-100), p=0.8). Median (range) FL levels were 4.5 [0- 33.5] on D1, 74.1 [4.1-296.6] at D8, 326.6 [47.4-678] at D15 and 381.3 [4.4-800.1] at D22. As in AML (Peterlin et al, 2021), patients could be categorized according to three FLc kinetic profiles: i) sustained increase from D 1 to 22 (FLI group n=17, 61% of the cohort), ii) increase from D 1 to 15, then decrease on D 22 (FLD group, n=9, 32% of the cohort) and iii) persistent low levels (<100 pg/mL from D 1 to 22, FLL group, n=2, 7% of the cohort). Median (range) IL6 levels were 11 (0-587.8) on D1 and 179.8 (0-531) on D22. Increase of IL6 levels between D1 and D22 was observed in 19 patients (68%) and decrease in 7, while 2 patients had no IL6 detectable at either times. Finally, median (range) CRP levels were 2.3 (0-108) on D1 and 40.5 (7.2-323) on D22. Increase of CRP level was observed in most patients between D1 and D22 (n=25, 96%). There was no correlation between IL6 and CRP levels on D1 (p=0.64) or D22 (p=0.48). CR/CR rates, 1-y OS and EFS were not correlated with FL levels (< vs > median) at the 4 time points considered. However, a FLD kinetic profile was significantly associated with higher CR/CRi rates (100% vs FLI 47% vs FLL 50%, p=0.002) and 1-y EFS (78% (55-100) vs FLI 47% (28-78) vs FLL: 0%, p=0.003), Figure 1). 1-y OS was similar between the 3 FL kinetic profile groups (FLD: 89% (71-100) vs FLI 76% (59-100) vs FLL 50% (13-100), p=0.7)). In multivariate analysis, taking into account age, gender, R-IPSS and the FL kinetic profile during cycle 1 of CPX-351, a FLD kinetic profile was the only factor associated with higher CR/CRi rate (OR: 24.2, 95%CI: 2.4-3278, p=0.004) and better EFS (OR: 21.91; 95%CI: 2.47-194.77, p=0.006). Levels and kinetic profiles of IL6 and CRP had no impact on CR/CRi rates, OS and EFS. Conclusion: As in AML, FL kinetic profile predicts response and survival in HR-MDS/CMML. A FLD kinetic profile was the only factor independently associated with higher CR/CRi rates and better EFS. These results have to be confirmed on larger cohorts. Other treatment approaches may be of interest in patient with a non FLD profile.

Effects of repeated binge intake of the pyrovalerone cathinone derivative 3,4-methylenedioxypyrovalerone on prefrontal cytokine levels in rats - a preliminary study.

Drugs of abuse activate neuroimmune signaling in addiction-related regions of the brain, including the prefrontal cortex (PFC) which mediates executive control, attention, and behavioral inhibition. Traditional psychostimulants including methamphetamine and cocaine are known to induce PFC inflammation, yet the effects of synthetic cathinone derivatives are largely unexplored. In this study, we examined the ability of repeated binge-like intake of the pyrovalerone cathinone derivative 3,4-methylenedioxypyrovalerone (MDPV) to alter cytokine profiles in the PFC. Male and female rats were allowed to intravenously self-administer MDPV (0.05 mg/kg/infusion) or saline as a control under conditions of prolonged binge-like access, consisting of three 96 h periods of drug access interspersed with 72 h of forced abstinence. Three weeks following cessation of drug availability, PFC cytokine levels were assessed using antibody arrays. Employing the unsupervised clustering and regression analysis tool CytoMod, a single module of co-signaling cytokines associated with MDPV intake regardless of sex was identified. With regards to specific cytokines, MDPV intake was positively associated with PFC levels of VCAM-1/CD106 and negatively associated with levels of Flt-3 ligand. These findings indicate that prolonged MDPV intake causes changes in PFC cytokine levels that persist into abstinence; however, the functional ramifications of these changes remain to be fully elucidated.

High-Risk Cytokine Profiles Predict Lower Survivals in AML after Allotransplantation

Introduction: In a context of allogeneic hematopoietic stem cell transplantation (Allo-HSCT) for acute myeloid leukemia (AML), the impact of peripheral cytokine levels has been poorly studied so far. Methods: The aim of this prospective study (NCT02693899) was to analyze peripheral levels of 8 cytokines in 35 AML patients (pts) before conditioning (BC) then at Day (D) 0, 30, 60 and 100 post-Allo-HSCT by comparison to median levels from 20 healthy controls (16 males, median age 48.5 yo). ELISA (Bio-Techne, Minneapolis, MN) was used to assay the levels of FLt3-ligand (FL), TNF-alpha, stem-cell factor (SCF), c-kit, IL-1 beta, IL-6, IL-10 and granulocyte-monocyte colony-stimulating factor (GM-CSF). A total of 1313 and 157 samples were analyzed in pts and controls, respectively. The impact of BC, D0 and D30 levels and secretion (secretors = pts with detectable cytokine levels) on overall (OS), disease free (DFS) and GVHD and relapse free survival (GRFS) was also assessed. Results: Pts characteristics and cytokine levels are given in Tables 1 and 2. At D0, IL-6 (p=0.0006), FL (p<0.001) and SCF (p=0.003) levels were significantly higher in pts than controls. This remained true for SCF levels on D30 (p=0.0009), D60 (p=0.001) and D100 (p=0.01). Median GM-CSF and c-kit levels were significantly lower in pts at any time (p<0.001). Two-by-two paired cytokine comparisons showed no correlation, especially considering c-kit and its ligand SCF. ELN2017 classification and disease-risk index (DRI) were significantly associated with OS and LFS by univariate analysis (UA), only the former remaining associated with both OS (HR 8.51; 95%CI 1.18-61.54, p=0.034) and LFS (HR 8.10; 95%CI 1.20-54.82, p=0.032) in multivariate analysis (MA). Only SCF, IL-6 and c-kit levels impacted survivals. Higher pre-transplant SCF levels were associated with lower OS (p=0.02), DFS (p=0.01) and GRFS (P<0.001) by UA and remained associated with lower GRFS (HR 3.19; 95%CI 1.48-6.88, p=0.003) in MA, with a trend for lower LFS (HR 1.96; 95%CI 0.94-4.08, p=0.07). There was also an association between the absence of SCF secretion and better OS, LFS and GRFS (p=0.02, p=0.02, p=0.03) while c-kit secretion was associated with better OS (p=0.03) in UA. This remained true in MA for OS (HR 0.30; 95%CI 0.10-0.92, p=0.03) and there was a trend between no SCF secretion and GRFS (HR 0.45; 95%CI 0.18-1.14, p=0.09) by MA. Higher IL-6 levels at D0 were associated with lower OS (p=0.01) by UA and lower LFS both by UA (p=0.01) and MA (HR: 2.83; 95%CI: 1.04-7.70, p=0.04), with a trend for lower OS (HR: 2.55; 95%CI: 0.90-7.29, p=0.07) in MA. ROC curve analysis identified 7pg/mL as the best cut-off for D0 IL-6 levels which resulted, for pts under this level, in significantly better 4-year OS (80% (62-1) vs 35.7% (18-69), p=0.02) and LFS (73.3% (54-99) vs 28.6% (13-63) p=0.01; Figure). For alive patients at D30, higher c-kit and lower SCF levels were associated with better OS (p=0.003 and p=0.01) and LFS (p=0.009 and p=0.04) by UA while c-kit levels remained associated with LFS (HR: 0.37; 95%CI: 0.17-0.80, p=0.01) by MA. The absence of SCF secretion was associated with better OS (p=0.03) and a trend for better LFS (p=0.07). c-kit secretion was associated with better OS (p=0.008), LFS (p=0.01) and a trend for better GRFS (p=0.07). Only c-kit secretion remained associated with better OS (HR: 0.15; 95%CI: 0.04-0.57, p=0.005), LFS (HR: 0.19; 95%CI: 0.06-0.62, p=0.006) and GRFS (HR: 0.40.95%CI: 0.16-1.00, p=0.05) by MA. Conclusion: In this cohort, early higher IL-6 and SCF and lower c-kit levels appeared to be significantly associated with lower survivals in AML pts after Allo-HSCT. These high-risk cytokine profiles might allow to propose therapeutic intervention to decrease relapses in selected pts, either by modulating cytokine levels or by starting early maintenance treatment post-Allo-HSCT. These results have to be confirmed on larger studies. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Modulation of radiation biomarkers in a randomized phase II study of 131I-MIBG with or without radiation sensitizers for relapsed or refractory neuroblastoma: A report from the NANT Consortium.

10026 Background: 131I-metaiodobenzylguanidine (131I-MIBG) has demonstrated efficacy as a single agent for patients with neuroblastoma. Recent trials have focused on 131I-MIBG combination strategies, though little is known about the impact of combination agents on markers of radiation exposure. Methods: NANT11-01 (NCT02035137) was a multicenter, open label, randomized phase II clinical trial that evaluated 131I-MIBG therapy alone (Arm A) or in combination with vincristine/irinotecan (Arm B) or vorinostat (Arm C) for patients with resistant/relapsed neuroblastoma. We collected blood samples at baseline, 72 hours, 96 hours, and 15 days after 131I-MIBG infusion and determined levels of plasma FLT3 ligand, serum amylase, and gene expression for selected RNA transcripts (apoptosis, DNA damage response and cell cycle related). We evaluated marker association with treatment arm, clinical response using NANT response criteria, toxicity, and whole-body radiation dose. Results: The cohort included 99 patients who had at least one biomarker available for analysis (32 Arm A; 35 Arm B; 32 Arm C). We observed both positive and negative significant modulation in most biomarkers between baseline, 72 hours, and 96 hours following 131I-MIBG. Patients in Arm C had the lowest degree of modulation in FLT3 ligand. Elevated baseline levels of FLT3 ligand were significantly associated with improved Curie response but not overall response. Lower baseline BCL2 levels were associated with higher overall and Curie response. Patients with increased FLT3 ligand at 96 hours after 131I-MIBG therapy were significantly more likely to have grade 4 thrombocytopenia.Peripheral blood gene expression of the BCL2 family of apoptotic markers (BCL2/L1 and BAX) was significantly associated with grade 4 hematological toxicity. Whole-body radiation dose and PRKDC fold change at 72 hours were significantly correlated. No other individual biomarkers were correlated with whole body radiation dose at 72 or 96 hours post 131I-MIBG. Conclusions: Peripheral blood biomarkers relevant to radiation exposure demonstrate significant modulation over time after 131I-MIBG treatment. Biomarkers related to hematopoietic damage and apoptosis were associated with hematological toxicity. Patients treated with vorinostat and 31I-MIBG had differential modulation of FLT3-ligand Further use of these biomarkers may improve our ability to care for patients treated with 131I-MIBG.

A novel IgG-based FLT3xCD3 bispecific antibody for the treatment of AML and B-ALL

BackgroundIn lymphoid malignancies, the introduction of chimeric antigen receptor T (CAR-T) cells and bispecific antibodies (bsAbs) has achieved remarkable clinical success. However, such immunotherapeutic strategies are not yet established for...

Cerebrospinal Fluid Biomarkers in Multiple System Atrophy Relative to Parkinson's Disease: A Meta-Analysis.

Objective To investigate the differences of candidate cerebrospinal fluid (CSF) biomarkers associated with multiple system atrophy (MSA) and Parkinson's disease (PD). Method Here, a systematic review and meta-analysis were conducted on studies related to CSF biomarkers associated with MSA and PD obtained from PubMed, Web of Science, Embase, and Cochrane databases. Data were pooled where appropriate and used to calculate standardized mean differences (SMDs) with 95% confidence intervals (CI). Heterogeneity was assessed using the I2 statistic while Egger's test was used to test for existing publication bias. Results MSA patients had higher CSF t-tau (SMD = 0.41, 95% CI: 0.10 to 0.72) and YKL-40 (SMD = 0.63, 95% CI 0.12 to1.15) as well as DJ-1 (SMD = 1.05, 95% CI 0.67 to 1.42) levels than PD patients, while CSF p-tau (SMD = −0.17, 95% CI, -0.31 to -0.02) and Aβ-42 (SMD = −0.33, 95% CI, -0.55 to -0.12) levels in MSA patients were lower than those in PD patients. There were no differences in CSF's GFAP and Flt3 ligand levels in both MSA and PD patients. Conclusion The study revealed the differences in CSF biomarker levels between MSA and PD cohorts that can be further explored to clinically distinguish MSA from PD.

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)

FLT3 Ligand Is Dispensable for the Final Stage of Type 1 Conventional Dendritic Cell Differentiation.

Conventional dendritic cells (cDCs) are comprised of two major subsets, type 1 cDC (cDC1) and type 2 cDC (cDC2). As each cDC subset differentially influences the nature of immune responses, we sought factors that would allow the manipulation of their relative abundance. Notably, cDC1 are less abundant than cDC2 in both lymphoid and nonlymphoid organs. We demonstrate that this bias is already apparent in bone marrow precommitted precursors. However, comparison of five common inbred strains revealed a disparity in precursor-product relationship, in which mice with fewer precursors to cDC1 had more cDC1. This disparity associated with contrasting variations in CD135 (FLT3) expression on cDC subsets. Hence, we characterized the response to FLT3 ligand during cDC1 and cDC2 lineage differentiation and find that although FLT3 ligand is required throughout cDC2 differentiation, it is surprisingly dispensable during late-stage cDC1 differentiation. Overall, we find that tight regulation of FLT3 ligand levels throughout cDC differentiation dictates the cDC1 to cDC2 ratio in lymphoid organs.

The Blood Cytokine Profile of Young People with Early Ischemic Heart Disease Comorbid with Abdominal Obesity.

Objective: The aim was to study the blood cytokine/chemokine profile of 25–44-year-old people with early ischemic heart disease (IHD) comorbid with abdominal obesity (AO). Methods: A cross-sectional medical examination of subjects in Novosibirsk, Russia, was conducted after random sampling of the above age group. A total of 1457 subjects, 804 females and 653 males, were analyzed. The epidemiological diagnosis of IHD was made in accordance with 17 validated and functional criteria, employing exercise ECG for confirmation. Simultaneous quantitative analyses of 41 cytokines/chemokines in blood serum were performed by a multiplex assay using the HCYTMAG-60K-PX41 panel (MILLIPLEX MAP) on a Luminex 20 MAGPIX flow cytometer, with additional ELISA testing. Results: Flt3 ligand, GM-CSF, and MCP-1 were significantly associated with the relative risk of early IHD. In the presence of AO, GM-CSF, MCP-1 and IL-4 also significantly correlated with the relative risk of early IHD. By univariate regression analysis, the relative risk of early IHD was associated with lowered blood concentrations of Flt3 ligand, whereas the relative risk of early IHD in the presence of AO was associated with lowered blood concentrations of GM-CSF. Employing multivariable regression analysis, only lower blood levels of Flt3 ligand were associated with a relative risk of early IHD, whereas the relative risk of early IHD in the presence of AO was limited to lower levels of IL-4. Conclusion: Findings related to Flt3 ligand, GM-CSF, and IL-4 are consistent with the international literature. Results from the present study are partly confirmative and partly hypothesis generating.

FLT3 stop mutation increases FLT3 ligand level and risk of autoimmune thyroid disease.

Autoimmune thyroid disease is the most common autoimmune disease and is highly heritable1. Here, by using a genome-wide association study of 30,234cases and 725,172controls from Iceland and the UK Biobank, we find 99sequence variants at 93loci, of which 84 variants are previously unreported2-7. A low-frequency (1.36%) intronic variant in FLT3 (rs76428106-C) has the largest effect on risk of autoimmune thyroid disease (odds ratio (OR)=1.46, P=2.37×10-24). rs76428106-C is also associated with systemic lupus erythematosus (OR=1.90, P=6.46×10-4), rheumatoid factor and/or anti-CCP-positive rheumatoid arthritis (OR=1.41, P=4.31×10-4) and coeliac disease (OR=1.62, P=1.20×10-4). FLT3 encodes fms-related tyrosine kinase 3, a receptor that regulates haematopoietic progenitor and dendritic cells. RNA sequencing revealed that rs76428106-C generates a cryptic splice site, which introduces a stop codon in 30% of transcriptsthat are predicted to encode a truncated protein, which lacks its tyrosine kinase domains. Each copy of rs76428106-C doubles the plasma levels of the FTL3 ligand. Activating somatic mutations in FLT3 are associated with acute myeloid leukaemia8 with a poor prognosis and rs76428106-C also predisposes individuals to acute myeloid leukaemia (OR=1.90, P=5.40×10-3). Thus, a predicted loss-of-function germline mutation in FLT3 causes a reduction in full-length FLT3, with a compensatory increase in the levels of its ligand and an increased disease risk, similar to that of a gain-of-function mutation.

Monitoring of FLT3 Phosphorylation and FLT3 Ligand Levels in Patients with FLT3-ITD Mutated Acute Myeloid Leukemia (AML) Treated with Midostaurin within the AMLSG 16-10 Trial of the German-Austrian Study Group

Monitoring of FLT3 Phosphorylation and FLT3 Ligand Levels in Patients with FLT3-ITD Mutated Acute Myeloid Leukemia (AML) Treated with Midostaurin within the AMLSG 16-10 Trial of the German-Austrian Study Group

Abstract 2559: Generation and evaluation of an FLT3 CAR-T cell therapy for the treatment of acute myeloid leukemia

Abstract Background: FLT3 (CD135) is a receptor tyrosine kinase expressed by hematopoietic progenitor cells, and when activated by ligand binding, FLT3 signaling can induce survival, proliferation and differentiation. Acute myeloid leukemia (AML), an indication with high unmet need, derives from hematopoietic progenitor lineage cells; consequently, many AML patient samples retain FLT3 expression on circulating leukemic cells. In comparison to the wide expression seen in AML patient samples, normal tissue expression of FLT3 is restricted to the hematopoietic compartment: a subset of hematopoietic stem cells, a subset of lineage committed progenitor cells and dendritic cells. Cell surface FLT3 protein was not detectable in those solid tissues that express quantifiable FLT3 mRNA (cerebellum, pancreas). As a result of this favorable expression profile, targeting AML cells using T cells expressing a chimeric antigen receptor (CAR) directed against FLT3, is expected to provide benefit to patients. Methods: A panel of fully-human, anti-human FLT3 antibodies were generated, screened for specific FLT3 binding, converted to single chain variable fragments (scFv) and re-evaluated for binding and stability. Three anti-FLT3 scFv sequences were selected for incorporation into CAR constructs. T cells transduced with these CAR constructs were evaluated in vitro for cytotoxicity, proliferation and cytokine secretion, and in vivo in a mouse xenograft model. The lead anti-FLT3 scFv was combined with an anti-CD3 scFv (bispecific T cell engager (BiTE®) format) for evaluation in non-human primates (NHP). Results: Human T cells engineered to express anti-FLT3 CAR constructs were evaluated for cytotoxicity, proliferation and cytokine secretion in the presence of three FLT3-positive cell lines, each with a different number of surface-expressed FLT3 receptors, and one FLT3-negative cell line. While all constructs were selectively active against FLT3-positive cells, one construct was more active than the others against cells expressing very low levels of FLT3; 90% depletion of target cells with ~1600 receptors/cell was observed after 40 hours of co-culture with CAR T cells in a 1:1 ratio. This lead construct was further evaluated in a mouse xenograft model, where FLT3 CAR-T cells provided a survival advantage. The anti-FLT3 scFv used in the lead CAR construct was evaluated in NHP in the form of a BiTE®. In this 16-day, multi-dose study, the FLT3 BiTE® induced elimination of FLT3+ cells as assessed by depletion of FLT3 mRNA-expressing cells (97% reduction in FLT3 mRNA) in the circulation and increased levels of soluble FLT3 ligand in serum. Conclusions: These results demonstrate the potential of using FLT3 CAR-T cell therapy for the treatment of AML. Citation Format: Tara L. Arvedson, Alice Bakker, Herve Lebrec, Gregor Adams, Armen Madiros, Priya Koppikar, Mercedesz Balazs, Mei Gong, Yan Zheng, Rebecca Goldstein, Tony Polverino, Lawren Wu, Angela Coxon. Generation and evaluation of an FLT3 CAR-T cell therapy for the treatment of acute myeloid leukemia [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 2559.

Hemorrhage enhances cytokine, complement component 3, and caspase-3, and regulates microRNAs associated with intestinal damage after whole-body gamma-irradiation in combined injury.

Hemorrhage following whole-body γ-irradiation in a combined injury (CI) model increases mortality compared to whole-body γ-irradiation alone (RI). The decreased survival in CI is accompanied by increased bone marrow injury, decreased hematocrit, and alterations of miRNA in the kidney. In this study, our aim was to examine cytokine homeostasis, susceptibility to systemic bacterial infection, and intestinal injury. More specifically, we evaluated the interleukin-6 (IL-6)-induced stress proteins including C-reactive protein (CRP), complement 3 (C3), Flt-3 ligand, and corticosterone. CD2F1 male mice received 8.75 Gy 60Co gamma photons (0.6 Gy/min, bilateral) which was followed by a hemorrhage of 20% of the blood volume. In serum, RI caused an increase of IL-1, IL-2, IL-3, IL-5, IL-6, IL-12, IL-13, IL-15, IL-17A, IL-18, G-CSF, CM-CSF, eotaxin, IFN-γ, MCP-1, MIP, RANTES, and TNF-α, which were all increased by hemorrhage alone, except IL-9, IL-17A, and MCP-1. Nevertheless, CI further elevated RI-induced increases of these cytokines except for G-CSF, IFN- γ and RANTES in serum. In the ileum, hemorrhage in the CI model significantly enhanced RI-induced IL-1β, IL-3, IL-6, IL-10, IL-12p70, IL-13, IL-18, and TNF-α concentrations. In addition, Proteus mirabilis Gram(-) was found in only 1 of 6 surviving RI mice on Day 15, whereas Streptococcus sanguinis Gram(+) and Sphingomonas paucimobilis Gram(-) were detected in 2 of 3 surviving CI mice (with 3 CI mice diseased due to inflammation and infection before day 15) at the same time point. Hemorrhage in the CI model enhanced the RI-induced increases in C3 and decreases in CRP concentrations. However, hemorrhage alone did not alter the basal levels, but hemorrhage in the CI model displayed similar increases in Flt-3 ligand levels as RI did. Hemorrhage alone altered the basal levels of corticosterone early after injury, which then returned to the baseline, but in RI mice and CI mice the increased corticosterone concentration remained elevated throughout the 15 day study. CI increased 8 miRNAs and decreased 10 miRNAs in serum, and increased 16 miRNA and decreased 6 miRNAs in ileum tissue. Among the altered miRNAs, CI increased miR-34 in the serum and ileum which targeted an increased phosphorylation of ERK, p38, and increased NF-κB, thereby leading to increased iNOS expression and activation of caspase-3 in the ileum. Further, let-7g/miR-98 targeted the increased phosphorylation of STAT3 in the ileum, which is known to bind to the iNOS gene. These changes may correlate with cell death in the ileum of CI mice. The histopathology displayed blunted villi and villus edema in RI and CI mice. Based on the in silico analysis, miR-15, miR-99, and miR-100 were predicted to regulate IL-6 and TNF. These results suggest that CI-induced alterations of cytokines/chemokines, CRP, and C3 cause a homeostatic imbalance and may contribute to the pathophysiology of the gastrointestinal injury. Inhibitory intervention in these responses may prove therapeutic for CI and improve recovery of the ileal morphologic damage.

Ratios of T-helper 2 Cells to T-helper 1 Cells and Cytokine Levels in Patients with Hepatitis B

Background:Hepatitis B is an immune response-mediated disease. The aim of this study was to explore the differences of ratios of T-helper (Th) 2 cells to Th1 cells and cytokine levels in acute hepatitis B (AHB) patients and chronic hepatitis B virus (HBV)-infected patients in immune-tolerance and immune-active phases.Methods:Thirty chronic HBV-infected patients in the immune-tolerant phase (IT group) and 50 chronic hepatitis B patients in the immune-active (clearance) phase (IC group), 32 AHB patients (AHB group), and 13 healthy individuals (HI group) were enrolled in the study. The cell proportions in peripheral blood, cytokine levels in plasma, and serum levels of HBV DNA, hepatitis B surface antigen, and hepatitis B e antigen were detected.Results:The Th1 cell percentage and Th2/Th1 ratio in the HBV infection group (including IT, IC, and AHB groups) were significantly different from those in HI group (24.10% ± 8.66% and 1.72 ± 0.61 vs. 15.16% ± 4.34% and 2.40 ± 0.74, respectively; all P < 0.001). However, there were no differences in the Th1 cell percentages and Th2/Th1 ratios among the IT, IC, and AHB groups. In HBV infection group, the median levels of Flt3 ligand (Flt3L), interferon (IFN)-γ, and interleukin (IL)-17A were significantly lower than those in HI group (29.26 pg/ml, 33.72 pg/ml, and 12.27 pg/ml vs. 108.54 pg/ml, 66.48 pg/ml, and 35.96 pg/ml, respectively; all P < 0.05). IFN-α2, IL-10, and transforming growth factor (TGF)-β2 median levels in hepatitis group (including patients in AHB and IC groups) were significantly higher than those in IT group (40.14 pg/ml, 13.58 pg/ml, and 557.41 pg/ml vs. 16.74 pg/ml, 6.80 pg/ml, and 419.01 pg/ml, respectively; all P < 0.05), while patients in hepatitis group had significant lower Flt3L level than IT patients (30.77 vs. 59.96 pg/ml, P = 0.021). Compared with IC group, patients in AHB group had significant higher median levels of IL-10, TGF-β1, and TGF-β2 (22.77 pg/ml, 10,447.00 pg/ml, and 782.28 pg/ml vs. 8.66 pg/ml, 3755.50 pg/ml, and 482.87 pg/ml, respectively; all P < 0.05).Conclusions:Compared with chronic HBV-infected patients in immune-tolerance phase, chronic HBV-infected patients in immune-active phase and AHB patients had similar Th2/Th1 ratios, significantly higher levels of IFN-α2, IL-10, and TGF-β. AHB patients had significantly higher IL-10 and TGF-β levels than chronic HBV-infected patients in immune-active phase.

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.

Expression profiles and clinical implication of plasma chemokines in patients with Stanford type A aortic dissection

Objective: To explore the plasma chemokines expressions and related clinical implication in patients with Stanford type A aortic dissection (AD). Methods: We retrospectively analyzed the data of 65 patients with Stanford type A aortic dissection, hypertensive patients and 11 healthy subjects admitted in our department from October 2013 to December 2014, they were divided into four groups: NH-CON group (11 healthy subjects), H-AD group (29 AD patients with hypertension), NH-AD group (21 AD patients without hypertension), and H-CON group (14 hypertension patients). Four plasma samples from AD patients and 4 plasma samples from healthy subjects were collected randomly with random numbers table, and the levels of different chemokines were examined by protein array analysis. Then, plasma levels of chemokines including macrophage inflammatory protein 1β(MIP-1β), epithelial neutrophil activating peptide 78(ENA-78), interleukin 16(IL-16), interferon inducible protein 10(IP-10) and FMS-like tyrosine kinase 3(Flt-3) ligand were analyzed by luminex. Pearson analysis was used to determine the correlations between the chemokines and serum C reactive protein (CRP) levels. Results: Plasma levels of MIP-1β(34.0(29.3, 47.2) ng/L vs. 51.0(28.2, 80.7) ng/L, P<0.05) and ENA-78(110.5(59.1, 161.4) ng/L vs. 475.7(299.3, 837.3) ng/L, P<0.05) were significantly lower in H-AD group, while plasma IL-16 level was significantly higher in H-AD group(54.7(16.3, 187.8) ng/L vs. 17.5(11.9, 20.8) ng/L, P<0.05) than in H-CON group. Plasma levels of MIP-1β(48.3(26.4, 62.1) ng/L, P<0.05) were significantly lower in H-AD patients than in NH-AD patients. Plasma level of ENA-78 was significantly lower in NH-AD group than in NH-CON group (95.0(58.0, 155.0) ng/L vs. 257.7(85.2, 397.8) ng/L, P<0.05). The levels of IP-10 and Flt-3 ligand were similar among the 4 groups (all P>0.05). Pearson analysis showed that there were no correlation between MIP-1β(r(2)=0.01, P>0.05), ENA-78(r(2)=0.02, P>0.05), IL-16(r(2)=0.02, P>0.05), IP-10(r(2)=0.00, P>0.05), Flt-3 ligand(r(2)=0.02, P>0.05) and CRP levels in patients with Stanford type A aortic dissection. Conclusions: Lower plasma levels of MIP-1β and ENA-78 and higher plasma levels of IL-16 may associate with the occurrence and development of type A aortic dissection, but their concentrations are not correlated with serum CRP levels. There is no significant change on plasma levels of IP-10 and Flt-3 in the Stanford type A aortic dissection patients.

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.

Abstract 494: Evaluation of soluble FLT3 ligand as a marker of bone marrow stress and recovery

Abstract Depletion of bone marrow (BM)-resident myeloid progenitor cells is a consequence of various anti-cancer treatments, including bispecific T-cell engager (BiTE®) antibodies targeting myeloid cell antigens. Currently, aspirates are required to determine the extent of myeloid cell depletion in the BM. This procedure is painful and potentially invasive for patients. As a surrogate marker for BM myeloid cell depletion, we evaluated soluble FLT3 ligand (FLT3L) in non-human primates treated with myeloid cell-depleting BiTE® antibodies. While FLT3L is not detectable in serum during steady-state hematopoiesis, it is detectable in response to hematopoietic deficiency. The goal of this study was to evaluate the relationship of serum FLT3L with depletion and recovery of BM myeloid cells in non-human primates treated with BiTE® antibodies against CD33. Serum FLT3L levels were determined using an anti-human FLT3L ELISA kit. Validation studies demonstrated that both the capture and detection antibodies recognized cynomolgus FLT3L. Serum FLT3L concentrations were determined using a standard curve with rhesus FLT3L (99.6% identical to cynomolgus FLT3L). Serum samples were taken from cynomolgus monkeys before, during and after treatment with anti-CD33 BiTE® antibodies and compared with the number of BM-resident target cells. In the first study, cynomolgus monkeys were dosed once with different dose levels of anti-CD33 BiTE® antibody ranging from 1- 15 μg/kg. BM-resident myeloid cells were transiently reduced in some, but not all, cohorts. Soluble FLT3L was detected only when there was a reduction in BM myeloid cells. When FLT3L was detectable, the serum concentration correlated with the extent of target cell reduction and FLT3L levels decreased as the myeloid cells recovered. In the second study, cynomolgus monkeys were dosed three times with anti-CD33 BiTE® antibody. In these studies target cell reduction was greater and persisted longer compared to the single dose studies. Similarly, the magnitude and duration of increased FLT3L in the multidose studies was also greater. Within the multi-dose study, FLT3L levels continued to increase as more BM-resident myeloid cells were depleted, suggesting that it was possible to detect cumulative stress to the BM. In summary, serum FLT3L levels are correlated with the extent and duration of myeloid cell depletion in the BM suggesting that serum FLT3L levels reflect depletion and subsequent myeloid cell replenishment. All studies to date have involved treatment with myeloid antigen-specific BiTE® antibodies; future studies will evaluate FLT3L levels following treatment with anti-lymphoid or solid tumor antigen-specific BiTE® antibodies to determine if FLT3L increases are associated with myeloid cell depletion or indicative of general BM stress or inflammation. The potential benefit of this marker is that it could allow for repeat non-invasive BM monitoring in patients on myelosuppressive therapies. Citation Format: Christine Sastri, Mercedesz Balazs, Priya Koppikar, James R. Lipford, Angela Coxon, Tara L. Arvedson. Evaluation of soluble FLT3 ligand as a marker of bone marrow stress and recovery. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 494.

Peripheral FLT-3 ligand levels as a pathobiological parameter duringthe clinical course of acute myeloid leukemia.

FLT-3 ligand is a growth factor affecting the hematopoietic lineage. The aim of this study was to evaluate the variability of peripheral FLT-3 ligand during the clinical course of acute myeloid leukemia (AML) patients. Twenty-four patients were enrolled in this study in order to assess alterations in the circulating levels of FLT-3 ligand during the clinical course of AML. We studied the association in the diagnostic period between the FLT-3 ligand and peripheral blood cells together with serum electrolytes. FLT-3 ligand levels (pg/mL) during the aplastic period due to remission induction and consolidation were higher than the levels at initial diagnosis. On the other hand, the diagnostic and remission induction values of leukocytes and FLT-3 ligand showed an inverse association. These results indicate to us that higher white cell counts are associated with lower FLT-3 ligand levels. We also found a reversed association between FLT-3 ligand and serum lactate dehydrogenase level. However, there was no association between FLT-3 ligand and other serum electrolyte levels. We also found higher FLT-3 ligand levels in male patients. Our study demonstrates the inverse proliferative action of FLT-3 ligand on the early myeloid lineage. In addition, this study showed us that FLT-3 receptor inhibition during chemotherapy-induced aplasia causes a compensative ligand overexpression.