Adipogenic human adenovirus Ad-36 induces commitment, differentiation, and lipid accumulation in human adipose-derived stem cells

Modulation of the Inflammatory Response by Adenovirus 36 in Patients with Obesity and Type 2 Diabetes: A Nested Case-Control Study Within a Cohort

Human adenovirus 36 (HAdV-36) is associated with obesity, potentially by promoting adipocyte proliferation and differentiation. Although linked to increased fat storage, HAdV-36 is also correlated with improved insulin sensitivity. Given its potential role in modulating adipose tissue and promoting a less inflammatory metabolic profile, its impacts on pro- and anti-inflammatory cytokine secretion remain unclear.

METHODS

This nested case-control study compared cytokine levels (IL-10, IL-2, IL-6, IL-8, and TNF-α) between patients with and without HAdV-36 infection. A total of 76 participants were included, with 37 in the control group (HAdV-36 negative) and 39 classified as cases (HAdV-36 positive).

RESULTS

HAdV-36 seropositive individuals exhibited significantly lower IL-6 levels and higher IL-8 levels than seronegative participants. Additionally, they had lower glucose levels, suggesting a potential link between HAdV-36 and metabolic regulation.

CONCLUSIONS

These findings support the hypothesis that HAdV-36 may influence inflammatory and metabolic responses by modulating cytokine expression and glucose levels. Further research is needed to clarify the underlying mechanisms and their implications for metabolic health.

Characterization of the differences in lipid profiles and volatile compounds of adipose stem cells adipogenic differentiation and adipocytic transdifferentiation of muscle stem cells from large yellow croakers based on UPLC-MS/MS and GC-IMS

Lipids contribute significantly to the flavor of cell-cultured fish meat as precursor components of flavor compounds. Here, we initially reported the differences in lipid metabolite profiles and volatile compounds between adipogenic differentiation of adipose stem cells (ASCs) and adipocytic transdifferentiation of muscle stem cells (MSCs) from large yellow croakers. A total of 2106 lipid metabolites were identified by UPLC-MS/MS. Compared with the MSCs group, 1263 differentially expressed lipid metabolites were found in the ASCs group, with 1026 up-regulated lipid metabolites and 237 down-regulated ones. The main lipid differences were fatty acyls (FAs) and glycerolipids (GL). GC-IMS identified a total of 47 volatile compounds. Volatile compounds such as ethyl laurate, nonanal, and 2,3-pentanedione were significantly higher in the ASCs group than in the MSCs group. GC-IMS results indicated that the ASCs group was more flavorful. This study provides a theoretical basis for developing cell-cultured fish meat with a familiar flavor.

Dogs are a susceptible species to human adenovirus 36 infection: New insights into the host range of the virus causing infectious obesity

The prevalence of obesity within the human population is escalating globally yearly. Obesity constitutes a complex ailment with diverse etiological factors. Recently, the infectious side of obesity aetiology, implicating pathogens such as human adenovirus 36 (HAdV-D36), has gained attention. Research indicates that HAdV-D36 can infect humans and various animal species, including mice, monkeys, and chickens, inducing obesity in the animals. The present study aimed to confirm whether companion animals, like dogs, can also host HAdV-D36 and which biochemical markers can be helpful to indicate its presence. The blood of 118 canine subjects was analysed using serological techniques for determining the presence of antibodies and screened for biochemical parameters like leptin, cholesterol, and triglycerides. The presence of anti-HAdV-D36 antibodies was confirmed in 80 of the 118 tested individuals. The investigation of the relationship between antibody levels and the concentrations of cholesterol, triglycerides, and leptin in blood serum revealed a positive correlation between antibody titers and triglyceride levels in the tested samples. Furthermore, utilizing cell cultures facilitated successful isolation of HAdV-D36 from the adipose tissue of 14 dogs under investigation. Our study adds to general knowledge of the range of hosts susceptible to the pathogen in question and highlights the discrepancies in the virus mechanisms found in the existing literature. Given the diverse host range of the virus, which extends to companion animals, a zoonotic potential cannot be ruled out, which, however, requires further extensive research.

Extended receptor repertoire of an adenovirus associated with human obesity

Human adenovirus type 36 (HAdV-D36) has been putatively linked to obesity in animals and has been associated with obesity in humans in some but not all studies. Despite extensive epidemiological research there is limited information about its receptor profile. We investigated the receptor portfolio of HAdV-D36 using a combined structural biology and virology approach. The HAdV-D36 fiber knob domain (FK), which mediates the primary attachment of many HAdVs to host cells, has a significantly elongated DG loop that alters known binding interfaces for established adenovirus receptors such as the coxsackie- and adenovirus receptor (CAR) and CD46. Our data suggest that HAdV-D36 attaches to host cells using a versatile receptor pool comprising sialic acid-containing glycans and CAR. Sialic acids are recognized at the same binding site used by other HAdVs of species D such as HAdV-D37. Using glycan microarrays, we demonstrate that HAdV-D36 displays a binding preference for glycans containing a rare sialic acid variant, 4-O,5-N-diacetylneuraminic acid, over the more common 5-N-acetylneuraminic acid. To date, this sialic acid variant has not been detected in humans, although it can be synthesized by various animal species, including a range of domestic and livestock animals. Taken together, our results indicate that HAdV-D36 has evolved to recognize a specialized set of primary attachment receptors that are different from known HAdV types and coincides with a unique host range and pathogenicity profile.

E4orf1: The triple agent of adenovirus - Unraveling its roles in oncogenesis, infectious obesity and immune responses in virus replication and vector therapy

Human Adenoviruses (HAdV) are nearly ubiquitous pathogens comprising numerous sub-types that infect various tissues and organs. Among many encoded proteins that facilitate viral replication and subversion of host cellular processes, the viral E4orf1 protein has emerged as an intriguing yet under-investigated player in the complex interplay between the virus and its host. E4orf1 has gained attention as a metabolism activator and oncogenic agent, while recent research is showing that E4orf1 may play a more important role in modulating cellular pathways such as PI3K-Akt-mTOR, Ras, the immune response and further HAdV replication stages than previously anticipated. In this review, we aim to explore the structure, molecular mechanisms, and biological functions of E4orf1, shedding light on its potentially multifaceted roles during HAdV infection, including metabolic diseases and oncogenesis. Furthermore, we discuss the role of functional E4orf1 in biotechnological applications such as Adenovirus (AdV) vaccine vectors and oncolytic AdV. By dissecting the intricate relationships between HAdV types and E4orf1 proteins, this review provides valuable insights into viral pathogenesis and points to promising areas of future research.

The human adenovirus PI3K-Akt activator E4orf1 is targeted by the tumor suppressor p53

Human adenoviruses (HAdV) are classified as DNA tumor viruses due to their potential to mediate oncogenic transformation in non-permissive mammalian cells and certain human stem cells. To achieve transformation, the viral early proteins of the E1 and E4 regions must block apoptosis and activate proliferation: the former predominantly through modulating the cellular tumor suppressor p53 and the latter by activating cellular pro-survival and pro-metabolism protein cascades, such as the phosphoinositide 3-kinase (PI3K-Akt) pathway, which is activated by HAdV E4orf1. Focusing on HAdV-C5, we show that E4orf1 is necessary and sufficient to stimulate Akt activation through phosphorylation in H1299 cells, which is not only hindered but repressed during HAdV-C5 infection with a loss of E4orf1 function in p53-positive A549 cells. Contrary to other research, E4orf1 localized not only in the common, cytoplasmic PI3K-Akt-containing compartment, but also in distinct nuclear aggregates. We identified a novel inhibitory mechanism, where p53 selectively targeted E4orf1 to destabilize it, also stalling E4orf1-dependent Akt phosphorylation. Co-IP and immunofluorescence studies showed that p53 and E4orf1 interact, and since p53 is bound by the HAdV-C5 E3 ubiquitin ligase complex, we also identified E4orf1 as a novel factor interacting with E1B-55K and E4orf6 during infection; overexpression of E4orf1 led to less-efficient E3 ubiquitin ligase-mediated proteasomal degradation of p53. We hypothesize that p53 specifically subverts the pro-survival function of E4orf1-mediated PI3K-Akt activation to protect the cell from metabolic hyper-activation or even transformation.IMPORTANCEHuman adenoviruses (HAdV) are nearly ubiquitous pathogens comprising numerous subtypes that infect various tissues and organs. Among many encoded proteins that facilitate viral replication and subversion of host cellular processes, the viral E4orf1 protein has emerged as an intriguing yet under-investigated player in the complex interplay between the virus and its host. Nonetheless, E4orf1 has gained attention as a metabolism activator and oncogenic agent, while recent research is showing that E4orf1 may play a more important role in modulating the cellular pathways such as phosphoinositide 3-kinase-Akt-mTOR. Our study reveals a novel and general impact of E4orf1 on host mechanisms, providing a novel basis for innovative antiviral strategies in future therapeutic settings. Ongoing investigations of the cellular pathways modulated by HAdV are of great interest, particularly since adenovirus-based vectors actually serve as vaccine or gene vectors. HAdV constitute an ideal model system to analyze the underlying molecular principles of virus-induced tumorigenesis.

Immunogenetic Aspects of Sarcopenic Obesity

Sarcopenic obesity (SO) is a combination of obesity and sarcopenia, with diagnostic criteria defined as impaired skeletal muscle function and altered body composition (e.g., increased fat mass and reduced muscle mass). The mechanism of SO is not yet perfectly understood; however, the pathogenesis includes aging and its complications, chronic inflammation, insulin resistance (IR), and hormonal changes. Genetic background is apparent in the pathogenesis of isolated obesity, which is most often polygenic and is characterized by the additive effect of various genetic factors. The genetic etiology has not been strictly established in SO. Still, many data confirm the existence of pathogenic gene variants, e.g., Fat Mass and Obesity Associated Gene (FTO), beta-2-adrenergic receptor (ADRB2) gene, melanocortin-4 receptor (MC4R) and others with obesity. The literature on the role of these genes is scarce, and their role has not yet been thoroughly established. On the other hand, the involvement of systemic inflammation due to increased adipose tissue in SO plays a significant role in its pathophysiology through the synthesis of various cytokines such as monocyte chemoattractant protein-1 (MCP-1), IL-1Ra, IL-15, adiponectin or CRP. The lack of anti-inflammatory cytokine (e.g., IL-15) can increase SO risk, but further studies are needed to evaluate the exact mechanisms of implications of various cytokines in SO individuals. This manuscript analyses various immunogenetic and non-genetic factors and summarizes the recent findings on immunogenetics potentially impacting SO development.

Pharmacomicrobiomics and Drug-Infection Interactions: The Impact of Commensal, Symbiotic and Pathogenic Microorganisms on a Host Response to Drug Therapy

Microorganisms have a close relationship with humans, whether it is commensal, symbiotic, or pathogenic. Recently, it has been documented that microorganisms may influence the response to drug therapy. Pharmacomicrobiomics is an emerging field that focuses on the study of how variations in the microbiome affect the disposition, action, and toxicity of drugs. Two additional sciences have been added to complement pharmacomicrobiomics, namely toxicomicrobiomics, which explores how the microbiome influences drug metabolism and toxicity, and pharmacoecology, which refers to modifications in the microbiome as a result of drug administration. In this context, we introduce the concept of "drug-infection interaction" to describe the influence of pathogenic microorganisms on drug response. This review analyzes the current state of knowledge regarding the relevance of microorganisms in the host's response to drugs. It also highlights promising areas for future research and proposes the term "drug-infection interaction" as an extension of pharmacomicrobiomics.

Effect of Human Adenovirus 36 on Response to Metformin Monotherapy in Obese Mexican Patients with Type 2 Diabetes: A Prospective Cohort Study

Human adenovirus 36 (HAdV-36) has been associated with obesity and changes in glucose and lipid metabolism. The virus has been reported to increase insulin sensitivity and paradoxically promote weight gain. Because of its effects on metabolism, infection with the virus could alter the response to several drugs used to treat type 2 diabetes (DM2), such as metformin. The aim of this study was to test whether HAdV-36 affects the response to metformin in a group of obese patients with DM2.

METHODS

In a prospective cohort study, 103 obese patients with newly diagnosed DM2 were divided into two groups based on their HAdV-36 seropositivity (+HAdV-36 and -HAdV-36). Weight, glucose, cholesterol, triglycerides, body mass index, body fat percentage, and waist and hip circumference were measured and compared in both groups at baseline and after 45 days of metformin treatment.

RESULTS

Only glucose was significantly lower in the +HAdV-36 group at baseline, while all other variables were similar between the two study groups. After 45 days of follow-up, it was observed that the effect of metformin did not differ between the groups, but the variables improved significantly after treatment.

CONCLUSIONS

In this study, we did not find that HAdV-36 had an effect on the response to metformin in obese patients with DM2.

Inflammatory cytokines and chemokines in obese adolescents with antibody against to adenovirus 36

Obesity in adolescents has reached epidemic proportions and is associated with the inflammatory response and viral infections. The aim of this study was to understand the profile of inflammatory cytokines and chemokines associated with the inflammatory response and metabolic syndrome (MetS) in obese adolescents with positive serology for adenovirus 36 (ADV36). Thirty-six overweight, 36 obese, and 25 severe obesity adolescents aged 10 to 16 years were included in the study. The following variables were analyzed: sex, age, body mass index (BMI), blood pressure, total cholesterol and fractions, triglycerides, glucose, serum cytokine concentrations, and ADV36 antibodies. Cytokines and chemokines were quantified by cytometry and ADV36 serology was determined by enzyme-linked immunosorbent assay (ELISA). The results showed higher levels of the cytokines interleukin-1beta (IL-1β), IL-6, IL-10 and of the chemokine interferon-gamma-inducible protein 10 (IP-10) in severe obesity adolescents compared to the obese and overweight groups, as well as in the group with MetS compared to the group without this syndrome. The frequency of ADV36-positive individuals did not differ between groups. The findings revealed differences in BMI between the obese and severe obesity groups versus the overweight group in the presence of positivity for ADV36, suggesting an association with weight gain and possibly MetS installation.

Adipocyte commitment of 3T3-L1 cells is required to support human adenovirus 36 productive replication concurrent with altered lipid and glucose metabolism

Human adenovirus 36 (HAdV-D36) can cause obesity in animal models, induces an adipogenic effect and increased adipocyte differentiation in cell culture. HAdV-D36 infection alters gene expression and the metabolism of the infected cells resulting in increased glucose internalization and triglyceride accumulation. Although HAdV-D36 prevalence correlates with obesity in humans, whether human preadipocytes may be targeted in vivo has not been determined and metabolic reprogramming of preadipocytes has not been explored in the context of the viral replication cycle. HAdV-D36 infection of the mouse fibroblasts, 3T3-L1 cells, which can differentiate into adipocytes, promotes proliferation and differentiation, but replication of the virus in these cells is abortive as indicated by short-lived transient expression of viral mRNA and a progressive loss of viral DNA. Therefore, we have evaluated whether a productive viral replication cycle can be established in the 3T3-L1 preadipocyte model under conditions that drive the cell differentiation process. For this purpose, viral mRNA levels and viral DNA replication were measured by RT-qPCR and qPCR, respectively, and viral progeny production was determined by plaque assay. The lipogenic effect of infection was evaluated with Oil Red O (ORO) staining, and expression of genes that control lipid and glucose metabolism was measured by RT-qPCR. In the context of a viral productive cycle, HAdV-D36 modulated the expression of the adipogenic genes, C/EBPα, C/EBPβ and PPARγ, as well as intracellular lipid accumulation, and the infection was accompanied by altered expression of glucolytic genes. The results show that only adipocyte-committed 3T3-L1 cells are permissive for the expression of early and late viral mRNAs, as well as viral DNA replication and progeny production, supporting productive HAdV-D36 viral replication, indicating that a greater effect on adipogenesis occurs in adipocytes that support productive viral replication.

Adenovirus 36 infection and obesity risk: current understanding and future therapeutic strategies

INTRODUCTION

Obesity, a multifactorial disease caused by the interaction between genetic characteristics, metabolism, lifestyle, and environmental factors, is a major global health problem and is currently defined as a pandemic phenomenon. This disease is determined by an interaction of several factors, but the imbalance between energy consumption and expenditure seems to be the crucial point. In some cases, there is no linearity between exposure to those factors that cause the onset of obesity. A striking example of the occurrence of obesity despite no obvious risk factors is that of obesity induced by viral infections. The most important of such viruses appears to be human adenovirus 36 (Adv36).

AREAS COVERED

This review covers the relation between obesity and infection by Adv36 in humans. Also, discussed are the opportunities of prevention or treatment for the effects of Adv36 in human body.

EXPERT OPINION

The role of Ad36 in the development of obesity has already been established. Future research should focus on the development of vaccines against this agent, drug discovery for infected individuals, and effective therapeutic uses of E4orf1 gene protein for diabetes and other diseases in clinical practice.

Association of adenovirus 36 infection and obesity; An updated meta-analysis of community-based studies

As a health problem, obesity has several risk factors; it has been suggested that human adenovirus type 36 (HAdV-36) infections may possibly be associated with obesity. This updated meta-analysis was designed and conducted with an emphasis on articles published from 2015 to 2020. The PubMed, Web of Science, and Scopus databases were searched up to 1 December 2020. Overall, pooled prevalence and odds ratio of antibodies against HAdV-36 in people with obesity and controls was assessed among different ages. Case-control and cohort studies were included in the analysis. The overall prevalence of HAdV-36 infection in obese population was 31% (CI: 0.24%-0.38%) which was 32% in cases and 27% in controls, respectively; a significant association was found between the cases and the controls (OR, 1.84; 95% CI, 1.39-2.43), especially in children younger than 18 years of age (OR, 2.44; 95% CI, 1.85-3.22). A significant association between adenovirus infection and obesity was found, especially in adolescents.

Adenovirus 36 prevalence and association with human obesity: a systematic review

INTRODUCTION

Obesity has numerous etiologies and includes biological factors. Studies have demonstrated that the human adenovirus subtype 36 (Adv36) is an adipogenic agent and causes metabolic alterations. Study results on the prevalence of Adv36 and clinical effects in humans vary substantially. This was a systematic review to summarize the studies on the prevalence of Adv36 infection and its association with human obesity.

METHODS

A systematic literature review was conducted using the preferred reporting items for systematic reviews and meta-analysis (PRISMA). Observational or experimental studies found in the Medline, Embase, LILACS, Science Direct and SciELO databases that presented results on the prevalence of Adv36 in humans were included.

RESULTS

Thirty-seven studies were screened. A total of 10,300 adults aged 18-70 years and 4585 children and adolescents aged 3-18 years were assessed. The average prevalence of Adv36 among adults was 22.9%, ranging from 5.5% to 49.8%. Among children and adolescents, the average prevalence of Adv36 was 28.9%, ranging from 7.5% to 73.9%. There was a positive statistical relationship between Adv36 and weight gain, obesity, or metabolic changes in 31 studies. However, in four studies there was no association with obesity, and in one, no association was described. One of the studies showed an inverse correlation, i.e., Adv36 was a protective factor against obesity.

CONCLUSION

Strong evidence suggested a positive association between viral infection and obesity. However, due to the multi-causality of obesity and heterogeneity of studies, diagnostic tests should be standardized and easily accessible by the population to estimate the overall prevalence of Adv36 infection and its association with obesity.

Mechanisms of repigmentation induced by photobiomodulation therapy in vitiligo

Photobiomodulation (PBM) therapy is based on the exposure of biological tissues to low-level laser light (coherent light) or light-emitting diodes (LEDs; noncoherent light), leading to the modulation of cellular functions, such as proliferation and migration, which result in tissue regeneration. PBM therapy has important clinical applications in regenerative medicine. Vitiligo is an acquired depigmentary disorder resulting from disappearance of functional melanocytes in the involved skin. Vitiligo repigmentation depends on available melanocytes derived from (a) melanocyte stem cells located in the bulge area of hair follicles and (b) the epidermis at the lesional borders, which contains a pool of functional melanocytes. Since follicular melanoblasts (MBs) are derived from the melanocyte stem cells residing at the bulge area of hair follicle, the process of vitiligo repigmentation presents a research model for studying the regenerative effect of PBM therapy. Previous reports have shown favourable response for treatment of vitiligo with a low-energy helium-neon (He-Ne) laser. This review focuses on the molecular events that took place during the repigmentation process of vitiligo triggered by He-Ne laser (632.8 nm, red light). Monochromatic radiation in the visible and infrared A (IRA) range sustains matrix metalloproteinase (MMP), improves mitochondrial function, and increases adenosine triphosphate (ATP) synthesis and O₂ consumption, which lead to cellular regenerative pathways. Cytochrome c oxidase in the mitochondria was reported to be the photoacceptor upon which He-Ne laser exerts its effects. Mitochondrial retrograde signalling is responsible for the cellular events by red light. This review shows that He-Ne laser initiated mitochondrial retrograde signalling via a Ca²⁺ -dependent cascade. The impact on cytochrome c oxidase within the mitochondria, an event that results in activation of CREB (cyclic-AMP response element binding protein)-related cascade, is responsible for the He-Ne laser promoting functional development at different stages of MBs and boosting functional melanocytes. He-Ne laser irradiation induced (a) melanocyte stem cell differentiation; (b) immature outer root sheath MB migration; (c) differentiated outer root sheath MB melanogenesis and migration; and (d) perilesional melanocyte migration and proliferation. These photobiomodulation effects result in perifollocular and marginal repigmentation in vitiligo.

Adenovirus 36 improves glycemic control and markers of Alzheimer's disease pathogenesis

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder worldwide. While the causes of AD are unclear, several risk factors have been identified, including impaired glycemic control, which significantly increases the risk of cognitive decline and AD. In vitro and in vivo studies show that human adenovirus 36 (Ad36) improves glycemic control by increasing cellular glucose uptake in cells, experimental animal models and in humans who are naturally exposed to the virus. This study, tested improvement in glycemic control by Ad36 and delay in onset of cognitive decline in APPswe transgenic mice (Tg2576 line), a model of genetic predisposition to impaired glycemic control and AD. Three-month old APPswe mice were divided into Ad36 infected (Ad36) or mock infected (control) groups and baseline glycemic control measured by glucose tolerance test (GTT) prior to infection. Changes in glycemic control were determined 10- and 24-week post infection. Serum insulin was also measured during GTT. Cognition was determined by Y-maze test, while motor coordination and skill acquisition by rotarod test. Glycemic control as determined by GTT showed less deterioration in Ad36 infected mice over time, accompanied by a significant attenuation of cognitive decline. Analysis of brain tissue lysate showed significantly reduced levels of amyloid beta 42 in Ad36 mice relative to control mice. Golgi-Cox staining analysis also revealed reduced dendritic spines and synaptic gene expression in control mice compared to Ad36 infected mice. This proof of concept study shows that in a mouse model of AD, Ad36 improves glycemic control and ameliorates cognitive decline.

Twenty-five years of research about adipogenic adenoviruses: A systematic review

Infectious etiology is implicated in chronic diseases such as gastric ulcer or atherosclerosis. However, "infection" is a recent term in the field of obesity. Since the first report in 1982 of obesity due to infection, several microbes have been linked to obesity. Among the adipogenic microbes, avian adenovirus SMAM-1 and human adenovirus Ad36 have been studied most extensively for the past 25 years. Here, we present a systematic review of literature about SMAM-1 and Ad36. Reports from North America, Europe, and Asia reveal strong evidence that Ad36 causes obesity in animals and paradoxically improves glycemic control, and in vitro data provides mechanistic explanation. Considering that experimental Ad36 infection of humans is unlikely, its causative role in human obesity or glycemic control has not been demonstrated unequivocally. Nonetheless, most, but not all, observational studies in children and adults link Ad36 infection to obesity and improvement in glycemic control. The E4orf1 gene of Ad36 was identified as responsible for better glycemic control. Overall, 25 years have considerably advanced knowledge about the role of infection in obesity. Potential translational benefits include the development of vaccines to prevent Ad36-induced obesity and drug development based on the E4orf1 protein to improve glycemic control.

Adenovirus 5 produces obesity and adverse metabolic, morphological, and functional changes in the long term in animals fed a balanced diet or a high-fat diet: a study on hamsters

Adenovirus 5 (Ad-5) infection is a common cause of acute respiratory infections and the main vector used in gene therapy. There are few studies on the relationship of Ad-5 to obesity. In the present study, we evaluated the chronic effects of Ad-5 infection on golden (Syrian) hamsters fed either a balanced diet (BD) or a high-fat diet (HFD). After a single inoculation with Ad-5 (1 × 10⁷ pfu), the body weight of the animals was measured weekly. Medium-term (22 weeks) serum biochemical analyses and long-term (44 weeks) liver morphology, adiposity, and locomotive functionality (movement velocity) assessments were carried out. In the animals fed the BD, adenovirus infection produced hyperglycemia and hyperlipidemia. In the long term, it produced a 57% increase in epididymal pad fat and a 30% body weight gain compared with uninoculated animals. In addition, morphological changes related to non-alcoholic fatty liver disease (NAFLD) were observed. The animals fed the HFD had similar but more severe changes. In addition, the hamsters presented an obesity paradox: at the end of the study, the animals that had the most morphological and functional changes (significantly reduced movement velocity) had the lowest body weight. Despite the fact that an HFD appears to be a more harmful factor in the long term than adenovirus infection alone, infection could increase the severity of harmful effects in individuals with an HFD. Epidemiological studies are needed to evaluate the effect of adenovirus as a precursor of chronic liver and cardiovascular diseases, including the chronic effects of gene therapy.

Adenovirus 36 seropositivity is related to obesity risk, glycemic control, and leptin levels in Chilean subjects

BACKGROUND

Adenovirus 36 (Ad-36) has been associated to adiposity in animal and in vitro studies. Ad-36 seropositivity has also been reported to contribute to obesity risk in children and adult populations. We investigated the relationship of Ad-36 serology with obesity and metabolic parameters in a Chilean population.

SUBJECTS AND METHODS

Clinical and anthropometric data were obtained and blood samples were drawn from 99 lean (BMI: 18.5-24.9 kg/m²) and 151 obese (BMI > 30 kg/m²) subjects. Laboratory tests included lipid profile as well as glucose, insulin, leptin, and adiponectin levels. Ad-36 seropositivity was evaluated in serum samples by enzyme-linked immunosorbent assay.

RESULTS

Seroprevalence of Ad-36 was higher in the obese group (58%) than in lean controls (34%) demonstrating that individuals previously infected with Ad-36 have higher risk of obesity in the study population (OR: 2.67, 95%CI: 1.58-4.51, p < 0.001). Interestingly, Ad-36 was related to lower concentrations of triglycerides and VLDL cholesterol in lean subjects (p = 0.049) and lower leptin in obese individuals (p = 0.014). Previous Ad-36 infection was also related to lower glycemia, insulinemia, and HOMA-IR (p < 0.05) in obese subjects who were not under antidiabetic drugs.

CONCLUSIONS

Our results provide evidence of the contribution of previous Ad-36 infection to an increased risk of obesity in adult Chilean population. Ad-36 seropositivity was also associated to lipid profile, glycemic control, and leptin levels in adult Chilean population.

High adenovirus 36 seroprevalence among a population of Hispanic American youth

Infection with adenovirus 36 (Ad36) has been associated with risk of obesity in youth in some studies, but the seroprevalence of this virus has not been examined among all populations. As Hispanic-American youth are of greater risk for obesity than other American youth, we sought to determine the proportion of Ad36 seropositive (Ad36+) students in an urban middle school serving a Hispanic population. We further examined if Ad36+ students were more likely to have obesity, and if Ad36 serostatus impacted changes in weight status following a health intervention. We determined body mass index (BMI) at the beginning and end of a 16-week health intervention among 40 Hispanic-American middle-school students. Ad36 serostatus was determined by enzyme-linked immunsorbent assay (ELISA). Seventy percent of the students were Ad36+. Ad36+ and Ad36 seronegative (Ad36-) did not differ before or after the intervention in body weight measures. The odds of being classified as obese was 1.4 times greater among Ad36+ than Ad36- at baseline, and 2.4 times greater post-intervention, but these were not statistically significant. We report a high seroprevalence of Ad36 among a population of Hispanic-American students. Ad36 seropositivity was associated with a trend for a greater likelihood of having obesity, but did not impact response to a health intervention.

Adipocyte biology: It is time to upgrade to a new model

Globally, the obesity pandemic is profoundly affecting quality of life and economic productivity, but efforts to address this, especially on a pharmacological level, have generally proven unsuccessful to date, serving as a stark demonstration that our understanding of adipocyte biology and pathophysiology is incomplete. To deliver better insight into adipocyte function and obesity, we need improved adipocyte models with a high degree of fidelity in representing the in vivo state and with a diverse range of experimental applications. Adipocyte cell lines, especially 3T3-L1 cells, have been used extensively over many years, but these are limited in terms of relevance and versatility. In this review, I propose that primary adipose-derived stromal/stem cells (ASCs) present a superior model with which to study adipocyte biology ex vivo. In particular, ASCs afford us the opportunity to study adipocytes from different, functionally distinct, adipose depots and to investigate, by means of in vivo/ex vivo studies, the effects of many different physiological and pathophysiological factors, such as age, body weight, hormonal status, diet and nutraceuticals, as well as disease and pharmacological treatments, on the biology of adipocytes and their precursors. This study will give an overview of the characteristics of ASCs and published studies utilizing ASCs, to highlight the areas where our knowledge is lacking. More comprehensive studies in primary ASCs will contribute to an improved understanding of adipose tissue, in healthy and dysfunctional states, which will enhance our efforts to more successfully manage and treat obesity.

Using rats as a research model to investigate the effect of human adenovirus 36 on weight gain

BACKGROUND

Recent evidence has shown a positive correlation between obesity and viral infections with a particular emphasis on the human adenovirus-36 (Ad-36). Ad-36 is the first human virus that may increase adiposity in animals, and it is considered as a possible risk factor for obesity in humans; however, the results were not consistent across all the studies. The present study was conducted to examine the influence of Ad-36 infection on obesity in a rat model.

METHODS

Eight-week-old male Wistar rats weighing 170-240 gram (g), were randomly divided into two groups, infection group (48 rats) and a control group (12 rats). The rats in the infection group were infected with human Ad-36. All rats were given free access to a normal chow diet and water. They were weighed weekly.

RESULTS

The mean ± standard deviation (SD) body weights were 229.0 ± 25.9 g and 232.3 ± 16.6 g in the infection and control groups, respectively at the time of infection. The mean ± SD body weight of the infection group (304.0 ± 39.0 g) was higher than the control group (301.0 ± 36.5 g) at 12 weeks post-infection (P = 0.82). Although two groups had approximately same food intakes, the mean change in body weight was greater in the infection group than the control group (75.8 ± 27.9 g vs. 70.8 ± 24.5 g) but it was not significant (P = 0.57).

CONCLUSION

We did not find a statistically significant association between weight gain and Ad-36 infection in the rat model. It seems that longer follow-up duration is needed to develop a significant weight gain in the infected rats. Rats can be used as a good animal model for further investigations about Ad-36-induced obesity, provided not to rely merely on weight measurements. Evaluating body composition or histopathological assessments are suggested.

Mouse adenovirus type 1 infection of adipose tissue

Human adenovirus (HAdV) type 36 seropositivity has been linked to obesity in humans. That link is supported by a small number of studies using HAdV-36 infection of animals that are not natural hosts for HAdVs. In this study, we infected mice with mouse adenovirus type 1 (MAV-1), a mouse pathogen, to determine whether MAV-1 infected adipose tissue and was associated with adipose tissue inflammation and obesity. We detected MAV-1 in adipose tissue during acute MAV-1 infection, but we did not detect virus-induced increases in adipose tissue cytokine expression or histological evidence of adipose tissue inflammation during acute infection. MAV-1 did not persist in adipose tissue at later times, and we did not detect long-term adipose inflammation, increased adipose tissue mass, or body weight in infected mice. Our data indicate that MAV-1 is not associated with obesity in infected mice.

Viral Infections and Obesity

PURPOSE OF REVIEW

Obesity is a multifactorial disease that is now endemic throughout most of the world. Although addressing proximate causes of obesity (excess energy intake and reduced energy expenditure) have been longstanding global health priorities, the problem has continued to worsen at the global level.

RECENT FINDINGS

Numerous microbial agents cause obesity in various experimental models-a phenomena known as infectobesity. Several of the same agents alter metabolic function in human cells and are associated with human obesity or metabolic dysfunction in humans. We address the evidence for a role in the genesis of obesity for viral agents in five broad categories: adenoviridae, herpesviridae, phages, transmissible spongiform encephalopathies (slow virus), and other encephalitides and hepatitides. Despite the importance of this topic area, there are many persistent knowledge gaps that need to be resolved. We discuss factors motivating further research and recommend that future infectobesity investigation should be more comprehensive, leveraged, interventional, and patient-centered.

Metformin Is Associated With Higher Relative Abundance of Mucin-Degrading Akkermansia muciniphila and Several Short-Chain Fatty Acid-Producing Microbiota in the Gut

The global obesity epidemic, dubbed “globesity” by the World Health Organisation, is a pressing public health issue. The aetiology of obesity is multifactorial incorporating both genetic and environmental factors. Recently, epidemiological studies have observed an association between microbes and obesity. Obesity-promoting microbiome and resultant gut barrier disintegration have been implicated as key factors facilitating metabolic endotoxaemia. This is an influx of bacterial endotoxins into the systemic circulation, believed to underpin obesity pathogenesis. Adipocyte dysfunction and subsequent adipokine secretion characterised by low grade inflammation, were conventionally attributed to persistent hyperlipidaemia. They were thought of as pivotal in perpetuating obesity. It is now debated whether infection and endotoxaemia are also implicated in initiating and perpetuating low grade inflammation. The fact that obesity has a prevalence of over 600 million and serves as a risk factor for chronic diseases including cardiovascular disease and type 2 diabetes mellitus is testament to the importance of exploring the role of microbes in obesity pathobiology. It is on this basis that Massachusetts General Hospital is sponsoring the Faecal Microbiota Transplant for Obesity and Metabolism clinical trial, to study the impact of microbiome composition on weight. The association of microbes with obesity, namely, adenovirus infection and metabolic endotoxaemia, is reviewed.

Adenovirus 36 antibody detection: Improving the standard serum neutralization assay

Adenovirus 36 (AdV36) causes weight gain in animal models, including non-human primates. In humans, AdV36-neutralizing antibodies are associated with adiposity; however, longitudinal studies in large populations are needed to clarify AdV36's contribution. The current gold standard for detection of AdV36-specific antibody is the serum neutralization assay (SNA), which requires long incubation times and highly trained personnel. The standard SNA was modified using an immunocytochemical (ICC) approach, which allows for a more rapid and objective assessment of AdV36 antibodies. Using the ICC assay, virus-infected cells were detected as early as day 1 (D1) and by D5 were detected in 100% of microtiter wells versus 20.3% of wells detected by observing the cytopathic effect. Further, human sera tested with the ICC assay at D5 had a sensitivity and specificity of 80.0% and 95.7%, respectively, when compared to the standard SNA read at D11. Thus, the ICC assay decreased assay incubation time, provided a more objective and easily interpreted assessment, and had a high degree of sensitivity and specificity in determining serological status. The more rapid and objective ICC method will make large population studies feasible, improve comparability among laboratories, and contribute to understanding the role of AdV36 in obesity.

Infectobesity: the evaluation of adenovirus-36 infection and obesity

Obesity, which causes some cancer types and other diseases, is not only a global public health problem, but also a factor that affects country's economy. Endocrinal, environmental, neuronal and genetic factors have important roles on the etiology of obesity. When the possibility that SMAM‐1 animal virus could have a relationship with obesity was observed, obesity studies focused on human adenoviruses. Adenovirus‐36 was first isolated in 1978 and was the first human adenovirus to be tested in terms of infectobesity. Both in vivo and in vitro studies proved the strong relationship between adenovirus‐36 presence and obesity. Therefore, a large-scale study incorporating various ethnicities and age groups is required to investigate the worldwide epidemic of obesity and its links with viruses.

Human Adenovirus 36 Infection Increased the Risk of Obesity: A Meta-Analysis Update

Human adenovirus 36 (HAdV-36), as the key pathogen, was supposed and discussed to be associated with obesity. We searched the references on the association between HAdV-36 infection and obesity with the different epidemiological methods, to explore the relationship with a larger sample size by meta-analysis and compare the differences of epidemiological methods and population subsets by the subgroup analyses.We conducted literature search on the association between HAdV-36 infections and obesity in English or Chinese published up to July 1, 2015. The primary outcome was the HAdV-36 infection rate in the obese and lean groups; the secondary outcomes were the BMI level and BMI z-score in the HAdV-36 positive and negative groups. The pooled odds ratio (OR) was calculated for the primary outcome; the standardized mean differences (SMDs) were calculated for the secondary and third outcomes. Prediction interval (PI) was graphically presented in the forest plot of the random effect meta-analyses. Metaregression analysis and subgroup analysis were performed.Finally 24 references with 10,191 study subjects were included in the meta-analysis. The obesity subjects were more likely to be infected with HAdV-36 compared to the lean controls (OR = 2.00; 95%CI: 1.46, 2.74; PI: 0.59, 6.76; P < 0.001) with a high heterogeneity (I = 80.1%; P < 0.001) estimated by the random effect model. Subgroup analysis demonstrated that the pooled OR of HAdV-36 infection for obesity were 1.77 (95%CI: 1.19, 2.63; PI: 0.44, 7.03; P = 0.005) and 2.26 (95%CI: 1.67, 3.07; PI: 1.45, 3.54; P < 0.001) in the adults and children, respectively. Compared to the HAdV-36 negative subjects, the SMD of BMI was 0.28 (95% CI: 0.08, 0.47; PI: -0.53, 1.08; P = 0.006) in the HAdV-36 positive subjects with a high heterogeneity (I = 86.5%; P < 0.001). The BMI z-score in the children with HAdV-36 infection was higher than those without HAdV-36 infection (SMD = 0.19; 95%CI: -0.31, 0.70; PI: -2.10, 2.49), which had no significantly statistical difference (P = 0.453).HAdV-36 infection increased the risk of obesity. HAdV-36 also increased the risk of weight gain in adults, which was not observed in children.

Association of Adenovirus 36 Infection With Obesity-Related Gene Variants in Adolescents

Both, common gene variants and human adenovirus 36 (Adv36) are involved in the pathogenesis of obesity. The potential relationship between these two pathogenic factors has not yet been investigated. The aim of our study was to examine the association of obesity susceptibility loci with Adv36 status. Genotyping of ten gene variants (in/near TMEM18, SH2B1, KCTD15, PCSK1, BDNF, SEC16B, MC4R, FTO) and analysis of Adv36 antibodies was performed in 1,027 Czech adolescents aged 13.0-17.9 years. Variants of two genes (PCSK1 and BDNF) were associated with Adv36 seropositivity. A higher prevalence of Adv36 antibody positivity was observed in obesity risk allele carriers of PCSK1 rs6232, rs6235 and BDNF rs4923461 vs. non-carriers (χ2=6.59, p=0.010; χ2=7.56, p=0.023 and χ2=6.84, p=0.033, respectively). The increased risk of Adv36 positivity was also found in PCSK1 variants: rs6232 (OR=1.67, 95 % CI 1.11-2.49, p=0.016) and rs6235 (OR=1.34, 95 % CI 1.08-1.67, p=0.010). PCSK1 rs6232 and BDNF rs925946 variants were closely associated with Adv36 status in boys and girls, respectively (χ2=5.09, p=0.024; χ2=7.29, p=0.026). Furthermore, PCSK1 rs6235 risk allele was related to Adv36 seropositivity (χ2=6.85, p=0.033) in overweight/obese subgroup. In conclusion, our results suggest that obesity risk variants of PCSK1 and BDNF genes may be related to Adv36 infection.

Obesity and Infection: Reciprocal Causality

Associations between different infectious agents and obesity have been reported in humans for over thirty years. In many cases, as in nosocomial infections, this relationship reflects the greater susceptibility of obese individuals to infection due to impaired immunity. In such cases, the infection is not related to obesity as a causal factor but represents a complication of obesity. In contrast, several infections have been suggested as potential causal factors in human obesity. However, evidence of a causal linkage to human obesity has only been provided for adenovirus 36 (Adv36). This virus activates lipogenic and proinflammatory pathways in adipose tissue, improves insulin sensitivity, lipid profile and hepatic steatosis. The E4orf1 gene of Adv36 exerts insulin senzitizing effects, but is devoid of its pro-inflammatory modalities. The development of a vaccine to prevent Adv36-induced obesity or the use of E4orf1 as a ligand for novel antidiabetic drugs could open new horizons in the prophylaxis and treatment of obesity and diabetes. More experimental and clinical studies are needed to elucidate the mutual relations between infection and obesity, identify additional infectious agents causing human obesity, as well as define the conditions that predispose obese individuals to specific infections.

The role of Ad-36 as a risk factor in males with gynecomastia

Gynecomastia is highly prevalent worldwide and Adenovirus-36 (Ad-36), recently implicated in increased adipose tissue deposition due to its affinity for adipose tissue, is a potential etiological agent in the development of obesity and therefore we hypothesized that Ad-36 may also play a role in the development of gynecomastia by possibly accompanying increased regional adiposity. To support our hypothesis, we conducted a study that included 33 adult males with gynecomastia (PG) and 15 adult males as the patient control group (HCG). Leptin and adiponectin levels were monitored using ELISA. A significant difference in Ad-36 antibody positivity was found between the groups (p<0.05). Average leptin levels were found to be higher, but average adiponectin levels were found to be lower in Ad-36 Ab(+) patient group. No Ad-36 DNA was detected in any tissue samples. In conclusion, we hypothesize that low-grade chronic inflammation, which was caused by Ad-36 infection, possibly caused an increase in circulating leptin. This in turn may have caused an increase in local or circulating estrogens and/or the estrogen/androgen ratio by stimulating the aromatase enzyme activity in adipose stromal cells and breast tissues. We suggest that gynecomastia may develop following an increase in aromatase enzyme activity, by which more oestrogen is produced and the estrogen-androgen balance disrupted. Also, regional adipose tissue enlargements may cause the excessive production of estrogens leading to gynecomastia. Adipose tissue has been recognized as a major endocrine organ in recent years. Another plausible explanation is excessive aromatization of androgens to estrogens by peripheral adipose tissue may promote gynecomastia in males. Moreover, our results suggest that there might be a relationship between Ad-36 and gynecomastia.

Role of adenoviruses in obesity

Five human adenovirus subtypes, Ad5, Ad9, Ad31, Ad36, and Ad37, and a non-human adenovirus, SMAM1, are linked to increased adiposity in vitro or in vivo. Experimental infection with Ad5, Ad36, and Ad37 produced excess adiposity or weight gain in animals. Ad9 and Ad31 increase fat storage in tissue culture but are not associated with animal or human obesity. Ad36 is the most extensively studied adipogenic adenovirus and is correlated with some measure of overweight/obesity in humans from multiple countries. The correlation is strongest and most consistent in children, but some studies have been negative in both children and adults. About 30% of overweight/obese children and adults and about 15-20% of lean individuals have Ad36 antibodies in epidemiologic studies. The mechanisms of action of Ad36 are due to the early gene 4, open reading frame 1 (E4-ORF1). Blocking E4-ORF1 with siRNA prevents the effects of Ad36, and transfection of lentivirus with E4-ORF1 reproduces the Ad36 effects. Increased adiposity is caused by stimulation of at least three pathways by Ad36. Cell membrane glucose receptors are increased via the Ras pathway, leading to increased intracellular glucose. Fatty acid synthase is increased, which converts the glucose to fatty acids. Finally, peroxisome proliferator-activated receptor-γ is increased, resulting in differentiation of adult stem cells into adipocytes.

CONCLUSIONS

several adenoviruses increase adiposity in animals and are associated with obesity in humans. There are critical gaps in the literature needing further investigation including evaluation of other adenovirus subtypes and better research designs to improve the strength of causal inferences.

Adenovirus 36 DNA in human adipose tissue

Recent studies have suggested a possible correlation between obesity and adenovirus 36 (Adv36) infection in humans. As information on adenoviral DNA presence in human adipose tissue are limited, we evaluated the presence of Adv36 DNA in adipose tissue of 21 adult overweight or obese patients. Total DNA was extracted from adipose tissue biopsies. Virus detection was performed using PCR protocols with primers against specific Adv36 fiber protein and the viral oncogenic E4orf1 protein nucleotide sequences. Sequences were aligned with the NCBI database and phylogenetic analyses were carried out with MEGA6 software. Adv36 DNA was found in four samples (19%). This study indicates that some individuals carry Adv36 in the visceral adipose tissue. Further studies are needed to determine the specific effect of Adv36 infection on adipocytes, the prevalence of Adv36 infection and its relationship with obesity in the perspective of developing a vaccine that could potentially prevent or mitigate infection.

Adenovirus 36 and Obesity: An Overview

There is an epidemic of obesity starting about 1980 in both developed and undeveloped countries definitely associated with multiple etiologies. About 670 million people worldwide are obese. The incidence of obesity has increased in all age groups, including children. Obesity causes numerous diseases and the interaction between genetic, metabolic, social, cultural and environmental factors are possible cofactors for the development of obesity. Evidence emerging over the last 20 years supports the hypothesis that viral infections may be associated with obesity in animals and humans. The most widely studied infectious agent possibly linked to obesity is adenovirus 36 (Adv36). Adv36 causes obesity in animals. In humans, Adv36 associates with obesity both in adults and children and the prevalence of Adv36 increases in relation to the body mass index. In vivo and in vitro studies have shown that the viral E4orf1 protein (early region 4 open reading frame 1, Adv) mediates the Adv36 effect including its adipogenic potential. The Adv36 infection should therefore be considered as a possible risk factor for obesity and could be a potential new therapeutic target in addition to an original way to understand the worldwide rise of the epidemic of obesity. Here, the data indicating a possible link between viral infection and obesity with a particular emphasis to the Adv36 will be reviewed.

The relationship between adenovirus-36 seropositivity, obesity and metabolic profile in Turkish children and adults

Obesity potentially arising from viral infection is known as 'infectobesity'. The latest reports suggest that adenovirus-36 (Adv36) is related to obesity in adults and children. Our aim was not only to determine the Adv36 seropositivity in both obese and non-obese children and adults, but also to investigate correlations between antibody positivity and serum lipid profiles. Both Adv36 positivity and tumour-necrosis-factor-alpha, leptin and interleukin-6 levels were detected in blood samples collected from 146 children and 130 adults by ELISA. Fasting plasma triglycerides, total cholesterol and low-density lipoprotein levels were also measured. Adv36 positivity was determined to be 27·1% and 6% in obese and non-obese children and 17·5% and 4% in obese and non-obese adults, respectively. There was no difference with regard to total cholesterol, low-density lipoprotein, triglyceride, tumour-necrosis-factor-alpha and interleukin-6 levels (P > 0·05). However, there was a significant difference between groups in terms of leptin levels (P < 0·05). We determined the prevalence of Adv36 positivity in obese children and adults. Our results showed that Adv36 may be an obesity agent for both adults and children, parallel with current literature data. However, the available data on a possible relationship between Adv36 infection and obesity both in children and adults do not completely solve the problem.

The role of adenovirus 36 as a risk factor in obesity: the first clinical study made in the fatty tissues of adults in Turkey

Obesity which developes due to multifactorial reasons, was associated recently with human Adenovirus-36 (Ad-36). The aim of this study was to investigate the prevalence of Ad-36 antibodies in obese adults and also to investigate the DNA of Ad-36 in their adipose tissue. In this cross-sectional and case-control based study, 49 obese adults, with BMI ≥ 30 kg/m(2), and 49 non-obese adults, with BMI ≤ 25 kg/m(2), applied for esthetic purposes and were included in this study as patient and control groups, respectively. Adipose tissue samples, obtained by the lipoaspiration method, were studied by single-step PCR and nested-PCR methods. Simultaneously, the presence of Ad-36 antibodies and serum leptin and adiponectin levels were assessed by serum neutralization assay (SNA) and ELISA, respectively. Serum samples which didn't cause a cytopathic effect at ≥ 1:8 were accepted as positive. Ad-36 antibody was detected in 6 (12.2%) of 49 patients by SNA and was statistically significant (p < 0.05). Ad-36 DNA was not detected in any of the adipose tissue samples of the patient or control groups. Mean BMI and leptin levels were higher in the Ad-36-positive group, while adiponectin levels were found to be lower in the Ad-36-positive group. Although no statistically significant difference was found in cholesterol and triglyceride levels between the two groups (p > 0.05), lower mean serum cholesterol and triglyceride levels were found in the Ad-36-positive patients. In conclusion, we couldn't detect Ad-36 DNA in adipose tissue; however, we detected significantly higher Ad-36 antibody levels in the obese group compared to the non-obese group, according to the both univariant and multivariant analyses, suggesting that Ad-36 may play a role in obesity. There is a need for new and extended serial, particularly cohort and human-based, studies in order to have a clear understanding of the Ad-36-obesity relationship.

Adenovirus 36 attenuates weight loss from exercise but improves glycemic control by increasing mitochondrial activity in the liver

Human adenovirus type 36 (Ad36) as an obesity agent induces adiposity by increasing glucose uptake and promoting chronic inflammation in fat tissues; in contrast, exercise reduces total body fat and inflammation. Our objective was to determine the association between Ad36 and the effects of exercise on inflammation and glycemic control. In the human trials (n = 54), Korean children (aged 12–14 years) exercised for 60 min on three occasions each week for 2 months. We compared the body mass index (BMI) Z-scores before and after exercise. C57BL/6 mice were infected with Ad36 and Ad2 as a control, and these mice exercised for 12 weeks postinfection. After the exercise period, we determined the serum parameters and assessed the presence of inflammation and the mitochondrial function in the organs. Ad36-seropositive children who were subjected to a supervised exercise regimen had high BMI Z-scores whereas Ad36-seronegative children had lower scores. Similarly, Ad36-infected mice were resistant to weight loss and exhibited chronic inflammation of their adipose tissues despite frequent exercise. However, Ad36 combined with exercise reduced the levels of serum glucose, nonesterified fatty acids, total cholesterol, and insulin in virus-infected mice. Interestingly, virus infection increased the mitochondrial function in the liver, as demonstrated by the numbers of mitochondria, cytochrome c oxidase activity, and transcription of key mitochondrial genes. Therefore Ad36 counteracts the weight-loss effect of exercise and maintains the chronic inflammatory state, but glycemic control is improved by exercise synergistically because of increased mitochondrial activity in the liver.

Human adenovirus-36 is uncommon in type 2 diabetes and is associated with increased insulin sensitivity in adults in Sweden

BACKGROUND

Human adenovirus-36 (Adv36) increases adiposity, but also upregulates distal insulin signaling in vitro in human adipose and muscle tissue and in vivo in the rodent independently of adiposity. Accordingly, healthy adults and children with antibodies against Adv36 had increased insulin sensitivity and reduced hepatic lipid accumulation. We hypothesized that Adv36 infection would be less frequent in individuals with type 2 diabetes or impaired glycemic control.

METHODS

Presence of antibodies against Adv36 was analyzed for association to type 2 diabetes or impaired glycemic control in a two-wave population-based sample of well-characterized adults (n = 1734). Indices of impaired glycemic control included oral glucose tolerance, and circulating fasting levels of glucose, insulin, and insulin-like growth factor binding protein-1 (IGFBP-1).

RESULTS

Adv36 seropositivity was more common in those with normal glucose tolerance (NGT) than in those with diabetes (females: OR 17.2, 95% CI 4.0-74.3; males: OR 3.5, 95% CI 1.8-6.7). Also, females with NGT had higher frequency of Adv36 seropositivity than females with prediabetes (impaired glucose tolerance and/or impaired fasting glucose; OR 1.8, 95% CI 1.1-3.1). Within the female prediabetes group Adv36 seropositivity was associated with higher insulin sensitivity reflected by reduced HOMA-IR and increased IGFBP-1.

CONCLUSION

Adv36 infection is associated with lower occurrence of type 2 diabetes and better insulin sensitivity in adults, particularly among females.

ADV36 adipogenic adenovirus in human liver disease

Obesity and liver steatosis are usually described as related diseases. Obesity is regarded as exclusive consequence of an imbalance between food intake and physical exercise, modulated by endocrine and genetic factors. Non-alcoholic fatty liver disease (NAFLD), is a condition whose natural history is related to, but not completely explained by over-nutrition, obesity and insulin resistance. There is evidence that environmental infections, and notably adipogenic adenoviruses (ADV) infections in humans, are associated not only with obesity, which is sufficiently established, but also with allied conditions, such as fatty liver. In order to elucidate the role, if any, of previous ADV36 infection in humans, we investigated association of ADV36-ADV37 seropositivity with obesity and fatty liver in humans. Moreover, the possibility that lifestyle-nutritional intervention in patients with NAFLD and different ADV36 seropositive status, achieves different clinical outcomes on ultrasound bright liver imaging, insulin resistance and obesity was challenged. ADV36 seropositive patients have a more consistent decrease in insulin resistance, fatty liver severity and body weight in comparison with ADV36 seronegative patients, indicating a greater responsiveness to nutritional intervention. These effects were not dependent on a greater pre-interventional body weight and older age. These results imply that no obvious disadvantage - and, seemingly, that some benefit - is linked to ADV36 seropositivity, at least in NAFLD. ADV36 previous infection can boost weight loss and recovery of insulin sensitivity under interventional treatment.

Association of adenovirus 36 infection with adiposity and inflammatory-related markers in children

CONTEXT

Although animal studies suggest that adenovirus 36 (Ad36) infection is linked to obesity and systemic inflammation, human data are scant and equivocal.

OBJECTIVE

Associations of Ad36 infection with total body adiposity and inflammatory-related markers were determined in 291 children aged 9-13 years (50% female, 49% black).

DESIGN

Fasting blood samples were measured for presence of Ad36-specific antibodies and TNF-α, IL-6, vascular endothelial growth factor (VEGF), and monocyte chemoattractant protein-1 (MCP-1). Fat mass and fat-free soft tissue mass were measured by dual-energy X-ray absorptiometry.

RESULTS

The overall prevalence of Ad36 seropositivity [Ad36(+)] was 42%. There was a higher percentage of Ad36(+) children in the highest tertiles of TNF-α and IL-6 compared with their respective middle and lowest tertiles (both P < .03). There was also a trend toward a higher prevalence of Ad36(+) children in the highest tertile of VEGF compared with tertiles 1 and 2 (P = .05). Multinomial logistic regression, adjusting for age, race, sex, and fat-free soft tissue mass, revealed that compared with children with the lowest TNF-α, IL-6, and VEGF levels (tertile 1), the adjusted odds ratios for Ad36(+) were 2.2 [95% confidence interval (CI) 1.2-4.0], 2.4 (95% CI 1.4-4.0), and 1.8 (95% CI 1.0-3.3), respectively, for those in the highest TNF-α, IL-6, and VEGF levels (tertile 3). No association was observed between Ad36(+) and greater levels of fat mass or MCP-1 (all P > .05).

CONCLUSIONS

In children, our data suggest that Ad36(+) may be associated with biomarkers implicated in inflammation but not with greater levels of fat mass.

Adenovirus36 infection expresses cellular APMI and Visfatin genes in overweight Uygur individuals

Objective

This study is to determine if Adenovirus type 36 (Ad36) infection is related to macrophage infiltration in the obese group and non-obese group and the related molecular mechanisms.

Methods

Ninety obesity patients and 95 non-obesity Uygur individuals were enrolled in this study. CD68 levels in abdominal subcutaneous and omental adipose tissues were detected by immunohistochemistry. The cytokine expression levels of adiponectin (APMI) and visfatin in serum were measured by enzyme-linked immunosorbent assay. Infection of 3T3-L1 cells with Ad36 was performed. Real-time PCR was performed to determine expression levels of APMI and Visfatin genes in the 3T3-L1 preadipocytes infected with Ad36.

Results

In the obese individuals infected with Ad36, the expression levels of adiponectin and visfatin in serum was elevated. For the individuals infected with Ad36, the macrophage infiltration (as indicated by CD68 level) in the obese group was also significantly higher than that in the non-obese group (P < 0.05) in both abdominal subcutaneous and omental adipose tissues. The real-time PCR results indicated that APMI mRNA levels and Visfatin mRNA levels in Ad36 infected cells were significantly increased.

Conclusions

Ad36 infection may be a factor related with macrophage infiltration in adipose tissues of the obese patients. The APMI and Visfatin genes may be involved in the mechanism underlying the effect of Ad36 infection on the obese patients.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1849614638119816

Serological data analyses show that adenovirus 36 infection is associated with obesity: a meta-analysis involving 5739 subjects

OBJECTIVE

Serological studies on the relationship between adenovirus 36 (Ad36) and an increased risk of obesity development have shown conflicting results. We reviewed the published studies and carried out a meta-analysis to explore this relationship.

METHODS

PubMed was searched until December 2012 for the relative references with sufficient information to estimate odds ratios (ORs) and 95% confidence intervals (CIs). A total of 11 case-control studies, including 2508 obese subjects and 3005 controls, were selected.

RESULTS

Compared with nonobese controls, Ad36 infection significantly increased the obesity risk by a pooled OR of 1.60 (95% CI = 1.14-2.25; P < 0.01). Meta-regression showed that the types of subject and obesity assessments were potential risk factors. In the subgroup analysis, a significantly increased risk was found in children (OR = 1.95; 95% CI = 1.34-2.85; z = 3.45; P < 0.01) and those with an obesity assessment of BMI ≥ 30 kg/cm2 (OR = 1.89; 95% CI = 1.15-3.10; P < 0.05).

CONCLUSIONS

Ad36 infection is associated with an increased risk of obesity development. To our knowledge, this is the first report to reveal the significant relationship in children with a serological data analysis.

Obesity and infection: two sides of one coin

The prevalence of obesity has exponentially risen worldwide. The etiology of obesity is multifactorial, and genetic inheritance and behavioral/environmental causes are considered the main etiological factors. Moreover, evidence that specific infections might promote the development of obesity has steadily accumulated. Only a few works investigate the impact of obesity on the immune response to infections and the risk of infections in the obese population. The aim of this paper was to review the available data regarding the various aspects of the association between obesity and infections and to highlight the possibility that infectious agents may have an etiological role in obesity, an idea known as "infectobesity". Several microbes have been considered as possible promoter of obesity, but most of the data concern adenovirus-36 that exerts an adipogenic action mainly via a direct effect on adipose tissue leading to weight gain, at least in animal models.Obesity affects the immune response leading to an increased susceptibility to infections. Obese adults and children show an increased incidence of both nosocomial and community-acquired infections. Furthermore, obesity may alter the pharmacokinetics of antimicrobial drugs and impact on vaccine response. However, the various aspects of the association of obesity infections remain poorly studied, and a call to research is necessary to better investigate the problem.In conclusion, obesity impacts millions globally, and greater understanding of its etiology and its effects on immunity, infections, and prevention and management strategies is a key public health concern.

Effect of adenovirus and influenza virus infection on obesity

The purpose of this review is to provide an overview of the effects of adenovirus and influenza virus infections on obesity in various experimental models. We reviewed studies that were conducted within the past 10 years and were related to virus infection and obesity prevalence. Here, we discuss a different causal relationship between adenovirus and influenza infections with obesity. Adenovirus infection can cause obesity, whereas obesity can be a risk factor for increasing influenza virus infection and increases the risk of morbidity and mortality. The prevalence of obesity due to adenovirus infections may be due to an increase in glucose uptake and reduction in lipolysis caused by an increase in corticosterone secretion. Adenovirus infections may lead to increases in appetite by decreasing norepinephrine and leptin levels and also cause immune dysfunction. The relationship between obesity and influenza virus infection could be summarized by the following features: decreases in memory T-cell functionality and interferon (IFN)-α, IFN-β, and IFN-γ mRNA expression, increases in viral titer and infiltration, and impaired dendritic cell function in obese individuals. Moreover, leptin resistance may play an important role in increasing influenza virus infections in obese individuals. In conclusion, prevention of adenovirus infections could be a good approach for reducing obesity prevalence, and prevention of obesity could reduce influenza virus infections from the point of view of viral infections and obesity.

Harnessing the beneficial properties of adipogenic microbes for improving human health

Obesity is associated with numerous metabolic comorbidities. Weight loss is an effective measure for alleviating many of these metabolic abnormalities. However, considering the limited success of most medical weight-management approaches in producing a sustained weight loss, approaches that improve obesity-related metabolic abnormalities independent of weight loss would be extremely attractive and of practical benefit. Metabolically healthy obesity supports the notion that a better metabolic profile is possible despite obesity. Moreover, adequate expansion of adipose tissue appears to confer protection from obesity-induced metabolic comorbidities. To this end, the 10th Stock conference examined new approaches to improve metabolic comorbidities independent of weight loss. In particular, human adenovirus 36 (Ad36) and specific gut microbes were examined for their potential to influence lipid and glucose homeostasis in animals and humans. While these microbes possess some undesirable properties, research has identified attributes of adenovirus Ad36 and gut microbes that may be selectively harnessed to improve metabolic profile without the obligatory weight loss. Furthermore, identifying the host signalling pathways that these microbes recruit to improve the metabolic profile may offer new templates and targets, which may facilitate the development of novel treatment strategies for obesity-related metabolic conditions.

Investigation of adipogenic effects of human adenovirus serotypes 36 and 5 in a Colo-320 cell line

Aim: We aimed to investigate the adipogenic effects of adenovirus (Ad) serotypes 5, 36 and 8 in a Colo-320 cell line using histochemical, immunohistochemical and electron microscopic methods. Materials & methods: Ad serotypes were inoculated in a Colo-320 cell line and were cultured for 14 days. They were then collected and fixed with 4% paraformaldehyde to analyze their adipogenic effects using histochemistry, immunohistochemistry and electron microscopic methods. Intracellular lipid droplets were detected in the Colo-320 cells inoculated with Ad36 and Ad5 by electron microscopic analyses. Results: After Oil Red O staining, the pink–orange staining was positive intracellularly in Colo-320 cells infected with Ad36 and Ad5. In addition, the leptin immunoreactivity was also positive in these cells. Conclusion: Our results suggested that intracellular lipid accumulation occured after infection with Ad36 and Ad5. The positive staining of Oil Red O and leptin also supported the electron microscopic results; therefore, we conclude that this accumulation occurred due to adipogenic effects of Ad36 and Ad5.

Clinical and laboratory characteristics of 1179 Czech adolescents evaluated for antibodies to human adenovirus 36

BACKGROUND

Human adenovirus 36 (Adv36) is associated with obesity in children. Most prior studies have been small and the association of Adv36 status with markers of metabolic risks has been inconsistent.

OBJECTIVES

To determine the prevalence of Adv36 antibodies in different weight categories of adolescents and to evaluate the association of Adv36 infection with anthropometric parameters and cardiometabolic health risks.

SUBJECTS AND METHODS

In 1179 Czech adolescents (85 underweight, 506 normal weight, 160 overweight and 428 obese), the following variables were evaluated: anthropometric (body weight, height, body mass index, circumferences, fat mass), blood pressure, biochemical and hormonal (lipid profile, glucose, insulin, liver enzymes, adiponectin) and Adv36 antibodies (enzyme-linked immunosorbent assay).

RESULTS

Of the total cohort, 26.5% were positive for Adv36 antibodies (underweight: 22.3%; normal weight: 21.5%; overweight: 40.0% and obese: 28.0%). The odds ratio for Adv36 antibody positivity evaluated vs normal weight was 2.61 for overweight (95% confidence interval (CI): 1.77-3.86, P<0.001) and 1.46 for obesity (95% CI: 1.07-1.99, P=0.016). A significantly higher prevalence of Adv36 infection was observed in female subjects (32.5%) in comparison to male subjects (19.7%; P<0.001). Adv36 positivity of the whole cohort was significantly related to body weight (P=0.042), body mass index (P=0.015), hip circumference (P=0.004), body height z-score (P=0.029), and total body fat (P=0.000) and trunk fat (P=0.000). Adv36 antibody-positive girls demonstrated significantly higher body height (167.8 vs 165.0 cm, P=0.01) and waist circumference (77.0 vs 72.0 cm, P=0.01). Infected adolescents exhibited significantly higher levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), but lower levels of blood glucose. Liver enzymes were significantly increased only in Adv36-positive boys.

CONCLUSION

These results demonstrated an association of Adv36 antibodies with obesity and an even greater association with overweight. Adv36 positivity was related to increased fat mass, levels of TC and LDL-C, but to decreased level of blood glucose. No relation to adiponectin levels was revealed.