Lidocaine induces ROCK-dependent membrane blebbing and subsequent cell death in rabbit articular chondrocytes

Buprenorphine has a concentration-dependent cytotoxic effect on equine chondrocytes in vitro

OBJECTIVE

To investigate the cytotoxic effects of 2 different concentrations of buprenorphine and compare them with bupivacaine and morphine on healthy equine chondrocytes in vitro.

SAMPLE

Primary cultured equine articular chondrocytes from 3 healthy adult horses.

PROCEDURES

Chondrocytes were exposed for 0 and 2 hours to the following treatments: media (CON; negative control); bupivacaine at 2.2 mg/mL (BUPI; positive control); morphine at 2.85 mg/mL (MOR); buprenorphine at 0.12 mg/mL (HBUPRE); or buprenorphine at 0.05 mg/mL (LBUPRE). Chondrocyte viability was assessed using live/dead staining, water-soluble tetrazolium salt-8 (WST-8) cytotoxic assay, LDH assay, and flow cytometry. All continuous variables were evaluated with a mixed ANOVA with treatment, time, and their interactions as the fixed effects and each horse as the random effect.

RESULTS

Buprenorphine showed a concentration-dependent chondrotoxic effect. The viability of chondrocytes was significantly decreased with exposure to HBUPRE and BUPI compared to CON, MOR, and LBUPRE.

CLINICAL RELEVANCE

Negligible chondrotoxic effects were observed in healthy cultured equine chondrocytes exposed to 0.05 mg/mL of buprenorphine, whereas higher concentrations (0.12 mg/mL) showed a marked cytotoxic effect. Based on these results, low concentrations of buprenorphine appear to be safe for intra-articular administration. Further evaluation of this dose in vivo is needed before recommending its clinical use.

General Caspase Inhibition in Primary Chondrogenic Cultures Impacts Their Transcription Profile Including Osteoarthritis-Related Factors

OBJECTIVE

The knowledge about functions of caspases, usually associated with cell death and inflammation, keeps expanding also regarding cartilage. Active caspases are present in the growth plate, and caspase inhibition in limb-derived chondroblasts altered the expression of osteogenesis-related genes. Caspase inhibitors were reported to reduce the severity of cartilage lesions in osteoarthritis (OA), and caspase-3 might represent a promising biomarker for OA prognosis. The objective of this investigation was to decipher the transcriptomic regulation of caspase inhibition in chondrogenic cells.

DESIGN

Limb-derived chondroblasts were cultured in the presence of 2 different inhibitors: Z-VAD-FMK (FMK) and Q-VD-OPH (OPH). A whole transcriptome RNA sequencing was performed as the key analysis.

RESULTS

The analysis revealed a statistically significant increase in the expression of 252 genes in the FMK samples and 163 genes in the OPH samples compared with controls. Conversely, there was a significant decrease in the expression of 290 genes in the FMK group and 188 in the OPH group. Among the top up- and downregulated genes (more than 10 times changed), almost half of them were associated with OA. Both inhibitors displayed the highest upregulation of the inflammatory chemokine Ccl5, the most downregulated gene was the one for mannose receptors Mrc1.

CONCLUSIONS

The obtained datasets pointed to a significant impact of caspase inhibition on the expression of several chondro-/osteogenesis-related markers in an in vitro model of endochondral ossification. Notably, the list of these genes included some encoding for factors associated with cartilage/bone pathologies such as OA.

Ferroptosis induces membrane blebbing in placental trophoblasts

Ferroptosis is a regulated, non-apoptotic form of cell death, characterized by hydroxy-peroxidation of discrete phospholipid hydroperoxides, particularly hydroperoxyl (Hp) forms of arachidonoyl- and adrenoyl-phosphatidylethanolamine, with a downstream cascade of oxidative damage to membrane lipids, proteins and DNA, culminating in cell death. We recently showed that human trophoblasts are particularly sensitive to ferroptosis caused by depletion or inhibition of glutathione peroxidase 4 (GPX4) or the lipase PLA2G6. Here, we show that trophoblastic ferroptosis is accompanied by a dramatic change in the trophoblast plasma membrane, with macro-blebbing and vesiculation. Immunofluorescence revealed that ferroptotic cell-derived blebs stained positive for F-actin, but negative for cytoplasmic organelle markers. Transfer of conditioned medium that contained detached macrovesicles or co-culture of wild-type target cells with blebbing cells did not stimulate ferroptosis in target cells. Molecular modeling showed that the presence of Hp-phosphatidylethanolamine in the cell membrane promoted its cell ability to be stretched. Together, our data establish that membrane macro-blebbing is characteristic of trophoblast ferroptosis and can serve as a useful marker of this process. Whether or not these blebs are physiologically functional remains to be established.

Ex Vivo Expanded Human Vγ9Vδ2 T-Cells Can Suppress Epithelial Ovarian Cancer Cell Growth

γδ-T-cells have attracted attention because of their potent cytotoxicity towards tumors. Most γδ-T-cells become activated via a major histocompatibility complex (MHC)-independent pathway by the interaction of their receptor, Natural Killer Group 2 Member D (NKG2D) with the tumor-specific NKG2D ligands, including MHC class I-related chain A/B (MICA/B) and UL16-binding proteins (ULBPs), to kill tumor cells. However, despite their potent antitumor effects, the treatment protocols specifically targeting ovarian tumors require further improvements. Ovarian cancer is one of the most lethal and challenging female malignancies worldwide because of delayed diagnoses and resistance to traditional chemotherapy. In this study, we successfully enriched and expanded γδ-T-cells up to ~78% from peripheral blood mononuclear cells (PBMCs) with mostly the Vγ9Vδ2-T-cell subtype in the circulation. We showed that expanded γδ-T-cells alone exerted significant cytotoxic activities towards specific epithelial-type OVCAR3 and HTB75 cells, whereas the combination of γδ-T cells and pamidronate (PAM), a kind of aminobisphosphonates (NBPs), showed significantly enhanced cytotoxic activities towards all types of ovarian cancer cells in vitro. Furthermore, in tumor xenografts of immunodeficient NSG mice, γδ-T-cells not only suppressed tumor growth but also completely eradicated preexisting tumors with an initial size of ~5 mm. Thus, we concluded that γδ-T-cells alone possess dramatic cytotoxic activities towards epithelial ovarian cancers both in vitro and in vivo. These results strongly support the potential of clinical immunotherapeutic application of γδ-T-cells to treat this serious female malignancy.

P2X7 ionotropic receptor is functionally expressed in rabbit articular chondrocytes and mediates extracellular ATP cytotoxicity

Extracellular ATP regulates various cellular functions by engaging multiple subtypes of P2 purinergic receptors. In many cell types, the ionotropic P2X7 receptor mediates pathological events such as inflammation and cell death. However, the importance of this receptor in chondrocytes remains largely unexplored. Here, we report the functional identification of P2X7 receptor in articular chondrocytes and investigate the involvement of P2X7 receptors in ATP-induced cytotoxicity. Chondrocytes were isolated from rabbit articular cartilage, and P2X7 receptor currents were examined using the whole-cell patch-clamp technique. ATP-induced cytotoxicity was evaluated by measuring caspase-3/7 activity, lactate dehydrogenase (LDH) leakage, and prostagrandin E₂ (PGE₂) release using microscopic and fluorimetric/colorimetric evaluation. Extracellular ATP readily evoked a cationic current without obvious desensitization. This ATP-activated current was dose related, but required millimolar concentrations. A more potent P2X7 receptor agonist, BzATP, also activated this current but at 100-fold lower concentrations. ATP-induced currents were largely abolished by selective P2X7 antagonists, suggesting a predominant role for the P2X7 receptor. RT-PCR confirmed the presence of P2X7 in chondrocytes. Heterologous expression of a rabbit P2X7 clone successfully reproduced the ATP-induced current. Exposure of chondrocytes to ATP increased caspase-3/7 activities, an effect that was totally abrogated by P2X7 receptor antagonists. Extracellular ATP also enhanced LDH release, which was partially attenuated by the P2X7 inhibitor. The P2X7 receptor-mediated elevation in apoptotic caspase signaling was accompanied by increased PGE₂ release and was attenuated by inhibition of either phospholipase A₂ or cyclooxygenase-2. This study provides direct evidence for the presence of functional P2X7 receptors in articular chondrocytes. Our results suggest that the P2X7 receptor is a potential therapeutic target in chondrocyte death associated with cartilage injury and disorders including osteoarthritis.

Ultrasound-guided lower forearm median nerve block in open surgery for trigger thumb in 1- to 3-year-old children: A randomized trial

BACKGROUND AND AIM

Trigger thumb is a common hand disability in children and is primarily treated with open surgery. A conscious median nerve block can usually meet the requirements for trigger thumb-releasing surgery in adults; however, its effectiveness in children requires further clarification. The present study aims to demonstrate whether ultrasound-guided lower forearm median nerve blockade is a viable option for children undergoing open surgery for trigger thumb.

METHODS

A prospective randomized study was designed to compare median nerve blocks guided by ultrasonography with those guided by anatomic landmarks. Following induction of general anesthesia, the children received a median nerve block performed either by ultrasound-guided block of the lower forearm (group U) or landmark-based blocking at the proximal wrist crease level (group T) with a 0.2% ropivacaine injection. The success rates were compared between groups as the primary endpoint; additional sufentanil and propofol administration, anesthesia recovery time, and other secondary endpoints were also compared.

RESULTS

A total of 100 children (age 1-3 years) with ASA status I who were scheduled for open surgery for trigger thumb were included in this study (n = 50 per group). Thirty-seven children in group T and 50 children in group U underwent successful blocks. The rate of unsuccessful blockade was significantly lower in group U than group T (0% and 26%, respectively), and rate of additional sufentanil and propofol administration was also lower in group U than in group T.

CONCLUSION

Ultrasound-guided lower forearm median nerve block can provide more effective analgesia, a higher success rate, and lower general and local anesthetic dosages than the anatomic landmark-based blocking method in children undergoing open surgery for trigger thumb.

In Vitro Chondrotoxicity of Nonsteroidal Anti-inflammatory Drugs and Opioid Medications

BACKGROUND

A variety of medications are administered to the intra-articular space for the relief of joint pain. While amide-type local anesthetics have been extensively studied, there is minimal information regarding the potential chondrotoxicity of nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid medications.

PURPOSE

To investigate the in vitro chondrotoxicity of single-dose equivalent concentrations of ketorolac, morphine, meperidine, and fentanyl on human chondrocytes.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human cartilage was arthroscopically harvested from the intercondylar notch and expanded in vitro. Gene expression of cultured chondrocytes before treatment was performed with quantitative polymerase chain reaction for type I collagen, type II collagen, aggrecan, and SOX9. Chondrocytes were then exposed to 0.01%, 0.02%, and 0.04% morphine sulfate; 0.3% and 0.6% ketorolac tromethamine; 0.5%, 1.0%, and 1.5% meperidine hydrochloride; 0.0005% and 0.001% fentanyl citrate; and saline. A custom bioreactor was used to constantly deliver medications, with the dosage of each medication and the duration of exposure based on standard dose equivalents, medication half-lives, and differences in the surface area between the 6-well plates and the native joint surface. After treatment, a live/dead assay was used to assess chondrocyte viability and if minimal cell death was detected. A subset of samples after treatment was maintained to analyze for possible delayed cell death.

RESULTS

All tested concentrations of ketorolac and meperidine caused significantly increased cell death versus the saline control, demonstrating a dose-response relationship. The morphine and fentanyl groups did not show increased chondrotoxicity compared with the saline group, even after 2 weeks of additional culture.

CONCLUSION

In vitro exposure of chondrocytes to single-dose equivalent concentrations of either ketorolac or meperidine demonstrated significant chondrotoxicity, while exposure to morphine or fentanyl did not lead to increased cell death.

Revealing oxidative damage to enzymes of carbohydrate metabolism in yeast: An integration of 2D DIGE, quantitative proteomics, and bioinformatics

Clinical usage of lidocaine, a pro-oxidant has been linked with severe, mostly neurological complications. The mechanism(s) causing these complications is independent of the blockade of voltage-gated sodium channels. The budding yeast Saccharomyces cerevisiae lacks voltage-gated sodium channels, thus provides an ideal system to investigate lidocaine-induced protein and pathway alterations. Whole-proteome alterations leading to these complications have not been identified. To address this, S. cerevisiae was grown to stationary phase and exposed to an LC50 dose of lidocaine. The differential proteomes of lidocaine treatment and control were resolved 6 h post exposure using 2D DIGE. Amine reactive dyes and carbonyl reactive dyes were used to assess protein abundance and protein oxidation, respectively. Quantitative analysis of these dyes (⩾ 1.5-fold alteration, p ⩽ 0.05) revealed a total of 33 proteoforms identified by MS differing in abundance and/or oxidation upon lidocaine exposure. Network analysis showed enrichment of apoptotic proteins and cell wall maintenance proteins, while the abundance of proteins central to carbohydrate metabolism, such as triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase, and redox proteins superoxide dismutase and peroxiredoxin were significantly decreased. Enzymes of carbohydrate metabolism, such as phosphoglycerate kinase and enolase, the TCA cycle enzyme aconitase, and multiple ATP synthase subunits were found to be oxidatively modified. Also, the activity of aconitase was found to be decreased. Overall, these data suggest that toxic doses of lidocaine induce significant disruption of glycolytic pathways, energy production, and redox balance, potentially leading to cell malfunction and death.