ACE2 Protein Expression During Childhood, Adolescence, and Early Adulthood

COVID-19 and Long COVID: Disruption of the Neurovascular Unit, Blood-Brain Barrier, and Tight Junctions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), could affect brain structure and function. SARS-CoV-2 can enter the brain through different routes, including the olfactory, trigeminal, and vagus nerves, and through blood and immunocytes. SARS-CoV-2 may also enter the brain from the peripheral blood through a disrupted blood-brain barrier (BBB). The neurovascular unit in the brain, composed of neurons, astrocytes, endothelial cells, and pericytes, protects brain parenchyma by regulating the entry of substances from the blood. The endothelial cells, pericytes, and astrocytes highly express angiotensin converting enzyme 2 (ACE2), indicating that the BBB can be disturbed by SARS-CoV-2 and lead to derangements of tight junction and adherens junction proteins. This leads to increased BBB permeability, leakage of blood components, and movement of immune cells into the brain parenchyma. SARS-CoV-2 may also cross microvascular endothelial cells through an ACE2 receptor-associated pathway. The exact mechanism of BBB dysregulation in COVID-19/neuro-COVID is not clearly known, nor is the development of long COVID. Various blood biomarkers could indicate disease severity and neurologic complications in COVID-19 and help objectively diagnose those developing long COVID. This review highlights the importance of neurovascular and BBB disruption, as well as some potentially useful biomarkers in COVID-19, and long COVID/neuro-COVID.

Coronavirus disease 2019 and gastrointestinal disorders in children

During the past 3 years, the coronavirus disease 2019 (COVID-19) pandemic has had a great impact on people all over the world. However, it has become evident that disease manifestations and severity differ across age groups. Most children have a milder disease course than adults but possibly more pronounced gastrointestinal (GI) symptoms. Given the child's developing immune system, the impact of COVID-19 on disease development may differ compared to adults. This study reviews the potential bi-directional relationship between COVID-19 and GI diseases in children, focusing on common pediatric conditions such as functional GI disorders (FGID), celiac disease (CeD), and inflammatory bowel disease (IBD). Children with GI diseases, in general, and CeD and IBD, in particular, do not seem to have an increased risk of severe COVID-19, including risks of hospitalization, critical care need, and death. While infections are considered candidate environmental factors in both CeD and IBD pathogenesis, and specific infectious agents are known triggers for FGID, there is still not sufficient evidence to implicate COVID-19 in the development of either of these diseases. However, given the scarcity of data and the possible latency period between environmental triggers and disease development, future investigations in this field are warranted.

A novel plant-made monoclonal antibody enhances the synergetic potency of an antibody cocktail against the SARS-CoV-2 Omicron variant

This study describes a novel, neutralizing monoclonal antibody (mAb), 11D7, discovered by mouse immunization and hybridoma generation, against the parental Wuhan-Hu-1 RBD of SARS-CoV-2. We further developed this mAb into a chimeric human IgG and recombinantly expressed it in plants to produce a mAb with human-like, highly homogenous N-linked glycans that has potential to impart greater potency and safety as a therapeutic. The epitope of 11D7 was mapped by competitive binding with well-characterized mAbs, suggesting that it is a Class 4 RBD-binding mAb that binds to the RBD outside the ACE2 binding site. Of note, 11D7 maintains recognition against the B.1.1.529 (Omicron) RBD, as well neutralizing activity. We also provide evidence that this novel mAb may be useful in providing additional synergy to established antibody cocktails, such as Evusheld™ containing the antibodies tixagevimab and cilgavimab, against the Omicron variant. Taken together, 11D7 is a unique mAb that neutralizes SARS-CoV-2 through a mechanism that is not typical among developed therapeutic mAbs and by being produced in ΔXFT Nicotiana benthamiana plants, highlights the potential of plants to be an economic and safety-friendly alternative platform for generating mAbs to address the evolving SARS-CoV-2 crisis.

Smoking modulates different secretory subpopulations expressing SARS-CoV-2 entry genes in the nasal and bronchial airways

SARS-CoV-2 infection and disease severity are influenced by viral entry (VE) gene expression patterns in the airway epithelium. The similarities and differences of VE gene expression (ACE2, TMPRSS2, and CTSL) across nasal and bronchial compartments have not been fully characterized using matched samples from large cohorts. Gene expression data from 793 nasal and 1673 bronchial brushes obtained from individuals participating in lung cancer screening or diagnostic workup revealed that smoking status (current versus former) was the only clinical factor significantly and reproducibly associated with VE gene expression. The expression of ACE2 and TMPRSS2 was higher in smokers in the bronchus but not in the nose. scRNA-seq of nasal brushings indicated that ACE2 co-expressed genes were highly expressed in club and C15orf48+ secretory cells while TMPRSS2 co-expressed genes were highly expressed in keratinizing epithelial cells. In contrast, these ACE2 and TMPRSS2 modules were highly expressed in goblet cells in scRNA-seq from bronchial brushings. Cell-type deconvolution of the gene expression data confirmed that smoking increased the abundance of several secretory cell populations in the bronchus, but only goblet cells in the nose. The association of ACE2 and TMPRSS2 with smoking in the bronchus is due to their high expression in goblet cells which increase in abundance in current smoker airways. In contrast, in the nose, these genes are not predominantly expressed in cell populations modulated by smoking. In individuals with elevated lung cancer risk, smoking-induced VE gene expression changes in the nose likely have minimal impact on SARS-CoV-2 infection, but in the bronchus, smoking may lead to higher viral loads and more severe disease.

Diabetes and SARS-CoV-2–Is There a Mutual Connection?

SARS-CoV-2, a newly emerged virus described for the first time in late 2019, affects multiple organs in humans, including the pancreas. Here, we present the bilateral link between the pathophysiology of diabetes and COVID-19, with diabetes being COVID-19 comorbidity, and a complication of SARS-CoV-2 infection. Analysis of clinical data indicates that patients with chronic conditions like diabetes are at increased risk of severe COVID-19, hospitalization, ICU admission, and death compared to the healthy subjects. Further, we show that SARS-CoV-2 infection might be also associated with the development of new-onset diabetes and diabetic ketoacidosis. We then discuss the options for studying SARS-CoV-2 infection in pancreatic settings, including the use of human pluripotent stem cell-derived pancreatic organoids. Further, we review the presence of SARS-CoV-2 receptors in different pancreatic cell types and the infection efficiency based on pancreatic sections from COVID-19 patients and primary human islet in vitro studies. Finally, we discuss the impact of SARS-CoV-2 infection on human pancreatic cell homeostasis, focusing on β-cells.