The Potential Role and Therapeutic Relevance of Cellular Senescence in Skeletal Pathophysiology.

Biological aging profoundly impairs the homeostasis of the skeletal system. Cellular senescence, a hallmark of biological aging, plays an instrumental role in bone disease. The underlying mechanisms of cellular senescence, triggered by both intracellular and extracellular stimuli, are multifaceted and yet to be uncovered. Recent research indicates that acute cellular senescence often serves beneficial roles, such as contributing to growth, development, and tissue regeneration. By contrast, chronic cellular senescence, primarily driven by the accumulation of senescent cells (SnCs) and the release of senescence-associated secretory phenotypes (SASP), has detrimental effects on the skeletal system by irreversibly disrupting bone homeostasis and promoting age-related disorders. Furthermore, the bone marrow is rich in immune cells and their exposure to SASP often leads to immune dysfunction, resulting in unresolved chronic inflammation and compromised adaptive immunity. Until now, the impact of SnCs and SASP on the skeleton has remained elusive. Meanwhile, extensive efforts are being made to combat age-related diseases through various strategies. Among them, SnCs and SASP are the primary targets for antiaging therapeutic clearance, resulting in the development of "senolytics" and "senomorphics," respectively. In this review, we summarize and highlight the role of SnCs and SASP in skeletal pathophysiology, the mechanism of cellular senescence in affecting bone metabolism, and potential therapeutic approaches, particularly senolytics and senomorphics, in treating cellular senescence-related bone diseases.

Emerging roles of nerve-bone axis in modulating skeletal system.

Over the past decades, emerging evidence in the literature has demonstrated that the innervation of bone is a crucial modulator for skeletal physiology and pathophysiology. The nerve-bone axis sparked extensive preclinical and clinical investigations aimed at elucidating the contribution of nerve-bone crosstalks to skeleton metabolism, homeostasis, and injury repair through the perspective of skeletal neurobiology. To date, peripheral nerves have been widely reported to mediate bone growth and development and fracture healing via the secretion of neurotransmitters, neuropeptides, axon guidance factors, and neurotrophins. Relevant studies have further identified several critical neural pathways that stimulate profound alterations in bone cell biology, revealing a complex interplay between the skeleton and nerve systems. In addition, inspired by nerve-bone crosstalk, novel drug delivery systems and bioactive materials have been developed to emulate and facilitate the process of natural bone repair through neuromodulation, eventually boosting osteogenesis for ideal skeletal tissue regeneration. Overall, this work aims to review the novel research findings that contribute to deepening the current understanding of the nerve-bone axis, bringing forth some schemas that can be translated into the clinical scenario to highlight the critical roles of neuromodulation in the skeletal system.

CLSPN actives Wnt/ß-catenin signaling to facilitate glycolysis and cell proliferation in oral squamous cell carcinoma.

OBJECTIVE: Oral squamous cell carcinoma (OSCC) is a common malignancy with a poor prognosis. This study aimed to determine the influence and underlying mechanisms of CLSPN on OSCC. METHODS: CLSPN expression was tested using quantitative real-time polymerase chain reaction, immunohistochemistry, and western blotting. Flow cytometry, cell counting kit, and colony formation assays were performed to determine OSCC cell apoptosis, viability, and proliferation, respectively. In OSCC cells, the extracellular acidification rate (ECAR), oxygen consumption rate (OCR), glucose uptake, and lactate production were determined using the corresponding kits. Changes in the protein levels of HK2, PKM2, LDHA, Wnt3a, and ß-catenin were assessed using western blotting. RESULTS: CLSPN expression was increased in OSCC tissues. Overexpression of CLSPN in HSC-2 cells promoted cell proliferation, increased the levels of ECAR, glucose uptake, and lactate production, and increased the protein levels of HK2, PKM2, LDHA, Wnt3a, and ß-catenin, but inhibited OCR levels and apoptosis. The knockdown of CLSPN in CAL27 cells resulted in the opposite results. Moreover, the effects of CLSPN overexpression on glycolysis and OSCC cell proliferation were reversed by Wnt3a knockdown. In vivo, knockdown of CLSPN restrained tumor growth, glycolysis, and the activation of Wnt/ß-catenin signaling. CONCLUSION: CLSPN promoted glycolysis and OSCC cell proliferation, and reduced apoptosis, which was achieved by the activation of Wnt/ß-catenin signaling pathway.

Mogroside V Improves Follicular Development and Ovulation in Young-Adult PCOS Rats Induced by Letrozole and High-Fat Diet Through Promoting Glycolysis.

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. In this study, we induced a young-adult PCOS rat model by oral administration of letrozole combined with a high-fat diet and then treated with mogroside V (MV) to evaluate the protective effects of MV on endocrine and follicle development in young-adult PCOS rats. MV (600 mg/kg/day) administration not only significantly reduced the body weight and ovary weight, but also attenuated the disrupted estrous cycle and decreased the level of testosterone. MV restored the follicular development, especially by increasing the number of corpus luteum and the thickness of the granular layer in young-adult POCS rats. Moreover, metabolomics showed that MV markedly increased the levels of D-Glucose 6-phosphate, lactate and GTP, while decreased the level of pyruvate. Bioinformatic analysis revealed that MV recovered multiple metabolism-related processes including gluconeogenesis, glycolysis and glucose metabolic process. Further real-time quantitative PCR analysis showed that MV upregulated the expression of lactate dehydrogenase A (Ldha), hexokinase 2 (Hk2) and pyruvate kinase M2 (Pkm2). Western blotting and immunohistochemistry analysis showed that MV restored the expression of lactate dehydrogenase A (Ldha), hexokinase 2 (Hk2) and pyruvate kinase M2 (Pkm2). Collectively, these findings indicated that MV could effectively improve the ovarian microenvironment by upregulating the expression of LDHA, HK2 and PKM2 in granulosa cells and enhancing lactate and energy production, which may contribute to follicle development and ovulation of young-adult PCOS rats.

Resveratrol Improves Follicular Development of PCOS Rats by Regulating the Glycolytic Pathway.

SCOPE: Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder that can cause infertility; however, the underlying mechanisms remain ill-defined, and there are no available drugs or strategies for the treatment of PCOS. This study examined the therapeutic effect of resveratrol in a rat model of PCOS. METHODS AND RESULTS: PCOS is induced in rats by administration of letrozole and a high fat diet to determine whether resveratrol has a protective effect. Oral administration of resveratrol significantly decreased body weight, as well as the serum levels of testosterone and follicle stimulating hormone. Resveratrol improved the estrous cycle by restoring the thickness and number of granular cells. Resveratrol increased the levels of lactate and ATP, decreased pyruvate levels, and restored the glycolytic process, upregulating LDHA, HK2, and PKM2. Resveratrol also upregulated SIRT2, thereby modulating the expression of rate-limiting enzymes of glycolysis. CONCLUSION: Resveratrol suppressed damage to the ovaries in PCOS rats by restoring glycolytic activity, providing potential targets for the treatment of PCOS.

Serum amyloid A in polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS), i.e., anovulation, hyperandrogenemia and polycystic ovary, is an endocrine-metabolic disease affecting reproductive aged women. Women with PCOS are likely to develop obesity, dyslipidemia, type 2 diabetes mellitus (T2DM) and cardiovascular diseases at a younger age. Despite high frequency and severe disease burden, the pathophysiological mechanisms of PCOS remain poorly defined and correspondingly have no therapeutic options. Emerging evidence has demonstrated that PCOS is accompanied with low-grade chronic inflammation and biomarkers thereof. Interestingly, serum amyloid A (SAA) has recently been identified as a potential marker of infection and inflammation and a number of studies have reported an association with PCOS. In this review, we explore the relationship between SAA and hyperandrogenemia, inflammation, obesity and insulin resistance, and provide convincing evidence for SAA as a potential inflammatory biomarker in PCOS.