Human Herpesvirus 8 infection may contribute to oxidative stress in diabetes type 2 patients

Seasonal patterns of oxidative stress markers in captive Asian elephants in Thailand and relationships to elephant endotheliotropic herpesvirus shedding

Introduction

Oxidative stress refers to an imbalance between oxidant and antioxidant activity and accumulation of reactive oxygen species, which can have detrimental effects on animal health. Annual fluctuations in oxidative stress status can occur, increasing disease susceptibility during certain time periods. However, a full understanding of factors related to oxidative stress in Asian elephants and how to mitigate the negative consequences is lacking.

Methods

This study measured six serum oxidative stress markers [reactive oxygen species (ROS), malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), albumin, glutathione peroxidase (GPx), and catalase] and two stress markers [serum cortisol and fecal glucocorticoid metabolites (fGCM)] in 23 captive Asian elephants in Thailand over a 12 months period to examine relationships with age and season.

Results

Seasonal variations were observed, with several markers exhibiting significantly higher concentrations in the summer (ROS, MDA, 8-OHdG, albumin) and lower values during the rainy/winter seasons (MDA, 8-OHdG, albumin, catalase). By contrast, GPx was the only marker to be highest during the rainy season. For the stress markers, higher fGCM concentrations were noted during the rainy season, which contrasts with earlier studies showing more activity in the winter (tourist season). Positive correlations were found between the temperature-humidity index and ROS, GPx, and fGCM, while a negative correlation was observed with serum albumin. Elephant endotheliotropic herpesvirus (EEHV) shedding events were associated with higher concentrations of ROS and MDA. A moderate negative correlation was observed between 8-OHdG and the PCR threshold cycle of EEHV shedding (Ct), indicating DNA damage may be involved in EEHV shedding in elephants.

Discussion

Results revealed significant age and seasonal effects on several oxidative stress markers, indicating those factors should be considered in study design and data interpretation. There also may be physiological adaptations in oxidative stress conditions in relation to environmental changes that could impact health outcomes.

Cholesterol-autoxidation metabolites in host defense against infectious diseases

Cholesterol plays essential roles in biological processes, including cell membrane stability and myelin formation. Cholesterol can be metabolized to oxysterols by enzymatic or nonenzymatic ways. Nonenzymatic cholesterol metabolites, also called cholesterol-autoxidation metabolites, are formed dependent on the oxidation of reactive oxygen species (ROS) such as OH• or reactive nitrogen species, such as ONOO- . Cholesterol-autoxidation metabolites are abundantly produced in diseases such as inflammatory bowel disease and atherosclerosis, which are associated with oxidative stress. Recent studies have shown that cholesterol-autoxidation metabolites can further regulate the immune system. Here, we review the literature and summarize how cholesterol-autoxidation metabolites, such as 25-hydroxycholesterol (25-OHC), 7α/β-OHC, and 7-ketocholesterol, deal with the occurrence and development of infectious diseases through pattern recognition receptors, inflammasomes, ROS production, nuclear receptors, G-protein-coupled receptor 183, and lipid availability. In addition, we include the research regarding the roles of these metabolites in COVID-19 infection and discuss our viewpoints on the future research directions.

Contribution of carbohydrate-related metabolism in Herpesvirus infections

Human herpesviruses are enveloped viruses with double-stranded linear DNA genomes highly prevalent in the human population. These viruses are subdivided into three subfamilies, namely alphaherpesvirinae (herpes simplex virus type 1, HSV-1; herpes simplex virus type 2, HSV-2; and varicella-zoster virus, VZV), betaherpesvirinae (human cytomegalovirus, HCMV; human herpesvirus 6, HHV-6; and human herpesvirus 7, HHV-7) and gammaherpesvirinae (Epstein-Barr virus, EBV; and Kaposi's sarcoma-associated herpesvirus, KSHV). Besides encoding numerous molecular determinants to evade the host antiviral responses, these viruses also modulate cellular metabolic processes to promote their replication. Here, we review and discuss existing studies describing an interplay between carbohydrate metabolism and the replication cycle of herpesviruses, altogether highlighting potentially new molecular targets based on these interactions that could be used to block herpesvirus infections.

Measures of Oxidative Status Markers in Relation to Age, Sex, and Season in Sick and Healthy Captive Asian Elephants in Thailand

Oxidative stress is a pathological condition that can have adverse effects on animal health, although little research has been conducted on wildlife species. In this study, blood was collected from captive Asian elephants for the assessment of five serum oxidative status markers (reactive oxygen species (ROS) concentrations; malondialdehyde, MDA; albumin; glutathione peroxidase, GPx; and catalase) in healthy (n = 137) and sick (n = 20) animals. Health problems consisted of weakness, puncture wounds, gastrointestinal distress, eye and musculoskeletal problems, and elephant endotheliotropic herpesvirus hemorrhagic disease (EEHV-HD). Fecal samples were also collected to assess glucocorticoid metabolites (fGCMs) as a measure of stress. All data were analyzed in relation to age, sex, sampling season, and their interactions using generalized linear models, and a correlation matrix was constructed. ROS and serum albumin concentrations exhibited the highest concentrations in aged elephants (>45 years). No sex differences were found for any biomarker. Interactions were observed for age groups and seasons for ROS and catalase, while GPx displayed a significant interaction between sex and season. In pairwise comparisons, significant increases in ROS and catalase were observed in summer, with higher ROS concentrations observed only in the adult female group. Lower catalase activity was exhibited in juvenile males, subadult males, adult females, and aged females compared to subadult and adult elephants (males and females) in winter and the rainy season. There was a positive association between catalase activity and fGCMs (r = 0.23, p < 0.05), and a number of red blood cell parameters were positively associated with several of these biomarkers, suggesting high oxidative and antioxidative activity covary in red cells (p < 0.05). According to health status, elephants with EEHV-HD showed the most significant changes in oxidative stress markers, with MDA, GPx, and catalase being higher and albumin being lower than in healthy elephants. This study provides an analysis of understudied health biomarkers in Asian elephants, which can be used as additional tools for assessing the health condition of this species and suggests age and season may be important factors in data interpretation.

Oxysterols in the Immune Response to Bacterial and Viral Infections

Oxidized cholesterols, the so-called oxysterols, are widely known to regulate cholesterol homeostasis. However, more recently oxysterols have emerged as important lipid mediators in the response to both bacterial and viral infections. This review summarizes our current knowledge of selected oxysterols and their receptors in the control of intracellular bacterial growth as well as viral entry into the host cell and viral replication. Lastly, we briefly discuss the potential of oxysterols and their receptors as drug targets for infectious and inflammatory diseases.

Potential Role for Herpesviruses in Alzheimer's Disease

Across the fields of virology and neuroscience, the role of neurotropic viruses in Alzheimer's disease (AD) has received renewed enthusiasm, with a particular focus on human herpesviruses (HHVs). Recent genomic analyses of brain tissue collections and investigations of the antimicrobial responses of amyloid-β do not exclude a role of HHVs in contributing to or accelerating AD pathogenesis. Due to continued expansion in our aging cohort and the lack of effective treatments for AD, this composition examines a potential neuroviral theory of AD in light of these recent data. Consideration reveals a possible viral "Hit-and-Run" scenario of AD, as well as neurobiological mechanisms (i.e., neuroinflammation, protein quality control, oxidative stress) that may increase risk for AD following neurotropic infection. Although limitations exist, this theoretical framework reveals several novel therapeutic targets that may prove efficacious in AD.

7-Ketocholesterol: Effects on viral infections and hypothetical contribution in COVID-19

7-Ketocholesterol, which is one of the earliest cholesterol oxidization products identified, is essentially formed by the auto-oxidation of cholesterol. In the body, 7-ketocholesterol is both provided by food and produced endogenously. This pro-oxidant and pro-inflammatory molecule, which can activate apoptosis and autophagy at high concentrations, is an abundant component of oxidized Low Density Lipoproteins. 7-Ketocholesterol appears to significantly contribute to the development of age-related diseases (cardiovascular diseases, age-related macular degeneration, and Alzheimer's disease), chronic inflammatory bowel diseases and to certain cancers. Recent studies have also shown that 7-ketocholesterol has anti-viral activities, including on SARS-CoV-2, which are, however, lower than those of oxysterols resulting from the oxidation of cholesterol on the side chain. Furthermore, 7-ketocholesterol is increased in the serum of moderately and severely affected COVID-19 patients. In the case of COVID-19, it can be assumed that the antiviral activity of 7-ketocholesterol could be counterbalanced by its toxic effects, including pro-oxidant, pro-inflammatory and pro-coagulant activities that might promote the induction of cell death in alveolar cells. It is therefore suggested that this oxysterol might be involved in the pathophysiology of COVID-19 by contributing to the acute respiratory distress syndrome and promoting a deleterious, even fatal outcome. Thus, 7-ketocholesterol could possibly constitute a lipid biomarker of COVID-19 outcome and counteracting its toxic effects with adjuvant therapies might have beneficial effects in COVID-19 patients.

Non-autoimmune diabetes mellitus and the risk of virus infections: a systematic review and meta-analysis of case-control and cohort studies

A significant number of studies invoked diabetes as a risk factor for virus infections, but the issue remains controversial. We aimed to examine whether non-autoimmune diabetes mellitus enhances the risk of virus infections compared with the risk in healthy individuals without non-autoimmune diabetes mellitus. In this systematic review and meta-analysis, we assessed case-control and cohort studies on the association between non-autoimmune diabetes and viruses. We searched PubMed, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and Web of Science with no language restriction, to identify articles published until February 15, 2021. The main outcome assessment was the risk of virus infection in individuals with non-autoimmune diabetes. We used a random-effects model to pool individual studies and assessed heterogeneity (I²) using the χ2 test on Cochrane's Q statistic. This study is registered with PROSPERO, number CRD42019134142. Out of 3136 articles identified, we included 68 articles (90 studies, as the number of virus and or diabetes phenotype varied between included articles). The summary OR between non-autoimmune diabetes and virus infections risk were, 10.8(95% CI: 10.3-11.4; 1-study) for SARS-CoV-2; 3.6(95%CI: 2.7-4.9, I² = 91.7%; 43-studies) for HCV; 2.7(95% CI: 1.3-5.4, I² = 89.9%, 8-studies;) for HHV8; 2.1(95% CI: 1.7-2.5; 1-study) for H1N1 virus; 1.6(95% CI: 1.2-2.13, I² = 98.3%, 27-studies) for HBV; 1.5(95% CI: 1.1-2.0; 1-study) for HSV1; 3.5(95% CI: 0.6-18.3 , I² = 83.9%, 5-studies) for CMV; 2.9(95% CI: 1-8.7, 1-study) for TTV; 2.6(95% CI: 0.7-9.1, 1-study) for Parvovirus B19; 0.7(95% CI: 0.3-1.5 , 1-study) for coxsackie B virus; and 0.2(95% CI: 0-6.2; 1-study) for HGV. Our findings suggest that, non-autoimmune diabetes is associated with increased susceptibility to viruses especially SARS-CoV-2, HCV, HHV8, H1N1 virus, HBV and HSV1. Thus, these viruses deserve more attention from diabetes health-care providers, researchers, policy makers, and stakeholders for improved detection, overall proper management, and efficient control of viruses in people with non-autoimmune diabetes.

Update on Kaposi sarcoma-associated herpesvirus (KSHV or HHV8) - review

Human herpesvirus 8 (HHV8), also known as Kaposi sarcoma-associated herpesvirus (KSHV), is one of the few pathogens recognized as direct carcinogen, being involved in the pathogenesis of Kaposi sarcoma, primary effusion lymphoma and multicentric Castleman disease. KSHV is a relatively recently discovered virus, with still limited possibilities for diagnosis and treatment. Therefore, ongoing studies are trying to answer the main issues related to the management of KSHV infection and its associated diseases. This review updates the current knowledge of the KSHV infection, discussing aspects related to epidemiology, virological features, clinical manifestations, diagnosis and treatment.

Human Herpesvirus 8 and Host-Cell Interaction: Long-Lasting Physiological Modifications, Inflammation and Related Chronic Diseases

Oncogenic and latent-persistent viruses belonging to both DNA and RNA groups are known to cause serious metabolism alterations. Among these, the Human Herpesvirus 8 (HHV8) infection induces stable modifications in biochemistry and cellular metabolism, which in turn affect its own pathological properties. HHV8 enhances the expression of insulin receptors, supports the accumulation of neutral lipids in cytoplasmic lipid droplets and induces alterations in both triglycerides and cholesterol metabolism in endothelial cells. In addition, HHV8 is also known to modify immune response and cytokine production with implications for cell oxidative status (i.e., reactive oxygen species activation). This review underlines the recent findings regarding the role of latent and persistent HHV8 viral infection in host physiology and pathogenesis.