A new mouse model of radiation-induced liver disease reveals mitochondrial dysfunction as an underlying fibrotic stimulus

Cell death and iron deposition in the liver in two murine models of acute radiation syndrome

Different tissues exhibit differential sensitivity to ionizing radiation exposure and display different time courses of pathologies that are not well understood. Ionizing radiation causes hemolysis of red blood cells, causing the release of iron that is taken up by a variety of tissues. The increased iron has been associated with altered expression of iron binding proteins and, in some cases, markers of ferroptosis. Here we examined the time course of iron uptake in murine liver following 60Co total body irradiation (TBI) at 7.9 Gy (LD90/30) and 6.85 Gy (LD0/30). 7.9 Gy induced hydropic degeneration, micro-vesicular steatosis, and inflammatory cell infiltration, whereas at 6.85 Gy the livers displayed only inflammatory cell infiltration. In both cases, iron levels increased significantly, maximal at ~21 days post-TBI. Increased iron was associated with altered expression of ferritin, heme oxygenase, an enzyme required for iron recycling, and the pro-inflammatory cytokine serum amyloid A, maximal ~16-21 days. 7.9 Gy induced liver caspase-3 activation consistent with apoptosis. In contrast, 6.85 Gy induced markers of ferroptosis but not of apoptosis. Our data indicate that iron is deposited in the liver at a delayed time point following radiation and is associated with increased ferritin, HO-1, and inflammatory cytokine production.

Liver quad culture chip as a model for radiation injury research

Both cancer patients receiving radiotherapy and civilians in a mass casualty nuclear event may suffer from radiation induced damage to organ systems. Radiation induced liver disease (RILD) can cause acute and long-term organ dysfunction that potentially leads to death. The objective of this study was to ascertain the validity of a liver quad-culture chip, a micro-physiological system comprising primary human hepatocytes and non-parenchymal cells (NPCs), including liver sinusoidal endothelial cells, hepatic stellate cells (HSCs), and Kupffer cells, as a model for RILD. The radiation exposure to the chip model resulted in DNA damage and cellular senescence of hepatocytes and NPCs. We observed metabolic dysfunction, inflammation, endothelial dysfunction, and HSCs activation. Whole genome sequencing revealed gene alterations in pathways relevant to RILD, as well as the potential efficacy of N-acetylcysteine amide (NACA) against RILD. NACA exhibited the capacity to mitigate DNA damage and cellular senescence and decreased the impact of radiation exposure on other pathophysiological changes. CDKN1A and miR-34a-5p were validated as useful radiation response and treatment efficacy biomarkers. These findings highlight the potential of the liver quad-culture chip as an effective model for investigating the microenvironment in RILD and for evaluating the efficacy of therapeutic countermeasures and biomarkers.

Liver injury in sepsis: manifestations, mechanisms and emerging therapeutic strategies

Sepsis is defined as a condition related to infection that manifests with multiorgan dysfunction, representing a life-threatening state. Consequently, severe complications frequently occur, with liver injury being one of the most prevalent serious complications of sepsis. Liver dysfunction during sepsis serves as an independent predictor of mortality. This review provides a comprehensive overview of current research on sepsis-induced liver injury (SILI), encompassing the clinical manifestations, diagnostic criteria, pathogenesis and therapeutic strategies associated with this condition. SILI may manifest as hypoxic hepatitis due to ischemia and shock, cholestasis resulting from abnormal bile metabolism, or bile duct sclerosis. The pathophysiology of sepsis involves intricate interactions among the inflammatory response, oxidative stress, and cell death. All of these factors complicate treatment and represent potential targets for therapeutic intervention. Furthermore, this review addresses the limitations inherent in conventional therapies currently employed for managing SILI and emphasizes the potential of novel targeted strategies aimed at addressing the fundamental mechanisms underlying this condition.

Radiation induced liver injury (RILI) evaluation using longitudinal computed tomography (CT) in image-guided precision murine radiotherapy

Purpose

We aim to perform image-guided, dose-escalated, well-controlled liver-irradiated animal studies and subsequently evaluate radiation induced liver injury (RILI) using longitudinal CT.

Methods

Eighteen 6-8 weeks mice were divided into three groups: control, 15Gy and 30Gy irradiated groups. The animal protocol was approved by the animal care ethics committee of our institution. Precision radiotherapy started with CT simulation, followed by treatment planning using volumetric modulated arc therapy (VMAT), image guidance with cone beam CT (CBCT) and radiation delivery on a medical linear accelerator. Weekly CT was conducted on the same CT simulator using same scanning parameters. At the end of fifth week, all mice were sacrificed, and histological staining was performed. Body weight, liver volume, HU values and histogram distributions were analyzed.

Results

Body weight of irradiation groups was significantly reduced compared to that of the control group (p<0.05). Liver volume in irradiated groups was reduced too. The average liver HU was significantly reduced in irradiated groups (HU mean = 62±3, 48±6, and 36±8 for the control, 15Gy and 30Gy respectively; p control vs. 15Gy < 0.05, p control vs. 30Gy < 0.05). A linear relationship between liver HU and radiation dose was found. Furthermore, HU histogram changes with time and dose showed not only density but also structure might be affected by radiation. HE and Masson Trichrome staining confirmed histological change and increased collagen deposition in irradiated liver.

Conclusion

Longitudinal unenhanced CT is a useful imaging tool to evaluate the severity and progression of radiation induced liver injury.

Current Insights into Molecular Mechanisms and Potential Biomarkers for Treating Radiation-Induced Liver Damage

Highly conformal delivery of radiation therapy (RT) has revolutionized the treatment landscape for primary and metastatic liver cancers, yet concerns persist regarding radiation-induced liver disease (RILD). Despite advancements, RILD remains a major dose-limiting factor due to the potential damage to normal liver tissues by therapeutic radiation. The toxicity to normal liver tissues is associated with a multitude of physiological and pathological consequences. RILD unfolds as multifaceted processes, intricately linking various responses, such as DNA damage, oxidative stress, inflammation, cellular senescence, fibrosis, and immune reactions, through multiple signaling pathways. The DNA damage caused by ionizing radiation (IR) is a major contributor to the pathogenesis of RILD. Moreover, current treatment options for RILD are limited, with no established biomarker for early detection. RILD diagnosis often occurs at advanced stages, highlighting the critical need for early biomarkers to adjust treatment strategies and prevent liver failure. This review provides an outline of the diverse molecular and cellular mechanisms responsible for the development of RILD and points out all of the available biomarkers for early detection with the aim of helping clinicians decide on advance treatment strategies from a single literature recourse.

Late Effects of Ionizing Radiation on the Ultrastructure of Hepatocytes and Activity of Lysosomal Enzymes in Mouse Liver Irradiated In Vivo

The study aimed to investigate late radiation-induced changes in the histology, ultrastructure, and activity of lysosomal enzymes in mouse liver exposed to ionizing radiation. The experiment was conducted on C57BL/6J male mice whose distal part of the liver was exposed occasionally to single doses of radiation (6 MV photons) during targeted heart irradiation; estimated doses delivered to analyzed tissue were 0.025 Gy, 0.25 Gy, 1 Gy, and 2 Gy. Tissues were collected 40 weeks after irradiation. We have observed that late effects of radiation have an adaptive nature and their intensity was dose-dependent. Morphological changes in hepatocytes included an increased number of primary lysosomes and autophagic vacuoles, which were visible in tissues irradiated with 0.25 Gy and higher doses. On the other hand, a significant increase in the activity of lysosomal hydrolases was observed only in tissues exposed to 2 Gy. The etiology of these changes may be multifactorial and result, among others, from unintentional irradiation of the distal part of the liver and/or functional interaction of the liver with an irradiated heart. In conclusion, we confirmed the presence of late dose-dependent ultrastructural and biochemical changes in mouse hepatocytes after liver irradiation in vivo.

Radiation injury and gut microbiota-based treatment

The exposure to either medical sources or accidental radiation can cause varying degrees of radiation injury (RI). RI is a common disease involving multiple human body parts and organs, yet effective treatments are currently limited. Accumulating evidence suggests gut microbiota are closely associated with the development and prevention of various RI. This article summarizes 10 common types of RI and their possible mechanisms. It also highlights the changes and potential microbiota-based treatments for RI, including probiotics, metabolites, and microbiota transplantation. Additionally, a 5P-Framework is proposed to provide a comprehensive strategy for managing RI.

Multiplexed Imaging Mass Cytometry Analysis in Preclinical Models of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. PDAC is characterized by a complex tumor microenvironment (TME), that plays a pivotal role in disease progression and resistance to therapy. Investigating the spatial distribution and interaction of TME cells with the tumor is the basis for understanding the mechanisms underlying disease progression and represents a current challenge in PDAC research. Imaging mass cytometry (IMC) is the major multiplex imaging technology for the spatial analysis of tumor heterogeneity. However, there is a dearth of reports of multiplexed IMC panels for different preclinical mouse models, including pancreatic cancer. We addressed this gap by utilizing two preclinical models of PDAC: the genetically engineered, bearing KRAS-TP53 mutations in pancreatic cells, and the orthotopic, and developed a 28-marker panel for single-cell IMC analysis to assess the abundance, distribution and phenotypes of cells involved in PDAC progression and their reciprocal functional interactions. Herein, we provide an unprecedented definition of the distribution of TME cells in PDAC and compare the diversity between transplanted and genetic disease models. The results obtained represent an important and customizable tool for unraveling the complexities of PDAC and deciphering the mechanisms behind therapy resistance.

Tissue fibrosis induced by radiotherapy: current understanding of the molecular mechanisms, diagnosis and therapeutic advances

Cancer remains the leading cause of death around the world. In cancer treatment, over 50% of cancer patients receive radiotherapy alone or in multimodal combinations with other therapies. One of the adverse consequences after radiation exposure is the occurrence of radiation-induced tissue fibrosis (RIF), which is characterized by the abnormal activation of myofibroblasts and the excessive accumulation of extracellular matrix. This phenotype can manifest in multiple organs, such as lung, skin, liver and kidney. In-depth studies on the mechanisms of radiation-induced fibrosis have shown that a variety of extracellular signals such as immune cells and abnormal release of cytokines, and intracellular signals such as cGAS/STING, oxidative stress response, metabolic reprogramming and proteasome pathway activation are involved in the activation of myofibroblasts. Tissue fibrosis is extremely harmful to patients' health and requires early diagnosis. In addition to traditional serum markers, histologic and imaging tests, the diagnostic potential of nuclear medicine techniques is emerging. Anti-inflammatory and antioxidant therapies are the traditional treatments for radiation-induced fibrosis. Recently, some promising therapeutic strategies have emerged, such as stem cell therapy and targeted therapies. However, incomplete knowledge of the mechanisms hinders the treatment of this disease. Here, we also highlight the potential mechanistic, diagnostic and therapeutic directions of radiation-induced fibrosis.

Cellular stress in the pathogenesis of nonalcoholic steatohepatitis and liver fibrosis

The burden of chronic liver disease is rising substantially worldwide. Fibrosis, characterized by excessive deposition of extracellular matrix proteins, is the common pathway leading to cirrhosis, and limited treatment options are available. There is increasing evidence suggesting the role of cellular stress responses contributing to fibrogenesis. This Review provides an overview of studies that analyse the role of cellular stress in different cell types involved in fibrogenesis, including hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells and macrophages.

A 31-plex panel for high-dimensional single-cell analysis of murine preclinical models of solid tumors by imaging mass cytometry

Currently, the study of resistance mechanisms and disease progression in cancer relies on the capacity to analyze tumors as a complex ecosystem of healthy and malignant cells. Therefore, one of the current challenges is to decipher the intra-tumor heterogeneity and especially the spatial distribution and interactions of the different cellular actors within the tumor. Preclinical mouse models are widely used to extend our understanding of the tumor microenvironment (TME). Such models are becoming more sophisticated and allow investigating questions that cannot be addressed in clinical studies. Indeed, besides studying the tumor cell interactions within their environment, mouse models allow evaluating the efficacy of new drugs and delivery approaches, treatment posology, and toxicity. Spatially resolved analyses of the intra-tumor heterogeneity require global approaches to identify and localize a large number of different cell types. For this purpose, imaging mass cytometry (IMC) is a major asset in the field of human immuno-oncology. However, the paucity of validated IMC panels to study TME in pre-clinical mouse models remains a critical obstacle to translational or basic research in oncology. Here, we validated a panel of 31 markers for studying at the single-cell level the TME and the immune landscape for discovering/characterizing cells with complex phenotypes and the interactions shaping the tumor ecosystem in mouse models.

Single-cell high-dimensional imaging mass cytometry: one step beyond in oncology

Solid tumors have a dynamic ecosystem in which malignant and non-malignant (endothelial, stromal, and immune) cell types constantly interact. Importantly, the abundance, localization, and functional orientation of each cell component within the tumor microenvironment vary significantly over time and in response to treatment. Such intratumoral heterogeneity influences the tumor course and its sensitivity to treatments. Recently, high-dimensional imaging mass cytometry (IMC) has been developed to explore the tumor ecosystem at the single-cell level. In the last years, several studies demonstrated that IMC is a powerful tool to decipher the tumor complexity. In this review, we summarize the potential of this technology and how it may be useful for cancer research (from preclinical to clinical studies).