Miao medicine Gu Yan Xiao tincture inhibits mTOR to stimulate chondrocyte autophagy in a rabbit model of osteoarthritis

ETHNOPHARMACOLOGICAL RELEVANCE

The Gu Yan Xiao tincture, a blend of traditional Chinese herbs, is traditionally used for osteoarthritis and related pain. This study investigated its mechanism of action in order to rationalize and validate its therapeutic use.

AIM OF THE STUDY

This study analyzed, in a rabbit model of knee osteoarthritis, whether and how Gu Yan Xiao tincture exerts therapeutic benefits by modulating chondrocyte autophagy.

MATERIALS AND METHODS

The active constituents within the GYX tincture were identified using liquid chromatography-mass spectrometry. The rabbit model was established by injecting animals with type II collagenase intra-articularly, and the effects of topically applied tincture were examined on osteoarthritis lesions of the knee using histopathology, micro-computed tomography and x-ray imaging. Effects of the tincture were also evaluated on levels of inflammatory cytokines, matrix metalloproteases, and autophagy in chondrocytes. As a positive control, animals were treated with sodium diclofenac.

RESULTS

The tincture mitigated the reduction in joint space, hyperplasia of the synovium and matrix metalloproteases in serum that occurred after injection of type II collagenase in rabbits. These therapeutic effects were associated with inhibition of mTOR and activation of autophagy in articular chondrocytes. Inhibiting mTOR with rapamycin potentiated the therapeutic effects of the tincture, while inhibiting autophagy with 3-methyladenine antagonized them.

CONCLUSIONS

Gu Yan Xiao tincture mitigates tissue injury in a rabbit model of osteoarthritis, at least in part by inhibiting mTOR and thereby promoting autophagy in chondrocytes. These results rationalize the use of the tincture not only against osteoarthritis but also potentially other diseases involving inhibition of autophagy in bones and joints.

Rapamycin Induces Autophagy and Reduces the Apoptosis of Podocytes Under a Stimulated Condition of Immunoglobulin A Nephropathy

Backgroud/Aims: The aim of this study was to investigate the potential renoprotective effect of rapamycin on the autophagy of podocytes treated with the supernatant of mesangial cells cultured with aggregated IgA1 (aIgA1) from immunoglobulin A nephropathy (IgAN) patients.

METHODS

Monomeric IgA1 (mIgA1) was isolated from the serum of IgAN patients or healthy volunteers, and then transformed to aIgA1 by heating. Subsequently, the aIgA1-mesangial cell supernatant was prepared by collecting the medium of mouse mesangial cells (MSC1097) cultured with aIgA1 (100 mg/L) from different IgAN patients or healthy volunteers for 48 h. Subsequently mouse podocytes (MPC5) were exposed to the supernatant of the aIgA1-mesangial cells for 24 h, using 100 mg/L aIgA1 from healthy volunteers as the control group or 100 mg/L aIgA1 from IgAN patients as the IgANs group, in RPMI 1640 medium. The MPC5 cells in the IgANs+Rap group were cultured with rapamycin (10 nmol/L) and the supernatant of MSC-1097 cells cultured with aIgA1 from IgAN patients in RPMI 1640 medium. Autophagy was assessed by western blot analysis (LC3, p62), electron microscopy, and immunofluorescence staining (LC3, p62, and CD63). The apoptosis of podocytes was evaluated by flow cytometry, and the expression of apoptosis-associated proteins cleaved-caspase-3 and caspase-3 were determined by western blot analysis.

RESULTS

Deficient autophagy, which was evident by decreased LC3-II and CD63 levels, caused accumulation of p62, and fewer autophagosomes were observed in the MPC5 cells cultured with the IgAN supernatant, along with stronger expression of cleaved caspase-3 and a higher apoptosis rate. Inhibition of autophagy was alleviated in the IgANs+Rap group. The LC3-II/LC3-I ratio increased by almost 30%, the accumulated p62 amount was reduced by 50%, and the number of autophagosomes per podocyte increased to about 7 times that of the IgAN groups. These results were confirmed by immunofluorescence staining. In addition, the apoptosis rate of MPC5 cells decreased from 19.88% in the IgAN group to 16.78% in the IgANs+Rap group, which was accompanied by a weaker expression level of cleaved caspase-3.

CONCLUSIONS

Rapamycin can reduce the apoptosis of podocytes by inducing autophagy in IgAN.

Decreased expression of autophagy protein LC3 and stemness (CD44+/CD24-/low) indicate poor prognosis in triple-negative breast cancer

This study evaluated the prognostic value of expression of autophagy protein light chain 3 (LC3) and the prognostic value of coexpression of LC3 and stemness markers CD44+/CD24-/low in triple-negative breast cancer (TNBC). LC3 and LC3/CD44+/CD24-/low immunophenotypes in tumor tissues were evaluated by immunohistochemistry in 67 TNBC patients. LC3- was expressed in 30 (44.78%) cases. The LC3- phenotype revealed a significant negative association with overall survival in both univariate (P = .0006) and multivariate (P = .0153) analyses. LC3-/CD44+/CD24-/low phenotype was observed in 24 (35.82%) of 67 TNBC patients. According to Kaplan-Meier analysis, prognosis was significantly worse in tumors with LC3-/CD44+/CD24-/low phenotype (P = .0280). Multivariate analysis indicated that LC3-/CD44+/CD24-/low phenotype was a significant independent prognostic indicator of overall survival. These results suggest that LC3 suppresses TNBC in mature tumor cells and cancer stem cells (CSCs). In conclusion, this study suggests that CSCs are linked to progression of autophagy in TNBC. During the progression and development of TNBC, autophagy of CSCs/progenitor cells is low. LC3-/CD44+/CD24-/low immunophenotype indicates a highly aggressive TNBC subgroup associated with a poor prognosis. This study investigated that LC3 deficiency may restrain TNBC in mature tumor cells and CSCs. Therefore, a reasonable inference is that inducing autophagy may be an effective therapeutic strategy in TNBC.

Impaired leukocytes autophagy in chronic kidney disease patients

BACKGROUND

Proteins and cytoplasmic organelles undergo degradation and recycling via autophagy; its role in patients with chronic kidney disease (CKD) is still unclear. We hypothesize that impaired kidney function causes autophagy activation failure.

METHODS

We included 60 patients with stage 5 CKD and 30 age- and sex-matched healthy subjects as controls. Patients with conditions that could affect autophagy were excluded. Leukocytes were isolated and analyzed from peripheral blood samples collected after overnight fasting and 2 h after breakfast.

RESULTS

Overnight fasting induced conversion of microtubule-associated protein-1 light chain 3 I to II (γLC3) and increased mRNA levels of the autophagy-related gene 5 (Atg5) and Beclin-1 in healthy subjects, which were nearly absent in CKD patients (p = 0.0001). Moreover, no significant difference in autophagy activation was observed between CKD patients with or without hemodialysis. Correlation studies showed that γLC3 was negatively associated with the left atrium size. Changes in Atg5 transcript levels were negatively associated with the left ventricular end-diastolic diameter, and changes in Beclin-1 transcript levels were negatively associated with the mitral inflow E- and A-wave sizes.

CONCLUSION

These data suggest that CKD patients have impaired autophagy activation, which cannot be reversed with hemodialysis and is closely related to their cardiac abnormalities.

NOX4 mediates cytoprotective autophagy induced by the EGFR inhibitor erlotinib in head and neck cancer cells

Most head and neck squamous cell carcinomas (HNSCCs) overexpress epidermal growth factor receptor (EGFR) and EGFR inhibitors are routinely used in the treatment of HNSCC. However, many HNSCC tumors do not respond or become refractory to EGFR inhibitors. Autophagy, which is a stress-induced cellular self-degradation process, has been reported to reduce the efficacy of chemotherapy in various disease models. The purpose of this study is to determine if the efficacy of the EGFR inhibitor erlotinib is reduced by activation of autophagy via NOX4-mediated oxidative stress in HNSCC cells. Erlotinib induced the expression of the autophagy marker LC3B-II and autophagosome formation in FaDu and Cal-27 cells. Inhibition of autophagy by chloroquine and knockdown of autophagy pathway genes Beclin-1 and Atg5 sensitized both cell lines to erlotinib-induced cytotoxicity, suggesting that autophagy may serve as a protective mechanism. Treatment with catalase (CAT) and diphenylene iodonium (DPI) in the presence of erlotinib suppressed the increase in LC3B-II expression in FaDu and Cal-27 cells. Erlotinib increased NOX4 mRNA and protein expression by increasing its promoter activity and mRNA stability in FaDu cells. Knockdown of NOX4 using adenoviral siNOX4 partially suppressed erlotinib-induced LC3B-II expression, while overexpression of NOX4 increased expression of LC3B-II. These studies suggest that erlotinib may activate autophagy in HNSCC cells as a pro-survival mechanism, and NOX4 may play a role in mediating this effect.

Autophagy-related protein LC3 and Beclin-1 in the first trimester of pregnancy

Autophagy is a degradation process that acts in response to environmental stressors. Recently, autophagy has been detected in normal term, preeclamptic and intrauterine growth-restricted placentas. The object of this work was to investigate the presence of autophagy in first trimester voluntary interruption of pregnancy placental villi by the expression of autophagy-related proteins, light chain 3 (LC3), and Beclin-1. In first trimester placental villi laser scanning confocal microscopy (LSCM) analysis revealed LC3 and Beclin-1 immunoreactivity prevalently located in villous cytotrophoblasts. Using LSCM, LC3, and Beclin-1 were localized to the cytoplasm of the trophoblast layer in human full-term placentas. Beclin-1 expression and LC3 activation were confirmed by western blotting. These data emphasize that autophagy activation is different among cytotrophoblasts and syncytiotrophoblasts depending on the gestational age and thus we speculate that autophagy might play a prosurvival role throughout human pregnancy.