Interleukin 37 (IL-37) Reduces High Glucose-Induced Inflammation, Oxidative Stress, and Apoptosis of Podocytes by Inhibiting the STAT3-Cyclophilin A (CypA) Signaling Pathway

The effects of CypA on apoptosis: potential target for the treatment of diseases

Cyclophilin A (CypA), the first member of cyclophilins, is distributed extensively in eukaryotic and prokaryotic cells, primarily localized in the cytoplasm. In addition to acting as an intracellular receptor for cyclosporin A (CSA), CypA plays a crucial role in diseases such as aging and tumorigenesis. Apoptosis, a form of programmed cell death, is able to balance the rate of cell viability and death. In this review, we focus on the effects of CypA on apoptosis and the relationship between specific mechanisms of CypA promoting or inhibiting apoptosis and diseases, including tumorigenesis, cardiovascular diseases, organ injury, and microbial infections. Notably, the process of CypA promoting or inhibiting apoptosis is closely related to disease development. Finally, future prospects for the association of CypA and apoptosis are discussed, and a comprehensive understanding of the effects of CypA on apoptosis in relation to diseases is expected to provide new insights into the design of CypA as a therapeutic target for diseases. KEY POINTS: • Understand the effect of CypA on apoptosis. • CypA affects apoptosis through specific pathways. • The effect of CypA on apoptosis is associated with a variety of disease processes.

The amelioration effect of antidiabetic agents on cytokine expression in patients with type 2 diabetes mellitus

Inflammation is a condition that is closely linked to diabetes mellitus type 2 (T2DM), short for T2DM several different antidiabetic medications have been produced to regulate hyperglycemia, with indications that these therapies may have anti-inflammatory effects along with their glucose-lowering efficacy. Thus, this research was planned to explore the impact of antidiabetic agents on the cytokine expression levels -interleukin (IL)-1β, IL-6, IL-17, and IL-37 when patients have T2DM. In this study, 168 eligible subject matter was split into two groups: 50 healthy individuals and 118 cases with T2DM, who were classified into two subgroups: 30 untreated patients and 88 patients treated with metformin-based therapy. The outcome exhibited a significant increase within HbA1c% and proinflammatory cytokines (i.e., IL-1β, IL- 6, and IL-17), whereas IL-37 decreased considerably in untreated cases with T2DM compared to those in subjects who are healthy. Furthermore, the results showed increased levels Regarding waist size, body mass index and assessment using that homeostasis model, cholesterol, triglycerides, low-density lipoprotein levels, and heart danger elements in untreated cases with T2DM in comparison with hygienic subjects. Notably, treated patients with T2DM revealed an ameliorative impact on HbA1c, IL-6, IL-17, IL-37, IL-1β levels and lipid profile compared with untreated patients with T2DM. Antidiabetic agents may have a beneficial activity on the inflammatory status by reducing blood glucose levels, hyperlipidemia, and proinflammatory cytokines. The anti-inflammatory activity of IL-37 can apply a potentially effective therapeutic goal in treating T2DM and its complications.

Development and implementation of a prognostic model for clear cell renal cell carcinoma based on heterogeneous TLR4 expression

Objective

Clear cell renal cell carcinoma (ccRCC) is the most common subtype among renal cell carcinomas and has the worst prognosis, originating from renal tubular epithelial cells. Toll-like receptor 4 (TLR4) plays a crucial role in ccRCC proliferation, infiltration, and metastasis. The aim of this study was to construct a prognostic scoring model for ccRCC based on TLR4 expression heterogeneity and to explore its association with immune infiltration, thereby providing insights for the treatment and prognostic evaluation of ccRCC.

Methods

Using R software, a differential analysis was conducted on normal samples and ccRCC samples, and in conjunction with the KEGG database, a correlation analysis for the clear cell renal cell carcinoma pathway (hsa05211) was carried out. We observed the expression heterogeneity of TLR4 in the TCGA-KIRC cohort and identified its related differential genes (TRGs). Based on the expression levels of TRGs, consensus clustering was employed to identify TLR4-related subtypes, and further clustering heatmaps, principal component, and single-sample gene set enrichment analyses were conducted. Overlapping differential genes (ODEGs) between subtypes were analysed, and combined with survival data, univariate Cox regression, LASSO, and multivariate Cox regression were used to establish a prognostic risk model for ccRCC. This model was subsequently evaluated through ROC analysis, risk factor correlation analysis, independent prognostic factor analysis, and intergroup differential analysis. The ssGSEA model was employed to explore immune heterogeneity in ccRCC, and the performance of the model in predicting patient prognosis was evaluated using box plots and the oncoPredict software package.

Results

In the TCGA-KIRC cohort, TLR4 expression was notably elevated in ccRCC samples compared to normal samples, correlating with improved survival in the high-expression group. The study identified distinct TLR4-related differential genes and categorized ccRCC into three subtypes with varied survival outcomes. A risk prognosis model based on overlapping differential genes was established, showing significant associations with immune cell infiltration and key immune checkpoints (PD-1, PD-L1, CTLA4). Additionally, drug sensitivity differences were observed between risk groups.

Conclusion

In the TCGA-KIRC cohort, the expression of TLR4 in ccRCC samples exhibited significant heterogeneity. Through clustering analysis, we identified that the primary immune cells across subtypes are myeloid-derived suppressor cells, central memory CD4 T cells, and regulatory T cells. Furthermore, we successfully constructed a prognostic risk model for ccRCC composed of 17 genes. This model provides valuable references for the prognosis prediction and treatment of ccRCC patients.

IL‑37 suppresses macrophage ferroptosis to attenuate diabetic atherosclerosis via the NRF2 pathway

IL-37 is a newly discovered inflammatory factor. However, the protective effect and underlying mechanisms of IL-37 on atherosclerosis remain unclear. In the present study, IL-37 was used for intraperitoneal injection in diabetic ApoE^-/- mice caused by streptozotocin. High glucose (HG)/ox-LDL was used to stimulate THP-1 original macrophage followed by IL-37 pretreatment in vitro. The atheromatous plaque area, oxidative stress and inflammation levels in ApoE^-/- mice were evaluated, and the level of macrophage ferroptosis was detected in vivo and in vitro. It was identified that IL-37 treatment significantly decreased plaque area in diabetic ApoE^-/- mice. IL-37 not only improved blood lipid levels in mice, but also reduced serum levels of inflammatory factors including IL-1β and IL-18. Furthermore, IL-37 increased GPX4 and nuclear factor erythroid 2-related factor 2 (NRF2) in the aorta of diabetic mice. In vitro experiment revealed that IL-37 inhibited HG/ox-LDL-induced ferroptosis in macrophages, as evidenced by improved cell membrane oxidation, reduced malondialdehyde production and increased GPX4 expression. Moreover, it was also found that IL-37 enhanced the nuclear translocation of NRF2 in macrophages, while ML385, a specific NRF2 inhibitor, significantly attenuated the protective effect of IL-37 on macrophage ferroptosis caused by HG/ox-LDL. In conclusion, IL-37 suppressed macrophage ferroptosis to attenuate atherosclerosis progression via activating the NRF2 pathway.

Natural products in attenuating renal inflammation via inhibiting the NLRP3 inflammasome in diabetic kidney disease

Diabetic kidney disease (DKD) is a prevalent and severe complications of diabetes and serves as the primary cause of end-stage kidney disease (ESKD) globally. Increasing evidence indicates that renal inflammation is critical in the pathogenesis of DKD. The nucleotide - binding oligomerization domain (NOD) - like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most extensively researched inflammasome complex and is considered a crucial regulator in the pathogenesis of DKD. The activation of NLRP3 inflammasome is regulated by various signaling pathways, including NF- κB, thioredoxin-interacting protein (TXNIP), and non-coding RNAs (ncRNA), among others. Natural products are chemicals extracted from living organisms in nature, and they typically possess pharmacological and biological activities. They are invaluable sources for drug design and development. Research has demonstrated that many natural products can alleviate DKD by targeting the NLRP3 inflammasome. In this review, we highlight the role of the NLRP3 inflammasome in DKD, and the pathways by which natural products fight against DKD via inhibiting the NLRP3 inflammasome activation, so as to provide novel insights for the treatment of DKD.

A Critical Appraisal of the Diagnostic and Prognostic Utility of the Anti-Inflammatory Marker IL-37 in a Clinical Setting: A Case Study of Patients with Diabetes Type 2

BACKGROUND

The role of the cytokine interleukin-37 (IL-37) has been recognized in reversing inflammation-mediated metabolic costs. The aim was to evaluate the clinical utility of this cytokine as a diagnostic and prognostic marker in patients with type 2 diabetes (T2D).

METHODS

We included 170 older (median: 66 years) individuals with T2D (females: 95) and classified as primary care attenders to assess the association of factors that describe patients with plasma IL-37 levels (expressed as quartiles) using multinomial regression models. We determined the diagnostic ability of IL-37 cut-offs to identify diabetes-related complications or patient subgroups by using Receiver Operating Characteristic analysis (c-statistics).

RESULTS

Frailty status was shown to have a suppressive effect on IL-37 circulating levels and a major modifying effect on associations of metabolic and inflammatory factors with IL-37, including the effects of treatments. Situations in which IL-37 reached a clinically significant discriminating ability included the model of IL-37 and C-Reactive Protein in differentiating among diabetic patients with low-normal/high BMI ((<25/≥25 kg/m2), and the model of IL-37 and Thyroid Stimulating Hormone in discriminating between women with/without metabolic syndrome.

CONCLUSIONS

The study has revealed limitations in using classical approaches in determining the diagnostic and prognostic utility of the cytokine IL-37 in patients with T2D and lain a foundation for new methodology approaches.

Interleukin-39 is a novel cytokine associated with type 2 diabetes mellitus and positively correlated with body mass index

INTRODUCTION

It is suggested that cytokines play a key role in the pathogenesis of type 2 diabetes mellitus (T2DM). Therefore, this study explored two recently discovered cytokines, interleukin (IL)-37 (anti-inflammatory) and IL-39 (pro-inflammatory), in T2DM due to limited data in this context.

METHODS

Serum IL-37 and IL-39 levels were determined in 106 T2DM patients and 109 controls using enzyme-linked immunosorbent assay kits.

RESULTS

Serum levels (median and interquartile range) of IL-37 (79 [47-102] vs. 60 [46-89] ng/L; probability [p] = .04) and IL-39 (66 [59-69] vs. 31 [19-42] ng/L; p < .001) were significantly elevated in T2DM patients compared to controls. As indicated by the area under the curve (AUC), IL-39 (AUC = 0.973; p < .001) was more predictable for T2DM than IL-37 (AUC = 0.582; p = .039). Elevated levels of IL-39 were significantly associated with T2DM (odds ratio = 1.30; p < .001), while IL-37 did not show this association. Classification of IL-37 and IL-39 levels by demographic and clinical characteristics of patients revealed some significant differences including gender (IL-39), body mass index (BMI; IL-37 and IL-39) and diabetic neuropathy (IL-39). BMI was positively correlated with IL-39 (correlation coefficient [r_s ] = 0.27; p = .005) and glycosylated haemoglobin (r_s  = 0.31; p = .001), and negatively correlated with age at onset (r_s  = -0.24; p = .015).

CONCLUSIONS

IL-37 and IL-39 levels were elevated in the serum of T2DM patients. Besides, IL-39 is proposed to be a novel cytokine associated with T2DM and positively correlated with BMI.

Cross-Talk between the Cytokine IL-37 and Thyroid Hormones in Modulating Chronic Inflammation Associated with Target Organ Damage in Age-Related Metabolic and Vascular Conditions

Chronic inflammation is considered to be the main mechanism contributing to the development of age-related metabolic and vascular conditions. The phases of chronic inflammation that mediate the progression of target organ damage in these conditions are poorly known, however. In particular, there is a paucity of data on the link between chronic inflammation and metabolic disorders. Based on some of our own results and recent developments in our understanding of age-related inflammation as a whole-body response, we discuss the hypothesis that cross-talk between the cytokine IL-37 and thyroid hormones could be the key regulatory mechanism that justifies the metabolic effects of chronic tissue-related inflammation. The cytokine IL-37 is emerging as a strong natural suppressor of the chronic innate immune response. The effect of this cytokine has been identified in reversing metabolic costs of chronic inflammation. Thyroid hormones are known to regulate energy metabolism. There is a close link between thyroid function and inflammation in elderly individuals. Nonlinear associations between IL-37 and thyroid hormones, considered within the wider clinical context, can improve our understanding of the phases of chronic inflammation that are associated with target organ damage in age-related metabolic and vascular conditions.

SARS-CoV-2: Receptor and Co-receptor Tropism Probability

The recent pandemic which arose from China, is caused by a pathogenic virus named "severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2)". Its rapid global expansion has inflicted an extreme public health concern. The attachment of receptor-binding domains (RBD) of the spike proteins (S) to the host cell's membrane, with or without the help of other cellular components such as proteases and especially co-receptors, is required for the first stage of its pathogenesis. In addition to humans, angiotensin-converting enzyme 2 (ACE2) is found on a wide range of vertebrate host's cellular surface. SARS-CoV-2 has a broad spectrum of tropism; thus, it can infect a vast range of tissues, organs, and hosts; even though the surface amino acids of the spike protein conflict in the receptor-binding region. Due to the heterogeneous ACE2 distribution and the presence of different domains on the SARS-CoV-2 spike protein for binding, the virus entry into diverse host cell types may depend on the host cells' receptor presentation with or without co-receptors. This review investigates multiple current types of receptor and co-receptor tropisms, with other molecular factors alongside their respective mechanisms, which facilitate the binding and entry of SARS-CoV-2 into the cells, extending the severity of the coronavirus disease 2019 (COVID-19). Understanding the pathogenesis of COVID-19 from this perspective can effectively help prevent this disease and provide more potent treatment strategies, particularly in vulnerable people with various cellular-level susceptibilities.

The emerging roles of IL-36, IL-37, and IL-38 in diabetes mellitus and its complications

Diabetes mellitus is a metabolic disease caused by a combination of genetics and environmental factors. The importance of the inflammatory response occurring in the pancreas and adipose tissue in the occurrence and progression of diabetes has been gradually accepted. Excess blood glucose and free fatty acids produce large amounts of inflammatory cytokines and chemokines through oxidative stress and endoplasmic reticulum stress. There is sufficient evidence that proinflammatory mediators, such as interleukin (IL)-1β, IL-6, macrophage chemotactic protein-1, and tumor necrosis factor-α, are engaged in the insulin resistance in peripheral adipose tissue and the apoptosis of pancreatic β-cells. IL-36, IL-37, and IL-38, as new members of the IL-1 family, play an indispensable effect in the regulation of immune system homeostasis and are involved in the pathogenesis of inflammatory and autoimmune diseases. Recently, the abnormal expression of IL-36, IL-37, and IL-38 in diabetes has been reported. In this review, we discuss the emerging functions, potential mechanisms, and future research directions on the role of IL-36, IL-37, and IL-38 in diabetes mellitus and its complications.

Clustering Inflammatory Markers with Sociodemographic and Clinical Characteristics of Patients with Diabetes Type 2 Can Support Family Physicians' Clinical Reasoning by Reducing Patients' Complexity

Diabetes mellitus type 2 (DM2) is a complex disease associated with chronic inflammation, end-organ damage, and multiple comorbidities. Initiatives are emerging for a more personalized approach in managing DM2 patients. We hypothesized that by clustering inflammatory markers with variables indicating the sociodemographic and clinical contexts of patients with DM2, we could gain insights into the hidden phenotypes and the underlying pathophysiological backgrounds thereof. We applied the k-means algorithm and a total of 30 variables in a group of 174 primary care (PC) patients with DM2 aged 50 years and above and of both genders. We included some emerging markers of inflammation, specifically, neutrophil-to-lymphocyte ratio (NLR) and the cytokines IL-17A and IL-37. Multiple regression models were used to assess associations of inflammatory markers with other variables. Overall, we observed that the cytokines were more variable than the marker NLR. The set of inflammatory markers was needed to indicate the capacity of patients in the clusters for inflammatory cell recruitment from the circulation to the tissues, and subsequently for the progression of end-organ damage and vascular complications. The hypothalamus–pituitary–thyroid hormonal axis, in addition to the cytokine IL-37, may have a suppressive, inflammation-regulatory role. These results can help PC physicians with their clinical reasoning by reducing the complexity of diabetic patients.

CD147 antibody specifically and effectively inhibits infection and cytokine storm of SARS-CoV-2 and its variants delta, alpha, beta, and gamma

SARS-CoV-2 mutations contribute to increased viral transmissibility and immune escape, compromising the effectiveness of existing vaccines and neutralizing antibodies. An in-depth investigation on COVID-19 pathogenesis is urgently needed to develop a strategy against SARS-CoV-2 variants. Here, we identified CD147 as a universal receptor for SARS-CoV-2 and its variants. Meanwhile, Meplazeumab, a humanized anti-CD147 antibody, could block cellular entry of SARS-CoV-2 and its variants-alpha, beta, gamma, and delta, with inhibition rates of 68.7, 75.7, 52.1, 52.1, and 62.3% at 60 μg/ml, respectively. Furthermore, humanized CD147 transgenic mice were susceptible to SARS-CoV-2 and its two variants, alpha and beta. When infected, these mice developed exudative alveolar pneumonia, featured by immune responses involving alveoli-infiltrated macrophages, neutrophils, and lymphocytes and activation of IL-17 signaling pathway. Mechanistically, we proposed that severe COVID-19-related cytokine storm is induced by a "spike protein-CD147-CyPA signaling axis": Infection of SARS-CoV-2 through CD147 initiated the JAK-STAT pathway, which further induced expression of cyclophilin A (CyPA); CyPA reciprocally bound to CD147 and triggered MAPK pathway. Consequently, the MAPK pathway regulated the expression of cytokines and chemokines, which promoted the development of cytokine storm. Importantly, Meplazumab could effectively inhibit viral entry and inflammation caused by SARS-CoV-2 and its variants. Therefore, our findings provided a new perspective for severe COVID-19-related pathogenesis. Furthermore, the validated universal receptor for SARS-CoV-2 and its variants can be targeted for COVID-19 treatment.

IL-37b alleviates endothelial cell apoptosis and inflammation in Kawasaki disease through IL-1R8 pathway

Kawasaki disease (KD) is an acute vasculitis of pediatric populations that may develop coronary artery aneurysms if untreated. It has been regarded as the principal cause of acquired heart disease in children of the developed countries. Interleukin (IL)-37, as one of the IL-1 family members, is a natural suppressor of inflammation that is caused by activation of innate and adaptive immunity. However, detailed roles of IL-37 in KD are largely unclear. Sera from patients with KD displayed that IL-37 level was significantly decreased compared with healthy controls (HCs). QRT-PCR and western blot analyses showed that the expression level of IL-37 variant, IL-37b, was remarkably downregulated in human umbilical vein endothelial cells (HUVECs) exposed to KD sera-treated THP1 cells. Therefore, we researched the role of IL-37b in the context of KD and hypothesized that IL-37b may have a powerful protective effect in KD patients. We first observed and substantiated the protective role of IL-37b in a mouse model of KD induced by Candida albicans cell wall extracts (CAWS). In vitro experiments demonstrated that IL-37b alleviated endothelial cell apoptosis and inflammation via IL-1R8 receptor by inhibiting ERK and NFκB activation, which were also recapitulated in the KD mouse model. Together, our findings suggest that IL-37b play an effective protective role in coronary endothelial damage in KD, providing new evidence that IL-37b is a potential candidate drug to treat KD.