Project description:Targeting senescent cells for therapeutic purposes is gaining momentum across various organ systems. However, concerns about potential off-target effects have been raised. Previous studies have shown that removing senescent cells expressing high levels of p16 (p16high) can hinder processes like wound healing. Here, we identify a distinct senescent cell population during dermal wound healing characterized by high expression level of p21 (p21high) using the p21-Cre mouse model. Using a standard cutaneous injury model, we find that eliminating p21high cells can expedite wound closure, in contrast to the effects of removing p16high cells. Through Xenium, a single cell spatial imaging platform, we show that p21high cells are distinct from p16high cells, with p21high cells mainly comprising fibroblasts, immune cells, keratinocytes, and endothelial cells with a pro-inflammatory profile. Moreover, inhibition of NF-kB signaling specifically from p21high cells partially contributes to the accelerated wound healing rates. These findings highlight the heterogeneity of senescent cells during wound healing responses within the skin and likely in other conditions.
Project description:Targeting senescent cells for therapeutic purposes is gaining momentum across various organ systems. However, concerns about potential off-target effects have been raised. Previous studies have shown that removing senescent cells expressing high levels of p16 (p16high) can hinder processes like wound healing. Here, we identify a distinct senescent cell population during dermal wound healing characterized by high expression level of p21 (p21high) using the p21-Cre mouse model. Using a standard cutaneous injury model, we find that eliminating p21high cells can expedite wound closure, in contrast to the effects of removing p16high cells. Through Xenium, a single cell spatial imaging platform, we show that p21high cells are distinct from p16high cells, with p21high cells mainly comprising fibroblasts, immune cells, keratinocytes, and endothelial cells with a pro-inflammatory profile. Moreover, inhibition of NF-kB signaling specifically from p21high cells partially contributes to the accelerated wound healing rates. These findings highlight the heterogeneity of senescent cells during wound healing responses within the skin and likely in other conditions.
Project description:Cells expressing features of cellular senescence, including upregulation of p21 and p16, appear transiently following tissue injury, yet the properties of these cells or how they contrast with age-induced senescent cells remains unclear. Using skeletal fracture as a model of acute injury, we identified rapidly-appearing senescent-like cells, marked by p21 expression, that negatively affected fracture healing. p21+ callus cells, which consisted predominantly of neutrophils and osteochondroprogenitors, existed as transient cells specific to injury and expressed high levels of senescence-associated factors known to impair bone formation and induce paracrine senescence. Targeted genetic clearance of p21+ cells suppressed senescence-associated signatures within the fracture callus and accelerated fracture healing. By contrast, p21+ cell clearance did not alter bone loss due to aging; conversely, p16+ cell clearance, known to alleviate skeletal aging, did not affect fracture healing. Together, our findings establish contextual roles of senescent/senescent-like cells that may be leveraged for therapeutic opportunities.
Project description:Cellular senescence drives chronic sterile inflammation during aging via the senescence-associated secretory phenotype (SASP); however, the cell types responsible for this pathology remain poorly defined. Here, we identify p21⁺Trem2⁺ senescent macrophages as a major source of inflammaging. Using primary mouse and human macrophages, we developed a model of DNA damage and cholesterol-induced senescence and applied multi-omic profiling to fully characterize senescent macrophages. We found that senescent macrophages exhibit a distinctive p21-TREM2 expression profile and SASP, driven in part by type-I interferon signaling via secreted mitochondrial DNA. We also found that senescent macrophage accumulation occurs in aged and MASLD mouse livers and is enriched in human cirrhotic liver tissue. Finally, senolytic treatment targeting senescent macrophages reduced liver inflammation and steatosis in both aged and MASLD mice. Together, these findings establish macrophage senescence as a central driver of chronic inflammation in aging and metabolic liver disease, highlighting a promising, tractable therapeutic target.
Project description:Cellular senescence is a permanent state of cell cycle arrest that protects the organism from tumorigenesis and regulates tissue integrity upon damage and during tissue remodeling. However, accumulation of senescent cells in tissues during aging contributes to age-related pathologies. A deeper understanding of the mechanisms regulating the viability of senescent cells is therefore required. Here we show that the CDK inhibitor p21 (CDKN1A) maintains the viability of DNA damage-induced senescent cells.
Project description:Cellular senescence drives chronic sterile inflammation during aging via the senescence-associated secretory phenotype (SASP); however, the cell types responsible for this pathology remain poorly defined. Here, we identify p21⁺Trem2⁺ senescent macrophages as a major source of inflammaging. Using primary mouse and human macrophages, we developed a model of DNA damage and cholesterol-induced senescence and applied multi-omic profiling to fully characterize senescent macrophages. We found that senescent macrophages exhibit a distinctive p21-TREM2 expression profile and SASP, driven in part by type-I interferon signaling via secreted mitochondrial DNA. We also found that senescent macrophage accumulation occurs in aged and MASLD mouse livers and is enriched in human cirrhotic liver tissue. Finally, senolytic treatment targeting senescent macrophages reduced liver inflammation and steatosis in both aged and MASLD mice. Together, these findings establish macrophage senescence as a central driver of chronic inflammation in aging and metabolic liver disease, highlighting a promising, tractable therapeutic target.
Project description:Cellular senescence drives chronic sterile inflammation during aging via the senescence-associated secretory phenotype (SASP); however, the cell types responsible for this pathology remain poorly defined. Here, we identify p21⁺Trem2⁺ senescent macrophages as a major source of inflammaging. Using primary mouse and human macrophages, we developed a model of DNA damage and cholesterol-induced senescence and applied multi-omic profiling to fully characterize senescent macrophages. We found that senescent macrophages exhibit a distinctive p21-TREM2 expression profile and SASP, driven in part by type-I interferon signaling via secreted mitochondrial DNA. We also found that senescent macrophage accumulation occurs in aged and MASLD mouse livers and is enriched in human cirrhotic liver tissue. Finally, senolytic treatment targeting senescent macrophages reduced liver inflammation and steatosis in both aged and MASLD mice. Together, these findings establish macrophage senescence as a central driver of chronic inflammation in aging and metabolic liver disease, highlighting a promising, tractable therapeutic target.
Project description:Cellular senescence drives chronic sterile inflammation during aging via the senescence-associated secretory phenotype (SASP); however, the cell types responsible for this pathology remain poorly defined. Here, we identify p21⁺Trem2⁺ senescent macrophages as a major source of inflammaging. Using primary mouse and human macrophages, we developed a model of DNA damage and cholesterol-induced senescence and applied multi-omic profiling to fully characterize senescent macrophages. We found that senescent macrophages exhibit a distinctive p21-TREM2 expression profile and SASP, driven in part by type-I interferon signaling via secreted mitochondrial DNA. We also found that senescent macrophage accumulation occurs in aged and MASLD mouse livers and is enriched in human cirrhotic liver tissue. Finally, senolytic treatment targeting senescent macrophages reduced liver inflammation and steatosis in both aged and MASLD mice. Together, these findings establish macrophage senescence as a central driver of chronic inflammation in aging and metabolic liver disease, highlighting a promising, tractable therapeutic target.
Project description:Cellular senescence drives chronic sterile inflammation during aging via the senescence-associated secretory phenotype (SASP); however, the cell types responsible for this pathology remain poorly defined. Here, we identify p21⁺Trem2⁺ senescent macrophages as a major source of inflammaging. Using primary mouse and human macrophages, we developed a model of DNA damage and cholesterol-induced senescence and applied multi-omic profiling to fully characterize senescent macrophages. We found that senescent macrophages exhibit a distinctive p21-TREM2 expression profile and SASP, driven in part by type-I interferon signaling via secreted mitochondrial DNA. We also found that senescent macrophage accumulation occurs in aged and MASLD mouse livers and is enriched in human cirrhotic liver tissue. Finally, senolytic treatment targeting senescent macrophages reduced liver inflammation and steatosis in both aged and MASLD mice. Together, these findings establish macrophage senescence as a central driver of chronic inflammation in aging and metabolic liver disease, highlighting a promising, tractable therapeutic target.