IL-20 is involved in obesity by modulation of adipogenesis and macrophage dysregulation

Novel perspectives on autophagy-oxidative stress-inflammation axis in the orchestration of adipogenesis

Adipose tissue, an indispensable organ, fulfils the pivotal role of energy storage and metabolism and is instrumental in maintaining the dynamic equilibrium of energy and health of the organism. Adipocyte hypertrophy and adipocyte hyperplasia (adipogenesis) are the two primary mechanisms of fat deposition. Mature adipocytes are obtained by differentiating mesenchymal stem cells into preadipocytes and redifferentiation. However, the mechanisms orchestrating adipogenesis remain unclear. Autophagy, an alternative cell death pathway that sustains intracellular energy homeostasis through the degradation of cellular components, is implicated in regulating adipogenesis. Furthermore, adipose tissue functions as an endocrine organ, producing various cytokines, and certain inflammatory factors, in turn, modulate autophagy and adipogenesis. Additionally, autophagy influences intracellular redox homeostasis by regulating reactive oxygen species, which play pivotal roles in adipogenesis. There is a growing interest in exploring the involvement of autophagy, inflammation, and oxidative stress in adipogenesis. The present manuscript reviews the impact of autophagy, oxidative stress, and inflammation on the regulation of adipogenesis and, for the first time, discusses their interactions during adipogenesis. An integrated analysis of the role of autophagy, inflammation and oxidative stress will contribute to elucidating the mechanisms of adipogenesis and expediting the exploration of molecular targets for treating obesity-related metabolic disorders.

The role of interleukin-20 in liver disease: Functions, mechanisms and clinical applications

Liver disease is a severe public health concern worldwide. There is a close relationship between the liver and cytokines, and liver inflammation from a variety of causes leads to the release and activation of cytokines. The functions of cytokines are complex and variable, and are closely related to their cellular origin, target molecules and mode of action. Interleukin (IL)-20 has been studied as a pro-inflammatory cytokine that is expressed and regulated in some diseases. Furthermore, accumulating evidences has shown that IL-20 is highly expressed in clinical samples from patients with liver disease, promoting the production of pro-inflammatory molecules involved in liver disease progression, and antagonists of IL-20 can effectively inhibit liver injury and produce protective effects. This review highlights the potential of targeting IL-20 in liver diseases, elucidates the potential mechanisms of IL-20 inducing liver injury, and suggests multiple viable strategies to mitigate the pro-inflammatory response to IL-20. Genomic CRISPR/Cas9-based screens may be a feasible way to further explore the signaling pathways and regulation of IL-20 in liver diseases. Nanovector systems targeting IL-20 offer new possibilities for the treatment and prevention of liver diseases.

Impact of obesity on airway remodeling in asthma: pathophysiological insights and clinical implications

The prevalence of obesity among asthma patients has surged in recent years, posing a significant risk factor for uncontrolled asthma. Beyond its impact on asthma severity and patients' quality of life, obesity is associated with reduced lung function, increased asthma exacerbations, hospitalizations, heightened airway hyperresponsiveness, and elevated asthma-related mortality. Obesity may lead to metabolic dysfunction and immune dysregulation, fostering chronic inflammation characterized by increased pro-inflammatory mediators and adipocytokines, elevated reactive oxygen species, and reduced antioxidant activity. This chronic inflammation holds the potential to induce airway remodeling in individuals with asthma and obesity. Airway remodeling encompasses structural and pathological changes, involving alterations in the airway's epithelial and subepithelial layers, hyperplasia and hypertrophy of airway smooth muscle, and changes in airway vascularity. In individuals with asthma and obesity, airway remodeling may underlie heightened airway hyperresponsiveness and increased asthma severity, ultimately contributing to the development of persistent airflow limitation, declining lung function, and a potential increase in asthma-related mortality. Despite efforts to address the impact of obesity on asthma outcomes, the intricate mechanisms linking obesity to asthma pathophysiology, particularly concerning airway remodeling, remain incompletely understood. This comprehensive review discusses current research investigating the influence of obesity on airway remodeling, to enhance our understanding of obesity's role in the context of asthma airway remodeling.

Deciphering the Receptor-Mediated Signaling Pathways of Interleukin-19 and Interleukin-20

Interleukin-19 (IL-19) and Interleukin-20 (IL-20) are inflammatory cytokines belonging to the IL-10 family with immunoregulatory properties. Emerging evidence highlights the importance of association of these cytokines with both immunological and inflammatory disorders, including chronic inflammation, cardiac dysfunction, and cancer. IL-19 and IL-20 bind to the heterodimeric receptor complex and induce multiple downstream signaling cascades by activating the signal transducer and activator of transcription 3 (STAT3), Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), AKT serine/threonine kinase 1 (AKT1), and NFKB inhibitor alpha (NFKBIA), leading to proinflammatory and anti-inflammatory reactions in cancer, inflammation, tumor microenvironment, and infectious diseases. Considering the significant role of these cytokines, we integrated its cellular signaling network by combining multiomics molecular events associated with 56 molecules of induced by IL-19 and 156 molecules of by IL-20. The reactions of these signaling events are classified into enzyme catalysis/post-translational modifications, activation/inhibition events, molecular associations, gene regulations at the mRNA and protein level, and the protein translocation events. We believe that this signaling pathway map would serve as a knowledge base, that aid researchers and clinicians to understand and explore the intricate mechanisms and identify novel signaling components and therapeutic targets for diseases associated with dysregulated IL-19 and IL-20 signaling.

Manipulation of osteogenic and adipogenic differentiation of human degenerative disc and ligamentum flavum derived progenitor cells using IL-1β, IL-19, and IL-20

PURPOSE

To elucidate whether pro-inflammatory cytokines might influence the commitment of intervertebral disc (IVD)- and ligamentum flavum (LF)-derived progenitor cells toward either osteogenesis or adipogenesis, specifically Interleukin-1β (IL-1β), IL-19, and IL-20.

METHODS

Sixty patients with degenerative spondylolisthesis and lumbar or lumbosacral spinal stenosis were included in the study. Injuries to the spine, infections, and benign or malignant tumors were excluded. From nine patient samples, IVD- and LF-derived cells were isolated after primary culture, and two clinical samples were excluded due to mycoplasma infection. The effects of IL-1β, IL-19, as well as IL-20 in regulating osteogenic and adipogenic differentiation in vitro were investigated.

RESULTS

Primary IVD- and LF-derived cells were found to have a similar cell morphology and profile of surface markers (CD44, CD90, and CD105) as placenta-derived mesenchymal stem cells (MSCs). Primary IVD/LF cells have a high capacity to differentiate into osteocytes and adipocytes. IL-19 had a tendency to promote adipogenesis. IL-20 inhibited osteogenesis and promoted adipogenesis; IL-1β promoted osteogenesis but inhibited adipogenesis.

CONCLUSION

IL-1β, IL-19, and IL-20 impact the adipogenic and osteogenic differentiation of IVD-derived and LF-derived cells. Modulating the expression of IL-1β, IL-19, and IL-20 provides a potential avenue for controlling cell differentiation of IVD- and LF-derived cells, which might have beneficial effect for degenerative spondylolisthesis and spinal stenosis.

Neonatal cytokines associated with infant overweight and obesity at 1 year of age

OBJECTIVE

The incidence of childhood overweight and obesity has been increasing in recent years. Immune dysregulation has been demonstrated as a condition related to childhood obesity. Whether the neonatal immune status is related to infant overweight and obesity at 1 year of age is unclear.

METHODS

To explore the relationship between neonatal cytokines and infant overweight and obesity, we conducted a prospective study in Suzhou Municipal Hospital Affiliated to Nanjing Medical University from 2015 to 2016. 514 neonates were recruited and their dried blood spots were collected after birth. Infants were grouped into normal size groups and overweight and obesity groups based on BMI at 1 year of age. 27 neonatal cytokines levels were compared between the two groups.

RESULTS

370 infants were included in final analysis. Granulocyte colony stimulating factor (GCSF), interleukin-17A (IL17A) and platelet derived growth factor-BB (PDGF-BB) levels were independently associated with childhood overweight and obesity (OR =1.27, 95%CI 1.03, 1.57; OR =1.29, 95%CI: 1.06, 1.60; OR =0.69, 95%CI: 0.49, 0.96). Additionally, neonatal GCSF and IL17A levels were positively associated with increased BMI (β = 0.11, 95%CI: 0.02, 0.19; β = 0.07, 95%CI 0.01, 013) and BMI z-scores (β = 0.10, 95%CI: 0.02, 0.18; β = 0.06, 95%CI 0.01, 0.13). Neonatal PDGF-BB levels were negatively associated with BMI (β = -0.12, 95%CI: -0.23, -0.01) and BMI z-scores (β = -0.12, 95%CI: -0.23, -0.01). The inverse probability weighting (IPW) was performed to account for potential selection bias of this study, and the results were consistent with the above mentioned findings.

CONCLUSIONS

Neonatal GCSF, IL17A and PDGF-BB levels were correlated with infant overweight and obesity at 1 year of age, suggesting that early life immune status play a significant role of late obesity.

Recent Advances in the Knowledge of the Mechanisms of Leptin Physiology and Actions in Neurological and Metabolic Pathologies

Excess body weight is frequently associated with low-grade inflammation. Evidence indicates a relationship between obesity and cancer, as well as with other diseases, such as diabetes and non-alcoholic fatty liver disease, in which inflammation and the actions of various adipokines play a role in the pathological mechanisms involved in these disorders. Leptin is mainly produced by adipose tissue in proportion to fat stores, but it is also synthesized in other organs, where leptin receptors are expressed. This hormone performs numerous actions in the brain, mainly related to the control of energy homeostasis. It is also involved in neurogenesis and neuroprotection, and central leptin resistance is related to some neurological disorders, e.g., Parkinson's and Alzheimer's diseases. In peripheral tissues, leptin is implicated in the regulation of metabolism, as well as of bone density and muscle mass. All these actions can be affected by changes in leptin levels and the mechanisms associated with resistance to this hormone. This review will present recent advances in the molecular mechanisms of leptin action and their underlying roles in pathological situations, which may be of interest for revealing new approaches for the treatment of diseases where the actions of this adipokine might be compromised.

New Insights into Molecular Mechanisms of Chronic Kidney Disease

Chronic kidney disease (CKD) is a major public health problem with a developing incidence and prevalence. As a consequence of the growing number of patients diagnosed with renal dysfunction leading to the development of CKD, it is particularly important to explain the mechanisms of its underlying causes. In our paper, we discuss the molecular mechanisms of the development and progression of CKD, focusing on oxidative stress, the role of the immune system, neutrophil gelatinase-associated lipocalin, and matrix metalloproteinases. Moreover, growing evidence shows the importance of the role of the gut-kidney axis in the maintenance of normal homeostasis and of the dysregulation of this axis in CKD. Further, we discuss the therapeutic potential and highlight the future research directions for the therapeutic targeting of CKD. However, additional investigation is crucial to improve our knowledge of CKD progression and, more importantly, accelerate basic research to improve our understanding of the mechanism of pathophysiology.

Netrin-1 Promotes Visceral Adipose Tissue Inflammation in Obesity and Is Associated with Insulin Resistance

Netrin (NTN)-1 exhibits pro- and anti-inflammatory roles in different settings, playing important roles in the obesity-associated low-grade chronic inflammation. We aimed to determine the impact of NTN-1 on obesity and obesity-associated type 2 diabetes, as well as its role in visceral adipose tissue (VAT) inflammation. A total of 91 subjects were enrolled in this case-control study. Circulating levels of NTN-1 and its receptor neogenin (NEO)-1 were determined before and after weight loss achieved by caloric restriction and bariatric surgery. mRNA levels of NTN1 and NEO1 were assessed in human VAT, liver, and peripheral blood mononuclear cells. In vitro studies in human visceral adipocytes and human monocytic leukemia cells (THP-1)-derived macrophages were performed to analyze the impact of inflammation-related mediators on the gene expression levels of NTN1 and its receptor NEO1 as well as the effect of NTN-1 on inflammation. Increased (p < 0.001) circulating concentrations of NTN-1 in obesity decreased (p < 0.05) after diet-induced weight loss being also associated with a reduction in glucose (p < 0.01) and insulin levels (p < 0.05). Gene expression levels of NTN1 and NEO1 were upregulated (p < 0.05) in the VAT from patients with obesity with the highest expression in the stromovascular fraction cells compared with mature adipocytes (p < 0.01). NTN1 expression levels were enhanced (p < 0.01) under hypoxia and by inflammatory factors in both adipocytes and macrophages. Adipocyte-conditioned media strongly upregulated (p < 0.001) the mRNA levels of NTN1 in macrophages. The treatment of adipocytes with NTN-1 promoted the upregulation (p < 0.05) of pro-inflammatory and chemotactic molecules as well as its receptor NEO1. Collectively, these findings suggest that NTN-1 regulates VAT chronic inflammation and insulin resistance in obesity.

Interleukin-20 is involved in dry eye disease and is a potential therapeutic target

Background

Dry eye disease (DED) is a common disease in ophthalmology, affecting millions of people worldwide. Recent studies have shown that inflammation is the core mechanism of DED. IL-20 is a proinflammatory cytokine involved in various inflammatory diseases. Therefore, we aimed to explore the role of this cytokine in the pathogenesis of DED and evaluate the therapeutic potential of the anti-IL-20 monoclonal antibody (mAb) 7E for DED treatment.

Methods

Clinical tear samples from patients with DED and non-DED controls were collected and their IL-20 protein levels were determined. We established three DED animal models to explore the role of IL-20 and the efficacy of IL-20 antibody in DED. Benzalkonium chloride (BAC)-induced over-evaporative DED, extra-orbital lacrimal gland excision (LGE)-induced aqueous tear-deficient DED, and desiccating stress (DS)-induced combined over-evaporative and aqueous tear-deficient DED animal models were established to investigate the role of IL-20. The anti-IL-20 antibody 7E was established to neutralize IL-20 activity. The effects of IL-20 or 7E on human corneal epithelial cells and macrophages under hyperosmotic stress were analyzed. 7E was topically applied to eyes to evaluate the therapeutic effects in the DED animal models.

Results

IL-20 was significantly upregulated in the tears of patients with DED and in the tears and corneas of DED animal models. Under hyperosmotic stress, IL-20 expression was induced via NFAT5 activation in corneal epithelial cells. 7E suppressed hyperosmotic stress-induced activation of macrophages. IL-20 induced cell death in corneal epithelial cells and 7E protected cells from hyperosmotic stress-induced cell death. Blocking IL-20 signaling with 7E protected mice from BAC-induced, LGE-induced, and DS-induced DED by reducing DED symptoms and inhibiting inflammatory responses, macrophage infiltration, apoptosis, and Th17 populations in the conjunctiva and draining lymph nodes.

Conclusions

Our results demonstrated the functions of IL-20 in DED and presented a potential therapeutic option for this condition.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00821-2.

IL-20 is involved in obesity by modulation of adipogenesis and macrophage dysregulation

IL-20 is a proinflammatory cytokine of the IL-10 family and involved in several diseases. However, the regulatory role of IL-20 in obesity is not well understood. We explored the function of IL-20 in the pathogenesis of obesity-induced insulin resistance by ELISA, Western blotting and flow cytometry. The therapeutic potential of IL-20 monoclonal antibody 7E for ameliorating diet-induced obesity was analysed in murine models. Higher serum IL-20 levels were detected in obese patients. It was upregulated in leptin-deficient (ob/ob), leptin-resistant (db/db) and high-fat diet (HFD)-induced murine obesity models. In vitro, IL-20 regulated the adipocyte differentiation and the polarization of bone marrow-derived macrophages into proinflammatory M1 type. It also caused inflammation and macrophage retention in adipose tissues by upregulating TNF-α, monocyte chemotactic protein 1 (MCP-1), netrin 1 and unc5b (netrin receptor) expression in macrophages and netrin 1, leptin and MCP-1 in adipocytes. IL-20 promoted insulin resistance by inhibiting glucose uptake in mature adipocytes through the SOCS-3 pathway. In HFD-induced obesity in mice, 7E treatment reduced body weight and improved glucose tolerance and insulin sensitivity; it also reduced local inflammation and the number of M1-like macrophages in adipose tissues. We have identified a critical role of IL-20 in obesity-induced inflammation and insulin resistance, and we conclude that IL-20 may be a novel target for treating obesity and insulin resistance in patients with metabolic disorders.