Neutrophil aging exacerbates high fat diet induced metabolic alterations

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.