Metabolic interventions combined with CTLA-4 and PD-1/PD-L1 blockade for the treatment of tumors: mechanisms and strategies / 医学前沿

Immunotherapies based on immune checkpoint blockade (ICB) have significantly improved patient outcomes and offered new approaches to cancer therapy over the past decade. To date, immune checkpoint inhibitors (ICIs) of CTLA-4 and PD-1/PD-L1 represent the main class of immunotherapy. Blockade of CTLA-4 and PD-1/PD-L1 has shown remarkable efficacy in several specific types of cancers, however, a large subset of refractory patients presents poor responsiveness to ICB therapy; and the underlying mechanism remains elusive. Recently, numerous studies have revealed that metabolic reprogramming of tumor cells restrains immune responses by remodeling the tumor microenvironment (TME) with various products of metabolism, and combination therapies involving metabolic inhibitors and ICIs provide new approaches to cancer therapy. Nevertheless, a systematic summary is lacking regarding the manner by which different targetable metabolic pathways regulate immune checkpoints to overcome ICI resistance. Here, we demonstrate the generalized mechanism of targeting cancer metabolism at three crucial immune checkpoints (CTLA-4, PD-1, and PD-L1) to influence ICB therapy and propose potential combined immunotherapeutic strategies co-targeting tumor metabolic pathways and immune checkpoints.

Role of inflammation and apoptosis in right ventricular dysfunction induced by injurious mechanical ventilation in rats / 中华危重病急救医学

Objective:To investigate whether myocardial inflammation and apoptosis are involved in right ventricular dysfunction (RVD) induced by injurious mechanical ventilation with high tidal volume (VT) in rats.Methods:Total 30 adult male SD rats were randomly divided into the control group (CON group), the low VT ventilation group (LVT group) and the injurious mechanical ventilation group (HVT group), with 10 rats in each group. The CON group was maintained spontaneous breathing, the LVT group and HVT group were ventilated with different VT 6 mL/kg and 20 mL/kg for 4 hours, respectively. The right jugular vein and the left carotid artery were catheterized and connected with the PowerLab biological signal acquisition and analysis system to record heart rate (HR), mean arterial pressure (MAP), right ventricular systolic pressure (RVSP), the maximum rate of rising of right ventricular pressure (+dp/dt max). Echocardiography was performed to measure left ventricular end-diastolic diameter (LVEDd), right ventricular end-diastolic diameter (RVEDd), tricuspid annulus plane systolic migration (TAPSE) and myocardial performance index (MPI). The rats were sacrified by cervical dislocation. Specimens of right ventricle tissues were taken for hematoxylin-eosin (HE) staining, and morphological changes of right ventricle tissues were observed under light microscope. Real time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to detect the mRNA and protein expressions of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), caspase-3, apoptosis-related proteins Bax and Bcl-2.Results:HR, MAP, +dp/dt max gradually decreased, while RVSP gradually increased in different group with the increase of VT ventilation. There was no significant difference between the CON group and LVT group. However, there was a statistically significant difference with respect to these index in HVT group as compared to CON group and LVT group [HR (bpm): 397.6±5.7 vs. 433.0±4.8, 441.6±7.8; MAP (mmHg, 1 mmHg≈0.133 kPa): 102.0±2.4 vs. 108.5±2.2, 110.6±2.1; +dp/dt max (mmHg/s): 2 357.65±62.80 vs. 2 661.27±55.62, 2 679.43±75.13; RVSP (mmHg): 28.8±1.0 vs. 22.6±10.8, 21.9±0.4; all P < 0.05]. Echocardiography findings showed that RVEDd/LVEDd and MPI gradually increased, TAPSE gradually decreased in different group with the increase of VT ventilation. There was no significant difference between the LVT group and CON group. However, there was a statistically significant difference with respect to these indexes in HVT group as compared to the CON group and LVT group [RVEDd/LVEDd: 0.36±0.02 vs. 0.26±0.01, 0.23±0.02; MPI: 1.23±0.03 vs. 0.84±0.04, 0.86±0.03; TAPSE (mm): 1.65±0.03 vs. 1.88±0.02, 1.91±0.04; all P < 0.05]. Histopathological observation of the right ventricle tissue showed that myocardial cells of the rats in the CON group were orderly arranged and uniformed in size. In the LVT group, there was a small amount of inflammatory cell infiltration in the myocardial interstitium, while in the HVT group, the myocardial cell arrangement was obviously disordered, the structure was obviously damaged, and more inflammatory cell infiltration was found. RT-PCR and Western blotting analysis showed that the mRNA and protein expressions of IL-6, TNF-α, caspase-3 and Bax in HVT group were significantly higher than those in the LVT group and CON group [mRNA expression (2 -ΔΔCt): IL-6 were 1.97±0.07 vs. 1.09±0.02, 1.02±0.03, TNF-α were 1.69±0.10 vs. 1.10±0.03, 1.05±0.04, caspase-3 were 1.82±0.09 vs. 1.08±0.02, 1.06±0.03, Bax were 2.19±0.14 vs. 1.07±0.03, 1.04±0.03; protein expression (gray value): IL-6 were 0.64±0.02 vs. 0.38±0.03, 0.31±0.04, TNF-α were 0.50±0.04 vs. 0.16±0.01, 0.15±0.01, caspase-3 were 0.58±0.02 vs. 0.29±0.01, 0.25±0.02, Bax were 0.50±0.03 vs. 0.21±0.01, 0.26±0.02; all P < 0.05], and the mRNA and protein expressions of Bcl-2 in the HVT group were lower than those in the LVT group and CON group [mRNA expression (2 -ΔΔCt): 1.23±0.05 vs. 1.43±0.05, 1.50±0.08; protein expression (gray value): 0.42±0.02 vs. 0.62±0.03, 0.65±0.03, all P < 0.05]. Conclusion:Myocardial inflammation and apoptosis may be involved in RVD induced by injurious mechanical ventilation.

Impacts of the clinics-pharmacy separation reform on outpatient CT utilization in Beijing / 中华医院管理杂志

Objective:To analyze the impacts of the clinics-pharmacy separation reform on outpatient CT utilization and provide policy recommendations for the rational use, refined management and subsequent price adjustment for large-scale imaging equipments.Methods:The number of outpatient CT examinations of a tertiary public hospital in Beijing from January 1st, 2015 to April 30th, 2019 was collected. Data were analyzed using single-and multi-group interrupted time series analysis model(ITS), along with qualitative interviews.Results:The number of CT examinations increased by 0.216 per 100 visits after the reform( P<0.001). The trend of changes(slope)in the number of CT examinations increased by 0.012 person-times/month( P<0.001). There were no statistically significant differences in the slope change of CT examinations between patients under Urban Employee Basic Medical Insurance and those under Urban Resident Basic Medical Insurance( P=0.504). Conclusions:The reform has significantly increased the utilization of outpatient CT examinations. However, the impacts of the reform may be similar among patients covered by different insurance systems. The qualitative interviews imply it as necessary to pay attention to the overworking status of relevant practitioners and be alert to the excessive use of large-scale imaging equipments.