Objective:To construct a mutant strain of hypervirulent Klebsiella pneumoniae NTHU-K2044 with hfq gene deletion and to analyze its biological characteristics. Methods:The hfq gene of NTUH-K2044 was knocked out by homologous recombination technology to construct △ hfq mutant strain. Its biological characteristics including growth rate, environmental stress tolerance, biofilm formation, capsular polysaccharide synthesis, resistance to neutrophil phagocytosis and lethality to Galleria mellonella larvae were analyzed by comparing with the wild-type strain using phenotypic experiments. Results:The △ hfq mutant strain of hypervirulent Klebsiella pneumoniae NTHU-K2044 was successfully constructed. Phenotypic experiments showed that the △ hfq mutant strain had significantly slower growth rate, smaller colonies and decreased hypermucoviscosity. Its growth was significantly inhibited under different environmental stress conditions such as pH9, pH5.5, 0.7 mmol/L SDS, 5% NaCl, 0.1% H 2O 2 and high temperature of 50℃. In terms of virulence and pathogenicity, the △ hfq mutant strain showed decreased ability to form biofilm and capsule, significantly down-regulated expression of magA and rmpA genes required for capsule synthesis, lower survival rate in the neutrophil bactericidal test and obviously reduced lethality to Galleria mellonella larvae. Conclusions:As a RNA chaperone, Hfq protein could participate in post-transcriptional regulation and play an important role in regulating the physiology, environmental adaptability and virulence of hypervirulent Klebsiella pneumoniae. This study provided reference for further study on hypervirulent Klebsiella pneumoniae.

In recent years, research on immunotherapy has made great progress. Currently, immunotherapy has made significant breakthrough, especially programmed death 1/programmed death-ligand 1 (PD-1/PD-L1) checkpoint inhibitors (e.g, Nivolumab, Pembrolizumab, Atezolizumab, Durvalumab and Avelumab, etc.) have brought clinical benefits to patients with various pathological types of lung cancer, including squamous cell carcinoma, adenocarcinoma and small cell lung cancer. In this paper, the application value and current status of PD-1/PD-L1 checkpoint inhibitors in lung cancer were comprehensively analyzed by reviewing and interpreting representative clinical studies. Based on the results of various large-scale clinical trials results, the indications of immunotherapy in lung cancer have been continuously broadened, and the details of immunotherapy have also been constantly optimized. However, immunotherapy still faces many challenges, such as the selection of immune combination strategies, the exploration of biomarkers, the management of adverse events, the feasibility of application of driver gene mutation population and so on. In this article, we made a systematic review about the latest progress of PD-1/PD-L1 checkpoint inhibitors in lung cancer, in order to provide cutting-edge reference for the clinical workers.
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Animals ; Antineoplastic Agents, Immunological ; therapeutic use ; B7-H1 Antigen ; antagonists & inhibitors ; genetics ; immunology ; Humans ; Immunotherapy ; Lung Neoplasms ; drug therapy ; genetics ; immunology ; Programmed Cell Death 1 Receptor ; antagonists & inhibitors ; genetics ; metabolism