Biology subjects

Lesch, M. L.

Publications and source records attributed to Lesch, M. L..

4 recordsLinked to original sources

bioRxiv2025

Local delivery of SBRT and IL-12 to Murine PDAC Tumors Modulates Hematopoiesis

BackgroundStandard of care therapies such as radiotherapy and chemotherapy have shown little efficacy against pancreatic ductal adenocarcinoma (PDAC). Immunotherapy is a newly emerging form of treatment that has shown promise; however, toxic systemic effects resulted in limited use in the clinic. Shifting from systemic to local delivery of cancer therapeutics reduces adverse systemic effects and increases response rates in multiple malignancies. Importantly, the effects of tumor-targeted therapies on distal tissues, such as the bone marrow, have not been thoroughly investigated. MethodsUsing a murine model of PDAC, we treated tumors with targeted stereotactic body radiation therapy (SBRT) and intratumoral interleukin-12 (IL-12). 13 days-13 months after tumor injection, the cells in the tumor, blood, and bone marrow were analyzed for therapy-induced changes. Hematopoietic cell numbers and lymphocytes were quantified by flow cytometry, and cytokine levels were quantified by enzyme-linked immunosorbent assays (ELISAs). ResultsWe demonstrated that although SBRT/IL-12 delivered locally to PDAC tumors successfully eradicated primary disease, it also induced significant acute and long-term effects in the bone marrow. Within days of intratumoral SBRT/IL-12 treatment, we observed acute lymphopenia in the blood, accompanied by an immunostimulatory response in the bone marrow characterized by an increase in hematopoiesis. Long-term effects included a decrease in hematopoietic stem cells (HSCs) and skewing toward a myeloid lineage bias, which could indicate premature aging of the HSC population. ConclusionsThese findings demonstrate that despite being locally delivered to the tumor, SBRT/IL-12 therapy exerts significant effects on the distal bone marrow, reinforcing the need for further investigations into the long-term systemic immunological outcomes of localized cancer treatments. Key MessagesWhat is already known on this topic: Systemic cancer therapies used to combat pancreatic ductal adenocarcinoma (PDAC) often induce toxic systemic effects. Local delivery of radiation and immunotherapy reduces adverse effects; however, the systemic spread of these therapies and the resulting effects on distal tissues such as the bone marrow have yet to be elucidated. What this study adds: Intratumoral delivery of stereotactic body radiation therapy (SBRT) and interleukin-12 (IL-12) augment hematopoiesis in the bone marrow soon after treatment and induce long-term alterations in the hematopoietic stem cells (HSCs). These effects are mainly a result of IL-12 that is transiently increased in the bone marrow after treatment. How this study might affect research, practice, or policy: Targeted SBRT/IL-12 therapy induces long-term systemic effects on the bone marrow, indicating the need for further investigation of the systemic spread of locally delivered therapeutics.

immunology↗

bioRxiv2025

Improving SBRT by re-wiring immunosuppressive neutrophils in murine pancreatic ductal adenocarcinoma

Radiation is used to treat pancreatic ductal adenocarcinoma (PDAC) in the locally-advanced setting. Stereotactic body radiation therapy (SBRT), in particular, has shown improved outcomes against conventional RT in a number of clinical trials. One key cell type involved in the response to RT are neutrophils. These innate immune cells are the first responders to tissue damage and infiltrate irradiated tumors in high numbers to rectify injury. Neutrophils typically possess an immunosuppressive, wound healing phenotype in this scenario, which allows the tumor to recover and actively suppress immunological efforts to eradicate the disease. Here, we aimed to elucidate the role of neutrophils in a murine model of PDAC treated with SBRT. Mice harboring PDAC tumors were treated with targeted SBRT and neutrophils were determined to be significantly increased in the tissue when compared to unirradiated controls. Additionally, phenotypic analysis determined that these cells were largely immunosuppressive and depletion studies confirmed they played a key role in acquired radioresistance in our model. In order to establish whether these infiltrating cells could be re-wired to contribute to anti-tumor immunity, we utilized a novel combination therapy consisting of SBRT and microspheres containing recombinant IL-12 to attempt to repolarize these cells. Transcriptomic analysis confirmed intratumoral neutrophils underwent considerable changes indicative of an immunostimulatory, anti-tumor phenotype following treatment. Moreover, depleting these cells resulted in a loss of treatment efficacy, suggesting that neutrophil re-wiring was vital for the therapeutic outcome. This study highlights neutrophils as key players in SBRT and IL-12 treatment and confirms they can act as a double-edged sword depending on the treatment employed.

immunology↗

bioRxiv2023

Elevated Lactate in Acute Myeloid Leukemia Bone Marrow Microenvironment Dysfunction, with a Dual Role of GPR81 in Macrophage Polarization and Leukemia Cell Growth

Interactions between acute myeloid leukemia (AML) and the bone marrow microenvironment (BMME) are critical to leukemia progression and chemoresistance. In the solid tumor microenvironment, altered metabolite levels contribute to cancer progression. We performed a metabolomic analysis of AML patient bone marrow serum, revealing increased metabolites compared to age- and sex-matched controls. The most highly elevated metabolite in the AML BMME was lactate. Lactate signaling in solid tumors induces immunosuppressive tumor-associated macrophages and correlates with poor prognosis. This has not yet been studied in the leukemic BMME. Herein, we describe the role of lactate in the polarization of leukemia-associated macrophages (LAMs). Using a murine AML model of blast crisis chronic myelogenous leukemia (bcCML), we characterize the suppressive phenotype of LAMs by surface markers, transcriptomics, and cytokine profiling. Then, mice genetically lacking GPR81, the extracellular lactate receptor, were used to demonstrate GPR81 signaling as a mechanism of both the polarization of LAMs and the direct support of leukemia cells. Furthermore, elevated lactate diminished the function of hematopoietic progenitors and reduced stromal support for normal hematopoiesis. We report microenvironmental lactate as a mechanism of AML-induced immunosuppression and leukemic progression, thus identifying GPR81 signaling as an exciting and novel therapeutic target for treating this devastating disease.

pathology↗

bioRxiv2023

Local Delivery of SBRT and IL12 by mRNA Technology Overcomes Immunosuppressive Barriers to Eliminate Pancreatic Cancer

The immunosuppressive milieu in pancreatic cancer (PC) is a significant hurdle to treatments, resulting in survival statistics that have barely changed in 5 decades. Here we present a combination treatment consisting of stereotactic body radiation therapy (SBRT) and IL-12 mRNA lipid nanoparticles delivered directly to pancreatic murine tumors. This treatment was effective against primary and metastatic models, achieving cures in both settings. IL-12 protein concentrations were transient and localized primarily to the tumor. Depleting CD4 and CD8 T cells abrogated treatment efficacy, confirming they were essential to treatment response. Single cell RNA sequencing from SBRT/IL-12 mRNA treated tumors demonstrated not only a complete loss of T cell exhaustion, but also an abundance of highly proliferative and effector T cell subtypes. SBRT elicited T cell receptor clonal expansion, whereas IL-12 licensed these cells with effector function. This is the first report demonstrating the utility of SBRT and IL-12 mRNA in PC. Statement of significanceThis study demonstrates the use of a novel combination treatment consisting of radiation and immunotherapy in murine pancreatic tumors. This treatment could effectively treat local and metastatic disease, suggesting it may have the potential to treat a cancer that has not seen a meaningful increase in survival in 5 decades.

cancer biology↗