PTH1-34 inhibited TNF-α expression and antagonized TNF-α-induced MMP13 expression in MIO mice

Promoting Articular Cartilage Regeneration through Microenvironmental Regulation

In recent years, as the aging population continues to grow, osteoarthritis (OA) has emerged as a leading cause of disability, with its incidence rising annually. Current treatments of OA include exercise and medications in the early stages and total joint replacement in the late stages. These approaches only relieve pain and reduce inflammation; however, they have significant side effects and high costs. Therefore, there is an urgent need to identify effective treatment methods that can delay the pathological progression of this condition. The changes in the articular cartilage microenvironment, which are complex and diverse, can aggravate the pathological progression into a vicious cycle, inhibiting the repair and regeneration of articular cartilage. Understanding these intricate changes in the microenvironment is crucial for devising effective treatment modalities. By searching relevant research articles and clinical trials in PubMed according to the keywords of articular cartilage, microenvironment, OA, mechanical force, hypoxia, cytokine, and cell senescence. This study first summarizes the factors affecting articular cartilage regeneration, then proposes corresponding treatment strategies, and finally points out the future research direction. We find that regulating the opening of mechanosensitive ion channels, regulating the expression of HIF-1, delivering growth factors, and clearing senescent cells can promote the formation of articular cartilage regeneration microenvironment. This study provides a new idea for the treatment of OA in the future, which can promote the regeneration of articular cartilage through the regulation of the microenvironment so as to achieve the purpose of treating OA.

Temporal progression of subchondral bone alterations in OA models involving induction of compromised meniscus integrity in mice and rats: A scoping review

OBJECTIVE

To categorize the temporal progression of subchondral bone alterations induced by compromising meniscus integrity in mouse and rat models of knee osteoarthritis (OA).

METHOD

Scoping review of investigations reporting subchondral bone changes with appropriate negative controls in the different mouse and rat models of OA induced by compromising meniscus integrity.

RESULTS

The available literature provides appropriate temporal detail on subchondral changes in these models, covering the entire spectrum of OA with an emphasis on early and mid-term time points. Microstructural changes of the subarticular spongiosa are comprehensively described; those of the subchondral bone plate are not. In mouse models, global subchondral bone alterations are unidirectional, involving an advancing sclerosis of the trabecular structure over time. In rats, biphasic subchondral bone alterations begin with an osteopenic degeneration and loss of subchondral trabeculae, progressing to a late sclerosis of the entire subchondral bone. Rat models, independently from the applied technique, relatively faithfully mirror the early bone loss detected in larger animals, and the late subchondral bone sclerosis observed in human advanced OA.

CONCLUSION

Mice and rats allow us to study the microstructural consequences of compromising meniscus integrity at high temporal detail. Thickening of the subchondral bone plate, an early loss of thinner subarticular trabecular elements, followed by a subsequent sclerosis of the entire subchondral bone are all important and reliable hallmarks that occur in parallel with the advancing articular cartilage degeneration. Thoughtful decisions on the study design, laterality, selection of controls and volumes of interest are crucial to obtain meaningful data.

Explorative research on glucolipid metabolism and levels of adipokines in pseudohypoparathyroidism type 1 patients

BACKGROUND

Pseudohypoparathyroidism type 1 (PHP1) is a rare disease featuring hypocalcemia and elevated PTH level. Though disturbed calcium and phosphorus metabolism under PTH resistant have been widely studied, glucolipid metabolism abnormalities observed in PHP1 patients have received little attention. The aim of this research is to explore the glucolipid metabolism features in a rather large cohort of PHP1 patient. In the current study, PHP1 patients and primary hyperparathyroidism patients as well as normal control were recruited for the investigation. Glucolipid metabolic indices as well as the level of four adipokines were examined.

RESULTS

A total of 49 PHP1 patients, 64 PHPT patients and 30 healthy volunteers were enrolled. A trend of higher HOMA-β index was found in PHP1 patients than normal controls (median 97.08% vs 68.19%, p = 0.060). Both the PHP1 and PHPT group presented with significantly lower TNFα level compared to normal controls (average 10.74 pg/ml and 12.53 pg/ml vs 15.47 pg/ml, p = 0.002 and 0.041, respectively). FGF21 level was significantly higher in PHPT group than in PHP1 group (median 255.74 pg/ml vs 167.46 pg/ml, p = 0.019). No significant difference in glucolipid metabolic indices and adipokines was found between PHP1A or PHP1B patients and normal controls, while overweight/obese PHP1 patients tended to have higher leptin than normal-BMI cases (p = 0.055). Multiple linear regression analysis showed BMI rather than PTH or HOMA-IR to be an independent variable of leptin in PHP1.

CONCLUSION

Metabolic stress given upon especially overweight PHP1 patients may resulted in possible β-cell compensation. Elevated TNFα may be related with hyper-PTH level regardless of calcium level.

Human Umbilical Cord-Derived Mesenchymal Stem Cells Alleviate Psoriasis Through TNF-α/NF-κB/MMP13 Pathway

Psoriasis is a chronic, immune-mediated disease that affects 2-3% of the global population. Recently, mesenchymal stem cells (MSCs) have been used to alleviate psoriasis. However, the therapeutic mechanisms of MSCs remain unclear. Matrix metalloproteinase-13 (MMP13), a member of the MMPs family, is the key enzyme in the cleavage of type II collagen and plays a pivotal role in extracellular matrix (ECM) remodeling. Here, it was found that Mmp13 was upregulated in the skin lesions of an imiquimod-induced mouse model, which was downregulated after intravenous infusion of human umbilical cord MSCs (hUC-MSCs). Knockdown of MMP13 inhibited the proliferation of keratinocytes and arrested the cell cycle in G1 stage. In addition, hUC-MSCs were co-cultured with THP-1 or PMA-stimulated THP-1 directly in vitro to simulate the fate of systematically infused hUC-MSCs. The level of TNF-α was decreased in the supernatant of co-cultured hUC-MSCs and THP-1 or PMA-stimulated THP-1. Moreover, it was identified that TNF-α upregulated MMP13 through the NF-κB pathway in keratinocytes. In conclusion, we propose that systematically infused hUC-MSCs exert a therapeutic effect on psoriasis through the TNF-α/NF-κB/MMP13 pathway.

Potential effects of teriparatide (PTH (1-34)) on osteoarthritis: a systematic review

Osteoarthritis (OA) is a common and prevalent degenerative joint disease characterized by degradation of the articular cartilage. However, none of disease-modifying OA drugs is approved currently. Teriparatide (PTH (1-34)) might stimulate chondrocyte proliferation and cartilage regeneration via some uncertain mechanisms. Relevant therapies of PTH (1-34) on OA with such effects have recently gained increasing interest, but have not become widespread practice. Thus, we launch this systematic review (SR) to update the latest evidence accordingly. A comprehensive literature search was conducted in PubMed, Web of Science, MEDLINE, the Cochrane Library, and Embase from their inception to February 2022. Studies investigating the effects of the PTH (1-34) on OA were obtained. The quality assessment and descriptive summary were made of all included studies. Overall, 307 records were identified, and 33 studies were included. In vivo studies (n = 22) concluded that PTH (1-34) slowed progression of OA by alleviating cartilage degeneration and aberrant remodeling of subchondral bone (SCB). Moreover, PTH (1-34) exhibited repair of cartilage and SCB, analgesic, and anti-inflammatory effects. In vitro studies (n = 11) concluded that PTH (1-34) was important for chondrocytes via increasing the proliferation and matrix synthesis but preventing apoptosis or hypertrophy. All included studies were assessed with low or unclear risk of bias in methodological quality. The SR demonstrated that PTH (1-34) could alleviate the progression of OA. Moreover, PTH (1-34) had beneficial effects on osteoporotic OA (OPOA) models, which might be a therapeutic option for OA and OPOA treatment.

A discovery of clinically approved Panlongqi Tablet for repositioning to treat osteoarthritis by inhibiting PI3K/AKT activation

BACKGROUND

Panlongqi Tablet (PLQT) is a Chinese patent drug composed of 29 kinds of traditional Chinese medicines. Clinical practice has shown that PLQT can relieve osteoarthritis-caused joint pain, but its effects and mechanisms in other pathological links of osteoarthritis have not been characterized.

PURPOSE

The purpose of this study is to reposition the pharmacodynamic effects of PLQT through network pharmacology analysis combined with experimental validation, and also to preliminarily explore its possible mechanism.

METHODS

On the basis of integrating the relevant targets of PLQT in multiple drug databases and osteoarthritis-related targets in the disease database, an interaction network of related genes was constructed. The hub candidate targets of PLQT in the treatment of osteoarthritis were determined by calculating the main network topological characteristics, The specific functions and pathways of these targets acting on osteoarthritis were modularly analyzed. In addition, the modified Hulth-induced rat model of osteoarthritis and IL-1β-induced in vitro model of osteoarthritis were established to further validate the potential efficacy and possible mechanism of PLQT.

RESULTS

A total of 138 key targets related to osteoarthritis were selected based on topological parameters, and their biological functions were mainly enriched in four over-expressed modules of cartilage degeneration, inflammatory response, immune response, and subchondral bone metabolism. The hub candidate targets had the highest enrichment degree in the TLR4-RAC1-PIK3CA-Akt-NFκB signaling axis of the PI3K/Akt signaling pathway. In vivo results showed that PLQT treatment significantly inhibited the degeneration of proteoglycan and collagen in the cartilage of osteoarthritis rats, suppressed chondrocyte apoptosis, and reduced the Mankin score of joints. Moreover, PLQT alleviated synovial inflammation, reduced the Krenn score of synovium, inhibited the formation of osteophytes in osteoarthritis rats, reduced the bone mineral density (BMD), fractional bone volume (BV/TV), and trabecular thickness (Tb.Th.), as well as increased the trabecular separation (Tb.Sp.) of subchondral bone and the thickness of the subchondral bone plate (SBP.Th.). PLQT suppressed the expressions of TLR4, RAC1, PIK3CA, p-Akt, MMP-13, and ADAMTS-5 in the cartilage, and inhibited the expression of NFκB p65 in the chondrogenic nucleus. Meanwhile, as downstream effector factors of the predictive pathways, the levels of serum interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide (NO), and prostaglandin E₂ (PGE₂) were decreased after PLQT treatment. In vitro results also showed that PLQT could inhibit the expression of key proteins and downstream effector factors of the signaling axis, and this inhibition disappeared when pathway agonists were added.

CONCLUSION

PLQT exerted pharmacological effects on the key pathological links of osteoarthritis including chondrocyte apoptosis, extracellular matrix degradation, inflammation, and subchondral bone metabolism by inhibiting the TLR4-RAC1-PIK3CA-Akt-NFκB axis-related proteins.

AZ-628 delays osteoarthritis progression via inhibiting the TNF-α-induced chondrocyte necroptosis and regulating osteoclast formation

As a degenerative disease, the pathogenesis and treatment of osteoarthritis (OA) are still being studied. The prevailing view is that articular cartilage dysfunction plays an essential role in the development of osteoarthritis. Similarly, dynamic bone remodeling dramatically influences the development of osteoarthritis. The inflammatory response is caused by the overexpression of inflammatory factors, among which tumor necrosis factor-α is one of the main causes of OA, and its sources include the secretion of chondrocytes themselves and osteoclast secretion of subchondral bone. Moreover, TNF-α-induced activation of RIP1, RIP3, and MLKL has been shown to play an important role in cell necroptosis and inflammatory responses. In vitro, AZ-628 alleviates chondrocyte inflammation and necroptosis by inhibiting the NF-κB signaling pathway and RIP3 activation instead of RIP1 activation. AZ-628 also reduces osteoclast activity, proliferation and differentiation, and release of inflammatory substances by inhibiting autophagy, MAPK, and NF-κB pathways. Similarly, the in vivo study demonstrated that AZ-628 could inhibit chondrocyte breakdown and lower osteoclast formation and bone resorption, thereby slowing down subchondral bone changes induced by dynamic bone remodeling and reversing the progression of osteoarthritis in mice. The results of this study indicate that AZ-628 could be used to treat OA byinhibiting chondrocyte necroptosis and regulating osteoclast formation.

Chondroprotective Effects of Gubitong Recipe via Inhibiting Excessive Mitophagy of Chondrocytes

Objective

Osteoarthritis (OA) is the most common degenerative joint disorder and a leading cause of disability. A previous randomized controlled trial has shown that Gubitong (GBT) recipe can improve OA-related symptoms and articular function without noticeable side effects. However, the underlying mechanisms remain unclear. This study aims to explore the therapeutic mechanisms of the GBT recipe for OA through in vivo and in vitro experiments.

Methods

Rats of the OA model were established by Hulth surgery and intervened with the GBT recipe and then were subjected to pathological assessment of the cartilage. Matrix metalloproteinase 13 (MMP-13) expression in cartilage tissues was assessed by immunohistochemical staining. Chondrocytes were isolated from sucking rats and stimulated with LPS to establish an in vitro model. After intervened by water extraction of the GBT recipe, the fluorescent signal of Mtphagy Dye and mitochondrial membrane potential (Δψm) were detected to determine the states of mitophagy and mitochondrial dynamics of chondrocytes in vitro, respectively. Western blot test was used to detect levels of proteins related to catabolism of the cartilage matrix, mitophagy, and PI3K/AKT pathway.

Results

In in vivo experiments, the GBT recipe can effectively inhibit the cartilage degeneration of chondrocytes in OA rats, as well as markedly suppress the expression of MMP-13. In vitro experiments on LPS-induced chondrocytes exhibited increase in mitochondrial depolarization and excessive mitophagy, and the GBT recipe can alleviate these changes. LPS-stimulated chondrocytes showed increases in MMP-13, PINK1, and Parkin in cell lysates and LC3II/LC3I ratio in the mitochondrial fraction, and the GBT recipe can inhibit these increases in a dose-dependent manner. Moreover, the GBT recipe can attenuate the abnormal activation of PI3K/AKT pathway induced by LPS.

Conclusion

The GBT recipe exhibits chondroprotective effects through inhibiting excessive mitophagy of chondrocytes, which may be associated with its inhibitory effect on the abnormal activation of PI3K/AKT pathway.