Abstract
BACKGROUND AND AIMS
ACE2, part of the counter-regulatory arm of the renin–angiotensin system, serves both as protective toward oxidative stress and cardiovascular remodeling and as a key ...entry for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). ACE2 has two isoforms, non-glycosylated and glycosylated, the latter being accountable for the binding with SARS-CoV-2. After the binding, viruses use proteases as cathepsin-L (Cat-L) to entry the cells. Both ACE2 glycosylation and Cat-L activity are pH-dependent. Gitelman and Bartter syndromes (GS/BS), rare genetic tubulopathies, are characterized by electrolytic alterations, activation of the renin–angiotensin system, yet normo-hypotension, increased levels of ACE2 and metabolic alkalosis with likely increased intracellular pH. We reported that during the first wave of COVID-19 in early 2020 none of our cohort of 128 GS/BS patients from the major hotspots in Northern Italy had been infected or suffered any major COVID-19 symptoms and in a second survey on the same cohort in 2021, we reported only eight positives, four asymptomatic and four with very light symptoms This study aims to investigate potential mechanisms as ACE2 glycosylation and Cat-L activity related to patients’ metabolic alkalosis and viral entry/infection.
METHOD
Mononuclear cells ACE2 glycosylation (Western blot) and blood Cat-L activity (ELISA) from 20 GS/BS patients have been compared with those from 15 healthy subjects.
RESULTS
Non-glycosylated ACE2 was higher in GS/BS (0.82 ± 0.19 d.u. versus 0.67 ± 0.13, P = 0.01); glycosylated ACE2 was not different (0.85 ± 0.28 in GS/BS versus 0.73 ± 0.23, P = 0.19). Cat-L activity was lower in GS/BS (3.90 ± 1.13 r.f.u. versus 5.31 ± 0.8, P <0 0.001) and inversely correlated with blood bicarbonate (HCO3−), while a negative correlation between glycosylated ACE2 and HCO3− approaches statistical significance (P = 0.08).
CONCLUSION
GS/BS's metabolic alkalosis, likely by increasing intracellular pH, influences the glycosylation of ACE2 and the activity of Cat-L, providing a mechanistic explanation for the near-complete absence of COVID-19 or its symptoms reported in our cohort. These findings provide a rationale for pursuing the identification and/or synthesis of new drugs that specifically target ACE2 glycosylation and/or proteases involved in SARS-CoV-2 infection.
Mesenchymal tumours represent one of the most challenging field of diagnostic pathology and refinement of classification schemes plays a key role in improving the quality of pathologic diagnosis and, ...as a consequence, of therapeutic options. The recent publication of the new WHO classification of Soft Tissue Tumours and Bone represents a major step toward improved standardization of diagnosis. Importantly, the 2020 WHO classification has been opened to expert clinicians that have further contributed to underline the key value of pathologic diagnosis as a rationale for proper treatment. Several relevant advances have been introduced. In the attempt to improve the prediction of clinical behaviour of solitary fibrous tumour, a risk assessment scheme has been implemented. NTRK-rearranged soft tissue tumours are now listed as an “emerging entity” also in consideration of the recent therapeutic developments in terms of NTRK inhibition. This decision has been source of a passionate debate regarding the definition of “tumour entity” as well as the consequences of a “pathology agnostic” approach to precision oncology. In consideration of their distinct clinicopathologic features, undifferentiated round cell sarcomas are now kept separate from Ewing sarcoma and subclassified, according to the underlying gene rearrangements, into three main subgroups (CIC, BCLR and not ETS fused sarcomas) Importantly, In order to avoid potential confusion, tumour entities such as gastrointestinal stroma tumours are addressed homogenously across the different WHO fascicles. Pathologic diagnosis represents the integration of morphologic, immunohistochemical and molecular characteristics and is a key element of clinical decision making. The WHO classification is as a key instrument to promote multidisciplinarity, stimulating pathologists, geneticists and clinicians to join efforts aimed to translate novel pathologic findings into more effective treatments.
The vast non-coding portion of the human genome is full of functional elements and disease-causing regulatory variants. The principles defining the relationships between these elements and distal ...target genes remain unknown. Promoters and distal elements can engage in looping interactions that have been implicated in gene regulation. Here we have applied chromosome conformation capture carbon copy (5C) to interrogate comprehensively interactions between transcription start sites (TSSs) and distal elements in 1% of the human genome representing the ENCODE pilot project regions. 5C maps were generated for GM12878, K562 and HeLa-S3 cells and results were integrated with data from the ENCODE consortium. In each cell line we discovered >1,000 long-range interactions between promoters and distal sites that include elements resembling enhancers, promoters and CTCF-bound sites. We observed significant correlations between gene expression, promoter-enhancer interactions and the presence of enhancer RNAs. Long-range interactions show marked asymmetry with a bias for interactions with elements located ∼120 kilobases upstream of the TSS. Long-range interactions are often not blocked by sites bound by CTCF and cohesin, indicating that many of these sites do not demarcate physically insulated gene domains. Furthermore, only ∼7% of looping interactions are with the nearest gene, indicating that genomic proximity is not a simple predictor for long-range interactions. Finally, promoters and distal elements are engaged in multiple long-range interactions to form complex networks. Our results start to place genes and regulatory elements in three-dimensional context, revealing their functional relationships.
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