Targeted genetic analysis unveils novel associations between ACE I/D and APO T158C polymorphisms with D-dimer levels in severe COVID-19 patients with pulmonary embolism

Association between COVID-19 Infection or Vaccination Outcomes and Methylenetetrahydrofolate Reductase Gene Polymorphism: A Systematic Review of the Literature

BACKGROUND

Thrombosis is a detrimental sequala of COVID-19 infection; thus, prophylactic anti-coagulant therapy has been deemed mandatory in treatment unless serious contraindications are present. Susceptibility to thromboembolic events in COVID-19, or following COVID-19 vaccination, is likely attributable to an interplay of factors, including a patient's baseline clinical status and comorbidities, alongside genetic risk factors. In Europe, 8-20% of the population are homozygous for the MTHFR (methylene tetrahydrofolate reductase) variant, which compromises folate metabolism and elevates homocysteine levels. While heightened homocysteine levels are considered a risk factor for thromboembolic events, the precise clinical significance remains a contentious issue. However, recent research suggests elevated homocysteine levels may predict the course and severity of COVID-19 infection. Given the lack of reliable biomarkers predictive of COVID-19 thrombotic risk existing in practice, and the accessibility of MTHFR screening, we established two main outcomes for this study: (1) to determine the association between hereditary MTHFR mutations and COVID-19 severity and thromboembolic events and (2) to determine the link between MTHFR variants and adverse thrombotic events following COVID-19 vaccination.

METHODS

The review was conducted in accordance with PRISMA guidelines. Medline, Scopus, and Web of Science databases were searched from pandemic inception (11 March 2020) to 30 October 2023. Eligibility criteria were applied, and data extraction performed.

RESULTS

From 63 citations identified, a total of 14 articles met the full inclusion criteria (8 of which were cross-sectional or observational studies, and 6 were case studies or reports). Among the eight observational and cross-sectional studies evaluating the relationship between MTHFR variants (C667T; A1298C) and thromboembolic events in COVID-19 infection, four studies established a connection (n = 2200), while the remaining four studies failed to demonstrate any significant association (n = 38).

CONCLUSIONS

This systematic review demonstrated a possible association between the MTHFR gene variants and COVID-19 severity, thromboembolic events, and adverse events following vaccination. However, the paucity of robust data precluded any firm conclusions being drawn. Further prospective trials are required to determine the connection between the MTHFR gene variant and COVID-19 infection and vaccination outcomes.

An evidence-based debate on epigenetics and immunosenescence in COVID-19

Immunosenescence contributes to the decline of immune function leading to a reduced ability to respond to severe coronavirus disease 2019 (COVID-19) in elderly patients. Clinical course of COVID-19 is widely heterogeneous and guided by the possible interplay between genetic background and epigenetic-sensitive mechanisms underlying the immunosenescence which could explain, at least in part, the higher percentage of disease severity in elderly individuals. The most convincing evidence regards the hypomethylation of the angiotensin-converting enzyme 2 (ACE2) promoter gene in lungs as well as the citrullination of histone H3 in neutrophils which have been associated with worsening of COVID-19 outcome in elderly patients. In contrast, centenarians who have showed milder symptoms have been associated to a younger "epigenetic age" based on DNA methylation profiles at specific genomic sites (epigenetic clock). Some large prospective studies showed that the acceleration of epigenetic aging as well as the shortening of telomeres were significantly associated with lymphopenia and poor outcome suggesting prognostic biomarkers in elderly COVID-19 patients. Furthermore, randomized clinical trials showed that statins, L-arginine, and resveratrol could mediate anti-inflammatory effects via indirect epigenetic interference and might improve COVID-19 outcome. Here, we discuss the epigenetic-sensitive events which might contribute to increase the risk of severity and mortality in older subjects and possible targeted therapies to counteract immunosenescence.

Interrelationship between COVID-19 and Coagulopathy: Pathophysiological and Clinical Evidence

Since the first description of COVID-19 infection, among clinical manifestations of the disease, including fever, dyspnea, cough, and fatigue, it was observed a high incidence of thromboembolic events potentially evolving towards acute respiratory distress syndrome (ARDS) and COVID-19-associated-coagulopathy (CAC). The hypercoagulation state is based on an interaction between thrombosis and inflammation. The so-called CAC represents a key aspect in the genesis of organ damage from SARS-CoV-2. The prothrombotic status of COVID-19 can be explained by the increase in coagulation levels of D-dimer, lymphocytes, fibrinogen, interleukin 6 (IL-6), and prothrombin time. Several mechanisms have been hypothesized to explain this hypercoagulable process such as inflammatory cytokine storm, platelet activation, endothelial dysfunction, and stasis for a long time. The purpose of this narrative review is to provide an overview of the current knowledge on the pathogenic mechanisms of coagulopathy that may characterize COVID-19 infection and inform on new areas of research. New vascular therapeutic strategies are also reviewed.

The Impact of ACE Gene Variants on Acute-Phase Reactants in Children with Rheumatic Heart Disease

Rheumatic heart disease (RHD) is the most important sequela of upper respiratory group A Streptococcus (GAS) infection. The role of the common angiotensin-converting enzyme (ACE) insertion/deletion (I/D) variant in the disease and its subtypes remains uncertain. The acute-phase reactants (APRs) C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) form part of the Jones criteria for diagnosing RHD, and genetic factors are known to influence baseline CRP and ESR levels. Therefore, here, we investigated the relationship between the ACE I/D polymorphism and APR levels in RHD. A total of 268 individuals were recruited, including 123 RHD patients and 198 healthy controls. There was a trend toward a higher D allele frequency in RHD patients. The ACE I/D polymorphism genotype frequency and DD+ID allelic carriage were significantly associated with a high APR level (p = 0.04 and p = 0.02, respectively). These results highlight the importance of ACE I/D polymorphisms in RHD for disease stratification, but not for disease predisposition. Further studies in larger cohorts and different populations are now required to confirm this association and to explore the mechanism of this effect.