Periodic Reporting for period 2 - ODE (Unknown functions of Osteocyte DEath)
Période du rapport: 2022-12-01 au 2024-05-31
Osteocytes, residing as long-lived cells within the bone matrix, play a pivotal role in orchestrating the regulation of mechanical loading-induced bone renewal at the systemic level. Despite their significance, the mechanisms underlying osteocyte death and its impact on local bone homeostasis remain largely unexplored. Notably, enhanced osteocyte death has been implicated in various local bone diseases, including fractures, osteonecrosis, and arthritis, often accompanied by heightened local bone resorption.
In my prior research, I have provided evidence suggesting that when osteocytes undergo cell death, they experience secondary necrosis, primarily due to their secluded localization within the bone and the absence of phagocytic cells in the immediate vicinity. This phenomenon results in the release of substantial amounts of damage-associated molecular patterns (DAMPs) into the bone microenvironment. The proposed research, ODE (Osteocyte Death Exploration), aims to comprehensively characterize osteocyte death, elucidate the nature of the released DAMPs, and uncover the intricate molecular links between osteocyte death and the stimulation of osteoclasts. This investigation is particularly pertinent in the context of local bone diseases such as fractures, osteonecrosis, and arthritis.
The primary objective of ODE is to unravel the intricacies of osteocyte death, shedding light on the molecular mechanisms that govern this process. By understanding the nature of DAMPs released during osteocyte death, we aim to decipher their impact on the local bone microenvironment. The proposed research will delve into the molecular pathways that connect osteocyte death to the stimulation of osteoclasts, providing crucial insights into the mechanisms driving enhanced bone resorption in the context of various local bone diseases.
Moreover, ODE holds the promise of offering translational benefits by providing a deeper understanding of local bone homeostasis. The research outcomes are expected to contribute significantly to our knowledge of the molecular regulation of osteocyte death and its implications for the altered bone microenvironment observed in diseases like fractures, osteonecrosis, and arthritis. Ultimately, the findings from this proposal have the potential to inform future therapeutic strategies aimed at mitigating the detrimental effects of enhanced osteocyte death on bone health, offering novel avenues for clinical intervention and improved patient outcomes.
In my prior research, I have provided evidence suggesting that when osteocytes undergo cell death, they experience secondary necrosis, primarily due to their secluded localization within the bone and the absence of phagocytic cells in the immediate vicinity. This phenomenon results in the release of substantial amounts of damage-associated molecular patterns (DAMPs) into the bone microenvironment. The proposed research, ODE (Osteocyte Death Exploration), aims to comprehensively characterize osteocyte death, elucidate the nature of the released DAMPs, and uncover the intricate molecular links between osteocyte death and the stimulation of osteoclasts. This investigation is particularly pertinent in the context of local bone diseases such as fractures, osteonecrosis, and arthritis.
The primary objective of ODE is to unravel the intricacies of osteocyte death, shedding light on the molecular mechanisms that govern this process. By understanding the nature of DAMPs released during osteocyte death, we aim to decipher their impact on the local bone microenvironment. The proposed research will delve into the molecular pathways that connect osteocyte death to the stimulation of osteoclasts, providing crucial insights into the mechanisms driving enhanced bone resorption in the context of various local bone diseases.
Moreover, ODE holds the promise of offering translational benefits by providing a deeper understanding of local bone homeostasis. The research outcomes are expected to contribute significantly to our knowledge of the molecular regulation of osteocyte death and its implications for the altered bone microenvironment observed in diseases like fractures, osteonecrosis, and arthritis. Ultimately, the findings from this proposal have the potential to inform future therapeutic strategies aimed at mitigating the detrimental effects of enhanced osteocyte death on bone health, offering novel avenues for clinical intervention and improved patient outcomes.
Our research team has made an exciting breakthrough in understanding how bone cells, called osteocytes, respond to different challenges. Think of osteocytes as the guardians of our bones—they regulate the process of bone renewal triggered by physical activity. We wanted to explore how these cells react under various stressful situations like lack of nutrients, low oxygen levels, and inflammation.
Using advanced techniques like RNA sequencing and other lab tools, we uncovered specific pathways that lead to the death of osteocytes, with a focus on a process called ferroptosis. When osteocytes experienced a lack of nutrients, they followed a unique pathway that eventually led to a type of cell death. On the other hand, how well osteocytes survived depended on the level of oxygen available. At higher oxygen levels, they adapted and activated a survival pathway, while at lower levels, they succumbed to ferroptosis—a process linked to the accumulation of harmful molecules called reactive oxygen species (ROS).
Recognizing that we didn't know much about ferroptosis in osteocytes, we created cell lines where we turned off specific elements related to this process. This allowed us to understand how these elements played a crucial role in the ferroptosis pathway.
We also looked into another pathway called necrosis, which is a secondary event in osteocyte cell death. For a more real-world perspective, we used mice engineered to lack a specific element related to cell death in osteocytes. These mice underwent experiments mimicking arthritis, and we're studying how inflammation, bone structure, and osteocyte survival are affected.
Additionally, we are exploring the role of low oxygen levels in osteocyte cell death by using mice with a specific gene turned off in their osteocytes. This gene is involved in how cells respond to low oxygen, and by turning it off, we can understand its impact on osteocyte survival.
Our research also touched on a molecule called Dectin-1, which seems to be important in the formation of bone-eating cells called osteoclasts. We observed that when cells lacked Dectin-1, they had trouble becoming osteoclasts, and this finding was confirmed in mice with denser bones. Figuring out how Dectin-1 influences osteoclast formation is a key focus of our ongoing research.
Our studies involve both male and female mice exposed to models of arthritis and osteoporosis, and we're currently analyzing a large number of samples. By exploring these various aspects of osteocyte biology and cell death, we aim to deepen our understanding of bone health and diseases related to bones. Ultimately, this knowledge could contribute to advancements in treatments and care for skeletal issues.
Using advanced techniques like RNA sequencing and other lab tools, we uncovered specific pathways that lead to the death of osteocytes, with a focus on a process called ferroptosis. When osteocytes experienced a lack of nutrients, they followed a unique pathway that eventually led to a type of cell death. On the other hand, how well osteocytes survived depended on the level of oxygen available. At higher oxygen levels, they adapted and activated a survival pathway, while at lower levels, they succumbed to ferroptosis—a process linked to the accumulation of harmful molecules called reactive oxygen species (ROS).
Recognizing that we didn't know much about ferroptosis in osteocytes, we created cell lines where we turned off specific elements related to this process. This allowed us to understand how these elements played a crucial role in the ferroptosis pathway.
We also looked into another pathway called necrosis, which is a secondary event in osteocyte cell death. For a more real-world perspective, we used mice engineered to lack a specific element related to cell death in osteocytes. These mice underwent experiments mimicking arthritis, and we're studying how inflammation, bone structure, and osteocyte survival are affected.
Additionally, we are exploring the role of low oxygen levels in osteocyte cell death by using mice with a specific gene turned off in their osteocytes. This gene is involved in how cells respond to low oxygen, and by turning it off, we can understand its impact on osteocyte survival.
Our research also touched on a molecule called Dectin-1, which seems to be important in the formation of bone-eating cells called osteoclasts. We observed that when cells lacked Dectin-1, they had trouble becoming osteoclasts, and this finding was confirmed in mice with denser bones. Figuring out how Dectin-1 influences osteoclast formation is a key focus of our ongoing research.
Our studies involve both male and female mice exposed to models of arthritis and osteoporosis, and we're currently analyzing a large number of samples. By exploring these various aspects of osteocyte biology and cell death, we aim to deepen our understanding of bone health and diseases related to bones. Ultimately, this knowledge could contribute to advancements in treatments and care for skeletal issues.
The study explores how bones are regulated locally and how the breakdown of bone tissue (bone resorption) occurs. Specifically, it investigates the process of osteocytes (cells in bone tissue) dying and releasing certain signals (alarmins) that trigger bone resorption. The detailed process of osteocyte death in diseases affecting bones, and the involvement of certain receptors (CLRs) in connecting osteocyte death to bone resorption, is not fully understood.
The researcher's proposal aims to understand how osteocytes die in conditions like fractures, osteonecrosis, and arthritis, using both human and mouse models. The goal is to determine if blocking the pathway leading to osteocyte death has an impact on the progression of these diseases.
The study also focuses on the role of certain molecules (DAMPs) released by dead osteocytes in regulating the formation of osteoclasts, cells responsible for breaking down bone tissue. The idea is that these molecules activate specific receptors (CLRs) in osteoclasts, influencing their development. By identifying and manipulating these receptors, the researcher hopes to control osteoclast activity.
As a milestone we want to delineate osteocyte death during bone diseases, by studying osteocyte death in samples from patients with fractures, osteonecrosis, and arthritis, as well as characterizing osteocyte death in mouse models of these conditions.
Our next goal is to explore how blocking the pathway leading to osteocyte death affects the repair processes in fractures, as well as the progression of osteonecrosis and arthritis in mouse models.
the second milestone if to analyse molecules released from dead osteocytes and CLRs expression: This aim focuses on quantifying the release of DAMPs, molecules released by dead osteocytes, in controlled environments. Moreover, we measure the presence of identified DAMPs released during osteocyte death in live conditions, and their impact on osteoclastogenesis and in vivo bone remodelling
Our las milestone is to delineate the importance of CLRs for bone remodeling after osteocyte death: This aim seeks to investigate the effects of depleting CLRs, both genetically and pharmacologically, on bone changes following osteocyte death. The goal is to explore how blocking CLRs influences the repair processes in fractures, as well as the progression of osteonecrosis and arthritis in mouse models.
In summary, the project aims to uncover the unknown functions of osteocytes in various disease models and understand their connection to the formation of osteoclasts. Ultimately, the researcher wants to explore whether targeting these receptors, either through genetic methods or with drugs, can help maintain bone structure and prevent excessive bone loss caused by osteocyte death.
The researcher's proposal aims to understand how osteocytes die in conditions like fractures, osteonecrosis, and arthritis, using both human and mouse models. The goal is to determine if blocking the pathway leading to osteocyte death has an impact on the progression of these diseases.
The study also focuses on the role of certain molecules (DAMPs) released by dead osteocytes in regulating the formation of osteoclasts, cells responsible for breaking down bone tissue. The idea is that these molecules activate specific receptors (CLRs) in osteoclasts, influencing their development. By identifying and manipulating these receptors, the researcher hopes to control osteoclast activity.
As a milestone we want to delineate osteocyte death during bone diseases, by studying osteocyte death in samples from patients with fractures, osteonecrosis, and arthritis, as well as characterizing osteocyte death in mouse models of these conditions.
Our next goal is to explore how blocking the pathway leading to osteocyte death affects the repair processes in fractures, as well as the progression of osteonecrosis and arthritis in mouse models.
the second milestone if to analyse molecules released from dead osteocytes and CLRs expression: This aim focuses on quantifying the release of DAMPs, molecules released by dead osteocytes, in controlled environments. Moreover, we measure the presence of identified DAMPs released during osteocyte death in live conditions, and their impact on osteoclastogenesis and in vivo bone remodelling
Our las milestone is to delineate the importance of CLRs for bone remodeling after osteocyte death: This aim seeks to investigate the effects of depleting CLRs, both genetically and pharmacologically, on bone changes following osteocyte death. The goal is to explore how blocking CLRs influences the repair processes in fractures, as well as the progression of osteonecrosis and arthritis in mouse models.
In summary, the project aims to uncover the unknown functions of osteocytes in various disease models and understand their connection to the formation of osteoclasts. Ultimately, the researcher wants to explore whether targeting these receptors, either through genetic methods or with drugs, can help maintain bone structure and prevent excessive bone loss caused by osteocyte death.