DPP9 as a Potential Novel Mediator in Gastrointestinal Virus Infection.

Dipeptidyl peptidase 9 (DPP9) is a member of the dipeptidyl peptidase IV family. Inhibition of DPP9 has recently been shown to activate the nucleotide-binding domain leucine-rich repeat 1 (NLRP1) inflammasome. NLRP1 is known to bind nucleic acids with high affinity and directly interact with double stranded RNA, which plays a key role in viral replication. DPP9 has also recently emerged as a key gene related to lung-inflammation in critical SARS-CoV-2 infection. Importantly, DPP9 activity is strongly dependent on the oxidative status. Here, we explored the potential role of DPP9 in the gastrointestinal tract. We performed transcriptomics analyses of colon (microarray, n = 37) and jejunal (RNA sequencing, n = 31) biopsies from two independent cohorts as well as plasma metabolomics analyses in two independent cohorts (n = 37 and n = 795). The expression of DPP9 in the jejunum, colon, and blood was significantly associated with circulating biomarkers of oxidative stress (uric acid, bilirubin). It was also associated positively with the expression of transcription factors (NRF-2) and genes (SOD, CAT, GPX) encoding for antioxidant enzymes, but negatively with that of genes (XDH, NOX) and transcription factors (NF-KB) involved in ROS-generating enzymes. Gene co-expression patterns associated with DPP9 identified several genes participating in antiviral pathways in both tissues. Notably, DPP9 expression in the colon and plasma was strongly positively associated with several circulating nucleotide catabolites (hypoxanthine, uric acid, 3-ureidopropionic acid) with important roles in the generation of ROS and viral infection, as well as other metabolites related to oxidative stress (Resolvin D1, glutamate-containing dipeptides). Gene-drug enrichment analyses identified artenimol, puromycin, anisomycin, 3-phenyllactic acid, and linezolid as the most promising drugs targeting these DPP9-associated genes. We have identified a novel potential pathogenic mechanism of viral infection in the digestive tract and promising existing drugs that can be repositioned against viral infection.

Lipidomics and metabolomics signatures of SARS-CoV-2 mediators/receptors in peripheral leukocytes, jejunum and colon.

Cell surface receptor-mediated viral entry plays a critical role in this infection. Well-established SARS-CoV-2 receptors such as ACE2 and TMPRSS2 are highly expressed in the gastrointestinal tract. In fact, there are evidences that SARS-CoV-2 infects epithelial cells from the digestive system. However, emerging research has identified novel mediators such as DPP9, TYK2, and CCR2, all playing a critical role in inflammation. We evaluated the expression of SARS-CoV-2 receptors in peripheral leukocytes (n = 469), jejunum (n = 30), and colon (n = 37) of three independent cohorts by real-time PCR, RNA-sequencing, and microarray transcriptomics. We also performed HPCL-MS/MS lipidomics and metabolomics analyses to identify signatures linked to SARS-CoV-2 receptors. We found markedly higher peripheral leukocytes ACE2 expression levels in women compared to men, whereas the intestinal expression of TMPRSS2 was positively associated with BMI. Consistent lipidomics signatures associated with the expression of these mediators were found in both tissues and peripheral leukocytes involving n-3 long-chain PUFAs and arachidonic acid-derived eicosanoids, which play a key role in the regulation of inflammation and may interfere with viral entry and replication. Medium- and long-chain hydroxy acids, which have shown to interfere in viral replication, were also liked to SARS-CoV2 receptors. Gonadal steroids were also associated with the expression of some of these receptors, even after controlling for sex. The expression of SARS-CoV2 receptors was associated with several metabolic and nutritional traits in different cell types. This information may be useful in the design of potential therapies targeted at coronavirus entry.

Lipidomics and metabolomics signatures of SARS-CoV-2 mediators/receptors in peripheral leukocytes, jejunum and colon

Graphical abstract Cell surface receptor-mediated viral entry plays a critical role in this infection. Well-established SARS-CoV-2 receptors such as ACE2 and TMPRSS2 are highly expressed in the gastrointestinal tract. In fact, there are evidences that SARS-CoV-2 infects epithelial cells from the digestive system. However, emerging research has identified novel mediators such as DPP9, TYK2, and CCR2, all playing a critical role in inflammation. We evaluated the expression of SARS-CoV-2 receptors in peripheral leukocytes (n=469), jejunum (n=30), and colon (n=37) of three independent cohorts by real-time PCR, RNA-sequencing, and microarray transcriptomics. We also performed HPCL-MS/MS lipidomics and metabolomics analyses to identify signatures linked to SARS-CoV-2 receptors. We found markedly higher peripheral leukocytes ACE2 expression levels in women compared to men, whereas the intestinal expression of TMPRSS2 was positively associated with BMI. Consistent lipidomics signatures associated with the expression of these mediators were found in both tissues and peripheral leukocytes involving n-3 long-chain PUFAs and arachidonic acid-derived eicosanoids, which play a key role in the regulation of inflammation and may interfere with viral entry and replication. Medium- and long-chain hydroxy acids, which have shown to interfere in viral replication, were also liked to SARS-CoV2 receptors. Gonadal steroids were also associated with the expression of some of these receptors, even after controlling for sex. The expression of SARS-CoV2 receptors was associated with several metabolic and nutritional traits in different cell types. This information may be useful in the design of potential therapies targeted at coronavirus entry.

Vascular Endothelial Damage in the Pathogenesis of Organ Injury in Severe COVID-19.

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Human Aortic Valve Interstitial Cells Display Proangiogenic Properties During Calcific Aortic Valve Disease.

OBJECTIVE: The study's aim was to analyze the capacity of human valve interstitial cells (VICs) to participate in aortic valve angiogenesis. Approach and Results: VICs were isolated from human aortic valves obtained after surgery for calcific aortic valve disease and from normal aortic valves unsuitable for grafting (control VICs). We examined VIC in vitro and in vivo potential to differentiate in endothelial and perivascular lineages. VIC paracrine effect was also examined on human endothelial colony-forming cells. A pathological VIC (VICp) mesenchymal-like phenotype was confirmed by CD90+/CD73+/CD44+ expression and multipotent-like differentiation ability. When VICp were cocultured with endothelial colony-forming cells, they formed microvessels by differentiating into perivascular cells both in vivo and in vitro. VICp and control VIC conditioned media were compared using serial ELISA regarding quantification of endothelial and angiogenic factors. Higher expression of VEGF (vascular endothelial growth factor)-A was observed at the protein level in VICp-conditioned media and confirmed at the mRNA level in VICp compared with control VIC. Conditioned media from VICp induced in vitro a significant increase in endothelial colony-forming cell proliferation, migration, and sprouting compared with conditioned media from control VIC. These effects were inhibited by blocking VEGF-A with blocking antibody or siRNA approach, confirming VICp involvement in angiogenesis by a VEGF-A dependent mechanism. CONCLUSIONS: We provide here the first proof of an angiogenic potential of human VICs isolated from patients with calcific aortic valve disease. These results point to a novel function of VICp in valve vascularization during calcific aortic valve disease, with a perivascular differentiation ability and a VEGF-A paracrine effect. Targeting perivascular differentiation and VEGF-A to slow calcific aortic valve disease progression warrants further investigation.