FXR Agonism with Bile Acid Mimetic Reduces Pre-Clinical Triple-Negative Breast Cancer Burden.

Bariatric surgery is associated with improved outcomes for several cancers, including breast cancer (BC), although the mechanisms mediating this protection are unknown. We hypothesized that elevated bile acid pools detected after bariatric surgery may be factors that contribute to improved BC outcomes. Patients with greater expression of the bile acid receptor FXR displayed improved survival in specific aggressive BC subtypes. FXR is a nuclear hormone receptor activated by primary bile acids. Therefore, we posited that activating FXR using an established FDA-approved agonist would induce anticancer effects. Using in vivo and in vitro approaches, we determined the anti-tumor potential of bile acid receptor agonism. Indeed, FXR agonism by the bile acid mimetic known commercially as Ocaliva ("OCA"), or Obeticholic acid (INT-747), significantly reduced BC progression and overall tumor burden in a pre-clinical model. The transcriptomic analysis of tumors in mice subjected to OCA treatment revealed differential gene expression patterns compared to vehicle controls. Notably, there was a significant down-regulation of the oncogenic transcription factor MAX (MYC-associated factor X), which interacts with the oncogene MYC. Gene set enrichment analysis (GSEA) further demonstrated a statistically significant downregulation of the Hallmark MYC-related gene set (MYC Target V1) following OCA treatment. In human and murine BC analyses in vitro, agonism of FXR significantly and dose-dependently inhibited proliferation, migration, and viability. In contrast, the synthetic agonism of another common bile acid receptor, the G protein-coupled bile acid receptor TGR5 (GPBAR1) which is mainly activated by secondary bile acids, failed to significantly alter cancer cell dynamics. In conclusion, agonism of FXR by primary bile acid memetic OCA yields potent anti-tumor effects potentially through inhibition of proliferation and migration and reduced cell viability. These findings suggest that FXR is a tumor suppressor gene with a high potential for use in personalized therapeutic strategies for individuals with BC.

Protein kinase C delta regulates mononuclear phagocytes and hinders response to immunotherapy in cancer.

Mononuclear phagocytes (MPs) play a crucial role in tissue homeostasis; however, MPs also contribute to tumor progression and resistance to immune checkpoint blockade (ICB). Targeting MPs could be an effective strategy to enhance ICB efficacy. We report that protein kinase C delta (PKCδ), a serine/threonine kinase, is abundantly expressed by MPs in human and mouse tumors. PKCδ-/- mice displayed reduced tumor progression compared to wild types, with increased response to anti-PD-1. Tumors from PKCδ-/- mice demonstrated TH1-skewed immune response including increased antigen presentation and T cell activation. Depletion of MPs in vivo altered tumor growth in control but not PKCδ-/- mice. Coinjection of PKCδ-/- M2-like macrophages with cancer cells into wild-type mice markedly delayed tumor growth and significantly increased intratumoral T cell activation compared to PKCδ+/+ controls. PKCδ deficiency reprogrammed MPs by activating type I and type II interferon signaling. Thus, PKCδ might be targeted to reprogram MPs to augment ICB efficacy.

Identification of a targetable JAK-STAT enriched androgen receptor and androgen receptor splice variant positive triple-negative breast cancer subtype.

Triple-negative breast cancer (TNBC) is an aggressive subtype with no targeted therapeutics. The luminal androgen receptor (LAR) subtype constitutes 15% of TNBC and is enriched for androgen receptor (AR) and AR target genes. Here, we show that a cohort of TNBC not only expresses AR at a much higher rate (∼80%) but also expresses AR splice variants (AR-SVs) (∼20%), further subclassifying LAR-TNBC. Higher AR and AR-SV expression and corresponding aggressive phenotypes are observed predominantly in specimens obtained from African American women. LAR TNBC specimens are enriched for interferon, Janus kinase (JAK)-signal activator and transducer (STAT), and androgen signaling pathways, which are exclusive to AR-expressing epithelial cancer cells. AR- and AR-SV-expressing TNBC cell proliferation and xenograft and patient-tumor explant growth are inhibited by AR N-terminal domain-binding selective AR degrader or by a JAK inhibitor. Biochemical analysis suggests that STAT1 is an AR coactivator. Collectively, our work identifies pharmacologically targetable TNBC subtypes and identifies growth-promoting interaction between AR and JAK-STAT signaling.

Myeloid cells in the era of cancer immunotherapy: Top 3 unanswered questions.

Myeloid cells are increasingly being recognized as central players orchestrating or suppressing antitumor immune responses. With the advent of high-resolution analytical methods such as single-cell technologies, we now appreciate the heterogeneity and complexity of the myeloid compartment in the context of cancer. Because of their highly plastic nature, targeting myeloid cells has shown promising results either as a monotherapy or in combination with immunotherapy in preclinical models and cancer patients. However, the complexity of myeloid cell cellular crosstalk and molecular networks contributes to our poor understanding of the different myeloid cell subsets in tumorigenesis, which makes targeting myeloid cells challenging. Here, we summarize varied myeloid cell subsets and their contribution to tumor progression with a main focus on mononuclear phagocytes. The top three unanswered questions challenging the field of myeloid cells and cancer in the era of cancer immunotherapy are addressed. Through these questions, we discuss how myeloid cell origin and identity influence their function and disease outcomes. Different therapeutic strategies used to target myeloid cells in cancer are also addressed. Finally, the durability of myeloid cell targeting is interrogated by examining the complexity of resultant compensatory cellular and molecular mechanisms.

Mitochondrial Role in Oncogenesis and Potential Chemotherapeutic Strategy of Mitochondrial Infusion in Breast Cancer.

Triple negative breast cancer (TNBC) is one of the most aggressive cancers diagnosed amongst women with a high rate of treatment failure and a poor prognosis. Mitochondria have been found to be key players in oncogenesis and tumor progression by mechanisms such as altered metabolism, reactive oxygen species (ROS) production and evasion of apoptosis. Therefore, mitochondrial infusion is an area of interest for cancer treatment. Studies in vitro and in vivo demonstrate mitochondrial-mediated reduction in glycolysis, enhancement of oxidative phosphorylation (OXPHOS), reduction in proliferation, and an enhancement of apoptosis as effective anti-tumor therapies. This review focuses on mitochondrial dysregulation and infusion in malignancies, such as TNBC.

Reprogramming of pancreatic adenocarcinoma immunosurveillance by a microbial probiotic siderophore.

There is increasing evidence suggesting the role of microbiome alterations in relation to pancreatic adenocarcinoma and tumor immune functionality. However, molecular mechanisms of the interplay between microbiome signatures and/or their metabolites in pancreatic tumor immunosurveillance are not well understood. We have identified that a probiotic strain (Lactobacillus casei) derived siderophore (ferrichrome) efficiently reprograms tumor-associated macrophages (TAMs) and increases CD8 + T cell infiltration into tumors that paralleled a marked reduction in tumor burden in a syngeneic mouse model of pancreatic cancer. Interestingly, this altered immune response improved anti-PD-L1 therapy that suggests promise of a novel combination (ferrichrome and immune checkpoint inhibitors) therapy for pancreatic cancer treatment. Mechanistically, ferrichrome induced TAMs polarization via activation of the TLR4 pathway that represses the expression of iron export protein ferroportin (FPN1) in macrophages. This study describes a novel probiotic based molecular mechanism that can effectively induce anti-tumor immunosurveillance and improve immune checkpoint inhibitors therapy response in pancreatic cancer.

The role of obesity and bariatric surgery-induced weight loss in breast cancer.

Obesity is a complex metabolic condition considered a worldwide public health crisis, and a deeper mechanistic understanding of obesity-associated diseases is urgently needed. Obesity comorbidities include many associated cancers and are estimated to account for 20% of female cancer deaths in the USA. Breast cancer, in particular, is associated with obesity and is the focus of this review. The exact causal links between obesity and breast cancer remain unclear. Still, interactions have emerged between body mass index, tumor molecular subtype, genetic background, and environmental factors that strongly suggest obesity influences the risk and progression of certain breast cancers. Supportive preclinical research uses various diet-induced obesity models to demonstrate that weight loss, via dietary interventions or changes in energy expenditure, reduces the onset or progression of breast cancers. Ongoing and future studies are now aimed at elucidating the underpinning mechanisms behind weight-loss-driven observations to improve therapy and outcomes in patients with breast cancer and reduce risk. This review aims to summarize the rapidly emerging literature on obesity and weight loss strategies with a focused discussion of bariatric surgery in both clinical and preclinical studies detailing the complex interactions between metabolism, immune response, and immunotherapy in the setting of obesity and breast cancer.

Response to immune checkpoint blockade improved in pre-clinical model of breast cancer after bariatric surgery.

Bariatric surgery is a sustainable weight loss approach, including vertical sleeve gastrectomy (VSG). Obesity exacerbates tumor growth, while diet-induced weight loss impairs progression. It remains unknown how bariatric surgery-induced weight loss impacts cancer progression or alters response to therapy. Using a pre-clinical model of obesity followed by VSG or diet-induced weight loss, breast cancer progression and immune checkpoint blockade therapy were investigated. Weight loss by VSG or weight-matched dietary intervention before tumor engraftment protected against obesity-exacerbated tumor progression. However, VSG was not as effective as diet in reducing tumor burden despite achieving similar weight and adiposity loss. Leptin did not associate with changes in tumor burden; however, circulating IL-6 was elevated in VSG mice. Uniquely, VSG tumors displayed elevated inflammation and immune checkpoint ligand PD-L1+ myeloid and non-immune cells. VSG tumors also had reduced T lymphocytes and markers of cytolysis, suggesting an ineffective anti-tumor microenvironment which prompted investigation of immune checkpoint blockade. While obese mice were resistant to immune checkpoint blockade, anti-PD-L1 potently impaired tumor progression after VSG through improved anti-tumor immunity. Thus, in formerly obese mice, surgical weight loss followed by immunotherapy reduced breast cancer burden. Finally, we compared transcriptomic changes in adipose tissue after bariatric surgery from patients and mouse models. A conserved bariatric surgery-associated weight loss signature (BSAS) was identified which significantly associated with decreased tumor volume. Findings demonstrate conserved impacts of obesity and bariatric surgery-induced weight loss pathways associated with breast cancer progression.

As the number of people classified as obese rises globally, so do obesity-related health risks. Studies show that people diagnosed with obesity have inflammation that contributes to tumor growth and their immune system is worse at detecting cancer cells. But weight loss is not currently used as a strategy for preventing or treating cancer. Surgical procedures for weight loss, also known as 'bariatric surgeries', are becoming increasingly popular. Recent studies have shown that individuals who lose weight after these treatments have a reduced risk of developing tumors. But how bariatric surgery directly impacts cancer progression has not been well studied: does it slow tumor growth or boost the anti-tumor immune response? To answer these questions, Sipe et al. compared breast tumor growth in groups of laboratory mice that were obese due to being fed a high fat diet. The first group of mice lost weight after undergoing a bariatric surgery in which part of their stomach was removed. The second lost the same amount of weight but after receiving a restricted diet, and the third underwent a fake surgery and did not lose any weight. The experiments found that surgical weight loss cuts breast cancer tumor growth in half compared with obese mice. But mice who lost the same amount of weight through dietary restrictions had even less tumor growth than surgically treated mice. The surgically treated mice who lost weight had more inflammation than mice in the two other groups, and had increased amounts of proteins and cells that block the immune response to tumors. Giving the surgically treated mice a drug that enhances the immune system's ability to detect and destroy cancer cells reduced inflammation and helped shrink the mice's tumors. Finally, Sipe et al. identified 54 genes which were turned on or off after bariatric surgery in both mice and humans, 11 of which were linked with tumor size. These findings provide crucial new information about how bariatric surgery can impact cancer progression. Future studies could potentially use the conserved genes identified by Sipe et al. to develop new ways to stimulate the anti-cancer benefits of weight loss without surgery.

The pancreatic cancer immune tumor microenvironment is negatively remodeled by gemcitabine while TGF-ß receptor plus dual checkpoint inhibition maintains antitumor immune cells.

Pancreatic ductal adenocarcinoma (PDA) tumors have a highly immunosuppressive desmoplastic tumor microenvironment (TME) where immune checkpoint inhibition (ICI) therapy has been exceptionally ineffective. Transforming growth factor-ß (TGF-ß) receptor activation leads to cancer and immune cell proliferation and phenotype, and cytokine production leading to tumor progression and worse overall survival in PDA patients. We hypothesized that TGF-ß receptor inhibition may alter PDA progression and antitumor immunity in the TME. Here, we used a syngeneic preclinical murine model of PDA to explore the impact of TGF-ß pathway inhibitor galunisertib (GAL), dual checkpoint immunotherapy (anti-PD-L1 and CTLA-4), the chemotherapy gemcitabine (GEM), and their combinations on antitumor immune responses. Blockade of TGF-ß and ICI in immune-competent mice bearing orthotopically injected murine PDA cells significantly inhibited tumor growth and was accompanied by antitumor M1 macrophage infiltration. In contrast, GEM treatment resulted in increased PDA tumor growth, decreased antitumor M1 macrophages, and decreased cytotoxic CD8+ T cell subpopulation compared to control mice. Together, these findings demonstrate the ability of TGF-ß inhibition with GAL to prime antitumor immunity in the TME and the curative potential of combining GAL with dual ICI. These preclinical results indicate that targeted inhibition of TGF-ß may enhance the efficacy of dual immunotherapy in PDA. Optimal manipulation of the immune TME with non-ICI therapy may enhance therapeutic efficacy.

PKC agonism restricts innate immune suppression, promotes antigen cross-presentation and synergizes with agonistic CD40 antibody therapy to activate CD8+ T cells in breast cancer.

Myeloid-derived suppressor cells (MDSCs) are an immature innate cell population that expands in pathological conditions such as cancer and suppresses T cells via production of immunosuppressive factors. Conversely, efficient cytotoxic T cell priming is dependent on the ability of antigen-presenting cells (APCs) to cross-present tumor antigens to CD8+ T cells, a process that requires a specific subtype of dendritic cells (DCs) called conventional DC1 (cDC1) which are often dysfunctional in cancer. One way to activate cDC1 is ligation of CD40 which is abundantly expressed by myeloid cells and its agonism leads to myeloid cell activation. Thus, targeting MDSCs while simultaneously expanding cross-presenting DCs represents a promising strategy that, when combined with agonistic CD40, may result in long-lasting protective immunity. In this study, we investigated the effect of PKC agonists PEP005 and prostratin on MDSC expansion, differentiation, and recruitment to the tumor microenvironment. Our findings demonstrate that PKC agonists decreased MDSC expansion from hematopoietic progenitors and induced M-MDSC differentiation to an APC-like phenotype that expresses cDC1-related markers via activation of the p38 mitogen-activated protein kinase (MAPK) pathway. Simultaneously, PKC agonists favored cDC1 expansion at the expense of cDC2 and plasmacytoid DCs (pDC). Functionally, PKC agonists blunted MDSC suppressive activity and enhanced MDSC cross-priming capacity both in vitro and in vivo. Finally, combination of PKC agonism with agonistic CD40 mAb resulted in a marked reduction in tumor growth with a significant increase in intratumoral activated CD8+ T cells and tissue-resident memory CD8+ T cells in a syngeneic breast cancer mouse model. In sum, this work proposes a novel promising strategy to simultaneously target MDSCs and promote APC function that may have highly impactful clinical relevance in cancer patients.

TGF-ß Alters the Proportion of Infiltrating Immune Cells in a Pancreatic Ductal Adenocarcinoma.

PURPOSE: Immunotherapy, such as checkpoint inhibitors against anti-programmed death-ligand 1 (PD-L1), has not been successful in treating patients with pancreatic ductal adenocarcinoma (PDAC). Tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), dendritic cells (DCs), and the TGF-ß cytokine are critical in anti-cancer immunity. We hypothesized that TGF-ß enhances the immunosuppressive effects of TAM, MDSC, and DC presence in tumors. METHODS: Using a murine PDAC cell line derived from a genetically engineered mouse model, we orthotopically implanted treated cells plus drug embedded in Matrigel into immunocompetent mice. Treatments included saline control, TGF-ß1, or a TGF-ß receptor 1 small molecule inhibitor, galunisertib. We investigated TAM, MDSC, DC, and TAM PD-L1 expression with flow cytometry in tumors. Separately, we used the TIMER2.0 database to analyze TAM and PD-L1 gene expression in human PDAC tumors in TCGA database. RESULTS: TGF-ß did not alter MDSC or DC frequencies in the primary tumors. However, in PDAC metastases to the liver, TGF-ß decreased the proportion of MDSCs (P=0.022) and DCs (P=0.005). TGF-ß significantly increased the percent of high PD-L1 expressing TAMs (32 ± 6 % vs. 12 ± 5%, P=0.013) but not the proportion of TAMs in primary and metastatic tumors. TAM PD-L1 gene expression in TCGA PDAC database was significantly correlated with tgb1 and tgfbr1 gene expression (P<0.01). CONCLUSIONS: TGF-ß is important in PDAC anti-tumor immunity, demonstrating context-dependent impact on immune cells. TGF-ß has an overall immunosuppressive effect mediated by TAM PD-L1 expression and decreased presence of DCs. Future investigations will focus on enhancing anti-cancer immune effects of TGF-ß receptor inhibition.

Immune checkpoint blockade reprograms systemic immune landscape and tumor microenvironment in obesity-associated breast cancer.

Immune checkpoint blockade (ICB) has improved outcomes in some cancers. A major limitation of ICB is that most patients fail to respond, which is partly attributable to immunosuppression. Obesity appears to improve immune checkpoint therapies in some cancers, but impacts on breast cancer (BC) remain unknown. In lean and obese mice, tumor progression and immune reprogramming were quantified in BC tumors treated with anti-programmed death-1 (PD-1) or control. Obesity augments tumor incidence and progression. Anti-PD-1 induces regression in lean mice and potently abrogates progression in obese mice. BC primes systemic immunity to be highly responsive to obesity, leading to greater immunosuppression, which may explain greater anti-PD-1 efficacy. Anti-PD-1 significantly reinvigorates antitumor immunity despite persistent obesity. Laminin subunit beta-2 (Lamb2), downregulated by anti-PD-1, significantly predicts patient survival. Lastly, a microbial signature associated with anti-PD-1 efficacy is identified. Thus, anti-PD-1 is highly efficacious in obese mice by reinvigorating durable antitumor immunity. VIDEO ABSTRACT.

Role of TGF-ß in pancreatic ductal adenocarcinoma progression and PD-L1 expression.

PURPOSE: The transforming growth factor-beta (TGF-ß) pathway plays a paradoxical, context-dependent role in pancreatic ductal adenocarcinoma (PDAC): a tumor-suppressive role in non-metastatic PDAC and a tumor-promotive role in metastatic PDAC. We hypothesize that non-SMAD-TGF-ß signaling induces PDAC progression. METHODS: We investigated the expression of non-SMAD-TGF-ß signaling proteins (pMAPK14, PD-L1, pAkt and c-Myc) in patient-derived tissues, cell lines and an immunocompetent mouse model. Experimental models were complemented by comparing the signaling proteins in PDAC specimens from patients with various survival intervals. We manipulated models with TGF-ß, gemcitabine (DNA synthesis inhibitor), galunisertib (TGF-ß receptor inhibitor) and MK-2206 (Akt inhibitor) to investigate their effects on NF-κB, ß-catenin, c-Myc and PD-L1 expression. PD-L1 expression was also investigated in cancer cells and tumor associated macrophages (TAMs) in a mouse model. RESULTS: We found that tumors from patients with aggressive PDAC had higher levels of the non-SMAD-TGF-ß signaling proteins pMAPK14, PD-L1, pAkt and c-Myc. In PDAC cells with high baseline ß-catenin expression, TGF-ß increased ß-catenin expression while gemcitabine increased PD-L1 expression. Gemcitabine plus galunisertib decreased c-Myc and NF-κB expression, but induced PD-L1 expression in some cancer models. In mice, gemcitabine plus galunisertib treatment decreased metastases (p = 0.018), whereas galunisertib increased PD-L1 expression (p < 0.0001). In the mice, liver metastases contained more TAMs compared to the primary pancreatic tumors (p = 0.001), and TGF-ß increased TAM PD-L1 expression (p < 0.05). CONCLUSIONS: In PDAC, the non-SMAD-TGF-ß signaling pathway leads to more aggressive phenotypes, TAM-induced immunosuppression and PD-L1 expression. The divergent effects of TGF-ß ligand versus receptor inhibition in tumor cells versus TAMs may explain the TGF-ß paradox. Further evaluation of each mechanism is expected to lead to the development of targeted therapies.

A conditional mouse expressing an activating mutation in NRF2 displays hyperplasia of the upper gastrointestinal tract and decreased white adipose tissue.

Activation of the nuclear factor (erythroid-derived 2)-like 2 (NFE2L2 or NRF2) transcription factor is a critical and evolutionarily conserved cellular response to oxidative stress, metabolic stress, and xenobiotic insult. Deficiency of NRF2 results in hypersensitivity to a variety of stressors, whereas its aberrant activation contributes to several cancer types, most commonly squamous cell carcinomas of the esophagus, oral cavity, bladder, and lung. Between 10% and 35% of patients with squamous cell carcinomas display hyperactive NRF2 signaling, harboring activating mutations and copy number amplifications of the NFE2L2 oncogene or inactivating mutations or deletions of KEAP1 or CUL3, the proteins of which co-complex to ubiquitylate and degrade NRF2 protein. To better understand the role of NRF2 in tumorigenesis and more broadly in development, we engineered the endogenous Nfe2l2 genomic locus to create a conditional mutant LSL-Nrf2E79Q mouse model. The E79Q mutation, one of the most commonly observed NRF2-activating mutations in human squamous cancers, codes for a mutant protein that does not undergo KEAP1/CUL3-dependent degradation, resulting in its constitutive activity. Expression of NRF2 E79Q protein in keratin 14 (KRT14)-positive murine tissues resulted in hyperplasia of squamous cell tissues of the tongue, forestomach, and esophagus, a stunted body axis, decreased weight, and decreased visceral adipose depots. RNA-seq profiling and follow-up validation studies of cultured NRF2E79Q murine esophageal epithelial cells revealed known and novel NRF2-regulated transcriptional programs, including genes associated with squamous cell carcinoma (e.g. Myc), lipid and cellular metabolism (Hk2, Ppard), and growth factors (Areg, Bmp6, Vegfa). These data suggest that in addition to decreasing adipogenesis, KRT14-restricted NRF2 activation drives hyperplasia of the esophagus, forestomach, and tongue, but not formation of squamous cell carcinoma. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

FTY720 Regulates Mitochondria Biogenesis in Dendritic Cells to Prevent Kidney Ischemic Reperfusion Injury.

Dendritic cells (DCs) are central in regulating immune responses of kidney ischemia-reperfusion injury (IRI), and strategies to alter DC function may provide new therapeutic opportunities. Sphingosine 1-phosphate (S1P) modulates immunity through binding to its receptors (S1P1-5), and protection from kidney IRI occurs in mice treated with S1PR agonist, FTY720 (FTY). We tested if ex vivo propagation of DCs with FTY could be used as cellular therapy to limit the off-target effects associated with systemic FTY administration in kidney IRI. DCs have the ability of regulate innate and adaptive responses and we posited that treatment of DC with FTY may underlie improvements in kidney IRI. Herein, it was observed that treatment of bone marrow derived dendritic cells (BMDCs) with FTY induced mitochondrial biogenesis, FTY-treated BMDCs (FTY-DCs) showed significantly higher oxygen consumption rate and ATP production compared to vehicle treated BMDCs (Veh-DCs). Adoptive transfer of FTY-DCs to mice 24 h before or 4 h after IRI significantly protected the kidneys from injury compared to mice treated with Veh-DCs. Additionally, allogeneic adoptive transfer of C57BL/6J FTY-DCs into BALB/c mice equally protected the kidneys from IRI. FTY-DCs propagated from S1pr1-deficient DCs derived from CD11cCreS1pr1fl/fl mice as well as blunting mitochondrial oxidation in wildtype (WT) FTY-DCs prior to transfer abrogated the protection observed by FTY-DCs. We queried if DC mitochondrial content alters kidney responses after IRI, a novel but little studied phenomenon shown to be integral to regulation of the immune response. Transfer of mitochondria rich FTY-DCs protects kidneys from IRI as transferred FTY-DCs donated their mitochondria to recipient splenocytes (i.e., macrophages) and prior splenectomy abrogated this protection. Adoptive transfer of FTY-DCs either prior to or after ischemic injury protects kidneys from IRI demonstrating a potent role for donor DC-mitochondria in FTY's efficacy. This is the first evidence, to our knowledge, that DCs have the potential to protect against kidney injury by donating mitochondria to splenic macrophages to alter their bioenergetics thus making them anti-inflammatory. In conclusion, the results support that ex vivo FTY720-induction of the regulatory DC phenotype could have therapeutic relevance that can be preventively infused to reduce acute kidney injury.

Friend or Foe? Recent Strategies to Target Myeloid Cells in Cancer.

The tumor microenvironment (TME) is a complex network of epithelial and stromal cells, wherein stromal components provide support to tumor cells during all stages of tumorigenesis. Among these stromal cell populations are myeloid cells, which are comprised mainly of tumor-associated macrophages (TAM), dendritic cells (DC), myeloid-derived suppressor cells (MDSC), and tumor-associated neutrophils (TAN). Myeloid cells play a major role in tumor growth through nurturing cancer stem cells by providing growth factors and metabolites, increasing angiogenesis, as well as promoting immune evasion through the creation of an immune-suppressive microenvironment. Immunosuppression in the TME is achieved by preventing critical anti-tumor immune responses by natural killer and T cells within the primary tumor and in metastatic niches. Therapeutic success in targeting myeloid cells in malignancies may prove to be an effective strategy to overcome chemotherapy and immunotherapy limitations. Current therapeutic approaches to target myeloid cells in various cancers include inhibition of their recruitment, alteration of function, or functional re-education to an antitumor phenotype to overcome immunosuppression. In this review, we describe strategies to target TAMs and MDSCs, consisting of single agent therapies, nanoparticle-targeted approaches and combination therapies including chemotherapy and immunotherapy. We also summarize recent molecular targets that are specific to myeloid cell populations in the TME, while providing a critical review of the limitations of current strategies aimed at targeting a single subtype of the myeloid cell compartment. The goal of this review is to provide the reader with an understanding of the critical role of myeloid cells in the TME and current therapeutic approaches including ongoing or recently completed clinical trials.

Transient Intermittent Hyperglycemia Accelerates Atherosclerosis by Promoting Myelopoiesis.

RATIONALE: Treatment efficacy for diabetes mellitus is largely determined by assessment of HbA1c (glycated hemoglobin A1c) levels, which poorly reflects direct glucose variation. People with prediabetes and diabetes mellitus spend >50% of their time outside the optimal glucose range. These glucose variations, termed transient intermittent hyperglycemia (TIH), appear to be an independent risk factor for cardiovascular disease, but the pathological basis for this association is unclear. OBJECTIVE: To determine whether TIH per se promotes myelopoiesis to produce more monocytes and consequently adversely affects atherosclerosis. METHODS AND RESULTS: To create a mouse model of TIH, we administered 4 bolus doses of glucose at 2-hour intervals intraperitoneally once to WT (wild type) or once weekly to atherosclerotic prone mice. TIH accelerated atherogenesis without an increase in plasma cholesterol, seen in traditional models of diabetes mellitus. TIH promoted myelopoiesis in the bone marrow, resulting in increased circulating monocytes, particularly the inflammatory Ly6-Chi subset, and neutrophils. Hematopoietic-restricted deletion of S100a9, S100a8, or its cognate receptor Rage prevented monocytosis. Mechanistically, glucose uptake via GLUT (glucose transporter)-1 and enhanced glycolysis in neutrophils promoted the production of S100A8/A9. Myeloid-restricted deletion of Slc2a1 (GLUT-1) or pharmacological inhibition of S100A8/A9 reduced TIH-induced myelopoiesis and atherosclerosis. CONCLUSIONS: Together, these data provide a mechanism as to how TIH, prevalent in people with impaired glucose metabolism, contributes to cardiovascular disease. These findings provide a rationale for continual glucose control in these patients and may also suggest that strategies aimed at targeting the S100A8/A9-RAGE (receptor for advanced glycation end products) axis could represent a viable approach to protect the vulnerable blood vessels in diabetes mellitus. Graphic Abstract: A graphic abstract is available for this article.

Immunometabolism: From basic mechanisms to translation.

Immunometabolism has emerged as a major mechanism central to adaptive and innate immune regulation. From early observations that inflammatory cytokines were induced in obese adipose tissue and that these cytokines contributed to metabolic disease, it was clear that metabolism and the immunological state are inextricably linked. With a second research wave arising from studies in cancer metabolism to also study the intrinsic metabolic pathways of immune cells themselves and how those pathways influence cell fate and function, immunometabolism is a rapidly maturing area of research. Several key themes and goals drive the field. There is abundant evidence that metabolic pathways are closely tied to cell signaling and differentiation which leads different subsets of immune cells to adopt unique metabolic programs specific to their state and environment. In this way, metabolic signaling drives cell fate. It is also apparent that microenvironment greatly influences cell metabolism. Immune cells adopt programs specific for the tissues where they infiltrate and reside. Ultimately, a central goal of the field is to apply immunometabolism findings to the discovery of novel therapeutic strategies in a wide range of diseases, including cancer, autoimmunity, and metabolic syndrome. This review summarizes these facets of immunometabolism and highlights opportunities for clinical translation.

Microbiome, bile acids, and obesity: How microbially modified metabolites shape anti-tumor immunity.

Bile acids (BAs) are known facilitators of nutrient absorption but recent paradigm shifts now recognize BAs as signaling molecules regulating both innate and adaptive immunity. Bile acids are synthesized from cholesterol in the liver with subsequent microbial modification and fermentation adding complexity to pool composition. Bile acids act on several receptors such as Farnesoid X Receptor and the G protein-coupled BA receptor 1 (TGR5). Interestingly, BA receptors (BARs) are expressed on immune cells and activation either by BAs or BAR agonists modulates innate and adaptive immune cell populations skewing their polarization toward a more tolerogenic anti-inflammatory phenotype. Intriguingly, recent evidence also suggests that BAs promote anti-tumor immune response through activation and recruitment of tumoricidal immune cells such as natural killer T cells. These exciting findings have redefined BA signaling in health and disease wherein they may suppress inflammation on the one hand, yet promote anti-tumor immunity on the other hand. In this review, we provide our readers with the most recent understanding of the interaction of BAs with the host microbiome, their effect on innate and adaptive immunity in health and disease with a special focus on obesity, bariatric surgery-induced weight loss, and immune checkpoint blockade in cancer.

Reversal of obesity-driven aggressiveness of endometrial cancer by metformin.

BACKGROUND: Obesity and diabetes are associated with increased risk and worse outcomes for endometrial cancer. Metformin is a widely prescribed generic drug for the treatment of type II diabetes and metabolic syndrome and may also have anti-tumorigenic effects. Thus, we assessed the metabolic anti-tumorigenic effects of metformin in (1) human endometrial cancer cell lines under varying glucose concentrations, and (2) a novel genetically engineered mouse model of endometrioid endometrial cancer under obese and lean conditions. METHODS: The effects of metformin on cytotoxicity, apoptosis, cell cycle progression, and the AMPK/mTOR/S6 and MAPK pathways were assessed in ECC-1 and Ishikawa cells under low, normal and high glucose conditions. The impact of metformin treatment on tumor growth under obese and lean conditions was evaluated using a novel LKB1fl/fl p53fl/fl mouse model of endometrial cancer. Global, untargeted metabolomics was used to identify (1) obesity-associated differences between endometrial tumors and (2) the obesity-dependent effects of metformin in the endometrial tumors. RESULTS: Hypoglycemic conditions significantly enhanced the sensitivity of the cells to metformin in regards to its anti-proliferative and apoptotic effects, as compared to hyperglycemic and normal glucose conditions. Metformin inhibited tumor growth in both the obese and lean mice, which metformin-induced inhibition of tumor progression in obese mice was significantly greater than in lean mice. Metabolomic profiling in endometrial cancer tissues revealed significant differences between obese- and lean-mice. Enhanced energy metabolism was seen in obese- versus lean-mice as evidenced by increases in glycolytic and oxidative phosphorylation intermediates. In addition, dramatic increases in lipid biosynthesis and lipid peroxidation were found in the obese- versus lean-mice, whereas metformin obviously reversed the obesity-driven upregulation of lipid and protein biosynthesis in the obese mice. CONCLUSIONS: The obese state promoted tumor aggressiveness in the LKB1fl/fl p53fl/fl mouse model, accompanied by increases in energy metabolism, lipid biosynthesis, and markers of lipid peroxidation. Metformin had increased efficacy against endometrial cancer in obese versus lean mice and reversed the detrimental metabolic effects of obesity in the endometrial tumors. Taken together, it is likely that the unique metabolic milieu underlies metformin's improved efficacy in treating endometrial cancer which develop in an obese host environment.