ABSTRACT
BACKGROUND & AIMS: Gastrointestinal (GI) manifestations have been increasingly reported in patients with coronavirus disease 2019 (COVID-19). However, the roles of the GI tract in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are not fully understood. We investigated how the GI tract is involved in SARS-CoV-2 infection to elucidate the pathogenesis of COVID-19. METHODS: Our previously established nonhuman primate (NHP) model of COVID-19 was modified in this study to test our hypothesis. Rhesus monkeys were infected with an intragastric or intranasal challenge with SARS-CoV-2. Clinical signs were recorded after infection. Viral genomic RNA was quantified by quantitative reverse transcription polymerase chain reaction. Host responses to SARS-CoV-2 infection were evaluated by examining inflammatory cytokines, macrophages, histopathology, and mucin barrier integrity. RESULTS: Intranasal inoculation with SARS-CoV-2 led to infections and pathologic changes not only in respiratory tissues but also in digestive tissues. Expectedly, intragastric inoculation with SARS-CoV-2 resulted in the productive infection of digestive tissues and inflammation in both the lung and digestive tissues. Inflammatory cytokines were induced by both types of inoculation with SARS-CoV-2, consistent with the increased expression of CD68. Immunohistochemistry and Alcian blue/periodic acid-Schiff staining showed decreased Ki67, increased cleaved caspase 3, and decreased numbers of mucin-containing goblet cells, suggesting that the inflammation induced by these 2 types of inoculation with SARS-CoV-2 impaired the GI barrier and caused severe infections. CONCLUSIONS: Both intranasal and intragastric inoculation with SARS-CoV-2 caused pneumonia and GI dysfunction in our rhesus monkey model. Inflammatory cytokines are possible connections for the pathogenesis of SARS-CoV-2 between the respiratory and digestive systems.
Subject(s)
COVID-19/transmission , Gastroenteritis/pathology , Gastrointestinal Tract/pathology , Lung/pathology , Animals , Bronchi/metabolism , Bronchi/pathology , COVID-19/immunology , COVID-19/metabolism , COVID-19/pathology , COVID-19 Nucleic Acid Testing , Caspase 3/metabolism , Cytokines/immunology , Disease Models, Animal , Gastric Mucosa , Gastroenteritis/metabolism , Gastroenteritis/virology , Gastrointestinal Tract/immunology , Gastrointestinal Tract/metabolism , Goblet Cells/pathology , Intestine, Small/metabolism , Intestine, Small/pathology , Ki-67 Antigen/metabolism , Lung/diagnostic imaging , Lung/immunology , Lung/metabolism , Macaca mulatta , Nasal Mucosa , RNA, Viral/isolation & purification , Random Allocation , Rectum/metabolism , Rectum/pathology , SARS-CoV-2 , Trachea/metabolism , Trachea/pathologyABSTRACT
COVID-19 dramatically affects the elderly. Due to the large usage of antibiotics during the current pandemic and the gastrointestinal manifestations of COVID-19, the elderly population, hospitalized patients, residents in LTCFs and persons that survived the COVID-19 might be more prone to Clostridioides difficile infections (CDI). A renewed attention to CDI is necessary during the ongoing COVID-19 pandemic.