Neutrophil aging exacerbates high fat diet induced metabolic alterations

Consumption of tree nuts as snacks stimulates changes in plasma fatty acid profiles and adipose tissue gene expression in young adults at risk for metabolic syndrome

BACKGROUND AND AIMS

The prevalence of metabolic syndrome has been increasing in young adults, concomitant with the occurrence of increased abdominal adiposity. We previously reported that consuming tree nuts, as replacement for typical high-carbohydrate snacks, reduces visceral fat and waist circumference in young adults who have one or more metabolic syndrome risk factors. We aimed to investigate the effects of tree nuts snack consumption on plasma and adipose tissue fatty acid profiles along with changes in the expression of adipose tissue genes involved in thermogenesis, glycemia, adipocyte signaling, lipolysis, and immunity.

METHODS

A randomized parallel-arm 16-week intervention trial was conducted in 84 adults aged 22-36 years. Participants in both groups were provided with caloric goals for weight maintenance, daily menus, and pre-portioned snacks at every other week visits with study registered dietitians. Changes in dietary fatty acid intakes, plasma and abdominal subcutaneous adipose tissue (SAT) triglycerides fatty acid profiles using gas-liquid chromatography, and the expression of 241 genes in abdominal SAT were evaluated.

RESULTS

Consuming tree nuts snacks increased mono- and polyunsaturated fatty acid intakes yielding a 9-fold greater dietary unsaturated to saturated fat ratio. The tree nuts snack group also had significantly greater improvements in plasma 16:1/16:0 ratio; plasma phospholipids oleic and gamma linolenic acid content; plasma diglycerides, triglycerides, and cholesterol esters oleic acid content; and total plasma monounsaturated fatty acids. While abdominal SAT only showed trends for increased oleic acid content and unsaturated to saturated fat ratio, the tree nuts snacks participants had altered expression of 13 genes in abdominal SAT that have roles in nutrient sensing, energy homeostasis, and vulnerability to obesity.

CONCLUSIONS

Replacing typical high-carbohydrate snacks with tree nuts results in more favorable dietary, plasma, and adipose tissue fatty acid profiles that could aid in preventing the development of excess adiposity and cardiometabolic disease states including metabolic syndrome.

CLINICAL TRIAL REGISTRY

This trial was registered at clinicaltrials.gov NCT03969264.

Bmal1 deficiency in neutrophils alleviates symptoms induced by high-fat diet

Physiological processes, including metabolism and immune responses, are generated by the circadian clock, driven by clock genes. Disrupting circadian rhythms through a high-fat diet promotes obesity and inflammation. Studies show that deleting the clock gene, brain, and muscle ARNT-like 1 (Bmal1) in adipose tissue leads to overeating and weight gain. We now show that Bmal1 deletion in neutrophils protects against diet-induced obesity and reduces inflammatory macrophage infiltration into epididymal white adipose tissue (eWAT), despite increased food intake over 20 weeks of a high-fat diet. This protection is linked to enhanced energy expenditure, increased UCP1 expression in iBAT, improved insulin sensitivity, and altered expression of genes encoding chemokine receptors CXCR2, CXCR4, and the ligand Cxcl2 in eWAT. Our findings reveal a key role of Bmal1 in neutrophils in regulating high-fat diet-induced adipose inflammation and emphasize circadian regulation's importance in immuno-metabolic function.

Identification of key genes in periodontitis

Periodontitis, a prevalent global oral health issue, is primarily characterized by chronic inflammation resulting from bacterial infection. Periodontitis primarily affects the tissues surrounding and supporting the teeth, encompassing the gingival tissue, periodontal attachment apparatus, and the bony socket. The disease mechanism results from intricate interactions between hereditary factors, the body's defense mechanisms, and shifts in the composition of oral microbiota, with each element playing a crucial role in the initiation and advancement of the pathological process. The early symptoms of periodontitis are often not obvious, resulting in patients often not seeking medical attention until they are seriously ill, so finding biomarkers for periodontitis is essential for timely diagnosis and treatment. In this study, we selected two datasets (GSE10334 and GSE16134) by in-depth analysis of publicly available sequencing data of affected and unaffected gum tissue in periodontitis patients in the GEO database. To identify key genes associated with periodontitis pathogenesis and explore potential therapeutic biomarkers, we employed two complementary computational approaches: Random Forest, a robust machine learning algorithm for feature selection, and Weighted Gene Co-expression Network Analysis (WGCNA), a systems biology method for identifying co-expressed gene modules. Through comprehensive analysis of these combined datasets, our objective is to elucidate the underlying molecular pathways governing periodontal disease progression, thereby identifying novel therapeutic targets that may facilitate the design of improved clinical interventions for this condition. This study establishes a substantial scientific foundation that contributes to both clinical applications and fundamental research in periodontitis. The findings not only offer valuable insights for developing early diagnostic strategies and therapeutic interventions but also provide a robust theoretical framework to guide future investigations into the molecular mechanisms underlying this complex disease.

Exploring neutrophils as therapeutic targets in cardiometabolic diseases

Current therapies for diabetes and atherosclerotic cardiovascular diseases (ACVDs) mainly target metabolic risk factors, but often fall short in addressing systemic inflammation, a key driver of disease onset and progression. Advances in our understanding of the biology of neutrophils, the cells that are principally involved in inflammatory situations, have highlighted their pivotal role in cardiometabolic diseases. Yet, neutrophils can reprogram their immune-metabolic functions based on the energetic substrates available, thus influencing both tissue homeostasis and the resolution of inflammation. In this review, we examine the effects of canonical therapies for cardiometabolic diseases on the key molecular pathways through which neutrophils respond to inflammatory stimuli. In addition, we explore potential synergies between these established therapeutic approaches and the anti-inflammatory therapies being evaluated for repurposing in the treatment of cardiometabolic diseases.

ASGR1 deficiency improves atherosclerosis but alters liver metabolism in ApoE-/- mice

The asialoglycoprotein receptor 1 (ASGR1), a multivalent carbohydrate-binding receptor that primarily is responsible for recognizing and eliminating circulating glycoproteins with exposed galactose (Gal) or N-acetylgalactosamine (GalNAc) as terminal glycan residues, has been implicated in modulating the lipid metabolism and reducing cardiovascular disease burden. In this study, we investigated the impact of ASGR1 deficiency (ASGR1-/-) on atherosclerosis by evaluating its effects on plaque formation, lipid metabolism, circulating immunoinflammatory response, and circulating N-glycome under the hypercholesterolemic condition in ApoE-deficient mice. After 16 weeks of a western-type diet, ApoE-/-/ASGR1-/- mice presented lower plasma cholesterol and triglyceride levels compared to ApoE-/-. This was associated with reduced atherosclerotic plaque area and necrotic core formation. Interestingly, ApoE-/-/ASGR1-/- mice showed increased levels of circulating immune cells, increased AST/ALT ratio, and no changes in the N-glycome profile and liver morphology. The liver of ApoE-/-/ASGR1-/- mice, however, presented alterations in the metabolism of lipids, xenobiotics, and bile secretion, indicating broader alterations in liver homeostasis beyond lipids. These data suggest that improvements in circulating lipid metabolism and atherosclerosis in ASGR1 deficiency is paralleled by a deterioration of liver injury. These findings point to the need for additional evaluation before considering ASGR1 as a pharmacological target for dyslipidemia and cardiovascular disorders.

Profiling the impact of anti-human CD20 monoclonal antibodies on lymphocyte B cell subsets and their precursors in the bone marrow and in lymphoid tissues in an immunocompromised mouse engrafted with human cells

Ofatumumab (OFA) and ocrelizumab (OCRE) are two anti-CD20 monoclonal antibodies approved for the treatment of relapsing forms of multiple sclerosis due to their ability to deplete B lymphocytes. The aim of this study was to investigate the impact of these anti-hCD20 antibodies on B lymphocyte subsets in the circulation and in primary and secondary lymphoid organs in an immune system humanized mouse model (immunocompromised Rag2-/-Il2rg-/-CD47-/-) engrafted with human CD34+ hematopoietic stem cells. Three months after humanization, mice, which present adaptive immune cells only of human origin, were treated with OFA (0.3 mg/Kg; day 1, 3 and 5), or OCRE (10 mg/kg; day 1) or saline. Seven days after the last injection a robust (>90 %) decrease of circulating human CD20+ B lymphocytes was observed in both OFA- and OCRE-treated mice. A partial replenishment of B lymphocytes was detectable in blood 36 days from the last injection in OFA-treated mice, while no B lymphocytes could be detected in OCRE-treated mice up to 65 days post injection. Bone marrow profiling showed that during hCD20+ B cell depletion and replenishment, OCRE-treated mice preserved only preB-I cells in the bone marrow, while the bone marrow of OFA-treated mice presented both preB-I as well as preB-II cells, with the latter subset being the one closest to differentiate into immature B cells. These data together with changes in B cell distribution in other tissues suggest that ofatumumab preserve BM niches, critical for B lymphocyte replenishment, limiting potential side effects of the treatment associated with the increased risk of infection.

Dietary fats as regulators of neutrophil plasticity: an update on molecular mechanisms

PURPOSE OF REVIEW

Contemporary guidelines for the prevention of cardio-metabolic diseases focus on the control of dietary fat intake, because of their adverse metabolic effects. Moreover, fats alter innate immune defenses, by eliciting pro-inflammatory epigenetic mechanisms on the long-living hematopoietic cell progenitors which, in the bone marrow, mainly give rise to short-living neutrophils. Nevertheless, the heterogenicity of fats and the complexity of the biology of neutrophils pose challenges in the understanding on how this class of nutrients could contribute to the development of cardio-metabolic diseases via specific molecular mechanisms activating the inflammatory response.

RECENT FINDINGS

The knowledge on the biology of neutrophils is expanding and there are now different cellular networks orchestrating site-specific reprogramming of these cells to optimize the responses against pathogens. The innate immune competence of neutrophil is altered in response to high fat diet and contributes to the development of metabolic alterations, although the precise mechanisms are still poorly understood.

SUMMARY

Defining the different molecular mechanisms involved in the fat-neutrophil crosstalk will help to reconcile the sparse data about the interaction of dietary fats with neutrophils and to tailor strategies to target neutrophils in the context of cardio-metabolic diseases.

High dietary inflammatory index associates with inflammatory proteins in plasma

BACKGROUND AND AIM

Unhealthy dietary habits and highly caloric foods induce metabolic alterations and promote the development of the inflammatory consequences of obesity, insulin resistance, diabetes and cardiovascular diseases. Describing an inflammatory effect of diet is difficult to pursue, owing lacks of standardized quali-quantitative dietary assessments. The Dietary Inflammatory Index (DII) has been proposed as an estimator of the pro- or anti-inflammatory effect of nutrients and higher DII values, which indicate an increased intake of nutrients with pro-inflammatory effects, relate to an increased risk of metabolic and cardiovascular diseases and we here assessed whether they reflect biologically relevant plasmatic variations of inflammatory proteins.

METHODS

In this cross-sectional study, seven days dietary records from 663 subjects in primary prevention for cardiovascular diseases were analyzed to derive the intake of nutrients, foods and to calculate DII. To associate DII with the Normalized Protein eXpression (NPX), an index of abundance, of a targeted panel of 368 inflammatory biomarkers (Olink™) measured in the plasma, we divided the population by the median value of DII (1.60 (0.83-2.30)).

RESULTS

332 subjects with estimated DII over the median value reported a higher intake of saturated fats but lower intakes of poly-unsaturated fats, including omega-3 and omega-6 fats, versus subjects with estimated dietary DII below the median value (N = 331). The NPX of 61 proteins was increased in the plasma of subjects with DII > median vs. subjects with DII < median. By contrast, in the latter group, we underscored only 3 proteins with increased NPX. Only 23, out of these 64 proteins, accurately identified subjects with DII > median (Area Under the Curve = 0.601 (0.519-0.668), p = 0.035).

CONCLUSION

This large-scale proteomic study supports that higher DII reflects changes in the plasmatic abundance of inflammatory proteins. Larger studies are warranted to validate.

ASGR1 deficiency diverts lipids toward adipose tissue but results in liver damage during obesity

BACKGROUND

Asialoglycoprotein receptor 1 (ASGR1), primarily expressed on hepatocytes, promotes the clearance and the degradation of glycoproteins, including lipoproteins, from the circulation. In humans, loss-of-function variants of ASGR1 are associated with a favorable metabolic profile and reduced incidence of cardiovascular diseases. The molecular mechanisms by which ASGR1 could affect the onset of metabolic syndrome and obesity are unclear. Therefore, here we investigated the contribution of ASGR1 in the development of metabolic syndrome and obesity.

METHODS

ASGR1 deficient mice (ASGR1-/-) were subjected to a high-fat diet (45% Kcal from fat) for 20 weeks. The systemic metabolic profile, hepatic and visceral adipose tissue were characterized for metabolic and structural alterations, as well as for immune cells infiltration.

RESULTS

ASGR1-/- mice present a hypertrophic adipose tissue with 41% increase in fat accumulation in visceral adipose tissue (VAT), alongside with alteration in lipid metabolic pathways. Intriguingly, ASGR1-/- mice exhibit a comparable response to an acute glucose and insulin challenge in circulation, coupled with notably decreased in circulating cholesterol levels. Although the liver of ASGR1-/- have similar lipid accumulation to the WT mice, they present elevated levels of liver inflammation and a decrease in mitochondrial function.

CONCLUSION

ASGR1 deficiency impacts energetic homeostasis during obesity leading to improved plasma lipid levels but increased VAT lipid accumulation and liver damage.

CXCR2 chemokine receptor - a master regulator in cancer and physiology

Recent findings have modified our understanding of the roles of chemokine receptor CXCR2 and its ligands in cancer, inflammation, and immunity. Studies in Cxcr2 tissue-specific knockout mice show that this receptor is involved in, among other things, cancer, central nervous system (CNS) function, metabolism, reproduction, COVID-19, and the response to circadian cycles. Moreover, CXCR2 involvement in neutrophil function has been revisited not only in physiology but also for its major contribution to cancers. The recent unfolding of the role of CXCR2 in numerous cancers has led to extensive evaluation of multiple CXCR2 antagonists in preclinical and clinical studies. In this review we discuss the potential of targeting CXCR2 for cancer treatment.