COVID-19 Metabolomic-Guided Amino Acid Therapy Protects from Inflammation and Disease Sequelae.

The outbreak of coronavirus disease 2019 (COVID-19) has caused a worldwide pandemic since 2019. A metabolic disorder is a contributing factor to deaths from COVID-19. However, the underlying mechanism of metabolic dysfunction in COVID-19 patients and the potential interventions are not elucidated. Here targeted plasma metabolomic is performed, and the metabolite profiles among healthy controls, and asymptomatic, moderate, and severe COVID-19 patients are compared. Among the altered metabolites, arachidonic acid and linolenic acid pathway metabolites are profoundly up-regulated in COVID-19 patients. Arginine biosynthesis, alanine, aspartate, and glutamate metabolism pathways are significantly disturbed in asymptomatic patients. In the comparison of metabolite variances among the groups, higher levels of l-citrulline and l-glutamine are found in asymptomatic carriers and moderate or severe patients at the remission stage. Furthermore, l-citrulline and l-glutamine combination therapy is demonstrated to effectively protect mice from coronavirus infection and endotoxin-induced sepsis, and is observed to efficiently prevent the occurrence of pulmonary fibrosis and central nervous system damage. Collectively, the data reveal the metabolite profile of asymptomatic COVID-19 patients and propose a potential strategy for COVID-19 treatment.

TREM-2 is a sensor and activator of T cell response in SARS-CoV-2 infection.

Limited understanding of T cell responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has impeded vaccine development and drug discovery for coronavirus disease 2019 (COVID-19). We found that triggering receptor expressed on myeloid cells 2 (TREM-2) was induced in T cells in the blood and lungs of patients with COVID-19. After binding to SARS-CoV-2 membrane (M) protein through its immunoglobulin domain, TREM-2 then activated the CD3ζ/ZAP70 complex, leading to STAT1 phosphorylation and T-bet transcription. In vitro stimulation with M protein-reconstituted pseudovirus or recombinant M protein, and TREM-2 promoted the T helper cell 1 (TH1) cytokines interferon-γ and tumor necrosis factor. In vivo infection of CD4­TREM-2 conditional knockout mice with murine coronavirus mouse hepatitis virus A-59 showed that intrinsic TREM-2 in T cells enhanced TH1 response and viral clearance, thus aggravating lung destruction. These findings demonstrate a previously unidentified role for TREM-2 in SARS-CoV-2 infection, and suggest potential strategies for drug discovery and clinical management of COVID-19.

Altered oral and gut microbiota and its association with SARS-CoV-2 viral load in COVID-19 patients during hospitalization.

The human oral and gut commensal microbes play vital roles in the development and maintenance of immune homeostasis, while its association with susceptibility and severity of SARS-CoV-2 infection is barely understood. In this study, we investigated the dynamics of the oral and intestinal flora before and after the clearance of SARS-CoV-2 in 53 COVID-19 patients, and then examined their microbiome alterations in comparison to 76 healthy individuals. A total of 140 throat swab samples and 81 fecal samples from these COVID-19 patients during hospitalization, and 44 throat swab samples and 32 fecal samples from sex and age-matched healthy individuals were collected and then subjected to 16S rRNA sequencing and viral load inspection. We found that SARS-CoV-2 infection was associated with alterations of the microbiome community in patients as indicated by both alpha and beta diversity indexes. Several bacterial taxa were identified related to SARS-CoV-2 infection, wherein elevated Granulicatella and Rothia mucilaginosa were found in both oral and gut microbiome. The SARS-CoV-2 viral load in those samples was also calculated to identify potential dynamics between COVID-19 and the microbiome. These findings provide a meaningful baseline for microbes in the digestive tract of COVID-19 patients and will shed light on new dimensions for disease pathophysiology, potential microbial biomarkers, and treatment strategies for COVID-19.