Metabolic effects of obesity: A review

Ferredoxin 2 is critical for tumor suppression and lipid homeostasis but dispensable for embryonic development

Ferredoxin 1 and 2 (FDX1/2) constitute an evolutionarily conserved FDX family of iron-sulfur cluster (ISC) containing proteins. FDX1/2 are cognate substrates of ferredoxin reductase (FDXR) and serve as conduits for electron transfer from NADPH to a set of proteins involved in biogenesis of steroids, hemes, ISC and lipoylated proteins. Recently, we showed that Fdx1 is essential for embryonic development and lipid homeostasis. To explore the physiological role of FDX2, we generated Fdx2-deficient mice. Interestingly, we found that unlike Fdx1-null embryos, which were dead at embryonic day 10.5 to 13.5, Fdx2-null mice were viable. We also found that both Fdx2-null and Fdx2-heterozygous mice had a short lifespan and were susceptible to spontaneous tumors and steatohepatitis. Moreover, we found that FDX2-deficiency increased whereas overexpression of FDX2 decreased cytoplasmic accumulation of lipid droplets. Consistently, we found that FDX2 deficiency led to accumulation of cholesterol and triglycerides. Mechanistically, we found that FDX2 deficiency suppressed expression of cholesterol transporter ABCA1 and activated master lipid transcription regulators SREBP1/2, thus leading to altered lipid metabolism. Untargeted lipidomic analysis showed that FDX2 deficiency led to altered biosynthesis of various lipid classes, including cardiolipins, cholesterol, ceramides, triglycerides, and fatty acids. In summary, our findings underscore an indispensable role of FDX2 in tumor suppression and lipid homeostasis at both cellular and organismal levels without being a prerequisite for embryonic development.

Small Molecule Inhibitor of Protein Kinase C DeltaI (PKCδI) Decreases Inflammatory Pathways and Gene Expression and Improves Metabolic Function in Diet-Induced Obese Mouse Model

Obesity promotes metabolic diseases such as type 2 diabetes and cardiovascular disease. PKCδI is a serine/threonine kinase which regulates cell growth, differentiation, and survival. Caspase-3 cleavage of PKCδI releases the C-terminal catalytic fragment (PKCδI_C), which promotes inflammation and apoptosis. We previously demonstrated an increase in PKCδI_C in human obese adipose tissue (AT) and adipocytes. Subsequently, we designed a small molecule drug called NP627 and demonstrated that NP627 specifically inhibited the release of PKCδI_C in vitro. Here, we evaluate the in vivo safety and efficacy of NP627 in a diet-induced obese (DIO) mouse model. The results demonstrate that NP627 treatment in DIO mice increased glucose uptake and inhibited the cleavage of PKCδI_C in the AT as well as in the kidney, spleen, and liver. Next, RNAseq analysis was performed on the AT from the NP627-treated DIO mice. The results show increases in ADIPOQ and CIDEC, upregulation of AMPK, PI3K-AKT, and insulin signaling pathways, while inflammatory pathways were decreased post-NP627 administration. Further, levels of lncRNAs associated with metabolic pathways were affected by NP627 treatment. In conclusion, the study demonstrates that NP627, a small-molecule inhibitor of PKCδI activity, is not toxic and that it improves the metabolic function of DIO mice in vivo.

Obesity's Unexpected Influence: Reduced Alphavirus Transmission and Altered Immune Activation in the Vector

Chikungunya virus (CHIKV) and Mayaro virus (MAYV) are emerging/re-emerging alphaviruses transmitted by Aedes spp. mosquitoes and responsible for recent disease outbreaks in the Americas. The capacity of these viruses to cause epidemics is frequently associated with increased mosquito transmission, which in turn is governed by virus-host-vector interactions. Although many studies have explored virus-vector interactions, significant gaps remain in understanding how vertebrate host factors influence alphavirus transmission by mosquitoes. We previously showed that obesity, a ubiquitous vertebrate host biological factor, reduces alphavirus transmission potential in mosquitoes. We hypothesized that alphavirus-infected obese bloodmeals altered immune genes and/or pathways in mosquitoes, thereby inhibiting virus transmission. To test this, we conducted RNA sequencing (RNA-seq) and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) on midgut RNA from mosquitoes fed on alphavirus-infected lean and obese mice. This approach aimed to identify potential antiviral or proviral genes and pathways altered in mosquitoes after consuming infected obese bloodmeals. We found upregulation of the Toll pathway and downregulation of several metabolic and other genes in mosquitoes fed on alphavirus-infected obese bloodmeals. Through gene knockdown studies, we demonstrated the antiviral role of Toll pathway and proviral roles of AAEL009965 and fatty acid synthase (FASN) in the transmission of alphaviruses by mosquitoes. Therefore, this study utilized obesity to identify factors influencing alphavirus transmission by mosquitoes and this research approach may pave the way for designing broadly effective antiviral measures to combat mosquito-borne viruses, such as releasing transgenic mosquitoes deficient in the identified genes.

Effect of acute anaerobic performance on zinc alpha 2 glycoprotein, apelin and lipasin levels

The aim of this study was to investigate the effects of acute anaerobic exercise on serum levels of adipokines Zinc-α2-glycoprotein (ZAG), apelin, and lipasin. Eighteen male athletes who actively played soccer and trained at least four days a week, with a mean age of 19.11 ± 2.59 years, body weight of 70.61 ± 8.17 kg, height of 176.0 ± 7.71 cm, sport age of 7.22 ± 2.60 years and BMI of 22.76 ± 1.68 kg/m2 participated in the study. Athletes were subjected to the Running-Based Anaerobic Sprint Test (RAST) for anaerobic performance. Blood samples were collected from the athletes 4 times (at rest, 10 minutes, 60 minutes, and 24 hours after exercise). The results of the study showed that acute anaerobic exercise significantly increased ZAG levels (p < 0.05). However, no statistically significant difference was detected in apelin and lipasin levels (p > 0.05). In conclusion, the findings of this study indicate that acute anaerobic exercise is associated with an increase in ZAG levels, but not apelin or lipasin levels. The observations suggest that ZAG may have a specific response to anaerobic exercise, which provides valuable insight into its potential impact on energy metabolism.

Obesity, Inflammation, and Clinical Outcomes in COVID-19: A Multicenter Prospective Cohort Study

CONTEXT

Obesity is a risk factor for coronavirus disease 2019 (COVID-19)-related outcomes; however, the mechanism remains unclear.

OBJECTIVE

The objective of this analysis was to determine whether inflammation mediates the association between obesity and COVID-19 outcomes.

METHODS

The International Study of Inflammation in COVID-19 (ISIC): A Prospective Multi-Center Observational Study Examining the Role of Biomarkers of Inflammation in Predicting Covid-19 Related Outcomes in Hospitalized Patients, was conducted at 10 hospitals in the United States and Europe. Participants were adults hospitalized specifically for COVID-19 between February 1, 2020, through October 19, 2022. Inflammatory biomarkers, including soluble urokinase plasminogen activator receptor (suPAR), were measured at admission. Associations were examined between body mass index (BMI, kg/m2) and a composite of death, need for mechanical ventilation, and renal replacement therapy, stratified by pre- and post-Omicron variants. The contribution of inflammation to the relationship between obesity and outcomes was assessed.

RESULTS

Among 4644 participants (mean age 59.3, 45.6% male, 21.8% BMI ≥ 35), those with BMI > 40 (n = 485) had 55% higher odds of the composite outcome (95% CI, 1.21-1.98) compared with nonobese individuals (BMI < 30, n = 2358) in multivariable analysis. In multiple mediation analysis, only suPAR remained a significant mediator between BMI and composite outcome. Associations were amplified for participants younger than 65 years and with pre-Omicron variants.

CONCLUSION

Obesity is associated with worse outcomes in COVID-19, notably in younger participants and in the pre-Omicron era. Inflammation, as measured by suPAR, is a significant mediator of the association between obesity and COVID-19 outcomes.

Metabolic syndrome in the setting of obesity: impact on in-hospital complications and outcomes after total knee and hip arthroplasty

Aims

This study aims to evaluate the impact of metabolic syndrome in the setting of obesity on in-hospital outcomes and resource use after total joint replacement (TJR).

Methods

A retrospective analysis was conducted using the National Inpatient Sample from 2006 to the third quarter of 2015. Discharges representing patients aged 40 years and older with obesity (BMI > 30 kg/m2) who underwent primary TJR were included. Patients were stratified into two groups with and without metabolic syndrome. The inverse probability of treatment weighting (IPTW) method was used to balance covariates.

Results

The obese cohort with metabolic syndrome was significantly older, more likely to be female, had higher rates of Medicare insurance, and more likely to be non-Hispanic Black than the obese cohort without metabolic syndrome. In the unweighted analysis, patients with obesity and metabolic syndrome were more likely to experience cardiac, gastrointestinal, genitourinary, and postoperative anemia complications, had a longer length of stay, and were less likely to be discharged home compared to obese patients without metabolic syndrome. After adjusting for covariates using IPTW, patients with obesity and metabolic syndrome were more likely to experience postoperative anemia complications only and had lower rates of home discharge, but there were no significant differences in any other complication variables or length of stay.

Conclusion

Given the variability of metabolic health in obesity, the development of tailored perioperative protocols and recommendations acknowledging this variability in metabolic health in obese patients would ultimately potentially benefit patients and improve outcomes of TJR.

Characterization, Anti-glycation, Anti-inflammation, and Lipase Inhibitory Properties of Rauvolfia vomitoria Leaf Extract: In Vitro and In Silico Evaluations for Obesity Treatment

Pancreatic lipase (PLP) is an enzyme responsible for the catalytic hydrolysis of fats and its inhibition is relevant for obesity management. Side effects linked with orthodox inhibitors have, however, paved the way for an increased search for safe natural sources. The present study investigated the anti-glycation, anti-inflammatory, and anti-lipase properties of Rauvolfia vomitoria aqueous (ARV), ethanolic (ERV), and methanolic (MRV) leaf extracts coupled with the molecular interactions of selected bioactive compounds with PLP using in vitro and in silico techniques. Phytochemical constituents were characterized using spectroscopic techniques. Drug-likeness and chemical reactivity profile of selected bioactive compounds were analyzed using SwissADME and quantum chemical calculations. FT-IR and GC-MS affirmed the presence of phenolic compounds including 3-phenyl-2-ethoxypropylphthalimide and 5-methyl-2-phenyl-1H-indole. All extracts showed moderate anti-glycation, anti-inflammatory, and lipase inhibitory capacities relative to standard controls. However, MRV exhibited the highest lipase inhibition (IC50, 0.17 ± 0.01 mg/mL), using a mixed-inhibition pattern. MRV interaction with PLP resulted in decreased secondary structure components of PLP (α-sheet, β-turn). MRV compounds (MCP20, MCP28, etc.) exhibited low chemical hardness, EHOMO-ELUMO energy gap, and high chemical reactivity. Foremost MRV compounds obeyed Lipinski's rule of five for drug-likeness and interacted with PHE-78 amongst others at PLP catalytic domain with high binding affinity (≥ - 9.3 kcal/mol). Pi-alkyl hydrophobic interaction and hydrogen bonding were predominantly involved. Our findings provide scientific insights into the ethnotherapeutic uses of R. vomitoria extracts for the management of obesity and related complications, plus useful information for optimizable drug-like candidates against obesity.