Induction of heme oxygenase‑1 expression protects articular chondrocytes against cilostazol‑induced cellular senescence

Spatially multicellular variability of intervertebral disc degeneration by comparative single-cell analysis

Previous studies have revealed cellular heterogeneity in intervertebral discs (IVDs). However, the cellular and molecular alteration patterns of cell populations during degenerative progression remain to be fully elucidated. To illustrate the cellular and molecular alteration of cell populations in intervertebral disc degeneration (IDD), we perform single cell RNA sequencing on cells from four anatomic sites of healthy and degenerative goat IVDs. EGLN3+ StressCs, TGFBR3+ HomCs and GPRC5A+ RegCs exhibit the characteristics associated with resistance to stress, maintaining homeostasis and repairing, respectively. The frequencies and signatures of these cell clusters fluctuate with IDD. Notably, the chondrogenic differentiation programme of PROCR+ progenitor cells is altered by IDD, while notochord cells turn to stemness exhaustion. In addition, we characterise CAV1+ endothelial cells that communicate with chondrocytes through multiple signalling pathways in degenerative IVDs. Our comprehensive analysis identifies the variability of key cell clusters and critical regulatory networks responding to IDD, which will facilitate in-depth investigation of therapeutic strategies for IDD.

Pharmacological Targeting of Heme Oxygenase-1 in Osteoarthritis

Osteoarthritis (OA) is a common aging-associated disease that clinically manifests as joint pain, mobility limitations, and compromised quality of life. Today, OA treatment is limited to pain management and joint arthroplasty at the later stages of disease progression. OA pathogenesis is predominantly mediated by oxidative damage to joint cartilage extracellular matrix and local cells such as chondrocytes, osteoclasts, osteoblasts, and synovial fibroblasts. Under normal conditions, cells prevent the accumulation of reactive oxygen species (ROS) under oxidatively stressful conditions through their adaptive cytoprotective mechanisms. Heme oxygenase-1 (HO-1) is an iron-dependent cytoprotective enzyme that functions as the inducible form of HO. HO-1 and its metabolites carbon monoxide and biliverdin contribute towards the maintenance of redox homeostasis. HO-1 expression is primarily regulated at the transcriptional level through transcriptional factor nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2), specificity protein 1 (Sp1), transcriptional repressor BTB-and-CNC homology 1 (Bach1), and epigenetic regulation. Several studies report that HO-1 expression can be regulated using various antioxidative factors and chemical compounds, suggesting therapeutic implications in OA pathogenesis as well as in the wider context of joint disease. Here, we review the protective role of HO-1 in OA with a focus on the regulatory mechanisms that mediate HO-1 activity.

CO ameliorates endothelial senescence induced by 5-fluorouracil through SIRT1 activation

Endothelial senescence is the main risk factor that contributes to vascular dysfunction and the progression of vascular disease. Carbon monoxide (CO) plays an important role in preventing vascular dysfunction and in maintaining vascular physiology or homeostasis. The application of exogenous CO has been shown to confer protection in several models of cardiovascular injury or disease, including hypertension, atherosclerosis, balloon-catheter injury, and graft rejection. However, the mechanism by which CO prevents endothelial senescence has been largely unexplored. The aim of this study was to evaluate the effects of CO on endothelial senescence and to investigate the possible mechanisms underlying this process. We measured the levels of senescence-associated-β-galactosidase activity, senescence-associated secretory phenotype, reactive oxygen species (ROS) production, and stress granule in human umbilical vein endothelial cells and the WI-38 human diploid fibroblast cell line. We found that 5-fluorouracil (5FU)-induced ROS generation was inhibited by CO-releasing molecules (CORM)-A1 treatment, and endothelial senescence induced by 5FU was attenuated by CORM-A1 treatment. The SIRT1 inhibitor EX527 reversed the inhibitory effect of CO on the 5FU-induced endothelial senescence. Furthermore, SIRT1 deficiency abolished the stress granule formation by CO. Our results suggest that CO alleviates the endothelial senescence induced by 5FU through SIRT1 activation and may hence have therapeutic potential for the treatment of vascular diseases.

Heme oxygenase-1 prevents heart against myocardial infarction by attenuating ischemic injury-induced cardiomyocytes senescence

Background

Cellular senescence is a stable cell-cycle arrest induced by telomere shortening and various types of cellular stress including oxidative stress, oncogene activation, DNA damage etc. Heme oxygenase-1 (HO-1) is an inducible stress-response protein that plays antioxidant and anti-apoptotic effects. However, the role and underlying mechanisms of HO-1 in cellular senescence in heart are largely unknown.

Methods

Echocardiography was employed to detect the effect of HO-1 on heart function in adult mice with myocardial infarction (MI) and aged mice. The senescence markers, p53, p16 and LaminB, were analyzed by western blot. The immunofluorescence and immunohistochemical staining were applied to analyze the expression level of p16. SA-β-Gal staining showed the level of cardiomyocyte senescence.

Findings

We found that hemin significantly induced the expression of HO-1, which notably suppressed cardiomyocyte senescence containing the secretion of senescence-associated secretory phenotype. Further studies showed that systemic HO-1 transgenic overexpression improved heart function by inhibiting aging-induced extracellular matrix deposition and fibrogenesis. More importantly, treatment of hemin improved heart function in MI mice. Furthermore, forced expression of HO-1 blunted cardiomyocyte senescence in natural aged mice and in primary cultured neonatal mouse cardiomyocytes.

Interpretation

Our study revealed that HO-1 improved heart function and attenuated cardiomyocyte senescence triggered by ischemic injury and aging. In addition, HO-1 induction alleviated H₂O₂-induced cardiomyocyte senescence. Finally, our study suggested a novel mechanism of HO-1 to play cardioprotective effect.

Fund

This study was supported by the National Natural Science Foundation of China (81770284 to Hongli Shan); and the National Natural Science Foundation of China (81673425, 81872863 to Yuhong Zhou). The National Natural Science Foundation of China (81473213 to Chaoqian Xu). National Key R&D Program of China (2017YFC1307403 to Baofeng Yang), National Natural Science Foundation of China (81730012 to Baofeng Yang).

Inhibition of protein kinase CK2 facilitates cellular senescence by inhibiting the expression of HO-1 in articular chondrocytes

Protein kinase casein kinase 2 (CK2) is important in the regulation of cell proliferation and death, even under pathological conditions. Previously, we reported that CK2 regulates the expression of heme oxygenase‑1 (HO‑1) in stress‑induced chondrocytes. In the present study, it was shown that CK2 is involved in the dedifferentiation and cellular senescence of chondrocytes. Treatment of primary articular chondrocytes with CK2 inhibitors, 4,5,6,7‑terabromo‑2‑azabenzimidazole (TBB) or 5,6‑dichlorobenzimidazole 1‑β‑D‑ribofuranoside (DRB), induced an increase in senescence‑associated β‑galactosidase (SA‑β‑gal) staining. In addition, TBB reduced the expression of type II collagen and stimulated the accumulation of β‑catenin, phenotypic markers of chondrocyte differentiation and dedifferentiation, respectively. It was also observed that the abrogation of CK2 activity by CK2 small interfering RNA induced phenotypes of chondrocyte senescence. The association between HO‑1 and cellular senescence was also examined in CK2 inhibitor‑treated chondrocytes. Pretreatment with 3‑morpholinosydnonimine hydrochloride, an inducer of the HO‑1 expression, or overexpression of the HO‑1 gene significantly delayed chondrocyte senescence. These results show that CK2 is associated with chondrocyte differentiation and cellular senescence and that this is due to regulation of the expression of HO‑1. Furthermore, the findings suggest that CK2 is crucial as an anti‑aging factor during chondrocyte senescence.

Role of the Inflammation-Autophagy-Senescence Integrative Network in Osteoarthritis

Osteoarthritis is the most common musculoskeletal disease causing chronic disability in adults. Studying cartilage aging, chondrocyte senescence, inflammation, and autophagy mechanisms have identified promising targets and pathways with clinical translatability potential. In this review, we highlight the most recent mechanistic and therapeutic preclinical models of aging with particular relevance in the context of articular cartilage and OA. Evidence supporting the role of metabolism, nuclear receptors and transcription factors, cell senescence, and circadian rhythms in the development of musculoskeletal system degeneration assure further translational efforts. This information might be useful not only to propose hypothesis and advanced models to study the molecular mechanisms underlying joint degeneration, but also to translate our knowledge into novel disease-modifying therapies for OA.

Chitosan Treatment Delays the Induction of Senescence in Human Foreskin Fibroblast Strains

Fibroblasts have been extensively used as a model to study cellular senescence. The purpose of this study was to investigate whether the human foreskin fibroblast aging process could be regulated by using the biomaterial chitosan. Fibroblasts cultured on commercial tissue culture polystyrene (TCPS) entered senescence after 55–60 population doublings (PDs), and were accompanied by larger cell shape, higher senescence-associated β-galactosidase (SA β-gal) activity, lower proliferation capacity, and upregulation of senescence-associated molecular markers p21, p53, retinoblastoma (pRB), and p16. Before senescence was reached, PD48 cells were collected from TCPS and seeded on chitosan for three days (PD48-Cd3) to form multicellular spheroids. The protein expression of senescence-associated secretory phenotypes (SASPs) and senescence-associated molecular markers of these cells in PD48-Cd3 spheroids were downregulated significantly. Following chitosan treatment, fibroblasts reseeded on TCPS showed lower SA β-gal activity, increased cellular motility, and a higher proliferation ability of 70–75 PDs. These phenotypic changes were not accompanied by colonies forming in soft agar and a continuous decrease in the senescence-associated proteins p53 and pRB which act as a barrier to tumorigenesis. These results demonstrate that chitosan treatment could delay the induction of senescence which may be useful and safe for future tissue engineering applications.