Adipocyte-Secreted IL-6 Sensitizes Macrophages to IL-4 Signaling

Unveiling the role of miR-186 in SIRT1 regulation in adipocytes: implications for adipogenesis and inflammation in obesity

Objectives

MicroRNAs (miRNAs) play a crucial role in the onset and progress of obesity. The inflammation of adipose tissue is deemed causative of the complications associated with obesity. This study delved into the potential mechanisms of miRNA-mediated SIRT1 regulation and inflammatory factors modulation in 3T3-L1 cells.

Methods

3T3-L1 cells were differentiated into mature and hypertrophied adipocytes and the expression of selected miRNAs was evaluated by real-time PCR. 3T3-L1 cells were transfected with the mimic and inhibitor sequences of miR-186, together with the appropriate controls. Western blot analysis assessed the expression level of SIRT1 protein, and the interaction between miR-186 and SIRT1 was scrutinized through a luciferase reporter gene assay.

Results

Across all the mature and hypertrophied cells, the evaluated miRNAs exhibited a significant increase in expression, highlighting their involvement in fat accumulation at a cellular scale. Notably, miR-186-5p displayed the highest expression in differentiated cells and the hypertrophy model. Induction of miR-186 led to attenuation of SIRT1, while its inhibition by miR-186 inhibitor resulted in upregulation of SIRT1 expression. miR-186 caused a remarkable elevation in the expression of inflammatory genes, including IL-6, IL-1β, TNF-α, and MCP-1, indicating a noticeable pattern of relationship between miR-186-induced SIRT-1 inhibition and inflammation.

Conclusions

miR-186 emerges as a pivotal factor in amplifying inflammatory cytokines and down-regulates SIRT1, an effect that might highlight the involvement of SIRT1 in the inflammatory responses of adipocytes, as well as underscoring the crucial role of miR-186 in this process. These findings present miR-186 as a promising target for addressing health challenges related to obesity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01525-0.

Recent advances in targeting obesity, with a focus on TGF-β signaling and vagus nerve innervation

Over a third of the global population is affected by obesity, fatty liver disease (Metabolic Dysfunction-Associated Steatotic Liver Disease, MASLD), and its severe form, MASH (Metabolic Dysfunction-Associated Steatohepatitis), which can ultimately progress to hepatocellular carcinoma (HCC). Recent advancements include therapeutics such as glucagon-like peptide 1 (GLP-1) agonists and neural/vagal modulation strategies for these disorders. Among the many pathways regulating these conditions, emerging insights into transforming growth factor-β (TGF-β) signaling highlight potential future targets through its role in pathophysiological processes such as adipogenesis, inflammation, and fibrosis. Vagus nerve innervation in the gastrointestinal tract is involved in satiety regulation and energy homeostasis, and vagus nerve stimulation has been applied in weight loss and diabetes. This review explores clinical trials in obesity, novel therapeutic targets, and the role of TGF-β signaling and vagus nerve modulation in obesity-related liver diseases and HCC.

Association between atherogenic index of plasma and future risk of cardiovascular disease in individuals with cardiovascular-kidney-metabolic syndrome stages 0-3: a nationwide prospective cohort study

BACKGROUND

As an emerging concept, Cardiovascular-kidney-metabolic syndrome (CKM) elucidates the intricate interconnection between metabolic disorders(Mets), cardiovascular disease(CVD), and chronic kidney disease(CKD). Within this context, while numerous studies have demonstrated a correlation between the Atherogenic Index of Plasma (AIP) and CVD, the precise relationship between long-term fluctuations in the AIP and the incidence of CVD in patients with CKM syndrome remains unclear.

METHOD

The CKM stages 0-3 population was obtained from the China Health and Retirement Longitudinal Study (CHARLS). The outcome CVD was defined as self-reported heart disease and/or stroke. AIP control level was classified using k-mean cluster analysis. Logistic regression was used to analyse the effect of cumulative AIP (cumAIP) on the incidence of CVD. Restricted cubic spline models (RCS) were used to explore the potential non-linear relationship between cumulative AIP and CVD risk at different CKM syndrome stages.

RESULTS

Of the 3429 CKM stages 0-3 participants, 620 patients developed CVD during the 3-year follow-up period. After adjusting for various confounders, the odds ratio (OR) for the well-controlled class 2 compared with the best AIP control class 1 were 1.37 (1.04, 1.81), the OR for the moderately-controlled class 3 were 1.54 (95% CI, 1.04-2.26), the poorly-controlled class 4 were 1.65 (95% CI, 1.13-2.41), and the worst-controlled class 5 were 2.14 (95% CI, 1.15-3.97). In restricted cubic spline regression analyses, changes in AIP were linearly associated with the occurrence of CVD events. Further weighted quartiles and regression analyses indicated that triglyceride(TG) was a key variable for AIP in predicting CVD events in the CKM stages 0-3 population.

CONCLUSIONS

Poor control level of AIP are associated with an increased risk of CVD events in the population of CKM stages 0-3. Long-term dynamic monitoring of changes in AIP may help in the early identification of patients at high risk of developing CVD in the individuals with CKM stages 0-3.

The association between composite dietary antioxidant index and rheumatoid arthritis: evidence from NHANES 2001-2020

BACKGROUND

This study aimed to investigate the relationship between the composite dietary antioxidant index (CDAI) and rheumatoid arthritis (RA) using data from the National Health and Nutrition Examination Survey (NHANES) spanning from 2001 to 2020.

METHODS

CDAI is based on the intake of vitamins A, C, E, manganese, selenium, and zinc from the diet. RA patients were identified through questionnaire responses. Weighted multivariate regression analysis was employed to examine the association between CDAI and RA. Additionally, restricted cubic splines were utilized to assess potential non-linear relationships. Subgroup analyses were used to explore whether the relationship between CDAI and RA remained consistent across subgroups (e.g., sex, age, smoking status, etc.). We also used interaction terms to assess whether these subgroup variables influence the relationship between CDAI and RA risk. Finally, we also performed sensitivity analyses to assess the robustness of the main findings after excluding patients with a history of diabetes.

RESULTS

The study included a total of 11,266 patients. After adjusting for all covariates, the multivariate logistic regression analysis showed that each unit increase in CDAI was associated with a 4% reduction in the odds of RA (odds ratio = 0.96, 95% confidence interval = 0.94-0.99). The incidence of RA was found to decrease as CDAI levels increased (P for trend < 0.05). In the restricted cubic spline analysis, a linear relationship between CDAI and RA was observed. Subgroup analyses and interactions demonstrated that the negative association between CDAI and RA was consistent across all subgroups and was influenced by smoking.

CONCLUSION

This study indicates a negative correlation between CDAI and RA, suggesting that CDAI may serve as a valuable and convenient marker for reducing the risk of RA in US adults.

CLINICAL TRIAL NUMBER

Not applicable.

Thermogenic Adipocytes Promote M2 Macrophage Polarization through CNNM4-Mediated Mg Secretion

M2 macrophages promote adipose tissue thermogenesis which dissipates energy in the form of heat to combat obesity. However, the regulation of M2 macrophages by thermogenic adipocytes is unclear. Here, it is identified magnesium (Mg) as a thermogenic adipocyte-secreted factor to promote M2 macrophage polarization. Mg transporter Cyclin and CBS domain divalent metal cation transport mediator 4 (CNNM4) induced by ADRB3-PKA-CREB signaling in thermogenic adipocytes during cold exposure mediates Mg efflux and Mg in turn binds to the DFG motif in mTOR to facilitate mTORC2 activation and M2 polarization in macrophages. In obesity, downregulation of CNNM4 expression inhibits Mg secretion from thermogenic adipocytes, which leads to decreased M2 macrophage polarization and thermogenesis. As a result, CNNM4 overexpression in adipocytes or Mg supplementation in adipose tissue ameliorates obesity by promoting thermogenesis. Importantly, an Mg wire implantation (AMI) approach is introduced to achieve adipose tissue-specific long-term Mg supplement. AMI promotes M2 macrophage polarization and thermogenesis and ameliorates obesity in mice. Taken together, a reciprocal regulation of thermogenic adipocytes and M2 macrophages important for thermogenesis is identified, and AMI is offered as a promising strategy against obesity.

Oxygen, angiogenesis, cancer and immune interplay in breast tumour microenvironment: a computational investigation

Breast cancer is a challenging global health problem among women. This study investigates the intricate breast tumour microenvironment (TME) dynamics utilizing data from mammary-specific polyomavirus middle T antigen overexpression mouse models (MMTV-PyMT). It incorporates endothelial cells (ECs), oxygen and vascular endothelial growth factors (VEGF) to examine the interplay of angiogenesis, hypoxia, VEGF and immune cells in cancer progression. We introduce an approach to impute immune cell fractions within the TME using single-cell RNA-sequencing (scRNA-seq) data from MMTV-PyMT mice. We quantify our analysis by estimating cell counts using cell size data and laboratory findings from existing literature. We perform parameter estimation via a Hybrid Genetic Algorithm (HGA). Our simulations reveal various TME behaviours, emphasizing the critical role of adipocytes, angiogenesis, hypoxia and oxygen transport in driving immune responses and cancer progression. Global sensitivity analyses highlight potential therapeutic intervention points, such as VEGFs' role in EC growth and oxygen transportation and severe hypoxia's effect on cancer and the total number of cells. The VEGF-mediated production rate of ECs shows an essential time-dependent impact, highlighting the importance of early intervention in slowing cancer progression. These findings align with clinical observations demonstrating the VEGF inhibitors' efficacy and suggest a timely intervention for better outcomes.

Molecular mechanisms of obesity predisposes to atopic dermatitis

Obesity is a prevalent metabolic disease that reduces bacterial diversity, colonizes the epidermis with lipophilic bacteria, and increases intestinal pro-inflammatory species, all of which lead to impaired epithelial barriers. Adipose tissue secretes immunomodulatory molecules, such as adipokines, leptin, and adiponectin, which alters the morphology of adipocytes and macrophages as well as modulates T cell differentiation and peripheral Th2-dominated immune responses. Atopic dermatitis (AD) and obesity have similar pathological manifestations, including inflammation as well as insulin and leptin resistance. This review examines the major mechanisms between obesity and AD, which focus on the effect on skin and gut microbiota, immune responses mediated by the toll like receptor (TLR) signaling pathway, and changes in cytokine levels (TNF-a, IL-6, IL-4, and IL13). Moreover, we describe the potential effects of adipokines on AD and finally mechanisms by which PPAR-γ suppresses and regulates type 2 immunity.

Cell-cell crosstalk between fat cells and immune cells

Obesity is a metabolic disorder with pandemic-like implications, lacking viable pharmaceutical treatments currently. Thermogenic adipose tissues, including brown and beige adipose tissues, play an essential role in regulating systemic energy homeostasis and have emerged as appealing therapeutic targets for the treatment of obesity and obesity-related diseases. The function of adipocytes is subject to complex regulation by a cellular network of immune signaling pathways in response to environmental signals. However, the specific regulatory roles of immune cells in thermogenesis and relevant involving mechanisms are still not well understood. Here, we concentrate on our present knowledge of the interaction between thermogenic adipocytes and immune cells and present an overview of cellular and molecular mechanisms underlying immunometabolism in adipose tissues. We discuss cytokines, especially interleukins, which originate from widely variable sources, and their impacts on the development and function of thermogenic adipocytes. Moreover, we summarize the neuroimmune regulation in heat production and expand a new mode of intercellular communication mediated by mitochondrial transfer. The crosstalk between immune cells and adipocytes achieves adipose tissue homeostasis and systemic energy balance. A deep understanding of this intricate interaction would provide evidence for improving thermogenic efficiency by remodeling the immune microenvironment. Interventions based on these factors show a high potential to prevent adverse metabolic outcomes in patients with obesity.

Plasma levels of adipokines and insulin are associated with markers of brain atrophy and cognitive decline in the spectrum of Alzheimer's Disease

The discovery that metabolic alterations often coexist with neurodegenerative conditions has sparked interest in the examination of metabolic regulatory factors as potential modulators of brain health. Here, we examined the role of adipokines (leptin, adiponectin, resistin, and IL6) and insulin on different markers of brain atrophy in participants on the spectrum of Alzheimer's Disease. We included 566 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset with 1063 follow-up time points (average follow-up: one year); and examined the association between metabolic regulatory factors and volumetric MRI values, white matter hyperintensities, and measures of cognitive impairment. Higher leptin, resistin, IL6, and insulin were associated with markers of cerebral atrophy, such as lower total brain volume, or higher ventricular volume. Higher leptin and resistin were also associated with greater impairment in daily life activities. Higher adiponectin was associated with lower ventricle volume. There was no association between adipokines or insulin with white matter hyperintensities. Our findings indicate a co-occurrence between alterations in metabolic regulatory factors and in brain volume along the preclinical to clinical spectrum of Alzheimer's Disease. These results suggest that strategies aimed at promoting metabolic health may positively impact brain health.

The Role of IL-6 in Neurodegenerative Disorders

"Neurodegenerative disorder" is an umbrella term for a group of fatal progressive neurological illnesses characterized by neuronal loss and inflammation. Interleukin-6 (IL-6), a pleiotropic cytokine, significantly affects the activities of nerve cells and plays a pivotal role in neuroinflammation. Furthermore, as high levels of IL-6 have been frequently observed in association with several neurodegenerative disorders, it may potentially be used as a biomarker for the progression and prognosis of these diseases. This review summarizes the production and function of IL-6 as well as its downstream signaling pathways. Moreover, we make a comprehensive review on the roles of IL-6 in neurodegenerative disorders and its potential clinical application.

Targeting different phenotypes of macrophages: A potential strategy for natural products to treat inflammatory bone and joint diseases

BACKGROUND

Macrophages, a key class of immune cells, have a dual role in inflammatory responses, switching between anti-inflammatory M2 and pro-inflammatory M1 subtypes depending on the specific environment. Greater numbers of M1 macrophages correlate with increased production of inflammatory chemicals, decreased osteogenic potential, and eventually bone and joint disorders. Therefore, reversing M1 macrophages polarization is advantageous for lowering inflammatory factors. To better treat inflammatory bone disorders in the future, it may be helpful to gain insight into the specific mechanisms and natural products that modulate macrophage polarization.

OBJECTIVE

This review examines the impact of programmed cell death and different cells in the bone microenvironment on macrophage polarization, as well as the effects of natural products on the various phenotypes of macrophages, in order to suggest some possibilities for the treatment of inflammatory osteoarthritic disorders.

METHODS

Using 'macrophage polarization,' 'M1 macrophage' 'M2 macrophage' 'osteoporosis,' 'osteonecrosis of femoral head,' 'osteolysis,' 'gouty arthritis,' 'collagen-induced arthritis,' 'freund's adjuvant-induced arthritis,' 'adjuvant arthritis,' and 'rheumatoid arthritis' as search terms, the relevant literature was searched using the PubMed, the Cochrane Library and Web of Science databases.

RESULTS

Targeting macrophages through different signaling pathways has become a key mechanism for the treatment of inflammatory bone and joint diseases, including HIF-1α, NF-κB, AKT/mTOR, JAK1/2-STAT1, NF-κB, JNK, ERK, p-38α/β, p38/MAPK, PI3K/AKT, AMPK, AMPK/Sirt1, STAT TLR4/NF-κB, TLR4/NLRP3, NAMPT pathway, as well as the programmed cell death autophagy, pyroptosis and ERS.

CONCLUSION

As a result of a search of databases, we have summarized the available experimental and clinical evidence supporting herbal products as potential treatment agents for inflammatory osteoarthropathy. In this paper, we outline the various modulatory effects of natural substances targeting macrophages in various diseases, which may provide insight into drug options and directions for future clinical trials. In spite of this, more mechanistic studies on natural substances, as well as pharmacological, toxicological, and clinical studies are required.

Signaling pathways and intervention for therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.

Obesity contributes to hepatocellular carcinoma development via immunosuppressive microenvironment remodeling

It is generally recognized that the initiation of obesity-related hepatocellular carcinoma (HCC) is closely associated with hepatic inflammation. However, the paradoxical role of inflammation in the initiation and progression of HCC is highlighted by the fact that the inflammatory HCC is accompanied by significant immune effector cells infiltration compared to non-inflammatory HCC and HCC with enhanced immune response exhibits better survival. Importantly, the cancer progression has been primarily attributed to the immunosuppression, which can also be induced by obesity. Furthermore, the increased risk of viral infection and thus viral-HCC in obese individuals supports the view that obesity contributes to HCC via immunosuppression. Here, we have reviewed the various mechanisms responsible for obesity-induced tumor immune microenvironment and immunosuppression in obesity-related HCC. We highlight that the obesity-induced immunosuppression originates from lipid disorder as well as metabolic reprogramming and propose potential therapeutic strategy for HCC based on the current success of immunotherapy.