Disordered metabolic states, which are characterised by hypoxia and elevated levels of metabolites, particularly lactate, contribute to the immunosuppression in the tumour microenvironment (TME). Excessive lactate secreted by metabolism-reprogrammed cancer cells regulates immune responses via causing extracellular acidification, acting as an energy source by shuttling between different cell populations, and inhibiting the mechanistic (previously 'mammalian') target of rapamycin (mTOR) pathway in immune cells. This review focuses on recent advances in the regulation of immune responses by lactate, as well as therapeutic strategies targeting lactate anabolism and transport in the TME, such as those involving glycolytic enzymes and monocarboxylate transporter inhibitors. Considering the multifaceted roles of lactate in cancer metabolism, a comprehensive understanding of how lactate and lactate-targeting therapies regulate immune responses in the TME will provide insights into the complex relationships between metabolism and antitumour immunity.
Background
Coronavirus Disease 19 (COVID‐19) is a global health concern that has become a pandemic over the past few months. This study aims at understanding the clinical manifestations of COVID‐19 patients with pleural effusion.
Methods
COVID‐19 patients were retrospectively enrolled from the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. Pharyngeal swabs from patients were tested using real‐time polymerase chain reaction. Patients with COVID‐19 were divided into two groups based on their computed tomography (CT) scans for the presence of pleural effusion at admission. We compared the clinical features, laboratory findings, scans and clinical outcomes between the two groups.
Results
Pleural effusion was observed in 9.19% of the patients. Patients with pleural effusion were more likely to be severe or critical cases. Moreover, patients with pleural effusion were associated with increased mortality. Of the 799 discharged patients, patients with pleural effusion had longer hospital stays and duration of viral shedding since the onset of symptoms as compared with that for patients without pleural effusion. After discharge, 217 patients visited for a follow‐up CT re‐examination at the Union Hospital. The CT scans showed that patients with pleural effusion required a longer time to resolve the lung inflammation after the onset of COVID‐19 as compared with the time required by patients without pleural effusion.
Conclusion
This population of patients requires special attention and pleural effusion may be an indicator of poor prognosis in COVID‐19 patients.
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