Respiratory syncytial virus (RSV) infection is a major cause of severe lower respiratory illness in infants and young children, but the underlying mechanisms responsible for viral pathogenesis have not been fully elucidated. To date, no drugs or vaccines have been employed to improve clinical outcomes for RSV-infected patients. In this paper, we report that angiotensin-converting enzyme-2 (ACE2) protected against severe lung injury induced by RSV infection in an experimental mouse model and in pediatric patients. Moreover, ACE2 deficiency aggravated RSV-associated disease pathogenesis, mainly by its action on the angiotensin II type 1 receptor (AT1R). Furthermore, administration of a recombinant ACE2 protein alleviated the severity of RSV-induced lung injury. These findings demonstrate that ACE2 plays a critical role in preventing RSV-induced lung injury and suggest that ACE2 is a promising potential therapeutic target in the management of RSV-induced lung disease.

SARS-CoV-2 is the cause of the current global pandemic of COVID-19; this virus infects multiple organs, such as the lungs and gastrointestinal tract. The microbiome in these organs, including the bacteriome and virome, responds to infection and might also influence disease progression and treatment outcome. In a cohort of 13 COVID-19 patients in Beijing, China, we observed that the gut virome and bacteriome in the COVID-19 patients were notably different from those of five healthy controls. We identified a bacterial dysbiosis signature by observing reduced diversity and viral shifts in patients, and among the patients, the bacterial/viral compositions were different between patients of different severities, although these differences are not entirely distinguishable from the effect of antibiotics. Severe cases of COVID-19 exhibited a greater abundance of opportunistic pathogens but were depleted for butyrate-producing groups of bacteria compared with mild to moderate cases. We replicated our findings in a mouse COVID-19 model, confirmed virome differences and bacteriome dysbiosis due to SARS-CoV-2 infection, and observed that immune/infection-related genes were differentially expressed in gut epithelial cells during infection, possibly explaining the virome and bacteriome dynamics. Our results suggest that the components of the microbiome, including the bacteriome and virome, are affected by SARS-CoV-2 infections, while their compositional signatures could reflect or even contribute to disease severity and recovery processes.

MRNA therapy is a novel anticancer strategy based on in vitro transcription (IVT), which has potential for the treatment of malignant tumors. The outbreak of the COVID-19 pandemic in the early 21st century has promoted the application of mRNA technologies in SARS-CoV-2 vaccines, and there has been a great deal of interest in the research and development of mRNA cancer vaccines. There has been progress in a number of key technologies, including mRNA production strategies, delivery systems, antitumor immune strategies, etc. These technologies have accelerated the progress and clinical applications of mRNA therapy, overcoming problems encountered in the past, such as instability, inefficient delivery, and weak immunogenicity of mRNA vaccines. This review provides a detailed overview of the production, delivery systems, immunological mechanisms, and antitumor immune response strategies for mRNA cancer vaccines. We list some mRNA cancer vaccines that are candidates for cancer treatment and discuss clinical trials in the field of tumor immunotherapy. In addition, we discuss the immunological mechanism of action by which mRNA vaccines destroy tumors as well as challenges and prospects for the future.

Summary: Background: The novel coronavirus (CoV) severe acute respiratory syndrome (SARS)-CoV-2 outbreak started at the end of 2019 in Wuhan, China, and spread over 100 countries. SARS-CoV-2 uses the membrane protein Angiotensin I converting enzyme 2(ACE2) as a cell entry receptor. Indeed, it was reported that the balance of Renin-Angiotensin System (RAS), regulated by both ACE and ACE2, was altered in COVID-19 patients. It is controversial, however, whether commonly used anti-hypertensive drugs Angiotensin I converting enzyme inhibitor (ACEI) and Angiotensin II receptor blocker (ARB) shall be continued in the confirmed COVID-19 patients. This study was designed to investigate any difference in disease severity between COVID-19 patients with hypertension comorbidity. The included COVID-19 patients used ACEI, ARB, calcium channel blockers (CCB), beta blockers (BB), or thiazide to treat preexisting hypertension prior to the hospital were compared to patients who did not take any of those drugs. Methods: In this multicentre retrospective study, clinical data of 511 COVID-19 patients were analyzed. Patients were categorized into six sub-groups of hypertension comorbidity based on treatment using one of anti-hypertension drugs (ACEI, ARB, CCB, BB, thiazide), or none. A meta-analysis was performed to evaluate the use of ACEI and ARB associated with pneumonia using published studies. Findings: Among the elderly (age>65) COVID-19 patients with hypertension comorbidity, the risk of COVID-19-S (severe disease) was significantly decreased in patients who took ARB drugs prior to hospitalization compared to patients who took no drugs (OR=0·343, 95% CI 0·128-0·916, p=0·025). The meta-analysis showed that ARB use has positive effects associated with morbidity and mortality of pneumonia. Interpretation: Elderly (age>65) COVID-19 patients with hypertension comorbidity who are taking ARB anti-hypertension drugs may be less likely to develop severe lung disease compared to patients who take no anti-hypertension drugs. Funding: National Natural Science Foundation of China, Chinese Academy of Medical Sciences Research in context: Evidence before this study: We searched PubMed for articles published up to March 15, 2020 using keywords “2019-nCoV”, “SARS-CoV-2”, “novel coronavirus”, and COVID-19 AND “ARB”, and “angiotensin II receptor blocker” for papers published in both English and Chinese. We found three papers: one from our group, published in Science China Life Science that demonstrated an elevated Angiotensin II level in blood samples from COVID-19 patients; another a perspective article in Chinese recommending ACEI and ARBs as potential remedies for SARS-CoV-2 infections; the third a retrospective study in Chinese identifying no significant difference between ACEI/ARB associated with outcomes in 112 COVID-19 patients with CVD comorbidity. The International society of Hypertension stated on March 16 ^th , 2020: “there are no clinical data in human to show that ACE-inhibitors or ARBs either improve or worsen susceptibility to COVID-19 infection nor do they affect the outcomes of those infected”. Added value of this study: We retrospectively reviewed different types of anti-hypertensive drugs taken by COVID-19 patients with hypertension comorbidity prior to entering the hospital. We discovered that ARB hypertensive drugs were associated with a decreased risk of severe disease in elderly (age>65) COVID-19 patients (OR=0·343, 95% CI 0·128-0·916, p=0·025), the first evidence of ARBs association to COVID-19 infections in human. We conducted a meta-analysis in the literature and found that ARB has positive effects associated with morbidity and mortality of pneumonia. Implications of all the available evidence: ARB drugs are widely used in the population with hypertension. Treatments with ACEI and ARBs should be continuous according to medical guidelines. RCT trials of ARB associated with morbidity and mortality of SARS-CoV-2 infection are recommended in the future.