Objective:To investigate the effect and underlying mechanism of isoliquiritigenin (ISL) on chondrocyte ferroptosis in a rat model of knee osteoarthritis (KOA).Methods:Sixty male SD rats were randomly divided into a sham group, KOA group, celecoxib group, ISL low-dose group, and ISL high-dose group. Except for the sham group, KOA models were induced in the other groups using the modified Hulth method. The ISL low-dose and high-dose groups received intraperitoneal injections of 10 mg/kg and 40 mg/kg ISL, respectively; the celecoxib group was orally administered 24 mg/kg celecoxib; the sham and KOA groups received equivalent doses of saline via intraperitoneal injection. Interventions were administered once daily for 8 weeks. Behavioral changes in the open field test, histopathological observations of cartilage, inflammatory cytokine detection, ferroptosis-related indicators, and Sirt1/Nrf2/GPX4 pathway protein expression were measured to determine the optimal ISL dose. Another 60 male SD rats were randomly divided into sham, KOA, ISL high-dose, Sirt1 inhibitor (EX-527), and ISL high-dose + EX-527 groups. KOA models were established in all groups except the sham group. The ISL high-dose group received 40 mg/kg ISL, the EX-527 group received 10 mg/kg EX-527, and the combination group received both. The sham and KOA groups were given saline. Interventions lasted 8 weeks. Histopathological staining evaluated cartilage damage and scoring; ELISA measured tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 levels in synovial fluid; iron deposition, Fe 2+, malonaldehyde (MDA), reactive oxygen species (ROS), superoxide dismutase (SOD), and glutathione (GSH) levels were assessed; Western blot analyzed Sirt1/Nrf2/GPX4 pathway proteins; immunohistochemistry detected Collagen II, Aggrecan, MMP-3, and MMP-13 expression. Results:The joint cartilage tissue damage in the ISL low-dose and high-dose rat groups was alleviated compared to the KOA group. The OARSI score, levels of TNF-α, IL-1β and IL-6 in joint fluid, iron deposition in cartilage tissue, Fe 2+, MDA and ROS levels were 8.33±1.86 and 4.50±1.52, respectively. 67.24±7.25 pg/ml, 42.06±5.12 pg/ml; 37.97±4.9 pg/ml, 23.75±4.12 pg/ml; 31.67±4.16 pg/ml, 20.91±3.28 pg/ml; 2.00±0.20, 1.53±0.14; 2.84±0.19 μmol/mg, 1.87±0.16 μmol/mg; 9.11±1.08 nmol/ml, 5.49±1.05 nmol/ml; 759.15±59.80 μmol/ml and 610.85±44.23 μmol/ml were lower than those in KOA group ( P<0.05), and the serum SOD and GSH contents were 12.12±1.52 U/ml and 16.79±2.14 U/ml, respectively. Compared with KOA group, the protein expressions of Sirt1, Nrf2, GPX4 and SLC7A11 were 0.70±0.11 and 0.96±0.13, 0.69±0.10 and 0.95±0.14, 0.51±0.06 and 0.87±0.12, 0.56±0.06 and 0.83±0.10, which were higher than those in KOA group ( P<0.05). The expressions of Acetyl-H4K16, ACSL4, MMP-3 and MMP-13 were 1.68±0.17 and 1.30±0.10, 1.39±0.12 and 0.97±0.10, 1.70±0.14 and 1.10±0.10, 1.64±0.15 and 1.28±0.10, which were lower than those of KOA group ( P<0.05). And the changes of these indexes were higher in Sirt1 inhibitor group. Compared with the ISL high-dose group, the ferroptosis-related indexes were significantly increased in the ISL high-dose+Sirt1 inhibitor group. Conclusion:ISL alleviates articular cartilage injury in KOA rats, and its mechanism is related to activating the Sirt1/Nrf2/GPX4 pathway and inhibiting ferroptosis.

Objective:To investigate the effect and underlying mechanism of isoliquiritigenin (ISL) on chondrocyte ferroptosis in a rat model of knee osteoarthritis (KOA).Methods:Sixty male SD rats were randomly divided into a sham group, KOA group, celecoxib group, ISL low-dose group, and ISL high-dose group. Except for the sham group, KOA models were induced in the other groups using the modified Hulth method. The ISL low-dose and high-dose groups received intraperitoneal injections of 10 mg/kg and 40 mg/kg ISL, respectively; the celecoxib group was orally administered 24 mg/kg celecoxib; the sham and KOA groups received equivalent doses of saline via intraperitoneal injection. Interventions were administered once daily for 8 weeks. Behavioral changes in the open field test, histopathological observations of cartilage, inflammatory cytokine detection, ferroptosis-related indicators, and Sirt1/Nrf2/GPX4 pathway protein expression were measured to determine the optimal ISL dose. Another 60 male SD rats were randomly divided into sham, KOA, ISL high-dose, Sirt1 inhibitor (EX-527), and ISL high-dose + EX-527 groups. KOA models were established in all groups except the sham group. The ISL high-dose group received 40 mg/kg ISL, the EX-527 group received 10 mg/kg EX-527, and the combination group received both. The sham and KOA groups were given saline. Interventions lasted 8 weeks. Histopathological staining evaluated cartilage damage and scoring; ELISA measured tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 levels in synovial fluid; iron deposition, Fe 2+, malonaldehyde (MDA), reactive oxygen species (ROS), superoxide dismutase (SOD), and glutathione (GSH) levels were assessed; Western blot analyzed Sirt1/Nrf2/GPX4 pathway proteins; immunohistochemistry detected Collagen II, Aggrecan, MMP-3, and MMP-13 expression. Results:The joint cartilage tissue damage in the ISL low-dose and high-dose rat groups was alleviated compared to the KOA group. The OARSI score, levels of TNF-α, IL-1β and IL-6 in joint fluid, iron deposition in cartilage tissue, Fe 2+, MDA and ROS levels were 8.33±1.86 and 4.50±1.52, respectively. 67.24±7.25 pg/ml, 42.06±5.12 pg/ml; 37.97±4.9 pg/ml, 23.75±4.12 pg/ml; 31.67±4.16 pg/ml, 20.91±3.28 pg/ml; 2.00±0.20, 1.53±0.14; 2.84±0.19 μmol/mg, 1.87±0.16 μmol/mg; 9.11±1.08 nmol/ml, 5.49±1.05 nmol/ml; 759.15±59.80 μmol/ml and 610.85±44.23 μmol/ml were lower than those in KOA group ( P<0.05), and the serum SOD and GSH contents were 12.12±1.52 U/ml and 16.79±2.14 U/ml, respectively. Compared with KOA group, the protein expressions of Sirt1, Nrf2, GPX4 and SLC7A11 were 0.70±0.11 and 0.96±0.13, 0.69±0.10 and 0.95±0.14, 0.51±0.06 and 0.87±0.12, 0.56±0.06 and 0.83±0.10, which were higher than those in KOA group ( P<0.05). The expressions of Acetyl-H4K16, ACSL4, MMP-3 and MMP-13 were 1.68±0.17 and 1.30±0.10, 1.39±0.12 and 0.97±0.10, 1.70±0.14 and 1.10±0.10, 1.64±0.15 and 1.28±0.10, which were lower than those of KOA group ( P<0.05). And the changes of these indexes were higher in Sirt1 inhibitor group. Compared with the ISL high-dose group, the ferroptosis-related indexes were significantly increased in the ISL high-dose+Sirt1 inhibitor group. Conclusion:ISL alleviates articular cartilage injury in KOA rats, and its mechanism is related to activating the Sirt1/Nrf2/GPX4 pathway and inhibiting ferroptosis.

Objective:To explore the diagnostic value of chest CT imaging in differential diagnosis between common-type COVID-19 and mycoplasma pneumonia (MP).Methods:From the January to February 2020, the clinical and imaging data of COVID-19 patients (diagnosed in the Affiliated Hospital of Jining Medical University, the Fourth People's Hospital of Jining and the Second People's Hospital of Jining) and MP patients (diagnosed in the Affiliated Hospital of Jining Medical University) were retrospectively collected and analyzed. Forty-three patients with common-type COVID-19 (28 males, 15 females, 43±14 years old) and 50 patients with MP (19 males, 31 females, 37±14 years old) were enrolled as COVID-19 group and MP group, respectively. The clinical manifestations, laboratory results and chest CT findings of these two groups were analyzed and compared.Results:(1) Clinical manifestations: there were more patients with muscle ache and asthenia in COVID-19 group than in MP group (χ 2=5.110, 4.834, P<0.05). No significant difference was found in fever and cough between two groups (χ 2=0.378, 0.097, P>0.05). (2) Laboratory examination: the procalcitonin level of cases in COVID-19 group was significantly lower than that in MP group (χ 2=12.263, P=0.001). No significant difference was found in leukocyte count, lymphocyte count, C-reactive protein level and erythrocyte sedimentation rate ( Z=-1.117, χ 2=2.410, 0.787, 0.800, all P>0.05) between two groups. (3) Chest CT findings bilateral lung involvement was found more in COVID-19 group than in MP group (χ 2=30.012, P<0.001); while the one lobe of ipilateral lung involvement was less in COVID-19 group than in MP group (χ 2=19.927, P<0.001); there was no significant difference in multiple lobes of ipilateral lung involvment between the two groups (χ 2=1.366, P>0.05). Ground glass, paving stone sign and air bronchus sign were found significantly more in COVID-19 group than in MP group (χ 2=30.171, 19.119, 9.790, all P<0.05); while the pulmonary consolidation, central lobular nodule and centripetal thickening of bronchus wall were found significantly less in COVID-19 group than in MP group (χ 2=25.450, 33.532, 48.553, all P<0.001). Conclusions:The clinical manifestations and laboratory examination have limited value in the differential diagnosis of common-type COVID-19 and MP, while chest CT imaging might be more valuable in the early differential diagnosis of these two diseases.