RELATIVE TELOMERE LENGTH IMPACT ON MORTALITY OF COVID-19: SEX DIFFERENCES.

INTRODUCTION: Increasing age is associated with severity and higher mortality of COVID-19. Telomere shortening is associated with higher risk of infections and may be used to identify those patients who are more likely to die. We evaluated the association between relative telomere length (RTL) and COVID-19 mortality. METHODS: RTL was measured in patients hospitalized because of COVID-19. We used Kaplan-Meier method to analyze survival probabilities, and Cox regression to investigate the association between RTL and mortality (30 and 90 days). RESULTS: 608 patients were included in the analysis (mean age =72.5 years, 41.1% women, and 53.8% Caucasic). During the study period, 75 people died from COVID-19 and 533 survived. Lower RTL was associated with a higher risk of death in women either at 30 (adjusted HR (aHR)=3.33; 95%CI=1.05-10.00; p=0.040) and at 90 days (aHR=3.57; 95%CI=1.23-11.11; p=0.019). CONCLUSION: Lower RTL was associated with a higher risk of dying of COVID-19 in women. This finding suggests that RTL has an essential role in the prognosis of this subset of the population. This article is protected by copyright. All rights reserved.

Age-related changes in the immune system and the consequences of immunosenescence

The cellular and molecular hallmarks of aging include genomic instability, telomere attrition, epigenetic alterations, changes in intracellular signaling, cellular senescence, and mitochondrial dysfunction. These lead to complex remodeling and changes involving both the innate and adaptive immune systems. Besides age related changes in immune cells, the microenvironment in the lymphoid and non-lymphoid organs, as well as circulating factors interacting with the immune system also contribute to immunosenescence. Overall, immunosenescence is characterized by reduction of immune response, an increase in inflammatory and oxidation background (inflamm-aging), and production of autoantibodies. One of the most prominent age-related changes in the adaptive immune system is the decline in regenerative thymic capacity. Similar aging related defects have also been observed in stroma of the bone marrow. While lymphocytes in infants show a naive phenotype, memory phenotype predominates after midlife. Though immune responses against recall antigens may still be conserved, the ability to mount primary response against novel antigens declines with age. As a result, increased susceptibility to infections, and suboptimal vaccine response is observed in the elderly. Apart from functional alternation in immune cells, there is a low-grade persistent elevation in inflammatory molecules. Inflamm-aging may result from the accumulation of misfold proteins, compromised gut barrier function, chronic infection, obesity, etc. Furthermore, aging is associated with immune dysregulation, with defective resolution of immune response after activation, and impaired clearance of dead cells with sustained inflammation. Excessive inflammation not only impairs antigen specific immunity, but also leads to tissue damage. In fact, this may partly account for the increased mortality of COVID infection in the elderly. Apart from vulnerability to infection and weakened vaccine response, immunosenescence also plays an important role in cancer and autoimmunity in the elderly. Because of increased tissue damage and apoptosis, coupled with inflamm-aging, increased autoantibodies production is observed in the elderly. Nevertheless, there is an age-related increase in peripheral regulatory T cells. While there is an increase in autoimmunity with aging, this does not always translate into an increase in autoimmune disease. On the other hand, the increase in regulatory T cells, along with other immunosuppressive cells and the senescence associated proinflammatory environment, promotes tumor development and progression in the elderly. As immunosenescence has a significant impact on health and disease, better understanding on this process is crucial for research and development in the future geriatric health care.

Enzymatic approaches against SARS-CoV-2 infection with an emphasis on the telomere-associated enzymes.

The pandemic phase of coronavirus disease 2019 (COVID-19) appears to be over in most countries. However, the unexpected behaviour and unstable nature of coronaviruses, including temporary hiatuses, re-emergence, emergence of new variants, and changing outbreak epicentres during the COVID-19 pandemic, have been frequently reported. The mentioned trend shows the fact that in addition to vaccine development, different strategies should be considered to deal effectively with this disease, in long term. In this regard, the role of enzymes in regulating immune responses to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has recently attracted much attention. Moreover, several reports confirm the association of short telomeres with sever COVID-19 symptoms. This review highlights the role of several enzymes involved in telomere length (TL) regulation and explains their relevance to SARS-CoV-2 infection. Apparently, inhibition of telomere shortening (TS) through inhibition and/or activation of these enzymes could be a potential target in the treatment of COVID-19, which may also lead to a reduction in disease severity.

RELATIVE TELOMERE LENGTH IMPACT ON MORTALITY OF COVID-19: SEX DIFFERENCES.

INTRODUCTION: Increasing age is associated with severity and higher mortality of COVID-19. Telomere shortening is associated with higher risk of infections and may be used to identify those patients who are more likely to die. We evaluated the association between relative telomere length (RTL) and COVID-19 mortality. METHODS: RTL was measured in patients hospitalized because of COVID-19. We used Kaplan-Meier method to analyze survival probabilities, and Cox regression to investigate the association between RTL and mortality (30 and 90 days). RESULTS: 608 patients were included in the analysis (mean age =72.5 years, 41.1% women, and 53.8% Caucasic). During the study period, 75 people died from COVID-19 and 533 survived. Lower RTL was associated with a higher risk of death in women either at 30 (adjusted HR (aHR)=3.33; 95%CI=1.05-10.00; p=0.040) and at 90 days (aHR=3.57; 95%CI=1.23-11.11; p=0.019). CONCLUSION: Lower RTL was associated with a higher risk of dying of COVID-19 in women. This finding suggests that RTL has an essential role in the prognosis of this subset of the population. This article is protected by copyright. All rights reserved.

Causal association of epigenetic aging and COVID-19 severity and susceptibility: A bidirectional Mendelian randomization study.

Observational data from China, the United States, France, and Italy suggest that chronological age is an adverse COVID-19 outcome risk factor, with older patients having a higher severity and mortality rate than younger patients. Most studies have gotten the same view. However, the role of aging in COVID-19 adverse effects is unclear. To more accurately assess the effect of aging on adverse COVID-19, we conducted this bidirectional Mendelian randomization (MR) study. Epigenetic clocks and telomere length were used as biological indicators of aging. Data on epigenetic age (PhenoAge, GrimAge, Intrinsic HorvathAge, and HannumAge) were derived from an analysis of biological aging based on genome-wide association studies (GWAS) data. The telomere length data are derived from GWAS and the susceptibility and severity data are derived from the COVID-19 Host Genetics Initiative (HGI). Firstly, epigenetic age and telomere length were used as exposures, and following a screen for appropriate instrumental variables, we used random-effects inverse variance weighting (IVW) for the main analysis, and combined it with other analysis methods (e.g., MR Egger, Weighted median, simple mode, Weighted mode) and multiple sensitivity analysis (heterogeneity analysis, horizontal multiplicity analysis, "leave-one-out" analysis). For reducing false-positive rates, Bonferroni corrected significance thresholds were used. A reverse Mendelian randomization analysis was subsequently performed with COVID-19 susceptibility and severity as the exposure. The results of the MR analysis showed no significant differences in susceptibility to aging and COVID-19. It might suggest that aging is not a risk factor for COVID-19 infection (P-values are in the range of 0.05-0.94). According to the results of our analysis, we found that aging was not a risk factor for the increased severity of COVID-19 (P > 0.05). However, severe COVID-19 can cause telomere lengths to become shorter (beta = -0.01; se = 0.01; P = 0.02779). In addition to this, severe COVID-19 infection can slow the acceleration of the epigenetic clock "GrimAge" (beta = -0.24, se = 0.07, P = 0.00122), which may be related to the closely correlation of rs35081325 and COVID-19 severity. Our study provides partial evidence for the causal effects of aging on the susceptibility and severity of COVID-19.

Shorter telomere length is associated with COVID-19 hospitalization and with persistence of radiographic lung abnormalities.

BACKGROUND: Age and comorbidity are the main determinants of COVID-19 outcome. Shorter leukocyte telomere length (TL), a hallmark of biological aging, has been associated with worse COVID-19 outcomes. We sought to determine TL in patients with severe COVID-19 requiring hospitalization to analyze whether clinical outcomes and post-COVID-19 manifestations are associated with shorter TL. RESULTS: We analyzed 251 patients with PCR-confirmed COVID-19, hospitalized in the first months of the pandemics. We determined TL in PBL at admission by quantitative-PCR (qPCR) analysis in patients. A healthy cohort from the same area with a similar age range (n = 169) was used to calculate TL Z-scores. After hospital discharge, 144 COVID-19 survivors were followed-up for persistent COVID-19 manifestations. A second TL determination was performed in a smaller group of 63 patients 1 year later and compared with baseline TL. Hospitalized COVID-19 patients had a decreased baseline age-adjusted TL Z-score compared to the reference group. No differences in Z-scores were observed in patients with different COVID-19 outcomes, classified as WHO ordinal scores. In 144 patients, followed for a median of 8 months, post-COVID manifestations were not associated to differences in TL. Persistence of lung radiographic abnormalities was associated with shorter baseline TL. In patients with a second TL determination, further telomere shortening (TS) was observed in 35% and telomere lengthening in 49%. Patients with further TS had suffered a more severe disease. CONCLUSION: Shorter TL is associated with COVID-19 hospitalization but not with hospital clinical outcomes nor with persistent post-COVID-19 manifestations. Delayed resolution of radiographic lung abnormalities was also associated with shorter TL.

Telomere Length and COVID-19 Outcomes: A Two-Sample Bidirectional Mendelian Randomization Study.

Observational studies have found a relationship between directly measured short leukocyte telomere length (LTL) and severe coronavirus disease 19 (COVID-19). We investigated the causal association between genetically predicted LTL and COVID-19 susceptibility or severity. A previous genome-wide association study (GWAS) of 78,592 European-ancestry participants identified single nucleotidepolymorphisms (SNPs) that can be utilized to genetically predict LTL. Summary-level data for COVID-19 outcomes were analyzed from the COVID-19 Host Genetics Initiative. A two-sample bidirectional Mendelian randomization (MR) study was designed to evaluate these causal relationships. Using an inverse-weighted MR analysis and population-based controls, genetically predicted LTL did not reveal any significant association with COVID-19 susceptibility (odds ratio (OR): 0.94; 95% CI: 0.85-1.04; p = 0.202) or severity (OR: 0.85; 95% CI: 0.70-1.03; p = 0.099). Similar results were found for five other definitions of cases/controls and/or COVID-19 outcomes. Six additional MR methods and sensitivity analyses were conducted after removing variants with potential horizontal pleiotropy and including variants at a liberal significance level, which produced similar results. Using SNPs identified for the prediction of LTL from another GWAS study, we found a non-significant association for COVID-19 susceptibility or severity with narrower CIs toward the null hypothesis. No proof of genetically predicted COVID-19 phenotypes remained causally associated with genetically predicted LTL, and the null association was consistent with a lack of significant genetic correlation. Genetic evidence does not support shorter LTL as a causal risk factor for COVID-19 susceptibility or severity.

A cautionary note on altered pace of aging in the COVID-19 era.

Coronavirus disease 2019 (COVID-19) is highly age-dependent due to hi-jacking the molecular control of the immune cells by the severe acute respiratory syndrome-corona virus 2 (SARS-CoV-2) leading to aberrant DNA methylation (DNAm) pattern of blood in comparison to normal individuals. These epigenetic modifications have been linked to perturbations to the epigenetic clock, development of long COVID-19 syndrome, and all-cause mortality risk. I reviewed the effects of COVID-19 on different molecular age markers such as the DNAm, telomere length (TL), and signal joint T-cell receptor excision circle (sjTREC). Integrating the accumulated clinical research data, COVID-19 and novel medical management may alter the pace of aging in adult individuals (<60 years). As such, COVID-19 might be a confounder in epigenetic age estimation similar to life style diversities, pathogens and pathologies which may influence the interpretation of DNAm data. Similarly, the SARS-CoV-2 affects T-lymphocyte function with possible influence on sjTREC levels. In contrast, TL measurements performed years before the SARS-CoV-2 pandemic proved that short TL predisposes to severe COVID- 19 independently from chronological age. However, the persistence of COVID-19 epigenetic scars and the durability of the immune response after vaccination and their effect on the ongoing pace of aging are still unknown. In the light of these data, the heterogeneous nature of the samples in these studies mandates a systematic evaluation of the currrent methods. SARS-CoV-2 may modify the reliability of the age estimation models in real casework because blood is the most common biological sample encountered in forensic contexts.