Osam Mazda

Articular cartilage exists under hypoxic conditions, where hypoxia-inducible factor (HIF)-1α plays a critical role in maintaining its homeostasis. In osteoarthritis (OA), however, this hypoxic environment is disrupted, and decreased HIF-1α expression contributes to disease progression. HIF-prolyl hydroxylase (HIF-PH) inhibitors stabilize HIF-1α and are clinically used to treat renal anemia; therefore, they may also exert therapeutic effects in OA through the same mechanism. However, their effects on articular cartilage remain unclear. In this study, we investigated the effects of Roxadustat, a HIF-PH inhibitor, both in vitro using rat chondrocytes and in vivo using a monosodium iodoacetate (MIA)-induced rat OA model. Roxadustat showed no cytotoxicity and significantly increased the protein expression of HIF-1α, SRY-box transcription factor 9 (SOX9), and Aggrecan in monolayer cultures. In three-dimensional spheroid cultures, Roxadustat enhanced Safranin O staining and extracellular matrix production and significantly upregulated SOX9 and ACAN mRNA expression. Furthermore, intra-articular administration of Roxadustat in the MIA-induced OA model suppressed cartilage degeneration and significantly reduced the Modified Mankin score. These findings demonstrate that Roxadustat promotes anabolic responses in chondrocytes through stabilization of HIF-1α and suppresses cartilage degeneration in OA. Intra-articular administration of HIF-PH inhibitors may represent a novel disease-modifying therapeutic strategy for OA.

Naked mole-rats are extremely long-lived rodents with a lifespan of up to 40 years, during which cellular and tissue aging is rarely observed. In this study, we analyzed the extracellular matrix (ECM) of naked mole-rat skin at the molecular level to elucidate the molecules involved in anti-aging and their localization. Raman spectroscopy and Fourier transform infrared spectroscopy were applied to investigate the hierarchical structure of the ECM, showing that, whereas the epidermis of aged mice had thinned, the epidermis of naked mole-rats became thickened and hyaluronic acid (HA) was distributed under the basement membrane. Furthermore, naked mole-rat skin had a regular skin texture and flexibility, allowing the maintenance of a youthful appearance. Hyaluronic acid in naked mole-rats characteristically exists as clusters (chain HA) in skin tissue, where it is thought to permit moisture retention and maintain elasticity, contributing to the skin’s youthful appearance. These results suggested that not only the density of ECM but also its spatial distribution and topographic properties are important for skin anti-aging. Our findings may contribute to the elucidation of skin disease pathology, the development of therapeutic gel scaffolds, and the control of aging.

Staphylococcus aureus is the most common pathogen causing osteomyelitis, a hardly recoverable bone infection that generates significant burden to patients. Osteomyelitis mouse models have long and successfully served to provide phenomenological insights into both pathogenesis and host response. However, direct in situ monitoring of bone microbial pathogenesis and immune response at the cellular level is still conspicuously missing in the published literature. Here, we update a standard pyogenic osteomyelitis in Wistar rat model, in order to investigate bacterial localization and immune response in osteomyelitis of rat tibia upon adding in situ analyses by spectrally resolved Raman spectroscopy. Raman experiments were performed one and five weeks post infections upon increasing the initial dose of bacterial inoculation in rat tibia. Label-free in situ Raman spectroscopy clearly revealed the presence of Staphylococcus aureus through exploiting peculiar signals from characteristic carotenoid staphyloxanthin molecules. Data were collected as a function of both initial bacteria inoculation dose and location along the tibia. Such strong Raman signals, which relate to single and double bonds in the carbon chain backbone of carotenoids, served as efficient bacterial markers even at low levels of infection. We could also detect strong Raman signals from cytochrome c (and its oxidized form) from bone cells in response to infection and inflammatory paths. Although initial inoculation was restricted to a single location close to the medial condyle, bacteria spread along the entire bone down to the medial malleolus, independent of initial infection dose. Raman spectroscopic characterizations comprehensively and quantitatively revealed the metabolic state of bacteria through specific spectroscopic biomarkers linked to the length of staphyloxanthin carbon chain backbone. Moreover, the physiological response of eukaryotic cells could be quantified through monitoring the level of oxidation of mitochondrial cytochrome c, which featured the relative intensity of the 1644 cm⁻¹ signal peculiar to the oxidized molecules with respect to its pyrrole ring-breathing signal at 750 cm⁻¹, according to the previously published literature. In conclusion, we present here a novel Raman spectroscopic approach indexing bacterial concentration and immune response in bone tissue. This new approach enables locating and characterizing in situ bone infections, inflammatory host tissue reactions, and bacterial resistance/adaptation.

Bone marrow stimulation is a treatment for articular cartilage injuries that promotes cartilage repair by inducing the migration and accumulation of mesenchymal stem cells (MSCs), but often results in fibrocartilage with limited durability. This study aimed to investigate the effect of hypoxic conditions on cartilage repair using a rat osteochondral defect model. Osteochondral defects (1.0 mm in diameter) were created in the femoral trochlear groove, and rats were exposed to hypoxic conditions (12% O₂) for 4 weeks postoperatively. Histological analysis was performed, and protein expression of hypoxia-inducible factor-1α (HIF-1α) and SRY-box transcription factor 9 (SOX9) in the repair tissue was evaluated after 1 week. As a result, after 1 week, protein expression of HIF-1α and SOX9 in the Hypoxia group was significantly increased compared to the Normoxia group. After 4 weeks, the Hypoxia group exhibited a hyaline cartilage-like tissue structure with a significantly lower Modified Wakitani score compared to the Normoxia group. Furthermore, after 4 weeks, the inhibition of HIF-1α suppressed cartilage repair. These findings suggest that hypoxic conditions promote SOX9 expression via HIF-1α during the early phase of MSC chondrogenic differentiation and promote the formation of hyaline cartilage-like repair tissue. In conclusion, bone marrow stimulation under hypoxic conditions may enhance the repair effect on articular cartilage injuries.

Naked mole-rats are extremely long-living rodents with a maximum lifespan of 37 years, and their cellular aging and tissue aging are almost nonexistent. Therefore, in this study, we aim to analyze the extracellular matrix of the temporomandibular joint (TMJ) of naked mole-rats at the molecular level and explore the molecules involved in anti-aging and their localization. Micro-computed tomography (CT) scans revealed increased mineral density and wear of the mandibular condyle in aged mice. Conversely, CT scans did not reveal wear of the mandibular condyle in naked mole-rats, and histological analysis did not reveal wear of the articular disk. Using various spectroscopies and artificial intelligence (AI), we found that the articular disk of naked mole-rats is composed of a cartilage-like layer with hyaluronic acid and collagen fibers with varying orientations, which is thought to have relieved mechanical stress and have protected the mandibular condyle. These results suggest that not only the amount, but also the spatial distribution of the extracellular matrix is important for the anti-aging properties of the TMJ, and may contribute to elucidating the pathology of TMJ disorders and other degenerative conditions and developing therapeutic drugs.

Cisplatin (CDDP) is an anticancer drug that is frequently used to treat head and neck cancers; however, it may cause oral mucositis. The discontinuation of CDDP may be required for some patients with a severe status, and the control of oral mucositis is extremely important. β-Cryptoxanthin (β-cry), a carotenoid, exerts anti-inflammatory effects. Its inhibition of 5-FU-induced inflammatory responses was recently demonstrated. However, the effects of β-cry on CDDP-induced oral mucositis remain unclear. In the present study, we stimulated human oral mucosa-derived keratinocytes (hOMK) and fibroblasts (hOMF) with CDDP, added β-cry, and examined its effects, with a focus on the production of inflammatory cytokines, matrix metalloproteinase (MMPs), and reactive oxygen species (ROS). CDDP increased the mRNA expression and production of inflammatory cytokines and MMPs both in hOMK and hOMF. However, increases in IL-6 and MMP-9 mRNA expression levels and IL-6 production in CDDP-treated hOMK and hOMF were inhibited by β-cry. Furthermore, the production of ROS and the rate of SA-β-gal-positive cells were increased by CDDP, but were not affected by β-cry. CDDP may induce oral mucositis by increasing the levels of inflammatory cytokines, MMPs, and ROS. β-cry partially inhibited CDDP-induced increases in inflammatory cytokines and MMPs, suggesting its potential to attenuate the symptoms of chemotherapy-related oral mucositis.

Bone marrow stimulation is a treatment for articular cartilage injuries that promotes cartilage repair by creating small holes to induce mesenchymal stem cells (MSCs). However, most of the repair tissue is fibrocartilage, with poor mechanical durability and functionality. Recent studies have demonstrated that hypoxic conditions promote the chondrogenic differentiation of MSCs, but the effects of hypoxic conditions on cartilage repair in vivo remain unclear. Therefore, this study aimed to investigate the effect of hypoxic conditions on cartilage repair using a rat osteochondral defect model. Osteochondral defects, 1.0 mm in diameter, were created in the femoral trochlear groove. After surgery, rats were bred under hypoxic conditions (12%) for 4 weeks, and histological analysis was performed. Protein expression of hypoxia-inducible factor-1α (HIF-1α) and SRY-box transcription factor 9 (SOX9) in the repair tissue was evaluated at 1 week. As a result, Hypoxia group exhibited hyaline cartilage-like tissue structure and early expression of HIF-1α and SOX9 compared to Normoxia group. These findings suggest that hypoxic conditions promote SOX9 expression via HIF-1α during the early phase of MSC chondrogenic differentiation, and formation of hyaline cartilage-like repair tissue. In conclusion, bone marrow stimulation with hypoxic conditions may enhance the repair effect on articular cartilage injuries.

We investigated the effects of belt electrode-skeletal muscle electrical stimulation (B-SES) on muscle atrophy in collagen-induced arthritis (CIA) rats. Twenty-eight 8-week-old male Dark Agouti rats were immunized with type II collagen and Freund’s incomplete adjuvant (day 0). From days 14 to 28, 18 rats received B-SES (50 Hz) four times only on the right hindlimb (STIM), while the contralateral left hindlimb remained unstimulated. Both hindlimbs of 10 untreated CIA rats were defined as controls (CONT). Paw volume was measured every other day. On day 28, the muscle weight, histology, and gene expression of the soleus and extensor digitorum longus (EDL) were analyzed. B-SES did not worsen paw volume throughout the experimental period. Compared with CONT, the muscle weight and fiber cross-sectional area of the soleus were higher in STIM. The expression of muscle degradation markers (atrogin-1 and MuRF-1) in the soleus and EDL was lower in the STIM group than that in the CONT group. In contrast, B-SES did not significantly affect the expression of muscle synthesis (Eif4e and p70S6K) and mitochondrial (PGC-1α) markers. B-SES prevents muscle atrophy in CIA rats by reducing muscle degradation without exacerbating arthritis, demonstrating its promising potential as an intervention for RA-induced muscle atrophy.