Interleukin-20 targets podocytes and is upregulated in experimental murine diabetic nephropathy

The effect of interleukin-20 on periodontal tissue destruction in individuals with periodontitis

BACKGROUND AND OBJECTIVE

Periodontitis is an inflammatory disease that destroys periodontal tissues. Interleukin-20 (IL-20), on the other hand, is known as a potent angiogenic, chemotactic, and pro-inflammatory cytokine associated with various chronic inflammatory disorders. IL-20 has a significant role in the regulation of osteoclastogenesis and osteoblastogenesis. This study aimed to evaluate the effect of IL-20 on periodontal destruction.

METHODS

In this study, a total of 60 participants were included, 30 of whom were systemically and periodontally healthy (control group), and 30 were systemically healthy but had periodontitis (periodontitis group). Gingival crevicular fluid (GCF) and serum samples were collected from the participants for biochemical analysis. Enzyme-linked immunosorbent assay was used to determine the levels of IL-20, tumor necrosis factor (TNF)-α, IL1β/IL-10, RANKL/osteoprotegerin (OPG), and matrix metalloproteinase-8 (MMP8). For statistical analysis, the independent t-test, Pearson correlation coefficients, and the Chi-square test were used.

RESULTS

GCF IL-20, RANKL, RANKL/OPG, serum IL-20, RANKL, RANKL/OPG, MMP-8, TNF-α, IL-1B, and IL-1β/IL-10 values were found to be statistically significantly higher in the periodontitis group than in the control group. GCF OPG and serum IL-10 values were found to be statistically significantly higher in the control group than in the periodontitis group. No statistically significant difference was observed between the groups in serum OPG values. A statistically significantly positive correlation was observed between serum IL-20 value and serum RANKL, RANKL/OPG, MMP-8, TNF-α, IL-1β values, and periodontal clinical parameters. The ROC curves showed: AUC = 0.788 for GCF IL-20, and AUC = 1.000 for serum IL-20.

CONCLUSION

According to the results of the study, IL-20 was found to be associated with periodontitis. The role of IL-20 in periodontal pathogenesis is related to osteoclastogenesis and collagen degradation. It is conceivable that IL-20 may increase bone destruction by both affecting the RANKL/OPG ratio and proinflammatory cytokines.

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.

Association between blood urea nitrogen levels and diabetic retinopathy in diabetic adults in the United States (NHANES 2005-2018)

Objective

To investigate the association between blood urea nitrogen (BUN) levels and diabetic retinopathy (DR) in adults with diabetes mellitus (DM).

Methods

Seven cycles of cross-sectional population information acquired from NHANES(national health and nutrition examination surveys) 2005-2018 were collected, from which a sample of diabetic adults was screened and separated into two groups based on whether or not they had DR, followed by weighted multivariate regression analysis. This study collected a complete set of demographic, biological, and sociological risk factor indicators for DR. Demographic risk factors comprised age, gender, and ethnicity, while biological risk factors included blood count, blood pressure, BMI, waist circumference, and glycated hemoglobin. Sociological risk factors included education level, deprivation index, smoking status, and alcohol consumption.

Results

The multiple regression model revealed a significant connection between BUN levels and DR [odds ratio =1.04, 95% confidence interval (1.03-1.05), p-value <0.0001],accounting for numerous variables. After equating BUN levels into four groups, multiple regression modeling showed the highest quartile (BUN>20 mg/dl) was 2.22 times more likely to develop DR than the lowest quartile [odds ratio =2.22, 95% confidence interval (1.69-2.93), p- value <0.0001]. Subgroup analyses revealed that gender, race, diabetes subtype, and duration of diabetes had a regulating effect on the relationship between BUN and DR.

Conclusion

BUN levels were related with an increased prevalence of DR, particularly in individuals with BUN >20 mg/dl. These findings highlight the significance of BUN level in assessing the risk of DR.

Upregulation of UHRF1 Promotes PINK1-mediated Mitophagy to Alleviates Ferroptosis in Diabetic Nephropathy

Diabetic nephropathy (DN) is a common diabetic complication. Studies show that mitophagy inhibition induced-ferroptosis plays a crucial role in DN progression. UHRF1 is associated with mitophagy and is highly expression in DN patients, however, the effect of UHRF1 on DN is still unclear. Thus, in this study, we aimed to investigate whether UHRF1 involves DN development by the mitophagy/ferroptosis pathway. We overexpressed UHRF1 using an adeno-associated virus 9 (AAV9) system in high-fat diet/streptozotocin-induced diabetic mice. Renal function index, pathological changes, mitophagy factors, and ferroptosis factors were detected in vivo. High-glucose cultured human renal proximal tubular (HK-2) cells were used as in vitro models to investigate the mechanism of UHRF1 in DN. We found that diabetic mice exhibited kidney damage, which was alleviated by UHRF1 overexpression. UHRF1 overexpression promoted PINK1-mediated mitophagy and inhibited the expression of thioredoxin interacting protein (TXNIP), a factor associated with mitochondrial dysfunction. Additionally, UHRF1 overexpression alleviated lipid peroxidation and free iron accumulation, and upregulated the expression of GPX4 and Slc7a11, indicating the inhibition effect of UHRF1 overexpression on ferroptosis. We further investigated the mechanism of UHRF1 in the mitophagy/ferroptosis pathway in DN. We found that UHRF1 overexpression promoted PINK1-mediated mitophagy via inhibiting TXNIP expression, thus suppressing ferroptosis. These findings confirmed that upregulation of UHRF1 expression alleviates DN, indicating that UHRF1 has a reno-protective effect against DN.

Swollen Feet: Considering the Paradoxical Roles of Interleukins in Nephrotic Syndrome

Interleukins are a family of 40 bioactive peptides that act through cell surface receptors to induce a variety of intracellular responses. While interleukins are most commonly associated with destructive, pro-inflammatory signaling in cells, some also play a role in promoting cellular resilience and survival. This review will highlight recent evidence of the cytoprotective actions of the interleukin 1 receptor (IL-1R)- and common gamma chain receptor (IL-Rγc)-signaling cytokines in nephrotic syndrome (NS). NS results from the injury or loss of glomerular visceral epithelial cells (i.e., podocytes). Although the causes of podocyte dysfunction vary, it is clear that pro-inflammatory cytokines play a significant role in regulating the propagation, duration and severity of disease. Pro-inflammatory cytokines signaling through IL-1R and IL-Rγc have been shown to exert anti-apoptotic effects in podocytes through the phosphoinositol-3-kinase (PI-3K)/AKT pathway, highlighting the potential utility of IL-1R- and IL-Rγc-signaling interleukins for the treatment of podocytopathy in NS. The paradoxical role of interleukins as drivers and mitigators of podocyte injury is complex and ill-defined. Emerging evidence of the cytoprotective role of some interleukins in NS highlights the urgent need for a nuanced understanding of their pro-survival benefits and reveals their potential as podocyte-sparing therapeutics for NS.

Identification of pyroptosis-related genes and potential drugs in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is one of the serious microvascular complications of diabetes mellitus (DM). A growing body of research has demonstrated that the inflammatory state plays a critical role in the incidence and development of DN. Pyroptosis is a new way of programmed cell death, which has the particularity of natural immune inflammation. The inhibition of inflammatory cytokine expression and regulation of pathways related to pyroptosis may be a novel strategy for DN treatment. The aim of this study is to identify pyroptosis-related genes and potential drugs for DN.

METHODS

DN differentially expressed pyroptosis-related genes were identified via bioinformatic analysis Gene Expression Omnibus (GEO) dataset GSE96804. Dataset GSE30528 and GSE142025 were downloaded to verify pyroptosis-related differentially expressed genes (DEGs). Least absolute shrinkage and selection operator (LASSO) regression analysis was used to construct a pyroptosis-related gene predictive model. A consensus clustering analysis was performed to identify pyroptosis-related DN subtypes. Subsequently, Gene Set Variation Analysis (GSVA), Gene Ontology (GO) function enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted to explore the differences between DN clusters. A protein-protein interaction (PPI) network was used to select hub genes and DGIdb database was utilized to screen potential therapeutic drugs/compounds targeting hub genes.

RESULTS

A total of 24 differentially expressed pyroptosis-related genes were identified in DN. A 16 gene predictive model was conducted via LASSO regression analysis. According to the expression level of these 16 genes, DN cases were divided into two subtypes, and the subtypes are mainly associated with inflammation, activation of immune response and cell metabolism. In addition, we identified 10 hub genes among these subtypes, and predicted 65 potential DN therapeutics that target key genes.

CONCLUSION

We identified two pyroptosis-related DN clusters and 65 potential therapeutical agents/compounds for DN, which might shed a light on the treatment of DN.

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.

Toll-like receptor inflammatory cascade and the development of diabetic kidney disease in children and adolescents with type 1 diabetes

AIM

This study aimed to evaluate the association of toll-like receptor (TLR) inflammatory cascade with the development of diabetic kidney disease (DKD) in children and adolescents with type 1 diabetes (T1D).

METHODS

A total of 49 T1D patients and 49 normoglycaemic (NG) subjects aged 5-20 years old were recruited. TLR2, TLR4, MYD88, NFKB, MCP1/CCL2 and IL18 mRNA expressions were measured in peripheral blood mononuclear cells by reverse transcription-quantitative polymerase chain reaction. Fasting glucose, glycated haemoglobin, serum urea, serum creatinine and urinary albumin-to-creatinine ratio (ACR) were determined.

RESULTS

The mRNA expressions of TLR2, TLR4, MYD88 and NFKB were significantly increased in the T1D group compared with the NG group. The mRNA expression levels of MCP1/CCL2 and IL18 were higher in 21 T1D patients (42.9%) (average of MCP1/CCL2: 6.6-fold and IL18: 5.8-fold) than in NG patients. Furthermore, ACR was increased in the T1D group compared with the NG group.

CONCLUSION

The increased mRNA expression of TLR2, TLR4, MYD88, NFKB, MCP1/CCL2 and IL18 favours the development of an inflammatory process that may lead to a decline in renal function and consequently DKD in children and adolescents with T1D. This suggests that these genes are early mediators of onset DKD since the beginning of the lives of the paediatric T1D patients.

Role of the adaptive immune system in diabetic kidney disease

Diabetic kidney disease (DKD) is a highly prevalent complication of diabetes and the leading cause of end-stage kidney disease. Inflammation is recognized as an important driver of progression of DKD. Activation of the immune response promotes a pro-inflammatory milieu and subsequently renal fibrosis, and a progressive loss of renal function. Although the role of the innate immune system in diabetic renal disease has been well characterized, the potential contribution of the adaptive immune system remains poorly defined. Emerging evidence in experimental models of DKD indicates an increase in the number of T cells in the circulation and in the kidney cortex, that in turn triggers secretion of inflammatory mediators such as interferon-γ and tumor necrosis factor-α, and activation of cells in innate immune response. In human studies, the number of T cells residing in the interstitial region of the kidney correlates with the degree of albuminuria in people with type 2 diabetes. Here, we review the role of the adaptive immune system, and associated cytokines, in the development of DKD. Furthermore, the potential therapeutic benefits of targeting the adaptive immune system as a means of preventing the progression of DKD are discussed.

Expression of IL-20 Receptor Subunit β Is Linked to EAE Neuropathology and CNS Neuroinflammation

Considerable clinical evidence supports that increased blood-brain barrier (BBB) permeability is linked to immune extravasation of CNS parenchyma during neuroinflammation. Although BBB permeability and immune extravasation are known to be provoked by vascular endothelial growth factor-A (i.e., VEGF-A) and C-X-C motif chemokine ligand 12 (CXCL12), respectively, the mechanisms that link both processes are still elusive. The interleukin-20 (i.e., IL-20) cytokine signaling pathway was previously implicated in VEGF-mediated angiogenesis and is known to induce cellular response by way of signaling through IL-20 receptor subunit β (i.e., IL-20RB). Dysregulated IL-20 signaling is implicated in many inflammatory pathologies, but it's contribution to neuroinflammation has yet to be reported. We hypothesize that the IL-20 cytokine, and the IL cytokine subfamily more broadly, play a key role in CNS neuroinflammation by signaling through IL-20RB, induce VEGF activity, and enhance both BBB-permeability and CXCL12-mediated immune extravasation. To address this hypothesis, we actively immunized IL-20RB^-/- mice and wild-type mice to induce experimental autoimmune encephalomyelitis (EAE) and found that IL-20RB^-/- mice showed amelioration of disease progression compared to wild-type mice. Similarly, we passively immunized IL-20RB^-/- mice and wild-type mice with myelin-reactive Th1 cells from either IL-20RB^-/- and wild-type genotype. Host IL-20RB^-/- mice showed lesser disease progression than wild-type mice, regardless of the myelin-reactive Th1 cells genotype. Using multianalyte bead-based immunoassay and ELISA, we found distinctive changes in levels of pro-inflammatory cytokines between IL-20RB^-/- mice and wild-type mice at peak of EAE. We also found detectable levels of all cytokines of the IL-20 subfamily within CNS tissues and specific alteration to IL-20 subfamily cytokines IL-19, IL-20, and IL-24, expression levels. Immunolabeling of CNS region-specific microvessels confirmed IL-20RB protein at the spinal cord microvasculature and upregulation during EAE. Microvessels isolated from macaques CNS tissues also expressed IL-20RB. Moreover, we identified the expression of all IL-20 receptor subunits: IL-22 receptor subunit α-1 (IL-22RA1), IL-20RB, and IL-20 receptor subunit α (IL-20RA) in human CNS microvessels. Notably, human cerebral microvasculature endothelial cells (HCMEC/D3) treated with IL-1β showed augmented expression of the IL-20 receptor. Lastly, IL-20-treated HCMEC/D3 showed alterations on CXCL12 apicobasal polarity consistent with a neuroinflammatory status. This evidence suggests that IL-20 subfamily cytokines may signal at the BBB via IL-20RB, triggering neuroinflammation.

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.

Pathogenic Pathways and Therapeutic Approaches Targeting Inflammation in Diabetic Nephropathy

Diabetic nephropathy (DN) is associated with an increased morbidity and mortality, resulting in elevated cost for public health systems. DN is the main cause of chronic kidney disease (CKD) and its incidence increases the number of patients that develop the end-stage renal disease (ESRD). There are growing epidemiological and preclinical evidence about the close relationship between inflammatory response and the occurrence and progression of DN. Several anti-inflammatory strategies targeting specific inflammatory mediators (cell adhesion molecules, chemokines and cytokines) and intracellular signaling pathways have shown beneficial effects in experimental models of DN, decreasing proteinuria and renal lesions. A number of inflammatory molecules have been shown useful to identify diabetic patients at high risk of developing renal complications. In this review, we focus on the key role of inflammation in the genesis and progression of DN, with a special interest in effector molecules and activated intracellular pathways leading to renal damage, as well as a comprehensive update of new therapeutic strategies targeting inflammation to prevent and/or retard renal injury.

The Role of Chemokines and Chemokine Receptors in Diabetic Nephropathy

Kidney function decline is one of the complications of diabetes mellitus and may be indicated as diabetic nephropathy (DN). DN is a chronic inflammatory disease featuring proteinuria and a decreasing glomerular filtration rate. Despite several therapeutic options being currently available, DN is still the major cause of end-stage renal disease. Accordingly, widespread innovation is needed to improve outcomes in patients with DN. Chemokines and their receptors are critically involved in the inflammatory progression in the development of DN. Although recent studies have shown multiple pathways related to the chemokine system, the specific and direct effects of chemokines and their receptors remain unclear. In this review, we provide an overview of the potential role and mechanism of chemokine systems in DN proposed in recent years. Chemokine system-related mechanisms may provide potential therapeutic targets in DN.

Matrix Metalloproteinases in Diabetic Kidney Disease

Around the world diabetic kidney disease (DKD) is the main cause of chronic kidney disease (CKD), which is characterized by mesangial expansion, glomerulosclerosis, tubular atrophy, and interstitial fibrosis. The hallmark of the pathogenesis of DKD is an increased extracellular matrix (ECM) accumulation causing thickening of the glomerular and tubular basement membranes, mesangial expansion, sclerosis, and tubulointerstitial fibrosis. The matrix metalloproteases (MMPs) family are composed of zinc-dependent enzymes involved in the degradation and hydrolysis of ECM components. Several MMPs are expressed in the kidney; nephron compartments, vasculature and connective tissue. Given their important role in DKD, several studies have been performed in patients with DKD proposing that the measurement of their activity in serum or in urine may become in the future markers of early DKD. Studies from diabetic nephropathy experimental models suggest that a balance between MMPs levels and their inhibitors is needed to maintain renal homeostasis. This review focuses in the importance of the MMPs within the kidney and their modifications at the circulation, kidney and urine in patients with DKD. We also cover the most important studies performed in experimental models of diabetes in terms of MMPs levels, renal expression and its down-regulation effect.

IL-20 in Acute Kidney Injury: Role in Pathogenesis and Potential as a Therapeutic Target

Acute kidney injury (AKI) causes over 1 million deaths worldwide every year. AKI is now recognized as a major risk factor in the development and progression of chronic kidney disease (CKD). Diabetes is the main cause of CKD as well. Renal fibrosis and inflammation are hallmarks in kidney diseases. Various cytokines contribute to the progression of renal diseases; thus, many drugs that specifically block cytokine function are designed for disease amelioration. Numerous studies showed IL-20 functions as a pro-inflammatory mediator to regulate cytokine expression in several inflammation-mediated diseases. In this review, we will outline the effects of pro-inflammatory cytokines in the pathogenesis of AKI and CKD. We also discuss the role of IL-20 in kidney diseases and provide a potential therapeutic approach of IL-20 blockade for treating renal diseases.

Pro-inflammatory cytokines are associated with podocyte damage and proximal tubular dysfunction in the early stage of diabetic kidney disease in type 2 diabetes mellitus patients

AIMS

To evaluate if there is a link between inflammation (expressed by inflammatory cytokines) and the early stage of diabetic kidney disease (DKD), as shown by markers of podocyte damage and proximal tubular (PT) dysfunction.

METHODS

In this study were enrolled 117 type 2 DM patients (36-normoalbuminuria, 42-microalbuminuria, 39- macroalbuminuria), and 11 healthy subjects. Serum and urinary IL-1 alpha, IL-8, IL-18, urinary albumin:creatinine ratio (UACR), eGFR, biomarkers of podocyte damage (podocalyxin, synaptopodin, nephrin) and of PT dysfunction (KIM-1, NAG) were assessed.

RESULTS

In multivariable regression urinary Il-1 alpha correlated positively with podocalyxin and NAG (p < 0.0001, R²= 0.57); urinary IL-8 correlated directly with synaptopodin, NAG, nephrin, and KIM-1 (p < 0.0001, R² = 0.67); urinary IL-18 correlated directly with synaptopodin, NAG, and nephrin (p < 0.0001, R² = 0.59). Serum IL-1 alpha correlated positively with nephrin, synaptopodin, NAG (P < 0.0001, R² = 0.68); serum IL-8 correlated directly with synaptopodin and NAG (p < 0.0001, R² = 0.66); serum IL-18 correlated directly with NAG, KIM-1, and podocalyxin (p < 0.0001, R²=0.647).

CONCLUSIONS

Pro-inflammatory interleukins are associated with podocyte injury and PT dysfunction in early DKD. These could exert a key role in the pathogenesis of early DKD, before the development of albuminuria.

The role of IL-20 in chronic kidney disease and diabetic nephropathy: Pathogenic and therapeutic implications

Chronic kidney disease and its complications are a major public health problem worldwide. Diabetic nephropathy has become the main contributing cause of terminal renal failure. There are now evidences that different inflammatory molecules, including proinflammatory cytokines, play a critical role in the development of microvascular diabetic complications, including nephropathy. IL-20 is emerging as a potent angiogenic, chemotactic, and proinflammatory cytokine related to several chronic inflammatory disorders likes psoriasis, atherosclerosis, and renal failure. This review discusses the role of IL-20 as a pathogenic factor in renal injury, focusing on chronic kidney disease and diabetic nephropathy, and describes potential treatment strategies based on modulation of IL-20's function.