From February 1 to 14, 2020, clinical specimens, including serum, nasopharyngeal, and oropharyngeal swabs; urine; stool; and tissues from 73 hospitalized patients infected with SARS-CoV-2 were obtained in accordance with China Disease Control and Prevention guidelines and tested for SARS-CoV-2 RNA by using the Chinese Center for Disease Control and Prevention–standardized quantitative polymerase chain reaction assay.⁵ Li Q. et al. N Engl J Med. 2020; 382 : 1199-1207 Crossref PubMed Scopus (2941) Google Scholar Clinical characteristics of the 73 patients are shown in Supplementary Table 1. The esophageal, gastric, duodenal, and rectal tissues were obtained from 1 of the patients by using endoscopy. The patient’s clinical information is described in the Supplementary Case Clinical Information and Supplementary Table 2. Histologic staining (H&E) as well as viral receptor ACE2 and viral nucleocapsid staining were performed as described in the Supplementary Methods. The images of fluorescent staining were obtained by using laser scanning confocal microscopy (LSM880, Carl Zeiss MicroImaging, Oberkochen, Germany) and are shown in Figure 1. This study was approved by the Ethics Committee of The Fifth Affiliated Hospital, Sun Yat-sen University, and all patients signed informed consent forms. Figure 1 Images of histologic and immunofluorescent staining of gastrointestinal tissues. Shown are images of histologic and immunofluorescent staining of esophagus, stomach, duodenum, and rectum. The scale bar in the histologic image represents 100 μm. The scale bar in the immunofluorescent image represents 20 μm. View Large Image Figure Viewer Download Hi-res image Download (PPT)

Objective To study the GI symptoms in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected patients. Design We analysed epidemiological, demographic, clinical and laboratory data of 95 cases with SARS-CoV-2 caused coronavirus disease 2019. Real-time reverse transcriptase PCR was used to detect the presence of SARS-CoV-2 in faeces and GI tissues. Results Among the 95 patients, 58 cases exhibited GI symptoms of which 11 (11.6%) occurred on admission and 47 (49.5%) developed during hospitalisation. Diarrhoea (24.2%), anorexia (17.9%) and nausea (17.9%) were the main symptoms with five (5.3%), five (5.3%) and three (3.2%) cases occurred on the illness onset, respectively. A substantial proportion of patients developed diarrhoea during hospitalisation, potentially aggravated by various drugs including antibiotics. Faecal samples of 65 hospitalised patients were tested for the presence of SARS-CoV-2, including 42 with and 23 without GI symptoms, of which 22 (52.4%) and 9 (39.1%) were positive, respectively. Six patients with GI symptoms were subjected to endoscopy, revealing oesophageal bleeding with erosions and ulcers in one severe patient. SARS-CoV-2 RNA was detected in oesophagus, stomach, duodenum and rectum specimens for both two severe patients. In contrast, only duodenum was positive in one of the four non-severe patients. Conclusions GI tract may be a potential transmission route and target organ of SARS-CoV-2.

Copper is an essential trace element for the human body, and its requirement for optimistic immune functions has been recognized for decades. How copper is involved in the innate immune pathway, however, remains to be clarified. Here, we report that copper serves as a signal molecule to regulate the kinase activity of alpha-kinase 1 (ALPK1), a cytosolic pattern-recognition receptor (PRR), and therefore promotes host cell defense against bacterial infection. We show that in response to infection, host cells actively accumulate copper in the cytosol, and the accumulated cytosolic copper enhances host cell defense against evading pathogens, including intracellular and, unexpectedly, extracellular bacteria. Subsequently, we demonstrate that copper activates the innate immune pathway of host cells in an ALPK1-dependent manner. Further mechanistic studies reveal that copper binds to ALPK1 directly and is essential for the kinase activity of this cytosolic PRR. Moreover, the binding of copper to ALPK1 enhances the sensitivity of ALPK1 to the bacterial metabolite ADP-heptose and eventually prompts host cells to elicit an enhanced immune response during bacterial infection. Finally, using a zebrafish in vivo model, we show that a copper-treated host shows an increased production of proinflammatory cytokines, enhanced recruitment of phagosome cells, and promoted bacterial clearance. Our findings uncover a previously unrecognized role of copper in the modulation of host innate immune response against bacterial pathogens and advance our knowledge on the cross talk between cytosolic copper homeostasis and immune system.

Severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) can cause gastrointestinal (GI) symptoms that often correlate with the severity of COVID‐19. Here, we explored the pathogenesis underlying the intestinal inflammation in COVID‐19. Plasma VEGF level was particularly elevated in patients with GI symptoms and significantly correlated with intestinal edema and disease progression. Through an animal model mimicking intestinal inflammation upon stimulation with SARS‐CoV‐2 spike protein, we further revealed that VEGF was over‐produced in the duodenum prior to its ascent in the circulation. Mechanistically, SARS‐CoV‐2 spike promoted VEGF production through activating the Ras‐Raf‐MEK‐ERK signaling in enterocytes, but not in endothelium, and inducing permeability and inflammation. Blockage of the ERK/VEGF axis was able to rescue vascular permeability and alleviate intestinal inflammation in vivo . These findings provide a mechanistic explanation and therapeutic targets for the GI symptoms of COVID‐19.

The new coronavirus (SARS-CoV-2) outbreak originating from Wuhan, China, poses a threat to global health. While it’s evident that the virus invades respiratory tract and transmits from human to human through airway, other viral tropisms and transmission routes remain unknown. We tested viral RNA in stool from 73 SARS-CoV-2-infected hospitalized patients using rRT-PCR. 53.42% of the patients tested positive in stool. 23.29% of the patients remained positive in feces even after the viral RNA decreased to undetectable level in respiratory tract. The viral RNA was also detected in gastrointestinal tissues. Furthermore, gastric, duodenal and rectal epithelia showed positive immunofluorescent staining of viral host receptor ACE2 and viral nucleocapsid protein in a case of SARS-CoV-2 infection. Our results provide evidence for gastrointestinal infection of SARS-CoV-2, highlighting its potential fecal-oral transmission route.