Extracellular Nicotinamide Phosphoribosyltransferase Is a Therapeutic Target in Experimental Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of prematurity. Postulated mechanisms leading to inflammatory necrosis of the ileum and colon include activation of the pathogen recognition receptor Toll-like receptor 4 (TLR4) and decreased levels of transforming growth factor beta (TGFβ). Extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a novel damage-associated molecular pattern (DAMP), is a TLR4 ligand and plays a role in a number of inflammatory disease processes. To test the hypothesis that eNAMPT is involved in NEC, an eNAMPT-neutralizing monoclonal antibody, ALT-100, was used in a well-established animal model of NEC. Preterm Sprague-Dawley pups delivered prematurely from timed-pregnant dams were exposed to hypoxia/hypothermia and randomized to control-foster mother dam-fed rats, injected IP with saline (vehicle) 48 h after delivery; control + mAB-foster dam-fed rats, injected IP with 10 µg of ALT-100 at 48 h post-delivery; NEC-orally gavaged, formula-fed rats injected with saline; and NEC + mAb-formula-fed rats, injected IP with 10 µg of ALT-100 at 48 h. The distal ileum was processed 96 h after C-section delivery for histological, biochemical, molecular, and RNA sequencing studies. Saline-treated NEC pups exhibited markedly increased fecal blood and histologic ileal damage compared to controls (q < 0.0001), and findings significantly reduced in ALT-100 mAb-treated NEC pups (q < 0.01). Real-time PCR in ileal tissues revealed increased NAMPT in NEC pups compared to pups that received the ALT-100 mAb (p < 0.01). Elevated serum levels of tumor necrosis factor alpha (TNFα), interleukin 6 (IL-6), interleukin-8 (IL-8), and NAMPT were observed in NEC pups compared to NEC + mAb pups (p < 0.01). Finally, RNA-Seq confirmed dysregulated TGFβ and TLR4 signaling pathways in NEC pups that were attenuated by ALT-100 mAb treatment. These data strongly support the involvement of eNAMPT in NEC pathobiology and eNAMPT neutralization as a strategy to address the unmet need for NEC therapeutics.

TGF-β Family Signaling in Connective Tissue and Skeletal Diseases

The transforming growth factor β (TGF-β) family of signaling molecules, which includes TGF-βs, activins, inhibins, and numerous bone morphogenetic proteins (BMPs) and growth and differentiation factors (GDFs), has important functions in all cells and tissues, including soft connective tissues and the skeleton. Specific TGF-β family members play different roles in these tissues, and their activities are often balanced with those of other TGF-β family members and by interactions with other signaling pathways. Perturbations in TGF-β family pathways are associated with numerous human diseases with prominent involvement of the skeletal and cardiovascular systems. This review focuses on the role of this family of signaling molecules in the pathologies of connective tissues that manifest in rare genetic syndromes (e.g., syndromic presentations of thoracic aortic aneurysm), as well as in more common disorders (e.g., osteoarthritis and osteoporosis). Many of these diseases are caused by or result in pathological alterations of the complex relationship between the TGF-β family of signaling mediators and the extracellular matrix in connective tissues.

TGF Beta1 Expression Correlates with Survival and Tumor Aggressiveness of Prostate Cancer

BACKGROUND

Although biopsy Gleason score and clinical stage can be used to inform treatment decisions for prostate cancer, identifying molecular markers of tumor aggressiveness could lead to a more tailored approaches to therapy. In the present study, we investigated the association of transforming growth factor (TGF)-β1 levels and various markers of tumor aggressiveness and explore some potential mechanisms underlying the associations.

METHODS

We used human and murine prostate cancer cell lines and their respective hormone resistance sub-lines, in vitro and in vivo to examine the changes in tumor aggressiveness, as well as the pathway responsible for these changes. Furthermore, 105 prostate cancer biopsy specimens were analyzed to correlate the level of TGF-β1 with the clinical characteristics of patients.

RESULTS

Our data revealed that activated TGF-β1 signaling resulted in more aggressive tumor growth and augmented the epithelial-mesenchymal transition. Activated IL-6 signaling was associated with TGF-β1 levels and the aggressive tumor features noted in TGF-β1-positive prostate cancers in vitro and in vivo. Furthermore, the TGF-β1 levels significantly correlated with Tregs accumulation in vivo. The clinical data indicated that TGF-β1 immunoreactivity had a moderate positive correlation with IL-6 staining, advanced clinical stage, higher Gleason score, and pretreatment PSA in patients with prostate cancer.

CONCLUSIONS

TGF-β1 levels are significantly associated with aggressive prostate features. In vitro and in vivo alternations of TGF-β1 expression impacts tumor invasiveness, tumor growth rate and recruitment of immunosuppressive Treg cells in the tumor microenvironment. TGF-β1 expression may represent a clinical useful biomarker to guide prostate cancer treatment decisions.

Transgene-derived overexpression of miR-17-92 in CD8+ T-cells confers enhanced cytotoxic activity

MicroRNAs (miRs) play important roles in regulation of a variety of cell functions, including immune responses. We have previously demonstrated that miR-17-92 expression in T-cells enhances Th1 phenotype and provides a long-term protection against glioblastoma when co-expressed as a transgene in T-cells along with a chimeric antigen receptor. To further elucidate the function of miR-17-92 in tumor antigen-specific CD8(+) T-cells, we generated transgenic (Tg) mice in which CD8(+) T-cells overexpress transgene-derived miR-17-92 under the lck promoter as well as T-cell receptor specific for human gp10025-33 (Pmel-1) (miR-17-92/Pmel-Tg). CD8(+) T-cells from miR-17-92/Pmel-Tg mice demonstrated enhanced interferon (IFN)-γ production and cytotoxicity in response to the cognate antigen compared with those from control Pmel-Tg mice without the transgene for miR-17-92. In addition, miR-17-92/Pmel-Tg mouse-derived CD8(+)CD44(+) T-cells demonstrated increased frequencies of cells with memory phenotypes and IFN-γ production. We also found that miR-17-92/Pmel-Tg-derived CD8(+) T-cells expressed decreased levels of transforming growth factor (TGF)-β type II receptor (TGFBR2) on their surface, thereby resisting against suppressive effects of TGF-β1. Our findings suggest that engineering of tumor antigen-specific CD8(+) T-cells to express miR-17-92 may improve the potency of cancer immunotherapy.

TGF-β1 mediates the radiation response of prostate cancer

Radiotherapy is the main treatment modality for prostate cancer. This study investigated the role of TGF-β1 in biological sequelae and tumor regrowth following irradiation, which are critical for the clinical radiation response of prostate cancer. Human and murine prostate cancer cell lines, and corresponding hormone-refractory (HR) cells, were used to examine the radiation response by clonogenic assays in vitro and tumor growth delay in vivo. Biological changes after irradiation, including cell death and tumor regrowth, were examined by experimental manipulation of TGF-β1 signaling. The correlations among tumor radiation responses, TGF-β1 levels, and regulatory T cells (Tregs) recruitment were also evaluated using animal experiments. HR prostate cancer cells appeared more radioresistant and had higher expression of TGF-β1 compared to hormone-sensitive (HS) cells. TGF-β1 expression was positively linked to irradiation and radioresistance, as demonstrated by in vitro and in vivo experiments. Inhibition of TGF-β1 increased tumor inhibition and DNA damage after irradiation. When mice were irradiated with a sub-lethal dose, the regrowth of irradiated tumors was significantly correlated with TGF-β1 levels and Tregs accumulation in vivo. Furthermore, blocking TGF-β1 clearly attenuated Tregs accumulation and tumor regrowth following treatment. These data demonstrate that TGF-β1 is important in determining the radiation response of prostate cancer, including tumor cell killing and the tumor microenvironment. Therefore, concurrent treatment with a TGF-β1 inhibitor is a potential therapeutic strategy for increasing the radiation response of prostate cancer, particularly for more aggressive or HR cancer cells.

KEY MESSAGE

• HR prostate cancer cells appeared more radioresistant and had higher expression of TGF-β1. • TGF-β1 was positively linked to the radiation resistance of prostate cancer. • Tumor regrowth following irradiation was significantly correlated with TGF-β1 and Tregs levels. • Blocking TGF-β1 significantly attenuated RT-induced DNA repair and Tregs. • TGF-β1 inhibitor increases the radiation response of HR cancer cells.

TGFβ in T cell biology and tumor immunity: Angel or devil?

The evolutionally conserved transforming growth factor β (TGFβ) affects multiple cell types in the immune system by either stimulating or inhibiting their differentiation and function. Studies using transgenic mice with ablation of TGFβ or its receptor have revealed the biological significance of TGFβ signaling in the control of T cells. However, it is now clear that TGFβ is more than an immunosuppressive cytokine. Disruption of TGFβ signaling pathway also leads to impaired generation of certain T cell populations. Therefore, in the normal physiological state, TGFβ actively maintains T cell homeostasis and regulates T cell function. However, in the tumor microenvironment, TGFβ creates an immunosuppressive milieu that inhibits antitumor immunity. Here, we review recent advances in our understanding of the roles of TGFβ in the regulation of T cells and tumor immunity.

T cell- but not tumor cell-produced TGF-β1 promotes the development of spontaneous mammary cancer

During their development, tumors acquire multiple capabilities that enable them to proliferate, disseminate and evade immunosurveillance. A putative mechanism is through the production of the cytokine TGF-β1. We showed in our recent studies that T cell-produced TGF-β1 inhibits antitumor T cell responses to foster tumor growth raising the question of the precise function of TGF-β1 produced by tumor cells in tumor development. Here, using a transgenic model of mammary cancer, we report that deletion of TGF-β1 from tumor cells did not protect mice from tumor development. However, ablation of TGF-β1 from T cells significantly inhibited mammary tumor growth. Additionally, absence of TGF-β1 in T cells prevented tumors from advancing to higher pathological grades and further suppressed secondary tumor development in the lungs. These findings reveal T cells but not tumor cells as a critical source of TGF-β1 that promotes tumor development.

Notch activation on effector T cells increases their sensitivity to Treg cell-mediated suppression through upregulation of TGF-βRII expression

Notch proteins play an important role in embryonic development and cell-fate decisions. Notch influences also the activation and differentiation of peripheral T cells. Here, we investigated whether Notch signaling modulates the response of effector T cells to regulatory T (Treg) cells. Pre-exposure of CD4(+) CD25(-) effector T cells to the Notch ligands Delta-4 and Jagged-1, but not Delta-1, increases significantly effector T-cell sensitivity to Treg cell-mediated suppression through upregulation of TGF-βRII expression and increased levels of the phosphorylated form of the Smad 3 protein. This effect is relieved by anti-TGF-β Abs. We demonstrate that HES (hairy and enhancer of split), the main transcription factor downstream of Notch, induces strong transactivation of TGF-ßRII by binding the TGF-βRII promoter through its DNA-binding domain. Thus, the crosstalk between Notch and the TGF-β pathway leads to potentiation of the suppressive effect of Treg cells.