Interleukin-37b inhibits the growth of murine endometriosis-like lesions by regulating proliferation, invasion, angiogenesis and inflammation

Attenuated airways inflammation and remodeling in IL-37a and IL-37b transgenic mice with an ovalbumin-induced chronic asthma

BACKGROUND

Asthma is a common chronic respiratory disease characterized by airways inflammation, hyperresponsiveness and remodeling. IL-37, an anti-inflammatory cytokine, consists of five splice isoforms, that is, a-e. Although it has been previously shown that recombinant human IL-37b is able to inhibit airway inflammation and hyperresponsiveness in animal models of asthma, the effects and difference of other IL-37 isoforms, such as IL-37a on features of asthma are unknown.

METHODS

Animal models of chronic asthma were established using IL-37a and IL-37b transgenic mice with C57BL/6J background and wild-type (WT) mice sensitized and nasally challenged with ovalbumin (OVA). Airway hyperresponsiveness was measured using FlexiVent apparatus, while histological and immunohistological stainings were employed to measure airways inflammation and remodeling indexes, including goblet cell metaplasia, mucus production, deposition of collagen, hypertrophy of airway smooth muscles and pulmonary angiogenesis.

RESULTS

Compared to WT mice, both IL-37a and IL-37b transgenic mice had significant reduced airway hyperresponsiveness and the declined total numbers of inflammatory cells, predominant eosinophils into airways and lung tissues. Furthermore, all features of airways remodeling, including degrees of mucus expression, collagen deposition, hypertrophy of smooth muscles, thickness of airways and neovascularization markedly decreased in IL-37 transgenic mice compared with OVA-treated WT mice.

CONCLUSION

Our data suggest that both IL-37a and IL-37b isoforms are able to not only ameliorate airways inflammation and airways hyperresponsiveness, but also greatly reduce airways structural changes of animal models of chronic asthma.

Fibroblast growth factor receptor 2 promotes the proliferation, migration, and invasion of ectopic stromal cells via activation of extracellular-signal-regulated kinase signaling pathway in endometriosis

Endometriosis is defined as the presence of endometrial tissues with cancer-like features in extrauterine locations. Fibroblast growth factor receptor 2 (FGFR2) is a tyrosine kinase that is involved in cancer pathogenesis. This study aimed to determine the role of FGFR2 in endometriosis. A total of 29 pairs of ectopic and eutopic endometrial tissues were collected from women with endometriosis. Endometrial tissues from women with hysteromyomas were considered as normal controls. Primary ectopic stromal cells (ESCs) were isolated from the ectopic endometrium. The role of FGFR2 in ESCs was assessed using immunohistochemistry, polymerase chain reaction, cell counting kit-8 assay, EdU staining, flow cytometry, transwell assay, and western blotting. The following signaling pathways were detected using bioinformatic analysis and confirmed in vitro. By searching the GSE171154, GSE86543, and GSE77182 datasets, FGFR2 was identified as an upregulated overlapping gene in endometriosis. Compared to eutopic and normal endometria, FGFR2 was highly expressed in ectopic tissues. Transfection of primary ESCs with FGFR2 small interfering RNA (siRNA) repressed the viability and proliferation of cells and induced apoptosis. FGFR2 siRNA inhibited the migration, invasion, and transforming growth factor-β1-triggered epithelial-mesenchymal transition (EMT). Extracellular signal-regulated kinase (ERK) signaling was found to be a downstream signaling pathway for FGFR2. The ERK1/2 inhibitor PD98059 was found to reverse the promoting effects of FGFR2 on ESC proliferation and invasion. FGFR2 silencing effectively inhibited the growth, migration, invasion, and EMT of ESCs. The effects of FGFR2 on endometriosis might be mediated via the activation of ERK signaling.

G-CSF and IL-6 may be involved in formation of endometriosis lesions by increasing the expression of angiogenic factors in neutrophils

Evidence accumulated in recent years has revealed that neutrophils are involved in the initial establishment of endometriosis, which is well-known as a chronic inflammatory disease. So far, why and how neutrophils promote the formation of early endometriosis are still unclear. In this study, using a mouse model of endometriosis, we demonstrated that endometriosis mice (EMs mice) had a significantly increased number of neutrophils in peritoneal fluids and lesions, and increased levels of granulocyte colony-stimulating factor (G-CSF) and IL-6 in serum and peritoneal fluids compared to the control group. In the neutrophils and uterine fragments co-injection experiment, neutrophils regulated by G-CSF and IL-6 had a similar effect to neutrophils from EMs mice, increasing the number, area, weight and microvessel density (MVD) of endometriotic lesions. Blocking the effect of G-CSF and IL-6 in EMs mice resulted in a decrease in the number, area and weight of endometriotic lesions. Following the depletion of neutrophils in vivo using a anti-Ly6G antibody, the MVD in the lesions of mice treated with neutrophils from EMs mice and neutrophils from pG/pI6 mice were significantly reduced. Neutrophils from EMs mice and neutrophils from pG/pI6 mice altered the expression levels of Mmp9, Bv8 and Trail genes compared to the neutrophils from PBS-treated mice. IL-6 together with G-CSF induced a higher expression of phospho-STAT3 and STAT3 in neutrophils. These findings suggest that neutrophils modulated by G-CSF and IL-6 through the STAT3 pathway alter the expression levels of the angiogenesis-related genes Mmp9, Bv8 and Trail, and may promote the establishment of early endometriosis.

Recombinant human IL-37 inhibited endometriosis development in a mouse model through increasing Th1/Th2 ratio by inducing the maturation of dendritic cells

BACKGROUND

Endometriosis is a serious reproductive and general health consequences. Recombinant human IL-37 (rhIL-37) is an inhibitor of inflammation.

METHODS

ELISA assay was performed to detect the concentration of cytokines. Flow cytometry was used to analyze cell proportion. Besides, qRT-PCR and western blotting assay were used to detect the level of gene and protein, respectively. Transwell co-culture system was used for the co-culture of dendritic cells (DCs) and CD4⁺T cells.

RESULTS

Our data showed that rhIL-37 inhibited the development of ectopic lesions in the mice with endometriosis, increased Th1/Th2 ratio and induced DCs maturation. The co-culture system of DCs and CD4⁺T cells demonstrated that rhIL-37 increased Th1/Th2 cell ratio through promoting DCs maturation. Moreover, the expression of IL-4 in the DCs derived from healthy mice was inhibited by rhIL-37 treatment. rhIL-37 increased Th1/Th2 cell ratio through inhibiting IL-4 in DCs. Subsequently, our results proved that rhIL-37 promoted the maturation of DCs via inhibiting phosphorylation of STAT3. Activation of STAT3 could reverse rhIL-37-induced maturation of DCs.

CONCLUSION

Overall, rhIL-37 could protect against endometriosis through increasing the ratio of Th1/Th2 cells via inducing DCs maturation and inhibiting IL-4 expression in the DCs. Furthermore, rhIL-37 induced DCs maturation by inhibiting STAT3 phosphorylation. Our data confirmed the protective effect of rhIL-37 in endometriosis. These data may provide a novel idea for the treatment of the disease.

Role of inflammation in benign gynecologic disorders: from pathogenesis to novel therapies†

Emerging evidence supports the notion that inflammation fosters the development of common benign gynecologic disorders, including uterine leiomyoma, endometriosis, and adenomyosis. Numerous cytokines, chemokines, and growth and transcription factors have indisputable roles in the establishment and maintenance of benign gynecologic disorders by initiating complex cascades that promote proliferation, angiogenesis, and lesion progression. The interaction between inflammation and benign gynecologic disorders is orchestrated by a plethora of factors, including sex steroids, genetics, epigenetics, extracellular matrix, stem cells, cardiometabolic risk factors, diet, vitamin D, and the immune system. The role of inflammation in these disorders is not limited to local pathobiology but also extends to involve clinical sequelae that range from those confined to the reproductive tract, such as infertility and gynecologic malignancies, to systemic complications such as cardiovascular disease. Enhanced understanding of the intricate mechanisms of this association will introduce us to unvisited pathophysiological perspectives and guide future diagnostic and therapeutic implications aimed at reducing the burden of these disorders. Utilization of inflammatory markers, microRNA, and molecular imaging as diagnostic adjuncts may be valuable, noninvasive techniques for prompt detection of benign gynecologic disorders. Further, use of novel as well as previously established therapeutics, such as immunomodulators, hormonal treatments, cardiometabolic medications, and cyclooxygenase-2 and NF-κB inhibitors, can target inflammatory pathways involved in their pathogenesis. In this comprehensive review, we aim to dissect the existing literature on the role of inflammation in benign gynecologic disorders, including the proposed underlying mechanisms and complex interactions, its contribution to clinical sequelae, and the clinical implications this role entails.

Current Understanding of IL-37 in Human Health and Disease

IL-37 is a recently discovered cytokine in the IL-1 family exerting broad protective effects on inflammatory diseases, autoimmune diseases, and cancer. Immune and non-immune cells produce the IL-37 precursor upon pro-inflammatory stimuli. Intracellularly, caspase-1 cleaves and activates IL-37, and its mature form binds to Smad3; this complex translocates into the nucleus where it suppresses cytokine production, consequently reducing inflammation. Extracellularly, IL-37 forms a complex with IL-18Rα and IL-1R8 (formerly TIR8 or SIGIRR) that transduces anti-inflammatory signals by the suppression of NF-κB and MAPK and the activation of Mer-PTEN-DOK pathways. During inflammation, IL-37 suppresses the expression of several pro-inflammatory cytokine in favor to the expression of the anti-inflammatory ones by the regulation of macrophage polarization, lipid metabolism, inflammasome function, TSLP synthesis and miRNAs function. Moreover, IL-37 not only regulates the innate and acquired immunity, but also improves aging-associated immunosenescence. Furthermore, IL-37 exerts an inhibitory effect on tumor angiogenesis and metastasis, and progression. Finally, IL-37 may have a potential ability to reduce excessive inflammation since it is aberrantly expressed in patients with inflammatory diseases, autoimmune diseases, and cancer, thus, it may be used as a marker for different types of diseases. Therefore, this review provides an updated view of the role of IL-37 in human health and disease, and discusses the potential of IL-37 as a therapeutic target and biomarker in inflammatory diseases, autoimmune diseases, and cancer.

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.

IL-1 Family Antagonists in Mouse and Human Skin Inflammation

Interleukin (IL)-1 family cytokines initiate inflammatory responses, and shape innate and adaptive immunity. They play important roles in host defense, but excessive immune activation can also lead to the development of chronic inflammatory diseases. Dysregulated IL-1 family signaling is observed in a variety of skin disorders. In particular, IL-1 family cytokines have been linked to the pathogenesis of psoriasis and atopic dermatitis. The biological activity of pro-inflammatory IL-1 family agonists is controlled by the natural receptor antagonists IL-1Ra and IL-36Ra, as well as by the regulatory cytokines IL-37 and IL-38. These four anti-inflammatory IL-1 family members are constitutively and highly expressed at steady state in the epidermis, where keratinocytes are a major producing cell type. In this review, we provide an overview of the current knowledge concerning their regulatory roles in skin biology and inflammation and their therapeutic potential in human inflammatory skin diseases. We further highlight some common misunderstandings and less well-known observations, which persist in the field despite recent extensive interest for these cytokines.