Survival Invivo Research Articles

Mammalian SWI/SNF complex activity regulates POU2F3 and constitutes a targetable dependency in small cell lung cancer

Small cell lung cancers (SCLCs) are composed of heterogeneous subtypes marked by lineage-specific transcription factors, including ASCL1, NEUROD1, and POU2F3. POU2F3-positive SCLCs, ∼12% of all cases, are uniquely dependent on POU2F3 itself; as such, approaches to attenuate POU2F3 expression may represent new therapeutic opportunities. Here using genome-scale screens for regulators of POU2F3 expression and SCLC proliferation, we define mSWI/SNF complexes as top dependencies specific to POU2F3-positive SCLC. Notably, chemical disruption of mSWI/SNF ATPase activity attenuates proliferation of all POU2F3-positive SCLCs, while disruption of non-canonical BAF (ncBAF) via BRD9 degradation is effective in pure non-neuroendocrine POU2F3-SCLCs. mSWI/SNF targets to and maintains accessibility over gene loci central to POU2F3-mediated gene regulatory networks. Finally, clinical-grade pharmacologic disruption of SMARCA4/2 ATPases and BRD9 decreases POU2F3-SCLC tumor growth and increases survival invivo. These results demonstrate mSWI/SNF-mediated governance of the POU2F3 oncogenic program and suggest mSWI/SNF inhibition as a therapeutic strategy for POU2F3-positive SCLCs.

TNF-NF-κB-p53 axis restricts in vivo survival of hPSC-derived dopamine neurons

Ongoing, early-stage clinical trials illustrate the translational potential of human pluripotent stem cell (hPSC)-based cell therapies in Parkinson's disease (PD). However, an unresolved challenge is the extensive cell death following transplantation. Here, we performed a pooled CRISPR-Cas9 screen to enhance postmitotic dopamine neuron survival invivo. We identified p53-mediated apoptotic cell death as a major contributor to dopamine neuron loss and uncovered a causal link of tumor necrosis factor alpha (TNF-α)-nuclear factor κB (NF-κB) signaling in limiting cell survival. As a translationally relevant strategy to purify postmitotic dopamine neurons, we identified cell surface markers that enable purification without the need for genetic reporters. Combining cell sorting and treatment with adalimumab, a clinically approved TNF-α inhibitor, enabled efficient engraftment of postmitotic dopamine neurons with extensive reinnervation and functional recovery in a preclinical PD mouse model. Thus, transient TNF-α inhibition presents a clinically relevant strategy to enhance survival and enable engraftment of postmitotic hPSC-derived dopamine neurons in PD.

RUNX1::ETO and CBFβ::MYH11 converge on aberrant activation of BCAT1 to confer a therapeutic vulnerability in core-binding factor-acute myeloid leukaemia.

Effectively targeting transcription factors in therapeutic interventions remains challenging, especially in core-binding factor-acute myeloid leukaemia (CBF-AML) characterized by RUNX1::ETO and CBFβ::MYH11 fusions. However, recent studies have drawn attention towards aberrant amino acid metabolisms as actionable therapeutic targets. Here, by integrating the expression profile and genetic makeup in AML cohort, we found higher BCAT1 expression in CBF-AML patients compared with other subtypes. Metabolic profiling revealed that high BCAT1 expression led to reprogrammed branch amino acid metabolism in CBF-AML and was associated with sphingolipid pathway relating to the fitness of leukaemia cells, supported by transcriptomic profiling. Mechanistically, we demonstrated in cell lines and primary patient samples that BCAT1 was directly activated by RUNX1::ETO and CBFβ::MYH11 fusion proteins similarly in a RUNX1-dependent manner through rewiring chromatin conformation at the BCAT1 gene locus. Furthermore, BCAT1 inhibition resulted in blunted cell cycle, enhanced apoptosis and myeloid differentiation of CBF-AML cells invitro, and alleviated leukaemia burden and prolonged survival invivo. Importantly, pharmacological inhibition of BCAT1 using the specific inhibitor Gabapentin demonstrated therapeutic effects, as evidenced by delayed leukaemia progression and improved survival invivo. In conclusion, our study uncovers BCAT1 as a genetic vulnerability and a promising targeted therapeutic opportunity for CBF-AML.

Prolyl hydroxylase 2 inhibits glycolytic activity in colorectal cancer via the NF‑κB signaling pathway.

A variety of malignancies preferentially meet energy demands through the glycolytic pathway. Hypoxia‑induced cancer cell adaptations are essential for tumor development. However, in cancerous glycolysis, the functional importance and underlying molecular mechanism of prolyl hydroxylase domain protein 2 (PHD2) have not been fully elucidated. Gain‑ and loss‑of‑function assays were conducted to evaluate PHD2 functions in colon cancer cells. Glucose uptake, lactate production and intracellular adenosine‑5'‑triphosphate/adenosine diphosphate ratio were measured to determine glycolytic activities. Protein and gene expression levels were measured by western blot analysis and reverse transcription‑quantitative PCR, respectively. The human colon cancer xenograft model was used to confirm the role of PHD2 in tumor progression invivo. Functionally, the data demonstrated that PHD2 knockdown leads to increased glycolysis, while PHD2 overexpression resulted in suppressed glycolysis in colorectal cancer cells. In addition, the glycolytic activity was enhanced without PHD2 and normalized after PHD2 reconstitution. PHD2 was shown to inhibit colorectal tumor growth, suppress cancer cell proliferation and improve tumor‑bearing mice survival invivo. Mechanically, it was found that PHD2 inhibits the expression of critical glycolytic enzymes (glucose transporter 1, hexokinase 2 and phosphoinositide‑dependent protein kinase 1). In addition, PHD2 inhibited Ikkβ‑mediated NF‑κB activation in a hypoxia‑inducible factor‑1α‑independent manner. In conclusion, the data demonstrated that PHD2/Ikkβ/NF‑κB signaling has critical roles in regulating glycolysis and suggests that PHD2 potentially suppresses colorectal cancer.

Smoking induces WEE1 expression to promote docetaxel resistance in esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) patients have poor clinical outcomes, with an overall 5-year survival rate of 20%. Smoking is a significant risk factor for EAC. The role of WEE1, a nuclear kinase that negatively regulates the cell cycle in normal conditions, in EAC tumorigenesis and drug resistance is not fully understood. Immunohistochemistry staining shows significant WEE1 overexpression in human EAC tissues. Nicotine, nicotine-derived nitrosamine ketone, or 2% cigarette smoke extract treatment induces WEE1 protein expression in EAC, detected by western blot and immunofluorescence staining. qRT-PCR and reporter assay indicates that smoking induces WEE1 expression through miR-195-5p downregulation in EAC. ATP-Glo cell viability and clonogenic assay confirmed that WEE1 inhibition sensitizes EAC cells to docetaxel treatment invitro. A TE-10 smoking machine with EAC patient-derived xenograft mouse model demonstrated that smoking induces WEE1 protein expression and resistance to docetaxel invivo. MK-1775 and docetaxel combined treatment improves EAC patient-derived xenograft mouse survival invivo. Our findings demonstrate, for the first time, that smoking-induced WEE1 overexpression through miRNA dysregulation in EAC plays an essential role in EAC drug resistance. WEE1 inhibition is a promising therapeutic method to overcome drug resistance and target treatment refractory cancer cells.

A target discovery pipeline identified ILT3 as a target for immunotherapy of multiple myeloma

Multiple myeloma (MM) is an incurable malignancy of plasma cells. To identify targets for MM immunotherapy, we develop an integrated pipeline based on mass spectrometry analysis of seven MM cell lines and RNA sequencing (RNA-seq) from 900+ patients. Starting from 4,000+ candidates, we identify the most highly expressed cell surface proteins. We annotate candidate protein expression in many healthy tissues and validate the expression of promising targets in 30+ patient samples with relapsed/refractory MM, as well as in primary healthy hematopoietic stem cells and Tcells by flow cytometry. Six candidates (ILT3, SEMA4A, CCR1, LRRC8D, FCRL3, IL12RB1) and B cell maturation antigen (BCMA) present the most favorable profile in malignant and healthy cells. We develop a bispecific Tcell engager targeting ILT3 that shows potent killing effects invitro and decreased tumor burden and prolonged mice survival invivo, suggesting therapeutic relevance. Our study uncovers MM-associated antigens that hold great promise for immune-based therapies of MM.

Novel Fas-TNFR chimeras that prevent Fas ligand-mediated kill and signal synergistically to enhance CAR T cell efficacy

The hostile tumor microenvironment limits the efficacy of adoptive cell therapies. Activation of the Fas death receptor initiates apoptosis and disrupting these receptors could be key to increasing CAR Tcell efficacy. We screened a library of Fas-TNFR proteins identifying several novel chimeras that not only prevented Fas ligand-mediated kill, but also enhanced CAR Tcell efficacy by signaling synergistically with the CAR. Upon binding Fas ligand, Fas-CD40 activated the NF-κB pathway, inducing greatest proliferation and IFN-γ release out of all Fas-TNFRs tested. Fas-CD40 induced profound transcriptional modifications, particularly genes relating to the cell cycle, metabolism, and chemokine signaling. Co-expression of Fas-CD40 with either 4-1BB- or CD28-containing CARs increased invitro efficacy by augmenting CAR Tcell proliferation and cancer target cytotoxicity, and enhanced tumor killing and overall mouse survival invivo. Functional activity of the Fas-TNFRs were dependent on the co-stimulatory domain within the CAR, highlighting crosstalk between signaling pathways. Furthermore, we show that a major source for Fas-TNFR activation derives from CAR Tcells themselves via activation-induced Fas ligand upregulation, highlighting a universal role of Fas-TNFRs in augmenting CAR Tcell responses. We have identified Fas-CD40 as the optimal chimera for overcoming Fas ligand-mediated kill and enhancing CAR Tcell efficacy.

RNA-regulatory exosome complex suppresses an apoptotic program to confer erythroid progenitor cell survival invivo.

The RNA-regulatory exosome complex (EC) posttranscriptionally and cotranscriptionally processes and degrades RNAs in a context-dependent manner. Although the EC functions in diverse cell types, its contributions to stem and progenitor cell development are not well understood. Previously, we demonstrated that the transcriptional regulator of erythrocyte development, GATA1, represses EC subunit genes, and the EC maintains erythroid progenitors invitro. To determine if this mechanism operates invivo, we used the hematopoietic-specific Vav1-Cre and "conditional by inversion" mouse system to ablate Exosc3, encoding an EC structural subunit. Although Exosc3C/C Cre+ embryos developed normally until embryonic day 14.5, Exosc3 ablation was embryonic lethal and severely reduced erythromyeloid progenitor activity. RNA sequencing analysis of Exosc3-ablated burst-forming unit-erythroid revealed elevated transcripts encoding multiple proapoptotic factors, and the mutant erythroid progenitors exhibited increased apoptosis. We propose that the EC controls an ensemble of apoptosis-regulatory RNAs, thereby promoting erythroid progenitor survival and developmental erythropoiesis invivo.

Development of a 5-FU modified miR-129 mimic as a therapeutic for non-small cell lung cancer

Lung cancer is the leading cause of cancer-related deaths in the United States with non-small cell lung cancer (NSCLC) accounting for most cases. Despite advances in cancer therapeutics, the 5-year survival rate has remained poor due to several contributing factors, including its resistance to therapeutics. Therefore, there is a pressing need to develop therapeutics that can overcome resistance. Non-coding RNAs, including microRNAs (miRNAs), have been found to contribute to cancer resistance and therapeutics by modulating the expression of several targets involving multiple key mechanisms. In this study, we investigated the therapeutic potential of miR-129 modified with 5-fluorouracil (5-FU) in NSCLC. Our results show that 5-FU modified miR-129 (5-FU-miR-129) inhibits proliferation, induces apoptosis, and retains function as an miRNA in NSCLC cell lines A549 and Calu-1. Notably, we observed that 5-FU-miR-129 was able to overcome resistance to tyrosine kinase inhibitors and chemotherapy in cell lines resistant to erlotinib or 5-FU. Furthermore, we observed that the inhibitory effect of 5-FU-miR-129 can also be achieved inNSCLC cells under vehicle-free conditions. Finally, 5-FU-miR-129 inhibited NSCLC tumor growth and extended survival invivo without toxic side effects. Altogether, our results demonstrate the potential of 5-FU-miR-129 as a highly potent cancer therapeutic in NSCLC.

Exosome-mediated inhibition of microRNA-449a promotes the amplification of mouse retinal progenitor cells and enhances their transplantation in retinal degeneration mouse models

Inherited and age-related retinal degenerations are the commonest causes of blindness without effective treatments. Retinal progenitor cells (RPCs), which have the multipotency to differentiate into various retinal cell types, are regarded as a promising source of cell transplantation therapy for retinal degenerative diseases. However, the self-limited expansion of RPCs causes difficulty in cell source supply and restrict its clinical treatment. In this work, we found that inhibition of microRNA-449a (miR-449a) in RPCs can promote proliferation and inhibit apoptosis of RPCs, partially through upregulating Notch signaling. Further optimization of transduction miR-449a inhibitor into RPCs by endothelial cell-derived exosomes can promote the survival of RPCs transplanted invivo and reduce cell apoptosis in retinal degeneration mouse models. In summary, these studies have shown that exosome-miR-449a inhibitor can effectively promote the expansion of RPCs invitro and enhance transplanted RPCs survival invivo, which might provide a novel intervention strategy for retinal degenerations in the future.

Novel Chemical Series of Anti-ST2 Small Molecules Suppress Allogeneic T Cells Proliferation While Increasing Treg Cells and Improve Gvhd and Survival In Vivo

Elevation of soluble Stimulation-2 (sST2) is considered a prognostic biomarker in several disease progression, such as cardiac allo-rejection, graft-versus-host disease (GVHD), and is associated with the response to tissue damage that secrets Interleukin-33 (IL-33), an alarmin. sST2 is an alternatively spliced isoform of the Interleukin 1 Receptor-Like 1 (IL1RL1) gene that also encodes the major membrane-bound ST2 (ST2) isoform expressed on tolerogenic immune cells including Foxp3+ regulatory T cells (Tregs), type 2 innate lymphoid cells (ILC2), type 2 helper T cells (Th2), monocytes, M2 macrophages, mast cells, eosinophils and neutrophils. IL-33 is the only known ligand that binds to both sST2 and ST2. Binding of IL-33 to ST2 activates intracellular signaling in ST2 expressing cells whereas sST2 functions as a decoy receptor to sequester the secreted free IL-33. After allogeneic hematopoietic cell transplantation (HCT), elevated sST2 levels are associated with patients with GVHD resistant to steroid therapy and with subsequent non-relapse related death. We hypothesized that therapeutic intervention to release IL-33 from sST2 may modulate the T cells responses for treating GVHD. As proof-of-concept, we have reported studies using either ST2 antibodies (Zhang et. al., Sci. Trans. Med. 2015) or small-molecule ST2 inhibitors (iST2-1 in Ramadan et. al., JCI Insight, 2018) in the murine GVHD models. Herein, we report a novel series of small-molecule ST2 inhibitors from our follow-up development of iST2-1. We show a representative compound, XY-52, effectively reduced sST2 levels, alleviated GVHD and improved survival in a murine GVHD model. Based on our previously discovered iST2-1, we recently developed 1-(furan-2ylmethyl)pyrrolidine-based ST2 Inhibitors and constructed the structure-activity relationship (SAR) of compounds against ST2/IL-33 binding (Yuan et. al., Bioorg. Med. Chem., 2022). That study led to identify 14e (Fig. 1A) that has an IC50 value of 7.77 mM against ST2/IL33 binding determined by the AlphaLISA assay. Despite the improvement of the IC50 value as compared to iST2-1, 14e has deficiency in solubility and metabolic stability (including a similar in vivo half-life as iST2-1) that required further optimization. To improve 14e, we first focused on replacing the furan group (C-ring) of 14e with the goal of eliminating the potential metabolic issue of the furan group. We found replacement of furan by either a pyrrole (ST2-J-100) or an alkylated pyrrole group (ST2-J-106, 107) retained the activity of the inhibitors. We then investigated the replacement of the chemical groups on A and B rings of 14e aiming to improve the solubility of the inhibitors while maintaining their activities. These modifications led to identify a new series of ST2 inhibitors represented by XY-52. In the mixed lymphocyte reaction (MLR) assay, we found XY-52 and analogs (XY-125, XY-146, XY-148, XY-150) inhibited CD4+, CD8+ T cell proliferation while increased Tregs (Fig. 1B). XY-52 has improved in vitro (t1/2= >60m in mouse, 41m in human liver microsome) and in vivo metabolic stability. In vivo PK study showed that XY-52 has higher tissue distribution including spleen, lung, skin, small intestine and liver than iST2-1 or Ruxolitinib (Fig. 1C). XY-52 was then selected to compare with 3c (previously reported) in a clinically relevant minor-mismatched GVHD mouse model (C57BL/6→C3H.SW). Using a 21-day prophylactic regimen of 40mg/kg/day (BID), we found that 3c reduced GVHD score (P=0.02) and extended survival (HR 3.90, P=0.02) in mice. Mice receiving XY-52 treatment had a more profound reduction in GVHD score (P<0.0001) and improvement in survival (HR, 31.22, P<0.0001) (Fig. 1D). Both 3c and XY-52 yielded lower plasma concentrations of sST2 and IFNg compared with the DMSO control (Fig. 1E) at Day 7 and 21 post-HCT. Ex vivo analysis of T cells in the gastrointestinal tract (GI) at day 21 post-HCT showed that XY-52 was more effective than 3c at reducing CD4+ IFNg+, CD8+ IFNγ+, CD4+ IL-17A+ T cells and increasing CD4+ Foxp3+ Tregs frequencies. In summary, XY-52 represents a promising ST2 inhibitor that reduces the plasma sST2 levels, CD4+, CD8+ effector T cells and increases CD4+ Foxp3+ Tregs frequencies in in vitro and in vivo GVHD models. Further improvement in the potency and the PK profile of XY-52 will allow us to develop effective ST2 inhibitors for use as a prophylactic or therapeutic regimen for GVHD therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Neuropeptide Alpha-Melanocyte–Stimulating Hormone Is Critical for Corneal Endothelial Cell Protection and Graft Survival after Transplantation

Corneal transplantation is the most common form of tissue transplantation. The success of corneal transplantation mainly relies on the integrity of corneal endothelial cells (CEnCs), which maintain tissue transparency by pumping out excess water from the cornea. After transplantation, the rate of CEnC loss far exceeds that seen with normal aging, which can threaten sight. The underlying mechanisms are poorly understood. Alpha-melanocyte-stimulating hormone (α-MSH) is a neuropeptide that is constitutively found in the aqueous humor with both cytoprotective and immunomodulatory effects. The curent study found high expression of melanocortin 1 receptor (MC1R), the receptor for α-MSH, on CEnCs. The effect of α-MSH/MC1R signaling on endothelial function and allograft survival invitro and invivo was investigated using MC1R signaling-deficient mice (Mc1re/e mice with a nonfunctional MC1R). Herein, the results indicate that in addition to its well-known immunomodulatory effect, α-MSH has cytoprotective effects on CEnCs after corneal transplantation, and the loss of MC1R signaling significantly decreases long-term graft survival invivo. In conclusion, α-MSH/MC1R signaling is critical for CEnC function and graft survival after corneal transplantation.

IMGN779, a Next Generation CD33-Targeting ADC, Combines Effectively with Cytarabine in Acute Myeloid Leukemia (AML) Preclinical Models, Resulting in Increased DNA Damage Response, Cell Cycle Arrest and Apoptosis In Vitro and Prolonged Survival In Vivo

Introduction: IMGN779, a next generation CD33-targeting ADC, is comprised of a novel DNA alkylating IGN payload, an s-SPDB cleavable linker and a humanized anti-CD33 antibody. IMGN779 is currently in Phase I dose escalation in patients with relapsed/refractory AML (NCT02674763). With improved patient outcomes in mind, we set out to evaluate the mechanism, antileukemia efficacy and tolerability of the combination of IMGN779 and cytarabine using in vitro and in vivo human AML preclinical models.Methods: DNA damage, survival and apoptotic responses to IMGN779 and cytarabine were assessed using flow cytometry and immunoblotting techniques. In vitro combinations of the free IGN payload and either an MDM2 antagonist or CHK1/2 inhibitors were assessed for impact on cell viability at 72 hours across a panel of 12 AML cell lines. IMGN779 and cytarabine were evaluated in vivo for antitumor activity, using disseminated (Molm-13 and MV4-11) and subcutaneous (SC; EOL-1) AML xenograft models. All mice were monitored for body weight loss, clinical signs, and SC tumor volume (EOL-1). Assessment was terminated for weight loss >20%, clinical signs, or, in the EOL-1 model, when SC tumor volume reached approximately 1000 mm3.Results: Exposure to cytarabine in vitro led to a dose- and time-dependent increase in CD33 transcription and cell surface expression (up to 2-fold increase at 150nM at 72 hours) in multiple human AML cell lines, revealing a novel mechanism by which cytarabine may potentiate the CD33-dependent uptake of IMGN779 by AML cells. Importantly, the in vitro combination of IMGN779 and cytarabine led to dose-dependent, additive antileukemia activity (Figure A), and enhanced levels of cell cycle arrest, DNA damage response (p21, CHK2) and apoptosis (Casp3/PARP1 cleavage). Moreover, the mechanistic importance of p53 and CHK2 in IMGN779-mediated antileukemia activity was demonstrated further using the IGN free payload in in vitro combination assays with a panel of 12 human AML cell lines. The results of these experiments suggest strong synergy between IGN free payload and an MDM2 antagonist and between IGN free payload and CHK1/2 inhibitors, pointing to additional combination regimens for IMGN779.In mice, the combination of single dose (0.253 mg/kg) or repeat dosing of IMGN779 (0.0534 or 0.0107 mg/kg, weekly x3) and high-dose cytarabine (75 mg/kg, at near MTD, daily x5) was highly active in all three AML xenograft models, and was well tolerated, with no body weight loss or other toxicities noted. The IMGN779 doses in these highly active combinations were far below the MTD (48 mg/kg). In MV4-11 and Molm-13 (both FLT3-ITD) disseminated xenografts, the combination resulted in a highly active 24-26 day tumor growth delay and 42-110% Increased Life Span (ILS), compared to minimally active IMGN779 (15-33% ILS) and inactive cytarabine (0-0% ILS) single agents. In the EOL-1 (chemo-resistant) SC model, 0.253 mg/kg single dose IMGN779 plus cytarabine was also highly active, resulting in 4/6 long-term (>90 days) complete remissions (CRs), compared to 2/6 CRs for IMGN779 and no CRs for cytarabine single agents (Figure B). Tumor growth delay for the EOL-1 tumors that persisted was 17 days for the combination, compared to 8 and 0.5 days for IMGN779 and cytarabine, respectively, supporting a highly beneficial combination effect on survival.Conclusions: IMGN779 and cytarabine are a highly effective and well tolerated combination in preclinical models of AML. Mechanistically, the IMGN779 plus cytarabine combination increased DNA damage response, cell cycle arrest, and apoptosis in vitro, which lead to increased survival in vivo . Interestingly, cytarabine increased cell surface CD33 levels on AML cells, indicating a novel mechanism by which cytarabine may potentiate IMGN779 uptake and possibly efficacy. In addition to the favorable combination with cytarabine, our in vitro combination studies also reveal the potential of combining IMGN779 with DNA damage response inhibitors. These results support rapidly advancing the combination of IMGN779 and high dose cytarabine in clinical trials. [Display omitted] DisclosuresAdams:ImmunoGen: Employment. Kelly:ImmunoGen: Employment. McCarthy:ImmunoGen: Employment. Wilhelm:ImmunoGen: Employment. Watkins:ImmunoGen: Employment. Lanieri:ImmunoGen: Employment. Sloss:ImmunoGen: Employment. Romanelli:ImmunoGen: Employment.

Combining IMGN632, a Novel CD123-Targeting Antibody Drug Conjugate with Azacitidine and Venetoclax Facilitates Apoptosis in Vitro and Prolongs Survival In Vivo in AML Models

Combining IMGN632, a Novel CD123-Targeting Antibody Drug Conjugate with Azacitidine and Venetoclax Facilitates Apoptosis in Vitro and Prolongs Survival In Vivo in AML Models

Loss of BCAA Catabolism during Carcinogenesis Enhances mTORC1 Activity and Promotes Tumor Development and Progression

Tumors display profound changes in cellular metabolism, yet how these changes aid the development and growth of tumors is not fully understood. Here we use a multi-omic approach to examine liver carcinogenesis and regeneration, and find that progressive loss of branched-chain amino acid (BCAA) catabolism promotes tumor development and growth. In human hepatocellular carcinomas and animal models of liver cancer, suppression of BCAA catabolic enzyme expression led to BCAA accumulation in tumors, though this was not observed in regenerating liver tissues. The degree of enzyme suppression strongly correlated with tumor aggressiveness, and was an independent predictor of clinical outcome. Moreover, modulating BCAA accumulation regulated cancer cell proliferation invitro, and tumor burden and overall survival invivo. Dietary BCAA intake in humans also correlated with cancer mortality risk. In summary, loss of BCAA catabolism in tumors confers functional advantages, which could be exploited by therapeutic interventions in certain cancers.

Ex vivo expanded natural regulatory T cells from patients with end-stage renal disease or kidney transplantation are useful for autologous cell therapy

Novel concepts employing autologous, exvivo expanded natural regulatory T cells (nTreg) for adoptive transfer has potential to prevent organ rejection after kidney transplantation. However, the impact of dialysis and maintenance immunosuppression on the nTreg phenotype and peripheral survival is not well understood, but essential when assessing patient eligibility. The current study investigates regulatory T-cells in dialysis and kidney transplanted patients and the feasibility of generating a clinically useful nTreg product from these patients. Heparinized blood from 200 individuals including healthy controls, dialysis patients with end stage renal disease and patients 1, 5, 10, 15, 20 years after kidney transplantation were analyzed. Differentiation and maturation of nTregs were studied by flow cytometry in order to compare dialysis patients and kidney transplanted patients under maintenance immunosuppression to healthy controls. CD127 expressing CD4+CD25highFoxP3+ nTregs were detectable at increased frequencies in dialysis patients with no negative impact on the nTreg end product quality and therapeutic usefulness of the exvivo expanded nTregs. Further, despite that immunosuppression mildly altered nTreg maturation, neither dialysis nor pharmacological immunosuppression or previous acute rejection episodes impeded nTreg survival invivo. Accordingly, the generation of autologous, highly pure nTreg products is feasible and qualifies patients awaiting or having received allogenic kidney transplantation for adoptive nTreg therapy. Thus, our novel treatment approach may enable us to reduce the incidence of organ rejection and reduce the need of long-term immunosuppression.

C-FLIP Expression in Foxp3-Expressing Cells Is Essential for Survival of Regulatory T Cells and Prevention of Autoimmunity

Regulatory T (Treg) cells are critical for the shutdown of immune responses and have emerged as valuable targets of immunotherapies. Treg cells can rapidly proliferate; however, the homeostatic processes that limit excessive Treg cell numbers are poorly understood. Here, we show that, compared to conventional Tcells, Treg cells have a high apoptosis rate exvivo correlating with low c-FLIP expression. Treg-specific deletion of c-FLIP in mice resulted in fatal autoimmune disease of a scurfy-like phenotype characterized by absent peripheral Treg cells, activation of effector cells, multi-organ immune cell infiltration, and premature death. Surprisingly, blocking CD95L did not rescue Treg survival invivo, suggesting additional survival functions of c-FLIP in Treg cells in addition to its classical role in the inhibition of death receptor signaling. Thus, our data reveal a central role for c-FLIP in Treg cell homeostasis and prevention of autoimmunity.

Small Molecule ST2 Inhibitors Cause Reduction of Soluble ST2 and Improve Gvhd and Survival In Vivo

Activation of the membrane-bound Suppression of Tumorigenecity 2 (mST2) by Interleukin-33 (IL-33) in T cells leads to type-2 (Th2) and Foxp3+ regulatory (Tregs) immune responses. The mST2/IL-33 axis is not engaged when a ST2 splice isoform containing only the ST2 ectodomain and acting as a decoy receptor, called soluble ST2 (sST2), sequesters IL-33. Clinically, elevated plasma sST2 has been reported and used as a prognostic biomarker in cardiac allo-rejection, inflammatory bowel disease, and graft-versus-host disease (GVHD). We hypothesized that releasing IL-33 from circulating sST2 may augment the mST2/IL-33 axis activation to modulate the Th1 and Th2/Tregs responses for treating immune related diseases. This is supported by our study of a ST2 antibody in the GVHD models (Zhang et. al., Sci. Trans. Med. 2015). Advantages of small-molecule therapies over biologics include easier administration especially by oral, superior tissue penetration, modifiable pharmacokinetic properties including half-life, and lower manufacturing cost. Here, we present the proof-of-concept of this approach using three small molecule ST2 inhibitors we discovered recently. Our data show two inhibitors cause reduction of sST2, alleviate GVHD and improve survival in two in vivo GVHD models.Our high throughput screening (HTS) using the AlphaLISA assay and computational analysis led to discover three classes of small molecules inhibiting ST2 binding to IL-33 which were confirmed by the functional cell-based HEK-Blue assay. Seven compounds showing low toxicity at 66 uM to peripheral blood mononuclear cells (PBMC) were selected for the dose escalation toxicity study in mice. Six of them showed no toxicity up to 20 mg/kg in 13 days while five of them can be tolerated at 40 mg/kg. The HTS workflow is summarized in Fig. 1.Three compounds (named iST2-1-3) were evaluated in the in vivo GVHD disease models. The first model is the transplantation of human PBMC to the NOD/SCID/IL2rgnull (NSG) mice one day after the mice received 300 cGy total body irradiation (TBI). Compounds were injected via the intraperitoneal route to the mice the day before transplantation and continued daily at their respective IC50 dosages for 21 days. At Day 14, both iST2-1 and iST2-2 caused reduction of IFNg+ CD4+ T cells and increase of Foxp3+CD4+ Tregs population in the human CD45+CD4+ cells extracted from the gastrointestinal (GI), the main GVHD target organ, compared with the DMSO control (Fig. 2). More profound effect exerted by iST2-1 was observed at Day 21. Plasma concentrations of human IFNg and sST2, indicators of Th1 response, showed the highest reduction in the iST2-1 treatment group. While the hsST2 plasma concentration is maintained at < 30 pg/ml throughout 28 days in the iST2-1 treatment group, escalation of hsST2 up to 180 pg/ml was found in the DMSO control and iST2-3 treated group. Plasma hIFNg was at least 50% lower in the iST2-1 treated group at day 14 and 21. The GVHD scores and survival of NSG mouse models paralleled the changes of GI T cell populations and systemic cytokines data; iST2-1 treatment showed decreased GVHD score to 3 from 6 in the DMSO control and improvement of survival rate to 45 % on day 35 whereas all mice in the DMSO control group were dead.The second model is the minor mismatched model of allogeneic hematopoietic cell transplantation (HCT) from B6 to C3H.SW mice. We observed similar trends of IFNg+ reduction and Foxp3+ increase in CD4+ Tcells from the GI (Fig. 3). Plasma sST2 and IFNg concentrations were greatly reduced on day 14 in the iST2-1 treated group compared with DMSO control (50 versus 10 ng/ml for sST2 and 350 versus 100 pg/ml for IFNg).Finally, we have collected the Small Angle X-ray Scattering data to construct structural models between iST2-1 and sST2 to guide the inhibitor optimization. The CRISP-Cas9 technology was also used to obtain sST2 deficient B6 mice. Allo-HCT using these donor sST2 deficient T cells will delineate the specific mode of action by our ST2 inhibitors on mST2 and sST2. Our findings reveal iST2-1 is an attractive small molecule ST2 inhibitor that can be used to study the mST2/IL-33 axis in disease models and further developed as therapeutics to treat GVHD. [Display omitted] [Display omitted] [Display omitted] DisclosuresPaczesny:Viracor-IBT Laboratories: Patents & Royalties.

NMDA Receptors Enhance Spontaneous Activity and Promote Neuronal Survival in the Developing Cochlea

Spontaneous bursts of activity in developing sensory pathways promote maturation of neurons, refinement of neuronal connections, and assembly of appropriate functional networks. In the developing auditory system, inner hair cells (IHCs) spontaneously fire Ca(2+) spikes, each of which is transformed into a mini-burst of action potentials in spiral ganglion neurons (SGNs). Here we show that NMDARs are expressed in SGN dendritic terminals and play a critical role during transmission of activity from IHCs to SGNs before hearing onset. NMDAR activation enhances glutamate-mediated Ca(2+) influx at dendritic terminals, promotes repetitive firing of individual SGNs in response to each synaptic event, and enhances coincident activity of neighboring SGNs that will eventually encode similar frequencies of sound. Loss of NMDAR signaling from SGNs reduced their survival both invivo and invitro, revealing that spontaneous activity in the prehearing cochlea promotes maturation of auditory circuitry through periodic activation of NMDARs in SGNs.

C-Kit Receptor Signaling Regulates Islet Vasculature, β-Cell Survival, and Function In Vivo.

The receptor tyrosine kinase c-Kit plays an integral role in maintaining β-cell mass and function. Although c-Kit receptor signaling promotes angiogenesis in multiple cell types, its role in islet vasculature is unknown. This study examines the effects of c-Kit-mediated vascular endothelial growth factor isoform A (VEGF-A) and islet vascularization on β-cell function and survival using in vitro cell culture and in vivo mouse models. In cultured INS-1 cells and primary islets, c-Kit regulates VEGF-A expression via the Akt/mammalian target of rapamycin (mTOR) signaling pathway. Juvenile mice with mutated c-Kit (c-Kit(Wv/+)) showed impaired islet vasculature and β-cell dysfunction, while restoring c-Kit expression in β-cells of c-Kit(Wv/+) mice rescued islet vascular defects through modulation of the Akt/mTOR/VEGF-A pathway, indicating that c-Kit signaling in β-cells is a required regulator for maintaining normal islet vasculature. Furthermore, β-cell-specific c-Kit overexpression (c-KitβTg) in aged mice showed significantly increased islet vasculature and β-cell function, but, when exposed to a long-term high-fat diet, c-Kit signaling in c-KitβTg mice induced substantial vascular remodeling, which resulted in increased islet inflammatory responses and β-cell apoptosis. These results suggest that c-Kit-mediated VEGF-A action in β-cells plays a pivotal role in maintaining islet vascularization and function.