The extracellular forms of the IL-1 cytokines are active through binding to specific receptors on the surface of target cells. IL-1 ligands bind to the extracellular portion of their ligand-binding receptor chain. For signaling to take place, a non-binding accessory chain is recruited into a heterotrimeric complex. The intracellular approximation of the Toll-IL-1-receptor (TIR) domains of the 2 receptor chains is the event that initiates signaling. The family of IL-1 receptors (IL-1R) includes 10 structurally related members, and the distantly related soluble protein IL-18BP that acts as inhibitor of the cytokine IL-18. Over the years the receptors of the IL-1 family have been known with many different names, with significant confusion. Thus, we will use here a recently proposed unifying nomenclature. The family includes several ligand-binding chains (IL-1R1, IL-1R2, IL-1R4, IL-1R5, and IL-1R6), 2 types of accessory chains (IL-1R3, IL-1R7), molecules that act as inhibitors of signaling (IL-1R2, IL-1R8, IL-18BP), and 2 orphan receptors (IL-1R9, IL-1R10). In this review, we will examine how the receptors of the IL-1 family regulate the inflammatory and anti-inflammatory functions of the IL-1 cytokines and are, more at large, involved in modulating defensive and pathological innate immunity and inflammation. Regulation of the IL-1/IL-1R system in the brain will be also described, as an example of the peculiarities of organ-specific modulation of inflammation.

Cancer remains to be a leading cause of death worldwide, accounting for almost 10 million deaths in 2018. Radiation therapy (RT) is a common nonsurgical treatment in the management of patients with cancer that reduces disease recurrence and improves overall survival. However, preclinical RT modeling for accelerated bench-to-bedside translation of combination therapies is largely missing. While genetically engineered mouse models (GEMM) faithfully recapitulate human disease, conventional linear particle accelerator systems, commonly utilized in clinical settings, are not suited for state-of-the-art, imageguided targeted RT (IGRT) of these murine autochthonous tumors. Thus, we employed the CyberKnife (Accuray) platform for IGRT of GEMM-derived non-small cell lunger cancer (NSCLC) lesions. The CyberKnife (CK) is a stereotactic radiosurgery system (SRS) delivering high-dose RT precisely to the target area with minimal damage to the surrounding tissues based on intra-fraction image-guidance.Material and methods: GEMM-derived NSCLC flank tumors driven by oncogenic Kras (Kras LSL-G12D/+ ) and deletion of Tp53 (Trp53 fl/fl ) were irradiated using the CK RT platform.We applied IGRT of 2, 4, 6, and 8 Gy using field sizes of 5 to 12.5 mm to average gross tumor volumes (GTV) of 0.9 cm 3 (minimal 0.03 cm 3 ) using Xsight Spine Tracking (Accuray) spine-based tumor localization. Results:We found that a 0 mm planning target volume (PTV) margin is sufficient for IGRT of murine tumors using the CK. Furthermore, we analyzed the impact of CK-mediated IGRT on tumor infiltrating leukocytes by flow cytometry. We observed that higher RT doses (6-8 Gy) decreased absolute cell numbers of lymphocytes and myeloid cells by approximately half compared to low doses (2-4 Gy) or mock treated tumors within one hour, but even with low dose RT (2 Gy) tumor infiltrating leukocytes (TIL) were found to be reduced after 8 to 24 hours and recovered partly after 3 days. Conclusion:In summary, we here demonstrate that the CK RT system allows for targeted IGRT of murine tumors with high precision and thus constitutes a novel promising platform for translational mouse RT studies, particularly performed in a longitudinal multimodal manner.

The synergy of modern immunotherapeutics and radiation has proven to be a promising strategy to combat cancer. However, fundamental questions regarding the underlying mechanisms of these therapies are unanswered. While clinical studies have demonstrated that radiation can potentially boost immune cell infiltration and tumor immunogenicity, the clinicians’ aim to use radiation to improve immune cell infiltration and turn so called ‘cold’ tumors with little infiltration into ‘hot’ tumors lacks mechanistic research data until today. We hypothesize that alterations of the tumor immune cell composition result from modified endothelial adhesion receptor expression mediating immune cell recruitment from the blood. Thus, in order to investigate the tumor vascular endothelium, we quantified infiltrating immune cells and examined the regulation of endothelial adhesion ligands following different fractionations of radiation. We applied two different radiation doses: 1x10Gy (a dose thought to improve immunogenicity), and 1x2Gy (conventional/normofractionation), analyzed immune cell infiltration via flow cytometry, and investigated the expression of endothelial molecules like ICAM‐1, ICAM‐2, VCAM‐1, E‐selectin, and P‐selectin using real time PCR and histology‐based approaches in the tumor and healthy vasculature. We analyzed transplantable lung tumors of Kras;Trp53 mutant mice 1h, 4h, 8h, 24h, 3d, 5d, and 8d after radiation. Importantly, we observed a generalized decrease of tissue immune cells within the first 24h with recovering populations at day 3 after radiation in all groups. Furthermore, we found that the expression of some endothelial adhesion receptors changes in a dose‐dependent manner, but others are not affected. For instance, ICAM‐2 remains unchanged in both groups, but tumor vasculature shows a rapid upregulation of E‐selectin within the first hour after radiation, followed by a downregulation and a second increase after 2–3 days. The lower fractions (2Gy) elicit an augmented upregulation of VCAM‐1 after 24h peaking at day 3. This is of particular interest as VCAM‐1 is vital to T cell recruitment and currently most research indicates that high doses are needed to improve tumor immunogenicity. However, we observed a more robust repopulation of both CD4 and CD8 T cells following 10Gy – a finding that might be due to a marked downregulation of ICAM‐1 following 2Gy doses that was not observed following 10Gy. An improved understanding of the endothelial adhesion receptor regulation depending on radiation fractionation is of therapeutic relevance: novel immune checkpoint inhibition strategies require efficient T cell recruitment to the tumor to be effective and so do, for instance, isolated and modified T cell (so called CAR‐T cell) therapies: Our results are the first to indicate that endothelial ligand regulation differs depending on radiation dose. Support or Funding Information DFG (HE 6810/3‐1 to J.M.H., HE 6897/2‐1 to G.H.S.) and the CMMC (CAP‐13 to J.M.H. and CAP‐16 to G.H.S. as well as B02 to G.H.S. and J.M.H.)

Cancer remains to be a leading cause of death worldwide, accounting for almost 10 million deaths in 2018. Radiation therapy (RT) is a common nonsurgical treatment in the management of patients with cancer that reduces disease recurrence and improves overall survival. However, preclinical RT modeling for accelerated bench‐to‐bedside transition of combination therapies is largely missing. While genetically engineered orthotopic murine tumor models can mimic human disease, conventional linear particle accelerator systems are not suited for targeted radiation of orthotopic tumors in mice. Although select institutions provide specialized mouse radiation systems overcoming these obstacles, most researchers are forced to use transplantable flank xenograft tumor models for targeted RT. We here report image‐guided, targeted radiation to mouse tumors using the Cyberknife (Accuray) radiation platform. The Cyberknife is a stereotactic radiosurgery system that utilizes real‐time image‐guidance to deliver high doses of radiation specifically to the tumor with minimal damage to the surrounding tissues using circular collimators as small as 5 mm. We applied targeted radiation of 2, 4, 6, and 8 Gy using field sizes of 7.5 to 12.5 mm to average gross tumor volumes (GTV) of volumes 0.87 cm3 (minimal 0.19 cm3) using Xsight (Accuray) spine‐based tumor localization. Treatment time lasted between 14 min (2 Gy), and 31 min (8 Gy), averaging at 20 min across all used doses. Doses were prescribed to 70% isodose, leading to a mean relative GTV dose of 92.1% (SD 1.6%), with a minimum dose of 80.3% (SD 3.8%). Coverage (volume of tumor that receive the prescription dose) was 99.4% (SD 0.8%) with a conformity (ratio of total tissue volume that receives the prescription isodose or more to tumor volume that receives the prescription isodose or more) of 1.10 (SD 0.03). To optimize the planning target volume (PTV), we examined 0, 1, 2, and 3 mm PTVs and analyzed the tumor tissue by immunohistochemistry staining of y‐H2AX. We found that 1 mm PTV is sufficient for target radiation of mouse tumors using the Cyberknife. Furthermore, we analyzed the impact of radiation on tumor infiltrating lymphocytes in a model of non‐small cell lung cancer (mutated for Kras and Trp35) by flow cytometry. We observed that higher radiation doses (6–8 Gy) decreased absolute cell numbers of lymphocytes and myeloid cells by approximately half compared to low doses (2–4 Gy) or non‐radiated. In summary, we here demonstrate that the Cyberknife system allows image‐guided targeted radiation of murine tumors with high precision and thus constitutes a novel promising platform for mouse radiation studies, and especially combination treatment studies. Support or Funding Information This study was supported by the DFG (HE 6810/3‐1 to J.M.H., HE 6897/2‐1 to G.H.S.) and the CMMC (CAP‐13 to J.M.H. and CAP‐16 to G.H.S. as well as B02 to G.H.S. and J.M.H.).