Outer membrane vesicles (OMVs) are nanoscale vesicles secreted by Gram-negative bacteria. As a unique bacterial secretion, OMV secretion can help bacteria maintain the outer membrane stability or remove harmful substances. Studies have shown that local separation of outer membrane and peptidoglycan layers led by abnormalities in outer membrane protein function, abnormal structure or excessive accumulation of LPS, and erroneous accumulation of phospholipids in the outer leaflet, which can all lead to bacterial outer membrane protrusion and eventually bud formation of OMVs. Since OMVs are mainly composed of bacterial outer membrane and periplasmic components, the pathogen associated molecular patterns (PAMPs) on their surface can trigger strong immune responses. For example, OMVs can recruit and activate neutrophils, polarize macrophages to secrete large amounts of inflammatory factors. More importantly, OMVs can act as adjuvants to induce dendritic cell (DC) maturation to enhance adaptive immune response in the body. At the same time, OMVs are derived from bacteria, which make it easy to modify. The methods by genetic engineering and others can improve their tumor targeting, give them new functions, or reduce their immunotoxicity, which is conducive to their application in tumor therapy. OMVs not only induce apoptosis or pyroptosis of tumor cells, but also regulate the host immune system, which makes OMVs themselves have a certain killing effect on tumors. In addition, the tendency of neutrophils to inflammatory tumor sites and the formation of neutrophil extracellular traps enable OMVs to target tumor sites, and the suitable size and the characteristic that they are easily taken up by DCs give OMVs a certain lymphatic targeting ability. Therefore, OMVs are often employed as excellent drug or vaccine carriers in tumor therapy. This review mainly discusses the biological mechanism of OMVs, the regulatory effects of OMVs on immune cells, the functional modification strategies of OMVs, and their research progress in tumor therapy.

ObjectiveTo determine the value of MRI blooming sign in differentiating benign and malignant small breast masses and investigate its radiologic-pathologic correlation. MethodsThis retrospective study included 554 small breast masses （291 malignant and 263 benign） which were ≤ 2 cm and validated by pathology analysis between June 2016 and September 2020. All 554 patients underwent breast MRI. The clinical characteristics and MR features were analyzed. Univariate and multivariate regression analysis were performed to identify the independent risk factors of breast cancer. Two diagnostic models were constructed based on independent risk factors （model 1 included blooming sign and model 2 didn’t）. ROC curve was used to evaluate the diagnostic performances of the two models. The histological changes of peritumoral tissues in all small masses were analyzed. ResultsThe blooming sign was positive in 199 cases （68.4%） of the malignant masses and 25 cases （9.5%） of the benign ones （P＜0.05）. Univariate and multivariate regression analysis showed that age， lesion diameter， margin， ADC value， time signal intensity curve type and blooming sign were independent risk factors for breast cancer. Odds ratio were 1.065， 4.515， 2.811， 0.013， 3.487 and 13.894， respectively. Their corresponding 95%CI were （1.034， 1.097）， （2.368， 8.608）， （1.954， 4.045）， （0.004， 0.049）， （2.087， 5.826） and （7.026， 27.477）， respectively. The diagnostic performance of model 1 （blooming sign included） was better than that of model 2 （blooming sign not included； AUC： 0.938 vs 0.897， P < 0.05）. Histopathological analysis showed that the blooming sign was related to peritumoral lymphocyte infiltration and vascular proliferation. ConclusionsMRI blooming sign is helpful for distinguishing breast cancer from benign masses. The correlated histopathological basis may be peritumoral lymphocyte infiltration and neovascularization.

【Objective】 To analyze the metagenomics and microbiology of voluntary blood donors in China, so as to assess the potential threats of emerging infectious diseases to the safety of blood transfusion. 【Methods】 12 300 plasma samples (10 mL each) collected by central blood stations in Chongqing, Liuzhou, Urumqi, Mianyang, Wuhan, Nanjing, Mudanjiang, and Dehong Prefecture area from 2012 to 2018 were subjected to total DNA extraction after ultracentrifugation (32 000 rpm/min, centrifugal radius 91.9 mm) in minipools of 160 donations. The metagenomic library was constructed, and deep sequencing was conducted by Illumina Hiseq 4 500. By comparing with reference sequences of bacteria, fungi, parasites and viruses, metagenomic data were analyzed, classification of microbes were identified, and potentially harmful pathogens were evaluated. 【Results】 A total of 632 GB clean data were obtained by deep sequencing, and the top three pathogens were Pseudomonas(0.561 1%), Burkholderia(0.468 7%) and Serratia(4.242 0%). Pathogens with potential threat which could be transmitted by blood transfusion or blood products were found, such as human parvovirus B19(0.126 6%), Leishmania spp(1.348 5%) and Toxoplasma gondii(0.615 8%). 【Conclusion】 Our study analyzed metagenomics of voluntary blood donors in parts of China and revealed pathogens that may cause potential harm to blood safety, which were helpful for targeted prevention and control of emerging infectious diseases.