Effects of obesity on IL-33/ST2 system in heart, adipose tissue and liver: study in the experimental model of Zucker rats

Variants in proinflammatory genes IL1RL1, IL1B and IRF4 are associated with overweight in a pediatric Brazilian population

BACKGROUND

Obesity is a chronic complex disease with great prevalence for children all over the world. Characterized for low-grade inflammation associated with several comorbidities such as resistance and type 2 diabetes mellitus (T2DM).

OBJECTIVES

To investigate whether genetic variants in IL10, IL1RL1, IL1B, IRF4, TNF, IL6, and IL33 genes are associated with being overweight in children.

METHODS

We performed the genotyping of 1004 children using Illumina 2.5 Human Omni bead chip, and association analysis on the genetic variants and the overweight through logistic regression adjusted for sex, age and components principal.

RESULTS

Of the seven genes analyzed, 16 SNVs significantly associated. Eleven variants in IL1RL1, two in IL1B and one in IRF4 genes increased overweight risk and two SNVs in IL1RL1 were associated with protection against overweight. The rs2287047-A was negatively associated (OR: 0.66, CI95%: 0.19-0.45) and had a reduced IL1RL1 expression in whole blood (p 0.033) in silico eQTL. The rs12203592-T, in IRF4, was positively associated with being overweight, and led to an increased gene expression in whole blood (p < 0.001) and adipose tissue (p < 0.001).

CONCLUSION

These results suggest that genetic variants in inflammatory genes may play an important role in the development of overweight in children.

Alarmins, COVID-19 and comorbidities

The coronavirus SARS-CoV-2, the aetiological agent of COVID-19 disease, is representing a worldwide threat for the medical community and the society at large so that it is being defined as "the twenty-first-century disease". Often associated with a severe cytokine storm, leading to more severe cases, it is mandatory to block such occurrence early in the disease course, to prevent the patients from having more severe, sometimes fatal, outcomes. In this framework, early detection of "danger signals", possibly represented by alarmins, can represent one of the most promising strategies to effectively tailor the disease and to better understand the underlying mechanisms eventually leading to death or severe consequences. In light of such considerations, the present article aims at evaluating the role of alarmins in patients affected by COVID-19 disease and the relationship of such compounds with the most commonly reported comorbidities. The conducted researches demonstrated yet poor literature on this specific topic, however preliminarily confirming a role for danger signals in the amplification of the inflammatory reaction associated with SARS-CoV-2 infection. As such, a number of chronic conditions, including metabolic syndrome, gastrointestinal and respiratory diseases, in turn, associated with higher levels of alarmins, both foster the infection and predispose to a worse prognosis. According to these preliminary data, prompt detection of high levels of alarmins in patients with COVID-19 and co-morbidities could suggest an immediate intense anti-inflammatory treatment.Key messageAlarmins have a role in the amplification of the inflammatory reaction associated with SARS-CoV-2 infectiona prompt detection of high levels of alarmins in patients with COVID-19 could suggest an immediate intense anti-inflammatory treatment.

Heart failure with preserved left ventricular ejection fraction in patients with obstructive sleep apnea syndrome: prognostic value of biomarkers

Aim      To study the role of soluble ST2 (sST2), N-terminal pro-brain natriuretic peptide (NT-proBNP), and С-reactive protein (CRP) in patients with chronic heart failure and preserved left ventricular ejection fraction (CHF with pLVEF) and syndrome of obstructive sleep apnea (SOSA) in stratification of the risk for development of cardiovascular complications (CVC) during one month of a prospective observation.Material and methods  The study included 71 men with SOSA with an apnea/hypopnea index (AHI) &gt;15 per hour, abdominal obesity, and arterial hypertension. Polysomnographic study and echocardiography according to a standard protocol with additional evaluation of left ventricular myocardial fractional changes and work index were performed for all patients at baseline and after 12 months of observation. Serum concentrations of sST2 , NT-proBNP, and CRP were measured at baseline by enzyme-linked immunoassay (ELISA).Results The ROC analysis showed that the cutoff point characterizing the development of CVC were sST2 concentrations ≥29.67 ng/l (area under the curve, AUC, 0.773, sensitivity 65.71 %, specificity 86.11 %; p&lt;0.0001) while concentrations of NT-proBNP (AUC 0.619; p=0.081) and CRP (AUC 0.511; р=0.869) were not prognostic markers for the risk of CVC. According to data of the ROC analysis, all patients were divided into 2 groups based on the sST2 cutoff point: group 1 included 29 patients with ST2 ≥29.67 ng/l and group 2 included 42 patients with ST2 &lt;29.67 ng/l. The Kaplan-Meyer analysis showed that the incidence of CVC was higher in group 1 than in group 2 (79.3 and 28.6 %, respectively, p&lt;0.001). The regression analysis showed that adding values of AHI and left ventricular myocardial mass index (LVMMI) to sST2 in the model increased the analysis predictive significance.Conclusion      Measuring sST2 concentration may be used as a noninvasive marker for assessment of the risk of CVC development in patients with CHF with pLVEF and SOSA within 12 months of observation. Adding AHI and LVMMI values to the model increases the predictive significance of the analysis.

Effects of IL-33 on 3T3-L1 cells and obese mice models induced by a high-fat diet

Obesity is a syndrome that attributes to many factors such as genetics, diet, lifestyle and environment, which includes an imbalance of immune regulation. IL-33, as a new member of the IL-1 family, is classically associated with type 2 immune responses. Here, IL-33 was investigated for its ability to optimize lipid aggregation and ameliorate the inflammatory response in obesity. In vitro experimental results showed that, compared with the induction group, the treatment with 30 ng/mL IL-33 displayed a reduction in the number of lipid droplets. The expression levels of AceCS1 and PPARγ also decreased in the 30 ng/mL IL-33 group compared to the induction group. For confirmation in vivo, three groups of C57BL/6 mice were treated for 14 weeks: mice in control were fed with a normal diet; mice in the HFD and IL-33 groups were fed with a high-fat diet (HFD) and with sterile PBS or recombinant IL-33, respectively. Liver, muscle, spleen and four types of adipose tissue, as well as serum, were collected for further testing. Our data demonstrated that after 4-week treatment with recombinant IL-33, metabolic parameters in mice were improved significantly (visceral fat weight, glucose and insulin tolerance, liver steatosis, expression of lipid synthesis index and inflammatory response). Moreover, IL-33 treatment regulated the original distribution of IL-33 among different tissues. Hence, IL-33 modulated lipid metabolism and inflammatory response in obesity, which would be a novel therapeutic target for obesity and related metabolic diseases.

Cytokines and the immune response in obesity-related disorders

The increasing prevalence of obesity and the associated morbidity and mortality are important public health problems globally. There is an important relationship between an unhealthy lifestyle and increased serum inflammatory cytokines. Adipocytes secrete several pro-inflammatory cytokines involved in the recruitment and activation of macrophages resulting in chronic low-grade inflammation. Increased cytokines in obese individual are related to the progression of several disorders including cardiovascular disease, hypertension, and insulin resistance. In present review we have summarized the crucial roles of cytokines and their inflammatory functions in obesity-related immune disorders.

Sex-related differences in contemporary biomarkers for heart failure: a review

The use of circulating biomarkers for heart failure (HF) is engrained in contemporary cardiovascular practice and provides objective information about various pathophysiological pathways associated with HF syndrome. However, biomarker profiles differ considerably among women and men. For instance, in the general population, markers of cardiac stretch (natriuretic peptides) and fibrosis (galectin‐3) are higher in women, whereas markers of cardiac injury (cardiac troponins) and inflammation (sST2) are higher in men. Such differences may reflect sex‐specific pathogenic processes associated with HF risk, but may also arise as a result of differences in sex hormone profiles and fat distribution. From a clinical perspective, sex‐related differences in biomarker levels may affect the objectivity of biomarkers in HF management because what is considered to be ‘normal’ in one sex may not be so in the other. The objectives of this review are, therefore: (i) to examine the sex‐specific dynamics of clinically relevant HF biomarkers in the general population, as well as in HF patients; (ii) to discuss the overlap between sex‐related and obesity‐related effects, and (iii) to identify knowledge gaps to stimulate research on sex‐related differences in HF.

Correlative Study on Impaired Prostaglandin E2 Regulation in Epicardial Adipose Tissue and its Role in Maladaptive Cardiac Remodeling via EPAC2 and ST2 Signaling in Overweight Cardiovascular Disease Subjects

There is recent evidence that the dysfunctional responses of a peculiar visceral fat deposit known as epicardial adipose tissue (EAT) can directly promote cardiac enlargement in the case of obesity. Here, we observed a newer molecular pattern associated with LV dysfunction mediated by prostaglandin E2 (PGE₂) deregulation in EAT in a cardiovascular disease (CVD) population. A series of 33 overweight CVD males were enrolled and their EAT thickness, LV mass, and volumes were measured by echocardiography. Blood, plasma, EAT, and SAT biopsies were collected for molecular and proteomic assays. Our data show that PGE₂ biosynthetic enzyme (PTGES-2) correlates with echocardiographic parameters of LV enlargement: LV diameters, LV end diastolic volume, and LV masses. Moreover, PTGES-2 is directly associated with EPAC2 gene (r = 0.70, p < 0.0001), known as a molecular inducer of ST2/IL-33 mediators involved in maladaptive heart remodelling. Furthermore, PGE₂ receptor 3 (PTEGER3) results are downregulated and its expression is inversely associated with ST2/IL-33 expression. Contrarily, PGE₂ receptor 4 (PTGER4) is upregulated in EAT and directly correlates with ST2 molecular expression. Our data suggest that excessive body fatness can shift the EAT transcriptome to a pro-tissue remodelling profile, may be driven by PGE₂ deregulation, with consequent promotion of EPAC2 and ST2 signalling.

Changes in Proteomic Profiles are Related to Changes in BMI and Fat Distribution During 10 Years of Aging

OBJECTIVE

This study investigated how changes in 84 proteins over a 10-year period of aging were related to changes in measures of body fat and distribution over the same period.

METHODS

Cardiovascular candidate proteins were measured using the proximal extension assay technique, along with BMI and waist-hip ratio (WHR), at ages 70, 75, and 80 in 1,016 participants of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) cohort. Associations of changes in plasma protein levels, BMI, and WHR over time were analyzed using linear mixed models.

RESULTS

Changes in 19 and 16 proteins were significantly associated with changes in BMI and WHR, respectively (P < 0.00059), over the investigated 10-year period. Leptin and fatty acid-binding protein 4 were among the proteins most strongly associated with changes in both BMI and WHR. Four of the proteins significantly tracked with change in BMI (P < 0.00059) but not WHR (P > 0.05): endothelial cell-specific molecule 1, pentraxin-related protein PTX3, ST2 protein (also known as interleukin-1 receptor-like 1), and spondin-1. Five proteins tracked with change in WHR (P < 0.00059) but not BMI (P > 0.05): caspase-8, cathepsin L1, oxidized low-density lipoprotein receptor 1, interleukin-6 receptor subunit alpha, and C-C motif chemokine 20.

CONCLUSIONS

This is the first large longitudinal study of how changes in plasma protein signatures are associated with changes in measures of body fat and distribution over 10 years of aging.

Identification of Suitable Reference Genes for Quantitative Gene Expression Analysis in Innervated and Denervated Adipose Tissue from Cafeteria Diet-Fed Rats

Our previous studies show that cafeteria diet increases body adiposity, plasma insulin levels, and sympathetic activity to brown adipose tissue (BAT) and white adipose tissue (WAT) of Wistar rats, leading to rapid and progressive changes in the metabolic profile. The identification of suitable reference genes that are not affected by the experimental conditions is a critical step in accurate normalization of the reverse transcription quantitative real-time PCR (qRT-PCR), a commonly used assay to elucidate changes in the gene expression profile. In the present study, the effects of the cafeteria diet and sympathetic innervation on the gene expression of adrenoceptor beta 3 (Adrb3) from BAT and WAT were assessed using one of the most stable and one of the least stable genes as normalizers. Rats were fed the cafeteria diet and on the 17th day, interscapular BAT or retroperitoneal WAT was denervated and, 7 days after surgery, the contralateral innervated tissue was used as control. Ten reference genes were evaluated (18S, B2m, Actb, CypA, Gapdh, Hprt1, Rpl32, Tbp, Ubc, and Ywhaz) and ranked according to their stability using the following algorithms: geNorm, NormFinder, BestKeeper, and comparative delta threshold cycle (ΔC _t ) method. According to the algorithms employed, the normalization of Adrb3 expression by the least stable genes produced opposite results compared with the most stable genes and literature data. In cafeteria and control diet-fed rats, the three most stable genes were Hprt1, Tbp, and Rpl32 for interscapular BAT and Tbp, B2m, and Hprt1 for retroperitoneal WAT, while the least stable genes were 18S, Actb, and Gapdh for both tissues.

Interleukin-33 reduces neuronal damage and white matter injury via selective microglia M2 polarization after intracerebral hemorrhage in rats

Interleukin-33 (IL-33) is closely related to the regulation of immunological cells, and its receptor ST2 is a member of the interleukin-1 (IL-1) receptor family. Inflammatory responses play critical roles in neuronal damage and white matter injury (WMI) post intracerebral hemorrhage (ICH). In this study, we tried to explore the role of IL-33 in neuronal damage and WMI after ICH and the underlying mechanisms. The in vivo ICH model was performed by autologous whole blood injection into the right basal ganglia in rats. Immunoblotting, immunofluorescence, brain water content measurement, FJB staining, and TUNEL staining were applied in this study. IL-33 expression was increased in whole brain tissues post-ICH, mainly rapidly increased in ipsilateral astrocyte and microglia, but stayed at a low level in neurons. Intracerebroventricular infusion of IL-33 after ICH attenuated short-term and long-term neurological deficits, WMI, neuronal degeneration, cell death and promoted the transformation of microglia phenotype from M1 to M2 in brain tissues after ICH. These results suggest that IL-33 reduces neuronal damage and WMI by promoting microglia M2 polarization after ICH, thereby improving the outcomes of neurological function.

Changes in Nutritional Status Impact Immune Cell Metabolism and Function

Immune cell function and metabolism are closely linked. Many studies have now clearly demonstrated that alterations in cellular metabolism influence immune cell function and that, conversely, immune cell function determines the cellular metabolic state. Less well understood, however, are the effects of systemic metabolism or whole organism nutritional status on immune cell function and metabolism. Several studies have demonstrated that undernutrition is associated with immunosuppression, which leads to both increased susceptibility to infection and protection against several types of autoimmune disease, whereas overnutrition is associated with low-grade, chronic inflammation that increases the risk of metabolic and cardiovascular disease, promotes autoreactivity, and disrupts protective immunity. Here, we review the effects of nutritional status on immunity and highlight the effects of nutrition on circulating cytokines and immune cell populations in both human studies and mouse models. As T cells are critical members of the immune system, which direct overall immune response, we will focus this review on the influence of systemic nutritional status on T cell metabolism and function. Several cytokines and hormones have been identified which mediate the effects of nutrition on T cell metabolism and function through the expression and action of key regulatory signaling proteins. Understanding how T cells are sensitive to both inadequate and overabundant nutrients may enhance our ability to target immune cell metabolism and alter immunity in both malnutrition and obesity.

New perspectives on the regulation of type II inflammation in asthma

Asthma is a chronic inflammatory disease of the lungs which has been thought to arise as a result of inappropriately directed T helper type-2 (Th2) immune responses of the lungs to otherwise innocuous inhaled antigens. Current asthma therapeutics are directed towards the amelioration of downstream consequences of type-2 immune responses (i.e. β-agonists) or broad-spectrum immunosuppression (i.e. corticosteroids). However, few approaches to date have been focused on the primary prevention of immune deviation. Advances in molecular phenotyping reveal heterogeneity within the asthmatic population with multiple endotypes whose varying expression depends on the interplay between numerous environmental factors and the inheritance of a broad range of susceptibility genes. The most common endotype is one described as “type-2-high” (i.e. high levels of interleukin [IL]-13, eosinophilia, and periostin). The identification of multiple endotypes has provided a potential explanation for the observations that therapies directed at typical Th2 cytokines (IL-4, IL-5, and IL-13) and their receptors have often fallen short when they were tested in a diverse group of asthmatic patients without first stratifying based on disease endotype or severity. However, despite the incorporation of endotype-dependent stratification schemes into clinical trial designs, variation in drug responses are still apparent, suggesting that additional genetic/environmental factors may be contributing to the diversity in drug efficacy. Herein, we will review recent advances in our understanding of the complex pathways involved in the initiation and regulation of type-2-mediated immune responses and their modulation by host factors (genetics, metabolic status, and the microbiome). Particular consideration will be given to how this knowledge could pave the way for further refinement of disease endotypes and/or the development of novel therapeutic strategies for the treatment of asthma .