Mouse IL-15 Research Articles

Abstract B053: Physical activity regulates targetable transcriptomic changes in the adipose tissue of obese PDAC mice

Abstract Background: Obesity is a risk factor for pancreatic ductal adenocarcinoma (PDAC), a highly aggressive cancer with a low 5-year survival rate. The association between obesity and PDAC could be attributed to the inflammatory effects of obesity and its impact on the adipose microenvironment. Physical activity (PA) is a potential approach to counteract obesity and its associated inflammation. Moreover, a recent study revealed that exercise-induced interleukin (IL)-15 in tumors has an anti-tumor response. However, there is still limited understanding of the mechanisms underlying how PA impacts the adipose-tumor microenvironments in PDAC. In this study, we hypothesized that PA could upregulate anti-inflammatory signaling in the adipose tissue and that targeting some of these signaling pathways could be a novel therapy for obesity-associated PDAC. Methods: Transcriptomic analysis was performed on adipose tissue obtained from a genetically engineering mouse model of obesity-associated PDAC. The mice were fed an obesogenic high-fat diet and divided into groups with and without PA intervention for one month. An adipose-specific recombinant adeno-associated vector (rAAV) was generated and mouse IL-15 cDNA was subcloned into the vector. C57BL/6J mice were administered intraperitoneal injections of either the rAAV/empty or rAAV/IL-15 vectors. Three weeks after rAAV intraperitoneal injection, mice were orthotopically injected with mouse KRasG12D/Trp53−/−/PDX-1-CRE cells expressing firefly luciferase to monitor growth in vivo and expression of IL-15 in the adipose tissue was confirmed via qPCR. Results: PA intervention increased the expression of genes related to metabolic and inflammation-related pathways. The administration of a novel adipose-targeted rAAV resulted in the upregulation of IL-15 within the adipose tissue and not the tumor. Increasing IL-15 expression in the adipose tissue led to a notable delay in tumor growth in an orthotopic mouse model. Conclusions: Here, we show that PA modulates gene expression in the adipose tissue and the beneficial impact of adipose tissue molecular remodeling on anti-tumor effects. However, more studies are needed to characterize the full extent of the adipose-tumor interactions and how they can be effectively targeted for therapeutic interventions. Citation Format: Hsiang-Yin Hsueh, Valentina Pita-Grisanti, Ericka Vélez-Bonet, Lei Cao, Wei Huang, Zobeida Cruz-Monserrate. Physical activity regulates targetable transcriptomic changes in the adipose tissue of obese PDAC mice [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B053.

Preventive effects of quercetin against foot-and-mouth disease virus in vitro and in vivo by inducing type I interferon.

Foot-and-mouth disease (FMD) is an acute contagious infectious disease that affects cloven-hoofed animals. Although current emergency FMD vaccines only take effect 7 days after vaccination, antiviral agents, such as quercetin, which is a common flavonoid, could reduce the spread of FMD virus (FMDV) during outbreaks. We investigated the in vitro and in vivo antiviral effects of quercetin against FMDV. Analysis of viral copy numbers showed that quercetin had a dose-dependent inhibitory effect on FMDV at concentrations between 19.5 and 1,250 μM in porcine cells. In addition, we observed a quercetin-induced interferon (IFN)-α protein and interferon-stimulated gene (ISG) upregulation in swine cells. Enzyme-linked immunosorbent assay of sera revealed that quercetin induces the production of IFN-α, IFN-β, IFN-γ, interleukin (IL)-12, and IL-15 in mice. Inoculation of mice with quercetin or a combination of quercetin with an inactivated FMD vaccine enhanced both the survival rate and neutralizing antibody titer. Therefore, we suggest the use of quercetin as a novel and effective antiviral agent for controlling FMDV infection; however, further investigation of its application in livestock is required.

Functional roles of cytokines in infectious disease associated colorectal carcinogenesis.

Infection processes induce various soluble factors that are carcinogens in humans; therefore, research into the soluble factors of chronic disease released from cells that have been infected with parasites is warranted. Parasitic infections in host cells release high levels of IFNγ. Studies have hypothesised that parasitosis-associated carcinogenesis might be analogous to colorectal cancers developed from inflammatory bowel diseases, whereby various cytokines and chemokines are secreted during chronic inflammation. IL-18 and IL-21 are other factors that might be involved in the development of colorectal cancer in schistosomiasis patients and patients with other infections. IL-21 has profound effects on tumour growth and immunosurveillance of colitis-associated tumourigenesis, thereby emphasising its involvement in the pathogenesis of colorectal cancer. The prominent role of IL-21 in antitumour effects greatly depends on the enhanced cytolytic activity of NK cells and the pathogenic role of IL-21, which is often associated with enhanced risks of cancer and chronic inflammatory processes. As IL-15 is also related to chronic disease, it is believed to also play a role in the antitumour effect of colorectal carcinogenesis. IL-15 generates and maintains long-term CD8+ T cell immunity against T. gondii to control the infection of intracellular pathogens. The lack of IL-15 in mice contributes to the downregulation of the IFNγ-producing CD4+ T cell response against acute T. gondii infection. IL-15 induces hyperplasia and supports the progressive growth of colon cancer via multiple functions. The limited role of IL-15 in the development of NK and CD8+ T cells suggests that there may be other cytokines compensating for the loss of the IL-15 gene.

Abstract 1632: Long-term maintenance of human mature NK cells from hCD34+HSCs engraftment supported by immune humanized B-NDG hIL15 mice

Abstract Human HSC (hematopoietic stem cells) engrafted humanized mice are a powerful model that allows researchers to examine the human immune system and evaluate cellular immunotherapy in the preclinical stage. Successful reconstitution of the human immune system in B-NDG mice (a complete immunodeficient mouse model previously developed by Biocytogen) has been accomplished using CD34+ hematopoietic stem cells. However, the species barrier between human immune cells and the mouse microenvironment can obstruct human immunity acquisition, as well as innate immune function development, in the mice upon the reconstitution of immune system. To address this issue, Biocytogen has developed and validated the B-NDG hIL15 mice that combines a B-NDG mouse background and expresses human IL15 cytokine, which plays important roles in the innate and adaptive cell homeostasis, as well as peripheral immune function. The targeting strategy stipulates the insertion of CDS region of the human IL15 gene after the 5′UTR of the mouse Il15. In this work, human CD34+ hematopoietic stem cells have been successfully grafted in B-NDG hIL15 mice, to reconstitute a functional human immune system. At 4 weeks post CD34+ cell implantation, the percentage of hCD45+ cells reached over 25%, containing human T, B, and NK cells. In summary, these CD34+ reconstituted B-NDG hIL15 mice are validated to be promising tools for the efficacy study of clinically relevant therapeutic agents given the mice's long-term maintenance of human NK cells upon the reconstitution of immune system. Citation Format: Qingcong Lin, Yuting Hu, Xiaofei Zhou, Youhong Su, Yuelei Shen. Long-term maintenance of human mature NK cells from hCD34+HSCs engraftment supported by immune humanized B-NDG hIL15 mice [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1632.

Abstract 525: A novel anti-PD1-IL15 immunocytokine potentiates anti-tumor T cell activity of PD-1 checkpoint inhibition and IL-2R-beta-gamma agonism

Abstract Therapeutic antibodies targeting immune checkpoint inhibitors (ICI) such as PD-1/PD-L1 effectively expand and reactivate T cells in patients, leading to long-lasting response in multiple tumor types. However, only a fraction of patients responded to approved ICIs, majority are either resistant or quickly become refractory. Other immunotherapy modalities including immunostimulatory cytokines IL-2, IL-12 and IL-15 demonstrated clinical benefits as monotherapy or in combination with ICIs. Cytokines exhibit in general a short half-life and systemic toxicities that limit their use as the optimal doses in treating cancer. An antibody-based immunocytokine fusion such as Kadmon lead candidate KD033 (anti-PDL1/IL15) and Roche anti-PD1/CEA/FAP-IL2v can extend the half-life of cytokine and reduce systemic toxicities. In this study, a fully human single-chain variable fragment (scFv) antibody against mouse PD1 (mPD1) have been isolated from the phage display library. The variable domains of these antibodies were fused to either human IgG1a or mouse IgG2a constant domain first, and then fused to either human IL15 receptor alpha sushi domain-hIL15 complex (hSD15) or mouse IL15 receptor alpha sushi domain-mIL15 complex (mSD15). These variations of fusion have been tested in in vitro binding and functional assays, and in vivo in PD1/PDL1 resistant mouse syngeneic model LL2 (Lewis Lung Carcinoma). We demonstrated that hSD15 fusion antibody can stimulate both IL2 dependent human and murine cells growth, surprisingly, mSD15 fusion antibody can only stimulate murine cell growth. Although mSD15 fusion antibody EC50 was 10 folds better than hSD15 fusion antibody in stimulating mouse spleen cell growth in vitro, it did not show a better efficacy than hSD15 fusion antibody in LL2 model. In vivo, mSD15 fusion antibody had higher maximum tolerate dose than hSD15 fusion antibody (up to 12mg/kg). In addition, anti-mPD1/mSD15 showed better efficacy than either the mIL15 and anti-mPD1 alone or the combination of anti-mPD1 plus mIL15 in vitro and in vivo. Together these preclinical data have confirmed that PD1-IL15 could be a promising next generation IL-15 fusion for cancer immunotherapy. Citation Format: Dan Lu, Zhanna Polonskaya, Tzi-Pei Chang, Stella Martomo, Xenia Luna, Zhikai Zhang, Faical Miyara, Jeedar Patel. A novel anti-PD1-IL15 immunocytokine potentiates anti-tumor T cell activity of PD-1 checkpoint inhibition and IL-2R-beta-gamma agonism [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 525.

Interleukin-15 as a myokine: mechanistic insight into its effect on skeletal muscle metabolism.

Interleukin (IL)-15 is a cytokine with important immunological functions. It is highly expressed in skeletal muscle and is believed to be a myokine, a hypothesis supported by the rapid increase in circulating levels of IL-15 in response to exercise. Treatment with high doses of IL-15 results in metabolic adaptations such as improved insulin sensitivity and whole-body fatty acid oxidation and protection from high-fat-diet-induced obesity and insulin resistance. IL-15 secreted by contracting muscle may therefore act as an endocrine factor to improve adiposity and energy metabolism in different tissues. Most studies have used supraphysiological doses of IL-15 that do not represent circulating IL-15 in response to exercise. However, evidence shows that IL-15 levels are higher in muscle interstitium and that IL-15 might improve muscle glucose homeostasis and oxidative metabolism in an autocrine/paracrine manner. Nevertheless, how IL-15 signals in skeletal muscle to improve muscle energy metabolism is not understood completely, especially because the absence of the α subunit of the IL-15 receptor (IL-15Rα) results in a phenotype similar to that of overexpressing/oversecreting IL-15 in mice. In this article, we review the literature to propose a model for the regulation of IL-15 by the soluble form of IL-15Rα to explain why some findings in the literature seem, at first glance, to be contradictory.

Interleukin-15 suppresses gastric cancer liver metastases by enhancing natural killer cell activity in a murine model.

Interleukin (IL)-15 is a promising cytokine for cancer immunotherapy as it is a critical factor for the proliferation and activation of natural killer (NK) cells. Previous studies have suggested critical roles of IL-15 in tumor invasion and metastasis. However, the association between IL-15 and liver metastasis of gastric cancer (LMGC) remains unknown. The present study investigated the therapeutic efficacy of recombinant mouse IL-15 (rmIL-15) in murine LMGC models, in which stable green fluorescent protein (GFP)-expressing MKN45 cells (MKN45-GFP cells) were injected into the spleen parenchyma of mice for liver metastasis. At different treatments (high dose group: 2.5 µg of rmIL-15; low dose group: 0.2 µg of rmIL-15; control group: PBS), it was found that rmIL-15 decreased the formation of liver metastasis sites. Additionally, this treatment lead to improved survival of mice following tumor cell transplantation. Treatment with a high dose of rmIL-15 provided greater therapeutic efficacy by prolonged survival of the mice compared with low dose group and control group. It was found that NK cells isolated from the liver that received the high dose of rmIL-15 showed stronger cytotoxic activity compared with the other two groups on the target cells. These findings hold significant importance for the use of IL-15 as a potential adjuvant/therapeutic for liver metastasis from gastric cancer.

Interleukins 7 and 15 Maintain Human T Cell Proliferative Capacity through STAT5 Signaling.

T lymphocytes require signals from self-peptides and cytokines, most notably interleukins 7 and 15 (IL-7, IL-15), for survival. While mouse T cells die rapidly if IL-7 or IL-15 is withdrawn, human T cells can survive prolonged withdrawal of IL-7 and IL-15. Here we show that IL-7 and IL-15 are required to maintain human T cell proliferative capacity through the STAT5 signaling pathway. T cells from humanized mice proliferate better if stimulated in the presence of human IL-7 or IL-15 or if T cells are exposed to human IL-7 or IL-15 in mice. Freshly isolated T cells from human peripheral blood lose proliferative capacity if cultured for 24 hours in the absence of IL-7 or IL-15. We further show that phosphorylation of STAT5 correlates with proliferation and inhibition of STAT5 reduces proliferation. These results reveal a novel role of IL-7 and IL-15 in maintaining human T cell function, provide an explanation for T cell dysfunction in humanized mice, and have significant implications for in vitro studies with human T cells.

TGF-β induces IL-15 in hepatocytes. Is it then opposing TGFβ in a negative feedback manner? Does this mechanism play a role in liver disease?

Liver fibrogenesis is a process involving the participation of several cellular components. We described a new role for hepatocytes in the process of fibrogenesis, in which TGFbeta induces expression and secretion of CTGF, another potent profibrogenic cytokine. Recently Interleukin-15 has emerged as a new player in several models of liver damage, but its precise role has not yet been determined. Real Time PCR showed that TGFbeta induces IL-15 mRNA up to 80 fold after 24h in primary hepatocytes, and up to 10 fold in AML12 cells. Using chemical inhibitors we determined that although ALK5 activity is essential, ERK and JNK pathways cooperate in this induction. Two isoforms are expressed, differing in the length of the signal peptide. By PCR we observed induction of both splice variants of IL-15. Using siRNA we determined that Smad3 but not Smad2 is partially necessary for IL-15 mRNA induction. Software analysis of a -1,8kb region of mouse IL-15 promoter revealed binding sites for Smad3, Fast-1 and AP-1 highlighting the potential cooperation between Smad3 and AP-1 complexes. By ELISA we detected IL-15 in cell pellets but not in supernatants, indicating that IL-15 and IL-15/IL-15R complex are not secreted. Immunohistochemistry analysis of mouse and human livers revealed expression of IL-15 in hepatocytes found increased in TGFbeta transgenic mice, and in patients with liver fibrosis due to HBV, Schistosoma japonicum and gallstone bladder. Our results indicate that a new potent cytokine is induced in hepatocytes by TGFbeta. We are currently investigating the biological significance of this finding with regard to TGFbeta induced hepatocyte apoptosis, EMT and fibrotic processes.

IL-15 trans-presentation promotes human NK cell development and differentiation in vivo

The in vivo requirements for human natural killer (NK) cell development and differentiation into cytotoxic effectors expressing inhibitory receptors for self–major histocompatability complex class I (MHC-I; killer Ig-like receptors [KIRs]) remain undefined. Here, we dissect the role of interleukin (IL)-15 in human NK cell development using Rag2−/−γc−/− mice transplanted with human hematopoietic stem cells. Human NK cell reconstitution was intrinsically low in this model because of the poor reactivity to mouse IL-15. Although exogenous human IL-15 (hIL-15) alone made little improvement, IL-15 coupled to IL-15 receptor α (IL-15Rα) significantly augmented human NK cells. IL-15–IL-15Rα complexes induced extensive NK cell proliferation and differentiation, resulting in accumulation of CD16+KIR+ NK cells, which was not uniquely dependent on enhanced survival or preferential responsiveness of this subset to IL-15. Human NK cell differentiation in vivo required hIL-15 and progressed in a linear fashion from CD56hiCD16−KIR− to CD56loCD16+KIR−, and finally to CD56loCD16+KIR+. These data provide the first evidence that IL-15 trans-presentation regulates human NK cell homeostasis. Use of hIL-15 receptor agonists generates a robust humanized immune system model to study human NK cells in vivo. IL-15 receptor agonists may provide therapeutic tools to improve NK cell reconstitution after bone marrow transplants, enhance graft versus leukemia effects, and increase the pool of IL-15–responsive cells during immunotherapy strategies.

IL-15 constrains mast cell–dependent antibacterial defenses by suppressing chymase activities

Sepsis remains a global clinical problem. By using the mouse cecal ligation and puncture model of sepsis, here we identify an important aspect of mast cell (MC)-dependent, innate immune defenses against Gram-negative bacteria by demonstrating that MC protease activity is regulated by interleukin-15 (IL-15). Mouse MCs express both constitutive and lipopolysaccharide-inducible IL-15 and store it intracellularly. Deletion of Il15 in mice markedly increases chymase activities, leading to greater MC bactericidal responses, increased processing and activation of neutrophil-recruiting chemokines, and significantly higher survival rates of mice after septic peritonitis. By showing that intracellular IL-15 acts as a specific negative transcriptional regulator of a mouse MC chymase (mast cell protease-2), we provide evidence that defined MC protease activity is transcriptionally regulated by an intracellularly retained cytokine. Our results identify an unexpected breach in MC-dependent innate immune defenses against sepsis and suggest that inhibiting intracellular IL-15 in MCs may improve survival from sepsis.

Involvement of graft-derived interleukin-15 in islet allograft rejection in mice

The possibility that islets play a role in graft rejection during islet transplantation for type-1 diabetes patients holds promise for ex vivo islet manipulation and for specific anti-rejection therapy. Interleukin (IL)-15 is a T cell growth factor and chemoattractant that is expressed by non-T cells. Intragraft expression of IL-15 is elevated during acute rejection in patients and in mice, and systemic blockade of IL-15 in mice prolongs allograft survival. However, the source of IL-15 in these conditions is undetermined. Since epithelial cell-derived IL-15 promotes lymphocyte proliferation in culture, we sought to determine whether islet-derived IL-15 promotes rejection in mice.We designed antisense oligodeoxyribonucleotide molecules that target mouse IL-15. Uptake of FITC-labeled antisense molecules and efficacy of IL-15 inhibition in IFNγ-stimulated islets were evaluated. Islets exhibited typical cytoplasmatic distribution of antisense molecules and produced IL-15 levels that were comparable to non-stimulated cells. Antisense-treated islet allografts, that were transplanted across multiple minor-histocompatibility-antigen mismatched strains of mice, were accepted at a higher rate than control-antisense treated islets or untreated islets (88.9% vs. 37.5% and 20%, respectively). Our results suggest that islet-derived IL-15 may be involved in acute islet allograft rejection.

Durable cytotoxic immune responses against gp120 elicited by recombinant SV40 vectors encoding HIV-1 gp120 ± IL-15

BackgroundA vaccine that elicits durable, powerful anti-HIV immunity remains an elusive goal. In these studies we tested whether multiple treatments with viral vector-delivered HIV envelope antigen (gp120), with and without IL-15, could help to approach that goal. For this purpose, we used recombinant Tag-deleted SV40-derived vectors (rSV40s), since they do not elicit neutralizing antibody responses, and so can be given multiply without loss of transduction efficiency.MethodsSV(gp120) carried the coding sequences for HIV-1NL4-3 Env, and SV(mIL-15) carried the cDNA for mouse IL-15. Singly, and in combination, these two vectors were given monthly to BALB/cJ mice. Cytotoxic immunity and cytotoxic memory were tested in direct cytotoxicity assays using unselected effector cells. Antibody vs. gp120 was measured in a binding assay. In both cases, targets were P815 cells that were stably transfected with gp120.ResultsMultiple injections of SV(gp120) elicited powerful anti-gp120 cytolytic activity (>70% specific lysis) by unselected spleen cells. Cells from multiply-immunized mice that were rested 1 year after their last injections still showed >60% gp120-specific lysis. Anti-gp120 antibody was first detected after 2 monthly injections of SV(gp120) and remained elevated thereafter. Adding SV(mIL-15) to the immunization regimen dramatically accelerated the development of memory cytolytic responses, with ≥ 50% specific lysis seen 1 month after two treatments. IL-15 did not alter the development of antibody responses.ConclusionsThus, rSV40s encoding antigens and immunostimulatory cytokines may be useful tools for priming and/or boosting immune responses against HIV.

Alternative splicing of mouse IL-15 is due to the use of an internal splice site in exon 5

IL-15 is a pleiotropic cytokine modulating growth and differentiation of several hematopoietic cell types. Recently, we have demonstrated that mouse microglial cells, the brain macrophages, express both IL-15 and IL-15/IL-2 receptors. Based on single-cell RT-PCR data, we describe here an alternatively spliced IL-15 mRNA variant found in a small subpopulation of mouse microglia (5%, 3 out of 60 cells expressing IL-15 transcripts). PCR cycle sequencing of this larger transcript revealed the mouse homologue of the alternatively spliced exon A as it is known from the human IL-15 gene. Analysis of the corresponding mouse IL-15 gene region shows that the larger IL-15 transcript contains an yet unidentified 5′ sequence of exon 5 while the shorter transcript uses an internal splice acceptor site. The mouse exon 5A segment has a length of 136 nt (17 nt longer than the human exon A). It contains five in-frame stop codons at its 5′ end and a new translation initiation site at its 3′ end. This new start site is surrounded by a favourable Kozak consensus sequence suggesting a more efficient translation rate. Further translational control by stem–loop binding factors is inferred by a predicted RNA stem–loop structure around the start site. Insertion of exon 5A would lead to an IL-15 polypeptide with a shortened leader sequence of 26 amino acids, as compared to the 48 amino acid leader sequence encoded by the transcript lacking exon 5A. Thus, the final IL-15 protein of the two splice variants is identical; different leader sequences could, however, lead to differences in the intracellular sorting, processing and/or secretion of IL-15.