Editorial: Obesity, metabolic phenotypes and COVID-19

Assessment of immune function in individuals without and with obesity and normoglycemia, glucose intolerance, or type 2 diabetes: primary findings of the NutrIMM study, a single-arm controlled feeding trial

BACKGROUND

Obesity and type 2 diabetes (T2D) are associated with immune dysfunction, increasing infection susceptibility and impairing immune responses. However, the independent effects of obesity and hyperglycemia on immune dysregulation remain unclear, particularly under controlled dietary conditions.

OBJECTIVES

The Nutrition and Immunity study investigated the effects of obesity and hyperglycemia on immune cell function, phenotype, and systemic inflammation in individuals with obesity with or without T2D, compared with lean individuals with normoglycemia.

METHODS

This single-arm controlled feeding trial included 112 participants across 4 groups: lean-normoglycemic (Lean-NG), obese-normoglycemic (OB-NG), obese-glucose intolerant (OB-GI), and obese-T2D. Participants followed a standardized isocaloric North American diet for 4 wk. Blood samples were collected at baseline and week 4. One-way and repeated measures analysis of variance assessed group differences and/or dietary effects. Linear regression analyses examined associations between glucose control and immune function.

RESULTS

C-reactive protein levels were higher in the OB-NG group [mean difference (MD): 4.1 mg/L; 95% confidence interval (CI): 1.7, 6.6], OB-GI group (MD: 3.1 mg/L; 95% CI: 0.82, 5.4), and OB-T2D (MD: 2.7 mg/L; 95% CI: 0.3, 5.1) compared with Lean-NG, whereas interleukin (IL)-2 secretion was lower in OB-T2D group (MD: -2086.4 pg/mL; 95% CI: -4375.9, -37.4). OB-T2D also exhibited higher neutrophils (MD: 0.7%; 95% CI: 0.01, 0.12), Systemic Immune-Inflammation Index (MD: 155.3; 95% CI: 0.90, 309.7), and system inflammation response index (MD: 0.58, 95% CI: 0.20, 0.97) compared with Lean-NG, and a lower proportion of naïve CD8+ T cells than OB-NG (MD: -13.7%; 95% CI: -27.3, -0.14). Regression analysis showed an association between hyperglycemia and reduced immune function, particularly for IL-2 (β = -0.296, P = 0.037) and interferon-gamma secretion (β = -0.325, P = 0.017).

CONCLUSIONS

Immune function is compromised in obesity and worsens in T2D, suggesting both obesity and poor glucose control drive immune dysfunction. Addressing metabolic health may help mitigate immune dysfunction and inflammation in obesity-related conditions.

TRIAL REGISTRATION NUMBER

This trial was registered at clinicaltrials.gov as NCT04291391 (https://www.

CLINICALTRIALS

gov/study/NCT04291391?term=NCT04291391&rank=1).

Metabolic health is more strongly associated with the severity and mortality of coronavirus disease 2019 than obesity

BACKGROUND

Obesity has been suggested to be associated with the coronavirus disease 2019 (COVID-19); however, it is unclear whether obesity or metabolic abnormalities accompanied by obesity have a stronger association with COVID-19 risk.

METHODS

This study used the Korea Disease Control and Prevention Agency database, which includes information about the COVID-19 diagnosis and mortality dates of the entire Korean population between October 2020 and December 2021 (for diagnosis) or March 2022 (for mortality). A total of 24,310,283 adults were included and classified into four metabolic obesity phenotypes: (1) metabolically healthy and normal weight (MHNW), (2) metabolically unhealthy and normal weight (MUNW), (3) metabolically healthy and obese (MHO), and (4) metabolically unhealthy and obese (MUO). COVID-19 mortality and severity were compared according to metabolic obesity phenotypes in the total population and in each age group (20-<50 years, 50-<70 years, and ≥ 70 years). Additionally, major adverse cardiovascular events (MACE) after COVID-19 infection were compared according to metabolic obesity phenotypes.

RESULTS

A total of 3, 956, 807 participants (16.3%) were diagnosed with COVID-19 during the study period. Among them, metabolically unhealthy subjects had higher mortality rates than metabolically healthy subjects (0.81% for MUNW, 0.40% for MUO, 0.23% for MHNW, and 0.19% for MHO). The rates of severe hospitalized disease were also higher in metabolically unhealthy subjects than in healthy subjects (0.59% for MUNW, 0.55% for MUO, 0.19% for MHNW, and 0.31% for MHO). In the subgroup analyses by age, similar trends were observed in subjects aged 20-50 and 50-70 years, respectively. Additionally, the incidence of total MACE was increased in metabolically unhealthy individuals.

CONCLUSIONS

The study shows that metabolic health is more strongly associated with COVID-19 mortality and severity than obesity, particularly in adults aged < 70 years.

Mortality risk in patients with obesity and COVID-19 infection: a systematic review and meta-analysis

Obesity is a risk factor for severe respiratory diseases, including COVID-19 infection. Meta-analyses on mortality risk were inconsistent. We systematically searched 3 databases (Medline, Embase, CINAHL) and assessed the quality of studies using the Newcastle-Ottawa tool (CRD42020220140). We included 199 studies from US and Europe, with a mean age of participants 41.8-78.2 years, and a variable prevalence of metabolic co-morbidities of 20-80 %. Exceptionally, one third of the studies had a low prevalence of obesity of <20 %. Compared to patients with normal weight, those with obesity had a 34 % relative increase in the odds of mortality (p-value 0.002), with a dose-dependent relationship. Subgroup analyses showed an interaction with the country income. There was a high heterogeneity in the results, explained by clinical and methodologic variability across studies. We identified one trial only comparing mortality rate in vaccinated compared to unvaccinated patients with obesity; there was a trend for a lower mortality in the former group. Mortality risk in COVID-19 infection increases in parallel to an increase in BMI. BMI should be included in the predictive models and stratification scores used when considering mortality as an outcome in patients with COVID-19 infections. Furthermore, patients with obesity might need to be prioritized for COVID-19 vaccination.

Steatotic Liver Disease: Pathophysiology and Emerging Pharmacotherapies

Steatotic liver disease (SLD) displays a dynamic and complex disease phenotype. Consequently, the metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) therapeutic pipeline is expanding rapidly and in multiple directions. In parallel, noninvasive tools for diagnosing and monitoring responses to therapeutic interventions are being studied, and clinically feasible findings are being explored as primary outcomes in interventional trials. The realization that distinct subgroups exist under the umbrella of SLD should guide more precise and personalized treatment recommendations and facilitate advancements in pharmacotherapeutics. This review summarizes recent updates of pathophysiology-based nomenclature and outlines both effective pharmacotherapeutics and those in the pipeline for MASLD/MASH, detailing their mode of action and the current status of phase 2 and 3 clinical trials. Of the extensive arsenal of pharmacotherapeutics in the MASLD/MASH pipeline, several have been rejected, whereas other, mainly monotherapy options, have shown only marginal benefits and are now being tested as part of combination therapies, yet others are still in development as monotherapies. Although the Food and Drug Administration (FDA) has recently approved resmetirom, additional therapeutic approaches in development will ideally target MASH and fibrosis while improving cardiometabolic risk factors. Due to the urgent need for the development of novel therapeutic strategies and the potential availability of safety and tolerability data, repurposing existing and approved drugs is an appealing option. Finally, it is essential to highlight that SLD and, by extension, MASLD should be recognized and approached as a systemic disease affecting multiple organs, with the vigorous implementation of interdisciplinary and coordinated action plans. SIGNIFICANCE STATEMENT: Steatotic liver disease (SLD), including metabolic dysfunction-associated steatotic liver disease and metabolic dysfunction-associated steatohepatitis, is the most prevalent chronic liver condition, affecting more than one-fourth of the global population. This review aims to provide the most recent information regarding SLD pathophysiology, diagnosis, and management according to the latest advancements in the guidelines and clinical trials. Collectively, it is hoped that the information provided furthers the understanding of the current state of SLD with direct clinical implications and stimulates research initiatives.

Epicardial adipose tissue measured from analysis of adipose tissue area using chest CT imaging is the best potential predictor of COVID-19 severity

BACKGROUND

Computed tomography (CT) imaging is widely used for diagnosing and determining the severity of coronavirus disease 2019 (COVID-19). Chest CT imaging can be used to calculate the epicardial adipose tissue (EAT) and upper abdominal visceral adipose tissue (Abd-VAT) areas. The EAT is the main source of inflammatory cytokines involved in chest inflammatory diseases; thus, the EAT area might be a more useful severity predictor than the Abd-VAT area for COVID-19. However, to the best of our knowledge, there are no large-scale reports that sufficiently consider this issue. In addition, there are no reports on the characteristics of patients with normal body mass index (BMI) and high adipose tissue.

AIM

The purpose of this study was to analyze whether the EAT area, among various adipose tissues, was the most associated factor with COVID-19 severity. Using a multicenter COVID-19 patient database, we analyzed the associations of chest subcutaneous, chest visceral, abdominal subcutaneous, and Abd-VAT areas with COVID-19 outcomes. In addition, the clinical significance of central obesity, commonly disregarded by BMI, was examined.

METHODS

This retrospective cohort study evaluated patients with COVID-19 aged ≥18 years In Japan. Data including from chest CT images collected between February 2020 and October 2022 in four hospitals of the Japan COVID-19 Task Force were analyzed. Patient characteristics and COVID-19 severity were compared according to the adipose tissue areas (chest and abdominal subcutaneous adipose tissue [Chest-SAT and Abd-SAT], EAT, and Abd-VAT) calculated from chest CT images.

RESULTS

We included 1077 patients in the analysis. Patients with risk factors of severe COVID-19 such as old age, male sex, and comorbidities had significantly higher areas of EAT and Abd-VAT. High EAT area but not high Abd-VAT area was significantly associated with COVID-19 severity (adjusted odds ratio (aOR): 2.66, 95 % confidence interval [CI]: 1.19-5.93). There was no strong correlation between BMI and VAT. Patients with high VAT area accounted for 40.7 % of the non-obesity population (BMI < 25 kg/m2). High EAT area was also significantly associated with COVID-19 severity in the non-obesity population (aOR: 2.50, 95 % CI: 1.17-5.34).

CONCLUSIONS

Our study indicated that VAT is significantly associated with COVID-19 severity and that EAT is the best potential predictor for risk stratification in COVID-19 among adipose tissue areas. Body composition assessment using EAT is an appropriate marker for identifying obesity patients overlooked by BMI. Considering the next pandemic of the global health crisis, our findings open new avenues for implementing appropriate body composition assessments based on CT imaging.

The Effects of Diabetes and Being Overweight on Patients with Post-COVID-19 Syndrome

In the aftermath of the COVID-19 pandemic, post-COVID-19 syndrome (PCS) remains a challenge and may continue to pose a major health problem in the future. Moreover, the influences of type 2 diabetes and being overweight on PCS remain unclear. This study aimed to assess these influences. We performed an observational study from October 2020 to July 2022, which included 466 patients (269 males and 197 females) with a median age of 65. They were hospitalized due to COVID-19 pneumonia and had persistent symptoms after 1 month of COVID-19 infection. The patients were divided into four groups according to the study objectives: patients with type 2 diabetes, overweight patients, overweight patients with type 2 diabetes, and average-weight patients without type 2 diabetes. The clinical and demographic data collected during hospitalization and regular visits to the Community Healthcare Center dr. Adolf Drolc Maribor were analyzed. Our results showed that type 2 diabetes patients had more difficult courses of treatment and longer hospitalizations. Moreover, more type 2 diabetes patients underwent rehabilitation than the other study groups. The prevailing symptoms of our patients with PCS were dyspnea and fatigue, mostly among female patients with type 2 diabetes. Our study also showed that more women with type 2 diabetes and overweight women with type 2 diabetes suffered from secondary infections. Furthermore, more overweight patients were treated in the intensive care unit than patients from the other groups. However, our study showed an interesting result: patients with type 2 diabetes had the shortest PCS durations. Type 2 diabetes and being overweight are risk factors for PCS onset and prolonged duration. Therefore, our data that revealed a shorter duration of PCS in type 2 diabetes patients than the other investigated groups was unexpected. We believe that answering the questions arising from our unexpected results will improve PCS treatment in general.

BNT162b2 Booster Dose Elicits a Robust Antibody Response in Subjects with Abdominal Obesity and Previous SARS-CoV-2 Infection

Little is known about the long-term durability of the induced immune response in subjects with obesity, particularly in those with an abdominal distribution of adipose tissue. We evaluated SARS-CoV-2-specific antibody responses after BNT162b2 vaccine booster dose, comparing individuals with and without abdominal obesity (AO), discerning between individuals previously infected or not. IgG-TrimericS were measured in 511 subjects at baseline, on the 21st day after vaccine dose 1, and at 1, 3, 6, and 9 months from dose 2, and at 1 and 3 months following the booster dose. To detect SARS-CoV-2 infection, nucleocapsid antibodies were measured at baseline and at the end of the study. Multivariable linear regression evaluated the three-month difference in the absolute variation in IgG-TrimericS levels from booster dose, showing AO and SARS-CoV-2 infection status interactions (p = 0.016). Regardless of possible confounding factors and IgG-TrimericS levels at the booster dose, AO is associated with a higher absolute change in IgG-TrimericS in prior infected individuals (p = 0.0125). In the same regression model, no interaction is highlighted using BMI (p = 0.418). The robust response in the development of antibodies after booster dose, observed in people with AO and previous infection, may support the recommendations to administer a booster dose in this population group.

Dose Intervals and Time since Final Dose on Changes in Metabolic Indices after COVID-19 Vaccination

The rapid development and implementation of COVID-19 vaccines merit understanding its effects on metabolic indices. This retrospective longitudinal study investigated the influence of first-to-second-dose intervals and time since the final dose on the metabolic indices of individuals receiving COVID-19 vaccinations. A total of 318 Saudi subjects (59.7% females) aged 12-60 years received COVID-19 vaccines via the national vaccination program. We collected the anthropometric data and fasting blood samples at specific time points before vaccination and after the final vaccination dose, and biochemical metabolic indices, including glucose and lipid profile, were measured. We also collected the dates of vaccination and COVID-19 history during the study period. The participants were stratified into groups based on first-to-second-dose intervals and time since the final dose to compare pre-and post-vaccination changes in metabolic indices between the groups. Logistic regression analysis revealed no differences in pre- to post-vaccination metabolic status between groups based on first-to-second-dose intervals in either adolescents or adults. However, shorter intervals (≤6 months) between the final dose and follow-up were associated with a decrease in total cardiometabolic components, especially triglyceride levels (OR = 0.39, 95% CI: (0.22-0.68), p < 0.001) than longer intervals (>6 months) in adults. In conclusion, time duration since final dose was associated with pre- to post-vaccination changes in metabolic indices, especially triglyceride levels, indicating that post-vaccination improvements wane over time. Further research is needed to validate the observed relationship, as it may contribute to optimizing vaccine effectiveness and safety in the future.

Milestones in the journey towards addressing obesity; Past trials and triumphs, recent breakthroughs, and an exciting future in the era of emerging effective medical therapies and integration of effective medical therapies with metabolic surgery

The 21st century is characterized by an increasing incidence and prevalence of obesity and the burden of its associated comorbidities, especially cardiometabolic diseases, which are reaching pandemic proportions. In the late '90s, the "black box" of adipose tissue and energy homeostasis was opened with the discovery of leptin, transforming the adipose tissue from an "inert fat-storage organ" to the largest human endocrine organ and creating the basis on which more intensified research efforts to elucidate the pathogenesis of obesity and develop novel treatments were based upon. Even though leptin was eventually not proven to be the "standalone magic bullet" for the treatment of common/polygenic obesity, it has been successful in the treatment of monogenic obesity syndromes. Additionally, it shifted the paradigm of treating obesity from a condition due to "lack of willpower" to a disease due to distinct underlying biological mechanisms for which specific pharmacotherapies would be needed in addition to lifestyle modification. Subsequently, the melanocortin pathway proved to be an equally valuable pathway for the pharmacotherapy of obesity. Melanocortin receptor agonists have recently been approved for treating certain types of syndromic obesity. Other molecules- such as incretins, implicated in energy and glucose homeostasis- are secreted by the gastrointestinal tract. Glucagon-like peptide 1 (GLP-1) is the most prominent one, with GLP-1 analogs approved for common/polygenic obesity. Unimolecular combinations with other incretins, e.g., GLP-1 with gastric inhibitory polypeptide and/or glucagon, are expected to be approved soon as more effective pharmacotherapies for obesity and its comorbidities. Unimolecular combinations with other compounds and small molecules activating the receptors of these molecules are currently under investigation as promising future pharmacotherapies. Moreover, metabolic and bariatric surgery has also demonstrated impressive results, especially in the case of morbid obesity. Consequently, this broadening therapeutic armamentarium calls for a well-thought-after and well-coordinated multidisciplinary approach, for instance, through cardiometabolic expertise centers, that would ideally address effectively and cost-effectively obesity and its comorbidities, providing tangible benefits to large segments of the population.

Folate metabolism negatively regulates OAS-mediated antiviral innate immunity via ADAR3/endogenous dsRNA pathway

BACKGROUND

Folate (FA) is an essential cofactor in the one-carbon (1C) metabolic pathway and participates in amino acid metabolism, purine and thymidylate synthesis, and DNA methylation. FA metabolism has been reported to play an important role in viral replications; however, the roles of FA metabolism in the antiviral innate immune response are unclear.

OBJECTIVE

To evaluate the potential regulatory role of FA metabolism in antiviral innate immune response, we establish the model of FA deficiency (FAD) in vitro and in vivo. The molecular and functional effects of FAD on 2'-5'-oligoadenylate synthetases (OAS)-associated antiviral innate immunity pathways were assessed; and the potential relationship between FA metabolism and the axis of adenosine deaminases acting on RNA 3 (ADAR3)/endogenous double-stranded RNA (dsRNA)/OAS was further explored in the present study, as well as the potential translatability of these findings in vivo.

METHODS

FA-free RPMI 1640 medium and FA-free feed were used to establish the model of FAD in vitro and in vivo. And FA and homocysteine (Hcy) concentrations in cell culture supernatants and serum were used for FAD model evaluation. Ribonucleoprotein immunoprecipitation assay was used to enrich endogenous dsRNA, and dot-blot was further used for quantitative analysis of endogenous dsRNA. Western-blot assay, RNA isolation and quantitative real-time PCR, immunofluorescence assay, and other molecular biology techniques were used for exploring the potential mechanisms.

RESULTS

In this study, we observed that FA metabolism negatively regulated OAS-mediated antiviral innate immune response. Mechanistically, FAD induced ADAR3, which interacted with endogenous dsRNA, to inhibit deaminated adenosine (A) being converted into inosine (I), leading to the cytoplasmic accumulation of dsRNA. Furthermore, endogenous dsRNA accumulated in cytoplasm triggered the host immune activation, thus promoting the expression of OAS2 to suppress the replication of viruses. Additionally, injection of 8-Azaadenosine to experimental animals, an A-to-I editing inhibitor, efficiently enhanced OAS-mediated antiviral innate immune response to reduce the viral burden in vivo.

CONCLUSIONS

Taken together, our present study provided a new perspective to illustrate a relationship between FA metabolism and the axis of ADAR3/endogenous dsRNA/OAS, and a new insight for the treatment of RNA viral infectious diseases by targeting the axis of ADAR3/endogenous dsRNA/OAS.

Four Waves of the COVID-19 Pandemic: Comparison of Clinical and Pregnancy Outcomes

During the last two and a half years, clinical manifestations, disease severity, and pregnancy outcomes have differed among pregnant patients with SARS-CoV-2 infection. These changes were preceded by the presence of new variants of SARS-CoV-2, known in the literature as variants of concern. The aim of this study is to describe the differences between maternal clinical characteristics and perinatal outcomes among pregnant women with COVID-19 during four waves of the COVID-19 epidemic in Serbia. This retrospective study included a series of 192 pregnant patients who were hospitalized due to the severity of their clinical status of SARS-CoV-2 infection. During four outbreaks of COVID-19 infection in Serbia, we compared and analyzed three sets of variables, including signs, symptoms, and characteristics of COVID-19 infection, clinical endpoints, and maternal and newborn parameters. During the dominance of the Delta variant, the duration of hospitalization was the longest (10.67 ± 1.42 days), the frequency of stillbirths was the highest (17.4%), as well as the frequency of progression of COVID infection (28.9%) and the requirement for non-invasive oxygen support (37%). The dominance of the Delta variant was associated with the highest number of prescribed antibiotics (2.35 ± 0.28), the most common presence of nosocomial infections (21.7%), and the highest frequency of corticosteroid therapy use (34.8%). The observed differences during the dominance of four variants of concern are potential pathways for risk stratification and the establishment of timely and proper treatments for pregnant patients. Early identification of the Delta variant, and possibly some new variants with similar features in the future, should be a priority and, perhaps, even an opportunity to introduce more accurate and predictive clinical algorithms for pregnant patients.

Mendelian randomization study of obesity and type 2 diabetes in hospitalized COVID-19 patients

BACKGROUND

Both obesity and type 2 diabetes (T2D) are reported to be highly enriched in hospitalized COVID-19 patients. Due to the close correlation between obesity and T2D, it is important to examine whether obesity and T2D are independently related to COVID-19 hospitalization.

OBJECTIVE

To examine the causal effect of obesity and T2D in hospitalized COVID-19 patients using Mendelian randomization (MR).

RESEARCH DESIGN AND METHODS

This two-sample MR analysis applied genetic markers of obesity identified in the genome wide association study (GWAS) by the GIANT Consortium as instrumental variables (IVs) of obesity; and genetic markers of T2D identified by the DIAGRAM Consortium as IVs of T2D. The MR analysis was performed in hospitalized COVID-19 patient by the COVID-19 Host Genetics Initiative using the MR-Base platform.

RESULTS

All 3 classes of obesity (Class 1/2/3) were shown as the causal risk factors of COVID-19 hospitalization; however, T2D doesn't increase the risk of hospitalization or critically ill COVID-19 as an independent factor.

CONCLUSIONS

Obesity, but not T2D, is a primary risk factor of COVID-19 hospitalization.