The potential role of COVID-19 in the induction of DNA damage

Long COVID as a disease of accelerated biological aging: An opportunity to translate geroscience interventions

It has been four years since long COVID-the protracted consequences that survivors of COVID-19 face-was first described. Yet, this entity continues to devastate the quality of life of an increasing number of COVID-19 survivors without any approved therapy and a paucity of clinical trials addressing its biological root causes. Notably, many of the symptoms of long COVID are typically seen with advancing age. Leveraging this similarity, we posit that Geroscience-which aims to target the biological drivers of aging to prevent age-associated conditions as a group-could offer promising therapeutic avenues for long COVID. Bearing this in mind, this review presents a translational framework for studying long COVID as a state of effectively accelerated biological aging, identifying research gaps and offering recommendations for future preclinical and clinical studies.

Towards understanding post-COVID-19 condition: A systematic meta-analysis of transcriptomic alterations with sex-specific insights

BACKGROUND

Post COVID-19 Condition (PCC), characterized by lingering symptoms post-acute COVID-19, poses clinical challenges, highlighting the need to understand its underlying molecular mechanisms. This meta-analysis aims to shed light on the transcriptomic landscapes and sex-specific molecular dynamics intrinsic to PCC.

METHODS

A systematic review identified three studies suitable for comprehensive meta-analysis, encompassing 135 samples (57 PCC subjects and 78 recovered subjects). We performed meta-analysis on differential gene expression, a gene set enrichment analysis of Reactome pathways, and weighted gene co-expression network analysis (WGCNA). We performed a drug and disease enrichment analysis and also assessed sex-specific differences in expression patterns.

KEY FINDINGS

A clear difference was observed in the transcriptomic profiles of PCC subjects, with 530 differentially expressed genes (DEGs) identified. Enrichment analysis revealed that the altered pathways were predominantly implicated in cell cycle processes, immune dysregulation and histone modifications. Antioxidant compounds such as hesperitin were predominantly linked to the hub genes of the DEGs. Sex-specific analyses highlighted disparities in DEGs and altered pathways in male and female PCC patients, revealing a difference in the expression of ribosomal proteins. PCC in men was mostly linked to neuro-cardiovascular disorders, while women exhibited more diverse disorders, with a high index of respiratory conditions.

CONCLUSION

Our study reveals the intricate molecular processes underlying PCC, highlighting that the differences in molecular dynamics between males and females could be key to understanding and effectively managing the varied symptomatology of this condition.

The cGAS-STING pathway in cardiovascular diseases: from basic research to clinical perspectives

The cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase-stimulator of interferon genes (cGAS-STING) signaling pathway, an important component of the innate immune system, is involved in the development of several diseases. Ectopic DNA-induced inflammatory responses are involved in several pathological processes. Repeated damage to tissues and metabolic organelles releases a large number of damage-associated molecular patterns (mitochondrial DNA, nuclear DNA, and exogenous DNA). The DNA fragments released into the cytoplasm are sensed by the sensor cGAS to initiate immune responses through the bridging protein STING. Many recent studies have revealed a regulatory role of the cGAS-STING signaling pathway in cardiovascular diseases (CVDs) such as myocardial infarction, heart failure, atherosclerosis, and aortic dissection/aneurysm. Furthermore, increasing evidence suggests that inhibiting the cGAS-STING signaling pathway can significantly inhibit myocardial hypertrophy and inflammatory cell infiltration. Therefore, this review is intended to identify risk factors for activating the cGAS-STING pathway to reduce risks and to simultaneously further elucidate the biological function of this pathway in the cardiovascular field, as well as its potential as a therapeutic target.

SARS-CoV-2, periodontal pathogens, and host factors: The trinity of oral post-acute sequelae of COVID-19

COVID-19 as a pan-epidemic is waning but there it is imperative to understand virus interaction with oral tissues and oral inflammatory diseases. We review periodontal disease (PD), a common inflammatory oral disease, as a driver of COVID-19 and oral post-acute-sequelae conditions (PASC). Oral PASC identifies with PD, loss of teeth, dysgeusia, xerostomia, sialolitis-sialolith, and mucositis. We contend that PD-associated oral microbial dysbiosis involving higher burden of periodontopathic bacteria provide an optimal microenvironment for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. These pathogens interact with oral epithelial cells activate molecular or biochemical pathways that promote viral adherence, entry, and persistence in the oral cavity. A repertoire of diverse molecules identifies this relationship including lipids, carbohydrates and enzymes. The S protein of SARS-CoV-2 binds to the ACE2 receptor and is activated by protease activity of host furin or TRMPSS2 that cleave S protein subunits to promote viral entry. However, PD pathogens provide additional enzymatic assistance mimicking furin and augment SARS-CoV-2 adherence by inducing viral entry receptors ACE2/TRMPSS, which are poorly expressed on oral epithelial cells. We discuss the mechanisms involving periodontopathogens and host factors that facilitate SARS-CoV-2 infection and immune resistance resulting in incomplete clearance and risk for 'long-haul' oral health issues characterising PASC. Finally, we suggest potential diagnostic markers and treatment avenues to mitigate oral PASC.

Beyond acute infection: molecular mechanisms underpinning cardiovascular complications in long COVID

SARS-CoV-2, responsible for the global COVID-19 pandemic, has manifested significant cardiovascular implications for the infected population. These cardiovascular repercussions not only linger beyond the initial phase of illness but have also been observed in individuals who remain asymptomatic. This extended and pervasive impact is often called the post-acute COVID-19 syndrome (PACS) or "Long COVID". With the number of confirmed global cases approaching an alarming 756 million, the multifaceted challenges of Long COVID are undeniable. These challenges span from individual health complications to considerable burdens on worldwide healthcare systems. Our review comprehensively examines the complications of the persistent cardiovascular complications associated with COVID-19. Furthermore, we shed light on emerging therapeutic strategies that promise to manage and possibly mitigate these complications. We also introduce and discuss the profound concerns regarding the potential transgenerational repercussions of SARS-CoV-2, emphasizing the need for a proactive and informed approach to future research and clinical practice.

Development of a novel machine learning model based on laboratory and imaging indices to predict acute cardiac injury in cancer patients with COVID-19 infection: a retrospective observational study

PURPOSE

Due to the increased risk of acute cardiac injury (ACI) and poor prognosis in cancer patients with COVID-19 infection, our aim was to develop a novel and interpretable model for predicting ACI occurrence in cancer patients with COVID-19 infection.

METHODS

This retrospective observational study screened 740 cancer patients with COVID-19 infection from December 2022 to April 2023. The least absolute shrinkage and selection operator (LASSO) regression was used for the preliminary screening of the indices. To enhance the model accuracy, we introduced an alpha index to further screen and rank the indices based on their significance. Random forest (RF) was used to construct the prediction model. The Shapley Additive Explanation (SHAP) and Local Interpretable Model-Agnostic Explanation (LIME) methods were utilized to explain the model.

RESULTS

According to the inclusion criteria, 201 cancer patients with COVID-19, including 36 variables indices, were included in the analysis. The top eight indices (albumin, lactate dehydrogenase, cystatin C, neutrophil count, creatine kinase isoenzyme, red blood cell distribution width, D-dimer and chest computed tomography) for predicting the occurrence of ACI in cancer patients with COVID-19 infection were included in the RF model. The model achieved an area under curve (AUC) of 0.940, an accuracy of 0.866, a sensitivity of 0.750 and a specificity of 0.900. The calibration curve and decision curve analysis showed good calibration and clinical practicability. SHAP results demonstrated that albumin was the most important index for predicting the occurrence of ACI. LIME results showed that the model could predict the probability of ACI in each cancer patient infected with COVID-19 individually.

CONCLUSION

We developed a novel machine-learning model that demonstrates high explainability and accuracy in predicting the occurrence of ACI in cancer patients with COVID-19 infection, using laboratory and imaging indices.

Age-related influence on DNA damage, proteomic inflammatory markers and oxidative stress in hospitalized COVID-19 patients compared to healthy controls

COVID-19 infections are accompanied by adverse changes in inflammatory pathways that are also partly influenced by increased oxidative stress and might result in elevated DNA damage. The aim of this case-control study was to examine whether COVID-19 patients show differences in oxidative stress-related markers, unconjugated bilirubin (UCB), an inflammation panel and DNA damage compared to healthy, age-and sex-matched controls. The Comet assay with and without the treatment of formamidopyrimidine DNA glycosylase (FPG) and H2O2 challenge was used to detect DNA damage in whole blood. qPCR was applied for gene expression, UCB was analyzed via HPLC, targeted proteomics were applied using Olink® inflammation panel and various oxidative stress as well as clinical biochemistry markers were analyzed in plasma. Hospitalized COVID-19 patients (n = 48) demonstrated higher serum levels of 55 inflammatory proteins (p < 0.001), including hs-C-reactive protein levels (p < 0.05), compared to healthy controls (n = 48). Interestingly, significantly increased age-related DNA damage (%-DNA in tail) after formamidopyrimidine DNA glycosylase (FPG) treatment was measured in younger (n = 24, average age 55.7 years; p < 0.05) but not in older COVID-19 patients (n = 24, average age 83.5 years; p > 0.05). Although various oxidative stress markers were not altered (e.g., FRAP, malondialdehyde, p > 0.05), a significant increased ratio of oxidized to reduced glutathione was detected in COVID-19 patients compared to healthy controls (p < 0.05). UCB levels were significantly lower in individuals with COVID-19, especially in younger COVID-19 patients (p < 0.05). These results suggest that COVID-19 infections exert effects on DNA damage related to age in hospitalized COVID-19 patients that might be driven by changes in inflammatory pathways but are not altered by oxidative stress parameters.

Plasma proteomics show altered inflammatory and mitochondrial proteins in patients with neurologic symptoms of post-acute sequelae of SARS-CoV-2 infection

Persistent symptoms of COVID-19 survivors constitute long COVID syndrome, also called post-acute sequelae of SARS-CoV-2 infection (PASC). Neurologic manifestations of PASC (Neuro-PASC) are particularly debilitating, long lasting, and poorly understood. To gain insight into the pathogenesis of PASC, we leveraged a well-characterized group of Neuro-PASC (NP) patients seen at our Neuro-COVID-19 clinic who had mild acute COVID-19 and never required hospitalization to investigate their plasma proteome. Using the SomaLogic platform, SomaScan, the plasma concentration of >7000 proteins was measured from 92 unvaccinated individuals, including 48 NP patients, 20 COVID-19 convalescents (CC) without lingering symptoms, and 24 unexposed healthy controls (HC) to interrogate underlying pathobiology and potential biomarkers of PASC. We analyzed the plasma proteome based on post-COVID-19 status, neurologic and non-neurologic symptoms, as well as subjective and objective standardized tests for changes in quality-of-life (QoL) and cognition associated with Neuro-PASC. The plasma proteome of NP patients differed from CC and HC subjects more substantially than post-COVID-19 groups (NP and CC combined) differed from HC. Proteomic differences in NP patients 3-9 months following acute COVID-19 showed alterations in inflammatory proteins and pathways relative to CC and HC subjects. Proteomic associations with Neuro-PASC symptoms of brain fog and fatigue included changes in markers of DNA repair, oxidative stress, and neutrophil degranulation. Furthermore, we discovered a correlation between NP patients lower subjective impression of recovery to pre-COVID-19 baseline with an increase in the concentration of the oxidative phosphorylation protein COX7A1, which was also associated with neurologic symptoms and fatigue, as well as impairment in QoL and cognitive dysfunction. Finally, we identified other oxidative phosphorylation-associated proteins correlating with central nervous system symptoms. Our results suggest ongoing inflammatory changes and mitochondrial involvement in Neuro-PASC and pave the way for biomarker validation for use in monitoring and development of therapeutic intervention for this debilitating condition.

SARS-CoV-2 and the DNA damage response

The recent coronavirus disease 2019 (COVID-19) pandemic was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 is characterized by respiratory distress, multiorgan dysfunction and, in some cases, death. The virus is also responsible for post-COVID-19 condition (commonly referred to as 'long COVID'). SARS-CoV-2 is a single-stranded, positive-sense RNA virus with a genome of approximately 30 kb, which encodes 26 proteins. It has been reported to affect multiple pathways in infected cells, resulting, in many cases, in the induction of a 'cytokine storm' and cellular senescence. Perhaps because it is an RNA virus, replicating largely in the cytoplasm, the effect of SARS-Cov-2 on genome stability and DNA damage responses (DDRs) has received relatively little attention. However, it is now becoming clear that the virus causes damage to cellular DNA, as shown by the presence of micronuclei, DNA repair foci and increased comet tails in infected cells. This review considers recent evidence indicating how SARS-CoV-2 causes genome instability, deregulates the cell cycle and targets specific components of DDR pathways. The significance of the virus's ability to cause cellular senescence is also considered, as are the implications of genome instability for patients suffering from long COVID.

Glutathione-related antioxidant defence, DNA damage, and DNA repair in patients suffering from post-COVID conditions

Post-COVID conditions are defined as the continuation of the symptoms of Coronavirus Disease 2019 (COVID-19) 3 months after the initial Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, with no other explanation. Post-COVID conditions are seen among 30%-60% of patients with asymptomatic or mild forms of COVID-19. The underlying pathophysiological mechanisms of post-COVID conditions are not known. In SARS-CoV-2 infection, activation of the immune system leads to increased production of reactive oxygen molecules, depleted antioxidant reserve, and finally occurrence of oxidative stress. In oxidative stress conditions, DNA damage increases and DNA repair systems impair. In this study, glutathione (GSH) level, glutathione peroxidase (GPx) activity, 8-hydroxydeoxyguanosine (8-OHdG) level, basal, induced, and post-repair DNA damage were investigated in individuals suffering from post-COVID conditions. In the red blood cells, GSH levels and GPx activities were measured with a spectrophotometric assay and a commercial kit. Basal, in vitro H2O2 (hydrogen peroxide)-induced, and post-repair DNA damage (DNA damage after a repair incubation following H2O2-treatment, in vitro) were determined in lymphocytes by the comet assay. The urinary 8-OHdG levels were measured by using a commercial ELISA kit. No significant difference was found between the patient and control groups for GSH level, GPx activity, and basal and H2O2-induced DNA damage. Post-repair DNA damage was found to be higher in the patient group than those in the control group. Urinary 8-OHdG level was lower in the patient group compared to the control group. In the control group, GSH level and post-repair DNA damage were higher in the vaccinated individuals. In conclusion, oxidative stress formed due to the immune response against SARS-COV-2 may impair DNA repair mechanisms. Defective DNA repair may be an underlying pathological mechanism of post-COVID conditions.

COVID-19-The Shift of Homeostasis into Oncopathology or Chronic Fibrosis in Terms of Female Reproductive System Involvement

The COVID-19 pandemic caused by the SARS-CoV-2 coronavirus remains a global public health concern due to the systemic nature of the infection and its long-term consequences, many of which remain to be elucidated. SARS-CoV-2 targets endothelial cells and blood vessels, altering the tissue microenvironment, its secretion, immune-cell subpopulations, the extracellular matrix, and the molecular composition and mechanical properties. The female reproductive system has high regenerative potential, but can accumulate damage, including due to SARS-CoV-2. COVID-19 is profibrotic and can change the tissue microenvironment toward an oncogenic niche. This makes COVID-19 and its consequences one of the potential regulators of a homeostasis shift toward oncopathology and fibrosis in the tissues of the female reproductive system. We are looking at SARS-CoV-2-induced changes at all levels in the female reproductive system.

Effects of COVID-19 Disease on DNA Damage, Oxidative Stress and Immune Responses

Coronavirus disease 2019 (COVID-19) has posed a great threat to public health and has caused concern due to its fatal consequences over the last few years. Most people with COVID-19 show mild-to-moderate symptoms and recover without the need for special treatment, while others become seriously ill and need medical attention. Additionally, some serious outcomes, such as heart attacks and even stroke, have been later reported in patients who had recovered. There are limited studies on how SARS-CoV-2 infection affects some molecular pathways, including oxidative stress and DNA damage. In this study, we aimed to evaluate DNA damage, using the alkaline comet assay, and its relationship with oxidative stress and immune response parameters in COVID-19-positive patients. Our results show that DNA damage, oxidative stress parameters and cytokine levels significantly increased in SARS-CoV-2-positive patients when compared with healthy controls. The effects of SARS-CoV-2 infection on DNA damage, oxidative stress and immune responses may be crucial in the pathophysiology of the disease. It is suggested that the illumination of these pathways will contribute to the development of clinical treatments and to reduce adverse effects in the future.

Causal effects of COVID-19 on cancer risk: A Mendelian randomization study

In contemporary literature, little attention has been paid to the association between coronavirus disease-2019 (COVID-19) and cancer risk. We performed the Mendelian randomization (MR) to investigate the causal associations between the three types of COVID-19 exposures (critically ill COVID-19, hospitalized COVID-19, and respiratory syndrome coronavirus 2 (SARS-CoV-2) infection) and 33 different types of cancers of the European population. The results of the inverse-variance-weighted model indicated that genetic liabilities to critically ill COVID-19 had suggestive causal associations with the increased risk for HER2-positive breast cancer (odds ratio [OR] = 1.0924; p-value = 0.0116), esophageal cancer (OR = 1.0004; p-value = 0.0226), colorectal cancer (OR = 1.0010; p-value = 0.0242), stomach cancer (OR = 1.2394; p-value = 0.0331), and colon cancer (OR = 1.0006; p-value = 0.0453). The genetic liabilities to hospitalized COVID-19 had suggestive causal associations with the increased risk for HER2-positive breast cancer (OR = 1.1096; p-value = 0.0458), esophageal cancer (OR = 1.0005; p-value = 0.0440) as well as stomach cancer (OR = 1.3043; p-value = 0.0476). The genetic liabilities to SARS-CoV-2 infection had suggestive causal associations with the increased risk for stomach cancer (OR = 2.8563; p-value = 0.0019) but with the decreasing risk for head and neck cancer (OR = 0.9986, p-value = 0.0426). The causal associations of the above combinations were robust through the test of heterogeneity and pleiotropy. Together, our study indicated that COVID-19 had causal effects on cancer risk.

Transcriptomic profiling of cardiac tissues from SARS-CoV-2 patients identifies DNA damage

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is known to present with pulmonary and extra-pulmonary organ complications. In comparison with the 2009 pandemic (pH1N1), SARS-CoV-2 infection is likely to lead to more severe disease, with multi-organ effects, including cardiovascular disease. SARS-CoV-2 has been associated with acute and long-term cardiovascular disease, but the molecular changes that govern this remain unknown. In this study, we investigated the host transcriptome landscape of cardiac tissues collected at rapid autopsy from seven SARS-CoV-2, two pH1N1, and six control patients using targeted spatial transcriptomics approaches. Although SARS-CoV-2 was not detected in cardiac tissue, host transcriptomics showed upregulation of genes associated with DNA damage and repair, heat shock, and M1-like macrophage infiltration in the cardiac tissues of COVID-19 patients. The DNA damage present in the SARS-CoV-2 patient samples, were further confirmed by γ-H2Ax immunohistochemistry. In comparison, pH1N1 showed upregulation of interferon-stimulated genes, in particular interferon and complement pathways, when compared with COVID-19 patients. These data demonstrate the emergence of distinct transcriptomic profiles in cardiac tissues of SARS-CoV-2 and pH1N1 influenza infection supporting the need for a greater understanding of the effects on extra-pulmonary organs, including the cardiovascular system of COVID-19 patients, to delineate the immunopathobiology of SARS-CoV-2 infection, and long term impact on health.

Investigation of inflammation, oxidative stress, and DNA damage in COVID-19 patients

COVID-19 disease, which spreads worldwide, is a disease characterized by widespread inflammation and affects many organs, especially the lungs. The resulting inflammation can lead to reactive oxygen radicals, leading to oxidative DNA damage. The pneumonia severity of 95 hospitalized patients with positive RT-PCR test was determined and divided into three groups: mild, moderate, and severe/critical. Inflammation markers (neutrophil-lymphocyte ratio, serum reactive protein, procalcitonin, etc.) were determined, and IL-10 and IFN-γ measurements were analyzed using the enzyme-linked immunosorbent assay method. In evaluating oxidative damage, total thiol, native thiol, disulfide, and ischemia-modified albumin (IMA) levels were determined by measuring spectrophotometrically. The comet assay method's percentage of tail DNA obtained was used to determine oxidative DNA damage. As a result, when the mild and severe/critical groups were compared, we found that total thiol, native thiol, and disulfide levels decreased significantly in the severe/critical group due to the increase in inflammation markers and cytokine levels (p < 0.05). We could not detect any significance in IMA levels between the groups (p > 0.05). At the same time, we determined an increase in the tail DNA percent level, that is, DNA damage, due to the increased oxidative effect. As a result, we determined that inflammation and oxidative stress increased in patients with severe pneumonia, and there was DNA damage in these patients.

The effect of DNA repair gene variants on COVID-19 disease: susceptibility, severity, and clinical course

Oxidative stress (OS), which leads to DNA damage, plays a role in the pathogenesis of Coronavirus disease 2019 (COVID-19). We aimed to evaluate the role of DNA repair gene variants [X-ray repair cross complementing 4 (XRCC4) rs28360071, rs6869366, and X-ray cross-complementary gene 1 (XRCC1) rs25487] in susceptibility to COVID-19 in a Turkish population. We also evaluated its effect on the clinical course of the disease. A total of 300 subjects, including 200 COVID-19 patients and 100 healthy controls, were included in this study. These variants were genotyped using polymerase chain reaction (PCR) and/or PCR-restriction fragment length polymorphism (RFLP) methods. The patients were divided into three groups: those with a mild or severe infection; those who died or lived at the 28-day follow-up; those who required inpatient treatment or intensive care. There were 87 women (43.5%) and 113 men (56.5%) in the patient group. Hypertension was the most common comorbidity (26%). In the patient group, XRCC4 rs6869366 G/G genotype and G allele frequency were increased compared to controls, while XRCC4 rs6869366 G/T and T/T genotype frequencies were found to be higher in controls compared to patients. For XRCC1 rs25487, the A/A and A/G genotypes were significantly associated with COVID-19 disease. All of the patients hospitalized in the intensive care unit had the XRCC4 rs6869366 G/G genotype. In this study, we evaluated for the first time the impact of DNA repair gene variants on COVID-19 susceptibility. Results suggested that XRCC4 rs6869366 and XRCC1 rs25487 were associated with COVID-19 suspectibility and clinical course.

DNA Repair Mechanisms are Activated in Circulating Lymphocytes of Hospitalized Covid-19 Patients

Purpose

Reactive oxygen species (ROS) are an important part of the inflammatory response during infection but can also promote DNA damage. Due to the sustained inflammation in severe Covid-19, we hypothesized that hospitalized Covid-19 patients would be characterized by increased levels of oxidative DNA damage and dysregulation of the DNA repair machinery.

Patients and Methods

Levels of the oxidative DNA lesion 8-oxoG and levels of base excision repair (BER) proteins were measured in peripheral blood mononuclear cells (PBMC) from patients (8-oxoG, n = 22; BER, n = 17) and healthy controls (n = 10) (Cohort 1). Gene expression related to DNA repair was investigated in two independent cohorts of hospitalized Covid-19 patients (Cohort 1; 15 patents and 5 controls, Cohort 2; 15 patients and 6 controls), and by publicly available datasets.

Results

Patients and healthy controls showed comparable amounts of oxidative DNA damage as assessed by 8-oxoG while levels of several BER proteins were increased in Covid-19 patients, indicating enhanced DNA repair in acute Covid-19 disease. Furthermore, gene expression analysis demonstrated regulation of genes involved in BER and double strand break repair (DSBR) in PBMC of Covid-19 patients and expression level of several DSBR genes correlated with the degree of respiratory failure. Finally, by re-analyzing publicly available data, we found that the pathway Hallmark DNA repair was significantly more regulated in circulating immune cells during Covid-19 compared to influenza virus infection, bacterial pneumonia or acute respiratory infection due to seasonal coronavirus.

Conclusion

Although beneficial by protecting against DNA damage, long-term activation of the DNA repair machinery could also contribute to persistent inflammation, potentially through mechanisms such as the induction of cellular senescence. However, further studies that also include measurements of additional markers of DNA damage are required to determine the role and precise molecular mechanisms for DNA repair in SARS-CoV-2 infection.