Hyperglycemia in acute COVID-19 is characterized by insulin resistance and adipose tissue infectivity by SARS-CoV-2

GRP78, a Novel Host Factor for SARS-CoV-2: The Emerging Roles in COVID-19 Related to Metabolic Risk Factors

The outbreak of coronavirus disease 19 (COVID-19), caused by the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in an unprecedented amount of infection cases and deaths, leading to the global health crisis. Despite many research efforts, our understanding of COVID-19 remains elusive. Recent studies have suggested that cell surface glucose-regulated protein 78 (GRP78) acts as a host co-receptor for SARS-CoV-2 infection and is related to COVID-19 risks, such as older age, obesity, and diabetes. Given its significance in a wide range of biological processes, such as protein homeostasis and cellular signaling, GRP78 might also play an important role in various stages of the viral life cycle and pathology of SARS-CoV-2. In this perspective, we explore the emerging and potential roles of GRP78 in SARS-CoV-2 infection. Additionally, we discuss the association with COVID-19 risks and symptoms. We hope this review article will be helpful to understand COVID-19 pathology and promote attention and study of GRP78 from many clinical and basic research fields.

Pancreatic Islets as a Target of Adipokines

Rising rates of obesity are intricately tied to the type 2 diabetes epidemic. The adipose tissues can play a central role in protection against or triggering metabolic diseases through the secretion of adipokines. Many adipokines may improve peripheral insulin sensitivity through a variety of mechanisms, thereby indirectly reducing the strain on beta cells and thus improving their viability and functionality. Such effects will not be the focus of this article. Rather, we will focus on adipocyte-secreted molecules that have a direct effect on pancreatic islets. By their nature, adipokines represent potential druggable targets that can reach the islets and improve beta-cell function or preserve beta cells in the face of metabolic stress. © 2022 American Physiological Society. Compr Physiol 12:1-27, 2022.

Anti-spike protein antibody responses to BNT162b2 mRNA vaccine: A single-center survey in a COVID-19 non-epidemic area in Japan

•

Anti-spike protein antibody concentration was elevated by BNT162b2 vaccination.

•

In a non-epidemic area, two BNT162b2 vaccine doses elicited good antibody responses.

•

The seroconversion rate was 99.7%.

•

Antibody responses to BNT162b2 in Asian females were higher than Asian males.

Background

There are a few reports on antibody responses after a two-dose BNT162b2 vaccination in non-epidemic areas. We evaluated this phenomenon.

Methods

A total of 344 healthcare workers were vaccinated, and the serum anti-receptor-binding domain (RBD) antibody concentrations before and after two weeks following the two-dose BNT162b2 vaccination were measured using electro chemiluminescence immunoassay system.

Results

Before vaccination, the antibody titers of all participants were less than 0.6 U/mL. After two doses of the BNT162b2 vaccine injection in 342 participants (2 excluded), a high seroconversion rate (99.7%) was observed. The average (±standard deviation) serum anti-RBD antibody titers were 2324 ± 1739 U/mL. Antibody levels in females and males were 2443 ± 1833 U/mL and 1908 ± 1287 U/mL, respectively (p = 0.037).

Conclusion

In a non-epidemic area, two BNT162b2 doses induced a satisfactory antibody response, and the antibody concentrations in females were higher than in males.

Metformin: Is it a drug for all reasons and diseases?

Metformin was first used to treat type 2 diabetes in the late 1950s and in 2022 remains the first-choice drug used daily by approximately 150 million people. An accumulation of positive pre-clinical and clinical data has stimulated interest in re-purposing metformin to treat a variety of diseases including COVID-19. In polycystic ovary syndrome metformin improves insulin sensitivity. In type 1 diabetes metformin may help reduce the insulin dose. Meta-analysis and data from pre-clinical and clinical studies link metformin to a reduction in the incidence of cancer. Clinical trials, including MILES (Metformin In Longevity Study), and TAME (Targeting Aging with Metformin), have been designed to determine if metformin can offset aging and extend lifespan. Pre-clinical and clinical data suggest that metformin, via suppression of pro-inflammatory pathways, protection of mitochondria and vascular function, and direct actions on neuronal stem cells, may protect against neurodegenerative diseases. Metformin has also been studied for its anti-bacterial, -viral, -malaria efficacy. Collectively, these data raise the question: Is metformin a drug for all diseases? It remains unclear as to whether all of these putative beneficial effects are secondary to its actions as an anti-hyperglycemic and insulin-sensitizing drug, or result from other cellular actions, including inhibition of mTOR (mammalian target for rapamycin), or direct anti-viral actions. Clarification is also sought as to whether data from ex vivo studies based on the use of high concentrations of metformin can be translated into clinical benefits, or whether they reflect a 'Paracelsus' effect. The environmental impact of metformin, a drug with no known metabolites, is another emerging issue that has been linked to endocrine disruption in fish, and extensive use in T2D has also raised concerns over effects on human reproduction. The objectives for this review are to: 1) evaluate the putative mechanism(s) of action of metformin; 2) analyze the controversial evidence for metformin's effectiveness in the treatment of diseases other than type 2 diabetes; 3) assess the reproducibility of the data, and finally 4) reach an informed conclusion as to whether metformin is a drug for all diseases and reasons. We conclude that the primary clinical benefits of metformin result from its insulin-sensitizing and antihyperglycaemic effects that secondarily contribute to a reduced risk of a number of diseases and thereby enhancing healthspan. However, benefits like improving vascular endothelial function that are independent of effects on glucose homeostasis add to metformin's therapeutic actions.

Associations of Dynapenic Obesity and Sarcopenic Obesity with the Risk of Complications in COVID-19

Ageing is associated with changes in body composition, such as low muscle mass (sarcopenia), decreased grip strength or physical function (dynapenia), and accumulation of fat mass. When the accumulation of fat mass synergistically accompanies low muscle mass or reduced grip strength, it results in sarcopenic obesity and dynapenic obesity, respectively. These types of obesity contribute to the increased risk of cardiovascular disease and mortality in the elderly, which could increase the damage caused by COVID-19. In this review, we associated factors that could generate a higher risk of COVID-19 complications in dynapenic obesity and sarcopenic obesity. For example, skeletal muscle regulates the expression of inflammatory cytokines and supports metabolic stress in pulmonary disease; hence, the presence of dynapenic obesity or sarcopenic obesity could be related to a poor prognosis in COVID-19 patients.

Effects of Sustained Hyperglycemia on Skeletal Muscle Lipids in Healthy Subjects

CONTEXT

Sustained increases in plasma glucose promote skeletal muscle insulin resistance independent from obesity and dyslipidemia (ie, glucotoxicity). Skeletal muscle lipids are key molecular determinants of insulin action, yet their involvement in the development of glucotoxicity is unclear.

OBJECTIVE

To explore the impact of mild physiologic hyperglycemia on skeletal muscle lipids.

DESIGN

Single group pretest-posttest.

PARTICIPANTS

Healthy males and females with normal glucose tolerance.

INTERVENTIONS

72-hour glucose infusion raising plasma glucose by ~50 mg/dL.

MAIN OUTCOME MEASURES

Skeletal muscle lipids, insulin sensitivity, lipid oxidation.

RESULTS

Despite impairing insulin-mediated glucose disposal and suppressing fasting lipid oxidation, hyperglycemia did not alter either the content or composition of skeletal muscle triglycerides, diacylglycerides, or phospholipids. Skeletal muscle ceramides decreased after glucose infusion, likely in response to a reduction in free fatty acid concentrations.

CONCLUSIONS

Our results demonstrate that the major lipid pools in skeletal muscle are unperturbed by sustained increases in glucose availability and suggest that glucotoxicity and lipotoxicity drive insulin resistance through distinct mechanistic pathways.

Gellan Gum Is a Suitable Biomaterial for Manual and Bioprinted Setup of Long-Term Stable, Functional 3D-Adipose Tissue Models

Due to its wide-ranging endocrine functions, adipose tissue influences the whole body’s metabolism. Engineering long-term stable and functional human adipose tissue is still challenging due to the limited availability of suitable biomaterials and adequate cell maturation. We used gellan gum (GG) to create manual and bioprinted adipose tissue models because of its similarities to the native extracellular matrix and its easily tunable properties. Gellan gum itself was neither toxic nor monocyte activating. The resulting hydrogels exhibited suitable viscoelastic properties for soft tissues and were stable for 98 days in vitro. Encapsulated human primary adipose-derived stem cells (ASCs) were adipogenically differentiated for 14 days and matured for an additional 84 days. Live-dead staining showed that encapsulated cells stayed viable until day 98, while intracellular lipid staining showed an increase over time and a differentiation rate of 76% between days 28 and 56. After 4 weeks of culture, adipocytes had a univacuolar morphology, expressed perilipin A, and secreted up to 73% more leptin. After bioprinting establishment, we demonstrated that the cells in printed hydrogels had high cell viability and exhibited an adipogenic phenotype and function. In summary, GG-based adipose tissue models show long-term stability and allow ASCs maturation into functional, univacuolar adipocytes.

The Impact of Metabolic Syndrome and Obesity on the Evolution of Diastolic Dysfunction in Apparently Healthy Patients Suffering from Post-COVID-19 Syndrome

(1) Background: Coronavirus disease 2019 (COVID-19) has a worse prognosis in individuals with obesity and metabolic syndrome (MS), who often develop cardiovascular complications that last throughout recovery. (2) Methods: This study aimed to analyze the evolution of diastolic dysfunction (DD), assessed by transthoracic echocardiography (TTE), in 203 individuals with and without obesity and/or MS diagnosed with post-COVID-19 syndrome. (3) Results: DD was frequently diagnosed in patients with MS and obesity, but also in those without obesity (62.71% and 56.6%, respectively), in comparison to 21.97% of subjects without MS (p ˂ 0.001). Almost half of the patients with obesity and MS had more severe DD (types 2 and 3). As for evolution, the prevalence and severity of DD, particularly types 1 and 2, decreased gradually, in parallel with the improvement of symptoms, progress being more evident in subjects without MS. DD of type 3 did not show a significant reduction (p = 0.47), suggesting irreversible myocardial damages. Multivariate regression analysis indicated that the number of MS factors, the severity of initial pulmonary injury, and protein C levels could explain DD evolution. (4) Conclusions: DD was commonly diagnosed in individuals with post-COVID-19 syndrome, particularly in those with MS and obesity. After 6 months, DD evolution, excepting that of type 3, showed a significant improvement, mostly in patients without MS.

Obesity and COVID-19: Mechanistic Insights From Adipose Tissue

Obesity is associated with an increase in morbidity and mortality from coronavirus disease 2019 (COVID-19). The risk is related to the cytokine storm, a major contributor to multiorgan failure and a pathological character of COVID-19 patients with obesity. While the exact cause of the cytokine storm remains elusive, disorders in energy metabolism has provided insights into the mechanism. Emerging data suggest that adipose tissue in obesity contributes to the disorders in several ways. First, adipose tissue restricts the pulmonary function by generation of mechanical pressures to promote systemic hypoxia. Second, adipose tissue supplies a base for severe acute respiratory syndrome coronavirus 2 entry by overexpression of viral receptors [angiotensin-converting enzyme 2 and dipeptidyl peptidase 4]. Third, impaired antiviral responses of adipocytes and immune cells result in dysfunction of immunologic surveillance as well as the viral clearance systems. Fourth, chronic inflammation in obesity contributes to the cytokine storm by secreting more proinflammatory cytokines. Fifth, abnormal levels of adipokines increase the risk of a hyperimmune response to the virus in the lungs and other organs to enhance the cytokine storm. Mitochondrial dysfunction in adipocytes, immune cells, and other cell types (endothelial cells and platelets, etc) is a common cellular mechanism for the development of cytokine storm, which leads to the progression of mild COVID-19 to severe cases with multiorgan failure and high mortality. Correction of energy surplus through various approaches is recommended in the prevention and treatment of COVID-19 in the obese patients.

HbA1c measurement may save COVID-19 inpatients from overlooked diabetes

Aims/Introduction

To investigate overlooked diabetes in patients with coronavirus disease 2019 (COVID‐19).

Materials and Methods

In total, 462 COVID‐19 inpatients were included in this retrospective study. The presence of diabetes before COVID‐19 admission, and the HbA1c and blood glucose levels at admission were examined.

Results

Of the 462 patients, 116 had diabetes. Seventy‐six patients had been diagnosed with diabetes before COVID‐19 admission, and 40 patients were diagnosed for the first time. Of the patients with diabetes 72% required insulin. Patients with diabetes were significantly (P < 0.05) older, more likely to be male, heavier, and showed a lower eGFR. Patients with overlooked diabetes showed a lower HbA1c (average 7.1% vs 7.5%), a lower casual blood glucose (average 157 vs 179 mg/dL), and they used less insulin per day during hospitalization (average 16.0 units vs 34.5 units) than patients with previously diagnosed diabetes. Patients with overlooked diabetes tended to have more severe COVID‐19 than those with pre‐diagnosed diabetes. Multivariable logistic regression analyses showed that the increased odds ratios (ORs) of aggravation in all patients with COVID‐19 were associated with age [OR 1.04], BMI [OR 1.05], and diabetes [OR 2.15]. The risk factors for aggravation in patients with COVID‐19 and diabetes were age [OR 1.05] and HbA1c [OR 1.45].

Conclusions

Diabetes is a predictor of COVID‐19 aggravation. Furthermore, in COVID‐19 patients with diabetes, high HbA1c levels are a risk factor for severe COVID‐19. A total of 8.7% of COVID‐19 inpatients were diagnosed with diabetes after HbA1c was measured on admission. Therefore, it is important to measure HbA1c in COVID‐19 patients.

Longitudinal Study of DNA Methylation and Epigenetic Clocks Prior to and Following Test-Confirmed COVID-19 and mRNA Vaccination

The host epigenetic landscape rapidly changes during SARS-CoV-2 infection, and evidence suggest that severe COVID-19 is associated with durable scars to the epigenome. Specifically, aberrant DNA methylation changes in immune cells and alterations to epigenetic clocks in blood relate to severe COVID-19. However, a longitudinal assessment of DNA methylation states and epigenetic clocks in blood from healthy individuals prior to and following test-confirmed non-hospitalized COVID-19 has not been performed. Moreover, the impact of mRNA COVID-19 vaccines upon the host epigenome remains understudied. Here, we first examined DNA methylation states in the blood of 21 participants prior to and following test-confirmed COVID-19 diagnosis at a median time frame of 8.35 weeks; 756 CpGs were identified as differentially methylated following COVID-19 diagnosis in blood at an FDR adjusted p-value < 0.05. These CpGs were enriched in the gene body, and the northern and southern shelf regions of genes involved in metabolic pathways. Integrative analysis revealed overlap among genes identified in transcriptional SARS-CoV-2 infection datasets. Principal component-based epigenetic clock estimates of PhenoAge and GrimAge significantly increased in people over 50 following infection by an average of 2.1 and 0.84 years. In contrast, PCPhenoAge significantly decreased in people fewer than 50 following infection by an average of 2.06 years. This observed divergence in epigenetic clocks following COVID-19 was related to age and immune cell-type compositional changes in CD4+ T cells, B cells, granulocytes, plasmablasts, exhausted T cells, and naïve T cells. Complementary longitudinal epigenetic clock analyses of 36 participants prior to and following Pfizer and Moderna mRNA-based COVID-19 vaccination revealed that vaccination significantly reduced principal component-based Horvath epigenetic clock estimates in people over 50 by an average of 3.91 years for those who received Moderna. This reduction in epigenetic clock estimates was significantly related to chronological age and immune cell-type compositional changes in B cells and plasmablasts pre- and post-vaccination. These findings suggest the potential utility of epigenetic clocks as a biomarker of COVID-19 vaccine responses. Future research will need to unravel the significance and durability of short-term changes in epigenetic age related to COVID-19 exposure and mRNA vaccination.

Cardiometabolic syndrome - an emergent feature of Long COVID?

Among the multi-organ complications of Long COVID, those associated with cardiometabolic syndrome were some of the most prevalent in recent studies of population-scale data. Given the potential health and economic burdens, there is an urgent need to better define the inflammatory processes involved.

A FAsT contribution: Adipocytes rewire their metabolism to acquire immune functions

Adipose tissue has been linked to inflammation and various physiological processes. In this issue of Cell Metabolism, Caputa et al. describe that perinodal adipocytes adapt their metabolism to actively participate in an immune response against intracellular Listeria monocytogenes.

Visceral fat inflammation and fat embolism are associated with lung's lipidic hyaline membranes in subjects with COVID-19

BACKGROUND

Preliminary data suggested that fat embolism could explain the importance of visceral obesity as a critical determinant of coronavirus disease-2019 (COVID-19).

METHODS

We performed a comprehensive histomorphologic analysis of autoptic visceral adipose tissue (VAT), lungs and livers of 19 subjects with COVID-19 (COVID-19+), and 23 people without COVID-19 (controls). Human adipocytes (hMADS) infected with SARS-CoV-2 were also studied.

RESULTS

Although there were no between-group differences in body-mass-index and adipocytes size, a higher prevalence of CD68+ macrophages among COVID-19+ VAT was detected (p = 0.005) and accompanied by crown-like structures presence, signs of adipocytes stress and death. Consistently, human adipocytes were successfully infected by SARS-CoV-2 in vitro and displayed lower cell viability. Being VAT inflammation associated with lipids spill-over from dead adipocytes, we studied lipids distribution by ORO. Lipids were observed within lungs and livers interstitial spaces, macrophages, endothelial cells, and vessels lumen, features suggestive of fat embolism syndrome, more prevalent among COVID-19+ (p < 0.001). Notably, signs of fat embolism were more prevalent among people with obesity (p = 0.03) independently of COVID-19 diagnosis, suggesting that such condition may be an obesity complication exacerbated by SARS-CoV-2 infection. Importantly, all infected subjects' lungs presented lipids-rich (ORO+) hyaline membranes, formations associated with COVID-19-related pneumonia, present only in one control patient with non-COVID-19-related pneumonia. Importantly, transition aspects between embolic fat and hyaline membranes were also observed.

CONCLUSIONS

This study confirms the lung fat embolism in COVID-19+ patients and describes for the first time novel COVID-19-related features possibly underlying the unfavorable prognosis in people with COVID-19 and obesity.

Diabetes Fact Sheet in Korea 2021

BACKGROUND

This study aimed to investigate the prevalence and management of diabetes mellitus, risk-factor control, and comorbidities among Korean adults.

METHODS

We conducted a cross-sectional analysis of data from the Korea National Health and Nutrition Examination Survey to assess the prevalence, treatment, risk factors, comorbidities, and self-management behaviors of diabetes mellitus from 2019 to 2020. We also analyzed data from the Korean National Health Insurance Service to evaluate the use of antidiabetic medications in people with diabetes mellitus from 2002 through 2018.

RESULTS

Among Korean adults aged 30 years or older, the estimated prevalence of diabetes mellitus was 16.7% in 2020. From 2019 through 2020, 65.8% of adults with diabetes mellitus were aware of the disease and treated with antidiabetic medications. The percentage of adults with diabetes mellitus who achieved glycosylated hemoglobin (HbA1c) <6.5% was 24.5% despite the increased use of new antidiabetic medications. We found that adults with diabetes mellitus who achieved all three goals of HbA1c <6.5%, blood pressure (BP) <140/85 mm Hg, and low-density lipoprotein cholesterol <100 mg/dL were 9.7%. The percentage of self-management behaviors was lower in men than women. Excess energy intake was observed in 16.7% of adults with diabetes mellitus.

CONCLUSION

The prevalence of diabetes mellitus among Korean adults remained high. Only 9.7% of adults with diabetes mellitus achieved all glycemic, BP, and lipid controls from 2019 to 2020. Continuous evaluation of national diabetes statistics and a national effort to increase awareness of diabetes mellitus and improve comprehensive diabetes care are needed.

Glucometabolic changes influence hospitalization and outcome in patients with COVID-19: An observational cohort study

AIMS

The aim was to report the prevalence of diabetes status in patients hospitalized with COVID-19 and assess the association between the glucometabolic status at admission and 90-day mortality.

METHODS

Consecutive patients hospitalized with COVID-19 were included in the study. All participants included had an HbA_1c measurement 60 days prior to or within 7 days after admission. We studied the association between diabetes status, the glycemic gap (difference between admission and habitual status), admission plasma-glucose, and mortality using Cox proportional hazards regression.

RESULTS

Of 674 patients included, 114 (17%) had normal glucose level, 287 (43%) had pre-diabetes, 74 (11%) had new-onset, and 199 (30%) had diagnosed diabetes. No association between diabetes status, plasma-glucose at admission, and mortality was found. Compared to the 2nd quartile (reference) of glycemic-gap, those with the highest glycemic gap had increased mortality (3rd (HR 2.38 [1.29-4.38], p = 0.005) and 4th quartile (HR 2.48 [1.37-4.52], p = 0.002).

CONCLUSION

Abnormal glucose metabolism was highly prevalent among patients hospitalized with COVID-19. Diabetes status per se or admission plasma-glucose was not associated with a poorer outcome. However, a high glycemic gap was associated with increased risk of mortality, suggesting that, irrespective of diabetes status, glycemic stress serves as an important prognostic marker for mortality.

A global view of the interplay between non-alcoholic fatty liver disease and diabetes

Non-alcoholic fatty liver disease (NAFLD) has become an epidemic, much like other non-communicable diseases (NCDs), such as cancer, obesity, diabetes, and cardiovascular disease. The pathophysiology of NAFLD, particularly involving insulin resistance and subclinical inflammation, is not only closely linked to that of those NCDs but also to a severe course of the communicable disease COVID-19. Genetics alone cannot explain the large increase in the prevalence of NAFLD during the past 2 decades and the increase that is projected for the next decades. Impairment of glucose and lipid metabolic pathways, which has been propelled by the worldwide increase in the prevalence of obesity and type 2 diabetes, is most likely behind the increase in people with NAFLD. As the prevalence of NAFLD varies among subgroups of patients with diabetes and prediabetes identified by cluster analyses, stratification of people with diabetes and prediabetes by major pathological mechanistic pathways might improve the diagnosis of NAFLD and prediction of its progression. In this Review, we aim to understand how diabetes can affect the development of hepatic steatosis and its progression to advanced liver damage. First, we emphasise the extent to which NAFLD and diabetes jointly occur worldwide. Second, we address the major mechanisms that are involved in the pathogenesis of NAFLD and type 2 diabetes, and we discuss whether these mechanisms place NAFLD in an important position to better understand the pathogenesis of NCDs and communicable diseases, such as COVID-19. Third, we address whether this knowledge can be used for personalised treatment of NAFLD in the future. Finally, we discuss the current treatment strategies for people with type 2 diabetes and their effectiveness in treating the spectrum of hepatic diseases from simple steatosis to non-alcoholic steatohepatitis and hepatic fibrosis.

Cardiovascular Dysfunction in COVID-19: Association Between Endothelial Cell Injury and Lactate

Coronavirus disease 2019 (COVID-19), an infectious respiratory disease propagated by a new virus known as Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has resulted in global healthcare crises. Emerging evidence from patients with COVID-19 suggests that endothelial cell damage plays a central role in COVID-19 pathogenesis and could be a major contributor to the severity and mortality of COVID-19. Like other infectious diseases, the pathogenesis of COVID-19 is closely associated with metabolic processes. Lactate, a potential biomarker in COVID-19, has recently been shown to mediate endothelial barrier dysfunction. In this review, we provide an overview of cardiovascular injuries and metabolic alterations caused by SARS-CoV-2 infection. We also propose that lactate plays a potential role in COVID-19-driven endothelial cell injury.

Post-acute sequelae of COVID-19: A metabolic perspective

The SARS-CoV-2 pandemic continues to rage around the world. At the same time, despite strong public health measures and high vaccination rates in some countries, a post-COVID-19 syndrome has emerged which lacks a clear definition, prevalence, or etiology. However, fatigue, dyspnea, brain fog, and lack of smell and/or taste are often characteristic of patients with this syndrome. These are evident more than a month after infection, and are labeled as Post-Acute Sequelae of CoV-2 (PASC) or commonly referred to as long-COVID. Metabolic dysfunction (i.e., obesity, insulin resistance, and diabetes mellitus) is a predisposing risk factor for severe acute COVID-19, and there is emerging evidence that this factor plus a chronic inflammatory state may predispose to PASC. In this article, we explore the potential pathogenic metabolic mechanisms that could underly both severe acute COVID-19 and PASC, and then consider how these might be targeted for future therapeutic approaches.

Hospital management of hyperglycemia in the context of COVID-19: evidence-based clinical considerations

The COVID-19 pandemic led to an unprecedented crisis, and early on, it has been shown that diabetes is an important risk factor for complications and mortality in infected patients, as demonstrated by several studies. Moreover, hyperglycemia, regardless of whether patients have diabetes, is associated with poorer outcomes, which suggests that adequate monitoring and treatment of elevated glycemia in the hospital setting can improve patient outcomes. In patients with COVID-19, glycemic control may be impaired as a consequence of the infection itself (aggravating pre-existing diabetes and potentially precipitating new-onset diabetes), inflammation, or corticosteroid use-a well-established therapy to reduce COVID-19 complications, especially in the intensive care unit. This article reviews the link between diabetes and hyperglycemia, and COVID-19, with a brief review of potential mechanisms, along with emerging evidence on the effect of glycemic control on COVID-19 outcomes, especially in hospital settings.

Pathophysiological Response to SARS-CoV-2 Infection Detected by Infrared Spectroscopy Enables Rapid and Robust Saliva Screening for COVID-19

Fourier transform infrared (FTIR) spectroscopy provides a (bio)chemical snapshot of the sample, and was recently used in proof-of-concept cohort studies for COVID-19 saliva screening. However, the biological basis of the proposed technology has not been established. To investigate underlying pathophysiology, we conducted controlled infection experiments on Vero E6 cells in vitro and K18-hACE2 mice in vivo. Potentially infectious culture supernatant or mouse oral lavage samples were treated with ethanol or 75% (v/v) Trizol for attenuated total reflectance (ATR)-FTIR spectroscopy and proteomics, or RT-PCR, respectively. Controlled infection with UV-inactivated SARS-CoV-2 elicited strong biochemical changes in culture supernatant/oral lavage despite a lack of viral replication, determined by RT-PCR or a cell culture infectious dose 50% assay. Nevertheless, SARS-CoV-2 infection induced additional FTIR signals over UV-inactivated SARS-CoV-2 infection in both cell and mouse models, which correspond to aggregated proteins and RNA. Proteomics of mouse oral lavage revealed increased secretion of kallikreins and immune modulatory proteins. Next, we collected saliva from a cohort of human participants (n = 104) and developed a predictive model for COVID-19 using partial least squares discriminant analysis. While high sensitivity of 93.48% was achieved through leave-one-out cross-validation, COVID-19 patients testing negative on follow-up on the day of saliva sampling using RT-PCR was poorly predicted in this model. Importantly, COVID-19 vaccination did not lead to the misclassification of COVID-19 negatives. Finally, meta-analysis revealed that SARS-CoV-2 induced increases in the amide II band in all arms of this study and in recently published cohort studies, indicative of altered β-sheet structures in secreted proteins. In conclusion, this study reveals a consistent secretory pathophysiological response to SARS-CoV-2, as well as a simple, robust method for COVID-19 saliva screening using ATR-FTIR.

SARS-CoV-2 adipose tissue infection and hyperglycemia: A further step towards the understanding of severe COVID-19

Numerous studies have highlighted the prognostic significance of hyperglycemia in the outcomes of SARS-CoV-2 infection. A number of mechanisms have been proposed as potential drivers of this association, which were, however, up until recently based rather on speculation than on investigational evidence. It has been recently come to light that the development of insulin resistance in the frame of COVID-19 is likely the driving force behind the development of overt hyperglycemia. This results through the infectious insult of the adipose tissue, and is observed in conjunction with aberrant adipokine secretion by host adipocytes, such as decreased adiponectin, as well as a switch towards an antiviral immune secretory profile. These data could have a considerable relevance not only for the management of hyperglycemia in the course of the infection but also for the overall understanding of the pathogenesis of severe COVID-19.

COVID-19 in Joint Ageing and Osteoarthritis: Current Status and Perspectives

COVID-19 is a trending topic worldwide due to its immense impact on society. Recent trends have shifted from acute effects towards the long-term morbidity of COVID-19. In this review, we hypothesize that SARS-CoV-2 contributes to age-related perturbations in endothelial and adipose tissue, which are known to characterize the early aging process. This would explain the long-lasting symptoms of SARS-CoV-2 as the result of an accelerated aging process. Connective tissues such as adipose tissue and musculoskeletal tissue are the primary sites of aging. Therefore, current literature was analyzed focusing on the musculoskeletal symptoms in COVID-19 patients. Hypovitaminosis D, increased fragility, and calcium deficiency point towards bone aging, while joint and muscle pain are typical for joint and muscle aging, respectively. These characteristics could be classified as early osteoarthritis-like phenotype. Exploration of the impact of SARS-CoV-2 and osteoarthritis on endothelial and adipose tissue, as well as neuronal function, showed similar perturbations. At a molecular level, this could be attributed to the angiotensin-converting enzyme 2 expression, renin-angiotensin system dysfunction, and inflammation. Finally, the influence of the nicotinic cholinergic system is being evaluated as a new treatment strategy. This is combined with the current knowledge of musculoskeletal aging to pave the road towards the treatment of long-term COVID-19.

Replication of SARS-CoV-2 in adipose tissue determines organ and systemic lipid metabolism in hamsters and humans

Zickler et al. describe SARS-CoV-2 RNA in post-mortem samples of human adipose tissue. In the hamster model, SARS-CoV-2 propagation in adipose tissue leads to specific changes in lipid metabolism, which are reflected in lipidome patterns of hamster and human plasma.

OUP accepted manuscript

Isolated reports of new-onset diabetes in patients with COVID-19 have led researchers to hypothesise that SARS-CoV-2 infects the human exocrine and endocrine pancreatic cells ex vivo and in vivo. However, existing research lacks experimental evidence indicating that SARS-CoV-2 can infect pancreatic tissue. Here, we found that cats infected with a high dose of SARS-CoV-2 exhibited hyperglycaemia. We also detected SARS-CoV-2 RNA in the pancreatic tissues of these cats, and immunohistochemical staining revealed the presence of SARS-CoV-2 nucleocapsid protein (NP) in the islet cells. SARS-CoV-2 NP and Spike proteins were primarily detected in Glu+ cells, and most Glu+ cells expressed ACE2. Additionally, immune protection experiments conducted on cats showed that the blood glucose levels of immunised cats did not increase post-challenge. Our data indicate the cat pancreas as a SARS-CoV-2 target and suggest that the infection of Glu+ cells could contribute to the metabolic dysregulation observed in SARS-CoV-2-infected cats.

Newly Diagnosed Diabetes Mellitus During COVID-19: The New Pandemic - A Literature Review

Purpose of Review

Coronavirus disease 2019 (COVID-19) has caused a spike in newly diagnosed diabetes mellitus (NDDM). NDDM and COVID-19 infection are not well established as a cause-and-effect relationship; hence, the present review aims to define the underlying causes and consequences of COVID-19 infection in relation to the condition.

Recent Findings

β-Cells are infiltrated by SARS-CoV-2, causing glycometabolic dysfunction and insulin dysregulation. The disease causes systemic inflammation and pro-inflammatory cytokines, as well as hormonal changes that lead to insulin resistance and hyperglycemia that are difficult to manage. As a result of NDDM, complications related to COVID-19 infection become more severe.

Summary

NDDM related to COVID-19 infection complicates hospitalization outcomes and adversely affects quality of life in patients. There are many possible causes and consequences associated with NDDM, but for establishing preventive measures and treatments for NDDM, more evidence regarding its epidemiology, physiopathology, etiology, and nutritional aspects is required.

Discriminatory Value of Adiponectin to Leptin Ratio for COVID-19 Pneumonia

PURPOSE

Obesity is a risk factor for severe coronavirus disease 2019 (COVID-19). Circulating adipokines have been associated with inflammatory burden and amplified or dysregulated immune responses. This study aimed to evaluate the discriminatory ability of adipokines to identify COVID-19 pneumonia and to assess disease severity.

METHODS

We conducted an observational case-control study, with a prospective design, and recruited patients with diagnosis of COVID-19 pneumonia (n = 48) and healthy controls (n = 36), who were matched by age, sex, and BMI. Leptin, adiponectin, IL-6, and TNF-α were measured by ELISA.

RESULTS

Patients with COVID-19 pneumonia had higher levels of leptin, lower adiponectin/leptin (Adpn/Lep) ratio, and higher expression of IL-6. Leptin had an acceptable discriminatory accuracy for COVID-19 pneumonia in patients with BMI >30 (AUC 0.74 [0.58, 0.90]) with a cutoff of 7852 pg/mL and it was associated with maximum respiratory support. By contrast, Adpn/Lep had an excellent discriminatory accuracy for COVID-19 pneumonia in patients with BMI <25 (AUC 0.9 [0.74, 1.06]) with a cutoff of 2.23.

CONCLUSION

Our data indicate that high Adpn/Lep (>2.23) in lean patients is consistent with a state of good health, which decreases in case of inflammatory states, ranging from adipose tissue dysfunction with low-grade inflammation to COVID-19 pneumonia.

Clinical/biochemical characteristics and related outcomes in people with new‐onset diabetes and COVID‐19: experience from a single centre

Aims: It is known that there is a bidirectional relationship between diabetes mellitus (DM) and coronavirus disease (COVID‐19). It has been described that those patients infected with SARS‐CoV‐2 could develop severe metabolic decompensation of pre‐existing or new‐onset DM, although diabetogenic effect of SARS‐CoV‐2 has still not been well consolidated. In fact, the coexistence of SARS‐CoV‐2 infection and new‐onset DM is an infrequent situation.

Methods: We describe the clinical and analytical characteristics of 19 patients admitted to a Spanish tertiary hospital – all 19 having COVID‐19 infection and new‐onset DM.

Results: 12/19 patients (63.2%) were female; the mean age at diagnosis of DM was 54 (39–65) years. The most frequent ethnic group was Caucasian (n=9), followed by Latin‐American (n=7); 7/19 (36.8%) previously met criteria for prediabetes due to altered basal glycaemia or HbA_1c. The mean BMI at diagnosis was 32.26kg/m² (27.62–35.18kg/m²). Eighteen of 19 patients (94.7%) showed bilateral bronchopneumonia. The mean blood glucose of the first blood was 17.5mmol/L (11.1–21.1mmol/L), and the mean HbA_1c was 88mmol/mol (60–115mmol/mol). C‐peptide was requested in eight patients and it was within normal range in 87.5% (n=7) and below the inferior threshold in one case. Autoantibodies were requested in 26.3% (five patients), being negative in 4/5 (80%) and positive in 1/5 (20%). Regarding the type of diabetes diagnosed, 18 were type 2 DM and only one case was diagnosed with type 1 DM. Seventeen had simple hyperglycaemia and two suffered a diabetic ketoacidosis. The mean HbA_1c at 8.0 months (5.0–12.0 months) follow‐up was 42mmol/mol (40–49mmol/mol).

Conclusion: The majority of those described had type 2 DM that appears to have been unmasked by the COVID‐19 infection, since they had high HbA_1c and several risk factors for diabetes development, such as obesity and prediabetes. Most of them had their pancreatic reserve preserved, and this may suggest insulin resistance as the aetiology rather than direct beta‐cell damage. A good evolution of diabetes after hospital discharge was observed in the patients followed up at our centre. Copyright © 2022 John Wiley & Sons.

Causal associations between body fat accumulation and COVID-19 severity: A Mendelian randomization study

Previous studies reported associations between obesity measured by body mass index (BMI) and coronavirus disease 2019 (COVID-19). However, BMI is calculated only with height and weight and cannot distinguish between body fat mass and fat-free mass. Thus, it is not clear if one or both of these measures are mediating the relationship between obesity and COVID-19. Here, we used Mendelian randomization (MR) to compare the independent causal relationships of body fat mass and fat-free mass with COVID-19 severity. We identified single nucleotide polymorphisms associated with body fat mass and fat-free mass in 454,137 and 454,850 individuals of European ancestry from the UK Biobank, respectively. We then performed two-sample MR to ascertain their effects on severe COVID-19 (cases: 4,792; controls: 1,054,664) from the COVID-19 Host Genetics Initiative. We found that an increase in body fat mass by one standard deviation was associated with severe COVID-19 (odds ratio (OR)_{body fat mass} = 1.61, 95% confidence interval [CI]: 1.28-2.04, P = 5.51 × 10^-5; OR_{body fat-free mass} = 1.31, 95% CI: 0.99-1.74, P = 5.77 × 10^-2). Considering that body fat mass and fat-free mass were genetically correlated with each other (r = 0.64), we further evaluated independent causal effects of body fat mass and fat-free mass using multivariable MR and revealed that only body fat mass was independently associated with severe COVID-19 (OR_{body fat mass} = 2.91, 95% CI: 1.71-4.96, P = 8.85 × 10^-5 and OR_{body fat-free mass} = 1.02, 95%CI: 0.61-1.67, P = 0.945). In summary, this study demonstrates the causal effects of body fat accumulation on COVID-19 severity and indicates that the biological pathways influencing the relationship between COVID-19 and obesity are likely mediated through body fat mass.

COVID-19 induces new-onset insulin resistance and lipid metabolic dysregulation via regulation of secreted metabolic factors

Abnormal glucose and lipid metabolism in COVID-19 patients were recently reported with unclear mechanism. In this study, we retrospectively investigated a cohort of COVID-19 patients without pre-existing metabolic-related diseases, and found new-onset insulin resistance, hyperglycemia, and decreased HDL-C in these patients. Mechanistically, SARS-CoV-2 infection increased the expression of RE1-silencing transcription factor (REST), which modulated the expression of secreted metabolic factors including myeloperoxidase, apelin, and myostatin at the transcriptional level, resulting in the perturbation of glucose and lipid metabolism. Furthermore, several lipids, including (±)5-HETE, (±)12-HETE, propionic acid, and isobutyric acid were identified as the potential biomarkers of COVID-19-induced metabolic dysregulation, especially in insulin resistance. Taken together, our study revealed insulin resistance as the direct cause of hyperglycemia upon COVID-19, and further illustrated the underlying mechanisms, providing potential therapeutic targets for COVID-19-induced metabolic complications.

SARS-CoV-2 and EBV; the cost of a second mitochondrial "whammy"?

We, and others, have suggested that as the SARS-CoV-2 virus may modulate mitochondrial function, good mitochondrial reserve and health could be key in determining disease severity when exposed to this virus, as the immune system itself is dependent on this organelle's function. With the recent publication of a paper showing that long COVID could be associated with the reactivation of the Epstein Barr Virus, which is well known to manipulate mitochondria, we suggest that this could represent a second mitochondrial "whammy" that might support the mitochondrial hypothesis underlying COVID-19 severity and potentially, the occurrence of longer-term symptoms. As mitochondrial function declines with age, this could be an important factor in why older populations are more susceptible. Key factors which ensure optimal mitochondrial health are generally those that ensure healthy ageing, such as a good lifestyle with plenty of physical activity. The ability of viruses to manipulate mitochondrial function is well described, and it is now also thought that for evolutionary reasons, they also manipulate the ageing process. Given that slowing the ageing process could well be linked to better economic outcomes, the link between mitochondrial health, economics, COVID-19 and other viruses, as well as lifestyle, needs to be considered.